Researcher: Ateş, Özkan
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Ateş, Özkan
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Publication Metadata only A study on the effects of direct factor Xa inhibitors and direct thrombin inhibitors on human primary chondrocyte cultures(Namık Kemal Üniversitesi, 2019) Kaya, Yasin Emre; Akalan, Hande; Yılmaz, İbrahim; Karaaslan, Numan; Özbek, Hanefi; N/A; Ateş, Özkan; Faculty Member; School of Medicine; 118533Aim:This study investigates the effects of two direct factor Xa inhibitors, apixaban and rivaroxaban, and a direct thrombin inhibitor, dabigatran, on human primary chondrocytecultures.Materials and Methods:Monolayer cultured chondrocytes were prepared. Cell cultures were treated with dabigatran, apixaban, and rivaroxaban. Cultures without drug treatments served as the control group. Using an inverted light microscope, the cell surface morphology was examined. Cell viability and the toxicity of drugs were evaluated using a commercial assay kit, and the results were confirmed using two nucleic acid binding dyes, acridine orange and propidium iodide. The expressions of cartilage oligomeric protein, matrix metalloproteinase-7, and matrix metalloproteinase-19 were assessed using the real-time polymerase chain reaction analysis. All the analyses were performed within 21 days. The data obtained were statistically evaluated.Results:The administration of the three drugs changed the cell viability, proliferation, and expressions of cartilage oligomeric protein, matrix metalloproteinase-7, and matrix metalloproteinase-19. The results were statistically significant (P<0.05).Conclusion:Results obtained from in vitro studies may not provide accurate and reliable insight for clinical practices. However, clinicians should know that drugs used for the prevention or treatment of diseases may suppress chondrocyte proliferation and damage the extracellular matrix formation. / Öz: Amaç: Bu çalışmada; direk faktör Xa inhibitörü apiksaban ve rivaroxaban ile Direk/selektif olarak thrombin inhibitörü olan dabigatranın, primer insan kıkırdak hücre kültürleri üzerine etkisinin gözlenmesi amaçlandı. Materyal ve Metot:Kondrosit kültürleri monolayer olarak çoğaltılldı. Bu kültürler üzerine apiksaban, dabigatran ve rivaroksaban farmasötik ajanları ilave edildi. İlaç uygulanmayan hücre kültürleri kontrol grubu olarak kullanıldı. Hücrelere ait yüzey morfolojisi invert ışık mikroskobisi ile değerlendirildi. Hücrelerin sağlıklı olup olmadığı ve proliferasyonlarının devam edip etmediği MTT analizi ile spektrofotometrik olarak belirlendi ayrıca AO/PI fluresan boyamalardan da yararlanılarak apoptotik hücre ölümü varlığı araştırıldı. Kıkırdak oligo matriks protein (COMP), matriks metalloproteinaz (MMP)-7 ve MMP-19 genlerine ait ifadeler ise quantitative real time polymerase chain reaction (qRT-PCR) ile test edildi. Tüm analizler 21 gün içinde gerçekleştirildi. Elde edilen veriler istatistiksel olarak değerlendirildi ve sonuçlarraporlandı. Bulgular:Bu üç farmakolojik ajanın, hem hücre canlılığı ve proliferasyonunu hem de COMP, MMP-7 ve MMP-19 genlerine ait ifadeleri değiştirdiği ve bu sonuçların istatistiksel olarak anlamlı olduğu kaydedildi (P<0.05). Sonuç:Her ne kadar in-vitro deneylerden elde edilen sonuçlar klinik uygulamaları tam olarak yansıtmıyor olsa bile, herhangi bir hastalığı önleyebilmek amacı ile uygulanan ilaçların, kondrosit proliferasyonunu baskılayabileceği ve/veya ekstraselüler matrix (ECM) yapısına zarar verebileceği gerçeği akıllardatutulmalıdır.Publication Metadata only Lumbar dynamic stabilization with 2-stage surgery: early results(Elsevier, 2022) HekimoǧLu, Mehdi Akgül, Turgut Özbek, Muhammet Arif; Özer, Ali Fahir; Ateş, Özkan; Sasani, Mehdi; Öktenoğlu, Bekir Tunç; Günerbüyük, Caner; Aydın, Ahmet Levent; Başak, Ahmet Tulgar; Faculty Member; Faculty Member; Faculty Member; Faculty Member; Teaching Faculty; Doctor; Doctor; School of Medicine; School of Medicine; School of Medicine; School of Medicine; School of Medicine; Koç University Hospital; School of Medicine; 1022; 118533; 219451; 220898; 380939; N/A; N/ABackground: Screw loosening, which is a major problem in dynamic systems, can be easily overcome with 2-stage surgery. In this article, the clinical and radiological results of patients undergoing dynamic stabilization with a Dynesys device in 2 stages are discussed. Methods: A total of 10 male and 13 female adult patients were included in this single-center retrospective study conducted between 2018 and 2021. The