An evaluation of the euglobulin method for the determination of fibrinolysis

Development of a Methodology Based on Optical Interferometry for Measuring Fibrinolytic Activity

Fibrinolytic activity assay is particularly important for the detection, diagnosis, and treatment of cardiovascular disease and the development of fibrinolytic drugs. A novel efficacious strategy for real-time and label-free dynamic detection of fibrinolytic activity based on ordered porous layer interferometry (OPLI) was developed. Fibrin or a mixture of fibrin and plasminogen (Plg) was loaded into the highly ordered silica colloidal crystal (SCC) film scaffold to construct a fibrinolytic response interference layer to measure fibrinolytic activity with different mechanisms of action. Fibrinolytic enzyme-triggered fibrinolysis led to the migration of interference fringes in the interferogram, which could be represented by optical thickness changes (ΔOT) tracked in real time by the OPLI system. The morphology and optical property of the fibrinolytic response interference layer were characterized, and the Plg content in the fibrinolytic response interference layer and experimental parameters of the system were optimized. The method showed adequate sensitivity for the fibrinolytic activity of lumbrokinase and streptokinase, with wide linear ranges of 12-6000 and 10-2000 U/mL, respectively. Compared with the traditional fibrin plate method, it has a lower detection limit and higher linearity. The whole kinetic process of fibrinolysis by these two fibrinolytic drug models was recorded in real time, and the Michaelis constant and apparent kinetic parameters were calculated. Importantly, some other blood proteins were less interfering with this system, and it showed reliability in fibrin activity detection in real whole blood samples. This study established a better and more targeted research method of in vitro fibrinolysis and provided dynamic monitoring data for the analysis of fibrinolytic activity of whole blood.

Methods, precision, and analytical sensitivity of a novel low-plasma-volume assay of fibrinolytic capacity utilizing the euglobulin fraction

INTRODUCTION

Fibrinolysis is a critical aspect of the hemostatic system, with assessment of fibrinolytic potential being critical to predict bleeding and clotting risk. We describe the method for a novel low-plasma-volume assay of fibrinolytic capacity utilizing the euglobulin fraction (the "modified mini-euglobulin clot lysis assay [ECLA]"), its analytic sensitivity to alterations in key fibrinolytic substrates/regulators, and its initial applications in acute and convalescent disease cohorts.

METHODS

The modified mini-ECLA requires 50 μL of plasma, a maximal read time of 3 h (with most results available within 60 min), and is entirely performed in a 96-well microplate. Assay measurements were obtained in a variety of commercial control and deficient plasmas representing clinically relevant hypo- and hyperfibrinolytic states, and in three distinct adolescent cohorts with acute or convalescent illness: critically ill, following endotracheal intubation; acute COVID-19-related illness; and ambulatory, 3 months following a venous thromboembolic event.

RESULTS

In 100% and 75% deficient plasmas, hypofibrinolysis for plasminogen-deficient, fibrinolysis for alpha-2-antiplasmin-deficient, and hyperfibrinolysis for plasminogen activator inhibitor-1-deficient plasmas were observed.

CONCLUSION

The modified mini-ECLA Clot Lysis Time Ratio ("CLTR") demonstrated moderate-strength correlations with the Clot Formation and Lysis (CloFAL) assay, is analytically sensitive to altered fibrinolytic states in vitro, and correlates with clinical outcomes in preliminarily-studied patient populations.

Utility of Global Hemostatic Assays in Patients with Bleeding Disorders of Unknown Cause

Bleeding disorder of unknown cause (BDUC) is a diagnosis of exclusion after exhaustive evaluation of plasmatic coagulation and platelet function. This review explores the utility of global hemostatic assays as confirmatory tests and in elucidating the pathophysiology of BDUC. Unlike traditional hemostatic tests that focus on coagulation factors, global assays are conducted both in plasma and also whole blood. These assays provide a more comprehensive understanding of the cell-based model of coagulation, aid in the identification of plasmatic factor abnormalities that may reduce hemostatic capacity, and allow for the assessment of impaired platelet-endothelial interactions under shear stress, as well as hyperfibrinolytic states. While clinical tests such as skin bleeding time and global assays such as PFA-100 exhibit limited diagnostic capacity, the role of viscoelastic testing in identifying hemostatic dysfunction in patients with BDUC remains unclear. Thrombin generation assays have shown variable results in BDUC patients; some studies demonstrate differences compared with healthy controls or reference values, whereas others question its clinical utility. Fibrinolysis assessment in vitro remains challenging, with studies employing euglobulin clot lysis time, plasma clot lysis time, and fluorogenic plasmin generation yielding inconclusive or conflicting results. Notably, recent studies suggest that microfluidic analysis unveils shear-dependent platelet function defects in BDUC patients, undetected by conventional platelet function assays. Overall, global assays might be helpful for exploring underlying hemostatic impairments, when conventional hemostatic laboratory tests yield no results. However, due to limited data and/or discrepant results, further research is needed to evaluate the utility of global assays as screening tools.

Viscoelastic monitoring in trauma resuscitation

BACKGROUND

Traumatic injury results in both physical and physiologic insult. Successful care of the trauma patient depends upon timely correction of both physical and biochemical injury. Trauma-induced coagulopathy is a derangement of hemostasis and thrombosis that develops rapidly and can be fatal if not corrected. Viscoelastic monitoring (VEM) assays have been developed to provide rapid, accurate, and relatively comprehensive depictions of an individual's coagulation profile. VEM are increasingly being integrated into trauma resuscitation guidelines to provide dynamic and individualized guidance to correct coagulopathy.

STUDY DESIGN AND METHODS

We performed a narrative review of the search terms viscoelastic, thromboelastography, thromboelastometry, TEG, ROTEM, trauma, injury, resuscitation, and coagulopathy using PubMed. Particular focus was directed to articles describing algorithms for management of traumatic coagulopathy based on VEM assay parameters.

RESULTS

Our search identified 16 papers with VEM-guided resuscitation strategies in adult patients based on TEG, 12 such protocols in adults based on ROTEM, 1 protocol for children based on TEG, and 2 protocols for children based on ROTEM.

CONCLUSIONS

This review presents evidence to support VEM use to detect traumatic coagulopathy, discusses the role of VEM in trauma resuscitation, provides a summary of proposed treatment algorithms, and discusses pending questions in the field.

Euglobulin clot lysis time reveals a high frequency of fibrinolytic activation in trauma

Activation of the fibrinolytic system plays a central role in the host response to trauma. There is significant heterogeneity in the degree of fibrinolysis activation at baseline that is usually assessed by whole blood thromboelastography (TEG). Few studies have focused on plasma markers of fibrinolysis that could add novel insights into the frequency and mechanisms of fibrinolytic activation in trauma. Global fibrinolysis in plasma was assessed using a modified euglobulin clot lysis time (ECLT) assay in 171 major trauma patients and compared to commonly assessed analytes of fibrinolysis. The median ECLT in trauma patients was significantly shorter at 8.5 h (IQR, 1.3-19.5) compared to 19.9 h (9.8-22.6) in healthy controls (p < 0.0001). ECLT values ≤2.5th percentile of the reference range were present in 83 (48.5%) of trauma patients, suggesting increased fibrinolytic activation. Shortened ECLT values were associated with elevated plasmin-antiplasmin (PAP) complexes and free tissue plasminogen activator (tPA) levels in plasma. Sixteen (9.2%) individuals met the primary outcome for massive transfusion, here defined as the critical administration threshold (CAT) of 3 units of packed red cells in any 60-minute period within the first 24 h. In a univariate screen, plasma biomarkers associated with CAT included D-dimer (p < 0.001), PAP (p < 0.05), free tPA (p < 0.05) and ECLT (p < 0.05). We conclude that fibrinolytic activation, measured by ECLT, is present in a high proportion of trauma patients at presentation. The shortened ECLT is partially driven by high tPA levels and is associated with high levels of circulating PAP complexes. Further studies are needed to determine whether ECLT is an independent predictor of trauma outcomes.

