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Biomedical subjects

K Kohyama

Publications and source records attributed to K Kohyama.

23 records · Page 2Linked to original sources
PubMed1987

Naturally occurring CAR bacillus infection in a laboratory rat colony and epizootiological observations.

An epizootic of chronic respiratory disease was found in a rat colony. Lungs of the symptomatic rats showed histopathologically severe peribronchial lymphoid cuffing. Filamentous bacteria were detected on the border of the tracheal and bronchial epithelium by light and electron microscopy. These bacteria did not grown on artificial media but propagated in embryonated chicken eggs. The disease was thus diagnosed as cilia-associated respiratory (CAR) bacillus infection. Epizootiological observations of the natural and experimentally induced cases revealed that the disease was highly contagious, slowly progressive and intractable. Contact infection may play a major role in the transmission of this disease.

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PubMedDate not supplied

Hepatocyte regeneration after partial hepatectomy occurs even under severely thrombocytopenic conditions in the rat.

In order to investigate the role of blood platelets in regenerative proliferation of hepatocytes in vivo, partial hepatectomy was carried out under conditions of severe thrombocytopenia achieved by X-irradiation and the time-dependent degree of hepatocyte regeneration was measured as labeling index (LI) after 3H-thymidine injection. LI values reached a maximum 36 h after hepatectomy performed 7 days subsequent to a whole-body irradiation of 7.5 Gy, although the maximum rate was found to be only about one-third of that found in unirradiated control rats. At this time point, the number of peripheral blood platelets was decreased to about 2% of that of unirradiated controls and bone marrow megakaryocytes were virtually undetectable. A decrease of LI, similar to that found for the whole-body irradiation in degree, was also observed after local irradiation of the liver with the same dose but without an apparent decrease in platelets. When whole-body irradiation was performed with the liver shielded, under which conditions the numbers of blood platelets decreased to about 8% of the control levels, almost no decrease in LI was found. The results thus suggest that the observed inhibition of hepatocyte regeneration was directly due to liver irradiation and that depletion of blood platelets itself does not interfere with the regeneration process, providing evidence against a dominant role of the platelets in the regeneration as proposed by other authors.

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PubMedDate not supplied

Polysaccharide-protein interaction: a rheological study of the gel-sol transition of a gelatin-methylcellulose-water system.

Viscoelastic parameters for mixtures of gelatin and methylcellulose were measured as a function of temperature, in order to study the gel-sol transition of the system in which biopolymers forming thermo-setting and thermo-melting gels coexist. At higher temperatures than 45 degrees C, the gel network is mainly formed by methylcellulose while at lower temperatures around 5 degrees C, it is mainly formed by gelatin. At higher temperatures than 45 degrees C, gelatin inhibits the gelation of methylcellulose. A small amount of methylcellulose helps gelatin to form a network at lower temperatures. However, excessive amounts of methylcellulose inhibit the growth of network structure. Therefore, this mixture forms a phase separated gel at higher temperatures while it is not completely phase separated at lower temperatures, probably by some interaction between non-substituted hydroxyl groups in methylcellulose with carboxylic groups in gelatin.

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