Dysfibrinogenemia associated with liver disease

The Yin and the Yang of Hemostasis in End-Stage Liver Disease

Patients with end-stage liver disease (ESLD) undergoing liver transplantation (LT) are prone to thromboses both while on the waiting list and in the perioperative period. This hypercoagulability is associated with significant endothelial dysfunction (ED) due to nitric oxide dysregulation. ED and increased thrombin generation are the main factors responsible for this hypercoagulability. Sepsis alone can significantly alter a patient's coagulation profile. In combination with ESLD, however, sepsis or septic shock are responsible for very complex changes. This makes both the assessment and management of coagulation in septic patients with ESLD very challenging. Viscoelastic testing (VET) is the preferred method of coagulation management in patients with cirrhosis because, as with standard laboratory testing, VET can assess the entire coagulation system including the interaction between both pro- and anticoagulants and platelets.

Viscoelastometry to Manage Bleeding in Liver Disease

A state of "re-balanced haemostasis" describes complex coagulation changes that arise in patients with liver disease. Changes include alterations in procoagulant and anticoagulant proteins, platelets and von Willebrand factor, as well as the fibrinolytic system. Various circumstances including infection, trauma, or surgery may disrupt this balance and predispose an individual to bleeding or thrombosis. The prothrombin time, international normalised ratio, and activated partial thromboplastin time are conventional coagulation screening tests that are routinely employed by clinicians to investigate unexplained bleeding, monitor anticoagulation, and inform preoperative assessments of bleeding risk. These standard coagulation tests assess quantitative defects in procoagulant clotting factors and are insensitive to levels of natural anticoagulants, which together with procoagulant factors, are often perturbed in liver disease. Therefore, the prolongation of clotting times measured by these tests often does not reflect the multifaceted alterations of haemostasis in these patients. Viscoelastic testing (VET) provides a more encompassing assessment of clotting function by recording real-time viscoelastic changes in whole blood and includes parameters that provide information on coagulation factor function, platelet contribution to clot formation, as well as fibrinolysis. To date, VET has been employed to predict and inform transfusion support in obstetric, trauma, and cardiac surgical fields, and its use in patients undergoing liver transplantation is well established. The ability of VET to accurately predict bleeding risk and precisely guide transfusion algorithms for patients with liver disease undergoing other invasive procedures or experiencing bleeding complications has been the topic of research over the last decade. This review is a critical summary of this data and provides a detailed snapshot of the position of VET as a clinical tool in patients with liver disease.

Fibrin clot properties and thrombus composition in cirrhosis

Patients with cirrhosis frequently acquire profound hemostatic alterations, which may affect thrombus quality and composition-factors that determine the susceptibility to embolization and fibrinolysis. In this narrative review, we describe in vitro studies on fibrin clot formation and quantitative and qualitative changes in fibrinogen in patients with cirrhosis, and describe recent findings on the composition of portal vein thrombi in patients with cirrhosis. Patients with mild cirrhosis have increased thrombin generation capacity and plasma fibrinogen levels, which may be balanced by delayed fibrin polymerization and decreased factor XIII levels. With progressing illness, plasma fibrinogen levels decrease, but thrombin generation capacity remains elevated. Fibrinogen is susceptible to posttranslational protein modifications and is, for example, hypersialylated and carbonylated in patients with cirrhosis. Despite changes in thrombin generation, factor XIII levels and the fibrinogen molecule, fibrin fiber thickness, and density are normal in patients with cirrhosis. Paradoxically, fibrin clot permeability in patients with cirrhosis is decreased, possibly because of posttranslational protein modifications. Most patients have normal fibrinolytic potential. We have recently demonstrated that portal vein thrombosis is likely a misnomer as the material that may obstruct the cirrhotic portal vein frequently consists of a thickened portal vein wall, rather than a true thrombus. Patients with cirrhosis often have thrombocytopenia and anemia, which may also affect clot stability and composition, but the role of cellular components in clot quality in cirrhosis has not been extensively studied. Finally, we summarize abstracts on fibrin formation and clot quality that were presented at the ISTH 2022 meeting in London.

Coagulopathies in Intensive Care Medicine: Balancing Act between Thrombosis and Bleeding

Patient Blood Management advocates an individualized treatment approach, tailored to each patient's needs, in order to reduce unnecessary exposure to allogeneic blood products. The optimization of hemostasis and minimization of blood loss is of high importance when it comes to critical care patients, as coagulopathies are a common phenomenon among them and may significantly impact morbidity and mortality. Treating coagulopathies is complex as thrombotic and hemorrhagic conditions may coexist and the medications at hand to modulate hemostasis can be powerful. The cornerstones of coagulation management are an appropriate patient evaluation, including the individual risk of bleeding weighed against the risk of thrombosis, a proper diagnostic work-up of the coagulopathy's etiology, treatment with targeted therapies, and transfusion of blood product components when clinically indicated in a goal-directed manner. In this article, we will outline various reasons for coagulopathy in critical care patients to highlight the aspects that need special consideration. The treatment options outlined in this article include anticoagulation, anticoagulant reversal, clotting factor concentrates, antifibrinolytic agents, desmopressin, fresh frozen plasma, and platelets. This article outlines concepts with the aim of the minimization of complications associated with coagulopathies in critically ill patients. Hereditary coagulopathies will be omitted in this review.

