The impact of cardiac ischemia and reperfusion on markers of activated haemostasis and fibrinolysis during cardiopulmonary bypass: comparison of plasma levels in arterial and coronary venous blood

INTRODUCTION: Activation of coagulation and fibrinolysis is common among patients undergoing cardiopulmonary bypass (CPB) surgery. Little is known, however, about the impact of myocardial ischemia and reperfusion on coagulation activation and fibrinolysis in this clinical setting. STUDY DESIGN AND METHODS: We determined the levels of coagulation activation and fibrinolysis markers (CAFM) in 19 patients with severe coronary heart disease (CHD) during CPB surgery. FXIIa, tissue factor (TF), FVIIa, tissue plasminogen activator/plasminogen activator inhibitor-1 complexes (tPA/PAI-1), prothrombin fragments 1+2 (F1+2), D-dimers (DD) and plasmin-plasmin inhibitor complexes (PPI) were measured at baseline, prior to and after cardioplegic myocardial ischemia. Simultaneous blood samples were drawn from the aorta and the coronary sinus to evaluate arteriovenous CAFM plasma level gradients. RESULTS: Myocardial ischemia induced significant increases in gradients of FXIIa and F1+2 levels across the coronary circulation without influencing systemic levels of these markers significantly. Systemic levels of FXIIa, tPA/PAI-1, F1+2, DD and PPI increased significantly during CPB operation. There was a significant linear correlation between FXIIa, FVIIa, F1+2, DD and PPI. CONCLUSIONS: Myocardial ischemia induces contact activation and thrombin generation rather than release of tPA and might thus contribute to postoperative thromboembolic complications. Surgery itself and CPB cause activation of coagulation and fibrinolysis as already described. A significant association between FXIIa, FVIIa, F1+2, DD and PPI suggests a relationship between contact activation, thrombin generation, fibrin formation and fibrinolysis.     

Increased fibrinolytic activity during use of oral contraceptives is counteracted by an enhanced factor XI-independent down regulation of fibrinolysis: a randomized cross-over study of two low-dose oral contraceptives

The effect of oral contraceptives (OC) on fibrinolytic parameters was investigated in a cycle-controlled cross-over study in which 28 non-OC using women were randomly prescribed either a representative of the so-called second (30 microg ethinylestradiol, 150 microg levonorgestrel) or third generation OC (30 microg ethinylestradiol, 150 microg desogestrel) and who switched OC after a two month wash out period. During the use of OC, the levels of tissue-type plasminogen activator (tPA) activity, plasminogen, plasmin-alpha2-antiplasmin complexes and D-dimer significantly increased (by 30 to 80%), while the levels of plasminogen activator inhibitor- (PAI-1) antigen, PAI-1 activity and tPA antigen significantly decreased (25 to 50%), suggesting an increase in endogenous fibrinolytic activity. These OC-induced changes were not different between the two contraceptive pills. TAFI (thrombin-activatable fibrinolysis inhibitor) levels increased on levonorgestrel, and even further increased on desogestrel. A clot lysis assay that probes both fibrinolytic activity and the efficacy of the coagulation system to generate thrombin necessary to down regulate fibrinolysis via TAFI showed no change of the clot lysis time during OC use. This finding suggests that the OC-induced increase in endogenous fibrinolytic activity is counteracted by an increased capacity of the coagulation system to down regulate fibrinolysis via TAFI. Indeed we observed that during OC use there was a significant increase of F1+2 generation during clot formation. When these assays were performed in the presence of an antibody against factor XI, we observed that the clot lysis time was significantly increased during OC use and that the increase in F1+2 generation during OC therapy was due to a factor XI-independent process, which was significantly higher on desogestrel than on levonorgestrel. These data indicate that the OC-induced inhibition of endogenous fibrinolysis takes place in a factor XI-independent way and is more pronounced on desogestrel than on levonorgestrel-containing OC.     

