Erythrocyte Malondialdehyde Research Articles

Ovariectomy exacerbates oxidative stress and cardiopathyinduced by adriamycin

Ovarian hormone depletion in ovariectomized experimental animals is a useful model with which to study the physiopathological consequences of menopause in women. It has been suggested that menopause is a risk factor for the induction of several cardiovascular disorders. In the present study we analyzed the effects of ovarian hormone depletion by ovariectomy (OVX) in a model of oxidative stress and cardiopathy induced by adriamycin (AD). To evaluate these effects, we measured parameters related to cardiac damage (creatinine kinase, lactate dehydrogenase, aspartate aminotransferase and alanine aminotransferase) and oxidative stress (malondialdehyde, catalase, superoxide dismutase, glutathione peroxidase, reduced glutathione, nitric oxide and carbonyl proteins) in cardiac tissue and erythrocytes. OVX was found to alter all markers of oxidative stress and cell damage in cardiac tissue. Similarly, the OVX-derived loss of ovarian hormones enhanced cardiac damage and oxidative stress induced by AD. Our results suggest that antioxidant status in cardiac tissue and erythrocytes is seriously compromised by OVX during the cardiomyopathy induced by AD in experimental animals. In conclusion, the absence of hormones caused by OVX or menopause may induce or accelerate pre-existing cardiovascular dysfunctions.

The Effect of Resveratrol in Experimental Cataract Model Formed by Sodium Selenite

Purpose: To investigate if resveratrol can prevent sodium selenite-induced experimental cataract model in rats. Methods: Forty-eight Spraque-Dawley rat pups were divided into 3 treatment groups: (1) normal saline–% 5 ethanol injected i.p. on postpatum day 10; (2) Na selenite (30 nmol/g body wt) injected s.c on day 10; (3) Na selenite s.c on day 10 + resveratrol (40 mg/kg) i.p on days 10–13. On day 21, cataract development was graded by slit-lamp examination and photography. Encapsulated lenses and erythrocytes were analyzed for reduced glutathione (GSH) and malondialdehyde (MDA), a marker of lipid peroxidation. Lenses were also analyzed for total nitrite (TN). Results: All control lenses in group 1 were clear. In group 2, all rats developed cataracts (grade 3–grade 6), whereas in group 3, only 9 of 16 rats developed cataracts (grade 2–grade 3). The difference of cataract frequency between groups 2 and 3 was statistically significant (p < 0.05). Group 3 lenses and erythrocytes had higher mean GSH and lower mean MDA levels than those in group 2 (p < 0.05). TN was highest in group 3 and lowest in group 1 (p < 0.05). Conclusions: Resveratrol suppressed selenite-induced oxidative stress and cataract formation in rats. This protective effect was supported by higher GSH and lower MDA in lens and erythrocytes. The presence of oxidative stress in selenite cataract development and its prevention by resveratrol support the possibility that high natural consumption of resveratrol in food can help prevent human senile cataract.

Evidence for systemic oxidative stress in tobacco chewers

Objective. To evaluate erythrocyte malondialdehyde (MDA) levels and activities of superoxide dismutase (SOD) and glutathione reductase (GR) in tobacco chewers, in view of possible oxidative stress in oral smokeless tobacco. Material and methods. Sixty healthy male tobacco chewers, aged 30.6±4.7 years with a 3 to 10‐year (7.37±2.1) history of tobacco chewing, were included in the study. Thirty‐two healthy male volunteers, aged 26.5±4.8 years, served as controls. All the participants were from the same community and of similar dietary habits. Results. The erythrocyte MDA level and activities of erythrocyte SOD and GR were estimated. There was a significant duration‐ (tobacco chewing) dependent increase in erythrocyte MDA levels along with a significant duration‐ (tobacco chewing) dependent decrease in erythrocyte SOD and GR activity. Conclusion. Oral smokeless tobacco causes a duration‐dependent increase in oxidative stress.

