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The response of man and animals to whole-body irradiation is of major interest. Due to obvious experimental difficulties, observations of large animals have been limited in comparison to those on small laboratory species. Tullis et al. (1) have reported lethal dose investigations with swine, and Prosser et al. (2) mention a lethal dose study with goats but give no details. Some data are also becoming available from various field experiments performed in conjunction with atomic bomb tests (3, 4). So far as is known, there have been reported no other similar studies with animals having a tissue mass or body volume approaching that of man. There is little or no information dealing with such interrelated problems as significance of depth dosage, time-intensity relationships, gamma rays vs. x-rays, radiosensitivity of various species, extrapolation from small to large animals, and sublethal physiological effects. The burro (Equus asinus asinus) was chosen for initial whole-body irradiation investigations becau...

Summary and Conclusions1. Nine burros exposed to a lethal dose of whole body gamma radiation were observed. The burros had symptoms and pathologic changes characteristic of the irradiation syndrome. Four died during the first week and the remaining 5 died before the 30th post irradiation day. These 5 showed hemorrhagic symptoms. 2. There was a retardation of whole blood clotting time. A clotting defect was demonstrated in recalcified oxalated plasmas of burros tested 2 weeks after irradiation. 3. All irradiated burros developed a severe thrombocytopenia and a lessening of clot retraction was noted on the after 4th post irradiation day, with no clot retraction after the 16th day when the platelet count was approaching zero. 4. There was a pronounced diminution of prothrombin utilization rate after irradiation. The first change was noted 22 hours after irradiation or 3 hours after the animals were removed from the exposure field. 5. There was no demonstrable circulating anticoagulant. The possible relation ...

SummaryA study has been made of the response of the burro to 200 r fractional Co60 gamma ray whole body irradiation. The response is similar to but slower than that observed with a daily dose of 400 r. The response of the platelets to irradiation with 200 r daily corresponded most closely with that seen when an acute LD50 dose had been given and correlated with the bleeding tendency which developed on the ninth irradiation day. A significant hyperferremia was observed in the burro one hour after receiving a total dose of 600 r but the maximum response was not obtained until 1800 r had been administered. Most animals had significantly elevated plasma iron values prior to exitus.

SummaryRabbit pituitaries from animals exposed to 750 and 1100 r of total body Cobalt-60 gamma irradiation showed an early suppression of gonadotropin principles as measured by the chick gonad response. The 750 r group showed the depression on the 8th day after irradiation while in the 1100 r group the suppression was evident by day one and was sustained through day 7. After this time the gonadotropin activity in both groups returned to the normal level.

In 1954 it was shown that nuclear weapons tests had produced radioactive materials (primarily iodine-131) that were accumulated and detectable in the thyroid glands of livestock in the United States (I). Further survey values for both man and animals have been presented in U.S. Atomic Energy Commission reports and in the open literature (2-4). The magnitude and pattern with time of radioactivity levels in the thyroids are of interest because (i) there is provided an alert to any build-up of potentially hazardous levels; (ii) as relationships are developed, radioiodinc measurements could serve as a sensitive monitoring system for other fallout nuelides less easili detected in the hiosphere; (iii) information may be obtained on the movement of radioiodine particularly in the biological system; and (iv) there could be an interference with medical diagnostic tests that employ low levels of radioiodine. This paper (5) summarizes the information that has been obtained on the levels of iodine-13 1 in human and cattle thyroids and presents an estimate of milk levels in the United States during the period from January 1955 to December 1956. Correlation with known bomb tests is noted, and some inferences are drawn about routes of exponire.

