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Biomedical subjects

M Tomonaga

Publications and source records attributed to M Tomonaga.

At least 37 records · Page 2Linked to original sources
PubMed2001

HTLV-1 proviruses encoding non-functional TAX in adult T-cell leukemia.

Adult T-cell leukemia (ATL) is associated with prior infection with human T-cell leukemia virus type 1 (HTLV-1). TAX, the major transactivator of HTLV-1, has been implicated in the immortalization of infected T-cells, but molecular mechanisms of in vivo malignant cell transformation induced by HTLV-1 remain unclear. To investigate the role of TAX in the monoclonal proliferation of ATL cells, we determined the nucleotide sequence of tax DNA clones obtained from 6 ATL patients and analysed the biological function of their products. We found that ATL cells from 2 of these patients possessed tax with a nonsense or frame-shift mutation resulting in the premature termination of its protein product, which was no longer functional. This strongly argued against an indispensable role of TAX for the maintenance of ATL cells in vivo. On the other hand, the frequency of nucleotide substitutions found in non-functional tax DNA clones from these patients was significantly lower than those in functional tax DNA clones from the others, suggesting a role for TAX in the genome instability of infected cells. Although mismatch repair defects in the microsatellite markers, including those in hMSH3, hMSH6, BAX, TGF-beta RII, and E2F4 genes, were infrequent, we found an increase in the number of CAG repeats of the E2F4 microsatellite marker in 1 patient. These findings indicate that while TAX may be a necessary prerequisite for malignant transformation of infected cells, it is not essential for the maintenance of ATL cells in vivo.

Aged↗
PubMed2001

Improved outcome of adult T cell leukemia/lymphoma with allogeneic hematopoietic stem cell transplantation.

Adult T cell leukemia/lymphoma (ATL) is a poor prognosis T cell malignancy. In order to improve the outcome, we employed allogeneic stem cell transplantation (allo-SCT) for ATL in 10 patients, nine of whom were from HLA-identical siblings and one from an unrelated donor. Conditioning regimens varied among the patients except that all received total body irradiation. The patients tolerated the regimens well with mild, if any toxicity, and engraftment occurred in all cases. Median leukemia-free survival after allo-SCT was 17.5+ months (range 3.7-34.4+). Six of the 10 patients developed acute GVHD (one case each with grade I, III or IV, and three cases with grade II) and three patients developed extensive chronic GVHD. Four patients died after allo-SCT during the study period from either acute GVHD (grade IV), pneumonitis, gastrointestinal bleeding or renal insufficiency. Two of the 10 cases with no symptoms of GVHD relapsed with clinical ATL. These results strongly suggest that allo-SCT may improve the survival in ATL if a controlled degree of GVHD develops.

Adult↗
PubMed2001

Effect of a selective Abl tyrosine kinase inhibitor, STI571, on in vitro growth of BCR-ABL-positive acute lymphoblastic leukemia cells.

By employing a new semi-quantitative assay system that includes co-culturing leukemia cells with the mouse bone marrow-derived stromal cell line MS-5, we examined the suppressive effect of a selective inhibitor of ABL tyrosine kinase, STI571, on acute lymphoblastic leukemia (ALL) cells with BCR-ABL fusion. Leukemic blast cells from eight patients with B-precursor ALL, including three patients with BCR-ABL-positive ALL, were cultured on monolayers of MS-5 cells for 3 weeks with or without addition of variable amounts of STI571. In all cases, cobblestone areas (CAs) were formed, showing clear linear cell dose-dependent curves, allowing quantitative assessment of blast cell growth. The progenitor frequencies obtained by this direct CA-forming cell (CAFC) assay were equivalent to ALL progenitor frequencies assessed by the standard limiting dilution assay. The number of CAFCs ranged from 12.3 to 140.3/10(4) cells. In BCR-ABL-positive ALL patients, CA-containing cells were examined by FISH, and all contained BCR-ABL fusion genes. STI571 inhibited CA formation of BCR-ABL-positive ALL cells virtually 100% at 0.1-1.0 micromol/l. None of the five BCR-ABL-negative ALL patients showed this growth inhibition by STI571 at 0.1-1.0 micromol/l. Our results indicate that STI571 selectively inhibits in vitro growth of BCR-ABL-positive ALL cells.

Adolescent↗
PubMed2001

A new G-CSF-supported combination chemotherapy, LSG15, for adult T-cell leukaemia-lymphoma: Japan Clinical Oncology Group Study 9303.

