Inhibition of endogenous pancreatic enzyme secretion by oral pancreatic enzyme treatment

BACKGROUND: The existence of a feedback mechanism for exocrine pancreatic secretion in humans is controversial. Exclusion of proteases from the duodenum stimulates exocrine pancreatic secretion. Conversely, addition of exogenous enzymes could reduce the enzyme secretion. Further investigation of the feedback mechanism should be performed under the most physiological conditions. In the present study we investigated exocrine pancreatic function by measuring fecal enzyme output in healthy volunteers consuming a normal diet, before and during a time course of exogenous pancreatic enzyme supplementation. MATERIAL AND METHODS: Twenty-five healthy subjects (HS) were given two different doses (30 and 60 FIP proteases kg(-1) d(-1)) divided by the number of meals. In all subjects, fecal elastase-1 (E1) concentrations and chymotrypsin (ChT) activities were measured without and with enzyme supplements after 7 days of treatment. In eight subjects, E1 concentrations and ChT activities were measured daily for 10 consecutive days. The subjects were given a dose regimen of 100 FIP proteases kg(-1) d(-1)(divided by the number of meals) for the first 7 days. RESULTS: Oral pancreatic treatment dose-dependently inhibited endogenous pancreatic secretion measured with the use of E1 concentrations. In both regimen groups, the differences were statistically significant. The exogenous enzymes, which interfere with colorimetric method for ChT, dose-dependently increased ChT output. However, only the higher dose resulted in a statistically significant difference. In the subgroup of eight HS, time-dependent changes of fecal enzyme output occurred with a decrease of E1 concentrations and an increase of ChT activity from the second up to eighth or ninth day of the experiment. CONCLUSION: Exogenous applied pancreatic enzymes, dose- and time-dependently inhibited endogenous pancreatic secretion. The obtained results strongly support the existence of a protease mediated feedback mechanism in humans.     

Acute pancreatitis in sowetan africans

Summary Conclusion In African blacks, acute pancreatitis requiring hospital adminission is a severe disease associated with a high mortality and significant long-term morbidity in surviving patients. Background It has been suggested that acute pancreatitis has a benign course in Africans in contrast to Western populations. The aim of the present study was to ascertain the incidence of acute pancreatitis at Baragwanath Hospital for a 1-yr period and to test the validity of the above hypothesis. Methods One hundred thirty-six patients with acute pancreatitis were retrospectively assessed. Fifty patients were available for a prospective follow-up examination and underwent sonographic and biochemical investigations. Acute pancreatitis was diagnosed if the patient presented with the typical clinical picture and a raised serum amylase level >800 U/L. Results The study consisted of 108 male and 28 female patients. Alcohol was identified as the predominant etiologic factor in 83.1%, biliary disease in 7.4%, and idiopathic causes in 6.6%. Substantial morbidity was encountered in 32.3% and was caused mainly by pancreatic complications, metabolic derangements, alcohol-related symptoms, and respiratory impairment. A portion (10.3%) of the patients developed further pancreatic pathology, such as pseudocysts, necroses, or an abscess. The overall mortality rate was 8.1%. Patients who died had a higher mean serum amylase, and most deaths occurred within 2 d of admission. Prospective follow-up after an average of 9.3 mo revealed serious morbidity in two-thirds of patients. Fifty-two percent suffered from severe abdominal pain, 36% complained of weight loss, and 18% were shown to have a sonographically abnormal pancreas. Fecal chymotrypsin levels indicated exocrine pancreatic impairment in 30.6% This work was presented at the South African Gastroenterology Society on September 12, 1995, in Sun City, South Africa.     

Common variants in the CLDN2-MORC4 and PRSS1-PRSS2 loci confer susceptibility to acute pancreatitis

Background/Objectives

Acute pancreatitis (AP) is one of the most common gastrointestinal disorders often requiring hospitalization. Frequent aetiologies are gallstones and alcohol abuse. In contrast to chronic pancreatitis (CP) few robust genetic associations have been described. Here we analysed whether common variants in the CLDN2-MORC4 and the PRSS1-PRSS2 locus that increase recurrent AP and CP risk associate with AP.

