8-hydroxy-2--deoxyguanosine and Albuminuria

Diabetic nephropathy (DN) is one of the major microvascular complications of diabetes and it is defined as a rise in the urinary albumin excretion (UAE) rate and abnormal renal function. Currently, changes in albuminuria are considered a hallmark of onset or progression of DN. However, some patients with diabetes have advanced renal pathological changes and progressive kidney function decline even if urinary albumin levels are in the normal range, indicating that albuminuria is not the perfect marker for the early detection of DN. The present article provides an overview of the literature reporting some relevant biomarkers that have been found to be associated with DN and that potentially may be used to predict the onset and/or monitor the progression of nephropathy. In particular, biomarkers of renal damage, inflammation, and oxidative stress may be useful tools for detection at an early stage or prediction of DN. Proteomic-based biomarker discovery represents a novel strategy to improve diagnosis, prognosis and treatment of DN; however, proteomics-based approaches are not yet available in most of the clinical chemistry laboratories. The use of a panel with a combination of biomarkers instead of urinary albumin alone seems to be an interesting approach for early detection of DN, including markers of glomerular damage (e.g., albumin), tubular damage (e.g., NAG and KIM-1), inflammation (e.g., TNF-α) and oxidative stress (e.g., 8-OHdG) because these mechanisms contribute to the development and outcomes of this disease.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Acetylglucosaminidase; Albuminuria; Biomarkers; Deoxyguanosine; Diabetic Nephropathies; Disease Progression; Early Diagnosis; Hepatitis A Virus Cellular Receptor 1; Humans; Inflammation; Kidney; Membrane Glycoproteins; Neoplasm Proteins; Oxidative Stress; Prognosis; Proteomics; Receptors, Virus; Tumor Necrosis Factor-alpha

To study oxidative stress status of early type 2 diabetic nephropathy (DN) patients with subclinical hypothyroidism (SCH) and to assess effect of L-thyroxine therapy on the oxidative stress in these patients.. It is a randomized double-blind and placebo-controlled trial. A total of 48 patients with early type 2 DN were included as Euthyroid group, and 92 early type 2 DN with SCH were selected and randomly assigned to L-thyroxine treatment group (LT4 group) and placebo group (SCH group). Changes in urinary albumin excretion rate (UAER), serum malondialdehyde (MDA), superoxide dismutase (SOD) activity, urine 8-hydroxyl deoxyguanosine (8-OHdG), serum creatinine, estimated glomerular filtration rate, and lipid profile before and after 24 weeks of follow-up were examined and compared.. The levels of UAER, MDA, 8-OHdG were higher, while the SOD activity was lower in DN patients with SCH than in DN patients (p < 0.05 for all). In the LT4 group, the levels of UAER, MDA, 8-OHdG decreased significantly (p < 0.05) to levels no longer different from the Euthyroid group. The SOD activity increased significantly. But in SCH group, the levels of mAlb, MDA, 8-OHdG were greater after 24 weeks of follow-up and greater than patients in the Euthyroid group. SOD activity decreased significantly after 24 weeks in the SCH group (p < 0.05).. Oxidative stress is greater in the DN patients with SCH, and SCH may exacerbate kidney injury in early DN patients. The LT4 treatment may decrease the oxidative stress and attenuate renal injury in DN patient with SCH.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Adult; Albuminuria; Creatinine; Deoxyguanosine; Diabetes Mellitus, Type 2; Diabetic Nephropathies; Double-Blind Method; Female; Glomerular Filtration Rate; Humans; Hypothyroidism; Male; Malondialdehyde; Middle Aged; Oxidative Stress; Superoxide Dismutase; Thyroxine

Dipeptidyl peptidase-4 (DPP-4) inhibitor is a new class of anti-diabetic drug which exerts its glucose-lowering action by suppressing the degradation of a gut incretin hormone glucagon-like peptide-1 (GLP-1). To elucidate whether treatment with stronger DPP-4 inhibitor on top of angiotensin II type 1 receptor blocker (ARB) provides greater renal protective effects, we performed a crossover study with two DPP-4 inhibitors, sitagliptin and alogliptin, in twelve type 2 diabetic patients with incipient nephropathy taking ARBs. This study consisted of three treatment periods: sitagliptin 50 mg/day for 4 weeks (first period), alogliptin 25 mg/day for 4 weeks (second period), and sitagliptin 50 mg/day for 4 weeks (third period). Significant changes in body mass index, blood pressure, serum lipids, serum creatinine, estimated glomerular filtration rate, and HbA1c were not observed among the three treatment periods. Reduced urinary levels of albumin and an oxidative stress marker 8-hydroxy-2'-deoxyguanosine (8-OHdG), increased urinary cAMP levels, and elevated plasma levels of stromal cell-derived factor-1α (SDF-1α) which is a physiological substrate of DPP-4 were observed after the switch from sitagliptin to a stronger DPP-4 inhibitor alogliptin. Given a large body of evidence indicating anti-oxidative action of cAMP and up-regulation of cellular cAMP production by SDF-1α, the present results suggest that more powerful DPP-4 inhibition on top of angiotensin II type 1 receptor blockade would offer additional protection against early-stage diabetic nephropathy beyond that attributed to glycemic control, via reduction of renal oxidative stress by SDF-1α-cAMP pathway activation.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Aged; Albuminuria; Angiotensin II Type 1 Receptor Blockers; Chemokine CXCL12; Cross-Over Studies; Cyclic AMP; Deoxyguanosine; Diabetes Mellitus, Type 2; Diabetic Nephropathies; Dipeptidyl-Peptidase IV Inhibitors; Female; Humans; Male; Middle Aged; Piperidines; Pyrazines; Receptor, Angiotensin, Type 1; Sitagliptin Phosphate; Triazoles; Up-Regulation; Uracil

We have previously demonstrated the increased salt sensitivity of blood pressure (BP) in diabetic patients with early nephropathy. Here, we examined the effects of an angiotensin II receptor blocker (ARB) on salt sensitivity and renal oxidative stress or nitric oxide (NO) in those patients.. Type 2 diabetic patients with (n = 6) and without (n = 6) microalbuminuria were studied on a high-salt diet for one week and on a salt-restricted diet for one week. The study was repeated in the patients with microalbuminuria during treatment with an ARB, valsartan (80 mg/day). Salt sensitivity was assessed from the BP/sodium excretion curve. Urinary excretion rates of NOx, 8-hydroxy-2-deoxyguanosine as a marker of oxidative stress, and plasma tetrahydrobiopterin as a cofactor for NO synthase were measured.. Compared with diabetic patients without microalbuminuria, patients with microalbuminuria showed greater salt sensitivity and lower urinary excretion of NOx. In the patients with microalbuminuria, treatment with valsartan reduced salt sensitivity in association with increased NOx excretion, reduced 8-hydroxy-2,-deoxyguanosine excretion, and increased plasma tetrahydrobiopterin levels.. These data support the hypothesis that ARBs reduce the salt sensitivity of BP by decreasing renal oxidative stress and restoring NO activity in diabetic patients with microalbuminuria.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Albuminuria; Angiotensin Receptor Antagonists; Biopterins; Blood Pressure; Deoxyguanosine; Diabetes Mellitus, Type 2; Diabetic Nephropathies; Female; Hemodynamics; Humans; Kidney; Male; Middle Aged; Nitrates; Nitric Oxide; Nitrites; Receptors, Angiotensin; Sodium Chloride, Dietary; Tetrazoles; Valine; Valsartan

Autosomal dominant polycystic kidney disease (ADPKD) progresses more quickly to end-stage renal disease in patients with hypertension than in their normotensive counterparts. The authors investigated the effect of telmisartan versus enalapril on systolic and diastolic blood pressure (SBP and DBP), urinary albumin excretion (UAE), serum high mobility group box-1 protein (HMGB1), serum interleukin (IL)-6 and urinary 8-hydroxydeoxyguanosine (8-OHdG) levels in patients with hypertensive ADPKD.. Twenty patients with hypertensive ADPKD with good renal function were randomly assigned to 1 of 2 treatments: telmisartan 80 mg once daily (n = 10) or enalapril 10 mg once daily (n = 10). Treatment lasted 12 months. SBP, DBP, serum creatinine, UAE, HMGB1, IL-6 and urinary 8-OHdG levels were measured before and 6 and 12 months after treatment.. Both SBP and DBP were significantly reduced after treatment (P < 0.001) in both groups. Serum creatinine changed little during the experimental period in either group. UAE, serum HMGB1, serum IL-6 and urinary 8-OHdG levels were significantly decreased after treatment (UAE, HMGB1 and IL-6, P < 0.001; and 8-OHdG, P < 0.01 versus baseline levels) in both groups. However, the decreases in UAE, serum HMGB1 and serum IL-6 were significantly greater in the telmisartan group than in the enalapril group at 6 months (P < 0.05, P < 0.01 and P < 0.01, respectively) and 12 months (all, P < 0.05).. Telmisartan seems to be equivalent to enalapril in lowering BP, but telmisartan has more potent renoprotective, anti-inflammatory and antioxidative effects than enalapril in patients with hypertensive ADPKD.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Aged; Albuminuria; Angiotensin-Converting Enzyme Inhibitors; Benzimidazoles; Benzoates; Biomarkers; Creatinine; Deoxyguanosine; Enalapril; Female; HMGB1 Protein; Humans; Hypertension; Inflammation; Interleukin-6; Male; Middle Aged; Oxidative Stress; Polycystic Kidney, Autosomal Dominant; Telmisartan

