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Dive into the research topics where Mehmet Akif Öztürk is active.

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Featured researches published by Mehmet Akif Öztürk.


American Journal of Human Genetics | 2013

Identification of multiple genetic susceptibility loci in Takayasu arteritis

Güher Saruhan-Direskeneli; Travis Hughes; Kenan Aksu; Gokhan Keser; Patrick Coit; Sibel Zehra Aydin; Fatma Alibaz-Oner; Sevil Kamali; Murat Inanc; Simon Carette; Gary S. Hoffman; Servet Akar; Fatos Onen; Nurullah Akkoc; Nader Khalidi; Curry L. Koening; Omer Karadag; Sedat Kiraz; Carol A. Langford; Carol A. McAlear; Zeynep Ozbalkan; Aşkın Ateş; Yasar Karaaslan; Kathleen Maksimowicz-McKinnon; Paul A. Monach; Huseyin T. E. Ozer; Emire Seyahi; Izzet Fresko; Ayse Cefle; Philip Seo

Takayasu arteritis is a rare inflammatory disease of large arteries. The etiology of Takayasu arteritis remains poorly understood, but genetic contribution to the disease pathogenesis is supported by the genetic association with HLA-B*52. We genotyped ~200,000 genetic variants in two ethnically divergent Takayasu arteritis cohorts from Turkey and North America by using a custom-designed genotyping platform (Immunochip). Additional genetic variants and the classical HLA alleles were imputed and analyzed. We identified and confirmed two independent susceptibility loci within the HLA region (r(2) < 0.2): HLA-B/MICA (rs12524487, OR = 3.29, p = 5.57 × 10(-16)) and HLA-DQB1/HLA-DRB1 (rs113452171, OR = 2.34, p = 3.74 × 10(-9); and rs189754752, OR = 2.47, p = 4.22 × 10(-9)). In addition, we identified and confirmed a genetic association between Takayasu arteritis and the FCGR2A/FCGR3A locus on chromosome 1 (rs10919543, OR = 1.81, p = 5.89 × 10(-12)). The risk allele in this locus results in increased mRNA expression of FCGR2A. We also established the genetic association between IL12B and Takayasu arteritis (rs56167332, OR = 1.54, p = 2.18 × 10(-8)).


Annals of the Rheumatic Diseases | 2003

Effects of interferon α treatment on the clinical course of refractory Behçet’s disease: an open study

Meral Calguneri; Mehmet Akif Öztürk; I. Ertenli; Sedat Kiraz; Sule Apras; Z. Ozbalkan

Interferon α (IFNα) has recently been introduced in the treatment of uveitis, mucocutaneous lesions, and arthritis of Behcet’s disease (BD).1–6 To our knowledge, there is currently no clinical trial which has evaluated the efficacy of IFNα treatment in the vascular or neurological involvement in BD. In this open study we evaluated the efficacy, toxicity, and tolerability of IFNα in the management of BD with ocular, articular, vascular, or neurological manifestations which had previously been unsuccessfully treated conventionally. A total of 29 patients (17 men, 12 women; mean age 33.2 months, range 16–51) who were resistant to conventional treatments were treated with systemic IFNα. Previous conventional treatments had been colchicine, aspirin, and penicillin plus sulfasalazine for patients with arthritis; or colchicine, aspirin, and penicillin plus steroids and/or immunosuppressive agents, azathioprine, cyclosporin A, or cyclophosphamide for ocular, vascular, and/or neurological involvement. The mean duration of the disease was 8.86 years (range 1–30). Four patients were excluded from the statistical analysis because of the short duration of treatment (<4 months). Seventeen patients had ocular inflammation. Eleven patients had arthritis. Ten patients had vascular disease (aneurisms in the internal cerebral and ophthalmic arteries; thrombosis of popliteal veins and left anterior descending coronary artery causing myocardial infarction; organised thrombus in superior and inferior caval, …


Arthritis Research & Therapy | 2012

Takayasu's arteritis is associated with HLA-B*52, but not with HLA-B*51, in Turkey