Effect of dantrolene on lipid peroxidation, glutathione and glutathione-dependent enzyme activities in experimental otitis media with effusion in guinea pigs

The aims of our study were to assess whether the increased oxidative stress in experimental otitis media with effusion (OME) induced by histamine was reflected erythrocytes and middle ear effusion fluid by lipid peroxidation; to survey the alterations in antioxidant enzyme activities in experimental OME; and to determine the effect of dantrolene on this oxidative stress. Erythrocyte and middle ear effusion malondialdehyde (MDA) level, erythrocyte glutathione (GSH) and glutathione peroxidase (GSH-Px), glutathione reductase (GRD) and glutathione-S-transferase (GST) activities were measured in three groups of seven guinea pigs, 3 hours after injection of 0.1 mL of histamine (or saline) into the middle ear in guinea pigs with OME (experimental group), in a dantrolene sodium group and in a control group. Erythrocyte and effusion MDA levels in the dantrolene group were significantly lower than those of the experimental group. Erythrocyte GSH-Px, GST, GRD activities, and GSH levels were significantly higher in the dantrolene group than in the experimental group. Dantrolene sodium decreased the erythrocyte and effusion MDA levels, on the other hand, it increased the GSH and GSH-dependent enzymes. These findings suggest that reactive oxygen species (ROS) play a role in histamine-induced OME. Pre-treatment with dantrolene sodium increases antioxidant enzymes activities and decreases formation of MDA, the indicator of lipid peroxidation, in histamine-induced OME.

Effects of Trimetazidine on Lipid Peroxidation, Antioxidant Enzyme Activities and Plasma Brain Natriuretic Peptide Levels in Patients with Chronic Cor Pulmonale

An oxidant/antioxidant imbalance in favour of oxidants appears to occur in chronic cor pulmonale (CCP). Oxidative stress could also be a critical event in the pathogenesis of this condition. Trimetazidine (TMZ) has antioxidant properties and may affect the utilization of oxygen radicals. We investigated the effect of TMZ (20 mg three times daily, orally) on activities of erythrocyte malondialdehyde (MDA) and catalase (eCAT), erythrocyte and plasma glutathione peroxidase (GSH-Px) and plasma superoxide dismutase (pSOD) in CCP patients. We also assessed changes in plasma levels of brain natriuretic peptide (BNP) with TMZ therapy. Sixty CCP patients with significantly higher MDA and markedly lower pSOD, eCAT and GSH-Px (erythrocyte) activities than 24 healthy controls were randomly allocated to receive routine treatment or routine treatment plus TMZ. After 3 months' therapy, greater pSOD, eCAT and GSH-Px (erythrocyte and plasma) activities and lower MDA activity were found with TMZ treatment compared with routine treatment. Plasma BNP levels were significantly lower in TMZ-treated patients and higher in the routine treatment group than in the control group. TMZ improved antioxidant levels, decreased oxidative stress and decreased plasma BNP levels in CCP patients.

Hypoglycemic and antioxidant effect of oleuropein in alloxan-diabetic rabbits

Patients with diabetes mellitus are likely to develop certain complication such as retinopathy, nephropathy and neuropathy as a result of oxidative stress and overwhelming free radicals. Treatment of diabetic patients with antioxidant may be of advantage in attenuating these complications. Oleuropein, the active constituent of olive leaf ( Olea europaea), has been endowed with many beneficial and health promoting properties mostly linked to its antioxidant activity. This study aimed to evaluate the significance of supplementation of oleuropein in reducing oxidative stress and hyperglycemia in alloxan-induced diabetic rabbits. After induction of diabetes, a significant rise in plasma and erythrocyte malondialdehyde (MDA) and blood glucose as well as alteration in enzymatic and non-enzymatic antioxidants was observed in all diabetic animals. During 16 weeks of treatment of diabetic rabbits with 20 mg/kg body weight of oleuropein the levels of MDA along with blood glucose and most of the enzymatic and non-enzymatic antioxidants were significantly restored to establish values that were not different from normal control rabbits. Untreated diabetic rabbits on the other hand demonstrated persistent alterations in the oxidative stress marker MDA, blood glucose and the antioxidant parameters. These results demonstrate that oleuropein may be of advantage in inhibiting hyperglycemia and oxidative stress induced by diabetes and suggest that administration of oleuropein may be helpful in the prevention of diabetic complications associated with oxidative stress.

