Sialic acid content and proteolytic activity in gastric juice in humans. An approach for appreciating mucus glycoprotein erosion.

The combined determination in human gastric juice of sialic acid content, a marker of solubilized glycoproteins, and of acidity and proteolytic activity has been performed in 217 gastric secretory studies. Taking 1000 micrograms/h of basal sialic acid output as approximating the upper limit of normal, 33 of 34 normal subjects and 12 of 12 patients without recurrent ulcer after highly selective vagotomy had basal sialic acid output below this value while 139 of 156 duodenal ulcer patients and 15 of 15 patients with Zollinger Ellison syndrome had basal sialic acid output above it. No clear relationship between sialic acid and hydrochloric acid outputs was observed; in contrast, close positive significant correlations were noted between sialic acid and pepsin outputs: r and P values ranging, respectively, from 0.82 to 0.63 and from less than 0.001 to less than 0.02. Measurement of sialic acid output content in basal secretion could thus serve to assess mucus glycoprotein output which appears, in large part, related to gastric juice proteolytic activity.