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Biomedical subjects

M Umeda

Publications and source records attributed to M Umeda.

At least 487 records · Page 27Linked to original sources
PubMed1979

Inducibility of chromosomal aberrations by metal compounds in cultured mammalian cells.

Metal compounds were tested for their ability to induce chromosomal aberrations in cultured mammalian cells. Chromosomal aberrations were induced by the application of some Cr, Mn and Ni compounds. Among 6-valent Cr compounds, K2Cr2O7 and CrO3 induced high levels of aberrations, at rates which were similar for Cr-equivalent doses. The perchromate compounds were more efficient in producing chromosomal aberrations than was a chromate compound, K2CrO4. A 3-valent Cr compound, Cr2(SO4)3, was less toxic and failed to induce a demonstrable increase in chromosomal aberrations. KMnO4 induced aberrations, but at a low rate. As to Ni compounds, NiCl2 and (CH3COO)2Ni induced few aberrations. Administration of K2Ni(CN)4 induced only gaps. NiS induced a low but definite increase in chromosomal aberrations. The rate of these aberrations increased with an increase in treatment time from 24 to 48 h, indicating a time-dependent increase in the hereditable toxicity of metal compounds. CdCl2 and HgCl2 were somewhat toxic, but failed to induce chromosomal aberrations in the present study.

Animals↗
PubMed1979

Inducation of chromosomal aberrations in cultured mammalian cells by nickel compounds.

The effects of 4 Ni compounds, nickel chloride, nickel acetate, potassium cyanonickelate, and nickel sulfide were studied in a line of mammary carcinoma cells from the C3H mouse. All 4 were easily taken up by the cells and reacted with protein, RNA, and possibly DNA. Measurements of leucine, uridine, and thymidine uptake during exposure showed that the syntheses of protein and DNA were more sensitive than RNA. Chromosomal aberrations were observed during the recovery period following the end of the treament with Ni. The implications of these results were discussed with respect to the carcinogenicity of the compounds and to the recommended protocols for mutagenicity testing by chromosomal aberrations.

Animals↗
PubMed1979

The production of chaetoglobosins, sterigmatocystin, O-methylsterigmatocystin, and chaetocin by Chaetomium spp. and related fungi.

Production of mycotoxins by Chaetomium spp. and related fungi on rice culture was examined by a combination of cytotoxicity tests using HeLa cells and thin-layer chromatography. Three species, C. mollipilium, C. rectum, and C. subaffine, as well as C. cochliodes and C. globosum, were proved to produce chaetoglobosins. From cultures of four strains of Chaetomium sp., assigned to C. thielavioideum, and one strain of Farrowia sp., chaetocin, sterigmatocystin, and O-methylsterigmatocystin were isolated. Morphological characteristics of the producers of sterigmatocystins are described.

Ascomycota↗
PubMed1979

Mutagenicity of quercetin and kaempferol on cultured mammalian cells.

Mutagenic activity of quercetin and kaempferol on V79 Chinese hamster cells was investigated. Quercetin was proved to have mutagenicity not only by metabolic activation system using rat liver microsomes, but also by direct application method. Kaempferol was mutagenic by metabolic activation system, but its activity by direct method seemed very low. These data suggest that the tested flavonoids seem to be metabolized for exerting their mutagenic activity and V79 cells themselves have an enzymic activation system which metabolizes at a very slow rate but in a cumulative way.

Animals↗
PubMed1979

Effect of hyperthermia on DNA single-strand breaks induced by bleomycin in Hela cells.

The effect of hyperthermia (43 approximately 45 degrees) on DNA single-strand breaks induced by bleomycin was examined in HeLa cells by the alkaline sucrose gradient sedimentation analysis. When HeLa cells were exposed to a temperature of 43 degrees approximately 45 degrees for 1 hr, only a small number of DNA single-strand breaks than bleomycin treatment at 37 degrees. The DNA strand breaks induced by bleomycin were almost completely repaired by post-treatment incubation of the cells in the control medium at 37 degrees. On the contrary, the repairing capacity of the cells was markedly inhibited by post-treatment incubation at 43 degrees, and this inhibition of cell repair seemed irreversible because no repair was found after an additional incubation of the cells at 37 degrees for 1 hr. These results support the possibility that the mechanism of synergism between the effect of bleomycin and hyperthermia may be related to the inhibition of DNA repair.

Bleomycin↗
PubMed1977

Establishment and characteristics of three mouse cell lines from embryos of different inbred strains.

Three cell lines were established from embryos of DDD, AKR, and C3H mouse strains based on "3T3" transfer schedule. These cell lines were designated as Y-DD, Y-AK, and Y-CH, Y-DD and Y-CH showed a gradually increasing growth rate during the course of their establishment, whereas Y-ak indicated a constant growth rate, a low level of saturation density, and a tetraploid range of chromosome mode. In transformation experiment, control cultures of Y-DD and Y-CH already lost a density-dependent inhibition, but Y-AK was found to be very sensitive to density-dependent inhibition. Y-AK showed a higher activity in benzo[a]pyrene metabolism (4100 pmol/10(6) cells/24 hr) than Y-DD and Y-CH (700 and 2600 pmol/10(6) cells/24 hr).

4-Nitroquinoline-1-oxide↗
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↗
PubMed1977

Benzo[a]pyrene metabolizing activity of cultured cells as determined by a simplified radiometric method.

Benzo[a]pyrene metabolism in various kinds of mammalian cultured cells was measured by a simplified method. Cells growing in the bottom of glass test tubes were treated with 2micron of 14C-benzo[a]pyrene for 24 hr; unmetabolized benzo[a]pyrene was then extracted with organic solvents in the same test tube, and the amount of water-soluble products recovered in the aqueous phase was measured by a liquid scintillation counter. Among rodent embryo cells, embryo cells of C3H/He mice and Syrian hamsters showed a higher activity in benzo[a]pyrene metabolism than those of DDD, AKR, and C57BL/6 mice. Several cell line sensitive to density-dependent inhibition, such as Y-AK, DL1, and C3H/10T1/2, actively metabolized benzo[a]pyrene to water-soluble products. The metabolizing activity of C3H/He mouse embryo cells was markedly enhanced by pretreatment with benz[a]anthracene. tthe amount of water-soluble products by phytohemagglutinin-stimulated human lymphocytes was much less than that by most cultured cell lines and embryo cells, but clearly increased with extension of culture days.

Animals↗