eR BitSatara Aue sig Hieam ee RADIATION INJURY! TPR PATHOGENESIS AND THERAPY 21h The anemia develops slowly, results from. a partial or cotuplete cessation of blood formation. from hemorrhage and pethape from increased blood destruction (Lawrence, Dowdy and Valentine: Cronkite, 1948, Young . In the animats that ultimately die, a severe cachexia is usually appatent before death. The extensive necrosis, uleeratiun, and edema of the bowel which is apparently secondary to the paneytopenia and extensive hemorrhage into the bowel, may contribute significantly to malnutrition. Asa general rule, animals that cease to eat, particularly the mouse, dic within 48 hours. The food intake and weight of all animals decreases in the first few days after irradiation, the survivurs regain some of their weight and may not have a secondary drop. Those animals which fatl to start eating again or who have a secondary occurrence of anorexia lose weight rapidly and die (Chapman and Cronkite; Suuth ef al). Radiation death is not the result of simple starvation, however, as evidenced by the fact that obese mice die at the expected time (Smith, Chapman, and Alderman). 9.7 Factors Modifying the Response to Whole Body Irradiation Various factors may favorably or unfavorably influence the lethality of total-bedy exposure to ionizing radiation or the sensitivity of various structures to ionizing radiation (see also Chapter 12). These factors may conveniently be grouped into preirradiation and postirradiation factors, Before taking up those factors which are specifically proved to modify or not to modify the response, the following generalities have been assumed true by most, though not necessarily proved. 9.7.1 Age and Ser. The very young appearto be more sensitive to radintion (Abrams, Kohn and WNallman). Some evidencefor increased sensitivity of children wax seen in the exposed Marshallese (Cronkite ef a/.). There seems to be little dependence of sensitivity on age in the mature animal (sohn and Wallman); however, the rat shows increasing sensitivity with increasing age. There is evidence that the female may be moreresistant than the male (Cronkite et al.; Carter ef al.); however, the difference is small and is not found consistently, particularly with small populations. 9.7.2 Enetronment. There is some evidence that cold, trauma, hunger, muscular exertion, and noise will increase the lethality of a given dose of radiation. Since a major cause of death following potentially lethal irradiation is infection, it is not unreasonable to expect that anything that would inerease the susceptibility to infection would increase the mortality. 9.7.3 Allergy, Immunity, Metabolic Disorders, and Dictary Deficiencies. Thereis little known about the influence of these factors on the survival of man. However, mice with induced hyperthyroidism are more sensitive (Blount and Smith). Dietary deficiencies of vitamins and proteins generally seemto increase the incidence of radiation illness after x-ray therapy, par- 5012879 ¢