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Biomedical subjects

M Umeda

Publications and source records attributed to M Umeda.

At least 505 records · Page 28Linked to original sources
PubMed1977

Effect of methylnitrosocyanamide on cultured mammalian cells.

Effect of methylnitrosocyanamide (MNC) on a cultured mammalian cell line was examined in comparison with that of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). It was observed that MNC was about 3 times more potent than MNNG in the experiments on toxicity and inducibility of chromosome aberration and mutation. An increase in toxicity of MNNG was observed by minimizing the elevation of pH, while toxicity of MNC was more potent in the serum-free condition than in the presence of serum. Further, MNC was shown to be extremely rapid-acting, that is, 10 min was enough to exert its toxic effect.

Cell Division↗
PubMed1976

[Microdetermination of TSH in dried blood spot--its use in the mass-screening for congenital or juvenile primary hypothyroidism (author's transl)].

Blood TSH (Thyroid Stimulating Hormone) was successfully measured by radioimmunoassay in a dried blood spot on filter paper which is obtained in newborn screening for metabolic disorders. By this method, the minimal detectable level of blood TSH was about 10 muU/ml, which is the approximate upper limit of normal values of blood TSH. Good correlation was found between the TSH values obtained from this specimen and from liquid serum samples from the same subjects. The duplication of assay of a single sample was not necessary. A screening program using the method described here was initiated and a 4 year old infant was found to have primary hypothyroidism, later verified by other testing methods. Since the technique is simple and adequately sensitive for the detection of hypothyroidism, it could be a valuable method for use in mass-screening of newborns for congenital hypothyroidism.

Child, Preschool↗
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↗
PubMed1975

Difference in sedimentation profiles on DNA from various cell types during lysis periods by direct alkaline sucrose gradient analysis.

Sedimentation condition for DNA from various kinds of cultured mammalian cells lysed directly on the top of an alkaline sucrose gradient was examined after the lysis for various periods at 19 degrees or 37 degrees. When cultured normal embryo cells from human, mouse, and Syrian hamster were analyzed, "complex" and "main" peaks were demonstrated. The former, which had low sedimentation coefficient, was obtained after 1 or 2 hr of lysis at 19 degrees and resolved after a 4-hr lysis into the latter which had a higher sedimentation coefficient. When cultured cells with malignant history were analyzed, a sharp and high peak was observed after 1 or 2 hr of lysis of 19 degrees and this peak resolved into the "main" peak after a 4-hr lysis. When the cells were lysed at 37 degrees, the "main" peak appeared after 1 or 2 hr of lysis. Metaphase cells in which the chromatin is condensed heterchromatically were also analyzed. Sedimentation profiles from normal human embryo cells and HeLa cells in metaphase were similar to those obtained from cells with malignant history in interphase during various lysis periods. From these data the difference in the sedimentation pattern between normal embryo cells and cells with malignant history could be interpreted as a phenotypic expression of the cells.

Animals↗
PubMed1975

Dissociation of lipid and protein from cell-DNA by direct alkaline sucrose gradient analysis.

Hela cells and normal human embryo cells were analyzed in alkaline sucrose gradients after labeling with 14C-thymidine and 3H-choline chloride or 3H-amino acid mixture. Radioactivities from both choline and amino acids were observed in accord with DNA peak when the labeled cells were analyzed after 1 or 2 hour lysis in the lysing solution at 25 degrees C; i.e., a sharp and high peak observed with HeLa cells and a peak with more reduced sedimentation rate observed with normal human embryo cells could be considered to indicate the association of DNA with lipid and protein components, probably the nuclear membrane. The peak which was obtained after 4 hour lysis at 25 degrees C or after 1 hour lysis at 37 degrees C was not associated with label from choline and amino acids and, thus, proved to have been released from lipid and protein fractions. When metaphase HeLa cells were collected after labeling with choline or amino acids and then analyzed, the radioactivity was demonstrated in the sharp and high peak after 1 or 2 hour lysis at 25 degrees C; that is, the lipid and protein portions might be somehow associated with the mammalian metaphase chromosomes.

Cells, Cultured↗
PubMed1975

Mutagenicity of dimethylnitrosamine to mammalian cells as determined by the use of mouse liver microsomes.

The mutagenicity of dimethylnitrosamine (DMN) to mammalian cells was investigated using a metabolic activation system. Mutation from 8-azaguanine (8AG) sensitivity to resistance in FM3A cells, a cell line derived from C3H mouse mammary carcinoma, was found only in the presence of dimethylnitrosamine, mouse liver microsomes and cofactors. The different inducibility of the mutation was shown by the use of liver microsomes from different strains of mouse.

Animals↗
PubMed1975

Mutagenic activity of furylfuramide on cultured mouse cells.

Effects of furylfuramide (FF) on cultured FM3A cells a C3H mouse mammary carcinoma cell line, were examined. FF inhibited the growth at 10(-4.5) M, and provoked enlargement of cellular, nuclear and nucleolar size, cytoplasmic vacuolation and granular aggregation of chromatin. Chromosome preparation demonstrated severe aberrations in nearly 90% of mitotic plates after 24 and 28 hour treatment. The changes included gaps, breaks, exchanges and fragmentations, but were at chromatid level. Time course study of the incorporation of radioactive precursors showed the gradual but remarkable inhibition of 3H-thymidine uptake whereas 3H-uridine and 3H-leucine uptakes were fairly maintained. Thus, it is suggested that FF induced the block of G1 phase and the delay of S and/or G2 phase. According to the results of alkaline sucrose gradient analysis of cell DNA, breakage of the treated cell DNA was induced and the induced breakage was recovered after the incubation without FF. The capacity to induce 8-azaguanine-resistant mutant cells by FF was shown remarkably high.

Animals↗