Postoperative venous thromboembolism and brain tumors: Part II. Hemostatic profile.

Preoperative hemostatic data were obtained on 42 brain tumor patients and correlated with the subsequent occurrence of venous thrombosis detected with 125I-labeled fibrinogen leg scans. The occurrence of thrombosis correlated significantly with an increased prothrombin time, plasminogen, and total fibrinolytic activity and a decreased fibrinogen level. This overall trend in the group of patients with postoperative thrombosis indicates that the hemostatic disorder noted in brain tumor patients is most closely related to a subclinical form of chronic disseminated intravascular coagulation syndrome. Differences in hemostatic parameters seen with the various types of brain tumors suggest that biological factors specific to each tumor are likely responsible for the described hemostatic disorder and support the need for further research directed at the tumor tissue level.

Thrombin inhibition enhances tissue-type plasminogen activator-induced thrombolysis and delays reocclusion.

The objectives of this study were to test the hypotheses that thrombin inhibitors 1) enhance tissue-type plasminogen activator (t-PA)-induced coronary thrombolysis and 2) prevent or delay coronary artery reocclusion. Seventy-one dogs developed occlusive coronary thrombi after introducing a copper coil into the left anterior descending coronary artery (LAD). Coronary blood flows were monitored by an externally positioned pulsed Doppler flow probe. t-PA was given with or without heparin at different times after LAD occlusions. In some experiments, hirugen, a synthetic hirudin-based peptide and specific thrombin inhibitor, was given as 4 mg/kg i.v. bolus and 3 mg.kg-1.h-1 i.v. infusion at 30 min after LAD occlusion with t-PA and a bolus of heparin. Thrombolysis times were significantly shorter in t-PA- and heparin-treated dogs than in dogs treated with t-PA alone. Reocclusion times were significantly longer in t-PA- and heparin-treated dogs than in dogs treated with t-PA alone. Continuous heparin infusions prolonged reocclusion times to greater than 180 min in all treated dogs. The addition of hirugen to t-PA plus one bolus heparin prolonged reocclusion times to 90 +/- 6 min in dogs with 30-min thrombi. Thus heparin enhances t-PA-induced thrombolysis and delays reocclusion. Addition of a specific thrombin inhibitor, such as hirugen, to heparin enhances its effect on delaying reocclusion.

Plasma fibrinolytic profile in patients with brain tumors.

Changes in the fibrinolytic and coagulation values measured preoperatively in brain tumor patients have not been done systematically using individual rather than global assays. Such measurements can provide meaningful information on the status of tumor-host interactions and could potentially help in predicting thromboembolic and hemorrhagic tendencies. A complete fibrinolytic profile including total fibrinolytic activity (TFA), tissue plasminogen activator (t-PA), plasmin inhibitor (PI), plasminogen activator inhibitor (PAI), protein C (PC) and plasminogen (PLG) was obtained preoperatively in 114 brain tumor patients. PLG and PI did not show much variation among the groups. TFA was slightly reduced (15%) in patients with malignant brain tumors. t-PA, however, was abnormally low in several patients and in almost 40% of patients with brain metastasis. PAI was above the upper limit of normal in approximately 50% of the patients but particularly in glioma, glioblastoma and metastasis patients. Finally, mean PC was abnormally increased in the glioblastoma and metastasis groups (p less than 0.001). This is the first study that has measured protein C in brain tumor patients. In conclusion, plasma fibrinolytic levels show marked changes in a substantial number of brain tumor patients prior to surgery--suggesting an ongoing tumor-host interaction.

Ancrod causes rapid thrombolysis in patients with acute stroke.

