Network


Latest external collaboration on country level. Dive into details by clicking on the dots.

Hotspot


Dive into the research topics where Yavuz Tekelioglu is active.

Publication


Featured researches published by Yavuz Tekelioglu.


American Journal of Hematology | 1999

Apoptotic effects of heparin on lymphoblasts, neutrophils, and mononuclear cells: results of a preliminary in vitro study.

Erol Erduran; Yavuz Tekelioglu; Yusuf Gedik; Alişan Yildiran

In this study the apoptotic effects of heparin on lymphoblasts, neutrophils, and mononuclear cells were evaluated by flow cytometry for detection of sub‐G1 peak, in vitro. Ten children with acute lymphoblastic leukemia (ALL) at diagnosis (Group I), six children with ALL at relapse (Group II), and 10 healthy children (controls) were included in this study. Lymphoblasts in ALL patients, and neutrophils and mononuclear cells in controls, were incubated in increasing heparin concentrations (0, 5, 10, 20 U/ml). Flow cytometric analyses were performed at 0, 1, and 2 hours of incubation in heparin for determination of the apoptotic effects of heparin. In Group I apoptosis was detected in all different levels of heparin concentration except 0 U/ml at 0, 1, and 2 hours. The apoptotic effects of heparin on blast cells peaked at the first hour in 5‐, 10‐, and 20‐U/ml heparin concentrations (p < 0.0001). In Group II similar findings were observed only at zero hour and apoptosis was higher than those in Group I except in 5‐U/ml heparin concentration (p < 0.001). Apoptosis was found to increase with heparin levels in both groups (p < 0.02). In the control group, apoptosis was detected only at the 20‐U/ml heparin concentration and only at the first and second hours. Lymphoblasts are more sensitive to apoptotic effects of heparin than either neutrophils and mononuclear cells (p < 0.004). It can be suggested that low‐dose heparin may cause significant apoptosis of lymphoblasts while inducing no apoptosis on neutrophils and mononuclear cells. The findings of this preliminary study indicate that further and more comprehensive research on the apoptotic effect of heparin on lymphoblasts should be done. Am. J. Hematol. 61:90–93, 1999.


Progress in Neuro-psychopharmacology & Biological Psychiatry | 2003

The influence of olanzapine on immune cells in patients with schizophrenia

Mustafa Bilici; Yavuz Tekelioglu; Saniye Efendioğlu; Ercument Ovali; Metin Ülgen

In vitro and preclinical studies show that biochemical and behavioral effects of olanzapine are quite similar to those of clozapine. In recent years, some cases of reported agranulocytosis due to olanzapine have been published. However, none of these studies compared the hematological and immune parameters before and after treatment. The present study is aimed at investigating the influence of olanzapine on the immune cell parameters by comparing these before and in the third month of olanzapine treatment in patients of schizophrenia. Twenty patients who were diagnosed as schizophrenic depending on the DSM-IV diagnostic criteria were included in the study. The immune parameters of patients were compared by measuring them before the treatment and 3 months after treatment. Immune parameters were analyzed by using flow-cytometry equipment labeled Coulter Epics Elite ESP. The positivity of cell-surface antibody was evaluated as percentage. The rates of CD8 in the third month of the treatment were considerably increased relative to pretreatment. Furthermore, rates of CD4/CD8 were significantly decreased in the third month of the treatment relative to before treatment. These findings suggest that immune impairment may occur during olanzapine treatment in patients with schizophrenia.


Ophthalmic Research | 1998

Analysis of Tears in Patients with Atopic Keratoconjunctivitis, Using Flow Cytometry

Avni Murat Avunduk; Mustafa Cihat Avunduk; Yavuz Tekelioglu

Atopic keratoconjunctivitis (AKC) is a chronic allergic eye disease. Although the pathogenesis is not fully understood, some impairment in cell-mediated immunity was suggested by histopathological findings in conjunctival specimens obtained from affected individuals. T-cell infiltration and an enhanced T-helper/T-suppressor cell ratio in conjunctival biopsy specimens were observed previously by immunofluorescence procedures. We analyzed the cells in tears of patients with AKC using flow cytometry (FCM) and compared the results to those of normal subjects to identify the role of T lymphocytes in the pathogenesis of the disease. The tear samples of the patients and normal subjects were collected with capillary tubes, and the surface receptors of cells were detected with FCM. Statistical analyses were performed with Student’s t test. The percentages of T cells, activated B cells, and T-helper/T-suppressor cell ratios were found to be higher in the tears of patients with AKC than in controls. We propose that a decreased T-suppressor cell concentration in tears may enhance immunoglobulin-E production of B cells, and the signs and symptoms are provoked by inflammatory mediators liberated from mast cell degranulation.


