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Dive into the research topics where Guven Ozkaya is active.

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Featured researches published by Guven Ozkaya.


Journal of Endocrinological Investigation | 2010

The effect of vitamin D replacement therapy on insulin resistance and androgen levels in women with polycystic ovary syndrome

Hadi Selimoglu; Cevdet Duran; Sinem Kiyici; Canan Ersoy; Metin Guclu; Guven Ozkaya; Ercan Tuncel; Erdinc Erturk; Sazi Imamoglu

Insulin resistance (IR) is one of the common features of the polycystic ovary syndrome (PCOS), and recent studies indicate the possible role of vitamin D in the pathogenesis of IR and glucose metabolism. Aim of this study was aimed to determine the effect of vitamin D replacement therapy on glucose metabolism, insulin, and androgen levels in obese, insulin-resistant women with PCOS. Eleven women with PCOS were included in the study. Mean age of the patients was 23.6±5.7 yr, body mass index 33.9±5.1 kg/m2. Six patients (54.5%) had acantosis nigricans and 10 (90.9%) oligoamenorrhea. The mean Ferriman Gallwey score was 14.1 ±4.6. Only 2 women were within the normal limits of vitamin D levels as >20 ng/ml. Three weeks after the administration of the single dose of 300,000 units of vitamin D3 orally, 25-hydroxyvitamin D3 significantly increased from 16.9±16 ng/ml to 37.1 ±14.6 ng/ml (p: 0.027) and only 2 women were detected to have vitamin D3 levels <20 ng/ml. Although glucose and insulin levels were decreased non-significantly, homeostasis model assesment (HOMA)-IR significantly decreased from 4.41 ±1.38 to 3.67±1.48 (p: 0.043). No significant alterations were witnessed at the levels of DHEAS, total and free testosterone, androstenedione. No correlation was found between vitamin D with HOMA and other hormonal parameters. In conclusion, women with PCOS have mostly insufficient vitamin D levels, and vitamin D replacement therapy may have a benefical effect on IR in obese women with PCOS.


Progress in Neuro-psychopharmacology & Biological Psychiatry | 2011

Effects of long-term antidepressant treatment on oxidative status in major depressive disorder: A 24-week follow-up study

Vahap Ozan Kotan; Emre Sarandol; Emine Kırhan; Guven Ozkaya; Selcuk Kirli

PURPOSE Major depressive disorder (MDD) is a devastating disease that afflicts large populations and has also been accepted to be an independent risk factor for cardiovascular disease (CVD). Oxidative stress seems to play an essential role in the relationship of MDD and CVD. We aimed to determine the level of oxidative stress in patients with MDD and to investigate the effects of long-term antidepressant (AD) treatment on the oxidative-antioxidative system parameters and CVD risk factors. METHOD Fifty patients who fully met the fourth Diagnostic and Statistical Manual of Mental Disorders criteria for MDD and 44 healthy control subjects were included in the study. Control visits of the patients were repeated 6weeks, 12weeks and 24weeks after beginning of the AD treatment. Lipid profiles, oxidation and oxidizability of apolipoprotein B-containing lipoproteins (expressed as apo B-b-MDA and apo B-Δ-MDA, respectively), levels of plasma malondialdehyde (p-MDA), total antioxidative capacity (TAOC), antioxidant molecules and antioxidant enzyme activities including paraoxonase/arylesterase, red blood cell superoxide dismutase (RBC-SOD) and glutathione peroxidase were determined during 24-week of follow-up period. RESULTS According to the results of the study, p-MDA, apo B-b-MDA and RBC-SOD activity were increased and arylesterase activity was decreased in MDD patients. Body mass index (BMI), vitamin A and total cholesterol levels in MDD patients increased after 24-weeks of AD treatment. RBC-SOD activity, TAOC, p-MDA and apo B-b-MDA levels were decreased; paraoxonase/arylesterase activities and apo B-Δ-MDA were increased at the end of 24th week. CONCLUSION Oxidative stress, demonstrated in MDD patients, was partly improved during 24weeks of AD treatment. Increase in paraoxonase/arylesterase activities and decrease in p-MDA and apo B-b-MDA levels after 24weeks seem to be beneficial for reduction of CVD risk in MDD patients. However increased BMI and apo B-Δ-MDA levels are negative cardiovascular effects of long-term AD treatment.


