Person: YALÇIN, AHMET SUHA
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YALÇIN
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AHMET SUHA
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Publication Metadata only The functional assessment of autotransplanted splenic tissue by its capacity to remove oxidatively modified erythrocytes(1997) YALÇIN, AHMET SUHA; Haklar, G.; Demirel, M.; Peker, O.; Eskitürk, A.; Işgör, A.; Söyletir, G.; Yalçin, A. S.Free radicals and reactive oxygen species have been implicated in the pathogenesis of a variety of hematologic diseases and erythrocyte aging. Aged erythrocytes are removed from the circulation primarily by the spleen. In this study, we aimed to determine the functional effectiveness of autotransplanted splenic tissue by its capacity to remove oxidatively modified erythrocytes from the circulation. Our experimental model in rats includes splenectomy with autotransplantation of 80% of the excised splenic tissue into the omental pouch. In this model, free radical damage was estimated by different parameters of lipid peroxidation such as carbonyl content and thiobarbituric acid reactive substances (TBARS), together with Heinz body formation. Our results have shown that splenic autotransplantation was effective in removing oxidatively modified, aged erythrocytes from the circulation.Publication Metadata only Oxygen radicals and nitric oxide in rat mesenteric ischaemia-reperfusion: Modulation by L-arginine and N-G-nitro-L-arginine methyl ester(WILEY, 1998) YALÇIN, AHMET SUHA; Haklar, G; Ulukaya-Durakbasa, C; Yuksel, M; Dagli, T; Yalcin, AS1. The aims of the present study were to detect changes in superoxide anion (O-2(.-)), nitric oxide (NO) and other reactive oxygen species (ROS) directly by measurement of chemiluminescence (CL) and to investigate the role of L-arginine, a nitric oxide synthase (NOS) substrate, and N-G-nitro-L-arginine methyl ester (L-NAME), a NOS inhibitor, together with their molecular enantiomers D-arginine and D-NAME, in a rat mesenteric ischaemia-reperfusion (I/R) model. 2, Seventy-nine female Wistar albino rats were divided into eight groups, The first three groups underwent sham operation; group 1 was the control group, group 2 received L-arginine and group 3 received L-NAME. Ischaemia was produced in the remaining five groups by ligation of the superior mesenteric artery for 30 min followed by 60 min reperfusion, Group 4 rats were control I/R rats and groups 5-8 received either L-arginine, L-NAME, D-arginine or D-NAME, respectively. 3, Both luminol and lucigenin CL was significantly increased in I/R groups compared with sham-operated groups. L-Arginine significantly reduced CL measurements. D-Arginine was also protective, but not as much as L-arginine. Both L- and D-arginine had in vitro O-2(.-)-scavenging potential, as tested by the xanthine-xanthine oxidase system. N-G-Nitro-L-arginine methyl ester decreased lipid peroxidation values in addition to reducing CL measurements. Nitric oxide concentrations were significantly increased in VR groups in comparison with sham-operated groups. Peroxynitrite formation was increased by I/R. Treatment with L-NAME was beneficial by reducing NO concentrations in the reperfused ileum, 4, In our I/R model, O-2(.-), NO and other ROS were increased. Although NOS inhibitors were effective in reducing oxidative damage, increasing NO concentrations with L-arginine was also beneficial, presumably due to the ability of L-arginine to inhibit phagocyte adherence and its radical scavenging potential. In fact, NO may have different effects in terms of tissue injury or protection depending on the concentration of oxygen and the haemodynamic state of the tissue.Publication Metadata only Effect of cold-restraint stress on glutathione and lipid peroxide levels in the liver and glandular stomach of rats(1990) YALÇIN, AHMET SUHA; Yeğen, B.; Dedeoğlu, A.; Aykaç, I.; Oktay, S.; Yalçin, A. S.The effect of starvation and cold-restraint stress