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Biomedical subjects

J Okuda

Publications and source records attributed to J Okuda.

At least 181 records · Page 10Linked to original sources
PubMed1980

Phospholipase A in the plasma membranes in ascites hepatomas and of normal livers in rat.

Phospholipase A activities in plasma membranes (PMs), isolated from rat ascites hepatoma cells (AH 130, AH 130FN, AH 7974, and AH 7974F), were determined and compared with those in PMs isolated from normal rat livers (neonatal, resting adult, and regenerating adult livers). All the PMs had a hydrolyzing action on 1-acyl-2[14C]oleyl-sn-glycero-3-phosphoethanolamine but not on similarly labeled phosphatidylcholine. After hydrolysis, the radioactivity was recovered in both the lyso derivative and the free fatty acid produced. Thus, the presence of phospholipases A1 and A2 in the PMs, with an optimal pH around pH 9, was demonstrated. In all the hepatoma PMs, te phospholipase A2 activity was greatly reduced or almost lacking, whereas in the PMs from normal resting and growing livers strong phospholipase A2 activity was detected equally but with a specific activity higher than that of phospholipase A1. Triton X-100 treatment had an activating effect on phospholipase A1 but an inhibitory effect on phospholipase A2 of the resting liver PMs, while the same treatment was inhibitory for both the phospholipase A1 and A2, activities of the hepatoma PMs.

Aging↗
PubMed1980

Comparative study of the phospholipid composition of plasma membranes isolated from rat primary hepatomas induced by 3'-methyl-4-dimethylaminoazobenzene and from normal growing rat livers.

Plasma membranes (PM's) were isolated from primary hepatomas induced in Wistar rats by 3'-methyl-4-dimethylaminoazobenzene, from nonhepatomal regions of the same rat livers, and also from various normal rat livers, including the resting and regenerating livers of adult rats and developing livers of postnatal rats. Phospholipid analyses of these PM preparations revealed the following differences in the hepatoma PM in comparison with those of the PM of normal adult resting livers: (a) decrease in the content of total phospholipids; (b) large increase in plasmalogen content; (c) relative increase of sphingomyelin and ethanolamine phospholipids, and the decrease of choline phosphoglycerides, i.e., decrease of the ratios of choline phosphoglycerides to choline phosphosphingoside and of choline-containing phospholipids to ethanolamine-containing phospholipids; (d) decrease in phosphatidylserine and phosphatidylinositol. The phospholipid composition of the PM's from normal growing livers showed definite decreases in phosphatidylserine and sphingomyelin and increases in ethanolamine phospholipids; however, no significant alteration was observed in plasmalogen content in comparison to the PM of normal adult resting livers. The PM from the nonhepatomal regions of the hepatoma-bearing livers did not show those differences observed in hepatoma PM.

Animals↗
PubMed1979

The localization of mutarotase in rat kidney.

The localization of mutarotase in rat kidney was investigated by fluorescein-labelled and peroxidase-labelled antibody techniques, and by method of isolation of the nuclei and cytoplasm in non-aqueous solvents. In these immunohistochemical studies, mutarotase was almost exclusively recognized in the nuclei of epithelial cells of renal tubules and glomeruli in rat. The specific activity of mutarotase was found to be 1.5 times higher in the nuclei (122 units/g dry wt) than that in the cytoplasm (80 units/g dry wt) isolated with non-aqueous solvents. These results suggest that mutarotase may be involved in the metabolism of D-glucose in nuclei.

Animals↗
PubMed1979

Different effects of D-glucose anomers for respiration of bacterial germinated spores.

Effects of alpha- or beta-D-glucose on the respiration of germinated spores (only germinated spores not including swollen spores and elongated spores) of Bacillus subtilis and B. megaterium were studied. In our conditions, net amount of oxygen consumed by 10(10) germinated spores of B. subtilis per min after addition of alpha- or beta-D-glucose was 1.6 microgram or 6.6 microgram (beta/alpha = 4.13), while that by B.megaterium was 4.5 microgram of 6.8 microgram (beta/alpha = 1.51), respectively. However, the net amounts of oxygen consumed by 10(10) vegetative cells per min after addition of alpha- or beta-D-glucose were identical, for B.subtillis in both cases 443.0 microgram and for B.megaterium in both cases 604.4 microgram.

Bacillus megaterium↗
PubMed1979

Exchange of free and bound coenzyme of flavin enzymes studied with [14C]FAD.

The exchange of bound FAD for free FAD was studied with D-amino acid oxidase (D-amino acid:oxygen oxidoreductase (deaminating), EC 1.4.3.3) and beta-D-glucose oxidase (beta-D-glucose:oxygen 1-oxidoreductase, EC 1.1.3.4). For a simple measurement of the reaction rate, equimolar amounts of the enzyme and [14C]FAD were mixed. The exchange occurred very rapidly in the holoenzyme of D-amino acid oxidase at 25 degrees C, pH 8.3 (half life of the exchange: 0.8 min), but slowly in the presence of the substrate or a competitive inhibitor, benzoate. It also occurred slowly in the purple complex of D-amino acid oxidase. In the case of beta-D-glucose oxidase, however, the exchange occurred very slowly at 25 degrees C, pH 5.6, regardless of the presence of the substrate or p-chloromercuribenzoate. On the basis of these findings, the turnover of the coenzymes of flavin enzymes in mammals is discussed.

Animals↗
PubMed1979

Anomeric preferences of D-glucose uptake and utilization by cerebral cortex slices of rats.

On aerobic incubation of rat cerebral cortex slices with anomers of D-glucose and with 2-deoxy-D-glucose (2DG) for 5 min, the disappearance of beta-D-glucose from the incubation mixture was greater than that of alpha-D-glucose and both anomers had a greater rate of disappearance than that of 2DG. In addition, there were significantly greater consumption of oxygen and production of lactate with the beta-anomer than with the alpha-anomer. In similar experiments with 3H-labeled D-glucose anomers and [1-3H]-3-O-methyl-D-glucose (3MG), the accumulation of [1-3H]-beta-D-glucose (up to 5 min) by rat cerebral cortex slices was greater than that of [1-3H]-alpha-D-glucose. Although initially lower than that of the anomers, the accumulation of [1-3H]-3MG increased at a greater rate and, by 5 min of incubation, was greater than that of both glucose anomers. This preferential accumulation was seen to disappear when the slices were preincubated with 2DG (hexokinase inhibitor) or when the temperature of incubation was reduced to 20 degrees C. Under those conditions the data with the glucose anomers were similar to those obtained with 3MG. Our data then suggested that the greater accumulation of beta-D-glucose than of alpha-D-glucose by the slices was probably not due to differences in transport through brain cell membranes but rather to the preferential metabolism of the beta-D-glucose.

Animals↗
PubMed1979

Effects of alpha- and beta-D-glucose on germination of spores of Bacillus megaterium QM B1551.

The effects of D-glucose anomers on the germination of dormant spores of Bacillus megaterium QM B1551 were studied, alpha-D-Glucose (1 mM) slightly initiated the germination of the dormant spores during 10 min incubation at 37 degrees C, while about 60% of the dormant spores became germinated with beta-D-glucose (1 mM) in the same conditions. From the above observations and the finding that only a trace amount of alpha- or beta-D-glucose may bind with the dormant spores, it is speculated that the beta-D-glucose-stereospecific receptor site for the germination exists on the surface of the dormant spores of the bacillus.

Bacillus megaterium↗