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Biomedical subjects

Y Kikuchi

Publications and source records attributed to Y Kikuchi.

At least 937 records · Page 52Linked to original sources
PubMed1977

An efficient synthesis of polyguanylic acid by a thermophilic polynucleotide phosphorylase.

Polyguanylic acid (poly(G)) was synthesized from GDP in a yield of 60-75% by Thermus thermophilus polynucleotide phosphorylase (polyribonucleotide: orthophosphate nucleotidyltransferase, EC 2.7.7.8) at 70 degrees C, pH 8.5 in the presence of Mg2+. The yield was dependent on the ratio of GDP to Mg2+, but was independent of the concentrations of enzyme or substrate. The maximal rate of GDP polymerization was obtained when the ratio of GDP to Mg2+ was 3:1. However, by prolonged incubation, the higher initial ratio of over 4:1 was preferred because of the rapid consumption of GDP in the reaction mixture. Poly(G) prepared by 1 h incubation was heterogeneous in size from 5 S to over 23 S, but by prolonged incubation of 19 h the size of product converged to 9 S as judged by sucrose density gradient centrifugation. Its chain length was determined by terminal nucleoside analysis to be 200 nucleotides long.

Bacteria↗
PubMed1977

Chromosome aberrations and dominant lethality of mouse embryos after paternal treatment with triethylenemelamine.

Adult male mice were injected intraperitoneally with triethylenemelamine (TEM) at 0.3 mg/kg. These males were mated with untreated females twice a week during 24 days after the treatment. On day 3 of gestation, embryos were flushed out from uteri and examined cytologically as well as cytogenetically. A dominant-lethal test was conducted using the male treated in the same way. Paternal treatment of TEM caused developmental retardation of the embryos obtained from the matings on 20 post-injection days. These embryos frequently showed micronuclei in interphase cells and structural chromosome aberrations in methaphases. Most of these aberrations were chromosome types, such as breaks and exchanges, and premature chromosome condensations. The developmental retardation as well as the frequency of chromosome aberrations was most marked in the matings on post-injection day 13. Similarly, the highest dominant-lethal effect was shown in the group mated on post-injection days 11--13. It was concluded that TEM induces chromosome damage in the post-meiotic germ cells and then this damage in turn produces chromosome aberrations in the embryos, resulting in high incidence of dominant lethality.

Animals↗
PubMed1977

A comparative study of the effect of vitamin E-nicotinate and the combination of vitamin E and nicotinic acid on the hydrogen peroxide-induced platelet aggregation.

The inhibitory effect of vitamin E-nicotinate upon the hydrogen peroxide (H2O2)-induced platelet aggregation was found to be greater than that of either vitamin E alone or the combination of vitamin E and nicotinic acid. Nicotinic acid showed no inhibitory effect. It was suggested that the effect of vitamin E-nicotinate was not due to the additive effect of vitamin E and nicotinic acid produced by hydrolysis, but to the unique and distinctive property of vitamin E-nicotinate itself.

Adolescent↗
PubMed1976

Enzymatic synthesis of oligonucleotides of defined sequence. The "single addition" of 2(3)-O-dihydrocinnamoyl-nucleoside 5'-diphosphate to a primer oligonucleotide catalyzed by a thermophilic polynucleotide phosphorylase.

Several oligonucleotides of defined sequence were synthesized using 2'(3')-O-dihydrocinnamoyl-nucleoside 5'-diphosphates (DHC-NDP) as substrates for polynucleotide phosphorylase [EC 2.7.7.8] from Thermus thermophilus. The enzyme catalyzed the transfer of one nucleotidyl residue from each of the 2'(3')-O-dihydrocinnamoyl esters of CDP, UDP, and GDP to the 3'-terminus of the primer triadenosine diphosphate, (Ap)2A. The products were shown to be (Ap)3C, (Ap)3U, and (Ap)3G by enzymatic analysis.

Adenine Nucleotides↗