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Dive into the research topics where Orhan Kozak is active.

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Featured researches published by Orhan Kozak.


American Journal of Nephrology | 2005

Assessment of oxidative stress in the early posttransplant period: comparison of cyclosporine A and tacrolimus-based regimens.

Abdulgaffar Vural; Mahmut Ilker Yilmaz; Kayser Caglar; Ahmet Aydin; Alper Sonmez; Tayfun Eyileten; Cengizhan Acikel; Bülent Güleç; Orhan Kozak; Köksal Öner

Background: Oxidative stress is one of the leading causes of cardiovascular morbidity and mortality in chronic kidney disease. Although it is clear that many metabolic abnormalities improve, the effects of kidney transplantation on oxidative state are obscure. Methods: Twenty-three kidney transplant patients were included in the study. Eleven patients (mean age 27.9± 9.1 years) were treated with cyclosporine A (CsA) whereas 12 patients (mean age 22.4 ± 3.4 years) were treated with tacrolimus. Twenty-three healthy subjects served as controls. None of the patients or controls suffered from diabetes mellitus or an acute infection at the time of the study. Plasma malondialdehyde (MDA), plasma selenium (Se), erythrocyte glutathione peroxidase (GSH-Px), erythrocyte superoxide dismutase (SOD), erythrocyte Zn (EZn), and erythrocyte Cu (ECu) levels were studied before and in the 1st,3rd, 7th, 14th and 28th days after the transplantation. Results: The GSH-Px, SOD, ECu, EZn and selenium levels were lower and MDA levels were higher in patients than controls before transplantation (p < 0.001 for all). MDA levels decreased and SOD, GSH-Px, ECu, EZn levels increased in parallel to the decrement of serum creatinine levels following the renal transplantation. No difference was found among the patients regarding the treatment regime. Conclusion: The study data suggest that the improvement in oxidative state parameters begins at the first day of renal transplantation and continues at the 28th posttransplant day in living donor transplantations.


American Journal of Emergency Medicine | 2008

Late presentation of blunt right diaphragmatic rupture (hepatic hernia)

Orhan Kozak; Öner Menteş; Ali Harlak; Taner Yigit; Zafer Kilbas; Ismail Aslan; Murat Akin; Ugur Bozlar

Diaphragmatic rupture occurs in 0.8% to 3.6% of patients after blunt or penetrating thoracoabdominal trauma, and the preoperative diagnosis is difficult. The diagnosis of traumatic diaphragmatic rupture may be made on initial presentation or at any time later. Right-sided diaphragmatic rupture is rare and occurs in approximately 5% to 20% of all diaphragmatic disruptions. The incidence of herniation of the intra-abdominal organs into the pleural cavity is also low, observed in only about 19% of right-sided diaphragmatic ruptures. We present a case of right-sided traumatic rupture of the diaphragm diagnosed 15 years after the initial blunt trauma. A 22-year-old male patient fell 15 years before and was symptom-free since then. He was referred to our hospital with the signs of herniation of the right diaphragm, which was manifested in the chest x-rays. The definite diagnosis was made through thoracoabdominal computed tomography. The diaphragmatic rupture was repaired via abdominal approach.


Clinics | 2009

Ultrasonography accurately evaluates the dimension and shape of the pilonidal sinus.

