ABAbdurrahman Mithat Bozdayi

Abdurrahman Mithat Bozdayi

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Previous Organizations / Institutes

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Abdurrahman Mithat Bozdayi has a total of 438 co-authors. Here are the top co-authors by number of shared publications:


Latest Publications

  • Two cases of COVID-19 reinfection in Turkey

    by İrEm Akdemir-Kalkan1, Nejat Siraj Mohammed, Güle Çınar, Ezgi Gülten, Elif Mukime Sarıcaoglu, Zeynep Ceren Kip-Karahan, Abdurrahman Mithat Bozday, Alpay Azap

    SARS-CoV-2 has affected the whole world while the number of cases is increasing rapidly. Several reinfection cases have been reported with the rise in the number of infected people. It is important to study these reinfection cases as the knowledge gained can be used in critical decisions (...)

  • Open Access

    ATA Index: A Novel Score for Predicting Fibrosis Stage in Chronic Viral Hepatitis

    by Handan Yarkan Tugsal, Selcen Yuksel, Gokhan Kabacam, Sami Evirgen, Kubra Akan, Filiz Akyuz, Mine Gulluoglu, Esra Erden, A. Mithat Bozdayi, Kubilay Cinar, et al.

    Background and Aim: This study was designed to predict the fibrosis stage with a clinical scoring system that may reduce the need for liver biopsy. Materials and Methods: The study cohort included the treatment of 430 chronic hepatitis B (CHB) and 170 chronic hepatitis C (CHC) of naive patients. The patients were divided into two groups as mild to moderate and severe fibrosis. After an index obtained in the study cohort, the index was tested in a validation cohort and compared with the FIB-4 Index. Results: The AUC of CHC index was found of 0.89 the sensitivity of 0.91 the specificity of 0.74, the positive predictive value (PPV) of 0.54 and the negative predictive value (NPV) of 0.96. The FIB-4 Index was applied to the CHC study cohort and the ATA Index Hepatitis C was found to be superior in terms of AUC (0.89–0.82), sensitivity (0.91–0.76) and NPV (0.96–0.86). The AUC of CHB Index was determined of 0.92, the sensitivity of 0.90, the specificity of 0.84, the PPV of 0.53 and the NPV of 0.98. Compared to the FIB-4 Index in CHB study cohort, the ATA Index Hepatitis B was predominant in terms of AUC (0.92–0.88), sensitivity (0.90–0.75), NPV (0.98–0.94) and PPV (0.53–0.49). Conclusion: ATA Indexes can predict the non-existence of severe fibrosis with an accuracy similar to FIB-4 Index and may reduce the need for liver biopsy.


  • Open Access

    The role of PNPLA3 (rs738409) c>g variant on histological progression of non-alcoholic fatty liver disease

    by Ramazan Idilman, Senem Ceren Karatayli, Gokhan Kabacam, Berna Savas, Atilla Halil Elhan, A Mithat Bozdayi

    Background and Aim: The present study aims to investigate the role of genetic variability of the PNPLA3 gene (adiponectin) in predisposition to non-alcoholic fatty liver disease (NAFLD) by comparing NAFLD patients to healthy controls and to investigate any impact of the PNPLA3 genetic variability on the natural course of the disease. Materials and Methods: This cohort consisted of 174 patients with biopsy-proven NAFLD and 151 healthy controls. DNA was extracted from peripheral blood and the rs738409 C>G single nucleotide polymorphism was assessed using PCR-DNA sequencing. Results: The frequency distribution of the GG genotype was significantly higher in NAFLD patients than in controls (p=0.01). In patients with NAFLD, the GG genotype was associated with lower platelet counts (p=0.001), the presence of steatohepatitis (p=0.04) and hepatic fibrosis (p=0.016). After adjustment for age, gender, obesity, and diabetes mellitus, the GG genotype was an independent predictor of significant hepatic fibrosis (adjusted odds ratio =3.031 p=0.012). From the baseline to sequential liver biopsies, the progression of NAS in NAFLD patients was slightly higher in the GG genotype than that of CC and GG genotypes (p=0.18). Conclusion: The PNPLA3 GG genotype is a predisposing factor for the development of hepatic steatosis in NAFLD patients and related to a more severe liver disease.


