GASTRIC ANALYSIS 171 



According to this scale of pepsin units 10 may be considered as "normal" peptic 

 activity. These units are about Ko as large as those expressed by the Jacoby- 

 Solms scale. 



Inasmuch as it has been shown 1 that blood serum contains an antipepsin it is 

 said to be advisable to test the gastric juice for blood before determining its pro- 

 teolytic power. However, Dezani 2 claims that the methods for demonstrating 

 antipepsin in the blood are not adequate. 



(3) Given's Modification of Rose's Method. 3 The gastric contents are strained 

 through cheese cloth. Two c.c. are measured by means of an Ostwald pipette 

 into a 25 c.c. stoppered volumetric cylinder, and diluted to the mark with dis- 

 tilled water. Into each of seven small test-tubes (1X10 cm.) is measured, with 

 an Ostwald pipette, i c.c. of a 0.25 per cent filtered pea globulin in 10 per cent 

 sodium chloride solution. To each tube is added i c.c. of 0.6 per cent hydro- 

 chloric acid, also by means of an Ostwald pipette. The tubes are allowed 

 to stand about five minutes, until the maximum turbidity develops. To the 

 first five, distilled water is added as follows: To the first, 0.9 c.c.; to the second, 

 0.8 c.c.; to the third, 0.7 c.c.; to the fourth, 0.6 c.c'.; and to the fifth, 0.2 c.c.; to 

 the sixth and seventh, none. Then there are rapidly added to each test-tube 

 the following amounts of the diluted (1:12.5) gastric juice; to the first, o.i c.c.; to 

 the second, 0.2 c.c.; to the third, 0.3 c.c.; to the fourth, 0.5 c.c.; to the fifth, 0.8 c.c.; 

 to the sixth, i.o c.c.; and to the seventh, i.o c.c. of the diluted juice boiled. These 

 measurements can be accurately made with a i c.c. pipette graduated in o.oi c.c. 

 All tubes are then immersed for 15 minutes in a water-bath at 50 to 52C. At the 

 end of this time, the tube is selected which is clear and contains the least amount of 

 diluted gastric juice. Upon this basis, the peptic activity is calculated as the num- 

 ber of cubic centimeters of 0.25 per cent globulin digested by i c.c. of undiluted 

 gastric juice. For example, if tube 2 containing 0.3 c.c. of a 12.5 times diluted 

 juice be clear, then the result would be expressed: 



Peptic activity =t(i ^-0.3) X 12. 5 = 41. 2. 



Ordinarily this scheme of seven tubes is used, though it is not a rule. If the 

 free acidity be high, sometimes a dilution of ^ 5 is made. The number of tubes 

 used will depend upon the accuracy desired. 



(d) Determination of Tryptic Activity. Trypsin is not a gastric 

 enzyme but occurs in the pancreatic juice (see page 190). In case of 

 regurgitation of intestinal contents through the pylorus trypsin would 

 be passed into the stomach. This regurgitation is doubtless of frequent 

 occurrence and may even be a normal mechanism by which gastric 

 acidity is regulated (see page 153). Trypsin is, therefore, generally 

 present in the contents of the normal human stomach. Inasmuch, 

 however, as trypsin is destroyed by the pepsin-hydrochloric acid of 

 the gastric juice, determinations of this enzyme must be carried out 

 immediately after aspirations of the gastric contents, particularly 

 where the acidity of the latter is high. 



l Ogur(K Biochemische Zeitschrift, 22, 266, 1909. 



'Dezani: Arch. farm. Oper., 22, 287, 1916. 



'Givens: Hygienic Lab. Bull. 101, p. 71, August, 1915. 



