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Öğe Cytotoxicity in cytokine stimulated astrocyte cultures: Role of IL-6 and nitric oxide(John Wiley & Sons Ltd, 2004) Yilmaz, O; Taskiran, D; Aydar, SThe cytokines interleukin 1 (IL-1) and tumor necrosis factor alpha (TNF-alpha), produced by glial cells within the brain, appear to contribute to the neuropathogenesis of several inflammatory neurodegenerative diseases. However, little is known about the mechanism underlying cytokine-induced neurotoxicity. Using astroglial cultures obtained from fetal rat brain, we investigated the effects of lipopolysacchanides (LPS) and cytokines (IL-1beta and TNF-alpha). Primary cell cultures treated with LPS, IL-1beta plus TNF-alpha generated substantial amounts of nitric oxide (NO), elevated interleukin 6 (IL-6) levels and caused astroglial injury measured by lactate dehydrogenase (LDH) activity. However, blockade of NO production with nitric oxide synthase (NOS) inhibitors did not affect cell death, suggesting that NO is not responsible for cytokine-induced astroglial cell death under the experimental conditions employed.Öğe Effects of acidosis on viability of glial cells(Blackwell Science Ltd, 1998) Yilmaz, O; Hariri, NIÖğe Effects of nicotine on active avoidance learning in rats: Sex differences(Lippincott Williams & Wilkins, 1997) Yilmaz, O; Kanit, L; Okur, BE; Pogun, SNicotine, a cognition enhancer and a drug of abuse, exerts its central actions through neuronal nicotinic acetylcholine receptors which show sexual dimorphism. This study tested the effects of nicotine on active avoidance learning in male and female rats. Three month-old Sprague-Dawley rats received varying doses of nicotine (0.2, 0.4 and 0.6 mg/kg) or saline s.c. before active avoidance learning trials (15 trials/day) for a period of 5 days. Behavioural testing was continued after the termination of nicotine treatment once a week for four weeks. Nicotine improved acquisition of active avoidance learning in a dose-dependent manner. fn male rats nicotine was active at all doses tested whereas, in females, learning performance deteriorated at a dose of 0.6 mg/kg. In conclusion, nicotine pre-treatment affects active avoidance in a sexually dimorphic and dose-dependent manner.Öğe Evaluation of association between hepatitis A and Helicobacter pylori infections and routes of transmission(Turkish J Pediatrics, 2006) Egemen, A; Yilmaz, O; Akil, I; Altuglu, IPrevious research about coexistence of Helicobacter pylori (HP) and hepatitis A virus (HAV) infections and the factors that increase their prevalence has suggested that the route of transmission of HP infection includes oral-oral and water-foods as well as the fecal-oral route. The aim of this study was to evaluate the routes of transmission of HP by comparing the seroprevalences of HP and HAV in children. One hundred and two children aged 1-18 years living in rural and urban regions of izmir were included in this study. Anti-HP IgG and anti-HAV IgG antibodies were measured via enzyme immunoassay method. Seropositivities for HP and HAV were 56.8% and 51.9%, respectively. Seroprevalence for both infections increased with increasing age. However, a significant difference could not be detected between rural and urban areas. Sex did not have a significant effect. There was no infection in 22.1% of children, while 30.8% had both of the infections. 21.1% were positive only for HAV while 26% were positive only for HP. No significant correlation between seroprevalences of HP and HAV was detected. This study suggests the existence of various other routes of transmission of HP apart from the fecal-oral route.Öğe Evaluation of the tissue distribution of creatinine and of the potential of frosemide to eliminate creatinine from the tissues in rats with ablation nephropathy given technetium 99m-labelled creatinine(Oxford Univ Press, 2005) Lambrecht, FY; Kavukcu, S; Yilmaz, O; Durkan, K; Soylu, AÖğe Frequency of gastroesophageal reflux disease in nonatopic children with asthma-like airway disease(W B Saunders Co Ltd, 2006) Yuksel, H; Yilmaz, O; Kirmaz, C; Aydogdu, S; Kasirga, EGastroesophageal reflux disease (GERD) is commonly associated with asthma; however, frequency in nonatopic children with asthmatic symptoms is unknown. The aim of this study was to determine the frequency of gastroesophageal reflux (GER) in nonatopic children with asthma-like airway disease that recur despite conventional asthma treatment and to evaluate the clinical response to lansoprazole treatment. Twent-five nonatopic children aged between 1 and 16 years who have asthma-like airway disease and 25 healthy children were included in the study. All cases underwent 24h pH monitoring with dual. sensor catheters. Additionally, acid suppressor