Comparison of Hemostatic Disturbances between Patients on Capd and Patients on Hemodialysis

Objective

Disturbances in hemostasis are common findings in uremic patients. Both bleeding diathesis and thrombosis are observed. The purpose of this study was to assess whether renal replacement therapy in the form of hemodialysis (HD) or continuous ambulatory peritoneal dialysis (CAPD) affects coagulation and fibrinolysis in patients with end-stage renal failure.

Design

Comparison of hemostatic measures in patients on CAPD, HD, and matched healthy controls.

Setting

Department of Nephrology and Internal Medicine, Bialystok University School of Medicine.

Patients and Methods

Twenty-four HD patients and 23 CAPD patients were evaluated with respect to platelet aggregation, hemostatic parameters, serum lipids, lipoprotein(a), and cytokines [tumor necrosis factor alpha (TNFα) and interleukin-1 (IL-1)].

Interventions

Four exchanges of CAPD per day, using 2.0 L dialysate over a period of 25 ± 31 months; or 4 – 5 hours of HD 3 times per week for a period of 31 ± 22 months.

Results

Platelet aggregation in whole blood and platelet-rich plasma was significantly impaired in both groups of dialyzed patients compared to healthy volunteers. Markers of endothelial cell injury (thrombomodulin and von Willebrand factor) were significantly higher in HD and CAPD patients compared to the control group. A similar pattern of changes was observed for lipoprotein(a), fibrinogen, tissue factor pathway activity, and factor VII activity. Activity of factor X was significantly enhanced in CAPD compared to HD patients and controls. Euglobulin clot lysis time was significantly prolonged in HD and CAPD patients over controls, being more prolonged in CAPD patients. Markers of ongoing coagulation (thrombin–antithrombin complexes and prothrombin fragments 1+2) were higher in uremic patients, significantly higher in CAPD than in HD. A marker of ongoing fibrinolysis (plasmin–antiplasmin complexes) was higher in uremic patients but was lower in CAPD than in HD patients. Concentrations of TNFα and IL-1 were higher in HD than in CAPD patients.

Conclusion

Patients on CAPD showed evidence of a higher degree of hypercoagulation than HD patients. Thus, hemostatic abnormalities in end-stage renal failure may be affected to some extent by the choice of renal replacement therapy.

A Comprehensive Study on Hemostasis in CAPD Patients Treated with Erythropoietin

Objective

Bleeding diathesis and simultaneous thrombotic complications may be seen in dialyzed patients. Erythropoietin (EPO) may shift the precarious balance of the hemostatic system toward thrombosis. Platelets and tissue factor (TF) play a major role in plug formation. Tissue factor pathway inhibitor (TFPI) appears to play a primary role in regulating TF-induced coagulation. Thrombin activatable fibrinolysis inhibitor (TAFI) is a key protein linking coagulation and fibrinolysis. The aim of the study was to assess whether 6 months of EPO therapy affects platelet function, that is, platelet aggregation and P-selectin level; moieties of the extrinsic coagulation pathway: TF, TFPI, and TFPI/Xa complexes, and factors VII and X; markers of ongoing coagulation: thrombin–antithrombin complexes (TAT) and prothrombin fragments 1+2; a marker of ongoing fibrinolysis: plasmin–antiplasmin complexes (PAP); fibrinolytic activity: euglobulin clot lysis time (ECLT); and markers of endothelial cell injury: von Willebrand factor, thrombomodulin, E-selectin, and TAFI, in continuous ambulatory peritoneal dialysis (CAPD) patients.

Patients and Methods

22 patients on CAPD were given EPO 6000 U/week. 12 patients with chronic renal failure and 12 healthy volunteers served as control groups. All parameters were studied before, and after 1, 3, and 6 months of EPO therapy.

Setting

Department of Nephrology and Internal Medicine, Medical Academy of Bialystok, Poland.

Results

Platelet aggregation in whole blood did not change significantly during EPO treatment. A significant rise in arachidonic acid-induced platelet aggregation in platelet-rich plasma was observed after 3 and 6 months, and in collagen-induced platelet aggregation after 6 months of EPO therapy, compared to the baseline values. The TFPI concentration decreased significantly after 6 months of EPO therapy. The activity of factor VII increased transiently after 1 month of EPO therapy, compared to the baseline values. The TAFI concentration and activity in the CAPD group were significantly higher than in the control group. Erythropoietin therapy resulted in a significant decrease in TAFI concentration and activity after 6 months of EPO treatment. The ECLT was shortened significantly as early as after 1 month of EPO therapy. Thrombomodulin, von Willebrand factor concentration and activity, PAP, TAT, TFPI/Xa complexes, prothrombin fragments 1+2, factor X activity, P-selectin, E-selectin, and lipoprotein(a) did not change significantly during EPO treatment.

Conclusion

Erythropoietin treatment has a minimal effect on hemostasis in CAPD patients. A tendency toward a decline in TAFI is of unknown clinical relevance so far, and awaits further research.

Influence of Simvastatin on Aspects of Thrombogenesis in CAPD Patients

← Background

Patients on continuous ambulatory peritoneal dialysis (CAPD) are prone to dyslipidemia and have a high risk of cardiovascular death. Statins show beneficial effects on serum lipids and thrombogenesis in various groups of patients, but prospective studies have so far not been performed on CAPD patients.

← Aim

To determine the effects of 6 month's treatment with simvastatin on platelet function and some hemostatic parameters, markers of endothelial cell injury, in 14 CAPD patients with hypercholesterolemia.

← Methods

Simvastatin was given in a dose of 10 mg at bedtime. Commercially available kits were used for all determinations.

← Results

Cholesterol and low density lipoprotein fell significantly as early as after 1 month of the therapy ( p < 0.001). Platelet aggregation in whole blood and plateletrich plasma was transiently decreased by simvastatin therapy. The fibrinolytic activity index increased significantly after 6 months of simvastatin administration ( p < 0.05), reaching values observed in the control group, whereas euglobulin clot lysis time, which was also significantly shortened after 6 months ( p < 0.05), did not reach values obtained in healthy volunteers. Vascular cell adhesion molecule, thrombomodulin, and protein Z decreased significantly after 3 months of the therapy ( p < 0.05, p < 0.05, and p < 0.01, respectively), whereas intercellular adhesion molecule decreased after 6 months ( p < 0.05). Vascular endothelial growth factor and its receptor, protein Z, total tissue factor pathway inhibitor (TFPI), TFPI/Xa complexes, and thrombin activatable fibrinolysis inhibitor concentration and activity fell significantly after 6 months of treatment with simvastatin (all p < 0.05). Tissue plasminogen activator concentration increased after 1 month ( p < 0.01 after 1 month, p < 0.05 after 3 and 6 months), whereas total homocysteine fell after 6 months of simvastatin therapy ( p < 0.05). Truncated TFPI decreased significantly as early as after 1 month of therapy ( p < 0.05 after 1 month, p < 0.01 after 3 and 6 months).

