In vivo formation of 8-iso-prostaglandin f2alpha and platelet activation in diabetes mellitus: effects of improved metabolic control and vitamin E supplementation

BACKGROUND: Diabetes mellitus (DM) is associated with enhanced lipid peroxidation and persistent platelet activation. We tested the hypothesis that the in vivo formation of the F2-isoprostane 8-iso-prostaglandin (PG)F2alpha, a bioactive product of arachidonic acid peroxidation, is enhanced in DM and contributes to platelet activation. METHODS AND RESULTS: Urine samples were obtained from 85 diabetic patients and 85 age- and sex-matched healthy subjects for measurement of immunoreactive 8-iso-PGF2alpha and 11-dehydro-thromboxane B2 (TXM), an in vivo index of platelet activation. Sixty-two had non-insulin-dependent (NID)DM, and 23 had insulin-dependent (ID) DM. Vitamin E supplementation, metabolic control, and cyclooxygenase inhibitors were used to investigate the mechanisms of formation of 8-iso-PGF2alpha in this setting. Urinary 8-iso-PGF2alpha excretion was significantly higher (P=0.0001) in NIDDM patients (419+/-208 pg/mg creatinine; range 160 to 1014) than in age-matched control subjects (208+/-92; 41 to 433). Urinary 8-iso-PGF2alpha was linearly correlated with blood glucose and urinary TXM. 8-iso-PGF2alpha excretion was also significantly (P=0. 0001) higher in IDDM patients (400+/-146; 183 to 702) than in control subjects (197+/-69; 95 to 353). Vitamin E supplementation (600 mg/d for 14 days) was associated with a statistically significant reduction in both urinary 8-iso-PGF2alpha (by 37%) and TXM (by 43%) in 10 NIDDM patients. Improved metabolic control was associated with a significant (P=0.0001) reduction in 8-iso-PGF2alpha and TXM excretion by 32% and 41%, respectively, in 21 NIDDM patients. 8-iso-PGF2alpha was unchanged after 2-week dosing with aspirin and indobufen despite profound suppression of TXM excretion. CONCLUSIONS: We conclude that DM is associated with increased formation of F2-isoprostanes, as a correlate of impaired glycemic control and enhanced lipid peroxidation. This may provide an important biochemical link between impaired glycemic control and persistent platelet activation. These results provide a rationale for dose-finding studies of antioxidant treatment in diabetes.     

Oxidative stress and cardiovascular complications in diabetes: isoprostanes as new markers on an old paradigm

Long-term vascular complications still represent the main cause of morbidity and mortality in diabetic patients. Although randomized long-term clinical studies comparing the effects of conventional and intensive therapy have demonstrated a clear link between hyperglycemia and the development of complications of diabetes, they have not defined the mechanism through which excess glucose results in tissue damage. Evidence has accumulated indicating that oxidative stress may play a key role in the etiology of diabetic complications. Isoprostanes are emerging as a new class of biologically active products of arachidonic acid metabolism of potential relevance to human vascular disease. Their formation in vivo seems to reflect primarily, if not exclusively, a nonenzymatic process of lipid peroxidation. Enhanced urinary excretion of 8-iso-PGF(2alpha) has been described in association with both type 1 and type 2 diabetes mellitus, and correlates with impaired glycemic control. Besides providing a likely noninvasive index of lipid peroxidation in this setting, measurements of specific F(2) isoprostanes in urine may provide a sensitive biochemical end point for dose-finding studies of natural and synthetic inhibitors of lipid peroxidation. Although the biological effects of 8-iso-PGF(2alpha) in vitro suggest that it and other isoeicosanoids may modulate the functional consequences of lipid peroxidation in diabetes, evidence that this is likely in vivo remains inadequate at this time.     

ADMA and oxidative stress may relate to the progression of renal disease: rationale and design of the VIVALDI study

