Murat Kaçmaz

Impaired antioxidant defense system in the kidney tissues from rabbits treated with cyclosporine. Protective effects of vitamins E and C.

Enzymatic antioxidant defense system and antioxidant defense potential (AOP) were studied in kidney tissue from rabbits treated with cyclosporine (CsA, 25 mg/kg/day), antioxidant vitamins (E, 100 mg/kg/day plus C, 200 mg/kg/day), and CsA plus antioxidant vitamins, and in kidney tissue from control animals. Although no change was observed in superoxide dismutase (SOD) activity, glutathione peroxidase (GSH-Px) and catalase (CAT) activities were found decreased in kidney tissue exposed to CsA for 10 days compared with control tissue. The level of thiobarbituric acid-reagent substances (TBARS) was higher and antioxidant defense potential (AOP) lower in the CsA-treated group compared with the other groups. Histopathological examination reveals important subcellular damage in the renal tissue from the animals treated with CsA. Antioxidant vitamin therapy caused full improvement in the enzyme activities, TBARS levels and AOP, but the subcellular damage was partly ameliorated in the CsA plus vitamin group. Results suggest that CsA impairs the antioxidant defense system and reduces the antioxidant defense potential in the renal tissue. Antioxidant vitamin treatment protects the tissue in part against toxic effects of the drug.

Oxidant/antioxidant status of plasma samples from patients with rheumatoid arthritis.

Abstract This study aims to elucidate plasma oxidant/antioxidant status in patients with rheumatoid arthritis (RA). Fasting blood samples were obtained from 24 patients with RA and 20 control subjects. Antioxidant potential (AOP) value, nonenzymatic superoxide radical scavenger activity (NSSA), and malondialdehyde (MDA) levels were measured to establish plasma oxidant/antioxidant status in the patient and control groups. Patients with RA had lower AOP and NSSA but higher MDA levels than those of the control subjects, which was an indication of reduced antioxidant capacity and oxidant stress in these patients. Results suggest that the antioxidant system is impaired and peroxidation reactions are accelerated in patients with RA. We suppose that therapeutic use of some antioxidants may be beneficial in this regard.

Oxidant/antioxidant status of the erythrocytes from patients with rheumatoid arthritis.

Abstract: It has been suggested that enzymatic and/or non-enzymatic antioxidant systems are impaired in rheumatoid arthritis (RA) and hence patients are exposed to oxidant stress. This study aimed to establish whether this is really the case. Fasting blood samples were obtained from 24 patients with rheumatoid arthritis and 20 controls. The activities of erythrocyte superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) and xanthine oxidase (XO) enzymes and malondialdehyde (MDA), oxidant resistant (OR) and non-enzymatic superoxide radical scavenger activity (NSSA) values were measured in both groups. Patients with RA had higher SOD and XO activities and MDA levels than did the controls. However, NSSA and OR levels were found to be decreased, and CAT and GSH-Px activities unchanged in the study group. Results suggest that excessive free radical production through the xanthine–xanthine oxidase system is the primary factor in rheumatoid arthritis, rather than an impaired antioxidant system. The therapeutic use of XO enzyme inhibitors and some antioxidants can be beneficial in this regard.

Antioxidant interferences in superoxide dismutase activity methods using superoxide radical as substrate.

Sir, In several methods for the measurement of the superoxide dismutase (SOD; E.C 1.15.1.1) activity, superoxide radical (O2• -) produced from various sources such as the xanthin/xanthine oxidase system, pyrogallol oxidation etc. has been used as the substrate (1–4). In general, SOD activity is measured on the basis of competition between O2• dismutation by this enzyme or by an oxidising substance such as nitroblue tetrazolium salt (NBT), nicotinamide adenine dinucleotide (NAD) etc. Accordingly, when SOD activity is high, reduction rate of the oxidising substance is low and vice versa. In these methods, there is however interference from non-enzymatic antioxidants, which mainly results from cellular components with antioxidant capacity. Some of these substances, such as hemoglobin, transferrin, albumin, ceruloplasmin and haptoglobin, exert their antioxidant activities by binding metal ions which play a part in free radical production. Others, such as uric acid and vitamins A, C and E, mainly act as chainbreaking antioxidants. Due to this fact, it is not possible to carry out a valid measurement of activity without removing these non-enzymatic antioxidant substances from the medium. Although some researchers use chloroform/ethanol extraction to eliminate these substances, this procedure cannot remove all of them; hydrophilic antioxidants remain in the alcohol/water phase. Therefore, in the present methods, total (enzymatic plus non-enzymatic) superoxide radical scavenger activity (TSSA) instead of SOD activity is measured. We have used human erythrocytes and, rabbit liver and lung to assess this interference. First, we measured SOD activites in erythrocyte hemolyzates and in lung and liver by using the method described previously (5, 6). Second, activity measurements were made in trichloroacetic acid (TCA)-treated fractions, which were prepared by treating part of the sample with 20 % (w/v) TCA solution and centrifuging at 5000 xg for 30 min. We observed that TCA-treatment causes no meaningful changes in the pH of the final assay mixture (pH = 10.5 in untreated assay and 10.2 in TCAtreated assay). Activity assays were performed in the supernatant fraction. One unit of SOD activity was defined as the amount of protein causing 50% inhibition in NBT reduction rate. Results are given in Table 1. As shown in the table, a significant amount of SOD activity still exists in the supernatant fluids after TCAtreatment, which have removed all enzyme. There must therefore be other, non-enzymatic, factors which remove O2• from the reaction medium. Therefore, activity values measured by the present methods should be regarded as TSSA rather than enzyme activity and SOD activity should be calculated from the equation below.

