Person: OKTAY, NİHAL ŞEHKAR
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OKTAY
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NİHAL ŞEHKAR
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Publication Metadata only The effect of a single application of different fluoride varnishes on enamel subsurface lesions in vitro(2022-04-01) ŞEN YAVUZ, BETÜL; YILMAZ, MÜESSER AHU; OKTAY, NİHAL ŞEHKAR; KARGÜL, BETÜL; Yildiz P. K., ŞEN YAVUZ B., YILMAZ M. A., OKTAY N. Ş., KARGÜL B.This in vitro study aimed to evaluate the therapeutic effect of different fluoride ion (F) varnish formulations for controlling the carious development of enamel subsurface lesions and the F release into artificial saliva for 2 hr, 24 hr, 48 hr, and 7 days. Artificial enamel carious lesions were created and divided into 6 groups (5 varnish groups and a control group). Varnishes were applied to enamel specimens and then the specimens were incubated in artificial saliva, with the artificial saliva replenished daily. Varnish was removed and lesions were remineralized in artificial saliva for 24 hr. Surface microhardness was measured three times: (i) initially, (ii) after creating the artificial enamel lesions, and (iii) after applying the varnishes. The F release was analyzed after 2 hr, 24 hr, 48 hr, and 7 days of exposure using an ion-selective electrode. Data were analyzed using a One-way Analysis of Variance with the Tukey-Kramer Multiple Comparisons test and the Kruskal-Wallis test with the Dunns Multiple Comparisons test. The highest percentage surface microhardness recovery was found for the treatment with the MI Varnish. According to the percentage surface microhardness recovery results, a statistically significant difference was found between the varnishes and the control group (p < 0.05 and < 0.001). All varnishes released measurable levels of fluoride ions. However, the release of F was the highest in the MI Varnish group (p < 0.01). Duraphat, Enamel Pro Varnish, and MI Varnish released the most F into artificial saliva. Calcium phosphate-based F varnishes improve the capacity of the enamel surface re -hardening. CPP containing F varnish had the highest release of F as compared to the other F releasing varnishes. Further in vivo investigations are also required to prove the clinical applications of the different ingredients containing varnishes.Publication Metadata only Edaravone ameliorates the adverse effects of valproic acid toxicity in small intestine(SAGE PUBLICATIONS LTD, 2015) YARAT, AYŞEN; Oktay, S.; Alev, B.; Tunali, S.; Emekli-Alturfan, E.; Tunali-Akbay, T.; Koc-Ozturk, L.; Yanardag, R.; Yarat, A.Valproic acid (VPA) is a drug used for the treatment of epilepsy, bipolar psychiatric disorders, and migraine. Previous studies have reported an increased generation of reactive oxygen species and oxidative stress in the toxic mechanism of VPA. Edaravone, a free radical scavenger for clinical use, can quench free radical reaction by trapping a variety of free radical species. In this study, effect of edaravone on some small intestine biochemical parameters in VPA-induced toxicity was investigated. Thirty seven Sprague Dawley female rats were randomly divided into four groups. The groups include control group, edaravone (30 mg(-1) kg(-1) day(-1)) given group, VPA (0.5 g(-1) kg(-1) day(-1)) given group, VPA + edaravone (in same dose) given group. Edaravone and VPA were given intraperitoneally for 7 days. Biochemical parameters such as malondialdehyde, as an index of lipid peroxidation(LPO), sialic acid (SA), glutathione levels and glutathione peroxidase, glutathione-S-transferase, superoxide dismutase, catalase, myeloperoxidase, alkaline phosphatase (ALP), and tissue factor (TF) activities were determined in small intestine samples by colorimetric methods. Decreased small intestine antioxidant enzyme activities, increased LPO and SA levels, and increased activities of ALP and TF were detected in the VPA group. Based on our results edaravone may be suggested to reverse the oxidative stress and inflammation due to VPA-induced small intestine toxicity.Publication Metadata only Is sialic acid a promising marker for periodontal diseases?