Metabolism: clinical and experimental
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Peptide YY (PYY) and ghrelin have been associated with the regulation of energy balance. The objectives of this study were to determine whether total ghrelin and PYY after a standardized meal predict appetite scores and ad libitum energy intake (EI) and to examine the relationship between total ghrelin and PYY and postprandial energy expenditure (PEE). Twenty-five premenopausal women (age, 50.4 +/- 2.0 years; body mass index, 23.5 +/- 2.2 kg/m(2)) were studied. ⋯ Appetite scores were consistently associated with ad libitum EI at lunch (r = -0.51 to 0.40, P < .05), whereas no association between EI and prelunch total ghrelin and PYY was observed. Finally, partial correlation analyses revealed that total PYY was a significant independent correlate of PEE at 60, 90, 120, and 150 minutes (r = 0.37-0.51, P = .05). These findings provide evidence that appetite scores are better correlates of EI than are circulating levels of total PYY or ghrelin and that total PYY could be involved in the regulation of PEE.
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Elevated cardiovascular mortality has been shown to be associated with increased arterial stiffness. However, the contribution of tissue accumulation of advanced glycation end products (AGEs) to increased arterial stiffness is unclear. We examined whether skin autofluorescence, a recently developed marker of tissue accumulation of AGEs, is associated with arterial stiffness in 120 Japanese patients with end-stage renal disease (ESRD) and 110 age- and sex-matched control subjects. ⋯ Multiple regression analyses showed that, in the group of all subjects, association of skin autofluorescence with PWV was significant even after adjustment for other covariates including the presence of ESRD and age. Moreover, for ESRD subjects, a significant association between skin autofluorescence and PWV was found, independent of age. Our findings demonstrate the potential usefulness of skin autofluorescence in people of color and demonstrate clinically for the first time the potential involvement of tissue accumulation of AGEs in the pathophysiology of arterial stiffness.
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Comparative Study
Oxidative stress in Cohen diabetic rat model by high-sucrose, low-copper diet: inducing pancreatic damage and diabetes.
Increased oxidative stress contributes to the development and progression of both types of diabetes mellitus (DM) and its complications. In the Cohen diabetic (CD) rats, a known genetic model of nutritionally induced type 2 DM, a high-sucrose, low-copper diet (HSD) induces within 4 weeks DM in the sensitive (CDs) rats but not in the resistant (CDr) rats. To assess the possible involvement of oxidative stress in the induction of DM, we studied the effect of HSD on the tissue levels of antioxidants and the extent of oxidative injuries in these animals in comparison with the regular outbred strain of nondiabetic Sabra rats. ⋯ Oxidative damage was evaluated by measuring lipid peroxidation and protein oxidation. (1) In all animals fed HSD, the levels of LMWAs were decreased in most organs, although not plasma. (2) A significant difference was consistently found in antioxidant enzymes' activities in the pancreas of HSD-fed CDs rats, but not in other tissues. (3) The activities of superoxide dismutase and catalase and the levels of malondialdehyde and protein carbonyl group increased, whereas the levels of LMWAs decreased, in the pancreas of HSD-fed CDs rats. In the CD rats that develop DM when fed HSD, the pancreas showed susceptibility to oxidative stress-induced injuries. Thus, enhanced oxidative stress seems to play a role in the pathogenesis of DM in this strain.
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An alcoholic extract of Artemisia dracunculus L (PMI 5011) has been shown to decrease glucose and improve insulin levels in animal models, suggesting an ability to enhance insulin sensitivity. We sought to assess the cellular mechanism by which this botanical affects carbohydrate metabolism in primary human skeletal muscle culture. We measured basal and insulin-stimulated glucose uptake, glycogen accumulation, phosphoinositide 3 (PI-3) kinase activity, and Akt phosphorylation in primary skeletal muscle culture from subjects with type 2 diabetes mellitus incubated with or without various concentrations of PMI 5011. ⋯ However, PMI 5011 significantly decreased levels of a specific protein tyrosine phosphatase, that is, PTP1B. Time course studies confirmed that protein abundance of PTP1B decreases in the presence of PMI 5011. The cellular mechanism of action to explain the effects by which an alcoholic extract of A dracunculus L improves carbohydrate metabolism on a clinical level may be secondary to enhancing insulin receptor signaling and modulating levels of a specific protein tyrosine phosphatase, that is, PTP1B.
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Peroxisome proliferator-activated receptor gamma coactivator-1alpha (PGC-1alpha) is considered to play a pivotal role in the exercise-induced metabolic adaptation of skeletal muscle. Although the oxidized form of nicotinamide adenine dinucloetide (NAD(+))-dependent histone deacetylase SIRT1 has been shown to mediate PGC-1alpha-induced metabolic adaptation, the effect of endurance exercise on the SIRT1 protein remains to be elucidated. The purposes of this study were (1) to investigate the distribution of SIRT1 and PGC-1alpha proteins in skeletal muscle and (2) to examine the effects of acute endurance exercise and low- or high-intensity exercise training on SIRT1 and PGC-1alpha protein expressions and on the metabolic components in rat skeletal muscle. ⋯ In the plantaris muscle, SIRT1, hexokinase activity, mitochondrial proteins and enzyme activities, and glucose transporter 4 were increased by high-intensity training whereas the PGC-1alpha was not. These results suggest that endurance exercise increases the skeletal muscle SIRT1 protein content. In addition, the findings also raise the possibility that the SIRT1 protein expression may play a potentially important role in such adaptations, whereas an increase in the PGC-1alpha protein expression is not necessary for such adaptations.