← Conclusion

Simvastatin is an effective hypolipemic agent in CAPD patients. It favorably affects platelet aggregation and the extrinsic coagulation pathway, improves fibrinolysis, and ameliorates endothelial dysfunction. Simvastatin might reduce the risk of thrombotic complications in CAPD patients.

Fibrinolysis in patients with chemotherapy-induced thrombocytopenia and the effect of platelet transfusion

Essentials Bleeding in chemotherapy induced thrombocytopenia (CIT) might be influenced by hyperfibrinolysis. t-PA-thromboelastography is a fast and reliable assay for hyperfibrinolysis in CIT patients. Clots of CIT patients are more susceptible to t-PA induced lysis compared to healthy individuals. Besides platelets, other factors are likely to influence clot lysis in CIT patients.

BACKGROUND

Bleeding events in chemotherapy-induced thrombocytopenic (CIT) patients with similar platelet counts might be influenced by changes in clot lysis potential.

OBJECTIVES

To investigate, in an observational study, thromboelastographic lysis parameters, alterations in clot strength and susceptibility to clot lysis in CIT patients. To identify factors associated with fibrinolytic profiles, and to evaluate the effects of platelet transfusions.

METHODS

Independent determinants of tissue-type plasminogen activator (t-PA)-ROTEM lysis parameters were identified with multivariable linear regression. Clot formation, strength and lysis parameters were compared with the results of healthy individuals. Characteristics of CIT patients with and without hyperfibrinolytic profiles were compared. t-PA-ROTEM results before, 1 hour after and 24 hours after platelet transfusion were compared.

RESULTS

A total of 72 consecutive CIT patients were included. t-PA-ROTEM lysis parameters correlated with changes in fibrinolytic proteins. Clot formation time was longer, maximum clot firmness was weaker and lysis times were shorter than in healthy individuals. CIT patients had low plasminogen activator inhibitor-1 and thrombin-activatable fibrinolysis inhibitor levels, and 40% showed hyperfibrinolytic profiles. Platelet transfusions resulted in less hyperfibrinolytic profiles in many, but not all CIT patients. Patients without hyperfibrinolytic profiles had higher fibrinogen, factor VIII and α2 -antiplasmin levels.

CONCLUSIONS

t-PA-ROTEM can be used as a fast and reliable assay to detect hyperfibrinolytic profiles in CIT patients. CIT patients have weaker clots, which are more susceptible to clot lysis, than healthy individuals. Besides platelets, other factors are likely to influence clot susceptibility to fibrinolysis in CIT patients. The impact of a hyperfibrinolytic t-PA-ROTEM profile on bleeding remains to be investigated.

Fibrinolysis in trauma patients: wide variability demonstrated by the Lysis Timer

Hyperfibrinolysis contributes to the pathophysiology of trauma-induced coagulopathy. At present, systematic administration of tranexamic acid (TXA) is recommended in all patients in the early phase of trauma. However, there is some debate regarding whether TXA is beneficial in all trauma patients. A rapid and accurate tool to diagnose hyperfibrinolysis may be useful for tailoring TXA treatment. We conducted a proof-of-concept study of consecutive adult trauma patients. A first blood sample was obtained at the time of pre-hospital care (T1). Patients received 1 g of TXA after T1. A second sample was obtained on arrival at the emergency unit (T2). We examined coagulation, fibrin and fibrinogen formation and degradation. Fibrinolysis was assessed by determining tissue plasminogen activator (t-PA) antigen and plasminogen activator inhibitor 1 (PAI-1) activity and global fibrinolysis capacity assay using a device developed by Hyphen BioMed: the Lysis Timer (GFC/LT). The study population consisted of 20 patients (42 ± 21 years, index of severity score 32 ± 21). Both coagulation and fibrinolysis were altered at T1. GFC/LT values exhibited hyperfibrinolysis only in five patients. Principal component analysis carried out at T1 showed two main axes of alteration. The major axis was related to coagulation, altered in all patients, while the second axis was related to fibrinolysis. GFC/LT was mainly influenced by PAI-1 activity while fibrin monomers were related to the severity of trauma. At T2, GFC/LT exhibited the marked effect of TXA on clot lysis time. In conclusion, GFC/LT demonstrated huge variation in the fibrinolytic response to trauma.

Assessment and determinants of whole blood and plasma fibrinolysis in patients with mild bleeding symptoms

Enhanced clot lysis is associated with bleeding, but assessment of lysis capacity remains difficult. The plasma turbidity lysis and whole blood tissue Plasminogen Activator-Rotational Thromboelastometry (tPA-ROTEM) assays estimate fibrinolysis under more physiological conditions than clinically used assays. We hypothesized that these assays could find signs of enhanced lysis capacity in patients who report bleeding symptoms, but are not diagnosed with bleeding disorders. We also aimed to gain insight in determinants of the results of these lysis assays. Data from 240 patients with and 95 patients without self-reported bleeding symptoms were obtained, who were included in a study that primarily aimed to assess prevalence of haemostatic abnormalities in preoperative patients. ROTEM and turbidity assays were performed with rtPA. Blood counts, fibrinolysis and coagulation factor activities were determined. Data were analysed using multivariable linear regression models. Remarkably, patients reporting bleeding symptoms showed signs of significantly impaired lysis capacity in the tPA-ROTEM, but not in the turbidity lysis assay. In these patients, the tPA-ROTEM results depended on FII, FXII, plasminogen, α2-antiplasmin, PAI-1 and TAFI levels. The turbidity lysis results were significantly influenced by fibrinogen, α2-antiplasmin, PAI-1 and TAFI. In conclusion, the tPA-ROTEM and the turbidity lysis assay could not detect enhanced fibrinolytic capacity in patients with bleeding symptoms. This suggests that these symptoms are not caused by enhanced fibrinolytic activity. As both assays were sensitive to important determinants of fibrinolysis they may be able to detect a fibrinolytic imbalance, but this needs to be validated in patients with known hypo- or hyperfibrinolytic disorders.

Preoperative screening for bleeding disorders: A comprehensive laboratory assessment of clinical practice

BACKGROUND

Patients with mild bleeding disorders are at risk of perioperative bleeding, but screening for these disorders remains challenging.

OBJECTIVES

We aimed to assess the prevalence of hemostatic abnormalities in patients with and without reported bleeding symptoms on a preoperative questionnaire, consisting of guideline-proposed questions, and appraised the diagnostic value of several screening modalities for the identification of patients with hemostatic abnormalities.

METHODS

In this observational study, 240 patients with and 95 patients without bleeding symptoms on the preoperative questionnaire were included. Patients with known bleeding disorders, antithrombotic drugs, thrombocytopenia, and anemia were excluded. Preoperatively, all patients underwent elaborate hemostatic testing. Hemostatic abnormalities were defined as coagulation, vWF, or fibrinolysis factor levels below reference range and platelet function defects. Screening modalities included the ISTH Bleeding Assessment Tool (ISTH-BAT), PT, aPTT, TT, Euglobulin Lysis Time (ELT), and Platelet Function Analyser (PFA).

