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Biomedical subjects

T Nishimoto

Publications and source records attributed to T Nishimoto.

At least 217 records · Page 12Linked to original sources
PubMed1983

Recovery of a hybrid vector, derived from bovine papilloma virus DNA, pBR322 and the HSV tk gene, by bacterial transformation with extrachromosomal DNA from transfected rodent cells.

A bovine papilloma virus (BPV)-pBR322-derived recombinant plasmid carrying a 2-kb fragment of Herpes simplex virus DNA containing the thymidine kinase (tk) gene is capable of transforming tk- cells of mouse L and Syrian hamster BHK21 lines to tk+. In transformed cells a small proportion of the plasmid DNA is present as extrachromosomal elements while the remainder appears to be integrated into the genome. It was possible to recover plasmids indistinguishable from the input DNA by transformation of Escherichia coli bacteria with low-molecular-weight DNA isolated from the transformed mouse and hamster cells and consisting of BPV-pBR322-HSV tk+ plasmids.

Animals↗
PubMed1983

Directional difference of urethral pressure profile in anterior, posterior and lateral components of canine urethra.

The urethral pressure profile (UPP) was recorded in anterior, posterior, and right and left lateral portions of the canine urethra using a newly designed catheter with only one eye around the circumference of the tip for UPP recording. Our single-eye catheter made it possible to measure UPP in the four aspects separately and confirmed that there was a directional difference in UPP.

Animals↗
PubMed1982

Large-scale selection and analysis of temperature-sensitive mutants for cell reproduction from BHK cells.

Temperature-sensitive (ts) mutant cells for cell reproduction were isolated from the Syrian hamster cell line BHK21/13 by multiple culturing in the presence of 5-fluoro-2'-deoxyuridine (FdU) at 37.5 degrees after N-methyl-N'-nitro-N-nitrosoguanidine mutagenesis. A simple method for cell fusion was devised, which enabled us to perform complementation studies with a large number of ts mutants. By using the method we have analyzed 219 ts mutants and classified them into 18 complementation groups. Mutants that belonged to the same complementation groups tended to exhibit similar patterns of inhibition of DNA synthesis at 39.5 degrees; however, some mutants belonging to the same group showed somewhat different patterns, probably due to occurrence of different mutations in the same gene. Distribution of the ts mutants among the 18 complementation groups was uneven; more than 50% of the mutants examined were assigned to complementation group B and G. The mutations belonging to complementation group B and G were found to be linked to the X chromosome.

Animals↗
PubMed1982

Nature and distribution of mucosubstances in human mature enamel identified by enzyme electron microscopy.

Longitudinal slices of 12 freshly extracted human third molars fixed in 10 per cent neutral formalin were demineralized with 1M lactic acid. Ultrathin sections of slices were stained with ruthenium red or silver methenamine. The reaction products were mainly found in the prism sheath regions. To identify the mucosubstances, the digestion tests with chondroitinase ABC, AC, hyaluronidase and neuraminidase were performed. It was concluded that the major component of the organic matrix of inner human dental enamel is chondroitin 4-sulphate or chondroitin 6-sulphate localized in prism sheath regions and inter-crystalline spaces.

Chondroitin Sulfates↗
PubMed1982

Sperm penetration in vitro of human oocytes matured in a chemically defined medium.

Human oocytes were obtained randomly from the ovaries excised from 28 patients at different stages of the menstrual cycle. When 114 oocytes were cultured for 40-40.5 h in a chemically defined medium 80 showed degeneration. When 16 of the remaining 64 oocytes were examined for their maturation, germinal vesicle breakdown (GVBD) had occurred in 11 oocytes. Another 48 oocytes were inseminated by ejaculated spermatozoa which were washed twice and preincubated for 3 h. When examined 10 h later, 19 (39.6%) were penetrated with an enlarged sperm head or male pronucleus(ei) and its corresponding sperm tail(s).

Adult↗
PubMed1981

Inhibition of DNA synthesis and cell cycle in Chinese hamster cells by sterol-binding polyene amphotericin B.

Amphotericin B, a sterol-binding polyene antibiotic, was found to inhibit DNA synthesis more than protein or RNA synthesis of asynchronous cultures of Chinese hamster V79 cells. DNA synthesis in the asynchronous V79 cells was inhibited to 40--60% of the control activity in the presence of 50 micrograms/ml amphotericin B. However, addition of 50 micrograms/ml of polyene immediately after to onset of DNA synthesis (early S phase) caused a drastic reduction of DNA synthesis (below 10--20% of the control in synchronized V79 cells, whereas the inhibition was much lessened when the polyene was added 1 h later (middle S phase). In contrast, there was no inhibition of DNA synthesis by amphotericin B in an amphotericin-B-resistant (AMBR) clone that was derived from V79. Flow microfluorometry analysis confirmed that a large number of asynchronous V79 cells were arrested in the G1 phase of the cell cycle when treated with lower dose of amphotericin B. A higher dose of the polyene antibiotic also accumulated cells at the G2 (or at both S and G2) phase as well as the G1 phase. Morphological studies by scanning electron microscope showed an increased number of V79 cells with decreased microvilli in V79 cells treated with amphotericin B.

Amphotericin B↗
PubMed1981

The synthesis of protein(s) for chromosome condensation may be regulated by a post-transcriptional mechanism.

A temperature sensitive mutant of BHK21, tsBN2, showed a premature chromosome condensation (PCC) upon the temperature shift of 40.5 degrees, even in the absence of DNA replication. The induction of PCC requires new protein synthesis, but not necessarily new RNA synthesis. Our data suggested that the messenger RNA for chromosome condensation starts to be transcribed at the beginning of S phase. At the permissive temperature (33.5 degrees), the messenger RNA for chromosome condensation translated with a very slow rate during S phase and rapidly in G2-M phase. At the nonpermissive temperature (40.5 degrees), however, those messenger RNAs were translated anytime, so that various figures of PCC appeared depending on the cell cycle. On the way of PCC induction, ribosomal RNA synthesis was inhibited at first, as expected from mitosis. Our data suggested that the synthesis of protein(s) for chromosome condensation was regulated by the post-transcriptional mechanism, in which tsBN2 might be defective, especially at the translational level.

Animals↗