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N Tatsumi

Publications and source records attributed to N Tatsumi.

At least 19 recordsLinked to original sources
PubMed1995

Constitutive expression of the thrombopoietin gene in a human hepatoma cell line.

The gene of thrombopoietin (TPO) has been cloned and identified to be identical to gene of the c-mpl ligand. It is known that the mRNA of TPO is expressed in liver and kidney. However, it is not clarified which cells in the liver produce TPO. Using a human hepatoma cell line, HepG2, we demonstrated that the TPO mRNA was expressed by liver parenchymal cells without any stimulation. To clarify the regulation of the expression of the TPO mRNA in HepG2 cells by cytokines, we assessed the effects of 5 cytokines, transforming growth factor-beta 1, activin A, platelet-derived growth factor, hepatocyte growth factor, and interleukin-6. These cytokines have no significant regulative effect on the expression of the TPO mRNA in HepG2 cells. Our results suggest that liver parenchymal cells may be the TPO producing cells and also suggest that some hepatoma cells may produce TPO constitutively.

Base Sequence↗
PubMed1995

Down-modulation of c-kit mRNA and protein expression by erythroid differentiation factor/activin A.

We examined the effects of erythroid differentiation factor (EDF)/activin A on the expression of c-kit mRNA and protein in murine erythroleukemia (MEL) cells. EDF/activin A induced MEL cells to benzidine positive cells. Northern blot analysis showed that the c-kit mRNA expression was reduced synchronously with increase of beta-globin and uroporphyrinogen decarboxylase gene expression during EDF/activin A induced erythroid differentiation. Scatchard analysis indicated that the cell surface receptor number was reduced without change of affinity during differentiation. Our results suggest that EDF/activin A may act as a natural regulator of erythropoiesis with modulation of c-kit gene expression.

Activins↗
PubMed1995

Urinary sediment analyzed by flow cytometry.

A flow cytometer for the automated analysis of urinary sediment was designed, and its performance was examined by the evaluation of 821 specimens. Auramine O, a dye for DNA and RNA, was used for the staining of the sediment. Urine (5 ml or more) was processed by the instrument for sediment analysis. Conventional microscopic analysis was done for comparison. The RBC count, the WBC count, and the number of bacterial cells, epithelial cells, and casts found by the flow cytometer and by microscopy were compared. Correlation was high for all these results. The overall sensitivity, specificity, and efficiency (accuracy) in the items analyzed were 84.7%, 57.8%, and 67.2%, respectively. One hundred specimens could be analyzed by the instrument per hour. The instrument seemed useful for screening for urinary tract disorders to identify specimens that should be analyzed microscopically in routine laboratories.

Adolescent↗
PubMed1995

[Present and future of classification for white cells and leukemic cells in the routine clinical laboratory].

Renovation of laboratory medicine has been greatly advanced in the past decade. White cell differentiation has been done with the automated blood cell counter with high reliability with the combination of flow cytometry. Specific monoclonal antibodies have made FAB classification more precise, while the traditional cell classification still gives some extent of uncertainty for the decision of cell typing. High resolution chromosome analysis and DNA analysis enable one to define genetical leukemia types and patients' prognosis. Clinically the hematological data reported from the routine laboratory are regarded as very reliable, but an interpretation should be made carefully to select the patient treatment and prediction of prognosis. Here, four speakers were selected to show the present problems and some resolution for identification of white cells and leukemia cells. The importance of standardization work was also discussed for identification of white cells and leukemia cells examined by the traditional Romanovsky stain, automated blood cell counter, flow cytometric method, and chromosomal and DNA analytic methods. We concluded that all those methods should be standardized and interpretation would be harmonized to give common answers for clinical decisions.

Chromosome Mapping↗
PubMed1995

[Further evolution and leukocyte differential using an automated blood cell counter].

