Person: YÜKSEL, MERAL
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YÜKSEL
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MERAL
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Publication Open Access Effect of Vitamin D Deficiency and Replacement on Endothelial Function in Asymptomatic Subjects(ENDOCRINE SOC, 2009-10-01) VELİOĞLU ÖĞÜNÇ, AYLİZ; Tarcin, Ozlem; Yavuz, Dilek Gogas; Ozben, Beste; Telli, Ahu; Ogunc, Ayliz Velioglu; Yuksel, Meral; Toprak, Ahmet; Yazici, Dilek; Sancak, Seda; Deyneli, Oguzhan; Akalin, SemaContext: Vitamin D receptors are present in many tissues. Hypovitaminosis D is considered to be a risk factor for atherosclerosis. Objective: This study explores the effects of vitamin D replacement on insulin sensitivity, endothelial function, inflammation, oxidative stress, and leptin in vitamin D-deficient subjects. Design, Setting, and Patients: Twenty-three asymptomatic vitamin D-deficient subjects with 25-hydroxyvitamin D [25(OH)D] levels below 25 nmol/liter were compared with a control group that had a mean 25(OH)D level of 75 nmol/liter. The vitamin D-deficient group received 300,000 IU im monthly for 3 months. The following parameters were evaluated before and after treatment: vitamin D metabolites, leptin, endothelial function by brachial artery flow mediated dilatation (FMD), insulin sensitivity index based on oral glucose tolerance test, and lipid peroxidation as measures of thiobarbituric acid reactive substances (TBARS). Results: FMD measurements were significantly lower in 25(OH)D-deficient subjects than controls (P = 0.001) and improved after replacement therapy (P = 0.002). Posttreatment values of TBARS were significantly lower than pretreatment levels (P < 0.001). A positive correlation between FMD and 25(OH)D (r = 0.45; P = 0.001) and a negative correlation between FMD and TBARS (r = -0.28; P < 0.05) were observed. There was a significant increase in leptin levels after therapy, and the leptin levels were positively correlated with 25(OH)D levels (r = 0.45; P < 0.05). Conclusions: This study shows that 25(OH)D deficiency is associated with endothelial dysfunction and increased lipid peroxidation. Replacement of vitamin D has favorable effects on endothelial function. Vitamin D deficiency can be seen as an independent risk factor of atherosclerosis. Hypovitaminosis D-associated endothelial dysfunction may predispose to higher rates of cardiovascular disease in the winter. (J Clin Endocrinol Metab 94: 4023-4030, 2009)Publication Metadata only The role of cholinergic anti-inflammatory pathway in acetic acid-induced colonic inflammation in the rat(ELSEVIER IRELAND LTD, 2013) VELİOĞLU ÖĞÜNÇ, AYLİZ; Kolgazi, Meltem; Uslu, Unal; Yuksel, Meral; Velioglu-Ogunc, Ayliz; Ercan, Feriha; Alican, InciThe cholinergic anti-inflammatory pathway'' provides neurological modulation of cytokine synthesis to limit the magnitude of the immune response. This study aimed to evaluate the impact of the cholinergic anti-inflammatory pathway on the extent of tissue integrity, oxidant-antioxidant status and neutrophil infiltration to the inflamed organ in a rat model of acetic acid-induced colitis. Colitis was induced by intrarectal administration of 5% acetic acid (1 ml) to Sprague-Dawley rats (200-250 g; n = 7-8 per group). Control group received an equal volume of saline intrarectally. The rats were treated with either nicotine (1 mg/kg/day) or huperzine A (0.1 mg/kg/day) intraperitoneally for 3 days. After decapitation, the distal colon was scored macroscopically and microscopically. Tissue samples were used for the measurement of malondialdehyde (MDA) and glutathione (GSH) levels, and myeloperoxidase (MPO) activity. Formation of reactive oxygen species was monitored by using chemiluminescence (CL). Nuclear factor (NF)-kappa B expression was evaluated in colonic samples via immunohistochemical analysis. Trunk blood was collected for the assessment of tumor necrosis factor (TNF)-alpha, interleukin (IL)-1 beta, IL-10, resistin and visfatin levels. Both nicotine and huperzine A reduced the extent of colonic lesions, increased colonic MDA level, high MPO activity and NF-kappa B expression in the colitis group. Elevation of serum IL-1 beta level due to colitis was also attenuated by both treatments. Additionally, huperzine A was effective to reverse colitis-induced high lucigenin-enhanced CL values and serum TNF-alpha levels. Colitis group revealed decreased serum visfatin levels compared to control group which was completely reversed by