Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0011860 (type 2 diabetes)
 57,723 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Oxidative stress is induced under diabetic conditions and possibly causes various forms of tissue damage in patients with diabetes. Recently, it has become aware that susceptibility of pancreatic beta-cells to oxidative stress contributes to the progressive deterioration of beta-cell function in type 2 diabetes. A hypoglycemic sulfonylurea, gliclazide, is known to be a general free radical scavenger and its beneficial effects on diabetic complications have been documented. In the present study, we investigated whether gliclazide could protect pancreatic beta-cells from oxidative damage. One hundred and fifty microM hydrogen peroxide reduced viability of mouse MIN6 beta-cells to 29.3%. Addition of 2 microM gliclazide protected MIN6 cells from the cell death induced by H(2)O(2) to 55.9%. Glibenclamide, another widely used sulfonylurea, had no significant effects even at 10 microM. Nuclear chromatin staining analysis revealed that the preserved viability by gliclazide was due to inhibition of apoptosis. Hydrogen peroxide-induced expression of an anti-oxidative gene heme oxygenase-1 and stress genes A20 and p21(CIP1/WAF1), whose induction was suppressed by gliclazide. These results suggest that gliclazide reduces oxidative stress of beta-cells by H(2)O(2) probably due to its radical scavenging activity. Gliclazide may be effective in preventing beta-cells from the toxic action of reactive oxygen species in diabetes.
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PMID:Gliclazide protects pancreatic beta-cells from damage by hydrogen peroxide. 1264 74

Oxidative stress induced by hyperglycemia possibly causes the dysfunction of pancreatic beta-cells and various forms of tissue damage in patients with diabetes mellitus. Astaxanthin, a carotenoid of marine microalgae, is reported as a strong anti-oxidant inhibiting lipid peroxidation and scavenging reactive oxygen species. The aim of the present study was to examine whether astaxanthin can elicit beneficial effects on the progressive destruction of pancreatic beta-cells in db/db mice--a well-known obese model of type 2 diabetes. We used diabetic C57BL/KsJ-db/db mice and db/m for the control. Astaxanthin treatment was started at 6 weeks of age and its effects were evaluated at 10, 14, and 18 weeks of age by non-fasting blood glucose levels, intraperitoneal glucose tolerance test including insulin secretion, and beta-cell histology. The non-fasting blood glucose level in db/db mice was significantly higher than that of db/m mice, and the higher level of blood glucose in db/db mice was significantly decreased after treatment with astaxanthin. The ability of islet cells to secrete insulin, as determined by the intraperitoneal glucose tolerance test, was preserved in the astaxanthin-treated group. Histology of the pancreas revealed no significant differences in the beta-cell mass between astaxanthin-treated and -untreated db/db mice. In conclusion, these results indicate that astaxanthin can exert beneficial effects in diabetes, with preservation of beta-cell function. This finding suggests that anti-oxidants may be potentially useful for reducing glucose toxicity.
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PMID:Astaxanthin protects beta-cells against glucose toxicity in diabetic db/db mice. 1268 12

