K Arai

Hirosaki University, Khirosaki, Aomori Prefecture, Japan

Are you K Arai?

Claim your profile

Publications (12)34.03 Total impact

  • [show abstract] [hide abstract]
    ABSTRACT: Acute megakaryoblastic leukaemia (M7) and transient myeloproliferative disorder in Down's syndrome (TMD) are characterized by rapid growth of abnormal blast cells which express megakaryocytic markers. To clarify properties of the blast cells in M7 and TMD cases, we examined erythroid markers expression in blasts from six cases with M7 and seven cases with TMD in this study. Erythroid-specific mRNAs encoding 7-globin and erythroid 6-aminolevulinate synthase were found to be expressed in blasts from most of these cases, indicating that majorities of the blasts in M7 and TMD cases have erythroid and megakaryocytic phenotypes. We also found that mRNAs encoding GATA-1 and GATA-2 are expressed in all these cases. These results suggest that M7 blasts and TMD blasts correspond to the erythroid/megakaryocytic bipotential progenitor cells.
    British Journal of Haematology 03/2008; 90(3):607 - 614. · 4.94 Impact Factor
  • Medical and Pediatric Oncology 09/2001; 37(2):153-4.
  • [show abstract] [hide abstract]
    ABSTRACT: Significantly low serum lipid levels are occasionally seen at the time of diagnosis in children with aplastic anemia (AA). The aim of the present study was to clarify the pathologic and clinical significance of pretreatment serum lipid levels in AA. A questionnaire seeking precise data about AA in pediatric patients, including the initial laboratory data at the time of onset of AA and the clinical course of these patients, was sent to 18 institutes in Japan; 13 institutes responded to the questionnaire. In this retrospective study, data concerning hematologic examination and serum lipids were available for analysis in 127 children with AA. Serum lipoprotein patterns were analyzed using conventional agarose electrophoresis in eight patients. In order to elucidate the cause of hypolipidemia in AA, we assayed serum macrophage colony stimulating factor (M-CSF), which is well known to have apparent cholesterol-lowering activity, by using an enzyme-linked immunosorbent assay in seven patients with hypocholesterolemia and compared the results with those obtained in patients with iron-deficiency anemia (IDA). We found that pretreatment total cholesterol (TC) and triglyceride levels in the serum correlated well with counts of both nucleated cells and hemopoietic cells in the bone marrow (BM) and were inversely correlated with the lymphocyte ratio in both the BM and peripheral blood. Patients with serum TC lower than 150 mg/dL showed a poor response to any form of therapy except BM transplantation. There was no difference in the serum lipoprotein patterns between the controls and patients examined. The serum M-CSF level was significantly higher in patients with TC levels lower than 150 mg/dL compared with controls. These results indicate that the pretreatment serum lipid level may reflect hematopoietic activity within the BM and can help to predict the therapeutic response of each case of AA to treatment with immunosuppressive drugs, corticosteroids and anabolic steroids. These results also indicate that M-CSF may be one of the contributing causes of the hypocholesterolemia that occurs in both AA and IDA.
    Pediatrics International 01/2001; 42(6):613-9. · 0.88 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: The transcription factor NF-E2, a heterodimeric protein complex composed of p45 and small Maf family proteins, is considered crucial for the proper differentiation of erythrocytes and megakaryocytes in vivo. We report the results of studies aimed at understanding the regulatory mechanisms controlling p45 gene expression in erythroid cells. Human p45 mRNAs have two alternative isoforms, aNF-E2 and fNF-E2, and these isoforms are transcribed from the alternative promoters. We investigated lineage-specific expression of both isomers in human erythroid and megakaryocytic cells by reverse transcriptase polymerase chain reaction or Northern blot analysis. For functional characterization of both promoters, plasmids in which reporter genes were placed under the control of a series of truncated or mutated promoter fragments were transfected to human hematopoietic cell lines. When CD34(+) cells isolated from human cord blood were induced to unilineage erythroid or megakaryocytic differentiation in liquid suspension culture, both transcripts, although barely detected at day 0, were induced in both erythroid and megakaryocytic cultures. fNF-E2 mRNA was found to be more abundant