THE ABSCOPAL EFFECT OF X IRRADIATION ON BONE GROWTH IN RATS
The abscopal effect of irradiation (that which is evident at a distance from the irradiated volume but within the same organism) was investigated in rats. It was possible to demonstrate the effects on growth locally and abscopally when x-ray doses of 400 and 800 r were delivered to the lower extremity and when 800 r was delivered to the knee alone. A distinction between abscopal effects after local irradiation and systemic effects after whole-body irradiation is discussed. The weights of control and irradiated animals were similar for the first 21 days, during which period they did not exhibit any untoward effects of irradiation. However, after 21 days there was a decrease in weight gain, which persisted until the 72nd day. Group A (controls) was the heaviest group, with a mean weight of 412 g. Group B (800 r to the left hind extremity) had a mean weight of 378. Group C (400 r to the left hind extremity) and Group D (800 r to the left knee) exhibited mean weights of 391 and 394 g, respectively. Roentgenographic measurements revealed that all animals receiving irradiation had retardation in the growth of the irradiated tibiae, which were shorter than both the control and the contralateral (unirradiated) tibiae. Only the animals that had received 800 r to their leff hind extremity showed significant differences in the lengths of their unirradiated bones compared with the bones of the control animals of Group A, that is, a significant abscopal growth retardation. Although the abscopal effect appeared to be associated with the volume of tissue irradiated, the way this effect is mediated is not known. The weight gains of the animals demonstrated a strong association between decrease in weight gain, the volume of tissue irradiated, and the dose administered. The impaired weight gsin roughly paralleled the abscopal retardation of bone growth. The animals which received the highest dose of irradiation, 800 r, to the largest volume of tissue, 10% of the body volume, revealed the greatest deviation from the control group. It is concluded that irradiation effects in animals are composites of the responses of the whole organism to the injury, of the responses of local tissues, and vessels at their level of tissue organization, and of the responses of individual cells. All of these responses may be interdependent. The evidence indicates that a systemic inhibition of all bone growth and weight gain occurs when a sufficient volume of tissue is irradiated at a sufficiently high dosage. (BBB)
- Research Organization:
- Children's Hospital Medical Center, Boston, Mass.
- NSA Number:
- NSA-18-000077
- OSTI ID:
- 4177536
- Journal Information:
- J. Bone Joint Surg., Vol. Vol: 45A; Other Information: Orig. Receipt Date: 31-DEC-64
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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