TOCP (Tri-orthocresyl phosphate), an organophosphorus compound, has been implicated in producing neuropathy in the male S. D. rats. Repeated subcutaneous doses of TOCP (600 mg/kg) for up to 6 weeks produced ataxia, most striking at 50 days after final injection, followed by gradual recovery. Ultrastructurally, the internal structure of affected nerve fibers was primarily composed of altered smooth endoplasmic reticulum, tubular membrane system, and mitochondria, although myelin sheath was found to be essentially normal. In the histopathological examination, axonal and myelin degeneration was disclosed in the gracile nucleus and in the gracile fasciculus of the cords as well as in the sciatic nerves. The localization and degree of these changes were considered to be "dying back", showing systemic neuropathy. In addition, muscular lesion showed small group atrophy, corresponding to Type I fiber atrophy.

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Groups of 21 male and 21 female mice were given diets containing 20%, 10%, 1% or 0%(control) perlite for 28 weeks. Appearance, behavior, mortality, and food consumption of mice of treated groups were not affected during the experimental period. Males of the 20% and 10% groups did experience slightly reduced growth rate. No significant drug-related changes were found in urinalysis, hematology, serum chemistry, and organ weight. No differences were found between control and treated groups in autopsy and histopathological findings. Therefore, the maximum no-effect level is considered to be 1% in the diet which developed no toxic changes in any items examined in mice treated orally with perlite for 28 weeks.

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Effects of oxygen and superoxide anion to mutation rate were examined using the method of Ames. As test samples, 3-methylcholanthrene or 3, 4-benzpyrene dissolved in squalene was used. In order to increase the concentration of dissolved oxygen in the medium during preincubation, oxygen was bubbled into the medium. Various combinations of xanthine oxidase, superoxide dismutase and hypoxanthine were used with an intent of changing the concentration of superoxide anion in the medium during the preincubation. An increase in the concentration of dissolved oxygen and superoxide anion resulted in a lower mutation rate, clearly showing the relationships of mutation rate with oxygen and with superoxide anion.

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Syrian golden hamsters were administered 8-nitroquinoline, at a concentration of 0.05%, in a 10% ethanol solution as drinking water for 104 weeks. The animals were kept under observation until 112 weeks of age when the experiment was terminated. Both control and treated groups developed tumors in a pattern indistinguishable from that usually observed in Syrian golden hamsters. Thus the result of this experiment indicates that 8-nitroquinoline given orally at a concentration of 0.05% is not carcinogenic in Syrian golden hamsters.

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The chronic toxicity of a new topical glucocorticoid, difluprednate (DFBA) was studied in Beagle dogs. DFBA ointment (0.05%) was percutaneously treated to the back of dogs at daily doses of 125, 12.5 and l.25 μg/kg for 6 months. 1. The local effects of DFBA; In the treated area, thinning of the skin and inhibition of the fur-growth were observed with scale and erythema. The skin showed histological atrophy of the epidermis, a decrease of the adipose tissue and atrophy of the adnexa. These changes returned to normal after the 2-month withdrawal period. 2. The systemic effects of DFBA; (1) In the 125μg/kg group, the following changes were observed, although neither death nor severe symptoms occurred: a) General observations were seen an increase of water intake and urinary volume. b) A decrease of lymphocytes and eosinophils, and an increase of neutrophils were observed in the hematological examination. c) There were high sodium and low potassium levels, and an increase of alkaline phosphatase and γ-glutamyltranspeptidase activities in the biochemical examination. d) The organ weights showed a decrease of the thymus, adrenals, prostate and ovaries, and an increase of the liver and kidney. e) An atrophy of the lymphatic tissues and adrenal cortex, retardation of the sexual maturation, glycogen deposit in the hepatic cells, slight degeneration of the renal tubuli, and slight thinning of the sternum and non-treated skin were noted in the pathological examination. These changes returned to normal after the 2-month withdrawal period. (2) In the 12.5μg/kg group, the atrophic changes in the thymus, adrenal and non-treated skin appeared slight. (3) In the 1.25μg/kg group, no changes were found. 3. Conclusively, all the local and systemic changes observed by DFBA in this study were due to the already known pharmacological effects of glucocorticoids. It is considered that a 12.5μg/kg dosage is similar to a non-effect dose.

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The mutagenicity of ST-film and its components polyoxyethylenenonylether (NP-10) and polyvinylalcohol (PVAL) were studied by a reverse mutation test in S. typhimurium (Ames test), a chromosome test in cultured Chinese hamster V 79 cells and a micronucleus test in female mice. The results obtained from these test systems were all negative. Thus, it may be concluded that ST-film is not mutagenic either in vitro or in vivo mutagenicity testing systems.

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Fertile eggs were injected 10 or 20 mg/egg of aminoguanidine sulfate (AGS) into the albumen on the 5th day of incubation and examined macroscopically and histopathologically. The marked abnormalities were observed in liver, gallbladder and spleen while other organs were not different from the control. The earliest change was an increase of mitotic cells in the liver which reached to the peak at 2 days after the AGS injection. The increase of the ratio of cells in metaphase was characteristic. Decrease of weight, retardation of the development, fatty degeneration, necrosis and increase of connective tissues in the liver were followed. The abnormality of gallbladder such as aplasia and hypoplasia was observed with high frequency. Spleens of the AGS-treated group were enlarged from the 16th day of incubation. The clearest change of spleen was fatty degeneration.

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The antigenicity of difluprednate, phototoxicity and photocontact sensitivity of difluprednate ointment and cream were studied in guinea pigs and mice. The results in this study were as follows. 1) Guinea pigs immunized with difluprednate emulsified with freund's complete adjuvant did not exhibit the systemic anaphylaxis and the delayed type hypersensitivity by the elicitation with either difluprednate alone or difluprednate-BSA conjugate. The antisera obtained from these guinea pigs did not show the positive response in the homologous 4-hour PCA reaction and the passive hemagglutination test against the challenge of the same antigens described above. 2) In the maximization test, guinea pigs immunized with difluprednate did not show the contact sensitivity when elicited with difluprednate suspended in saline. 3) Guinea pigs applied difluprednate ointment did not show positive contact sensitivity by the elicitation with difluprednate ointment and ointment base. 4) The antisera obtained from mice immunized with difluprednate and difluprednate-OVA conjugate absorbed to Al (OH)₃ gel did not give the positive response in the 72-hour PCA reaction against the challenge of either difluprednate alone or difluprednate-BSA conjugate. 5) In the phototoxicity and photocontact sensitivity test, 0.05% difluprednate ointment and 0.05% difluprednate cream did not show positive reactions in guinea pigs, although very slight erythema was caused by the primary irritancy of cream base, with or without irradiation of ultraviolet ray (320-400nm).

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