Tolerance of Gaspe fishermen to cold water

A group of Gaspé fishermen used to cold water immersion and control subjects from the same vicinity were studied to determine if the fishermen's hands were adapted to cold. With one hand immersed in cold water, the pressor response was greater in the control subjects; the fishermen maintained a higher finger temperature and complained less of pain; heat flow from the fishermen's hands was greater than in the control group; finger numbness as measured by a modification of Mackworth's V-test was variable and not significantly different in the two groups. Skin biopsies showed no difference in skin thickness or cell size but there was a significantly greater number of mast cells in the fishermen's skin. The differences between the fishermen and the control subjects may be related to repeated cold exposure.

Submitted on June 7, 1960

Heat output in the cold from hands of Arctic fishermen

The heat output from the hands of Arctic fishermen was studied by water calorimetry, using an initial water-bath temperature of 4°C. The fishermen were compared with a group of young men not habituated to work in the cold. The subjects were investigated when comfortably warm and when kept in heat debt by being chilled. The total heat output from the hand during the 30 minutes of calorimetry ranged from 1907 cal/100 ml hand tissue/min. (cold room) to 4886 cal/100 ml hand tissue (warm room). There was found no significant difference of the mean heat output between the two groups, neither when they were in general heat balance, nor when in heat debt. One subject who developed cold urticaria showed a considerably higher heat output than any of the other persons investigated. The results do not agree with the view that men habituated to working in the cold with their hands show an increased blood flow in the cold when studied under environmental temperatures low enough to produce a general vasoconstriction.

Submitted on March 21, 1960

FEVER PRODUCED BY MICROINJECTION OF TYPHOID VACCINE INTO HYPOTHALAMUS OF CATS

In unanesthetized cats, 1 or 2.5 µliters typhoid vaccine were injected into several areas of the hypothalamus, the lateral cerebral ventricle, and other areas of the brain. The concentrations of the pyrogen used ranged from 1/8 to 1/16,000 of the dose required to produce fever by the intravenous route. Fever was obtained in all experiments in which the vaccine was applied to the anterior hypothalamus or to the lateral cerebral ventricle. No significant rise in temperature occurred following injections into other brain areas unless extremely high doses were employed. The short latency and the rapid rise in temperature following the injection of typhoid vaccine into the anterior hypothalamus suggest that pyrogens act on the cells of this diencephalic structure when fever is produced.

QUANTITATIVE STUDIES OF THE ANTAGONISM BY NALORPHINE OF SOME OF THE ACTIONS OF MORPHINE-LIKE ANALGESIC DRUGS

A quantitative investigation has been made of the antagonism by nalorphine of the analgesia and lenticular opacity produced in mice by a number of compounds. ED50 values have been obtained for each drug in the absence and in the presence of increasing doses of nalorphine, and from these, appropriate dose-ratios have been calculated. It has been possible to derive the equivalent of a pA(2) value for each drug with nalorphine and, since these are almost identical, it may be concluded that all the drugs combine with similar receptors. Nalorphine antagonizes both actions by competing for the receptors. It was not possible to antagonize quantitatively the analgesic action of pethidine with nalorphine, although the lenticular effect could be abolished. The effect of nalorphine on the change in skin temperature in mice induced by some of the analgesic drugs was also investigated.

DEEP BODY TEMPERATURE OF UNTETHERED DOLPHIN RECORDED BY INGESTED RADIO TRANSMITTER

Information concerning body temperature was recorded by radio transmission from within a dolphin, Tursiops truncatus, swimming freely in a pool. The temperature varied according to the activity of the animal and appeared to oscillate when the dolphin was returned to the pool after a brief period outside it. The transmitter was passed approximately 17 hours after it had been swallowed. A new type of antenna was used with the circuit. The transmitter can be adapted for telemetering heart beat, movement, aquatic animals.