Effect of α-tocopherol on the metabolic control and oxidative stress in female type 2 diabetics

In this study we evaluate the effects of α-tocopherol on the metabolic control and oxidative stress in female patients with type 2 diabetes mellitus. Thirty-four female type 2 diabetics 40–70 years old up to 14 years with diabetes, under medical treatment, were randomly divided in two groups. One group received placebo (Control group, n = 21) and the other received α-tocopherol (800 IU/day, n = 13) during 6 weeks. Blood samples were collected at the beginning and at the end of the study to measure malondialdehyde production, glycated hemoglobin, selenium dependent-glutathione peroxidase, Cu,Zn-superoxide dismutase in erythrocytes and total antioxidant status, glucose, lipid and lipoproteins in serum. Erythrocyte malondialdehyde decreased and serum-total antioxidant status increased after α-tocopherol treatment ( P < 0.0001). However, an unexpected increase on cholesterol levels and a reduced erythrocyte-Cu,Zn-superoxide dismutase activity was observed after α-tocopherol treatment. α-Tocopherol administration did not affect glucose, glycated hemoglobin, triacylglycerides, lipoprotein levels and serum malondialdehyde. A minor oxidative stress was observed in female type 2 diabetic patients after α-tocopherol treatment inferred from the reduced levels of erythrocyte malondialdehyde and the increased values of total antioxidant status. On the other hand, no beneficial changes were observed on glycemic control or lipid metabolism.

Effects of Simvastatin on Oxidative Stress in Streptozotocin-Induced Diabetic Rats: A Role for Glomeruli Protection

Aims: To study the effects of simvastatin on oxidative stress in rats with early stage diabetic nephropathy. Methods: 60 male Sprague-Dawley rats were divided into three groups: control group (CN), streptozotocin (STZ)-induced diabetic rats group (DM) and STZ-induced diabetic rats group treated with simvastatin (DM+S). The following parameters were measured at weeks 6 and 12 in similar rats chosen randomly from each group: body and kidney weight, 24-hour urinary albumin excretion (UAE), biochemical indexes including blood glucose (GLU), low-density lipoprotein (LDL), high-density lipoprotein (HDL), triglycerides (TG), serum creatinine (SCr), antioxidant enzymes including superoxide dismutase (SOD), glutathione S-transferase (GST), catalase (CAT) in plasma, lipid peroxidation production as malondialdehyde in plasma (MDAp) and erythrocytes (MDAe), morphology parameters such as glomerular volume (GV) and mesangial area/total glomerular area (M/T). Results: At weeks 6 and 12, GLU and kidney weight to body weight ratio were notably increased in both of the diabetic groups compared with those in the CN group without significant differences between the two diabetic groups. There were no significant differences of SCr, LDL, HDL and TG among all groups within all the experimental time. MDAp and MDAe were significantly increased in both of the diabetic groups, especially at week 12, while SOD, GST and CAT were significantly decreased compared with those in the CN group. At week 12, GV, M/T and UAE were also increased in the two diabetic groups. However, in the DM+S group, changes of lipid peroxidation production, antioxidant enzymes, UAE and GV were less pronounced than those in the DM group. Pearson’s correlation analysis and regression analysis shown that MDAp was increased while SOD, GST and CAT in plasma were decreased with elevation of UAE, GV and M/T. Conclusion: Increased lipid peroxidation and decreased antioxidant enzymes in plasma may play a role in the progression of diabetic nephropathy. Simvastatin may ameliorate these changes to protect kidney from oxidative lesion in diabetes even in the absence of lipid abnormalities.

