Isoforms of procarboxypeptidase B, (pancreas-specific protein, PASP) in human serum, pancreatic tissue and juice

Impact of high dietary zinc on zinc accumulation, enzyme activity and proteomic profiles in the pancreas of piglets

The exocrine pancreas plays an important role in zinc homeostasis. Feeding very high (2000-3000mgzinc/kg diet) levels of zinc oxide to piglets for short periods is a common practice in the swine industry to improve performance and prevent diseases. The impact on pancreatic function and possible side effects during long-term feeding of high dietary zinc levels are still poorly understood. A total of 54 weaned piglets were either fed with low (57mg/kg, LZn), normal (164mg/kg, NZn) or high (2425mg/kg, HZn) zinc concentration in the diets. After 4 weeks of feeding, ten piglets per treatment were euthanized and pancreas samples were taken. Tissue zinc concentration and metallothionein abundance was greater with HZn compared with NZn and LZn (P<0.05). Similarly, activity of α-amylase, lipase, trypsin and chymotrypsin was higher with HZn as compared with NZn and LZn diets (P<0.05), whereas elastase activity was unchanged. Total trolox equivalent antioxidative capacity of pancreas tissue was higher with HZn diets compared with the other treatments (P<0.05). Pancreatic protein profiles of NZn and HZn fed piglets were obtained by 2D-DIGE technique and revealed 15 differentially expressed proteins out of 2100 detected spots (P<0.05). The differentially expressed proteins aldose reductase, eukaryotic elongation factor II and peroxiredoxin III were confirmed by immunoblotting. Identified proteins include zinc finger-containing transcription factors and proteins mainly associated with oxidative stress response and signal transduction in HZn compared with NZn pigs. Histologic examination however showed no morphologic changes. The results suggest that long-term supply of very high dietary zinc increases zinc and metallothionein concentration, and digestive enzyme activity, but also triggers oxidative stress reactions in the pancreas of young pigs. The data provide new insights into pancreatic function under outbalanced zinc homeostasis.

Bioinformatic identification of proteins with tissue-specific expression for biomarker discovery

BACKGROUND

There is an important need for the identification of novel serological biomarkers for the early detection of cancer. Current biomarkers suffer from a lack of tissue specificity, rendering them vulnerable to non-disease-specific increases. The present study details a strategy to rapidly identify tissue-specific proteins using bioinformatics.

METHODS

Previous studies have focused on either gene or protein expression databases for the identification of candidates. We developed a strategy that mines six publicly available gene and protein databases for tissue-specific proteins, selects proteins likely to enter the circulation, and integrates proteomic datasets enriched for the cancer secretome to prioritize candidates for further verification and validation studies.

RESULTS

Using colon, lung, pancreatic and prostate cancer as case examples, we identified 48 candidate tissue-specific biomarkers, of which 14 have been previously studied as biomarkers of cancer or benign disease. Twenty-six candidate biomarkers for these four cancer types are proposed.

CONCLUSIONS

We present a novel strategy using bioinformatics to identify tissue-specific proteins that are potential cancer serum biomarkers. Investigation of the 26 candidates in disease states of the organs is warranted.

Active carboxypeptidase B is present in free form in serum from patients with acute pancreatitis

BACKGROUND

Active carboxypeptidase B (aCAP) is the main product of activation of procarboxypeptidase. The other product derived from procarboxypeptidase B (proCAP), the activation peptide carboxypeptidase B (CAPAP), has been shown to be a marker for severity in acute pancreatitis. There have been relatively few studies dealing with the role of this enzyme in acute pancreatitis.

METHODS

A double-antibody ELISA for immunoreactive aCAP (ir-aCAP) was developed, and ir-aCAP was determined in the serum of patients with acute pancreatitis and characterized using gel filtration.

RESULTS

Serum from healthy individuals contained minimal levels of ir-aCAP, while serum from 25 patients with acute pancreatitis contained between 0.6 and 158 nmol/l. Gel filtration of serum samples from patients with acute pancreatitis showed the presence of two peaks of ir-aCAP, one corresponding to the molecular size of the free active enzyme and one corresponding to cross-reactive proCAP. When pure aCAP was mixed with serum in vitro, all ir-aCAP was recovered as one peak of free enzyme. No immunoreactivity disappeared or changed in molecular size, as might be expected if the active enzyme was bound to an inhibitor.

CONCLUSION

aCAP is present in free form in the circulation of patients with acute pancreatitis.

Complement factors in adult peripheral nerve: a potential role in energy metabolism

Complement cascade factors are known to play a critical role in myelin clearance after peripheral nerve injury. Here we show that components of both the classical (C1qa, C1qb, C1qc, C2 and C4) and alternative (C3, B and adipsin) pathways are expressed by uninjured peripheral nerve as well. mRNAs of components of the alternative pathway were predominantly found in the peri/epineurium, although factor C3 and factor B were also detected in the endoneurial compartment of adult nerve. Interestingly, adipsin mRNA was detected only in peri/epineurium, while adipsin protein was present in both peri/epineurium and endoneurium. This suggests that adipsin is transported to the endoneurium via the circulation from the peri/epineurium or outside of the nerve. Factor 5 and factor 9, necessary for the formation of the membrane-attack complex, were not detected in any part of the healthy peripheral nerve, which together with the observed presence of negative regulators of complement activation, is likely to prevent damage to the healthy nerve caused by complement activation. By analogy with the known role of complement factors in fat, we propose that local expression of these factors plays a role in the regulation of fatty acid homeostasis in the nerve and, thereby, in energy metabolism cross-talk between different compartments of the peripheral nerve.

What is the best biochemical test to diagnose acute pancreatitis? A prospective clinical study

OBJECTIVE

To determine which biochemical test is best to distinguish acute pancreatitis from other pancreatic and nonpancreatic diseases associated with hyperamylasemia.

