Xiufa Sun

Oxidative stress, antioxidant status and DNA damage in patients with impaired glucose regulation and newly diagnosed Type 2 diabetes

Previous studies have postulated the association between oxidative stress and Type 2 diabetes. Considering the long pre-diabetic period with IGR (impaired glucose regulation) and its high risk of developing diabetes, to test this hypothesis, we have investigated oxidative stress pathways and DNA damage in patients with IGR and newly diagnosed Type 2 diabetes. The study population consisted of 92 subjects with NGT (normal glucose tolerance), 78 patients with IGR and 113 patients with newly diagnosed diabetes. Plasma MDA (malondialdehyde) and TAC (total antioxidative capacity) status, erythrocyte GSH content and SOD (superoxide dismutase) activity were determined. A comet assay was employed to evaluate DNA damage. Compared with subjects with NGT, patients with IGR had reduced erythrocyte SOD activity. Patients with diabetes had a higher plasma MDA concentration, but a lower plasma TAC level and erythrocyte SOD activity, than the NGT group. Correlation analysis revealed a strong positive association between IR (insulin resistance) and MDA concentration, but negative correlations with TAC status and SOD activity. With respect to beta-cell function, a positive association with TAC status and an inverse correlation with GSH respectively, were observed. The comet assay revealed slight DNA damage in patients with IGR, which was increased in patients with diabetes. Significant correlations were observed between DNA damage and hyperglycaemia, IR and beta-cell dysfunction. In conclusion, the results of the present study suggest that hyperglycaemia in an IGR state caused the predominance of oxidative stress over antioxidative defence systems, leading to oxidative DNA damage, which possibly contributed to pancreatic beta-cell dysfunction, IR and more pronounced hyperglycaemia. This vicious circle finally induced the deterioration to diabetes.

Resveratrol reduces vascular cell senescence through attenuation of oxidative stress by SIRT1/NADPH oxidase-dependent mechanisms

OBJECTIVEnSenescence of vascular cells contributes to the development of cardiovascular diseases and the overall aging. This study was undertaken to investigate the effects of resveratrol (Res) on amelioration of vascular cell aging and the role of SIRT1/nicotinamide adenine dinucleotide phosphate (NADPH) oxidase pathway.nnnMETHODS AND RESULTSnAdult male Wistar rats were treated with a high-fat/sucrose diet (HFS) in the presence or absence of Res for 3 months. HFS and in vitro treatment with high glucose increased the senescence cells and reactive oxygen species production in rat aorta and cultured bovine aortic endothelial cells (BAECs), respectively, which was attenuated by Res treatment. Res protected against HFS- or high-glucose-induced increase in NADPH oxidase p47phox expression and decrease in SIRT1 level. Apocynin, a NADPH oxidase inhibitor, down-regulated p47phox protein expression, but had no influence on SIRT1 protein; sirtinol, a SIRT1 inhibitor, aggravated the decrease in SIRT1 protein level and the increase in p47phox protein expression induced by high glucose.nnnCONCLUSIONnOur studies suggested that Res was able to reverse the senescence process in aorta induced by HFS in rats or induced by the exposure to high glucose in cultured BAECs. The underlying mechanism is at least SIRT1/NADPH oxidase pathway dependent.

The effect of health and nutrition education intervention on women's postpartum beliefs and practices: a randomized controlled trial