  • Evaluation of the results of MOTAKK hepatitis C virus RNA genotyping and hepatitis delta virus external quality assessment programs during 2015-2016

    by Ersin Karataylı, Ege Soydemir, Zeynep Büşra Aksoy, Mehtap Kızılpınar, Aylin Altay Koçak, Senem Ceren Karataylı, Esra Yurdcu, Umut Yıldırım, Haluk Güriz, Gülendam Bozdayi, et al.

    Background/Aims: To evaluate the HCV RNA genotyping and HDV RNA tests that are performed in molecular microbiology laboratories in Turkey as part of a national external quality assessment programme, MOTAKK (Moleküler Tanıda Kalite Kontrol) (English translation: Quality control in molecular diagnostics). Materials and Methods: Plasmas having different HCV RNA genotypes were used to prepare HCV genotype control sera. The HDV RNA main stock was prepared from patients with chronic delta hepatitis who had a significant amount of viral load detected, as per the WHO reference materials on viral load studies that were compiled for the purpose of developing HDV RNA control sera. Samples with different viral loads were prepared from this main stock by dilution. The prepared controls were delivered to the registered laboratories. The laboratories carried out the relevant tests and entered their results via the MOTAKK web page. External quality assessment (EQA) reports of the participants were uploaded to the website as well. Results: In total, there were 23 participating laboratories, out of which 20 exclusively performed HCV genotyping, and 15 and 16 only performed HDV RNA in 2015 and 2016, respectively. The success rate of the results of the HCV genotype was 56-96% in 2015 and 30-95% in 2016. The tube with a 30% success rate had a recombinant type of HCV, therefore, it could not be detected in most of the laboratories. The HDV RNA results were evaluated qualitatively. Accordingly, HDV RNA detection rates of participant laboratories were 71-100% in 2015 and 50-100% in 2016. Conclusion: This study was the first national external quality control program in Turkey regarding HCV RNA genotyping and HDV RNA in the field of molecular microbiology, and it was implemented successfully.

  • Epidemiology of blood-borne viral infections in Afghanistan

    by Abbas Ali Husseini, Khwaja Mir Islam Saeed, Esra Yurdcu, Rüçhan Sertoz, A. Mithat Bozdayi

    Although a few studies have been done on transmissible blood-borne viral infections in high-risk groups, little attention has been given to assessing the infection status of the general population in Afghanistan. To investigate the epidemiological status in the general population, we tested the serological markers of hepatitis B virus (HBV), hepatitis C virus (HCV), hepatitis delta virus (HDV), human immunodeficiency virus 1 (HIV-1) and human T-cell leukemia virus (HTLV) infections. In total, 492 samples were selected randomly from Nangarhar, Herat, Mazar-e Sharif, Kandahar, and Kabul from subjects between 25 and 70 years old. The samples were tested for the presence of HBsAg, anti-HBs, anti-HBc, anti-HDV, anti-HCV, anti-HIV-1 and anti-HTLV I/II antibodies using chemiluminescent immunoassays on Abbott Architect automated platforms. In addition, 220 HBsAg-positive samples identified among 5897 samples from the general population of the same regions of Afghanistan were included in the study and tested for both HBsAg and anti-HDV to investigate HDV prevalence in the country. Viral loads of HBV, HCV and HDV were determined in all seropositive samples using Ampliprep/Cobas TaqMan HBV, HCV, Test Roche (CA, USA), and an in-house method, respectively. Out of 492 samples, 31 (6.3%), 136 (27.6%) and 149 (30.3%) were found to be positive for HBsAg, anti-HBs and anti-HBc, respectively. Anti-HDV positivity was detected in five (2.1%) out of 234 HBsAg-positive samples (including 14 of the randomly selected samples that were not among the 220 previously identified as HBsAg positive). Only eight out of 492 (1.6%) subjects were positive for anti-HCV antibodies. Seven out of 489 (1.4%) were positive for anti-HIV-1 antibodies, and three out of 466 cases (0.6%) were positive for anti-HTLV I/II antibodies. These results suggest that Afghanistan is an intermediate endemic region for HBV, HDV and HCV infection. The prevalence of HIV-1 seems to be significantly higher than the global prevalence and that of the eastern Mediterranean region. In addition, the HTLV I/II screening results suggest that these viruses should be monitored in Afghanistan to confirm the trend observed in the current study.


