14 research outputs found
Use of a food frequency questionnaire in American Indian and Caucasian pregnant women: a validation study
BACKGROUND: Food frequency questionnaires (FFQs) have been validated in pregnant women, but few studies have focused specifically on low-income women and minorities. The purpose of this study was to examine the validity of the Harvard Service FFQ (HSFFQ) among low-income American Indian and Caucasian pregnant women. METHODS: The 100-item HSFFQ was administered three times to a sample of pregnant women, and two sets of 24-hour recalls (six total) were collected at approximately 12 and 28 weeks of gestation. The sample included a total of 283 pregnant women who completed Phase 1 of the study and 246 women who completed Phase 2 of the study. Deattenuated Pearson correlation coefficients were used to compare intakes of 24 nutrients estimated from the second and third FFQ to average intakes estimated from the week-12 and week-28 sets of diet recalls. RESULTS: Deattenuated correlations ranged from 0.09 (polyunsaturated fat) to 0.67 (calcium) for Phase 1 and from 0.27 (sucrose) to 0.63 (total fat) for Phase 2. Average deattenuated correlations for the two phases were 0.48 and 0.47, similar to those reported among other groups of pregnant women. CONCLUSION: The HSFFQ is a simple self-administered questionnaire that is useful in classifying low-income American Indian and Caucasian women according to relative dietary intake during pregnancy. Its use as a research tool in this population may provide important information about associations of nutrient intakes with pregnancy outcomes and may help to identify groups of women who would benefit most from nutritional interventions
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Marked and rapid decreases of circulating leptin in streptozotocin diabetic rats: reversal by insulin.
Evidence for regulation of circulating leptin by insulin is conflicting. Diabetes was induced in rats with streptozotocin (STZ; 40 mg.kg(-1).day(-1) x 2 days) to examine the effect of insulin-deficient diabetes and insulin treatment on circulating leptin. After 12 wk, plasma leptin concentrations in untreated rats were all < 0.4 ng/ml versus 4.9 +/- 0.9 ng/ml in control animals (P < 0.005). In rats treated with subcutaneous insulin implants for 12 wk, which reduced hyperglycemia by approximately 50%, plasma leptin was 2.1 +/- 0.6 ng/ml, whereas leptin concentrations were 6.0 +/- 1.6 ng/ml in insulin-implanted rats receiving supplemental injections of insulin for 4 days to normalize plasma glucose (P < 0.005 vs. STZ untreated). In a second experiment, plasma leptin was monitored at biweekly intervals during 12 wk of diabetes. In rats treated with insulin implants, plasma leptin concentrations were inversely proportional to glycemia (r = -0.64; P < 0.0001) and unrelated to body weight (P = 0.40). In a third experiment, plasma leptin concentrations were examined very early after the induction of diabetes. Within 24 h after STZ injection, plasma insulin decreased from 480 +/- 30 to 130 +/- 10 pM (P < 0.0001), plasma glucose increased from 7.0 +/- 0.2 to 24.8 +/- 0.5 mM, and plasma leptin decreased from 3.2 +/- 0.2 to 1.2 +/- 0.1 ng/ml (delta = -63 +/- 3%, P < 0.0001). In a subset of diabetic rats treated with insulin for 2 days, glucose decreased to 11.7 +/- 3.9 mM and leptin increased from 0.5 +/- 0.1 to 2.9 +/- 0.6 ng/ml (P < 0.01) without an effect on epididymal fat weight. The change of leptin was correlated with the degree of glucose lowering (r = 0.75, P < 0.05). Thus insulin-deficient diabetes produces rapid and sustained decreases of leptin that are not solely dependent on weight loss, whereas insulin treatment reverses the hypoleptinemia. We hypothesize that decreased glucose transport into adipose tissue may contribute to decreased leptin production in insulin-deficient diabetes
Increased Renal Tubular Reabsorption of Calcium and Magnesium by the Offspring of Diabetic Rat Pregnancy
Diabetic pregnancy has a marked influence on offspring calcium and magnesium homeostasis. Urinary excretion of calcium and magnesium is reduced, yet offspring of diabetic pregnancy exhibit hypomagnesemia and hypocalcemia. The aim of this study was to measure renal hemodynamic and tubular function in the offspring of diabetic (OD) and control, nondiabetic (OC) rats at 4 and 8 wk of age to determine the glomerular and tubular mechanisms through which renal calcium and magnesium handling are programmed in utero. The fraction of filtered calcium that was excreted was significantly lower in OD at both 4 and 8 wk of age [8 wk: OC (n = 6), 11.8 ± 2.9 versus OD (n = 5), 4.3 ± 0.6%; p < 0.05] and that of magnesium was lower at 8 wk of age [OC (n = 6), 42.4 ± 7.5 versus OD (n = 5), 13.0 ± 1.7%; p < 0.01]. This increased reabsorption occurred despite an elevated GFR in OD. These findings clearly indicate that tubular reabsorptive mechanisms for calcium and magnesium are increased markedly in OD. Serum PTH concentration was reduced in 8-wk-old OD [OC (n = 7), 539.4 ± 142.1 versus OD (n = 9), 174.3 ± 69.4 pg/ml; p < 0.05], consistent with previous reports in human infants. Taken together, these observations suggest that the basis for the altered renal magnesium and calcium handling in OD involves increased tubular transport activity and possibly increased sensitivity of these mechanisms to PTH