S. Aktas

Medipol University, İstanbul, Istanbul, Turkey

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Publications (23)47.43 Total impact

  • S. Aktas · S. Sevmis · S. Ozgur · C. Erol · H. Karakayali
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    ABSTRACT: Living-donor liver transplantation (LDLT) with the use of a partial liver graft was established as an option to overcome the donor pool shortage, especially in developing countries. When right-lobe grafts are used for LDLT, appropriate venous drainage of the anterior segment is critical for maximizing the graft capacity. Here, we report a successful LDLT case using a right-lobe graft with 4 hepatic veins that were anastomosed separately to obtain adequate blood flow through the vena cava.
    No preview · Article · Dec 2015 · Transplantation Proceedings
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    ABSTRACT: Hepatocellular carcinoma (HCC) is one of the rare tumors with well-defined risk factors. The multifactorial etiology of HCC can be explained by its complex molecular pathogenesis. In the current study, the methylation status of 7 genes involved in DNA repair mechanisms, namely MLH1, PMS2, MSH6, MSH2, MGMT, MSH3, and MLH3, was investigated in tumor samples from HCC patients, using the methylation-specific-multiplex ligated probe amplification method and the results were correlated with available clinical findings. The most common etiological factor in these cases was the presence of hepatitis B alone (47.2%). Among the 56 cases that were studied, promoter methylation was detected in at least one of the genes in 27 (48.2%) cases, only in 1 gene in 13 (23.2%) cases, and in >1 gene in 14 (25%) cases. Of the 7 genes investigated, methylation was most frequently observed in MSH3, in 14 (25%) cases. Methylation of at least 1 gene was significantly more frequent in patients with single tumors than multifocal tumors. There were significant differences regarding hepatitis B status, Child Class, tumor number, grade, and TNM stage in cases where PMS2 methylation was detected. Our results suggest that methylation of genes involved in mismatch repair may be responsible in the pathogenesis of HCC, and evaluating changes in multiple genes in these pathways simultaneously would be more informative. Despite being a robust and relatively inexpensive method, the methylation-specific-multiplex ligated probe amplification assay could be more extensively applied with improvements in the currently intricate data analysis component.
    No preview · Article · Nov 2013 · Diagnostic molecular pathology: the American journal of surgical pathology, part B
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    ABSTRACT: Objectives: Rituximab is a monoclonal antibody directed against the CD20 molecule on pre-B and mature B cells and is used in transplant recipients for the prevention and treatment of alloantibody-mediated rejection or for the treatment of disease recurrence after transplant. In most patients, rituximab has been safe and well-tolerated, but the long-term adverse effects of rituximab are currently unknown. Materials and methods: We retrospectively evaluated 78 pediatric renal transplant recipients for the occurrence of infectious disease. Patients who received rituximab therapy were divided into 2 groups: those who developed an infection and those who did not. The 2 groups were compared for serious infections, hospitalization, graft loss, and death rates. Results: Eighteen transplant patients received rituximab therapy for various causes. The number of rituximab courses given varied according to the cause and ranged from 1 to 8 courses. The dose at each course was 375 mg/m2. Median age of all recipients was 16.00 years (min-max:, 5.00-22.00 y), and median follow-up time was 2.00 years (min-max:, 1.00-3.00 y). Serious infections (bacterial sepsis, tuberculosis, Cytomegalovirus infection, varicella-zoster virus infection, Polyomavirus-associated nephropathy, and acute pyelonephritis) were observed in 8 patients who received rituximab therapy. We observed that patients with antibody-mediated rejection had significantly increased infection rate. Patients who had used rituximab combined with antithymocyte globulin and higher rituximab course number and higher pretreatment CD19 and CD20 levels had higher risk of infection (P < .05). Conclusions: The combined use of rituximab with additional treatments such as antithymocyte globulin, intravenous immunoglobulin, and repeated plasma exchange may be associated with high risk of infectious disease. Especially for those patients who required intensive and repetitive treatment, such as antibody-mediated rejection, rituximab treatment should be used with caution. Infection risk should be closely monitored, although mainly in patients who receive T-cell-depleting agents.
    No preview · Article · Nov 2012 · Transplantation
  • M. Kirnap · S. Aktas · A. Akdur · F. Boyvat · G. Moray · M. Haberal