Roles of Free Radicals, Nitric Oxide, and Scavenging Enzymes in Nasal Polyp Development

The aim of this study was to investigate the role of nitric oxide (NO), free oxygen radicals, and scavenging enzymes in the development of nasal polyp (NP) disease. This study included 41 patients who underwent endoscopic surgery because of NPs. Control specimens were taken from the inferior turbinate of 32 patients who underwent septoplasty. The levels of malondialdehyde (MDA), NO, and superoxide dismutase (SOD) were measured in intraoperative specimens of polyp tissue and turbinate mucosa. The levels of tissue NO were 191.06 +/- 26.62 micromol/mg of protein in patients with NPs and 145.30 +/- 19.19 micromol/mg of protein (p < .001) in the control group. The levels of MDA in the study and control groups were 12.47 +/- 2.12 nmol/mg and 8.83 +/- 1.08 nmol/mg (p < .01), respectively. The levels of SOD in the study and control groups were 50.77 +/- 14.74 U/mg and 77.93 +/- 15.31 U/mg (p < .001), respectively. It was determined that the levels of MDA in plasma and erythrocytes were higher in the patients with NPs than in the control group (p < .05). The levels of NO in plasma and erythrocytes in both groups were similar. The levels of SOD in plasma and erythrocytes were lower in patients with NPs than in the control group (p > .05). Increases in the levels of tissue MDA and NO and decreases in scavenging enzymes in patients with NPs as compared to control groups may indicate the presence of free radical damage in patients with nasal NPs. New studies are needed to clarify the efficacy of using antioxidants in the treatment of NPs.

Cyclosporine A induced changes to plasma and erythrocyte antioxidant defences

Organ transplant recipients develop pronounced cardiovascular disease, and decreased antioxidant capacity in plasma and erythrocytes is associated with the pathogenesis of this disease. These experiments tested the hypothesis that the immunosuppressant cyclosporine A (CsA) alters erythrocyte redox balance and reduces plasma antioxidant capacity. Female Sprague-Dawley rats were randomly assigned to a control or CsA treated group. Treatment animals received 25 mg/kg/day of CsA via intraperitoneal injection for 18 days. Control rats were injected with the same volume of the vehicle. Three hours after the final CsA injection, rats were exsanguinated and plasma analysed for total antioxidant status (TAS), α-tocopherol, malondialdehyde (MDA), and creatinine. Erythrocytes were analysed for superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX) and glucose-6-phosphate dehydrogenase (G6PD) activities, α-tocopherol, and MDA. CsA administration resulted in a significant (P < 0.05) decrease in plasma TAS and significant increases (P < 0.05) in plasma creatinine and MDA. Erythrocyte CAT was significantly (P < 0.05) increased in CsA treated rats compared to controls. There were no significant differences (P > 0.05) in erythrocyte SOD, GPX, G6PD, α-tocopherol or MDA between groups. In summary, CsA alters erythrocyte antioxidant defence and decreases plasma total antioxidant capacity.

Evaluation of oxidative–antioxidative status and the l-arginine–nitric oxide pathway in asthmatic patients

