Ilo M. Alderman

Sensitivity of irradiated mice to bacterial endotoxin.

Summary Exposure to radiation, especially in the lethal range, caused a marked increase in sensitivity of mice to S. typhosa endotoxin. This was most pronounced on the third day after irradiation. At that time the endotoxin LD50 in mice given 1000 rads was 0.5 μg compared to a control value of 480 μg per 20 g mouse. Shielding the hind legs was without effect on endotoxin LD50 (2.3 μg for 850 r, 200 KV X-rays). Shielding the back, including the adrenals, was partially effective (LD50, 55 μg). Treatment with cortisone had an effect comparable to that of shielding the back. Shielding the front of the animal, including practically all of the intestinal tract, was very effective in spite of the fact that the adrenals were irradiated (LD50, 410 μg). Shielding a small portion of the abdomen was also quite effective in reducing endotoxin sensitivity in the irradiated mice (LD50, 165 μg).

Effect of pretreatment with colchicine or a colchicine derivative on hemopoiesis in irradiated mice.

Treatment of mice with colchicine or trimethylcolchicine acid methyl ether prior to irradiation caused an increase in bone marrow cellularity which was apparent 3 days after LD5 irradiation; no significant increase in granulocyte counts 3 to 4 days after irradiation; a relatively small but significant increase in lymphocyte counts 3 to 4 days after irradintion; an advance in the time of recovery of granulocyte counts consistent with the effect on survival, which was equivalent to a mean dose-reduction of 180 rads; and a similar advance in the time of recovery of lymphocyte counts.

Radiation Dose-Response Characteristics of Leucocytes in the Mouse

Summary 1. In mice, changes in dose in the sublethal range could be detected by means of lymphocyte counts 2 to 4 days after irradiation with an estimated accuracy of 66 rads, but as the dose was increased it soon became impossible to distinguish between doses by means of lymphocyte counts. 2. Changes in dose in the range 0 to LD95 could be detected by granulocyte counts 3 days after irradiation with an estimated accuracy of 145 rads and 4 days after irradiation, 107 rads. 3. Prior injection of endotoxin did not improve the accuracy of dose discrimination 3 days after irradiation. Four days after irradiation accuracy was increased in the higher dose range but usefulness of the procedure was limited by the acutely toxic effect of the endotoxin on lethally irradiated mice.

Radiation Dose-Response Characteristics of Leucocyte Recovery in the Mouse

Summary Dose-response characteristics of recovery times of granulocyte and lymphocyte counts to 1500 cells per cu mm in peripheral blood have been described for irradiated mice. The dose corresponding to a given time of recovery could be estimated with reasonable accuracy for granulocytes over the dose range 275–770 rads and for lymphocytes over the range 450–770 rads. For granulocytes recovery time increased 42% and for lymphocytes 30% per 100 rad dose increment. Together with earlier studies of 3- and 4-day counts, dose-response characteristics of recovery times are useful in distinguishing between dose-reducing effects and effects relating specifically to recovery processes.