Specialty: Pulmonary Medicine
Brigham and Women’s Hospital
New England Journal of Medicine
10 Shattuck Street
Boston, MA 02115
The following is a list of recent publications for which this Partners Asthma Center physician has been cited as an author in PubMed databases. Study abstracts have been provided for your convenience.
van's Gravesande, K. S., M. E. Wechsler, et al. (2003). "Association of a missense mutation in the NOS3 gene with exhaled nitric oxide levels." Am J Respir Crit Care Med 168(2): 228-31.
There is evidence that genetic factors affect nitric oxide formation and that sequence variants in the nitric oxide synthase genes contribute to the observed variance of nitric oxide levels in exhaled air (fraction of expired nitric oxide, FENO) in subjects with asthma. We identified a strong association between a known functional NOS3 missense sequence variant in the endothelial nitric oxide gene (G894T) and FENO level in a cohort of subjects with asthma. Age- and sex-adjusted FENO levels were lowest in asthmatic subjects with the TT genotype (geometric mean FENO [95% CI] = 7.17 [4.48 to 11.48] ppb) and were significantly higher in those with either the GT genotype (geometric mean FENO [95% CI] = 17.11 [13.80 to 21.23] ppb) or the GG genotype (geometric mean FENO [95% CI] = 12.06 [9.91 to 14.67] ppb) (F2,59 = 5.97, p = 0.004). The G894T DNA variant explained 16.3% of the residual variance in FENO levels. Our results demonstrate that the endothelial nitric oxide synthase, a nitric oxide synthase constitutively expressed in epithelial cells, plays an important role in determining measured levels of exhaled nitric oxide, a marker of the asthmatic condition.
Tschumperlin, D. J., J. D. Shively, et al. (2003). "Mechanical stress triggers selective release of fibrotic mediators from bronchial epithelium." Am J Respir Cell Mol Biol 28(2): 142-9.
Transforming growth factor-beta (TGF-beta) and endothelin (ET) are found in elevated amounts in the airways of individuals with asthma. The cellular source of these peptides and their role in mediating the airway fibrosis of chronic asthma are unknown. In response to mechanical stresses similar to those occurring in vivo during airway constriction, bronchial epithelial cells increase the steady-state level of mRNA for both ET-1 and ET-2, followed by increased release of ET protein. Mechanical stress also enhances release of TGF-beta2 from a preformed cell-associated pool. TGF-beta2 and ET act individually and, more importantly, synergistically to promote fibrotic protein synthesis in reporter fibroblasts. To confirm the role of these intermediates in stress-induced fibrosis, conditioned medium from mechanically stressed bronchial epithelial cells was shown to elicit fibrotic protein synthesis in reporter fibroblasts; this effect was significantly inhibited by combined treatment with ET receptor antagonists and a neutralizing antibody to TGF-beta2. These data are consistent with a primary pathogenic role for mechanical stress-induced release of both TGF-beta2 and ET in the subepithelial fibrosis that characterizes chronic asthma.
Silverman, E. S. and J. M. Drazen (2003). "Immunostimulatory DNA for asthma: better than eating dirt." Am J Respir Cell Mol Biol 28(6): 645-7.
Shore, S. A. and J. M. Drazen (2003). "Beta-agonists and asthma: too much of a good thing?" J Clin Invest 112(4): 495-7.
In an unusual paradox, asthmatics who are chronically treated with bronchodilating beta-agonists sometimes experience a worsening of their condition. A new study describes one possible mechanism and reveals a potential new therapeutic target in the treatment of asthma.
Levy, B. D., G. T. De Sanctis, et al. (2003). "Lipoxins and aspirin-triggered lipoxins in airway responses." Adv Exp Med Biol 525: 19-23.
Here, we have demonstrated potent inhibition of allergen-mediated pulmonary inflammation and airway hyper-responsiveness by a novel dual-pronged action of LX's. Moreover, these results indicate that LX's play pivotal and previously unappreciated roles in regulating allergy and pulmonary inflammation.
Kalayci, O., M. Wechsler, et al. (2003). "LTC4 production by eosinophils in asthmatic subjects with alternative forms of ALOX-5 core promoter." Adv Exp Med Biol 525: 11-4.
Grasemann, H., K. S. van's Gravesande, et al. (2003). "Endothelial nitric oxide synthase variants in cystic fibrosis lung disease." Am J Respir Crit Care Med 167(3): 390-4.
Variants in the genes encoding for the nitric oxide synthases may act as disease modifier loci in cystic fibrosis, affecting both an individual's nitric oxide level and pulmonary function. In this study, the 894G/T variant in exon 7 of the endothelial nitric oxide synthase gene was related to exhaled nitric oxide and pulmonary function in 70 cystic fibrosis patients who were aged 14.8 +/- 6.9 years (mean +/- SD), with a FEV1 of 69.4 +/- 24.8% predicted. Although there was no association between endothelial nitric oxide synthase genotypes and exhaled nitric oxide in males, nitric oxide levels were significantly higher in female cystic fibrosis patients with an 894T mutant allele, compared with female patients homozygous for the 894G wild-type allele (7.0 +/- 4.4 versus 3.6 +/- 1.9 parts per billion, p = 0.02). Furthermore, in female patients, colonization of airways with Pseudomonas aeruginosa was significantly (p < 0.05) less frequent when carrying an 894T mutant allele as compared with wild type. These data suggest that the 894T variant in the endothelial nitric oxide synthase gene is associated with increased airway nitric oxide formation in female cystic fibrosis patients, possibly affecting colonization of airways with P. aeruginosa.
Grasemann, H., K. S. van's Gravesande, et al. (2003). "Effects of sex and of gene variants in constitutive nitric oxide synthases on exhaled nitric oxide." Am J Respir Crit Care Med 167(8): 1113-6.
Genetic factors may contribute to the variability of exhaled nitric oxide in healthy individuals. We studied exhaled nitric oxide and genetic variants in both neuronal and endothelial nitric oxide synthases in 105 healthy nonsmoking and smoking subjects. Genomic DNA was screened for a repeat polymorphism in intron 20 of the neuronal nitric oxide synthase gene and for the 894G/T mutation of the endothelial nitric oxide synthase gene. Exhaled nitric oxide was significantly higher in males than females among both nonsmokers (p < 0.0001) and smokers (p = 0.003). No association was found between exhaled nitric oxide and the endothelial nitric oxide synthase gene variant. However, healthy nonsmoking females with greater numbers of repeats (i.e., both alleles with 12 or more repeats) in neuronal nitric oxide synthase had significantly lower nitric oxide levels than did females with fewer numbers of repeats (i.e., at least one allele with fewer than 12 repeats) (13.6 +/- 1.6 versus 19.4 +/- 1.6 ppb, p = 0.02). No association was found between exhaled nitric oxide and neuronal nitric oxide synthase genotype in males. These data suggest that variants in the neuronal nitric oxide synthase gene contribute to the variability of airway nitric oxide concentrations in healthy females.
Drazen, J. M. (2003). "Inappropriate advertising of dietary supplements." N Engl J Med 348(9): 777-8.
Drazen, J. M. (2003). "Asthma and the human genome project: summary of the 45th Annual Thomas L. Petty Aspen Lung Conference." Chest 123(3 Suppl): 447S-9S.
Drazen, J. M. (2003). "Case clusters of the severe acute respiratory syndrome." N Engl J Med 348(20): e6-7.
Drazen, J. M. (2003). "Controlling research trials." N Engl J Med 348(14): 1377-80.
Drazen, J. M. and E. W. Campion (2003). "SARS, the Internet, and the Journal." N Engl J Med 348(20): 2029.
Drazen, J. M. (2003). "Leukotrienes in asthma." Adv Exp Med Biol 525: 1-5.
Drazen, J. M. and A. M. Epstein (2003). "Guidance concerning surgery for emphysema." N Engl J Med 348(21): 2134-6.
Drazen, J. M., J. R. Ingelfinger, et al. (2003). "Expression of concern: Schiffl H, et Al. Daily hemodialysis and the outcome of acute renal failure. N Engl J Med 2002;346:305-10." N Engl J Med 348(21): 2137.
Drazen, J. M. (2003). "Legislative myopia on stem cells." N Engl J Med 349(3): 300.
Drazen, J. M. (2003). "SARS--looking back over the first 100 days." N Engl J Med 349(4): 319-20.
Curfman, G. D., S. Morrissey, et al. (2003). "Notice of retraction." N Engl J Med 348(10): 945.
Curfman, G. D., S. Morrissey, et al. (2003). "Notice of duplicate publication." N Engl J Med 348(22): 2254.
Tschumperlin, D. J., J. D. Shively, et al. (2002). "Bronchial epithelial compression regulates MAP kinase signaling and HB-EGF-like growth factor expression." Am J Physiol Lung Cell Mol Physiol 282(5): L904-11.
Airway smooth muscle constriction leads to the development of compressive stress on bronchial epithelial cells. Normal human bronchial epithelial cells exposed to an apical-to-basal transcellular pressure difference equivalent to the computed stress in the airway during bronchoconstriction demonstrate enhanced phosphorylation of extracellular signal-regulated kinase (ERK). The response is pressure dependent and rapid, with phosphorylation increasing 14-fold in 30 min, and selective, since p38 and c-Jun NH(2)-terminal kinase phosphorylation remains unchanged after pressure application. Transcellular pressure also elicits a ninefold increase in expression of mRNA encoding heparin-binding epidermal growth factor-like growth factor (HB-EGF) after 1 h, followed by prominent immunostaining for pro-HB-EGF after 6 h. Inhibition of the ERK pathway with PD-98059 results in a dose-dependent reduction in pressure-induced HB-EGF gene expression. The magnitude of the HB-EGF response to transcellular pressure and tumor necrosis factor (TNF)-alpha (1 ng/ml) is similar, and the combined mechanical and inflammatory stimulus is more effective than either stimulus alone. These results demonstrate that compressive stress is a selective and potent activator of signal transduction and gene expression in bronchial epithelial cells.
Szefler, S. J., R. J. Martin, et al. (2002). "Significant variability in response to inhaled corticosteroids for persistent asthma." J Allergy Clin Immunol 109(3): 410-8.
BACKGROUND: A clinical model is needed to compare inhaled corticosteroids (ICSs) with respect to efficacy. OBJECTIVE: The purpose of this investigation was to compare the relative beneficial and systemic effects in a dose-response relationship for 2 ICSs. METHODS: A 24-week, parallel, open-label, multicenter trial examined the benefit-risk ratio of 2 ICSs in persistent asthma. Benefit was assessed by improvements in FEV(1) and PC(20); risk was assessed by overnight plasma cortisol suppression. Thirty subjects were randomized to either beclomethasone dipropionate (BDP) 168, 672, and 1344 microg/day (n = 15) or fluticasone propionate (FP) 88, 352, and 704 microg/day (n = 15), both administered by means of a metered dose inhaler (MDI) with chlorofluorocarbon propellant via a spacer, in 3 consecutive 6-week intervals; this was followed by 3 weeks of FP dry powder inhaler (DPI) 2000 microg/day. RESULTS: Maximum FEV(1) response occurred with the low dose for FP-MDI and the medium dose for BDP-MDI and was not further increased by treatment with FP-DPI. Near-maximum methacholine PC(20) improvement occurred with the low dose for FP-MDI and the medium dose for BDP-MDI. Both BDP-MDI and FP-MDI caused dose-dependent cortisol suppression. Responsiveness to ICS treatment was found to vary markedly among subjects. Good (>15%) FEV(1) response, in contrast to poor (<5%) response, was found to be associated with high exhaled nitric oxide (median, 17.6 vs 11.1 ppb), high bronchodilator reversibility (25.2% vs 8.8%), and a low FEV(1)/forced vital capacity ratio (0.63 vs 0.73) before treatment. Excellent (>3 doubling dilutions) improvement in PC(20), in contrast to poor (<1 doubling dilution) improvement, was found to be associated with high sputum eosinophil levels (3.4% vs 0.1%) and older age at onset of asthma (age, 20-29 years vs <10 years). CONCLUSIONS: Near-maximal FEV(1) and PC(20) effects occurred with low-medium dose for both ICSs in the subjects studied. High-dose ICS therapy did not significantly increase the efficacy measures that were evaluated, but it did increase the systemic effect measure, overnight cortisol secretion. Significant intersubject variability in response occurred with both ICSs. It is possible that higher doses of ICSs are necessary to manage more severe patients or to achieve goals of therapy not evaluated in this study, such as prevention of asthma exacerbations.
Slutsky, A. S. and J. M. Drazen (2002). "Ventilation with small tidal volumes." N Engl J Med 347(9): 630-1.
Silverman, E. K., J. D. Mosley, et al. (2002). "Genome-wide linkage analysis of severe, early-onset chronic obstructive pulmonary disease: airflow obstruction and chronic bronchitis phenotypes." Hum Mol Genet 11(6): 623-32.
Familial aggregation of chronic obstructive pulmonary disease (COPD) has been demonstrated, but linkage analysis of COPD-related phenotypes has not been reported previously. An autosomal 10 cM genome-wide scan of short tandem repeat (STR) polymorphic markers was analyzed for linkage to COPD-related phenotypes in 585 members of 72 pedigrees ascertained through severe, early-onset COPD probands without severe alpha1-antitrypsin deficiency. Multipoint non-parametric linkage analysis (using the ALLEGRO program) was performed for qualitative phenotypes including moderate airflow obstruction [forced expiratory volume at one second (FEV(1)) < 60% predicted, FEV(1)/FVC < 90% predicted], mild airflow obstruction (FEV(1) < 80% predicted, FEV(1)/FVC < 90% predicted) and chronic bronchitis. The strongest evidence for linkage in all subjects was observed at chromosomes 12 (LOD = 1.70) and 19 (LOD = 1.54) for moderate airflow obstruction, chromosomes 8 (LOD = 1.36) and 19 (LOD = 1.09) for mild airflow obstruction and chromosomes 19 (LOD = 1.21) and 22 (LOD = 1.37) for chronic bronchitis. Restricting analysis to cigarette smokers only provided increased evidence for linkage of mild airflow obstruction and chronic bronchitis to several genomic regions; for mild airflow obstruction in smokers only, the maximum LOD was 1.64 at chromosome 19, whereas for chronic bronchitis in smokers only, the maximum LOD was 2.08 at chromosome 22. On chromosome 12p, 12 additional STR markers were genotyped, which provided additional support for an airflow obstruction locus in that region with a non-parametric multipoint approach for moderate airflow obstruction (LOD = 2.13) and mild airflow obstruction (LOD = 1.43). Using a dominant model with the STR markers on 12p, two point parametric linkage analysis of all subjects demonstrated a maximum LOD score of 2.09 for moderate airflow obstruction and 2.61 for mild airflow obstruction. In smokers only, the maximum two point LOD score for mild airflow obstruction was 3.14. These observations provide suggestive evidence that there is a locus on chromosome 12p which contributes to susceptibility to early-onset COPD.
Silverman, E. K., L. J. Palmer, et al. (2002). "Genomewide linkage analysis of quantitative spirometric phenotypes in severe early-onset chronic obstructive pulmonary disease." Am J Hum Genet 70(5): 1229-39.
Chronic obstructive pulmonary disease (COPD) is a common, complex disease associated with substantial morbidity and mortality. COPD is defined by irreversible airflow obstruction; airflow obstruction is typically determined by reductions in quantitative spirometric indices, including forced expiratory volume at 1 s (FEV(1)) and the ratio of FEV(1) to forced vital capacity (FVC). To identify genetic determinants of quantitative spirometric phenotypes, an autosomal 10-cM genomewide scan of short tandem repeat (STR) polymorphic markers was performed in 72 pedigrees (585 individuals) ascertained through probands with severe early-onset COPD. Multipoint variance-component linkage analysis (using SOLAR) was performed for quantitative phenotypes, including FEV(1), FVC, and FEV(1)/FVC. In the initial genomewide scan, significant evidence for linkage to FEV(1)/FVC was demonstrated on chromosome 2q (LOD score 4.12 at 222 cM). Suggestive evidence was found for linkage to FEV(1)/FVC on chromosomes 1 (LOD score 1.92 at 120 cM) and 17 (LOD score 2.03 at 67 cM) and to FVC on chromosome 1 (LOD score 2.05 at 13 cM). The highest LOD score for FEV(1) in the initial genomewide scan was 1.53, on chromosome 12, at 36 cM. After inclusion of 12 additional STR markers on chromosome 12p, which had been previously genotyped in this population, suggestive evidence for linkage of FEV(1) (LOD score 2.43 at 37 cM) to this region was demonstrated. These observations provide both significant evidence for an early-onset COPD-susceptibility locus on chromosome 2 and suggestive evidence for linkage of spirometry-related phenotypes to several other genomic regions. The significant linkage of FEV(1)/FVC to chromosome 2q could reflect one or more genes influencing the development of airflow obstruction or dysanapsis.
Silverman, E. S., R. M. Baron, et al. (2002). "Constitutive and cytokine-induced expression of the ETS transcription factor ESE-3 in the lung." Am J Respir Cell Mol Biol 27(6): 697-704.
Family studies of asthma suggest that the genes ESE-2 and ESE-3 contain polymorphisms that contribute to disease susceptibility. Each gene codes for an ETS transcription factor that is characterized by epithelium-restricted constitutive expression and may function as a context-dependent activator or repressor of transcription; however, nothing is known about the role of these genes in lung homeostasis or the pathogenesis of airway disease. In this study, we show that ESE-3 mRNA and protein are constitutively expressed in bronchial and mucous gland epithelial cells. Consistent with these findings, ESE-3 mRNA is constitutively expressed in human bronchial epithelial cells grown in tissue culture. In contrast, ESE-2 mRNA could not be detected in the lung or cultured human bronchial epithelial cells. Human bronchial smooth muscle cells and fibroblasts do not constitutively express ESE-3; however, after stimulation with interleukin-1beta or tumor necrosis factor-alpha, levels of ESE-3 mRNA and protein increase dramatically by 24 h. This cytokine induction is dose-dependent and abrogated by specific inhibitors of the MEK1/2 (U0126) and p38 (SB03580) signal transduction pathways. Overexpression of ESE-3 protein in 3T3 cells and human bronchial smooth muscle cells inhibits MMP-1 promoter activity, suggesting that ESE-3 may function as a transcriptional repressor.
Shikanai, T., E. S. Silverman, et al. (2002). "Sequence variants in the FcepsilonRI alpha chain gene." J Appl Physiol 93(1): 37-41.
There is a relationship between IgE levels and expression of high-affinity IgE receptors (FcepsilonRI). Because the alpha chain is the only portion of the receptor that binds directly to IgE, we reasoned that sequence variants in the FcepsilonRI alpha gene may exist that alter these binding events. We screened all of the exons and the promoter region of the FcepsilonRI alpha chain gene with genomic DNA from 389 asthmatic and 341 normal control subjects for mutations by using single-stranded conformational polymorphism analysis. No nonsynonomous single nucleotide polymorphisms (SNPs) were identified in the coding region. Three SNPs were found in the promoter region: an A/C transversion at -770 from the translation start site; a G/A transition at -664; and a T/C transition at -335. No differences in allele frequencies were detected between asthmatic subjects and controls. Homozygosity for the C variant at locus -335 was more common in Caucasian asthmatic patients with IgE levels in the lower quartile than in the upper quartile (P = 0.032). An analysis of highly polymorphic SNPs indicated that this association is unlikely to be due to population substructure. We conclude that homozygosity for the C allele of FcepsilonRI alpha chain variant is associated with lower IgE levels.
Palmer, L. J., E. S. Silverman, et al. (2002). "Pharmacogenetics of asthma." Am J Respir Crit Care Med 165(7): 861-6.
Oguma, T., K. Asano, et al. (2002). "Cyclooxygenase-2 expression during allergic inflammation in guinea-pig lungs." Am J Respir Crit Care Med 165(3): 382-6.
Prostaglandins and thromboxanes are important modulators of airway physiology. The synthesis of these mediators depends on two isoforms of cyclooxygenase (COX), constitutive COX-1 and inducible COX-2. COX-2 expression has been observed in various inflammatory diseases, but not all aspects of the expression and the role of COX-2 in conditions of allergic inflammation such as asthma are clear. In the present study, we examined the 72-h kinetics of the expression of COX-isoform mRNA in ovalbumin-sensitized and -challenged guinea-pig lungs. The sensitized animals showed a robust and transient induction of COX-2 mRNA expression within 1 h after ovalbumin challenge, whereas their COX-1 mRNA levels remained unchanged. Upregulation of the level and activity of COX-2 protein followed the induction of COX-2 mRNA. Lung slices harvested from ovalbumin-challenged animals released more prostaglandin D(2) and prostaglandin E(2) spontaneously or in response to A23187 (10 microM) ex vivo than did those from unchallenged animals. This response was significantly blocked by the COX-2 selective inhibitors, NS-398 and JTE-522. In vivo administration of NS-398 significantly inhibited the accumulation of eosinophils and neutrophils in the lungs. In conclusion, de novo COX-2 expression during allergic inflammation modifies prostanoid synthesis in the lung and airway pathophysiology.
Mushlin, S. B., J. M. Drazen, et al. (2002). "Case records of the Massachusetts General Hospital. Weekly clinicopathological exercises. Case 33-2002. A 28-year-old woman with ocular inflammation, fever, and headache." N Engl J Med 347(17): 1350-7.
Martin, R. J., S. J. Szefler, et al. (2002). "Systemic effect comparisons of six inhaled corticosteroid preparations." Am J Respir Crit Care Med 165(10): 1377-83.
The goal of this study was to establish a reliable method to evaluate systemic bioavailability and to determine equisystemic effects (microgram dose producing equal systemic cortisol suppression) of inhaled corticosteroids (ICS). Steroid naive asthma subjects (n = 156) were enrolled at six centers. A 1-week doubling dose design was used for each of six ICS and matched placebos for a total of four doses. Systemic effect was evaluated by hourly plasma cortisol concentrations (8 P.M. to 8 A.M.), 12- and 24-hour urine cortisol concentrations, and a morning blood osteocalcin. The area under the concentration-time curve for hourly cortisol concentrations was the best outcome variable to assess systemic effect. For the six ICS and matching placebos (beclomethasone-chlorofluorocarbon [CFC], budesonide dry powder inhaler [DPI], fluticasone DPI, fluticasone-CFC metered dose inhaler [MDI], flunisolide-CFC, and triamcinolone-CFC), only the placebo group and fluticasone DPI did not demonstrate a significant dose-response effect. Thus microgram comparison of all ICS could only be performed at a 10% cortisol suppression: flunisolide-CFC - 936; triamcinolone-CFC - 787; beclomethasone-CFC - 548; fluticasone DPI - 445; budesonide DPI - 268; fluticasone-CFC MDI - 111. This study represents the first step in evaluation of ICS efficacy based on equisystemic (cortisol suppression) effects of a given ICS, rather than doses judged arbitrarily to be comparable on a microgram basis.
Levy, B. D., G. T. De Sanctis, et al. (2002). "Multi-pronged inhibition of airway hyper-responsiveness and inflammation by lipoxin A(4)." Nat Med 8(9): 1018-23.
The prevalence of asthma continues to increase and its optimal treatment remains a challenge. Here, we investigated the actions of lipoxin A(4) (LXA(4)) and its leukocyte receptor in pulmonary inflammation using a murine model of asthma. Allergen challenge initiated airway biosynthesis of LXA(4) and increased expression of its receptor. Administration of a stable analog of LXA(4) blocked both airway hyper-responsiveness and pulmonary inflammation, as shown by decreased leukocytes and mediators, including interleukin-5, interleukin-13, eotaxin, prostanoids and cysteinyl leukotrienes. Moreover, transgenic expression of human LXA(4) receptors in murine leukocytes led to significant inhibition of pulmonary inflammation and eicosanoid-initiated eosinophil tissue infiltration. Inhibition of airway hyper-responsiveness and allergic airway inflammation with a stable LXA(4) analog highlights a unique counter-regulatory profile for the LXA(4) system and its leukocyte receptor in airway responses. Moreover, our findings suggest that lipoxin and related pathways offer novel multi-pronged therapeutic approaches for human asthma.
Hrousis, C. A., B. J. Wiggs, et al. (2002). "Mucosal folding in biologic vessels." J Biomech Eng 124(4): 334-41.
A two-layer model is used to simulate the mechanical behavior of an airway or other biological vessel under external compressive stress or smooth muscle constriction sufficient to cause longitudinal mucosal buckling. Analytic andfinite element numerical methods are used to examine the onset of buckling. Post-buckling solutions are obtained by finite element analysis, then verified with large-scale physical model experiments. The two-layer model provides insight into how the stiffness of a vessel wall changes due to changes in the geometry and intrinsic material stiffnesses of the wall components. Specifically, it predicts that the number of mucosal folds in the buckled state is diminished most by increased thickness of the inner collagen-rich layer, and relatively little by increased thickness of the outer submucosal layer. An increase in the ratio of the inner to outer material stiffnesses causes an intermediate reduction in the number of folds. Results are cast in a simple form that can easily be used to predict buckling in a variety of vessels. The model quantitatively confirms that an increase in the thickness of the inner layer leads to a reduction in the number of mucosal folds, and further, that this can lead to increased vessel collapse at high levels of smooth muscle constriction.
Hare, J. M., G. C. Nguyen, et al. (2002). "Exhaled nitric oxide: a marker of pulmonary hemodynamics in heart failure." J Am Coll Cardiol 40(6): 1114-9.
OBJECTIVES: We sought to test the hypothesis that patients with decompensated heart failure (HF) lose a compensatory process whereby nitric oxide (NO) maintains pulmonary vascular tone. BACKGROUND: Exhaled nitric oxide (eNO) partially reflects vascular endothelial NO release. Levels of eNO are elevated in patients with compensated HF and correlate inversely with pulmonary artery pressures (PAP), reflecting pulmonary vasodilatory activity. METHODS: We measured the mean mixed expired NO content of a vital-capacity breath using chemiluminescence in patients with compensated HF (n = 30), decompensated HF (n = 7) and in normal control subjects (n = 90). Pulmonary artery pressures were also measured in patients with HF. The eNO and PAP were determined sequentially during therapy with intravenous vasodilators in patients with decompensated HF (n = 7) and in an additional group of patients with HF (n = 13) before and during administration of milrinone. RESULTS: The eNO was higher in patients with HF than in control subjects (9.9 +/- 1.1 ppb vs. 6.2 +/- 0.4 ppb, p = 0.002) and inversely correlated with PAP (r = -0.81, p < 0.00001). In marked contrast, patients with decompensated HF exhibited even higher levels of eNO (20.4 +/- 6.2 ppb) and PAP, but there was a loss of the inverse relationship between these two variables. During therapy (7.3 +/- 6 days) with sodium nitroprusside and diuresis, hemodynamics improved, eNO concentrations fell (11.2 +/- 1.2 ppb vs. before treatment, p < 0.05), and the relationship between eNO and PAP was restored. After milrinone, eNO rose proportionally with decreased PAP (p < 0.05). CONCLUSIONS: Elevated eNO may reflect a compensatory circulatory mechanism in HF that is lost in patients with clinically decompensated HF. The eNO may be an easily obtainable and quantifiable measure of the response to therapy in advanced HF.
Grasemann, H., K. Storm van's Gravesande, et al. (2002). "Nasal nitric oxide levels in cystic fibrosis patients are associated with a neuronal NO synthase (NOS1) gene polymorphism." Nitric Oxide 6(2): 236-41.
Nitric oxide (NO) plays an important role in a number of physiological processes in the airways, including host defense. Although the exact cellular and molecular source of the NO formation in airways is unknown, there is recent evidence that neuronal NO synthase (NOS1) contributes significantly to NO in the lower airways of cystic fibrosis (CF) patients. NOS1 protein has been shown to be expressed in nasal epithelium, suggesting an involvement of NOS1-derived NO in upper airway biology. We here hypothesized that nasal NO concentrations in CF patients are related to genotype variants in the NOS1 gene. Measurements of nasal NO concentration and pulmonary function were performed in 40 clinically stable CF patients. Genomic DNA from all patients was screened for an intronic AAT-repeat polymorphism in the NOS1 gene using polymerase chain reaction and simple sequence length polymorphism (SSLP) analysis. The allele size at that locus was significantly (P = 0.001) associated with upper airway NO. Mean (+/- SD) nasal NO concentrations were 40.5 +/- 5.2 ppb in CF patients (n = 12) with high repeat numbers (i.e., both alleles > or =12 repeats) and 72.6 +/- 7.4 ppb in patients (n = 28) with low repeat numbers (i.e., at least one allele <12 repeats). Furthermore, in the group of CF patients harboring NOS1 genotypes associated with low nasal NO, colonization of airways with P. aeruginosa was significantly more frequent than in patients with NOS1 genotypes associated high nasal NO concentrations (P = 0.0022). We conclude that (1) the variability in CF nasal NO levels are related to naturally occurring variants in the NOS1 gene, and (2) that nasal NOS1-derived NO affects the susceptibility of CF airways to infection with P. aeruginosa.
Finotto, S., M. F. Neurath, et al. (2002). "Development of spontaneous airway changes consistent with human asthma in mice lacking T-bet." Science 295(5553): 336-8.
Human asthma is associated with airway infiltration by T helper 2 (TH2) lymphocytes. We observed reduced expression of the TH1 transcription factor, T-bet, in T cells from airways of patients with asthma compared with that in T cells from airways of nonasthmatic patients, suggesting that loss of T-bet might be associated with asthma. Mice with a targeted deletion of the T-bet gene and severe combined immunodeficient mice receiving CD4+ cells from T-bet knockout mice spontaneously demonstrated multiple physiological and inflammatory features characteristic of asthma. Thus, T-bet deficiency, in the absence of allergen exposure, induces a murine phenotype reminiscent of both acute and chronic human asthma.
Drazen, J. M. (2002). "Allocating limited resources." N Engl J Med 346(5): 368.
Drazen, J. M. (2002). "Sleep apnea syndrome." N Engl J Med 346(6): 390.
Drazen, J. M. (2002). "The consumer and the learned intermediary in health care." N Engl J Med 346(7): 523-4.
Drazen, J. M. (2002). "Smallpox and bioterrorism." N Engl J Med 346(17): 1262-3.
Drazen, J. M. and G. D. Curfman (2002). "Financial associations of authors." N Engl J Med 346(24): 1901-2.
Drazen, J. M. and G. D. Curfman (2002). "On authors and contributors." N Engl J Med 347(1): 55.
Drazen, J. M. and G. D. Curfman (2002). "Retraction: Barbaro et Al. Incidence of dilated cardiomyopathy and detection of HIV in myocardial cells of HIV-positive patients. N Engl J Med 1998;339:1093-9." N Engl J Med 347(2): 140.
Drazen, J. M. and S. T. Weiss (2002). "Genetics: inherit the wheeze." Nature 418(6896): 383-4.
Drazen, J. M. (2002). "Who owns the data in clinical trial?" Sci Eng Ethics 8(3): 407-11.
Data gathered by investigators are used to test the validity of a specific scientific hypothesis. When the hypothesis relates to the biology of a disease or its treatment, then data sets may contain specific and identifiable medical information. Since the information in a clinical data set was gathered to test a specific hypothesis and there is usually a sponsor interested in the outcome, the issue of who owns the data is a critical one. In my opinion, data from both publicly and privately funded research should be made available, in a format that protects confidentiality and intellectual property rights, to interested and responsible parties within a reasonable period of time after publication.
Drazen, J. M. and A. M. Epstein (2002). "Rethinking medical training--the critical work ahead." N Engl J Med 347(16): 1271-2.
Drazen, J. M. (2002). "Institutions, contracts, and academic freedom." N Engl J Med 347(17): 1362-3.
Drazen, J. M. (2002). "A milestone in tuberculosis control." N Engl J Med 347(18): 1444.
Drazen, J. M. (2002). "Anti-leukotrienes as novel anti-inflammatory treatments in asthma." Adv Exp Med Biol 507: 217-21.
The anti-leukotrienes are effective asthma treatments. This observation demonstrates, by inference, that leukotrienes are important in the biology of asthma. The clinical data also indicate, however, that the leukotrienes are not the sole mediator of asthmatic responses as patients with asthma are totally free of airway obstruction or asthma symptoms when they are treated with these agents.
Deykin, A., A. F. Massaro, et al. (2002). "Exhaled nitric oxide as a diagnostic test for asthma: online versus offline techniques and effect of flow rate." Am J Respir Crit Care Med 165(12): 1597-601.
Measurement of the fraction of exhaled nitric oxide (FENO) has been proposed as a noninvasive assessment of asthmatic airway inflammation. The influence of the expiratory flow rate during the collection maneuver on the ability of FENO to discriminate healthy subjects from those with asthma is unknown. We compared online and offline measurement of FENO at different flow rates. FENO was collected with expiratory flows of 50-500 ml/second in 34 patients with asthma (PC(20) of less than 8 mg/ml) and 28 healthy subjects (PC(20) of more than 10 mg/ml) using offline collection techniques. In a subgroup of 18 individuals with asthma and 17 healthy subjects, we additionally measured FENO at multiple expiratory flow rates (47-250 ml/second) using online methods. FENO fell with an increasing expiratory flow rate; FENO was higher in subjects with asthma as compared with healthy subjects at each flow rate studied with both techniques (p < 0.001). Receiver operating characteristic (ROC) curves for the diagnosis of asthma indicated that FENO is a robust discriminator between individuals with asthma and healthy subjects (area under the ROC curves 0.79 +/- 0.06 to 0.86 +/- 0.06, p for significant discrimination < 0.0001). Neither expiratory flow rate nor collection technique (online versus offline) significantly altered this discriminatory capacity (area under the ROC curves = 0.84 +/- 0.07 with the slowest online method versus 0.80 +/- 0.07 with the fastest offline method, p = 0.46). These data indicate that the choice of expiratory flow rate and collection method can be based on practicality and patient comfort without compromising the utility of this test for asthma.
DeMeo, D. L., C. Lange, et al. (2002). "Univariate and multivariate family-based association analysis of the IL-13 ARG130GLN polymorphism in the Childhood Asthma Management Program." Genet Epidemiol 23(4): 335-48.
Interleukin 13 (IL-13) has been demonstrated to have a crucial role in animal models of allergy and asthma. In human case-control genetic-association studies, the Arg130Gln polymorphism has been associated with elevated total serum IgE and an asthma diagnosis in atopic and nonatopic individuals (Graves et al.  J. Allergy Clin. Immunol. 105:506-513; Heinzmann et al.  Hum. Mol. Genet. 9:549-559). To apply family-based association methods, we obtained DNA samples from 685 asthmatic children from 640 sibships and their parents in the Childhood Asthma Management Program (CAMP). Six hundred and sixty-six asthmatic children had complete phenotypic information and were used for this analysis. We performed quantitative association analysis using the transmission disequilibrium test (TDT) on 22 individual phenotypes and 5 grouped phenotypes relating to allergy, airway responsiveness, pulmonary function, bronchodilator responsiveness, and asthma severity, using genotypes at the Arg130Gln polymorphism of the IL-13 gene. A positive association was obtained between Arg130Gln and a grouped phenotype of allergy (consisting of the individual phenotypes of eosinophils, IgE, and positive skin tests), using FBAT-GEE, a multivariate extension of the family-based association test (Lange et al.  Biostatistics 1:1-15). The three phenotypes were then evaluated individually and revealed a significant association between total eosinophil count and the Arg130Gln locus; there was a trend for association between total IgE and the Arg130Gln polymorphism. The Arg130Gln polymorphism is associated with an elevated eosinophil count as well as with a grouped allergy phenotype, in children with mild to moderate asthma. No evidence for association was found between Arg130Gln and airway responsiveness, asthma diagnosis, or asthma severity.
Campion, E. W., K. Anderson, et al. (2002). "Advances in our electronic pages." N Engl J Med 346(5): 362.
Baron, R. M., L. J. Palmer, et al. (2002). "DNA sequence variants in epithelium-specific ETS-2 and ETS-3 are not associated with asthma." Am J Respir Crit Care Med 166(7): 927-32.
Epithelium-specific ETS-2 and ETS-3 are transcription factors that have been proposed as asthma candidate genes. To investigate the association of sequence variants in these genes with asthma, we conducted a case-control association analysis in a sample of 311 white subjects with asthma and 177 white subjects without asthma. Common polymorphisms in these genes were detected by sequencing DNA from 32 cell lines obtained from Coriel (Camden, NJ). Seven noncoding or synonymous single-nucleotide polymorphisms were detected: three in epithelium-specific ETS-2 and four in epithelium-specific ETS-3. Subjects were genotyped at all loci by mass spectroscopy. To ensure the suitability of our control subjects, we also genotyped subjects at 49 unlinked polymorphisms evenly distributed throughout the autosomes and found no evidence of population stratification. Logistic regression adjusted for age and sex suggested a weak association of one epithelium-specific ETS-2 polymorphism with asthma diagnosis (odds ratio = 1.89, 95% confidence interval = 1.13-3.18, p = 0.02). Total serum immunoglobulin E and FEV1 predicted levels were not associated with any of the polymorphisms. Extended haplotyping indicated linkage disequilibrium in these genes; however, no association or epistatic interaction was found. This study suggests that epithelium-specific ETS-2 and ETS-3 genes are unlikely to contain polymorphic loci that have a major impact on asthma susceptibility in our population.
Yu, H., B. Merchant, et al. (2001). "Automated detection of single nucleotide polymorphism in beta-2 adrenergic receptor gene using LCx(R)." Clin Chim Acta 308(1-2): 17-24.
Beta-2 adrenergic receptor (B2AR) agonists are the most widely prescribed rescue agents used in the treatment of asthma. Recent studies have indicated a relationship between a polymorphism at codon 16 of the B2AR gene, and the response to recurrent beta-agonist therapy. The B2AR polymorphism of interest involves a single nucleotide change from A to G, resulting in an amino acid change from Arginine (Arg) to Glycine (Gly). Clinical efforts to further investigate this relationship require an accurate, reliable and inexpensive method for detecting the polymorphism.In this study, we report an LCx(R) assay for the detection of a single nucleotide polymorphism at codon 16 of the beta-2 adrenergic receptor. This assay is capable of detecting patients harboring any of the three possible genotypes at this locus, namely, homozygous wild type, homozygous variant or heterozygous individuals with a single genomic DNA sample of 25-500 ng. It requires minimum hands-on time with automated detection. The assay would be suitable for use in research labs for screening of a large number of samples. We believe that this type of assay will facilitate research and clinical investigations in elucidating the association of SNPs with disease states, diagnosis, prognosis and treatment.
Wang, Z., C. Chen, et al. (2001). "Association of asthma with beta(2)-adrenergic receptor gene polymorphism and cigarette smoking." Am J Respir Crit Care Med 163(6): 1404-9.
Recent studies have suggested that two polymorphisms of the beta(2)-adrenergic receptor (beta(2)AR) gene at codons 16 (arginine to glycine) and 27 (glutamine to glutamate) affect an individual's airway responsiveness, or response to acute or chronic beta(2)-agonist therapy but are not risk factors for asthma. We hypothesize that there is an interaction effect on asthma between the beta(2)AR gene polymorphisms and cigarette smoking. A case-control study was conducted in 128 asthma cases and 136 control individuals identified from 10,014 studied subjects in rural Anqing, China. Allele-specific polymerase chain reaction (PCR) was used to genotype beta(2)AR gene polymorphisms. Multiple logistic regression was used to adjust for potential confounding factors. We found a marginally significant interaction between cigarette smoking and beta(2)AR-16 genotype after adjusting for important confounding factors (p = 0.06). Specifically, we found that compared with never-smoking Gly-16 homozygotes, those ever-smokers who are Arg-16 homozygotes had a significantly increased risk of asthma (odds ratio [OR] = 7.81; 95% confidence interval [CI]: 2.07 to 29.5). This association showed a clear dose-response relationship with the number of cigarettes smoked. However, there was no significant association of asthma with polymorphisms of the beta(2)AR at position 27 (OR = 1.38; 95% CI: 0.69 to 2.73). Our study suggests a gene-environment interaction between the Arg-16 genotype and ever cigarette smoking with respect to the susceptibility of an individual to asthma.
Tschumperlin, D. J. and J. M. Drazen (2001). "Mechanical stimuli to airway remodeling." Am J Respir Crit Care Med 164(10 Pt 2): S90-4.
The airway is exposed to a variety of mechanical stimuli, the most prominent of which is the acute compressive stress caused by bronchoconstriction. The folding of the airway wall into a rosette pattern during bronchoconstriction creates a complex stress field, with the highest stresses compressing the epithelial layer at the inner surface of the airway wall. The epithelial cells lining the airway possess the capacity to modulate the inflammatory environment of the airway wall, and produce factors that influence the recruitment, proliferation, and activity of fibroblasts and smooth muscle cells. A variety of in vitro studies have demonstrated that airway epithelial cells, along with lung fibroblasts and smooth muscle cells, are responsive to mechanical stimuli. Airway epithelial cells exposed to compressive stresses matched to those occurring in the constricted airway increase expression of genes relevant to airway remodeling, and increase the collagen synthesis of cocultured fibroblasts. These findings demonstrate that mechanical stress may contribute to the remodeling of the asthmatic airway.
Swartz, M. A., D. J. Tschumperlin, et al. (2001). "Mechanical stress is communicated between different cell types to elicit matrix remodeling." Proc Natl Acad Sci U S A 98(11): 6180-5.
Tissue remodeling often reflects alterations in local mechanical conditions and manifests as an integrated response among the different cell types that share, and thus cooperatively manage, an extracellular matrix. Here we examine how two different cell types, one that undergoes the stress and the other that primarily remodels the matrix, might communicate a mechanical stress by using airway cells as a representative in vitro system. Normal stress is imposed on bronchial epithelial cells in the presence of unstimulated lung fibroblasts. We show that (i) mechanical stress can be communicated from stressed to unstressed cells to elicit a remodeling response, and (ii) the integrated response of two cell types to mechanical stress mimics key features of airway remodeling seen in asthma: namely, an increase in production of fibronectin, collagen types III and V, and matrix metalloproteinase type 9 (MMP-9) (relative to tissue inhibitor of metalloproteinase-1, TIMP-1). These observations provide a paradigm to use in understanding the management of mechanical forces on the tissue level.
Steinbrook, R. and J. M. Drazen (2001). "AIDS--will the next 20 years be different?" N Engl J Med 344(23): 1781-2.
Silverman, E. S., G. T. De Sanctis, et al. (2001). "The transcription factor early growth-response factor 1 modulates tumor necrosis factor-alpha, immunoglobulin E, and airway responsiveness in mice." Am J Respir Crit Care Med 163(3 Pt 1): 778-85.
Early growth-response factor 1 (Egr-1) is a sequence-specific transcription factor that plays a regulatory role in the expression of many genes important in inflammation, cell growth, apoptosis, and the pathogenesis of disease. In vitro studies suggest that Egr-1 is capable of regulating the expression of tumor necrosis factor-alpha (TNF-alpha) and other genes involved in airway inflammation and reactivity following allergen stimulation. On the basis of these data, we hypothesized that in the absence of Egr-1, the TNF-alpha response and subsequent downstream inflammatory events that usually follow allergen challenge would be diminished. To test our hypothesis Egr-1 knock-out (KO) mice were examined in an ovalbumin (OVA)-induced model of airway inflammation and reactivity, and compared with identically treated wild-type (WT) control mice. In response to OVA sensitization and airway challenge, KO mice had diminished TNF-alpha mRNA and protein in the lungs and mast cells compared with WT mice. Interestingly, the KO mice had elevated IgE levels at baseline and after allergen challenge compared with WT mice. Furthermore, the airways of KO mice were hyporesponsive to methacholine challenge at baseline and after allergen challenge. These data indicate that Egr-1 modulates TNF-alpha, IgE, and airway responsiveness in mice.
Silverman, E. S., S. B. Liggett, et al. (2001). "The pharmacogenetics of asthma: a candidate gene approach." Pharmacogenomics J 1(1): 27-37.
Nakamura, H., A. D. Luster, et al. (2001). "Variant eotaxin: its effects on the asthma phenotype." J Allergy Clin Immunol 108(6): 946-53.
BACKGROUND: Eotaxin, a CC chemokine expressed in the asthmatic lung, has been associated with impaired lung function. The role of its variant form is unknown. OBJECTIVE: The purpose of this study was to detect the population frequency and effects of a known single-nucleotide polymorphism in the eotaxin gene in which a threonine residue (THR(23)) is substituted for the wild-type alanine (ALA(23)) at the 23rd amino acid at the terminus of the peptide leader sequence. METHODS: We measured eotaxin protein secretion in 293 cells transfected with expression vectors and in PBMCs obtained from individuals bearing the alternative forms of the gene. A case-control study of plasma eotaxin levels and eosinophil counts, a comparison of baseline lung function by genotype in a population of 806 subjects with asthma, and a comparison of the allele frequency with a nonasthmatic population were performed. RESULTS: Human 293 cells and PBMCs with THR(23) variant eotaxin secreted significantly less eotaxin protein than did ALA(23)-bearing cells. In the case-control study, THR(23)-THR(23) individuals had lower plasma levels of eotaxin (310 [240-350] vs 420 [270-700] pg/mL; P < .05) and eosinophil counts (120 [5-220] vs 190 [110-470] cells/microL; P < .05) than ALA(23)-ALA(23) subjects; heterozygous subjects had intermediate levels. Higher levels of lung function were associated with THR(23) eotaxin (percent of predicted FEV(1), 65% +/- 3.5% [THR(23)-THR(23)] vs 58% +/- 0.9% [THR(23)-ALA(23)] and 56% +/- 0.5% [ALA(23)-ALA(23)]; P < .05). CONCLUSION: The THR(23) variant is associated with both decreased eosinophil counts and higher levels of lung function in subjects with asthma.
Moy, M. L., E. Israel, et al. (2001). "Clinical predictors of health-related quality of life depend on asthma severity." Am J Respir Crit Care Med 163(4): 924-9.
The National Asthma Education and Prevention Program guidelines define asthma severity before treatment by lung function and symptoms. It has been assumed, but not demonstrated, that improvement in these measures would translate into improvement in health-related quality of life (HRQL). Because HRQL is an important outcome in asthma management, we asked what are the determinants of HRQL? To address this question, we retrospectively analyzed HRQL data, as measured by the Juniper Asthma Quality of Life Questionnaire, in subjects with mild versus moderate-severe asthma from two clinical trials. We examined whether these traditional clinical outcomes have different relationships to HRQL depending on asthma severity. We also assessed whether the relationship between clinical outcomes and HRQL in subjects with moderate-severe asthma would change when subjects improved to mild-moderate disease with controller medication treatment. Lung function was not an independent predictor or determinant of HRQL at any level of asthma severity, whereas intensity of shortness of breath predicted HRQL at all levels of asthma severity. Rescue beta-agonist use independently predicted HRQL in subjects with mild asthma, but not in those with moderate-severe asthma. In subjects with moderate-severe asthma who improved to mild-moderate disease with controller treatment, rescue beta-agonist use predicted HRQL. We conclude that the independent determinants of HRQL vary according to asthma severity and change with asthma treatment.
Leone, F. T., E. A. Mauger, et al. (2001). "The utility of peak flow, symptom scores, and beta-agonist use as outcome measures in asthma clinical research." Chest 119(4): 1027-33.
STUDY OBJECTIVES: Several methods of utilizing peak expiratory flow (PEF) and other markers of disease activity have been suggested as useful in the management of asthma. It remains unclear, however, as to which surrogate markers of disease status are discriminative indicators of treatment failure, suitable for use in clinical trials. DESIGN: We analyzed the operating characteristics of 66 surrogate markers of treatment failure using a receiver operating characteristic (ROC) curve analysis. PARTICIPANTS: Information regarding FEV(1), symptoms, beta(2)-agonist use, and PEF was available from 313 subjects previously enrolled in two Asthma Clinical Research Network trials, in which 71 treatment failures occurred (defined by a 20% fall in FEV(1) from baseline). INTERVENTIONS: None. MEASUREMENTS AND RESULTS: None of the measures had an acceptable ability to discriminate subjects with a > or % fall in FEV(1) from those without, regardless of the duration of the period of analysis or the criteria for test positivity employed. Areas under the ROC curves generated ranged from 0.51 to 0.79, but none were statistically superior. Sensitivity and specificity combinations were generally poor at all cutoff values; true-positive rates could not be raised without unacceptably elevating false-positive rates concurrently. CONCLUSIONS: Studies that seek to detect treatment failure defined by a significant fall in FEV(1) should not use such individual surrogate measures to estimate disease severity.
Lemanske, R. F., Jr., C. A. Sorkness, et al. (2001). "Inhaled corticosteroid reduction and elimination in patients with persistent asthma receiving salmeterol: a randomized controlled trial." Jama 285(20): 2594-603.
