Showing papers in "Seminars in Thrombosis and Hemostasis in 2014"
TL;DR: VTE associated with hospitalization was the leading cause of disability-adjusted-life-years lost in low- and middle-income countries, and second in high- income countries, responsible for more DALYs lost than nosocomial pneumonia, catheter-related blood stream infections, and adverse drug events.
Abstract: Thrombosis is a common pathology underlying ischemic heart disease, ischemic stroke, and venous thromboembolism (VTE). The Global Burden of Disease Study 2010 (GBD 2010) documented that ischemic heart disease and stroke collectively caused one in four deaths worldwide. GBD 2010 did not report data for VTE as a cause of death and disability. We performed a systematic review of the literature on the global disease burden due to VTE in low-, middle-, and high-income countries. Studies from Western Europe, North America, Australia, and Southern Latin America (Argentina) yielded consistent results with annual incidences ranging from 0.75 to 2.69 per 1,000 individuals in the population. The incidence increased to between 2 and 7 per 1,000 among those 70 years of age or more. Although the incidence is lower in individuals of Chinese and Korean ethnicity, their disease burden is not low because of population aging. VTE associated with hospitalization was the leading cause of disability-adjusted-life-years (DALYs) lost in low- and middle-income countries, and second in high-income countries, responsible for more DALYs lost than nosocomial pneumonia, catheter-related blood stream infections, and adverse drug events. VTE causes a major burden of disease across low-, middle-, and high-income countries. More detailed data on the global burden of VTE should be obtained to inform policy and resource allocation in health systems, and to evaluate if improved utilization of preventive measures will reduce the burden.
427 citations
TL;DR: It is proposed that the rapid developments in the field of NETosis may provide new targets to combat the thrombotic consequences of cancer and perhaps even help to contain the disease itself.
Abstract: Neutrophils have long been known as innate immune cells that phagocytose and kill pathogens and mount inflammatory responses protecting the host from infection. In the past decades, new aspects of neutrophils have emerged unmasking their importance not only in inflammation but also in many pathological conditions including thrombosis and cancer. The 2004 discovery that neutrophils, upon strong activation, release decondensed chromatin to form neutrophil extracellular traps (NETs), has unveiled new avenues of research. Here, we review current knowledge regarding NETs in thrombosis, with a special focus on cancer-associated thrombosis as well as their potential role in cancer growth and metastasis. We discuss the prospective use of NET-specific biomarkers, such as citrullinated histone H3 and NET inhibitors, as tools to anticipate and fight cancer-associated thrombosis. We propose that the rapid developments in the field of NETosis may provide new targets to combat the thrombotic consequences of cancer and perhaps even help to contain the disease itself.
182 citations
TL;DR: The International Society on Haemostasis and Thrombosis (ISTH), and the British Committee for Standards in Haematology (BCSH) and the Clinical and Laboratory Standards Institute (CLSI) have recently updated their lupus anticoagulant detection guidelines, which represent significant moves toward engendering common practices.
Abstract: The International Society on Haemostasis and Thrombosis (ISTH) and the British Committee for Standards in Haematology (BCSH) have recently updated their lupus anticoagulant (LA) detection guidelines. The Clinical and Laboratory Standards Institute (CLSI) subsequently will publish its first LA guideline. General agreement exists on issues such as sample preparation, the use of dilute Russell viper venom time (dRVVT) in diagnostic repertoires, the use of normalized ratios, calculations to demonstrate phospholipid dependence, calculations to demonstrate inhibition, and interpretive reporting. The ISTH recommendation to employ only dRVVT and activated partial thromboplastin time is not mirrored in the BCSH and CLSI documents. The potential for false negatives in mixing tests is acknowledged by all panels, yet they remain mandated by ISTH as there are occasions when they are crucial to diagnostic accuracy. BCSH indicates that a negative mixing test need not exclude the presence of a LA, and CLSI reprioritizes test order to screen-confirm-mix, the latter being considered unnecessary in specific circumstances. Opinions in the guidelines differ on setting cutoff levels (i.e., 97.5th vs. 99th percentile for normally distributed data). All guidelines cover testing of anticoagulated patients, more detail being given by BCSH and CLSI, who suggest that Taipan snake venom time is a useful adjunct test in patients receiving vitamin K antagonists. Although complete agreement is not apparent, the guidelines represent significant moves toward engendering common practices.
126 citations
TL;DR: Breaking this vicious activation loop with nonspecific platelet inhibitors, such as aspirin, or by targeting specific sites on the activation cascade may offer a mean to reduce both the risks of development and progression of cancer and the risk of thrombosis.
Abstract: Platelets play a crucial role in the pathophysiological processes of hemostasis and thrombosis. Increasing evidence indicates that they fulfill much broader roles in balancing health and disease. The presence of tumor cells affects platelets both numerically, through a wide variety of mediators and cytokines, or functionally through tumor cell-induced platelet activation, the first step toward cancer-induced thrombosis. This induction results from signaling events through the different platelet receptors, or may be cytokine-mediated. Reciprocally, upon activation, the platelets will release a myriad of growth factors from their dense and α-granules and peroxisomes; these will directly impact tumor growth, tethering, and spread. A similar cross-talk is initiated between tumor microvesicles stimulating the platelets and platelet microparticles, promoting both thrombosis and tumor growth. A vicious loop of activation thereafter takes place. Platelets directly and indirectly promote tumor growth, and enable a molecular mimicry coating the malignant growth and allowing metastasizing cells to escape T-cell-mediated immunity and natural killer cell surveillance. Breaking this vicious activation loop with nonspecific platelet inhibitors, such as aspirin, or by targeting specific sites on the activation cascade may offer a mean to reduce both the risks of development and progression of cancer and the risk of thrombosis.