mean age of the patients was 65.6 years. All of the patients had pain complaints that affected their daily lives. Bone density T scores were determined with the dual-energy x-ray absorptiometry method before patients were admitted for surgery. In the first surgery, Dynesys system pedicle screws were inserted. After 6 months of osteointegration, Dynesys system spacers and elastic bandages were placed. Preoperative, early postoperative, and late postoperative visual analog pain scale (VAS) scores and Oswestry Disability Index (ODI) scores were determined and statistically compared. Results: Patients were followed for an average of 30 months. Complications and recurrence were not observed. Neurological deficits were not observed after patients recovered from anesthesia. Significant improvement was observed in the ODI and VAS parameters in the preoperative (ODI: 66.2%, VAS: 7.8), early postoperative (ODI: 20.3%, VAS: 2.4), and late postoperative (ODI: 6.8% and VAS: 1.1) periods. Symptomatic improvement was seen in all patients. No screw breakage or loosening was detected by radiological evaluation in any of the patients during the 2-year follow-up period. Conclusions: In our experience, the insufficiency of the proximal and distal end screws is eliminated when 2 stages of dynamic system stabilizations are completed after osteointegration of the screws.Publication Metadata only Evaluation of the effect of apixaban on the primary intact intervertebral disc cell cultures(İnönü Tıp Fakültesi, 2019) N/A; Ateş, Özkan; Faculty Member; School of Medicine; 118533Aim: Apixaban is a frequently preferred pharmacological agent in clinics to prevent deep vein thrombosis and pulmonary embolism. Such new oral anticoagulants may cause hemorrhage’s in tissues and/or organs or may cause gastrointestinal symptoms without bleeding. It is also reported in the literature that it may lead to mental disorders, unwanted disorders in the urinary tract and skeletalmuscle system. However, when the literature is examined, there are no studies, which are of high-evidential value, evaluating the efficacy of apixaban on healthy, intact intervertebral disc tissue, and matrix-like structures. In this pharmaco-molecular study, it was aimed to investigate the effects of a new oral anticoagulant agent containing the active ingredient apixaban on the intact intervertebral disc tissue cells, extracellular matrix (ECM) structure and to evaluate its positive and / or negative effects on gene expressions of cartilage oligo matrix protein (COMP), chondroadherin (CHAD), and Matrix Metalloproteinase (MMP)s. Material and Methods: The primary cell cultures were prepared from the intact tissues of the patients with the traumatic intervertebral disc herniation. Apixaban was administered to the cultures and molecular analyses were performed for 21 days. The data obtained from the apixaban-administered and non-apixaban-administered samples were evaluated statistically and the significance value was accepted as P<0.05. Results: The changes were observed in the cell proliferation and the expressions of the mentioned genes in the apixabanadministered group. The suppression of COMP value and the increase in MMP-13 value may be indicative of the development of matrix degeneration in the apixaban-administered group, compared to the non-drug-administered control group. Conclusion: The selectivity is one of the most important features of the drugs. However, it should not be forgotten that no drug will only produce the desired effect.Publication Metadata only Should iliac wing screws be included in long segment dynamic stabilization?(Cureus Inc, 2021) Hekimoglu, Mehdi; Cerezci, Onder; Basak, Ahmet T.; N/A; Özer, Ali Fahir; Aydın, Ahmet Levent; Ateş, Özkan; Öktenoğlu, Bekir Tunç; Sasani, Mehdi; Faculty Member; Doctor; Faculty Member; Faculty Member; Faculty Member; School of Medicine; N/A; School of Medicine; School of Medicine; School of Medicine; N/A; Koç University Hospital; N/A; N/A; N/A; 1022; N/A; 118533; 220898; 219451Background In this article, clinical sAtışfaction and radiological results are discussed in a series of patients where the iliac wings participate in dynamic stabilization. Dynamic stabilization is an effective alternative surgical treatment method, especially in clinical pictures that go with pain due to minor instabilities. Practically the unique surgical instrument used in multilevel instabilities is the Dynesys system. The most important drawback of the Dynesys system is that the S1 screws