Clot lysis is desirable in patients with thrombi in arteries and arterioles by a safe rapidly-acting thrombolytic agent. Ancrod cleaves fibrinogen; the resulting circulating ancrod-fibrin stimulates fibrinolysis. Ancrod action and effect were studied in 20 patients with acute developing stroke in a double-blind, placebo-controlled study. Patients were randomly assigned to one of two treatment groups, and received either normal saline or ancrod 0.5 mu/kg in normal saline administered as a constant-rate intravenous infusion over 6 hours. Subsequent doses of ancrod (or saline placebo) were determined daily thereafter for a total treatment period of 7 days. Neither bleeding nor re-thrombosis occurred within the 90 day follow-up period. That ancrod acted rapidly was shown by a significant decrease in functional plasminogen activator inhibitor (PA-I) within 60 minutes, and by significant elevations of fibrin(ogen) degradation products (FDP) and D-dimer within 3 and 4 hours. The biological effect of fibrinolysis in ancrod infused patients was demonstrated by a greater improvement in stroke score when compared to those infused with saline.

Simultaneous administration of thromboxane A2- and serotonin S2-receptor antagonists markedly enhances thrombolysis and prevents or delays reocclusion after tissue-type plasminogen activator in a canine model of coronary thrombosis.

Dynamic changes of the thrombus after its formation due to platelet activation may affect the speed of thrombolysis. In the present study, we wanted to evaluate the role played by thromboxane A2 (TXA2) and serotonin (5HT) in mediating platelet activation during lysis of intracoronary thrombi with human recombinant tissue-type plasminogen activator (t-PA). Coronary thrombi were induced in 26 anesthetized, open-chest dogs by inserting a copper coil into the left anterior descending coronary artery (LAD). LAD blood flow was monitored throughout the experiment by means of a Doppler flow probe placed proximally to the coil. Presence of the thrombus was documented for 30 minutes. The dogs were then assigned to one of four groups as follows: group 1 dogs (n = 8), serving as controls, received a bolus of heparin (200 units/kg) and a bolus of t-PA (80 micrograms/kg) followed by a continuous infusion (8 micrograms/kg/min) for up to 90 minutes or until reperfusion was achieved; group 2 dogs (n = 10) received, immediately before heparin and t-PA, an intravenous bolus of SQ29548 (SQ) (0.4 mg/kg, a selective TXA2-receptor antagonist) and LY53857 (LY) (0.2 mg/kg, a selective serotonin S2-receptor antagonist); group 3 dogs (n = 7) received, before heparin and t-PA, an intravenous bolus of SQ alone (0.4 mg/kg); and group 4 dogs (n = 7) received, before heparin and t-PA, an intravenous bolus of LY alone (0.2 mg/kg). After thrombolysis, all dogs were monitored for 90 minutes or until a persistent reocclusion occurred.(ABSTRACT TRUNCATED AT 250 WORDS)

Fibrinolysis in glomerulonephritis treated with ancrod: renal functional, immunologic and histopathologic effects.

The effects of a 14-day course of ancrod on fibrinolysis, renal function and structure, and immunologic findings are reported in 37 patients with glomerulonephritis. Patients were divided into two groups. In the first, the level of fibrin degradation products within 48 h was relatively low (less than 1 mg/ml). In these patients there was a linear relationship between changes in levels of fibrin degradation products and fibrinogen, suggesting that fibrin degradation products derived from ancrod-cleaved-fibrinogen in the circulating pool; in most, level of plasma alpha 2-antiplasmin before treatment was elevated. In the second, the level of fibrin degradation products within 48 h was high (greater than 1 mg/ml). Compared with the change in fibrinogen, a disproportionate increase in levels of fibrin degradation products suggested that a significant amount derived from sources other than plasmin digested ancrod-cleaved-fibrinogen, thus reflecting effective fibrinolysis, perhaps also in tissues; in most, the level of plasma alpha 2-antiplasmin was normal before treatment. In those with initial high levels of fibrin degradation products, higher levels persisted throughout treatment, changes in other fibrinolysis components were greater, and plasminogen activator inhibitor levels became normal. In patients with initial high but not with initial low response in fibrin degradation products renal function improved within 24 to 48 h and continued to improve thereafter; there was an immediate but temporary increase in proteinuria. Microvascular thrombosis decreased significantly, indicating effective removal of fibrin from glomeruli. The relation of early fibrinolysis to changes in immunologic and histopathologic findings was analyzed in patients with lupus nephritis. With ancrod, there was an increase toward normal of serum C3 and C4, a decrease in serum Igs, gamma globulin and anti-dsDNA antibody and in glomerular C3 and Ig deposits, suggesting that ancrod had favorable effects on immunologic factors. There were no clinical differences in patients with initial high and low responses, but the relationship of microvascular and inflammatory indexes before treatment differed. Initial renal biopsies and those after treatment were carried out on average 28 days apart. Inflammatory and microvascular indexes and glomerular thrombi decreased in patients with initial high levels of fibrin degradation products; fibrosclerosis index and glomerular sclerosis increased in patients with initial low levels of fibrin degradation products. Fibrinolysis expressed as the 48 h (fibrin degradation products/fibrinogen) ratio, correlated inversely with change in fibrosclerosis index and glomerular sclerosis in the whole group, and especially in those with initial high levels of fibrin degradation products.(ABSTRACT TRUNCATED AT 400 WORDS)