CONTEXT: Inhaled long-acting beta(2)-agonists improve asthma control when added to inhaled corticosteroid (ICS) therapy. OBJECTIVE: To determine whether ICS therapy can be reduced or eliminated in patients with persistent asthma after adding a long-acting beta(2)-agonist to their treatment regimen. DESIGN AND SETTING: A 24-week randomized, controlled, blinded, double-dummy, parallel-group trial conducted at 6 National Institutes of Health-sponsored, university-based ambulatory care centers from February 1997 through January 1999. PARTICIPANTS: One hundred seventy-five patients aged 12 through 65 years with persistent asthma that was suboptimally controlled during a 6-week run-in period of treatment with inhaled triamcinolone acetonide (400 microg twice per day). INTERVENTION: Patients continued triamcinolone therapy and were randomly assigned to receive add-on therapy with either placebo (placebo-minus group, n = 21) or salmeterol xinafoate, 42 microg twice per day (n = 154) for 2 weeks. The entire placebo-minus group was assigned and half of the salmeterol group (salmeterol-minus group) was randomly assigned to reduce by 50% (for 8 weeks) then eliminate (for 8 weeks) triamcinolone treatment. The other half of the salmeterol group (salmeterol-plus group) was randomly assigned to continue both salmeterol and triamcinolone for the remaining 16 weeks (active control group). MAIN OUTCOME MEASURE: Time to asthma treatment failure in patients receiving salmeterol. RESULTS: Treatment failure occurred in 8.3% (95% confidence interval [CI], 2%-15%) of the salmeterol-minus group 8 weeks after triamcinolone treatment was reduced compared with 2.8% (95% CI, 0%-7%) of the salmeterol-plus group during the same period. Treatment failure occurred in 46.3% (95% CI, 34%-59%) of the salmeterol-minus group 8 weeks after triamcinolone therapy was eliminated compared with 13.7% (95% CI, 5%-22%) of the salmeterol-plus group. The relative risk (95% CI) of treatment failure at the end of the triamcinolone elimination phase in the salmeterol-minus group was 4.3 (2.0-9.2) compared with the salmeterol-plus group (P<.001). CONCLUSIONS: Our results indicate that in patients with persistent asthma suboptimally controlled by triamcinolone therapy alone but whose asthma symptoms improve after addition of salmeterol, a substantial reduction (50%) in triamcinolone dose can occur without a significant loss of asthma control. However, total elimination of triamcinolone therapy results in a significant deterioration in asthma control and, therefore, cannot be recommended.
Lazarus, S. C., H. A. Boushey, et al. (2001). "Long-acting beta2-agonist monotherapy vs continued therapy with inhaled corticosteroids in patients with persistent asthma: a randomized controlled trial." Jama 285(20): 2583-93.
CONTEXT: Long-acting beta(2)-agonists are prescribed for patients with persistent asthma and are sometimes used without inhaled corticosteroids (ICSs). No evidence exists, however, to support their use as monotherapy in adults with persistent asthma. OBJECTIVE: To examine the effectiveness of salmeterol xinafoate, a long-acting beta(2)-agonist, as replacement therapy in patients whose asthma is well controlled by low-dose triamcinolone acetonide, an ICS. DESIGN AND SETTING: A 28-week, randomized, blinded, placebo-controlled, parallel group trial conducted at 6 National Institutes of Health-sponsored, university-based ambulatory care centers from February 1997 to January 1999. PARTICIPANTS: One hundred sixty-four patients aged 12 through 65 years with persistent asthma that was well controlled during a 6-week run-in period of treatment with inhaled triamcinolone (400 microg twice per day). INTERVENTIONS: Patients were randomly assigned to continue triamcinolone therapy (400 microg twice per day; n = 54) or switch to salmeterol (42 microg twice per day; n = 54) or to placebo (n = 56) for 16 weeks, after which all patients received placebo for an additional 6-week run-out period. MAIN OUTCOME MEASURES: Change in morning and evening peak expiratory flow (PEF), forced expiratory volume in 1 second (FEV(1)), self-assessed asthma symptom scores, rescue albuterol use, asthma-specific quality-of-life scores, treatment failure, asthma exacerbation, bronchial reactivity, and markers of airway inflammation, compared among the 3 treatment groups. RESULTS: During the 16-week randomized treatment period, no significant differences between the salmeterol and triamcinolone groups were observed for conventional outcomes of clinical studies of asthma therapy-morning PEF, evening PEF, asthma symptom scores, rescue albuterol sulfate use, or quality of life. Both active treatments were superior to placebo. However, the salmeterol group had more treatment failures than the triamcinolone group (13/54 [24%] vs 3/54 [6%]; P =.004), as well as more asthma exacerbations (11/54 [20%] vs 4/54 [7%]; P =.04), greater increases in median (interquartile range) sputum eosinophils (2.4% [0.0% to 10.6%] vs -0.1% [-0.7% to 0.3%]; P<.001), eosinophil cationic protein (71 [-2 to 430] U/L vs -4 [-31 to 56] U/L; P =.005), and tryptase (3.1 [2.1 to 7.6] ng/mL vs 0.0 [0.0 to 0.7] ng/mL; P<.001). The duration of benefit when patients were switched from active treatment to placebo after 22 weeks of randomized treatment was not significantly longer in the triamcinolone group than in the salmeterol group. CONCLUSIONS: Patients with persistent asthma well controlled by low doses of triamcinolone cannot be switched to salmeterol monotherapy without risk of clinically significant loss of asthma control.
Israel, E., J. M. Drazen, et al. (2001). "Effect of polymorphism of the beta(2)-adrenergic receptor on response to regular use of albuterol in asthma." Int Arch Allergy Immunol 124(1-3): 183-6.
BACKGROUND: Regular use of inhaled beta-adrenergic agonists may have adverse effects in some asthma patients. Polymorphisms of the beta(2)-adrenergic receptor (beta(2)-AR) can affect its regulation; however, results of smaller studies of the effects of such polymorphisms on response to beta-agonist therapy have been inconsistent. METHODS: We examined the possible effects of polymorphisms at codons 16 (beta(2)-AR-16) and 27 (beta(2)-AR-27) on response to albuterol by genotyping 190 asthmatics who had participated in a trial of regular versus as-needed albuterol use. RESULTS: During the 16-week treatment period, patients homozygous for arginine (Arg/Arg) at beta(2)-AR-16 who used albuterol regularly had a small decline in morning peak expiratory flow (AM PEF). This effect was magnified during a 4-week run-out period, when all patients returned to as-needed albuterol only. By the end of the study, Arg/Arg subjects who had used albuterol regularly had an AM PEF 30.5 +/- 12.1 liters/min lower (p = 0.012) than Arg/Arg patients who had used albuterol as needed only. Subjects homozygous for glycine at beta(2)-AR-16 showed no such decline. Evening PEF also declined in the Arg/Arg regular but not in as-need albuterol users. No significant differences between regular and as-needed treatment were associated with polymorphisms at beta(2)-AR-27. CONCLUSIONS: Polymorphisms of the beta(2)-AR may influence airway responses to regular inhaled beta-agonist treatment.
Huang, C., G. T. De Sanctis, et al. (2001). "Evaluation of the substrate specificity of human mast cell tryptase beta I and demonstration of its importance in bacterial infections of the lung." J Biol Chem 276(28): 26276-84.
Human pulmonary mast cells (MCs) express tryptases alpha and beta I, and both granule serine proteases are exocytosed during inflammatory events. Recombinant forms of these tryptases were generated for the first time to evaluate their substrate specificities at the biochemical level and then to address their physiologic roles in pulmonary inflammation. Analysis of a tryptase-specific, phage display peptide library revealed that tryptase beta I prefers to cleave peptides with 1 or more Pro residues flanked by 2 positively charged residues. Although recombinant tryptase beta I was unable to activate cultured cells that express different types of protease-activated receptors, the numbers of neutrophils increased >100-fold when enzymatically active tryptase beta I was instilled into the lungs of mice. In contrast, the numbers of lymphocytes and eosinophils in the airspaces did not change significantly. More important, the tryptase beta I-treated mice exhibited normal airway responsiveness. Neutrophils did not extravasate into the lungs of tryptase alpha-treated mice. Thus, this is the first study to demonstrate that the two nearly identical human MC tryptases are functionally distinct in vivo. When MC-deficient W/W(v) mice were given enzymatically active tryptase beta I or its inactive zymogen before pulmonary infection with Klebsiella pneumoniae, tryptase beta I-treated W/W(v) mice had fewer viable bacteria in their lungs relative to zymogen-treated W/W(v) mice. Because neutrophils are required to combat bacterial infections, human tryptase beta I plays a critical role in the antibacterial host defenses of the lung by recruiting neutrophils in a manner that does not alter airway reactivity.
Forand, P. E., S. J. Kunselman, et al. (2001). "Genetic analysis in the Asthma Clinical Research Network." Control Clin Trials 22(6 Suppl): 196S-206S.
Because there is reason to believe that genetic variants could account for different treatment responses in subjects with asthma, it is important to collect blood for genetic-analysis purposes when conducting clinical trials in asthma. This article describes issues related to maintaining subject confidentiality, tracking and shipping blood samples, quality control procedures at the laboratory performing the genotyping, and necessary data verification checks when implementing the genetic-analysis database for the Asthma Clinical Research Network.
Fahy, J. V., H. A. Boushey, et al. (2001). "Safety and reproducibility of sputum induction in asthmatic subjects in a multicenter study." Am J Respir Crit Care Med 163(6): 1470-5.
The safety of sputum induction and the reproducibility of measurements in induced sputum in multicenter studies is unknown. We examined the safety of sputum induction in a two-visit, six-center study in 79 subjects with moderate to severe asthma (mean +/- SD FEV(1) 71 +/- 12% predicted, 67% taking inhaled corticosteroids). In addition, we compared the reproducibility of markers of inflammation in induced sputum with the reproducibility of the FEV(1) and the methacholine PC(20). The FEV(1) decreased > or = 20% from the postbronchodilator baseline in 14% of all subjects and in 25% of subjects whose initial prebronchodilator baseline was 40 to 60% of predicted. All subjects responded promptly to additional albuterol treatment, and no subject developed refractory bronchoconstriction requiring treatment other than reversal of bronchospasm in the study laboratory. The reproducibility of measurements of the eosinophil percentage, eosinophil cationic protein, tryptase, and methacholine PC(20) were similar (concordance correlation coefficients of 0.74, 0.81, 0.79, and 0.74, respectively), without any significant among-center effect. We conclude that sputum induction can be performed safely in subjects with moderate to severe asthma in multicenter clinical trials when carried out under carefully monitored conditions. Importantly, we demonstrate that measurement of markers of inflammation in induced sputum is as reproducible as methacholine PC(20) and should prove useful in the assessment of airway inflammation in multicenter clinical trials.
Epstein, A. M., J. M. Drazen, et al. (2001). "Health policy 2001--a new series." N Engl J Med 344(9): 673.
Drazen, J. M. (2001). "Surgery for emphysema--not for everyone." N Engl J Med 345(15): 1126-7.
Davidoff, F., C. D. DeAngelis, et al. (2001). "Sponsorship, authorship, and accountability." N Engl J Med 345(11): 825-6; discussion 826-7.
Davidoff, F., C. D. DeAngelis, et al. (2001). "Sponsorship, authorship, and accountability." Jama 286(10): 1232-4.
Davidoff, F., C. D. DeAngelis, et al. (2001). "Sponsorship, authorship, and accountability." Ann Intern Med 135(6): 463-6.
Davidoff, F., C. D. DeAngelis, et al. (2001). "Sponsorship, authorship, and accountability." Lancet 358(9285): 854-6.
Davidoff, F., C. D. Deangelis, et al. (2001). "Sponsorship, authorship, and accountability." Ugeskr Laeger 163(37): 4983-5.
Davidoff, F., C. D. DeAngelis, et al. (2001). "Sponsorship, authorship and accountability." Cmaj 165(6): 786-8.
Davidoff, F., C. D. DeAngelis, et al. (2001). "Sponsorship, authorship and accountability." Med J Aust 175(6): 294-6.
Davidoff, F., C. D. DeAngelis, et al. (2001). "Sponsorship, authorship, and accountability." Arch Otolaryngol Head Neck Surg 127(10): 1178-80.
Davidoff, F., C. D. DeAngelis, et al. (2001). "[Sponsorship, authorship and accountability]." Rev Esp Cardiol 54(11): 1247-50.
Davidoff, F., C. D. DeAngelis, et al. (2001). "Sponsorship, authorship and accountability." Lakartidningen 98(43): 4694-6.
Davidoff, F., C. D. DeAngelis, et al. (2001). "Sponsorship, authorship, and accountability." Obstet Gynecol 98(6): 1143-6.
Davidoff, F., C. D. DeAngelis, et al. (2001). "[Sponsorship, authorship and accountability]." Tidsskr Nor Laegeforen 121(21): 2531-2.
Curfman, G. D. and J. M. Drazen (2001). "Too close to call." N Engl J Med 345(11): 832.
Chinchilli, V. M., J. M. Drazen, et al. (2001). "The clinical trials in the initial five-year award period of the Asthma Clinical Research Network." Control Clin Trials 22(6 Suppl): 126S-34S.
During its first years of existence, the Asthma Clinical Research Network initiated four major clinical trials and one pilot clinical trial. The objective of this article is to describe briefly the specific aims, design, and conduct of those five trials.
Barr, R. G., D. M. Cooper, et al. (2001). "Beta(2)-adrenoceptor polymorphism and body mass index are associated with adult-onset asthma in sedentary but not active women." Chest 120(5): 1474-9.
STUDY OBJECTIVE: Beta(2)-adrenoceptor Gly16 polymorphism has been associated with asthma severity and beta(2)-adrenoceptor receptor downregulation, but not with the diagnosis of asthma. Glu27 polymorphism may limit beta(2)-adrenoceptor downregulation and predict body mass index (BMI), particularly among sedentary persons. In addition, BMI predicts asthma. We hypothesized that these DNA sequence variants predict adult-onset asthma only in sedentary women. DESIGN: Nested case-control study. SETTING: Nurses' Health Study, a large, prospective cohort study with participants throughout the United States. PARTICIPANTS: Among lifelong nonsmokers, 171 women with adult-onset, medication-requiring asthma and 137 age-matched control subjects. MEASUREMENTS: Physical activity and BMI were self-reported by previously validated questionnaire items. Genomic DNA was obtained from buccal brushings collected via first-class mail. RESULTS: Of 76 sedentary women, the adjusted odds ratios of Gly16 allele were 7.4 (p = 0.047) for asthma and 13.8 (p = 0.02) for steroid-requiring asthma. No similar associations were observed among 232 active women (p = 0.91). Sedentary individuals with both Gly16 and Glu27 alleles had a less elevated risk for asthma. BMI was associated with asthma and Glu27 allele among sedentary women. CONCLUSION: This exploratory analysis suggests an important gene/environment interaction for asthma involving physical activity level. Further study in larger populations is warranted to confirm if sedentary lifestyle unmasks a genetic risk for asthma.
Baron, R., E. S. Silverman, et al. (2001). "DNA sequence variants of the platelet-derived growth factor A-chain gene." Clin Exp Allergy 31(10): 1501-8.
BACKGROUND: Platelet-derived growth factor A-chain (PDGF-A) is a potent connective tissue mitogen implicated in lung growth and development. PDGF-A may have a role in asthma through effects on fibroblasts and bronchial smooth muscle cells. OBJECTIVE: To test the hypothesis that there exist variations in the PDGF-A gene associated with the asthma phenotype. METHODS: We screened genomic DNA from normal and asthmatic subjects using single-stranded conformational polymorphism (SSCP) for mutations in the promoter and all seven exons of the gene. RESULTS: Four transition polymorphisms (three novel) were identified: one each in exons 3 and 4 (overall population allele frequencies 0.18 and 0.02, respectively) which did not alter the protein sequence, one in exon 4 (frequency 0.005) which resulted in a valine to isoleucine substitution, and one in intron 5 (frequency 0.5). The intron 5-sequence variant is close to the 3' end of exon 5 but does not appear to affect alternative splicing of PDGF-A exon 6 RNA. The frequencies of the polymorphisms in exons 3 and intron 5 did not differ between the asthmatic and non-asthmatic subjects, but there was a significant frequency difference between Caucasian and African-American subjects for each of these polymorphisms (P = 0.03 and 0.003, respectively). CONCLUSION: No association was found between the sequence variants in the PDGF-A gene and the development of asthma. However, the allele frequency of some of the sequence variants differed between the Caucasian and African-American subjects.
Wechsler, M. E., D. Finn, et al. (2000). "Churg-Strauss syndrome in patients receiving montelukast as treatment for asthma." Chest 117(3): 708-13.
STUDY OBJECTIVES: We previously reported eight patients who developed Churg-Strauss syndrome in association with zafirlukast treatment for asthma and postulated that the syndrome resulted from unmasking of a previously existing condition due to corticosteroid withdrawal and not from a direct drug effect. The availability of montelukast, a new leukotriene receptor antagonist with a different molecular structure, permitted us to test this hypothesis. Our goals were to ascertain whether the Churg-Strauss syndrome developed in patients taking montelukast and other novel asthma medications, and to describe potential mechanisms for the syndrome. DESIGN: Case series. SETTING: Outpatient and hospital practices of pulmonologists in the United States and Belgium. PATIENTS: Four adults (one man, three women) who received montelukast as treatment for asthma; two women who received salmeterol/fluticasone therapy, but not montelukast. RESULTS: Churg-Strauss syndrome developed in the four asthmatic patients who received montelukast. In each case, there was a long history of difficult-to-control asthma characterized by multiple exacerbations that had required frequent courses of oral systemic corticosteroids or high doses of inhaled corticosteroids for control. Two other asthmatics who received fluticasone and salmeterol but not montelukast therapy developed the same syndrome with tapering doses of oral or high doses of inhaled corticosteroids. CONCLUSIONS: The occurrence of Churg-Strauss syndrome in asthmatic patients receiving leukotriene modifiers appears to be related to unmasking of an underlying vasculitic syndrome that is initially clinically recognized as moderate to severe asthma and treated with corticosteroids. Montelukast does not appear to directly cause the syndrome in these patients.
Wechsler, M. E., H. Grasemann, et al. (2000). "Exhaled nitric oxide in patients with asthma: association with NOS1 genotype." Am J Respir Crit Care Med 162(6): 2043-7.
An increased concentration of nitric oxide (NO) in exhaled air (FENO) is now recognized as a critical component of the asthmatic phenotype. When we identified patients with asthma on the basis of a standard case definition alone, we found that they were remarkably heterogeneous with respect to their FENO. However, when we included genotype at a prominent asthma candidate gene (i.e., NOS1) in the case definition, and determined the number of AAT repeats in intron 20, we identified a remarkably homogeneous cohort of patients with respect to FENO. Both mean FENO (p = 0.00008) and variability around the mean (p = 0.000002) were significantly lower in asthmatic individuals with a high number (> or = 12) of AAT repeats at this locus than in those with fewer repeats. These data provide a biologically tenable link between genotype at a candidate gene in a region of linkage, NOS1, and an important component of the asthmatic phenotype, FENO. We show that addition of NOS1 genotype to the case definition of asthma allows the identification of a uniform cohort of patients, with respect to FENO, that would have been indistinguishable by other physiologic criteria. Our isolation of this homogeneous cohort of patients ties together the well-established associations among asthma, increased concentrations of NO in the exhaled air of asthmatic individuals, and variations of trinucleotide repeat sequences as identified in several neurologic conditions.
Van Sambeek, R., D. D. Stevenson, et al. (2000). "5' flanking region polymorphism of the gene encoding leukotriene C4 synthase does not correlate with the aspirin-intolerant asthma phenotype in the United States." J Allergy Clin Immunol 106(1 Pt 1): 72-6.
BACKGROUND: Approximately 10% of patients with asthma have a distinct clinical entity in which their symptoms are exacerbated by aspirin and most other nonsteroidal anti-inflammatory agents. These individuals typically have significant basal overproduction of cysteinyl leukotrienes, and within their biosynthetic pathway, the terminal enzyme, leukotriene C(4) synthase (LTC(4)S), is significantly overexpressed. A single nucleotide polymorphism consisting of an adenine (A) to cytosine (C) transversion -444 nucleotides upstream of the ATG translation start site in the LTC(4)S gene has been associated with a relative risk of 3.89 for the aspirin-intolerant phenotype in Polish patients. OBJECTIVE: These studies were undertaken to further investigate the functional effect of this allele in LTC(4)S gene expression and subsequently to determine whether an association between the presence of this polymorphism and aspirin-intolerant asthma existed within patients of the United States. METHODS: Functionality of the C-444 allele was assessed by using promoter-reporter constructs and transient transfection assays in the THP-1 monocytic cell line. Genotyping was performed on 137 unaffected control subjects, 33 patients with aspirin-tolerant asthma, and 61 patients with aspirin-intolerant asthma from the United States. RESULTS: Promoter-reporter constructs containing the C-444 allele revealed no significant upregulatory or downregulatory effects in the transcription of the LTC(4)S gene. The LTC(4)S genotype distribution was consistent with the Hardy-Weinberg equilibrium in patients with aspirin-tolerant asthma and unaffected control subjects but not in patients with aspirin-intolerant asthma; however, the distributions were not significantly different among the phenotype groups. CONCLUSIONS: Our data demonstrate that the C-444 allele in the LTC4S gene is not statistically different among patients with the aspirin-intolerant asthmatic phenotype, patients with the aspirin-tolerant asthmatic phenotype, and unaffected control subjects in the United States. This finding, along with the lack of functionality of this polymorphism, suggest that it is not related to a specific asthma phenotype and may represent a population-stratified polymorphism within patients of eastern European descent.
Taylor, D. R., J. M. Drazen, et al. (2000). "Asthma exacerbations during long term beta agonist use: influence of beta(2) adrenoceptor polymorphism." Thorax 55(9): 762-7.
BACKGROUND: Polymorphisms of the beta(2) adrenoceptor influence receptor function in vitro and asthma phenotypes in vivo. However, their importance in determining responses to inhaled beta agonist treatment has not been clearly defined. METHODS: In a retrospective analysis of previously published data we have examined relationships between polymorphisms at codons 16 and 27 of the beta(2) adrenoceptor and clinical outcomes in a randomised, placebo controlled, crossover trial of regularly scheduled salbutamol and salmeterol in 115 patients with mild to moderate asthma. Genotyping was obtained for positions 16 and 27 in 108 and 107 patients, respectively. For position 16, 17 patients (16%) were homozygous Arg-Arg, 40 (37%) were heterozygous Arg-Gly, and 51 (47%) were homozygous Gly-Gly. RESULTS: Within the homozygous Arg-16 group major exacerbations were more frequent during salbutamol treatment than with placebo (1.91 (95% CI 1.07 to 3.12) per year versus 0.81 (95% CI 0.28 to 1.66) per year; p = 0.005). No significant treatment related differences occurred for heterozygous Arg-Gly patients (salbutamol 0.11 (95% CI 0.01 to 0.40), placebo 0.54 (95% CI 0.26 to 1.00) exacerbations per year) or homozygous Gly-16 patients (salbutamol 0.38 (95% CI 0.17 to 0.73), placebo 0.30 (95% CI 0.12 to 0.61) exacerbations per year). No adverse changes occurred for any position 16 subgroup with salmeterol. There was no significant relationship between position 27 genotypes and treatment related outcomes. CONCLUSION: Homozygous Arg-16 patients are susceptible to clinically important increases in asthma exacerbations during chronic dosing with the short acting beta(2) agonist salbutamol.
Silverman, E. S. and J. M. Drazen (2000). "Genetic variations in the 5-lipoxygenase core promoter. Description and functional implications." Am J Respir Crit Care Med 161(2 Pt 2): S77-80.
Silverman, E. K., F. E. Speizer, et al. (2000). "Familial aggregation of severe, early-onset COPD : candidate gene approaches." Chest 117(5 Suppl 1): 273S-4S.
Silverman, E. K., S. T. Weiss, et al. (2000). "Gender-related differences in severe, early-onset chronic obstructive pulmonary disease." Am J Respir Crit Care Med 162(6): 2152-8.
Men have higher prevalence rates of chronic obstructive pulmonary disease (COPD) than women, which has been attributed to the historically higher rates of cigarette smoking in males. However, the increased rates of cigarette smoking in females within the last several decades have been associated with steadily increasing rates of COPD in women. As part of a study of the genetics of severe, early-onset COPD, we assembled a group of 84 probands with severe, early-onset COPD (without severe alpha(1)-antitrypsin deficiency) and 348 of their first-degree relatives. We found a markedly elevated prevalence (71.4%) of females among the early-onset COPD probands. Among the entire group of first-degree relatives of early-onset COPD probands, univariate analysis demonstrated similar spirometric values and bronchodilator responsiveness in males and females; however, among current or ex-smokers, female first-degree relatives had significantly lower FEV(1)/ FVC (81.4 +/- 17.2% in females versus 87.0 +/- 12.9% in males, p = 0.009) and significantly greater bronchodilator responsiveness (expressed as percentage of baseline FEV(1)) (7.7 +/- 9.4% pred in females versus 4.1 +/- 6.4% pred in males, p = 0.002). Female smoking first-degree relatives were significantly more likely to demonstrate profound reductions in FEV(1) (< 40% pred) than male smoking first-degree relatives (p = 0. 03). Multivariate analysis, performed with generalized estimating equations, demonstrated that current or ex-smoking female first-degree relatives had significantly greater risk of FEV(1) < 80% pred (OR 1.91, 95% CI 1.03- 3.54), FEV(1) < 40% pred (OR 3.56, 95% CI 1.08-11.71), and bronchodilator response greater than 10% of baseline FEV(1) (OR 4.74, 95% CI 1.91-11.75). These results suggest that women may be more susceptible to the development of severe COPD.
Ressler, B., R. T. Lee, et al. (2000). "Molecular responses of rat tracheal epithelial cells to transmembrane pressure." Am J Physiol Lung Cell Mol Physiol 278(6): L1264-72.
Smooth muscle constriction in asthma causes the airway to buckle into a rosette pattern, folding the epithelium into deep crevasses. The epithelial cells in these folds are pushed up against each other and thereby experience compressive stresses. To study the epithelial cell response to compressive stress, we subjected primary cultures of rat tracheal epithelial cells to constant elevated pressures on their apical surface (i.e., a transmembrane pressure) and examined changes in the expression of genes that are important for extracellular matrix production and maintenance of smooth muscle activation. Northern blot analysis of RNA extracted from cells subjected to transmembrane pressure showed induction of early growth response-1 (Egr-1), endothelin-1, and transforming growth factor-beta1 in a pressure-dependent and time-dependent manner. Increases in Egr-1 protein were detected by immunohistochemistry. Our results demonstrate that airway epithelial cells respond rapidly to compressive stresses. Potential transduction mechanisms of transmembrane pressure were also investigated.
Moore, P. E., J. D. Laporte, et al. (2000). "Polymorphism of the beta(2)-adrenergic receptor gene and desensitization in human airway smooth muscle." Am J Respir Crit Care Med 162(6): 2117-24.
We examined the influence of two common polymorphic forms of the beta(2)-adrenergic receptor (beta(2)AR): the Gly16 and Glu27 alleles, on acute and long-term beta(2)AR desensitization in human airway smooth muscle (HASM) cells. In cells from 15 individuals, considered without respect to genotype, pretreatment with Isoproterenol (ISO) at 10(-7) M for 1 h or 24 h caused approximately 25% and 64% decreases in the ability of subsequent ISO (10(-6) M) stimulation to reduce HASM cell stiffness as measured by magnetic twisting cytometry. Similar results were obtained with ISO-induced cyclic adenosine monophosphate (cAMP) as the outcome indicator. Data were then stratified post hoc by genotype. Cells containing at least one Glu27 allele (equivalent to presence of the Gly16Glu27 haplotype) showed significantly greater acute desensitization than did cells with no Glu27 allele, whether ISO-induced cell stiffness (34% versus 19%, p < 0.03) or cAMP formation (58% versus 11%, p < 0.02) was measured. Likewise, cells with any Glu27 allele showed greater long-term desensitization of cell stiffness and cAMP formation responses than did cells without the Glu27 allele. The distribution of genotypes limited direct conclusions about the influence of the Gly16 allele. However, presence of the Gly16Gln27 haplotype was associated with less acute and long-term desensitization of ISO-induced cAMP formation than was seen in cells without the Gly16Gln27 haplotype (14% versus 47%, p < 0.09 for short-term desensitization; 32% versus 84%, p < 0.01 for long-term desensitization), suggesting that the influence of Glu27 is not through its association with Gly16. The Glu27 allele was in strong linkage disequilibrium with the Arg19 allele, a polymorphic form of the beta(2)AR upstream peptide of the 5'-leader cistron of the beta(2)AR, and this polymorphism in the beta(2)AR 5'-flanking region may explain the effects of the Glu27 allele. Cells with any Arg19 allele showed significantly greater acute and long-term desensitization of ISO-induced cAMP formation than did cells without the Arg19 allele (54% versus 2%, p < 0.01 for short-term desensitization; 73% versus 35%, p < 0.05 for long-term desensitization). Similar results were obtained for ISO-induced changes in cell stiffness. Thus, the presence of the Glu27 allele is associated with increased acute and long-term desensitization in HASM.
MacLean, J. A., G. T. De Sanctis, et al. (2000). "CC chemokine receptor-2 is not essential for the development of antigen-induced pulmonary eosinophilia and airway hyperresponsiveness." J Immunol 165(11): 6568-75.
Monocyte chemoattractant proteins-1 and -5 have been implicated as important mediators of allergic pulmonary inflammation in murine models of asthma. The only identified receptor for these two chemokines to date is the CCR2. To study the role of CCR2 in a murine model of Ag-induced asthma, we compared the pathologic and physiological responses of CCR2(-/-) mice with those of wild-type (WT) littermates following immunization and challenge with OVA. OVA-immunized/OVA-challenged (OVA/OVA) WT and CCR2(-/-) mice developed significant increases in total cells recovered by bronchoalveolar lavage (BAL) compared with their respective OVA-immunized/PBS-challenged (OVA/PBS) control groups. There were no significant differences in BAL cell counts and differentials (i.e., macrophages, PMNs, lymphocytes, and eosinophils) between OVA/OVA WT and CCR2(-/-) mice. Serologic evaluation revealed no significant difference in total IgE and OVA-specific IgE between OVA/OVA WT mice and CCR2(-/-) mice. Lung mRNA expression and BAL cytokine protein levels of IL-4, IL-5, and IFN-gamma were also similar in WT and CCR2(-/-) mice. Finally, OVA/OVA CCR2(-/-) mice developed increased airway hyper-responsiveness to a degree similar to that in WT mice. We conclude that following repeated airway challenges with Ag in sensitized mice, the development of Th2 responses (elevated IgE, pulmonary eosinophilia, and lung cytokine levels of IL-4 and IL5) and the development of airway hyper-responsiveness are not diminished by a deficiency in CCR2.
Israel, E., J. M. Drazen, et al. (2000). "The effect of polymorphisms of the beta(2)-adrenergic receptor on the response to regular use of albuterol in asthma." Am J Respir Crit Care Med 162(1): 75-80.
Inhaled beta-adrenergic agonists are the most commonly used medications for the treatment of asthma although there is evidence that regular use may produce adverse effects in some patients. Polymorphisms of the beta(2)-adrenergic receptor (beta(2)-AR) can affect regulation of the receptor. Smaller studies examining the effects of such polymorphisms on the response to beta-agonist therapy have produced inconsistent results. We examined whether polymorphisms at codon 16 (beta(2)-AR-16) and codon 27 (beta(2)-AR-27) of the beta(2)-AR might affect the response to regular versus as-needed use of albuterol by genotyping the 190 asthmatics who had participated in a trial examining the effects of regular versus as needed albuterol use. During the 16-wk treatment period there was a small decline in morning peak expiratory flow in patients homozygous for arginine at B(2)-AR-16 (Arg/Arg) who used albuterol regularly. This effect was magnified during a 4-wk run out period, during which all patients returned to using as-needed albuterol, so that by the end of the study Arg Arg patients who had regularly used albuterol had a morning peak expiratory flow 30. 5 +/- 12.1 L/min lower (p = 0.012) than Arg/Arg patients who had used albuterol on an as needed basis. There was no decline in peak flow with regular use of albuterol in patients who were homozygous for glycine at beta(2)-AR-16. Evening peak expiratory flow also declined in the Arg/Arg patients who used albuterol regularly but not in those who used albuterol on an as-needed basis. No significant differences in outcomes between regular and as-needed treatment were associated with polymorphisms at position 27 of the beta(2)-AR. No other differences in asthma outcomes that we investigated occurred in relation to these beta(2)-AR polymorphisms. Polymorphisms of the beta(2)-AR may influence airway responses to regular inhaled beta-agonist treatment.
Grasemann, H., C. N. Yandava, et al. (2000). "A neuronal NO synthase (NOS1) gene polymorphism is associated with asthma." Biochem Biophys Res Commun 272(2): 391-4.
Recent family-based studies have revealed evidence for linkage of chromosomal region 12q to both asthma and high total serum immunoglobulin E (IgE) levels. Among the candidate genes in this region for asthma is neuronal nitric oxide synthase (NOS1). We sought a genetic association between a polymorphism in the NOS1 gene and the diagnosis of asthma, using a case-control design. Frequencies for allele 17 and 18 of a CA repeat in exon 29 of the NOS1 gene were significantly different between 490 asthmatic and 350 control subjects. Allele 17 was more common in the asthmatics (0.83 vs 0.76, or 1.49 [95% CI 1.17-1.90], P = 0.013) while allele 18 was less common in the asthmatics (0.06 vs 0.12, or 0.49 [95% CI 0.34-0. 69], P = 0.0004). To confirm these results we genotyped an additional 1131 control subjects and found the frequencies of alleles 17 and 18 to be virtually identical to those ascertained in our original control subjects. Total serum IgE was not associated with any allele of the polymorphism. These findings provide support, from case-control association analysis, for NOS1 as a candidate gene for asthma.
Grasemann, H., N. Knauer, et al. (2000). "Airway nitric oxide levels in cystic fibrosis patients are related to a polymorphism in the neuronal nitric oxide synthase gene." Am J Respir Crit Care Med 162(6): 2172-6.
Patients with cystic fibrosis (CF) have decreased concentrations of expired nitric oxide (FENO) as compared with healthy individuals. A number of factors, including viscous mucus as a diffusion barrier for airway NO, consumption of NO by bacterial enzymes, and decreased NO production have been hypothesized to account for these low levels of FENO. We examined the relationship between the size of an AAT repeat polymorphism in intron 20 of the NOS1 gene and FENO in 75 patients with CF. Mean FENO was significantly (p = 0.027) lower in CF patients who harbored two alleles with a high number of repeats (>/= 12) than in those who harbored alleles with fewer repeats at this locus (4.0 +/- 0.8 [mean +/- SEM] ppb versus 6.4 +/- 0.9 ppb). Colonization of the airways with Pseudomonas aeruginosa was significantly (p = 0.0358) more common in CF patients with high numbers of AAT repeats in the NOS1 gene. Significant differences between NOS1 genotypes were also observed among patients homozygous for the cystic fibrosis transmembrane regulator delta F508 mutation for FENO (2.3 +/- 0.4 ppb versus 5.3 +/- 0.7 ppb, p = 0.0006), and this was also true for colonization of the airways with P. aeruginosa (p = 0.0147) and Aspergillus fumigatus (p = 0.0221). These data provide evidence that the NOS1 gene is not only associated with the variability of FENO, but also with P. aeruginosa colonization of airways in CF patients.
Drazen, J. M. (2000). "Looking forward to serving you every week." N Engl J Med 343(1): 57-8.
Drazen, J. M., G. W. Bush, et al. (2000). "The Republican and Democratic candidates speak on health care." N Engl J Med 343(16): 1184-9.
Drazen, J. M. and G. Koski (2000). "To protect those who serve." N Engl J Med 343(22): 1643-5.
Drazen, J. M., E. K. Silverman, et al. (2000). "Heterogeneity of therapeutic responses in asthma." Br Med Bull 56(4): 1054-70.
Asthma is a complex clinical syndrome with multiple genetic and environmental factors contributing to its phenotypic expression. This aetiological heterogeneity adds to the complexity when addressing variation in the response to anti-asthma treatment. Currently, there are three main lines of treatment available: (i) inhaled glucocorticoids which have multiple mechanisms of action; (ii) beta 2-agonists which are very effective bronchodilators and act predominantly on airway smooth muscle; and (iii) cysteinyl-leukotriene inhibitors. Analysis of the repeatability (r) of the treatment response, defined as the fraction of the total population variance which results from among-individual differences, shows values of r between 60-80% indicating that a substantial fraction of the variance of the treatment response could be genetic in nature. Among the sources of variability that could contribute to the observed heterogeneity in the response to treatment are the degree of underlying inflammation, such as in glucocorticoid resistance, and polymorphisms in the genes encoding the drug target, such as beta 2-adrenoceptor and 5-lipoxygenase.
Deykin, A., A. F. Massaro, et al. (2000). "Exhaled nitric oxide following repeated spirometry or repeated plethysmography in healthy individuals." Am J Respir Crit Care Med 161(4 Pt 1): 1237-40.
Subjects with asthma have higher concentrations of exhaled nitric oxide (NO) than normal individuals. It has been demonstrated that in asthmatics, repeated FVC maneuvers reduce NO. Although the cause of this phenomenon is not known, it has been hypothesized that deep breaths associated with FVC maneuvers reduce exhaled NO by affecting neural sources of NO, possibly via a mechanism related to the pathobiology of asthma. To establish whether FVC maneuvers influence NO concentrations in normal individuals, we measured exhaled NO at baseline values and after FVC maneuvers performed every 15 min for 1 h in subjects without asthma. To investigate the role of deep breaths in reducing exhaled NO, we compared these results with concentrations of exhaled NO after plethysmography. Repeated FVC maneuvers over 60 min produced a decrease in NO concentrations in mixed expired gas (F(E)NO; 24.6 +/- 5.1% decrease for F(E)NO, p < 0. 01 versus baseline). In contrast to the results after spirometry, repeated specific airway conductance (sGaw) maneuvers do not have a significant effect on F(E)NO (p = 0.16). These results, which demonstrate that in nonasthmatic subjects FVC maneuvers-but not panting maneuvers-produce a fall in NO, suggest that the mechanism responsible for the reduction in exhaled NO after FVC maneuvers is related to volume history of the lung rather than the pathobiology of asthma.
Campion, E. W., G. D. Curfman, et al. (2000). "Tracking the peer-review process." N Engl J Med 343(20): 1485-6.
Yandava, C. N., B. P. Kennedy, et al. (1999). "Cytogenetic and radiation hybrid mapping of human arachidonate 5-lipoxygenase-activating protein (ALOX5AP) to chromosome 13q12." Genomics 56(1): 131-3.
Arachidonate 5-lipoxygenase-activating protein (ALOX5AP) is an arachidonic acid binding protein that has been shown to be critical in the biosynthesis of leukotrienes. We mapped the ALOX5AP gene to the chromosome 13q12 region by cytogenetic mapping, yeast artificial chromosome (YAC) pool screening, and radiation hybrid mapping. It was mapped to YAC contig WC13.2 by YAC pool screening with an unambiguous hit to WI-4874, which is at 78 cR on the radiation hybrid map, 3.36 cR, by radiation hybrid mapping, from WI-4874.
Yandava, C. N., A. Pillari, et al. (1999). "Radiation hybrid and cytogenetic mapping of SOCS1 and SOCS2 to chromosomes 16p13 and 12q, respectively." Genomics 61(1): 108-11.
Suppressor of cytokine signaling (SOCS) proteins are involved in the negative regulation of cytokine-induced STAT (signal transducers and activators of transcription) factor signaling. We cloned genomic regions of SOCS1 and SOCS2 genes and mapped these genes to chromosome 16p12-p13.1 and chromosome 12q21.3-q23 regions, respectively, by cytogenetic and radiation hybrid mapping. In addition, we mapped SOCS2 by yeast artificial chromosome (YAC) pool screening to YAC contig WC 12.5 on chromosome 12 with an unambiguous hit to CHLC.ATA19H12 and WI-5940, which is 461.5 cR from the top of the map.
Wechsler, M. and J. M. Drazen (1999). "Churg-Strauss syndrome." Lancet 353(9168): 1970-1.
Wechsler, M. E. and J. M. Drazen (1999). "Zafirlukast and Churg-Strauss syndrome." Chest 116(1): 266-7.
Wechsler, M. E., R. Pauwels, et al. (1999). "Leukotriene modifiers and Churg-Strauss syndrome: adverse effect or response to corticosteroid withdrawal?" Drug Saf 21(4): 241-51.
Zafirlukast, montelukast and pranlukast are all cysteinyl leukotriene receptor antagonists that have recently been approved for the treatment of asthma. Within 6 months of zafirlukast being made available on the market, 8 patients who received the agent for moderate to severe asthma developed eosinophilia, pulmonary infiltrates, cardiomyopathy and other signs of vasculitis; the syndrome that these patients developed was characteristic of the Churg-Strauss syndrome. All of the patients had discontinued systemic corticosteroid use within 3 months of presentation and all developed the syndrome within 4 months of zafirlukast initiation. The syndrome dramatically improved in each patient upon reinitiation of corticosteroid therapy. Since the initial report, there have been multiple similar cases reported to the relevant pharmaceutical companies and to federal drug regulatory agencies in association with zafirlukast as well as with pranlukast, montelukast, and with use of high doses of inhaled corticosteroids, thus leading to an increased incidence rate of the Churg-Strauss syndrome. Many potential mechanisms for the association between these drugs and the Churg-Strauss syndrome have been postulated including: increased syndrome reporting due to bias; potential for allergic drug reaction; and leukotriene imbalance resulting from leukotriene receptor blockade. However, careful analysis of all reported cases suggests that the Churg-Strauss syndrome develops primarily in those patients taking these asthma medications who had an underlying eosinophilic disorder that was being masked by corticosteroid treatment and unmasked by novel asthma medication-mediated corticosteroid withdrawal, similar to the forme fruste of the Churg-Strauss syndrome. It remains unclear what the exact mechanism for this syndrome is and whether this represents an absolute increase in cases of vasculitis, but it appears that none of the asthma medications implicated in leading to the development of Churg-Strauss syndrome was directly causative of the syndrome. These agents remain well tolerated and effective medications for the treatment of asthma, although physicians must be wary for the signs and symptoms of the Churg-Strauss syndrome, particularly in patients with moderate to severe asthma in whom corticosteroids are tapered.
Silverman, E. S. and J. M. Drazen (1999). "The biology of 5-lipoxygenase: function, structure, and regulatory mechanisms." Proc Assoc Am Physicians 111(6): 525-36.
5-Lipoxygenase (5-LO) catalyzes the two-step conversion of arachidonic acid to leukotriene A4 (LTA4). The first step consists of the oxidation of arachidonic acid to the unstable intermediate 5-hydroperoxyeicosatetraenoic acid (5-HPETE), and the second step is the dehydration of 5-HPETE to form LTA4. These events are the first committed reactions leading to the synthesis of all leukotrienes and play a critical role in controlling leukotriene production. 5-LO has evolved many complex structural features and regulatory mechanisms to allow it to fulfill this highly specialized role. The biology of 5-LO is reviewed here with an emphasis on enzymatic function, protein and gene structure, essential cofactors, and the many regulatory mechanisms controlling its expression.
Noviski, N., J. P. Brewer, et al. (1999). "Mast cell activation is not required for induction of airway hyperresponsiveness by ozone in mice." J Appl Physiol 86(1): 202-10.
Exposure to ambient ozone (O3) is associated with increased exacerbations of asthma. We sought to determine whether mast cell degranulation is induced by in vivo exposure to O3 in mice and whether mast cells play an essential role in the development of pulmonary pathophysiological alterations induced by O3. For this we exposed mast cell-deficient WBB6F1-kitW/kitW-v (kitW/kitW-v) mice and the congenic normal WBB6F1 (+/+) mice to air or to 1 or 3 parts/million O3 for 4 h and studied them at different intervals from 4 to 72 h later. We found evidence of O3-induced cutaneous, as well as bronchial, mast cell degranulation. Polymorphonuclear cell influx into the pulmonary parenchyma was observed after exposure to 1 part/milllion O3 only in mice that possessed mast cells. Airway hyperresponsiveness to intravenous methacholine measured in vivo under pentobarbital anesthesia was observed in both kitW/kitW-v and +/+ mice after exposure to O3. Thus, although mast cells are activated in vivo by O3 and participate in O3-induced polymorphonuclear cell infiltration into the pulmonary parenchyma, they do not participate detectably in the development of O3-induced airway hyperresponsiveness in mice.
Nakamura, H., S. T. Weiss, et al. (1999). "Eotaxin and impaired lung function in asthma." Am J Respir Crit Care Med 160(6): 1952-6.
We performed an association study of plasma eotaxin levels, eosinophil counts, total IgE levels, asthma diagnosis, and lung function in an ethnically diverse and geographically dispersed population. We studied 515 asthmatic and 519 normal subjects, none of whom was taking inhaled or oral corticosteroids. Logistic regression analysis demonstrated a direct relationship between asthma diagnosis and eotaxin levels (p < 0.0001). The odds of an asthma diagnosis increased with eotaxin quartile, with the highest quartile having an odds ratio of 5.4 (95% CI 3.2 to 9.2, p < 0.001) compared with the lowest eotaxin quartile. Eotaxin levels were inversely related to lung function (p < 0.001), with the mean percent predicted FEV(1) in the highest eotaxin quartile being 13.5 percentage points (SEM 2.1, p < 0.001) less than that in the lowest quartile. Plasma eotaxin levels were associated with asthma and inversely related to lung function independent of age, race, sex, or smoking status. When combined with eosinophil counts and IgE levels, eotaxin levels contributed to the odds of an asthma diagnosis and of impaired lung function. Our results are the first to associate eotaxin levels with asthma diagnosis and compromised lung function in a large geographically and ethnically diverse population.
MacLean, J. A., A. Sauty, et al. (1999). "Antigen-induced airway hyperresponsiveness, pulmonary eosinophilia, and chemokine expression in B cell-deficient mice." Am J Respir Cell Mol Biol 20(3): 379-87.
Murine models of allergen-induced pulmonary inflammation share many features with human asthma, including the development of antigen-induced pulmonary eosinophilia, airway hyperresponsiveness, antigen-specific cellular and antibody responses, the elaboration of Th2 cytokines (interleukin [IL]-4 and IL-5), and the expression of chemokines with activity for eosinophils. We examined the role of B cells and antigen-specific antibody responses in such a model by studying the histopathologic and physiologic responses of B cell-deficient mice compared with wild-type controls, following systemic immunization and airway challenge with ovalbumin (OVA). Both OVA-challenged wild-type and B cell-deficient mice developed (1) airway hyperresponsiveness, (2) pulmonary inflammation with activated T cells and eosinophils, (3) IL-4 and IL-5 secretion into the airway lumen, and (4) increased expression of the eosinophil active chemokines eotaxin and monocyte chemotactic protein-3. There were no significant differences in either the pathologic or physiologic responses in the B cell-deficient mice compared with wild-type mice. These data indicate that B cells and antigen-specific antibodies are not required for the development of airway hyperresponsiveness, eosinophilic pulmonary inflammation, and chemokine expression in sensitized mice following aerosol challenge with antigen.
Lilly, C. M., P. G. Woodruff, et al. (1999). "Elevated plasma eotaxin levels in patients with acute asthma." J Allergy Clin Immunol 104(4 Pt 1): 786-90.
BACKGROUND: The eosinophil chemotactic and activating effects of eotaxin and the known association of eosinophils with asthma suggest that eotaxin expression is increased during asthma exacerbations. OBJECTIVE: We sought to determine whether plasma eotaxin levels are elevated in patients presenting for emergency treatment of acute asthma and to correlate eotaxin levels with disease activity and responses to treatment. METHODS: A case-control study of plasma eotaxin levels was performed in the 46 patients who presented for emergency asthma treatment and 133 age-, sex-, and ethnicity-matched subjects with stable asthma. RESULTS: Plasma eotaxin levels were significantly higher in 46 patients with acute asthma symptoms and airflow obstruction (520 pg/mL [250, 1100 pg/mL]; geometric mean [-1 SD, +1 SD]) than in 133 subjects with stable asthma (350 pg/mL [190, 620 pg/mL]; P =.0008). Among the patients with emergency asthma flares, those who responded to asthma treatment with an increase in peak expiratory flow rate by an amount equal to at least 20% of their predicted normal value had lower eotaxin levels than those who did not (410 pg/mL [210, 800 pg/mL] and 660 pg/mL [300, 1480 pg/mL], respectively; P =.04). CONCLUSION: These findings imply that eotaxin either is mechanistically involved in acute asthma or serves as a biomarker for activity of the CCR3 receptor ligand system, which is functionally linked to asthma.
In, K. H., E. S. Silverman, et al. (1999). "Mutations in the human 5-lipoxygenase gene." Clin Rev Allergy Immunol 17(1-2): 59-69.
Our data demonstrate the presence of a naturally occurring family of alleles in the core promoter of the 5-LO gene, which is characterized by the deletion or addition of consensus Sp1 (-GGGCGG) and Egr-1 (-GCGGGGGCG-) binding motifs. Each of the variant alleles can bind Sp1 and Egr-1 protein, as indicated by EMSA and supershift analysis with nuclear extracts. In addition, preliminary data from CAT reporter assays indicate that these alleles are less effective than the wild-type allele in initiating 5-LO gene expression. Whether patients harboring the various alleles identified herein have different capacities to transcribe the 5-LO gene and the importance of such potential regulation to the clinical expression of 5-LO have yet to be determined.
Grasemann, H., J. M. Drazen, et al. (1999). "Simple tandem repeat polymorphisms in the neuronal nitric oxide synthase gene in different ethnic populations." Hum Hered 49(3): 139-41.
Allelic frequencies of a CA dinucleotide repeat in exon 29 and an intronic AAT trinucleotide repeat in the neuronal nitric oxide synthase (NOS1) gene were determined by simple sequence length polymorphism (SSLP) in 305 American-Caucasian and 105 African-American healthy subjects. There were highly significant differences in allele frequencies between the two ethnically diverse study populations.
Grasemann, H., C. N. Yandava, et al. (1999). "Neuronal NO synthase (NOS1) is a major candidate gene for asthma." Clin Exp Allergy 29 Suppl 4: 39-41.
Asthma is a common, but heterogeneous disease, characterized by reversible airway obstruction, bronchial hyperresponsiveness (BHR); and is commonly associated with atopy. The messenger molecule nitric oxide (NO), that is formed by neuronal NO synthase (NOS1), is known to have a key role in bronchomotor control in animals. In humans the gene for NOS1 is located on chromosome 12q24, in a region that had been shown in family studies to be linked to the diagnosis of asthma. We identified variants of the NOS1 gene, and assessed whether there was a genetic association between these variants of NOS1 and the diagnosis asthma. A total of 410 Caucasian asthma patients and 228 Caucasian controls were screened for three bi-allelic polymorphisms in the NOS1 gene that had been detected by single-stranded conformational polymorphism (SSCP) analysis and confirmed by sequencing. Allele frequencies of a polymorphism in exon 29 of the NOS1 gene were significantly different between asthmatics and controls (P<0.05). These findings suggest that variants of the NOS1 gene may be one source of genetic risk for asthma.