Effects of cigarette smoking with different tar content on erythrocyte oxidant/antioxidant status.

Abstract In this study, the effects of cigarettes with differing tar content on erythrocyte oxidant/antioxidant status was investigated. Malondialdehyde (MDA) as an indicator of oxidant status and superoxide radical scavenger activity (SSA) as an indicator of antioxidant status were measured in erythrocytes from 20 smokers and 10 non‐smoker controls. Ten of the 20 smoking subjects smoked five cigarettes with full flavour low tar (FFLT with 12 mg tar) and the others smoked five cigarettes with full flavour high tar (FF with 23 mg tar) over 1 hour. Initial blood samples from both groups at fasting, followed by further samples from smokers at 1.5 hours and 3 hours after smoking. Initial erythrocyte MDA level and SSA activity were found to be higher in the smoking groups compared to non‐smokers. Furthermore, both parameters were significantly higher at the 1.5‐hour and 3‐hour erythrocyte samples when compared to initial values in the FFLT group. However, there were no statistically significant differences between SSA values established at different times in FF group. Results suggest that smoking causes oxidant load in the erythrocytes. Although a compensatory mechanism (i.e. increased SSA activities) develops in the FFLT group after smoking, this cannot prevent peroxidation reactions (i.e. increased MDA levels) in the erythrocytes. As to the types of cigarettes, both seem to have oxidant potential, but oxidation degree in the FFLT group is higher than that of FF group. These results suggest that antioxidant supplementation to smokers might be beneficial to decrease cellular oxidation damages.

Halothane hepatotoxicity and hepatic free radical metabolism in guinea pigs; the effects of vitamin E

PurposeThe aim of this study was to investigate the relation between halothane hepatotoxicity and hepatic free radical metabolism and to establish a possible protective role of vitamin E against halothane hepatotoxicity.MethodsTwenty-eight guinea pigs were used in the experiments. Halothane (1.5% v/v) in oxygen (100%) was given to the animals for 90 min over three days. Livers from animals were then taken and prepared for the assays. In the enzymatic study, Superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT) activities were measured. As a peroxidation index, the malondialdehyde (MDA) concentration was determined. Also, electron spin resonance (ESR) analysis and electron microscopy (EM) were performed. Results: Superoxide dismutase (1168.3 ± 78.2 U · mg−1) and glutathione peroxidase (14.9 ± 6.2 mIU · mg−1) activities were decreased, but catalase activity (1260.0 ± 250.6 lU · mg−1) and malondialdehyde concentration (11.5 ± 1.8 ppb) were increased in liver tissues exposed to halothane compared with control values (1382.2 ± 91.8 U · mg−1 for SOD, 27.8 ± 5.2 mIU · mg−1 for GSH-Px, 840.2 ± 252.4 IU · mg−1 for CAT and 10.0 ± 1.0 ppb for MDA). Electron spin resonance analysis revealed a peak of CF3 CHCl radical in the exposed tissue. Electron microscopy indicated ultrastructural changes in the hepatic cells of both halothane groups with and without vitamin E treatment.ConclusionHalothane causes impairment in the hepatic antioxidant defense system and accelerates peroxidation reactions. As a result, some ultrastructural changes in hepatic tissues occur due to halothane treatment. Although vitamin E prevents peroxidative damage, it does not ameliorate ultrastructural changes caused by halothane treatment. This shows that halothane toxicity results not only from impaired hepatic antioxidant defense system but also from other, unknown causes.RésuméObjectifCette étude visait à examiner la relation possible entre l’hépatotoxicité à l’halothane et le métabolisme des radicaux libres et à vérifier si la vitamine E protège contre l’hépatotoxicité à, l’halothane.MéthodesVingt-huit cobayes ont été utilisés. De l’halothane (15% v/v) en oxygène (100%) a été administré aux animaux pendant 90 min sur une période de trois jours. Les foies ont alors été prélevés et préparés pour fin d’analyse. Pour l’étude enzymatique, l’activité de la superoxyde dismutase (SOD), de la glutathione peroxydase (GSH-Px) et de la catalase (CAT) a été mesurée. En tant qu ’indice de la peroxydation, la concentration de la malondialdéhyde (MDA) a été déterminée. En outre, on a procédé à des examens à la résonance paramagnétique électronique (Electronic spin resonance: ESR) et à la microscopie électronique (EM).RésultatsL’activité de la superoxyde dismutase (1168,3 ±78,2 U · mg−1) et de la glutathione peroxydase (14,9 ± 6,2 UI · mg−1) a diminué, mais celle de la catalase (1260,0 ± 250,6 Ul · mg−1) ainsi que la concentration de ta malondialdéhyde (11,5 ± 1,8 ppb) ont augmenté dans le tissus hépatique exposé à l’halothane comparativement aux valeurs de contrôle (1382,2 ± 91,8U · mg−1 pour SOD, 27,8 ± 5.2 mUI · mg−1 pour SGH-px, 840 ± 252,4 UI · mg−1 pour CAT et 10,0 ± 1,0 ppb pour MDA). La résonance paramagnétique a révélé un pic de radical CF3CHCl dans les tissus exposés. La microscopie électronique a montré des changements ultrastructuraux dans les cellules hépatiques chez les deux groupes halothane traités ou non à la vitamine E.ConclusionL’halothane provoque une altération du système de défense hépatique antioxydant et accélère les réactions de peroxydation. Il en résulte des changements ultrastructuraux des tissus hépatiques produits par l’exposition à l’halothane. Bien qu’elle prévienne le dommage peroxydatif, la vitamine E n’atténue pas les changements ultrastucturaux produits par l’exposition à l’halothane. Ceci montre que la toxicité à l’halothane résulte non seulement de l’altération du système de défense antioxydant mais aussi d’autres causes non déterminées.

