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Biomedical subjects

T Hara

Publications and source records attributed to T Hara.

At least 1,099 records · Page 61Linked to original sources
PubMed1982

Importance of the antigen-binding valency and the nature of the cross-linking bond in ricin A-chain conjugates with antibody.

As a continuation of our work on toxin A-chain conjugates with antitumor antibodies for selective delivery of the toxin to the target cells, four ricin A-chain conjugates were prepared by linking A-chain to Fab' or F(ab')2 of rabbit IgG against L1210 with or without employing a cross-linking agent, N,N'-o-phenylenedimaleimide (PDM), N-succinimidyl 3-(2-pyridyldithio)propionate (SPDP) or N-succinimidyl m-(N-maleimido)benzoate (SMB), and the effects of antigen-binding valency and of the nature of the cross-linking bond on their in vitro cytotoxicity were studied. The relative potencies of the conjugates in terms of IC94's were as follows: F(ab')2-SPDP-A-chain, 100; Fab'-S-S-A-chain, 21; F(ab')2-SMB-A-chain, 1.3; Fab'-PDM-A-chain 0.38. Among the four conjugates, F(ab')2-SPDP-A-chain and Fab'-S-S-A-chain can be cleaved into the homing and the cytotoxic components with 2 mM 2-mercaptoethanol. These results suggest that divalency in antigen-binding and susceptibility of the cross-linking bond to cleavage by mercapto reagent are desirable for high potency. Protein synthesis in a cell-free system of rabbit reticulocyte lysate was inhibited by Fab'-S-S-A-chain and by Fab'-PDM-A-chain as effectively as by free A-chain, indicating that the liberation of A-chain is not important, at least on ribosomes, but it is important for the A-chain to reach a ribosome after binding of the conjugates to the cell-surface.

Animals↗
PubMed1982

Elimination of plasmid-linked polyglutamate production by Bacillus subtilis (natto) with acridine orange.

Treatment of Bacillus subtilis (natto) strains Asahikawa, F, and M with acridine orange resulted in the conversion of approximately 64.2% of the Asahikawa population, 22.4% of the F population, and 9.2% of the M population to polyglutamate-nonproducing colonies. Such curing is suggestive of the involvement of plasmid DNA. Samples of cleared lysates of both parental and their cured strains were subjected to agarose gel electrophoresis to determine the plasmid composition. Parental strains were found to possess a plasmid, but polyglutamate-nonproducing derivatives were missing the plasmid. The plasmid-linked polyglutamate production, which was originally isolated from B. subtilis (natto), could be transformed in B. subtilis.

Acridine Orange↗
PubMed1982

The lethal protein from Kintoki beans (Phaseolus vulgaris) identified as a lectin.

A glycoprotein isolated from Kintoki beans (Phaseolus vulgaris cultivar Kintoki) agglutinated human erythrocytes of all types and erythrocytes of rat, rabbit, sheep, and mouse. The lectin activity was not affected by 1 hr heating at 60 degrees C, but decreased slightly on heating for the same period at 70-80 degrees C and markedly at 90-100 degrees C. The activity was inhibited by galactose, lactose, N-acetyl galactosamine and fetuin. The inhibition was, however, weak, as often found for nonspecific lectins. The activity did not change when tyrosine residues or small parts of amino groups were modified, but decreased considerably when histidine residues or carboxyl groups were modified. This lectin was found to be relatively resistant to trypsin, and, particularly, to pepsin. All mice died within 48 hr when 200 microgram lectin per gram body weight was injected intraperitoneally and 14 microgram intravenously. The toxic activity changed in parallel with the lectin activity upon various treatments of the glycoprotein. In addition, blood analyses of injected mice suggested that the toxicity might be developed by the action of the lectin on blood cells.

Animals↗
PubMed1982

An inhibitor of (Na+, K+)-ATPase produced by Streptomyces pseudovenezuelae MF722-02; purification and properties.

A culture product of Streptomyces pseudovenezuelae MF722-02, with a molecular formula of C29H32N2O7, was isolated as yellow needles from culture broths and mycelia of the organism by means of a series of solvent extraction, column chromatography and crystallization. The antibiotic is active against some Gram-positive bacteria, inhibits growth in vitro of cells of mouse leukemia L-1210, prolongs the life span of mice inoculated with the leukemia cells, enhances deoxycholate-induced hemolysis in vitro and inhibits (Na+, K+)-ATPase in vitro.

Animals↗
PubMed1981

Electron microscopy of E-rosette-forming leukemic monocytes in a child with acute monocytic leukemia.

A 7-year-old boy with acute monocytic leukemia (AMoL) had leukemic monocytes that formed spontaneous rosettes with sheep red blood cells (E-rosette). The E-rosette formation was observed in 75% of leukemic monocytes at 4 C and in 37% at 37 C. Cytochemical and ultrastructural studies confirmed that the rosette-forming cells were leukemic monocytes. The leukemic monocytes attached to the red blood cells at a portion of their surface and did not show any phagocytic processes at the electron microscopic level. The data from this patient seem to indicate that in a rare case of AMoL, abnormal myeloid lymphoid stem cells can differentiate to monocytes while retaining lymphoid properties.

Child↗