The extraction of antigens (trichophytin) from
Trichophyton mentagrophytes
var.
asteroides
grown in both a complex medium and a defined medium proved to be reproducible and feasible. These extracts were first evaluated by skin testing in both infected and noninfected guinea pigs. Further evaluation and standardization was accomplished in selected humans by comparing these antigens to a trichophytin known to elicit allergic reactions to the dermatophytes. The trichophytins produced by this extraction procedure gave no false positive (or negative) skin test reactions. These antigens did, however, reliably elicit allergic sensitivity of both the immediate and delayed type. The potency of both complex and defined media antigen was shown to be equal to that of the standard trichophytin.
Spores of Bacillus subtilis were produced in the presence of several cationic compounds. Thermal-destruction studies revealed that cationic compounds increased heat resistance of the spores. Of the compounds tested, lysine-rich histone, isolated from calf thymus, afforded the greatest degree of protection against moist heat at 100°.
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