Science.gov

Sample records for 2a von willebrand

  1. von Willebrand Disease

    MedlinePlus

    ... from the NHLBI on Twitter. What Is Von Willebrand Disease? Von Willebrand disease (VWD) is a bleeding disorder. ... while hemophilia mainly affects males. Types of von Willebrand Disease The three major types of VWD are called ...

  2. Living with von Willebrand Disease

    MedlinePlus

    ... from the NHLBI on Twitter. Living With von Willebrand Disease If you have von Willebrand disease (VWD), you ... that they get tested too. Pregnancy and von Willebrand Disease Pregnancy can be a challenge for women who ...

  3. von Willebrand Disease.

    PubMed

    Swami, Arjun; Kaur, Varinder

    2016-01-01

    von Willebrand disease (vWD) is the most common inherited disorder of hemostasis and comprises a spectrum of heterogeneous subtypes. Significant advances have been made in understanding von Willebrand factor ( vWF) gene mutations, resultant physiologic deficits in the vWF peptide, and their correlation to clinical presentation. Diagnostic tests for this disorder are complex, and interpretation requires a thorough understanding of the underlying pathophysiology by the practicing physician. The objective of this review is to summarize our current understanding of pathophysiology, laboratory investigations, and evolving treatment paradigm of vWD with the availability of recombinant von Willebrand factor.

  4. Von Willebrand disease

    MedlinePlus

    ... done to diagnose this disease include: Bleeding time Blood typing Factor VIII level Platelet function analysis Platelet count Ristocetin cofactor test Von Willebrand factor specific tests ... invasive procedure. Blood plasma or certain factor VIII preparations may also ...

  5. Type 2M and Type 2A von Willebrand Disease: Similar but Different.

    PubMed

    Favaloro, Emmanuel J; Pasalic, Leonardo; Curnow, Jennifer

    2016-07-01

    Analogous to the differentiation between hemophilia A and B, respectively, reflecting deficiency in factor VIII (FVIII) and FIX, and increasing being recognized as reflecting clinically different disorders, types 2A and 2M von Willebrand disease (VWD) can also be shown to express both similarities and differences in their prevalence, genetic defects, laboratory test results, clinical features, and treatment responses. In this narrative review, we explore these two "subtypes" of type 2 VWD, identifying parallels and dissimilarities in various aspects of their presentation to clinicians and to scientists/laboratories. This differential will become increasingly important as we strive to provide personalized approaches to future management of patients with VWD, particularly in the emerging landscape of recombinant von Willebrand factor.

  6. von Willebrand factor and von Willebrand disease.

    PubMed

    Matsui, Taei; Hamako, Jiharu

    von Willebrand factor (VWF) has two major roles in hemostasis, as a form of molecular glue which functions in platelet plug formation and as a protective transporter for coagulation factor VIII (FVIII). VWF shows a multimeric chain structure composed of 270 kDa subunits containing binding domains for FVIII, platelet and collagens. Biosynthesis, storage, secretion of VWF and the cleavage process by ADAMTS13 (a disintegrin-like and metalloproteinase with thrombospondin type 1 repeats 13) regulating VWF activity have been elucidated. von Willebrand disease (VWD) is an autosomal bleeding disorder, first documented in 1926, caused by quantitative or qualitative deficiency of VWF. The classification and molecular pathogenesis of VWD have been developed during a 90-year period based on clinical laboratory analysis of VWF, and structure-function analysis of mutant VWF with amino acid substitutions (genetic changes). VWF is a unique and very large multifunctional plasma protein, the hemostatic activity of which is dynamically regulated by physiological shear stress in the blood stream.

  7. Structural basis of type 2A von Willebrand disease investigated by molecular dynamics simulations and experiments.

    PubMed

    Interlandi, Gianluca; Ling, Minhua; Tu, An Yue; Chung, Dominic W; Thomas, Wendy E

    2012-01-01

    The hemostatic function of von Willebrand factor is downregulated by the metalloprotease ADAMTS13, which cleaves at a unique site normally buried in the A2 domain. Exposure of the proteolytic site is induced in the wild-type by shear stress as von Willebrand factor circulates in blood. Mutations in the A2 domain, which increase its susceptibility to cleavage, cause type 2A von Willebrand disease. In this study, molecular dynamics simulations suggest that the A2 domain unfolds under tensile force progressively through a series of steps. The simulation results also indicated that three type 2A mutations in the C-terminal half of the A2 domain, L1657I, I1628T and E1638K, destabilize the native state fold of the protein. Furthermore, all three type 2A mutations lowered in silico the tensile force necessary to undock the C-terminal helix α6 from the rest of the A2 domain, the first event in the unfolding pathway. The mutations F1520A, I1651A and A1661G were also predicted by simulations to destabilize the A2 domain and facilitate exposure of the cleavage site. Recombinant A2 domain proteins were expressed and cleavage assays were performed with the wild-type and single-point mutants. All three type 2A and two of the three predicted mutations exhibited increased rate of cleavage by ADAMTS13. These results confirm that destabilization of the helix α6 in the A2 domain facilitates exposure of the cleavage site and increases the rate of cleavage by ADAMTS13.

  8. von Willebrand Disease (For Parents)

    MedlinePlus

    ... problems because the levels or functioning of these blood components needed for clotting are abnormal. continue Types of von Willebrand Disease As with many conditions, there are various forms ... of von Willebrand factor in the blood is reduced; the level of factor VIII also ...

  9. von Willebrand disease type 2A phenotypes IIC, IID and IIE: A day in the life of shear-stressed mutant von Willebrand factor.

    PubMed

    Brehm, M A; Huck, V; Aponte-Santamaría, C; Obser, T; Grässle, S; Oyen, F; Budde, U; Schneppenheim, S; Baldauf, C; Gräter, F; Schneider, S W; Schneppenheim, R

    2014-07-03

    The bleeding disorder von Willebrand disease (VWD) is caused by mutations of von Willebrand factor (VWF), a multimeric glycoprotein essential for platelet-dependent primary haemostasis. VWD type 2A-associated mutations each disrupt VWF biosynthesis and function at different stages, depending on the VWF domain altered by the mutation. These effects cause considerable heterogeneity in phenotypes and symptoms. To characterise the molecular mechanisms underlying the specific VWF deficiencies in VWD 2A/IIC, IID and IIE, we investigated VWF variants with patient-derived mutations either in the VWF pro-peptide or in domains D3 or CK. Additionally to static assays and molecular dynamics (MD) simulations we used microfluidic approaches to perform a detailed investigation of the shear-dependent function of VWD 2A mutants. For each group, we found distinct characteristics in their intracellular localisation visualising specific defects in biosynthesis which are correlated to respective multimer patterns. Using microfluidic assays we further determined shear flow-dependent characteristics in polymer-platelet-aggregate formation, platelet binding and string formation for all mutants. The phenotypes observed under flow conditions were not related to the mutated VWF domain. By MD simulations we further investigated how VWD 2A/IID mutations might alter the ability of VWF to form carboxy-terminal dimers. In conclusion, our study offers a comprehensive picture of shear-dependent and shear-independent dysfunction of VWD type 2A mutants. Furthermore, our microfluidic assay might open new possibilities for diagnosis of new VWD phenotypes and treatment choice for VWD patients with shear-dependent VWF dysfunctions that are currently not detectable by static tests.

  10. Von Willebrand factor processing.

    PubMed

    Brehm, Maria A

    2017-01-31

    Von Willebrand factor (VWF) is a multimeric glycoprotein essential for primary haemostasis that is produced only in endothelial cells and megakaryocytes. Key to VWF's function in recruitment of platelets to the site of vascular injury is its multimeric structure. The individual steps of VWF multimer biosynthesis rely on distinct posttranslational modifications at specific pH conditions, which are realized by spatial separation of the involved processes to different cell organelles. Production of multimers starts with translocation and modification of the VWF prepropolypeptide in the endoplasmic reticulum to produce dimers primed for glycosylation. In the Golgi apparatus they are further processed to multimers that carry more than 300 complex glycan structures functionalized by sialylation, sulfation and blood group determinants. Of special importance is the sequential formation of disulfide bonds with different functions in structural support of VWF multimers, which are packaged, stored and further processed after secretion. Here, all these processes are being reviewed in detail including background information on the occurring biochemical reactions.

  11. Treatment of von Willebrand Disease.

    PubMed

    Curnow, Jennifer; Pasalic, Leonardo; Favaloro, Emmanuel J

    2016-03-01

    Congenital von Willebrand disease (VWD) and acquired von Willebrand syndrome (AVWS) reflect conditions caused by von Willebrand factor (VWF) deficiency and/or defects. VWD is the most common inherited bleeding disorder and AVWS arises from a variety of causes. Since VWF stabilizes and protects factor VIII (FVIII) in the circulation, this is also reduced in many patients with VWD. The treatment of VWD and AVWS therefore primarily entails replacement of VWF, and sometimes FVIII, to protect against bleeding. This may entail the use of VWF concentrates (currently plasma-derived) and/or FVIII concentrates (currently plasma-derived or more increasingly recombinant forms), and/or desmopressin to release endogenous VWF in subgroups of patients. For AVWS additional treatment of the underlying condition is also required. Adjunct therapies include antifibrinolytics. Globally, various formulations exist for both VWF and FVIII concentrates and are differentially available based on manufacturer marketing or regulatory approvals/clearances in different geographies. Also, guidelines for treatment of VWD vary for different localities and recombinant VWF is undergoing clinical trials. The current review provides an overview of the treatment of VWD as currently practiced in developed countries, and also provides a glimpse towards the future.

  12. Alloantibodies in von Willebrand disease.

    PubMed

    James, Paula D; Lillicrap, David; Mannucci, Pier M

    2013-08-01

    The development of alloantibodies against von Willebrand factor (VWF) represents a rare but serious complication of treatment of von Willebrand disease (VWD), occurring in ~5% to 10% of type 3 VWD patients. Affected patients can present with a range of symptoms, including lack or loss of hemostatic response to infused VWF concentrates up to anaphylactic reactions in rare cases. It is classically reported in multitransfused patients and occurs most frequently in patients with partial or complete VWF gene deletions. A positive family history of anti-VWF antibodies also appears to be a risk factor. There is a lack of standardization of laboratory methods for antibody identification and characterization. Issues of variability in laboratory approaches as well as the rarity of the complication act as a barrier to future studies. Recombinant factor VIII as well as bypassing agents and immune tolerance have been reported as effective treatments; however, aside from case reports, little exists in the literature to guide management. The imminent clinical availability of recombinant VWF has prompted a resurgence of interest in this area. Additional study is warranted to address the deficiencies in our understanding of this treatment complication.

  13. Clearance of von Willebrand factor.

    PubMed

    Denis, Cécile V; Christophe, Olivier D; Oortwijn, Beatrijs D; Lenting, Peter J

    2008-02-01

    The life cycle of von Willebrand factor (VWF) comprises a number of distinct steps, ranging from the controlled expression of the VWF gene in endothelial cells and megakaryocytes to the removal of VWF from the circulation. The various aspects of VWF clearance have been the objects of intense research in the last few years, stimulated by observations that VWF clearance is a relatively common component of the pathogenesis of type 1 von Willebrand disease (VWD). Moreover, improving the survival of VWF is now considered as a viable therapeutic strategy to prolong the half-life of factor VIII in order to optimise treatment of haemophilia A. The present review aims to provide an overview of recent findings with regard to the molecular basis of VWF clearance. A number of parameters have been identified that influence VWF clearance, including its glycosylation profile and a number of VWF missense mutations. In addition, in-vivo studies have been used to identify cells that contribute to the catabolism of VWF, providing a starting point for the identification of receptors that mediate the cellular uptake of VWF. Finally, we discuss recent data describing chemically modification of VWF as an approach to prolong the half-life of the VWF/FVIII complex.

  14. [Determination of von Willebrand factor multimers in Mexican population].

    PubMed

    Hernández-Zamora, Edgar; Zavala-Hernández, Cesar; Viveros-Sandoval, Martha Eva; Ochoa-Rico, Angeles; Martínez-Murillo, Carlos; Reyes-Maldonado, Elba

    2014-01-01

    Antecedentes: la enfermedad de von Willebrand es un padecimiento hereditario en el que la estructura, función y concentración del factor de von Willebrand están alteradas y, en consecuencia, también la interacción plaqueta-factor de von Willebrand-endotelio. En México no hay registros epidemiológicos de la enfermedad, sólo se han efectuado algunos estudios aislados desde el punto de vista clínico y hematológico. Material y métodos: estudio retrospectivo efectuado en 155 mexicanos mestizos, 75 de ellos con diagnóstico presuntivo de enfermedad de von Willebrand, 15 con sospecha de hemofilia A y 65 donadores sanos (testigos). Se realizaron pruebas: básicas de coagulación, especiales y de clasificación: análisis de la composición multimérica. Resultados: 15 pacientes se diagnosticaron con hemofilia A; de los 75 sujetos con sospecha de enfermedad de von Willebrand se diagnosticaron 50 de la manera siguiente: tipo 1 (62%), tipo 2 (22%) [subtipos: 2A (14%), 2B (2%) y 2N (6%)] y tipo 3 (16%). Conclusión: el análisis de los multímeros del factor de von Willebrand es un método que cumple con las características adecuadas para el diagnóstico de la enfermedad de von Willebrand, por lo que es necesario implementar esta metodología para su estudio y mejorar su diagnóstico específico.

  15. Interactions of von Willebrand factor and ADAMTS13 in von Willebrand disease and thrombotic thrombocytopenic purpura.

    PubMed

    Budde, U; Schneppenheim, R

    2014-01-01

    The function of von Willebrand factor (VWF), a huge multimeric protein and a key factor in platelet dependent primary haemostasis, is regulated by its specific protease ADAMTS13. The ADAMTS13 dependent degradation of VWF to its proteolytic fragments can be visualized as a characteristic so-called triplet structure of individual VWF oligomers by multimer analysis. Lack of VWF high molecular weight multimers (VWF-HMWM) or their pathologically enhanced degradation underlies a particular type of von Willebrand disease, VWD type 2A with a significant bleeding tendency, and may also be observed in acquired von Willebrand syndrome due to cardiovascular disease. In these conditions multimer analysis is an obligatory and powerful tool for diagnosis of VWD. The opposite condition, the persistence of ultralarge VWF (UL-VWF) multimers may cause the microangiopathic life-threatening disorder thrombotic thrombocytopenic purpura (TTP). During the course of active TTP, UL-VWF is consumed in the hyaline thrombi formed in the microvasculature which will ultimately result in the loss of UL-VWF and VWF-HMWM. Therefore, VWF multimer analysis is not a valid tool to diagnose TTP in the active phase of disease but may be helpful for the diagnosis of TTP patients in remission.

  16. [Biology of von Willebrand factor].

    PubMed

    Girma, Jean-Pierre

    2006-01-01

    Von Willebrand factor (VWF) is a multimeric glycoprotein synthesized by megakaryocytes and endothelial cells. It is stored in platelets and endothelial cells and secreted towards subendothelium and plasma. VWF multimers consist of linear arrangements of identical subunits with a molecular weight of 270 kDa. The longest multimers reach more than 20 x 10(6) Da in storage granules. In the circulation, the multimer size is limited by the specific protease ADAMTS13. In primary hemostasis, VWF plays a key role as a molecular bridge in adhesion between platelets and subendothelium and between platelets during their aggregation. These functions, which involve the interaction with platelet glycoprotein lb, are mainly enhanced by VWF immobilization onto hydrophobic surfaces (collagen, cell membrane) and by high shear rates found in microcirculation and stenosed arteries. In these functions, the higher molecular weight forms are the most efficient. Under such hemodynamic conditions, proteolytic activity of ADAMTS13 is also optimal and limits the multimer size to about 15 x 10(6) Da as soon as their secretion. Thus ADAMTS13 appears as a key physiologic regulator of the VWF platelet functions. In the microcirculation, the lack of ADAMTS13 activity can result in the formation of VWF-rich platelet aggregates responsible for thrombotic thrombocytopenic purpura.

  17. The Functions of the A1A2A3 Domains in Von Willebrand Factor Include Multimerin 1 Binding

    PubMed Central

    Parker, D’Andra N.; Tasneem, Subia; Farndale, Richard W.; Bihan, Dominique; Sadler, J. Evan; Sebastian, Silvie; De Groot, Philip G.

    2016-01-01

    Summary Multimerin 1 (MMRN1) is a massive, homopolymeric protein that is stored in platelets and endothelial cells for activation-induced release. In vitro, MMRN1 binds to the outer surfaces of activated platelets and endothelial cells, the extracellular matrix (including collagen) and von Willebrand factor (VWF) to support platelet adhesive functions. VWF associates with MMRN1 at high shear, not static conditions, suggesting that shear exposes cryptic sites within VWF that support MMRN1 binding. Modified ELISA and surface plasmon resonance were used to study the structural features of VWF that support MMRN1 binding, and determine the affinities for VWF-MMRN1 binding. High shear microfluidic platelet adhesion assays determined the functional consequences for VWF-MMRN1 binding. VWF binding to MMRN1 was enhanced by shear exposure and ristocetin, and required VWF A1A2A3 region, specifically the A1 and A3 domains. VWF A1A2A3 bound to MMRN1 with a physiologically relevant binding affinity (KD: 2.0 ± 0.4 nM), whereas the individual VWF A1 (KD: 39.3 ± 7.7 nM) and A3 domains (KD: 229 ± 114 nM) bound to MMRN1 with lower affinities. VWF A1A2A3 was also sufficient to support the adhesion of resting platelets to MMRN1 at high shear, by a mechanism dependent on VWF-GPIbα binding. Our study provides new information on the molecular basis of MMRN1 binding to VWF, and its role in supporting platelet adhesion at high shear. We propose that at sites of vessel injury, MMRN1 that is released following activation of platelets and endothelial cells, binds to VWF A1A2A3 region to support platelet adhesion at arterial shear rates. PMID:27052467

  18. Biosynthesis, processing and secretion of von Willebrand factor: biological implications.

    PubMed

    de Wit, T R; van Mourik, J A

    2001-06-01

    von Willebrand factor is a multimeric plasma glycoprotein that is required for normal haemostasis. von Willebrand factor is synthesized by endothelial cells and megakaryocytes, and originates from its precursor pro-von Willebrand factor. The endoproteolytic processing of pro-von Willebrand factor results in mature von Willebrand factor and von Willebrand factor propeptide (also known as von Willebrand Ag II). In endothelial cells, the propeptide controls the polymerization and subsequent targeting of von Willebrand factor to the storage vesicles, the so-called Weibel-Palade bodies. Upon stimulation of the endothelial cells, the Weibel-Palade bodies are translocated to the plasma membrane of the cell, and mature von Willebrand factor and its propeptide are co-secreted. After release, these polypeptides have divergent fates and serve different biological functions. Mature von Willebrand factor both controls platelet adhesion and aggregation at sites of vascular injury and acts as a chaperone protein for coagulation factor VIII. The von Willebrand factor propeptide may serve a role in modulating inflammatory processes. This still growing body of information indicates that the biological function of the von Willebrand factor gene product is more diverse than was previously thought.

  19. State of the art: von Willebrand disease.

    PubMed

    James, A H; Eikenboom, J; Federici, A B

    2016-07-01

    The State of the Art in von Willebrand disease (VWD) has been impacted not only by discoveries in the field of haemostasis, but also by changes in practice in other fields. The development of bleeding assessment tools has led to the clarification of bleeding symptoms and phenotype in VWD. New discoveries in the biology and genetics of von Willebrand factor (VWF) are challenging our existing diagnostics and classification(s). An improved understanding of reproductive physiology and the pathology of VWD along with changing obstetric, gynaecologic and haemostatic therapies necessitate an evolving response to the care of women with VWD. The survival of patients with autoimmune disease, malignancies and congenital heart disease along with increasing use of circulatory support devices and extracorporeal membrane oxygenation is increasing the prevalence of acquired von Willebrand syndrome. In each of these challenges, there are opportunities to improve the care of our patients with VWD.

  20. Treatment of the acquired von Willebrand syndrome.

    PubMed

    Budde, Ulrich; Scheppenheim, Sonja; Dittmer, Rita

    2015-12-01

    Acquired von Willebrand syndrome (aVWS) accounts for 22% of patients with abnormal von Willebrand factor. Most patients with known pathophysiological mechanisms suffer from cardiovascular, myeloproliferative and lymphoproliferative disorders. Less frequent associations are of autoimmune origin, due to hyperfibrinolysis, adsorption to tumor cells, reduced synthesis and prolonged circulation. The mechanisms leading to aVWS is hitherto not known in patients with liver and kidney diseases, drug use, glycogen storage disease, virus infections and at least 18 other disease entities. Diagnosis is complicated by the battery of tests needed, and their inherent rather low sensitivity and specificity for aVWS. Thus, even in acute bleeding situations it may take days until a firm diagnosis is settled and specific therapies can be initiated. The main aim is to shed more light onto this, compared with inherited von Willebrand disease, rare disease which affects at least 2-3% of the older population.

  1. Sulfation of von Willebrand factor

    SciTech Connect

    Carew, J.A.; Browning, P.J.; Lynch, D.C. )

    1990-12-15

    von Willebrand factor (vWF) is a multimeric adhesive glycoprotein essential for normal hemostasis. We have discovered that cultured human umbilical vein endothelial cells incorporate inorganic sulfate into vWF. Following immunoisolation and analysis by polyacrylamide or agarose gel electrophoresis, metabolically labeled vWF was found to have incorporated (35S)-sulfate into all secreted multimer species. The time course of incorporation shows that sulfation occurs late in the biosynthesis of vWF, near the point at which multimerization occurs. Quantitative analysis suggests the presence, on average, of one molecule of sulfate per mature vWF subunit. Virtually all the detectable sulfate is released from the mature vWF subunit by treatment with endoglycosidases that remove asparagine-linked carbohydrates. Sulfated carbohydrate was localized first to the N-terminal half of the mature subunit (amino acids 1 through 1,365) by partial proteolytic digestion with protease V8; and subsequently to a smaller fragment within this region (amino acids 273 through 511) by sequential digestions with protease V8 and trypsin. Thus, the carbohydrate at asparagine 384 and/or 468 appears to be the site of sulfate modification. Sodium chlorate, an inhibitor of adenosine triphosphate-sulfurylase, blocks sulfation of vWF without affecting either the ability of vWF to assemble into high molecular weight multimers or the ability of vWF multimers to enter Weible-Palade bodies. The stability of vWF multimers in the presence of an endothelial cell monolayer also was unaffected by the sulfation state. Additionally, we have found that the cleaved propeptide of vWF is sulfated on asparagine-linked carbohydrate.

  2. Structural specializations of A2, a force-sensing domain in the ultralarge vascular protein von Willebrand factor

    SciTech Connect

    Zhang, Qing; Zhou, Yan-Feng; Zhang, Cheng-Zhong; Zhang, Xiaohui; Lu, Chafen; Springer, Timothy A.; Harvard-Med

    2009-06-30

    The lengths of von Willebrand factor (VWF) concatamers correlate with hemostatic potency. After secretion in plasma, length is regulated by hydrodynamic shear force-dependent unfolding of the A2 domain, which is then cleaved by a specific protease. The 1.9-{angstrom} crystal structure of the A2 domain demonstrates evolutionary adaptations to this shear sensor function. Unique among VWF A (VWA) domains, A2 contains a loop in place of the {alpha}4 helix, and a cis-proline. The central {beta}4-strand is poorly packed, with multiple side-chain rotamers. The Tyr-Met cleavage site is buried in the {beta}4-strand in the central hydrophobic core, and the Tyr structurally links to the C-terminal {alpha}6-helix. The {alpha}6-helix ends in 2 Cys residues that are linked by an unusual vicinal disulfide bond that is buried in a hydrophobic pocket. These features may narrow the force range over which unfolding occurs and may also slow refolding. Von Willebrand disease mutations, which presumably lower the force at which A2 unfolds, are illuminated by the structure.

  3. [Research advance in von Willebrand factor].

    PubMed

    Li, Xue-Mei; Jiang, Miao; Zhao, Yi-Ming

    2013-06-01

    von Willebrand factor (vWF) is a multimeric glycoprotein exclusively synthesized in endothelial cells and megakaryocytes. It plays important roles in the primary and secondary haemostasis. Deficiency or dysfunction of vWF may cause von Willebrand disease (vWD), and overexpression of vWF may cause thrombosis. Making an intensive study on vWF will help us to understand the pathophysiology, diagnosis and treatment of vWF-related diseases, such as vWD, TTP, venous thrombosis, stroke, and so on. In this article, the regulation of vWF activity and its relation with diseases mentioned above are reviewed.

  4. Laboratory diagnosis of von Willebrand disease.

    PubMed

    Roberts, J C; Flood, V H

    2015-05-01

    Von Willebrand disease (VWD) is considered the most common inherited bleeding disorder and may also be the most difficult to diagnose. Clinical symptoms of VWD include predominantly mild mucosal bleeding; surgical bleeding may occur with specific challenges and joint bleeding can occur in the most severe forms. A family history either of diagnosed VWD or of bleeding symptoms is typically present. Laboratory diagnosis requires a series of assays of von Willebrand factor (VWF) quantity and function, and factor VIII activity, with no single straightforward diagnostic test available to either confirm or exclude the diagnosis. Newer assays of VWF function are becoming more available and useful in determining the laboratory diagnosis of VWD.

  5. Diagnostic Value of Measuring Platelet Von Willebrand Factor in Von Willebrand Disease

    PubMed Central

    Casonato, Alessandra; Cattini, Maria Grazia; Daidone, Viviana; Pontara, Elena; Bertomoro, Antonella; Prandoni, Paolo

    2016-01-01

    Von Willebrand disease (VWD) may be caused by an impaired von Willebrand factor (VWF) synthesis, its increased clearance or abnormal function, or combinations of these factors. It may be difficult to recognize the different contributions of these anomalies. Here we demonstrate that VWD diagnostics gains from measuring platelet VWF, which can reveal a defective VWF synthesis. Measuring platelet VWF revealed that: severe type 1 VWD always coincided with significantly lower platelet and plasma VWF levels, whereas mild forms revealed low plasma VWF levels associated with low or normal platelet VWF levels, and the latter were associated with a slightly shorter VWF survival; type Vicenza (the archetype VWD caused by a reduced VWF survival) featured normal platelet VWF levels despite significantly reduced plasma VWF levels; type 2B patients could have either normal platelet VWF levels associated with abnormal multimer patterns, or reduced platelet VWF levels associated with normal multimer patterns; type 2A patients could have reduced or normal platelet VWF levels, the former associated mainly with type 2A-I, the latter with type 2A-II; plasma and platelet VWF levels were normal in type 2N, except when the defect was associated with a quantitative VWF mutation. Our findings show that measuring platelet VWF helps to characterize VWD, especially the ambiguous phenotypes, shedding light on the mechanisms underlying the disorder. PMID:27532107

  6. [Molecular biology of von Willebrand disease].

    PubMed

    Melo-Nava, Brenda; Peñaloza, Rosenda

    2007-01-01

    Von Willebrand Factor (VWF) is a large multimeric glycoprotein expressed in the megakaryocytes and endothelial cells of all vertebrates. It participates fundamentally in the primary and secondary hemostasis because it induces the adhesion of platelets to vascular subendothelium and promotes aggregation of platelets when blood vessels and capillaries are damaged. In addition, VWF links to factor VIII which avoids its proteolysis. The deficiency or the inadequate synthesis of the VWF causes von Willebrand disease (VWD), which is the most common hereditary bleeding disorder in humans principally from mucous and cutaneous sites. VWD is difficult to detect with accuracy due to interrelation among VWF with different components of hemostasis, although it is performed by different tests of haemostatic system, and the basic mechanisms in VWD are herein emphasized. The diagnosis of VWD is difficult due to the heterogeneous manifestation of the disease, which also complicates its classification. This article focuses on the molecular aspects of the disease and discusses their possible clinical implications.

  7. Marshall-Stickler phenotype associated with von Willebrand disease

    SciTech Connect

    MacDonald, M.R.; Baker, K.S.; Schaefer, G.B.

    1997-01-20

    We report on 6 individuals from three different kindreds with Marshall-Stickler (MS) phenotype, with characteristic orofacial abnormalities, arthropathy, deafness, and eye findings, all of whom were discovered to have a mild bleeding diathesis and coagulation-study findings consistent with mild von Willebrand disease (vWD). MS syndrome has been linked in some cases to the type II procollagen gene (COL2A1) on chromosome 12q, and to the collagen XI gene (COL11A2) on chromosome 6. The von Willebrand factor (vWF) is encoded by a 180-Kb gene located on the short arm of chromosome 12. This is the first reported association of these two disorders. 26 refs., 5 figs., 1 tab.

  8. Acquired von Willebrand syndrome: von Willebrand factor propeptide to von Willebrand factor antigen ratio predicts remission status

    PubMed Central

    Lee, Adrienne; Sinclair, Gary; Valentine, Karen; James, Paula

    2014-01-01

    We investigated a case of acquired von Willebrand syndrome (AVWS) secondary to a nonneutralizing anti-von Willebrand factor (VWF) antibody associated with an autoimmune disorder. At diagnosis, VWF activity (VWF:Act), antigen (VWF:Ag), multimers, and factor VIII coagulant activity were virtually absent. VWF propeptide (VWFpp) was elevated with an infinitely high VWFpp to VWF:Ag ratio (VWFpp:Ag) consistent with rapid VWF clearance. Immunosuppressive treatment resulted in phenotypic remission 1 with normalization of VWF/factor VIII levels and multimer pattern. However, VWFpp:Ag remained elevated (∼2× normal), consistent with ongoing VWF clearance by the remaining anti-VWF antibody still present by enzyme-linked immunosorbent assay. This suggests that increased VWF secretion was compensating for the incomplete remission state. Relapse occurred when VWFpp:Ag was again infinitely high, with associated decreased VWFpp but unchanged anti-VWF titers; switching the balance to favor VWF clearance over secretion. Complete remission with undetectable anti-VWF occurred only when VWFpp:Ag was normal. This case of relapsing-remitting AVWS demonstrates the use of VWFpp:Ag for predicting remission status. PMID:24951428

  9. Report on von Willebrand Disease in Malaysia

    PubMed Central

    Periayah, Mercy Halleluyah; Halim, Ahmad Sukari; Saad, Arman Zaharil Mat; Yaacob, Nik Soriani; Karim, Faraizah Abdul

    2016-01-01

    BACKGROUND: Von Willebrand disease (vWD) is an inherited hemostatic disorder that affects the hemostasis pathway. The worldwide prevalence of vWD is estimated to be 1% of the general population but only 0.002% in Malaysia. AIM: Our present paper has been written to disclose the statistical counts on the number of vWD cases reported from 2011 to 2013. MATERIAL AND METHODS: This article is based on sociodemographic data, diagnoses and laboratory findings of vWD in Malaysia. A total of 92 patients were reported to have vWD in Malaysia from 2011 to 2013. RESULTS: Sociodemographic-analysis revealed that 60% were females, 63% were of the Malay ethnicity, 41.3% were in the 19-44 year old age group and 15.2% were from Sabah, with the East region having the highest registered number of vWD cases. In Malaysia, most patients are predominately affected by vWD type 1 (77.2%). Factor 8, von Willebrand factor: Antigen and vWF: Collagen-Binding was the strongest determinants in the laboratory profiles of vWD. CONCLUSION: This report has been done with great interest to provide an immense contribution from Malaysia, by revealing the statistical counts on vWD from 2011-2013. PMID:27275342

  10. Molecular diagnosis of von Willebrand disease.

    PubMed

    Baronciani, L; Goodeve, A; Peyvandi, F

    2017-03-01

    The role of molecular characterization in the diagnosis of von Willebrand disease (VWD) is not essential if the patients have been extensively investigated using phenotypic analysis. On the other hand, if some of these phenotype assays are not available, the identification of the mutation causing the disease could be crucial for an accurate diagnosis. Nevertheless, there are several reasons for performing molecular analysis in patients phenotypically well characterized, e.g. to identify the mutation causing VWD can be useful for patients and their family members when prenatal diagnosis is required (type 3 or severe type 2). In this manuscript, we report the techniques used for the molecular characterization of suspected VWD patients. We describe the use of online von Willebrand factor database and online single nucleotide variation databases, the former to verify whether a candidate mutation has been previously identified in other VWD patients and the latter to ascertain whether a putative mutation has been reported earlier in healthy individuals. We listed the available in silico analysis tools, to determine the predicted pathogenicity of a sequence variant and to establish its possible negative effect on the normal splicing process. We also report the strategy that can be used to identify VWD type 2 patients' mutations in subjects who have been fully characterized using the phenotype assays.

  11. [Von Willebrand disease in the Netherlands: the WiN study].

    PubMed

    Sanders, Yvonne V; de Wee, Eva M; Meijer, Karina; Eikenboom, J; van der Bom, Jeroen G; Fijnvandraat, C J Karin; Laros-van Gorkom, Britta A P; Cnossen, Marjon H; Mauser-Bunschoten, Evelien P; Leebeek, Frank W G

    2014-01-01

    Von Willebrand disease is the most common inherited bleeding disorder and is characterised by mucocutaneous bleeding. Von Willebrand disease is caused by reduced levels or reduced function of von Willebrand factor. Depending on the cause, von Willebrand disease is distinguished into various types with their own characteristics and treatment options. The frequency and severity of bleeding in patients with von Willebrand disease is strongly determined by von Willebrand factor levels, factor VIII levels and the type of von Willebrand disease. Eighty-five percent of all adult females with von Willebrand disease reports menorrhagia. A high percentage have postpartum excessive blood loss (37% of all deliveries). The quality of life is reduced in patients with von Willebrand disease. Patients with von Willebrand disease have a reduced risk of arterial thrombosis such as a myocardial or cerebral infarction.

  12. Two novel anti-von Willebrand factor monoclonal antibodies.

    PubMed

    Spadafora-Ferreira, M; Lopes, A A; Coelho, V; Guilherme, L; Kalil, J

    2000-01-15

    Von Willebrand Factor is a multimer produced by endothelial cells and megakaryocytes, being stored in intracellular organelles, such as the Weibel-Palade bodies and alpha-granules in endothelial cells and platelets, respectively. This molecule acts as a carrier protein for factor VIIIc, involved in the intrinsic pathway of blood coagulation maintaining its stability in circulation. Von Willebrand Factor also plays an important role in platelet aggregation and adhesion to injured vessel wall. It interacts with platelets through two distinct glycoproteins, GPIb and GPIIb/IIIa. We raised two monoclonal antibodies, ECA-3 and ECA-4, against human umbilical vascular endothelial cells that recognize and immunoprecipitate von Willebrand Factor. Interestingly, ECA-4 monoclonal antibody is able to completely inhibit platelet agglutination induced by ristocetin, suggesting that it binds to von Willebrand Factor close to platelet GPIb binding site. The use of monoclonal antibodies to identify von Willebrand Factor binding regions to factor VIII or platelets has been reported by others. In pulmonary hypertension, abnormalities have been detected on the multimeric structure of the molecule as well as on its proteolytic fragments, by using monoclonal antibodies. Moreover, monoclonal antibodies raised against specific regions of von Willebrand Factor molecule may allow studies of functional abnormalities of this protein in inherited and acquired disorders like subtypes of von Willebrand's disease.

  13. Gastrointestinal angiodysplasia and bleeding in von Willebrand disease.

    PubMed

    Franchini, M; Mannucci, P M

    2014-09-02

    Von Willebrand disease (VWD), the most common genetic bleeding disorder, is characterised by a quantitative or qualitative defect of von Willebrand factor (VWF). Patients with VWD suffer from mucocutaneous bleeding, of severity usually proportional to the degree of VWF defect. In particular, gastrointestinal bleeding associated with angiodysplasia is often a severe symptom of difficult management. This review focuses on the pathophysiology, diagnosis and treatment of VWD-associated gastrointestinal angiodysplasia and related bleeding.

  14. Management of Type 2B von Willebrand Disease during Pregnancy.

    PubMed

    McLaughlin, David; Kerr, Ron

    2017-01-01

    Type 2B von Willebrand disease is a rare bleeding condition resulting in thrombocytopenia and a reduction in large VWF multimers. It usually has an autosomal dominant pattern of inheritance. We report the management of a patient with type 2B von Willebrand disease, whose diagnosis was confirmed by demonstration of a R1306W mutation, through her first pregnancy. The patient's von Willebrand factor (VWF) antigen and VWF ristocetin cofactor levels rose throughout pregnancy, with an associated drop in the platelet count. The patient was successfully managed through labour to a surgical delivery with VWF concentrate, platelet transfusions and tranexamic acid. The patient delivered a male baby who was found to have inherited type 2B von Willebrand disease and had a significant cephalhaematoma at delivery. The baby was managed with VWF concentrate and platelet transfusions and made a full recovery. There is a lack of evidence to guide the best management of pregnant patients with type 2B von Willebrand disease. We adopted a pragmatic management plan, in keeping with other published case reports. To the best of our knowledge, this is the first case report in which the child was found to have inherited type 2B von Willebrand disease and encountered bleeding problems, making this case unique amongst the published literature.

  15. von Willebrand factor expression in osteosarcoma metastasis.

    PubMed

    Eppert, Kolja; Wunder, Jay S; Aneliunas, Vicky; Kandel, Rita; Andrulis, Irene L

    2005-03-01

    A number of genes are implicated in the initiation and progression of osteosarcoma; however, cytogenetic and comparative genomic hybridization studies indicate the involvement of additional unidentified genes. An examination of gene expression profiles in 22 high-grade osteosarcoma tumor specimens from 15 patients (including paired primary and metastatic samples from five patients) indicated that von Willebrand factor (vWF) mRNA expression may increase during tumor progression. vWF, a large glycoprotein previously considered to be expressed exclusively by endothelial cells and megakaryocytes, is involved in platelet aggregation and adhesion to the subendothelial matrix, processes critical to hematogenous tumor cell metastasis to the lung. Analysis of paired primary and metastatic osteosarcoma tumor samples from 10 patients revealed an increase in vWF gene expression in metastases (P=0.005). Immunohistochemistry showed that, in addition to the endothelial cells, vWF protein was also detected in osteosarcoma cells in vivo in 13 of 29 tumor specimens as well as in SAOS2, an osteosarcoma cell line. The tumor cell staining correlated positively with high vWF expression in the sample (P=0.006). Although vascular endothelial cells contribute to the vWF mRNA detected in the tumor samples, there was neither any correlation between vascular density (VD) and vWF mRNA expression nor between VD and clinical outcome. These findings suggest that vWF expression is deregulated in osteosarcoma tumors, potentially contributing to metastasis.

  16. Unwinding the von Willebrand factor strings puzzle.

    PubMed

    De Ceunynck, Karen; De Meyer, Simon F; Vanhoorelbeke, Karen

    2013-01-10

    von Willebrand factor (VWF) is amongst others synthesized by endothelial cells and stored as ultra-large (UL) VWF multimers in Weibel-Palade bodies. Although UL-VWF is proteolysed by ADAMTS13 (a disintegrin-like and metalloprotease domain with thrombospondin type-1 motif, number 13) on secretion from endothelial cells, in vitro experiments in the absence of ADAMTS13 have demonstrated that a proportion of these UL-VWF multimers remain anchored to the activated endothelium. These multimers unravel, bind platelets, and wave in the direction of the flow. These so-called VWF "strings" have also been visualized in vivo, lining the lumen of activated mesenteric veins of Adamts13(-/-) mice. Various studies have demonstrated the extraordinary length of these VWF strings, the availability of their platelet binding and ADAMTS13 cleavage sites, and the possible nature of their endothelial attachment. VWF strings are also capable of tethering leukocytes and parasite-infected red blood cells. However, the majority of studies have been performed in the absence of ADAMTS13, a condition only experienced in thrombotic thrombocytopenic purpura. A normal functional role of VWF strings in healthy persons or in other disease pathologies remains unclear. In this review, we discuss some of the puzzling characteristics of VWF strings, and we debate whether the properties of VWF strings in the absence of ADAMTS13 might be relevant for understanding (patho)physiologic mechanisms.

  17. Exponential Size Distribution of von Willebrand Factor

    PubMed Central

    Lippok, Svenja; Obser, Tobias; Müller, Jochen P.; Stierle, Valentin K.; Benoit, Martin; Budde, Ulrich; Schneppenheim, Reinhard; Rädler, Joachim O.

    2013-01-01

    Von Willebrand Factor (VWF) is a multimeric protein crucial for hemostasis. Under shear flow, it acts as a mechanosensor responding with a size-dependent globule-stretch transition to increasing shear rates. Here, we quantify for the first time, to our knowledge, the size distribution of recombinant VWF and VWF-eGFP using a multilateral approach that involves quantitative gel analysis, fluorescence correlation spectroscopy, and total internal reflection fluorescence microscopy. We find an exponentially decaying size distribution of multimers for recombinant VWF as well as for VWF derived from blood samples in accordance with the notion of a step-growth polymerization process during VWF biosynthesis. The distribution is solely described by the extent of polymerization, which was found to be reduced in the case of the pathologically relevant mutant VWF-IIC. The VWF-specific protease ADAMTS13 systematically shifts the VWF size distribution toward smaller sizes. This dynamic evolution is monitored using fluorescence correlation spectroscopy and compared to a computer simulation of a random cleavage process relating ADAMTS13 concentration to the degree of VWF breakdown. Quantitative assessment of VWF size distribution in terms of an exponential might prove to be useful both as a valuable biophysical characterization and as a possible disease indicator for clinical applications. PMID:24010664

  18. Recombinant von Willebrand factor: a first-of-its-kind product for von Willebrand disease.

    PubMed

    Singal, M; Kouides, P A

    2016-12-01

    von Willebrand disease (VWD) is caused by quantitative or qualitative defects in von Willebrand factor (VWF). The mainstay of therapy is desmopressin, which is, however, not useful in certain forms of VWD notwithstanding adverse events. For these patients, plasma-derived factor VIII (pdFVIII)/VWF concentrates have been available for close to three decades but have a theoretical risk of disease transmission, hypersensitivity/allergic reactions, inhibitors and thrombosis. A recombinant VWF (vonicog alfa, Vonvendi™; manufactured by Baxalta, now part of Shire) was approved by the U.S. Food and Drug Administration (FDA) in December 2015. This review will survey the literature based on a MEDLINE review on the safety, efficacy and pharmacokinetics of Vonvendi. It will also summarize the ongoing studies on Vonvendi available in the public domain. Vonvendi may have an important role in the management of VWD. However, more studies are needed, especially in special populations such as surgical patients, patients with major gastrointestinal bleeding from arteriovenous malformations and pregnant women and children, who are most likely to benefit from it.

  19. Developments in the diagnostic procedures for von Willebrand disease.

    PubMed

    De Jong, A; Eikenboom, J

    2016-03-01

    Von Willebrand disease (VWD) is the most common inherited bleeding disorder but its diagnosis can be challenging due to the heterogeneity of the disease. VWD is mainly associated with mild mucocutaneous bleeding, although there are more severe phenotypes with bleeding from the gastrointestinal tract or even the joints. Also, surgical interventions and trauma may lead to critical bleeding events. These bleeding episodes are all related to quantitative or qualitative defects of von Willebrand factor (VWF), a multimeric glycoprotein produced by endothelial cells and megakaryocytes, which mediates platelet adhesion and aggregation and binds factor VIII (FVIII) in the circulation. This review describes the diagnostic procedures required for correct diagnosis. Accurate diagnosis and classification is required for proper treatment and counseling. Assessment of bleeding starts with the medical history. After a positive bleeding or family history, subsequent laboratory investigations will start with a panel of standard screening tests for hemostatic defects. Patients suspected of having VWD will be tested for plasma VWF antigen levels, the ability of VWF to bind platelets and FVIII activity. When VWD is confirmed, a set of subtyping tests can classify the patients as VWD types 1, 2 (A, B, M or N) or 3. The performance of some additional assays and analyses, such as VWF propeptide measurement or genetic analysis, may help in identifying the pathological mechanism behind certain defects or can guide in the choice of treatment.

  20. Biosynthesis of von Willebrand protein by human megakaryocytes.

    PubMed

    Sporn, L A; Chavin, S I; Marder, V J; Wagner, D D

    1985-09-01

    Immunofluorescence staining of buffy coat smears from a patient with chronic myelogenous leukemia in accelerated phase showed that approximately 13% of all nucleated cells contained von Willebrand protein and, therefore, appeared to be of megakaryocytic origin. This was confirmed by positive staining with antisera against platelet factor 4 and platelet glycoproteins. Short-term cultures of the buffy coat, which lacked endothelial cells, were metabolically labeled with [35S]methionine, and von Willebrand protein was immunopurified from cell lysates and culture medium. Cultures from this patient synthesized and secreted von Willebrand protein, in contrast with cultures from other patients with leukemia, who lacked circulating megakaryocytes, and from normal volunteers. The subunit composition of the megakaryocytic von Willebrand protein was very similar to that of human umbilical vein endothelial cells. The size of the processed subunit (220 kD) and of the cellular (260 kD) and secreted (275 kD) precursors from the two cell types were indistinguishable by gel electrophoresis. Furthermore, the ratio of precursor to processed subunit and the pattern of cellular and secreted nonreduced multimers were very similar. It appears, therefore, that the processing steps in biosynthesis of von Willebrand protein used by the megakaryocytes are very similar to those of umbilical vein endothelial cells.

  1. Committee Opinion No.580: von Willebrand disease in women.

    PubMed

    2013-12-01

    Von Willebrand disease, the most common inherited bleeding disorder among American women, is a common cause of heavy menstrual bleeding and other bleeding problems in women and adolescent girls. Von Willebrand disease and other inherited and acquired disorders of coagulation and hemostasis should be considered in the differential diagnosis of all patients being evaluated for heavy menstrual bleeding, regardless of age. There are many treatment options available for patients with von Willebrand disease and heavy menstrual bleeding, including hormonal and nonhormonal therapies. A multidisciplinary approach to management, which involves obstetrician-gynecologists and hematologists, results in optimal treatment outcomes. Many resources exist for patients and health care providers through the National Heart, Lung, and Blood Institute; National Hemophilia Foundation; and the American Society of Hematology.

  2. Thrombospondin-1 in von Willebrand factor function.

    PubMed

    Bonnefoy, Arnaud; Hoylaerts, Marc F

    2008-10-01

    Thrombospondin-1 (TSP1), expressed in many cells and tissues is abundantly present in platelet alpha-granules, from where it is released upon platelet activation. Murine Tsp1(-/-) platelet studies have revealed that TSP1 is redundant for platelet aggregation, but that it reinforces platelet aggregate stabilization, especially in a shear field. von Willebrand factor (VWF), synthesized by megakaryocytes and endothelial cells is stored both in platelet alpha-granules and in endothelial Weibel-Palade bodies as ultralarge multimers. When released from endothelial cells, these multimers are temporarily retained on the endothelium, to be cleaved by the plasma protease ADAMTS13 into smaller and hemostatically less reactive multimers, released in plasma. This protease shows partial sequence identity with the type 1 (TSR1) and type 2 (TSR2) repeats of TSP1 and contains 1 TSR1 and 6 TSR2 repeats. TSP1, locally released by platelets, competes with ADAMTS13 during VWF proteolysis and controls the degree of VWF multimer processing. In addition, TSP1 and VWF both interact with the platelet GPIb/V/IX membrane complex, primarily in flow. These interactions control the recruitment of platelets to (sub) endothelial VWF and TSP1, exposed to the circulation, as a consequence of vascular inflammation and endothelial injury. TSP1-VWF interactions do not strictly enhance platelet recruitment and secreted TSP1 even weakly competes with the dynamic platelet rolling and adhesion onto VWF. Hence, TSP1 and VWF show partially related hemostatic functions, the most important one being the TSP1 role in the ADAMTS13 operated VWF multimer processing, in pro-inflammatory and thrombogenic conditions.

  3. Endothelial dysfunction in von Willebrand disease: angiogenesis and angiodysplasia.

    PubMed

    Randi, Anna M

    2016-05-01

    In recent years, new functions for the haemostatic protein von Willebrand Factor (VWF) have emerged. Amongst these is the ability to modulate the development of new blood vessels, a process called angiogenesis. The subtle effects that VWF exerts on blood vessel formation and stability may be relevant for the small but significant fraction of patients with von Willebrand disease (VWD) who also present with vascular malformations (angiodysplasia) in the gastrointestinal tract, often responsible for intractable bleeding. This review will briefly summarise the evidence and discuss the molecular pathways involved.

  4. Weibel-Palade bodies: a window to von Willebrand disease.

    PubMed

    Valentijn, K M; Eikenboom, J

    2013-04-01

    Weibel-Palade bodies (WPBs) are the storage organelles for von Willebrand factor (VWF) in endothelial cells. VWF forms multimers that assemble into tubular structures in WPBs. Upon demand, VWF is secreted into the blood circulation, where it unfolds into strings that capture platelets during the onset of primary hemostasis. Numerous mutations affecting VWF lead to the bleeding disorder von Willebrand disease. This review reports the recent findings on the effects of VWF mutations on the biosynthetic pathway of VWF and its storage in WPBs. These new findings have deepened our understanding of VWF synthesis, storage, secretion, and function.

  5. Current therapy in children and adolescents with von Willebrand disease.

    PubMed

    Buga-Corbu, I; Arion, C

    2014-06-15

    The article represents a review of recent data about the therapy of von Willebrand disease in children and adolescents (hereditary as well as acquired forms of the disease). The treatment of bleeding events in these patients, the indications in different subtypes, and the future lines of research are mentioned.

  6. Expression of abnormal von Willebrand factor by endothelial cells from a patient with type IIA von Willebrand disease.

    PubMed Central

    Levene, R B; Booyse, F M; Chediak, J; Zimmerman, T S; Livingston, D M; Lynch, D C

    1987-01-01

    Studies were conducted to characterize the biosynthesis of von Willebrand factor (vWf) by cultured endothelial cells (EC) derived from the umbilical vein of a patient with type IIA von Willebrand disease. The patient's EC, compared with those from normal individuals, produced vWf that had decreased amounts of large multimers and an increase in rapidly migrating satellite species, features characteristic of plasma vWf from patients with type IIA von Willebrand disease. The type IIA EC did produce a full spectrum of vWf multimers in both cell lysates and postculture medium, although the relative amounts of the largest species were decreased. The large multimers were degraded in conjunction with the appearance of rapidly migrating satellites that contained approximately equal to 170-kDa proteolytic fragments, suggesting that this patient's functional defect is due to abnormal proteolysis and not to a primary failure of vWf subunit oligomerization. Moreover, the observed degradation appears to result from an abnormal vWf molecule and not elevated protease levels. These results suggest that this patient's von Willebrand disease phenotype is caused by increased proteolytic sensitivity of his vWf protein. Images PMID:3306682

  7. Diagnostic Differentiation of von Willebrand Disease Types 1 and 2 by von Willebrand Factor Multimer Analysis and DDAVP Challenge Test.

    PubMed

    Michiels, Jan Jacques; Smejkal, Petr; Penka, Miroslav; Batorova, Angelika; Pricangova, Tatiana; Budde, Ulrich; Vangenechten, Inge; Gadisseur, Alain

    2016-01-01

    The European Clinical Laboratory and Molecular (ECLM) classification of von Willebrand disease (vWD) is based on the splitting approach which uses sensitive and specific von Willebrand factor (vWF) assays with regard to the updated molecular data on structure and function of vWF gene and protein defects. A complete set of FVIII:C and vWF ristocetine cofactor, collagen binding, and antigen, vWF multimeric analysis in low- and medium-resolution gels, and responses to desmopressin (DDAVP) of FVIII:C and vWF parameters are mandatory. The ECLM classification distinguishes recessive types 1 and 3 vWD from recessive vWD 2C due to mutations in the D1 and D2 domains and vWD 2N due to mutations in the D'-FVIII-binding domain of vWF. The ECLM classification differentiates between mild vWD type 1 with variable penetrance of bleedings from symptomatic dominant type 1 vWD secretion defect and/or clearance defect with normal vWF multimers versus vWD 1M and 2M with normal or smeary vWF multimers in low- and medium-resolution gels. High-quality multimeric analysis of vWF in medium-resolution gels based on a DDAVP challenge test clearly delineates and distinguishes each of the dominant type 2 vWDs 1/2E, 2M, 2B, 2A, and 2D caused by vWF gene mutations in the D3 multimerization domain, loss or gain-of-function mutations in the glycoprotein Ib receptor A1 domain, gene mutations in the A2 proteolytic domain, and the C-terminal dimerization domain, respectively.