become loose in time. In this article, our aim is to find solution to S1 insufficiency by extension of the system to the iliac wings. Methods Nineteen patients (eight females, 11 males) with a mean age of 54.16 were included in the study. Patients had multilevel (level 2 and above) instability, iliac wings were included in the stabilized segments, and Visual Analog Scale (VAS) and Oswestry Disability Index (ODI) were used for patient follow-up. Results First year results showed a significant improvement in VAS and ODI. Regarding the complications, infection developed in one patient, loosening in the proximal iliac wing in one patient, and both S1 and iliac proximals in one patient, but no clinical findings were encountered. Conclusion When more than two levels of dynamic systems are used in chronic instability, especially in the elderly patients, S1 screws are loosened. In these patients, if the iliac bones are also included in stabilization, this problem is solved successfully. However unfortunately, Dynesys system does not have a screw suitable for the iliac bones.Publication Metadata only Foraminoplasty with partial pediculectomy in degenerative spondylolisthesis cases with nerve compression(Elsevier Inc., 2023) Toklu, Sureyya; N/A; Akgün, Mehmet Yiğit; Günerbüyük, Caner; Ateş, Özkan; Aydın, Ahmet Levent; Baran, Oğuz; Öktenoğlu, Bekir Tunç; Sasani, Mehdi; Özer, Ali Fahir; Doctor; Teaching Faculty; Faculty Member; Doctor; Faculty Member; Faculty Member; Faculty Member; Faculty Member; N/A; School of Medicine; School of Medicine; N/A; School of Medicine; School of Medicine; School of Medicine; School of Medicine; Koç University Hospital; N/A; 380939; 118533; N/A; 291138; 220898; 219451; 1022Background: Degenerative spondylolisthesis refers to a forward displacement of a vertebra relative to the underlying vertebra. Patients with radicular pain and/or neurogenic claudication are considered suitable candidates for surgical intervention. The aim of this study was to present clinical results of dynamic stabilization applied after pediculectomy and neural foramen enlargement in patients with degenerative spondylolisthesis and normal spinal sagittal balance. Materials and Methods: All patients who underwent pediculectomy and dynamic stabilization for lumbar degenerative spondylolisthesis were retrospectively identified. Diagnosis was made with detailed neurological and radiological imaging examinations for the anatomical location of the pain. Demographic data, visual analog scale scores, and quality-of-life scores were obtained. Results: Patients included 3 (33.3%) men and 6 (66.7%) women with a mean age of 61.3 ± 13.0 years (range, 46–80 years) at initial symptom onset. Grade 1 degenerative spondylolisthesis was present in 5 (55.6%) patients, and grade 2 was present in 4 (44.4%) patients. Pathology was detected in L4-5 in 4 patients (44.4%) and L5-S1 in 5 patients (55.6%). In all patients, at the 3-month follow-up, statistically significant decrease in visual analog scale and Oswestry Disability Index scores was observed. At the last follow-up, no implant-related complications requiring revision were observed. Conclusions: In patients without any pathology in the sagittal balance, the optimal physiological treatment modality can be created by applying posterior dynamic stabilization together with pediculectomy to support the posterior tension band. © 2023 Elsevier Inc.Publication Metadata only Investigation of the effect of dipyrone on cells isolated from intervertebral disc tissue(Spandidos Publications, 2019) Akgün, Feride Sinem; Şirin, Duygu Yaşar; Yılmaz, İbrahim; Karaarslan, Numan; Özbek, Hanefi; Şimsek, Abdullah Talha; Kaya, Yasin Emre; Kaplan, Necati; Akyuva, Yener; ÇalIşkan, Tezcan; N/A; Ateş, Özkan; Faculty Member; N/A; 118533The present study aimed to evaluate the effects of dipyrone, an indispensable analgesic, anti-pyretic and anti-spasmodic used in emergency departments, on nucleus pulposus and annulus fibrosus cells in vitro. After surgical biopsy, primary cell cultures were prepared from intact intervertebral disc tissues. Dipyrone was administered to the cultures in the experimental groups except for the control group. The data obtained were statistically evaluated. The proliferation was identified to be suppressed via MTT analysis. The gene expression profile of the intervertebral disc cells in the dipyrone-treated groups was significantly changed. The expression of chondroadherin, cartilage oligo matrix protein, interleukin-1β and metalloproteinase (MMP)-19 genes were decreased, but MMP-13 and MMP-7 genes expressions were increased, as determined via reverse transcription-quantitative PCR. AO/PI staining revealed that no apoptotic or other type of cell death was detectable after administration of dipyrone does not mean that the drug is innocuous. The occurrence of cellular senescence and/or the halt of cell proliferation may also be important mechanisms underlying the adverse inhibitory effects of dipyrone. Therefore, prior to administering dipyrone in clinical practice, all possible adverse effects of this drug should be considered.Publication Metadata only Is favipiravir a potential therapeutic agent in the treatment of intervertebral disc degeneration by suppressing autophagy and apoptosis?(Buluş Design, 2022) Yilmaz, Ibrahim; Akalan, Hande; Sirin, Duygu Yasar; Karaarslan, Numan; Ozbek, Hanefi; N/A; Ateş, Özkan; Faculty Member; School of Medicine; 118533Aim: To evaluate the effects of favipiravir (FVP) on cell viability and cytotoxicity in human degenerated primary intervertebral disc (IVD) tissue cell cultures. Furthermore, the protein expressions of hypoxia-inducible factor 1 alpha (HIF-1 alpha), nuclear factor-kappa-b (NF-kappa B), and interleukin-1 beta (IL-1 beta) were also examined. Material and Methods: Untreated cell cultures served as the control group, named group 1. Cell cultures treated with FVP served as the study group, named group 2. Pharmacomolecular analyses were performed in all groups at 0, 24, 48, and 72 hours (h). Obtained data were evaluated statistically. Results: Cell proliferation was suppressed in the FVP-treated samples compared to the control group samples at 24 and 72 h, and this was statistically significant (p<0.05). Decreased or increased protein expression levels of HIF-1 alpha, NF-kappa B, and IL-1 beta in FVP-treated samples may be an indication of suppression in anabolic events as well as proliferation in IVD cultures. FVP administration showed that AF/NP cells in a culture medium may induce a strong inflammatory response to FVP. This strong inflammatory response is likely to cause slowed proliferation. It may also be a trigger for many catabolic events. NF-kappa B expression increased within the first 24 h and then decreased rapidly. Based on the data obtained, it may be suggested that the rapidly increasing NF-kB may have stimulated the expression of many antiproliferative genes. Conclusion: The suppression of IL-1 beta and NF-kB protein expressions in IVD cells treated with FVP is important in the treatment of IVD degeneration (IDD). If the protein expression of HIF-1 alpha could be increased along with the suppression of IL-1 beta and NF-kB, FVP would perhaps be a promising pharmacological agent in the treatment of IDD.Publication Metadata only Preoperative magnetic resonance imaging abnormalities predictive of lumbar herniation recurrence after surgical repair(Elsevier Science Inc, 2022) Karadag, Mehmet Kursat; Akinci, Ahmet Tolgay; Basak, Ahmet Tulgar; Hekimoglu, Mehdi; Yildirim, Hakan; Akyoldaş, Göktuğ; Aydın, Ahmet Levent; Ateş, Özkan; Öktenoğlu, Bekir Tunç; Sasani, Mehdi; Akgün, Mehmet Yiğit; Özer, Ali Fahir; Günerbüyük, Caner; Faculty Member; Doctor; Faculty Member; Faculty Member; Faculty Member; Doctor; Faculty Member; Teaching Faculty; N/A; School of Medicine; School of Medicine; School of Medicine; School of Medicine; N/A; School of Medicine; School of Medicine; Koç University Hospital; 203677; N/A; 118533; 220898; 219451; N/A; 1022; 380939Objective: There are currently no standard criteria for evaluating the risk of recurrent disk herniation after surgical repair. This study investigated the predictive values of 5 presurgical imaging parameters: paraspinal muscle quality, annular tear size, Modic changes, modified Phirrmann disk degeneration grade, and presence of sacralization or fusion. Methods: Between 2015 and 2018, 188 patients (89 female, 99 male, median age 50) receiving first corrective surgery for lumbar disk herniation were enrolled. Micro-diskectomy was performed in 161 of these patients, and endoscopic translaminar diskectomy approach was performed in 27 patients. Clinical status was evaluated before surgery and 4, 12, and 24 months post surgery using a visual analog scale, Oswestry Disability Index, and Short Form 36. Results: Recurrent disk herniation was observed in 21 of 188 patients. Seventeen of the recurrent disk herniations were seen in those who underwent microdiskectomy and 4 in those who underwent endoscopic translaminar