DESIGN

We conducted a prospective clinical study of 836 consecutive patients who had a total serum amylase test requested by a physician during a 7-month period.

MATERIAL AND METHODS

Radioimmunoassay and enzymatic activity methods were used to measure pancreas-specific proteins of varied size, charge, and stability. In addition, scoring systems were used for the diagnosis of pancreatitis, and statistical analyses were done to determine sensitivity and specificity.

RESULTS

We found minor differences in sensitivity and specificity for diagnosis of acute pancreatitis among pancreatic isoamylase, phospholipase A2, colipase, lipase, and carboxylester lipase. Of these tests, the combination of isoamylase and phospholipase A2 had a small but statistically significant increased sensitivity (90%; 95% confidence interval [CI] = 74 to 98%) and specificity (93%; 95% CI = 91 to 95%) over isoamylase (90% and 92%, respectively; 95% CI = 90 to 94%) and phospholipase A2 (90% and 75%, respectively; 95% CI = 72 to 78%) alone for the diagnosis of acute pancreatitis.

CONCLUSION

Pancreas-specific proteins are satisfactory for diagnosing acute pancreatitis if the test is validated by the laboratory. Clinically, the slight advantage of using both isoamylase and phospholipase A2 does not outweigh the expense of performing two assays; we recommend using isoamylase to diagnose acute pancreatitis.

Human pancreas-specific protein. A diagnostic and prognostic marker in acute pancreatitis and pancreas transplantation

CONCLUSION

Human pancreas-specific protein (hPASP) is a very sensitive reflector of the extent of pancreatic necrosis on the cellular level, and is of both diagnostic and prognostic value in acute pancreatitis. Furthermore, it allows the estimation of the severity of graft pancreatitis soon after simultaneous renal and pancreatic transplantation.

BACKGROUND

Diagnosis of acute pancreatitis (AP) has been improved in the past 15 yr as new methods for the determination of specific pancreatic enzymes have been developed. However, these enzymes have no prognostic implications. In this prospective study, we evaluated the role of human pancreas-specific protein (hPASP) in comparison with pancreatic amylase and C-reactive protein (CRP) in acute pancreatitis and pancreas transplantation.

PATIENTS AND METHODS

The study included 40 patients (22 female, 18 male; mean age 51 yr, range 22-88 yr) with AP and 7 patients (2 female, 5 male; mean age 37 yr, range 25-49 yr) with type I diabetes and renal insufficiency who underwent simultaneous kidney and pancreas transplantation. By means of contrast-enhanced computed tomography (CT) and/or intraoperative findings, patients were judged to have edematous-interstitial (AIP, n = 20, mean age 55.2 yr, range 24-88 yr) or necrotizing pancreatitis (NP, n = 20, mean age 46.3 yr, range 22-81 yr). Serum hPASP concentration was measured daily by a commercial radioimmunoassay technique. In 25 healthy subjects and in several control groups (35 patients with chronic pancreatitis, 20 patients with pancreatic carcinoma and 80 patients with different gastrointestinal diseases) a single blood specimen was taken at hospital admission for the determination of the normal range of hPASP and for specificity analysis.

RESULTS

The upper normal value for hPASP in healthy subjects was found to be 52 ng/mL. Serum hPASP was elevated in all patients suffering from AP, with a median of 343 ng/mL (lower-upper quartile: 192-478 ng/mL) at hospital admission. In the daily serum monitoring with respect to the onset of symptoms, significantly higher hPASP levels were found in NP compared with AIP after day 2 (p < 0.001). In patients with NP, peak values of hPASP correlated significantly with the extent of pancreatic necroses measured by contrast-enhanced CT-scanning, whereas CRP did not. Six patients of the transplantation group had the same serum hPASP course as AIP, with almost normal values on the third postoperative day. One patient had elevated levels throughout the observation period. This patient suffered from necrotizing graft pancreatitis, confirmed by relaparotomy, and died because of subsequent septic complications.

Serum procarboxypeptidase B, amylase and lipase in chronic renal failure

Procarboxypeptidase B (human pancreas-specific protein) has been reported to be a good serum marker for the diagnosis of acute pancreatitis. The current study was conducted in order to evaluate the frequency and degree of elevated serum levels of procarboxypeptidase B in chronic renal failure and their correlations with serum levels of amylase, lipase and renal function tests. Blood samples were taken from 84 asymptomatic patients with chronic renal failure, including 34 patients with periodical haemodialysis and 50 patients without haemodialysis. Serum levels of procarboxypeptidase B, amylase, lipase, creatinine and blood urea nitrogen were measured. Serum levels of procarboxypeptidase B in 84 patients were 63.4 +/- 5.5 micrograms/L significantly greater than the figure of 29.6 +/- 1.6 micrograms/L in healthy adults in our previous report (P < 0.0001). There was a significant difference in serum levels of PCPB between patients with and without haemodialysis (78.0 +/- 9.4 vs 53.6 +/- 6.3 micrograms/L; P < 0.01). The frequencies of elevated serum levels of procarboxypeptidase B, amylase and lipase greater than upper normal limits were 27.4, 35.7 and 26.2%, respectively. The frequencies of elevated PCPB in patients with and without haemodialysis were 38.2 and 20%, respectively. Only one patient had a serum procarboxypeptidase B level greater than three-fold the upper normal limit. A significant correlation was found between procarboxypeptidase B and lipase (r = 0.785; P < 0.0001). No significant correlation was noted between procarboxypeptidase B vs amylase or renal function tests. In conclusion, in patients with chronic renal failure, the elevation of serum procarboxypeptidase B is as common as the elevations of other pancreatic enzymes.