  8. Hemostatic efficacy, safety, and pharmacokinetics of a recombinant von Willebrand factor in severe von Willebrand disease

    PubMed Central

    Gill, Joan C.; Castaman, Giancarlo; Windyga, Jerzy; Kouides, Peter; Ragni, Margaret; Leebeek, Frank W. G.; Obermann-Slupetzky, Ortrun; Chapman, Miranda; Fritsch, Sandor; Pavlova, Borislava G.; Presch, Isabella

    2015-01-01

    This phase 3 trial evaluated the safety and hemostatic efficacy of a recombinant von Willebrand factor (rVWF) for treatment of bleeds in severe von Willebrand disease (VWD). rVWF was initially administered together with recombinant factor VIII (rFVIII) and subsequently alone, as long as hemostatic factor VIII activity (FVIII:C) levels were maintained. Pharmacokinetics (PK) were evaluated in a randomized cross-over design (rVWF vs rVWF:rFVIII at 50 IU VWF:ristocetin cofactor activity [RCo]/kg). Bleed control for all treated bleeds (N = 192 bleeds in 22 subjects) was rated good or excellent (96.9% excellent; 119 of 122 minor, 59 of 61 moderate, and 6 of 7 major bleeds) on a 4-point scale (4 = none to 1 = excellent). A single infusion was effective in 81.8% of bleeds. Treatment success, defined as the number of subjects with a mean efficacy rating of <2.5, was 100%. The PK profile of rVWF was not influenced by rFVIII (mean VWF:RCo terminal half-life: 21.9 hours for rVWF and 19.6 hours for rVWF:rFVIII). FVIII:C levels increased rapidly after rVWF alone, with hemostatic levels achieved within 6 hours and sustained through 72 hours after infusion. Eight adverse events (AEs; 6 nonserious AEs in 4 subjects and 2 serious AEs [chest discomfort and increased heart rate, without cardiac symptomatology] concurrently in 1 subject) were associated with rVWF. There were no thrombotic events or severe allergic reactions. No VWF or FVIII inhibitors, anti-VWF binding antibodies, or antibodies against host cell proteins were detected. These results show that rVWF was safe and effective in treating bleeds in VWD patients and stabilizes endogenous FVIII:C, which may eliminate the need for rFVIII after the first infusion. This trial was registered at www.clinicaltrials.gov as #NCT01410227. PMID:26239086

  9. Hemostatic efficacy, safety, and pharmacokinetics of a recombinant von Willebrand factor in severe von Willebrand disease.

    PubMed

    Gill, Joan C; Castaman, Giancarlo; Windyga, Jerzy; Kouides, Peter; Ragni, Margaret; Leebeek, Frank W G; Obermann-Slupetzky, Ortrun; Chapman, Miranda; Fritsch, Sandor; Pavlova, Borislava G; Presch, Isabella; Ewenstein, Bruce

    2015-10-22

    This phase 3 trial evaluated the safety and hemostatic efficacy of a recombinant von Willebrand factor (rVWF) for treatment of bleeds in severe von Willebrand disease (VWD). rVWF was initially administered together with recombinant factor VIII (rFVIII) and subsequently alone, as long as hemostatic factor VIII activity (FVIII : C) levels were maintained. Pharmacokinetics (PK) were evaluated in a randomized cross-over design (rVWF vs rVWF:rFVIII at 50 IU VWF:ristocetin cofactor activity [RCo]/kg). Bleed control for all treated bleeds (N = 192 bleeds in 22 subjects) was rated good or excellent (96.9% excellent; 119 of 122 minor, 59 of 61 moderate, and 6 of 7 major bleeds) on a 4-point scale (4 = none to 1 = excellent). A single infusion was effective in 81.8% of bleeds. Treatment success, defined as the number of subjects with a mean efficacy rating of <2.5, was 100%. The PK profile of rVWF was not influenced by rFVIII (mean VWF:RCo terminal half-life: 21.9 hours for rVWF and 19.6 hours for rVWF:rFVIII). FVIII : C levels increased rapidly after rVWF alone, with hemostatic levels achieved within 6 hours and sustained through 72 hours after infusion. Eight adverse events (AEs; 6 nonserious AEs in 4 subjects and 2 serious AEs [chest discomfort and increased heart rate, without cardiac symptomatology] concurrently in 1 subject) were associated with rVWF. There were no thrombotic events or severe allergic reactions. No VWF or FVIII inhibitors, anti-VWF binding antibodies, or antibodies against host cell proteins were detected. These results show that rVWF was safe and effective in treating bleeds in VWD patients and stabilizes endogenous FVIII : C, which may eliminate the need for rFVIII after the first infusion. This trial was registered at www.clinicaltrials.gov as #NCT01410227.

  10. Principles of care for the diagnosis and treatment of von Willebrand disease.

    PubMed

    Castaman, Giancarlo; Goodeve, Anne; Eikenboom, Jeroen

    2013-05-01

    Von Willebrand disease is a common autosomal inherited bleeding disorder caused by quantitative or qualitative defects of von Willebrand factor, a multi-adhesive protein that binds platelets to exposed subendothelium and carries factor VIII in circulation. As a result of von Willebrand factor deficiency or abnormality, levels of factor VIII, the protein deficient in hemophilia A, may be variably reduced. Clinical manifestations are mainly represented by mucous membrane and of soft tissue bleeding. Their severity is variable depending on the degree of von Willebrand factor and factor VIII reduction. While a clear-cut diagnosis is easy in severe von Willebrand factor reductions, the advantage of pursuing a definite diagnosis in mild or dubious cases should be weighed against the risk of over-medicalization. The aim of treatment is to correct the dual defect of hemostasis caused by the abnormal/reduced von Willebrand factor and the concomitant deficiency of factor VIII. Desmopressin is the treatment of choice for type 1 von Willebrand disease patients with factor VIII and von Willebrand factor levels of 10 U/dL or over who have proved responsive to a test-infusion with the compound. Von Willebrand factor/factor VIII concentrates are needed when desmopressin is ineffective (mainly type 2 and 3 von Willebrand disease).

  11. Structure of von Willebrand factor and its function in platelet adhesion and thrombus formation.

    PubMed

    Ruggeri, Z M

    2001-06-01

    The adhesive protein von Willebrand factor mediates the initiation and progression of thrombus formation at sites of vascular injury. von Willebrand factor is synthesized in endothelial cells and megakaryocytes as a very large polymer composed of identical subunits. In the plasma, it appears as a series of multimers of regularly decreasing molecular mass, from several thousand to 500 kDa. The size of circulating von Willebrand factor multimers is controlled by proteolytic cleavage carried out by a specific protease. The biological functions of von Willebrand factor are exerted through specific domains that interact with extracellular matrix components and cell membrane receptors to promote the initial tethering and adhesion of platelets to subendothelial surfaces, as well as platelet aggregation. Moreover, von Willebrand factor binds the procoagulant co-enzyme, factor VIII, contributing to its stability and, indirectly, to its function in the generation of fibrin. This chapter presents a review of current knowledge on the structure, biosynthesis and functions of von Willebrand factor.

  12. Altered megakaryocytopoiesis in von Willebrand type 2B disease.

    PubMed

    Nurden, A T; Federici, A B; Nurden, P

    2009-07-01

    Type 2B von Willebrand disease (VWD2B) is caused by gain-of-function amino acid substitutions in the von Willebrand factor (VWF) A1 domain. These allow facilitated binding of mutated VWF to platelet GPIbalpha with prolonged lifetimes of VWF bonds and enhanced ADAMTS-13 cleavage of large VWF multimers. A bleeding rather than prothrombotic syndrome is due to: (i) decreased large VWF multimers in plasma; (ii) limited thrombus formation; and (iii) thrombocytopenia affecting some but not all patients. Accumulating evidence points to an altered megakaryocytopoiesis in VWD2B with the production of enlarged or giant platelets showing an abnormal ultrastructure and, in a cohort of patients, the presence of circulating platelet agglutinates. In fact, evidence from in vitro cultures and marrow aspirates suggests that the upregulated VWF function can lead to abnormal VWF trafficking in megakaryocytes, a modified platelet production with interacting proplatelets, and the presence or even release of platelet agglutinates in the bone marrow.

  13. The molecular characterization of von Willebrand disease: good in parts.

    PubMed

    James, P D; Lillicrap, D

    2013-04-01

    Since the cloning of the gene that encodes von Willebrand factor (VWF), 27 years ago, significant progress has been made in our understanding of the molecular basis of the most common inherited bleeding disorder, von Willebrand disease (VWD). The molecular pathology of this condition represents a range of genetic mechanisms, some of which are now very well characterized, and others that are still under investigation. In general, our knowledge of the molecular basis of type 2 and 3 VWD is now well advanced, and in some instances this information is being used to enhance clinical management. In contrast, our understanding of the molecular pathogenesis of the most common form of VWD, type 1 disease, is still at an early stage, with preliminary evidence that this phenotype involves a complex interplay between environmental factors and the influence of genetic variability both within and outside of the VWF locus.

  14. An update on type 2B von Willebrand disease.

    PubMed

    Mikhail, Sameh; Aldin, Ehab Saad; Streiff, Michael; Zeidan, Amer

    2014-04-01

    Type 2B von Willebrand disease (VWD) accounts for fewer than 5% of all VWD patients. In this disease, mutations in the A1 domain result in increased von Willebrand factor (VWF) binding to platelet GPIbα receptors, causing increased platelet clearance and preferential loss of high molecular weight VWF multimers. Diagnosis is complicated because of significant clinical variations even among patients with identical mutations. Platelet transfusion often provides suboptimal results since transfused platelets may be aggregated by the patients' abnormal VWF. Desmopressin may cause a transient decrease in platelet count that could lead to an increased risk of bleeding. Replacement therapy with factor VIII/VWF concentrates is the most effective approach to prevention and treatment of bleeding in type 2B VWD.

  15. Screening of Von Willebrand Disease in Iranian Women With Menorrhagia

    PubMed Central

    Rahbar, Nahid; Faranoush, Mohammad; Ghorbani, Raheb; Sadr Alsadat, Bahare

    2015-01-01

    Background: Menorrhagia is a common health problem in women, particularly those with bleeding disorders. Little is known about the course of menorrhagia or other bleeding symptoms in women with the most common congenital bleeding disorder, von Willebrand disease (vWD). Objectives: The aim of this study was to estimate the prevalence of vWD in women with diagnosed menorrhagia. Materials and Methods: In this cross-sectional study, a total of 460 consecutive patients, presenting menorrhagia, were analyzed. The initial screening and confirmation tests for the diagnosis of vWD included determination of prothrombin time (PT), partial thromboplastin time (PTT), bleeding time (BT), fibrinogen, factor VIII, vWF antigen, and vWF activity. A questionnaire was filled for every patient. The data were then analyzed using the SPSS software. Results: Mean age of our patients was 32.5 ± 10.6 years. The level of von Willebrand factor in 22.5% and von Willebrand activity in 19.6% of patients was abnormal. The prevalence of vWD among patients with menorrhagia was 24%. Conclusions: The high prevalence of vWD among our patients was the same as other previous reports, suggesting low awareness about this disease and under diagnosis of mild cases. PMID:25763275

  16. Clumping factor A, von Willebrand factor-binding protein and von Willebrand factor anchor Staphylococcus aureus to the vessel wall.

    PubMed

    Claes, J; Liesenborghs, L; Peetermans, M; Veloso, T R; Missiakas, D; Schneewind, O; Mancini, S; Entenza, J M; Hoylaerts, M F; Heying, R; Verhamme, P; Vanassche, T

    2017-02-09

    Essentials Staphylococcus aureus (S. aureus) binds to endothelium via von Willebrand factor (VWF). Secreted VWF-binding protein (vWbp) mediates S. aureus adhesion to VWF under shear stress. vWbp interacts with VWF and the Sortase A-dependent surface protein Clumping factor A (ClfA). VWF-vWbp-ClfA anchor S. aureus to vascular endothelium under shear stress.

  17. Severe hyponatraemia secondary to desmopressin therapy in von Willebrand's disease.

    PubMed

    Bertholini, D M; Butler, C S

    2000-04-01

    A 42-year-old female with von Willebrand's disease was managed with desmopressin and tranexamic acid to aid haemostasis following a vaginal hysterectomy. Severe acute hyponatraemia (134 to 108 mmol/l) developed over two days, culminating in a generalized tonic-clonic seizure and cerebral oedema. Fluid restriction, cessation of desmopressin and hypertonic saline administration led to a full recovery. Desmopressin is known to reduce free water elimination and produce hyponatraemia, but its extent and rate of development in this patient was surprising. Close monitoring of serum sodium and fluid balance is recommended in these patients.

  18. Von Willebrand factor and angiogenesis: basic and applied issues.

    PubMed

    Randi, A M; Laffan, M A

    2017-01-01

    The recent discovery that von Willebrand factor (VWF) regulates blood vessel formation has opened a novel perspective on the function of this complex protein. VWF was discovered as a key component of hemostasis, capturing platelets at sites of endothelial damage and synthesized in megakaryocytes and endothelial cells (EC). In recent years, novel functions and binding partners have been identified for VWF. The finding that loss of VWF in EC results in enhanced, possibly dysfunctional, angiogenesis is consistent with the clinical observations that in some patients with von Willebrand disease (VWD), vascular malformations can cause severe gastrointestinal (GI) bleeding. In vitro and in vivo studies indicate that VWF can regulate angiogenesis through multiple pathways, both intracellular and extracellular, although their relative importance is still unclear. Investigation of these pathways has been greatly facilitated by the ability to isolate EC from progenitors circulating in the peripheral blood of normal controls and patients with VWD. In the next few years, these will yield further evidence on the molecular pathways controlled by VWF and shed light on this novel and fascinating area of vascular biology. In this article, we will review the evidence supporting a role for VWF in blood vessel formation, the link between VWF dysfunction and vascular malformations causing GI bleeding and how they may be causally related. Finally, we will discuss how these findings point to novel therapeutic approaches to bleeding refractory to VWF replacement therapy in VWD.

  19. Interaction of the von Willebrand factor with platelets and thrombosis.

    PubMed

    Perutelli, P; Mori, P G

    1997-11-01

    The human von Willebrand factor (vWf) is a multimeric glycoprotein present in plasma, platelets, endothelial cells and subendothelium and synthesized in endothelial cells and megakaryocytes. vWf plays a pivotal role in the mechanisms of blood clotting and platelet thrombus formation; quantitative and qualitative abnormalities of vWf cause the most common congenital bleeding disorder in man, the von Willebrand disease. vWf stabilizes factor VIII and interacts with subendothelial components and with platelet membrane receptors. The multimeric structure of vWf provides an array of binding sites which allows multivalent interactions with its ligands, thus supporting the formation of stable platelet aggregates at the site of vascular injury, particularly under flow conditions characterized by high shear stress. In the last years, remarkable progress has been made toward understanding the structure of vWf protein and gene, and the elucidation of many structure-function relationships, which may result in improved therapeutic intervention for vWD patients, and in the development of effective strategies for antithrombotic therapy.

  20. von Willebrand factor, Jedi knight of the bloodstream.

    PubMed

    Springer, Timothy A

    2014-08-28

    When blood vessels are cut, the forces in the bloodstream increase and change character. The dark side of these forces causes hemorrhage and death. However, von Willebrand factor (VWF), with help from our circulatory system and platelets, harnesses the same forces to form a hemostatic plug. Force and VWF function are so closely intertwined that, like members of the Jedi Order in the movie Star Wars who learn to use "the Force" to do good, VWF may be considered the Jedi knight of the bloodstream. The long length of VWF enables responsiveness to flow. The shape of VWF is predicted to alter from irregularly coiled to extended thread-like in the transition from shear to elongational flow at sites of hemostasis and thrombosis. Elongational force propagated through the length of VWF in its thread-like shape exposes its monomers for multimeric binding to platelets and subendothelium and likely also increases affinity of the A1 domain for platelets. Specialized domains concatenate and compact VWF during biosynthesis. A2 domain unfolding by hydrodynamic force enables postsecretion regulation of VWF length. Mutations in VWF in von Willebrand disease contribute to and are illuminated by VWF biology. I attempt to integrate classic studies on the physiology of hemostatic plug formation into modern molecular understanding, and point out what remains to be learned.

  1. von Willebrand disease: advances in pathogenetic understanding, diagnosis, and therapy.

    PubMed

    Lillicrap, David

    2013-01-01

    von Willebrand disease (VWD) is the most common autosomally inherited bleeding disorder. The disease represents a range of quantitative and qualitative pathologies of the adhesive glycoprotein von Willebrand factor (VWF). The pathogenic mechanisms responsible for the type 2 qualitative variants of VWF are now well characterized, with most mutations representing missense substitutions influencing VWF multimer structure and interactions with platelet GPIbα and collagen and with factor VIII. The molecular pathology of type 3 VWD has been similarly well characterized, with an array of different mutation types producing either a null phenotype or the production of VWF that is not secreted. In contrast, the pathogenetic mechanisms responsible for type 1 VWD remain only partially resolved. In the hemostasis laboratory, the measurement of VWF:Ag and VWF:RCo are key components in the diagnostic algorithm for VWD, although the introduction of direct GPIbα-binding assays may become the functional assay of choice. Molecular genetic testing can provide additional benefit, but its utility is currently limited to type 2 and 3 VWD. The treatment of bleeding in VWD involves the use of desmopressin and plasma-derived VWF concentrates and a variety of adjunctive agents. Finally, a new recombinant VWF concentrate has just completed clinical trial evaluation and has demonstrated excellent hemostatic efficacy and safety.

  2. Prophylaxis in von Willebrand Disease: Coming of Age?

    PubMed

    Saccullo, Giorgia; Makris, Mike

    2016-07-01

    Although in most cases von Willebrand disease (VWD) is a mild disorder, a subgroup of patients experience frequent bleeding. In contrast to severe hemophilia in which prophylaxis is the accepted standard of care, this is less frequently used in VWD. Most type 1 VWD patients can be adequately managed with episodic desmopressin and tranexamic acid. In patients with more severe disease, especially those with type 3 VWD, joint bleeds, epistaxis, menorrhagia, and gastrointestinal bleeding are problematic and usually require treatment with von Willebrand factor/factor VIII (VWF/FVIII) concentrate. While in the past these patients were managed with on-demand VWF/FVIII concentrate, several recent reports have demonstrated the value of prophylactic treatment. Despite some uncertainties about the economic impact of treatment of severe VWD, prophylaxis with VWF concentrate should now be considered as the standard of care for the more severe end of the spectrum of affected individuals. The recent introduction of recombinant VWF concentrate is likely to improve the acceptability of prophylaxis in VWD.

  3. Acquired von Willebrand syndrome in patients with Gaucher disease.

    PubMed

    Mitrovic, Mirjana; Elezovic, Ivo; Miljic, Predrag; Suvajdzic, Nada

    2014-04-01

    Although various coagulation abnormalities occur in patients with Gaucher disease (GD), von Willebrand factor (vWF) deficiency has rarely been reported. A retrospective review of six treatment naïve cases with GD and concomitant vWF deficiency over a 12-year-period in a single center is presented. All patients had a personal history of prior hemorrhages. Based on both reduced level of vWF antigen (vWF:Ag, range 14-56%) and ristocetin cofactor activity (vWF:RCo, range 12-53%), with a vWF:RCo/Ag ratio >0.7, the diagnosis of type 1 von Willebrand disease was made in all six cases. During enzyme replacement therapy (ERT) of a 2-year duration all patients normalized their vWF:Ag levels. Based on the positive ERT effect on vWF:Ag levels, vWF deficiency was assumed to be acquired. It should be noted that beside vWF deficiency four patients with GD exhibited mild thrombocytopenia (range 81-131×10(9)/L) and three had additional hemostatic defects (reduced collagen platelet aggregation, FV, FXI and FXII deficiencies).

  4. Platelet-independent adhesion of calcium-loaded erythrocytes to von Willebrand factor

    PubMed Central

    Bierings, Ruben; Meems, Henriet; Mul, Frederik P. J.; Geerts, Dirk; Vlaar, Alexander P. J.; Voorberg, Jan; Hordijk, Peter L.

    2017-01-01

    Adhesion of erythrocytes to endothelial cells lining the vascular wall can cause vaso-occlusive events that impair blood flow which in turn may result in ischemia and tissue damage. Adhesion of erythrocytes to vascular endothelial cells has been described in multiple hemolytic disorders, especially in sickle cell disease, but the adhesion of normal erythrocytes to endothelial cells has hardly been described. It was shown that calcium-loaded erythrocytes can adhere to endothelial cells. Because sickle erythrocyte adhesion to ECs can be enhanced by ultra-large von Willebrand factor multimers, we investigated whether calcium loading of erythrocytes could promote binding to endothelial cells via ultra-large von Willebrand factor multimers. We used (immunofluorescent) live-cell imaging of washed erythrocytes perfused over primary endothelial cells at venular flow rate. Using this approach, we show that calcium-loaded erythrocytes strongly adhere to histamine-stimulated primary human endothelial cells. This adhesion is mediated by ultra-large von Willebrand factor multimers. Von Willebrand factor knockdown or ADAMTS13 cleavage abolished the binding of erythrocytes to activated endothelial cells under flow. Platelet depletion did not interfere with erythrocyte binding to von Willebrand factor. Our results reveal platelet-independent adhesion of calcium-loaded erythrocytes to endothelium-derived von Willebrand factor. Erythrocyte adhesion to von Willebrand factor may be particularly relevant for venous thrombosis, which is characterized by the formation of erythrocyte-rich thrombi. PMID:28249049

  5. Is the activated partial thromboplastin time suitable to screen for von Willebrand factor deficiencies?

    PubMed

    Lippi, Giuseppe; Franchini, Massimo; Poli, Giovanni; Salvagno, Gian Luca; Montagnana, Martina; Guidi, Gian Cesare

    2007-06-01

    The diagnostic approach to von Willebrand factor deficiencies is challenging and requires discretionary use of laboratory resources. Although extensive preoperative testing is not recommended, the activated partial thromboplastin time may be useful, especially in selected categories of patients. To establish the diagnostic sensitivity of this test to identify isolate von Willebrand factor deficiencies, 204 consecutive patients underwent a routine preoperative screening consisting of activated partial thromboplastin time, von Willebrand factor antigen, intrinsic pathway clotting factors activity, lupus anticoagulants and thrombin time. Thirty-seven patients were diagnosed with haemostasis disturbances other than von Willebrand factor deficiencies and were excluded from the evaluation. Isolated von Willebrand factor deficiency was diagnosed in 11 of the remaining 167 patients. A significant correlation was observed between von Willebrand factor antigen and activated partial thromboplastin time. Receiver operating characteristic curve analysis showed an area under the curve of 0.982 (95% confidence interval: 0.972-0.992; P < 0.001). At the 1.17 upper limit of the activated partial thromboplastin time, sensitivity and specificity were 100 and 85%, respectively, with negative and positive predictive values of 100 and 31%, respectively. These results demonstrate that activated partial thromboplastin time has an excellent diagnostic sensitivity and a satisfactory specificity for identifying isolated von Willebrand factor deficiencies.

  6. von Willebrand factor binds to the surface of dendritic cells and modulates peptide presentation of factor VIII

    PubMed Central

    Sorvillo, Nicoletta; Hartholt, Robin B.; Bloem, Esther; Sedek, Magdalena; Brinke, Anja ten; van der Zwaan, Carmen; van Alphen, Floris P.; Meijer, Alexander B.; Voorberg, Jan

    2016-01-01

    It has been proposed that von Willebrand factor might affect factor VIII immunogenicity by reducing factor VIII uptake by antigen presenting cells. Here we investigate the interaction of recombinant von Willebrand factor with immature monocyte-derived dendritic cells using flow cytometry and confocal microscopy. Surprisingly, von Willebrand factor was not internalized by immature dendritic cells, but remained bound to the cell surface. As von Willebrand factor reduces the uptake of factor VIII, we investigated the repertoire of factor VIII presented peptides when in complex with von Willebrand factor. Interestingly, factor VIII-derived peptides were still abundantly presented on major histocompatibility complex class II molecules, even though a reduction of factor VIII uptake by immature dendritic cells was observed. Inspection of peptide profiles from 5 different donors showed that different core factor VIII peptide sequences were presented upon incubation with factor VIII/von Willebrand factor complex when compared to factor VIII alone. No von Willebrand factor peptides were detected when immature dendritic cells were pulsed with different concentrations of von Willebrand factor, confirming lack of von Willebrand factor endocytosis. Several von Willebrand factor derived peptides were recovered when cells were pulsed with von Willebrand factor/factor VIII complex, suggesting that factor VIII promotes endocytosis of small amounts of von Willebrand factor by immature dendritic cells. Taken together, our results establish that von Willebrand factor is poorly internalized by immature dendritic cells. We also show that von Willebrand factor modulates the internalization and presentation of factor VIII-derived peptides on major histocompatibility complex class II. PMID:26635035

  7. Visualizing the von Willebrand factor/glycoprotein Ib-IX axis with a platelet-type von Willebrand disease mutation.

    PubMed

    Guerrero, Jose A; Kyei, Mark; Russell, Susan; Liu, Junling; Gartner, T Kent; Storrie, Brian; Ware, Jerry

    2009-12-24

    Platelet-type von Willebrand disease (PT-VWD) is a bleeding disorder of the platelet glycoprotein Ib-IX/von Willebrand factor (VWF) axis caused by mutations in the glycoprotein Ib-IX receptor that lead to an increased affinity with VWF. In this report, platelets from a mouse expressing a mutation associated with PT-VWD have been visualized using state-of-the art image collection and processing. Confocal analysis revealed that VWF bound to the surface of single platelets and bridging micro-aggregates of platelets. Surface-bound VWF appears as a large, linear structure on the surface of 50% of the PT-VWD platelets. In vivo thrombus formation after chemical injury to the carotid artery revealed a severe impairment to occlusion as a consequence of the PT-VWD mutation. In vitro stimulation of PT-VWD platelets with adenosine diphosphate or thrombin demonstrates a significant block in their ability to bind fibrinogen. The impairment of in vivo thrombus formation and in vitro fibrinogen binding are more significant than might be expected from the observed platelet binding to VWF polymers over a small portion of the plasma membrane. Visualization of the receptor/ligand interaction and characterization of a severe antithrombotic phenotype provide a new understanding on the molecular basis of bleeding associated with the PT-VWD phenotype.

  8. Variable content of von Willebrand factor mutant monomer drives the phenotypic variability in a family with von Willebrand disease.

    PubMed

    Chen, Junmei; Hinckley, Jesse D; Haberichter, Sandra; Jacobi, Paula; Montgomery, Robert; Flood, Veronica H; Wong, Randall; Interlandi, Gianluca; Chung, Dominic W; López, José A; Di Paola, Jorge

    2015-07-09

    Von Willebrand disease (VWD) is an inherited bleeding disorder characterized by incomplete penetrance and variable expressivity. We evaluated a 24-member pedigree with VWD type 2 caused by a T>G mutation at position 3911 that predicts a methionine to arginine (M1304R) change in the platelet-binding A1 domain of von Willebrand factor (VWF). This mutation manifests as an autosomal-dominant trait, with clinical and biochemical phenotypic variability among affected individuals, including differences in bleeding tendency and VWF quantity, activity, and multimer pattern. Sequencing of all VWF coding regions in 3 affected individuals did not identify additional mutations. When expressed in heterologous cells, M1304R was secreted in lower quantities, failed to drive formation of storage granules, and was defective in multimerization and platelet binding. When cotransfected in equal quantities with the wild-type complementary DNA, the mutant complementary DNA depressed VWF secretion, although multimerization was only mildly affected. A llama nanobody (AU/VWFa-11) that detects the mutant A1 domain demonstrated highly variable binding to VWF from different affected members, indicating that the VWF contained different percentages of mutant monomers in different individuals. Thus, the observed variability in VWD phenotypes could in part be determined by the extent of mutant monomer incorporation in the final multimer structure of plasma VWF.

  9. The role of von Willebrand factor in thrombus formation.

    PubMed

    Ruggeri, Zaverio M

    2007-01-01

    Von Willebrand factor (VWF) is a large multimeric glycoprotein produced in endothelial cells and megakaryocytes and present in subendothelial matrix, blood plasma and platelets. VWF mediates adhesion and aggregation of platelets at sites of vascular injury, processes that are critical for both haemostasis and thrombosis. Thrombus formation involves complex events that are influenced by different environmental conditions. Progress in understanding the structure and function of VWF and the mechanisms that underlie its interactions with platelets has led to important insight into the differentiation between normal haemostasis and pathological arterial thrombosis. The conventional view of signalling-induced platelet aggregation has recently been extended to include activation-independent aggregation. A novel mechanism has been demonstrated for initiating thrombus formation under high haemodynamic forces that involves alpha(IIb)beta(3)-independent platelet aggregation at the interface between immobilised and soluble VWF. This VWF-mediated process may be a key determinant of platelet accumulation in stenotic arteries leading to acute thrombotic occlusion.

  10. Using genetic diagnostics in hemophilia and von Willebrand disease.

    PubMed

    Swystun, Laura L; James, Paula

    2015-01-01

    Most bleeding disorders encountered in clinical practice will be diagnosed, at least initially, by phenotypic assays. However, since the characterization of the genes that encode coagulation factors in the 1980s, significant progress has been made in translating this knowledge for diagnostic and therapeutic purposes. For hemophilia A and B, molecular genetic testing to determine carrier status, prenatal diagnosis, and likelihood of inhibitor development or anaphylaxis to infused coagulation factor concentrates is an established component of comprehensive clinical management. In contrast, although significant recent advances in our understanding of the molecular genetic basis of von Willebrand disease (VWD) have allowed for the development of rational approaches to genetic diagnostics, questions remain about this complex genetic disorder and how to incorporate emerging knowledge into diagnostic strategies. This article will review the state-of-the-art for molecular diagnostics for both hemophilia and VWD.

  11. ADAMTS13 and von Willebrand factor in thrombotic thrombocytopenic purpura.

    PubMed

    Zheng, X Long

    2015-01-01

    Pathogenesis of thrombotic thrombocytopenic purpura (TTP) was a mystery for over half a century until the discovery of ADAMTS13. ADAMTS13 is primarily synthesized in the liver, and its main function is to cleave von Willebrand factor (VWF) anchored on the endothelial surface, in circulation, and at the sites of vascular injury. Deficiency of plasma ADAMTS13 activity (<10%) resulting from mutations of the ADAMTS13 gene or autoantibodies against ADAMTS13 causes hereditary or acquired (idiopathic) TTP. ADAMTS13 activity is usually normal or modestly reduced (>20%) in other forms of thrombotic microangiopathy secondary to hematopoietic progenitor cell transplantation, infection, and disseminated malignancy or in hemolytic uremic syndrome. Plasma infusion or exchange remains the initial treatment of choice to date, but novel therapeutics such as recombinant ADAMTS13 and gene therapy are under development. Moreover, ADAMTS13 deficiency has been shown to be a risk factor for the development of myocardial infarction, stroke, cerebral malaria, and preeclampsia.

  12. Terminal platelet production is regulated by von Willebrand factor.

    PubMed

    Poirault-Chassac, Sonia; Nguyen, Kim Anh; Pietrzyk, Audrey; Casari, Caterina; Veyradier, Agnes; Denis, Cecile V; Baruch, Dominique

    2013-01-01

    It is established that proplatelets are formed from mature megakaryocytes (MK) as intermediates before platelet production. Recently, the presence of proplatelets was described in blood incubated in static conditions. We have previously demonstrated that platelet and proplatelet formation is upregulated by MK exposure to high shear rates (1800 s(-1)) on immobilized von Willebrand factor (VWF). The purpose of the present study was to investigate whether VWF is involved in the regulation of terminal platelet production in blood. To this end, Vwf (-/-) mice, a model of severe von Willebrand disease, were used to create a situation in which blood cells circulate in a vascular tree that is completely devoid of VWF. Murine platelets were isolated from Vwf (-/-) and Vwf (+/+) blood, exposed to VWF at 1800 s(-1) in a microfluidic platform, and examined by means of videomicroscopy, as well as fluorescence and activation studies. Proplatelets became visible within 5 minutes, representing 38% of all platelets after 12 minutes and 46% after 28 min. The proportion of proplatelets was 1.8-fold higher in blood from Vwf(-/-) mice than from Vwf(+/+) mice, suggesting a role of VWF in vivo. Fragmentation of these proplatelets into smaller discoid platelets was also observed in real-time. Platelets remained fully activatable by thrombin. Compensation of plasmatic VWF following hydrodynamic gene transfer in Vwf(-/-) mice reduced the percentage of proplatelets to wild-type levels. A thrombocytopenic mouse model was studied in the flow system, 7 days after a single 5-FU injection. Compared to untreated mouse blood, a 2-fold increase in the percentage of proplatelets was detected following exposure to 1800 s(-1) on VWF of samples from mice treated with 5-FU. In conclusion, VWF and shear stress together appear to upregulate proplatelet reorganization and platelet formation. This suggests a new function for VWF in vivo as regulator of bloodstream thrombopoiesis.

  13. Acquired von Willebrand syndrome in children with aorticand pulmonary stenosis

    PubMed Central

    Binnetoğlu, Fatih Köksal; Babaoğlu, Kadir; Filiz, Şayegan Güven; Zengin, Emine; Sarper, Nazan; Altun, Gürkan; Kılıç, Suar Çakı

    2016-01-01

    Summary Introduction: This prospective study was planned to investigate the frequency and relationship of acquired von Willebrand syndrome (AVWS) with aortic and pulmonary stenosis in patients. Methods: A total of 84 children, ranging from two to 18 years of age, were enrolled in this study. Of these, 28 had isolated aortic stenosis, 32 had isolated pulmonary stenosis and 24 were healthy. Children with aortic and pulmonary stenosis associated with other congenital heart diseases were excluded. Children with hypothyroidism, renal or liver disease, malignancy or autoimmune disease were also excluded. Wholeblood count, blood group, factor VIII level, prothrombin time (PT), activated partial thromboplastin time (aPTT), von Willebrand factor antigen (VWF:Ag), ristocetin co-factor (VWF:RCo), and bleeding time using a platelet-function analyser (PFA-100) were performed in all patients. All of the children in the study underwent a detailed physical examination and echocardiographic evaluation. Results: A history of bleeding was positive in 18% of the aortic stenosis group, 9% of the pulmonary stenosis group, and 4% of the control group. Seven of 60 (12%) patients had laboratory findings that implied a diagnosis of AVWS, and two of these (28%) had a history of bleeding. The frequency of AVWS was 14% in patients with aortic stenosis and 9% in those with pulmonary stenosis. Conclusion: AVWS is not rare in stenotic obstructive cardiac diseases. A detailed history of bleeding should be taken from patients with valvular disease. Even if the history is negative, whole blood count, PT and aPTT should be performed. If necessary, PFA-100 closure time and further tests should be planned for the diagnosis of AVWS. PMID:27841910

  14. Postpartum von Willebrand factor levels in women with and without von Willebrand disease and implications for prophylaxis.

    PubMed

    James, A H; Konkle, B A; Kouides, P; Ragni, M V; Thames, B; Gupta, S; Sood, S; Fletcher, S K; Philipp, C S

    2015-01-01

    The aim of this study was to elucidate the fall in von Willebrand factor (VWF) and factor VIII activity (FVIII) after childbirth in women with and without von Willebrand disease (VWD). VWF:RCo, VWF:Ag, and FVIII were obtained in the third trimester of pregnancy, on admission for childbirth, and 10 times postpartum. Specimens were processed within 4 h and analysed centrally. Means were calculated at each time point. Forty women (40 pregnancies) without VWD and 32 women (35 pregnancies) with VWD were enrolled. 15/32 with VWD were treated (30% of those with type 1 and all of those with type 2) in 17 pregnancies. Treatments prior to delivery consisted of desmopressin (2/17), VWF concentrate (15/17) and after delivery VWF concentrate (16/17). Duration of treatment was 0-21 days (median 6). VWF levels peaked at 250% of baseline--4 h postpartum in women with VWD and 12 h postpartum in women without VWD. Thereafter, VWF levels fell rapidly, approached baseline at 1 week and reached baseline at 3 weeks. Except immediately postpartum, when the levels among treated cases were higher, levels among women with VWD appeared to parallel, but were lower than those among women without VWD. Levels were lowest among those who received treatment. VWF levels fall rapidly after childbirth. Except immediately postpartum, current treatment strategies do not raise VWF levels to the levels of women without VWD or even to the levels of women with milder, untreated VWD. Consequently, women with VWD may be at risk of postpartum haemorrhage despite treatment.

  15. Evaluation of a rapid von Willebrand factor activity latex immuno assay for monitoring of patients with von Willebrand disease (VWD) receiving DDAVP or VWF replacement therapy.

    PubMed

    Vinayagam, S; Simons, L R; Chowdary, P; Thurlow, P; Brooks, S V; Riddell, A F

    2014-07-01

    Haemostatic management of surgery in patients with von Willebrand disease (VWD) includes DDAVP or von Willebrand factor (VWF)-containing concentrates. Although the recommendations are for monitoring by VWF activity assays, it is quite common for clinicians to use factor VIII due usually to longer turnaround times required for VWF ristocetin cofactor assay (VWF:RCo) measurements. The aim of this study was to evaluate use of the rapid HaemosIL VWF activity (VWF:Act) latex immuno assay (LIA) on an automated coagulometer (ACL TOP(™) 700; Instrumentation Laboratory, Bedford, MA, USA) compared to platelet-based VWF:RCo assays in this setting. One hundred and sixty-seven plasma samples from 42 patients [Type 1 (n = 22), Type 2A (n = 2), Type 2B (n = 3), Type 2M (n = 10), Type 3 (n = 3)] and acquired von Willebrand syndrome (n = 2) with VWD treated with DDAVP or VWF-containing concentrates were included in the study. Method comparison and method bias were evaluated by Bland-Altman analysis (BA) and Passing and Bablok regression modelling respectively. BA of baseline samples (n = 39) showed a mean difference of -3.0 (±1.96 SD -25.2 to +19.4). Post (treatment) samples (n = 120) were separated into two groups. Group 1 contained samples with VWF:RCo levels 10 to ≤175 IU dL(-1) (n = 97) and group 2, samples with VWF:RCo levels >175 IU dL(-1) (n = 23). BA of group 1 postsamples showed a mean difference of +3.4 (±1.96 SD -44.6 to +51.5), and the BA of Group 2 samples was -23.9 (±1.96 SD -136.1 to +88.3). In conclusion, use of HaemosIL VWF:Act LIA test on an automated coagulometer is a reproducible and rapid assay that can be used as an alternative test for monitoring VWF replacement therapy, facilitating dose adjustments on a real-time basis.

  16. Identification and characterisation of mutations associated with von Willebrand disease in a Turkish patient cohort.

    PubMed

    Hampshire, Daniel J; Abuzenadah, Adel M; Cartwright, Ashley; Al-Shammari, Nawal S; Coyle, Rachael E; Eckert, Michaela; Al-Buhairan, Ahlam M; Messenger, Sarah L; Budde, Ulrich; Gürsel, Türkiz; Ingerslev, Jørgen; Peake, Ian R; Goodeve, Anne C

    2013-08-01

    Several cohort studies have investigated the molecular basis of von Willebrand disease (VWD); however, these have mostly focused on European and North American populations. This study aimed to investigate mutation spectrum in 26 index cases (IC) from Turkey diagnosed with all three VWD types, the majority (73%) with parents who were knowingly related. IC were screened for mutations using multiplex ligation-dependent probe amplification and analysis of all von Willebrand factor gene (VWF) exons and exon/intron boundaries. Selected missense mutations were expressed in vitro. Candidate VWF mutations were identified in 25 of 26 IC and included propeptide missense mutations in four IC (two resulting in type 1 and two in recessive 2A), all influencing VWF expression in vitro. Four missense mutations, a nonsense mutation and a small in-frame insertion resulting in type 2A were also identified. Of 15 type 3 VWD IC, 13 were homozygous and two compound heterozygous for 14 candidate mutations predicted to result in lack of expression and two propeptide missense changes. Identification of intronic breakpoints of an exon 17-18 deletion suggested that the mutation resulted from non-homologous end joining. This study provides further insight into the pathogenesis of VWD in a population with a high degree of consanguineous partnerships.

  17. Molecular and cellular biology of von Willebrand factor.

    PubMed

    Denis, Cécile V

    2002-01-01

    von Willebrand factor (VWF) is a plasma protein that performs 2 main functions in hemostasis: it mediates platelet adhesion to the injured vessel wall, and it carries and protects coagulation factor VIII. VWF is synthesized through a multistep process in endothelial cells and megakaryocytes as a very large polymer composed of identical disulfide-linked 250-kd subunits. In endothelial cells, VWF not only directs the formation of its own storage granules, the Weibel-Palade bodies, but it also acts as a chaperone molecule to direct other proteins, such as P-selectin, into these granules. Upon stimulation of the endothelium, the Weibel-Palade bodies will be translocated to the plasma membrane, and their contents will be secreted into the plasma milieu. The expression of VWF can be regulated at different levels by a number of genetic and environmental factors, resulting in control of its activity. New roles for VWF, especially in inflammatory processes, have recently been suggested, indicating that some aspects of this well-studied protein remain to be investigated.

  18. Characterization of the mouse von Willebrand factor promoter.

    PubMed

    Guan, J; Guillot, P V; Aird, W C

    1999-11-15

    Expression of the von Willebrand factor (vWF) gene is restricted to the endothelial and megakaryocyte lineages. Within the endothelium, expression of vWF varies between different vascular beds. We have previously shown that the human vWF promoter spanning a region between -2182 (relative to the start site of transcription) and the end of the first intron contains information for environmentally responsive, vascular bed-specific expression in the heart, skeletal muscle, and brain. In the present study, we cloned the mouse vWF (mvWF) promoter and studied its function in cultured endothelial cells and transgenic mice. In transient transfection assays, the mvWF gene was found to be regulated by distinct mechanisms in different endothelial cell subtypes. In independent lines of transgenic mice, an mvWF promoter fragment containing DNA sequences between -2645 and the end of the first intron directed endothelial cell-specific expression in the microvascular beds of the heart, brain, and skeletal muscle as well as the endothelial lining of the aorta. In 1 line of mice, reporter gene activity was also detected in bone marrow megakaryocytes. Taken together, these findings suggest that both the mouse and human vWF promoters are regulated by vascular bed-specific mechanisms.

  19. Functional property of von Willebrand factor under flowing blood.

    PubMed

    Sugimoto, Mitsuhiko; Miyata, Shigeki

    2002-01-01

    von Willebrand factor (vWF) is produced in megakaryocytes and endothelial cells, is stored in the alpha-granule of platelets and in the Weibel-Palade body of endothelial cells, and is present in plasma and vascular subendothelium. This huge protein with a unique multimeric structure plays a pivotal role in both hemostasis and pathological intravascular thrombosis, in which vWF contributes to both platelet adhesion/aggregation and blood coagulation through its multiple adhesive functions for the platelet membrane receptors, glycoprotein Ib-IX-V complex, integrin alphaIIbbeta3, heparin, various types of collagen, and coagulation factor VIII. Among various functions, the most characteristic feature of vWF is its determinant role on platelet thrombus formation under high-shear-rate conditions. Indeed, at in vivo rheological situations where platelets are flowing with high speed in the bloodstream, the only reaction that can initiate mural thrombogenesis is the interaction of vWF with platelet glycoprotein Ibalpha. The recent x-ray analysis of the crystal structure of various functional domains and functional studies of this protein under experimental flow conditions have rapidly advanced and revised our knowledge of the structure-function relationships of vWF, a key protein for hemostasis and arterial thrombosis.

  20. Keeping von Willebrand Factor under Control: Alternatives for ADAMTS13.

    PubMed

    Tersteeg, Claudia; Fijnheer, Rob; Pasterkamp, Gerard; de Groot, Philip G; Vanhoorelbeke, Karen; de Maat, Steven; Maas, Coen

    2016-02-01

    Von Willebrand factor (VWF) is one of the most important proteins of the hemostatic system. Its multimeric state is essential for its natural function to guide platelets to sites of injury. ADAMTS13 is the key protease that regulates the multimeric state of VWF. Without ADAMTS13, VWF multimers can grow to pathologically large sizes. This is a risk factor for the life-threatening condition thrombotic thrombocytopenic purpura (TTP). In this condition, VWF-rich thrombi occlude the microvasculature of various tissues. Intriguingly, a complete ADAMTS13 deficiency does not cause continuous TTP, either in patients or genetically targeted mice. Instead, TTP occurs in episodes of disease, separated by extended periods of remission. This indicates that regulating factors beyond ADAMTS13 are likely involved in this pathologic cascade of events. This raises the question of what really happens when ADAMTS13 is (temporarily) unavailable. In this review, we explore the possible role of complementary mechanisms that are capable of modifying the thrombogenic potential of VWF.

  1. Allosteric activation of ADAMTS13 by von Willebrand factor.

    PubMed

    Muia, Joshua; Zhu, Jian; Gupta, Garima; Haberichter, Sandra L; Friedman, Kenneth D; Feys, Hendrik B; Deforche, Louis; Vanhoorelbeke, Karen; Westfield, Lisa A; Roth, Robyn; Tolia, Niraj Harish; Heuser, John E; Sadler, J Evan

    2014-12-30

    The metalloprotease ADAMTS13 cleaves von Willebrand factor (VWF) within endovascular platelet aggregates, and ADAMTS13 deficiency causes fatal microvascular thrombosis. The proximal metalloprotease (M), disintegrin-like (D), thrombospondin-1 (T), Cys-rich (C), and spacer (S) domains of ADAMTS13 recognize a cryptic site in VWF that is exposed by tensile force. Another seven T and two complement C1r/C1s, sea urchin epidermal growth factor, and bone morphogenetic protein (CUB) domains of uncertain function are C-terminal to the MDTCS domains. We find that the distal T8-CUB2 domains markedly inhibit substrate cleavage, and binding of VWF or monoclonal antibodies to distal ADAMTS13 domains relieves this autoinhibition. Small angle X-ray scattering data indicate that distal T-CUB domains interact with proximal MDTCS domains. Thus, ADAMTS13 is regulated by substrate-induced allosteric activation, which may optimize VWF cleavage under fluid shear stress in vivo. Distal domains of other ADAMTS proteases may have similar allosteric properties.

  2. Development and validation of technical assays of von Willebrand disease in routine laboratory.

    PubMed

    Derdabi, Sara; Rozen, Laurence; Nagant, Carole; Demulder, Anne

    2016-12-01

    Von Willebrand disease (MW) is the most common constitutional bleeding disorders. It is caused by a quantitative or qualitative abnormality of the von Willebrand factor (VWF). The laboratory assessment of the disease combines a FVIII assay, and a determination of the antigen and activity of VWF. The analytical validation of VWF:Ag, VWF:Act, vWF:CB is reported in this work and demonstrates good test performance of all three assays, with a coefficient of variation lower than 10% for both the repeatability and reproducibility, stability with a deviation of less than 5% from the target value after six hours at room temperature. The dosages are linear through the following ranges: 2% to 346% for VWF:Ag, 3% to 170% for VWF:Act, and 0.07% to 259% for VWF:CB. The usual values determined on 32 control subjects are in the range of reference values published in the literature. However as the number of control samples tested is small, we will adopt the reference values of the literature of 50 to 200% in routine. The other functional test VWF:CB will be used in our daily practice to differentiate the type of 2M 2A type. However, given that the type 2M is extremely rare, we think it is rather aimed at specialized laboratories in which a large number of patients referred.

  3. A novel ELISA-based diagnosis of acquired von Willebrand disease with increased VWF proteolysis.

    PubMed

    Rauch, Antoine; Caron, Claudine; Vincent, Flavien; Jeanpierre, Emmanuelle; Ternisien, Catherine; Boisseau, Pierre; Zawadzki, Christophe; Fressinaud, Edith; Borel-Derlon, Annie; Hermoire, Sylvie; Paris, Camille; Lavenu-Bombled, Cécile; Veyradier, Agnès; Ung, Alexandre; Vincentelli, André; van Belle, Eric; Lenting, Peter J; Goudemand, Jenny; Susen, Sophie

    2016-05-02

    Von Willebrand disease-type 2A (VWD-2A) and acquired von Willebrand syndrome (AVWS) due to aortic stenosis (AS) or left ventricular assist device (LVAD) are associated with an increased proteolysis of von Willebrand factor (VWF). Analysis of VWF multimeric profile is the most sensitive way to assess such increased VWF-proteolysis. However, several technical aspects hamper a large diffusion among routine diagnosis laboratories. This makes early diagnosis and early appropriate care of increased proteolysis challenging. In this context of unmet medical need, we developed a new ELISA aiming a quick, easy and reliable assessment of VWF-proteolysis. This ELISA was assessed successively in a LVAD-model, healthy subjects (n=39), acquired TTP-patients (n=4), VWD-patients (including VWD-2A(IIA), n=22; VWD-2B, n=26; VWD-2A(IIE), n=21; and VWD-1C, n=8) and in AVWS-patients (AS, n=9; LVAD, n=9; and MGUS, n=8). A standard of VWF-proteolysis was specifically developed. Extent of VWF-proteolysis was expressed as relative percentage and as VWF proteolysis/VWF:Ag ratio. A speed-dependent increase in VWF-proteolysis was assessed in the LVAD model whereas no proteolysis was observed in TTP-patients. In VWD-patients, VWF-proteolysis was significantly increased in VWD-2A(IIA) and VWD-2B and significantly decreased in VWD-2A(IIE) versus controls (p< 0.0001). In AVWS-patients, VWF-proteolysis was significantly increased in AS- and LVAD-patients compared to controls (p< 0.0001) and not detectable in MGUS-patients. A significant increase in VWF-proteolysis was detected as soon as three hours after LVAD implantation (p< 0.01). In conclusion, we describe a new ELISA allowing a rapid and accurate diagnosis of VWF-proteolysis validated in three different clinical situations. This assay represents a helpful alternative to electrophoresis-based assay in the diagnosis and management of AVWS with increased VWF-proteolysis.

  4. Interaction of Platelet Membrane Receptors with von Willebrand Factor, Ristocetin, and the Fc Region of Immunoglobulin G

    PubMed Central

    Moore, Anne; Ross, Gordon D.; Nachman, Ralph L.