Ophthalmologica | 2006

Flow Cytometrical Analysis of Adhesion Molecules, T-Lymphocyte Subpopulations and Inflammatory Markers in Pterygium

Yavuz Tekelioglu; Adem Türk; Avni Murat Avunduk; Esin Yulug

Background/Aim: Pterygium is a relatively frequent ocular surface disease with an unexplained etiopathogenesis. Our study was carried out with the aim to identify the presence of inflammatory cells and mediators such as T-lymphocyte subgroups (CD4 and CD8), intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1) and human leukocyte antigen-DR (HLA-DR) in pterygium tissue. Methods: Pterygium tissue, obtained from 24 patients, and normal conjunctival tissue, from the nasal bulbar conjunctiva obtained from 14 patients operated for ocular perforations or vitrectomy, were separated into epithelial and stromal components under the microscope and suspended with phosphate-buffered saline solution to form a suspension. Cell suspensions were treated with specific antibodies for ICAM-1, VCAM-1, and HLA-DR and T-lymphocyte subgroups and evaluated with flow cytometry. The obtained data were compared statistically. Results: When compared to the control tissue samples, higher rates of ICAM-1-positive cells, VCAM-1-positive cells and HLA-DR-positive cells were recorded in pterygium tissue samples. CD4 and CD8 lymphocytes were also found to be at higher levels when compared to the control group. There was a statistically significant difference between the two groups. Conclusion: When compared with normal conjunctival tissue, pterygium tissue had increased levels of T-lymphocyte infiltration and inflammatory markers demonstrating the possible contribution of cellular immunity to the pathogenesis.


Liver International | 2007

The effects of pentoxifylline on liver regeneration after portal vein ligation in rats

Uzer Kucuktulu; Etem Alhan; Yavuz Tekelioglu; Aysel Ozekin

Aim: To determine the effects of pentoxifylline, a methyl xanthine derivative on hepatic cell production of uninterferred lobe after portal vein branch ligation.


Acta Obstetricia et Gynecologica Scandinavica | 2006

Apoptotic and morphological features of the umbilical artery endothelium in mild and severe pre-eclampsia

Esin Yulug; Engin Yenilmez; Mesut A. Unsal; Sevim Aydin; Yavuz Tekelioglu; Haluk Arvas

Background. The pathology of the umbilical arterial endothelium in normal pregnancy and in pregnancy complicated with pre‐eclampsia remains unclear. In this study the changes that occur in the umbilical artery endothelial cells were examined and endothelial cell morphology and apoptosis were compared among control, mild, and severe pre‐eclamptic subjects. Methods. Umbilical cords with a gestational age of between 35 and 40 weeks were collected from women with normal pregnancies (n=17), mild pre‐eclampsia (n=10), and severe pre‐eclampsia (n=12). We studied the umbilical artery endothelial cells using flow cytometry, and light and electron microscopy. Apoptosis was measured using flow cytometry and the terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick end labeling technique. The Kruskall–Wallis variance analysis and Mann–Whitney U‐tests as post hoc were applied. Results. In mild pre‐eclamptics, the endothelial cells appeared ultrastructurally separated. A dilated endoplasmic reticulum, swollen mitochondria, and vanished mitochondrial cristae were observed. In severe pre‐eclamptics, the cells were disorganized, highly contracted and vacuolated, separated from each other, and protruding prominently into the lumen. The percentages of endothelial cells that underwent apoptosis in mild (p<0.017) and severe pre‐eclamptics (p<0.017) were higher than those in the controls. These apoptosis values were highest in severe pre‐eclamptics (p<0.0001). Conclusion. Apoptosis and structural disruptions in the arterial endothelium of severe pre‐eclamptics were prominent in all subjects. Increased endothelial apoptosis and structural disruptions are clinically related to intensity of pre‐eclampsia, and may be associated with adaptation of the endothelial cells to pre‐eclampsia.


