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Query: UMLS:C0011849 (diabetes)
 277,896 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Lipid disorders and increased oxidative stress may exacerbate some complications of diabetes mellitus. Previous studies have implicated the beneficial effects of some antioxidants, omega-3 polyunsaturated fatty acids (PUFAs), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in the protection of cells from the destructive effect of increased lipids and lipid peroxidation products. This study, therefore, was designed to investigate the effects of cod liver oil (CLO, Lysi Ltd. Island), which comprises mainly vitamin A, PUFAs, EPA and DHA. Effects were monitored on plasma lipids, lipid peroxidation products (MDA) and the activities of antioxidant enzymes, glutathione peroxidase (GSHPx) and catalase in heart, liver, kidney and lung of non-diabetic control and streptozotocin (STZ)-induced-diabetic rats. Two days after STZ-injection (55 mg kg(-1) i.p.), non-diabetic control and diabetic rats were divided randomly into two groups as untreated or treated with CLO (0.5 ml kg(-1) rat per day) for 12 weeks. Plasma glucose, triacylglycerol and cholesterol concentrations were significantly elevated in 12-week untreated-diabetic animals; CLO treatment almost completely prevented these abnormalities in triacylglycerol and cholesterol, but hyperglycaemia was partially controlled. CLO also provided better weight gain in diabetic animals. In untreated diabetic rats, MDA markedly increased in aorta, heart and liver but was not significantly changed in kidney and lung. This was accompanied by a significant increase in both GSHPx and catalase enzyme activities in aorta, heart, and liver of diabetic rats. In kidney and lung, diabetes resulted in reduced catalase while GSHPx was significantly activated. In aorta, heart, and liver, diabetes-induced changes in MDA were entirely prevented by CLO treatment. In the tissues of CLO-treated diabetic animals, GSHPx activity paralleled those of control animals. CLO treatment also caused significant improvements in catalase activities in every tissue of diabetic rats, but failed to affect MDA and antioxidant activity in control animals. The current study suggests that the treatment of diabetic rats with CLO provides better control of glucose and lipid metabolism, allows recovery of normal growth rate, prevents oxidative/peroxidative stress and ameliorates endogenous antioxidant enzyme activities in various tissues. Because CLO contains a plethora of beneficial compounds together, its use for the management of diabetes-induced complications may provide important advantages.
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PMID:Effects of cod liver oil on tissue antioxidant pathways in normal and streptozotocin-diabetic rats. 1241 63

Determination of reliable bioindicators of diabetes-induced oxidative stress and the role of dietary vitamin E supplementation were investigated. Blood (plasma) chemistries, lipid peroxidation (LPO), and antioxidant enzyme activities were measured over 12 weeks in New Zealand White rabbits (control, diabetic, and diabetic + vitamin E). Cholesterol and triglyceride levels did not correlate with diabetic state. Plasma LPO was influenced by diabetes and positively correlated with glucose concentration only, not cholesterol or triglycerides. Liver glutathione peroxidase (GPX) activity negatively correlated with glucose and triglyceride levels. Plasma and erythrocyte GPX activities positively correlated with glucose, cholesterol, and triglyceride concentrations. Liver superoxide dismutase activity positively correlated with glucose and cholesterol concentration. Vitamin E reduced plasma LPO, but did not affect the diabetic state. Thus, plasma LPO was the most reliable indicator of diabetes-induced oxidative stress. Antioxidant enzyme activities and types of reactive oxygen species generated were tissue dependent. Diabetes-induced oxidative stress is diminished by vitamin E supplementation.
Int J Exp Diabetes Res
PMID:Differential indicators of diabetes-induced oxidative stress in New Zealand White rabbits: role of dietary vitamin E supplementation. 1245 60

