 499  Once the system has arrived at the correct frequency, the AFC loop can be opened or the r—f signal can be removed without changing the oscillator frequency. 188. In Table II are recorded, together with the observations on coplement titers and antigen clearance, the incidence of the two major lesions found in hypersensitivity of the serum sickness type. Since in the present experiment observations were made only at 8,12 and 16 hours after injection of immune precipitates, the prompt reduction in hemolytic complement titers following BGG precipitates was not encountered and no difference in the complement titers was observed in the two groups of animals. 189. To build the transmitter, first collect three pieces of cardboard tubing each about 12 inches long. The two larger pieces should be about 1 '/2 inches, respectively, in diameter so that the smaller one will telescope snugly into the larger one. The third piece of tubing should be about 5/8 inch in diameter so it can accommodate a flashlight bulb. The diameters of the two larger tubes are not too important althougt the largest should be big enough to talk into comfortably. 190. Transferable pyrogen was readily detected in the serum of leucopenic rabbits with endotoxin fever, provided a sufficient volume of serum was used in the passive transfer test. The febrile responses of normal recipients to intravenous injections of 25 ml aliquots are shown in Fig. 1. It will be noted that the resulting fever curves exhibit the relatively short latent period, the peak within 60 minutes, and the rapid defervescence characteristic of the febrile reaction to both leucocytic and serum endogenous pyrogen. 191. The LD50 for mice of a series of endotoxin preparations containing different amounts of bound lipid appear in Table I. These findings, which present a more extensive series of data than we have reported previously, make it evident that lipid content does not bear any relationship to toxicity, as measured by lethality for mice. All preparations were potent and the distribution of LD50 values was about what would be expected in the same number of replicante determinations on the preparation with an average LD50 of 0.25 mg. 192. Reincubation with fresh enzyme resulted in the liberation of only small additional amounts of ether-extractable mate-rial. It is possible that the products formed inhibited the sulfa-tase. This point requires further investigation. 499 |
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