In the leukocyte differential, morphological differential has been usually performed with chromatoaffinity of blood cells, but physical differential is recently performed with biophysicochemical characteristics of blood cells using an automated blood cell counter. The trend of the leukocyte differential has changed to physical differential (automated count method) from morphological differential (eye count method). In the automated count method, leukocytes are differentiated into neutrophils, lymphocytes, monocytes, eosinophils and basophils according to the predetermined region of each leukocyte population on the cytogram using an automated blood cell counter. An automated count method is very useful for the screening test in the laboratory because of its high precision and accuracy for the normal samples. However, it is not easy to identify abnormal cells such as leukemia cells by an automated count method. Therefore, an automated count method dealing with various suspect flags generated using an automated blood cell counter must be used for such abnormal samples. In case of absolutely few leukemia cells in the peripheral blood during complete remission, the automated count method can not detect a leukemia cell and no suspect WBC flags are recognized by the automated blood cell counter. Development of an automated blood cell counter with a higher efficiency than now and a standard automated count method is awaited in the clinical laboratory.

Automation↗
PubMed1994

Transplantation of allogeneic peripheral blood stem cells after myeloablative treatment of a patient in blastic crisis of chronic myelocytic leukemia.

A 48-year-old man in blastic crisis of chronic myelocytic leukemia received a transplant of allogeneic peripheral blood stem cells. The donor was his HLA-identical sister, who refused to donate bone marrow cells, but agreed to donate peripheral blood stem cells. The patient received standard transplant conditioning with cyclophosphamide (120 mg/kg) and busulfan (16 mg/kg). Peripheral blood stem cells were mobilized with granulocyte colony stimulating factor and collected by apheresis. After transplantation, the white blood cell count and the result of microscopic analysis of the bone marrow became normal, and the leukocyte karyotype became 46XX. DNA fingerprinting showed complete chimerism. Graft-versus-host disease was suppressed with cyclosporine and methyl-prednisolone. The patient died of recurrence of leukemia on day 102+.

Blast Crisis↗
PubMed1994

Treatment with cytosine arabinoside and granulocyte colony-stimulating factor in patients with myelodysplastic syndrome and its leukemic phase.

Twenty-one patients with myelodysplastic syndrome (MDS) or overt leukemia resulting from MDS were treated with recombinant human granulocyte colony-stimulating factor (rhG-CSF) and cytosine arabinoside (Ara-C). Ara-C was administered in a dose of 20 mg/m2 every 12 h for 5 days and after 2 days 125 micrograms of rhG-CSF was administered for 10 days. After recovery of the leukocyte count the therapy was repeated, doubling the dose of Ara-C serially when possible. Of 13 patients with MDS, four achieved complete remission (CR), two good response (GR), two minor response (MR), and five no response (NR). Of eight patients with overt leukemia from MDS, only one with hyperplastic bone marrow achieved a partial response (PR) and the remaining seven achieved NR. The efficacy of the combination of rhG-CSF and Ara-C in the treatment of MDS and its leukemic phase is discussed, including at which time rhG-CSF should be administered: before, after or concomitantly with Ara-C. Multicenter randomized studies are needed in the evaluation of this combination therapy.

Adult↗
PubMed1993

Cell kinetic effects of granulocyte colony-stimulating factor on the sensitivity of nonlymphocytic leukemia cells to cytosine arabinoside.

We measured the percentage of proliferating cells in peripheral blood and bone marrow of patients with nonlymphocytic leukemia by flow cytometry and immunostaining with antibodies to proliferating cell nuclear antigen (PCNA) and Ki-67. We evaluated the effects of granulocyte colony-stimulating factor (G-CSF) on nonlymphocytic leukemia cells. The S phase cell ratio, PCNA positive cell ratio, and Ki-67 positive cell ratio were higher after culture with G-CSF than culture without G-CSF. The ratio of viable cells was lower after culture with G-CSF followed by cytosine arabinoside (Ara-C) than culture with Ara-C alone. The number of clonogenic leukemic cells in methylcellulose was also smaller after culture with G-CSF followed by Ara-C than Ara-C alone. Our results suggest that the administration of G-CSF before induction chemotherapy enhances the sensitivity of antitumor agents against leukemic cells.

Adolescent↗
PubMed1992

Measurement of the zeta potential of human platelets by the use of laser-light scattering.