    1978-01-01

    The agglutination of human platelets by ristocetin and von Willebrand factor was inhibited by aggregated immunoglobulin (Ig)G and by Fc fragments of IgG, but not by Fab, F(ab′)2 or pFc fragments of IgG. Because this inhibition occurred with formalin-fixed platelets as well as with normal platelets, a generalized aggregation of fluid membrane components by Fc fragments was not responsible for this inhibition of ristocetin and von Willebrand factor-induced agglutination. Reciprocal inhibition of platelet Fc receptors was produced by prior incubation of platelets with von Willebrand factor and ristocetin. Sucrose density gradient ultracentrifugation studies demonstrated that aggregated IgG did not form fluid-phase complexes with von Willebrand factor and ristocetin. Furthermore, passage of von Willebrand factor and ristocetin through a column of immobilized heat-aggregated IgG did not alter platelet agglutinating activity which indicates that aggregated IgG did not inactivate von Willebrand factor or ristocetin. Thus, it was likely that the IgG-mediated interference with platelet agglutination by ristocetin and von Willebrand factor did not occur in the fluid phase but at the platelet surface. These studies suggest that the platelet membrane Fc receptor may be either a part of, or sterically related to, the membrane glycoprotein I complex that interacts with von Willebrand factor, and that occupation of one of these surface components blocks the availability of the other. PMID:309473

  5. P-selectin and von Willebrand factor in bovine mesenteric lymphatics: an immunofluorescent study.

    PubMed

    Di Nucci, A; Marchetti, C; Serafini, S; Piovella, F

    1996-03-01

    P-selectin (PADGEM, GMP-140, CD62) is an integral membrane protein specific to alpha granules of platelets and Weibel-Palade bodies of blood vascular endothelial cells. The presence in lymphatic endothelial cells of numerous Weibel-Palade bodies and their positivity to immunocytochemical reaction for von Willebrand factor have previously been characterized and described. Because von Willebrand factor and P-selectin codistribute in Weibel-Palade bodies of blood vascular endothelial cells we investigated the presence of both P-selectin and von Willebrand factor in lymphatic endothelium. Lymphatic vessels expressed positive reaction to immunocytochemical assay thereby demonstrating the presence of P-selectin in the endothelium. Distribution and intensity of the reaction were similar to those observed in bovine blood vascular endothelium.

  6. Multimeric analysis of von Willebrand factor in megakaryocytes.

    PubMed

    Kupinski, J M; Miller, J L

    1985-06-15

    Von Willebrand factor (vWF) is a glycoprotein that appears to play a major role in subserving the adhesion of platelets to subendothelium during hemostasis. Endothelial cells have been shown capable of synthesizing and releasing this large, multimeric glycoprotein that normally circulates in the plasma in association with the factor VIII coagulant molecule. Megakaryocytes, the precursor cells of blood platelets, also appear to possess vWF biosynthetic capacity, since cultured guinea pig megakaryocytes have been shown to produce a polypeptide precipitable by antibody to vWF. We now report a study of the multimeric structure of vWF in the megakaryocyte, as well as a quantitative comparison of megakaryocyte vWF with that of platelets and plasma in the guinea pig. Multimeric analysis on SDS agarose gels employing 125I-emu anti-human vWF revealed striking homology between human and guinea pig vWF. Platelets and megakaryocytes from the same guinea pigs contained vWF of highly comparable multimeric composition. Moreover, megakaryocytes and platelets both contained a subset of very high molecular weight multimers not present in plasma. Quantitation of vWF in megakaryocytes and platelets was achieved with a radioimmunoassay performed on detergent (NP-40) lysates of washed cells. These measurements showed that megakaryocytes and platelets contain 0.079 and 0.069 U of vWF per mg protein, respectively. The results of these studies suggest that megakaryocytes represent the primary, if in fact not sole, source of platelet vWF.

  7. von Willebrand factor storage requires intact prosequence cleavage site.

    PubMed

    Journet, A M; Saffaripour, S; Cramer, E M; Tenza, D; Wagner, D D

    1993-02-01

    Large multimers of the adhesive glycoprotein von Willebrand factor (vWf) are stored in endothelial cells in rod-shaped granules called Weibel-Palade bodies, while small multimers are secreted constitutively. Expression of pro-vWf in other cells with a regulated pathway of secretion, results in formation of vWf-containing storage granules that have a morphology similar to Weibel-Palade bodies. vWf expressed without its prosequence is not stored. To evaluate the importance of prosequence cleavage in vWf storage, the Arg at position -1, known to be necessary for cleavage, was mutated to Gly. Transfection of this cleavage mutant into two cell lines with a regulated pathway of secretion (RIN 5F and AtT-20 cells) led to the formation of large multimers. However, treatment of the cell lysates by the enzyme endoglycosidase H (Endo-H) did not reveal significant amounts of intracellular Endo-H-resistant vWf, which indicates the absence of a pool of stored processed vWf. In addition, no Weibel-Palade body-like structure was detected in these cells by immunofluorescence labeling with anti-vWf antiserum. Electron microscopy and immunocytochemistry of RIN 5F cells expressing the pro-vWf mutant confirmed the absence of Weibel-Palade body-like structures. In addition, anti-vWf-linked gold particles were found in the ER, occasionally in rounded granules and particularly in lysosomal structures which were abundant. We conclude that the formation of large aggregates is not sufficient to induce efficient vWf storage, and that the lack of cleavage of the prosequence may direct the mutant pro-vWf molecule to a degradative pathway. Therefore, the prosequence cleavage is a requirement for vWf storage.

  8. Evaluation of von Willebrand factor in COPD patients*

    PubMed Central

    Bártholo, Thiago Prudente; da Costa, Cláudia Henrique; Rufino, Rogério

    2014-01-01

    OBJECTIVE: To compare the absolute serum von Willebrand factor (vWF) levels and relative serum vWF activity in patients with clinically stable COPD, smokers without airway obstruction, and healthy never-smokers. METHODS: The study included 57 subjects, in three groups: COPD (n = 36); smoker (n = 12); and control (n = 9). During the selection phase, all participants underwent chest X-rays, spirometry, and blood testing. Absolute serum vWF levels and relative serum vWF activity were obtained by turbidimetry and ELISA, respectively. The modified Medical Research Council scale (cut-off score = 2) was used in order to classify COPD patients as symptomatic or mildly symptomatic/asymptomatic. RESULTS: Absolute vWF levels were significantly lower in the control group than in the smoker and COPD groups: 989 ± 436 pg/mL vs. 2,220 ± 746 pg/mL (p < 0.001) and 1,865 ± 592 pg/mL (p < 0.01). Relative serum vWF activity was significantly higher in the COPD group than in the smoker group (136.7 ± 46.0% vs. 92.8 ± 34.0%; p < 0.05), as well as being significantly higher in the symptomatic COPD subgroup than in the mildly symptomatic/asymptomatic COPD subgroup (154 ± 48% vs. 119 ± 8%; p < 0.05). In all three groups, there was a negative correlation between FEV1 (% of predicted) and relative serum vWF activity (r2 = −0.13; p = 0.009). CONCLUSIONS: Our results suggest that increases in vWF levels and activity contribute to the persistence of systemic inflammation, as well as increasing cardiovascular risk, in COPD patients. PMID:25210959

  9. Effect of von Willebrand factor on clot structure and lysis.

    PubMed

    Marchi, Rita; Rojas, Héctor

    2015-07-01

    Von Willebrand Factor (vWF) is constitutively secreted by the endothelium and incorporated in the fibrin clots under slow clotting conditions. The aim of the present work was to study the effect of vWF on clot structure and lysis. Purified fibrinogen was mixed with vWF or Tris-buffered saline and clotted with thrombin - activated factor XIII. Fibrin polymerization was followed by turbidity at 350 nm during 2.5 h. After this time, plasmin was added on the top of the clots, and the optical density (OD) was read until baseline values. vWF effect on network[Combining Acute Accent]s porosity was evaluated by permeation using the same clotting conditions as for fibrin polymerization. Clot structure was visualized and analyzed by laser scanning confocal microscopy (LSCM). The rate of fibrin polymerization was 1.47 mOD/s in the presence of vWF and 0.5 mOD/s when vWF was not added (P < 0.05). The fibrin lysis rate was approximately four times faster when vWF was added to fibrinogen. The fibrin network porosity was (20.4 ± 1.6) × 10 cm with vWF and (8.3 ± 1.2) × 10 cm without external vWF (P < 0.05). The analysis of LSCM images showed that vWF increased fibrin fibers diameter and the networks[Combining Acute Accent] pores size. In conclusion, vWF covalently crosslinked to fibrin modify its structure (increases fibrin diameter and the pores filling space of the meshwork) that accelerates the fibrin lysis rate.

  10. An Integrated Approach to von Willebrand Disease and Surgical Myocardial Revascularization

    PubMed Central

    Jiritano, Federica; Cristodoro, Lucia; Bevacqua, Egidio; Malta, Emanuele; Mastroroberto, Pasquale

    2015-01-01

    Cardiac surgery in patients with preexisting bleeding disorders can be a challenge. Cardiopulmonary bypass can lead to bleeding disorders, above all in patients with coagulopathy. We report the case of a 42-year-old woman, with type I von Willebrand disease, who underwent off-pump coronary artery bypass grafting. Beating heart surgery associated with an adequate replacement of von Willebrand factor and factor VIII levels were chosen to prevent bleeding disorders. Her postoperative course was uneventful and she was discharged home after 5 postoperative days. PMID:26693126

  11. Molecular and clinical profile of von Willebrand disease in Spain (PCM-EVW-ES): Proposal for a new diagnostic paradigm.

    PubMed

    Batlle, Javier; Pérez-Rodríguez, Almudena; Corrales, Irene; López-Fernández, Maria Fernanda; Rodríguez-Trillo, Ángela; Lourés, Esther; Cid, Ana Rosa; Bonanad, Santiago; Cabrera, Noelia; Moret, Andrés; Parra, Rafael; Mingot-Castellano, María Eva; Balda, Ignacia; Altisent, Carmen; Pérez-Montes, Rocío; Fisac, Rosa María; Iruín, Gemma; Herrero, Sonia; Soto, Inmaculada; de Rueda, Beatriz; Jiménez-Yuste, Victor; Alonso, Nieves; Vilariño, Dolores; Arija, Olga; Campos, Rosa; Paloma, María José; Bermejo, Nuria; Toll, Teresa; Mateo, José; Arribalzaga, Karmele; Marco, Pascual; Palomo, Ángeles; Sarmiento, Lizheidy; Iñigo, Belén; Nieto, María del Mar; Vidal, Rosa; Martínez, María Paz; Aguinaco, Reyes; César, Jesús María; Ferreiro, María; García-Frade, Javier; Rodríguez-Huerta, Ana María; Cuesta, Jorge; Rodríguez-González, Ramón; García-Candel, Faustino; Cornudella, Rosa; Aguilar, Carlos; Borràs, Nina; Vidal, Francisco

    2016-01-01

    The diagnosis of von Willebrand disease (VWD) remains difficult in a significant proportion of patients. A Spanish multicentre study investigated a cohort of 556 patients from 330 families who were analysed centrally. VWD was confirmed in 480. Next generation sequencing (NGS) of the whole coding VWF was carried out in all recruited patients, compared with the phenotype, and a final diagnosis established. A total of 238 different VWF mutations were found, 154 were not included in the Leiden Open Variation Database (LOVD). Of the patients, 463 were found to have VWF mutation/s. A good phenotypic/genotypic association was estimated in 96.5% of the patients. One hundred seventy-four patients had two or more mutations. Occasionally a predominant phenotype masked the presence of a second abnormality. One hundred sixteen patients presented with mutations that had previously been associated with increased von Willebrand factor (VWF) clearance. RIPA unavailability, central phenotypic results disagreement and difficult distinction between severe type 1 and type 3 VWD prevented a clear diagnosis in 70 patients. The NGS study facilitated an appropriate classification in 63 of them. The remaining seven patients presented with a VWF novel mutation pending further investigation. In five patients with a type 3 and two with a type 2A or 2B phenotype with no mutation, an acquired von Willebrand syndrome (AVWS) was suspected/confirmed. These data seem to support NGS as a first line efficient and faster paradigm in VWD diagnosis.

  12. Human von Willebrand factor/factor VIII concentrates in the management of pediatric patients with von Willebrand disease/hemophilia A

    PubMed Central

    Castaman, Giancarlo; Linari, Silvia

    2016-01-01

    Several plasma-derived intermediate and high-purity concentrates containing von Willebrand factor (VWF) and factor VIII (FVIII) are currently available. The main role of these products in the management of the pediatric population is represented by the replacement therapy in patients with severe or intermediate forms of von Willebrand disease, in whom other treatments are ineffective or contraindicated. Another important role of VWF/FVIII concentrates in children may be their use in immune tolerance induction (ITI) protocols. ITI is particularly recommended for hemophilia A children who have developed an inhibitor against FVIII, currently the most serious complication of substitutive treatment in hemophilia. Although recombinant concentrates may represent the preferred option in children with hemophilia A, VWF/FVIII concentrates may offer an advantage in rescuing patients who failed previous ITI. PMID:27445481

  13. Human von Willebrand factor/factor VIII concentrates in the management of pediatric patients with von Willebrand disease/hemophilia A.

    PubMed

    Castaman, Giancarlo; Linari, Silvia

    2016-01-01

    Several plasma-derived intermediate and high-purity concentrates containing von Willebrand factor (VWF) and factor VIII (FVIII) are currently available. The main role of these products in the management of the pediatric population is represented by the replacement therapy in patients with severe or intermediate forms of von Willebrand disease, in whom other treatments are ineffective or contraindicated. Another important role of VWF/FVIII concentrates in children may be their use in immune tolerance induction (ITI) protocols. ITI is particularly recommended for hemophilia A children who have developed an inhibitor against FVIII, currently the most serious complication of substitutive treatment in hemophilia. Although recombinant concentrates may represent the preferred option in children with hemophilia A, VWF/FVIII concentrates may offer an advantage in rescuing patients who failed previous ITI.

  14. Function of von Willebrand factor after crossed bone marrow transplantation between normal and von Willebrand disease pigs: effect on arterial thrombosis in chimeras.

    PubMed Central

    Nichols, T C; Samama, C M; Bellinger, D A; Roussi, J; Reddick, R L; Bonneau, M; Read, M S; Bailliart, O; Koch, G G; Vaiman, M

    1995-01-01

    von Willebrand factor (vWF) is essential for the induction of occlusive thrombosis in stenosed and injured pig arteries and for normal hemostasis. To separate the relative contribution of plasma and platelet vWF to arterial thrombosis, we produced chimeric normal and von Willebrand disease pigs by crossed bone marrow transplantation; von Willebrand disease (vWD) pigs were engrafted with normal pig bone marrow and normal pigs were engrafted with vWD bone marrow. Thrombosis developed in the chimeric normal pigs that showed normal levels of plasma vWF and an absence of platelet vWF; but no thrombosis occurred in the chimeric vWD pigs that demonstrated normal platelet vWF and an absence of plasma vWF. The ear bleeding times of the chimeric pigs were partially corrected by endogenous plasma vWF but not by platelet vWF. Our animal model demonstrated that vWF in the plasma compartment is essential for the development of arterial thrombosis and that it also contributes to the maintenance of bleeding time and hemostasis. Images Fig. 2 Fig. 3 PMID:7708664

  15. Acquired von Willebrand syndrome in a patient with monoclonal gammopathy of undetermined significance.

    PubMed

    Puronen, Camille E; Josephson, Neil C; Broudy, Virginia C

    2013-06-01

    Acquired von Willebrand syndrome (AVWS) is a rare bleeding disorder that typically presents as mucocutaneous bleeding in individuals with no personal or family history of bleeding disorder. Here we present a case in which a patient presented with profound epistaxis and was found to have AVWS in the setting of monoclonal gammopathy of undetermined significance (MGUS).

  16. Definition of the affinity of binding between human von Willebrand factor and coagulation factor VIII.

    PubMed

    Ganz, P R; Atkins, J S; Palmer, D S; Dudani, A K; Hashemi, S; Luison, F

    1991-10-15

    Factor VIII and von Willebrand factor are two plasma proteins essential for effective hemostasis. In vivo, they form a non-covalent complex whose association appears to be metal ion dependent. However, a precise definition of the nature of the molecular forces governing their association remains to be defined, as does their binding affinity. In this paper we have determined the dissociation constant and stoichiometry for Factor VIII binding to immobilized von Willebrand factor. The data demonstrate that these proteins interact saturably and with relatively high affinity. Computer assisted analyses of the Scatchard data favour a two site binding model. The higher affinity site was found to have a Kd of 62 (+/- 13) x 10(-12) M while that of the lower affinity site was 380 (+/- 92) x 10(-12) M. The density of Factor VIII binding sites (Bmax) present on von Willebrand factor was 31 (+/- 3) pM for the high affinity binding site and 46 (+/- 6) pM for the lower site, corresponding to a calculated Factor VIII: von Willebrand factor binding ratio of 1:33 and 1:23, respectively.

  17. Differential localization of P-selectin and von Willebrand factor during megakaryocyte maturation.

    PubMed

    Zingariello, M; Fabucci, M E; Bosco, D; Migliaccio, A R; Martelli, F; Rana, R A; Zetterberg, E

    2010-04-28

    An important step in megakaryocyte maturation is the appropriate assembly of at least two distinct subsets of alpha-granules. The mechanism that sorts the alpha-granule components into distinct structures and mediates their release in response to specific stimuli is now emerging. P-selectin and von Willebrand factor are two proteins present in the alpha-granules that recognize P-selectin glycoprotein ligand on neutrophils and collagen in the subendothelial matrix. These proteins may play an important role in determining the differential release of the alpha-granule contents in response to external stimuli. If P-selectin and von Willebrand factor are localized in the same or different alpha-granules is not known. To clarify this question, we analyzed by immunoelectron microscopy the localization of von Willebrand factor and P-selectin during the maturation of wild-type and Gata1(low) megakaryocytes induced in vivo by treating animals with thrombopoietin. Gata1(low) is a hypomorphic mutation that blocks megakaryocyte maturation, reduces the levels of von Willebrand factor expression and displaces P-selectin on the demarcation membrane system. The maturation block induced by this mutation is partially rescued by treatment in vivo with thrombopoietin. In immature megakaryocytes, both wild-type and Gata1(low), the two receptors were co-localized in the same cytoplasmic structures. By contrast, the two proteins were segregated to separate alpha-granule subsets as the megakaryocytes matured. These observations support the hypothesis that P-selectin and von Willebrand factor may ensure differential release of the alpha-granule content in response to external stimuli.

  18. The natural history of occult or angiodysplastic gastrointestinal bleeding in von Willebrand disease.

    PubMed

    Makris, M; Federici, A B; Mannucci, P M; Bolton-Maggs, P H B; Yee, T T; Abshire, T; Berntorp, E

    2015-05-01

    Recurrent gastrointestinal bleeding is one of the most challenging complications encountered in the management of patients with von Willebrand disease (VWD). The commonest cause is angiodysplasia, but often no cause is identified due to the difficulty in making the diagnosis. The optimal treatment to prevent recurrences remains unknown. We performed a retrospective study of VWD patients with occult or angiodysplastic bleeding within the setting of the von Willebrand Disease Prophylaxis Network (VWD PN) to describe diagnostic and treatment strategies. Centres participating in the VWD PN recruited subjects under their care with a history of congenital VWD and gastrointestinal (GI) bleeding due to angiodysplasia, or cases in which the cause was not identified despite investigation. Patients with acquired von Willebrand syndrome or those for whom the GI bleeding was due to another cause were excluded. Forty-eight patients from 18 centres in 10 countries were recruited. Seven individuals had a family history of GI bleeding and all VWD types except 2N were represented. Angiodysplasia was confirmed in 38%, with video capsule endoscopy and GI tract endoscopies being the most common methods of making the diagnosis. Recurrent GI bleeding in VWD is associated with significant morbidity and required hospital admission on up to 30 occasions. Patients were treated with multiple pharmacological agents with prophylactic von Willebrand factor concentrate being the most efficient in preventing recurrence of the GI bleeding. The diagnosis and treatment of recurrent GI bleeding in congenital VWD remains challenging and is associated with significant morbidity. Prophylactic treatment with von Willebrand factor concentrate was the most effective method of preventing recurrent bleeding but its efficacy remains to be confirmed in a prospective study.

  19. Von Willebrand disease in sub-Saharan Africa: a first severe case reported in Cameroon.

    PubMed

    Tagny, Claude T; Balôgôg, Pauline N; Boehlen, Francoise; Mbanya, Dora

    2016-10-01

    In Cameroon, the Yaoundé Hemophilia Treatment Center (HTC) has so far recorded 121 cases of hemophilia and only 10 cases of von Willebrand disease (VWD). We report the case of a 16-year-old girl, living in the north of Cameroon. She presented with severe meno-metrorrhagia, which had increased drastically within the past 3 months, associated more recently by gum bleeding and epistaxis. The coagulation screen showed a prolonged bleeding time. The clinical profile of this young girl and the findings of less than 5% for von Willebrand factor (VWF):Ag and 10% for VWF Ristocetin cofactor suggests a type 3 VWD. Screening for VWF:Ag and other inherited bleeding disorders in Cameroon is still rudimentary, and although VWD is more common than hemophilia, we report this case to highlight some of the challenges faced in resource-limited contexts.

  20. Current controversies in the diagnosis and management of von Willebrand disease

    PubMed Central

    2015-01-01

    Von Willebrand disease (VWD) is the most common inherited bleeding disorder in the world. The spectrum of VWD spans quantitative and qualitative deficiencies of von Willebrand factor (VWF), a platelet adhesive protein. It manifests primarily as mucocutaneous bleeding, but severely affected patients may suffer soft tissue bleeding and hemarthroses. There is disagreement in the multiple guidelines published regarding diagnosis, especially of type 1 VWD, which also remains the most opaque with respect to molecular characterization. Treatment with desmopressin (DDAVP) is most effective in type 1 VWD, but regimens are not standardized. It is not clear which type 2 VWD patients with qualitative deficiencies can be treated with DDAVP and which ones should receive VWF concentrates. No guidelines stipulate which patients might benefit from prophylactic VWF infusions and how they should be dosed. These are some current controversies in VWD that are discussed in this review. PMID:26288715

  1. Refractory bleeding from intestinal angiodysplasias successfully treated with danazol in three patients with von Willebrand disease.

    PubMed

    Botero, Juliana Perez; Pruthi, Rajiv K

    2013-12-01

    von Willebrand disease (VWD) is associated with development of gastrointestinal (GI) vascular malformations that lead to chronic GI bleeding. Conventional management, including von Willebrand factor concentrate replacement and endoscopic ablation or bowel resection, does not consistently reduce hemorrhage. We describe three patients with VWD for whom conventional management failed to control GI bleeding. We retrospectively reviewed medical records of patients with VWD and GI bleeding. After patients began treatment with danazol, we observed long-term reductions in GI bleeding and packed red blood cell transfusion requirements. One patient had severe liver toxicity and was found to have concomitant primary biliary cirrhosis. Danazol use may be considered in patients with VWD and GI bleeding due to angiodysplasia that otherwise fails to respond to conventional treatment; the primary aim of treatment is to reduce transfusion dependence. The benefits are variable and possibly transient. Monitoring for toxicity is important when this treatment is pursued.

  2. Von Willebrand Factor Abnormalities Studied in the Mouse Model: What We Learned about VWF Functions

    PubMed Central

    Casari, Caterina; Lenting, Peter J.; Christophe, Olivier D.; Denis, Cécile V.

    2013-01-01

    Up until recently, von Willebrand Factor (VWF) structure-function relationships have only been studied through in vitro approaches. A powerful technique known as hydrodynamic gene transfer, which allows transient expression of a transgene by mouse hepatocytes, has led to an important shift in VWF research. Indeed this approach has now enabled us to transiently express a number of VWF mutants in VWF-deficient mice in order to test the relative importance of specific residues in different aspects of VWF biology and functions in an in vivo setting. As a result, mice reproducing various types of von Willebrand disease have been generated, models that will be useful to test new therapies. This approach also allowed a more precise identification of the importance of VWF interaction with subendothelial collagens and with platelets receptors in hemostasis and thrombosis. The recent advances gathered from these studies as well as the pros and cons of the technique will be reviewed here. PMID:23936618

  3. Acquired von Willebrand disease and multiple myeloma: a case report of a breast cancer survivor.

    PubMed

    Jin, Ning; Salahuddin, Farah F; Nesbitt, John A

    2014-12-01

    Acquired von Willebrand disease (aVWD) is rare disease and is associated with a variety of underlying diseases. We report a case of aVWD in the setting of multiple myeloma. The patient was a 63-year-old female with breast cancer in remission who was admitted for symptomatic anemia. She was diagnosed with multiple myeloma. She also had subcutaneous bleeding before admission. Laboratory studies revealed isolated prolongation of the activated partial thromboplastin time, which corrected in a mixing study. Her factor VIII activity, von Willebrand factor (VWF) Ag, and VWF activity were low. VWF multimer study confirmed the patient had aVWD. The treatment of aVWD is discussed in this article, including the treatment of underlying diseases, and acute management in emergent situations. An intriguing question in this case is whether the patient's multiple myeloma is a chemotherapy-induced hematological malignancy or a second primary malignancy.

  4. Von Willebrand disease - the 'Dos' and 'Don'ts' in surgery.

    PubMed

    Miesbach, Wolfgang; Berntorp, Erik

    2017-02-01

    Von Willebrand disease (VWD) is the most common genetic bleeding disorder. VWD is caused by a deficiency or dysfunction of von Willebrand factor (VWF), a plasma protein that mediates the initial adhesion of platelets at sites of vascular injury and binds and stabilises coagulation factor VIII (FVIII) in the blood. Prophylaxis of surgical bleeding in patients with VWD requires consideration of the individual situation, including the type of procedure and the bleeding rate, before decisions about treatment type, dose, duration and adjunctive therapy with antifibrinolytics or antithrombotic prophylaxis can be made. Although desmopressin (DDAVP)-stimulated release of endogenous VWD is an effective treatment strategy in many patients, plasma concentrates containing VWF are the preferred option for most patients undergoing surgical procedures. Recommendations for the management of surgery in patients with VWD are summarised, including the severity of VWD and the type of the surgical procedure.

  5. Up to date concepts about Von Willebrand disease and the diagnose of this hemostatic disorder

    PubMed Central

    Buga-Corbu, I; Arion, C

    2014-01-01

    Abstract The authors review the current data in literature regarding the recent knowledge about hemostase, coagulation and clinical and laboratory diagnostic algorithms of hemostatic disorders. They also present the pathological classification of bleeding disorders - the basis to clinical approach of these diseases. Abbreviations: AD=autosomal dominant; Ag=antigen; DNA=deoxyribonucleic acid; ADAMTS13=serum metalloproteinase; AR=autosomal recessive; Arg=arginine; RNA=ribonucleic acid; VWD=von Willebrand disease; Cys=cysteine; C1—C9=factors of the seric complement; ELISA=enzyme linked immuno assay; FI---FXIII=plasmatic factors of coagulation; Glu=glutamines; Pg=platelet glycoprotein; HMW=high molecular weight; IL=interleukin; SLE=systemic lupus erythematosus; Met=methionine; PFA=automated study test of platelets aggregation; RCo=ristocetin cofactor; RI PA=ristocetin induced platelet aggregation; Tyr=tyrosine; VWF= von Willebrand factor PMID:25408749

  6. Differential proteolytic activation of factor VIII-von Willebrand factor complex by thrombin

    SciTech Connect

    Hill-Eubanks, D.C.; Parker, C.G.; Lollar, P. )

    1989-09-01

    Blood coagulation factor VIII (fVIII) is a plasma protein that is decreased or absent in hemophilia A. It is isolated as a mixture of heterodimers that contain a variably sized heavy chain and a common light chain. Thrombin catalyzes the activation of fVIII in a reaction that is associated with cleavages in both types of chain. The authors isolated a serine protease from Bothrops jararacussu snake venom that catalyzes thrombin-like heavy-chain cleavage but not light-chain cleavage in porcine fVIII as judged by NaDodSO{sub 4}/PAGE and N-terminal sequence analysis. Using a plasma-free assay of the ability of activated {sup 125}I-fVIII to function as a cofactor in the activation of factor X by factor IXa, they found that fVIII is activated by the venom enzyme. The venom enzyme-activated fVIII was isolated in stable form by cation-exchange HPLC. von Willebrand factor inhibited venom enzyme-activated fVIII but not thrombin-activated fVIII. These results suggest that the binding of fVIII to von Willebrand factor depends on the presence of an intact light chain and that activated fVIII must dissociate from von Willebrand factor to exert its cofactor effect. Thus, proteolytic activation of fVIII-von Willebrand factor complex appears to be differentially regulated by light-chain cleavage to dissociate the complex and heavy-chain cleavage to activate the cofactor function.

  7. Isoelectric focusing of human von Willebrand factor in urea-agarose gels

    SciTech Connect

    Fulcher, C.A.; Ruggeri, Z.M.; Zimmerman, T.S.

    1983-02-01

    An analytical technique has been developed for the isoelectric focusing (IEF) of plasma von Willebrand factor (vWF) in agarose gels containing urea. Under these conditions, vWF freely enters the gel and focuses without artifact. The focused vWF is visualized by staining fixed gels with /sup 125/I-labeled affinity-purified heterologous antibody. Utilizing a pH gradient of 5.0-6.5, normal vWF in plasma or purified preparations focuses into at least three bands with apparent isoelectric points (pI) between pH 5.7 and 5.9. A reproducible difference in the IEF pattern of vWF has been established between normal plasmas and those of individuals with variant von Willebrand's disease (vWd) type IIA and type IIB. In type IIA, vWF has a distinctly lower pI than normal. This difference may be related to the presence of smaller vWF multimers in IIA plasma because forms of vWF of corresponding size contained in normal cryoprecipitate supernatant have a similar pI. Type IIB von Willebrand factor has a pI intermediate between normal and IIA. Neuraminidase treatment of plasma samples before IEF results in an increase in pI in normal, type IIA, and type IIB vWF. The data suggest that none of the 16 type IIA and 9 IIB plasmas studied here contain significantly decreased amounts of sialic acid.

  8. How I treat type 2 variant forms of von Willebrand disease.

    PubMed

    Tosetto, Alberto; Castaman, Giancarlo

    2015-02-05

    Type 2 von Willebrand disease (VWD) includes a wide range of qualitative abnormalities of von Willebrand factor structure and function resulting in a variable bleeding tendency. According to the current classification, 4 different subtypes can be identified, each with distinctive phenotypic and therapeutic characteristics. Current available laboratory methods allow a straightforward approach to VWD subtyping, and although the precise molecular characterization remains complex, it is not required for appropriate treatment of the vast majority of cases. Desmopressin can be useful only in a few type 2 cases compared with patients with actual quantitative deficiency (type 1), most often in variants with a nearly normal multimeric pattern (type 2M). However, since no laboratory test accurately predicts response to desmopressin, a trial test should always be performed in all type 2 VWD patients, with the exception of type 2B ones. Replacement therapy with plasma-derived von Willebrand factor-factor VIII concentrates represents the safe mainstay of treatment of all patients, particularly those not responding to desmopressin or requiring a sustained hemostatic correction because of major surgery or bleeding. A significant patient bleeding history correlates with increased bleeding risk and should be considered in tailoring the optimal antihemorrhagic prophylaxis in the individual patient.

  9. Changes in bleeding patterns in von Willebrand disease after institution of long-term replacement therapy: results from the von Willebrand Disease Prophylaxis Network.

    PubMed

    Holm, Elena; Abshire, Thomas C; Bowen, Joel; Álvarez, M Teresa; Bolton-Maggs, Paula; Carcao, Manuel; Federici, Augusto B; Gill, Joan Cox; Halimeh, Susan; Kempton, Christine; Key, Nigel S; Kouides, Peter; Lail, Alice; Landorph, Andrea; Leebeek, Frank; Makris, Michael; Mannucci, Pier; Mauser-Bunschoten, Eveline P; Nugent, Diane; Valentino, Leonard A; Winikoff, Rochelle; Berntorp, Erik

    2015-06-01

    Clinically, the leading symptom in von Willebrand disease (VWD) is bleeding, chiefly of mucosal type, for example, epistaxis, gingival, or gastrointestinal bleeding, and menorrhagia. In severe forms of VWD with secondary deficiency of factor VIII, spontaneous joint bleeding, resembling that observed in severe haemophilia A, may also be observed. The bleeding patterns of VWD can affect quality of life, and may be life-threatening. The von Willebrand Disease Prophylaxis Network is an international study group formed with the goal of investigating the role of prophylaxis in clinically severe VWD. The objective of the present study is to investigate the response to prophylaxis focusing primarily on epistaxis, joint bleeding, gastrointestinal bleeding, and heavy bleeding associated with menses. Data from 105 subjects, 10 enrolled in a prospective study and 95 in a retrospective study between 2008 and 2013, were available for analysis. The median annualized rate reductions in bleeding were significant for epistaxis (P < 0.0001), gastrointestinal bleeding (P = 0.0003), joint bleeding (P < 0.0001), and menorrhagia (P = 0.008). Doses on a group level were approximately the same prior to and during prophylaxis, but more patients with gastrointestinal bleeding had prophylaxis three or more times per week as well as higher dosages. Our study, which primarily used retrospective data, indicates that prospective studies are needed to better delineate the doses and dose intervals that should be used for prophylactic treatment of VWD.

  10. Characterization of the von Willebrand factor gene (VWF) in von Willebrand disease type III patients from 24 families of Swedish and Finnish origin

    SciTech Connect

    Zhang, Z.P.; Blomback, M.; Egberg, N.; Falk, G.; Anvret, M. )

    1994-05-01

    Twenty-four patients with von Willebrand disease type III were screened for mutations in the von Willebrand factor (VWF) gene using the PCR technique, followed by direct sequencing. More than 250 kb of genomic DNA were sequenced, including the promoter and coding regions (52 exons) of the VWF gene from 24 patients. In addition to the previously reported mutations of a single cytosine deletion in exon 18 and the nonsense mutations in exons 28, 32, and 45, nine new mutations were detected: two nonsense mutations in exons 15 and 16, one allele with a thymidine insertion in exon 14, one allele with a cytosine insertion in exon 28, one 20-bp deletion in exon 15, one mutation in the donor splice site of exon 43, and three missense mutations in exons 28, 49, and 51. Forty-two mutant chromosomes were identified (42/48); 11 probands are homozygous for the mutations, and 8 are compound heterozygous. In addition, a new subfamily of the Alu sequence in the promoter region and 10 new polymorphisms were identified. 15 refs., 3 figs., 3 tabs.

  11. The Prevalence of von Willebrand Disease and Significance of in Vitro Bleeding Time (PFA-100) in von Willebrand Disease Screening in the İzmir Region.

    PubMed

    Sap, Fatih; Kavaklı, Tülay; Kavaklı, Kaan; Dizdarer, Ceyhun

    2013-03-01

    Amaç: von Willebrand hastalığı (vWH) en sık kalıtsal kanama bozukluğudur. Bu çalışmanın amacı, İzmir’de adolesanlarda vWH’nın sıklığını saptamak ve tarama yöntemi olarak PFA-100’ün bu hastalığı saptamada duyarlılık ve özgüllüğünü belirlemektir. Gereç ve Yöntemler: Çalışmamız İzmir İli’nde adolesanlarda Ekim 2006-Mart 2007 tarihleri arasında yapıldı. Yaşları 14-19 arasında olan yaklaşık 1500 lise öğrencisinin çalışmaya dahil edilmesi planlandı. Kanama diyatezini sorgulamaya yönelik hazırlanan anket formlarının cevapları 1339 (512 erkek, 827 kız) bireyden geri toplanabildi. Muhtemel kanama diyatezi olduğu düşünülen 40 bireyden yazılı onam formları alınarak gerekli laboratuvar testleri alındı. Bulgular: von Willebrand faktör antijen (vWF:Ag) ve ristosetin kofaktör aktivite (vWF:RCo) düzeyi ve kanama semptomları esas alınarak 14 bireyde (4 erkek, 10 kız) von Willebrand Hastalığı tip-1 tespit edildi (prevalans %1,04). Bu hastalarda saptanan en sık kanama semptomunun burun kanaması olduğu (10/14) görüldü. PFA-100 ile yapılan taramada ise 14 hastadan 3’ünde iki kartuşta da (Col/ADP ve Col/Epi) uzama görüldü. PFA-100’ün von Willebrand Hastalığı’nı saptamadaki duyarlılığı %21,4 ve özgüllüğü %100 olarak bulundu. Sonuç: Sonuç olarak PFA-100 cihazı yüksek oranda özgül olmakla birlikte düşük oranda duyarlı bulunmuştur. Hafif tip-1 vWH için tarama testi olarak kullanılması sorun yaratabilir. von Willebrand hastalığının mutlak tanısı için spesifik testler (vWF:RCo, vWF:Ag) gerekmektedir. Ancak daha fazla hastayı içeren ileri çalışmalara ihtiyaç vardır.

  12. Comparison of inhibitory and binding characteristics of an antibody causing acquired von Willebrand syndrome: an assay for von Willebrand factor binding by antibody.

    PubMed

    Fricke, W A; Brinkhous, K M; Garris, J B; Roberts, H R

    1985-09-01

    An acquired inhibitor of von Willebrand factor (vWF) activity occurring in a patient with benign gammopathy and von Willebrand syndrome (vWS) has been partially characterized. The inhibitor-induced syndrome resulted in low to undetectable plasma levels of vWF/ristocetin, vWF/botrocetin, FVIIIR:Ag, and FVIII:C with a normal to slightly prolonged bleeding time. Platelet vWF was normal. Intensive and continuous infusion of a heat-treated factor VIII concentrate (Hemofil-T, Hyland, Glendale, Calif) elevated the FVIII:C plasma levels to about 100%, with an increase in FVIIIR:Ag levels to about 340% and vWF/ristocetin levels to about 40%, much lower than expected based on the dose of Hemofil-T and its content of vWF and FVIII:C activities. The inhibitor bound to staphylococcal protein A (SpA) with high affinity, indicating an IgG antibody (Ab). An assay for the vWF-binding capacity was developed on the basis of absorption of the Ab from serially diluted plasma by SpA and removal of vWF and FVIII:C activities from normal plasma by the SpA-Ab complex. The Ab-binding site was on the vWF component of the factor VIII complex. The Ab was unable to bind isolated FVIII:C. The combined use of the new vWF-binding assay and a battery of tests for inhibition of vWF-dependent platelet aggregation with ristocetin (which detects high molecular weight vWF), with botrocetin (which detects high and low molecular weight vWF), and with platelet-aggregating factor (which detects high molecular weight vWF) provided a means of analysis of Ab effect on in vitro vWF function. Using these tests, a comparison was made of the effects of the vWS Ab with those of an Ab inhibitor occurring in homozygous von Willebrand's disease. The Ab of the vWS patient had weak inhibitory action on vWF/ristocetin without having an effect on vWF/botrocetin and platelet-aggregating factor, a high titer vWF-binding capacity, and no anamnestic response following concentrate therapy. These findings contrasted with those

  13. Evaluation of a von Willebrand factor three test panel and chemiluminescent-based assay system for identification of, and therapy monitoring in, von Willebrand disease.

    PubMed

    Favaloro, Emmanuel J; Mohammed, Soma

    2016-05-01

    von Willebrand disease (VWD) is reportedly the most common bleeding disorder and arises from deficiency and/or defects of von Willebrand factor (VWF). Laboratory diagnosis and typing of VWD has important management implications and requires a wide range of tests, including VWF antigen (VWF:Ag) and various activities, involving differential identification of qualitative vs quantitative VWF defects. We have assessed a new hemostasis instrument, the chemiluminescent assay based ACL AcuStar™, and an associated HemosIL AcuStar three test panel comprising VWF:Ag, VWF ristocetin cofactor (VWF:RCo) and VWF collagen binding (VWF:CB) (Instrumentation Laboratory, Bedford, Ma. USA) for ability to identify VWD, to help provisionally type VWD, and for potential use in therapy monitoring. This test system was compared to previously evaluated and validated test systems including VWF:RCo on CS-5100 and BCS analyzers, the new Siemens INNOVANCE assay (VWF Ac) on CS-5100, and VWF:Ag and VWF:CB assays performed by automated ELISA. We employed a large total sample test set (n=535) comprising plasma and platelet-lysate samples from individuals with and without VWD, some on treatment, normal plasmas, and normal and pathological controls. We also evaluated desmopressin (DDAVP) responsiveness, plus differential sensitivity to reduction in high molecular weight (HMW) VWF. The chemiluminescent test panel (VWF:Ag, VWF:RCo, VWF:CB) showed good comparability to similar assays performed by alternate methods, and broadly similar data for identification of VWD, provisional VWD type identification, DDAVP and VWD therapy, and HMW VWF sensitivity, although some notable differences were evident. The chemiluminescent system showed best low level VWF sensitivity, and lowest inter-assay variability, compared to all other systems. In conclusion, we have validated theACL AcuStar and the chemiluminescent HemosIL AcuStar VWF test panel for use in VWD diagnostics, and have identified some favorable

  14. Interaction of blood platelets with a microfibrillar extract from adult bovine aorta: requirement for von Willebrand factor.

    PubMed Central

    Fauvel, F; Grant, M E; Legrand, Y J; Souchon, H; Tobelem, G; Jackson, D S; Caen, J P

    1983-01-01

    Adult bovine aortic tissue was treated with 6 M guanidinium chloride in the presence of proteinase inhibitors to obtain an extract that was essentially devoid of collagenous components and appeared homogeneous by electron microscopy. When this extract was dispersed by sonication it was found to be a very potent inducer of human platelet aggregation. This interaction required the presence of von Willebrand factor and of its receptor (glycoprotein Ib) on platelet membrane. This was demonstrated by the fact that the aggregation of normal blood platelets resuspended in plasmas deficient in von Willebrand factor was significantly diminished as compared to aggregation in control plasma. Moreover, this aggregation was inhibited by a monoclonal antibody, IgG AN51, to platelet glycoprotein Ib. These studies provide direct biochemical evidence for the existence of a thrombogenic constituent of the vessel wall that is noncollagenous and von Willebrand factor-dependent. Images PMID:6601274

  15. WARP is a new member of the von Willebrand factor A-domain superfamily of extracellular matrix proteins.

    PubMed

    Fitzgerald, Jamie; Tay Ting, Su; Bateman, John F

    2002-04-24

    We report a new member of the von Willebrand factor A-domain protein superfamily, WARP (for von Willebrand factor A-domain-related protein). The full-length mouse WARP cDNA is 2.3 kb in size and predicts a protein of 415 amino acids which contains a signal sequence, a VA-like domain, two fibronectin type III-like repeats, and a short proline- and arginine-rich segment. WARP mRNA was expressed predominantly in chondrocytes and in vitro expression experiments in transfected 293 cells indicated that WARP is a secreted glycoprotein that forms disulphide-bonded oligomers. We conclude that WARP is a new member of the von Willebrand factor A-domain (VA-domain) superfamily of extracellular matrix proteins which may play a role in cartilage structure and function.

  16. N-linked glycan truncation causes enhanced clearance of plasma-derived von Willebrand factor.

    PubMed

    O'Sullivan, J M; Aguila, S; McRae, E; Ward, S E; Rawley, O; Fallon, P G; Brophy, T M; Preston, R J S; Brady, L; Sheils, O; Chion, A; O'Donnell, J S

    2016-12-01

    Essentials von Willebrands factor (VWF) glycosylation plays a key role in modulating in vivo clearance. VWF glycoforms were used to examine the role of specific glycan moieties in regulating clearance. Reduction in sialylation resulted in enhanced VWF clearance through asialoglycoprotein receptor. Progressive VWF N-linked glycan trimming resulted in increased macrophage-mediated clearance. Click to hear Dr Denis discuss clearance of von Willebrand factor in a free presentation from the ISTH Academy SUMMARY: Background Enhanced von Willebrand factor (VWF) clearance is important in the etiology of both type 1 and type 2 von Willebrand disease (VWD). In addition, previous studies have demonstrated that VWF glycans play a key role in regulating in vivo clearance. However, the molecular mechanisms underlying VWF clearance remain poorly understood. Objective To define the molecular mechanisms through which VWF N-linked glycan structures influence in vivo clearance. Methods By use of a series of exoglycosidases, different plasma-derived VWF (pd-VWF) glycoforms were generated. In vivo clearance of these glycoforms was then assessed in VWF(-/-) mice in the presence or absence of inhibitors of asialoglycoprotein receptor (ASGPR), or following clodronate-induced macrophage depletion. Results Reduced amounts of N-linked and O-linked sialylation resulted in enhanced pd-VWF clearance modulated via ASGPR. In addition to this role of terminal sialylation, we further observed that progressive N-linked glycan trimming also resulted in markedly enhanced VWF clearance. Furthermore, these additional N-linked glycan effects on clearance were ASGPR-independent, and instead involved enhanced macrophage clearance that was mediated, at least in part, through LDL receptor-related protein 1. Conclusion The carbohydrate determinants expressed on VWF regulate susceptibility to proteolysis by ADAMTS-13. In addition, our findings now further demonstrate that non-sialic acid carbohydrate

  17. von Willebrand disease and other disorders of hemostasis in the patient with menorrhagia.

    PubMed

    Kouides, Peter A

    2005-09-01

    Separately, von Willebrand disease and menorrhagia are two relatively common conditions; in combination they occur at a prevalence of approximately 11-16%. Such patients exhibit a reduced quality of life and can incur a relatively high rate of gynecologic interventions; for example dilatation and curettage, endometrial ablation and hysterectomy. Initial evaluation involves a focused history for the following bleeding symptoms: menorrhagia since menarche, easy bruising of greater than 5 cm 1-2 times/month, frequent gum bleeding when flossing or brushing teeth or epistaxis 1-2 times/month. In addition, for those who have already undergone invasive interventions with the subsequent risk for hemorrhage, inquiry should be made regarding excessive bleeding with childbirth, dental tooth extraction and/or surgery. Step-wise testing includes a complete blood cell count and an assessment of the prothrombin time, activated partial thromboplastin time, iron profile, serum creatinine and thyroid-stimulating hormone level, followed by Factor VIII level, von Willebrand factor antigen and ristocetin cofactor, followed by consideration of platelet aggregation studies. Additional hemostatic studies may include obtaining a Factor XI level and euglobulin clot lysis time. Intuitively, failure to diagnose an underlying hemostatic disorder may lead to continued menorrhagia and diminished quality of life, as well as unnecessary surgical interventions that may in turn be fraught with an increased risk of bleeding. The management of von Willebrand disease-related menorrhagia involves consideration of the patient's age, childbearing status and preference. In the adolescent, surgical intervention is not an option, whereas an older patient beyond her childbearing years may choose a hysterectomy as a definitive treatment in lieu of continued medical therapy with intranasal/subcutaneous 1-deamino-8-D-arginine vasopressin (DDAVP), oral antifibrinolytic agents or oral contraceptive. The sexually

  18. Life-threatening bleeding in a patient with mild hemophilia A and heterozygosity for von Willebrand disease Type 2N.

    PubMed

    Allan, John N; Friedman, Kenneth D; DeSancho, Maria T

    2014-12-01

    Hemophilia A and von Willebrand disease (VWD) are distinct bleeding disorders with a spectrum of clinical phenotypes. They are characterized by mutations in either factor VIII (F8) or von Willebrand factor (VWF) genes, respectively. The pattern of inheritance and appropriate laboratory evaluation differentiates these diseases, and treatment strategies for both are different. Here, we report a male patient with hemophilia A and VWD Type 2 Normandy (N) mutations who presented with life-threatening bleeding. We document his medical history, clinical course, management, and diagnostic work up.

  19. N-linked glycans within the A2 domain of von Willebrand factor modulate macrophage-mediated clearance.

    PubMed

    Chion, Alain; O'Sullivan, Jamie M; Drakeford, Clive; Bergsson, Gudmundur; Dalton, Niall; Aguila, Sonia; Ward, Soracha; Fallon, Padraic G; Brophy, Teresa M; Preston, Roger J S; Brady, Lauren; Sheils, Orla; Laffan, Michael; McKinnon, Thomas A J; O'Donnell, James S

    2016-10-13

    Enhanced von Willebrand factor (VWF) clearance is important in the etiology of von Willebrand disease. However, the molecular mechanisms underlying VWF clearance remain poorly understood. In this study, we investigated the role of VWF domains and specific glycan moieties in regulating in vivo clearance. Our findings demonstrate that the A1 domain of VWF contains a receptor-recognition site that plays a key role in regulating the interaction of VWF with macrophages. In A1-A2-A3 and full-length VWF, this macrophage-binding site is cryptic but becomes exposed following exposure to shear or ristocetin. Previous studies have demonstrated that the N-linked glycans within the A2 domain play an important role in modulating susceptibility to ADAMTS13 proteolysis. We further demonstrate that these glycans presented at N1515 and N1574 also play a critical role in protecting VWF against macrophage binding and clearance. Indeed, loss of the N-glycan at N1515 resulted in markedly enhanced VWF clearance that was significantly faster than that observed with any previously described VWF mutations. In addition, A1-A2-A3 fragments containing the N1515Q or N1574Q substitutions also demonstrated significantly enhanced clearance. Importantly, clodronate-induced macrophage depletion significantly attenuated the increased clearance observed with N1515Q and N1574Q in both full-length VWF and A1-A2-A3. Finally, we further demonstrate that loss of these N-linked glycans does not enhance clearance in VWF in the presence of a structurally constrained A2 domain. Collectively, these novel findings support the hypothesis that conformation of the VWF A domains plays a critical role in modulating macrophage-mediated clearance of VWF in vivo.

  20. Low von Willebrand factor: sometimes a risk factor and sometimes a disease.

    PubMed

    Sadler, J Evan

    2009-01-01

    A sufficiently low level of von Willebrand factor (VWF) predisposes to bleeding that can be quite serious, and low VWF is a diagnostic feature of von Willebrand disease (VWD) type 1, which is characterized by partial quantitative deficiency of VWF. Recent groundbreaking studies of patients with VWD type 1 have delineated several pathophysiologic mechanisms that determine the plasma concentration of VWF, but the relationship between VWF level and the likelihood of bleeding remains less well understood. In part, this problem reflects the broad range of VWF levels in the population, so that the distinction between "normal" and "low" is arbitrary. The risk of bleeding certainly increases as the VWF level decreases, but the relationship is not very strong until the VWF level is very low. Furthermore, mild bleeding symptoms are common in apparently healthy populations and have many causes other than defects in VWF, which can make it impossible to attribute bleeding to any single factor, such as low VWF. These difficulties might be resolved by an epidemiologic approach to VWF and other risk factors for bleeding, analogous to how physicians manage multiple risk factors for cardiovascular disease or venous thromboembolism.

  1. Synthesis by guinea pig megakaryocytes of platelet glycoprotein receptors for fibrinogen and von Willebrand factor.

    PubMed

    Kupinski, J M; Miller, J L

    1986-08-01

    In the preceding paper, we described two monoclonal antibodies, PG-1 and PG-2, that selectively blocked the binding of von Willebrand factor (PG-1) or of fibrinogen (PG-2) to guinea pig platelets. In this study we examine the structures and site of synthesis of these receptors. NP-40 lysates of radiolabeled guinea pig platelets were immunoprecipitated with monoclonal antibodies PG-1 or PG-2, and the precipitates analyzed by SDS-PAGE. PG-1 recognized a single polypeptide with reduced Mr of 143,000 daltons, while PG-2 precipitated two chains with reduced Mr of 121,000 and 93,000 daltons. Periodate-[3H]borohydride labeling of platelets, in conjunction with two-dimensional SDS-PAGE, showed that all three of the polypeptides are glycoproteins and that the 143,000 and 121,000 dalton chains are linked by disulfide bond(s) to smaller, approximately 25,000 dalton polypeptides. Guinea pig megakaryocytes synthesized polypeptides immunoprecipitable by PG-1 and PG-2, with molecular weights similar to polypeptides found associated with platelet membranes. These studies demonstrate that guinea pig platelets have functional receptors for fibrinogen and von Willebrand factor that are structurally homologous to human platelet glycoproteins Ib, IIb and IIIa, and that these glycoproteins are synthesized by megakaryocytes.