The renin angiotensin system has been shown to be involved in the pathogenesis of vascular and renal sequelae of diabetes mellitus. In type 2 diabetes mellitus, angiotensin receptor blockers have been shown to exert clinical benefit by reducing the progression of diabetic nephropathy. They also improve endothelium-mediated vascular function. The latter effect is partly due to the reduction of angiotensin II-associated oxidative stress. Moreover, small clinical studies have shown that treatment with angiotensin receptor blockers also reduces the circulating levels of asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide (NO) synthase. In the VIVALDI trial, the ability of the angiotensin receptor blocker telmisartan to reduce the progression of diabetic nephropathy (associated with proteinuria) in comparison with valsartan in more than 800 patients with type 2 diabetes during 1 year of treatment is being studied. In order to gain more detailed insight into the potential pathomechanisms associated with this effect, further end-points have been defined. Among these are the circulating levels of ADMA and the urinary excretion rate of 8-iso-prostaglandin F2alpha (8-iso-PGF2alpha). The former is an endogenous inhibitor of NO-mediated vascular function(s) and a prospectively determined marker of major cardiovascular events and mortality; the latter is a lipid peroxidation product resulting from the nonenzymatic peroxidation of arachidonic acid, which exerts detrimental vascular effects similar to those of thromboxane A2. Urinary 8-iso-PGF2alpha has been shown in clinical studies to be an independent marker of cardiovascular disease. Highlighting the effects of telmisartan on ADMA and 8-iso-PGF levels in such a large cohort of diabetic patients will enhance our understanding of the roles of dysfunctional NO metabolism and redox mechanisms in the pathogenesis of end-organ damage and its prevention by pharmacotherapy with angiotensin receptor blockers.     

Increased formation of 8-iso-prostaglandin F(2alpha) is associated with altered bone metabolism and lower bone mass in hypercholesterolaemic subjects

OBJECTIVES: To investigate the relationship of 8-iso-prostaglandin (PG) F(2alpha) levels, a reliable marker of in vivo oxidative stress and lipid peroxidation, with bone mineral density (BMD), bone turnover markers, osteoprotegerin (OPG) and receptor activator of nuclear factor-kappa B ligand (RANKL) in hypercholesterolaemia. DESIGN: Cross-sectional study. SETTING: University hospital centre. METHODS: Serum 8-iso-PGF(2alpha) levels were measured in 173 hypercholesterolaemic subjects and in 152 age- and sex-matched normocholesterolaemic controls. Femoral neck and lumbar spine BMD, serum bone-specific alkaline phosphatase (BAP), osteocalcin (OC), OPG and RANKL levels, as well as urinary levels of C-terminal telopeptides of type I collagen (CTX-I), were also assessed. RESULTS: Hypercholesterolaemic subjects showed higher (P < 0.0001) serum 8-iso-PGF(2alpha) levels than controls. They also had decreased (P < 0.0001) femoral neck and lumbar spine BMD, and lower (P < 0.0001) serum BAP and OC levels. No significant differences between hypercholesterolaemic and control subjects were found when comparing urinary CTX-I levels, or serum OPG and RANKL levels. In multivariate linear regression analysis, serum 8-iso-PGF(2alpha) was the only negative predictor for femoral neck BMD and serum BAP and OC levels in hypercholesterolaemic subjects. No significant correlation (all P > 0.25) was present between serum 8-iso-PGF(2alpha) levels and urinary CTX-I levels, or serum OPG and RANKL levels, in hypercholesterolaemic subjects. CONCLUSIONS: We found an association between increased serum 8-iso-PGF(2alpha) levels and lower bone mass and reduced serum BAP and OC concentrations in hypercholesterolaemic subjects. These results would suggest a possible role for oxidative stress in the development of lower bone mass in hypercholesterolaemia.     

Aldosterone blockade attenuates urinary monocyte chemoattractant protein-1 and oxidative stress in patients with type 2 diabetes complicated by diabetic nephropathy

CONTEXT: Aldosterone causes organic impairment by enhancement of oxidative stress and subsequent induction of proinflammatory cytokines and chemokines. OBJECTIVE: This study was designed to investigate the effect of spironolactone, an aldosterone blocker, on oxidative stress and the level of urinary monocyte chemoattractant protein (MCP)-1, a cysteine-cysteine chemokine that may contribute to progression of various nephropathies in type 2 diabetic patients with diabetic nephropathy. DESIGN, SETTING, PATIENTS AND OTHER PARTICIPANTS, AND INTERVENTION: The patients were randomly assigned to two groups in which they received either spironolactone (50 mg/d; n = 23) or amlodipine (2.5 mg/d; n = 14). MAIN OUTCOME MEASURES: Urinary 8-iso-prostaglandin (PG) F2alpha (a marker of oxidative stress), urinary MCP-1, and urinary albumin excretion (UAE) were measured at the start of administration (0 months) and after 3 months in each group. Baseline levels of these variables were also measured in 25 age-matched healthy subjects. RESULTS: There were significant positive correlations between log(10)-transformed (log) 8-iso-PGF2alpha and log MCP-1 levels in control and diabetic subjects and all subjects combined, but no correlations between log UAE and log 8-iso-PGF2alpha or log MCP-1 were found in any group. Significant decreases in 8-iso-PGF2alpha, MCP-1, and UAE were observed with spironolactone (P = 0.0001, P = 0.0041, and P = 0.0037, respectively), and systolic blood pressure significantly decreased after both spironolactone and amlodipine therapy (P = 0.00011 and P = 0.0051, respectively). CONCLUSIONS: Our data suggest that urinary MCP-1 is correlated with oxidative stress as measured by urinary 8-iso-PGF2alpha and that spironolactone can decrease urinary MCP-1 and oxidative stress.     