Öner Menteş; Aslı Oysul; Ali Harlak; Nazif Zeybek; Orhan Kozak; Turgut Tufan

PURPOSE To study the benefits of ultrasonography for detecting the borders of pilonidal sinus tissue. The correlation between physical and ultrasonographic examination was used for surgical planning. METHOD Between April and December 2004, 73 patients were recruited for this study. All patients were examined, and the borders of the sinus tissue were marked on the skin according to palpation before surgery. The surgeon also made a treatment plan considering the diseased tissue and marked a possible incision line. Patients were subsequently examined with ultrasonography. According to the ultrasonographic evaluation, the margins, extensions, and openings of pilonidal sinus tissue were determined and marked on the patient in a different color by a radiologist prior to surgery. The most suitable surgical treatment was decided according to the information obtained by ultrasonography. RESULTS The average age was 23.03 ± 3.05 (range 18–39) years. We found 81 lesions in 73 patients. Ultrasonographic borders of sinus tissue were similar to the borders marked by the surgeon in 56 patients (76.7%). In the remaining 17 patients (23.3%), ultrasonography detected branches or borders that distinctly exceeded the planned incision line. After ultrasonographic examination, the surgeon changed his incision line in 14 patients and the surgical intervention in 3 patients. CONCLUSION Palpation and methylene blue injection do not provide appropriate information in many patients. Our study revealed that pre-operative ultrasonography can improve the identification of the sinus tract and its branches when compared to palpation and methylene blue injection.


International Journal of Surgery | 2013

Surgical treatment of caustic esophageal strictures in adults

Ali Harlak; Taner Yigit; Kagan Coskun; Tahir Özer; Öner Menteş; Bülent Güleç; Orhan Kozak

BACKGROUND AND AIMS Caustic esophageal injury is a rare clinical condition in adult patients. Although dilatation, or the conservative approach, is the primary treatment method, some patients require surgical intervention. Because of the rarity of such cases, standard surgical treatment algorithms cannot be utilized. In this article, we present our surgical experience and discuss the challenges in the surgical management of corrosive injury of the esophagus in adults. METHODS A retrospective review was conducted of 28 patients who suffered from a corrosive esophageal injury between 1996 and 2011. Patient demographics, history of corrosive material ingestion, preoperative findings, treatment strategy, operative technique, postoperative course, requirements for further treatment, and the current status of the patients were investigated. RESULTS All patients underwent a transhiatal esophagectomy in addition to a gastric pull-up with a cervical esophagogastrostomy. The mean follow-up time was 62 (12-140) months. One patient developed a deep surgical infection; anastomotic stenosis was noted and treated with dilatation in 13 patients. The mean time period between the operation and the first dilatation for 12 patients was 81 (45-161) days. The mean dilatation count for the patients was 3 (1-10). CONCLUSION Although it comes with high anastomotic stenosis rates, transhiatal esophagectomy and gastric pull-up with cervical anastomosis is a safe procedure, which can be performed for the treatment of corrosive esophageal stricture.


American Journal of Emergency Medicine | 2009

The importance of urine 5-hydroxyindoleacetic acid levels in the early diagnosis of acute appendicitis

Öner Menteş; Mehmet Eryilmaz; Ali Harlak; Halil Yaman; Taner Yigit; Önder Öngörü; Müjdat Balkan; Orhan Kozak; Turgut Tufan

PURPOSE Acute appendicitis is one of the most common surgical emergencies. Diagnosis is usually made depending on the presenting history, clinical evaluation, and laboratory tests. The aim of this study was to investigate the role of urinary 5-hydroxyindoleacetic acid (U-5-HIAA) in the early diagnosis of acute appendicitis. METHODS Thirty-five pigmented male rabbits were divided into 5 groups. Group 1 is the control (n = 7); group 2 is the sham (n = 10). The appendix was ligated from its base, and an appendectomy was performed after 12, 24, 36 hours in group 3 (n = 7), group 4 (n = 7), and group 5 (n = 7), respectively. Spot urine samples were obtained for U-5-HIAA determination, and appendectomy tissues were examined histopathologically. RESULTS Acute appendicitis was diagnosed in all animals in group 3, group 4, and group 5, and the mean levels of U-5-HIAA in group 3 were higher than in the other groups. The mean of U-5-HIAA levels between animals with appendicitis and those without showed a significant difference (P = .003). The U-5-HIAA cutoff point of 4.15 mg/g creatinine had a sensitivity of 85%, a specificity of 64.29%, and an accuracy of 76% (area under curve = 0.805) for acute appendicitis. The probability of acute appendicitis is found to be 10, 2 times more when the U-5-HIAA level is greater than 4.15 mg/g creatinine. CONCLUSION We have concluded that spot U-5-HIAA level increases significantly in the early stages of acute appendicitis.


