Vitamin A as an anti-infective agent / by H.N. Green and E. Mellanby.

  • Green, H. N. (Harry Norman)
Date:
[1928?]
Catalogue details

Licence: In copyright

Credit: Vitamin A as an anti-infective agent / by H.N. Green and E. Mellanby. Source: Wellcome Collection.

    2/14 (page 2)
    xerophthalmia in human beings, although related to vita¬ min A intake as suggested by the observations of Mori1 and shown by Bloch,2 is of very rare occurrence, and partly because McCollum, Simmonds, and Becker3 have shown that this eye condition results from dietetic abnormalities other than vitamin A deficiency. Several workers, including Drummond,4 Cramer and Kingsbury,5 and Steenbock,6 have commented on the sus¬ ceptibility to lung infections of animals on vitamin A de¬ ficient diets. In the case of dogs E. Mellanby7 drew atten¬ tion to the development of broncho-pneumonia in animals living on diets deficient in fat-soluble vitamins. He pointed out that this tendency to broncho-pneumonia was indepen¬ dent of the condition of the bones, which is itself an indication of the vitamin D intake. For instance, when cod-liver oil was present in the diet the bones were well calcified and there was no tendency to broncho-pneumonia or atelectasis of the lungs. When butter-fat was the source of fat-soluble vitamin, the bones under certain experimental conditions were soft and portions of the lungs were often in a collapsed state, probably because of muscular paresis, but there was no broncho-pneumonia or other infective condition. When olive oil replaced butter, badly calcified bones, collapse of portions of the lungs, and broncho-pneumonia were commonly found. These results suggested that protection against infection of the respira¬ tory tract was conferred by vitamin A and not by vitamin D. Linked up with the problem of xerophthalmia and other infective conditions is that of the changes in epithelium induced by diets deficient in vitamin A. The first to draw attention to these epithelial changes was Mori8 in 1922, who described them in the larynx, trachea, and ducts of many glands, including the Meibomian, submaxillary, sub¬ lingual, and parotid glands of rats. Xerophthalmia he regarded as being due to the drying of the epithelium resulting from the suppression of activity of the lacrymal glands. Wolbach and Howe9 extended this work of Mori’s and described changes in the pancreatic duct and renal pelvis. They gave a detailed description of histological changes in epithelium, and came to the conclusion that infective changes are not responsible for the epithelial hypoplasia and keratinization, but are secondary to them. The diets used by Mori, and those of Wolbach and Howe, were deficient in vitamins C and D as well as A, but these other deficiencies were not regarded by them as affecting the problem. This complication was eliminated by Goldblatt and Benischek,10 who tested the effect of a simple vitamin A deficiency. By this means they induced metaplasia of columnar, cuboidal, and transitional epithelia to the squamous keratinizing type. When vitamin A was present no changes in the epithelium were observed. In the course of their work they found on making post-mortem examina-