Improved fibrinolysis after 1-year treatment with HMG CoA reductase inhibitors in patients with coronary heart disease

The study was aimed to investigate the effect of two different statins on the levels of haemostatic variables reflecting procoagulant and fibrinolytic activity in patients with coronary heart disease (CHD), with the hypothesis that statins might beneficially modify these levels. Fifty-eight patients were randomized to treatment with atorvastatin (n=28) or simvastatin (n=30) for 1 year. The starting dose in both groups was 20 mg/day. Fasting blood samples were collected before and after 12-month treatment for determinations of fibrinogen, prothrombin fragment 1+2 (F1+2), plasma D-dimer, soluble tissue factor, tissue plasminogen activator (tPA) antigen, tPA activity, plasminogen activator inhibitor type-1 activity (PAI-1 activity) and serum D-dimer as a global test of fibrinolytic activity. In the total population, improved fibrinolytic activity was observed after 1 year with increased levels of serum D-dimer (P=.001) and tPA activity (P=.024) and a reduction in tPA antigen (P=.048). No statistically significant changes were observed in any of the measured coagulation variables. Separately examined, an improved fibrinolytic profile was seen in the atorvastatin group with a significant increase in serum D-dimer (P=.005), a borderline increase in tPA activity (P=.083) and a borderline reduction in tPA antigen (P=.069). Within the simvastatin group, a reduction in prothrombin F1+2 was observed (P=.038). The differences in changes between the groups were statistically significant only for global fibrinolysis (serum D-dimer, P=.046). In conclusion, an improved fibrinolytic profile was observed after statin treatment, most pronounced with atorvastatin. The results indicate that the drugs promote a profibrinolytic profile, and may in part explain the benefit of statin treatment rendered in the prevention of CHD.     

Markers of coagulation and fibrinolysis after fractures of the lower extremities.

The study was performed to detect activation of coagulation and fibrinolysis in terms of prothrombin fragment 1 and 2 (F1 + 2), thrombin-antithrombin III complex (TAT), fibrin degradation products (FbDP), fibrinogen degradation products (FgDP), and soluble fibrin monomers (FM) in plasma from 39 patients with fractures of the lower extremities. We found substantially elevated levels of the molecular markers at admission and on the day after admission (Day 1) compared with control levels. Admission levels of F1 + 2, TAT, FbDP and FgDP were significantly higher compared with levels on day 1, whereas levels of FM were not significantly different between the two days. Generally there were good correlations between all markers of coagulation and fibrinolysis at admission whereas correlations were weaker or absent on day 1. In conclusion we found substantial haemostatic activation as a immediate response to trauma. Increased levels of F1 + 2, TAT, FM, FbDP and FgDP appear to be a normal physiological reaction after fractures of the lower extremities.     

Coagulation and fibrinolysis after open infrarenal abdominal aortic aneurysm repair in a long-term perspective

In patients with abdominal aortic aneurysms (AAA) the coagulation and fibrinolytic systems have been found to be activated preoperatively. Does the increased activity of the coagulation and fibrinolytic systems persist after AAA surgery in a long-term perspective? Prothrombin fragment 1+2 (F1+2), thrombin-antithrombin complex (TAT), tissue plasminogen activator (tPA), human plasminogen activator inhibitor type 1, and human cross-linked fibrin degradation product (D-dimer) were analysed in 18 patients after open AAA surgery (postop-AAA). The median time between surgery and blood sampling was 19 months (range, 5-37 months). Comparisons were made with both preoperative values of 23 patients with AAA (preop-AAA) as well as 20 age-matched healthy controls (AMC). F1+2, TAT, and D-dimer in preop-AAA were significantly higher compared to AMC (p<0.001). In post-op AAA patients these parameters were significantly lower compared to preop-AAA (p<0.05 for F1+2 and TAT, p<0.001 for D-dimer). However, TAT and D-dimer levels were still higher in postop-AAA than in AMC (p<0.01 for both). The activity of the coagulation and fibrinolytic systems seems to decrease after AAA surgery. However, the activity is still higher than in healthy AMC. A possible explanation may be that the thrombogenicity is lower in a vascular graft than in an aneurysmal sac but still higher than in a nonaneurysmal aorta.     