Drazen, J. M., E. Israel, et al. (1999). "Treatment of asthma with drugs modifying the leukotriene pathway." N Engl J Med 340(3): 197-206.
Drazen, J. M., P. W. Finn, et al. (1999). "Mouse models of airway responsiveness: physiological basis of observed outcomes and analysis of selected examples using these outcome indicators." Annu Rev Physiol 61: 593-625.
The mouse is an ideal species for investigation at the interface of lung biology and lung function. As detailed in this review, there are well-developed methods for the quantitative study of lung function in mice. These methods can be applied to mice in both terminal and nonterminal experiments. Terminal experimental approaches provide more detailed physiological information, but nonterminal measurements provide adequate data for certain experiments. In this review, we provide two examples of how these models can be used to further understanding of the primary pathobiology of airway responsiveness in both the absence and the presence of induced airway inflammation. The first model is a dissection of chromosomal loci linked to the variance in airway responsiveness observed in the absence of any manipulation to induce airway inflammation. The second model explores the role of T-cell costimulatory signals in the induction of airway hyperresponsiveness. As the number of mice with targeted deletions of effector genes or insertion of informative transgenes grows, additional examples are likely to accrue.
Drazen, J. M. and E. S. Silverman (1999). "Genetic determinants of 5-lipoxygenase transcription." Int Arch Allergy Immunol 118(2-4): 275-8.
BACKGROUND: 5 Lipoxygenase (5-LO) is a critical enzyme in the production of the leukotrienes. We have identified a series of mutations in the 5-LO gene that modify gene transcription. These mutations consist of addition of an Sp-1 binding motif (-GGGCGG-) or deletion of one or two Sp-1 binding motifs in the 5-LO core promoter. METHODS: Mutant forms of the 5-LO core promoter were placed in a chloramphenicol acetyl transferase (CAT) reporter construct using either HeLa or SL-2 cells. RESULTS: In HeLa cells all of the mutant forms are less effective in driving CAT reporter activity than the wild-type promoter. In SL-2 cells the construct containing the addition mutation was more effective in driving CAT reporter activity, while the constructs containing the deletion mutations were less effective. CONCLUSIONS: These data indicate that naturally occurring mutations in the 5-LO core promoter modify gene transcription in vitro.
Drazen, J. M., C. N. Yandava, et al. (1999). "Pharmacogenetic association between ALOX5 promoter genotype and the response to anti-asthma treatment." Nat Genet 22(2): 168-70.
Clinically similar asthma patients may develop airway obstruction by different mechanisms. Asthma treatments that specifically interfere with the 5-lipoxygenase (ALOX5) pathway provide a method to identify those patients in whom the products of the ALOX5 pathway (that is, the leukotrienes) contribute to the expression of the asthma phenotype. Failure of an asthma patient to respond to treatment with ALOX5-pathway modifiers indicates that leukotrienes are not critical to the expression of the asthmatic phenotype in that patient. We previously defined a family of DNA sequence variants in the core promoter of the gene ALOX5 (on chromosome 10q11.2) associated with diminished promoter-reporter activity in tissue culture. Because expression of ALOX5 is in part transcriptionally regulated, we reasoned that patients with these sequence variants may have diminished gene transcription, and therefore decreased ALOX5 product production and a diminished clinical response to treatment with a drug targeting this pathway. Such an effect indicates an interaction between gene promoter sequence variants and drug-treatment responses, that is, a pharmacogenetic effect of a promoter sequence on treatment responses.
Drazen, J. M., T. Takebayashi, et al. (1999). "Animal models of asthma and chronic bronchitis." Clin Exp Allergy 29 Suppl 2: 37-47.
Human asthma is characterized by three critical phenotypic traits: intermittent reversible airway obstruction, airway hyperresponsiveness and airway inflammation. In animal models of asthma, airway hyperresponsiveness is an important feature. This trait is characterized by an exaggerated bronchoconstrictor response that would have little physiological consequence in an otherwise unaffected or normal individual. In this article we explore two distinct facets of airway responsiveness. The first is the genetic basis for variations in airway responsiveness that occur in mice in the absence of any specific environmental manipulation. We demonstrate that standard genetic approaches can be successfully applied to the identification of regions of the mouse genome linked to the expression of airway hyperresponsiveness. The second topic addressed in this review is the change in airway responsiveness induced in rats by repeated exposure to sulphur dioxide gas. With daily exposure to high concentrations of sulphur dioxide gas, there is chronic injury and repair of epithelial cells. Over time, rats develop mucous hypersecretion, airway inflammation, increased airway resistance and airway hyperresponsiveness. This model has provided useful information on the mechanisms underlying the pathophysiological events that typify the chronic bronchitis in humans.
Drazen, J. M. (1999). "Asthma therapy with agents preventing leukotriene synthesis or action." Proc Assoc Am Physicians 111(6): 547-59.
Elucidation of the biochemistry of leukotriene production and the pharmacology of its actions has led to the development of a number of therapeutic agents shown to be of value in the treatment of asthma. These agents either prevent the synthesis of the leukotrienes, by preventing the action of the 5-lipoxygenase-activating protein or the catalytic action of the 5-lipoxygenase, or by inhibiting the action of leukotrienes at the CysLT1 receptor. Numerous clinical trials in exercise-induced asthma, allergen-induced asthma, aspirin-induced asthma, and spontaneously occurring asthmatic episodes have indicated that these agents are safe and effective asthma treatments.
De Sanctis, G. T., J. A. MacLean, et al. (1999). "Interleukin-8 receptor modulates IgE production and B-cell expansion and trafficking in allergen-induced pulmonary inflammation." J Clin Invest 103(4): 507-15.
We examined the role of the interleukin-8 (IL-8) receptor in a murine model of allergen-induced pulmonary inflammation using mice with a targeted deletion of the murine IL-8 receptor homologue (IL-8r-/-). Wild-type (Wt) and IL-8r-/- mice were systemically immunized to ovalbumin (OVA) and were exposed with either single or multiple challenge of aerosolized phosphate-buffered saline (OVA/PBS) or OVA (OVA/OVA). Analysis of cells recovered from bronchoalveolar lavage (BAL) revealed a diminished recruitment of neutrophils to the airway lumen after single challenge in IL-8r-/- mice compared with Wt mice, whereas multiply challenged IL-8r-/- mice had increased B cells and fewer neutrophils compared with Wt mice. Both Wt and IL-8r-/- OVA/OVA mice recruited similar numbers of eosinophils to the BAL fluid and exhibited comparable degrees of pulmonary inflammation histologically. Both total and OVA-specific IgE levels were greater in multiply challenged IL-8r-/- OVA/OVA mice than in Wt mice. Both the IL-8r-/- OVA/OVA and OVA/PBS mice were significantly less responsive to methacholine than their respective Wt groups, but both Wt and IL-8r mice showed similar degrees of enhancement after multiple allergen challenge. The data demonstrate that the IL-8r modulates IgE production, airway responsiveness, and the composition of the cells (B cells and neutrophils) recruited to the airway lumen in response to antigen.
De Sanctis, G. T., J. A. MacLean, et al. (1999). "Contribution of nitric oxide synthases 1, 2, and 3 to airway hyperresponsiveness and inflammation in a murine model of asthma." J Exp Med 189(10): 1621-30.
Asthma is a chronic disease characterized by increased airway responsiveness and airway inflammation. The functional role of nitric oxide (NO) and the various nitric oxide synthase (NOS) isoforms in human asthma is controversial. To investigate the role of NO in an established model of allergic asthma, mice with targeted deletions of the three known isoforms of NOS (NOS1, 2, and 3) were studied. Although the inducible (NOS2) isoform was significantly upregulated in the lungs of ovalbumin (OVA)-sensitized and -challenged (OVA/OVA) wild-type (WT) mice and was undetectable in similarly treated NOS2-deficient mice, airway responsiveness was not significantly different between these groups. OVA/OVA endothelial (NOS3)-deficient mice were significantly more responsive to methacholine challenge compared with similarly treated NOS1 and NOS1&3-deficient mice. Airway responsiveness in OVA/OVA neuronal (NOS1)-deficient and neuronal/endothelial (NOS1&3) double-deficient mice was significantly less than that observed in similarly treated NOS2 and WT groups. These findings demonstrate an important function for the nNOS isoform in controlling the inducibility of airway hyperresponsiveness in this model of allergic asthma.
De Sanctis, G. T., J. B. Singer, et al. (1999). "Quantitative trait locus mapping of airway responsiveness to chromosomes 6 and 7 in inbred mice." Am J Physiol 277(6 Pt 1): L1118-23.
Quantitative trait locus (QTL) mapping was used to identify chromosomal regions contributing to airway hyperresponsiveness in mice. Airway responsiveness to methacholine was measured in A/J and C3H/HeJ parental strains as well as in progeny derived from crosses between these strains. QTL mapping of backcross [(A/J x C3H/HeJ) x C3H/HeJ] progeny (n = 137-227 informative mice for markers tested) revealed two significant linkages to loci on chromosomes 6 and 7. The QTL on chromosome 6 confirms the previous report by others of a linkage in this region in the same genetic backgrounds; the second QTL, on chromosome 7, represents a novel locus. In addition, we obtained suggestive evidence for linkage (logarithm of odds ratio = 1.7) on chromosome 17, which lies in the same region previously identified in a cross between A/J and C57BL/6J mice. Airway responsiveness in a cross between A/J and C3H/HeJ mice is under the control of at least two major genetic loci, with evidence for a third locus that has been previously implicated in an A/J and C57BL/6J cross; this indicates that multiple genetic factors control the expression of this phenotype.
Celedon, J. C., F. E. Speizer, et al. (1999). "Bronchodilator responsiveness and serum total IgE levels in families of probands with severe early-onset COPD." Eur Respir J 14(5): 1009-14.
Bronchodilator responsiveness has been associated with a subsequent accelerated decline in forced expiratory volume in one second (FEV1). Therefore, bronchodilator responsiveness and total serum immunoglobulin E(IgE) levels were assessed in 184 adult first-degree relatives of probands with severe early-onset chronic obstructive pulmonary disease (COPD) and a control group. Greater bronchodilator responsiveness was found among current smokers or exsmokers who were first-degree relatives of early-onset COPD probands than in currently or exsmoking controls, expressed as increase in FEV1 as a percentage of baseline (5.8+/-8.1 versus 2.9+/-5.1%, p<0.01), absolute increase in FEV1 from baseline (120+/-130 versus 60+/-110 mL, p<0.05), and increase in FEV1 as a percentage of the predicted value (3.6:4.1 versus 2.2+/-3.9%, p<0.05). However, elevated total serum IgE levels were not found in first-degree relatives of early-onset COPD probands compared with control subjects. The increased bronchodilator responsiveness among currently smoking/exsmoking first-degree relatives of early-onset COPD probands suggests that these individuals may have enhanced susceptibility to the detrimental effects of cigarette smoking.
Burchard, E. G., E. K. Silverman, et al. (1999). "Association between a sequence variant in the IL-4 gene promoter and FEV(1) in asthma." Am J Respir Crit Care Med 160(3): 919-22.
Recent family-based studies have revealed evidence for linkage of human chromosome 5q31 to the diagnosis of asthma, elevated serum IgE levels, and bronchial hyperresponsiveness. Among the candidate genes in this region is the gene encoding for human interleukin-4 (IL-4). We reasoned that this gene could also serve as a candidate gene with respect to asthma severity as indicated by the FEV(1) measured when bronchodilator treatment was withheld. To test this hypothesis, we examined a large population of patients with asthma (ascertained without respect to genetic characteristics), for associations between a genetic variant in the IL-4 promoter region (C-589T) and asthma severity, as indicated by FEV(1). We used amplification by the polymerase chain reaction followed by BsmF1 restriction digestion to assign genotypes at the IL-4 promoter C-589T locus. We compared genotypes at this locus in 772 Caucasian and African American patients with asthma of varying severity, and we used multiple regression analysis to relate genotypic findings to FEV(1). Among white individuals, the homozygous presence of the C-589T IL-4 promoter genotype (TT) was associated with a FEV(1) below 50% of predicted (p = 0.013; OR, 1.44; 95% CI: 1.09 to 1.90). Subjects with the TT genotype had mean FEV(1) (% predicted) values 4.5% lower than those of subjects with the wild-type (CC) genotype at this locus. FEV(1) values of white patients with a CC or CT genotype were broadly distributed, whereas the TT genotype was associated with a narrow distribution of low FEV(1) values. The frequency of the T allele was significantly greater (p = 1 x 10(-)(23)) among African American asthmatics (0.544) than among white asthmatics (0.183). These data provide the first evidence associating FEV(1) in patients with asthma and genetic determinants at any locus. Our data are consistent with the idea that the FEV(1) in asthma is the result of multiple factors; one of these factors is the genotype at the IL-4 C-589T locus. This locus is associated with a small but significant decrement in pulmonary function among white asthmatic subjects.
Wolyniec, W. W., G. T. De Sanctis, et al. (1998). "Reduction of antigen-induced airway hyperreactivity and eosinophilia in ICAM-1-deficient mice." Am J Respir Cell Mol Biol 18(6): 777-85.
A murine model of asthma is described in which we examined the role of intercellular adhesion molecule-1 (ICAM-1) in the pathogenesis of airway reactivity, pulmonary eosinophilia, and inflammation. We sensitized wild-type control [C57BL/6J, (+/+)] and ICAM-1 knockout [C57BL/6J-ICAM-1, (-/-)] mice to ovalbumin (OVA), and challenged them with OVA delivered by aerosol (OVA-OVA) to induce a phenotype consistent with an asthmatic response. Bronchial responsiveness to methacholine and counts of cell numbers and measurements of eosinophil content and cytokine levels in bronchoalveolar lavage fluid (BALF) were significantly attenuated in ICAM-1(-/-) mice as compared with (+/+) mice. We also showed that the absence of ICAM-1 had no significant affects on the production of serum IgE antibody, but did have an effect on ex vivo lymphocyte proliferation. Additionally, immunohistochemistry: (1) revealed increased staining for vascular cell adhesion molecule-1 (VCAM-1) after antigen challenge in the ICAM-1(-/-) mice but not in the ICAM-1(+/+) controls; and (2) confirmed the presence of alternatively spliced forms of ICAM-1 in the lungs of ICAM-1(-/-) mice. Thus, despite the availability of alternate adhesion pathways in ICAM-1(-/-) mice, the absence of ICAM-1 prevented eosinophils from entering the airways. In summary, we found that the ICAM-1 knockout mice exhibited a significantly inhibited response to aerosol antigen challenge for most of the parameters examined, and conclude that ICAM-1 is an important ligand mediating T-cell proliferation in response to antigen, eosinophil migration into the airways, and the development of airway hyperreactivity (AHR) in allergen-sensitized and -challenged mice.
Wechsler, M. E., E. Garpestad, et al. (1998). "Pulmonary infiltrates, eosinophilia, and cardiomyopathy following corticosteroid withdrawal in patients with asthma receiving zafirlukast." Jama 279(6): 455-7.
CONTEXT: Zafirlukast is a potent leukotriene antagonist that recently was approved for the treatment of asthma. As use of this drug increases, adverse events that occur at low frequency or in populations not studied in premarketing clinical trials may become evident. OBJECTIVE: To describe a clinical syndrome associated with zafirlukast therapy. DESIGN: Case series. PATIENTS: Eight adults (7 women and 1 man) with steroid-dependent asthma who received zafirlukast. MAIN OUTCOME MEASURES: Development of a clinical syndrome characterized by pulmonary infiltrates, cardiomyopathy, and eosinophilia following the withdrawal of corticosteroid treatment. RESULTS: The clinical syndrome developed while patients were receiving zafirlukast from 3 days to 4 months and from 3 days to 3 months after corticosteroid withdrawal. All 8 patients developed leukocytosis (range, 14.5-27.6 x 10(9)/L) with eosinophilia (range, 0.19-0.71). Six patients had fever (temperature >38.5 degrees C), 7 had muscle pain, 6 had sinusitis, and 6 had biopsy evidence of eosinophilic tissue infiltration. The clinical syndrome improved with discontinuation of zafirlukast treatment and reinitiation of corticosteroid treatment or addition of cyclophosphamide treatment. COMMENT: Development of pulmonary infiltrates, cardiomyopathy, and eosinophilia may have occurred independent of zafirlukast use or may have resulted from an allergic response to this medication. We suspect that these patients may have had a primary eosinophilic infiltrative disorder that had been clinically recognized as asthma, was quelled by steroid treatment, and was unmasked following corticosteroid withdrawal facilitated by zafirlukast.
Silverman, E. K., H. A. Chapman, et al. (1998). "Genetic epidemiology of severe, early-onset chronic obstructive pulmonary disease. Risk to relatives for airflow obstruction and chronic bronchitis." Am J Respir Crit Care Med 157(6 Pt 1): 1770-8.
Severe alpha-1-antitrypsin deficiency is the only proven genetic risk factor for chronic obstructive pulmonary disease (COPD). We have assembled a cohort of 44 probands with severe, early-onset COPD, who do not have severe alpha-1-antitrypsin deficiency. A surprisingly high prevalence of females (79.6%) was found. Assessment of the risk to relatives of these early-onset COPD probands for airflow obstruction and chronic bronchitis was performed to determine whether significant familial aggregation for COPD, independent of alpha-1-antitrypsin deficiency, could be demonstrated. First- degree relatives of early-onset COPD probands had significantly lower FEV1 and FEV1/FVC values than control subjects (p < 0.01), despite similar pack-years of smoking. Reduced spirometric values in first-degree relatives of early-onset COPD probands were found only in current or ex-cigarette smokers. The mean FEV1 in current or ex-smoking first-degree relatives was 76.1 +/- 20.9% predicted compared to 89.2 +/- 14.4% predicted in current or ex-smoking control subjects (p < 0.01); in lifelong nonsmokers, the mean FEV1 was 93.4% predicted for both control subjects and first-degree relatives of early-onset COPD probands. Generalized estimating equations, adjusting for age and pack-years of smoking, demonstrated increased odds of reduced FEV1 and chronic bronchitis in current or ex-smoking first-degree relatives of early-onset COPD probands. Using a new method to estimate relative risk from relative odds, we estimate that the relative risks for FEV1 below 60%, FEV1 below 80%, and chronic bronchitis are each approximately three in current or ex-smoking first-degree relatives of early-onset COPD probands. The increased risk to relatives of early-onset COPD probands for reduced FEV1 and chronic bronchitis, limited to current or ex-smokers, suggests genetic risk factor(s) for COPD that are expressed in response to cigarette smoking.
Silverman, E. S., J. Du, et al. (1998). "Egr-1 and Sp1 interact functionally with the 5-lipoxygenase promoter and its naturally occurring mutants." Am J Respir Cell Mol Biol 19(2): 316-23.
5-Lipoxygenase (5-LO), an enzyme essential for the formation of leukotrienes, is functionally modulated by a number of mechanisms, including transcriptional controls. The 5-LO promoter has a unique G+C-rich sequence, located between 176 and 147 base pairs upstream of the ATG translation start site, which contains five tandem Sp1 (a zinc-finger transcription factor) consensus binding sites overlapping five tandem early growth response protein 1 (Egr-1), a zinc-finger transcription factor, consensus binding sites. A family of naturally occurring mutations has been identified that consists of additions or deletions of these binding sites. The role of these overlapping Sp1/Egr-1 sites in the regulation of 5-LO transcription and the effects of these mutations on transcriptional regulatory mechanisms are unknown. We now show that Sp1 and Egr-1 bind specifically to the G+C-rich promoter sequence using in vitro deoxyribonuclease I footprinting. Both Sp1 and Egr-1 activate 5-LO promoter-reporter constructs in a minimally active drosophila SL2 cotransfection system, and the G+C-rich sequence is involved in this process. Moreover, studies comparing mutant promoter function indicate that both Sp1 and Egr-1 trans-activation are proportional to the number of Sp1/Egr-1 consensus binding sites within the G+C-rich sequence. It is possible that basal and inducible 5-LO gene transcriptions are mediated by an interplay of Sp1, Egr-1, and other transcription factors within the G+C-rich promoter region, and the naturally occurring mutations alter transcription by modifying their trans-activation potential.
Silverman, E. S., J. Du, et al. (1998). "cAMP-response-element-binding-protein-binding protein (CBP) and p300 are transcriptional co-activators of early growth response factor-1 (Egr-1)." Biochem J 336 ( Pt 1): 183-9.
Egr-1 (early-growth response factor-1) is a sequence-specific transcription factor that plays a regulatory role in the expression of many genes important for cell growth, development and the pathogenesis of disease. The transcriptional co-activators CBP (cAMP-response-element-binding-protein-binding protein) and p300 interact with sequence-specific transcription factors as well as components of the basal transcription machinery to facilitate RNA polymerase II recruitment and transcriptional initiation. Here we demonstrate a unique way in which Egr-1 physically and functionally interacts with CBP/p300 to modulate gene transcription. CBP/p300 potentiated Egr-1 mediated expression of 5-lipoxygenase (5-LO) promoter-reporter constructs, and the degree of trans-activation was proportional to the number of Egr-1 consensus binding sites present in wild-type and naturally occurring mutants of the 5-LO promoter. The N- and C-terminal domains of CBP interact with the transcriptional activation domain of Egr-1, as demonstrated by a mammalian two-hybrid assay. Direct protein-protein interactions between CBP/p300 and Egr-1 were demonstrated by glutathione S-transferase fusion-protein binding and co-immunoprecipitation/Western-blot studies. These data suggest that CBP and p300 act as transcriptional co-activators for Egr-1-mediated gene expression and that variations between individuals in such co-activation could serve as a genetic basis for variability in gene expression.
Silverman, E., K. H. In, et al. (1998). "Pharmacogenetics of the 5-lipoxygenase pathway in asthma." Clin Exp Allergy 28 Suppl 5: 164-70; discussion 171-3.
It is now well appreciated that asthma is a chronic inflammatory disease of the airways; among the inflammatory cells that have been implicated in the asthmatic lesion are eosinophils and mast cells. Although these cells have the capacity to produce a number of distinct chemical mediators, the cysteinyl leukotrienes have recently been identified as important mediators of the asthmatic response. The leukotrienes are derived from arachidonic acid released from membrane phospholipids by the action of phospholipases. The archidonic acid so released in the presence of the 5-lipoxygenase (5-LO) activating protein becomes a substrate for the enzyme 5-LO. This enzyme catalyses the stereo-specific addition of molecular oxygen to arachidonic acid to form the product known as leukotriene A4. Leukotriene A4 subsequently becomes a substrate for one of two enzymes, leukotriene A4 epoxide hydrolase or LTC4 synthase. The former catalyses the formation of LTB4 while the later catalyses the formation of the cysteinyl leukotrienes. Thus the enzyme 5-LO is critically posed to serve as a regulator of leukotriene synthesis. 5-LO action is known to be regulated at a number of levels; the mechanisms include regulation of action of the mature protein and regulation of 5-LO gene transcription and translation; there is good reason to believe that all forms of 5-LO regulation are highly interdependent. In this regard we describe the presence and functional consequences of a series of naturally occurring mutations in 5-LO core promoter. These mutations modify gene transcription in vitro, and may have functional consequences in vivo.
Ruddy, M. K., J. M. Drazen, et al. (1998). "Modulation of aquaporin 4 and the amiloride-inhibitable sodium channel in perinatal rat lung epithelial cells." Am J Physiol 274(6 Pt 1): L1066-72.
During the perinatal period, a dramatic reversal of lung transepithelial ion and water transport occurs that involves the amiloride-inhibitable Na+ channel (ENaC). Aquaporin (AQP) water channel proteins facilitate cell membrane water transport. We now report that AQP-4, localized to basolateral membranes of airway epithelial cells, increases its mRNA expression in developing lung eightfold during the 2 days before birth to reach a peak on the first postnatal day in the lungs but not in brains or kidneys of neonatal rats. AQP-4 and the alpha-, beta-, and gamma-subunits of ENaC are both expressed by cultured rat fetal distal lung epithelial (FDLE) cells. AQP-4 and ENaC expression increase in FDLE cells cultured on uncoated permeant filters compared with matched control cells cultured on filters containing extracellular matrix derived from fetal lung epithelial cells. Similarly, AQP-4 expression increases in FDLE cells exposed to 21% O2 compared with cells exposed to 3% O2. These data demonstrate that AQP-4 expression is highest on the first day after birth in neonatal rat lungs. Exposure to ambient 21% O2 may contribute to increases in AQP-4 and ENaC expression to facilitate water transport across neonatal airway epithelia in the immediate postnatal period.
Mehta, S., J. Boudreau, et al. (1998). "Endogenous pulmonary nitric oxide in the regulation of airway microvascular leak." Am J Physiol 275(5 Pt 1): L961-8.
Endogenous nitric oxide (NO) is an important modulator of airway function, but its role in the regulation of airway microvascular leak (AMVL) remains unclear. Thus we assessed the effects of NO synthase (NOS) inhibition on expired NO (ENO) levels and on AMVL measured by the Evans blue dye technique in guinea pigs. In control unsensitized animals, systemic NG-nitro-L-arginine methyl ester (L-NAME) reduced ENO by 70 +/- 8% (P < 0.01) and reduced AMVL by 92 +/- 1 and 44 +/- 17% (P < 0.05 for both) in the extrapulmonary and intrapulmonary airways, respectively. In animals sensitized and challenged with intratracheal antigen, markedly increased levels of AMVL and ENO were similarly attenuated by L-NAME. In contrast, aminoguanidine, a relatively selective type II NOS inhibitor, reduced ENO in both antigen-sensitized and control unsensitized animals by 39 +/- 3% (P < 0.01) but had no effect on AMVL. These data indicate that endogenous pulmonary NO contributes to both basal and antigen-stimulated levels of AMVL in guinea pigs and that this NO-dependent activity does not appear to be derived from type II NOS.
Haley, K. J. and J. M. Drazen (1998). "Inflammation and airway function in asthma: what you see is not necessarily what you get." Am J Respir Crit Care Med 157(1): 1-3.
Haley, K. J., M. E. Sunday, et al. (1998). "Inflammatory cell distribution within and along asthmatic airways." Am J Respir Crit Care Med 158(2): 565-72.
Asthmatic airways are infiltrated with inflammatory cells that release mediators and cytokines into the microenvironment. In this study, we evaluated the distribution of CD45-positive leukocytes and eosinophils in lung tissue from five patients who died with severe asthma compared with five patients with cystic fibrosis. For morphometric analysis, the airway wall was partitioned into an "inner" area (between basement membrane and smooth muscle) and an "outer" area (between smooth muscle and alveolar attachments). Large airways (with a perimeter greater than 3.0 mm) from patients with asthma or cystic fibrosis had a greater density of CD45-positive cells (p < 0.05) and eosinophils (p < 0.001) in the inner airway region compared with the same airway region in small airways. Furthermore, in small airways, asthmatic lungs showed a greater density of CD45-positive cells (p < 0.01) and eosinophils (p < 0.01) in the outer compared with the inner airway wall region. These observations indicate that there are regional variations in inflammatory cell distribution within the airway wall in patients with asthma that are not observed in airways from patients with cystic fibrosis. We speculate that this inflammatory cell density in peripheral airways in severe asthma may relate to the peripheral airway obstruction characteristic of this condition.
Drazen, J. M. (1998). "New directions in asthma drug therapy." Hosp Pract (Off Ed) 33(2): 25-6, 31-3, 36-8.
A new generation of biologically informative treatments has altered our understanding of the disease--transforming what used to be viewed as a single entity into a family of airway disorders driven by different proinflammatory mediators. Although inhaled corticosteroids have been the treatment of choice for most patients, research is increasingly aimed at developing inhibitors targeted to specific effector systems.
Drazen, J. M. (1998). "Leukotrienes as mediators of airway obstruction." Am J Respir Crit Care Med 158(5 Pt 3): S193-200.
The cysteinyl leukotrienes are potent mediators of airway narrowing derived from the lipoxygenation of arachidonic acid and the adduction of glutathione to this eicosanoid backbone. In lower animals and humans, the cysteinyl leukotrienes are among the most potent airway contractile substances ever identified. Furthermore, these moieties can be recovered from the urine during induced or spontaneous asthma attacks. Most important, inhibition of the synthesis of the leukotrienes or prevention of their action at the CysLT1 receptor is associated with an improvement in the airway dysfunction that occurs in both induced and spontaneous asthma. These data indicate that the cysteinyl leukotrienes have a clinically significant role in the airway obstruction that characterizes asthma.
Drazen, J. M. and E. Israel (1998). "Should antileukotriene therapies be used instead of inhaled corticosteroids in asthma? Yes." Am J Respir Crit Care Med 158(6): 1697-8.
Deykin, A., O. Halpern, et al. (1998). "Expired nitric oxide after bronchoprovocation and repeated spirometry in patients with asthma." Am J Respir Crit Care Med 157(3 Pt 1): 769-75.
Compared with normal individuals, subjects with asthma have elevated levels of expired nitric oxide (NO). These levels are hypothesized to reflect the degree of airway inflammation. Expired NO levels rise during the late phase of allergen challenge and decrease in asthmatics after steroid treatment. Isocapnic cold air hyperventilation (ISH) is believed to cause airway narrowing through noninflammatory mechanisms. We measured mixed expired NO in 10 individuals with atopic asthma who underwent both ISH challenge and allergen challenge, and compared these measurements with the change in expired NO that occurred after serial spirometry alone. We found that ambient NO levels affected mixed expired NO. Controlling for inspired NO, we found that repeated spirometry alone produced a significant fall in mixed expired NO (p < 0.01) that was maximal after 30 min (36.6 +/- 8.5% fall). After allergen and ISH challenges, expired NO was elevated relative to levels after repeated spirometry (p < 0.01 and p = 0.065, respectively). In addition, we found that prechallenge expired NO levels were significantly correlated with the magnitude of the late fall in FEV1 following allergen challenge (r = 0.80, p < 0.01). These data demonstrate that repeated spirometry results in reduced mixed expired NO and suggest that both ISH and allergen-induced bronchoconstriction share pathobiologic mechanisms that produce increases in mixed expired NO.
Wiggs, B. R., C. A. Hrousis, et al. (1997). "On the mechanism of mucosal folding in normal and asthmatic airways." J Appl Physiol 83(6): 1814-21.
Previous studies have demonstrated that the airway wall in asthma and chronic obstructive pulmonary disease is markedly thickened. It has also been observed that when the smooth muscle constricts the mucosa buckles, forming folds that penetrate into the airway lumen. This folding pattern may influence the amount of luminal obstruction associated with smooth muscle activation. A finite-element analysis of a two-layer composite model for an airway is used to investigate the factors that determine the mucosal folding pattern and how it is altered as a result of changes in the thickness or stiffness of the different layers that comprise the airway wall. Results demonstrate that the most critical physical characteristic is the thickness of the thin inner layer of the model. Thickening of this inner layer likely is represented by the enhanced subepithelial collagen deposition seen in asthma. Other findings show a high shear stress at or near the epithelial layer, which may explain the pronounced epithelial sloughing that occurs in asthma, and steep gradients in pressure that could cause significant shifts of liquid between wall compartments or between the wall and luminal or vascular spaces.
Sobh, J. F., C. M. Lilly, et al. (1997). "Respiratory transfer impedance between 8 and 384 Hz in guinea pigs before and after bronchial challenge." J Appl Physiol 82(1): 172-81.
We report a forced oscillatory technique for noninvasively measuring respiratory transfer impedance (Ztr) between 8 and 384 Hz in guinea pigs. This technique uses a device consisting of two chambers: one surrounding the animal's head that is used as a plethysmograph to measured flow through the airway opening and the other that surrounds the animal's body and is used to apply pressure oscillations to the body surface. Ztr was measured in spontaneously breathing awake guinea pigs and while the animals were anesthetized in normal and methacholine-challenged conditions. An eight-element model consisting of an airway compartment separated from a tissue compartment by a shunt gas compression compartment was fit to the data. Anesthesia increased central and peripheral airway resistance and bronchial airway wall compliance by 13, 31, and 44%, respectively, whereas it decreased tissue compliance by 37%. Compared with the unanesthetized condition, the methacholine challenge (20 micrograms/kg) resulted in an increase in central and peripheral airway resistance (69 and 319%, respectively) and a decrease in bronchial airway wall and tissue compliance (37 and 79%, respectively). This technique is capable of measuring Ztr in anesthetized and awake guinea pigs. Analysis of these data with this eight-element model provides reasonable estimates of airway and tissue parameters.
Serhan, C. N. and J. M. Drazen (1997). "Antiinflammatory potential of lipoxygenase-derived eicosanoids: a molecular switch at 5 and 15 positions?" J Clin Invest 99(6): 1147-8.
O'Byrne, P. M., E. Israel, et al. (1997). "Antileukotrienes in the treatment of asthma." Ann Intern Med 127(6): 472-80.
PURPOSE: To review the activity in clinical models, the efficacy, and the safety of antileukotrienes as a new class of antiasthma treatment. DATA SOURCES: English-language trials identified from the archival literature, including the MEDLINE database, through 1996; bibliographic references; and textbooks. STUDY SELECTION: Reports from placebo-controlled, double-blind, randomized trials were selected. DATA EXTRACTION: Study designs and results were extracted from the clinical trial reports. Statistical evaluation of combined results was not attempted. DATA SYNTHESIS: The various classes of antileukotrienes have shown activity in clinical models of asthma, including exercise-induced, cold air hyperventilation-induced, allergen-induced, and aspirin-induced bronchoconstriction. In addition, the antileukotrienes partially reverse spontaneous bronchoconstriction in asthmatic persons, an effect additive to that of inhaled beta 2-agonists. Clinical trials of the antileukotrienes have shown clinical benefit, as measured by reductions in asthma symptom scores, improvements in air flow obstruction, and reductions in the rescue use of inhaled beta 2-agonists. Some, but not all, of the antileukotrienes have been shown to cause liver microsomal activation with increases in hepatic aminotransferase levels. CONCLUSIONS: Antileukotrienes are an important new therapy for asthma. Inhibition of leukotriene synthesis or action has a beneficial effect in the treatment of both induced and spontaneous asthma. These results show that leukotrienes are important mediators of the asthmatic response. In addition, encouraging results have been obtained from clinical trials of antileukotrienes; however, these results do not yet provide guidelines for the optimal clinical use of antileukotrienes in asthma treatment. Such recommendations await the results of further studies.
Mehta, S., C. M. Lilly, et al. (1997). "Acute and chronic effects of allergic airway inflammation on pulmonary nitric oxide production." Am J Physiol 272(1 Pt 1): L124-31.
Nitric oxide (NO) is thought to be an important modulator of airway function in normal and inflamed airways. We investigated the acute and chronic effects of induced allergic airway inflammation on NO levels in mixed expired gas and NO synthase (NOS) expression in guinea pigs and the relationship between airway responses and NO production. Airway inflammation was induced by repeated aerosolized antigen exposure, and its presence was confirmed by bronchoalveolar lavage. Acute antigen exposure in sensitized animals produced a fivefold increase in respiratory resistance over baseline that was associated with a cotemporal increase in expired NO (17 +/- 1 to 56 +/- 8 parts per billion, P < 0.01). A continuous subcutaneous infusion of nitro-L-arginine methyl ester (L-NAME), a competitive inhibitor of NOS, markedly decreased expired NO (P < 0.01) and resulted in a significantly greater rise in resistance following antigen challenge (660 +/- 60 vs. 497 +/- 42% of baseline in non-L-NAME-treated animals, P < 0.05). These data support the hypothesis that endogenous pulmonary NO production, as reflected by expired NO, has an important homeostatic role in acute allergic bronchoconstriction.
Mehta, S., J. M. Drazen, et al. (1997). "Endogenous nitric oxide and allergic bronchial hyperresponsiveness in guinea pigs." Am J Physiol 273(3 Pt 1): L656-62.
To address the role of endogenous pulmonary nitric oxide (NO) in the modulation of airway tone, we investigated changes in expired NO levels, measured by chemiluminescence, and the effect of inhibition of NO synthase on inflammation-associated bronchial hyperresponsiveness in guinea pigs. Mixed expired gas NO levels were similar at baseline in antigen-exposed and unexposed animals and increased transiently to a similar degree during histamine-induced bronchoconstriction in both groups of animals [155 +/- 12% (15 +/- 1 to 23 +/- 4 ppb, P < 0.01) and 162 +/- 19% (16 +/- 2 to 25 +/- 3 ppb, P < 0.01) of baseline, respectively, after administration of 30 nmol/kg histamine]. Although inhibition of NO synthase with intravenous NG-nitro-L-arginine methyl ester (L-NAME, 10 mg/kg) enhanced bronchial responsiveness to histamine by 30 +/- 8% in unexposed animals (P < 0.05), L-NAME did not enhance histamine responsiveness in antigen-exposed animals exhibiting bronchial hyperresponsiveness 24 h after antigen exposure. Thus bronchial hyperresponsiveness induced by repeated pulmonary antigen exposure may be associated with a transient defect in NO-related homeostatic bronchodilator activity.
Lilly, C. M., H. Nakamura, et al. (1997). "Expression of eotaxin by human lung epithelial cells: induction by cytokines and inhibition by glucocorticoids." J Clin Invest 99(7): 1767-73.
Eotaxin is a potent and specific eosinophil chemoattractant that is mobilized in the respiratory epithelium after allergic stimulation. Pulmonary levels of eotaxin mRNA are known to increase after allergen exposure in sensitized animals. In this study we demonstrate that TNF alpha and IL-1beta induce the accumulation of eotaxin mRNA in the pulmonary epithelial cell lines A549 and BEAS 2B in a dose-dependent manner. Cytokine-induced A549 cell mRNA accumulation was maximal at 4 h and was significantly enhanced when the cells were costimulated with IFNgamma. TNFalpha- and IL-1beta-induced increases in eotaxin mRNA were diminished in a dose-dependent manner by the glucocorticoid dexamethasone and were augmented by the protein synthesis inhibitor cycloheximide. Cytokine-induced increases in eotaxin mRNA expression correlated with increased eotaxin protein production and secretion, and dexamethasone inhibition of cytokine-induced eotaxin mRNA augmentation was associated with diminished eotaxin protein secretion. These findings, together with the known kinetics of TNF alpha and IL-1beta mobilization in asthmatic airways and the potent eosinophil chemotactic effects of eotaxin, define a mechanism linking inflammatory cytokine mobilization to eosinophil recruitment that may be relevant to the pathogenesis of asthma.
Levy, B. D., J. M. Drazen, et al. (1997). "Agonist-induced lipoxin A4 generation in vitro and in aspirin-sensitive asthmatics: detection by a novel lipoxin A4-ELISA." Adv Exp Med Biol 400B: 611-5.
In, K. H., K. Asano, et al. (1997). "Naturally occurring mutations in the human 5-lipoxygenase gene promoter that modify transcription factor binding and reporter gene transcription." J Clin Invest 99(5): 1130-7.
Five lipoxygenase (5-LO) is the first committed enzyme in the metabolic pathway leading to the synthesis of the leukotrienes. We examined genomic DNA isolated from 25 normal subjects and 31 patients with asthma (6 of whom had aspirin-sensitive asthma) for mutations in the known transcription factor binding regions and the protein encoding region of the 5-LO gene. A family of mutations in the G + C-rich transcription factor binding region was identified consisting of the deletion of one, deletion of two, or addition of one zinc finger (Sp1/Egr-1) binding sites in the region 176 to 147 bp upstream from the ATG translation start site where there are normally 5 Sp1 binding motifs in tandem. Reporter gene activity directed by any of the mutant forms of the transcription factor binding region was significantly (P < 0.05) less effective than the activity driven by the wild type transcription factor binding region. Electrophoretic mobility shift assays (EMSAs) demonstrated the capacity of wild type and mutant transcription factor binding regions to bind nuclear extracts from human umbilical vein endothelial cells (HUVECs). These data are consistent with a family of mutations in the 5-LO gene that can modify reporter gene transcription possibly through differences in Sp1 and Egr-1 transactivation.
Haley, K. J., J. M. Drazen, et al. (1997). "Comparison of the ontogeny of protein gene product 9.5, chromogranin A and proliferating cell nuclear antigen in developing human lung." Microsc Res Tech 37(1): 62-8.
Pulmonary neuroendocrine cell products, especially bombesin-like peptides, are important modulators of fetal lung growth, morphogenesis and maturation. In the present study, we describe the ontogeny of protein gene product 9.5 (PGP 9.5) in 28 midtrimester human fetal lungs, in comparison to chromogranin A (CGA), a marker of differentiated neuroendocrine cells, and proliferating cell nuclear antigen (PCNA), which is expressed by actively dividing cells. PGP 9.5 immunostaining colocalized with CGA in many cells, although the peak abundance of PGP 9.5 preceded that of CGA by 4 to 6 weeks. In addition, a novel staining pattern was noted for PGP 9.5: diffuse cytoplasmic staining of undifferentiated epithelial cells, which was demonstrated by all of the airways before 15 weeks gestation. After gestational week 15, only the smallest airways demonstrated this pattern. PCNA immunostaining demonstrated age-dependent regional variation. All samples had approximately 25% epithelial cells immunopositive for PCNA. Between 11 and 14 weeks gestation over 50% of the mesenchymal cells were PCNA positive. This mesenchymal staining decreased after 14 weeks, and was rare by week 19. There was no definite correlation between the immunostaining for PGP 9.5 and that for PCNA, although PGP 9.5 positive cells were usually PCNA negative. These observations suggest that other growth factors produced by non-neuroendocrine epithelial cells also participate in lung development.
Grasemann, H., J. M. Drazen, et al. (1997). "Protein sequence of the human neuronal nitric oxide synthase (Type I NOS): an error in the sequence database." Nitric Oxide 1(6): 441.
Fish, J. E., S. P. Peters, et al. (1997). "An evaluation of colchicine as an alternative to inhaled corticosteriods in moderate asthma. National Heart, Lung, and Blood Institute's Asthma Clinical Research Network." Am J Respir Crit Care Med 156(4 Pt 1): 1165-71.
Colchicine demonstrates an array of anti-inflammatory properties of potential relevance to asthma. However, the efficacy of colchicine as an alternative to inhaled corticosteroid therapy for asthma is unknown. Five centers participated in a controlled trial testing the hypothesis that in patients with moderate asthma needing inhaled corticosteroids for control, colchicine provides therapeutic benefit as measured by maintenance of control when inhaled steroids are discontinued. Subjects were stabilized on triamcinolane acetonide (800 microg daily) and then enrolled in a 2-wk run-in during which all subjects took both colchicine (0.6 mg/twice a day) and triamcinolone. At the end of the run-in, all subjects discontinued triamcinolone and were randomized to continued colchicine (n = 35) or placebo (n = 36) for a 6-wk double-blind treatment period. The treatment groups were similar in terms of disease severity. After corticosteroid withdrawal, 60% of colchicine-treated and 56% of placebo-treated subjects were considered treatment failures as defined by preset criteria. No significant difference in survival curves was found between treatment groups (log rank = 0.38). Other measures, including changes in FEV1, peak expiratory flow, symptoms, rescue albuterol use, and quality of life scores, also did not differ between groups. Of note, subjects failing treatment had significantly greater methacholine responsiveness at baseline than did survivors (PC20, 0.81+/-1.38 versus 2.11+/-2.74 mg/ml; p = 0.01). An analysis of treatment failures suggested that the criteria selected for failure reflected a clinically meaningful but safe level of deterioration. We conclude that colchicine is no better than placebo as an alternative to inhaled corticosteroids in patients with moderate asthma. Additionally, we conclude that the use of treatment failure as the primary outcome variable in an asthma clinical trial where treatment is withdrawn is feasible and safe under carefully monitored conditions.
Drazen, J. M. (1997). "Pharmacology of leukotriene receptor antagonists and 5-lipoxygenase inhibitors in the management of asthma." Pharmacotherapy 17(1 Pt 2): 22S-30S.
The leukotrienes (LTs), a family of inflammatory mediators arising from the metabolism of arachidonic acid via the 5-lipoxygenase pathway, are prominently implicated in the pathobiology of asthma. Two classes of LTs, the cysteinyl LTs (LTC4, LTD4, and LTE4) and the dihydroxy-LT (LTB4) have been identified, with each class acting via distinct receptors. Inhibition of LT-mediated inflammation can be achieved by either interruption of 5-lipoxygenase action, thereby preventing formation of the LTs, or inhibition at specific LT receptor sites in the airway. Both the 5-lipoxygenase inhibitors and the cysLT receptor antagonists have thus far demonstrated the capacity to improve pulmonary function and reduce symptoms in clinical models of asthma, such as exercise-, aspirin-, or antigen-induced bronchoconstriction, and to improve pulmonary function in patients with mild-to-moderate, chronic stable asthma. The LTs are therefore critical effector molecules in some patients with asthma and important targets in the pharmacologic management of this disease.
Drazen, J. M. and E. K. Silverman (1997). "Genetics of asthma: conference summary." Am J Respir Crit Care Med 156(4 Pt 2): S69-71.
Drazen, J. M. and D. R. Beier (1997). "The genetics of air pollution." Nat Genet 17(4): 365-6.
De Sanctis, G. T. and J. M. Drazen (1997). "Genetics of airway responsiveness in the inbred mouse." Res Immunol 148(1): 73-9; discussion 79-83.
De Sanctis, G. T., A. Itoh, et al. (1997). "T-lymphocytes regulate genetically determined airway hyperresponsiveness in mice." Nat Med 3(4): 460-2.
Airway hyperresponsiveness (AHR) is a hallmark of asthma and a heritable polygenic trait in the mouse. In the mouse, candidate gene products of hematopoietic origin implicated in asthma mapped to the regions of the previously defined quantitative trait loci. Since hematopoietic cells have been implicated in the pathogenesis of asthma, we evaluated the role of hematopoietic cells in general and T cells specifically in the genetic modulation of native airway responsiveness in mice. Here, with the use of bone marrow transplantation, anti-T-cell monoclonal antibody treatment and T-cell transfer, we demonstrate that intrinsic non-atopic AHR is mediated by T lymphocytes. Our data support the novel concept that, in the absence of identified environmental influences, T cells enhance genetically determined airway responsiveness.
De Sanctis, G. T., W. W. Wolyniec, et al. (1997). "Reduction of allergic airway responses in P-selectin-deficient mice." J Appl Physiol 83(3): 681-7.
P-selectin is an adhesion receptor that has been shown to be important in the recruitment of eosinophils and lymphocytes in a variety of inflammatory conditions. Because cellular recruitment is thought to be a critical event in allergen-induced changes in airway responsiveness, we reasoned that P-selectin-deficient mice would exhibit reduced airway responsiveness and cellular trafficking noted in wild-type (+/+) mice. Both (+/+) and P-selectin-deficient (-/-) mice sensitized and challenged with ovalbumin (OVA/OVA) exhibited the same capacity to produce increased titers of total and OVA-specific immunoglobulin E. Airway responsiveness to methacholine was significantly greater in the (+/+) (OVA/OVA) animals than it was in the respective (-/-) (OVA/OVA) group or control groups (P = 0.0016). Bronchoalveolar lavage fluid from (-/-) (OVA/OVA) mice contained significantly fewer eosinophils and lymphocytes compared with the (+/+) (OVA/OVA) mice (P < 0.05). These results suggest that the predominant role of P-selectin in OVA-induced airway hyperresponsiveness is to promote the airway inflammatory response to allergen inhalation.
De Sanctis, G. T. and J. M. Drazen (1997). "Genetics of native airway responsiveness in mice." Am J Respir Crit Care Med 156(4 Pt 2): S82-8.
The inbred mouse represents a powerful tool for dissecting both simple and complex traits. Genetic studies in the mouse should identify disease genes acting in the same biochemical pathway as in the human. Problems associated with genetic heterogeneity, inability to control environmental conditions, lack of an abundant supply of genetic markers, and ethical considerations regarding human genetic crosses are but some of the reasons to study airway responsiveness in the mouse. At present, only a handful of studies have shed light on the genetics of airway responsiveness; even fewer have sought to identify genetic loci that regulate this trait. It is clear that both genetic and environmental factors influence the asthma phenotype and that genetic background is an important consideration when interpreting segregation analysis data. The controversy over the specific mode of inheritance and number and location of quantitative trait loci (QTL) illustrates the need for additional studies. However, given that numerous candidate loci implicated in the pathogenesis of asthma map near QTLs identified in two recent studies, and given the considerable homology between the human and mouse genome, a targeted search for susceptibility genes is warranted in the human. Ideally, these regions will demonstrate linkage in humans. Thus, further work remains to be done to create detailed maps of the regions of linkage in the mouse, and to ultimately identify gene(s) that modify airway responsiveness. mice.
De Sanctis, G. T., S. Mehta, et al. (1997). "Contribution of type I NOS to expired gas NO and bronchial responsiveness in mice." Am J Physiol 273(4 Pt 1): L883-8.
Nitric oxide (NO) can be measured in the expired gas of humans and animals, but the source of expired NO (F(E)NO) and the functional contribution of the various known isoforms of NO synthase (NOS) to the NO measured in the expired air is not known. F(E)NO was measured in the expired air of mice during mechanical ventilation via a tracheal cannula. F(E)NO was significantly higher in wild-type B6SV129J +/+ mice than in mice with a targeted deletion of type I (neural) NOS (nNOS, -/-) (6.3 +/- 0.9 vs. 3.9 +/- 0.4 parts/billion, P = 0.0345, for +/+ and -/- mice, respectively), indicating that approximately 40% of the NO in expired air in B6SV129 mice is derived from nNOS. Airway responsiveness to methacholine (MCh), assessed by the log of the effective dose of MCh for a doubling of pulmonary resistance from baseline (ED(200)R(L)), was significantly lower in the -/- nNOS mice than in the wild-type mice (logED(200)R(L), 2.24 +/- 0.07 vs. 2.51 +/- 0.06 microg/kg, respectively; P = 0.003). These findings indicate that nNOS significantly contributes to baseline F(E)NO and promotes airway hyperresponsiveness in the mouse.
