Abstract
That sunlight increases the resistance of rachitic rats to specific infections has been shown. 1 , 2 In view of the known variations, daily and seasonal, in solar energy, it seemed desirable to study the effects of a more constant source of radiant energy.
The flaming C arc (Pan Ray), which has been used in this work when operated at 25-28 A, 55-60 V emits a total energy of 0.797 g. cal. per sq. cm. per minute incident at a distance of 1 meter, which is distributed as follows: ultraviolet 12, luminous 35, and infra-red 53%. 3
The animals used were albino rats of the uniform Wistar Institute strain. The members of the different litters were evenly distributed among the test and control groups. All the animals received the same rachitogenic diet (McCollum 3143) for 50 days. During this period, Groups I, III and IV were irradiated daily for 20 minutes at 1 meter distance, thus receiving 16 g. cal. per sq. cm. This amount of radiation was sufficient to prevent the development of rickets in rats receiving the rachitogenic diet. After 50 consecutive irradiations the animals were skiagraphed to determine that there were no rachitic bone lesions, and were then injected with varying amounts of tetanus toxin (Table I). Control groups II and V received similar injections of toxin but were not irradiated. Roentgenograms of these rats showed marked rachitic lesions.
The toxin solutions were injected into the muscles of the thigh and were always freshly prepared from a stock of dried tetanus toxin. It is shown in Table I that the resistance to tetanus-toxin of the irradiated rats was much greater than that of the non-irradiated controls.
Observations on work being performed in this laboratory, although not final, suggest that C arc irradiation for 20 minutes daily at 1 meter, increases the susceptibility of normal rats to tetanus toxin.
Get full access to this article
View all access options for this article.