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Abstract: Results from preclinical sepsis studies using rodents are often criticized as not being reproducible in humans. Using a murine model, we previously reported that visceral adipose tissues (VAT) are highly active during the acute inflammatory response, serving as a major source of inflammatory and coagulant mediators. The purpose of this study was to determine whether these findings are recapitulated in patients with sepsis and to evaluate their clinical significance. VAT and plasma were obtained from patients undergoing intra-abdominal operations with noninflammatory conditions (control), local inflammation, or sepsis. In mesenteric and epiploic VAT, gene expression of pro-inflammatory (TNFα, IL-6, IL-1α, IL-1β) and pro-coagulant (PAI-1, PAI-2, TSP-1, TF) mediators was increased in sepsis compared with control and local inflammation groups. In the omentum, increased expression was limited to IL-1β, PAI-1, and PAI-2, showing a depot-specific regulation. Histological analyses showed little correlation between cellular infiltration and gene expression, indicating a resident source of these mediators. Notably, a strong correlation between PAI-1 expression in VAT and circulating protein levels was observed, both being positively associated with markers of acute kidney injury (AKI). In another cohort of septic patients stratified by incidence of AKI, circulating PAI-1 levels were higher in those with versus without AKI, thus extending these findings beyond intra-abdominal cases. This study is the first to translate upregulation of VAT mediators in sepsis from mouse to human. Collectively, the data suggest that development of AKI in septic patients is associated with high plasma levels of PAI-1, likely derived from resident cells within VAT., Competing Interests: The authors report no conflicts of interest., (Copyright © 2020 by the Shock Society.)

Cardiovascular disease, including stroke, myocardial infarction, and venous thromboembolism, is one of the leading causes of morbidity and mortality worldwide. Excessive coagulation may cause vascular occlusion in arteries and veins eventually leading to thrombotic diseases. Studies in recent years suggest that coagulation factors are involved in these pathological mechanisms. Factors XIa (FXIa), XIIa (FXIIa), and plasma kallikrein (PKa) of the contact system of coagulation appear to contribute to thrombosis while playing a limited role in hemostasis. Contact activation is initiated upon autoactivation of FXII on negatively charged surfaces. FXIIa activates plasma prekallikrein (PK) to PKa, which in turn activates FXII and initiates the kallikrein-kinin pathway. FXI is also activated by FXIIa, leading to activation of FIX and finally to thrombin formation, which in turn activates FXI in an amplification loop. Animal studies have shown that arterial and venous thrombosis can be reduced by the inhibition of FXI(a) or PKa. Furthermore, data from human studies suggest that these enzymes may be valuable targets to reduce thrombosis risk. In this review, we discuss the structure and function of FXI(a) and PK(a), their involvement in the development of venous and arterial thrombosis in animal models and human studies, and current therapeutic strategies., Competing Interests: S.H. is an employee of Bayer AG, Germany. M.V., H.T.C. and H.M.H.S. have nothing to disclose. H.T.C. was a fellow of the Gutenberg Research Foundation and is adjunct professor at the Center for Thrombosis and Hemostasis, Gutenberg University, Mainz, Germany. H.M.H.S. and H.T.C. receive support from the Netherlands Heart Foundation: CVON2014-09, reappraisal of atrial fibrillation: interaction between hypercoagulability, electrical remodeling, and vascular destabilization in the progression of atrial fibrillation (RACE V)., (Georg Thieme Verlag KG Stuttgart · New York.)

The purpose of this review is to describe structure and function of the multiple proteins of the coagulation system and their subcomponent domains. Coagulation is the process by which flowing liquid blood plasma is converted to a soft, viscous gel entrapping the cellular components of blood including red cells and platelets and thereby preventing extravasation of blood. This process is triggered by the minimal proteolysis of plasma fibrinogen. This transforms the latter to sticky fibrin monomers which polymerize into a network. The proteolysis of fibrinogen is a function of the trypsin-like enzyme termed thrombin. Thrombin in turn is activated by a cascade of trypsin-like enzymes that we term coagulation factors. In this review we examine the mechanics of the coagulation cascade with a view to the structure-function relationships of the proteins. We also note that two of the factors have no trypsin like protease domain but are essential cofactors or catalysts for the proteases. This review does not discuss the major role of platelets except to highlight their membrane function with respect to the factors. Coagulation testing is a major part of routine diagnostic clinical pathology. Testing is performed on specimens from individuals either with bleeding or with thrombotic disorders and those on anticoagulant medications. We examine the basic in-vitro laboratory coagulation tests and review the literature comparing the in vitro and in vivo processes. In vitro clinical testing typically utilizes plasma specimens and non-physiological or supraphysiological activators. Because the review focuses on coagulation factor structure, a brief overview of the evolutionary origins of the coagulation system is included., (© 2020 Elsevier Inc. All rights reserved.)

Two complex protein defense systems-complement and coagulation-are based on amplifying enzyme cascades triggered by specific local stimuli. Excess systemic activation of either system is pathologic and is normally prevented by a family of regulatory proteins. The 2 systems are ancient biological processes which share a common origin that predates vertebrate evolution. Recent research has uncovered multiple opportunities for cross talk between complement and coagulation including proteins traditionally viewed as coagulation factors that activate and regulate complement, and proteins traditionally seen as part of the complement system that participate in coagulation. Ten examples of cross talk between the 2 systems are described. The mutual engagement of both systems is increasingly recognized to occur in human diseases. Three conditions-paroxysmal nocturnal hemoglobinuria, atypical hemolytic uremic syndrome, and the antiphospholipid syndrome-provide examples of the importance of interactions between complement and coagulation in human biology. A better understanding of the mutual engagement of these 2 ancient defense systems is expected to result in improved diagnostics and new treatments for systemic diseases., (Copyright © 2019 Elsevier Inc. All rights reserved.)

