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Different responses of serum cationic trypsinogen to secretin and bombesin in normal subjects and patients with chronic alcoholic pancreatitis.

We evaluated the behavior of serum cationic trypsinogen (SCT), an enzyme of solely pancreatic origin, in 30 patients with chronic pancreatitis and 25 healthy subjects as a control, after secretin and bombesin stimulation. After both the stimulations, serum cationic trypsinogen is unable to distinguish between the healthy control subjects and the patients with chronic pancreatitis. On the other hand, after secretin, the enzyme is able to separate chronic pancreatitis patients with different levels of exocrine function insufficiency. It does so with a greater statistical significance than that obtained by the rapid injection of bombesin and equal to that of trypsin into the duodenal juice during duodenal intubation. For these reasons, as well as the absence of any side-effects, secretin is preferred to bombesin stimulation in the evaluation of the exocrine pancreatic function in patients with chronic pancreatitis.

Adult↗

Spontaneous activation of pancreas trypsinogen in heat shock protein 70.1 knock-out mice.

OBJECTIVES: Heat shock proteins (Hsp's) protect cellular proteins in response to injury, and the role of Hsp70 in experimental pancreatitis was recently described. To find out the possible role of Hsp70 in pancreatitis, we used Hsp70 knock-out mice (Hsp70.1-/-) and wild-type mice (Hsp70.1+/+). METHODS: We studied enzymes activities, Hsp70 protein levels, and histologies in cerulein-induced pancreatitis of Hsp70.1-/- and Hsp70.1+/+ mice. RESULTS: In the basal state, Hsp70 protein levels were higher in Hsp70.1+/+ than in Hsp70.1-/- mice, and trypsin activity was higher in Hsp70.1-/- than in Hsp70.1+/+ mice. The zymogen/lysosome ratio of cathepsin B activity before cerulein injection was higher in Hsp70.1-/- than in Hsp70.1+/+ mice. The expression level of Hsp70 in the pancreas increased in both of Hsp70.1-/- and Hsp70.1+/+ mice after hyperthermia because of the Hsp70.3 gene left intact in Hsp70.1-/- mice. After cerulein hyperstimulation, trypsin activity increased 2-fold in Hsp70.1+/+ mice, but cerulein did not further increase basally elevated trypsin activity in Hsp70.1-/- mice. Hyperthermia pretreatment not only blocked cerulein-induced trypsinogen activation, pancreatic edema, and vacuolization in Hsp70.1+/+ mice, but also decreased basally elevated trypsin activity in Hsp70.1-/- mice. CONCLUSIONS: Hsp70 can be responsible for inhibition of cerulein-induced pancreatitis and prevention of spontaneous trypsinogen activation in mice by inhibiting the colocalization of zymogen and lysosomal enzymes.

Animals↗

Mutations of the cationic trypsinogen gene in hereditary and non-hereditary pancreatitis.

BACKGROUND/AIMS: Mutations in the cationic trypsinogen gene have been detected in patients with hereditary pancreatitis (HP). This study investigates the prevalence of the R122H, N29I, A16V and -28delTCC mutations in the common, non-hereditary forms of chronic pancreatitis and in a HP family. METHODS: DNA was prepared from blood samples of 53 patients with chronic pancreatitis (36 alcoholic, 14 idiopathic and 3 hereditary), 20 alcoholic controls and 20 healthy, ethnically matched controls. The R122H and A16V mutations were identified by the polymerase chain reaction (PCR) and restriction enzyme digestion. A nested-PCR was used to identify the N29I mutation. The -28delTCC deletion and the C133807T polymorphism were sought by direct sequencing. RESULTS: The R122H mutation was detected in 1 patient with alcoholic chronic pancreatitis and all 3 affected members of a HP family. The N29I, A16V and -28delTCC mutations were not detected in any of the study subjects. At the C133807T polymorphism, the C allele and C/C genotype were significantly increased in alcoholic chronic pancreatitis (p = 0.001 and p = 0.0004, respectively) while the T allele and CT genotype were significantly reduced (p = 0.001 and p = 0.004, respectively) compared to healthy controls. CONCLUSIONS: Mutations of the cationic trypsinogen gene are rarely found in chronic pancreatitis patients of typical aetiology. Screening for these mutations should be considered in those with a family history consistent with hereditary pancreatitis but may also be appropriate in a well-defined subgroup of patients with non-hereditary chronic pancreatitis, i.e. those who have developed the disease before the age of 30.