    No preview · Article · Nov 2012 · Transplantation
  • S. Aktas · A. Akdur · M. Kirnap · F. Ozcay · G. Moray · M. Haberal

    No preview · Article · Nov 2012 · Transplantation

  • No preview · Article · Nov 2012 · Transplantation

  • No preview · Article · Nov 2012 · Transplantation
  • A. Akdur · S. Aktas · M. Kirnap · G. Moray · M. Haberal

    No preview · Article · Nov 2012 · Transplantation
  • Umut Mousa · Sema Aktas · Halit Uner
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    ABSTRACT: Amyloidosis is characterized by accumulation of amorphous, proteinaceous material in various organs and tissues of the body. Amyloid may accumulate in the thyroid gland in cases of medullary thyroid carcinoma and systemic amyloidosis. Amyloid accumulates extracellularly in the thyroid parenchyma and disrupts the normal follicular patterns. Most of the cases reported up to now were clinically euthyroid, but many presentation forms and overlaps have been reported. Herein we present a patient with toxic nodular goiter with amyloid deposition in the toxic nodule as well as the remaining thyroid tissue.
    No preview · Article · Oct 2012 · Case Reports in Endocrinology
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    ABSTRACT: Gastrointestinal system perforations after pediatric liver transplantation Purpose: Gastrointestinal (GI) perforation is one of the causes of mortality after pediatric liver transplantation (LT). The aim of this study was to evaluate the incidence of clinical presentations, and outcomes of gastrointestinal perforations after pediatric LTs. Patients and Methods: Since September 2001, 135 pediatric LTs were performed for 132 children in our center. Four (2.6%) of these 132 children experienced GI perforation in the follow-up when analyzed retrospectively. The etiology for LT was biliary atresia in 3 children and Wilson's disease in the remaining child. Three of them had a history of portoenterostomy and 1 of them have had splenectomy before LT. Results: All perforations occurred in the first postoperative week. The patients with GI perforation were found to have fever, increased leukocyte counts, mild abdominal pain, tenderness and distention. We performed abdominal CT to all patients to diagnose the perforation. All children had Roux-en-Y hepaticojejunostomy, and perforations were not associated with the operation. The sites of perforation were at the duodenum in 1 child, at the jejunum in 2, and at the colon-hepatic flexura in the remaining 1 patient. Primary repair using two layer suture was performed in all children. We did not encounter any morbidity and mortality after operations. The operated children were followed 102, 85, 57 and 42 months, respectively. When this document was prepared, all of the 4 children were alive with good graft function. Conclusion: Among risk factors of bowel perforation, history of abdominal surgery may have a role. It should be kept in mind that, to decrease morbidity and mortality, early diagnosis is the most important factor.
    Preview · Article · Jan 2012 · Turkish Journal of Surgery
  • S Aktas · H Karakayali · G Moray · H Ozdemir · M Haberal
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    ABSTRACT: We investigated the prognostic factors affecting recurrence including Ki-67 among patients who underwent liver transplantation for hepatocellular carcinoma. The 50 patients with a diagnosis of hepatocellular carcinoma and cirrhosis included those with expanded criteria for hepatocellular carcinoma excluding subjects with major vascular invasion and metastases but not taking into account tumor size and number of tumor nodules. Twenty-eight patients had hepatocellular carcinoma characteristics outside the Milan criteria. Nineteen patients had unifocal; 31, multifocal hepatocellular carcinomas. Mean tumor size was 3.2 cm; mean tumor number was 5.06 lesions. Over a mean follow-up of 45.3±22.6 months, we diagnosed, respectively 2 recurrences. Overall 1-, 3-, and 5-year patient survival rates were 95.6%, 88.4%, and 84.8% and disease-free survival rates, 92%, 78.4%, and 71%, respectively. The independent prognostic factors by multivariate analyses were the number of tumors and Ki-67 with a cutoff value of 10%. Ki-67 staining percentage represent a marker to select recipients and to follow posttransplant recurrence.
    No preview · Article · Dec 2011 · Transplantation Proceedings
