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Öğe Can hypo/hypernatremic conditions be a factor for na ion channel kinetics: model study(Turkish Neurosurgical Soc, 2018) Ayaz, Murat; Karabagli, Hakan; Yanardag, Sirma BasakAIM: Dysnatremic cases are frequently faced in clinical practice. Its macroscopic effects and consequences are well known, but microscopic effects are not well defined. The aim of this study was to reveal the effects of dysnatremia at the cellular level. MATERIAL and METHODS: By using an action potential simulation, the effects of extracellular sodium (Na) concentration on the Na ion channel kinetics were studied. The experimental sets were chosen to mimic hypo/hypernatremic conditions and, in both cases, the degree of the severity was varied. RESULTS: Hyponatremic situations through modifying the axonal Na+ channels kinetics result in the rundown of the sodium current (INa). The degree of the hyponatremia-dependent effect seen in the Na ion channel is severity dependent, which is more effective in the recovery phase of the ion channel. Hypernatremic conditions, on the other hand, have also affected the Na ion channel activity through modifying the kinetics of the channel. Unlike hyponatremia, the effect seen in hypernatremic conditions was through decreasing the response time of the channel. The degree of the significance of the effect seen on the Na ion channel in the case of the hypernatremia was found to be less destructive compared to the hyponatremic condition. CONCLUSION: The Na channels are susceptible to the changes of the extracellular Na concentrations. Thus, the underestimation of hypo/hypernatremic conditions can put patients in danger and close monitoring of serum Na level might be required.Öğe Coenzyme Q(10) and alpha-lipoic acid supplementation in diabetic rats: Conduction velocity distributions(PROUS SCIENCE, SAU-THOMSON REUTERS, 2008) Ayaz, Murat; Tuncer, Seckin; Okudan, Nilsel; Gokbel, HakkiDiabetic neuropathies are a family of nerve disorders caused by diabetes. Patients with diabetes can develop nerve problems at any tune, but the longer a person has diabetes the greater the risk. This study aims to investigate diabetes- and coenzyme Q(10) (CoQ(10)) or alpha-lipoic acid (ALA) supplementation-induced changes in the conduction velocity (CV) distributions of rat sciatic nerve fibers. Sciatic nerve compound action potentials (CAPs) were recorded by suction electrode and CV distributions by the collision technique. Diabetes resulted in a significant increase in time to peak, rheobase and chronaxie values of these CAP waveforms, whereas the maximum depolarization, area, kinetics and CVs of both fast and slow nerve fiber groups were found to be decreased, Coenzyme Q(10) (CoQ(10)) supplementation was found to have some positive effect on the diabetes-induced alterations. CoQ(10) supplementation induced positive changes mainly, in the area and fall-down phase of the kinetics of CAP waveforms, as well as rheobase. chronaxie and speed of the intermediately conducting groups (congruent to 40 m/s). alpha-Lipoic acid (ALA) supplementation did not produce statistically significant effects. This stud), has shown for the first tune that diabetes induces a shift of actively contributing nerve fibers toward slower CVs(10) and supplementation with CoQ(10) not only stopped this shift but also tended to restore velocities toward those of the age-matched control group. In addition to its effects on mitochondrial alterations, these positive effects of CoQ(10) on diabetic neuropathy) can be attributed to its antioxidant activity Copyright 2008 Prous Science, S.A.U. or its licensors. All rights reserved.