BackgroundSitting month is the Chinese tradition for postpartum customs. Available studies indicate that some of the traditional postpartum practices are potentially harmful for womens health. However, no intervention study aiming at postpartum practices has been performed. In this paper we evaluated the effect of a health and nutrition education intervention, which focused on improving postpartum dietary quality and optimal health behaviors.MethodsThe study design was a randomized controlled trial conducted in both urban and rural area of Hubei between August 2003 and June 2004. A total of 302 women who attended the antenatal clinic during the third trimester with an uncomplicated pregnancy were recruited. Women randomized to the education intervention group in both urban and rural area received two two-hour prenatal education sessions and four postpartum counseling visits. Control group women received usual health care during pregnancy and postpartum period. Women were followed up until 42 days postpartum. Outcome measures were nutrition and health knowledge, dietary behavior, health behavior and health problems during the postpartum period.ResultsWomen in the intervention groups exhibited significantly greater improvement in overall dietary behaviors such as consumption of fruits, vegetables, soybean and soybean products as well as nutrition and health knowledge than those in the control groups. Significantly more women in the intervention groups give up the traditional behavior taboos. The incidence of constipation, leg cramp or joint pain and prolonged lochia rubra was significantly lower in the intervention groups as compared with the control groups.ConclusionThe study shows that health and nutrition education intervention enable the women take away some of the unhealthy traditional postpartum practices and decrease the prevalence of postpartum health problems. The intervention has potential for adaptation and development to large-scale implementation.Trial registration numberklACTRN12607000549426

Green tea polyphenols down-regulate caveolin-1 expression via ERK1/2 and p38MAPK in endothelial cells.

Caveolin-1 (Cav-1), a negative regulator of endothelial nitric oxide synthase (eNOS), influences various aspects of the cardiovascular functions. We had reported that a high-fat diet up-regulated aortic Cav-1 expressions in rats. In this study, we investigated the effects of green tea polyphenols (GTPs) on endothelial Cav-1 expression and phosphorylation in vitro. Bovine aortic endothelial cells (BAECs) were treated with 4 microg/ml GTPs for 0, 4, 8, 12, 16 and 24 h, and with 0, 0.04, 0.4, 4 and 40 microg/ml GTPs for 16 h, respectively. Cav-1 protein and mRNA were detected using Western blot and reverse transcriptase polymerase chain reaction. Cav-1 protein expression was down-regulated after treatment of BAECs with 4 microg/ml GTPs for 12, 16 and 24 h. And decrease in the level of Cav-1 mRNA was observed after GTP treatment for 4 and 8 h. GTPs (0.04-4 microg/ml) down-regulate Cav-1 protein expressions and mRNA levels dose dependently. PD98059, an inhibitor of extracellular signal-regulated kinase 1/2 (ERK1/2), up-regulated Cav-1 expression in BAECs alone and abolished the down-regulation effects of GTPs in BAECs while pretreatment with it. Inhibition of p38 mitogen-activated protein kinase (p38MAPK) with SB203580, which down-regulates Cav-1 expression in BAECs alone, deteriorated the Cav-1 down-regulating effects by GTPs. In addition to the effects on expression of Cav-1, GTP treatment inhibited phosphorylation of Cav-1 [tyrosine 14 (Tyr14)]. These data indicate that GTPs down-regulate gene expression of Cav-1 time- and dose- dependently via activating ERK1/2 and inhibiting p38MAPK signaling.

Chronic leucine supplementation increases body weight and insulin sensitivity in rats on high-fat diet likely by promoting insulin signaling in insulin-target tissues.

SCOPEnThis study investigated the effect of chronic leucine supplementation on insulin sensitivity and the associated mechanisms in rats on high-fat diet (HFD).nnnMETHODS AND RESULTSnMale Sprague-Dawley rats were fed either normal chow diet or HFD supplemented with 0, 1.5, 3.0, and 4.5% leucine for 24xa0weeks. We found that chronic leucine supplementation increased insulin sensitivity together with increased body weight in rats on HFD, but had no effect on insulin sensitivity in rats on normal chow diet. The increased insulin sensitivity by leucine supplementation was not associated with altered ectopic fat accumulation in liver and muscle, plasma levels of lipids and cytokines, but is associated with reduced oxidative stress and improved insulin signaling. Chronic leucine supplementation did not enhance insulin receptor substract-1 (IRS-1) phosphorylation on serine 302, but elevated basal IRS-1 phosphorylation on tyrosine 632 and improved insulin-stimulated protein kinase B (Akt) and mammalian target of rapamycin (mTOR) phosphorylation in liver, skeletal muscle, and adipose tissue of rats on HFD rats, indicating leucine supplementation prevented HFD-induced insulin resistance in insulin-target tissues.nnnCONCLUSIONnChronic leucine supplementation can increase insulin sensitivity and body weight likely by reducing oxidative stress and improving insulin signaling pathway in rats on HFD.

