Metabolism: clinical and experimental
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Randomized Controlled Trial Clinical Trial
Effects of phytosterol ester-enriched margarine on plasma lipoproteins in mild to moderate hypercholesterolemia are related to basal cholesterol and fat intake.
Dietary phytosterols have been reported to lower total and low-density lipoprotein (LDL) cholesterol. However, less is known about the influence of cholesterol and fat intake on the cholesterol-lowering effect of esterified phytosterols in mild to moderate hypercholesterolemia. Sixty-three healthy subjects (38 women, 25 men, 42 +/- 11 years, LDL cholesterol > 130 mg/dL) were investigated in a randomized, double-blind, placebo-controlled, cross-over study. ⋯ In the tertiles with the highest dietary intake of cholesterol, energy, total fat, and saturated fatty acids, and with the highest baseline proportion of campesterol to cholesterol, LDL cholesterol reduction was 11.6% (P <.001), 9.5% (P =.001), 9.4% (P =.001), 8.4% (P =.005), and 6.2% (P =.014), respectively. Triglycerides, plasma viscosity, and fibrinogen concentration did not change significantly. The improvements of LDL, HDL, total cholesterol, apolipoprotein B concentrations, and LDL/HDL cholesterol ratio during the daily consumption of a phytosterol ester-enriched margarine were most marked in those subjects with a high dietary intake of cholesterol, energy, total fat, and saturated fatty acids and with high baseline cholesterol absorption.
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The aim of this article was to review the evidence for a metabolically normal subset of the obese and its implications for clinical and research work. The methods included literature review and correspondence with authors. Since 1947, when Vague described a relation between distribution of body fat and the risk factors for cardiovascular disease, much evidence has suggested that early onset of the obesity, hyperplasia of normal adipocytes, and normal quantities of visceral abdominal fat may be associated with a favorable metabolic response in obese subjects. ⋯ The criteria for selection of obese research subjects may favor inclusion of an OBMN subset, which may invalidate statistical analysis. Findings suggesting the OBMN subset include family members with uncomplicated obesity, early onset of the obesity, fasting plasma insulin within normal range, and normal distribution of the excess fat. Hormonal, genetic studies, and prospective studies will help to clarify the significance and underlying mechanisms of this subset.
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Physical exercise is frequently recommended for the treatment of type 2 diabetes, whether as primary therapy with diet modification or as an adjunct to drug therapy. We hypothesized that mild exercise would enhance the glucose-lowering effects of 2 oral antihyperglycemic drugs, metformin and acarbose, in an animal model of type 2 diabetes. Eight-week-old male C57BL/Ks (db/db) mice were sorted into control and exercise groups and dosed daily for 4 weeks with vehicle, metformin (150 mg/kg/d), or acarbose (40 mg/kg/d). ⋯ In conclusion, exercise and drug therapy independently decreased serum glucose in db/db mice, and these effects did not appear to be synergistic. In addition, exercise training maintained serum insulin concentrations and increased tissue glycogen storage. These results suggest that exercise has the potential to add to the efficacy of oral antihyperglycemic drugs.
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Obesity is related to the risk for developing non-insulin-dependent diabetes mellitus (NIDDM), hypertension, and cardiovascular disease. Visceral adipose tissue (VAT) has been proposed to mediate these relationships. Abdominal subcutaneous adipose tissue (SAT) is divided into 2 layers by a fascia, the fascia superficialis. ⋯ In both men and women, the addition of VAT and subcutaneous abdominal adipose tissue depots only slightly increased the R(2). In men, when body fat compartments were considered independently, DSAT explained a greater portion of the variance (R(2) =.528) in fasting insulin than VAT (R(2) =.374) or non-VAT, non-DSAT subcutaneous adipose tissue (R(2) =.375). These data suggest that total body fat is a major contributor to the metabolic sequelae of obesity, with specific fat depots, VAT, and DSAT also making significant contributions.
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To investigate the effect of oral nicotine administration on insulin resistance and insulin secretion in an animal model of obesity, Zucker fatty rats were administered nicotine tartrate dihydrate orally through tap water (4.6 mg/kg/d, N group). Plasma nicotine concentrations in N group were 33.67 +/- 10.49 ng/mL. The control (C) group consisted of pair-fed control rats. ⋯ The TNF-alpha levels in visceral fat tissues in N group were significantly lower than those in C group. These results suggest that oral nicotine administration reduces insulin resistance in obese diabetic rats by decreasing production of TNF-alpha in the visceral fat tissues. Decreased islet size may be a secondary phenomenon induced by ameliorated insulin resistance, because the cellularity and fibroelastic tissues were not affected by the nicotine.