Body temperature modulates the effect of platelet-activating factor (PAF) on airways responsiveness in the rabbit

The effects of daily bathing on symptoms of patients with bronchial asthma

Background

The influence of bathing in asthma patients is not yet fully known.

Objective

We conducted an observational study to investigate changes in symptoms and their degree by bathing in asthmatic patients.

Methods

A questionnaire focusing on ever experienced bathing-induced symptom changes and their degree, as well as contributing factors, was designed and administered to asthmatic patients in the outpatient department of our institute between January 2012 and November 2013.

Results

Two hundred fifteen cases were recruited. In 60 cases (27.9%), asthmatic symptoms appeared, including 20 cases of chest discomfort (33.3%), 19 cases of cough (31.7%), and 21 cases of wheezing (35.0%). The triggering factors included vapor inhalation (32 cases, 53.3%), hydrostatic pressure on the thorax due to body immersion in the bathtub (26 cases, 43.3%), and sudden change of air temperature (16 cases, 26.7%). Thirty-eight cases (17.7%) experienced improvement in active asthmatic symptoms by bathing. Vapor inhalation was the most common contributing factor (34 cases, 89.5%), followed by warming of the whole body (13 cases, 34.2%). There was no relationship between asthma severity and the appearance of bathing-induced symptoms or improvement of active asthmatic symptoms by bathing.

Conclusion

The effects of bathing in asthmatic patients widely differed from patient to patient and their etiology includes several factors. For those who suffer from bathing-induced asthma symptoms, preventive methods, such as premedication with bronchodilators before bathing, should be established. This study is registered in the University Hospital Medical Information Network (UMIN) clinical trials registry in Japan with the registration number UMIN000015641.

Bimodal effect of platelet-activating factor (PAF) on airways responsiveness in the rabbit

The role of platelet-activating factor (PAF) to increase airways responsiveness is unclear. Since PAF has unusual dose-response characteristics in vitro, this study investigated the effects of different doses or concentrations of PAF given by intravenous and aerosol administration in anesthetized rabbits. Aerosol PAF caused a dose-dependent decrease in SGL. Intravenous administration of PAF was associated with thrombocytopenia and neutropenia, whereas aerosol administration of PAF did not alter the numbers of circulatory cells. With either administration, no inflammatory cells were recovered by lavage nor was there evidence of a gross inflammatory process within the lung. Furthermore, there was no evidence of a late asthmatic response. Intravenous PAF caused a bimodal change in airways responsiveness with a significant increase in the effective concentration causing 50% of the maximal change in SGL (EC50SGL) at low doses (0.06-06 micrograms/kg h-1) and a significant decrease in EC50SGL (an increase in responsiveness) at higher doses (1.2-2.4 micrograms/kg/h-1). Aerosol PAF decreased EC50SGL significantly at the higher doses (100-250 micrograms). These changes in EC50SGL, after both administrations, were still apparent at 3 1/2 and 4 h. In conclusion PAF has a dose-dependent, biphasic, and persistent effect on airways responsiveness, which may be independent of circulating inflammatory cells.

Inhaled budesonide fails to inhibit the PAF-induced increase in plasma leukotriene B4 in man

1. We studied the ability of inhaled budesonide to modulate PAF-induced acute effects in nine healthy nonsmoking volunteers. Responses in inflammatory cells and mediators in peripheral blood as well as in pulmonary function and circulation were monitored. 2. Inhalation of increasing doses of PAF (total cumulative dose of 500 micrograms) caused a rapid and profound decrease in circulating white blood cells, especially in granulocytes (P less than 0.01), which was turned to an increased number of these cells (P less than 0.05, P less than 0.025, respectively) in the blood samples taken 8 min after completion of the PAF challenge. No changes in the circulating platelets or their thromboxane production were found. Plasma concentrations of histamine or methylhistamine remained unchanged during PAF-inhalation, while plasma LTB4 tripled from the baseline level at 10 min (P less than 0.0005) and was returned to the pre-PAF value at 60 min. 3. PAF inhalation induced a bronchial obstruction (P less than 0.025), but no bronchial hyperresponsiveness to methacholine was found in any of our subjects when measured 24 h after the PAF challenge. Furthermore, PAF caused a decrease in systolic blood pressure (P less than 0.05). 4. Budesonide pretreatment of 400 micrograms twice daily during the preceding 5 days had no effect on any PAF-induced events measured in our study. That fact may also contradict the role of bronchial resident or alveolar cells as a source of the PAF-induced LTB4 burst in plasma. 5. We conclude that in healthy volunteers inhaled PAF induces a marked increase in plasma LTB4, which is not inhibited by inhaled budesonide.(ABSTRACT TRUNCATED AT 250 WORDS)