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Muscle inactivity leads to muscle atrophy and insulin resistance. The branched-chain amino acid (BCAA) leucine interacts with the insulin signaling pathway to modulate glucose metabolism. We have tested the ability of a high-protein BCAA-enriched diet to prevent insulin resistance during long-term bed rest (BR). Stable isotopes were infused to determine glucose and protein kinetics in the postabsorptive state and during a hyperinsulinemic-euglycemic clamp in combination with amino acid infusion (Clamp + AA) before and at the end of 60 days of BR in two groups of healthy, young women receiving eucaloric diets containing 1 g of protein/kg per day (n = 8) or 1.45 g of protein/kg per day enriched with 0.15 g/kg per day of BCAAs (leucine/valine/isoleucine = 2/1/1) (n = 8). Body composition was determined by Dual X-ray Absorptiometry. BR decreased lean body mass by 7.6 ± 0.3 % and 7.2 ± 0.8 % in the groups receiving conventional or high protein-BCAA diets, respectively. Fat mass was unchanged in both groups. At the end of BR, percent changes of insulin-mediated glucose uptake significantly (p = 0.01) decreased in the conventional diet group from 155 ± 23 % to 84 ± 10 % while did not change significantly in the high protein-BCAA diet group from 126 ± 20 % to 141 ± 27 % (BR effect, p = 0.32; BR/diet interaction, p = 0.01; Repeated Measures ANCOVA). In contrast, there were no BR/diet interactions on proteolysis and protein synthesis Clamp + AA changes in the conventional diet and the high protein-BCAA diet groups. A high protein-BCAA enriched diet prevented inactivity-induced insulin resistance in healthy women. [ABSTRACT FROM AUTHOR]

Obesity is characterized by fat mass excess (FM), extra cellular water increase (ECW) and, with ageing, decrease in fat free mass (FFM). The validity of body impedance analysis (BIA) in patients with mild to severe obesity is still debated. The purpose of this study is to describe the Resistance (Rz) and Reactance (Xc) values obtained by Body Impedance Analysis (BIA) in a wide cohort of Italian patients with mild to severe obesity. The secondary endpoint is to describe the resulting body composition values (as percentage and indexes) in this population. The study enrolled adult in-patients with mild to severe obesity (classified with class I, II and III obesity) undergoing clinical care rehabilitation program for obesity complications and weight loss. BIA values were grouped by sex, BMI and age classes. A total of 8303 patients with obesity, aged 18 to 90 y, were studied. The Resistance (Rz) and Reactance (Xc) were reported by sex, age and BMI classes. In women and men both, the phase angle (PhA) decreases with increasing BMI (kg/m2) and the resulting BIA vector was significantly shifted. The FM index (FMI) was higher (p < 0.0001) in women while FFM index (FFMI) was higher in men (p < 0.0001) and significantly associated with BMI. FFMI decreased with age in both sex (p < 0.0001). Skeletal mass (SM) presents a progressive reduction in relation to age and gender both. The present BIA-based body composition analysis in a wide cohort of mild to severe obese patients revealed a significantly decreased Rz and Xc values with a consequent significant decrease of PhA in a BMI-dependent manner. The body compartments estimation with available equations was BMI, sex and age dependent. These observational results could be the basis for the development of new equations adapted for patients suffering from obesity. [Display omitted] • BIA in patients with severe obesity is debated. • PhA decreases with increasing BMI. • BIA ranges in severe obesity were shown. [ABSTRACT FROM AUTHOR]

