Late effects in the XXXX small intestine after a clinically relevant multifractionated radiation treatment.

@entity82 @entity548 @entity19 @entity4 @entity1017 @entity1188 @entity1321 @entity130
Late radiation effects were investigated in the @entity19 small intestine after a daily fractionated radiation treatment. @entity19 were given 14 X 3 Gy in 2 weeks over a partial abdominal irradiation field. There was evidence for late injury in the intestinal epithelium, the submucosa, and the subserosa. Late damage in the epithelium was shown histologically by a reduced crypt number and villus atrophy at 3 and 6 months but not at 24 h after the end of treatment. The reduction in crypt number was significant in the ileum at 3 and 6 months after irradiation: 100 +/- 4 and 98 +/- 5 (SEM) per circumference, respectively, versus 132 +/- 3 and 146 +/- 6 in age-matched controls (P less than 0.01, t test). The mitotic activity in the crypts of the irradiated animals was significantly increased at all investigated times, suggesting a prolonged but insufficient compensatory response to maintain the mucosal integrity. The repercussion on intestinal epithelial function was, at least in part, reflected by a progressively reduced body @entity1017 up to 5 g at 3 months after treatment. The ability of the surviving crypt stem cells to form microcolonies after irradiation, however, was not impaired. Evidence for @entity130 was provided from macroscopic and histological examination. Macroscopically, at 6 months after treatment, narrowed and rigid bowel segments surrounded by fibrotic adhesions were observed, causing partial @entity1321 . In addition, sometimes focal areas of @entity548 and @entity1188 in small bowel segments were present. Histologically, diffuse and pronounced @entity4 without increased @entity82 was seen, together with markedly dilated small blood vessels in focal areas of macroscopic @entity1188 . The intestinal perfusion, as assessed by 86Rb extraction, was significantly but transiently reduced at 3 months after irradiation. These data suggest mainly late effects in the small intestine after this daily fractionated irradiation treatment. The reduced number of epithelial cells and the @entity4 are possibly mediated by radiation injury in the intestinal microvasculature.
