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Öğe ANTIMONY INDUCED GLUTATHIONE EFFLUX FROM HUMAN ERYTHROCTES(Parlar Scientific Publications (P S P), 2016) Sahilli, Yeliz Cakir; Akgun, Mehmet Hanifi; Yildiz, DenizAntimony is a trace element which has wide variety of industrial application. Antimony has recently been considered as an environmental pollutant. Among the inorganic forms, SbIII is the more toxic form. SbIII is ten times more toxic compared to the SbV. Consuming plants that are grown in antimony contaminated soil is one of the way by which humans are exposed to antimony. AsIII and SbIII forms strong bonds with free-SH groups. When SbIII or SbV interacts with proteins that contain free-SH groups, protein inactivation usually results in. Antimony may also result in free radical generation and induction of oxidative stress. Even though antimony has some applications in health as a drug, its biological effects have not been investigated in detail. In the present study we investigated the effects of SbIII on glutathione efflux in human erythrocytes. The effects of N-acetyl-L-cysteine on antimony induced glutathione oxidation and glutathione efflux were also investigated. Extracellular glutathione concentration significantly increased and reached to 0.033 +/- 0.0034 micromole/ml erythrocyte with 1 mM of potassium antimony tartrate in four hours. The control value of extracellular glutathione was 0.020 +/- 0.0035 micromole/ml erythrocyte. Our results show that SbIII treatment of erythrocyte results in glutathione efflux.Öğe Arsenate V induced glutathione efflux from human erythrocytes(Elsevier Gmbh, 2012) Yildiz, Deniz; Cakir, YelizObjective: The objective of the present study was to investigate if arsenate V exposure results in glutathione efflux from human erythrocytes. Procedure: The changes in intracellular and extracellular nonprotein sulfhydryl and glutathione levels were determined in arsenate (V) exposed erythrocytes. Presence of any cellular membrane damage was assessed by lactate dehydrogenase activity measurement in the supernatant. Results: When erythrocytes were exposed to 10 mM of arsenate (V) for 4h, the intracellular NPSH level decreased to 0.28 +/- 0025 mu mol/ml erythrocyte. In contrast, extracellular nonprotein thiol level was increased to 0.180 +/- 0.010 mu mol/ml erythrocyte in 4h. Extracellular glutathione levels reached to 0.028 +/- 0.001, 0.052 +/- 0.002, and 0.054 +/- 0.004 mu mol/ml erythrocyte with 1, 5, and 10 mM of arsenate (V), respectively. Utilization of MK571 a multi drug resistance-associated protein 1 inhibitor decreased the rate of glutathione efflux from erythrocytes suggesting a role for this membrane transporter in the process. Conclusion: The results of the present study indicate that erythrocytes efflux glutathione when exposed to arsenate (V). (C) 2011 Elsevier GmbH. All rights reserved.Öğe Effects of acetylsalicylic acid on rats: An in vivo experimental study in azaserine-rat model(Wolters Kluwer Medknow Publications, 2019) Yildiz, Hasan; Kalipci, Erkan; Oztas, Haydar; Yildiz, DenizAim: The effect of acetylsalicylic acid (ASA) on thiol levels was studied in a rat model of azaserine carcinogenesis. Materials and Methods: ASA and azaserine were applied to the animals to research changes in cellular sulfhydryl (-SH) content and variations in free and protein-bound molecules containing the -SH group. Such effects in rats injected with azaserine were investigated at low (200 ppm) and high (400 ppm) concentrations of ASA over a relatively short (6 months) and a relatively long (12 months) period. Results: Changes in the hepatic, pancreatic, and renal -SH contents were also determined. Conclusion: Compared to the other tissues studied, the liver contained the highest levels of both free and protein-bound -SH.