Pancreatic elastase in human serum. Determination by radioimmunoassay

Genetic basis of phenotypic plasticity for predator-induced morphological defenses in anuran tadpole, Rana pirica, using cDNA subtraction and microarray analysis

Anuran tadpoles (Rana pirica) are induced to develop a higher tail and a bulgy body as predator-specific morphological responses when they are exposed to predatory larval salamanders. Subtractive hybridization was performed using induced tadpole body skin and normal tadpoles' body skin. A total of 196 clones showed higher expression, and 104 clones showed lower expression, when they formed bulgy bodies. In the subtraction, carboxypeptidase B, trypsinogen, elastase I, fibrinogen, elastase II, triacyl-glycerol lipase, and alpha1-antitrypsin genes showed lower expression. In contrast, RT-like protein, bullous pemphigoid antigen, phosphoserine aminotransferase, uromodulin, tetranectin, chaperonin-like protein, zinc finger protein, osteonectin, aldehyde dehydrogenase, Sec 23A protein, and ribosomal protein showed higher gene expression. Microarray analysis was also performed using this subtracted cDNA (nine replicates). Results of the microarray data essentially corresponded with those of the subtraction data, and the degree of the suppressed genes was much stronger than that of the expressed genes. Carboxypeptidase B showed the strongest suppression, and its inhibition range was from 1/100 to 3/100 compared with that of control body skin. Strong suppression was also observed with trypsinogen, elastase I, fibrinogen, and elastase II as well. These results can be interpreted as increases of fibrinolysis by strong depression of both carboxypeptidase B and other genes simultaneously, resulting in the retention of blood vessels and facilitating the circulation of blood. Expression was observed in phosphoserine aminotransferase, aldehyde dehydrogenase, RT-related protein, chaperonin-like protein, tetranectin, bullous pemphigoid antigen, uromodulin, and Sec 23A protein. They were significantly (p<0.05) increased and were at least 1.5 times greater compared with the control. From the appearance, it seems that the bulgy shaped body is highly connecting to the bullous pemphigoid (BP) antigen that causes the skin blistering disorder, and tetranectin and uromodulin may be related to the extracell matrix through myogenesis, protein secretion, and ion transport, respectively. Since the RT-related protein gene derived from retrotransposon (L1) is known to disrupt mammalian transcriptomes, retrotransposon may be involved with phenotypic plasticity for morphological defense by Rana prica against predator threat.

Degradation and inactivation of plasma tumor necrosis factor-alpha by pancreatic proteases in experimental acute pancreatitis

BACKGROUND

Release of TNFalpha is thought to play an important role in mediating systemic effects in acute pancreatitis (AP). We have been unable to find an elevation of plasma TNFalpha in AP and hypothesize that it is susceptible to catabolism by circulating pancreatic proteases.

METHODS

(1) AP was induced in Sprague-Dawley rats by cerulein hyperstimulation preceded by intraductal infusion of saline (mild) or glycodeoxycholic acid (severe). Healthy and sham-operated animals served as controls. Severity of pancreatitis was confirmed by histology. Plasma TNFalpha levels were measured at various time points after induction of AP with competitive ELISA. (2) Recombinant rat TNFalpha (rrTNFalpha) was incubated with trypsin, elastase, chymotrypsin and pepsin. Western Blot was performed to visualize TNF degradation. (3) RrTNFalpha was incubated in a concentration and time-dependant manner with proteases and TNF bioactivity was evaluated with a cytotoxicity assay.

RESULTS

(1) Plasma TNFalpha levels in severe pancreatitis were significantly lower than in sham-operated controls after 0.5 and 6 h. (2) Incubation with proteases showed degradation in the presence of trypsin, elastase and chymotrypsin and no effect of pepsin. (3) There was a concentration dependent inactivation of rrTNFalpha in the presence of pancreatic proteases and a complete time-dependent inactivation in the presence of trypsin.

CONCLUSION

Plasma TNFalpha does not rise in experimental AP, and levels are significantly lower in severe pancreatitis compared to sham-operated controls. Our study demonstrates degradation and inactivation of TNFalpha by pancreatic proteases, suggesting that it is unlikely it plays an important role in the development of distant organ failure.

Determination of pancreas injury from bloodstains using human pancreatic elastase III as a marker

A sensitive sandwich enzyme immunoassay for human pancreatic elastase III as a method to identify pancreas injuries from blood or bloodstains was evaluated. The serum levels of human elastase III from healthy adults (n=24) were estimated to be 1.15 +/- 0.6 (+/- SD) ng/ml. The recovery rates of elastase III added to normal human serum were estimated to be 96.3%. Elastase III levels in contents of various digestive organs were assayed and found to be high in the contents of the large intestine. For detection of human elastase III on weapons, samples were prepared from disposable scalpels that had been used to cut skin and skeletal muscle, and then to cut various organs. The mean ratio of elastase III to total protein (ng elastase III/mg protein) on scalpels that had been cut the pancreas (n=11) was 4956+/-3067 (+/- SD), whereas the ratios from other organs were much lower except, in case of several digestive organs. The higher elastase III levels detected in these digestive organs seemed to stem from the amount of intestinal contents adhering to the scalpels. These results suggest that determination of pancreatic elastase III in blood or bloodstains using a sandwich enzyme immunoassay is a very useful and effective tool for identification of pancreas injury in forensic practice.