  2. Impaired megakaryocytopoiesis in type 2B von Willebrand disease with severe thrombocytopenia.

    PubMed

    Nurden, Paquita; Debili, Najet; Vainchenker, William; Bobe, Regis; Bredoux, Raymonde; Corvazier, Elisabeth; Combrie, Robert; Fressinaud, Edith; Meyer, Dominique; Nurden, Alan T; Enouf, Jocelyne

    2006-10-15

    In type 2B von Willebrand disease, there is spontaneous binding of mutated von Willebrand factor (VWF) multimers to platelets. Here we report a family in which severe thrombocytopenia may also be linked to abnormal megakaryocytopoiesis. A heterozygous mutation in the VWF A1 domain gave a R1308P substitution in an interactive site for glycoprotein Ibalpha (GPIbalpha). Electron microscopy showed clusters of platelets in close contact. Binding of antibodies to the GPIbalpha N-terminal domain was decreased, whereas GPIX and GPV were normally detected. In Western blotting (WB), GPIbalpha, alphaIIb, and beta3 were normally present. Proteins involved in Ca(2+) homeostasis were analyzed by quantitating platelet mRNA or by WB. Plasma membrane Ca(2+) ATPase (PMCA)-4b and type III inositol trisphosphate receptor (InsP(3)-R3) were selectively increased. The presence of degradation products of polyadenosine diphosphate (ADP)-ribose polymerase protein (PARP) suggested ongoing caspase-3 activity. These were findings typical of immature normal megakaryocytes cultured from peripheral blood CD34(+) cells with TPO. Significantly, megakaryocytes from the patients in culture produced self-associated and interwoven proplatelets. Immunolocalization showed VWF not only associated with platelets, but already on the megakaryocyte surface and within internal channels. In this family, type 2B VWD is clearly associated with abnormal platelet production.

  3. Rapid high-resolution electrophoresis of multimeric von Willebrand Factor using a thermopiloted gel apparatus.

    PubMed

    Smejkal, Gary B; Shainoff, John R; Kottke-Marchant, Kandice M

    2003-02-01

    Rapid and highly reproducible nonreducing agarose gel electrophoresis (NRAGE) of von Willebrand Factor (vWF) multimers was performed using a thermostated minigel apparatus that monitors and precisely controls internal gel temperature. The substitution of lithium dodecyl sulfate (LiDS) for sodium dodecyl sulfate (SDS) allowed electrophoresis to be performed below the 16 degrees C Krafft point of SDS and facilitated NRAGE of vWF over the entire range of 0-35 degrees C. Internal gel temperature was regulated by a thermocouple probe inserted directly into the gel during electrophoresis which interfaced with a thermopilot that continually measures and adjusts temperature to within +/- 0.5 degrees C. At 10 degrees C operative temperature, NRAGE at 1.5% agarose concentration was completed in 20 min at 250 V. Electrophoresis could be performed in only 10 min at 500 V, but at such high voltages, localized temperature fluctuations as much as 6 degrees C resulted in perturbation of banding patterns in those vicinities. In the optimized method, both high molecular weight multimers and proteolytic fragments of vWF were separable suggesting clinical applicability of this system for the diagnosis of von Willebrand Disease and thrombotic thrombocytopenic purpura.

  4. Mutational Constraints on Local Unfolding Inhibit the Rheological Adaptation of von Willebrand Factor*

    PubMed Central

    Tischer, Alexander; Campbell, James C.; Machha, Venkata R.; Moon-Tasson, Laurie; Benson, Linda M.; Sankaran, Banumathi; Kim, Choel; Auton, Matthew

    2016-01-01

    Unusually large von Willebrand factor (VWF), the first responder to vascular injury in primary hemostasis, is designed to capture platelets under the high shear stress of rheological blood flow. In type 2M von Willebrand disease, two rare mutations (G1324A and G1324S) within the platelet GPIbα binding interface of the VWF A1 domain impair the hemostatic function of VWF. We investigate structural and conformational effects of these mutations on the A1 domain's efficacy to bind collagen and adhere platelets under shear flow. These mutations enhance the thermodynamic stability, reduce the rate of unfolding, and enhance the A1 domain's resistance to limited proteolysis. Collagen binding affinity is not significantly affected indicating that the primary stabilizing effect of these mutations is to diminish the platelet binding efficiency under shear flow. The enhanced stability stems from the steric consequences of adding a side chain (G1324A) and additionally a hydrogen bond (G1324S) to His1322 across the β2-β3 hairpin in the GPIbα binding interface, which restrains the conformational degrees of freedom and the overall flexibility of the native state. These studies reveal a novel rheological strategy in which the incorporation of a single glycine within the GPIbα binding interface of normal VWF enhances the probability of local unfolding that enables the A1 domain to conformationally adapt to shear flow while maintaining its overall native structure. PMID:26677223

  5. Expression of von Willebrand factor Normandy: An autosomal mutation that mimics hemophilia A

    SciTech Connect

    Tuley, E.A.; Worrall, N.K.; Sadler, J.E. ); Gaucher, C.; Jorieux, S.; Mazurier, C. )

    1991-07-15

    von Willebrand disease Normandy (vWD Normandy) is a recently described phenotype in which a mutant von Willebrand factor (VWF) appears structurally and functionally normal except that is does not bind to blood coagulation factor VIII. This interaction is required for normal survival of factor VIII in the circulation; consequently, vWD Normandy can present as apparent hemophilia A but with autosomal recessive rather than X chromosome-linked inheritance. AvWF missense mutation, Thr{sup 28} {r arrow} Met, was identified in the propositus in or near the factor VIII binding site. The corresponding mutant recombinant vWF(T28M) formed normal multimers and had normal ristocetin cofactor activity. However, vWF(T28M) exhibited the same defect in factor VIII binding as natural vWF Normandy, confirming that this mutation causes the vWD Normandy phenotype. The distinction between hemophilia A and vWD Normandy is clinically important and should be considered in families affected by apparent mild hemophilia A that fail to show strict X chromosome-linked inheritance and, particularly, in potential female carriers with low factor VIII levels attributed to extreme lyonization.

  6. Evidence-based diagnosis of type 1 von Willebrand disease: a Bayes theorem approach.

    PubMed

    Tosetto, Alberto; Castaman, Giancarlo; Rodeghiero, Francesco

    2008-04-15

    The diagnosis of type 1 von Willebrand disease (VWD) is based on the presence of bleeding symptoms, reduced von Willebrand factor (VWF) levels, and autosomal inheritance of the phenotype. To better appreciate the contribution of clinical and laboratory data to the final diagnosis of VWD, we computed the likelihoods of having VWD as a function of the bleeding score (LR(score)), of VWF level (LR(VWF)), and of number of first-degree family members with reduced VWF levels (LR(family)). The 3 likelihoods were therefore combined using the Bayes theorem, giving the final probability (odds) of having VWD. LR(family) and LR(VWF) were the 2 factors mostly influencing the final probability of having VWD. Data from the present study provide an evidence-based description of the minimal criteria for the diagnosis of type 1 VWD. As an example, presence of VWF levels lower than 40 IU/dL in at least 2 family members (including the proband) and a bleeding score of at least 1 were found to be required for a final odd of VWD higher than 2.0 (false-positive rate less than one-half). Validation of this approach and of its clinical utility is, however, required by analysis in other cohorts of well-characterized type 1 VWD patients.

  7. Misfolding of vWF to Pathologically Disordered Conformations Impacts the Severity of von Willebrand Disease

    PubMed Central

    Tischer, Alexander; Madde, Pranathi; Moon-Tasson, Laurie; Auton, Matthew

    2014-01-01

    The primary hemostatic von Willebrand factor (vWF) functions to sequester platelets from rheological blood flow and mediates their adhesion to damaged subendothelium at sites of vascular injury. We have surveyed the effect of 16 disease-causing mutations identified in patients diagnosed with the bleeding diathesis disorder, von Willebrand disease (vWD), on the structure and rheology of vWF A1 domain adhesiveness to the platelet GPIbα receptor. These mutations have a dynamic phenotypical range of bleeding from lack of platelet adhesion to severe thrombocytopenia. Using new rheological tools in combination with classical thermodynamic, biophysical, and spectroscopic metrics, we establish a high propensity of the A1 domain to misfold to pathological molten globule conformations that differentially alter the strength of platelet adhesion under shear flow. Rheodynamic analysis establishes a quantitative rank order between shear-rate-dependent platelet-translocation pause times that linearly correlate with clinically reported measures of patient platelet counts and the severity of thrombocytopenia. These results suggest that specific secondary structure elements remaining in these pathological conformations of the A1 domain regulate GPIbα binding and the strength of vWF-platelet interactions, which affects the vWD functional phenotype and the severity of thrombocytopenia. PMID:25185554

  8. Similarity in Joint Function Limitation in Type 3 Von Willebrand Disease and Moderate Haemophilia A

    PubMed Central

    Sood, S.L.; Cuker, A.; Wang, C.; Metjian, A.D.; Chiang, E.Y.; Soucie, J.M.; Konkle, B.A.

    2013-01-01

    Introduction Type 3 von Willebrand Disease (VWD) is a rare bleeding diathesis with complete or near complete deficiency of von Willebrand factor (VWF) and low factor VIII (FVIII) levels. In contrast, only FVIII is decreased in haemophilia A (HA). Both disorders are complicated by arthropathy. Aim The purpose of this study was to further clarify the roles of FVIII and VWF: Antigen (VWF:Ag) in joint range of motion (ROM) loss over time. Methods We compared joint ROM loss and other bleeding manifestations in 100 Type 3 VWD subjects (FVIII≤5%) and 1814 moderate HA subjects (FVIII 1–5%) within the U.S. Universal Data Collection (UDC) database. Results High rates of bleeding were reported at baseline. During follow up, moderate HA patients reported a joint (46% vs. 34%, p<0.0001) or muscle bleed (27% vs. 16%, p< 0.0001) in a higher proportion of visits than VWD patients. Other bleeds, including mucosal, were reported in a greater proportion of visits among patients with Type 3 VWD than among those with HA (49% vs. 32%, p<0.0001). Multivariate analysis revealed no difference in joint ROM loss over time in the Type 3 VWD versus moderate HA populations. A higher FVIII level was protective in both VWD and HA (p<0.001). Conclusion Our findings support the hypothesis of primacy of the FVIII level in determining risk of joint hemorrhage, and may help target therapy in Type 3 VWD and moderate HA to prevent joint disability. PMID:23534856

  9. Tissue factor: A potent stimulator of Von Willebrand factor synthesis by human umbilical vein endothelial cells

    PubMed Central

    Meiring, Muriel; Allers, W.; Le Roux, E.

    2016-01-01

    Inflammation and dysfunction of endothelial cells are thought to be triggers for the secretion of Von Willebrand factor. The aim of this study was to examine the effects of the inflammatory cytokines interleukin-6 (IL-6), interleukin-8 (IL-8) and tumour necrosis factor-alpha (TNF-α) and the coagulation factors, tissue factor and thrombin on the release and cleavage potential of ultra-large von Willebrand factor (ULVWF) and its cleavage protease by cultured human umbilical vein endothelial cells (HUVEC). HUVEC were treated with IL-6, IL-8, and TNF-α, tissue factor (TF) and thrombin, and combinations thereof for 24 hours under static conditions. The cells were then exposed to shear stress after which the VWF-propeptide levels and the VWF cleavage protease, ADAMTS13 content were measured. All treatments and their combinations, excluding IL-6, significantly stimulated the secretion of VWF from HUVEC. The VWF secretion from the HUVEC was stimulated most by the combination of TF with TNF-α. Slightly lower levels of ADAMTS13 secretion were found with all treatments. This may explain the thrombogenicity of patients with inflammation where extremely high VWF levels and slightly lower ADAMTS13 levels are present. PMID:27766025

  10. Towards personalised therapy for von Willebrand disease: a future role for recombinant products

    PubMed Central

    Favaloro, Emmanuel J.

    2016-01-01

    von Willebrand disease (VWD) is reportedly the most common bleeding disorder and is caused by deficiencies and/or defects in the adhesive plasma protein von Willebrand factor (VWF). Functionally, normal VWF prevents bleeding by promoting both primary and secondary haemostasis. In respect to primary haemostasis, VWF binds to both platelets and sub-endothelial matrix components, especially collagen, to anchor platelets to damaged vascular tissue and promote thrombus formation. VWF also stabilises and protects factor VIII in the circulation, delivering FVIII to the site of injury, which then facilitates secondary haemostasis and fibrin formation/thrombus stabilisation. As a result of this, patients with VWD suffer a bleeding diathesis reflective of a primary defect caused by defective/deficient VWF, which in some patients is compounded by a reduction in FVIII. Management of VWD, therefore, chiefly entails replacement of VWF, and sometimes also FVIII, to protect against bleeding. The current report principally focuses on the future potential for “personalised” management of VWD, given the emerging options in recombinant therapies. Recombinant VWF has been developed and is undergoing clinical trials, and this promising therapy may soon change the way in which VWD is managed. In particular, we can envisage a personalised treatment approach using recombinant VWF, with or without recombinant FVIII, depending on the type of VWD, the extent of deficiencies, and the period and duration of treatment. PMID:27136426

  11. Type 2B von Willebrand Disease: A Matter of Plasma Plus Platelet Abnormality.

    PubMed

    Castaman, Giancarlo; Federici, Augusto B

    2016-07-01

    Type 2B von Willebrand disease (VWD2B) is a rare, autosomal-dominant inherited bleeding disorder, characterized by an enhanced ristocetin-induced platelet aggregation in platelet-rich plasma and often with variable degree of thrombocytopenia and loss of high-molecular-weight multimers von Willebrand factor (VWF). All these phenomena are caused by a mutant VWF, normally synthesized and assembled by endothelial cells, but with heightened affinity binding to the platelet receptor glycoprotein Ib-α (GpIb-α). When this abnormal VWF is released into the circulation and under specific clinical circumstances, in vivo platelet clumping is observed. Mutations, invariably clustered in exon 28 of the VWF gene encoding for the VWF A1 domain involved in VWF binding to GpIb-α, are responsible for VWD2B phenotype. Clinical and laboratory phenotype appears strongly related to the type of VWF-causative mutations. However, recent evidences suggest that a true platelet defect is also present in this type, with several morphological and functional abnormalities being detected in a subset of VWD2B patients.

  12. Cellular and molecular basis of von Willebrand disease: studies on blood outgrowth endothelial cells.

    PubMed

    Starke, Richard D; Paschalaki, Koralia E; Dyer, Clare E F; Harrison-Lavoie, Kimberly J; Cutler, Jacqueline A; McKinnon, Thomas A J; Millar, Carolyn M; Cutler, Daniel F; Laffan, Mike A; Randi, Anna M

    2013-04-04

    Von Willebrand disease (VWD) is a heterogeneous bleeding disorder caused by decrease or dysfunction of von Willebrand factor (VWF). A wide range of mutations in the VWF gene have been characterized; however, their cellular consequences are still poorly understood. Here we have used a recently developed approach to study the molecular and cellular basis of VWD. We isolated blood outgrowth endothelial cells (BOECs) from peripheral blood of 4 type 1 VWD and 4 type 2 VWD patients and 9 healthy controls. We confirmed the endothelial lineage of BOECs, then measured VWF messenger RNA (mRNA) and protein levels (before and after stimulation) and VWF multimers. Decreased mRNA levels were predictive of plasma VWF levels in type 1 VWD, confirming a defect in VWF synthesis. However, BOECs from this group of patients also showed defects in processing, storage, and/or secretion of VWF. Levels of VWF mRNA and protein were normal in BOECs from 3 type 2 VWD patients, supporting the dysfunctional VWF model. However, 1 type 2M patient showed decreased VWF synthesis and storage, indicating a complex cellular defect. These results demonstrate for the first time that isolation of endothelial cells from VWD patients provides novel insight into cellular mechanisms of the disease.

  13. Laboratory aspects of von Willebrand disease: test repertoire and options for activity assays and genetic analysis.

    PubMed

    Castaman, G; Hillarp, A; Goodeve, A

    2014-05-01

    The deficiency or abnormal function of von Willebrand factor (VWF) causes von Willebrand disease (VWD), the most frequent inherited bleeding disorder. The laboratory diagnosis of VWD can be difficult as the disease is heterogeneous and an array of assays is required to describe the phenotype. Basic classification of quantitative (type 1 and 3) and qualitative (type 2) VWD variants requires determination of VWF antigenic (VWF:Ag) levels and assaying of VWF ristocetin cofactor (VWF:RCo) activity, determining the capacity of VWF to interact with the platelet GPIb-receptor. Knowing the VWF:RCo activity is essential for identifying, subtyping and monitoring VWD, but the assay is poorly standardized and many protocols do not fulfil the clinical need in all situations. This has led to the development of novel activity assays, independent of ristocetin, with enhanced assay characteristics. Results from the first independent clinical evaluations are promising, showing that they are reliable and suitable for VWD diagnosis. The qualitative type 2 VWF deficiency can be further divided into four different subtypes (A, B, M and N) using specific assays that explore other activities or the size distribution of VWF multimers. These methods are discussed herein. However, in a number of patients it may be difficult to correctly classify the VWD phenotype and genetic analysis may provide the best option to clarify the disorder, through mutation identification.

  14. Wilate use in 47 children with von Willebrand disease: the North London paediatric haemophilia network experience.

    PubMed

    Khair, K; Batty, P; Riat, R; Bowles, L; Burgess, C; Chen, Y-H; Hart, D; Platton, S; Pasi, J; Liesner, R

    2015-01-01

    Children with von Willebrand disease (VWD) in whom DDAVP is ineffective or contraindicated require treatment with a coagulation factor concentrate containing von Willebrand factor (VWF) and factor VIII (FVIII). The aim of this study was to monitor the safety, efficacy and tolerability of Wilate(®) (a VWF:FVIII concentrate with a 1:1 ratio) used across the North London Paediatric Haemophilia Network since May 2010. In total, 47 children (aged 0.0-17.0 years) with type 1 (n = 28), type 2 (n = 7), type 3 (n = 10) and acquired VWS (n = 2) have been treated for bleeds, surgery and/or prophylaxis using 260 000 IU Wilate(®). Analysis of dose and frequency of treatment show expected responses to treatment with mean doses of 55, 50 and 50 IU kg(-1) for bleeds, surgery and prophylaxis respectively. Most bleeds responded to a single treatment. Surgical procedures were covered with clinician approved dosing schedules with 95% (39/41) reported as having excellent or good efficacy. There was no accumulation of FVIII or VWF and no thromboembolic events. This case series confirms the efficacy, safety and tolerability of Wilate(®) in neonates, children and adolescents when used on-demand, prophylactically and in the surgical setting.

  15. The bleeding score predicts clinical outcomes and replacement therapy in adults with von Willebrand disease.

    PubMed

    Federici, Augusto B; Bucciarelli, Paolo; Castaman, Giancarlo; Mazzucconi, Maria G; Morfini, Massimo; Rocino, Angiola; Schiavoni, Mario; Peyvandi, Flora; Rodeghiero, Francesco; Mannucci, Pier Mannuccio

    2014-06-26

    Analyses of the bleeding tendency by means of the bleeding score (BS) have been proposed until now to confirm diagnosis but not to predict clinical outcomes in patients with inherited von Willebrand disease (VWD). We prospectively followed up, for 1 year, 796 Italian patients with different types of VWD to determine whether the previous BS of European VWD1 is useful to predict the occurrence of spontaneous bleeds severe enough to require replacement therapy with desmopressin (DDAVP) and/or von Willebrand factor (VWF)/factor VIII concentrates. Among the 796 patients included, 75 (9.4%) needed treatment of 232 spontaneous bleeding events. BS >10 and VWF:ristocetin cofactor activity <10 U/dL were associated with the risk of bleeding, but only a BS >10 remained highly associated in a multivariable Cox proportional hazard model (adjusted hazard ratio: 7.27 [95% confidence interval, 3.83-13.83]). Although the bleeding event-free survival was different in VWD types, only a BS >10 could predict for each type which patient had bleeding events severe enough to require treatment with DDAVP and/or concentrates. Therefore, BS can be considered a simple predictor of clinical outcomes of VWD and may identify patients needing intensive therapeutic regimens.

  16. Von Willebrand Disease and Pregnancy: A Review of Evidence and Expert Opinion.

    PubMed

    Reynen, Emily; James, Paula

    2016-10-01

    von Willebrand disease (VWD) is a common, inherited bleeding disorder. There are three main types of VWD, which result in a quantitative or qualitative deficiency in von Willebrand factor (VWF) and in severe cases, also Factor VIII (FVIII). The severity of bleeding depends on the underlying pathophysiology. Type 1 VWD is usually mild, while types 2 or 3 VWD can be associated with moderate or significant bleeding. Managing pregnant women with VWD requires a multidisciplinary approach. Such patients are at increased risk of postpartum hemorrhage. Whether women with VWD are at increased risk of spontaneous abortion remains unclear. Because of increased risk of bleeding, there are special considerations for delivery and obstetrical analgesia. There is a lack of high-quality evidence supporting monitoring and treatment of VWD in pregnancy. Most experts recommend that FVIII and VWF levels be monitored prior to delivery and treatment initiated when levels remain below 0.50 IU/mL. Some experts consider desmopressin (DDAVP) to be the preferred initial treatment in type 1 and most type 2 VWD. DDAVP is relatively contraindicated in type 2B disease. Plasma-derived FVIII and VWF replacements are the treatment of choice in type 2B and 3 VWD and in type 1 or 2 VWD when patients do not respond to DDAVP.

  17. [Obstetric analgesia and anesthesia with remifentanyl in a patient with von Willebrand disease].

    PubMed

    Novoa, L; Navarro Egea, M; Vieito Amor, M; Hernández Iniesta, J; Arxer, A; Villalonga, A

    2003-05-01

    A 30-year-old woman with von Willebrand's disease was admitted in labor. As epidural analgesia was ruled out due to risk of spinal hematoma, a pump for patient-controlled analgesia (PCA) was provided with boluses of remifentanil and set for intravenous infusion of 24 micrograms with a lockout time of 5 minutes. The patient reported analgesia to be satisfactory. Later, because of abnormal fetal positioning, an emergency cesarean was performed with the patient under general anesthesia with remifentanil, with propofol and succinylcholine for induction. A healthy girl was born free of respiratory depression. Von Willebrand's disease is a hemorrhagic disorder of autosomal dominant inheritance due to a quantitative or functional factor VIII deficit. Various subtypes and degrees of severity of abnormal bleeding have been described. It is the most common genetic hemostatic disorder affecting obstetric procedures, and although epidural analgesia has been used with strict hematologic monitoring, that technique carries a risk of hematoma. PCA is useful in patients for whom regional techniques are contraindicated. With adequate fetal and maternal monitoring, remifentanil in PCA is safe and more effective than other opiates for labor pain.

  18. Structural Basis of Regulation of von Willebrand Factor Binding to Glycoprotein Ib*

    PubMed Central

    Blenner, Mark A.; Dong, Xianchi; Springer, Timothy A.

    2014-01-01

    Activation by elongational flow of von Willebrand factor (VWF) is critical for primary hemostasis. Mutations causing type 2B von Willebrand disease (VWD), platelet-type VWD (PT-VWD), and tensile force each increase affinity of the VWF A1 domain and platelet glycoprotein Ibα (GPIbα) for one another; however, the structural basis for these observations remains elusive. Directed evolution was used to discover a further gain-of-function mutation in A1 that shifts the long range disulfide bond by one residue. We solved multiple crystal structures of this mutant A1 and A1 containing two VWD mutations complexed with GPIbα containing two PT-VWD mutations. We observed a gained interaction between A1 and the central leucine-rich repeats (LRRs) of GPIbα, previously shown to be important at high shear stress, and verified its importance mutationally. These findings suggest that structural changes, including central GPIbα LRR-A1 contact, contribute to VWF affinity regulation. Among the mutant complexes, variation in contacts and poor complementarity between the GPIbα β-finger and the region of A1 harboring VWD mutations lead us to hypothesize that the structures are on a pathway to, but have not yet reached, a force-induced super high affinity state. PMID:24391089

  19. Acquired von Willebrand's disease associated with epithelial myoepithelial carcinoma of the parotid salivary gland

    PubMed Central

    Chilvers, Geoffrey Spencer; Porter, Graham

    2014-01-01

    This is the first case report of a patient with acquired von Willebrand's disease (AvWD) secondary to epithelial myoepithelial carcinoma (EMC) of the parotid salivary gland. This patient presented to haematology following an abnormal bleeding episode with von Willebrand factor Ristocetin cofactor (VWF:RCo) <5% and VWF:Ag 13%. He was diagnosed with AvWD. At the same time he was found to have a left parotid lump which was excised following a multidisciplinary team meeting. This was histologically reported as an EMC. Following excision, unusually this patient's AvWD did not resolve. Extensive investigation looking for other causes of the AvWD did not reveal any other potential cause; therefore, due to the similar timing of onset of both pathologies it is felt that the AvWD in this case is secondary to the EMC. This case report highlights the presentation, investigation and management of AvWD and parotid lumps as well as discussing proposed pathophysiological mechanisms for AvWD. PMID:25096657

  20. Evidence-based recommendations on the treatment of von Willebrand disease in Italy

    PubMed Central

    Mannucci, Pier Mannuccio; Franchini, Massimo; Castaman, Giancarlo; Federici, Augusto B.

    2009-01-01

    Background von Willebrand disease (VWD) is the most common hereditary bleeding disorder affecting both males and females. It arises from quantitative or qualitative defects of von Willebrand factor (VWF) and causes bleeding of mucous membranes and soft tissues. The aim of treatment is to correct the dual defect of haemostasis caused by the abnormal/reduced VWF and the concomitant deficiency of factor VIII (FVIII). Material and methods This document contains evidence-based recommendations for the management of VWD compiled by AICE (the Italian Association of Haemophilia Centres). All the evidence supporting these recommendations are based on non-randomised comparative studies or case series, because randomised controlled clinical trials or meta-analyses are not available for this disease. Results and conclusions Desmopressin (DDAVP) is the treatment of choice for patients with type 1 VWD with FVIII and VWF levels of 10 U/dL or more, while VWF/FVIII concentrates are indicated for those who are unresponsive or insufficiently responsive to DDAVP (severe type 1, type 2 and 3 VWD). VWF concentrates devoid of FVIII, not yet licensed in Italy, may be considered for short-term prophylaxis in elective surgery or for long-term secondary prophylaxis. PMID:19503633

  1. Effect of Genetic Variation in STXBP5 and STX2 on von Willebrand Factor and Bleeding Phenotype in Type 1 von Willebrand Disease Patients

    PubMed Central

    van Loon, Janine E.; Sanders, Yvonne V.; de Wee, Eva M.; Kruip, Marieke J. H. A.; de Maat, Moniek P. M.; Leebeek, Frank W. G.

    2012-01-01

    Background In type 1 von Willebrand Disease (VWD) patients, von Willebrand Factor (VWF) levels and bleeding symptoms are highly variable. Recently, the association between genetic variations in STXBP5 and STX2 with VWF levels has been discovered in the general population. We assessed the relationship between genetic variations in STXBP5 and STX2, VWF levels, and bleeding phenotype in type 1 VWD patients. Methods In 158 patients diagnosed with type 1 VWD according to the current ISTH guidelines, we genotyped three tagging-SNPs in STXBP5 and STX2 and analyzed their relationship with VWF:Ag levels and the severity of the bleeding phenotype, as assessed by the Tosetto bleeding score. Results In STX2, rs7978987 was significantly associated with VWF:Ag levels (bèta-coefficient (β) = −0.04 IU/mL per allele, [95%CI −0.07;−0.001], p = 0.04) and VWF:CB activity (β = −0.12 IU/mL per allele, [95%CI −0.17;−0.06], p<0.0001). For rs1039084 in STXBP5 a similar trend with VWF:Ag levels was observed: (β = −0.03 IU/mL per allele [95% CI −0.06;0.003], p = 0.07). In women, homozygous carriers of the minor alleles of both SNPs in STXBP5 had a significantly higher bleeding score than homozygous carriers of the major alleles. (Rs1039084 p = 0.01 and rs9399599 p = 0.02). Conclusions Genetic variation in STX2 is associated with VWF:Ag levels in patients diagnosed with type 1 VWD. In addition, genetic variation in STXBP5 is associated with bleeding phenotype in female VWD patients. Our findings may partly explain the variable VWF levels and bleeding phenotype in type 1 VWD patients. PMID:22792389

  2. Platelet dysfunction and a high bone mass phenotype in a murine model of platelet-type von Willebrand disease.

    PubMed

    Suva, Larry J; Hartman, Eric; Dilley, Joshua D; Russell, Susan; Akel, Nisreen S; Skinner, Robert A; Hogue, William R; Budde, Ulrich; Varughese, Kottayil I; Kanaji, Taisuke; Ware, Jerry

    2008-02-01

    The platelet glycoprotein Ib-IX receptor binds surface-bound von Willebrand factor and supports platelet adhesion to damaged vascular surfaces. A limited number of mutations within the glycoprotein Ib-IX complex have been described that permit a structurally altered receptor to interact with soluble von Willebrand factor, and this is the molecular basis of platelet-type von Willebrand disease. We have developed and characterized a mouse model of platelet-type von Willebrand disease (G233V) and have confirmed a platelet phenotype mimicking the human disorder. The mice have a dramatic increase in splenic megakaryocytes and splenomegaly. Recent studies have demonstrated that hematopoetic cells can influence the differentiation of osteogenic cells. Thus, we examined the skeletal phenotype of mice expressing the G233V variant complex. At 6 months of age, G233V mice exhibit a high bone mass phenotype with an approximate doubling of trabecular bone volume in both the tibia and femur. Serum measures of bone resorption were significantly decreased in G233V animals. With decreased bone resorption, cortical thickness was increased, medullary area decreased, and consequently, the mechanical strength of the femur was significantly increased. Using ex vivo bone marrow cultures, osteoclast-specific staining in the G233V mutant marrow was diminished, whereas osteoblastogenesis was unaffected. These studies provide new insights into the relationship between the regulation of megakaryocytopoiesis and bone mass.

  3. Von Willebrand factor in patients on mechanical circulatory support - a double-edged sword between bleeding and thrombosis.

    PubMed

    Hudzik, Bartosz; Kaczmarski, Jacek; Pacholewicz, Jerzy; Zakliczynski, Michal; Gasior, Mariusz; Zembala, Marian

    2015-09-01

    Mechanical circulatory support (MCS) is an umbrella term describing the various technologies used in both short- and long-term management of patients with either end-stage chronic heart failure (HF) or acute HF. Most often, MCS has emerged as a bridge to transplantation, but more recently it is also used as a destination therapy. Mechanical circulatory support includes left ventricular assist device (LVAD) or bi-ventricular assist device (Bi-VAD). Currently, 2- to 3-year survival in carefully selected patients is much better than with medical therapy. However, MCS therapy is hampered by sometimes life-threatening complications including bleeding and device thrombosis. Von Willebrand factor (vWF) has two major functions in haemostasis. First, it plays a crucial role in platelet-subendothelium adhesion and platelet-platelet interactions (aggregation). Second, it is the carrier of factor VIII (FVIII) in plasma. Von Willebrand factor prolongs FVIII half-time by protecting it from proteolytic degradation. It delivers FVIII to the site of vascular injury thus enhancing haemostatic process. On one hand, high plasma levels of vWF have been associated with an increased risk of thrombosis. On the other, defects or deficiencies of vWF underlie the inherited von Willebrand disease or acquired von Willebrand syndrome. Here we review the pathophysiology of thrombosis and bleeding associated with vWF.

  4. Comprehensive evaluation of haemostatic function in von Willebrand disease patients using a microchip-based flow chamber system.

    PubMed

    Ogiwara, K; Nogami, K; Hosokawa, K; Ohnishi, T; Matsumoto, T; Shima, M

    2015-01-01

    The diagnosis of von Willebrand disease (VWD) is difficult due to the wide spectrum of clinical phenotypes associated with this disorder. We have analysed and characterized haemostatic function in VWD patients using a microchip-based flow chamber system. Microchips coated with either collagen [platelet (PL)-chip] or collagen/thromboplastin [atherome (AR)-chip] were used to evaluate platelet thrombus formation at 1000 s(-1) and fibrin-rich platelet thrombus formation at 240 s(-1) respectively. Blood samples from an asymptomatic patient with VWD type 1 [von Willebrand factor (VWF): RCo 3.2%; bleeding score (BS 2] displayed normal thrombus formation in both PL- and AR-chips, whereas blood from a symptomatic type 1 patient (VWF: RCo 14%, BS 9) had significantly delayed capillary occlusion. Nearly complete suppression of the flow pressure increase was observed in symptomatic patients with VWD type 2A (BS 13) and 2N (BS 27), whereas no flow pressure was found for the type 3 patient (BS 6). Fibrin-rich platelet thrombus formation was only weakly increased by the in vitro addition of factor VIII (FVIII) to blood samples from the type 3 patient, but was normalized by the addition of VWF/FVIII. The in vivo effects of treatment with desmopressin or VWF/FVIII for the symptomatic patients were analysed using two types of microchips. The PL-chip was highly sensitive for patients' VWF-mediated platelet functions, whereas the AR-chip allowed assessment of overall haemostatic ability, including sensitivity to both VWF and FVIII. The combined analysis with PL- and AR-chips may be potentially useful for the diagnosis of VWD based on clinical phenotypes, and for monitoring drug effects.

  5. Hemophilia and von Willebrand's disease: 2. Management. Association of Hemophilia Clinic Directors of Canada.

    PubMed Central

    1995-01-01

    OBJECTIVE: To present current strategies for the treatment of hemophilia and von Willebrand's disease. OPTIONS: Prophylactic and corrective therapy with hemostatic and adjunctive agents: DDAVP (1-desamino-8-D-arginine vasopressin [desmopressin acetate]), recombinant coagulation products (human Factor VIII and human Factor VIIa) or virally inactivated plasma-derived products (high- or ultra-high-purity human Factor VIII or human Factor VIII concentrate containing von Willebrand factor activity, porcine Factor VIII, high-purity human Factor IX, human prothrombin-complex concentrate, human activated prothrombin-complex concentrate), adjunctive antifibrinolytic agents, topical thrombin and fibrin sealant. The induction of immune tolerance in patients in whom inhibitors develop should also be considered. OUTCOMES: Morbidity and quality of life associated with bleeding and treatment. EVIDENCE: Relevant clinical studies and reports published from 1974 to 1994 were examined. A search was conducted of our reprint files, MEDLINE, citations in the articles reviewed and references provided by colleagues. In the MEDLINE search the following terms were used singly or in combination: "hemophilia," "von Willebrand's disease," "Factor VIII," "Factor IX," "von Willebrand factor," "diagnosis," "management," "home care," "comprehensive care," "inhibitor," "AIDS," "hepatitis," "life expectancy," "complications," "practice guidelines," "consensus statement" and "controlled trial." The in-depth review included only articles written in English from North America and Europe that were relevant to human disease and pertinent to a predetermined outline. The availability of treatment products in Canada was also considered. VALUES: Minimizing morbidity and maximizing functional status and quality of life were given a high value. BENEFITS, HARMS AND COSTS: Proper prophylactic or early treatment with appropriate hemostatic agents minimizes morbidity and functional disability and improves quality

  6. Polymorphisms in von Willebrand factor gene promoter influence the glucocorticoid-induced increase in von Willebrand factor: the lesson learned from Cushing syndrome.

    PubMed

    Casonato, Alessandra; Daidone, Viviana; Sartorello, Francesca; Albiger, Nora; Romualdi, Chiara; Mantero, Franco; Pagnan, Antonio; Scaroni, Carla

    2008-01-01

    Cushing syndrome (CS) features high-glucocorticoid secretion and an associated hypercoagulable state often involving an increase in von Willebrand factor (VWF). To identify any influence of VWF promoter on glucocorticoid haemostatic effects, four polymorphic positions (-3267, -2708, -2659 and -2525) segregating as haplotypes 1 (GCAG) or 2 (CTGA) were analysed in 50 CS patients with high VWF (group I) and normal VWF (group II) levels, divided by ABO group. Genotype distribution differed significantly between the two groups: in group I, 25.8% had genotype 1/1, 22.6% had 2/2 and 38.7% had 1/2; in group II, 0% had genotype 1/1, 57.9% had 2/2 and 31.6% had 1/2 (P = 0.03). Patients' genotypes also differed from those of controls (P = 0.003 for group I, P = 0.03 for group II). Haplotype 1 was prevalent in group I, haplotype 2 in group II (P = 0.002), both with frequencies differing from controls (P < 0.001 and P = 0.009). By odds ratio analysis, genotype 1/1 carried a 12 times greater risk of high-VWF levels than genotype 2/2, and haplotype 1 carried a five times greater risk than haplotype 2. Our findings suggest that VWF promoter haplotypes influence the corticosteroid-mediated increase in VWF.

  7. Microsatellite (GT)(n) repeats and SNPs in the von Willebrand factor gene promoter do not influence circulating von Willebrand factor levels under normal conditions.

    PubMed

    Daidone, Viviana; Cattini, Maria Grazia; Pontara, Elena; Sartorello, Francesca; Gallinaro, Lisa; Marotti, Alberto; Scaroni, Carla; Pagnan, Antonio; Casonato, Alessandra

    2009-02-01

    Von Willebrand factor (VWF) levels vary considerably in normal individuals, influenced by inherited and acquired modulators. ABO blood group is the major inherited determinant of VWF levels, but a role has also been attributed to the VWF gene promoter, haplotype 1 (-3268G/-2709C/-2661A/-2527G) being associated with higher VWF levels than haplotype 2 (-3268C/-2709T/-2661G/-2527A), and the polymorphic locus (GT)(n) modulating the shear stress-induced activation of the VWF promoter. We characterized the (GT)(n) of the VWF promoter in 394 healthy individuals and assessed whether its variable length influenced VWF levels in normal conditions. (GT)(n) proved highly polymorphic, with alleles from 15 to 24 repeats long. (GT)(21) and (GT)(19) were the most common variants (37.4% and 34.4%, respectively). Short GT repeats (15-19) segregated mainly with haplotype 1, long GT repeats (20-24) with haplotype 2 (p < 0.0001). The number of GT repeats did not correlate with VWF levels, nor did such levels correlate with haplotypes 1 and 2, considered alone or in association with the (GT)(n) locus. We conclude that (GT)(n) and -3268/-2709/-2661/-2527 loci are in strong linkage disequilibrium. This polymorphic region of the VWF promoter does not affect VWF levels under normal conditions, though it might represent an environmentally activable VWF regulation site.

  8. Autophagy regulates endothelial cell processing, maturation and secretion of von Willebrand factor

    PubMed Central

    Torisu, Takehiro; Torisu, Kumiko; Lee, In Hye; Liu, Jie; Malide, Daniela; Combs, Christian A.; Wu, Xufeng S.; Rovira, Ilsa I.; Fergusson, Maria M.; Weigert, Roberto; Connelly, Patricia S.; Daniels, Mathew P; Komatsu, Masaaki; Cao, Liu; Finkel, Toren

    2013-01-01

    Endothelial secretion of von Willebrand factor (VWF) from intracellular organelles known as Weibel-Palade bodies (WPBs) is required for platelet adhesion to the injured vessel wall. Here, we demonstrate that WPBs are in some cases found near or within autophagosomes and that endothelial autophagosomes contain abundant VWF protein. Pharmacological inhibitors of autophagy, or knockdown of the essential autophagy genes Atg5 or Atg7, inhibits the in vitro secretion of VWF. Furthermore, while mice with an endothelial specific deletion of Atg7 have normal vessel architecture and capillary density, these animals exhibit impaired epinephrine-stimulated VWF release, reduced levels of high molecular weight VWF multimers and a corresponding elevation of their bleeding times. Endothelial deletion of Atg5 or pharmacological inhibition of autophagic flux results in a similar in vivo alteration of hemostasis. Thus, autophagy regulates endothelial VWF secretion and transient pharmacological inhibition of autophagic flux may be a useful strategy to prevent thrombotic events. PMID:24056772

  9. Antidote-controlled antithrombotic therapy targeting factor IXa and von Willebrand factor.

    PubMed

    Becker, Richard C; Oney, Sabah; Becker, Kristian C D; Sullenger, Bruce

    2009-09-01

    Thrombotic disorders and their common clinical phenotypes of acute myocardial infarction, ischemic stroke, and venous thromboembolism are the proximate cause of substantial morbidity, mortality, and health care expenditures worldwide. Accordingly, therapies designed to attenuate thrombus initiation and propagation, reflecting integrated platelet-mediated and coagulation protease-mediated events, respectively, represent a standard of care. Unfortunately, there are numerous inherent limitations of existing therapies that include target nonselectivity, variable onset and offset of pharmacodynamic effects, a narrow efficacy-safety profile, and the absence of a safe and reliable platform for either accurate titration, based on existing patient-specific, disease-specific, and clinical conditions, or active reversibility. Herein, we summarize our experience with oligonucleotide antithrombotic agents and their complementary antidotes, targeting the platelet adhesive protein von Willebrand factor and the pivotal coagulation protease factor IXa.

  10. von Willebrand factor antigen: a radial immunodiffusion method evaluated and compared with an ELISA method.

    PubMed

    Blann, A D

    1992-06-01

    A new commercial kit method for the quantification of von Willebrand factor antigen (vWFAg) by radial immunodiffusion was compared to an established ELISA technique. Major discrepancies were found between the two methods. The radial immunodiffusion method had poorer intra- and inter-assay coefficients of variation than the ELISA method, although there was adequate inter-method agreement when 100 plasma samples from controls and patients were compared. However, there was a great difference in values obtained for vWFAg in the reference sample supplied with the commercial kit and that obtained directly from the National Institute for Biological Standards and Controls. There were also differences in levels of significance when vWFAg was measured by the two techniques in different clinical groups, and standard deviations were larger when the kit method was used. It is suggested that on scientific and economic grounds, the commercial radial immunodiffusion kit does not offer a competitive advantage over the ELISA method.

  11. Von Willebrand factor and ADAMTS13 in arterial thrombosis: a systematic review and meta-analysis.

    PubMed

    Sonneveld, Michelle A H; de Maat, Moniek P M; Leebeek, Frank W G

    2014-07-01

    Von Willebrand Factor (VWF) plays an important role in hemostasis by mediating platelet adhesion and aggregation. Ultralarge VWF multimers are cleaved by ADAMTS13 in smaller, less procoagulant forms. An association between high VWF levels and cardiovascular disease has frequently been reported, and more recently also an association has been observed between low ADAMTS13 levels and arterial thrombosis. We reviewed the current literature and performed meta-analyses on the relationship between both VWF and ADAMTS13 with arterial thrombosis. Most studies showed an association between high VWF levels and arterial thrombosis. It remains unclear whether ADAMTS13 is a causal independent risk factor because the association between low ADAMTS13 and arterial thrombosis is so far only shown in case-control studies. Prospective studies are awaited. A causal role for ADAMTS13 is supported by mice studies of cerebral infarction where the infusion of recombinant human ADAMTS13 reduced the infarct size.

  12. Ibrutinib treatment affects collagen and von Willebrand factor-dependent platelet functions.

    PubMed

    Levade, Marie; David, Elodie; Garcia, Cédric; Laurent, Pierre-Alexandre; Cadot, Sarah; Michallet, Anne-Sophie; Bordet, Jean-Claude; Tam, Constantine; Sié, Pierre; Ysebaert, Loïc; Payrastre, Bernard

    2014-12-18

    The oral Bruton's tyrosine kinase inhibitor, ibrutinib, has recently demonstrated high efficiency in patients with relapsed B-cell malignancies. Occurrence of bleeding events has been reported in a subgroup of ibrutinib-treated patients. We demonstrate that ibrutinib selectively inhibits platelet signaling and functions downstream of the collagen receptor glycoprotein VI and strongly affects firm platelet adhesion on von Willebrand factor (VWF) under arterial flow. A longitudinal study of 14 patients indicated a correlation between occurrence of bleeding events and decreased platelet aggregation in response to collagen in platelet-rich plasma and firm adhesion on VWF under arterial flow. The addition of 50% untreated platelets was sufficient to efficiently reverse the effects of ibrutinib, and platelet functions recovered after treatment interruption as physiological platelet renewal occurred. These data have important clinical implications and provide a basis for hemostasis management during ibrutinib treatment.

  13. Postpartum Hemorrhage in Women with Von Willebrand Disease – A Retrospective Observational Study

    PubMed Central

    Löfgren, Signe; Chaireti, Roza; Holmström, Margareta; Bremme, Katarina; Mints, Miriam

    2016-01-01

    Introduction von Willebrand disease (VWD) is a hereditary bleeding disorder, caused by a deficiency in the levels and/or function of von Willebrand factor (VWF). Women with VWD appear to be at increased risk of experiencing postpartum hemorrhage (PPH), though the levels of VWF increase during pregnancy. There is limited knowledge of how PPH is associated with the subtype of VWD, plasma levels of other coagulations factors than VWF and given hemostatic treatment. Aims The aims were to investigate the incidence of PPH in women with VWD and to analyse the correlation between PPH and: (1) type of VWD, (2) laboratory monitoring of VWF and FVIII and (3) hemostatic drug treatment. Methods This was a retrospective observational study. The study participants (n = 34) were recruited from the Coagulation Unit, Karolinska University hospital. Fifty-nine deliveries, which occurred in 14 different obstetrics units (years 1995–2012) were included in the study. Results The incidence of primary PPH was 44%, severe primary PPH 20% and secondary PPH 12%. VWD type 3 was associated with a higher risk of experiencing severe primary PPH compared to other subtypes. FVIII:C in pregnancy was inversely correlated to blood loss during delivery. There was a significantly higher incidence of secondary PPH when the VWD diagnosis was unknown at time of delivery. Conclusions The women with VWD are at higher risk of PPH, especially those with type 3 VWD or when diagnosis is unknown prior to delivery. Identification of pregnant women with undiagnosed VWD may be of importance in order to prevent PPH. PMID:27780267

  14. In Vivo Gene Transfer Strategies to Achieve Partial Correction of von Willebrand Disease

    PubMed Central

    Wang, Lan; Rosenberg, Jonathan B.; De, Bishnu P.; Ferris, Barbara; Wang, Rui; Rivella, Stefano; Kaminsky, Stephen M.

    2012-01-01

    Abstract von Willebrand disease (VWD), the most common hereditary coagulation disorder, results from mutations in the 52-exon gene for von Willebrand factor (VWF), which encodes an 8.4-kB cDNA. Studies with VWF cDNA plasmids have demonstrated that in vivo gene transfer to the liver will correct the coagulation dysfunction in VWF−/− mice, but the correction is transient. To develop gene therapy for VWF that would mediate long-term expression of the VWF cDNA in liver, we first evaluated segmental pre-mRNA trans-splicing (SPTS) with two adeno-associated virus (AAV) serotype 8 vectors, each delivering one-half of the VWF cDNA. However, although the two vectors functioned well to generate VWF multimers after infection of cells in vitro, the efficiency of SPTS was insufficient to correct the VWF−/− mouse in vivo. As an alternative, we assessed the ability of a lentiviral vector to transfer the intact murine VWF cDNA in vivo directly to the neonatal liver of VWF−/− mice, using generation of VWF multimers, bleeding time, and bleeding volume as efficacy parameters. The VWF lentivirus generated VWF multimers and partially or completely corrected the coagulation defect on a persistent basis in 33% of the treated VWF-deficient mice. On the basis of the concept that partial persistent correction with gene transfer could be beneficial in VWD patients, these observations suggest that lentiviral delivery of VWF cDNA should be explored as a candidate for gene therapy in patients with a severe form of VWD. PMID:22482515

  15. LIM kinase/cofilin dysregulation promotes macrothrombocytopenia in severe von Willebrand disease-type 2B

    PubMed Central

    Poirault-Chassac, Sonia; Adam, Frédéric; Muczynski, Vincent; Aymé, Gabriel; Casari, Caterina; Bordet, Jean-Claude; Soukaseum, Christelle; Rothschild, Chantal; Proulle, Valérie; Pietrzyk-Nivau, Audrey; Berrou, Eliane; Christophe, Olivier D.; Rosa, Jean-Philippe; Lenting, Peter J.; Bryckaert, Marijke; Baruch, Dominique

    2016-01-01

    von Willebrand disease type 2B (VWD-type 2B) is characterized by gain-of-function mutations of von Willebrand factor (vWF) that enhance its binding to platelet glycoprotein Ibα and alter the protein’s multimeric structure. Patients with VWD-type 2B display variable extents of bleeding associated with macrothrombocytopenia and sometimes with thrombopathy. Here, we addressed the molecular mechanism underlying the severe macrothrombocytopenia both in a knockin murine model for VWD-type 2B by introducing the p.V1316M mutation in the murine Vwf gene and in a patient bearing this mutation. We provide evidence of a profound defect in megakaryocyte (MK) function since: (a) the extent of proplatelet formation was drastically decreased in 2B MKs, with thick proplatelet extensions and large swellings; and (b) 2B MKs presented actin disorganization that was controlled by upregulation of the RhoA/LIM kinase (LIMK)/cofilin pathway. In vitro and in vivo inhibition of the LIMK/cofilin signaling pathway rescued actin turnover and restored normal proplatelet formation, platelet count, and platelet size. These data indicate, to our knowledge for the first time, that the severe macrothrombocytopenia in VWD-type 2B p.V1316M is due to an MK dysfunction that originates from a constitutive activation of the RhoA/LIMK/cofilin pathway and actin disorganization. This suggests a potentially new function of vWF during platelet formation that involves regulation of actin dynamics. PMID:27734030

  16. Genetic Heterogeneity in a Large Cohort of Indian Type 3 von Willebrand Disease Patients

    PubMed Central

    Kasatkar, Priyanka; Shetty, Shrimati; Ghosh, Kanjaksha

    2014-01-01

    Background Though von Willebrand disease (VWD) is a common coagulation disorder, due to the complexity of the molecular analysis of von Willebrand factor gene (VWF), not many reports are available from this country. Large size of the gene, heterogeneous nature of mutations and presence of a highly homologous pseudogene region are the major impediments in the genetic diagnosis of VWD. The study is aimed at unravelling the molecular pathology in a large series of VWD patients from India using an effective strategy. Method We evaluated 85 unrelated Indian type 3 VWD families to identify the molecular defects using a combination of techniques i.e. PCR-RFLP, direct DNA sequencing and multiple ligation probe amplification (MLPA). Results Mutations could be characterized in 77 unrelated index cases (ICs). 59 different mutations i.e. nonsense 20 (33.9%), missense 13 (22%), splice site 4 (6.8%), gene conversions 6 (10.2%), insertions 2 (3.4%), duplication 1 (1.7%), small deletions 10 (17%) and large deletions 3 (5.1%) were identified, of which 34 were novel. Two common mutations i.e. p.R1779* and p.L970del were identified in our population with founder effect. Development of alloantibodies to VWF was seen in two patients, one with nonsense mutation (p.R2434*) and the other had a large deletion spanning exons 16–52. Conclusion The molecular pathology of a large cohort of Indian VWD patients could be identified using a combination of techniques. A wide heterogeneity was observed in the nature of mutations in Indian VWD patients. PMID:24675615

  17. Higher and lower active circulating VWF levels: different facets of von Willebrand disease.

    PubMed

    Casonato, Alessandra; Pontara, Elena; Morpurgo, Margherita; Sartorello, Francesca; De Groot, Philip G; Cattini, Maria G; Daidone, Viviana; De Marco, Luigi

    2015-12-01

    Most circulating von Willebrand factor (VWF) is normally inactive and incapable of binding platelets, but numerous disorders may modify the proportion of active VWF. We explored active VWF levels in patients with von Willebrand disease (VWD) whose VWF had a higher affinity for platelet glycoprotein (GP)Ib, but different susceptibilities to ADAMTS13 and multimer patterns (9 patients lacking large multimers, 10 with a normal pattern); 12 patients with VWF C2362F and R1819_C1948delinsS mutations, which make VWF resistant to ADAMTS13 were also studied. Type 2B patients with abnormal or normal multimers had significantly more active VWF (3·33 ± 1·6 and 3·74 ± 0·74, respectively; normal 0·99 ± 0·23). The type of VWF mutation influenced VWF activation: V1316M was associated with the highest levels in patients with abnormal multimers, and R1341W in those with normal multimers. Pregnancy induced gradually rising active VWF levels and declining platelet counts in one type 2B VWD patient without large multimers. Active VWF levels dropped significantly in patients homozygous for the C2362F mutation or heterozygous for R1819_C1948delinsS mutations (0·2 ± 0·03 and 0·23 ± 0·1, respectively), and less in cases heterozygous for the VWF C2362F mutation (0·55 ± 0·17). We demonstrate that VWF may be more or less activated, with or without any direct involvement of the A1 domain, and regardless of ADAMTS13.