RESULTS

In 21 of 240 (8.8%) patients reporting bleeding symptoms, hemostatic abnormalities were found, including 7 reduced coagulation factor levels, 10 platelet function abnormalities, and 4 reduced vWF levels. In comparison, 10 of 95 (10.5%) patients not reporting bleeding symptoms had abnormalities. The ISTH-BAT could not identify patients with abnormalities, while PT, aPTT, TT, ELT, and PFA had high specificity but low sensitivity to detect abnormalities.

CONCLUSIONS

The prevalence of hemostatic abnormalities in both patients with and without reported bleeding symptoms was 9%-10%. This suggests that the guideline-based questionnaire cannot differentiate between patients with and without abnormalities, while the discriminative power of the screening modalities is also limited.

Spectrophotometric analysis of thrombolytic activity: SATA assay

Introduction: Measurement of thrombolytic activity is crucial for research and development of novel thrombolytics. It is a key factor in the assessment of the effectiveness of conventionally used thrombolytic therapies in the clinic. Previous methods used for the assessment of thrombolytic activity are often associated with some drawbacks such as being costly, time-consuming, complex with low accuracy. Here, we introduce a simple, economic, relatively accurate and fast method of spectrophotometric analysis of thrombolytic activity (SATA) assay, standardized by tissue plasminogen activator (tPA), which can quantitatively measure in vitro thrombolytic activity.

Methods: Blood clots were formed, uniformly, by mixing citrated whole blood with partial thromboplastin time (PTT) reagent, together with calcium chloride. Then, designated concentrations of tPA were added to the samples, and the released red blood cells from each clot were quantified using spectrophotometry (λ_max=405nm) as an indicator of thrombolytic activity. The accuracy of the method was tested by assessment of dose-responsibility against R² value obtained by linear equation and measurement of the limit of detection (LOD) and limit of quantification (LOQ). The SATA assay was validated in comparison with some currently used techniques.

Results: A linear relationship was obtained between different concentrations of tPA versus the spectrophotometric absorbance of the related dilutions of lysed clots, at λ_max=405nm. Calculated R² values were greater than 0.9; with LOD of 0.90 µg/mL of tPA (436.50IU) and LOQ of 2.99 µg/mL of tPA (1450.15IU).

Conclusion: Conclusively, the SATA assay is a very simple quantitative method with repeatable and reproducible results for estimating the potency of an unknown thrombolytic agent, and calculating the activity as delicate as 1 µg/mL of tPA (485 IU/mL of thrombolytic dose).

Fibrinolysis in trauma: a review

Fibrinolytic dysregulation is an important mechanism in traumatic coagulopathy. It is an incompletely understood process that consists of a spectrum ranging from excessive breakdown (hyperfibrinolysis) and the shutdown of fibrinolysis. Both hyperfibrinolysis and shutdown are associated with excess mortality and post-traumatic organ failure. The pathophysiology appears to relate to endothelial injury and hypoperfusion, with several molecular markers identified in playing a role. Although there are no universally accepted diagnostic tests, viscoelastic studies appear to offer the greatest potential for timely identification of patients presenting with fibrinolytic dysregulation. Treatment is multimodal, involving prompt hemorrhage control and resuscitation, with controversy surrounding the use of antifibrinolytic drug therapy. This review presents the current evidence on the pathophysiology, diagnostic challenges, as well as the management of this hemostatic dysfunction.

LEVEL OF EVIDENCE

Level III.

Development and validation of a high throughput whole blood thrombolysis plate assay

The objective of this work was to develop a high throughput assay for testing in vitro the thrombolytic activity using citrated whole blood samples, and to overcome the limitations of currently available techniques. We successfully developed a method that involves forming halo shaped, tissue factor induced, whole blood clots in 96 well plates, and then precisely measuring the thrombolysis process with a spectrophotometer plate reader. We here describe the implementation of this novel method, which we refer to as halo assay, and its validation with plasmin, urokinase and tissue plasminogen activator at different doses. The resulting data is a highly detailed thrombolysis profile, allowing comparison of different fibrinolytic agents. The time point analysis allows kinetic data to be collected and calculated to determine key parameters such as the activation time and the rate of fibrinolysis. We also assessed the capacity of the model to study the effect of clot maturation time on the fibrinolytic rate, an aspect of thrombosis rather unexplored with currently available methods, but of increasing importance in drug development. This novel thrombolysis assay could be an extremely useful research tool; to study the complex process of thrombolysis, and a valuable translational clinical tool; as a screening device to rapidly identify hypo- or hyper-fibrinolysis.

Fibrinolysis status in the Budd-Chiari syndrome in China

Pathogenesis and clinical characteristics of the Budd-Chiari syndrome (BCS) in Asia are somewhat different from the ones observed in Western countries. Obstruction of the inferior vena cava (IVC) or of the hepatic veins is caused to a greater extent by membranous webs than by thrombosis. Impaired fibrinolysis has been found in European patients with BCS, but its status in Chinese patients with this condition is still unknown. To explore the characteristics of fibrinolysis in BCS patients in this country, we measured the euglobulin lysis time (ELT) for overall fibrinolysis and the plasma levels of five fibrinolytic components in 65 Chinese patients with BCS and 43 healthy controls. In patients, ELTs were slightly shorter than in controls (mean, 293 vs. 357 min, P < 0.02), tissue type plasminogen activator levels were higher than in controls (mean, 239 vs. 185 pg/ml, P < 0.01), and plasminogen activator inhibitor 1 levels were lower than in controls (mean, 1.43 vs. 1.73 ng/ml, P < 0.001). To explore BCS in more detail, we subgrouped the cases according to age, type of venous occlusion, Child-Pugh score, and thrombosis. As a result of this analysis, we found that young patients (age <30 years) had a longer ELT (mean, 440 min) than the older patient groups (30 ≤ age ≤ 44, 45 ≤ age ≤ 54, age>54 years; mean ELT = 242, 198, and 289 min, respectively, all P < 0.05). The independent hepatic vein occlusion subgroup showed a longer ELT (mean, 367 min) than the combined hepatic vein and IVC or the independent IVC occlusion subgroup (mean ELT = 233 and 260 min, both P < 0.05). ELT did not show significant differences between Child-Pugh class A and B subgroups (mean, 267 vs. 333 min, P > 0.05). ELT in the subgroup without thrombosis was shorter than in controls (mean, 288 vs. 358 min, P < 0.05), and in the subgroup with thrombosis, it was also slightly shorter than in controls, without reaching statistical significance (mean, 306 vs. 358 min, P > 0.05). By and large, overall fibrinolytic potential was slightly increased in Chinese patients with BCS in this study, but fibrinolysis differed according to its baseline characteristics. Compared with the one seen in BCS patients from Western countries, BCS in China exhibits certain special changes in fibrinolysis and we were able to explain some of these changes.

A new anti-fibrinolytic hemostatic compound 8-O-acetyl shanzhiside methylester extracted from Lamiophlomis rotata

BACKGROUND

Fibrinolysis prevents blood clots from growing and becoming problematic. Antifibrinolytics are used as inhibitors of fibrinolysis. Aprotinin was doubted after identification of major side effects, especially on kidney. Lysine analogues has their own defects and whether they are adequate substitutes for aprotinin is still under doubt. Lamiophlomis rotata (Benth.) Kudo. was previous found to have hemostatic activity. But the active compound in L. rotata and its hemostatic mechanism were unknown.