Phospholipase A2: its usefulness in laboratory diagnostics

Phospholipase A2 (PLA2) is an enzyme that catalyzes the hydrolysis of membrane phospholipids. This article reviews the source and structure of PLA2, the involvement of the enzyme in various biological and pathological phenomena, and the usefulness of PLA2 assays in laboratory diagnostics. Of particular importance is the role of PLA2 in the cellular production of mediators of inflammatory response to various stimuli. Assays for PLA2 activity and mass concentration are discussed, and the results of enzyme determinations in plasma from patients with different pathological conditions are presented. The determination of activity and mass concentration in plasma is particularly useful in the diagnosis and prognosis of pancreatitis, multiple organ failure, septic shock, and rheumatoid arthritis. A very important result is the demonstration that PLA2 is an acute phase protein, like CRP. Indeed, there is a close correlation between PLA2 mass concentration and CRP levels in several pathological conditions. Although the determination of C-reactive protein is much easier to perform and is routinely carried out in most clinical laboratories, the assessment of PLA2 activity or mass concentration has to be considered as a reliable approach to obtain a deeper understanding of some pathological conditions and may offer additional information concerning the prognosis of several disorders.

Serial changes in plasma levels of pancreatic elastase 1 after pancreatic surgeries

The alterations of the plasma level of elastase 1 (Ela) were investigated in 15 patients undergoing total pancreatectomy (TP), 18 patients undergoing pancreatoduodenectomy (PD), 8 patients undergoing distal pancreatectomy (DP) and 10 patients undergoing gastrectomy for gastric cancer (GR). The Ela level decreased rapidly below the normal level after TP. The plasma half-life of Ela was 4.6 +/- 1.2 h (Mean +/- SEM). The Ela levels after PD were abnormally elevated until the 7th postoperative day. The Ela levels after DP and GR were elevated gradually until the 7th postoperative day. From 1 to 6 months after PD, DP and GR, the Ela levels were normal. An additional release of Ela from the remaining pancreas following direct surgical interventions to the pancreas resulted in the elevated of the plasma level of Ela in the early postoperative period. The plasma level of Ela was normalized within 2 weeks after pancreatic surgery.

The reference range for complexed alpha 2-macroglobulin human plasma: development of a new enzyme linked in immunosorbent assay (ELISA) for quantitation of complexed alpha 2-macroglobulin

Purified alpha 2-macroglobulin was complexed by reaction with methylamine and used to raise monoclonal murine antibodies. A four-step enzyme linked immunosorbent assay (ELISA) was developed to determine the antibody-specificity of the produced monoclonal murine antibodies towards human native and complexed alpha 2-macroglobulin. Two monoclonal antibodies were selected, H11A11 (specific towards complexed alpha 2-macroglobulin) and 1CG4 (recognizes both forms of the molecule), and purified by affinity chromatography on protein G. The purified antibodies were used to develop a fast three-step ELISA for exact quantitation of complexed and total alpha 2-macroglobulin in human plasma. The intra-assay coefficient of variation (CV) for measurement of complexed alpha 2-macroglobulin is 2.2-9.9%, whereas the inter-assay CV was determined to be 3.7-10.5% and the recovery of the assay is 93-108%. The assay for total alpha 2-macroglobulin has an intra-assay CV of 3.0-15.5%, an interassay CV of 5.1-21.2% and a recovery of 91-116%. Citrated plasma samples from 139 healthy blood donors were examined, resulting in a reference range for complexed alpha 2-macroglobulin of 13.5-31.1 mg 1(-1) with a median value of 21.7 mg 1(-1). The concentration of total alpha 2-macroglobulin was measured by the same assay using the monoclonal antibodies 1CG4. For total alpha 2-macroglobulin we determined the reference range to be 1.12-3.54 g 1(-1) with a median value of 2.14 g 1(-1). Based on these results the reference range for complexed alpha 2-macroglobulin as a percentage of total alpha 2-macroglobulin was calculated to be 0.8-1.9% with a median value of 1.0%.

A radioimmunoassay for pancreatic elastase 1: use of alpha 1-antitrypsin-elastase 1 conjugate as both standard and tracer to eliminate the influence of anti-elastase 1 autoantibodies

We have recently reported the occurrence of anti-elastase 1 autoantibodies in human sera (Asada et al., Biochim Biophys Acta, 1991;1080:34-39). The usual radioimmunoassay of elastase 1 in autoantibody-positive sera gave abnormally high levels of elastase 1 and low recoveries of elastase 1 added to the sera. Now we have established a new radioimmunoassay system for determining pancreatic elastase 1 in serum, in which alpha 1-antitrypsin elastase 1 conjugate, the major conjugation form of elastase 1 in serum, is used as standard and alpha 1-antitrypsin-[125I]elastase 1 as tracer, because we found that the conjugate could bind to the elastase 1 specific antiserum but not to the autoantibodies. Thus the new assay system completely eliminate the unfavorable effects of the autoantibodies. The elastase 1 levels determined by the new assay method exhibited a good correlation with those obtained by a commercial assay kit in the autoantibody-negative sera, while no correlation was observed in the autoantibody-positive sera.

A prospective trial of early detection of pancreatic cancer by ultrasonographic examination combined with measurement of serum elastase 1

The accuracy of ultrasonographic examination combined with measurement of elastase 1 levels for early detection of pancreatic cancer was evaluated prospectively. Abdominal ultrasonographic examination and measurement of serum elastase 1 levels were done within 2 weeks after the initial visit to the clinic in a total of 2098 patients older than 35 years of age with symptoms suggesting pancreatic disease. Those in which one or both of these examinations had abnormal results underwent additional tests such as endoscopic retrograde cholangiopancreatography and computed tomography. Of those with pancreatosonograms with abnormal results with or without abnormally high serum elastase 1 levels, 19 patients eventually were found to have pancreatic cancer. No patients with pancreatic cancer, a normal level of serum elastase 1, and a pancreatosonogram with normal results were found, but follow-up studies revealed one pancreatic cancer in 189 patients after technically unsatisfactory ultrasonographic examination. In 9 (45%) of the 20 cases detected in this study, the pancreatic cancers were resectable, and two (10%) were less than 2.0 cm in longest diameter. These findings indicate that this combined examination is useful for early detection of pancreatic cancer. However, no pancreatic cancer was found in patients with abnormally high serum elastase 1 levels without a pancreatosonogram with abnormal results. Moreover, a combination of ultrasonographic examination and measurement of the elastase 1 level did not raise the diagnostic accuracy over that of ultrasonographic examination alone. These findings indicate that ultrasonographic examination alone is useful in screening for early pancreatic cancer.

