276 ASCORBIC ACID 



deficiency. However, the more recent view, derived from x-ray studies, is 

 that, other than in size, there is no real structural difference between retic- 

 ulin and collagen.^^- ^'' ®- 



(a) Studies on the Ascorbic Acid Maintenance Requirement of Normal 

 Collagen. Hunt^' stated that mature collagen in a scar may retrogress if 

 ascorbic acid is subsequently withdrawn from the diet and suggested that 

 the ready reversion of the collagen of scars to its immature form affords 

 an explanation of the breaking down of healed wounds in ascorbic acid 

 deficiency. This observation is in line with the report^^ that reopening of 

 old wounds often occurred in British sailors at times when scurvy was 

 common. Pirani and Levenson^^ found that ascorbic acid is necessary not 

 only for the healing of wounds in guinea pigs but also for the maintenance 

 of scar tissue which had formed in the wounds over a period of many weeks. 

 Morrione^^ has recently presented evidence indicating that scar tissue can 

 break down. Elster^^ studied the problem of the relation of ascorbic acid to 

 the maintenance of collagen, using weanling guinea pigs with an average 

 initial weight of 185 g. He made determinations of the collagen content of 

 lungs, liver, kidneys, spleen, heart, and skeletal muscles of scorbutic ani- 

 mals with normal animals as age and weight controls. He found a lower 

 content of collagen in lungs, liver, and kidneys in the scorbutic animals 

 than in the controls of the same age but not lower than in the controls of 

 the same weight. His results were interpreted as indicating that, "once 

 formed, the fiber seems to be independent of further vitamin C nutrition 

 except in so far as it is destroyed by the usual catabolic actions of the body 

 and requires resyn thesis." 



The difficulty of separating and evaluating growth and maintenance re- 

 quirements of ascorbic acid in relation to the collagen content of tissues 

 is indeed very great, and undoubtedly the problem requires an approach 

 from several different angles. Robertson" found no decrease in the collagen 

 content of skin, liver, kidney, lung, or spleen during the development of 

 acute or chronic scurvy but did find significant losses in teeth and costo- 

 chondral junctions. Later, ^^ he studied the effect of ascorbic acid deficiency 

 on the collagen concentration of newly induced fibrous tissue produced by 

 wounding, by subcutaneous injection of diacetyl phosphate or Irish moss 

 extract, or by wrapping a kidney in plastic. He found that the collagen in 



61 J. Gross, Ann. N. Y. Acad. Sci. 52, 964 (1950). 



62 J. H. Highberger, J. Gross, and F. O. Schmitt, /. A)7i. Chem. Soc. 72, 3321 (1950). 



63 A. F. Hess, Scurvy — Past and Present. J. B. Lippincott Co., Philadelphia, 1920. 



64 C. L. Pirani and S. M. Levenson, U. S. Army Med. Nutrition Lab. Kept. 94 (1952). 



65 T. G. Morrione, Trans. 2nd Conf. on Connective Tissue, New York, p. 159 (1951). 



66 S. K. Elster, J. Biol. Chem. 186, 105 (1950). 



67 W. V. B. Robertson, J. Biol. Chem. 187, 673 (1950). 



68 W. V. B. Robertson, J. Biol. Chem. 196, 403 (1952). 