Mycoses | 2008

Nosocomial candidaemia in children: results of a 9‐year study

Solmaz Celebi; Mustafa Hacimustafaoglu; Özlem Özdemir; Guven Ozkaya

The aim of this study was to determine changes in the incidence of nosocomial candidaemia and to evaluate the risk factors, demographic features, treatment and clinical outcome associated with candidaemia in a Turkish tertiary care paediatric unit within a 9‐year period. The data of children who were diagnosed as nosocomial candidaemia, were examined in this study. Between January 1997 and December 2005, a total of 102 nosocomial candidaemia episodes were identified in 102 patients. The rate of nosocomial candidaemia in our clinic increased from 3.2 cases per 1000 admissions in 1997–1999, to 5.5 per 1000 admissions in 2000–2002 and to 6.9 per 1000 admissions in 2003–2005 (P = 0.003). The species most frequently causing candidaemia were Candida albicans (39.2%), Candida parapsilosis (21.6%) and Candida tropicalis (15.7%). The mortality of C. albicans (37.5%), was significantly higher than the mortality of non‐albicans species (17.7%) (P = 0.04). Independent risk factors associated with candidaemia‐related deaths by logistic regression analysis were disseminated candidiasis (odds ratio, 5.7; P = 0.01), paediatric intensive care unit stay (odds ratio, 8.1; P = 0.001), prolonged antibiotics therapy (odds ratio, 5.2; P = 0.014), use of total parenteral nutrition (odds ratio, 4.4; P = 0.038) and mechanical ventilation (odds ratio, 4.9; P = 0.01). The rate of nosocomial candidaemia in our clinic increased >2‐fold during the study period.


Therapeutic Advances in Psychopharmacology | 2012

Serum brain-derived neurotrophic factor, vascular endothelial growth factor and leptin levels in patients with a diagnosis of severe major depressive disorder with melancholic features

Zeynep Kotan; Emre Sarandol; Emine Kırhan; Guven Ozkaya; SelcÇuk Kırlı

Objective: Brain-derived neurotrophic factor (BDNF), vascular endothelial growth factor (VEGF) and leptin have been hypothesized to be involved in the neurobiology of depression. The aim of this study was to investigate BDNF, VEGF and leptin levels in patients with severe melancholic depression. Methods: A total of 40 drug-free patients with major depressive disorder (MDD) with melancholic features and 40 healthy controls were included in the study. Demographic information, psychiatric evaluation and physical examination were documented for both groups. Serum BDNF, VEGF levels were determined by enzyme-linked immunosorbent assay and leptin with radioimmunoassay methods. The Hamilton Depression Rating Scale and Hamilton Anxiety Rating Scale were applied to the patients. Results: There were no significant differences in serum BDNF, VEGF and leptin levels between the patient and control groups. There was a negative correlation between BDNF levels and the number of depressive episodes. It was noted that VEGF levels decreased with increasing severity of depression. Conclusions: These findings suggest that BDNF levels might be associated with the recurrence of depression and VEGF levels might be a determinant of the severity of depression.


Journal of International Medical Research | 2011

Prevalence of Femoroacetabular Impingement in Asymptomatic Contralateral Hips in Patients with Unilateral Idiopathic Osteoarthritis

N Şahin; Teoman Atici; A Öztürk; Guven Ozkaya; Y Özkan; B Avcu

Radiographic findings of femoroacetabular impingement in the contralateral asymptomatic hip of patients who had undergone total hip arthroplasty because of primary osteoarthritis (n = 44) were compared with controls (n = 40). The centre—edge angle and caput—collum– diaphyseal angle were measured and the presence of crossover sign and a prominent ischial spine noted on anteroposterior radiographs of the pelvis. The α-angle and offset ratio were measured on cross-table lateral radiographs of the hip. The centre—edge angle and offset ratio were significantly lower and the α-angle significantly higher in the study group compared with controls. While the number of cases with an abnormal centre—edge angle was similar in both groups, the numbers with an α-angle > 50° and the number with an offset ratio ≤ 15 were significantly higher in the study group. It was concluded that morphological anomalies associated with femoroacetabular impingement are seen more frequently in the asymptomatic contralateral hip of patients who have undergone hip replacement for primary osteoarthritis than in controls.