This open-label, randomized, parallel-controlled study investigated the effects of the direct renin inhibitor aliskiren on 64 hypertensive type 2 diabetic patients with chronic kidney disease (CKD) and stable glycemic control who were already being treated with fixed doses of antihypertensive agents over a 24-week period. These agents were 80 mg of the angiotensin II receptor blocker (ARB) telmisartan and 5 mg of the calcium channel blocker (CCB) amlodipine. Patients were randomly assigned to two groups: the aliskiren group, receiving 150 mg per day aliskiren, which was increased to 300 mg per day (n=32), and the CCB group, which received an increased dose (7.5 mg per day) of amlodipine that was increased to 10 mg per day (n=32). Urinary albumin excretion and urinary levels of 8-hydroxy-2'-deoxyguanosine (8-OHdG) and liver-type fatty acid-binding protein (L-FABP) were investigated in each group. Mean systolic and diastolic blood pressure decreased significantly in both groups, but there was no significant difference between the two groups at the end of the study. Serum creatinine levels and estimated glomerular filtration rate did not differ significantly between the two groups, but percent changes of urinary albumin/creatinine ratios, 8-OHdG and L-FABP levels decreased significantly in the aliskiren group compared with the CCB group. Plasma aldosterone levels were significantly decreased in the aliskiren group, which correlated significantly with those of urinary 8-OHdG and L-FABP. Our results suggest that the addition of aliskiren to the maximal recommended dose of ARB and usual dose of amlodipine is more effective in reducing albuminuria and oxidant stress in hypertensive diabetic patients with CKD than increasing the dose of amlodipine.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Adult; Aged; Albuminuria; Aldosterone; Amides; Amlodipine; Angiotensin II Type 2 Receptor Blockers; Antihypertensive Agents; Benzimidazoles; Benzoates; Blood Pressure; Calcium Channel Blockers; Deoxyguanosine; Diabetes Mellitus, Type 2; Diabetic Nephropathies; Dose-Response Relationship, Drug; Enzyme-Linked Immunosorbent Assay; Fatty Acid-Binding Proteins; Female; Fumarates; Glomerular Filtration Rate; Glycated Hemoglobin; Humans; Male; Middle Aged; Renin; Telmisartan; Young Adult

We examined the effect of mercury (Hg) associated with dental amalgam fillings on biomarkers of renal and oxidative stress in children between the ages of 5-15.5 years. Urine samples were analyzed for N-acetyl-β-D-glucosaminidase (NAG), α(1)-microglobulin (α(1)-MG), β(2)-microglobulin (β(2)-MG), retinol binding protein (RBP), albumin (ALB), 8-hydroxy-2-deoxyguanosine (8-OHdG) and malondialdehyde (MDA). The level of urinary Hg (UHg-C) was calculated as μg/g creatinine. Multiple regression analyses revealed that the excretion of urinary NAG was significantly associated with the presence of dental amalgam fillings (β=0.149, P=0.03) and the levels of UHg-C (β=0.531, P=0), with an interaction between the two (P=0). The increase in urinary NAG in relation to UHg-C levels had a dose-effect pattern. The lowest observed effect was seen at UHg-C levels above 1.452 μg/g creatinine, which is lower than previously reported. In contrast, α(1)-MG was negatively associated with the presence of dental amalgam fillings (β=-0.270, P=0), but positively with UHg-C levels (β=0.393, P=0). There were 7 children without, and one child with, dental amalgam fillings with urinary α(1)-MG levels above the reference limit of >7 mg/g creatinine. Even though α(1)-MG seems to be a reliable biomarker for early changes in renal functions, it might exert its effect only at a higher level of exposure. An inverse relationship was also observed between urinary 8-OHdG levels and the presence of dental amalgam fillings. This might suggest that the dental amalgam does not increase DNA damage but reduces the capacity to repair DNA, leading to lower urinary excretion of 8-OHdG. On the other hand, we found that Hg affected the excretion of urinary 8-OHdG in a dose-related pattern that was mostly associated with long-term exposure to low Hg levels. Urinary NAG levels were positively associated with urinary MDA levels (β=0.516, P=0) but not with 8-OHdG (β=0.134, P=0.078) after adjustment for potential confounders. Both UHg-C and the presence of dental amalgam fillings remained predictors of the NAG model. Our data provide evidence that low exposure to Hg from dental amalgam fillings exerts an effect on kidney tubular functions in children. Oxidative stress may have played a role in this mechanism. The results of this study would also suggest that urinary NAG is the most sensitive of all the investigated renal biomarkers. These results should be confirmed with further investigation.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Acetylglucosaminidase; Adolescent; Albuminuria; Alpha-Globulins; beta 2-Microglobulin; Biomarkers; Child; Child, Preschool; Dental Amalgam; Deoxyguanosine; Dose-Response Relationship, Drug; Female; Humans; Kidney; Male; Malondialdehyde; Mercury; Oxidative Stress; Predictive Value of Tests; Regression Analysis; Retinol-Binding Proteins

Cilnidipine, an L/N-type calcium channel blocker (CCB), has been reported to have more beneficial effects on proteinuria progression in hypertensive patients than amlodipine, an L-type CCB. The N-type calcium channel blockade that inhibits renal sympathetic nerve activity might reduce glomerular hypertension by facilitating vasodilation of the efferent arterioles. However, the precise mechanism of the renoprotective effect of cilnidipine remains unknown. Because cilnidipine exerted significantly higher antioxidant activity than amlodipine in cultured human mesangial cells, we hypothesized that cilnidipine might exert a renoprotective effect by suppressing oxidative stress. A total of 35 hypertensive patients receiving a renin-angiotensin system inhibitor were randomly assigned to a cilnidipine (n=18; 10 mg per day cilnidipine titrated to 20 mg per day) or amlodipine (n=17; 5 mg per day amlodipine titrated to 10 mg per day) group; the target blood pressure (BP) was set at 130/85 mmHg. After 6 months of treatment, systolic and diastolic BPs were significantly reduced in both of the groups, without any significant difference between the groups. The urinary albumin, 8-hydroxy-2'-deoxyguanosine (OHdG) and liver-type fatty-acid-binding protein (L-FABP) to creatinine ratios significantly decreased in the cilnidipine group (P<0.05) compared with those in the amlodipine group. The reductions in urinary albumin, 8-OHdG and L-FABP were not correlated with the change in systolic BP. In conclusion, cilnidipine, but not amlodipine, ameliorated urinary albumin excretion and decreased urinary 8-OHdG and L-FABP in the hypertensive patients. Cilnidipine probably exerts a greater renoprotective effect through its antioxidative properties.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Aged; Albuminuria; Amlodipine; Antihypertensive Agents; Antioxidants; Blood Pressure; Calcium Channel Blockers; Deoxyguanosine; Dihydropyridines; Fatty Acid-Binding Proteins; Female; Heart Rate; Humans; Hypertension; Incidence; Male; Middle Aged; Oxidative Stress; Prospective Studies; Renal Insufficiency, Chronic

Dyslipidemia is a common complication of chronic kidney disease (CKD) and contributes to cardiovascular morbidity and mortality of CKD patients.. The aim of the present study was to determine whether fluvastatin, which is mostly characterized by its pleiotropic anti-oxidant effects, has renoprotective effects in dyslipidemic patients with CKD.. In 43 dyslipidemic patients with CKD taking fluvastatin 10 mg/day, 20 mg/day or 30 mg/day, renal functions as well as lipid profiles were assessed.. After 3 months of treatment with fluvastatin, LDL-cholesterol level significantly decreased. Serum creatinine level, estimated glomerular filtration rate (eGFR), urinary albumin excretion (UAE), urinary liver-type fatty acid binding protein (L-FABP) level and urinary 8-hydroxydeoxyguanosine (8-OHdG) level did not change in overall patients. However, in patients with microalbuminuria (baseline UAE ≥ 30 mg/g·creatinine; n = 23), the UAE significantly decreased [2.43 ± 0.67 to 1.98 ± 0.80 log(mg/g·creatinine), p = 0.01]. In patients with high L-FABP group (baseline L-FABP ≥ 11 µg/g·creatinine; n = 18), the urinary L-FABP level was significantly decreased (1.52 ± 0.45 to 1.26 ± 0.43 µg/g·creatinine, p < 0.01). In the limited 23 patients with microalbuminuria, the L-FABP level was significantly decreased [1.20 ± 0.62 to 1.03 ± 0.49 log(µg/g·creatinine), p = 0.042], although the LDL-cholesterol level (139 ± 28 to 129 ± 23 mg/dL, p = 0.08) only showed a tendency to decrease. The 8-OHdG level also was significantly decreased (13.6 ± 9.6 to 9.8 ± 3.8 ng/g·creatinine, p = 0.043). In the overall patients, changes in the values for UAE and urinary L-FABP were not correlated with the changes in LDL-levels.. Fluvastatin reduces both UAE and the urinary L-FABP level, and thus, has renoprotective effects, independent of its lipid lowering effects in dyslipidemic patients with CKD.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Aged; Aged, 80 and over; Albuminuria; Cholesterol, LDL; Creatinine; Deoxyguanosine; Dyslipidemias; Fatty Acid-Binding Proteins; Fatty Acids, Monounsaturated; Female; Fluvastatin; Glomerular Filtration Rate; Humans; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Indoles; Male; Renal Insufficiency, Chronic; Treatment Outcome