Transplantation Proceedings | 2011

Is Removal of the Stent at the End of 2 Weeks Helpful to Reduce Infectous or Urologic Complications After Renal Transplantation

Ali Kagan Coskun; Ali Harlak; Tahir Özer; T. Eyitilen; Taner Yigit; Sezai Demirbas; Ali İhsan Uzar; Orhan Kozak; Sadettin Cetiner

OBJECTIVE Ureteral stents are used to reduce urologic complications after renal transplantation. However, they predispose to infection. The optimal time to keep them in the urinary tract has not yet been defined. The aim of this study was to evaluate the effect of early removal at the end of 2 weeks on urinary tract infections and early urologic complications (within 3 months), such as ureteroneocyctostomy leakage as well as ureteral anastomosis stricture or obstruction. METHODS We retrospectively analyzed the medical records of 48 patients who underwent renal transplantation using a ureteral stent. The patients were divided into two groups according to the time of stent removal: at the end of 2 weeks (group A; n = 10) versus at a later time (group B; n = 38). RESULTS The urologic complication rate was 0% in group A and the urinary tract infection rate, 2%. The urologic complication rate was 0% in group B and the urinary tract infection rate, 35%. CONCLUSION Early removal of the stent at the end of 2 weeks after renal transplantation is decreased the rate of urinary tract infections.


Acta Chirurgica Belgica | 2007

Larrey hernia complicated with colonic obstruction in a 77-year-old woman: a case report.

Öner Menteş; Müjdat Balkan; Kesim E; Mehmet Eryilmaz; Bozlar U; Senocak R; Orhan Kozak; Tufan T

Abstract Congenital Larrey hernia has a rare incidence and is frequently diagnosed in the later decades of life. This case study presents a 77-year-old woman with Larrey hernia and an intestinal obstruction complication, treated with laparatomic surgery.


American Journal of Emergency Medicine | 2009

Can D-dimer become a new diagnostic parameter for acute appendicitis?

Öner Menteş; Mehmet Eryilmaz; Ali Harlak; Tahir Özer; Müjdat Balkan; Orhan Kozak; Turgut Tufan

INTRODUCTION In this study, we investigated D-dimer serum level as a diagnostic parameter for acute appendicitis. MATERIALS AND METHODS Forty-nine patients were enrolled in the study. Patients were classified according to age; sex; duration between the beginning of pain and referral to a hospital or clinic; Alvarado scores; and in physical examination, presence of muscular defense, the number of leukocytes, preoperative ultrasonography, and D-dimer levels of histopathologic study groups were analyzed. RESULTS Of the patients enrolled in the study, 26.5% were females and 73.5% males. The average age was 21 years (range, 16-38 years) and 81.7% acute appendicitis (AA). According the duration of pain, 63.2% of the patients were referred to the hospital within the first 24 hours, 26.5% of the patients were referred to the hospital within 24 to 48 hours, and 10.3% were referred to the hospital within a period of more than 48 hours. No statistically significant difference was determined regarding D-dimer levels between the histopathologic study groups (P > .05). Alvarado scores lower than 7 were found in 36.7% and 7 or higher in 63.3% of the patients. There was no statistically significant difference related with D-dimer levels between histopathologic study groups (P > .05). The ratio of cases with a number of leukocytes below the upper limit were determined respectively as 32.7% and 67.3%, and no statistically significant difference was found regarding d-dimer levels between histopathologic study groups (P > .05). CONCLUSION Increased D-dimer levels should not be considered as a diagnostic parameter in diagnosis of acute appendicitis.


