422 THE BIOCHEMISTRY OF B VITAMINS 



lenged the fact that the pyracins have any biological activity whatsoever 

 in this regard. 



Formylpteroic acid (rhizopterin, SLR factor) is inactive in curing rat 

 leukopenia, and its magnesium salt and the magnesium salt of formylfolic 

 acid, presumably a functional form of folic acid, are both apparently 

 inactive in hematopoiesis in man, 163 as is pteroic acid itself. Indeed, 

 formylpteroic acid is inactive in curing folic acid deficiency in rats or 

 chicks in concentrations 50 times the curative dose of folic acid. The 

 present limited evidence regarding the inefficacy of formylfolic acid in 

 man should be viewed with caution, however. These observations are of 

 interest in view of the inactivity of pteroylpolyglutamates for bacteria, 

 unlike man, and the high activity of formylpteroic acid in some bacteria. 



Pantothenic Acid Deficiency. While there is no acute widespread disease 

 of man now known to be associated with a lack of pantothenic acid, there 

 is great danger in assuming that widespread and dangerous deficiencies 

 of this vitamin do not exist. The function of riboflavin as a vitamin had 

 been well established for a considerable period before it was realized 

 that its lack was responsible for any special difficulty in man — far less 

 the serious consequences that we now associate with ariboflavinosis. The 

 efficacy of pantothenic acid in curing an increasing number of individual 

 cases of various acute symptoms would seem to suggest, therefore, that 

 as diagnostic experience is acquired, pantothenic acid deficiency may be 

 discovered to be a relatively common affliction in man. There is little 

 doubt that pantothenic acid deficiency is commonly present in many con- 

 ditions of malnutrition, and is a frequent complication in beriberi, aribo- 

 flavinosis, and pellagra; and a low blood pantothenic acid level is fre- 

 quently observed in these three conditions. A number of cases of peripheral 

 neuritis and delirium tremens and one of Korsakoff's syndrome that did 

 not respond to other vitamins have apparently responded promptly to 

 pantothenic acid. 



Clear-cut pantothenic acid deficiencies have been produced in a variety 

 of other animals. Indeed before its isolation and identification, this sub- 

 stance unknowingly had been studied by various groups as a factor for 

 weight maintenance in pigeons (vitamin B 3 ) , the chick "anti-dermatitis" 

 factor, and a liver filtrate factor required by rats. 165 



Pantothenic acid deficiency in the chick results in extensive spinal cord 

 lesions, thymus involution, a fatty liver, keratitis, dermatitis, and re- 

 tarded feathering. In black chicks there is a feather depigmentation, and 

 force-feeding chicks on the deficiency diet results rapidly in death. Hens 

 are apparently more resistant to deficiency, but do eventually develop a 

 mild dermatitis of the lower shanks and feet when on a pantothenic acid- 

 free diet. A deficiency of any proportions, however, drastically curtails 



