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Query: UMLS:C0011881 (diabetic nephropathy)
 10,836 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

There is direct evidence that there is an increase of concentration of oxidizing species and oxidized products in plasma of human diabetics. The extent of this increase seems to reflect a predilection to diabetic damage. 1. A high concentration of lipid hydroperoxide in plasma was observed in diabetic patients and it's levels correlated well with the degree of diabetic nephropathy. 2. Lipid peroxide causes membrane injury of endothelial cells. The addition of anti-oxidant inhibited cell injury markedly. 3. Malondialdehyde and protein (lysin-residual or low density lipoprotein) made conjugates to change the antigenicity. This results shows the possibility that atherosclerosis as diabetic complication may be caused by immunological reactions with modified proteins for example, oxidized LDL and so on. 4. SOD activity in erythrocytes of diabetic patient was extremely decreased compared with non diabetics, but no difference was observed by the ELISA method with monoclonal antibody. Glycosylation had been expected to occur in various kinds of proteins. The inactivation of SOD may be caused by non enzymatic glycosylation, because negative correlation was observed between the activity of SOD and GHb in erythrocytes. This inactivation of SOD may play an important role in the pathogenesis of diabetic complications. From these results, it was suggested that both free radical reactions and non enzymatic glycosylation may play important roles not only in the development of diabetes but also in its complications.
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PMID:[Free radicals and diabetes mellitus]. 220 Sep 13

Two groups of patients with insulin-dependent diabetes mellitus of > 10 years duration and either persistent normoalbuminuria (group 1, n = 49; albumin excretion < 30 mg/day) or microalbuminuria (group 2, n = 33; albumin excretion 30-300 mg/day) were investigated for evidence of free oxygen radical activity (erythrocytic superoxide dismutase and glutathione peroxidase) and oxidant injury (serum malondialdehyde). Glomerular proteinuria (albuminuria, transferrinuria), tubular proteinuria (retinol-binding protein) and tubular enzymuria (N-acetyl-glucosaminidase and leucine aminopeptidase) were also measured. Healthy controls (n = 38) were matched for age and sex. Groups 1 and 2 were similar in terms of age, sex, duration of diabetes and recent glycaemic control. Serum cholesterol and creatinine were similar in all three groups. Free-radical activity and oxidant injury were significantly higher in groups 1 and 2 than in controls (p < 0.001). Glomerular proteinuria, tubular proteinuria and enzymuria were significantly higher in group 2 than in group 1 and controls (p < 0.01). Group 1 had significantly higher transferrinuria, tubular enzymuria and tubular proteinuria than controls. However, groups 1 and 2 were similar in degree of free oxygen radical generation and oxidant injury. In diabetic nephropathy, oxidant injury and renal tubular damage accompany and may even precede microalbuminuria. The presence of these abnormalities in the absence of glomerular proteinuria favours the hypothesis that alterations first occur in the peritubular microcirculation, which by causing oxidant injury and tubular damage, may initiate diabetic nephropathy.
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PMID:Evidence of oxidant injury and tubular damage in early diabetic nephropathy. 798 55

1. Diabetic nephropathy is a serious microvascular complication in patients with insulin-dependent diabetes mellitus, resulting in end-stage renal disease in 30-45% of such patients. Despite intensive investigation, the pathophysiology of diabetic renal disease has not been fully elucidated. However, several clinical and experimental studies have suggested that endothelial dysfunction and free-radical activity may be important factors. 2. Forty normotensive patients with insulin-dependent diabetes mellitus of between 10 and 20 years duration with persistent normoalbuminuria (albumin excretion < 30 mg/day) and normal renal function were investigated for markers of endothelial dysfunction (plasma von Willebrand factor, soluble thrombomodulin and angiotensin-converting enzyme activity), free oxygen radical generation (erythrocytic superoxide dismutase and glutathione peroxidase) and oxidant injury (serum malondialdehyde). Glomerular proteinuria (albuminuria, transferrinuria), tubular proteinuria (retinol-binding protein) and tubular enzymuria (N-acetyl glucosaminidase and leucine aminopeptidase) were also measured. 3. Patients were divided into two groups. Group 1 comprised 21 patients with elevated markers of endothelial dysfunction, and group 2 comprised 19 patients with normal levels of plasma von Willebrand factor, soluble thrombomodulin and angiotensin-converting enzyme activity. Thirty-eight healthy subjects matched for age and sex acted as controls. 4. Groups 1 and 2 were similar in age, sex, body weight, duration of diabetes mellitus and recent glycaemic control. Serum cholesterol, serum creatinine and glomerular proteinuria were similar in the three groups. Group 1 patients had significantly increased oxidant injury, tubular enzymuria and proteinuria compared with group 2 patients and control subjects (P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Relationship between markers of endothelial dysfunction, oxidant injury and tubular damage in patients with insulin-dependent diabetes mellitus. 828 43

