Nurten Aksoy

Melatonin inhibits lipid peroxidation and stimulates the antioxidant status of diabetic rats

Although melatonin has been established as a free radical scavenger and antioxidant, its effects in diabetes have not been thoroughly investigated. The purpose of this study, therefore, was to investigate the effects of melatonin administration on lipid peroxidation and antioxidant status in streptozotocin (STZ)‐induced diabetes in rats. Concentrations of malondialdehyde (MDA) and reduced glutathione (GSH) in erythrocytes and activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH‐Px) were compared in 3 groups of 10 rats each [control non‐diabetic rats (group I), untreated diabetic rats (group II) and diabetic rats treated with melatonin (group III)]. In the study groups, diabetes developed 3 days after intraperitoneal (i.p.) administration of a single 60‐mg/kg dose of STZ. Thereafter, while the rats in group II received no treatment, the rats in group III began to receive a 10‐mg/kg i.p. dose of melatonin per day. After 6 wk, the rats in groups II and III had significantly lower body weights and significantly higher blood glucose levels than the rats of group I (P<0.001 and P<0.001, respectively). There were no significant differences in body weight or blood glucose levels between groups II and III. MDA levels in untreated diabetic rats were higher than those in control group rats and in diabetic rats treated with melatonin (P<0.01 and P<0.05, respectively). However, MDA levels in diabetic rats treated with melatonin were not different from those of the control group. The GSH, GSH‐Px and SOD levels of untreated diabetic rats were significantly lower than those of the control group (P<0.02, P<0.002 and P<0.05, respectively). In group III, however, melatonin prevented decreases in the thiol antioxidant and the associated enzymes, and so these levels were not significantly different from those in the control group. These results confirm the presence of oxidative stress in STZ‐induced experimental diabetes and indicate the beneficial free radical‐scavenging and antioxidant properties of melatonin.

The role of oxidative stress in diabetic retinopathy

Purpose To investigate the role of oxidative stress in the development of diabetic retinopathy.Methods This study included 25 patients with diabetic retinopathy (group 1), 34 patients with non-insulin-dependent diabetes mellitus without any angiopathy complications (group II) and 26 healthy subjects (group III). The serum malondialdehyde (MDA)-like metabolite levels as an index of lipid peroxidation, the erythrocyte glutathione peroxidase (GSH-Px), superoxide dismutase (SOD) and serum vitamin C levels of the patients and healthy subjects were measured.Results The mean serum concentration of MDA-like metabolites of patients in group I was 4.38 ± 1.31 nmol/ml, in group II was 3.38 ± 0.95 nmol/ml and in group III was 2.61 ± 0.85 nmol/ml. There were significant differences between the groups (p = 0.001 for group I compared with group II, p = 0.0001 for group I compared with group III and p = 0.002 for group II compared with group III). There was a significant correlation between the serum lipid peroxidation concentrations and duration of the disease (r = 0.36, p = 0.047). The mean erythrocyte GSH-Px and SOD levels of group I were respectively 68.97 ± 18.04 and 1597.78 ± 296.46 U/g Hb, of group II were 64.30 ±19.26 and 1581.33 ± 278.08 U/g Hb, and of group III were 65.52 ± 17.58 and 1587.44 ± 281.17 U/g Hb. There were no significant differences among the antioxidant enzyme levels in the three groups (p > 0.05). The mean serum vitamin C level in group I was 42.72 ± 8.90 μmol/l, in group II was 49.26 ± 11.52 μmol/l and in group III was 58.57 ± 9.75 μmol/l. There were significant differences among the mean serum vitamin C levels of the three groups (p = 0.02 for group I versus group II p = 0.001 for group I versus group III and p = 0.002 for group II versus group III).Conclusions Free radicals forming in diabetes mellitus and increasing over time may play a role in the development of diabetic retinopathy, which is an important complication of the disease.

Oxidative stress of platelets and thrombocytopenia in patients with vivax malaria

Oxidative stress and antioxidative capacity of platelets and the relationship with thrombocytopenia were determined in patients with vivax malaria and compared with those of healthy subjects. Whole blood thrombocyte count, platelet superoxide dismutase and glutathione peroxidase activities of patients with vivax malaria were lower and platelet lipid peroxidation levels were higher in patients than those of healthy subjects. There was an important negative correlation between whole blood thrombocyte count and platelet lipid peroxidation level. The antioxidative mechanisms of thrombocytes were insufficient in malaria patients and caused oxidative stress. The oxidative damage of thrombocytes might be important in the ethiopathogenesis of thrombocytopenia occurring in malaria.