Asano, K., H. Nakamura, et al. (1997). "Interferon gamma induces prostaglandin G/H synthase-2 through an autocrine loop via the epidermal growth factor receptor in human bronchial epithelial cells." J Clin Invest 99(5): 1057-63.
The induction of prostaglandin G/H synthase (PGHS; prostaglandin endoperoxide synthase, cyclooxygenase) by proinflammatory cytokines accounts, at least in part, for the altered eicosanoid biosynthesis in inflammatory diseases. In secondary cultures of normal human bronchial epithelial cells (NHBECs), interferon-gamma (IFN-gamma, 10 ng/ml for 24 h) increased the amount of prostaglandin E2 (PGE2) released in response to stimulation with exogenous arachidonic acid (5 microM). The enhanced production of PGE2 reflected the upregulation of PGHS-2 as indicated by enhanced expression of PGHS-2 RNA and increased recovery of PGHS-2 protein in NHBECs. IFN-gamma did not alter the production of PGE2 in A549 cells (a human lung adenocarcinoma cell line) or 6-keto-PGF1alpha in human umbilical vein endothelial cells (HUVECs), although prostaglandin release and/or the expression of PGHS-2 RNA in these cell lines was upregulated by other proinflammatory cytokines. Induction of PGHS-2 RNA in IFN-gamma-treated NHBECs, which peaked at 24 h, suggested the presence of an intermediary substance regulating the expression of PGHS-2. When the binding between the epidermal growth factor (EGF) receptor and its ligands was disrupted by a neutralizing antibody (LA-1), IFN-gamma failed to upregulate the release of PGE2 and the expression of PGHS-2 RNA in NHBECs. Furthermore, IFN-gamma induced the expression of RNAs for a number of ligands at the EGF receptor TGF-alpha; heparin-binding EGF-like growth factor (HB-EGF); and amphiregulin in NHBECs, and when administered exogenously, these ligands increased PGE2 release from NHBECs. Heparin at the concentration that neutralized the function of amphiregulin, or antibodies against TGFalpha or HB-EGF also reduced the release of PGE2 from IFN-gamma-stimulated NHBECs. These data are consistent with the presence of an autocrine growth factor/EGF receptor loop regulating PGHS-2 expression and PGE2 synthesis in bronchial epithelial cells.
Yager, D., M. A. Martins, et al. (1996). "Acute histamine-induced flux of airway liquid: role of neuropeptides." J Appl Physiol 80(4): 1285-95.
The role of capsaicin-sensitive neuropeptides in the accumulation of airway wall liquid observed 30 s after histamine infusion was investigated in guinea pigs. Two groups were studied: normal animals and animals in which endogenous neuropeptides had been depleted by capsaicin pretreatment. A rapid intravenous infusion of saline or histamine (11 micrograms/kg resulted in marked but similar changes in pulmonary mechanics in normal and capsaicin-pretreated animals. To assess liquid accumulation in airway wall compartments, the lungs were frozen 30 s after histamine infusion; airways from these lungs, 0.15-2.44 mm in internal perimeter, were imaged by low-temperature scanning electron microscopy. There was no difference in average airway surface liquid thickness (hASL) in normal or capsaicin-pretreated airways in response to saline. In capsaicin-pretreated animals, histamine infusion was associated with a significantly decreased hASL (hASL, cap11/hASL,cap0 = 0.58, P < 0.04). Capsaicin pretreatment, without histamine exposure, caused significant increases in epithelial and submucosal areas (Aepi,cap0/Aepi,norm0 = 1.23, P < 0.06; Asub,cap0/Asub,norm0 = 1.40, P < 0.01). The notation cap0 and cap11 indicates capsaicin-pretreated airways given 0 or 11 micrograms/kg histamine, respectively; similarly, norm0 and norm11 indicate normal airways given 0 and 11 micrograms/kg histamine, respectively. Histamine infusion in capsaicin-pretreated animals was associated with liquid shifts from epithelium to lamina propria and from submucosa to adventitia; however, the total wall area was similar to, if not smaller than, that in capsaicin-pretreated animals without histamine treatment. In contrast, histamine infusion in normal animals resulted in significant increases in the areas of the epithelial and lamina propria compartments (Aepi,norm11/Aepi,norm0 = 1.25, P < 0.05; Alp,norm11/Alp,norm0 = 2.19, P < 0.001) as well as a substantial increase in adventitial area, which was significantly attenuated by capsaicin pretreatment (Aadv,cap11/Aadv,norm11 = 0.40, P < 0.001). The resulting total wall area was more than twice that in normal animals without histamine treatment. Our data indicate that histamine-induced accumulation of liquid in the epithelium, lamina propria, and adventitia of normal airways is rapid in onset, most likely derives from a leaky bronchial microvasculature, and is mediated by the secondary release of neurokinins.
Roach, J. M., S. R. Muza, et al. (1996). "Urinary leukotriene E4 levels increase upon exposure to hypobaric hypoxia." Chest 110(4): 946-51.
STUDY OBJECTIVE: To determine whether urinary leukotriene E4 (uLTE4) levels increase upon exposure to high altitude, and also to ascertain the relationship between uLTE4 levels and symptoms of acute mountain sickness (AMS). DESIGN: Prospective, unblinded, single-factor (altitude) experimental study. SETTINGS: US Army research laboratory facilities at sea level ([SL] 50 m), 1,830 m, and 4,300 m. PARTICIPANTS: Eight healthy male subjects ranging in age from 19 to 24 years. MEASUREMENTS: uLTE4 levels and symptoms of AMS were measured at just above SL (50 m), 3 1/2 days after being transported from SL to moderate altitude (MA) (1,830 m), and 1 1/2 days after ascent from 1,830 to 4,300 m (high altitude [HA]). Symptoms of AMS were assessed using standard indexes derived from the Environmental Symptoms Questionnaire weighted toward cerebral (AMS-C) and respiratory (AMS-R) manifestations. Oxygen saturation was measured noninvasively by pulse oximetry at SL and HA. RESULTS: The mean (+/-SEM) uLTE4 levels (pg/mg creatinine) were 67.9 (+/-13.2) at SL; 82.3 (+/-5.5) at MA; and 134.8 (+/-19.4) at HA (p < 0.05 comparing HA with SL and MA). CONCLUSIONS: We conclude that uLTE4 levels increase shortly after exposure to HA even after staging for 4 days at MA. Although this study does not clearly demonstrate a relationship between uLTE4 levels and symptoms of AMS, it supports the hypothesis that leukotrienes may be involved in the pathophysiologic state of AMS.
Massaro, A. F., S. Mehta, et al. (1996). "Elevated nitric oxide concentrations in isolated lower airway gas of asthmatic subjects." Am J Respir Crit Care Med 153(5): 1510-4.
Previous studies have raised the possibility that the measurement of nitric oxide (NO.) concentrations in expired air may represent a noninvasive measure of lower airway inflammation. To address the question of whether the elevated NO. recovered in mixed expired air from asthmatic subjects is a reflection of the pulmonary airway microenvironment or merely nasopharyngeal contamination, mixed expired NO. determinations were performed in five normal and five asthmatic subjects before and after orotracheal intubation (thereby isolating the lower airway gas from ambient air contamination or gas conditioned in the nasopharynx). The mixed expired NO. concentrations determined in patients with asthma were significantly elevated (p < 0.05 or less) above those of normal subjects in both the pre- and postintubation samples. After intubation, mixed expired NO. levels were 4.7 +/- 1.3 ppb and 13.2 +/- 2.0 ppb in normal and asthmatic individuals, respectively; the difference in these values was statistically significant (p < 0.01). Lower airway gas, sampled through the bronchoscope during a breathhold, was found to contain NO. concentrations of 7.0 +/- 1.2 ppb and 40.5 +/- 5.6 ppb at the tracheal carina of normal and asthmatic individuals, respectively. The asthmatic values were significantly (p < 0.01) elevated above those found in normal subjects. These findings indicate that the difference in mixed expired NO. of normal subjects and asthmatics reflects a difference in NO. concentration present in the lower airway.
Massaro, A. F. and J. M. Drazen (1996). ""Exhaled nitric oxide during exercise: site of release and modulation by ventilation and blood flow"." J Appl Physiol 80(6): 1863-4.
Mansour, M., M. Karmilowicz, et al. (1996). "Production and characterization of guinea pig IL-5 in baculovirus-infected insect cells." Am J Physiol 270(6 Pt 1): L1002-7.
To study the role interleukin (IL)-5 may play in altering airway function in asthma, we have produced recombinant protein for exogenous administration to guinea pigs. The guinea pig IL-5 (gpIL-5) cDNA was cloned by polymerase chain reaction (PCR) amplification of guinea pig spleen RNA and expressed as a secretion product from recombinant baculovirus-infected Sf9 insect cell cultures. The protein was purified to homogeneity by a four-step procedure that included immunoaffinity chromatography using polyclonal antipeptide antibodies against a region of the mature secreted cytokine. The cytokine was properly processed after the signal sequence by the Sf9 cells, was glycosylated with terminal mannose-containing oligosaccharide, and had proper disulfide-linked dimer structure as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The purified preparation was active in vitro and in vivo as determined by its ability to prime human basophils to release leukotriene C4 in the presence of C5a and to induce airway eosinophilia in naive guinea pigs.
Lilly, C. M., R. W. Chapman, et al. (1996). "Effects of interleukin 5-induced pulmonary eosinophilia on airway reactivity in the guinea pig." Am J Physiol 270(3 Pt 1): L368-75.
Administration of interleukin 5 (IL-5) to guinea pigs by tracheal injection was associated with increased recovery of eosinophils and neutrophils from bronchoalveolar lavage (BAL) fluid. The number of eosinophils recovered from BAL fluid increased in a dose-dependent manner from 9 +/- 2 X 10(3)/ml to a plateau of 143 +/- 29 X 10(3)/ml after the administration of recombinant human IL-5 (rhIL-5). Tracheal administration of recombinant guinea pig IL-5 (gpIL-5) also increased eosinophil recovery but was less potent than rhIL-5. Histological analysis confirmed the presence of inflammatory cells in the lung; there were higher grades of inflammation in airway than in parenchymal tissue after gpIL-5 administration. In addition, the histological grade of airway inflammation was greater 24 and 72 h after gpIL-5 administration than it was 6 days after administration. Airway hyperresponsiveness is reported to occur in guinea pigs exposed to rhIL-5 by intraperitoneal cellular production. It is surprising that airway infiltration with eosinophils induced by the topical application of IL-5 was not associated with hyperresponsiveness to substance P, histamine, or platelet-activating factor in intact animals or to methacholine in tracheally perfused lungs. Furthermore, the microvascular leakage induced by substance P was not altered by rhIL-5 administration. These findings indicate that the presence of eosinophils alone is not sufficient for the expression of airway hyperresponsiveness. Our ability to separate eosinophil recruitment and retention in the tissues from airway hyperresponsiveness indicates that these two processes are distinct and that the presence of eosinophils in lung tissue, by itself, is not sufficient to alter airway contractile responses.
Kamada, A. K., S. J. Szefler, et al. (1996). "Issues in the use of inhaled glucocorticoids. The Asthma Clinical Research Network." Am J Respir Crit Care Med 153(6 Pt 1): 1739-48.
Israel, E., J. Cohn, et al. (1996). "Effect of treatment with zileuton, a 5-lipoxygenase inhibitor, in patients with asthma. A randomized controlled trial. Zileuton Clinical Trial Group." Jama 275(12): 931-6.
OBJECTIVE: To study the effect of 3 months of treatment with zileuton, an inhibitor of the enzymatic pathway (5-lipoxygenase) leading to leukotriene formation, on disease control in patients with mild to moderate asthma. DESIGN: Randomized, double-blind, parallel-group study in 401 patients. A 10-day placebo lead-in was followed by a double-blind treatment period of 13 weeks. SETTING: Asthma study clinics in university hospitals and private practices. PATIENTS OR OTHER PARTICIPANTS: Patients with mild to moderate asthma (forced expiratory volume in the first second [FEV1], 40% to 80% of predicted) whose only treatment was inhaled beta-agonists. INTERVENTIONS: Treatment with 600 mg or 400 mg of zileuton or placebo (each taken four times daily.) MAIN OUTCOME MEASURES: Frequency of asthma exacerbation requiring treatment with corticosteroids, use of inhaled beta-agonists, pulmonary function tests, asthma symptom assessment, and quality-of-life evaluation. Safety was evaluated by monitoring adverse events. RESULTS: Only eight (6.1%) of 132 patients receiving 600 mg of zileuton four times a day required corticosteroid treatment for asthma vs 21 (15.6%) of 135 patients receiving placebo (P=.02), giving a relative risk of 2.6. At the time of expected peak drug concentration, the average FEV1 improved 15.7% in the 600-mg zileuton group vs 7.7% in the placebo group (P=.006). Quality-of-life assessments significantly improved in the 600-mg zileuton group and not in the placebo group (P=.007 for the overall score). Elevations in liver function tests (more than three times normal), all of which reversed with drug withdrawal, occurred in five patients (P=.03 vs placebo), three patients (P=.12 vs placebo), and no patients treated with 600 mg of zileuton, 400 mg of zileuton, or placebo, respectively. CONCLUSIONS: Three months of 5-lipoxygenase inhibition produced a significant improvement in asthma control. These data indicate that 5-lipoxygenase products of arachidonic acid metabolism are mediators of inflammation with an important role in the biology of asthma.
Drazen, J. M., J. P. Arm, et al. (1996). "Sorting out the cytokines of asthma." J Exp Med 183(1): 1-5.
Drazen, J. M., E. Israel, et al. (1996). "Comparison of regularly scheduled with as-needed use of albuterol in mild asthma. Asthma Clinical Research Network." N Engl J Med 335(12): 841-7.
BACKGROUND: Inhaled beta-agonists are the most commonly used treatment for asthma, but data suggest that regularly scheduled use of these agents may have deleterious effect on the control of asthma. We compared the effects of regularly scheduled use of inhaled albuterol with those of albuterol used only as needed in patients with mild chronic, stable asthma. METHODS: In a multicenter, double-blind study, we randomly assigned 255 patients with mild asthma to inhale albuterol either on a regular schedule (126 patients) or only as needed (129 patients). The patients were followed for 16 weeks. RESULTS: The primary outcome indicator, peak expiratory air flow measured in the morning, did not change significantly during the treatment period in the scheduled (416 liters per minute after the run-in period and 414 liters per minute after the treatment period) or the as-needed (424 liters per minute at both times) treatment groups (P=0.71). There were no significant differences between the two groups in peak flow variability, forced expiratory volume in one second, the number of puffs of supplemental albuterol needed, asthma symptoms, asthma quality-of-life score, or airway responsiveness to methacholine. The statistically significant differences between the groups in evening peak flow and in the short-term bronchodilator response to inhaled albuterol were small and judged to be clinically unimportant. CONCLUSIONS: In patients with mild asthma, neither deleterious nor beneficial effects derived from the regular use of inhaled albuterol beyond those derived from use of the drug as needed. Inhaled albuterol should be prescribed for patients with mild asthma on an as-needed basis.
Drazen, J. M., S. T. Weiss, et al. (1996). "Beta 2 adrenoceptor polymorphisms." Thorax 51(11): 1168.
Asano, K., C. M. Lilly, et al. (1996). "Prostaglandin G/H synthase-2 is the constitutive and dominant isoform in cultured human lung epithelial cells." Am J Physiol 271(1 Pt 1): L126-31.
Two isoforms of prostaglandin G/H synthase (PGHS; prostaglandin endoperoxide synthase, cyclooxygenase) have been identified; PGHS-1 is expressed constitutively in most tissues, whereas PGHS-2 is thought to be induced by various proinflammatory cytokines and growth factors. In this study, we determined which isoform of PGHS mRNA, protein, and activity was present constitutively in A549 (a human lung adenocarcinoma cell line) and in untransformed (normal human bronchial epithelial or NHBE) and transformed (16HBE4o-) human bronchial epithelial cells. Two PGHS-2-specific inhibitors, NS-398 and L-745, 337, blocked the release of prostaglandin E2 from A549 cells with mean inhibitory concentrations of 5 and 18 nM, respectively, but did not inhibit its release from human bronchial smooth muscle cells (BSMC) at a concentration of 10 microM. Northern and immunoblot analysis demonstrated that BSMC expressed PGHS-1 mRNA and protein constitutively, whereas epithelial cells expressed PGHS-2 mRNA and protein constitutively with either undetectable (A549, 16HBE4o-) or very low levels (NHBE) of PGHS-1. We conclude that PGHS-2 is the dominant PGHS isoform in unstimulated and stimulated lung epithelial cells in culture.
Yager, D., R. D. Kamm, et al. (1995). "Airway wall liquid. Sources and role as an amplifier of bronchoconstriction." Chest 107(3 Suppl): 105S-110S.
Airway liquid balance in asthma is largely determined by active plasma exudation from tracheobronchial microvessels into the interstitial spaces of the mucosa, submucosa, and/or adventitia, and from there into the luminal space. This exuded plasma is rich in proteins and cell mediators capable of initiating several events, including activation of sensory neural pathways, plasma protein cleavage, inflammatory cell recruitment, and inhibition of surfactant function. It can act to amplify the bronchoconstrictor response by increasing mucosal and/or submucosal thickness, altering mechanical properties of airway wall compartments, decoupling the airway wall from parenchymal attachments, filling airway interstices, and by creating an additional inward force because of surface tension, resulting in further airway constriction and possibly closure and thereby significantly increasing airways resistance.
Rothenberg, M. E., A. D. Luster, et al. (1995). "Constitutive and allergen-induced expression of eotaxin mRNA in the guinea pig lung." J Exp Med 181(3): 1211-6.
Eotaxin is a member of the C-C family of chemokines and is related during antigen challenge in a guinea pig model of allergic airway inflammation (asthma). Consistent with its putative role in eosinophilic inflammation, eotaxin induces the selective infiltration of eosinophils when injected into the lung and skin. Using a guinea pig lung cDNA library, we have cloned full-length eotaxin cDNA. The cDNA encodes a protein of 96 amino acids, including a putative 23-amino acid hydrophobic leader sequence, followed by 73 amino acids composing the mature active eotaxin protein. The protein-coding region of this cDNA is 73, 71, 50, and 48% identical in nucleic acid sequence to those of human macrophage chemoattractant protein (MCP) 3, MCP-1, macrophage inflammatory protein (MIP) 1 alpha, and RANTES, respectively. Analysis of genomic DNA suggested that there is a single eotaxin gene in guinea pig which is apparently conserved in mice. High constitutive levels of eotaxin mRNA expression were observed in the lung, while the intestines, stomach, spleen, liver, heart, thymus, testes, and kidney expressed lower levels. To determine if eotaxin mRNA levels are elevated during allergen-induced eosinophilic airway inflammation, ovalbumin (OVA)-sensitized guinea pigs were challenged with aerosolized antigen. Compared with the lungs from saline-challenged animals, eotaxin mRNA levels increased sixfold within 3 h and returned to baseline by 6 h. Thus, eotaxin mRNA levels are increased in response to allergen challenge during the late phase response. The identification of constitutive eotaxin mRNA expression in multiple tissues suggests that in addition to regulating airway eosinophilia, eotaxin is likely to be involved in eosinophil recruitment into other tissues as well as in baseline tissue homing.
Massaro, A. F., B. Gaston, et al. (1995). "Expired nitric oxide levels during treatment of acute asthma." Am J Respir Crit Care Med 152(2): 800-3.
Nitric oxide (NO) is known to be present in measurable quantities in the exhaled air of normal subjects and at higher concentrations in asthmatic subjects not treated with glucocorticoids. We confirmed these findings by analyzing the mean mixed expired NO concentrations of 43 stable asthmatics and 90 normal subjects; NO levels were higher in the asthmatic population (13.9 parts per billion [ppb] versus 6.2 ppb, p < 0.001). Although the effects of glucocorticoids on the NO content of mixed expired air are known, it is not known if beginning systemic glucocorticoid therapy reduces exhaled NO levels in a given individual. To examine this question, seven patients needing emergency therapy for asthma underwent repeated measurements of mixed expired NO levels during their course of treatment with glucocorticoids. All patients had a reduction in mixed expired NO concentration (p = 0.002) and an accompanying improvement in airway obstruction. The decrease in exhaled NO was evident as early as 48 h after the initiation of therapy (p = 0.05). These data suggest mixed expired NO concentrations may prove useful as an index of asthma severity and treatment efficacy for an individual patient.
Lilly, C. M., T. R. Bai, et al. (1995). "Neuropeptide content of lungs from asthmatic and nonasthmatic patients." Am J Respir Crit Care Med 151(2 Pt 1): 548-53.
Tracheal and lung parenchymal SP-LI (substance P-like immunoreactivity) and VIP-LI (vasoactive intestinal peptide-like immunoreactivity) content was measured in HPLC-purified tissue extracts from patients with and without asthma. We detected significantly less SP-LI in tracheal tissue from asthmatic than from nonasthmatic patients, whereas parenchymal SP-LI content was not significantly different between these groups. This finding does not support the concept that asthmatic lungs contain excessive amounts of SP. Indeed, lower SP-LI content of tracheal tissues from asthmatic patients may reflect augmented SP release followed by degradation. We detected greater quantities of VIP-LI in tracheal than in parenchymal tissue in both groups, but did not detect significant differences in VIP-LI content in tracheal or parenchymal tissues from asthmatic and nonasthmatic patients. These findings indicate that asthmatic and nonasthmatic lungs contain similar levels of VIP.
Lilly, C. M., A. E. Hall, et al. (1995). "Substance P-induced histamine release in tracheally perfused guinea pig lungs." J Appl Physiol 78(4): 1234-41.
The capacity of substance P (SP) and endogenously released tachykinins to liberate histamine was examined in isolated tracheally perfused guinea pig lungs. Increasing doses of tracheally injected SP were associated with the recovery of increasing amounts of histamine from lung effluent. The mechanism of SP-induced histamine liberation was explored in studies with neurokinin-(NK) receptor agonists and antagonists. Tracheal injection of either the NK1 agonist [Sar9,Met(O2)11]SP or the NK2 agonist [beta-Ala8]-neurokinin A-(4-10) was associated with a significant increase in histamine recovery from lung effluent. In addition, both the NK1 antagonist CP-99994 and the NK2 antagonist SR-48968 significantly inhibited SP-induced histamine release. These findings support the hypothesis that SP can liberate histamine from guinea pigs lungs by a mechanism that depends predominantly on NK1- and NK2-receptor activation. The liberation of endogenous tachykinins by acute tracheal injection of capsaicin was also associated with augmented histamine recovery, which was inhibited by combined NK1- and NK2-receptor blockade. Tracheal injection of SP was associated with an increase in the percentage of airway mast cells exhibiting histological evidence of degranulation. This study demonstrates that exogenous SP, as well as endogenous tachykinins released from capsaicin-sensitive neurons, can liberate histamine, most likely from airway mast cells, by a mechanism that depends predominantly on the activation of NK1 and NK2 receptors.
Fischer, A. R., C. A. McFadden, et al. (1995). "Effect of chronic 5-lipoxygenase inhibition on airway hyperresponsiveness in asthmatic subjects." Am J Respir Crit Care Med 152(4 Pt 1): 1203-7.
The leukotrienes are known bronchoactive agonists with potential proinflammatory effects that may be involved in mediating airway hyperresponsiveness. We investigated the effects of zileuton, an inhibitor of 5-lipoxygenase (5-LO), on airway responsiveness to cold, dry air in patients with moderate asthma. A group of 10 asthmatic patients underwent cold, dry air hyperventilation challenge; challenges were performed before drug treatment and 1 to 10 d after the completion of treatment with study drugs. The cold air minute ventilation required to cause a 15% decrease in FEV1 (PD15 VE) increased by 58% compared with the response before treatment, 1 to 10 d after the completion of 13 wk of treatment with zileuton. The geometric mean (geometric mean/SEM and geometric mean x SEM) PD15 VE increased from 24.5 (20.4, 29.5) L/min to 38.8 (34.7, 43.7) L/min (p = 0.01). Zileuton treatment inhibited 5-LO as measured ex vivo by ionophore-stimulated LTB4 levels in whole blood. In four of seven subjects, LTB4 levels before zileuton ingestion fell from 110.88 +/- 25.42 to 5.40 +/- 1.95 ng/ml 2 h post-zileuton dosing (p = 0.02, pre- versus 2 h postzileuton ingestion). Consistent with the short half-life of zileuton, 6 h postzileuton dosing the ionophore-stimulated, LTB4 levels in whole blood had increased to 89.68 +/- 35.54 ng/ml (p = 0.41, pre- versus 6 h postzileuton ingestion). Based on the first-order kinetics of zileuton, its effect on 5-LO activity should have been dissipated less than 16 h postingestion. Thus, chronic zileuton treatment decreased airway hyperresponsiveness as determined by reactivity to cold, dry air.(ABSTRACT TRUNCATED AT 250 WORDS)
Drazen, J. M., B. Gaston, et al. (1995). "Chemical regulation of pulmonary airway tone." Annu Rev Physiol 57: 151-70.
Over the past three years, substantial progress has been made in dissecting out the role of each of these individual effector systems, namely, the leukotrienes, neuropeptides, and nitrogen oxides. The next major challenge is to understand how they function in an integrated fashion.
Drazen, J. M. and E. Israel (1995). "Treatment of chronic stable asthma with drugs active on the 5-lipoxygenase pathway." Int Arch Allergy Immunol 107(1-3): 319-20.
It is now established that 5-lipoxygenase products are synthesized and released in the airway during asthmatic reactions. The importance of these products in the asthmatic response has been established through study of the effects of 5-lipoxygenase inhibitors and leukotriene D4 receptor antagonists in patients with chronic stable asthma. In this study we review the data demonstrating that chronic administration of zileuton, an inhibitor of 5-lipoxygenase, is associated with improved airway function, decreased asthma symptoms and decreased need for asthma medication use in patients with mild to moderate asthma.
Drazen, J. M. and G. M. Turino (1995). "Progress at the interface of inflammation and asthma. Report of an ATS-sponsored workshop November, 1993." Am J Respir Crit Care Med 152(1): 386-7.
Most attendees agreed that the workshop achieved it goal of bringing together individuals with a number of distinct scientific approaches to consider new ways of thinking about asthma.
Drazen, J. M., J. F. Evans, et al. (1995). "Inflammatory effector mechanisms in asthma." Am J Respir Crit Care Med 152(1): 403-7.
Each of these effector systems has the capacity to initiate airway obstruction or alter airway responsiveness in asthma. It is likely that they act in concert in certain asthmatic settings. Further basic and applied research will define their relative roles in asthma.
De Sanctis, G. T., M. Merchant, et al. (1995). "Quantitative locus analysis of airway hyperresponsiveness in A/J and C57BL/6J mice." Nat Genet 11(2): 150-4.
Airway hyperresponsiveness is a key characteristic of human asthma and a marker for asthma-like conditions in animals. F1 mice derived from A/J and C57BL/6J display a phenotype which resembles the asthma-like phenotype of the A/J mice. Since airway responsiveness failed to segregate as a mendelian trait, we show significant linkage at two loci, Bhr1 (lod = 3.0) and Bhr2 (lod = 3.7) on chromosomes 2 and 15. A third locus, Bhr3 (lod = 2.83), maps to chromosome 17. Each of these loci maps near candidate loci implicated in the pathobiology of asthma. Our study represents the first linkages established through a genome-wide survey of airway hyperresponsiveness in any mammal.
Coleman, R. A., R. M. Eglen, et al. (1995). "Prostanoid and leukotriene receptors: a progress report from the IUPHAR working parties on classification and nomenclature." Adv Prostaglandin Thromboxane Leukot Res 23: 283-5.
Asano, K., C. M. Lilly, et al. (1995). "Diurnal variation of urinary leukotriene E4 and histamine excretion rates in normal subjects and patients with mild-to-moderate asthma." J Allergy Clin Immunol 96(5 Pt 1): 643-51.
BACKGROUND: Leukotriene E4 (LTE4) and histamine excreted into the urine reflect the in vivo synthesis and release of cysteinyl leukotrienes and histamine, respectively. We examined the diurnal variation of the excretion rate of these mediators over 4 consecutive days in normal subjects (n = 5) and patients with stable mild-to-moderate asthma (n = 8). METHODS: Sixteen consecutive 6-hour urine samples were collected over 4 days. Urinary LTE4 concentrations were determined by reverse-phase high-pressure liquid chromatography, followed by ELISA. Urinary histamine concentrations were measured by ELISA. The excretion rates of these compounds were normalized relative to urinary creatinine content. RESULTS: The mean urinary LTE4 excretion rate was 83.8 +/- 38.2 pg/mg creatinine (mean +/- SD) in normal subjects; in patients with asthma, the urinary LTE4 excretion rate (110.0 +/- 59.2 pg/mg creatinine) was significantly higher than that in normal subjects (p < 0.05). The urinary histamine excretion rate was not different between normal subjects (24.0 +/- 12.5 ng/mg creatinine) and patients with asthma (31.5 +/- 25.8 ng/mg creatinine). A robust and systematic within-day variation (p < 0.01), but no day-to-day variation, was observed in histamine excretion rate. Although the magnitude of variation in LTE4 excretion within a day was significantly greater in patients with asthma than in normal subjects (p < 0.05), we could not identify any specific diurnal variation pattern in either the normal or the asthma group. No significant correlation was observed between urinary LTE4 and histamine excretion rate within any subject. CONCLUSIONS: Patients with asthma excrete LTE4 in the urine at a greater rate than normal subjects. Although no systematic variation in urinary LTE4 excretion rates over the course of a day was observed in either normal subjects or patients with stable asthma, the presence of a systematic diurnal variation of urinary histamine excretion exists in both groups.
Yager, D., T. Cloutier, et al. (1994). "Airway surface liquid thickness as a function of lung volume in small airways of the guinea pig." J Appl Physiol 77(5): 2333-40.
The average thickness and distribution of airway surface liquid (ASL) on the luminal surface of peripheral airways were measured in normal guinea pig lungs frozen at functional residual capacity (FRC) and total lung capacity (TLC). Tissue blocks containing cross sections of airways of internal perimeter 0.188-3.342 mm were cut from frozen lungs and imaged by low-temperature scanning electron microscopy (LTSEM). Measurements made from LTSEM images were found to be independent of freezing rate by comparison of measurements at rapid and slow freezing rates. At both lung volumes, the ASL was not uniformly distributed in either the circumferential or longitudinal direction; there were regions of ASL where its thickness was < 0.1 micron, whereas in other regions ASL collected in pools. Discernible liquid on the surfaces of airways frozen at FRC followed the contours of epithelial cells and collected in pockets formed by neighboring cells, a geometry consistent with a low value of surface tension at the air-liquid interface. At TLC airway liquid collected to cover epithelial cells and to form a liquid meniscus, a geometry consistent with a higher value of surface tension. The average ASL thickness (h) was approximately proportional to the square root of airway internal perimeter, regardless of lung volume. For airways of internal perimeter 250 and 1,800 microns, h was 0.9 and 1.8 microns at FRC and 1.7 and 3.7 microns at TLC, respectively. For a given airway internal perimeter, h was 1.99 times thicker at TLC than at FRC; the difference was statistically significant (P < 0.01; 95% confidence interval 1.29-3.08).(ABSTRACT TRUNCATED AT 250 WORDS)
Vasconcellos, C. A., P. G. Allen, et al. (1994). "Reduction in viscosity of cystic fibrosis sputum in vitro by gelsolin." Science 263(5149): 969-71.
Obstruction of airways by viscous sputum causes lung damage in patients with cystic fibrosis (CF). Sputum samples from CF patients were shown to contain filamentous actin. Human plasma gelsolin, a protein that severs actin filaments, rapidly decreased the viscosity of CF sputum samples in vitro. Gc globulin and deoxyribonuclease I, proteins that sequester monomeric actin but do not sever actin filaments, were less efficient than gelsolin in diminishing sputum viscosity. These results suggest that gelsolin may have therapeutic potential as a mucolytic agent in CF patients.
Oettgen, H. C., T. R. Martin, et al. (1994). "Active anaphylaxis in IgE-deficient mice." Nature 370(6488): 367-70.
The IgE-triggered release of mast cell mediators in response to antigen is thought to be the primary event in immediate hypersensitivity reactions such as systemic anaphylaxis. Although mast cells and basophils can be activated in vitro by non-IgE stimuli, it is not known whether these triggers lead to physiological changes in vivo. To investigate this possibility, we generated mice with a homozygous null mutation of the C epsilon gene. Such mice make no IgE, but produce other immunoglobulin isotypes normally. We report that despite the IgE deficiency, sensitized mutant mice become anaphylactic on antigen challenge and display tachycardia and pulmonary function changes similar to those seen in wild-type animals. These responses are accompanied by vascular leak, sharply elevated plasma histamine and rapid death. IgE-independent anaphylaxis does not depend on complement activation, but, as indicated in studies using genetically immunodeficient RAG-2- and SCID mice, does require a functional immune system. Such results clearly demonstrate that non-IgE pathways for hypersensitivity reactions exist in mice.
Martin, T. R., M. L. Cohen, et al. (1994). "Serotonin-induced pulmonary responses are mediated by the 5-HT2 receptor in the mouse." J Pharmacol Exp Ther 268(1): 104-9.
C57BL/6 mice exhibit acute transient decreases in lung conductance (GL) and dynamic compliance (Cdyn) after intravenous administration of serotonin (5-HT). To identify the specific agonist receptor subtypes responsible for this bronchoconstriction, we measured changes in pulmonary function in C57BL/6 mice in response to intravenous infusion of 5-HT receptor subtype-selective agonists and to 5-HT in the presence of antagonists selective for the 5-HT2 or 5-HT3 receptor subtypes. Agonists selective for the 5-HT1A/1B/1D or 5-HT3 receptor subtypes induced minimal or undetectable pulmonary responses, whereas infusion of alpha-methyl-5-hydroxytryptamine, a 5-HT2 receptor-selective agonist, led to dose-related decreases in Cdyn and GL. The selective 5-HT3 receptor antagonist, LY278584 maleate, (1.0 mg/kg i.v.) caused no detectable reduction in the response to 100 micrograms/kg of 5-HT. In contrast, treatment with the 5-HT2 receptor antagonist LY53857 (10 micrograms/kg i.v.) resulted in a significant diminution of the pulmonary response observed after infusion of 100 micrograms/kg of 5-HT. Dose-response relationships were established for 5-HT in experiments in which each mouse was treated with a single dose of 5-HT without antagonist or after LY53857. Compared with responses to doses of 5-HT of more than 100 micrograms/kg in the absence of antagonist, pulmonary responses to 5-HT after infusion of 10 micrograms/kg of LY53857 were significantly reduced; 100 micrograms/kg of LY53857 nearly abolished the responses to all doses of 5-HT.(ABSTRACT TRUNCATED AT 250 WORDS)
Lilly, C. M., G. Besson, et al. (1994). "Capsaicin-induced airway obstruction in tracheally perfused guinea pig lungs." Am J Respir Crit Care Med 149(5): 1175-9.
The neurokinin receptors responsible for transducing the airway obstruction resulting from capsaicin infusion were defined in the tracheally perfused guinea pig lung. In this lung preparation, buffer is perfused via the trachea and allowed to exit the lung through numerous small holes in the pleural surface; airway obstruction is monitored as the backpressure (Pao) generated at a constant perfusion flow rate. Infusion of the specific NK1 receptor agonist, Sar-9 Met02(11) substance P, resulted in an increase in Pao; this effect was prevented by the NK1 receptor antagonist CP 99,994 but not by the NK2 receptor antagonist SR 48,968. Infusion of the specific NK2 receptor agonist Nle10-neurokinin A 4-10 resulted in an increase in Pao; this effect was prevented by the NK2 receptor antagonist SR 48,968 but not by the NK1 receptor antagonist CP 99,994. In the absence of NK receptor antagonists, infusion of capsaicin resulted in a significant increase in Pao, 31 +/- 4 cm H2O. In the presence of the NK1 receptor antagonist, the capsaicin response was not diminished, but in the presence of the NK2 receptor antagonist, the Pao response diminished to only 10 +/- 2 cm H2O, p < 0.001. These data indicate that when capsaicin is presented to the epithelial surface of the lung the resulting airway obstruction is mediated predominantly by NK2 receptor stimulation.
Lilly, C. M., L. Kobzik, et al. (1994). "Effects of chronic airway inflammation on the activity and enzymatic inactivation of neuropeptides in guinea pig lungs." J Clin Invest 93(6): 2667-74.
The effects of airway inflammation induced by chronic antigen exposure on substance P (SP)-induced increases and vasoactive intestinal peptide (VIP)-induced decreases in airway opening pressure (Pao), and the recovery of intact and hydrolyzed radiopeptide were studied in tracheally perfused guinea pig lungs. SP (10(-6) mol/kg) induced a significantly greater increase in Pao in lungs from antigen-exposed (30 +/- 5 cm H2O) than saline-exposed animals (15 +/- 1 cm H2O, P < 0.05). Significantly more intact 3H-SP and significantly less 3H-SP 1-7, a neutral endopeptidase (NEP) hydrolysis product, were recovered from the lung effluent of antigen-exposed than saline-exposed animals (P < 0.05). Injection of VIP (10(-9) mol/kg) induced significantly more pulmonary relaxation in saline-exposed compared with antigen-exposed lungs (62 +/- 4%, P < 0.001). In contrast to effluent from saline-exposed animals, lung effluent from antigen-exposed lungs contained less intact VIP, increased amounts of a tryptic hydrolysis product, and no products consistent with the degradation of VIP by NEP. These data indicate that inflamed lungs are more sensitive to the contractile effects of SP because it is less efficiently degraded by NEP and are less sensitive to the relaxant effects of VIP because it is more efficiently degraded by a tryptic enzyme. Changes in airway protease activity occur with allergic inflammation and may contribute to airway hyperresponsiveness.
Israel, E. and J. M. Drazen (1994). "Treating mild asthma--when are inhaled steroids indicated?" N Engl J Med 331(11): 737-9.
Goodman, D. E., E. Israel, et al. (1994). "The influence of age, diagnosis, and gender on proper use of metered-dose inhalers." Am J Respir Crit Care Med 150(5 Pt 1): 1256-61.
Metered dose inhalers (MDIs) are widely used in clinical practice for administering pharmaceuticals targeted to the lung. It is well known that the inhalation technique used with MDIs can substantially influence the clinical response to inhaled medications. To determine the acceptability of MDI maneuvers, we studied 59 subjects (26 females and 33 males; age, 20 to 81 yr; mean age, 38 yr) to determine whether the MDI technique used by these individuals complied with published recommendations for acceptable inhalation technique. Measurements were made with an MDI adapter that contained an unobtrusive, lightweight, miniature sensing system. Inspiratory flow at the moment of MDI actuation (Va), the volume (integrated from airflow) at actuation as a fraction of total inspiratory volume (Va/VI), breath-holding time (tBH), and inspiratory volume as a fraction of FVC (VI/FVC) were determined from 59 uncoached inhalations. We defined an acceptable maneuver, based on published data, by four components: (1) inspiratory flow at actuation (Va) between 25 and 90 L/min; (2) actuation during early inspiration (0 < Va/VI < or = 0.20); (3) adequate breath-holding time (tBH > 4 s), and (4) a deep inhalation (VI/FVC > 0.50). For all subjects, only 25% of inhalation maneuvers met all four criteria for acceptability. We found that a significantly higher proportion of male than female subjects performed an acceptable MDI maneuver (43% versus 4%, p < 0.001). There were no significant differences in technique between younger and older subjects or between patients with a diagnosis of asthma or chronic obstructive pulmonary disease (COPD). We conclude that most patients use their MDIs incorrectly; females of all ages are much more likely to have improper MDI technique than are males.
Gaston, B., J. M. Drazen, et al. (1994). "The biology of nitrogen oxides in the airways." Am J Respir Crit Care Med 149(2 Pt 1): 538-51.
Nitrogen oxides (NOx), regarded in the past primarily as toxic air pollutants, have recently been shown to be bioactive species formed endogenously in the human lung. The relationship between the toxicities and the bioactivities of NOx must be understood in the context of their chemical interactions in the pulmonary microenvironment. Nitric oxide synthase (NOS) is a newly identified enzyme system active in airway epithelial cells, macrophages, neutrophils, mast cells, autonomic neurons, smooth muscle cells, fibroblasts, and endothelial cells. The chemical products of NOS in the lung vary with disease states, and are involved in pulmonary neurotransmission, host defense, and airway and vascular smooth muscle relaxation. Further, certain patients with pulmonary hypertension, adult respiratory distress syndrome and asthma may experience physiologic improvement with NOx therapy, including inhalation of nitric oxide (NO.) gas. Both endogenous and exogenous NOx react readily with oxygen, superoxide, water, nucleotides, metalloproteins, thiols, amines, and lipids to form products with biochemical actions ranging from bronchodilation and bacteriostasis (S-nitrosothiols) to cytotoxicity and pulmonary capillary leak (peroxynitrite), as well as those with frank mutagenic potential (nitrosamines). Recent discoveries demonstrating the relevance of these species to the lung have provided new insights into the pathophysiology of pulmonary disease, and they have opened a new horizon of therapeutic possibilities for pulmonary medicine.
Gaston, B., J. M. Drazen, et al. (1994). "Relaxation of human bronchial smooth muscle by S-nitrosothiols in vitro." J Pharmacol Exp Ther 268(2): 978-84.
S-Nitrosothiols (RS-NO) relax tracheal smooth muscle from a variety of animal species, and may have physiological relevance. We therefore studied their effects on human bronchial smooth muscle. S-Nitroso adducts of glutathione, cysteine, N-acetylcysteine and bovine serum albumin relaxed tissues contracted with methacholine with mean IC50 +/- S.E.M. of 3.3 (+/- 14), 22 (+/- 45), 25 (+/- 22) and 36 (+/- 7.1) microM, respectively; they were more potent as inhibitory agonists than the corresponding reduced thiol, NaNO2, or theophylline, but less potent than isoproterenol (P < .001). Despite large differences in their molecular weights and dissociation kinetics, the IC50 of these RS-NO did not differ significantly from one another, from nitric oxide (NO.) or from sodium nitroprusside. Consistent with the role of cyclic GMP (cGMP) in mediating relaxation responses, S-nitroso-N-acetyl cysteine (S-NO-AC) (100 microM) increased tissue cGMP levels 4-fold, and 8-bromo-cGMP caused modest tissue relaxation which was potentiated by the phosphodiesterase inhibitor, dipyridamole (1 microM). However, the guanylyl cyclase inhibitors, methylene blue (100 microM) and LY 83583 (50 microM), failed to modify the relaxation response to S-NO-AC (sodium nitroprusside and NO.), while altering the accumulation of cGMP. Further, hemoglobin (100 microM) failed to inhibit relaxation by S-NO-AC.(ABSTRACT TRUNCATED AT 250 WORDS)
Fischer, A. R., M. A. Rosenberg, et al. (1994). "Direct evidence for a role of the mast cell in the nasal response to aspirin in aspirin-sensitive asthma." J Allergy Clin Immunol 94(6 Pt 1): 1046-56.
BACKGROUND: A subset of patients with asthma experience adverse nasoocular reactions after ingestion of aspirin or agents that inhibit cyclooxygenase. Recent evidence has implicated the leukotrienes in the nasoocular reaction, but the cellular sources and mechanism of activation are unknown. We used nasal lavage with and without a 5-lipoxygenase inhibitor, zileuton, to define the role of leukotrienes and to profile nasal cellular activation during this reaction. METHODS: A group of eight patients with asthma shown to have adverse reactions to aspirin documented by a 15% or greater decrease in forced expiratory volume in 1 second, accompanied by an elevation in urinary leukotriene E4 after ingestion of aspirin, received aspirin or placebo in a study with a crossover design. Nasal symptoms and nasal tryptase, histamine, leukotriene, and eosinophil cationic protein levels were evaluated. Serum tryptase and urinary histamine levels were also assessed. Subjects were then randomized to receive a week of treatment with zileuton or placebo, according to a double-blind, crossover design followed by aspirin challenge and measurement of the same mediators. RESULTS: Aspirin ingestion produced a marked increase in nasal symptoms from a baseline symptom score of 2.1 +/- 0.7 to a maximum of 8.4 +/- 1.2 (p < 0.0007). Aspirin ingestion produced a mean maximal increase in nasal tryptase of 3.5 +/- 2.6 ng/ml, whereas placebo ingestion produced a mean maximal increase of 0.1 +/- 0.2 ng/ml (p < 0.05, aspirin vs placebo). Mean maximal nasal histamine increased 1.73 +/- 1.16 ng/ml versus 0.08 +/- 0.08 ng/ml from baseline (p < 0.05, aspirin vs placebo). Aspirin produced a mean maximal increase in nasal leukotriene value of 152 pg/ml versus a 16 pg/ml decrease after placebo ingestion (p < 0.05). Zileuton treatment blocked the increase in nasal symptoms after aspirin ingestion (maximum nasal symptom score of 1.6 +/- 0.6 with zileuton vs 5.5 +/- 0.9 with placebo [p < 0.0053]). It also blocked the rise in nasal tryptase (p = 0.011) and nasal leukotriene (p < 0.05) levels after aspirin ingestion. Zileuton treatment had no significant effect on the recovery of nasal histamine. CONCLUSION: The increase in nasal symptoms in aspirin-sensitive patients with asthma after aspirin ingestion is associated with increases in nasal tryptase, histamine, and cysteinyl leukotriene levels. This mediator profile is consistent with mast cell activation during the nasal response to aspirin and suggests that 5-lipoxygenase products are essential for the nasal response to aspirin.
Drazen, J. M., C. M. Lilly, et al. (1994). "Role of cysteinyl leukotrienes in spontaneous asthmatic responses." Adv Prostaglandin Thromboxane Leukot Res 22: 251-62.
Asano, K., C. B. Chee, et al. (1994). "Constitutive and inducible nitric oxide synthase gene expression, regulation, and activity in human lung epithelial cells." Proc Natl Acad Sci U S A 91(21): 10089-93.
Histochemical activity and immunoreactivity of nitric oxide synthase (NOS, EC 126.96.36.199) have been recently demonstrated in human lung epithelium. However, the molecular nature of NOS and the regulation and function of the enzyme(s) in the airway is not known. A549 cells (human alveolar type II epithelium-like), BEAS 2B cells (transformed human bronchial epithelial cells), and primary cultures of human bronchial epithelial cells all exhibited constitutive NOS activity that was calcium dependent and inhibitable by the NOS inhibitor NG-monomethyl-L-arginine. Nitric oxide production by epithelial cells was enhanced by culture in the presence of interferon gamma, interleukin 1 beta, tumor necrosis factor alpha, and lipopolysaccharide; the NOS activity expressed under these conditions showed less dependence on calcium, reminiscent of other inducible forms of NOS. Two distinct NOS mRNA species, homologous to previously identified constitutive brain (type I) and inducible hepatic (type II) NOS, were demonstrated by reverse transcription-polymerase chain reaction in all cell lines. Northern analysis confirmed the expression of inducible NOS mRNA. Cell culture with epidermal growth factor, a principal regulator of epithelial cell function, decreased inducible NOS activity by posttranscriptional action but did not affect constitutive NOS activity. The coexistence of constitutive and inducible NOS in human alveolar and bronchial epithelial cells is consistent with a complex mechanism evolved by epithelial cells to protect the host from microbial assault at the air/surface interface while shielding the host from the induction of airway hyperreactivity.
Wetmore, L. A., C. Gerard, et al. (1993). "Human lung expresses unique gamma-glutamyl transpeptidase transcripts." Proc Natl Acad Sci U S A 90(16): 7461-5.
gamma-Glutamyl transpeptidase (EC 188.8.131.52, gamma GT) is a membrane-bound ectoenzyme that plays an important role in the metabolism of glutathione. It is composed of two subunits, both of which are encoded by a common mRNA. We examined the expression of gamma GT in human lung tissue by Northern blot analysis and screening a cDNA library made from human lung poly(A)+ RNA. Our results show that there are two gamma GT mRNA populations in human lung tissue. We define these as group I (2.4 kb) and group II (approximately 1.2 kb) transcripts. In the present communication, we characterize the unique lung transcript. Sequence analysis of representative clones shows that group I transcripts are virtually identical to those previously isolated from liver and placenta but possess a unique 5' untranslated region. In marked contrast, group II transcripts appear to be human-lung-specific. Group II transcripts appear on Northern blots probed with full-length or 3'-biased gamma GT cDNA. Sequence analysis of group II clones shows them to be homologous with group I clones in the region that encodes the reading frame for the light chain; however, they possess a series of unique 5' untranslated regions, which suggests that they arise from lung-specific message processing. Additionally, approximately 50% of the isolated group II clones contain 34 nt substitutions compared with the "wild-type" gamma GT transcripts. These data indicate that human lung expresses unique gamma GT transcripts of unknown function as well as the classical form. The abundant group II transcripts may encode part of a heterodimer related to gamma GT or represent processed lung-specific pseudogenes.
Shore, S. A., C. Sharpless, et al. (1993). "Bronchoconstrictor activities of NP gamma and NPK in anaesthetized guinea-pigs: effect on NEP inhibition." Pulm Pharmacol 6(2): 143-7.
