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Featured researches published by Derya Onel.


Journal of Hepatology | 2003

Occult HBV infection and YMDD variants in hemodialysis patients with chronic HCV infection.

Fatih Besisik; Cetin Karaca; Filiz Akyuz; Sibel Horosanlı; Derya Onel; Selim Badur; Mehmet Şükrü Sever; Ahmet Danalioglu; Kadir Demir; Sabahattin Kaymakoglu; Yilmaz Cakaloglu; Atilla Ökten

BACKGROUND/AIMS End-stage renal disease patients on chronic hemodialysis are at risk for both hepatitis B virus (HBV) and hepatitis C virus (HCV) infection. Although the prevalence is unknown in hemodialysis patients, occult HBV infection is frequent in subjects with chronic HCV infection. We aimed to investigate (1) the prevalence and clinical impact of occult HBV infection in hemodialysis patients with chronic HCV infection, and (2) the frequency of YMDD variants (tyrosine-methionine-aspartate-aspartate amino acid motif of HBV polymerase) in this setting. METHODS Thirty-three anti-HCV and HCV-RNA-positive, HBsAg-negative hemodialysis patients (mean age 36.9+/-10.4 years, 22 male) were admitted to this study. HBV-DNA (Innogenetics kit) and HCV-RNA (Cobas Amplicor HCV kit) were investigated by polymerase chain reaction technique (PCR). YMDD mutation was studied in all HBV-DNA-positive patients by the BOOM method. RESULTS HBV-DNA was detected in 12 of 33 patients (36.4%) by PCR. Their mean age was 33.0+/-9.0 years. Age, dialysis period (years) and biochemical parameters were not significantly different in patients with and without occult HBV infection. YMDD variants were identified in six of 12 (50%) patients with occult HBV infection. CONCLUSIONS Occult HBV infection is frequent in hemodialysis patients with chronic HCV infection. YMDD variants are common in this setting.


Antimicrobial Agents and Chemotherapy | 2013

Efficacy of Tenofovir in Patients with Lamivudine Failure Is Not Different from That in Nucleoside/Nucleotide Analogue-Naïve Patients with Chronic Hepatitis B

Bulent Baran; Ozlem Mutluay Soyer; Asli Ormeci; Suut Gokturk; Sami Evirgen; Hamza Ugur Bozbey; Filiz Akyuz; Cetin Karaca; Kadir Demir; Fatih Besisik; Derya Onel; Mine Gulluoglu; Selim Badur; Sabahattin Kaymakoglu

ABSTRACT We evaluated the efficacy of tenofovir disoproxil fumarate (TDF) in patients with lamivudine failure (LAM-F) in comparison with that in nucleoside/nucleotide analogue (NA)-naïve patients with chronic hepatitis B (CHB). The criteria for inclusion were being NA naïve or having previous LAM-F and receiving TDF therapy for at least 6 months. Biochemical and virological tests were performed at the baseline, at 3-month intervals in the first year, and every 6 months thereafter. The primary outcome measure for efficacy was a complete virological response (CVR), defined as an HBV DNA level of <20 IU/ml. CVR rates were calculated by Kaplan-Meier analysis, and a multivariate Cox proportional-hazard model was generated in order to find predictive factors independently associated with the time to a CVR. We included 197 patients in the study (136 males; mean age, 43 ± 12 years; 105 patients were NA naïve). Sixty-five patients had hepatitis B e antigen (HBeAg)-positive CHB. The median duration of TDF treatment was 29 (range, 6 to 52) months. Seventy-one patients (77%) in the LAM-F group were treated with TDF add-on therapy. The CVR rates of the NA-naïve and LAM-F groups were comparable in HBeAg-negative (94% versus 96% at month 36, P = 0.10) and HBeAg-positive patients (67% versus 83% at month 36, P = 0.48). According to the multivariate Cox regression model, only HBeAg positivity (hazard ratio [HR], 0.39; 95% confidence interval [CI], 0.26 to 0.59; P < 0.001) and a high baseline HBV DNA level (HR, 0.44; 95% CI, 0.29 to 0.67; P < 0.001) had a significant influence on the time to a CVR. The similar cumulative CVR rates during the follow-up show that TDF has comparable efficacy in lamivudine-experienced and NA-naïve patients, and the presence of resistance mutations did not alter the response rates.


