Application of gamma-ray spectrometry with a Ge (Li) detector and then instrumental neutron activation analysis to tissue samples from a Thorotrast patient using the same standard reference sample makes it possible to determine both232Th concentrations and activity ratios of the descendant nuclides to232Th in living tissues. This analytical method is nondestructive, being simpler and more reliable than the methods previously used. In the present study, the activity ratio of228Ra/232Th in living tissue was estimated at 0.37 to 0.44, being somewhat lower than the value reported by Kato. As for the activity ratio of228Th/228Ra, our value agreed fairly well with Kato's value. A stomach sample from a Thorotrast patient was found to contain the same level of232Th as liver and spleen samples; trace amount of232Th was also found in kidney and brain samples.
222Rn Determination method by liquid scintillation counter after extracting222Rn with p-xylene was studied. It was confirmed that extraction of222Rn with p-xylene proceeds quantitatively. Several experimental conditions for the counting such as scintillator content in pxylene, the quencher effect, the zero level extrapolation method and 3-channel counting method were examined. The recommended procedures were successfully applied to measure222Rn content in one of the natural water. It was noticed that we should pay attention to220Rn (Tn) which is simultaneously extracted with 222Rn in case of p-xylene extraction.
Incorporation of uracil and orotic acid into the ribonucleic acid (RNA) fraction of rat liver during carcinogenesis induced with 3'-methyl-4- (dimethylamino) azobenzene was investigated. Uracil incorporation was found to be gradually elevated during the early stage (about 2 weeks) of the carcinogenesis, although not in the normal rat liver homogenates contacted with the carcinogen for a short hours, and the elevated uptake was maintained until tumor induction. On the other hand, orotic acid incorporation reverted to the original level after a temporary increase during the early stage. In a good agreement with the increased uracil incorporation, activities of both uridine phosphorylase and uridine kinase involved in the salvage pathway of RNA synthesis also increased during the early stage, and their activities in the liver were maintained at elevated levels after discontinuance of the carcinogen feeding. The activity of uridine monophosphate (UMP) pyrophosphorylase, converting uracil to UMP, was not detected during the early stage. Significance of the activation of the salvage pathway of RNA synthesis during the early stage of an azo dye-induced carcinogenesis were discussed.
In order to know if it is possible to objectively decide the extent of infiltration of female genital malignant tumors into parametrium by using111In-bleomycin scintigraphy, a fundamental and clinical investigation was made. The result was as follows; 1) The radiochemical purity and stability of111In-BLM were comparatively unchangeable. When this complex was kept at room temperature for a week, there was not more than 2% of the free111In. 2) As to blood clearance, when the blood radioactivity of111In-BLM 5 minutes after the injection was counted as 100%, about 80% of the radioactivity was cleared from the blood in 48 hours. Over 50% of the radioactivity was excreted into the urine in 48 hours. 3) Of 29 cases of female genital malignant tumors, 23 cases (79%) showed positive images. Therefore111In-BLM was found to be one of the suitable radiopharmaceuticals for the diagnosis of female genital malignant tumors. 4) 111In-BLM scintigraphy was of great use for deciding the extent of the invasion of carcinoma cervicis uteri into parametrium and for the search of metastasis.
Attempts were made to attain a semiquantitative evaluation of therapeutic effectiveness of lung cancer by scintiscoring of the liver as well as the tumor lesion. A relative counting ratio of tumor to liver was computed, and this was found useful: in areas of active tumorous growth, higher ratios were obtained. The ratios returned to the control levels following irradiation with or without an anti-inflammatory regimen including prednine. The technic is simple, and yet invaluable especially when the tumor locates in the mediastinum escaping from radiological detection. Satisfactorily frequent repetition would be competent enough in early diagnosis of developing radiation Pneumo-mediastinitis and regrowths in the mediastinum and fibrotic abnormal shadows as well. The principle would be best rewarded by use of a wholebody scanner equipped with a digital computer.