Invasive Procedures in Patients with Cirrhosis: A Clinical Approach Based on Current Evidence

The aim on of this article is to provide an update on the coagulation disturbances of patients with cirrhosis. It summarizes basic concepts of coagulation in cirrhosis, available tests used to predict bleeding, procedures and risk of bleeding, and the rationale and expert-based recommendations of prophylactic measures for patients with cirrhosis who undergo invasive procedures.

The role of cryoprecipitate in human and canine transfusion medicine

OBJECTIVE

To evaluate the current role of cryoprecipitate in human and canine transfusion medicine.

DATA SOURCES

Human and veterinary scientific reviews and original studies found using PubMed and CAB Abstract search engines were reviewed.

HUMAN DATA SYNTHESIS

In the human critical care setting, cryoprecipitate is predominantly used for fibrinogen replenishment in bleeding patients with acute traumatic coagulopathy. Other coagulopathic patient cohorts for whom cryoprecipitate is recommended include those undergoing cardiovascular or obstetric procedures or patients bleeding from advanced liver disease. Preferential selection of cryoprecipitate versus fibrinogen concentrate (when available) is currently being investigated. Also a matter of ongoing debate is whether to administer this product as part of a fixed-dose massive hemorrhage protocol or to incorporate it into a goal-directed transfusion algorithm applied to the individual bleeding patient.

VETERINARY DATA SYNTHESIS

Although there are sporadic reports of the use of cryoprecipitate in dogs with heritable coagulopathies, there are few to no data pertaining to its use in acquired hypofibrinogenemic states. Low fibrinogen in dogs (as in people) has been documented with acute traumatic coagulopathy, advanced liver disease, and disseminated intravascular coagulation. Bleeding secondary to these hypocoagulable states may be amenable to cryoprecipitate therapy. Indications for preferential selection of cryoprecipitate (versus fresh frozen plasma) remain to be determined.

CONCLUSIONS

In the United States, cryoprecipitate remains the standard of care for fibrinogen replenishment in the bleeding human trauma patient. Its preferential selection for this purpose is the subject of several ongoing human clinical trials. Timely incorporation of cryoprecipitate into the transfusion protocol of the individual bleeding patient with hypofibrinogenemia may conserve blood products, mitigate adverse transfusion-related events, and improve patient outcomes. Cryoprecipitate is readily available, effective, and safe for use in dogs. The role of this blood product in clinical canine patients with acquired coagulopathy remains unknown.

Altered clot formation and lysis are associated with increased fibrinolytic activity in ascites in patients with advanced cirrhosis

Analysis of coagulation disorders and assessment of rebalanced hemostasis with the use of traditional coagulation assays is challenging in cirrhotic patients. Therefore, alternative tests are under investigation for the evaluation of coagulopathy in this specific setting. Aim of this study was to analyze the modifications of clot structure and function in cirrhotic patients with different degrees of severity. Cirrhotic patients referred to our Unit were consecutively enrolled. Global test measurements, including clot and lysis assays, clot lysis time, and determination of other fibrinolytic parameters, were performed. Analyses of clot formation, morphology, and lysis were performed with a turbidimetric clotting and lysis assay (EuroCLOT). Lysis of a tissue factor-induced clot by exogenous tissue plasminogen activator was analyzed by studying the modifications of turbidity during clot formation and the following lysis. We evaluated coagulative and fibrinolytic parameters in both plasma and ascites. Urokinase plasminogen activator (uPA) and gelatinase activity in ascites were also measured. We analyzed data from 33 cirrhotic patients (11 in Child-Pugh class A; 22 in class B or C and with ascites) and 21 healthy subjects (HS). In class B/C patients prolonged latency time, a decline in clotting absorbance, and decreased fibrin formation were observed in comparison with class A and HS. Generated curves and Thrombin-Activatable Fibrinolysis Inhibitor (TAFI) progressively declined from HS to class C patients, whereas levels of plasminogen activator inhibitor-1 and tissue plasminogen activator increased. D-dimer levels were markedly increased in ascites, together with significantly smaller levels of TAFI, αlfa2-antiplasmin, and plasminogen. Caseinolytic activity was also present. Class C patients showed smaller amount of uPA and significantly lower levels of matrix metallopeptidases (MMP)2 in ascites in comparison with Class B subjects. Clot formation and lysis are altered in cirrhosis and fibrinolysis is activated in ascites. Ascitic levels of uPA and MMP2 are reduced and inversely related to the severity of liver disease.

Thromboelastography Better Reflects Hemostatic Abnormalities in Cirrhotics Compared With the International Normalized Ratio

GOAL

The goal of this study was to describe potential key differences in thromboelastography (TEG) variables in hospitalized cirrhotics compared with a healthy population, identify patterns of hematologic disturbance with disease progression, and assess the value of traditional tests such as international normalized ratio (INR) and platelet count to determine coagulopathy in cirrhotics.

BACKGROUND

TEG, a functional assay of coagulation, has emerged as a useful tool for predicting bleeding risk in cirrhosis.

STUDY

Hospitalized cirrhotics who received a TEG before any blood products between January 2017 and February 2018 at a liver transplant center were included. Reaction time (r-time), coagulation time (k-time), angle-rate of clot polymerization (α) and maximum clot strength (maximum amplitude) were measured with kaolin-activated citrated blood TEG assays.