Decreased in vivo oxidative stress and decreased platelet activation following metformin treatment in newly diagnosed type 2 diabetic subjects

BACKGROUND: In type 2 diabetes, metformin reduces cardiovascular risk beyond the effect of glycaemic control. Since oxidative stress and the consequent enhanced platelet activation contribute to accelerated atherosclerosis in diabetes, we hypothesized that metformin could reduce oxidative stress in this condition. METHODS: We randomized 26 newly diagnosed type 2 diabetic subjects to assume either metformin (M, n = 13) or gliclazide (G, n = 13) for 12 weeks. Drugs were titrated as needed to achieve good glycaemic control. Before and after treatment, we determined blood glucose, insulin, HbA(1c), vitamin A and E levels and 8-iso-PGF(2alpha) and 11-dehydro-thromboxane B(2) urinary excretion, an in vivo oxidative stress and a thromboxane-dependent platelet activation marker, respectively. RESULTS: Notwithstanding a comparable improvement in metabolic control, 8-iso-PGF(2alpha) (M from 708 +/- 32 to 589 +/- 45 pg/mg cr, p < 0.001; G from 646 +/- 80 to 665 +/- 79, pg/mg cr, p = ns) and 11-dehydro-thromboxane B(2) (M from 2190 +/- 196 to 1753 +/- 150 pg/mg cr, p < 0.05; G from 2048 +/- 202 to 1923 +/- 223, pg/mg cr, p = ns) urinary excretion decreased after metformin but not after gliclazide treatment. After metformin, vitamin A and E levels significantly increased while they remained unchanged after gliclazide. CONCLUSIONS: These data suggest that metformin could improve oxidative stress, preserve antioxidant function and restrain platelet activation in type 2 diabetes.     

膳食抗氧化营养素对糖尿病患者氧化应激和血糖控制的影响

目的:探讨糖尿病(DM)患者日常饮食中抗氧化营养素和体内氧化应激水平对其血糖控制的影响,为临床合理饮食指导提供依据。方法:收集本院内分泌科住院DM患者49例,根据国内判断DM患者血糖控制与否的糖化血红蛋白(HbA1c)标准,将患者分为血糖控制良好组(G组)和控制不佳组(P组),调查其膳食中抗氧化营养素锌(Zn)、硒(Se)、维生素(Vit)A、VitC和VitE摄入量,检测患者血清HbA1c、抗氧化微营养素及氧化应激标志物8-异前列腺素F2α(8-iso-PGF2α)。比较2组患者膳食抗氧化营养素摄入量,及其与血清抗氧化营养素水平、氧化应激水平和血糖控制间的关系。结果:所有患者中仅G组有1例患者5种膳食抗氧化营养素摄入量全部达到参考摄入量,其余患者均存在不同程度的摄入不足。其中抗氧化营养素摄入不足种类≥3种者达34例(69%)。P组每日VitC摄入量未达参考摄入量的患者比例显著高于G组(86%比57%,P=0.025),2型DM(T2DM)显著高于1型DM患者(83%比58%,P=0.049)。P组患者血清8-iso-PGF2α水平显著高于G组(P=0.034),T2DM患者中P组亦高于G组(P=0.028)。所有49例患者的血清8-iso-PGF2α与HbA1c水平呈显著正相关(r=0.386,P=0.006),在T2DM患者中亦呈正相关(r=0.446,P=0.013)。结论:多数DM患者的膳食抗氧化营养素摄入不足,更多见于血糖控制不佳者和T2DM患者。     

alpha-Tocopherol levels in plasma in new-onset, insulin-dependent diabetes mellitus

