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Biomedical subjects

F Hazama

Publications and source records attributed to F Hazama.

133 records · Page 8Linked to original sources
PubMedDate not supplied

Changes of 5'-nucleotidase activity in cultured glioma cells.

Changes of 5'-nucleotidase (5'-N) activity during subcultivation of C6 clonal rat glioma cells were studied histochemically, cytochemically and biochemically. Two different cell populations were seeded with high or low cell density respectively. 5'-N activity in cultured cells increased continuously in both populations. The enzyme activity was always higher in the cells growing in high density than in those growing in low density, and this difference became statistically significant after 6 days of subcultivation. It seemed likely that the increase in 5'-N activity depended on cell density, not on the frequency of mitosis. Cytochemically, enzyme activity was detected on the outer surface of the plasma membrane of cell bodies or cell processes. Strong activity was found on the processes and cell membranes where cells touched each other. In the regions where cells had intimate cell-to-cell contact, marked elevation of the enzyme activity was seen. Increased 5'-N activity, which appeared to depend on cell density, was considered to be related with this cell-to-cell contact.

5'-Nucleotidase↗
PubMedDate not supplied

An animal model of cerebral aneurysms.

Cerebral aneurysms were induced experimentally in rats by ligating the common carotid artery on one side, making the animals hypertensive, and feeding them the lathyrogen beta-aminopropionitrile. On analysis of this experimental model, haemodynamic stress, hypertension and metabolic disorder of the connective tissue proved to be of primary importance as aetiological factors in the development of cerebral aneurysms. The experimentally induced cerebral aneurysms resemble those in man both in location and in microscopic structure; they can thus be regarded as a good model for the study of the pathogenesis of cerebral aneurysms. The initial changes leading to the formation of aneurysms occurred on the distal side of major artery branches adjacent to the apex, but distal to the intimal pad. It is proposed that degenerative changes in the internal elastic lamina and muscle cells of the media, caused by haemodynamic stress at vessel branches and intimal pads, are the basis for aneurysm formation.

Animals↗
PubMedDate not supplied

Analysis of secretion and expression of platelet-derived growth factor in cultured endothelial cells from stroke-prone spontaneously hypertensive rat.

1. We characterized the endothelial cell-derived growth factors of SHRSP and Wistar Kyoto rats (WKY), respectively and found that platelet-derived growth factor (PDGF)-B chain related growth factor constituted a major portion of the mitogenic activity of the conditioned media of endothelial cells from both animals. There were no remarkable qualitative differences between the endothelial cell-derived growth factors of SHRSP and WKY. 2. Northern analysis revealed that the expression of PDGF-B chain was 2-4-fold enhanced in cultured aortic endothelial cells of SHRSP. This enhanced expression of PDGF-B chain, which may be induced under chronic hypertensive conditions, is suggested to contribute to the increase in endothelial cell-derived growth factors reported in this animal.

3T3 Cells↗
PubMedDate not supplied

Scanning electron microscopic study of endothelial cells of cerebral arteries from spontaneously hypertensive rats.

Endothelial cells of the cerebral arterial system in spontaneously hypertensive rats were investigated by scanning electronmicroscopy and found to show progressive changes such as increased microvilli, numerous plasmalemmal pits, enlargement of the cells and well-developed marginal folds. Regressive changes, such as balloon-like protrusions and crater-like cave-ins, were also observed. Platelet adhesion to the injured endothelial surface of cerebral arteries was frequent. The significance of these changes in the development of hypertensive cerebrovascular lesions is discussed.

Aging↗
PubMedDate not supplied

Cerebral aneurysms and variations in the circle of Willis.

In order to obtain information about the relationship between variations in the circle of Willis and aneurysms, 44 complete circles of Willis with aneurysm were studied macroscopically. The incidence of variations was significantly higher in the aneurysm series than in the control circles without aneurysm. There was a definite correlation between asymmetric proximal segments of the anterior cerebral artery and aneurysms of the anterior communicating artery, and a tendency to correlation was found in the case of asymmetric posterior communicating arteries and aneurysms on the internal carotid artery-posterior communicating artery junction. In the light of these findings it seems likely that through hemodynamic changes variation in the circle of Willis plays some role in the development of cerebral aneurysms.

Cerebral Arteries↗
PubMedDate not supplied

Early changes of experimentally induced cerebral aneurysms in rats: scanning electron microscopic study.

To obtain information about the early changes of experimentally induced cerebral aneurysms in rats, the luminal surface of branching areas of their cerebral arteries was examined with a scanning electron microscope. At the branching sites of major cerebral arteries in the control animals, the intima just distal to the apex markedly protruded into the lumen forming a linear bank-like intimal pad. Along and distal to this pad, there was a shallow long groove (juxta-apical groove). Such grooves were much deeper and wider in experimental animals than those in the control rats. By studying various stages of early aneurysmal changes, cerebral aneurysms were proven to develop from such grooves. In deep juxta-apical grooves and small aneurysms, round regenerated endothelial cells with a large number of microvilli were diffusely present. Degenerated cells with balloons and craters were observed intermingled with such regenerated cells. Interendothelial gaps were also seen. The present study showed the complex structure of the apex of arterial bifurcation in rats, including bank-like intimal pads. Such complex structures of the branching sites were considered to be responsible for the initiation of cerebral aneurysms due to endothelial injury possibly caused by turbulent flow there.

Animals↗