117 citations
TL;DR: The contribution of complement is discussed and its complex interaction with inflammation, coagulation, and the endothelium is highlighted across the emerging spectrum of complement-mediated thrombotic microangiopathies.
Abstract: Thrombotic microangiopathy (TMA) is a rare but severe disorder characterized by endothelial cell activation and thrombus formation. It manifests with the triad of hemolytic anemia, thrombocytopenia, and organ failure. Prompt diagnosis and treatment initiation are crucial for long-term outcome. TMA often manifests subsequent to infectious events, of which (enterohemorrhagic) Escherichia coli is the most frequently reported. TMA also occurs on the background of genetic/autoimmune defects in the complement system (atypical hemolytic uremic syndrome [aHUS]) and underlying conditions, such as pregnancy, transplantation, drugs, other glomerulopathies, vasculitides, or metabolic defects. Complement activation or defects in its regulation have now been described in an increasing number of acquired diseases with TMA. Coinciding with this expanding spectrum of complement-mediated diseases, the question arises which patients might benefit from a complement-targeted therapy. Success of therapy depends on the individual contribution of complement activation in disease pathogenesis. The advent of eculizumab, a monoclonal antibody that blocks terminal complement activation, has markedly improved outcome and quality of life in patients with aHUS. This review discusses the contribution of complement and highlights its complex interaction with inflammation, coagulation, and the endothelium. Treatment experiences focusing on eculizumab therapy are discussed in detail across the emerging spectrum of complement-mediated thrombotic microangiopathies.
115 citations
TL;DR: The genetic component of HUS is described, the lessons that are learned from the functional characterization of the aHUS-associated mutations, and the benefits of a comprehensive genetic analysis of the patients are described.
Abstract: Hemolytic uremic syndrome (HUS) is a rare, life-threatening disease characterized by thrombocytopenia, microangiopathic hemolytic anemia, and acute renal failure. The atypical form of HUS (aHUS), representing 5 to 10% of cases, lacks the association with infection by Shiga toxin producing Escherichia coli strains that characterizes the commonest clinical presentation of HUS. In the majority of aHUS cases, the disease results from the complement-mediated damage to the microvascular endothelium because of inherited defects in complement genes or autoantibodies against complement regulatory proteins. Incomplete penetrance of aHUS in carriers of mutations is common to all aHUS-associated complement genes and it is now established that the overall genetic predisposition to aHUS of an individual results from the combination of different inherited factors. Moreover, the patient's genotype influences the clinical evolution, the response to plasma therapies, and the recurrence after transplantation. Here, we describe the genetic component of aHUS, the lessons that we have learned from the functional characterization of the aHUS-associated mutations, and the benefits of a comprehensive genetic analysis of the patients.
115 citations
TL;DR: The changes in hemostasis markers measurable within many he mostasis laboratories are reviewed, and many of the important implications for clinical and laboratory practice are considered.
Abstract: The incidence of venous thromboembolism (VTE) is well recognized to increase with aging. Concurrently, the plasma concentrations of many coagulation factors (e.g., fibrinogen, factor [F] V, FVII, FVIII, and FIX) increase with aging, as does von Willebrand factor (VWF), thrombin generation, and platelet activation. Data are conflicting regarding age-related changes in the natural anticoagulants, including protein C, protein S, and antithrombin. Changes are also observed with components of the fibrinolytic pathway. All in all, aging is associated with a variety of hemostasis changes that on balance reflects a heightened procoagulant status compared with earlier age. It has to be recognized that as this occurs in the otherwise normal general population, this can also be considered a normal phenomenon of progressive life. An element of this heightened procoagulant status may reflect ongoing inflammatory processes, given some markers, notably FVIII and fibrinogen, are acute phase reactants. A variety of acquired prothrombotic risk factors (e.g., cancer, autoimmune disorders, and diabetes) also gradually develop with aging, some of which may induce profound abnormalities of hemostasis, and confound the age-related changes in hemostasis, as well as their influence on thrombotic risk. In this article, we review the changes in hemostasis markers measurable within many hemostasis laboratories, and consider many of the important implications for clinical and laboratory practice. Apart from representing an increased thrombotic risk, additional considerations entail the potential need (1) to utilize age-adjusted normal ranges (e.g., for D-dimer), (2) to consider the consequence on previous diagnoses (e.g., "mild type 1" von Willebrand disease [VWD], where VWF test results may "normalize" with aging), and (3) to consider the effect of these changes of risk factors on the (perceived) therapeutic efficacy of antithrombotic medications such as aspirin.
107 citations
TL;DR: Repeat testing of platelet function may be required, not only afterclusion of known antiplatelet medications but also potentially after exclusion of dietary substances/nutrients that could have plausibly affected initial test data.
