AbstractsBiology & Animal Science

The lipolytic activity of the duodenal contents

by Bradford North Craver




Institution: Boston University
Department:
Year: 1941
Record ID: 1558248
Full text PDF: http://hdl.handle.net/2144/7174


Abstract

A clinically satisfactory method of lipolytic analysis for the duodenal contents must fulfill eight criteria: (1) and (2) the optimal pH and optimal temperature must be maintained during the course of the reaction; (3) inhibiting agents must be avoided and necessary activators or co-enzymes must be added; (4) operative variables in the system must be held to a minimum by the use of a fixed concentration of a suitable and evenly emulsified substrate; (5) the method of measuring the final extent of digestion must be accurate; (6) the enzyme must be protected from destructive influences in the interim between its procurement and its analysis; (7) the method must be simple, should preferably use ordinary laboratory apparatus and must consume as little time as possible; (8) the method must be designed to give as true a picture as possible of what might be expected to occur in vivo. The following method is presented as more satisfactorily fulfilling these criteria than previously published methods; as substrate serves a 1% tributyrin emulsion rendered permanent by the addition of one gram of Alkanol B per one hundred cc. That is a DuPont product which they kindly stated is alkyl-naphthalene sodium sulfonate. This emulsion is stable after putting it twice through a hand homogenizer and will keep at least one month if kept in the ice box. The only other reagents required are three dilutions of sodium bicarbonate: 1.00%, 1.11%, and 1.25%. The method is one of serial dilution and all analyses are done in duplicate. Ten tubes are set up in pairs to contain the following reagents: tube (1) receives 4 cc. of 1.25% NaHCO3; tube (2) 9 cc. of 1.11% NaHCO3; tubes (3), (4), and (5) 5 cc. of 1.00% NaHCO3. To tube (1) is added 1 cc. of the duodenal specimen to be analyzed and the same to tube (2). After thorough mixing 5 cc. of the contents of tube (2) are added to tube (3). In like manner 5 cc. of the contents of tube (3) are added to tube (4) etc. Five cc. are taken from the last tube of the series and discarded. In working with the duodenal contents a sixth tube is occasionally necessary and with experience one may predict that by noting the speed of digestion in the first tubes of the series immediately after the addition of the substrate. As soon as the various enzymic dilutions have been made, five cc. of the substrate are rapidly added to each tube. The tubes are then all well-stoppered, shaken and incubated in a water bath for two hours. The time interval begins the moment the substrate is added to the first tube and ends the moment the first tube is read in the colorimeter. The tubes should be read in the same order in which they are filled for within narrow limits it takes as long to fill them as it takes to read them in the colorimeter and in that way slight differences in the time of digestion for each tube are held to a minimum. Filter565 is used for the colorimetric readings. Ninety-five per cent, of the light which it transmits lies in the range between 550 and 580 millimicra. For comparative purposes single figures…