Waist circumference (WC) is the currently recommended marker of central fat for cardiometabolic risk screening. Alternative surrogate markers have been recently proposed to better reflect the metabolic impact of central fat accumulation per se, based on WC normalization by height (Weight-to-Height Ratio – WtoH; Body Roundness Index – BRI) or body mass index (BMI) without (A Body Shape Index – ABSI) or with inclusion of plasma triglyceride and HDL-cholesterol concentrations (Visceral Adiposity Index – VAI). We investigated associations between WtoH, BRI, ABSI or VAI and insulin resistance (HOMA-index) or metabolic syndrome (MetS) in a general population cohort from the North-East Italy Mo.Ma. study (n = 1965, age = 49 ± 13 years, BMI = 26.7 ± 5.2 kg/m2). Baseline values were also evaluated as predictors of future insulin resistance and MetS in overweight-obese individuals undergoing 5-year follow-up (Ow-Ob) (n = 263; age = 54 ± 9, BMI = 30,7 ± 4,1). Compared to WC or BMI, basal WtoH and BRI were similarly associated with baseline HOMA and MetS prevalence after multiple adjustments (P < 0.001) and all markers similarly predicted 5-year HOMA and MetS (P < 0.001). Under basal conditions, superimposable results were observed for VAI whereas ABSI was less accurate or unable to identify baseline HOMA and MetS (p < 0.05 vs WtoH-BRI-VAI-WC-BMI). VAI had highest 5-year risk predictive value in Ow-Ob [ROC Area Under the Curve (AUC) VAI > WtoH-BRI-WC-BMI; p < 0.05] while no predictive value was in contrast observed for ABSI (ROC AUC ABSI < WtoH-BRI-WC-BMI; p < 0.05). Using alternate formulae with plasma lipid inclusion in ABSI and removal from VAI calculations completely reversed their 5-year predictive value and AUC. The current findings do not support replacement of WC with height-normalized anthropometric central fat surrogate markers to predict cardiometabolic risk in the general and overweight-obese population. BMI-normalization impairs risk assessment unless plasma lipid concentrations are available and included in calculations. [ABSTRACT FROM AUTHOR]

Summary Background & aims Physical inactivity is associated with lean body mass wasting, oxidative stress and pro-inflammatory changes of cell membrane lipids. Alkalinization may potentially counteract these alterations. We evaluated the effects of potassium bicarbonate supplementation on protein kinetics, glutathione status and pro- and anti-inflammatory polyunsaturated fatty acids (PUFA) in erythrocyte membranes in humans, during experimental bed rest. Methods Healthy, young, male volunteers were investigated at the end of two 21-day bed rest periods, one with, and the other without, daily potassium bicarbonate supplementation (90 mmol × d−1), according to a cross-over design. Oxidative stress in erythrocytes was evaluated by determining the ratio between reduced (GSH) and oxidized glutathione (GSSG). Glutathione turnover and phenylalanine kinetics, a marker of whole body protein metabolism, were determined by stable isotope infusions. Erythrocyte membranes PUFA composition was analyzed by gas-chromatography. Results At the end of the two study periods, urinary pH was 10 ± 3% greater in subjects receiving potassium bicarbonate supplementation (7.23 ± 0.15 vs. 6.68 ± 0.11, p < 0.001). Alkalinization increased total glutathione concentrations by 5 ± 2% (p < 0.05) and decreased its rate of clearance by 38 ± 13% (p < 0.05), without significantly changing GSH-to-GSSG ratio. After alkalinization, net protein balance in the postabsorptive state improved significantly by 17 ± 5% (p < 0.05) as well as the sum of n-3 PUFA and the n-3-to-n-6 PUFA ratio in erythrocyte membranes (p < 0.05). Conclusions Alkalinization during long-term inactivity is associated with improved glutathione status, anti-inflammatory lipid pattern in cell membranes and reduction in protein catabolism at whole body level. This study suggests that, in clinical conditions characterized by inactivity, oxidative stress and inflammation, alkalinization could be a useful adjuvant therapeutic strategy. [ABSTRACT FROM AUTHOR]

