摘要:

A large increase in the ascorbic acid content has been shown to occur in the tissues of the white rat (able to synthesize that vitamin) after prolonged exposure and adaptation to cold (+ 4° to − 4 °C.). The increase in ascorbic acid is much smaller if the rats exposed to low temperatures receive daily supplements of that vitamin. On the other hand, a decrease in ascorbic acid content of the tissues has been found in rats unable to adjust themselves to cold environment. From the above results obtained with the white rat, it seems that the acclimatization to low temperatures—and not only maintenance of life at the same temperatures—requires large quantities of ascorbic acid.That conclusion was confirmed by experiments with guinea-pigs (animals that do not synthesize ascorbic acid); the results obtained show that resistance and adaptation of the guinea-pig to cold environment depend on the amount of ascorbic acid received daily; besides, during the process of acclimatization to cold, more ascorbic acid is retained in the tissues of the guinea-pigs exposed to low temperatures than in the same tissues of control animals kept at room temperature; finally, a direct relation has been observed between adaptability to cold environment and the content of ascorbic acid in the adrenals.

ISSN:1923-4287    

DOI:10.1139/cjr47e-011

出版商:NRC Research Press    

年代:1947

数据来源: NRC

摘要:

A description is given of the construction, use, and accuracy of a simple micropipette suitable for the cutaneous application of vesicants in amounts as small as 1 mgm.

ISSN:1923-4287    

DOI:10.1139/cjr47e-012

出版商:NRC Research Press    

年代:1947

数据来源: NRC

摘要:

Certain aspects of the local and systemic action of mustard gas in the rat were studied. A quantitative investigation was made of the local oedema that developed following the application of 5 mgm. of mustard gas to the skin of the rat. Evidence was obtained that a change in the permeability of the blood vessels situated directly under the dosed surface occurred in less than five minutes after the application of the mustard gas. For 12 to 18 hr. after dosing, fluid accumulated in the vicinity of the site of dosing. The oedema then slowly subsided and 72 hr. after dosing the water content of the skin and subcutaneous tissue in the contaminated region was close to the normal value. When mustard gas was applied to the skin of the mid-lumbar region of the rat, the LD50was found to be between 9 and 12 mgm. per kgm. body weight. The LD50of mustard gas injected subcutaneously in the form of a 0.2% (wt./vol.) solution in sesame oil was between 1.5 and 1.8 mgm. per kgm. body weight. The toxicity of mustard gas to male rats did not appear to differ from its toxicity to female rats. Whereas rats died in a few hours after the cutaneous application of very large doses of mustard gas (600 mgm. per kgm. body weight), the great majority of the animals that died following the application of mustard gas in doses up to 60 mgm. per kgm. body weight did not die until 72 to 120 hr. after being dosed. In these animals, anorexia, progressive loss of body weight, distension of the stomach with fluid, congestion of the intestine, and severe diarrhoea were observed. Effects similar to those just described were observed after lethal amounts of mustard gas up to 6 mgm. per kgm. body weight had been given to rats by subcutaneous injection, and most of these animals died in the period 72 to 120 hr. after being dosed. The administration of sublethal doses of mustard gas rarely gave rise to diarrhoea, and any fall in food and water intake and loss of body weight that occurred were slight and of short duration.

ISSN:1923-4287    

DOI:10.1139/cjr47e-013

出版商:NRC Research Press    

年代:1947

数据来源: NRC