Apoptosis and oxidative status in peripheral blood mononuclear cells of diabetic patients

We have compared the concentrations of intracellular glutathione (GSH), glutathione-dependent antioxidative enzymes, the cell death rate and immunophenotype profile of peripheral blood mononuclear cells (PBMC) from healthy donors and from patients with insulin-dependent type I (IDDM) or non insulin-dependent type II (NIDDM) diabetes mellitus. The IDDM and NIDDM patients had above-normal absolute lymphocyte counts, whereas the percentages of CD3, CD4 and CD8 T lymphocytes were significantly reduced. In contrast, the absolute number and percentage of B lymphocytes was higher in diabetic patients than in healthy donors. The low intracellular reduced glutathione (GSH) and the unbalanced profile of key enzymes involved in GSH metabolism, gamma glutamyltransferase (-GT) and glutathione-S-transferase (GST), account for the increased oxidative status of PBMC from diabetic patients. The plasma membranes of PBMC from diabetic patients were less permeable to propidium iodide than those of PBMC from healthy donors, indicating that the apoptotic cell death rate was lower in the cells from diabetic patients. These differences are potentially useful markers of pathogenic metabolic changes which occur during clinical diabetes and if they are confirmed could be used to identify the onset of diabetes.     

Effect of enteral nutritional products differing in carbohydrate and fat on indices of carbohydrate and lipid metabolism in patients with NIDDM

Non-insulin dependent diabetes mellitus (NIDDM) is associated with chronic hyperglycemia, which increases the risk of developing microvascular and macrovascular complications. Elevated triglyceride (TG) and VLDL cholesterol levels and low levels of HDL cholesterol have also been frequently reported in NIDDM patients. A diet high in complex carbohydrate and low in fat is typically recommended for management of NIDDM, however, this has recently been challenged by scientific reports of the benefits of dietary intakes high in monounsaturated fat. Thirty-two individuals with NIDDM were randomized to receive either Ensure with Fibre® (30% fat) or a high monounsaturated fatty acid product, Glucerna® (50% fat). These products were consumed for 28 days at 280% of daily energy intake. Post-treatment, dietary compliance was verified by a higher plasma TG 18:1 n-9 (p < 0.001) in the Glucerna® group and a higher plasma TG 18:2 n-6 (p < 0.001) in the Ensure with Fibre® group. The postprandial rise in blood glucose levels, determined by fingerprick samples, was significantly lower (p < 0.01) in the Glucerna® group. Trends of clinical interest were greater mean decreases in the Glucerna® group compared to the Ensure with Fibre® group in: fructosamine, 9.13 umol/L vs 0.14 umol/L; glucose, 1.61 mmol/L vs 0.63 mmol/L; and insulin, 46.0 pmol/L vs 12.6 pmol/L; respectively. However, overall, fasting plasma glucose, fructosamine, TG and cholesterol levels were not significantly different between groups. Thus, in these patients, the high monounsaturated fat diet and the standard diet were similar with regard to usual indicators of carbohydrate and lipid metabolism. A high monounsaturated fat diet appears to pose no risk to lipoprotein metabolism in NIDDM patients.     

Assessment of copper and zinc status in hair and urine of young women descendants of NIDDM parents

The concentration of copper (Cu) and zinc (Zn) in hair and urine were studied in young nonpregnant healthy women whose both parents were diagnosed for noninsulin-dependent diabetes mellitus (NIDDM descendants) and were compared with those of young healthy nonpregnant females with no family history of NIDDM or hypertension (non-NIDDM descendants) and NIDDM patients. The concentration of Zn in hair in NIDDM descendants was significantly higher than that of non-NIDDM descendants (p < 0.001) and insignificantly higher than that of NIDDM patients. The hair Cu concentrations in NIDDM descendant and patients were significantly lower than that of non-NIDDM descendants (p < 0.001). Hyperzincuria was detected in some NIDDM patients and hypocuperuria in all NIDDM descendants and patients. The data suggest that the young healthy NIDDM descendants possess high-Zn and low-Cu reserves in their bodies, and the observed perturbation appears to be associated with Cu-Zn antagonism.     

The Male Obese Wistar Diabetic Fatty Rat Is a New Model of Extreme Insulin Resistance

