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Biomedical subjects

P Fric

Publications and source records attributed to P Fric.

At least 109 records · Page 6Linked to original sources
PubMed1978

Endopeptidase activity of the brush border of human enterocyte.

Succinyl-trialanine-p-nitroanilide (Suc-Ala3-pNA) has been described earlier as a convenient substrate for pancreatic elastase which is not split by trypsin and chymotrypsin. An enzyme activity splitting Suc-Ala3-pNA has been found in the supernatant of the mucous membrane of human small intestine homogenized with Triton X-100.

Cell Membrane↗
PubMed1977

Determination of alpha-amylase activity in duodenal contents with the blue starch polymer.

The use of the blue starch polymer (Phadebas tablets) for the determination of duodenal alpha-amylase is described. 0.05% bovine or human albumin solutions are necessary for dissolution of substrate tablets as well as for dilution of duodenal contents. Concentration and output values of duodenal amylase before and after cholecystokinin-pancreozymin and secretin stimulation display a close correlation of the chromogenic and saccharogenic method. The average error of duodenal alpha-amylase in parallel examinations is low with both methods and their relative accuracy is practically the same. The chromogenic method is considered more simple and rapid.

Amylases↗
PubMed1977

Proof of chymotrypsin activity by a peroral test using a synthetic peptide with a C-terminal P-aminobenzoic acid residue.

The reciprocal relationship between the peroral dose and urinary excretion and the optimum testing load of para-aminobenzoic acid (PABA) and N-acetyl tyrosine peptide (Ac-L-Tyr-PABA), alone and after cholecystokinin-pancreozymin and secretin hormonal stimulation, was studied in rats. Between the peroral test dose of PABA and its urinary excretion there is a constant proportionality which is correlated to the size of the dose and is linear in the dose range up to 50 mg/kg b.w. The situation for Ac-L-Tyr-PABA is similar. Dosage of over 50 mg/kg b.w. do not lead to proportional excretion of the test substance in the urine. I.v. stimulation by cholecystokinin-pancreozymin and secretin, using peroral administration of Ac-L-Tyr-PABA, was not followed by a significant increase in urinary PABA excretion. The optimum peroral load of both PABA and Ac-L Tyr-PABA in the rat is 50 mg/kg b.w. With this dose, 82% of free PABA and 77% of the model peptide PABA excreted in 24 hours is found in the urine after 6 hours, so that for practical purposes this interval is adequate. The findings furnish important information on the possibilities of utilizing the given technique for diagnosing the state of exocrine pancreatic function in clinical practice.

4-Aminobenzoic Acid↗
PubMed1977

Digestive enzymes of the mucosa of the small intestine and trypsin and chymotrypsin proteolytic activity of the intestinal contents of germ-free, monocontaminated and conventional rabbits.

The activity of the membrane-bound enzymes of the microvillous zone of the entreocytes (maltase, sucrase, trehalase, lactase, cellobiase, alkaline phosphatase and leucylaminopeptidase) was studied in mucosal smears from the proximal jejunum, ileum, caecum and sigmoid flexure in a group of control (C) (8) and germ-free (GF) (7) rabbits. The trypsin and chymotrypsin activity of the contents of the ileum, caecum and sigmoid flexure was studied in 6 C, 5 GF and 5 monocontaminated (MC) rabbits. In summing up it can be stated that the individual membrane-bound enzymes have a different gradient in the various intestinal segments of C and GF rabbits and that they differ reciprocally in character. The maximum statistically significant differences between GF and C rabbits were found in the ileum; in the jejunum they were somewhat smaller and in the caecum smaller still (in this localization the difference was C versus GF). Striking differences in the proportion of the individual disaccharidases were found inthe jejunum and ileum of C rabbits compared with GF rabbits, in which, in both these segments of small intestine the relationship maltase greater than sucrase greater than trehalase greater than lactase was preserved. The proteolytic activity of the intestinal contents likewise had a different gradient character in C, MC and GF rabbits. The maximum activities (especially trypsin) were found in MC animals. The microbial flora is one of the factors regulating the enzymatic activities of the microvillous zone of the enterocytes and it also significantly influences the proteolytic activity of the intestinal contents. This influence is particularly marked in the distal part of the alimentary tube.