Genomic organization of the human homologue of the rat pancreatic elastase I gene

The homologue of the rat pancreatic elastase I gene was found in the human genome, but its transcription was completely suppressed in the adult human pancreas as we reported previously. In this study, we characterized the complete structure of the eight putative exons of the silent gene for human elastase I. A genotype analysis of the exon 1 DNA sequence revealed that at least two allelic elastase I genes are present in human genomes. A primate-specific repetitive DNA element (MER1) was identified in the 3'-flanking region of the human elastase I gene. The primary structure of human preproelastase I, deduced from the sequences of the eight exons, showed an 89% identity with that of porcine or rat pancreatic preproelastase I. The amino acid residues of the serine protease catalytic triad and the eight cysteine residues conserved in the elastase family were present at positions equivalent to those observed in porcine and rat elastase I, suggesting that the gene product may function as an elastolytic enzyme if this gene is expressed in any tissue.

Characterization of metalloelastase-like activity from the plasma of a patient with Tangier disease

An enzymatic activity with releases p-nitroaniline from 3-carboxypropionyl-trialanine p-nitroanilide (Suc[Ala]3NA) was characterized in blood plasma of patients with Tangier disease. This activity results from the sequential action of a metalloendopeptidase (MP) and an aminopeptidase (AP). These proteases were purified 134- (MP) and 82-fold (AP) from low density and very low density lipoproteins (LDL and VLDL) depleted Tangier plasma by DEAE-Trisacryl chromatography and gel filtration. MP and AP could be separated by polyacrylamide gel electrophoresis. MP shares some analogy with neutral endopeptidase (membrane metalloendopeptidase, EC 3.4.24.11) and is able to degrade human plasma fibronectin (mainly to fragments of 185, 168 and 128 kDa) as evidenced on Western blots. It cannot hydrolyse 3H-labelled insoluble elastin and apolipoprotein AII, but did cleave a dinitrophenyl-octapeptide as well as apolipoprotein AI to 25-kDa and 24-kDa fragments formed sequentially. It may therefore be partially responsible for the in vivo degradation of apoAI observed in Tangier disease.

Inactivation of human gamma interferon by Pseudomonas aeruginosa proteases: elastase augments the effects of alkaline protease despite the presence of alpha 2-macroglobulin

Pseudomonas aeruginosa alkaline protease (AP) has recently been shown to produce limited proteolysis of human gamma interferon (IFN-gamma) and thereby destroy the antiviral and macrophage-activating activities of the lymphokine. In the present study we describe some of the characteristics of Pseudomonas elastase (E) with regard to inactivation of human IFN-gamma. The inhibitory effect of E on IFN-gamma bioactivity differed from that of AP in that the direct effects of E were reduced in the presence of human serum. That this property of human serum was in large part attributable to the protease inhibitor alpha 2-macroglobulin (alpha 2-M) was suggested by the following observations: (i) methylamine treatment of serum reduced its effect on E, (ii) E interacted directly with alpha 2-M to induce a characteristic conformational change in the protease inhibitor, and (iii) preformed E-alpha 2-M complexes lacked IFN-gamma-degrading activity. Despite these findings, anti-E antiserum partially neutralized the effect that a Pseudomonas filtrate showed on IFN-gamma, suggesting that E contributes to the activity of bacterial filtrates. Treatment of IFN-gamma with E in the presence of a suboptimal concentration of AP resulted in an E dose-dependent inactivation of the lymphokine. Preformed E-alpha 2-M complexes, although ineffective by themselves at cleaving IFN-gamma, degraded the lymphokine, providing AP was also present in the reaction mixture. These data demonstrate that the destruction of small, biologically significant peptides by Pseudomonas proteases can involve protease-protease synergy that acts even in the presence of the serum protease inhibitor alpha 2-M.

Role of serum pancreatic enzyme assays in diagnosis of pancreatic disease

The serum behavior of amylase, pancreatic isoamylase, lipase, trypsinogen, and elastase 1 was studied in 145 patients with pancreatic disease and in 66 patients with abdominal pain of nonpancreatic origin, for the purpose of evaluating the relative diagnostic utility of their assays. In 34 patients with acute pancreatitis, serum lipase, trypsinogen, and elastase 1 were elevated in all 34, pancreatic isoamylase in 33 (97%) and amylase in 30 (88%). Ten of these acute pancreatitis patients were followed sequentially for seven days: the variations in their serum enzyme levels were parallel, although the lipase, trypsinogen, and particularly the elastase 1 elevations persisted longer than did those of amylase and pancreatic isoamylase. Among the patients with chronic pancreatitis, either in painful relapse (N = 19) or with pancreatic cysts (N = 15), the respective percentages of enzymes elevations were: 79 and 80% for elastase 1, 68 and 67% for trypsinogen, 63 and 73% for pancreatic isoamylase, 58 and 60% for lipase, 53 and 60% for amylase. In the 52 chronic pancreatitis patients studied during clinical remission, serum enzyme behavior varied greatly, and a majority of the assays (60%) were normal; even in the case of severe pancreatic exocrine insufficiency, normal as well as abnormally high and low enzyme values were seen. Highly variable enzyme behavior was also seen in the 40 patients with pancreatic cancer, and elastase I was the most frequently (35%) elevated enzyme in this group as well. Among the patients with abdominal pain of nonpancreatic origin, abnormally high enzyme levels were present in percentages ranging from 6% for lipase to 21% for trypsinogen.(ABSTRACT TRUNCATED AT 250 WORDS)

