S. Aktas

Baskent University, Engüri, Ankara, Turkey

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Publications (22)45.8 Total impact

  • [Show abstract] [Hide abstract]
    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.
    Diagnostic molecular pathology: the American journal of surgical pathology, part B 11/2013; 22(4). DOI:10.1097/PDM.0b013e31828ed856
  • 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.
    10/2012; 2012:741754. DOI:10.1155/2012/741754
  • Turkish Journal of Surgery 01/2012; 28(1):34. DOI:10.5097/1300-0705.UCD.1401-12.01
  • Transplantation 01/2012; 94(10S):415. DOI:10.1097/00007890-201211271-00780
  • Transplantation 01/2012; 94(10S):414. DOI:10.1097/00007890-201211271-00777
  • Transplantation 01/2012; 94(10S):1208. DOI:10.1097/00007890-201211271-02398
  • Transplantation 01/2012; 94(10S):415. DOI:10.1097/00007890-201211271-00779
  • Transplantation 01/2012; 94(10S):73. DOI:10.1097/00007890-201211271-00133
  • Transplantation 01/2012; 94(10S):414. DOI:10.1097/00007890-201211271-00778
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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.
    Transplantation Proceedings 12/2011; 43(10):3807-12. DOI:10.1016/j.transproceed.2011.09.067
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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.
    06/2011; 9(3):187-90.
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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.
    Transplantation Proceedings 03/2011; 43(2):453-7. DOI:10.1016/j.transproceed.2011.01.075
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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.
    Transplantation Proceedings 03/2011; 43(2):427-30. DOI:10.1016/j.transproceed.2011.01.008
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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.
    Transplantation Proceedings 03/2011; 43(2):557-61. DOI:10.1016/j.transproceed.2011.01.007
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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.
    Transplantation Proceedings 03/2011; 43(2):601-4. DOI:10.1016/j.transproceed.2011.01.010
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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.
    Transplantation Proceedings 03/2011; 43(2):598-600. DOI:10.1016/j.transproceed.2011.01.006
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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.
    02/2011; 9(1):63-7.
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    ABSTRACT: Liver transplant is the definitive treatment for the end-stage liver disease. Although effective immunosuppressants are available, steroid-resistant acute rejection can be encountered. Between September 2001 and April 2010, 285 adult and pediatric liver transplants were done on 279 patients from deceased donors and living-related donors at our center. All patients received tacrolimus-based immunosuppressive therapy. Steroids were tapered in 3 months. Liver biopsy was done to confirm acute rejection after vascular or biliary complications had been excluded. High-dose steroids were administered for acute rejections. If there was no response to steroids, acute rejection was defined as steroid-resistant acute rejection. After confirming steroid-resistant acute rejection by a second biopsy, antithymocyte globulin was given to patients until liver functions return to normal level with ganciclovir prophylaxis. Acute rejection was detected in 87 liver transplants (30.5%). Steroid-resistant acute rejections were detected in 12 of 87 patients (7 male, 5 female; 8 pediatric, 4 adult patients; mean age, 16.08 +/- 12.1 years) (13.7%). Mean time from transplant to steroid-resistant acute rejection was 73.58 +/- 59.24 days (range, 20-181 days). The predominant cause of liver disease before liver transplant in patients who had steroid-resistant acute rejection was fulminant hepatic failure. Steroid-resistant acute rejection therapy was successful in 10 of 12 patients (83.3%). Two patients did not respond to therapy; therefore, they advanced to chronic rejection. Adverse effects due to cytokine release were the most frequently encountered reactions in the early period of antithymocyte globulin treatment. The mean follow-ups after steroid-resistant acute rejection treatment were 38.2 +/- 26 months (range, 2-85 months). We did not encounter any serious reaction, serious infection, or long-term adverse effect after antithymocyte globulin treatment. According to our experience, antithymocyte globulin can be considered as a good therapeutic option in steroid-resistant acute rejection with acceptable adverse effects.
    06/2010; 8(2):172-7.
  • Transplantation 01/2010; 90. DOI:10.1097/00007890-201007272-00153
  • Transplantation 01/2010; 90. DOI:10.1097/00007890-201007272-01597