  18. Technological advances in diagnostic testing for von Willebrand disease: new approaches and challenges.

    PubMed

    Hayward, C P M; Moffat, K A; Graf, L

    2014-06-01

    Diagnostic tests for von Willebrand disease (VWD) are important for the assessment of VWD, which is a commonly encountered bleeding disorder worldwide. Technical innovations have been applied to improve the precision and lower limit of detection of von Willebrand factor (VWF) assays, including the ristocetin cofactor activity assay (VWF:RCo) that uses the antibiotic ristocetin to induce plasma VWF binding to glycoprotein (GP) IbIXV on target platelets. VWF-collagen-binding assays, depending on the type of collagen used, can improve the detection of forms of VWD with high molecular weight VWF multimer loss, although the best method is debatable. A number of innovations have been applied to VWF:RCo (which is commonly performed on an aggregometer), including replacing the target platelets with immobilized GPIbα, and quantification by an enzyme-linked immunosorbent assay (ELISA), immunoturbidimetric, or chemiluminescent end-point. Some common polymorphisms in the VWF gene that do not cause bleeding are associated with falsely low VWF activity by ristocetin-dependent methods. To overcome the need for ristocetin, some new VWF activity assays use gain-of-function GPIbα mutants that bind VWF without the need for ristocetin, with an improved precision and lower limit of detection than measuring VWF:RCo by aggregometry. ELISA of VWF binding to mutated GPIbα shows promise as a method to identify gain-of-function defects from type 2B VWD. The performance characteristics of many new VWF activity assays suggest that the detection of VWD, and monitoring of VWD therapy, by clinical laboratories could be improved through adopting newer generation VWF assays.

  19. The role of von Willebrand factor and fibrinogen in platelet aggregation under varying shear stress.

    PubMed Central

    Ikeda, Y; Handa, M; Kawano, K; Kamata, T; Murata, M; Araki, Y; Anbo, H; Kawai, Y; Watanabe, K; Itagaki, I

    1991-01-01

    Exposure of platelets to shear stress leads to aggregation in the absence of exogenous agonists. We have now found that different adhesive proteins and platelet membrane glycoproteins are involved in aggregation depending on the shear stress conditions and the concentration of divalent cations in the medium. When blood is collected with trisodium citrate as anticoagulant, which causes a decrease in the levels of external ionized calcium ([Ca2+]o), platelet aggregation can be induced under low shear force (12 dyn/cm2) and is mediated by fibrinogen binding to the glycoprotein IIb-IIIa complex. Aggregates formed under these conditions are not stable, and when shear force is increased to 68 dyn/cm2, disaggregation results. By contrast, platelets from blood collected with hirudin as anticoagulant, wherein [Ca2+]o is within normal plasma levels, do not undergo low shear-induced aggregation; however, after exposure to a shear force above 80 dyn/cm2, aggregation is observed but only when von Willebrand factor is present and can interact with both its platelet binding sites, glycoprotein Ib-IX and glycoprotein IIb-IIIa. Fibrinogen is not involved in high shear-induced aggregation which, in fact, occurs normally in patients with severe afibrinogenemia. Thus, von Willebrand factor in the absence of exogenous agonists can mediate platelet aggregation in experimental conditions that may mimic the hemorheological situation of partially occluded arteries. This pathway of platelet aggregation involving only one adhesive ligand and two membrane adhesion receptors may play a relevant role in thrombogenesis. PMID:2010539

  20. In vitro and in vivo characterization of a high-purity, solvent/detergent-treated factor VIII concentrate: evidence for its therapeutic efficacy in von Willebrand's disease.

    PubMed

    Mazurier, C; De Romeuf, C; Parquet-Gernez, A; Goudemand, M

    1989-07-01

    A factor VIII (FVIII) concentrate, virus-inactivated by the solvent/detergent procedure, was studied in vitro. In contrast with most high-purity, virus-inactivated FVIII concentrates, it contains not only high levels of von Willebrand factor (vWF) antigen and ristocetin cofactor activity but also high molecular weight forms of von Willebrand factor. Furthermore, it is able to promote platelet adhesion on collagen in a perfusion system. In vivo studies performed in patients with different types of von Willebrand's disease provided evidence that this concentrate corrects Duke's bleeding time and prevents or stops haemorrhages. Thus, the particular advantages of this FVIII/vWF preparation are safety, low content of contamination proteins, and efficacy in von Willebrand's disease.

  1. Co-inheritance of mild hemophilia A and heterozygosity for type 2N von Willebrand disease: a diagnostic and therapeutic challenge.

    PubMed

    Lindsay, Holly; Bergstrom, Katie; Srivaths, Lakshmi

    2014-10-01

    Hemophilia A and von Willebrand disease are the two most common inherited bleeding disorders. Despite their frequency, however, there are very few reports of co-inheritance of the two disorders. We present the first report of a patient with mild hemophilia A and heterozygosity for type 2N von Willebrand disease (VWD). We discuss the patient's phenotype and highlight the diagnostic and therapeutic challenges caused by this co-inheritance.

  2. The influence of smoking on von Willebrand factor is already manifest in healthy adolescent females: the Floren-teen (Florence Teenager) Study.

    PubMed

    Prisco, D; Fedi, S; Brunelli, T; Chiarugi, L; Lombardi, A; Gianni, R; Santoro, E; Cappelletti, C; Pepe, G; Gensini, G F; Abbate, R

    1999-01-01

    The early onset of atherosclerosis and the involvement of physiological biochemical, and environmental factors in its pathogenesis is well documented. Few data are available on the role of risk factors related to hemostasis in the pathogenesis of atherosclerosis in the young and, in particular, little information is available on adolescent populations. In the Study of Preventive Medicine and Education Program (Floren-teen Study), von Willebrand factor, a risk factor for cardiovascular disorder, was studied, together with classical cardiovascular risk factors, in apparently healthy students from two high schools in Florence. Familial and personal history, physical examination, and cardiovascular risk factors were evaluated in 144 students (aged 17-19 years). Blood was withdrawn to assess von Willebrand factor (ELISA) and lipid parameters. Levels of von Willebrand factor were significantly higher (P<0.044) in smokers than in nonsmokers and were correlated with the number of cigarettes per day in the whole group (P=0.01) and in females (P=0.006). In females a positive correlation was observed between von Willebrand factor and high-density lipoprotein cholesterol (P=0.0365). There was no significant correlation between von Willebrand factor and blood pressure or between von Willebrand factor and physical activity. In conclusion, this study shows an association between levels of von Willebrand factor and smoking habits and is the first show that even a brief period of smoking affects levels of von Willebrand factor in healthy adolescent females independently of other risk factors. These results stress the relevance of extending prevention programs to reduce smoking in high school students.

  3. Binding of factor VIII to von willebrand factor is enabled by cleavage of the von Willebrand factor propeptide and enhanced by formation of disulfide-linked multimers.

    PubMed

    Bendetowicz, A V; Morris, J A; Wise, R J; Gilbert, G E; Kaufman, R J

    1998-07-15

    von Willebrand factor (vWF) is a multimeric adhesive glycoprotein with one factor VIII binding site/subunit. Prior reports suggest that posttranslational modifications of vWF, including formation of N-terminal intersubunit disulfide bonds and subsequent cleavage of the propeptide, influence availability and/or affinity of factor VIII binding sites. We found that deletion of the vWF propeptide produced a dimeric vWF molecule lacking N-terminal intersubunit disulfide bonds. This molecule bound fluorescein-labeled factor VIII with sixfold lower affinity than multimeric vWF in an equilibrium flow cytometry assay (approximate KDs, 5 nmol/L v 0.9 nmol/L). Coexpression of propeptide-deleted vWF with the vWF propeptide in trans yielded multimeric vWF that displayed increased affinity for factor VIII. Insertion of an alanine residue at the N-terminus of the mature vWF subunit destroyed binding to factor VIII, indicating that the native mature N-terminus is required for factor VIII binding. The requirement for vWF propeptide cleavage was shown by (1) a point mutation of the vWF propeptide cleavage site yielding pro-vWF that was defective in factor VIII binding and (2) correlation between efficiency of intracellular propeptide cleavage and factor VIII binding. Furthermore, in a cell-free system, addition of the propeptide-cleaving enzyme PACE/furin enabled factor VIII binding in parallel with propeptide cleavage. Our results indicate that high-affinity factor VIII binding sites are located on N-terminal disulfide-linked vWF subunits from which the propeptide has been cleaved.

  4. Data on the purification and crystallization of the loss-of-function von Willebrand disease variant (p.Gly1324Ser) of the von Willebrand factor A1 domain.

    PubMed

    Campbell, James C; Tischer, Alexander; Machha, Venkata; Moon-Tasson, Laurie; Sankaran, Banumathi; Kim, Choel; Auton, Matthew

    2016-06-01

    von Willebrand factor׳s (VWF) primary hemostatic responsibility is to deposit platelets at sites of vascular injury to prevent bleeding. This function is mediated by the interaction between the VWF A1 domain and the constitutively active platelet receptor, GPIbα. The crystal structure of the A1 domain harboring the von Willebrand disease (vWD) type 2M mutation p.Gly1324Ser has been recently published in the Journal of Biological Chemistry describing its effect on the function and structural stability of the A1 domain of VWF, "Mutational constraints on local unfolding inhibit the rheological adaptation of von Willebrand factor" [1]. The mutation introduces a side chain that thermodynamically stabilizes the domain by reducing the overall flexibility of the A1-GPIbα binding interface resulting in loss-of-function and bleeding due to the inability of A1 to adapt to a binding competent conformation under the rheological shear stress blood flow. In this data article we describe the production, quality control and crystallization of the p.Gly1324Ser vWD variant of the A1 domain of VWF. p.Gly1324Ser A1 was expressed in Escherichia coli as insoluble inclusion bodies. After the preparation of the inclusion bodies, the protein was solubilized, refolded, purified by affinity chromatography and crystallized. The crystal structure of the p.Gly1324Ser mutant of the A1 domain is deposited at the Protein Data Bank PDB: 5BV8.

  5. Type 2B von Willebrand disease associated with the release of platelet agglutinates from megakaryocytes in the bone marrow.

    PubMed

    Slayton, William B; Patel, Milin; Sola-Visner, Martha; Harris, Neil; Rivers, Angela; Montgomery, Robert R; Friedman, Kenneth D

    2008-09-01

    We report a child with thrombocytopenia since birth, circulating platelet agglutinates, and a tendency to bleed. A bone marrow aspirate revealed large platelet clumps within the bone marrow and megakaryocyte nuclei surrounded by halos of clumped platelets. Laboratory evaluation revealed type 2B von Willebrand disease. Gene sequencing revealed a G to C mutation at base 3923 of the VWF gene. This mutation was previously described in a family with circulating platelet clumps and abnormal megakaryopoiesis with release of clumped platelets in culture. This same mutation was previously described in a family with circulating platelet aggregates and abnormalities of platelet release from megakaryocytes in vitro. Presence of megakaryocytes with halos of clumped platelets in our patient suggests that platelet agglutinate occurs in the bone marrow in some type 2B von Willebrand disease patients.

  6. IgG kappa monoclonal gammopathy of undetermined significance presenting as acquired type III Von Willebrand syndrome.

    PubMed

    Howard, Christin R; Lin, Tara L; Cunningham, Mark T; Lipe, Brea C

    2014-09-01

    Acquired von Willebrand syndrome (AVWS) is a rare bleeding disorder associated with hematoproliferative disorders, autoimmune conditions, neoplasia and cardiovascular disorders that often present a diagnostic challenge. Monoclonal gammopathy of undetermined significance (MGUS) is one of the most common causes of AVWS that typically presents later in life with mucocutaneous or postsurgical bleeding and multimers consistent with type I or II von Willebrand disease (VWD). Here, we present the case of a patient with a 32-year history of type III VWD that was ultimately found to be AVWS related to an IgG MGUS. In this case report, we highlight the diagnostic challenges of AVWS to ensure proper identification and potentially lifesaving treatment of this rare disorder.

  7. P-selectin can promote thrombus propagation independently of both von Willebrand factor and thrombospondin-1 in mice.

    PubMed

    Prakash, P; Nayak, M K; Chauhan, A K

    2017-02-01

    Essentials The main receptor for platelet glycoprotein (GP) Ibα is von Willebrand factor (VWF). P-selectin and thrombospondin-1 (TSP1) have been suggested as counter receptors for GPIbα. In a laser injury model, P-selectin promotes thrombus propagation independently of VWF and TSP1. In a laser injury model, thrombus persists in interleukin-4 receptor α/GPIbα-transgenic mice.

  8. Human von Willebrand factor gene sequences target expression to a subpopulation of endothelial cells in transgenic mice.

    PubMed

    Aird, W C; Jahroudi, N; Weiler-Guettler, H; Rayburn, H B; Rosenberg, R D

    1995-05-09

    The present study was undertaken to define the 5' and 3' regulatory sequences of human von Willebrand factor gene that confer tissue-specific expression in vivo. Transgenic mice were generated bearing a chimeric construct that included 487 bp of 5' flanking sequence and the first exon fused in-frame to the Escherichia coli lacZ gene. In situ histochemical analyses in independent lines demonstrated that the von Willebrand factor promoter targeted expression of LacZ to a subpopulation of endothelial cells in the yolk sac and adult brain. LacZ activity was absent in the vascular beds of the spleen, lung, liver, kidney, testes, heart, and aorta, as well as in megakaryocytes. In contrast, in mice containing the lacZ gene targeted to the thrombomodulin locus, the 5-bromo-4-chloro-3-indolyl beta-D-galactopyranoside reaction product was detected throughout the vascular tree. These data highlight the existence of regional differences in endothelial cell gene regulation and suggest that the 733-bp von Willebrand factor promoter may be useful as a molecular marker to investigate endothelial cell diversity.

  9. Diagnostic challenges in patients with bleeding phenotype and von Willebrand exon 28 polymorphism p.D1472H.

    PubMed

    Francis, J C; Hui, S K; Mahoney, D; Dietrich, J E; Friedman, K D; Soundar, E; Srivaths, L V

    2014-05-01

    Exon 28 polymorphism p.D1472H is associated with significantly lower von Willebrand Ristocetin cofactor activity (VWF:RCoF) to von Willebrand antigen (VWF:Ag) ratio compared to normal, but has been reported as not conferring haemorrhagic risk. The impact of this polymorphism while assessing symptomatic patients for von Willebrand disease (VWD) has not been previously analysed. We retrospectively reviewed charts of children with clinically significant bleeding and abnormal VW panel who underwent VW exon 28 analysis. Twenty-three of 63 patients studied had p.D1472H. Of these 23 patients, 6 with borderline low VWF:RCo were given provisional diagnosis of VWD type 1 by treating physicians, which could be alternatively explained as due to the effect of p.D1472H. None of the patients with low VWF:RCo, decreased VWF:RCo/VWF:Ag ratio and p.D1472H had VWD type 2M mutations identified. This study illustrates the challenge in diagnosing VWD using ristocetin-based VW assay in symptomatic patients with p.D1472H.

  10. A Laboratory Phenotype/Genotype Correlation of 1167 French Patients From 670 Families With von Willebrand Disease

    PubMed Central

    Veyradier, Agnès; Boisseau, Pierre; Fressinaud, Edith; Caron, Claudine; Ternisien, Catherine; Giraud, Mathilde; Zawadzki, Christophe; Trossaert, Marc; Itzhar-Baïkian, Nathalie; Dreyfus, Marie; d’Oiron, Roseline; Borel-Derlon, Annie; Susen, Sophie; Bezieau, Stéphane; Denis, Cécile V.; Goudemand, Jenny

    2016-01-01

    Abstract von Willebrand disease (VWD) is a genetic bleeding disease due to a defect of von Willebrand factor (VWF), a glycoprotein crucial for platelet adhesion to the subendothelium after vascular injury. VWD include quantitative defects of VWF, either partial (type 1 with VWF levels <50 IU/dL) or virtually total (type 3 with undetectable VWF levels) and also qualitative defects of VWF (type 2 variants with discrepant antigenic and functional VWF levels). The most bleeding forms of VWD usually do not concern type 1 patients with the mildest VWF defects (VWF levels between 30 and 50 IU/dL). The French reference center for VWD performed a laboratory phenotypic and genotypic analysis in 1167 VWD patients (670 families) selected by their basic biologic phenotype: type 3, type 2, and type 1 with VWF levels <30 IU/dL. In these patients indeed, to achieve an accurate diagnosis of VWD type and subtype is crucial for the management (treatment and genetic counseling). A phenotype/genotype correlation was present in 99.3% of cases; 323 distinct VWF sequence variations (58% of novel) were identified (missense 67% versus truncating 33%). The distribution of VWD types was: 25% of type 1, 8% of type 3, 66% of type 2 (2A: 18%, 2B: 17%, 2M: 19%, 2N: 12%), and 1% of undetermined type. Type 1 VWD was related either to a defective synthesis/secretion or to an accelerated clearance of VWF. In type 3 VWD, bi-allelic mutations of VWF were found in almost all patients. In type 2A, the most frequent mechanism was a hyper-proteolysis of VWF. Type 2B showed 85% of patients with deleterious mutations (distinct from type 2B New York). Type 2M was linked to a defective binding of VWF to platelet glycoprotein Ib or to collagen. Type 2N VWD included almost half type 2N/3. This biologic study emphasizes the complex mechanisms for both quantitative and qualitative VWF defects in VWD. In addition, this study provides a new epidemiologic picture of the most bleeding forms of VWD in which

  11. Functional assessment of von Willebrand factor expression by cancer cells of non-endothelial origin.

    PubMed

    Mojiri, Anahita; Stoletov, Konstantin; Lorenzana Carrillo, Maria Areli; Willetts, Lian; Jain, Saket; Godbout, Roseline; Jurasz, Paul; Sergi, Consolato M; Eisenstat, David D; Lewis, John D; Jahroudi, Nadia

    2016-12-27

    Von Willebrand factor (VWF) is a highly adhesive procoagulant molecule that mediates platelet adhesion to endothelial and subendothelial surfaces. Normally it is expressed exclusively in endothelial cells (ECs) and megakaryocytes. However, a few studies have reported VWF detection in cancer cells of non-endothelial origin, including osteosarcoma. A role for VWF in cancer metastasis has long been postulated but evidence supporting both pro- and anti-metastatic roles for VWF has been presented. We hypothesized that the role of VWF in cancer metastasis is influenced by its cellular origin and that cancer cell acquisition of VWF expression may contribute to enhanced metastatic potential. We demonstrated de novo expression of VWF in glioma as well as osteosarcoma cells. Endothelial monolayer adhesion, transmigration and extravasation capacities of VWF expressing cancer cells were shown to be enhanced compared to non-VWF expressing cells, and were significantly reduced as a result of VWF knock down. VWF expressing cancer cells were also detected in patient tumor samples of varying histologies. Analyses of the mechanism of transcriptional activation of the VWF in cancer cells demonstrated a pattern of trans-activating factor binding and epigenetic modifications consistent overall with that observed in ECs. These results demonstrate that cancer cells of non-endothelial origin can acquire de novo expression of VWF, which can enhance processes, including endothelial and platelet adhesion and extravasation, that contribute to cancer metastasis.

  12. Ultrastructural demonstration of tubular inclusions coinciding with von Willebrand factor in pig megakaryocytes.

    PubMed

    Cramer, E M; Breton-Gorius, J; Beesley, J E; Martin, J F

    1988-06-01

    The appearance of von Willebrand factor (vWF) in bone marrow megakaryocytes was studied by standard electron microscopy (EM) and immuno-EM using an original purification technique. Eighty percent pure megakaryocytes were isolated from porcine rib bone marrow using Percoll gradients followed by counterflow centrifugation. Activation was prevented by prostacyclin and prefixation with low concentrations of glutaraldehyde. In early megakaryoblasts, standard EM revealed the presence of tubular structures in the small vesicles located in the Golgi area, in the small immature alpha-granules and in the rare mature alpha-granules. Immunolabeling for vWF was simultaneously observed in small vesicles and small alpha-granules, mainly in the Golgi zone. In mature megakaryocytes, standard EM showed that tubular structures were numerous, regularly spaced, and aligned in parallel. Immunolabeling for vWF was intense, restricted to the alpha-granules, and distributed in a similar manner to porcine platelets. Gold particles were located eccentrically at one pole of the alpha-granule, labeling only its periphery or outlining one side of an elongated granule. Tubule profiles could be seen underlying the immunolabeling and were usually located at one side of the granule. In conclusion, this study demonstrates the presence of tubular structures in megakaryocyte alpha-granules, their association with vWF, and the appearance of both in the Golgi-associated vesicles.

  13. Mechanisms underlying acquired von Willebrand syndrome associated with an IgM paraprotein.

    PubMed

    Mayerhofer, M; Haushofer, A; Kyrle, P A; Chott, A; Müllner, C; Quehenberger, P; Worel, N; Traby, L; Eichinger, S

    2009-09-01

    Acquired von Willebrand (vW) syndrome is a rare bleeding disorder which is frequently associated with immunological, malignant or cardiovascular disorders. The underlying pathomechanisms, particularly in patients with IgM monoclonal gammopathies, often remain unknown. We report a patient with indolent small B-cell lymphoma (immunocytoma) and plasmacytic differentiation with an IgM kappa paraprotein who was admitted with retroperitoneal haematoma. Medical history and coagulation testing were consistent with acquired vW syndrome. vW immunohistochemistry showed normal cytoplasmic labelling of endothelial cells and megakaryocytes, whereas the lymphomatous infiltrate was negative. Acquired vW syndrome due to adsorption of vW factor on malignant cells was thus excluded. In the multimeric analysis, all multimers were present similar to that in type 1 vW syndrome, but the triplet structures were blurred. The bands on serum immunofixation electrophoresis were also atypically broadened, which suggested complex formation between the IgM and vW factor. Immunoprecipitation studies showed that the 176-kDa proteolytic fragment of vW factor co-precipitated with the IgM paraprotein in the patient but not in the controls, suggesting a specific interaction between vW factor and the paraprotein in the patient. The patient required surgery and was successfully managed by chemotherapy consisting of rituximab and fludarabin as well as plasma exchange.

  14. Flow and delta-P dictate where thrombin, fibrin, and von Willebrand Factor will be found.

    PubMed

    Diamond, Scott L

    2016-05-01

    Hemostasis occurs in two different topological scenarios: complete severing of a vessel or disruption of the vessel wall. Either to meet the daily rigors of active life or during an acute trauma, hemostasis involves the regulated and self-limiting production of thrombin to stop bleeding. In contrast, arterial and venous thrombosis typically involves the unregulated, intraluminal growth of a clot, in the absence of bleeding. For either hemostasis or thrombosis, the presence of flow and pressure gradients (delta-P, ΔP) dictates when and where thrombin and fibrin are located and in what quantity. For hemostatic clots, fibrin formation helped limit clot growth. We found that γ'-fibrinogen had a role in limiting clot growth via anti-thrombin activity at venous, but not arterial conditions. For hemophilic blood, severe factor deficiency (<1% healthy) led to a defect in both platelet and fibrin deposition under flow. However, moderate deficiency, which is associated with a less severe bleeding phenotype, had normalized platelet function but still lacked fibrin production. We conclude signaling levels of thrombin can be generated during moderate hemophilia to sufficiently activate platelets to achieve primary hemostasis, even if fibrin formation remains defective. Finally, as a clot grows, shear stresses can become sufficiently extreme in diseased arteries to drive von Willebrand Factor self-association into massive fibers, potentially the final burst of clot growth towards full thrombotic occlusion.

  15. Analysis of von Willebrand factor multimers using a commercially available enhanced chemiluminescence kit.

    PubMed Central

    Cumming, A M; Wensley, R T

    1993-01-01

    AIMS--To develop a rapid, sensitive, and safe method for the analysis of von Willebrand factor (vWf) multimers in plasma or platelet lysates. METHOD--Analysis of vWf multimers was carried out by sodium dodecyl sulphate-agarose discontinuous gel electrophoresis followed by protein transfer to nitrocellulose membranes by western blotting. Blots were probed using horseradish peroxidase (HRP) conjugated rabbit anti-vWf; visualisation of vWf multimers was achieved using a commercially available enhanced chemi-Luminescence (ECL) kit for detecting HRP labelled antibodies on western blots. RESULTS--Electrophoretic transfer of vWf multimers to nitrocellulose membranes, including the higher molecular weight forms, was achieved satisfactorily and there was good resolution of individual multimer bands and of the triplet sub-band structure. Type II vWD variants were readily identifiable. The use of ECL conferred a high degree of sensitivity to the method and the end result on autoradiography film provided a permanent record which did not fade and which was suitable for scanning densitometry. CONCLUSION--The method for vWf multimer analysis described here is sensitive, simple to carry out, uses minimal amounts of reagents, produces results within 48 hours, and does not require the use of potentially hazardous radioactive materials or carcinogenic enzyme substrates. Images PMID:8320330

  16. Molecular evolution of the nuclear von Willebrand factor gene in mammals and the phylogeny of rodents.

    PubMed

    Huchon, D; Catzeflis, F M; Douzery, E J

    1999-05-01

    Nucleotide sequences of exon 28 of the von Willebrand Factor (vWF) were analyzed for a representative sampling of rodent families and eutherian orders, with one marsupial sequence as outgroup. The aim of this study was to test if inclusion of an increased taxonomic diversity in molecular analyses would shed light on three uncertainties concerning rodent phylogeny: (1) relationships between rodent families, (2) Rodentia monophyly, and (3) the sister group relationship of rodents and lagomorphs. The results did not give evidence of any particular rodent pattern of molecular evolution relative to a general eutherian pattern. Base compositions and rates of evolution of vWF sequences of rodents were in the range of placental variation. The 10 rodent families studied here cluster in five clades: Hystricognathi, Sciuridae and Aplodontidae (Sciuroidea), Muridae, Dipodidae, and Gliridae. Among hystricognaths, the following conclusions are drawn: a single colonization event in South America by Caviomorpha, a paraphyly of Old World and New World porcupines, and an African origin for Old World porcupines. Despite a broader taxonomic sampling diversity, we did not obtain a robust answer to the question of Rodentia monophyly, but in the absence of any other alternative, we cannot reject the hypothesis of a single origin of rodents. Moreover, the phylogenetic position of Lagomorpha remains totally unsettled.

  17. Characterization of Conformation-Sensitive Antibodies to ADAMTS13, the von Willebrand Cleavage Protease

    PubMed Central

    Sauna, Zuben E.; Okunji, Chinyere; Hunt, Ryan C.; Gupta, Tanvi; Allen, Courtni E.; Plum, Elizabeth; Blaisdell, Adam; Grigoryan, Vahan; S, Geetha; Fathke, Robert; Soejima, Kenji; Kimchi-Sarfaty, Chava

    2009-01-01

    Background The zinc metalloprotease ADAMTS13 is a multidomain protein that cleaves von Willebrand Factor (VWF) and is implicated in Thrombotic Thrombocytopenic Purpura (TTP) pathogenesis. Understanding the mechanism of this protein is an important goal. Conformation sensitive antibodies have been used to monitor protein conformation and to decipher the molecular mechanism of proteins as well as to distinguish functional and non-functional mutants. Methodology/Principal Findings We have characterized several antibodies against ADAMTS13, both monoclonal and polyclonal. We have used flow cytometry to estimate the binding of these antibodies to ADAMTS13 and demonstrate that antibodies raised against the TSP and disintegrin domains detect conformation changes in the ADAMTS13. Thus for example, increased binding of these antibodies was detected in the presence of the substrate (VWF), mainly at 37°C and not at 4°C. These antibodies could also detect differences between wild-type ADAMTS13 and the catalytically deficient mutant (P475S). The flow cytometry approach also allows us to estimate the reactivity of the antibody as well as its apparent affinity. Conclusions/Significance Our results suggest that these antibodies may serve as useful reagents to distinguish functional and non-functional ADAMTS13 and analyze conformational transitions to understand the catalytic mechanism. PMID:19654870

  18. von-Willebrand factor influences blood brain barrier permeability and brain inflammation in experimental allergic encephalomyelitis.

    PubMed

    Noubade, Rajkumar; del Rio, Roxana; McElvany, Benjamin; Zachary, James F; Millward, Jason M; Wagner, Denisa D; Offner, Halina; Blankenhorn, Elizabeth P; Teuscher, Cory

    2008-09-01

    Weibel-Palade bodies within endothelial cells are secretory granules known to release von Willebrand Factor (VWF), P-selectin, chemokines, and other stored molecules following histamine exposure. Mice with a disrupted VWF gene (VWFKO) have endothelial cells that are deficient in Weibel-Palade bodies. These mice were used to evaluate the role of VWF and/or Weibel-Palade bodies in Bordetella pertussis toxin-induced hypersensitivity to histamine, a subphenotype of experimental allergic encephalomyelitis, the principal autoimmune model of multiple sclerosis. No significant differences in susceptibility to histamine between wild-type and VWFKO mice were detected after 3 days; however, histamine sensitivity persisted significantly longer in VWFKO mice. Correspondingly, encephalomyelitis onset was earlier, disease was more severe, and blood brain barrier (BBB) permeability was significantly increased in VWFKO mice, as compared with wild-type mice. Moreover, inflammation was selectively increased in the brains, but not spinal cords, of VWFKO mice as compared with wild-type mice. Early increases in BBB permeability in VWFKO mice were not due to increased encephalitogenic T-cell activity since BBB permeability did not differ in adjuvant-treated VWFKO mice as compared with littermates immunized with encephalitogenic peptide plus adjuvant. Taken together, these data indicate that VWF and/or Weibel-Palade bodies negatively regulate BBB permeability changes and autoimmune inflammatory lesion formation within the brain elicited by peripheral inflammatory stimuli.

  19. Intracellular trafficking of factor VIII to von Willebrand factor storage granules.

    PubMed Central

    Rosenberg, J B; Foster, P A; Kaufman, R J; Vokac, E A; Moussalli, M; Kroner, P A; Montgomery, R R

    1998-01-01

    In plasma, von Willebrand factor (vWf) associates with Factor VIII (FVIII); however, the site at which these proteins first interact has not been defined. Administration of 1-desamino-8-D-arginine vasopressin (DDAVP) causes a rapid, concomitant elevation in plasma levels of both vWf and FVIII, suggesting the existence of a DDAVP-releasable storage pool for both proteins. To determine whether vWf and FVIII can associate intracellularly and colocalize to storage vesicles, we transfected AtT-20 cells with vWf and FVIII expression plasmids. FVIII alone was not detectable within storage granules; however, transfection of vWf cDNA into the same cell caused FVIII to alter its intracellular trafficking and to undergo granular storage, colocalizing to the vWf-containing granules. In contrast, colocalization of FVIII was not observed when these cells were transfected with plasmids encoding defective FVIII-binding vWf mutants. Transfection of bovine endothelial cells with FVIII further demonstrated vesicular storage of FVIII with vWf in Weibel-Palade bodies. Since gene therapy of hemophilia A may ultimately target endothelium or hematopoietic stem cells, the interaction between vWf and FVIII within a secretory cell is important. Thus, vWf can alter the intracellular trafficking of FVIII from a constitutive to a regulated secretory pathway, thereby producing an intracellular storage pool of both proteins. PMID:9449695

  20. Zyxin regulates endothelial von Willebrand factor secretion by reorganizing actin filaments around exocytic granules

    PubMed Central

    Han, Xiaofan; Li, Pin; Yang, Zhenghao; Huang, Xiaoshuai; Wei, Guoqin; Sun, Yujie; Kang, Xuya; Hu, Xueting; Deng, Qiuping; Chen, Liangyi; He, Aibin; Huo, Yingqing; Li, Dong; Betzig, Eric; Luo, Jincai

    2017-01-01

    Endothelial exocytosis of Weibel–Palade body (WPB) is one of the first lines of defence against vascular injury. However, the mechanisms that control WPB exocytosis in the final stages (including the docking, priming and fusion of granules) are poorly understood. Here we show that the focal adhesion protein zyxin is crucial in this process. Zyxin downregulation inhibits the secretion of von Willebrand factor (VWF), the most abundant cargo in WPBs, from human primary endothelial cells (ECs) induced by cAMP agonists. Zyxin-deficient mice exhibit impaired epinephrine-stimulated VWF release, prolonged bleeding time and thrombosis, largely due to defective endothelial secretion of VWF. Using live-cell super-resolution microscopy, we visualize previously unappreciated reorganization of pre-existing actin filaments around WPBs before fusion, dependent on zyxin and an interaction with the actin crosslinker α-actinin. Our findings identify zyxin as a physiological regulator of endothelial exocytosis through reorganizing local actin network in the final stage of exocytosis. PMID:28256511

  1. Single-molecule force measurements of the polymerizing dimeric subunit of von Willebrand factor

    NASA Astrophysics Data System (ADS)

    Wijeratne, Sithara S.; Li, Jingqiang; Yeh, Hui-Chun; Nolasco, Leticia; Zhou, Zhou; Bergeron, Angela; Frey, Eric W.; Moake, Joel L.; Dong, Jing-fei; Kiang, Ching-Hwa

    2016-01-01

    Von Willebrand factor (VWF) multimers are large adhesive proteins that are essential to the initiation of hemostatic plugs at sites of vascular injury. The binding of VWF multimers to platelets, as well as VWF proteolysis, is regulated by shear stresses that alter VWF multimeric conformation. We used single molecule manipulation with atomic force microscopy (AFM) to investigate the effect of high fluid shear stress on soluble dimeric and multimeric forms of VWF. VWF dimers are the smallest unit that polymerizes to construct large VWF multimers. The resistance to mechanical unfolding with or without exposure to shear stress was used to evaluate VWF conformational forms. Our data indicate that, unlike recombinant VWF multimers (RVWF), recombinant dimeric VWF (RDVWF) unfolding force is not altered by high shear stress (100 dynes/cm2 for 3 min at 37°C ). We conclude that under the shear conditions used (100 dynes/cm2 for 3 min at 37°C ) , VWF dimers do not self-associate into a conformation analogous to that attained by sheared large VWF multimers.

  2. Force sensing by the vascular protein von Willebrand factor is tuned by a strong intermonomer interaction

    PubMed Central

    Müller, Jochen P.; Mielke, Salomé; Löf, Achim; Obser, Tobias; Beer, Christof; Bruetzel, Linda K.; Pippig, Diana A.; Vanderlinden, Willem; Lipfert, Jan; Schneppenheim, Reinhard; Benoit, Martin

    2016-01-01

    The large plasma glycoprotein von Willebrand factor (VWF) senses hydrodynamic forces in the bloodstream and responds to elevated forces with abrupt elongation, thereby increasing its adhesiveness to platelets and collagen. Remarkably, forces on VWF are elevated at sites of vascular injury, where VWF’s hemostatic potential is important to mediate platelet aggregation and to recruit platelets to the subendothelial layer. Adversely, elevated forces in stenosed vessels lead to an increased risk of VWF-mediated thrombosis. To dissect the remarkable force-sensing ability of VWF, we have performed atomic force microscopy (AFM)-based single-molecule force measurements on dimers, the smallest repeating subunits of VWF multimers. We have identified a strong intermonomer interaction that involves the D4 domain and critically depends on the presence of divalent ions, consistent with results from small-angle X-ray scattering (SAXS). Dissociation of this strong interaction occurred at forces above ∼50 pN and provided ∼80 nm of additional length to the elongation of dimers. Corroborated by the static conformation of VWF, visualized by AFM imaging, we estimate that in VWF multimers approximately one-half of the constituent dimers are firmly closed via the strong intermonomer interaction. As firmly closed dimers markedly shorten VWF’s effective length contributing to force sensing, they can be expected to tune VWF’s sensitivity to hydrodynamic flow in the blood and to thereby significantly affect VWF’s function in hemostasis and thrombosis. PMID:26787887

  3. Immunocytochemical distribution of WARP (von Willebrand A domain-related protein) in the inner ear.

    PubMed

    Duong, Trac; Lopez, Ivan A; Ishiyama, Akira; Ishiyama, Gail

    2011-01-07

    The basic components of the epithelial, perineural, and perivascular basement membranes in the inner ear have been well-documented in several animal models and in the human inner ear. The von Willebrand A domain-related protein (WARP) is an extracellular matrix molecule with restricted expression in cartilage, and a subset of basement membranes in peripheral nerves, muscle, and central nervous system vasculature. It has been suggested that WARP has an important role in maintaining the blood-brain barrier. To date no studies on WARP distribution have been performed in the inner ear, which is equipped with an intricate vasculature network. In the present study, we determined the distribution of WARP by immunocytochemistry in the human inner ear using auditory and vestibular endorgans microdissected from human temporal bones obtained at autopsy. All subjects (n=5, aged 55-87years old) had documented normal auditory and vestibular function. We also determined the WARP immunolocalization in the mouse inner ear. WARP immunoreactivity localized to the vasculature throughout the stroma of the cristae ampullaris, the maculae utricle, and saccule in the human and mouse. In the human and mouse inner ear, WARP immunoreactivity delineated blood vessels located in the stria vascularis, spiral ligament, sub-basilar region, stromal tissue, and the spiral and vestibular ganglia. The distinct localization of WARP in the inner ear vasculature suggests an important role in maintaining its integrity. In addition, WARP allows delineation of microvessels in the inner ear allowing the study of vascular pathology in the development of otological diseases.

  4. [Report of 2 cases with acquired von Willebrand disease and one with acquired hemophilia A].

    PubMed

    Martínez-Murillo, C; Quintana González, S; Ambriz Fernández, R; Domínguez García, V; Rodríguez Moyado, H; Arias Aranda, A; Collazo Jaloma, J; Gutiérrez Romero, M

    1995-01-01

    We report three patients with acquired inhibitors against F VIII:C/F vW:Ag complex. Two patients had acquired hemophilia A. The three patients presented with bleeding diathesis. Case 1 was a 19 years old woman with Graves-Basedow disease; case 2 was a 40 years old woman with systemic lupus erythematosus of four years; and case 3 a 38 years old woman who had had rheumatoid arthritis for five years and was in her 3d month postpartum. The F VIII:C level was below 8 U/dL in all cases. The F vW:Ag, ristocetin cofactor and platelet aggregation with ristocetin were diminished in the two cases with von Willebrand. Inhibitor to F VIII:C was 50, 38 and 20 Bethesda units, respectively, for cases 1, 2 and 3. The three patients showed clinical response to DDAVP and cryoprecipitates with partial response in laboratory tests. All patients responded to corticosteroid treatment, but immunosuppressive treatment was necessary in case 3.

  5. Actomyosin II contractility expels von Willebrand factor from Weibel-Palade bodies during exocytosis.

    PubMed

    Nightingale, Thomas D; White, Ian J; Doyle, Emily L; Turmaine, Mark; Harrison-Lavoie, Kimberly J; Webb, Kathleen F; Cramer, Louise P; Cutler, Daniel F

    2011-08-22

    The study of actin in regulated exocytosis has a long history with many different results in numerous systems. A major limitation on identifying precise mechanisms has been the paucity of experimental systems in which actin function has been directly assessed alongside granule content release at distinct steps of exocytosis of a single secretory organelle with sufficient spatiotemporal resolution. Using dual-color confocal microscopy and correlative electron microscopy in human endothelial cells, we visually distinguished two sequential steps of secretagogue-stimulated exocytosis: fusion of individual secretory granules (Weibel-Palade bodies [WPBs]) and subsequent expulsion of von Willebrand factor (VWF) content. Based on our observations, we conclude that for fusion, WPBs are released from cellular sites of actin anchorage. However, once fused, a dynamic ring of actin filaments and myosin II forms around the granule, and actomyosin II contractility squeezes VWF content out into the extracellular environment. This study therefore demonstrates how discrete actin cytoskeleton functions within a single cellular system explain actin filament-based prevention and promotion of specific exocytic steps during regulated secretion.

  6. von Willebrand factor contributes to poor outcome in a mouse model of intracerebral haemorrhage

    PubMed Central

    Zhu, Ximin; Cao, Yongliang; Wei, Lixiang; Cai, Ping; Xu, Haochen; Luo, Haiyu; Bai, Xiaofei; Lu, Lu; Liu, Jian-Ren; Fan, Wenying; Zhao, Bing-Qiao

    2016-01-01

    Spontaneous intracerebral haemorrhage (ICH) is the most devastating stroke subtype and has no proven treatment. von Willebrand factor (VWF) has recently been demonstrated to promote inflammation processes. The present study investigated the pathophysiological role of VWF after experimental ICH. Functional outcomes, brain edema, blood-brain barrier (BBB) permeability, cerebral inflammation and levels of intercellular adhesion molecule-1 (ICAM-1) and matrix metalloproteinase-9 (MMP-9) were measured in a mouse model of ICH induced by autologous blood injection. We show that VWF were increased in the plasma and was accumulated in the perihematomal regions of mice subjected to ICH. Injection of VWF resulted in incerased expression of proinflammatory mediators and activation of ICAM-1 and MMP-9, associated with elevated myeloperoxidase, recruitment of neutrophils and microglia. Moreover, mice treated with VWF showed dramatically decreased pericyte coverage, more severe BBB damage and edema formation, and neuronal injury was increased compared with controls. In contrast, blocking antibodies against VWF reduced BBB damage and edema formation and improved neurological function. Together, these data identify a critical role for VWF in cerebral inflammation and BBB damage after ICH. The therapeutic interventions targeting VWF may be a novel strategy to reduce ICH-related injury. PMID:27782211

  7. An explanation for minor multimer species in endothelial cell-synthesized von Willebrand factor.

    PubMed Central

    Lynch, D C; Zimmerman, T S; Ling, E H; Browning, P J

    1986-01-01

    Initial synthesis of von Willebrand factor (vWf) by cultured human endothelial cells proceeds by formation of a dimer of pro-vWf subunits. These subunits are found only within the cell and have an apparent molecular weight of 240,000-260,000, as measured by electrophoresis in sodium dodecyl sulfate-polyacrylamide gels. Posttranslational modifications, including proteolytic cleavage, glycosylation, and sulfation, result in the appearance of two additional vWf subunits. The major one migrates with the subunit of plasma vWf at an apparent molecular weight of 220,000-225,000 and the other migrates more slowly than pro-vWf at an apparent molecular weight of 260,000-275,000. These subunits oligomerize to form a set of vWf multimers, which are subsequently secreted into the culture medium. We isolated individual vWf oligomer species from the agarose gel bands and show that vWf minor, or satellite, species differ from major species in subunit composition. Images PMID:3486890

  8. Successful Ultrasound-Guided Femoral Nerve Blockade and Catheterization in a Patient with Von Willebrand Disease

    PubMed Central

    DiStefano, Youmna E.; Lazar, Michael D.

    2015-01-01

    Peripheral nerve blockade (PNB) is superior to neuraxial anesthesia and/or opioid therapy for perioperative analgesia in total knee replacement (TKR). Evidence on the safety of PNB in patients with coagulopathy is lacking. We describe the first documented account of continuous femoral PNB for perioperative analgesia in a patient with Von Willebrand Disease (vWD). Given her history of opioid tolerance and after an informative discussion, a continuous femoral PNB was planned for in this 34-year-old female undergoing TKR. A Humate-P intravenous infusion was started and the patient was positioned supinely. Using sterile technique with ultrasound guidance, a Contiplex 18 Gauge Tuohy needle was advanced in plane through the fascia iliaca towards the femoral nerve. A nerve catheter was threaded through the needle and secured without complications. Postoperatively, a levobupivacaine femoral catheter infusion was maintained, and twice daily Humate-P intravenous infusions were administered for 48 hours; enoxaparin thromboprophylaxis was initiated thereafter. The patient was discharged uneventfully on postoperative day 4. Given documentation of delayed, unheralded bleeding from PNB in coagulopathic patients, we recommend individualized PNB in vWD patients. Multidisciplinary team involvement is required to guide factor supplementation and thromboprophylaxis, as is close follow-up to elicit signs of bleeding throughout the delayed postoperative period. PMID:26113995

  9. Successful Ultrasound-Guided Femoral Nerve Blockade and Catheterization in a Patient with Von Willebrand Disease.

    PubMed

    DiStefano, Youmna E; Lazar, Michael D

    2015-01-01

    Peripheral nerve blockade (PNB) is superior to neuraxial anesthesia and/or opioid therapy for perioperative analgesia in total knee replacement (TKR). Evidence on the safety of PNB in patients with coagulopathy is lacking. We describe the first documented account of continuous femoral PNB for perioperative analgesia in a patient with Von Willebrand Disease (vWD). Given her history of opioid tolerance and after an informative discussion, a continuous femoral PNB was planned for in this 34-year-old female undergoing TKR. A Humate-P intravenous infusion was started and the patient was positioned supinely. Using sterile technique with ultrasound guidance, a Contiplex 18 Gauge Tuohy needle was advanced in plane through the fascia iliaca towards the femoral nerve. A nerve catheter was threaded through the needle and secured without complications. Postoperatively, a levobupivacaine femoral catheter infusion was maintained, and twice daily Humate-P intravenous infusions were administered for 48 hours; enoxaparin thromboprophylaxis was initiated thereafter. The patient was discharged uneventfully on postoperative day 4. Given documentation of delayed, unheralded bleeding from PNB in coagulopathic patients, we recommend individualized PNB in vWD patients. Multidisciplinary team involvement is required to guide factor supplementation and thromboprophylaxis, as is close follow-up to elicit signs of bleeding throughout the delayed postoperative period.

  10. Evaluation of plasma von Willebrand factor as a biomarker for acute arterial damage in rats.

    PubMed

    Newsholme, S J; Thudium, D T; Gossett, K A; Watson, E S; Schwartz, L W

    2000-01-01

    Plasma von Willebrand factor (vWF) was evaluated as a potential biomarker of acute arterial damage in rats after a vasotoxic dose of the dopaminergic vasodilator, fenoldopam (FP). Male Sprague-Dawley rats were given FP or isotonic saline by subcutaneous injection, and plasma vWF was measured at 2, 6, and 24 hours after challenge. Mean plasma vWF values increased in FP-treated rats compared to controls at 2 hours (167 vs 122%; p < 0.05) and 6 hours postdose (172 vs 130%; p < 0.01) but were comparable to control values after 24 hours. Mesenteric arterial lesions were observed microscopically in all FP-treated rats 24 hours postdose but were not present in rats at 1, 2, 4, 6, or 8 hours after FP challenge. Further, plasma vWF concentrations increased in saline-treated rats after only the minimal perturbation of repeated venipuncture. These results indicate an early, minimal, and transient release of vWF that precedes the onset of morphologically evident vascular damage. The minimal increases in plasma vWF concentrations were of limited predictive value, may be more reflective of an acute-phase reactant response, and were not considered a reliable biomarker of acute FP-induced arterial damage in the rat.

  11. Chitosan scaffold enhances growth factor release in wound healing in von Willebrand disease

    PubMed Central

    Periayah, Mercy Halleluyah; Halim, Ahmad Sukari; Saad, Arman Zaharil Mat; Yaacob, Nik Soriani; Hussein, Abdul Rahim; Karim, Faraizah Abdul; Rashid, Ahmad Hazri Abdul; Ujang, Zanariah

    2015-01-01

    Chitosan-derived biomaterials have been reported to adhere when in contact with blood by encouraging platelets to adhere, activate and aggregate at the sites of vascular injury, thus enhanced wound healing capacity. This study investigated platelet morphology changes and the expression level of transforming growth factor-β1 (TGF-β1) and platelet-derived growth factor-AB (PDGF-AB) in the adherence of two different types of chitosans in von Willebrand disease (vWD): N,O-carboxymethylchitosan (NO-CMC) and oligo-chitosan (O-C). Fourteen vWD voluntary subjects were recruited, and they provided written informed consent. Scanning electron microscopy and enzyme-linked immunosorbent assay test procedures were employed to achieve the objective of the study. The results suggest that the O-C group showed dramatic changes in the platelet’s behaviors. Platelets extended filopodia and generated lamellipodia, leading to the formation of grape-like shaped aggregation. The platelet aggregation occurred depending on the severity of vWD. O-C was bound to platelets on approximately 90% of the surface membrane in vWD type 1; there was 70% and 50% coverage in vWD type II and III, respectively. The O-C chitosan group showed an elevated expression level of TGF-β1 and PDGF-AB. This finding suggests that O-C stimulates these mediators from the activated platelets to the early stage of restoring the damaged cells and tissues. This study demonstrated that the greater expression level of O-C assists in mediating the cytokine complex networks of TGF-β1 and PDGF-AB and induces platelet activities towards wound healing in vWD. With a better understanding of chitosan’s mechanisms of action, researchers are able to accurately develop novel therapies to prevent hemorrhage. PMID:26629055

  12. Redistribution of von Willebrand factor in porcine carotid arteries after balloon angioplasty.

    PubMed

    Giddings, J C; Banning, A P; Ralis, H; Lewis, M J

    1997-10-01

    von Willebrand factor (VWF) is a well-characterized multimeric glycoprotein present in platelets and plasma and synthesized by vascular endothelial cells and megakaryocytes. Its role in platelet-vessel wall interactions has been studied extensively, but its involvement in intravascular events after balloon angioplasty has not been clarified. VWF antigen is not present in porcine arterial endothelium (except for the pulmonary artery) but is readily detected in porcine venous endothelial cells. We have examined the localization of VWF in porcine vessel walls during neointima formation after bilateral carotid balloon-angioplasty. Endothelium was denuded by balloon injury but regenerated by 7 days and was fully confluent by 42 days. VWF was detected at the site of injury in localized, adherent platelet aggregates at 10 minutes after angioplasty that were not present at later time points. A well-demarcated homogeneous layer of VWF was observed on the luminal surface from 30 minutes to day 7, but there was a progressive shift of positive staining from the lumen to the outer media from days 1 to 7. VWF was also strongly detected at sites proximal and distal to the balloon injury from 30 minutes to day 7, although endothelial disruption was minimal and the monolayer remained substantially intact at these sites. Regrowing endothelial cells appeared to contain granular VWF from days 12 to 21, but this was not readily evident at later time points. The results suggest that balloon injury is associated with deposition and medial absorption of plasma or platelet VWF in this porcine model over a time period that precedes and overlaps vascular smooth muscle proliferation and endothelial recoverage. The findings provide evidence to support the concept of a wider role for VWF in tissue injury responses.

  13. Gray platelet syndrome: immunoelectron microscopic localization of fibrinogen and von Willebrand factor in platelets and megakaryocytes.

    PubMed

    Cramer, E M; Vainchenker, W; Vinci, G; Guichard, J; Breton-Gorius, J

    1985-12-01

    An immunogold method was used for investigating the subcellular localization of von Willebrand factor (vWF) and fibrinogen (Fg) in platelets and cultured megakaryocytes from normal subjects and from three patients with the gray platelet syndrome (GPS), a rare congenital disorder characterized by the absence of alpha-granules. In normal platelets at rest, vWF was detected exclusively in alpha-granules, with a characteristic distribution: gold particles were localized at one pole of each labeled granule, outlining the inner face of its membrane. vWF was distributed similarly in the alpha-granules of megakaryocytes at day 12 of culture, where it was also found in small vesicles near the Golgi complex. In contrast, Fg was observed in the whole matrix of all platelet alpha-granules but not in the nucleoids. In platelets from three patients with GPS, vWF and Fg were distributed homogeneously in the rare normal alpha-granules, which could be recognized by their size, and also in small granules identified as abnormal alpha-granules, which were similar in size to the small, possibly immature granules present in normal megakaryocytes. In addition, in some unstimulated platelets, Fg labeling was associated with dense material in the lumen of the surface-connected canalicular system (SCCS). At day 12 of culture, megakaryocytes from the patients with GPS contained some small alpha-granules labeled for Fg and vWF identical to those found in mature platelets. The majority of alpha-granules of normal size appeared partially or completely empty. Thus, we conclude that vWF is distributed differently from Fg in normal alpha-granules, and that unstimulated platelets from patients with GPS contain Fg and vWF in a population of small granules identifiable as abnormal alpha-granules only by immunoelectron microscopy. In addition, the presence of Fg in the SCCS of gray platelets suggests a spontaneous release of the alpha-granule content.