Ziver Sahin; Muge Bicakcigil; Kenan Aksu; Sevil Kamali; Servet Akar; Fatos Onen; Omer Karadag; Zeynep Ozbalkan; Aşkın Ateş; Huseyin T. E. Ozer; Vuslat Yilmaz; Emire Seyahi; Mehmet Akif Öztürk; Ayse Cefle; Veli Cobankara; A. Mesut Onat; Ercan Tunc; Nurşen Düzgün; Sibel Zehra Aydin; Neslihan Yilmaz; Izzet Fresko; Yasar Karaaslan; Sedat Kiraz; Nurullah Akkoc; Murat Inanc; Gokhan Keser; F. Aytül Uyar; Güher Saruhan-Direskeneli

IntroductionHLA-B*51 and HLA-B*52 are two close human leukocyte antigen (HLA) allele groups with minor amino acid differences. However, they are associated with two different vasculitides (HLA-B*51 in Behçets disease and HLA-B*52 in Takayasus arteritis (TAK)) and with major clinical and immunological differences. In this study, we aimed to screen a large cohort of TAK patients from Turkey for the presence of HLA-B*51 and HLA-B*52 as susceptibility and severity factors.MethodsTAK patients (n = 330) followed at a total of 15 centers were included in the study. The mean age of the patients was 37.8 years, and 86% were women. DNA samples from the patients and healthy controls (HC; n = 210) were isolated, and the presence of HLA-B*51 or HLA-B*52 was screened for by using PCR with sequence-specific primers.ResultsWe found a significant association of HLA-B*52 with TAK (20.9% vs HC = 6.7%, P = 0.000, OR = 3.7, 95% CI = 2.02 to 6.77). The distribution of HLA-B*51 did not differ between TAK patients and HCs (22.7% vs 24.8%, OR = 0.9, 95% CI = 0.60 to 1.34). The presence of HLA-B*52 decreased in late-onset patients (> 40 years of age; 12.0%, P = 0.024, OR = 0.43, 95% CI = 0.20 to 0.91). Patients with angiographic type I disease with limited aortic involvement also had a lower presence of HLA-B*52 compared to those with all other disease subtypes (13.1% vs 26%, P = 0.005, OR = 0.43, 95% CI = 0.23 to 0.78).ConclusionsIn this study, the previously reported association of TAK with HLA-B*52 in other populations was confirmed in patients from Turkey. The functional relevance of HLA-B*52 in TAK pathogenesis needs to be explored further.


Journal of Clinical Laboratory Analysis | 2016

The Association Between Neutrophil/Lymphocyte Ratio and Disease Activity in Rheumatoid Arthritis and Ankylosing Spondylitis

R. Mercan; Berivan Bitik; Abdurrahman Tufan; Utku Burak Bozbulut; Nuh Atas; Mehmet Akif Öztürk; Seminur Haznedaroglu; Berna Goker

Elevated neutrophil count is associated with poor prognosis and increased mortality in many conditions. Neutrophil to lymphocyte ratio (NLR) has emerged as a marker of inflammation in neoplastic and cardiovascular disorders. Herein, we investigated utility of this simple tool in rheumatoid arthritis (RA) and ankylosing spondylitis (AS).


Arthritis & Rheumatism | 2015

Identification of Susceptibility Loci in IL6, RPS9/LILRB3, and an Intergenic Locus on Chromosome 21q22 in Takayasu Arteritis in a Genome-Wide Association Study

Paul Renauer; Güher Saruhan-Direskeneli; Patrick Coit; Adam Adler; Kenan Aksu; Gokhan Keser; Fatma Alibaz-Oner; Sibel Zehra Aydin; Sevil Kamali; Murat Inanc; Simon Carette; David Cuthbertson; Gary S. Hoffman; Servet Akar; Fatos Onen; Nurullah Akkoc; Nader Khalidi; Curry L. Koening; Omer Karadag; Sedat Kiraz; Carol A. Langford; Kathleen Maksimowicz-McKinnon; Carol A. McAlear; Zeynep Ozbalkan; Aşkın Ateş; Yasar Karaaslan; Nurşen Düzgün; Paul A. Monach; Huseyin T. E. Ozer; Eren Erken

Takayasu arteritis is a rare large vessel vasculitis with incompletely understood etiology. This study was undertaken to perform the first unbiased genome‐wide association analysis of Takayasu arteritis.