Sequential intrapulmonary and systemic activation of coagulation and fibrinolysis during and after total hip replacement surgery

Hip joint replacement surgery, using acrylic cement for prosthesis fixation, is associated with intraoperative cardiorespiratory dysfunction, and a high frequency of postoperative proximal deep vein thrombosis (DVT). Levels of prothrombin fragments ₁₊₂ (F₁₊₂), tissue plasminogen activator antigen (t-PA), plasminogen activator inhibitor 1 activity (PAI-1), D-dimer and interleukin 6 (IL-6) were measured in arterial (AB) and mixed venous blood (MVB) in five patients during and after total hip replacement operation with acrylic cement prosthesis fixation. Sequential peaks of F₁₊₂, t-PA, PAI-1 and IL-6 appeared, starting with activation of coagulation during preparation of bone, closely followed by activation of fibrinolysis. Later, this was counteracted by an antifibrinolytic response and increase of IL-6. After a fibrinolytic shutdown on the third postoperative day as evidenced by a drop in t-PA and D-dimer concentrations, a second wave of coagulation was seen at the end of the first week. The present model, with frequent sampling of blood entering and leaving the lungs, confirms our earlier findings of the lung as a key organ in promoting coagulation following traumatic activation.     

Effects of recombinant plasminogen activator inhibitor type 1 on fibrinolysis in vitro and in vivo

A biologically active recombinant PAI-1 (rPAI-1) was evaluated for its effects on clot lysis in vitro and in vivo. At concentrations of 0.5 to 10 micrograms/ml, the rPAI-1 significantly prolonged the time to lysis of rabbit euglobulin clots both in the presence and absence of exogenous tissue plasminogen activator. To examine the effects of PAI in vivo, we infused rPAI-1 into conscious rabbits after i.v. injection of homogenized fibrin clots, and assessed fibrinolysis by measuring the appearance of d-dimer fibrin degradation products (FDP). Plasma fibrinolytic activity, PAI activity and antigen were also measured in plasma samples taken during and after infusion of rPAI-1. In control rabbits, endogenous fibrinolytic activity resulted in a significant and continual generation of FDP, reaching 32.6 +/- 13.6 ng/ml 90 minutes after fibrin injection. Infusion of 1, 2, or 5 micrograms/kg/min rPAI-1 led to dose dependent increases in PAI activity and antigen, while FDP levels at 90 minutes were only 8.8 +/- 2.9, 5.7 +/- 2.4, and 0.3 +/- 0.3 ng/ml, respectively. Complete inhibition of fibrinolysis was observed with 10 micrograms/kg/min rPAI-1. These studies directly demonstrate that increases in PAI-1 impair the fibrinolytic system, and support indirect observations of an association between elevated levels of this protein and thromboembolic diseases.     

The potentiating effect of platelet on plasminogen activation by tissue plasminogen activator

A new role for platelets in fibrinolysis is proposed. Platelets (euglobulin from platelet rich plasma and from human platelet extract) may potentiate plasminogen activation by tissue plasminogen activator(tPA). The potentiating activity was detected by both chromogenic substrate and fibrin plate analysis. The fibrinolysispotentiating substance in the platelets required the presence of both tPA and plasminogen, suggesting that it potentiates the activation of plasminogen by tPA. This substance was not related to fibrinogen degradation products because it was also present in platelets from two afibrinogenemic patients and did not lose its activity when separated from fibrinogen-related antigen by Sepharose 2B gel filtration. Since platelets contain both activator(s) and inhibitor(s) of plasminogen activation by tPA, a balance between activator(s) and inhibitor(s) in platelets may also be required for control of the fibrinolytic pathway.     

