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Featured researches published by Iskender Sayek.


World Journal of Surgery | 2001

Diagnosis and Treatment of Uncomplicated Hydatid Cyst of the Liver

Iskender Sayek; Demiral Onat

Hydatid disease of the liver is still endemic in certain parts of the world. The diagnosis of noncomplicated hydatid cyst of the liver depends on clinical suspicion. Ultrasonography and computed tomography, the most important diagnostic tools, are helpful for determining the complications and planning treatment. The modern treatment of hydatid cyst of the liver varies from surgical intervention to percutaneous drainage or medical therapy. Surgery is still the treatment of choice and can be performed by the conventional or laparoscopic approach. Percutaneous drainage and treatment of the cyst with hypertonic saline or alcohol seems to be a good alternative to surgery in selected cases. Currently, we treat types I and II by ultrasound-guided percutaneous drainage and types IV and V (excluding totally calcified cysts) surgically. Type III cysts can be managed either way depending on the presence of drainable content. We believe that the laparoscopic approach should be limited to noncomplicated cysts. Hydatid disease is still endemic in various areas of the world. The cystic form, due to Echinococcus granulosus, affects the countries of the Mediterranean, Middle East, and South America more often than in other parts of the world, but migration among continents, has led to the disease being prevalent in other countries as well. The liver is reported to be the most commonly involved organ (in 52–77% of cases) [1]. Non-complicated hydatid cysts of the liver are asymptomatic. The symptoms may be related to a toxic reaction due to the presence of the parasite or the local and mechanical effects depending on the location and nature of the cysts and the presence of complications [2].


Clinical Biochemistry | 2000

Coenzyme Q10 concentrations and antioxidant status in tissues of breast cancer patients.

Oytun Portakal; Özay Özkaya; Mine Erden i̇nal; Berrin Bozan; MüBerra Koşan; Iskender Sayek

OBJECTIVES An increasing amount of experimental and epidemiological evidence implicates the involvement of oxygen derived radicals in the pathogenesis of cancer development. Oxygen derived radicals are able to cause damage to membranes, mitochondria, and macromolecules including proteins, lipids and DNA. Accumulation of DNA damages has been suggested to contribute to carcinogenesis. It would, therefore, be advantageous to pinpoint the effects of oxygen derived radicals in cancer development. DESIGN AND METHODS In the present study, we investigated the relationship between oxidative stress and breast cancer development in tissue level. Breast cancer is the most common malignant disease in Western women. Twenty-one breast cancer patients, who underwent radical mastectomy and diagnosed with infiltrative ductal carcinoma, were used in the study. We determined coenzyme Q10 (Q) concentrations, antioxidant enzyme activities (mitochondrial and total superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase), and malondialdehyde (MDA) levels in tumor and surrounding tumor-free tissues. RESULTS Q concentrations in tumor tissues significantly decreased as compared to the surrounding normal tissues (p < 0.001). Higher MDA levels were observed in tumor tissues than noncancerous tissues (p < 0.001). The activities of MnSOD, total SOD, GSH-Px and catalase in tumor tissues significantly increased (p < 0.001) compared to the controls. CONCLUSIONS These findings may support that reactive oxygen species increased in malignant cells, and may cause overexpression of antioxidant enzymes and the consumption of coenzyme Q10. Increased antioxidant enzyme activities may be related with the susceptibility of cells to carcinogenic agents and the response of tumor cells to the chemotherapeutic agents. Administration of coenzyme Q10 by nutrition may induce the protective effect of coenzyme Q10 on breast tissue.


Surgery Today | 2004

Cystic hydatid disease: current trends in diagnosis and management.

Iskender Sayek; M. Bulent Tirnaksiz; Riza Dogan

Cystic echinococcosis is endemic in certain parts of the world. The growth of the cyst is often slow, and the liver and lungs are the most frequently involved organs. Diagnosis is based on clinical signs and symptoms and epidemiological data, while ultrasonography is important for the classification of hydatid cysts. Although certain types of hydatid cysts are successfully treated by percutaneous aspiration, injection, and reaspiration, surgery remains the treatment of choice. We reviewed the current trends in the diagnosis and management of cystic echinococcosis, with special emphasis on hepatic and pulmonary involvement.


American Journal of Surgery | 2002

Surgical treatment of hydatid cysts of the liver in the era of percutaneous treatment

Kaya Yorganci; Iskender Sayek

BACKGROUND Although surgery is the recommended treatment for liver hydatid disease, percutaneous treatment has been introduced as an alternative to surgery. No previous studies have been reported for patients who have not been suitable for percutaneous treatment and undergone surgery. The aim if this study was therefore to evaluate the patients who have liver hydatid disease and not suitable for percutaneous treatment and to determine the effectiveness of different types of surgical interventions in these patients. PATIENTS AND METHODS Ninety-five patients who underwent operations for liver hydatid disease were retrospectively reviewed. All patients were radiologically evaluated before surgery for possible percutaneous treatment. Besides other related factors, conventional and radical surgical approaches were compared in terms of complication and recurrence rate. RESULTS Overall complication and recurrence rates were 40% and 25%, respectively. Conventional surgical approaches and common bile duct exploration were significantly associated with an increased complication and recurrence rate. CONCLUSIONS Selection of simple liver hydatid cysts for percutaneous treatment had led us to operate more difficult and complicated cases. It seems that routine use of endoscopic retrograde cholangiography in the preoperative period and more efforts to perform radical procedures are two major determinants in the successful treatment of theses complicated cases.


