Vitamin B(12) and folate concentrations during pregnancy and insulin resistance in the offspring: the Pune Maternal Nutrition Study

Aims/hypotheses: raised maternal plasma total homocysteine (tHcy) concentrations predict small size at birth, which is a risk factor for type 2 diabetes mellitus. We studied the association between maternal vitamin B(12), folate and tHcy status during pregnancy, and offspring adiposity and insulin resistance at 6 years. Methods: in the Pune Maternal Nutrition Study we studied 700 consecutive eligible pregnant women in six villages. We measured maternal nutritional intake and circulating concentrations of folate, vitamin B(12), tHcy and methylmalonic acid (MMA) at 18 and 28 weeks of gestation. These were correlated with offspring anthropometry, body composition (dual-energy X-ray absorptiometry scan) and insulin resistance (homeostatic model assessment of insulin resistance [HOMA-R]) at 6 years. Results: two-thirds of mothers had low vitamin B(12) (10 mumol/l); only one had a low erythrocyte folate concentration. Although short and thin (BMI), the 6-year-old children were relatively adipose compared with the UK standards (skinfold thicknesses). Higher maternal erythrocyte folate concentrations at 28 weeks predicted higher offspring adiposity and higher HOMA-R (both p < 0.01). Low maternal vitamin B(12) (18 weeks; p = 0.03) predicted higher HOMA-R in the children. The offspring of mothers with a combination of high folate and low vitamin B(12) concentrations were the most insulin resistant. Conclusions/interpretations: low maternal vitamin B(12) and high folate status may contribute to the epidemic of adiposity and type 2 diabetes in India

Oxygen consumption and blood flow distribution in perfused skeletal muscle of chinook salmon

An isolated, perfused salmon tail preparation showed oxyconformance at low oxygen delivery rates. Addition of pig red blood cells to the perfusing solution at a haematocrit of 5 or 10% allowed the tail tissues to oxyregulate. Below ca. 60 ml O2 kg&minus;1 h&minus;1 of oxygen delivery (DO2), VO2 was delivery dependent. Above this value additional oxygen delivery did not increase VO2 of resting muscle above ca. 35 ml O2 kg&minus;1 h&minus;1. Following electrical stimulation, VO2 increased to ca. 65 ml O2 kg&minus;1 h&minus;1, with a critical DO2 of ca. 150 ml O2 kg&minus;1 h&minus;1. Dorsal aortic pressure fell to 69% of the pre-stimulation value after 5 min of stimulation and to 54% after 10 min. Microspheres were used to determine blood flow distribution (BFD) to red (RM) and white muscle (WM) within the perfused myotome. Mass specific BFD ratio at rest was found to be 4.03 &plusmn; 0.49 (RM:WM). After 5 min of electrical stimulation the ratio did not change. Perfusion with saline containing the tetrazolium salt 3-(4,5-Dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) revealed significantly more mitochondrial activity in RM. Formazan production from MTT was directly proportional to time of perfusion in both red and WM. The mitochondrial activity ratio (RM:WM) did not change over 90 min of perfusion.<br /