Involvement of heparin cofactor II in chymotrypsin neutralization and in the pancreatic proteinase-antiproteinase interaction during acute pancreatitis in man

Can postendoscopic retrograde cholangiopancreatography pancreatitis be prevented by a pharmacological approach?

Acute pancreatitis remains the most frequent complication of endoscopic retrograde cholangiopancreatography (ERCP), with reported incidence rates that have changed little over several decades. Patient- and procedure-related risk factors for post-ERCP pancreatitis (PEP) are well-defined. Effective measures to prevent PEP have been identified, including improvements in cannulation techniques and pancreatic stenting, as well as pharmacological intervention. Pharmacotherapy has been widely studied in the prevention of PEP, but the effect in averting PEP has been inconclusive. Although pharmacological prophylaxis is appealing, attempts to find an ideal drug are incomplete. Most available data on the efficacy of pharmacological agents for PEP prophylaxis have been obtained from patients at average risk for PEP. However, recently, a randomized prospective controlled trial of rectal nonsteroidal anti-inflammatory drugs (NSAIDs) to prevent PEP in high-risk patients was published. The results revealed that rectal indomethacin reduced the incidence of PEP significantly. Thus, rectal administration of diclofenac or indomethacin immediately before or after ERCP is used routinely to prevent PEP. However, additional studies with NSAIDs using large numbers of subjects are necessary to confirm the prophylactic effect of these drugs and to establish whether they act synergistically with other prophylactic interventions, including pancreatic stenting.

Prevention of Post-ERCP Pancreatitis

Pancreatitis is the most common complication of ERCP. It can be associated with substantial morbidity. Hence, the minimization of both the incidence and severity of post-ERCP pancreatitis is paramount. Considerable efforts have been made to identify factors that may be associated with an increased risk of this complication. In addition, both procedure- and pharmacological-related interventions have been proposed that may prevent this complication. This paper outlines these interventions and presents the evidence to support their use in the prevention of post-ERCP pancreatitis.

Low-dose heparin for the prevention of post-ERCP pancreatitis: a randomized placebo-controlled trial

BACKGROUND

As suggested by observational and animal studies, heparin has antiinflammatory effects that could prevent acute post-endoscopic retrograde cholangiopancreatography (ERCP) pancreatitis. Low-molecular-weight heparin did not reduce the incidence of post-ERCP pancreatitis in a controlled study. The current study aimed to determine whether prophylactic administration of low-dose unfractionated heparin, which has potentially more antiinflammatory capability, can prevent acute post-ERCP pancreatitis.

METHODS

Patients scheduled for ERCP in the authors' department were randomized to receive unfractionated heparin (5,000 IU) or placebo (saline solution 0.5 ml) administered subcutaneously 20 to 30 min before the ERCP. Patients who had undergone endoscopic sphincterotomy in the past were excluded from the study. Post-ERCP pancreatitis was defined according to criteria established by Cotton: abdominal pain combined with a threefold elevation of blood amylase 24 h after the ERCP.

RESULTS

The study enrolled 106 patients. One patient was excluded from the analysis due to inaccessible papilla of Vater, leaving 51 patients in the heparin group and 54 in the placebo group, for a total of 105 patients (62 women and 43 men) with a mean age of 64.6 years. The rate of post-ERCP pancreatitis was not different between the groups (heparin, 4 patients, 7.8%; placebo, 4 patients, 7.4%). Two patients in each group experienced mild bleeding.

CONCLUSIONS

The study did not demonstrate a significant effect of low-dose unfractionated heparin in the prevention of post-ERCP pancreatitis. A multicenter trial with a larger number of patients is needed to demonstrate a benefit from this drug.

Post-ERCP pancreatitis and its prevention

Pancreatitis remains the most common severe complication of endoscopic retrograde cholangiopancreatography (ERCP), and typically develops in 5-7% of patients. Although most post-ERCP pancreatitis (PEP) is mild, severe pancreatitis and its complications (including a systemic inflammatory response or the development of pseudocysts or pancreatic necrosis) can occur, and in rare cases death can result. A means of preventing PEP in all patients who undergo the procedure remains elusive. Proper patient selection for ERCP is critical to avoid unnecessary risk. Pharmacologic attempts to prevent PEP have been largely unsuccessful; encouraging results have been difficult to validate. Prophylactic stenting of the pancreatic duct and minimally traumatic cannulation techniques offer the most promise as a means of preventing PEP. This manuscript reviews risk factors for PEP as well as pharmacologic and procedural means that can be used to reduce its incidence.

Disorders of hemostasis during the surgical management of severe necrotizing pancreatitis

OBJECTIVES

Several clinical studies of severe necrotizing pancreatitis (SNP) suggest profound activation of coagulation as well as activation of the fibrinolytic system. The aim of this study was to evaluate the hemostatic derangements in patients who were managed for SNP.

METHODS

Forty-one operated-on patients with SNP were analyzed regarding clinical outcome and activation of the coagulation systems. Serial measurement of coagulation, anticoagulation, and fibrinolysis parameters: prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen, antithrombin III (AT III), protein C, plasminogen activator inhibitor-1 (PAI-1), d-dimer, alpha2-antiplasmin, and plasminogen were performed on days 1, 3, 5, 7, 10, and 14 after the initial operation. According to treatment outcome at the end of study, groups of 26 survivors and 15 nonsurvivors were compared.

RESULTS

Nonsurvivors had significantly lower levels of activity of protein C and AT III, and higher concentrations of d-dimer and PAI-1 than survivors. The other measured parameters did not show significant differences between the compared groups of patients.

