Browsing by Author "Karaayvaz, M"

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Aspirin Enhances Myocardial Inducible Nitric Oxide Synthase Activity in Guinea Pigs
(Elsevier Science Bv, 1999) Durak, I; Karaayvaz, M; Öztürk, HS
Aspirin Impairs Antioxidant System and Causes Peroxidation in Human Erythrocytes and Guinea Pig Myocardial Tissue
(Sage Publications Ltd, 2001) Durak, I; Karaayvaz, M; Çimen, MYB; Avci, A; Çimen, ÖB; Buyukkoçak, S; Kaçmaz, M
This study aims to investigate possible effects of aspirin treatment on cellular oxidant/antioxidant system. In the first part of the study, 15 guinea pigs were given aspirin at three different doses (2200, 440 and 10 mg/kg/day) for 30 days and five were fed on the same diet without aspirin. After a month, animals were killed and their hearts were removed for use in analyses. In the other part, after fasting blood samples were obtained from 11 volunteer subjects, they were given aspirin (approximately 10 mg/kg/day) for 30 days and second blood samples were obtained after 1 month. Five volunteer subjects also participated as placebo control. Oxidant/antioxidant parameters, namely superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase (CAT), malondialdehyde (MDA), nonenzymatic superoxide scavenger activity (NSSA), susceptibility to oxidation (SO) and antioxidant potential (AOP) values, were assayed in the samples. Antioxidant system was found to be impaired in the heart tissue from guinea pigs and in the erythrocytes from volunteer subjects. AOP and NSSA values were lower and MDA higher after aspirin treatment in both heart tissues and erythrocytes. In guinea pig heart tissue, SO was lower, but GSH-Px and CAT were unchanged after aspirin treatment. In human erythrocytes, SO was unchanged, but GSH-Px and CAT activities were increased after aspirin treatment. Changes in guinea pig heart tissues from animals treated with higher aspirin doses were more drastic relative to those of human erythrocytes, but no meaningful differences were observed between analysis parameters of control and lower-dose (10 mg/kg/day) aspirin-treated animals. Our results suggest that high-dose aspirin exerts significant toxicity to guinea pig myocardium and normal dose aspirin may cause peroxidation in the human erythrocytes due to its oxidant potential. We suppose that antioxidant supplementation may be beneficial for the people using aspirin for longer periods in order to prevent peroxidation damages.
Cisplatin Induces Acute Renal Failure by Impairing Antioxidant System in Guinea Pigs
(Taylor & Francis Ltd, 2002) Durak, I; Özbek, H; Karaayvaz, M; Öztürk, HS
This study aims to investigate the role of oxidants in cisplatin-induced nephrotoxicity. Cisplatin was administered intraperitoneally (i.p.) in a single dose (5mg/kg) and guinea pigs were killed either after 24h or 7 days. The same experiment was performed using animals treated with vitamins C and E combination and a natural antioxidant extract (SARMEX((R))). The kidneys were then removed to be used in the analyses. Blood samples were also obtained from the animals to be used in routine biochemical assays. Twenty-four hours after treatment there was a significant decrease in the renal activities of total superoxide scavenger activity (TSSA), superoxide dismutase (SOD) and catalase (CAT) accompanied by a rise in malondialdehyde (MDA) levels. After 7 days, the fall in kidney enzymatic activities was far greater, while the increase in blood urea (BUN) and creatinine (CRE) was marked. Treatment with antioxidants causes significant increases in renal TSSA (7 day), non-enzymatic superoxide scavenger activity (NSSA) (24h and 7 day) and SOD (7 day) activities, does not change glutathione peroxidase (GSH-Px) activity and decreases renal MDA (24h and 7 day), blood BUN (7 day) and CRE (7 day) levels. Our results suggest that cisplatin treatment impairs both enzymatic and non-enzymatic antioxidant systems and causes peroxidation in the renal tissue, which leads to kidney failure. Antioxidant supplementation strengthens the renal antioxidant system, eliminates oxidation reactions, and prevents cisplatin-induced kidney failure.
