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Biomedical subjects

K Iwata

Publications and source records attributed to K Iwata.

At least 433 records · Page 24Linked to original sources
PubMed1981

A model of malignant urinary bladder tumor in rabbits.

We attempted to produce a malignant urinary bladder tumor in rabbits by transplanting tumor cells. Each of 51 male mixed-bred rabbits received 0.3 ml V2 carcinoma cell suspension. The transplantation was done after laparotomy via injection into the bladder wall. Within 2 weeks malignant tumors were observed in the bladder. Without any manipulation to the mucosa, all of the tumors were led to exulceration into the bladder lumen. The incidence of malignant tumor reached 96 per cent. Metastases in these animals were seen in the lungs and para-aortic lymph nodes. This malignant tumor model seems especially suitable for the study of new methods of transurethral treatment of bladder cancer.

Animals↗
PubMed1981

[Studies on the mechanism of antifungal action of ciclopiroxolamine/Inhibition of transmembrane transport of amino acid, K+ and phosphate in Candida albicans cells (author's transl)].

6-Cyclohexyl-1-hydroxy-4-methyl-2(1H)-pyridone, 2-aminoethanol salt (ciclopiroxolamine, Cic, Hoe 296, Batrafen) was fungicidal to growing cultures of Candida albicans, although this effect was apparent after a certain period of cell proliferation, depending upon the drug concentration. Glucose-dependent uptake of all the amino acids tested, K+ and phosphate in starved C. albicans cells was significantly but to a considerably varying extent inhibited by the drug at levels around MIC. Accumulation of amino acid in the cellular pool was more profoundly inhibited than over-all amino acid incorporation into proteins. Cic did not affect the permeability barriers of C. albicans protoplasts or lecithin liposomes. It is presumed from these results that Cic-mediated growth inhibition or death of fungal cells is primarily caused by intracellular depletion of some essential substrates and/or ions, and that such effects are brought about through blockage of their uptake from the medium.

Amino Acids↗
PubMed1980

Structural changes in the glutamine-chargeable Escherichia coli transfer RNA-Trp produced by chemical modification with sodium bisulfite.

Glutamine-mischargeable tRNA produced by sodium bisulfite-treated Escherichia coli tRNA-Trp was isolated by dihydroxyboryl-cellulose affinity column chromatography. This tRNA was shown to have dual specificity tryptophan and glutamine, and, when charged with either amino acid, bound to ribosomes in response to the non-sense codon UAG but not in response to the tryptophan codon UGG. The results were consistent with the reported properties of Su+7 tRNA. The bisulfite-treated tRNA-Trp migrated as two bands during polyacrylamide gel electrophoresis. The faster moving band (band I) coincided with that of untreated tRNA-Trp. The slower moving band (band II) coincided with the glutamine-chargeable tRNA-Trp. Su+7 tRNA behaved like band II tRNA upon gel electrophoresis. Nucleotide sequence analysis showed that a cytidine-uridine transition occurred at the 1st or the 2n position of the anitcodon of band II tRNA. Band I and band II tRNAs differed from each other in their thermal melting profiles. It is suggested that the single base change in the anticodon is responsible for the altered conformation of band II tRNA.

Autoradiography↗
PubMed1980

Single-step selection of mouse FM3A cell mutants defective in thymidylate synthetase.

A tritium-suicide method for isolating thymidine auxotrophic mutants is described. Mutagenized mouse FM3A cells were cultured in medium containing [3H] deoxyuridine. Most of the surviving clones examined showed a phenotype of absolute thymidine auxotrophy. This phenotype is very stable and was found to be genetically recessive in cell-cell hybridization experiments. The growth of these variant clones was not supported by various pyrimidine nucleosides other than thymidine. The activity of thymidylate synthetase in crude extracts of these clones was less than 1% of that of FM3A cells. These results strongly indicate that the thymidine auxotrophic phenotype resulted from a genetic defect in thymidylate synthetase.

Animals↗
PubMed1980

Nevoid basal cell epithelioma syndrome in Japan.

A 49-year-old Japanese man with typical features of nevoid basal cell epithelioma syndrome is reported. The patient had cystic lesions of the jaw bone, multiple basal cell epitheliomas of the scalp and face, pits on the palms and soles, bifid ribs, scoliosis and calcification of the falx cerebri. In Japan five certain cases have been reported previously. We added one new case and reviewed the other five cases briefly.

Basal Cell Nevus Syndrome↗
PubMed1980

Detection of antibody-coated bacteria in the bile in experimental cholecystitis.

Detection of antibody-coated bacteria (A C B) in the bile sediment was tried in experimental cholecystitis which were produced in male rabbits by inoculation of mixture of E. coli and 5% sodium desoxycholate. A C B in the bile sediment was demonstrated in all cases by the direct immunofluorescent antibody technique. All cases showed positive cultures and all these isolates were the same strain as inoculated.

Animals↗