Serum elastase 1 in inflammatory pancreatic and gastrointestinal diseases and in renal insufficiency. A comparison with other serum pancreatic enzymes

Serum elastase 1 has been evaluated in 115 patients with pancreatic and nonpancreatic gastrointestinal diseases and in 36 healthy controls. Increased serum elastase 1 values were found in all 27 patients with acute pancreatitis. If the diagnostic cutoff was established as the 2-fold increase above the upper normal range, sensitivity of elastase 1 (100%) was superior to pancreatic lipase (90%), immunoreactive trypsin (87%) and pancreatic amylase (78%). Specificity was 96% for elastase 1 at this cutoff. No distinction was possible between edematous and necrotizing acute pancreatitis on the basis of peak serum elastase 1 concentrations. Among 32 patients with chronic pancreatitis increased serum elastase 1 values were found in 22% and decreased values in 16% of patients, showing a striking parallelism to serum values of pancreatic lipase and immunoreactive trypsin. Specificity, established in controls and 49 patients with different gastrointestinal diseases, was 77% for elastase 1, 76% for immunoreactive trypsin, 83% for pancreatic lipase and 91% for pancreatic amylase. In addition, we investigated 21 patients with severe chronic renal diseases. In patients with renal insufficiency elastase was increased in 33%, comparable to the frequency of increased amylase and pancreatic amylase serum levels, whereas immunoreactive trypsin was increased in 95%. Immunoreactive trypsin showed a significant correlation to creatinin serum concentration, whereas the other enzymes did not.

Raised serum concentrations of pancreatic enzymes in cigarette smokers

Circulating concentrations of digestive enzymes, certain lysosomal hydrolases and protease inhibitors were measured in 19 heavy smokers and 13 non-smokers before (basal) and at 15, 30, and 60 minutes after a single intravenous injection of secretin (75 CU). In smokers, basal serum amylase and immunoreactive pancreatic elastase 2 (IRE2) concentrations were about 100% and 25% higher respectively, than in the non-smokers, whereas, no differences were observed in basal immunoreactive cationic trypsinogen (IRCT) concentrations and in acid phosphatase and beta-glucuronidase activities between the two groups. Furthermore, a single injection of secretin to cigarette smokers significantly increased serum amylase, IRCT and IRE2 by 155%, 200%, and 100%, respectively when compared with their corresponding basal levels. No such increment was observed in the non-smokers. In addition, there were no significant differences in serum trypsin or elastase inhibitory capacity or immunoreactive alpha 1-protease inhibitor and alpha 2-macroglobulin levels between smokers and non-smokers. The levels and inhibitory capacity of these protease inhibitors was also not affected by secretin injection. These data suggest that cigarette smoking enhances the responsiveness of the exocrine pancreas to a physiological stimulus such as secretin, with resultant substantial increase in the concentrations of pancreatic hydrolases in blood.

The effect of elastase on chickens with endogenous hyperlipidemia

Elastase has been reported to have a multiplicity of activities which may be protective against atherosclerosis. The data reported here support those reports and show a clear antiatherosclerotic effect in hyperlipidemic chickens. We have shown here that a reduction in calcium and lipid accumulation in aortic tissue and possibly a plasma cholesterol lowering effect can be seen in the chicken when treated with elastase. The most important effect in this animal is probably to aid removal of lipid bound to elastin in the intima. This was achieved at a dose of only 600 U elastase while reductions in tissue calcium required 1800 U elastase.

Diagnostic value of serum elastase 1 in pancreatic disease

We studied serum elastase 1 concentrations in patients with pancreatic disease to assess its diagnostic value and compare its sensitivity and specificity with that of amylase and pancreatic isoamylase. Markedly raised concentrations of elastase 1 were found in all twenty-nine patients with acute pancreatitis (amylase was elevated in all but three and pancreatic isoamylase in all but one). Serial measurements of the three enzymes in acute pancreatitis showed that elastase remained elevated longer than amylase and pancreatic isoamylase. The majority of chronic pancreatitis patients studied during a painful relapse (16 out of 21, 76 per cent) had elastase concentrations above the upper normal limit. Amylase and pancreatic isoamylase were elevated in 11 (52 per cent) and in 13 (62 per cent), respectively. Most patients with chronic pancreatitis studied during clinical remission (39 out of 43) had serum elastase levels either within (n = 24) or below (n = 15) the control range. The latter had severe exocrine pancreatic insufficiency and steatorrhoea. In carcinoma of the pancrease, 20 out of 32 (63 per cent) had abnormal serum elastase concentrations; 16 were higher and 4 lower than the control range. Amylase was abnormal in 10 (31 per cent) (8 high, 2 low), and pancreatic isoamylase was abnormal in 16 (50 per cent) (11 high, 5 low). In 46 control patients with non-pancreatic abdominal pain, serum elastase concentrations were not significantly different from those in healthy controls. Elastase was slightly raised in two, whereas amylase and pancreatic isoamylase were elevated in seven and eight, respectively. We conclude that serum elastase 1 is a highly sensitive and specific indicator of pancreatic disease.

