Yazar "Özgen Ü." seçeneğine göre listele
Listeleniyor 1 - 5 / 5
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe Further elucidation of mechanism of resistance to vincristine in myeloid cells: role of hypochlorous acid in degradation of vincristine by myeloperoxidase(Nature Publishing Group, 2000) Özgen Ü.; Savaşan S.; Stout M.; Buck S.; Ravindranath Y.Inherent resistance of myeloblasts to vincristine (VCR) has been related to the activity of myeloperoxidase (MPO) which can degrade VCR in the presence of hydrogen peroxide (H2O2). We investigated the relationship between VCR degradation and hypochlorous acid (HOCl) generation from the reaction of H2O2 with chlorine (Cl) as catalyzed by MPO. A cell-free system, three human leukemia cell lines (CEM/CCRF, HL-60, U937) and 15 bone marrow samples from children with acute myeloid leukemia (AML) were studied. VCR cytotoxicity was evaluated by MTT assay and by quantitative measurement of apoptosis. In vitro levels of VCR in cell-free systems were measured by high performance liquid chromatography (HPLC), and intracellular HOCl levels by oxidation of 5-thio-2-nitrobenzoic acid with the accompanying decrease in the absorbency at 412 nm. VCR was degraded by increasing concentrations of HOCl in cell-free systems and this activity was inhibited by taurine, which is known to block HOCl activity. This finding was confirmed by the VCR cytotoxicity studies on cell lines. The HOCl-producing myeloblasts from patients were resistant to VCR. In five samples out of eight HOCl was also detected extracellularly. These results suggest that oxidation by HOCl may be the final step in VCR degradation catalyzed by MPO through its action on intracellular H2O2 and Cl.Öğe Injuries of large vessels in high stage neuroblastoma surgery. A case report(1999) Koltuksuz U.; Gürsoy M.H.; Aydinç M.; Özgen Ü.; Ege E.; Mutus M.Complete resection of the primary lesion in stage III neuroblastoma improves survival. Neuroblastoma has a tendency towards surrounding and infiltrating the large vessels, leading to injuries during tumor resection. We operated on a stage Ill neuroblastoma, which resulted in the right and left common iliac artery and vein damage. The right common iliac artery and, veins were repaired by end to end anastomosis. There was a long gap between the two ends of the left common iliac artery and it was repaired using a mesenteric vein (marginal vein of the colon) graft. Digital subtraction angiography performed 6 months after the operation did not reveal any stenosis or aneurysmatic changes in the anastomoses. We conclude that short segments of large vessels may be sacrificed during the resection of neuroblastomas invading the vessel wall, and the resulting defects may be repaired by end to end anastomosis, or even by substituting mesenteric vein grafts, for the purpose of total or near total removal.Öğe Iron deficiency and iron deficiency anemia in infants and young children at different socioeconomic groups in Istanbul(2001) Soylu H.; Özgen Ü.; Babalio?lu M.; Aras Ş.; Sazak S.Iron deficiency anemia (IDA) is a common health problem mainly in developing countries. It is preceded by iron deficiency (ID), and recent studies showed that both situations may cause permanent neurological problems though they were treated. In this study, we investigated the frequency of ID and IDA among different socioeconomic groups in Istanbul. Effects of gender, nutritional practices, and adequate breast-feeding duration (? 6 months) on development of ID and IDA were also evaluated. The study consisted of 166 children aged 5 to 36 months of life. The children were evaluated within four socioeconomic levels. The children were found as iron deficient in 24.7%, anemic with iron deficiency in 47.6%, and normal in 27.7%. Thus, 72.3% of the children were affected from ID. The frequencies of ID and IDA were not different between the socioeconomic groups (p> 0.05). Furthermore, they were also not affected by gender and nutritional practices (p> 0.05), except adequate breast-feeding duration that was significantly found as protective (p< 0.05). Our results have indicated that ID and IDA remain important and unresolved health issues in our population. Permanent neurological/mental damages should be considered and public health policies must be developed urgently to protect our younger population, by means of our future.Öğe Relationship between activation and apoptosis in platelets(2007) Özgen Ü.; Özerol E.; Aminci M.Phosphatidylserine (PS) externalization is a marker for the nucleated cell apoptosis, and refers cellular activation rather than apoptosis in platelets. On the other hand, several similarities exist between platelet activation and apoptosis in nucleated cells. Herewith we investigated the relationship between platelet activation and platelet apoptosis. Platelets isolated from fresh blood of 22 healthy volunteers were incubated with and without calcium ionophore A23187. Platelet activation was evaluated with CD62P and CD63 antibodies, whereas apoptosis with intracellular anti caspase 3-antibody and JC-1 cationic dye. In order to detect PS externalization we used Annexin V by flow cytometry at the beginning, 20th minute and 5th hours of the incubation, respectively. There were positive correlations between caspase-3 activation and PS externaization, ??m depolarization, CD63, and also between PS externaization and CD62P in incubations with A23187 at 5th hours of incubations. These results suggest that there is a relationship between activation and apoptosis in platelets, and platelet activation may progress to platelet apoptosis. © Turkish Society of Hematology.Öğe Reversible posterior leucoencephalopathy in an 11 year-old male child with lupus nephritis(2010) Tabel Y.; Akin I.M.; Güngör S.; Karakurt C.; Özgen Ü.Systemic lupus erythematosus is a chronic inflammatory disease characterized by highly diverse clinical manifestations. The major organ system involvements in childhood systemic lupus erythematosus are similar to those found in adults. Recognizing and reversing secondary causes of central nervous system abnormalities in patients with systemic lupus erythematosus are essential for preventing long-term neurologic disability or death. In this manuscript, we present an 11 year-old male followed up in our clinic, who had the very rare involvement and complications of systemic lupus erythematosus in childhood. He developed a reversible posterior leucoencephalopathy after the first dose of cyclophosphamide, but cyclophosphamide therapy was not stopped as there was no clear evidence in the literature related to the role of this drug in reversible posterior leucoencephalopathy. The patient has now recovered.
