Acute Intestinal Death Research Articles

Higher sensitivity of LEC strain rat in radiation-induced acute intestinal death.

LEC strain rats (LEC rats), which have been known to develop hereditarily spontaneous fulminant hepatitis 4-5 months after birth, were highly sensitive to whole-body X-irradiation as compared to WKAH strain rats (WKAH rats). Radiation-induced acute intestinal death occurred at doses higher than 6.5 Gy in LEC rats, and at doses higher than 12.8 Gy in WKAH rats, respectively. By the probit analysis of survival data, it was shown that the LD50/7 value of LEC rats was estimated to be 7.03 Gy which was significantly lower than that (12.99 Gy) of WKAH rats. Histopathological examinations of small intestines from LEC rats 2 days after irradiation at the dose of 8.5 Gy showed severe epithelial death together with edema, whereas little or no significant changes were noted in intestinal epithelium of 8.5 Gy-irradiated WKAH rats. These results suggest that the radiosensitivity of LEC rats to ionizing radiation appears to be higher than that of other strains of rats.

High energy fast neutrons from the Harwell variable energy cyclotron. II. Biologic studies in mammalian systems

A high energy fast neutron beam potentially suitable for radiotherapy has been described in a companion paper. Its biologic effects have been studied in the following experimental systems: clonal survival and mutation induction after irradiation in vitro in Chinese hamster cells and human diploid fibroblasts; survival of reproductive capacity in vivo of murine hemopoietic colony-forming cells and murine intestinal crypts after irradiation in vivo; survival of reproductive capacity in vivo after irradiation in vitro or in vivo of murine lymphocytic leukemia cells; acute intestinal death following total body irradiation of mice and guinea pigs; and hemopoietic death following total body irradiation of mice and guinea pigs. The relative biologic effectiveness of these high energy neutrons varied among the different biologic systems, and in several cases varied with the size of the radiation dose. The oxygen enhancement ratio was studied in murine lymphocytic leukemia cells irradiated under aerobic or hypoxic conditions in vitro and assayed for survival of reproductive capacity in vivo. Compared with x-rays, the potential therapeutic gain factor for these neutrons was about 1.5. This work represents a ''radiobiologic calibration'' program which it is suggested should be undertaken before new and unknown fast neutron spectra are used for experimentalmore » radiotherapy. The results are compared with biologic studies carried out at high energy fast neutron generators in the United States.« less

Radioprotective effect of some pyrazolone derivatives

Analgin, antipyrine, and aminopyrine, if administered to mice in large doses 3 h before irradiation (800 R), increased the survival rate and prolonged the life of the dying animals. In combination with cystamine, these compounds increased the changes of survival of the mice after the period of acute intestinal death following irradiation in a dose of 1050 R. In therapeutic doses the pyrazolone derivatives had a less marked radioprotective effect.

Course of the post-irradiation syndrome after irradiation with lethal doses in newborn conventional, germ-free and Escherichia coli-monoassociated piglets.

The influence of whole-body irradiation with lethal doses of ionizing radiation (60Co) was studied in conventional, germ-free andEscherichia coli-monoassociated newborn piglets. The dose 1,200 R produced an acute intestinal death (i.e. within 3–4 days) in conventional animals, whereas survival was three times as long in their germ-free counterparts. Artificial colonization of the intestinal tract of germ-free piglets with non-pathogenic strain ofEscherichia coli, prior to irradiation with the same dose, produced the conventionalization of these animals and reduction in the survival time almost to the level of conventional animals. In conventional animals, profound focal regressive changes of the epithelium accompanying the denudation of intestinal villi were found already on the 2nd–3rd day after irradiation with 1,200 R. On the other hand, the intestinal epithelium of germ-free piglets, irradiated with 1,200 R, was found to be intact on the 7th–9th day of post-irradiation, and the first signs of damage started to occur around the 9–10th days. The morphological characteristics of the intestinal mucous membrane ofEscherichia coli-monoassociated piglets were comparable to those of conventional, irradiated piglets. The role of the presence of the microbial factor for the turnover and radiosensitivity-resistance of enterocytes, and for the survival-death rate of animals irradiated with doses producing the post-irradiation gastro-intestinal syndrome, is discussed.