nicotine. In conclusion, modulation of the cholinergic system either by nicotine or ACh esterase inhibition improved acetic acid-induced colonic inflammation as confirmed by macroscopic and microscopic examination and biochemical assays. (C) 2013 Elsevier Ireland Ltd. All rights reserved.Publication Open Access Arginase activity and nitric oxide levels in patients with obstructive sleep apnea syndrome(2014-04-02) VELİOĞLU ÖĞÜNÇ, AYLİZ; Yuksel, M; Okur, Hk; Pelin, Z; Ogunc, Av; Ozturk, LPublication Open Access Matrix Metalloproteinase-9 Level and Gene Polymorphism in Sleep Disordered Breathing Patients with or without Cardiovascular Disorders(AVES YAYINCILIK, 2013-03-05) VELİOĞLU ÖĞÜNÇ, AYLİZ; Yuksel, Meral; Kuzu-Okur, Hacer; Velioglu-Ogunc, Ayliz; Pelin, ZerrinObjective: Obstructive sleep apnea syndrome (OSAS) is associated with increased cardiovascular morbidity and mortality. We aimed to investigate the matrix metalloproteinase-9 (MMP-9) level and MMP-9 gene polymorphism in sleep apnea patients with or without cardiovascular disease. Study Design: Case-control study. Material and Methods: Two hundred nine patients [Mean age (+/- SD), 47 (+/- 12) yrs; M/F, 170/39] diagnosed with sleep-disordered breathing were included in the study. Serum MMP-9 level was performed using enzyme-linked immunosorbant assay (ELISA) and MMP-9 gene polymorphism with polymerase chain reaction-restriction fragment length polymorphism. We divided the patient group into two subgroups: (1) patients with confirmed cardiovascular disease, i.e. CV-P Group and (2) patients without cardiovascular disease, CV-N Group. We compared all parameters between the two groups. Results: There were 56 OSAS patients with cardiovascular disorder (CV-positive group) and 153 OSAS patients without cardiovascular disorder (CV-negative group). CC, CT and TT genotype distributions between groups were similar [31 (55%), 25 (45%), 0 (0%) vs 88 (57%), 61 (40%), 4 (3%); respectively, p>0.05]. MMP-9 level was significantly higher in CV-P patients (442.7 +/- 139.3 pg/mL) than in CV-N patients (364.4 +/- 165.0 pg/mL; p=0.0018). Conclusion: Our results showed that the presence of MMP-9 polymorphism was not associated with cardiovascular disease. MMP-9 level was higher in OSAS patients with cardiovascular disorders than without cardiovascular disorders. Finally, MMP-9 genotype was not associated with serum MMP-9 levels.Publication Metadata only The effect of phosphodiesterase-5 inhibition by sildenafil citrate on inflammation and apoptosis in rat experimental colitis(PERGAMON-ELSEVIER SCIENCE LTD, 2011) VELİOĞLU ÖĞÜNÇ, AYLİZ; Karakoyun, Berna; Uslu, Unal; Ercan, Feriha; Aydin, Mehmet Serif; Yuksel, Meral; Ogunc, Ayliz Velioglu; Alican, InciAims: To investigate the effect of sildenafil citrate (SIL) on the extent of tissue integrity, oxidant-antioxidant status and apoptosis in rats with colitis. Main methods: Colitis was induced by trinitrobenzenesulphonic acid (TNBS) in 40% ethanol (30 mg/ml; 0.8 ml) given intrarectally to Sprague-Dawley rats. Sildenafil (25 mg/kg/day) was administered after the induction of colitis and the treatment was continued for 7 days. Other groups received subcutaneously either N(G)-nitro- L-arginine methyl ester (L-NAME; 25 mg/kg) or N(G)-nitro-D-arginine methyl ester (D-NAME; 25 mg/kg) before SIL After decapitation, the distal colon was scored and stored for the measurement of malondialdehyde (MDA) level, glutathione (GSH) content, myeloperoxidase (MPO) activity and apoptosis. Oxidant generation was monitored by using chemiluminescence (CL). Blood was collected for tumor necrosis factor (TNF)-alpha and interleukin (IL)-10 assays. Key findings: The macroscopic lesion score of the colitis group was reduced by SIL (p<0.01) and this effect was abolished by L-NAME (p<0.01). Increase in colonic MDA along with a concomitant decrease in GSH of the colitis group was reversed by SIL (p<0.01 and p<0.001, respectively). L-NAME prevented the effect of SIL on GSH content (p<0.001). Sildenafil also reduced the elevated MPO of the colitis group (p<0.001) and this effect was reversed by L-NAME (p<0.01). Increase in lucigenin CL and serum TNF-alpha levels in the colitis group were also prevented by SIL (p<0.001 and p<0.01, respectively). Significance: Sildenafil is beneficial in TNBS-induced rat colitis partially by nitric oxide-dependent mechanisms via the maintenance of oxidant-antioxidant status, prevention of apoptosis, superoxide production and cytokine release. (C) 2011 Elsevier Inc. All rights reserved.