An instrument was developed to detect the shift in scattering of laser light that occurs when particles in suspension move in a chamber with an electrical load. The instrument measures the zeta potential of particles. We applied the instrument to study human blood cells. Platelet-rich plasma was used because of the stability of the suspension, without the sedimentation or autoaggregation that is often seen with red or white blood cells. The reproducibility of the measurements was satisfactory when there were enough platelets in the suspension. Platelets from healthy controls (n = 136) had a potential of -14.20 +/- 1.64 mV at the detection angle of 17.1 degrees. Platelets from patients with essential thrombocytosis (n = 16) or polycythemia vera (n = 8) had higher potentials than the healthy controls.

Blood Platelets↗
PubMed1992

Monoclonal antibody to human plasma gelsolin.

Human plasma gelsolin was purified by column chromatography. The method yielded a protein of high purity and activity. Using this protein, we produced monoclonal antibody (Mab H6B11) against human plasma gelsolin by somatic cell fusion. This monoclonal antibody reacted in a dose-dependent manner with gelsolin derived from human plasma and platelets and neutralized depolymerizing activity to F-actin. It differed from the commercially available substance (Mab G4896; Sigma) in that the time required for the reaction between the antigen and antibody in the enzyme-linked immunosorbent assay could be shortened by one-third. The antibody was judged to be useful in assays for elucidating the physiological role of plasma gelsolin.

Animals↗
PubMed1992

Automatic measurement of hemoglobin F in blood obtained from patients with hemoglobin E/E and beta-thalassemia/hemoglobin/E.

This paper presents an automated determination of hemoglobin (Hb) F in Hb E/E disease using Hi-Auto A1c. Blood specimens collected in Bangkok were frozen, and sent to Japan by air mail for the determination. The automatically determined values showed a high correlation with the values obtained by the classical alkali denaturation method. Hb E/E cases showed 4.24 +/- 1.75% of Hb F. On the other hand, Hb, Hct, MCV and MCH in the disease samples were lower than in the controls, but higher than those of beta-thalassemia/HbE disease. From the results it was concluded that Hb E/E could be differentiated from beta-thalassemia/HbE by combination of Hb F value and MCH or Hb in CBC.

Adult↗
PubMed1992

[Recent trend in G-CSF therapy and clinical laboratory tests].

Granulocyte colony-stimulating factor (G-CSF) has strong leukopoietic activity and it is used for patients with leukopenia during leukemia chemotherapy. However, some leukemia cells show a high affinity to G-CSF and are driven to proliferative phase. In our laboratory, we developed two testing methods. 1) Flow cytometric method on G-CSF susceptibility of leukemia cells using FITC-labeled G-CSF, and 2) Immunohistochemical method for detecting the ratio of cells driven from dormant phase to proliferative phase by G-CSF with anti-PCNA antibody and Ki-67 antibody. In MDS patients G-CSF administration induced an increase of cells in proliferative phase. The patients treated with cytosine arabinoside following G-CSF showed hematologically good improvement. A new mode of therapy using G-CSF in combination with other cytokines or antileukemic agents will be developed in the near future for treatment of leukemia patients.

Combined Modality Therapy↗
PubMed1992

Size distribution curves of blood cells in thalassemias and hemoglobin H diseases.

Thalassemias and hemoglobinopathies in Thailand have been examined with a blood cell counter based on electroimpedance principle and obtained size distribution curves of red cells and platelets. Among various disorders, beta-thalassemia/hemoglobin E and homozygous hemoglobin Constant Spring showed severe anemia. Their red cell size distribution curve shifted to the left and overlapped with the platelet size distribution curve. Red cell distribution width expressed by coefficient of variation and the degree of the overlapping were stronger in beta-thalassemia/HbE than HbH. Heterozygous beta-thalassemia showed a narrow red cell distribution curve width with small standard deviation and low England's value. Although the overlapping of size distribution curves cause inaccurate red cell count and platelet count, careful observation of the size distribution curves was proved to have high diagnostic value.

Blood Platelets↗