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Featured researches published by Taner Koçak.


Urologia Internationalis | 2004

Urological and Surgical Complications in 362 Consecutive Living Related Donor Kidney Transplantations

Taner Koçak; I. Nane; Haluk Ander; Orhan Ziylan; Tayfun Oktar; Cavit Ozsoy

Objective: The aim of this study is to review retrospectively the surgical and urological complications encountered in 362 cases of living related donor kidney transplantations (LRDTs). Material and Methods: Between 1983 and 2002, 362 consecutive LRDTs were performed at our institution. The urological and surgical complications were determined in these cases. Results: Overall, urological and surgical complications were encountered in 57 (15.7%) of the renal transplants. Of the 362 patients, urological complications were detected in 29 of them (8.01%), including 5 urinary fistula (with 1 distal ureteral necrosis), 2 ureteric stenosis, 1 renal calculi, 8 symptomatic vesicoureteral reflux and 13 lymphocele requiring intervention. Vascular complications were developed in 5 patients such as renal vein thrombus in 1 and renal arterial stenosis in 4 cases. Wound infection was detected in 6 patients. Fourteen patients underwent surgical explorations due to perinephric hematoma during the early postoperative period. Renal allograft rupture due to accelerated rejection was developed in 2 cases. A lower segmental arterial injury occurred in 1 patient during the operation. Conclusion: LRDT is an important treatment alternative for patients with end-stage renal disease. Many complications may occur after renal transplantations. Our rate of complications is within the range of the current literature. After a modification of our surgical technique, as not dissecting the external iliac artery, the number of lymphoceles has decreased dramatically and with using ureteric stents, we detected a significant decrease in urinary complication rates.


Urologia Internationalis | 2000

Urologic Complications of Extravesical Ureteroneocystostomy in Renal Transplantation from Living Related Donors

I. Nane; Teoman Cem Kadioglu; Ahmet Tefekli; Taner Koçak; Haluk Ander; Türker Köksal

Introduction: Reconstruction of the urinary system during renal transplantation is usually performed with antirefluxive ureteroneocystostomy techniques and extravesical methods are usually preferred. Material and Methods: Between 1983 and 1997, 241 renal transplantations from living donors were performed at our institution. A variation of the Lich-Gregoir technique was used as the ureteroneocystostomy method in all cases. Results: A total of 12 (4.9%) urologic complications were observed. Urinary fistula developed in 5 (2%) cases and were explored surgically during the early postoperative period. Postoperative vesicoureteral reflux (VUR) to the transplanted kidney was identified in 7 (2.9%) cases. Either endoscopic or surgical interventions resolved VUR in 4 cases while the other 3 did not need further treatment. No ureteral stenosis was observed. There was no loss of graft due to urologic complications. Conclusions: Urologic complications after renal transplantation are reported to be about 7% and ischemia is blamed as the major contributing factor. Preparation of the native ureter during donor nephrectomy and preservation of distal periureteral fatty tissue, anastomosis technique variations in vascular anatomy, rejections and medications are the major factors determining the ischemia.


The Journal of Urology | 2006

The Impact of Late Presentation of Posterior Urethral Valves on Bladder and Renal Function

Orhan Ziylan; Tayfun Oktar; Haluk Ander; Esat Korgali; Hasan Rodoplu; Taner Koçak

