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Trypsinogen activation peptides (TAP) in peritoneal fluid as predictors of late histopathologic injury in necrotizing pancreatitis of the rat.

The levels of trypsinogen activation peptides (TAP) were quantified by ELISA immunoassay in acute pancreatitis of the rat and compared to the degree of late histopathological sequelae and exocrine functional impairment 4 and 12 weeks after the acute phase of the disease. For this purpose acute pancreatitis of different severity was induced using a suitable rat model recently described. Forty five surviving animals were studied. The level of TAP in peritoneal exudate measured 3 and 6 hr after pancreatitis induction correlated well with the amount of the late histopathological injury at the end of the corresponding observation period (at 4 weeks after 3 hr: r = 0.75, P = 0.003, after 6 hr: r = 0.72, P = 0.005, Pearson; and at 12 weeks after 3 hr: r = 0.86, P = 0.0001, after 6 hr: r = 0.84, P = 0.0001, Pearson). A negative correlation of TAP with the impairment of exocrine function was found only at 4 weeks for the secretion of total protein (r = -0.76 after 3 hr; r = -0.62 after 6 hr) and for exocrine function (r = -0.67 after 3 hr, r = -0.57 after 6 hr), but not at 12 weeks after acute pancreatitis. No correlation with plasma amylase and lipase was found. We conclude that quantitation of TAP in ascites provides an accurate prediction of late histopathologic sequelae. Pancreatic exocrine function could be predicted by TAP assay only in the early stage after pancreatitis induction (eg, four weeks). In later stages of the disease (eg, 12 weeks) remaining pancreatic tissue seems to compensate for any exocrine deficits that have occurred.

Animals↗

Effect of ethylene glycol and polyethylene glycol on the acid-unfolded state of trypsinogen.

Effect of increasing concentrations of two of the polyols, ethylene glycol (EG) and polyethylene glycol (PEG), was studied by near and far circular dichroism (CD), fluorescence emission spectroscopy, and binding of hydrophobic dye, 1-anilino-8-naphthalene sulfonic acid (ANS). Far-UV CD spectra show the transition of acid-unfolded trypsinogen from an unordered state to an intermediate state having ordered secondary structure. Interestingly, near-UV CD spectra show some amounts of stabilizing effect on the tertiary structure of the protein also. Tryptophan fluorescence studies indicate the change in the environment of the tryptophan residues on addition of EG and PEG. Maximum ANS binding occurs in presence of 80% EG and 90% PEG (v/v), suggesting the presence of an intermediate or molten globule-like state at high concentrations of the two polyols.

Anilino Naphthalenesulfonates↗

Mutational screening of the cationic trypsinogen gene in a large cohort of subjects with idiopathic chronic pancreatitis.

Several missense mutations, including R122H, N29I, K23R, A16V and D22G, in the cationic trypsinogen gene (PRSS1), have been associated with certain forms of hereditary pancreatitis (HP). Their occurrence in the idiopathic chronic pancreatitis (ICP) and whether novel mutations could be identified in PRSS1 remain to be further evaluated. These were addressed by the mutational screening of the entire coding sequence and the intronic/exonic boundaries of the PRSS1 gene in 221 ICP subjects, using a previously established denaturing gradient gel electrophoresis technique. Among the known PRSS1 mutations, only the R122H was detected in a single subject and the A16V in two subjects in the cohort, strengthening that HP-associated PRSS1 mutations are rare in ICP. Additional missense mutations, including P36R, E79K, G83E, K92N and V123M, were identified once separately. By analogy with the known PRSS1 mutations, predisposition to pancreatitis by some of them, particularly the V123M autolysis cleavage site mutation, is suspected. Functional analysis is expected to clarify their possible medical consequences.

Amino Acid Sequence↗

Immunoreactive trypsinogen levels in pediatric patients with intestinal failure awaiting intestinal transplantation.

