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YILDIRIM, ALPER

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YILDIRIM

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ALPER

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    PublicationOpen Access
    Comparative design improvement of the growing rod for the scoliosis treatment considering the mechanical complications
    (2023-01-01) AKGÜN, GAZİ; YILDIRIM, ALPER; DEMİR, UĞUR; DEMİR U., AKGÜN G., KOCAOĞLU S., Okay E., Heydar A., AKDOĞAN E., YILDIRIM A., Yazi S., Demirci B., Kaplanoglu E.
    In this study, the focus is on an implant used in the treatment of early-onset scoliosis called magnetically controlled growing rods (MCGR). The primary goal of the study is to address and propose solutions for the mechanical problems reported in the literature concerning MCGR. The problems of the MCGR are mainly due to excessive stress and mechanical bearing problems. Therefore, an MCGR removed from a patient is teardown and geometrically modeled. Then, eleven design parameters are determined on the MCGR for the mechanical problems experienced and these are evaluated by mechanical analysis over 14 control points. In this study, analysis processes are carried out with L12 orthogonal array for eleven design parameters and 2 levels using Taguchi’s experimental design method (DoE). With the obtained data by analyzing the experiments in L12, the fitness functions depending on the design parameters are created for 14 control points. Since the problem is multi-objective, a non-dominated sorting genetic algorithm (NSGA II) and multi-objective particle swarm optimization (MOPSO) are used to minimize stress and displacement in existing mechanical problems using fitness functions. The obtained design models from NSGA II and MOPSO are analyzed and evaluated in comparison with the existing mechanical model obtained through pre-optimization teardown study of MCGR.
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    PublicationOpen Access
    Cerrahi menopoz oluşturulmuş sıçanların karaciğer ve böbrek dokularında oksidan/antioksidan dengenin korunmasında egzersizin ve östrojenin yararlı etkileri
    (2022-09-01) YÜKSEL, MERAL; ERCAN, FERİHA; YILDIRIM, ALPER; YEGEN, BERRAK; Tamer S. A. , Levent N., Yüksel M., Ercan F., Yıldırım A., Yegen B.
    Amaç: Bu çalışmanın amacı cerrahi olarak menopoz oluşturulan sıçanların böbrek ve karaciğerlerinde gözlenen histopatolojik ve fonksiyonel değişiklikleri ve östrojen veya egzersizin ya da östrojen-egzersiz kombinasyonunun oksidan hasar üzerine etkilerini araştırmaktır.Materyal ve Metot: Anestezi altında Sprague Dawley dişi sıçanlara (n=32) bilateral overiektomi uygulandı ve tüm sıçanlar rastgele olarak iki gruba ayrıldı. Sıçanların yarısına normal içme suyu, diğer yarısının içme sularına östrojen (1mg/kg/gün) eklendi. İki hafta sonra gruplar kendi içlerinde sedanter ve egzersiz (5 gün/hafta, 30 daki-ka, 8 hafta) gruplarına ayrıldı. Deney protokolünün sonun-da serum, karaciğer ve böbrek örnekleri biyokimyasal ve histopatolojik incelemeler için alındı. Femurda da histopa-tolojik değerlendirme yapıldı.Bulgular: Cerrahi olarak menopoz oluşturulan sıçan-larda östrojenin böbrek dokusunda nötrofil infiltrasyonunu ve reaktif oksijen türlerinin üretimini baskılayarak koruyu-cu etki gösterdiği, kemik kütlesinde hafif düzeyde artışa neden olduğu, ancak karaciğerin antioksidan glutatyon düzeyinde azalmaya yol açtığı belirlenmiştir. Buna karşın, östrojen uygulaması menopozda yapılan egzersiz nedeniy-le karaciğerde oluşan oksidan stresi engellemiştir. Egzer-sizle veya egzersize östrojen tedavisinin eklenmesiyle böbrek fonksiyonları önemli ölçüde etkilenmezken, kemik yapısında tek başına östrojene kıyasla daha olumlu deği-şiklikler gözlenmiştir.Sonuç: Östrojen replasmanı kemik dokusundaki olum-lu etkilerinin yanı sıra karaciğer ve böbrekte oksidan stresi azaltmakta ve özellikle karaciğerde egzersize bağlı gelişen oksidan stresi baskılayarak koruyucu etki göstermektedir.
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    PublicationOpen Access
    Melatonin alleviates ovariectomy-induced cardiovascular inflammation in sedentary or exercised rats by upregulating SIRT1
    (2022-12-01) ERCAN, FERİHA; YILDIRIM, ALPER; YEGEN, BERRAK; Arabacı Tamer S., Altınoluk T., Emran M., Korkmaz S., Yüksel R. G., Baykal Z., Dur Z. S., Levent H. N., Ural M. A., Yüksel M., et al.