Growing evidence indicates that oxidative stress induced by excessive superoxide has a central role in the pathogenesis of diabetic nephropathy (DN). Telmisartan, one of the currently available angiotensin II type 1 receptor blockers (ARBs), has been shown to exert a more powerful proteinuria (albuminuria) reduction in patients with DN, but whether the prominent renoprotective effect of telmisartan is mediated through enhancing antioxidant defense capacity and reducing oxidative stress has not been fully elucidated. The present study first revealed that the serum activity of superoxide dismutase (SOD) responsible for superoxide removal is reduced in the DN stage of microalbuminuria, but not in normoalbuminuria in type 2 diabetic patients. We next examined the alteration of SOD and oxidative stress following an 8-week treatment with telmisartan (40 mg per day) in 12 type 2 diabetic patients with microalbuminuria. Interestingly, the telmisartan treatment not only reduced the circulating levels of two oxidative stress markers, 8-hydroxy-2'-deoxyguanosine (8-OHdG) and nitrotyrosine (NT), but also enhanced serum SOD activity. Notably, a significant correlation was observed between the increase in serum SOD activity and the reduction in albuminuria. We further compared the anti-oxidative effect of telmisartan with that of losartan, another member of the ARB class, by implementing an 8-week interval crossover treatment with these ARBs in another 12 microalbuminuric type 2 diabetic patients. The patients showed higher serum SOD activity, and lower circulating levels of 8-OHdG and NT, during treatment with telmisartan than with losartan. These results suggest that telmisartan has a more potent antioxidative effect through its ability to enhance SOD activity in type 2 diabetic patients with microalbuminuria.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Aged; Albuminuria; Angiotensin II Type 1 Receptor Blockers; Antioxidants; Benzimidazoles; Benzoates; Cross-Over Studies; Deoxyguanosine; Diabetes Mellitus, Type 2; Diabetic Nephropathies; Female; Humans; Japan; Losartan; Male; Middle Aged; Nitric Oxide; Oxidative Stress; Superoxide Dismutase; Telmisartan; Tyrosine

The factors determining the course of glomerular filtration rate (GFR) and albumin excretion rate (AER) and the expression of mRNA of slit diaphragm (SD) and podocyte proteins in microalbuminuric, hypertensive type II diabetic patients are not fully understood. GFR, AER, and SD protein mRNA were studied in 86 microalbuminuric, hypertensive, type II diabetics at baseline and after 4-year random double-blind treatment either with 40 mg simvastatin (Group 1) or with 30 g cholestyramine (Group 2) per day. Both groups had at baseline a GFR decay per year in the previous 2-4 years of 3 ml/min/1.73 m(2). Both Groups 1 and 2 showed a significant decrease of low-density lipoprotein cholesterol levels after simvastatin and cholestyramine treatment (P<0.01). No change from base line values was observed as for hs-C-reactive protein and interleukin-6. A significant decrease of 8-hydroxydeoxyguanosine urinary excretion was observed after simvastatin treatment. GFR did not change from baseline with simvstatin, whereas a decrease was observed with cholestyramine treatment (simvastatin vs cholestyramine: -0.21 vs -2.75 ml/min/1.73 m(2), P<0.01). AER decreased in Group 1 (P<0.01), but not in Group 2 patients. Real-time polymerase chain reaction measurement of mRNA SD proteins (CD2AP, FAT, Actn 4, NPHS1, and NPHS2) significantly increased in kidney biopsy specimens after simvastatin, but not cholestyramine treatment. Simvastatin, but not cholestyramine, 4-year treatment maintains steady patterns of GFR, and improves AER and expression of SD proteins in type II diabetes, despite similar hypocholesterolemic effects in circulation.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Aged; Albumins; Albuminuria; Anticholesteremic Agents; Cholestyramine Resin; Deoxyguanosine; Diabetes Mellitus, Type 2; Female; Glomerular Filtration Rate; Humans; Kidney Glomerulus; Lipids; Male; Middle Aged; Podocytes; Proteins; RNA, Messenger; Simvastatin

The role of exendin-4 in brown adipose tissue (BAT) activation was not very clear. This study is to verify the role of BAT involved in renal benefits of exendin-4 in diabetes mellitus (DM).. In vivo, C57BL/6 mice were randomly divided into nondiabetic (control) and diabetic groups (DM). The diabetic mice were randomized into a control group (DM-Con), BAT-excision group (DM+Exc), exendin-4-treated group (DM+E4), and BAT-excision plus exendin-4-treated group (DM+Exc+E4). The weight, blood glucose and lipids, 24 h urine albumin and 8-OH-dG, and renal fibrosis were analyzed. In vitro, we investigated the role of exendin-4 in the differentiation process of 3T3-L1 and brown preadipocytes and its effect on the rat mesangial cells induced by oleate.. The expressions of UCP-1, PGC-1. Exendin-4 could decrease the renal lipid deposit and improve diabetic nephropathy via activating the renal AMPK pathway independent of BAT activation.

Topics: 3T3-L1 Cells; 8-Hydroxy-2'-Deoxyguanosine; Adenylate Kinase; Adipocytes, Brown; Adipogenesis; Adipose Tissue, Brown; Albuminuria; Animals; Blood Glucose; Blotting, Western; Body Weight; CD36 Antigens; Cholesterol, HDL; Cholesterol, LDL; Diabetes Mellitus, Type 2; Diabetic Nephropathies; Disease Models, Animal; Exenatide; Fibrosis; Gene Expression; Incretins; Kidney; Lipase; Mesangial Cells; Mice; Mice, Inbred C57BL; Myofibroblasts; Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; Random Allocation; Rats; Real-Time Polymerase Chain Reaction; Triglycerides; Uncoupling Protein 1

Although hyperuricemia is shown to accelerate chronic kidney disease, the mechanisms remain unclear. Accumulating studies also indicate that uric acid has both pro- and antioxidant properties. We postulated that hyperuricemia impairs the function of glomerular podocytes, resulting in albuminuria. Hyperuricemic model was induced by oral administration of 2% oxonic acid, a uricase inhibitor. Oxonic acid caused a twofold increase in serum uric acid levels at 8 weeks when compared to control animals. Hyperuricemia in this model was associated with the increase in blood pressure and the wall-thickening of afferent arterioles as well as arcuate arteries. Notably, hyperuricemic rats showed significant albuminuria, and the podocyte injury marker, desmin, was upregulated in the glomeruli. Conversely, podocin, the key component of podocyte slit diaphragm, was downregulated. Structural analysis using transmission electron microscopy confirmed podocyte injury in this model. We found that urinary 8-hydroxy-2'-deoxyguanosine levels were significantly increased and correlated with albuminuria and podocytopathy. Interestingly, although the superoxide dismutase mimetic, tempol, ameliorated the vascular changes and the hypertension, it failed to reduce albuminuria, suggesting that vascular remodeling and podocyte injury in this model are mediated through different mechanisms. In conclusion, vasculopathy and podocytopathy may distinctly contribute to the kidney injury in a hyperuricemic state.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Actins; Albuminuria; Animals; Blood Pressure; Cyclic N-Oxides; Deoxyguanosine; Desmin; Disease Models, Animal; Hyperuricemia; Immunohistochemistry; Kidney Glomerulus; Male; Microscopy, Electron, Transmission; Oxidative Stress; Oxonic Acid; Rats; Rats, Sprague-Dawley; Spin Labels; Urate Oxidase; Uric Acid; Xanthine Dehydrogenase

Topics: 8-Hydroxy-2'-Deoxyguanosine; Acetylation; Age Factors; Aging; Albuminuria; Animals; Cell Cycle Proteins; Cellular Senescence; Deoxyguanosine; Forkhead Box Protein O3; Forkhead Transcription Factors; Gene Knockdown Techniques; Genotype; Glomerulonephritis; Mice; Oxidative Stress; Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; Phenotype; Podocytes; Renal Insufficiency, Chronic; RNA Interference; RNA, Small Interfering; Signal Transduction; Sirtuin 1; Transcription Factor RelA

Epidemiological studies show that 5-40 % of type 2 diabetes (T2DM) patients have diabetic nephropathy, and oxidative stress is one of several underlying mechanisms. We investigated associations between oxidative stress markers and severity of diabetic nephropathy.. Fifty-nine T2DM patients from the endocrinology outpatient department were included, and their levels of oxidative stress markers were measured. Three groups were determined by their urine albumin-to-creatinine ratio (UACR): group A (UACR < 30 mg/g, n = 22); group B (30 ≤ UACR < 300 mg/g, n = 22); and group C (UACR ≥ 300 mg/g, n = 15).. Vitamin C levels correlated negatively and moderately with serum creatinine (γ = -0.459, p < 0.001), urine albumin (γ. Our results identified several oxidative stress markers that may be clinically important in diabetic nephropathy. Studies with larger sample sizes should be undertaken to confirm these findings.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Aged; Albuminuria; Antioxidants; Ascorbic Acid; Biomarkers; Creatinine; Deoxyguanosine; Diabetes Mellitus, Type 2; Diabetic Nephropathies; Female; Glomerular Filtration Rate; Humans; Male; Middle Aged; Oxidative Stress; Predictive Value of Tests; Prognosis; Prospective Studies; Severity of Illness Index

The molecular signaling mechanisms between glomerular cell types during initiation/progression of diabetic kidney disease (DKD) remain poorly understood. We compared the early transcriptome profile between DKD-resistant C57BL/6J and DKD-susceptible DBA/2J (D2) glomeruli and demonstrated a significant downregulation of essential mitochondrial genes in glomeruli from diabetic D2 mice, but not in C57BL/6J, with comparable hyperglycemia. Diabetic D2 mice manifested increased mitochondrial DNA lesions (8-oxoguanine) exclusively localized to glomerular endothelial cells after 3 weeks of diabetes, and these accumulated over time in addition to increased urine secretion of 8-oxo-deoxyguanosine. Detailed assessment of glomerular capillaries from diabetic D2 mice demonstrated early signs of endothelial injury and loss of fenestrae. Glomerular endothelial mitochondrial dysfunction was associated with increased glomerular endothelin-1 receptor type A (Ednra) expression and increased circulating endothelin-1 (Edn1). Selective Ednra blockade or mitochondrial-targeted reactive oxygen species scavenging prevented mitochondrial oxidative stress of endothelial cells and ameliorated diabetes-induced endothelial injury, podocyte loss, albuminuria, and glomerulosclerosis. In human DKD, increased urine 8-oxo-deoxyguanosine was associated with rapid DKD progression, and biopsies from patients with DKD showed increased mitochondrial DNA damage associated with glomerular endothelial EDNRA expression. Our studies show that DKD susceptibility was linked to mitochondrial dysfunction, mediated largely by Edn1-Ednra in glomerular endothelial cells representing an early event in DKD progression, and suggest that cross talk between glomerular endothelial injury and podocytes leads to defects and depletion, albuminuria, and glomerulosclerosis.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Adult; Aged; Albuminuria; Animals; Antioxidants; Chromatography, High Pressure Liquid; Deoxyguanosine; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 1; Diabetic Nephropathies; Disease Susceptibility; DNA, Mitochondrial; Endothelin-1; Endothelium; Enzyme-Linked Immunosorbent Assay; Female; Flow Cytometry; Humans; Kidney Glomerulus; Male; Mesangial Cells; Mice; Mice, Inbred C57BL; Mice, Inbred DBA; Microscopy, Electron, Scanning; Middle Aged; Mitochondria; Organophosphorus Compounds; Oxygen Consumption; Piperidines; Podocytes; Real-Time Polymerase Chain Reaction; Receptor, Endothelin A; Signal Transduction; Young Adult

