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Biomedical subjects

T Tsutsui

Publications and source records attributed to T Tsutsui.

At least 361 records · Page 20Linked to original sources
PubMed1978

Neoplastic transformation induced by a direct perturbation of DNA.

Treatment of Syrian hamster embryo cells with 5-bromodeoxyuridine followed by near ultraviolet irradiation results in neoplastic transformation of these cells. This demonstrates that a direct perturbation of DNA is sufficient to initiate neoplastic transformation.

Bromodeoxyuridine↗
PubMed1978

Induction of 6-thioguanine- and ouabain-resistant mutations in synchronized Syrian hamster cell cultures during different periods of the S phase.

Cells of a transformed Syrian hamster line, BP6T, were synchronized by a period of growth in low serum with a subsequent blockage of the cells at the G1/S boundary by hydroxyurea. This method provided cells with nearly 100% synchrony, although approximately 20% of the cells were non-cycling. The cells were then treated with 10(-5) M 5-bromodeoxyuridine for 1 of 5 1-h periods during the S phase and subsequently irradiated with near-ultraviolet light for 5 min. The BrdU plus irradiation treatment induced 6-thioguanine- and ouabain-resistant mutants while BrdU alone or irradiation alone was not mutagenic. 6-Thioguanine-resistant mutants were induced only during early S phase by BrdU plus irradiation treatment. Ouabain-resistant mutants, however, were induced in a biphasic pattern, during early S phase and also during late S phase. The induction of ouabain-resistant mutants at two distinct periods of S phase suggests the presence of two loci for the gene(s) of Na+/K+ ATPase.

Cell Cycle↗
PubMed1977

Comparison of mutagenicity and inducibility of DNA single-strand breaks and chromosome aberrations in cultured mouse cells by potent mutagens.

Induction of 8-azaguanine-resistant mutation, DNA single-strand breaks, and chromosome aberrations by treatment with ethyl methanesulfonate (EMS), N-methyl-N'nitro-N-nitrosoguanidine (MNNG), nitrogen mustard hydrochloride (HN2), or 4-nitroquinoline 1-oxide (4-NQO) was compared under similar experimental conditions using cultured FM3A cells from a C3H mouse mammary carcinoma. All the chemicals induced 8-azaguanine-resistant mutations and chromosome aberrations in a dose-dependent manner; a good correlation between the two activities was demonstrated. An alkaline sucrose gradient method demonstrated that DNA single-strand breaks were induced only in a high dose range by 1- and 24-hr treatment with the chemicals. One exception was that a 1-hr treatment with HN2 produced an anomalous sedimentation pattern. These data suggest that caution is necessary for the interpretation of results obtained by the alkaline sucrose gradient analysis, and that examination of mutagenicity and chromosome aberrations is more feasible as screening procedures for potential mutagens than analysis of DNA single-strand breaks.

4-Nitroquinoline-1-oxide↗
PubMed1977

Mutagenicity and inducibility of DNA single-strand breaks and chromosome aberrations by various mycotoxins.

Mutagenicity of various mycotoxins and the efficiency of mutagenic mycotoxins in producing DNA single-strand breaks and chromosome aberrations were examined using a mammalian cell line. It was found that aflatoxin-B1, mycophenolic acid, patulin, penicillic acid, and sterigmatocystin induced 8-azaguanine-resistant mutations. Aflatoxin-B1, mycophenolic acid, and sterigmatocystin had little effect on DNA single-strand at high concentrations. In the treatment with patulin and penicillic acid, severe breaks were found at higher concentration than at the concentration where the mutation was induced. Incidence of chromosome aberrations by the treatment with these mycotoxins correlated fairly well with their mutagenic activity. Chaetoglobosin-B, fusarenon-X, (--)luteoskyrin, and ochratoxin-A did not induce 8-azaguanine-resistant mutation.

Aflatoxins↗
PubMed1976

Mutagenic effect of sodium nitrite on cultured mouse cells.

Effect of sodium nitrite on cultured FM3A cells, a C3H mouse mammary carcinoma cell line, was examined. The chromosomal preparations demonstrated that severe aberrations were induced in more than 80% of the mitotic plates at 10(-2) M and in nearly 40% at 10(-25) M after 24 and 48 h treatment. According to the results of alkaline sucrose gradient analysis sedimentation profiles of cell DNA treated at as high as 10(-1) M for 24 h scarcely changed from that of control cell DNA. Induction of 8-azaguanine-resistant mutation was demonstrated above 10(-3) M sodium nitrite.

Animals↗
PubMed1976

Effect of tetracycline on cultured mouse cells.

By use of an assay system in vitro with cultured FM3A cells from a C3H mouse mammary carcinoma, tetracycline hydrochloride was found to have the ability to induce an 8-azaguanine-resistant mutation. It is suggested that an assay system using mammalian cells for the detection of mutagenicity of certain substances having antimicrobial action is more practical than a system using bacteria. As other effects of tetracycline hydrochloride on FM3A cells, the damage on chromosomes and the inhibition of syntheses of protein and nucleic acids were demonstrated.

Azaguanine↗