The Tibetan population, long a resident on the Qinghai-Tibetan Plateau, has lower hemoglobin concentrations than Han Chinese migrants, but it is incompletely known how gender affects the hemoglobin concentrations in the two populations at various altitudes. Measurements of hemoglobin concentration were obtained in 5,887 healthy male and female Tibetan and Han residents aged 5-60 yr, at altitudes of 2,664, 3,813, 4,525, and 5,200 m. Multiple regression equations showed the beta-coefficients for altitude and for age were higher (P < 0.05) in Han men than in Tibetan men and in Han women than in Tibetan women. Analysis indicated a significant three-way interaction between altitude, gender, and ethnicity (chi2 = 3.72, P = 0.05). With increasing altitude, men progressively had more hemoglobin than women in the Han, but not the Tibetan, population. Above 2,664 m, this gender-related difference in hemoglobin concentration increased from childhood to young adulthood more in Han than in Tibetans. We suggest that the Han-Tibetan ethnic difference in the effect of altitude on hemoglobin concentration depends to a large extent on gender.
1. Male Sprague-Dawley rats were fed on either a purified, fibre-free diet or a diet in which half the maize starch was replaced with uncooked amylomaize or potato starch (equivalent to 100 or 200 g amylase-resistant starch (ARS)/kg diet respectively). Changes in short-chain fatty acids (SCFA), pH, ammonia and a number of bacterial variables in caecal contents were then assessed.2. Both ARS supplements decreased caecal content pH by approximately 1–2 units, with an associated reduction in ammonia concentration. Potato starch significantly decreased the concentration of SCFA in the hind-gut, while amylomaize supplementation increased propionic and butyric acids but decreased the occurrence of minor, branched-chain fatty acids.3. Caecal bacterial biotransformation activities (β-glucosidase (EC3.2.1.21), β-glucuronidase (EC3.2.1.31), reduction ofp-nitrobenzoic acid, apparent ammonia formation) were consistently decreased by both ARS sources.4. The results demonstrate that amylase-resistant carbohydrate altered toxicologically important functions in the large-intestinal flora of the rat.
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