Effects of cobalt on the antioxidant status of control and streptozotocin diabetic rat heart and aorta were examined at the second, fourth and sixth week of treatment. Rats were divided into four groups: control, diabetic, control treated with cobalt chloride and diabetic treated with cobalt chloride. Diabetes was induced by tail vein injection of streptozotocin (STZ). Cobalt treatment groups were given 0.5 mM of CoCl(2) in drinking water. The rats in both groups were further subdivided into three groups of six rats each. Rats in these subgroups were studied at 2-week intervals up to 6 weeks. At the end of the experiment, all animals were sacrificed by decapitation, heart and aorta samples were removed for determination of thiobarbituric acid reactive substance (TBARS) level and superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) activities. It was found that lipid peroxidation levels and antioxidant enzyme activities were increased in the streptozotocin-induced diabetic rats at all times studied. Cobalt treatment of diabetic rats (0.5 mM in drinking water) resulted in attenuation of the increased levels of TBARS and antioxidant enzyme activities in heart and aorta. Thus, the effect of oral administration of cobalt at this dose during the early stage of experimental diabetes can be considered as a consequence of altered endogenous defence mechanisms in heart and aorta.
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PMID:Effect of cobalt on the oxidative status in heart and aorta of streptozotocin-induced diabetic rats. 1257 18

Chronic exposure to hyperglycemia can lead to cellular dysfunction that may become irreversible over time, a process that is termed glucose toxicity. Our perspective about glucose toxicity as it pertains to the pancreatic beta-cell is that the characteristic decreases in insulin synthesis and secretion are caused by decreased insulin gene expression. The responsible metabolic lesion appears to involve a posttranscriptional defect in pancreas duodenum homeobox-1 (PDX-1) mRNA maturation. PDX-1 is a critically important transcription factor for the insulin promoter, is absent in glucotoxic islets, and, when transfected into glucotoxic beta-cells, improves insulin promoter activity. Because reactive oxygen species are produced via oxidative phosphorylation during anaerobic glycolysis, via the Schiff reaction during glycation, via glucose autoxidation, and via hexosamine metabolism under supraphysiological glucose concentrations, we hypothesize that chronic oxidative stress is an important mechanism for glucose toxicity. Support for this hypothesis is found in the observations that high glucose concentrations increase intraislet peroxide levels, that islets contain very low levels of antioxidant enzyme activities, and that adenoviral overexpression of antioxidant enzymes in vitro in islets, as well as exogenous treatment with antioxidants in vivo in animals, protect the islet from the toxic effects of excessive glucose levels. Clinically, consideration of antioxidants as adjunct therapy in type 2 diabetes is warranted because of the many reports of elevated markers of oxidative stress in patients with this disease, which is characterized by imperfect management of glycemia, consequent chronic hyperglycemia, and relentless deterioration of beta-cell function.
Diabetes 2003 Mar
PMID:Glucose toxicity in beta-cells: type 2 diabetes, good radicals gone bad, and the glutathione connection. 1260 96

Insulin-producing cells show very low activity levels of the cytoprotective enzymes catalase, glutathione peroxidase, and superoxide dismutase. This weak antioxidative defense status has been considered a major feature of the poor resistance against oxidative stress. Therefore, we analyzed the protective effect of a combined overexpression of Cu,ZnSOD or MnSOD together with different levels of catalase. Catalase alone was able to increase the resistance of transfected RINm5F insulin-producing tissue culture cells against H(2)O(2) and HX/XO, but no protection was seen in the case of menadione. In combination with an increase of the MnSOD or Cu,ZnSOD expression, the protective action of catalase overexpression could be further increased and extended to the toxicity of menadione. Thus, optimal protection of insulin-producing cells against oxidative stress-mediated toxicity requires a combined overexpression of both superoxide- and hydrogen peroxide-inactivating enzymes. This treatment can compensate for the constitutively low level of antioxidant enzyme expression in insulin-producing cells and may provide an improved protection in situations of free radical-mediated destruction of pancreatic beta cells in the process of autoimmune diabetes development.
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PMID:Sequential inactivation of reactive oxygen species by combined overexpression of SOD isoforms and catalase in insulin-producing cells. 1263 45

