Shunzo Okajima

ESR Dosimetry for Atomic Bomb Survivors Using Shell Buttons and Tooth Enamel

Atomic bomb radiation doses to humans at Nagasaki and Hiroshima are investigated by electron spin resonance (ESR) from shell buttons and tooth enamel voluntarily supplied by survivors. A shell button gives a dose of 2.1±0.2 Gy with ESR signals at g=2.001 and g=1.997 while the signal at g=1.997 for the tooth enamel of the same person is 1.9±0.5 Gy. Other teeth show doses from about 0.5 Gy to 3 Gy. An apparent shielding converted to a concrete thickness is given using the T65D calculated in 1965. Teeth extracted during dental treatment should be preserved for cumulative radiation dosimetry.

Mortality of registered A-bomb survivors in Nagasaki, Japan, 1970-1984.

A follow-up study of A-bomb survivors registered in Nagasaki was conducted from 1970 to 1984 by the Scientific Data Center of A-Bomb Disaster at Nagasaki University, which has collected medical and administrative data on A-bomb survivors with the help of Nagasaki City Hall and other organizations. The purpose of this study was to investigate the following two points. (1) Has the health screening program for A-bomb survivors reduced the mortality rate? (2) If so, how much has it reduced it, and what would the life-shortening effect of radiation be without the health screening program? The results revealed that the effect of radiation on mortality would be underestimated if the health screening factor were ignored. The estimated effect of radiation dose was compared with that estimated by the Radiation Effects Research Foundation (RERF).

Measurement of 239Pu in soil and plants in the Nishiyama district of Nagasaki

Nishiyama district in Nagasaki is located approximately 3000 m east of the hypocenter of the atomic bomb that was dropped on 9 August 1945. This district is also known as an area where there was a concentrated radioactive fallout with the black rain that was carried by a westerly wind. The Nagasaki atomic bomb was a Pu bomb, and the fallout must have included 239Pu without fission in addition to fission products. The presence of 239Pu in Nishiyama district has been confirmed previously. In this study, the distribution of 239 + 240Pu concentration in the uncultivated soil and the transfer factor of 239 + 240Pu to agricultural products in Nishiyama district were examined. The concentration of 239 + 240Pu in the uncultivated soil was 20 Bq kg-1, which was approximately eight times as high as that in the control districts. The transfer factor of 239 + 240Pu to agricultural products was 10(-4) - 10(-3), which was 1/100-1/200 of that of 137Cs.

Changes with age in swimming performance of X-irradiated mice

Abstract The time required to swim 250 cm was determined once weekly for the entire life of fifteen pairs of male dd/K mice. The irradiated group was exposed to a single 224 rad of X-rays at 20 weeks of age. Median survival time (ST50) for the control was 88.9 weeks and that for the irradiated group was 77.4 weeks, and both regression lines relating to death rate and age were parallel. The swimming ability of control mice began to decrease when the mice were 40 weeks of age, after which there was a gradual reduction with age, at 0.00646/day. In the irradiated group, the swimming ability decreased from seven weeks after the irradiation. The time of 50% reduction of swimming speed (TRS50) for the control was 78.9 weeks and that for the irradiated group was 66.3 weeks, and the slopes of the regression lines relating reduction rate and age were similar. Differences between ST50 and TRS50 were 10 weeks in the control and 11 weeks in the irradiated group, respectively. These results indicate that there is no basic difference in the reduction in swimming ability between control and irradiated mice. The X-irradiation may simply mean that the reduction in the swimming ability is displaced to an earlier time, with no alteration in the rate of reduction, and that the earlier appearance in the irradiated group is related to premature aging as induced by irradiation.

