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- BIOLOGY AND MEDICINE
to the prevention or reversal of toxic actions on living organisms. Data derived from thesestudiesare examined to establish maximum permissible levels of exposure for man and -
laboratory ‘animals and to provide a basis for the prediction of biological damage in cells * ;
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and tissuesafter a given exposure. Such studies are important not only for rec pgnition andey a
evaluationof radiation damage but also for the development of.therapeutic and fliagnostic
applications in the treatment of diseased cells and tissues. Only a few examplds of these
investigations can be reported here.
Effects of X Rays on Frog Retina
The University of California Radiation Laboratory, Berkeley, has
1
complet#d a study of the effect of X rays onanimal retina, particularly the retinal response of bull
frogs to:
small doses of X rays to determine adaptation and recovery. It was found that B electrical.
response could be measured on the retinaafter an exposure of as little as 0.6
oentgens,::
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that during exposure to X rays the sensitivity to light was reduced, and that th¢ retina 8 “
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recovered less rapidly after X ray stimulus than after light stimulus. The recbveryof
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the retina to penetrating: radiations indicates that the effect is to alarge«exten! reversible: be oo us
Biological Eifectsof Radiation
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Los Alamos ‘Scientific ‘Laboratoryhas been experimenting to determine
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’ effects in miceof whole body X radiation. Pretreatment of mice ‘with p-amino bropio- 2
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phenone (an agent producing @ pronounced deficiency: in oxygen) or glutathione exertedate.
marked protective effect against, whole body X radiation. Buta negligible degwee of pro- 2°
tection was found when mice 80 pretreated were exposedto radiation from the thermal
.-: _
‘ column of a reactor (thermal neutrons plus.gamma contaminant). Thus, it appparsthat“.
agents which are protective against one type of ionizingtradiationmay not be df value
againstall types.
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Radiation Effects on Mortality
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The effects of whole body irradiation of male rats on‘mortalityamong theiir offepring | :
is being studied by an AEC-University of Tennessee research group. Male rais were roa exposed to 300 roentgens of gamma rays from a cobalt 60 source, or to X rayp froma . .
250 kilovolt machine. The irradiated males were mated to virgin females. Tie pregnant
females were sacrificed, and it was found that the fetal death rate showed an
Increase in
comparison with nonirradiated control rats. The fetal mortality rate for the Jarious
groups was: control group, 6,46 per cent; gamma-ray exposure, 19.37 per cet; and
X rays (250 kv), 19.92 per cent.
After 60 days the same male animals were used in repeating the breeding
test. The
values obtained after sacrifice of the second group of pregnant females were 7.39 per cent
for gamma exposure and 8.19 per cent for X rays. The decrease in fetal momality rate |
between the first test and: the second test of the irradiated males indicates t at there is a
period of recovery, and that the initial high mortality rate may be due to don inant lethal
mutations induced during exposure in the more mature testis cells.
For several years research has been proceeding on the role of the spledn as a pro- ,
tective organ in preventing radiation injury. Recent work at Argonne Nationd@l Laboratory
has indicated that a considerable degree of protection is provided against su%sequent
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Prevention of Tumors’ Following Irradiation
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development of lymphoid tumors when the spleens of mice are shielded durigg irradiation.
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