in erythroid cells than megakaryocytic cells at day 7 of culture. Although both isomers were expressed in human erythroid-megakaryocytic cell lines, megakaryocytic maturation with loss of erythroid phenotype induced by phorbol 12-myristate 13-acetate (PMA) resulted in exclusive downregulation of fNF-E2, suggesting that fNF-E2 promoter is more erythroid specific. Functional analysis of fNF-E2 promoter showed that the promoter is active only in erythroid-megakaryocytic cells and that the double GATA site in the proximal region is necessary for its efficient activity. These results suggest that GATA proteins, which govern the differentiation of erythroid lineage cells, are required for full promoter activity of the p45 gene.
    Experimental Hematology 11/2000; 28(10):1113-9. · 2.91 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: We report a case of Epstein-Barr virus (EBV)-associated hemophagocytic lymphohistiocytosis (HLH) with clonal karyotype abnormality. A 5-year-old boy was admitted to our hospital with persistent high-grade fever, hepatomegaly, and pancytopenia. Laboratory data disclosed a coagulation abnormality and severe liver damage. Clonal proliferation of EBV-infected cells was detected in the bone marrow by Southern hybridization, and bone marrow cells exhibited clonal chromosomal abnormality. Although the patient was treated with immunochemotherapy according to the HLH94 protocol, the disease recurred during the induction therapy, and the patient died of disseminated intravascular coagulopathy. Considering this aggressive and fatal clinical course, it is important to take intensive therapeutic measures if karyotype abnormality is noted in the treatment of EBV-HLH patients.
    International Journal of Hematology 05/2000; 71(3):263-5. · 1.68 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: We report a case of myelodysplastic syndrome (MDS) with the 11q23 translocation at its leukemic transformation. Southern blot analysis demonstrated that the MLL gene on chromosome 11 was rearranged during the progression from MDS to acute leukemia. The clinical observation in this case supports the notion that leukemic transformation involves multiple cytogenetic evolutionary progresses, and that MLL gene rearrangement corresponds to the final step of leukemogenesis.
    International Journal of Hematology 02/1998; 67(1):23-6. · 1.68 Impact Factor
  • Source
    [show abstract] [hide abstract]
    ABSTRACT: The transcription factor NF-E2, a heterodimeric protein complex composed of p45 and small Maf family proteins, is considered crucial for the regulation of erythroid gene expression and platelet formation. To facilitate the characterization of NF-E2 functions in human cells, we isolated cDNAs encoding two members of the small Maf family, MafK and MafG. The human mafK and mafG genes encode proteins of 156 and 162 amino acid residues, respectively, whose deduced amino acid sequences show approximately 95% identity to their respective chicken counterparts. Expression of mafK mRNA is high in heart, skeletal muscle and placenta, whereas mafG mRNA is abundant in skeletal muscle and is moderately expressed in heart and brain. Both are expressed in all hematopoietic cell lines, including those of erythroid and megakaryocytic lineages. In electrophoretic gel mobility shift assays binding to NF-E2 sites was found to depend on formation of homodimers or heterodimers with p45 and p45-related CNC family proteins. The results suggest that the small Maf family proteins function in human cells through interaction with various basic-leucine zipper-type transcription factors.
    Oncogene 05/1997; 14(16):1901-10. · 7.36 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: Currently available data indicate that erythroid and megakaryocytic differentiation pathways are closely related to each other, and there may exist progenitor cells common to those two lineages may exist. Acute megakaryoblastic leukemia (AML-M7) and transient myeloproliferative disorder in Down's syndrome (TMD) are characterized by rapid growth of abnormal blast cells which express megakaryocytic markers. These blast cells express lineage-specific transcription factors such as GATA-1 common to these lineages and frequently express erythroid-specific mRNAs such as gamma-globin and erythroid delta-aminolevulinate synthase (ALAS-E), indicating that most of the blasts in M7 and TMD cases have erythroid and megakaryocytic phenotypes. These results suggest that blasts in M7 and TMD may correspond to progenitors of both erythroid and megakaryocytic lineages.