Increased blood fibrinolytic activity after physical exercise: comparative study in individuals with different sporting activities and in patients after myocardial infarction taking part in a rehabilitation sports program

The activation of fibrinolysis during bicycle ergometry was studied in two pairs of age-matched groups. Group A: 18 healthy male competitive athletes (23 +/- 3.5 years of age, mean +/- SD), Group B: 18 healthy male volunteers (25.7 +/- 2.7) not engaged in any sports, Group C: 17 healthy male volunteers (50.6 +/- 7.7) regularly practicing sports, and Group D: 18 male survivors from myocardial infarction (MI-patients, 54.2 +/- 7.9) who took part in a rehabilitation sports program. Before ergometry, healthy participants with regular sporting activities showed significantly lower plasma plasminogen activator inhibitor capacities (PAI cap) than the members of the respective age-matched control groups: Group A 13.9 +/- 2.6 AU/ml, Group B 18.5 +/- 5.5, p less than 0.005; Group C 15.2 +/- 2.9, Group D 20.7 +/- 5.5, p less than 0.05. During ergometry the release of tPA antigen did not differ significantly between the age-matched groups, however, tissue plasminogen activator (tPA) activities after ergometry were higher in groups presenting lower pre-test PAI cap values. Group A 5.5 +/- 6.4 AU/ml, Group B 1.1 +/- 2.9 AU/ml, p less than 0.05; Group C 2.9 +/- 3.3, Group D 0.2 +/- 0.7, p less than 0.05. Levels of the fibrin split product (D-dimer) did not change in any of the groups. This investigation indicates that (1) regular vigorous sporting activities enhance blood fibrinolysis by reducing blood PAI cap in healthy individuals, (2) rehabilitation sport is not capable of reducing blood PAI cap in MI-patients to values measured in age matched healthy individuals regularly practicing sports and (3) the activation of fibrinolysis during physical exercise has no systemic fibrinolytic effect.     

Effects of oral and transdermal estrogen replacement therapy on markers of coagulation, fibrinolysis, inflammation and serum lipids and lipoproteins in postmenopausal women

We compared the effects of oral estradiol (2 mg), transdermal estradiol (50 microg), and placebo on measures of coagulation, fibrinolysis, inflammation and serum lipids and lipoproteins in 27 postmenopausal women at baseline and after 2 and 12 weeks of treatment. Oral and transdermal estradiol induced similar increases in serum free estradiol concentrations. Oral therapy increased the plasma concentrations of factor VII antigen (FVIIag) and activated factor VII (FVIIa), and the plasma concentration of the prothrombin activation marker prothrombin fragment 1+2 (F1+2). Oral but not transdermal estradiol therapy significantly lowered plasma plasminogen activator inhibitor-1 (PAI-1) antigen and tissue-type plasminogen activator (tPA) antigen concentrations and PAI-1 activity, and increased D-dimer concentrations, suggesting increased fibrinolysis. The concentration of soluble E-selectin decreased and serum C-reactive protein (CRP) increased significantly in the oral but not in the transdermal or placebo groups. In the oral but not in the transdermal or placebo estradiol groups low-density-lipoprotein (LDL) cholesterol, apolipoprotein B and lipoprotein (a) concentrations decreased while high-density-lipoprotein (HDL) cholesterol, apolipoprotein AI and apolipoprotein All concentrations increased significantly. LDL particle size remained unchanged. In summary, oral estradiol increased markers of fibrinolytic activity, decreased serum soluble E-selectin levels and induced potentially antiatherogenic changes in lipids and lipoproteins. In contrast to these beneficial effects, oral estradiol changed markers of coagulation towards hypercoagulability, and increased serum CRP concentrations. Transdermal estradiol or placebo had no effects on any of these parameters. These data demonstrate that oral estradiol does not have uniformly beneficial effects on cardiovascular risk markers and that the oral route of estradiol administration rather than the circulating free estradiol concentration is critical for any changes to be observed.     

