Browsing by Author "Ekerbiçer, N"

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    The Histologic Evaluation of Atorvastatin and Melatonin Treatment on Oxidative Stress and Apoptosis of Diabetic Rat Pancreas
    Gürpinar, T; Ekerbiçer, N; Uysal, N; Barut, T; Tarakçi, F; Tuglu, MI
    In the diabetic state, there is an enhanced oxidative stress due to excessive production of reactive oxygen compounds and decreased bioavailability of nitric oxide. Antioxidant treatment has been used to prevent oxidative damage in diabetes. The objective of the present study was to explore the effects of atorvastatin (AT) and melatonin (MLT) on oxidative stress in diabetic rat pancreas. We also assessed nitric oxide synthase (NOS) activity and apoptosis. Diabetes was induced by an alkylating agent steptozotocin (STZ, 55 mg/kg, IP). Six weeks later rats were divided into five groups: STZ-induced diabetic group received atorvastatin (STZ+AT), STZ-induced diabetic group received melatonin (STZ+MLT) and STZ-induced diabetic group received atorvastatin and melatonin (STZ+AT+MLT). The vehicle-treated non-diabetic (CT) and diabetic group (STZ-CT) served as normoglycemic and diabetic controls. AT was given 8 mg/kg orally and MLT was given 10 mg/kg/IP once a day for 2 weeks beginning from the sixth week. Pancreatic tissue was examined by immunohistochemical methods. Although no significant difference was observed with respect to antioxidant status, NOS activity was tended to be higher in the untreated diabetic rats than in the treated rats. We observed that AT and MLT treatment improved the histopathological changes including apoptosis and oxidative stress in diabetic pancreas.
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    Effects of JWH-018, A New Synthetic Cannabinoid on Hemodynamics, Histopathology and Behavior of Rats
    Sen, G; Tozduman, B; Tuglu, MI; Cöllü, F; Demet, MM; Kutlu, N; Çavusoglu, TG; Ekerbiçer, N
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    Damage Mechanisms in Rat Brain for JWH-018 from New Synthetic Cannabinoids
    Sen, G; Tozduman, B; Ekerbiçer, N; Çöllü, F; Temel, M; Demet, MM; Kutlu, N; Çavusoglu, TG; Tuglu, MI
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    Statin treatment reduces oxidative stress-associated apoptosis of sciatic nerve in diabetes mellitus
    Gürpinar, T; Ekerbiçer, N; Harzadin, NU; Barut, T; Tarakçi, F; Tuglu, MI
    Statins are lipid-lowering drugs that are widely used for treating hyperlipidemia, especially in diabetic patients. The aim of our study was to explore the effects of atorvastatin on oxidative stress and apoptosis in the sciatic nerve due to hyperglycemia. Diabetes was induced by streptozotocin. Atorvastatin was given orally for two weeks beginning from the sixth week. Microscopic examination of sciatic nerve revealed that normal tissue organization was disrupted in streptozotocin induced diabetic rats. Treatment with Atorvastatin reduced the histological damage and protected the morphological integrity of the sciatic nerve in streptozotocin induced diabetes. Increased expressions of transforming growth factor beta-1, endothelial nitric oxide synthase and TUNEL in sciatic nerve from streptozotocin induced diabetes were reduced by Atorvastatin. Atorvastatin could improve the effects of oxidative stress and apoptosis on the sciatic nerve due to diabetes.
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    Sensitively recorded breathing signals of rats and their nonlinear dynamics
    Zeren, T; Özbek, M; Ekerbiçer, N; Yalçin, GÇ; Akdeniz, KG
    Nonlinear dynamical properties of sensitively recorded breathing signals (SRBS), which include cardiac induced air flow pulsations so-called pneumocardiogram (PNCG) signals, are investigated, in this methodological study. For this purpose, we assessed the SRBS of laboratory rat. The nonlinear behaviors of SRBS were investigated by the reconstructing phase space, using the autocorrelation function and the false nearest neighbor method. The chaotic SRBS attractors were discussed from the point of view of the cardiopulmonary system. This method can be used to assess the heart performance and respiratory mechanics, and might be useful to design for the physiological studies of cardiorespiratory system in small laboratory animals. (C) 2007 Elsevier B.V. All rights reserved.
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    The Effects of the Melatonin Treatment on the Oxidative Stress and Apoptosis in Diabetic Eye and Brain
    Gürpinar, T; Ekerbiçer, N; Uysal, N; Barut, T; Tarakçi, F; Tuglu, MI
    Oxidative stress plays an important role in the development of complications in diabetes mellitus. Antioxidant therapy has been thought to decrease oxidative stress. The objective of the present study was to explore the effects of melatonin (MLT) on oxidative stress in diabetic rat eye and brain tissue by using immunohistochemical methods. Diabetes was induced by streptozotocin, (STZ, 55 mg/kg/i.p) in adult rats. MLT was given 10 mg/kg/i.p once a day for 2 weeks beginning from the sixth week. Six weeks later, rats were divided into three groups: control (CR), STZ-induced diabetic (STZ), and STZ-induced diabetic group received melatonin (STZ+MLT). Although no significant difference was observed with respect to antioxidant status, NOS activity tended to be higher in the untreated diabetic rats than in the treated rats. It was observed that MLT treatment improved the histopathological changes including apoptosis and oxidative stress in brain and eye in diabetic rat.
