4-Nitroquinoline-N-oxide was demonstrated to possess a very powerful carcinogenic action. Applied to the skin of normal mice three times a week this substance in 0.25 percent benzene solution produced papillomata in all the animals during the period between 80th to 140th day, and malignant tumors between 120th to 200th day. At 150th day, 100 percent of the mice bore tumors and in 36 percent the tumors were already malignant. The malignant tumors produced were histologically squamous cell carcinoma or fibrosarcoma. Metastases were found in a few cases. These tumors were found to show the glycolytic activity in vitro consistent with their malignant nature. One of the tumors was successfully transplanted to normal mice.
4-Nitroquinoline-N-oxide is the first bicyclic compound to be shown to have the carcinogenic activity of the magnitude approaching that of the most potent polycyclic hydrocarbons.

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1. Sarcoma was produced at the site by repeatedly injecting 0.2-1.0gdl solution in propylene glycol of p-quinone subcutaneously into normal rats.
2. The use of propylene glycol alone resulted in no tumors during a 88 week course of the injections.
3. No notable change in internal organs was found in the rats in these experiments.

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1. p-Hydroxypropiophenone administered orally to a group of seventeen rats fed with 0.06% DAB diet for 160 days exhibited a 100% inhibition of incidence of hepatoma and of cirrhosis.
2. Imperfect hypophysectomy in a group of ten rats appeared to have some inhibiting action in a similar series.
3. The above findings were compared with those in the control group administered with DAB alone.
4. PHP appeared not definitely acting via hormonal system, in view of histological findings of the organs of the animals.
5. Some data are presented to suggest the possibility of a direct action of PHP to the hepatic cells in inhibiting the liver damage and carcinogenesis, although the mechanism involved leaves much to be investigated in the future.

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Radioactive iron was injected into control and tumor-bearing rats. The tumor used was Rhodamine sarcoma, which is relatively free from necrosis and hemorrrhage. The iron amount and radioactivity were determined in tumor, plasma, hemoglobin, liver, kidney and spleen 24 hours after the injection.
The concentration of iron in liver and plasma decreased in tumor-bearing animals. The incorporation of radioactive iron into hemoglobin increased and the incorporation of radioactive iron into liver decreased in tumor-bearing animals. It was estimated that the total iron contained in tumor-tissue was larger than the total iron amount in liver.
Distribution of iron in tumor-bearing animals was discussed in relation to anemia, liver catalase depression and porphyrin acummulation in liver and red cells in the case of tumor-bearing animals.

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Pigeon breast muscle succinoxidase purified by repeated isoelectric precipitation, could not reduce TTC in the presence of succinate even though the excess amount of boiled extract of liver or crude coenzyme A as cofactor was added. And TTC reducing activity was restored by the addition of dialyzed supernatant of rat liver homogenate.
It was concluded that a certain protein component, which is contained in rat liver supernatant and has no succinic dehydrogenase activity by itself, was required for TTC reduction by succinoxidase with cofactor.
Rat liver particles could not efficiently reduce TTC in the presence of succinate, but the addition of boiled supernatant and dialyzed supernatant could restore the TTC reducing activity. The addition of each one, per se, could not restore the activity.
The system for the determination of cofactor activity was suggested because the amount of boiled extract or crude coenzyme A became a rate limiting factor under the addition of the excess amount of dialyzed rat liver supernatant.
Rat liver homogenate could reduce TTC in the presence of reduced cytochrome c. In this case, also, the cofactor and protein component were required for efficient TTC reduction by rat liver particles.
Methylene blue could enhance the TTC reduction in rat liver homogenate by succinate. Cyanide strongly inhibited TTC reduction in rat liver homogenate by succinate, but inhibited it less in the addition of methylene blue.
From these results, the mechanism of TTC reduction by succinoxidase were discussed.

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A new preparation method of the polar dye from defatted liver powder of rats fed DAB for a month has been described. The absorption spectra of the most purified sample of the polar dye up to date have been shown, which have absorption maximum at 514 to 517mμ, 270 to 280mμ and sometimes slight shoulder at 310 to 320mμ in acid media. The absorption maximum was observed at 400mμ and 280mμ in alkaline media. The data accumulated so far seem to make aminoazobenzene-tyrosine binding the most probable model of the polar dye.

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[in Japanese]

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[in Japanese]

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[in Japanese]

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The authors have computed the standardised death rates of some selected countries, with the relevant data for 1951-1954 kindly furnished us by the central statistics offices of the countries as basis and with the sex and age distribution of the Japanese population as standard, and using these standardised death rates, made a geographical observation on the mortality from cancer of all sites, and of stomach, esophagus, lung, breast, uterus, ovary, and prostate.

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