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DIASTATIC ACTIVITY IN BLOOD AND URINE. 



CHAELES KEID, M.A., B.Sc, M.B., Ch.B., 

 From the Physiological Laboratory, University of Aberdeen. 



Received for publication June 6th, 1925. 



As views on the utility of the estimation of diastase in urine and blood are 

 divergent, an investigation into the diastase activity of equal quantities of 

 whole blood and urine was undertaken. The diastatic activity of a specimen 

 of urine is estimated in terms of the amount of starch which, incubated at 

 37° C. with a definite volume of the urine, will be changed in 30 minutes, the 

 disappearance of the starch being indicated by the failure of the mixture of 

 starch and urine to give a blue colour or a violet tint with iodine. For the 

 estimation of the diastatic activity of blood, it is necessary to estimate the 

 amount of sugar present in a given amount of blood, to incubate a given 

 amount of blood with a given amount of starch at 37° C. for 30 minutes, and 

 to estimate the amount of reducing sugar which has been formed by the 

 diastase in the blood. The diastatic activity of the blood is given in terms of 

 reducing sugar, and in this way a comparison can be made between the 

 diastatic activities of equal volumes of blood and urine, although the actual 

 concentration of the diastase by the kidneys would not be available. 



Technique. 



Urine. — In order to obtain the diastatic activity of equal volumes of blood 

 and urine, a slight modification of the method described by Dodds (1922) was 

 used. 



A series of ten small test-tubes was employed usually, the length of the tube 

 being about 3 inches, and capacity 4 c.c. A quantity of buffered urine was 

 prepared by mixing 5 c.c. of the urine with 20 c.c. of a mixture of Sorensen's 

 solutions. The buffer solution was obtained by mixing 15 c.c. of a solution 

 containing 11876 grm. Na2HPO42H20 in 1000 c.c. distilled water, and 85 c.c. 

 of a solution containing 9*078 grm. of KH2PO4 in 1000 c.c. distilled water. 

 These solutions were kept in paraffin-coated glass-stoppered bottles. To each 

 of the small ten test-tubes was added 1 c.c. of the buffered urine, and to the 

 series of ten tubes (1-10) were added respectively 2 c.c, 1'8 c.c, 1'6 c.c, 

 1*4 c.c, 1*2 c.c, 1*0 c.c, 0*8 c.c, 0*6 c.c, 0*4 c.c, 0*2 c.c. of a 0*2 per cent, 

 solution of Lintner's soluble starch made up in 0*9 per cent. NaCl solution. 

 The total volume in each tube was made up to 3 c.c by the addition of 

 distilled water. The tubes were shaken immediately, and placed in a water- 

 bath in an incubator for 30 minutes at 37° C. The tubes were then removed 

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