Experimental Diabetes Research最新文献

Background: Apelin, the endogenous ligand for the APJ receptor, has a potent hypotensive effect via a nitric oxide-dependent mechanism in vivo. The aim of the study was to investigate the association between the common variants of apelin gene (APLN) and hypertension, which was reported recently in a Chinese Han population with and without diabetes.

Methods: Three single nucleotide polymorphisms (SNPs) on APLN were genotyped in 3156 diabetic patients and 3736 nondiabetic individuals. For non-diabetic subjects, 1779 were enrolled in stage 1 and 1757 were recruited for validation. A meta-analysis combining the two stages was carried out to obtain the overall effect.

Results: In diabetic patients, no significant associations of the three SNPs with hypertension were observed. In contrast, we found that rs2235306 was associated with hypertension in non-diabetic males after adjusting for covariates (OR = 1.19, P = 0.039) while rs2235307 and rs3115759 displayed no evidence of association in both genders. One haplotype, C-C-A, also showed an association with hypertension (OR = 1.47, P = 0.032) only in men. However, analysis in stage 2 and meta-analysis did not support these findings.

Conclusions: We conclude that common variants on APLN are not associated with the prevalence of hypertension in the Chinese.

Objectives: The aim of this study was to evaluate the prevalence and the risk factors of prolonged QTc interval among Chinese patients with type 2 diabetes.

Methods: The retrospective study included 3156 outpatients from the Diabetes Centre, the 306th Hospital of PLA, during the period from September 2003 to June 2010. QT interval was measured manually in the 12-lead conventional electrocardiogram. The QT interval corrected for heart rate (QTc) was calculated using Bazett's formula. Additional demographic and laboratory data were also collected. Potential risk factors of prolonged QTc interval were assessed using multivariable regression.

Results: The prevalence of prolonged QTc interval among Chinese patients with type 2 diabetes was 30.1%. Height (OR 0.156, 95% CI 0.032~0.748), waist circumference (OR 1.025, 95% CI 1.010~1.040), diastolic blood pressure (OR 1.016, 95% CI 1.007~1.026), postprandial glucose (OR 1.040, 95% CI 1.022~1.059), fasting insulin (OR 1.014, 95% CI 1.003~1.025), and presence of microalbuminuria (OR 1.266, 95% CI 1.033~1.551) were significant risk factors.

Conclusions: The prevalence of prolonged QTc interval among Chinese patients with type 2 diabetes is high. Risk factors for prolongation of QTc interval were low height, high waist circumference, increasing diastolic blood pressure levels, high postprandial glucose levels, high fasting insulin levels, and presence of microalbuminuria.

Diabetes and smoking are known risk factors for cataract development. In this study, we evaluated the effect of nicotine on the progression of cataracts in a type 1 diabetic rat model. Diabetes was induced in Sprague-Dawley rats by a single injection of 65 mg/kg streptozotocin. Daily nicotine injections were administered subcutaneously. Forty-five rats were divided into groups of diabetics with and without nicotine treatment and controls with and without nicotine treatment. Progression of lens opacity was monitored using a slit lamp biomicroscope and scores were assigned. To assess whether systemic inflammation played a role in mediating cataractogenesis, we studied serum levels of eotaxin, IL-6, and IL-4. The levels of the measured cytokines increased significantly in nicotine-treated and untreated diabetic animals versus controls and demonstrated a positive trend in the nicotine-treated diabetic rats. Our data suggest the presence of a synergistic relationship between nicotine and diabetes that accelerated cataract formation via inflammatory mediators.

BACKGROUND AND AIMS. Dysregulation of Akt has been implicated in diseases such as cancer and diabetes, although little is known about the role of Akt deficiency on cardiomyocyte contractile function. This study was designed to examine the effect of Akt2 knockout-induced cardiomyocyte contractile response and the effect of dietary supplementation of short-chain fatty acid propionate on Akt2 knockout-induced cardiac dysfunction, if any. METHODS AND RESULTS. Adult male wild-type (WT) and Akt2 knockout mice were treated with propionate (0.3 g/kg, p.o.) or vehicle for 7 days. Oral glucose tolerance test (OGTT) was performed. Cardiomyocyte contractile function and mitochondrial membrane potential were assessed. Expression of insulin-signaling molecules Akt, PTEN, GSK3β, and eNOS receptors for short-chain fatty acids GPR41, and GPR43 as well as protein phosphatase PP2AA, PP2AB, PP2C were evaluated using Western blot analysis. Our results revealed that Akt2 knockout led to overt glucose intolerance, compromised cardiomyocyte contractile function (reduced peak shortening and maximal velocity of shortening/relengthening as well as prolonged relengthening), loss of mitochondrial membrane potential, decreased GPR41 and elevated GPR43 expression, all of which, with the exception of glucose intolerance and elevated GPR43 level, were significantly attenuated by propionate. Neither Akt2 knockout nor propionate affected the expression of protein phosphatases, eNOS, pan, and phosphorylated PTEN and GSK3β. CONCLUSIONS. Taken together, these data depicted that Akt2 knockout may elicit cardiomyocyte contractile and mitochondrial defects and a beneficial role of propionate or short-chain fatty acids against Akt2 deficiency-induced cardiac anomalies.