Abstract: Cardiovascular disease (CVD) is the leading cause of death worldwide. Platelet activation and aggregation play an integral role in hemostasis and thrombosis. Diets and nutrients play a potential role in modifying CVD progression, particularly in platelet function, and have the potential of altering platelet function tests. Diets such as Mediterranean diet, high in omega-3 polyunsaturated fatty acids (PUFA), and vegetarian diets have inverse relationships with CVD. Dark chocolate, foods with low glycemic index, garlic, ginger, omega-3 PUFA, onion, purple grape juice, tomato, and wine all reduce platelet aggregation. Dark chocolate and omega-3 PUFA also reduce P-selectin expression. In addition, dark chocolate reduces PAC-1 binding and platelet microparticle formation. Berries inhibit platelet function (PFA-100). Energy drinks have been shown to increase platelet aggregation and caffeine increases platelet microparticle formation. Therefore, repeat testing of platelet function may be required, not only after exclusion of known antiplatelet medications but also potentially after exclusion of dietary substances/nutrients that could have plausibly affected initial test data.
103 citations
TL;DR: A better understanding of the molecular events leading to the progress of the hypercoagulable state in MPN patients may provide appropriate tools for the development of targeted therapies based on reversal of coagulopathy.
Abstract: Thrombotic events are very frequent and represent the main cause of morbidity and mortality in patients with Philadelphia chromosome–negative myeloproliferative neoplasms (MPNs), mainly polycythemia vera and essential thrombocythemia. Pathogenesis of blood clotting activation in these diseases is multifactorial, and it involves various abnormalities of platelets, erythrocytes, and leukocytes, as well as dysfunctions of endothelial cells. These include not only elevations in the counts of circulating blood cells, arising from the clonal proliferation of hematopoietic progenitor cells, but also modifications of several physiological/molecular properties. Patients with MPN can be stratified in “high-risk” or “low-risk” thrombotic categories according to the age and history of thrombosis. The most commonly used front-line drugs for the treatment of high-risk patients include hydroxyurea and interferon alpha, whereas in low-risk patients, primary antithrombotic prophylaxis with aspirin is used. Future research should be focused on the evaluation of the role of biomarkers in identifying MPN patients at higher risk of thrombosis, who may benefit from primary thromboprophylaxis. Finally, a better understanding of the molecular events leading to the progress of the hypercoagulable state in MPN patients may provide appropriate tools for the development of targeted therapies based on reversal of coagulopathy.
75 citations
TL;DR: The diagnostic approach to AHA is reviewed, assay-specific limitations are discussed and some of the challenges for future research are addressed, including why laboratory data failed to predict bleeding or response to treatment in AHA.
Abstract: Acquired hemophilia A (AHA) should be suspected in patients with a new onset of bleeding and an isolated prolongation of activated partial thromboplastin time. About 10% of patients do not bleed at the time of diagnosis, but are at risk of future bleeding, particularly during interventions or surgery. Diagnosis of AHA is confirmed by demonstrating markedly reduced factor VIII activity (FVIII:C) and neutralizing anti-FVIII antibodies, so-called inhibitors. Several limitations and pitfalls exist with the assays used to diagnose AHA. Interference can result from anticoagulants or lupus anticoagulant. The Bethesda assay used to measure inhibitor potency assumes a log-linear relationship between inhibitor concentration and effect on residual FVIII:C activity to allow exact quantification. However, this relationship is not present for the type 2 inhibitors typically seen in AHA. Therefore, this assay only provides a rough estimate of inhibitor potency. These limitations can explain, in part, why laboratory data, such as inhibitor potency, failed to predict bleeding or response to treatment in AHA. This article reviews the diagnostic approach to AHA, discusses assay-specific limitations and addresses some of the challenges for future research.
74 citations
TL;DR: Present data do not support routine thromboprophylaxis in brain tumor patients, and novel oral anticoagulants that directly inhibit thrombin such as dabigatran or factor Xa, including rivaroxaban and apixaban have several potential advantages; however, due to limited data in the cancer population, the use of these newer oral anti-cancer agents is not currently recommended.
Abstract: Venous thromboembolism (VTE) is common in patients with brain tumors, occurring in up to 30% of patients with high-grade glioma and up to 20% of those with brain metastasis and primary central nervous system (CNS) lymphoma. The risk is correlated with higher grade malignancies and is directly associated with the production of the potent procoagulant, tissue factor (TF). Upregulation of TF influences both the coagulation pathway and oncogenic signaling mechanisms important for cancer progression. The risk of intracranial hemorrhage with the use of anticoagulants complicates the management of VTE in patients with brain tumor. We discuss the recommended anticoagulants used for initial and long-term treatment of established VTE, including unfractionated heparin, low-molecular-weight heparin (LMWH), and warfarin. Therapeutic anticoagulation, particularly LMWH followed by secondary prophylaxis, is generally safe and effective in the treatment of VTE, including patients on antiangiogenic agents. Anticoagulation also reduces the risk of VTE during the perioperative period. However, despite the high risk of VTE throughout the course of disease, present data do not support routine thromboprophylaxis in brain tumor patients. Further investigation regarding the mechanisms underlying the hypercoagulable state of patients with brain tumors and the potential role of the factors and products of thrombogenesis as biomarkers for risk stratification will be useful in identification and management of patients at risk of developing VTE. Novel oral anticoagulants that directly inhibit thrombin such as dabigatran or factor Xa, including rivaroxaban and apixaban have several potential advantages; however, due to limited data in the cancer population, the use of these newer oral anticoagulants is not currently recommended for patients with malignancy and VTE. Recent studies have explored the role of anticoagulants as anticancer agents, which may contribute to cancer treatment in the future.