The male obese Wistar Diabetic Fatty (WDF) rat is a genetic model of obesity and non-insulin dependent diabetes (NIDDM). The obese Zucker rat shares the same gene for obesity on a different genetic background but is not diabetic. This study evaluated the degree of insulin resistance in both obese strains by examining the binding and post binding effects of muscle insulin receptors in obese, rats exhibiting hyperinsulinemia and/or hyperglycemia. Insulin receptor binding and affinity and tyrosine kinase activity were measured in skeletal muscle from male WDF fa/fa (obese) and Fa/? (lean) and Zucker fa/fa (obese) and Fa/Fa (homozygous lean) rats. Rats were fed a high sucrose (68% of total Kcal) or Purina stock diet for 14 weeks. At 27 weeks of age, adipose depots were removed for adipose cellularity analysis and the biceps femoris muscle was removed for measurement of insulin binding and insulin-stimulated receptor kinase activity. Plasma glucose (13.9 vs. 8.4 mM) and insulin levels (14,754 vs. 7440 pmoI/L) were significantly higher in WDF obese than in Zucker obese rats. Insulin receptor number and affinity and TK activity were unaffected by diet. Insulin receptor number was significantly reduced in obese WDF rats (2.778 ± 0.617 pmol/mg protein), compared to obese Zucker rats (4.441 ± 0.913 pmol/mg potein). Both obese strains exhibited down regulation of the insulin receptor compared to their lean controls. Maximal tyrosine kinase (TK) activity was significantly reduced in obese WDF rats (505 ± 82 fmol/min/mg protein) compared to obese Zucker rats (1907 ± 610 fmol/min/mg protein). Only obese WDF rats displayed a decrease in TK activity per receptor. These observations establish the obese WDF rat as an excellent model for exploring mechanisms of extreme insulin resistance, particularly post-receptor tyrosine kinase-associated defects, in non-insulin dependent diabetes.     

诺沙坦改善非胰岛素依赖型糖尿病大鼠胰岛素敏感性的作用机制

本文研究血管紧张素Ⅱ受体拮抗剂诺沙坦对非胰岛素依赖型糖尿病(non-insulin-dependent diabetes mellitus,NIDDM)大鼠胰岛素敏感性的改善作用,并探讨其作用机制。从饮水中给予正常或高脂喂养加小剂量链脲佐菌素(STZ)诱发的NIDDM大鼠诺沙坦(4 mg/kg),连续6周。分离骨骼肌,用免疫印迹法检测诺沙坦对胰岛素受体底物1(insulin receptor substrate 1,IRS-1)、蛋白激酶B(protein kinase B,PKB)和葡萄糖转运因子4(glucose transporter 4,GLUT4)的表达,以及IRS-1的磷酸化、IRS-1与磷脂酰肌醇3激酶(phosphatidylinositol(PI)3-kinase)的结合。口服葡萄糖耐量试验表明,口服诺沙坦可改善糖尿病大鼠胰岛素敏感性。在骨骼肌组织,NIDDM和正常大鼠的IRS-1、PKB和GLUT4蛋白表达无差异,且不受诺沙坦处理的影响。NIDDM大鼠胰岛素刺激后的骨骼肌IRS-1酪氨酸磷酸化水平、PI 3-kinase结合IRS-1的活性和PKB活性较对照组显著降低(P<0.01),且不能被诺沙坦改善。诺沙坦显著增加NIDDM大鼠肌细胞质膜(plasma membrane,PM)和T管(T-tubules,TT)胰岛素诱导的GLUT4的 含量(P<0.05)。与该结果一致的是,诺沙坦处理的NIDDM大鼠血糖水平较未处理NIDDM大鼠下降(P<0.05)。结果表明,诺沙坦可改善胰岛素抵抗状态,主要是通过非PI 3-kinase依赖的     

NIDDM病人空腹血糖遗传度分析

应用数量性状遗传度估计方法(相关回归法), 对50户NIDDM病例核心家庭成员空腹血糖的遗传度进行估计,以探讨遗传和环境因素对血糖这一数量性状的决定作用。结果表明,经年龄和环境因素校正血糖后,用子女对中亲回归估计的空腹血糖遗传度为0.35768±0.2024, 说明遗传因素虽起一定作用,但环境因素的作用更不容忽视,即支持NIDDM为多因子遗传病。空腹血糖的遗传未显示母体效应。 Abstract:The heritabiligy of fasting glucose was estimated on the members of 50 core families by using the method of correlation and regression of quantitative character heritability so as to research the role of genetic and environmental factors in NIDDM.The result showed that the heritability of glucose,adjusted by age and environmental factors,of the offspring on mid-parent was 0.35768±0.2024.This suggested that in NIDDM genetic factors play a role to some extent,but the influence of environmental factors is more significant,i.e. NIDDM being considered as a multifactorial disease.The genetics of fasting glucose did not show the maternal effects.     

Alterations in glucose transporter expression and function in diabetes: mechanisms for insulin resistance.

Insulin resistance is a major pathologic feature of human obesity and diabetes. Understanding the fundamental mechanisms underlying this insulin resistance has been advanced by the recent cloning of the genes encoding a family of facilitated diffusion glucose transporters which are expressed in characteristic patterns in mammalian tissues. Two of these transporters, GLUT1 and GLUT4, are present in muscle and adipose cells, tissues in which glucose transport is markedly stimulated by insulin. To understand the mechanisms underlying in vivo insulin resistance, regulation of these transporters is being investigated. Studies reveal divergent changes in the expression of GLUT1 and GLUT4 in a single cell type as well as tissue specific regulation. Importantly, alterations in glucose transport in rodent models of diabetes and in human obesity and diabetes cannot be entirely explained by changes in glucose transporter expression. This suggests that defects in glucose transporter function such as impaired translocation, fusion with the plasma membrane, or activation probably contribute importantly to in vivo insulin resistance.     

