All issues
Volume 13, Issue 4
Displaying 1-7 of 7 articles from this issue
- |<
- <
- 1
- >
- >|
-
A. MURAKAMI, M. MIKI1972 Volume 13 Issue 4 Pages 183-192
Published: December 01, 1972
Released on J-STAGE: August 29, 2006
JOURNAL FREE ACCESSThe changes in radiosensitivity during embryogenesis of the silkworm, Bombyx mori L. were investigated. The radiosensitivity expressed as LD50(R) values was estimated from the dose-hatchability curves obtained following irradiation with X-rays and 137Cs gamma-rays.
Data obtained in the present study together with results previously reported indicated that the radiosensitivity generally decreased as the embryonic development proceeded and that the age-dependent change in radiosensitivity may strongly depend on the degree of morphogenesis. From the viewpoint of the marked differential stage sensitivity, the process of embryogenesis may be divided into two main phases : one is a sensitive phase which corresponds to the time prior to and during blastokinesis (or before the completion of the embryonic morphogenesis) and the other is an extremely resistant phase which corresponds to the stage after blastokinesis. The former embryo was about 10 times as high in radiosensitivity as the latter embryo. The implication of these results was discussed.View full abstractDownload PDF (478K) -
Y. ENOMOTO, K. WATARI, R. ICHIKAWA1972 Volume 13 Issue 4 Pages 193-198
Published: December 01, 1972
Released on J-STAGE: August 29, 2006
JOURNAL FREE ACCESSThe whole body retention of three chemical species of 106Ru was studied in rats. Three ruthenium species were ruthenium chloro complex (Ru-chloro), nitrosyl ruthenium nitrato complex (RuNO-nitrato) and nitrosyl ruthenium nitro complex (RuNO-nitro).
When the compounds were administered orally, RuNO-nitro complex showed the highest retention, while RuNO-nitrato and Ru-chloro complexes demonstrated a comparablly low retention. The cumulative urinary excretion for three days of RuNO-nitro complex was the highest. The excretion of RuNO-nitrato was slightly but significantly higher than that of Ru-chloro complex.
When the compounds were injected intravenously, the whole body retention of Ru-chloro complex was the highest, followed by RuNO-nitrato and RuNO-nitro in this order.
These results suggest (1) that RuNO-nitro complex was absorbed more readily through gastrointestinal wall to the body than RuNO-nitrato and Ru-chloro and (2) that RuNO-nitro and -nitrato complexes in the body were metabolized and excreted faster than Ru-chloro complex.View full abstractDownload PDF (252K) -
Y. SUZUKI, R. NAKAMURA, T. UEDA1972 Volume 13 Issue 4 Pages 199-207
Published: December 01, 1972
Released on J-STAGE: August 29, 2006
JOURNAL FREE ACCESSThe 90Sr contents in bones of freshwater fishes (carp and gibel) from radioactive fallouts were investigated in relation to those in the surrounding waters from 1963 to 1970. The specific activities (90Sr/Sr) of fish bones and of the surrounding waters declined rapidly from 1963 to 1964, followed by a gradual decline from 1964 to 1970. The specific activities of fish bones were always slightly higher than those of the waters, except that of gibel in 1963. The time lag between Sr specific activities of fiish bones and those of surrounding waters were 270 days for carp and 360 days for gibel.
The discrimination between stable Sr and Ca in freshwater fishes was demonstrated : In the field studies, the Sr-Ca observed ratio (OR) were determined as 0.74±0.05 for carp and 0.84±0.07 for gibel respectively. In rearing experiments, the Sr accumulation of carp reared in the water of 2×10-1 mg Ca/l was twice as much as that in water of 2×102 mg Ca/l.
It is now possible to estimate 90Sr content in the bones of carp and gibel by using their OR values and the time lag of Sr specific activity between the freshwater fish bone and the surrounding water.View full abstractDownload PDF (295K) -
A. SHIRAGAI1972 Volume 13 Issue 4 Pages 208-213
Published: December 01, 1972
Released on J-STAGE: August 29, 2006
JOURNAL FREE ACCESSThe absorbed doses in a cell nucleus from β-particles emitted by incorporated tritium atoms in the nucleus are estimated on the basis of energy dissipation algorithm as follows ; the energy dissipated at depth t by a beam containing one electron/cm2 may be represented as d(ηE)/dt, where η is the probability of transmission and E the residual energy.
The absorbed doses which were calculated with constant absorption model in the previous work are found to agree well with the present results. It is known that the results which are obtained by using the average energy of 3H β-particles are appreciably different from the ones based on the β-spectrum.
Furthermore the calculated results are compared with the other estimation methods and the conclusions deduced from these models are briefly explained.View full abstractDownload PDF (225K) -
T. KOBAYASHI, K. MATSUMOTO, G. YOSHII1972 Volume 13 Issue 4 Pages 214-220
Published: December 01, 1972
Released on J-STAGE: August 29, 2006
JOURNAL FREE ACCESSIsolated silkgland ribosomes were irradiated with X-rays, and their activities to synthesize fibroin in vitro were examined. A marked decrease in their activities was observed when ribosomes were incubated at 37°C following X-irradiation. Per cent decrease in the ribosomal activity leveled off at 37°C after 30 minutes incubation. The extent of decrease was dependent on X-ray dose. Treatment of ribosomes with pancreatic ribonuclease showed a decrease in the ribosomal activity. These results suggest that a type of radiation damages on irradiated ribosomes is likely to be revealed during the post-irradiation incubation period through a possible interaction with ribonuclease either activated or released by X-irradiations.View full abstractDownload PDF (291K) -
S. ROKUSHIKA, F. MURAKAMI, T. SENDA, H. HATANO1972 Volume 13 Issue 4 Pages 221-229
Published: December 01, 1972
Released on J-STAGE: August 29, 2006
JOURNAL FREE ACCESSRibonuclease A were gamma-irradiated in a dilute aqueous solution. The G° value of inactivation of the enzyme was 0.45. When the enzyme lost its enzymatic activity significantly, some physicochemical or chemical properties were found to be altered, while others were not. Unaltered properties were ‘type’ of amino acid terminals, optimum pH and pH-enzyme activity curves. Properties affected by irradiation were a destruction of some amino acid residues, an alteration of electrophoretic mobility, and an incresed reactivity to diazo-1-H-tetrazole. The extents of alteration of the latter two properties were dependent upon the radiation dose. These results suggest that the ionizing radiations induce a local conformational change in the enzyme molecule and that this may play an important role in the inactivation of the enzymatic activity of ribonuclease A.View full abstractDownload PDF (373K) -
S. MURAMATSU1972 Volume 13 Issue 4 Pages 230-233
Published: December 01, 1972
Released on J-STAGE: August 29, 2006
JOURNAL FREE ACCESSVirgin female mice, CF#1 strain, were continuously irradiated with 60Co gamma rays at a dose-rate of 6 R/day from conception to natural death. A marked life shortening was found for the irradiated group. The mean life span of irradiated group was 384±25 days (the mean accumulated dose being 2307.7 R), while that of the non-irradiated control group was 642±12 days.View full abstractDownload PDF (151K)
- |<
- <
- 1
- >
- >|