Oxygen free radicals (OFRs) have been suggested to be a contributory factor in complications of diabetes mellitus. In the present study, we investigated the lipid peroxide level measured as thiobarbituric acid reactive substances (TBARS) and activities of antioxidant enzymes viz., [superoxide dismutase (SOD), catalase (CAT) and glutathione-peroxidase (GSH-Px)] in the kidney of streptozotocin induced diabetic rats at various stages of development of diabetes. Sprague Dawley rats were divided into two groups: group I, control (n = 42) and group II, diabetic (n = 42). Each group was further subdivided into seven groups each consisting of six rats. Rats in subgroups were studied at weekly intervals (0 to 6 weeks). Blood glucose levels were estimated at the time of sacrifice. TBARS levels and activity of antioxidant enzymes were measured in kidney. The levels of TBARS in the diabetic group increased initially, dropped to baseline level after 2 weeks and then progressively increased at 5th and 6th week (p < 0.05). There was an increase in catalase activity at first week after that it decreased as compared to control group. However, GSH-Px activity in the diabetic group increased after 1 week and then remained at the same level except a small drop in the 2nd week. Total SOD and CuZn-SOD activity increased significantly in diabetic kidney as compared to controls at all time intervals, while Mn-SOD activity showed no change. The present findings suggest that oxidative stress accompanies at early onset of diabetes mellitus and the susceptibility of the kidney to oxidative stress during the early stages may be an important factor in the development of diabetic nephropathy.
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PMID:Antioxidant defense system in diabetic kidney: a time course study. 904 69

Hyperglycemia directly contributes to the development of diabetic nephropathy. A high-serum glucose concentration alters intraglomerular hemodynamics and promotes deposition of extracellular matrix in the kidney. Nitric oxide (NO) is a short-lived messenger molecule that participates in the regulation of renal blood flow, GFR, and mesangial matrix accumulation. Therefore, in this study it was tested whether high glucose directly modulates NO synthesis by rat mesangial cells in vitro by measuring the accumulation of nitrite, the stable metabolite of NO, in the incubation media. Raising the external glucose concentration to 33.3 mM for 24 to 72 h reduced nitrite levels in cell supernatants in a time-dependent manner to a nadir of 14 +/- 3% of the amount in normal glucose media (5.6 mM) (P < 0.01). The decline in NO synthesis in high glucose media was paralleled by decreased cyclic guanosine monophosphate generation; however, there was no alteration in rat mesangial cell expression of inducible NO synthase protein. The suppressive effect of high glucose on NO production by mesangial cells was not modified by inhibition of protein kinase C (H-7), the addition of antioxidants (vitamin E or superoxide dismutase), or a pan-specific anti-transforming growth factor-beta antibody. An elevated ambient glucose caused a time-dependent reduction in mesangial cell L-arginine content. Addition of L-arginine (10 to 20 mM) to external media partially reversed the inhibitory effect of high glucose on mesangial cell NO production in a dose-dependent manner. The highest dose of L-arginine (20 mM) increased mesangial cell L-arginine content to comparable levels in normal and high glucose media. These results indicate that high glucose causes depletion of L-arginine in mesangial cells and compromises NO synthesis. Limitation in the metabolic precursor and other, as yet unidentified, factors act to reduce NO production by mesangial cells in the presence of an elevated ambient glucose level, a change that may play a role in the development of diabetic glomerulosclerosis.
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PMID:High glucose inhibits nitric oxide production in cultured rat mesangial cells. 925 54