Rheumatology International | 2005

Renin and angiotensin-converting enzyme (ACE) as active components of the local synovial renin-angiotensin system in rheumatoid arthritis

Veli Cobankara; Mehmet Akif Öztürk; Sedat Kiraz; I. Ertenli; Ibrahim C. Haznedaroglu; Salih Pay; Meral Calguneri

Local functional renin-angiotensin systems (RAS) have been demonstrated in many organ and tissue systems. Angiotensins, the effector growth factors of the RAS, are essentially cytokines and growth factors which actively contribute to many inflammatory reactions. Among the components of RAS, angiotensin-converting enzyme (ACE) and renin have been previously investigated separately in RA. In this study, ACE levels and renin concentrations were measured in the sera of 16 patients with RA (median age: 45 (26–69), male/female: 3/13), 13 patients with osteoarthritis (OA) (median age: 55 (28–72), male/female: 5/8), and 11 healthy adults (median age: 44 (35–70), male/female: 6/5). Synovial ACE levels and renin concentrations were also measured concurrently in patients with RA and OA. Serum ACE levels were comparable between the groups. However, synovial fluid ACE levels were significantly higher in the patients with RA than in patients with OA. Likewise, synovial fluid renin concentrations were higher in RA patients than in OA patients, while serum renin concentrations were similar in patients with RA and OA and in healthy controls. Moreover, there was a significant negative correlation between the duration of the disease and synovial renin concentrations in RA patients. In conclusion, locally-generated active renin and ACE could contribute to joint destruction in rheumatoid arthritis.


Renal Failure | 2008

The Relationship between the MEFV Genotype, Clinical Features, and Cytokine-Inflammatory Activities in Patients with Familial Mediterranean Fever

Bulent Colak; Bahar Gürlek; Zeynep Arzu Yegin; Serpil Muge Deger; Sehri Elbek; Hatice Pasaoglu; Ibrahim Dogan; Mehmet Akif Öztürk; Selahattin Unal; Galip Guz

Familial Mediterranean Fever (FMF) is an autosomal recessive disease characterized by periodic attacks of fever and polyserositis. The effects of the MEFV genotype differences on clinical picture and inflammatory activity have not been well documented. The aim of this study was to investigate levels of conventional inflammation markers, procalcitonin, interleukin levels, TNF-alpha, and C5a levels in patients with FMF who had different MEFV genotypes and compare them with those of healthy subjects. The study consisted of 41 patients with FMF (F/M: 23/18), and 31 healthy subjects (F/M: 18/13). Tests were performed during the attack-free period. White-blood cell count, CRP and IL-8 levels were higher in patients with FMF than in healthy subjects (p < 0.05) and also higher in M680I carriers than in the patients with M694V allele carriers. However, ESR, fibrinogen, procalcitonin, IL-6, C5a, TNF-alpha, and IgD levels were not significantly different between patients and healthy subjects (p > 0.05). Arthralgia or arthritis was significantly higher in M694V carriers than in non-M694V carriers (p < 0.05). It is concluded that the clinical features and inflammatory-cytokine activities were higher in patients with FMF during the attack-free period than in healthy subjects, and the different genotype might be related to different clinical pictures.


The Journal of Rheumatology | 2012

Initial diagnosis of lumbar disc herniation is associated with a delay in diagnosis of ankylosing spondylitis.

Vedat Gerdan; Servet Akar; Dilek Solmaz; Yavuz Pehlivan; Ahmet Mesut Onat; Bunyamin Kisacik; Mehmet Sayarlioglu; Cigdem Erhan; Mehmet Engin Tezcan; Mehmet Akif Öztürk; Fatos Onen; Nurullah Akkoc