Reactive nitrogen, oxygen species and oxidative stress are related to many pulmonary diseases. Nitric oxide (NO) may be involved in either the protection against or the induction of oxidative stress within various tissues. It is derived from the amino acid L-arginine by the action of NO synthase (NOS). L-arginine can also be metabolized by arginase with the production of ornithine and urea. Because of the competition between NOS and arginase for the same substrate, their activities are regulated reciprocally. Therefore, the rate of NO generation associated with oxidative stress is dependent on the relative activities of both NOS and arginase. The objective of this study is to investigate the L-arginine-NO pathway, evaluate oxidative-antioxidative status in the patients with asthma and demonstrate their reciprocal regulation. 30 voluntary asthmatic patients and 30 healthy control subjects with similar age range and sex were included in the study. A total of 10 ml venous blood was drawn, plasma and packed erythrocytes were prepared for the biochemical analyses. Plasma arginase activities and NO levels, and erythrocyte malondialdehyde and reduced glutathione levels were detected. Plasma malondialdehyde levels were significantly higher and glutathione levels were lower in patients with asthma than those of the control subjects (P < 0.001 and P < 0.01, respectively). Arginase activities were significantly lower and NO levels were higher in the patients than those of the controls (P < 0.001 for both). The negative correlation between arginase and NO levels in the patients was significant (r = -0.47; P < 0.01). There was also a positive correlation between malondialdehyde and NO levels in the patients (r = 0.51; P < 0.01). The results suggest that the L-arginine-NO pathway is involved in the pathophysiology of asthma; the arginase activities decrease which causes an increase in the L-arginine levels thereby up-regulation of NO production may contribute to the increase of oxidative stress in asthma.

Investigation of oxidative stress during fracture healing in the rats

One of the most damaging effects of reactive oxygen species (ROS) is lipid peroxidation, the end-product of which is malondialdehyde (MDA). This study was aimed to evaluate erythrocyte MDA levels during fracture healing in rats. Thirty male rats were used and the rats were divided into two groups to serve as controls and tests. Six rats were used as a control group that was not subject to fracture. The remaining 24 rats were divided into four groups and erythrocyte MDA levels were examined on days 5, 10, 20 and 30 post fracture. The right fibulas of rats were broken by manual angulation in the experimental group. The erythrocyte malondialdehyde level was measured in the experimental and control groups. The difference between malondialdehyde levels of control and experimental groups was statistically significant (p<0.05). Oxidative stress clearly increases during fracture healing in rats.

Glutathione peroxidase, glutathione-S-transferase, catalase, xanthine oxidase, Cu–Zn superoxide dismutase activities, total glutathione, nitric oxide, and malondialdehyde levels in erythrocytes of patients with small cell and non-small cell lung cancer

Lung cancer is a common pathology with high mortality due to late diagnosis. Glutathione peroxidase (GSH-Px), glutathione-S-transferase (GST), catalase (CAT), xanthine oxidase (XO), Cu–Zn superoxide dismutase (Cu–Zn SOD) activities, total glutathione (TGSH), nitric oxide (NO ), and malondialdehyde (MDA) levels were investigated in erythrocytes of patients with non-small-cell lung cancer (NSCLC) and small-cell lung cancer (SCLC), and healthy control group. We aimed to investigate serum GSH, GSH-dependent enzymes activities (GSH-Px and GST), XO, CAT, Cu–Zn SOD activity, and NO , and MDA levels in patients with NSCLC and with SCLC and correlate with the cancer stage. Erythrocyte MDA, NO , TGSH levels and erythrocyte SOD, CAT and XO activities were significantly higher in patients with NSCLC and SCLC than in controls. Slightly increased erythrocyte GSH-Px and GST activities were not significantly different from the controls. Erythrocyte MDA level positively correlated with erythrocyte NO levels in patients with early stage (I+II) in NSCLC groups. Erythrocyte MDA level positively correlated with erythrocyte XO activity in patients with advanced stage (III+IV) in NSCLC groups. However, no other correlation could be found among the parameters in healthy controls and patients with NSCLC and with SCLC. Results obtained in this study indicate significant changes in antioxidant defence system in NSCLC and SCLC patients, which may lead to enhanced action of oxygen radical, resulting in lipid peroxidation.