Adult↗

Characterisation of a transgenic mouse expressing R122H human cationic trypsinogen.

BACKGROUND: The R122H mutation of the cationic trypsinogen was found in patients with hereditary pancreatitis. A transgenic animal carrying this mutation could be useful as a genetic model system of pancreatitis. METHODS: Mice transgenic for the human R122H cationic trypsinogen were generated using the -205 fragment of the rat elastase promoter. The presence of the transgene was assayed in the DNA, in pancreatic mRNA and in zymogen granule lysates. Serum levels of amylase, lipase and cytokines (MCP-1, IL-6) were monitored and the histological appearance of the tissue was investigated. Pancreatitis was induced by 7 hourly injections of 50 mug/kg cerulein. The procedure was repeated twice weekly for 10 consecutive weeks. The animals were sacrificed 24 (n = 8) and 48 hours (n = 8) after the first injection and at the end of the whole treatment (n = 7). RESULTS: The transgene was detected at the genomic level and in pancreatic mRNA. The corresponding protein was found in low amounts in zymogen granule lysates. R122H mice showed elevated pancreatic lipase, but there was no spontaneous development of pancreatitis within 18 months. After induction of pancreatitis, levels of lipase (after 24 hours) and amylase (after 48 hours) were higher in R122H mice compared to controls. Repeated treatment with cerulein resulted in a slightly more severe pancreatitis in R122H animals. Amylase, lipase, and the cytokine levels were similar to controls. CONCLUSION: The R122H transgenic mouse failed to develop a spontaneous pancreatitis but a repeatedly provoked cerulein-induced pancreatitis led to a slightly more severe pancreatitis. The rather small difference in comparison to controls could be due to the low expression of the transgene in the mouse pancreas.

Amylases↗

Secretin/cholecystokinin-stimulated secretion of trypsinogen and trypsin inhibitor in pure human pancreatic juice collected by endoscopic retrograde catheterization.

Pure pancreatic juice was collected by endoscopic retrograde catheterization of the papilla of Vater from 10 fasting patients without known pancreatic disease. Secretin was given intravenously as a bolus dose at the beginning of the examination and cholecystokinin was given in the same way 15 min later. The juice was siphoned for 25 min and collected in 1-min fractions. Pancreatic secretory trypsin inhibitor, PSTI, and trypsinogen were measured by an immunochemical method. Secretin produced an increase in hydrogencarbonate and a decrease in chloride secretion. Cholecystokinin caused a prompt increase in the concentration of both PSTI and trypsinogen. The ratio between these was constant, suggesting a strictly parallel secretion. The effect of cholecystokinin on secretion of total protein when given as bolus dose was of short duration, with a half-life of action of about 3.5 min.

Ampulla of Vater↗

activated polyamine catabolism in acute pancreatitis: alpha-methylated polyamine analogues prevent trypsinogen activation and pancreatitis-associated mortality.

Polyamines are essential for normal cellular growth and function. Activation of polyamine catabolism in transgenic rats overexpressing spermidine/spermine N(1)-acetyltransferase, the key enzyme in polyamine catabolism, results in severe acute pancreatitis. Here, we investigated the role of polyamine catabolism in pancreatitis and studied the effect of polyamine analogues on the outcome of the disease. Polyamine depletion was associated with arginine- and cerulein-induced pancreatitis as well as with human acute necrotizing and chronic secondary pancreatitis. Substitution of depleted polyamine pools with methylspermidine partially prevented arginine-induced necrotizing pancreatitis whereas cerulein-induced edematous pancreatitis remained unaffected. Transgenic rats receiving methylated polyamine analogues after the induction of pancreatitis showed less pancreatic damage than the untreated rats. Most importantly, polyamine analogues dramatically rescued the animals from pancreatitis-associated mortality. Induction of spermidine/spermine N(1)-acetyltransferase in acinar cells isolated from transgenic rats resulted in increased trypsinogen activation. Pretreatment of acini with bismethylspermine prevented trypsinogen activation, indicating that premature proteolytic activation is one of the effects triggered by polyamine depletion. Our data suggest that activation of polyamine catabolism is a general pathway in the pathogenesis of acute pancreatitis and that experimental disease can be ameliorated with stable polyamine analogues.