PURPOSE We retrospectively reviewed the records of patients with late presentation of PUVs, and compared bladder and renal function to that in patients with an early diagnosis of PUVs. MATERIALS AND METHODS We retrospectively reviewed the charts of 36 males (mean age at diagnosis 8.8 years, range 5 to 14) with late presentation of PUVs who were treated at our institution between 1986 and 2004. Of these patients 20 had undergone urodynamic evaluation during followup (mean age 10.65 years, range 5 to 23). We chose as controls 19 age matched children with PUVs who were diagnosed and treated before age 5 years and underwent urodynamic evaluation during followup (mean age at urodynamic evaluation 8.52 years, range 6 to 15). Urodynamic parameters were compared between the 2 patient groups. Renal function in the late presenting cases was also compared to controls. RESULTS The most common symptoms at presentation were diurnal enuresis (17 patients, 47.2%) poor stream (7, 19.4%) and urinary retention (5, 13.9%). Overall, urodynamic bladder abnormalities were detected in 17 of 20 patients (85%), detrusor overactivity in 3 (15%), significant post-void residual in 9 (45%) and bladder capacity greater than expected for age in 9 (45%). No significant difference in bladder capacity, compliance or post-void residual was demonstrated between the late presenting and control groups. Only detrusor overactivity was significantly lower in the late presenting group (p = 0.013). After a mean followup of 67.03 months age specific creatinine levels were increased in 13 of 27 patients (48.1%), including 7 (25.9%) with ESRD. Renal function was significantly impaired in the late presenting group compared to controls (48.1% vs 13.7%, p = 0.001). CONCLUSIONS We found a significantly lower rate of detrusor overactivity (15%) in patients with late presenting PUVs. Comparison of urodynamic parameters between the early and late presenting groups did not reveal any significant difference. This similar pattern of bladder dysfunction, independent of age at relief of obstruction, may indicate a common pathophysiological etiology for bladder dysfunction in all patients with PUVs. Also, renal function was significantly impaired in the late presenting group in this series.


Journal of Renal Nutrition | 2011

Appetite-regulating Hormones in Chronic Kidney Disease Patients

Yıldız Öner-İyidoğan; Figen Gurdol; Hikmet Koçak; Pernur Öner; Pinar Cetinalp-Demircan; Yasar Caliskan; Taner Koçak; Aydin Turkmen

OBJECTIVE Inflammation and loss of appetite is the most common problem in patients with chronic kidney disease (CKD). This comparative cross-sectional study aimed to characterize the changes in circulating levels of ghrelin, obestatin, leptin, all of which have an effect on food intake, and proinflammatory cytokines interleukin (IL)-6 and tumor necrosis factor-alpha (TNF-α) in patients with CKD who were undergoing different treatments. DESIGN AND SETTING Study participants included 36 patients who had undergone hemodialysis (body mass index [BMI]: 22.3 ± 4.17 kg/m(2)); 41 who had undergone peritoneal dialysis (BMI: 23.5 ± 3.10 kg/m(2)), 30 with early stage CKD (BMI: 24.4 ± 3.32 kg/m(2)), and 31 healthy subjects (24.3 ± 2.14 kg/m(2)). The patients with CKD were kept under a standard diet with restricted salt, potassium, and protein intake. INTERVENTION Levels of leptin, acylated ghrelin, obestatin, TNF-α, and IL-6 were measured by commercially available enzyme-linked immunosorbent assay kits. Total nitrite/nitrate was analyzed using colorimetric assay kit. RESULTS Significantly high leptin levels, accompanied by low acylated ghrelin levels, were observed in patients with CKD. Maintenance dialysis did not affect these levels. TNF-α and IL-6 levels were significantly higher in CKD patients than in healthy subjects, the highest being in dialysis patients. Obestatin levels were relatively low in patients who had undergone hemodialysis. CONCLUSION Low acyl-ghrelin levels, accompanied with high levels of TNF-α and IL-6 may be involved in the loss of appetite and poor nutritional status in CKD patients.


The Journal of Urology | 1999

Evaluation and therapeutic approaches of voiding and erectile dysfunction in neurological Behçet's syndrome.