Diabetes is the most common cause of erectile dysfunction (ED). Oxidative stress has been suggested to be a contributory factor in vascular complications of diabetes in various organs. In the present study, we investigated whether oxidative stress is associated with erectile function in non-insulin dependent diabetes mellitus (NIDDM) rats. Fifty-four Sprague-Dawley rats were the subjects of this study. In each rat, NIDDM was induced by an intraperitoneal injection of 90 mg/Kg of streptozotocin on the second day after birth. Based on the diabetic period, they were classified into either short-term or long-term diabetics (avg. 22 weeks, n=18 and avg. 38 weeks, n=20), respectively, and their age-matched controls (n=16). To evaluate the erectile function in each rat, the intracavernous pressure, and latency to maximal pressure, following cavernous nerve stimulation (frequency: 1 Hz, intensity: 3 - 6 V, pulse width: 1 msec, pulse duration: 1 min.) was analyzed. To evaluate both oxidative stress from reactive oxygen species, and antioxidant function as a defense against them, total malondialdehyde and glutathione levels were measured in the corpus cavernosum of the penis, using a spectrophotometric assay. The intracavernous pressure following cavernous nerve stimulation was significantly lower in the long-term (49.8 +/- 9.4 cmH2O) than the short-term diabetics (75.9 +/- 14.8 cm H2O), and markedly decreased in the diabetic rats, compared with their age-matched controls (long-term controls; 60.7 +/- 17.2 cmH2O, short-term controls; 95.2 +/- 20.4 cmH2O). The malondialdehyde content in the corpus cavernosum was markedly increased in the diabetics (2.13 +/- 0.27 nM/mg protein) compared to the controls (1.48 +/- 0.22 nM/mg protein). Furthermore, the glutathione level was significantly decreased in the diabetics, compared to age-matched controls (short-term control; 218.3 +/- 25.6 microM/mg protein, long-term control; 150.2 +/- 9.8 microM/mg protein). In the diabetic groups, it was more significantly decreased in the long-term diabetics (134.8 +/- 11.3 microM/mg protein) than in short-term diabetics (182.1 +/- 18.8 microM/mg protein). NIDDM causes erectile dysfunction, which slowly progresses. Oxidative stress to cavernous tissue may be a contributory factor in erectile dysfunction in diabetics.
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PMID:The role of free radical in the pathogenesis of impotence in streptozotocin-induced diabetic rats. 1272 63

Uncoupling proteins (UCP) are carriers expressed in the mitochondrial inner membrane that uncouple oxygen consumption by the respiratory chain from ATP synthesis. UCP2 is a member of the multigenic UCP family that is expressed in a wide range of tissues and organs. Possible functions of UCP2 include control of ATP synthesis, regulation of fatty acid metabolism and control of reactive oxygen species production. UCP2 expression in tissues involved in lipid and energy metabolism and mapping of the gene to a region linked to obesity and hyperinsulinemia prompted studies on the involvement of UCP2 in metabolic disorders, and especially in type 2 diabetes. In human adipose tissue and skeletal muscle, UCP2 expression is increased during fasting. The carrier was shown to be under the control of fatty acids and thyroid hormones in vivo. An upregulation has been observed in the liver during high-fat feeding and obesity. However, data in UCP2 gene knockout mice do not support a role for UCP2 in steatohepatitis. The most compelling metabolic role of UCP2 comes from studies in pancreatic beta cells. Overexpression in isolated pancreatic islets results in decreased ATP content and blunted glucose-stimulated insulin secretion. UCP2-deficient mice show an increased ATP level and an enhanced insulin secretion. Lack of UCP2 dramatically improves insulin secretion and decreases hyperglycemia in leptin-deficient mice. The role of UCP2 in the control of insulin secretion constitutes, to date, the most pertinent path to investigate in a therapeutic perspective.
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PMID:The role of uncoupling protein 2 in the development of type 2 diabetes. 1274 44

Metformin (dimethylbiguanide) is an antihyperglycemic agent used in type 2 diabetes. Beyond its action on glycemic control, metformin exhibits other intrinsic effects that could play a role in prevention against diabetes complications. Some studies thus reported an improvement in the antioxidant status in patients treated with metformin. This might be in part related to its property to limit formation of advanced glycation end products (AGEs) and to decrease the overproduction of free radicals in diabetic subjects. The aim of this study was to investigate the in vitro ability of metformin to modulate the action of reactive oxygen species (ROS) generated either by water gamma radiolysis or by stimulated human leukocytes. Our results showed that metformin at pharmacologically relevant concentrations was in vitro able to scavenge hydroxyl ((.)OH) but not superoxide (O(.-)(2)) free radicals and that hydrogen peroxide did not react with metformin. Nevertheless, when polymorphonuclear cells (PMN) are stimulated by phorbol myristate acetate (PMA), or above all by formyl methionine leucyl phenylalanine (fMLP), a systematic (although nonsignificant) decrease of the ROS-induced chimiluminescence (CL) was observed. These results suggest that metformin could directly scavenge ROS or indirectly act by modulating the intracellular production of superoxide anion, of which NADPH oxidase constitutes the major source. This could contribute to the additional benefits of metformin, especially those related to the improvement in the cardiovascular outcomes in diabetes.
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PMID:An intracellular modulation of free radical production could contribute to the beneficial effects of metformin towards oxidative stress. 1275 88