A LD 50/30 value of 651 r was previously reported for the burro exposed to whole-body tantalum-182 irradiation (1). Comparison of that value with those in the literature was impractical because of the species difference and variations in the conditions of exposure. This paper presents the LD 50/30 for burros and swine exposed under similar conditions except that cobalt-60 was used as the source of radiation instead of tantalum-182. These data, together with some physical factors, will be discussed in terms of lethal response as a function of species and of various physical factors. Method The method of selection of the burros was described in previous reports. Forty males and 10 females, two and a half to three and a half years old, weighing from 115 to 164 kg., were selected. All were in good health. For five groups of 10 burros each the mean exposures were 605, 690, 750, 790, and 945 r (Table I) (1). For this study the exposure field was activated with cobalt-60 instead of tantalum-182 (2). About 37 cur...

The LD50(30) for burros irradiated at a rate of 15 r/hr with gamma radiation from Zr95/Nb95 sources was 585 r with a 95% confidence interval of 530 to 627 r. The mode of death was characterized by an absence of early deaths and occasional prolonged survival time beyond 30 days, of lethally irradiated animals. A variable I131 uptake by thyroid, decreased iron uptake, increased blood pyruvic acid and pancytopenia were measured in circulating blood of irradiated animals. The lethality of gamma irradiation from Zr95/Nb95 was greater than that of gamma radiations fronm Co60 or Ta182 if the free-in-air doses were compared. The midline doses necessary to produce the same biological effects were about equal, however, for the various sources when all factors were considered.

Radioactivity in Manis essentially a report of a symposium held at Vanderbilt University School of Medicine, April 18-19, 1960. It contains the papers and discussions of eminently competent participants. A wide spectrum of interests is covered, including biomedical, biophysical, physical, legal, and sociological aspects of man and ionizing radiation. However, little factual information that has not been documented by the same experts elsewhere is included. The book contains an excellent explanation of the gamma ray scintillation spectroscope, models of dosimetry, illustrations of the hardware, and the use and limitations of whole body counting of internal radionuclides by gamma ray spectroscopy. Examples of the use and interpretation of results of whole body counting following nuclear reactor accidents and exposure to atomic fallout are given. The research potential of the counting methods are discussed. The callibration of and total body count by large crystal scintillation counters and the 4 π liquid

It may be assumed that radiation injury is composed of at least two components, one of which is irreparable. It may be assumed further that the irreparable injury may be measured by its additive effect on subsequent exposure to ionizing radiations, and that after a postirradiation period of 90 days all the injury remaining is irreparable except for an insignificant amount of slowly reparable components. With these assumptions this experiment was planned to measure directly the injurious effect of sublethal doses of -y-radiation in terms of life shortening. The life span of all the experimental animals was to be shortened by a daily exposure of

A group of 10 male burros was exposed to a total of 350 r weekly in six daily doses of 58.3 r of cobalt-60 y-radiation until death. These will be identified by the term "50 r/day." A second group of 10 male burrows was exposed to 25 r daily until death. The exposure rate was 48 r/hr. The exposure device and dosimetry have been previously described (4). Hemoglobins were determined colorimetrically by the method of Dupray as modified by Wong and Hanzel (5-7). Platelet counts were made by the BrecherCronkite method (8), and the remainder of the hematologic values were obtained by methods described by Wintrobe (9). Plasma irons were determined by the method of Kitzes et al. (10). Electrocardiographic records were made with a Sanborn cardette, model 70, with an attached universal lead selector. The total hay and water consumption of all the animals was recorded daily.

Thyroids of burros and rats studied at this laboratory increased their storage of '131 after irradiation with lethal and sublethal levels of -y-rays to the whole body. This led to an investigation of the 02 consumption, the C02 production, and the calculated respiratory quotient of the irradiated burro which is herein reported. An increase in metabolic activity or oxygen consumption after irradiation has been reported (1-3) for rats and dogs. No change in 02 consumption was noted by others in rats (4), mice (5), or guinea pigs (6). Three species of small animals show considerable difference in weight response after irradiation (7) which seem to indicate a difference in their metabolic activity. In mice a reduced CO2 production, to 80'% of normal, had been reported (8). These varied results in small animals led to the present study of the respiratory exchange in the chronically irradiated burro, in conjunction with other observations made at the time.