RESULTS

A total of 106 cirrhotic patients (Child-Turcotte-Pugh A, B, C; n=25, 25, 56) were identified for comparison against data from 53 healthy controls. TEG parameters in cirrhotics were statistically different from controls. Mean INR and platelet count for all cirrhotics were largely outside the normal reference range, contrary to TEG parameters which demonstrated parameters mostly within the normal reference ranges. The r-time, k-time, and α values in the cirrhotics progressively increased and maximum amplitude values progressively decreased as the liver disease progressed. Regression analysis showed no significant correlations between INR and r-time across any Child-Turcotte-Pugh class (r=0.01, 0.18, 0.23; P=0.95, 0.39, 0.08, respectively).

CONCLUSIONS

Although cirrhotics had TEG parameters within normal ranges, there was a propensity for decreased clot formation as liver function worsened. Importantly, the INR did not correlate with TEG parameters in cirrhotic patients, and given the precarious hemostatic balance in these patients, a TEG may be a better predictor of bleeding risk.

Transfusion strategies in patients with cirrhosis

Bleeding related to portal hypertension and coagulopathy is a common complication in patients with cirrhosis. Complications and management of bleeding is a significant source of healthcare cost and utilization, as well as morbidity and mortality. Due to the scarcity of evidence surrounding transfusion strategies and hemostatic interventions in patients with cirrhosis, there has been significant debate regarding the best practice. Emerging data suggest that evidence supporting transfusion of packed red blood cells to a hemoglobin threshold of 7-8 g/dL is strong. thrombopoietin (TPO) receptor agonists have shown promise in increasing platelet levels and reducing transfusions preprocedurally, although have not specifically been found to reduce bleeding risk. Data for viscoelastic testing (VET)-guided transfusions appear favorable for reducing blood transfusion requirements prior to minor procedures and during orthotopic liver transplantation. Hemostatic agents such as recombinant factor VIIa, prothrombin complex concentrates, and tranexamic acid have been examined but their role in cirrhotic patients is unclear. Other areas of growing interest include balanced ratio and whole blood transfusion. In the following manuscript, we summarize the most up to date evidence for threshold-guided, VET-guided, balanced-ratio, and whole blood transfusions as well as the use of hemostatic agents in cirrhotic patients to provide practice guidance to clinicians.

The Coagulation Profile of End-Stage Liver Disease and Considerations for Intraoperative Management

The coagulopathy of end-stage liver disease results from a complex derangement in both anticoagulant and procoagulant processes. With even minor insults, cirrhotic patients experience either inappropriate bleeding or clotting, or even both simultaneously. The various phases of liver transplantation along with fluid and blood product administration may contribute to additional disturbances in coagulation. Thus, anesthetic management of patients undergoing liver transplantation to improve hemostasis and avoid inappropriate thrombosis in the perioperative environment can be challenging. To add to this challenge, traditional laboratory tests of coagulation are difficult to interpret in patients with end-stage liver disease. Viscoelastic coagulation tests such as thromboelastography (Haemonetics Corporation, Braintree, MA) and rotational thromboelastometry (TEM International, Munich, Germany) have helped to reduce transfusion of allogeneic blood products, especially fresh frozen plasma, but have also lead to the increased use of fibrinogen-containing products. In general, advancements in surgical techniques and anesthetic management have led to significant reduction in blood transfusion requirements during liver transplantation. Targeted transfusion protocols and pharmacologic prevention of fibrinolysis may further aid in the management of the complex coagulopathy of end-stage liver disease.

Procoagulant therapeutics in liver disease: a critique and clinical rationale

The complex nature of haemostasis in patients with liver disease can result in bleeding and/or thrombosis. These opposing outcomes, which have multiple contributing factors, can pose diagnostic and therapeutic dilemmas for physicians. With the high rate of haemorrhagic complications in patients with cirrhosis, we examine the various procoagulants available for use in this population. In this Review, we describe the clinical and current rationale for using each of the currently available procoagulants-vitamin K, fresh frozen plasma (FFP), cryoprecipitate, platelets, recombinant factor VIIa (rFVIIa), antifibrinolytics, prothrombin concentrate complexes (PCC), desmopressin and red blood cells. By examining the evidence and use of these agents in liver disease, we provide a framework for targeted, goal-directed therapy with procoagulants.

Review article: coagulation disorders in chronic liver disease

BACKGROUND

The liver is the site for synthesis of the vast majority of proteins that play a central role in maintaining hemostasis, by participating in the regulation of coagulation and fibrinolysis.

AIM

To summarize the available data on the impact of coagulation disorders in patients with chronic liver disease.

RESULTS

Hepatocellular damage in patients with severe liver disease can lead to abnormalities in the production and function of coagulation and fibrinolytic factors, disrupting the balance between coagulation and anticoagulation systems.

CONCLUSIONS

Hemostatic abnormalities (eg. impaired synthesis of clotting factors, heightened fibrinolysis, disseminated intravascular coagulation, thrombocytopenia, and platelet dysfunction) can increase the risk of bleeding in cirrhotic patients.