Blood micronutrient, oxidative stress, and viral load in patients with chronic hepatitis C

To assess the extent of micronutrient and oxidative stress in blood and to examine their linkages with viral loads in chronic hepatitis C patients. Hepatitis C virus (HCV)-RNA levels were quantified in the serum from 37 previously untreated patients with chronic hepatitis C. The plasma and erythrocyte micronutrients (zinc, selenium, copper, and iron) were estimated, and malondialdehyde (MDA) contents were determined as a marker to detect oxidative stress. Antioxidant enzymes, superoxide dismutase (SOD), glutathione peroxidase (GPX) and glutathione reductase (GR) activities in blood were also measured. The control group contained 31 healthy volunteers. The contents of zinc (Zn), and selenium (Se) in plasma and erythrocytes were significantly lower in hepatitis C patients than in the controls. On the contrary, copper (Cu) levels were significantly higher. Furthermore, plasma and erythrocyte MDA levels, and the SOD and GR activities in erythrocytes significantly increased in hepatitis C patients compared to the controls. However, the plasma GPX activity in patients was markedly lower. Plasma Se (r = -0.730, P<0.05), Cu (r = 0.635), and GPX (r = -0.675) demonstrated correlations with HCV-RNA loads. Significant correlation coefficients were also observed between HCV-RNA levels and erythrocyte Zn (r = -0.403), Se (r = -0.544), Cu (r = 0.701) and MDA (r = 0.629) and GR (r = 0.441). The levels of Zn, Se, Cu, and oxidative stress (MDA), as well as related anti-oxidative enzymes (GR and GPX) in blood have important impact on the viral factors in chronic hepatitis C. The distribution of these parameters might be significant biomarkers for HCV.

Relation between oxidative stress markers and antioxidant endogenous defences during exhaustive exercise

Hydrogen peroxide (H2O2) could induce oxidative damage at long distance from its generation site and it is also an important signalling molecule that induces some genes related to oxidative stress. Our objective was to study the plasma and blood cells capability to detoxify H2O2 after intense exercise and its correlation with oxidative damage. Blood samples were taken from nine professional cycling, participating in a mountain stage, under basal conditions and 3 h after the competition. Catalase and glutathione peroxidase activities decreased (40 and 50% respectively) in neutrophils after the cycling stage, while glutathione peroxidase increased (87%) in lymphocytes. Catalase protein levels and catalase specific activity maintained basal values after the stage in plasma. Catalase protein levels decreased (48%) in neutrophils and its specific activity increased up to plasma values after exercise. Myeloperoxidase (MPO) increased (39%) in neutrophils after the cycling stage. Exercise-induced hemolysis and lymphopenia inversely correlated with cellular markers of oxidative stress. Plasma malondialdehyde (MDA) directly correlated with neutrophil MPO activity and erythrocytes MDA. Intense exercise induces oxidative damage in blood cells as erythrocytes and lymphocytes, but not in neutrophils.

Short-term very low calory diet reduces oxidative stress in obese type 2 diabetic patients

Oxidative stress is higher in obese diabetic than in non-diabetic subjects. This pilot study evaluates oxidative stress during short-term administration of a very low calorie diet in obese persons. Nine obese Type 2 diabetic patients (age 55+/-5 years, BMI 35.9+/-1.9 kg/m2) and nine obese non-diabetic control subjects (age 52+/-6 years, BMI 37.3+/-2.1 kg/m2) were treated by a very low calorie diet (600 kcal daily) during 8 days stay in the hospital. Serum cholesterol, triglycerides, non-esterified fatty acids (NEFA), beta-hydroxybutyrate (B-HB), ascorbic acid (AA), alpha-tocopherol (AT), plasma malondialdehyde (MDA) and superoxide dismutase (SOD) activity in erythrocytes were measured before and on day 3 and 8 of very low calorie diet administration. A decrease of serum cholesterol and triglyceride concentrations on day 8 was associated with a significant increase of NEFA (0.30+/-0.13 vs. 0.47+/-0.11 micromol/l, p<0.001) and B-HB (0.36+/-.13 vs. 2.23+/-1.00 mmol/l, p<0.001) in controls but only of B-HB (1.11+/-0.72 vs. 3.02+/-1.95 mmol/l, p<0.001) in diabetic patients. A significant decrease of plasma MDA and serum AT together with an increase of SOD activity and AA concentration (p<0.01) was observed in control persons, whereas an increase of SOD activity (p<0.01) was only found in diabetic patients after one week of the very low calorie diet. There was a significant correlation between NEFA or B-HB and SOD activity (p<0.01). We conclude that one week of a very low calorie diet administration decreases oxidative stress in obese non-diabetic but only partly in diabetic persons. Diabetes mellitus causes a greater resistance to the effects of a low calorie diet on oxidative stress.