    Leukemia and Lymphoma 12/1996; 23(5-6):545-50. · 2.30 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: Transcription factor NF-E2 is crucial for regulation of erythroid-specific gene expression. p45 subunit of NF-E2 contains a basic-leucine zipper domain and dimerizes with the small Maf family protein to form functional NF-E2 complex. While p45 expression was shown to be restricted to erythroid cells, megakaryocytes and mast cells in hematopoietic lineage, we found in this study that p45 mRNA is abundantly transcribed in the granulocyte fraction of human peripheral blood cells. As neutrophils occupy approximately 92% of the cells in granulocyte fraction of human peripheral blood cells. As neutrophils occupy approximately 92% of the cells in this fraction, the cells expressing p45 is most likely to be neutrophils. p45 mRNA is also expressed in HL-60 promyelocytes, albeit the expression level is much lower than that of the granulocyte fraction. HL-60 cells were found to express mafK mRNA, indicating the presence of genuine NF-E2 complex in the cells. Although p45 mRNA is transcribed from two different promoters, aNF-E2 promoter and fNF-E2 promoter, in erythroid and megakaryocytic lineage cells, p45 mRNA is transcribed only from aNF-E2 promoter. The expression of p45 megakaryocytic lineage cells, p45 mRNA is transcribed only from aNF-E2 promoter. The expression of p45 mRNA in the neutrophils declined rapidly after transfer of the cells to in vitro culture and G-CSF could not sustain the expression from the down-regulation, suggesting the E2 may also participate in the regulation of neutrophil-specific gene expression.
    Biochemical and Biophysical Research Communications 03/1996; 219(3):760-5. · 2.41 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: Acute megakaryoblastic leukaemia (M7) and transient myeloproliferative disorder in Down's syndrome (TMD) are characterized by rapid growth of abnormal blast cells which express megakaryocytic markers. To clarify properties of the blast cells in M7 and TMD cases, we examined erythroid markers expression in blasts from six cases with M7 and seven cases with TMD in this study. Erythroid-specific mRNAs encoding gamma-globin and erythroid delta-aminolevulinate synthase were found to be expressed in blasts from most of these cases, indicating that majorities of the blasts in M7 and TMD cases have erythroid and megakaryocytic phenotypes. We also found that mRNAs encoding GATA-1 and GATA-2 are expressed in all these cases. These results suggest that M7 blasts and TMD blasts correspond to the erythroid/megakaryocytic bipotential progenitor cells.
    British Journal of Haematology 08/1995; 90(3):607-14. · 4.94 Impact Factor
  • British Journal of Haematology 05/1992; 80(4):561-3. · 4.94 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: A 7-year-old boy was admitted to our department complaining pale face and subcutaneous bleeding in August, 1987. Peripheral blood analysis showed pancytopenia of WBC 2,600/microliter, RBC 148 x 10(4)/microliter and platelets 5,000/microliter. Bone marrow biopsy revealed hypocellularity. Granulocytes 104/microliter, reticulocytes 4,290/microliter and platelets 5,000/microliter were compatible with the diagnosis of severe aplastic anemia based on the criteria of the Ministry of Public Welfare in Japan. Prednisolone (PDN) was initially indicated and bolus methylprednisolone, metenolone and ALG therapy followed with no hematological improvement. Fifteen months after admission, in addition to 0.5-1 mg/kg/day of metenolone, Cyclosporin A (CyA) was started at a dose of 12 mg/kg/day for a week and 6 mg/kg/day thereafter. After a week from administration of CyA, 1 mg/kg/day of PDN was given because his bleeding tendency became worse. But this combination was complicated with liver damage and hyperglycemia to discontinue both drugs. These adverse effects were subsided within 7 days by cessation of the drugs. CyA was started again at a dose of 6 mg/kg/day without any response for 4 weeks. Then PDN was added together at a reduced dose of 0.5-1 mg/kg/day. Hematological response was obtained promptly. Granulocytes reached 1,500/microliter, hemoglobin 10.2 g/dl and platelets 26,000/microliter after 3 months of therapy. Afterward the patient became transfusion independent. The most effective method of CyA administration for aplastic anemia is still controversial. Alternative use of CyA, considering combination of steroids or anabolic steroids, in patients who failed to respond to conventional immunosuppressive treatments should be further investigated.
    [Rinshō ketsueki] The Japanese journal of clinical hematology 01/1990; 30(12):2157-62.