A Yeşilkaya

Akdeniz University, Satalia, Antalya, Turkey

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Publications (10)8.12 Total impact

  • M U Senturk · U K Senturk · P Y Basak · O Kuru · A Yesilkaya ·

    Journal of the European Academy of Dermatology and Venereology 10/2003; 17(5):614-5. DOI:10.1046/j.1468-3083.2003.00770.x · 2.83 Impact Factor
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    ABSTRACT: Oxidant stress is one of the factors proposed to be responsible for damaged erythrocytes observed during and after exercise. The impact of exertional oxidant stress after acute exhaustive treadmill running on erythrocyte damage was investigated in sedentary (Sed) and exercise-trained (ET) rats treated with or without antioxidant vitamins C and E. Exhaustive exercise led to statistically significant increments in the levels of thiobarbituric acid-reactive substance (TBARS) and H2O2-induced TBARS in Sed rats and resulted in functional and structural alterations in erythrocytes (plasma hemoglobin concentrations, methemoglobin levels, and rise in osmotic fragility of erythrocytes with decrease in erythrocyte deformability). Administration of antioxidant vitamin for 1 mo before exhaustive exercises prevented lipid peroxidation (TBARS, H2O2-induced TBARS) in Sed rats without any functional or structural alterations in erythrocytes. Parameters indicating erythrocyte lipid peroxidation and deterioration after exhaustive exercise in rats trained regularly with treadmill running for 1 mo were not different from those in Sed controls. Erythrocyte lipid peroxidation (TBARS) increased in exhausted-ET rats compared with ET controls; however, the plasma hemoglobin, methemoglobin levels, and erythrocyte osmotic fragility and deformability did not differ. Exhaustive exercise-induced lipid peroxidation in ET rats on antioxidant vitamin treatment was prevented, whereas functional and structural parameters of erythrocytes were not different from those of the ET controls. We conclude that exertional oxidant stress contributed to erythrocyte deterioration due to exercise in Sed but not in ET rats.
    Journal of Applied Physiology 12/2001; 91(5):1999-2004. · 3.06 Impact Factor
  • D K Korgun · S Bilmen · A Yesilkaya ·
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    ABSTRACT: In the present study, we measured the concentrations of reduced glutathione (GSH) and malonyldialdehyde (MDA) and the activities of glutathione peroxidase (GSH-Px), glutathione S-transferase (GSH-S-T), superoxide dismutase (SOD), catalase (CAT) and glucose-6-phosphate dehydrogenase (G-6-PD) in erythrocytes obtained freshly from adult male donors which was preserved with CPDA-1 anticoagulant (citrate,phosphate, dextrose, adenine) on different days of storage. At the end of the study, storage-associated alterations in antioxidant activities were noted and discussed. GSH, GSH-Px, GSH-S-T, SOD, CAT and G-6-PD activities decreased, but erythrocyte MDA levels, as anindex of lipid peroxidation, increased during the storage period. According to our results, glutathione-dependent antioxidant systems in erythrocytes might be depleted during long storage in blood bags.
    Research communications in molecular pathology and pharmacology 02/2001; 109(5-6):357-63.
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    O Erdoğan · S Yildiz · A Başaran · A Demirbaş · A Yeşilkaya ·
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    ABSTRACT: Removal of free oxygen radicals, generated during reperfusion of an ischemic organ by scavengers protects the tissue from reperfusion injury. The calcium channel blocker verapamil is an effective cytoprotective agent, preventing against reperfusion injury. The effects of verapamil were investigated previously using hepatic, renal or cardiac ischemia-reperfusion injury models. We investigated the effects of intravenous and intraportal administration of verapamil in prevention from the injury caused by free oxygen radicals generated during hepatic ischemia-reperfusion in rats. Thirty six male Sprague-Dawley rats after laparotomy were subjected to hepatic ischemia for 30 and 45 min followed by 60 min of reperfusion. Two minutes before ischemia the rats were pretreated by intravenous or intraportal administration of verapamil. The levels of glutathione and thiobarbituric acid reacting substances (TBARs) referred to as malonyldialdehyde (MDA) and the serum levels of transaminases were measured in liver tissue 1 and 24 h after the onset of reperfusion. Statistical analysis of the data by Student's t-test showed statistically significant differences between the group pretreated intraportally with verapamil and the other groups. Verapamil given intraportally exerted more beneficial effect. Therefore, we conclude that intraportal verapamil administration reduces the ischemia-reperfusion injury caused by free oxygen radicals.
    Polish journal of pharmacology 01/2001; 53(2):137-41.
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    ABSTRACT: Nitric oxide (NO) plays a major role in vascular regulation. Modulation of NO synthesis is known to influence blood pressure. Inhibition of NO synthesis by NG-nitro-L-arginine methyl ester (L-NAME; 72 mg/kg/day, p.o., 21 days) resulted in 60% increase in blood pressure in rats. Red blood cell (RBC) transit time measured by the cell transit analyzer increased significantly in the L-NAME treated group, in comparison to normotensive rats. RBC aggregation measured in autologous plasma, by a photometric rheoscope also increased significantly in the hypertensive rats. RBC cytosolic free calcium concentration was also significantly higher in the hypertensive animals. Incubation of RBC from hypertensive and control animals with NO donor, sodium nitroprusside (SNP; 10-1000 microM) for 60 minutes resulted in a dose-dependent decrease in RBC aggregation, however aggregation index was significantly higher in hypertensive group at each SNP concentration. Incubation with SNP had no effect on RBC deformability in the control group, while a slight decrease in RBC transit time was observed only at 10 microM SNP in the hypertensive group. These results imply that NO may play a role in the regulation of rheological properties of RBC and the alterations in these properties may at least in part be involved in the development of L-NAME induced hypertension.