Expression of klotho, the renoprotective anti-aging gene, is decreased in diabetic model kidneys. We hypothesized that klotho protein attenuates renal hypertrophy and glomerular injury in a mouse model of diabetic nephropathy.. Klotho transgenic (KLTG) mice were crossed with spontaneously diabetic Ins2Akita (AKITA) mice. Glomerular morphology, macrophage infiltration, urinary albumin excretion and urinary 8-hydroxy-2-deoxy guanosine excretion were examined. In vitro, human glomerular endothelial cells were stimulated with high glucose with or without recombinant klotho, and calpain activity and proinflammatory cytokine expressions were measured.. We found that klotho protein overexpression attenuates renal hypertrophy and glomerular injury in this mouse model of diabetic nephropathy. Klotho overexpression attenuated renal hypertrophy, albuminuria, glomerular mesangial expansion, and endothelial glycocalyx loss in the AKITA mice. AKITA mice exhibit high levels of urinary 8-hydroxy-2-deoxy guanosine excretion. In the presence of klotho overexpression, this effect was reversed. In addition, the glomerular macrophage infiltration characteristic of AKITA mice was attenuated in KLTG-AKITA mice. In human glomerular endothelial cells, high glucose induced calpain activity. This effect was suppressed by expression of recombinant klotho, which also suppressed the induction of proinflammatory cytokines.. Our data suggest klotho protein protects against diabetic nephropathy through multiple pathways.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Albuminuria; Animals; Biomarkers; Calpain; Cells, Cultured; Deoxyguanosine; Diabetes Mellitus; Diabetic Nephropathies; Disease Models, Animal; Genotype; Glucose; Glucuronidase; Humans; Hypertrophy; Inflammation Mediators; Kidney Glomerulus; Klotho Proteins; Macrophages; Mice, Inbred C57BL; Mice, Transgenic; Phenotype; Transfection

Podocytes participate in the formation and regulation of the glomerular filtration barrier. Loss of podocytes occurs during the early stages of diabetic nephropathy and impairs glomerular filtration. Dipeptidyl peptidase-4 (DPP-4) inhibitors are widely used as anti-diabetic agents in clinical practice. In this study, we showed that gemigliptin, a novel DPP-4 inhibitor, reduced podocyte apoptosis in type 2 diabetic db/db mice without reducing hyperglycemia. Gemigliptin (100mg/kg/day) was administered orally for 12 weeks in db/db mice. Blood glucose levels and albuminuria were measured. The renal cortex was collected for histological examination, and molecular assays were used to detect 8-hydroxydeoxyguanosine, advanced oxidation protein products (AOPP), the receptor for advanced glycation end products (RAGE), and integrin-linked kinase (ILK). Type 2 diabetic db/db mice exhibited albuminuria, renal histopathological changes, and podocyte loss. Administration of gemigliptin to db/db mice suppressed albuminuria, enzyme activity and expression of DPP-4, and podocyte apoptosis. The effect of gemigliptin on diabetes-induced podocyte loss was associated with the suppression of oxidative damage, AOPP accumulation, RAGE expression, and ILK expression. These results indicate the possible benefits of using gemigliptin in diabetes patients to treat renal impairment without affecting glycemic control.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Advanced Oxidation Protein Products; Albuminuria; Animals; Apoptosis; Blood Glucose; Cytoprotection; Diabetes Mellitus, Type 2; Diabetic Nephropathies; Dipeptidyl Peptidase 4; Dipeptidyl-Peptidase IV Inhibitors; Disease Models, Animal; Glomerular Filtration Rate; Guanine; Male; Mice, Inbred C57BL; Piperidones; Podocytes; Protein Serine-Threonine Kinases; Pyrimidines; Receptor for Advanced Glycation End Products

We previously showed that urine and serum Angiopoietin-2 (Ang-2) levels increased significantly with the degree of albuminuria in diabetes patients, but the reasons remain unclear. Consequently we aimed to determine whether there was an association between Ang-2, inflammatory cytokines (TNF-α and IL-18) and reactive oxygen species (8-OHdG and SOD) in type 2 diabetes patients with albuminuria.. This retrospective study evaluated 113 patients with type 2 diabetes and normoalbuminuria, microalbuminuria, or macroalbuminuria and 30 healthy controls. Serum and urine TNF-α, IL-18 and 8-OHdG levels were measured by ELISA. Superoxide dismutase (SOD) activity was determined by spectrophotometry.. Serum and urine TNF-α, IL-18 and 8-OHdG levels increased significantly with the degree of albuminuria, and were positively correlated with increased Ang-2. In contrast, SOD activity decreased with the degree of albuminuria and was negatively correlated with Ang-2. Multivariable linear regression analysis revealed that serum Ang-2 level was independently associated with serum levels of TNF-α (P<0.001), 8-OHdG (P=0.001), and IL-18 (P=0.003). Urinary Ang-2 level was independently associated with urinary TNF-α (P<0.001) and 8-OHdG (P=0.004) levels.. TNF-α and 8-OHdG are associated with elevated urinary Angiopoietin-2 levels in type 2 diabetic patients with albuminuria.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Adult; Albuminuria; Angiopoietin-2; Cross-Sectional Studies; Deoxyguanosine; Diabetes Mellitus, Type 2; Female; Humans; Interleukin-18; Kidney Glomerulus; Male; Middle Aged; NADPH Oxidase 4; NADPH Oxidases; Reactive Oxygen Species; Retrospective Studies; Superoxide Dismutase; Superoxide Dismutase-1; Tumor Necrosis Factor-alpha

Oxidative stress and inflammation are known to play central roles in the development of diabetic nephropathy (DN). Febuxostat is a novel non-purine xanthine oxidase (XO)-specific inhibitor developed to treat hyperuricemia. In this study, we investigated whether febuxostat could ameliorate DN via renoprotective mechanisms such as alleviation of oxidative stress and anti-inflammatory actions.. Male Sprague-Dawley rats were divided into three groups: a normal group, a diabetes group (DM group), and a febuxostat-treated diabetes group (DM+Fx group). We administered 5 mg/kg of febuxostat to experimental rats for 7 weeks and evaluated clinical and biochemical parameters and XO and xanthine dehydrogenase (XDH) activity in hepatic tissue. The degree of oxidative stress and extent of inflammation were evaluated from urine samples and renal tissue collected from each group.. Diabetic rats (DM and DM+Fx groups) had higher blood glucose and kidney weight relative to body weight than normal rats. Albuminuria was significantly reduced in febuxostat-treated diabetic rats compared with untreated diabetic rats. Quantitative analysis showed that hepatic XO and XDH activities were higher in the DM groups, but decreased after treatment with febuxostat. Urinary 8-OHdG concentrations and renal cortical nitrotyrosine also indicated reduced oxidative stress in the DM+Fx group relative to the DM group. The number of ED-1-stained cells in the glomerulus and tubule of diabetic renal tissue decreased in febuxostat-treated diabetic rats relative to that of non-treated diabetic rats. Diabetic rats also expressed higher transcript levels of inflammatory genes (E-selectin and VCAM-1), an inflammation-induced enzyme (COX-2), and inflammatory mediators (ED-1 and NF-κB) than control rats; expression of these genes was significantly reduced by treatment with febuxostat.. Febuxostat prevents diabetic renal injury such as albuminuria. This renoprotective effect appears to be due to attenuation of the inflammatory and oxidative effects of diabetes-induced renal damage through inhibition of XO and XDH activities.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Albuminuria; Animals; Antibiotics, Antineoplastic; Cyclooxygenase 2; Deoxyguanosine; Diabetes Mellitus, Experimental; Diabetic Nephropathies; Ectodysplasins; Febuxostat; Gout Suppressants; Kidney; Liver; Male; NF-kappa B; Oxidative Stress; Rats; Rats, Sprague-Dawley; RNA, Messenger; Streptozocin; Thiazoles; Xanthine Dehydrogenase; Xanthine Oxidase

Chronic kidney disease (CKD) is a serious health problem worldwide. Therapies that can halt the progression of CKD are limited, and the identification of new strategies for CKD treatment is therefore important. Pitavastatin, one of the newest statins introduced to the market, has been shown to exhibit some beneficial effects on renal and endothelial function.. We enrolled 12 healthy volunteers for our study. With or without pitavastatin administration, creatinine clearance (Ccr), urinary albumin excretion, lipid status, and oxidative stress markers were evaluated in acute and early phases after administration of the drug.. A single pitavastatin administration increased Ccr and reduced oxidative stress parameters, such as 8-OHdG levels and isoprostane production, within 6 h, without altering lipid status in healthy participants. A two-week treatment with pitavastatin lowered total and LDL cholesterol and triglycerides but not HDL cholesterol at 7 and 14 days. This change in lipid profile is associated with enhanced Ccr and the suppression of oxidative stress parameters. Urinary albumin excretion was reduced after either acute or chronic administration of pitavastatin, although this effect was not yet significant.. We found that pitavastatin augmented Ccr and reduced oxidative stress parameters in healthy subjects. These data suggest that pitavastatin affects renal outcomes in both lipid status-dependent and -independent manners. These observations suggest that pitavastatin treatment could be beneficial for CKD patients.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Adult; Albuminuria; Algorithms; Cholesterol, LDL; Creatinine; Deoxyguanosine; Female; Humans; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Isoprostanes; Lipids; Male; Middle Aged; Nitric Oxide; Oxidative Stress; Quinolines