Effect of Apatite Crystals on the Activity of Amelogenin Degrading Enzymes In Vitro

The objective of the present study was to determine the effect of apatite crystals on the activity of amelogenin degrading enzymes in vitro. Current experimental data, together with previous reports support the view that among the different proteinases present in the enamel extracellular matrix, serine proteinase(s) are responsible for the massive degradation of amelogenins during the maturation stage. For our in-vitro experiments we used the recombinant amelogenin M179 as substrate and a “65%-satd. (NH₄)₂SO₄” fraction of enamel proteins as well as chymotrypsin as sources for serine-proteinase activity. We report preliminary experiments of amelogenin proteolysis in the presence of apatite crystals resulting in a different proteolysis pattern when compared to amelogenin proteolysis without apatite crystals. Quantitative analysis of the HPLC peaks corresponding to the proteolysis products indicates that the presence of apatite crystals in the proteolysis solution inhibits the ability of the serine-proteinases to degrade amelogenin. The present observations support the hypothesis that amelogenin degradation correlates with apatite crystal growth during enamel maturation.     

Faecal elastase 1: not helpful in diagnosing chronic pancreatitis associated with mild to moderate exocrine pancreatic insufficiency

Background/Aim—The suggestion that estimation offaecal elastase 1 is a valuable new tubeless pancreatic function testwas evaluated by comparing it with faecal chymotrypsin estimation inpatients categorised according to grades of exocrine pancreatic insufficiency (EPI) based on the gold standard tests, thesecretin-pancreozymin test (SPT) and faecal fat analysis.
Methods—In 64 patients in whom EPI was suspected,the following tests were performed: SPT, faecal fat analysis, faecalchymotrypsin estimation, faecal elastase 1 estimation. EPI was gradedaccording to the results of the SPT and faecal fat analysis as absent,mild, moderate, or severe. The upper limit of normal for faecalelastase 1 was taken as 200 µg/g, and for faecal chymotrypsin 3 U/gstool. Levels between 3 and 6 U/g stool for faecal chymotrypsin areusually considered to be suspicious for EPI. In this study, both 3 and 6 U/g stool were evaluated as the upper limit of normal.
Results—Exocrine pancreatic function was normal in34 patients, of whom 94, 91, and 79% had normal faecal elastase 1 andfaecal chymotrypsin levels (<3 U/g and <6 U/g) respectively. Thirtypatients had EPI, of whom 53, 37, and 57% had abnormal faecal enzymelevels (differences not significant). When EPI was graded as mild,moderate, or severe, 63% of patients had mild to moderate EPI, and37% had severe EPI. In the latter group, between 73 and 91% ofpatients had abnormal faecal enzymes. In the group with mild tomoderate EPI, abnormal test results were obtained for both faecalenzymes in less than 50% of the patients (differences notsignificant). Some 40% of the patients had pancreatic calcifications.There were no significant differences for either faecal enzyme between the two groups with and without pancreatic calcifications. In 62% ofthe patients who underwent an endoscopic retrogradecholangiopancreatography (ERCP), abnormal duct changes were found.Again, there were no significant differences for either faecal enzymebetween the two groups with abnormal and normal ERCP.
Conclusion—Estimation of faecal elastase 1 is notdistinctly superior to the traditional faecal chymotrypsin estimation.The former is particularly helpful only in detecting severe EPI, but not the mild to moderate form, which poses the more frequent and difficult clinical problem and does not correlate significantly withthe severe morphological changes seen in chronic pancreatitis.