Exposure to high concentrations of glucose and insulin results in insulin resistance of metabolic target tissues, a characteristic feature of type 2 diabetes. High glucose has also been associated with oxidative stress, and increased levels of reactive oxygen species have been proposed to cause insulin resistance. To determine whether oxidative stress contributes to insulin resistance induced by hyperglycemia in vivo, nondiabetic rats were infused with glucose for 6 h to maintain a circulating glucose concentration of 15 mM with and without coinfusion of the antioxidant N-acetylcysteine (NAC), followed by a 2-h hyperinsulinemic-euglycemic clamp. High glucose (HG) induced a significant decrease in insulin-stimulated glucose uptake [tracer-determined disappearance rate (Rd), control 41.2 +/- 1.7 vs. HG 32.4 +/- 1.9 mg. kg-1. min-1, P < 0.05], which was prevented by NAC (HG + NAC 45.9 +/- 3.5 mg. kg-1. min-1). Similar results were obtained with the antioxidant taurine. Neither NAC nor taurine alone altered Rd. HG caused a significant (5-fold) increase in soleus muscle protein carbonyl content, a marker of oxidative stress that was blocked by NAC, as well as elevated levels of malondialdehyde and 4-hydroxynonenal, markers of lipid peroxidation, which were reduced by taurine. In contrast to findings after long-term hyperglycemia, there was no membrane translocation of novel isoforms of protein kinase C in skeletal muscle after 6 h. These data support the concept that oxidative stress contributes to the pathogenesis of hyperglycemia-induced insulin resistance.
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PMID:N-acetylcysteine and taurine prevent hyperglycemia-induced insulin resistance in vivo: possible role of oxidative stress. 1279 18

Increasing evidence shows that the overproduction of reactive oxygen species, induced by diabetic hyperglycemia, contributes to the development of several cardiopathologies. The susceptibility of diabetic hearts to oxidative stress, induced in vitro by ADP-Fe2+ in mitochondria, was studied in 12-month-old Goto-Kakizaki rats, a model of non-insulin dependent diabetes mellitus, and normal (non-diabetic) Wistar rats. In terms of lipid peroxidation the oxidative damage was evaluated on heart mitochondria by measuring both the O2 consumption and the concentrations of thiobarbituric acid reactive substances. Diabetic rats display a more intense formation of thiobarbituric acid reactive substances and a higher O2 consumption than non-diabetic rats. The oxidative damage, assessed by electron microscopy, was followed by an extensive effect on the volume of diabetic heart mitochondria, as compared with control heart mitochondria. An increase in the susceptibility of diabetic heart mitochondria to oxidative stress can be explained by reduced levels of endogenous antioxidants, so we proceeded in determining alpha-tocopherol, GSH and coenzyme Q content. Although no difference of alpha-tocopherol levels was found in diabetic rats as compared with control rat mitochondria, a significant reduction in GSH (21.5% reduction in diabetic rats) and coenzyme Q levels of diabetic rats was observed. The data suggest that a significant decrease of coenzyme Q9, a potent antioxidant involved in the elimination of mitochondria-generated reactive oxygen species, may be responsible for an increased susceptibility of diabetic heart mitochondria to oxidative damage.
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PMID:Diabetes and mitochondrial oxidative stress: a study using heart mitochondria from the diabetic Goto-Kakizaki rat. 1284 58