Methylglyoxal (MG), a physiological alpha-dicarbonyl compound is derived from glycolytic intermediates and produced during the Maillard reaction. The Maillard reaction, a non-enzymatic reaction of ketones and aldehydes with amino group of proteins, contributes to the aging of proteins and to complications associated with diabetes. In our previous studies (Che, et al. (1997) "Selective induction of heparin-binding epidermal growth factor-like growth factor by MG and 3-deoxyglucosone in rat aortic smooth muscle cells. The involvement of reactive oxygen species formation and a possible implication for atherogenesis in diabetes". J. Biol. Chem., 272, 18453-18459), we reported that MG elevates intracellular peroxide levels, but the mechanisms for this remain unclear. Here, we report that MG inactivates bovine glutathione peroxidase (GPx), a major antioxidant enzyme, in a dose- and time-dependent manner. The use of BIAM labeling, it was showed that the selenocysteine residue in the active site was intact when GPx was incubated with MG. MALDI-TOF-MS (matrix-assisted laser desorption/ionization time-of-flight mass spectrometry) and protein sequencing examined the possibility that MG modifies arginine residues in GPx. The results show that Arg 184 and Arg 185, located in the glutathione binding site of GPx was irreversively modified by treatment with MG. Reactive dicarbonyl compounds such as 3-deoxyglucosone, glyoxal and phenylglyoxal also inactivated GPx, although the rates for this inactivation varied widely. These data suggest that dicarbonyl compounds are able to directly inactivate GPx, resulting in an increase in intracellular peroxides which are responsible for oxidative cellular damage.
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PMID:Identification of the binding site of methylglyoxal on glutathione peroxidase: methylglyoxal inhibits glutathione peroxidase activity via binding to glutathione binding sites Arg 184 and 185. 1265 9

The presence of thioredoxin peroxidase (TPx), also known as thiol specific antioxidant (TSA), was investigated in neonatal and adult rat islets, and in the beta-cell line HIT-T15. Western blotting of extracts from neonatal and adult pancreatic islets and from the tumoral cell line HIT-T15 revealed the presence of a 25 kDa protein that comigrated with purified yeast TPx. Endocrine pancreatic TPx accounted for approximately 0.01% of the total protein content. Treatment with H2O2 for 3 h increased the expression of TPx in HIT-T15 cells. The distribution of TPx throughout the islet cells was confirmed by immunocytochemistry. Since pancreatic beta-cells possess a weak antioxidant enzyme defense system, especially with regard to hydrogen peroxidase-decomposing enzymes, the presence of a TPx analog in islets suggests that this enzyme may play a role in protecting pancreatic cells against reactive oxygen species.
Diabetes Metab 2002 Dec
PMID:Expression of a thioredoxin peroxidase in insulin-producing cells. 1268 30

Effects of cytotoxic agents and hydrogen peroxide were examined using pancreatic BRIN-BD11 cells and the parental insulinoma RINm5F cell line. Cell viability was determined using the MTT colorimetric assay and the TUNEL assay was used to assess apoptosis and acridine orange assay was used to determine levels of apoptosis versus necrosis. RT-PCR studies were employed to investigate the effects of the toxins on the expression of antioxidative enzymes, superoxide dismutase (SOD), glutathionine peroxidase (GPX) and catalase (CAT). Streptozotocin, hydrogen peroxide, alloxan and ninhydrin exerted time- and concentration-dependent toxic effects on BRIN-BD11 and RINm5F cells. RT-PCR showed that 90 minutes exposure of BRIN-BD11 cells or RINm5F cells to 5 mM ninhydrin down regulates SOD, GPX and CAT antioxidative enzymes. Glutathionine peroxidase gene expression was also down regulated in both types of cell by hydrogen peroxide. There were no significant differences in antioxidant gene expression after exposure to the other toxins under the conditions employed. TUNEL assay revealed that streptozotocin (8 mM) and hydrogen peroxide (125 microM) had no significant effect on the number of cells undergoing apoptosis. However after exposure to ninhydrin (5 mM) almost 100% of the non-viable BRIN-BD11 cells and around 50% of the RINm5F cells were dying by apoptosis. With the BRIN-BD11 cells there was around a 30% increase in the number of apoptotic cells compared with 50% in the RINm5F cells after exposure to alloxan (16 mM). The results indicate multiple effects of cytotoxic agents on functional integrity and antioxidant enzyme gene expression in clonal beta-cells.
Diabetes Metab 2002 Dec
PMID:Effects of cytotoxic agents on functional integrity and antioxidant enzymes in clonal beta-cells. 1268 36

