Person: VELİOĞLU ÖĞÜNÇ, AYLİZ
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VELİOĞLU ÖĞÜNÇ
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AYLİZ
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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 Open Access Effects of ACE inhibition and Angiotensin II receptor blockade on glomerular basement membrane protein excretion and charge selectivity in Type 2 diabetic patients(J R A A S LTD, 2006-06) VELİOĞLU ÖĞÜNÇ, AYLİZ; Deyneli, Oguzhan; Yavuz, Dilek; Velioglu, Ayliz; Cacina, Hasan; Aksoy, Nihal; Haklar, Goncaguel; Taga, Yavuz; Akalin, SemaAngiotensin-converting enzyme (ACE) inhibitors may reduce urinary albumin excretion (UAE) by decreasing glomerular pressure and increasing glomerular charge selectivity through preservation of glycosaminoglycans. The effect of Angiotensin II antagonism on glomerular charge selectivity remains to be determined. The aim of this study was to compare the effects of an AT, blocker losartan and an ACE inhibitor (ACE-I) enalapril on UAE, extracellular matrix proteins, glycosaminoglycan excretion(U-GAG) and red blood cell anionic charge (RBCCh) which are the indirect markers of glomerular basement membrane anionic content in hypertensive Type 2 diabetic patients. Twenty-four patients were randomised into two groups and received either enalapril (5-20 mg/d) or losartan (50-100 mg/d). All parameters were measured at baseline and after six months of treatment. At the end of six months, systolic and diastolic blood pressures (BP), UAE rates, U-GAG excretion and RBCCh were significantly and equally reduced in both treatment groups compared with baseline. RBCCh was negatively correlated with UAE (r = -0.57, p < 0.0001) and U-GAG excretion (r = -0.57, p < 0.0001); UAE was correlated with U-GAG excretion (r = 0.58, p < 0.0001). In conclusion, enalapril and losartan treatment were equally effective in reducing BP, UAE as well as U-GAG excretion and preserving RBCCh in hypertensive Type 2 diabetic patients. ACE inhibition and AT(1)-receptor blockade may have favourable effects on preserving glomerular anionic content in hypertensive diabetic patients.Publication Open Access Effects of ACE inhibition and AT(1)-receptor antagonism on endothelial function and insulin sensitivity in essential hypertensive patients(SAGE PUBLICATIONS LTD, 2003-09) VELİOĞLU ÖĞÜNÇ, AYLİZ; Yavuz, D; Koc, M; Toprak, A; Akpinar, I; Velioglu, A; Deyneli, O; Haklar, G; Akalin, SObjective Disturbed endothelial function is closely associated with hyperinsulinaemia and insulin resistance in essential hypertension. The alms of this study were: 1) to evaluate whether the two alternative drugs, angiotensin-converting enzyme (ACE) inhibitors and Angiotensin 11 (Ang 11) antagonists, had comparable effects on glucose metabolism and endothelial function. 2) to determine whether they improve endothelial dysfunction through modulating insulin resistance and oxidative stress. Study design and methods Essential hypertensive patients were randomised into two groups: Twelve (nine patients in final analysis) patients were given enalapril (enalapril group), and twelve (nine patients in final analysis) were given losartan (losartan group). Twelve sex- and age-matched normotensive volunteers were included as controls. Before and after six months of treatment, endothelial function, insulin sensitivity and lipid peroxidation (TBARs) and NO metabolites (NOx) were evaluated. Results Endothelial function, measured as flow mediated dilatation (FMD), was improved in both of the treatment groups (p=0.0001). Calculated insulin sensitivity index also improved in the enalapril-treated group (p=0.05) but not in the losartan-treated group, compared with baseline levels. TBARS values decreased significantly in the enalapril group compared with baseline levels (p<0.001). FMD was positively correlated with insulin sensitivity index (r=0.32, p<0.05) and NOx levels (r=0.39, p=0.01) and negatively correlated with TBARS levels (r=-0.53, p=0.0002) in hypertensive patients. Conclusion Inhibition of the renin-angiotensin system, either with ACE inhibitors or AT(1)-receptor blockers improves endothelial dysfunction. ACE inhibition has prominent effects on improving insulin sensitivity and decreasing oxidative stress in essential hypertensive patients.