Background & aims: Sarcopenic obesity may be defined by a high fat to fat-free mass (FM/FFM) ratio. Skeletal muscle may be negatively influenced by th e pro-inflammatory milieu associated with visceral fat, while the loading effect induced by a heavier body mass index (BMi) may enhance muscle anabolism. Recently, a new anthropometric measure based on waist circumference (A Body Shape Index, ABSI) was developed. In this study we have assessed the predictive power of ABSI on the FFM index (FFMI), a surrogate marker of lean mass. Methods: Standard anthropometric parameters and ABSI as well as body composition data (fat and fat-free mass determined by bioelectrical impedance analysis) were assessed in 111 female and 89 male overweight/obese subjects, with no clinically significant co-morbidities. Groups with higher- or lower-ABSI were identified according to median values of this index. Results: In women and men, ABSI did not correlate with BMI, while multiple linear regression indicated that BMI ((β-coefficients: 0.62 and 0.77, respectively) and ABSI (β-coefficients: -0.26 and -0.22, respectively) independently predicted FFMI (multiple R: 0.72 and 0.83, respectively, P < 0.001). Men and women with lower-ABSI exhibited significantly greater FFMI than the higher-ABSI groups for comparable values of BMI. In men, ABSI was correlated positively with C-reactive protein (CRP) (R = 0.30; P < 0.05) and negatively with th e reciprocal of insulin (R = 0.28; P < 0.05), an index of insulin sensitivity. FM/FFM ratio significantly (P < 0.01) correlated with CRP (R = 0.31) in women only. Conclusions: ABSI, a recently introduced marker of abdominal adiposity, may contribute to define the risk of sarcopenia in overweight/obese individuals. [ABSTRACT FROM AUTHOR]

Summary: Background & aims: We performed a cross-sectional study on adult HIV-infected patients, on HAART, without calcium or vitamin D supplementation to evaluate if the cardiovascular risk or the presence of osteoporosis may be predictive factors of an optimal daily calcium intake (DCI>1000 mg/day). Methods: Patients underwent a dual-energy X-ray absorptiometry, measured biochemical parameters and compiled a validated questionnaire for the assessment of DCI. Osteoporosis (OP) was defined according to the WHO classification at either the vertebral spine or femoral neck. Cardiovascular risk was assessed by the 10-year Framingham cardiovascular risk score. Results: 200 HIV-infected patients evaluated: 171 (86%) males with a median age of 48.1 (42.3–53.8) years and 10.6 (4.3–13.6) years of HAART exposure. DCI was 889 (589–1308) mg/day and 79 (40%) patients had an optimal DCI. Framingham risk>20% was found in 13 (6.7%) patients and femoral OP was diagnosed in 12 (6%) pts. By multivariate analysis, optimal DCI was more likely in patients with a Framingham risk>20% [OR = 5.547, 95% CI:1.337, p = 0.025] and less likely in patients with femoral osteoporosis [OR = 0.159, 95% CI: 0.018–0.790, p = 0.047]. Conclusions: We found that an optimal dietary calcium intake was more likely in patients with high cardiovascular risk and no femoral osteoporosis. [Copyright &y& Elsevier]

Summary: Background & aims: Involvement of insulin in diabetes-associated liver triglyceride deposition and its potential pathways remain incompletely defined. SIRT1 may negatively modulate lipogenesis and liver triglyceride accumulation, involving AMP-activated protein kinase (AMPK) activation. In streptozotocin-diabetic rats, we hypothesized that insulin negatively modulates liver SIRT1 and activates AMPK-inhibited lipogenic mediators leading to triglyceride accumulation. The impact of insulin deprivation (INS−) and replacement (INS+) on liver inflammation and mitochondrial oxidative capacity (also potentially regulating triglyceride deposition) was also measured. Methods: Streptozotocin-diabetic rats under chronic (8-week) INS− and INS+. Results: Compared to INS− (P < 0.05), INS+ had low liver SIRT1 with low AMPK activating phosphorylation, low inactivating phosphorylation of its lipogenic target acetyl-CoA carboxylase and high tissue triglycerides. INS− (P < 0.05 vs Control) had liver inflammation and high mitochondrial oxidative capacity, but neither was modulated by INS+. Pair-feeding showed no influence of spontaneous overeating on insulin-induced changes. Conclusions: Insulin replacement downregulates SIRT1 and AMPK activation in vivo in streptozotocin-diabetic rat liver, likely contributing to insulin-induced liver triglyceride accumulation. Under the current experimental conditions, insulin-deprived diabetes is associated with liver inflammation and high mitochondrial oxidative capacity, that are not affected by insulin replacement and are therefore unlikely to contribute to tissue triglyceride changes in this model. [Copyright &y& Elsevier]