Tissue plasminogen activator and plasminogen activator inhibitor in patients with acute ischemic stroke: relation to stroke etiology

Recent studies suggest that high plasma levels of tissue-type plasminogen activator (tPA) and its inhibitor (plasminogen activator inhibitor-1, PAI-1) are markers of an increased risk of atherothrombotic ischemic events such as stroke and myocardial infarction. In this prospective study, we measured tPA antigen, PAI-1 antigen and activity, as well as tPA/PAI-1 complex in patients with acute stroke. Stroke subtypes were classified according to the TOAST criteria. From 132 consecutively screened patients, 89 (100%) were enrolled in this study, including 42 patients (47%) with large artery atherosclerosis (LAA), 32 (36%) with small vessel occlusion (SVO), and 15 (17%) with cardioembolism (CE). Nineteen age-matched neurologic patients without manifestations of cerebrovascular disease served as control subjects (CS). Patients with acute stroke had significantly higher plasma levels of tPA antigen (p < 0.001), PAI-1 antigen (p < 0.05) and PAI activity (p < 0.05) than patients in the control group. t-PA antigen, PAI activity and tPA/PAI-1 complex levels were similar regardless of stroke etiology. Only PAI-1 antigen was lower in patients with cardioembolic stroke than in stroke patients with LAA (p < 0.05). Plasma tPA antigen, PAI-1 antigen, and PAI activity are significantly increased in patients with acute ischemic stroke. Except for PAI-1 antigen, this increase appears not to be related to the underlying stroke etiology.     

Blood coagulation and fibrinolysis after extreme short-term exercise

Introduction: Maximal exercise may be a trigger for cardiovascular events. The aim of the study was to investigate changes in blood coagulation and fibrinolysis following maximal short-term exercises with different durations up to 90 s. Methods: A total of 15 healthy nonsmokers underwent three isokinetic maximal tests on an SRM cycle ergometry system with durations of 15, 45, and 90 s. Blood samples were taken after a 30-min rest, immediately before and after exercise, 15 min, and 1 h after completion of exercise. For the investigation of blood coagulation, prothrombin fragment 1+2 (F1+2), thrombin–antithrombin III complex (TAT), intrinsic and extrinsic total (TTPin+ex), and endogenous thrombin potential (ETPin+ex) were measured. For testing fibrinolysis, determinations of plasmin-₂-antiplasmin complex (PAP), tissue-type plasminogen activator (tPA)-antigen, plasminogen activator inhibitor (PAI)-1-antigen and -dimer were used. Results: Immediately after the exercise tests, only F1+2 (15- and 90-s test) and TTPin (45 and 90 s) showed a moderate increase (p<0.05), while TAT and ETP was unchanged. In contrast, a clear increase in PAP and tPA-antigen already after 15 s maximal exercise in relation to the exercise duration time could be investigated. These effects were not totally reversed to baseline 15 min after exercise; -dimer and PAI-1-antigen still remained unchanged after these types of exercise. Conclusions: Maximal short-term exercise does not lead to a relevant activation of blood coagulation in healthy young subjects, it is only slightly altered within the normal range. In contrast, fibrinolysis is clearly activated, and the increase is directly dependent on exercise duration. Additionally, it could be shown for the first time that fibrinolysis is already activated after 15 s maximal exercise duration.     