  14. Uncoordinated expression of fibrinogen compared with thrombospondin and von Willebrand factor in maturing human megakaryocytes.

    PubMed

    Cramer, E M; Debili, N; Martin, J F; Gladwin, A M; Breton-Gorius, J; Harrison, P; Savidge, G F; Vainchenker, W

    1989-04-01

    The localization of three known alpha-granule proteins, thrombospondin (TSP), von Willebrand factor (vWF), and fibrinogen (Fg) has been studied in human megakaryocytes (MK) by immunofluorescence and immunoelectron microscopy. For this study, highly purified populations of MK were prepared from human bone marrow either by counterflow centrifugal elutriation or by cell culture from normal subjects and from two patients with megakaryoblastic leukemia. In normal bone marrow immature MK, TSP, and vWF were observed in the Golgi-associated vesicles and in small immature alpha-granules; in mature MK, they were found in the matrix of the mature large alpha-granules. Surprisingly, Fg was detected neither in the Golgi area, nor in the small precursors of alpha-granules; it was only found in the mature alpha-granules but this labeling was generally weaker than in blood platelets. In order to confirm these differences between the expression of Fg and vWF or TSP additional studies were performed on cultured maturing MK: immunofluorescent and ultrastructural immunogold labeling confirmed that vWF appeared early in the maturation while the same immature MK were negative for Fg. In the late maturation stage, the three proteins were detected in the alpha-granules. In order to know whether Fg was lately synthesized or endocytosed from the outside medium, normal MK were grown in the presence of either normal or afibrinogenemic plasma, and normal serum. Fg was detected only in the alpha-granules of MK grown in normal plasma. Similar results were observed with malignant MK, whose maturation was independent of the culture conditions. In conclusion, this study brings immunocytochemical evidence that vWF and TSP are synthesized by immature MK, whereas Fg appears later in the MK alpha-granules and its expression is dependent of the presence of an exogenous Fg source.

  15. Correlation between von Willebrand factor levels and early graft function in clinical liver transplantation.

    PubMed

    Basile, J; Busuttil, A; Sheiner, P A; Emre, S; Guy, S; Schwartz, M E; Boros, P; Miller, C M

    1999-02-01

    Cold preservation/reperfusion leads to sinusoidal endothelial cell (SEC) activation and damage in nearly every liver transplantation; the extent of these changes influences early graft function. Upon reperfusion, activated SEC show increased expression of adhesion molecules, including von Willebrand factor (vWF) which is released into the circulation. This study was designed to evaluate the levels of vWF measured in the caval effluent and correlate these findings with known markers of SEC damage and early graft function. Data were obtained from 35 patients undergoing orthotopic liver transplantation (LTx). Two samples were taken from each patient for measurement of vWF: a) from the portal vein immediately prior to reperfusion; and b) from the first 50 ml of the caval effluent. Commercial assays were used to measure vWF, as well as hyaluronic acid (HA), thrombomodulin (TM), IL-1 beta, IL-6, IL-8 and TNF-alpha. Patients were divided into two groups based on early graft function. Poor early graft function (PEGF) was defined as a peak aspartate transaminase (AST) or alanine transaminase (ALT) level > 2500 U/L during the first three postoperative days (POD) and a prothrombin time (PT) > 16 s on POD 2 (n = 8). The remaining 27 patients had good early graft function (GEGF). In patients with GEGF, vWF levels dropped significantly between the two time points. This change was not observed in those with PEGF. A positive linear correlation was observed in the PEGF group between vWF and HA and IL-6. The different pattern of change in vWF between the two groups, as well as the positive correlation between HA, IL-6 and vWF in PEGF, suggest that vWF may be a useful marker of early graft function.

  16. The oxidative modification of von Willebrand factor is associated with thrombotic angiopathies in diabetes mellitus.

    PubMed

    Oggianu, Laura; Lancellotti, Stefano; Pitocco, Dario; Zaccardi, Francesco; Rizzo, Paola; Martini, Francesca; Ghirlanda, Giovanni; De Cristofaro, Raimondo

    2013-01-01

    The thrombogenic activity of Von Willebrand factor (VWF) is proportional to its molecular size and inversely related to its proteolysis by ADAMTS-13. Oxidation of VWF severely impairs its proteolysis by the metalloprotease. This study was aimed at assessing in patients with type 1 and type 2 diabetes whether protein carbonyls, marker of oxidative stress, are associated with both the level and oxidation status of VWF as well as with micro- and macroangiopathic complications. Eighty-three diabetic patients (41 type 1 and 42 type 2 diabetic subjects) and their respective eighty-three healthy controls were studied after verifying the availability, through institutional databases, of clinical biochemistry records spanning at least 3 years. VWF and protein carbonyls were measured by immunoassays, whereas VWF multimers were studied by SDS-agarose gel electrophoresis. Type 2 diabetic subjects had higher levels of VWF antigen (VWF:ag), VWF activity (VWF:act) and plasma proteins' carbonyls compared to both their controls and type 1 diabetic subjects. Moreover, high molecular weight VWF multimers and specific VWF-bound carbonyls were significantly increased in subjects with micro- and macro-angiopathic complications. In both type 1 and type 2 diabetic subjects, ADAMTS-13 activity was in the normal range. In a multivariable analysis, only VWF-bound carbonyls were significantly associated with any form of thrombotic angiopathy in the entire group of T1- and T2 diabetic patients. These data provide first evidence that not only high VWF levels but also its oxidation status and the presence of high molecular weight VWF multimers that are not observed in SDS-agarose gel electrophoresis of normal subjects are associated with thrombotic angiopathies in diabetes mellitus. These findings may help identify diabetic patients particularly at risk for these complications and elucidate a new pathophysiological mechanism of thrombotic angiopathies in this clinical setting.

  17. The Oxidative Modification of Von Willebrand Factor Is Associated with Thrombotic Angiopathies in Diabetes Mellitus

    PubMed Central

    Pitocco, Dario; Zaccardi, Francesco; Rizzo, Paola; Martini, Francesca; Ghirlanda, Giovanni; De Cristofaro, Raimondo

    2013-01-01

    The thrombogenic activity of Von Willebrand factor (VWF) is proportional to its molecular size and inversely related to its proteolysis by ADAMTS-13. Oxidation of VWF severely impairs its proteolysis by the metalloprotease. This study was aimed at assessing in patients with type 1 and type 2 diabetes whether protein carbonyls, marker of oxidative stress, are associated with both the level and oxidation status of VWF as well as with micro- and macroangiopathic complications. Eighty-three diabetic patients (41 type 1 and 42 type 2 diabetic subjects) and their respective eighty-three healthy controls were studied after verifying the availability, through institutional databases, of clinical biochemistry records spanning at least 3 years. VWF and protein carbonyls were measured by immunoassays, whereas VWF multimers were studied by SDS-agarose gel electrophoresis. Type 2 diabetic subjects had higher levels of VWF antigen (VWF:ag), VWF activity (VWF:act) and plasma proteins’ carbonyls compared to both their controls and type 1 diabetic subjects. Moreover, high molecular weight VWF multimers and specific VWF-bound carbonyls were significantly increased in subjects with micro- and macro-angiopathic complications. In both type 1 and type 2 diabetic subjects, ADAMTS-13 activity was in the normal range. In a multivariable analysis, only VWF-bound carbonyls were significantly associated with any form of thrombotic angiopathy in the entire group of T1- and T2 diabetic patients. These data provide first evidence that not only high VWF levels but also its oxidation status and the presence of high molecular weight VWF multimers that are not observed in SDS-agarose gel electrophoresis of normal subjects are associated with thrombotic angiopathies in diabetes mellitus. These findings may help identify diabetic patients particularly at risk for these complications and elucidate a new pathophysiological mechanism of thrombotic angiopathies in this clinical setting. PMID:23383177

  18. von Willebrand factor multimerization and the polarity of secretory pathways in endothelial cells

    PubMed Central

    Lopes da Silva, Mafalda

    2016-01-01

    The von Willebrand factor (VWF) synthesized and secreted by endothelial cells is central to hemostasis and thrombosis, providing a multifunctional adhesive platform that brings together components needed for these processes. VWF secretion can occur from both apical and basolateral sides of endothelial cells, and from constitutive, basal, and regulated secretory pathways, the latter two via Weibel-Palade bodies (WPB). Although the amount and structure of VWF is crucial to its function, the extent of VWF release, multimerization, and polarity of the 3 secretory pathways have only been addressed separately, and with conflicting results. We set out to clarify these relationships using polarized human umbilical vein endothelial cells (HUVECs) grown on Transwell membranes. We found that regulated secretion of ultra–large (UL)-molecular-weight VWF predominantly occurred apically, consistent with a role in localized platelet capture in the vessel lumen. We found that constitutive secretion of low-molecular-weight (LMW) VWF is targeted basolaterally, toward the subendothelial matrix, using the adaptor protein complex 1 (AP-1), where it may provide the bulk of collagen-bound subendothelial VWF. We also found that basally-secreted VWF is composed of UL-VWF, released continuously from WPBs in the absence of stimuli, and occurs predominantly apically, suggesting this could be the main source of circulating plasma VWF. Together, we provide a unified dataset reporting the amount and multimeric state of VWF secreted from the constitutive, basal, and regulated pathways in polarized HUVECs, and have established a new role for AP-1 in the basolateral constitutive secretion of VWF. PMID:27106123

  19. Functional self-association of von Willebrand factor during platelet adhesion under flow

    NASA Astrophysics Data System (ADS)

    Savage, Brian; Sixma, Jan J.; Ruggeri, Zaverio M.

    2002-01-01

    We have used recombinant wild-type human von Willebrand factor (VWF) and deletion mutants lacking the A1 and A3 domains, as well as specific function-blocking monoclonal antibodies, to demonstrate a functionally relevant self-association at the interface of soluble and surface-bound VWF. Platelets perfused at the wall shear rate of 1,500 s1 over immobilized VWF lacking A1 domain function failed to become tethered to the surface when they were in a plasma-free suspension with erythrocytes, but adhered promptly if soluble VWF with functional A1 domain was added to the cells. The same results were observed when VWF was immobilized onto collagen through its A3 domain and soluble VWF with deleted A3 domain was added to the cells. Thus, VWF bound to glass or collagen sustains a process of homotypic self-association with soluble VWF multimers that, as a result, can mediate platelet adhesion. The latter finding demonstrates that direct immobilization on a substrate is not a strict requirement for VWF binding to platelet glycoprotein Ib. The dynamic and reversible interaction of surface-bound and soluble VWF appears to be specifically homotypic, because immobilized BSA, human fibrinogen, and fibronectin cannot substitute for VWF in the process. Our findings highlight a newly recognized role of circulating VWF in the initiation of platelet adhesion. The self-assembly of VWF multimers on an injured vascular surface may provide a relevant contribution to the arrest of flowing platelets opposing hemodynamic forces, thus facilitating subsequent thrombus growth.

  20. Force-Sensitive Autoinhibition of the von Willebrand Factor Is Mediated by Interdomain Interactions

    PubMed Central

    Aponte-Santamaría, Camilo; Huck, Volker; Posch, Sandra; Bronowska, Agnieszka K.; Grässle, Sandra; Brehm, Maria A.; Obser, Tobias; Schneppenheim, Reinhard; Hinterdorfer, Peter; Schneider, Stefan W.; Baldauf, Carsten; Gräter, Frauke

    2015-01-01

    Von Willebrand factor (VWF) plays a central role in hemostasis. Triggered by shear-stress, it adheres to platelets at sites of vascular injury. Inactivation of VWF has been associated to the shielding of its adhesion sites and proteolytic cleavage. However, the molecular nature of this shielding and its coupling to cleavage under shear-forces in flowing blood remain unknown. In this study, we describe, to our knowledge, a new force-sensory mechanism for VWF-platelet binding, which addresses these questions, based on a combination of molecular dynamics (MD) simulations, atomic force microscopy (AFM), and microfluidic experiments. Our MD simulations demonstrate that the VWF A2 domain targets a specific region at the VWF A1 domain, corresponding to the binding site of the platelet glycoprotein Ibα (GPIbα) receptor, thereby causing its blockage. This implies autoinhibition of the VWF for the binding of platelets mediated by the A1-A2 protein-protein interaction. During force-probe MD simulations, a stretching force dissociated the A1A2 complex, thereby unblocking the GPIbα binding site. Dissociation was found to be coupled to the unfolding of the A2 domain, with dissociation predominantly occurring before exposure of the cleavage site in A2, an observation that is supported by our AFM experiments. This suggests that the A2 domain prevents platelet binding in a force-dependent manner, ensuring that VWF initiates hemostasis before inactivation by proteolytic cleavage. Microfluidic experiments with an A2-deletion VWF mutant resulted in increased platelet binding, corroborating the key autoinhibitory role of the A2 domain within VWF multimers. Overall, autoinhibition of VWF mediated by force-dependent interdomain interactions offers the molecular basis for the shear-sensitive growth of VWF-platelet aggregates, and might be similarly involved in shear-induced VWF self-aggregation and other force-sensing functions in hemostasis. PMID:25954888

  1. Plasmatic ADAMTS-13 metalloprotease and von Willebrand factor in children with cyanotic congenital heart disease

    PubMed Central

    Soares, R.P.S.; Bydlowski, S.P.; Nascimento, N.M.; Thomaz, A.M.; Bastos, E.N.M.; Lopes, A.A.

    2013-01-01

    Changes in plasma von Willebrand factor concentration (VWF:Ag) and ADAMTS-13 activity (the metalloprotease that cleaves VWF physiologically) have been reported in several cardiovascular disorders with prognostic implications. We therefore determined the level of these proteins in the plasma of children with cyanotic congenital heart disease (CCHD) undergoing surgical treatment. Forty-eight children were enrolled (age 0.83 to 7.58 years). Measurements were performed at baseline and 48 h after surgery. ELISA, collagen-binding assays and Western blotting were used to estimate antigenic and biological activities, and proteolysis of VWF multimers. Preoperatively, VWF:Ag and ADAMTS-13 activity were decreased (65 and 71% of normal levels considered as 113 (105-129) U/dL and 91 ± 24% respectively, P < 0.003) and correlated (r = 0.39, P = 0.0064). High molecular weight VWF multimers were not related, suggesting an interaction of VWF with cell membranes, followed by proteolytic cleavage. A low preoperative ADAMTS-13 activity, a longer activated partial thromboplastin time and the need for cardiopulmonary bypass correlated with postoperative bleeding (P < 0.05). Postoperatively, ADAMTS-13 activity increased but less extensively than VWF:Ag (respectively, 2.23 and 2.83 times baseline, P < 0.0001), resulting in an increased VWF:Ag/ADAMTS-13 activity ratio (1.20 to 1.54, respectively, pre- and postoperative median values, P = 0.0029). ADAMTS-13 consumption was further confirmed by decreased ADAMTS-13 antigenic concentration (0.91 ± 0.30 to 0.70 ± 0.25 µg/mL, P < 0.0001) and persistent proteolysis of VWF multimers. We conclude that, in pediatric CCHD, changes in circulating ADAMTS-13 suggest enzyme consumption, associated with abnormal structure and function of VWF. PMID:23558858

  2. Plasma ADAMTS13 activity and von Willebrand Factor Antigen and Activity In Patients with Subarachnoid Hemorrhage

    PubMed Central

    Kumar, Monisha; Cao, Wenjing; McDaniel, Jenny K.; Pham, Huy P.; Raju, Dheeraj; Nawalinski, Kelsey; Frangos, Suzanne; Kung, David; Zager, Eric E.; Kasner, Scott E.; Levine, Joshua M.; Zheng, X. Long

    2017-01-01

    Summary Background Increased von Willebrand factor (VWF) and reduced ADAMTS13 activity are associated with arterial thrombosis. This may also be the culprit mechanism implicated in delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage (SAH). Objective To determine plasma VWF and ADAMTS13 in patients with SAH and healthy subjects; and to explore the levels of those markers and outcome after SAH. Methods 40 consecutive patients were enrolled between September 2007 and April 2014 in a pilot study. Plasma samples were collected from SAH patients on post-bleed day (PBD) 0, 1, 3, 5, 7 and 10 and healthy controls. VWF antigen (VWFAg) and VWF activity (VWFAc) were determined by enzyme-linked immunoassay and collagen binding assay, respectively. ADAMTS13 activity was determined by the cleavage of a fluorescent substrate. Univariate descriptive statistics and cluster analyses were performed based on outcomes in the group with SAH only. Results Mean age of SAH patients was 52.4 years (26–84 years) and 30 (75%) were women. 12/40 (30%) had a high Hunt and Hess grade (IV–V) and 25 (62.5%) were treated with coil embolization. Plasma VWFAg and VWFAc were significantly higher in SAH patients than those in healthy subjects on each PBD (p<0.0001). Concurrently, plasma ADAMTS13 activity in SAH patients was significantly lower than that in healthy subjects (p<0.0001). Among those with SAH, cluster analysis demonstrated that patients with higher VWFAg and VWFAc and/or lower ADAMTS13 activity might be at risk of increased mortality. Conclusions The relative deficiency of plasma ADAMTS13 activity in SAH patients may associate with worse outcome. PMID:28102428

  3. Determinants of bleeding phenotype in adult patients with moderate or severe von Willebrand disease.

    PubMed

    de Wee, Eva M; Sanders, Yvonne V; Mauser-Bunschoten, Eveline P; van der Bom, Johanna G; Degenaar-Dujardin, Manon E L; Eikenboom, Jeroen; de Goede-Bolder, Arja; Laros-van Gorkom, Britta A P; Meijer, Karina; Hamulyák, Karly; Nijziel, Marten R; Fijnvandraat, Karin; Leebeek, Frank W G

    2012-10-01

    We performed a nation-wide cross-sectional study to evaluate determinants of bleeding symptoms in a large unselected cohort of adults with von Willebrand disease (VWD). VWD patients were included (n=664), based on lowest historically measured VWF:Ag and VWF:Act levels ≤30 U/dl. Menorrhagia (85%), cutaneous bleeding (77%), bleeding from minor wounds (77%) and oral-cavity bleeding (62%) occurred most frequently. Higher age was associated with a higher bleeding score (BS), determined according to Tosetto, in females. A 10 year increase in age was associated with 0.8 point (95% confidence interval [CI] 0.4-1.1) higher BS. Females had higher BS than males (median 12 vs. 10, p=0.012). BS differed significantly between VWD type 1, 2 and 3: median 9 (-2-31), 13 (-1-33) and 19.5 (1-35), respectively (p<0.001). BS was strongly associated with VWF and FVIII levels: individuals with VWF:Ag levels ≤10 IU/dl, VWF:Act ≤10 IU/dl and FVIII:C ≤10 IU/dl had, respectively, 5.3 point (95%CI 3.2-7.3), 4.3 point (95%CI 2.9-5.8) and 9.6 point (95%CI 6.5-12.7) higher BS, than those with levels >30 IU/dl. In type 3 patients 1 IU/dl FVIII:C decrease was associated with 0.6 point (95% CI 0.1-1.1) BS increase (p=0.021). In conclusion, in VWD patients the bleeding phenotype is strongly associated with type of VWD and VWF and FVIII levels.

  4. Two Cys residues essential for von Willebrand factor multimer assembly in the Golgi.

    PubMed

    Purvis, Angie R; Gross, Julia; Dang, Luke T; Huang, Ren-Huai; Kapadia, Milan; Townsend, R Reid; Sadler, J Evan

    2007-10-02

    Von Willebrand factor (VWF) dimerizes through C-terminal CK domains, and VWF dimers assemble into multimers in the Golgi by forming intersubunit disulfide bonds between D3 domains. This unusual oxidoreductase reaction requires the VWF propeptide (domains D1D2), which acts as an endogenous pH-dependent chaperone. The cysteines involved in multimer assembly were characterized by using a VWF construct that encodes the N-terminal D1D2D'D3 domains. Modification with thiol-specific reagents demonstrated that secreted D'D3 monomer contained reduced Cys, whereas D'D3 dimer and propeptide did not. Reduced Cys in the D'D3 monomer were alkylated with N-ethylmaleimide and analyzed by mass spectrometry. All 52 Cys within the D'D3 region were observed, and only Cys(1099) and Cys(1142) were modified by N-ethylmaleimide. When introduced into the D1D2D'D3 construct, the mutation C1099A or C1142A markedly impaired the formation of D'D3 dimers, and the double mutation prevented dimerization. In full-length VWF, the mutations C1099A and C1099A/C1142A prevented multimer assembly; the mutation C1142A allowed the formation of almost exclusively dimers, with few tetramers and no multimers larger than hexamers. Therefore, Cys(1099) and Cys(1142) are essential for the oxidoreductase mechanism of VWF multimerization. Cys(1142) is reported to form a Cys(1142)-Cys(1142) intersubunit bond, suggesting that Cys(1099) also participates in a Cys(1099)-Cys(1099) disulfide bond between D3 domains. This arrangement of intersubunit disulfide bonds implies that the dimeric N-terminal D'D3 domains of VWF subunits align in a parallel orientation within VWF multimers.

  5. Increased Von Willebrand factor, decreased ADAMTS13 and thrombocytopenia in melioidosis

    PubMed Central

    Löwenberg, Ester C.; Meijers, Joost C. M.; Maude, Rapeephan R.; Day, Nicholas P. J.; Peacock, Sharon J.; van der Poll, Tom; Wiersinga, W. Joost

    2017-01-01

    Background Melioidosis, caused by bioterror treat agent Burkholderia pseudomallei, is an important cause of community-acquired Gram-negative sepsis in Southeast Asia and Northern Australia. New insights into the pathogenesis of melioidosis may help improve treatment and decrease mortality rates from this dreadful disease. We hypothesized that changes in Von Willebrand factor (VWF) function should occur in melioidosis, based on the presence of endothelial stimulation by endotoxin, pro-inflammatory cytokines and thrombin in melioidosis, and investigated whether this impacted on outcome. Methods/Principal findings We recruited 52 controls and 34 culture-confirmed melioidosis patients at Sappasithiprasong Hospital in Ubon Ratchathani, Thailand. All subjects were diabetic. Platelet counts in melioidosis patients were lower compared to controls (p = 0.0001) and correlated with mortality (p = 0.02). VWF antigen levels were higher in patients (geometric mean, 478 U/dl) compared to controls (166 U/dL, p<0.0001). The high levels of VWF in melioidosis appeared to be due to increased endothelial stimulation (VWF propeptide levels were elevated, p<0.0001) and reduced clearance (ADAMTS13 reduction, p<0.0001). However, VWF antigen levels did not correlate with platelet counts implying that thrombocytopenia in acute melioidosis has an alternative cause. Conclusions/Significance Thrombocytopenia is a key feature of melioidosis and is correlated with mortality. Additionally, excess VWF and ADAMTS13 deficiency are features of acute melioidosis, but are not the primary drivers of thrombocytopenia in melioidosis. Further studies on the role of thrombocytopenia in B. pseudomallei infection are needed. PMID:28296884

  6. ADAMTS13 content in plasma-derived factor VIII/von Willebrand factor concentrates.

    PubMed

    Peyvandi, Flora; Mannucci, Pier M; Valsecchi, Carla; Pontiggia, Silvia; Farina, Claudio; Retzios, Anastassios D

    2013-10-01

    Thrombotic thrombocytopenic purpura (TTP) is a microangiopathy syndrome caused by a congenital or acquired deficiency of ADAMTS13, a plasma metalloprotease that cleaves von Willebrand factor (VWF) and thus prevents the formation of platelet-rich thrombi in the microcirculation. TTP can be fatal if not appropriately and timely treated with the infusion of fresh frozen plasma (FFP) or exchange plasmapheresis, that reverse the process of microangiopathy by removing anti-ADAMTS13 autoantibodies and replacing functional ADAMTS13. The treatment of TTP with FFP is not free from risks and must be administered in hospitals or clinics, owing to the substantial amount of plasma volume infused or exchanged and the frequent need of catheter application. Moreover, most FFPs are not subjected to treatments to remove or inactivate blood-borne infectious agents. A number of recent reports indicate that certain plasma-derived VWF-factor VIII (FVIII) concentrates are clinically effective in the treatment of congenital TTP. In this study, we measured ADAMTS13 levels in various plasma-derived VWF-FVIII concentrates, showing that Koate(®) -DVI (Grifols), contained relatively high amounts of ADAMTS13 and that Alphanate(®) (Grifols) was the closest other product in terms of protease content. Koate(®) -DVI contains, on average (five lots tested), 0.091 ± 0.007 Units of ADAMTS13 activity per IU of FVIII. On the basis of this analysis and other reports of VWF-FVIII concentrate utilization in congenital TTP, potential dosing, and future clinical developments are discussed.

  7. Plasma ADAMTS13 activity and von Willebrand factor antigen and activity in patients with subarachnoid haemorrhage.

    PubMed

    Kumar, Monisha; Cao, Wenjing; McDaniel, Jenny K; Pham, Huy P; Raju, Dheeraj; Nawalinski, Kelsey; Frangos, Suzanne; Kung, David; Zager, Eric; Kasner, Scott E; Levine, Joshua M; Zheng, X Long

    2017-01-19

    Increased von Willebrand factor (VWF) and reduced ADAMTS13 activity are associated with arterial thrombosis. This may also be the culprit mechanism implicated in delayed cerebral ischaemia after aneurysmal subarachnoid haemorrhage (SAH). It was our objective to determine plasma VWF and ADAMTS13 in patients with SAH and healthy subjects; and to explore the levels of those markers and outcome after SAH. Forty consecutive patients were enrolled between September 2007 and April 2014 in a pilot study. Plasma samples were collected from SAH patients on post-bleed day (PBD) 0, 1, 3, 5, 7 and 10 and healthy controls. VWF antigen (VWFAg) and VWF activity (VWFAc) were determined by enzyme-linked immunoassay and collagen binding assay, respectively. ADAMTS13 activity was determined by the cleavage of a fluorescent substrate. Univariate descriptive statistics and cluster analyses were performed based on outcomes in the group with SAH only. Mean age of SAH patients was 52.4 years (26-84 years) and 30 (75 %) were women. 12/40 (30 %) had a high Hunt and Hess grade (IV-V) and 25 (62.5 %) were treated with coil embolisation. Plasma VWFAg and VWFAc were significantly higher in SAH patients than those in healthy subjects on each PBD (p<0.0001). Concurrently, plasma ADAMTS13 activity in SAH patients was significantly lower than that in healthy subjects (p<0.0001). Among those with SAH, cluster analysis demonstrated that patients with higher VWFAg and VWFAc and/or lower ADAMTS13 activity might be at risk of increased mortality. In conclusion, the relative deficiency of plasma ADAMTS13 activity in SAH patients may associate with worse outcome.

  8. Outcomes in Patients With Hemophilia and von Willebrand Disease Undergoing Invasive or Surgical Procedures.

    PubMed

    Chapin, John; Bamme, Jaqueline; Hsu, Fraustina; Christos, Paul; DeSancho, Maria

    2017-03-01

    Adults with hemophilia A (HA), hemophilia B (HB), and von Willebrand disease (VWD) frequently require surgery and invasive procedures. However, there is variability in perioperative management guidelines. We describe our periprocedural outcomes in this setting. A retrospective chart review from January 2006 to December 2012 of patients with HA, HB, and VWD undergoing surgery or invasive procedures was conducted. Type of procedures, management including the use of continuous factor infusion, and administration of antifibrinolytics were reviewed. Adverse outcomes were defined as acute bleeding (<48 hours), delayed bleeding (≥48 hours), transfusion, inhibitor development, and thrombosis. We identified 59 patients with HA and HB. In all, 24 patients had severe hemophilia and 12 had mild/moderate hemophilia. Twelve patients had inhibitors. There were also 5 female carriers of HA and 6 patients with VWD. There were 34 major surgeries (26 orthopedic, 8 nonorthopedic) and 129 minor surgeries. Continuous infusion was used in 55.9% of major surgeries versus 8.5% of minor surgeries. Antifibrinolytics were administered in 14.7% of major surgeries versus 23.2% of minor surgeries. In all, 4 patients developed acute bleeding and 10 patients developed delayed bleeding. Delayed bleeding occurred in 28.6% of genitourinary procedures and in 16.1% of dental procedures. Five patients acquired an inhibitor and 2 had thrombosis. In conclusion, patients with HA, HB, or VWD had similar rates of adverse outcomes when undergoing minor surgeries or major surgeries. This finding underscores the importance of an interdisciplinary management and procedure-specific guidelines for patients with hemophilia and VWD prior to even minor invasive procedures.

  9. Collagen-bound von Willebrand factor has reduced affinity for factor VIII.

    PubMed

    Bendetowicz, A V; Wise, R J; Gilbert, G E

    1999-04-30

    von Willebrand factor (vWf) is a multimeric adhesive glycoprotein that serves as a carrier for factor VIII in plasma. Although each vWf subunit displays a high affinity binding site for factor VIII in vitro, in plasma, only 2% of the vWf sites for factor VIII are occupied. We investigated whether interaction of plasma proteins with vWf or adhesion of vWf to collagen may alter the affinity or availability of factor VIII-binding sites on vWf. When vWf was immobilized on agarose-linked monoclonal antibody, factor VIII bound to vWf with high affinity, and neither the affinity nor binding site availability was influenced by the presence of 50% plasma. Therefore, plasma proteins do not alter the affinity or availability of factor VIII-binding sites. In contrast, when vWf was immobilized on agarose-linked collagen, its affinity for factor VIII was reduced 4-fold, with KD increasing from 0.9 to 3.8 nM. However, one factor VIII-binding site remained available on each vWf subunit. A comparable reduction in affinity for factor VIII was observed when vWf was a constituent of the subendothelial cell matrix and when it was bound to purified type VI collagen. In parallel with the decreased affinity for factor VIII, collagen-bound vWf displayed a 6-fold lower affinity for monoclonal antibody W5-6A, with an epitope composed of residues 78-96 within the factor VIII-binding motif of vWf. We conclude that collagen induces a conformational change within the factor VIII-binding motif of vWf that lowers the affinity for factor VIII.

  10. Pitfalls in Interventional Pain Medicine: Hyponatremia after DDAVP for a Patient with Von Willebrand Disease Undergoing an Epidural Steroid Injection

    PubMed Central

    2017-01-01

    Desmopressin (DDAVP), a synthetic analog of vasopressin, has been used in patients with von Willebrand disease (VWD), mild hemophilia A, and platelet dysfunction to reduce the risk of bleeding associated with surgical and interventional procedures. We report the case of a patient with VWD presenting with a bulging disc and radicular pain that underwent transforaminal epidural steroid injections. Her course was complicated with the interval development of headaches and dizziness symptomatic of moderate hyponatremia, likely due to excessive fluid intake. This report highlights a relatively rare side effect of DDAVP when used for prophylaxis in patients with VWD and reinforces the need for vigilance in these patients. PMID:28392945

  11. Severe von Willebrand disease due to a defect at the level of von Willebrand factor mRNA expression: Detection by exonic PCR-restriction fragment length polymorphism analysis

    SciTech Connect

    Nichols, W.C.; Lyons, S.E.; Harrison, J.S.; Cody, R.L.; Ginsburg, D. )

    1991-05-01

    von Willebrand disease (vWD), the most common inherited bleeding disorder in humans, results from abnormalities in the plasma clotting protein von Willebrand factor (vWF). Severe (type III) vWD is autosomal recessive in inheritance and is associated with extremely low or undetectable vWF levels. The authors report a method designed to distinguish mRNA expression from the two vWF alleles by PCR analysis of peripheral blood platelet RNA using DNA sequence polymorphisms located within exons of the vWF gene. This approach was applied to a severe-vWD pedigree in which three of eight siblings are affected and the parents and additional siblings are clinically normal. Each parent was shown to carry a vWF allele that is silent at the mRNA level. Family members inheriting both abnormal alleles are affected with severe vWD, whereas individuals with only one abnormal allele are asymptomatic. Given the frequencies of the two exon polymorphisms reported here, this analysis should be applicable to {approx}70% of type I and type III vWD patients. This comparative DNA and RNA PCR-restriction fragment length polymorphism approach may also prove useful in identifying defects at the level of gene expression associated with other genetic disorders.

  12. Abnormal VWF modifies megakaryocytopoiesis: studies of platelets and megakaryocyte cultures from patients with von Willebrand disease type 2B.

    PubMed

    Nurden, Paquita; Gobbi, Giuliana; Nurden, Alan; Enouf, Jocelyne; Youlyouz-Marfak, Ibtissam; Carubbi, Cecilia; La Marca, Silvia; Punzo, Margherita; Baronciani, Luciano; De Marco, Luigi; Vitale, Marco; Federici, Augusto B

    2010-04-01

    von Willebrand factor (VWF) is an essential mediator of platelet adhesion to the vessel wall, but little is known about its role in megakaryocytopoiesis. VWF and its platelet receptor, glycoprotein Ibalpha (GPIbalpha), are both expressed during megakaryocyte (MK) maturation. This study was designed to evaluate whether the enhanced VWF-GPIbalpha interactions typical of patients with von Willebrand disease type 2B (VWD2B) modify platelet production. Platelets from 9 patients with VWD2B with 7 different gain-of-function mutations were examined by electron microscopy (EM) and immunofluorescence labeling. For the patients with VWD2B, EM characteristically showed variable numbers of structurally abnormal giant platelets, sometimes in agglutinates. Cultures of MKs from controls performed with or without purified VWF confirmed a positive influence of VWF on platelet production with specific inhibition by an antibody blocking VWF binding to GPIbalpha. VWD2B MK cultures examined by EM showed a disorganized demarcation membrane system and abnormal granule distribution. They produced platelets with structural abnormalities typical of VWD2B. Confocal examination of MK revealed limited extension of pseudopods with few large proplatelets. These results confirm that megakaryocytopoiesis is modified by the enhanced VWF-GPIbalpha interactions. These data obtained for controls and patients with VWD2B suggest a novel regulatory role of VWF-GPIbalpha interactions in platelet production.

  13. Multiple Ligands of von Willebrand Factor-binding Protein (vWbp) Promote Staphylococcus aureus Clot Formation in Human Plasma*

    PubMed Central

    Thomer, Lena; Schneewind, Olaf; Missiakas, Dominique

    2013-01-01

    Staphylococcus aureus secretes coagulase (Coa) and von Willebrand factor-binding protein (vWbp) to activate host prothrombin and form fibrin cables, thereby promoting the establishment of infectious lesions. The D1-D2 domains of Coa and vWbp associate with, and non-proteolytically activate prothrombin. Moreover, Coa encompasses C-terminal tandem repeats for binding to fibrinogen, whereas vWbp has been reported to associate with von Willebrand factor and fibrinogen. Here we used affinity chromatography with non-catalytic Coa and vWbp to identify the ligands for these virulence factors in human plasma. vWbp bound to prothrombin, fibrinogen, fibronectin, and factor XIII, whereas Coa co-purified with prothrombin and fibrinogen. vWbp association with fibrinogen and factor XIII, but not fibronectin, required prothrombin and triggered the non-proteolytic activation of FXIII in vitro. Staphylococcus aureus coagulation of human plasma was associated with the recruitment of prothrombin, FXIII, and fibronectin as well as the formation of cross-linked fibrin. FXIII activity in staphylococcal clots could be attributed to thrombin-dependent proteolytic activation as well as vWbp-mediated non-proteolytic activation of FXIII zymogen. PMID:23960083

  14. O-linked carbohydrate of recombinant von Willebrand factor influences ristocetin-induced binding to platelet glycoprotein 1b.

    PubMed Central

    Carew, J A; Quinn, S M; Stoddart, J H; Lynch, D C

    1992-01-01

    By transfecting the full-length cDNA for human von Willebrand factor (vWf) into a line of Chinese hamster ovary cells with a defect in carbohydrate metabolism, we have prepared recombinant vWf specifically lacking O-linked carbohydrates. We have compared this under-glycosylated protein to fully glycosylated recombinant vWf with respect to several structural and binding properties. vWf deficient in O-linked glycans was synthesized, assembled into multimers, and secreted in an apparently normal manner and was not prone to degradation in the extracellular milieu. It did not differ from fully glycosylated vWf in ability to bind to heparin or to collagen type I but did interact less well with glycoprotein 1b on formalin-fixed platelets. This decreased interaction was evidenced in both a lessened overall binding to platelets and in diminished capacity to promote platelet agglutination, in the presence of ristocetin. In contrast, no difference was seen in platelet binding in the presence of botrocetin. These data indicate a possible role for O-linked carbohydrates in the vWf-glycoprotein 1b interaction promoted by ristocetin and suggest that abnormalities in carbohydrate modification might contribute to the altered ristocetin-dependent reactivity between vWf and platelets described for some variant forms of von Willebrand disease. Images PMID:1469086

  15. Expression of the phenotypic abnormality of platelet-type von Willebrand disease in a recombinant glycoprotein Ib alpha fragment.

    PubMed Central

    Murata, M; Russell, S R; Ruggeri, Z M; Ware, J

    1993-01-01

    The platelet GP Ib-IX receptor supports platelet adhesion and activation by binding to vWf in the exposed subendothelial matrix. An abnormal GP Ib-IX complex exists in platelet-type or pseudo-von Willebrand disease and has a characteristic increased affinity for soluble vWf resulting in impaired hemostatic function due to the removal of larger vWf multimers from the circulation. Genetic studies within an afflicted family have demonstrated that the disease is linked to a Gly233-->Val amino acid substitution within the alpha-subunit of the oligomeric GP Ib-IX complex (Miller, J.L., D. Cunningham, V.A. Lyle, and C. L. Finch. 1991. Proc. Natl. Acad. Sci. USA. 88:4761-4765). To evaluate the functional consequences of this mutation, we constructed a recombinant analogue of the alpha-subunit of GP Ib containing Val233. Experiments comparing molecules with either Gly233 or Val233 revealed that the Val substitution generates a molecule with increased affinity for vWf. The recombinant fragment reproduces the functional abnormality of the GP Ib-IX complex in platelet-type von Willebrand disease, thus establishing the molecular basis of the bleeding disorder within this family. Moreover, it becomes apparent that structural elements responsible for the regulation of hemostasis through modulation of vWf affinity for platelets reside within the alpha-subunit of the GP Ib-IX complex. Images PMID:8486780

  16. Synthesis and secretion of von Willebrand factor and fibronectin in megakaryocytes at different phases of maturation.

    PubMed

    Schick, P K; Walker, J; Profeta, B; Denisova, L; Bennett, V

    1997-04-01

    Our goals have been to define the biochemical characteristics of megakaryocytes during maturation that are critical for platelet assembly and release into the circulation and to introduce biochemical markers for megakaryocytes. To achieve these goals, we have studied fibronectin (FN) and von Willebrand factor (vWF), which are large adhesive proteins that are synthesized by megakaryocytes, stored in alpha granules, and thought to have a fundamental role in hemostasis. The study demonstrated that vWF is primarily synthesized in mature megakaryocytes, which synthesized 7.5 times more vWF than immature megakaryocytes. Brefeldin A, which blocks the exit of proteins from the rough endoplasmic reticulum (RER), inhibited the formation of vWF multimers but did not affect the synthesis of monomers and dimers in mature megakaryocytes. These data are consistent with the formation of vWF dimers in the RER and the assembly of vWF multimers in the trans- and post-golgi. The synthesis of both the 260-kD and 275-kD pro-vWF was detected. However, the synthesis of 275-kD pro-vWF and 220-kD mature vWF was only evident after 2 hours, suggesting that the transit time of nascent vWF through the RER is about 2 hours. Constitutive secretion of vWF was demonstrated in megakaryocytes. About 14.5% and 4.6% of synthesized vWF was secreted by mature and immature megakaryocytes, respectively. In contrast, the synthesis of FN monomers and dimers was established in immature megakaryocytes, and their synthesis in mature megakaryocytes was very similar. Constitutive secretion of FN was not seen in megakaryocytes. Brefeldin A did not inhibit the synthesis of FN dimers; thus, formation of FN dimers occurs in the RER. The demonstration that vWF and FN are synthesized at different phases of megakaryocyte maturation and that only vWF is constitutively secreted by megakaryocytes provides new information relevant to alpha granule formation and possibly bone marrow matrix assembly.

  17. Ets transcription factors bind and transactivate the core promoter of the von Willebrand factor gene.

    PubMed

    Schwachtgen, J L; Janel, N; Barek, L; Duterque-Coquillaud, M; Ghysdael, J; Meyer, D; Kerbiriou-Nabias, D

    1997-12-18

    von Willebrand factor (vWF) gene expression is restricted to endothelial cells and megakaryocytes. Previous results demonstrated that basal transcription of the human vWF gene is mediated through a promoter located between base pairs -89 and +19 (cap site: +1) which is functional in endothelial and non endothelial cells. Two DNA repeats TTTCCTTT correlating with inverted consensus binding sites for the Ets family of transcription factors are present in the -56/-36 sequence. In order to analyse whether these DNA elements are involved in transcription, human umbilical vein endothelial cells (HUVEC), bovine calf pulmonary endothelial cell line (CPAE), HeLa and COS cells were transfected with constructs containing deletions of the -89/+19 fragment, linked to the chloramphenicol acetyl transferase (CAT) reporter gene. The -60/+19 region exhibits significant promoter activity in HUVEC and CPAE cells only. The -42/+19 fragment is not active. Mutations of the -60/+19 promoter fragment in the 5' (-56/-49) Ets binding site abolish transcription in endothelial cells whereas mutations in the 3' (-43/-36) site does not. The -60/-33 fragment forms three complexes with proteins from HUVEC nuclear extracts in electrophoretic mobility shift assay which are dependent on the presence of the 5' Ets binding site. Binding of recombinant Ets-1 protein to the -60/-33 fragment gives a complex which also depends on the 5' site. The -60/+19 vWF gene core promoter is transactivated in HeLa cells by cotransfecting with Ets-1 or Erg (Ets-related gene) expression plasmids. In contrast to the wild type construct, transcription of the 5' site mutants is not increased by these expressed proteins. The results indicate that the promoter activity of the -60/+19 region of the vWF gene depends on transcription factors of the Ets family of which several members like Ets-1, Ets-2 and Erg are expressed in endothelium. Cotransfection of Ets-1 and Erg expression plasmids is sufficient to induce the -60/+19 v

  18. A Drosophila haemocyte-specific protein, hemolectin, similar to human von Willebrand factor.

    PubMed Central

    Goto, A; Kumagai, T; Kumagai, C; Hirose, J; Narita, H; Mori, H; Kadowaki, T; Beck, K; Kitagawa, Y

    2001-01-01

    We identified a novel Drosophila protein of approximately 400 kDa, hemolectin (d-Hml), secreted from haemocyte-derived Kc167 cells. Its 11.7 kbp cDNA contains an open reading frame of 3843 amino acid residues, with conserved domains in von Willebrand factor (VWF), coagulation factor V/VIII and complement factors. The d-hml gene is located on the third chromosome (position 70C1-5) and consists of 26 exons. The major part of d-Hml consists of well-known motifs with the organization: CP1-EG1-CP2-EG2-CP3-VD1-VD2-VD'-VD3-VC1-VD"-VD"'-FC1-FC2-VC2-LA1-VD4-VD5-VC3-VB1-VB2-VC4-VC5-CK1 (CP, complement-control protein domain; EG, epidermal-growth-factor-like domain; VB, VC, VD, VWF type B-, C- and D-like domains; VD', VD", VD"', truncated C-terminal VDs; FC, coagulation factor V/VIII type C domain; LA, low-density-lipoprotein-receptor class A domain; CK, cysteine knot domain). The organization of VD1-VD2-VD'-VD3, essential for VWF to be processed by furin, to bind to coagulation factor VIII and to form interchain disulphide linkages, is conserved. The 400 kDa form of d-Hml was sensitive to acidic cleavage near the boundary between VD2 and VD', where the cleavage site of pro-VWF is located. Agarose-gel electrophoresis of metabolically radiolabelled d-Hml suggested that it is secreted from Kc167 cells mainly as dimers. Resembling VWF, 7.9% (305 residues) of cysteine residues on the d-Hml sequence had well-conserved positions in each motif. Coinciding with the development of phagocytic haemocytes, d-hml transcript was detected in late embryos and larvae. Its low-level expression in adult flies was induced by injury at any position on the body. PMID:11563973

  19. Molecular Imaging of Activated von Willebrand Factor to Detect High-Risk Atherosclerotic Phenotype

    PubMed Central

    McCarty, Owen J. T.; Conley, Robert B.; Shentu, Weihui; Tormoen, Garth W.; Zha, Daogang; Xie, Aris; Qi, Yue; Zhao, Yan; Carr, Chad; Belcik, Todd; Keene, Douglas R.; de Groot, Philip G.; Lindner, Jonathan R.

    2011-01-01

    OBJECTIVES We hypothesized that noninvasive molecular imaging of activated von Willebrand factor (vWF) on the vascular endothelium could be used to detect a high-risk atherosclerotic phenotype. BACKGROUND Platelet-endothelial interactions have been linked to increased inflammatory activation and prothrombotic state in atherosclerosis. These interactions are mediated, in part, by platelet glycoprotein (GP) Ibα, suggesting that dysregulated endothelial vWF is a marker for high-risk atherosclerotic disease. METHODS Microbubbles targeted to activated vWF were prepared by surface conjugation of recombinant GPIbα. Flow-chamber studies were used to evaluate attachment of targeted microbubbles to immobile platelet aggregates bearing activated vWF. Contrast-enhanced ultrasound (CEU) molecular imaging of the aorta from mice was performed: 1) ex vivo after focal crush injury and blood perfusion; and 2) in vivo in mice with advanced atherosclerosis produced by deletion of the low-density lipoprotein receptor and ApoBec-1 editing peptide (LDLR−/−/ApoBec-1−/−). RESULTS In flow-chamber studies, tracer attachment to vWF was >10-fold greater for microbubbles bearing GPIbα compared with control microbubbles (p < 0.01). In the ex vivo aortic injury model, CEU signal enhancement for vWF-targeted microbubbles occurred primarily at the injury site and was 4-fold greater than at noninjured sites (p < 0.05). In LDLR−/−/ApoBec-1−/− mice, inflammatory cell infiltrates and dense vWF expression on the intact endothelium were seen in regions of severe plaque formation. Scanning electron microscopy demonstrated widespread platelet-endothelial interaction and only few sites of endothelial erosion. On CEU, signal enhancement for vWF-targeted microbubbles was approximately 4-fold greater (p < 0.05) in LDLR−/−/ApoBec-1−/− compared with wild-type mice. En face aortic microscopy demonstrated regions where platelet adhesion and microbubble attachment colocalized. CONCLUSIONS

  20. Two distinct forms of Factor VIII coagulant protein in human plasma. Cleavage by thrombin, and differences in coagulant activity and association with von Willebrand factor.

    PubMed Central

    Weinstein, M J; Chute, L E

    1984-01-01

    We have characterized Factor VIII coagulant protein, present in normal human plasma, that reacts with a specific human 125I-labeled anti-human VIII:C antigen Fab antibody fragment. Two major Factor VIII coagulant antigen populations were present. The first, approximately 85% of the total antigen, was bound to von Willebrand factor and when tested in a standard one-stage assay had Factor VIII coagulant activity. The second antigenic population, eluting near fibrinogen when plasma was gel filtered, was not bound to von Willebrand protein, did not have Factor VIII coagulant activity unless activated, but did block anti-VIII:C Fab neutralization of clotting activity. The two antigenic populations were separable by cryoprecipitation and agarose gel electrophoresis. Although the two antigenic populations differed in their Factor VIII coagulant activity and in their binding to von Willebrand factor, the principal member of both populations is of mol wt 2.4 X 10(5). Both antigens, when proteolyzed by thrombin, were quickly converted to a 1 X 10(5)-mol wt form in association with the appearance of VIII:C activity. The 1 X 10(5)-mol wt antigen was further slowly degraded to an 8 X 10(4)-mol wt form while Factor VIII coagulant activity declined. These results demonstrate the presence of an inactive Factor VIII coagulant protein in plasma, not associated with von Willebrand factor, that can react with thrombin to yield Factor VIII coagulant activity. Images PMID:6421875

  1. Circulating and progenitor endothelial cells are abnormal in patients with different types of von Willebrand disease and correlate with markers of angiogenesis.

    PubMed

    Gritti, Giuseppe; Cortelezzi, Agostino; Bucciarelli, Paolo; Rezzonico, Francesca; Lonati, Silvia; La Marca, Silvia; Silvestris, Ilaria; Federici, Augusto B

    2011-08-01

    von Willebrand disease (VWD) is the most common inherited bleeding disorder and is caused by quantitative or qualitative defects of von Willebrand factor (VWF). VWF, synthesized by endothelium and megakaryocytes (MK), circulates in plasma and is present in subendothelium and platelets. Circulating endothelial cells (CEC) and progenitor endothelial cells (EPC) have been recently proposed as markers of peripheral and bone marrow-derived angiogenesis. To evaluate the association of CEC/EPC with known inherited defects of cellular and circulating VWF, we have measured the number of CEC/EPC together with cytokines involved in angiogenesis in different VWD types. A group of 74 patients was composed by the following VWD types: VWD1 (n = 22), VWD2A (n = 9), VWD2B (n = 19), VWD2M (n = 17), and VWD3 (n = 7). Healthy individuals (n = 20) were used as controls. CEC (CD146(+) , CD31(+) , and CD45(-) ) and EPC (CD34(+) , CD133(+) , and CD45(-) ) were evaluated by flow cytometry. Circulating serum levels of VEGF, E-selectin, P-selectin, EPO, and TPO were determined by ELISA. CEC, VEGF, E-selectin, and EPO were higher and EPC lower in VWD patients than in controls (P < 0.01). Among the five groups of VWD patients and controls, a significant difference was found for CEC (one-way ANOVA: P = 0.005), EPC (P = 0.001), E-Selectin (P < 0.0001), EPO (P = 0.021), and TPO (P = 0.004): the latter was high in VWD3 patients. In VWD1, we found an inverse relationship between CEC and VWF:Ag levels (P = 0.048; R(2) = 0.19). Based on these data, CEC are increased in VWD and are associated with the high levels of cytokines involved in angiogenesis (up-regulation). EPC are decreased, suggesting down-regulation of bone marrow-derived angiogenesis in VWD.

  2. Contribution of the collagen binding activity (VWF:CB) in the range of tests for the diagnosis and classification of von Willebrand disease.

    PubMed

    Ferhat-Hamida, Meriem Yasmine; Boukerb, Houda; Hariti, Ghania

    2015-01-01

    Von willebrand disease (VWD) is a common inherited bleeding disorder. The diagnosis may need a large panel of tests that differ in term of sensibility and specificity, and because of the effect of multifactorial modifiers (genetic or environmental); there is difficulty in defining diagnostic limits. We performed a panel of tests on 19 patients suffering from recurrent bleeding, to diagnose and classify VWD subtypes, by introducing the von Willebrand factor (VWF) collagen binding test (VWF:CB), then comparing the results with the activity of VWF risticetin cofactor (VWF:RCo) and multimer pattern. We considered 30% limit rate of VWF, as described by many authors, to make the diagnosis of VWD. The diagnosis of type 1 of VWD has been confirmed in 7patients, subtype 2A in 2 patients, subtype 2M in 2 patients and type 3 in 2 patients. We also defined a new group of 6 patients named "uncertain type 1" that didn't fill into the type 1 diagnostic criterion. The comparison between VWF:CB and VWF:RCo showed good correlation for all types of VWD except for type 2 while comparison between VWF:CB and multimer pattern showed good concordance for all types of VWD diagnosed. In conclusion, VWF:CB can be a good alternative to VWF:RCo for the diagnosis of quantitative deficiencies of VWF. It can also replace the multimer pattern study. However, the introduction of VWF:CB didn't help in the diagnosis of the "uncertain type 1" group of patients and cannot be a replacement for qualitative defect.