on glutathione and lipid peroxide levels in the liver, stomach and plasma of rats was investigated. Hepatic and gastric glutathione levels were significantly decreased in starvation and cold-restraint groups when compared with values obtained from the control group. In both tissues, lipid peroxide levels were significantly decreased after starvation but were not significantly different from control values after cold-restraint treatment. However, when compared with the values obtained from the starvation group there was a significant increase in both hepatic and gastric lipid peroxide levels after cold-restraint. Plasma lipid peroxide levels were slightly decreased in the starvation group and significantly increased in the cold-restraint group. Our results suggest that pathological consequences of stress on different tissues could be due to stimulation of lipid peroxidation.Publication Metadata only PROTECTIVE EFFECTS OF CILAZAPRIL AGAINST FREE-RADICAL INJURY IN MYOCARDIAL ISCHEMIA-REPERFUSION(ACADEMIC PRESS (LONDON) LTD, 1995) YALÇIN, AHMET SUHA; HAKLAR, G; ERSAHIN, C; MOINI, H; SUNGUN, M; DOGAN, N; BILSEL, S; EMERK, K; YALCIN, ASCilazapril is a prodrug which is rapidly hydrolysed to the pharmacologically active cilazaprilat following absorption to the bloodstream. In clinical pharmacological studies, administration of cilazapril resulted in potent, reversible, selective and competitive angiotensin converting enzyme inhibition. In this study, we have examined the protective effect of cilazapril on a myocardial ischaemia-reperfusion model by using different parameters of lipid peroxidation and protein oxidation. We have observed increased levels of diene conjugates, carbonyls and malondialdehyde as well as protein carbonyls after ischaemia-reperfusion, whereas protein sulphydryl groups were decreased. Our results clearly demonstrate that cilazapril, a non-sulphydryl, long-acting angiotensin converting enzyme inhibitor, has free-radical-scavenging potential in a model comparable to the clinical situation observed in humans.Publication Metadata only EFFECT OF CHRONIC HALOTHANE EXPOSURE ON LIPID-PEROXIDATION, OSMOTIC FRAGILITY AND MORPHOLOGY OF RAT ERYTHROCYTES(JOHN WILEY & SONS LTD, 1990) YALÇIN, AHMET SUHA; TOKER, K; OZER, NK; YALCIN, AS; TUZUNER, S; GOGUS, FY; EMERK, KPublication Metadata only Interaction of 3H-defibrotide with cultured human umbilical vein endothelial cells(1990) YALÇIN, AHMET SUHA; Bilsel, S.; Yalçin, A. S.; Taga, Y.; Emerk, K.Defibrotide is a profibrinolytic and antithrombotic drug which seems to modulate endothelial cell function. In this study, a method for radioactive labeling of the drug and its interaction with cultured endothelial cells is proposed. 3H-Acetic anhydride was used to label defibrotide. Endothelial cells obtained by collagenase treatment of human umbilical cord veins were cultured in 24-welled plastic culture dishes. Binding experiments were carried out by incubating cell cultures with media containing various concentrations of labeled defibrotide. Our results showed that labeled defibrotide has a KL value of 4.2 micrograms/ml for endothelial cells. Although the presence of a specific transporter is possible, the high molecular weight of the fraction used suggests that the interaction is binding to a specific receptor.Publication Metadata only EFFECT OF ANTIEPILEPTIC DRUGS ON ERYTHROCYTE OSMOTIC FRAGILITY AND LIPID-PEROXIDATION(ELSEVIER SCIENCE BV, 1994) YALÇIN, AHMET SUHA; YALCIN, AD; ONARAN, I; YALCIN, ASEpileptic children receiving antiepileptics were studied to investigate the effect of carbamazepine and phenobarbital therapy on erythrocyte osmotic fragility and lipid peroxidation. Significant differences between the two groups were observed in erythrocyte osmotic fragility. In addition, there was a significant increase in erythrocyte malondialdehyde release in the epileptic group compared to controls. It is suggested that the use of antioxidants in addition to antiepileptic drugs may