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Query: UMLS:C0011860 (type 2 diabetes)
 57,723 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The prevalence of peripheral vascular disease (PVD) in diabetic patients is manyfold higher than that of age- and sex-matched nondiabetic subjects. This study was designed to evaluate the relationship between quantitatively determined peripheral circulation in the lower extremities and arterial wall thickness or stiffness in 68 patients with type 2 diabetes. Peripheral circulation during treadmill-exercise was monitored by transcutaneous oxygen tension (TcPO2) and was expressed as percentage of post-exercise TcPO2 adjusted by that of pre-exercise (TcPO2 index). Arterial wall thickness (intima-media thickness; IMT) and stiffness (stiffness beta) were measured by ultrasonography. TcPO2 index was negatively (r=-0.350, P=0.0007) correlated with stiffness beta, not with IMT, of the femoral artery. In patients without insulin therapy (n=52), both fasting plasma insulin concentration (r=-0.323, P=0.0023) and HOMA IR, an insulin resistance index, (r=-0.281, P=0.0084) were negatively correlated with TcPO2 index. Multiple regression analyses showed that association of stiffness beta of the femoral artery or HOMA IR with the TcPO2 index was independent of other factors including age, smoking index, ankle brachial pressure index and IMT of femoral artery. Thus, arterial wall stiffness of femoral artery appears to be a major determinant of peripheral circulation in patients with type 2 diabetes.
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PMID:Arterial wall stiffness is associated with peripheral circulation in patients with type 2 diabetes. 1295 86

To explore the mechanisms for the insulin resistance associated with a family history of type 2 diabetes, we studied 16 healthy men with at least two first-degree relatives with type 2 diabetes and 16 control subjects without known heredity. They were pair-wise matched for age, body mass index, and fasting triglycerides and underwent an oral glucose tolerance test, iv glucose infusion to measure the early insulin secretion, euglycemic hyperinsulinemic clamp, computed tomography scan, 7-d food record, and a cardiopulmonary exercise test to measure peak oxygen uptake. Insulin sensitivity index was 30% lower (P = 0.02) in relatives, compared with controls, but fasting and 2-h blood glucose and first-phase insulin secretion were similar. There were no differences in mean fasting free fatty acid levels, amount of sc or visceral adipose tissue, or fat accumulation in the liver. Dietary intake and peak oxygen uptake were also similar. However, multiple regression analysis of both groups showed that fat in the liver and physical capacity were, like known heredity for type 2 diabetes, independent predictors of insulin sensitivity. Thus, lipid accumulation in the liver and physical capacity are related to insulin sensitivity, but neither of these factors nor the amount and distribution of the body fat can explain the insulin resistance associated with a family history for type 2 diabetes.
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PMID:Fat distribution, lipid accumulation in the liver, and exercise capacity do not explain the insulin resistance in healthy males with a family history for type 2 diabetes. 1297 Feb 92

Several links relate mitochondrial metabolism and type 2 diabetes or chronic hyperglycaemia. Among them, ATP synthesis by oxidative phosphorylation and cellular energy metabolism (ATP/ADP ratio), redox status and reactive oxygen species (ROS) production, membrane potential and substrate transport across the mitochondrial membrane are involved at various steps of the very complex network of glucose metabolism. Recently, the following findings (1) mitochondrial ROS production is central in the signalling pathway of harmful effects of hyperglycaemia, (2) AMPK activation is a major regulator of both glucose and lipid metabolism connected with cellular energy status, (3) hyperglycaemia by inhibiting glucose-6-phosphate dehydrogenase (G6PDH) by a cAMP mechanism plays a crucial role in NADPH/NADP ratio and thus in the pro-oxidant/anti-oxidant cellular status, have deeply changed our view of diabetes and related complications. It has been reported that metformin has many different cellular effects according to the experimental models and/or conditions. However, recent important findings may explain its unique efficacy in the treatment of hyperglycaemia- or insulin-resistance related complications. Metformin is a mild inhibitor of respiratory chain complex 1; it activates AMPK in several models, apparently independently of changes in the AMP-to-ATP ratio; it activates G6PDH in a model of high-fat related insulin resistance; and it has antioxidant properties by a mechanism (s), which is (are) not completely elucidated as yet. Although it is clear that metformin has non-mitochondrial effects, since it affects erythrocyte metabolism, the mitochondrial effects of metformin are probably crucial in explaining the various properties of this drug.
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PMID:Mitochondrial metabolism and type-2 diabetes: a specific target of metformin. 1450 5