Animals↗

Comparison of urine trypsinogen-2 test strip with serum lipase in the diagnosis of acute pancreatitis.

BACKGROUND/AIMS: The accuracy of a new rapid urinary trypsinogen-2 test strip (actim Pancreatitis) was compared with that of serum lipase for detection of acute pancreatitis in patients with acute abdominal pain. METHODOLOGY: A prospective study was conducted which consisted of 237 consecutive patients with acute abdominal pain admitted to the emergency unit at Helsinki University Central Hospital. The patients were tested on admission with the actim Pancreatitis test strip. Serum amylase, serum lipase, and urine trypsinogen-2 concentrations were also determined quantitatively. RESULTS: The actim Pancreatitis test strip result was positive in 27 out of 29 patients with acute pancreatitis (sensitivity 93%) and in 16 of 208 patients with non-pancreatic abdominal pain (specificity 92%). This was superior to that of serum lipase (sensitivity 79% and specificity 88%). With a cut-off > 3x the upper reference limit, the sensitivity of serum lipase was only 55% while the specificity was 99%. The high sensitivity for the actim Pancreatitis test strip resulted in a very high negative predictive value of 99%. All six patients with severe acute pancreatitis were detected by the dipstick. With a higher cut-off value (> 3x upper reference limit) for lipase, two patients with severe acute pancreatitis remained undetected. Combining the actim Pancreatitis dipstick with serum lipase a positive predictive value of 94% was obtained. CONCLUSIONS: Acute pancreatitis can be excluded with a higher probability with the actim Pancreatitis strip than with serum lipase determination, and therefore appears to be more suitable for screening of acute pancreatitis. With its high specificity with a cut-off > 3x the upper reference limit, serum lipase is suitable as a confirmatory test for pancreatitis when a positive dipstick result is obtained.

Abdominal Pain↗

[Starting mechanisms of trypsinogen activation in acute pancreatitis].

Early events critical for the development acute pancreatitis are considered. The possible initiating mechanisms of intracellular trypsinogen activation are discussed. Essential attention is paid to the role of cathepsin B, intraacinar [Ca2+] increase and free radicals generation in the premature zimogen activation. It is demonstrated, that the trypsinogen activation alone may not be sufficient to cause acinar cell injury. Some factors, other than active trypsin, play a main role in the pancreatic damage and in the development of systemic complications of acute pancreatitis.

Acute Disease↗

[Serum cationic trypsinogen: marker of exocrine pancreatic dysfunction in children with protein-calorie malnutrition].

Serum cationic trypsinogen, a non invasive, sensitive test to evaluate the exocrine pancreatic function was measured by radioimmunoassay in 31 children with different degrees of protein-calorie malnutrition (mild, moderate, severe) in whom mean serum albumin values were 3.7 +/- 0.7 g%; 3.1 +/- 0.9 g%; 2.3 +/- 0.4 g%, respectively and in a control group of 20 well-nourished children with mean serum albumin values of 3.9 +/- 0.7 g%. Mean serum trypsinogen levels were significantly elevated in children with malnutrition (mild: 28.5 +/- 2.4 ng/ml, moderate: 31.86 +/- 3.4 ng/ml, and severe: 36.52 +/- 7.8 ng/ml) compared with the mean values in the control group (17.7 +/- 2 ng/ml). (p < 0.001). We conclude that our results suggest evidence of a pancreatic damage in malnourished children and this disfunction increases according to the degree of malnutrition, allowing to be detected with this simple test even when the patient does not present qualitative steatorrhea.

Child↗

Processing of pro-colipase and trypsinogen by pancreatic dipeptidyl peptidase IV.

Purified dipeptidyl peptidase IV from porcine pancreas or from human placenta cleaves N-terminal dipeptides from two proteins of the pancreatic juice, namely trypsinogen and pro-colipase. Phenylalanyl-proline is very effectively released (Km approximately 50 microM) from bovine or porcine trypsinogen. Both purified dipeptidyl peptidases also rapidly cleave valyl-proline from the N-terminus of porcine pro-colipase. This degradation does not increase the colipase activity of the precursor. However, under certain conditions, which are not fully understandable at present, dipeptidyl peptidase IV releases more slowly a second dipeptide, aspartyl-proline, from pro-colipase, and this results in a partial activation. Dipeptidyl peptidase IV apparently lines the excretory ducts of porcine pancreas and, therefore, is in close contact to the proteins of pancreatic juice in vivo. The possible significance of these degradations is discussed.