This phase II trial was performed to evaluate the efficacy of a new granulocyte colony-stimulating factor (G-CSF)-supported multi-agent chemotherapy protocol, LSG15, for aggressive adult T-cell leukaemia-lymphoma (ATL). Ninety-six previously untreated patients with aggressive ATL were enrolled and grouped as: acute type (58), lymphoma type (28) and unfavourable chronic type (10). Therapy consisted of seven cycles of VCAP (vincristine, cyclophosphamide, doxorubicin and prednisone), AMP (doxorubicin, ranimustine and prednisone) and VECP (vindesine, etoposide, carboplatin and prednisone). G-CSF was administered during the intervals between chemotherapy until neutrophil reconstitution was achieved. Eighty-one per cent of the 93 eligible patients responded [95% confidence interval (CI), 71.1-88.1%], with 33 patients obtaining complete response (35.5%) and 42 obtaining partial response (45.2%). The median survival time (MST) after registration was 13 months and the median follow-up duration of the 20 surviving patients was 4.2 years (range 2.8-5.6). Overall survival at 2 years was estimated to be 31.3% (95% CI, 22.0-40.5%). Grade 4 haematological toxicity of neutropenia and thrombocytopenia were observed in 65.3% and 52.6% of the patients respectively, but grade 4 non-haematological toxicity was observed in only one patient. LSG15 is feasible with mild non-haematological toxicity and improved the clinical outcome of ATL patients. MST and overall survival at 2 years were superior to those obtained by our previous trials.

Adult↗
PubMed2001

Aberrant expression of caspase cascade regulatory genes in adult T-cell leukaemia: survivin is an important determinant for prognosis.

Derangement of either apoptosis or cell division is known to play an important role in tumorigenesis. Fas-mediated apoptosis on normal and leukaemic T cells is finely tuned by inhibitory proteins, such as FAP-1, FLIP and survivin, and defective caspase isoform which can attenuate the function of its intact caspase as a decoy molecule. However, complex involvement of such inhibitors in tumour biology relating to apoptotic pathology remains unclear in the neoplasms. We report the aberrant expression of FAP-1, FLIP and survivin mRNAs on leukaemic T cells from adult T-cell leukaemia (ATL) patients. Among these inhibitors, only survivin was aberrantly expressed in all ATL cases, but not in any normal peripheral blood mononuclear cells (PBMCs). Furthermore, survivin mRNA expression level was characteristic in each subtype of ATL and represented an important determinant for ATL prognosis. However, the apoptotic effector of casp-8, which is essential in Fas-mediated signal transduction, was dominant in defective casp-8 rather than intact casp-8 in ATL cells, suggesting a favourable biological situation for escape from apoptosis. Taken together, ATL cells probably possess many different regulatory mechanisms in order to attenuate Fas-mediated signalling and subsequently expand their populations under escape from apoptosis. Among these inhibitors, survivin is a useful bio-marker to assess tumour biology and may be a potential new target for apoptosis-based selective therapy in neoplasms as the expression is a general feature of neoplasia, but not normal tissues.

Apoptosis↗
PubMed2001

Expression of nuclear factor kappaB and tumor necrosis factor alpha in the mouse brain after experimental thermal ablation injury.

OBJECTIVE: Nuclear factor kappa B (NFkappaB) participates in the regulation of a diverse range of genes involved in inflammation and acute phase responses. We investigated the expression of the activated form of NFkappaB and tumor necrosis factor alpha (TNFalpha), an inflammatory cytokine, in experimental brain injury. METHODS: We generated focal brain injury in mice using radiofrequency thermal ablation at the caudate putamen in mice. Intracerebral expression of TNFalpha and the p50 and p65 subunits of NFkappaB were studied using immunohistochemistry at 1, 4, and 8 hours and at 1, 2, 4, 8, 14, and 28 days postinjury. RESULTS: Coagulative necrosis approximately 2 mm in diameter was produced at the site of injury. No immunoreactivity for TNFalpha, NFkappaB p50, or NFkappaB p65 was detected in the injured area in the early phase postinjury. On posttrauma Day 2, however, weak expression of TNFalpha, NFkappaB p50, and NFkappaB p65 was detected in mononuclear cells that infiltrated edematous tissue surrounding the lesion. On posttrauma Days 4 to 8, the expression of TNFalpha, NFkappaB p50, and NFkappaB p65 was prominently increased in infiltrating and proliferating mononuclear cells (macrophages and microglia) and in proliferating reactive astrocytes surrounding the lesion. Nuclear subcellular localization of the expression of NFkappaB p50 and p65 was observed, which indicated that these subunits might be activated in these cells. On posttrauma Day 14, the expression of TNFalpha, NFkappaB p50, and NFkappaB p65 decreased and was limited to mononuclear cells, and it finally disappeared on Day 28. The temporal profiles of TNFalpha, NFkappaB p50, and NFkappaB p65 were closely associated with the occurrence of secondary insults and the tissue-remodeling process in wound healing. CONCLUSION: These results suggest that TNFalpha, NFkappaB p50, and NFkappaB p65 may play a central role in the injury-induced immune response that leads to secondary insults or wound healing after brain injury. Inappropriate and deregulated activation of NFkappaB in injured brain tissue may be implicated in the development of secondary brain damage.