TL;DR: Plasminogen activator inhibitor-1 (PAI-1) levels are reported in age-associated clinical conditions including cardiovascular diseases, type 2 diabetes, obesity and inflammation, and its critical role in the regulation of aging and senescence has become evident.
Abstract: The average age of the US population continues to increase. Age is the most important determinant of disease and disability in humans, but the fundamental mechanisms of aging remain largely unknown. Many age-related diseases are associated with an impaired fibrinolytic system. Elevated plasminogen activator inhibitor-1 (PAI-1) levels are reported in age-associated clinical conditions including cardiovascular diseases, type 2 diabetes, obesity and inflammation. PAI-1 levels are also elevated in animal models of aging. While the association of PAI-1 with physiological aging is well documented, it is only recently that its critical role in the regulation of aging and senescence has become evident. PAI-1 is synthesized and secreted in senescent cells and contributes directly to the development of senescence by acting downstream of p53 and upstream of insulin-like growth factor binding protein-3. Pharmacologic inhibition or genetic deficiency of PAI-1 was shown to be protective against senescence and the aging-like phenotypes in kl/kl and Nω-nitro- l -arginine methyl ester–treated wild-type mice. Further investigation into PAI-1's role in senescence and aging will likely contribute to the prevention and treatment of aging-related pathologies.
TL;DR: Kidney biopsy in aHUS is often indistinguishable from other forms of thrombotic microangiopathy including enterohemorrhagic Escherichia coli-induced HUS and throm Bocytopenic purpura and shows thrombi in glomerular capillaries, mesangiolysis, and endothelial injury as evidenced by swelling and double contour formation along the glomersular capillary walls.
Abstract: Dysfunction of the alternative pathway of complement in the fluid phase results in deposition of complement factors in the renal glomeruli. This results in glomerular injury and an ensuing proliferative response. The term “C3 glomerulopathy” is used to define such an entity. It includes both C3 glomerulonephritis and dense deposit disease (DDD). Both C3 glomerulonephritis and DDD are characterized by a proliferative glomerulonephritis and bright glomerular C3 mesangial and capillary wall staining with the absence or scant staining for immunoglobulins (Ig). The two conditions are distinguished based on electron microscopy findings: mesangial and capillary wall deposits are noted in C3 glomerulonephritis, while ribbon-shaped dense osmiophilic intramembranous and mesangial deposits are noted in DDD. On the contrary, uncontrolled activation of the alternative pathway of complement on endothelial cell surface results in endothelial injury with an ensuing thrombotic microangiopathy, termed atypical hemolytic uremic syndrome (aHUS). Kidney biopsy in aHUS is often indistinguishable from other forms of thrombotic microangiopathy including enterohemorrhagic Escherichia coli–induced HUS and thrombotic thrombocytopenic purpura and shows thrombi in glomerular capillaries, mesangiolysis, and endothelial injury as evidenced by swelling and double contour formation along the glomerular capillary walls, with negative immunofluorescence studies for Ig and complement factors and no deposits on electron microscopy.
TL;DR: Experimental and clinical evidence now indicate that the initiation of coagulation in DIC is caused by tissue factor expression, which in combination with downregulated physiological anticoagulant pathways and impaired fibrinolysis leads to widespread fibrin deposition.
Abstract: Disseminated intravascular coagulation (DIC) is a syndrome characterized by systemic intravascular activation of coagulation, leading to a widespread deposition of fibrin in the circulation. There is ample experimental and pathological evidence that the fibrin deposition contributes to multiple organ failure. The massive and ongoing activation of coagulation may result in depletion of platelets and coagulation factors, which may cause bleeding (consumption coagulopathy). The syndrome of DIC is well known in the medical literature for centuries, although a more precise description of the underlying mechanisms had to await the 20th century. Initial ideas on a role of the contact activation system as the primary trigger for the systemic activation of coagulation as well as a presumed hyperfibrinolytic response in DIC have been found to be misconceptions. Experimental and clinical evidence now indicate that the initiation of coagulation in DIC is caused by tissue factor expression, which in combination with downregulated physiological anticoagulant pathways and impaired fibrinolysis leads to widespread fibrin deposition. In addition, an extensive bidirectional interaction between coagulation and inflammation may further contribute to the pathogenesis of DIC.
TL;DR: The discovery of "antihemophilic globulin" in the middle of the 20th century paved the way to the production of cryoprecipitate and then of FVIII and FIX concentrates, which revolutionized the treatment of hemophilia through the widespread adoption of home treatment and prophylaxis regimens, which dramatically improved the quality of life and life expectancy of persons with hemophilias during the past decade.
