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Öğe Effects of iloprost and piracetam in spinal cord ischemia-reperfusion injury in the rabbit(NATURE PUBLISHING GROUP, 2011) Kalkan, E.; Keskin, F.; Kaya, B.; Esen, H.; Tosun, M.; Kalkan, S. S.; Erdi, F.Study design: Experimental Study. Objectives: The aim of this study was to investigate the neuroprotective effects of iloprost and piracetam on spinal cord ischemia/reperfusion (I/R) injury in the rabbit. Settings: The Experimental Research Center of Selcuk University, Konya, Turkey. Methods: A total of 24 rabbits were divided into four groups of six rabbits each, as follows: group 1 (n = 6) sham, laparotomy only; group 2 (n = 6) I/R; group 3 (n = 6) I/R + iloprost; and group 4 (n = 6) I/R + piracetam. I/R was established in groups 2, 3 and 4. Subsequently, they were followed up neurologically for 24 h until the rabbits were killed; biochemical and histopathological examinations of samples from the spinal cord were carried out. Results: Neurological examination results were significantly better in the iloprost and piracetam groups compared with the I/R group (P<0.05). Neuroprotection was achieved with iloprost and piracetam by suppressing malondialdehyde (P<0.05), increasing glutathione peroxidase activity (P<0.05) and decreasing the xanthine oxidase level. In histopathological assessment, iloprost and piracetam groups were statistically different from the I/R group in terms of the number of apoptotic neurons in gray matter and white matter, as well as in terms of degenerated neurons and glial cells (P<0.05). No statistical difference was determined between the four groups in the number of degenerated glial cells (P>0.05). Conclusion: This study has shown that iloprost and piracetam have neuroprotective effects in I/R injury both neurologically and histopathologically because of inhibition of lipid peroxidation. Spinal Cord (2011) 49, 81-86; doi: 10.1038/sc.2010.76; published online 29 June 2010Öğe The effects of prophylactic zinc and melatonin application on experimental spinal cord ischemia-reperfusion injury in rabbits: experimental study(NATURE PUBLISHING GROUP, 2007) Kalkan, E.; Çiçek, O.; Ünlü, Ali; Abuşoğlu, Sedat; Kalkan, S. S.; Avunduk, M. C.; Baysefer, A.Study design: Experimental study. Objectives: To determine the neuroprotective effects of zinc and melatonin on spinal cord ischemia-reperfusion (I/R) injuries of rabbits. Setting: The Experimental Research Centre of Selcuk University, Konya, Turkey. Methods: Twenty-four male rabbits underwent spinal cord ischemia by clamping the thoraco-abdominal aorta for 20 min. Twenty-minutes before the aortic clamping, animals received zinc, melatonin or a combination of both. Neurological examination of the animals was performed three times during reperfusion period. The animals were killed 24 h after reperfusion. Spinal cord samples were taken for biochemical and histopathological evaluation. Results: Pre-treated animals with zinc, melatonin or combination displayed better neurological outcomes than the I/R group (P < 0.05). Zinc, melatonin and combined treatment prevented spinal cord injury by reducing apoptosis rate (P < 0.05) and preserving intact ganglion cell numbers (P < 0.05). Zinc pre-treatment protected spinal cord by preventing malondialdehyde (MDA) formation (P = 0.002), increasing glutathione peroxidase (GPx) activity(P = 0.002) and decreasing xanthine oxidase enzyme activity (P = 0.026) at molecular level. Melatonin treatment also resulted with MDA formation (P = 0.002), increased GPx activity (P = 0.002) and decreased xanthine oxidase activity(P = 0.026). Conclusion: The results of the study showed that prophylactic zinc and melatonin use in spinal cord I/R not only suppressed lipid peroxidation by activating antioxidant systems but also had significant neuroprotective effects by specifically improving the neurological and histopathological situation.Öğe Failure mechanism of shear-wall dominant multi-story buildings(WIT PRESS/COMPUTATIONAL MECHANICS PUBLICATIONS, 2008) Yuksel, S. B.; Kalkan, E.The recent trend in the building industry of Turkey as well as in many European countries is towards utilizing the tunnel form (shear-wall dominant) construction system for development of multi-story residential units. The tunnel form buildings diverge from other conventional reinforced concrete (RC) buildings due to the lack of beams and columns in their structural integrity. The vertical load-carrying members of these buildings are the structural-walls only, and the floor system is a flat plate. Besides the constructive advantages, tunnel form buildings provide superior seismic performance compared to conventional RC frame and dual systems as observed during the recent devastating earthquakes in Turkey (1999 M-w 7.4 Kocaeli, M-w 7.2 Duzce, and 2004 M-w 6.5 Bingol). With its proven earthquake performance, the tunnel form system is becoming the primary construction technique in many seismically active regions. In this study, a series of nonlinear analyses were conducted using finite element (FE) models to augment our understanding on their failure mechanism under lateral forces. In order to represent the nonlinear behavior adequately, The FE models were verified with the results of experimental studies performed on three dimensional (M) scaled tunnel form building specimens. The results of this study indicate that the structural walls of tunnel form buildings may exhibit brittle flexural failure under lateral loading, if they are not properly reinforced. The global tension/compression couple triggers this failure mechanism by creating pure axial tension in the outermost shear-walls.Öğe Intradural Intramedullary Conus Medullaris Metastasis of Colorectal Adenocarcinoma: A Case Report(Journal Neurological Sciences, 2012) Keskin, F.; Kalkan, E.; Erdi, M. F.; Esen, H.Spinal cord metastasis is rarely seen. Intramedullary spinal metastasis has been defined between the rates of 0,9 -2,1% in the autopsies performed on the cancerous cases. And also intramedullary spinal metastases are defined at a rate of 8,5% in the cases which have metastasis at central nervous system. The male patient, who was at the age of 62, was admitted to our clinic with the complaints of serious back and left leg pain and weakness at the left leg which had begun 15 days before. Low anterior resection + total mesorectal excision + ileostomy were applied to the patient five years ago due to colorectal adenocarcinoma. The carcinoma was reported as adenocarcinoma grade II. Chemotherapy and radiotherapy were applied after postoperative period. Left SLR was positive and 3/5 monoparesis at left leg was determined in the patients neurological examination. Conus medullaris located tumor was determined in the magnetic resonance imaging of the patient. Intradural intramedullary tumor which was infiltrated to the conus medullaris was totally removed with microneurosurgical technique via Th12-L1-2 total laminectomy. Th11-L3 posterior instrumentation and fusion were added because of expansive laminectomy and L1 corpus involvement of the tumor. The histopathological examination was reported as colorectal adenocarcinoma metastasis. In this manuscript we report a colorectal adenocarcinoma metastasis to the conus medullaris for the first time in the literature. Key words: Colorectal adenocarcinoma, conus medullaris, metastasis, surgery