(WOLTERS KLUWER MEDKNOW PUBLICATIONS, 2020) KURU, LEYLA; Oktay, S.; Bal, O. Ozoner; Kuru, L.; Yarat, A.; Noyan, U.Objective: Periodontal diseases are inflammatory chronic infections. Sialic acid (SA) is an acute phase reactant by itself. The aim of this study is to investigate the relationship between salivary and serum SA levels and clinical parameters in different forms of periodontal diseases. Subject and Methods: Systemically healthy subjects were included in the study; patients with chronic gingivitis (CG) (n = 10), chronic periodontitis (CP) (n = 10), and aggressive periodontitis (AgP) (n = 10), and ten volunteers with healthy periodontium as the control group. Total SA levels were determined by Warren's thiobarbituric acid method in whole saliva, parotis saliva, and serum samples of subjects before and 3 months after nonsurgical periodontal treatment. Full mouth clinical parameters including plaque index, gingival index, probing depth, and bleeding on probing were also recorded. Results: Before treatment, in both periodontitis groups salivary and serum SA levels were higher than those of controls (P = 0.001). Both salivary and serum SA levels decreased significantly in the patient groups after treatment (P < 0.001). Multiple comparisons of baseline clinical parameters in all groups revealed significant differences (P = 0.001) and these parameters decreased significantly on the 90th day (P < 0.01). There were positive correlations between SA levels and periodontal indices of the CG, CP, and AgP groups (P < 0.05). Conclusion: Our results suggest that SA level in both saliva and serum may be a potentially useful marker to determine inflammatory changes and investigate different forms of periodontal diseases.Publication Metadata only Effects of altered thyroid states on oxidative stress parameters in rats(Walter de Gruyter GmbH, 2017) OKTAY, NİHAL ŞEHKAR; Oktay S., Uslu L., Emekli N.Thyroid hormones are effective on oxidant-antioxidant balance by leading basal metabolic rate. In this study, the effects of altered thyroid states on low density lipoprotein (LDL) oxidation and oxidative stress parameters were investigated in an experimental animal model. Thirty female Wistar Albino rats were equally divided into 3 groups as follows: control group; hypothyroid group (methimazole (75 mg/100 g was added to diet); hyperthyroid group [L-thyroxine (0.4 mg/100 g was added to diet)]. Oxidized LDL (ox-LDL) levels, thyroid, and lipid parameters were determined in serum. Also lipid peroxidation (LPO), sialic acid (SA) and glutathione levels (GSH), as well as superoxide dismutase (SOD) and catalase (CAT) activities were determined in tissue samples. A significant increase in lipid parameters was observed in hypothyroid group, whereas these parameters were decreased in hyperthyroid group compared to control group. For ox-LDL levels, a significant increase was observed both in hypothyroid and hyperthyroid groups. In brain, liver and kidney tissues, LPO and SA levels were increased, whereas GSH levels were decreased both in hypothyroid and hyperthyroid groups. The SOD and CAT activities were significantly decreased in hypothyroid group, however, they were increased in hyperthyroid group compared to control group. Both hypothyroid and hyperthyroid conditions modify the oxidant-antioxidant state in serum and tissues. Increased SOD and CAT activities in hyperthyroid group suggest that elevated thyroid hormones can reduce oxidative stress by maintaining antioxidant defense and they might have a protective effect on some tissues against oxidants. © 2017 Walter de Gruyter GmbH, Berlin/Boston.Publication Metadata only Melatonin improves hyperglycemia induced damages in rat brain(WILEY, 2018) YARAT, AYŞEN; Gurel-Gokmen, Begum; Ipekci, Hazal; Oktay, Sehkar; Alev, Burcin; Ustundag, Unsal Veli; Ak, Esin; Akakin, Dilek; Sener, Goksel; Emekli-Alturfan, Ebru; Yarat, Aysen; Tunali-Akbay, TugbaBackground Diabetes mellitus is an endocrine disorder which is characterized by the development of resistance to the cellular activity of insulin or inadequate insulin production. It leads to hyperglycemia, prolonged inflammation, and oxidative stress. Oxidative stress is assumed to play an important role in the development of diabetic complications. Melatonin is the hormone that interacts with insulin in diabetes. Therefore, in this study, the effects of melatonin treatment with or without insulin were examined in diabetic rat brain. Methods Results Rats were divided into five groups as control, diabetes, diabetes + insulin, diabetes + melatonin, and