ANEURINE (thiamine) 



excretion tests. Another factor that appears to have been ignored 

 by previous workers is that, when the aneurine intake is changed, the 

 rate of response in the urinary excretion is such that only half the 

 change is completed in ten days. Mickelsen et at. recommended that 

 at intakes between 0-7 and i mg. of aneurine per day, the aneurine 

 excretion is a better indicator of nutritional status than the pyramin 

 excretion, but that outside these limits the pyramin excretion is the 

 more reliable. 



The urinary excretion of aneurine by human subjects maintained 

 on a diet rich in aneurine was reduced when viable fresh bakers' 

 yeast was added to the diet,^^ and pure aneurine hydrochloride in- 

 gested with live yeast was not recovered in the urine.^'** No such 

 depression occurred when the yeast had been boiled in water. 



Blood Concentrations and their Value in Assessing Nutritional 

 Status 



Although urinary excretion following the administration of a test 

 dose has until recently been the accepted procedure for assessing the 

 degree of vitamin B^ deficiency, attempts have also been made to use 

 blood concentrations for assessing nutritional status. Among the 

 first papers reporting the aneurine content of blood were those of 

 A. P. Meiklejohn ^^ and H. M. Sinclair, ^^ who employed the Phycomyces 

 test. The concentration of aneurine in plasma and cerebrospinal 

 fluid varied from o to 1-3 jitg. per 100 ml. and in both instances the 

 aneurine was present in the free state and not as cocarboxylase. The 

 amount of aneurine present in the whole blood of healthy adults was 

 7-4 lb I '4 ftg. per 100 ml. ; values less than 4-5 />tg. per 100 ml. were 

 taken to indicate vitamin B^ deficiency. E. N. Rowlands and J. F. 

 Wilkinson, 3^ using substantially the same method, obtained similar 

 values. They found normal blood to contain 6-5 to 16-5 /xg. per 

 100 ml. and the blood of subjects with alcoholic neuritis, nutritional 

 neuritis, scurvy and malnutrition 5 /xg. per 100 ml. or less. L Magyar ^^ 

 obtained values ranging from i to 15 with an average of 7-6 /xg. per 

 100 ml. for blood serum, and confirmed that the level depended on 

 the dietary intake of aneurine. 



According to R. Goodhart and T. Nitzberg,^^ normal blood contains 

 3-1 to 9*2 with an average of 5-4 /xg. per 100 ml., and a value of less 

 than 3 /xg. per 100 ml. is indicative of vitamin B^ deficiency. They 

 used the yeast-growth method of Atkin, Schultz and Frey, and found 

 that a heat labile factor was present in blood which enhanced the stimu- 

 latory activity of aneurine on yeast ; they were able to eliminate inter- 

 ference from this source by heating the blood at 100° C. for four to 

 five minutes. 



68 



