The value of determining the slope of the histamine dose-response curve, in addition to the histamine provocation concentration producing a 20% reduction in FEV1 (PC20-FEV1), was assessed by analysis of histamine dose-response curves in 40 patients selected as having a wide range of increased non-specific bronchial responsiveness to inhaled histamine. The histamine dose-response curves were fou...

Inhaled adenosine 5'-monophosphate (AMP) causes bronchoconstriction in atopic asthma, probably after in vivo conversion to adenosine. It has been suggested that adenosine potentiates preformed mediator release from mast cells on the mucosal surface of the airways by interacting with specific purinoceptors, without affecting the release of newly generated mediators. The airway response of nine n...

Background—It is desirable to prescribe the minimal eVective dose of inhaled steroids to control asthma. To ensure that inflammation is suppressed whilst using the lowest possible dose, a sensitive and specific method for assessing airway inflammation is needed. Methods—The usefulness of exhaled nitric oxide (NO), sputum eosinophils, and methacholine airway responsiveness (PC20) for monitoring ...

Episodic wheezing associated with viral infections of the upper respiratory tract (URT) is a common problem in young children but also occurs in adults. It is hypothesized that an experimental infection with human coronavirus (HCoV), the second most prevalent common cold virus, would cause lower respiratory tract (LRT) changes in adults with a history of viral wheeze. Twenty-four viral wheezers...

To study the temporal relation between the peak of circadian variation of bronchial responsiveness and the trough of circadian variation of bronchial caliber, we performed seven inhalation challenges with histamine at 4-h intervals in six stable asthmatic children aged eight to ten years. Bronchial responsiveness was expressed as PC20. Coefficient of variation of baseline FEV1 within the study ...

We investigated whether an increase in transcutaneous electromyographic (EMG) activity of the diaphragm and intercostal muscles corresponds with the concentration of histamine that induces a 20% fall in the forced expiratory volume in one second (FEV1; PC20). Eleven asthmatic children (mean age 11.9 yr) were studied after they were given histamine challenge. EMG activity at PC20 or at the highe...

BACKGROUND/AIMS We sought to increase our understanding of the rhinitis-asthma relationship and improve strategies for the treatment of patients with these diseases. The aim of this study was to identify a connection between upper airway inflammation and lower airway responsiveness. METHODS We counted eosinophils on nasal smears, and performed spirometry, allergic skin tests, and methacholine...

Findings In athletes with AHR, the PC20 (expressed as the mean of double concentrations (DC) ± standard error) was 0.7 ± 1.2 DC lower when MIT followed EVH (p = 0.015), while there was no significant difference in athletes without AHR (-0.4 ± 0.8 DC) nor in control subjects (0.4 ± 0.7 DC). When grouping subjects based on the EVH response, those with a positive response (FEV1 fall ≥ 10%) had a m...

In a recent editorial (May 1993; 48: 470-3) Drs van Schayck and van Herwaarden present a surprisingly ambivalent account of the effects of agonist treatment on airway responsiveness. Their conclusion that agonists have an unimportant effect on responsiveness appears to be based on recent analyses of data from their own study.' However, a thorough review of the studies discussed by van Schayck a...

The manner in which a cigarette is smoked varies considerably between individuals and may be an important determinant of the altered bronchial reactivity observed in cigarette smokers. Twenty smokers were examined to determine the relationship between cigarette smoke inhalation patterns and bronchial reactivity. Inhalation patterns were measured non-invasively with a respiratory inductive pleth...