Protection through parabiosis against the lethal effects of exposure to large doses of x-rays.

Parabiotic rat pairs with a skin-vascular anastomosis were used to test whether shielding of one member of the pair would protect the irradiated partner against exposure to very large doses of x-rays (1200 to 2400 roentgens). Except with the lowest dose, all unshielded, irradiated pairs or single irradiated animals died before 5 days had elapsed. In contrast, irradiated rats that had a shielded parabiont partner survived the 5-day period and many survived beyond 30 days. This is interpreted as protection against the acute intestinal death that normally occurs in the dose range investigated.

Effects of Whole-Body Irradiation on the Transfer Capacity of Rat Small Intestine

It is now well established that X-irradiation of the whole animal produces damage to the intestine. Indeed the resulting from large doses of irradiation is probably due to the intestinal damage and has been called acute intestinal death by Quastler (1). The characteristic pathology is the denudation of the intestinal lining, so it is scarcely surprising that irradiation produces serious interference with absorption. The effect on absorption has been studied by many workers, and recently well reviewed (2), but the interesting question which still remains unsettled is how far damage to specific functions can occur in irradiated animals as distinct from general damage to the cells. In the present paper the problem has been approached by studying different transport functions in the intestine, and comparing the extent to which changes in these are related to metabolic and histological changes in the gut. As the object is to demonstrate functional changes, nonlethal doses of irradiation were used, and the functional capacity was observed at varying times after irradiation.

Whole-Body Irradiation in the Young Pig: Growth, Hematology, and Metabolism of Calcium-45 and Strontium-89

Numerous experiments have been conducted to study the effect of whole-body X-irradiation on the rat and mouse. Growth rate is depressed in rats during the first 10 to 14 days after exposure to sublethal irradiation, and this depression is associated with a reduction in feed intake (1, 2). The small intestinal segment of the gastrointestinal tract appears to be extremely sensitive to whole-body irradiation. Sublethal doses have been shown to decrease glucose and thiamine absorption (3, 4), whereas Ca45 and Sr5 absorption is increased (5, 6). These levels of irradiation cause transitory changes in the gastrointestinal epithelium which recover by 5 to 7 days. Supralethal doses (1000 r or higher) produce acute intestinal death within 3 to 5 days probably because of the loss of water and electrolytes through the small intestine from which the epithelium has been denuded (7). The present series of experiments were undertaken to study the effect of whole-body ionizing irradiation on the growth, feed intake, hematology, and metabolism of Ca45 and Sr89 in the young growing pig. METHODS

Observations on Gastrointestinal Function after X-Ray and Thermal Column Exposures: I. Effect on the Progress of Barium Meal, Body Weight, and Survival

Disturbances in function have long been recognized as outstanding sequelae of exposure of animals to ionizing radiation. It was noted by early investigators (1, 2) that the abdomen was the most radiosensitive body region and that doses tolerated by other anatomic areas led to systemic intoxication and early when delivered to the abdomen. It was later demonstrated by Quastler et al. (3) that occurring in mice 3 to 4 days after whole-body X-irradiation was associated with a direct effect of radiation on the intestine, and that an acute intestinal death resulted from doses of 1200 to 10,000 r. Langham et al. (4) reported a similar time of for rats over the same dose range and a 3to 4-day in monkeys after doses of 1200 to 5000 r. To date relatively little is known about the relationship of dose to specific dysfunctions and the consequent pathophysiologic events which lead to death. Anorexia, nausea, and vomiting are well-recognized manifestations of dysfunction after radiation exposure, but by themselves they are probably not lethal in 3 to 4 days. Water and electrolyte losses from copious diarrhea have been suggested repeatedly as probable causes of the gastrointestinal death, but there have been no quantitative determinations of the rates of these losses, their duration, or their relationships to dose delivered or time of death. The