The effects of rapid intravenous infusions of gamma-preprotachykinin-(72-92)-peptide amide (neuropeptide gamma) or beta-preprotachykinin-(72-107)-peptide amide (neuropeptide K), two N-terminally extended forms of neurokinin A (NKA), on pulmonary mechanics were examined in anaesthetized mechanically ventilated guinea-pigs. Neuropeptide gamma (NP gamma) and neuropeptide K (NPK) each caused dose-related decreases in pulmonary conductance (GL). The rank order of potency as bronchoconstrictors for the three peptides was NPK > NP gamma > NKA. Pretreatment of guinea-pigs with the neutral endopeptidase (NEP) inhibitor SCH32615 (1 mg/kg iv) decreased the doses of NP gamma and NKA required to cause a 50% decrease in GL by 3.8- and 4.9-fold respectively, but did not significantly alter NPK-induced bronchoconstriction. In animals without SCH32615, the time course of bronchoconstriction was similar for NKA and NP gamma, but NPK caused significantly more prolonged changes in GL. SCH32615 did not alter the time course of bronchoconstriction induced by NKA or NPK, but prolonged the changes in GL induced by NP gamma. The results indicate that post-translational processing of gamma- and beta-preprotachykinin mRNAs to yield NP gamma and NPK instead of NKA results in an enhanced duration of effect and an increase in bronchoconstrictor potency.
Shore, S. A., M. A. Martins, et al. (1993). "Pulmonary mechanical responses to intravenously administered capsaicin in guinea-pigs: effect of peptidase inhibitors." Pulm Pharmacol 6(3): 193-9.
In order to examine the role of peptidases in modulating bronchoconstrictor responses to i.v. administered capsaicin, a potent C-fiber stimulant, we measured changes in pulmonary conductance (GL) and dynamic compliance (Cdyn) in anesthetized mechanically ventilated guinea-pigs. Control guinea-pigs, and guinea-pigs treated with the neutral endopeptidase (NEP) inhibitors thiorphan (1.7 mg/kg) or SCH32615 (1 mg/kg), the angiotensin converting enzyme (ACE) inhibitor captopril (5.7 mg/kg), or combinations of NEP and ACE inhibitors, were given increasing doses of capsaicin by rapid i.v. injection. The doses of capsaicin required to cause a 50% decrease in GL and Cdyn (ED50GL and ED50Cdyn respectively) were computed for each animal. None of the peptidase inhibitors, when given alone, had any effect on the changes in pulmonary mechanics induced by capsaicin. However, combined administration of thiorphan and captopril, or SCH32615 and captopril, caused a decrease in ED50Cdyn for capsaicin, and prolonged the time during which the peak changes in GL induced by capsaicin persisted. These data support the hypothesis that substances whose degradation is inhibited by combined NEP and ACE inhibitors contribute to the bronchoconstriction induced by iv administered capsaicin. This profile of enzymatic degradation is consistent with the tachykinin, substance P.
Martin, T. R., T. Takeishi, et al. (1993). "Mast cell activation enhances airway responsiveness to methacholine in the mouse." J Clin Invest 91(3): 1176-82.
Mast cell-deficient mutant mice and their normal littermates were used to determine whether activation of mast cells by anti-IgE enhances airway responsiveness to bronchoactive agonists in vivo. Pulmonary conductance was used as an index of airway response as the mice were challenged with increasing intravenous doses of methacholine (Mch) or 5-hydroxytryptamine (5-HT). Mast cell activation with anti-IgE enhanced pulmonary responsiveness to Mch in both types of normal mice (P < 0.0001 by analysis of variance) but not in either genotype of mast cell-deficient mouse. Additionally, anti-IgE pretreatment of genetically mast cell-deficient W/Wv mice whose mast cell deficiency had been repaired by infusion of freshly obtained bone marrow cells or bone marrow-derived cultured mast cells from congenic normal mice led to significant (P < 0.0001) enhancement of Mch responsiveness. 5-HT responsiveness was not significantly influenced by anti-IgE pretreatment in any of the mice studied. The data support the hypothesis that IgE-mediated activation of mast cells enhances pulmonary responsiveness to cholinergic stimulation.
Martin, T. R., A. Ando, et al. (1993). "Mast cells contribute to the changes in heart rate, but not hypotension or death, associated with active anaphylaxis in mice." J Immunol 151(1): 367-76.
The mast cell is widely thought to contribute importantly to the cardiopulmonary changes associated with anaphylaxis, but much of the evidence for this is indirect. We, therefore, performed a detailed assessment of heart rate and pulmonary function during active anaphylaxis in genetically mast cell-deficient W/Wv or S1/S1d mice, the congenic normal (+/+) mice, and W/Wv mice repaired of their mast cell deficiency by transplantation of bone marrow from the congenic +/+ mice (+/+ BM-->W/Wv mice). For all five groups of mice, Ag challenge resulted in the death of more than two-thirds of the sensitized animals, whereas none of the nonsensitized control mice died as a result of Ag infusion. Sensitized normal (WBB6F1(-)+/+ or WCB6F1(-)+/+) mice and +/+BM-->W/Wv mice developed increases in heart rate that were significantly greater than those of nonsensitized +/+ mice or those of sensitized mast cell-deficient mice, indicating that mast cells contribute to the tachycardia observed in this form of active anaphylaxis. By contrast, even though some of the pulmonary changes associated with active anaphylaxis were more severe in +/+ than in mast cell-deficient mice, it was not clear to what extent this difference was mast cell dependent. W/Wv mice undergoing active anaphylaxis developed decreases in systemic arterial blood pressure that occurred more rapidly and were more severe than those observed in the congenic +/+ mice, indicating that the hypotension associated with this model of anaphylaxis also can occur by mast cell-independent mechanisms. We conclude that in this model of anaphylaxis mast cells: 1) are required for the development of the tachycardia response; 2) may contribute to, but are not essential for, production of decreases in lung function; and 3) are not necessary for the development of hypotension or death.
Lilly, C. M., M. A. Martins, et al. (1993). "Peptidase modulation of vasoactive intestinal peptide pulmonary relaxation in tracheal superfused guinea pig lungs." J Clin Invest 91(1): 235-43.
The effects of enzyme inhibitors on vasoactive intestinal peptide (VIP)-induced decreases in airway opening pressure (PaO) and VIP-like immunoreactivity (VIP-LI) recovery were studied in isolated tracheal superfused guinea pig lungs. In the absence of inhibitors, VIP 0.38 (95% CI 0.33-0.54) nmol/kg animal, resulted in a 50% decrease in PaO and 33% of a 1 nmol/kg VIP dose was recovered as intact VIP. In the presence of two combinations of enzyme inhibitors, SCH 32615 (S, 10 microM) and aprotinin (A, 500 tyrpsin inhibitor units [TIU]/kg) or S and soybean trypsin inhibitor (T, 500 TIU/kg), VIP caused a significantly greater decrease in PaO and greater quantities of VIP were recovered from lung effluent (both P < 0.001). The addition of captopril, (3 microM), leupeptin (4 microM), or bestatin (1 microM) failed to further increase pulmonary relaxation or recovery of VIP-LI. When given singly, A, T, and S did not augment the effects or recovery of VIP. The efficacy of S (a specific inhibitor of neutral endopeptidase [NEP]) and A and T (serine protease inhibitors) thus implicated NEP and at least one serine protease as primary modulators of VIP activity in the guinea pig lung. We sought to corroborate this finding by characterizing the predominant amino acid sites at which VIP is hydrolized in the lung. When [mono(125I)iodo-Tyr10]VIP was offered to the lung, in the presence and absence of the active inhibitors, cleavage products consistent with activity by NEP and a tryptic enzyme were recovered. These data demonstrate that NEP and a peptidase with an inhibitor profile and cleavage pattern compatible with a tryptic enzyme inactivate VIP in a physiologically competitive manner.
Lilly, C. M., J. M. Drazen, et al. (1993). "Peptidase modulation of airway effects of neuropeptides." Proc Soc Exp Biol Med 203(4): 388-404.
SP and NKA are potent endogenous bronchoconstrictors, whereas VIP is a potent endogenous bronchodilator. There is abundant evidence that these neuropeptides are released in the lung in a variety of conditions and that they have the capacity to modulate the bronchoactivity of the same stimuli that release them. On many occasions, their bronchoactive effects are masked by their degradation at or near the site of their release. However, when the microenvironment is modified to decrease their cleavage, they can express enhanced physiologic effects. Although it appears that the human asthmatic lung may be an environment in which the effects of neuropeptides can be amplified, the role of neuropeptides in the pathogenesis of airway obstruction remains speculative.
Lilly, C. M., J. S. Stamler, et al. (1993). "Modulation of vasoactive intestinal peptide pulmonary relaxation by NO in tracheally superfused guinea pig lungs." Am J Physiol 265(4 Pt 1): L410-5.
The mechanism of vasoactive intestinal peptide (VIP)-induced pulmonary relaxation in tracheally perfused guinea pig lungs was defined with the use of inhibitors of nitric oxide synthase (NOS) and by direct measurement of nitric oxide (NO) equivalents recovered from lung perfusion fluid. Lungs treated with 200 microM NG-nitro-L-arginine were resistant to the relaxant effects of VIP in these lungs; the 50% inhibitory dose (ID50) for VIP was 32 nmol/kg (95% confidence interval, 16-79), which was approximately 100-fold greater than the ID50 of control lungs which was 0.39 nmol/kg, (0.16-0.79, P < 0.0001). This inhibitory effect could be overcome with excess L- but not D-arginine. In contrast, VIP-induced relaxation of isolated guinea pig trachea was not modified by inhibitors of NOS. To confirm that VIP infusion resulted in NO generation in whole lungs, we measured NO equivalents in lung effluent by two distinct technologies. We found that VIP injection caused a significant increase in NO equivalents from 0.11 +/- 0.04 microM to 0.78 +/- 0.15 microM (P < 0.05) and that this increase preceded VIP-induced pulmonary relaxation. Lungs pretreated with the putative guanylyl cyclase inhibitor methylene blue were less responsive to VIP [ID50 4.0 nmol/kg (1.5-10), P < 0.005 compared with control lungs], consistent with a physiologically significant guanosine 3',5'-cyclic monophosphate-dependent mechanism. Our data demonstrate that VIP has the capacity to relax whole lungs in part by stimulating the generation of NO.
Levy, B. D., S. Bertram, et al. (1993). "Agonist-induced lipoxin A4 generation: detection by a novel lipoxin A4-ELISA." Lipids 28(12): 1047-53.
Lipoxin A4 (LXA4) possesses potent bioactions. To facilitate its detection, an enzyme-linked immunosorbent assay (ELISA) was developed that proved sensitive and selective. Quantitation by ELISA of LXA4 generated from cellular sources strongly correlated (r = 0.99) with values obtained by high-pressure liquid chromatography (HPLC). We used this LXA4-ELISA to examine parameters influencing LXA4 generation from endogenous substrates during human platelet-neutrophil (PLT-PMN) interactions in vitro. Agonist-induced LXA4 production was clearly evident at a PLT-PMN ratio of 10:1, and recombinant human granulocyte/monocyte colony stimulating factor-priming of PMN augmented LXA4 generation 5-6 fold. The chemotactic peptide formylmethionyl-leucyl-phenylalanine, platelet-derived growth factor and arachidonic acid (20:4n-6) each stimulated formation of immunoreactive LXA4 (iLXA4) in these co-incubations. The presence of iLXA4 was also evaluated in vivo in aspirin-sensitive asthmatic patients who, in a randomized, double-blind crossover design, underwent nasal lavage after they each ingested a predetermined threshold dose of aspirin or placebo. Aspirin challenge provoked statistically significant increases in iLXA4 in each patient (P < 0.005). These results validate the use of a solid-phase ELISA for detection of LXA4. Furthermore, the use of this ELISA has allowed the first documentation of iLXA4 formation in human subjects with aspirin-sensitive asthma following specific antigenic challenge.
King, K. A., J. Hua, et al. (1993). "CD10/neutral endopeptidase 24.11 regulates fetal lung growth and maturation in utero by potentiating endogenous bombesin-like peptides." J Clin Invest 91(5): 1969-73.
Bombesin-like peptides (BLPs) are mitogens for bronchial epithelial cells and small cell lung carcinomas, and increase fetal lung growth and maturation in utero and in organ cultures. BLPs are hydrolyzed by the enzyme CD10/neutral endopeptidase 24.11 (CD10/NEP) which is expressed in bronchial epithelium and functions to inhibit BLP-mediated growth of small cell lung carcinomas. To determine whether CD10/NEP regulates peptide-mediated lung development, we administered a specific CD10/NEP inhibitor, SCH32615, to fetal mice in utero from gestational days e15-17. Fetal lung tissues were evaluated on e18 for: (a) growth using [3H]thymidine incorporation into nuclear DNA; and (b) maturation using: [3H]-choline incorporation into surfactant phospholipids, electron microscopy for type II pneumocytes, and Northern blot analyses for surfactant apoproteins A, B, and C. Inhibition of CD10/NEP stimulated [3H]thymidine incorporation into DNA (70% above baseline, P < 0.005), [3H]choline incorporation into surfactant phospholipids (38% above baseline, P < 0.005), increased numbers of type II pneumocytes (36% above baseline, P = 0.07), and fivefold higher surfactant protein A transcripts (P < 0.05). CD10/NEP-mediated effects were completely blocked by the specific bombesin receptor antagonist, [D-Phe12, Leu14]bombesin. These observations suggest that CD10/NEP regulates fetal lung growth and maturation mediated by endogenous BLPs.
Israel, E., A. R. Fischer, et al. (1993). "The pivotal role of 5-lipoxygenase products in the reaction of aspirin-sensitive asthmatics to aspirin." Am Rev Respir Dis 148(6 Pt 1): 1447-51.
A subset of persons with asthma develop bronchospasm, naso-ocular, gastrointestinal, and/or dermal reactions after ingesting aspirin (ASA) or agents with the capacity to inhibit cyclooxygenase. The bronchopulmonary reactions have been associated with a rise in urinary LTE4. We examined the effects of an inhibitor of 5-lipoxygenase, zileuton, in a group of eight asthmatic patients with known sensitivity to ASA accompanied by LTE4 hyperexcretion. We first confirmed ASA sensitivity and an increase in urinary LTE4 after ASA ingestion in these patients using a placebo-controlled ASA challenge. Subjects were then randomized to a double-blind, crossover trial to examine the effects of zileuton versus placebo on the response to ASA. Zileuton treatment decreased baseline urinary LTE4 excretion from a mean of 469 +/- 141 pg/mg creatinine to 137 +/- 69 pg/mg creatinine (p < 0.02) and blunted the maximum increase in urinary LTE4 after ingestion of ASA (3,539 +/- 826 pg/mg creatinine versus 1,120 +/- 316 pg/mg creatinine [p < 0.01]). The pre-ASA challenge FEV1 was unchanged by zileuton (3.41 +/- 0.15 L versus 3.35 +/- 0.17 L, zileuton versus placebo). Zileuton prevented the fall in FEV1 in response to ingestion of ASA; post-ASA ingestion the mean of the minimal FEV1 fell to 2.72 +/- 0.18 L on the placebo day while there was no significant fall on the zileuton day (3.26 +/- 0.17 L; p < 0.014). Zileuton also prevented the development of the nasal, gastrointestinal (p < 0.006 and p < 0.025, respectively), and dermal symptoms which developed after ASA ingestion.(ABSTRACT TRUNCATED AT 250 WORDS)
Gavriely, N., J. Solway, et al. (1993). "Construction and uses of a concentric catheter for gas sampling in lung airways." J Appl Physiol 74(6): 3063-7.
A catheter for intra-airway sampling of gas concentrations was constructed from concentric polyethylene tubes. The internal tube (0.58 mm ID, 0.91 mm OD) was connected to a gas analyzer while the external tube (1.20 mm ID, 1.75 mm OD) was constantly flushed by air or a calibration gas, except during sampling. Injection and sampling dead spaces were 0.35 and 0.28 ml, respectively. Delay at 4-ml/min sampling rate was 4.0 +/- 0.2 s. The 0-90% step response to a sudden change in gas composition was 0.24 s when connected to a mass spectrometer. This catheter was used to assess tracer gas dispersion during oscillatory flow (1-20 Hz) in a straight long tube. Local concentrations measured through the catheter, after a small bolus of tracer gas was injected through the external tube, compared favorably with direct measurements through needles inserted via the tube wall and with theoretical predictions. The catheter was also used to measure intra-airway gas concentrations in dog airways during spontaneous breathing, conventional mechanical ventilation, high-frequency ventilation, high-frequency vibration ventilation, and constant-flow ventilation. It ws placed by a fiber-optic bronchoscope and used to measure local quasi-steady concentrations of CO2 and local dispersion with the bolus method. The occurrence of catheter clogging with secretions was substantially reduced with flow through the external tube. Transmitting a calibration gas through the external tube facilitated in situ recalibration of the gas analyzer without removing the catheter. The use of this catheter improved the efficiency and accuracy of measurements of gas concentrations inside lung airways.
Gaston, B., J. Reilly, et al. (1993). "Endogenous nitrogen oxides and bronchodilator S-nitrosothiols in human airways." Proc Natl Acad Sci U S A 90(23): 10957-61.
Recent discoveries suggesting essential bioactivities of nitric oxide (NO.) in the lung are difficult to reconcile with the established pulmonary cytotoxicity of this common air pollutant. These conflicting observations suggest that metabolic intermediaries may exist in the lung to modulate the bioactivity and toxicity of NO.. We report that S-nitrosothiols (RS-NO), predominantly the adduct with glutathione, are present at nano- to micromolar concentrations in the airways of normal subjects and that their levels vary in different human pathophysiologic states. These endogenous RS-NO are long-lived, potent relaxants of human airways under physiological O2 concentrations. Moreover, RS-NO form in high concentrations upon administration of NO. gas. Nitrite (10-20 microM) is found in airway lining fluid in concentrations linearly proportional to leukocyte counts, suggestive of local NO. metabolism. NO. itself was not detected either free in solution or in complexes with transition metals. These observations may provide insight into the means by which NO. is packaged in biological systems to preserve its bioactivity and limit its potential O2-dependent toxicity and suggest an important role for NO. in regulation of airway luminal homeostasis.
Shore, S. A., M. A. Martins, et al. (1992). "Effect of the NEP inhibitor SCH32615 on airway responses to intravenous substance P in guinea pigs." J Appl Physiol 73(5): 1847-53.
We examined the effects of the selective neutral endopeptidase (NEP) inhibitor SCH32615 on airway responses to rapid intravenous infusions of substance P (SP) and neurokinin A (NKA) and on recovery of administered tachykinins from arterial blood in anesthetized mechanically ventilated guinea pigs. SCH32615, in doses that cause a marked increase in the magnitude of bronchoconstriction induced by infused NKA, had little effect on the changes in pulmonary conductance (GL) or dynamic compliance induced by SP. In animals in which SCH32615 (1 mg/kg) was administered in combination with the angiotensin-converting enzyme (ACE) inhibitor captopril (5.7 mg/kg), the dose of SP required to decrease GL by 50% was fourfold less than in animals that received captopril alone (P < 0.005). SP measured in arterial blood withdrawn within 45 s of intravenous administration of this tachykinin was not different in control and SCH32615-treated animals, whereas captopril caused an approximately threefold increase in SP concentrations (P < 0.005). When SCH32615 and captopril were administered together, significantly more SP was recovered than when captopril or SCH32615 was administered alone (P < 0.0005). Our results are consistent with the hypothesis that both NEP and ACE contribute to the degradation of intravenously infused SP. ACE degradation of SP is sufficient to limit SP-induced bronchoconstriction even in the presence of specific NEP inhibition.
O'Donnell, W. J., M. Rosenberg, et al. (1992). "Acetazolamide and furosemide attenuate asthma induced by hyperventilation of cold, dry air." Am Rev Respir Dis 146(6): 1518-23.
We investigated the assumption that the efficacy of inhaled diuretics in asthma is dependent upon inhibition of the Na+/K+/2Cl- cotransporter. We compared the protective effect of acetazolamide, a diuretic without significant effect on the loop cotransporter, with the protection provided by inhaled furosemide in a cold, dry air hyperventilation model of asthma. Seven asthmatic subjects underwent a baseline bronchial challenge and then received a nebulized dose of 80 mg of furosemide or 500 mg of acetazolamide or saline placebo in a randomized, double-blind, placebo-controlled crossover design. Repeat challenges were performed immediately and at 2 and 4 h postnebulization. Acetazolamide caused a 47.2% increase in the amount of cold, dry air required to reduce the FEV1, by 20% (expressed in terms of respiratory heat loss as PD20RHL), from 0.79 multiplied or divided by (x/divided by) 1.13 kcal/min (geometric mean x/divided by geometric SEM) at baseline to 1.17 x/divided by 1.09 kcal/min postnebulization (p < 0.025). Furosemide increased the geometric mean PD20RHL by 53.9%, from 0.86 x/divided by 1.12 kcal/min to 1.33 x/divided by 1.12 kcal/min (p < 0.001). There was no significant change after placebo inhalation (0.81 x/divided by 1.15 kcal/min versus 0.87 x/divided by 1.10 kcal/min, NS). Airway responsiveness had returned to baseline by 2 h postnebulization on all 3 days. Furosemide also caused bronchodilatation, producing a 14.1% rise in the mean FEV1 (p < 0.005 versus prenebulization), whereas neither acetazolamide nor placebo altered airway tone significantly.(ABSTRACT TRUNCATED AT 250 WORDS)
Molfino, N. A., A. S. Slutsky, et al. (1992). "Changes in cross-sectional airway areas induced by methacholine, histamine, and LTC4 in asthmatic subjects." Am Rev Respir Dis 146(3): 577-80.
To examine whether leukotrienes, histamine, and methacholine have different sites of bronchoconstrictor action, we studied 8 stable asthmatic subjects (mean age +/- SD, 26 +/- 5 yr) on 3 different days. On each day, a randomized challenge with LTC4, methacholine, or histamine was performed until the dose that provoked a fall of 20% in FEV1 (PC20) was obtained. Complete and partial flow-volume curves as well as area-distance profiles generated by the acoustic reflection technique (ART) at a fixed lung volume were obtained in all subjects before and after each inhalation challenge. No significant differences were found in pulmonary function or baseline cross-sectional airway areas for the different study days. The three agonists provoked significant (p less than 0.05) bronchoconstriction at the level of the main bronchi when identical falls of FEV1 were achieved. Similarly, equal reductions of V30p were elicited by the three agonists. However, LTC4 and methacholine induced additional tracheal constriction but histamine inhalation did not. These differences in the degree of tracheal constriction were statistically significant (p less than 0.05; ANOVA). These results may be explained by distinct pharmacologic properties of the agents used and may have relevance in the understanding of the pathophysiology of asthma.
Kamm, R. D. and J. M. Drazen (1992). "Airway hyperresponsiveness and airway wall thickening in asthma. A quantitative approach." Am Rev Respir Dis 145(6): 1249-50.
Iijima, H., N. P. Gerard, et al. (1992). "Exon 16 del: a novel form of human neutral endopeptidase (CALLA)." Am J Physiol 262(6 Pt 1): L725-9.
The enzyme neutral metalloendopeptidase (E.C. 184.108.40.206), also known as the common acute lymphocytic leukemia antigen, neutral endopeptidase, or enkephalinase, functions as an inactivator of a wide variety of signaling oligopeptides such as substance P, neurokinin A, enkephalins, endothelin, atrial natriuretic factor, and formyl chemotactic peptides. A cDNA clone isolated from a human lung library encodes a fragment of neutral metalloendopeptidase containing an internal 81 base pair deletion when compared with the human placental cDNA for this enzyme. Comparison of the deleted cDNA sequence with the intron-exon structure recently determined as the common acute lymphocytic leukemia antigen reveals that the 81 base pairs corresponds precisely with exon 16. RNA analysis using splice junction oligonucleotides indicates that the 16 del form constitutes a minor but significant fraction of the RNA species present in human lung. Expression of constructs containing "wild type" and "exon 16 del" neutral endopeptidases in COS-7 cells reveals that deletion of this 27 amino acid segment reduces enzymatic activity toward the synthetic substrate glutaryl-alanyl-alanyl-phenyl-alanyl-4-methoxy-2-naphthylamide to barely detectable levels.
Dupuy, P. M., S. A. Shore, et al. (1992). "Bronchodilator action of inhaled nitric oxide in guinea pigs." J Clin Invest 90(2): 421-8.
The effects of inhaling nitric oxide (NO) on airway mechanics were studied in anesthetized and mechanically ventilated guinea pigs. In animals without induced bronchoconstriction, breathing 300 ppm NO decreased baseline pulmonary resistance (RL) from 0.138 +/- 0.004 (mean +/- SE) to 0.125 +/- 0.002 cmH2O/ml.s (P less than 0.05). When an intravenous infusion of methacholine (3.5-12 micrograms/kg.min) was used to increase RL from 0.143 +/- 0.008 to 0.474 +/- 0.041 cmH2O/ml.s (P less than 0.05), inhalation of 5-300 ppm NO-containing gas mixtures produced a dose-related, rapid, consistent, and reversible reduction of RL and an increase of dynamic lung compliance. The onset of bronchodilation was rapid, beginning within 30 s after commencing inhalation. An inhaled NO concentration of 15.0 +/- 2.1 ppm was required to reduce RL by 50% of the induced bronchoconstriction. Inhalation of 100 ppm NO for 1 h did not produce tolerance to its bronchodilator effect nor did it induce substantial methemoglobinemia (less than 2%). The bronchodilating effects of NO were additive with the effects of inhaled terbutaline, irrespective of the sequence of NO and terbutaline administration. Inhaling aerosol generated from S-nitroso-N-acetylpenicillamine also induced a rapid and profound decrease of RL from 0.453 +/- 0.022 to 0.287 +/- 0.022 cmH2O/ml.s, which lasted for over 15 min in guinea pigs broncho-constricted with methacholine. Our results indicate that low levels of inhaled gaseous NO, or an aerosolized NO-releasing compound are potent bronchodilators in guinea pigs.
Drazen, J. M., J. O'Brien, et al. (1992). "Recovery of leukotriene E4 from the urine of patients with airway obstruction." Am Rev Respir Dis 146(1): 104-8.
The urinary excretion of leukotriene E4 (LTE4) was measured in subjects presenting for emergency treatment of airway obstruction. A total of 72 subjects presenting with airway obstruction performed peak flow determinations before and after three treatments with nebulized albuterol given at 20-min intervals. Of these subjects, 22 more than doubled their peak flow rates, while 19 failed to increase their peak flow rates more than 25% during the treatment period. These groups were designated "responders" and "nonresponders," respectively. Urinary LTE4 excretion was determined in 16 of the 22 responders and 12 of the 19 nonresponders as well as 13 normal subjects by precolumn extraction, analytic reversed-phase high-performance liquid chromatography, and enzyme immunoassay. In the normal subjects the urinary LTE4 excretion was significantly (p less than 0.0001) less than the urinary LTE4 measured in the responder subjects, but not less than the urinary LTE4 excretion in the nonresponder group (p = 0.071). The enhanced recovery of LTE4 from the urine of subjects with acutely reversible airway narrowing is consistent with a bronchoconstrictor role for the cysteinyl leukotrienes in spontaneous acute asthma.
Yager, D., M. A. Martins, et al. (1991). "Role of capsaicin-sensitive neurons in histamine-induced luminal liquid in small airways." Clin Exp Allergy 21 Suppl 1: 37-41.
Yager, D., S. Shore, et al. (1991). "Airway luminal liquid. Sources and role as an amplifier of bronchoconstriction." Am Rev Respir Dis 143(3 Pt 2): S52-4.
The release of mediators from inflammatory cells into the airway lumen can initiate a series of events leading to airway obstruction, particularly smooth muscle contraction and alteration of endothelial and epithelial permeability leading to mucosal edema and subsequent influx of liquid into the airway lumen. In this report we briefly review the effects of several inflammatory mediators, including eicosanoids, platelet-activating factor, and histamine, as well as the effects of plasma proteins and tachykinins that may be secondarily released because of the presence of inflammatory mediators on endothelial and epithelial permeability. We then consider physical mechanisms whereby the resulting airway luminal liquid could amplify the response of an airway previously constricted because of smooth muscle contraction. Specifically, liquid in the interstices between epithelial projections that are formed during muscular contraction could amplify the degree of luminal compromise by (1) further decreasing luminal cross-sectional area by occupying space, and (2) providing an additional source of inward recoil because of the surface tension of the air-liquid interface.
Wetmore, L. A., N. P. Gerard, et al. (1991). "Leukotriene receptor on U-937 cells: discriminatory responses to leukotrienes C4 and D4." Am J Physiol 261(2 Pt 1): L164-71.
Dimethyl sulfoxide (DMSO)-differentiated U-937 cells develop cell surface receptors for leukotrienes that, when stimulated, initiate a transient increase in intracellular calcium concentration [( Ca2+]i). We investigated the calcium transient that occurs after addition of leukotriene C4 (LTC4) to determine whether it occurs due to 1) the bioconversion of LTC4 to leukotriene D4 (LTD4), which then acts at the LTD4 receptor; 2) the direct action of LTC4 at the LTD4 receptor; or 3) the action of LTC4 at a receptor selective for LTC4. Bioconversion of [3H]LTC4 to [3H]LTD4 was inhibited by 98% when DMSO-differentiated U-937 cells were incubated with 10 mM AT-125 compared with control cells. The dose-response curve for LTC4, with [Ca2+]i as the index of response, was parallel to that for LTD4 but was significantly (P less than 0.0001) shifted 1.6 +/- 0.11 log units to the right. AT-125 did not change the response to LTD4 but the LTC4 dose-response curve was shifted on additional 1.7 logo units to the right. The antagonists SKF 104353 (1 microM) and LY 171883 (10 microM) shifted the dose-response curve for LTD4 3.0 +/- 0.23 and 2.5 +/- 0.23 log units, respectively, to the right and completely inhibited the change in [Ca2+]i due to LTC4 in the presence of 10 mM AT-125. Molecular modeling studies demonstrated a striking difference in the spatial configuration of LTC4 and LTD4, likely accounting for the ability of cell surface receptors to discriminate between the effects of these two molecules.(ABSTRACT TRUNCATED AT 250 WORDS)
Shore, S. A. and J. M. Drazen (1991). "Relative bronchoconstrictor activity of neurokinin A and neurokinin A fragments in guinea pigs." J Appl Physiol 71(2): 452-7.
We examined the effect of rapid intravenous infusion of neurokinin A (NKA) and selected COOH-terminal NKA fragments on pulmonary conductance (GL) and dynamic compliance in anesthetized mechanically ventilated guinea pigs. The rank order of the dose of peptide required to reduce GL by 50% (ED50GL) was NKA = NKA2-10 = NKA3-10 = NKA4-10 less than NKA5-10 much less than NKA6-10. The time course of bronchoconstriction induced by NKA2-10, NKA3-10, and NKA4-10 was similar to that induced by NKA, whereas NKA5-10 and NKA6-10 each had a shorter duration of action than NKA for a similar induced maximal change in GL. To determine whether degradation of these NKA fragments by neutral endopeptidase (NEP) modulates their bronchoconstrictor activity as it does for native NKA, we examined the effect of the NEP inhibitor SCH32615 on NKA3-10-, NKA5-10-, and NKA6-10-induced changes in GL. We have previously reported that the ED50GL for NKA was approximately 20-fold lower in animals pretreated with SCH32615 (1 mg/kg) than in control guinea pigs. SCH32615 caused a 16-fold decrease in ED50GL for NKA3-10 (P less than 0.001) but had no effect on airway responses to NKA5-10 or NKA6-10. The results demonstrate that the magnitude and duration of bronchoconstriction induced by potential aminopeptidase degradation products of NKA are similar to those of the native peptide. Aminopeptidases do not, therefore, have the capacity to modulate the bronchoconstriction induced by this peptide.(ABSTRACT TRUNCATED AT 250 WORDS)
Martins, M. A., S. A. Shore, et al. (1991). "Peptidase modulation of the pulmonary effects of tachykinins." Int Arch Allergy Appl Immunol 94(1-4): 325-9.
The physiological effects of the tachykinin peptides substance P (SP) and neurokinin A (NKA) are limited by their microenvironmental degradation. We used the isolated tracheally superfused guinea pig lung to examine the importance of various degradative enzymes in limiting the physiological effects of exogenously administered and endogenously released tachykinins. When SP and NKA are administered via the airway epithelium, neutral endopeptidase (NEP; EC 220.127.116.11) is the major degradative enzyme as indicated by the effects of NEP inhibitors alone compared to the effects of a NEP inhibitor along with a cocktail of other peptidase inhibitors. The effects of enzyme inhibitors on physiological responses is mirrored in the amounts of peptide recovered from lung perfusates as determined using an enzyme-linked immunosorbent assay. We found similar effects when SP and NKA were released endogenously by the acute infusion of capsaicin. These data indicate that NEP is the predominant degradative enzyme modulating the effects of SP and NKA administered via the airways.
Martins, M. A., S. A. Shore, et al. (1991). "Tachykinin recovery during postmortem bronchoconstriction in guinea pig lungs." J Appl Physiol 70(3): 1215-9.
We examined the role of substance P (SP) and neurokinin A (NKA) in the postmortem bronchoconstriction in guinea pig lungs using isolated lungs superfused via the trachea. Airway opening pressure (Pao) during superfusion was monitored and the superfusate collected for analysis of SP- and NKA-like immunoreactivities (SP-LI and NKA-LI, respectively). Peak Pao (39.0 +/- 3.9 cmH2O) was reached 10 min after starting superfusion; Pao decreased slowly thereafter, reaching only 9.9 +/- 2.2% of the peak value 2 h after starting superfusion (P less than 0.005); 12.6 +/- 2.6 and 34.0 +/- 9.7 fmol of SP-LI and NKA-LI, respectively, were found in the fraction corresponding to 10-20 min of superfusion. Recovered immunoreactivities decreased to 5.2 +/- 0.3 and 9.3 +/- 1.8 fmol of SP-LI and NKA-LI, respectively, in the fraction corresponding to 110-120 min of superfusion (P less than 0.05). Inhibition of neutral endopeptidase with thiorphan resulted in significantly greater increases in Pao (P less than 0.005) and augmentation of the recovery of SP-LI and NKA-LI (P less than 0.05 and P less than 0.001, respectively). Capsaicin treatment of animals 7-10 days before the removal of their lungs abolished the increase in Pao during superfusion and resulted in a significant decrease in the amount of SP-LI and NKA-LI recovered. Our data confirm that tachykinin release occurs during postmortem bronchoconstriction in guinea pig lungs and, furthermore, that tachykinin degradation by NEP modulates the intensity of this response.
Martins, M. A., S. A. Shore, et al. (1991). "Capsaicin-induced release of tachykinins: effects of enzyme inhibitors." J Appl Physiol 70(5): 1950-6.
We studied the effects of neutral endopeptidase (NEP) and angiotensin-converting enzyme (ACE) inhibition on the airway responses and the recovery of endogenously released substance P- and neurokinin A-like immunoreactivities (SP-LI and NKA-LI) after tracheal injection of capsaicin in isolated guinea pig lungs superfused through the trachea. Capsaicin in doses from 10(-10) to 10(-7) mol induced a dose-dependent increase in airway opening pressure and release of SP-LI and NKA-LI. Airway opening pressure changes and the recovery of SP-LI and NKA-LI were significantly greater in lungs superfused with the NEP inhibitor SCH 32615 than in control lungs. ACE inhibition with captopril did not increase the mechanical response or the recovery of SP-LI compared with lungs not receiving captopril. In lungs from guinea pigs pretreated with high doses of capsaicin 7-10 days before study, a regimen designed to deplete endogenous tachykinins, there was a significant decrease in the content and release of NKA-LI and SP-LI. There were no detectable airway effects of acute capsaicin infusion even after doses of 10(-5) mol. Because NEP is important in modulating the airway effects of endogenously released tachykinins after tracheal infusion of capsaicin, but ACE is not, it seems likely that tracheal administration of capsaicin releases tachykinins from epithelial rather than endothelial loci.
Martins, M. A., S. A. Shore, et al. (1991). "Release of tachykinins by histamine, methacholine, PAF, LTD4, and substance P from guinea pig lungs." Am J Physiol 261(6 Pt 1): L449-55.
The release of substance P- and neurokinin A-like immunoreactivities (SP-LI and NKA-LI) after tracheal infusion of histamine, methacholine, leukotriene D4, and platelet-activating factor was measured in isolated guinea pig lungs superfused through the trachea. Infusion of each of these agonists was associated with a significant (P less than 0.05) increase in the recovery of both SP-LI and NKA-LI from lung perfusates compared with preinfusion baseline recoveries of these peptides. After infusion of bronchoactive mediators, approximately 4-15 times more NKA-LI than SP-LI was recovered from the lung superfusate. Coincident with the release of neuropeptides, mediator infusion was accompanied by an increase in airway opening pressure (Pao). Addition to the perfusate of the neutral endopeptidase inhibitor thiorphan, 1 microM increased the change in Pao induced by histamine (10(-8) mol, P less than 0.005) and methacholine (10(-8) mol, P less than 0.02) and increased the recovery of NKA-LI (P less than 0.05 for histamine and methacholine). Addition of isoproterenol to the perfusion buffer reduced, but did not abolish, either the Pao response or the increased recovery of NKA-LI (P less than 0.05) observed after histamine infusion. We conclude that bronchoactive agonists have the capacity to release both SP-LI and NKA-LI, and we speculate that NKA contributes to the bronchomotor response observed in response to histamine or methacholine.
Drazen, J. M. and E. Israel (1991). "Asthma: a solution to half the puzzle?" Am Rev Respir Dis 144(4): 743-4.
Wanner, A., W. M. Abraham, et al. (1990). "NHLBI Workshop Summary. Models of airway hyperresponsiveness." Am Rev Respir Dis 141(1): 253-7.
Martins, M. A., S. A. Shore, et al. (1990). "Peptidase modulation of the pulmonary effects of tachykinins in tracheal superfused guinea pig lungs." J Clin Invest 85(1): 170-6.
The effects of the angiotensin converting enzyme (ACE) inhibitor captopril and the neutral endopeptidase (NEP) inhibitors thiorphan and SCH 32615 on the changes in airway opening pressure (PaO) and the recovery of offered peptide were studied after intratracheal administration of substance P (SP) and neurokinin A (NKA) in isolated guinea pig lungs superfused through the trachea. Pao changes and the recovery of offered peptide were significantly greater in NEP inhibitor-treated lungs than in control lungs. Captopril did not cause a significant change in the physiological effects or the recovery of SP and NKA. HPLC analysis of [3H]Pro2,4-SP and 125I-Histidyl1-NKA perfused through the airways showed major cleavage products consistent with NEP action. We conclude that there is significant degradation of both SP and NKA after tracheal infusion of peptides by NEP-like but not by ACE activity; this effect significantly influences the physiological effects of these peptides.
Koshino, T., K. R. Bhaskar, et al. (1990). "Recovery of an epitope recognized by a novel monoclonal antibody from airway lavage during experimental induction of chronic bronchitis." Am J Respir Cell Mol Biol 2(5): 453-62.
Prolonged exposure of dogs to high concentrations of SO2 gas results in a syndrome with many of the characteristics of human chronic bronchitis, including cough and chronic mucous hypersecretion as well as airway obstruction. We developed and used a novel monoclonal antibody, GB-4B, raised against epithelial glycoprotein isolated from human hypersecretory mucus to probe airway lavage samples from dogs before and during prolonged exposure to SO2 gas. There were relatively low mean titers of the epitope recognized by GB-4B in airway lavage fluid as evidenced by enzyme-linked immunosorbent assay before exposure to SO2 gas. After 25 to 50 wk of SO2 exposure, the dogs showed a significant increase in pulmonary resistance and there was a significant increase in the titer of the epitope in the airway lavage fluid. Using the same antibody immunohistochemical analysis of airway tissues from SO2-exposed dogs revealed patchy staining of the mucous glands and airway secretory cells and dense staining along the airway surface; airway tissue from control dogs and one SO2-exposed dog whose lavage fluid did not contain the epitope showed little or no staining. These data demonstrate that similar mucin epitopes appear in airway lavage fluid under hypersecretory conditions in both animals and humans. The epitope may have utility as a marker of chronic mucous hypersecretion.
Israel, E., R. Dermarkarian, et al. (1990). "The effects of a 5-lipoxygenase inhibitor on asthma induced by cold, dry air." N Engl J Med 323(25): 1740-4.
BACKGROUND. The enzyme 5-lipoxygenase catalyzes the metabolism of arachidonic acid to form products that have been implicated in the airway obstruction of asthma. We hypothesized that if products of the 5-lipoxygenase pathway are important in mediating this obstruction, then prevention of their formation should decrease the severity of an induced asthmatic response. METHODS. In a randomized, double-blind, placebo-controlled, crossover study, we examined the effect of A-64077, a 5-lipoxygenase inhibitor, on the bronchoconstriction induced by hyperventilation of cold, dry air in 13 patients with asthma. The completeness of 5-lipoxygenase inhibition was confirmed by examining the profile of eicosanoids produced in whole blood ex vivo after activation with the calcium ionophore A-23187. RESULTS. A-64077 decreased the mean (+/- SEM) ionophore-induced synthesis of leukotriene B4, a 5-lipoxygenase product, by 74 percent (from 265.3 +/- 30.3 to 69.5 +/- 21.5 ng per milliliter, P less than 0.001), but it did not affect the ionophore-induced synthesis of thromboxane B2, a cyclooxygenase metabolite of arachidonic acid (80.0 +/- 17.1 ng per milliliter before A-64077 vs. 75.8 +/- 14.3 ng per milliliter after A-64077). In concert with the selective inhibition of 5-lipoxygenase by A-64077, the amount of cold, dry air (expressed as respiratory heat exchange) required to reduce the forced expiratory volume in one second by 10 percent was increased by 47 percent after A-64077 (3.0 kJ per minute for placebo vs. 4.4 kJ per minute for A-64077, P less than 0.002). Similar results were obtained when minute ventilation was used as an indicator of outcome (27.5 liters per minute for placebo vs. 39.8 liters per minute for A-64077, P less than 0.005). CONCLUSIONS. Selective inhibition of 5-lipoxygenase by A-64077 is associated with a significant amelioration of the asthmatic response to cold, dry air, suggesting that 5-lipoxygenase products are involved in this response. This approach may be useful in the treatment of asthma.
Ingenito, E. P., B. M. Pichurko, et al. (1990). "Breathing pattern affects respiratory heat loss but not bronchoconstrictor response in asthma." Lung 168(1): 23-34.
To determine whether changes in breathing pattern alone affect respiratory heat loss (RHL) and the constrictor response to cold dry gas hyperpnea in asthmatic subjects, we performed the following 2 part study: first we measured RHL in 8 asthmatic and 8 normal subjects during controlled eucapnic hyperpnea while they breathed at inspiratory to expiratory ratios (I/E) of 1:3, 3:1, and 2:2, and we recorded postchallenge forced expiratory volume in 1 sec (FEV1) in the asthmatic group; we then performed the same measurements in 8 asthmatic and 8 normal subjects at fixed target minute ventilation (VE) for tidal volumes of 0.2 X Forced vital capacity (FVC), 0.4 X FVC, and 0.6 X FVC by varying the target respiratory rate appropriately. Our results show that (1) increasing I/E ratio or tidal volume-frequency ratio (VT/f) at fixed VE produced small but statistically significant increases (p less than 0.05) in overall heat loss per unit volume of respired gas (RHL/VE) in both asthmatic and nonasthmatic subjects of 1-4 cal/L; (2) changes in breathing pattern alone did not affect bronchoconstrictor response as assessed by lack of change in slopes and intercepts of % delta FEV1 vs. RHL dose-response curves; and (3) the increase in RHL per unit volume of respired gas resulting from increasing VT/f ratios during cold gas hyperpnea was significantly greater in asthmatic than in nonasthmatic subjects. We conclude that changes in breathing pattern may affect overall RHL measured at the mouth, although the maximum effect of such changes in both asthmatic and nonasthmatic subjects is small (10-15%); that such changes do not significantly alter airway constrictor response in asthmatic persons; and (3) that the effects of changing breathing pattern on RHL may be more pronounced in asthmatic than nonasthmatic subjects, which suggests that the asthmatic group may be less able to adapt to factors that alter the magnitude and site of RHL.
Yager, D., J. P. Butler, et al. (1989). "Amplification of airway constriction due to liquid filling of airway interstices." J Appl Physiol 66(6): 2873-84.
Luminal epithelial projections formed during bronchoconstriction define interstices in which liquid can collect. Liquid in these interstices could amplify the degree of luminal compromise due to muscular contraction in at least two distinct ways. First, the luminal cross-sectional area is reduced by simple filling of the interstices. Second, if the surface tension (gamma) of the air-liquid interface is positive, the pressure drop across the interface produces an additional inward force that can further constrict the airway. We present a theoretical treatment of these two mechanisms together with data which suggest that both may significantly amplify the luminal narrowing due to airway smooth muscle contraction, particularly in small airways when gamma is high. To qualitatively assess the effects of altered gamma, guinea pig lungs with normal and altered airway liquid lining layers were frozen and studied while fully hydrated by low-temperature scanning electron microscopy. Airway gamma was altered in these animals by intratracheal instillation of 0.5 mg lysoplatelet-activating factor (lyso-PAF). The interstices of normal airways were dry, whereas the interstices of airways with altered surface lining layers were liquid filled. In addition, the surfactant inhibitory properties of lyso-PAF, 2-arachidonyl-PAF, and dipalmitoyl phosphatidylcholine (DPPC) were measured with a pulsating bubble surfactometer, using surfactant TA as the model surfactant. Minimal gamma (gamma min) of surfactant TA alone was 4.0 +/- 0.2 dyn/cm; a 5% mixture of lyso-PAF with surfactant TA resulted in a significantly (P less than 0.02) greater gamma min of 8.8 +/- 1.8 dyn/cm. In contrast, 2-arachidonyl-PAF and DPPC had minimal effects on gamma min of surfactant TA.
Shore, S. A. and J. M. Drazen (1989). "Enhanced airway responses to substance P after repeated challenge in guinea pigs." J Appl Physiol 66(2): 955-61.
We performed three consecutive dose-response curves to rapid intravenous infusions of substance P (SP) in anesthetized, mechanically ventilated guinea pigs. The dose of SP required to decrease pulmonary conductance to 50% of its base-line value (ED50GL) decreased 2.8-fold (P less than 0.002) and 3.3-fold (P less than 0.001) on the second and third dose-response curves, respectively, compared with the first. SP did not alter airway responses to intravenous histamine but did cause a significant (3.7-fold) decrease in ED50GL for dose-response curves to intravenous capsaicin, an agent that causes bronchoconstriction by release of endogenous tachykinins. The neutral metalloendopeptidase inhibitor thiorphan (0.5 mg) and the angiotensin-converting enzyme inhibitor captopril (1.7 mg) both caused a marked enhancement of airway responses to SP observed on the first dose-response curve but did not alter the enhancement of SP-induced airway responses produced by repeated SP challenge. The anticholinergic atropine (5 mg/kg iv), the antihistamine mepyramine (8 mg/kg iv), and the cyclooxygenase inhibitor indomethacin (30 mg/kg ip) had no effect on the first SP dose-response curve. Atropine and mepyramine did not prevent the enhancement of SP responses observed with repeated challenge, but after pretreatment with either indomethacin or acetylsalicylic acid, dose-response curves to SP were reproducible. Our results indicate that airway responses to intravenous SP are enhanced with repeated SP challenge and suggest that cyclooxygenase products of arachidonic acid metabolism are involved in the mediation of this phenomenon.
Shore, S. A. and J. M. Drazen (1989). "Degradative enzymes modulate airway responses to intravenous neurokinins A and B." J Appl Physiol 67(6): 2504-11.
We studied the effects of the neutral endopeptidase (NEP) inhibitor thiorphan (1.7 mg/kg iv) and the angiotensin-converting enzyme (ACE) inhibitor captopril (5.7 mg/kg iv) on airway responses to rapid intravenous infusions of neurokinin A (NKA) and neurokinin B (NKB) in anesthetized, mechanically ventilated guinea pigs. The dose of NKA required to decrease pulmonary conductance to 50% of its base-line value (ED50GL) was fivefold less (P less than 0.0001) in animals treated with thiorphan compared with controls. NKA1-8, a product resulting from cleavage of NKA by NEP, had no bronchoconstrictor activity. Similar results were obtained by using NKB as the bronchoconstricting agent. Captopril had no significant effect on airway responses to NKA or NKB. In contrast, both thiorphan and captopril decrease the ED50GL for substance P (SP). We also compared the relative bronchoconstrictor potency of NKA, NKB, and SP. In control animals, the rank order of ED50GL values was NKA much less than NKB = SP. NKA also caused a more prolonged bronchoconstriction than SP or NKB. Thiorphan had no effect on the rank order of bronchoconstrictor potency, but in animals treated with captopril, the rank order of ED50GL values was altered to NKA less than SP less than NKB. These results suggest that degradation of NKA and NKB by NEP but not by ACE is an important determinant of the bronchoconstriction induced by these peptides. The degradation by ACE of SP but not NKA or NKB influences the observed relative potency of the three tachykinins as bronchoactive agents.
Ray, D. W., C. Hernandez, et al. (1989). "Tachykinins mediate bronchoconstriction elicited by isocapnic hyperpnea in guinea pigs." J Appl Physiol 66(3): 1108-12.
