. Basic mechanisms in radiobiology. 89 may be complicated by rapid removal of some pyknotic cells. This is particular- ly evident in the blood stream, as shown by Trowell (4). BARRON: How many hours after irradiation can you get lymphopenia? PATT: Within a few hours after irradiation. Maximal spleen involution or involution of lymph nodes occurs within a day or two after 100 r to the whole body. DUBOIS: The endogenous respiration of either the spleenor thymus gland decreases markedly in one day after exposures to 400 r. It may decrease a little more in the following 3 to 5 days. There is then
. Basic mechanisms in radiobiology. 89 may be complicated by rapid removal of some pyknotic cells. This is particular- ly evident in the blood stream, as shown by Trowell (4). BARRON: How many hours after irradiation can you get lymphopenia? PATT: Within a few hours after irradiation. Maximal spleen involution or involution of lymph nodes occurs within a day or two after 100 r to the whole body. DUBOIS: The endogenous respiration of either the spleenor thymus gland decreases markedly in one day after exposures to 400 r. It may decrease a little more in the following 3 to 5 days. There is then a gradual return so that at 1 4 and Zl days the rate of endogenous respiration again approaches the normal value. This is a reversible inhibition of endogenous respiration and correlates quite well in time with the reversibility of the functional activity of these tissues after 400 r. BARRON: You have not measured the respiration in terms of DNA? DUBOIS: No. PATT: The curve for endogenous respiration resembles very nicely the curve for spleen involution. With 400 r, the peak would appear at about 3 days, with recovery becoming apparent during the next several days. DUBOIS: In connection with these ob- servations on the respiration of tissues of irradiated animals, I feel that it is not prof- itable to study the oxidative phase of carbo- hydrate metabolism in the liver, kidney, heart, and brain, but that there is a great deal to do in connection with radiosensitive tissues like spleen and thymus. Studies of ' the overall metabolic activity of tissue slices may be considered as preliminary to more definitive 12 Z? W" HOURS AFTER 800 R OF X-RAY Figure 1. Effect of 800 r of X radiation on the accumulation of citric acid in tissues of fluoroacetate-treated rats. (This chart was published in a paper by , Cochranand J. DouU in Proc. Soc. Exp. Biol, and Med. 76, 422-427 1951). To obtain further information on the gross effects of irradiation on the oxi
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