  3. A novel platelet-type von Willebrand disease mutation (GP1BA p.Met255Ile) associated with type 2B "Malmö/New York" von Willebrand disease.

    PubMed

    Lavenu-Bombled, Cécile; Guitton, Corinne; Dupuis, Arnaud; Baas, Marie-Jeanne; Desconclois, Céline; Dreyfus, Marie; Li, Renhao; Caron, Claudine; Gachet, Christian; Fressinaud, Edith; Lanza, François

    2016-11-30

    Interaction between von Willebrand factor (VWF) and platelet GPIbα is required for primary haemostasis. Lack or loss-of-function in the ligand-receptor pair results in bleeding complications. Paradoxically, gain-of-function mutations in VWF or GPIbα also result in bleeding complications as observed in type 2B von Willebrand disease (VWD) and platelet-type- (PT-) VWD, respectively. A similar phenotype is observed with increased ristocetin-induced platelet agglutination and disappearance of the highest molecular weight multimers of VWF. We evaluated a patient with a bleeding disorder and a biological presentation compatible with type 2B VWD. VWF and platelet functional assays, sequencing of the VWF and GP1BA genes, and expression studies in HEK cells were performed. Sequencing of the VWF gene in the propositus revealed a heterozygous p.Pro1266Leu mutation previously found in type 2B VWD Malmö/New York. These variants are characterised by a mild phenotype and a normal VWF multimer composition suggesting the presence of a second mutation in our propositus. Sequencing of the GP1BA gene revealed a heterozygous c.765G>A substitution changing Met at position 255 of GPIbα to Ile. This new mutation is located in the β-switch domain where five other gain-of-function mutations have been reported in PT-VWD. Expression of GPIbα Ile255 in HEK GPIb-IX cells resulted in enhanced VWF binding compared to wild-type, similar to known PT-VWD mutations (p.Val249, p.Ser249 and p.Val255) indicating that it contributes to the propositus defects. This first report associating PT- with type 2B VWD illustrates the importance of combining biological assays with genetic testing to better understand the clinical phenotype.

  4. Efficacy and safety of a new generation von Willebrand factor/factor VIII concentrate (Wilate®) in the management of perioperative haemostasis in von Willebrand disease patients undergoing surgery.

    PubMed

    Windyga, J; von Depka-Prondzinski, M

    2011-06-01

    The aim of this study was to assess the efficacy of Wilate®, a new generation, plasma-derived, high-purity, double virus-inactivated von Willebrand factor (VWF) and factor VIII (FVIII) concentrate (ratio close to physiological 1:1) in the perioperative management of haemostasis in von Willebrand disease (VWD). Data for VWD patients who received Wilate® for perioperative management were obtained from four European, prospective, open-label, non-controlled, non-randomised, multicentre phase II or III clinical trials. A total of 57 surgical procedures were performed (major: n = 27; minor n = 30) in 32 patients. The majority of patients (n = 19, 59.4%) had type 3 VWD, 9 (28.1%) had type 2 VWD and four (12.5%) had type 1 VWD. During major surgery, median daily FVIII dose and mean number of infusions were 25 IU•kg-1 FVIII (VWF:RCo ~23 IU•kg-1) and 11.0, respectively. Corresponding values for minor surgery were 35 IU•kg-1 (VWF:RCo ~32 IU•kg-1) and 1.5. The efficacy of Wilate® was rated by the investigator as excellent or good in 51 of 53 (96%) procedures. Tolerability was rated as very good or good in 100% of major surgeries (27 of 27) and minor surgeries (29 of 29). Wilate® is an effective and well-tolerated VWF/FVIII replacement therapy in the perioperative management of haemostasis in patients with VWD. It can be administered at a similar FVIII dose, but at a lower VWF dose, as compared to older generation products. Clinical benefits were shown in a population with a high proportion of type 3 VWD patients.

  5. Use of monoclonal antibody and colloidal gold in E.M. localization of von Willebrand factor in megakaryocytes and platelets.

    PubMed

    Jeanneau, C; Avner, P; Sultan, Y

    1984-10-01

    The subcellular localization of Factor VIII/von Willebrand protein (VIII R:Ag) is studied with monoclonal antibody and gold immunocytochemical technique. Monoclonal antibody against purified VIII R:Ag is brightly fluorescent on megakaryocytes and platelets. In E.M., gold immunolabeling is performed on thin cell sections of human megakaryocytes and platelets. Different embedding materials are used to preserve the antigenicity : Epon embedded megakaryocytes show a high concentration of VIII R:Ag in alpha-granules using 4F9 monoclonal antibody. In comparison, lowicryl K4M embedded material does not improve the same specificity, only a few platelets granules were stained. This subcellular localization, in full agreement with biochemical results appears visualized for the first time in E.M.

  6. Abnormal platelet von Willebrand factor (vWF) as a marker of abnormal function in megakaryocytic dysplasia.

    PubMed

    de Cataldo, F; Baudo, F; Redaelli, R; Corno, A R

    1995-03-01

    The myelodysplastic syndromes (MDS) are neoplastic disorders of the hemopoietic system; multilineage involvement is also evidenced by specific cellular dysfunctions. The von Willebrand factor (vWF), synthesized and processed in the megakaryocytes (MK), is stored in the alpha granules of the platelets. The platelet vWF multimeric pattern was studied in 18 patients with MDS, and in 4 with pernicious anemia (PA), to investigate whether the processing of vWF is abnormal in the megakaryocytic dysplasia. An abnormal multimeric pattern was observed in 10/18 MDS and 4/4 PA patients. The abnormality of this specific protein is the discrete expression of the basic disorder, and is reversible when hemopoiesis is normalized. Although the data do not allow any conclusion, abnormal synthesis is the likely explantation of the abnormality.

  7. Salvage therapy with high dose Intravenous Immunoglobulins in acquired Von Willebrand Syndrome and unresponsive severe intestinal bleeding

    PubMed Central

    2014-01-01

    A 91-year-old woman affected with acquired Von Willebrand (VW) syndrome and intestinal angiodysplasias presented with severe gastrointestinal bleeding (hemoglobin 5 g/dl). Despite replacement therapy with VW factor/factor VIII concentrate qid, bleeding did not stop (eleven packed red blood cell units were transfused over three days). High circulating levels of anti-VW factor immunoglobulin M were documented immunoenzimatically. Heart ultrasound showed abnormalities of the mitral and aortic valves with severe flow alterations. When intravenous immunoglobulins were added to therapy, prompt clinical and laboratory responses occurred: complete cessation of bleeding, raise in hemoglobin, VW factor antigen, VW ristocetin cofactor and factor VIII levels as well as progressive reduction of the anti-VWF autoantibody levels. PMID:24926417

  8. Evaluation of von Willebrand factor phenotypes and genotypes in Hemophilia A patients with and without identified F8 mutations

    PubMed Central

    Boylan, Brian; Rice, Anne S.; De Staercke, Christine; Eyster, M. Elaine; Yaish, Hassan M.; Knoll, Christine M.; Bean, Christopher J.; Miller, Connie H.

    2015-01-01

    Summary Background Hemophilia A (HA) is an X-linked bleeding disorder caused by a deficiency in factor VIII (FVIII). von Willebrand disease (VWD) is characterized by a quantitative or qualitative defect in von Willebrand Factor (VWF). Patients with VWD with severely low VWF or VWD Type 2N (VWD2N), a VWD subtype distinguished by defective VWF binding to FVIII, may have reduced FVIII levels secondary to their VWD. These patients superficially resemble patients with HA, and pose a potential for misdiagnosis. Objectives Investigate the unexplained cause of bleeding in HA patients without known FVIII mutations by assessing plasma VWF antigen (VWF:Ag), FVIII binding capacities, and VWF genotypes. Patients/Methods Thirty-seven of 1027 patients with HA studied as part of the Hemophilia Inhibitor Research Study lacked identifiable F8 mutations. These patients (cases) and 73 patients with identified F8 mutations (controls) were evaluated for VWF:Ag, patient's VWF capacity to bind FVIII (VWF:FVIIIB), and VWF sequence. Results Four cases had VWF:Ag <3 IU/dL and VWF mutations consistent with Type3 VWD. Six cases and one control were heterozygous for mutations previously reported to cause Type1 VWD (VWD1) (n=5 cases and 1 control) or predicted to be deleterious by Polyphen2 and SIFT prediction tools (n=1 case). One control had VWF:Ag <30 IU/dl, and seven patients (4 cases and 3 controls), including two cases who were heterozygous for a known VWD2N mutation, had reduced VWF:FVIIIB. Conclusions These data emphasize that some patients diagnosed with HA require VWF assessments in order to achieve a comprehensive diagnosis and an optimal treatment strategy. PMID:25780857

  9. von Willebrand Factor-Rich Platelet Thrombi in the Liver Cause Sinusoidal Obstruction Syndrome following Oxaliplatin-Based Chemotherapy

    PubMed Central

    Nishigori, Naoto; Matsumoto, Masanori; Koyama, Fumikazu; Hayakawa, Masaki; Hatakeyayama, Kinta; Ko, Saiho; Fujimura, Yoshihiro; Nakajima, Yoshiyuki

    2015-01-01

    Oxaliplatin-based chemotherapy is widely used to treat advanced colorectal cancer (CRC). Sinusoidal obstruction syndrome (SOS) due to oxaliplatin is a serious type of chemotherapy-associated liver injury (CALI) in CRC patients. SOS is thought to be caused by the sinusoidal endothelial cell damage, which results in the release of unusually-large von Willebrand factor multimers (UL-VWFMs) from endothelial cells. To investigate the pathophysiology of CALI after oxaliplatin-based chemotherapy, we analyzed plasma concentration of von Willebrand factor (VWF) and the distribution of VWFMs in CRC patients. Twenty-three patients with advanced CRC who received oxaliplatin-based chemotherapy with (n = 6) and without (n = 17) bevacizumab were analyzed. CALI (n = 6) and splenomegaly (n = 9) were found only in patients who did not treated with bevacizumab. Plasma VWF antigen (VWF:Ag) and serum aspartate aminotransferase (AST) levels increased after chemotherapy only in patients without bevacizumab. VWFM analysis in patients who did not receive bevacizumab showed the presence of UL-VWFMs and absence of high molecular weight VWFMs during chemotherapy, especially in those with CALI. In addition, plasma VWF:Ag and AST levels increased after chemotherapy in patients with splenomegaly (n = 9), but not in patients without splenomegaly (n = 14). Histological findings in the liver tissue of patients who did not receive bevacizumab included sinusoidal dilatation and microthrombi in the sinusoids. Many microthrombi were positive for both anti-IIb/IIIa and anti-VWF antibodies. Plasma UL-VWFM levels might be increased by damage to endothelial cells as a result of oxaliplatin-based chemotherapy. Bevacizumab could prevent CALI and splenomegaly through inhibition of VWF-rich platelet thrombus formation. PMID:26580395

  10. A genetically-engineered von Willebrand disease type 2B mouse model displays defects in hemostasis and inflammation

    PubMed Central

    Adam, Frédéric; Casari, Caterina; Prévost, Nicolas; Kauskot, Alexandre; Loubière, Cécile; Legendre, Paulette; Repérant, Christelle; Baruch, Dominique; Rosa, Jean-Philippe; Bryckaert, Marijke; de Groot, Philip G.; Christophe, Olivier D.; Lenting, Peter J.; Denis, Cécile V.

    2016-01-01

    von Willebrand disease (VWD)-type 2B is characterized by gain-of-function mutations in the von Willebrand factor (VWF) A1-domain, leading to increased affinity for its platelet-receptor, glycoprotein Ibα. We engineered the first knock-in (KI) murine model for VWD-type 2B by introducing the p.V1316M mutation in murine VWF. Homozygous KI-mice replicated human VWD-type 2B with macrothrombocytopenia (platelet counts reduced by 55%, platelet volume increased by 44%), circulating platelet-aggregates and a severe bleeding tendency. Also, vessel occlusion was deficient in the FeCl3-induced thrombosis model. Platelet aggregation induced by thrombin or collagen was defective for KI-mice at all doses. KI-mice manifested a loss of high molecular weight multimers and increased multimer degradation. In a model of VWF-string formation, the number of platelets/string and string-lifetime were surprisingly enhanced in KI-mice, suggesting that proteolysis of VWF/p.V1316M is differentially regulated in the circulation versus the endothelial surface. Furthermore, we observed increased leukocyte recruitment during an inflammatory response induced by the reverse passive Arthus reaction. This points to an active role of VWF/p.V1316M in the exfiltration of leukocytes under inflammatory conditions. In conclusion, our genetically-engineered VWD-type 2B mice represent an original model to study the consequences of spontaneous VWF-platelet interactions and the physiopathology of this human disease. PMID:27212476

  11. Bleeding spectrum in children with moderate or severe von Willebrand disease: Relevance of pediatric-specific bleeding.

    PubMed

    Sanders, Yvonne V; Fijnvandraat, Karin; Boender, Johan; Mauser-Bunschoten, Evelien P; van der Bom, Johanna G; de Meris, Joke; Smiers, Frans J; Granzen, Bernd; Brons, Paul; Tamminga, Rienk Y J; Cnossen, Marjon H; Leebeek, Frank W G

    2015-12-01

    The bleeding phenotype of children with von Willebrand disease (VWD) needs to be characterized in detail to facilitate diagnosis during childhood and aid in the planning and assessment of treatment strategies. The objective was to evaluate the occurrence, type, and severity of bleeding in a large cohort of children with moderate and severe VWD. We included 113 children (aged 0-16 years) with Type 1 (n = 60), 2 (n = 44), and 3 (n = 9) VWD with von Willebrand factor (VWF) antigen and/or VWF ristocetin cofactor levels ≤ 30 U/dL from a nation-wide cross-sectional study ("Willebrand in the Netherlands" study). Bleeding severity and frequency were determined using the International Society on Thrombosis and Hemostasis-Bleeding Assessment Tool (ISTH-BAT) with supplementary pediatric-specific bleeding symptoms (umbilical stump bleeding, cephalohematoma, cheek hematoma, conjunctival bleeding, postcircumcision and postvenipuncture bleeding). We found that all 26 postmenarche girls experienced menorrhagia. Other common bleedings were cutaneous (81%), oropharyngeal (64%), prolonged bleeding from minor wounds (58%), and epistaxis (56%). Pediatric-specific bleeding symptoms were present in 44% of patients. ISTH-BAT bleeding score was higher in index cases than in affected family members (median, 12.0 vs. 6.5, P < 0.001), higher in Type 3 VWD than in Type 2 or 1 (17.0 vs. 10.5 or 6.5, P < 0.001) and higher in children with severe (<10 U/dL) than moderate VWD (10-30 U/dL) (11.0 vs. 7.0, P < 0.001). Frequency of any bleeding, epistaxis, and oral cavity was higher in types 2 and 3 than in Type 1 VWD and was associated with VWF levels. We conclude that pediatric-specific bleeding symptoms occurred in a large proportion of children with moderate or severe VWD and should be included when evaluating children for VWD.

  12. Acquired von Willebrand syndrome in a case of polycythemia vera resulting in recurrent and massive bleeding events in the pleural and abdominal cavity.

    PubMed

    Duan, Yanchao; Nie, Jing; Zhang, Zhirong; Ji, Chunyan

    2015-01-01

    A 52-year-old woman was admitted to the hospital three times in a span of 5 years in hypovolemic shock because of spontaneous and massive bleeding in the pleural and abdominal cavity. Blood tests revealed a high number of blood cells, and bone marrow smears showed trilineage myeloproliferation. Serum erythropoietin level was decreased. Analysis revealed a V617F mutation in the JAK2 protein. Her activated partial thromboplastin time was slightly prolonged, the ratio between von Willebrand factor (vWF) propeptide and vWF antigen was in the normal range, but the ratio between vWF and ristocetin cofactor was decreased dramatically. Further investigation revealed the absence of large and intermediate vWF-multimers. She was diagnosed with polycythemia vera with acquired von Willebrand syndrome. The bleeding was stopped using a transfusion of freshly thawed plasma and cryoprecipitate.

  13. [Relation of socioeconomic levels and life style to fibrinogen and von Willebrand factor in healthy Venezuelans and those with ischemic cardiopathy].

    PubMed

    Rodríguez-Larralde, Alvaro; Mijares, Mercedes E; Nagy, Elena; Espinosa, Raul; Ryder, Elena; Diez-Ewald, María P; Torres, Enrique; Coll-Sangrona, Enriqueta; Rodríguez-Roa, Elsy; Carvajal, Zoila; Lundberg, Ulf; Campos, Gilberto; Gill, Amparo; Arocha-Piñango, Carmen L

    2005-06-01

    Previous studies in Europe, U.S.A and Japan have revealed an inverse relationship between socioeconomic levels and fibrinogen concentration. Similar results have been reported in a smaller number of studies for concentrations of von Willebrand factor. In this opportunity we present results on the relationship between smoking, drinking, physical activity, age and socioeconomic level on fibrinogen and von Willebrand factor concentrations in a Venezuelan sample. The control population consisted of 978 men and 968 women. Patients with coronary heart disease were 172 males and 78 females. The presence of one or more of the following conditions: smoking or less than 5 years of having quit, non drinkers or drinking in excess, and a reduced physical activity, was considered a health related risk factor for high levels of these two haemostatic variables. Our results indicate that in Controls, the socioeconomic level had a significant effect on fibrinogen and von Willebrand factor levels, only in women: those of lower socioeconomic levels had the highest concentrations. This difference was maintained when age was taken into account. Health related behaviors had no significant effect on either variable. In patients, age had no effect on either variable. The health behavior risk factor had a significant effect only on fibrinogen of male patients, and socioeconomic level had a significant effect only on the fibrinogen of female patients. More studies in Venezuela are recommended, in order to increase our knowledge on the relationship between socioeconomic levels, haemostatic markers and the occurrence of coronary heart disease.

  14. Severe transfuse related acute lung injury (TRALI) syndrome in a 14 years old girl with a history of type I von Willebrand disease.

    PubMed

    Arghir, Oana C; Ionescu, Florin C; Apostol, Adriana

    2012-01-01

    Von Willebrand disease (vWD) is the most common inherited bleeding disorder based on an autosomal abnormality of von Willebrand factor. Transfusion is a lifesaving medical intervention among patients with bleeding disorders. Patients with vWD are exposed to Transfuse Related Acute Lung Injury (TRALI) when they become recipients of multiple blood products and repeated transfusions. TRALI is a non-hemolytic transfusion reaction induced by infusions of intravenous immunoglobulin, platelets (suspended in plasma), whole blood, cryoprecipitates, and fresh frozen plasma (FFP). We report a 14 years old white girl, with a history of type 1 von Willebrand disease (vWd), recipient of 2 units' fresh-frozen plasma (FFP) and 1 unit whole blood transfusion who developed an acute respiratory distress with severe hypoxemia and bilateral pulmonary infiltrate on chest X-ray within 3 hours of the whole blood transfusion, completely reversible after mechanical ventilation. Concluding, patients with vWd who received recurrent transfusions have an increased risk of TRALI. Physicians must be familiar with it as a cause of white lung X-ray pattern.

  15. A Laboratory Phenotype/Genotype Correlation of 1167 French Patients From 670 Families With von Willebrand Disease: A New Epidemiologic Picture.

    PubMed

    Veyradier, Agnès; Boisseau, Pierre; Fressinaud, Edith; Caron, Claudine; Ternisien, Catherine; Giraud, Mathilde; Zawadzki, Christophe; Trossaert, Marc; Itzhar-Baïkian, Nathalie; Dreyfus, Marie; d'Oiron, Roseline; Borel-Derlon, Annie; Susen, Sophie; Bezieau, Stéphane; Denis, Cécile V; Goudemand, Jenny

    2016-03-01

    von Willebrand disease (VWD) is a genetic bleeding disease due to a defect of von Willebrand factor (VWF), a glycoprotein crucial for platelet adhesion to the subendothelium after vascular injury. VWD include quantitative defects of VWF, either partial (type 1 with VWF levels <50 IU/dL) or virtually total (type 3 with undetectable VWF levels) and also qualitative defects of VWF (type 2 variants with discrepant antigenic and functional VWF levels). The most bleeding forms of VWD usually do not concern type 1 patients with the mildest VWF defects (VWF levels between 30 and 50 IU/dL). The French reference center for VWD performed a laboratory phenotypic and genotypic analysis in 1167 VWD patients (670 families) selected by their basic biologic phenotype: type 3, type 2, and type 1 with VWF levels <30 IU/dL. In these patients indeed, to achieve an accurate diagnosis of VWD type and subtype is crucial for the management (treatment and genetic counseling). A phenotype/genotype correlation was present in 99.3% of cases; 323 distinct VWF sequence variations (58% of novel) were identified (missense 67% versus truncating 33%). The distribution of VWD types was: 25% of type 1, 8% of type 3, 66% of type 2 (2A: 18%, 2B: 17%, 2M: 19%, 2N: 12%), and 1% of undetermined type. Type 1 VWD was related either to a defective synthesis/secretion or to an accelerated clearance of VWF. In type 3 VWD, bi-allelic mutations of VWF were found in almost all patients. In type 2A, the most frequent mechanism was a hyper-proteolysis of VWF. Type 2B showed 85% of patients with deleterious mutations (distinct from type 2B New York). Type 2M was linked to a defective binding of VWF to platelet glycoprotein Ib or to collagen. Type 2N VWD included almost half type 2N/3. This biologic study emphasizes the complex mechanisms for both quantitative and qualitative VWF defects in VWD. In addition, this study provides a new epidemiologic picture of the most bleeding forms of VWD in which qualitative

  16. Similarity in joint and mucous bleeding syndromes in type 2N von Willebrand disease and severe hemophilia A coexisting with type 1 von Willebrand disease in two Chinese pedigrees.

    PubMed

    Qin, H H; Xing, Z F; Wang, X F; Ding, Q L; Xi, X D; Wang, H L

    2014-04-01

    In this study, we investigated the molecular basis of two unrelated Chinese patients with hemostatic disorders. The proband of the first family had severe hemophilia A (HA) coexisting with type 1 von Willebrand disease (VWD) and the proband of the second family had type 2N VWD. Both probands had similar phenotypes, which included joint and mucosal bleeding, very low factor VIII (FVIII) activity (FVIII:C), and moderate reductions in VWF antigen (VWF:Ag) and VWF ristocetin cofactor activity (VWF:Rco), as well as a normal multimeric pattern. One FVIII mutation and three VWF mutations were identified: FVIII p.R446* and VWF heterozygous p.E216K mutations were detected in proband 1 and compound heterozygosity of VWF mutations (p.R816W and c.1911delC) in proband 2. Transient expression studies in HEK293T cells proved that R816W mutation abolished the binding of FVIII to VWF and slightly impaired protein synthesis and secretion; 1911delC mutation mainly impaired VWF protein synthesis and secretion. These results provided insight into the possible pathogenic mechanism of type 2N VWD in Chinese patients carrying these mutations.

  17. Von Willebrand Factor, ADAMTS13 and D-Dimer Are Correlated with Different Levels of Nephropathy in Type 1 Diabetes Mellitus

    PubMed Central

    Domingueti, Caroline Pereira; Dusse, Luci Maria S.; Fóscolo, Rodrigo Bastos; Reis, Janice Sepúlveda; Annichino-Bizzacchi, Joyce Maria; Orsi, Fernanda Loureiro de Andrade; Mazetto, Bruna de Moraes; Carvalho, Maria das Graças; Gomes, Karina Braga; Fernandes, Ana Paula

    2015-01-01

    We have investigated whether von Willebrand factor, ADAMTS13 (a disintegrin and metalloproteinase with thrombospondin type 1 motif, member 13), and D-Dimer were associated with different levels of renal function in patients with type 1 diabetes. Patients were classified according to level of renal function through estimated glomerular filtration rate: ≥90 and <130mL/min/1,73m2, n=52 (control group), ≥60 and <90mL/min/1,73m2, n=29 (mild renal dysfunction group), <60mL/min/1,73m2, n=28 (severe renal dysfunction group); and through urinary albumin excretion: normoalbuminuria, microalbuminuria and macroalbuminuria. Von Willebrand factor, ADAMTS13, and D-Dimer plasma levels were determined by enzyme-linked immunosorbent assay. ADAMTS13 activity was determined by fluorescence resonance energy transfer assay. Von Willebrand factor levels were increased in patients with mild (P=0.001) and severe (P<0.001) renal dysfunction as compared to the control group. ADAMTS13 levels were also increased in mild (P=0.029) and severe (P=0.002) renal dysfunction groups in comparison to the control group, while ADAMTS13 activity was increased only in the severe renal dysfunction group as compared to the control group (P=0.006). No significant differences were observed among the groups regarding von Willebrand factor/ADAMTS13 ratio. ADAMTS13 activity/ADAMTS13 levels ratio was reduced in patients with mild (P=0.013) and severe (P=0.015) renal dysfunction as compared to the control group. D-Dimer levels were increased in patients with mild (P=0.006) and severe (P<0.001) renal dysfunction as compared to the control group; it was also higher in patients with severe renal dysfunction as compared to the mild renal dysfunction group (P=0.019). Similar results were found for albuminuria classification. Increased von Willebrand factor, ADAMTS13, and D-Dimer levels and decreased ADAMTS13 activity/ADAMTS13 levels ratio are associated with renal dysfunction in patients with type 1 diabetes

  18. Identification and Characterization of Novel Variations in Platelet G-Protein Coupled Receptor (GPCR) Genes in Patients Historically Diagnosed with Type 1 von Willebrand Disease.

    PubMed

    Stockley, Jacqueline; Nisar, Shaista P; Leo, Vincenzo C; Sabi, Essa; Cunningham, Margaret R; Eikenboom, Jeroen C; Lethagen, Stefan; Schneppenheim, Reinhard; Goodeve, Anne C; Watson, Steve P; Mundell, Stuart J; Daly, Martina E

    2015-01-01

    The clinical expression of type 1 von Willebrand disease may be modified by co-inheritance of other mild bleeding diatheses. We previously showed that mutations in the platelet P2Y12 ADP receptor gene (P2RY12) could contribute to the bleeding phenotype in patients with type 1 von Willebrand disease. Here we investigated whether variations in platelet G protein-coupled receptor genes other than P2RY12 also contributed to the bleeding phenotype. Platelet G protein-coupled receptor genes P2RY1, F2R, F2RL3, TBXA2R and PTGIR were sequenced in 146 index cases with type 1 von Willebrand disease and the potential effects of identified single nucleotide variations were assessed using in silico methods and heterologous expression analysis. Seven heterozygous single nucleotide variations were identified in 8 index cases. Two single nucleotide variations were detected in F2R; a novel c.-67G>C transversion which reduced F2R transcriptional activity and a rare c.1063C>T transition predicting a p.L355F substitution which did not interfere with PAR1 expression or signalling. Two synonymous single nucleotide variations were identified in F2RL3 (c.402C>G, p.A134 =; c.1029 G>C p.V343 =), both of which introduced less commonly used codons and were predicted to be deleterious, though neither of them affected PAR4 receptor expression. A third single nucleotide variation in F2RL3 (c.65 C>A; p.T22N) was co-inherited with a synonymous single nucleotide variation in TBXA2R (c.6680 C>T, p.S218 =). Expression and signalling of the p.T22N PAR4 variant was similar to wild-type, while the TBXA2R variation introduced a cryptic splice site that was predicted to cause premature termination of protein translation. The enrichment of single nucleotide variations in G protein-coupled receptor genes among type 1 von Willebrand disease patients supports the view of type 1 von Willebrand disease as a polygenic disorder.

  19. Von Willebrand Factor, ADAMTS13 and D-Dimer Are Correlated with Different Levels of Nephropathy in Type 1 Diabetes Mellitus.

    PubMed

    Domingueti, Caroline Pereira; Dusse, Luci Maria S; Fóscolo, Rodrigo Bastos; Reis, Janice Sepúlveda; Annichino-Bizzacchi, Joyce Maria; Orsi, Fernanda Loureiro de Andrade; Mazetto, Bruna de Moraes; Carvalho, Maria das Graças; Gomes, Karina Braga; Fernandes, Ana Paula

    2015-01-01

    We have investigated whether von Willebrand factor, ADAMTS13 (a disintegrin and metalloproteinase with thrombospondin type 1 motif, member 13), and D-Dimer were associated with different levels of renal function in patients with type 1 diabetes. Patients were classified according to level of renal function through estimated glomerular filtration rate: ≥90 and <130mL/min/1,73m2, n=52 (control group), ≥60 and <90mL/min/1,73m2, n=29 (mild renal dysfunction group), <60mL/min/1,73m2, n=28 (severe renal dysfunction group); and through urinary albumin excretion: normoalbuminuria, microalbuminuria and macroalbuminuria. Von Willebrand factor, ADAMTS13, and D-Dimer plasma levels were determined by enzyme-linked immunosorbent assay. ADAMTS13 activity was determined by fluorescence resonance energy transfer assay. Von Willebrand factor levels were increased in patients with mild (P=0.001) and severe (P<0.001) renal dysfunction as compared to the control group. ADAMTS13 levels were also increased in mild (P=0.029) and severe (P=0.002) renal dysfunction groups in comparison to the control group, while ADAMTS13 activity was increased only in the severe renal dysfunction group as compared to the control group (P=0.006). No significant differences were observed among the groups regarding von Willebrand factor/ADAMTS13 ratio. ADAMTS13 activity/ADAMTS13 levels ratio was reduced in patients with mild (P=0.013) and severe (P=0.015) renal dysfunction as compared to the control group. D-Dimer levels were increased in patients with mild (P=0.006) and severe (P<0.001) renal dysfunction as compared to the control group; it was also higher in patients with severe renal dysfunction as compared to the mild renal dysfunction group (P=0.019). Similar results were found for albuminuria classification. Increased von Willebrand factor, ADAMTS13, and D-Dimer levels and decreased ADAMTS13 activity/ADAMTS13 levels ratio are associated with renal dysfunction in patients with type 1 diabetes

  20. Cell type-specific regulation of von Willebrand factor expression by the E4BP4 transcriptional repressor.

    PubMed

    Hough, Christine; Cuthbert, Carla D; Notley, Colleen; Brown, Christine; Hegadorn, Carol; Berber, Ergul; Lillicrap, David

    2005-02-15

    Mechanisms of tissue-restricted patterns of von Willebrand factor (VWF) expression involve activators and repressors that limit expression to endothelial cells and megakaryocytes. The relative transcriptional activity of the proximal VWF promoter was assessed in VWF-producing and -nonproducing cells, and promoter activity was highest in endothelial cells followed by megakaryocytes. Only basal VWF promoter activity was seen in nonendothelial cells. Here we identify a negative response element located at nucleotides (nts) +96/+105 and demonstrate, using chromatin immunoprecipitation (ChIP) analysis, that in vivo this sequence interacts with the E4BP4 transcriptional repressor. Differences in size and relative abundance of nuclear E4BP4 were observed. In HepG2 cells, low levels of larger forms of E4BP4 are present that directly interact with the negative response element. In VWF-expressing cells, high levels of smaller forms predominate with no evidence of direct DNA binding. However, in endothelial cells, mutation of the VWF E4BP4 binding motif not only restores but also further elevates VWF promoter activity, suggesting that E4BP4 may be part of a coordinated binding complex. These observations implicate this binding motif in repressing both activated and basal levels of VWF transcription by different cell type-specific mechanisms, and support the hypothesis that E4BP4 sequesters negative regulators of transcription, thereby enhancing activated gene expression.

  1. Role of RNA splicing in mediating lineage-specific expression of the von Willebrand factor gene in the endothelium.

    PubMed

    Yuan, Lei; Janes, Lauren; Beeler, David; Spokes, Katherine C; Smith, Joshua; Li, Dan; Jaminet, Shou-Ching; Oettgen, Peter; Aird, William C

    2013-05-23

    We previously demonstrated that the first intron of the human von Willebrand factor (vWF) is required for gene expression in the endothelium of transgenic mice. Based on this finding, we hypothesized that RNA splicing plays a role in mediating vWF expression in the vasculature. To address this question, we used transient transfection assays in human endothelial cells and megakaryocytes with intron-containing and intronless human vWF promoter-luciferase constructs. Next, we generated knockin mice in which LacZ was targeted to the endogenous mouse vWF locus in the absence or presence of the native first intron or heterologous introns from the human β-globin, mouse Down syndrome critical region 1, or hagfish coagulation factor X genes. In both the in vitro assays and the knockin mice, the loss of the first intron of vWF resulted in a significant reduction of reporter gene expression in endothelial cells but not megakaryocytes. This effect was rescued to varying degrees by the introduction of a heterologous intron. Intron-mediated enhancement of expression was mediated at a posttranscriptional level. Together, these findings implicate a role for intronic splicing in mediating lineage-specific expression of vWF in the endothelium.

  2. Nanomechanical Contribution of Collagen and von Willebrand Factor A in Marine Underwater Adhesion and Its Implication for Collagen Manipulation.

    PubMed

    Yoo, Hee Young; Huang, Jun; Li, Lin; Foo, Mathias; Zeng, Hongbo; Hwang, Dong Soo

    2016-03-14

    Recent works on mussel adhesion have identified a load bearing matrix protein (PTMP1) containing von Willebrand factor (vWF) with collagen binding capability that contributes to the mussel holdfast by manipulating mussel collagens. Using a surface forces apparatus, we investigate for the first time, the nanomechanical properties of vWF-collagen interaction using homologous proteins of mussel byssus, PTMP1 and preCollagens (preCols), as collagen. Mimicking conditions similar to mussel byssus secretion (pH < 5.0) and seawater condition (pH 8.0), PTMP1 and preCol interact weakly in the "positioning" phase based on vWF-collagen binding and strengthen in "locked" phase due to the combined effects of electrostatic attraction, metal binding, and mechanical shearing. The progressive enhancement of binding between PTMP1 with porcine collagen under the aforementioned conditions is also observed. The binding mechanisms of PTMP1-preCols provide insights into the molecular interaction of the mammalian collagen system and the development of an artificial extracellular matrix based on collagens.

  3. Type II PI4-kinases control Weibel-Palade body biogenesis and von Willebrand factor structure in human endothelial cells

    PubMed Central

    Lopes da Silva, Mafalda; O'Connor, Marie N.; Kriston-Vizi, Janos; White, Ian J.; Al-Shawi, Raya; Simons, J. Paul; Mössinger, Julia; Haucke, Volker

    2016-01-01

    ABSTRACT Weibel-Palade bodies (WPBs) are endothelial storage organelles that mediate the release of molecules involved in thrombosis, inflammation and angiogenesis, including the pro-thrombotic glycoprotein von Willebrand factor (VWF). Although many protein components required for WPB formation and function have been identified, the role of lipids is almost unknown. We examined two key phosphatidylinositol kinases that control phosphatidylinositol 4-phosphate levels at the trans-Golgi network, the site of WPB biogenesis. RNA interference of the type II phosphatidylinositol 4-kinases PI4KIIα and PI4KIIβ in primary human endothelial cells leads to formation of an increased proportion of short WPB with perturbed packing of VWF, as exemplified by increased exposure of antibody-binding sites. When stimulated with histamine, these cells release normal levels of VWF yet, under flow, form very few platelet-catching VWF strings. In PI4KIIα-deficient mice, immuno-microscopy revealed that VWF packaging is also perturbed and these mice exhibit increased blood loss after tail cut compared to controls. This is the first demonstration that lipid kinases can control the biosynthesis of VWF and the formation of WPBs that are capable of full haemostatic function. PMID:27068535

  4. Weibel-Palade body size modulates the adhesive activity of its von Willebrand Factor cargo in cultured endothelial cells

    PubMed Central

    Ferraro, Francesco; Mafalda Lopes da, Silva; Grimes, William; Lee, Hwee Kuan; Ketteler, Robin; Kriston-Vizi, Janos; Cutler, Daniel F.

    2016-01-01

    Changes in the size of cellular organelles are often linked to modifications in their function. Endothelial cells store von Willebrand Factor (vWF), a glycoprotein essential to haemostasis in Weibel-Palade bodies (WPBs), cigar-shaped secretory granules that are generated in a wide range of sizes. We recently showed that forcing changes in the size of WPBs modifies the activity of this cargo. We now find that endothelial cells treated with statins produce shorter WPBs and that the vWF they release at exocytosis displays a reduced capability to recruit platelets to the endothelial cell surface. Investigating other functional consequences of size changes of WPBs, we also report that the endothelial surface-associated vWF formed at exocytosis recruits soluble plasma vWF and that this process is reduced by treatments that shorten WPBs, statins included. These results indicate that the post-exocytic adhesive activity of vWF towards platelets and plasma vWF at the endothelial surface reflects the size of their storage organelle. Our findings therefore show that changes in WPB size, by influencing the adhesive activity of its vWF cargo, may represent a novel mode of regulation of platelet aggregation at the vascular wall. PMID:27576551

  5. Expression of von Willebrand factor, pulmonary intravascular macrophages, and Toll-like receptors in lungs of septic foals

    PubMed Central

    Harrison, Jacqueline M. E.; Quanstrom, Leah M.; Robinson, Alex R.; Wobeser, Bruce; Anderson, Stacy L.

    2017-01-01

    Sepsis causes significant mortality in neonatal foals; however, there is little data describing the cellular and molecular pathways of lung inflammation in septic foals. This study was conducted to characterize lung inflammation in septic foals. Lung tissue sections from control (n = 6) and septic (n = 17) foals were compared using histology and immunohistology. Blinded pathologic scoring of hematoxylin and eosin stained samples revealed increased features of lung inflammation such as thickened alveolar septa and sequestered inflammatory cells in septic foals. Septic foal lungs showed increased expression of von Willebrand factor in blood vessels, demonstrating vascular inflammation. Use of MAC387 antibody to detect calprotectin as a reflection of mononuclear cell infiltration revealed a significant increase in their numbers in alveolar septa of lungs from septic foals compared to those from control foals. The mononuclear cells appeared to be mature macrophages and were located in the septal capillaries, suggesting they were pulmonary intravascular macrophages (PIMs). Finally, lungs from septic foals showed increased expression of Toll-like receptor 4 and 9 in mononuclear cells relative to the control. Taken together, this study is the first to show the expression of inflammatory molecules and an increase in PIMs in lungs from foals that died from sepsis. PMID:27297419

  6. Does von Willebrand factor improve the predictive ability of current risk stratification scores in patients with atrial fibrillation?

    PubMed Central

    García-Fernández, Amaya; Roldán, Vanessa; Rivera-Caravaca, José Miguel; Hernández-Romero, Diana; Valdés, Mariano; Vicente, Vicente; Lip, Gregory Y. H.; Marín, Francisco

    2017-01-01

    Von Willebrand factor (vWF) is a biomarker of endothelial dysfunction. We investigated its role on prognosis in anticoagulated atrial fibrillation (AF) patients and determined whether its addition to clinical risk stratification schemes improved event-risk prediction. Consecutive outpatients with non-valvular AF were recruited and rates of thrombotic/cardiovascular events, major bleeding and mortality were recorded. The effect of vWF on prognosis was calculated using a Cox regression model. Improvements in predictive accuracy over current scores were determined by calculating the integrated discrimination improvement (IDI), net reclassification improvement (NRI), comparison of receiver-operator characteristic (ROC) curves and Decision Curve Analysis (DCA). 1215 patients (49% males, age 76 (71–81) years) were included. Follow-up was almost 7 years. Significant associations were found between vWF and cardiovascular events, stroke, mortality and bleeding. Based on IDI and NRI, addition of vWF to CHA2DS2-VASc statistically improved its predictive value, but c-indexes were not significantly different. For major bleeding, the addition of vWF to HAS-BLED improved the c-index but not IDI or NRI. DCA showed minimal net benefit. vWF acts as a simple prognostic biomarker in AF and, whilst its addition to current scores statistically improves prediction for some endpoints, absolute changes and impact on clinical decision-making are marginal. PMID:28134282

  7. von Willebrand factor fibers promote cancer-associated platelet aggregation in malignant melanoma of mice and humans

    PubMed Central

    Bauer, Alexander T.; Suckau, Jan; Frank, Kathrin; Desch, Anna; Goertz, Lukas; Wagner, Andreas H.; Hecker, Markus; Goerge, Tobias; Umansky, Ludmila; Beckhove, Philipp; Utikal, Jochen; Gorzelanny, Christian; Diaz-Valdes, Nancy; Umansky, Viktor

    2015-01-01

    Tumor-mediated procoagulatory activity leads to venous thromboembolism and supports metastasis in cancer patients. A prerequisite for metastasis formation is the interaction of cancer cells with endothelial cells (ECs) followed by their extravasation. Although it is known that activation of ECs and the release of the procoagulatory protein von Willebrand factor (VWF) is essential for malignancy, the underlying mechanisms remain poorly understood. We hypothesized that VWF fibers in tumor vessels promote tumor-associated thromboembolism and metastasis. Using in vitro settings, mouse models, and human tumor samples, we showed that melanoma cells activate ECs followed by the luminal release of VWF fibers and platelet aggregation in tumor microvessels. Analysis of human blood samples and tumor tissue revealed that a promoted VWF release combined with a local inhibition of proteolytic activity and protein expression of ADAMTS13 (a disintegrin-like and metalloproteinase with thrombospondin type I repeats 13) accounts for this procoagulatory milieu. Blocking endothelial cell activation by the low-molecular-weight heparin tinzaparin was accompanied by a lack of VWF networks and inhibited tumor progression in a transgenic mouse model. Our findings implicate a mechanism wherein tumor-derived vascular endothelial growth factor-A (VEGF-A) promotes tumor progression and angiogenesis. Thus, targeting EC activation envisions new therapeutic strategies attenuating tumor-related angiogenesis and coagulation. PMID:25977583

  8. [Applying uncertainty theory in caring for the family of a von Willebrand disease patient experiencing first time upper gastrointestinal bleeding].

    PubMed

    Chung, Ai-Lun; Shun, Shiow-Ching; Lin, Chih-Yu

    2009-10-01

    The purpose of this report was to describe the nursing experience in helping a primary caregiver cope with uncertainty as his mother experienced upper gastrointestinal (UGI) bleeding underlying von Willebrand disease and Scleromyxedema in an Emergency Department between 10 and 18 July 2008. Mishel's Uncertainty Theory was applied to assess the caregiver's uncertainty and patient disease progression. Data were collected through clinical observation, chart review, and interviews. The caregiver's nursing problems were identified as (1) uncertainty caused by symptoms of the rare disease and the probability of recurrent bleeding in the future; (2) uncertainty caused by lack of knowledge about the disease; (3) uncertainty caused by lack of confidence in home caring issues after UGI bleeding. During the nursing period, we provided clinical information related to the disease and offered psychological support to the caregiver based on our Mishel's Uncertainty Scale assessment. Successful strategies utilized by our intervention helped the caregiver reduce level of uncertainty, increase confidence to care for his mother, and improve the quality of further home care.

  9. The pharmacokinetics and pharmacodynamics of desmopressin: effect on plasma factor VIII:C and von Willebrand factor.

    PubMed

    Argenti, D; Jensen, B K; Heald, D

    1997-01-01

    The relationship between plasma concentrations of desmopressin and clotting factors Factor VIII:C (FVIII:C) and von Willebrand Factor (vWF) were explored after a single 15-minute intravenous infusion of desmopressin (0.3 microg/kg) to 28 healthy male subjects. Individual plasma desmopressin-vWF and desmopressin-FVIII:C concentration/response-time data were fitted to a pharmacodynamic sigmoid E ( max ) model linked to a two-compartment open pharmacokinetic model (Ke0 link). The model demonstrated that the onset rate of pharmacodynamic activity for FVIII:C and vWF was relatively rapid following intravenous administration. However, the offset rate of pharmacodynamic activity was rate-limited by the elimination rate of desmopressin. Mean maximum pharmacodynamic activity for both factors was estimated to be three- to four-times higher than baseline activity, and the mean desmopressin concentrations that produce half-maximal effects were approximately 250 to 300 pg/mL. Interindividual variation in pharmacodynamic-parameter estimates were of the magnitude that suggests a wide range of pharmacodynamic responses are possible for a fixed desmopressin dose.

  10. The function of ultra-large von Willebrand factor multimers in high shear flow controlled by ADAMTS13.

    PubMed

    Reininger, A J

    2015-01-01

    The paradigm that platelet aggregation, which contributes to bleeding arrest and also to thrombovascular disorders, initiates after signaling-induced platelet activation has been refuted in past recent years. Platelets can form aggregates independently of activation when soluble von Willebrand factor (VWF) is present and the shear rate exceeds a certain threshold where active A1 domains become exposed in soluble VWF multimers and can bind to platelet glycoprotein Ib. Subsequently - fostering each other - VWF can self-assemble into large nets combining with platelets into large conglomerates, which are entirely reversible when they enter a flow region with shear rates below the threshold. In addition the threshold changes from approximately 20 000 s⁻¹ in wall parallel flow to approximately 10 000 s⁻¹ in stagnation point flow. VWF containing ultra-large multimers - as when just released from endothelial storage sites - has been shown to have the highest binding potential to platelets and to each other, thus facilitating rapid platelet accrual to sites of vessel injury and exposed subendothelial structures, i.e. collagen. The VWF nets as well as the platelet-VWF conglomerates are controlled by the cleaving protease ADAMTS13 within minutes under high shear flow. Therewith the hemostatic potential is delivered where needed and the thrombogenic potential is highly controlled twofold: by flow and enzymatic proteolytic cleavage.

  11. Type II PI4-kinases control Weibel-Palade body biogenesis and von Willebrand factor structure in human endothelial cells.

    PubMed

    Lopes da Silva, Mafalda; O'Connor, Marie N; Kriston-Vizi, Janos; White, Ian J; Al-Shawi, Raya; Simons, J Paul; Mössinger, Julia; Haucke, Volker; Cutler, Daniel F

    2016-05-15

    Weibel-Palade bodies (WPBs) are endothelial storage organelles that mediate the release of molecules involved in thrombosis, inflammation and angiogenesis, including the pro-thrombotic glycoprotein von Willebrand factor (VWF). Although many protein components required for WPB formation and function have been identified, the role of lipids is almost unknown. We examined two key phosphatidylinositol kinases that control phosphatidylinositol 4-phosphate levels at the trans-Golgi network, the site of WPB biogenesis. RNA interference of the type II phosphatidylinositol 4-kinases PI4KIIα and PI4KIIβ in primary human endothelial cells leads to formation of an increased proportion of short WPB with perturbed packing of VWF, as exemplified by increased exposure of antibody-binding sites. When stimulated with histamine, these cells release normal levels of VWF yet, under flow, form very few platelet-catching VWF strings. In PI4KIIα-deficient mice, immuno-microscopy revealed that VWF packaging is also perturbed and these mice exhibit increased blood loss after tail cut compared to controls. This is the first demonstration that lipid kinases can control the biosynthesis of VWF and the formation of WPBs that are capable of full haemostatic function.

  12. Weibel-Palade body size modulates the adhesive activity of its von Willebrand Factor cargo in cultured endothelial cells.

    PubMed

    Ferraro, Francesco; Mafalda Lopes da, Silva; Grimes, William; Lee, Hwee Kuan; Ketteler, Robin; Kriston-Vizi, Janos; Cutler, Daniel F

    2016-08-31

    Changes in the size of cellular organelles are often linked to modifications in their function. Endothelial cells store von Willebrand Factor (vWF), a glycoprotein essential to haemostasis in Weibel-Palade bodies (WPBs), cigar-shaped secretory granules that are generated in a wide range of sizes. We recently showed that forcing changes in the size of WPBs modifies the activity of this cargo. We now find that endothelial cells treated with statins produce shorter WPBs and that the vWF they release at exocytosis displays a reduced capability to recruit platelets to the endothelial cell surface. Investigating other functional consequences of size changes of WPBs, we also report that the endothelial surface-associated vWF formed at exocytosis recruits soluble plasma vWF and that this process is reduced by treatments that shorten WPBs, statins included. These results indicate that the post-exocytic adhesive activity of vWF towards platelets and plasma vWF at the endothelial surface reflects the size of their storage organelle. Our findings therefore show that changes in WPB size, by influencing the adhesive activity of its vWF cargo, may represent a novel mode of regulation of platelet aggregation at the vascular wall.

  13. New developments in lung endothelial heterogeneity: Von Willebrand factor, P-selectin, and the Weibel-Palade body.

    PubMed

    Ochoa, Cristhiaan D; Wu, Songwei; Stevens, Troy

    2010-04-01

    Quiescent pulmonary endothelium establishes an antithrombotic, anti-inflammatory surface that promotes blood flow. However, the endothelium rapidly responds to injury and inflammation by promoting thrombosis and enabling the directed transmigration of inflammatory cells, such as neutrophils, into the alveolar airspace. Although the endothelial cell signals responsible for establishing a prothrombotic surface are distinct from those responsible for recognizing circulating neutrophils, these processes are highly interrelated. Von Willebrand factor (VWF)-stimulated secretion plays an important role in thrombus formation, and P-selectin surface expression plays a key role in neutrophil binding necessary for transmigration. Both VWF and P-selectin are located within Weibel-Palade bodies in pulmonary arteries and arterioles, yet Weibel-Palade bodies are absent in capillaries. Despite the absence of the Weibel-Palade bodies, pulmonary capillaries express both VWF and P-selectin. The physiological and pathophysiological significance of these observations is unclear. In this review, we address some anatomical and physiological features that distinguish pulmonary artery, capillary, and vein endothelium. In addition, we review our current understanding regarding the stimulated secretion of VWF and P-selectin in pulmonary artery and capillary endothelium. This information is considered in the context of vasculitis and pneumonia, two pathophysiological processes to which the stimulated secretion of VWF and P-selectin contribute.

  14. Factor VIII alters tubular organization and functional properties of von Willebrand factor stored in Weibel-Palade bodies.

    PubMed

    Bouwens, Eveline A M; Mourik, Marjon J; van den Biggelaar, Maartje; Eikenboom, Jeroen C J; Voorberg, Jan; Valentijn, Karine M; Mertens, Koen

    2011-11-24

    In endothelial cells, von Willebrand factor (VWF) multimers are packaged into tubules that direct biogenesis of elongated Weibel-Palade bodies (WPBs). WPB release results in unfurling of VWF tubules and assembly into strings that serve to recruit platelets. By confocal microscopy, we have previously observed a rounded morphology of WPBs in blood outgrowth endothelial cells transduced to express factor VIII (FVIII). Using correlative light-electron microscopy and tomography, we now demonstrate that FVIII-containing WPBs have disorganized, short VWF tubules. Whereas normal FVIII and FVIII Y1680F interfered with formation of ultra-large VWF multimers, release of the WPBs resulted in VWF strings of equal length as those from nontransduced blood outgrowth endothelial cells. After release, both WPB-derived FVIII and FVIII Y1680F remained bound to VWF strings, which however had largely lost their ability to recruit platelets. Strings from nontransduced cells, however, were capable of simultaneously recruiting exogenous FVIII and platelets. These findings suggest that the interaction of FVIII with VWF during WPB formation is independent of Y1680, is maintained after WPB release in FVIII-covered VWF strings, and impairs recruitment of platelets. Apparently, intra-cellular and extracellular assembly of FVIII-VWF complex involves distinct mechanisms, which differ with regard to their implications for platelet binding to released VWF strings.

  15. Polydom: a secreted protein with pentraxin, complement control protein, epidermal growth factor and von Willebrand factor A domains.

