The purpose of this report is to describe a new method of evaluating therapeutic activity in shock and to present evidence for a principle in liver extract, which has the activity of significantly decreasing the mortality which follows a standardized scalding burn.The development of new therapeutic agents useful in shock has, in large part, been impaired by the absence of standardized quantitative methods for evaluating anti-shock activity. During the past 2 years, a shock-producing procedure has been developed in this laboratory that has permitted satisfactory evaluation of antishock activity in the shock which occurs following a scalding burn. The A., 1943, 122, 720. tained to be statistically evaluated for their significance. A similar scalding method has recently been described (1).
METHODThe water-bath used in these experiments was a 10 gallon jug, in which the water was mixed by a stirring motor. The bath temperature was regulated by a thermostat so that it varied no more than 4:0.5' C. After the bath had been set at the desired temperature, rats or mice were rapidly anesthetized with ether. The loose skin in the occipital region was then grasped with a hemostat, and the animal was plunged into the scalding water in such a manner that only the head and neck remained above water. After the desired interval of immersion, the animal was withdrawn and placed in a bucket containing sawdust to permit partial drying. The rate of traumatizing animals by this scalding procedure may be increased several-fold if animals are anesthetized in groups and 2 or more animals are simultaneously scalded. Using these procedures, 2 people may scald as many as 6 rats or mice every minute. The duration of exposure to the scalding temperature was generally 10 to 15 seconds. The accuracy of these immersion periods was approximately 40.5 second. These intervals of exposure appeared to be optimal, since decrease in duration to 5 seconds decreased the accuracy of the exposure, while with the immersion periods above 20 seconds it was observed that animals tended to awaken from anesthesia and began to struggle. Ether anesthesia was used in preference to non-volatile anesthetics, such as avertin and nembutal, for the reason that we have found that avertinized and nembutalized animals which had been scalded awakened from anesthesia very slowly. Following the start of the experiment, food and water were withheld from the animals.Survival observations after thermal injury were conducted over a 48-hour period, and all experiments were terminated at that time to prevent the effects of infection and other secondary disturbances, which later become operative, from influencing mortality. The groups were observed at regular intervals, the dead animals being removed and the time of death noted. A small percentage of the animals died within the first 30-minute period following scalding and these animals were discarded from the experimental groups because it seemed unlikely that death was due to secondary shock. All animals still alive when th...