Öğe Controlled Trial of Efficacy of Dexketoprofen in Sciatic Nerve Crush Injury in Rats(2014) Kaptan, Hulagu; Kasımcan, Omur; Ayaz, Murat; Bozdogan, Onder; Karabaglı, HakanAmaç: Bu çalışmanın amacı, sıçanlarda siyatik sinir ezilme yaralanmalarında lokal olarak uygulanan deksketoprofen'in etkilerini karşılaştırmaktır. Bunun için sıçan modelinde yaralı siyatik sinirlerin Siyatik Fonksiyon Endeksi ( SFI ), Refleks Bacak geri çekilmesi (WRL), akson sayısı, parametreleri üzerinde 1 gün, 5 gün ve kontrol gruplarında akson çapı ve sinir çapı birlikte değerlendirilerek nöronal hasar incelendi. Yöntem ve Gereç: Wistar albino sıçanlar ( 21 hayvan ) kullanıldı. Sağ siyatik sinir bir Aesculap - Yaşargil anevrizma kullanılarak 10 saniye ezildi ve 10 saniye sonra anevrizma klibi açıldı. Deney hayvanları Grup 1, Grup 2 ve Grup 3 olarak üç gruba ayrıldı. Duyusal fonksiyonun iyileşmesi WRL ile değerlendirildi . Histo-patolojik inceleme yapıldı. Bulgular: Akson sayısı, akson çapı ve sinir çap bazında gruplar arasında anlamlı fark yoktu. Ama yaralanma indüksiyonundan sonra, istatistiksel olarak anlamlı fonksiyonel testler görüldü. Bu etki yalnızca çok dozlu Dex uygulamalarında etkili olarak bulundu. Sonuç: Bu çalışma; 5 gün üst üste deksketoprofen trometamol uygulanmasının, analjezik etkisi ile siyatik sinir hasarı üzerinde olumlu önemli etkilerinin olduğunu ortaya çıkarmıştır.Öğe Controlled Trial of Efficacy of Dexketoprofen in Sciatic Nerve Crush Injury in Rats(JOURNAL NEUROLOGICAL SCIENCES, 2014) Kaptan, Hulagu; Kasimcan, Omur; Ayaz, Murat; Bozdogan, Onder; Karabagli, HakanObject: Local applications of Dexketoprofen trometamol (dex) have been shown to increase in the sciatic nerve functional tests following the nerve injuries. The aim of the current study was to compare the efficacy of dex application for 1 and 5 days following nerve injury rat model. Possible effects of dex were checked by means of the Sciatic Function Index (SFI), Withdrawal of the Reflex Leg (WRL), number of axons, axon diameter, and nerve diameters. Material Methods: The animal crushed model was done through Aesculap -Yasargil aneurysm method on Wistar albino (N=21) right sciatic nerves. In order to achieve desired purpose 3 experimental groups were organized: Group 1: control (injured and no drug); Group2: dexketoprofen 1 days (injured and single dose of drug); Group3: dexketoprofen 5 days (injured and single dose of 5 times drug applications). Injections were done through the tissue expander's injection port with a connecting tube directed at the crush-injured site. Functional recovery of the sciatic nerves was evaluated with the improvement in the SFI values. Additionally, recovery of sensory function was assessed through WRL results and histopathological examination was performed 6 week following the injury. Results: At the end of the experimental periods there was no significant differences were found between the experimental group of animals on the bases of the number of axons, axon diameter, and nerve diameter. Moreover, up 30th day of the experimental period our functional test results have shown that there was no difference between the groups. But following the induction of the injury, the statistical significances were seen on the functional tests. This effect was seen only if the multi-dose application of the dex. Conclusions: This study suggests that; dexketoprofen trometamol of 5 consecutive days, has revealed positive significant changes in the sciatic nerve injury through analgesic effect of it.Öğe A Critical Balance Between Oxidative Stress and Antioxidant Defense in Cardiovascular System Under Hyperglycemia: A Summary of Experimental Studies(SPRINGER, 2014) Ayaz, Murat; Turan, BelmaDiabetes mellitus is a disorder resulting from a lost in control of blood glucose level by insufficient insulin release (type 1), impaired insulin function, or insulin resistance (type 2). The main etiology for mortality and a great percent of the morbidity in patients with diabetes is cardiovascular disease. In addition to hyperglycemia, enhanced oxidative stress plays a major role in the pathogenesis of diabetes. Although reactive oxygen species (ROS) are known to be mediators of intracellular signaling pathways under physiological conditions, excessive production of ROS can be detrimental to the cells as a result of increased oxidative stress and thereby cellular dysfunction. Hence, well-tuned, balanced, and responsive antioxidant systems are vital for proper regulation of the redox status of the