Biology and Medicine
UNCLASSIFIED
Activities of the Brookhaven National Laboratory
Experiments to determine the relative biological effectiveness
of fast neutrons in producing acute lethality in mice.
A number of
investigators have performed experiments to determine the relative bio-
logical effectiveness (RBE) of fast neutrons in producing acute lethality
in mice.
Conflicting values have been reported, ranging from 1.5 to
5.0 RBE. An investigation to throw more light on these discrepant
results has recently been completed. Measurements have been made of the
doses of X rays and neutrons required to produce a lethal effect of
50 percent in 30 days (iD 50/30) in female mice.
Two hundred and fifty
kvp (kilovolts peak) X rays were used.
The fast neutron irradiations
were performed with fission neutrons produced in the Brookhaven reactor.
Tissue equivalent lonization chambers were employed to measure the
neutron dose.
The X rays LD 50/30 dose was determined to be 636 rads,
and the neutron dose 366 rads, giving an RBE of 1.7. This confirms the
low RBE values obtained by other investigators at the Oak Ridge, Los
Alamos, and Naval Radiological Defense Laboratories and indicates that
there is no difference between cyclotron-pulsed neutrons and continuously
produced neutrons from a reactor in producing a lethal dose of 50 percent.
Prevention of thrombocytopenic purpura produced by whole-body
radiation.
Thrombocytopenic purpura (a decrease of blood platelets to
below normal levels) produced by whole-body irradiation can be prevented
by transfusion of fresh platelets.
In recent experiments, the survival,
distribution, and fate of platelets transfused into the irradiated
thrombopenic rat were studied using radiosulfur-labeled platelets. A
potential mechanism of the role of platelets in the prevention of
hemorrhage has been demonstrated in that the radiosulfur-labeled material
from the platelet or the intact platelet itself appears to have been
selectively incorporated into the capillary lining. Whether this means
that platelets contribute some sulfur-rich macromolecular substance that
is essential to prevent vessel breakdown, or that they play a more
secondary role by initiating fibrin formation at a submicroscopic level
is a matter for additional investigation.
Cobalt 60 source installed. A 500-curie cobalt 60 source was
supplied from Brookhaven National Laboratory to the Bland Experimental
Farm, University of Virginia, on July 15.
This irradiation source will
be used for the irradiation of plants and seeds.
Studies in Treatment of Irradiation Injury - Oak Ridge National Laboratory
Mammalian recovery studies.
Lethally irradiated mice receiving
massive and multiple injections of homologous or heterologous bone marrow
showed the same delayed death pattern as the controls that received
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UNCLASSIFIED