Serum immunoreactive elastase in diagnosis of pancreatic diseases. A sensitive marker for pancreatic cancer

Diagnostic significance of serum immunoreactive elastase-1 was studied in 137 patients with pancreatic disease, 335 with various nonpancreatic diseases, and 416 healthy controls by using radioimmunoassay. Frequency of abnormally high serum elastase values exceeding 410 ng/dl was 100% in acute pancreatitis (N = 14), 40% in chronic pancreatitis (N = 80), and 72% in pancreatic cancer (N = 43). In pancreatic cancer the mean value of serum elastase in resectable cancer (N = 19) was significantly higher than that in unresectable cancer (N = 24). Sensitivity, specificity, and efficiency of serum elastase in pancreatic cancer were 72.1%, 98.3%, and 95.9% against healthy controls; 72.1%, 85.9%, and 83.6% against nonpancreatic digestive diseases; and 72.1%, 60.0%, and 64.2% against chronic pancreatitis at a cutoff level of 410 ng/dl, respectively. High serum elastase could be a diagnostic clue to detect pancreatic duct obstruction due to pancreatic cancer, although further examination should be done by endoscopic retrograde pancreatography and other imaging studies.

"In vivo" and "in vitro" inhibition of human pancreatic chymotrypsin A by serum inhibitors

The interaction of human pancreatic chymotrypsin A with serum inhibitors was assessed by enzyme immunoassay, enzymatic activity and inhibitory capacity measurements and electrophoretic analyses. In normal serum, chymotrypsin A was detected in four forms: one form (Mr approximately equal to 25,000) which might be chymotrypsinogen A and three forms complexed to the main inhibitors present in serum, alpha 2-macroglobulin (alpha 2-M), alpha 1-proteinase inhibitor (alpha 1-PI) and alpha 1-antichymotrypsin (alpha 1-Achy). As chymotrypsin A remains to 90% active when bound to alpha 2-M, the chymotrypsin A/alpha 2-M complex was quantified by an enzymatic assay. The kinetic parameters of the interaction of chymotrypsin A with alpha 1-PI and alpha 1-Achy were determined. Using these data the partition of chymotrypsin A between the different inhibitors in serum was calculated. In acute pancreatitis, the chymotrypsin A plasma level follows the progression of the disease and in this case as well as in normal serum alpha 1-PI is the major antagonist of chymotrypsin A.

Binding sites for elastase on cultured human fibroblasts that do not mediate internalization

The proteolytic actions of elastases have been implicated in extracellular matrix damage, which is characteristic of a variety of pathological conditions including emphysema and rheumatoid arthritis. In order to elucidate the molecular events involved in elastase interaction with connective tissue cells, the present study was designed to investigate the association of elastase with human fibroblasts at 4 degrees C. Elastase bound saturably to binding sites that were present on the surface of these cells. Analysis of cell-bound elastase by sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed the presence of a high molecular weight complex (Mr 54,000) that was not formed with elastase whose catalytic site serine was derivatized with a diisopropylphosphate group. The complex did not represent elastase bound to either protease nexin or contaminating serum. The cellular component with which elastase formed a complex could not be detected in the cell culture medium. Unexpectedly, elastase that had been pre-bound at 4 degrees C was not internalized after cells were warmed to 37 degrees C. The elastase binding site described in this report is therefore distinct from high affinity binding sites involved in receptor-mediated endocytosis and intracellular degradation.

Serum immunoreactive cationic trypsinogen: a useful indicator of severe exocrine dysfunction in the paediatric patient without cystic fibrosis

We evaluated serum cationic trypsinogen as a marker of exocrine pancreatic function in children without cystic fibrosis. The ability of this test to determine steatorrhoea of pancreatic origin, and its relationship to a wide range of exocrine pancreatic function were assessed. Serum trypsinogen was measured in 32 children with steatorrhoea, 10 with pancreatic and 22 with non-pancreatic causes. In patients with pancreatic steatorrhoea, serum cationic trypsinogen was 4.9 +/- 4.9 micrograms/l (mean +/- SD), significantly below values in patients with non-pancreatic steatorrhoea (47.0 +/- 22.1 micrograms/l, p less than 0.001) and 50 control subjects (31.4 +/- 7.4 micrograms/l, p less than 0.001). Serum cationic trypsinogen values in patients with pancreatic steatorrhoea all fell below the lower limit of our control range and below all values for patients with non-pancreatic steatorrhoea. Serum cationic trypsinogen was also evaluated against pancreatic trypsin output in 47 patients (range 0.2-17.0 yr who underwent a hormonal pancreatic stimulation test. In 17 patients, serum cationic trypsinogen was low (less than -2SD or less than 16.6 micrograms/l), and associated with greatly impaired pancreatic trypsin output, ranging from 0-8% of mean normal trypsin output. Five of these 17 patients did not have steatorrhoea. In 30 patients with normal or raised serum cationic trypsinogen (greater than or equal to 16.6 micrograms/l), pancreatic trypsin output ranged from 15-183% of mean normal values. In conclusion, low serum cationic trypsinogen suggests severely impaired exocrine pancreatic function, with sensitivity extending above the steatorrhoeic threshold. In the presence of steatorrhoea, low serum cationic trypsinogen indicates a pancreatic aetiology. Normal serum cationic trypsinogen, however, does not exclude impaired pancreatic function, above the steatorrhoeic threshold.

Serum elastase 1 in chronic pancreatic disease

Elastase 1 and immunoreactive trypsin were assessed by a RIA technique in the sera of 29 control subjects, 24 pancreatic cancer patients, 22 patients with chronic pancreatitis and 31 with extra-pancreatic diseases to ascertain and compare their usefulness in chronic pancreatic disease diagnosis. Increased levels of elastase 1 were detected in 60.9% of pancreatic cancer and in 61.1% of chronic pancreatitis patients; low values were found in only two subjects with pancreatic disease. A close correlation between the two enzymes was found in patients suffering from pancreatic cancer and chronic pancreatitis. These data suggest that serum elastase 1, as well as immunoreactive trypsin, is of limited value in chronic pancreatic disease diagnosis; increased levels of the two enzymes always occur simultaneously; low immunoreactive trypsin values together with normal elastase 1 serum levels are detectable in a number of patients with chronic pancreatitis and severe exocrine insufficiency.