The aim of this study was to evaluate pancreatic function in total parenteral nutrition (TPN)-dependent children with permanent intestinal failure by measuring immunoreactive trypsinogen (IRT) levels. Between 1992 and 1996, 105 pediatric patients with permanent intestinal failure were referred to the Children's Hospital of Pittsburgh for small intestinal transplant evaluation. Serum samples were available from 55 of them. Ten suffered from intestinal pseudo-obstruction or microvillus inclusion disease, while 45 had short bowel syndrome (SBS). IRT levels were significantly higher (p < 0.001) in SBS patients (89.4 +/- 9.2 ng mL) compared to controls (43.4 +/- 5.6 ng/ nL) without liver, gastrointestinal, or kidney disease. IRT levels did not correlate with liver injury, length of bowel, or the cause of SBS. Five of 20 patients who underwent intestinal transplantation developed pancreatitis during a median post-operative follow up 15.4 months later. IRT levels failed to predict who would develop pancreatitis post-transplant. The data suggest that elevated plasma IRT levels are common among children with intestinal failure, but fail to identify patients at risk for pancreatitis post-transplant.

Adolescent↗

Hereditary pancreatitis is caused by a mutation in the cationic trypsinogen gene.

Hereditary pancreatitis (HP) is a rare, early-onset genetic disorder characterized by epigastric pain and often more serious complications. We now report that an Arg-His substitution at residue 117 of the cationic trypsinogen gene is associated with the HP phenotype. This mutation was observed in all HP affected individuals and obligate carriers from five kindreds, but not in individuals who married into the families nor in 140 unrelated individuals. X-ray crystal structure analysis, molecular modelling, and protein digest data indicate that the Arg 117 residue is a trypsin-sensitive site. Cleavage at this site is probably part of a fail-safe mechanism by which trypsin, which is activated within the pancreas, may be inactivated; loss of this cleavage site would permit autodigestion resulting in pancreatitis.

Arginine↗

Hereditary pancreatitis caused by triplication of the trypsinogen locus.

Hereditary pancreatitis has been reported to be caused by 'gain-of-function' missense mutations in the cationic trypsinogen gene (PRSS1). Here we report the triplication of a approximately 605-kb segment containing the PRSS1 gene on chromosome 7 in five families with hereditary pancreatitis. This triplication, which seems to result in a gain of trypsin through a gene dosage effect, represents a previously unknown molecular mechanism causing hereditary pancreatitis.

Adolescent↗

Determination of the relative contribution of three genes-the cystic fibrosis transmembrane conductance regulator gene, the cationic trypsinogen gene, and the pancreatic secretory trypsin inhibitor gene-to the etiology of idiopathic chronic pancreatitis.

In the last 5 years, mutations in three genes, the cystic fibrosis transmembrane conductance regulator (CFTR) gene, the cationic trypsinogen (PRSS1) gene, and the pancreatic secretory trypsin inhibitor (PSTI) gene, have been found to be associated with chronic pancreatitis (CP). In this study, using established mutation screening methods, we systematically analysed the entire coding sequences and all exon/intron junctions of the three genes in 39 patients with idiopathic CP (ICP), with a view to evaluating the relative contribution of each gene to the aetiology of the disease. Our results demonstrate that, firstly, 'gain-of-function' mutations in the PRSS1 gene may occasionally be found in an obvious ICP subject. Secondly, presumably 'loss-of-function' mutations in the PSTI gene appear to be frequent, with a detection rate of at least 10% in ICP and, finally, abnormal CFTR alleles are common: at least 20% of patients carried one of the most common CFTR mutations, and about 10% of patients were compound heterozygotes, having at least one 'mild' allele. Thus, in total, about 30% of ICP patients carried at least one abnormal allele in one of the three genes, and this is the most conservative estimate. Moreover, a trans-heterozygous state with sequence variations in the PSTI/CFTR genes was found in three patients. However, an association between the 5T allele in intron 8 of the CFTR gene and ICP remains unproven.

Chronic Disease↗

Cationic trypsinogen and pancreatic secretory trypsin inhibitor gene mutations in neonatal hypertrypsinaemia.