The effect of sulfur dioxide (SO2) on brain antioxidant status, lipid peroxidation, and somatosensory evoked potentials (SEPs) was investigated in diabetic rats. A total of 40 rats were divided into 4 equal groups: control (C), SO2 + C (SO2), diabetic (D), and SO2 + D (DSO2). Experimental diabetes mellitus was induced by i.v. injection of alloxan at a dose of 50 mg/kg body weight. Ten ppm SO2 was administered to the rats in the sulfur dioxide groups (SO2 and DSO2) in an exposure chamber. Exposure occurred 1 hr/day, 7 days/wk, for 6 wk; control rats were exposed to filtered air during the same time periods. Although SO2 exposure markedly increased copper, zinc Superoxide dismutase activity, it significantly decreased glutathione peroxidase activity in both the diabetic and nondiabetic groups, compared with the C group. Brain catalase activity was unaltered; however, brain thiobarbituric acid reactive substances (TBARS) were elevated in all experimental groups with respect to the C group. SEP components P1, N1, P2, and N2 were significantly increased in all experimental groups, compared with the C group, and these components were also prolonged in the DSO2 group with respect to the other groups. The authors' findings suggest that exposure to SO2, because it increases lipid peroxidation, can change antioxidant enzyme activities and affect SEP components in diabetic rats.
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PMID:Changes in somatosensory evoked potentials, lipid peroxidation, and antioxidant enzymes in experimental diabetes: effect of sulfur dioxide. 1274 14

Oxidative stress is implicated in the pathophysiology of a number of chronic diseases including atherosclerosis, diabetes, cataracts and accelerated aging. The aim of this study was to elucidate the protective role of vitamin E supplementation when oxidative stress is induced by CCl4 administration, using the rat as a model. Rats were fed diets for four weeks either with or without dl-alpha-tocopherol acetate supplementation. Half of the rats (n = 9) from each of the diet groups were then challenged with CCl4 at the completion of the four week diet period. Plasma levels of 8-iso-PGF(2alpha), antioxidant micronutrients and antioxidant enzyme activities were measured to examine changes in oxidative stress subsequent to the supplementation of dl-alpha-tocopherol in the diet. Plasma alpha-tocopherol (vitamin E) concentrations were higher for the groups supplemented with dl-alpha-tocopherol acetate, however the supplemented diet group that was subsequently challenged with CCl4 had significantly lower (p <0.001) plasma alpha-tocopherol concentration than the dl-alpha-tocopherol acetate diet group that was not challenged with CCl4. Total plasma 8-iso-PGF(2alpha) concentration was elevated in diet groups challenged with CCl4, however, the concentration was significantly lower (p <0.001) when the diet was supplemented with dl-alpha-tocopherol acetate. The antioxidant enzymes were not influenced by either dietary alpha-tocopherol manipulation or by the inducement of oxidative stress with CCl4. Plasma concentrations of trans-retinol (vitamin A) were reduced by CCl4 administration in both the dl-alpha-tocopherol acetate supplemented and unsupplemented diet groups. The results of this study indicate that dl-alpha-tocopherol acetate supplementation was protective of lipid peroxidation when oxidative stress is induced by a pro-oxidant challenge such as CCl4.
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PMID:Vitamin E supplementation in the mitigation of carbon tetrachloride induced oxidative stress in rats. 1277 Jun 45


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