Öğe Efflux of Glutathione and Glutathione Complexes from Human Erythrocytes in Response to Inorganic Arsenic Exposure(Humana Press Inc, 2012) Yildiz, Deniz; Cakir, YelizThe objective of the present study was to investigate if arsenic exposure results in glutathione efflux from human erythrocytes. Arsenite significantly depleted intracellular nonprotein thiol level in a time- and concentration-dependent manner. The intracellular nonprotein thiol level was decreased to 0.767 +/- 0.0017 mu mol/ml erythrocyte following exposure to 10 mM of arsenite for 4 h. Extracellular nonprotein thiol level was increased concomitantly with the intracellular decrease and reached to 0.481 +/- 0.0005 mu mol/ml erythrocyte in 4 h. In parallel with the change in extracellular nonprotein thiol levels, significant increases in extracellular glutathione levels were detected. Extracellular glutathione levels reached to 0.122 +/- 0.0013, 0.226 +/- 0.003, and 0.274 +/- 0.004 mu mol/ml erythrocyte with 1, 5, and 10 mM of arsenite, respectively. Dimercaptosuccinic acid treatment of supernatants significantly increased the glutathione levels measured in the extracellular media. Utilization of MK571 and verapamil, multidrug resistance-associated protein 1 and Pgp inhibitors, decreased the rate of glutathione efflux from erythrocytes suggesting a role for these membrane transporters in the process. The results of the present study indicate that human erythrocytes efflux glutathione in reduced free form and in conjugated form or forms that can be recovered with dimercaptosuccinic acid when exposed to arsenite.Öğe Efflux of glutathione and glutathione complexes from human erythrocytes in response to vanadate(Academic Press Inc Elsevier Science, 2013) Cakir, Yeliz; Yildiz, DenizThe main objective of the present study was to investigate if vanadate is extruded from the cells in a glutathione dependent manner resulting in the appearance of extracellular glutathione and complexes of glutathione with vanadium. Vanadate significantly depleted intracellular non-protein sulfhydryl (NPSH) levels in a time- and concentration-dependent manner. The intracellular NPSH level was decreased to 0.0 +/- 0.0 mu mol/ml erythrocyte when exposed to 10 mM of vanadate for 4 h. Extracellular NPSH level was increased concomitantly with the intracellular decrease and reached to 0.1410 +/- 0.005 mu mol/ml erythrocyte in 4 h. Intracellular decrease and extracellular increase in NPSH levels were significantly inhibited in the presence of DIDS, a chloride-bicarbonate exchanger which also mediates phosphate and arsenate transport in erythrocytes. In parallel with the increase in extracellular NPSH levels, significant increases in extracellular glutathione levels were detected following exposure to vanadate. Extracellular glutathione levels reached to 0.0150 +/- 0.0.001, 0.0330 +/- 0.001, and 0.0576 +/- 0.002 mu mol/ml erythrocyte with 1, 5, and 10 mM of vanadate respectively. Dimercaptosuccinic acid treatment of supematants significantly increased the glutathione levels measured in the extracellular media. Utilization of MK571 an MRP inhibitor decreased the rate of glutathione efflux from erythrocytes suggesting a role for this membrane transporter in the process. A known methylation inhibitor periodate oxidized adenosine decreased the rate of glutathione efflux from erythrocytes. This observed decrease in extracellular GSH levels suggests that GSH release partly requires a proper cellular methylation process and that part of GSH detected in the extracellular media may arise from GSH-vandium complexes. The results of the present study indicate that human erythrocyte efflux glutathione in reduced free form and in conjugated form/s that can be recovered with dimercaptosuccinic acid when exposed to vanadate. (C) 2012 Elsevier Inc. All rights reserved.Öğe Homocysteine Influx and Efflux: Participation of Erythrocytes in Homocysteine Homeostasis of the Plasma(Gazi Univ, 2010) Yildiz, Deniz; Civi, Zuleyha; Cakir, YelizOne of the main objective of the present study was to determine if erythrocytes play a role in regulation of plasma homocysteine concentration. Another objective was to investigate if erythrocytes convert homocystine into homocysteine. In the present study, we exposed erytrocytes to different concentrations of homocysteine and then measured the nonprotein sulfhydryl (NPSH) concentrations. Erythrocytes treated in the same manner were later utilized for the homocysteine efflux studies. The effect of temperature on the influx and the efflux processes were also evaluated. We also determined the rate of homocysteine influx in the presence of different amino acids. The homocysteine influx studies demonstrated that erythrocytes can respond to increases in homocysteine concentration in the extracellular media and influx homocysteine in a concentration-dependent manner. NPSH concentrations in erythrocytes treated with 1 mM homocysteine reached to 1.47 +/- 0.01 mu mol/ml erythrocyte