BACKGROUND: Diabetic complications have been related to increased oxidative stress. Plasma antioxidant levels may be affected by hyperglycemia-induced oxidative stress as well as by insulin therapy. We evaluated the immediate effect of insulin treatment and improved metabolic control on the important antioxidant alpha-tocopherol plasma (vitamin E) levels in new-onset, insulin-dependent diabetes mellitus. METHODS: The study was performed in 15 consecutive patients, aged 20-67 years, with new-onset diabetes mellitus requiring acute insulin treatment. Plasma alpha-tocopherol levels were measured before the start of intensive insulin treatment and monthly for 6 months thereafter. Simultaneously, we studied plasma malondialdehyde (MDA) as a reflection of lipid peroxidation. In addition, comparisons were made to a nondiabetic reference group. RESULTS: Baseline alpha-tocopherol levels did not differ from those in nondiabetic subjects. alpha-Tocopherol decreased significantly, from 33.5+/-12.1 mumol/l before treatment to 28.11+/-6.85 mumol/l (-16%) after 1 month of insulin therapy (p<0.04) to 26.6+/-7.03 mumol/l (-20%) after 3 months of insulin therapy (p<0.02). This trend did not change after adjusting for variations in cholesterol levels. After 6 months, alpha-tocopherol was no longer decreased compared to baseline levels (29.6+/-7.4 mumol/l). MDA concentrations at baseline were significantly higher in the diabetic patients (3.79+/-2.91 mumol/l) than in the nondiabetic subjects (1.57+/-0.21 mumol/l, p=0.006). MDA concentrations decreased significantly following the start of insulin treatment. CONCLUSIONS: Patients with new-onset, insulin-dependent diabetes mellitus have alpha-tocopherol levels that are similar to those in normal subjects. Insulin treatment and/or improved metabolic control cause a significant decrease in alpha-tocopherol levels during the first months.     

8-iso-prostaglandin F2alpha as a useful clinical biomarker of oxidative stress in ESRD patients

BACKGROUND/AIMS: Chronic renal failure is associated with elevated indices of oxidative stress. We tested the hypothesis that the in vivo formation of the F(2)-isoprostane (8-iso-prostaglandin PGF(2alpha)), a bioactive product of arachidonic acid peroxidation, is enhanced in end-stage renal disease (ESRD) patients receiving hemodialysis (HD) and continuous ambulatory peritoneal dialysis (CAPD). METHODS: Plasma samples were obtained from 35 HD patients, 30 CAPD patients and 30 age- and sex-matched healthy subjects for measurement of immunoreactive 8-iso-PGF(2alpha). RESULTS: Plasma 8-iso-PGF(2alpha) levels were significantly higher (p < 0.001) in HD and CAPD patients (346.3 +/- 132.4 pg/ml; range 49.8-870) than in age-matched control subjects (150.9 +/- 61.6 pg/ml; range 33.5-235). In addition, we also found that 8-iso-PGF(2alpha) concentration was significantly (p = 0.007) higher in HD patients (389.8 +/- 148.3 pg/ml) than in CAPD patients (254.3 +/- 76.6 pg/ml). Plasma 8-iso-PGF(2alpha) concentration was linearly correlated with serum haptoglobin, C-reactive protein (CRP) and plasma MDA (r = 0.58, p = 0.003; r = 0.29, p < 0.05 and r = 0.38, p < 0.05 respectively). On the other hand, plasma 8-iso-PGF(2alpha) levels were inversely associated with serum albumin and total cholesterol (r = -0.31 and r = -0.28, respectively; p < 0.05). CONCLUSIONS: We conclude that ESRD on both HD and CAPD is associated with increased formation of F(2)-isoprostanes, a correlate of enhanced lipid peroxidation. We also found that plasma 8-iso-PGF(2alpha) was casually related to some acute phase reactant proteins such as serum CRP, albumin and haptoglobin. This may provide an important biochemical link between lipid peroxidation, inflammation and accelerated atherosclerosis in the uremic milieu.     

The oxygen stress index and levels of circulating interleukin-10 and interleukin-6 in patients with chronic heart failure

OBJECTIVES: We sought to study circulating levels of pro- and anti-inflammatory cytokines together with the oxygen stress index in patients with chronic heart failure (CHF). BACKGROUND: Patients with CHF exhibit elevated levels of inflammatory and anti-inflammatory cytokines but the relative level of these cytokines with the oxygen stress index have not been reported. METHODS: Twenty-two patients with CHF and 10 control subjects were studied. Plasma levels of IL-6 and IL-10 were determined and the oxygen stress index was evaluated by urine 8-iso-PGF2alpha estimations. RESULTS: Plasma levels of IL-6 and IL-10 in CHF patients were significantly higher than those observed in the control subjects. Patients with more advanced disease (higher NYHA class) showed higher concentrations of IL-10 and IL-6 than those with less serious disease. 8-iso-PGF2alpha urine concentration (and therefore the oxygen stress index) was significantly higher in patients with CHF in comparison with control subjects. IL-6 plasma levels, but not IL-10 concentrations, correlated significantly with 8-iso-PGF2alpha levels in urine. CONCLUSIONS: Inflammatory and anti-inflammatory cytokine levels, as well as the oxidative stress index, are increased in patients with chronic heart failure. Inflammatory cytokine IL-6, but not anti-inflammatory cytokine Il-10, levels correlated significantly with the oxygen stress index.     

