Person: YAVUZ, DİLEK
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YAVUZ
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DİLEK
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Publication Open Access Erytrocyte membrane anionic charge in type 2 diabetic patients with retinopathy(2004-12) YAVUZ, DİLEK; Budak, Yasemin; Demirci, Hakan; Akdogan, Muberra; Yavuz, DilekPublication 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 aminoguanidine on lipid and protein oxidation in diabetic rat kidneys(2002) YALÇIN, AHMET SUHA; Yavuz D.G., Küçükkaya B., Ersöz H.Ö., Yalçin A.S., Emerk K., Akalin S.Nonenzymatic glycation of tissue and plasma proteins may stimulate the production of oxidant and carbonyl stress in diabetes. The aim of this study was to evaluate the effects of aminoguanidine (AG) on lipid peroxidation, protein oxidation and nitric oxide (NO) release in diabetic rat kidneys. After induction of diabetes with streptozotocin, female Wistar rats were divided into 2 groups. Group DAG (n=9) rats were given AG hydrogen carbonate (1 g/L) in drinking water and group D (n=8) was diabetic control rats given only tap water. Group H (n=8) was followed as healthy controls. At the end of an 8 week period, NO release, lipid and protein oxidation were determined in kidney tissues. NO release was significantly lower in diabetic rats compared with healthy controls (p<0.05). Lipid peroxidation was significantly high in group D (3.9 ± 0.3 nmol MDA/g tissue) compared with the group DAG (2.6 ± 0.1 nmol MDA/g tissue, p<0.01) and group H (2.4 ± 0.2 nmol MDA/g tissue). Protein oxidation was significantly higher in diabetics than healthy controls (563.8 ± 23.9, 655.8 ± 7.2, 431.5 ± 8.8 mmol carbonyl/g tissue for group DAG, D and H, respectively, p< 0.05). A positive correlation between albuminuria and thiobarbituric acid reactive substance (TBARS) levels (r= 0.54, p<0.005) and carbonyl content (r=0.70, p<0.0005) in kidney homogenate were observed. Although AG treatment had no effect on NO release, it significantly decreased lipid peroxidation in diabetic rat cortices. Consequently increased lipid peroxidation -as well as- protein oxidation could be involved in the pathogenesis of diabetic albuminuria.Publication Open Access Endothelial function, insulin sensitivity and inflammatory markers in hyperprolactinemic pre-menopausal women(BIOSCIENTIFICA LTD, 2003-09-01) YAVUZ, DİLEK; Yavuz, D; Deyneli, O; Akpinar, I; Yildiz, E; Gozu, H; Sezgin, O; Haklar, G; Akalin, SBackground: Hyperprolactinemia has been reported to be associated with abnormalities of carbohydrate metabolism. The aim of this study was to evaluate the effects of hyperprolactinemia and bromocriptine (Brc) treatment on endothelial function, insulin sensitivity and inflammatory markers in pre-menopausal women. Methods: Sixteen hyperprolactinemic pre-menopausal women with pituitary adenomas were recruited and 20 healthy subjects were included as controls. Patients were given Brc in doses of 2.5-20 mg/dl until normal levels of prolactin were reached. Prior to treatment and 2 months after prolactin levels were normalized, the following tests were performed. Insulin sensitivity was determined by an oral glucose tolerance test based on a formula named the insulin sensitivity index (ISI composite). Endothelial function was measured as flow-mediated dilatation (FMD) on a brachial artery using high resolution ultrasound. Results: Serum glucose, insulin, estrogen, highly sensitive C-reactive protein (hsCRP), fibrinogen, homocysteine and uric acid levels were measured. Calculated ISI composite and FMD were significantly lower in the hyperprolactinemic group in comparison with the controls and improved after Brc treatment. Serum homocysteine, hsCRP and uric acid levels were significantly higher in hyperprolactinemic patients than in the controls and returned to normal levels with Brc treatment. Serum prolactin concentrations were inversely correlated with FMD measurements (r = - 0.68; P < 0.0001), ISI composite (r = - 0.48; P < 0.005) and serum estrogen (r = - 0.54; P < 0.005), and positively correlated with serum homocysteine concentrations (r = 0.55; P < 0.0001) in the hyperprolactinemic group. Conclusions: The hyperprolactinemic state is associated with impaired endothelial function and decreased insulin sensitivity, which are early markers of atherosclerosis. These alterations may predispose to the development of atherosclerosis in non-treated cases. Correction of the hyperprolactinemic state is associated with improved endothelial function and insulin sensitivity.Publication Open Access A Bibliometric Analysis of Turkey's Contribution to Bone Health Literature from an Endocrinologist Perspective(TURKIYE KLINIKLERI, 2019) YAVUZ, DİLEK; Degertekin, Ceyla Konca; Iyidir, Ozlem Turhan; Yavuz, Dilek GogasObjective: To analyze the trend of Turkish publications related to bone health with respect to global publications and to determine the relative contribution of endocrinologists to metabolic bone disease