Fractionation of snake venom metalloproteinases by metal ion affinity: a purified cobra metalloproteinase, Nk, from Naja kaouthia binds Ni2+-agarose

Snake venom metalloproteinases represent unique probes for analyzing platelet adhesion receptors regulating hemostasis and thrombosis. Snake venom metalloproteinase-disintegrins consist of a propeptide domain, a catalytic domain containing a metal ion-coordination sequence (HEXXHXXGXXH), a disintegrin domain, and a Cys-rich domain. Here, we investigate whether metal ion-affinity chromatography may be used to fractionate venom metalloproteinases based on the metal ion-coordination motif. First, we showed that a purified cobra metalloproteinase, Nk, from Naja kaouthia bound Ni(2+)-agarose, and was eluted by approximately 10mM imidazole, confirming the validity of the approach. Nk cleaved the platelet von Willebrand factor (VWF) receptor, glycoprotein (GP)Ibalpha, with similar activity to the previously reported cobra metalloproteinase, mocarhagin, as shown by EDTA-inhibitable Nk-dependent proteolysis of a purified GPIbalpha extracellular fragment (glycocalicin), and inhibition of (125)I-VWF binding to GPIbalpha on washed human or canine platelets. Second, crude venom from the viper, Trimeresurus albolabris, was fractionated on Ni(2+)-agarose. Samples of flow-through, wash, and imidazole-eluted (0-30mM gradient) fractions were analyzed by (i) SDS-polyacrylamide gel electrophoresis, (ii) immunoblotting with a rabbit anti-mocarhagin antibody, and (iii) assessing metalloproteinase activity using human fibrinogen as substrate. The combined results support the general concept of using Ni(2+)-agarose to fractionate snake venom metalloproteinases.

Management of bleeding emergencies: when to use recombinant activated Factor VII

Recombinant activated Factor VII (rVIIa) was originally released as a clotting factor, with use limited to a select group of patients who had few other treatment options. Due to the apparent ability of rVIIa to stop bleeding, no matter what the underlying cause, there is great interest in use of rVIIa in a wide range of bleeding patients. This article discusses rVIIa and its uses in a variety of patients, especially liver disease and trauma patients, and makes suggestions for appropriate use. Although most of the reports on rVIIa are anecdotes and case series, there is increasing data for clinical trials to help guide usage.

Coagulation defects in trauma patients: etiology, recognition, and therapy

Trauma patients have many reasons to have defects in coagulation. These can be caused by the trauma or because of pre-existing disorders. Trauma patients who are at risk for coagulation defects should be screened with the basic tests (aPTT, INR/PT, platelet counts, hematocrit, and fibrinogen), with therapy based on the results. Attention also should be paid to any other correctable factors such as hypothermia. Finally, pre-existing disorders can influence the patient's hemostasis greatly and may require specific therapies.

Elevated fibrinogen in an acute phase reaction prolongs the reptilase time but typically not the thrombin time

The effects of elevated fibrinogen on thrombin and reptilase times have not been well documented. High fibrinogen levels are common (38% of specimens submitted to our coagulation laboratory). Among 102 patients in the present study, an endogenously elevated fibrinogen level was significantly associated, as follows, with prolonged reptilase times: 1 (4%) of 28 with normal fibrinogen levels, 6 (20%) of 30 with levels in the 400 to 700 mg/dL (4.0-7.0 g/L) range, 10 (34%) of 29 with levels in the 700 to 1,000 mg/dL (7.0-10.0 g/L) range, and 7 (47%) of 15 with fibrinogen levels greater than 1,000 mg/dL (10.0 g/L). This association was independent of patient age and fibrin degradation product titer. In contrast, thrombin time was not altered notably by elevated fibrinogen levels. In 4 patients studied further, the prolonged clotting times could be corrected or nearly corrected by adding calcium chloride or albumin, whereas no such corrections were demonstrable in samples from several hereditary dysfibrinogenemia control subjects. An elevated fibrinogen level is common and is associated with reptilase time prolongations. For patients with prolonged reptilase times, a fibrinogen assay is suggested before establishing a diagnosis of dysfibrinogenemia.

Laboratory diagnosis of dysfibrinogenemia

Dysfibrinogenemia is a coagulation disorder caused by a variety of structural abnormalities in the fibrinogen molecule that result in abnormal fibrinogen function. It can be inherited or acquired. The inherited form is associated with increased risk of bleeding, thrombosis, or both in the same patient or family. Traditionally, dysfibrinogenemia is diagnosed by abnormal tests of fibrin clot formation; the thrombin time and reptilase time are the screening tests, and the fibrinogen clotting activity-antigen ratio is the confirmatory test. The inherited form is diagnosed by demonstrating similar laboratory test abnormalities in family members, and if necessary by analysis of the fibrinogen protein or fibrinogen genes in the patient. The acquired form is diagnosed by demonstrating abnormal liver function tests and by ruling out dysfibrinogenemia in family members. This article reviews the laboratory testing of dysfibrinogenemia and presents an algorithm for sequential test selection that can be used for diagnosis.

Hematologic management of gastrointestinal bleeding

The hematologic management of gastrointestinal (GI) bleeding requires evaluation of the underlying cause of bleeding, associated diseases that can exacerbate the bleeding, and identification of related and unrelated coagulation abnormalities. Erythrocyte transfusions are given to increase oxygen carrying capacity; however, there is limited information on the level of anemia that places a patient at increased risk of adverse events after a GI bleed and when patients should receive erythrocyte transfusion. Isolated thrombocytopenia is uncommon in patients with GI bleeding, and there is little evidence documenting the degree of thrombocytopenia associated with an increased risk of bleeding. Platelets are often administered when the count is 50,000 per cu/mL in a bleeding patient. The coagulopathy of liver disease is the most common abnormality seen in the setting of GI bleeding. Fresh-frozen plasma (FFP) should be given in a dose equivalent to the underlying abnormality and the common practice of administering 2 units of FFP is often insufficient in a bleeding patient.

