Browsing by Author "Durak, I"

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Aspirin Enhances Myocardial Inducible Nitric Oxide Synthase Activity in Guinea Pigs
(Elsevier Science Bv, 1999) Durak, I; Karaayvaz, M; Öztürk, HS
Aspirin Impairs Antioxidant System and Causes Peroxidation in Human Erythrocytes and Guinea Pig Myocardial Tissue
(Sage Publications Ltd, 2001) Durak, I; Karaayvaz, M; Çimen, MYB; Avci, A; Çimen, ÖB; Buyukkoçak, S; Kaçmaz, M
This study aims to investigate possible effects of aspirin treatment on cellular oxidant/antioxidant system. In the first part of the study, 15 guinea pigs were given aspirin at three different doses (2200, 440 and 10 mg/kg/day) for 30 days and five were fed on the same diet without aspirin. After a month, animals were killed and their hearts were removed for use in analyses. In the other part, after fasting blood samples were obtained from 11 volunteer subjects, they were given aspirin (approximately 10 mg/kg/day) for 30 days and second blood samples were obtained after 1 month. Five volunteer subjects also participated as placebo control. Oxidant/antioxidant parameters, namely superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase (CAT), malondialdehyde (MDA), nonenzymatic superoxide scavenger activity (NSSA), susceptibility to oxidation (SO) and antioxidant potential (AOP) values, were assayed in the samples. Antioxidant system was found to be impaired in the heart tissue from guinea pigs and in the erythrocytes from volunteer subjects. AOP and NSSA values were lower and MDA higher after aspirin treatment in both heart tissues and erythrocytes. In guinea pig heart tissue, SO was lower, but GSH-Px and CAT were unchanged after aspirin treatment. In human erythrocytes, SO was unchanged, but GSH-Px and CAT activities were increased after aspirin treatment. Changes in guinea pig heart tissues from animals treated with higher aspirin doses were more drastic relative to those of human erythrocytes, but no meaningful differences were observed between analysis parameters of control and lower-dose (10 mg/kg/day) aspirin-treated animals. Our results suggest that high-dose aspirin exerts significant toxicity to guinea pig myocardium and normal dose aspirin may cause peroxidation in the human erythrocytes due to its oxidant potential. We suppose that antioxidant supplementation may be beneficial for the people using aspirin for longer periods in order to prevent peroxidation damages.
Cisplatin Induces Acute Renal Failure by Impairing Antioxidant System in Guinea Pigs
(Taylor & Francis Ltd, 2002) Durak, I; Özbek, H; Karaayvaz, M; Öztürk, HS
This study aims to investigate the role of oxidants in cisplatin-induced nephrotoxicity. Cisplatin was administered intraperitoneally (i.p.) in a single dose (5mg/kg) and guinea pigs were killed either after 24h or 7 days. The same experiment was performed using animals treated with vitamins C and E combination and a natural antioxidant extract (SARMEX((R))). The kidneys were then removed to be used in the analyses. Blood samples were also obtained from the animals to be used in routine biochemical assays. Twenty-four hours after treatment there was a significant decrease in the renal activities of total superoxide scavenger activity (TSSA), superoxide dismutase (SOD) and catalase (CAT) accompanied by a rise in malondialdehyde (MDA) levels. After 7 days, the fall in kidney enzymatic activities was far greater, while the increase in blood urea (BUN) and creatinine (CRE) was marked. Treatment with antioxidants causes significant increases in renal TSSA (7 day), non-enzymatic superoxide scavenger activity (NSSA) (24h and 7 day) and SOD (7 day) activities, does not change glutathione peroxidase (GSH-Px) activity and decreases renal MDA (24h and 7 day), blood BUN (7 day) and CRE (7 day) levels. Our results suggest that cisplatin treatment impairs both enzymatic and non-enzymatic antioxidant systems and causes peroxidation in the renal tissue, which leads to kidney failure. Antioxidant supplementation strengthens the renal antioxidant system, eliminates oxidation reactions, and prevents cisplatin-induced kidney failure.