literature. Material and Methods: Publications related to bone health up to and including the year 2017 were retrieved from the Web of Science (WoS) and TUrkiye Atif Dizini (TAD) database using metabolic bone disease related MeSH terms. Excel (v15.30) and Endnote X8 were used to summarize the bibliometric features, including the number of publications, authors, their affiliations, and contributing countries. Keywords were divided, for a detailed analysis, into three clusters: osteoporosis, parathyroid, and vitamin D-related. Results: A total of 1.880.666 papers were retrieved from WoS globally and, of those, 21.165 (1.13%) were published from Turkey. Of the papers published from Turkey, 3.0% were primarily contributed by endocrinologists. The relative contribution of endocrinology to osteoporosis-related (4.6% vs. 1.5%), parathyroid-related (23.7% vs. 5.3%), and vitamin D-related (23.7% vs. 5.3%) publications was higher for articles originating from Turkey compared to the global data. Endocrinology was among the top five specialties contributing to Turkish metabolic bone disease literature indexed in WoS and TAD. Conclusion: Turkey has a less than expected rate of research output in terms of metabolic bone disease. The relatively higher contribution of endocrinology to that effort is promising. Supporting bone research might accelerate the efforts of Turkish researchers in the field of metabolic bone health.Publication Open Access Vitamin D level is associated with mortality predictors in ventilator-associated pneumonia caused by Acinetobacter baumannii(J INFECTION DEVELOPING COUNTRIES, 2016-06-30) BİLGİLİ, BELİZ; Haliloglu, Murat; Bilgili, Beliz; Haliloglu, Ozlem; Yavuz, Dilek Gogas; Cinel, IsmailIntroduction: Vitamin D plays a role in host defense and is known to be associated with mortality in patients in the intensive care unit (ICU). We aimed to evaluate the relationships between vitamin D levels and predictors of mortality in patients with ventilator-associated pneumonia (VAP) caused by extensively drug-resistant Acinetobacter baumanii (XDR A. baumanii). Methodology: A retrospective single-center study was conducted in an 18-bed adult ICU of a teaching hospital, including all patients with VAP due to XDR A. baumanii. Levels of 25(OH) D, procalcitonin (PCT), C-reactive protein (CRP), n-terminal pro-BNP (NT-proBNP), as well as clinical scores (Sequential Organ Failure Assessment [SOFA], Acute Physiology And Chronic Health Evaluation [APACHE II], Clinical Pulmonary Infection Score [CPIS) were recorded. Results: Forty-for patients were studied over six months. All patients had vitamin D deficiency. The 28-day mortality in patients with 25(OH) D levels <= 10 ng/mL was higher than in patients with 25(OH) D > 10ng/mL (p = 0.001). The fourth-and seventh-day SOFA scores (p=0.04 and p=0.001) and first-and fourth-day procalcitonin levels (p = 0.03 and p = 0.004) were higher in patients with 25(OH) D levels <= 10 ng/mL. The clinical scores (SOFA, CPIS, and CEPPIS) and biomarkers (NT-proBNP, PCT) were negatively correlated with 25(OH) D levels in all study groups. Conclusions: Severe vitamin D deficiency was associated with adverse outcome in VAP due to XDR A. baumanii. Vitamin D levels may be a prognostic predictor of VAP. It is also important to evaluate the effect of rapid vitamin D replacement on mortality.Publication Open Access Out-of-Reference Range Thyroid-Stimulating Hormone Levels in Levothyroxine-Treated Primary Hypothyroid Patients: A Multicenter Observational Study(FRONTIERS MEDIA SA, 2017-09-12) YAVUZ, DİLEK; Yavuz, Dilek Gogas; Yazici, Dilek; Keskin, Lezzan; Atmaca, Aysegul; Sancak, Seda; Sarac, Fulden; Sahin, Ibrahim; Dikbas, Oguz; Hekimsoy, Zeliha; Yalin, Serap; Uygur, Melin; Yilmaz, Murat; Yirmibescik, Sibel; Asmaz, OzlemObjective: Although levothyroxine (LT4) replacement therapy for hypothyroidism has been established as safe, inexpensive and effective, many studies from different countries reported out-of-reference range thyroid-stimulating hormone (TSH) values for the hypothyroid patients under LT4 treatment. The aim of this study was to determine TSH levels of primary hypothyroid patients under LT4 treatment and to assess self-reported compliance with daily LT4 intake in tertiary care centers in Turkey. Design: In this cross-sectional, observational study, adult patients with primary hypothyroidism, receiving LT4 treatment for at least 6 months, were included. The patients were from 12 tertiary care centers in 9 cities of Turkey. TSH and free T4 levels were recorded from patient files and self-reported compliance with daily LT4 intake was assessed by interviewing the subjects at the last visit. Results: A total of 1,755 subjects (46 +/- 13 years; F/M: 89.9/10.1%) with primary hypothyroidism were enrolled. Of the hypothyroid subjects, 44.8% had out-of-reference range serum TSH levels. TSH values were over the reference range (TSH > 4 mIU/L) in 26.2% and were under the reference range (TSH < 0.5 mIU/L) in 18.6% of the patients. Total