Publications by authors named "Ilhan Tarkun"

Type 2 diabetes mellitus (T2DM) related bone fracture. The effects of glucagon-like peptide-1 receptor analogs for the treatment of T2DM on bone are controversial in human studies. This study aimed to compare the effects of GLP-1 receptor analogs exenatide and insulin glargine treatment on bone turnover marker levels and bone mineral density (BMD) in postmenopausal female patients with T2DM.

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Aromatase enzyme plays an essential role in estrogen-induced tumorigenesis. It is expressed in the normal pituitary and more significantly in prolactinoma tissues. The aim of this study was to investigate the effects of an aromatase inhibitor, letrozole, on MMQ and GH3 rat prolactinoma cell lines and evaluate the possible mechanism of action.

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The levothyroxine absorption test for the assessment of pseudo-malabsorption in patients with refractory hypothyroidism has not been standardised. The aim of this observational study was to describe a protocol for levothyroxine (LT-4) absorption test in patients with refractory hypothyroidism, to report possible side effects and to emphasise the importance of pseudo-malabsorption in the differential diagnosis. The results of 10 patients, who underwent LT-4 absorption tests because thyroid stimulating hormone suppression could not be achieved despite the need for LT-4 >3 mcg/kg/day, were retrospectively analysed.

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Purpose: In our study, it was aimed to evaluate the awareness of diabetic patients about vaccination status and vaccines.

Methods: This cross-sectional study was conducted between January 2019 and February 2019. A survey questioning the level of knowledge about and vaccination status for influenza and pneumonia vaccines was applied by face-to-face interviews with patients with diabetes mellitus who admitted to the diabetes outpatient clinic.

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Graves' disease (GD) and toxic multinodular goitre (TMNG) are the most common thyroid diseases which mainly lead to thyrotoxicosis, however, the underlying mechanism of distinct clinical presentations remains unclear. Protein extracts from the thyroid tissue specimens of the patients with GD and TMNG were subjected to Difference Gel Electrophoresis (DIGE). Differentially regulated protein spots were determined by image analysis, and the spots displaying statistically significant differences were identified by Matrix-Assisted Laser Desorption Ionization Time of Flight Mass Spectrometer (MALDI-TOF) followed by MASCOT search.

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Background: The coexistence of two morphologically different tumors attached to each other creates a very rare type of tumor called a collision tumor. Collision tumors containing pituitary adenoma-sellar meningioma have only been described in four cases to date; we discuss a fifth case harboring a collision tumor comprising a pituitary corticotroph adenoma and a sellar meningioma in the same anatomic position.

Case Presentation: A 34-year-old Caucasian woman presented with menstrual irregularity, severe weakness of the proximal muscles, and 10-15 kg weight gain within a year.

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Papillary thyroid carcinoma (PTC) is the most common type of thyroid cancer (TC). In a subgroup of patients with PTC, the disease progresses to an invasive stage or in some cases to distant organ metastasis. At present, there is an unmet clinical and diagnostic need for early identification of patients with PTC who are at risk of disease progression or metastasis.

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Objectives: Pituicytomas are rare, solid, well-circumscribed, low grade (grade I), non-neuroendocrine, and noninfiltrative tumors of the neurohypophysis or infundibulum, which appear in the sellar/suprasellar regions. Herein, we present a case with Cushing's disease (CD) caused by an ACTH-secreting pituitary adenoma in association with an infundibular pituicytoma. Subject and Results.

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Background: Papillary thyroid carcinoma is the most common endocrine malignancy. Distant metastasis from differentiated thyroid carcinoma is infrequent and the metastasis rate of papillary thyroid carcinoma is lower than that of follicular thyroid carcinoma. Distant metastases from differentiated thyroid carcinoma are usually seen in the lungs and bones; however, renal metastasis is very rare.

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Purpose: Somatostatin analogues (SSAs) can slow down the growth of neuroendocrine tumors. However, the mechanism remains unclear. Recent studies on patients with acromegaly suggest that SSAs may induce apoptosis, increase autophagy, and decrease cell proliferation of pituitary adenoma.

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Purpose: Cushing's syndrome (CS) is a rare disease having diagnostic difficulties. Many diagnostic tests have been defined but none of these are diagnostic alone. Determination of the cause is another problem which sometimes requires more sophisticated and invasive procedures.

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Background/aim: The DAWN2 (Diabetes Attitudes, Wishes, and Needs) study was conducted in order to ascertain the wishes, needs, and attitudes of diabetes patients, their relatives, and healthcare professionals. The study was conducted across 17 countries, including Turkey, and its objective was to introduce policies that could successfully meet these requirements. In this article, the needs, wishes, and attitudes of diabetes patients and their relatives in Turkey are compared with those from other countries.