Amino Acids↗

[Effect of trypsinogen on the secretion of the gastric glands].

In chronic experiments on dogs, i. v. administration of trypsinogen (5 mg) raised enzyme--secreting activity of the gastric glands. An increase in pepsinogen secretion by the gastric glands was noted also in acute experiments early after ligation of pancreatic ducts when tryptic activity of the blood was rising. The activating effect of trypsinogen was also revealed on the rat stomach in vitro.

Animals↗

Immunocytochemical distribution of trypsinogen and pancreatic secretory trypsin inhibitor in normal and neoplastic tissues in man.

Immunoreactive trypsinogen and pancreatic secretory trypsin inhibitor (PSTI) were demonstrated in pancreas by means of an immunoperoxidase technique. They had the same distribution in acinar cells of 'normal' human exocrine pancreas tissues. Ductal adenocarcinoma tissue and pancreatic undifferentiated carcinoma contained neither antigen. Scattered 'normal'-looking cells in the border area between normal and neoplastic tissue of both types of tumor stained positively for trypsinogen and for PSTI.

Adenocarcinoma↗

Evidence for extraluminal trypsinogen activation in three different models of acute pancreatitis.

BACKGROUND: Inappropriate extraluminal activation of trypsin is assumed to play a part in the pathogenesis of acute pancreatitis (AP), but proof has been elusive because active trypsin is transient and difficult to measure. We have previously shown increased levels of trypsinogen activation peptides (TAP), a direct measure of trypsin activation, to correlate with severity of AP, tissue necrosis, and survival in a rodent model induced by cerulein hyperstimulation and bile salt infusion. The present study seeks to show that increased trypsinogen activation also characterizes three other models of experimental AP in rodents to give credence to the generality of the phenomenon and to its potential relevance to human AP. METHODS: Experimental AP was induced in mice by a choline-deficient diet supplemented with ethionine and in rats by creation of a closed duodenal loop or by ligation of the biliopancreatic duct plus physiologic stimulation. TAP were quantified by an immunoassay in tissue and plasma at various time points after onset of AP. RESULTS: In the group with choline-deficient diet supplemented with ethionine a significant increase in tissue and plasma TAP was found at 48 and 72 hours, respectively. In the group with closed duodenal loop significant TAP elevations were found in plasma as early as 6 hours and in the group with ligation of the biliopancreatic duct plus physiologic stimulation at 24 hours. CONCLUSIONS: These experiments provide further evidence that extraluminal protease activation is a pathophysiologic event common to the evolution of various models of experimental acute pancreatitis and therefore increase the likelihood that this phenomenon is important in the human disease as well.

Acute Disease↗

Modifying an enzyme immunoassay of immunoreactive trypsinogen to use time-resolved fluorescence.

A coated microtiter-well, enzyme-linked immunometric assay for quantifying immunoreactive trypsinogen in dried blood spots was modified to use time-resolved fluorescence of europium in place of end-point enzymatic color development as the quantification step. The streptavidin-horseradish peroxidase and color development solutions supplied as packaged reagents were replaced by europium-labeled avidin, and the signal was developed with commercially available enhancement solution and read by time-resolved fluorescence. The change of label from enzyme to europium increased the dynamic range of the assay by about 5-fold, reduced the detection limit 10-fold, and halved the intra- and interassay imprecision. The improved analytical precision and stability of the modified assay resulted in a more precise description of the population distribution of immunoreactive trypsinogen values in newborns, showing less variance in the upper centiles. This effect is of paramount importance when using this assay for neonatal screening for cystic fibrosis.

Avidin↗

Characterization of immunoreactive trypsinogen activation peptide in urine in acute pancreatitis.