Malondialdehyde and carbonyl contents in the erythrocytes of streptozotocin-induced diabetic rats

Oxidative stress is involved in degenerative disease, including atherosclerosis and diabetes mellitus. Impaired antioxidantdefense mechanism may be an important factor in the pathogenesis of diabetes. Oxidative stress can be measured bymonitoring the changes in blood malondialdehyde and carbonyl content. Determination of carbonyl level is used as anindex of the extent of the oxidative damage of protein. Moreover, malondialdehyde level is a marker of lipid oxidation. Weinvestigated the status of lipid peroxidation and protein oxidative damage in erythrocytes of streptozotocin (STZ) induceddiabetic rats by measuring erythrocyte malondialdehyde and carbonyl levels using a spectrophotometer. We found thatcarbonyl and malondialdehyde levels were significantly increased in the erythrocytes of STZ-induced diabetic rats. Thisobservation indirectly suggests an increase in free radical-mediated damage of the cell membrane.

Changes of Oxidative Stress Parameters in Diabetic Pregnancy

The molecular aetiology of disturbed embryogenesis and other unfavourable outcomes in offspring of diabetic mothers is not fully understood. Experimental studies have suggested an involvement of radical oxygen species (ROS) in the teratological process. To investigate if maternal diabetes in humans is capable of inducing alterations in vascular oxidative stress parameters and whether such changes are associated with disturbances in foetal development. Seventy patients with pre-gestational diabetes (PGDM) were chosen for the study: 29 (41.4%) belonged to class B according to White, 15 (21.4%) to class C, 8 (11.4%) to class D, 3 (4.3%) to class F, 3 to class R and 12 (17.1%) to class F/R. In 20 (28.6%) patients from this group an unfavourable outcome was noted. All patients were subjected to intensive insulin therapy. Glycaemia was estimated by daily self-monitoring, and diurnal glucose profiles and glycated haemoglobin (HbA1c) concentrations were measured monthly. Oxidative stress was evaluated as changed superoxide dismutase, catalase and glutathione peroxidase activities as well as of malondialdehyde (MDA) and peroxides concentrations in maternal erythrocytes and blood serum. Prior to conception, the mean glycaemia in the group that had a planned pregnancy was 6.6mmol/l and HBA1c was 9.35%. Throughout the course of pregnancy, these parameters were maintained at a level of 6.7 mmol/l and 7.85%, respectively. The activity of all antioxidative enzymes was lower before than during pregnancy, and so was the concentration of MDA. The MDA concentrations were higher in patients with elevated glycaemia and with an unfavourable outcome. The investigated ROS, the glycaemia level, as well as the concentration of HBA1c did not show any significant differences between pregnancies with and without vascular complications. Patients with a favourable perinatal outcome presented a higher activity of antioxidant enzymes, than those with unfavourable outcome, throughout the whole course of pregnancy. The appearance of unfavourable perinatal outcomes in relation to parameters of oxidative stress was assessed by logistic regression. Both SOD and GPX activities, as well as peroxides' concentration, showed significant correlations (p < 0.005) with foetal complications. However, after mean glucose levels in the studied group were included into these analyses, this relationship was only evident with SOD and GPX activity (p < 0.0016). Oxidative stress is one of several important factors contributing to unfavourable outcome of human diabetic pregnancy.