Digital ischemia and gangrene due to red blood cell aggregation induced by acquired dysfibrinogenemia

Digital gangrene was observed in a patient who had angiographic findings of digital arterial occlusion. The patient's blood showed a marked red blood cell aggregation with rouleaux formation in long chains, which could not be dispersed at shear rates up to 200 sec-1. Studies of the patient's blood revealed the presence of an abnormal fibrinogen capable of aggregating normal red blood cells. This fibrinogen was found by Raman spectroscopy to have an increased alpha-helical content, whereas the beta-sheet content was decreased. Defibrinogenation therapy with ancrod resulted in a dramatic symptomatic relief. The disappearance of the abnormal fibrinogen 6 months later and an absence of a family history indicate that this dysfibrinogenemia was acquired.

Liver Cirrhosis Manifested by Dysfibrinogenemia

We report a case in which liver cirrhosis was manifested by dysfibrinogenemia before the diagnosis of liver cirrhosis was made. A patient developed gastrointestinal bleeding and hepatic encephalopathy although liver function tests, prothrombin time (PT), activated partial thromboplastin time (aPTT), bleeding time, fibrin (ogen) degradation products (FDP), and platelet counts were normal. However, thrombin time (TT) was prolonged. The gastrointestinal bleeding (GI bleeding) was successfully treated with cryoprecipitate and fresh frozen plasma (FFP). Key Words: Dysfibrinogenemia—Liver disease—Thrombin time.

Inhibition of fibrin monomer polymerisation by myeloma immunoglobulin

Myelomatosis was diagnosed in a 64 year old man on the basis of a serum paraprotein band (type IgG lambda, 42 g/l), plasma cell infiltration of bone marrow, and multiple lytic lesions evident on skull x ray picture. Blood specimens taken into plain glass tubes showed bulky gelatinous clot formation with minimal clot retraction. Coagulation tests were significantly abnormal with an increase in thrombin time, prothrombin time, and reptilase time. The possibility that the paraprotein was interfering with fibrin production was investigated. The rate of fibrin monomer polymerisation (measured turbidometrically) was reduced in patient plasma compared with control plasma. Although purified fibrin monomer prepared from the patient's fibrinogen polymerised normally, the addition of purified paraprotein caused a dose dependent reduction in the rate of polymerisation. These results suggest that the paraprotein was impairing fibrin formation by inhibiting fibrin monomer polymerisation. After chemotherapy the paraprotein concentration decreased and the coagulation results returned to normal.

Disordered hemostasis in extrahepatic portal hypertension

To assess the contribution of naturally occurring portal-systemic shunts to the coagulopathy of patients with liver disease, we studied laboratory parameters of hemostasis in 20 adult patients with extrahepatic portal hypertension, secondary to portal vein thrombosis, that had resulted in variceal bleeding. All extrahepatic portal hypertension patients had normal liver function and histological appearance. None had any evidence of preexisting coagulation disorders, and none had bled or undergone sclerotherapy in the 6 mo before study. Age- and gender-matched groups of 20 healthy individuals and 20 stable patients with cirrhosis and portal hypertension who had a history of variceal bleeding served as controls. Both patient groups had thrombocytopenia consistent with hypersplenism and portal hypertension. Prothrombin international normalized ratio (extrahepatic portal hypertension, 1.3 +/- 0.12; cirrhosis, 1.7 +/- 0.2; control, 1.02 +/- 0.06; p < 0.05) and partial thromboplastin time ratios (extrahepatic portal hypertension, 1.12 +/- 0.1; cirrhosis, 1.26 +/- 0.2; controls, 1.01 +/- 0.03; p < 0.05) were significantly prolonged in both patient groups. Extrahepatic portal hypertension and cirrhotic patient groups had significantly increased levels of serum total fibrin(ogen)-related antigen (extrahepatic portal hypertension, 818 +/- 150 ng/ml; cirrhosis, 454 +/- 52 ng/ml; controls, 124 +/- 7.3 ng/ml; p < 0.05), fibrin monomer (extrahepatic portal hypertension, 168.8 +/- 16.9 ng/ml; cirrhosis, 115.6 +/- 11.1 ng/ml; controls, 19.7 +/- 0.4 ng/ml; p < 0.05) and D-dimer (extrahepatic portal hypertension, 118 +/- 9.6 ng/ml; cirrhosis, 129 +/- 10 ng/ml; controls, 53.2 +/- 1.6 ng/ml; p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Elevated fibrin-related and fibrinogen-related antigens in patients with liver disease