The association of serum prolidase activity with the presence and severity of coronary artery disease.

ObjectivesProlidase is a cytosolic exopeptidase that cleaves iminodipeptides with carboxy-terminal proline or hydroxyproline and plays major role in collagen turnover. Collagen is the essential content in atherosclerotic plaque playing a key role in the stability/instability of and progression of coronary artery disease (CAD). Consequently, in this study we sought to determine serum prolidase activity and markers of oxidative stress such as lipid hydroperoxide and total free sulfhydryl in CAD. Design and methodsWe have evaluated 199 patients with CAD and 122 control cases with clinical, electrocardiographic, and laboratory investigation. We have measured serum prolidase activity and serum total free sulfhydryl levels spectrophotometrically. Serum lipid hydroperoxide levels were determined with ferrous ion oxidation-xylenol orange method. We assessed the association of serum prolidase activity with the presence and severity of CAD and clinical characteristics, and laboratory parameters. ResultsSerum prolidase activity (52.5±5.6 vs. 46.7±5.1 U/l, respectively, P<0.001) and serum lipid hydroperoxide levels were significantly increased in patients with CAD compared with control cases whereas, serum total free sulfhydryl levels were significantly decreased in patients with CAD compared with control cases. Serum prolidase activity and total free sulfhydryl levels were independent predictors of the presence of CAD [(χ2=75.532, ß=0.212, P=0.003) and (χ2=25.969, ß=−30.486, P=0.019), respectively] and Gensini score [(&bgr;=0.276, P<0.001) and (&bgr;=−0.274, P<0.001), respectively]. Independent predictors of serum prolidase activity were serum high-density lipoprotein cholesterol (&bgr;=−0.138, P=0.023) and urea levels (&bgr;=0.146, P=0.036), and Gensini score (&bgr;=0.317, P<0.001). ConclusionFindings of this study have shown that serum prolidase activity is significantly associated with the presence and severity of CAD, and elevated serum prolidase activity might be an independent predictor of coronary atherosclerosis.

Non-diabetic metabolic syndrome and obesity do not affect serum paraoxonase and arylesterase activities but do affect oxidative stress and inflammation

OBJECTIVE Paraoxonase-1 (PON-1), which has PON and arylesterase activities, is a high-density lipoprotein (HDL)-bound antioxidant enzyme that inhibits atherosclerosis. Diabetes has been shown to have an impact on oxidative stress. The effect of metabolic syndrome (MetS) on oxidative stress and PON-1 has been shown before, and PON-1 has been found to be related with accelerated atherogenesis. This study aimed to determine the oxidative state and PON and arylesterase activities in non-diabetic MetS and non-MetS obese patients. DESIGN Thirty obese patients (3 M and 27 F) without MetS, 40 non-diabetic obese patients (3 M and 37 F) with MetS, and 30 controls (2 M and 28 F) were enrolled. METHODS A 75 g glucose tolerance test was performed. PON-1, PON, arylesterase, total antioxidant status (TAS), high-sensitive C-reactive protein (hsCRP), and metabolic parameters were analyzed. RESULTS PON and arylesterase activities were similar between the groups, while TAS was low in both MetS and obese groups compared to controls (P<0.01 and P<0.05 respectively). CRP was higher in the MetS group compared with the obese and control groups (P<0.01 and P<0.001 respectively). In both the obese and MetS groups, CRP showed a positive correlation with body mass index (BMI). TAS was negatively correlated with BMI, waist circumference, triglyceride levels, and systolic and diastolic blood pressures (P<0.001). CONCLUSIONS Oxidative stress is altered in non-diabetic MetS and non-MetS obese patients, but PON and arylesterase activities seem not to be affected. This result may be due to the absence of diabetes, the most severe form of altered carbohydrate metabolism.

Melatonin protects from ischemia/reperfusion‐induced renal injury in rats: this effect is not mediated by proinflammatory cytokines

