Lipase activity in blood following endoscopic pancreatography: demonstration of its pancreatic origin and existence of ductal or acino-venous pathways in man

Amylase, pancreatic isoamylase and lipase in serum before and after endoscopic pancreatography

Serum amylase, isoamylase and lipase were determined in 17 patients with pancreatic or biliary diseases before and after endoscopic retrograde pancreatography (ERP). Within 1/2-2 hours after cannulation of the pancreatic duct, serum lipase was increased to approximately 4 times the upper reference level and normalized almost completely at 24 hours. A much smaller increase was found in amylase and isoamylase. The elevation in enzyme activities was less in patients with abnormal than with normal ERP. The results suggest that lipase is a more sensitive indicator of pancreatic injury than amylase and isoamylase.

Serum pancreatic phospholipase A2 and prophospholipase A2 in acute pancreatitis and after endoscopic retrograde pancreatography

Serum immunoreactive pancreatic phospholipase A2 (IP-PLA2) levels and the proportion of active pancreatic PLA2 in the serum IP-PLA2 were determined by radioimmunoassay with an antibody directed against active human PLA2. The subjects of this study included eight patients who underwent endoscopic retrograde pancreatography (ERP), nine patients with acute pancreatitis, and six healthy controls. The serum IP-PLA2 levels were elevated after ERP and during acute pancreatitis. The amount of active pancreatic PLA2 in the serum was determined after its separation from pancreatic prophospholipase A2 using reverse-phase high-performance liquid chromatography (HPLC). The serum IP-PLA2 was separated into two peaks on reverse-phase HPLC. The one which eluted faster contained the PLA2 activity; the other peak did not. The latter IP-PLA2 peak consisted of pancreatic prophospholipase A2 as judged by HPLC analysis and PLA2 activity determination of the products after treatment with trypsin. The proportion of active pancreatic PLA2 in the serum IP-PLA2 of patients after ERP (13.9 +/- 0.5%) increased slightly compared with that in fasting, healthy controls (8.0 +/- 1.1%). For those with acute pancreatitis, the proportion of active pancreatic PLA2 within 48 hours of hospital admission increased more markedly (44.0 +/- 5.7%) than that after ERP. These findings demonstrate that the proportion of active pancreatic PLA2 in the serum IP-PLA2 markedly increases during the early stage of acute pancreatitis, and that an ERP-induced rise in the intraductal pressure leads to the leakage of pancreatic PLA2 into the circulation, but not to a marked activation of the leaked enzyme.

Non-competitive enzyme immunoassay of human trypsin 1

A sandwich enzyme immunoassay was developed for human pancreatic trypsin 1 using polystyrene balls coated with specific IgG as the first antibody and peroxidase-labeled IgG as the second antibody. The entire assay takes 6 h and the detection limit is 0.5 microgram/l. The assay can be performed on sera samples or on discs carrying dried blood spots. Good agreement was found with a radioimmunoassay kit. This simple assay could be widely applied to confirm the elevated immunoreactive serum trypsin described in newborn children with cystic fibrosis.

Binding between immobilized anti-colipase purified antibodies and colipase. Radioimmunoassay of colipase from pig plasma and pancreatic juice

Procedures for purification of porcine colipase II (Gly6-Gly89) and for obtaining purified anti-colipase antibodies are described. The interactions between antibodies immobilized on an Ultrogel AcA 22 column and colipase were investigated and colipase radioimmunoassay carried out. The immobilized antibody-colipase binding was preserved in the presence of mixed micelles, lipase, or both when added to the elution mixture. Bound colipase maintained its capability of interacting with mixed micelles, but not with lipase in either the presence or the absence of mixed micelles. It could be inferred that the antigenic site(s) is independent of the interfacial recognition site and close to the site of lipase recognition. Results are reported suggesting that one or both colipase histidyl residue-containing sequences are involved as antigenic determinant(s). Immunoreactive colipase, bound to a macromolecular protein complex, was found in the plasma of pig. This finding could be explained by an endocrine 'leakage' of colipase from the exocrine pancreatic cell rather than by passage through the intestinal mucosa.

Alteration of membrane fusion as a cause of acute pancreatitis in the rat

Infusion of supramaximal doses of cerulein induces acute edematous pancreatitis in the rat. Cannulation of the main pancreatic duct does not prevent the formation of the edema but reveals an almost complete reduction of pancreatic flow. Using freeze-fracture techniques and thin-section electron microscopy, earliest structural alterations were observed at membranes of zymogen granules and the plasma membrane. Fusion of zymogen granules among each other leads to formation of large membrane-bound vacuoles within the cytoplasm. These and individual zymogen granules fuse with the basolateral plasma membrane, discharging their content into the interstitial space. The findings indicate severe changes in the specificity of the intracellular membrane fusion process induced by supramaximal doses of a pancreatic secretagogue, which finally result in autodigestion of the pancreas.

Secretin-stimulated trypsin-like immunoreactivity in alcoholics

Serum trypsin-like immunoreactivity (TLI) was studied in alcoholics without evidence of pancreatic disease and in controls. Basal values were 29 +/- 4.6 microgram/l (mean +/- S.E.M) in alcoholics and 23 +/- 4.4 microgram/l in controls (p not significant). The injection of secretin was followed by a significant increase of serum TLI in both groups; the integrated trypsin output (ITO) in the first hour after secretin administration was 947 +/- 403 (mean +/- S.E.M.) in alcoholics and 76 +/- 15 in controls (p less than 0.05). In 9 (75%) of the alcoholics tested, ITO was higher than the highest ITO of controls. The increase of serum TLI after injection of secretin is probably due to secretion and/or regurgitation of trypsinogen into the bloodstream when the pancreas is stimulated with intravenous secretin. In the light of experimental studies on chronic ethanol intoxication in animals, the increased ITO observed in alcoholics may suggest obstruction to pancreatic secretory flow in spite of the absence of any clinical sign of pancreatic disease.