562 NIACIN 



blacktongue-producing rations is due to riboflavin deficiency rather than 

 nicotinic acid. Man, however, frequently develops a marked "encephalop- 

 athy"^^ with irritability, insomnia, headaches, dizziness, tremor, jerky 

 movements, and rigidity of the body. Altered tendon reflexes, numbness, 

 and later paralysis of the extremities may develop. Insanity may occur if 

 the patients are not treated.^" Alcoholism, with its mental disturbances, 

 and concomitant thiamine deficiency, with its effect on the nervous system, 

 frequently complicates the picture. 



DPN and TPN are known to be required for the biochemical reactions 

 by which the brain obtains energy from fuels such as fructose. It is easy to 

 imagine that a deficiency of these vital coenzymes could impede essential 

 biochemical reactions and permit the accumulation of metabolites such as 

 lactic acid which could cause some of these mental symptoms. However, 

 this is speculation and not experimental fact. Actually, no adequate bio- 

 chemical explanation can be offered for the occurrence of these striking 

 mental abnormalities. 



8. Skin 



One of the most puzzling lesions in human pellagra is the rather typical 

 dermatitis and the pigmentation which usually accompanies it. Man, again, 

 is unique, since these lesions are not seen in deficient animals. It has long 

 been known that the dermatitis occurs principally on those parts of the 

 body normally exposed to the sun and that sunlight frequently precipi- 

 tates the lesions. The suggestion has been made repeatedly that the photo- 

 sensitive skin of pellagrins may be due to a disturbance in porphyrin 

 metabohsm.^^' ^'■^''- This has never been proved (p. 556). Alcoholic pel- 

 lagrins do appear to show an increased amount of coproporphyrin III in 

 their urine and stools, but this does not seem to be specifically related to 

 nicotinic acid.^^- 103-105 



Again, no adequate biochemical explanation can be offered for these 

 interesting phenomena. 



88 N. JoUiffe, K. M. Bowman, L. A. Rosenblum, and H. D. Fein, /. Aiti. Med. Assoc. 

 114, 307 (1940). 



9' U. Bassi, Clin. med. ital. 65, 241 (1934). 



10" P. Ellinger and F. Dojmi, Chemistry & Industry 54, 507 (1935). 

 101 M. Massa, Riforma med. 48, 1669 (1932). 



i°2 T. D. Spies, Y. Sasaki, and E. S. Gross, Southern Med. J. 31, 483 (1938). 

 1" K. Dobriner, W. H. Strain, and S. A. Localio, Proc. Soc. Exptl. Biol. Med. 38, 



748 (1938). 

 1"^ R. Kark and A. P. Meikeljohn, Am. J. Med. Sci. 201, 380 (1941). 

 1" L. A. Rosenblum and N. Jolliffe, Am. J. Med. Sci. 199, 853 (1940). 



