Aprotinin and Na2CaEDTA in experimental hemorrhagic pancreatitis in pigs

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.

Pancreatic enzyme-induced pancreatitis and systemic complications in rats

Effects of retrograde injection into the pancreatic duct and intravenous infusion of pancreatic enzymes and bile salt on the pancreas and other vital organs such as the liver and the lung were investigated in rats. Intraductal injection (1 ml/kg) of alpha-chymotrypsin (50-100 mg/ml), trypsin (10-100 mg/ml), pancreatic elastase (10 mg/ml), lipase (100-300 mg/ml), pancreatic kallikrein (25 mg/ml) and sodium taurocholate (50 mg/ml) solutions significantly increased pancreatic water content. Alpha-chymotrypsin, pancreatic elastase, taurocholate and trypsin elicited gross pancreatic hemorrhage. In contrast, lipase and kallikrein elicited gross pancreatic edema, but not hemorrhage. Intravenous infusion of trypsin (1 mg/kg/hr) and pancreatic elastase (10 mg/kg/hr) significantly increased pulmonary vascular permeability in rats, whereas infusion of neutrophil elastase (0.3 mg/kg/hr) did not elicit these effects. Only trypsin slightly reduced arterial oxygen pressure. These results show pancreatic enzymes and bile salts induce pancreatic inflammation after retrograde injection into the pancreatic duct in rats. Furthermore, trypsin and pancreatic elastase extravasation into the vascular system can lead to pulmonary dysfunction in rats.

Inhibition of serum phospholipase-A2 in acute pancreatitis by pharmacological agents in vitro

Phospholipase-A2 has been suggested as having a role in the pathophysiology of acute pancreatitis. The inhibition of phospholipase-A2 was studied in vitro using 17 pharmacological agents in the search for a specific therapy for acute pancreatitis. The inhibitory effect was tested using an isotopic assay system with 2-palmitoyl-(1-14C)-labelled dipalmitoyl phosphatidylcholine as a substrate and 10 microliters of serum from patients with acute necrotizing pancreatitis as an enzyme source. Among all agents tested, anti-inflammatory drugs inhibited enzyme activity most significantly: indomethacin (9.0 x 10(-3) mol l-1) decreased the phospholipase-A2 activity to one- tenth. The weak inhibitory effect could also be demonstrated using a lower concentration of 2 x 10(-5) mol l-1, which can be achieved after intravenous administration of 50 mg of this drug. The other drugs inhibited the enzyme activity at concentrations higher than those achieved after intravenous injections in clinical use. Diclofenac (3.1 x 10(-2) mol l-1) reduced the phospholipase-A2 activity by 93%, ketoprofen (2.0 x 10(-2) mol l-1) or chlorpromazine (1.4 x 10(-2) mol l-1) by 90%, tobramycin (1.7 x 10(-2) mol l-1) by 84%, doxycycline (9.0 x 10(-3) mol l-1) by 61%, dexamethasone (1.7 x 10(-3) mol l-1) by 62%, methylprednisolone (3.8 x 10(-2) mol l-1) by 50%, and pindolol (1.0 x 10(-4) mol l-1) by 59%. A weak inhibition of phospholipase-A2 activity was demonstrated by betamethasone, bupivacaine, digoxin, hydrocortisone, lidocaine, metoprolol, propranolol, and vancomycin. Indomethacin proved the most potent of the tested agents in inhibiting phospholipase-A2 activity in serum from patients with acute pancreatitis and should be further studied in vivo.

Phospholipases in biology and medicine

Phospholipases, a group of enzymes that catalyze the hydrolysis of membrane phospholipids, are classified according to the bond cleaved in a phospholipid into PLA1 (EC 3.1.1.3), PLA2 (EC 3.1.1.4), PLB (EC 3.1.1.5), PLC (EC 3.1.4.3), and PLD (EC 3.1.4.4). This paper reviews source and structure of PLA2 and the involvement of PLA2 and PLC in several biological phenomena, such as, signal transduction, photoreception, biosynthesis of lung surfactant, sperm motility, and fertilization. New assays for PLA2 activity and concentration in biological fluids are discussed. Phospholipases are involved in many inflammatory reactions by making arachidonate available for eicosanoid biosynthesis. The determination of PLA2 activity and mass concentration in plasma is useful in the diagnosis and prognosis of pancreatitis and of septic shock. Naturally occurring phospholipase inhibitors, such as lipocortins act as second messengers in the anti-inflammatory response to steroids. Lipocortins may be valuable therapeutic agents, because they are more specific in their anti-inflammatory action than glucocorticoids; therefore, they are less likely to produce harmful side effects.

Effect of FOY-305 (camostate) on severe acute pancreatitis in two experimental animal models

Two models of severe acute pancreatitis were chosen and pancreatitis induced by sodium taurocholate and by a choline-deficient ethionine-supplemented diet, to evaluate the effectiveness of FOY-305 (camostate), a new synthetic trypsin inhibitor. Prophylactic administration of FOY-305 had a significantly favorable effect on the course of the sodium taurocholate-induced disease and on the survival rate of the treated group. A beneficial effect on the amylase and lipase content in serum and ascites was found, but no effect was observed on enzyme concentration in pancreatic tissue or on the degree of histologically detectable organ destruction. Therapeutic administration of FOY-305 had a significantly positive influence when infused directly, 5 and 30 min after the operation, whereas enzyme increase and organ destruction remained unaffected. FOY-305 showed a beneficial effect when given prophylactically or therapeutically at the beginning of the pancreatitis induced by a CDE diet, with no significant change in enzyme increase and degree of organ destruction. The favorable effect on survival time and rate in the early phase of these two severe experimental forms of pancreatitis may justify an evaluation of FOY-305 in a clinically controlled study.