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Biomedical subjects

M Chatham

Publications and source records attributed to M Chatham.

5 recordsLinked to original sources
PubMed1985

Inhibitability and enhanceability of basophil histamine release in asthmatic and normal subjects.

Circulating human basophils contain histamine, a potent mediator of inflammation. Previous in vitro studies have shown that histamine 'releasability' in asthmatic subjects differs from normal subjects but have not evaluated possible differences in the immunopharmacological control of the release of this mediator which might account for these differences. The purpose of the present study was to examine the immunopharmacologic control of basophil histamine release in 14 asthmatics and 10 normal subjects who were characterized by pulmonary function tests, allergic status (skin tests and serum IgE levels) and nonspecific airways reactivity to methacholine and histamine. Basophils were stimulated with anti-IgE, and the inhibitory effects of the H2 agonist, dimaprit, and dibutyryl cyclic AMP (dbcAMP), as well as the enhancing properties of 5-hydroperoxyeicosatetraenoic acid (5-HPETE) and indomethacin on the modulation of histamine release, were investigated. Although no statistically significant differences were seen in the percent histamine release triggered by anti-IgE in these two groups, enhancement of histamine release by 5-HPETE was more consistent in the asthmatic subjects (10 of 10) than in control subjects (6 of 8). The percent increase in histamine release produced by 5-HPETE in asthmatic subjects averaged 3.9 +/- 1.3% using 0.03 micrograms anti-IgE/ml and 4.8 +/- 3.2% using 0.1 microgram anti-IgE/ml (p less than 0.002, Wilcoxon's signed rank test), and averaged 3.0 +/- 4.3 and 3.1 +/- 5.3%, respectively, in control subjects (p greater than 0.10).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1982

CO concentration-dependent changes in pulmonary diffusing capacity in humans.

Steady-state CO pulmonary diffusing capacity (DLCO) was measured at different inspired CO concentrations in seven males and one female during light treadmill exercise. As the CO level is increased. DLCO increases, reaches a maximum at an end-tidal CO concentration of approximately 100 ppm, and then decreases. The maximum DLCO is up to twice as large as the DLCO measured at an inspired CO concentration of approximately 1,780 ppm. These results are consistent with the presence of saturation kinetics, one of the basic properties of carrier-mediated transport systems. A similar relationship between DLCO and CO concentration was found in previous studies of mechanically ventilated dogs. Thus there is evidence for carrier-mediated transport of CO in the lungs of both humans and dogs.

Adult↗
PubMed1982

A screening test for airways reactivity. An abbreviated methacholine inhalation challenge.

A screening test to measure nonspecific airways reactivity was developed and compared to a standard methacholine inhalation challenge in 13 asthmatic patients and ten normal control subjects. The screening challenge consisted of one deep breath, then four breaths of a 5 mg/ml methacholine solution followed by one and four breaths of 25 mg/ml of methacholine. Subjects with a history of wheezing received the 5 mg/ml of methacholine first while those without a history of asthma began the challenge at the 25 mg/ml methacholine concentration. Spirometric test were employed and the challenge was terminated when FEV1 fell 20 percent from baseline. The standard methacholine challenge used a dosimeter and all subjects took five breaths of saline solution followed by seven increasing concentrations of methacholine. Dose response curves were constructed and the provocation dose of methacholine that caused a 20 percent fall in FEV1 was calculated for each protocol. Results of the screening methacholine challenge correlated with those obtained from the more lengthy standard protocol (r = 0.94), and correctly identified levels of airways reactivity in asthmatic patients and normal subjects. The abbreviated protocol was rapid (6-12 min), safe, and inexpensive. Since the equipment is readily available and easy to transport, it could be used at sites outside the hospital as a screening test for nonspecific airways reactivity.

Adult↗