diskectomy. There were significant differences in visual analog scale, Oswestry Disability Index, and Short Form 36 scores at 4, 12, and 24 months between patients with recurrence and the 167 no-recurrence patients. The median annular tear length was significantly greater in patients with recurrence than without recurrence. In addition, there were significant differences in recurrence rate according to Modic change type distribution, sacralization or fusion presence, Pfirmann disk; degeneration grade distribution, dichotomized annular tear size, dichotomized Modic change; and type and simplified 3-tier muscle degeneration classification distribution. Conclusions: Patients with poor clinical scores and recurrence exhibited additional radiologic abnormalities before surgery, such as poor paraspinal muscle quality, longer annular tears, higher Modic change type, higher modified Phirrmann disk degeneration grade, and sacralization or fusion. This risk evaluation protocol may prove valuable for patient selection, surgical planning, and choice of postoperative recovery regimen.Publication Metadata only Investigation of the effects of tigecycline, a semi-synthetic derivative of minocycline, on chondrocyte cultures(İnönü Tıp Fakültesi, 2020) Kaya, Yasin Emre; Karaarslan, Numan; Yılmaz, İbrahim; Şirin, Duygu Yaşar; Yaman, Onur; Özbek, Hanefi; N/A; Ateş, Özkan; Faculty Member; School of Medicine; Koç University Hospital; 118533Aim: Although antibiotics are generally well-tolerated, they may have cytotoxic effects. The present randomized, double-blind, in vitro study aimed to investigate the effects of tigecycline on cartilage tissue cells and the extracellular matrix. Material and Methods: Cartilage tissues of patients (n = 8) were used for the preparation of primary cell cultures. Tigecycline-treated cell cultures served as the study group. Non-treated cell cultures served as the control group. Analyses were performed at 0, 24, 48, and 72 h in both groups. The results obtained were statistically evaluated. The alpha significance value was determined to be 0.05. Results: Proliferation remained unchanged in the tigecycline-treated cell cultures. The gene expressions of the markers involved in anabolic pathways increased in the tigecycline-treated cell cultures. The results obtained were statistically significant (P < 0.05). Conclusion: Although tigecycline had no toxic effect on the chondrocyte cell cultures and caused no damage to the extracellular matrix, the present study was performed in an in vitro environment.Publication Metadata only Challenges in using the posterior inferior cerebellar artery for revascularization of the anterior inferior cerebellar artery: a microsurgical anatomic study(Elsevier, 2021) Keser, Nese; Elshamy, Walid; Chen, Xinpu; Velioglu, Murat; Is, Merih; Xu, Yinfu; Eroksuz, Melih; Ermutlu, Ilcim; Huryol, Cagin; Jian, Ruan; N/A; Ateş, Özkan; Faculty Member; School of Medicine; 118533Background: A bypass is usually required to prevent ischemia during the treatment of anterior inferior cerebellar artery (AICA) aneurysms. The intracranial (IC)-to-IC bypass provides several advantages over the extracranial-to-IC bypass in the posterior fossa. However, there are only 2 case reports about AICA revascularization with the posterior inferior cerebellar artery (PICA). We aimed to investigate the microsurgical anatomical challenges for PICA to AICA anastomosis. Methods: Ten cadaveric heads injected with colored silicone were inspected on both sides using a lateral transcondylar approach. After the donor and recipient arteries were examined from the posterior side, neurovascular contents of the posterior fossa were excised and the origin, course, and variations of both arteries were investigated from the anterior view. The diameters of the AICA and PICA segments and the intersegment distance were measured. Results: PICA variations and posteromedial origins from the vertebral artery were identified in 8 of the 20 right and 6 of the 20 left sides, and the first segment of the PICA was not present in 7 sides. Furthermore, in 18 sides, the PICA was trapped between the lower cranial nerves and dentate ligaments. Therefore the donor artery could not be brought closer than 1 cm to the recipient artery in 19 sides. Moreover, AICA variations were identified in 6 sides, and in 12 sides, the diameter of the recipient artery was <1 mm. Conclusions: The mostly PICA-related issues made PICA-to-AICA anastomosis unfeasible in all cadaveric heads included in the study.