We tested the hypothesis that tachykinins mediate hyperpnea-induced bronchoconstriction (HIB) in 28 guinea pigs. Stimulus-response curves to increasing minute ventilation with dry gas were generated in animals depleted of tachykinins by capsaicin pretreatment and in animals pretreated with phosphoramidon, a neutral metalloendopeptidase inhibitor. Sixteen anesthetized guinea pigs received capsaicin (50 mg/kg sc) after aminophylline (10 mg/kg ip) and terbutaline (0.1 mg/kg sc). An additional 12 animals received saline (1 ml sc) instead of capsaicin. One week later, all animals were anesthetized, given propranolol (1 mg/kg iv), and mechanically ventilated (6 ml/kg, 60 breaths/min, 50% O2 in air fully water saturated). Phosphoramidon (0.5 mg iv) was administered to five of the noncapsaicin-treated guinea pigs. Eucapnic dry gas (95% O2-5% CO2) hyperpnea "challenges" were performed by increasing the tidal volume (2-6 ml) and frequency (150 breaths/min) for 5 min. Capsaicin-pretreated animals showed marked attenuation in HIB, with a rightward shift of the stimulus-response curve compared with controls; the estimated tidal volume required to elicit a twofold increase in respiratory system resistance (ES200) was 5.0 ml for capsaicin-pretreated animals vs. 3.7 ml for controls (P less than 0.03). Phosphoramidon-treated animals were more reactive to dry gas hyperpnea compared with control (ES200 = 2.6 ml; P less than 0.0001). Methacholine dose-response curves (10(-11) to 10(-7) mol iv) obtained at the conclusion of the experiments were similar among capsaicin, phosphoramidon, and control groups. These findings implicate tachykinin release as an important mechanism of HIB in guinea pigs.
Pichurko, B. M., R. H. Ingram, Jr., et al. (1989). "Localization of the site of the bronchoconstrictor effects of leukotriene C4 compared with that of histamine in asthmatic subjects." Am Rev Respir Dis 140(2): 334-9.
Although the sulfidopeptide leukotrienes are known to be potent bronchoconstrictors, the relative aerodynamic site of response to these compounds is controversial. We determined the decrease in maximal expiratory flow rates (Vmax) from partial and maximal flow-volume curves in seven asthmatic subjects after inhalation of aerosols of histamine or leukotriene C4 (LTC4) while breathing air or a mixture of 80% helium and 20% oxygen (He/O2). Density dependence (DD) of maximal expiratory flow was determined from partial expiratory flow volume curves by an isovolumic comparison of maximal expiratory flows with subjects breathing He/O2 with those obtained while breathing air. Measurements were made before and after inhalation of aerosols generated from graded concentrations of each constrictor agent. An aerodynamic site of response to LTC4 more central than for histamine was indicated by a significant (p less than 0.02) increase in DD with the former but not with the latter agonist. The ratio of Vmax at 30% vital capacity determined from maximal and partial maneuvers (M/P) was routinely higher at baseline while breathing He/O2 compared to the corresponding values with air, suggesting a degree of peripheral obstruction that was reversed by a deep inhalation. Obstruction induced by LTC4 inhalation resulted in a greater increase in M/P compared with baseline when air was the test gas (p less than 0.02). This was not observed when He/O2 was the test gas. Similar effects on M/P were not induced by histamine aerosol inhalation, consistent with a central airway response to LTC4 that was not affected by volume history.(ABSTRACT TRUNCATED AT 250 WORDS)
Martin, T. R., S. J. Galli, et al. (1989). "Role of mast cells in anaphylaxis. Evidence for the importance of mast cells in the cardiopulmonary alterations and death induced by anti-IgE in mice." J Clin Invest 83(4): 1375-83.
We used genetically mast cell-deficient WBB6F1-W/Wv and WCB6F1-S1/S1d mice and the congenic normal (+/+) mice to investigate the effects of intravenous infusion of goat antimouse IgE on heart rate (HR), pulmonary dynamic compliance (Cdyn), pulmonary conductance (GL), and survival. In WBB6F1-+/+ and WCB6F1-+/+ mice, anti-IgE induced extensive degranulation of tracheobronchial mast cells, as well as significant elevation of HR, significant reductions in Cdyn and GL and, in some cases, death. In contrast, W/Wv and S1/S1d mice exhibited little or no pathophysiological responses and no mortality after challenge with anti-IgE. In W/Wv mice reconstituted with mast cells by intravenous administration of bone marrow cells derived from congenic +/+ mice (+/+ BM----W/Wv mice), anti-IgE induced extensive mast cell degranulation, as well as pathophysiological responses and mortality similar to those observed in WBB6F1-+/+ mice. These findings suggest a critical role for mast cells in the development of the cardiopulmonary changes and mortality associated with anti-IgE-induced anaphylaxis.
Ludwig, M. S., S. Bellofiore, et al. (1989). "Dynamics of the collateral pathways of canine lungs after flow interruption." J Appl Physiol 67(3): 1213-9.
After interruption of a constant flow (Vcoll) delivered through a bronchoscope into a wedged segment of lung, the pressure at the tip of the bronchoscope (Pb) often decays in a pattern seemingly indicative of two time constants. We tested the hypothesis that the initial more rapid component of the decay is associated with pressure equilibration across the bronchial resistance (Rb), separating bronchoscope tip from alveolus, and that the slower component is associated with pressure equilibration across the collateral pathways separating the wedged segment from surrounding regions. In eight open-chest mongrel dogs, we affixed an alveolar capsule to the segment subtended by the wedged bronchoscope and measured alveolar pressure (PA) and Pb during delivery of Vcoll into the segment and after its sudden interruption. Under both control conditions and after delivery of aerosolized histamine (1.0 or 10 mg/ml), we were unable to demonstrate a gradient between Pb and PA either during constant flow or after flow interruption. Whenever the decay of Pb was not monoexponential, neither was that of PA. Thus there was no evidence of an appreciable Rb, and the rapid component of the decay must be attributable to other factors. In a second protocol, we examined whether behavior departing from monoexponential decay was attributable to the presence of multicompartment behavior within the wedged segment or rather reflected the behavior of a single homogeneous but nonlinear compartment. In five closed-chest dogs, we systematically varied the initial Pb by changing Vcoll and recorded nonexponential pressure decay after flow interruption.(ABSTRACT TRUNCATED AT 250 WORDS)
Israel, E., E. F. Juniper, et al. (1989). "Effect of a leukotriene antagonist, LY171883, on cold air-induced bronchoconstriction in asthmatics." Am Rev Respir Dis 140(5): 1348-53.
Isocapnic hyperpnea (ISH) of cold air induces bronchoconstriction in many asthmatic subjects. Although this response is well described, it is unclear whether this bronchoconstriction is related to the release of bronchoactive mediators. We examined whether pretreatment with LY171883, a competitive antagonist of leukotriene D4 activity via LTD4 receptors, reduced the bronchospastic response to cold air ISH in asthmatics using a randomized, double-blind, two-phase crossover design. In 20 subjects, 2 wk of treatment with either LY171883 600 mg twice a day or placebo did not result in a change in FEV1 (3.45 +/- 0.21 L placebo versus 3.59 +/- 0.20 L LY171883; p greater than 0.05). Nineteen subjects underwent cold-air ISH; LY171883 increased the geometric mean respiratory heat loss required to reduce the FEV1 by 20% (PD20RHE) from 1.00 kcal/min with placebo to 1.24 kcal/min with LY171883 (p less than 0.05). A similar difference was noted when responses were expressed as a function of minute ventilation. LY171883 produced greater shifts in the PD20RHE in more reactive subjects (r = 0.69, p less than 0.002). Among 11 different symptom scores recorded by 18 subjects, there was a significant decrease in daytime chest tightness with LY171883 (p less than 0.03). The increase in PD20RHE while the subjects received LY171883 is consistent with the hypothesis that LTD4 becomes available during cold-air ISH and may mediate bronchoconstriction. The small magnitude of the effect on the PD20RHE may be due to the role of other mediators in cold-air-induced bronchoconstriction or, alternatively, to an inadequate blockade of LTD4 effects.
Gerard, C., K. R. Bhaskar, et al. (1989). "Studies on the peptide core of human bronchial mucus glycoprotein." Symp Soc Exp Biol 43: 221-30.
We have employed thiol-Sepharose chromatography following deglycosylation to analyze the protein core of bronchial epithelial mucus glycoprotein (MGP), isolated by a two stage density gradient ultracentrifugation. Deglycosylation using triflouromethanesulfonic acid resulted in loss of greater than 90% of carbohydrate. The deglycosylated core protein was reduced and the sulfhydryl residues activated with 2-2'dipyridyl disulfide. This preparation was then bound covalently to thiol-Sepharose, and eluted specifically with reducing agents. Our results demonstrate that bronchial MGP contains cysteine residues potentially capable of forming disulfide bonds. Pepsin digestion studies suggest that cysteine residues are present near both the heavily glycosylated region and the naked peptide region. Thiol-Sepharose chromatography resolved several mucin-associated proteins (MAPS) that did not bind to the column. Amino acid analysis showed that the largest of these (200 kDa) is enriched in serine/threonine, like MGP that absorbed to the column: the two smallest (20 kDa and 60 kDa) are similar to the proline rich proteins reported in salivary mucin. These associated proteins, although not linked by disulfide bonds to the MGP, are, nevertheless, tightly bound to it, since they were only recovered after deglycosylation and thiol chromatography.
Gerard, N. P., M. K. Hodges, et al. (1989). "Characterization of a receptor for C5a anaphylatoxin on human eosinophils." J Biol Chem 264(3): 1760-6.
The complement anaphylatoxin peptide C5a is well known to activate human polymorphonuclear leukocytes through receptor-mediated processes. C5a has also been reported to activate eosinophils for both chemotaxis and hexose uptake. We characterized the receptor molecule for human C5a on human eosinophils and compared it with the receptor on human neutrophils. At 4 degrees C, uptake of 1 nM 125I-C5a reaches equilibrium within 10 min on both cell types. Binding of 125I-C5a occurs over a concentration range comparable to that which stimulates lysosomal enzyme release and hexose uptake in both cell types. Scatchard analyses of the data indicate the presence of two receptor populations on eosinophils; a high affinity receptor with 15,000-20,000 sites/cell and a Kd of 3.1 +/- 0.6 x 10(-11) M, and a low affinity receptor with approximately 375,000 sites/cell and a Kd of 1 x 10(-7) M. Parallel experiments with neutrophils indicate the presence of a single receptor population with approximately 90,000 sites/cell and a Kd of 4.8 +/- 0.1 x 10(-10)M. The eosinophil receptor molecule was further characterized by covalently cross-linking 125I-C5a to cells followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the solubilized material. Autoradiography indicates the presence of a dominant C5a-eosinophil receptor complex with an apparent mass of 60-65 kDa. The corresponding neutrophil-C5a receptor complex has an apparent mass of 50-52 kDa as observed by others. When the cross-linked 125I-C5a-receptor complex was treated with cyanogen bromide, different patterns were observed on sodium dodecyl sulfate-polyacrylamide gel electrophoresis for neutrophils and eosinophils. Thus, human eosinophils have a receptor for C5a anaphylatoxin which appears to be distinct from the C5a receptor present on human neutrophils.
Drazen, J. M., S. A. Shore, et al. (1989). "Enzymatic degradation of neuropeptides: a possible mechanism of airway hyperresponsiveness." Prog Clin Biol Res 297: 45-55; discussion 55-6.
Drazen, J. M., S. A. Shore, et al. (1989). "Substance P-induced effects in guinea pig lungs: effects of thiorphan and captopril." J Appl Physiol 66(3): 1364-72.
The effects of the neutral metalloendopeptidase inhibitor, thiorphan, and the angiotensin-converting enzyme inhibitor, captopril, on the changes in airway opening pressure (PaO), pulmonary arterial pressure (Ppa), and weight induced by intravascular administration of substance P were examined in isolated perfused and ventilated guinea pig lungs. Administration of 1 nmol substance P without enzyme inhibitors resulted in a significant (P less than 0.01) increase in the peak PaO during ventilation from 12.4 +/- 0.5 to 22.4 +/- 2.2 cmH2O; there were small statistically insignificant increases in Ppa. The changes in PaO peaked approximately 30 s after peptide infusion and returned to preinfusion values by 5 min. In the presence of combined thiorphan (5.6 microM) and captopril (7.7 microM) the magnitude of the Pao response at 30 s (41.5 +/- 3.8 cmH2O) and at 5 min (40.0 +/- 3.6 cmH2O) after peptide infusion was significantly greater than in control lungs (P less than 0.05). The effects of substance P on PaO in the presence of the various inhibitors were not related to amount of peptide recovered in the lung effluent. Reverse-phase high-performance liquid chromatographic analysis of [3H]Pro2,4 substance P perfused through the lungs demonstrated that the major products were consistent with intact substance P, substance P 1-4, and smaller peptides; only minor amounts of products consistent with substance P 1-7, 1-9, or 3-11 were identified. These data support our previous findings showing that the physiological effects of intravascular substance P are limited by peptide degradation; the latter process, once begun, proceeds rapidly to nearly complete peptide degradation.
Drazen, J. M. and C. Gerard (1989). "Reversing the irreversible." N Engl J Med 320(23): 1555-6.
Watson, J. W., J. M. Drazen, et al. (1988). "Synergism between inflammatory mediators in vivo. Induction of airway hyperresponsiveness to C3a in the guinea pig." Am Rev Respir Dis 137(3): 636-40.
The complement anaphylatoxin C3a causes acute bronchoconstriction after intravenous infusion in guinea pigs. At doses of 6 to 600 micrograms/kg, the peptide causes significant and dose-dependent increases in resistance (RL) and decreases in dynamic compliance (Cdyn). Inhibition of serum carboxypeptidase N, the enzyme thought to be responsible for control of C3a activity in blood, by pretreating animals with DL-2-mercaptomethyl-3-guanidinoethylthiopropanoic acid (MGPA), resulted in a 4-fold potentiation of the response to 200 micrograms/kg C3a. Responses to lower C3a doses were not significantly affected. Pretreating animals intravenously with histamine prior to administration of C3a resulted in potentiation of C3a-induced bronchoconstriction at all doses tested, decreasing the amount of C3a required to double RL by 15-fold, from 110 to 7 micrograms/kg. The effect appears to be relatively specific for C3a since histamine pretreatment did not alter airway responsiveness to methacholine. Similarly, pretreatment with methacholine at a dose that caused an increase in RL comparable to histamine did not alter subsequent responses to C3a. Administration of capsaicin, under conditions that elicit acute release of endogenous substance P, also resulted in potentiation of C3a responses, to an extent similar to that observed for histamine. These data are consistent with an increase in pulmonary vascular permeability facilitating accessibility of C3a for its receptor to cause bronchoconstriction before it is inactivated by serum carboxypeptidase N. Further, when C3a is generated in the presence of histamine-and/or substance-P-releasing agents, it may be responsible for a greater fraction of altered pulmonary mechanics than has previously been appreciated.
Venugopalan, C. S., H. J. Jenkins, et al. (1988). "The functional conversion hypothesis: a contributor to exercise-induced asthma?" Med Hypotheses 27(4): 295-301.
Studies on receptor stability suggest that functional conversion of adrenoceptors between alpha and beta can occur in mammalian myocardium due to variations in the environment such as temperature changes, pH or hormonal changes. If adrenoceptors of the respiratory system behave similarly, heat and water loss of airways noted during hyperventilation could lead to functional loss of inhibitory beta and expression of excitatory alpha adrenoceptors. This would have the effect of counter-action of adrenergic homeostatic mechanisms which may be of particular importance in asthmatic subjects. The hypothesis of adrenoceptor interconversion could contribute to the airway obstruction observed during exercise in asthmatics. This concept is supported by scattered reports of the efficacy of alpha adrenergic antagonists in preventing exercise-induced asthma.
Shore, S. A. and J. M. Drazen (1988). "Airway responses to substance P and substance P fragments in the guinea pig." Pulm Pharmacol 1(3): 113-8.
Airway responses to rapid intravenous infusions of substance P (SP), selected carboxy terminal fragments (SP3-11, SP5-11, SP7-11, and SP9-11), and an amino terminal fragment (SP1-9) were measured in anesthetized, mechanically ventilated guinea pigs. The dose of each peptide required to decrease pulmonary conductance (GL) to 50% of baseline value was calculated in each animal. The order of ED50GL was: SP5-11 less than SP3-11 less than SP less than SP7-11. SP9-11 and SP1-9 were inactive at doses up to 1000 nmol/kg i.v. The effects of the neutral metalloendopeptidase (NEP) inhibitor, thiorphan, and the angiotensin converting enzyme (ACE) inhibitor, captopril, on airway responses to SP5-11 were examined in order to test the hypothesis that differences in degradation of SP and SP5-11 contribute to the difference in airway responsiveness to the two peptides. Thiorphan (0.5 mg/animal, i.v.) caused a significant decrease in ED50GL for SP5-11, as has been previously noted for SP. In contrast, captopril (1.7 mg/animal i.v.) had no effect on ED50GL for SP5-11, although it has a substantial effect on SP responses. These results indicate that while the carboxy terminal of SP is essential for peptide bronchoactivity, loss of amino terminal peptides (up to four residues) actually enhances bronchoconstrictor responses to the peptide. Part of this enhancement appears to result from differences in the degradation of SP and SP5-11 by ACE. The data suggest that cleavage of SP by dipeptidyl aminopeptidases could enhance its bioactivity.
Shore, S. A., N. P. Stimler-Gerard, et al. (1988). "Substance P-induced bronchoconstriction in the guinea pig. Enhancement by inhibitors of neutral metalloendopeptidase and angiotensin-converting enzyme." Am Rev Respir Dis 137(2): 331-6.
We tested the effects of the neutral metalloendopeptidase (NEP) inhibitor, thiorphan (0.17, 0.5, and 1.7 mg i.v), and the angiotensin-converting enzyme (ACE) inhibitor, captopril (0.5, 1.7, and 5.0 mg i.v.), on the bronchoconstrictor response to rapid intravenous infusions of substance P (0.1 to 30 nmol/kg) in anesthetized, mechanically ventilated guinea pigs. The decreases in pulmonary conductance and dynamic compliance caused by substance P were greater in animals treated with either thiorphan or captopril than in control animals. Thiorphan (0.5 mg) had no effect on airway responsiveness to intravenously administered methacholine, whereas captopril (1.7 mg) caused a small increase in methacholine responsiveness. Both drugs significantly increased the recovery of immunoreactive substance P in arterial plasma after exogenous administration of the peptide. We conclude that degradation of substance P by both NEP and ACE is important for determining the magnitude of the bronchoconstriction caused by intravenous administration of this neuropeptide. These data suggest that conditions associated with diminished peptidase activity could result in enhanced responses to stimuli which cause the release of endogenous substance P.
Martin, T. R., N. P. Gerard, et al. (1988). "Pulmonary responses to bronchoconstrictor agonists in the mouse." J Appl Physiol 64(6): 2318-23.
Mice have been used in studies of the immunology or pathology of several different disorders affecting the lung. However, the value of the mouse for the analysis of pulmonary pathophysiology has been limited by the lack of methods for measuring lung function in the living animal. We report here the first method for measuring pulmonary conductance (GL) and compliance (Cdyn) in tracheostomized mechanically ventilated mice. We used this method to characterize the mouse's pulmonary responses to several putative bronchoconstrictor agonists. GL and Cdyn were decreased by intravenous infusions of methacholine, norepinephrine, or serotonin. Reproducible responses were not detected after infusions of histamine, prostaglandins D2 or F2 alpha, leukotrienes C4 or D4, substance P, or platelet-activating factor. The pattern of airway responsiveness to these agonists in the mouse is similar to that reported for the rat; in contrast to the rat, the mouse has many well-characterized strains or mutants with deficiencies of immunologic or inflammatory cells or mediators. As a result, this model offers unique advantages for identifying the roles of individual inflammatory cell types or mediators in pulmonary processes, including pulmonary anaphylaxis.
Ludwig, M. S., S. A. Shore, et al. (1988). "Temporal and regional variability of collateral resistance response to histamine." J Appl Physiol 64(5): 2142-9.
Using the wedged bronchoscope technique, we measured the changes in collateral resistance (Rcoll) in dogs resulting from exposure to aerosols of increasing concentrations of histamine. Histamine dose-response curves were performed in each of two to three separate lobar segments of an individual mongrel dog's lungs. Five dogs were studied. The same segments were reexamined on later occasions (2-11 wk apart) to determine whether the responsiveness to histamine had altered with time. Measurements of base-line Rcoll for a given segment were reproducible (coefficient of variation 0.48). In contrast, we observed that the estimated dose of histamine required to increase Rcoll by 50% (ED150Rcoll) was extremely variable both among lung segments of an individual dog on a single experimental day (geometric mean variability of 40-fold) and for a given segment when reexamined on repeated occasions (geometric mean variability of 47-fold). The ED150Rcoll did not correlate with the base-line Rcoll. The degree of variability we observed suggests that peripheral contractile elements are under the influence of powerful local modulating factors that vary both regionally and temporally.
Ludwig, M. S., S. A. Shore, et al. (1988). "Differential responses of tissue viscance and collateral resistance to histamine and leukotriene C4." J Appl Physiol 65(3): 1424-9.
Alterations in tissue viscance (Vti) and collateral resistance (Rcoll) are both used as indexes of peripheral lung responses. However, it is not known whether the two responses reflect the effects of activation of the same contractile elements. We measured differential responses in Vti and Rcoll to histamine and leukotriene (LT) C4 to determine whether each evoked a similar pattern of response. Using the wedged bronchoscope constant-flow technique, we measured Rcoll in lobar segments of anesthetized, paralyzed, open-chest, mechanically ventilated mongrel dogs. In addition, we measured (with an alveolar capsule) alveolar pressure (PA) within the segment under study. This allowed us to calculate Vti, the component of the PA change in phase with segment flow. Rcoll and Vti measurements were obtained under base-line conditions and after local delivery of aerosols generated from histamine and LTC4. In five out of five lobes studied with both histamine and LTC4, the fractional Rcoll response to histamine was greater than the fractional Rcoll response to LTC4. In contrast, in four out of five lobes examined, the fractional increase in Vti accompanying the histamine response was less than the fractional increase in Vti accompanying LTC4 administration. These data suggest that anatomically distinct contractile elements influence Vti and Rcoll insofar as LTC4 and histamine evoke quantitatively different changes in these two indexes of peripheral lung responses.
Kariya, S. T., S. A. Shore, et al. (1988). "Methacholine-induced bronchoconstriction in dogs: effects of lung volume and O3 exposure." J Appl Physiol 65(6): 2679-86.
The maximal effect induced by methacholine (MCh) aerosols on pulmonary resistance (RL), and the effects of altering lung volume and O3 exposure on these induced changes in RL, was studied in five anesthetized and paralyzed dogs. RL was measured at functional residual capacity (FRC), and lung volumes above and below FRC, after exposure to MCh aerosols generated from solutions of 0.1-300 mg MCh/ml. The relative site of response was examined by magnifying parenchymal [RL with large tidal volume (VT) at fast frequency (RLLS)] or airway effects [RL with small VT at fast frequency (RLSF)]. Measurements were performed on dogs before and after 2 h of exposure to 3 ppm O3. MCh concentration-response curves for both RLLS and RLSF were sigmoid shaped. Alterations in mean lung volume did not alter RLLS; however, RLSF was larger below FRC than at higher lung volumes. Although O3 exposure resulted in small leftward shifts of the concentration-response curve for RLLS, the airway dominated index of RL (RLSF) was not altered by O3 exposure, nor was the maximal response using either index of RL. These data suggest O3 exposure does not affect MCh responses in conducting airways; rather, it affects responses of peripheral contractile elements to MCh, without changing their maximal response.
Ingenito, E., J. Solway, et al. (1988). "Dissociation of temperature-gradient and evaporative heat loss during cold gas hyperventilation in cold-induced asthma." Am Rev Respir Dis 138(3): 540-6.
We examined temperature-gradient and evaporative energy losses during cold gas inhalation challenges in patients with exercise-induced asthma by using gases with similar water-carrying capacities but significantly different volume heat capacities. Seven subjects were asked to hyperventilate mixtures of 80% helium/20% oxygen (HeO2) or 80% sulfur hexafluoride/20% oxygen (SF6O2) for 5 min at a fixed target minute ventilation of 20 x FEV1 and an inspired gas temperature of 0 degrees C. Each subject equilibrated his or her lungs with the appropriate gas mixture prior to testing: PETCO2 and FIO2 were monitored and maintained at constant values (CO2 = 0.05; O2 = 0.20) by CO2 scrubbing and addition of compressed gas to the system. Gas composition, inspired and expired flow rates, and gas temperatures at the airway opening were recorded in real time using a computer-based data collection system that calculated respiratory heat loss on a per breath basis. Bronchoconstriction was quantitated using specific airway conductance measured before and serially after each challenge. The degree of bronchoconstriction correlated closely with evaporative respiratory heat loss (r = 0.658 p less than 0.05), but poorly with both temperature-gradient (r = 0.114, p greater than 0.20) and total (r = 0.268, p greater than 0.15) heat loss. These findings suggest that total respiratory heat loss is not the primary stimulus in exercise-induced asthma, and further suggest that total water loss, or focal heat/water loss, may be important in inducing bronchospasm in this subset of asthmatics.
Hodges, M. K., P. F. Weller, et al. (1988). "Heterogeneity of leukotriene C4 production by eosinophils from asthmatic and from normal subjects." Am Rev Respir Dis 138(4): 799-804.
We evaluated the formation of leukotriene C4 (LTC4) by peripheral blood eosinophils of different densities obtained from asthmatic and normal subjects. When stimulated with 1 microgram/ml of the calcium ionophore A23187 for 15 min at 37 degrees C, eosinophils with densities greater than 1.093 g/ml from asthmatic and normal subjects released 19.1 +/- 4.2 ng LTC4/10(6) eosinophils and 23.9 +/- 5.0 ng LTC4/10(6) eosinophils, respectively. In contrast, lower density eosinophils (densities 1.093 g/ml or less) isolated from the asthmatic subjects released significantly less LTC4 than did eosinophils of similar densities from normal subjects (41.6 +/- 3.0 versus 79.0 +/- 6.7 ng LTC4/10(6) eosinophils, p less than 0.05). Differences could not be demonstrated between the two subject groups in LTC4 metabolism, time course of extracellular release of LTC4, or dose response to A23187, nor were interactions between eosinophils and neutrophils with regard to LTC4 release evident. Thus, hypodense eosinophils elaborate greater quantities of LTC4 than do eosinophils of normal density whether obtained from normal or asthmatic subjects. However, the finding that peripheral blood eosinophils from asthmatic subjects have decreased capacity for the synthesis of LTC4 compared with cells of similar densities isolated from normal subjects demonstrates that the capacity of eosinophils to produce LTC4 is regulated by factors that are not necessarily reflected in the cell density.
Drazen, J. M. (1988). "Comparative contractile responses to sulfidopeptide leukotrienes in normal and asthmatic human subjects." Ann N Y Acad Sci 524: 289-97.
Bhaskar, K. R., J. M. Drazen, et al. (1988). "Transition from normal to hypersecretory bronchial mucus in a canine model of bronchitis: changes in yield and composition." Exp Lung Res 14(1): 101-20.
Density-gradient analysis was used to follow the transition from normal to hypersecretory bronchial mucus in a model of bronchitis induced in dogs by chronic exposure to SO2 gas. Aspirates of saline bronchial lavage were obtained by fiberoptic bronchoscopy from dogs before, during a 6- to 9-month exposure period to SO2 gas, and during a recovery period of similar duration. Prior to SO2 exposure, aspirates from all animals had a low yield of nondialyzable macromolecules (15 +/- 6 mg/aspirate) and similar composition. Specifically, epithelial glycoprotein of typical buoyant density was not detected; rather a glycoconjugate of higher buoyant density with features of both proteoglycan and glycoprotein was identified. Neutral lipids were predominant with lesser amounts of phospholipids; no glycolipids were detected. During the SO2 exposure period, aspirates from five of the eight dogs contained components similar in buoyant density to human bronchitic glycoprotein. Glycoprotein isolated from the canine aspirates was similar to glycoprotein isolated from human chronic bronchitic sputum, having the same carbohydrate composition and range of oligosaccharide size. Further, during and after SO2 exposure some aspirates contained appreciable amounts of glycolipids. These data demonstrate substantial similarities in composition between normal human and canine mucus and in mucus isolated from dogs with chronic airway inflammation induced by repeated irritant exposure and from human patients with chronic bronchitis.
Solway, J., J. J. Fredberg, et al. (1987). "Interdependent regional lung emptying during forced expiration: a transistor model." J Appl Physiol 62(5): 2013-25.
We recognized similarities between isovolume pressure-flow curves of the lung and emitter-collector voltage-current characteristics of bipolar transistors, and used this analogy to model expiratory flow limitation in a two-generation branching network with parallel nonhomogeneity. In this model, each of two bronchi empty parenchymal compliances through a common trachea, and each branch includes resistances upstream and downstream of a flow-limiting site. Properties of each airway are specified independently, allowing simulation of differences between the tracheal and bronchial generations and between the parallel bronchial paths. Simulations of four types of parallel asymmetry were performed: unilateral peripheral bronchoconstriction; unilateral central bronchoconstriction; asymmetric redistribution of parenchymal compliance; and unilateral alteration of the bronchial area-transmural pressure characteristic. Our results indicate that multiple axial choke points can exist simultaneously in a symmetric lung when large airway opening-pleural pressure gradients exist; despite severe nonhomogeneity of regional lung emptying, flow interdependence among parallel branches tends to maintain a near normal configuration of the overall maximal expiratory flow-volume (MEFV) curve throughout a large fraction of the vital capacity; and sudden changes of slope of the MEFV curve ("knees" or "bumps") may reflect choking in one branch in a nonuniform lung, but need not be obvious even when severe heterogeneity of lung emptying exists.
Shore, S. A., S. T. Kariya, et al. (1987). "Sulfur-dioxide-induced bronchitis in dogs. Effects on airway responsiveness to inhaled and intravenously administered methacholine." Am Rev Respir Dis 135(4): 840-7.
Chronic bronchitis was induced in 7 dogs of mixed breed by chronic exposure to SO2 gas. Within the first 2 to 4 wk of exposure, the dogs developed cough and mucous hypersecretion, chronic airway obstruction (increased pulmonary resistance), and persistent lung inflammation as demonstrated by an increase in the number of neutrophils recovered in the bronchoalveolar lavage (BAL) fluid. Airway responsiveness to methacholine aerosol decreased 2- to 3-fold within 8 wk of SO2 exposure. In contrast, airway responsiveness to intravenous administration of methacholine did not change. The data suggest that the decreased airway responsiveness observed during persistent pulmonary inflammation in SO2-exposed dogs is not due to an altered state of airway contractile elements but likely reflects expression of an inhibitory influence of the mucoepithelial barrier.
Shore, S. A., N. P. Stimler-Gerard, et al. (1987). "A formyl peptide contracts guinea pig lung: role of arachidonic acid metabolites." J Appl Physiol 63(6): 2450-9.
We studied the role of cyclooxygenase and lipoxygenase products of arachidonic acid metabolism in mediating N-formyl-methionyl-leucyl-phenylalanine- (FMLP) induced contractions of guinea pig lung parenchymal strips. The cyclooxygenase inhibitors indomethacin (10(-5) M) and aspirin (3 X 10(-5) to 10(-4) M), the lipoxygenase inhibitor nordihydroguaiaretic acid (10(-5) to 3 X 10(-5) M), and the combined cyclooxygenase/lipoxygenase inhibitors 1-phenyl-3-pyrazolidinone (Phenidone) (3 X 10(-5) to 3 X 10(-4) M) and BW 755C (10(-5) to 10(-4) M) each caused a decrease in the maximum force induced by FMLP (Fmax) and an increase in the concentration of FMLP required to produce 50% of Fmax (EC50). The thromboxane synthesis inhibitor imidazole (3 X 10(-3) M) also decreased Fmax. The leukotriene D4 receptor antagonist FPL 55712 (5.7 X 10(-6) to 1.9 X 10(-5) M) increased the EC50 for FMLP, whereas desensitization of lung parenchymal strips to leukotriene B4 by pretreatment with this leukotriene (10(-7) M) had no effect on FMLP-induced contraction. After exposure to FMLP (10(-6) M), guinea pig lung produced (as determined by high-performance liquid chromatography and radioimmunoassay) leukotrienes C4 and B4, thromboxane A2 (as measured by its stable degradation product thromboxane B2), and prostaglandin F2 alpha. Lung strips not exposed to FMLP showed no evidence of leukotriene production. We conclude that thromboxane A2 and leukotriene C4 generated in response to FMLP mediate a substantial fraction of the force induced by this peptide in guinea pig lung parenchymal strips.
Schwartzstein, R. M., M. Kelleher, et al. (1987). "Airway effects of monosodium glutamate in subjects with chronic stable asthma." J Asthma 24(3): 167-72.
We studied the effect of oral monosodium glutamate (MSG) on airways function in 12 subjects with a history of chronic stable asthma in a double-blind, randomized, crossover protocol. Subjects ingested either 25 mg/kg of MSG or sodium chloride (equimolar to MSG) following a 6-hour fast. Spirometry [forced expiratory volume in 1 second (FEV1) and forced vital capacity] was performed before administration of the test substances and for a minimum of 4 hours thereafter. At no time during the observation period was the mean change in FEV1 more negative following MGS than following placebo. MSG is unlikely to be a contributing factor in bouts of bronchospasm in subjects with asthma, and routine avoidance of MSG by individuals with asthma need not be advised.
Scanlon, P. D., J. Seltzer, et al. (1987). "Chronic exposure to sulfur dioxide. Physiologic and histologic evaluation of dogs exposed to 50 or 15 ppm." Am Rev Respir Dis 135(4): 831-9.
Seven adult mongrel dogs were exposed to SO2 gas at 2 different concentrations (15 and 50 ppm) on a daily basis for 5 to 11 months. Mucous hypersecretion and airway obstruction (a sustained increase in pulmonary resistance) developed in 4 dogs exposed to 50 ppm SO2. Histologic examination of the dogs' airways demonstrated epithelial thickening and an increase in size of the mucous glands. No inflammatory cell infiltration of the airways was noted and, in addition, responsiveness to inhaled histamine and methacholine did not change. The increase in lung resistance correlated with increase in mucous gland volume and airway wall thickening, but not with any change in airway responsiveness. Dogs exposed to 15 ppm SO2 showed minimal histologic and physiologic changes compared with control dogs. Previous work with a similar model of chronic bronchitis, using higher level SO2 exposure, has demonstrated an association of airway inflammation with decreased responsiveness to inhaled bronchoconstrictors. In the present study, with a lower exposure level to SO2 (50 versus 200 ppm), we found similar histologic findings associated with airway obstruction, but in the absence of airway inflammation, responsiveness to inhaled bronchoconstrictors was unchanged. This supports the theory that chronic airway inflammation may be associated with decreased responsiveness to inhaled bronchoconstrictors. This contrasts with the hyperresponsiveness induced by acute exposure to irritant gases noted by others.
Israel, E., J. L. Robin, et al. (1987). "Differential effects of calcium channel blockers on leukotriene C4- and D4-induced contractions in guinea pig pulmonary parenchymal strips." J Pharmacol Exp Ther 243(2): 424-9.
Leukotriene (LT)C4 and LTD4-induced contractile effects in guinea pig pulmonary parenchyma were distinguished by their sensitivity to calcium channel blockers. LTC4-induced contractions were inhibited in a noncompetitive manner in the presence of calcium channel blockers, whereas LTD4 contractions were unaffected. In the presence of diltiazem, maximum LTC4-induced (1 X 10(-7) M) contractions were reduced by 24% and the concentration-effect curve was shifted to the right in a nonparallel manner; diltiazem had no significant effect on the LTD4 response. We used this differential sensitivity to calcium channel blockade to permit pharmacological characterization in guinea pig pulmonary parenchyma of the interaction of the competitive LT blocker FPL55712 and the putative LTD4 receptor, LTRd. We showed, using [3H]LTC4, that at least 15% of LTC4 is converted to LTD4 under our experimental conditions. We performed a Schild analysis of the inhibition of LTD4-induced contractions by FPL55712 in the presence of the calcium channel blocker diltiazem (0.67 mM). The Kb derived from this analysis (3.2 X 10(-7) M) agrees closely with the Ki derived for the interaction of FPL55712 and specific LTD4 binding in lung membranes. A Schild analysis of the interaction of FPL55712 and LTC4 in the presence of diltiazem resulted in competitive inhibition with a Kb of 4.7 X 10(-7) M. This apparent competitive inhibition, combined with the similarity of these binding constants, suggests that diltiazem is effective in blocking LTC4-mediated responses and that when these effects are blocked, LTC4 induced contractions are mediated through LTRd. The differential effects of calcium blockade on these two agonists provides evidence for distinct coupling mechanisms for LT receptors in this tissue.
Ingenito, E. P., J. Solway, et al. (1987). "Indirect assessment of mucosal surface temperatures in the airways: theory and tests." J Appl Physiol 63(5): 2075-83.
We developed and tested a method, based on conduction heat transfer analysis, to infer airway mucosal temperatures from airstream temperature-time profiles during breath-hold maneuvers. The method assumes that radial conduction of heat from the mucosal wall to inspired air dominates heat exchange during a breath-hold maneuver and uses a simplified conservation of energy analysis to extrapolate wall temperatures from air temperature vs. time profiles. Validation studies were performed by simultaneously measuring air and wall temperatures by use of a retractable basket probe in the upper airways of human volunteers and intrathoracic airways of paralyzed intubated dogs during breath holding. In both protocols, a good correlation was demonstrated between directly measured wall temperatures and those calculated from adjacent airstream temperature vs. time profiles during a breath hold. We then calculated intrathoracic bronchial wall temperatures from breath-hold airstream temperature-time profiles recorded in normal human subjects after cold air hyperpnea at 30 and 80 l/min. The calculations show airway wall temperatures in the upper intrathoracic airways that are below core body temperature during hyperpnea of frigid air and upper thoracic airways that are cooler than more peripheral airways. The data suggest that the magnitude of local intrathoracic heat/water flux is not represented by heat/water loss measurements at the airway opening. Both the magnitude and locus of heat transport during cold gas hyperventilation vary with changes in inspired gas temperature and minute ventilation; both may be important determinants of airway responses.
Fanta, C. H., J. W. Watson, et al. (1987). "In vivo bronchodilator activity of nifedipine in the guinea pig." Am Rev Respir Dis 136(1): 76-9.
We administered histamine subcutaneously to anesthetized guinea pigs to induce prolonged bronchoconstriction and then tested the effect of intravenously administered nifedipine on pulmonary resistance (RL) and dynamic compliance (Cdyn). One mg of subcutaneously administered histamine caused RL to increase by an average of more than 250% and Cdyn to fall on average to 26% of baseline; mean RL remained more than twice baseline, and mean Cdyn remained less than half baseline for 80 min. Intravenously administered nifedipine 3 micrograms/kg and ethanol (diluent) administered 25 min after histamine had no effect on RL but caused a slightly greater fall in Cdyn than in the control animals treated with histamine alone. Nifedipine 30 micrograms/kg, however, exhibited significant bronchodilator activity: 35 min after nifedipine 30 micrograms/kg, RL decreased on average to 41 +/- 17% above baseline (p less than 0.02), and Cdyn increased to 49 +/- 5% below baseline (p less than 0.0001). By comparison, isoproterenol (0.3 to 3.0 micrograms/kg) caused bronchodilation of more rapid onset (within 1 min) and shorter duration of action (approximately 10 min). Thus, we were able to demonstrate bronchodilator activity of nifedipine in vivo, as had been predicted by in vitro studies of guinea pig and human tracheal strips. These results would appear to justify continued exploration of the potential role for calcium channel blockers in the treatment of obstructive lung disease.
Drazen, J. M., H. A. Boushey, et al. (1987). "The pathogenesis of severe asthma: a consensus report from the Workshop on Pathogenesis." J Allergy Clin Immunol 80(3 Pt 2): 428-37.
Drazen, J. M. and K. F. Austen (1987). "Leukotrienes and airway responses." Am Rev Respir Dis 136(4): 985-98.
Davidson, A. B., T. H. Lee, et al. (1987). "Bronchoconstrictor effects of leukotriene E4 in normal and asthmatic subjects." Am Rev Respir Dis 135(2): 333-7.
The bronchoconstrictor activity of an aerosol of leukotriene E4(LTE4) was compared with that of histamine in 5 normal and in 6 asthmatic subjects to define the relative potency of LTE4 between the groups using 3 indices of airway response. The FEV1 and the flow rate measured at 30% of vital capacity from partial and maximal expiratory maneuvers (V30-P and V30-M) were measured. The geometric mean (GSEM) concentration of LTE4 required to reduce the V30-P by 30% was 0.30 (1.46) mM in the normal subjects, and 0.058 (1.63) in the asthmatic subjects; LTE4 was 39-fold more potent than histamine in the former and 14-fold in the latter group. Further, we observed that when normal and asthmatic subjects were compared at a degree of bronchoconstriction resulting in a 30% decrement in the V30-P after inhaling LTE4, there was a greater response in the asthmatic group than in the normal group of the accompanying change in the FEV1. The decrements in the FEV1 were not significantly different between the 2 groups after inhaling histamine. This study demonstrates that LTE4 is a potent bronchoconstrictor agonist in humans and suggests that airway responsiveness to this agonist differs substantially with the index of bronchoconstriction used for assessment of airway response.
Davidson, A. B., C. A. Hirshman, et al. (1987). "Large-volume ventilation results in bronchoconstriction of Basenji-Greyhound dogs." J Appl Physiol 62(6): 2308-13.
We compared the effects of large-volume ventilation on airway responses to aerosolized histamine in anesthetized mongrel dogs with its effects in Basenji-Greyhound crossbred (B-G) dogs. Before bronchoconstriction, large inflations resulted in only small changes of dynamic compliance (Cdyn) and pulmonary resistance (RL) in both groups of dogs. After the induction of a moderate degree of bronchoconstriction with aerosolized histamine, large inflations had a more substantial effect; Cdyn increased by 7.5 +/- 2.3% (mean +/- SE; P less than 0.05), and RL decreased by 32 +/- 3.4% (P less than 0.001) in the mongrel dogs. In the B-G group, Cdyn increased by only 0.2 +/- 1.8% (NS), and RL increased by 29.3 +/- 9.2% (P less than 0.05); these changes differed significantly (P less than 0.05) from those observed in the mongrel dogs. Large-volume ventilation following the administration of indomethacin (10 mg/kg iv) and histamine increased Cdyn by 11.4 +/- 1.8% (NS vs. without indomethacin) and decreased RL by 43.9 +/- 3.4% (P less than 0.05) in the mongrel group. In the B-G group large-volume ventilation increased Cdyn by 7.6 +/- 1.7% (P less than 0.01) and decreased RL by 15.7 +/- 8.1% (P less than 0.05). Thus indomethacin enhanced the bronchodilator effects of large-volume ventilation in mongrel dogs and reversed the bronchoconstrictor effect of this maneuver on RL in B-G dogs.
Butler, J. P., J. L. Lehr, et al. (1987). "Longitudinal elastic wave propagation in pulmonary parenchyma." J Appl Physiol 62(4): 1349-55.
Consideration of the lung as an elastic continuum led us to investigate the possible propagation of elastic waves. Here the relevant stiffness and density are given by the Lame constants and density of the parenchyma. To test this hypothesis, we measured propagation velocities (c) in dog lobes by recording transit times of a velocity impulse on one side of the lobe and the subsequent arrival on the other side. We compared our measured values of c with elastic longitudinal wave velocities (c long) predicted by values of elastic moduli given by Lai-Fook et al. (J. Appl. Physiol. 40: 508-513, 1976) as a function of translobar pressure (PL) and our measured densities. Good agreement was found between c and c long. Typical values of c ranged from 250-1,500 cm/s as PL ranged from 2-20 cmH2O. No systematic difference in the c-c long relation was found between inflation and deflation, suggesting that the elastic moduli of lungs are essentially a function of pressure. No significant effect was observed by changing the physical properties of the gas within the lobe [air vs. He vs. sulfur hexafluoride (SF6)], suggesting that indeed we were observing waves associated with the coupling of parenchymal density to parenchymal stiffness.
Watson, J. W., A. C. Jackson, et al. (1986). "Effect of lung volume on pulmonary mechanics in guinea pigs." J Appl Physiol 61(1): 304-11.
The lung volume (VL) dependence of several dynamic pulmonary mechanical properties of the guinea pig lung were determined over the range of the vital capacity (10-100% VC) with the vagi intact and sectioned. We found dynamic compliance to be strongly VL dependent, decreasing as much as 85% between functional residual capacity (FRC) and total lung capacity (TLC). Below FRC, dynamic compliance either remained unchanged or decreased, depending upon the technique used in its measurement. Pulmonary resistance (RL) decreased monotonically with increasing VL, whereas pulmonary conductance was linearly related to VL. Conductance was much less sensitive to VL than compliance, increasing only 28% between FRC and TLC. The sensitivity of pulmonary conductance to VL was substantially increased by subtracting the resistance of the tracheal cannula from RL. Specific pulmonary conductance was not independent of VL but decreased approximately 45% over the range of the VC. Pulmonary inertance was found to be unaffected by VL. Extrapolation from these data indicate that small differences in FRC, which might be expected within and between studies relying on pulmonary mechanical measurements, would most strongly affect compliance estimates and only moderately alter resistance estimates. It also indicates that the use of specific pulmonary conductance does not remove VL as an independent variable.
Venugopalan, C. S., H. J. Jenkins, et al. (1986). "Effect of temperature on beta receptor responsiveness in guinea pig pulmonary tissues." Res Commun Chem Pathol Pharmacol 53(3): 275-88.
Cumulative concentration-effect relationships of isoproterenol (isoprenaline) on guinea pig tracheal spirals and lung parenchymal strips were determined in organ baths kept at 37 degrees C or at 18 degrees C. The IC50's for isoproterenol at 18 degrees C were significantly (p less than .01) higher than those for isoproterenol at 37 degrees C in both the tissues; although the parenchymal response was affected more than that of the trachea by cooling. pA2 values for propranolol were determined on both tracheal spirals and parenchymal strips at 37 degrees C and 18 degrees C. The pA2 values were decreased in both the tissues by cooling. The decrease was more prominent in the parenchyma than in the trachea, a finding consistent with the concentration-effect relationships studies mentioned above.
Solway, J., T. H. Rossing, et al. (1986). "Expiratory flow limitation and dynamic pulmonary hyperinflation during high-frequency ventilation." J Appl Physiol 60(6): 2071-8.
Dynamic hyperinflation of the lungs occurs during high-frequency oscillatory ventilation (HFOV) and has been attributed to asymmetry of inspiratory and expiratory impedances. To identify the nature of this asymmetry, we compared changes in lung volume (VL) observed during HFOV in ventilator-dependent patients with predictions of VL changes from electrical analogs of three potential modes of impedance asymmetry. In the patients, when a fixed oscillatory tidal volume was applied at a low mean airway opening pressure (Pao), which resulted in little increase in functional residual capacity, progressively greater dynamic hyperinflation was observed as HFOV frequency, (f) was increased. When mean Pao was raised so that resting VL increased, VL remained at this level during HFOV as f was increased until a critical f was reached; above this value, VL increased further with f in a fashion nearly parallel to that observed when low mean Pao was used. Three modes of asymmetric inspiratory and expiratory impedance were modeled as electrical circuits: 1) fixed asymmetric resistance [Rexp greater than Rinsp]; 2) variable asymmetric resistance [Rexp(VL) greater than Rinsp, with Rexp(VL) decreasing as VL increased]; and 3) equal Rinsp and Rexp, but with superimposed expiratory flow limitation, the latter simulated using a bipolar transistor as a descriptive model of this phenomenon. The fixed and the variable asymmetric resistance models displayed a progressive increase of mean VL with f at either low or high mean Pao. Only the expiratory flow limitation model displayed a dependence of dynamic hyperinflation on mean Pao and f similar to that observed in our patients. We conclude that expiratory flow limitation can account for dynamic pulmonary hyperinflation during HFOV.
Solway, J., A. R. Leff, et al. (1986). "Circulatory heat sources for canine respiratory heat exchange." J Clin Invest 78(4): 1015-9.
We assessed the roles of the pulmonary and bronchial circulations as potential heat sources to the pulmonary airways during respiratory heat loss, by observing the changes in airstream temperature that accompanied temporary occlusion of the pulmonary or bronchial circulations. Baseline end-expiratory and end-inspiratory airstream temperatures were 35.4 +/- 0.2 degrees C (SEM) and 30.9 +/- 0.3 degrees C, respectively, among all trials. With occlusion of the lower lobe pulmonary arteries for 3 min ipsilateral end-expiratory and end-inspiratory airstream temperatures fell by 2.8 +/- 0.2 and 1.1 +/- 0.2 degrees C, respectively, during hyperpnea with room temperature air, and by 3.5 +/- 0.5 and 1.8 +/- 0.2 degrees C, respectively, during hyperpnea with frigid air. In marked contrast, interruption of the bronchial circulation for 3 min had no effect on airstream temperatures. These data indicate that under these conditions, the pulmonary circulation, but not the bronchial circulation, serves as an important local heat source for respiratory heat exchange within the pulmonary airways.
Rossing, T. H. and J. M. Drazen (1986). "Effects of milrinone on contractile responses of guinea pig trachea, lung parenchyma and pulmonary artery." J Pharmacol Exp Ther 238(3): 874-9.
The effects of milrinone, a bipyridine with known vasodilator activity, on guinea pig tracheal-spirals, lung parenchymal strips and pulmonary artery rings in vitro were compared with the effects of isoproterenol and aminophylline on these tissues. The concentration of milrinone that produced 50% relaxation (IC50) of tracheal spirals constricted by carbachol was 3.6 X 10(-5) M. Isoproterenol (IC50, 9.5 X 10(-8) M) was significantly (P less than .001) more potent and aminophylline (IC50, 1.2 X 10(-4) M) was significantly (P less than .001) less potent than milrinone in this effect. The IC50 for milrinone for lung parenchymal strips contracted by histamine was 3.2 X 10(-5) M, whereas the IC50 for isoproterenol was significantly (P less than .001) less, 1.4 X 10(-7) M; aminophylline produced only limited relaxation of lung parenchymal strips. Milrinone relaxed pulmonary artery rings constricted by norepinephrine with an IC50 of 3.8 X 10(-6) M, whereas neither isoproterenol nor aminophylline produced a 50% relaxation. Pretreatment of tracheal spirals, lung parenchymal strips and pulmonary artery rings with 1.6 X 10(-4) M milrinone inhibited subsequent contraction by carbachol, histamine and norepinephrine, respectively. The relaxant effects of milrinone were not influenced by treatment with atropine, cimetidine, mepyramine, phentolamine or propranolol. However, indomethacin blocked milrinone's relaxant effects on tracheal spirals effectively, but not on pulmonary artery rings or lung parenchymal strips, suggesting distinct modes of action on various tissue types.
