PubMed · 11208661
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V Popa. 2001. ATS guidelines for methacholine and exercise challenge testing.. https://doi.org/10.1164/ajrccm.163.1.16310b
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Chronic obstructive pulmonary disease (COPD) is characterized by chronic inflammation in the airways, parenchyma and vessels, which can cause a structural remodeling with increased fibrosis that narrows and fixes the airway lumen. Transforming growth factor-beta1 (TGF-beta1), a multifunctional growth factor, was reported to be increased in the airways of COPD patients. In this study, we hypothesized that polymorphisms in the TGF-beta1 gene would be associated with an accelerated rate of decline of forced expiratory volume in 1s (FEV(1)). Three polymorphisms, -509 (C-->T), +869 (T-->C) and +915 (G-->C), located in TGF-beta1 gene were genotyped. We determined the prevalence of these polymorphisms in 590 continuing smokers who had the fastest (n=283) and slowest (n=307) rate of decline of lung function from the NHLBI Lung Health Study. There was no association between these TGF-beta1 polymorphisms and the rate of decline of FEV(1), but in a post-hoc analysis the genotype distribution at +869 was significantly different between high and low responders to methacholine (P=0.04). These data suggest that the T-C polymorphism at position +869 in the TGF-beta1 gene contributes to airway hyperresponsiveness, but not to rapid decline of lung function.
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Methacholine chloride is a powerful cholinergic bronchoconstrictor agent used during bronchial airway hyper-responsiveness diagnosis. Methacholine is susceptible to hydrolysis in aqueous solutions in acetic acid and beta-methylcholine. In the present work, kinetics of hydrolysis with different solvents (water and phosphate-buffered saline (PBS) pH 7.4) at different temperatures have been studied using a newly developed high-performance liquid chromatography. At 4 degrees C, kinetic determination of hydrolysis in methacholine chloride solutions (50 mg/ml) shows no hydrolysis in either aqueous or phosphate-buffered solutions over a 40-day period. At 30 degrees C, concentration of unbuffered methacholine chloride solutions remained unchanged, but buffered methacholine chloride solutions have degradation up to 5.5% over a 40-day period. At 40 degrees C, concentration of unbuffered methacholine chloride has degradation up to 5% and buffered methacholine chloride solutions have degradation up to 10% over a 40-day period. Methacholine chloride solutions are susceptibly to be used in hospital pharmacy at different concentrations. We have studied pH and osmolality for methacholine solutions prepared with different diluents potentially used in hospital pharmacies, i.e. deionized water, 0.9% NaCl and PBS pH 7.4. We have demonstrated that methacholine solutions prepared with deionized water at 50 mg/ml and diluted with PBS pH 7.4 from 5 to 40 mg/ml are isoosmotic and potentially available for inhalation tests to measure non-specific bronchial hyper-responsiveness.