Ginkgo biloba Extract Prevents Ethanol Induced Dyslipidemia

Ginkgo biloba extract (EGB) functions as a natural substantial antioxidant and hypolipidemic. Chronic alcohol abuse leads to sustained dyslipidemia characterized by hyperlipidemia and lipid peroxidation. Thus, the present study investigates the effect of EGB on lipid disorders induced by ethanol in rats. Male Sprague-Dawley rats were fed with ethanol (2.4 g/kg), and pretreated with a daily dose of low or high EGB (48 or 96 mg/kg, respectively). During the experiment, serum was collected on day 30, 60, and 90. Serum lipid profile, including lipid peroxidation, was determined by colorimetric methods. Our data showed that ethanol intake resulted in a time-dependent increase in serum levels of triglyceride (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C) and malondialdehyde (MDA), and a decrease of the ratio of high-density lipoprotein cholesterol (HDL-C) against TC. EGB prophylactic medication (48 and 96 mg/kg), especially at the high dose, significantly increased HDL-C content, and normalized the abnormal lipid profile and peroxidation in comparison to ethanol-fed only rats. These results suggest that ethanol results in time-dependent hypercholesterolemia, hypertriglyceridemia and promotes serum lipid peroxidation. EGB pretreatment prevents hyperlipidemia and ameliorates lipid peroxidation induced by ethanol.

Lutein Prevents High Fat Diet-Induced Atherosclerosis in ApoE-Deficient Mice by Inhibiting NADPH Oxidase and Increasing PPAR Expression

Epidemiological and experimental studies provide supportive evidence that lutein, a major carotenoid, may act as a chemopreventive agent against atherosclerosis, although the underlying molecular mechanisms are not well understood. The main aim of this study was to investigate the effects of lutein on the alleviation of atherosclerosis and its molecular mechanisms involved in oxidative stress and lipid metabolism. Male apolipoprotein E knockout mice (nxa0=xa055) were fed either a normal chow diet or a high fat diet (HFD) supplemented with or without lutein for 24xa0weeks. The results showed that a HFD induced atherosclerosis formation, lipid metabolism disorders and oxidative stress, but noticeable improvements were observed in the lutein treated group. Additionally, lutein supplementation reversed the decreased protein expression of aortic heme oxygenase-1 and increased the mRNA and protein expressions of aortic nicotinamide-adenine dinucleotide phosphate oxidase stimulated by a HFD. Furthermore, the decreased mRNA and protein expression levels of hepatic peroxisome proliferator-activated receptor-α, carnitine palmitoyltransferase 1A, acyl CoA oxidase 1, low density lipoprotein receptors and scavenger receptor class B type I observed in mice with atherosclerosis were markedly enhanced after treatment with lutein. Taken together, these data add new evidence supporting the anti-atherogenic properties of lutein and describing its mechanisms of action in atherosclerosis prevention, including oxidative stress and lipid metabolism improvements.

