BACKGROUND Considerable, unexamined controversy exists surrounding the use of the highest vs the lowest FEV(1) for calculating the provocative concentration causing a 20% fall in FEV(1) (PC(20)) during direct bronchoprovocation challenges. OBJECTIVE To compare the PC(20) calculated using the lowest FEV(1) post-diluent and post-histamine/methacholine vs the PC(20) calculated using the highest ...

The effect of increasing intravenous doses of theophylline and enprofylline, a new xanthine derivative, on bronchial responsiveness to methacholine was studied in eight asthmatic patients. Methacholine provocations were carried out on three days before and after increasing doses of theophylline, enprofylline, and placebo, a double blind study design being used. Methacholine responsiveness was d...

BACKGROUND Little is known regarding mechanistic and phenotypic differences between cough variant asthma (CVA), presenting with a chronic cough as the sole symptom that responds to bronchodilators, and classic asthma with wheezing during methacholine inhalation. Here we reported airway sensitivity, airway reactivity, and as the main concern, the appearance of cough and wheezes during methacholi...

BACKGROUND/AIMS Many patients with aspirin-induced asthma have severe methacholine airway hyperresponsiveness (AHR), suggesting a relationship between aspirin and methacholine in airway response. This study was performed to determine whether methacholine AHR affects the response of asthmatics to inhaled aspirin. METHODS The clinical records of 207 asthmatic patients who underwent inhalation c...

Current asthma is often diagnostically excluded by the presence of normal bronchial responsiveness. We report on a TDI-induced occupational asthma patient with normal bronchial responsiveness. He had suffered from shortness of breath during and after TDI exposure for several months. His initial methacholine bronchial challenge test showed a negative response. The bronchoprovacation test with TD...

BACKGROUND The standard 2-min tidal breathing methacholine challenge utilizes 3 mL to produce an output of 0.26 mL per 2 min, resulting in a substantial amount of methacholine being discarded. OBJECTIVE To develop a method with reduced methacholine waste and to compare it to the standard method. METHODS Twelve subjects with mild, well-controlled asthma volunteered for this investigation. Th...

BACKGROUND Cough in the patients with cough variant asthma is triggered by bronchoconstriction, which responds to bronchodilator therapy. Following airway narrowing induced by inhaled methacholine, deep inspiration (DI) causes dilation of the airways in both asthmatic and non-asthmatic subjects. The aim of the present study was to investigate the relationship between bronchodilator effect of DI...

The effects of inhaled platelet activating factor were compared with those of inhaled methacholine (control) on airway calibre, airway responsiveness to methacholine and isoprenaline, and circulating cells in eight subjects with mild, stable asthma. Platelet activating factor was given in six doses at 15 minute intervals and airway response measured as change in partial expiratory flow at 30% o...

Introduction: In the present study, the prophylactic effect of vitamin C, as a potent anti-oxidant, on tracheal responsiveness to methacholine and ovalbumin, bronchoalveolar lavage fluid white blood cell (WBC) count and differential count, and also lung pathology in chronic obstructive pulmonary disease (COPD) -guinea pigs (cigarette exposed guinea pigs) were examined. In addition, the relax...

BACKGROUND Recent in vitro and in vivo studies in animals have suggested that ambient oxygen tension may influence airway responsiveness to bronchoconstrictor stimuli. These observations may have relevance to the management of acute exacerbations of asthma. The present studies were designed to examine the influence of inspired oxygen tension (Fio2 1.0, 0.21, 0.15) on methacholine-induced bronch...