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    ABSTRACT: The incidence of detecting hepatocellular carcinoma in a removed recipient liver after a liver transplant is not rare. Here, we sought to evaluate incidental hepatocellular carcinoma at our center. Among 296 patients who had undergone a liver transplant between September 2001 and November 2010, we retrospectively analyzed the outcomes of 6 patients with incidental hepatocellular carcinoma. The proportion of incidental hepatocellular carcinoma was 2%. The rate of incidental hepatocellular carcinoma among all hepatocellular carcinoma patients is 11.5%. There were 3 children and 3 adults (mean age, 28.3 ± 26 years; age range, 1-57 years). Two of the 6 patients were 1 year old. Alpha-fetoprotein levels were mildly elevated in 3 patients. The results of preoperative imaging studies in all patients were normal, except for those that demonstrated regenerative or dysplastic nodules. One of the grafts was from a deceased donor, the remaining 5 were from living-related donors. We encountered no complications after the transplants. Pathology findings showed a mean tumor size of 0.8 ± 0.3 cm (range, 0.5-1.2 cm) and multiplicity in 1 patient. One patient with multiple tumors had microvascular invasion. According to the Tumor Node Metastasis staging system, 5 patients had Stage I, and the remaining patient had Stage II carcinoma. There were no recurrences of hepatocellular carcinoma, and no deaths occurred during a mean follow-up of 63 ± 16.5 months (range, 33-79 months). The incidence of hepatocellular carcinoma in patients with cirrhosis who have undergone a liver transplant at our hospital is similar to those reported in other studies. Incidentally found hepatocellular carcinomas showed less-invasive pathologic features and better prognoses than did preoperatively found hepatocellular carcinomas.
    No preview · Article · Jun 2011
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    ABSTRACT: Increased serum bilirubin levels are common after living-donor hepatectomy. Little information is available on the characteristics and clinical significance of serum bilirubin levels soon after donor hepatectomy. Since September 2001, we performed 229 living donor hepatectomies for living-donor liver transplantations. The 128 men and 101 women had a mean age of 34.4±8.9 years (range, 19-66). Most donors were parents (n=110; 48%). We transplanted 110 right lobes, 46 left lobes, and 73 left lateral segments. Donors were divided into 2 groups: Group 1 consisted of 181 donors who showed total bilirubin levels of <3 mg/dL, and group 2, 48 donors with levels of ≥3 mg/dL on postoperative day 3. Preoperative total bilirubin level, ratio of preoperatively estimated remnant liver volume, surgical duration, gender, age, graft type, blood transfusions, and preoperative liver biopsy findings were evaluated as risk factors for hyperbilirubinemia. The mean postoperative maximum total bilirubin level was 2.26±1.49 mg/dL (range, 0.36-9.9). Remnant liver volume<40%, preoperative bilirubin levels>1 mg/dL, right lobe donor hepatectomy, male donor, and abnormal liver biopsy findings were significant risk factors for postoperative hyperbilirubinemia (P=.015, P=.02, P<.01, P=.008, and P=.023 respectively). Also donor age>50 years showed a slight effect on hyperbilirubinemia (P=.052). Blood transfusions and surgical times were not significant factors. Donor safety is paramount, requiring thorough donor evaluation. Extensive liver resection may result in transient functional impairment. Several factors are believed to play roles in the development of postoperative hyperbilirubinemia after living-donor hepatectomy.
    No preview · Article · Mar 2011 · Transplantation Proceedings
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    ABSTRACT: Graft rejection is a serious problem despite immunosuppressive agents. Immunosuppression has been achieved with monoclonal antibodies (mAb) that bind specifically to the α subunit of the interleukin (IL)-2 receptor present on activated T lymphocytes. We explored the effects of two of the mAbs-daclizumab and basiliximab-on graft function. Our 1543 renal transplant recipients received baseline therapy with cyclosporine or tacrolimus plus corticosteroids and mycophenolate mofetil. In addition standard dosages intravenously of daclizumab (n=156) or basiliximab (n=45) in were administered intravenously to 201 renal transplant patients who included 122 