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    A physical model of the thermodilution method: influences of the variations of experimental setup on the accuracy of flow rate estimation
    Özbek, M; Özel, HF; Ekerbiçer, N; Zeren, T
    The thermodilution method has been widely used to estimate cardiac output by injecting a cold solution into circulating blood. It is uncertain if radial heat transfer from the vascular/cardiac wall to circulating injectate can cause inaccurate results with this method. In this study, we have introduced a physical experimental model of the thermodilution method without recirculation of the cold solution. To test the accuracy of the thermodilution method, the experimental setup included an aluminum tube to allow radial heat transfer. Variations of the following parameters were conducted: (i) the real flow rate, (ii) the distance between injection point of cold solution and the temperature sensor, (iii) the volume of injectate, and (iv) the temperature of injectate. By following the above variations, we have calculated different correction factors eliminating the influence of radial heat transfer on the estimation of flow rate by the thermodilution method. The results indicate that changes in both injectate temperature and volume have no influence on the estimation of flow rates. The experimental variations, which can cause greater radial heat transfer, seem to be responsible for the result of the smaller estimation of the flow rate than the real value. These variations include (i) a decreased real flow rate and (ii) increased distances between the injection point of cold fluid and the thermosensor. Such an incorrect estimation could be eliminated by using correction factors. The correction factor seems to be a function of the area of the thermodilution curve, assuming no recirculation.
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    Effects of acute treatment with dexamethasone on hemodynamic and histopathological changes in rats
    Ekerbiçer, N; Inan, S; Tarakçi, F; Barut, T; Gürpinar, T; Ozbek, M
    We assessed the time-dependent effects of intraperitoneal (i.p.) and intravenous (i.v.) application of dexamethasone (Dexa) on the mean arterial blood pressure (MAP), heart rate (HR) and total blood volume (TBV). We evaluated also the relation between the effects and immunoreactivities of transforming growth factor-beta (TGF-beta), epithelial nitric oxide synthase (eNOS), interleukin-1 beta (IL1-beta) and vascular endothelial growth factor (VEGF) in rat brain, lung and kidney tissues. Rats were anesthetized and while still breathing spontaneously, a tracheotomy and femoral vein and artery catheterizations were performed. To determine TBV using the hemodilution method, 2 ml albumin-electrolyte solutions were applied by i.v. injection. Group 1 (control group) received a 1 ml bolus injection of physiologic saline, Group 2 received 15 mg/kg and Group 3 received 75 mg/kg Dexa i.p. The hematocrit was measured at 10, 20, 60 and 120 min. For each animal, the values of MAP, HR and TBV were measured within 2 h. For immunohistochemical evaluation, anti-TGF-beta, anti-eNOS, anti-IL1-beta and anti-VEGF primary antibodies were tested using the avidin-biotin-peroxidase method. TBV was decreased in Group 1 and the increase in MAP was statistically significant. HR values increased slightly. None of the values changed significantly in Group 2. Although TBV was unchanged in Group 3, the decrease in MAP was statistically significant. HR values increased, but the increase was not statistically significant. Mild IL1-beta immunoreactivity and moderate TGF-beta, eNOS and VEGF immunoreactivities were observed in the brain, lung and kidney samples in Group 1. Increased eNOS immunoreactivity in the kidney samples were observed in Group 2. eNOS immunoreactivity was as strong in the brain and the kidney samples in Group 3. Decreased VEGF immunoreactivity was observed in the lung and kidney tissues in Group 3. Significantly decreased TGF-beta immunoreactivity was observed in all tissue samples in Group 3. The decreased MAP values in Group 3 differed from those in Groups 1 and 2. Despite increased eNOS immunoreactivity, especially in brain and kidney, the decrease in VEGF immunoreactivity in Group 3, especially lung and kidney, were consistent with a drop in blood pressure.
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    Effects of adenosine A1 receptor agonist CCPA and antagonist DPCPX on ischemia/reperfusion-induced arrhythmias in rats
    Bozdogan, Ö; Gonca, E; Ekerbiçer, N
    Aim: Adenosine has been commonly used to treat supraventricular tachycardia in clinics. However, there are only a few studies on the effects of adenosine on ischemia or reperfusion induced arrhythmia and they conflict with the results of the present study. During this study, we aimed to clarify the effect of adenosine on ischemia-reperfusion induced arrhythmia. Materials and methods: Left coronary artery was ligated for 6 min and it was released for 15 min to produce reperfusion. At adenosine agonist CCPA (2 Chloro - N6 - Cyclopentyl-adenosine), and A1 selective antagonist DPCPX (8 - Cyclopentyl - 1,3 -dipropylxanthine) in 5 mu g/kg dose alone and in combination were given intravenously before ligation, at the second minute of the ligation and just following the reperfusion. Results: Adenosine given only at the second minute of the ligation is found to decrease the total duration of arrhythmia observed in the reperfusion stage. DPCPX given in this period is found to block the antiarrhythmic effect of adenosine. Adenosine given after reperfusion and before ligation was not effective in decreasing reperfusion induced arrhythmia. Conclusion: The time dependent effect of the administration during ischemia and reperfusion was important for the effect of adenosine. The present study showed that antiarrhythmia produced by adenosine is related to the activation of A1 adenosine receptor.
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    The Effect of Atorvastatin on the Decrease of IGF-1 Level at Diabetic Rats' Kidney
    Ekerbiçer, N; Inan, VS; Çetinkaya, C; Sisman, AR; Aksu, I; Harzadin, NU