Animals↗
PubMed2001

Possible involvement of interferon regulatory factor 4 (IRF4) in a clinical subtype of adult T-cell leukemia.

Interferon regulatory factor (IRF) 4 is the lymphoid-specific transcription factor that is required for the proliferation of mitogen-activated T cells. IRF4 has been suggested to be involved in tumorigenesis because the overexpression of IRF4 caused the transformation of Rat-1 fibroblasts in vitro. Here, we show that IRF4 is constitutively expressed in adult T-cell leukemia (ATL)-derived cell lines, which were infected with human T-cell leukemia virus type-I, but hardly expressed the trans-activator protein, Tax. Similarly, constitutive expression of IRF4 was demonstrated in freshly isolated peripheral blood mononuclear cells (PBMC) from patients with either acute or chronic ATL. However, the high-level expression of IRF4 was specifically associated with acute ATL. With mitogen-activated PBMC from healthy donors, cell cycle analyses revealed that the induction of IRF4 occurred prior to cell cycle progression and the cells that had entered the cell cycle were predominantly IRF4-positive cells. In addition, ectopic expression of IRF4 in Rat-1 fibroblasts increased the S and G2 / M phase population significantly. Taken together, our results indicate that IRF4 is involved in the pathogenesis of ATL through its positive effect on the cell cycle, and that IRF4 can be used as a molecular marker of clinical subtype in ATL.

Adult↗
PubMed2001

[New classification of leukemia].

By keeping a cytomorphological basis for the diagnosis of leukemia according to the FAB classification, a new classification system was proposed by the WHO group, which incorporated four genetically established entities of acute leukemia. This classification also made some changes in MDS categories and provided new criteria for diagnosing acute myeloid leukemia. Combined use of this classification with the FAB classification will promote investigations into leukemia.

Humans↗
PubMed2001

[Effects of preserved erythrocytes and activated-preserved erythrocytes with phosphoenolpyruvate on energy metabolism in rat ischemic brain tissue].

The effects of erythrocyte function on cerebral ischemia were studied from the perspective of filtration capability (deformability) and total oxygen delivery. Erythrocytes of Wistar rats were divided into three groups: fresh blood, preserved blood, and activated preserved blood (preserved erythrocytes in which total oxygen delivery was increased with phosphoenolpyruvate). Filtration capability was calculated and evaluated by a filtration technique, while total oxygen delivery was evaluated by calculating the efficiency of oxygen delivery from an oxygen dissociation curve. Exchange transfusion was performed in spontaneously hypertensive rats with each of these groups at the same hemoglobin concentration. Bilateral carotid arteries were then ligated for one hour, and, cerebral blood flow and concentrations of adenine nucleotide and lactic acid in cerebral tissue were measured. The filtration capability of both preserved blood and activated preserved blood decreased to about one-third that of fresh blood. The efficiency of oxygen delivery after blood transfusion decreased to 17% with preserved blood, which was about half that (35%) with fresh blood. In the group of with activated preserved blood, this rate increased to 52%. The adenylate energy charge (E.C.) in brain tissue markedly decreased to 0.27 with preserved blood, which was much lower than the value (0.74) with fresh blood. With activated preserved blood, the E.C. value was 0.39. Thus, the decrease in E.C. was mild. With regard to the lactic acid concentration in brain tissue, the value with fresh blood was 12 mumoles/g tissue, while that with preserved blood was 24 mumoles/g tissue, and that with activated preserved blood was 18 mumoles/g tissue. With respect to cerebral blood flow, the values with preserved blood and activated preserved blood decreased to about one-half that with fresh blood. These results suggest that an increase in total oxygen delivery by erythrocytes contributes to improving energy metabolism in brain tissue during cerebral ischemia, and particularly during poor microcirculation.

Animals↗
PubMed2001

Vascular endothelial growth factor and cellular chemotaxis: a possible autocrine pathway in adult T-cell leukemia cell invasion.