OBJECTIVES

To find the major hemostatic compound in L. rotata and identify its haemostasis mechanism.

METHODS

Traumatic hemorrhage model and coagulant activity assays were monitored in mice and platelets in drug treatment group and control group. Hyperfibrinolysis model was established by intravenous administration of urokinase in mice. Capillary blood clotting time (CBCT), activated partial thromboplastin time (APTT), prothrombin time (PT), thrombin time (TT), fibrinogen and euglobulin clot lysis time (ECLT) were measured.

RESULTS

The anti-fibrinolytic activity come from 8-O-Acetyl shanzhiside methylester (ASM) one of the highest iridoid glycosides contents in TIG extracted from L. rotata. ASM significantly (P<0.05) shorten CBCT and reduced blood loss volume in vivo, but did not influence mice APTT, PT or TT. In particular, it significantly prolonged ECLT in hyperfibrinolysis mice. It indicated that ASM could inhibit fibrinolysis. ASM was also effective in CBCT, traumatic bleeding volume and ECLT in hyperfibrinolysis mice model.

CONCLUSIONS

ASM was the major hemostatic compound in L. rotata. The haemostasis mechanism of ASM was achieved by anti-fibrinolytic activity. ASM was a new fibrinolysis inhibitor as iridoid glycoside compound.

Validation of a modified thromboelastometry approach to detect changes in fibrinolytic activity

Background

Thus far, validated whole blood assays used in in vitro fibrinolysis experiments using thromboelastometry (ROTEM) are lacking or have yet to be tested in humans.

The objective was first, to establish a standardized modified ROTEM approach to detect both hypo- and hyperfibrinolysis. And second, to perform a technical and clinical validation of the assay.

Methods

Blood was used of healthy volunteers, patients with sepsis, patients after cardiothoracic surgery, pregnant women, and cirrhotic liver disease patients. A whole blood tissue factor (TF) activated ROTEM assay with and without the addition of recombinant tissue plasminogen activator (rTPA) was developed. Plasma fibrinolysis determinants were measured in all volunteers and patients.

Results

Thirty five pM TF and additions of 125 and 175 ng/ml rTPA resulted in full lysis within 60 min in healthy volunteers. Coefficients of variation were below 10 % without and below 20 % with rTPA addition. In sepsis the hypofibrinolytic ROTEM profiles with 175 ng/ml rTPA were in line with the plasma determinants (high PAI-1, high fibrinogen, low tPA activity, and high d-dimers). After cardiothoracic surgery, reduced fibrinogen and platelet levels accounted for the reduced maximum clot firmness. The hypofibrinolytic profile is attributed to tranexamic acid use and elevated PAI-1 levels. The lowest rTPA concentration in cirrhosis resulted in hyperfibrinolysis in only few of the patients. In pregnancy normal profiles were found.

Discussion

Our high rTPA concentration demonstrates hypofibrinolytic profiles adequately in sepsis and after cardiothoracic surgery. Our low rTPA concentration of 125 ng/ml seems too high for demonstrating hyperfibrinolysis in cirrhotic liver disease.

Conclusions

We were able to present a validated whole blood ROTEM approach to fibrinolysis testing using added rTPA, which can be of added value next to classical plasma based fibrinolysis assays.

Endogenous Fibrinolysis: An Important Mediator of Thrombus Formation and Cardiovascular Risk

Most acute cardiovascular events are attributable to arterial thrombosis. Plaque rupture or erosion stimulates platelet activation, aggregation, and thrombosis, whilst simultaneously activating enzymatic processes that mediate endogenous fibrinolysis to physiologically maintain vessel patency. Interplay between these pathways determines clinical outcome. If proaggregatory factors predominate, the thrombus may propagate, leading to vessel occlusion. However, if balanced by a healthy fibrinolytic system, thrombosis may not occur or cause lasting occlusion. Despite abundant evidence for the fibrinolytic system regulating thrombosis, it has been overlooked compared with platelet reactivity, partly due to a lack of techniques to measure it. We evaluate evidence for endogenous fibrinolysis in arterial thrombosis and review techniques to assess it, including biomarkers and global assays, such as thromboelastography and the Global Thrombosis Test. Global assays, simultaneously assessing proaggregatory and fibrinolytic pathways, could play a role in risk stratification and in identifying impaired fibrinolysis as a potential target for pharmacological modulation.

Effects of a novel marine natural product: pyrano indolone alkaloid fibrinolytic compound on thrombolysis and hemorrhagic activities in vitro and in vivo

Fungi fibrinolytic compound 1 (FGFC1) is a novel marine natural product as a low-weight fibrinolytic pyranoindole molecule, whose thrombolytic effects were evaluated on FITC-fibrin (Fluorescein isothiocyanate, FITC) degradation methods in vitro and on acute pulmonary thromboembolism animal model in vivo. We determined the FGFC1 induced thrombolysis that stems from its fibrin(ogen)olytic activities as measured by fibrin(ogen) degradation products (FDPs) experiment, acute pulmonary thromboembolism animal model experiment, and euglobulin lysis assay. In vitro, measurement of FITC-fibrin degradation revealed that fibrin hydrolysis occurred in a concentration-dependent manner of FGFC1 from 5 to 25 μ mol/L. In vivo test of a classical acute pulmonary thromboembolism model in rat showed that when the injected dose was 5 mg/kg or above, FGFC1 was effective in dissolution of extrinsic FITC-fibrin induced blood clots. Euglobulin lysis time (ELT) in FGFC1-treated rats was shortened 30 s compared with rats in the positive control group, which were injected with clopidogrel sulfate and single-chain urokinase-type plasminogen activator. As compared to the control, FGFC1 (5-25 mg/kg) did not significantly alter the formation of fibrinogen and FDPs in vivo. Our research indicates that FGFC1 presents pharmacodynamic action in both the thrombolysis and the hemolytic procedure, which can be characterized by fibrinogenolysis in blood and FDPs in plasma. In vivo, increasing fibrinolytic doses of FGFC1 from 5 to 25 mg/kg did not induce fibrinogenolysis when compared with control group, this result corresponds to that FGFC1 did not induce the increasing of FDPs (compared with the saline-treated control). It indicates that the FGFC1 may act as a novel thrombolytic agent and represent an effective approach to the treatment of thrombus without significant risk of hemorrhagic activity.

Global haemostasis assays, from bench to bedside

Bleeding and thrombosis are the ultimate clinical outcomes of aberrations in the haemostatic process. Haemostasis prevents excessive blood loss due to the effort of various compartments like the vasculature, blood cells, coagulation and fibrinolysis. The complexity of all processes involved makes the diagnosis of aberrations difficult, cumbersome and expensive. A single assay to detect any factor disturbing this haemostatic balance with high sensitivity and specificity would be of great value, especially if the outcome of this assay correlates well with clinical outcome. Despite years of research, such an assay is not yet available; however, some interesting candidates are under development and combine the effects of various compartments. This review describes the development of global haemostasis assays and summarizes the current state of the art of these haemostasis assays covering thrombin and plasmin generation, turbidity and thromboelastography/thromboelastometry. Finally, we discuss the applicability of global assays in clinical practice and we provide a future perspective on the ongoing development of automation and miniaturisation as it is our belief that these developments will benefit the standardization of global haemostasis assays.