Studies on the elastolytic activity of chymotrypsin

Chymotrypsin can completely solubilize insoluble [3H]-labeled ligamentum nuchae elastin. At similar enzyme levels, trypsin solubilizes only 5% of the elastin substrate whereas pancreatic elastase completely solubilizes the elastin at one-tenth the concentration required for chymotrypsin solubilization. The elastolytic activity of chymotrypsin is dependent on Ca+2, is enhanced by SDS, and is inhibited by NaCl at concentrations above 10 mM. The elastolytic activity of chymotrypsin is also inhibited by TPCK, a chymotrypsin specific inhibitor, but not by TLCK, a trypsin specific inhibitor. Neither TPCK nor TLCK abolish the elastolytic activity of pancreatic elastase. The sizes of [3H]elastin fragments produced by the elastolytic activity of chymotrypsin are similar to those produced by pancreatic elastase, and larger than those produced by trypsin.

Interaction of human plasmin with human alpha 2-macroglobulin

The steady-state kinetic parameters of plasmin and the alpha 2-macroglobulin (alpha 2M)-plasmin complex toward the chromogenic substrate Val-Leu-Lys-p-nitroanilide (S-2251), in the presence and absence of plasmin competitive inhibitors, have been determined. At pH 7.4 and 22 degrees C, the Km values for plasmin and alpha 2M-plasmin for S-2251 were 0.13 +/- 0.02 mM and 0.3 +/- 0.03 mM. The kcat of this reaction, when catalyzed by alpha 2M-plasmin, was 6.0 +/- 0.5 s-1, a value significantly decreased from the kcat of 11.0 +/- 1.0 s-1, determined when free plasmin was the enzyme. KI values for benzamidine of 0.50 +/- 0.05 mM and 0.23 +/- 0.02 mM were obtained for S-2251 hydrolysis, as catalyzed by alpha 2M-plasmin and plasmin, respectively. When leupeptin was the competitive inhibitor, KI values of 5.0 +/- 0.65 microM and 1.0 +/- 0.1 microM were obtained when alpha 2M-plasmin and plasmin, respectively, were the enzymes employed for catalysis of S-2251 hydrolysis. The comparative rates of reaction of the peptide inhibitor Trasylol (Kunitz basic pancreatic inhibitor) with plasmin and alpha 2M-plasmin were also determined. A concentration of Trasylol of at least 3 orders of magnitude greater for alpha 2M-plasmin than for free plasmin was required to observe inhibition rates on comparable time scales.(ABSTRACT TRUNCATED AT 250 WORDS)

Alcohol and the respiratory tract

Possible mechanisms by which alcohol may adversely affect the respiratory system are considered. Alcohol ingestion impairs glottic reflexes, and alcoholics are predisposed to pneumonias and lung abscesses from aspiration of oropharyngeal bacteria. Alcohol intoxication also increases the frequency of sleep apnea and may result in respiratory failure from oversedation.

Elastolysis of insoluble elastin

We developed an assay for measurement of elastolytic activity using insoluble 3H-labelled particulate elastin adherent to plastic that is capable of detecting 150 picograms of pancreatic elastase. This equals or exceeds the sensitivity of the most sensitive previously reported systems, without requiring sodium dodecyl sulfate treatment of the elastin. Elastin digestion is dependent upon substrate and elastase concentration, but is not linearly related to time. This is partially attributable to elastase denaturation or autolysis under the assay conditions. The assay could easily detect elastase secreted by either peritoneal or alveolar macrophages. Compared to previously described assays using substrates that closely resemble the physiologic substrate, this represents a considerable increase of sensitivity of detection of elastolytic activity of enzymes.

Serum proteolytic and antiproteolytic activity in acute pancreatitis

This study has demonstrated an imbalance between the blood proteolytic and antiproteolytic system in acute pancreatitis. Serum elastase activity is markedly increased and elastase inhibitory capacity is decreased in this disease as compared with those in chronic pancreatitis and the control values. We have found that a return to normal values represents better evidence of resolution than amylase determinations. These results offer the clinician a biochemical guideline for the medical management of acute pancreatitis.

A probe of the human plasmin-alpha 2-macroglobulin interaction utilizing monoclonal antibodies to human plasmin

These experiments have shown that alpha 2M may have a bait region capable of accommodating proteases of a far greater molecular weight than previously recognized, since antibody-plasmin complexes apparently become entrapped. In the case of large proteases, however, it now appears that a portion of these molecules is not enclosed. Clearly, in the case of plasmin, the K1-4 region remains outside the molecular trap.

Dissociability of enzyme-alpha 2-macroglobulin complexes

Experiments were performed to measure the extent to which enzymes bound to alpha 2-macroglobulin (alpha 2M) could be dissociated from the complex. Noncovalent complexes are known to exist between alpha 2M and proteases, such as methyl-trypsin that have had their lysyl amino covalently blocked. Complexes between the inhibitor and native enzymes also have a certain fraction noncovalent binding. Because of the severe steric hindrance imposed on enzymes bound to alpha 2M, even in the noncovalent mode, it has been proposed in the literature that they are not dissociable in the usual sense but, rather, are "trapped" in clathrate-like complexes. The results presented here show that lysyl-blocked methyl-thrombin, or native thrombin are released from their alpha 2M complex by an excess of other lysyl-blocked or native proteases. Under conditions where native thrombin is displaced, labeled enzymes can be incorporated, indicating the inhibitor is intact by the criterion of incorporating enzymes. Likewise, native elastase can be released from its alpha 2M complex by excess cold elastase or the inactive anhydrotrypsin, the latter experiment being carried out with an excess of the low-molecular-weight inhibitor diisopropyl phosphofluoridate. In conjunction with previous results showing that lysyl-blocked enzymes are removed from alpha 2M by soybean trypsin inhibitor, the data indicate that, however sterically hindered, alpha 2M-bound enzymes are dissociable and no unique "trapped" intermediate need be postulated.