Lee, T. H., E. Israel, et al. (1986). "Enhancement of plasma levels of biologically active leukotriene B compounds during anaphylaxis in guinea pigs pretreated by indomethacin or by a fish oil-enriched diet." J Immunol 136(7): 2575-82.
The changes in arterial plasma concentrations of immunoreactive leukotriene B (LTB) were compared after antigen challenge of two groups of sensitized, mepyramine-treated, and mechanically ventilated guinea pigs, one fed a diet enriched with fish oil and the other a control diet enriched with beef tallow. The lung tissue of animals fed a fish oil-enriched diet (FFD) for 9 to 10 wk incorporated eicosapentaenoic acid (EPA) and docosahexaenoic acid to constitute 8 to 9% of total fatty acid content, whereas these alternative fatty acids constituted less than 1% of the total fatty acid content of the lung tissue of animals on a beef tallow-supplemented diet (BFD). The maximum increase after antigen challenge in immunoreactive LTB4 from 0.16 +/- 0.04 ng/ml to 0.84 +/- 0.25 ng/ml in BFD animals and from 0.47 +/- 0.11 to 5.1 +/- 1.4 ng/ml immunoreactive LTB (LTB4 and LTB5) in FFD animals was significant (p less than 0.02) for each. Furthermore, the increase in total immunoreactive LTB in mepyramine-treated FFD animals was significantly greater than the increase in LTB4 in mepyramine-treated BFD guinea pigs at 2 to 8 min after antigen challenge (p less than 0.05). Resolution of arterial plasma immunoreactive LTB from pooled samples by reverse-phase high-performance liquid chromatography demonstrated that the sum of LTB4 and LTB5 in FFD animals exceeded that of LTB4 in BFD animals and that the quantity of LTB4 in the FFD animals was at least as great as that in the BFD animals during anaphylaxis. The products eluting at the retention times of LTB4 and LTB5 exhibited the chemotactic activity of their respective synthetic standards. The combination of indomethacin and mepyramine markedly augmented the antigen-induced increase in arterial plasma immunoreactive LTB4 concentrations in BFD animals, but had no effect on immunoreactive LTB levels in FFD animals. Limited in vivo measurements showing a lesser increase of plasma immunoreactive thromboxane B2 in the FFD relative to the BFD animals during anaphylaxis and ex vivo measurements showing a decreased LTB4-stimulated (cyclooxygenase product-dependent) contractile response of pulmonary parenchymal strips from the FFD relative to the BFD animals provide evidence for blockade in the cyclooxygenase pathway in the FFD animals. The measurements of arterial plasma LTB indicate that indomethacin treatment alone, which inhibits cyclooxygenase activity, and FFD treatment each augment the metabolism of arachidonic acid by the 5-lipoxygenase pathway in animals pretreated with mepyramine.(ABSTRACT TRUNCATED AT 400 WORDS)
Ingenito, E. P., J. Solway, et al. (1986). "Finite difference analysis of respiratory heat transfer." J Appl Physiol 61(6): 2252-9.
A numerical computer model of heat and water transfer within the tracheobronchial tree of humans was developed based on an integral formulation of the first law of thermodynamics. Simulation results were compared with directly measured intraluminal airway temperature profiles previously obtained in normal human subjects, and a good correlation was demonstrated. The model was used to study aspects of regional pulmonary heat transfer and to predict the outcomes of experiments not yet performed. The results of these simulations show that a decrease in inspired air temperature and water content at fixed minute ventilation produces a proportionately larger increase in heat loss from extrathoracic airways relative to intrathoracic, whereas an increase in minute ventilation at fixed inspired air conditions produces the opposite pattern, with cold dry air penetrating further into the lung, and that changes in breathing pattern (tidal volume and frequency) at fixed minute ventilation and fixed inspiratory-to-expiratory (I/E) ratio do not affect local air temperature profiles and heat loss, whereas changes in I/E ratio at fixed minute ventilation do cause a significant change.
Drazen, J. M. (1986). "Inhalation challenge with sulfidopeptide leukotrienes in human subjects." Chest 89(3): 414-9.
What is the meaning of these findings to the practicing chest physician? First, leukotrienes are potent airway constrictors; they are capable of reproducing the type of airway constriction observed in asthma. The role of leukotrienes in this regard has yet to be established, but experiments to test the importance of these agents in this setting are likely to be performed soon. Specifically, several leukotriene receptor antagonists or synthesis inhibitors have been identified and may provide the tools needed to test this crucial hypothesis. Second, the leukotrienes are unique bronchoactive agents in that the degree of hyperresponsiveness between normal and asthmatic subjects varies markedly with the bronchoconstrictor index used to assess response. When one compares normal subjects to asthmatic subjects, there is substantial overlap in leukotriene sensitivity among groups when V30-P is used as the bronchoconstrictor index. However, when the FEV1 is used as the bronchoconstrictor index, there is little overlap in sensitivity between normal and asthmatic subjects, and the separation between the two groups is even more clearly made than it is with histamine or methacholine challenge. Thus, LTD4 inhalation challenge may replace the histamine and methacholine challenges in the diagnosis of cryptic shortness of breath. Third, the differential sensitivity of various bronchoconstrictor indices in both normal and asthmatic subjects when leukotrienes are used may provide clues as to the locus of airway hyperresponsiveness in asthma. Thus, leukotrienes hold the promise of new ways to treat and diagnose asthma, as well as providing new insights into the pathobiology of the disease itself.
Drazen, J. M., I. Dreshaij, et al. (1986). "CO2 elimination by high-frequency oscillation: effects of vagosympathetic stimulation." J Appl Physiol 61(5): 1836-42.
The effects of electrical stimulation of the vagi on gas transport mediated by high-frequency, low tidal volume ventilation (HFV) was examined in 10 anesthetized, paralyzed, propranolol-treated dogs. Gas transport efficiency was estimated by measuring the rate of CO2 removed from the lungs (Vco2) achieved during 45-s bursts of HFV applied before (control 1), during, and after (control 2) electrical stimulation of the transected vagi. During vagal stimulation the heart rate was maintained by electrical pacing. During the 15-s phase of vagal stimulation pulmonary impedance increased from 3.6 +/- 0.7 to 6.2 +/- 2.2 cmH2O X l-1 X s, and Vco2 increased. When the electrical stimulation of the vagi was stopped, impedance and Vco2 returned to prestimulation values. Vco2 was always higher during electrical stimulation of the vagi when HFV of a fixed volume was applied over a range of frequencies or when a fixed oscillation frequency was used over a range of tidal volumes. The effects of vagal stimulation on HFV-mediated gas transport were quite similar to the effects of moving the locations of the bias flow inlet and outlet into the lung such that tracheal volume was decreased by 20 ml, an amount equivalent to estimated change in control airway volume thought to occur during vagal stimulation. We simulated the effects of vagal stimulation and decreased tracheal volume on Vco2 by using a previously described model of HFV-mediated gas transport.(ABSTRACT TRUNCATED AT 250 WORDS)
Davidson, A. B., J. Seltzer, et al. (1986). "Effect of tidal volume and anesthetic agent on airway responsiveness to histamine." J Appl Physiol 60(5): 1765-71.
Dose-response relationships for bronchoconstriction in response to aerosal histamine were assessed before and after vagotomy in 11 dogs anesthetized with barbiturates and in 9 dogs anesthetized with alpha-chloralose-urethan. The dose-response relationships following vagotomy were assessed during spontaneous ventilation and during muscular paralysis and mechanical ventilation with tidal volume (VT) similar to each animal's VT prior to vagotomy. After vagotomy the spontaneous VT of both groups increased but the VT of the alpha-chloralose-urethan group was significantly less than that of the barbiturate group. The histamine responsiveness of the animals anesthetized with barbiturates was significantly greater during mechanical ventilation when VT was reduced to prevagotomy levels compared with during spontaneous ventilation. In contrast, the histamine responsiveness of the alpha-chloralose-urethan group was not significantly changed by reducing VT to prevagotomy levels. In six other dogs anesthetized with pentobarbital sodium and studied after vagotomy, responsiveness to histamine aerosol during controlled ventilation with breaths of prevagotomy VT was greater than responsiveness during mechanical ventilation with large volume breaths given immediately afterward. Thus the magnitude of VT of dogs after vagotomy may influence airway responsiveness, and the influence of anesthetic agents on airway responsiveness after vagotomy may in part be due to their effects on VT. Furthermore, bronchodilation accompanying large volume ventilation persists after vagotomy, suggesting that it is not exclusively mediated by changes in parasympathetic activity.
Castile, R. G., O. F. Pedersen, et al. (1986). "Density dependence of maximal expiratory flow before and during tracheal constriction in dogs." J Appl Physiol 60(3): 1060-6.
The effect of carbachol-induced central bronchoconstriction on density dependence of maximal expiratory flow (MEF) was assessed in five dogs. MEFs were measured on air and an 80% He-20% O2 mixture before and after local application of carbachol to the trachea. Airway pressures were measured using a pitot-static probe, from which central airway areas were estimated. At lower concentrations of carbachol the flow-limiting site remained in the trachea over most of the vital capacity (VC), and tracheal area and compliance decreased in all five dogs. In four dogs, decreases in choke point area predominated and produced decreases in flows. In one dog the increase in airway "stiffness" apparently offset the fall in area to account for an increase in MEF. Density dependence measured as the ratio of MEF on HeO2 to MEF on air at 50% of VC increased in all five dogs. Increases in density dependence appeared to be related to increases in airway stiffness at the choke point rather than decreases in gas-related airway pressure differences. Lower concentrations produced a localized decrease in tracheal area and extended the plateau of the flow-volume curve to lower lung volumes. Higher concentrations caused further reductions in tracheal area and greater longitudinal extension of bronchoconstriction, resulting in upstream movement of the site of flow limitation at higher lung volumes. Density dependence increased if the flow-limiting sites remained in the trachea at mid-VC but fell if the flow-limiting site had moved upstream by that volume.
Berdine, G. G., J. L. Lehr, et al. (1986). "Nonuniformity of canine lung washout by high-frequency ventilation." J Appl Physiol 61(4): 1388-94.
Ethane washout during low tidal volume (25-100 ml) high-frequency (3-40 Hz) ventilation (HFV) was studied in seven excised dog lungs. The lungs were initially equilibrated with 1% ethane, and then the concentration of ethane was monitored by mass spectrometry from multiple anatomic sites along the tracheobronchial tree during washout. We observed that the lung changed from a uniform distribution of ethane concentrations to a nonuniform distribution by a three-phase process. The first phase was nearly complete within the first 15 s and probably corresponds to concentration gradients being established in the central airways. During the second phase of washout, which lasted for several minutes, the concentrations in the various alveolar regions diverged. In the final phase, the regional concentrations remained at fixed ratios, and washout from all sites in the lung was at a constant fractional rate. These data are consistent with a model in which the duration of the second phase and the magnitude of the regional concentration differences established in this phase are dependent on both the magnitude of differences between regional transport paths and the nature of regional coupling by a common transport path to the airway opening.
Solway, J., N. Gavriely, et al. (1985). "Effect of bias flow rate on gas transport during high-frequency oscillatory ventilation." Respir Physiol 60(2): 267-76.
Ventilatory support with low tidal volume, high-frequency oscillatory ventilation (HFOV) usually uses a bias flow system to provide fresh gas. Although the bias flow rates (Vbf) used previously have varied widely among experimental configurations, the precise role of the bias flow in HFOV-mediated gas transport has not been defined. We assessed the effect of bias flow rate on gas transport during HFOV by measuring CO2 removal rate (MCO2) in anesthetized, paralyzed dogs, using a wide range of bias flow rates (0.7-28.9 L X min-1). When a fixed tidal volume of 40 ml was applied at HFOV frequencies of 2-12 Hz, MCO2 was proportional to the time-averaged alveolar-bias flow CO2 concentration difference. Thus, when Vbf was reduced below a value which resulted in a substantial increase in bias flow CO2 concentration, MCO2 was reduced. These findings are consistent with a simple framework in which the relative magnitudes of the resistances to gas transport of the airways and of the bias flow (1/Vbf) determine the contribution of the bias flow rate to overall gas transport during HFOV. This relationship may be employed to assess the intra-airway contribution to HFOV-mediated gas transport at any bias flow rate, and may therefore allow comparison of results from experiments utilizing various bias flow rates.
Solway, J., B. M. Pichurko, et al. (1985). "Breathing pattern affects airway wall temperature during cold air hyperpnea in humans." Am Rev Respir Dis 132(4): 853-7.
We studied the influence of flow rate on respiratory heat exchange in 9 healthy adult subjects using a new noninvasive technique, the single-breath temperature washout (SBTW) curve. The SBTW curve is a plot of exhaled gas temperature versus exhaled volume during a standard exhalation and consists of an initial rise (within the first 200 ml) to a plateau temperature that persists through the remainder of exhalation. We found that exhaled gas temperatures within the initial expirate were colder at every airway locus than corresponding intra-airway gas temperatures at end-inspiration, suggesting that heat exchange occurs between lumenal gas and the relatively cooler airway walls during exhalation. The SBTW plateau temperatures were: (1) lower after preconditioning the airways with rapid (80 L/min) isocapnic hyperpnea of frigid air than after less rapid (40 L/min) cold-air hyperpnea or after quiet breathing; (2) lower when, after identical airway preconditioning regimens, the SBTW exhalation was performed with a slower (0.5 versus 2.5 L/s) expiratory flow; and (3) lower when SBTW curves were obtained after airway preconditioning using respiratory patterns with larger inspiration-expiration duration (I:E) ratios (5:1 versus 1:5) at fixed minute ventilation and respiratory rate. Our results indicate that the global respiratory gas-wall heat transfer coefficient increases with velocity to the 0.9 power, a finding similar to that in previous studies of turbulent flow in rigid pipes.
Lehr, J. L., J. P. Butler, et al. (1985). "Photographic measurement of pleural surface motion during lung oscillation." J Appl Physiol 59(2): 623-33.
The regional pleural surface expansion of an excised dog lung was measured during high-frequency ventilation (HFV) using synchronized stroboscopic photography to stop lung motion at 20 evenly spaced intervals over a respiratory cycle during ventilation at 1 Hz with a volume of 100 ml, 15 Hz with 100 ml, or 30 Hz with 50 ml. The lungs were also photographed during quasi-static deflation. The pleural surface was marked with ink dots to form 84 approximately square figures. The side lengths and areas of each of the 84 "squares" were measured for each frame of each photo sequence. At 1 Hz and during the quasi-static deflation the lung ventilated nearly synchronously, although minor nonuniformities were noted on both small and large length scales. At 15 and 30 Hz, the lung expanded asynchronously and nonuniformly, with a 78% increase in surface expansion per 100 ml of tracheal tidal volume, as frequency was increased from 1 to 30 Hz. These nonuniformities in expansion suggest marked interregional airflow and elastic wave propagation in the parenchyma during HFV.
Lee, T. H., J. M. Drazen, et al. (1985). "Substrate and regulatory functions of eicosapentaenoic and docosahexaenoic acids for the 5-lipoxygenase pathway. Implications for pulmonary responses." Prog Biochem Pharmacol 20: 1-17.
Lee, T. H., K. F. Austen, et al. (1985). "The effects of a fish-oil-enriched diet on pulmonary mechanics during anaphylaxis." Am Rev Respir Dis 132(6): 1204-9.
The pulmonary mechanical responses observed after antigen challenge in 2 groups of sensitized, mepyramine-treated, mechanically ventilated guinea pigs were compared: one group was fed a diet rich in fish oil and the other a control diet enriched with beef tallow. The lung tissue of animals fed a fish-oil-enriched diet for 9 to 10 wk incorporated eicosapentaenoic acid (EPA) and docosahexaenoic acid, which constituted 8 to 9% of the total fatty acid content, whereas these alternative fatty acids constituted less than 1% of total fatty acid content of the lung tissue of animals receiving a diet supplemented with beef tallow. With mepyramine pretreatment, animals receiving a fish oil diet exhibited a significantly greater decrease in dynamic compliance from 1.5 through 4.5 min after antigen challenge than did animals receiving a beef fat diet, whereas the decrements in pulmonary conductance were comparable. The combination of indomethacin and mepyramine markedly augmented the antigen-induced decrease in pulmonary mechanics in animals receiving a beef fat diet but not in those receiving a fish oil diet, such that the overall responses of the 2 groups were similar. These findings indicate that the fish oil diet and the indomethacin pretreatment of animals receiving the beef fat diet each facilitates the nonhistamine-mediated bronchoconstrictor response in pulmonary anaphylaxis.
Israel, E., S. Shore, et al. (1985). "Leukotrienes and immediate hypersensitivity responses." Ann Inst Pasteur Immunol 136D(2): 216-9.
Gavriely, N., J. Solway, et al. (1985). "Radiographic visualization of airway wall movement during oscillatory flow in dogs." J Appl Physiol 58(2): 645-52.
It has been suggested that radial movement of the central airway walls during oscillatory flow might contribute to the increased frequency dependence of compliance seen in chronic obstructive pulmonary disease (COPD) (J. Appl. Physiol. 26: 670-677, 1969). Radial airway wall motion has also been invoked to explain the frequency-dependent decreases in the efficiency of gas exchange during low-volume high-frequency ventilation (HFV) in histamine-bronchoconstricted dogs and in patients with respiratory insufficiency. To test the possibility that airway wall motion increases with bronchoconstriction, we measured central airway diameters using cinebronchoradiography in anesthetized tracheostomized dogs during oscillatory HFV [50 and 100 ml tidal volume (VT) at frequencies (f) of 2, 6, and 12 Hz], under control conditions, during electrical stimulation of the vagi, and after exposure to histamine aerosol. Cineradiobronchograms from two dogs were evaluated quantitatively for tracheal diameter and for lengths and diameters of a number of major airways. Under control conditions, the diameter of the airways fluctuated 7-9% of the mean with VT of 50 ml and 9-18% with VT of 100 ml in the range of frequencies studied. Bronchoconstriction produced by aerosolized histamine increased radial airway wall movement to 10-47% with VT of 50 ml, and during vagal stimulation diameters changed 7-20% at VT of 50 ml. After histamine, the central airways displayed large diameter changes during HFV, whereas more peripheral airways were markedly constricted and did not change in diameter.(ABSTRACT TRUNCATED AT 250 WORDS)
Gavriely, N., J. Solway, et al. (1985). "Pressure-flow relationships of endotracheal tubes during high-frequency ventilation." J Appl Physiol 59(1): 3-11.
We studied the pressure-flow relationships of various endotracheal tubes (ETT) at frequencies (f) and tidal volumes (VT) in the range used for high-frequency ventilation (HFV) (f: 2-32 Hz, VT: 15-100 ml). Sinusoidal flows were applied to ETT inserted into a rigid bottle or into the tracheae of three anesthetized paralyzed dogs, while pressure fluctuations were measured both proximal and distal to the ETT. The pressure drops in the ETT were nonlinearly related to the peak flow rate and were VT dependent, suggesting that turbulent frictional head loss and convective acceleration were important. The pressure drops measured in vitro were found to be in good agreement with the predictions of a nonlinear oscillatory pressure-flow equation (derived herein), which incorporate the effects of turbulent frictional losses, convective acceleration, inertance, and compliance. The pressure drops measured in situ were 30-50% higher than with the corresponding f-VT combinations in vitro. Possible explanations of these differences are junctional losses at the tip of the ETT or the nonrigid character of the trachea.
Fredberg, J. J., R. H. Ingram, Jr., et al. (1985). "Nonhomogeneity of lung response to inhaled histamine assessed with alveolar capsules." J Appl Physiol 58(6): 1914-22.
To assess the homogeneity of airway responses to inhaled histamine we examined regional alveolar pressure excursions (PA) arising from small-amplitude oscillations applied at the airway opening (Pao). In five anesthetized and vagotomized dogs the sternum was split and the anterior right lung field exposed. PA was sampled using four capsules affixed to the right apical and middle lobes while lung impedance (ZL) and airway impedances (Zaw) were measured during conventional tidal breathing and during forced oscillations (2-60 HZ at 10 cmH2O distending pressure). During tidal breathing after exposure to aerosol histamine regional PA's could be separated into three groups by plotting Lissajous figures of PA vs. Pao: PA in phase with Pao (no looping), PA lagging Pao (moderate looping), and PA decreasing while Pao was increasing and vice versa (paradoxical looping), suggesting unresponsive, responsive, and closed pathways, respectively, between the airway opening and specific alveolar zones. During high-frequency oscillation the corresponding PA spectra were markedly different from control spectra and revealed resonant amplification, overdamped resonance, and marked attenuation, respectively. With induced bronchospasm resonant amplification of PA was damped on average. However, the more obstructed and closed pathways were protected from resonant amplification, and the more open (nonlooping) pathways were subjected to resonant amplification greater than in the control state. In spite of this markedly nonhomogeneous behavior, frequency dependence of ZL was consistent with the model by Mead (J. Appl. Physiol. 26: 670-673, 1969), which ignores nonhomogeneity of peripheral compartments. These data demonstrate that the response of airways to inhaled histamine is nonhomogeneous but that frequency dependence of ZL above 2 Hz is not sufficient to characterize this nonhomogeneity.
Bhaskar, K. R., D. D. O'Sullivan, et al. (1985). "Density gradient study of bronchial mucus aspirates from healthy volunteers (smokers and nonsmokers) and from patients with tracheostomy." Exp Lung Res 9(3-4): 289-308.
Because it is difficult to obtain, little is known of bronchial mucus from the normal human airway; it has been mainly studied as sputum expectorated in chronic bronchitis with particular attention to epithelial glycoprotein. We have now applied density gradient methods to study this and other macromolecules and lipids in normal airway mucus. After lavage at bronchoscopy, mucus was aspirated from six normal volunteers, that include one light and two heavy smokers. This normal mucus has been compared with that obtained from four patients with tracheostomy because of respiratory muscle paralysis due to neurological disease. The normal aspirates contained small threads of mucus, the tracheostomy aspirates viscous blobs of jelly, a difference in physical appearance reflected in macromolecular yields, 0.3-1 mg/ml and 6-24 mg/ml respectively. On analytical ultracentrifugation normal mucus showed no discernible material in the buoyant density region typical of epithelial glycoprotein (1.5 g/ml): Virtually all the material migrated to the miniscus and was predominantly lipids and proteins. A trace amount of material recovered from a higher density region (greater than or equal to 1.6 g/ml) was found to contain both glycoprotein and proteoglycan. Aspirates from the heavy smokers contained appreciable amounts of material with typical buoyant density (approximately 1.5 g/ml) but still with features of proteoglycan. In contrast in tracheostomy aspirates epithelial glycoprotein of typical buoyant density and chemical composition accounted for up to 25% of nondialyzable material. We conclude that under normal conditions typical epithelial glycoprotein is virtually absent from airway mucus and that the glycoconjugate present has features of glycoprotein and proteoglycan.
Venugopalan, C. S., S. I. Said, et al. (1984). "Effect of vasoactive intestinal peptide on vagally mediated tracheal pouch relaxation." Respir Physiol 56(2): 205-16.
Vasoactive intestinal peptide (VIP) was studied as a possible neurotransmitter of nonadrenergic inhibition in guinea pig tracheas in vivo, by examining the effects of VIP and isoproterenol on pressure changes induced by nerve stimulation in an isolated, fluid filled, tracheal segment (tracheal pouch). VIP though less potent than isoproterenol produced a dose-dependent relaxation of the pouch. Incubation of the histamine-constricted tracheal pouch with isoproterenol resulted in pouch relaxation and a significant (P less than 0.005) loss of pouch responsiveness to sympathetic nerve stimulation, while non-adrenergically mediated pouch relaxation resulting from vagal stimulation in the presence of atropine was inhibited to a much smaller degree. VIP incubation produced relaxation of the histamine-constricted pouch and resulted in a greater loss of responsiveness to vagal than to sympathetic stimulation (P less than 0.02). By demonstrating loss of vagal responsiveness after VIP in guinea pigs, sympathectomized by 6-hydroxydopamine combined with incubation of the pouch with propranolol to eliminate circulating beta adrenergic inhibition, the effects of VIP incubation on vagally induced pouch relaxation were confirmed to be non-adrenergic in nature.
Solway, J., N. Gavriely, et al. (1984). "Intra-airway gas mixing during high-frequency ventilation." J Appl Physiol 56(2): 343-54.
We examined the intra-airway gas transport mediated by high-frequency oscillations (HFO) in 10 nonintubated healthy volunteers using a method based on comparisons of single-breath N2-washout curves obtained after various durations of breath hold or high-frequency oscillations. With a mathematical analysis based on Fick's law of diffusion we computed the local transport parameter, effective diffusivity, during oscillations of frequency 2-24 Hz and tidal volume 10-120 ml and during breath hold alone. Local effective diffusivity increased with both oscillatory frequency and tidal volume at all levels in the tracheobronchial tree; the enhancing effect of tidal volume on local effective diffusivity was more pronounced than that of frequency so that effective diffusivity was greater with larger tidal volume at fixed frequency-tidal volume product (f . VT). The greatest enhancement of gas mixing within the lung during HFO (over breath hold) was seen in the central airways. In previous studies examining CO2 removal rate during HFO (J. Clin. Invest. 68: 1475, 1981), we found that CO2 output was also greater with larger tidal volume at fixed f . VT, and we attributed this to an end constraint imposed by a fresh gas bias flow. Results of the current study, performed without a bias flow, indicate that bias flow end constraint does not solely account for the observed dependence of CO2 output on frequency and tidal volume.
Seltzer, J., P. D. Scanlon, et al. (1984). "Morphologic correlation of physiologic changes caused by SO2-induced bronchitis in dogs. The role of inflammation." Am Rev Respir Dis 129(5): 790-7.
Chronic bronchitis was induced in 6 mongrel dogs by exposure to SO2 gas for 6 to 18 months. All of the dogs developed cough and mucus hypersecretion. Chronic airway obstruction and decreased airway responsiveness to inhaled histamine developed in 5 of the dogs. Histologic changes in dogs evaluated after SO2 exposure included significant mucous gland hypertrophy and hyperplasia, epithelial thickening, and a decrease in the number of luminal cells containing undischarged secretory granules. Acute and chronic inflammation were found in the dogs with airway obstruction and decreased responsiveness to histamine, but such inflammation was absent in the one dog that failed to develop physiologic changes. After a period of recovery from SO2 exposure of 9 to 21 months, inflammation regressed dramatically and the other histologic changes returned toward normal. Physiologic changes regressed somewhat in those dogs that had had changes. These findings suggest that inflammation may be an important factor influencing the development of airway obstruction and altered airway responsiveness in the setting of chronic bronchitis.
Saari, A. F., T. H. Rossing, et al. (1984). "Physiological bases for new approaches to mechanical ventilation." Annu Rev Med 35: 165-74.
High frequency ventilatory (HFV) techniques offer potential advantages over conventional forms of mechanical ventilation in patients with diverse forms of respiratory insufficiency. In some respects, HFV challenges conventional physiologic concepts regarding gas transport in the lung. We review hypotheses regarding the mechanism of gas transport and provide a brief perspective on current clinical applications of these techniques.
Saari, A. F., T. H. Rossing, et al. (1984). "Lung inflation during high-frequency ventilation." Am Rev Respir Dis 129(2): 333-6.
We investigated the relationship between mean airway pressure and lung volume during low-tidal-volume, high-frequency ventilation (HFV). Eight patients requiring mechanical ventilatory support for treatment of respiratory insufficiency were studied by imposing rapid (60 to 600 breaths/min) oscillations with low tidal volumes (50 to 150 ml) at a constant mean airway pressure of 5 cm H2O. Despite this constant mean airway pressure, lung volume increased substantially during the oscillation period in 7 of 8 subjects, as indicated both by an increase in thoracoabdominal dimensions and by an increase in respiratory system relaxation pressures after the oscillations were stopped. For each patient in whom these changes occurred, the degree of lung inflation rose progressively with increases in either frequency or tidal volume. Given this dissociation between lung volume and mean airway pressure, some index of lung volume or alveolar pressure should be monitored to minimize the likelihood of adverse effects during HFV.
Rossing, T. H., J. Solway, et al. (1984). "Influence of the endotracheal tube on CO2 transport during high-frequency ventilation." Am Rev Respir Dis 129(1): 54-7.
Low-volume, high-frequency ventilation (HFV) delivered via an endotracheal tube can maintain eucapnia in both humans and animals. Because recent animal studies have suggested that a substantial fraction of the resistance to gas transport during HFV can be attributed to the presence of the endotracheal tube, we evaluated the importance of the endotracheal tube on carbon dioxide elimination (VCO2) during HFV in humans. We compared the effectiveness of delivering the fresh gas bias flow at the proximal and the distal end of an endotracheal tube. For each bias flow position, we ventilated patients using tidal volumes of 60 ml or less and frequencies from 0.5 to 12 Hz. In each case, VCO2 was approximately 50% greater when the fresh gas was introduced at the carinal end of the endotracheal tube. Thus, the endotracheal tube contributed about one third of the resistance to HFV-induced CO2 transport in these patients. These results indicate that the position of the fresh gas source strongly influences the effectiveness of HFV.
Leitch, A. G., T. H. Lee, et al. (1984). "Immunologically induced generation of tetraene and pentaene leukotrienes in the peritoneal cavities of menhaden-fed rats." J Immunol 132(5): 2559-65.
The generation of sulfidopeptide leukotrienes and leukotriene B (LTB) in response to an IgG-mediated immune complex reaction in the peritoneal cavities of rats fed either a menhaden oil-supplemented diet or a beef tallow-supplemented diet for 9 to 10 wk was determined with the combined techniques of radioimmunoassay (RIA) and reverse-phase high performance liquid chromatography. Rats on the fish fat diet (FFD) incorporated eicosapentaenoic acid (EPA) into pulmonary and splenic tissues with an EPA:arachidonic acid ratio of approximately 2:1, whereas rats on the beef fat diet (BFD) showed no detectable EPA. The estimated total quantities of immunoreactive sulfidopeptide leukotrienes generated by each group of rats were similar, ranging from 70 to 99 ng/ rat in the FFD groups and 65 to 109 ng/rat in the BFD groups; for rats on the FFD this total included the pentaene products LTC5, LTD5, and LTE5 in quantities ranging from 24 to 39 ng/rat. The total quantities of immunoreactive LTB generated in the two groups of rats were similar, being 6 to 29 ng LTB4/rat for the BFD groups and the sum of LTB4 and LTB5 of 8 to 36 ng/rat for the FFD groups. There was a two- to seven-fold preferential generation of immunoreactive LTB5 over LTB4 in the FFD rats. LTC5 was equipotent with LTC4 in contracting guinea pig pulmonary parenchymal strips and ileal tissues. In contrast, LTB5 was 1/30 to 1/60 as potent and did not reach the same maximum as LTB4 in eliciting neutrophil chemotaxis. The finding that FFD favors the immunologic generation of LTB5, which has attenuated biologic activity when compared to LTB4, suggests that EPA-enriched tissues may produce less pro-inflammatory activity than tissues that are EPA-poor.
Lee, T. H., K. F. Austen, et al. (1984). "Leukotriene E4-induced airway hyperresponsiveness of guinea pig tracheal smooth muscle to histamine and evidence for three separate sulfidopeptide leukotriene receptors." Proc Natl Acad Sci U S A 81(15): 4922-5.
Bronchial hyperresponsiveness to contractile agonists and nonspecific irritants is a characteristic feature of bronchial asthma. The mechanisms causing this hyperirritability are unknown. The existence of separate receptors for leukotrienes C4 and D4 (LTC4 and LTD4) has been demonstrated previously by physiologic and radioligand binding studies. The rank order of potency of the sulfidopeptide leukotrienes for contracting tracheal spirals [leukotriene E4 (LTE4) greater than LTD4 = LTC4] is different from that for contracting parenchymal strips (LTD4 greater than LTE4 greater than LTC4), thereby suggesting the existence of a separate receptor for LTE4. We now report that LTE4, the most stable of the leukotrienes comprising slow reacting substance of anaphylaxis, enhances the contractile response of guinea pig tracheal spirals but not of parenchymal strips to histamine in a time- and dose-dependent fashion. The ability of LTE4 to increase histamine responsiveness occurred after removal of the free agonist and recovery of the tissues to baseline tensions and was not produced by leukotrienes C4 and D4, which elicited the same magnitude of contraction of tracheal smooth muscle as LTE4. These findings suggest that LTE4-induced airway hyperirritability is not mediated by the contractile response per se and may be mediated through a receptor distinct from those for leukotrienes C4 and D4.
Khoo, M. C., A. S. Slutsky, et al. (1984). "Gas mixing during high-frequency ventilation: an improved model." J Appl Physiol 57(2): 493-506.
A model for gas transport during high-frequency ventilation incorporating recently derived empirical forms for the effective diffusivity in oscillatory gas flow through a symmetrical branching network is proposed. The model accounts for the movement of gas among airways with changing cross-sectional area by using a moving-reference-frame analysis. The analysis technique incorporates the convective purging of the bias flow at the airway opening. The model predicts that although the cycle-averaged CO2 elimination rate (VCO2) depends most strongly on the product of frequency and tidal volume (VT), VT has an effect on its own, a finding consistent with published observations. This "VT effect" is due primarily to the oscillatory movement of gas from more central regions into peripheral regions where large cross-sectional areas promote efficient CO2 transport by molecular diffusion. Although the VT effect exists independent of the presence of a bias flow, placing the bias flow near the main carina can enhance the VT effect substantially. As VT is increased to values in the range of ordinary tidal breaths, VCO2 predicted by the model achieves close agreement with VCO2 deduced from conventional gas exchange theory.
Kamm, R. D., A. S. Stutsky, et al. (1984). "High-frequency ventilation." Crit Rev Biomed Eng 9(4): 347-79.
Recent experiments have demonstrated that normal pulmonary gas exchange rates can be achieved in humans and test animals using high frequency (1 to 30 Hz), low volume (comparable to, or less than the dead space volume) oscillations imposed at the mouth or through an endotracheal tube. This review examines the different methods of High Frequency Ventilation (HFV) and the mechanisms thought to be responsible for gas transport, which are intrinsically different than in normal tidal breathing. Several potentially important transport mechanisms are discussed, including augmented dispersion, bidirectional streaming due to asymmetric velocity profiles, direct ventilation of near alveoli, and intercompartmental mixing or pendelluft. Models used to predict the rate of gas exchange in HFV are described in terms of their theoretical and experimental bases. The model predictions are compared to results of physiologic experiments.
Gordon, T., C. S. Venugopalan, et al. (1984). "Ozone-induced airway hyperreactivity in the guinea pig." J Appl Physiol 57(4): 1034-8.
The predominant airway site and mechanism underlying ozone (O3)-induced respiratory hyperresponsiveness was examined in anesthetized guinea pigs and in vitro tissue preparations. Animals exposed to 1.0 or 1.2 ppm O3 (1 h) demonstrated an enhanced airway response to subcutaneous histamine compared with air-exposed animals. The anatomic site of hyperresponsiveness most likely did not involve the parenchyma, since quasi-static deflationary pulmonary compliance was decreased to a similar extent by histamine in air- and O3-preexposed animals. In contrast, the conducting airways were probably involved as changes in pulmonary resistance elicited by subcutaneous histamine were greater in O3- than in air-exposed animals. Neither atropine nor vagotomy abolished this enhanced responsiveness induced by O3. Although vagal interruption did not alter responsiveness, O3-exposed animals demonstrated greater respiratory responses to efferent electrical stimulation of the vagi than air-exposed animals. This suggests the site of hyperresponsiveness may be located distal to the site of efferent stimulation, possibly in the smooth muscle itself or in its microenvironment.
Drazen, J. M., R. D. Kamm, et al. (1984). "High-frequency ventilation." Physiol Rev 64(2): 505-43.
Complete physiological understanding of HFV requires knowledge of four general classes of information: 1) the distribution of airflow within the lung over a wide range of frequencies and VT (sect. IVA), 2) an understanding of the basic mechanisms whereby the local airflows lead to gas transport (sect. IVB), 3) a computational or theoretical model in which transport mechanisms are cast in such a form that they can be used to predict overall gas transport rates (sect. IVC), and 4) an experimental data base (sect. VI) that can be compared to model predictions. When compared with available experimental data, it becomes clear that none of the proposed models adequately describes all the experimental findings. Although the model of Kamm et al. is the only one capable of simulating the transition from small to large VT (as compared to dead-space volume), it fails to predict the gas transport observed experimentally with VT less than equipment dead space. The Fredberg model is not capable of predicting the observed tendency for VT to be a more important determinant of gas exchange than is frequency. The remaining models predict a greater influence of VT than frequency on gas transport (consistent with experimental observations) but in their current form cannot simulate the additional gas exchange associated with VT in excess of the dead-space volume nor the decreased efficacy of HFV above certain critical frequencies observed in both animals and humans. Thus all of these models are probably inadequate in detail. One important aspect of these various models is that some are based on transport experiments done in appropriately scaled physical models, whereas others are entirely theoretical. The experimental models are probably most useful in the prediction of pulmonary gas transport rates, whereas the physical models are of greater value in identifying the specific transport mechanism(s) responsible for gas exchange. However, both classes require a knowledge of the factors governing the distribution of airflow under the circumstances of study as well as requiring detail about lung anatomy and airway physical properties. Only when such factors are fully understood and incorporated into a general description of gas exchange by HFV will it be possible to predict or explain all experimental or clinical findings.
Drazen, J. M. (1984). "Physiological basis and interpretation of indices of pulmonary mechanics." Environ Health Perspect 56: 3-9.
Tests of pulmonary mechanical function provide information about the state of the lungs, both airways and parenchyma. This information can be extracted from measurements made in experimental animals, especially the combined determination of pulmonary resistance and dynamic compliance. This report discusses the rationale upon which effects of an intervention on the lung periphery can be distinguished from those on more central airways. Further, practical considerations involved in making these measurements are discussed.
Weiss, J. W., J. M. Drazen, et al. (1983). "Airway constriction in normal humans produced by inhalation of leukotriene D. Potency, time course, and effect of aspirin therapy." Jama 249(20): 2814-7.
Five normal human subjects inhaled aerosols generated from solutions of leukotriene D (LTD) to determine the bronchoconstrictor potency and the time course of airway obstruction produced by this constituent of slow-reacting substance of anaphylaxis. The dose-effect and time-effect curves were compared with curves similarly generated for the well-characterized airway constrictor histamine. Leukotriene D was, on average, 5,900 times more potent than histamine on a molar basis in producing an identical decrement in maximal expiratory flow rate at 30% of control vital capacity above residual volume. In addition, although LTD had a rapid onset of effect, similar to that of histamine, the airway obstruction produced by LTD was longer lasting, thereby reflecting more closely the response of asthmatic allergic individuals to antigen inhalation. The response of these subjects to inhalation of LTD was not altered by ingestion of aspirin, suggesting that the airway obstruction was not mediated by cyclooxygenase products of arachidonic acid.
Slutsky, A. S., R. D. Kamm, et al. (1983). "High frequency oscillatory ventilation using tidal volumes smaller than the anatomical dead space." Int Anesthesiol Clin 21(3): 161-81.
Lewis, R. A., C. W. Lee, et al. (1983). "Biology of the C-6-sulfidopeptide leukotrienes." Adv Prostaglandin Thromboxane Leukot Res 11: 15-26.
Leitch, A. G., K. F. Austen, et al. (1983). "Effects of indomethacin on the guinea-pig pulmonary response to intravenous leukotrienes C4 and D4." Clin Sci (Lond) 65(3): 281-7.
We measured pulmonary conductance (GL), dynamic compliance (Cdyn.), and arterial pressure in chloralose-urethane anaesthetized guinea pigs for 30 min after intravenous infusion of either leukotriene (LT) C4 (1 microgram/kg) or LTD4 (0.5 microgram/kg) to control or indomethacin-pretreated (30 mg/kg) animals. LT infusion to control animals caused decrements in GL, which were maximal at 30 s and persisted for 7.5 min (LTD4) and 15 min (LTC4), decrements in Cdyn., which were maximal at 30 s and persisted for 30 min, and hypotension. Indomethacin treatment before LT infusion significantly altered the changes in GL by reducing the early (less than 1 min) response and potentiating the later (3-5 min) response, significantly reduced the fall in Cdyn. at all time points, resulting in a change in the GL/Cdyn. ratio to 1.0 and prolonged the hypotensive response. We conclude that cyclo-oxygenase products are responsible for the early (less than 1 min) pulmonary response to LT infusion and modulate the later (3-5 min) response but do not cause hypotension. With cyclo-oxygenase inhibition, the significant primary activity of LT is possibly less preferentially directed to contractile tissues associated with small airways.
Leitch, A. G., E. J. Corey, et al. (1983). "Indomethacin potentiates the pulmonary response to aerosol leukotriene C4 in the guinea pig." Am Rev Respir Dis 128(4): 639-43.
Aerosol administration of leukotriene (LT) C4 to anesthetized, mechanically ventilated guinea pigs results in significant dose-dependent decrements in dynamic compliance (Cdyn) and pulmonary conductance (GL) when the concentration of LTC4 in the nebulizer is in the range of 0.5 to 5 micrograms/ml. Pretreatment with indomethacin, 30 mg/kg given intraperitoneally, significantly potentiates the decrements in Cdyn and GL elicited by aerosol LTC4 at 1 microgram/ml. Potentiation of the pulmonary response is seen even with an aerosol LTC4 concentration of 0.3 micrograms/ml, which alone produces only minimal changes in pulmonary mechanics in control animals. These findings suggest that bronchodilator prostaglandins are important inhibitory modulators of this pulmonary response and that secondary thromboxane release probably does not contribute to the response to inhaled LTC4. The effect of indomethacin pretreatment in augmenting the pulmonary response to aerosol LTC4 in the guinea pig may have relevance for the phenomenon of asthma induced in humans by ingestion of nonsteroidal anti-inflammatory agents.
Griffin, M., J. W. Weiss, et al. (1983). "Effects of leukotriene D on the airways in asthma." N Engl J Med 308(8): 436-9.
Fanta, C. H. and J. M. Drazen (1983). "Calcium blockers and bronchoconstriction." Am Rev Respir Dis 127(6): 673-4.
Drazen, J. M., C. H. Fanta, et al. (1983). "Effect of nifedipine on constriction of human tracheal strips in vitro." Br J Pharmacol 78(4): 687-91.
1 Autopsy specimens of human trachealis muscle were used to investigate the effect of the calcium channel blocker, nifedipine, on airway smooth muscle constriction. With these tracheal strips, two consecutive cumulative concentration-effect curves to histamine (0.1-100 microM) obtained at a 60 min interval were highly reproducible. 2 We examined the effects of adding nifedipine (2.9 microM) to the incubation medium before the second histamine response. The concentration-effect relationships determined after nifedipine incubation were significantly different from control: the response to 100 microM histamine was reduced by approximately one-half (to 2.53 +/- 0.6 g; P less than 0.025), and the concentration of histamine causing 40% of the maximal control contraction (EC40) increased nearly ten fold (to 36.9 +/- 10.5 microM; P less than 0.02). 3 In two additional tracheal strips submaximally constricted with 10 microM histamine, nifedipine 2.9 microM caused complete relaxation to resting tension or below. 4 These results indicate a direct inhibitory effect of nifedipine on airway smooth muscle constriction and partial dependence of human trachealis muscle on calcium ion fluxes for initiation and maintenance of contraction. In addition, the results suggest a potential mechanism for the inhibitory effects of calcium channel blocking drugs in exercise-induced asthma.
Drazen, J. M., P. G. Lacouture, et al. (1983). "Inhibition by propranolol of the contractile response of the rat diaphragm to tetanic field stimulation in vitro." Br J Pharmacol 80(4): 613-8.
Contraction of the rat isolated diaphragm in response to maximal tetanic stimulation was examined before and after isoprenaline or propranolol. Isoprenaline (10(-4)M) did not affect maximum isometric force, whereas propranolol depressed maximum force in a concentration-dependent manner (10(-6)-10(-4)M). Inhibition due to propranolol (10(-4)M) could not be overcome by increasing the intensity or duration of electrical stimulation, and was only partially reversed (mean 73% +/- 10 s.e. mean) after washing. Pretreatment with isoprenaline did not alter the response of the muscle to propranolol, nor did neuromuscular blockade with (+)-tubocurarine. The response to either stereoisomer of propranolol was similar to that obtained with the racemate. Atenolol, a beta-adrenoceptor blocking agent without membrane stabilizing activity, had minimal (less than 10%) depressant effects on diaphragmatic force development. Lignocaine (8.5 X 10(-6)-8.5 X 10(-5)M) produced a concentration-related decrease in isometric force, similar to that with propranolol. It is concluded that propranolol decreases the contractile force of the rat isolated diaphragm by a mechanism related to stabilization of excitable membranes.
Castile, R. G., O. F. Pedersen, et al. (1983). "Density dependence of maximal flow in dogs with central and peripheral obstruction." J Appl Physiol 55(3): 717-25.
In 12 anesthetized, tracheotomized, vagotomized, open-chested, mongrel dogs we measured end and side hole airway pressures during forced expiration using a Pitot static probe. Volume was obtained as the integral of flow from a dog plethysmograph with frequency response adequate to 20 Hz. Equal pressure points (EPPs) and choke points (CPs) were located with dogs breathing air or a mixture of 80% helium-20% oxygen (HeO2) before and after partial obstruction of the trachea and intravenous histamine and propranolol. At 50% of vital capacity (VC) the CP was in the trachea in 11 of 12 dogs. Partial obstruction of the trachea decreased flow during the plateau of the maximum expiratory flow-volume curve (MEFVC) with the CP remaining in the trachea. The MEFVC plateau was extended to a lower lung volume. At 50% of VC the EPP moved downstream and density dependence remained high. Histamine and propranolol caused EPPs and CPs to move towards the periphery and density dependence to decrease. The shape of the MEFVC changed as the plateau was shortened and, in some instances, abolished. A plateau on the MEFVC could be regenerated by partial obstruction of the trachea. This was accompanied by return of the CP to the trachea and an increase in density dependence. Changes in density dependence were found to be a result of both the relocation of sites of flow limitation and differences in local CP areas with HeO2 and air.
Austen, K. F., E. J. Corey, et al. (1983). "The effect of indomethacin on the contractile response of the guinea-pig lung parenchymal strip to leukotrienes B4, C4, D4 and E4." Br J Pharmacol 80(1): 47-53.
Indomethacin (1 microgram ml-1) almost totally inhibited the dose-dependent contractile response of isolated lung parenchymal strips of the guinea-pig (GPLS) to leukotriene B4 (LTB4) over the concentration range 0.18-18 nM. LTC4 (0.63 pM-63 nM)-induced contractions of GPLS were not significantly inhibited by indomethacin (1.0 and 10.0 micrograms ml-1) except when the highest LTC4 concentration (63 nM) was tested in the presence of indomethacin (10 micrograms ml-1). LTD4 (1.3 fM-13 nM)-induced contractions of GPLS were not significantly inhibited by indomethacin (0.1-10 micrograms ml-1) except for contractions induced by concentrations of LTD4 greater than 0.13 nM and 13 nM. Indomethacin 1 microgram ml-1 and 10 micrograms ml-1 inhibited the contractile response to 13 nM LTD4 by 37 and 16% respectively. LTE4 (2.3 fM-23 nM)-induced contractions of GPLS were not significantly inhibited by indomethacin (0.1-10 micrograms ml-1). Contraction due to LTE4 23 pM was significantly potentiated by indomethacin (1 microgram ml-1). Clotrimazole (10 microM) significantly inhibited LTD4-induced contractions of GPLS at concentrations greater than 13 pM but had no significant effect on LTC4-induced contractions. Cyclo-oxygenase products, probably principally thromboxane A2, are important secondary mediators of LTB4-induced contractions of GPLS but make little or no contribution to contractions of GPLS induced by LTC4, LTD4, and LTE4, except at higher concentrations of LTD4 and possibly LTC4. Certain concentrations of LTE4 may generate bronchodilator PGE2 in GPLS.
Weiss, J. W., J. M. Drazen, et al. (1982). "Comparative bronchoconstrictor effects of histamine, leukotriene C, and leukotriene D in normal human volunteers." Trans Assoc Am Physicians 95: 30-5.
Weiss, J. W., J. M. Drazen, et al. (1982). "Bronchoconstrictor effects of leukotriene C in humans." Science 216(4542): 196-8.
Maximum expiratory flow rate at 30 percent of vital capacity above residual volume served as an index of airway obstruction in comparing the effects of leukotriene C and histamine administered by aerosol to five normal persons. Leukotriene C was 600 to 9500 times more potent than histamine on a molar basis in producing an equivalent decrement in the residual volume. The leukotriene C response was slow in onset and prolonged, reminiscent of the effects of aerosol allergen challenge in asthmatic allergic subjects.
Rossing, T. H., A. S. Slutsky, et al. (1982). "CO2 elimination by high-frequency oscillations in dogs--effects of histamine infusion." J Appl Physiol 53(5): 1256-62.
Effective gas exchange can be achieved in normal dogs by ventilation at frequencies of 4-20 Hz using stroke volumes (SV) smaller than the anatomic dead space. CO2 elimination is largely a function of tracheal SV-frequency product (Vosc) in anesthetized, paralyzed dogs with normal lungs. To determine the effect of constriction of small airways on gas exchange during such high-frequency ventilation (HFV), we ventilated five anesthetized, paralyzed, and vagotomized dogs via a tracheal cannula before and during intravenous histamine infusion. Vosc was varied by varying the frequency while keeping SV constant. For low Vosc, CO2 elimination (VCO2) increased directly with Vosc during control and histamine experiments. At high Vosc, VCO2 continued to increase directly with Vosc during the control study, but during histamine infusion VCO2 was lower than control values. Eucapnia could be maintained in each dog during HFV, even during airway constriction. During histamine infusion the frequency-dependent mechanical properties of the lung influence the delivery of the HFV SV to the respiratory zone, and this may explain the lower VCO2 observed.