NIDDM新候选基因KCNA7的cSNP在东北人群中的分布及意义

为研究NIDDM新候选基因KCNA7的cSNP在东北人群中的分布及意义,本实验采用PCR-RFLP技术检测了97例NIDDM患者、141例健康对照者KCNA7基因418M（C/T）多态;并利用SSCP技术筛查了该位点附近其他未知SNP。发现CNA7 基因T418M（C/T）基因型频率在正常人群中分布符合Hardy-Weinberg平衡,基因频率和基因型频率在NIDDM组和正常对照组中分布无显著性差异（P＞0.05）;NIDDM组和正常对照组中各基因型间临床生化指标无显著性差异;该位点附近尚未发现其他SNP。结果提示,T418M（C/T）仅为KCNA7基因多态性标志,但不排除KCNA7基因其余结构变异与NIDDM存在相关性的可能。     

Hypercytolipidemia-induced cellular lipoapoptosis: cytostructural and endometabolic basis of progressive organo-involution following expression of diabetes (db/db) and obese (ob/ob) mutation syndromes

Onset expression of Type 2 (NIDDM) diabetes and obesity metabolic syndromes (DOS) are characterized by premature, progressive cytoatrophy and organo-involution induced by dysregulated cellular gluco- and lipo-metabolic cascades. The consequential systemic, interstitial and intracellular hyperlipidemia disrupts normal cytointegrity and metabolic responsivity to the established hypercaloric pericellular environments. The sequential cytostructural, metabolic and endocrine disturbances associated with the development of progressive DOS-associated hypercytolipidemia compromises cellular metabolic response cascades and promotes cytochemical disturbances which culminate with nuclear lipoapoptosis and cytoatrophy. The dramatic alterations in interstitial glucose and lipid (free fatty acids/triglycerides) concentrations are recognized to influence interstitial and cytoplasmic microchemical environments, which markedly alter cellular nutrient diffusion and active trans-membrane flux rates. The progressive exacerbation of interstitial and cytoplasmic lipid imbibition has been demonstrated to be associated with DNA fragmentation by lipo-infiltration into the chromatin matrix, inducing structural disruption and physical dissolution, indexed as nuclear lipoapoptosis. Therapeutic reduction of the severity of hypercytolipidemia-induced structural and cytochemical compromise promotes the restoration of homeostatic metabolic support for normalized cytostructural indices and supportive cellular gluco- and lipo-metabolic cascades. The re-establishment of a homeostatic interstitial microenvironment moderates the severity of cytolipidemic compromise within affected cell types, reduces nuclear lipo-infiltration and DNA lipo-dissolution, resulting in the preservation of cytostructural integrity. Through the therapeutic restoration of extra- and intra-cellular microchemical environments in genetically dysregulated metabolic syndrome models, the coincident cytochemical, endocrine and metabolic disturbances associated with progressive hypercytolipidemia, resulting from the expressed systemic hypercaloric environmental and hepato-pancreatic endometabolic disturbances which characterize Type 2 (NIDDM) diabetes–obesity and metabolic (X) syndromes, may be ameliorated.     

3β-taraxerol of Mangifera indica, a PI3K dependent dual activator of glucose transport and glycogen synthesis in 3T3-L1 adipocytes

Background

The present study focuses on identifying and developing an anti-diabetic molecule from plant sources that would effectively combat insulin resistance through proper channeling of glucose metabolism involving glucose transport and storage.

Methods

Insulin-stimulated glucose uptake formed the basis for isolation of a bioactive molecule through column chromatography followed by its characterization using NMR and mass spectroscopic analysis. Mechanism of glucose transport and storage was evaluated based on the expression profiling of signaling molecules involved in the process.

Results

The study reports (i) the isolation of a bioactive compound 3β-taraxerol from the ethyl acetate extract (EAE) of the leaves of Mangifera indica (ii) the bioactive compound exhibited insulin-stimulated glucose uptake through translocation and activation of the glucose transporter (GLUT4) in an IRTK and PI3K dependent fashion. (iii) the fate of glucose following insulin-stimulated glucose uptake was ascertained through glycogen synthesis assay that involved the activation of PKB and suppression of GSK3β.

General significance

This study demonstrates the dual activity of 3β-taraxerol and the ethyl acetate extract of Mangifera indica as a glucose transport activator and stimulator of glycogen synthesis. 3β-taraxerol can be validated as a potent candidate for managing the hyperglycemic state.