Patients with liver disease have a variety of coagulation abnormalities. These derangements are of uncertain origin and do not always correlate with disease severity or activity. We have measured the levels and proportions of the total fibrin-related and fibrinogen-related antigens, the principal fibrin (D-dimer) and fibrinogen (D-monomer) degradation fragments and intermediates of fibrin formation (fibrin monomers) in patients with a variety of acute and chronic liver diseases in whom all known other precipitating causes of disseminated intravascular coagulation had been excluded. Fibrin-related and fibrinogen-related antigens were extracted from serum using antihuman fibrinogen-IgG covalently bound to activated amino-phenylthioether paper disks and were subjected to 4% to 11% sodium dodecyl sulfate-polyacrylamide gel electrophoresis under nonreducing conditions. Fibrin-related and fibrinogen-related antigen proportions were determined by densitometry, and their levels were measured by radioimmunoassay. Levels of total fibrin-related and fibrinogen-related antigens (and D-dimer) were significantly elevated (p less than 0.01) in patients with cirrhosis (121 to 641 ng/ml) and hepatocellular carcinoma (416 to 8,786 ng/ml) when compared with patients with acute viral hepatitis (84 to 322 ng/ml) and control subjects (38 to 186 ng/ml). In addition, D-monomer levels were elevated. These findings strongly suggest that disseminated intravascular coagulation is a component of the coagulopathy of certain liver diseases. Because fibrin-related and fibrinogen-related antigens have anticoagulant, vasoactive and immunosuppressive properties, their elevated presence may be biologically significant in these patients.

A role for platelets and thrombin in the juvenile stroke of two siblings with defective thrombin-adsorbing capacity of fibrin(ogen)

Binding of iodine-125-labeled thrombin to fibrin clots from two siblings with juvenile stroke was 30% of normal, and abnormally high amounts of the radioligand (not adsorbed by fibrin) were found in the supernatant. In concordance with this finding, supernatants from the patients' fibrin clots caused abnormal enhancement of platelet aggregation, ATP secretion, and binding of 125I-fibrinogen to platelets exposed to subthreshold concentrations of ADP or epinephrine. Hirudin suppressed the enhancing effect of the patients' supernatants, and substitution of gamma-thrombin for alpha-thrombin led to normalization of platelet responses. Under some experimental conditions, degradation of the patients' fibrinogen by plasmin was impaired. However, the euglobulin lysis time, the rate of fibrin degradation by plasmin, and the lysis of the patients' plasma clots by human melanoma tissue-type plasminogen activator were normal. Patients' plasmas, as well as purified fibrinogen, showed a prolonged thrombin time (partially corrected by 10 mM CaCl2) and an impaired release of fibrinopeptide A in response to thrombin. However, the release in response to reptilase was normal, and the reptilase, ancrod, and thrombin coagulase times were within control (normal) values. In addition, the patients' fibrinogen showed normal polymerization of preformed fibrin monomers, normal sialic acid content, and normal binding to ADP or epinephrine-stimulated platelets. Our studies support the concept that thrombin and platelets play an important role in the occurrence of stroke in these patients and suggest a direction to be followed to identify the mechanism(s) contributing to thrombosis in subjects with abnormal fibrinopeptide release.

Endoplasmic storage disease of liver: characterization of intracytoplasmic hyaline inclusions

Two cases of endoplasmic storage disease of liver are described. The liver tissue in each case showed numerous intracytoplasmic hyaline inclusions of varying sizes with formation of ground-glass hepatocytes. These inclusions were pale eosinophilic in hematoxylin & eosin stained sections, and were periodic acid-Schiff and HBsAg negative. Immunoperoxidase studies revealed strong positivity for fibrinogen and complement components C3 and C4 in case 1 and exclusive positivity for fibrinogen in case 2. On electron microscopy, the inclusions appeared as granular or fibrillar material within dilated cisternae of rough endoplasmic reticulum.

Purification of botrocetin from Bothrops jararaca venom. Analysis of the botrocetin-mediated interaction between von Willebrand factor and the human platelet membrane glycoprotein Ib-IX complex

Interaction of von Willebrand factor (vWF) with its platelet receptor only occurs in vitro in the presence of a modulator such as ristocetin. We have recently confirmed that the human platelet membrane glycoprotein (GP) Ib-IX complex is the receptor involved in the ristocetin-dependent binding of vWF by reconstitution with the purified components [Berndt, M.C., Du, X., & Booth, W.J. (1988) Biochemistry 27, 633-640]. We have now developed a similar solid-phase reconstitution assay using an alternate modulator, botrocetin, for the competitive analysis of functional domains in both vWF and the GP Ib-IX complex. Botrocetin was purified from Bothrops jararaca venom by ammonium sulfate fractionation and subsequent DEAE-cellulose and hydroxylapatite chromatography. The purified protein was a 25-kilodalton (kDa) disulfide-linked dimer with apparent subunit molecular weights of 14,000 and 14,500. Binding studies with immobilized botrocetin demonstrated that botrocetin bound to vWF and to a 52/48-kDa region of vWF that contains the GP Ib binding domain, but not to glycocalicin, a proteolytic fragment of GP Ib that contains the vWF binding site. Binding of 125I-labeled vWF to GP Ib-IX complex coated beads and to platelets was strictly botrocetin-dependent with half-maximal binding at a botrocetin concentration of congruent to 0.27 microM. Botrocetin-dependent binding of vWF was specific, saturable, and comparable to that observed with ristocetin. An anti-vWF monoclonal antibody, 3F8, inhibited ristocetin- but not botrocetin-dependent binding of vWF, suggesting the presence of distinct ristocetin and botrocetin modulator sites on vWF. The botrocetin reconstitution assay was at least an order of magnitude more sensitive than the corresponding ristocetin assay for the competitive analysis of functional domains on both vWF and the GP Ib-IX complex and has confirmed the localization of the vWF-binding domain to the 45-kDa N-terminal region of GP Ib.

