Ozcan Erel

A novel and automated assay for thiol/disulphide homeostasis

OBJECTIVES To develop a novel and automated assay determining plasma thiol/disulphide homeostasis, which consists of thiol-disulphide exchanges. DESIGN AND METHODS Native thiol and total thiol concentrations were synchronously measured as a paired test. In the first vessel, the amount of native thiol groups was measured by a modified Ellman reagent. At the parallel run, first, dynamic disulphide bonds were reduced to free thiol groups by NaBH(4). The unused reductant remnants were completely removed by formaldehyde. Thus, the total thiol amount could be accurately measured. Mercaptoethanol solutions were used as calibrators. The half value of the difference between total thiol and native thiol amounts gave the disulphide bond amount. RESULTS No separation step for the assay was needed. All processes were performed using an automated analyser within about 10 min. Plasma disulphide levels were 17.29±5.32 μmol/L, native thiol levels were 397±62 μmol/L and disulphide/native thiol per cent ratios were 4.32±1.49 in healthy subjects. Plasma disulphide levels were higher in patients with degenerative diseases and lower in patients with proliferative diseases. CONCLUSION An easy, inexpensive, practical, fully automated and also optionally manual spectrophotometric assay can be used to determine plasma dynamic thiol/disulphide homeostasis.

Increased oxidative stress associated with the severity of the liver disease in various forms of hepatitis B virus infection

BackgroundOxidative stress can be defined as an increase in oxidants and/or a decrease in antioxidant capacity. There is limited information about the oxidative status in subjects with hepatitis B virus infection. We aimed to evaluate the oxidative status in patients with various clinical forms of chronic hepatitis B infection.MethodsSeventy-six patients with hepatitis B virus infection, in whom 33 with chronic hepatitis, 31 inactive carriers and 12 with cirrhosis, and 16 healthy subjects were enrolled. Total antioxidant response and total peroxide level measurement, and calculation of oxidative stress index were performed in all participants.ResultsTotal antioxidant response was significantly lower in cirrhotics than inactive HbsAg carriers and controls (p = 0.008 and p = 0.008, respectively). Total peroxide level and oxidative stress index was significantly higher in cirrhotic (p < 0.001, both) and chronic hepatitis B subjects (p < 0.001, both) than inactive HbsAg carriers and controls. Total antioxidant response was comparable in chronic hepatitis B subjects, inactive HbsAg carriers and controls (both, p > 0.05/6). Total peroxide level and oxidative stress index were also comparable in inactive HBsAg carriers and controls (both, p > 0.05/6). Serum alanine amino transferase level was positively correlated with total peroxide level and oxidative stress index only in chronic hepatitis B subjects (p = 0.002, r = 0.519 and p = 0.008, r = 0.453, respectively).ConclusionOxidative stress occurs secondarily to increased total lipid peroxidation and inadequate total antioxidant response and is related to severity of the disease and replication status of virus in hepatitis B infection.

Effect of pistachio diet on lipid parameters, endothelial function, inflammation, and oxidative status: A prospective study

OBJECTIVE Recent studies have suggested that nuts have favorable effects beyond lipid lowering. We aimed to investigate effect of the Antep pistachio (Pistacia vera L.) on blood glucose, lipid parameters, endothelial function, inflammation, and oxidation in healthy young men living in a controlled environment. METHODS A Mediterranean diet was administered to normolipidemic 32 healthy young men (mean age 22 y, range 21-24) for 4 wk. After 4 wk, participants continued to receive the Mediterranean diet but pistachio was added for 4 wk by replacing the monounsaturated fat content constituting approximately 20% of daily caloric intake. Fasting blood samples and brachial endothelial function measurements were performed at baseline and after each diet. RESULTS Compared with the Mediterranean diet, the pistachio diet decreased glucose (P<0.001, -8.8+/-8.5%), low-density lipoprotein (P<0.001, -23.2+/-11.9%), total cholesterol (P<0.001, -21.2+/-9.9%), and triacylglycerol (P=0.008, -13.8+/-33.8%) significantly and high-density lipoprotein (P=0.069, -3.1+/-11.7%) non-significantly. Total cholesterol/high-density lipoprotein and low-density lipoprotein/high-density lipoprotein ratios decreased significantly (P<0.001 for both). The pistachio diet significantly improved endothelium-dependent vasodilation (P=0.002, 30% relative increase), decreased serum interleukin-6, total oxidant status, lipid hydroperoxide, and malondialdehyde and increased superoxide dismutase (P<0.001 for all), whereas there was no significant change in C-reactive protein and tumor necrosis factor-alpha levels. CONCLUSION In this trial, we demonstrated that a pistachio diet improved blood glucose level, endothelial function, and some indices of inflammation and oxidative status in healthy young men. These findings are in accordance with the idea that nuts, in particular pistachio nuts, have favorable effects beyond lipid lowering that deserve to be evaluated with prospective follow-up studies.

Decreased total antioxidant capacity and increased oxidative stress in passive smoker infants and their mothers

Abstract Background : Smoking has many adverse health effects in infants and adults. The purpose of the study was to study the effect of passive cigarette smoking on oxidative and antioxidative status of plasma in passive smoker infants and their mothers and to compare with those of non‐smokers.