Abstract: Hemophilia A and B are rare inherited bleeding disorders characterized by the deficiency of coagulation factor VIII (FVIII) or factor IX (FIX). While the history of hemophilia dates back to the 2nd century AD, a modern description of hemophilia appeared only at the beginning of the 19th century. The discovery of “antihemophilic globulin” in the middle of the 20th century paved the way to the production of cryoprecipitate and then of FVIII and FIX concentrates. Barring the tragic consequences on the hemophilia community of the transmission of blood-borne viruses by nonvirus inactivated factor concentrates during the 1970s and 1980s, plasma-derived first and recombinant products later revolutionized the treatment of hemophilia through the widespread adoption of home treatment and prophylaxis regimens, which dramatically improved the quality of life and life expectancy of persons with hemophilia during the past decade. This article briefly reviews the most important stages of the management of hemophilia from the past century up to the present days.
TL;DR: Prophylaxis should be tailored considering individual risk factors for VTE, the stage of disease, the possible occurrence of thrombocytopenia, or renal insufficiency, and low-molecular-weight heparin (LMWH), fixed low-dose warfarin, and aspirin are acceptable strategies for antithrombotic proplylaxis.
Abstract: As for other malignancies, multiple myeloma is associated with an increased risk of venous thromboembolism (VTE) The incidence of VTE is estimated as 8 to 22 per 1,000 person-years; risk factors can be patient related (advanced age, other risk factors shared with the general population), disease related, and treatment related Disease-related risk factors can derive from the monoclonal component (rarely hyperviscosity or inhibition of natural anticoagulants) or hypercoagulability sustained by inflammatory cytokines (increased von Willebrand factor, factor VIII, fibrinogen levels, decreased protein S levels, acquired activated protein C resistance) The 1 to 2% baseline of incident VTE associated with conventional therapies as melphalan and prednisone is at least doubled by the use of doxorubicin or other chemotherapeutic agents The VTE rate associated with thalidomide or lenalidomide as monotherapy is similar, whereas combination with high-dose dexamethasone or multiple chemotherapeutic agents induces a multiplicative effect on the VTE rate up to 25% Low-molecular-weight heparin (LMWH), fixed low-dose warfarin, and aspirin are acceptable strategies for antithrombotic prophylaxis, reducing VTE to 5 to 8% in thalidomide-treated patients and 1 to 3% in lenalidomide-treated patients LMWH shows an advantage in efficacy not statistically significant Prophylaxis should be tailored considering individual risk factors for VTE, the stage of disease, the possible occurrence of thrombocytopenia, or renal insufficiency
TL;DR: The role of PAI-1 in the pathophysiology of aging and aging-associated disorders is highlighted as it can regulate the dissolution of fibrin and also inhibit the degradation of the extracellular matrix by reducing plasmin generation.
Abstract: Plasminogen activator inhibitor-1 (PAI-1), a principal inhibitor of fibrinolysis, is induced in thrombotic, fibrotic, and cardiovascular diseases, which in turn primarily afflict the older population. This induction of PAI-1 may play an important role in the pathology of these diseases as PAI-1 can regulate the dissolution of fibrin and also inhibit the degradation of the extracellular matrix by reducing plasmin generation. PAI-1 expression is elevated in aged individuals and is significantly upregulated in a variety of pathologies associated with the process of aging, including myocardial and cerebral infarction, vascular (athero) sclerosis, cardiac and lung fibrosis, metabolic syndromes (e.g., hypertension, hyperlipidemia, and insulin resistance), cancer, and inflammatory/stress responses. Thus, PAI-1 may play a critical role in the development of aging-associated pathological changes. In addition, PAI-1 is recognized as a marker of senescence and a key member of a group of proteins collectively known as the senescence-messaging secretome. In this review, we highlight the role of PAI-1 in the pathophysiology of aging and aging-associated disorders.
TL;DR: The administration of antibiotics in patients undergoing therapy with DOACs would seem to require accurate evaluation as to whether dose adjustments (personalized or antibiotic class driven) of the anticoagulant drug may be advisable, which might be facilitated by direct laboratory assessments of their anticoaggulant effect ex vivo.
Abstract: The recent development and marketing of novel direct oral anticoagulants (DOACs) represents a paradigm shift in the management of patients requiring long-term anticoagulation. The advantages of these compounds over traditional therapy with vitamin K antagonists include a reportedly lower risk of severe hemorrhages and the limited need for laboratory measurements. However, there are several scenarios in which testing should be applied. The potential for drug-to-drug interaction is one plausible but currently underrecognized indication for laboratory assessment of the anticoagulant effect of DOACs. In particular, substantial concern has been raised during Phase I studies regarding the potential interaction of these drugs with some antibiotics, especially those that interplay with permeability glycoprotein (P-gp) and cytochrome 3A4 (CYP3A4). A specific electronic search on clinical trials published so far confirms that clarithromycin and rifampicin significantly impair the bioavailability of dabigatran, whereas clarithromycin, erythromycin, fluconazole, and ketoconazole alter the metabolism of rivaroxaban in vivo. Because of their more recent development, no published data were found for apixaban and edoxaban, or for potential interactions of DOACs with other and widely used antibiotics. It is noteworthy, however, that an online resource based on Food and Drug Administration and social media information, reports several hemorrhagic and thrombotic events in patients simultaneously taking dabigatran and some commonly used antibiotics such as amoxicillin, cephalosporin, and metronidazole. According to these reports, the administration of antibiotics in patients undergoing therapy with DOACs would seem to require accurate evaluation as to whether dose adjustments (personalized or antibiotic class driven) of the anticoagulant drug may be advisable. This might be facilitated by direct laboratory assessments of their anticoagulant effect ex vivo.