men and 79 women of overall mean age of 30±13.7 years. Patient and donor characteristics including age, sex, causes of renal failure, presence of comorbidities, panel-reactive antibodies, and numbers of human leukocyte antigen-mismatched were similar between the groups. During a mean follow-up of 27±20 months, biopsy-proven acute rejection was observed in three patients in the basiliximab group and 23 in the daclizumab group. Cytomegalovirus infection occurred in 13 patients. There was no case of posttransplant lymphoproliferative disorder. Three polyoma BK nephropathies were detected in the daclizumab group. No hypersensitivity reaction occurred in either group. One-year patient survival was 100% in the basiliximab group and 99% in the daclizumab group, with graft survivals of 95% versus 94%, respectively. The mean creatinine levels at discharge were 2 mg/dL versus 2.3 mg/dL and at 12 months, 1.3 mg/dL versus 1.2 mg/dL, respectively. Acute rejection episodes remain a significant risk factor for the development of graft dysfunction and poor long-term graft survival. IL-2R antagonists were effective antibody therapies. There was no apparent difference between basiliximab and daclizumab treatment.
    No preview · Article · Mar 2011 · Transplantation Proceedings
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    ABSTRACT: Despite medical and surgical advances, vascular complications remain common after renal transplant, occurring among 3%-15% of patients. These complications may compromise graft function. This study sought to evaluate the frequency and management of vascular complications after renal transplant. We retrospectively analyzed the 1843 transplantations performed at 2 centers by our team since November 1975. The 1349 male and 494 female patients had an overall mean age of 31.5±11.2 years; (range, 3-66). Grafts were obtained from a living-related donor in 1406 (76.29%) or a deceased donor in the remaining 437 (23.71%). The mean donor age was 40.7±13.7 years (range, 2-76). Of 1843 transplants, multiple vascular anastomoses were performed in 155 cases (8.4%), including 130 involving renal arteries and 25 renal veins. Forty-seven vascular complications (2.55%) were observed in 43 procedures (2.33%), most frequently renal artery stenosis (n=14). It was followed by allograft renal artery kinking (n=7), renal vein kinking (n=7), renal artery thrombosis (n=5), renal vein laceration (n=4), renal artery laceration (n=3), renal vein thrombosis (n=2), renal artery disruption (n=2), renal and iliac vein obstructions owing to pressure from a lymphocele (n=1), renal artery and vein obstruction owing to pressure from a hematoma (n=1), or an arteriovenous fistula after percutaneous graft biopsy (n=1). Fifteen of these 47 complications were treated by interventional radiologic procedures. The vascular complication rates in our patients were somewhat lower than those reported in the literature. A thorough understanding of how complications impair allograft function and survival is essential for adequate treatment. Interventional radiology is invaluable in the postoperative management of transplant-related complications.
    No preview · Article · Mar 2011 · Transplantation Proceedings
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    ABSTRACT: Portal vein stenosis is a relatively rare complication after living-donor liver transplantation, which sometimes leads to a life-threatening event owing to gastrointestinal bleeding or graft failure. This study sought to evaluate the diagnoses and management of late-onset portal vein stenosis in pediatric living-donor liver transplants. Since September 2001, we performed 123 living-donor liver transplant procedures in 120 children, among which 109 children with a functioning graft at 6 months after living-donor liver transplant are included in this analysis. Seven instances of portal vein stenosis were diagnosed and were analyzed retrospectively. The median age of the children was 5.3 years, and the median body weight was 19.2 kg. Portal vein stenosis was diagnosed at 11.2±3.1 months after living-donor liver transplantation. Whereas 3 children were asymptomatic, splenomegaly and/or massive ascites were observed in the remaining 4. Additionally, platelet counts were below the normal limit in 4 children. All children were treated with transhepatic balloon dilatation except 1. Intraluminal stent placement was needed in 1 child owing to