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T Osato

Publications and source records attributed to T Osato.

156 records · Page 9Linked to original sources
PubMedDate not supplied

Appearance of Epstein-Barr virus-determined nuclear antigen in human epithelial cells following fusion with lymphoid cells.

When human epithelial FL cells were fused with lymphoid cells harboring Epstein-Barr virus (EBV) genome, EBV-determined nuclear antigen (EBNA) immunofluorescence became evident in high frequency in FL nuclei of heterokaryons several days after fusion. The implications of the findings are discussed in relation to the presence of EBV genome in nasopharyngeal carcinoma cells.

Amnion↗
PubMedDate not supplied

Suppression by protein kinase C inhibitors of tumor promoter enhancement of Epstein-Barr virus-induced growth transformation.

The tumor promoter teleocidin activates latent Epstein-Barr virus (EBV) genomes and enhances EBV-induced growth transformation of human B cells, with an activity comparable to that of 12-O-tetradecanoyl-phorbol-13-acetate (TPA). It has been suggested that the TPA induction of EBV genomes is mediated by protein kinase C (PKC), an enzyme closely linked to signal transduction. We examined newly isolated, highly selective PKC inhibitors, UCN-01 (7-hydroxyl-staurosporine) and calphostin C, for the possible suppression of teleocidin enhancement of cord blood B lymphocyte growth transformation by EBV. 0.2 nM teleocidin B4 enhanced EBV-induced 3H-thymidine uptake 6 times, outgrowth in limiting dilution culture 5 times, and colony formation in semisolid agar 3 times. All these events were suppressed by exposure to 10-100 nM UCN-01 or to calphostin C. Our findings suggest that the tumor promoter enhancement of EBV growth transformation is probably mediated by PKC.

Alkaloids↗
PubMedDate not supplied

Prevalence of human T-cell leukemia virus type 1 (HTLV-I) in family members of adult T-cell leukemia (ATL) patients in non-ATL-endemic Hokkaido of Japan.

Family members of patients with adult T-cell leukemia (ATL) in non-ATL-endemic Hokkaido, the northernmost part of Japan, were assessed for the prevalence of HTLV-I infection. Immunofluorescence assay showed that 53 out of 133 (39.8%) healthy family members of 23 ATL patients were positive for antibodies to HTLV-I. When general inhabitants in Hokkaido were examined, 3 out of 18 (16.7%) family members of 5 seropositive healthy persons had HTLV-I antibodies. The overall seropositivity in Hokkaido was 0.7%. Of 26 family members of 6 patients with non-T-cell leukemia seroconverted by blood transfusion, none (0%) was seropositive.

Adolescent↗
PubMedDate not supplied

Prevalence of human T-cell leukemia virus type 1 (HTLV-I) in adult T-cell leukemia (ATL) in non-ATL-endemic Hokkaido of Japan.

Sera and peripheral blood lymphocytes of 40 adult T-cell leukemia (ATL) patients in non-ATL-endemic Hokkaido were examined for the prevalence of human T-cell leukemia virus type 1 (HTLV-I). All patients had HTLV-I-specific antibodies. When the peripheral lymphocytes were assessed after short-term cultivation, HTLV-I antigens and virus particles were detected. The seroprevalence in 96 cases of non-T-cell leukemias and lymphomas and in 30,056 healthy individuals in Hokkaido were 3.1% and 0.7%, respectively. HTLV-I seropositive inhabitants of Hokkaido can be estimated at about 40,000, and one out of every few thousand HTLV-I carriers is likely to develop ATL.

HTLV-I Antibodies↗
PubMedDate not supplied

Prevalence of human T-cell leukemia virus type 1 (HTLV-I) in general inhabitants in non-adult T-cell leukemia (ATL)-endemic Hokkaido, Japan.

In contrast to adult T-cell leukemia (ATL)-endemic southwestern Japan, the northernmost island Hokkaido has a small number of ATL patients annually. In this study, we surveyed 32,587 healthy inhabitants throughout Hokkaido for antibodies to human T-cell leukemia virus type 1 (HTLV-I). Only 244 individuals (0.8%) were seropositive as HTLV-I carriers; 0.6% (123 of 19,512) in males and 0.9% (121 of 13,075) in females. In some areas, however, the inhabitants had relatively high seropositivity (> 2%). The highest rate was 5.2% with a cluster of ATL patients in a certain town of the Hidaka area near the Pacific Ocean, in southeast Hokkaido.

Adolescent↗
PubMedDate not supplied

Cryptic dysfunction of cellular immunity in asymptomatic human immunodeficiency virus (HIV) carriers and its actualization by an environmental immunosuppressive factor.

Peripheral blood lymphocytes from 4 asymptomatic HIV-1 carriers with normally retained EBV-specific cytotoxic T-cell activity were exposed to EBV and incubated with 0.2 ng/ml 4-deoxyphorbol ester, an immunosuppressive substance derived from an African plant Euphorbia tirucalli. The regression of EBV-induced B-cell transformation by EBV-specific cytotoxic T-cells was significantly impaired in the presence of a small amount of 4-deoxyphorbol ester, but not so in 5 HIV-1-seronegative healthy counterparts. When the EBV-specific cytotoxic T-cells from the asymptomatic carriers were exposed to 0.2ng/ml 4-deoxyphorbol ester and incubated with 51Cr-labeled autologous EBV-transformed B lymphocytes, the released radioactivity was significantly smaller than that of the healthy counterparts. The results suggest that the cellular immunity of the asymptomatic HIV-1 carriers is cryptically impaired, and the cryptic immunological dysfunction is actualized by exposure to a small amount of the immunosuppressive substance, a dose which does not affect the immunity of uninfected healthy individuals.

Adolescent↗
PubMedDate not supplied

African Burkitt's lymphoma: a plant, Euphorbia tirucalli, reduces Epstein-Barr virus-specific cellular immunity.

Endemicity of Burkitt's lymphoma (BL) coincides with profusion of a plant Euphorbia tirucalli in tropical Africa. E. tirucalli contains 4-deoxyphorbol ester that enhances Epstein-Barr virus (EBV) infection of B lymphocytes. In this study, we found that 4-deoxyphorbol ester reduced EBV-specific cytotoxic T-cell function. Furthermore, the B lymphocytes dually exposed to EBV and 4-deoxyphorbol ester were resistant to EBV-specific T cell cytotoxicity, through down-regulation of latent membrane protein 1 (LMP1), the major target to EBV-specific cytotoxic T-cells. These immunologic findings strengthen the notion that E. tirucalli may be an important environmental risk factor for the genesis of African BL.

Africa↗