Over the past three decades, we have witnessed an improvement of survival in those patients with the trio of metabolic syndrome, prediabetes, and overt type 2 diabetes mellitus. Revolutionary changes in technology and an improved understanding of the mechanisms involved in acute coronary syndromes have resulted in this observation. Due to advances in coronary care, we are currently at a crossroads, wherein, the mortality from acute cardiovascular events have been declining and the mortality associated with this trio has been increasing due to congestive heart failure (CHF). This intersect between the two causes of death represent a challenge for the future, as the numbers of patients with this deadly trio are undergoing exponential growth not only in the U.S. but also abroad as more countries undergo urbanization and adopt a western-type lifestyle of over nutrition and under exercise. Thus, we live to die another day. There are multiple metabolic toxicities in this toxic trio, which predispose to an increase in reactive oxygen species and resultant redox stress within the vascular intima and myocardium. By aggressively reducing the elevated substrates producing reactive oxygen species we may be able to restore our individual, endogenous, potent, antioxidant (antiredoxidant) network. Appropriately, we need to examine the mechanisms that result in the development and transition from diastolic and systolic dysfunction to the clinical syndrome of overt CHF with its inherent increase in morbidity and mortality.
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PMID:Myocardial redox stress and remodeling in metabolic syndrome, type 2 diabetes mellitus, and congestive heart failure. 1288 68

Rheopheresis is a specific application of membrane differential filtration, synonymous with double filtration plasmapheresis, for extracorporeal hemorheotherapy. Safety and efficacy of Rheopheresis for wound healing and skin oxygenation were investigated in patients with ischemic diabetic foot syndrome. Eight patients with type 2 diabetes mellitus and non-healing foot ulcers caused by severe ischemic diabetic foot syndrome were treated by a series of seven Rheopheresis sessions in a time span of 11 weeks. Wound healing had not been detectable under conditions of standardized wound care during at least 2 months. Wound status was classified by its morphology, severity and location, according to the criteria of Wagner. Transcutaneous oxygen pressure (tcPO2), laser Doppler flowmetry and vital capillary microscopy were repeatedly performed to monitor the effects of the Rheopheresis treatment series on microcirculation and skin blood flow. Laboratory parameters of blood rheology, endothelial function and inflammatory state were measured in addition to safety parameters. In four patients (baseline Wagner stage 2), Rheopheresis accelerated wound healing of foot ulcers and was associated with an improvement of Wagner stage and a pronounced increase in tcPO2. In two patients (baseline Wagner stage 2), wound healing was unchanged but mean tcPO2 increased, allowing successful minor amputation. Values of tcPO2 remained stable and enhanced for the 3 months follow-up period. In two patients (baseline Wagner stage 4 or 5), no improvements in foot lesions were observed within the treatment period. As an adjunct therapeutic option, Rheopheresis may preserve a functional lower extremity, delay amputation or reduce the extent of amputation.
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PMID:Rheopheresis in patients with ischemic diabetic foot syndrome: results of an open label prospective pilot trial. 1288 30

Elevation of plasma glucose concentration may induce generation of oxygen-free radicals, which can play an important role in the progression of diabetes and/or development of its complications. Various glutathione transferases utilize the availability of reduced glutathione for the cellular defense against oxygen-free radicals. One such enzyme is microsomal glutathione S-transferase 3 encoded by MGST3, which maps to chromosome 1q23, a region linked to Type 2 diabetes mellitus (T2DM) in Pima Indians, Caucasian, and Chinese populations. We investigated the MGST3 gene as a potential susceptibility gene for T2DM by screening this locus for single nucleotide polymorphisms (SNPs) in diabetic and non-diabetic Pima Indians. We also measured the skeletal muscle MGST3 mRNA level by Real-Time (RT) PCR and its relationship with insulin action in non-diabetic individuals. We identified 25 diallelic variants, most of which, based on their genotypic concordance, could be divided into three distinct linkage disequilibrium (LD) groups. We genotyped unique representative SNPs in selected diabetic and non-diabetic Pima Indians and found no evidence for association with T2DM. Furthermore, inter-individual variation of skeletal muscle MGST3 mRNA was not correlated with differences in insulin action in non-diabetic subjects. We conclude that alterations of MGST3 are unlikely to contribute to T2DM or differences in insulin sensitivity in the Pima Indians.
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PMID:Evaluation of the microsomal glutathione S-transferase 3 (MGST3) locus on 1q23 as a Type 2 diabetes susceptibility gene in Pima Indians. 1289 15


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