Pedersen, O. F., R. G. Castile, et al. (1982). "Density dependence of maximum expiratory flow in the dog." J Appl Physiol 53(2): 397-404.
Airway lateral and impaction pressures were measured during expiratory flow limitation in six anesthetized, vagotomized, tracheally intubated, open-chest dogs with the lungs filled with air or a mixture of 80% helium-20% oxygen (HeO2). Pressures were measured in the vicinity of equal pressure points (EPP) and choke points (CP). Maximum flow (Vmax) was ensured by demonstrating no increase in flow with a 50% increase of driving pressure. At 50% vital capacity, mean density dependence (VmaxHeO2/Vmaxair) was 1.58, which was less than 1.69 predicted for fully density-dependent flow. Transmural pressure and airway area at CP and EPP (located on air) were significantly less with HeO2 than with air. Frictional losses between the alveoli and CP were 40% greater with HeO2 than with air. These enhanced losses were mostly peripheral to the EPP. Frictional loss upstream from the EPP was 47% of the total pressure loss on air and increased to 70% on HeO2. The data at 50% VC suggest that these higher frictional losses with HeO2 resulted in decreased density dependence of Vmax due to different pressure distribution along the airway with a lower transmural pressure and smaller area at the CP.
Lewis, R. A., K. F. Austen, et al. (1982). "Structure, function, and metabolism of leukotriene constituents of SRS-A." Adv Prostaglandin Thromboxane Leukot Res 9: 137-51.
Lewis, R. A., J. M. Drazen, et al. (1982). "A review of recent contributions on biologically active products of arachidonate conversion." Int J Immunopharmacol 4(2): 85-90.
Leukotrienes (LTs) C4, D4 and E4, the recognized components of slow reacting substance of anaphylaxis (SRS-A), have previously been shown to have contractile activities for guinea pig pulmonary and ileal smooth muscles; LTB4 has been shown to possess chemotactic activity for neutrophils in vitro. Based on data obtained by the use of structural analogs of the SRS-A LTs and of LTB4, we have recently determined a number of the structural bases for the biological function of each moiety. With regard to the SRS-A leukotrienes, analogs differed from the native structures in the position of the peptide side chain and/or the hydroxyl group, the number and position of ethylenic bonds, the chirality at optically-active centers, or the structures of the four polar substituents in the C-1 to C-6 region. Analogs of LTB4, differing in the stereochemistry of their ethylenic bonds, were evaluated for chemotactic activity both in vitro, using human neutrophils, and in vivo intracutaneously in the rhesus monkey. We propose that true receptors exist on the pulmonary parenchyma of the guinea pig for the SRS-A LTs and on the primate neutrophil for LTB4. Further, LTC4, LTD4 and LTE4 have been shown to elicit a wheal and prolonged flare in human skin, whereas LTB4 evokes a time-dependent induration. The interaction of these secondary mediators may be critical to a fully developed host inflammatory response to both immunologic and non-immunologic injury.
Fanta, C. H., C. S. Venugopalan, et al. (1982). "Inhibition of bronchoconstriction in the guinea pig by a calcium channel blocker, nifedipine." Am Rev Respir Dis 125(1): 61-6.
We investigated the inhibitory effects of nifedipine, a calcium channel blocker, on airway smooth muscle constriction in the guinea pig. In vitro, nifedipine (0.003 to 3.0 microM) caused significant dose-dependent reversal of intrinsically existing tone in both tracheal spirals and parenchymal strips. Nifedipine also inhibited the constriction of tracheal spirals and parenchymal strips induced by two different agonists, histamine and carbachol. At a concentration of 3.0 microM, nifedipine increased by 48-fold the concentration of carbachol required to produce a 50% of maximal contraction of parenchymal strips, and by 5-fold the concentration of histamine. Increasing extracellular calcium ion concentration in the tissue baths significantly diminished the inhibitory action of nifedipine. In vivo, nifedipine (30 micrograms/kg body weight given intravenously) did not alter pulmonary resistance or dynamic compliance. It did, however, attenuate histamine-induced bronchoconstriction in 3 of 5 animals studied. In response to the maximal dose of histamine infused, mean pulmonary resistance rose 40 +/- 16% (SEM) after nifedipine versus 182 +/- 65% in the control animals (p less than 0.025) and mean dynamic compliance decreased 35 +/- 8% after nifedipine versus 58 +/- 6% in the control animals (p less than 0.01). Thus, this calcium channel blocker inhibits mediator-induced constriction of both central and peripheral airway contractile tissues, a finding of potential clinical applicability.
Drazen, J. M., C. S. Venugopalan, et al. (1982). "Effects of leukotriene E on pulmonary mechanics in the guinea pig." Am Rev Respir Dis 125(3): 290-4.
The effects of intravenously infused 5(S)hydroxy-6(R)-S-cysteinyl-7,9,-trans,11,14,-cis eicosatetraenoic acid (leukotriene E) (LTE), one of the leukotriene constituents of slow-reacting substance of anaphylaxis (SRS-A), on pulmonary resistance (RL) and dynamic compliance (Cdyn), breathing frequency, and mean systemic arterial pressure were determined in both anesthetized and unanesthetized guinea pigs. The LTE caused a dose-dependent increase of RL and decrease in Cdyn over the range of doses from 100 to 10,000 ng/kg with significance effects at the highest doses. The onset of effect after a significant dose occurred within 30 s and was maximal 1 to 3 min after infusion. The LTE elicits a significantly greater effect on RL for a given change in Cdyn than occurs with LTC or LTD indicating that LTE is a less selective peripheral airway agonist than LTC or LTD. The LTD infusion resembled LTC or LTD in evoking a systemic arterial hypotension that was preceded by a brief initial period of hypertension in unanesthetized animals.
Drazen, J. M., C. F. O'Cain, et al. (1982). "Experimental induction of chronic bronchitis in dogs: effects on airway obstruction and responsiveness." Am Rev Respir Dis 126(1): 75-9.
Chronic bronchitis was induced in 6 mongrel dogs by chronic exposure to SO2 gas; the degree of chronic airway obstruction and the effects on airway responsiveness to inhaled histamine, carbachol, and prostaglandin F2 alpha were examined. Five dogs developed chronic airway obstruction, as indicated by an increase in pulmonary resistance, and clinical mucous hypersecretion. In addition, in each of the animals in which chronic airway obstruction developed there was a decrease in the airway responsiveness to inhaled mediators. Those findings demonstrate that induction of chronic bronchitis in dogs results in hyporesponsiveness to inhaled mediators, a finding distinctly different from that reported in human subjects with naturally occurring disease.
Yanta, M. A., S. H. Loring, et al. (1981). "Direct and reflex bronchoconstriction induced by histamine aerosol inhalation in dogs." J Appl Physiol 50(4): 869-73.
Histamine aerosols were administered to nine anesthetized, paralyzed, mechanically ventilated mongrel dogs with the cervical vagi first intact, then sectioned, and then peripherally stimulated at two intensities. Pulmonary resistance (RL) was measured, and dose-response curves were constructed in the four conditions. All dogs had dose-related increases in RL with increasing histamine aerosol concentrations. After the vagi were cut, the degree to which constant levels of vagal stimulation altered the dose-response relationships was assessed by examining the slopes and positions of the RL vs. histamine curves. Four of the nine animals studied showed evidence of increasing vagal efferent activity as the concentration of histamine in the aerosol increased, but three did not. Two of the dogs had equivocal responses in that increasing activity was suggested but not clearly demonstrated. These results indicate that, in addition to direct effects of histamine, the extent of and basis for vagal interaction with this stimulus varies among dogs. The results suggest that the basis of vagal interaction is related to either constant efferent activity (tone) or increasing efferent activity (reflexes).
Yanta, M. A., J. R. Snapper, et al. (1981). "Airway responsiveness to inhaled mediators: relationship to epithelial thickness and secretory cell number." Am Rev Respir Dis 124(3): 337-40.
Naturally occurring variations in airway responsiveness to inhaled mediators were correlated with various anatomic indexes thought to be related to airway responsiveness. Specifically, the airways of 2 relatively unresponsive and 3 relatively responsive dogs were compared in terms of epithelial thickness, secretory cell number, smooth muscle thickness, and airway mucous gland number and size. More responsive dogs were found to have thinner epithelium and higher secretory cell counts than less responsive dogs. No significant differences between the 2 groups were noted with respect to smooth muscle thickness or mucous gland number and size. Although these observations identify an association between these anatomic features and airway responsiveness, it does not imply a causal relationship.
Snapper, J. R., P. S. Braasch, et al. (1981). "Effects of beta adrenergic blockade on histamine and prostaglandin-F2 alpha responsiveness in the dog." J Allergy Clin Immunol 67(3): 199-205.
To examine whether either the degree of existing beta adrenergic tone or the magnitude of beta adrenergic response during bronchoconstriction might account for the differences that exist between dogs in their pulmonary responsiveness to aerosol challenge with bronchoconstrictor agents, dose-response curves were performed in a group of dogs to either histamine or prostaglandin-F2 alpha, both before beta blockade with propranolol. Beta blocked had no significant effect on control values of dynamic compliance (Cdyn) or resistance of the lung (RL) or on pulmonary responsiveness to prostaglandin f2 alpha. Although propranolol did not have a significant effect on aerosol responsiveness to histamine for the group of dogs taken together, those dogs initially least responsive to aerosol histamine did become more responsive after beta blockade. This effect of beta blockade was statistically significant only for Cdyn and not for RL, suggesting enhancement of peripheral airway effects. We conclude that a beta adrenergic mechanism may contribute to the range of responsiveness found among dogs in their pulmonary responsiveness to histamine but that other as yet undefined factors must also contribute to the differences that exist among dogs in their pulmonary responsiveness to bronchoconstrictor agents.
Slutsky, A. S., G. G. Berdine, et al. (1981). "Oscillatory flow and quasi-steady behavior in a model of human central airways." J Appl Physiol 50(6): 1293-9.
We studied biased oscillatory flow in a model of human central airways to examine under what conditions oscillatory flow deviated from steady flow. Although the steady flow resistance of the model was 25% less than the oscillatory flow resistance of the model at 15Hz, the overall inertance of the model did not change over the range of frequencies from 5 to 15 Hz, suggesting that frequency-dependent inertial distortion of velocity profiles did not alter central airway pressure-flow relationships over this frequency range. In a given terminal branch of the model, instantaneous oscillatory flow at 2 and 5 Hz could be predicted well from the steady flow distribution, but with increasing frequency the oscillatory flow from the branch deviated more from the steady flow predictions. A significant component of this deviation was due to a phase shift between predicted and measured oscillatory flow. We conclude that the major frequency-dependent behavior flow in the human central airways is a phasic redistribution of flow above 7 Hz, resulting from the asymmetric distribution of inertances in this structure.
Slutsky, A. S., R. Brown, et al. (1981). "High-frequency ventilation: a promising new approach to mechanical ventilation." Med Instrum 15(4): 229-33.
Adequate pulmonary ventilation can be achieved in experimental animals and in humans using tidal volumes on the order of the anatomic dead space volume applied at very high ventilatory frequencies (3-30 Hz). Classical mechanism of gas exchange cannot account for these paradoxical observations, but theories based on the concept of augmented diffusion may provide an adequate explanation for this phenomenon. Even though the exact mechanisms accounting for gas exchange are not well understood, a number of successful ventilators have been designed and tested based on the concept of small volume/high frequency ventilation. The differences among these various ventilators are compared and contrasted and possible clinical uses of the technique are discussed.
Slutsky, A. S., J. M. Drazen, et al. (1981). "Alveolar pressure-airflow characteristics in humans breathing air, He-O2, and SF6-O2." J Appl Physiol 51(4): 1033-7.
In a system of rigid tubes under steady flow conditions, the coefficient of friction [CF = 2 delta P/(rho V2/A2)] (where delta P is pressure drop, rho is density, V is flow, and A is cross-sectional area) should be a unique function of Reynolds' number (Re). Recently it has been shown that at any given Re, the value of CF using transpulmonary pressure (PL) was lower when breathing He-O2 compared with air (Lisboa et al., J. Appl. Physiol.: Respirat. Environ. Exercise Physiol. 48: 878-885, 1980). One explanation for this discontinuity is that PL includes the pressure drop due to tissue viscance, which is independent of V, and thus would lead to an overestimate of CF on air compared with He-O2 at any Re. We tested this hypothesis by measuring V related to alveolar pressure, rather than PL, in normal subjects breathing air, He-O2, and SF6-O2. In each subject, for a given Re, CF was greatest breathing SF6-O2 and lowest breathing He-O2, similar to results using PL. Thus tissue viscance is not the sole cause of the discontinuous plot of CF vs. Re, and this phenomenon must be due to other factors, such as changing geometry or nonsteady behavior.
Slutsky, A. S., R. D. Kamm, et al. (1981). "Effects of frequency, tidal volume, and lung volume on CO2 elimination in dogs by high frequency (2-30 Hz), low tidal volume ventilation." J Clin Invest 68(6): 1475-84.
Recent studies have shown that effective pulmonary ventilation is possible with tidal volumes (VT) less than the anatomic dead-space if the oscillatory frequency (f) is sufficiently large. We systematically studied the effect on pulmonary CO2 elimination (VCO2) of varying f (2-30 Hz) and VT (1-7 ml/kg) as well as lung volume (VL) in 13 anesthetized, paralyzed dogs in order to examine the contribution of those variables that are thought to be important in determining gas exchange by high frequency ventilation. All experiments were performed when the alveolar PCO2 was 40 +/- 1.5 mm Hg. In all studies, VCO2 increased monotonically with f at constant VT. We quantitated the effects of f and VT on VCO2 by using the dimensionless equation VCO2/VOSC = a(VT/VTo)b(f/fo)c where: VOSC = f X VT, VTo = mean VT, fo = mean f and a, b, c, are constants obtained by multiple regression. The mean values of a, b, and c for all dogs were 2.12 X 10(-3), 0.49, and 0.08, respectively. The most important variable in determining VCO2 was VOSC; however, there was considerable variability among dogs in the independent effect of VT and f on VCO2, with a doubling of VT at a constant VOSC causing changes in VCO2 ranging from -13 to +110% (mean = +35%). Increasing VL from functional residual capacity (FRC) to the lung volume at an airway opening minus body surface pressure of 25 cm H2O had no significant effect on VCO2.
Rossing, T. H., A. S. Slutsky, et al. (1981). "Tidal volume and frequency dependence of carbon dioxide elimination by high-frequency ventilation." N Engl J Med 305(23): 1375-9.
Six patients with chronic respiratory failure received mechanical ventilation with tidal volumes less than or equal to the dead-space volume, at frequencies of 30 to 900 breaths per minute. The rate of elimination of carbon dioxide from the ventilator system during a brief trial of high-frequency ventilation accurately predicted the long-term effectiveness of a given combination of frequency and tidal volume. Below frequencies of about 200 breaths per minute, the volume of carbon dioxide eliminated from these patients was most strongly related to the product of frequency and tidal volume; at higher frequencies, carbon dioxide elimination was determined by the tidal volume and was independent of frequency. These results suggest that although the effectiveness of high-frequency ventilation is primarily a function of the product of tidal volume and frequency, above a critical frequency the mechanical characteristics of the lung reduce gas transport by limiting the volume transmitted to the periphery of the lung.
Loring, S. H., J. M. Drazen, et al. (1981). "Vagal stimulation and aerosol histamine increase hysteresis of lung recoil." J Appl Physiol 51(2): 477-84.
Bronchoconstriction changes pulmonary resistance and dynamic compliance by altering both airway properties and dynamic lung tissue recoil. To assess the contribution of recoil, we measured transpulmonary pressure in anesthetized open-chest dogs during sinusoidal ventilation with gas flow and during sinusoidal compression of intrapulmonary gas without flow. Measurements with gas flow characterized total pulmonary behavior, including the contribution of gas flow in airways, whereas measurements during gas compression characterized lung tissue recoil alone. Histamine aerosol produced a 54% decrease in dynamic compliance, a 465% increase in total pulmonary resistance, and a 153% increase in pressure-volume hysteresis of dynamic recoil. Vagal stimulation produced a 31% decrease in dynamic compliance, a 135% increase in total pulmonary resistance, an 82% increase in the hysteresis of recoil, and a 15% increase in mean recoil pressure. At slow oscillation frequencies (0.2 Hz) and high transpulmonary pressures (10 cmH2O), hysteresis of lung recoil contributes substantially to total pulmonary resistance, and changes in dynamic lung recoil can account for much (35%) of the increase in pulmonary resistance seen with bronchoconstriction.
Loring, S. H., R. H. Ingram, Jr., et al. (1981). "Effects of lung inflation on airway and tissue responses to aerosol histamine." J Appl Physiol 51(4): 806-11.
The pulmonary effects of aerosol histamine exposure include an increase in pulmonary resistance (RL) and a decrease in dynamic compliance (Cdyn). These changes are substantially reversed by inflation of the lungs to 30 cmH2O transpulmonary pressure (TLC). Although histamine has been shown to change both the airway and tissue components of RL and Cdyn, it is not known whether lung inflation reverses the changes in airways, in tissue, or in both. We studied six anesthetized, paralyzed, open-chest dogs. We sequentially measured RL and Cdyn during oscillations in lung volume at 0.6 Hz with the airway open and during compression-decompression of the lungs without tracheal airflow. In the control state after saline aerosol, inflation to TLC resulted in a slight increase in compliance and a decrease in the tissue component of RL. Aerosol histamine exposure caused an increase in resistance and a decrease in compliance due to both airway and tissue changes. Inflation of the lungs to TLC largely reversed the changes due to airway constriction without consistently affecting the changes due to tissue. We conclude that after histamine exposure smooth muscle responsible for airway narrowing is stretched by lung inflation but that contractile elements responsible for alterations in air-space distensibility and hysteresis of dynamic lung recoil are either not stretched by lung inflation or are stretched and shorten again rapidly.
Lewis, R. A., J. M. Drazen, et al. (1981). "Contractile activities of structural analogs of leukotrienes C and D: role of the polar substituents." Proc Natl Acad Sci U S A 78(7): 4579-83.
Twenty-three structural analogs of the leukotriene components of slow reacting substance of anaphylaxis (SRS-A), in which the polar regions of the leukotriene were systematically modified, were tested for their contractile activities on guinea pig pulmonary parenchymal strips and guinea pig ileum. The structural modifications allowed evaluation of the separate contributions of the four polar units in the C-1 to C-6 region of the SRS-A leukotrienes to smooth muscle spasmogenic activity. The free NH2-terminal amino group of the S-linked peptide was necessary for full activity, and its deletion or substitution reduced activity by more than one but less than two orders of magnitude. A similar level of importance was apparent for the free glycine carboxyl group. In contrast, a free eicosanoid carboxyl at C-1 is not required for full activity on the airway and for substantial activity on the ileum. A role for the C-5 hydroxyl is indicated by the inactivity of the one available 5-desoxy analog. Nucleophilic, divalent sulfur is not critical to leukotriene D (LTD) activity, in that one sulfoxide had substantial function. The conformational relationship between the eicosanoid and peptide moieties of LTD is of considerable importance in that epimers at the C-5 or C-6 position were less active than LTD by more than two orders of magnitude. Several lines of evidence suggest that the relative geometrical arrangement of the C20 chain and the peptide unit is important to activity, consistent with the existence of a true receptor for LTD.
Lewis, R. A., E. J. Goetzl, et al. (1981). "Functional characterization of synthetic leukotriene B and its stereochemical isomers." J Exp Med 154(4): 1243-8.
Leukotriene B (LTB), a potent lipid chemotactic factor for neutrophils, is 5S,12R-dihydroxy-6,14-cis,8,10-trans-eicosatetraenoic acid (Fig 1), based upon direct comparison of natural LTB with synthetic 5S,12R-dihydroxy-6,8,10,14-eicosatetraenoic acid (5,12-di-HETE) stereoisomers in three biological assays. Of the six synthetic stereoisomers evaluated, only the 5S,12R,6,14-cis,8,10-trans compound had chemotactic potency for human neutrophils in vitro that was comparable to that of natural LTB, with a concentration of 3 X 10(9-9) M eliciting a one-half maximum response. In contrast, the racemic mixture of 5R,12R- and 5S,12S-6,10-trans,8,14-cis, the racemic mixture of 5S,12R- and 5R,12S-6,10-trans,8,14-cis, the 5S,12R-6,8-trans,10,14-cis, the 5S,12R-6,8,10-trans,14-cis, and the 5S,12S-6,8,10-trans,14-cis stereoisomers required concentrations of 3 X 10(-7) to 1 X 10(-6) M to elicit comparable responses. Only natural LTB and its synthetic counterpart elicited a local neutrophil infiltration when injected into the skin of the rhesus monkey at 10 ng and 100 ng per site. Natural and synthetic LTB at a concentration of 3 X 10(-8) M each provoked an EC25 contractile response of guinea pig pulmonary parenchymal strips in vitro, whereas the other four tested stereoisomers of 5,12-di-HETE were inactive at this concentration. Structure-function analyses suggest that the neutrophil chemotactic activity depends critically upon the C-1 to C-12 domain, including the stereochemistry of the 6-,8-,and 10-olefinic bonds and the presence of both hydroxyl groups.
Jackson, A. C., S. H. Loring, et al. (1981). "Serial distribution of bronchoconstriction induced by vagal stimulation or histamine." J Appl Physiol 50(6): 1286-92.
We compared the relative site of airway responses with histamine aerosol and electrical stimulation of the vagi in dogs that were anesthetized, vagotomized, mechanically ventilated, and treated with propranolol. We made measurements of pulmonary resistance by forced oscillations and of dead-space volume as indirect indicators of airway size. Direct measures of airway size were obtained from radiographic bronchograms and from acoustically equivalent airway areas as a function of distance, computed from pulse response data. During vagal stimulation there were marked increases in pulmonary resistance, decreases in dead space, and reduction in acoustic cross-sectional area at all distances. In contrast, after inhalation of enough aerosol histamine to increase pulmonary resistance approximately as much as it did during vagal stimulation, we observed little ro no reduction in dead space and reductions in acoustic cross-sectional area that were most marked in distal airways. The findings were confirmed by the radiographic bronchograms and are consistent with observations reported by others. These observations confirm previous data and demonstrate the utility of this technique for in vivo measurements.
Drazen, J. M., R. A. Lewis, et al. (1981). "Contractile activities of structural analogs of leukotrienes C and D: necessity of a hydrophobic region." Proc Natl Acad Sci U S A 78(5): 3195-8.
Sixteen structural analogs of leukotrienes C and D were tested for their contractile activities on guinea pig pulmonary parenchymal strip and ileum. The analogs differed from the native structures in the position of either the thioether-linked peptide side chain or the hydroxyl group (or both) or in the number and positions of ethylenic bonds. Analogs in which the thioether-linked peptide chain was attached other than at the C-6 position had substantial reductions in activity on both smooth muscle preparations, whereas analogs in which the various ethylenic bonds were saturated retained substantial contractile activity in both assays. These observations demonstrate that, although a hydrophobic region of the eicosinoid is necessary for contractile activity, the length of this segment is more critical than its precise stereochemistry. Analogs of leukotrienes based on the possibility of parallel biosynthetic routes deriving from 8-, 11-, and 15-hydroperoxyeicosatetraenoic acid as precursors were found to effect a comparatively weak contractile response so that their role as biological agents in this respect seems unlikely.
Bach, M. K., J. R. Brashler, et al. (1981). "Slow-reacting substances from rat leukocytes: selective action on the airways, and progress toward elucidation of their structure." Kroc Found Ser 14: 37-50.
Snapper, J. R., P. S. Braasch, et al. (1980). "In vivo effect of cimetidine on canine pulmonary responsiveness to aerosol histamine." J Allergy Clin Immunol 66(1): 70-4.
A series of experiments were designed to discover whether pulmonary histamine H2 receptors might be of physiologic importance in vivo in the dog. Dose-response curves were performed to aerosol histamine in 11 dogs both before and 1 hr after H2 receptor blockade with cimetidine (1 mg/kg as a rapid intravenous infusion). Cimetidine had no significant effect on control values of dynamic compliance or resistance of the lung. In the 11 dogs tested H2 receptor antagonism significantly potentiated (p less than 0.05) the animals' pulmonary responsiveness to aerosol histamine. The potentiation of histamine constrictor e-fects produced by cimetidine were more marked on those dogs initially least responsive to aerosol histamine (p less than 0.01). We have found evidence for the presence of inhibitory H2 receptors in canine airways and for the distribution of these receptors among dogs, explaining in part the previously described differences among dogs in the pulmonary responsiveness to aerosol histamine.
Snapper, J. R., P. S. Braasch, et al. (1980). "Comparison of the responsiveness to histamine and to Ascaris suum challenge in dogs." Am Rev Respir Dis 122(5): 775-80.
The pulmonary and dermal sensitivity of a group of mongrel dogs to an extract of Ascaris suum protein was compared with the pulmonary and dermal sensitivity to histamine in this same group. We found a modest but significant correlation in the entire population between skin test reaction to histamine and to A. suum protein (r = 0.52, p < 0.05), but when the skin test results were compared with those of aerosol challenge, no significant correlation was found. However, when those dogs with reactions to histamine challenge that fell within a narrow range were considered as a separate group, there was a significant correlation between the reactions of aerosol challenge with A. suum and those of the skin tests with A. suum (r = 0.56, p < 0.025). These findings were consistent with the hypothesis that aerosol bronchoconstrictor responsiveness and immunologic responsiveness are separate attributes that combine to determine airway responsiveness to a specific antigen.
Slutsky, A. S., G. G. Berdine, et al. (1980). "Steady flow in a model of human central airways." J Appl Physiol 49(3): 417-23.
We studied the pressure-flow relationships and flow distribution under steady conditions in a model of human central airways, over a range of tracheal Reynolds' numbers (350-30,000) by using air or helium. We found that the Moody diagram [log coefficient of friction CF = delta P/[1/2 rho (V2/A2)] vs. log Reynolds' number (Re)] had a slope of -1 for Re less than 500, a slope 0 for Re greater than 10,000, and slopes between -1 and 0 for 500 less than or equal to Re less than or equal to 10,000. The distribution of flow among branches was dependent on tracheal Reynolds' number so that, as tracheal Reynolds' number increased, the upper lobes received proportionally less of the total flow than the lower lobes. Because the airways in the upper lobes generally had greater branching angles than those in the lower lobes, this result was consistent with the hypothesis that the effective resistances introduced by branching angles was flow dependent, increasing proportionally more the greater the angle.
Schneider, M. W. and J. M. Drazen (1980). "Comparative in vitro effects of arachidonic acid metabolites on tracheal spirals and parenchymal strips." Am Rev Respir Dis 121(5): 835-42.
We compared the pharmacologic effects of a number of oxidative products of arachidonic acid metabolism, including prostaglandin (PG) F2 alpha, PGD2, PGI2, PGE2 6-keto-PGF1 alpha, and the 9 alpha, 11 alpha and 11 alpha, 9 alpha cyclic ether endoperoxide analogues, with that of histamine on guinea pig tracheal spirals and lung parenchymal strips. These agents demonstrated different profiles of activity on the tracheal (central) and parenchymal (peripheral) airway tissues. None of the metabolites studied exceeded the ability of histamine to constrict the tracheal spirals, whereas the cyclic ether endoperoxide analogues and PGD2 were as good as, or better, constrictors of the parenchymal strips than histamine. This suggests that these mediators, which are formed during hypersensitivity reactions, may play an important role in the peripheral airway constriction that is a part of this syndrome.
Lewis, R. A., K. F. Austen, et al. (1980). "Slow reacting substances of anaphylaxis: identification of leukotrienes C-1 and D from human and rat sources." Proc Natl Acad Sci U S A 77(6): 3710-4.
Lewis, R. A., J. M. Drazen, et al. (1980). "Identification of the C(6)-S-conjugate of leukotriene A with cysteine as a naturally occurring slow reacting substance of anaphylaxis (SRS-A). Importance of the 11-cis-geometry for biological activity." Biochem Biophys Res Commun 96(1): 271-7.
Drazen, J. M., C. S. Venugopalan, et al. (1980). "Alteration of histamine response by H2-receptor antagonism in the guinea pig." J Appl Physiol 48(4): 613-8.
Effects of H2-receptor antagonism on the response to histamine was studied in the guinea pig in vivo and in vitro. The H2-receptor antagonist, metiamide (100 micro M), resulted in an enhanced histamine response in eight of eight parenchymal strips and in four of eight tracheal spirals. On the average the parenchymal strips were 20-fold more sensitive to histamine (P less than 0.001), whereas the tracheal spirals demonstrated an insignificant, 20%, increase in sensitivity after metiamide treatment. These results are consistent with the hypothesis that there are inhibitory H2-receptors in guinea pig airways and they predominate in the periphery. When we determined the effects of H2-antagonism on the histamine response in vivo we found that the histamine response was enhanced only in animals that had been treated with the beta-receptor antagonist propranolol. In these animals there was a mean 2.2-fold increase in histamine sensitivity. These results suggest that although there are inhibitory H2-receptors in the guinea pig lung, their role in modulating the in vivo response is much less than beta-adrenergic mechanisms.
Drazen, J. M., K. F. Austen, et al. (1980). "Comparative airway and vascular activities of leukotrienes C-1 and D in vivo and in vitro." Proc Natl Acad Sci U S A 77(7): 4354-8.
The pharmacologic activities of leukotrienes C-1 and D(LTC-1 and LTD), constituents of slow reacting substance of anaphylaxis (SRS-A), were evaluated in vitro on airway contractile tissues and in vivo on pulmonary mechanical function, mean systemic arterial pressure, and cutaneous microcirculation. In vitro both LTC-1 and LTD were potent and selective peripheral airway agonists, being more active than histamine; furthermore, LTD was active on peripheral airways at concentrations 1/100th those of LTC-1. The concentration-effect relationship for LTD and the profile of antagonism by FPL 55712 are consistent with the activity of this molecule at two separate peripheral airway receptors. In vivo, LTC-1 and LTD were nearly equally active in their effects on pulmonary mechanics, and the pattern of alterations was consistent with the predominant site of action being in the lung periphery. Furthermore, both agents had a direct systemic arterial hypotensive effect and were vasoactive on the cutaneous microcirculation. Thus, these compounds are likely to be major mediators of the pathologic alterations in immediate type hypersensitivity reactions in which peripheral airway constriction and hypotension are prominent features.
Chesrown, S. E., C. S. Venugopalan, et al. (1980). "In vivo demonstration of nonadrenergic inhibitory innervation of the guinea pig trachea." J Clin Invest 65(2): 314-20.
Bach, M. K., J. R. Brashler, et al. (1980). "Two rat mononuclear cell-derived slow reacting substances: kinetic evidence that the peripheral airways-selective spasmogen is derived from a nonselectively acting precursor." Immunopharmacology 2(4): 361-73.
The purpose of this study was to extend our knowledge of two slow reacting substances that are formed in rat mononuclear cells upon stimulation by the ionophore A 23187. Slow reacting substance (SRS) preparations were further purified through the sequential high performance liquid chromatographic procedures starting with exudates from cells that had been prelabeled with tritiated arachidonate. Approximately 2% of the released radioactivity (0.3% of the radioactivity that was taken up by the cells) cochromatographed with biologic activity in both preparations. Kinetic studies revealed that one of the SRSs was formed more rapidly than the other and analysis by nonlinear computer modeling techniques suggests a possible product-precursor relationship between the two substances. Activity of the preparations on guinea pig lung parenchyma and trachea was compared using a histamine standard; only the more slowly formed substance had the selective activity on the parenchyma that we associate with slow reacting substance of anaphylaxis (SRS-A). Taken together, these findings suggest that a material which may be a precursor of SRS-A, if it is also formed and accumulated in vivo, may contribute to the more central airway constriction which is seen in some asthmatics.
Snapper, J. R., J. M. Drazen, et al. (1979). "Vagal effects on histamine, carbachol, and prostaglandin F2 alpha responsiveness in the dog." J Appl Physiol 47(1): 13-6.
To investigate whether an individual dog's responsiveness to histamine correlates with its responsiveness to other bronchoconstrictor agents and to investigate whether varying vagal effects account for the previously described range of histamine responsiveness, we compared dose-effect relationships of histamine to those of two pharmacological dissimilar agents, carbachol and prostaglandin F2 alpha before and after vagal blockade. There was a highly significant correlation between histamine and both carbachol (P less than 0.001) and prostaglandin F2 alpha (P less than 0.001) responsiveness. The range of responsiveness to prostaglandin F2 alpha was greater than that for histamine or carbachol. When histamine and carbachol were given simultaneously, a purely additive effect was found. Vagal blockade had no significant effect on histamine or carbachol responsiveness, but significantly diminished the responsiveness to prostaglandin F2 alpha; however, it neither narrowed the range nor changed the rank order of responsiveness. We conclude that the range of responsiveness is not specific for any one agent and that vagal mechanisms do not play a role in producing this range.
Slutsky, A. S. and J. M. Drazen (1979). "Estimating central and peripheral respiratory resistance: an alternative analysis." J Appl Physiol 47(6): 1325-31.
Pimmel et al (J. Appl. Physiol.: Respirat. Environ. Exercise Physiol. 45: 375--380, 1978) recently presented an analysis of the frequency dependence of respiratory resistance (Rrs) based on a simple electrical analog of the respiratory system that allows estimation of the central (Rc) and peripheral (Rp) components of Rrs. The method by which they determine these parameters from the experimental data is based on a number of unproven assumptions. Using the same electrical analog, we present an analysis that allows calculation of these parameters, as well as the corner frequency of the network (f1), without need for similar assumptions. Our technique is based on fitting the resistances (RTh) measured over a range of frequencies (f) to the exact solution of the network given by RTh = Rc + Rpf1(2)/f2 + f1(2)). Using the transformation X = 1/(f2 + f1(2), the equation becomes a linear relationship between RTh and X allowing the resistances to be determined by linear regression. Reanalysis of Pimmel et al.'s data demonstrated that the assumptions of a constant f1, and the equivalence of RTh at 0 Hz to RTh at 1 Hz in invalid under certain conditions. Thus, if one is to use the electrical analog to partition Rrs into its central and peripheral components, one should use the analytic approach suggested here that does not rely on these assumptions.
Loring, S. H., E. A. Elliott, et al. (1979). "Kinetic energy loss and convective acceleration in respiratory resistance measurements." Lung 156(1): 33-42.
Drazen, J. M., R. A. Lewis, et al. (1979). "Differential effects of a partially purified preparation of slow-reacting substance of anaphylaxis on guinea pig tracheal spirals and parenchymal strips." J Clin Invest 63(1): 1-5.
The contractile effects of partially purified slow-reacting substance of anaphylaxis (SRS-A) and histamine were compared on isolated guinea pig tracheal spirals and parenchymal strips. Histamine was equally active on both isolated tissues in a concentration-related fashion. SRS-A (0.1--10.0 U/ml) produced a concentration-related effect on parenchymal strips, whereas the tracheal spiral was 100 times less sensitive to this mediator. The contractile activity of SRS-A on parenchymal strips was diminished by incubation with limpet arylsulfatase and antagonized by FPL 55712, a known SRS-A antagonist. SRS-A, further purified by high pressure liquid chromatography, also demonstrated this preferential activity on guinea pig parenchymal strips. These data are consistent with the hypothesis, based on previous in vivo observations, that SRS-A is a selective peripheral airway constrictor.
Drazen, J. M., M. W. Schneider, et al. (1979). "Bronchodilator activity of dimaprit in the guinea pig in vitro and in vivo." Eur J Pharmacol 55(3): 233-9.
The bronchodilator activity of the H2-recptor agonist, dimaprit, was assessed in vitro and in vivo. In vitro dimaprit relaxed guinea pig tracheal spirals and parenchymal strips that were constricted by the H1 receptor agonist, 2-PEA, or by carbachol. The H2-receptor antagonist, metiamide, inhibited this effect of dimaprit in vitro on both tissues constricted by 2-PEA but not on the carbachol constricted tracheal spiral. Intravenous infusion of dimaprit in the intact guinea pig resulted in reversal of bronchoconstriction induced by subcutaneous injection of 2-PEA. In vivo pretreatment with the H2-recptor antagonist, metiamide, resulted in a diminished sensitivity to the bronchodilating effects of intravenous dimaprit.
Drazen, J. M., S. H. Loring, et al. (1979). "Effects of volume history on airway changes induced by histamine or vagal stimulation." J Appl Physiol 47(4): 657-65.
Snapper, J. R., J. M. Drazen, et al. (1978). "Distribution of pulmonary responsiveness to aerosol histamine in dogs." J Appl Physiol 44(5): 738-42.
Dose-response curves to aerosol histamine in 102 anesthetized, intubated, spontaneously breathing dogs revealed a spectrum of airway responsiveness with a greater than 40-fold difference between the most and the least sensitive animals. The frequency distribution of responses fits a log normal distribution. No correlation was found between sex, age, or control values of dynamic compliance (Cdyn) and lung resistance (RL) and the dose of histamine required to cause a response. Repetitive studies in 17 dogs observed for up to 20 mo showed that the dose at which an individual dog would respond was reproducible within a narrow range and that the differences between dogs were highly significant (P greater than 0.001). The long-term reproducibility of the response to aerosol histamine in individual dogs suggests that short-term reversible airway insults are not responsible for the range in responses noted between animals.
Loring, S. H., J. M. Drazen, et al. (1978). "Vagal and aerosol histamine interactions on airway responses in dogs." J Appl Physiol 45(1): 40-4.
Histamine aerosol was administered to 10 anesthetized paralyzed artificially ventilated dogs whose vagi were first intact, then cut, and then peripherally stimulated. Pulmonary resistance (RL) was measured and dose-response curves determined in the three conditions. The dogs were divided into two groups based on the initial response to histamine with the vagi intact. The low-dose (LD) group had a greater than or equal to 50% increase in RL when exposed to a histamine concentration of 1.0 mg/ml. The high-dose (HD) group had a greater than or equal to 50% increase in RL when exposed to an aerosol containing 3.0 mg/ml histamine or more. In both groups there was a dose-related increase in RL with histamine with the vagi intact, cut, or stimulated. In three of the LD dogs there was a greater than additive interaction between vagal stimulation and inhaled histamine, whereas in the HD dogs the interaction was at most additive. With the vagi cut, both groups had a significantly lesser histamine response. The results show that differences in histamine responsiveness between dogs is in part related to varying degrees of nonreflex histamine-vagal interaction.
Ingram, R. H., Jr. and J. M. Drazen (1978). "Effects of preferential deposition of histamine in the human airway." Am Rev Respir Dis 118(2): 445-6.
Drazen, J. M., C. S. Venugopalan, et al. (1978). "H2 receptor mediated inhibition of immediate type hypersensitivity reactions in vivo." Am Rev Respir Dis 117(3): 479-84.
The effects of H2-blocking agents and the H2 receptor agonist, 4-methylhistamine, on the severity of anaphylactic reactions were studied in the guinea pig in vivo. The increase in gas volume of the lungs 90 sec after intravenous infusion of ovalbumin in animals immunized previously by intraperitoneal ovalbumin injection was used as an index of the severity of the reaction in vivo. The H2 receptor antagonists burimamide (1.0 and 3.0 mg per kg) and metiamide (3 mg per kg) significantly increased the severity of the reaction but did not significantly alter the effects of subcutaneous histamine. Neither 3 nor 30 mg of cimetidine per kg increased the severity of the reaction, and the higher dose significantly blunted the response to subcutaneous histamine. The H2 receptor agonist, 4-methylhistamine, significantly diminished the severity of the reation. These experiments demonstrate that H2 receptor stimulation may act to limit the severity of the anaphylactic reactions in vivo.
Drazen, J. M. (1978). "Adrenergic influences on histamine-mediated bronchoconstriction in the guinea pig." J Appl Physiol 44(3): 340-5.
Intravenous infusion of histamine results in a fall in dynamic pulmonary compliance (Cdyn) in the unanesthetized guinea pig. During a prolonged infusion of histamine (30-200 s) a minimum value of Cdyn is reached and sustained after 30 s. Propranolol (10 mg/kg) enhanced this steady-state response in both normal and adrenally ablated guinea pigs to the same degree. After the infusion was terminated, normal guinea pigs recovered briskly, whereas guinea pigs whose adrenals had been ablated recovered slowly. Propranolol prolonged the recovery from the histamine-mediated fall in Cdyn in normal guinea pigs, but had no significant effect on the pattern of recovery in adrenally ablated animals. These experiments suggest that during a histamine infusion nonadrenal adrenergic factors modify the histamine response, but the brisk recovery from histamine is under the influence of adrenal factors.
Drazen, J. M. and M. W. Schneider (1978). "Comparative responses of tracheal spirals and parenchymal strips to histamine and carbachol in vitro." J Clin Invest 61(6): 1441-7.
The responses of isolated guinea pig tracheal spirals and parenchymal strips to histamine and carbachol were compared. The parenchymal strip, a 1.5 x 1.5 x 20-mm strip cut from the periphery of the lung, constricted at a lower dose and had a larger maximal response to histamine than to carbachol. In contrast, the response of the tracheal spiral to equimolar doses of histamine or carbachol was the same. The responsiveness of both muscle strips to histamine was decreased by treatment with the H1 receptor antagonist mepyramine (0.1 micrometer), and the response to carbachol was blocked by treatment with atropine (0.1 micrometer). Indomethacin (3 micrometer), cimetidine (1 micrometer), propranolol (10 micrometer), and N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ) (4 micrometer) did not alter the differential response of the two strips to histamine and carbachol. The differential response of parenchymal strips with many, few, or no conducting airways and blood vessels was identical, suggesting that the contractile element is alveolar duct smooth muscle or alveolar contractile elements. This differential pharmacologic response in vitro is consistent with the in vivo observation that histamine causes more peripheral airway constriction than does acetylcholine.
Drazen, J. M., S. H. Loring, et al. (1978). "Lung volumes after antigen infusion in the guinea pig in vivo: effects of vagal section." J Appl Physiol 45(6): 957-61.
The effects of intravenous antigen infusion on lung volumes and quasi-static deflationary pulmonary compliance in guinea pigs previously sensitized to ovalbumin were studied in vivo. Ovalbumin infusion significantly increased minimal gas volume to a similar extent in animals with intact or cut vagi. Total lung capacity fell only in animals with intact vagi. Quasi-static compliance fell in both groups of animals, but the fall was significantly greater in animals with intact vagi. These data demonstrate that immediate hypersensitivity reactions alter lung volumes and the elastic properties of the lung by both vagal dependent and vagal independent mechanisms.
Loring, S. H., J. M. Drazen, et al. (1977). "Canine pulmonary response to aerosol histamine: direct versus vagal effects." J Appl Physiol 42(6): 946-52.
Histamine, a potent bronchoconstrictor, has been shown to produce bronchoconstriction both directly and by a vagal reflex. To define the relative roles of direct and reflex effects, we studied the pulmonary response of dogs exposed to increasing doses of aerosol histamine before and after vagal blockade or vagotomy. In addition, the relative contributions of aerodynamically large and small airways to the overall response were determined by the measurement of pulmonary resistance on sulfur hexafluoride-oxygen and helium-oxygen mixtures. Histamine aerosol caused a similar dose-dependent increase in resistance of aerodynamically large and small airways and fall in dynamic compliance. The dose-response relationships were not consistently altered by either vagal blockade or vagotomy. The following variables were found not to alter the experimental results: anesthesia, type of aerosol generator, control of breathing during aerosol exposure, spontaneous breathing vs. controlled ventilation after aerosol exposure, cold block of vagi vs. vagotomy. We conclude that 1) histamine aerosol in dogs causes a local dose-dependent constriction of bronchial smooth muscle, and 2) the vagus nerve played a relatively minor role in the pulmonary response to aerosol histamine in these experiments.
Drazen, J. M., S. H. Loring, et al. (1976). "Validation of an automated determination of pulmonary resistance by electrical subtraction." J Appl Physiol 40(1): 110-13.
An analog computer to determine dynamic pulmonary compliance (C) and pulmonary resistance (R) on a breath-by-breath basis was tested in guinea pigs and dogs. C was determined by dividing volume by transpulmonary pressure at instants of zero flow. R was determined by the method of electrical subtraction at predetermined flows. In both species the computer outputs and the results of direct analysis were in close agreement. In guinea pigs, the device reliably followed the rapid three- to fourfold changes in C and R resulting from histamine infusion. In unanesthetized dogs, the dispersion and mean values of C and R were similar by the two methods.
Drazen, J. M. (1976). "Physiologic basis and interpretation of common indices of respiratory mechanical function." Environ Health Perspect 16: 11-6.
Tests of pulmonary mechanical function may be used in determining the prominent site of pulmonary reaction to intervention. Responses may be localized from a knowledge of changes in lung resistance and compliance. A peripheral airway or parenchymal response is characterized by a decrease in lung compliance. A central airway reaction is characterized by an increase in pulmonary resistance. In mixed reactions both parameters may change. In this communication some of the physiologic determinants of pulmonary resistance and compliance are discussed and examples of localized responses given.
Drazen, J. M., S. H. Loring, et al. (1976). "Distribution of pulmonary resistance: effects of gas density, viscosity, and flow rate." J Appl Physiol 41(3): 388-95.
Theoretical predictions of the distribution of inspiratory viscous pressure loss were made for canine and human pulmonary airways for gases with varying density and viscosity at different pulmonary flow rates. We predicted that in canine or human airways when tracheal flow was turbulent, most of the total calculated pressure loss would be in the first few branchings of the bronchial tree; however when tracheal flow was nearly laminar inspiratory pressure loss would be spread more uniformly along the airways. To test these predictions an airway catheter was used to partition total pulmonary resistance (RL) in five anesthetized dogs. On air the catheter was positioned such that the mean resistance mouthward of the catheter tip (Rc) at a flow of 0.5 1/s was 63% of RL. At the same catheter position Rc was 87% of RL when the dogs were breathing a mixture of 80% sulfur hexafluoride-20% oxygen and resistance was determined at 1.0 1/s. Rc was 50% of RL when the dogs were breathing a mixture of 80% helium-20% oxygen and resistance was determined at 0.25 1/s. Thus altering gas physical properties and flow rates changed the distribution of pulmonary resistance as predicted.
Drazen, J. M., S. H. Loring, et al. (1976). "Localization of airway constriction using gases of varying density and viscosity." J Appl Physiol 41(3): 396-9.
The relationship between the major site of airway constriction and change in total pulmonary resistance while breathing gases of varying density and viscosity was studied in five anesthetized dogs pretreated with atropine. Using an airway catheter, central and peripheral components of pulmonary resistance were measured by forced oscillation. Total pulmonary resistance was measured at 0.5 1/s with lungs air-filled, at 0.25 1/s with the lungs filled with 80% helium-20% oxygen (RL-He), and at 1.0 1/s with 80% sulfur hexafluoride-20% oxygen (RL-SF6). Intravenous histamine infusion resulted in a predominantly peripheral resistance increase as determined by the airway catheter and a much larger percentage increase in RL-He than in RL-SF6. Tracheal banding produced a purely central resistance increase and a greater change in RL-SF6 than in FL-He. These results support theoretical predictions that the predominant site of airways constriction can be determined without on airway catheter by comparing relative changes in total pulmonary resistance using different flow regimes.
Drazen, J. M. and K. F. Austen (1975). "Atropine modification of the pulmonary effects of chemical mediators in the guinea pig." J Appl Physiol 38(5): 834-8.
The actions of histamine, slow-reacting substance of anaphylaxis (SRS-A), Bradykinin, and prostaglandin F2alpha on pulmonary mechanics in the unanesthetized guinea pig were separated into direct and secondary cholinergic airway effects on the basis of alteration of their actions by atropine. The effects of SRS-A (500 and 3,000 units/kg) on compliance were not significantly altered by atropine, while the effects of bradykinin (3.0 and 30 mug/kg) on compliance were decreased only at 3.0 mug/kg by atropine. The effects of both of these agents on resistance were decreased by atropine, suggesting that SRS-A and bradykinin act directly on the peripheral airways and by secondary cholinergic mechanisms on both central and peripheral airways. The effects of histamine (3.0 mug/kg) on both compliance and resistance were abolished by atropine, suggesting an action mainly via cholinergic pathways; while at a higher dose, 9.0 mug/kg, there was both a direct and a cholinergic action. The effects observed 20 sec after the administration of prostaglandin F2alpha (PGF2alpha) were not altered by atropine suggesting a direct action on airways, while both the compliance and resistance changes observed 3-8 min after PGF2alpha were abolished by atropine suggesting that the latter effects were mediated solely by cholinergic mechanisms
Drazen, J. M. and K. F. Austen (1975). "Pulmonary response to antigen infusion in the sensitized guinea pig: modification by atropine." J Appl Physiol 39(6): 916-9.
Alterations in pulmonary conductance, dynamic compliance, respiratory frequency, minute volume, mean arterial pressure, pulse rate, relaxation volume-to-dry weight ratio, and wet-to-dry weight ratio resulting from antigen infusion in sensitized guinea pigs was examined with and without atropine treatment. In untreated animals 3 min after antigen infusion there were significant decreases in dynamic compliance and pulmonary conductance with an increase in relaxation volume-to-dry weight ratio while other parameters were not altered. In atropine-treated animals antigen infusion resulted in a decreased dynamic compliance and an increased relaxation volume-to-dry weight ratio but no significant change in pulmonary conductance. This suggests that the alterations in large and central airway tone resulting from antigen infusion are mediated predominantly by secondary cholinergic mechanisms while peripheral airway effects are mainly noncholinergic.