Platelet activation by human pancreatic fluid.

The effects of human pancreatic fluid (HPF) on platelet aggregation and activation were studied. HPF, obtained at operation from nine patients with chronic pancreatitis and two with pancreas cancer, was pooled, lyophilized, and adjusted to a concentration of 1 mg protein/cc of 0.9% saline after dialysis. Platelet aggregation was evaluated by measuring platelet count after iv administration of HPF to five rabbits in concentrations ranging from 0.2 to 2.0 mg/kg. Platelet activation was evaluated by adding 0.1-ml aliquots of pooled HPF in various concentrations to 0.9 ml of human platelet-rich plasma. After a 15-min incubation at 37 degrees C, the platelets were removed by centrifugation and the supernatant examined for platelet-release products. Serotonin was measured by high-performance liquid chromatography (HPLC) and platelet factor 4 and thromboxane B2 were measured by radioimmunoassay. A significant decrease in rabbit platelet count signifying platelet aggregation was seen after iv administration of 1.0 mg/kg (P less than 0.05) and 2.0 mg/kg (P less than 0.001) HPF. Platelet activation was confirmed by a significant increase (P less than 0.05) in serotonin, platelet factor 4, and thromboxane B2 at almost all concentrations of HPF. This study indicates that HPF induces platelet aggregation and activation and suggests that platelet contact with pancreatic exocrine fluid may have both local and systemic effects that are important in the pathophysiology of acute pancreatitis.

Comparative study of protease inhibitors on coagulation abnormalities in canine pancreatitis.

Coagulation abnormalities induced by pancreatitis were studied in 36 dogs. The 12 dogs in group I underwent a duodenotomy alone. The six dogs in groups II, III, IV, and V had pancreatitis induced by bile injection (1 cc/kg) into the pancreatic duct. Twenty minutes after bile-induced pancreatitis, group III was given 1.0 mg/kg aprotinin (trasylol), group IV was given 10 mg/kg S-2441, a new synthetic protease inhibitor, and group V was given 0.5 mg/kg alpha 2-antitrypsin by intravenous infusion over 10 min. Blood was drawn for amylase, protime (PT), partial thromboplastin time (PTT), fibrinogen, and platelets, in addition to markers of hypercoagulation, fibrinopeptide A, and antithrombin III, and markers of fibrinolysis, B beta 15-42 immunoreactive peptide (IP), and alpha 2-antiplasmin at baseline, 1/2, 1, 3, 6, 24, 48, and 72 hr after duodenotomy or bile injection. There was no significant difference in PT, platelets, antithrombin III, and fibrinopeptide A among the five groups. With the induction of pancreatitis (group II), serum amylase was significantly elevated but fibrinogen only became elevated at 24 hr and PTT at 48 hr. The increase in B beta 15-42 IP seen 30 min after induction of pancreatitis and the decrease in alpha 2-antiplasmin were blunted by aprotinin, alpha 1-antitrypsin, and S-2441, but inhibition of the rise in amylase and B beta 15-42 IP only reached significance with S-2441 (P less than 0.05). Pancreatitis-induced fibrinolysis was inhibited by S-2441 suggesting that synthetic protease inhibitors may play a therapeutic role in pancreatitis.

Effects of protease inhibitors on coagulation abnormalities in acute canine pancreatitis.

Coagulation abnormalities associated with severe pancreatitis were studied in 24 dogs. Group I consists of six control subjects who had duodenotomy alone. Group II consists of six dogs with pancreatitis induced by bile injection ( lcm3 /kg) into the pancreatic duct. The six dogs in Group III and the six in Group IV were given aprotinin (trasylol) 1.0 mg/kg and S-2441 (10mg/kg), a new synthetic protease inhibitor, respectively. These were given over 10 minutes by intravenous infusion, 20 minutes after bile induced pancreatitis. Blood was drawn for amylase, prothrombin time (PT), partial thromboplastin time (PTT), fibrinogen, and platelets, in addition to markers for hypercoagulation, fibrinopeptide A, antithrombin III, and markers for fibrinolysis, B beta 15-42 immunoreactive peptides and alpha 2 antiplasmin at baseline, 30 minutes, 1 hour, 3 hours, 6 hours, and daily for 3 days after injection of bile or duodenotomy. There was no significant difference in PT, platelets, antithrombin III, and fibrinopeptide A among the four groups. Fibrinogen levels and PTT were minimally elevated in animals with bile induced pancreatitis, but these changes reached significance only at 24 hours and 48 hours, respectively (P less than 0.05). Immunoreactive B beta 15-42 became elevated at 30 minutes indicating fibrinolysis in animals with pancreatitis, and these changes were significant compared with Group I control subjects (P less than 0.05) throughout the study. Levels of alpha 2 antiplasmin were decreased in Group II animals with pancreatitis, which also suggests fibrinolysis. Amylase was elevated in Group II animals with pancreatitis (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Molecular markers of hemostatic disorders: implications in the diagnosis and therapeutic management of thrombotic and bleeding disorders.

With current technological advances, it is now possible to measure in less than 50 microL of plasma picomolar amounts of circulating products of platelet activation, products of protease activation related to coagulation and fibrinolytic pathways, and prostaglandin metabolites formed during a physiologic or pathologic process. Most of these markers, which circulate in blood in nanogram or picogram amounts per milliliter during or after pathologic activation, provide pertinent information on the status of a patient in terms of specificity and early detection, and will be of crucial value in the diagnosis of hemostatic defects and the management of newer antithrombotic drugs that cannot be monitored by currently available assays. Currently, 125I- and 3H-based simple radioimmunoassays are available for platelet factor 4, beta-thromboglobulin, fibrinopeptide A, B beta 15-42 related peptides, thromboxane B2, and the prostaglandins 6-keto-PGF1 alpha and PGE2. Nonisotopic methods such as enzyme-linked immunosorbent assays and fluoroimmunoassays are being developed. Serotonin and ADP, products of platelet activation, are measurable by liquid-chromatographic, immunoenzymatic, and spectrophotofluorometric methods. Analytical methods for fibrin split products (fragments D and E) and serine protease inhibitor complexes such as thrombin-antithrombin-III, factor Xa-antithrombin-III, and kallikrein-C1-esterase are also being developed. We have evaluated all of these methods and found them to be very sensitive to those components of endogenous activation of the hemostatic system listed above.