Antioxidant Defense Potential of Rabbit Renal Tissues after ESWL: Protective Effects of Antioxidant Vitamins

Antioxidant defense potential, malondialdehyde (MDA) levels, and relative hydroxyl radical (OH·) concentrations were measured in order to establish the effects of extracorporeal shock wave lithotripsy (ESWL) on free radical production and antioxidant defense potential of the rabbit kidney tissues. Electron microscopic examination was also performed to observe ultrastructural changes. The antioxidant defense potential of the ESWL-treated tissues was found to be reduced, and the MDA levels increased as compared with controls. Vitamin (vitamin E plus C combination) pretreatment ameliorated antioxidant defense potential in part, prevented increases in MDA levels in the ESWL-treated tissues, and increased the antioxidant defense potential in the control kidney tissues. After ESWL, a significant amount of OH· radical was measured in the affected tissue. This revealed the source of oxidant stress and peroxidation reactions in the ESWL-treated kidney tissue. Vitamin pretreatment caused significant reduction in the OH· radical concentration. In the electron microscopic investigation, some significant subcellular changes, such as endothelial injury, loss of foot processes, damage of glomerular basal membrane, etc., were observed in the ESWL-treated renal tissue slices. Vitamin pretreatment to a great extent prevented formation of these subcellular changes. Our results suggest that the antioxidant capacity of the kidney tissue was reduced after ESWL treatment and that the tissue was exposed to oxidant stress. Vitamin pretreatment exerted significant protection against the radical damage.

Effects of isoflurane on nitric oxide metabolism and oxidant status of guinea pig myocardium

Background: Volatile anesthetics (VAs) have been shown to enhance myocardial recovery during reperfusion, the mechanism of which has not been clarified yet. It has been supposed that this effect of VAs may appear through antioxidative mechanisms.

Effects of smoking on plasma and erythrocyte antioxidant defense systems.

In this study, activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) enzymes were measured in the erythrocytes, and levels of thiobarbituric acid-reactive substances (TBARS) and antioxidant potential (AOP) values were measured in both erythrocyte and plasma samples from smokerS and nonsmokers. No significant differences were observed in erythrocyte parameters, serum triglycerides, and total cholesterol. AOP was significantly lower and TBARS level higher in the plasma samples from smokers compared with those of nonsmokers. Results suggest that smoking causes no impairment in the enzymatic antioxidant defense system and does not lead to oxidant stress in the erythrocytes, possibly because these cells have potent antioxidant defense capacity.

Comparison of Antioxidant Potentials of Red Wine, White Wine, Grape Juice and Alcohol

Antioxidant potential (AOP) and non-enzymatic superoxide radical scavenger activity (NSSA) values of red wine, white wine, grape juice and ethyl alcohol were assessed and values were compared. The effects of these beverages on serum AOP and NSSA values were also measured in vitro. Red wine, white wine and grape juice exert strong antioxidant activity in similar degrees and all produce significant effects on serum AOP and NSSA values. However, ethyl alcohol does not have either AOP or NSSA, nor does it have an effect on serum AOP or NSSA values. AOP values (nmol/ml h) of red wine, white wine and grape juice were 20.8 +/- 4.2, 23.2 +/- 4.0 and 24.6 +/- 4.8, respectively. NSSA values (U/ml) of red wine, white wine and grape juice were 30.4 +/- 6.8, 26.8 +/- 5.6 and 32.6 +/- 5.8, respectively. There were no statistically meaningful differences between AOP and NSSA values of the groups (p > 0.05 for all). Results suggest that red wine, white wine and grape juice all have high antioxidant potential to protect cellular structures against peroxidation reaction owing to their rich phenolic contents.