Our previous report (T. Hayashibara et al., Leukemia, 13: 1634-1635, 1999) revealed a possible link between high plasma vascular endothelial growth factor (VEGF) concentration and leukemic cell invasion in adult T-cell leukemia (ATL). However, the biological mechanism of this link has not been elucidated. The purpose of this study was to address that mechanism. Our present observations showed that VEGF mRNA was expressed in ATL cell lines. The corresponding protein was secreted into the extracellular environment, which suggested that the major source of plasma VEGF is ATL cells themselves. More interestingly, all of the cell lines examined were found to express the mRNA and protein for fms-like tyrosine kinase-1 (Flt-1), which is one of the receptors for VEGF. Cytofluorometric analysis demonstrated the VEGF binding potency of these cells. In clinical specimens, expression of VEGF and Flt-1 mRNAs was detected in all (100%) of 11 and 8 (73%) of 11 ATL patients, respectively. Cytofluorometric analysis revealed that VEGF effectively bound only to Flt-1-expressing cells. These findings are highly suggestive of an autocrine pathway involving VEGF operating in ATL. The proliferation of ATL cell lines was not affected by treatment with an anti-VEGF antibody or exogenous VEGF, which indicated that VEGF has no mitogenic effect on ATL cells. In contrast, we made the interesting finding that treatment with exogenous VEGF enhanced the chemotactic activities of some ATL cell lines, which may play a key role in ATL cell invasion. Collectively, these data lead us to propose a possible autocrine mechanism involving VEGF operating by way of Flt-1, in which ATL cells up-regulate their own chemotaxis to facilitate their invasion into various organs.

Adult↗
PubMed2001

Evaluation of a telemedicine system for supporting thyroid disease diagnosis.

A telemedicine system connecting Japan and Belarus via a communication satellite and the international ISDN has been in use since February, 1999. Two relational databases, which are essentially the same, are set respectively at Nagasaki University School of Medicine and Gomel Regional Specialized Dispensary in Belarus for management of patients' data and for research including epidemiologic studies. The thyroid ultrasonographic images, microscopic images of cytological findings and other information on patients are sent from Gomel to Nagasaki once a week with diagnoses and comments by physicians at Gomel Regional Specialized Dispensary for cases whom they found difficult to diagnose. Thyroid specialists at Nagasaki University School of Medicine correct the diagnoses, if necessary, on the basis of information from Gomel and send their comments and instructions to Gomel for improving diagnosis skills of physicians at Gomel. The findings of 330 cases have been sent from Gomel to Nagasaki by September, 2000 since the commencement of the system in February, 1999. Of the 329 cases, thyroid diagnosis was made at Gomel for 261 cases in whom two or more diagnoses were made for 35 cases. As of the end of October, 2000, the Gomel diagnoses have been reviewed for 217 cases and the remaining 112 cases are under review at Gomel. The diagnoses made at Gomel and Nagasaki were in agreement for 110 (50.7%) of 217 cases. Thyroid cancer was diagnosed in 8 cases in whom 6 had been diagnosed at Gomel while the other 2 were diagnosed anew at Nagasaki. The usefulness of the system for improving thyroid diagnosis in Belarus was indicated.

Databases, Factual↗
PubMed2001

[Chemotherapy and radiation therapy].

Stem cell transplantation and interferon-based treatment are major strategies in chronic phase CML and chemotherapy is one of limited therapeutic options when they are not available or ineffective. Hydroxyurea is superior to busulfan in better effect and lesser side effects. Homoharringtonine, a plant alkaloid, has shown cytogenetic response in one third of patients who were resistant to interferon therapy, and a better response rate in combination with cytarabine and interferon alfa. There have been no improvement of clinical outcome in treatment of accelerated phase and blastic crisis although many trials including decitabine are going on.

Antimetabolites, Antineoplastic↗
PubMed2000

Identification of a novel cytokine response element in the human IFN regulatory factor-1 gene promoter.

The present study investigates the regulatory mechanisms involved in the cooperation between IFN-gamma and TNF-alpha to promote transcription from IFN regulatory factor-1 (IRF-1). A transient transfection analysis revealed that the region between -218 and -144, where +1 is the transcription start site, as well as previously reported downstream elements, ppkappaB and IFN-gamma activation site/kappaB, were required for the optimal response to the two cytokines. A subsequent DNase I footprint analysis showed that the region between -171 and -144 was inducibly protected with stimulation by TNF-alpha, and this protection was significantly enhanced with the combination of IFN-gamma and TNF-alpha. In an EMSA with the protected region as a probe, a TNF-alpha-inducible complex (C1) and an IFN-gamma-inducible complex (C2), but no synergy-specific DNA-protein complexes, were recognized. The C1 complex consisted of a pre-existing factor (p65/p50), whereas the C2 complex consisted of a newly synthesized IRF-1-related factor. A methylation interference assay revealed the critical G residues (from -167 to -151) for the DNA-protein complex formation specific to the cytokine response, and within this region the novel kappaB sequence, the promoter distal kappaB (pdkappaB) element (5'-GGGGAAG TAC-3'), was identified. Because the base substitutions over the pdkappaB region (from -171 to -144) affected not only the TNF-alpha-response but also that of IFN-gamma, this region might contribute to the cooperative action of the NF-kappaB subunits with the IRF-1-related factor. Finally, we demonstrated that none of the cis-acting elements, ppkappaB, pdkappaB, or IFN-gamma activation site/kappaB, is dispensable for the optimal synergism in response to IFN-gamma and TNF-alpha.

Adjuvants, Immunologic↗