in 1 h whereas this concentration reached to 2.01 +/- 0.1 mu mol/ml erythrocyte in 3 mM homocysteine treated erytrocytes. The homocysteine efflux is also determined to be time-and concentration -dependent. Extracellular concentration of NPSH in 1 mM homocysteine pre-treated erythrocytes reached to 0.266 +/- 0.02 mu mol/ml erythrocyte in 1 h whereas this concentration reached to 0.64 +/- 0.01 mu mol/ml erythrocyte with 3 mM homocysteine pre-treated erythrocytes. Our results also indicate that erythrocytes convert extracellulary applied homocystine into homocysteine. Depending on our results, it could be concluded that eryhtrocytes may play a significant role in the regulation of plasma homocysteine homeostasis.Öğe Homocysteine influx and efflux: Participation of erythrocytes in homocysteine homeostasis of the plasma(Gazi University Eti Mahallesi, 2010) Yildiz, Deniz; Civi, Zuleyha; Cakir, YelizOne of the main objective of the present study was to determine if erythrocytes play a role in regulation of plasma homocysteine concentration. Another objective was to investigate if erythrocytes convert homocystine into homocysteine. In the present study, we exposed erytrocytes to different concentrations of homocysteine and then measured the nonprotein sulfhydryl (NPSH) concentrations. Erythrocytes treated in the same manner were later utilized for the homocysteine efflux studies. The effect of temperature on the influx and the efflux processes were also evaluated. We also determined the rate of homocysteine influx in the presence of different amino acids. The homocysteine influx studies demonstrated that erythrocytes can respond to increases in homocysteine concentration in the extracellular media and influx homocysteine in a concentration-dependent manner. NPSH concentrations in erythrocytes treated with 1 mM homocysteine reached to 1.47 ± 0.01 imol/ml erythrocyte in 1 h whereas this concentration reached to 2.01 ± 0.1 imol/ml erythrocyte in 3 mM homocysteine treated erytrocytes. The homocysteine efflux is also determined to be time-and concentration -dependent. Extracellular concentration of NPSH in 1 mM homocysteine pre-treated erythrocytes reached to 0.266 ± 0.02 imol/ml erythrocyte in 1 h whereas this concentration reached to 0.64 ± 0.01 imol/ml erythrocyte with 3 mM homocysteine pre-treated erythrocytes. Our results also indicate that erythrocytes convert extracellulary applied homocystine into homocysteine. Depending on our results, it could be concluded that erythrocytes may play a significant role in the regulation of plasma homocysteine homeostasis.Öğe Hyperosmolarity induced cystine transport and cystine-cysteine cycle between erythrocytes and the plasma(Pharmaceutical Soc Japan, 2008) Yildiz, Deniz; Cakir, YelizThe objective of the present study was to determine if a cystine-cysteine cycle operates between the erythrocytes and the plasma. In the present study we incubated the erythrocytes in krebs ringer phosphate buffer with different osmolarity containing different amounts of cystine. Our results show that erythrocytes do not uptake cystine from the environment when the osmolarity of the buffer is 310mOsmol/l.Erythrocytes also do not operate a cystine-cysteine cycle in this isoosmolar buffer. However, when exposed to hyperosmolar buffer in the ranges that occur in the kidney medulla which is in between 1200-1400 mOsmol/l erythrocytes start to uptake cystine from the environment and induce a cystine-cysteine cycle. The cystine uptake and cystine-cysteine cycle were characterized by measurement of changes in the free -SH concentrations in erythrocytes and in the buffer. Following incubation of erythrocytes in 1 mM cystine containing 1250 and 1300 mOsmol/l buffer, the free -SH concentrations in the buffer reached to 0. 102 +/- 0.002 and 0.241 +/- 0.013 mu mol/ml erythrocyte respectively. Our results demonstrate that erythrocytes display a cystine-cysteine cycle in hyperosmolar environment which is prevailed mainly in the kidney medulla. Our results also display that this process is biologically active and energy dependent. The observed cystine-cysteine cycle is inhibited when the erythrocytes are incubated at lower temperatures and in the absence of glucose. Our results suggest that erythrocytes uptake cystine, intracellulary reduce it to cysteine and release it back to the environment when exposed to hyperosmolar conditions. Erythrocytes may have a role in the regulation of plasma cystine and cysteine concentrations and may contribute to the regulation of plasma redox status.