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Biomedical subjects

S Orita

Publications and source records attributed to S Orita.

At least 55 records · Page 3Linked to original sources
PubMed1993

Identification of novel singly spliced pX mRNA transcripts common to all human T-cell leukemia virus type 1-related retroviruses.

Human T-cell leukemia virus type 1 (HTLV-1) and its related viruses, that is, human T-cell leukemia virus type 2 (HTLV-2), simian T-cell leukemia virus (STLV), and bovine leukemia virus (BLV), encode a doubly spliced pX mRNA transcript in addition to the singly spliced env and unspliced gag-pol mRNAs common to the prototypic simple retroviruses, such as murine and avian leukemia viruses. In HTLV-1-infected cells, we recently identified the novel singly spliced pX mRNA responsible for expressing the smaller rex gene product, p21X. In the present study we demonstrate that the novel singly spliced pX mRNA is also expressed in cells infected with HTLV-2, STLV, and BLV, respectively. This finding indicates that all members of the HTLV-1-related virus group have the common ability to express the singly spliced pX mRNA. This novel mRNA in the HTLV-1-related virus group may be analogous to the two-exon nef specific mRNA in human immunodeficiency virus type 1.

Animals↗
PubMed1993

Tyzzer's disease complicated with distemper in a puppy.

A Pomeranian puppy which died from diarrhea and nasal discharge showed catarrhal pneumonia, acute enteritis and focal liver necrosis. Slender bacilli were detected within ileal enterocytes and hepatocytes. A double infection with a distemper virus and Tyzzer's organism at a cellular level was seen within the ileal enterocytes.

Animals↗
PubMed1992

Strong induction of ICAM-1 in human T cells transformed by human T-cell-leukemia virus type 1 and depression of ICAM-1 or LFA-1 in adult T-cell-leukemia-derived cell lines.

Sixteen human T-cell lines were studied for the expression of a cell-adhesion molecule ICAM-1 and its counter-receptor LFA-1. The cell lines included 3 human T-cell-leukemia-virus-type-I (HTLV-1)-negative cell lines derived from acute lymphoblastic leukemia (ALL) and 13 HTLV-1-positive cell lines, 7 of them established from cord- or peripheral-blood T cells by in vitro transformation with HTLV-1, 2 derived from HTLV-1 carriers, and 4 derived from patients with adult T-cell leukemia (ATL). In sharp contrast to a basal level of ICAM-1 in 3 HTLV-1-negative ALL cell lines, strong induction of ICAM-1 was seen in all HTLV-1-positive T-cell lines except for MT-1, one of the 4 ATL cell lines used in the present study. On the other hand, the expression of LFA-1 (CD11a and CD18) was more or less similar among the cell lines with and without HTLV-1. Interestingly, however, 3 out of 4 ATL cell lines (TL-Om1, H582, HUT102) revealed striking depression of LFA-1 expression. Several lines of evidence strongly argued against direct involvement of the viral transactivator p40tax or some autocrine cytokines in the induction of ICAM-1 in HTLV-1-positive T-cell lines. It was also found that ICAM-1 and LFA-1 were involved in syncytium formation induced in the co-culture of HTLV-1-positive and HTLV-1-negative human T-cell lines. Implications of constitutive expression of ICAM-1 for certain clinical manifestations of ATL and of depression of either ICAM-1 or LFA-1 during progression of ATL are discussed.

Animals↗
PubMed1992

Rapid, sensitive, specific, and quantitative detection of human T-cell leukemia virus type 1 sequence in peripheral blood mononuclear cells by an improved polymerase chain reaction method with nested primers.

Improving on the nested double polymerase chain reaction (PCR) described previously, we have developed a new two-step PCR (TS-PCR) method for detecting more specifically the human T-cell leukemia virus type 1 (HTLV-1) proviral sequences in peripheral blood mononuclear cells (PBMC). In our TS-PCR method, the point of modification is to use optimal concentrations of primers in the first amplification step in the range of 0.01-0.025 microM. This increases sensitivity and specificity enough to detect from 1 to 10(5) copies of template DNA without radioisotopes. This method is rapid because of completion in 1 day and is also applicable for quantitative detection of clinical specimens. The data show that the quantitative detection of HTLV-1 proviral sequences by this method correlates with the anti-HTLV-1 antibody titers from serologic analysis of seropositive healthy carriers. Moreover, the TS-PCR method using each specific primer was also attempted for successful detection of other viral genomes; therefore, the principle of this method is widely suitable for routine detection of genomes in the basic and clinical microbiological fields.