Cyclosporine, a potent immunosuppressant, has nephrotoxic adverse effects that may be mediated by oxidative stress. The reduced form of coenzyme Q10 has antioxidant effects. The aim of the present study was to evaluate the effect of the reduced form of coenzyme Q10 on cyclosporine nephrotoxicity.. Six-week-old male Wistar rats were divided into 3 groups (10 animals each). Group 1 (control) received olive oil only. Group 2 received cyclosporine (30 mg/kg/d, which is an experimentally nephrotoxic dose). Group 3 received cyclosporine (30 mg/kg/d) and the reduced form of coenzyme Q10 (600 mg/kg/d). The cyclosporine and the reduced form of coenzyme Q10 were given orally for 4 weeks. Daily urinary albumin excretion, serum creatinine level, and urinary 8-hydroxydeoxyguanosine level were measured, and renal tissue was evaluated by immunohistochemistry.. In rats treated with cyclosporine and the reduced form of coenzyme Q10 (group 3), there were significantly less abnormalities in mean urinary albumin excretion (group 1: 2.8 ± 0.5; group 2: 41 ± 7; group 3: 21 ± 4 μg/d), serum creatinine (group 1: 1.0 ± 0.2; group 2: 1.8 ± 0.4; group 3: 1.4 ± 0.3 mg/dL), and urine 8-hydroxydeoxyguanosine levels (group 1: 7 ± 3; group 2: 10 ± 3; group 3: 7 ± 1 mg/mL creatinine) than rats treated with cyclosporine alone (group 2). There were 8-hydroxydeoxyguanosine deposits seen in the proximal tubular cells of group 2 that were not present in rats treated with the reduced form of coenzyme Q10 (group 3).. The reduced form of coenzyme Q10 may prevent or minimize cyclosporine nephrotoxicity by an antioxidant effect.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Administration, Oral; Albuminuria; Animals; Creatinine; Cyclosporine; Deoxyguanosine; Immunosuppressive Agents; Kidney; Male; Models, Animal; Oxidative Stress; Prevalence; Rats; Rats, Wistar; Ubiquinone

Measurement of urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) has recently become more popular as a means of assessing oxidative stress in the human body. The aim of this study is to compare the levels of urine 8-OHdG in patients with type 2 diabetes with and without nephropathy and to evaluate its role as a biochemical marker for distinguishing these patients from healthy and patients without complications.. For this purpose, 52 patients with type 2 diabetes mellitus (32 with nephropathy (DMN), 20 without nephropathy (DM)) and 20 healthy control subjects (C) were included in this study. The urine concentrations of 8-OHdG were measured by modified LC-MS/MS method and compared with the first morning voiding urine albumin/creatinine ratio (UACR) and HbA1c values of the same patients.. The concentrations of urine 8-OHdG in DMN and DM patients were higher than those of the control subjects (3.47 ± 0.94, 2.92 ± 1.73, 2.1 ± 0.93 nmol/mol creatinine, respectively). But there was no statistical difference between DMN and DM (p = 0.115). There is significant correlation between urinary 8-OHdG and UACR (r = 0.501, p < 0.001). According to ROC analysis, the AUC value of HbA1c was higher than the value of the AUC of 8-OHdG (0.882 and 0.771, respectively).. This study shows that the urine 8-OHdG levels increase in diabetic patients. However, urinary 8-OHdG is not a useful clinical marker, compared with UACR, to predict the development of diabetic nephropathy in diabetic patients.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Albuminuria; Biomarkers; Case-Control Studies; Creatinine; Deoxyguanosine; Diabetes Mellitus, Type 2; Diabetic Nephropathies; Female; Glycated Hemoglobin; Humans; Male; Mass Spectrometry; Middle Aged; Reactive Oxygen Species; Tandem Mass Spectrometry

Hyperglycemia promotes oxidative stress and hence generation of reactive oxygen species (ROS), which is known to play a crucial role in the pathogenesis of diabetic nephropathy. Metformin, an oral hypoglycemic drug, possesses antioxidant effects. The aim of this paper is to investigate the protective effects of metformin on the injury of renal podocytes in spontaneously diabetic Torii (SDT) rats, a new model for nonobese type 2 diabetes. Metformin (350 mg/kg/day) was given to SDT rats for 17 weeks. Blood glucose, glycated haemoglobin (HbA1c), and albuminuria were examined. Kidney histopathology, renal 8-hydroxydeoxyguanosine (8-OHdG) levels and apoptosis were examined. In 43-week-old SDT rats, severe hyperglycemia was developed, and albuminuria was markedly increased. Diabetes induced significant alterations in renal glomerular structure. In addition, urinary and renal 8-OHdG levels were highly increased, and podocyte loss was shown through application of the TUNEL and synaptopodin staining. However, treatment of SDT rats with metformin restored all these renal changes. Our data suggested that diabetes-induced podocyte loss in diabetic nephropathy could be suppressed by the antidiabetes drug, metformin, through the repression of oxidative injury.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Albuminuria; Animals; Antioxidants; Apoptosis; Deoxyguanosine; Diabetes Mellitus, Type 2; Diabetic Nephropathies; Disease Models, Animal; DNA Fragmentation; Hypoglycemic Agents; Kidney; Male; Metformin; Microfilament Proteins; Oxidative Stress; Podocytes; Random Allocation; Rats; Rats, Inbred Strains; Rats, Sprague-Dawley

Diabetic nephropathy is characterized by abnormal angiogenesis, and this is driven by several factors, including hyperglycaemia and ischaemia. We investigated the role of vascular endothelial growth factor receptor-2 (VEGFR-2) blockade and its effects on diabetic nephropathy.. Male db/db and db/m mice received long-term treatment with dRK6, an arginine-rich anti-VEGF hexapeptide, for 12 weeks or short-term treatment for only the first 4 weeks, starting from 8 weeks of age.. The urinary albuminuria and VEGF excretion varied according to the duration of diabetes, and the urinary VEGF levels were strongly correlated with the levels of albuminuria. Diabetes increased the VEGFR-2 expression in the kidneys. At the end of the 12-week study, compared with the db/db control mice, the db/db mice with long-term dRK6 treatment, which selectively inhibited VEGFR-2, had more albuminuria, related to weak nephrin signalling and advanced renal phenotypes, which were associated with hypoxia-oxidative stress, and an increased number of apoptotic endothelial cells. Interestingly, these changes were related to a decrease in phospho-Akt/eNOS-NO bioavailability. On the in vitro study, dRK6 increased the number of apoptotic human umbilical vein endothelial cells (HUVECs) in the high glucose media by blocking phospho-Akt/eNOS-NO signalling, and this was related to the increased oxidative stress. The short-term inhibition of VEGFR-2 neither improved the albuminuria nor the renal phenotype induced by diabetes.. Long-term selective blockade of VEGFR-2 by dRK6 had deleterious renal effects, and this was associated with downregulation of the Akt/eNOS-NO axis in db/db mice. Short-term VEGFR-2 blockade did not improve the renal phenotypes and the albuminuria. These findings suggest that VEGF-A-VEGFR-2 inhibition, regardless of how long it may be, does not ameliorate diabetic nephropathy in type 2 diabetes.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Albuminuria; Animals; Apoptosis; Blotting, Western; Cell Proliferation; Deoxyguanosine; Diabetes Mellitus, Type 2; Diabetic Nephropathies; Endothelium, Vascular; Immunoenzyme Techniques; Male; Mice; Mice, Inbred C57BL; Mice, Mutant Strains; Nitric Oxide; Nitric Oxide Synthase Type III; Obesity; Oligopeptides; Proto-Oncogene Proteins c-akt; Renal Insufficiency; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Signal Transduction; Vascular Endothelial Growth Factor A; Vascular Endothelial Growth Factor Receptor-2

Topics: 8-Hydroxy-2'-Deoxyguanosine; Albuminuria; Amides; Antihypertensive Agents; Asian People; Blood Pressure; Chemokine CCL2; Creatinine; Deoxyguanosine; Diabetic Nephropathies; Female; Fumarates; Glomerular Filtration Rate; Humans; Interleukin-6; Male; Middle Aged; Oxidative Stress; Treatment Outcome

Advanced glycation end products (AGEs) mediate progressive tissue damage in diabetic nephropathy; however, their utility as a noninvasive reliable biomarker of progressive diabetic nephropathy remains to be determined. In this study, we investigated the temporal accumulation of the AGE carboxymethyllysine (CML) at various sites in a model of experimental diabetic nephropathy.. Diabetic rats were followed for 1, 4, 8, 16 and 32 weeks. Glomerular filtration rate and urinary albumin excretion were measured. CML was determined in the plasma, urine, renal cortical mitochondria and cytosol by an in-house ELISA. Gene expression of AGE receptors were quantified by real-time PCR and urinary excretion of 8-hydroxy-2'-deoxyguanosine (8-OHdG) was determined by EIA.. Four weeks after diabetes induction, urinary CML excretion was increased, which preceded the excretion of urinary albumin and continued to rise progressively until 32 weeks. Circulating, mitochondrial and cytosolic CML content and urinary excretion of 8-OHdG were increased 4 weeks after diabetes induction, but did not increase further with diabetes duration. Renal gene expression of AGE receptors was transiently upregulated at 1 week of diabetes, but this was not a sustained phenomenon.. The most informative marker of progressive renal damage linked to the AGE pathway in experimental diabetic nephropathy is urinary excretion of CML, which now warrants clinical investigation as a potential noninvasive sensitive marker of progressive diabetic nephropathy.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Albuminuria; Animals; Biomarkers; Cytosol; Deoxyguanosine; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 1; Diabetic Nephropathies; Gene Expression; Glomerular Filtration Rate; Glycation End Products, Advanced; Kidney Cortex; Lysine; Male; Mitochondria; Rats; Rats, Sprague-Dawley; Receptor for Advanced Glycation End Products; Receptors, Immunologic; RNA, Messenger; Streptozocin; Time Factors

