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Biomedical subjects

K Kanai

Publications and source records attributed to K Kanai.

At least 199 records · Page 11Linked to original sources
PubMed1982

Development of ultrastructural heterogeneity among hepatocytes in the mouse.

Ultrastructural stereological analyses of periportal and centrilobular hepatocytes of newborn, 5- and 10-day-old, and adult male ddY mice were carried out to study the postnatal development of the morphologic heterogeneity among hepatocytes. In newborn animals, the periportal and centrilobular cells did not differ in the volume densities of the smooth and rough endoplasmic reticulum; in the volume and numerical densities of the mitochondria, lysosomes, peroxisomes, and lipid droplets; or in the shape (the axial ratio) of the mitochondria. In 5-day-old animals, the volume densities of the mitochondria and rough endoplasmic reticulum were greater in periportal cells than centrilobular cells, and the volume density of the smooth endoplasmic reticulum was greater in centrilobular cells than periportal cells. In 10-day-old animals, a further difference was seen in the numerical density of the mitochondria, which was greater in centrilobular cells than periportal cells. Adult hepatocytes showed also a difference in the axial ratio of the mitochondria, which was greater in centrilobular than periportal cells; there was no difference in the volume density of the rough endoplasmic reticulum. When the data were expressed as volume and number per hepatocyte, the patterns of sublobular distributions of these organelles differed from the patterns seen in the volume and numerical density data, mainly in adult animals. This difference was caused by the marked increase in hepatocyte volume between 10 days of age and adulthood, especially in centrilobular cells. The results show that, in general, the ultrastructural heterogeneity among hepatocytes, evident in adult animals, is not present in newborn animals but arises during postnatal development, and suggest the occurrence of a lobular gradient in postnatal development of hepatocyte functions.

Animals↗
PubMed1982

Electron microscopic demonstration of close contact between intracellular mycobacteria and the phagosomal membrane.

Ultrathin sections of granulomatous lung lesions of tuberculous mice were subjected to electron microscopy to observe the intraphagosomal behaviour of mycobacteria. The close contact between the external surface of the bacterial cell wall and the phagosomal membrane was a characteristic feature, This was also observed with ultrathin sections of a mycobacterial specimen harvested from the homogenate of such lungs. The significance of this event was interpreted in relation to the mechanism of mycobacterial infection.

Animals↗
PubMed1982

A novel type of lymphocyte-macrophage association revealed electron microscopically in tuberculous lung lesions of mice.

Electron microscopic survey of tuberculous lung lesions of mice revealed a novel type of lymphocyte-macrophage association. The finger-like projections with sharp or blunt tips of lymphocytes area formed as if pushing deeply the macrophage membrane to form pockets matching the shape of the projections. Intimate membrane contact occurs between these two cells, particularly at the leading edges. The biological significance of this morphological event remains to be a subject for future study.

Animals↗
PubMed1981

An electron microscopy study of intra-cellular mycobacteria in experimental mouse tuberculosis.

Ultra-thin sections for electron microscopy (EM) were prepared from granulomatous lungs which developed in mice in response to experimental infection by a highly virulent strain of M. bovis. A subsidiary study was made of the EM appearance of mycobacteria separated from the lung tissue homogenate by differential centrifugation and trypsin-digestion. Examination of many micrographs showed that the phagosomal membrane may, at least partly, be in close contact with the cell wall of ingested mycobacteria. Such areas of contact often produce an electron-dense granularity or a row of evenly-spaced minute granules, accompanying the damage to the inner structure of the bacterial cell. A variety of disintegrating bacterial figures were observed, characterized by inward detachment of the plasma membrane, shrinkage and digestion of the cytoplasm, and occasional rupture of the cell wall. Various forms of lamellated and osmophilic inclusion bodies were present in macrophages, but their relation to ingested mycobacteria was uncertain.

Animals↗
PubMed1981

Increased histone acetylation and deacetylation in rat ascites hepatoma cells.

Rates of histone acetylation and deacetylation in nuclei from fetal, adult, and two kinds of neoplastic rat hepatocytes were examined. Histone acetylation in isolated nuclei was measured in the presence of 6 mM sodium n-butyrate, a potent inhibitor of deacetylase, and in the absence of the inhibitor. The deacetylase activity was estimated from the difference between the rates with or without the inhibitor. Both histone acetylation and deacetylation in nuclei from hepatoma cells (AH 66 cells) occurred two times faster than those of nuclei from fetal and adult livers regardless of alpha-fetoprotein production. This increased acetylation and deacetylation in hepatoma cells may be ascribed to either the increased activities of the enzymes or the increased accessibility of histone to the enzymes in the chromatin. Autoradiographic analysis of acetylated histones showed that all of the internal histones of the nucleosomes were acetylated and that apparent difference was found in the pattern of acetylated fractions between hepatoma nuclei and normal liver cell nuclei.

Acetylation↗