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Biomedical subjects

A Koga

Publications and source records attributed to A Koga.

At least 109 records · Page 6Linked to original sources
PubMed1980

Influence of restricted diet on the cell cycle in the crypt of mouse small intestine.

Previously we reported that the small intestine of mice adapted to dietary restriction had low mitotic acitivty in the crypts. In that case there was no marked difference in the villus and crypt cell numbers, but the migrating speed from crypt to villus decreased, consequently the transit time was prolonged. The present study was undertaken in order to clarify whether or not the cell cycle of the proliferative cells in the crypts alters when the mitotic activity decreases. The results obtained in this study indicate that: 1) There are differences in cell cycle and labeling index between the unrestricted animals and restricted animals. 2) The cycle time of the duodenal and jejunal cells, particularly of G1 phase was prolonged under dietary restriction. 3) The prolongation of cycle time was not found in the ileum. It is thought that the proliferative cell number principally controls mitotic acitivity in the crypts. Still, reduction of the proliferative cell number will be accounted for by the increase of resting cells in G1 phase.

Animals↗
PubMed1978

Morphological and functional changes in the tight junctions of the bile canaliculi induced by bile duct ligation.

Thin sections after bile duct ligation showed that the depth of tight junctions appeared to increase and that the distance between individual punctate contacts appeared to become irregular and wider than in controls. The freeze fracture replicas clearly demonstrated these changes in the tight junction morphology. Changes were noted most conspicuously in the tight junction three weeks after ligation. Measurements of the junctional morphology in control and ligated specimens showed that the junctional depth had increased two fold in the latter, whereas the number of strands had scarcely changed. Lanthanum tracer experiments showed that the tight junctions did not permit the passage of the tracer in normal nor ligated rats. It was concluded that the mechanism of obstructive jaundice could not be related to changes in junctional morphology causing increased junctional permeability.

Animals↗
PubMed1978

Influence of restricted diet on epithelial renewal and maturation in the mice jejunum.

It has been known that the intestinal epithelial cell is characterized by a rapid cell turnover and by a gradient of differentiation from crypt to villus. The present study was undertaken to clarity the effect of diet on the migration and the maturation of the intestinal epithelial cells. The transit time from the crypt to the extrusion zone at the villus tip was determined with tritiated thymidine. To study the maturation of the cells the distribution of the terminal digestive enzymes, maltase [EC 3.2.1.20] and leucylnaphthylamidase E1EC 3.4.1.1], along the villus and crypt was analyzed quantitatively. And total activities of the same enzymes were assayed also in the mucosal homogenates. It was observed that the decrease in the migrating speed of villus cells was brought by energy restriction and the decrease in the migrating speed was associated with an increase of the enzyme activities in the upper zone of villus. And the result was that the intestinal epithelial cells which decrease in migrating speed by dietary restriction become more mature on the upper villus than those with unrestriced control.

Animals↗
PubMed1977

The influence of feeding patterns on the growth of rat.

To see the influence of a restricted diet and a meal feeding for the growing Wistar rats were subjected to three types of feeding patterns, free access feeding, three meals and one meal per day. The animals of each feeding pattern group were fed either unrestricted and restricted amount of diet. The restricted group received only 60% weight of the diet taken by the unrestricted groups. The growth of the animals having free access to the restricted amount of diet was almost similar to that of those having received the restricted amount of diet three meals per day rather than to the group fed the unrestricted diet once per day. The former group seemed to be a "nibbler type" rather than a "meal feeder type".

Animals↗
PubMed1975

Electron microscopic observations on the cholesterol distributed in the epithelial cells of the gallbladder.

Epithelial cells of eight human gallbladders with cholesterosis were examined. In the supranuclear portion of the epithelial cells of one case, many spicular, circular and plate-like crystalline structures are present. Spicular and circular structures have not a limiting membrane, but plate-like structures are apparently bounded by a limiting membrane that clearly shows trilamellar structure. After digitonin treatment, the spicular and circular crystalline structures become denser. On the other hand, the plate-like structures do not become denser by digitonization. In the epithelial cells that contain no crystalline structure, there also occur many reaction precipitates after digitonization. These findings may suggest that free cholesterol is highly present in the epithelial cells of gallbladder with cholesterosis and that it, in some case, precipitates in the form of spicular or circular structure for the rapid fixation process.

Cholesterol↗