resistance of balloon dilatation. The mean pressure gradient decreased from 12.4 to 3.2 mmHg after successful treatment. We did not observe any treatment-related complications. Portal venous patency was maintained in all children during posttreatment follow-up of 43.2±20.4 months. There were no recurrences of portal vein stenosis. One child died; the remaining 6 children are alive with good graft function at 49.8±23.9 months of follow-up. Although most portal vein stenosis is asymptomatic, splenomegaly and platelet counts are 2 important markers for portal vein stenosis. Early detection of portal vein stenosis with these 2 markers can lead to successful interventional percutaneous approaches and avoid graft loss.
    No preview · Article · Mar 2011 · Transplantation Proceedings
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    ABSTRACT: Recurrence of hepatitis B virus after a liver transplantation (OLT) is a risk factor affecting graft and patient survivals. Short-term hepatitis B virus reactivation rates after OLT range between 3% and 15%. Using combination prophylaxis, the outcomes of OLT among patients with liver disease related to hepatitis B virus have improved to levels comparable to those whose disease is not related to hepatitis B virus. Since September 2001, we performed 288 OLT in 282 patients including 74 who had liver failure related to hepatitis B virus among whom 58 were followed for >12 months and analyzed retrospectively. Our protocol included lamivudine (100 mg orally per day beginning the day after surgery) and hepatitis B immunoglobulin (10,000 IU IV during the anhepatic phase, 2000 IU/d IV during the first week after surgery, 2000 IU IV/month from postoperative months 1 to 12). Using our protocol, the anti-hepatitis B surface antibodies (HBsAb) serum titer was maintained up to 100 IU/mL. The female:male ratio was 11:47. The mean age of patients was 43±12.8 years. Five patients died of causes unrelated to hepatitis B virus. At the time of death, their hepatitis B surface antigens were negative, and serum titers of anti-HBsAb were 45, 35.3, 56.4, 79.6, and 123 IU/mL. Mean follow-up was 46.5±18.9 months (range, 12-79). The hepatitis B surface antigen became positive in 4 patients; the remaining 49 had no evidence of hepatitis B surface antigen. In 18 patients, serum titer of anti-hepatitis B surface antigen was 0; in the remaining 31 patients, it was 69.2±133 IU/mL. Our combination protocol with hepatitis B immunoglobulin and lamivudine is a safe, cost-saving, and effective treatment for hepatitis B virus prophylaxis after liver transplantation.
    No preview · Article · Mar 2011 · Transplantation Proceedings
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    ABSTRACT: Multiple complications in liver transplant have been described in the literature. However, appendicitis and diaphragmatic hernia have rarely been reported after solid-organ transplant. The clinical presentation of appendicitis is similar to that of nontransplant patients, but complications are more frequent, because the majority of the patients do not have leukocytosis. Diaphragmatic hernia can present with a variety of atypical clinical symptoms. In this report, 1 patient who developed a diaphragmatic hernia and appendicitis after liver transplant is presented. A 2-year-old boy with end-stage liver cirrhosis owing to progressive familial intrahepatic cholestasis type-2 received a living-donor liver transplant. The posttransplant course was complicated. The diagnosis of diaphragmatic hernia was confirmed by thoracoabdominal computed tomography, and we decided to proceed with surgical repair. The patient had evidence of perforation, and the appendix was removed. After repositioning the intestine in the abdomen, a chest tube was placed, and the defect repaired with interrupted polypropylene sutures. The patient recovered after surgery without untoward sequelae.
    No preview · Article · Feb 2011

  • No preview · Article · Jul 2010 · Transplantation

  • No preview · Article · Jul 2010 · Transplantation

Publication Stats

63 Citations
47.43 Total Impact Points

Institutions

  • 2015
    • Medipol University
      • Faculty of Medicine
      İstanbul, Istanbul, Turkey
  • 2010-2013
    • Baskent University
      • • Faculty of Medicine
      • • Department of General Surgery
      Engüri, Ankara, Turkey
  • 2012
    • Baskent Üniversitesi Ankara Hastanesi
      Engüri, Ankara, Turkey