Tibet Erdoğru; Taner Koçak; Piraye Serdaroglu; Ates Kadioglu; Sedat Tellaloglu

PURPOSE Behçets syndrome is a progressive inflammatory disease which involves multiple systems. It is characterized by 3 main symptoms of iridocyclitis, and oral and genital ulcerations. Nervous system involvement is seen rarely in this clinical entity and is known as neurological Behçets syndrome. Inflammation usually occurs in the brain stem, cerebellum and medulla spinalis. Voiding and erectile dysfunction can be due to progressive inflammatory reactions in the nervous and vascular systems. We prospectively evaluated the dysfunctional bladder and penis, and therapeutic options were evaluated prospectively. MATERIALS AND METHODS A total of 24 consecutive patients diagnosed with neurological Behçets syndrome after neurological evaluation were enrolled in this study. Neurological involvement and localization of the nervous system were proved on evaluation. Voiding and erectile dysfunction was evaluated regardless of the presence of related symptoms, and the results were compared with those of controls. Patients with voiding dysfunction on urodynamic study were treated and reevaluated symptomatically after 3 and urodynamically after 6 months. RESULTS The rate of erectile dysfunction in neurological Behçets syndrome was 63%. Mixed type vasculogenic impotence, arterial insufficiency, veno-occlusive dysfunction and neurogenic impotence were identified in 7, 2, 2 and 1 patient, respectively. Detrusor instability was demonstrated in 12 patients with urgency incontinence, including 3 with detrusor-sphincter dyssynergia. Brain stem localization was determined in these patients on neurogenic evaluation. Significant improvement was observed with anticholinergic treatment and clean intermittent catheterization in 3 patients with detrusor-sphincter dyssynergia. Hypersensitive and hypocompliant detrusor was noted in patients with neurological Behçets syndrome who had normal voiding habits. CONCLUSIONS Incontinence or irritable bladder symptoms should not be considered innocuous clinical findings in neurological Behçets syndrome. Lower urinary tract function should be evaluated in all patients with this neurological syndrome. The incidence of erectile dysfunction is approximately 65% and the therapeutic approach should be determined according to lower urinary tract function.


Journal of Pediatric Urology | 2013

Urinary nerve growth factor in children with overactive bladder: A promising, noninvasive and objective biomarker

Tayfun Oktar; Taner Koçak; Yıldız Öner-İyidoğan; Selcuk Erdem; Muhammed Seyithanoğlu; Orhan Ziylan; Hikmet Koçak

OBJECTIVE This prospective study was designed to determine urinary nerve growth factor (NGF) levels in children with overactive bladder (OAB), and to evaluate whether this factor can be used as a biomarker for diagnosis and monitoring treatment outcome. PATIENTS AND METHODS Urinary NGF levels were determined in 40 children with OAB and in a control group of 20 children with no urinary symptoms. Urine samples were collected from the patients prior to and at 3 and 6 months after the beginning of treatment. The total NGF levels (pg/mL) were further normalized to the concentration of urinary creatinine (NGF/Cr level). RESULTS Overall, both NGF and NGF/Cr levels were significantly higher at the beginning of the study. Mean NGF levels were 30.75 ± 8.35 and 9.75 ± 2.11 pg/ml (p = 0.023) and mean NGF/Cr levels were 0.53 ± 0.14 and 0.16 ± 0.04 (p = 0.022) in patients and controls, respectively. After 6 months of therapy, the NGF/Cr level was significantly reduced to almost control levels (0.16 ± 0.02, p = 0.047). CONCLUSION NGF and NGF/Cr levels were significantly higher in children with OAB than controls at initial evaluation. Furthermore, the NGF/Cr level was significantly reduced following 6 months of therapy. NGF and NGF/Cr levels show promise as reliable biomarkers for OAB diagnosis and to monitor therapy in the pediatric age group.


Clinical and Experimental Medicine | 2009

Dimethylarginines and inflammation markers in patients with chronic kidney disease undergoing dialysis

Yıldız Öner-İyidoğan; Pernur Öner; Figen Gurdol; Seldag Bekpinar; Yesim Unlucerci; Yasar Caliskan; Pinar Cetinalp-Demircan; Taner Koçak; Aydin Turkmen

The aim of this study was to investigate the pro-oxidant and proinflammatory biomarkers and their relationship with dimethylarginines (DMAs) in patients at various stages of chronic kidney disease (CKD). We studied 114 CKD patients, 36 were hemodialyzed, 41 peritoneal dialyzed and 37 nondialyzed (early stage) CKD patients. The control group consisted of 31 healthy subjects. Plasma levels of asymmetric dimethylarginine (ADMA), symmetric dimethylarginine (SDMA), l-arginine, nitric oxide (NO) and proinflammatory cytokines (TNF-alpha and IL-6) were determined, and their relationships with the degree of disease were evaluated. Both DMAs were at high levels in all CKD patients, whereas arginine concentrations were low in patients undergoing dialysis. Elevated TNF-α and IL-6 in CKD patients were indicative of ongoing chronic inflammatory state. A significant positive correlation between SDMA and creatinine suggests that plasma SDMA level may be an index for renal function.


