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 Metadata only Peripheral nervous system assessment in acromegaly patients under somatostatin analogue therapy(SPRINGER, 2017) YAVUZ, DİLEK; Alibas, H.; Yavuz, D. Gogas; Koytak, P. Kahraman; Uygur, M.; Tanridag, T.; Uluc, K.Purpose Acromegaly is known to affect peripheral nervous system (PNS) causing carpal tunnel syndrome (CTS) and polyneuropathy. The frequency of these disorders and the evaluation methods vary among studies. In the present study, we aimed to examine PNS of acromegaly patients under somatostatin analogue (SSA) therapy. Methods Forty-eight acromegaly patients (26 F/22 M, 45.58 +/- 11.6 years) under SSA treatment and 44 healthy controls (25 F/19 M, 47.46 +/- 8.7 years) were assessed by symptom questionnaires, neurologic examination and electrophysiological studies. Results 87.5 % of the acromegaly patients had at least one abnormal finding regarding PNS. With the incorporation of palm-wrist median nerve conduction velocity method, we detected CTS in 50 % of patients. Polyneuropathy was less frequent (29.2 %). Both conditions were independent from the coexisting diabetes mellitus (p = 0.22 for CTS, p = 0.71 for polyneuropathy). Polyneuropathy but not CTS was more common among biochemically uncontrolled acromegaly patients rather than those under control (p = 0.03; p = 0.68, respectively). Conculsion Our findings emphasize the high prevalence of peripheral nervous system involvement in acromegaly patients under SSA therapy and importance of neurological evaluation of these patients. Early diagnosis and treatment of the disease may reduce the PNS involvement.Publication Metadata only Estrogen receptor gene polymorphisms in a group of postmenopausal Turkish women: association with bone mineral density(TAYLOR & FRANCIS LTD, 2012) YOLDEMİR, AHMET TEVFİK; Yavuz, D. G.; Yoldemir, T.; Ozaltun, K.; Erenus, M.Objective To evaluate the frequency of the estrogen receptor (ER) gene PvuII and XbaI polymorphisms and their associations with bone mineral density (BMD) in a group of postmenopausal Turkish women. Design A total of 125 healthy postmenopausal women and 125 premenopausal healthy young women as controls were included in the study. The PvuII and XbaI polymorphisms in the ER gene were studied by the polymerase chain reaction-restriction fragment length polymorphism method. The BMD of the lumbar vertebrae and femoral neck were measured by dual-energy X-ray absorptiometry. Results The frequencies of the ER alpha PVuII genotypes PP, Pp and pp were 20%, 54.4% and 25.6% in premenopausal and 24.8%, 44.8% and 30.4% in postmenopausal women, respectively. The frequencies of the ER XbaI genotypes XX, Xx, xx were 16.8%, 48.8% and 34.4% in premenopausal and 16.8%, 48% and 35.2% in postmenopausal women, respectively. There was no difference in the frequencies of ER gene polymorphisms between premenopausal and postmenopausal women. BMD measurements were not different between ER PvuII and XbaI genotypes in premenopausal and postmenopausal women. Conclusions ER gene PvuII and XbaI polymorphisms have no major influence on bone mineral density in our group of postmenopausal women.Publication Metadata only Effect of low- and high-dose levothyroxine on thyroid nodule volume: a crossover placebo-controlled trial(BLACKWELL PUBLISHING LTD, 2002) YAVUZ, DİLEK; Koc, M; Ersoz, HO; Akpinar, I; Gogas-Yavuz, D; Deynell, O; Akalin, SOBJECTIVE The efficacy and the effective dose of levothyroxine suppressive therapy in the treatment of benign thyroid nodules are controversial. In this study, we aimed to determine the response of solitary thyroid nodules to low- or high-level TSH suppression in a placebo-controlled, randomized crossover trial. DESIGN Forty-nine patients with solitary thyroid nodules on palpation