Peroxisome proliferator-activated receptor-␥ coactivator (PGC)-1␣ has been shown to play critical roles in regulating mitochondria biogenesis, respiration, and muscle oxidative phenotype. Furthermore, reductions in the expression of PGC-1␣ in muscle have been implicated in the pathogenesis of type 2 diabetes. To determine the effect of increased muscle-specific PGC-1␣ expression on muscle mitochondrial function and glucose and lipid metabolism in vivo, we examined body composition, energy balance, and liver and muscle insulin sensitivity by hyperinsulinemic-euglycemic clamp studies and muscle energetics by using 31 P magnetic resonance spectroscopy in transgenic mice. Increased expression of PGC-1␣ in muscle resulted in a 2.4-fold increase in mitochondrial density, which was associated with an Ϸ60% increase in the unidirectional rate of ATP synthesis. Surprisingly, there was no effect of increased muscle PGC-1␣ expression on whole-body energy expenditure, and PGC-1␣ transgenic mice were more prone to fat-induced insulin resistance because of decreased insulin-stimulated muscle glucose uptake. The reduced insulin-stimulated muscle glucose uptake could most likely be attributed to a relative increase in fatty acid delivery/triglyceride reesterfication, as reflected by increased expression of CD36, acyl-CoA:diacylglycerol acyltransferase1, and mitochondrial acyl-CoA:glycerol-sn-3-phosphate acyltransferase, that may have exceeded mitochondrial fatty acid oxidation, resulting in increased intracellular lipid accumulation and an increase in the membrane to cytosol diacylglycerol content. This, in turn, caused activation of PKC , decreased insulin signaling at the level of insulin receptor substrate-1 (IRS-1) tyrosine phosphorylation, and skeletal muscle insulin resistance.diacylglycerol ͉ fatty acid oxidation ͉ insulin resistance ͉ magnetic resonance spectroscopy ͉ mitochondria

Acetyl-CoA carboxylase 2 (ACC)2 is a key regulator of mitochondrial fat oxidation. To examine the impact of ACC2 deletion on whole-body energy metabolism, we measured changes in substrate oxidation and total energy expenditure in Acc2 ؊/؊ and WT control mice fed either regular or high-fat diets. To determine insulin action in vivo, we also measured whole-body insulinstimulated liver and muscle glucose metabolism during a hyperinsulinemic-euglycemic clamp in Acc2 ؊/؊ and WT control mice fed a high-fat diet. Contrary to previous studies that have suggested that increased fat oxidation might result in lower glucose oxidation, both fat and carbohydrate oxidation were simultaneously increased in Acc2 ؊/؊ mice. This increase in both fat and carbohydrate oxidation resulted in an increase in total energy expenditure, reductions in fat and lean body mass and prevention from diet-induced obesity. Furthermore, Acc2 ؊/؊ mice were protected from fat-induced peripheral and hepatic insulin resistance. These improvements in insulin-stimulated glucose metabolism were associated with reduced diacylglycerol content in muscle and liver, decreased PKC activity in muscle and PKC activity in liver, and increased insulin-stimulated Akt2 activity in these tissues. Taken together with previous work demonstrating that Acc2 ؊/؊ mice have a normal lifespan, these data suggest that Acc2 inhibition is a viable therapeutic option for the treatment of obesity and type 2 diabetes. diet-induced obesity prevention ͉ intracellular diacylglycerol ͉ increased fat oxidation ͉ insulin resistance prevention

BackgroundThe association between sarcopenia and cardiovascular disease (CVD) in elderly people has not been adequately assessed. The aim of this study was to investigate whether CVD is more prevalent in subjects with sarcopenia independent of other well-established cardiovascular risk factors in older Korean adults.MethodThis study utilized the representative Korean population data from the Korea National Health and Nutrition Examination Survey (KNHANES) which was conducted in 2009. Subjects older than 65 years of age with appendicular skeletal muscle mass (ASM) determined by dual energy X-ray absorptiometry were selected. The prevalence of sarcopenia in the older Korean adults was investigated, and it was determined whether sarcopenia is associated with CVD independent of other well-known risk factors.Results1,578 subjects aged 65 years and older with the data for ASM were selected, and the overall prevalence of sarcopenia was 30.3% in men and 29.3% in women. Most of the risk factors for CVD such as age, waist circumference, body mass index, fasting plasma glucose and total cholesterol showed significant negative correlations with the ratio between appendicular skeletal muscle mass and body weight. Multiple logistic regression analysis demonstrated that sarcopenia was associated with CVD independent of other well-documented risk factors, renal function and medications (OR, 1.768; 95% CI, 1.075–2.909, P = 0.025).ConclusionsSarcopenia was associated with the presence of CVD independent of other cardiovascular risk factors after adjusting renal function and medications.