Alteration of Lipid Profile in Subclinical Hypothyroidism: A Meta-Analysis

Background Previous studies yielded controversial results about the alteration of lipid profiles in patients with subclinical hypothyroidism. We performed a meta-analysis to investigate the association between subclinical hypothyroidism and lipid profiles. Material/Methods We searched PubMed, Cochrane Library, and China National Knowledge Infrastructure articles published January 1990 through January 2014. Dissertation databases (PQDT and CDMD) were searched for additional unpublished articles. We included articles reporting the relationship between subclinical hypothyroidism and at least 1 parameter of lipid profiles, and calculated the overall weighted mean difference (WMD) with a random effects model. Meta-regression was used to explore the source of heterogeneity among studies, and the Egger test, Begg test, and the trim and fill method were used to assess potential publication bias. Results Sixteen observational studies were included in our analysis. Meta-analysis suggested that the serum total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and total triglyceride levels were significantly increased in patients with subclinical hypothyroidism compared with euthyroidism individuals; the WMD were 12.17 mg/dl, 7.01 mg/dl, and 13.19 mg/dl, respectively (P<0.001 for all). No significant difference was observed for serum high-density lipoprotein cholesterol (HDL-C). Match strategy was the main source of heterogeneity among studies in TC and LDL-C analysis. Potential publication bias was found in TC and LDL-C analysis by the Egger test or Begg test and was not confirmed by the trim and fill method. Conclusions Subclinical hypothyroidism may correlate with altered lipid profile. Previous studies had limitations in the control of potential confounding factors and further studies should consider those factors.

Resveratrol ameliorates high-glucose-induced hyperpermeability mediated by caveolae via VEGF/KDR pathway

Endothelial hyperpermeability induced by hyperglycemia is the initial step in the development of atherosclerosis, one of the most serious cardiovascular complications in diabetes. In the present study, we investigated the effects of resveratrol (RSV), a bioactive ingredient extracted from Chinese herb rhizoma polygonum cuspidatum, on permeability in vitro and the molecular mechanisms involved. Permeability was assessed by the efflux of fluorescein isothiocyanate (FITC)-dextran permeated through the monolayer endothelial cells (ECs). The mRNA levels, protein expressions, and secretions were measured by quantitative real-time PCR, western blot, and ELISA, respectively. Increased permeability and caveolin-1 (cav-1) expression were observed in monolayer ECs exposed to high glucose. Resveratrol treatment alleviated the hyperpermeability and the overexpression of cav-1 induced by high glucose in a dose-dependent manner. β-Cyclodextrin, a structural inhibitor of caveolae, reduced the hyperpermeability caused by high glucose. Resveratrol also down-regulated the increased expressions of vascular endothelial growth factor (VEGF) and kinase insert domain receptor (KDR, or VEGF receptor-2) induced by high glucose. Inhibition of VEGF/KDR pathway by using SU5416, a selective inhibitor of KDR, alleviated the hyperpermeability and the cav-1 overexpression induced by high glucose. The above results demonstrate that RSV ameliorates caveolae-mediated hyperpermeability induced by high glucose via VEGF/KDR pathway.

The diabetogenic effects of excessive ethanol: reducing β-cell mass, decreasing phosphatidylinositol 3-kinase activity and GLUT-4 expression in rats.

The diabetogenic impact of ethanol remains as a focal point of basic and clinical investigations. In this study, Wistar rats were subjected to daily intragastric ethanol administration (10 ml/kg body weight injection with 0 (control), 10, 20 and 33 % (v/v) ethanol in the injections, respectively) for 19 weeks. At the end of the administration, we found that the fasting plasma glucose level of the 33 % (v/v) ethanol-loaded group was 18 % higher than the control. Insulin sensitivity was decreased in a dose-dependent manner in all the ethanol-loaded groups (r - 0.842, P < 0.001) during intraperitoneal insulin tolerance test. Necrotic/haemorrhagic injury was detected in the pancreas and islet beta-cell mass was significantly reduced in the 33 % (v/v) ethanol-loaded rats by immunohistochemical and morphometric analysis. At the molecular level, we detected a dose-dependent attenuation of phosphatidylinositol 3-kinase activity (r - 0.956, P < 0.001) and GLUT-4 expression (GLUT-4 mRNA, r - 0.899, P < 0.001; GLUT-4 protein, r - 0.964, P < 0.001) in skeletal muscle. These results demonstrated that drinking is a conditional aetiological factor for diabetes and excessive ethanol intake is negatively associated with both insulin sensitivity and beta-cell mass. The whole-body insulin resistance might result from the ethanol-induced insulin signalling defects in muscle.