Oxidative stress has been proposed as a possible pathogenic factor for diabetic complications. It is relevant in determining cell replicative capacity and life span, and in vitro antioxidant treatment is able to reverse the impaired proliferative activity of different cell types. It was recently demonstrated that cultured skin fibroblasts from insulin-dependent diabetic patients with nephropathy age prematurely and have a shorter life cell cycle. To test whether the growth phenotype of cells from patients with diabetic nephropathy was related to a lack of protection from oxidative stress, the effect of reduced glutathione (GSH) on cultured skin fibroblasts from 13 insulin-dependent diabetes mellitus (IDDM) patients with nephropathy (DN), 10 IDDM patients without kidney disease (D), and 10 nondiabetic control subjects (C), in normal (5 mM) glucose (NG) and high (22 mM) glucose (HG) medium was studied. After 6 to 8 passages, fibroblasts from DN showed impaired growth both in NG (mean +/- SD fold increase over baseline counts in DN 1.17 +/- 0.6 versus D 1.7 +/- 0.5 versus C 1.95 +/- 0.8; P = 0.04 by ANOVA) and in HG (mean +/- SD fold increase over baseline counts DN 1.16 +/- 0.41 versus D 1.89 +/- 0.66 versus C 2.24 +/- 0.9; P = 0.003 by ANOVA). GSH prevented the growth abnormalities of cells from DN restoring it to values similar to that of the other two groups (mean +/- SD fold increase over baseline counts NG +/- GSH: DN 1.68 +/- 0.9 versus D 1.78 +/- 0.49 versus C 1.99 +/- 0.7, P = 0.6; and in HG + GSH: DN 1.66 +/- 0.69 versus D 1.87 +/- 0.75 versus C 2.2 +/- 0.9, P = 0.3). Growth rates were not affected by the addition of GSH in fibroblasts from D and C. The treatment of fibroblasts from D and C with the inhibitor of the gamma-glutamylcysteine synthetase activity, L-buthionine-S,R-sulfoximine, resulted in growth impairment, and the addition to the culture medium of another antioxidant, superoxide dismutase, corrected the growth abnormalities in fibroblasts from DN. The impaired growth of cultured fibroblasts from IDDM patients with nephropathy is prevented by GSH and superoxide dismutase and is independent of prevailing glucose concentrations. This suggests that oxidative stress is an important mechanism of intrinsic cell dysfunction in these patients.
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PMID:Glutathione reverses the growth abnormalities of skin fibroblasts from insulin-dependent diabetic patients with nephropathy. 962 Dec 89

The aim of this study was to analyse the effect of angiotensin convertase inhibitor, enalapril (ENA), and angiotensin AT-1 receptor antagonist, losartan potassium (LP), on lipid peroxidation and activities of Cu,Zn-superoxide dismutase, catalase and glutathione peroxidase in kidneys of streptozotocin (STZ)-induced diabetic rats after 6 and 12 weeks of treatment. STZ-induced body weight changes and blood glucose concentration were not affected by either ENA or LP but both drugs significantly decreased cholesterol and triglyceride concentrations elevated in diabetic rats, inhibited kidney weight gain, and decreased albuminuria. Kidneys of STZ-diabetic rats had increased malondialdehyde content and decreased activities of antioxidant enzymes (Cu,Zn-superoxide dismutase, catalase and glutathione peroxidase). Both ENA and LP decreased lipid peroxidation and augmented the activities of antioxidant enzymes studied in the kidneys of diabetic rats. These results confirm the role of oxidative stress in the development of diabetic nephropathy already at early stages of the development of diabetes and point to the possible antioxidative mechanism of the nephroprotective action of ENA and LP.
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PMID:Effect of angiotensin convertase inhibitors and AT1 angiotensin receptor antagonists on the development of oxidative stress in the kidney of diabetic rats. 1050 93