were randomized to high-level and low- level TSH suppression groups. In each group, patients were further randomized to placebo and active levothyroxine subgroups. Patients in each subgroup were crossed over to placebo or active levothyroxine at the end of the first year and were then followed up for an additional year. METHODS TSH levels were suppressed to 0.4-0.6 mIU/ml and less than or equal to0.01 mIU/ ml in the low-level and high-level TSH suppression groups, respectively. Nodule volumes were measured at baseline and every 6 months after the desired level of TSH was reached if the patients were in the active levothyroxine treatment group or every 6 months if they were in the placebo group. RESULTS In high-level TSH suppression groups, nodule volume decreased significantly at the end of the active treatment periods (4.99 +/- 2.02 ml vs. 3.20 +/- 1.50 ml, P < 0.01, in Group 1; and 3.72 &PLUSMN; 1.79 ml to 2.05 &PLUSMN; 0.64 ml, P < 0.001, in Group 2). In the low-level TSH suppression groups, nodule volume also decreased significantly at the end of the active treatment periods (4.43 +/- 1.76 ml vs. 3.04 +/- 1.32, P < 0.05, in Group 3; and 3.59 &PLUSMN; 0.89 ml to 2.22 &PLUSMN; 0.59 ml, P < 0.01, in Group 4). Nodule volumes regained their original volumes during the placebo treatment periods. The percentage decline in clinically relevant nodule volume reduction (greater than or equal to50%) was similar in the low- level and high-level TSH suppression groups. CONCLUSION Low- and high-level TSH suppression were equally effective in reducing nodule volume and thus, considering the complications of high-level TSH suppression, low- level TSH suppression should be used if one considers levothyroxine suppressive therapy to reduce thyroid nodule size.Publication Metadata only Vitamin D receptor gene BsmI, FokI, ApaI, TaqI polymorphisms and bone mineral density in a group of Turkish type 1 diabetic patients(SPRINGER-VERLAG ITALIA SRL, 2011) YAVUZ, DİLEK; Yavuz, Dilek Gogas; Keskin, Lezan; Kiyici, Sinem; Sert, Murat; Yazici, Dilek; Sahin, Ibrahim; Yuksel, Meral; Deyneli, Oguzhan; Aydin, Hasan; Tuncel, Ercan; Akalin, SemaPrevious studies have suggested an influence of vitamin D receptor alleles on bone metabolism and on susceptibility to type 1 diabetes mellitus in different ethnic populations. We aimed to investigate the distribution of vitamin D receptor (VDR) alleles in relation to biochemical bone turnover parameters and bone densitometry measurements in a group of Turkish type 1 diabetic patients. One hundred and seventeen patients (M/F 57/60, 27.6 +/- A 7.3 y duration of diabetes 8.1 +/- A 6.3 y) and 134 healthy controls (M/F 61/73, 26.2 +/- A 5.3 y) were included in the study. Bone mineral density (BMD) was evaluated by dual-energy X-ray absorptiometry (DEXA). The vitamin D receptor gene (VDR) polymorphisms FokI, Bsm1, Apa1, and Taq1 were examined using a PCR-based restriction analysis. Serum levels of calcium, phosphor osteocalcin, intact parathyroid hormone, and C telopeptide were measured. Vitamin D receptor Bsm1 Fok1, Apa1, and Taq1 genotype distributions were not different between patient with diabetes and control groups. BMD was 0.77 +/- A 0.2 g/cm(2) vs. 0.97 +/- A 0.2 g/cm(2) (P = 0.0001) for the femur, 1.0 +/- A 0.1 g/cm(2) vs. 1.13 +/- A 0.1 g/cm(2) (P = 0.001) for type 1 diabetic patients and controls. Bone turnover markers were significantly lower in type 1 diabetic group. BMD measurements and bone metabolic markers were not different between the genotypes in either the patient with diabetes or the controls. The VDR gene polymorphisms, Bsm1, Fok 1, Apa1, and Taq1 showed no influence on bone metabolism in our group of type 1 diabetic patients.Publication Metadata only Epicardial Fat Tissue Thickness Correlates with Endothelial