cells. Studies have reported valuable effects of antioxidant agents, including trace elements, on diabetes-induced cardiovascular system dysfunctions, either directly or indirectly. Thus, several approaches have been carried out to either diminish an elevated ROS production or improve the endogenous levels of antioxidants. Indeed, reduced fatty acid oxidation and use of trace elements in treatment strategies result in promising prevention hints for diabetes-induced cardiovascular dysfunctions. Our scope here is to review the important role of antioxidants, particularly selenium, as cardioprotective agents in several types of disease states including diabetes, presenting our research results on cardiac function by using experimental animal models for diabetes. Although the paradigm that inhibiting overproduction of superoxides and peroxides would prevent cardiac dysfunction diabetes-induced damage has been difficult to verify using conventional antioxidants such as selenium, of special note is that its role as hyperglycemia controller, insulin sensitizer, or antioxidant therapy remains to be further explored as well as the effect of hypolipidemic therapy.Öğe Effect of sex steroids on soleus muscle response in hypocalcemic medium (in vitro)(ACADEMIC PRESS INC ELSEVIER SCIENCE, 2013) Kökçam, Süleyman Said; Tekin, Şakir; Kartal, Adıl; Ayaz, Murat; Şahin, Mustafa; Acar, Fahrettin; Çakır, MuratPurpose: Postoperative hypocalcemia is a frequently encountered complication of thyroid surgery. Since hypocalcemic symptoms are closely associated with sex, the aim of this study is to investigate the effects of sex steroids on muscle tissue under hypocalcemic conditions. Methods: Six groups consisting of control male (M), control female (F), gonadectomized male (M -), gonadectomized female (F-), estradiol- applied gonadectomized male (MX), and testosterone- applied gonadectomized female (FX) rats were used. Contraction recordings were obtained from soleus muscle flaps. Maximal tension (PT), frequency required for 50% of PT (F50), contraction velocity at F50 (V50), and changes in contraction values (d[PT], d[F50], d[V50]) between normocalcemic and hypocalcemic conditions were calculated. Results: d[PT], d[F50], and d[V50] were significantly higher in M - and MX groups compared with control M group. Whereas d[PT], d[F50], and d[V50] parameters of the F- group were significantly higher than control F group, d[F50] and d[PT] of the FX group showed no significant change and d[V50] for the FX group was significantly lower. A comparison of control groups showed that d[PT], d[F50], and d[V50] of the F group were significantly higher than those of the M group. Conclusion: Whereas absence of both testosterone and estradiol caused an increase in hypocalcemia- induced changes in contraction parameters of rat skeletal muscle, presence or application of testosterone clearly stabilized contraction parameters. (C) 2013 Elsevier Inc. All rights reserved.Öğe Effects of selenium on electrophysiological changes associated with diabetic peripheral neuropathy(WOLTERS KLUWER MEDKNOW PUBLICATIONS, 2011) Ayaz, Murat; Kaptan, HulaguOur previous study has demonstrated that sodium selenite prevents oxidative stress, suggesting that selenium can improve diabetic peripheral neuropathy. Results from this study demonstrated that diabetes mellitus resulted in significant increased time to peak, as well as rheobase and chronaxie values. In addition, maximum depolarization, area under compound action potential, kinetics, and conduction velocities of fast and slow nerve fiber groups were decreased. Sodium selenite exhibited positive effects on alterations of diabetes mellitus-induced conduction velocity distribution. This neuroprotective effect was primarily observed in the area under compound action potential and compound action potential kinetic waveforms, as well as rheobase and chronaxie. Results from this study showed that selenium supplementation blocked the diabetes mellitus-induced shift of actively contributing nerve fibers, and restored levels towards age-matched control group values. Chronic selenate supplementation for experimental diabetic peripheral neuropathy exhibited protective effects in measured electrophysiological parameters.