Both reactive oxygen species (ROS) and endothelin-1 (ET- 1) have been implicated in the pathophysiology of diabetic nephropathy. The interrelationship between them, however, has not been documented in this disease. To determine whether ROS regulates ET-1 production in diabetic kidneys, we examined the in vitro and in vivo effects of ROS donors and scavengers on ET-1 production of diabetic rat glomeruli. For in vitro study, the glomeruli were isolated with a sieving method from streptozotocin-induced diabetic rats and killed at 1 week, 1 month, and 3 months, respectively. Superoxide was measured by a spectrophotometer, and ET-1 was measured by radioimmunoassay. The results demonstrated that the basal production levels of superoxide and ET-1 were higher in diabetic glomeruli than in normal glomeruli in vitro. There was a positive correlation between the production of superoxide and ET-1 in diabetic glomeruli. The basal ET-1 production was markedly attenuated by ROS scavengers including superoxide dismutase, catalase, dimethyl sulfoxide, and deferoxamine in diabetic glomeruli. Exogenous ROS generated by xanthine/xanthine oxidase significantly enhanced ET-1 generation by both diabetic and normal glomeruli. A high glucose concentration (500 mg/dL) in vitro increased ET-1 production by normal glomeruli but not diabetic glomeruli, and insulin partly suppressed ET- 1 production by diabetic glomeruli. The in vivo study demonstrated that when diabetic rats were injected daily with superoxide dismutase or catalase after diabetes was induced, the basal production of ET-1 was markedly attenuated after 1 week and 1 month, respectively. These results indicate that exogenously or endogenously derived ROS can enhance ET-1 production by diabetic rat glomeruli and that ROS scavengers suppress ET- 1 production both in vitro and in vivo. The effects of ROS on ET-1 production of diabetic glomeruli may be partly caused by the effect of hyperglycemia or insulin deficiency.
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PMID:Reactive oxygen species enhances endothelin-1 production of diabetic rat glomeruli in vitro and in vivo. 1077 44

The development and progression of diabetic nephropathy is dependent on glucose homeostasis and many other contributing factors. In the present study, we examined the effect of nitecapone, an inhibitor of the dopamine-metabolizing enzyme catechol-O-methyl transferase (COMT) and a potent antioxidant, on functional and cellular determinants of renal function in rats with streptozotocin-induced diabetes. Administration of nitecapone to diabetic rats normalized urinary sodium excretion in a manner consistent with the dopamine-dependent inhibition of proximal tubule Na,K-ATPase activity. Hyperfiltration, focal glomerulosclerosis, and albuminuria were also reversed by nitecapone, but in a manner that is more readily attributed to the antioxidant potential of the agent. A pattern of elevated oxidative stress, measured as CuZn superoxide dismutase gene expression and thiobarbituric acid-reactive substance content, was noted in diabetic rats, and both parameters were normalized by nitecapone treatment. In diabetic rats, activation of glomerular protein kinase C (PKC) was confirmed by isoform-specific translocation and Ser23 phosphorylation of the PKC substrate Na,K-ATPase. PKC-dependent changes in Na,K-ATPase phosphorylation were associated with decreased glomerular Na,K-ATPase activity. Nitecapone-treated diabetic rats were protected from these intracellular modifications. The combined results suggest that the COMT-inhibitory and antioxidant properties of nitecapone provide a protective therapy against the development of diabetic nephropathy.
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PMID:Combined antioxidant and COMT inhibitor treatment reverses renal abnormalities in diabetic rats. 1092 41

Diabetes is associated with a significant increase in thiobarbituric acid reactive substances (TBARS) which are considered as an index of endogenous lipid peroxidation. The human body has a complex antioxidant defense system that prevents the initiation of free radical chain reactions. We measured plasma TBARS levels, superoxide dismutase (SOD) and catalase (CAT) activities and compared their relation to the metabolic control of diabetes and diabetic microangiopathy. Sixty-four patients (19 men), aged 52.35+/-9.31 years with type 2 diabetes mellitus were included in the study. Thirty-six healthy subjects (12 men), aged 51.02+/-7.01 years formed the control group. TBARS levels and SOD activity were elevated in the diabetic group when compared with the control group ( p<0.001 and p<0.00001, respectively). However CAT activity was significantly decreased in the diabetic group when compared with the control group ( p<0.00001). Patients with diabetic nephropathy and retinopathy, but not neuropathy, had elevated TBARS levels but there was no statistically significant difference when compared with diabetic patients without microangiopathy ( p>0.05). There was a positive correlation between plasma TBARS levels and SOD activity (r=0.770, p=0.0001) and a negative correlation between plasma TBARS levels and CAT activity (r=0.482, p=0.0001). There was also a negative correlation between SOD and CAT activities (r=-0.609, p=0.0001). We found significantly elevated TBARS levels in diabetic patients. We did not observe any correlation between TBARS levels and blood glucose and HbA(1c) levels. Elevated TBARS levels and SOD activity and decreased CAT activity may be due to a compensation mechanism of the body.
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PMID:Plasma lipid peroxidation products and antioxidant enzyme activities in patients with type 2 diabetes mellitus. 1235 95


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