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Biomedical subjects

R Brown

Publications and source records attributed to R Brown.

At least 775 records · Page 43Linked to original sources
PubMed1979

Effects of environmental oxidant stressors on individuals with a G-6-PD deficiency with particular reference to an animal model.

Individuals with a G-6-PD deficiency have long been known to be at increased risk to experience acute hemolysis following exposure to elevated levels of certain oxidant drugs and industrial chemicals. However, the recognition of enhanced susceptibility to environmental (or ambient) pollutants has generally not been considered. Recent theoretical studies have suggested that elevated levels of ambient ozone may be an etiologic factor in the onset of acute hemolysis in the G-6-PD deficient individual. Furthermore, the proposed usage of either chloramines or chlorine dioxide as replacements for chlorine for the disinfection of drinking water should be investigated with respect to their potential adverse effects of individuals at increased risk to oxidant stressors. In order to test these theoretical associations, two mouse strains, one with low and the other with high levels of G-6-PD activity in their red blood cells are being investigated to determine if they simulate human G-6-PD deficient and normal individuals, respectively. Preliminary results indicate that the mouse strain with low G-6-PD activity is markedly more susceptible to sodium chlorite than mice of the high G-6-PD strain. This differential susceptibility to sodium chlorite toxicity between the high and low G-6-PD mouse strains suggests that further research designed to validate the efficacy of this mouse model as a predictor of the human situation is warranted.

Air Pollutants↗
PubMed1978

Bovine auto-immune haemolytic anaemia.

A six-months-old heifer died within two days of showing signs of anaemia and dyspnoea. The death was attributed to autoimmune haemolytic anaemia (AHA) because of auto-agglutination which increased on Coomb's testing and the presence of antibovine IgG on the erythrocyte surfaces.

Anemia, Hemolytic, Autoimmune↗
PubMed1978

Fetal hyperinsulinism in rhesus isoimmunization.

Analyses of peritoneal ascitic fluid obtained prior to intrauterine transfusion show that some babies with severe rhesus isoimmunization develop raised insulin levels up to a month before delivery. The glucose content of fetal ascitic fluid is usually only about 10 mg. per 100 ml. less than the glucose content of maternal plasma and there is no evidence that this relation is influenced by the fetal or maternal insulin level. The electrolyte content of fetal ascitic fluid is very similar to that of maternal plasma, but fluid from babies with hyperinsulinism has an unusually high calcium content.

Ascitic Fluid↗
PubMed1978

Effects of prostaglandin F2alpha on lung mechanics in nonasthmatic and asthmatic subjects.

Prostaglandins have been implicated as secondary pharmacologic mediators in allergic bronchial asthma. We have studied the effects of the intravenous infusion of prostaglandin F2alpha (PGF2alpha) on pulmonary mechanics in nonasthmatic and asthmatic volunteers. Before and during the infusion, measurements were made of total lung capacity and its subdivisions, static deflational transpulmonary pressure-volume relationships (PV), and maximal expiratory flow-volume curves with air and after a washing of an 80% helium-20% oxygen mixture. In both groups, PGF2alpha caused significant decreases in vital capacity and maximal flow and increases in residual volume. There were not significant differences between groups in either the absolute magnitude or the percent change in the variables, a result which may have been due to the similarity of the pulmonary mechanics in both groups prior to infusion. Changes in density dependence were bidirectional in both groups, indicating that relative contributions of large and small airways to flow limitation changed differently among individuals. The single between-group difference in responses noted was a leftward shift of the PV curve in the asthmatics, suggesting recoil of the lung which occurs in asthma.

Adult↗
PubMed1978

Influence of abdominal gas on the Boyle's law determination of thoracic gas volume.

In a body plethysmograph we have demonstrated differences in total lung capacity (TLC) derived from panting maneuvers performed at different levels in the vital capacity. In almost all cases, the discrepancies were due to the magnitude of the abdominal gas volume (AGV) and the relative magnitude of abdominal and thoracic pressure swings during the panting mandeuver. When panting was performed at functional residual capacity (FRC), the effect of AGV compression on the determination of thoracid gas volume (TGV) was small. Of 11 individuals studied 2 were known to have mild asthma. Compression and decompression of AGV appeared to be an insufficient explanation for discrepancies in derived TLC's in these two, suggesting that other as yet unidentified factors may influence the plethysmographic determination of TGV.

Gases↗
PubMed1978

Problems in the plethysmographic assessment of changes in total lung capacity in asthma.

We studied the effect of abdominal gas compression on plethysmographically determined total lung capacity (TLC) in asthmatic patients before, during, and after treatment of induced bronchospasm. TLC was derived from panting maneuvers near residual volume, at functional residual capacity, and near TLC. Significant differences among these "derived TLC" values increased significantly during bronchospasm. Whether or not TLC appeared to increase, and by how much, depended on the level of the vital capacity from which it was derived. Individual increases in TLC during bronchospasm could not be explained by increases in abdominal gas volume or in the extent to which it was compressed and decompressed during panting. We postulate that during the Boyle's Law panting maneuver, pleural, and therefore alveolar, pressure swings may be nonhomogeneous and greater over lung regions subtended by closed airways than over regions in communication with the mouth. This would result in an underestimation of alveolar pressure swings as measured at the mouth and an overestimation of thoracic gas volume, and would account in large part for the observed increase in discrepancies between the "derived TLC" values in asthma as well as the dependence of apparent TLC changes on the level of the VC at which the panting maneuver is performed.

Asthma↗
PubMed1977

The blue baby.

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Brain Diseases↗