TL;DR: Stx modulates complement regulator proteins leading to an impaired control and thus to enhanced complement activation and its implication in the pathogenesis of EHEC-induced HUS in vivo and whether complement blockage might be a therapeutic option still has to be elucidated.
Abstract: Hemolytic uremic syndrome (HUS), the most common cause of acute renal failure in childhood, is mainly caused by infection with Shiga toxin (Stx)-producing enterohemorrhagic Escherichia coli (EHEC). Besides its cytotoxic activity, Stx has been shown to interact with the complement system. Complement breakdown products have been found in serum of HUS patients suggesting complement activation and in vitro studies have demonstrated that Stx2 directly activates complement leading to formation of terminal complement complex. Furthermore, Stx2 has been found to bind to factor H (FH) resulting in a reduced cofactor activity on the cell surface. Binding of Stx2 has also been shown for other members of the FH family, namely FH-like protein 1 and FH-related protein 1. Both proteins also compete with FH for Stx binding, so that in the presence of FHR-1 less FH is bound to Stx and therefore more is available for endothelial cell protection. In addition, Stx2 has been demonstrated to downregulate the membrane-bound regulator CD59 on the surface of glomerular endothelial and tubulus epithelial cells on protein and at the mRNA level. In conclusion, Stx modulates complement regulator proteins leading to an impaired control and thus to enhanced complement activation. Its implication in the pathogenesis of EHEC-induced HUS in vivo and whether complement blockage might be a therapeutic option still has to be elucidated.
TL;DR: Given the complexity of disease pathogenesis in C3G, a patient-tailored approach including a comprehensive workup of complement abnormalities is necessary to evaluate the best treatment options and clinical trials assessing effectiveness of different complement blockers on the background of the individual complement profile are needed.
Abstract: C3 glomerulopathy (C3G) is a newly defined clinical entity comprising glomerular lesions with predominant C3 staining. Under this definition are now included membranoproliferative glomerulonephritis type II (dense deposit disease) and C3 glomerulonephritis. This group of glomerular diseases with a heterogeneous histological aspect shares a common pathogenesis, that is, a dysregulation of the alternative pathway of complement in the fluid phase leading to C3 deposition in the kidney. Recent advances have expanded our understanding of the underlying mechanisms, leading to the hypothesis that blocking the alternative complement pathway may be an effective treatment for C3Gs, as has been shown in other renal diseases driven by alternative pathway dysregulation, such as atypical hemolytic uremic syndrome. Results of 11 published cases of patients with different forms of C3G treated with eculizumab, an anti-C5 humanized monoclonal antibody, are encouraging. Given the complexity of disease pathogenesis in C3G, a patient-tailored approach including a comprehensive workup of complement abnormalities is necessary to evaluate the best treatment options. Clinical trials assessing effectiveness of different complement blockers on the background of the individual complement profile are needed.
TL;DR: In this article, a molecular linkages between von Willebrand factor (VWF) and the alternative complement pathway (AP) have been discovered, which may help to explain enigmatic clinical problems related to thrombotic microangiopathies, including some cases of refractory THC, TTP associated with only mild-modest deficiencies of ADAMTS-13, and the provocation (or exacerbation) of acute episodes in patients with the atypical hemolytic uremic syndrome, and Thrombosis in paroxysmal nocturnal
Abstract: Molecular linkages between von Willebrand factor (VWF) and the alternative complement pathway (AP) have recently been discovered. Endothelial cell (EC)-anchored ultra-large (UL) VWF multimeric strings function as an activating surface for the AP. C3 (in active C3b form) binds to the EC-anchored ULVWF strings, and promotes the assembly of C3bBb (C3 convertase) and C3bBbC3b (C5 convertase). These linkages may help to explain enigmatic clinical problems related to thrombotic microangiopathies, including some cases of refractory thrombotic thrombocytopenic purpura (TTP), TTP associated with only mild-modest deficiencies of ADAMTS-13, the provocation (or exacerbation) of acute episodes in patients with the atypical hemolytic uremic syndrome, and thrombosis in paroxysmal nocturnal hemoglobinuria. Recent experiments have also demonstrated that complement factor H performs a dual role: participating in regulation of the AP by binding to EC-anchored ULVWF strings; and functioning as a reductase to decrease the size of soluble VWF multimers.
TL;DR: C3G remains an ideal disease in which new complement therapies can be tested as they become available, and trials must include a comprehensive evaluation of each patient at the genetic and biomarker level so that individual responses to therapy can be predicted and understood.
Abstract: C3 glomerulopathy (C3G) defines a group of very rare renal diseases in which dysregulation of the alternative and terminal complement pathways plays a pivotal pathogenic role. Dysregulation is driven by genetic and/or acquired defects, with interindividual variability giving rise to two broad subtypes of C3G-dense deposit disease (DDD) and C3 glomerulonephritis (C3GN). Patient evaluation should include genetic testing and biomarker profiling of complement activity. There is currently no effective targeted treatment option for C3G and, as a consequence, a variety of supportive measures are used. C3G remains an ideal disease in which new complement therapies can be tested as they become available. Trials must include a comprehensive evaluation of each patient at the genetic and biomarker level so that individual responses to therapy can be predicted and understood in light of the degree of complement dysregulation and underlying pathology.