Use of ancrod in acute or progressing ischemic cerebral infarction.

Ancrod has been used in Europe for over 15 years for peripheral vascular disease, deep vein thrombosis, and central retinal venous thrombosis, and in patients at risk for thromboembolism. In a double-blind, randomized, placebo-controlled study at University Hospitals in Cincinnati, 20 acute cerebral infarction patients received a series of IV infusions of ancrod (ten) or placebo (ten) for seven days. Early fibrinolysis with a small decrease in fibrinogen was observed, and d-dimers were elevated at four hours, indicating early clot lysis. At three months, patients with moderate to severe strokes (less than 40 on the Scandinavian Stroke Scale) in the ancrod group showed average improvement by a factor of 3 over the placebo group. No bleeding, abnormal laboratory results, or deaths occurred, but ancrod was discontinued in one patient who had seizures. As a result of this study, a double-blind multicenter international clinical trial to further assess the safety and effectiveness of ancrod is being planned.

Fish oil has beneficial effects on lipids and renal disease of nephrotic rats.

The effects of fish oil on serum lipids, eicosanoid production, fibrinolysis, and renal disease of nephrotic rats were studied. Three groups of rats were given adriamycin to induce nephrotic syndrome. They were pair-fed diets containing 14% beef fat, 3%, and 14% fish oil, and killed at 4 weeks. Marked beneficial effects of the fish oil on plasma triglycerides, total cholesterol, and LDL cholesterol were observed. Fish oil suppressed dienoic eicosanoid production. Protection of renal function and morphology was achieved in the fish oil fed groups, as evidenced by lower serum creatinine levels and lesser degrees of tubular dilatation and intraluminal protein in the kidney tubules. We conclude that fish oil, rich in n-3 fatty acids, is beneficial to the plasma lipids and may prevent progression of renal disease in this model of nephrotic syndrome. These two events may be interrelated.

Mediation of reocclusion by thromboxane A2 and serotonin after thrombolysis with tissue-type plasminogen activator in a canine preparation of coronary thrombosis.

Human recombinant tissue-type plasminogen activator (rt-PA) has been shown to be an effective and safe agent for coronary thrombolysis in patients with acute myocardial infarction. However, thrombolysis is associated with a high rate of acute reocclusion after discontinuation of rt-PA. The goals of the present study were to assess whether reocclusion after thrombolysis is caused by intracoronary platelet aggregation and to determine the role of thromboxane A2 (TxA2) and serotonin (5HT) in mediating this phenomenon. Accordingly, coronary thrombosis was induced in anesthetized, open-chest dogs by insertion of a copper coil into the left anterior descending coronary artery (LAD). LAD blood flow was monitored throughout the experiment by means of a Doppler flow probe placed proximally to the coil. Thrombolysis was achieved with rt-PA (0.05 mg/kg bolus + micrograms/kg/min infusion) in 23 +/- 3 min. rt-PA was then discontinued and each animal received a bolus of heparin (150 U/kg) every hour. Reperfusion was followed by repeated cycles of gradual occlusions followed by spontaneous restorations of blood flow (cyclic flow variations, CFVs) before a persistent occlusion recurred. In control dogs (n = 6), heparin alone did not prevent CFVs and reocclusion time was 25 +/- 4 min. Administration of an intravenous bolus of 0.2 +/- 0.06 mg/kg SQ29548, a TxA2/prostaglandin H2-receptor antagonist, and an intravenous bolus of 0.2 +/- 0.04 mg/kg ketanserin, a 5HT2-receptor antagonist, completely abolished CFVs in six of six dogs and reocclusion time was greater than 158 +/- 14 min (p less than .01).(ABSTRACT TRUNCATED AT 250 WORDS)

