Redwood DR, Epstein SE: Prevalence and characteristics of disproportionate ventricular septal thickening in patients with acquired or congenital heart diseases: Echocardiographic and morphologic findings. Circulation 55: 341, 1977

No abstract

An interference phenomenon was produced by the intraperitoneal injection of broth culture dilutions of Pasteurella pestis grown at 28° C. into small white rats.At a critical level of approximately 106Past. pestis L37 marked interference was produced. Doses of 104 or 107 killed rats readily.Interference was produced by the addition of killed organisms, a cell-free vaccine or a live vaccine, to small lethal doses of L37.Non-specific interference was produced by the intravenous injection of Indian ink prior to the intraperitoneal challenge with Past. pestis L37.

No abstract

SUMMARY: After exposure to phage AT an organism of an indicator strain of Salmonella typhirnurium may burst with phage liberation, may become lysogenic, or may develop into a mixed progeny of lysogenic and phage-sensitive bacteria. By the methods we have used, the proportion of such mixed progenies is about 20% of the number of lysogenic colonies found. Evidence is given to show that members of the clone of phage A1 vary in virulence and that members of the indicator strain 1404 vary also in resistance to lysis. The establishment of lysogenesis depends on the interplay of these two factors when host and parasite meet. The reaction of certain phages of Salmonella typhimurium with their host has been studied by Boyd (1951 b). He regards a phage lysate as being a mixture of two kinds of particle: alpha particles which establish a state of lysogenesis (symbiosis) with an indicator organism, and beta particles which lyse the bacterial cell. Boyd postulates that the symbiotic state is the dominant one and therefore an organism exposed to an alpha particle (or to an alpha plus one or more beta particles) becomes lysogenic. While attempting to confirm these views, a type of colony was observed, infected with phage, and showing a central punctate nibbling. This phenomenon did not seem to arise as a result of the edge of a growing colony impinging on a free phage particle (Pl. 1, figs. 1 and 2). If this type of centrally nibbled colony could be shown to arise from a single cell the inception of lysogenesis in an indicator strain must be more complex than can be accounted for by Boyd's alpha and beta particle hypothesis. Lwoff & Gutmann (1950) who studied Bacillus megaterium, suggested that all the particles of phage in a lysate are alike and that the inception of a state of lysogenesis is due to a phage particle coming into contact with a resistant bacterium; the phage enters the bacterium and develops to the stage of prophage but no further. Neither theory fits our findings. Our results suggest that bacteria exposed to phage can either burst, or become lysogenic or recover from phage infection, according to the virulence of the phage particle and the resistance of the host it encounters. MATERIALS USED(1) Lemco broth. 1 % Lemco in 1 % peptone water with 0.5 % sodium broth culture of strain 1404/A1 which had been heated at 59" for 1 hr.