Biomedical subjects

Hiroaki Morimoto

Publications and source records attributed to Hiroaki Morimoto.

7 recordsLinked to original sources

PubMed2005

Reduced expression of human mismatch repair genes in adult T-cell leukemia.

In this study, we investigated the expression of six human DNA mismatch repair (MMR) genes, human MutS homologues 2 (hMSH2), 3 (hMSH3), and 6 (hMSH6), human MutL homologue 1 (hMLH1), human post-meiotic segregations 1 (hPMS1) and 2 (hPMS2), in primary leukemic cells obtained from 11 patients with acute-type adult T-cell leukemia (ATL) by using reverse transcription-polymerase chain reaction (RT-PCR). In contrast to normal peripheral lymphocytes, all primary ATL samples had reduced or loss of expression of two or more MMR genes, and the expression of several MMR genes was simultaneously suppressed in each ATL patient. Abnormal expression of hMSH2, hMSH3, hMSH6, hMLH1, and hPMS1 was observed more frequently than that of hPMS2. In particular, expression of hMSH2 and hPMS1 was reduced in all cases. Western blot analysis further showed reduced expression of both hMSH2 and hPMS1 proteins in all five cases examined. In three out of the 5 cases, both of the two proteins were undetectable. Interestingly, methylation-specific PCR indicated methylation of hPMS1 promoter in all of four ATL cases examined. hPMS1 expression, but not hMSH2 expression, was restored by treatment with a DNA demethylation agent, 5-aza-2'-deoxycytidine, suggesting that methylation plays a crucial role in inhibition of the hPMS1 gene expression in ATL. Our results demonstrate that defect of both human MutS and human MutL systems in primary ATL cells.

Adaptor Proteins, Signal Transducing↗

PubMed2005

Constitutive tyrosine and serine phosphorylation of STAT4 in T-cells transformed with HTLV-I.

STAT4 is a critical mediator of IL-12-stimulated gene regulation in T-helper type 1 (Th1) cell. IL-12 activates the Janus family tyrosine kinases JAK2 and Tyk2, which in turn phosphorylate STAT4 on tyrosine 693. The p38 mitogen-activated protein kinase (MAPK) signaling pathway is also activated in response to IL-12, followed by phosphorylation of STAT4 on serine 721, which is required for STAT4 full transcriptional activity. In the present study, we demonstrated constitutive activation of STAT4 in HTLV-I-transformed T-cell lines MT-2, MT-4 and HUT102 by immunoprecipitation, Western blotting and electrophoretic mobility shift assay (EMSA). In HTLV-I-transformed T-cell lines, STAT4 was constitutively phosphorylated not only on tyrosine 693 but also on serine 721, and formed a heterodimer with STAT3. Constitutive phosphorylation of its upstream activators, JAK2, Tyk2 and p38 MAPK was also observed in the cells. EMSA and transient transfection studies further showed that the high-affinity sis-inducible element (hSIE) preferentially binds the STAT3/STAT4 heterodimer and is constitutively transactivated in MT-2 cells in the absence of exogenous cytokine stimulation. When STAT4 expression vector was cotransfected along with STAT3 expression vector into MT-2 cells, STAT4 significantly synergized with STAT3 to transactivate hSIE, showing the functional importance of heterodimer formation between STAT4 and STAT3.

Blotting, Western↗

PubMed2005

[Generalized erythema triggered by a rapid decrease of basophils in chronic myeloid leukemia treated with imatinib].

A 57-year-old woman with chronic myeloid leukemia showing severe basophilia (WBC 17.1 X 10(9)/L, basophils 23%) was treated with 400mg imatinib in June 2003. A high basophil count (WBC 10.6 X 10(9)/L, basophils 31%) was still observed after 1 week of therapy. After 9 days of therapy, she developed generalized pruritic skin erythema, chills and high fever. After terminating imatinib treatment, prednisolone therapy was initiated. The rash quickly disappeared. Four days after withdrawal of imatinib, leukocyte count was 13.0 X 10(9)/L with 3% of basophils, suggesting the possibility that rapid decrease in basophils following imatinib therapy may induce severe cutaneous reactions.

Antineoplastic Agents↗

PubMed2005

[Angioimmunoblastic T-cell lymphoma accompanied by pure red cell aplasia].