American Journal of Surgery | 1999

Effect of persistently elevated intraabdominal pressure on healing of colonic anastomoses

Murat Kologlu; Iskender Sayek; L.Bilkay Kologlu; Demirali Onat

BACKGROUND The adverse effects of elevated intraabdominal pressure (IAP) on abdominal organs are realized, but its influence on anastomotic healing has not been studied. The aim of this study was to evaluate the effect of elevated IAP on healing of colonic anastomoses. METHODS Thirty rats, which all had right colonic anastomoses, were divided into five groups. Group 1 was the control group, and group 2 had fecal peritonitis. IAP was maintained between 4 to 6 mm Hg in group 3, 8 to 12 mm Hg in group 4, and 14 to 18 mm Hg in group 5 until all rats were sacrificed on day 4. Bursting pressures and tissue hydroxyproline concentrations of anastomoses were then analyzed and compared. RESULTS Mean +/- SEM of bursting pressures were 143+/-2.9 mm Hg in group 1, 72+/-14.4 mm Hg in group 2, 77.3+/-7.9 mm Hg in group 3, 57.5+/-11.2 mm Hg in group 4, and 40.1+/-9.6 mm Hg in group 5 (P<0.0001, one-way analysis of variance [ANOVA]). Mean +/- SEM of tissue hydroxyproline concentrations were 5.3+/-0.3 microg/mg in group 1, 4.7+/-0.5 microg/mg in group 2, 4.6+/-0.6 microg/mg in group 3, 3.6+/-0.5 microg/mg in group 4, and 2.4+/-0.2 microg/mg in group 5 (P = 0.0026, one-way ANOVA). The bursting pressure and hydroxyproline concentrations had good correlation (P<0.001, r = 0.76). CONCLUSIONS Elevated IAP delays healing of colonic anastomoses and 4 to 6 mm Hg IAP delays healing as much as fecal peritonitis. More elevated IAP delays healing more than fecal peritonitis. These events may be clinically important and may result from local-systemic effects of IAP.


World Journal of Surgery | 1997

Effects of Polyglycolic Acid and Polypropylene Meshes on Postoperative Adhesion Formation in Mice

Atac Baykal; Demirali Onat; Kemal Rasa; Nurten Renda; Iskender Sayek

Abstract The purpose of this study was to investigate the effects of polyglycolic acid (PGA), an absorbable (ABS) mesh, and polypropylene (PP), a nonabsorbable (NA) mesh, on intestinal adhesion formation. Altogether 72 mice were divided into a control group of 24, an ABS mesh group of 23, and an NA mesh group of 25. All three groups were divided into two subgroups for evaluation of adhesion severity at postoperative (po) days 5 and 90. Adhesion severity was measured with adhesion grading and tissue hydroxyproline (OHP) levels. Adhesion degree was minimal (1) in all subjects on day 5. Also there was no difference in tissue OHP levels between three groups on day 5 ( p > 0.05). Adhesion degree and tissue OHP levels as determinants of adhesion severity were higher in the PGA mesh group than the control group and the PP mesh group on day 90 (p < 0.001). There was no difference between the control group and the PP mesh groups (p > 0.05). Adhesion degree was higher on day 90 than on day 5 in the control group and the PGA mesh group (p < 0.05), whereas tissue OHP level was higher on day 90 than on day 5 in all three groups (p < 0.001). Also there was linear correlation between adhesion degree and tissue OHP levels (r= 0.86, p < 0.001). The study demonstrates that ABS PGA mesh has higher potential for adhesion formation than the NA PP mesh, probably related to the increased foreign body and inflammatory reactions during the absorption process of the mesh.


American Journal of Surgery | 1998

An experimental study of the effect of aprotinin on intestinal adhesion formation.