Intrauterine growth retardation (IUGR) has been linked to the development of type 2 diabetes in adulthood. We have developed an IUGR model in the rat whereby the animals develop diabetes between 3 and 6 mo of age that is associated with insulin resistance. Alterations in hepatic glucose metabolism are known to contribute to the hyperglycemia of diabetes; however, the mechanisms underlying this phenomenon have not been fully explained. To address this issue, intact liver mitochondria were isolated from IUGR and control offspring at different ages to examine the nature and time course of possible defects in oxidative metabolism. Phosphoenolpyruvate carboxykinase (PEPCK) expression was also measured in livers of IUGR and control offspring. Rates of ADP-stimulated (state 3) oxygen consumption were increased for succinate in the fetus and for alpha-ketoglutarate and glutamate at day 1, reflecting possible compensatory metabolic adaptations to acute hypoxia and acidosis in IUGR rats. By day 14, oxidation of glutamate and alpha-ketoglutarate had returned to normal, and by day 28, oxidation rates of pyruvate, glutamate, succinate, and alpha-ketoglutarate were significantly lower than those of controls. Rotenone-sensitive NADH-O2 oxidoreductase activity was similar in control and IUGR mitochondria at all ages, showing that the defect responsible for decreased pyruvate, glutamate, and alpha-ketoglutarate oxidation in IUGR liver precedes the electron transport chain and involves pyruvate and alpha-ketoglutarate dehydrogenases. Increased levels of manganese superoxide dismutase suggest that an antioxidant response has been mounted, and hydroxynonenal (HNE) modification of pyruvate dehydrogenase E2-(catalytic) and E3-binding protein subunits suggests that HNE-induced inactivation of this key enzyme may play a role in the mechanism of injury. The level of PEPCK mRNA was increased 250% in day 28 IUGR liver, indicating altered gene expression of the gluconeogenic enzyme that precedes overt hyperglycemia. These results indicate that uteroplacental insufficiency impairs mitochondrial oxidative phosphorylation in the liver and that this derangement predisposes the IUGR rat to increased hepatic glucose production by suppressing pyruvate oxidation and increasing gluconeogenesis.
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PMID:Impaired oxidative phosphorylation in hepatic mitochondria in growth-retarded rats. 1460 83

Carbonyl stress is one of the important mechanisms of tissue damage in vascular complications of diabetes. In the present study, we observed that the plasminogen activator inhibitor-1 (PAI-1) levels in serum and its gene expression in adipose tissue were up-regulated in aged OLETF rats, model animals of obese type 2 diabetes. To study the mechanism of PAI-1 up-regulation, we examined the effect of advanced glycation end products (AGEs) and the product of lipid peroxidation (4-hydroxy-2-nonenal (HNE)), both of which are endogenously generated under carbonyl stress. Stimulation of primary white adipocytes by either AGE or HNE resulted in the elevation of PAI-1 in culture medium and at mRNA levels. The up-regulation of PAI-1 was also observed by incubating the cells in high glucose medium (30 mm, 48 h). The stimulatory effects by AGE or high glucose were inhibited by antioxidant, pyrrolidine dithiocarbamate, and reactive oxygen scavenger, probucol, suggesting a pivotal role of oxidative stress in white adipocytes. We also found that the effect by HNE was inhibited by antioxidant, N-acetylcysteine and that a specific inhibitor of glutathione biosynthesis, l-buthionine-S,R-sulfoximine, augmented the effect of subthreshold effect of HNE. Bioimaging of reactive oxygen species (ROS) by a fluorescent indicator, 6-carboxy-2',7'-dichlorodihydrofluorescein diacetate, revealed ROS production in white adipocytes treated with AGE or HNE. These results suggest that cellular carbonyl stress induced by AGEs or HNE may stimulate PAI-1 synthesis in and release from adipose tissues through ROS formation.
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PMID:Cellular carbonyl stress enhances the expression of plasminogen activator inhibitor-1 in rat white adipocytes via reactive oxygen species-dependent pathway. 1461 81

