Assessment by a two-site enzyme immunoassay of human epidermal growth factor (urogastrone) in the urine of patients with various gastrointestinal diseases including malignant tumors

By using our two-site enzyme immunoassay (EIA) system, the levels of human epidermal growth factor (hEGF) in the urine of patients with various gastrointestinal diseases including malignant tumors were measured. Urinary excretion of hEGF in patients having undergone gastric resection, expressed as a function of creatinine, was found to be somewhat decreased. While the levels of hEGF in patients with gastric cancer were significantly increased. Then, the molecular features of hEGF in the urine of patients with gastric cancer were examined by gel filtration. The elution profile demonstrated that high molecular weight components, which immunologically cross-reacted with hEGF, were considerably increased. On the other hand, the level of normal EGF with a molecular weight of 6500 was decreased to some extent. These results suggest that processing of the EGF precursor into an active EGF molecule is partially suppressed in patients with gastric cancer.

Gastric secretion in rats with chronic gastric fistulae and in stomach-perfused, anesthetized rats

A method of establishing chronic gastric fistulae in rats is described. In rats with chronic gastric fistulae, the basal acid output was 48.8 +/- 2.9 microEq/100 g/hr and the basal pepsin output was 543 +/- 28 micrograms tyrosine/100 g/hr. The effects of urethane-induced anesthesia, pyloric ligation, and acute laparotomy on gastric secretion in rats were examined. Both urethane-induced anesthesia and acute laparotomy depressed gastric secretions. In Ghosh-Schild rats, the basal acid output was 3.2 +/- 0.4 microEq/100 g/hr and the basal pepsin output was 70 +/- 13 micrograms tyrosine/100 g/hr. The persistent and very low level of of gastric secretion in these animals appears to result from the combination of both urethane anesthesia and invasive surgery. Because the rats with chronic gastric fistulae do not require anesthesia, invasive surgery, or pyloric ligation, which may play very important roles in the regulation of gastric functions, this kind of preparation is a suitable method for studying the physiology and pharmacology of gastric secretions in the rat.

Effect of bile acids on the glycoprotein constituent of gastric mucus

The effect of bile acids on the glycoprotein constituent of gastric mucus was investigated. Ghosh-Lai rat stomachs were instilled in vivo for 1 h with buffered saline (control) followed by various bile acids in saline at pH 2.0-7.0. Following quantitative recovery, the instillates were used for the isolation of mucus glycoprotein. The results of analyses revealed that while taurocholic acid exerted essentially identical depletory effects throughout the entire pH range tested, the cholic acid had little depletory effect on the mucus below pH 5.0, and glycocholic acid below pH 4.0. The extent of mucus glycoprotein depletion by bile acids under optimal pH conditions was clearly dependent upon the bile acid concentration as well as its type. The maximum depletory effect with the lowest concentration of bile acid was achieved with taurocholate followed by glycocholate and cholate. Comparison of the depletory effects of mono-, di-, and trihydroxy conjugated and unconjugated bile acids revealed that, within each group, the highest degree of mucus glycoprotein depletion occurred with taurine conjugates. The number of hydroxyl groups on the bile acid molecule appears to exert a less evident effect on the depletory capacity. The results suggest that the in vivo depletion of gastric mucus of its glycoprotein constituent by bile acids depends on the pH of luminal exposure and on the bile acid composition.

Protection by glycerol of urinary l-alanine aminopeptidase activity from freezing and thawing inactivation

L-Alanine aminopeptidase (AAP) and N-acetyl-beta-D-glucosaminidase (NAG) activities in urine are sensitive indicators of renal damage. However, urinary AAP loses its activity during storage in the frozen state. This study proposes a method for preventing the inactivation of AAP by adding glycerol to a final concentration of 10% to a urine sample before freezing and thawing. This study also showed that NAG is stable to freezing and thawing and is not affected by addition of glycerol.