Necessity of Glycolysis for Recovery from Ultraviolet Killing of Saccharomyces cerevisiae

respiratory rate of diploid yeast: Survival was consistently high in cells grown in anaerobic complete medium where only glycolysis was operating, while it was low in cells grown in aerobic glycerin medium where only oxidative phosphorylation was operating; these observations are consistent with the observed shift from the high resistance in logarithmic phase to the lesser resistance in stationary phase in cells grown in aerobic complete medium. Immediate recovery, which was determined by the ratio between split-dose survival and no recovery survival, occurred only in cells having a low respiratory rate and not in cells having a high respiratory rate. Severe suppression of aerobic ATP synthesis during the first hour after irradiation was found only in cells having a high respiratory rate. Otherwise, delayed recovery, which was determined by immediate plating on glycerin medium, was not related to the respiratory rate. These results indicate a low resistance to uv of oxidative phosphorylation in mitochondria existing at the time of irradiation and a high resistance to uv of both glycolysis and oxidative phosphorylation in new mitochondria produced after irradiation. Survival therefore may be dependent on whether irradiated cells can recover from sublethal damage by utilizing ATP produced by glycolysis immediately after irradiation.

Effects of X Irradiation on Respiratory Control and P/O Ratio in Isolated Rat Liver Mitochondria Having Different Respiratory Control Ratios

The respiratory control and P/O ratios of isolated rat liver mitochondria held aerobically in buffered 0.3 M mannitol-0.2 mM EDTA in an ice bath decreased exponentially immediately after X-irradiation at 20,000 R, in close correlation with the decrease of the preirradiation respiratory control. Of the two indicators of mitochondrial intactness, the respiratory control was the more sensitive to irradiation. This radiation effect appeared to be similar to uncoupling. The losses of respiratory control and P/O ratio in the irradiated mitochondria were amplified by transfer to ice-cold buffered 0.15 M mannitol without EDTA; the degree of this amplification reached a maximum for values of the preirradiation respiratory control ratio in the neighborhood of 4.0. The nature and direct cause of the radiation damage in mitochondria are discussed.

Early morphological changes in the cortical and medullary thymocytes of the rat after whole-body irradiation. II. Quantitative investigation.

The increased irregularity of rat thymocyte nuclei observed by electron microscopy after whole-body x-irradiation with 1000 R was assessed quantitatively by the use of the I value, the ratio of the perimeter to the area of the nucleus. The mean I values for both cortical and medullary thymocytes registered an increase 1 hr after irradiation. The value for medullary thymocytes decreased at 3 hr, while it remained unchanged for cortical thymocytes. Furthermore, a decrease in number of normal cortical and medullary thymocytes as a function of time after irradiation with 1000 R was observed by electron microscopy. Analysis of the relationship between the increased nuclear irregularity and pyknosis led us to confirm quantitatively the previous findings of the present authors that this increase in irregularity is the process preceding pyknosis.

Sensitivity to ultraviolet light of RNA synthesis under different culture conditions in Pseudomonas effusa.

Comparative studies were made on the sensitivity of the synthesis of individual ribonucleic acids (RNA) components to ultraviolet light (UV) under conditions that (A) suppressed ribosomal RNA (rRNA) synthesis and permitted preferential synthesis of messenger RNA (mRNA); (B) permitted balanced synthesis of individual RNA components; and (C) suppressed mRNA synthesis and permitted preferential synthesis of rRNA. Under condition A, mRNA synthesis was found to be much more UV-sensitive in the presence than in the absence of inducer. Under condition B, no preferential inhibition of the synthesis was observed for any one of the mRNA peaks. Synthesis of rRNA was more readily found to be UV-sensitive with the increasing molecular weight of RNA under condition C than under condition B.

Modification of the effect of ultra-violet irradiation by a nutritive condition on RNA-synthesis during the induction of catechol oxygenase in Pseudomonas effusa

Summary(1) The effect of ultra-violet irradiation on the synthesis of RNA was very different according to nutritive conditions of Pseudomonas effusa.(2) There was significant damage to the synthesis of mRNA, dependent on the inducer, under both the deficient and the enriched conditions by u.v.-irradiation with a dose sufficient to block the induced synthesis of catechol oxygenase.(3) u.v.-irradiation under the enriched condition had an inhibitory effect on the synthesis of rRNA.