In Japan, one strain of L. australis A was isolated in 1937 from a patient of so-called autumn fever in Shizuoka prefecture. A second strain of this type was obtained in 1953 from a human case of iritis in Kochi prefecture. In 1955, isolation of a third strain was successful in a case of bovine hemoglobinuria in Hyogo prefecture and that of 3 more strains in dogs in Ehime prefecture. These 6 Japanese strains were found to be identical with the Ballico strain in agglutinin- absorption tests. Therefore, in Japan, the distribution of L. australis A in man, cattle, and dogs has been ascertained.

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Endotoxins of various bacteria, prepared by the same method, were compared as to their effect on circulating platelets as well as on the other cellular constituents of blood of rabbit by a single intravenous injection of 100μg per kg.
(1) Endotoxins of Shigella flexneri 2a, 2b, 3a, and Shigella sonnei showed a powerful effect of decreasing the circulating platelets. The recovery took place slowly and even after 24-48 hours the number of circulating platelets shows a decrease.
The endotoxin of Escherichia coli FCS80, Salmonella typhi strain Chiba, and Saccharomyces cerevisiae showed also a transient decrease of circulating platelets during first 2-4 hours but the effect was weaker as compared with shigella endotoxin and full recovery took place within 4-24 hours after the injection. The endotoxin of Staphylococcus aureus 209P and Mycobacterium tuberculosis strain Aoyama showed no recognizable effect on the number of circulating platelets by administration of 100μg per kg.
(2) The circulating erythrocyte showed a slight and transient increase in number in the first 1-4 hours after the administration of shigella and Salmonella typhi endotoxin and rapidly returned to the starting value. In some cases a slight decrease was shown. The endotoxin of the other bacteria showed no appreciable change.
(3) The circulating leucocyte showed leucopenia in the first 1-4 hours and a remarkable leucocytosis 24 hours after the administration of shigella endotoxin. The endotoxin of Escherichia coli FCS80, Salmonella typhi, Staphylococcus aureus 209P, Mycobacterium tuberculosis strain Aoyama, and Saccharomyces cerevisiae showed also a slight initial leucopenia followed by slight or no leucocytosis.
(4) A crude correlation between the highest incidence of a critical condition in the initial stage of infection of Shigella paradysenteriae and sonnei and the strongest effect of these bacteria on the circulating platelets and leucocytes was observed in this experiment suggesting the importance of further investigation as to its significance.

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(1) Endotoxins of Shigella flexneri 2b and 2a induced the appearance of a certain amount of HT (5-hydroxytryptamine) in the plasma of rabbits after an intravenous administration of 1-5mg. This was confirmed and estimated using the chromatographic technique and the concentration of HT was estimated as 0.004 to 0.01μg per 1cc of 3 specimens of all 5 plasmas tested 1-2 hours after the admisnistration. In the plasma of all 5 normal rabbits was found no detectable HT.
(2) 5 of 9 test specimens of heparinized plasmas and 3 of 10 test specimens of serum sampled after the administration of 100μg-5mg per kg of Shigella flexneri 2a and 2b to be endotoxin were found definitely to cause platelet-agglutination, whereas all of 12 test specimens of normal plasma and all of 19 test specimens of normal serum showed no effect on platelets.
(3) The appearance of HT in the plasma after the administration of bacterial endotoxin discovered by the present investigation was con sidered to be due to the release of HT from platelets clumped by endotoxin.
The relationship of the release of HT from the platelets, especially from the platelets thrombi on the wall of capillaries, to the ultimate local vasoconstriction, increased permeability, and damage of blood vessel as well as of the adjoining organ, resulting finally in circulatory shock, was newly proposed.

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BOL₁₄₈, a well-known HT antagonist, and heparin, which are known to prevent the release of HT from platelets associated with blood clotting were administered to rabbits to see the preventive effect of toxicity of endotoxin of Shigella flexneri 2b, 2a, and sonnei.
Iproniazid, a monoamine oxidase inhibitor, which is known to inhibit the enzymatic destruction of HT in the body and as a consequence to promote the effect of HT, was also administered prior to the administration of the endotoxin to see the promoting effect of toxicity.
(1) BOL₁₄₈ administration, 60μg per kg intravenously or 500μg per kg subcutaneously, started immediately after the administration of shigella endotoxin in 13 rabbits, inhibited the appearance of diarrhrea, hyperemia of skin and eye, and diminished the appearance of petechia of conjunctival membrane and prolonged the death of animal, but it was not enough effective to prevent the fatality significantly.
In another group of 18 rabbits 1mg per kg of endotoxin of Shigella sonnei was administered. All 9 animals without BOL₁₄₈ died within 24 hours. 3 animals, received two shots each of 500μg per kg BOL₁₄₈, failed to show any beneficial effect. While in 6 animals, receiving two shots each of 1mg and 1.5mg per kg BOL₁₄₈, a benefical effect was observed and 3 of 6 animals survived over 48 hours.
(2) Heparin administration 15mg per kg intravenously started immediately after the administration of shigella endotoxin decreased significantly the fatality rate and diminished the symptoms induced by endotoxin.
(3) Iproniazid administration orally 75mg per kg prior to the administration of the sublethal dose of endotoxin of Shigella flexneri 2b in 6 rabbits promoted significantly the toxicity and also promoted the lethality of the endotoxin. 3 animals died within 12 hours and the 3 surviving animals showed ataxic gait whereas 6 control animals survived over 48 hours without apparent symptoms.
These evidences, indicating the preventive effect of BOL₁₄₈ and heparin against the toxicity of shigella endotoxin and the promoting effect of iproniazid on its toxicity, may suggest the important role of HT released from platelets by endotoxin in its toxicity.

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