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J P RANSOM

Publications and source records attributed to J P RANSOM.

15 recordsLinked to original sources
PubMed1962

Effect of a reticuloendothelial stimulating agent (restim) on resistance of mice.

Ransom, John P. (New England Institute for Medical Research, Ridgefield, Conn.), Varsenig Z. Pasternak, and John H. Heller. Effect of a reticuloendothelial stimulating agent (restim) on resistance of mice. J. Bacteriol. 84:466-472. 1962.-The effect of restim, a preparation of yeast cell walls, on resistance of mice to challenge by Salmonella typhimurium has been investigated. Although restim markedly increases the rate of phagocytosis and clearance of carbon particles, and presumably of viable bacterial cells, this activity has no significant effect on the course of events when restim-treated mice are challenged with S. typhimurium. However, when specific antibody derived from either active or passive immunization of the mice is present, restim significantly enhances resistance as judged by survival time and by 20-day survival.

Animals↗
PubMed1960

Non-specific resistance to experimental cholera in embryonated eggs.

It has been confirmed that 11- and 13-day-old chick embryos are susceptible to lethal infection with minute inocula of V. cholerae, while 15-day-old embryos are relatively resistant. Twenty strains of E. coli were found to vary in their capacity to kill chick embryos, without relationship to their human enteropathogenicity. Prior infection of 13-day-old embryonated eggs with E. coli strains selected for low embryo virulence had a marked protective effect against superinfection with V. cholerae. This effect was duplicated by pretreatment of embryos with killed E. coli cells or endotoxin preparations but not with a suspension of killed cells of a Gram-positive species. Preparatory E. coli infection induces a phase of vibriostasis in the 13-day-old egg which may be sufficient to tide the embryo over into the phase of relative insusceptibility associated with age. Younger embryos exhibit only a lag in death under similar conditions. The chick embryo is presented as a potentially valuable tool for the study of combined infections and of the mechanisms of natural resistance.

Animals↗