The role of complement in xenotransplantation is well-known and is a topic that has been reviewed previously. However, our understanding of the immense complexity of its interaction with other constituents of the innate immune response and of the coagulation, adaptive immune, and inflammatory responses to a xenograft is steadily increasing. In addition, the complement system plays a function in metabolism and homeostasis. New reviews at intervals are therefore clearly warranted. The pathways of complement activation, the function of the complement system, and the interaction between complement and coagulation, inflammation, and the adaptive immune system in relation to xenotransplantation are reviewed. Through several different mechanisms, complement activation is a major factor in contributing to xenograft failure. In the organ-source pig, the detrimental influence of the complement system is seen during organ harvest and preservation, for example, in ischemia-reperfusion injury. In the recipient, the effect of complement can be seen through its interaction with the immune, coagulation, and inflammatory responses. Genetic-engineering and other therapeutic methods by which the xenograft can be protected from the effects of complement activation are discussed. The review provides an updated source of reference to this increasingly complex subject., (© 2019 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Chronic myelomonocytic leukemia (CMML) is a myeloid hematological malignancy with overlapping features of myelodysplastic syndromes (MDSs) and myeloproliferative neoplasms (MPNs). The knowledge of the role of the tumor microenvironment (TME), particularly mesenchymal stromal cells (MSCs), in MDS pathogenesis is increasing. Generally, cancer is associated with a procoagulant state participating in tumor development. Monocytes release procoagulant, tissue factor (TF)-bearing microparticles. We hypothesized that MSCs and clonal monocytes release procoagulant extracellular vesicles (EVs) within the CMML TME, inducing a procoagulant state that could modify hematopoietic stem cell (HSC) homeostasis. We isolated and cultured MSCs and monocytes from CMML patients and MSCs from healthy donors (HDs). Their medium EVs and small EVs (sEVs) were collected after iterative ultracentrifugations and characterized by nanoparticle tracking analysis. Their impact on hemostasis was studied with a thrombin generation assay and fibrinography. CMML or HD HSCs were exposed to sEVs from either CMML or HD MSCs. CMML MSC sEVs increased HD HSC procoagulant activity, suggesting a transfer of TF from the CMML TME to HD HSCs. The presence of TF on sEVs was shown by electron microscopy and western blot. Moreover, CMML monocyte EVs conferred a procoagulant activity to HD MSCs, which was reversed by an anti-TF antibody, suggesting the presence of TF on the EVs. Our findings revealed a procoagulant "climate" within the CMML environment related to TF-bearing sEVs secreted by CMML MSCs and monocytes., (© 2019 by The American Society of Hematology.)

A reaction-diffusion system describing blood coagulation in flow is studied. We prove the existence of stationary solutions provided that the speed of the travelling wave problem for the limiting value of the velocity is positive. The implications to the problem of clot growth are discussed.

: Injured blood vessel repair and blood circulation re-establishment are crucial events for tissue repair. We investigated in primary cultures of human umbilical vein endothelial cells (HUVEC), the effects of platelet lysate (PL), a cocktail of factors released by activated platelets following blood vessel disruption and involved in the wound-healing process triggering. PL exerted a protective effect on HUVEC in an inflammatory milieu by inhibiting IL-1α-activated NF-κB pathway and by inducing the secretion of PGE₂, a pro-resolving molecule in the wound microenvironment. Moreover, PL enhanced HUVEC proliferation, without affecting their capability of forming tube-like structures on matrigel, and activated resting quiescent cells to re-enter cell cycle. In agreement with these findings, proliferation-related pathways Akt and ERK 1/2 were activated. The expression of the cell-cycle activator Cyclin D1 was also enhanced, as well as the expression of the High Mobility Group Box-1 (HMGB1), a protein of the alarmin group involved in tissue homeostasis, repair, and remodeling. These in vitro data suggest a possible in vivo contribution of PL to new vessel formation after a wound by activation of cells resident in vessel walls. Our biochemical study provides a rationale for the clinical use of PL in the treatment of wound healing-related pathologies., Competing Interests: The authors declare no conflict of interest

Activation of the intrinsic pathway of coagulation contributes to the pathogenesis of arterial and venous thrombosis. Critical insights into the involvement of intrinsic pathway factors have been derived from the study of gene-specific knockout animals and targeted inhibitors. Importantly, preclinical studies have indicated that targeting components of this pathway, including FXI (factor XI), FXII, and PKK (prekallikrein), reduces thrombosis with no significant effect on protective hemostatic pathways. This review highlights the advances made from studying the intrinsic pathway using gene-specific knockout animals and inhibitors in models of arterial and venous thrombosis. Development of inhibitors of activated FXI and FXII may reduce thrombosis with minimal increases in bleeding compared with current anticoagulant drugs.

The coagulation takes place in the hemostasis system and is a is hallmarked by a complex interplay of reactions between coagulation proteins. In the presence of a vascular breach, the conversion of prothrombin to thrombin leads to the formation of insoluble fibrin fibers that will stop bleeding and limit blood loss. Hemostasis is known to be disturbed in many diseases leading to hemorrhages or thrombosis. Despite the role of coagulation in hemostasis, recent evidences suggested that coagulation factors are involved in other (patho)physiological processes in the vasculature not necessarily marked by overt clotting, such as atherosclerosis and hypertension. Many direct (through protease activated receptors) or indirect effects of several coagulation factors are now well described. This review is focusing on the role of coagulation factors in the (dys)regulation of vascular function.

Competing Interests: Disclosure The authors report no conflicts of interest in this work.