be beneficial.Publication Metadata only EFFECT OF VERAPAMIL AND ILOPROST (ZK-36374) ON ENDOTHELIN RELEASE AFTER MESENTERIC ISCHEMIA-REPERFUSION INJURY(KARGER, 1994) YALÇIN, AHMET SUHA; YEGEN, C; AKTAN, AO; BUYUKGEBIZ, O; HAKLAR, G; YALCIN, AS; YALIN, R; ERCAN, SIn this experimental study we studied the effect of verapamil and iloprost on endothelin release in ischemia/reperfusion (IR) injury of the rat intestine. Endothelin levels in the portal blood and malondialdehyde (MDA), PGE2, and LTC4 levels in the intestinal tissue were determined. The MDA levels increased in the control group and this increase was reversed with iloprost, verapamil and both. The change in the LTC4 levels was insignificant between the groups. Iloprost reduced PGE2 and endothelin release, but verapamil was not as effective and no synergistic effect was encountered. The increased PGE2/LTC4 ratio was also reversed in the experimental groups, verapamil being less effective. Endothelin release seems to be related to both PGE2 levels and the PGE2/LTC4 ratio after mesenteric IR injury.Publication Metadata only Measurement of reactive oxygen species by chemiluminescence in diet-induced atherosclerosis: protective roles of vitamin E and probucol on different radical species(SPRINGER, 1998) YALÇIN, AHMET SUHA; Haklar, G; Sirikci, O; Ozer, NK; Yalcin, ASWe have investigated the effects of a high-cholesterol diet on the production of different reactive oxygen species in rabbit aortic rings and evaluated the protective effects of vitamin E and probucol in preventing peroxidative changes. Twenty-five male albino rabbits were divided into five groups. Control rabbits were fed a vitamin E-poor rabbit chow. Rabbits in the second group were given a vitamin E-poor diet supplemented with 2% cholesterol. Other groups received either 50 mg/kg vitamin E, 1% probucol, or both, in addition to 2% cholesterol for 4 weeks. Reactive oxygen species formation in aortic rings was measured by enhanced chemiluminescence using luminol and lucigenin. (The results were given as cpm/mg wet weight.) Further differentiation of radical species involved in luminol-enhanced chemiluminescence was performed using sodium azide and L-nitroarginine, a selective inhibitor of nitric oxide production. Our results indicated that cholesterol feeding increased lucigenin and luminol chemiluminescence, where the contribution of free radicals inhibited by sodium azide (radicals originating from endothelial cells or from phagocytes) were 53% and peroxynitrite 24%. Both vitamin E and probucol were effective as scavengers of free radicals, but the effect of vitamin E was more pronounced. In conclusion, the present study demonstrated excessive generation of reactive oxygen species within the atherosclerotic vessel. Peroxidative changes could be prevented by vitamin E and probucol treatment, but vitamin E seemed to be more efficient.Publication Metadata only Low dose MK-801 protects against iron-induced oxidative changes in a rat model of focal epilepsy(1998) YALÇIN, AHMET SUHA; Küçükkaya, B.; Aker, R.; Yüksel, M.; Onat, F.; Yalçin, A. S.We have used chemiluminescence measurements to examine the relationship between free radical formation and excitotoxicity in a post-traumatic epilepsy model. For this purpose, seven days after injecting iron in rat brain cortices, we measured luminol- and lucigenin-enhanced chemiluminescence in different brain regions (ipsilateral cortex, contralateral cortex, hypothalamus and hippocampus). In all brain regions (except contralateral cortices) both luminol- and lucigenin-enhanced chemiluminescence were increased in iron-injected group compared to saline-injected control group. These increases returned to control values in iron-injected rats pretreated with MK-801. Our results suggest that both free radicals and excitatory amino acids play important roles in the development of post-traumatic epilepsy and that MK-801 has protective effects against iron-induced chemiluminescence formation.