612 



BIOTIN 



During infection of chicks and ducks with avian malaria, significant 

 changes occurred in the concentration in the plasma of free biotin and of 

 the bound, fat-soluble fraction (see p. 566) with biotin-like activity.^^- ^^ 

 The concentration of free biotin rose to a peak at about the time of the 

 peak parasite number and then returned to normal in the surviving birds. 

 It attained the highest levels in birds which succumbed to the infection. 

 In contrast, the bound fat-soluble fraction first rose and then fell before 

 death to very low levels, reaching zero in several animals. Biotin as such 

 had no effect on P. lophvrae in vitro, while plasma protein fractions rela- 



.S-/.-^>^A i. 1. I 



4 6 



8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 

 Day of infection 



Fig. 9. Mean infections with Trypanosoma lewisi in l)iotin-deficient and norma 

 rats. 



tively rich in fat-soluble fraction inhibited multiplication of the malaria 

 parasite. ^^ These observations leave the mechanism of decreased resistance 

 to infection in biotin deficiency unexplained. 



Caldwell and Gyorgy^^ observed that individual and mean infections of 

 Trypanosoma lewisi within groups of biotin-deficient i-ats showed longer 

 periods in which the trypaiiosomes were increasing in number (Fig. 9). This 

 finding, together with delaj^s in the initial trypanolytic crises and delays in 

 terminating the infections, by comparison with the infections in the normal 

 rats, may be best attributed to a delayed or ([uantitatively or ([ualitatively 

 deficient production of specific antibodies. Indications were also found that 



90 H. C. Lichtstein, H. A. Waisman, K. B. McCall, C. A. Elvohjem, and P. F. Clark, 



Proc. Sac. Exptl. Biol. Med. 60, 279 (1945). 

 " F. E. Caldwell and P. Gyorgj^ /. Infectious Diseases 81, 197 (1947). 



