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S Nagayoshi

Publications and source records attributed to S Nagayoshi.

16 recordsLinked to original sources
PubMed1990

Characterization of cell fusion in XC cells induced by Suncus murinus mammary tumor virus.

Syncytium formation in a rat tumor cell line (XC) induced by Suncus murinus mammary tumor virus (Sm-MTV) was studied. Multinucleate giant cells containing 20-30 nuclei were formed in a monolayer of XC cells by cocultivation with X-ray-irradiated Sm-MTV producing cells (Sm-MT-1). By fluorescent antibody staining. Sm-MTV antigens were demonstrated in the cytoplasm of syncytia, and budding particles and intracytoplasmic A particles were found in syncytial giant cells by electron microscopy. Cell-free supernatant of Sm-MT-1 was capable of inducing syncytia at a much lower incidence than cocultivation of Sm-MT-1 cells. Syncytium formation was completely inhibited when anti-Sm-MTV bovine serum was added to the coculture medium. Pretreatment of XC cells with actinomycin-D caused a partial reduction of Sm-MTV-induced cell fusion, but syncytium formation did occur at a reduced rate even when cellular RNA synthesis was completely inhibited. Dexamethasone increased virus production in Sm-MT-1 cells, resulting in the enhancement of Sm-MTV mediated syncytium formation. Sm-MTV was found to have a unique characteristic of cell fusion activity on XC cells with striking enhancement by dexamethasone.

Animals↗
PubMed1988

Major structural polypeptides of retrovirus produced by a Suncus murinus mammary tumor cell line and type D retrovirus share interspecies antigenic determinants.

Constitutive polypeptides of retrovirus produced by a Suncus murinus mammary tumor cell line (Sm-MTV) were characterized by immunofluorescence and immunoblotting. The major structural polypeptide of Sm-MTV, molecular weight 44/43K, immunologically cross reacted with the structural polypeptides of Mason-Pfizer monkey virus (MPMV) (molecular weights 27K and 12/10K). Sm-MTV constitutive polypeptides did not show antigenic relatedness with those of the following mammalian retroviruses: murine mammary tumor virus, Rausher murine leukemia virus, Molony murine leukemia virus, Osborn-Mendel rat leukemia virus, feline leukemia virus, RD114 virus, simian sarcoma virus 1, and human T-cell leukemia virus type I. Among the Sm-MTV structural polypeptides, those with molecular weights of 72/69K and 47K were glycosylated.

Animals↗
PubMed1987

Genetic resistance to mammary tumorigenesis in a mouse strain with high murine mammary tumor virus expression.

Although II-TES mice release large amounts of murine mammary tumor virus (MMTV) in milk, they are resistant to mammary tumorigenesis. High mammary tumor incidence was observed in (BALB/ca X II-TES)F1 and (C57BL/6N X II-TES)F1, whereas no mammary tumors developed in BALB/ca X OZ-F)F1. Mammary tumors developed in 68% of (OZ-F X (OZ-F X II-TES)F1 and 45% of (II-TES X (OZ-F X II-TES)F1). These results suggest that the II-TES mouse carries a recessive gene for mammary tumor resistance which does not inhibit MMTV release, and two independent dominant mammary tumor promoting genes which are inhibited by the resistant gene.

Animals↗
PubMed1986

Biochemical and immunological characterization of Suncus murinus mammary tumor virus DNA polymerase.

Enzymological properties of the RNA-directed DNA polymerase associated with the Suncus murinus mammary tumor virus (Sm-MTV) was investigated and its antigenic relatedness to other retroviral DNA polymerases was examined. The enzyme exhibited higher activity in the presence of Mg2+ than in the presence of Mn2+ with endogenous RNA as well as with almost all of the synthetic template X primers tested. Mg2+ was also effective with poly(2'-O-methylcytidylate) X oligodeoxyguanylate which was known to be specific for Mn2+. To examine the immunological relatedness of this enzyme with other retroviral DNA polymerases, remaining Sm-MTV DNA polymerase activity was measured after treatment of this enzyme with various antisera prepared against each of the reverse transcriptases of Mason-Pfizer monkey virus (MPMV), murine mammary tumor virus (MuMTV), simian sarcoma virus-simian sarcoma associated virus (SSV/SSAV), and Rauscher murine leukemia virus (RLV). No inhibition of the Sm-MTV enzyme activity was observed when treated with the latter three antisera with which the DNA polymerase activities of the corresponding retroviruses were fully inhibited. Only the antiserum against MPMV-enzyme, however, was found to slightly inhibit the Sm-MTV enzyme activity. These results indicate that Sm-MTV DNA polymerase has similar enzymological properties to those of MPMV and MuMTV and shares some common antigenic determinant group(s) with MPMV DNA polymerase.

Animals↗
PubMed1986

Class distribution of immunoglobulin-containing plasma cells in the stroma of medullary carcinoma of breast.

A class distribution of plasma cells associated with the stroma in twenty-eight cases of medullary carcinoma of the breast was investigated by an unlabeled immunoperoxidase method. The stroma of the medullary carcinomas tested was found to contain predominantly IgG plasma cells except in two cases. Stroma of the other types of breast carcinoma, including ten cases of papillo-tubular carcinoma, five cases of scirrhous carcinoma, and six cases of medullary tubular carcinoma, contained predominantly IgG plasma cells, although few plasma cells were associated with carcinoma tissues in the latter group. Plasma cells associated with control specimens, including normal breast, fibroadenoma, cystic disease, and intraductal papilloma, were found to be predominantly of IgA type. Few carcinomatous epithelial cells contained secretory components in the cytoplasm, while a number of cells positive for secretory components were observed in acinar and ductular epithelia of normal breast tissues and in benign proliferative lesions of the breast. It is suggested that the lymphoid cells infiltrating the stroma of medullary carcinoma represent a sign of host immune response against the carcinoma cells which is related to the well-known favorable prognosis associated with this tumor.