Medical Science Monitor | 2016

Catheter-Directed Therapy in Acute Pulmonary Embolism with Right Ventricular Dysfunction: A Promising Modality to Provide Early Hemodynamic Recovery

Asli Gorek Dilektasli; Ezgi Demirdogen Cetinoglu; Nilufer Aylin Acet; Cuneyt Erdogan; Ahmet Ursavas; Guven Ozkaya; Funda Coskun; Mehmet Karadag; Ercüment Ege

Background Catheter-directed therapy (CDT) for pulmonary embolism (PE) is considered as an alternative to systemic thrombolysis (ST) in patients with hemodynamically unstable acute PE who are considered at high bleeding risk for ST. We aimed to evaluate the efficacy and safety of CDT in the management of acute PE with right ventricular dysfunction (RVD). The primary outcomes were mortality, clinical success, and complications. Secondary outcomes were change in hemodynamic parameters in the first 24 hours following the procedure. Material/Methods Medical records of consecutive patients diagnosed as having acute massive or submassive PE with accompanying RVD treated by immediate CDT at our institution from January 2007 to January 2014 were reviewed. Patient characteristics, mortality, achievement of clinical success, and minor and major bleeding complications were analyzed in the overall study group, as well as massive vs. submassive PE subgroups. Change in hemodynamic parameters in the second, eighth, and 24th hours after the CDT procedure were also analyzed. Results The study included 15 consecutive patients (M/F=10/5) with a mean age of 54.2±16.6 years who underwent immediate CDT. Nine of the patients had submassive PE, and 6 had massive PE. In-hospital mortality rate was 13.3% (95% CI, 0.04–0.38). One major, but not life-threatening, bleeding episode was evident in the whole group. Hemodynamic parameters were stabilized and clinical success was achieved in 14/15 (93.3%; 95% CI, 70.2–98.8) of the patients in the first 24 hours. Notably, the hemodynamic recovery was significantly evident in the first 8 hours after the procedure. Conclusions CDT is a promising treatment option for patients with acute PE with RVD with no fatal bleeding complication. In experienced centers, CDT should be considered as a first-line treatment for patients with acute PE and RVD and contraindications for ST, with the advantage of providing early hemodynamic recovery.


Therapeutic Advances in Psychopharmacology | 2011

Metabolic, endocrinologic and cardiac effects of amisulpride: a 24-week follow-up study

Zeynep Kotan; Berrin Ertepe; Cengiz Akkaya; Emre Sarandol; Guven Ozkaya; Selcuk Kirli

Background: Amisulpride is a second-generation antipsychotic which has been proved to be effective in the control of both positive and negative symptoms of schizophrenia. In this study we aimed to determine metabolic, endocrinologic and cardiac effects of amisulpride commonly used in our clinical practice. Methods: A total of 18 patients (11 males, 7 females) diagnosed with schizophrenia received amisulpride at the dosage of 800 mg/day and were followed up for 24 weeks. Positive and negative psychotic symptoms, extrapyramidal and sexual side effects, metabolic, endocrinologic and cardiac parameters were evaluated at regular intervals. Results: Significant improvement in both positive and negative symptoms was observed in patients starting from the second week of treatment. Prolactin levels increased significantly both in men and women starting from the measurement on day 4. Prolactin elevation was significantly higher in women than in men. Increase in total cholesterol level became significant at week 24. No other significant difference was observed between weeks 1 and 24 regarding the other parameters. Conclusions: The clinical data from the present study supports the fact that amisulpride is an effective and safe antipsychotic drug, but elevates prolactin levels in both sexes.