Journal of Medical Virology | 2008

Acute hepatitis A virus infection in Turkey.

Andrea Normann; Selim Badur; Derya Onel; Ayse Kilic; Müjgan Sıdal; Bernard Larouze; Véronique Massari; Julia Müller; Bertram Flehmig

Anti‐HAV IgM positive serum samples from acute phase hepatitis A patients from various areas in Turkey were tested for viral RNA by RT‐PCR (reverse transcriptase polymerase chain reaction), using primer pairs from two different regions of the HAV genome. The PCR products amplified from both genomic regions underwent phylogenetic analyses. A comparison of the regions showed the same genotyping results, and the RT‐PCR‐2 in the 5′NCR demonstrated greater sensitivity compared to RT‐PCR‐1 in the VP1‐P2A region. The majority of the isolates belonged to genotype IB and are related closely to each other; however, two isolates related even more strongly to the HAV HM175 strain. Two (n = 37) RT‐PCR positive sera were classified under genotype IA. A surprising finding emerged for the mean levels of serum transaminases AST and ALT: higher levels were found in patients under 10 years of age compared to older patients. Anti‐HAV IgM levels were determined quantitatively and, in addition, the HAV‐RNA genome equivalents were ascertained by real time RT‐PCR. No evidence was found for an association between viral load and the higher transaminase levels in the younger group. J. Med. Virol. 80:785–790, 2008.


Liver International | 2009

Prevalence and virological features of occult hepatitis B virus infection in female sex workers who work uncontrolled in Turkey.

Binnur Pinarbasi; Derya Onel; Fulya Cosan; Filiz Akyuz; Nezihe Dirlik; Yilmaz Cakaloglu; Selim Badur; Fatih Besisik; Kadir Demir; Atilla Ökten; Sabahattin Kaymakoglu

Background: There is little information about the prevalence of occult hepatitis B virus infection (OHBVI). We have investigated the prevalence and virological features of OHBVI among female sex workers (FSWs) in Istanbul.


Clinical Gastroenterology and Hepatology | 2014

Effects of Polymorphisms in Interferon λ 3 (Interleukin 28B) on Sustained Virologic Response to Therapy in Patients With Chronic Hepatitis D Virus Infection

Emre Yilmaz; Bulent Baran; Ozlem Mutluay Soyer; Mustafa Onel; Derya Onel; Asli Ormeci; Suut Gokturk; Sami Evirgen; Filiz Akyuz; Kadir Demir; Fatih Besisik; Sabahattin Kaymakoglu; Cetin Karaca

BACKGROUND & AIMS We investigated the association between interferon λ 3 (IFNL3) genotype (also known as interleukin 28B) and response to IFNα therapy in patients with chronic hepatitis D virus (HDV) infection. METHODS We studied IFNL3 genotypes of 32 patients (19 men; median age, 42.5 y) with chronic HDV infection. Nineteen patients (59%) were treated with pegylated IFNα and 13 patients (41%) were treated with standard IFNα, for at least 12 months. Levels of HDV RNA were measured before the initiation of treatment and every 6 months thereafter; patients were followed up for a median time of 16 months (range, 6-164 mo) after treatment ended. We used real-time polymerase chain reaction to classify the IFNL3 polymorphism rs12979860 as CC, CT, or TT, and rs8099917 as TT, GT, or GG. A virologic response was defined as undetectable HDV RNA in serum, and a sustained virologic response (SVR) was defined as undetectable HDV RNA after cessation of treatment until the end of the follow-up period. We evaluated the association between IFNL3 polymorphism and treatment response using univariate and multivariate analyses. RESULTS After treatment, a response was achieved in 16 patients (50%) and an SVR was achieved in 9 (28%). The percentages of patients with CC, CT, and TT at rs12979860 were 47%, 47%, and 6%, respectively; the percentages of patients with TT, GT, and GG at rs8099917 were 69%, 28%, and 3%, respectively. Rates of SVR were 27%, 27%, and 50% in patients with CC, CT, TT at rs12979860 (P = .78 for CC vs CT vs TT) and 36%, 11%, and 0% in patients with TT, GT, and GG at rs8099917 (P = .30 for TT vs GT vs GG). CONCLUSIONS The IFNL3 polymorphisms rs12979860 and rs8099917 do not significantly affect responses of patients with chronic HDV infection to treatment with IFNα.