Ancrod decreases the frequency of cyclic flow variations and causes thrombolysis following acute coronary thrombosis.

The potential use of ancrod, a purified isolate from the venom of the Malaysian pit viper, Agkistrodon rhodostoma, in decreasing the frequency of cyclic flow variations in severely stenosed canine coronary arteries and causing thrombolysis of an acute coronary thrombus induced by a copper coil was evaluated. Open-chest, anesthetized dogs were used. Ancrod was given intravenously (8 U/kg) over 1 hour and caused a significant reduction in the frequency of cyclic flow variations (5.8 +/- 0.7 to 3.6 +/- 0.8 cyclic flow variations per 30 minutes, p less than 0.05), whereas control animals failed to decrease the frequency of their cyclic flow variations over the same time period (5.3 +/- 0.3 to 5.0 +/- 0.4 cyclic flow variations per 30-minute period). Twenty-seven dogs had a coronary thrombus induced by a copper coil positioned directly in a major coronary artery; of these, four died of ventricular fibrillation prior to treatment, eight received an infusion of saline and showed no thrombolysis over 5 hours, and three died of ventricular fibrillation during the initial part of an intravenous infusion of ancrod. The remaining 12 dogs received ancrod intravenously (16 U/kg); six demonstrated lysis of the coronary thrombus (mean time to lysis, 65 +/- 20 minutes). The concentrations of ancrod used in these studies produced a severe decrease in systemic fibrinogen concentration and a significant decrease in the inhibitor of plasminogen activator levels. Thus, ancrod decreases the frequency of cyclic flow variations in stenosed canine coronary arteries and may cause coronary thrombolysis in approximately 50% of animals within 65 +/- 20 minutes of its intravenous administration.

Fibrinolysis in health and disease: abnormal levels of plasminogen activator, plasminogen activator inhibitor, and protein C in thrombotic thrombocytopenic purpura.

Thrombotic thrombocytopenic purpura (TTP) is characterized by widespread occluding and persistent microthrombotic lesions. Evidence for both endothelial damage and primary platelet aggregation as possible pathogenetic mechanisms has been produced. Persistence of microthrombi has not been explained satisfactorily. In patients with TTP we studied plasma fibrinolysis and protein C. Tissue plasminogen activator (t-PA) activity levels, measured functionally, were low or unmeasurable in 11 of 12 patients; t-PA antigen levels, measured immunochemically, were normal in all six observed. The level of potent inhibitor of plasminogen activation directed against both t-PA and urokinase was elevated significantly in all 12, whereas the alpha 2-antiplasmin level was elevated in only two. Protein C antigen levels were low in three of six patients observed. Fibrinolysis levels in patients in remission did not differ from those in patients with acute disease. Plasma exchange resulted in temporary reversal of the abnormalities, but achievement of clinical remission was not associated with permanent normalization of fibrinolysis. Inasmuch as all 12 patients had severely depressed fibrinolytic mechanisms it is possible that a defect in the fibrin-clearing system permits thrombus formation to occur and proceed in an unchallenged fashion, thereby contributing to the complex events leading to arterial ischemia in vital organs.

Nephrotic syndrome with renal vein thrombosis: pathogenetic importance of a plasmin inhibitor (alpha 2-antiplasmin).