Glycosylation end-products formed during diabetes mellitus promoted atherogenic oxidative modification of low-density lipoproteins. We evaluated the effects of compensation of carbohydrate metabolism and therapy with antioxidant probucol on parameters of free radical oxidation in patients with type II diabetes mellitus. Compensation of carbohydrate metabolism reduced manifestations of oxidative stress, which was manifested in accelerated enzymatic utilization of reactive oxygen species and lipid peroxides and decreased content of free radical oxidation products in low-density lipoproteins. In patients with type II diabetes mellitus combination therapy with antioxidant probucol decreased the severity of oxidative stress and stabilized carbohydrate metabolism without increasing the dose of hypoglycemic preparations.
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PMID:Interrelation between compensation of carbohydrate metabolism and severity of manifestations of oxidative stress in type II diabetes mellitus. 1463 91

Phosphatidylinositol 3-kinase signaling regulates the expression of several genes involved in lipid and glucose homeostasis; deregulation of these genes may contribute to insulin resistance and progression toward type 2 diabetes. By employing RNA arbitrarily primed-PCR to search for novel phosphatidylinositol 3-kinase-regulated genes in response to insulin in isolated rat adipocytes, we identified fatty aldehyde dehydrogenase (FALDH), a key component of the detoxification pathway of aldehydes arising from lipid peroxidation events. Among these latter events are oxidative stresses associated with insulin resistance and diabetes. Upon insulin injection, FALDH mRNA expression increased in rat liver and white adipose tissue and was impaired in two models of insulin-resistant mice, db/db and high fat diet mice. FALDH mRNA levels were 4-fold decreased in streptozotocin-treated rats, suggesting that FALDH deregulation occurs both in hyperinsulinemic insulin-resistant state and hypoinsulinemic type 1 diabetes models. Moreover, insulin treatment increases FALDH activity in hepatocytes, and expression of FALDH was augmented during adipocyte differentiation. Considering the detoxifying role of FALDH, its deregulation in insulin-resistant and type 1 diabetic models may contribute to the lipid-derived oxidative stress. To assess the role of FALDH in the detoxification of oxidized lipid species, we evaluated the production of reactive oxygen species in normal versus FALDH-overexpressing adipocytes. Ectopic expression of FALDH significantly decreased reactive oxygen species production in cells treated by 4-hydroxynonenal, the major lipid peroxidation product, suggesting that FALDH protects against oxidative stress associated with lipid peroxidation. Taken together, our observations illustrate the importance of FALDH in insulin action and its deregulation in states associated with altered insulin signaling.
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PMID:Fatty aldehyde dehydrogenase: potential role in oxidative stress protection and regulation of its gene expression by insulin. 1463 78

The endothelium is the first line of defense for maintaining normal vascular function in the vessel wall; however, the endothelium is sensitive to metabolic stress. In patients with insulin resistance or type 2 diabetes mellitus, a set of metabolic insults--namely high plasma levels of glucose and free fatty acids, increased inflammation, dyslipidemia, and hypertension--cause endothelial dysfunction and a transition from an antiatherogenic endothelium to a proatherogenic endothelium. Disruption of endothelial function leads to activation of platelets and macrophages, increased thrombotic potential, transition of macrophages to foam cells, stimulation of cytokine secretion, and proliferation of vascular smooth muscle cells. Insulin-sensitizing agents, such as the thiazolidinediones (TZDs), improve flow-mediated vasodilation, decrease macrophage and smooth muscle cell activation, proliferation, and migration, and decrease plaque formation. The TZDs exert multifaceted effects on the vasculature by regulating the expression of transcription factors and orchestrating whole-gene programs that restore vascular physiology to the healthy state. Exercise training and increased levels of habitual physical activity have therapeutic benefit in terms of both preventing and treating insulin resistance and diabetes. However, this benefit of exercise training and increased physical activity is complicated by the fact that individuals with insulin resistance or type 2 diabetes have decreased maximal exercise capacity or maximal oxygen consumption and have slower oxygen uptake kinetics at the beginning of exercise. Both of these abnormalities contribute to the decreased levels of habitual physical activity observed in patients with diabetes. Preliminary data suggest that TZDs improve measures of cardiac function and exercise capacity, and investigators are assessing the impact of treatment with rosiglitazone on exercise capacity in an ongoing clinical trial.
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PMID:Novel actions of thiazolidinediones on vascular function and exercise capacity. 1467 69

