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 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 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 The role of reactive oxygen species and apoptosis in the pathogenesis of varicocele in a rat model and efficiency of vitamin E treatment(WILEY, 2004) YALÇIN, AHMET SUHA; Cam, K; Simsek, F; Yuksel, M; Turker, L; Haklar, G; Yalcin, S; Akdas, AWe investigated role of reactive oxygen species (ROS) and apoptosis in the pathogenesis of infertility in experimental model of varicocele. The protective effect of vitamin E was also examined. Three groups of rats were constructed as the first group had sham operation, experimental varicoceles were established by partial ligation of the left renal vein in later two groups. Third group had received vitamin E. Production of ROS was determined by chemiluminescence assay (CL). The in situ end labelling technique was utilized to investigate apoptosis. Tissue vitamin E levels were measured by high performance liquid chromatography. The differences between luminol enhanced CL levels of groups were not statistically significant. However, the difference between CL levels of lucigenin probe in left testicles of sham and varicocele groups were statistically significant (p = 0.0007). Similarly, the results of the third group receiving vitamin E significantly differed from the varicocele group (p = 0.0025). The difference of apoptotic index was also statistically significant between sham and varicocele groups (p = 0.0038). Although the values of apoptotic index detected in the vitamin E group were lower compared with the varicocele group, the difference was not significant. This study proposes that ROS production and apoptosis in the testicles were induced with experimental varicocele. Vitamin E had a protective role. An increased rate of apoptosis with experimental varicocele suggests a molecular alteration, which may involve ROS overproduction as the triggering mechanism. Consequently, this study indicates an association between varicocele and infertility at molecular level through stimulation of ROS and apoptosis.Publication Metadata only Evaluation of oxidant stress in chronic hemodialysis patients: use of different parameters(1995) YALÇIN, AHMET SUHA; Haklar, G.; Yeğenağa, I.; Yalçin, A. S.Patients with chronic renal failure, particularly those undergoing regular dialysis treatment (RDT) are candidates for free radical damage. It is difficult to quantitate free radicals because of their short half-lives and reactive nature. Therefore, indirect methods measuring products of lipid peroxidation and protein oxidation are preferred. The present study displays a profile of lipid peroxidation and protein oxidation parameters, which are more sensitive and specific than the widely used method measuring thiobarbituric acid reactive substances (TBARS), adapted to the plasma and erythrocyte samples of RDT patients. We have observed increased levels of plasma and erythrocyte lipid peroxidation and also demonstrated increased protein oxidation in erythrocyte membranes of RDT patients.Publication Metadata only Thyroxine prevents reoxygenation injury in isolated proximal tubule cells(SPRINGER, 2003) YALÇIN, AHMET SUHA; Erkan, E; Sakarcan, A; Haklar, G; Yalcin, SIschemia is characterized by cessation of blood flow and oxygen delivery to tissues that results in disruption of cellular structure and organelles. However, restoration of blood flow following ischemia causes reperfusion injury, characterized by further damage in the tissues mediated by reactive oxygen species. In the kidney, reactive oxygen molecules have been implicated in ischemic, toxic and immunological glomerular damage. Thyroxine has been shown to be cytoprotective in toxic and ischemic injury. Thyroxine's cytoprotective effect is postulated to be secondary to stimulation of intracellular ATP synthesis. However, the underlying mechanism of that beneficial effect remains to be investigated. In this study we investigated the effect of thyroxine (T4) on free oxygen radical production in an in vitro model of reperfusion injury. Free oxygen radical (FOR) levels were determined by a chemiluminescence method after freshly isolated rabbit proximal tubule cells were subjected to 15 min of anoxia followed by 45 min of reoxygenation. Reoxygenation injury resulted in a significant increase in FOR levels (P<0.0001). FOR levels were significantly lower in the group treated with thyroxine (P=0.01) and cells treated with thyroxine displayed better preservation of cellular structure. We conclude that thyroxine's cytoprotective effect might be via decreased synthesis of FOR, and thyroxine treatment may confer cytoprotection in renal conditions characterized by FOR-mediated injury.