BACKGROUND Exposure to ammonium persulfate (AP) has been reported to be the main cause of occupational asthma in hairdressers. The aim of this study is to assess how long the asthmatic response to AP can be induced after dermal sensitization in a mouse model. METHODS BALB/c mice received dermal applications of AP or dimethylsulfoxide (DMSO) (control) on days 1 and 8. They then received a sing...

Passive dry-powder inhalers (DPIs) have been developed as an alternative to pressurised metered-dose inhalers (pMDIs) to improve aerosol delivery on inhalation and eliminate the need for propellants. However, new DPI formulations of generic drugs must be rigorously compared with conventional pMDI therapy. This randomised, double-blind, double-dummy, placebo-controlled, seven-way crossover study...

Background: The methacholine bronchial provocation test is a useful tool for evaluating asthma in patients with normal or near normal baseline lung function. However, the sensitivity of this test is 82∼92% at most. The purpose of this study is to evaluate the clinical usefulness of FEF25-75% in identification of airway hyperresponsiveness in patients with suspected asthmatic symptoms. Methods: ...

To investigate whether the effects of nifedipine on methacholine induced broncho-constriction could impair pulmonary gas exchange in bronchial asthma a randomised, double blind, crossover study in 13 symptom free asthmatic subjects was designed. Each patient underwent a methacholine bronchial challenge test on two separate days one week apart, after having either oral nifedipine (20 mg thrice d...

A 30-year-old Caucasian man presented to the pulmonary function laboratory for a methacholine challenge test. Following inhalation of the final dose of methacholine, the forced expiratory volume in 1 s (FEV1) was 8% below baseline. However, the patient complained of chest tightness and dyspnea, similar to the symptoms he experienced after running. Repeat specific airway conductance was found to...

The bronchoconstrictor potency of inhaled methacholine is widely used to assess airway responsiveness. However, evidence has accumulated that methacholine inhalation challenge may lead to an inflammatory response in the lower respiratory tract. We therefore compared cellular, leukotriene and prostanoid profiles in bronchoalveolar lavages (BAL) obtained five hours after methacholine challenge to...

We examined the hypothesis that a forced expiratory volume in one second (FEV1) manoeuvre (and the preceding deep inhalation) before inhalation of methacholine might influence FEV1 measured after methacholine, if the time between measurements was short. Six to nine healthy subjects inhaled a single dose of methacholine, known to cause about 20% decrease in FEV1, on different days in different t...

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 A low serum vitamin D level may represent a marker of other perplexing factors that may lead to increased asthma prevalence and severity. Our aim was to assess the correlation between vitamin D levels and asthma and allergy markers in a subgroup of children with fewer confounding factors. METHODS Non-obese children (6-18 y old) with asthma who were not receiving anti-inflammatory t...

We investigated the hypothesis that prior airway muscarinic receptor stimulation (with aerosolized methacholine) would modify the bronchoconstrictor response to histamine, which is, in part, vagally mediated. On four different experiment days, the following combinations of methacholine and histamine inhalation challenges were performed in 15 subjects (nine normal and six asthmatic) in a random ...