Dysfunction and Other Cardiovascular Risk Factors in Patients with Metabolic Syndrome(MARY ANN LIEBERT, INC, 2010) YAVUZ, DİLEK; Aydin, Hasan; Toprak, Ahmet; Deyneli, Oguzhan; Yazici, Dilek; Tarcin, Oezlem; Sancak, Seda; Yavuz, Dilek; Akalin, SemaBackground: Epicardial adipose tissue has shown to be related to cardiovascular risk. The aim of this study is to investigate the relationship between epicardial adiposity and endothelial function in metabolic syndrome. Methods: Fifty patients with metabolic syndrome were recruited. Anthropometric measurements, fasting blood glucose, insulin, lipid profile, high-sensitivity C-reactive protein (hsCRP), fibrinogen, apolipoprotein A (Apo A), Apo B1, and lipoprotein (a) [Lp(a)] were determined. Homeostasis model assessment of insulin resistance (HOMA-IR) was calculated. Epicardial fat thickness was measured via two-dimensional M-mode echocardiography. Endothelial function was assessed as flow-mediated dilatation at the brachial artery. Results: Epicardial fat tissue thickness was shown to be correlated negatively with FMD and positively with age, diastolic blood pressure, hsCRP, fibrinogen, HOMA-IR, and lipid parameters. Multiple regression analysis showed epicardial fat tissue thickness to be an independent factor influencing the endothelial function. Conclusions: Epicardial fat tissue may be a useful parameter in the assessment of patients with metabolic syndrome.Publication Metadata only Vitamin D receptor gene polymorphisms in a group of postmenopausal Turkish women: association with bone mineral density(INFORMA HEALTHCARE, 2011) YOLDEMİR, AHMET TEVFİK; Yoldemir, T.; Yavuz, D. G.; Anik, G.; Verimli, N.; Erenus, M.Objective To determine the frequency of the vitamin D receptor (VDR) gene polymorphisms BsmI, ApaI, TaqI and FokI and their associations with bone mineral density (BMD) in postmenopausal Turkish women. Design One hundred and thirty healthy postmenopausal women and 130 premenopausal healthy women acting as controls were included in the study. The BsmI, FokI, ApaI and TaqI polymorphisms in the VDR gene were studied by polymerase chain reaction-restriction fragment length polymorphism method. The BMD of the lumbar vertebrae and femur neck were measured by dual-energy X-ray absorptiometry. Comparisons between the groups were performed using the paired t-test and ANOVA. chi(2) or contingency tables were used to analyze qualitative results. Results Genotypes BB, Bb and bb occurred in premenopausal women with frequencies of 16.92%, 50% and 33.08% and in postmenopausal women with frequencies of 16.92%, 56.15% and 26.92%, respectively. Genotypes FF, Ff, ff occurred in premenopausal women with frequencies of 47.69%, 42.31% and 10% and in postmenopausal women with frequencies of 50.77%, 42.31% and 6.92%, respectively. Genotypes AA, Aa, aa occurred in premenopausal women with frequencies of 23.85%, 56.15% and 20% and in postmenopausal women with frequencies of 26.15%, 46.15% and 27.70%, respectively. Genotypes TT, Tt and tt occurred in premenopausal women with frequencies of 37.69%, 45.38% and 16.92% and in postmenopausal women with frequencies of 39.23%, 45% and 15.38%, respectively. There was no difference in the frequencies of VDR gene polymorphisms between premenopausal and postmenopausal women. BMD measurements were not different between genotypes in premenopausal and postmenopausal women. Conclusions The VDR gene BsmI, FokI, ApaI and TaqI polymorphisms have no major influence on bone mineral density in our group of postmenopausal women.