Lipids associated with rat small-intestinal mucus glycoprotein

The lipid content and composition of rat small-intestinal mucus, and the purified mucus glycoprotein before and after Pronase digestion were investigated. The mucus, obtained by the instillation of intestine with 2M NaCl, was fractionated on Bio-Gel A-50 in the presence of 6M urea and the mucus glycoprotein free of noncovalently bound protein was isolated. A portion of the purified glycoprotein was subjected to Pronase digestion to yield glycopeptides. The native mucus, and the purified glycoprotein and glycopeptides were extracted with chloroform-methanol, and the lipids contained in the extracts were analyzed. The lipids accounted for 17.6 of the dry weight of mucus, 26.4 of the mucus glycoprotein, and 25.3% of the glycopeptides. In comparison to mucus, the lipids associated with mucus glycoprotein contained 1.9 times more phospholipids and 2.1 times more glycolipids, showed a 26% increase in neutral lipids, and were virtually free of glycosphingolipids. Treatment of the purified glycoprotein with Pronase led to a moderate (22.3%) loss in neutral lipids, 4.3-fold decrease in phospholipids, and 52.3% increase in glyceroglucolipids. The results indicate that while the interaction of mucus glycoprotein with phospholipids involves its Pronase-susceptible region, the interaction with glyceroglucolipids occurs in the glycosylated region of the glycoprotein that is resistant to proteolysis.

Lipids of supragingival calculus

The matrix of supragingival calculus constitutes 15.7% of the calculus dry weight and contains 54.9% protein and 10.2% lipids. Of the total lipids, 61.8% are represented by neutral lipids, 28% by glycolipids, and 10.2% by phospholipids. The neutral lipids exhibit a high content of free fatty acids (63.9%) and triglycerides (15.8%). The glycolipids are comprised of simple glycosphingolipids (17.2%), mainly lactosyl- and glucosylceramides, and of neutral and sulfated glyceroglucolipids (82.8%). The phospholipids contain large quantities of phosphatidylethanolamine (34.2%) and diphosphatidylglycerol (25.5%). Comparison with salivary and submandibular stone lipids indicates that both saliva and bacteria contribute to the lipid content of supragingival calculus.

Lipid composition of human parotid salivary gland stones

The parotid gland stone matrix constitutes 20.2% of the stone dry weight and contains 8.5% of lipids. Of the total lipids, 74% are represented by neutral lipids, 17% by glycolipids, and 9% by phospholipids. The neutral lipids exhibit a high content of free fatty acids (52.7%) and cholesteryl esters (31.1%). The glycolipids are composed of simple glycosphingolipids (7.1%), and of neutral and sulfated glyceroglucolipids (92.9%). Phosphatidylethanolamine and diphosphatidylglycerol are the principal constituents of the phospholipid fraction.

Covalently linked fatty acids in gastric mucus glycoprotein of cystic fibrosis patients

Undegraded mucus glycoprotein has been isolated in highly purified form from gastric secretion of cystic fibrosis patients. The purification procedure involved gel filtrations on Bio-Gel P-100 and Bio-Gel A-50 and lipid extractions with five mixtures of the organic solvents. The final preparation represented pure glycoprotein as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, cesium chloride density gradient centrifugation, and lipid analysis. Treatment of the pure and delipidated glycoprotein with methanolic KOH or hydroxylamine resulted in liberation of ester-bound fatty acids. Of the total released fatty acids, 95% were represented by hexadecanoate (36.5%), octadecanoate (48.7%), and octadecenoate (8.6%). The quantitative analysis established that, on the average, 12.2 nmol of fatty acids/mg of glycoprotein were released. The studies on cystic fibrotic glycoprotein susceptibility to proteolytic digestion indicated that fraction of glycoprotein which was resistant to pronase digestion contained on the average 33.1 nmol of fatty acids/mg of glycoprotein. After removal of the fatty acid residues from pronase-resistant glycoprotein, by treatment with hydroxylamine, the glycoprotein became susceptible to proteolytic digestion. Thus, in cystic fibrosis, the covalently bound fatty acids interfere with proteolytic degradation of mucus glycoprotein. Perhaps this is the major defect of cystic fibrosis glycoproteins and the cause of the obstruction of secretory glands and the accumulation of poorly soluble secretions.