Effects of enoxaparin preparations on thrombin generation and their correlation with their anti-FXa activity

OBJECTIVE

Anticoagulant effect of LMWHs is monitored by anti-factor Xa (anti-FXa) activity assay. Since this test has several limitations, the aim of this study was to explore the activity of two LMWHs by thrombin generation assay (TG, which presents an overall picture of hemostatic balance) and its correlation with their anti-FXa activity.

METHODS

In an open-label, randomized cross-over study, 40  mg of two enoxaparins, the original branded formulation (R) and another one, also marketed in Argentina (T), were daily injected subcutaneously, for 7 days, to 20 healthy volunteers, with a 7-day washout interval. Blood samples were collected before treatment and 180  minutes after the injection on days 3 and 7. TG in platelet-poor plasma activated with tissue factor was assessed by lag time (LT), time to peak (TTP), peak (PTG), and endogenous thrombin potential (ETP). Anti-FXa and anti-FIIa activities, free tissue factor pathway inhibitor (free TFPI), tissue plasminogen activator (t-PA), plasminogen activator inhibitor type 1 (PAI-1), and euglobulin lysis time (ELT) were also assayed.

RESULTS

The mean (SD) anti-FXa (UI/ml) for T and R increased on days 3 and 7. LT and TTP were significantly prolonged by both LMWHs, with no differences between them. The mean ETP (nmol/L) for T and R at 3 and 7 days after treatment were significantly reduced when compared with basal values (p = 0.001 for all). On day 3, a significant correlation was shown between the variables describing TG and anti-FXa for T and R, without differences between them, for LT (r: 0.516 and 0486), ETP (r: 0.532 and 0.574), PEAK (r: 0.482 and 0.501), and TTP (r: 0.577 and 0.503), respectively. This correlation was also significant on day 7. Anti-FIIa activity and free TFPI increased significantly at 3 and 7 days for both LMWHs, without differences between them. R and T decreased ELT and PAI-1, but had no effect on t-PA. There were no differences between both LMWHs in routine hemostatic tests. No adverse events were reported.

CONCLUSIONS

Correlation between TG and anti-FXa activity was good. Both enoxaparins induced similar change of coagulation parameters, with a significant increase in fibrinolytic activity.

Development of a new test for the global fibrinolytic capacity in whole blood

BACKGROUND

The development of global tests for the fibrinolytic capacity in blood is hampered by the low base-line fibrinolytic activity in blood, by the involvement of both plasmatic components and blood cells in the fibrinolytic system and by the loss of fibrinolytic activity as a result of the action of plasminogen activator inhibitor-1 (PAI-1).

OBJECTIVE

To develop a new test for the global fibrinolytic capacity (GFC) of whole blood samples.

METHODS AND RESULTS

Collection of blood in thrombin increased the subsequent generation of fibrin degradation products. This was ascribed to rapid clot formation and concomitant reduction of in vitro neutralization of tissue-type plasminogen activator (tPA) by PAI-1. On the basis of this observation, the following test was designed: blood samples were collected in thrombin with and without aprotinin and clots were incubated for 3 h at 37 degrees C. The GFC was assessed from the difference between the fibrin degradation products in the two sera. The assay was applied to blood samples from patients and healthy subjects. Other hemostasis parameters were determined in plasma samples taken simultaneously. The GFC varied considerably (normal range 0.13-13.6 microg mL(-1)); physical exercise strongly increased the GFC. Statistically significant correlations were found with tPA activity, PAI-1 activity and fibrinogen level. A mixture of antibodies against tPA and urokinase-type plasminogen activator (uPA) completely inhibited the GFC. An inhibitor of activated thrombin-activatable fibrinolysis inhibitor (TAFI) accelerated fibrinolysis 8-fold.

CONCLUSION

The new test represents a global assessment of the main fibrinolytic factors in plasma and potentially those associated with blood cells.

[Effects of fraction from Phyllanthus urinaria on thrombosis and coagulation system in animals]

OBJECTIVE

To investigate the effects of PUW (a fraction containing 60% corilagin from a Chinese herbal plant Phyllanthus urinaria) on thrombosis and coagulation system.

METHODS

Myers's method was used to evaluate the protection of intravenously administered PUW against the male mouse sudden death caused by injection of 75 mg/kg arachidonic acid in the tail vein; Charlton's method was modified to observe antithrombotic effect of PUW in rat electrically stimulated carotid artery thrombosis model; and the model of venous thrombosis was produced to investigate the antithrombotic effect of PUW. Rosette assay was used to observe the effect of PUW on platelet-neutrophil adhesion. The effects of PUW were monitored on euglobulin lysis time (ELT), prothrombin time (PT), kaolin partial thromboplastin time (KPTT), and bleeding time (BT) in rats, according to the methods of Kowalski, HUANG Zheng-Liang, and GU Yue-Fang, et al, respectively.

RESULTS

The results showed that PUW administered intravenously significantly decreased the mouse mortality, prolonged the occlusion time of rat carotid arteries, and reduced the wet and dry thrombus weight of the inferior vena cava, respectively. PUW markedly inhibited the binding of activated platelets to neutrophils, obtaining 39.7 mg/L of the medium inhibitory concentration. Intravenously administered PUW significantly shortened ELT, prolonged KPTT while had no influence on PT; PUW increased BT in rat tail tips but the BT caused by PUW was much shorter than that by aspirin or urokinase.

CONCLUSION

It is suggested that PUW has the potential of antithrombosis due to its inhibition of platelet-neutrophil adhesion. PUW shows the tendency to bleeding, however, it could not cause serious bleeding side effect as compared with aspirin or urokinase.

Comparative fibrinolytic activity of front-loaded alteplase and the single-bolus mutants tenecteplase and lanoteplase during treatment of acute myocardial infarction

BACKGROUND

Quantification of fibrinolytic activity (FAct) in clinical practice has been abandoned because of the complexity of existing assays. The relationship between thrombolytic drug concentration and FAct is complex. FAct profiles of currently used thrombolytic drugs were not characterized.

METHODS

By use of a system that quantifies FAct by shortening of clot lysis onset time (LOT), we measured LOT in vitro with incremented concentrations of alteplase (t-PA) and tenecteplase (TNK-tPA) and ex vivo in patients with acute myocardial infarction who were receiving front-loaded t-PA (n = 31), 30 to 40 mg TNK-tPA (n = 19), and 120 kU/kg lanoteplase ([n-PA] n = 23).

RESULTS

In vitro, FAct depended on drug concentration by means of a double exponential model revealing 2 distinct activity zones (weak/strong). Ex vivo, no FAct was detected before agent administration (LOT > 1200 seconds). Ten minutes after a bolus was given, FAct was sharply increased in all patients, but it increased more with TNK-tPA than with t-PA or n-PA (mean LOT of 109, 125, and 130 seconds, respectively, P <.05). At 90 minutes, accelerated infusion of t-PA resulted in FAct that remained stronger than that observed for TNK-tPA (P <.0001) or n-PA (P =.011). At 180-minutes, significant FAct (LOT <600 seconds) was only observed in patients who received n-PA.

