Yahya Büyükaşik

Publications (8)16.25 Total impact

• Article: Congenital dysgranulopoietic neutropenia.

  Lale Olcay, Sevgi Yetgin, Esra Erdemli, Manuela Germeshausen, Dilek Aktaş, Yahya Büyükaşik, Hamza Okur
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  ABSTRACT: We investigated a 15-year-old female with congenital dysgranulopoietic neutropenia (CDN) and her non-neutropenic mother who had recurrent stomatitis. In both patients, cells of the neutrophilic, eosinophilic, monocytic, megakaryocytic, and basophilic series were dysmorphic. Plasmacytoid lymphocytes and mild megaloblastic erythroid precursors were present. Bleeding times of both patients were prolonged. The mother had a secondary aggregation defect; the number of the plasmacytoid lymphocytes, dense granules of platelets, and dysmorphic neutrophils, neutrophil chemotaxis, and myeloperoxidase content fluctuated according to the presence or not of aphthae. The daughter's karyotype revealed 46,XX/46,XX, t(1;8). No ELA2 or G-CSFR mutation was detected. These findings support stem cell involvement in CDN.
  Pediatric Blood & Cancer 02/2008; 50(1):115-9. · 1.89 Impact Factor
• Article: Over-expression of angiotensin-converting enzyme (CD 143) on leukemic blasts as a clue for the activated local bone marrow RAS in AML.

  Salih Aksu, Yavuz Beyazit, Ibrahim C Haznedaroglu, Hande Canpinar, Murat Kekilli, Aysegul Uner, Nilgün Sayinalp, Yahya Büyükaşik, Hakan Goker, Osman I Ozcebe
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  ABSTRACT: Local bone marrow renin-angiotensin system (RAS) is an autocrine-paracrine system affecting hematopoiesis. Angiotensin II type 1a (AT1a) receptors are present on the CD34+ hematopoietic stem cells. Angiotensin II stimulates the proliferation of bone marrow and umbilical cord blood hematopoietic progenitors. There are preliminary data that local RAS might also be involved in leukemogenesis. ACE hyper-function may lead to the acceleration of negative hematopoietic regulator peptide, AcSDKP, metabolism, which in turn lowers its level in the bone marrow micro-environment, finally removing the anti-proliferative effect of AcSDKP on the hematopoietic cells and blasts. Renin expression could have a role on the leukemia development and angiotensin may act as an autocrine growth factor for acute myeloid leukemia (AML) cells. The aim of this study is to search ACE (CD 143) surface antigen by flow-cytometric analyses on the leukemic blast cells taken from the bone marrow of the patients with AML. Bone marrow aspiration materials and peripheral blood samples were obtained from 11 patients with AML (eight males, three females; aged 46 (range 26-67) years) and six patients with non-malignant hematological disorders (four males, two females; aged 56 (range 22-71) years). ACE (CD 143) surface antigen was shown to be over-expressed in leukemic myeloid blast cells. ACE is positively correlated with bone marrow blast count. Elucidation of the pathological activity of the local RAS-mediated regulation of the leukemogenesis is both pathobiologically and clinically important, since the angiotensin peptides represent a molecular target in the disease management.
  Leukemia and Lymphoma 06/2006; 47(5):891-6. · 2.58 Impact Factor
• Article: Seropositive arthritis in chronic lymphocytic leukemia: a remark on B cell-mediated autoimmunity.

  Ibrahim Koral Onal, Levent Ozçakar, Omer Dizdar, Yahya Büyükaşik, Semra Dündar
  Rheumatology International 10/2005; 25(7):569-70. · 1.88 Impact Factor
• Article: Endogenous thrombopoietin levels during the clinical management of acute myeloid leukaemia.

  Can Gonen, Ibrahim C Haznedaroglu, Salih Aksu, Ebru Koca, Hakan Göker, Yahya Büyükaşik, Nilgün Sayinalp, Osman Ozcebe, Semra Dündar
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  ABSTRACT: Thrombocytopenia represents a major problem in the management of acute myeloid leukaemia (AML). The data regarding the alterations of endogenous thrombopoietin (TPO) regulation during the clinical course of AML are limited. The aim of this study was to investigate endogenous TPO dynamics in association with platelets during the clinical course of AML. We serially measured both TPO and platelets concurrently over the entire treatment period of newly diagnosed patients receiving both remission induction and consolidation chemotherapies. The median concentration of TPO in AML patients at the initial diagnosis was 469.71 pg/ml and increased significantly during the aplastic period due to remission induction chemotherapy (median: 1085.33 pg/ml) but then decreased to a level (median: 45.26 pg/ml) encountered in the healthy control subjects (median: 56.90 pg/ml). In the cytopenic period due to consolidation treatment, TPO level again increased significantly to a high level (median: 891.38 pg/ml) during the platelet nadir, but decreased toward normal (median: 100.75 pg/ml) after the thrombocytopenic period had elapsed. In conclusion, endogenous TPO levels exhibit an inverse fluctuation in relation to platelet counts during the clinical course of AML. Pharmacological stimulation of thrombopoiesis in AML with novel molecules, including the recombinant thrombopoietins and the small peptide agonists, should be based on a critical administration strategy that must consider the endogenous levels of TPO. TPO levels in distinct AML disease states may explain the unsuccessful recombinant TPO trials and could help to design better strategies for 'pharmacological stimulation of thrombopoiesis' in AML.
  Platelets 03/2005; 16(1):31-7. · 1.85 Impact Factor
• Article: Piebaldism associated with congenital dyserythropoietic anemia type II (HEMPAS).

