[The effect of experimentally induced histamine deficiency on growth and rate of taking of model tumours (author's transl)].

From oncolytically effective clostridial strains, the intact washed or fractionated material of the spores and vegetative forms and culture media were examined for histamine decomposing activity in previous in vitro experiments (14). In a fractionated state, all strains cause a reduction of histamine activity. Therefore histaminases are present as endozymes. When the spores germinate to vegetative forms on the tumour following i.v. injection, the cell wall breaks open and the enzymes are released. Möse et al. (13) described rapid and nearly complete decomposition of plasmakinins (specifically bradykinin) by means of the above mentioned special preparations of clostridial strains with oncolytical effect (culture media partially excepted). Bradykinin and histamine are vasoactive substances, which are significant in terms of fine regulation of the capillary circulation. Continuous inactivation of these tissue hormones effected by the (clostridial) vegetative forms concentrated in the tumour may decrease the capillary circulation and thereby favour necrotization or decomposition of the tumour. In this animal experiment the effect of this biogenic amine on growth and rate of taking of tumours by means of artificially produced changes in the flowing equilibrium of the histamine metabolism was to be shown. Mice: While feeding mice a pyridoxal phosphate-free diet, a Harding-Passey melanoma was inoculated: The tumour weights were slightly lower in the case of animals put on the diet than in controls. Rats: Histamine-free diet and treatment with semicarbazide (in the course of the treatment implanzation of a Walker tumour). The taking of the tumours was significantly delayed or their growth reduced as a result of the diet or the treatment with semicarbazide or both.