CONCLUSION

This study provides the first direct comparison of FAct between t-PA, TNK-tPA, and n-PA by use of the LOT test, the results of which are reliably related to drug concentration. The ideal FAct profile would combine an immediate strong FAct of relatively short duration, as seen with TNK-tPA, that may contribute to its better efficacy/safety profile in the Assessment of Safety and Efficacy of a New Thrombolytic Agent-2 (ASSENT-2) trial. Prolonged FAct after n-PA may contribute to increased hemorrhagic complications, as seen in the Intravenous n-PA for Treatment of Infarcting Myocardium Early-2 (InTIME-2) trial. Thus, characterizing FAct profiles might provide insights in developing more efficient thrombolytic regimens.

A new euglobulin clot lysis assay for global fibrinolysis

Plasma fibrinolytic activity has been measured by the euglobulin clot lysis time (ELT) since the late 1950s. The euglobulin clot lysis assay (ECLA) method has been modified using a computerized kinetic spectrophotometric microtiter plate reader and measures optical density changes of recalcified euglobulin fraction of plasma samples over time. This method has been applied to normal healthy adults, children, pregnant women and newborn infants, which represent physiologic extremes of the ELT. The ECLA method adds measurements of maximum absorbance (Max Abs), area under the curve (AUC) and mean velocity to the standard clot lysis time. The resulting curves are unique to this method and have been analyzed and compared in order to establish normal ranges. Fibrinogen levels, plasminogen activator inhibitor-1 (PAI-1) antigen, PAI-1 activity and thrombin activatable fibrinolytic inhibitor (TAFI) antigen levels were measured in each individual of the four groups. Each protein measured within each study group except TAFI correlated with the lysis time, maximum absorbance and area under the curve. Considering all four groups together, PAI correlates most highly with lysis time, fibrinogen correlates the highest with Max Abs; fibrinogen and PAI-1 antigen have equally high correlations to AUC. Area under the curve is highly correlated with all coagulation parameters measured; the most significant contributor is fibrinogen. These observations are interesting, but at this time, it cannot be said that any of the test parameters are better than lysis time in distinguishing between these normal physiologic states.

Changes in blood coagulation and fibrinolysis associated with maximal exercise and physical conditioning in women taking low dose oral contraceptives

Blood coagulation parameters (thromboplastin time. PT; activated partial thromboplastin time, aPTT; fibrinogen; antithrombin III, ATIII; von Willebrand factor-concentration, vWF; factor VIII-activity, FVIII) and fibrinolytic parameters (plasminogen; (alpha-antiplasmin; euglobulin-lysis-time, Elt; tissue plasminogenactivator-antigen, tPA-antigen; plasminogenactivator-1-antigen, PAI-1-antigen) were evaluated in 34 women on low-dose oral contraceptives (OC) twice at intervals of 12 weeks each time before and after maximal exercise. During the 12 weeks, 24 women took part in an aerobic conditioning program and 10 women were requested to avoid any kind of sports activity for this period. Blood samples were taken before training and before and after maximal treadmill exercise. This procedure was repeated after the training program. After maximal exercise we found a significant reduction of aPTT and PT (increase in %), a decrease in ATIII, vWF, fibrinogen, plasminogen and alpha2-antiplasmin but an increase in fibrinolytic activity (all p<0.05). Maximal exercise is associated with an increase in blood coagulation and fibrinolysis also in women taking OC. After the physical conditioning program an increase in fibrinolytic activity at rest was noted in the training group. Opposed to that the fibrinolytic activity at rest decreased in the control group after abstinence of sports activity over this period (p<0.05, MANOVA).

Ascites fluid as a possible origin for hyperfibrinolysis in advanced liver disease

OBJECTIVES

Advanced liver disease is associated with both exaggerated fibrinolysis and with ascites. This study was undertaken to determine whether fibrinolytic activity exists in the ascites fluid of patients with liver disease and to see whether such activity is associated with evidence of plasma fibrinolysis.

METHODS

Both the ascites fluid and plasma from 15 patients with cirrhotic ascites (group A) were evaluated for markers of fibrinolysis: fragment D-dimer, plasminogen, fibrinogen, and fibrin split products. In addition, the euglobulin lysis time, a test highly specific for fibrinolysis, was evaluated in the ascites fluid samples. As a control group, the plasma from 15 cirrhotic patients without ascites (group B) was evaluated for markers of fibrinolysis.

RESULTS

In group A, elevated fragment D-dimer and fibrin split products were uniformly found in ascites fluid in concentrations that would be considered pathologically elevated if in plasma. Ascites fluid was also depleted, compared with plasma, of both plasminogen and fibrinogen. These results, along with the short euglobulin lysis time in 83% of the patients, suggest that increased fibrinolytic activity is present in ascites fluid. In 93% of these patients, plasma D-dimer was elevated. The mean plasma plasminogen was also low in these patients. In group B, only 33% of patients had elevated plasma D-dimer.

CONCLUSIONS

Ascites fluid has fibrinolytic activity. Because ascites fluid reenters the systemic circulation via the thoracic duct, via a natural peritoneovenous shunt, ascites fluid warrants serious consideration as a pathological fluid that contributes to the systemic fibrinolytic state found in the majority of our patients with ascites.

Syndromes of disseminated intravascular coagulation in obstetrics, pregnancy, and gynecology. Objective criteria for diagnosis and management

This article presents current understanding of the causes, pathophysiology, clinical, and laboratory diagnosis, and management of fulminant and low-grade DIC, as they apply to obstetric, pregnant, and gynecologic patients. General medical complications leading to DIC, which may often be seen in these patients, are also discussed. Considerable attention has been given to interrelationships within the hemostasis system. Only by clearly understanding these pathophysiologic interrelationships can the obstetrician/gynecologist appreciate the divergent and wide spectrum of often confusing clinical and laboratory findings in patients with DIC. Objective clinical and laboratory criteria for diagnosis of DIC have been outlined to eliminate unnecessary confusion and the need to make empiric decisions regarding the diagnosis. Particularly in the obstetric patient, if a condition is observed that is associated with DIC, or if any suspicion of DIC arises from either clinical or laboratory findings, it is imperative to monitor the patient carefully with clinical and laboratory tools to assess any progression to a catastrophic event. In most instances of DIC in obstetric patients, the disease can be ameliorated easily at early stages. Many therapeutic decisions are straightforward, particularly in obstetric and gynecologic patients. For more serious and complicated cases of DIC in these patients, however, efficacy and choices of therapy will remain unclear until more information is published regarding response rates and survival patterns. Also, therapy must be highly individualized according to the nature of DIC, patient's age, origin of DIC, site and severity of hemorrhage or thrombosis, and hemodynamic and other clinical parameters. Finally, many syndromes that are often categorized as organ-specific disorders and are sometimes identified as independent disease entities, such as AFE syndrome, HELLP syndrome, adult shock lung syndrome, eclampsia, and many others, either share common pathophysiology with DIC or are simply a form of DIC. These entities represent the varied modes of clinical expression of DIC and illustrate the diverse clinical and anatomic manifestations of this syndrome.

