L. Desbaillets

Role of inhibition of gastric mucous secretion in the phenomenon of gastric mucosal injury by indomethacin

SummaryThe purpose of this study was to clarify the mechanism by which the therapeutic use of indomethacin is sometimes complicated by peptic ulceration. Mucous secretions from gastric-antral pouches of 5 dogs were collected before, during, and after the daily administration of 5 mg./kg. of indomethacin. This drug decreased the rate of mucous secretion and lowered the concentration of carbohydrate, particularly sialic acid andl-fucose, in the mucosubstance. Peptic ulcers appeared in 3 animals during the administration of indomethacin. The data suggest that gastric mucosal injury by indomethacin may be due to altered mucosal defense mechanisms.

Influence of Phenylbutazone on Gastric Secretion of Mucus.

Summary This study was undertaken in an attempt to clarify the mechanism by which the therapeutic use of phenylbutazone sometimes causes gastric mucosal injury in the form of hemorrhage, erosions or frank ulcerations. Mucoid secretions from gastricantral pouches of dogs were studied before, during and after the oral administration of phenylbutazone in doses of 100 mg/kg of body weight. This drug decreased the rate of mucus secretions and the carbohydrate to protein ratio in non-dialyzable mucosubstance. The data suggest that gastric mucosal injury by phenylbutazone may be due to altered mucosal defense mechanisms.

Inhibition of gastric mucous secretion by ACTH. An experimental study.

SummaryThe rate of secretion and the biochemical composition of mucus secreted by the gastric antrum of dogs were studied before and during administration of ACTH. ACTH caused a decrease in the rate of secretion of the mucus and an alteration in its biochemical composition, characterized by a decrease in the carbohydrate:protein ratio. The data suggest that ulceration during ACTH administration and during stress may be due to impaired mucosal defense mechanisms.

Human Salivary Glycosidases

Summary The activity of several glycosidases—neuraminidase, α-galactosidase, β-galactosidase, α-glucosidase, β-glucosidase, β-N-acetylglucosaminidase, α-mannosidase, β-glucuronidase, and α-L-fucosidase—was assayed in whole, parotid, and submaxillary–sublingual human saliva as well as in mixed cultures of oral microflora. All of these enzymes were present in whole saliva and, with the exception of α-mannosidase, were also present in mixed broth cultures of oral organisms from the same subjects. Only α-L-fucosidase and β-N-acetylglucosaminidase were found in sterile parotid and submaxillary–sublingual saliva. The latter had peaks of optimal pH activity that differed from those of the corresponding bacterial enzymes recovered from the same subject. Since salivary glycosidases can degrade salivary mucins they may be capable, under certain conditions, of attacking the surface layer of mucus in the stomach.

Glycosidases in Canine Pancreatic Secretion

Summary Several glycosidases present in extracts of pancreatic tissue have been found in pancreatic juice. The corresponding enzyme systems in pancreatic juice and pancreatic tissue extract have identical pH optima and similar curves of pH activity. Velocity-substrate relationships of β-glucosaminidase, β-galactosaminidase, α-D-mannosidase, and α-L-fucosidase in pancreatic juice have been estimated.

Influence of Secretin-Cholecystokinin and Secretin-Pentagastrin on Pancreatic Secretion of Glycosidases

Discussion and Summary We had previously described the presence in canine pancreatic juice of several glycosidase enzyme systems. The present data indicate that the outputs of β-glucosaminidase, β-galactosaminidase, α-mannosidase, and α-fucosidase in pancreatic juice increase in response to pancreatic hormonal stimulation to the same degree as those of trypsinogen and amylase. This suggests that these glycosidase enzyme systems may belong to the physiologic complement of enzyme protein in pancreatic juice. It is, of course, important to recognize that the ability of a glycosidase to remove a glycosyl group from a synthetic substrate, which forms the basis of our enzyme assay, does not prove that the enzyme can release the same group from a naturally occurring large molecular substrate. However, the suggestion of a physiologic role for at least one of these enzymes, β-N-acetylglucosaminidase, is strengthened by our finding (to be reported) that this enzyme releases N-acetylglucosamine from ovomucoid.

Characterization of Whole, Canine Gastric-Antral Mucus

Summary Fresh mucus, collected from the canine gastric antrum, was studied by column chromatography, disc gel and immunoelectrophoresis, as well as by analytical techniques for the measurement of protein and protein-bound carbohydrate concentration in mucosubstance. Approximately 40% of the nondialyzable organic solids in fresh antral mucus consists of serum proteins with representation of all or almost all of the various serum protein fractions. The rate of mucous secretion is augmented and the relative proportions of protein and protein-bound carbohydrate are altered when an indwelling cannula is used for the collection of antral mucus.