THE EFFECT OF PHYSICAL CONDITIONING SUGGESTS ADAPTATION IN PROCOAGULANT AND FIBRINOLYTIC POTENTIAL

Acute exercise evokes a transient increase in procoagulant activity. We evaluated the effect of physical conditioning on the activation of the coagulation and fibrinolytic systems. Two groups of subjects of different aerobic endurance levels (athletes and controls with maximal oxygen uptake (VO_{2 max}) 68,4 and 52,6 ml·kg⁻¹·min⁻¹, respectively), were tested at rest and after standardized exercise at 80 % of their individual VO_{2 max}. There was a significant increase in prothrombinfragment 1+2 (F1+2) level among controls in response to standardized exercise (p<0.05), whereas no significant difference in the level of F1+2 between athletes and controls at rest or in response to exercise was demonstrated. Tissue plasminogen activator (tPA) antigen level at rest was significantly lower in athletes compared to controls (p<0.03). A significant increase was found in the tPA level after standardized exercise in both groups (p<0.02), which was lower in athletes compared to controls (p<0.05). There were no significant differences between athletes and controls in plasminogen activator inhibitor-1 (PAI-1) and thrombin antithrombin complex (TAT) levels at rest. Athletes had a significantly lower PAI-1 level than controls after exercise (p<0.05). In conclusion, the present study suggests an increased activation of the coagulation system in response to exercise in controls only. It also suggests adaptive changes in fibrinolytic potential induced by physical conditioning, as demonstrated by the lower level of tPA at rest and the lower levels of tPA and PAI-1 after exercise in athletes compared to controls. © 1997 Elsevier Science Ltd     

Serial changes in fibrinolysis and coagulation activation markers in acute and convalescent phase of ischemic stroke

BACKGROUND: The changes in the activity of a number of plasma markers of coagulation and fibrinolysis have previously been studied in patients with ischemic stroke, with conflicting results. We aimed to find out the changes in the activities of a wide array of markers of the coagulation and the fibrinolytic system of mildly or moderately affected first-ever ischemic stroke patients. METHODS: In a prospective, longitudinal, case-control study, we studied plasma plasminogen activator inhibitor type-1 (PAI-1) activity, tissue-type plasminogen activator antigen (t-PA:Ag), d-dimer, prothrombin fragment 1+2 (F 1+2), and thrombin-antithrombin III complex (TAT) levels in 55 consecutive patients on admission, 1 week, 1 month, and 3 months after an ischemic stroke. Sex- and age-matched controls were studied once. All patients underwent blood sampling at each study time point; comprehensive stroke risk factors were recorded, and the etiology of the ischemic stroke was determined. All patients were contacted 3 years later for possible recurrent ischemic events. RESULTS: PAI-1 activity was increased in the acute phase and at 3 months, D-dimer levels were significantly higher at 1 week and 1 month after stroke, whereas t-PA:Ag, TAT and F 1+2 levels remained stable during the whole study period. CONCLUSIONS: The changes of the fibrinolytic and coagulation system activity in the patients with mild or moderate ischemic stroke appeared minor compared with the results of previous studies, which included more severely ill patients.     

Hemostatic alterations in patients with benign and malignant colorectal disease during major abdominal surgery.

We determined sensitive markers of coagulation and fibrinolysis in plasma of 20 patients with malignant colorectal disease as compared to 17 patients with benign colorectal disease. Thrombin/antithrombin III complex (TAT), soluble fibrin (SF), total fibrinogen and fibrin degradation products (TDP), plasminogen activator inhibitor type-1 (PAI-1), urokinase-type plasminogen activator (uPA) and uPA receptor (uPAR) were measured preoperatively, starting anesthesia, during surgery and postoperatively. The purpose was to verify the supposed hypercoagulable state of cancer patients. In addition, we investigated whether the hemostatic alterations induced by general anesthesia and major abdominal surgery differed between the two groups. Patients with colorectal cancer showed initially an altered balance of hemostasis with a preponderance of procoagulant activity and fibrinolytic inhibition, as noted by marginally elevated TAT and PAI-1 plasma levels. The stimulus of anesthesia induction alone was sufficient to trigger not only activation of coagulation in these patients but also further activation of fibrinolysis and increased fibrinolytic inhibition. The marked activation of coagulation and fibrinolysis and enhanced fibrinolytic inhibition during surgery was more pronounced in patients with malignancy as compared to the control group. Postoperatively, a shift of the normal balance of hemostasis with a slight preponderance of fibrinolytic inhibition was observed, as evidenced by a marginally elevated PAI-1 plasma levels. The results of this study strengthen the hypothesis of a hypercoagulable state in patients with colorectal malignancy that may favor the development of thrombosis in this patient group.     