  Seyfettin Köklü, Derun Ertuğrul, Ahmet Mesut Onat, Sema Karakuş, Ibrahim C Haznedaroğlu, Yahya Büyükaşik, Nilgün Sayinalp, Osman Ozcebe, Semra V Dündar
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  ABSTRACT: Congenital dyserythropoietic anemias (CDAs) are a group of relatively rare inherited anemias. They are characterized by ineffective erythropoiesis and classified as three major groups and a number of variants. CDA type II, also known as hereditary erythroblastic multinuclearity with a positive acidified serum test (HEMPAS), is the most frequent one. A number of associations with CDA II have been reported, although each described only one or a few patients. Here we presented a piebald woman with vaginal atresia who was tested for anemia and diagnosed as CDA type II. Piebaldism and anemia association were previously described in the mouse. Our case was the first that shows the features of both piebaldism and CDA in the same patient. This association may suggest a stem cell defect to cause both hematopoietic and cutaneous manifestations.
  American Journal of Hematology 04/2002; 69(3):210-3. · 4.67 Impact Factor
• Article: Circulating thrombopoietin in clonal versus reactive thrombocytosis.

  Sema Karakuş, Osman I Ozcebe, Ibrahim C Haznedaroğlu, Hakan Göker, Düzgün Ozatli, Ali Koşar, Yahya BüyükaşIk, Derun Ertuğrul, Nilgün SayInalp, Serafettin KirazlI, Semra V Dündar
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  ABSTRACT: The aim of this study is to assess circulating thrombopoietin concentrations in patients with both clonal and reactive thrombocytosis (RT), which are two distinct categories of extreme platelet production circumstances. Investigation of the thrombopoietin levels in clonal versus reactive thrombocytosis may help us to understand the interactions of this key regulatory cytokine and the conditions in which abnormally increased platelet formation exist. Thrombopoietin levels were measured in patients with platelet counts greater than 500 x1 0(3) microl(-1). The study population consisted of 21 patients with RT (13 with iron deficiency anemia, and 8 with rheumatoid arthritis), 24 patients with clonal thrombocytosis (six with essential thrombocytosis, three with myelofibrosis, eight with chronic myelogenous leukemia, and seven with polycythemia vera (PV)) and 16 healthy subjects were used as controls. The median plasma thrombopoietin concentration was 100.5 pg ml(-1) in patients with RT, 467 pg ml(-1) in patients with clonal thrombocytosis and 62.65 pg ml(-1) in the control group. The thrombopoietin concentration was found to be higher in the patients with primary thrombocytosis when compared to the control group (p=0.001), as well as in patients with RT (p=0.002). However, there was no statistically significant difference between the patients with RT and the control group (p=0.14). There was no correlation between thrombopoietin levels and the platelet counts in patients with clonal thrombocytosis, including essential thrombocythemia (ET). CONCLUSIION: Increased levels of thrombopoietin were found in patients with clonal thrombocytosis versus patients with RT and control subjects as well. Defective clearance of thrombopoietin by megakaryocytes and platelets due to a reduced number of thrombopoietin receptors may be the causative mechanism behind this. These results indicate that plasma thrombopoietin levels may be helpful in distinguishing between clonal and reactive thrombocytosis.
  Hematology 03/2002; 7(1):9-12. · 1.49 Impact Factor
• Article: Unchanged global fibrinolytic capacity despite increased factor VIIa activity in Behçet's disease: evidence of a prethrombotic state.

  Düzgün Ozatli, Nilgün Sayinalp, Yahya Büyükaşik, Sema Karakuş, Ibrahim Celalettin Haznedaroglu, Serafettin Kirazli, Osman Ozcebe, Semra V Dündar
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  ABSTRACT: The aim of this study was to evaluate coagulation and fibrinolytic systems in Behçet's disease (BD). Accordingly, various parameters of the coagulation and fibrinolytic systems were investigated in 39 patients with BD and 31 age- and sex-matched healthy volunteers as the control group. Seven of these patients with BD had histories of thrombotic complication. Three were found to have decreased protein S activity, and one patient had diminished protein C activity. Each of those patients had experienced a thromboembolic event. Activated protein C resistance was present in two patients, one of whom had had a thromboembolic episode. Activated FVII (FVIIa), fibrinogen, and cholesterol levels were significantly higher in patients with BD than in the control group. In the patient group, plasma FVIIa level was inversely correlated with age. Plasma global fibrinolytic capacity (GFC) did not differ between the patients and control group. No statistically significant difference was found in the GFC and FVIIa levels between patients with and without histories of thrombosis. Although the coagulation system was activated in vivo in patients with BD, there was no reactive activation in the fibrinolytic system to counteract the activated coagulation system. These findings suggest a relative hypofibrinolytic state in BD.
  Rheumatology International 02/2002; 21(4):137-40. · 1.88 Impact Factor
• Article: Autoimmune hemolytic anemia in Philadelphia positive chronic myeloid leukemia with t(7;14) anomaly after 5 years of interferon alpha treatment.

  Aydin Köksal, Düzgün Ozatli, Ibrahim C Haznedaroğlu, Asuman Sunguroğlu, Sema Karakuş, Yahya Büyükaşik
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  ABSTRACT: A 41-year-old woman, Philadelphia positive chronic myeloid leukemia patient, had progressive decline in hemoglobin levels. She had been receiving interferon alpha treatment for five years. Autoimmune hemolytic anemia was diagnosed. Subsequent bone marrow examination revealed translocation t(7;14). She was placed on prednisone treatment. The patient responded to prednisone as treatment for the hemolytic process. The result of a direct Coombs' test remained positive. The patient died shortly after the diagnosis of autoimmune hemolytic anemia. Autoimmune hemolytic anemia should be considered in the evaluation of chronic myeloid leukemia patients with a sudden decrease in hemoglobin levels.
  Haematologia 02/2002; 32(2):163-7.