Primary hemostasis begins with endothelial injury. VWF, produced by endothelial cells, binds to platelets and links them to subendothelial collagen. Platelet-derived ADP and thromboxane activate non-adhered platelets via their GPIIb/IIIa receptors, allowing these platelets to participate in platelet aggregation. Secondary hemostasis is initiated with the binding of factor VII to extravascular tissue factor (TF). Factors II, VII, IX and X are vitamin K-dependent factors. The role of vitamin K is to assist in the addition of gamma carboxylate groups to glutamic acids in the "GLA" domains of these factors.In vitro the intrinsic pathway is initiated when fresh whole blood is placed in a glass tube. The negative charge of the glass initiates the "contact pathway" where FXII is activated and then FXIa cleaves FIX to FIXa. The extrinsic pathway is triggered when tissue factor, phospholipid and calcium are added to plasma anticoagulated with citrate. In vitro, FVII is activated to FVIIa, and TF-FVIIa preferentially converts FX to FXa activating the common pathway.The prothrombin time is commonly used to monitor warfarin anticoagulant therapy. To correct for differences in reagent and instrument, the international normalized ratio was developed to improve standardization of PT reporting globally. The activated partial thromboplastin time (aPTT) is used to evaluate the intrinsic and common pathways of coagulation. The aPTT is useful clinically as a screening test for inherited and acquired factor deficiencies as well as to monitor unfractionated heparin therapy although the anti-Xa assay is now the preferred measure of the effects of unfractionated heparin. The Clauss assay is the most commonly performed fibrinogen assay and uses diluted plasma where clotting is initiated with a high concentration of reagent thrombin.The mixing study assists in the assessment of an abnormally prolonged PT or aPTT. An equal volume of citrated patient plasma is mixed with normal pooled plasma and the PT or aPTT are repeated on the 1:1 mix. Factor activity assays are most commonly performed as a one-stage assay. The patient's citrated plasma is diluted and mixed 1-to-1 with a single factor-deficient substrate plasma. A PT or aPTT is performed on the above mix, depending on the factor being tested.Factor inhibitors are antibodies that are most commonly diagnosed in male patients with severe hemophilia A (FVIII deficiency) where they are induced by factor replacement therapy.Factor inhibitors can also appear in the form of spontaneous autoantibodies in both male and female individuals who were previously well. This is an autoimmune condition called "acquired hemophilia."Most coagulation laboratories can measure the plasma concentration of VWF protein (VWF antigen) by an immunoturbidimetric technique. Testing the functional activity of VWF, utilizes the drug ristocetin.The state of multimerization of VWF is important and is assessed by electrophoresis on agarose gels. Type 2a and 2b VWD are associated with the lack of intermediate- and high molecular weight multimers.The antiphospholipid syndrome (APLS) is an acquired autoimmune phenomenon associated with an increased incidence of both venous and arterial thromboses, as well as fetal loss. Typically, there is a paradoxical prolongation of the aPTT in the absence of any clinical features of bleeding. This is the so-called "lupus anticoagulant (LA) effect." The laboratory definition of the APLS requires the presence of either a "lupus anticoagulant" or a persistent titer of antiphospholipid antibodies.There are now 2 broad classes of direct-acting oral anticoagulants (DOACs): [1] The oral direct thrombin inhibitors (DTIs) such as dabigatran; and [2] The oral direct factor Xa inhibitors such as rivaroxaban and apixaban. The PT and aPTT are variably affected by the DOACs and are generally unhelpful in monitoring their concentrations. Most importantly, a normal PT or aPTT does NOT exclude the presence of any of the DOACs., (© American Society for Clinical Pathology, 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Recent genome-wide association studies (GWAS) have identified numerous single nucleotide polymorphisms (SNPs) associated with coagulation system, including hemostatic factors and hematological phenotypes. However, few articles described the relationships between these SNPs and the risk of hemorrhagic stroke. The aim of our study was to evaluate the roles of these SNPs as risk factors and survival predictors for hemorrhagic stroke. Thirteen SNPs from GWAS in coagulation system were genotyped in a Chinese Han population including 1000 patients with hemorrhagic stroke (intracerebral hemorrhage, ICH = 743; subarachnoid hemorrhage, SAH = 257) and 1044 population-based controls. The associations between the genetics risk score (GRS) and risk of hemorrhagic stroke as well as post-stroke adverse outcomes were determined. No individual SNP was associated with the risk of hemorrhagic stroke. The GRS was calculated by summing the number of risk alleles of each SNP, and a total of 13 SNPs were included. Meanwhile, the GRS cutoffs values were defined to be close to quartiles or tertiles in control subjects. For quartiles, individuals with GRS about 8-9, 10-11, ≥12 had 1.28 (OR 1.28, 95% CI 0.98-1.68, p = 0.067)-, 1.36 (OR 1.36, 95% CI 1.04-1.79, p = 0.026)-, 1.53 (OR 1.53, 95% CI 1.13-2.07, p = 0.006)-fold increase in ICH risk compared to those with GRS ≤7, respectively; for tertiles, individuals with GRS about GRS 9-10, ≥11 had 0.98 (OR 0.98, 95% CI 0.78-1.23, p = 0.067)- and 1.26 (OR 1.26, 95% CI 1.00-1.59, p = 0.048)-fold increase in ICH risk compared to those with GRS ≤8, respectively. Further stratification analyses indicated that this association was only found in hypertensive ICH subjects. However, no statistical difference was found in the volume of hematoma, activities of daily living scale as well as hospital death in the ICH patients based on GRS values. Joint effects of SNPs associated with low coagulation factor levels might confer risk to ICH patients with hypertension. However, the clinical value on risk stratification and survival prediction was limited.

The biochemical characterisation of the proteolytic pathways that constitute blood coagulation was one of the most relevant achievements in biomedical research during the second half of the 20th century. Understanding these pathways was of crucial importance for improving global health through application in haemostasis and thrombosis pathologies. Immediately after the cloning of the genes corresponding to these proteins, mutations were discovered in them that were associated with imbalances in haemostasis. Later, the importance of coagulation pathways in other pathological processes was demonstrated, such as in atherosclerosis and inflammation, both essential processes involved in vascular disease. In the present review we evaluate the concepts that have allowed us to reach the integrated vision on coagulation that we have today. The thrombo-inflammation model encompassing these aspects includes a pivotal role for the proteases of the coagulation pathway as well as the regulatory proteins thereof. These concepts illustrate the importance of the coagulation cascade in cardiovascular pathology, not only in thrombotic processes, but also in atherosclerotic processes and in the response to ischaemia-reperfusion injury, making it a central mechanism in cardiovascular disease.