Pediatric Hematology and Oncology | 2004

IN VITRO DETERMINATION OF THE APOPTOTIC EFFECT OF HEPARIN ON LYMPHOBLASTS USING DNA ANALYSIS AND MEASUREMENTS OF Fas AND Bcl-2 PROTEINS BY FLOW CYTOMETRY

Erol Erduran; Yavuz Tekelioglu; Yusuf Gedik; İsmail Bektaş; Sadan Hacisalihoglu

Heparin has an apoptotic effect beside its anticoagulant, anti-inflammatory, antihypertensive, and antiproliferative effects. In this study, the authors detected the percentages of apoptotic lymphoblasts and the expressions of apoptotic Fas protein and antiapoptotic Bcl-2 protein with flow cytometry in vitro after the incubation of lymphoblasts with heparin. Eleven newly diagnosed acute lymphoblastic leukemia (ALL) children were included in the study. Lymphoblasts were incubated in all different levels of heparin concentrations (0, 10, and 20 U/mL) and the percentages of apoptotic lymphoblasts and the percentages of Fas protein and Bcl-2 proteins were simultaneously measured by flow cytometry at 0, 1, and 2 h. At 0, 1, and 2 h, apoptosis was determined when heparin was added in 10- and 20-U/mL concentrations (p <. 05). The apoptotic effect of heparin on lymphoblasts was higher at the first hour than at 0 and 2 h in 10- and 20-U/mL heparin concentrations (p <. 01). The highest apoptosis was detected in the 20-U/mL heparin concentration at the first hour. The expression levels of Fas protein on lymphoblasts were higher at the first hour than at 0 and 2 h in 10- and 20-U/mL heparin concentrations (p <. 001). The highest expression of Fas protein was observed in the 20-U/mL heparin concentration at the first hour. The expression levels of Bcl-2 protein on lymphoblasts were lower at the first hour than at 0 and 2 h in 10- and 20-U/mL heparin concentrations (p <. 001). The lowest expression of Bcl-2 protein was detected in the 20-U/mL heparin concentration at the first hour. Increased concentrations of heparin had an increasing effect on the percentages of apoptotic lymphoblasts. The expression percentages of Fas protein on lymphoblasts also increased, whereas the expression percentages of Bcl-2 protein on lymphoblasts decreased (p <. 05). These results suggest that low-dose heparin may cause significant apoptosis of lymphoblasts in newly diagnosed ALL patients.


Current Stem Cell Research & Therapy | 2006

Therapeutic Use of Limbal Stem Cells

Avni Murat Avunduk; Yavuz Tekelioglu

Stem cells are defined as relatively undifferentiated cells that have the capacity to generate more differentiated daughter cells. Limbal stem cells are responsible for epithelial tissue repair and regeneration throughout the life. Limbal stem cells have been localized to the Palisades of Vogt in the limbal region. Limbal stem cells have a higher proliferative potential compared to the cells of peripheral and central cornea. Limbal stem cells have the capacity to maintain normal corneal homeostasis. However, in some pathological states, such as chemical and thermal burns, Stevens-Johnson syndrome, and ocular pemphigoid limbal stem cells fail to maintain the corneal epithelial integrity. In such situations, limbal stem cell transplantation has been required as a therapeutic option. In unilateral disorders, the usual source of stem cells is the contralateral eyes, but if the disease is bilateral stem cell allografts have to be dissected from family members or cadaver eyes. The advent of ex vivo expansion of limbal stem cells from a small biopsy specimen has reduced the risk of limbal deficiency in the donor eye. Concomitant immunosuppressive therapy promotes donor-derived epithelial cell viability, but some evidences suggest that donor-derived epithelial stem cell viability is not sustained indefinitely. Thus, long-term follow-up studies are required to ascertain whether donor limbal stem cell survival or promotion of recolonization by resident recipient stem cells occurs in restored recipient epithelium. However, this is not an easy task since a definitive limbal stem cell marker has not been identified yet. This review will discuss the therapeutic usage of limbal stem cells in the corneal epithelial disorders.