Tests of fibrinolysis were measured by fibrin plate methods in 44 patients with nephrotic syndrome, in 14 of whom renal vein thrombosis was demonstrated. In both groups the level of total fibrinolytic activity was normal, that of vascular plasminogen activator was decreased, and that of an inhibitor of plasminogen activation was elevated. The level of a plasmin inhibitor, measured by the fibrin plate method, was elevated in 13 of 14 patients with, but only in 12 of 30 without, renal vein thrombosis (p less than 0.005). The plasmin inhibitor was identical with alpha 2-antiplasmin. The data suggest that an increased level of alpha 2-antiplasmin may be a factor in determining susceptibility to the development and persistence of renal vein thrombosis in patients with nephrotic syndrome.

Enhancing effect of dietary supplementation with omega-3 fatty acids on plasma fibrinolysis in normal subjects.

A supplement of MaxEPA oil containing 5 g of omega-3 polyunsaturated fatty acids was given for two weeks to nine normal volunteers. The vascular plasminogen activator (VPA) level increased and there was a fall in the levels of inhibitors of vascular plasminogen activator (IPA) and of plasmin, alpha 2-antiplasmin (alpha 2-AP). No significant changes occur in serum cholesterol, triglycerides, HDL or LDL levels.

Activation of fibrinolysis by apolipoproteins of high density lipoproteins in man.

The effects on fibrinolysis of purified normal human plasma lipoproteins and their apolipoproteins (apo) were assessed in an in vitro system containing urokinase, plasminogen, and fibrin. High and very low density lipoproteins (HDL and VLDL, respectively) but not low density lipoproteins (LDL) significantly increased lysis of radiolabeled fibrin or lysis area of plated fibrin compared to controls. Apo HDL, apo HDL2, apo HDL3, apo VLDL (buffer soluble apo), apo AI and AII activated fibrinolysis by 1.3-1.4 fold of control values, whereas apo B (as a narrow density cut of LDL) and non-lipoprotein control proteins (albumin and myoglobin) did not. Addition of HDL in the absence of urokinase failed to activate fibrin lysis. These data demonstrate that the major proteins of HDL - apo AI and apo AII - and possibly certain minor constituent(s) common to HDL and VLDL participate in the fibrinolytic process.

Ancrod: normalization of fibrinolytic enzyme abnormalities in patients with systemic lupus erythematosus and lupus nephritis.

Ancrod is a thrombinlike enzyme from Malayan pit viper (Agkistrodon rhodostoma) venom that has a selective enzyme substrate specificity for fibrinogen. Unlike thrombin, it splits only fibrinopeptide A from the fibrinogen molecule and does not activate factor XIII. Simultaneously with the occurrence of hypofibrinogenemia there is a reduction of plasma plasminogen and a rise in fibrin degradation products, suggesting secondary recruitment of the fibrinolytic enzyme system. Ancrod was given to 18 patients with systemic lupus erythematosus and glomerular and vascular microthrombi. Before treatment vascular plasminogen activator (VPA) was low or unmeasurable in 14, an inhibitor of urokinase-induced plasminogen activation (IPA) was elevated in 18, and an inhibitor of plasmin (PI) was elevated in five. Ancrod treatment resulted in prompt normalization of IPA levels in 13 patients; they were classified as fibrinolysis responders. In five patients IPA levels remained elevated throughout treatment with ancrod; they were classified as fibrinolysis nonresponders. In these five the PI level was elevated before treatment and decreased slowly toward the normal range during ancrod administration. The PI did not appear related to the nonspecific serine protease inhibitors, and was shown to be identical with alpha 2-antiplasmin. In the fibrinolysis responders serial histologic studies showed a striking decrease of disappearance of microvascular thrombosis; in the fibrinolysis nonresponders microvascular thrombosis persisted. The action of ancrod is discussed.

Lupus nephritis with thrombosis and abnormal fibrinolysis: effect of ancrod.