  • Evaluation of 2015-2016 MOTAKK HBV DNA and HCV RNA External Quality Assessment National Program Results

    by Ersin Karatayli, Ege Soydemi̇r, Zeynep Büşra Aksoy, Mehtap Kizilpinar, Aylin Altay Koçak, Senem Ceren Karatayli, Esra Yurdcu, Umut Yildirim, Haluk Güri̇z, Gülendam Bozdayi, et al.

    MOTAKK, as a national external quality control program has been launched to evaluate the molecular detection of viral infections including HBV DNA and HCV RNA in molecular microbiology diagnostic laboratories in Turkey. This program is prepared in compliance with ISO 17043:2010 (Conformity assessment general requirements for proficiency testing) standards, and aims to take the place of external quality control programs from abroad, contributing to standardization and accuracy of molecular diagnostic tests in our country. The aim of this study was to evaluate 2015 and 2016 results of the MOTAKK External Quality Control Program for HBV DNA and HCV RNA viral load. The calls were announced on the web page of MOTAKK (www.motakk.org). The quality control samples were sent to participating laboratories in 2015 and 2016. Main stocks were prepared from patients with chronic hepatitis B and C who had viral load detection with reference methods according to WHO reference materials for viral load studies to improve quality control sera. From these main stocks, samples with different viral loads were prepared from dilutions of plasma with HBV, HCV, HAV, HIV, Parvovirus B19 and CMV negative serologic markers. Quality control samples were sent to the participating laboratories along with the negative samples in the cold chain. The laboratories accomplished the related tests within 2-3 weeks and entered their results on the MOTAKK web page. These results were analysed according to ISO 13528 (Statistical methods for use in proficiency testing by interlaboratory comparison) and scoring reports were created by a software developed by MOTAKK and sent to participating labs. Each laboratory evaluated their own results in comparison with the other laboratory results, reassessed the tests via observing the distance from the mean result and the reference values. The number of laboratories participating in the HBV DNA and HCV RNA external quality control program was 70-73 in 2015-2016. Participants were able to comply with the program tools, registering, entering results and receiving the results reports problem. In HBV panel, 72.6-89.1% and 84.7-90.3% of the participant laboratories were in 1 standard deviation (SD) in 2015-2016, respectively. In HCV panel, 70.8-89.1% and 84.7-90.3% of the participant laboratories were in 1 SD in 2015-2016, respectively. A national external quality control program for HBV DNA and HCV RNA in Turkey has been prepared for the first time with this project and implemented successfully. All the data provided in the MOTAKK external quality control program final report, compensate all the data provided by the quality control program final reports from abroad; additionally, the report allows comparison of used technologies and commercial products.

  • Optimizing lonafarnib treatment for the management of chronic delta hepatitis: The LOWR HDV‐1 study

    by Cihan Yurdaydin, Onur Keskin, Çağdaş Kalkan, Fatih Karakaya, Aysun Çalişkan, Ersin Karatayli, Senem Karatayli, A. Mithat Bozdayi, Christopher Koh, Theo Heller, et al.

    In a proof‐of‐concept (POC) study, the oral prenylation inhibitor, lonafarnib (LNF), decreased hepatitis D virus (HDV) RNA during 4 weeks of treatment. Here, we explored optimal LNF regimens. Fifteen patients (five groups; 3 per group) completed dosing as follows: (1) LNF 200 mg twice‐daily (BID; 12 weeks); (2) LNF 300 mg BID (12 weeks); (3) LNF 100 mg thrice‐daily (5 weeks); (4) LNF 100 mg BID + pegylated interferon alfa (PEG‐IFNα) 180 μg once‐weekly (QW; 8 weeks); and (5) LNF 100 mg BID + ritonavir (RTV) 100 mg once‐daily (QD; 8 weeks). Tolerability and efficacy were assessed. Higher LNF monotherapy doses had greater decreases in HDV viral load than achieved in the original POC study. However, this was associated with increased gastrointestinal adverse events. Addition of RTV 100 mg QD to a LNF 100 mg BID regimen yielded better antiviral responses than LNF 300 mg BID monotherapy and with less side effects. A similar improvement was observed with LNF 100 mg BID + PEG‐IFNα 180 μg QW. Two of 6 patients who received 12 weeks of LNF experienced transient posttreatment alanine aminotransferase (ALT) increases resulting in HDV‐RNA negativity and ALT normalization. Conclusion : The cytochrome P450 3A4 inhibitor, RTV, allows a lower LNF dose to be used while achieving higher levels of postabsorption LNF, yielding better antiviral responses and tolerability. In addition, combining LNF with PEG‐IFNα achieved more substantial and rapid HDV‐RNA reduction, compared to historical responses with PEG‐IFNα alone. Twelve weeks of LNF can result in posttreatment HDV‐RNA negativity in some patients, which we speculate results from restoring favorable immune responses. These results support further development of LNF with RTV boosting and exploration of the combination of LNF with PEG‐IFN. (H epatology 2018;67:1224‐1236)


