BACKGROUND A number of studies have suggested that diurnal variation in airways responsiveness underlies the circadian rhythm of ventilatory function in asthma. Measurements of airways responsiveness are therefore often performed at standardised times in order to avoid this possible effect, but this is not practical for epidemiological studies. Refractoriness to methacholine has also been repor...

Acetylcholine released from cholinergic nerves is involved in heat loss responses of cutaneous vasodilation and sweating. K(+) channels are thought to play a role in regulating cholinergic cutaneous vasodilation and sweating, though which K(+) channels are involved in their regulation remains unclear. We evaluated the hypotheses that 1) Ca(2+)-activated K(+) (KCa), ATP-sensitive K(+) (KATP), an...

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...

Increased production of superoxide anion may contribute to impaired bioactivity of endothelium-derived nitric oxide in hypertension. Ascorbic acid is capable of scavenging superoxide anion; however, experimental studies have shown that high physiological concentrations (>1 mmol/L) of ascorbic acid are required to prevent superoxide-mediated vascular dysfunction. To seek kinetic evidence that su...

OBJECTIVE To compare airway responsiveness to methacholine, cycle ergometer exercise and free running in children with intermittent asthma. METHODS A randomized study was conducted with 30 children of both genders with intermittent asthma. Each child was submitted to challenge testing on three separate days, in random order: a) Methacholine challenge using a dosimeter; b) Exercise challenge t...

STUDY OBJECTIVES Validation of test-shortening procedures for the 2-min tidal breathing methacholine challenge method. DESIGN Retrospective chart review. SETTING Tertiary-care university clinical pulmonary function laboratory. PATIENTS One thousand subjects aged 10 to 85 years (mean +/- SD, 44.5 +/- 16.0 years), 44.5% male, referred for methacholine challenge. INTERVENTION Two-minute ti...

The forced oscillation technique (FOT) and multiple-breath nitrogen washout (MBNW) are noninvasive tests that are potentially sensitive to peripheral airways, with MBNW indexes being especially sensitive to heterogeneous changes in ventilation. The objective was to study methacholine-induced changes in the lung periphery of asthmatic patients and determine how changes in FOT variables of respir...

study are relevant, I believe that the design of the study was not adequate to answer these questions. First, all patients were on NM for w3 months and one patient even for 70 months, whereas they trained only for 1 day on FFM. In our centre (Dept of Pulmonary Diseases/ Home mechanical ventilation, University Hospital Groningen, Groningen, The Netherlands), patients routinely need more time (y7...

The role of airway inflammation in the pathogenesis of asthma in childhood is uncertain. In the present study, 27 atopic and nonatopic children aged 7-9 yrs who had > or = 5 episodes of wheeze and symptoms of exercise-induced asthma (EIA) in the previous 12 months, performed a methacholine challenge and exercise test on separate days at monthly intervals. The subjects had not received oral or i...