Objective. There is often a considerable delay in diagnosis of ankylosing spondylitis (AS). In this multicenter study, we analyzed the delay and possible associated factors, including an initial diagnosis of lumbar disc herniation (LDH), which we frequently encounter in daily clinical practice. Methods. The study included 393 consecutive patients [258 men (65.6%), mean age 39.3 ± 10.8 yrs] with AS according to the modified New York criteria. Face-to-face interviews were done using a structured questionnaire, addressing all the potentially relevant factors. Results. The mean diagnostic delay was 8.1 ± 8.6 years in the whole study population. The shortest delay was observed when rheumatologists were the first physicians consulted (2.9 ± 5.3 yrs). An initial diagnosis of LDH was reported by 33% of the patients. The diagnostic delays in patients with an initial diagnosis of LDH and those without were 9.1 ± 8.5 years and 6.2 ± 7.4 years, respectively (p = 0.002). In a regression model, predictive factors for delay in diagnosis were age at onset of spondyloarthritic symptoms, back pain, education level, prior diagnosis of LDH, and surgical history for LDH. Conclusion. These results indicate the need to increase awareness of the concept of axial spondyloarthritis among specialists who might be the first physicians consulted by patients with AS for their back pain. There is also a need to develop strategies for early referral of such patients to rheumatologists.


Joint Bone Spine | 2008

Assessment of aortic wall stiffness in patients with Familial Mediterranean Fever

Yusuf Tavil; Mehmet Akif Öztürk; Kemal Üreten; Nihat Şen; Mehmet Gungor Kaya; Mustafa Cemri; Atiye Çengel

INTRODUCTION To evaluate aortic wall stiffness and its relation between the aortic stiffness and the left ventricular function in patients with Familial Mediterranean Fever (FMF). METHODS The study population was composed of 31 patients with FMF in attack-free period (12 men, 19 women; mean age: 36+/-7 years) and 27 healthy subjects (10 men, 17 women; mean age: 34+/-7 years) who had volunteered to participate. Aortic stiffness indices, aortic strain and distensibility, were calculated from the aortic diameters measured by echocardiography and blood pressure obtained by sphygmomanometry. RESULTS There were significant differences between the control and the patient group in aortic strain (mean (SD), 7.23+/-2.14 versus 4.91+/-1.66%, p=0.01) and distensibility (4.02+/-1.42 versus 2.84+/-1.46, 10(-6)cm(2)dyn(-1), p=0.001). Although there was no correlation between the aortic stiffness parameters and the left ventricular function parameters, there were significant negative correlations between the disease duration and aortic strain index (r=-0.29, p<0.001), and between the disease duration and distensibility (r=-0.32, p<0.001). CONCLUSION Aortic stiffness measurements were found abnormal in patients with FMF. We have also demonstrated that there were significant correlations between aortic stiffness parameters and disease duration.


Clinical Rheumatology | 2004

Successful treatment of rheumatoid arthritis is associated with a reduction in serum sE-selectin and thrombomodulin level

Veli Cobankara; Düzgün Özatli; Sedat Kiraz; Mehmet Akif Öztürk; I. Ertenli; Tufan Türk; Şule Apraş; Ibrahim C. Haznedaroglu; Meral Calguneri

The aim of this study was to investigate the changes in serum levels of endothelial cell injury markers, soluble (s) E-selectin and thrombomodulin (TM), in patients with rheumatoid arthritis (RA) before and after antirheumatic drug treatment and to assess the relationship between these changes and clinical responses to the drug treatment. Eleven patients with RA having active arthritis and 12 healthy volunteers were enrolled in the study. They were monitored by clinical and laboratory parameters while receiving a combination of methotrexate, hydroxychloroquine and sulphasalazine. Pre- and post-treatment clinical and laboratory parameters, including sE-selectin and sTM levels, were measured. The ages of the patients were comparable with those of the control groups. Significant improvements were detected in erythrocyte sedimentation rate, C-reactive protein, hemoglobin, morning stiffness, patients’ global assessment, physicians’ global assessment, number of tender joints and number of swollen joints improved at the end of the therapy (for each parameter p<0.05). Significant improvements were detected in clinical and laboratory parameters. In the patient group there were significant decreases in the levels of sTM and sE-selectin after treatment (p<0.05). The patient group had significantly higher sTM and sE-selectin levels than the control group at the beginning of the study (p<0.01), but the difference returned to normal after the treatment (p>0.05). The sE-selectin and sTM levels significantly correlated with each other, and also with clinical and laboratory findings. Combination treatment successfully treated RA patients. sE-selectin and sTM levels probably reflect disease activity and can be helpful in monitoring disease status and response to therapy.

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