Biomedical subjects

D Bartenfelder

Publications and source records attributed to D Bartenfelder.

3 recordsLinked to original sources

PubMed1990

Decrease in xenon clearance during response to cold, dry air: problems of interpretation.

In order to increase our understanding of the nasal response to cold, dry air (CDA), we studied changes in xenon clearance as an indicator of nasal blood flow. Eight individuals previously shown to respond to CDA had measurements of xenon clearance made in the left inferior turbinate before, during, and after a 15-minute exposure to either CDA (-7 degrees C to 0 degrees C, less than 10% relative humidity) or room air. The half-life in seconds for xenon clearance on the day when CDA was inhaled was 56 +/- 6, 41 +/- 5, and 110 +/- 31, before, during, and 10 minutes after challenge, respectively. On the control day, with subjects breathing room air, the equivalent measurements of half-life in seconds were 54 +/- 8, 41 +/- 6, and 42 +/- 4, respectively. Xenon clearance was prolonged significantly (p less than .01) after exposure to CDA during the clinical response. The interpretation of the change in xenon clearance as an indicator of nasal blood flow is discussed.

Air↗

PubMed1986

Theophylline reduces histamine release during pollen-induced rhinitis.

In an attempt to understand how theophylline achieves its in vivo therapeutic effect, a double-blind crossover study of the effect of theophylline on the immediate response of the upper airways to challenge with antigen was performed. Ten subjects with allergic rhinitis were challenged with increasing doses of antigen extract, and their responses were assessed by counting the number of sneezes and measuring the level of histamine, N-alpha-p-tosyl-L-arginine-methyl ester-esterase activity, and kinin in nasal secretions. One-week premedication with theophylline led to serum levels in the therapeutic range (8 to 21 micrograms/ml). There were significant reductions in both the physiologic response to antigen challenge and the appearance of mediators in secretions after drug administration as compared to placebo. These data suggest that theophylline, at therapeutic blood levels, achieves at least part of its in vivo efficacy by reducing the release of histamine and other mediators from mast cells/basophils.

Histamine Release↗

PubMed1985

Theophylline reduces the response to nasal challenge with antigen.

A nasal challenge model of allergic rhinitis was used to determine if pretreatment with oral theophylline reduces histamine release in vivo. Ten subjects were entered into a double-blind, cross-over trial. The results showed that both the physiologic response (sneezing) (p = 0.02) and the amount of mediators (histamine, kinins, toluene sulfonyl arginine methyl ester esterase activity) (p less than 0.01 for all) released into nasal secretions were significantly reduced after one week of pretreatment with theophylline. At the time of challenge, the serum concentrations of theophylline were between 8 and 22 micrograms/ml. It is speculated that the ability of theophylline to block the clinical response to antigen challenge and to decrease the release of mast cell mediators contributes to its clinical efficacy in the treatment of asthma.

Adolescent↗