Keywords:faecal elastase 1; faecal chymotrypsin; secretin-pancreozymin test; faecal fat analysis; exocrine pancreaticinsufficiency; diagnosis

     

Excretory/secretory chymotrypsin from Lucilia cuprina: purification, enzymatic specificity and amino acid sequence deduced from mRNA

Two chymotrypsin-like proteases were purified from the secretory and excretory material of first-instar larvae of Lucilia cuprina. The hydrolysis of N-succinyl-L-phenylalanine-nitroanilide was used to monitor the purification of these proteases which was achieved by affinity chromatography on soybean trypsin inhibitor-Sepharose followed by anion exchange and hydrophobic interaction chromatographies. The enzymatic specificity of the most abundant protease {Lucilia chymotrypsin b; LCTb) was further defined by determining the amino acid sequence of peptides released from insulin B chain after incubation with LCTb. Peptide amino acid sequences obtained from LCTb were used to design degenerate oligonucleotide primers which, in conjunction with the polymerase chain reaction, enabled cDNA coding for LCTb to be cloned and sequenced. The deduced amino acid sequence of LCTb showed many of the structural features of serine proteases as well as significant amino acid sequence homology with chymotrypsins from a diverse range of species. It is probable that LCTb plays an important role in establishing the myiasis-causing larvae of L. cuprina on host skin as well as providing nutrients for the rapidly growing larvae.     

Complete amino acid sequence of a subunit from rapeseed high molecular weight protein

A subunit (M, 15 600) from the high molecular weight protein from rapeseed was separated and isolated; its purity and homogeneity were ascertained. The subunit was cleaved with cyanogen bromide, trypsin, chymotrypsin, and Staphylococcus aureus V8 protease. The fragments were separated and isolated by polyacrylamide gel electrophoresis, gel filtration, column chromatography on Dowex 1 × 2, and paper electrophoresis. The amino acid compositions of the intact subunit and different fragments obtained from enzymatic and chemical cleavages were determined. The subunit and its fragments were sequenced by manual Edman method. The phenylthiohydantoin amino acids obtained after each step were identified by thin-layer chromatography and ultraviolet spectroscopy. The complete amino acid sequence of the subunit consisting of 125 amino acid residues has been established by the overlapping method.     

Effect of dietary fiber on proteolytic pancreatic enzymes in vitro

Summary Chymotrypsin, trypsin, carboxypeptidase A and B, elastase and enterokinase activities were measured in buffer solutions and in human duodenal juice after incubation with wheat bran, cellulose, guar gum, pectin, psyllium and lignin. The different types of dietary fiber led to inhibition of enzymatic activity in most experiments, e.g., lignin could totally ablish the activity of isolated trypsin and chymotrypsin. Only in enterokinase was there no influence. Inhibition depended on incubation time; the effect was proportional to fiber concentration and inversely related to enzyme level. Treatment of fiber with hydrochloric acid (pH 1.5) and heat (95‡C) destroyed inhibitory activity in some experiments. The effect of lignin on one enzyme (trypsin) was reduced by the addition of another enzyme (chymotrypsin). It is concluded that dietary fiber could affect digestion by inhibiting proteolytic pancreatic enzymes.     

Determination of chymotrypsin in stool by a new photometric method

A photometric method to determine chymotrypsin in stool, equivalent to the titrimetric analysis, was developed. The chymotrypsin concentrations found in healthy children and those with gastrointestinal and pancreatic disease permit the same clinical conclusions as the titrimetrically determined results. In view of its lower technical requirements, this method is suitable for the identification of maldigestion in pediatric and general practice.     

Usefulness of a simple photometric determination of chymotrypsin activity in stools — results of a multicentre study

The usefulness of a new photometric test for the determination of chymotrypsin activity in stools was evaluated in a multicentre study. By release of the enzyme from stool particles with a cationic detergent solution after, in most cases, 3 min of homogenization, a photometric measurement of the enzyme activity is possible both in the clear supernatant after centrifugation and in the diluted stool homogenate. The precision of the activity measurement in stool samples with pathologically lowered and normal chymotrypsin activity is good both for in-series (CV = 2.6%, scatter 0.6-5.7%) and for day-to-day determinations (CV = 7.2%, scatter 3.9-13.9%). The results obtained by the photometric determination also exhibit a close correlation with the values measured by pH-stat titrimetry (r = 0.901). The sample-preparation system with a sample-metering chamber is easy to use and gives good agreement with determinations in which the sample metering was done by weighing out the stool (r = 0.961). The photometric test for detection of exocrine pancreatic insufficiency is easy to perform, inexpensive and does not place any undue stress on the patient.