Obesity is accompanied by a high incidence of atherosclerosis, arterial hypertension and non-insulin dependent diabetes mellitus in the pathogenesis of which is associated with oxygen-derived free radicals. The aim of the study was to compare blood oxidation status in obese women without coexisting diseases and in healthy women with normal body mass index (BMI). Studies were performed in 29 premenopausal obese (BMI 35.79 +/- 4.62 kg/m2) and 31 lean (BMI 22.29 +/- 1.05 kg/m2) women. Plasma lipid profile, activities of antioxidant enzymes: copper/zinc (Cu/ZnSOD) and manganese-containing superoxide dismutase (MnSOD) and glutathione peroxidase (GSH-Px), as well as concentrations of malondialdehyde (MDA)--a product of lipid peroxidation, were examined. In obese women there were significantly higher concentrations of total cholesterol (5.02 +/- 0.83 vs. 4.15 +/- 0.43 mmol/l; p < 0.05), LDL-cholesterol (3.12 +/- 0.90 vs. 2.35 +/- 0.42 mmol/l; p < 0.05) and triglycerides (1.72 +/- 0.85 vs. 1.02 +/- 0.18 mmol/l; p < 0.01), while HDL-cholesterol level was lower (1.01 +/- 0.16 vs. 1.25 +/- 0.2 mmol/l; p < 0.05). Moreover, in comparison to the control group, obese women showed increased activities of plasma MnSOD (6.72 +/- 1.43 vs. 4.99 +/- 0.58 NU/ml; p < 0.05) and erythrocyte GSH-Px (35.38 +/- 10.31 vs. 19.15 +/- 7.12 mumol NADPH2/g Hb/min; p < 0.001), and concentrations of plasma MDA (2.93 +/- 0.53 vs. 2.16 +/- 0.31 mumol/l; p < 0.05) and erythrocyte MDA (2.24 +/- 0.30 vs. 1.59 +/- 0.36 mumol/g Hb; p < < 0.001). There were no differences between the two groups in activities of plasma and erythrocyte Cu/ZnSOD. In conclusion, the results demonstrate disturbances in oxidation status in premenopausal obese women with abnormal lipid profile, which may indicate the association between oxygen-derived free radicals and the increase in the incidence of obesity-related diseases.
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PMID:[Assessment of blood superoxide dismutase, glutathione peroxidase activity and malondialdehyde concentration as oxidation status parameters in obese women]. 1468 7

Hyperglycemia causes many of the pathological consequences of both type 1 and type 2 diabetes. Much of this damage is suggested to be a consequence of elevated production of reactive oxygen species by the mitochondrial respiratory chain during hyperglycemia. Mitochondrial radical production associated with hyperglycemia will also disrupt glucose-stimulated insulin secretion by pancreatic beta-cells, because pancreatic beta-cells are particularly susceptible to oxidative damage. Therefore, mitochondrial radical production in response to hyperglycemia contributes to both the progression and pathological complications of diabetes. Consequently, strategies to decrease mitochondrial radical production and oxidative damage may have therapeutic potential. This could be achieved by the use of antioxidants or by decreasing the mitochondrial membrane potential. Here, we outline the background to these strategies and discuss how antioxidants targeted to mitochondria, or selective mitochondrial uncoupling, may be potential therapies for diabetes.
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PMID:Prevention of mitochondrial oxidative damage as a therapeutic strategy in diabetes. 1474 75


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