Short-term effect of surgical trauma on rat peritoneal fibrinolytic activity and its role in adhesion formation

BACKGROUND: Fibrin deposition, the primary step in the formation of post-surgical adhesions, is the result of a disbalance between the fibrin-forming and the fibrin-dissolving capacity of the peritoneum. Literature data suggest a transient reduction in local plasminogen activator activity after peritoneal trauma, which results in a reduction of fibrinolysis and permits deposited fibrin to become organized into fibrous, permanent adhesions. In the present study, the fibrinolytic parameters tissue-type plasminogen activator (tPA; antigen and activity) and plasminogen activator inhibitor type-1 (PAI-1; antigen and activity) were measured in peritoneal fluid, in peritoneal biopsies and in plasma to establish the time course of changes in fibrinolytic activity. DESIGN: A standardized peritoneal adhesion model in the rat. OUTCOME MEASURES: Analysis, over a 72-h period following surgical trauma. of the main fibrinolytic parameters in peritoneal lavage, in biopsies of damaged and undamaged peritoneum, and in plasma, and determination of fibrin and fibrin(ogen)-degradation products in peritoneal lavage fluid. RESULTS: At all time intervals, tPA antigen was found to be about six-fold increased in peritoneal lavage after surgical trauma. This significant rise in tPA antigen was accompanied by a large increase in its main inhibitor PAI-1, resulting in tPA activity levels similar to, or slightly higher than, those found in control animals. tPA activity was lowest at 4 h and increased thereafter. Also in biopsies from damaged peritoneum, tPA antigen was significantly increased. Tissue tPA activity was also lowest at 4 h, after which it increased, significantly so at 24 and 72 h. Similar, though smaller, changes were seen in the biopsies from undamaged areas of the peritoneal wall in operated rats. PAI-1 (antigen and activity) was not detected in peritoneal biopsies. Fibrin-related material (especially fibrin monomer/fibrinogen, an indicator of forming fibrin) in peritoneal fluid was slightly increased at 4 h, and abundantly present at 16 and 24 h, returning to control levels at 72 h. Fibrin degradation products were always present. From 2 h onward, adhesions were found. CONCLUSIONS: In contrast to the view that adhesions are formed as a result of a reduced fibrinolytic activity, our results demonstrate that tPA activity remained unchanged or slightly increased after surgical trauma, and point to increased fibrin formation rather than diminished fibrinolytic activity as the main cause of fibrin deposition after peritoneal trauma. Therapies directed at prevention of adhesion formation should therefore aim at avoiding massive fibrin production and at promoting fibrinolytic activity during the early period after trauma.     

Hypofibrinolysis associated with vasculopathy in non insulin dependent diabetes mellitus

The pathogenesis of diabetic vasculopathy has been related to modifications in hemostasis and fibrinolysis. 50 non insulin dependent diabetes mellitus patients have been studied. Euglobulin clot lysis time, fibrin plate, tissue plasminogen activator (t-PA) antigen, plasminogen activator inhibitor (PAI) activity, Protein C and S, cholesterol, triglycerides and Hb A1c were determined in blood samples. Diabetic patients showed decreased fibrinolytic activity, as measured by ECLT, with clearly increased PAI levels. Fibrinolytic response to venous occlusion was lower than normal. Vascular complications were associated both with an even higher PAI activity and with a decreased fibrinolytic response to venous occlusion. Elevated PAI activity and decreased fibrinolytic response to stimulus may contribute to vascular disease in diabetes.     

血浆中PAI-1和TAFI水平与溶栓后出血性转化相关性研究

目的探索PAI及TAFI对急性脑梗死静脉溶栓后出血性转化的预警作用。方法前瞻性的将溶栓患者分为出血转化组和无出血转化组,对两组患者溶栓前及溶栓后静脉血浆PAI及TAFI浓度进行对比及统计学分析。结果溶栓前两组基线PAI-1水平差异有明显统计学意义(P=0.037)。溶栓后次日复查晨血PAI-1水平出血转化组明显较无出血转化组值更低(P=0.035)。溶栓前出血转化组的基线TAFI水平较无出血转化组比较TAFI值更低(P=0.024)。溶栓后次日复查晨血出血转化组TAFI值同样低于无出血转化组(P=0.042)。结论血浆中PAI-1和TAFI水平与溶栓后出血性转化相关性较高。当溶栓前及溶栓后PAI-1及TAFI的低水平表达均可增加溶栓后出血性转化的风险。     