treatment was administered to patients diagnosed as having GERD and clinical response was evaluated. Major symptoms encountered in the patient group included wheezing and cough (88%, and 32%, respectively). Reflux episodes were more common in distal esophagus during the prone position (reflux index (RI) of 11.5 +/- 10.3 vs. 16.2 +/- 9.4 during supine vs. prone). ALL distal esophageal parameters were significantly higher in the patient group except number of reflux episodes lasting longer than 5 min (RI of 13.3 +/- 13.1 vs. 3.9 +/- 2.9 in the patient vs. control groups, respectively). There was a significant improvement in symptoms and requirement for medication with treatment (number of systems decreased from 2.3 +/- 0.6 to 0.4 +/- 0.6, P = 0.00). In conclusion, GERD is significantly more common in nonatopic children with asthma-Like airway disease compared to the controls and clinical improvement is significant after acid suppressor treatment. Thus, we suggest that children followed-up with the diagnosis of nonatopic asthma with recurrent exacerbations despite adequate asthma treatment have a high frequency of GER and that Lansoprazole treatment may be considered early in management. (c) 2005 Elsevier Ltd. All rights reserved.Öğe Intersession interval affects performance in the Morris Water Maze(Gordon Breach Sci Publ Ltd, 1998) Kanit, L; Yilmaz, O; Taskiran, D; Balkan, B; Furedy, JJ; Pogun, SWe have recently reported an effect that shows a sexually dimorphic difference in cognitive style rather than ability. The preparation for potentially producing this proximal perceptual style effect is one where rats are first given 4-trial daily acquisition sessions for 12 days with the platform always in the same position, but sometimes visible (perceptual, "look-out" condition) and sometimes hidden (conceptual, "navigational" condition). On the first, probe trial of the 13th day, the platform's position is shifted to a point very close (proximal) to the rat's starting position, and made visible. The proximal perceptual style (PPS) effect has emerged sexually dimorphically in that only females swam straight to the newly positioned proximal platform. Other studies have shown that the PPS effect is eliminated (with Females behaving like males) by nicotine and prepubertal ovariectomy, and does not occur in prepubertal females. Also, as no sex-related effects emerged during acquisition during these studies, the PPS effect appears to be a function of cognitive style rather than ability. The present study varied age, and, in an effort to economize on time, shortened acquisition to 6 days by having morning and afternoon sessions each day. To our surprise, this relatively subtle psychological manipulation eliminated the PPS effect, and also yielded some sex- and age-related effects during acquisition: A male advantage was observed and prepubertal rats had longer escape latencies; there was no significant interaction between sex and age.Öğe Nicotine modulates nitric oxide in rat brain(Elsevier Science Bv, 2000) Pogun, S; Demirgoren, S; Taskiran, D; Kanit, L; Yilmaz, O; Koylu, EO; Balkan, B; London, EDNicotine exerts its central actions by regulating cationic fluxes through nicotinic acetylcholine receptors (nAChRs). By this effect, the drug likely also modifies events occurring beyond the nAChR, including the regulation of nitric oxide (NO) synthesis. The present study was undertaken to assess the effects of acute and chronic nicotine administration (0.4 mg/kg, s.c.) on levels of NO2- + NO3- stable metabolites of NO, in brain regions of male and female rats. Nicotine increased levels of the metabolites, and therefore presumably of NO, with sex differences in the degree of stimulation, the brain regions affected, and the variance between the effects of acute and chronic administration. Prior inhibition of NO synthase eliminated the effect of nicotine in all regions studied. While nicotine appeared to increase NO indirectly via glutamate receptors in the cortex and hippocampus, this was not true of the corpus striatum, where blocking NMDA-type glutamate receptors with MK-801 had no effect. The findings support the view that NO is likely involved in some of the central effects of nicotine. (C) 2000 Elsevier Science BN. All rights reserved.