Purpose of Review: Recent advances in the understanding of the pathophysiological processes associated with traumatic haemorrhage and trauma-induced coagulopathy have resulted in improved outcomes for seriously injured trauma patients. However, a significant number of trauma patients still die from haemorrhage. This article reviews the various transfusion strategies utilized in the management of traumatic haemorrhage and describes the major haemorrhage protocol (MHP) strategy employed by an Australian trauma centre., Recent Findings: Few topics in trauma resuscitation incite as much debate and controversy as to what constitutes the 'ideal' MHP. There is a widespread geographical and institutional variation in clinical practice. Three strategies are commonly utilized; fixed ratio major haemorrhage protocol (FRMHP), viscoelastic haemostatic assay (VHA)-guided MHP and hybrid MHP. The majority of trauma centres utilize an FRMHP and there is high-level evidence to support the use of high blood product ratios. It can be argued that the FRMHP is too simplistic to be applied to all trauma patients and that the use of VHA-guided MHP with predominant factor concentrate transfusion can allow rapid individualized interventions. In between these two strategies is a hybrid MHP, combining early FRMHP with subsequent VHA-guided transfusion., Summary: There are advantages and disadvantages to each of the various MHP strategies and the evidence base to support one above another with any certainty is lacking at this time. One strategy cannot be considered superior to the other and the choice of MHP is dependent on interpretation of the current literature and local institutional logistical considerations. A number of exciting studies are currently underway that will certainly increase the evidence base and help inform clinical practice.

Increase of thrombus in the coronary arteries is positively correlated with the level of heat-shock protein 72 (HSP72) in the blood of patients with acute myocardial infarction (AMI). Platelet aggregation participates in thrombus formation on ruptured plaque in AMI. In this study, we aimed to clarify the role of HSP72 in thrombus formation by evaluating the effects of HSP72 on platelet aggregation. Platelet aggregation activities were measured in platelet-rich plasma obtained from male Sprague-Dawley rats with or without the platelet activators, such as adenosine diphosphate (ADP), collagen, thrombin receptor-activating peptide-6 (TRAP-6), ristocetin, and arachidonic acid. Changes in aggregation were estimated by the co-addition of recombinant HSP72 and anti-HSP72 antibodies. Our results showed that addition of HSP72 increased platelet aggregation in the presence of low concentrations of ADP, collagen, TRAP-6, ristocetin, and arachidonic acid. Increased platelet aggregation stimulated by ADP and HSP72 was reduced by the co-addition of anti-HSP72 antibodies. Thus, these findings suggested that HSP72 was released extracellularly in response to stress, promoting thrombus formation and AMI. Additionally, treatment with anti-HSP72 antibodies may control platelet aggregation induced by extracellular HSP72.

The hemostatic response requires the tightly regulated interaction of the coagulation system, platelets, other blood cells and components of the vessel wall at a site of vascular injury. The dysregulation of this response may result in excessive bleeding if the response is impaired, and pathologic thrombosis with vessel occlusion and tissue ischemia if the response is overly robust. Extensive studies over the past decade have sought to unravel the regulatory mechanisms that coordinate the multiple biochemical and cellular responses in time and space to ensure that an optimal response to vascular damage is achieved. These studies have relied in part on advances in in vivo imaging techniques in animal models, allowing for the direct visualization of various molecular and cellular events in real time during the hemostatic response. This review summarizes knowledge gained with these in vivo imaging and other approaches that provides new insights into the spatiotemporal regulation of coagulation and platelet activation at a site of vascular injury., (© 2015 International Society on Thrombosis and Haemostasis.)

It is well established that inflammation and thrombosis are intricately linked processes, and there is increasing evidence of the importance of their roles in activated complement in the pathogenesis of thromboembolism. The two systems are activated by similar stimuli simultaneously and interact, either directly or through biochemical mediators, to protect the host from microbial invasion. Diseases characterized by complement hyperactivity such as paroxysmal nocturnal hemoglobinuria and atypical hemolytic uremic syndrome have high rates of thrombosis. This review describes how disease processes where there is excessive complement activation leads to thrombosis, and the specific interactions between the complement and coagulation systems that lead to pathological thrombus formation., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Retinal ischemia and hemorrhage are hallmarks of worsening diabetic retinopathy, which can lead to neovascularization, macular edema, and severe vision loss. Although diabetes alters expression of clotting factors and their activities, and increases retinal microthromboses, the effects of thrombotic processes on the pathogenesis of diabetic retinopathy are not fully understood. In addition to the roles of coagulation and fibrinolytic cascades in thrombosis and hemostasis, components in these systems also mediate multiple effects on the vasculature that promote inflammation. Plasma kallikrein, thrombin, and urokinase are increased in diabetic retinopathy, and exert proinflammatory effects that contribute to retinal vascular dysfunction. The accumulation and activation of these and additional coagulation factors in the vitreous due to hemorrhage and chronic retinal injury in the diabetic retina may contribute to worsening of retinal inflammation and capillary dysfunction, which lead to retinal ischemia and edema. Further understanding of the role for specific coagulation factors in diabetic retinopathy may suggest new therapeutic opportunities for this vision-threatening disease., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Background: Hemostasis is a defense mechanism that enhances an organism's survival by minimizing blood loss upon vascular injury. In vertebrates, hemostasis has been evolving with the cardio-vascular and hemodynamic systems over the last 450 million years. Birds and mammals have very similar vascular and hemodynamic systems, thus the mechanism that blocks ruptures in the vasculature is expected to be the same. However, the speed of the process varies across vertebrates, and is particularly slow for birds. Understanding the differences in the hemostasis pathway between birds and mammals, and placing them in perspective to other vertebrates may provide clues to the genetic contribution to variation in blood clotting phenotype in vertebrates. We compiled genomic data corresponding to key elements involved in hemostasis across vertebrates to investigate its genetic basis and understand how it affects fitness., Results: We found that: i) fewer genes are involved in hemostasis in birds compared to mammals; and ii) the largest differences concern platelet membrane receptors and components from the kallikrein-kinin system. We propose that lack of the cytoplasmic domain of the GPIb receptor subunit alpha could be a strong contributor to the prolonged bleeding phenotype in birds. Combined analysis of laboratory assessments of avian hemostasis with the first avian phylogeny based on genomic-scale data revealed that differences in hemostasis within birds are not explained by phylogenetic relationships, but more so by genetic variation underlying components of the hemostatic process, suggestive of natural selection., Conclusions: This work adds to our understanding of the evolution of hemostasis in vertebrates. The overlap with the inflammation, complement and renin-angiotensin (blood pressure regulation) pathways is a potential driver of rapid molecular evolution in the hemostasis network. Comparisons between avian species and mammals allowed us to hypothesize that the observed mammalian innovations might have contributed to the diversification of mammals that give birth to live young.

