Yazar "Yilmaz, I" seçeneğine göre listele
Listeleniyor 1 - 10 / 10
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe Adhesion formation after microlaparoscopic and laparoscopic ovarian coagulation for polycystic ovary disease(Journal Amer Assoc Gynecologic Laparoscopists, 1999) Taskin, O; Sadik, S; Onoglu, A; Gokdeniz, R; Yilmaz, I; Burak, F; Wheeler, JMStudy Objective. To compare the effects of microlaparoscopy and decreased CO2 exposure on peritoneal microcirculation and potential adhesion formation after ovarian surgery with those of conventional operative laparoscopy. Design. Prospective, randomized study (Canadian Task Force classification I). Setting. Teaching hospital. Patients. Eighteen women with polycystic ovary disease. Interventions. Microlaparoscopic or laparoscopic ovarian coagulation of the ovaries. Measurements and Main Results. Approximately 10 to 12 coagulation points were applied to each ovary. Two to 3 weeks after the initial surgery second-look microlaparoscopy was performed to determine the extent of adhesions in both groups. The frequency of adhesion formation and changes in glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH) levels were studied in homogenized peritoneal tissues obtained during surgery in each group. Results. Clinical profiles were similar between groups. Mean exposure, amount, and pressure of CO2 were significantly less in the microlaparoscopy group (p <0.05). The laparoscopy group had significantly more adhesions than the microlaproscopy group (24% vs 48%, p <0.05). The GSH-Px, SOD, CAT, and GSH levels were significantly lower in the laparoscopy group (0.425 mu mol, 1.2 ng, 37.55 mu mol, and 0.9 nmol vs 0.755 mu mol, 2.1 ng, 625 mu mol, and 2.6 nmol, respectively). Conclusion. Reduced exposure to and amount of CO2 during microlaparoscopy may result in decreased adhesion formation compared with conventional laparoscopy. This effect may possibly be due to lack of or minimal adverse effects on peritoneal microcirculation and cell-protective systems, which are proposed mechanisms for adhesion formation and closely related to peritoneal injury. In addition, microlaparoscopy may be a cost-effective alternative to conventional laparoscopy.Öğe The effect of carbon dioxide pneumoperitoneum on free radicals(Springer, 2000) Sare, M; Yilmaz, I; Hamamci, D; Birincioglu, M; Özmen, M; Yesilada, ÖBackground: Carbon dioxide is usually preferred as the insufflating agent for laparoscopic surgery because it is readily available, noncombustible, and chemically stable. It is still questionable, however, if CO2 pneumoperitoneum has any effect on free radicals and lipid peroxidation. The purpose of this study was to investigate the possible effects of CO2 pneumoperitoneum on free radicals and lipid peroxidation in the erythrocytes of rats. Methods: Fifty male Sprague-Dawley rats were divided into five equal,groups: controls, a sham-operation group, and three groups of 5, 10, or 15 mmHg pneumoperitoneum with CO2. At the end of the procedure, blood was collected and the erythrocytes were separated from the plasma. The resultant supernatant fractions of erythrocytes were assayed For superoxide dismutase (SOD), catalase (CAT), and malondialdehyde (MDA). Results: SOD activities of the 5 and 10 mmHg pneumoperitoneum groups were significantly lower than those of the sham operation group. SOD activity was greater in the 15 mmHg pneumoperitoneum group than in any of the other groups, and this activity was significantly different from that seen in the 5 and 10 mmHg pneumoperitoneum groups (p < 0.05). No significant changes were observed in the CAT activities of the study,groups (p > 0.05). MDA level was increased in the 5 mmHg pneumoperitoneum group; this result was statistically different from the control and 15 mmHg pneumoperitoneum groups (p < 0.05). No significant differences were found in the CAT activities for the study groups. On the other hand, the SOD activities of the 5 and 10 mmHg pneumoperitoneum groups were significantly lower than those of the sham and the 15 mmHg pneumoperitoneum group (p < 0.05 for all comparisons). Conclusions: These results indicate that CO2 pneumoperitoneum applied with 5-10 mmHg pressure increases the formation of free oxygen radicals by inhibiting SOD activity and that the accumulation of free radicals elevates the level of MDA, a metabolite of Lipid peroxidation. The effect of CO2 pneumoperitoneum on free radicals and lipid peroxidation is pressure-dependent in rats. The mechanism underlying this pressure dependency is still under investigation.