Plasminogen activator content in heart tissue and perfusate under various experimental conditions.

In order to elucidate the mechanisms of plasminogen activator release into the circulation during the first minutes of experimental myocardial ischaemia in vitro, isolated rat hearts were perfused under optimal conditions and under conditions inducing myocardial ischaemia. In ventricular tissues the content of plasminogen a activator was measured; in the perfusate the plasminogen activator and anticoagulating activities were determined. Under optimal conditions the plasminogen activator content in contracting heart was found to be essentially the same as under in vivo conditions; in the perfusates the release of plasminogen activator and of substances possessing the anticoagulating activity was insignificant. Under myocardial ischaemia the release of these substances into the circulation increased, while plasminogen activator content decreased.

[Bacteriophage induction in cultures of C1. botulinum type A]. / Induktsiia bakteriofaga v kul'turakh C1. botulinum tipa A.

The authors describe the mitomycin induction of bacteriophages in strains No. 4/2, 98, and 345 of Cl. botulinum, type A. All the strains under study produced phages of the same morphology with a head and a process capable of contraction. The phages detected by electron microscopy failed to express any lytic activity on the strains of type A and other Cl. botulinum types neither in the fluid nor in the hard nutrient media. The data obtained supplemented and widened the view on the incidence of phage carrier state in the cultures of botulism causative agent.

[Detection of atoxigenic variants in Cl. botulinum type A and B cultures exposed to different treatments]. / Vyiavlenie atoksigennykh variantov v kul'turakh Cl botulinum tipov A i B pod vliianiem razlichnykh vozdeîstviî

A possibility of detection of atoxigenic clones in the cultures of Cl. botulinum, types A and B, under conditions of treatment with acridine strains, UV-irradiation and heating of spores was studied. Of the 10 strains investigated, atoxigenic variants were obtained only in 3, belonging to type B; the frequency of formation of atoxigenic clones under the effect of ethidium bronide constituted 36--45.7%, and of the UV-irradiation-4.2%; heating of spores proved to be ineffective. A frequent loss of the toxigenicity sign coincided with the view on the elimination of the episomal determinant of the toxin-formation, not with the mutational nature-of this change. An association between the differences in stability of retention of the toxigenicity signs in various strains and types of Cl. botulinum and possible differences of the corresponding genetic determinants of the toxin formation is discussed.