Ezetimibe, an inhibitor of Niemann-Pick C1-like 1 protein, has been shown to reduce the intestinal absorption of cholesterol. We investigated whether it also has beneficial effects on metabolic disorder and/or renal insufficiency in patients with hypercholesterolemia.. Ezetimibe was administered to 38 Japanese patients with hypercholesterolemia to obtain appropriate low-density lipoprotein cholesterol (LDL-chol) levels. Age- and sex-matched patients with hypercholesterolemia (n=38) were the controls. We evaluated the effects of ezetimibe before and 4 to 8 weeks after ezetimibe treatment.. Ezetimibe significantly decreased LDL-chol levels and metabolic syndrome-related factors, including body weight, waist circumference, blood pressure; homeostasis model assessment insulin resistance (HOMA-IR), and urinary albumin excretion, were significantly reduced. In addition, it decreased the level of high-sensitivity C-reactive protein (hs-CRP), tumor necrosis factor (TNF)-alpha, the urinary excretion of 8-hydroxy-2'-deoxyguanosine, a parameter of oxidative stress, and increased the urinary excretion of nitrate and nitrite (NOx). In the controls we observed no such changes. Excepting the decrease in the serum TNF-alpha level, the effects of ezetimibe were not correlated with decreased LDL-chol levels.. Ezetimibe ameliorated the status of metabolic syndrome and microalbuminuria, reduced inflammation and oxidative stress, and increased nitric oxide bioavailability in a LDL-chol reduction-dependent and -independent manner.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Aged; Albuminuria; Anticholesteremic Agents; Azetidines; C-Reactive Protein; Case-Control Studies; Cholesterol, LDL; Deoxyguanosine; Ezetimibe; Female; Humans; Hypercholesterolemia; Male; Metabolic Diseases; Metabolic Syndrome; Middle Aged; Nitrates; Nitrites; Oxidative Stress; Tumor Necrosis Factor-alpha

Previous studies have demonstrated that AST-120 (Kremezin((R))), a well-known oral adsorbent, inhibits the progression of diabetic (DM) and non-DM chronic kidney disease along with a decrease in oxidative stress. This study was undertaken to investigate whether AST-120 could reduce oxidative stress and ameliorate the development of nephropathy in experimental DM rats with normal renal function.. Rats were injected with diluent (C, n = 16) or 65 mg/kg streptozotocin intraperitoneally (DM, n = 16), and eight rats from each group were treated with chow containing 5% AST-120. After 3 months, plasma advanced oxidation protein products (AOPP) and total malondialdehyde (MDA) levels, 24-h urinary albumin excretion, and urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) excretion were determined by ELISA. Glomerular endothelial nitric oxide synthase (eNOS), subunits of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (gp91phox, p47phox and p22phox), and fibronectin (FN) mRNA and protein expressions were determined by real-time PCR and western blot, respectively. In addition, dichlorodihydrofluorescein diacetate (DCF-DA) staining was performed to detect glomerular reactive oxygen species (ROS) production.. Compared to the C group, 24-h urinary albumin excretion was significantly higher in the DM group (P < 0.01), and AST-120 treatment significantly reduced albuminuria in DM rats (P < 0.05). Glomerular eNOS, gp91phox, p47phox and FN expression were significantly increased in DM rats compared to C rats, and these increases in DM glomeruli were significantly abrogated by AST-120 treatment (P < 0.05). The increases in plasma AOPP and MDA levels as well as renal oxidative stress in DM rats, assessed by DCF-DA staining and urinary 8-OHdG excretion rates, were also significantly attenuated by AST-120 treatment (P < 0.05).. In conclusion, the renoprotective effects of AST-120 in DM nephropathy seem to be associated with the amelioration of enhanced oxidative stress and FN expression under diabetic conditions.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Administration, Oral; Albuminuria; Animals; Carbon; Deoxyguanosine; Diabetic Nephropathies; Disease Models, Animal; Disease Progression; Fibronectins; Male; Malondialdehyde; NADPH Oxidases; Nitric Oxide Synthase Type III; Oxidative Stress; Oxides; Rats; Rats, Sprague-Dawley; Reactive Oxygen Species; Streptozocin

Proteinuria is not merely a marker of chronic nephropathies, but may also be involved in the progression to end-stage renal failure. We investigated the effect of angiotensin II type 1 receptor blockers (ARBs) on albumin-induced cell damage in human renal proximal tubular epithelial cells (RPTEC).. The N-acetyl-beta-D-glucosaminidase (NAG) and 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels in the medium after albumin treatment with ARBs were determined by commercially available kits. The levels of p22(phox) protein in RPTEC were measured using Western blotting after albumin treatment with ARBs. Angiotensin II concentrations in cell media and cell lysates were assayed with a commercially available kit.. Human albumin (0.1-10 mg/ml) dose-dependently increased NAG release and olmesartan or valsartan (10(-9)-10(-7) mol/l) showed a significant reduction on albumin (1 mg/ml)-induced NAG release in RPTEC. Albumin treatment (1 mg/ml) showed significant increases in p22(phox) protein levels in RPTEC and ARBs significantly decreased albumin-induced p22(phox) protein levels. Significant increases in 8-OHdG levels were observed in the albumin (1 mg/ml)-treated group and ARBs markedly reduced albumin-induced 8-OHdG levels in RPTEC. Human albumin dose-dependently increased angiotensin II concentrations in both cell media and lysates.. These observations suggest renal tubular cell-protective properties of ARBs related to decreased oxidative stress during proteinuria.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Acetylglucosaminidase; Albumins; Albuminuria; Angiotensin II; Angiotensin II Type 1 Receptor Blockers; Cells, Cultured; Deoxyguanosine; Dose-Response Relationship, Drug; Humans; Imidazoles; Kidney Tubules, Proximal; NADPH Oxidases; Oxidative Stress; Tetrazoles; Valine; Valsartan

It has been reported that urinary oxidative stress markers are higher in diabetic patients with proteinuria. We performed the present study to elucidate the relationship between urinary excretion of oxidative stress markers, albumin excretion, and histological changes, and to confirm the potential utility of oxidative stress markers for clinical treatment.. Diabetic db/db mice or nondiabetic db/m mice were administered candesartan (10 mg/kg/day) or hydralazine (50 mg/kg/day) for 18 weeks.. Thirty-week-old male db/db mice treated with control vehicle revealed elevated urinary excretion and immunohistological levels of 8-hydroxydeoxyguanosine in glomeruli when compared to db/m mice. Treatment with candesartan, but not hydralazine, reduced these values to levels in db/m mice. Increased mesangial expansion, urinary excretion of albumin and 8-isoprostane, and glomerular immunohistological levels of nitrotyrosine in db/db mice were also decreased markedly by candesartan but not hydralazine. Interestingly, correlations between levels of albumin and oxidative stress markers in urine were very high, even when groups undergoing long-term (44 weeks) treatment were included (correlation coefficient 0.767 with respect to 8-hydroxydeoxyguanosine, 0.888 with respect to 8-isoprostane).. It is anticipated that urinary concentrations of oxidative stress markers will be direct barometers of glomerulus-derived oxidative stress and glomerular injury in diabetic nephropathy.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Albuminuria; Angiotensin II Type 1 Receptor Blockers; Animals; Antihypertensive Agents; Benzimidazoles; Biomarkers; Biphenyl Compounds; Deoxyguanosine; Diabetes Mellitus; Diabetic Nephropathies; Dinoprost; Disease Models, Animal; Hydralazine; Kidney Glomerulus; Male; Mice; Mice, Inbred C57BL; Oxidative Stress; Tetrazoles; Treatment Outcome; Tyrosine

Serotonin (5-HT) is involved in vascular inflammation and atherosclerogenesis. Serum 5-HT concentrations are elevated in diabetes, and 5-HT is involved in diabetic vasculopathies. Sarpogrelate hydrochloride, a 5-HT2A receptor antagonist, has renoprotective effects, but its effect in diabetic nephropathy is not elucidated. The aim of this study was to examine the effects of sarpogrelate on endothelial dysfunction in rats with streptozotocin (STZ)-induced diabetes.. Rats with STZ-induced diabetes were either untreated or treated with sarpogrelate (30 mg/kg P.O.) for 8 weeks. At the end of the experiment, we measured urinary albumin excretion, serum adiponectin concentration and platelet-derived microparticles. Intraglomerular coagulation was detected by immunostaining for platelets. Production of renal reactive oxygen species (ROS) and nitric oxide (NO) was investigated by confocal laser microscopy and used as an index of glomerular endothelial dysfunction.. Diabetic nephropathy was associated with enhanced production of ROS and diminished bioavailable NO in the glomeruli. Treatment with sarpogrelate improved ROS/NO imbalance in glomeruli, suppressed platelet aggregation in glomeruli, reduced platelet-derived microparticles, increased serum adiponectin level and reduced the level of albuminuria, compared with non-treated diabetic rats.. Our results indicate that sarpogrelate improves endothelial function in rats with STZ-induced diabetes through a reduction of glomerular platelet activation and an increase in serum adiponectin concentrations and suggest that sarpogrelate is potentially useful for the treatment of diabetic nephropathy.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Adiponectin; Albuminuria; Animals; Blood Platelets; Deoxyguanosine; Diabetes Mellitus, Experimental; Diabetic Nephropathies; Endothelium, Vascular; Immunohistochemistry; Kidney Glomerulus; Male; Nitric Oxide; Nitric Oxide Synthase; Platelet Aggregation; Rats; Rats, Wistar; Reactive Oxygen Species; Receptor, Serotonin, 5-HT2A; Serotonin 5-HT2 Receptor Antagonists; Serotonin Antagonists; Succinates; Time Factors