    © 2022, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.We aimed to evaluate the impact of hormone replacement, melatonin, or exercise alone or their combination on oxidative damage and functional status of heart, brain, and aorta of ovariectomized (OVX) rats and to determine whether the signaling pathway is dependent on sirtuin-1 (SIRT1). Ovariectomized Sprague Dawley rats were orally given either a hormone replacement therapy (1 mg/kg/day,17β estradiol; HRT) or melatonin (4 mg/kg/day) or HRT + melatonin treatments or tap water, while each group was further divided into sedentary and exercise (30 min/5 days/week) groups. After the heart rate measurements and memory tests were performed, trunk blood was collected at the end of the 10th week to determine metabolic parameters in serum samples. Tissue samples of abdominal aorta, heart, and brain were taken for biochemical measurements and histopathological evaluation. Heart rates and memory performances of the OVX rats were not changed significantly by none of the applications. Melatonin treatment or its co-administration with HRT upregulated the expressions of IL-10 and SIRT1, reduced the expressions of IL-6 and TNF-α, and reduced DNA damage in the hearts and thoracic aortae of non-exercised rats. Co-administration of melatonin and HRT to exercised OVX rats reduced inflammatory response and upregulated SIRT1 expression in the aortic and cardiac tissues. The present study suggests that melatonin treatment, either alone or in combination with exercise and/or HRT, upregulates SIRT1 expression and alleviates oxidative injury and inflammation in the hearts and aortas of OVX rats. Melatonin should be considered in alleviating cardiovascular disease risk in postmenopausal women.
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    PublicationOpen Access
    Impaired vasomotor function induced by the combination of hypertension and hypercholesterolemia
    (ELSEVIER SCIENCE INC, 2013-01) YILDIRIM, ALPER; Kurtel, Hizir; Rodrigues, Stephen F.; Yilmaz, Cigdem E.; Yildirim, Alper; Granger, D. Neil
    Although it is well known that endothelial function is compromised in the presence of either hypertension (HTN) or hypercholesterolemia (HCh), less is known about whether and how the combination of these risk factors (HTN+HCh) results in impaired endothelium-dependent dilation (EDD). The aims of this study were to evaluate the influence of HTN+HCh on vasomotor function and to identify the mechanisms that underlie the altered vascular reactivity elicited by HTN+HCh. Endothelium-dependent and -independent vasomotor responses of aortic vessels were studied in mice with diet-induced HCh and/or HTN induced by chronic administration of either angiotensin II (AngII) or deoxycorticosterone acetate-salt. HTN+HCh elicited an impairment of EDD that appeared between each risk factor alone. Incubation with catalase resulted in more severe EDD impairment. Each risk factor enhanced vascular H2O2 production, but a larger response was noted with HTN+HCh. An attenuated EDD was not observed in AngII type la receptor deficient (AT1r(-/-)) mice, but AT1r(-/-) bone marrow chimeras exhibited more profound impairment compared with wild-type. HTN+HCh does not exert an additive effect of vasomotor dysfunction compared with either risk factor alone, and both H2O2 and blood cell-associated AT1r contribute to the impaired EDD responses in mice with HTN+HCh. J Am Soc Hypertens 2013;7(1):14-23. (C) 2013 American Society of Hypertension. All rights reserved.
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    PublicationOpen Access
    A 10-day mild treadmill exercise performed before an epileptic seizure alleviates oxidative injury in the skeletal muscle and brain tissues of the rats
    (2022-01-01) KAYA, ÖZLEM TUĞÇE; YEGEN, BERRAK; YÜKSEL, MERAL; YILDIRIM, ALPER; Arabaci -Tamer S., KAYA Ö. T., YÜKSEL M., YILDIRIM A., YEGEN B.
    © 2022 Marmara University Press, All Rights Reserved.Objective: Epileptic seizures may cause skeletal muscle injury and memory dysfunctions. The present study was aimed to investigate the possible protective effects of exercising prior to seizure on seizure-induced oxidative injury in the skeletal muscle and brain. Materials and Methods: Sprague-Dawley male rats were assigned as non-exercise (n=16) and exercise groups (n=16). Following a 3-day exercise training, exercise protocol (30 min) was performed on a treadmill for 10 days, while control rats had no exercise. On the 11th day, the epileptic seizure was induced by a single intraperitoneal injection of pentylenetetrazol (PTZ) (45 mg/kg), while the control groups were injected with saline. Passive-avoidance test was initially performed before PTZ/saline injection and repeated 72 h later for the assessment of memory function. Brain and gastrocnemius muscles were taken for histological assessments and to determine the levels of malondialdehyde (MDA) and glutathione (GSH), myeloperoxidase (MPO) activity and luminal – and lucigenin – enhanced chemiluminescence levels. Results: Exercise training alone increased the formation of reactive oxygen species and elevated the antioxidant GSH capacity of the muscle tissue in the control rats, but these effects were not observed in the muscles of the exercised rats induced with a PTZ-seizure. On the other hand, short-term exercise alone had no effect on the basal oxidative parameters of the brain tissues. Prior exercise did not alter the average seizure scores or memory performances when compared to non-exercised groups, but suppressed the PTZ-induced elevations in MDA and chemiluminescence levels as well as MPO activity in the brain. Conclusion: A 10-day mild treadmill exercise reduced the oxidative brain damage due to a single seizure-induced excitotoxicity and exerted a preconditioning effect on the skeletal muscles exposed to tonic-clonic contractions.