Search PubMed⌕ Search

Biomedical subjects

N Otaki

Publications and source records attributed to N Otaki.

At least 37 records · Page 2Linked to original sources
PubMed1985

Cd2+-induced synthesis of metallothionein in HeLa cells.

HeLa cells synthesize metallothioneins in response to Cd2+. The kinetics of thionein (apoprotein of metallothionein) synthesis was studied by pulse-labelling the cells with [35S]cysteine and measuring relative amounts of the labelled thioneins separated by electrophoresis. Thionein synthesis rapidly increases in the first 6-8 h after exposure to 0.5 micrograms of Cd2+/ml, and begins to decrease in a few hours after reaching the maximum. However, the rate of synthesis never returns to the basal value at least in 30 h after Cd2+ exposure; instead, the second increase in thionein synthesis occurs at 16-18 h. A possible regulatory mechanism of thionein synthesis is discussed from these results, together with the data on intracellular accumulation and subcellular distribution of 109Cd2+. The initial increase of thionein synthesis is accompanied by an increase of mRNA coding for thioneins (MT-mRNA). The induction of MT-mRNA is sensitive to Actinomycin D, but not to cycloheximide, suggesting transcriptional regulation without any mediating protein synthesis. Two thionein isomers are coded for by mRNA molecules of almost the same size, which is similar to that of hepatic MT-mRNA of mouse and rat.

Cadmium↗
PubMed1985

Evidence for more than two metallothionein isoforms in primates.

Two isoforms of metallothionein (MT) have in general been identified in mammalian cells. We have analyzed Cd2+-induced MTs of primate origin and demonstrated the presence of more than two isoforms. Four low molecular weight Cd2+-binding proteins were separated from Cd2+-exposed HeLa cells by gel filtration and ion-exchange chromatography and identified as MTs by amino acid analysis. These were carboxymethylated and analyzed by electrophoresis under denaturing conditions. Three of these proteins were found to be distinct molecules. We also analyzed hepatic MTs from Cd2+-exposed rhesus monkeys, which have previously been partially separated. In this case, five distinct isomers were detected.

Animals↗
PubMed1975

Tyrosinase as glycoprotein.

Purified tyrosinase T1 was incubated with neuraminidase. The catalytic activity of tyrosinase was essentially retained, after this treatment. The tyrosinase band (Dopa stained) was transformed into a new less anodic form, similar to tyrosinase T2, on disc electrophoresis. The band of protein was also converted to the same position as the Dopa stained. The other hand, the only one PAS stained band of native tyrosinase T1 was splitted into the three slower-moving bands. One was consistent with Dopa and protein stained bands. The other two were much more slower than the former band and completely free of peptide and enzymic activity. The PAS-densitometric value of native tyrosinase T1 was almost equal to those of three separated bands in total. These results suggest that mammalian tyrosinase is a kind of glycoprotein.

Animals↗
PubMed1975

Bone and kidney lesions in experimental cadmium intoxication.

Young male rats were fed a diet containing cadmium (0, 10, 30, 100, and 300 ppm) so as to morphologically investigate the relationship between bone and kidney lesions caused by experimental cadmium intoxication. In the early stage of the experiment, before the occurrence of kidney lesions, ingeted cadmium caused osteoporotic changes in bone. In later stages, slight pathologic changes in the kdidney occurred in association with urinary excretion of cadmium. However, there was no evidence of osteomalacic change in bone during the 12-week experimental period. These findings suggest that cadmium may act primarily on bone, rather than secondarily through disturbances of the kidneys, which have some protective ability against cadmium intoxication in the early stage of ingestion of the metal.

Animals↗