Anatomical Science International | 2009

Statistical shape analysis of the rat hippocampus in epilepsy

Fusun Sonat; Ilker Ercan; Senem Turan Ozdemir; Guven Ozkaya; Behzat Noyan

In this study, we aimed to (1) propose landmarks for the hippocampus in a rat brain using an experimental study and (2) investigate hippocampus shape changes in a rat brain with epilepsy using the statistical shape analysis method. We have used the statistical shape analysis method to illustrate hippocampal shape deformation due to epilepsy. Statistical shape analysis is of increasing interest to the neuroimaging community because of its potential for locating morphological changes. Nineteen rat brains (ten healthy and nine epileptic) with hematoxylin and eosin images of the hippocampus were used. The results strongly indicated that the normalized hippocampal shape of the epileptic group was different from the nonepileptic group; deformation was seen most significantly in the medial regions of the cornu ammonis (CA1 and CA3) of the hippocampus. In conclusion, our landmark-based methodology detected regional differences in the hippocampus in epilepsy. This study may serve as an initial reference for future studies on shape alteration of the hippocampus associated with certain medical conditions.


International Journal of Ophthalmology | 2013

Ultrasound biomicroscopic evaluation of anterior segment cysts as a risk factor for ocular hypertension and closure angle glaucoma

Abdurrahim Dusak; Mehmet Baykara; Guven Ozkaya; Cuneyt Erdogan; Hikmet Özçetin; Ercan Tuncel

AIM To investigate the relationship between the ultrasound biomicroscopic (UBM) features of anterior-segment cysts (ASCs) and increased intraocular pressure (IOP) as a risk factor for closed-angle glaucoma (CAG). METHODS Totally 24 eyes with recently diagnosed ASCs were divided into two groups. First group with ASC and ocular normotension (n=13), second group with ASC and ocular hypertension (n=11). An ophthalmologic examination, including tonometry, slit-lamp biomicroscopy (SLBM), gonioscopy, fundoscopy, pentacam, and UBM, was performed. The features of the ASCs were compared with the IOP. RESULTS ASCs were accurately diagnosed and delineated in 24 eyes using UBM. IOP was elevated in those ASCs with a secondary aetiology (P=0.027), iridociliary location (P=0.006), deformed shape (P=0.013), increased size (P=0.001) and elongated pupillary aperture (P=0.009). However, the count (P=0.343) of ASCs, anterior chamber depth (ACD; P=0.22) and axial lenght (AL; P=0.31) were not associated with ocular hypertension. Correlations were found between the IOP and ASC size (r=-0.712; P=0.003), anterior chamber angle (ACA; r=-0.985; P<0.001), angle opening area (AOA; r=0.885; P<0.001), angulation of iris (r=-0.776, P<0.001), and affected iris quadrant (r =-0.655, P=0.002). CONCLUSION Ocular hypertension in some eyes with ASC might be associated with various mechanisms, including secondary aetiology, iridociliary location, deformed shape, increased size and elongated pupill, which can be determined by UBM.


The Eurasian Journal of Medicine | 2018

Tibial Tuberosity–Trochlear Groove Distance Shows no Change in Patients with or Without Knee Osteoarthritis

Namik Sahin; Teoman Atici; Guven Ozkaya

Objective The primary aim of this study is to compare tibial tuberosity-trochlear groove (TTTG) distance in patients with or without knee osteoarthritis. Additionally, the variability of tibial tubercle according to trochlear groove was evaluated. Materials and Methods In this retrospective cohort study, TTTG distance was measured with two different methods on magnetic resonance (MR) images. TTTG distance was measured by the familiar method on 173 MR images, and by the novel method on 157 MR images of 175 patients totally. The patients were divided into two groups as group 1 (Kellgren Lawrence osteoarthritis grade <2) and group 2 (Kellgren Lawrence osteoarthritis grade ≥2). TTTG values measured by both methods were compared between groups. The coefficient of variation for all patients in TTTG values were calculated. A p-value <0.05 was considered as significant. Results The mean age, sex distributions, and side ratios were different between groups. There was no statistical difference in TTTG values between group 1 and 2. There was no statistically significant difference between the two measurement methods. The coefficient of variation for all patients in TTTG values were high (43.95% for familiar method and 44.64% for novel method). There was excellent interrater reliability for two measurement methods in both groups. Conclusion The TTTG distance is similar in patients with/without knee osteoarthritis. The position of the tibial tubercle according to the trochlear groove is variable, so the tibial tubercle may not be a good reference point for rotational position of the tibial component in total knee arthroplasty.

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