Association of the fibrinolytic system and hemorheology with symptoms in patients with carotid occlusive disease

BACKGROUND AND OBJECTIVES: The risk of stroke caused by a symptomatic high-grade carotid stenosis (CS) is high. Disturbed balance between the procoagulant and fibrinolytic activity in blood associated with unfavorable hemorheology could render CS symptomatic. We wanted to assess whether hemostatic and fibrinolytic plasma markers as well as basic indicators of hemorheology differentiate asymptomatic and symptomatic patients with a high-grade CS and whether they are associated with the macroscopic appearance of the plaque and the rate of microembolization. METHODS: We recruited 92 consecutive consenting patients referred to the neurological or the surgical department of our university teaching hospital for treatment of their high-grade CS. Blood samples were collected before surgery for determination of prothrombin fragments F1 and 2, thrombin-antithrombin complex, tissue-type plasminogen activator (tPA) activity and antigen, plasminogen activator inhibitor-1 (PAI-1) activity and antigen, D-dimer, homocysteine, fibrinogen, in plasma, and hematocrit in blood, and the patients underwent transcranial Doppler ultrasonology for evaluation of microembolic signals (MES). RESULTS: Patients with symptomatic plaques had higher hematocrit levels (p = 0.04), as well as trends for higher tPA antigen and MES rate (p = 0.07). Hematocrit, tPA antigen, and PAI-1 antigen and activity were positively correlated with the degree of stenosis. Ulceration was more common in symptomatic plaques but did not reflect variables of hemostasis or fibrinolysis. In multivariate analysis, tPA antigen and hematocrit were risk factors for a symptomatic high-grade stenosis. CONCLUSION: Mediators of fibrinolysis and unfavorable hemorheology may contribute to the development of a symptomatic disease in patients with a high-grade CS.     

Bispecific monoclonal antibodies produced by somatic cell fusion increase the potency of tissue plasminogen activator

Bispecific monoclonal antibodies that bind simultaneously to human fibrin and tissue plasminogen activator (tPA) enhance the fibrinolytic potency of tPA. Two bispecific antibodies (F36.23 and F32.1) were generated by somatic cell fusion. Antibody F36.23 derives its tPA binding from monoclonal anti-tPA antibody TCL8 and its fibrin binding from monoclonal antifibrin antibody 59D8. After purification from cell supernatants and ascites by two steps of affinity chromatography, hybrid-hybridoma bispecific antibody F36.23 simultaneously bound tPA and fibrin in solution and in solid-phase assays. In an assay for the lysis of human fibrin monomer, F36.23 increased the fibrinolytic potency of tPA by 5 to 10 fold, regardless of whether the bispecific antibody had been combined with the tPA before or during the assay. Bispecific F36.23 F(ab')2 also bound tPA and fibrin simultaneously, and the enhancement in fibrinolysis in the presence of F36.23 F(ab')2 was identical to that in the presence of intact F36.23. The second bispecific antibody, F32.1, was produced by an alternative strategy that has a wider potential for application in other systems. Hybridoma bispecific antibody F32.1 was derived from the fusion of immune splenocytes (in mice immunized with a synthetic oligopeptide representing the amino terminus of the alpha-chain of human fibrin) with the anti-tPA cell line TCL8. The properties of hybridoma bispecific antibody F32.1 and its F(ab')2 were indistinguishable from those of hybrid-hybridoma bispecific antibody F36.23 in solid-phase binding assays and in assays of fibrinolysis. Bispecific antibodies produced by somatic cell fusion, particularly in the form of F(ab')2, may have potential for use in clinical thrombolysis.