A 71-year-old woman was admitted in December 2002 because of lymphadenopathy, hepatosplenomegaly and pleural effusion. She had severe anemia with hemoglobin 5.9 g/dl and a reticulocyte count of 1% per hundred. Direct/indirect Coombs tests and anti-double stranded DNA antibody were positive, her serum CH50 level was reduced and an increase in serum LDH isoenzyme 3 was observed. Bone marrow aspiration showed an almost total absence of erythroblasts and no pathological cell proliferation. The diagnosis of angioimmunoblastic T-cell lymphoma (AILT) was made based on the lymph node histological findings. Proliferation of arborizing small vessels with hyperplastic endothelium and infiltration of atypical T-lymphocytes were observed. After combination chemotherapy (THP-COP), remission was achieved in both the pure red cell aplasia (PRCA) and AILT. Remission was also accompanied by normalization of the Coombs tests, suggesting that autoimmune mechanisms in AILT may contribute to the development of PRCA.

Aged↗

PubMed2004

Imatinib mesylate-sensitive blast crisis immediately after discontinuation of imatinib mesylate therapy in chronic myelogenous leukemia: report of two cases.

Although imatinib mesylate has shown encouraging activity in chronic myelogenous leukemia (CML), disease progression during therapy has been observed, manifested by clonal expansion of imatinib mesylate-resistant leukemia cells. On the other hand, myelosuppression related to treatment of imatinib mesylate is often managed with temporary interruption of treatment or dose reduction. We here report two CML patients who had imatinib mesylate-sensitive blast crisis (BC) immediately after discontinuation of imatinib mesylate therapy. The patients discontinued therapy because of neutropenia. Although there was no evidence of blastic phase during therapy, BC occurred 2 weeks after the withdrawal of treatment in both cases. Interestingly, additional chromosomal abnormalities were detected following the withdrawal of imatinib mesylate and disappeared by re-introduction of this agent. The same doses of imatinib mesylate was still effective and remission was sustained with imatinib mesylate alone again. Our report suggests the possibility that withdrawal of imatinib mesylate may lead to proliferation of blast clones even in patients showing good responses to imatinib mesylate without signs of disease progression.

Aged↗

PubMed2004

[Remission induction of refractory diffuse large B-cell lymphoma with allogeneic peripheral blood stem cell transplantation followed by interferon-alpha and donor lymphocyte infusion].

Graft-versus-lymphoma (GVL) effect has been described in patients with malignant lymphoma after allogeneic stem cell transplantation (alloSCT). The effect of interferon-alpha (IFN-alpha) on the GVL effect still remains unclear. Here we report on a 29-year-old woman with refractory diffuse large B-cell lymphoma (DLBL). Her clinical findings included multiple masses in the liver, stomach, bilateral kidneys, thyroid, vertebral bones and a bulky mediastinal mass. Since the patient did not respond to various combination chemotherapies and further developed superior vena cava syndrome, allogeneic peripheral blood stem cell transplantation (PBSCT) from a HLA-identical brother was carried out after a myeloablative TBI/CY-based conditioning regimen. DLIs have been also performed every 4 weeks since day +14. As a result, the lymphoma masses showed a partial response. In order to enhance the GVL effect, IFN-alpha was further given at a maximum of 3 MU four times per week. Although the patient only experienced graft-versus-host disease of the skin (grade II) even after both DLIs and IFN, complete clinical remission was observed. 200 days after transplantation, the patient is still disease-free and in good condition. This report suggests the curative potential of IFN-alpha combined with DLI after allogeneic SCT in refractory DLBL.

Adult↗

PubMed2003

Experimental proof of contamination of blood components by (1-->3)-beta-D-glucan caused by filtration with cellulose filters in the manufacturing process.

The level of (1-->3)-beta-D-glucan in blood is a diagnostic index of fungal infection because it is released from the fungal cell wall. However, high levels of plasma (1-->3)-beta-D-glucan in patients administered blood components may give false positive results. High levels of (1-->3)-beta-D-glucan have been detected in blood components. We suspected that (1-->3)-beta-D-glucan from cellulose filters had been eluted into blood components by filtration in the manufacturing process. To investigate the contamination of blood components by (1-->3)-beta-D-glucan from cellulose filters, in vitro experiments were performed by using six cellulose filters and a nylon filter. Human serum albumin (HSA) solution (100 ml) was flowed through each filter after rinsing with 100 ml of distilled water, and (1-->3)-beta-D-glucan in each fraction was determined by Fungitec G test MK. The concentration of (1-->3)-beta-D-glucan eluted from cellulose filters in 100-ml distilled water fractions ranged from 6 to 207 pg/ml, and that of HSA fractions ranged from 33 to 20,784 pg/ml. These data showed that remarkably higher (1-->3)-beta-D-glucan levels were detected in HSA fractions flowed through cellulose filters in spite of advance rinsing with 100 ml of distilled water. In the case of a nylon filter, (1-->3)-beta-D-glucan was not eluted in either fraction. These results indicate that (1-->3)-beta-D-glucan contamination in blood components is caused by filtration with cellulose filters in the manufacturing process.

Blood Chemical Analysis↗