Cyclosporine Reduces Hepatic Antioxidant Capacity
(Elsevier Science Bv, 2004) Durak, I; Özbek, H; Elgün, S
The immunosuppressive agent cyclosporine A (CsA) has been reported to exert measurable hepatotoxic effects. One of the causes leading to hepatotoxicity is thought to be reactive oxygen radical formation. Therefore, this study was designed to elucidate possible relation between cyclosporine A treatment and antioxidant capacity (AOC) of hepatic tissue and, to determine if antioxidant supplementation is beneficial. Cyclosporine A was given to 20 rabbits orally for 10 days. Vitamins E and C combination were given intramuscularly. Vitamin therapy was started 3 days before cyclosporine A treatment and continued for 10 days. In each group (control, cyclosporine A, cyclosporine A+ vitamin, and vitamin only) there were five animals. After the animals were sacrificed, their livers were removed to be used in the AOC measurement. AOC was found to be lower in cyclosporine A group compared to control and vitamin groups. Results suggest that reduced antioxidant capacity may play part in the cyclosporine A-induced hepatotoxicity and use of some antioxidants may give beneficial results. (C) 2004 Published by Elsevier B.V.
Effects of Cholesterol Supplementation on Antioxidant Enzyme Activities in Rat Hepatic Tissues
(Elsevier Sci Ltd, 2004) Durak, I; Özbek, H; Devrim, E; Karagenç, N; Ergüder, IB
Background and Aim: The effects of cholesterol supplementation on antioxidant enzyme activities were investigated in hepatic tissue taken from Sprague Dawley rats. Methods and Reults: The study involved 14 male Sprague Dawley rats: seven fed a normal laboratory diet and seven a normal diet plus cholesterol (3.6 g/kg/day) for three months, during which blood samples were obtained to measure serum cholesterol levels. At the end of the 3-month period, the livers were surgically removed in order to measure antioxidant enzyme activities (superoxide dismutase, catalase, glutathione peroxidase and paraoxonase-1). At the end of the study period, serum total cholesterol and HDL-cholesterol levels were significantly higher in the cholesterol-fed group than the control group. There were no significant between-group differences in hepatic superoxide dismutase, catalase and glutathione peroxidase activities, but there was a significant decrease in hepatic paraoxonase-1 activity in the cholesterol-fed group. Conclusions: Cholesterol supplementation significantly decreases paraoxonase-1 activity in rat liver tissue without changing the activities of other antioxidant enzymes. These results suggest that cholesterol significantly suppresses hepatic paraoxonase-1 synthesis. It seems that the decreased paraoxonase-1 activity in the plasma HDL-fraction of atherosclerotic patients is associated with suppressed liver synthesis. A reduction in paraoxonase-1 activity may therefore lead to the more intensive exposure of LDL to oxidant attacks. Nutr Metab Cardiovasc Dis ((C)) 2004, Medikal.
Effects of Garlic Extract Consumption on Blood Lipid and Oxidant/Antioxidant Parameters in Humans With High Blood Cholesterol
(Elsevier Science inc, 2004) Durak, I; Kavutcu, M; Aytaç, B; Avci, A; Devrim, E; Özbek, H; Öztürk, HS
Effects of garlic extract supplementation on blood lipid profile and oxidant/antioxidant status were investigated in volunteer subjects with high blood cholesterol. A total of 23 volunteer subjects with high blood cholesterol (>5.98 mmol/L) participated in the study. Of them, 13 patients were evaluated as a hypertensive group and the others a normotensive group. Before (first sample) and after (second sample) garlic extract consumption for 4 months, routine blood analyses including lipid parameters and liver and kidney function tests were performed. Additionally, blood oxidant (malondialdehyde [MDA], oxidation resistance [OR]), and antioxidant (antioxidant potential [AOP], nonenzymatic superoxide radical scavenger activity [NSSA]) parameters were measured. Serum total cholesterol, low-density lipoprotein (LDL) and very-low-density lipoprotein (VLDL) cholesterols, and triglyceride levels were found to be significantly lowered, but HDL high-density lipoprotein cholesterol level increased after the extract use. The total:HDL cholesterol ratio was also found to be significantly decreased after the extract use. There were no meaningful differences with regard to other routine biochemical parameters. Additionally, blood AOP, OR, and NSSA values were found increased and MDA level decreased in the second samples relative to the first ones. Systolic and diastolic blood pressure values were also found to be significantly lowered after extract supplementation in the hypertensive group, but no similar changes were observed in the normotensive group. We conclude that garlic extract supplementation improves blood lipid profile, strengthens blood antioxidant potential, and causes significant reductions in systolic and diastolic blood pressures. It also leads to a decrease in the level of oxidation product (MDA) in the blood samples, which demonstrates reduced oxidation reactions in the body. (C) 2004 Elsevier Inc. All rights reserved.