Pancreatic polypeptide (PP), a recently discovered pancreatic hormone, is potentially a marker for endocrine tumors. Consequently, we devised a radioimmunoassay for it, using antisera (raised in rabbits) to bovine PP, 125I-labeled bovine PP (purified by anion-exchange chromatography), and human PP standards. Concentrations circulating in fasting, normal subjects were measured. Statistical analysis of the results revealed a skewed distribution. An age-related increase was also observed. Evaluating PP concentrations in sera from 23 patients with endocrine tumors, we found increased values in a few cases of Zollinger-Ellison syndrome, medullary carcinoma of the thyroid, carcinoid syndrome, and one tumor producing vasoactive intestinal polypeptide (VIPoma). In contrast, values from five insulinomas and one glucagonoma were within the normal reference interval. Thus, an increased value for PP in a fasting individual may suggest the diagnosis of an endocrine tumor but is not a diagnostic prerequisite.
Abnormal gastric motility has been recognised recently in some patients with excessive gastro-oesophageal reflux. The cause of this motility disturbance is unknown. A dual isotope study has been used to assess gastric emptying of solid and liquid components of a test meal in 16 patients with erosive oesophagitis and in 16 control subjects. The release of insulin, gastrin, pancreatic polypeptide, gastric inhibitory polypeptide and neurotensin in response to the test meal was monitored in all subjects. A significant delay in both solid and liquid emptying was observed in patients with erosive oesophagitis. However, they demonstrated no alteration in the pattern of hormone release in response to the test meal.
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