Öğe Electrophysiology of papillary muscle in SAH: changes and N-acetylcysteine protection(SPRINGER, 2009) Ayaz, Murat; Guney, Onder; Erdi, Fatih; Kucukbagriacik, YusufAlthough subarachnoid hemorrhage (SAH) serves as a good model to study heart-brain interactions, neither the changes on the single ventricular action potential (SVAP) and contraction nor the effects of possible cardioprotective agents have been investigated. A total of 18 male rabbits were used for the three experimental groups. SAH was induced by replacing the cerebrospinal fluid (CSF) with fresh autologous blood at the ratio of 1 mL to the 1-kg body mass (N = 6). In the control (CON; N = 6) group, the CSF was replaced with serum physiologic at the same ratio. The treated SAH group (SAH+NAC) received daily intraperitoneal N-acetylcysteine (NAC; 150 mg/kg for 3 days) starting from just before SAH was induced by CSF replacement. On the fourth day, animals were examined for the single action potential and contraction recordings from the left ventricular papillary muscle. At the end of 3 days, the overshoot decreased together with increased time to reach the peak potential. Additionally, the resting membrane potential was depressed and repolarization was slowed during SVAPs. On the other hand, peak tension depressed and time to peak increased. NAC treatment, which protects infarction in the brain, prevented these pathological changes in the cardiac muscle. SAH-induced cardiac changes can be attributed to adenosine triphosphate depletion through mitochondrial dysfunction. Pretreatment of NAC to SAH on the other hand had a positive effect on these cardiac changes. But the exact mechanism by which NAC treatment protects the cardiac muscle needs further investigation.Öğe Expectation from science/Prevention of calcification with TPEN in pericardial bio-prosthetic heart valve material(AVES YAYINCILIK, 2008) Ayaz, Murat[Abstract not Available]Öğe Gender-dependent effects of selenite on the perfused rat heart - A toxicological study(HUMANA PRESS INC, 2007) Ayaz, Murat; Dalkilic, Nizamettin; Bariskaner, Hulagu; Tuncer, Seckin; Demirel, IlhamiGender differences are related to the manner in which the heart responds to chronic and acute stress conditions of physiological and pathological nature. Depending on dose, sodium selenite acts as an antioxidant proven to have beneficial effects in several pathological conditions G. Drasch, J. Schopfer, and G. N. Schrauzer, Selenium/cadmium ratios in human prostates: indicators of prostate cancer risk of smokers and nonsmokers, and relevance to the cancer protective effects of selenium, Biol. Trace Element Res. 103(2), 103-107 (2005); R. G. Kasseroller and G. N. Schrauzer, Treatment of secondary lymphedema of the arm with physical decongestive therapy and sodium selenite: a review, Am. J. Ther. 7(4), 273-279 (2000); G. N. Schrauzer, Anticarcinogenic effects. of selenium, Cell. Mol. Life Sci. 57(13-14),1864-1873 (2000); I. S. Palmer and O. E. Olson, Relative toxicities of selenite and selenate in the drinking water of rats, J. Nutr. 104(3), 306-314 (1974). To date, little is known about the gender-dependent direct effects of toxic doses of selenite on electrophysiology of the cardiovascular system H. A. Schroeder and M. Mitchener, Selenium and tellurium in rats: effect on growth, survival and tumors, J. Nutr. 101(11), 1531-1540 (1971); G. N. Schrauzer, The nutritional significance, metabolism and toxicology of selenomethionine, Adv. Food Nutr. Res. 47, 73-112 (2003). In the present study, the effects of in vitro toxic concentrations of sodium selenite ranging from 10(-6) M to 10(-3) M were tested on both male and female rat heart preparations. The toxic effects seen in an electrocardiogram and left ventricular pressure were dose and sex dependent atÖğe Selenium-induced changes on rat sciatic nerve fibers: Compound action potentials(PROUS SCIENCE, SA-THOMSON REUTERS, 