diabetes + melatonin + insulin. Experimental diabetes was induced by streptozotocin (60 mg/kg, i.p.). Twelve weeks after diabetes induction, rats were decapitated. Malondialdehyde, glutathione, sialic acid and nitric oxide levels, superoxide dismutase, catalase, glutathione-S-transferase, myeloperoxidase, and tissue factor activities were determined in brain tissue. Melatonin alone showed its antioxidant effect by increasing brain glutathione level, superoxide dismutase, catalase, and glutathione-S-transferase activities and decreasing malondialdehyde level in experimental diabetes. Although insulin did not have a significant effect on glutathione and glutathione-S-transferase, its effects on lipid peroxidation, superoxide dismutase, and catalase were similar to melatonin; insulin also decreased myolopeoxidase activity and increased tissue factor activity. Combined melatonin and insulin treatment mimicked the effects of insulin. Conclusion Addition of melatonin to the insulin treatment did not change the effects of insulin, but the detailed role of melatonin alone in the treatment of diabetes merits further experimental and clinical investigation.Publication Metadata only A guide to vitamins and their effects on diseases(Cambridge University Press, Cambridge (MA), USA , 2023-01-01) OKTAY, NİHAL ŞEHKAR; Oktay N. Ş.This book provides a contemporary, comprehensive and general review of vitamins and the role of vitamins in diseases. In the first part of the book, readers will be informed about fat-soluble and water-soluble vitamins, vitamin-like substances, how they work in the body, their absorption, storage, transport, their recommended daily allowances, deficiencies and toxicity. In the second part, readers will discover how vitamins affect several diseases, and learn about their mechanism of action in diseases. The second part will also explore vitamin related minerals such as calcium, phosphorus, magnesium, potassium, copper and zinc. The book is unique in that it reveals the mechanism of action of each vitamin in relation to conditions such as the metabolism, autoimmune diseases, degenerative systems, infectious diseases, and aging. This book serves as a brief but beneficial guide for academic institutions, health professionals, practitioners, medical and dentistry students, nutritionists and pharmacists.Publication Metadata only Genetic biomarkers of athletic performance(Nobel Tıp Kitapevleri, 2023-01-01) ULUCAN, KORKUT; TACAL ASLAN, BESTE; OKTAY, NİHAL ŞEHKAR; ULUCAN K., Yılmaz O. O., Eken B. F., POLAT T., Akcagıl Ö., TACAL ASLAN B., OKTAY N. Ş., ÖZKOÇAK G., ŞAKİROĞLU M.Publication Metadata only Overpressure blast injury-induced oxidative stress and neuroinflammation response in rat frontal cortex and cerebellum(ELSEVIER SCIENCE BV, 2018) OKTAY, NİHAL ŞEHKAR; Toklu, Hale Z.; Yang, Zhihui; Oktay, Sehkar; Sakarya, Yasemin; Kirichenko, Nataliya; Matheny, Michael K.; Muller-Delp, Judy; Strang, Kevin; Scarpace, Philip J.; Wang, Kevin K. W.; Tumer, NihalBackground & aim: Overpressure blast-wave induced brain injury (OBI) and its long-term neurological outcome pose significant concerns for military personnel. Our aim is to investigate the mechanism of injury due to OBI. Methods: Rats were divided into 3 groups: (1) Control, (2) OBI (exposed 30 psi peak pressure, 2-2.5 ms), (3) Repeated OBI (r-OBI) (three exposures over one-week period). Lung and brain (cortex and cerebellum) tissues were collected at 24 h post injury. Results: The neurological examination score was worse in OBI and r-OBI (4.2 +/- 0.6 and 3.7 +/- 0.5, respectively) versus controls (0.7 +/- 0.2). A significant positive correlation between lung and brain edema was found. Malondialdehyde (index for lipid peroxidation), significantly increased in OBI and r-OBI groups in cortex (p < 0.05) and cerebellum (p < 0.01-0.001). The glutathione (endogenous antioxidant) level decreased in cortex (p < 0.01) and cerebellum (p < 0.05) of r-OBI group when compared with the controls. Myeloperoxidase activity indicating neutrophil infiltration, was significantly (p < 0.01-0.05) elevated in r-OBI. Additionally, tissue thromboplastin activity, a coagulation marker, was elevated, indicating a tendency to bleed. NGF and NF-kappa B proteins along with Iba-1 and GFAP immunoreactivity significantly augmented in the frontal cortex demonstrating microglial activation. Serum biomarkers of