CONCLUSIONS

Changes in protein C, AT III, d-dimer and PAI-1 levels indicate exhaustion of fibrinolysis and coagulation inhibitors in patients with poor outcome during the course of SNP.

Heparin cofactor II deficiency

OBJECTIVES

To review of the state of the art relating to congenital heparin cofactor II deficiency as a potential risk factor for thrombosis, as reflected by the medical literature and the consensus opinion of recognized experts in the field, and to make recommendations for the use of laboratory assays for assessing this thrombotic risk in individual patients.

DATA SOURCES

Review of the medical literature, primarily from the last 10 years.

DATA EXTRACTION AND SYNTHESIS

After an initial assessment of the literature, including review of clinical study design and laboratory methods, a draft manuscript was prepared and circulated to participants in the College of American Pathologists Conference XXXVI: Diagnostic Issues in Thrombophilia. Recommendations were accepted if a consensus of experts attending the conference was reached. The results of the discussion were used to revise the manuscript into its final form.

CONCLUSIONS

Consensus was reached that there is insufficient evidence to recommend testing for heparin cofactor II deficiency in patients with thromboembolic disease.

Complications of endoscopic sphincterotomy: can heparin prevent acute pancreatitis after ERCP?

BACKGROUND

An exploratory analysis of a prospective study of risk factors for acute pancreatitis after ERCP combined with endoscopic sphincterotomy showed that the frequency of acute pancreatitis was lower in patients who received heparin compared with patients not treated with heparin. The study was continued to further analyze the effect of heparin on the frequency of acute pancreatitis.

METHODS

Potential risk factors for acute pancreatitis and outcomes were evaluated prospectively for all ERCP procedures with endoscopic sphincterotomy performed between September 1994 and December 1998. The results were analyzed by univariate and multivariate methods to determine risk factors for complications. Heparin was administered to 32.9% of the patients (heparin group [HEP group], n = 268) for various clinical reasons (low-molecular-weight heparin, n = 208, unfractionated heparin n = 60). A group of 547 patients who did not receive heparin served as control patients (CON group).

RESULTS

Eight hundred fifteen patients underwent ERCP with endoscopic sphincterotomy; acute pancreatitis occurred in 6.4% (n = 52). The frequency of acute pancreatitis was significantly lower in the HEP group versus the CON group in the final multivariate model, which included significant risk factors for acute pancreatitis (HEP group: 3.4%, 9/268 vs. CON group: 7.9%, 43/547; p = 0.005). HEP did not increase the risk of hemorrhage (HEP group: 1.1%, 3/268, 2 severe, none fatal vs. CON group: 2.0%, 11/547, 3 severe, 2 fatal). HEP (p = 0.005; OR 0.3: 95% CI [0.16, 0.73]) and the number of risk factors present (p = 0.0001; OR 2.5: 95% CI [1.80, 3.50]) influenced the frequency of acute pancreatitis independently.

CONCLUSIONS

Heparin was significantly associated with an extremely low frequency of post-ERCP pancreatitis without increasing the risk of hemorrhage after endoscopic sphincterotomy. Because this effect could not be attributed to other known or suspected confounders, our conclusion was that heparin administration before ERCP reduces the risk of pancreatitis.

Biotinylated aprotinin: a versatile probe for the detection of serine proteinases on western blots

The present study was undertaken to provide a highly sensitive detection system for the identification and characterisation of serine proteinases separated by sodium dodecyl sulphate polyacrylamide gel electrophoresis. Biotinylated aprotinin of high specific activity (88-92% active) was prepared (i) by reaction of aprotinin directly with N-hydroxy sulfosuccinimidyl-6-(biotinamido) hexanoate, and (ii) by reaction of aprotinin-trypsin complex with N-hydroxy succinimidobiotin. Both biotinylated aprotinin samples were suitable as probes for the detection of the serine proteinases, neutrophil elastase and cathepsin G, pancreatic trypsin and chymotrypsin and plasmin on nitrocellulose blots. Specific irreversible chloromethyl ketone proteinase inhibitors used in combination with this detection system enabled respective proteinases to be selectively inactivated and thus positively identified. The biotinylated aprotinin detection system was highly sensitive and could detect as little as 0.2 ng (8.5 fmol) of active proteinase (trypsin). In summary, a method has been developed for the sensitive detection of serine proteinases separated by SDS-PAGE. The method is more sensitive and convenient to perform than conventional zymography and significantly, when used in conjunction with specific serine proteinase inhibitors or specific antibodies can yield appreciable information on the identity of the respective serine proteinases being examined. Furthermore the molecular mass of the serine proteinase may be reliably obtained by this method. This method should find application in identifying the role that serine proteinases play in the etiopathogenesis of connective tissue disorders.

An enzyme-linked immunosorbent assay for heparin cofactor II (HCII). Application to the measurement of HCII in clinical materials

Heparin cofactor II (HCII) is a thrombin inhibitor in human plasma, the activity of which is enhanced by heparin and dermatan sulfate. To measure the plasma antigen concentration of HCII, an enzyme-linked immunosorbent assay (ELISA) has been developed, and this is based on the use of polyclonal anti-HCII IgG, both as the antigen-capturing antibody and as the labelled antibody. The intra- and inter-assay reproducibilities have been calculated to be less than 6%. HCII antigen concentrations evaluated with this ELISA technique in clinical plasma samples correlated well with those determined by electroimmunodiffusion and with HCII activities evaluated using a functional assay (r = 0.909 and r = 0.930, P less than 0.0001). Since the correlation between HCII deficiency and thrombosis is still a controversial issue, the ELISA technique described in this report could be a useful tool for the large-scale studies needed to determine the prevalence of HCII deficiency in healthy individuals and in patients with a history of thrombosis.