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    Beneficial effects of melatonin on reperfusion injury in rat sciatic nerve
    (Wiley, 2004) Sayan, Hale; Özaçmak, Veysel Haktan; Özen, Oğuz Aslan; Coşkun, Ömer; Arslan, Seyfullah Oktay; Sezen, S. Cem
    Studies have shown that ischemia–reperfusion (I/R) produces free radicals leading to lipid peroxidation and to damage of the nervous tissue. Melatonin, a main secretory product of the pineal gland, has free radical scavenging and antioxidant properties and has been shown to diminish I/R injury in many tissues. There are a limited number of studies related to the effects of melatonin on I/R injury in the peripheral nervous system. Therefore, in the present study, the protective effect of melatonin was investigated in rats subjected to 2?hr of sciatic nerve ischemia followed by 3?hr of reperfusion. Following reperfusion, nerve tissue samples were collected for quantitative assesment of malondialdehyde (MDA), an oxidative stress marker, and superoxide dismutase (SOD), a principal antioxidant enzyme. Samples were further evaluated at electron microscopic level to examine the neuropathological changes. I/R elevated the concentration of MDA significantly while there was a reduction at SOD levels. Melatonin treatment reversed the I/R?induced increase and decrease in MDA and SOD levels, respectively. Furthermore, melatonin salvaged the nerve fibers from ischemic degeneration. Histopathologic findings in the samples of melatonin?treated animals indicated less edema and less damage to the myelin sheaths and axons than those observed in the control samples. Our results suggest that administration of melatonin protects the sciatic nerve from I/R injury, which may be attributed to its antioxidant property.
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    Erythropoietin stimulates wound healing and angiogenesis in mice
    (Taylor and Francis Online, 2006) Sayan, Hale; Özaçmak, Veysel Haktan; Güven, Aysel; Özaçmak, İhsan Diler
    Erythropoietin exerts hematopoietic effects by stimulating proliferation of early erythroid precursors. Nonhematopoietic effects of erythropoietin have also been shown. It may act as a new angiogenic factor in wound healing. This study aimed to investigate the effect of systemic administration of recombinant human erythropoietin on wound healing in mice. Dorsal incisional wounds were performed in mice, which were then divided into two groups; a group treated for 7 days with recombinant human erythropoietin, and a control group. Sacrificing animals on day 7, the wound tissues were collected for analysis of wound breaking strength, malondialdehyde, a marker of lipid peroxidation, hydroxyproline, an index of reparative collagen deposition, reduced glutathione levels, and for histological evaluation. The immunohistochemical determination of vascular endothelial growth factor (VEGF) which is believed to be the most prevalent angiogenic factor throughout the skin repair process, was also studied. The treatment significantly increased wound breaking strength by decreasing malondialdehyde and increasing hydroxyproline levels on day 7 after wounding. No statistically meaningful change was observed in reduced glutathione content. VEGF was immunostained significantly more on wound tissue of treated animals compared to the control group. Recombinant human erythropoietin treatment may be effective in wound healing due to inhibition of lipid peroxidation, deposition of collagen, and VEGF expression in wound area.
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    Protective effects of L-arginine on rat terminal ileum subjected to ischemia/reperfusion
    (WoltersKluwer, 2008) Sayan, Hale; Özaçmak, Veysel Haktan; Altaner, Şemsi; Arslan, Seyfullah Oktay
    Studies have shown that nitric oxide (NO) may play a major role in sustaining mucosal integrity; however, NO has been also implicated in the pathogenesis of ischemia/reperfusion (I/R)–related tissue injury. We investigated the effects of L-arginine and NG-nitro L-arginine methyl ester (L-NAME) on the acetylcholine-induced contractile response of ileum and the levels of malondialdehyde (MDA) and reduced glutathione (GSH). Histopathological changes were also evaluated in ileal preparations.