Neonatal hypertrypsinaemia with normal sweat chloride detected during CF screening may be related to trypsin activation. We have looked for mutations of the cationic trypsinogen (PRSS1) and pancreatic secretory trypsin inhibitor (PSTI) genes in 50 hypertrypsinaemic neonates with known CFTR genotypes and negative sweat test. No mutations were found in either gene. Two silent polymorphisms were detected in the PRSS1 gene. A polymorphism in the promoter region and an intronic polymorphism of the PSTI gene were found. No difference was observed in the frequency of PRSS1 or PSTI polymorphisms in neonates carrying or not carrying CF mutations. These results do not provide an indication for an increased frequency of mutations in the PRSS1 and PSTI genes in this group of neonates with transient hypertrypsinaemia.

Carrier Proteins↗

Calcium-binding constants of trypsin and trypsinogen. A reassessment.

The Ca2+-binding constants for trypsin and trypsinogen have been reassessed by using enzyme that has been purified by affinity chromatography and measuring the distribution of 45Ca2+ between the protein and a cation exchanger. The pKCa2+ value of 4.5 for the high-affinity site on trypsin was 1 logarithmic unit greater than that previously reported.

Calcium↗

Regulation of concentrations of mRNA for amylase, trypsinogen I and chymotrypsinogen B in rat pancreas by secretagogues.

Regulation of pancreatic gene expression by the secretory stimulants cholecystokinin-pancreozymin, caerulein and pilocarpine was studied in the rat, by using cloned cDNA probes to quantify concentrations of specific mRNAs (amylase, trypsinogen I and chymotrypsinogen B). It is concluded that long-term pancreatic stimulation results in pre-translational regulation of secretory-protein gene expression, with a preferential accumulation of RNA transcripts encoding serine proteinases, compared with that for amylase.

Amylases↗

Specificity studies on enteropeptidase substrates related to the N-terminus of trypsinogen.

The specificity of the synthetic substrate Gly-[L-Asp]4-L-Lys 2-naphthylamide originally developed for the assay of enteropeptidase (EC 3.4.21.9), was investigated with partially purified aminopeptidase. Our results indicate that, not only enteropeptidase, but also the concerted action of the aminopeptidases of the rat small intestine, can rapidly release 2-naphthylamine from the substrate. A previously undescribed, highly active, dipeptidylaminopeptidase, which hydrolyses a Gly-Asp dipeptide from the N-terminus of the substrate, was detected in rat small intestine. The resulting [L-Asp]3-L-Lys 2-naphthylamide fragment is then degraded by a combination of aminopeptidase A and N to yield free 2-naphthylamine. Thus the present substrate cannot be regarded as being specific for enteropeptidase, and its use leads to an over-estimation of enteropeptidase activity in homogenates and extracts of intestinal tissue. In order to prevent this non-specific hydrolysis by aminopeptidases, stereoisomeric substrates with the sequence L-Ala-D-Asp-[L-Asp]3-L-Lys methyl ester, D-Ala-[L-Asp]4-L-Lys methyl ester and L-Ala-[Asp]4-L-Lys methyl ester were synthesized and tested as alternative substrates by their ability to inhibit the enteropeptidase-catalysed activation of trypsinogen.

Animals↗

Malnutrition, gastroenteritis and trypsinogen concentration in hospitalised Aboriginal children.

OBJECTIVE: To explore relationships between malnutrition and pancreatic damage in hospitalised aboriginal children. METHODS: Immunoreactive trypsinogen (IRT) concentrations were measured in two populations of hospitalised aboriginal children in Australia: 472 children aged 0-3 years, in Alice Springs (Northern Territory); and 187 children aged 0-16 years in Mount Isa (Queensland). Correlation of whole blood IRT with height and weight z-scores, four-site skinfold thickness and upper arm circumference was sought. RESULTS: In Mount Isa, the geometric mean IRT concentration rose with decreasing weight z-score. The IRT concentration was otherwise unrelated to nutritional indices. Sixty percent of the 39 Mount Isa patients with gastroenteritis and 24.5% of the 358 Alice Springs patients with gastroenteritis had an IRT concentration in the upper quartile for their population, compared with 16% for patients with other diagnoses in both populations. CONCLUSIONS: A high IRT concentration in patients with low weight z-scores is a confounding effect of gastroenteritis, and may result from subclinical pancreatic disease in gastroenteritis.