Yusuf B. Ozogul; Atac Baykal; Demirali Onat; Nurten Renda; Iskender Sayek

BACKGROUND Depression of fibrinolysis is known to be a major mechanism for postoperative adhesion formation. Because aprotinin inhibits fibrinolysis it may lead to an increase in adhesion formation whereas its anti-inflammatory effects may lead to a decrease in adhesion formation. Our aim is to clarify conflicting results in previous literature. METHODS Basal levels of intestinal hydroxyproline (OHP) content and local fibrinolytic activity (LFA) were determined using naive groups. In the experiment groups, adhesions were created by scraping and creating a transient ischemia of a segment of terminal ileum. Group I and II rats were injected subcutaneous (s.c.) normal saline (NS) for 3 days and single dose intraperitoneal (i.p.) NS, respectively. Group III and IV rats were injected s.c. aprotinin for 3 days and single dose i.p. aprotinin, respectively. Group V rats were injected intramuscular methylprednisolone (MP) for 3 days. LFA and OHP levels were determined on the second and fifth postoperative days. The severity of adhesion formation was graded on the fifth day. RESULTS Aprotinin decreased both the severity of adhesions and OHP levels whereas MP decreased only the severity of adhesions. There was an early depression of LFA at the second day in both NS and MP groups increasing to basal levels at the fifth day. OHP levels showed significant correlation with adhesion severity. CONCLUSION Results showed that aprotinin decreased intra-abdominal adhesion formation probably by preventing early depression of LFA.


Medical Teacher | 2009

Metacognitive awareness and self-regulated learning skills of medical students in different medical curricula

Sevgi Turan; Özcan Demirel; Iskender Sayek

Aim: The aim of this study was to investigate the acquisition of metacognitive awareness and self-regulated learning skills in medical schools using different curricular models. Methods: The study was carried out in four medical schools implementing different curricular models. Eight hundred and sixty two medical students took part in the study and two scales (self-regulated learning perception scale – SRLPS and metacognitive awareness inventory – MAI) were used. Cronbachs alpha was 0.93 for the MAI, and 0.88, 0.91, 0.83, and 0.76 for the four dimensions of the SRLPS. Results: There were no statistically significant differences in MAI scores according to gender, curricular language, or previous exposure or not to a learner-centered method during secondary school, but the differences in scores according to the phase and curricular model were found to be significant. With regard to SRLPS total scores, no difference was found according to gender, but significant differences were found according to phase, curricular language, and curricular model. MAI and SRLPS scores of students from the medical school using a learner-centered curriculum were higher than the other schools’ students. Conclusion: This study suggests that students who experience a learner-centered curriculum, such as PBL during their medical education demonstrate improved metacognitive awareness and self-regulated learning skills.


The American Journal of Gastroenterology | 1998

Arterial thrombosis leading to intestinal infarction in a patient with Behçet’s disease associated with protein C deficiency

Yusuf Bayraktar; Ali Riza Soylu; Ferhun Balkanci; Gokhan Gedikoglu; Metin Cakmakci; Iskender Sayek

Behçets disease may be a possible cause of both occlusive and aneurysmal arterial involvement as well as recurrent venous thrombosis. A case of Behçets disease complicated with vascular involvement leading to intestinal infarction is presented. A 41-yr-old man suffering from Behçets disease for 15 yr presented with a 2-day history of severe abdominal pain and bloody diarrhea. Intestinal infarction secondary to thrombosis of the superior mesenteric artery had been diagnosed during surgical exploration 3 yr previously. He was started on anticoagulation with nutritional support. The patient was readmitted with severe diarrhea and malabsorbtion symptoms 3 yr after intestinal resection. A thrombus located in the posterior wall of the infrarenal portion of aorta was detected by aortography and ultrasonography. Although thrombosis is a relatively common complication of Behçets disease caused by vasculitis, protein C deficiency, which is a pertinent laboratory finding in this case, might be a secondary factor in the thrombotic event. This is the first case reported of mesenteric artery thrombosis leading to bowel infarction and abdominal aorta thrombosis associated with protein C deficiency.


European Journal of Surgery | 2000

Melatonin modulates mesenteric blood flow and TNFalpha concentrations after lipopolysaccharide challenge.

Atac Baykal; Alper B. Iskit; Erhan Hamaloglu; M. Oguz Guc; Gulsen Hascelik; Iskender Sayek

OBJECTIVE To investigate the effect of various doses of melatonin on reduction in mesenteric blood flow (MBF) and increase in tumour necrosis factor alpha (TNFalpha) concentration caused by injection of lipopolysaccharide (LPS). DESIGN University Hospital, Turkey. SETTING Open experimental study. ANIMALS 59 Swiss albino mice. INTERVENTIONS Animals were injected with melatonin solvent or 1, 10, 100, or 500 mg/kg melatonin. Ten minutes later control animals were injected with saline, and the experimental group with LPS. MAIN OUTCOME MEASURES Mesenteric blood flow and serum TNFalpha concentration. RESULTS In control animals, 100 and 500 mg/kg melatonin reduced MBF. LPS reduced MBF in solvent, 1, and 10 mg/kg melatonin groups. The concentration of TNFalpha was considerably increased in the mice given LPS. Melatonin reduced this response significantly. CONCLUSION In high doses melatonin directly reduces MBF. It has no protective effect on the LPS-induced decrease in MBF. In lower doses it blocks, but at higher doses reduces, LPS-induced TNFalpha production.

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