Diabetic patients have a higher risk of various types of cancer. However, whether diabetes may increase the risk of thyroid cancer has not been extensively studied. This paper reviews and summarizes the current literature studying the relationship between diabetes mellitus and thyroid cancer, and the possible mechanisms linking such an association. Epidemiologic studies showed significant or nonsignificant increases in thyroid cancer risk in diabetic women and nonsignificant increase or no change in thyroid cancer risk in diabetic men. A recent pooled analysis, including 5 prospective studies from the USA, showed that the summary hazard ratio (95% confidence interval) for women was 1.19 (0.84-1.69) and was 0.96 (0.65-1.42) for men. Therefore, the results are controversial and the association between diabetes and thyroid cancer is probably weak. Further studies are necessary to confirm their relationship. Proposed mechanisms for such a possible link between diabetes and thyroid cancer include elevated levels of thyroid-stimulating hormone, insulin, glucose and triglycerides, insulin resistance, obesity, vitamin D deficiency, and antidiabetic medications such as insulin or sulfonylureas.

Gestational diabetes, occurring during the hyperglycemic period of pregnancy in maternal life, is a pathologic state that increases the incidence of complications in both mother and fetus. Offspring thus exposed to an adverse fetal and early postnatal environment may manifest increased susceptibility to a number of chronic diseases later in life. Compelling evidence for the role of epigenetic transmission in these complications has come from comparison of siblings born before and after the development of maternal diabetes, exposure to this intrauterine diabetic environment being shown to cause alterations in fetal growth patterns which predispose these infants to developing overweight and obesity later in life. Diabetes of the offspring is also mainly the consequence of exposure to the diabetic intrauterine environment, in addition to genetic susceptibility. Since obesity and diabetes are known to increase the risk of cardiovascular disease, cardiovascular sequelae in the offspring of diabetic mothers are virtually inevitable. Research data also suggest that exposure to a diabetic intrauterine environment during pregnancy is associated with an increase in dyslipidemia, subclinical vascular inflammation, and endothelial dysfunction processes in the offspring, all of which are linked with development of cardiovascular disease later in life. The main underlying mechanisms involve persistent hyperglycemia hyperinsulinemia and leptin resistance.

The therapeutic success of peptide glucagon-like peptide-1 (GLP-1) receptor agonists for the treatment of type 2 diabetes mellitus has inspired discovery efforts aimed at developing orally available small molecule GLP-1 receptor agonists. Although the GLP-1 receptor is a member of the structurally complex class B1 family of GPCRs, in recent years, a diverse array of orthosteric and allosteric nonpeptide ligands has been reported. These compounds include antagonists, agonists, and positive allosteric modulators with intrinsic efficacy. In this paper, a comprehensive review of currently disclosed small molecule GLP-1 receptor ligands is presented. In addition, examples of "ligand bias" and "probe dependency" for the GLP-1 receptor are discussed; these emerging concepts may influence further optimization of known molecules or persuade designs of expanded screening strategies to identify novel chemical starting points for GLP-1 receptor drug discovery.

The present study investigates the relationship between diabetes metabolic control represented by levels of HbA1c, early glycation products-(fructosamine (FAM)), serum-advanced glycation end products (s-AGEs), lipoperoxidation products (LPO), advanced oxidation protein products (AOPP) and circulating TGF-β in young patients with DM1. The study group consisted of 79 patients with DM1 (8-18 years). 31 healthy children were used as control (1-16 years). Baseline characteristics of patients were compared by Student's t-test and nonparametric Mann-Whitney test (Statdirect), respectively. The correlations between the measured parameters were examined using Pearson correlation coefficient r and Spearman's rank test, respectively. A P value < 0.05 was considered as statistically significant. HbA1c was measured by LPLC, s-AGEs spectrofluorimetrically, LPO and AOPP spectrophotometrically and TGF-β by ELISA. Our results showed that parameters of glycation and oxidation are significantly higher in patients with DM1 than in healthy control. The level of serum TGF-β was significantly higher in diabetics in comparison with control: 7.1(3.6; 12.6) versus 1.6(0.8; 3.9) ng/mL. TGF-β significantly correlated with age and duration of DM1. There was not found any significant relation between TGF-β and parameres of glycation and oxidation. However, these results do not exclude the association between TGF-β and the onset of diabetic complications.

Muscle mitochondrial metabolism is a tightly controlled process that involves the coordination of signaling pathways and factors from both the nuclear and mitochondrial genomes. Perhaps the most important pathway regulating metabolism in muscle is mitochondrial biogenesis. In response to physiological stimuli such as exercise, retrograde signaling pathways are activated that allow crosstalk between the nucleus and mitochondria, upregulating hundreds of genes and leading to higher mitochondrial content and increased oxidation of substrates. With type 2 diabetes, these processes can become dysregulated and the ability of the cell to respond to nutrient and energy fluctuations is diminished. This, coupled with reduced mitochondrial content and altered mitochondrial morphology, has been directly linked to the pathogenesis of this disease. In this paper, we will discuss our current understanding of mitochondrial dysregulation in skeletal muscle as it relates to type 2 diabetes, placing particular emphasis on the pathways of mitochondrial biogenesis and mitochondrial dynamics, and the therapeutic value of exercise and other interventions.