982 RADIATION BIOLOGY 



few hours or days of life. Little can be said about the efficiency of the 

 circulation to specific sites or the capacity of the cardiovascular system 

 to compensate for any excessive demands, such as repeated transfusions 

 of whole blood or plasma, that may be placed upon it. These considera- 

 tions deserve attention, for they pose a number of practical problems, 

 especially in the event of combined radiation and traumatic injuries. 



GASTROINTESTINAL TRACT 



Many of the manifestations of irradiation of the whole body are refer- 

 able to the gastrointestinal tract, which constitutes a sensitive locus for 

 radiation action. The nausea, vomiting, and anorexia of clinical radia- 

 tion sickness were first described by Walsh in 1897, and degeneration of 

 the intestinal mucosa of irradiated animals was reported by Krause and 

 Ziegler in 1906. Perhaps the most significant of the early observations 

 were those by Regaud, Nogier, and Lacassagne in 1912 and by Whipple 

 and his associates in 1919-1923. Regaud et al. (1912) pointed out that 

 the small intestine of the dog is more sensitive to direct X irradiation than 

 the stomach or colon and that the duodenum and jejunum are the most 

 sensitive regions of it. Hall and Whipple (1919) and Stafford L. Warren 

 and Whipple (1922a, b, c, d; 1923 a, b, c, d) described a toxic reaction 

 following heavy irradiation of the abdomen, which was most marked at 

 the time of greatest injury to the crypt epithelium and resembled intoxica- 

 tion resulting from intestinal obstruction or severe nonspecific intestinal 

 injury. The effects of X irradiation of the abdomen were also shown to 

 be more severe than those following exposure of other portions of the 

 body. Similar conclusions may be drawn from more recent investiga- 

 tions (Moon et al, 1940; Friedman, 1942; Shields Warren and Friedman, 

 1942; Bond et al, 1950; Quastler et al, 1951). 



Early extensive gastrointestinal injury followed by death within 

 several days is seen after massive dosages of radiation delivered either 

 to the abdomen or to the whole body (Hall and Whipple, 1919; Moon 

 et al, 1941; Quastler et al, 1951). Intestinal injury is generally con- 

 sidered to account for the toxicity resulting from such exposure. It has 

 been found, for example, that the mean survival time in mice over the 

 dose range of 1000 to 12,000 r is three to four days and that early killing 

 occurs only if a large portion of the intestine is irradiated (Quastler et al, 

 1951). Exposure of the liver, kidney, spleen, and adrenal does not lead 

 to early death, at least in mice. This picture is probably different from 

 that observed after lower dosages, where several competing mechanisms 

 contribute to the lethal action. By exposing only the lower abdomen of 

 mice, thus irradiating a considerable portion of the small intestine while 

 sparing the liver and spleen, Chrom (1935) observed a reduction in the 

 enterogenous infection and greatly reduced toxicity with dosages of 



