BIOTIN 



Avidin has been shown to occur not only in the eggs of birds and 

 amphibia, but also in the genital tract, and avidin production can be 

 induced experimentally in the oviduct of sexually immature chicks 

 by the administration of oestrogen followed by progesterone. Ad- 

 ministration of oestrogen alone increased the biotin content of the 

 blood five-fold, and when this was followed by progesterone the 

 amount of avidin in the oviduct increased, but the blood biotin was 

 not affected. ^^'^ It is clear, therefore, that avidin as well as biotin is 

 associated with reproduction. 



Biotin and Fatty Livers 



G. Gavin and E. W. McHenry ^^ claimed that feeding rats with 

 biotin on diets low in cholesterol produced fatty livers containing 0-67 

 to 1-25 % of cholesterol, whilst R. Okey ^^ showed that the addition 

 of biotin to the diet of guinea-pigs doubled the amount of cholesterol 

 in the liver. According to Best et al.,^^ however, biotin produced no 

 selective deposition of cholesterol in the liver. They found, on the 

 contrary, that there was a constant relationship between the ac- 

 cumulation of cholesteryl esters in liver and the deposition of gly- 

 cerides in the liver, and that biotin did not affect this relationship. 

 They therefore suggest that the term " biotin fatty liver " should be 

 abandoned (see page 573). 



Biotin and Pantothenic Acid 



There appears to be a connection between biotin deficiency and 

 pantothenic acid,^' since the symptoms of biotin deficiency induced 

 in weanling rats by administration of succinylsulphathiazole were 

 aggravated when a pantothenic acid deficiency was also present. The 

 feeding of biotin protected the animals against these changes and, in 

 addition, reduced the severity of the symptoms of pantothenic acid 

 deficiency. Furthermore, L. D. Wright and A. D. Welch ^^ observed 

 signs of severe pantothenic acid deficiency, including achromotrichia, 

 when rats receiving a highly purified diet containing all the B factors 

 known to be required by the rat, including pantothenic acid, were 

 treated with succinylsulphathiazole. The symptoms were accom- 

 panied by a marked reduction in the pantothenic acid content of the 

 liver and were relieved by administration of biotin and a folic acid 

 concentrate. Thus the utilisation of pantothenic acid appears to 

 depend on the availability of folic acid and biotin which are not 

 normally required by rats, being apparently synthesised in the gut by 

 bacteria. 



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