Öğe Inhibitory effects of Aspirin on Azaserine initiated pancreatic carcinogenesis in rat(Indian Veterinary Journal, 2008) Yildiz, Hasan; Koc, Ahmet; Oztas, Haydar; Yildiz, DenizIn vitro experiments and limited animal studies suggest that aspirin, nonsteroidal anti-inflammatory, drug may inhibit pancreatic carcinogenesis. So far researchers have evaluated the biochemical and metabolic properties of aspirin but there has not been any experimental study performed on the anticarcinogenesis effect of aspirin on the well-known azaserine-rat model for pancreatic carcinogenesis. This study was designed to evaluate the potential anticarcinogenetic effect of aspirin.Öğe Methyl parathion-induced changes in free and protein-bound SH levels in rat tissues(Taylor & Francis Ltd, 2006) Yildiz, Deniz; Dalkilic, Semih; Yildiz, Hasan; Oztas, HaydarThe main objective of this study was to investigate the changes in free and protein-bound SH contents in methyl parathion-exposed rat tissues. The free and protein-bound SH levels are usually affected and depleted by oxidative stress-inducing agents. Results would indicate if methyl parathion toxicity partly results from depletion of sulfhydryl content of tissues. Six-week-old male Wistar albino rats were used in this study. Following exposure to methyl parathion for 3 months, the liver, the brain, and the kidney tissues were removed from the rats. The free and protein-bound SH contents were determined in these tissues. In addition, plasma lactate dehydrogenase levels were determined. Our results showed that methyl parathion exposure significantly lowers the free and protein-bound SH levels in rat tissues. However, lactate dehydrogenase activity in the blood plasma did not display any differences compared to the control group. The free SH concentrations in the control rat liver, brain, and kidney tissues were 3.78 +/- 0.1 mu mol/100 mg tissue, 1.56 +/- 0.08 mu mol/100 mg tissue, and 2.16 +/- 0.08 mu mol/100 mg tissue, respectively, whereas the free SH concentrations in rats exposed to methyl parathion were determined as 0.536 +/- 0.1 mu mol/100 mg tissue in the liver, 1.06 +/- 0.1 mu mol/100 mg tissue in the brain, and 0.108 +/- 0.03 mu mol/100 mg tissue in the kidney. The protein-bound SH concentrations in the liver and in the kidney in rats exposed to methyl parathion displayed a significant decrease also. However, the protein-bound SH level in the brain did not change significantly. These results indicate that methyl parathion exposure partially depletes the free and protein-bound SH levels. Thus, it was concluded that methyl parathion toxicity may partly result from oxidative stress.Öğe Nicotine metabolism and its biologic effects(2003) Yildiz, DenizNicotine is a naturally occuring alkaloid found in many plants. The principal sources of nicotine exposure is through the use of tobacco, nicotine containing gum and nicotine replacement therapies. Nicotine is an amine composed of pyridine and pyrrolidine rings. It has been shown that nicotine crosses biological membranes and the blood brain barrier easily. The absorbed nicotine is extensively metabolised in the liver to form a wide variety of metabolites including nicotine N'-oxide and cotinine N'-oxide. These are the products of mixed function oxidase system. Nicotine is also converted to some biologically important compounds during harvesting. Among these are the nitrosamines specific to tobacco. Nicotine has been shown to affect a wide variety of biological functions ranging from gene expression, regulation of hormone secretion and enzyme activities.Öğe Ultrastructural changes in pancreatic acinar cells of fatty acids fed rat(Indian Veterinary Journal, 2008) Oztas, Hayder; Koc, Ahmet; Yildiz, DenizResearchers have shown that oleic acid increases the proliferation of normal and neoplastic mammary cells in vitro, whereas saturated fatty acids (stearic acid and palmitic acid) do not (Kidwell et al., 1982). Administration of diets with an altered fat composition appears to affect the ultra structure of rat pancreatic acinar cells (Gauvreau et al., 1992). The objective of the present study was to investigate the ultra structural changes in pancreatic acinar cells in azaserine initiated and fatty acid fed rats.