CONTEXT: All work on human trypsinogen activation peptide (TAP) in acute pancreatitis has been carried out with the same assay. Despite the extensive use of this original TAP assay, there is no characterization of the TAP-like immunoreactivity measured. OBJECTIVE: The aims of this study were to develop an additional TAP assay and to attempt to characterize the TAP-like immunoreactivity found in the urine of patients with acute pancreatitis. METHODS: Antibodies against the human TAP were prepared using the whole octapeptide APFD4K, conjugated at its N-terminal end. Characterization of the immunoreactivity measured with these assays was performed using gel filtration of human pancreatic juice before and after activation of trypsinogen with enterokinase. RESULTS: After activation of the pancreatic juice, there was a large initial increase in immunoreactive TAP and a decrease 6-24 hours later. Using our antiserum, we found low levels of immunoreactive TAP in urine from patients with acute pancreatitis, although many of these samples contained high levels of immunoreactive TAP when tested with the commercially available TAP kit (Biotrin). The pentapeptide D4K, used as a standard in the Biotrin kit, showed much lower immunoreactivity than the synthetic octapeptide APFD4K in our assay. The octapeptide, however, reacted similarly to D4K in the Biotrin kit assay. CONCLUSION: n Our antibody prepared against the synthetic octapeptide APFD4K is directed against the N-terminal part of the octapeptide and does not recognize the pentapeptide D4K. Immunoreactive TAP in urine in acute pancreatitis is mainly composed of the C-terminal pentapeptide, D4K.

Acute Disease↗

Human trypsinogen in colorectal cancer.

Trypsinogen (TRY), the precursor to the serine protease trypsin, is found in the pancreas and mediates digestive proteolysis in the small intestine. Differential display of cDNAs expressed by human colorectal tumor tissues compared with adjacent normal colonic mucosa identified an isoform of TRY (TRY2) up-regulated in colorectal cancers. Northern blot analysis of RNA isolated from a series of 28 malignant colon tumors and corresponding normal mucosa showed that TRY transcripts were up-regulated 2- to 33-fold in 29% of tumors. Further, TRY mRNA was expressed in 6 colorectal cancer cell lines, with highest levels detected in the metastatic tumor lines SW620 and HT29. Immunostaining for TRY protein expression showed intense immunoreactivity in the supranuclear cytoplasm of colon tumors in 16% of tissue specimens. To evaluate the relative contributions of 2 isoforms of TRY, TRY1 and TRY2, to total TRY mRNA expression, a semi-quantitative multiplex RT-PCR assay was developed. TRY2 mRNA was detected in all 6 colorectal tumor cell lines, whereas TRY1 mRNA was expressed only in the metastatic tumor lines, showing that the high levels of TRY expression in the metastatic tumor lines are likely due to up-regulation of TRY1. Evaluation of TRY1 and TRY2 mRNA expression by multiplex RT-PCR in a series of 20 colon tumor tissues representative of the range of tumor progression showed that TRY2 mRNA was expressed much more commonly than TRY1 mRNA in normal mucosa (26% vs. 6%) as well as in primary tumor tissues (65% vs. 15%). These data demonstrate that TRY2 is the dominant TRY in colon tissue and suggest that up-regulation of TRY1 expression in colon tumors may be associated with a metastatic phenotype.

Colorectal Neoplasms↗

Immunoreactive trypsinogen screening for cystic fibrosis: characterization of infants with a false-positive screening test.

Blood immunoreactive trypsinogen (IRT) is elevated in newborns with cystic fibrosis (CF) and has been used as a neonatal screening test. However, not only is the benefit of early diagnosis unknown, but also the sensitivity, specificity, and time related decline of IRT values have yet to be comprehensively evaluated. This report describes the characteristics of infants with a false-positive IRT in our experience with CF screening of 87,000 infants. The IRT value was elevated in 92 newborns; 13 had a confirmed diagnosis of CF by quantitative pilocarpine iontophoresis sweat testing, and 79 infants did not have CF and were therefore classified as false positives by IRT screening. In order to test the hypothesis that perinatal stress factors are associated with high neonatal IRT values, we evaluated Apgar scores at 1 and 5 minutes. We found that the scores of false-positive infants were significantly lower (P = 0.0004 and P = 0.0102 at 1 and 5 minutes, respectively), compared with infants in the general population. While perinatal asphyxia as reflected by low Apgar scores is an associated factor accounting for an elevated IRT value, the majority of non-CF newborns with an elevated IRT have normal Apgar scores.

Apgar Score↗