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Öğe Effect of caffeic acid phenethyl ester on heart rate and blood pressure in anaesthetized rats(Federation Amer Soc Exp Biol, 2005) Iraz, M; Fadillioglu, E; Tasdemir, S; Ates, B[Abstract Not Available]Öğe Effects of various sodium selenite concentrations on some biochemical and hematological parameters of rainbow trout (Oncorhynchus mykiss)(Parlar Scientific Publications (P S P), 2005) Orun, I; Ates, B; Selamoglu, Z; Yazlak, H; Ozturk, E; Yilmaz, IIn this study the activity of selenium-dependent glutathione peroxidase (Se-GSH-Px) and the levels of superoxide dismutase (SOD) and malondialdehyde (MA) of rainbow trouts exposed to various concentrations of selenium were determined. Furthermore, the hematological parameters from blood tissue were studied. Although, Se-GSH-Px activity generally increased in all groups for brain, heart and spleen tissues with respect to the control group, the only statistically significant difference (p<0.05) was found in liver tissues of trouts exposed to 4 and 6 ppm sodium selenite (SS). The SOD levels of spleen, heart, liver and brain tissues of 2 and 4 ppm SS-treated fish were also significantly higher than those of control group animals (p<0.05). The MDA values, an indicator for oxidative damage in the cell, were lower in all tissues with regard to control. Furthermore, the erythrocyte number, hemoglobin amount and hematocrit value of SS-treated rainbow trouts were significantly lower than that of control animals (p<0.05). The results show that SS has an important effect on the antioxidative defense at 2 and 4 ppm levels, whereas a 6 ppm dosage appears to be lethal for rainbow trouts.Öğe Membrane permeabilization of gram-negative bacteria with a potassium phosphate/hexane aqueous phase system for the release of L-asparaginase: an enzyme used in cancer therapy(Elsevier Sci Ltd, 2005) Geckil, H; Ates, B; Gencer, S; Uckun, M; Yilmaz, IA fast, efficient and reproducible recovery procedure for periplasmic L-asparaginase from two distinctly related gram-negative bacteria, Enterobacter aerogenes and Pseudomonas aeruginosa, is presented. As the method uses inexpensive organic solvent hexane and an aqueous salt solution, it is also highly cost-effective in comparison with the currently available techniques used for the release of this enzyme. As hexane is a highly water immiscible organic solvent, it can be removed easily from the top of the aqueous phase by a simple evaporation. Also, various organic solvents and other membrane partitioning compounds were compared for their efficiency on L-asparaginase/protein release. The degree to which the enzyme was released was different for two bacteria, suggesting that they possess different permeability characteristics. The most efficient enzyme release from both bacteria was determined to be in 50 mM potassium phosphate with 1% hexane. Enzyme recoveries up to three-fold with respect to sonication have been achieved with this system. (C) 2004 Elsevier Ltd. All rights reserved.Öğe Protective role of caffeic acid phenethyl ester in the liver of rats exposed to cold stress(Wiley-Blackwell, 2006) Ates, B; Dogru, MI; Gul, M; Erdogan, A; Dogru, AK; Yilmaz, I; Yurekli, MCold exposure can induce a form of environmental stress. Cold stress (CS) alters homeostasis, results in the creation of reactive oxygen species and leads to alterations in the antioxidant defense system. The caffeic acid phenethyl ester (CAPE), an active component of propolis, has an antioxidant capacity. We investigated the effect of CS on oxidative stress and antioxidant defense system and the possible protective effect of CAPE in rat liver tissue. Twenty-four female Wistar Albino rats were divided into four groups: Control, CAPE-treated, CS, and CAPE-treated CS (CS + CAPE) group. Catalase (CAT), glutathione peroxidase (GSH-Px), superoxide dismutase (SOD) activities and total glutathione (GSH) and malondialdehyde (MDA) levels were measured. In addition, histological changes in liver tissue were examined by light microscopy. SOD, CAT and GSH-Px activities and total GSH level were significantly declined in the CS group. In the CS + CAPE group, the activities of these three enzymes and GSH level significantly raised with regard to the CS group. MDA levels increased in the CS group and decreased in the CS + CAPE group. The tissues of the CS group showed some histopathological changes such as necrosis, hepatocyte degeneration, sinusoidal dilatation, hemorrhage and vascular congestion and dilatation. In the CS + CAPE group, the histopathological evidence of hepatic damage was markedly reduced. Histological parameters were consistent with biochemical parameters. In this study, CS increased oxidative stress in liver tissue. CAPE regulated antioxidant enzymes, inhibited lipid peroxidation and reduced hepatic damage.