Studies of Gastric Pepsin. I. Methods of Measurement and Factors Which Influence It

Abstract

The study of gastric pepsin has failed to receive adequate consideration for several reasons, but mainly because of the lack of technic for obtaining reliable measurements. We investigated the method originally proposed by Gates (1) and more fully elaborated by Gilman and Cowgill (2), and found it to be accurate and highly satisfactory. In fact, it is more accurate than is needed in clinical practice. We have used this method, with slight modifications, in the investigations reported in this and the following paper. The details of the technic can be obtained from the original article by Gilman and Cowgill (2). In this method one measures the rate of digestion of gelatin from an exposed and developed photographic film. As digestion proceeds, the silver granules in the gelatin are liberated, and the resulting decrease in opacity of the film is taken as a measure of the digestion which has occurred. TECHNICWe use, for the digestion, a cell 11 mm. in diameter and 1.2 mm. in depth turned out of sheet bakelite on a lathe. Its capacity is approximately 0.5 cc. The solution to be tested, diluted with an equal volume of glycine hydrochloric acid buffer of pH 2, is placed in the cell. A small square of the prepared film is then laid over the top of the cell and this is covered by a glass square. The whole is clamped together by means of a spring clothes pin and placed in a water bath the temperature of which is maintained at 250 C. After fifteen minutes the film is removed, washed, and dried, and the change in opacity is determined with a colorimeter. The standard for comparison is a freshly prepared suspension of colloidal silver. The index of peptic digestion is obtained by the use of a nomogram as described by Gilman and Cowgill (2).

Studies of Gastric Pepsin. Ii. Secretion of Pepsin in Cases of Duodenal Ulcer and Pseudo-Ulcer

“…We have estimated the concentration of pepsin by a modification of the Gilman-Cowgill method (2), described in the preceding article (6). As an arbitrary standard of measurement a 1 per cent solution of Armour's 1: 10,000 commercial pepsin was assumed to contain 1,000 units.…”