Base Sequence↗
PubMed1992

Human T cell leukaemia virus type 1 p21X mRNA: constitutive expression in peripheral blood mononuclear cells of patients with adult T cell leukaemia.

Although the p21X protein of human T cell leukaemia virus type 1 (HTLV-1) is generally thought to be expressed from a doubly spliced mRNA transcript (tax/rex mRNA) that encodes the p40tax, p27rex and p21X proteins, we have shown previously that a novel, alternatively spliced mRNA transcript (p21X mRNA) is responsible for p21X production in HTLV-1-infected cell lines. In the present study, we analysed expression of p21X mRNA and tax/rex mRNA in uncultured and cultured peripheral blood mononuclear cells (PBMCs) from eight patients with adult T cell leukaemia by using a quantitative polymerase chain reaction coupled to reverse transcription. The results demonstrated that the expression of p21X mRNA occurs constitutively in all uncultured and cultured PBMCs, whereas the expression of tax/rex mRNA is inducible in the cultured PBMCs, as described previously. In uncultured and cultured PBMCs from the one specimen in which p21X mRNA was highly expressed, the p21X protein was detectable by Western blotting. On the other hand, p27rex protein was detectable only after cultivation. These findings indicate that p21X mRNA is constitutively expressed in vivo and is responsible for production of p21X protein.

Adult↗
PubMed1991

A novel alternatively spliced viral mRNA transcribed in cells infected with human T cell leukemia virus type 1 is mainly responsible for expressing p21X protein.

The pX sequence of human T cell leukemia virus type 1 (HTLV-1) has been thought to be expressed as a doubly spliced mRNA that codes for p40tax, p27rex and p21X. However, we identified a novel alternatively spliced mRNA in the HTLV-1 infected cells by using reverse transcription followed by the polymerase chain reaction. This mRNA contains only the first and third exons of the doubly spliced mRNA and encodes only p21X. Our data that this mRNA is responsible for expressing p21X exists in most of HTLV-1 infected cells strongly suggests that p21X may play a crucial role for HTLV-1 replication.

Base Sequence↗
PubMed1991

A novel point mutation at codon 146 of the K-ras gene in a human colorectal cancer identified by the polymerase chain reaction.

In this report, point mutations of the K-ras gene at codon 146 were analyzed in 25 cases of colon cancer, 4 cases of lung cancer, and 41 cases of lymphoid malignancy. A codon 146 mutation substituting threonine (ACA) for alanine (GCA) was detected in the tumor tissue of a patient with colon cancer and was not detected in the normal tissue of the same patient. Any additional mutations of the ras gene family were not detected in this patient. These results suggest that the codon 146 mutation of the K-ras gene could be involved in the development of naturally occurring human malignancies.

Antisense Elements (Genetics)↗
PubMed1990

Alteration of N-ras gene mutation after relapse in acute lymphoblastic leukemia.

We investigated N-ras activation in childhood acute lymphoblastic leukemia (dALL) by the polymerase chain reaction (PCR) and the oligonucleotide hybridization method. The frequency of point-mutation of the N-ras gene was not high (2 of 15), and one positive case who relapsed was analyzed in detail. Although N-ras gene activation was detected at both onset and relapse, the mutation sites were different. At onset, Gly (GGT) was changed to Ser (AGT) at codon 12, and at relapse, Gly (GGT) to Asp (GAT) was observed at the same codon. In addition, the DNA at relapse showed a remarkably higher transforming activity than the DNA at onset on two independent recipient cell lines. The identical cell surface phenotype and the same rearrangement patterns of both the immunoglobulin (Ig) heavy chain and T-cell receptor (TCR) gamma chain genes indicated that the leukemic cells at onset and those at relapse were derived from the same precursor cell. Therefore, this case supports the concept that ras activation is not the event initiating leukemogenesis, but may be involved in leukemic progression.

Base Sequence↗
PubMed1989

Identification of a site that mediates transcriptional response of the human beta-actin gene to serum factors.