糖尿病对骨密度及相关激素的影响

目的 观察DM患者骨密度（bone mineral density,BMD)及其相关激素的改变，并探讨其发生机制。方法 采用双能（线吸收法测量2型DM患者68例、1型DM患者54例和健康人62例的BMD，放免法测定血清骨钙素、降钙素和25羟维生素D3，免疫放射法测定血清完整甲状旁腺素及I型胶原羧基末段前肽。结果 ①两组DM患者全血HbA1c水平均显著高于对照组（P＜0．01），血清骨钙素水平显著低于对照组（P＜0．01）；②2型DM组BMI、大转子BMD显著高于对照组和1型DM组（BMI，P＜0．01；BMD，P＜0．05）；1型DM组股骨颈BMD低于对照组和2型DM组（P＜0．05），经BMI纠正后，1型DM组股骨颈BMD仍低于对照组（P＜0．05）；③1型DM组各位点BMD与血清I型胶原羧基末段前肽水平呈负相关（P＜0．05），2型DM组腰椎和大转子BMD与全血HbA1c水平呈负相关（P＜0．05）。结论 与健康人群相比，1型DM患者BMD明显降低，2型DM患者BMD明显增高，但经BMI纠正后，这种差异性消失；骨转化降低以及糖尿病代谢紊乱可能参与了糖尿病骨质疏松的发生。     

The effect of short- versus long-term administration of alpha tocopherol on the survival of random flaps in experimental diabetes mellitus

The effects of short- versus long-term alpha tocopherol administration on oxidative stress and survival of dorsal random flaps were studied in diabetic rats. Seven groups, with 20 rats in each, were constructed: (1) control, (2) noncontrolled diabetes, (3) noncontrolled diabetes+short-term alpha tocopherol, (4) noncontrolled diabetes+long-term alpha tocopherol, (5) insulin treatment, (6) insulin+short-term alpha tocopherol, and (7) insulin+long-term alpha tocopherol. After 3 months of diabetes, dorsal McFarlane flaps were raised. Flap viability and free-radical measurements with histopathological examination were investigated. Mean flap survival in Groups I to VII were 84.0+/-2.2%, 55.0+/-2.4%, 57.0+/-2.5%, 57.8+/-3.7%, 64.1+/-4.1%, 70.0+/-4.9%, and 77.0+/-6.6%, respectively. Free-radical concentration, as assessed with luminol- and lucigenin-enhanced chemiluminiscence, was inversely correlated with flap survival. The results for viability and free-radical concentrations were significant between Groups 1, 2, 5, 6, and 7. Random flaps in diabetic animals showed significantly greater necrosis compared with controls. Among the diabetic animals, group receiving combination of insulin and long-term alpha tocopherol treatment had the greatest flap viability and least tissue free-radical concentration. Histopathological studies showed a hyalinization of arterioles in diabetics with long-term alpha tocopherol treatment protecting the vessel wall. In conclusion, random flaps in experimental diabetes mellitus show greater tissue oxidative stress and necrosis, which is only partially corrected with insulin treatment. Long-term antioxidant supplementation as an adjunct to insulin further lowers the oxidative stress, protects vessel structure and function, and therefore increases flap survival.     

DNA damage and plasma antioxidant indices in Bangladeshi type 2 diabetic patients

Background and aimDiabetes mellitus is a complex metabolic disorder characterized by a disturbance in glucose metabolism. Recent evidence suggests that increased oxidative stress as well as alteration of antioxidant capacity may be related to the complications seen in patients with type 2 diabetes. The aim of this study was to measure serum antioxidant status in type 2 diabetic patients and to assess its relationship with oxidative DNA damage.MethodsA total of 57 subjects were included in this study. Of these, 32 were type 2 diabetic patients and 25 were non-diabetic subjects. Comet assay was used to quantify the level of DNA damage in lymphocytes. Spectrophotometric methods were used to assess serum levels of malondialdehyde (MDA) and protein carbonyl, and serum activity of superoxide dismutase (SOD) and the protein thiol (P-SH) group.ResultsA significant increase in mean comet tail DNA, indicating DNA damage, was observed in diabetic patients compared with controls. Diabetic patients had significantly higher levels of MDA and protein carbonyl in parallel with significant decreases in levels of SOD and the P-SH group compared with controls. Serum SOD was also inversely correlated with the increase in comet tail DNA.ConclusionThese results indicate the presence of significant lipid peroxidation, protein oxidation and oxidative DNA damage in patients with diabetes. Perturbation of glucose homoeostasis was associated with an increase in oxidants and a concomitant decrease of antioxidant enzymes in the type 2 diabetic patients’ blood. The present study suggests that the status of oxidant–antioxidant imbalance may be one of the mechanisms leading to the DNA damage detected in the lymphocytes of type 2 diabetic patients.     

