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Biomedical subjects

K Kanai

Publications and source records attributed to K Kanai.

At least 253 records · Page 14Linked to original sources
PubMed1976

Isolation and characterization of hydrophobic proteins (H proteins) in the membrane fraction of Bacillus subtilis. Involvement in membrane biosynthesis and the formation of biochemically active membrane vesicles by combining H proteins with lipid.

Cytoplasmic membranes of Bacillus subtilis, grown in complex medium containing glucose, were fractionated into three membrane subfractions [light band (1.155 - 1.158 g/cm3); medium band (1.181 - 1.183 g/cm3); heavy band (1.21 - 1.25 g/cm3)] by sucrose density gradient centrifugation. Among these subfractions, the light and medium bands consisted mainly of membranes but the heavy band consisted of an irregular arrangement or aggregate of small globular protein components of 5 - 8 nm in diameter. We named this H-protein. H-protein formed trilamellar unit membrane structure when combined with lipid. In pulse-labeling and pulse-chase experiments with radioactive leucine, it was found that H-protein consisted of the newest membrane protein synthesized in the cells and the label incorporated into H-protein was shifted into light and medium band of the membranes during the chase. Cytochromes were not found in H-protein. However, when H-protein was incubated with haem alpha and protohaem, these compounds were incorporated into the apoproteins of the cytochromes present in H-protein and form cytochromes a and b. Cytochromes were also formed in H-protein which were isolated from the cells grown in the presence of haemin (haemin-grown H protein). Succinate dehydrogenase activity was increased about 4-fold by combining H-protein or haemin-grown H protein with lipid. H-protein had no cytochrome oxidase activity; however, haemin-grown H protein was found to have some of the activity and this was increased about 4-fold by combining the protein with lipid. Haemin-grown H protein was also found to form succinate: cytochrome c oxidoreductase when combined with lipid and vitamin K2. On the other hand, succinate oxidase was required for the addition of lipid, vitamin K2 and cytochrome c. NADH oxidase was also found in haemin-grown H protein and was activated about 9-fold in constituted reaction systems. Vesicles formed by haemin-grown H protein and lipid, could accumulate alanine and proline by addition of NADH or reduced phenazine methosulfate. Alanine and proline was also accumulated into the vesicles when transport energy was supplied as a membrane potential introduced by K+-diffusion via valinomycin. These results would indicate that H-protein contains the apoprotein of cytochromes, and a carrier involved in the active transport of alanine and proline.

Alanine↗
PubMed1976

An attempt to cultivate mycobacteria in simple synthetic liquid medium containing lecithin-cholesterol liposomes.

An attempt was made to cultivate mycobacteria in a simple synthetic liquid medium containing lecithin-cholesterol liposomes. This lipid complex showed a marked growth-promoting effect on the submerged growth of M. tuberculosis and M. bovis. The role of lecithin as nutrient was suggested. The bacillary growth in such environment retained good viability, strong acid-fastness, and high virulence in mice. An avirulent strain of tubercle bacilli, H37Ra, did not respond to lecithin-cholesterol liposomes unlike the parent virulent strain, H37Rv. However, this was not a general rule for virulence, as a highly virulent strain of M. bovis (Ravenel) and an attenuated strain (BCG) both grew well in the presence of lipsomes. Lipid analysis showed that cholesterol in the liposome medium was esterified to some extent during the bacterial growth. It was discussed that the culture in the liposome-containing medium may present an experimental model for the study of interaction between mycobacteria and the macrophage membrane.

Animals↗
PubMed1976

Accumulation of cholesterol esters in macrophages incubated with mycobacteria in vitro.

Macrophages separated from the granulomatous lungs of tuberculous mice had a high amount of cholesterol esters. Resident peritoneal macrophages of normal mice were very low in the ester content. However, when the cells were incubated with mycobacteria in Hanks' solution the ester content of the mixture increased greatly. Peritoneal macrophages harvested by induction with casein had a much larger amount of cholesterol esters than unstimulated resident cells. When such stimulated macrophages were incubated alone in Hanks' solution, the ester content went down probably due to hydrolysis into free form. This reduction was markedly inhibited by incubation with mycobacteria. These observations at a macrophage level presented a cytological explanation for our previous finding that cholesterol ester content increased in the mouse lungs with the development of granulomatous lesions.

Animals↗
PubMed1976

A suggested role of a host-parasite lipid complex in mycobacterial infection.

On the basis of our previous observations and related literatures, was assumed tht cholesterol esters of host origin and phthiocerol dimycocerosate of bacterial origin are located as a lipid mixture around the periphery of pathogenic mycobacteria growing in vivo, probably within the phagocytic vacuole of macrophages. To examine the role of such a postulated lipid complex in mycobacterial infection, a model experiment was made in which tubercle bacilli grown in vitro were "coated" with both lipids and then suspended homogenously in water to serve as an inoculum to infect mice intravenously. Their fate in mouse tissue was compared with that of untreated control bacilli. The results indicated that the lipid "coating" had an infection-promoting effect as revealed by the longer persistence of the treated avirulent bacilli at higher levels of viable counts. When virulent tubercle bacilli were "coated" with the lipid mixture, they became less sensitive to the protective mechanism of BCG-immunized mice.

Animals↗
PubMed1976

Further studies on the lethal effect of long-chain fatty acids on mycobacteria.

Mycobactericidal activity of long-chain fatty acids was confirmed by in vitro exposure of BCG. The killing effect was accompanied by inhibition of the membrane-bound acid phosphatase activity. Such active fatty acids were those having a stronger hemolytic activity (e.g., C12:0, C14:0, C18:1, C18:2). Heat-killed BCG cells or their cell walls adsorbed the toxic fatty acids, whereas the fatty acid-insensitive E. coli cells did not. It was suggested that the mycobactericidal action of long-chain fatty acids is due to their detergent-like action on the cytoplasmic membrane, and that the determinant factor for the fatty acid-sensitivitiy of bacteria is the property of the cell wall by which fatty acids are adsorbed so that the active site is brought into contact with the inner membrane.

Acid Phosphatase↗
PubMed1975

Synthesis of alpha-fetoprotein by rat ascites hepatoma cells.

AH-66 rat ascites hepatoma cells incorporated [14C]leucine into the AFP fraction. In a cell-free system, hepatoma ribosomes were found to be active in AFP synthesis whereas the supernatant fraction from hepatoma had no specific effect on AFP production. The amount of [14C]leucine incorporated in AFP by membrane-bound polysomes was 20 to 90 times higher than that by free polysomes, suggesting that AFP is mainly synthesized on membrane-bound polysomes. DBcAMP inhibited the growth of hepatoma cells. However, the incorporation of [14C]leucine into the AFP fraction as well as into total proteins was stimulated by DBcAMP.

Animals↗