Diagnostic significance of immunological assay of pancreatic elastases in acute pancreatitis

Pancreatic elastases have been assumed to be implicated in the pathogenesis of the vascular injury in acute hemorrhagic pancreatitis. We reported the purification and some properties of human pancreatic elastases. In the present study, the value of the determination of serum pancreatic elastases was investigated. 39 patients with acute hemorrhagic and acute edematous pancreatitis were studied. Serum elastase 1(E-1) and elastase 2(E-2) were measured by radioimmunoassay recently developed in our laboratory. The molecular form of exogenous and endogenous elastases in serum was studied by gel filtration on Sephadex G-200. The mean and standard deviation of serum pancreatic E-1 and E-2 were 1.49 +/- 0.49 ng/ml and 292 +/- 82 ng/ml, respectively. In acute pancreatitis, both E-1 and E-2 had markedly raised serum concentrations. However, no significant difference was observed between acute hemorrhagic and acute edematous pancreatitis. Endogenous immunoreactive E-1 and E-2 were present in serum in complex form with alpha 1-antitrypsin. In contrast, exogenous elastases were bound to alpha 1-antitrypsin and alpha 2-macroglobulin.

Clinical usefulness and methodology of immunological assay of pancreatic enzymes

Radioimmunoassays for plasma pancreatic enzymes, especially cationic trypsin, are good tools to diagnose pancreatic pathology. The trypsin assay is very sensitive. Its detection limit is 300 pg/ml. The plasma level of this enzyme appears to be representative of pancreatic function. This assay was shown to be valuable in the diagnosis of acute pancreatitis, and to follow the course of the disease. In chronic pancreatitis, it enables assessment of residual function of the organ. In the terminal stage of this disease, very low values were found. Used as a screening test, the assay allowed early detection of cystic fibrosis.

In vitro interaction of porcine serum and colostrum protease inhibitors with pancreatic trypsin, chymotrypsin and elastase

The partition of 125I-labelled pancreatic trypsin, chymotrypsin and elastase between the inhibitors, alpha 2-macroglobulin f and s, alpha 1-protease inhibitor, alpha 2-antitrypsin, inter-alpha-trypsin inhibitor and the specific sow colostrum protease inhibitor, was studied in vitro by gradually increasing the concentration of these proteases in blood serum from adult and newborn pigs. As revealed by immunoelectrophoresis in combination with autoradiography, differences were noted in the abilities of the various protease inhibitors to interact with and to form complexes with the three proteases, resulting in changes in location, height and numbers of precipitates. Among the serum inhibitors, alpha 2-macroglobulins showed the highest relative affinity to all three proteases, while alpha 1-protease inhibitor showed a high relative affinity only for chymotrypsin. Serum alpha 2-antitrypsin complexed only with trypsin, with a low relative affinity. alpha 2-Antitrypsin also interacted with chymotrypsin and elastase, but without forming complexes. When complexes of sow colostrum protease inhibitor and trypsin were added to the serum from neonatal pigs, these complexes remained stable. The results obtained from these in vitro studies, indicating differences in the relative affinities of the inhibitors to the various proteases, give some information about the role of the inhibitors in vivo, both in adult and in neonatal pigs.

Serum elastase I levels in pancreatic disease

The radioimmunoassay for human elastase I used in this study is accurate, sensitive, and specific, which we have confirmed. The assay can be done within 4 hours, which is important for clinical purposes. A total o 103 subjects were examined, and levels of 99 to 370 ng/dl (mean 200) in normal human sera were determined. The serum elastase levels in acute, acute relapsing, and chronic relapsing pancreatitis were significantly higher than normal. Although serial determinations returned to normal within 5 days after the onset of the attack, they decreased gradually and remained high on the 7th, 10th, and 11th days in patients who still had residual signs of pancreatitis. The values in patients with chronic pancreatitis and various other diseases were normal. The values in patients with acute pancreatitis were significantly higher than in those with hyperamylasemia of nonpancreatic origin. Twelve of 19 patients with pancreatic cancer had abnormal serum elastase levels; this was especially true in patients with cancer of the pancreatic head. We believe that the measurement of serum elastase levels by radioimmunoassay will become a useful diagnostic method for pancreatic disease in the future.

Origin of circulating serum immunoreactive trypsin in man

Serum trypsin concentrations within the portal venous system have been measured in man during transhepatic portal venography in an attempt to determine its source. In eight experiments, mean serum trypsin concentration at the splenic hilum was 180 +/- 25 ng/ml (mean +/- SEM). Trypsin concentration in the rest of the splenic vein was not significantly different. The mean concentrations in the portal vein (210 +/- 32 ng/ml) and within the superior mesenteric vein (233 +/-- 29 ng/ml) were, however, significantly higher than at the hilum (P less than 0.05). Following cholecystokinin-pancreozymin (CCK-PZ) and secretin stimulation, marked increases in serum trypsin concentration were seen within the portal vein (two patients) and deep within the superior mesenteric (two out of three patients). We conclude that circulating serum trypsin is derived, at least in part, from intestinal reabsorption.

