Person: ATASOY, BESTE MELEK
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ATASOY
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BESTE MELEK
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Publication Open Access Propylthiouracil-induced hypothyroidism protects ionizing radiation-induced multiple organ damage in rats(BIOSCIENTIFICA LTD, 2006-05) VELİOĞLU ÖĞÜNÇ, AYLİZ; Sener, G.; Kabasakal, L.; Atasoy, B. M.; Erzik, C.; Velioglu-Ogunc, A.; Cetinel, S.; Contuk, G.; Gedik, N.; Yegen, B. C.The objective of this study was to examine the potential radioprotective properties of propylthiouracil (PTU)-induced hypothyroidism against oxidative organ damage induced by irradiation. Sprague-Dawley rats were pre-treated with saline or PTU (10 mg/kg i.p.) for 15 days, and were then exposed to whole-body irradiation (800 cGy). A group of rats were decapitated at 6 h after exposure to irradiation, while another group was followed for 72 h after irradiation, during which saline or PTU injections were repeated once daily. Lung, liver, kidney and ileum samples were obtained for the determination of malondialdehyde (MDA; an index of lipid peroxidation) and glutathione (GSH, an antioxidant) levels, myeloperoxidase activity (MPO; an index of tissue neutrophil accumulation) and collagen contents, while oxidant-induced DNA fragmentation was evaluated in the ileal tissues. All tissues were also examined microscopically and assayed for the production of reactive oxidants using chemiluminescence (CL). Lactate dehydrogenase (LDH), an indicator of tissue damage, and turnout necrosis factor-alpha (TNF alpha) were assayed in serum samples. Irradiation caused a significant decrease in GSH level, which was accompanied by significant increases in MDA levels, MPO activity, CL levels and collagen content of the tissues studied (P < 0.05-0.001). Similarly, serum TNFa and LDH were elevated in the irradiated rats as compared with the control group. On the other hand, PTU treatment reversed all these biochemical indices, as well as histopathological alterations induced by irradiation. Our results suggested that PTU-induced hypothyroidism reduces oxidative damage in the lung, hepatic, renal and ileal tissues probably due to hypometabolism, which is associated with decreased production of reactive oxygen metabolites and enhancement of antioxidant mechanisms.Publication Metadata only Ginkgo biloba extract protects against ionizing radiation-induced oxidative organ damage in rats(ACADEMIC PRESS LTD ELSEVIER SCIENCE LTD, 2006) VELİOĞLU ÖĞÜNÇ, AYLİZ; Sener, G; Kabasakal, L; Atasoy, BM; Erzik, C; Velioglu-Ogunc, A; Cetinel, U; Gedik, N; Yegen, BCThe present study was designed to determine the possible protective effects of Ginkgo biloba extract (EGb) against oxidative organ damage induced by irradiation (IR). Sprague-Dawley rats were exposed to whole-body IR (800cGy) after a 15-day pretreatment with either saline or EGb (50 mg/kg/day), intraperitoneally, and treatments were repeated immediately after the IR. Then the rats were decapitated at either 6 h or 72 It after IR, where EGb or saline injections were repeated once daily. Lung, liver, kidney and ileum samples were obtained for the determination of malondialdehyde, glutathione levels, myeloperoxidase activity and collagen contents, while oxidant-induced DNA fragmentation was evaluated in the ileal tissues. All tissues were also examined microscopically and assayed for the production of reactive oxidants using chemiluminescence (CL). Lactate dehydrogenase (LDH)-an indicator of tissue damage and TNF-alpha were assayed in serum samples. In the saline-treated irradiation groups, glutathione levels were decreased significantly, while the malondialdehyde levels, myeloperoxidase activity and collagen content were increased in the tissues (p < 0.01-0.001), which were in parallel with the increases in luminol and lucigenin CL values. In the EGb treated-IR groups, all of these oxidant responses were prevented significantly (p < 0.05-0.01). LDH and TNF-alpha levels, which were increased significantly (p < 0.01-0.001) following IR, were decreased (p < 0.05-0.001) with EGb treatment. In conclusion, the present data demonstrate that EGb, through its free radical scavenging and antioxidant properties, attenuates irradiation-induced oxidative organ injury, suggesting that EGb may have a potential benefit in enhancing the success of radiotherapy. (c) 2005 Elsevier Ltd. All rights reserved.Publication Open Access Radiation-induced oxidative injury of the ileum and colon is alleviated by glucagon-like peptide-1 and -2(ELSEVIER SCIENCE BV, 2015-04) ATASOY, BESTE MELEK; Deniz, Mustafa; Atasoy, Beste M.; Dane, Faysal; Can, Guray; Erzik, Can; Cetinel, Sule; Yegen, Berrak C.Purpose: The present study was conducted to characterize the possible therapeutic effects of glucagon-like peptide (GLP)-1 and GLP-2 against oxidative damage in the ileum and colon of irradiated rats. Methods and materials: Sprague-Dawley rats of both sexes received either a single dose of GLP-1 (0.1 nmol/kg, intraperitoneally, ip; n = 6) 10 min before abdominal irradiation (IR) or two