Experimental rickets : the effect of cereals and their interaction with other factors of diet and environment in producing rickets / by Edward Mellanby.

Edward Mellanby

Date:: 1925

Credit: Experimental rickets : the effect of cereals and their interaction with other factors of diet and environment in producing rickets / by Edward Mellanby. Source: Wellcome Collection.

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$V. THE INTERACTION OF CEREALS WITH ULTRA- VIOLET RADIATIONS. A. Exposure of the Skin to Ultra-Violet Radiations. The curative effect of exposure of the skin to ultra-violet radia¬ tions of a mercury-vapour lamp on human rickets was demonstrated y Huldschinsky [1.2 a] in 1919, and since that date other investi¬ gators have published confirmatory observations on this subject. Besides the clinical confirmation of these facts by Hess and Uno-er [9 5], and also by Chick, Dalyell and colleagues [13], the matter became a subject of experimental study on animals, more especially on rats. These animals were placed on rickets-producing diets, which were modifications of a type used by Sherman and Pappenheimer 16a], and were exposed at intervals during the experimental period ]0 the radiations emitted either by the sun or by lamps of various forms. The essential characteristics about these diets were that both the fat-soluble vitamin and the phosphorus were deficient. Under these dietetic conditions it was found by Hess, Unger, and Pappen¬ heimer [10] on the one hand, and Shipley, Park, Powers, McCollum, and Simmonds [14] on the other, that exposure to ultra-violet radiations had a strong anti-rachitic effect. Huldschinsky [10 b\ had also found that the action of the radiations was not confined to improvement in bone-calcification of rachitic children, but that in addition they exerted a curative influence in tetany. In the case of the rat experiments Powers, Park, Shipley, McCollum, and Sim¬ monds [lo] found that the sunlight also brought about a greater consumption of food, stimulated activity, improved the appearance, and increased the reproductive capacity. The light influence on the metabolism was, in fact, widespread. Somewhat earlier than the publications of Huldschinsky it had been found that diet played an important part in the aetiology of rickets, and that in particular a substance similar in many properties and in distribution to vitamin A had a potent controlling influence on bone-calcification (E. Mellanby 1 a, b). It became a matter of interest to see in what way the respective influences of diet and exposure to ultra-violet radiations were related to each other so far as the calcification of bone was concerned. The suggestion was made by the American workers that the action of radiation was similar to adding phosphorus to the diet (Hess and Gutman [11], Powers, Park, Shipley, &c. [15]). This suggestion seemed feasible when the experimental results on rats were being considered, but had no meaning from the point of view of human rickets where there was no reason to believe that a dietetic phosphorus deficiency was of importance. It soon became apparent that the effects of ultra-violet radiation were closely similar to those produced by adding a source of vitamin A to a diet previously deficient in this substance. The question then arose as to whether the radiations, striking the skin, brought about the synthesis of this vitamin or that they activized the supplies of this substance already present in the body. It is now probable, as the result of the experimental work on the growth of$