Background: Exertional heat stroke (HS) with resultant acute liver failure (ALF) is a rare condition with high mortality. Diagnosis of ALF in the context of HS is confounded by numerous laboratory abnormalities related to multisystem organ dysfunction., Case Report: We present the case of a 20-year-old male athlete with exertional HS who developed ALF and was treated successfully with orthotopic liver transplantation. He remained well after 1 year with normal liver function and no permanent neurologic impairment. Diagnosis and treatment was guided by serial monitoring of coagulation factors and intracranial pressure (ICP)., Conclusions: Currently, there are no well validated prognostic tools that predict the need for or survival with orthotopic liver transplantation for HS. We propose that serial monitoring of coagulation factors and, when safe and feasible, ICP monitoring may help to guide clinical decision making in this context., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Anticoagulants are effective at preventing and treating thrombosis, but can cause bleeding. For decades, vitamin K antagonists (VKAs) have been the only available oral anticoagulants. The development of non-VKA oral anticoagulants (NOACs), which inhibit either factor Xa or thrombin stoichiometrically, has provided alternatives to VKAs for several indications. The results of recent large-scale randomised controlled trials comparing NOACs with VKAs for the prevention of stroke in patients with non-valvular atrial fibrillation (AF) have produced some unexpected results. As a group, NOACs showed similar efficacy as warfarin, but a reduced risk of major bleeding. The reduction in bleeding with NOACs was greatest with intracranial hemorrhage. In contrast, the relative risk of gastro-intestinal bleeding was increased with some NOACs. In this review, we explore the potential mechanisms as well as the implications of these organ-specific bleeding patterns.

The main purpose of anticoagulants is to diminish fibrin formation, thereby decreasing the risk of venous or arterial thrombosis. Vitamin K antagonist have been used for many decades in order to achieve reduced thrombotic risk, despite major drawbacks of this class of drugs such as cumbersome dossing and monitoring of anticoagulant status. To overcome these drawbacks of VKA, new classes of anticoagulants have been developed including oral anticoagulants for direct inhibition of either thrombin or factor Xa, which can be administrated in a fixed dose without monitoring. Coagulation factors can activate cellular protease-activated receptors, thereby inducing cellular processes as inflammation, apoptosis, migration, and fibrosis. Therefore, inhibition of coagulation proteases not only attenuates fibrin formation, but may also influence pathophysiological processes like vascular calcification and atherosclerosis. Animal models revealed that VKA therapy induced both intima and media calcification and accelerated plaque vulnerability, whereas specific and direct inhibition of thrombin or factor Xa attenuated atherosclerosis. In this review we provide an overview of old and new oral anticoagulants, as well discuss potential pleiotropic effects with regard to calcification and atherosclerosis. Although translation from animal model to clinical patients seems difficult at first sight, effort should be made to fully understand the clinical implications of long-term oral anticoagulant therapy on vascular side effects.

Endothelial cells express several types of integral membrane protein receptors, which upon interaction and activation by their specific ligands, initiate a signalling network that links extracellular cues in circulation to various biological processes within a plethora of cells in the vascular system. A small family of G-protein coupled receptors, termed protease-activated receptors (PAR1-4), can be specifically activated by coagulation proteases, thereby modulating a diverse array of cellular activities under various pathophysiological conditions. Thrombin and all vitamin K-dependent coagulation proteases, with the exception of factor IXa for which no PAR signalling has been attributed, can selectively activate cell surface PARs on the vasculature. Thrombin can activate PAR1, PAR3 and PAR4, but not PAR2 which can be specifically activated by factors VIIa and Xa. The mechanistic details of the specificity of PAR signalling by coagulation proteases are the subject of extensive investigation by many research groups worldwide. However, analysis of PAR signalling data in the literature has proved to be challenging since a single coagulation protease can elicit different signalling responses through activation of the same PAR receptor in endothelial cells. This article is focused on briefly reviewing the literature with respect to determinants of the specificity of PAR signalling by coagulation proteases with special emphasis on the mechanism of PAR1 signalling by thrombin and activated protein C in endothelial cells.

Tissue factor is the primary initiator of coagulation cascade and plays an essential role in haemostasis and thrombosis. In addition, tissue factor and coagulation proteases contribute to many cellular responses via activation of protease activated receptors. The heart is an organ with high levels of constitutive tissue factor expression. This review focuses on the role of tissue factor, coagulation proteases and protease activated receptors in heart haemostasis and the pathological heart remodelling associated with myocardial infarction, viral myocarditis and hypertension.

Background: Biological variation is usually estimated in healthy individuals during steady-state conditions. The aim of this study was to estimate the in-treatment biological variation of the International normalised ratio (INR) and to investigate to what extent the different levels of coagulation factors could explain this variation., Methods: Blood samples were collected from randomly included patients on warfarin treatment. INR was determined on a laboratory instrument (STA Compact(®)) and on three point-of-care instruments (Simple Simon(®)PT, CoaguChek(®)XS and INRatio(™)). The level of fibrinogen, and the activity of coagulation factors II, V, VII and X were determined., Results: The in-treatment within- and between-subject coefficients of variation of INR were dependent on the method and varied between 18 and 24% and 13 and 19%, respectively, and were reduced to 3.9-5.1% and 2.3-5.8%, after correction for coagulation factors which could explain 91-95% of the variance of INR., Conclusions: The in-treatment biological variation of INR was higher than reported for healthy individuals as well as patients in a steady-state condition, but by correcting for appropriate coagulation factors it was reduced. The association between INR and coagulation factors was different for the different PT methods mainly due to different sensitivity towards FII and FVII.