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 Effects of restoration of the euthyroid state on epicardial adipose tissue and carotid intima media thickness in subclinical hypothyroid patients(HUMANA PRESS INC, 2015) ÖZBEN SADIÇ, BESTE; Yazici, Dilek; Ozben, Beste; Toprak, Ahmet; Yavuz, Dilek; Aydin, Hasan; Tarcin, Ozlem; Deyneli, Oguzhan; Akalin, SemaEpicardial adipose tissue (EAT) thickness is a novel cardiovascular risk indicator, whereas carotid intima media thickness (CIMT) is a known marker of subclinical atherosclerosis. The aim of this study was to measure EAT thickness and CIMT in subclinical hypothyroid (SCH) patients and to determine the effect of restoration of the euthyroid state on these variables. The study included 43 patients with SCH (mean age: 35.2 +/- 10.7 years; F-M ratio: 42: 1) and 30 healthy controls (mean age: 34.5 +/- 8.2 years; F-M ratio: 25: 5). EAT thickness and CIMT were measured via conventional echocardiography and ultrasonography. Among the patients, 23 were followed up with L-thyroxine replacement until restoration of the euthyroid state and re-evaluated 6 months after baseline. Basal EAT thickness was higher in the SCH patients than in the controls (3.2 +/- 0.7 vs. 2.3 +/- 0.3 mm-p < 0.0001), whereas CIMT was similar in both groups (0.50 +/- 0.09 vs. 0.48 +/- 0.04 mm). EAT thickness was correlated with CIMT in the patient group (r = 0.39, p = 0.01), but this correlation was not evident based on multivariate analysis when corrected for age and body mass index (r(2) = 0.47 and p = 0.0001 for the model). In the follow-up patient subgroup, both EAT thickness and CIMT decreased significantly following L-thyroxine treatment, when normal TSH levels were attained (3.4 +/- 0.7 vs. 2.3 +/- 0.5 mm-p = 0.007 and 0.51 +/- 0.09 vs. 0.46 +/- 0.07 mm-p = 0.01, respectively). EAT thickness was greater in the SCH patients than in controls, whereas CIMT was similar in both groups. Restoration of the euthyroid state with L-thyroxine treatment was associated with significant decreases in EAT thickness and CIMT in the group of patients that received L-thyroxine treatment and, as such, might reduce the cardiovascular risk associated with SCH.Publication Metadata only Effects of vitamin D supplementation on insulin sensitivity and androgen levels in vitamin-D-deficient polycystic ovary syndrome patients(WILEY, 2018) YOLDEMİR, AHMET TEVFİK; Karadag, Cihan; Yoldemir, Tevfik; Yavuz, Dilek GogasAimThe aim of this study was to identify the effects of vitamin D supplementation on insulin sensitivity and androgen levels in vitamin-D-deficient polycystic ovary syndrome (PCOS) patients. MethodsSixty-seven vitamin-D-deficient (25-hydroxyvitamin D [25(OH)D] levels below 20ng/mL) PCOS patients and 54 vitamin-D-deficient non-PCOS volunteer subjects matched for age and body mass index were enrolled to this prospective study. All participants were given 50000IU/week cholecalciferol orally for 8weeks and 1500IU/day for 4weeks. Insulin sensitivity was calculated with the Matsuda insulin sensitivity index (ISI) based on an oral glucose tolerance test. Matsuda ISI, gonadal hormones (estrogen, testosterone, androstenedione), and 25(OH)D levels were studied before and at the end of the 12th week of vitamin D load. ResultsAfter vitamin D supplementation, serum androstenedione levels had decreased significantly (P=0.007) and Matsuda ISI values had increased significantly (P=0.001) in the PCOS group but no significant changes were seen in those parameters in controls. We observed positive correlations between 25(OH)D levels and Matsuda ISI (r=0.307; P< 0.01), and negative correlations between 25(OH)D levels and total testosterone (r=-0.306; P< 0.01) and androstenedione (r=-0.275; P< 0.01) levels in the PCOS group. ConclusionVitamin D supplementation increased insulin sensitivity and decreased androgen levels in vitamin-D-deficient women with PCOS but did not have any effect in vitamin-D-deficient non-PCOS women. These results may indicate the possible role of vitamin D in the complex pathogenesis of PCOS.