2008) Ayaz, Murat; Dalkilic, Nizamettin; Tuncer, Seckin; Bariskaner, HulaguThe nervous system, through its important role as a communication network, governs reactions to stimuli, processes information and generates elaborate patterns of signals to control complex behaviors. Although selenium (Se) was shown to have some beneficial effects in pathological conditions, it is still a toxic element with a fairly small therapeutic window. In this study, the direct effects of Se ranging from 10(-8) to 10(-4) M were tested on rat sciatic nerve preparations. The toxicity started at 10-8 M and the degree of alterations was found to be dose-dependent. In between the measured parameters, total compound action potential area (Astart 3 70 +/- 0.16 ms x mV and A(-8) M = 3.04 +/- 0.14 ms x mV) and maximum depolarization points (MDstart = 6.70 +/- 0.22 mV and MD(-8) M = 6.04 +/- 0.18 mV) were the first to be affected from 10(-8) M. Latencies and conduction velocity distribution measurements have shown that nerve fibers having intermediate conduction velocities (20-35 m/s) are the first to be affected front this toxicity. Despite the fact that the new claims concluded the positive effects of the administrations, it is evident that the dose of supplementation must be fine-tuned to avoid possible side effects. Copyright 2008 Prous Science, S.A.U. or its licensors. All rights reserved.Öğe Sexual dependency of rat sciatic nerve fiber conduction velocity distributions(TAYLOR & FRANCIS LTD, 2007) Ayaz, Murat; Kiziltan, Erhan; Tuncer, Seckin; Dalkilic, Nizamettin; Demirel, Ilhami; Bariskaner, Hulagu; Pehlivan, FeritGender differences, either with the structural or through with hormones, dictate how the corresponding organ or organ system responses to physiological signals. Current study aims to investigate gender dependent differences in conduction related parameters of rat sciatic nerve. Compound action potentials ( CAP) were recorded via suction electrode whereas the conduction velocity distributions (CVD) were performed using the method known as collision technique in the literature. Studied CAP parameters, namely conduction velocities ( CV), area of the CAPs and time required to reach the maximum depolarization (TP) have been found significantly different for female and male rats. Detailed analyses have shown that sex dependent differences were more remarkable in the right leg responses of female and male rats. Additionally, CVDs indicate that the number of fibers having CVs between 5-30 m/s is much more in male right sciatic nerve trunk when compared to age matched female rats. The present study, for the first time clearly shows that shift in the contribution of nerve fibers to lower CVs is the main causal of the sex dependent differences seen in rat sciatic nerve fibers.Öğe Sodium selenite protects against diabetes-induced alterations in the antioxidant defense system of the liver(WILEY, 2006) Ayaz, Murat; Celik, Handan Ak; Aydin, Hikmet Hakan; Turan, BelmaBackground: Free radical genesis of disorder is one of the major subjects of discussion in the explanation of pathological conditions. In this study, the effects of micro molar quantities of sodium selenite treatment on diabetes-induced alterations in the antioxidant defense system were investigated. Methods: Diabetes was induced by administration of streptozotocin (STZ, 50 mg/kg body weight) and both diabetic and control animals were treated with sodium selenite (5 mu mol/kg/day) for 4 weeks. Results: Our results have shown that induction of diabetes in the liver tissue of animals for 5 weeks resulted in decreased superoxide dismutase (SOD), glutathione reductase (GR) and glutathione peroxidase (GSHPx) activities and concomitantly increased lipid peroxidation (LPO). Conclusion: Sodium selenite treatment of the diabetic rats resulted in almost full restoration of all the parameters mentioned above. Metallothionein, which is known to be one of the major antioxidants and a central protein in heavy metal regulation, is altered by diabetes, and sodium selenite treatment restored this alteration as well. Copyright (c) 2005 John Wiley & Sons, Ltd.
