sodium-dodecyl-sulfate and Pancreatitis

Chronic calcifying pancreatitis is characterized by the formation of intraductal protein plugs or precipitates and calcified stones in ducts. Similar precipitates may be collected by endoscopic retrograde catheterization of the main pancreatic duct. They are present in the pancreatic juice of alcoholic subjects and patients with chronic calcifying pancreatitis. Protein analysis of these precipitates was performed to try to elucidate the mechanism of stone formation. Two protein fraction were separated by extraction of precipitates. One fraction was easily soluble in saline and contained a small amount of most of the proteins of pancreatic juice. The other fraction was soluble in citrate or ethylenediaminetetraacetate and contained a few proteins with close isoelectric points and identical molecular weight (13,500). These proteins showed immunological identity with the "stone protein" isolated from human pancreatic calculi. Our data demonstrate that the major citrate-soluble protein of precipitates in pancreatic juice is identical with "stone protein". They are strongly support the concept that this protein is the organic matrix of pancreatic stones. Different mechanisms are proposed to explain the phenomenon of protein precipitation that frequently occurs in alcoholic subjects and patients with chronic calcifying pancreatitis.

Topics: Alcoholism; Calculi; Chronic Disease; Electrophoresis, Polyacrylamide Gel; Humans; Immunodiffusion; Isoelectric Focusing; Pancreatic Ducts; Pancreatic Juice; Pancreatitis; Proteins; Sodium Dodecyl Sulfate

The two point test for the determination of lipase by Kurooka et al. (J. Biochem. Tokyo 81, 361-369 (1977)) was studied in detail. This procedure uses 2,3-dimercapto-1-propanol-tributyrate as substrate and Ellman's reagent as an acceptor for the released thiol groups. The time course of the enzymic hydrolysis of the substrate showed a pronounced lag phase, which can be influenced by sodium glycocholate. There is no proportionality between the quantity of added serum and the concentration of released thiol groups. Preincubation of the sample with the esterase inhibitor, phenylmethylsulphonylfluoride, as recommended by the authors, does not completely inhibit the serum esterase activity. The action of sodium dodecyl sulphate, which is included in the system, is not explained; in the continuous titrimetric test with triolein as substrate, it acts as a powerful lipase inhibitor. Using 104 serum samples, significant differences were found between the results from this method and those obtained by the titrimetric determination of lipase. Possible fundamental improvements of this test system, using thioesters as substrate, are discussed.

Topics: Dimercaprol; Esterases; Glycocholic Acid; Humans; Hydrolysis; Indicators and Reagents; Kinetics; Lipase; Pancreatitis; Phenylmethylsulfonyl Fluoride; Sodium Dodecyl Sulfate; Spectrophotometry; Sulfhydryl Compounds