Acta Chirurgica Belgica | 2011

Effects of Prevention of Oxidative and Nitro-Oxidative Stress on Experimental Rat Colon Anastomosis using Acetylcysteine, Ebselen and 1400w

Y. Poyrazoglu; Taner Yigit; Ali Harlak; Öner Menteş; Semih Gorgulu; Ali İhsan Uzar; Orhan Kozak

Abstract Oxygen radicals and radicals derived from nitrogen metabolism are important in wound and anostomotic healing. In particular, nitrous oxide, originating from induced nitrous oxide synthetase, retards the wound healing process by producing peroxynitride. Therefore induced nitric oxide synthase (INOS) inhibitors and peroxynitride cleansing agents seem helpful in promoting healing. The purpose of this study was to investigate the effects of N-acetylcysteine (antioxidant), ebselen (peroxynitride cleansing agent) and 1400w (INOS inhibitor) on experimental colonic anastomot-ic wound healing. Material and methods: 45 randomized Sprague-Dawley rats received colonic anastomosis, and all animals were treated for four days with drugs specific for each group except for the sham and control groups. All rats were given a relaparatomy on the fifth day of the study and evaluated for study parameters indicating anastomotic healing, burst pressure, tissue malondialdehit (MDA), superoxide dismutase (SOD), glutathione peroxidase (GPx) and hydroxyproline (OH-proline). Results: when compared to the control group, increased (p < 0.01) burst pressure, OH-proline and decreased MDA, and SOD levels were noted in the 1400w group. Furthermore, the GPx levels were higher (p < 0.05) in rats given NAC therapy. Conclusions: the positive results of selective INOS inhibition using 1400w in this study confirm the adverse effects of the INOS enzyme on anastomotic wound healing. Therefore, we have concluded that 1400w may be helpful in promoting anastomotic healing.


Indian Journal of Surgery | 2015

The Effects of Total Colectomy on Bacterial Translocation in a Model of Acute Pancreatitis

Rahman Şenocak; Taner Yigit; Zafer Kilbas; Ali Kagan Coskun; Ali Harlak; Mustafa Öner Menteş; Abdullah Kilic; Armagan Gunal; Orhan Kozak

Prevention of secondary infection is currently the main goal of treatment for acute necrotizing pancreatitis. Colon was considered as the main origin of secondary infection. Our aim was to investigate whether prophylactic total colectomy would reduce the rate of bacterial translocation and infection of pancreatic necrosis. Forty-two Sprague–Dawley rats were used. Pancreatitis was created by ductal infusion of sodium taurocholate. Rats were divided into four groups: group-1, laparotomy + pancreatic ductal infusion of saline; group-2, laparotomy + pancreatic ductal infusion of sodium taurocholate; group-3, total colectomy + pancreatic ductal infusion of saline; and group-4, total colectomy + pancreatic ductal infusion of sodium taurocholate. Forty-eight hours later, tissue and blood samples were collected for microbiological and histopathological analysis. Total colectomy caused small bowel bacterial overgrowth with gram-negative and gram-positive microorganisms. Bacterial count of gram-negative rods in the small intestine and pancreatic tissue in rats with colectomy and acute pancreatitis were significantly higher than in rats with acute pancreatitis only (group-2 versus group-4; small bowel, p = <0.001; pancreas, p = 0.002). Significant correlation was found between proximal small bowel bacterial overgrowth and pancreatic infection (r = 0,836, p = 0.001). In acute pancreatitis, prophylactic total colectomy (which can mimic colonic cleansing and reduction of colonic flora) induces small bowel bacterial overgrowth, which is associated with increased bacterial translocation to the pancreas.

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Öner Menteş

Military Medical Academy

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Taner Yigit

Military Medical Academy

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Ali Harlak

University of Pittsburgh

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Müjdat Balkan

Military Medical Academy

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Turgut Tufan

Military Medical Academy

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Zafer Kilbas

Military Medical Academy

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Ali Harlak

University of Pittsburgh

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