Recent evidence demonstrates that coagulation plays a role in mediating glomerular damage in patients with systemic lupus erythematosus and diffuse proliferative glomerulonephritis. Because of its beneficial effect in experimental glomerulonephritis, we treated patients with systemic lupus erythematosus and diffuse proliferative glomerulonephritis with ancrod, a drug known to lower fibrinogen levels and thought to activate fibrinolysis. Our patients had unusually severe renal disease; renal function was deteriorating in many. Before ancrod, vascular plasminogen activator levels were low, and levels of an inhibitor of plasminogen activation were elevated. Some patients had elevated plasmin inhibitor levels. Results were considered in two groups. In 13 patients characterized as fibrinolysis responders, the low vascular plasminogen activator and increased plasminogen activation inhibitor levels normalized. After ancrod, striking resolution of microvascular thrombosis occurred, which was associated with some improvement in renal function and blood pressure control. In five patients characterized as fibrinolysis nonresponders and who also had an elevated plasmin inhibitor (alpha 2-antiplasmin) level, normalization of fibrinolysis did not occur. There was little change in microvascular thrombosis, renal function, or blood pressure control in the fibrinolysis nonresponders. These preliminary observations demonstrate a disorder of fibrinolysis in patients with systemic lupus erythematosus with microvascular thrombi in the kidney. Ancrod therapy reverses this disorder rapidly in patients with a normal level of plasmin inhibitor and may lead to repair of glomerular damage.

Fibrinolysis in health and disease: severe abnormalities in systemic lupus erythematosus.

Methods are described to measure fibrinolysis in healthy persons and in patients with systemic lupus erythematosus. Using the fibrin plate method, total fibrinolytic activity and vascular plasminogen activator were measured. (Total fibrinolytic activity expresses the fibrinolytic potential and consists of both the intrinsic [factor XII-dependent and independent] activities and the extrinsic activities [vascular or tissue type]. Vascular plasminogen activator, assessed in a separate assay, refers to the endothelium-derived component only.) In addition, the degree of inhibition by plasma of both urokinase-induced and of plasmin-induced fibrinolysis were analyzed. Vascular plasminogen activator levels were low in 63% of plasma samples from 55 patients with systemic lupus erythematosus. The level of an inhibitor of plasminogen activation was significantly elevated in 87% of patients and levels of an inhibitor of plasmin were significantly elevated in 29%. The nonspecific serine protease inhibitors, including alpha 2-macroglobulin, were within the normal range in all patients. The natures of inhibitor of plasminogen activation and plasmin inhibitor were studied further. Using both the fibrin plate and the lysis time methods, the data indicated that the urokinase-inhibiting activity increased with time of incubation of plasma-enzyme mixtures, whereas the plasmin inhibiting activity did not. Elevated levels of plasmin inhibitor measured with the fibrin plate method correlated well with prolonged lysis times. Results using the chromogenic substrate S-2251, commonly used as a simple and specific assay for antiplasmin, agreed reasonably well with those using the fibrin plate method, but elevated plasmin inhibitor levels could be quantitated with greater accuracy and sensitivity by the fibrin plate method. Studies with an antiserum directed against alpha 2-antiplasmin showed that inhibitor of plasminogen activation and plasmin inhibitor were different inhibitors, and that plasmin inhibitor was identical to alpha 2-antiplasmin. The abnormalities are discussed in the light of current knowledge on fibrinolysis and as possible mediators in the pathogenesis and perpetuation of lupus glomerulonephritis.

Abnormalities of fibrinolysis in essential hypertension.

A highly-standardized plate method was used to study fibrinolytic profiles in 14 patients with essential hypertension and 245 normotensive healthy control subjects. Compared with the normotensive group, the group with essential hypertension showed a defect in fibrinolysis, as evidenced by a significant increase in the mean level of inhibitor of plasminogen activation, and a subset of the hypertensive patients also showed a significant decrease in the mean level of vascular plasminogen activator. There were no significant differences between the two groups in relation to plasma fibrinogen level, total fibrinolytic activity and plasmin inhibitor. The alterations in inhibitor of plasminogen activation and vascular plasminogen activator in the patients with essential hypertension may reflect a defect in the fibrin-clearing mechanism and, perhaps, contribute to the vascular complications of hypertension.