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Purpose: During follow-up of acromegaly patients, there is a discordance rate of 30% between the measurements of growth hormone and insulin-like growth factor-1 levels. Further tests are required to determine disease activity in patients with discordant results. This study was planned to investigate an association of serum levels of matrix metalloproteinase-2, matrix metalloproteinase-9, and cathepsin B with disease activity in acromegaly patients.

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The incidence of thyroid cancer has been greatly increasing. Several studies aimed to investigate biomarkers for prediction of thyroid cancer. Some of these studies have suggested that thyroid autoantibodies (TAb) could be used as predictors of thyroid cancer risk, but the correlation between TAb and PTC is still a matter of debate.

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Aim: We hypothesized that the estimated risk of malignancy for atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS) is higher than anticipated in Bethesda system. Therefore, we analyzed the actual malignancy risk of repeated AUS/FLUS diagnosis of thyroid fine-needle aspiration biopsies (FNAB).

Materials & Methods: We reported retrospective analyzes of 112 cases with repeated AUS/FLUS diagnosis among 10,769 thyroid FNABs.

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Exposure to high levels of endogenous or exogenous glucocorticoids suppresses the inflammatory response genes. Excessive endogenous hypercortisolism may mask the active inflammatory diseases. Rebound immune modulation may occur after Cushing's syndrome (CS) remission, leading to the new onset of autoimmune diseases.

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Aims: To demonstrate the efficacy of exenatide versus insulin glargine on endothelial functions and cardiovascular risk markers.

Methods: Thirty-four insulin and incretin-naive patients with type 2 diabetes mellitus (body mass index 25-45 kg/m(2)) who received metformin for at least two months were randomized to exenatide or insulin glargine treatment arms and followed-up for 26 weeks. Measurements of endothelial functions were done by ultrasonography, cardiovascular risk markers by serum enzyme-linked immunosorbent assay, and total body fat mass by bioimpedance.

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Papillary thyroid carcinoma (PTC) and medullary thyroid carcinoma (MTC) are two distinct types of thyroid carcinoma with considerable difference in terms of cellular origin, histopathological appearance, clinical course and prevalence. The histogenetic origin and possible molecular mechanisms responsible for the development of mixed medullary-papillary carcinoma of the thyroid are still unclear. The most widely accepted hypotheses considering co-occurrence of MTC and PTC are stem cell theory, collision effect theory and hostage theory.

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The purpose of this study was to evaluate aromatase enzyme expression in growth hormone (GH) secreting adenomas and comparison with prolactinomas, nonfunctional adenomas, and normal pituitary tissues. Also the impact of its expression on clinical and prognostic features was evaluated. 38 acromegaly, 26 prolactinoma, and 31 nonfunctional pituitary adenoma and 11 normal pituitary gland samples from autopsies were included.

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Background: Comorbid neurobehavioral disturbances and type-2 diabetes mellitus (T2DM) warrant immediate research attention. Exenatide, which is a potent and selective agonist for the glucagon-like peptide-1 (GLP-1), is used in the treatment of T2DM. Exenatide displays a multitude of effects in the central nervous system.

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The relationship between subclinical hypothyroidism (SH) and cardiovascular disease has been one of the most popular topics recently. There is still some controversy concerning its cardiovascular impact and management protocols. Our study aims to investigate the presence of the well known preceding clinical situations of atherosclerosis like endothelial dysfunction and inflammation in subclinical hypothyroidism.

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Background: Adipose tissue synthesizes various adipokines such as resistin, adiponectin and visfatin, which have an effect on insulin resistance. This study was designed to show the effect of metformin, one of the most important drugs used to reduce insulin resistance in patients with polycystic ovary syndrome (PCOS), on these adipokines.

Methods: The study group consisted of 24 women with PCOS and 25 healthy, age- and weight-matched, normally menstruating women.

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Objective: The aim of this study is to compare the serum level of visfatin between patients with polycystic ovary syndrome (PCOS) and control subjects matched for age and body mass index (BMI) and to assess the possible correlations of visfatin to the hormonal and metabolic parameters of the syndrome.

Material And Method: Fifty-five patients with PCOS diagnosis composed of 25 obese, 13 overweight, 17 normal weight subjects and 49 women without concomitant disease matched for age and BMI were included in this study.

Results: Serum visfatin levels were similar in normal weight PCOS and control group.

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Background: Insulin resistance is a common finding in both obese and lean women with polycystic ovary syndrome (PCOS). Factors contributing to insulin resistance are still controversial. The purpose of the study was to compare the tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) concentrations in normal weight women with PCOS and a weightmatched healthy control group, and also to evaluate the role of these cytokines in the pathogenesis of insulin resistance.

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