Abstract:  The pathophysiologic mechanisms leading to acute ischemic renal failure are not completely understood. Melatonin, a compound with well‐known antioxidant properties, reduces IR‐induced renal injury. The purpose of the present study was to investigate the changes in levels of tumor necrosis factor (TNF)‐α, IL‐β, and IL‐6 in postischemic reperfused renal tissue, and to determine whether the protective effect of melatonin is related the modulation of the production of these inflammatory molecules. Male Wistar albino rats were unilaterally nephrectomized and subjected to 1 hr of renal pedicle occlusion followed by 2 hr or 24 hr of reperfusion. Melatonin (10 mg/kg, i.p.) or vehicle was administrated at 10 min prior to ischemia. After 24 hr of the reperfusion, following decapitation, kidney samples were taken both for histologic examination and for the determination of malondialdehyde (MDA), myeloperoxidase (MPO) activity, total antioxidant capacity (TAC), total oxidative stress (TOS), creatinine, and blood urea nitrogen (BUN). These were measured in serum samples. TNF‐α, IL‐β, and IL‐6 were measured in kidney samples after 2 hr of reperfusion. IR caused a significant increase in renal MDA, MPO, TOS, creatinine, and BUN while decrease TAC without any change in TNF‐α, IL‐β, and IL‐6 levels. Melatonin treatment reduced the biochemical indices without any change in the cytokine levels and ameliorated histopathologic alterations induced by IR. The protective effect of melatonin on IR‐induced renal injury is related to its antioxidant properties but not to proinflammatory cytokines.

Protective Effects of Nigella sativa against Ischemia-Reperfusion Injury of Kidneys

Background. Ischemia-reperfusion, commonly seen in the fields of trauma surgery and renal transplantation, is a major cause of acute kidney injury and is associated with significant morbidity and mortality. The protective effects of Nigella sativa against ischemia-perfusion damage to various organs have been previously documented. However, its protective effects on kidney tissue against ischemia-reperfusion injury are unclear. In this study, we aimed to examine the effect of Nigella sativa in modulating inflammation and apoptosis after renal I/R injury. Materials and methods. Thirty male Wistar-albino rats were divided into three groups: sham-operated, ischemia-reperfusion, and ischemia-reperfusion + Nigella sativa. Rats in the third group were given Nigella sativa 6 h prior to ischemia-reperfusion and at the beginning of reperfusion. All rats except those in the sham-operated group underwent 45 min of bilateral renal ischemia followed by 45 min of reperfusion. Blood samples and liver tissues were harvested from the rats, and then rats were sacrificed. Serum urea and creatinine levels were determined. Total antioxidant capacity (TAC), catalase (CAT), total oxidant status (TOS), oxidative stress index (OSI), and myeloperoxidase (MPO) in kidney tissue and blood were measured. Kidney tissue histopathology was also evaluated. Results. Nigella sativa was effective in reducing serum urea and creatinine levels as well as decreasing the tubular necrosis score. Nigella sativa treatment significantly reduced OSI and TOS levels and increased TAC levels in both kidney tissue and blood. Conclusion. The observed differences seem to demonstrate the protective effect of Nigella sativa against renal I/R injury in rat kidneys.

Helicobacter pylori seroprevalence in patients with chronic obstructive pulmonary disease and its relation to pulmonary function tests.

Background: Chronic obstructive pulmonary disease (COPD) is a slowly progressive condition characterized by poorly reversible airflow limitation that is associated with an abnormal inflammatory response of the lung. It has been shown that there is a seroepidemiological association of Helicobacter pylori (Hp) infection with many inflammatory conditions. Objective: In this study, we aimed to investigate seroprevalence in Hp patients with COPD and to determine whether there is an association between Hp infection and COPD. Methods: Forty-nine voluntary patients with COPD and 50 healthy control subjects of similar age and sex were included in the study. Hp-specific IgG was measured with a commercially available kit from venous blood samples. Results: Serum levels of Hp-specific IgG and Hp IgG seropositivity were significantly higher in the patients with COPD than in the control subjects (p < 0.001 and p = 0.006, respectively). In addition, when the patients with COPD were grouped according to Hp IgG seropositivity, forced expiratory volume in 1 s (FEV1) values were lower in the seropositive patients compared to seronegative patients, and Hp serum IgG levels were correlated with FEV1 values, which indicate the severity of COPD, in the COPD group (r = –0.306, p = 0.032). Conclusion: The results suggest that there is an association between Hp infection and COPD, and Hp IgG levels are correlated with the severity of COPD.

Increased prolidase activity and oxidative stress in PCOS.

Matrix metalloproteinases (MMPs) have been considered to have a role in various pathological processes, including inflammatory response, cardiovascular disease and recently also in ovarian dysfunction. Since prolidase could be accepted as a matrix metalloproteinase, on the biochemical level, we aimed to evaluate serum prolidase activity and oxidative–antioxidative status in patients with polycystic ovary syndrome (PCOS) and healthy individuals.

Serum prolidase activity and oxidative stress markers in pregnancies with intrauterine growth restricted infants

Aim:  To compare the levels of serum prolidase activity and oxidative stress markers, including total oxidative status (TOS), total antioxidant capacity (TAC), oxidative stress index (OSI), and total free sulfhydryl (–SH) in healthy pregnant women and pregnant women with intrauterine growth restricted infants.