506 V. BLOOD LIPIDS 



has been found to reduce its absorption, as demonstrated by the decrease in 

 plasma carotene levels. 920-922 On the other hand, under similar conditions, 

 the absorption of vitamin A was not appreciably decreased, as judged by 

 the fact that there was no reduction in plasma vitamin A. 921 



According to Ronning and Knodt, 923 sulfonamide therapy is without 

 detrimental effects on the normal vitamin A and carotene utilization in 

 calves, as judged from the constancy of the values of the latter components 

 in the blood plasma. On the other hand, the total plasma carotenoids and 

 the concentration of vitamin A in the liver were significantly elevated in 

 the chick by the administration of dietary penicillin. 924 Crowley and Al- 

 len 925 reported a 14 to 18 microgram per cent increase in blood plasma vita- 

 min A in calves and goats after feeding ethyl alcohol. The extent of in- 

 crease in vitamin A in the plasma was found to be proportional to that 

 stored in the liver; no increase occurred in vitamin A-depleted animals. 

 Shaw 926 observed that the addition of 30% ground raw soybeans to the 

 diet of calves decreased both plasma and liver vitamin A markedly, and 

 plasma carotene to a somewhat lesser extent. 



d. Plasma Carotene and Vitamin A as Indices of Nutritional Status. 

 According to Sinclair, 842 levels of serum carotene below 100 microgram per 

 cent and of vitamin A lower than 21 microgram per cent are considered to 

 be indicative of vitamin A deficiency. However, on a carotene-free diet 

 containing adequate amounts of vitamin A, there is no reason why a value 

 of zero for plasma carotene should indicate any degree of avitaminosis A, 

 provided, of course, that the plasma vitamin A value is normal. You- 

 mans et a/., 847 for example, reported that 33% of the white and 15% of the 

 colored subjects examined in Tennessee had serum vitamin A values lower 

 than 21 microgram per cent. In the North Carolina mill village studied by 

 Yarbrough and Dann, 837 blood carotene was found to be 131 microgram 

 per cent, as contrast with the level of 183 microgram per cent presented 

 by the medical staff, while vitamin A was only 15.3 microgram per cent as 

 contrasted with 21.3 jug- for the medical group. Aykroyd et al. 927 pointed 



920 A. C. Curtis and E. M. Kline, Arch. Internal Med., 63, 54-63 (1939). 



921 B. Alexander, E. Lorenzen, R. Hoffmann, and A. Garfinkel, Proc. Soc. Exptl. Biol. 

 Med., 65, 275-278 (1947). 



922 A. E. Mahle and H. M. Patton, Gastroenterology, 9, 44-53 (1947). 



923 M. Ronning and C. B. Knodt, /. Dairy Set., S3, 424-429 (1950). 



924 R. C. Burgess, M. Gluck, G. Brisson, and D. H. Laughland, Arch. Biochem., S3, 

 339-340(1951). 



925 J. W. Crowley and N. N. Allen, /. Dairy Sci., 36, 156-160 (1953). 



926 J. C. Shaw, J. Dairy Sci., 34, 176-180 (1951). 



921 W. R. Aykroyd, N. Jolliffe, O. H. Lowry, P. E. Moore, W. H. Sebrell, R. E. Shank, 

 F. F. Tisdall, R. M. Wilder, and P. C. Zamecnik, Can. Med. Assoc. J., 60, 329-352 (1949). 



