Mingtong Xu

The role of G protein-coupled receptor 40 in lipoapoptosis in mouse β-cell line NIT-1

Free fatty acids (FFAs) exert divergent effects on beta-cells. Acute exposure to FFAs stimulates insulin secretion, whereas chronic exposure impairs beta-cell function and induces apoptosis. The G protein-coupled receptor 40 (GPR40) is preferentially expressed in beta-cells and is activated by a wide range of FFAs. In this study, we used small interfering RNA technology and apoptosis assay in mouse beta-cell NIT-1 to address the role of GPR40 in beta-cell lipoapoptosis and function. Results showed that palmitate induced beta-cell apoptosis, which was not mediated through GPR40, whereas oleate protected NIT-1 cells from palmitate-induced lipoapoptosis, which was mediated at least in part through GPR40. Moreover, by detecting the activation of the phosphatidylinositol 3-kinase and MAP kinase (MAPK) pathways, we found that oleate promoted the activation of extracellular signal-regulated protein kinase-MAPK pathway mainly via GPR40, increased the expression of early growth response gene-1, leading to the anti-lipoapoptotic effect on NIT-1 cells. It was suggested that GPR40 might be implicated in the control of beta-cell mass plasticity and GPR40 probably provide a link between obesity and type 2 diabetes.

Serum Gamma - Glutamyltransferase Is Associated with Albuminuria: A Population-Based Study

Background Serum γ - glutamyltransferase (GGT) is implicated in the pathogenesis of endothelial dysfunction and atherosclerosis. Albuminuria is a marker of endothelial damage and correlated with structural and functional integrity of the vasculature. Our objective was to evaluate the association between serum GGT level and prevalence of albuminuria in a Chinese population. Materials and Methods We conducted a population-based cross-sectional study in 9,702 subjects aged 40 years or older. Increased urinary albumin excretion was defined according to the urinary albumin-to-creatinine ratio (ACR) ranges greater or equal than 30 mg/g. Low-grade albuminuria was defined according to the highest quartile of ACR in participants without increased urinary albumin excretion. Results The prevalence of low-grade albuminuria and increased urinary albumin excretion were respectively 23.4% and 6.6% in this population and gradually increased across the sex-specific serum GGT quartiles (all P for trend <0.05). In logistic regression analysis, compared with subjects in the lowest quartile of serum GGT level, the adjusted odds ratios (ORs) in the highest quartile was 1.22 [95% confidence interval (CI), 1.04–1.43] for low-grade albuminuria and 1.55 (95% CI, 1.18–2.04) for increased urinary albumin excretion. In subgroup analysis, significant relationship of serum GGT level with both low-grade albuminuria and increased urinary albumin excretion were detected in women, younger subjects, overweight subjects and in those with hypertension or glomerular filtration rate greater than 90 (all P <0.05). Conclusion Serum GGT level is associated with urinary albumin excretion in middle-aged and elderly Chinese.

Elevated follicular helper T Cells and expression of IL-21 in thyroid tissues are involved in the pathogenesis of Graves’ disease

The follicular helper T cell (Tfh) and IL-21 have been shown to play an important role in many autoimmune diseases. However, less is known about their role in Graves’ disease (GD). This study aimed to investigate the expression of Tfhs and related factors (IL-21, IL-21R, CXCR5, and CXCL13) in GD thyroid tissues and to explore the effect of IL-21 on thyroid follicular cells (TFCs). The expression of Tfh-related factors in GD and normal thyroid tissues was validated using immunohistochemistry, real-time polymerase chain reaction and Western blotting. Confocal microscopy confirmed the presence of Tfh and IL-21R on CD4+T-/CD19+B cell in GD thyroid tissues. Furthermore, the effect of IL-21 on cAMP production in TFCs upon thyroid-stimulating antibody (TSAb) stimulation was also examined by an in vitro bioassay. The increased expression of Tfh-related factors was observed in GD thyroid tissues compared to control subjects. Confocal microscopy further confirmed the presence of Tfhs and the expression of IL-21R on CD4+T cells and CD19+B cells in GD thyroid tissues. Moreover, the expression of IL-21mRNA in GD thyroid tissues was correlated with the levels of thyroid autoantibodies. Additionally, IL-21 could indirectly promote cAMP production upon TSAb stimulation in TFCs when cooperating with lymphocytes, and GD TFCs were more sensitive to IL-21 stimulation than normal TFCs. There is increased expression of Tfhs and related factors (IL-21, IL-21R, CXCR5, and CXCL13) in GD thyroid tissues, and the expression of IL-21mRNA in GD thyroid tissues was found to correlate with the serum levels of thyroid autoantibodies and thyroid hormones. Moreover, IL-21 could indirectly enhance the biological activity of TFCs upon TSAb stimulation when cooperating with lymphocytes in vitro, particularly in GD TFCs, suggesting that Tfh and IL-21 might be involved in the pathogenesis of GD.