    Clinical hemorheology and microcirculation 02/2000; 22(4):267-75. · 2.24 Impact Factor
  • Akın Yeşilkaya · Ayşenur Yeğin ·
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    ABSTRACT: 1. The in vitro effects of cumene hydroperoxide and t-butyl hydroperoxide on intact human erythrocyte membrane (Na(+)-K+)ATPase activities have been studied. 2. (Na(+)-K+)ATPase activities on erythrocyte membranes decreased in agreement with the results of chemiluminescence experiments. 3. Our results demonstrated that the organic hydroperoxides inhibit the activity of (Na(+)-K+) ATPase enzyme and that the antioxidants used prevent this inhibition.
    General Pharmacology 04/1998; 30(4):495-8. DOI:10.1016/S0306-3623(97)00285-1
  • A Yeşilkaya · A Yeğin · S Ozdem · T A Aksu ·
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    ABSTRACT: Recently, it has been suggested that bilirubin may act as a potent biological chain-breaking antioxidant. To observe the effects of free bilirubin on antioxidant reactions in cumene hydroperoxide-treated erythrocytes (15 g hemoglobin/dl), we added bilirubin at four different concentrations (0.5, 1, 5, and 10 mg/dl). We measured the thiobarbituric acid-reactive substance and reduced glutathione levels, and some antioxidant enzyme activities, namely superoxide dismutase, catalase, and glucose-6-phosphate dehydrogenase. Thiobarbituric acid-reactive substance and chemiluminescent signals decreased during the incubation. Superoxide dismutase activities also decreased but not as much as in the control group. Glucose-6-phosphate dehydrogenase activities and reduced glutathione levels increased, but catalase activities remained the same as the control group. Our results suggest that bilirubin--in the concentrations we have used--partially prevented the oxidant effects of cumene hydroperoxide.
    International Journal of Clinical & Laboratory Research 02/1998; 28(4):230-4. DOI:10.1007/BF02874114
  • G Yücel · A Yeşilkaya · T A Aksu · A Yeğin · Y Alicigüzel ·
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    ABSTRACT: Erythrocytes and hemolysates from 10 normal and 10 glucose-6-phosphate dehydrogenase-deficient individuals were incubated with cumene hydroperoxide, and free radical-induced lipid peroxidation was monitored by chemiluminescence. Chemiluminescence intensities in erythrocytes of normal and deficient subjects were similar in the presence or absence of glucose-6-phosphate dehydrogenase substrates. Hemolysates of normal and deficient subjects also showed similar chemiluminescence in the absence of substrates. However, with the addition of substrates to the incubation medium, deficient hemolysates reached maximum chemiluminescence intensity within a shorter period, and maximum values were higher than in normal hemolysates. We believe this offers a new means of detection of glucose-6-phosphate dehydrogenase-deficient patients.
    International Journal of Clinical & Laboratory Research 02/1997; 27(1):55-9. DOI:10.1007/BF02827243
  • A Yeşilkaya · A Yeğin · G Yücel · Y Alicigüzel · T A Aksu ·
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    ABSTRACT: We studied the effect of cumene hydroperoxide, t-butyl hydroperoxide, and hydrogen peroxide on intact healthy human erythrocytes (15 g hemoglobin/dl) using chemiluminescence to monitor peroxidation. We measured the chemiluminescence spectrum, the process of hemolysis, the pH shift, and absorbance spectrum during the incubation with chemicals producing oxidative stress. Maximum chemiluminescence was reached with cumene hydroperoxide at about 50 min, but with t-butyl hydroperoxide at 100 min. The effect of organic hydroperoxide was concentration dependent, whereas the effect of hydrogen peroxide was independent of concentration. Peroxides induced hemolysis after 30 min. The pH shift to alkaline was observed in the first 20-min period. Incubation with organic hydroperoxides induced a decrease in absorption at 580, 545, and 345 nm. Hydrogen peroxide induced a decrease in the same period of time but this returned to the normal range by 120 min. There was no change in absorption at 420 nm with any of the peroxidative agents. Our results suggest that low-level chemiluminescence is a useful model for studying hydroperoxide-induced peroxidation in human erythrocytes.
    International Journal of Clinical & Laboratory Research 02/1996; 26(1):60-8. DOI:10.1007/BF02644778
  • S Gümüşlü · G Yücel · M Aydin · A Yeşilkaya · A Y Demir · T A Aksu ·
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    ABSTRACT: An experimental system which assesses the antioxidant potential of ascorbic acid, glutathione, uric acid, and taurine was developed. The system comprised hemoglobin, luminol, t-butyl hydroperoxide, and different concentrations of antioxidants in TRIS-HCl buffer (pH 7.4). Control assays were performed by excluding antioxidants. Chemiluminescence was detected using a liquid scintillation counter in single photon mode. All antioxidants, when applied in the appropriate concentrations, decreased the maximum chemiluminescence values. The minimum concentrations which decreased the chemiluminescence values were defined for each of the antioxidants.
    International Journal of Clinical & Laboratory Research 02/1996; 26(2):119-23. DOI:10.1007/BF02592354