Quercetin, a flavonoid antioxidant, prevents and protects streptozotocin-induced oxidative stress and β-cell damage in rat pancreas

The aim of the present study was the evaluation of possible protective effects of quercetin (QE) against β-cell damage in experimental streptozotocin (STZ)-induced diabetes in rats. STZ was injected intraperitoneally at a single dose of 50 mg kg −1 for diabetes induction. QE (15 mg kg −1 day, intraperitoneal (i.p.) injection) was injected for 3 days prior to STZ administration; these injections were continued to the end of the study (for 4 weeks). It has been believed that oxidative stress plays a role in the pathogenesis of diabetes mellitus (DM). In order to determine the changes of cellular antioxidant defense system, antioxidant enzymes such as glutathione peroxidase (GSHPx), superoxide dismutase (SOD) and catalase (CAT) activities were measured in pancreatic homogenates. Moreover we also measured serum nitric oxide (NO) and erythrocyte and pancreatic tissue malondialdehyde (MDA) levels, a marker of lipid peroxidation, if there is an imbalance between oxidant and antioxidant status. Pancreatic β-cells were examined by immunohistochemical methods. STZ induced a significant increase lipid peroxidation, serum NO concentrations and decreased the antioxidant enzyme activity. Erythrocyte MDA, serum NO and pancreatic tissue MDA significantly increased ( P < 0.05) and also the antioxidant levels significantly decreased ( P < 0.05) in diabetic group. QE treatment significantly decreased the elevated MDA and NO ( P < 0.05), and also increased the antioxidant enzyme activities ( P < 0.05). QE treatment has shown protective effect possibly through decreasing lipid peroxidation, NO production and increasing antioxidant enzyme activity. Islet cells degeneration and weak insulin immunohistochemical staining was observed in STZ induced diabetic rats. Increased staining of insulin and preservation of islet cells were apparent in the QE-treated diabetic rats. These findings suggest that QE treatment has protective effect in diabetes by decreasing oxidative stress and preservation of pancreatic β-cell integrity.

Oxidative stress and antioxidant status in elderly diabetes mellitus and glucose intolerance patients

Increased oxidative stress and impaired anti-oxidant defense have been suggested as contributory factors for initiation and progression of complications in diabetes mellitus. Aging itself has been shown to be along with increased oxidative stress and lower anti-oxidant defense. We aimed at investigating oxidative stress and anti-oxidant enzymes in 61 elderly subjects. Fifteen healthy individuals (group 1, mean age 72.2 ± 5.13), 13 glucose intolerant patients (group 2, mean age 71.7 ± 4.9), 19 patients with type 2 diabetes mellitus (T2DM) without any complication (group 3, mean age 70.0 ± 6.0), and 14 patients with T2DM with at least one complication (group 4, mean age 69.8 ± 4.7) were included in the study. Whilst plasma levels for malondialdehyde (MDAP) and erythrocyte malondialdehyde (MDAE) were measured as markers of oxidative stress, activity of erythrocyte superoxide dismutase (SOD), glutathion peroxidase (GSH-Px), and catalase (CAT) were taken as markers of oxidative defense system. MDAP level was significantly elevated in group 4 ( P = 0.001). MDAE was elevated in patients with T2DM, particularly in group 4, however, the difference between the groups was of borderline significance ( P = 0.07). Whilst CAT was elevated in groups 3 and 4 compared to control subjects ( P = 0.025 and 0.002, respectively), no difference was found for SOD between the groups. GSH-Px activity was found to be increased in groups 2, 3 and 4, it did not reach statistical significance ( P = 0.106). There were significant correlations between CAT and MDAE ( P < 0.0001, r = 0.056) and MDAP ( P = 0.016, r = 0.306). These results suggest that there was an increased oxidative stress in elderly diabetics, however, this is not due to reduced erythrocyte antioxidant defense potential but, rather, increased free radical production possibly due to hyperglycemia.