consecutive doses of GLP-2 (7 nmol/kg, ip; n = 6) at 30 and 10 min before IR, while another group was administered vehicle (n = 6) 10 min before IR. Control rats (n = 6) received vehicle treatment without IR. On the fourth day of IR, samples from ileum and colon were removed for histological analysis, for the determination of myeloperoxidase (MPO) activity, malondialdehyde (MDA) and glutathione (GSH) levels, as well as DNA fragmentation ratio, an index of apoptosis. Results: IR-induced oxidative injury in the colonic tissue of vehicle-treated rats, evidenced by elevated MDA levels and MPO activity, as well as depleted colonic GSH levels, was reversed by GLP-2, while GLP-1 reduced IR-induced elevations in colonic MDA levels. IR-induced injury with elevated ileal MDA levels was reduced by GLP-1, while replenishment in GSH was observed in GLP-2-treated rats. Conclusion: Current findings suggest that GLP-1 and GLP-2 appear to have protective roles in the irradiation-induced oxidative damage of the gut by inhibiting neutrophil infiltration and subsequent activation of inflammatory mediators that induce lipid peroxidation. Copyright (C) 2015, The Egyptian Society of Radiation Sciences and Applications. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license.Publication Metadata only Prophylactic feeding with immune-enhanced diet ameliorates chemoradiation-induced gastrointestinal injury in rats(TAYLOR & FRANCIS LTD, 2010) ATASOY, BESTE MELEK; Atasoy, Beste M.; Deniz, Mustafa; Dane, Faysal; Ozen, Zeynep; Turan, Pinar; Ercan, Feriha; Cerikcioglu, Nilguen; Aral, Cenk; Akgun, Zueleyha; Abacioglu, Ufuk; Yegen, Berrak C.Materials and methods: Forty-eight Sprague-Dawley rats were divided into control (C, n = 6), irradiation (IR, n = 14), fluoropyrimidine (5-FU, n = 14)-treated, IR + 5-FU (n = 14)-treated groups. Half of each irradiated and/or 5-FU-treated groups were previously fed with IED containing arginine, omega-3-fatty acids and RNA fragments, while the other half were fed a standard rat diet (SD) for eight days before the induction of IR or injection of 5-FU. In IR groups, whole abdominal irradiation (11 Gy) was performed with 6 MV photons. In the 5-FU groups, fluoropyrimidine (100 mg/kg) was administered intraperitoneally 30 min prior to irradiation. All animals were sacrificed on the 4th day of IR or 5-FU injection. Results: Bacterial colony counts in the ceca and mesenteric lymph nodes of IED-fed rats, which have received either 5-FU and/or irradiation were significantly lower than the corresponding SD-fed groups. Morphometric results revealed that gastric, ileal and colonic injuries were less in IED-treated IR or IR + 5-FU + IED groups, as compared to SD-fed groups. However, IED did not alter DNA fragmentation ratios. Conclusion: Prophylactic feeding of IED has a protective effect on chemoradiation-induced gastrointestinal injury, which appears to involve the eradication of bacterial overgrowth.Publication Metadata only Melatonin ameliorates ionizing radiation-induced oxidative organ damage in rats(PERGAMON-ELSEVIER SCIENCE LTD, 2003) ATASOY, BESTE MELEK; Sener, G; Jahovic, N; Tosun, O; Atasoy, BM; Yegen, BCThis study was designed to study the effects of the potential radioprotective properties of pharmacological doses of melatonin against organ damage induced by whole-body irradiation (IR) in rats. A total of 32 male Sprague-Dawley rats were exposed to irradiation performed with a LINAC producing 6 MV photons at a focus 100 cm distant from the skin. Under ketamine anaesthesia, each rat received a single whole-body dose of 800 cGy. Immediately before and after IR, rats were treated with either saline or melatonin (20 mg/kg and 10 mg/kg, ip) and decapitated at 12-h after exposure to irradiation. Another group of rats was followed for 72-h after IR, where melatonin (10 mg/kg, ip) injections were repeated once daily. Tissue levels of malondialdehyde (MDA)an index of lipid peroxidation-, glutathione (GSH)-a key to antioxidant- and myeloperoxidase (MPO) activity-an index of neutrophil infiltration-were estimated in liver, lung, colon and intestinal tissues. The results demonstrate that both 12-h and 72-h following IR, tissue leves of MDA were elevated (p<0.05-0.001), while GSH levels were reduced (p<0.05-0.001) in all organs. On the other hand, melatonin, reduced the levels of MDA and increased the GSH levels significantly, (p<0.05-0.001). MPO activity was increased significantly in the colonic tissue at the both 12-h and 72-h, and in the hepatic tissue at the 72-h following IR, which were reduced by melatonin (p<0.01-0.001). In the lung tissue enzyme activity was decreased at 72nd h of postirradiation. In conclusion, the increase in MDA levels and MPO activity and the concomitant decrease in GSH levels demonstrate the role of oxidative mechanisms in irradiation-induced tissue damage, and melatonin, by its free radical scavenging and antioxidant properties, ameliorates irradiation-induced organ injury. Thus, supplementing cancer patients with adjuvant therapy of melatonin may have some benefit for successful radiotherapy. (C) 2003 Elsevier Inc. All rights reserved.