Adolescent↗

[Diagnosis of a "hereditary pancreatitis" by the detection of a mutation in the cationic trypsinogen gene].

HISTORY AND CLINICAL FINDINGS: A 71-year-old woman was admitted with the suspected diagnosis of pancreatic carcinoma. As a child she had had repeated attacks of abdominal pain of undetermined cause. When aged 48 years she had developed diabetes mellitus. Her now 42-year-old daughter had from the age of 9 years suffered from repeated attacks of acute pancreatitis that had finally led to chronic pancreatitis. The patient's 15-year-old grandchild was having recurrent bouts of abdominal pain. INVESTIGATIONS: Imaging procedures revealed calcifications in the pancreas and an infiltrating space-occupying lesion, about 3 cm in diameter, in the head of the pancreas with lymph node and liver metastases. Cytological analysis of material aspirated from the space-occupying mass showed typical findings of ductal pancreatic carcinoma. FURTHER TESTS, TREATMENT AND COURSE: At first the patient's course was not typical for a genetically-determined disease, but the family history raised the suspicion of hereditary pancreatitis. A genetic test (Afl-III-RFLP test) demonstrated the mutation Arg 117 His in the cationic trypsinogen gene in all diseased or symptomatic family members. The patient died of the complications of the pancreatic cancer. CONCLUSION: Genetic tests are valuable in the diagnosis of hereditary pancreatitis, because the increased cancer risk can be met by frequent examinations in affected family members.

Abdominal Pain↗

Pancreatic function and extended mutation analysis in DeltaF508 heterozygous infants with an elevated immunoreactive trypsinogen but normal sweat electrolyte levels.

BACKGROUND: Newborn screening for cystic fibrosis (CF) with immunoreactive trypsinogen (IRT) and DeltaF508 analysis followed by sweat testing misses some infants with CF and detects more DeltaF508 carriers than expected. Some of the apparent DeltaF508 carriers may be DeltaF508 compound heterozygotes with normal sweat electrolyte levels. METHODS: Infants identified by newborn screening with an elevated IRT level, one DeltaF508 allele, and a sweat chloride level <60 mmol/L underwent CF mutation analysis, pancreatic stimulation testing, and repeat IRT analysis followed by clinical review and repeat sweat test at 12 months. RESULTS: Over a 24-month period we identified 122 DeltaF508 heterozygotes and recruited 57; 4 had borderline sweat chloride levels (40 to 60 mmol/L), 5 (8.8%, 95% CI 1.4, 16.2) had a second CF mutation (R117H), and 11 (20%, 95% CI 10, 30) had the intron 8 5T allele. Three had clinical CF at 12 months (initial sweat chloride levels: 53, 51, and 32 mmol/L). Pancreatic electrolyte secretion in the subjects with a borderline sweat chloride level was similar to that in patients with known CF. CONCLUSION: The excess of DeltaF508 heterozygotes detected by IRT/DNA screening is associated with the presence of a second mutation or the 5T allele in some infants. Screened infants with borderline sweat chloride levels almost certainly have CF, but long-term follow-up of the infants with the genotype DeltaF508/R117H and DeltaF508/5T is required to determine their outcome. In the meantime, newborn screening should be confined to severe mutations associated with classic CF.

Cystic Fibrosis↗

Human cationic trypsinogen. Arg(117) is the reactive site of an inhibitory surface loop that controls spontaneous zymogen activation.

