George M. Hass

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Skeletal myofibrils isolated either by tryptic digestion at 0 degrees C. or by a colloid mill and suspended in buffer solution (pH 7.0, micro; 0.154) containing 20 per cent glycerin and 0.0025 M adenosinetriphosphate at -5 degrees C. contracted slowly and progressively when the temperature was raised above 0 degrees C. Formalin fixation halted this(More)
Several methods for the experimental study of the rickettsial diseases have been applied to fièvre boutonneuse. An analysis of the results has indicated that fièvre boutonneuse is a variety of spotted fever and that the etiologic agent is a rickettsia which belongs to the genus Dermacentroxenus and to the species rickettsi (Wolbach (6)). The distinctive(More)
Twenty-five pairs of male rabbits of the same variety and strain were joined together in aural parabiosis for 13 to 15 days and then separated from one another. Thirteen pairs of the separated parabiotic twins were surgically united for a second period of parabiosis, less successful than the first due to deficient healing and spontaneous separation of(More)
Simultaneous autologous and homologous musculofascial transplants were made in New Zealand white rabbits. The basic pattern of degeneration and granulation tissue organization of both types of transplant was essentially identical. The superposition of two reactions in the framework of organizing granulation tissue served to distinguish homologous from(More)
In tissue cultures grown at 32 degrees C., typhus Rickettsiae increase rapidly within the cytoplasm of infected cells up to about the 14th day. At this time practically every cell is infected and the majority of cells are distended with organisms. This condition remains constant as long as successful cultures of the cells can be maintained (up to 52 days).(More)
Spotted fever infection has been studied in tissue cultures grown at 32 degrees C. The behavior of spotted fever Rickettsiaeis compared and contrasted with that of typhus Rickettsiae under similar conditions. The spotted fever organisms multiply extensively in the nuclei of cells where they form spherical clusters of various sizes. These structures are(More)
A new method for the isolation of large numbers of individual myofibrils from fresh mammalian skeletal and cardiac muscle has been described. Purification of isolated myofibrils was accomplished by differential centrifugation of fresh frozen sections of muscle which had been mechanically agitated after exposure for 30 to 45 minutes at 0 degrees C. to the(More)
Under ordinary conditions musculofascial cross-grafts made between pairs of rabbits of the same strain and species elicited classical host-homograft tissue interactions. When the cross-grafting was done 7 to 10 days after exchange transfusions leading to introduction of about 40 per cent of foreign blood, the classical host-homograft reaction failed to(More)
American strains of typhus (Mooser (1), Maxcy (2)) differ from European strains (Nicolle (3), Wolbach (4)) chiefly in the fact that the former produce a severe acute inflammation of the scrotal sac in laboratory animals. In a previous paper (5), attention was called to the occurrence of a periodic scrotal sac exudate in guinea pigs inoculated with the(More)
Typhus Rickettsiae are found in large numbers in sections of tissue cultures of scrotal sac exudate. Extensive multiplication of the organisms occurs, and new cells become infected. Organisms are seen in cells undergoing mitotic division. The organisms usually become less numerous after the 6th day in vitro, but in one instance organisms were extremely(More)