2型糖尿病患者糖皮质激素变化的临床研究

目的　探讨 2型糖尿病患者糖皮质激素分泌变化的规律及其临床意义。方法　测定 2 2名健康人 (对照组 )和 6 3例 2型糖尿病患者 (其中 39例 2型糖尿病无微血管病变、2 4例 2型糖尿病并微血管病变 )的血皮质醇 (F) ( 8Am、4Pm )、2 4h尿游离皮质醇 (UFC)及血糖 (FBG、2hPG)、HbA1c、TC和TG。结果　 2型糖尿病组的血F( 8Am、4Pm)及 2 4hUFC与对照组比较 ,差异有显著性 (P <0 .0 5 )。糖尿病有微血管病变组的 2 4hUFC的排量高于无微血管病变组 (P <0 .0 5 )。糖尿病组 2 4hUFC与HbA1c呈正相关 (r =0 .2 76 ,P <0 .0 5 ) ,与病程呈正相关 (r =0 .72 4,P <0 .0 1) ,与 2 4h尿微量白蛋白 (UAP)呈正相关 (r =0 .486 ,P <0 .0 1) ,与TG呈正相关 (r= 0 .42 1,P <0 .0 1)。结论　 2型糖尿病患者糖皮质激素水平增高 ,加重了糖代谢和脂代谢紊乱 ,使糖尿病患者的病情恶化 ,最终促使糖尿病并发症的发生。     

Lipid peroxidation,antioxidants, lipid profile,and HbA1c in diabetic patients

Diabetes mellitus is characterized by hyperglycemia together with biochemical changes in glucose, lipid profile, lipid peroxidation, and antioxidants status. This study aims to assess lipid profile, lipid peroxidation, antioxidants, and glycated hemoglobin (HbA1c) in type 1 and type 2 diabetic subjects. Type 1 and type 2 diabetic patients were selected from the subjects attending OPD in Nepalgunj Medical College, Nepal, for medical checkup. Fasting blood sugar (FBS), lipid profile, lipid peroxidation (malondialdehyde), and antioxidants status (reduced glutathione and vitamin E) were estimated in both groups and were compared with healthy controls. Low-density lipoprotein (LDL)/high-density lipoprotein (HDL) ratio was calculated to assess the cardiovascular risk factors. When type 1 diabetic patients were compared with type 2 diabetic patients, it showed statistically significant increase in the levels of HbA1c, triglycerides (TGs), and high-density lipoprotein cholesterol (HDL-C), whereas statistically significant decreased level was found in malondialdehyde (MDA). FBS, total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), reduced glutathione (GSH), vitamin E, and HDL/LDL ratio were not significant. Early diagnosis of dyslipidemia and oxidative stress can be used as a preventive measure for the development of microvascular and macrovascular complications in type 1 and type 2 diabetes mellitus.     

Relation of C-reactive protein to oxidative stress and to endothelial activation in essential hypertension

BACKGROUND: C-reactive protein (CRP) predicts cardiovascular outcome. Oxidative stress is considered to be involved in endothelial alteration. We hypothesized that in essential hypertension (EH), oxidative stress, as measured by 8-iso-prostaglandin-F(2alpha) (8-iso-PGF(2alpha)), should be associated with increased CRP and endothelial activation, as evaluated by soluble intercellular adhesion molecule-1 (ICAM-1) and vascular adhesion molecule-1 (VCAM-1) plasma levels. METHODS: In 83 subjects with mild EH and in 50 healthy control subjects we measured, in basal conditions, plasma levels of hs-CRP, 8-iso-PGF(2alpha), ICAM-1 and VCAM-1, and tumor necrosis factor-alpha (TNF-alpha). RESULTS: Subjects with EH had higher levels of 8-iso-PGF(2alpha) (P < .0001), CRP (P < .001), ICAM-1 and VCAM-1 (P < .001), and TNF-alpha (P < .001) than did control subjects. We divided successively EH according to CRP values (<1, 1-3, >3 mg/L), and we observed increasing and significantly different levels of the endothelial parameters and of TNF-alpha along with increasing CRP. Linear analysis of correlation pointed out significant correlation of CRP with 8-iso-PGF(2alpha) (r = 0.730, P < .001), ICAM-1 and VCAM-1 (r = 0.642 and 0.468, P < .001 respectively), and TNF-alpha (r = 0.609, P < .001). Multiple regression analysis using CRP as a dependent variable confirmed the relationship of CRP with systolic blood pressure (beta 0.216, P = 0.039) and with 8-iso-PGF(2alpha) (beta 0.602, P = .0001). CONCLUSIONS: Our data demonstrate that in EH, inflammatory molecules such as CRP and TNF-alpha are increased and related to both oxidative stress and endothelial activation.     

