(4) Pepsin.—No direct method is available. The following is sufficient for clinical purposes:
Hammerschlag's Method.—To the white of an egg add twelve times its volume of 0.4 per cent. hydrochloric acid (dilute hydrochloric acid, U.S.P., 4 c.c.; water, 96 c.c.), mix well, and filter. This gives a 1 per cent. egg-albumen solution. Take 10 c.c. of this solution in each of three tubes or beakers. To A add 5 c.c. gastric juice; to B, 5 c.c. water with 0.5 gm. pepsin; to C, 5 c.c. water only. Place in an incubator for an hour and then determine the amount of albumin in each mixture by Esbach's method. Tube C shows the amount of albumin in the test-solution. The difference between C and B indicates the amount of albumin which would be digested by normal gastric juice. The difference between C and A gives the albumin which is digested by the fluid under examination. It has been shown that the amounts of pepsin in two fluids are proportionate to the squares of the products of digestion. Thus, if the amounts of albumin digested in tubes A and B are to each other as 2 is to 4, the amounts of pepsin are to each other as 4 is to 16.
Certain sources of error can be eliminated by diluting the gastric juice several times before testing.
D. MICROSCOPIC EXAMINATION
A drop of unfiltered stomach-contents is placed upon a slide, covered with a cover-glass, and examined with the two-thirds and one-sixth objectives.
Under normal conditions little is to be seen except great numbers of starch-granules, with an occasional epithelial cell, yeast-cell, or bacterium. Starch-granules are recognized by their concentric striations and the fact that they stain blue with iodin solutions.
| FIG. 88.—General view of the gastric contents: a, Squamous epithelial cells from esophagus and mouth; b, leukocytes; c, cylindric epithelial cells; d, muscle-fibers; e, fat-droplets and fat-crystals; f, starch-granules; g, chlorophyl-containing vegetable matters; h, vegetable spirals; i, bacteria; k, sarcinæ; l, budding (yeast) fungi (Jakob). |
Pathologically, remnants of food from previous meals, red blood-corpuscles, pus-cells, sarcinæ, and excessive numbers of yeast-cells and bacteria may be encountered (Fig. 88).
Remnants of food from previous meals indicate deficient gastric motility.