Poly(2-hydroxyethyl methacrylate) particles for preoperative endovascular occlusion of extensive angiodysplasias

The application of superselective endovascular occlusion in vascular radiology has broadened the scope of possible radical surgery of giant angiodysplasias by reducing considerably the risk of severe haemorrhage during the surgery. Occlusion was performed on 229 patients using spherical and cylindrical particles of porous poly(2-hydroxyethyl methacrylate). The treatment of a patient suffering from angiodysplasia of the pelvis is described as an example. The first day following endovascular occlusion a hypercoagulation reaction developed, with a decrease of both the level of fibrinolysis and of anticoagulant factors. This was mainly due to a decrease of the level of antithrombin III and activation of the factor XIII indicating a strong tendency of intravascular thrombosis. During the third day, the hypercoagulation reaction increased. However, on the fifteenth day, parameters of the haemostasis system were close to normal values. Only the activity of the factor XIII remained high suggesting the stabilization and the organization of fibrin clot in the embolized blood vessel territory.

Fibrinolytic and antifibrinolytic activity in pregnancy

Fibrinolytic activity and serum antifibrinolysin were estimated in normal pregnant women, during and after labour. The decreased fibrinolytic activity found during labour returned to non-pregnant levels within 24 hours of delivery. During the same period, the serum antifibrinolysin was rapidly diminished. It is suggested that the post-partum increase in fibrinolytic activity to non-pregnant levels is due to alterations in the fibrinolytic system itself, as well as to changes in circulating antifibrinolysin.

THE EFFECT OF CALCIUM OF FIBRINOLYSIS IN VITRO

The influence of calcium on fibrinolysis in vitro has been studied. In the absence of inhibitors, fibrinolytic activity is enhanced by calcium. In whole blood the inhibitory effect of calcium on fibrinolysis can be explained by its effect on the inhibitors present. Anti-activator is dependent on the presence of calcium for its formation, although calcium has no further influence on its action. Antiplasmin activity is enhanced by the presence of calcium.

A STANDARD CLOT METHOD FOR THE ASSAY OF PLASMINOGEN ACTIVATORS, ANTI-ACTIVATORS, AND PLASMIN

Details are given of the selection and standardization of reagents for use in a standard clot method for estimating plasminogen activators, anti-activators, and plasmin.

The coagulo-lytic system and endothelial function in cyclosporine-treated kidney allograft recipients

Since thromboembolic complications in transplanted patients are generally attributed to combined abnormalities in platelets and coagulo-lytic system, some hemostatic parameters tPA (tissue plasmogin activator):Ag and activity, its inhibitor-PAIAg and activity, tPA/PAI, thrombin-antithrombin (TAT) and plasmin-antiplasmin complexes (PAP), urokinase-uPA, euglobulin clot lysis time-ECLT, fibrinogen, plasminogen, protein C activity, D-dimer, prothrombin fragments1+2 (F1+2), fibrin monomers, fibronectin, lipoprotein-a, and von Willebrand factor(vWF), were evaluated using commercially available kits. The studies were performed on kidney transplant recipients treated with CsA, azathioprine and prednisone (n=21), and healthy volunteers (n=21). ECLT was significantly prolonged in kidney transplant recipients together with a rise in F1+2,lipoprotein-a, fibrinogen, fibronectin, and vWF when compared with controls. The TPA level was lower, whereas the PAI level was higher in kidney transplant recipients when compared with controls. In conclusion, CsA-treated kidney transplant recipients show evidence of pronounced impairment in fibrinolysis and endothelial damage in comparison with healthy volunteers.

Hemostasis, platelet function and serotonin in acute and chronic renal failure

A pathogenetic role for fibrin deposition and platelet activation in the kidney is thought to play a role in the pathogenesis of acute renal failure (ARF). Thus, some fibrinolytic parameters and platelet function have been studied in 17 patients with ARF and compared to healthy volunteers and subjects with chronic renal failure (CRF). Since serotonin may participate in pathological processes resulting from platelet/vessel wall interactions, its level in the whole blood and plasma was also assayed. In ARF and CRF platelet aggregatory responses in both whole blood and in platelet rich plasma upon stimulation with various agonists (collagen, arachidonic acid, ADP, ristocetin) were lower than those obtained in healthy volunteers. Increased levels of lipoprotein (a), von Willebrand factor (vWF) and fibronectin were found in ARF relative to controls. Protein C activity was significantly lower in patients with ARF. Euglobulin clot lysis time was prolonged in ARF and CRF, reflecting a decreased overall fibrinolytic activity. Activity of tissue plasminogen activator (tPA) inhibitor (PAI) and PAI:Ag were higher in ARF, whereas tPA:Ag, urokinase, tPA/PAI complexes, thrombin-antithrombin complexes (TAT), plasmin-antiplasmin (PAP) complexes, fibrinogen, and F1+2 did not differ between ARF and controls. In CRF elevated levels of TAT, PAP, fibrinogen and prothrombin fragments F1+2 were found, whereas concentration of fibronectin was lowered when compared to controls. In both groups of renal failure patients increased levels of fibrin monomers and d-dimer were found relative to healthy volunteers. Whole blood serotonin was significantly lower, whereas plasma serotonin was significantly higher in patients with ARF and CRF relative to controls. Serotonin uptake and its release from platelets were markedly diminished in patients with ARF and CRF. Chronic renal failure exhibit a slightly different pattern of coagulopathies that acute renal failure.

Poly (2-hydroxyethyl methacrylate) particles for management of hemorrhage of complicated origin: treatment of hemobilia

Poly (2-hydroxyethyl methacrylate) (PHEMA) particles of cylindrical and spherical shape were developed as a preparation for tumor treatment or control of hemorrhage by blocking their blood supply. In this report, PHEMA particles were used for the management of hemobilia, that is, bleeding into biliary passages. The origin of hemobilia in 31 patients was localized by selective angiography. With the objective of prophylaxy of hemorrhage, selective embolization with PHEMA particles of the branches of the hepatic artery responsible for the supply of blood to the focus of damage was used in 18 patients. This low-trauma method allowed either a complete control of bleeding or, at least, intraoperative blood loss was reduced more than twice. Histological investigation of the occluded blood vessels showed that the thrombus was attached to the particles and was reinforced by the porous structure of the polymer. A hypercoagulation reaction was observed in the postembolization period. This allowed correction of the hypocoagulation in the hemostasis system.

Influence of hysterectomy on the fibrinolytic activity of plasma of women with intact ovarian function

Hysterectomies are frequently required operations in gynecology. Several studies have reported an association between premenopausal hysterectomy and the risk of cardiovascular diseases. However, the pathophysiological linkages between these two conditions have not been elucidated. In recent years it has been shown that a decrease in plasma fibrinolytic activity is associated with increased risk of thrombosis. Furthermore, it has been known that the uterus is a very finbrinolytic active organ. In the present study we investigated the hypothesis that hysterectomy may lead to a decrease in plasma fibrinolytic activity, and thereby increase the risk for thromboembolic diseases. Fibrinolytic parameters of plasma were investigated in 26 women before and 6 weeks after premenopausal hysterectomy. Euglobulin lysis time (ELT), a global measure of plasma fibrinolytic activity, and the levels of tissue plasminogen activator (tPA) and plasminogen activator inhibitor type 1 (PAI-1) were not different before and after hysterectomy. The ELT difference before and after venous occlusion, which is a good indicator for the risk of thrombosis, was also not significantly changed after hysterectomy. Estradiol-17 beta, progesterone, LH, FSH and sex hormone binding globulin displayed no significant changes after hysterectomy. Furthermore, the hormone measurements also indicated that the women were premenopausal. There were no correlations between the hormone values and fibrinolytic parameters. These data indicate that premenopausal hysterectomy does not lead to changes in plasma fibrinolytic activity.