Öğe Effects of carbon dioxide pneumoperitoneum on free radical formation in lung and liver tissues(Springer, 2002) Sare, M; Hamamci, D; Yilmaz, I; Birincioglu, M; Mentes, BB; Özmen, M; Yesilada, ÖBackground: The purpose of this study was to investigate the possible effects of carbon dioxide (CO2) pneumoperitoneum on free radical formation and lipid peroxidation in the lung and liver tissues of rats. Methods: For this study, 50 male Sprague-Dawley rats were divided into five equal groups: control (group 1); sham operation (group 2): 5, 10, or 15 mmHg (group 3, 4, or 5) pneumoperitoneum with CO2 groups. At the end of the procedures, the rats were killed, and perfusion was performed via vena jugularis with cold Ringer's lactate. After the perfusion procedure, the lung and liver were harvested, and the supernatant fractions of the lungs and livers were assayed for superoxide dismutase (SOD), catalase (CAT), and malondialdehyde (MDA). Results: Both the lung and liver CAT activities were elevated consistently and significantly in the order of the study groups. as compared with the previous groups (p < 0.01 for all comparisons). The lung and liver SOD levels were elevated in groups 4 and 5, as compared with the other groups (p < 0.05). The lung MDA was significantly higher in groups 3 and 4, but not in group 5. Significant elevation in liver MDA was noted only in the 5-mmHg pneumoperitoneum group (p < 0.05). Conclusions: These results indicate that CO2 pneumoperitoneum applied with 5, 10, or 15 mmHg pressure increases the formation of free oxygen radicals, which is counterbalanced by increased SOD and CAT activities of the lung and liver tissues. This effect of CO2 pneumoperitoneum on free radicals and lipid peroxidation appears to be pressure dependent in rats. The mechanism underlying this pressure dependency is still under investigation.Öğe The effects of duration of CO2 insufflation and irrigation on peritoneal microcirculation assessed by free radical scavengers and total glutathion levels during operative laparoscopy(Journal Amer Assoc Gynecologic Laparoscopists, 1998) Taskin, O; Buhur, A; Birincioglu, M; Burak, F; Atmaca, R; Yilmaz, I; Wheeler, JMStudy Objective. To investigate the effects of peritoneal exposure to carbon dioxide (CO2) on peritoneal microcirculation and free radical scavenger (FRS) metabolism, and its role in potential adhesion formation after operative laparoscopy. Design. Randomized, controlled study (Canadian Task Force classification I). Setting. University-affiliated hospital. Patients. Twenty-eight women undergoing operative laparoscopy for adnexal masses. Intervention. For each patient, a 1 x I-cm sidewall peritoneal flap was excised at the end of laparoscopy and numbered randomly. Similar flaps obtained from 24 women immediately after entering the abdomen during laparotomy served as controls. Measurements and Main Results. Changes in glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH) levels were studied in homogenized peritoneal tissues. The duration of CO2 exposure and amount of CO2 used were correlated with levels of free radical scavengers and compared with controls. Mean CO2 exposure, amount of CO2 used, and CO2 pressure (15 mm Hg) was similar between low irrigation and irrigated laparoscopy (118.3 +/- 25 and 39.2 +/- 8.81 min and 125 +/- 20 and 44.5 +/- 6.81 min, respectively). The change in FRS levels was significantly correlated with duration and amount of CO2 exposure ( r = -0.92). Levels of GSH-Px, SOD, CAT, and GSH were significantly lower in the CO2 exposure group than in controls (0.57 els of GSH-Px, SOD, CAT; and GSH were significantly lower in the CO2 exposure group than in controls (0.57 mu mol, 1.8 ng, 48.5 mu mol, 1.5 nmol vs 0.8 mu mol, 2.6 +/- 0.4 ng, 79 mu mol, 3.6 nmol, respectively). Conclusion, Exposure to CO2 has adverse effects on peritoneal microcirculation and cell-protective systems, which are proposed mechanisms in adhesion formation. Avoiding long CO2 exposure and copiously irrigating the abdominal cavity throughout surgery may lessen these effects. The potential role of the peritoneal FRS system on postoperative adhesion formation and its relation to estrogen status mandates further studies.