injury, NSE, TNF-alpha and leptin, were also elevated. Conclusion: OBI triggers both inflammation and oxidative injury in the brain. This data in conjunction with our previous observations suggests that OBI triggers a cascade of events beginning with impaired cerebral vascular function leading to ischemia and chronic neurological consequences.Publication Metadata only The effect of vitamin U on the lung tissue of pentyleneterazole-induced seizures in rats(SPRINGER, 2018) YARAT, AYŞEN; Oktay, Sehkar; Bayrak, Gamze; Alev, Burcin; Ipekci, Hazal; Ustundag, Unsal Veli; Turkyilmaz, Ismet Burcu; Pisiriciler, Rabia; Emekli-Alturfan, Ebru; Tunali-Akbay, Tugba; Yanardag, Refiye; Yarat, AysenThe aim of this study is to investigate the therapeutic effects of vitamin U (Vit U) on lung tissue of pentyleneterazole (PTZ)-induced seizures in rats. Sprague Dawley male rats were randomly divided into four groups as follows: control (0.9% NaCl given, intraperitoneally); Vit U (50 mg/kg/day, for 7 days by gavage); PTZ; (60 mg/kg one dose, intraperitoneally); and PTZ + Vit U (in same dose and time). At the end of the experiment, lung tissues were taken and examined biochemically and cytologically. Lipid peroxidation (LPO), glutathione (GSH), sialic acid (SA), and nitric oxide (NO) levels, and superoxide dismutase (SOD) and catalase (CAT) activities were determined in lung homogenates. Imprinted lung samples were stained with May Grunwald-Giemsa stain and microscopically examined for the presence of collagen fibers, macrophage, leucocyte, and epithelial cells. PTZ administration significantly increased GSH level and CAT activity and significantly decreased SOD activity compared to the control group. Vit U administration significantly increased GSH level and CAT activity compared to the control group. GSH and NO levels significantly decreased in PTZ + Vit U group compared to the PTZ group. In cytologic analysis, increased collagen fibers, macrophages, leucocytes, and epithelial cells were observed in PTZ group compared to the control group, and Vit U administration decreased these cytological parameters compared to the PTZ group. The findings of this study support the possible protective role of using Vit U as an add-on therapy in order to prevent lung tissue injury which may occur during seizures in epilepsy.Publication Metadata only The antioxidant and anti-inflammatory efficiency of hyaluronic acid after third molar extraction(CHURCHILL LIVINGSTONE, 2015) YARAT, AYŞEN; Gocmen, Gokhan; Gonul, Onur; Oktay, Nihal Sehkar; Yarat, Aysen; Goker, KamilPurpose: Hyaluronic acid (HA) has a number of clinical applications in current practice. Therefore, correlation of HA with free radicals and inflammatory cells is clinically important. The purpose of this study is to measure the efficacy of high molecular weight HA on the oxidative stress of oral wounds (glutathione (GSH) and lipid peroxidation (LPO) levels), the inflammatory reaction (leucocytes, collagen and angiogenesis content), pain (visual analogue scale (VAS) records) and trismus (maximum interincisal opening (MIO) records) after third molar (M3) extraction. Patients and methods: 40 patients were included in this study. 0.2 ml 0.8% HA was applied immediately after surgery within the HA group (n = 20). Nothing was applied to the control group (n = 20). The primary outcome variables were the changes in the inflammatory reaction (leucocyte, angiogenesis and collagen content), oxidative stress (GSH, LPO) and clinical parameters (VAS, MIO). Results were compared immediately after extraction (TO) and 1 week after surgery (T1). Bivariate analyses were used to assess the differences between the HA and control groups for each study variable. Results: There was a statistically significant difference of leucocyte infiltration and angiogenesis between the groups at T1. The HA group showed less leucocyte infiltration and more angiogenesis than the control group. There was no statistically significant difference in oxidative stress, VAS or MIO levels between the groups. Conclusion: Our results confirm the hypothesis that HA has an anti-inflammatory effect following M3 extraction. However, the oxidative stress levels and clinical outcomes were similar after one week. Further studies examining these parameters at different times are necessary. (C) 2015 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.