  • Discontinuation of Lamivudine Treatment in HBeAg-Negative Chronic Hepatitis B: A Pilot Study with Long-Term follow-up

    by Fatih Karakaya, Sevil Özer, Çağdaş Kalkan, E Ali Tüzün, Aysun Çalişkan, Onur Keskin, Gökhan Kabaçam, Senem Karatayli, Ersin Karatayli, A Mithat Bozdayi, et al.

    Background: Finite treatment of hepatitis B e antigen (HBeAg)-negative chronic hepatitis B (CHB) with nucleoside/nucleotide analogues (NAs) is important in resource-limited countries. Outcome of treatment discontinuation in patients on long-term lamivudine (LVD) was assessed in a single centre observational pilot study in the current study. Methods: Non-cirrhotic patients on LVD for at least 5 years with undetectable HBV DNA on at least two consecutive assessments were offered to stop treatment. Biochemical, serological and virological measures were determined at 3–6 month intervals after treatment discontinuation. Serum quantitative hepatitis B surface antigen (HBsAg) was determined at treatment discontinuation and 5–6 years thereafter. NA treatment was re-instituted in patients with confirmed viral rebound defined as HBV DNA >20,000 IU/ml. Relapser patients were no longer followed but were re-assessed 6 years after treatment cessation. Results: LVD was discontinued in 23 patients. 8 patients relapsed within 1 year and NA treatment was restarted; 15 patients (65%) were non-relapsers. Thirteen of them were followed for at least 5 years. Two patients had undetectable HBV DNA throughout the follow-up period. In the rest, HBV DNA fluctuated at low levels. Two patients cleared HBsAg 24 and 36 months after stopping treatment. Quantitative HBsAg levels 5–7 years after treatment discontinuation were lower in non-relapser compared to relapser patients (1.21 IU/ml ±0.98 versus 2.71 ±0.76; P=0.002). Of 8 relapser patients 1 patient had HBsAg levels less than 100 IU/ml compared to 11 out of 13 non-relapser patients ( P=0.0022). Conclusions: These data suggest that cessation of NA treatment is a viable option after a reasonable treatment duration in patients with HBeAg-negative CHB and that HBsAg clearance may become an achievable target in these patients.


  • O118 : Optimizing the prenylation inhibitor lonafarnib using ritonavir boosting in patients with chronic delta hepatitis

    by C. Yurdaydin, R. Idilman, I. Choong, C. Kalkan, O. Keskin, M.F. Karakaya, A.E. Tuzun, E. Karatayli, M. Bozdayi, D. Cory, et al.


  • Investigation of West Nile virus among healthy blood donors in the western part of Turkey

    by Servet Uluer Biçeroğlu, Ersin Karatayli, Arzu Bayram, Ajda Turhan, Aysu Değirmenci, Yeşim AYDINOK, Abdurrahman Mithat Bozdayi, Şaziye Rüçhan Sertöz

    Background/aim: The West Nile virus (WNV) is a mosquito-borne flavivirus causing different forms of infection among humans, varying from asymptomatic illness to fetal central nervous system infection. Turkey lies within an endemic region for WNV. Transfusion of infected blood products is another well-documented major route of transmission. The aim of our study was to investigate the presence of WNV viremia among a healthy donor population from the western part of the country. Materials and methods: A total of 438 healthy volunteer blood donors were included in the study. The presence of WNV RNA was investigated by quantitative real-time reverse-transcriptase polymerase chain reaction (qRT-PCR) and anti-WNV IgG was detected by a commercial ELISA test. Results: Ages of volunteer donors were 18-62 years (mean: 34.7) and 34 (7.76%) were women. All samples were negative for WNV RNA by qRT-PCR. Eleven (2.51%) samples, 1 of which was borderline, were positive for anti-WNV IgG. All positive samples were from the western part of the country and 9 of them were from Izmir. Conclusion: Although all donor samples were negative for WNV RNA by qRT-PCR, the risk of WNV transmission via blood products should not be ignored in endemic regions.