Stroke is now the leading cause of adult disability in the United States. Women are disproportionately affected by stroke. Women increasingly outnumber men in the elderly population, the period of highest risk for stroke. However, there is also a growing recognition that fundamental sex differences are present that contribute to differential ischemic sensitivity. In addition, gonadal hormone exposure can impact coagulation and fibrinolysis, key factors in the initiation of thrombosis. In this review we will discuss sex differences in stroke, with a focus on platelets, vascular reactivity and coagulation., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Recent studies have suggested that antithrombin (AT) could act as a significant physiologic regulator of FVIIa. However, in vitro studies showed that AT could inhibit FVIIa effectively only when it was bound to tissue factor (TF). Circulating blood is known to contain only traces of TF, at best. FVIIa also binds endothelial cell protein C receptor (EPCR), but the role of EPCR on FVIIa inactivation by AT is unknown. The present study was designed to investigate the role of TF and EPCR in inactivation of FVIIa by AT in vivo. Low human TF mice (low TF, ∼ 1% expression of the mouse TF level) and high human TF mice (HTF, ∼ 100% of the mouse TF level) were injected with human rFVIIa (120 µg kg(-1) body weight) via the tail vein. At varying time intervals following rFVIIa administration, blood was collected to measure FVIIa-AT complex and rFVIIa antigen levels in the plasma. Despite the large difference in TF expression in the mice, HTF mice generated only 40-50% more of FVIIa-AT complex as compared to low TF mice. Increasing the concentration of TF in vivo in HTF mice by LPS injection increased the levels of FVIIa-AT complexes by about 25%. No significant differences were found in FVIIa-AT levels among wild-type, EPCR-deficient, and EPCR-overexpressing mice. The levels of FVIIa-AT complex formed in vitro and ex vivo were much lower than that was found in vivo. In summary, our results suggest that traces of TF that may be present in circulating blood or extravascular TF that is transiently exposed during normal vessel damage contributes to inactivation of FVIIa by AT in circulation. However, TF's role in AT inactivation of FVIIa appears to be minor and other factor(s) present in plasma, on blood cells or vascular endothelium may play a predominant role in this process.

Coagulopathy is common in orthopedic surgery patients either due to acquired factors, such as surgery, trauma, medications, or hemorrhage. Perioperative monitoring of blood coagulation is critical to diagnose the causes of hemorrhage, guide hemostatic therapies, predict the risk of bleeding during surgical procedures, and reduce risk of postoperative cardiac and thromboembolic events. In contrast to previous interventions that measure specific portions of the clotting cascade (such as intrinsic or extrinsic pathways or platelet aggregation), "Point-of-care" coagulation monitoring devices assess the viscoelastic properties of whole blood. These techniques have the potential to measure the entire clotting process, starting with fibrin formation, clot retraction, and fibrinolysis. Furthermore, the coagulation status of patients is assessed in whole blood, allowing the plasmatic coagulation system to interact with platelets and red cells, and thereby providing useful additional information on platelet function. Improved monitoring of coagulopathy is particularly important as new anticoagulant drugs emerge that affect the clotting cascade in novel ways, including the inhibition of intrinsic and extrinsic pathways and platelet function. It is important for orthopedic surgeons to understand the pharmacology and reversal of these drugs in the perioperative setting. The purpose of this review is to review the current techniques to monitoring perioperative coagulopathy and to identify the manner in which novel anticoagulant medications affect the clotting cascade with particular interest in trauma and spine surgery.

Since the first report of the spontaneous appearance of venous thrombophlebitis as a sign of visceral cancer by Trousseau in 1865, many other studies have documented the existence of cancer-associated coagulation disorders. In this review, we describe the hypercoagulable state associated with colorectal cancer, from three perspectives: first, the incidence, risk factors and prevention of clinically symptomatic thromboembolic conditions associated with cancer, such as venous thromboembolism and arterial thrombosis; second, the association between hypercoagulable conditions, such as thrombocytosis, hyperfibrinogenemia, or D-dimer elevation, and the clinical progression and poor prognosis of cancer patients; third, the experimental approach to elucidate the role of various coagulation-related factors in the process of cancer progression, focusing specifically on the role of platelets and tissue factors.

Introduction: During the fluid phase of hemostasis, fibrinogen is converted into fibrin, but other hemostatic factors are required. Reference values of hemostatic factors are established by manufacturers producing reagents using individuals with a specific genetic background., Objective: To establish reference values for hemostatic factors in the Mexican indigenous and Mestizo populations., Material and Methods: We carried out a cross-sectional, descriptive study of healthy adult Mexicans. Clotting activity was evaluated using coagulometric assays. Blood donors were informed about the nature of the study and informed consent was obtained prior to blood being drawn. The protocol was approved by the Ethics Committee of our institution., Results: One hundred and twenty samples were assayed (60 females and 60 males). Fibrinogen was higher in mestizos and in females. Reference values for factor XII ranged from 40-170% in indigenous subjects and from 36-159% in mestizos. Factor VIII ranged from 57-160% in indigenous subjects and from 51-209% in mestizo subjects. Reference values for the other hemostatic factors were also clearly different from the commercial reference values. Reference values for hemostatic factors in the Mexican population are different from traditionally used commercial reference values. There were significant differences between indigenous and mestizo Mexicans in the concentration of hemostatic factors with a tendency among mestizos to have higher factor concentrations. Low levels of plasma factor XII are frequent and perhaps may represent a risk factor for thrombotic events. Using these reference values may individualize the reposition of factors in Mexican hemophiliac patients.

Objective: To determine if differing gauge (G) needles used for venipuncture altered the automated platelet count and coagulation profile (prothrombin time (PT) and activated partial thromboplastin time (aPTT)) in clinically healthy dogs., Design: Prospective, observational, randomised, clinical study., Methods: We enrolled 20 clinically healthy dogs. Blood was collected via direct venipuncture of the jugular veins with 21G, 23G and 25G needles in a random order. Automated haematology and automated coagulation times were performed on the blood samples. Values were analysed for differences among the needle gauges and also the order of sample collection., Results: No difference was found in the automated platelet count or automated coagulation times for the three needle gauges used or the order in which the samples were collected., Conclusion: Venipuncture can be performed with a 21G, 23G or 25G needle to obtain blood from dogs for automated platelet count and PT/aPTT measurement without affecting the results., (© 2014 Australian Veterinary Association.)

