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RADIATION INJURY: ITs PATHOGENESIS AND THLEAPY
2L
posed to large doses of radiation in the Japanese bombings and in reaetor
accidents and similar observations on huge ardinials diving frou; radiiton
exposure, (b) Correlative stuclics ot mortality rate, time of death. and imeldence of positive blood cultures in aninuds. (e) Challenge of irradhived
animals with virulent and normally nonvirulent organisms. (d) Studies on
germ-free animals, (e) Studies of the effectiveness of antibioties im reducing
radiation mortality rate. (f) Studies on the effectiveness of agents that will
augment or restore natural antimicrobial defenses on mortality rate im irradiated animals. A brief word on each of these lines of evidence is given
below.
Vhe Japanese dying of ‘atombombendisense’ and human beings heavily
exposed at the Los Alamos accident (Hempleman «f al.) and Yugoslav
{Mathé ef al.) showed unmistakable evidence of infection. Signs and
symptoms included high fever, Ludwig's angina and other mucosal and
cutaneous infections, cellulitis, pneumonia and septicemia. Autopsy
findings bore out the clinical picture. Similarly with large animals, particularly dogs, the temperature begins to rise 3 to 4+ days before death,
and is usually quite high prior to death. Orocutaneous lesions are common,
At autopsy, pneumonia is the rule, as well as other evidence of infection.
At doses of total body radiation even in the high sublethal range, however, (Marshallese expoxed to fallout gamma radiation, Cronkite et al.) no
evidence of increased susceptibility to infection may be manifest. The
Marshallese, in some of whom the neutrophile counts fell below 1000 per
mm.*, showed no increase in the incidence of infectious diseases over control
groups. Epidemics of upper respiratory infection, measles and ehicken pox,
that occurred were no more pronounced in extent or severity in the exposed
population compared to unexposed Marshallese in whomsimilar epidemics
occurred at the same time. Similarly, the heavily-exposed individuals in
the Y-12 accident (Andrews ef al.) showed no infections that could be
attributed definitely to radiation exposure.
The time of peak incidence of bacteremia in irradiated animals has been
correlated with the time of peak incidence of mortality in the extensive
studies of C. P. Miller and his group. The organisms are chiefly enteric in
origin, and apparently gain access to the blood stream through the bowel
wall. A pusitive correlation, of course, does not prove cause and effect, and
it has been stated that such organisms represent agonal invasion and thus
maybe “incidental.” A cause andeffect relationship seems highly probable,
particularly in the hight of evidence from antibiotic therapy studies outlined below. Total bodyirradiation has been shown to activate infections
that otherwise remained “latent” (Bond ef al.).
Challenge of irradiated animals with virulent, or normally nonvirulent
bacilli results in death at infective levels that produce no mortality in nonie
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