Journal of General Virology | 2013

Role of the line probe assay INNO-LiPA HBV DR and ultradeep pyrosequencing in detecting resistance mutations to nucleoside/nucleotide analogues in viral samples isolated from chronic hepatitis B patients.

Sevim Meşe; Muzaffer Arikan; Aris Cakiris; Neslihan Abaci; Ergun Gumus; Olcay Kursun; Derya Onel; Duran Ustek; Sabahattin Kaymakoglu; Selim Badur; Osman Sadi Yenen; Emel Bozkaya

Despite the effectiveness of nucleoside/nucleotide analogues in the treatment of chronic hepatitis B (CHB), their long-term administration is associated with the emergence of resistant hepatitis B virus (HBV) mutants. In this study, mutations resulting in antiviral resistance in HBV DNA samples isolated from 23 CHB patients (nine treatment naïve and 14 treated previously) were studied using a line probe assay (INNO-LiPA HBV DR; Innogenetics) and ultradeep pyrosequencing (UDPS) methods. Whilst the INNO-LiPA HBV DR showed no resistance mutations in HBV DNA samples from treatment-naive patients, mutations mediating lamivudine resistance were detected in three samples by UDPS. Among patients who were treated previously, 19 mutations were detected in eight samples using the INNO-LiPA HBV DR and 29 mutations were detected in 12 samples using UDPS. All mutations detected by the INNO-LiPA HBV DR were also detected by UDPS. There were no mutations that could be detected by INNO-LiPA HBV DR but not by UDPS. A total of ten mutations were detected by UDPS but not by INNO-LiPA HBV DR, and the mean frequency of these mutations was 14.7 %. It was concluded that, although INNO-LiPA HBV DR is a sensitive and practical method commonly used for the detection of resistance mutations in HBV infection, UDPS may significantly increase the detection rate of genotypic resistance in HBV at an early stage.


International Journal of Infectious Diseases | 2016

Predictors of treatment requirement in HBeAg-negative chronic hepatitis B patients with persistently normal alanine aminotransferase and high serum HBV DNA levels.

Asli Ormeci; Yucel Aydin; Abdullah Sumnu; Bulent Baran; Ozlem Mutluay Soyer; Binnur Pinarbasi; Suut Gokturk; Mine Gulluoglu; Derya Onel; Selim Badur; Filiz Akyuz; Cetin Karaca; Kadir Demir; Fatih Besisik; Sabahattin Kaymakoglu

OBJECTIVES Serum alanine aminotransferase (ALT) is a controversial marker for disease monitoring in hepatitis B e antigen (HBeAg)-negative chronic hepatitis B (CHB) patients. The aim of this study was to determine the fibrosis stage and histological activity index (HAI) in HBeAg-negative CHB patients with persistently normal ALT (PNALT) and high serum HBV DNA (≥2000 IU/ml) and to investigate clinical risk factors for the requirement of treatment through the examination of liver biopsy specimens. METHODS HBeAg-negative CHB patients with PNALT (≤40 IU/l) and high serum HBV DNA (≥2000 IU/ml) were included. HBV fibrosis stage and HAI were scored according to the Ishak system. Multivariate logistic regression analysis was used to estimate the independent risk factors for fibrosis stage ≥2 and/or HAI ≥6. Receiver operating characteristic curve analysis was used to determine an optimal age cut-off for liver biopsy. RESULTS A total 120 patients were enrolled. These patients had a mean HBV DNA level of 123680±494500 IU/ml; the HBV DNA load was 2000-20000 IU/ml in 68 patients (56.6%) and ≥20000 IU/ml in 52 (43.4%). Eighteen patients (15%) had moderate-to-severe histological activity (HAI ≥6). Forty-three patients (35.9%) had a fibrosis stage ≥2. Forty-eight patients (40%) had a fibrosis stage ≥2 and/or HAI ≥6. On multivariate logistic regression analysis, independent variables associated with fibrosis stage ≥2 and/or HAI ≥6 included age and HBV DNA viral load. Patients with HBV DNA 2000-20000 IU/ml were more likely to require treatment compared to those with a viral load ≥20000 IU/ml. The optimal age cut-off to predict fibrosis stage ≥2 and/or HAI ≥6 was 46 years. CONCLUSIONS Significant liver damage was detected in 40% of CHB patients with PNALT and high HBV DNA upon biopsy. Age and HBV DNA viral load were independent predictors of significant liver damage. A biopsy to determine the degree of liver damage is advisable for CHB patients older than 46 years.


