CAROTENOIDS AND VITAMINS A IN THE BLOOD 467 



were also increased. However, the proportion of total fat, total phos- 

 phorus, ester phosphorus, thiamine, and vitamin A was decreased. The 

 proportion of jS-carotene in the total carotenoids remained constant in the 

 mastitic milk, and the blood carotenoid level remained essentially un- 

 changed. Goodwin^" suggests that a possible explanation for the high 

 carotene values in milk in mastitis is its specific leakage across the dam- 

 aged glandular epitheUum of the mammary gland. 



Acetonemia in cows has been reported to be associated with a high level 

 of blood carotenoids and a relatively low content of plasma \atamin A;"* 

 one suggestion is that the conversion of carotene into vitamin A is depressed 

 in this condition. Massive doses of vitamin A have been found to reduce 

 the blood carotene to normal, and simultaneously to cause an increase in 

 the level of plasma vitamin A to normal values. ^^^~^^^ However, it 

 should be recalled that plasma carotene is depressed in normal animals, as 

 well, by massive doses of vitamin A. It remains midecided whether or 

 not any abnormality in the sj^ithesis of \ntamin A from carotene is asso- 

 ciated with acetonemia in cows. 



Miscellaneous conditions in which lower than normal carotene figm'es 

 have been reported in blood include fever^^- (in which the level of many 

 other blood components is also depressed), cancer of the gastrointestinal 

 tract, -^^ lepros}^,^*^ and the active phase of pneumonia. ^•^•* The provitamin 

 A has been found to remain unchanged in folliculosis in children ^°^ and in 

 nephrosis. ^^^ The entire subject of blood carotene is more completely dis- 

 cussed in The Lipids, Vol. II, pages 365 to 369 and 486 to 509. 



(2) Vitamins A in the Blood 



a. The Nature of Vitamins A in Blood, (a) Vitamin A-Profein Com- 

 binations. Both vitamin A alcohol and vitamin A ester occur in the blood 

 in combination with protein, -^^■-*'' just as is the case with ;S-carotene and 

 with other carotenoids. According to Gangul}' et al.,^^'' \ntamin A alcohol 

 and \'itamin A ester are associated with different plasma proteins in chicken 

 blood. The ester combines with the least soluble fraction (globulin), 



^^ J. W. Patton, Vet. Med., 39, 271-278 (1944). 



"9 J. W. Patton, Vet. Med., 39, 150-153 (1944). 



3« J. Mackay, Vet. Record, 55, 455 (1943). 



3" A. C. Burt, Can. J. Comp. Med. Vet. Sci., 8, 187-188 (1944). 



"2 H. C. S. Aron, R. M. Craig, C. J. Farmer, H. W. Kendell, and G. X. Schwemlein, 

 Proc. Soc. Exptl. Biol. Med., 61, 271-276 (1946). 



3« I. Ikegaki, Z. Vitaminforsch., 6, 206-209 (1937). 



3" H. W. Josephs, Aw. /. Diseases Children, 65, 712-747 (1943). 



"5 B. M. Kagan, E. M. Thomas, D. A. Jordan, and A. F. Abt, /. Clin. Invest.. 29, 141- 

 145 (1950). 