Öğe The effects of twisted ischaemic adnexa managed by detorsion on ovarian viability and histology: an ischaemia-reperfusion rodent model(Oxford Univ Press, 1998) Taskin, O; Birincioglu, M; Aydin, A; Buhur, A; Burak, F; Yilmaz, I; Wheeler, JMThis prospective controlled follow-up study was designed to examine the effects of adnexal torsion on long-term ovarian histology and radical scavenger (FRS) activity, and subsequent viability following the detorsion of twisted ischaemic adnexa, in a primate centre of a university clinic. Adnexal torsion/occlusion was created by twisting the adnexa three times and fixing on to the side wall or by applying vascular clips in cycling female rats at 70 days of age. Following an ischaemic period of 4 to 36 h, the twisted adnexas were surgically removed and fixed. In the second group of rats, following the above ischaemic periods, the torsion/occlusion were relieved by detwisting or removing the vascular clips. Then the animals were reperfused for a week and adnexas were extirpated. After both ischaemia and reperfusion, the removed adnexas were examined histologically and tissue concentrations of glutathione peroxidase, superoxide dismutase, catalase and glutathione were determined. Regardless of the ischaemia time, all the twisted adnexas were black-bluish in appearance. Despite the gross ischaemic-haemorrhagic features, histological sections revealed negligible changes, with intact ovarian structure similar to controls in 4-24 h groups. Though decreased compared with controls, the change in tissue concentrations of FRS was not significant in 4-24 h groups. Only the 36 h group showed prominent congestion on all sections and a significant decrease in all radical scavenger concentrations studied. While no longterm reperfusion injury was observed histologically in 4-24 h groups, the 36 h group ended with adnexal necrosis. Our findings support the importance of early diagnosis and conservative surgical management (detorsion) in adnexal torsion. Lack of histological changes and unimpaired FRS metabolism are consistent with the recent data that vascular compromise is caused by venous or lymphatic stasis in early torsion and that adnexal integrity is not correlated with gross ischaemic appearance, thus providing evidence of adnexal resistance against ischaemia.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 Endometrial Na+, K+-ATPase pump function and vasopressin levels during hysteroscopic surgery in patients pretreated with GnRH agonist(Journal Amer Assoc Gynecologic Laparoscopists, 1998) Taskin, O; Buhur, A; Birincioglu, M; Burak, F; Atmaca, R; Yilmaz, I; Wheeler, JMStudy Objective. To investigate the effects of gonadotropin-releasing hormone (GnRH) analog pretreatment on endometrial Na+, K+-adenosine triphosphatase (ATPase) pump function and peripheral blood vasopressin levels, and their role in fluid absorption and mechanisms of hyponatremia in patients undergoing hysteroscopic endometrial ablation. Design. Prospective, randomized, placebo-controlled study (Canadian Task Force classification I). Setting. University-affiliated hospital. Patients. Seventeen women with dysfunctional uterine bleeding. Intervention, Nine women received a GnRH analog and eight received saline approximately 6 to 8 weeks before hysteroscopic ablation by electrosurgery. Measurements and Main Results. Both before randomization and immediately before surgery, endometrial biopsy samples were obtained and numbered consecutively without patient identification. Operative hysteroscopy was performed with glycine 1.5% mixed with 2% alcohol. The amount of irrigant and irrigant deficit; blood levels of albumin and ethanol; hematocrit and hemoglobin; changes in sodium levels; and central venous pressure were compared. The Na+, K+-ATPase pump activity was significantly increased in the GnRH analog group compared with the saline group and correlated with decreased estradiol levels (0.4 +/- 0.08 vs 0.26 +/- 0.06 mu mol/min/ml). Vasopressin levels were significantly lower in the GnRH group (3.2 +/- 0.9 vs 7.6 +/- 1.7 mu mol/L). Mean volume of irrigant used and operating time were similar in both groups. Volume deficit, decrease in protein, and hematocrit were less in GnRH than in the saline group. Blood ethanol levels, decrease in sodium, and irrigant deficit were significantly lower in GnRH group. Conclusion. Pretreatment with GnRH analogs may prevent the adverse effects of estradiol on endometrial Na+, K+-ATPase and creates a protective mechanism against iatrogenic hyponatremia, which is more critical in women than men in case of absorption of irrigating fluid. Moreover, created hypoestrogenism may enhance Na+, K+-ATPase activity in brain as well as endometrium, thus decreasing women's susceptibility to hyponatremic complications and brain damage. Suppressed vasopressin levels may be protective against fluid absorption in GnRH analog-treated patients.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.