Oxidative markers in diabetic ketoacidosis

Oxidative stress has been implicated in the pathogenesis of the chronic complications of diabetes mellitus but little is known in diabetic ketoacidosis (DKA). The aim of this work was to determine whether lipid peroxidation, as assessed by measuring malondialdehyde (MDA, a prooxidant) and antioxidant status (TAS, an index of antioxidant defenses), is modified in DKA, and also whether any observed abnormalities were related to metabolic disturbances. METHODS: four groups of patients were studied, comprising 19 patients with DKA, massive ketonuria and plasma standard bicarbonate levels below 16 mmol/l (group 1); 20 patients with poorly controlled diabetes, glycated hemoglobin (HbA1c) above 8% and plasma bicarbonate levels above 16 mmol/l (group 2); 11 patients with well-controlled diabetes and HbA1c below 8% (group 3); and 10 non-diabetic, non-obese control subjects (group 4). Metabolic parameters, MDA levels and TAS were assessed in the plasma of the four groups of subjects. RESULTS: mean plasma MDA and TAS values were significantly different among the four groups (respectively p < 0.001 and p < 0.01). Mean plasma MDA value was significantly higher in group 1 than in group 3 (p < 0.02) and group 4 (p < 0.001) but was not different from that in group 2. Mean plasma MDA value in group 2 was significantly lower than that in group 4 (p = 0.002). Mean plasma TAS value in group 1 was significantly lower than in groups 3 (p < 0.002) and 4 (p < 0.05). Mean plasma TAS value was significantly lower in group 2 than in group 4 (p<0.05). Plasma MDA values in the diabetic patients (groups 1+2+3) were not related to any clinical characteristics (BMI, age, duration of the disease) or metabolic parameters (glycemia, HbA1c bicarbonates, blood urea nitrogen, phosphatemia, lipids), while plasma TAS values correlated negatively with glycemia, osmolality and HbA1c. A significant relationship was also found between TAS and HbA1c in group 1 (p < 0.05) and between MDA and HbA1c in group 3 (p < 0.05). Correlations were also found between TAS and phosphatemia in group 1 (p < 0.01) and between MDA and phosphatemia in group 2 (p < 0.01). A positive relationship between MDA and cholesterol levels was found in group 1 (p < 0.01). In conclusion, MDA values are increased and TAS values decreased in DKA and poorly controlled diabetes, and tend to correlate more with markers of diabetic imbalance than with markers of acute metabolic disturbances of DKA.     

Effect of aminoguanidine on lipid peroxidation in streptozotocin-induced diabetic rats.

Diabetes mellitus is postulated to be associated with increased lipid peroxidation, which may contribute to vascular complications. One potential mechanism of the increased lipid peroxidation in diabetes is lipid-linked advanced glycosylation and oxidation. Aminoguanidine (AMGN), the prototype inhibitor of advanced glycosylation end product (AGE) formation, has been recently shown to prevent oxidative modification of low-density lipoprotein (LDL) in vitro at a moderate concentration. It is unknown whether AMGN may act as an antioxidant against lipid peroxidation under hyperglycemia in vivo. To investigate the in vivo effect of AMGN on lipid peroxidation in diabetes, we administered AMGN (1 g/L in drinking water) or vitamin E (400 mg/d for 5 d/wk) to streptozotocin (STZ)-induced diabetic rats for 9 weeks and measured plasma lipid hydroperoxides by ferrous oxidation with xylenol orange II (FOX method) and red blood cell (RBC) membrane malondialdehyde (MDA) and related aldehydes as thiobarbituric acid-reactive substances (TBARS). Plasma lipid hydroperoxide was higher in STZ-induced diabetic rats versus control rats (mean +/- SD, 7.53 +/- 2.03 v 5.62 +/- 0.44 micromol/L, P < .05; n = 8 to 14). RBC membrane TBARS were also higher in STZ-induced diabetic rats than in control rats (2.67 +/- 0.46 v 1.81 +/- 0.19 nmol/mL, P < .05). Plasma lipid hydroperoxide was lower in AMGN-treated (6.23 +/- 0.59 micromol/L, P < .05) and vitamin E-treated (5.29 +/- 0.27 micromol/L, P < .05) diabetic rats than in untreated diabetic rats. RBC membrane TBARS were also lower in AMGN-treated (1.93 +/- 0.12 nmol/mL, P < .05) diabetic rats than in untreated diabetic rats. There was no significant difference in plasma glucose, cholesterol, and triglyceride levels among diabetic groups. Although the mechanism(s) of action of AMGN on lipid peroxidation in vivo should be studied further, these results suggest that AMGN may have an additional beneficial effect as an antioxidant against lipid peroxidation in a prevention trial for diabetic vascular complications.     