The fate of intravenously injected trypsinogens in dogs

After intravenous injection of autologous purified and radiolabeled anionic and cationic trypsinogens in the dog, there is a multiexponential elimination from serum of the trypsinogens without activation to active trypsins. The results are in agreement with an elimination of the trypsinogens iva glomerular filtration, a variable tubular uptake of anionic trypsinogen, and a complete tubular uptake of cationic trypsinogen. Fractional catabolic rates for anionic trypsinogen were 0.35-0.92 h-1 and for cationic trypsinogen 0.38-1.05 h-1. The total amount of anionic trypsinogen turned over in the circulation is estimated at approximately 0.55 mg every 24 h, and the corresponding figure for cationic trypsinogen is 0.35 mg/24 h.

Isolation and characterization of native single-chain porcine pancreatic kallikrein, another possible precursor of urinary kallikrein

Porcine pancreatic kallikrein B' was isolated from partially purified prokallikrein B activated "spontaneously" (most probably due to the action of some contaminating proteinase). Upon dodecyl sulfate electrophoresis after reduction, the enzyme migrated like the single-chain alpha-kallikreins A from submandibular glands and urine of the pig, indicating an apparent molecular weight of about 36,000. Evidently, porcine pancreatic kallikrein B' is also a single-chain alpha-kallikrein, in contrast to the two-chain beta-kallikrein obtained by the usual isolation procedure from autolyzed porcine pancreas. The amino acid composition of kallikrein B' is very similar to that of the other porcine glandular kallikreins and it too contains glucosamine. The specific activities of kallikrein B', as measured under various conditions, also resemble closely those of porcine urinary and submandibular kallikreins, as do the rates of the enzyme-catalyzed hydrolyses of various amino acid ester substrates. During the hydrolysis of Bz-LysOMe or low concentrations of Bz-ArgOEt, the same strange biphasic course of the reaction is seen, as observed previously in the case of the other single-chain porcine kallikreins. Consequently, the properties of native porcine pancreatic kallikrein are well consistent with the suggestion that urinary kallikrein represents filtered enzyme of pancreatic and submandibular origin. Further available evidence for this and the alternative hypothesis of synthesis of urinary kallikrein in the kidney is discussed.

"Tryptic-like" activity in sera of patients with pancreatitis

Serum trypsin esterolytic activity was measured in 106 sera from 61 controls and 45 patients with pancreatitis. A trypsin specific synthetic substrate, N-alpha-benzoyl-L-arginine-paranitroanilide, was used. High levels of enzymatically active trypsin were shown to be present in serum of patients with pancreatitis. No difference between the two samples was noticed for the serum concentrations of alpha-1-antitrypsin and alpha-2-macroglobulin (the two main serum trypsin inhibitors). Active trypsin was contained in the high molecular weight fraction of plasma proteins, corresponding to a complex with alpha-2-macroglobulin. The determination of serum typsin activity as a sensitive test for detection of pancreatitis was demonstrated to be statistically significant.

Elastinolytic activity in the rat aortic smooth muscle cells in culture

Elastinolytic activity was examined in cultured rat aortic smooth muscle cells, using Congo Red elastin as a substrate. Elastinolytic activity was demonstrated in the soluble fraction of sonicated smooth muscle cells, with an optimal pH around 10.0. The soluble fraction also showed elastase-like esterolytic activity against the synthetic substrate, N-succinyl-trialanyl-paranitroanilide.

Human pancreatic proelastase 2. Sequence of the activation peptide

The N-terminal sixteen residues of the amino acid sequence of reduced and alkylated human pancreatic proelastase 2 have been established, and N-terminal amino acid residue has been shown to be carboxymethylcysteine. A peptide containing an amino acid sequence corresponding to the first twelve residues of proelastase 2 was isolated following activation of proelastase 2 with trypsin, performic acid oxidation, and gel filtration. This peptide was not released prior to performic acid oxidation, suggesting that it remains attached to the major peptide chain via a disulfide bond containing the N-terminal half-cysteine in a manner similar to that found for chymotrypsinogens. However, the amino acid sequence of the activation peptide is not strongly homologous to either porcine chymotrypsinogen A or porcine proelastase 1.

Studies on immunoreactive pancreatic elastase 2 in human serum

A radioimmunoassay for human pancreatic elastase 2 is described. DFP-Inactivated pancreatic elastase 2 is used both as standard and tracer. The concentration in normal human plasma is approximately 60 micrograms immunoreactive pancreatic elastase 2, which rises in acute pancreatitis. Pancreatic elastase 2 appears in plasma in a form with a molecular size exceeding that of the proenzyme. In vitro studies demonstrate that a complex between pancreatic elastase 2 and alpha 1-antitrypsin arises after incubation of a mixture of pancreatic juice and plasma. The results presented support the conclusion that proelastase is bound by alpha 1-antitrypsin after the discharge from the pancreatic gland to the extracellular tissue fluids around the gland.

Radioimmunoassay for human pancreatic secretory trypsin inhibitor: measurement of serum pancreatic secretory trypsin inhibitor in normal subjects and subjects with pancreatic diseases

A reliable radioimmunoassay (RIA) for human pancreatic secretory trypsin inhibitor (PSTI) has been developed. The method is highly sensitive (0.4 ng/ml), reproducible and specific. A good parallel relationship was observed between the standard curve and dilution curves for serum and urine. The PSTI bound to trypsin-alpha 2-macroglobulin complexes was found not to be immunoreactive, whereas a part of the psti-trypsin complex was immuno-reactive. In healthy individuals, serum PSTI level ranged from 5.4 ng/ml to 16.0 ng/ml, the average being 11.3 ng/ml (S.D. +/- 2.7). Elevated values were observed in patients with acute pancreatitis (highest value 3200 ng/ml), and in some patients with chronic relapsing pancreatitis.