One-hour upright posture is an ideal position for serum aldosterone concentration and plasma renin activity measuring on primary aldosteronism screening.

The serum aldosterone concentration (SAC) to plasma renin activity (PRA) ratio (ARR) is considered a useful screening test in the differential diagnosis of essential hypertension (EH) and primary aldosteronism (PA). The purpose of this study is to investigate the variation of ARR and compare the screening efficiency of it under different postures.37 patients with PA and 92 patients with EH were recruited in this study. Blood was sampled for measuring SAC and PRA under conditions of overnight recumbency, keeping upright posture for 1 h, 2 h and 4 h. The variation and screening efficiency of ARR under these conditions were compared according to repeated measured ANOVA and ROC curve analysis.In the EH group, ARR measured under recumbency posture was higher than those measured under keeping upright posture for 1 h and 2 h. In the PA group, there is no statistical difference for ARR between any 2 postures. AUCs of ARR measured under 4 conditions were 0.976, 0.995, 0.988, and 0.974 respectively. Cutoff values were ranging from 24.75 ng/dl per ng/ml/h under keeping upright for 2 h to 69.19 ng/dl per ng/ml/h under overnight recumbercy. ARR measured under keeping upright posture for 1 h produced the best characteristic of screening efficiency.Keeping upright posture for 1 h was the ideal position for ARR measuring and using a cutoff value of 35.90 ng/dl per ng/ml/h will have a sensitivity and specificity of 100.00% and 92.30% respectively.

Effect of losartan on the mRNA expressions of MT3-MMP and TIMP-2 in diabetic kidneys.

BACKGROUND AND OBJECTIVES The renin-angiotensin system plays a critical role in circulatory homoeostasis. Evidence has emerged that suggests a pathologic role for angiotensin II in patients with kidney disease. Losartan is an antagonist of angiotensin II and blocks the angiotensin II type-1 receptor. Thus it may reduce proteinuria and delay the progression of renal disease in diabetic nephropathy. We investigated the effects of losartan on the mRNA expressions of membrane-type3 matrix metalloproteinases (MT3-MMP) and the tissue inhibitor of metalloproteinase-2 (TIMP-2) in diabetic kidneys in order to evaluate degradation and remodeling of the extracellular matrix. METHODS Male Wistar rats were divided into 3 groups. Group A was the control group containing healthy rats (n = 11), group B comprised diabetic rats without any therapy (n = 11), and group C consisted of diabetic rats treated with losartan (n = 9). 24-hr urine samples were collected in order to measure urinary albumin excretion (UAE). After a period of 18 weeks, the kidneys were extracted from all rats in order to measure the mRNA expressions of MT3-MMP, TIMP-2 and transforming growth factor-beta1 (TGF-beta1) by RT-PCR. We also examined the glomerular basement membrane thickening and the mesangial matrix (MM) density (MM area/mesangial area). RESULTS The expression of renal MT3-MMP mRNA in group B (1.37 +/- 0.96) was significantly higher than that in group A (0.75 +/- 0.34, p < 0.05), but also significantly higher than in group C (0.75 +/- 0.30, p < 0.05). Similarly, the mRNA expression of renal TIMP-2 in group B (0.73 +/- 0.37) was significantly increased compared to that in group A (0.32 +/- 0.19, p < 0.05), but also higher than in group C (0.34 +/- 0.17, p < 0.05). In addition, subjects in group B showed abundant TGF-beta1 mRNA expression and UAE compared to groups A and C, as well as significantly higher glomerular basement membrane thickening and MM density (all p < 0.05). CONCLUSIONS We conclude that MT3-MMP and TIMP-2 production in the renal cortex of diabetic kidneys is increased. Losartan can prevent the development of diabetic nephropathy by decreasing MT3-MMP and TIMP2 production in diabetic kidneys.