To assess the therapeutic effect of losartan on type 2 diabetes mellitus (DM2) with gas chromatography (GC)-based metabonomics.. DM2 patients were dosed with losartan (100 mg/d) and urines were collected at week 8 and 12. The biochemical criteria (blood pressure, urinary albumen, urinary 8-hydroxy-2'-deoxyguanosine and blood creatinine) were analyzed. Urine samples were derivatived and analyzed by GC. Multivariate metabonomics analysis was performed after peak alignment.. After 8-12 weeks, losartan showed little curative effect and no remarked changes of biochemical criteria were observed. However, metabonomics analysis revealed that some biomarkers such as glucitol and inositol changed.. GC-based metabonomics analysis enables the rapid identification of metabolic differences and provides information concerning therapeutic effect of losartan.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Albuminuria; Biomarkers; Chromatography, Gas; Creatinine; Deoxyguanosine; Diabetes Mellitus; Diabetes Mellitus, Type 2; Drug Monitoring; Humans; Hypoglycemic Agents; Inositol; Losartan; Metabolome; Sorbitol

Oxidative stress may contribute to the pathogenesis of diabetic nephropathy (DN), although the detailed mechanism of reactive oxygen species (ROS) regulation is still unclear. This study examined the effect of high-salt diet on ROS production and expression of antioxidant enzymes in control and experimentally diabetic rats. Wistar fatty rats (WFR) as a type 2 diabetes mellitus model and Wistar lean rats (WLR) as a control were fed a normal-salt diet (NS) and high-salt diet (HS) from the age of 6 to 14 weeks. We then examined the blood pressure, urinary albumin excretion (UAE), and urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels. The expression of antioxidant enzymes including alpha-catalase (CAT), Cu-Zn superoxide dismutase (SOD), Mn SOD, and glutathione peroxidase (GPx) were analyzed in the glomeruli of the rats using Western blotting. The expression of NAD(P)H oxidase p47(phox) and NFkappaB p65 was evaluated using immunohistochemical staining. By 14 weeks of age, the WFR-HS group exhibited hypertension and markedly increased UAE. The level of 8-OHdG, a marker of oxidative damage, in the WFR-HS group was also higher than that in the WLR groups or WFR-NS group. The expression of alpha-CAT and Mn SOD proteins was significantly decreased in isolated glomeruli in the WFR-HS group. GPx and Cu-Zn SOD expression did not differ between the WFR and WLR groups. High expression of ROS and decreases in antioxidants were seen in the glomeruli of diabetic rats with hypertension, suggesting that oxidative stress may be involved in the development of DN.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Albuminuria; Animals; Blood Pressure; Blotting, Western; Body Weight; Deoxyguanosine; Diabetic Nephropathies; Disease Progression; Glucose Tolerance Test; Hypertension; Immunohistochemistry; Insulin; Kidney; Kidney Glomerulus; Male; NADPH Oxidases; Organ Size; Oxidative Stress; Rats; Rats, Inbred WKY; Rats, Zucker; Transcription Factor RelA

This study aimed to investigate the effect of the Rho-kinase inhibitor fasudil on the development of diabetic nephropathy and clarify a contribution of the Rho/Rho-kinase pathway to the pathogenesis of diabetic nephropathy. Diabetes was induced in male Sprague-Dawley rats with an intraperitoneal injection of streptozotocin. Animals were then divided into the following 4 groups; normal control rats, diabetic rats, diabetic rats administered fasudil orally and diabetic rats administered fluvastatin (3-hydroxy-methylglutaryl coenzyme A reductase inhibitor, statin) orally. After 1 month of treatment, neither fasudil nor statin had any influence on blood glucose or blood pressure in diabetic rats. While urinary excretion of albumin and 8-hydroxydeoxyguanosine (8-OHdG) was increased in diabetic rats, both of these increases were abolished by fasudil and statin. Rho activity was enhanced in the renal cortex of diabetic rats compared to normal controls, and this enhancement was abolished by statin treatment. Expression of transforming growth factor-beta (TGF-beta) and connective tissue growth factor (CTGF) mRNA was up-regulated in the renal cortex of diabetic rats, and this was abolished by fasudil as well as statin. Expression of NOX4 mRNA (catalytic subunit of NAD(P)H oxidase) was up-regulated in the renal cortex of diabetic rats, an effect which was also abolished by fasudil as well as statin. The present study demonstrates that the Rho/Rho-kinase pathway is involved in up-regulation of TGF-beta, CTGF and NAD(P)H oxidase in diabetic kidney. We conclude that suppression of the Rho/Rho-kinase pathway could be a new strategy for the treatment of diabetic nephropathy.

Topics: 1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; 8-Hydroxy-2'-Deoxyguanosine; Albuminuria; Animals; Blood Glucose; Blood Pressure; Cholesterol; Connective Tissue Growth Factor; Deoxyguanosine; Diabetes Mellitus, Experimental; Diabetic Nephropathies; Fatty Acids, Monounsaturated; Fluvastatin; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Immediate-Early Proteins; Indoles; Intercellular Signaling Peptides and Proteins; Intracellular Signaling Peptides and Proteins; Kidney Cortex; Male; NADPH Oxidase 4; NADPH Oxidases; Protein Kinase Inhibitors; Protein Serine-Threonine Kinases; Rats; Rats, Sprague-Dawley; rho-Associated Kinases; RNA, Messenger; Streptozocin; Transforming Growth Factor beta

Recent studies have uncovered various pleiotrophic effects of 3-hydroxy-3-methylglutaryl coenzyme A reductase-inhibiting drugs (statins). Several studies have identified a beneficial effect of statins on diabetic nephropathy; however, the molecular mechanisms are unclear. In this study, we show that statin ameliorates nephropathy in db/db mice, a rodent model of type 2 diabetes, via downregulation of NAD(P)H oxidase NOX4, which is a major source of oxidative stress in the kidney. Pitavastatin treatment for 2 weeks starting at 12 weeks of age significantly reduced albuminuria in the db/db mice concomitant with a reduction of urinary 8-hydroxy-2'-deoxyguanosine and 8-epi-prostaglandin F(2alpha). Immunohistochemical analysis found increased amounts of 8-hydroxy-2'-deoxyguanosine and NOX4 protein in the kidney of db/db mice. Quantitative reverse transcription-polymerase chain reaction also showed increased levels of NOX4 mRNA. Pitavastatin normalized all of these changes in the kidneys of diabetic animals. Additionally, 12-week treatment with the statin completely normalized the levels of transforming growth factor-beta1 and fibronectin mRNA as well as the mesangial expansion characteristic of diabetic nephropathy. Our study demonstrates that pitavastatin ameliorates diabetic nephropathy in db/db mice by minimizing oxidative stress by downregulating NOX4 expression. These findings may provide insight into the mechanisms of statin therapy in early stages of diabetic nephropathy.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Albuminuria; Animals; Blood Glucose; Body Weight; Cell Proliferation; Deoxyguanosine; Diabetes Mellitus, Type 2; Diabetic Nephropathies; Dinoprost; Disease Models, Animal; Down-Regulation; Fibronectins; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Lipids; Male; Mesangial Cells; Mice; NADPH Oxidase 4; NADPH Oxidases; Oxidative Stress; Quinolines; RNA, Messenger; Time Factors; Transforming Growth Factor beta1

Oxidative stress has been suggested to play an important role in the pathogenesis of diabetic nephropathy because it increases under diabetic conditions and is known to induce cellular dysfunction in a wide variety of cells. To protect cells against oxidative stress, cells possess defensive mechanisms such as intracellular antioxidants. Although it has been reported that central enzymes in the antioxidative defense mechanisms of the cell are induced under hyperglycemic conditions, the oxidative stress level remains high. On the other hand, there are endogenous inhibitors of antioxidants, such as thioredoxin interacting protein (Txnip). In the present study, the relationship between diabetic nephropathy and Txnip was investigated using streptozotocin (STZ)-induced diabetic mice. Eight-week-old male C57BL/6 mice were treated with either STZ or citrate vehicle. After 24 weeks of treatment, diabetic nephropathy and oxidative stress were assessed by biochemical analyses of urine and histological analyses of the kidneys. In addition, the expression of Type IV collagen alpha1 chain (Col4A1), Transforming growth factor-beta (TGF-beta), and Txnip were evaluated by real-time polymerase chain reaction. Albuminuria, renal hypertrophy, and expansion of the mesangial area, which are the hallmarks of diabetic nephropathy, were confirmed in the diabetic mice. The mRNA expression of COL4A1 and TGF-beta was dramatically increased in diabetic mice in comparison with the control mice. Moreover, associated with the increased renal expression of Txnip, diabetic conditions increased oxidative stress as determined by urinary excretion of 8-hydroxy-2'-deoxyguanosine and acrolein adduct, which are oxidative stress markers. Moreover, Txnip may be a therapeutic target in diabetic nephropathy.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Acrolein; Albuminuria; Animals; Biomarkers; Carrier Proteins; Collagen Type IV; Deoxyguanosine; Diabetic Nephropathies; Hypertrophy; Kidney; Male; Mice; Mice, Inbred C57BL; Oxidative Stress; RNA, Messenger; Streptozocin; Thioredoxins; Transforming Growth Factor beta