Animals↗
PubMed1977

Determination of pancreatic elastase with new chromogenic substrates-p-nitroanilides of N-acyltripeptides.

Mal-, Suc- and Glt-(Ala)3-NAp were prepared as new substances for determining pancreatic elastase. The kinetic constants show them to be more satisfactory than the previously described Ac-(Ala)3-NAp. The mean elastase output values after pancreozymin and secretin stimulation of the exocrine pancreas were significantly higher in the control subjects than in patients in whom other secretion values were altered. In agar electrophoresis, hog pancreatic elastase (Merck) formed a single cathodal fraction. One cathodal and one anodal fraction were found in human duodenal contents. Serum, plasma, alpha1-antitrypsin and alpha2-macroglobulin inhibit pancreatic elastase. Elastase-alpha1-antitrypsin complexes are enzymatically inactive, whereas the enzymatic activity of elastic-alpha2-macroglobulin complexes is partly preserved. Both types of complexes are stable and are not dissociated to a major extent in the presence of an excess amount of the other inhibitor.

Anilides↗
PubMed1977

Use of a new synthetic substrate, Nalpha-tosyl-L-arginine-P-nitroanilide (TAPA), for determining trypsin activity in the duodenal contents.

The newly synthesized chromogenic substrate Nalpha-tosyl-L-arginine-p-nitroanilide (TAPA) was used to determine the trypsin activity (as the concentration and output in 20-min samples) of the duodenal contents before and after hormonal stimulation with cholecystokinin-pancreozymin (CPZ) and secretin (S). The results were compared with those obtained by means of Nalpha-benzoyl-D,L-arginine-p-nitroanilide (BAPA) and the Nalpha-tosyl-L-arginine methylester (TAME). The synthetic substrates were compared in 17 subjects with normal and in 8 subjects with pathological CPZ-S test values. A high degree of correlation was found in every case between the values obtained by means of the given substrates and it actually proved possible to determine the conversion coefficients for the trypsin concentration (BAPA = 1.306 TAPA, TAME = 0.509 TAPA) and for trypsin output (BAPA = 1.306 TAPA, TAME = 0.535 TAPA). The results demonstrate the usefulness of our new chromogenic substrate TAPA, which is more readily available and cheaper than BAPA and TAME for determining trypsin activity in biological material.

Adult↗
PubMed1976

p-Nitroanilides of 3-carboxypropionyl-peptides. Their cleavage by elastase, trypsin, and chymotrypsin.

Fourteen 3-carboxypropionyl-tripeptide-p-nitroanilides of the general formula 3-carboxypropionyl-alanyl-alanyl-Y-p-nitroanilide (Y = glycine, norvaline, S-methylcysteine, valine, norleucine, S-ethylcysteine, methionine, leucine, isoleucine, phenylalanine, tyrosine, S-benzylcysteine, Calpha-phenylglycine, and proline) were synthesized and their cleavage by elastase, trypsin, and chymotrypsin (Km, kcat and kcat/Km) was determined. The significance of amino acid residues in the position of Y was evaluated firstly with respect to their structure (topographically), and secondly with respect to their free energy (thermodynamically). The alanine residue substrate was cleaved best by elastase, the phenylalanine substrate by chymotrypsin. Trypsin cleaved two substrates only, that is those containing a phenylalanine and a tyrosine residue. The optimum length of the elastolytic substrates was studied in a series of N-3-carboxypropionyl-(Ala)n-p-nitroanilides (n = 1, 2, 3, 4, 5), N-3-carboxypropionyl-(Gly)n-p-nitroanilides (n = 1, 2, 3), and in p-nitroanilides of fatty acids with two to seven carbon atoms. Elastase cleaved tri, tetra, and pentapeptides of alanine. p-Nitroanilides of the glycine series, as well as p-nitroanilides of fatty acids were not cleaved. 3-Carboxypropionyl-tetra-alanine-p-nitroanilide was the most suitable substrate so far found for elastase cleavage; it is not cleaved by trypsin nor chymotrypsin. The optimum distance between Y and the terminal anionic carboxyl residue was found to be 1.8 nm in elastolytic substrates.

Anilides↗