PHYSIOLOGY AND BIOCHEMISTRY 



confidently expect further advances in this field, which has been 

 widened and cleared even during the present war. 



We have no reliable method for the estimation of insulin in 

 small quantities of blood. Perfection of a technique for this purpose 

 would aid, not only in diagnosing the type of diabetes and perhaps in 

 facilitating the treatment, but in throwing a great deal of light on the 

 very real possibility that insulin concentration in the blood is a factor 

 in the control of insulin liberation from the pancreas. We need either 

 a sensitive chemical test or a microbiological procedure that is capable 

 of detecting the small amounts of the antidiabetic hormone which are 

 certainly present in varying quantities in blood. Thus far, very few 

 vigorous attacks have been made on this important problem. 



Chemistry of Insulin and the Possibility of Synthesis. Ele\ en 

 amino acids have now (1945) been isolated from the crystalline insulin 

 protein. Little progress has been made in the identification of any 

 active chemical grouping which might exert an antidiabetic effect in 

 the absence of the whole insulin molecule. The synthesis of this 

 complex protein awaits further development in protein chemistry; 

 there are so many ways possible in which the various amino acids 

 might be linked that few investigators have thought it worth while to 

 give the matter serious consideration at this time. The problem is 

 attractive enough for its own sake, but when we consider that, if the 

 increase in insulin distribution persists at the present rate, all the 

 available pancreases in the world will be utilized for insulin produc- 

 tion in the not distant future, the situation acquires a new urgency. 

 For the last fifteen years, the total distribution of insulin in the United 

 States and Canada has doubled every five years — that is, the amount 

 used in 1935 was twice that in 1930, the amount in 1940 twice that 

 of 1935, and the same rate of increase has been maintained up to the 

 present time. 



A vigorous search should be made for a source of insulin other 

 than mammalian pancreas. We know that considerable quantities 

 can be obtained from the principal islets of certain fish but this pro- 

 cedure has never been placed upon a commercial basis. 



Etiology of Diabetes. There are no data available to tell us 

 what proportion of diabetic cases is produced by a primary lesion of 

 the pancreatic islet cells. There are many well-substantiated state- 

 ments in the literature which indicate that there is no obvious lesion 