Glutathione S transferases (GSTs) are widely distributed enzymes found in highly varying amounts in tissues of the human body. The enzyme GST-pi in urine has been used as a marker of renal distal tubular cell damage. The present study was intended to evaluate urinary excretion of GST-pi and its relationship to other renal markers and to the status of oxidative stress in preterm neonates.. Levels of urinary GST-pi, N-acetyl-beta-glucosaminidase (a marker of proximal tubular damage), albumin (a marker of glomerular damage) and 8-hydroxy-2'-deoxyguanosine (a marker of oxidative stress) and serum creatinine were measured in preterm neonates at 1 and 4 weeks of age.. The results showed that urinary excretion of GST-pi is increased in preterm neonates compared with reported values for healthy adults. No significant relationship was detected between urinary GST-pi and other markers for renal function. Urinary GST-pi showed significantly positive correlation with urinary 8-hydroxy-2'-deoxyguanosine at 1 and 4 weeks. Sick neonates treated with supplemental oxygen and mechanical ventilation showed significantly higher levels of GST-pi as well as 8-hydroxy-2'-deoxyguanosine than clinically stable neonates did at 4 weeks.. These results indicate the potential effect of systemic oxidative stress on urinary excretion of GST-pi. Further studies are necessary to explore the effect of oxidative conditions on expression of GST-pi in distal tubules in the human kidney.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Acetylglucosaminidase; Albuminuria; Deoxyguanosine; Glutathione S-Transferase pi; Humans; Infant, Newborn; Infant, Premature

Oxidative stress is implicated as an important mechanism by which diabetes causes nephropathy. Astaxanthin, which is found as a common pigment in algae, fish, and birds, is a carotenoid with significant potential for antioxidative activity. In this study, we examined whether chronic administration of astaxanthin could prevent the progression of diabetic nephropathy induced by oxidative stress in mice. We used female db/db mice, a rodent model of type 2 diabetes, and their non-diabetic db/m littermates. The mice were divided into three groups as follows: non-diabetic db/m, diabetic db/db, and diabetic db/db treated with astaxanthin. Blood glucose level, body weight, urinary albumin, and urinary 8-hydroxydeoxyguanosine (8-OHdG) were measured during the experiments. Histological and 8-OHdG immunohistochemical studies were performed for 12 weeks from the beginning of treatment. After 12 weeks of treatment, the astaxanthin-treated group showed a lower level of blood glucose compared with the non-treated db/db group; however, both groups had a significantly high level compared with the db/m mice. The relative mesangial area calculated by the mesangial area/total glomerular area ratio was significantly ameliorated in the astaxanthin-treated group compared with the non-treated db/db group. The increases in urinary albumin and 8-OHdG at 12 weeks of treatment were significantly inhibited by chronic treatment with astaxanthin. The 8-OHdG immunoreactive cells in glomeruli of non-treated db/db mice were more numerous than in the astaxanthin-treated db/db mice. In this study, treatment with astaxanthin ameliorated the progression and acceleration of diabetic nephropathy in the rodent model of type 2 diabetes. The results suggested that the antioxidative activity of astaxanthin reduced the oxidative stress on the kidneys and prevented renal cell damage. In conclusion, administration of astaxanthin might be a novel approach for the prevention of diabetes nephropathy.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Albuminuria; Animals; beta Carotene; Deoxyguanosine; Diabetes Mellitus, Type 2; Diabetic Nephropathies; Disease Models, Animal; Female; Kidney; Mice; Mice, Mutant Strains; Reference Values; Regression Analysis; Tissue Distribution; Xanthophylls

To evaluate urinary 8-hydroxydeoxyguanosine (8-OHdG) as a marker for the progression of diabetic macroangiopathic complications.. The content of urinary 8-OHdG, common carotid intima-media thickness (IMT), the coronary heart disease (CHD) risk score, the severity of diabetic retinopathy, and urinary albumin excretion were examined in 96 patients with type 2 diabetes, including 32 patients who had been nominated for the Kumamoto Study [Shichiri M, et al. Diabetes Care 23 (Suppl 2):B21-B29, 2000]. In addition, the patients from the Kumamoto Study were further evaluated regarding the effect of intensive insulin therapy on urinary 8-OHdG excretion.. The urinary 8-OHdG:creatinine ratio (U8-OHdG) was 2.5-fold higher in patients with increased HbA(1c) than in those with normal HbA(1c) (P < 0.05). In addition, U8-OHdG was 2.3-fold higher in patients with increased IMT (P < 0.005). A similar result was observed between U8-OHdG and CHD risk score (P < 0.01). U8-OHdG was significantly higher in patients with simple retinopathy (P < 0.05) and those with advanced retinopathy (P < 0.01) than in patients without retinopathy. Similarly, U8-OHdG was significantly higher in patients with albuminuria (P < 0.01). Furthermore, in the Kumamoto Study, U8-OHdG was significantly lower in the multiple insulin injection therapy group compared with the conventional insulin injection therapy group (P < 0.01).. Hyperglycemia independently increases 8-OHdG in patients with type 2 diabetes. 8-OHdG is a useful biomarker of not only microvascular but also macrovascular complications in patients with type 2 diabetes.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Aged; Albuminuria; Biomarkers; Carotid Artery, Common; Creatinine; Deoxyguanosine; Diabetes Mellitus, Type 2; Diabetic Angiopathies; Diabetic Retinopathy; Drug Administration Schedule; Female; Humans; Insulin; Male; Middle Aged; Risk Factors; Tunica Intima; Tunica Media

Recently, much attention has focused on the role of oxidative stress in the various forms of tissue damage in patients with diabetes. The aim of this study was to examine the involvement of oxidative stress in the progression of kidney dysfunction and neuropathy in diabetes and to evaluate the potential usefulness of glutathione (GSH) in diabetes. We examined the effect that treatment of streptozotocin (STZ)-induced diabetic rats with GSH has on the renal and neural functions. Diabetic rats were treated with 1 g/100 g GSH as a dietary supplement. GSH significantly suppressed the diabetes-induced increase in urinary 8-hydroxy-2'-deoxyguanosine, one of the markers of oxidative stress. It also prevented the diabetes-induced increases in albumin and creatinine in urine. The diabetes-induced increase in the tail flick reaction time to thermal stimuli also was normalized by treatment with dietary GSH. In conclusion, GSH treatment can beneficially affect STZ-induced diabetic rats, with preservation of in vivo renal and neural function. This suggests a potential usefulness of dietary GSH treatment to reduce diabetic complications.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Albuminuria; Animals; Blood Glucose; Creatinine; Deoxyguanosine; Diabetes Mellitus, Experimental; Diabetic Nephropathies; Diabetic Neuropathies; Dietary Supplements; Disease Models, Animal; Glutathione; Hot Temperature; Male; Oxidation-Reduction; Oxidative Stress; Rats; Rats, Wistar; Streptozocin

It has been reported that advanced glycosylation end products (AGEs) play an important role in the development of diabetic complications. To evaluate the relationship between serum AGEs and diabetic nephropathy, we measured serum AGE levels in diabetic patients with normoalbuminuria (N), microalbuminuria (M), overt proteinuria (O), and hemodialysis (HD), non diabetic patients with nephropathy, and age-matched control subjects using the enzyme-linked immunosorbent assay (ELISA). Urine AGE levels were also measured in these subjects except group HD. Serum AGE levels in diabetic patients were not significantly higher than those in the normal subjects. When we compared serum AGE levels among various stages of diabetic nephropathy, groups O and HD had significantly higher serum AGE levels than the other groups. Serum AGE levels in group HD were almost 6-fold higher than those in groups N and M. In contrast, there were no significant differences in urinary AGE levels among any diabetic groups. As for the variables that determine serum AGE levels in diabetic patients, there was no significant correlation between serum AGEs and fasting blood glucose, hemoglobin A1c (HbA1c), or duration of diabetes. In contrast, serum AGEs showed a strong correlation with serum creatinine and an inverse correlation with creatinine clearance. To evaluate the relationship between serum AGEs and oxidative stress in diabetic nephropathy, urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) and serum malondialdehyde (MDA), which are biological markers of total oxidative stress in vivo, were also examined. Both urinary 8-OHdG and serum MDA levels were significantly higher in diabetic patients with proteinuria versus those without proteinuria. However, there was no significant correlation between serum AGEs and urinary 8-OHdG or serum MDA levels in diabetic patients. These results suggest that the accumulation of serum AGEs in diabetic nephropathy may be mainly due to decreased removal in the kidney rather than increased production by high glucose levels or oxidative stress.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Albuminuria; Deoxyguanosine; Diabetes Mellitus; Diabetic Nephropathies; Female; Glycation End Products, Advanced; Humans; Kidney Diseases; Kidney Failure, Chronic; Male; Malondialdehyde; Middle Aged; Oxidative Stress; Proteinuria; Renal Dialysis

8-Hydroxydeoxyguanosine (8-OHdG), an oxygen radical induced modification of purine residue in DNA, was measured in the liver, pancreas, and kidney of streptozotocin-induced diabetic rats (STZR) exhibiting microalbuminuria. At 4 weeks after the injection of streptozotocin (50 mg/kg, i.v.), the rate of urinary albumin excretion was 0.5 +/- 0.1 and 2.0 +/- 0.2 mg/24 h in age-matched control rats (CR) and STZR, respectively. Compared to CR, STZR also showed a significantly increased level of 8-OHdG in the kidney but not the liver and pancreas. Amounts of 8-OHdG/10(5) dG for CR and STZR were 3.4 +/- 0.3 and 5.1 +/- 0.2 for renal cortices, and 4.1 +/- 0.2 and 20.0 +/- 3.7 for renal papillae. Daily injection of insulin (2 U, SC) starting on the third day after streptozotocin treatment significantly reduced both urinary albumin excretion and papillary 8-OHdG formation, which suggests that these are associated with the diabetic state induced by streptozotocin rather than a direct nephrotoxic effect of the drug. This study suggests that formation of 8-OHdG and, therefore, oxidative damage are closely related in the process of diabetic nephropathy.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Albuminuria; Animals; Deoxyguanosine; Diabetes Mellitus, Experimental; Diabetic Nephropathies; DNA Damage; Free Radicals; Kidney Cortex; Kidney Medulla; Liver; Male; Organ Specificity; Pancreas; Rats; Rats, Sprague-Dawley; Reference Values