EFFECTS OF TOBACCO SMOKING ON PLASMA SELENIUM, ZINC, COPPER AND IRON CONCENTRATIONS AND RELATED ANTIOXIDATIVE ENZYME ACTIVITIES

OBJECTIVES The aim of the study was to investigate whether alterations in antioxidative enzyme activities are dependent on their cofactor concentrations in tobacco smokers. DESIGN AND METHODS Plasma selenium, copper, zinc and iron concentrations, and the activities of related erythrocyte antioxidative enzymes copper-zinc superoxide dismutase (Cu-Zn SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) were measured in tobacco smokers and compared with those of nonsmokers. Plasma thiocyanate levels were measured as an index of smoking status. RESULTS While plasma copper concentration and erythrocyte Cu-Zn SOD activity were significantly higher, plasma selenium concentration and erythrocyte GSH-Px activities were significantly lower in tobacco smokers than in nonsmokers. There was no significant difference in plasma iron and zinc concentrations or erythrocyte CAT activity between the two groups. There were significant positive correlations between erythrocyte GSH-Px and plasma selenium levels, between Cu-Zn SOD and copper levels, and between CAT and iron levels, and a negative correlation between plasma thiocyanate and selenium content in tobacco smokers. CONCLUSIONS These findings suggest that antioxidative enzyme activities change depending on their cofactor concentrations in tobacco smokers.

The relationship between potency of oxidative stress and severity of depression

Background: Oxidative stress is one of the suggested mechanisms in major depression. Objective: To determine the oxidative and antioxidative status of plasma of patients with major depression and to investigate whether there is a relationship between the potency of oxidative stress and the severity of depression. Methods: To determine the antioxidative status of plasma, total and individual antioxidant levels which are total antioxidant potential (TAOP), total protein, albumin, uric acid, vitamin C and total bilirubin were measured. To determine the oxidative status, total peroxide level of plasma was measured in patients with drug-free depressive patients and compared with those of controls. Per cent ratio of total peroxide to TAOP was evaluated as oxidative stress index (OSI). Results: Plasma TAOP and individual antioxidant levels were found to be lower in patients with depression than those of controls. On the contrary, the patients had high total plasma peroxide levels. OSI values of the patients were significantly higher than those of controls (P = 0.002), and a significant positive correlation between Hamilton Depression Rating Scale (HDRS) and OSI values was found (r = 0.54, P = 0.01). Conclusions: The patients with major depression are exposed to oxidative stress, and OSI may be useful to reflect the severity of the disease.

Oxidative Stress and Antioxidative Status of Plasma and Erythrocytes in Patients with Vivax Malaria

OBJECTIVES To investigate the oxidative stress and antioxidative status of plasma and erythrocytes in patients with vivax malaria and healthy persons. DESIGN AND METHODS Activities of antioxidative enzymes, rates of pathways of hexose monophosphate shunt and purine salvage, levels of lipid peroxidation, reduced glutathione, methemoglobin and sulfhemoglobin of erythrocytes were determined. Lipid peroxidation and levels of antioxidant substances were measured. RESULTS Antioxidants levels and antioxidative enzymes activities were lower and lipid peroxidation, purine salvage rate were higher in patients group than controls. Erythrocyte glucose-6 phosphate dehydrogenase (G-6-PD) activity was not different from that of healthy subjects. CONCLUSIONS Oxidative mechanisms were observed to be dominant compared with antioxidative mechanisms in patients with vivax malaria. Therefore, oxidative stress may be produced and maintained by the host defense mechanisms against malarial infection.

Paraoxonase and arylesterase activities in coronary artery disease.

Background  Paraoxonase‐1 is an enzyme with three activities which are inversely related to cardiovascular diseases. Accordingly, the aim of the study was to investigate the paraoxonase, arylesterase activities and oxidative/anti‐oxidative status in coronary artery disease (CAD) and their correlation with the extent of CAD.

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.

Oxidative imbalance in obsessive compulsive disorder patients: A total evaluation of oxidant–antioxidant status

OBJECTIVES Various psychological, social, genetic, biochemical, factors are to be involved in the etiology of OCD. Some molecules of free radicals are also found to play role in OCD. To the best of our knowledge, there has been no study, regarding the role of free radicals in the pathogenesis of OCD, from a general antioxidant aspect of view. Therefore, in this present cross-sectional study, we aimed to assess whether antioxidant-oxidant status is associated with OCD and can be used or not as a biological marker regarding that disorder. METHODS 37 OCD patients diagnosed according to DSM-IV and as control group forty healthy subjects were included to the study. Venous blood samples were collected once. The total oxidant status, antioxidant status and oxidative stress index of the plasma were measured using a novel automated colorimetric measurement method. RESULTS There was not a significant difference between only OCD and all patients in all measures (TOS: Z = - 1.453, p = 0.521; TAS: Z = - 0.151, p = 0.880; OSI: Z = - 0.679 p = 0.497). TAS levels were both higher than controls in only OCD groups and all patients (Z = - 5.538, p < 0.001 and Z = - 6.394, p < 0.001 respectively). TOS and OSI of both patient groups were significantly lower than controls (TOS: Z = - 5.131, p < 0.001; OSI: Z = - 5.105, p < 0.001 and TOS: Z = - 5.979, p < 0.001; OSI: Z = - 5.862, p < 0.001). In only OCD group, illness duration was correlated with TOS and OSI (r(0) = 0.44, p = 0.023, n = 26 and r(0) = 0.44, p = 0.026, n = 26 respectively) but not with TAS. CONCLUSION Our study found an overall oxidative imbalance shifted towards antioxidant side in OCD which may be due to either a rebound phenomenon or chronicity of the condition.