gastrin

The specificity test with synthetic peptides and the chromatographic analysis also provided an explanation: the "false" low concentrations were due to antibodies that recognized only gastrin-17 and not longer or shorter gastrins (Fig.

Gastrin-17 constitutes only a minor fraction of the gastrins in ZES plasma and is, as previously mentioned, even absent in some samples.

When immunoassays that measure the C-terminal epitope of bioactive gastrins (first-line assays) are used, almost all patients with ZES are correctly diagnosed.

For measurement of amidated gastrin concentrations in serum, we used a RIA utilizing an antiserum raised against the C-terminal tetrapeptide sequence common to all bioactive gastrins (9).

Circulating gastrins in gastrinoma patients vary extensively, and the molecular heterogeneity is accordingly unpredictable (4,12).

Serum concentrations of amidated gastrins and the gastrin-17 form in gastrinoma patients.

Pentagastrin is a synthetic pentapeptide containing the carboxyl-terminal tetrapeptide, the active portion found in all natural gastrins. Therefore, it acts as a gastric acid and CT secretagogue (10,11,22).

MTC releases calcitonin (CT) and, occasionally, carcinoembryonic antigen, neuron-specific enolase, serotonin, chromogranin, somatostatin, substance P, pro-opiomelanocortin-derived products, and gastrin (GT)-releasing peptide (2,3).

Control measurements of gastrin in plasma were performed with a RIA using antiserum 2604, which binds all bioactive, carboxyamidated gastrins (gastrin-71, -34, -17, and -14) with equimolar potency irrespective of their degree of sulfation (14, 15).

The single most crucial specificity problem for plasma CCK assays is interference from circulating gastrins. This point was examined in different ways: (a) Chromatography of plasma extracts revealed that antiserum 92128 bound no gastrin (data not shown); (b) no correlation existed between CCK and gastrin concentrations in human plasma samples covering a wide range of concentrations (Fig.

Gastric acid, peptic activities, mucin levels, FT/IC-ATPase activities and the gastrin level were analyzed.

The Rat Pepsin ELISA kits, Rat Gastrin ELISA kits, [H.sup.+]/[K.sup.+] ATPase ELISA kits and Protein assay kits were obtained from Nanjing jiancheng Bioengineering Institute.