Journal of Cancer Research and Clinical Oncology | 1999

Antioxidant enzyme activities and lipid peroxides in the plasma of patients with benign prostatic hyperplasia or prostate cancer are not predictive

Semra Dogˇru-Abbasogˇlu; Gülçin Aykaç-Toker; Taner Koçak; Erdinç Ünlüer; Müjdat Uysal

Abstract In this study, lipid peroxide and total sulfhydryl contents and activities of superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT) were investigated in the plasma of patients with benign prostatic hyperplasia (BPH) and prostate cancer. No significant change was found in lipid peroxidation or antioxidant systems in the plasma of patients with BPH and prostate cancer. The results indicate that evaluation of the prooxidant-antioxidant balance in the plasma of BPH and prostate cancer patients cannot be used as a marker to discriminate between these diseases.


Clinical and Experimental Medicine | 2005

Cystatin-C and creatinine as indices of glomerular filtration rate in the immediate follow-up of renal transplant patients.

Yıldız Öner-İyidoğan; Figen Gurdol; Taner Koçak; I. Nane; Sema Genc

Serum cystatin-C (cys-C), creatinine (Cr), C-reactive protein (CRP) and amyloid A have been shown to provide useful information for renal function following transplantation. In this study, we wanted to evaluate the impact of these parameters as markers of the glomerular filtration rate (GFR) on the third and seventh days of the post-transplantation period. Cys-C was determined by the particle-enhanced immunoturbidimetric assay, and serum amyloid A (SAA) by the sandwich-enzyme immunoassay kit. Cr and CRP concentrations were measured by the Cobas Integra 400 autoanalyser. The patients (n=35) were followed with daily repetitive measurements of serum Cr and urine output per hour, and with Doppler ultrasonography against the risk of rejection. Statistical evaluations were made using the ANOVA and Pearson’s test. Serum cys-C and Cr levels on both the 3rd and 7th days after transplantation were lower than those of pretransplantation values (P<0.001). The Cr/cys-C ratio was decreased on the 3rd day of the post-transplantation period, and kept declining on the 7th day. This ratio was high only in the patient with an acute rejection episode. None of the patients with high pretransplant CRP levels had a rejection episode during a six-month follow-up. SAA concentrations were found to be higher than the pretransplant values in the early post-transplant period. Cys-C had good sensitivity to estimate the renal function in the very early period of transplantation, but its value as a marker of GFR was decreased at the end of first week. As none of the 34 patients had a rejection episode, the observed rise in SAA and CRP levels is not specific to rejection.


Urology | 1997

Primary gonadotropin releasing hormone and adjunctive human chorionic gonadotropin treatment in cryptorchidism: A clinical trial

I. Nane; Orhan Ziylan; Tarik Esen; Taner Koçak; Haluk Ander; Sedat Tellaloglu

OBJECTIVES The effect of intranasal gonadotropin-releasing hormone (GnRH) and intramuscular human chorionic gonadotropin (hCG) in the treatment of cryptorchidism was investigated in 48 prepubertal boys. METHODS Forty-eight prepubertal boys with 70 undescended testes were enrolled into a prospective study between November 1989 and November 1991. GnRH was applied as nasal spray at a dose of 1.2 mg/day for 4 weeks. The patients with partial descent were subsequently treated with 1500 IU hCG weekly for 3 weeks. RESULTS Complete descent was observed in 53% (37 of 70) of testes; 58% (15 of 26) in unilateral and 50% (22 of 44) in bilateral undescended testes. One abdominally located testicle did not respond to therapy. Of 37 testes located in the inguinal canal, seven (19%) descended. On the other hand, descensus rates were 100% for the testes located at the external inguinal ring and at a high scrotal level. Six primarily descended testes (16%) showed relapse during the follow-up. Surgery was performed in 12 patients (14 testes), revealing associated hernia in nine testes and epididymal anomalies in four. CONCLUSIONS We believe that the GnRH and hCG combination is an effective therapy for undescended testes located at and beyond the external inguinal ring and should be the first treatment choice because of its noninvasiveness. Both unilateral and bilateral undescended testes responded with similar success rate to hormonal therapy. Surgery should be considered for proximal cryptorchidism.

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