Antioxidant therapy potentiates antihypertensive action of insulin in diabetic rats

BACKGROUND: Poorly controlled longstanding diabetes frequently results in sustained hypertension (HTN) which plays a major role in the pathogenesis of diabetic nephropathy. In addition, hyperglycemia, per se, causes a reversible rise in blood pressure (BP) and increases production of reactive oxygen species (ROS). Increased ROS activity may raise BP by promoting inactivation of nitric oxide (NO) and/or nonenzymatic generation of vasoconstrictive prostaglandins from peroxidation of arachidonic acid. Therefore, we hypothesized that antioxidant therapy may enhance the BP-lowering effect of glycemia control with insulin replacement in diabetes. METHODS: Male Sprague-Dawley rats were rendered diabetic by streptozotocin administration and randomized to untreated, antioxidant-treated (vitamin E-fortified food, tocopherol 5000 U/kg chow and vitamin C-fortified H2O, 1000 mg/L), insulin-treated and insulin plus antioxidant-treated groups. Normal rats fed a regular diet or antioxidant-fortified diet served as controls and monitored for 4 weeks. RESULTS: The diabetic animals showed marked hyperglycemia, HTN, proteinuria, depressed tissue glutathione level and elevated plasma lipid peroxidation product, malondialdehyde (MDA) denoting increased ROS activity. Insulin therapy alone resulted in significant, but incomplete reduction in BP and plasma MDA but not proteinuria. Antioxidant therapy alone had no effect on the measured parameters in either the diabetic or control animals. However, combined insulin and antioxidant therapies normalized BP, plasma MDA and urinary protein in the diabetic animals. As expected, uncontrolled diabetes resulted in glomerular hyperfiltration which was partially reversed by insulin therapy, but was unaffected by antioxidant therapy. CONCLUSION: Uncontrolled hyperglycemia in the early phase of diabetes was associated with elevated plasma MDA, HTN and proteinuria. Insulin therapy alone resulted in significant but incomplete reduction of plasma MDA and BP. Antioxidant therapy which was ineffective when given alone, normalized plasma MDA, BP and reduced urinary protein excretion when combined with insulin treatment.     

Effect of estrogen on coronary vasoconstriction in patients undergoing coronary angioplasty

BACKGROUND: Estrogen has an antioxidant potential which may contribute to its cardioprotective effect. We sought to determine whether estrogen administration can affect coronary vasomotor tone in patients after angioplasty by reducing 8-iso-prostaglandin (PG) F(2alpha) concentrations, a bioactive product of lipid peroxidation. METHODS: The study was designed to prospectively investigate 30 consecutive patients scheduled for elective coronary angioplasty. Patients were randomized into two groups according to whether they did not (group 1, n = 15) or did have (group 2, n = 15) intracoronary (i.c.) treatment with estrogen prior to coronary angioplasty. RESULTS: There were no significant differences of collateral circulation assessed by intracoronary Doppler flow velocity during balloon inflations between the study groups. The diameters of the coronary artery at the dilated and distal segments were significantly reduced 15 min after dilation compared with those immediately after dilation in group 1 (both P < 0.0001). The vasoconstriction was significantly blunted in group 2. The 8-iso-PGF(2alpha) levels in plasma from the coronary sinus rose significantly from 194 +/- 45 to 390 +/- 97 pg/ml (P < 0.0001, 95% confidence intervals = 142-249 pg/ml) 15 min after angioplasty in group 1, which was attenuated after administering estrogen. Significant correlation was found between the changes of coronary vasomotion of the dilated segment and 8-iso-PGF(2alpha) levels in group 1 (r = 0.73, P = 0.002). CONCLUSIONS: 8-iso-PGF(2alpha) is released into the coronary circulation during angioplasty, and this vasoactive substance may contribute to the occurrence of vasoconstriction. Estrogen administration attenuated vasoconstriction by reducing the 8-iso-PGF(2alpha) levels. This finding may provide a new strategy to treat coronary vasoconstriction after angioplasty.