Showing papers by "Gary M. Brittenham published in 1992"

Iron overload in Africa: Interaction between a gene and dietary iron content

Abstract: Background and Methods. In contrast to hemochromatosis, which in white populations is inherited through a gene linked to the HLA locus, iron overload in sub-Saharan Africa is believed to result solely from increased dietary iron derived from traditional home-brewed beer. To examine the hypothesis that African iron overload also involves a genetic factor, we used likelihood analysis to test for an interaction between a gene (the hypothesized iron-loading locus) and an environmental factor (increased dietary iron) that determines transferrin saturation and unsaturated iron-binding capacity. We studied 236 members of 36 African families chosen because they contained index subjects with iron overload. Linkage to the HLA region was tested with use of lod scores. Results. In the index subjects, increased iron was present in both hepatocytes and cells of the mononuclearphagocyte system. Among family members with increased dietary iron due to the consumption of traditional beer, transferrin saturation in...

Effect of iron chelation therapy on recovery from deep coma in children with cerebral malaria

Abstract: Background. Cerebral malaria is a severe complication of Plasmodium falciparum infection in children, with a mortality rate of 15 to 50 percent despite antimalarial therapy. Methods. To determine whether combining iron chelation with quinine therapy speeds the recovery of consciousness, we conducted a randomized, double-blind, placebo-controlled trial of the iron chelator deferoxamine in 83 Zambian children with cerebral malaria. To be enrolled, patients had to be less than six years old, have P. falciparum parasitemia, have normal cerebrospinal fluid without evidence of bacterial infection, and be in a coma from which they could not be aroused. Deferoxamine (100 mg per kilogram of body weight per day, infused intravenously for 72 hours) or placebo was added to standard therapy with quinine and sulfadoxine—pyrimethamine. The time to the recovery of full consciousness, time to parasite clearance, and mortality were examined with Cox proportional-hazards regression analysis. Results. The rate of re...

Salivary testosterone concentration of Aymara men native to 3600 m.

Abstract: SummaryThis paper explores the possibility that variation in the normal physiological range of testosterone concentration modulates men's adaptation to hypobaric high-altitude hypoxia through stimulating haemoglobin production and/or causing respiratory disturbances and exacerbated hypoxaemia during sleep. These effects of testosterone are observed clinically at sea level and have potentially opposing consequences at high altitude, the former perhaps enhancing and the latter diminishing the effectiveness of adaptations to hypoxia. Seventeen young (average age 27 years) and 22 older (average age 57 years) healthy adult high altitude native Aymara men tested at 3600 m have average morning salivary testosterone concentrations of 282 and 241 pmol/l, respectively. The 31 urban men of both age groups have higher testosterone concentrations than the eight rural men and have mean haemoglobin concentrations significantly 0·7–1·0 g/dl higher within the normal high-altitude range, consistent with known effects of te...

Respiratory and hematological adaptations of young and older Aymara men native to 3600M

Abstract: This paper reports the results of a study designed to test the hypothesis that an inevitable concomitant of aging at high altitudes is chronic mountain sickness resulting from excess erythrocytosis secondary to exaggerated hypoxemia caused by aging processes in the respiratory system. It compares age differences in respiratory system function in oxygenating the blood measured as percent O2 saturation of arterial hemoglobin during wakefulness and sleep and in erythrocytosis measured as hemoglobin concentration in 17 young (22–35 years) and 16 older (47–68 years) rural and urban resident Bolivian Aymara men, healthy lifelong residents of 3,500–4,000 m who were tested at 3,600 m. The results do not support the hypothesis. Older urban men are significantly more hypoxemic during wakefulness and sleep than young urban men, while there are no age differences in the degree of hypoxemia among the rural residents. However, older urban men do not have the higher hemoglobin concentration predicted by the hypothesis. Both urban and rural older men have lower hemoglobin concentration than their young counterparts, a finding not attributable to age differences in nutritional status or testosterone concentration. Despite their relatively low hemoglobin concentration, older men have estimated arterial O2 content in the normal sea level range for young men and in this sense retain the capacity to adapt to high altitude at least through the seventh decade of life.