CHANGES IN THE INTESTINAL WALL 449 



the amount of 30% ; the vitamin A in both hver and plasma was even more 

 markedly decreased. Good\vin-° suggests that this effect may be due to an 

 active factor in the Upid fraction.-"^ 



In addition to thyroxine, the cortical hormones may influence the caro- 

 tene -^ vitamin A change.-"^ It is suggested that this effect is mediated 

 by the adrenal gland, since it does not occur when cortisone is injected into 

 adrenalectomized rats 



Almquist and Maurer-^" observed that certain antibiotics (a mixture of 

 chlortetracycline and diamine penicillin, and chlortetracycline alone) 

 increased the extent of the carotene — »- vitamin A reaction in chicks, as 

 judged by the level of liver vitamin A. Burgess et aZ.^" also noted an 

 increased level of plasma vitamin A and serum carotenoids in twenty-six- 

 day-old chicks which received penicillin G in the diet, but it was uncertain 

 whether the results were related to an increased transformation of carotene 

 to vitamin A or to an improvement in the absorption of carotene. Aureo- 

 mycin was shown to increase the vitamin A stores in the livers of rats, but 

 the reason for the effect is not clear. High-^^ ascribed the increased vitamin 

 A content of the liver when aureomycin was given to an improvement in 

 the carotene — »- vitamin A reaction, since the group receiving carotene with 

 the antibiotic had higher levels of \'itamin A than did the control group, 

 while the deposition of vitamin A in the liver in the group receiving pre- 

 formed vitamin was not affected by the presence or absence of aureomycin 

 in the diet. On the other hand, Murray and CampbelP^* observed that 

 aureomycin exerted a beneficial effect in the case of vitamin A-depleted 

 rats receiving vitamin A acetate, as compared with those not receiving the 

 antiobiotic ; the difference was determined by the vaginal smear assay. 

 The sur\dval time of the female rats, but not of the males, was increased 

 by aureomycin. 



Vitamin B12, also, was reported by High and Wilson- ^^ to increase the 

 deposition of vitamin A from carotene. Because vitamin B12 was ineffec- 

 tive in producing this beneficial effect in the presence of penicillin, while it 



"^ J. C. Shaw, L. A. Moore, and J. F. Sykes, /. Dairy Sci., 34, 176-180 (1951 ). 



»8 R. L. Squibb, C. Y. Cannon, and R. S. Allen, J. Dairy Sci., 31, 421-427 (1948); 

 32, 565-569 (1949). 



209 1. Clark and R. W. Colburn, Federation Proc, 12, 190 (1953). - 



"0 H. J. Almquist and S. Maurer, Arch. Biochem. Biophys., 55, 297-298 (1955). 



*" R. C. Burgess, IM. Cluck, G. Brisson, and D. H. Laughland, Arch. Biochem. Bio- 

 phys., S3, 339-340 (1951). 



212 E. G. High, Federation Proc, U, 437 (1955). 



"3 T. K. Murray and J. A. Campbell, Federation Proc, I4, 446 (1955). 



«»< E. G. High and S. S. Wilson, J. Xutrilion, 50, 203-212 (1953). 