In quiescent fibroblasts, low-level transcription of the beta-actin gene occurs, and it is rapidly induced by growth factors in serum. Deletion analysis of the 5' upstream region of the human beta-actin gene using a CAT assay showed that the region between +765 and +783 downstream from the cap site, which had enhancer activity in growing NIH3T3 cells, also acted as a serum-response element in quiescent cells. The data suggest that the 19-bp element acts positively as a serum response element. This sequence contains a CC(A/T)6GG sequence which is found in the promoter region of many cytoskeletal and muscle-specific actin genes.

Actins↗
PubMed1989

DNA bending and binding factors of the human beta-actin promoter.

Transcription of the beta-actin gene is rapidly inducible in response to serum stimulation. To determine the regions responsible for serum inducible and basal level expression, the human beta-actin promoter was subjected to mutational analysis. Two distinct elements, the CCAAT homology and the beta-actin specific conserved sequences, were found by a chloramphenicol acetyltransferase expression assay and sequence comparisons, and then analyzed for possible functions. Using a DNA bend assay, it was shown that the conserved sequences included the core of a sequence-directed bend of DNA. Gel mobility shift and DNase I protection assays revealed that the conserved sequences and the CCAAT homology were recognized by binding factors in HeLa cell extracts.

Actins↗
PubMed1989

Analysis of cell variants showing differential susceptibilities to radiation- or chemical-induced neoplastic transformation: differences in their responses to growth factors.

The induction of DNA synthesis in quiescent, density-arrested Balb/c 3T3 cells is known to be controlled by the sequential action of at least two functionally distinct sets of growth factors, so-called "competence factors" and "progression factors." Here we examined this induction pathway in Balb/c 3T3 A31-I variants, which showed differential susceptibilities to radiation- and chemical-induced neoplastic transformation despite their similar susceptibilities to radiation- or chemical-induced cell killing and mutagenesis. DNA synthesis was acquired only with the exposure to progression factors in a highly susceptible cell variant (A31-1-13) whereas both competence factors and progression factors were required for a less susceptible cell variant (A31-I-1). The competent state constitutively produced by an autologous mechanism in the highly transformation-susceptible A31-I-13 cells suggests the existence of an endogenous promoter that acts for the expression of the transformed phenotype in an autocrine fashion when the cells have been initiated by radiation or chemical carcinogens. The growth factor requirements acting as a determining factor for susceptibilities to transformation are discussed.

Animals↗
PubMed1988

An improved method of electroporation for introducing biologically active foreign genes into cultured mammalian cells.

We have developed a modified, reproducible, and efficient method for introducing cloned genes into mammalian cells by using an electric field followed by treatment with sodium butyrate. Transfection frequencies with plasmid pSV2-neo, consisting of an antibiotic (G418) resistance gene and simian virus 40 (SV40) early promoter, by electroporation were higher than those by calcium phosphate DNA precipitation. Treatment with sodium butyrate following electroporation significantly increased the frequency of transfection in various types of cell lines and primary cultured cells including human skin fibroblasts. Treatment with sodium butyrate also increased the transient expression of the gene for chloramphenicol acetyltransferase (acetyl-CoA; chloramphenicol O3-acetyltransferase, CAT, EC 2.3.1.28) when the gene was introduced into BALB/c 3T3 cells by electroporation. Electroporation combined with sodium butyrate treatment is an improved method for stable and transient biochemical transformation of foreign genes in cultured mammalian cells.

Animals↗
PubMed1984

A pathological study in cynomolgus monkeys infected with Edesonfilaria malayensis.

The host response to natural infection with Edesonfilaria malayensis in six female adult cynomolgus monkeys (Macaca fascicularis) imported from Indonesia was examined retrospectively by histopathology and clinical investigations. Reduced values of hemoglobin and hematocrit, an increased number of eosinophils, an elevated level of total protein and a decrease in A/G ratio were noted in hematological and blood chemical examinations of the infected animals. The filarial worms inhabited subserosal connective tissues of the abdominal and the thoracic cavities but not the lumina of the body cavities. There was thickening of the connective tissues, hemorrhage and adhesion of the serosa in the site occupied by the worms and the cysts. Histopathologically, proliferation of the connective tissues and/or granulation tissues, infiltration of eosinophils, lymphocytes and other cells associated with inflammation and hemorrhage were observed. The worms occasionally caused mechanical damage in nearby tissues such as the pancreas and the iliopsoas muscle. In addition, splenic nodules were found in five of the six infected monkeys as a secondary lesion specifically related to the infection with Edesonfilaria malayensis.

Animals↗