Chemotherapy | 2004

Effects of Dexamethasone, All-Trans Retinoic Acid, Vitamin D3 and Interferon-α on FO Myeloma Cells

Feyyaz Ozdemir; Nilgun Esen; Ercument Ovali; Yavuz Tekelioglu; Mustafa Yilmaz; Fazil Aydin; Halil Kavgaci; Cem Boruban

Background: Since multiple myeloma responds poorly to conventional chemotherapy or radiotherapy, new therapeutic approaches are needed. This study investigated the effects of dexamethasone, all-trans retinoic acid (ATRA), the active metabolite of vitamin D3 [1,25(OH)2D3] and interferon-α on FO mouse myeloma cells (non-immunoglobulin-secreting myeloma cell line) in single drug or drug combination groups in vitro. Methods: Apoptosis ratio and change in cell counts in 4 single drug groups (dexamethasone, ATRA, vitamin D3 and interferon-α) and 6 combination drug groups (dexamethasone + vitamin D3, dexamethasone + ATRA, dexamethasone + interferon-α, vitamin D3 + ATRA, vitamin D3 + interferon-α, interferon-α + ATRA) were compared with the control group. Results: When treatment groups were compared with the control group, there was a significant increase in apoptosis in all, but this was most prominent in the group treated with dexamethasone alone. The apoptosis ratios were 0.10 and 6.82% in the control and dexamethasone-only groups, respectively. We also found that there was a significant decrease in cell count, particularly in the dexamethasone-only, ATRA-only, and ATRA-vitamin D3 combination groups. Conclusion: ATRA, interferon-α, vitaminD3 and particularly dexamethasone have significant effects on FO mouse myeloma cells resulting in a decreased cell count and an increased apoptosis ratio. This study should be repeated with human myeloma cell lines for further information.


Gynecologic and Obstetric Investigation | 1999

FIGO Committee for the Ethical Aspects of Human Reproduction and Women’s Health

Petra L.M. Zusterzeel; Maarten F. C. M. Knapen; Eva Maria Roes; Régine P.M. Steegers-Theunissen; Wilbert H.M. Peters; Hans M.W.M. Merkus; A. Abate; A. Brigandi; F.G. Abate; F. Manti; V. Unfer; M. Perino; Eric A.P. Steegers; Tanya K. Sorensen; M. Rene Malinow; Michelle A. Williams; Irena B. King; David A. Luthy; Mehmet Özeren; Vedat Aydemir; Yavuz Tekelioglu; Kenan Topcuoglu; Hasan Bozkaya; Hulusi Gürel; Sebahat Atar Gürel; Hakan Kaya; Baha Oral; Keiichi Fujiwara; Takako Shirotani; Ichiro Kohno

The FIGO Committee for the Ethical Aspects of Human Reproduction and Women’s Health considers the ethical aspects of issues that impact the discipline of Obstetrics, Gynecology and Women’s Health. The following documents represent the result of that carefully researched and considered discussion. This material is not intended to reflect an official position of FIGO, but to provide material for consideration and debate about these ethical aspects of our discipline for member organizations and their constituent membership. Definition of Pregnancy

Collaboration


Dive into the Yavuz Tekelioglu's collaboration.

Top Co-Authors

Avatar

Avni Murat Avunduk

Karadeniz Technical University

View shared research outputs
Top Co-Authors

Avatar

Erol Erduran

Karadeniz Technical University

View shared research outputs
Top Co-Authors

Avatar
Top Co-Authors

Avatar

Yusuf Gedik

Karadeniz Technical University

View shared research outputs
Top Co-Authors

Avatar

Ercument Ovali

Karadeniz Technical University

View shared research outputs
Top Co-Authors

Avatar

Orhan Deger

Karadeniz Technical University

View shared research outputs
Top Co-Authors

Avatar

Esin Yulug

Karadeniz Technical University

View shared research outputs
Top Co-Authors

Avatar

Adem Türk

Karadeniz Technical University

View shared research outputs
Top Co-Authors

Avatar

Engin Yenilmez

Karadeniz Technical University

View shared research outputs
Top Co-Authors

Avatar

Haluk Arvas

Karadeniz Technical University

View shared research outputs
Researchain Logo
Decentralizing Knowledge