Mutation of Arg(117), an autocatalytic cleavage site, is the most frequent amino acid change found in the cationic trypsinogen (Tg) of patients with hereditary pancreatitis. In the present study, the role of Arg(117) was investigated in wild-type cationic Tg and in the activation-resistant Lys(15) --> Gln mutant (K15Q-Tg), in which Tg-specific properties of Arg(117) can be examined selectively. We found that trypsinolytic cleavage of the Arg(117)-Val(118) bond did not proceed to completion, but due to trypsin-catalyzed re-synthesis an equilibrium was established between intact Tg and its cleaved, two-chain form. In the absence of Ca(2+), at pH 8.0, the hydrolysis equilibrium (K(hyd) = [cleaved Tg]/[intact Tg]) was 5.4, whereas 5 mm Ca(2+) reduced the rate of cleavage at Arg(117) at least 20-fold, and shifted K(hyd) to 0.7. These observations indicate that the Arg(117)-Val(118) bond exhibits properties analogous to the reactive site bond of canonical trypsin inhibitors and suggest that this surface loop might serve as a low affinity inhibitor of zymogen activation. Consistent with this notion, autoactivation of cationic Tg was inhibited by the cleaved form of K15Q-Tg, with an estimated K(i) of 80 microm, while no inhibition was observed with K15Q-Tg carrying the Arg(117) --> His mutation. Finally, zymogen breakdown due to other trypsinolytic pathways was shown to proceed almost 2000-fold slower than cleavage at Arg(117). Taken together, the findings suggest two independent, successively functional trypsin-mediated mechanisms against pathological Tg activation in the pancreas. At low trypsin concentrations, cleavage at Arg(117) results in inhibition of trypsin, whereas high trypsin concentrations degrade Tg, thus limiting further zymogen activation. Loss of Arg(117)-dependent trypsin inhibition can contribute to the development of hereditary pancreatitis associated with the Arg(117) --> His mutation.

Amino Acid Substitution↗

Induction of enterokinase in the rat small intestine following hypersecretion of trypsinogen by chronic trypsin inhibitor feeding.

The interrelationship between trypsin/trypsinogen and enterokinase (EK) was studied in rats following induction of trypsinogen hypersecretion by various agents. Both soybean trypsin inhibitor and para-aminobenzamidine increased intraluminal tryptic activities to a level about twice that found in the control rats. This resulted in an increase in the mucosal and the intraluminal contents of EK in the rat small intestine. On the other hand, in cholecystokinin-treated rats, although there was an increase of intraluminal trypsin, the increase was about 80% less than in the inhibitor-fed rats. Under this condition, there was no effect on the mucosal or the intraluminal EK. These results suggested that substantial increase in intraluminal trypsin/trypsinogen levels (two-fold over control) will increase the mucosal and the intraluminal concentrations of EK in the rat small intestine. Our observation extends previous reports that a decreased level of trypsin/trypsinogen, such as in pancreatic insufficiency, leads to a decrease in mucosal EK. These observations, when taken together, strongly support the modulating role of intraluminal trypsin/trypsinogen levels in controlling the EK concentrations in the small intestine.

4-Aminobenzoic Acid↗

Generation and possible significance of trypsinogen activation peptides in experimental acute pancreatitis in the rat.

Trypsinogen activation peptides (TAP) were quantified by radioimmunoassay in blood, urine, and peritoneal exudate of rats with experimental pancreatitis. Forty-four animals were studied, comprising a control group and four different induction techniques (cerulein, cerulein plus either 2- or 10-min intraductal glycodeoxycholic acid [GDOC] infusion, and cerulein plus intraductal GDOC with enterokinase [EK]). Significantly higher TAP concentrations were found at 6 h (or at death) in plasma and ascites of all pancreatitis groups compared with controls. TAP quantitation in hourly urine samples demonstrated significantly higher concentrations from the third hour onward in the most severe groups and from the fourth hour onward in the cerulein-treated rats. All nonsurviving rats had a plasma TAP of greater than 2.5 nM/L, whereas only 1 of 34 surviving animals had such a concentration (p less than 0.001). A significant stepwise increase in total TAP in ascites was found when comparing the cerulein group, the two GDOC groups, and the EK group (p less than 0.001). Chromatography of samples with a high TAP content demonstrated comigration with synthetic TAP. We conclude that free TAP are present in blood, urine, and peritoneal exudate of rats with experimental pancreatitis of different pathogenesis and that the amount of TAP may be indicative of the severity of the disease process.

Acute Disease↗