The present investigation was designed to study the distribution of enzymes in the mamillary body in detail: The latest histochemical methods were applied to the rabbit brain. In the medial nucleus, the nerve cells and the neuropil showed strong succinate dehydrogenase and strong cytochrome oxidase reactions. In the lateral nucleus, the strong reactions were found in the perikaryon of the nerve cells, while the neuropil was weakly or moderately active. The neuropil exhibited fairly strong aldolase activity in the medial nucleus except a thin lowermost layer. In the lateral nucleus, moderate aldolase reaction was almost confined to nerve cells. Strong glucose-6-phosphate dehydrogenase activity was observed in the perikaryon of the nerve cells of the lateral nucleus, while the neuropil of the medial nucleus showed no strong reaction. The neuropil of the lateral nucleus exhibited stronger amylophosphorylase reaction than that of the medial nucleus. The neuropil of the thin lowermost layer of the mamillary body showed moderate or rather strong monoamine oxidase activity and weak aldolase activity. It is interesting that the neuropil of the lateral nucleus which seems to produce less energy compared with that of the medial nucleus exhibited a little higher activity of cholinesterase than that of the medial nucleus or the same as the latter.

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Beef liver catalase was oxidized by performic acid in the presence of 8 M urea. A complete cleavage of –S-S- linkages was confirmed by amino acid analysis of performic acid-oxidized catalase (PC). Molecular weight of PC in 8 M urea-1 M HCOOH-0.1 M KCl (pH 2.7) was determined as 29,000 by measuring S0 and D0, 25,400 by calculating from s0 and [η], and 25,000 by the sedimentation-equilibrium method. The size of PC at pH 2.7 is likely a half of 1/4-1/ 5 size subunit, in which 2 moles of PC is possibly linked through one -S-S- bond.

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The role of -SH group of beef liver catalase was studied, especially in respect to the kinetic constants in the reactions of the propyl hydrogen peroxide (PrOOH)­ complex compound I formation and decomposition. Masking of 6 -SH groups per mole, that was titrated in the native state with PCM B, by S-carbamylmethylation did not affect the initial rate of catalatic H2O2 decomposition and the rate of the compound I formation, but it reduced the reaction rates of the compound I towards electron donor (ethanol) and of spontaneous decomposition. An accelerated inactivation of the masked catalase by H2O2 is discussed in terms of the inactive compound II formation as a result of reduced reactivity of the compound I with substrate in a catalatic or peroxidatic way.

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In experiments on benzene poisoning various species of animals are used, and the susceptibility to benzene differs from species to species. The special qualities of experimental animals must be well characterized in order to compare experimental results and to plan future experiments. Four species of animals (rabbits, hamsters, rats, and mice) were used in the present experiment. Benzene in an olive oil mixture was injected subcutaneously into the backs of the animals for five successive days. The animals were sacrified on the sixth day of the experiment. By measuring body weight, hemoglobin content, erythrocyte count, leucocyte count, spleen weight, and thymus weight of all experimental animals, the difference in susceptibility to benzene was shown obviously. 1) In mice, a marked drop in weight of spleen and thymus, and a considerable decrease in hemoglobin content were observed. In rats, body weight, weight of spleen and thymus, and leucocyte count decreased markedly, and thrombocytosis was observed. Male hamsters usually showed decrease in thymus and body weight and thrombocytosis. Rabbits showed a great decrease in weight of spleen and thymus, and a marked leucopenia and drop in body weight. 2) Rats were the most susceptible to benzene; hamsters, the least. 3) Difference in susceptibility to benzene was observed between male and female animals. Male hamsters and male mice were more susceptible than females, but on the other hand, female rats and female rabbits were more susceptible than males.

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The purpose of this study was to observe the influence of loss of the lower teeth on the weight of the mandible. The materials used in this experiment consisted of sixty-seven mongrel dogs, which were extracted on lower right posterior teeth with the exception of control animals, and which were classified according to their age, sex, number of extracted teeth and time after extraction of teeth. Two halves of their mandibles were weighed separated from each other, and the right half, namely the operated side was set against the left, the control side to estimate the changes of the mandible in weight following extraction of the lower teeth. The following results were obtained: The weight of the mandible extracted on lower posterior teeth decreases in growing animals, and appears to be diminished in the mature, although it increases transiently. There is a distinct difference in the change of the weight between the growing dog and the mature, and that is, the former has an intenser change than the later. But there is no significant difference between the male and the female, and also between the animals extracted on all lower posterior teeth and those extracted on the lower first molar. The weight of the mandible in the growing decreases significantly in six months after the loss of the teeth, but subsequently ceases to change. In the mature animal it remains unchanged in three months afte1 the extraction of the teeth, then increases significantly in the period between third month and twelfth, and decreases distinctly afterwards.

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A method is described for the extraction and determination of pontamine blue exuded in the skin of rabbits, in order to measure increased vascular permeability to protein. It involves four procedures, viz., (1) homogenization of the skin treated with hot trichloroacetic acid solution, (2) precipitation of gelatinized collagen with phosphotungstic acid, (3) lipid extraction with ethanol and (4) elution of the dye adsorbed to protein with aqueous pyridine and its spectrophotometric determination. Its successful application to the skin response, induced by histamine, indicates that the method can be used for the quantitative study of substances that affect vascular permeability.

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Gingival fluid is a very common clinical symptom of the periodontal disease. But its nature has not been fully understood. To obtain further knowledge concerning its function and biochemical characteristics, flow of gingival fluid and lactic acid in gingival fluid were quantitatively determined. Though relatively large deviation was observed, flow of fluid tended to increase with the enhancement of gingival inflammation. Lactic acid from clinically normal gingiva could not be determined quantitatively in most cases. But when gingival inflammation existed, lactic acid was demonstrated in all cases and tended to increase with gingival inflammation. The correlation between flow of fluid and lactic acid content was significant. But highest lactic acid concentration was observed in the gingival fluid from mildly inflamed gingiva. Lactic acid content in gingival tissue and its concentration of blood serum were also obtained. It was found that lactic acid concentration of blood serum influenced neither to that of gingival fluid nor to lactic acid content in gingival tissue. But statistically significant correlation was observed between lactic acid concentration in gingival fluid and its content in gingival tissue. It must be concluded that gngival fluid should be inflammatory exudate and the analysis on gingival fluid has a clinical diagnostic value.

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