Interaction Between Lactate and Uric Acid is Associated With a Higher Prevalence of Metabolic Syndrome: A Community-Based Study

BACKGROUND Increased blood lactate or uric acid (UA) levels are associated with an increased risk of metabolic syndrome (MS). The aim of this study was to investigate the effect of an interactive association between blood lactate and UA levels on MS. METHODS This community-based cross-sectional study included 2584 Chinese subjects aged ≥ 18 years. Participants were classified into 3 groups based on lactate or UA level tertiles or into 9 groups based on a combination of lactate and UA level tertiles. RESULTS The serum high-sensitivity C-reactive protein (hs-CRP) and homeostatic model assessment of insulin resistance (HOMA-IR) levels and odds ratios (ORs) for MS increased across the blood lactate or UA level tertiles (all P for trend<0.05). Interactions between lactate and UA with hs-CRP level, HOMA-IR level, and ORs for MS (P<0.05 for all interactions) were also observed. The adjusted ORs for MS in participants in the third tertile of lactate and UA levels, in the third tertile of lactate levels and first tertile of UA levels, and in the first tertile of lactate levels and third tertile of UA levels were 6.02 (95% CI 2.87-12.64, P<0.001), 2.92 (95% CI 1.39-6.10, P=0.005), and 2.70 (95% CI 1.23-5.96, P=0.014), respectively, compared with those in the first tertiles of both lactate and UA levels. CONCLUSION The interaction between lactate and UA is associated with a higher prevalence of MS in the Chinese population.

The intriguing effects of time to glycemic goal in newly diagnosed type 2 diabetes after short-term intensive insulin therapy

Short-term intensive insulin therapy is effective for type 2 diabetes because it offers the potential to achieve excellent glycemic control and improve β-cell function. We observed that the time to glycemic goal (TGG) was adjustable. Original data of 138 newly diagnosed type 2 diabetic patients received intensive insulin therapy by continuous subcutaneous insulin infusion for 2-3 weeks were retrospectively collected. Subjects underwent an intravenous glucose tolerance test (IVGTT) and an oral glucose tolerance test (OGTT) pre and post treatment. The glycemic goal was achieved within 6 (4-8) days. Patients were divided into two groups by TGG above (TGG-slow) and below (TGG-fast) the median value. Patients in both groups had significantly better glycemic control. Compared with TGG-fast, TGG-slow required a few more total insulin and performed more improvement of HOMA-β and IVGTT-AUCIns, but less improvement of HOMA-IR and QUICKI. Multiple linear regression analysis revealed that TGG was always an explanatory variable for the changes (HOMA-β, IVGTT-AUCIns, HOMA-IR and QUICKI). The hypoglycemia prevalence was lower in TGG-slow (1.48% vs. 3.40%, P<0.01). Multivariate logistic regression analysis indicated that individuals in TGG-slow had a lower risk of hypoglycemia (adjusted OR, 0.700; 95% CI, 0.567-0.864; P<0.05). Multiple linear regression analysis confirmed that the ratio of the incremental insulin to glucose responses over the first 30 min during OGTT (ΔIns30/ΔG30), average insulin dose before achieving targets, initial insulin dose and LDL-c were independent predictors for TGG. It is intriguing to hypothesize that patients with fast time to glycemic goal benefit more in improving insulin sensitivity, but patients with slow time benefit more in improving β-cell function and reducing the risk of hypoglycemia.

Dietary glycemic load and metabolic status in newly diagnosed type 2 diabetes in southeastern China

BACKGROUND AND OBJECTIVES Large-scale epidemiological investigations worldwide have shown that dietary glycemic load is associated with metabolic diseases, including diabetes. However, only a few studies have examined the correlations between glycemic load and blood glucose and lipids in Chinese diabetic patients. Therefore, this study aimed to determine these correlations in southeastern China. METHODS AND STUDY DESIGN 201 patients with newly diagnosed type 2 diabetes and 126 participants with normal blood glucose were enrolled at the Sun Yat-sen Memorial Hospital, Guangdong Province. Carbohydrate intake and glycemic load were assessed based on 3-day dietary records. Using glycemic load as the dependent variable, a correlation analysis and multiple regression analyses were used to analyze the correlations between glycemic load and blood glucose and lipids. RESULTS The mean glycemic load in diabetic patients was significantly higher than that in the control group (p<0.05). Correlation analysis showed that glycemic load was positively correlated with body mass index and glycated hemoglobin in diabetic patients (p<0.05) but negatively correlated with high-density lipoprotein cholesterol in all subjects (p<0.05). Multivariable regression analysis indicated that, among participants in southeastern China, a higher glycemic load increased the odds of having diabetes, a low high-density lipoprotein cholesterol, and higher Charlson weighted index of comorbidities score, as well as being overweight. CONCLUSIONS A high-glycemic load diet may be associated with a risk of diabetes, glycemic control, lipid metabolism, prognosis of diseases, and body composition. It is necessary to control dietary glycemic load for both patients with diabetes and healthy people in southeastern China.