TL;DR: The risk factors, predictive biomarkers, and new guidelines, which recommend risk assessment of venous thromboembolism for all cancer patients are discussed.
Abstract: Patients with active malignancy are well-known to be at higher risk for venous thromboembolism (VTE). However, the risk of VTE varies considerably between patients and in the same patient over the natural history of their malignancy. Multiple clinical risk factors including primary site of cancer, use of systemic therapy including novel targeted agents, surgery, and hospitalization are known to increase the risk of VTE. Multiple candidate biomarkers including tissue factor, D-dimer, and soluble P-selectin have been identified. However, risk cannot be reliably predicted based on single risk factors or biomarkers. A risk assessment score has been validated in multiple populations and can identify patients at high risk for cancer-associated VTE. This review discusses the risk factors, predictive biomarkers, and new guidelines, which recommend risk assessment of VTE for all cancer patients. Potential applications of risk assessment, including targeted thromboprophylaxis, are also identified in this review.
TL;DR: The history of myocardial infarction diagnostics has gone through a continuous evolution over the past century, when several new discoveries have contributed to remarkably increase the number of patients appropriately diagnosed with this condition.
Abstract: The history of myocardial infarction (MI) diagnostics has gone through a continuous evolution over the past century, when several new discoveries have contributed to remarkably increase the number of patients appropriately diagnosed with this condition. The tale "of MIs and Men" displays rather a long history, since atherosclerosis was found to be present in humans several centuries before modern civilization and the identification of the most prevalent risk factors. It was only at the end of the 19th century and at the beginning of the 20th century that the physicians acknowledged that MI is principally sustained by coronary thrombosis, and that the clinical picture of MI could be subsequently confirmed at autopsy. With the first description of the electrocardiogram (ECG) in the 1910s and 1920s, the history of modern MI diagnostics really began. Additional important discoveries followed, which are mainly represented by radiography, echocardiography, computed tomography, and magnetic resonance imaging of the heart. Another major breakthrough occurred at the down of the third millennium, with the development of commercial immunoassays for the measurement of cardiac troponin I and T, which represent now the cornerstones for identifying any kind of myocardial injury, thus including MI. The major advancements in the understanding of MI pathophysiology and the progressive introduction of efficient diagnostic tools will be described and discussed in this narrative historical review.
TL;DR: The literature on the biological and clinical features of CFH-Ab HUS are reviewed, therapeutic options are discussed, and information on clinical features and outcome in children is limited.
Abstract: The presence of circulating autoantibodies, primarily to complement factor H antibodies (CFH-Abs) in plasma characterizes the autoimmune form of atypical hemolytic uremic syndrome (aHUS). This acquired form of aHUS defines a distinct subgroup of aHUS patients, which requires diagnostic and treatment approaches in part different from those of the genetically defined forms. The mechanisms leading to CFH-Ab production and disease onset are not completely understood, but CFH-Ab HUS seems to be secondary to a combination of genetic predisposition and environmental factors. Early diagnosis of this specific aHUS entity is important, as prompt induction of plasma exchange and concomitant immunosuppression leads to a favorable outcome. Nevertheless, information on clinical features and outcome in children is limited. Here, we review the literature on the biological and clinical features of CFH-Ab HUS and discuss therapeutic options.
TL;DR: The purpose of this narrative review is to explore the history of phenotypic VWD diagnostics, with a focus on laboratory milestones from the past as well highlighting recent and ongoing innovations, and ongoing challenges and possible solutions.
Abstract: von Willebrand disease (VWD) is a disorder characterized by deficiency of, or defects in, von Willebrand factor (VWF). VWD was originally identified by Erik Adolf von Willebrand, who in early 1924 investigated a large family suffering from a bleeding disorder that seemed to differ from hemophilia. Erik von Willebrand undertook some initial laboratory investigations to conclude the involvement of a plasma factor, the lack of which prolonged the bleeding time, but failed to impair coagulation times and clot retraction. By the end of the 1960s, VWD was accepted as a combined deficiency of factor VIII (FVIII) and another plasma factor responsible for normal platelet adhesion. Just how these two functions were related to each other was less clear and the diagnostic tests available at the time were poorly reproducible, cumbersome, and unreliable; thus, VWD was poorly delineated from other coagulation and platelet disorders. The early 1970s saw a revolution in diagnostics when ristocetin was identified to induce platelet aggregation, and this formed the basis of the first consistent and reliable VWF "activity" test, permitting quantification of the platelet adhesive function missing in VWD. Concurrently, immunoprecipitating techniques specific for VWF were defined, and the application of such technologies permitted a clearer understanding of both VWF and VWD heterogeneity. Continued exploration of the structure and function of VWF contributed greatly to the understanding of platelet physiology, ligand receptor interaction and pathways of cellular interaction and activation. Recently, additional assays evaluating other functions of VWF, including collagen binding, platelet glycoprotein Ib binding, and FVIII binding, have improved the diagnosis of VWD. The purpose of this narrative review is to explore the history of phenotypic VWD diagnostics, with a focus on laboratory milestones from the past as well highlighting recent and ongoing innovations, and ongoing challenges and possible solutions.