Öğe Protective role of melatonin given either before ischemia or prior to reperfusion on intestinal ischemia-reperfusion damage(Wiley, 2004) Ates, B; Yilmaz, I; Geckil, H; Iraz, M; Birincioglu, M; Fiskin, KTissue injury resulting from ischemia-reperfusion is of fundamental importance. Experimental evidence suggests that the generation of reactive oxygen species is significantly responsible for this type of injury. In the present study, besides investigating the protective role of melatonin on tissue damage caused by intestinal ischemia-reperfusion, the protective activity of this compound was also analyzed in both pre- and post ischemia melatonin-treated rats. The activities of the main antioxidative enzymes, catalase, superoxide dismutase and glutathione peroxidase in the intestine showed significant (P < 0.05) increases in melatonin-treated animals that were subjected to ischemia/reperfusion compared with those subjected only to ischemia/reperfusion. Also, results clearly indicate that the level of malondialdeyhde, an index of lipid peroxidation, decreased significantly (P < 0.05) when rats subjected to intestinal/reperfusion were given melatonin either before ischemia or before reperfusion.Öğe Ultrastructural clues for the protective effect of melatonin against oxidative damage in cerulein-induced pancreatitis(Wiley, 2006) Esrefoglu, M; Gül, M; Ates, B; Selimoglu, MAThe role of oxidative stress has been evaluated in experimental models of acute pancreatitis (AP). The aim of this study is to investigate the effect of melatonin on the ultrastructural changes in cerulein-induced AP in rats. Acute pancreatitis was induced by two i.p. injections of cerulein at 2-hr intervals (50 mu g/kg BW). One group received additionally melatonin (20 mg/kg BW) i.p. before each injection of cerulein. The rats were sacrificed 12 hr after the last injection. Pancreatic oxidative stress markers were evaluated by changes in the amount of lipid peroxides and changes in the antioxidant enzyme levels, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and total glutathione (GSH) levels. Ultrastructural examination was performed using a transmission electron microscope. Formation of numerous, large autophagosomes, mitochondrial damage, dilatation of rough endoplasmic reticulum (RER) and Golgi apparatus, margination and clumping of nuclear chromatin were the major ultrastructural alterations observed in the AP group. Melatonin administration prevented mitochondrial and nuclear changes and dilatation of RER and Golgi apparatus. Rare, small autophagosomes were present within the cytoplasm of some of the acinar cells. Pancreatic damage was accompanied by a significant increase in tissue MDA levels (P < 0.05) and a significant decrease in CAT, SOD, GPx activities and GSH levels (P < 0.005). Melatonin administration significantly reduced MDA levels but increased CAT, SOD, GPx activities and GSH levels (P < 0.005). Melatonin also reduced serum amylase and lipase activities, which were significantly elevated in AP (P < 0.05 and P < 0.005 respectively). These results suggest that oxidative injury is important in the pathogenesis of AP. Melatonin is potentially capable of limiting pancreatic damage produced during AP by protecting the fine structure of acinar cells and tissue antioxidant enzyme activities.Öğe Vitreoscilla hemoglobin renders Enterobacter aerogenes highly susceptible to heavy metals(Springer, 2004) Geckil, H; Arman, A; Gencer, S; Ates, B; Yilmaz, HRWhen expressed in heterologous microorganisms Vitreoscilla hemoglobin (VHb) acts as oxygen storage and causes a higher oxygen uptake. In this study, the effect of this protein on growth, sensitivity and antioxidant properties of Enterobacter aerogenes exposed to metal stress was investigated. The strain expressing VHb was more sensitive to mercury and cadmium as the minimal inhibitory concentration (MIC) for these metals was up to 2-fold lower in this strain than the host and the recombinant strain carrying a comparable plasmid. At lower concentrations than MIC, the metals partially limited growth and caused an inhibition proportional to metal concentration applied. The growth pattern of VHb expressing strain was also distinctly different from other two non-hemoglobin strains. The hemoglobin containing strain showed substantially higher superoxide dismuates (SOD) activity than the non-hemoglobin strains, while catalase levels were similar in all strains. All strains exposed to copper, however, showed similar MIC values, growth patterns, and SOD and catalase levels.
