A characteristic feature of airway smooth muscle is its relative sensitivity to relaxant effects of beta adrenergic agonists when contracted by inflammatory mediators, such as histamine, vs. resistance to these relaxant effects when contracted by muscarinic agonists. Because contractions presumably depend upon the hydrolysis of membrane phosphoinositides (PI) and the generation of inositol phos...

OBJECTIVE To determine the extent to which thin-section and volumetric threedimensional CT can depict airway reactivity to bronchostimulator, and to assess the effect of different airway sizes on the degree of reactivity. MATERIALS AND METHODS In eight dogs, thin-section CT scans were obtained before and after the administration of methacholine and ventolin. Cross-sectional areas of bronchi a...

STUDY OBJECTIVE We evaluated whether aging may produce changes in bronchial hyperresponsiveness, risk of enhanced bronchoconstriction, and changes of bronchoconstriction perception. SETTING Each subject underwent a methacholine bronchial challenge. Methacholine challenge was stopped when one of the following conditions occurred: (1) plateau of bronchoconstriction; (2) decrease of FEV(1) > 40%...

In a previous study on 27 patients with chronic bronchitis we found that only three developed bronchoconstriction in response to hyperventilation of cold, dry air despite an increased responsiveness to methacholine inhalation. We therefore investigated bronchial responsiveness to hyperventilation with cold, dry air and methacholine in 27 patients with stable asthma who had a similar range of ba...

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...

Enhanced negative volume dependence of airway resistance is associated with bronchoconstriction in tracheostomized paralysed open-chest animals. Significant upper airways responses may be associated with bronchoconstriction and could thereby alter the pattern of volume dependence in spontaneously breathing subjects. The aim of the study was to test whether volume dependence of respiratory resis...

Remote vasodilation caused by arteriolar microapplication of acetylcholine cannot be completely attributed to passive cell-cell communication of a hyperpolarizing signal. The present study was undertaken to ascertain whether a neural component may be involved in the remote response. In the cheek pouch of anesthetized hamsters, methacholine (100 microM) was applied to the arteriole by micropipet...

The European Respiratory Society guidelines on bronchial provocation testing have proposed time-saving procedures, which may lead to unwanted exaggerated responses. The frequency and determinants of exaggerated bronchoconstriction in response to methacholine inhalation testing in clinical and epidemiological settings have not been assessed. The authors evaluated: 1) the prevalence of exaggerate...

BACKGROUND Some epidemiological studies have shown that increased iron stores are associated with increased cardiovascular events. Redox-active iron may contribute to lipid peroxidation, endothelial cell activation, and generation of reactive oxygen species (especially hydroxyl radical, via Fenton chemistry). Increased oxidative stress is associated with impaired action of endothelium-derived n...

Bronchial reactivity is being measured with increasing frequency in epidemiological studies, but there debate continues about the relative merits of the different methods used to measure reactivity, particularly for subjects with no previous experience of reactivity testing as is the case in epidemiological studies. Repeatability is likely to improve with practice, and laboratory based studies ...