TL;DR: There is no evidence for a beneficial use in the diarrheal phase and earlier warnings that antibiotic therapy at this stage may actually increase the likelihood of HUS remain unrefuted, but the use of a complement blocker in severe disease may actually make the difference between favorable or detrimental outcome.
Abstract: Treatment of enterohemorrhagic Escherichia coli-induced hemolytic uremic syndrome (eHUS) still mostly relies on supportive intensive care regimens. Antibiotic treatment, as administered to eHUS patients during the 2011 O104:H4 outbreak, may reduce the shedding period, but this may apply only to this particular strain. In any case, there is no evidence for a beneficial use in the diarrheal phase and earlier warnings that antibiotic therapy at this stage may actually increase the likelihood of HUS remain unrefuted. Plasma exchange, a frequently chosen therapy in acute atypical HUS, was not beneficial for the outbreak patients and a prospective study of 274 pediatric eHUS patients even indicates a poorer long-term outcome. As eHUS is a disease where complement plays a pathophysiological role and individual beneficial treatments had been published, eculizumab was broadly administered during the outbreak, in particular to severely ill patients. The equally good outcome of treated versus untreated patients obviously does not allow a clear-cut statement, but rather points toward an advantageous use, at least for the severe cases. Although the role of complement should not be overestimated, the use of a complement blocker--not necessarily being a therapeutic option for uncomplicated eHUS--in severe disease may actually make the difference between favorable or detrimental outcome.
TL;DR: The search for the components of the platelet surface that mediate platelet adhesion and platelet aggregation began for earnest in the late 1960s when electron microscopy demonstrated the presence of a carbohydrate-rich, negatively charged outer coat that was called the "glycocalyx".
Abstract: The search for the components of the platelet surface that mediate platelet adhesion and platelet aggregation began for earnest in the late 1960s when electron microscopy demonstrated the presence of a carbohydrate-rich, negatively charged outer coat that was called the “glycocalyx.” Progressively, electrophoretic procedures were developed that identified the major membrane glycoproteins (GP) that constitute this layer. Studies on inherited disorders of platelets then permitted the designation of the major effectors of platelet function. This began with the discovery in Paris that platelets of patients with Glanzmann thrombasthenia, an inherited disorder of platelet aggregation, lacked two major GP. Subsequent studies established the role for the GPIIb-IIIa complex (now known as integrin αIIbβ3) in binding fibrinogen and other adhesive proteins on activated platelets and the formation of the protein bridges that join platelets together in the platelet aggregate. This was quickly followed by the observation that platelets of patients with the Bernard–Soulier syndrome, with macrothrombocytopenia and a distinct disorder of platelet adhesion, lacked the carbohydrate-rich, negatively charged, GPIb. It was shown that GPIb, through its interaction with von Willebrand factor, mediated platelet attachment to injured sites in the vessel wall. What follows is a personal reflection on the studies that were performed in the early pioneering days.
TL;DR: The sticky platelet syndrome was recognized as a distinct disorder in 1983 by Holiday and further characterized in the 1980s and 1990s, with Mammen and Bick providing the key findings.
Abstract: The sticky platelet syndrome (SPS) is a thrombophilic qualitative platelet disorder with familial occurrence and autosomal dominant trait, characterized by increased in vitro platelet aggregation after low concentrations of adenosine diphosphate and/or epinephrine. Its clinical manifestation includes arterial thrombosis, pregnancy complications (fetal growth retardation and fetal loss), and less often venous thromboembolism. SPS was considered to be a rare thrombophilic disorder, but it can be found relatively often as a cause of unexplained thrombosis, particularly among patients with arterial thrombosis such as stroke. The syndrome was recognized as a distinct disorder in 1983 by Holiday and further characterized in the 1980s and 1990s, with Mammen and Bick providing the key findings. Although recognized for more than 30 years, significant issues, namely the syndrome's etiology, inheritance, and epidemiology, remain unclear. The aim of the first part of this review is to summarize the previous 35 years of the research into, and to provide a brief historical account of, SPS. The history section is focused particularly on the work of two most prominent investigators: Eberhard F. Mammen and Rodger L. Bick. The second part summarizes the present understanding of the syndrome and outlines unresolved issues and the trends in which the future research is likely to continue.
TL;DR: Approaches that have been used in the past to achieve harmonization among aPL immunoassays as well as the ongoing efforts of the APLA task force are discussed.
Abstract: The measurement of antiphospholipid antibodies (aPL) has been an important aspect of antiphospholipid syndrome (APS) characterization since the disease was first described in the 1980s. Despite significant efforts geared toward the standardization of immunoassays that measure anticardiolipin antibodies and anti-β2-glycoprotein I spanning three decades, there are still reports of significant interassay and interlaboratory variation in the results of these assays. At the recent 13th International Congress on Antiphospholipid Antibodies (APLA 2010, April 13-16, 2010, Galveston, TX), a task force composed of internationally recognized experts in the field of APS was formed to address these issues. In this review, we discuss approaches that have been used in the past to achieve harmonization among aPL immunoassays as well as the ongoing efforts of the APLA task force. Our review also highlights the importance of cutoff determination in aPL assays and the clinical significance of positive aPL results of varying magnitudes.