duration of LT4 treatment was 5.9 +/- 4.7 years and mean dose was 1.2 +/- 0.6 mu g/kg/day. Non-compliant patients (31.1%) had higher TSH levels (6.9 +/- 16 vs 3.8 +/- 0.9 mIU/L, P = 0.01) compared to compliant patients. Conclusion: The results of this study revealed that nearly half of the hypothyroid patients had out-of-reference range serum TSH values, despite under LT4 treatment. Compliance with LT4 treatment seems to be one of the major determinants to reach the target TSH levels in hypothyroid patients.Publication Open Access Use of Biphasic Insulin Aspart 30 in Type 2 Diabetes Treatment: Expert Panel Recommendations(GALENOS YAYINCILIK, 2018) YAVUZ, DİLEK; Akalin, Sema; Aydin, Hasan; Balci, Mustafa Kemal; Comlekci, Abdurrahman; Dinccag, Nevin; Erbas, Tomris; Ersoz, Halil Onder; Yavuz, Dllek Gogas; Gullu, Sevim; Sahin, Ibrahim; Siva, Zeynep Oscar; Unluhizarci, KursadThe goals of Type 2 diabetes treatment are to eliminate the hyperglycemia resulting from insulin insufficiency and/or insulin resistance, delay beta cell damage/depletion, and prevent other metabolic co-morbidities and complications. In the current treatment algorithms, lifestyle changes (medical nutrition therapy, physical exercise) and oral anti-diabetics are followed by insulin therapy, which is considered a replacement therapy for Type 2 diabetes. Pre-mixed insulin preparations, which are an option for patients with poor blood glucose level control under oral anti-diabetics treatment, have been developed to meet both basal and prandial insulin needs by simulating the physiological changes in insulin levels. The consensus on the necessity of individualizing insulin therapy requires physicians to have a detailed knowledge of the various uses of insulin. Therefore, this comprehensive consensus statement has been prepared by a panel of expert endocrinologists from different regions of Turkey to help physicians use biphasic insulin aspart 30 in suitable patients at the right time. In this statement, expert panel opinions on (a) Recommendations for the appropriate initiation, titration, and intensification of insulin treatment, and (b) The treatment algorithms in initiation, titration, and intensification of biphasic insulin aspart 30 treatment and special conditions specific to changing treatment regimen are presented.Publication Open Access Effect of angiotensin-converting enzyme inhibition on endothelial function and insulin sensitivity in hypertensive patients(J R A A S LTD, 2003-06) YAVUZ, DİLEK; Tezcan, H; Yavuz, D; Toprak, A; Akpinar, I; Koc, M; Deyneli, O; Akalin, SIntroduction Evidence suggests an association between insulin resistance, hypertension and impaired endothelial function. Studies have shown that insulin resistance precedes the development of hypertension. By improving insulin sensitivity, it may be possible to improve hypertension and the subsequent damage to vessel walls. Some data indicates beneficial effects of angiotensin-converting enzyme (ACE) inhibitors on insulin sensitivity and endothelial function. We aimed to investigate these effects of ACE inhibition in the same group of patients with essential hypertension. Materials and methods Nine non-smoking, untreated hypertensive patients (38.3+/-9 years, 4/5 male/female) and 12 age-matched healthy subjects (35.2+/-6.7 years, 5/7 male/female) were included in the study. Hypertensive patients were given enalapril maleate (5-40 mg/day) for six months. The following parameters were studied at baseline and at the end of treatment period. Whole body insulin sensitivity was measured by a formula derived from an oral glucose tolerance test and named as the insulin sensitivity index (ISI). Insulin was measured by chemiluminescence and glucose by a glucose oxidase method. Endothelial function was evaluated as flow-mediated dilatation (FMD) of the brachial artery by ultrasonography and expressed as a percentage change relative to baseline diameter. Endothelial-independent vasodilatation was measured after sublingual nitroglycerine. Results FMD was impaired in the hypertensive group compared with healthy subjects (7.3+/-3.1% vs. 15.3+/-4.8%, p<0.0005), and ISI values were 1.18+/-0.6 vs. 4.4+/-0.9 (p<0.0001) respectively. Both insulin sensitivity and FMD improved after the treatment period compared with baseline values, FMD increased from 7.3+/-3.1% to 16.0+/-2.9% (p<0.0005) and ISI from 1.18+/-0.6 to 4.2+/-1.0 (p<0.0001). FMD and ISI showed a significant positive correlation (r=0.67, p<0.001) in the hypertensive group. Conclusions Patients with essential hypertension have impaired endothelial function and decreased whole body insulin sensitivity compared with healthy subjects. Treatment for six months with enalapril maleate seems to improve both FMD and ISI. This Study confirms the beneficial effects of ACE inhibition on both endothelial function and insulin sensitivity tested in the same group of essential hypertensive patients. The mechanism of these favourable effects of ACE inhibition needs to be clarified.