BACKGROUND Asthma-like symptoms are frequent in overweight and obesity, but the mechanism is unclear when airway hyperresponsiveness (AHR) is lacking. In this study, we focused on obese women with a clinical suspicion of asthma but negative methacholine challenge and tested distal airway hyperreactivity, explored by Forced Vital Capacity dose-response slope (FVC DRS). OBJECTIVE To question AH...

BACKGROUND The definition or diagnosis of asthma is a challenge for both clinicians and epidemiologists. Symptom history is usually supplemented with tests of bronchial hyperresponsiveness (BHR) in spite of their uncertainty in improving diagnostic accuracy. METHODS To assess the interrelationship between respiratory symptoms, BHR, and clinical diagnosis of asthma, the respiratory symptoms of...

BACKGROUND Guidelines for the 2-min tidal-breathing and the five-breath dosimeter methods for methacholine challenge have recently been published by the American Thoracic Society (ATS). Although subjects are exposed to twice as much aerosol at any given concentration during the tidal-breathing method compared to the dosimeter method, they were thought to give equivalent results. OBJECTIVE To ...

Direct bronchoprovocation challenges (eg, methacholine), which act directly on a specific airway smooth muscle receptor, are the most commonly performed challenge tests. Cut points have been arbitrarily selected to give high sensitivity and negative predictive values. In subjects with clinically current symptoms (within a few days) who inhale methacholine without deep inhalations, a normal meth...

A 29-year-old man had a persuasive history of respiratory illness following exposures to methylene diphenyl diisocyanate (MDI). He was evaluated by measuring bronchial reactivity to methacholine, both before and after controlled laboratory exposures to MDI. Despite evidence of progressive declines in FEV1 with increasing (but subirritant) doses of MDI on three consecutive days, there was no bro...

UNLABELLED Exhaled nitric oxide (FE(NO)) has been used as a marker of asthmatic inflammation in non-occupational asthma, but some asthmatics have a normal FE(NO). In this study we investigated whether, normal FE(NO) variants have less reactivity in methacholine challenge and smaller peak expiratory flow (PEF) responses than high FE(NO) variants in a group of occupational asthmatics. METHODS W...

Angiotensin II levels are elevated in patients with acute severe asthma. In addition, intravenous angiotensin II causes bronchoconstriction in mild asthmatic patients. In the present study, we examined the effects of this hormone on bronchi in vitro and its interaction with the cholinergic agonist methacholine both in vivo and in vitro. Contractions of rings of human bronchi were measured isome...