Several studies have suggested a role for blood coagulation proteins in tumour progression. Herein, we discuss (1) the activation of the blood clotting cascade in the tumour microenvironment and its impact on primary tumour growth; (2) the intravascular activation of blood coagulation and its impact on tumour metastasis and cancer-associated thrombosis; and (3) antitumour therapies that target blood-coagulation-associated proteins. Expression levels of the clotting initiator protein TF (tissue factor) have been correlated with tumour cell aggressiveness. Simultaneous TF expression and PS (phosphatidylserine) exposure by tumour cells promote the extravascular activation of blood coagulation. The generation of blood coagulation enzymes in the tumour microenvironment may trigger the activation of PARs (protease-activated receptors). In particular, PAR1 and PAR2 have been associated with many aspects of tumour biology. The procoagulant activity of circulating tumour cells favours metastasis, whereas the release of TF-bearing MVs (microvesicles) into the circulation has been correlated with cancer-associated thrombosis. Given the role of coagulation proteins in tumour progression, it has been proposed that they could be targets for the development of new antitumour therapies.

Vascular injury triggers two intertwined processes, platelet deposition and coagulation, and can lead to the formation of an intravascular clot (thrombus) that may grow to occlude the vessel. Formation of the thrombus involves complex biochemical, biophysical, and biomechanical interactions that are also dynamic and spatially-distributed, and occur on multiple spatial and temporal scales. We previously developed a spatial-temporal mathematical model of these interactions and looked at the interplay between physical factors (flow, transport to the clot, platelet distribution within the blood) and biochemical ones in determining the growth of the clot. Here, we extend this model to include reduction of the advection and diffusion of the coagulation proteins in regions of the clot with high platelet number density. The effect of this reduction, in conjunction with limitations on fluid and platelet transport through dense regions of the clot can be profound. We found that hindered transport leads to the formation of smaller and denser clots compared to the case with no protein hindrance. The limitation on protein transport confines the important activating complexes to small regions in the interior of the thrombus and greatly reduces the supply of substrates to these complexes. Ultimately, this decreases the rate and amount of thrombin production and leads to greatly slowed growth and smaller thrombus size. Our results suggest a possible physical mechanism for limiting thrombus growth.

Background: Fresh frozen plasma (FFP) should be thawed in a water bath at 30-37 degrees C. Suitable temperature, the prevention for bacterial contamination, and the efficiency of the process are necessary for a thawing procedure. In this study, we compared the clotting factor activity and thawing time in different thawing procedures; a water bath, the thermostatic thawing chamber (FP-40, Hokuyo ; Kawasumi, Japan), and the microwave system (Transfusio-therm 2000 AMCO; Zeipel, Germany)., Methods: Thawing time and the clotting factor activity (prothrombin time: PT, prothrombin time-international normalized ratio: PT-INR, activated partial thromboplastin time: APTT, fibrinogen, andfactors V) of thawed FFP-5 units were measured., Results: Thawing time using Transfusio-therm 2000 was 11.4 minutes, which was faster than that using the water bath and FP-40 of about 39.5 and 27.3 minutes, respectively (P<0.01). There were no differences between the three methods in terms of the clotting factors., Conclusions: The microwave system is useful in shortening the time safety, and maintaining the clotting factor activity in thawed FFP

Rationale: Efficient metastasis requires survival and adaptation of tumor cells to stringent conditions imposed by the extracellular milieu. Identification of critical survival signaling pathways in tumor cells might unveil novel targets relevant in disease progression., Objectives: To investigate the contribution of activated protein C (APC) and its receptor (endothelial protein C receptor [EPCR]) in animal models of lung cancer metastasis and in patients with lung adenocarcinoma., Methods: Signaling pathway triggered by APC/EPCR and its relevance in apoptosis was studied in vitro. Functional significance was assessed by silencing and blocking antibodies in several in vivo models of lung cancer metastasis in athymic nude Foxn1(nu) mice. We examined EPCR levels using a microarray dataset of 107 patients. Immunohistochemical analysis was performed in an independent cohort of 295 patients with lung adenocarcinoma., Measurements and Main Results: The effects of APC binding to EPCR rapidly triggered Akt and extracellular signal-regulated kinase signaling pathways, leading to attenuated in vitro apoptosis. In vivo, silencing of EPCR expression or blocking APC/EPCR interaction reduced infiltration in the target organ, resulting in impaired prometastatic activity. Moreover, overexpression of EPCR induced an increased metastatic activity to target organs. Analysis of clinical samples showed a robust association between high EPCR levels and poor prognosis, particularly in stage I patients., Conclusions: EPCR and its ligand APC promote cell survival that contributes to tumor cell endurance to stress favoring prometastatic activity of lung adenocarcinoma. EPCR/APC is a novel target of relevance in the clinical outcome of early-stage lung cancer.

Severe factor V (FV) deficiency (parahaemophilia) is a rare congenital hemorrhagic disorder characterized by very low or undetectable plasma FV levels and bleeding phenotype ranging from mild to severe. We evaluated whole blood (WB) rotation thromboelastometry (ROTEM) in parahaemophilia patients and the contribution of intraplatelets FV, if any, to clot formation. Standard ROTEM(®) assays were performed in WB from nine parahaemophilia patients and 50 healthy controls. In addition, platelets poor plasma from one parahaemophilia patient (PPP-Pt) or normal subjects (PPP-N) was reconstituted with washed platelets obtained either from one patient with parahaemophilia (Plts-Pt) or normal subjects (Plts-N) and ROTEM assays were performed in platelets rich plasma (PRP) samples. There was a prolongation of the WB clotting time (CT) in all assays in patients as compared with controls. However, maximum clot firmness (MCF) was similar in patients and controls. ROTEM in PPP-Pt showed both a prolongation of CT and a reduction of MCF as compared with PPP-N. The addition of either Plts-Pt or Plts-N to PPP-Pt resulted in similar increase in MCF and a decrease of CT which was more evident for PPP-Pt + Plts-N than PPP-Pt + Plts-Pt. In contrast, the addition of Plts-Pt or Plts-N to PPP-N had superimposable effects on both CT and MCF. In parahaemophilia patients, WB ROTEM(®) presents mainly with prolongation of CT and no relevant effect on MCF. Residual intraplatelets FV in parahaemophilia contributes significantly to thrombin generation as shown in artificially reconstituted PRP models., (© 2011 Blackwell Publishing Ltd.)

