Possible resting metabolic rate modification by the circulating RBP4 in obese subjects.

AIM: Adipose tissue derived retinol-binding protein 4 (RBP-4), known as one of the most important adipokins, has a link with insulin resistance and metabolic syndrome in obesity. The purpose of this study was to investigate the possible correlation between fasting serum RBP4 and resting metabolic rate (RMR) as a predictor of weight gain, body composition and insulin resistance in obese and non-obese subjects. MATERIALS AND METHODS: In this case-control study, 73 obese and 90 non-obese participants were assessed following an overnight fasting for RMR by means of indirect calorimetry. Body composition was measured using body composition analyzer. Serum RBP4 levels were quantified by ELISA method. RESULTS: Circulating RBP4 level correlated positively with log insulin (r=0.278, p=0.04) in obese subjects. There were no significant correlation between RBP4 and body composition in obese subjects except fat free mass (r=0.42, p=0.001). We found reduced RMR/kg in higher RBP4 concentration, moreover, a negative correlation was found between RBP4 and RMR/kg (r=-0.35, p=0.01) in obese group. Based on ROC analysis and RMR/kg cut-off value (=20 kcal/24 h/kg) for predicting the risk of obesity, 83.3% of participants with RMR/kg<20 kcal/24 h/kg had high RBP4 concentration, however in subjects with RMR/kg≥20 kcal/24 h/kg this percentage was 16.7 (p=0.01). CONCLUSION: Our findings demonstrated that RBP4 concentration had relation with RMR which was different among obese and non-obese groups. These results may suggest the possible role of RBP4 in alteration of metabolic rate through insulin or other metabolic effects.

Impact of vitamin A supplementation on RAR gene expression in multiple sclerosis patients.

Vitamin A and its derivatives have been shown to modulate the immune system via retinoic acid receptor (RAR). This study explored the impact of retinyl palmitate supplementation on RAR subtype gene expression in peripheral blood mononuclear cells (PBMCs) in multiple sclerosis (MS) patients. The study designed as a double-blind randomized clinical trial in which relapsing remitting multiple sclerosis patients were evaluated. Both groups received one capsule 50,000 IU vitamin D3 per 2 weeks and one intramuscular injection interferon beta-1a per week. The intervention group received one 25,000 IU retinyl palmitate capsule daily for 6 months and the placebo group received one placebo capsule daily. The PBMCs were isolated from participants and the expression level changes of RAR-α and RAR-γ genes were determined by real-time PCR. After supplementation, in the intervention group, the RAR-α gene expression level was significantly decreased compared to the placebo group (p = 0.03); however, the expression of RAR-γ gene did not significantly change (p = 0.10). These results show that vitamin A supplementation can significantly downregulate the expression of RAR-α gene in PBMCs of MS patients that suggest the presence of in vivo regulatory mechanisms for the action of vitamin A on the immune system.

An exonic peroxisome proliferator-activated receptor-γ coactivator-1α variation may mediate the resting energy expenditure through a potential regulatory role on important gene expression in this pathway.

BACKGROUND/AIMS: We studied peroxisome proliferator-activated receptor-γ coactivator-1α (PPARGC1A) gene variations at the 23815227-23815706 positions and examined their possible correlation with obesity-related conditions and resting energy expenditure (REE). We investigated the expression of PPARGC1A, mitogen-activated protein kinase (MAPK) and uncoupling protein 2 (UCP2), which play key roles in cellular energy expenditure, in a cellular model consisting of peripheral blood mononuclear cells, and compared them with various genotypes of the PPARGC1A gene. METHODS: In total, 100 normal-weight and 129 obese subjects participated in the current study. All subjects were assessed for REE and body composition. We sequenced the PPARGC1A gene. Real-time PCR was used for determining the PPARGC1A, MAPK, and UCP2 gene expression. RESULTS: There were significant differences in terms of body mass index, fat mass, low-density lipoprotein, insulin levels, REE/kg body weight, and REE/lean body mass among rs17574213 genotypes. There were significant differences in total cholesterol and low-density lipoprotein cholesterol levels among the various genotypes of Gly482Ser (rs8192678) and rs3755863. The relative PPARGC1A, MAPK, and UCP2 gene expressions had similar trends in the two studied SNPs, and the expression level of these genes was lowest in the TT genotype of Gly482Ser and rs3755863 and highest in the CC genotype of Gly482Ser and rs3755863. CONCLUSIONS: Our findings suggest that PPARGC1A variations may influence PPARGC1A expression and the coordinating regulators of downstream targets in energy homeostasis. Further study is needed to shed some light on this process.

Effect of alpha-lipoic acid on blood glucose, insulin resistance and glutathione peroxidase of type 2 diabetic patients.

OBJECTIVE: To examine the effects of alpha-lipoic acid (ALA) treatment over a period of 2 months on fasting blood glucose (FBG), insulin resistance (IR), and glutathione peroxidase (GH-Px) activity in type 2 diabetes (T2DM) patients. METHODS: This study took place in Motahari Clinic, Shiraz, Iran, which is affiliated to Shiraz University of Medical Sciences from May to October 2006. Type 2 DM patients (n=57) were divided into 2 groups to receive either ALA (300 mg daily) or placebo by systematic randomization, and were followed-up for 8 weeks. After an overnight fasting and 2 hours after breakfast, patients' blood samples were drawn and tested for FBG, 2 hours PPG, serum insulin level, and GH-Px activity. RESULTS: The result of the study showed a significant decrease in FBG and PPG levels, IR-Homeostasis Model Assessment (IR-HOMA index) and GH-Px level in the ALA group. The comparison of differences between FBG and IR at the beginning and at the end of study in the ALA treated group and the placebo group were also significant. CONCLUSION: This study supports the use of ALA as an antioxidant in the care of diabetic patients.

Effect of vitamin C supplementation on postprandial oxidative stress and lipid profile in type 2 diabetic patients.

Diabetes mellitus is one of the most wide spread endocrine disorders and an important developing health problem in the world. Cardiovascular disease is a common complication of type 2 diabetes. Several risk factors for coronary heart disease cosegregate in type 2 diabetes, including hyperglycemia, hyperlipaemia, increases production of free radical and decrease in antioxidant defense system. In this study we evaluated the effect of vitamin C supplementation on fasting and postprandial oxidative stress and lipid profile in type 2 diabetic patients. 30 patients with type 2 diabetes from Nader Kazemi Clinic, Shiraz, Iran were randomly divided into 2 groups; vitamin C treatment group (1000 mg d(-1)) and placebo group from May to September 2010. Fasting and postprandial lipid profile and Malondialdehyde (MDA) level were measured at the beginning of the study and after six weeks of supplementation. Data analysis was carried out using Mann-Whitney U test with p < 0.05 being significant by SPSS software version 16.The result of the study showed a significantly decrease in fasting (p = 0.006) and postprandial MDA (p < 0.001) in vitamin C group compare to placebo group but not in lipid profile. This study suggests that vitamin C supplementation can decrease fasting and postprandial oxidative stress and may prevent diabetes complication.