Öğe Nitric oxide synthetase inhibition hinders facilitation of active avoidance learning by nicotine in rats(Lippincott Williams & Wilkins, 2000) Yilmaz, O; Kanit, L; Okur, BE; London, ED; Pogun, SNicotine produces dose-dependent enhancement of performance in an active avoidance test, and also increases the levels of NO2- and NO3-, which are stable metabolites of nitric oxide (NO), in various brain regions of rats. On the basis of these two observations, we hypothesized that the beneficial effect of nicotine on learning could result from increased NO in relevant brain regions. We therefore tested active avoidance performance in rats given L-N-omega-nitroarginine (L-NA) to inhibit NO synthetase (NOS) prior to nicotine administration, Male Sprague-Dawley rats received L-NA (30 or 50 mg/kg), nicotine (0.4 mg/kg), saline or combinations of these treatments before learning trials. Rats were also tested on the inclined plane, to assess the possible effects due to impairment of motor function by drug treatments on active avoidance learning. L-NA treatment impaired the acquisition of active avoidance learning, and this defect was partially overcome by the co-administration of nicotine. Nicotine facilitated learning and significantly increased the number of correct responses. The threshold for the effect of NOS inhibition on performance exceeded 30 mg/kg L-NA, whereas 50 mg/kg impaired learning and also eliminated the nicotine-induced enhancement of learning. On the fifth day of learning trials, no facilitation of learning by nicotine was observed in rats receiving either dose of L-NA. Our results suggest that NO is involved in the facilitation of active avoidance learning by nicotine. (C) 2000 Lippincott Williams & Wilkins.Öğe Serum tumor growth factor-beta 1 levels in patients with cirrhosis, chronic hepatitis B and chronic hepatitis C(John Libbey Eurotext Ltd, 2004) Kirmaz, C; Terzioglu, E; Topalak, O; Bayrak, P; Yilmaz, O; Ersoz, G; Sebik, FChronic liver disease and cirrhosis are two of the most important health problems according to current gastroenterology literature. Based on the recent developments in the field of immunology, advanced follow-up and treatment modalities have been introduced for these disorders. Immune defence against viral infections depends on effective cellular immune responses derived mainly from Th1-related cytokines. Th2 type immune responses can inhibit efficient immune function by secretion of several cytokines such as IL-10, TGF-beta1. In this particular study, we determined the serum levels of TGF-beta1, which plays a role in immune suppression and induction of tissue fibrosis. We evaluated the role of TGF-beta1 in the pathogenesis of chronic liver disease and cirrhosis. Fourteen chronic hepatitis B (CHB), 12 chronic hepatitis C (CHC) patients and 21 cirrhotic patients were enrolled in the study. The control group consisted of ten healthy people. Serum TGF-beta1 levels were higher in both cirrhosis and CHC group when compared to those in CHB and control groups (P < 0.05). Although serum TGF-beta1 levels in the cirrhosis group were higher than that in the CHC group, the difference was not statistically significant. In conclusion, elevated TGF-beta1 levels in patients with CHC and cirrhosis may have a role in the pathogenesis and chronicity of these diseases.Öğe Sexually dimorphic cognitive style, female sex hormones, and cortical nitric oxide(Pergamon-Elsevier Science Ltd, 2000) Kanit, L; Yilmaz, O; Taskiran, D; Kulali, B; Furedy, JJ; Demirgoren, S; Pogun, SRecent studies using the water maze (WM) found marked sex differences in behavioral strategy employed in place learning tasks in adult rats. When a change in the platform position is introduced following learning the place of a platform (visible or hidden) in a different position, female rats escape to the newly positioned visible platform faster than males. Nitric oxide (NO) is implicated in place learning, and there are regional sex differences in its stable metabolites, NO2- +NO3- in rat brain. Furthermore, NO2- + NO3- levels are sensitive to ovariectomy in female rats. The effect of sex hormones on brain development and function is well documented. The present study was undertaken to study the effects of ovariectomy and hormonal manipulations on cognitive performance in a WM task designed to test differences in behavioral strategy in Sprague-Dawley rats (n = 48) of both sexes. Some of the females rats were ovariectomised and received either hormone replacement (estrogen or progesterone alone or in combination) or the vehicle. Cortical and hippocampal NO2- + NO3- levels were determined after behavioral testing. There were no group differences in cognitive ability or non-cognitive factors such as motivation or swim speed. Males and intact females differed in their cognitive style, but hormonal manipulations in female rats did not affect this relative use of behavioral strategy. There was a correlation between performance on the trial where sex differences were most prominent and NO2- + NO3- levels in the cortex. Our results suggest that the activational effects of circulating gonadal hormones do not play a major role in sexually dimorphic cognitive styles. (C) 2000 Elsevier Science Inc. All rights reserved.