The Effect of Lymphatic Blockage on the Amount of Endotoxin in Portal Circulation, Nitric Oxide Synthesis, and the Liver in Dogs With Peritonitis
(Springer verlag, 1999) Güler, O; Ugras, S; Aydin, M; Dilek, FH; Dilek, ON; Karaayvaz, M
This study was performed to investigate the effect of lymphatic blockage on the amount of endotoxin in portal venous blood, nitric oxide synthesis, the release of aspartate aminotransferase (AST) from the liver, hepatic damage, and survival in an experimental model of dogs with peritonitis, The dogs were divided into a control group (group 1), an unligated thoracic duct peritonitis group (group 2), and a ligated thoracic duct peritonitis group (group 3), Peritoneal fluid and blood from the portal vein and femoral artery were taken for peritoneal culture, endotoxin, and AST assay, respectively, and liver biopsies were performed to assess for hepatic damage and for nitric oxide assay, There was a higher bacteria count in the peritoneal fluid from group 3 than in that from group 2 (P < 0.0001), Bacteria grew in all of the blood cultures from the group 2 animals, but growth was seen only in blood cultures from four of the group 3 animals. The levels of endotoxin, nitrite, and AST levels in group 3 were significantly increased in comparison with those in group 2 (P < 0.0001), Extensive hepatocellular necrosis,vith hemorrhage was observed in the livers of the group 3 animals, and all of them died,within 48 h, The results of this study suggest that the blockage of lymph flow has a negative effect on liver and survival in dogs with peritonitis, and that hepatic damage is directly related to the amount of endotoxin to which the liver is exposed,
Prevention of Adriamycin-Induced Skin Necrosis With Various Free Radical Scavengers
(Academic Press inc, 1998) Bekerecioglu, M; Kutluhan, A; Demirtas, I; Karaayvaz, M
Infiltration of antitumor agents into subcutaneous tissues may either result in a local area of self-resolving inflammation or progress to full-thickness loss of skin and underlying vital structures. Inadvertent extravasation of adriamycin can result in severe tissue necrosis. The mechanism of this tissue damage is believed to be release of oxygen free radicals into the tissue. After adriamycin extravasation, the treatment groups were made up according to drugs used, EGb 761, pentoxifylline, alpha-tocopherol acetate, and alpha-tocopherol succinate in rats. To prevent the necrosis and to decrease the tissue malondialdehyde levels, the most effective agent was found to be EGb 761, and pentoxifylline was also effective (P < 0.001). No difference was found between topical lanoline and saline (P > 0.05). The maximum ulcer diameter was obtained in 2 weeks. The maximum tissue malondialdehyde levels were obtained in 24 h, and in comparison to the control group the treatment groups showed lower levels. Our aim is to show the role of free radicals in the formation of skin necrosis as a cause of adriamycin extravasation and to prevent or decrease the skin necrosis using various free radical scavengers. (C) 1998 Academic Press.
Primary Composite Tumour With Bipartite Differentiation of the Esophagus
(Acta Medical Belgica, 2000) Ugras, S; Akpolat, N; Er, M; Yalçynkaya, I; Karaayvaz, M
Primary small cell carcinoma of the esophagus is a rare tumour. A primary composite tumour of the esophagus is even rarer and only four cases had been reported in the literature up to August 1998. The definitive histogenesis of this tumour remains controversial in spite of the,additional information provided by electron microscopy and immunohistochemistry. In the presented:case, histologically, the tumour tissue was composed of two malignant components: approximately 50 % of a moderately differentiated squamous cell carcinoma, and approximately 50 % of a small cell carcinoma. A lot of morphological transition zones were observed between the squamous cell carcinoma components and the small cell carcinoma components in some areas in the squamous cell carcinoma component. Histochemically and immunohistochemically, the small cell carcinoma cells demonstrated argyrophil granules, and Cytokeratin and Chromogranin A reactivity, but the squamous cell carcinoma cells demonstrated only Cytokeratin reactivity. Negative reactivity for argentaffin granules, neuron-specific enolase and S-100 were observed in both the small cell carcinoma and the,squamous cell carcinoma components. Histological, histochemical:and immunohistochemical findings suggest that a primary composite tumour of the esophagus may be derived from a totipotent primitive cell in the basal region of the squamous mucosa of the esophagus. The patient received chemotherapy preoperatively but died one month after the initial diagnosis.
Primary Leiomyosarcoma of the Breast
(Springer verlag, 1997) Ugras, S; Dilek, ON; Karaayvaz, M; Dilek, H; Peker, O; Barut, I
Sarcomas of the breast are rare, accounting for about 1% of all malignant breast tumors. Leiomyosarcoma of the breast was an almost unknown tumor until some 20 years ago, and the few previously published cases lacked detailed information. Only 11 well-documented cases of leiomyosarcoma of the breast had been reported in the literature up to February 1992. The clinical features, diagnosis, therapy, and prognosis are discussed here in the light of the previously published literature.
Subdiaphragmatic Location of Costal Chondrosarcoma
(Munksgaard int Publ Ltd, 2000) Ünal, Ö; Arslan, H; Karaayvaz, M; Akpolat, N
Use of an Autologous Vein Graft and Stent in the Repair of Common Bile Defects: an Experimental Study
(Springer verlag, 1998) Karaayvaz, M; Ugras, S; Guler, O; Aydin, M; Alkan, I; Yigit, MF
We investigated the effectiveness of using an autologous vein graft and stent in the repair of large defects of the common bile duct (CBD) in a canine model. A 3-cm segment of the vena cephalica antibrachii and a 2-cm segment of the CBD were removed from eight healthy mongrel dogs with normal blood biochemistry levels. A stent was passed through the vein segment, and one end was introduced into the proximal end of the CBD while the other end was introduced into the distal end. The venous graft was then sutured to the CBD. A liver biopsy was taken for histopathological examination during laparotomy and relaparotomy. Blood samples were obtained on postoperative days 7, 14, and 20 for biochemical examination. The defect was effectively repaired by the autologous vein graft and stent in 7 dogs, after the exclusion of 1 dog that died of hemorrhage 3 days after the operation. No change in blood biochemistry was observed postoperatively, and no histopathological change in the liver was found in the preoperative or postoperative periods. These findings indicate that the use of an autologous vein graft and stent to repair CBD injuries may be a feasible and alternative method of treatment.