The mechanism of heparin-induced platelet aggregation

When heparin was added to platelet-rich plasma, mild but irreversible platelet aggregation was demonstrated. This platelet response was not accompanied by release of alpha-granules and dense body constituents, nor by prostaglandin biosynthesis. It did, however, require metabolic energy and divalent cations as metabolic inhibitors (anti-mycin A and 6-deoxyglucose) and EDTA blocked the reaction. Bernard-Soulier syndrome platelets, which lack glycoprotein (GP) Ib, but not Glanzmann's Thrombasthenia platelets, which lack GP IIb/IIIa, were aggregated by heparin. Monoclonal antibody (mAb) against GP IIb/IIIa, but not mAb against GP Ib, strongly inhibited the reaction. These combined results suggest the participation of GP IIb/IIIa but not GP Ib in heparin-induced platelet aggregation. Fibrinogen was a cofactor in the reaction as gel-filtered platelets were unreactive to heparin but addition of fibrinogen restored their reactivity. Antithrombin III and fibronectin inhibited platelet response to heparin, suggesting that these proteins may protect platelets from aggregation by heparin.

Type IIB von Willebrand factor with normal sialic acid content induces platelet aggregation in the absence of ristocetin. Role of platelet activation, fibrinogen, and two distinct membrane receptors

Three preparations of purified von Willebrand factor (vWF), obtained from unrelated patients affected by type IIB von Willebrand disease, were found to have normal sialic acid content (between 129 and 170 nmol/mg of vWF, as compared with 158 +/- 17 nmol/mg in four normal preparations) and to induce platelet aggregation in the presence of physiologic levels of divalent cations and without addition of ristocetin. A monoclonal antibody that blocks the vWF binding domain of the platelet glycoprotein (GP)Ib caused complete inhibition of IIB vWF-induced aggregation. In contrast, a monoclonal antibody that blocks the receptor for adhesive proteins on the platelet GPIIb/IIIa complex failed to inhibit the initial response of platelets to high concentrations of IIB vWF. Moreover, IIB vWF caused agglutination of formalin-fixed platelets that was blocked only by the anti-GPIb antibody, suggesting that the binding of vWF to GPIb, even in the absence of ristocetin, results in platelet-platelet interaction that is followed by exposure of the GPIIb/IIIa receptors for adhesive proteins. Endogenous ADP, normally active platelet metabolism and fibrinogen binding to GPIIb/IIIa were necessary for maximal and irreversible platelet aggregation. In the absence of fibrinogen, however, aggregation was mediated by vWF binding to GPIIb/IIIa. A 52/48-kD tryptic fragment containing the GPIb binding domain of normal vWF completely blocked the aggregation induced by all three IIB vWF preparations. The present study defines in detail the mechanisms involved in IIB vWF-induced platelet aggregation. Moreover, it establishes that the GPIb binding domain of normal and IIB vWF are closely related and that desialylation is not required for the direct interaction of IIB vWF with GPIb.

Study of the formation of fibrin clot in cirrhotic patients. An approach to study of acquired dysfibrinogenemia

Alterations in the coagulation system are common in patients with liver disease. We have examined the importance of the species and chains of fibrinogen in 3 groups of cirrhotic patients. The study of the gelation of fibrinogen in cirrhotic patients shows that the lag time increases in 80.3% of them and that the maximum gelation rate is altered in 51% of these plasmas. Also it is observed that 80% of the plasmas from cirrhotic patients have a percentage (23.3 +/- 7.7%) of unpolymerized alpha chain, after highly cross-linked fibrin formation. These alterations, in lag time and in the maximum gelation rate, have no significant correlation with the situation of the fibrinolytic system in these patients. The study of isolated fibrinogen from cirrhotic patients and normal subjects plasma, shows that there are no objective alterations in the percentage of fibrinogen species, the amount of sialic acid or the ratio of polypeptide chains.

An autoantibody with potent antithrombin activity whose action could be inhibited by toluidine blue or methylene blue

A 41-year-old man with posthepatic liver cirrhosis and bleeding tendency was found to have a circulating anticoagulant with potent antithrombin activity. The thrombin time of the patient's purified fibrinogen was normal. This anticoagulant was residing in the patient's IgG fraction, and his IgG fraction could prolong the thrombin time of purified fibrinogen, suggesting that this circulating anticoagulant was an antibody. No heparin was detected in the patient's plasma. However, the antithrombin activity of this anticoagulant could be neutralized by toluidine blue or methylene blue ex vivo.

Role of sialic acid in acquired dysfibrinogenemia associated with liver cirrhosis

The possible existence of acquired dysfibrinogenemia was investigated in blood samples from 30 patients with liver cirrhosis, 15 newborns and 30 healthy control subjects. Alterations of thrombin time were found in newborns and in 14 cirrhotic patients; glucide fraction levels were measured in these subjects and an increase in sialic acid content was observed. Its functional role was studied by comparing thrombin time and electrophoretic mobility of purified and desialylated forms of fibrinogen. We observed a thrombin time normalization, which was initially prolonged upon the removal of the sialic acid. The anodic electrophoretic mobility underwent changes due to the removal of sialic acid.