Adenocarcinoma↗
PubMed1986

Ultrastructural characterization of the retrovirus particles (Sm-MTV) liberated from the mammary tumor cell line (Sm-MT) of a house musk shrew, Suncus murinus (Insectivora).

Detailed ultrastructure of a new type of retrovirus (Sm-MTV) released by cultured cells (Sm-MT) of a spontaneous mammary tumor from a house musk shrew Suncus murinus, Insectivora, is described. The virus particles were revealed as three forms: intracellular; budding; and extracellular. The intracellular type A particles were similar in profile to those associated with mouse mammary tumor cells and tended to form a small cluster of several particles in the cytoplasm. In addition, horseshoe-shaped particles as well as smaller particles in clusters, with doughnut-shaped morphology similar in structure to type A particles, were identified near the clusters of type A particles, although in smaller numbers. The budding particles contained a doughnut-shaped nucleoid, although the nucleoids decreased in size as compared with intracytoplasmic type A particles. The extracellular virions consisted of an envelope and a centrally located nucleoid. In routinely fixed specimens, the former was covered with irregularly distributed fuzzy materials in its surface, and the latter was further composed of a small electron dense core surrounded by an intermediate layer. Tannic acid treatment of cells resulted in the visualization of surface projections on the envelope of virions. Similar projections were also detected exclusively on the plasma membrane where virus budding took place, and not on the normal plasma membrane. The presence of surface projections on the viral envelope was further confirmed by the whole-cell-mounting technique. Together with our previous results of biochemical and immunological investigations, we concluded that Sm-MTV seemed to have closer phylogenetic relatedness with type D viruses of primates than with murine mammary tumor virus.

Animals↗
PubMed1986

High murine mammary tumor virus expression in milk in a low mammary tumor mouse strain and high incidence of mammary tumor in hybrids produced by crossing with another low mammary tumor mouse strain.

Large amounts of murine mammary tumor virus (MMTV) were expressed in milk from a low mammary tumor mouse strain called II-TES, established by crossbreeding DBA/2 mouse strain with two strains of Japanese pet mouse origin. The reciprocal hybrids of the II-TES strain and OZ-F strain, another low mammary tumor strain of Japanese pet mouse origin, developed early-appearing mammary tumors at a high rate, and large quantities of MMTV were expressed in the milk. These findings suggest that different regulatory genes control MMTV expression and mammary tumorigenesis.

Animals↗
PubMed1979

Immunological cross reaction between sera from patients with breast cancer and mouse mammary tumor virus.

Sera of Japanese women with breast cancer and without disorders of the mammary gland gave positive immunofluorescence reaction with mouse mammary tumor cells (MMT cells) producing type-A and type-B virus particles. Among these, 55.1% (49/89) of the sera from patients with breast cancer reacted with MMT cells, whereas 60% (3/5) of the sera from patients with benign mammary hyperplasia (2 of 3 mastopathies, 1 of 2 cystosarcoma phyllodes), 30% (12/40) of the patients with other than breast cancer (4 of 14 stomach cancers, 6 of 20 uterine cancers, 1 of 3 lung cancers, 1 of 3 rectum cancers), and 26.5% (18/68) of the sera from apparently healthy women showed positive reaction with MMT cells. Distribution pattern of the specific fluorescence obtained with positive human sera was similar to that resulting from the reaction with rabbit antiserum of type-A particles. Results of absorption studies and blocking tests also suggested that the reaction was due to the antigenic components common to type-A and -B particles. Furthermore, the results of membrane immunofluorescence tests suggested that some human sera also react with envelope antigen(s) of B particles. Antinuclear antibody was found in sera from 15.7% (14/89) of breast cancer patients by the indirect immunofluorescence tests, and antibody cross-reacting with mouse mammary tumor virus was not found in most of the sera from breast cancer patients who have antinuclear antibody.

Adenocarcinoma↗
PubMed1978

Acute infantile gastroenteritis caused by rotavirus in Japan.

We had an outbreak of acute infantile gastroenteritis accompanied by milky-white stool (called Hakuri in Japanese) during the winters of 1976 and 1977. Stool specimens collected from 72 cases of Hakuri were studied by negative-staining electron microscopy. Rotavirus was detected with a very high frequency (89%). Rotavirus obtained from one of the patients was isolated and passaged in cultures of primary human embryonic kidney cells. Viral antigens could be detected in the cytoplasm of the cells by indirect immuno-fluorescence. The fluorescence-positive cells increased in number with repeated passage. Serum anti-viral activities in 11 patients were titrated by indirect immuno-fluorescence, using the cells infected with the passaged rotavirus. All 11 patients developed IgM responses in the convalescent phase. However, in 4 of the 11 patients, no IgG responses were detected even 2--3 weeks after the onset of illness. The reinfection which has occasionally be seen in our country may be related to these poor IgG responses.

Acute Disease↗
PubMed1976

Studies on live attenuated mumps vaccine. II. Follow-up study on the efficacy of Biken Vaccine.

Clinical and serological follow-ups were made on 18 children for 3 years and on another 18 children for 4 years, after immunization against mumps by attenuated mumps vaccine; Biken vaccine. To evaluate the protective efficacy of the vaccine, matched controls were studied during the same period. Serological examinations revealed that 77% of the vaccinees and 93% of the controls were infected with mumps after close contacts with mumps patients. Regular mumps was contracted by 88% of the controls, but none of the vaccinees. There was no substantial decrease in the antibody titers in unexposed vaccinees after vaccination.

Antibodies, Viral↗