Postgraduate Medicine | 2016

Comparison of the efficacy of 12 months and longer courses of interferon therapy for the treatment of chronic delta hepatitis: a retrospective cohort study

Ozlem Mutluay Soyer; Bulent Baran; Aslı Ciftcibasi Ormeci; Suut Gokturk; Esra Aydın; Derya Onel; Mine Gulluoglu; Cetin Karaca; Filiz Akyuz; Kadir Demir; Fatih Besisik; Sabahattin Kaymakoglu

ABSTRACT Objectives: Interferon (IFN) therapy is associated with low rates of treatment success and high rates of recurrence in hepatitis D virus (HDV) infection. Several strategies to increase efficacy, including extending the treatment duration, have been tested. This study aimed to compare treatment outcomes between patients receiving 12 months vs. longer courses of interferon therapy for chronic delta hepatitis (CDH). Methods: Data from CDH patients receiving standard or pegylated IFN therapy were retrospectively evaluated. Patients were divided into two groups: group I received ≤12 months of therapy and group II received >12 months (maximum: 24 months) of therapy. Viral response at the end of treatment (EOT-VR), post-treatment week 24 viral response (PTW24- VR) and viral response after long-term follow-up (LTFU-VR) were compared. Parameters affecting virologic response were investigated. Results: Sixty-five patients, 14 in group I and 51 in group II, were included. The EOT-VRs were 21% and 45% (p > 0.05), and the PTW24-VRs were 7% and 41% (p = 0.02), respectively. Recurrence rates were 66% and 17% in Groups I and II, respectively. The LTFU-VRs were 7% and 37%, respectively (p = 0.04). The HDV RNA at week 24 of treatment was the only parameter significantly affecting the PTW24-VR (odds ratio: 71.2; 95% CI: 3.7–1353, p = 0.005). PTW24-VR was achieved in 68% and 5% of patients with negative and positive HDV RNA, respectively, at week 24 of treatment (p < 0.01). Conclusion: IFN treatment for up to 24 months may increase the virologic response rate for CDH. HDV RNA negativity at week 24 of treatment was a significant predictor of virologic response.


Emerging Infectious Diseases | 2008

Mutations in influenza A virus (H5N1) and possible limited spread, Turkey, 2006.

Ender Altiok; Fulya Taylan; Osman Ş. Yenen; Gülşah Demirkeser; Mürvet Bozaci; Derya Onel; Birsen Akcadag; A. Selma Iyisan; Meral Ciblak; Emel Bozkaya; Sirin Yuksel; Selim Badur

We report mutations in influenza A virus (H5N1) strains associated with 2 outbreaks in Turkey. Four novel amino acid changes (Q447L, N556K, and R46K in RNA polymerase and S133A in hemagglutinin) were detected in virus isolates from 2 siblings who died.


Liver International | 2015

Tenofovir disoproxil fumarate has a substantial efficacy against multidrug-resistant strains of hepatitis B virus.

Bulent Baran; Ozlem Mutluay Soyer; Asli Ormeci; Suut Gokturk; Sami Evirgen; Filiz Akyuz; Cetin Karaca; Kadir Demir; Fatih Besisik; Derya Onel; Mine Gulluoglu; Selim Badur; Sabahattin Kaymakoglu

To evaluate the efficacy of tenofovir in chronic hepatitis B (CHB) patients with adefovir resistance (ADF‐R) and suboptimal response to adefovir (ADF‐S).

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