Background A proportion of obese subjects appear metabolically healthy (MHO) but little is known about the natural history of MHO and factors predicting its future conversion to metabolically unhealthy obese (MUO). Objectives The aim was to determine prospectively the frequency of conversion of MHO to MUO and the clinical variables that independently predicted this conversion, with a particular focus on the role of body composition. Methods We identified 85 Japanese Americans with MHO (56 men, 29 women), aged 34–73 years (mean age 49.8 years) who were followed at 2.5, 5, and 10 years after enrollment with measurements of metabolic characteristics, lifestyle, and abdominal and thigh fat areas measured by computed tomography. Obesity was defined using the Asian body mass index criterion of ≥ 25 kg/m2. Metabolically healthy was defined as the presence of ≤ 2 of 5 metabolic syndrome components proposed by the National Cholesterol Education Program Adult Treatment Panel III, while metabolically unhealthy was defined as ≥ 3 components. Results Over 10 years of follow-up, 55 MHO individuals (64.7%) converted to MUO. Statistically significant univariate predictors of conversion included dyslipidemia, greater insulin resistance, and greater visceral abdominal (VAT) and subcutaneous abdominal fat area (SAT). In multivariate analysis, VAT (odds ratio per 1 SD increment (95% confidence interval) 2.04 (1.11 – 3.72), P=0.021), high density lipoprotein (HDL) cholesterol (0.24 (0.11 – 0.53), P<0.001), fasting plasma insulin (2.45 (1.07 – 5.62), P=0.034), and female sex (5.37 (1.14 – 25.27), P=0.033) were significantly associated with future conversion to MUO. However, SAT was not an independent predictor for future conversion to MUO. Conclusions In this population, MHO was a transient state, with nearly two-thirds developing MUO over 10 years, with higher conversion to MUO independently associated with VAT, female sex, higher fasting insulin level, and lower baseline HDL cholesterol level.

L-ascorbic acid (vitamin C) is one of the well-known anti-viral agents, especially to influenza virus. Since the in vivo anti-viral effect is still controversial, we investigated whether vitamin C could regulate influenza virus infection in vivo by using Gulo (-/-) mice, which cannot synthesize vitamin C like humans. First, we found that vitamin C-insufficient Gulo (-/-) mice expired within 1 week after intranasal inoculation of influenza virus (H3N2/Hongkong). Viral titers in the lung of vitamin C-insufficient Gulo (-/-) mice were definitely increased but production of anti-viral cytokine, interferon (IFN)-α/β, was decreased. On the contrary, the infiltration of inflammatory cells into the lung and production of pro-inflammatory cytokines, tumor necrosis factor (TNF)-α and interleukin (IL)-α/β, were increased in the lung. Taken together, vitamin C shows in vivo anti-viral immune responses at the early time of infection, especially against influenza virus, through increased production of IFN-α/β.

Research within the anatomical sciences often relies on human cadaveric tissues. Without the good will of these donors who allow us to use their bodies to push

Elevated levels of both carboxylated and uncarboxylated forms of osteocalcin were associated with improved glucose tolerance. Moreover, the uncarboxylated form of osteocalcin was found to be associated with enhanced beta-cell function, and the carboxylated form was associated with improved insulin sensitivity in middle-aged male subjects.

Insulin resistance is a major factor in the pathogenesis of type 2 diabetes and is strongly associated with obesity. Increased concentrations of intracellular fatty acid metabolites have been postulated to interfere with insulin signaling by activation of a serine kinase cascade involving PKCθ in skeletal muscle. Uncoupling protein 3 (UCP3) has been postulated to dissipate the mitochondrial proton gradient and cause metabolic inefficiency. We therefore hypothesized that overexpression of UCP3 in skeletal muscle might protect against fat-induced insulin resistance in muscle by conversion of intramyocellular fat into thermal energy. Wild-type mice fed a high-fat diet were markedly insulin resistant, a result of defects in insulin-stimulated glucose uptake in skeletal muscle and hepatic insulin resistance. Insulin resistance in these tissues was associated with reduced insulin-stimulated insulin receptor substrate 1-(IRS-1-) and IRS-2-associated PI3K activity in muscle and liver, respectively. In contrast, UCP3-overexpressing mice were completely protected against fat-induced defects in insulin signaling and action in these tissues. Furthermore, these changes were associated with a lower membrane-to-cytosolic ratio of diacylglycerol and reduced PKCθ activity in whole-body fat-matched UCP3 transgenic mice. These results suggest that increasing mitochondrial uncoupling in skeletal muscle may be an excellent therapeutic target for type 2 diabetes mellitus.