Antibacterial activities of 3-di (hydroxymethyl) amino-6- [2- (5-nitro-2-furyl) vinyl] -1, 2, 4-triazine, (dihydroxymethyl furatrizine) were investigated using mutant strains of Escherichia coli lacking repair systems for DNA damage, i.e. polA, uvrA, uvrB, uvrC, recA, recB, recC and uvrArecA. All of the mutant strains were more sensitive to the drug than the parent strains, as was the case with the sensitivity to UV-irradiation. These results indicate that the drug acts lethally on sensitive bacteria by damaging their DNA, and parts of the damaged DNA are repaired by excision and recombinational repair systems. Filamentous cell formation was induced in all strains except the uvrArecA strain by sublethal concentration of the drug, as well as by UV-irradiation. It is possible that the occurrence of the short period of “unbalanced growth” induced by such DNA damaging agents leads to filament formation. In the cells of the double mutant, filament formation was induced by the drug but not by UV-irradiation, and the majority of the filamentous cells formed were multinucleated. This suggests that, in this double mutant, the drug directly reacts with the septation machinery of the cell envelope, resulting in filament formation. This hypothesis is supported by the electron microscopic observations that septation is interrupted in the filamentous cells induced by the drug.

View full abstract

Effects of each of three indigenous Lactobacillus groups on other bacterial populations were separately investigated in gnotobiotic rats. In the wall of the non-glandular part of the stomach, contents of the stomach and contents of the upper part of the small intestine, some pre-associated indigenous bacteria were reduced to conventional population levels by introducing three groups of lactobacilli : Group I (Lactobacillus acidophilus and related strains), Group II (L. fermentum) and the groups mixed. However, no obvious reduction in cell numbers of the pre-associated bacteria occurred in the case of Group III (L. murini).

View full abstract

Comparative studies on pathogenicity between Yersinia enterocolitica and Yersinia pseudotuberculosis were performed using experimental infection systems in vivo and in vitro.
All of thestra ins of both species successfully produced experimental enterocolitis in rabbits although the severity varied with the strains challenged. The changes were characterized by granulomatous lesions with necrobiotic centers in reticuloendothelial tissues of the intestine, mesenteric lymph nodes, liver and spleen.
These strains uniformly had the ability to penetrate HeLa cells and to survive or multiply within cultured rabbit peritoneal macrophages.
In addition, in infections with strain TP-2 or PST-III of Y. pseudotuberculosis, catarrhal inflammation all over the small intestine and/or focal necrosis and parenchymatous degeneration in the liver were observed, along with the granulomatous lesions. These strains, at the same time, exhibited cytotoxic effects on the cultured cells.
The pathogenic factors of Y. enterocolitica are discussed in comparison with those of Y. pseudotuberculosis.

View full abstract

When concanavalin A (1 μg/ml) or wheat germ agglutinin (2 μg/ml) was preincubated with a suspension of 2% rabbit erythrocytes for 5 min at 20 C, the binding of [¹²⁵I] -labeled staphylococcal alpha toxin to these erythrocytes was greatly inhibited and the hemolytic action of alpha toxin was decreased. The inhibitory effect of concanavalin A on hemolysis by alpha toxin was completely reversed in the presence of 0.1 M α-methyl-D-glucoside or α-methyl-D-mannoside. Phytohemagglutinin-P from Phaseolus vulgaris and soybean agglutinin inhibited hemolysis by the toxin at concentrations exceeding 20 μg/ml.
The effect of concanavalin A on alpha-toxin hemolysis was studied further to ascertain the nature of the inhibition. Double reciprocal plots were made of hemolysis against alpha toxin concentrations, and the data suggested that inhibition of the initial rate of the hemolysis by concanavalin A is competitive in nature. This was probably due to an interaction with the alpha toxin binding sites on the cell membrane surface.

View full abstract

The mitogenic activity of the cell-wall skeleton (CWS) of Nocardia rubraon purified splenic T-cells (thymus-derived lymphocytes) was investigated. N. rubra CWS showed remarkable mitogenic activity on normal spleen cells of C57BL/ 6J mice at concentrations ranging from 10 to 100 μg per milliliter of culture medium, while, on purified splenic T-cells, N. rubra CWS did not act as a mitogen at any concentration. However, mitogenic activity of N. rubra CWS on T-cells was restored if purified splenic T-cells were reconstituted with X-irradiated peritoneal exudate cells (macrophages). The above results suggest the necessity of macrophages for T-lymphocyte activation by N. rubra CWS as well as PHA-P or Con A.

View full abstract