It has been known for more than half a century that the tumor microvasculature is hyperpermeable to plasma proteins. However, the identity of the leaky vessels and the consequences of vascular hyperpermeability have received little attention. This article places tumor vascular hyperpermeability in a broader context, relating it to (1) the low-level "basal" permeability of the normal vasculature; (2) the "acute," short-term hyperpermeability induced by vascular permeability factor/vascular endothelial growth factor (VPF/VEGF-A) and other vascular permeabilizing agents; and (3) the "chronic" hyperpermeability associated with longer-term exposure to agents such as VPF/VEGF-A that accompanies many types of pathological angiogenesis. Leakage of plasma protein-rich fluids is important because it activates the clotting system, depositing an extravascular fibrin gel provisional matrix that serves as the first step in stroma generation.

Hemostasis play an essentials role in protecting of vascular integrity and maintaining normal blood flow, and anatomically and functionally is entwined with the vasculature. The classic concept of atherosclerosis assigns a pivotal role to inflammation in the onset and progression of this disease. Accumulating data suggest an intimate cross-talk between hemostasis and inflammation, underscoring the role of both systems in many complex diseases, including atherothrombosis. An experimental data indicate that platelets and the coagulation system are important determinants of both atherogenesis and atherothrombosis. The hemostatic system is well known for its capacity to exert a multitude of actions on the vasculature. The current concept of a vulnerable plaque suggests that repeated plaque microruptures, followed by subclinical thrombosis, are critical for plaque growth and vulnerability.

We report the development of an aqueous buffer system tailored to the fluidic and hemodynamic requirements of our recently reported microfluidic platelet dynamic assay device, which uses hydrodynamic focusing to "shape" a blood sample into a thin flowing layer adjacent to its protein-functionalized surface. By matching the dynamic viscosity of whole blood (3.13 ± 0.08 mPa·s, from healthy donors), the selected buffer minimizes interfacial fluid mixing and better controls shear rate within the device, permitting platelet/protein-surface interaction assays with as little as 50 μL of whole blood. Buffers containing the viscosity-enhancing components bovine serum albumin (BSA), gelofusine/glycine, or histopaque (Ficoll gradient solution) were found not to activate platelets when incubated with blood at concentrations up to 50%, as assessed by flow cytometry quantitation of P-selectin expression and αIIbβ (3) activation. In contrast, glycerol-based buffer activated platelets (two-fold increase in P-selectin levels) at concentrations as low as 10% by volume. BSA- and gelofusine/glycine-based buffers were problematic in preparation and use, and therefore, were not used beyond initial characterization. The histopaque solution selected as the best choice for flow studies stabilizes sample contact with the device's thrombogenic surface, does not activate platelets, and does not interfere with the action of agonists added to deliberately activate platelets., (© 2011 IEEE)

Monocytes play an important role in hemostasis. In this study, the prothrombotic effects of the neuropeptide substance P (SP) on human monocytes through neurokinin-1 receptor (NK1-R) were characterized. SP upregulated monocyte tissue factor (TF), the major coagulation cascade stimulator, in a concentration and time dependent manner. Specific inhibition of NK1-R completely blocked TF expression. Monocytes stimulated by SP released cytokines and chemokines. When monocytes were stimulated with cytokines or chemokines, TF was expressed by the cytokines (GM-CSF, IFN-γ and TNF-α). Cytokines may play a major role in the mechanism of SP induced monocyte TF expression. NK1-R antagonists (NK1-RA) may have a role in developing novel therapeutic approaches to patients vulnerable to vaso-occlusive disorders., (Copyright © 2011 Elsevier B.V. All rights reserved.)

The blood coagulation system is a key survival mechanism that has developed to protect man against lethal bleeding. A second function of blood coagulation is its close interaction with immunity. The immune-mediated coagulation responses may broadly be regarded as an element of response to injury. Pathological coagulation responses, including thromboembolism and disseminated intravascular coagulation (DIC), could therefore be regarded as excessive immune responses to a vessel wall injury. Virchow's triad, which comprises changes in the components of the blood, the state of the vessel wall, and the blood flow, was originally proposed for venous thrombosis. However, lately it appears that the same principles can be applied to arterial thrombosis and even DIC. It has even been postulated that all forms of thrombosis may be part of a continuous spectrum of the same disease. Over the past few years, an accumulation of evidence has shown that the etiopathogenetic mechanisms behind venous and arterial thrombosis are quite similar. The traditional elements of Virchow's triad are found to apply to both arterial and venous thrombosis. Yet, nowadays more emphasis is placed on the vessel wall and vascular bed specificity and the interaction with inflammation and hypercoagulability. This narrative review will discuss recent advances in research on the possible interactions between coagulation, the vascular endothelium, and atherosclerosis as well as the consequences of such interactions for venous and arterial thrombosis.

The haemostatic system is a complex interaction between the vasculature, cellular components and plasma proteins that interact to maintain haemostasis in the healthy body. The haemostatic system can be further defined as primary, secondary and tertiary haemostasis to better define the interdependent mechanisms that combine to maintain haemostasis. The term 'developmental haemostasis' was first introduced by Maureen Andrews in the 1980s to describe the age-related physiological changes of the coagulation system as it develops progressively over time from fetal, neonatal, paediatric to adult and geriatric systems. This paper will focus on developmental changes in secondary haemostasis, that is, the plasma protein changes that occur with age, particularly during the fetal and neonatal period, when the changes are most marked compared to the adult system., (Copyright © 2011. Published by Elsevier Ltd.)