Acquired dysfibrinogenemia secondary to mithramycin toxicity

A 58-year-old black woman with IgD multiple myeloma developed a hemorrhagic diathesis within 48 hours after receiving mithramycin (20 micrograms/kg/day) for therapy of hypercalcemia. Her coagulation studies were characterized by prolonged prothrombin, partial thromboplastin, thrombin, and reptilase clotting times. Her plasma and partially purified fibrinogen were inhibitory to the clotting of normal plasma and fibrinogen. The patient's isolated fibrinogen showed a normal rate of fibrinopeptide release, but her fibrin monomer aggregation was markedly abnormal. These studies document the development of a dysfibrinogenemia secondary to mithramycin toxicity.

The spectrum of Epstein-Barr virus hepatitis in children

The clinical and pathologic features of Epstein-Barr virus (EBV) hepatitis in 3 children are described. Manifestations included fever, hepatomegaly, disseminated intravascular coagulation, and failure of uptake of technetium by the reticuloendothelial system of the liver. Histologic features may mimic chronic active hepatitis and lymphoid malignancy. Two patients underwent exploratory laparotomy because of suspected tumor. Recognition of the wide spectrum of hepatic involvement in infectious mononucleosis is important in the differential diagnosis of hepatomegaly. Diagnosis should be made by measurement of IgM-specific EBV antibodies.

Fibrinogen and fibrin: biochemistry and pathophysiology

Fibrinogen is a thrombin-coagulable glycoprotein occurring in the blood of vertebrates. The primary structure of the alpha, beta, and gamma polypeptide chains of human fibrinogen is known from amino acid and nucleic acid sequencing. The intact molecule has a trinodular, dimeric structure and is functionally bivalent. Thrombin cleaves short peptides from the amino termini of the alpha and beta chains exposing polymerization sites that are responsible for the formation of fibrin fibers and appearance of a clot. The major physiological function of fibrinogen is the formation of fibrin that binds together platelets and some plasma proteins in a hemostatic plug. In pathological situations, the network entraps large numbers of erythrocytes and leukocytes forming a thrombus that may occlude a blood vessel. Fibrinogen and fibrin are multifunctional proteins. Fibrinogen is indispensable for platelet aggregation; it also binds to several plasma proteins, however, the biological function of this interaction is not completely understood. Fibrin is an essential matrix for regulation of fibrinolysis and for facilitation of cell attachment in wound healing.

Platelet thrombospondin haemagglutinin activity is due to aggregate formation

Thrombospondin released from human blood platelets by thrombin activation formed high molecular weight aggregates which co-eluted with haemagglutinin activity on Sepharose 4B gel filtration. Thrombospondin aggregation was mediated by intermolecular disulphide bridges. The aggregates consisted of a series of oligomers ranging from a dimer to polymeric forms with Mr congruent to 40 X 10(6). Native monomeric thrombospondin obtained by a modified procedure was deficient in haemagglutination activity but inhibited haemagglutination induced by aggregated thrombospondin.

Acquired dysfibrinogenemia. Paraneoplastic syndrome in renal cell carcinoma

Acquired dysfibrinogenemia has not been previously reported as a paraneoplastic marker for malignancy. This report describes the clinical course of a patient who at the time of diagnosis of nonmetastatic renal cell carcinoma had dysfibrinogenemia characterized by prolongation of the thrombin and Reptilase times and increased sialic acid content of the purified fibrinogen. The thrombin and Reptilase times returned toward normal values after nephrectomy but became abnormal with the development of nonhepatic metastases. It is concluded that acquired dysfibrinogenemia can be part of a paraneoplastic syndrome and is a sensitive plasma marker for tumor progression.

An abnormal fibrinogen (Copenhagen II) with increased sialic acid content associated with thrombotic tendency and normal liver function

An increased sialic acid content of the fibrinogen molecule is found in foetal fibrinogen and as an acquired disorder in hepatic disease. A qualitatively abnormal fibrinogen was detected in the plasma of a 25-year-old man with a thrombotic tendency. The purified fibrinogen had a significantly increased content of sialic acid, an abnormal fibrin monomer polymerization, and a changed mobility in crossed affinity-immunoelectrophoresis using immobilized helix pomatia lectin. The patient had no biochemical or clinical signs of liver disease. The occurrence of a thrombotic tendency and an increased fibrinogen sialic acid content without signs of liver disease may represent a new variant of congenital dysfibrinogenaemia.

Hereditary hypofibrinogenemia with fibrinogen storage in the liver

A family with hereditary autosomal dominant hypofibrinogenemia is described. The outstanding feature is massive deposition of fibrinogen/fibrin within hepatocytes, faintly visible in routine microscopic sections, but clearly demonstrable by immunohistologic techniques. Circulating fibrinogen shows normal electrophoretic mobility of A alpha-, B beta-, and gamma-chains. We assume that the hereditary defect in this family interferes with fibrinogen release from hepatocytes. Clinically there are fluctuating slight elevations of serum transaminase levels. Hemostasis and wound healing are undisturbed.

Morphological and biochemical confirmation of gray platelet syndrome in two siblings

A case report is presented of gray platelet syndrome in siblings. The absence of platelet alpha-granules in these patients was confirmed by electron microscopy and by analysis of the platelet protein profile using SDS-polyacrylamide gel electrophoresis. This was further confirmed by quantitation of individual alpha-granule protein constituents. The results in these two patients are compared with those of the four reported patients with this syndrome.