    PubMed Central

    Gilgès, D; Vinit, M A; Callebaut, I; Coulombel, L; Cacheux, V; Romeo, P H; Vigon, I

    2000-01-01

    To identify extracellular proteins with epidermal growth factor (EGF) domains that are potentially involved in the control of haemopoiesis, we performed degenerate reverse-transcriptase-mediated PCR on the murine bone-marrow stromal cell line MS-5 and isolated a new partial cDNA encoding EGF-like domains related to those in the Notch proteins. Cloning and sequencing of the full-length cDNA showed that it encoded a new extracellular multi-domain protein that we named polydom. This 387 kDa mosaic protein contained a signal peptide followed by a new association of eight different protein domains, including a pentraxin domain and a von Willebrand factor type A domain, ten EGF domains, and 34 complement control protein modules. The human polydom mRNA is strongly expressed in placenta, its expression in the other tissues being weak or undetectable. The particular multidomain structure of the encoded protein suggests an important biological role in cellular adhesion and/or in the immune system. PMID:11062057

  16. Hypercortisolism and pregnancy upregulate von Willebrand factor through different mechanisms: report on a pregnant patient with Cushing's syndrome.

    PubMed

    Casonato, Alessandra; Daidone, Viviana; Pontara, Elena; Albiger, Nora; Cattini, Maria G; Scaroni, Carla

    2010-07-01

    Von Willebrand factor (VWF) is reportedly increased in pregnancy and Cushing's syndrome, inducing a hypercoagulable state. In Cushing's syndrome, VWF gene promoter polymorphisms modulate cortisol-dependent VWF upregulation, haplotype 1 (GCAG) and short GT-repeats (GT)(S) being the susceptible, and haplotype 2 (CTGA) and long GT-repeats (GT)(L) the protective pattern. We report on a Cushing's syndrome patient who became pregnant under hypercortisolism, in whom we monitored the evolution of her hypercoagulable state. During the active phase of Cushing's syndrome, the patient's VWF and factor VIII concentrations were normal, despite high urinary-free cortisol levels consistent with the presence of haplotype 2 and (GT)(L) alleles in the VWF gene promoter. VWF and factor VIII increased significantly and progressively after she became pregnant and peaked just before delivery, returning to normal 5 months later, while her hypercortisolism persisted. Our data indicate that two different mechanisms upregulate VWF under hypercortisolism and pregnancy, the latter being independent of the VWF promoter haplotypes sensitive to cortisol excess.

  17. Von Willebrand Factor Regulation in Patients with Acute and Chronic Cerebrovascular Disease: A Pilot, Case–Control Study

    PubMed Central

    Kraft, Peter; Drechsler, Christiane; Gunreben, Ignaz; Nieswandt, Bernhard; Stoll, Guido; Heuschmann, Peter Ulrich; Kleinschnitz, Christoph

    2014-01-01

    Background and Purpose In animal models, von Willebrand factor (VWF) is involved in thrombus formation and propagation of ischemic stroke. However, the pathophysiological relevance of this molecule in humans, and its potential use as a biomarker for the risk and severity of ischemic stroke remains unclear. This study had two aims: to identify predictors of altered VWF levels and to examine whether VWF levels differ between acute cerebrovascular events and chronic cerebrovascular disease (CCD). Methods A case–control study was undertaken between 2010 and 2013 at our University clinic. In total, 116 patients with acute ischemic stroke (AIS) or transitory ischemic attack (TIA), 117 patients with CCD, and 104 healthy volunteers (HV) were included. Blood was taken at days 0, 1, and 3 in patients with AIS or TIA, and once in CCD patients and HV. VWF serum levels were measured and correlated with demographic and clinical parameters by multivariate linear regression and ANOVA. Results Patients with CCD (158±46%) had significantly higher VWF levels than HV (113±36%, P<0.001), but lower levels than AIS/TIA patients (200±95%, P<0.001). Age, sex, and stroke severity influenced VWF levels (P<0.05). Conclusions VWF levels differed across disease subtypes and patient characteristics. Our study confirms increased VWF levels as a risk factor for cerebrovascular disease and, moreover, suggests that it may represent a potential biomarker for stroke severity, warranting further investigation. PMID:24937073

  18. Von Willebrand factor and coagulation factor VIII in Moyamoya disease associated with Graves' disease: A case report

    PubMed Central

    Ren, Shou-Chen; Gao, Bao-Qin; Yang, Wei-Li; Feng, Wei-Xin; Xu, Jian; Li, Shao-Wu; Wang, Yong-Jun

    2016-01-01

    The present study reported the case of a Chinese boy who was diagnosed with Moyamoya disease (MMD) associated with Graves' disease (GD). An overactivation of von Willebrand factor (vWF) and coagulation factor VIII (FVIII) was identified in the plasma of the patient. Thiamazole and metoprolol treatment was thus administrated. After 2 months of treatment, the patient's thyroid function returned to normal and the neurological symptoms improved gradually. At the same time, the activities of vWF and FVIII were depressed. During the 20-month follow-up, information regarding the neurological symptoms, cerebrovascular imaging, thyroid function, thyroid autoantibodies and coagulation parameters was collected. High levels of thyroid autoantibodies persisted throughout the follow-up period, while other coagulation parameters remained in the normal range. In conclusion, considering the vital role of vWF and FVIII in vascular diseases, it is hypothesized that these two factors may serve an important role in the occurrence of GD associated with MMD. PMID:27882137

  19. Analysis of von Willebrand factor A domain-related protein (WARP) polymorphism in temperate and tropical Plasmodium vivax field isolates

    PubMed Central

    Gholizadeh, Saber; Djadid, Navid Dinparast; Basseri, Hamid Reza; Zakeri, Sedigheh; Ladoni, Hossein

    2009-01-01

    Background The identification of key molecules is crucial for designing transmission-blocking vaccines (TBVs), among those ookinete micronemal proteins are candidate as a general class of malaria transmission-blocking targets. Here, the sequence analysis of an extra-cellular malaria protein expressed in ookinetes, named von Willebrand factor A domain-related protein (WARP), is reported in 91 Plasmodium vivax isolates circulating in different regions of Iran. Methods Clinical isolates were collected from north temperate and southern tropical regions in Iran. Primers have been designed based on P. vivax sequence (ctg_6991) which amplified a fragment of about 1044 bp with no size variation. Direct sequencing of PCR products was used to determine polymorphism and further bioinformatics analysis in P. vivax sexual stage antigen, pvwarp. Results Amplified pvwarp gene showed 886 bp in size, with no intron. BLAST analysis showed a similarity of 98–100% to P. vivax Sal-I strain; however, Iranian isolates had 2 bp mismatches in 247 and 531 positions that were non-synonymous substitution [T (ACT) to A (GCT) and R (AGA) to S (AGT)] in comparison with the Sal-I sequence. Conclusion This study presents the first large-scale survey on pvwarp polymorphism in the world, which provides baseline data for developing WARP-based TBV against both temperate and tropical P. vivax isolates. PMID:19549316

  20. Neutrophil Protease Cleavage of Von Willebrand Factor in Glomeruli - An Anti-thrombotic Mechanism in the Kidney.

    PubMed

    Tati, Ramesh; Kristoffersson, Ann-Charlotte; Manea Hedström, Minola; Mörgelin, Matthias; Wieslander, Jörgen; van Kooten, Cees; Karpman, Diana

    2017-02-01

    Adequate cleavage of von Willebrand factor (VWF) prevents formation of thrombi. ADAMTS13 is the main VWF-cleaving protease and its deficiency results in development of thrombotic microangiopathy. Besides ADAMTS13 other proteases may also possess VWF-cleaving activity, but their physiological importance in preventing thrombus formation is unknown. This study investigated if, and which, proteases could cleave VWF in the glomerulus. The content of the glomerular basement membrane (GBM) was studied as a reflection of processes occurring in the subendothelial glomerular space. VWF was incubated with human GBMs and VWF cleavage was assessed by multimer structure analysis, immunoblotting and mass spectrometry. VWF was cleaved into the smallest multimers by the GBM, which contained ADAMTS13 as well as neutrophil proteases, elastase, proteinase 3 (PR3), cathepsin-G and matrix-metalloproteinase 9. The most potent components of the GBM capable of VWF cleavage were in the serine protease or metalloprotease category, but not ADAMTS13. Neutralization of neutrophil serine proteases inhibited GBM-mediated VWF-cleaving activity, demonstrating a marked contribution of elastase and/or PR3. VWF-platelet strings formed on the surface of primary glomerular endothelial cells, in a perfusion system, were cleaved by both elastase and the GBM, a process blocked by elastase inhibitor. Ultramorphological studies of the human kidney demonstrated neutrophils releasing elastase into the GBM. Neutrophil proteases may contribute to VWF cleavage within the subendothelium, adjacent to the GBM, and thus regulate thrombus size. This anti-thrombotic mechanism would protect the normal kidney during inflammation and could also explain why most patients with ADAMTS13 deficiency do not develop severe kidney failure.

  1. Degradation of circulating von Willebrand factor and its regulator ADAMTS13 implicates secreted Bacillus anthracis metalloproteases in anthrax consumptive coagulopathy.

    PubMed

    Chung, Myung-Chul; Popova, Taissia G; Jorgensen, Shelley C; Dong, Li; Chandhoke, Vikas; Bailey, Charles L; Popov, Serguei G

    2008-04-11

    Pathology data from the anthrax animal models show evidence of significant increases in vascular permeability coincident with hemostatic imbalances manifested by thrombocytopenia, transient leucopenia, and aggressive disseminated intravascular coagulation. In this study we hypothesized that anthrax infection modulates the activity of von Willebrand factor (VWF) and its endogenous regulator ADAMTS13, which play important roles in hemostasis and thrombosis, including interaction of endothelial cells with platelets. We previously demonstrated that purified anthrax neutral metalloproteases Npr599 and InhA are capable of cleaving a variety of host structural and regulatory proteins. Incubation of human plasma with these proteases at 37 degrees C in the presence of urea as a mild denaturant results in proteolysis of VWF. Also in these conditions, InhA directly cleaves plasma ADAMTS13 protein. Npr599 and InhA digest synthetic VWF substrate FRETS-VWF73. Amino acid sequencing of VWF fragments produced by InhA suggests that one of the cleavage sites of VWF is located at domain A2, the target domain of ADAMTS13. Proteolysis of VWF by InhA impairs its collagen binding activity (VWF:CBA) and ristocetin-induced platelet aggregation activity. In plasma from anthrax spore-challenged DBA/2 mice, VWF antigen levels increase up to 2-fold at day 3 post-infection with toxigenic Sterne 34F(2) strain, whereas VWF:CBA levels drop in a time-dependent manner, suggesting dysfunction of VWF instead of its quantitative deficiency. This conclusion is further supported by significant reduction in the amount of VWF circulating in blood in the ultra-large forms. In addition, Western blot analysis shows proteolytic depletion of ADAMTS13 from plasma of spore-challenged mice despite its increased expression in the liver. Our results suggest a new mechanism of anthrax coagulopathy affecting the levels and functional activities of both VWF and its natural regulator ADAMTS13. This mechanism may

  2. Effect of Vitamin D Status on Von Willebrand Factor and ADAMTS13 in Diabetic Patients on Chronic Hemodialysis

    PubMed Central

    Cohen-Hagai, Keren; Rashid, Gloria; Einbinder, Yael; Ohana, Meital; Benchetrit, Sydney

    2017-01-01

    Von Willebrand factor (vWF) is a glycoprotein with a crucial role in the formation of platelet thrombi, and ADAMTS13 is the main enzyme responsible for vWF cleavage. Both are important in the relationship between diabetic nephropathy, hypercoagulability, and cardiovascular disease. This study evaluated a potential relationship between vitamin D (vitD) levels, vWF, ADAMTS13 activity, and inflammation in diabetic patients on chronic hemodialysis (HD). Blood samples from 52 diabetic patients on chronic HD were obtained to determine vitD levels, vWF, and ADAMTS13 activity, and inflammatory markers. HD patients were grouped according to 25-hydroxyvitamin D [25(OH) VitD]<25 nmol/L (n=16) or >25 nmol/L (n=36). vWF antigen and vWF activity were elevated in both groups, with an average of 214.3±82.6% and 175.8±72.6%, respectively. Average ADAMTS13 activity was within the normal range in both groups. Blood samples from the vitD <25 nmol/L group showed a positive correlation between c-reactive protein (CRP) and vWF levels (P=0.023; r=0.564; 95% confidence interval=0.095-0.828), with a negative correlation between HbA1c and 25(OH) VitD (P=0.015; r=-0.337; 95% confidence interval=-0.337-0.19). Diabetic patients on chronic HD had elevated vWF levels and activity with no significant change in ADAMTS13 activity. The correlation between CRP and vWF levels in the 25(OH) VitD<25 nmol/L group suggests inflammatory-related endothelial dysfunction in these patients. PMID:28029003

  3. Molecular Imaging of Platelet-Endothelial Interactions and Endothelial Von Willebrand Factor In Early and Mid-Stage Atherosclerosis

    PubMed Central

    Shim, Chi Young; Liu, Ya Ni; Atkinson, Tamara; Xie, Aris; Foster, Ted; Davidson, Brian P.; Treible, Mackenzie; Qi, Yue; López, José A.; Munday, Adam; Ruggeri, Zaverio; Lindner, Jonathan R.

    2015-01-01

    Background Non-thrombotic platelet-endothelial interactions may contribute to atherosclerotic plaque development, although in vivo studies examining mechanism without platelet pre-activation are lacking. Using in vivo molecular imaging at various stages of atherosclerosis, we quantified platelet-endothelial interactions and evaluated the contribution of major adhesion pathways. Methods and Results Mice deficient for the LDL-receptor and Apobec-1 were studied as an age-dependent model of atherosclerosis at 10, 20, 30, and 40 wks of age, which provided progressive increase in stage from very early fatty streak (10 wks) to large complex plaques without rupture (40 wks). Platelet-targeted contrast ultrasound molecular imaging of the thoracic aorta performed with microbubbles targeted to GPIbα demonstrated selective signal enhancement as early as 10 weeks of age. This signal increased progressively with age (almost 8-fold increase from 10 to 40 weeks, ANOVA p<0.001). Specificity for platelet targeting was confirmed by the reduction in platelet-targeted signal commensurate with the decrease in platelet count after immunodepletion with anti-GPIb or anti-CD41 antibody. Inhibition of P-selectin in 20 and 40 wk atherosclerotic mice resulted in a small (15-30%) reduction in platelet signal. Molecular imaging with microbubbles targeted to the A1 domain of von Willebrand factor (VWF) demonstrated selective signal enhancement at all time points which did not significantly increase with age. Treatment of 20 and 40 week mice with recombinant ADAMTS13 eliminated platelet and VWF molecular imaging signal. Conclusions Platelet-endothelial interactions occur in early atherosclerosis. These interactions are in part due to endothelial VWF large multimers which can be reversed with exogenous ADAMTS13. PMID:26156014

  4. ABO blood group antigens on human plasma von Willebrand factor after ABO-mismatched bone marrow transplantation.

    PubMed

    Matsui, T; Shimoyama, T; Matsumoto, M; Fujimura, Y; Takemoto, Y; Sako, M; Hamako, J; Titani, K

    1999-10-15

    von Willebrand factor (vWF) is synthesized exclusively by endothelial cells and megakaryocytes, and stored in the intracellular granules or constitutively secreted into plasma. ABO blood group antigens are covalently associated with asparagine-linked sugar chains of plasma vWF. The effect of ABO-mismatched bone marrow transplantation (BMT) or blood stem cell transplantation (BSCT) on the expression of ABO blood group antigens on the vWF was examined to obtain information on the origin of these antigens. In ABO-mismatched (HLA-matched) groups, 8 cases of BMT and 4 cases of BSCT were examined. In all cases, the ABO blood groups on red blood cells were gradually converted to the donor's type within 80 to 90 days after the transplantation. The blood group antigens on the vWF were consistent with the recipient's blood group for the period monitored by enzyme-linked immunosorbent assay (ELISA). When vWF was isolated from normal platelets and examined for the blood group antigens using ELISA or immunoblotting, it showed few antigens. However, vWF extracted from veins expressed blood group antigens. These findings indicate that platelet (megakaryocyte)-derived vWF does not contain blood group antigens and that these antigens may be specifically associated with vWF synthesized in endothelial cells and secreted into plasma. Furthermore, it is possible that the persistence of the recipient's blood group antigens on plasma glycoproteins such as vWF, independent of the donor-derived erythrocytes, after ABO-mismatched stem cell transplantation, may influence the immunological system in the production of anti-blood group antibodies resulting in the establishment of immunological tolerance in the recipient plasma.

  5. Purification of human von Willebrand factor-cleaving protease and its identification as a new member of the metalloproteinase family.

    PubMed

    Fujikawa, K; Suzuki, H; McMullen, B; Chung, D

    2001-09-15

    von Willebrand factor (vWF) is synthesized in megakaryocytes and endothelial cells as a very large multimer, but circulates in plasma as a group of multimers ranging from 500 to 10 000 kd. An important mechanism for depolymerization of the large multimers is the limited proteolysis by a vWF-cleaving protease present in plasma. The absence or inactivation of the vWF-cleaving protease results in the accumulation of large multimers, which may cause thrombotic thrombocytopenic purpura. The vWF-cleaving protease was first described as a Ca(++)-dependent proteinase with an apparent molecular weight of approximately 300 kd. Thus far, however, it has not been isolated and characterized. In this study, the purification of human vWF-cleaving protease from a commercial preparation of factor VIII/vWF concentrate by means of several column chromatographic steps, including 2 steps of heparin-Sepharose column, is reported. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of the anion exchange and gel filtration column fractions showed that the vWF-cleaving protease activity corresponded to a protein band of 150 kd. After reduction, it migrated with an apparent weight of 190 kd. The amino terminal sequence of the 150-kd band was AAGGIL(H)LE(L)L(D)AXG(P)X(V)XQ (single-letter amino acid codes), with the tentative residues shown in parentheses. A search of the human genome sequence identified the vWF-cleaving protease as a new member of the ADAMTS (a disintegrin and metalloproteinase with thrombospondin type I motif) family of metalloproteinase. An active site sequence of HEIGHSFGLEHE (single-letter amino acid codes) was located at 150 residues from the N terminus of the protein.

  6. Cyclic adenosine monophosphate-dependent mechanisms induce von Willebrand factor expression in the Dami megakaryoblastic cell line.

    PubMed

    Deguine, V; Kerbiriou-Nabias, D; Lecoq, D; Greenberg, S M; Meyer, D; Dosne, A M

    1995-02-01

    It has been proposed that cyclic adenosine monophosphate (cAMP) is involved in the differentiation of several cell types and this study analysed whether von Willebrand factor (vWf) synthesis, which is a marker of the megakaryocyte maturation of these cells, would be enhanced by agents acting on cAMP formation. Different compounds known to stimulate cAMP accumulation in cells were used: dibutyryl cAMP (db-cAMP), isobutyl-methylxanthine (IBMX) or pentoxifylline (PTX) and forskolin. Treatments with db-cAMP or IBMX (10-1,000 microM) induced a dose-dependent increase in vWf synthesis. Associations of IBMX with forskolin produced a synergistic enhancement in vWf synthesis. PTX alone did not enhance vWf synthesis but a latent effect was revealed in the presence of forskolin or db-cAMP. The increase in vWf mRNA shown by Northern blot analysis demonstrates that the protein synthesis correlates with the transcript expression after db-cAMP or IBMX treatments. vWf synthesis paralleled the accumulation of cAMP in the cells. Moreover vWf expression induced by combination of IBMX with forskolin was associated with a moderate increase in the percentage of GPIIb/IIIa positive cells and in the ploidy level related to an important inhibition of cell growth. These data provide evidence that agents acting on cAMP metabolism induce vWf synthesis in the Dami megakaryoblastic cells.

  7. Predictive value of von Willebrand factor for adverse clinical outcome in hypertensive patients with mild-to-moderate aortic regurgitation.

    PubMed

    Iida, M; Nihei, M; Yamazaki, M; Sawaguchi, M; Honjo, H; Kodama, I; Kamiya, K

    2008-04-01

    Plasma levels of von Willebrand factor (vWF), a marker of endothelial dysfunction/damage, are elevated in high-risk hypertensive patients and in patients with severe aortic regurgitation (AR). Patients with mild-to-moderate AR, frequently detected in hypertensive elderly, have additional left ventricular morphological and functional dysfunctions. We hypothesized that hypertensive patients with mild-to-moderate AR may have enhanced endothelial and/or left ventricular dysfunctions that may lead to a deteriorated prognosis. We measured vWF, prothrombin F1+2 (F 1+2) as a marker of thrombin generation, brain natriuretic peptide (BNP) in 104 hypertensive patients with mild-to-moderate AR and 66 hypertensive patients without AR. The left ventricular diameter at systole (LVDs) and left ventricular posterior wall thickness (LVWT) were determined by echocardiography and indexed by body surface area (LVDs/BSA and LVWT/BSA). VWF (median, interquartile range (IQR) 154, 120-196%) and BNP (34.7 pg ml(-1), 15-65%) levels were greater in patients with AR than in those without AR (135, 98-175% and 20, 10.3-49 pg ml(-1)). All patients were prospectively followed up for cardiac events during the period of median 43 months (IQR 31-81). Patients with AR had an increased risk of cardiac events (regression ratio (RR) 1.87, 95% confidence interval 1.28-2.87) when compared to those without AR. A multivariate Cox hazard analysis indicated that log vWF (RR 4.93) and log BNP (RR 1.9) were independent predictors in patients with AR. VWF was an independent predictor of clinical outcome in hypertensive patients with mild-to-moderate AR.

  8. Minimum wound size for clotting: flowing blood coagulates on a single collagen fiber presenting tissue factor and von Willebrand factor.

    PubMed

    Zhu, Shu; Tomaiuolo, Maurizio; Diamond, Scott L

    2016-08-08

    It is unknown if a lower size limit exists for human blood coagulation under flow over physiological vessel wall triggers as small as a single collagen fiber. Prior determinations of the smallest sized surface stimuli necessary for clotting of human blood, defined as the patch size threshold, have not deployed whole blood, hemodynamic flow, and platelet adhesive stimuli. For whole blood perfused in microfluidic devices, we report that steady venous flow (wall shear rate, 100 s(-1)) was sufficient to drive platelet deposition on 20 micron long zones of collagen fibers or on a single fiber. With tissue factor (TF)-coated collagen, flowing blood generated robust platelet deposits, platelet-localized thrombin, and fibrin on a single collagen fiber, thus demonstrating the absence of a physiological patch size threshold under venous flow. In contrast, at arterial wall shear rate (1000 s(-1)) with TF present, essentially no platelet or fibrin deposition occurred on 20 micron collagen zones or on a single collagen fiber, demonstrating a patch threshold, which was overcome by pre-coating the collagen with von Willebrand factor (vWF). For venous flows, human blood can clot on one of the smallest biological units of a single collagen fiber presenting TF. For arterial flows, vWF together with TF allows human blood to generate thrombin and fibrin on a patch stimulus as limited as a single collagen fiber. vWF-dependent platelet adhesion represents a particle-based sensing mechanism of micron-scale stimuli that then allows amplification of the molecular components of TF-driven thrombin and fibrin production under arterial flow.

  9. Primary postpartum haemorrhage in women with von Willebrand disease or carriership of haemophilia despite specialised care: a retrospective survey.

    PubMed

    Stoof, S C M; van Steenbergen, H W; Zwagemaker, A; Sanders, Y V; Cannegieter, S C; Duvekot, J J; Leebeek, F W G; Peters, M; Kruip, M J H A; Eikenboom, J

    2015-07-01

    Pregnant women with bleeding disorders require specialised peripartum care to prevent postpartum haemorrhage (PPH). If third trimester coagulation factor levels are <0.50 IU mL(-1) , prophylactic treatment is indicated and administered according to international guidelines. However, optimal dose and duration are unknown and bleeding may still occur. The aim of this study was to investigate the outcome in women with von Willebrand disease (VWD) or haemophilia carriership treated according to current practice guidelines. From the period 2002-2011, 185 deliveries in 154 VWD women or haemophilia carriers were retrospectively included. Data on blood loss, bleeding disorder characteristics and obstetric risk factors were obtained. The outcome was primary PPH, defined as blood loss ≥500 mL within 24 h postpartum and severe PPH as blood loss ≥1000 mL. Primary PPH was observed in 62 deliveries (34%), 14 (8%) of which resulted in severe PPH. In 26 deliveries prophylactic treatment was administered due to factor levels below the 0.50 IU mL(-1) cut-off in the third trimester, 14 of which (54%) were complicated by PPH. We found an increased PPH risk in deliveries given prophylactic treatment compared with deliveries without (OR 2.7, 95% CI 1.2-6.3). In conclusion, PPH incidence was highest in deliveries with the lowest factor levels in the third trimester. Currently, delivery outcome in women with bleeding disorders is unsatisfactory, given the high PPH incidence despite specialised care. Future studies are required to optimise management of deliveries in this patient population.

  10. A Model for the Conformational Activation of the Structurally Quiescent Metalloprotease ADAMTS13 by Von Willebrand Factor.

    PubMed

    South, Kieron; Freitas, Marta O; Lane, David A

    2017-02-16

    Blood loss is prevented by the multi-domain glycoprotein von Willebrand factor (VWF), which binds exposed collagen at damaged vessels and captures platelets. VWF is regulated by the metalloprotease ADAMTS13, which, in turn, is conformationally activated by VWF. To delineate the structural requirements for VWF-mediated conformational activation of ADAMTS13, we performed binding and functional studies with a panel of truncated ADAMTS13 variants. We demonstrate that both the isolated CUB1 and CUB2 domains in ADAMTS13 bind to the spacer domain exosite of a truncated ADAMTS13 variant, MDTCS (KD of 135 ± 10.1 nM and 86.9 ± 9.0 nM, respectively). However, only the CUB1 domain inhibited proteolytic activity of MDTCS. Moreover, ADAMTS13∆CUB2, unlike ADAMTS13∆CUB1-2, exhibited activity similar to wild-type ADAMTS13 and could be activated by VWF D4-CK. The CUB2 domain is therefore not essential for maintaining the inactive conformation of ADAMTS13. Both CUB domains could bind to the VWF D4-CK domain fragment (KD of 53.7± 2.1 nM and 84.3 ± 2.0 nM, respectively). However, deletion of both CUB domains did not prevent VWF D4-CK binding, suggesting that competition for CUB-domain binding to the spacer domain is not the dominant mechanism behind the conformational activation. ADAMTS13∆TSP8-CUB2 could no longer bind to VWF D4-CK, and deletion of TSP8 abrogated ADAMTS13 conformational activation. These findings support an ADAMTS13-activation model in which VWF D4-CK engages the TSP8-CUB2 domains, inducing the conformational change that disrupts the CUB1-spacer domain interaction and thereby activates ADAMTS13.

  11. Effect of Vitamin D Status on Von Willebrand Factor and ADAMTS13 in Diabetic Patients on Chronic Hemodialysis.

    PubMed

    Cohen-Hagai, Keren; Rashid, Gloria; Einbinder, Yael; Ohana, Meital; Benchetrit, Sydney; Zitman-Gal, Tali

    2017-03-01

    Von Willebrand factor (vWF) is a glycoprotein with a crucial role in the formation of platelet thrombi, and ADAMTS13 is the main enzyme responsible for vWF cleavage. Both are important in the relationship between diabetic nephropathy, hypercoagulability, and cardiovascular disease. This study evaluated a potential relationship between vitamin D (vitD) levels, vWF, ADAMTS13 activity, and inflammation in diabetic patients on chronic hemodialysis (HD). Blood samples from 52 diabetic patients on chronic HD were obtained to determine vitD levels, vWF, and ADAMTS13 activity, and inflammatory markers. HD patients were grouped according to 25-hydroxyvitamin D [25(OH) VitD]<25 nmol/L (n=16) or >25 nmol/L (n=36). vWF antigen and vWF activity were elevated in both groups, with an average of 214.3±82.6% and 175.8±72.6%, respectively. Average ADAMTS13 activity was within the normal range in both groups. Blood samples from the vitD <25 nmol/L group showed a positive correlation between c-reactive protein (CRP) and vWF levels (P=0.023; r=0.564; 95% confidence interval=0.095-0.828), with a negative correlation between HbA1c and 25(OH) VitD (P=0.015; r=-0.337; 95% confidence interval=-0.337-0.19). Diabetic patients on chronic HD had elevated vWF levels and activity with no significant change in ADAMTS13 activity. The correlation between CRP and vWF levels in the 25(OH) VitD<25 nmol/L group suggests inflammatory-related endothelial dysfunction in these patients.

  12. Von Willebrand factor and alkaline phosphatase predict re-transplantation-free survival after the first liver transplantation

    PubMed Central

    Wannhoff, Andreas; Rauber, Conrad; Friedrich, Kilian; Rupp, Christian; Stremmel, Wolfgang; Weiss, Karl Heinz; Schemmer, Peter

    2016-01-01

    Background After liver transplantation (LT), there are liver-related, infectious and cardiovascular complications that contribute to reduced graft survival. These conditions are associated with an increase in the Von Willebrand factor antigen (VWF-Ag), which was previously correlated with survival in cirrhotic patients. Objective Evaluate VWF-Ag as a predictive marker of re-transplantation-free survival in patients after LT. Methods We measured VWF-Ag in patients after first LT and then followed them prospectively with regard to the primary endpoint, namely re-transplantation-free survival. Results There were 6 out of 80 patients who died or received re-LT during follow-up. In these patients, the median VWF-Ag was 510.6%, which was significantly higher (p = 0.001) than in the patients who were alive at the end of follow-up (with a median VWF-Ag = 186.8%). At a cut-off of 286.8%, VWF-Ag was significantly correlated with re-transplantation-free survival (p < 0.001). VWF-Ag was independently associated with re-transplantation-free survival in a multivariate analysis; as was alkaline phosphatase (ALP), but not the model of end-stage liver disease (MELD) score, donor age, nor cold ischemia time. A score combining VWF-Ag and ALP showed an impressive capability in the receiver operating characteristic (ROC) analysis (with area under the curve (AUC) = 0.958) to distinguish between patients with regard to the primary endpoint. Conclusions VWF-Ag is a non-invasive marker that can predict outcome in patients after LT. Its diagnostic performance increased when combined with ALP in a newly developed scoring system.

  13. Trigramin: Primary structure and its inhibition of von Willebrand factor binding to glycoprotein IIb/IIIa complex on human platelets

    SciTech Connect

    Huang, Turfu; Holt, J.C.; Kirby, E.P.; Niewiarowski, S.

    1989-01-24

    Trigramin, a naturally occurring peptide purified from Trimeresurus gramineus snake venom, inhibits platelet aggregation and the binding of {sup 125}I-fibrinogen to ADP-stimulated platelets without affecting the platelet-release reaction. {sup 125}I-trigramin binds to ADP-stimulated and to chymotrypsin-treated normal platelets but not to thrombasthenic platelets. {sup 125}I-trigramin binding to platelets is blocked by monoclonal antibodies directed against the glycoprotein IIb/IIIa complex and by Arg-Gly-Asp-Ser (RGDS). The authors determined the primary structure of trigramin, which is composed of a single polypeptide chain of 72 amino acid residues and six disulfide bridges. The molecular weight of trigramin calculated on the basis of amino acid sequence was 7500, and the average pI was 5.61. An RGD sequence appeared in the carboxy-terminal domain of trigramin. An amino-terminal fragment (7-33) of trigramin showed 39% homology with a region (1555-1581) of von Willebrand factor (vWF). Trigramin also showed 36% identity in a 42 amino acid overlap and 53% identity in a 15 amino acid overlap when compared with two adhesive proteins, collagen {alpha}{sub 1} (I) and laminin B{sub 1}, respectively. Trigramin blocked binding of human vWF to the glycoprotein IIb/IIIa complex in thrombin-activated platelets in a dose-dependent manner. In conclusion, the data suggest that the biological activity of trigramin may depend upon the presence of an RGD sequence, the secondary structure of the molecule, and perhaps some other sequences that it shares with adhesive proteins.

  14. Plasma ADAMTS13, von Willebrand Factor (VWF), and VWF Propeptide Profiles in Patients With Connective Tissue Diseases and Antiphospholipid Syndrome.

    PubMed

    Habe, Koji; Wada, Hideo; Matsumoto, Takeshi; Ohishi, Kohshi; Ikejiri, Makoto; Tsuda, Kenshiro; Kondo, Makoto; Kamimoto, Yuki; Ikeda, Tomoaki; Katayama, Naoyuki; Mizutani, Hitoshi

    2016-01-11

    Thrombotic thrombocytopenic purpura (TTP) frequently develops in patients with connective tissue diseases (CTDs). ADAMTS13 and von Willebrand factor (VWF) are closely related to the onset of TTP. We investigated the roles of ADAMTS13 and VWF in thrombotic events of patients with CTD. ADAMTS13 activity and VWF and VWF propeptide (VWFpp) levels in CTD, primary antiphospholipid antibody syndrome (pAPS), and controls were measured to examine their relationship with thrombosis. ADAMTS13 activity levels were significantly low in the patients with CTD but not in the patients with pAPS. No significant difference in the ADAMTS13 activity levels among the various CTD subgroups was found. The levels of VWF and VWFpp were significantly elevated in the patients with pAPS and CTD compared with that of control groups. Eleven patients with CTD developed TTP, and their ADAMTS13 activity levels were significantly lower than patients having CTD without TTP. However, the ADAMTS13 activity levels showed no difference between the patients having CTD with and without thrombotic events. The VWF antigen levels were significantly high in the patients having CTD with TTP. There were no significant differences in the VWF levels of the patients having CTD with TTP and thrombosis. The VWFpp levels were significantly high in the patients having CTD with TTP and thrombosis. The VWF and VWFpp levels were significantly high in the patients with pAPS. Decreased ADAMTS13 activity and elevated VWF and VWFpp levels were observed in patients with CTD. These abnormalities in patients with CTD may represent the increased risk of thrombosis in CTD.

  15. Gene silencing of endothelial von Willebrand Factor attenuates angiotensin II-induced endothelin-1 expression in porcine aortic endothelial cells

    PubMed Central

    Dushpanova, Anar; Agostini, Silvia; Ciofini, Enrica; Cabiati, Manuela; Casieri, Valentina; Matteucci, Marco; Del Ry, Silvia; Clerico, Aldo; Berti, Sergio; Lionetti, Vincenzo

    2016-01-01

    Expression of endothelin (ET)-1 is increased in endothelial cells exposed to angiotensin II (Ang II), leading to endothelial dysfunction and cardiovascular disorders. Since von Willebrand Factor (vWF) blockade improves endothelial function in coronary patients, we hypothesized that targeting endothelial vWF with short interference RNA (siRNA) prevents Ang II-induced ET-1 upregulation. Nearly 65 ± 2% silencing of vWF in porcine aortic endothelial cells (PAOECs) was achieved with vWF-specific siRNA without affecting cell viability and growth. While showing ET-1 similar to wild type cells at rest, vWF-silenced cells did not present ET-1 upregulation during exposure to Ang II (100 nM/24 h), preserving levels of endothelial nitric oxide synthase activity similar to wild type. vWF silencing prevented AngII-induced increase in nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX) activity and superoxide anion (O2−) levels, known triggers of ET-1 expression. Moreover, no increase in O2− or ET-1 levels was found in silenced cells treated with AngII or NOX-agonist phorbol ester (PMA 5 nM/48 h). Finally, vWF was required for overexpression of NOX4 and NOX2 in response to AngII and PMA. In conclusion, endothelial vWF knockdown prevented Ang II-induced ET-1 upregulation through attenuation of NOX-mediated O2− production. Our findings reveal a new role of vWF in preventing of Ang II-induced endothelial dysfunction. PMID:27443965

  16. Immunohistochemical expression of endothelial markers CD31, CD34, von Willebrand factor, and Fli-1 in normal human tissues.

    PubMed

    Pusztaszeri, Marc P; Seelentag, Walter; Bosman, Fred T

    2006-04-01

    Few systematic studies have been published comparing the expression and distribution of endothelial cell (EC) markers in different vascular beds in normal human tissues. We investigated by immunohistochemistry the expression of CD31, CD34, von Willebrand factor (vWF), and Fli-1 in EC of the major organs and large vessels. Tissue samples obtained from autopsies and biopsy specimens were routinely processed and stained immunohistochemically for CD31, CD34, and vWF. Biopsy material was also stained immunohistochemically for Fli-1, D2-40, and Lyve-1. The expression pattern of the markers was heterogeneous in some of the organs studied. In the kidney, fenestrated endothelium of the glomeruli strongly expressed CD31 and CD34 but was only focally positive or completely negative for vWF. Alveolar wall capillaries of the lung strongly stained for CD31 and CD34 but were usually negative for vWF. The staining intensity for vWF increased gradually with the vessel caliber in the lung. Sinusoids of the spleen and liver were diffusely positive for CD31. They were negative for CD34 in the spleen and only expressed CD34 in the periportal area in the liver. Fli-1 was expressed in all types of EC but also in lymphocytes. D2-40 stained lymphatic endothelium only. Lyve-1 immunostaining was too variable to be applied to routinely processed tissues. The expression of EC markers CD31, CD34, and vWF in the vascular tree is heterogeneous with a specific pattern for individual vessel types and different anatomic compartments of the same organ. D2-40 labels lymphatic EC only.

  17. Is there an evolutionary relationship between WARP (von Willebrand factor A-domain-related protein) and the FACIT and FACIT-like collagens?

    PubMed

    Fitzgerald, Jamie; Bateman, John F

    2003-09-25

    We suggest that there is an evolutionary relationship between von Willebrand factor A-domain-related protein (WARP), and the fibril-associated collagen with interrupted triple helix (FACIT) and FACIT-like subfamilies of collagens. Data from a comparison of amino acid sequences, domain organisation and chromosomal location are consistent with the hypothesis that WARP and these collagens share a common collagen ancestor. In support of this is the observation that the WARP 3' coding region is GC-rich suggesting that this may represent the remnant of a triple helix protein domain which WARP has 'lost' during evolution.

  18. Pif97, a von Willebrand and Peritrophin Biomineralization Protein, Organizes Mineral Nanoparticles and Creates Intracrystalline Nanochambers.

    PubMed

    Chang, Eric P; Evans, John Spencer

    2015-09-01

    The formation of the mollusk nacre layer involves the assembly and organization of mineral nanoparticles into fracture-toughened mesoscale-sized aragonite tablets that possess intracrystalline nanoporosities. At least one nacre protein family, known as the framework proteome, is strategically located as part of a macromolecular coating around each nacre tablet and is believed to participate in tablet formation. Here, we report new studies of a recombinant form (rPif97) of a unique Japanese pearl oyster (Pinctada fucata) nacre framework biomineralization protein, Pif97. This unique protein possesses both a von Willlebrand factor type A domain (vWA, F23-Y161) and a Peritrophin A chitin-binding domain (PAC, E234-D298). rPif97 self-associates or aggregates to form amorphous protein phases that organize both amorphous and single-crystal calcium carbonate nanoparticles in vitro. Further, in the presence of nucleating calcite crystals, rPif97 protein phases deposit onto these crystals and become occluded over time, forming nanochambers within the crystal interior. The formation of these mineral-modifying amorphous protein phases is linked to the presence of intrinsic disorder and amyloid-like cross-β-strand aggregation-prone regions, and three-dimensional modeling indicates that both the vWA and PAC domains are accessible for intermolecular interactions. Thus, the vWA- and PAC-containing Pif97 protein exhibits key functionalities that would allow its participation in mollusk nacre layer tablet assembly and porosity formation.

  19. [Deposition of von Willebrand factor in human endothelial cells HUVEC in the endoplasmic reticulum stress induced by an excess of homocysteine in vitro].

    PubMed

    Ignashkova, T I; Mesitov, M V; Rybakov, A S; Moskovtsev, A A; Sokolovskaia, A A; Kubatiev, A A

    2012-01-01

    Von Willebrand factor (vWF) is an adhesive glycoprotein synthesized and secreted by endothelial cells and megakaryocytes. Violation of vWF secretion by endothelial cells is a characteristic feature of endothelial dysfunction in hyperhomocysteinemia. In our study we examined to clarify the concentration-dependent effect of homocysteine (Hcy) on the expression of vWF. Our studies have shown that homocysteine excess induces changes in the intracellular deposition of von Willebrand factor in cultured human endothelial cells in vitro. Primary cultures of human umbilical vein endothelial cells (HUVEC) were incubated with the various concentrations of D,L-homocysteine (0.025 - 5 mM). Homocysteine at a concentration of 0.025 and 0.25 mM after 18 h incubation caused an increase in the intracellular fraction of vWF in HUVEC cells. High concentrations of homocysteine induced a dose-dependent decrease in the intracellular fraction of vWF. These dose-dependent variations may indicate the modulation by homocysteine of different mechanisms of the deposition, the constitutive secretion and the degradation of vWF in human endothelial cells. We proposed that Endoplasmic reticulum stress, in HUVEC cells by the action of an excess of homocysteine associated with increased intracellular levels of vWF at a relatively low concentration of the inducer. We found decline in intracellular vWF at the same duration but higher concentrations of inducer, which may be due to the ER-associated protein degradation.

  20. Enzymes that hydrolyze adenine nucleotides in platelets and polymorphisms in the alpha2 gene of integrin alpha2beta1 in patients with von Willebrand disease.

    PubMed

    Santos, Karen Freitas; Battisti, Vanessa; Corrêa, Maísa de Carvalho; Mann, Thaís Rapachi; Pereira, Renata da Silva; Araújo, Maria do Carmo; Brülê, Alice Odete; Schetinger, Maria Rosa Chitolina; Morsch, Vera Maria

    2010-07-01

    Von Willebrand disease (VWD) is one of the most common inherited bleeding diseases caused by a qualitative or quantitative deficiency of the von Willebrand factor (FvW). FvW is a multimeric glycoprotein synthesized by megakaryocytes and endothelial cells and it is present in the subendothelial matrix, blood plasma, platelets, and endothelium. This glycoprotein plays an important role in thrombus formation by initiating platelet adhesion to sites of injury as well as platelet aggregation. The aim of this study was to evaluate the activities of enzymes that hydrolyze adenine nucleotides in platelets, ristocetin-induced platelet aggregation (RIPA), and polymorphisms of the alpha2 gene of alpha2beta1 integrin from VWD patients. Platelet nucleoside triphosphate diphosphohydrolase (NTPDase), 5'-nucleotidase, and ecto-nucleotide pyrophosphatase/phosphodiesterase (E-NPP) activities were verified in 14 VWD patients. For RIPA determination, a final concentration of 1.25 mg/ml of ristocetin was used. Polymorphisms of the alpha2 gene were analyzed through PCR. Platelet NTPDase and E-NPP were decreased in VWD patients. 5'-Nucleotidase activity was not statistically significant between controls and VWD patients. RIPA was significantly reduced, with an allelic frequency of 78.57% for 807C in VWD patients. Our results indicated reduced platelet NTPDase and E-NPP activities which might be related to the low platelet adhesiveness. The prevalence of the 807C allele might account for the variability in bleeding in VWD.

  1. Common and rare von Willebrand factor (VWF) coding variants, VWF levels, and factor VIII levels in African Americans: the NHLBI Exome Sequencing Project.

    PubMed

    Johnsen, Jill M; Auer, Paul L; Morrison, Alanna C; Jiao, Shuo; Wei, Peng; Haessler, Jeffrey; Fox, Keolu; McGee, Sean R; Smith, Joshua D; Carlson, Christopher S; Smith, Nicholas; Boerwinkle, Eric; Kooperberg, Charles; Nickerson, Deborah A; Rich, Stephen S; Green, David; Peters, Ulrike; Cushman, Mary; Reiner, Alex P

    2013-07-25

    Several rare European von Willebrand disease missense variants of VWF (including p.Arg2185Gln and p.His817Gln) were recently reported to be common in apparently healthy African Americans (AAs). Using data from the NHLBI Exome Sequencing Project, we assessed the association of these and other VWF coding variants with von Willebrand factor (VWF) and factor VIII (FVIII) levels in 4468 AAs. Of 30 nonsynonymous VWF variants, 6 were significantly and independently associated (P < .001) with levels of VWF and/or FVIII. Each additional copy of the common VWF variants encoding p.Thr789Ala or p.Asp1472His was associated with 6 to 8 IU/dL higher VWF levels. The VWF variant encoding p.Arg2185Gln was associated with 7 to 13 IU/dL lower VWF and FVIII levels. The type 2N-related VWF variant encoding p.His817Gln was associated with 17 IU/dL lower FVIII level but normal VWF level. A novel, rare missense VWF variant that predicts disruption of an O-glycosylation site (p.Ser1486Leu) and a rare variant encoding p.Arg2287Trp were each associated with 30 to 40 IU/dL lower VWF level (P < .001). In summary, several common and rare VWF missense variants contribute to phenotypic differences in VWF and FVIII among AAs.

  2. Biological diagnosis of von Willebrand disease: analytical characteristics of Innovance vWF:Ac assay kit on STA-R Evolution Expert series analyzer (Stago).

    PubMed

    Florin, Cécile; Garraud, Olivier; Molliex, Serge; Tardy, Brigitte; Campos, Lydia; Scherrer, Carine

    2016-06-01

    The Innovance VWF:Ac test (Siemens) has the particularity to assess the binding capacity of von Willebrand factor (VWF) to recombinant platelet GPIb mutated in the absence of ristocetin. Our study aimed to evaluate and validate according to standard NF EN ISO 15189 the original protocol adaptation on STA-R Evolution series analyser (Diagnostica Stago). We evaluated the performance in terms of imprecision and we validate additional parameters necessary in range B as recommended by the SH GTA 04 (Cofrac). We compared the new assay with the reference assay: ristocetin cofactor activity (VWF:RCo) performed on the BCS-XP analyser by testing retrospectively samples from 82 healthy normal subjects and 61 patients with von Willebrand disease (VWD). This new assay is consistent with objectives set in terms of imprecision with CV around 4%. Excepted limit of quantification higher, additional parameters evaluated in range B have been validated. The Innovance VWF: Ac assay allowed the detection of all deficits of VWF already detected by the VWF:RCo test on the BCS-XP. This adjustment on STA-R analyser therefore has satisfactory analytical performance criteria. Apart from the limit of quantification, this reagent can be used according to the recommendations specified in the original protocol adaptation. Its performance and compatibility with the spot measurement allow the diagnosis and therapeutic monitoring of VWD according to current requirements and guidelines.

  3. Pharmacokinetics and safety of a novel recombinant human von Willebrand factor manufactured with a plasma-free method: a prospective clinical trial

    PubMed Central

    Mannucci, Pier Mannuccio; Kempton, Christine; Millar, Carolyn; Romond, Edward; Shapiro, Amy; Birschmann, Ingvild; Ragni, Margaret V.; Gill, Joan Cox; Yee, Thynn Thynn; Klamroth, Robert; Wong, Wing-Yen; Chapman, Miranda; Engl, Werner; Turecek, Peter L.; Suiter, Tobias M.

    2013-01-01

    Safety and pharmacokinetics (PK) of recombinant von Willebrand factor (rVWF) combined at a fixed ratio with recombinant factor VIII (rFVIII) were investigated in 32 subjects with type 3 or severe type 1 von Willebrand disease (VWD) in a prospective phase 1, multicenter, randomized clinical trial. rVWF was well tolerated and no thrombotic events, inhibitors, or serious adverse events were observed. The PK of rVWF ristocetin cofactor activity, VWF antigen, and collagen-binding activity were similar to those of the comparator plasma-derived (pd) VWF-pdFVIII. In vivo cleavage of ultra-large molecular-weight rVWF multimers by ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13; the endogenous VWF protease) and generation of characteristic satellite bands were demonstrated. In 2 subjects with specific nonneutralizing anti-VWF–binding antibodies already detectable before rVWF infusion, a reduction in VWF multimers and VWF activity was observed. Stabilization of endogenous FVIII was enhanced following post–rVWF-rFVIII infusion as shown by the difference in area under the plasma concentration curve compared with pdVWF-pdFVIII (AUC0-∞) (P < .01). These data support the concept of administering rVWF alone once a therapeutic level of endogenous FVIII is achieved. This trial was registered at www.clinicaltrials.gov as #NCT00816660. PMID:23777763

  4. Production and functional activity of a recombinant von Willebrand factor-A domain from human complement factor B.

    PubMed Central

    Williams, S C; Hinshelwood, J; Perkins, S J; Sim, R B

    1999-01-01

    Factor B is a five-domain 90 kDa serine protease proenzyme which is part of the human serum complement system. It binds to other complement proteins C3b and properdin, and is activated by the protease factor D. The fourth domain of factor B is homologous to the type A domain of von Willebrand Factor (vWF-A). A full-length human factor B cDNA clone was used to amplify the region encoding the vWF-A domain (amino acids 229-444 of factor B). A fusion protein expression system was then used to generate it in high yield in Escherichia coli, where thrombin cleavage was used to separate the vWF-A domain from its fusion protein partner. A second vWF-A domain with improved stability and solubility was created using a Cys(267)-->Ser mutation and a four-residue C-terminal extension of the first vWF-A domain. The recombinant domains were investigated by analytical gel filtration, sucrose density centrifugation and analytical ultracentrifugation, in order to show that both domains were monomeric and possessed compact structures that were consistent with known vWF-A crystal structures. This expression system and its characterization permitted the first investigation of the function of the isolated vWF-A domain. It was able to inhibit substantially the binding of (125)I-labelled factor B to immobilized C3b. This demonstrated both the presence of a C3b binding site in this portion of factor B and a ligand-binding property of the vWF-A domain. The site at which factor D cleaves factor B is close to the N-terminus of both recombinant vWF-A domains. Factor D was shown to cleave the vWF-A domain in the presence or absence of C3b, whereas the cleavage of intact factor B under the same conditions occurs only in the presence of C3b. PMID:10477273

  5. Function of von Willebrand factor in children with diarrhea-associated hemolytic-uremic syndrome (D+ HUS).

    PubMed

    Sutor, A H; Thomas, K B; Prüfer, F H; Grohmann, A; Brandis, M; Zimmerhackl, L B

    2001-06-01

    Reports on von Willebrand factor (vWF) in hemolytic-uremic syndrome (HUS) are not unequivocal. Because of potential pathogenic implications, we examined the ability of vWF to bind to collagen in vitro, which reflects its function. Plasma vWF antigen (vWF:Ag) and collagen-binding activity (vWF:CBA) were measured by enzyme-linked immunosorbent assay in children with (1) diarrhea-associated (D+) HUS (n = 27), (2) chronic renal insufficiency (CRI) (n = 8), (3) gastroenteritis (GE) not associated with HUS (n = 15), (4) immune thrombocytopenia (ITP) (n = 40) and from controls (n = 35). Structural vWF was evaluated by multimer analysis. Children with D+ HUS had vWF:Ag of 2.53 and vWF:CBA of 1.98 U/mL. The corresponding values for patients with ITP were 1.35 and 1.82 U/mL, with CRI 1.55 and 1.55 U/mL, and with GE 1.68 and 2.10 U/mL; all values were higher than in controls (1.04 and 1.16 U/mL). The mean ratio of vWF:CBA to vWF:Ag ratio in controls was 1.13; only children with HUS had a dysfunctional vWF, as indicated by a low ratio of 0.78; the ratio was elevated in children with ITP (1.36) and GE (1.27) and was normal in those with CRI (1.06). No ultralarge molecular multimers of vWF were detected in any group, including HUS. The very high concentration of plasma vWF:Ag in HUS probably reflects endothelial cell damage or irritation. In contrast to all other groups, only children with HUS had a dysfunctional vWF, caused either by a primary (due to enterohemorrhagic Escherichia coli) or secondary (due to consumption of functionally active vWF) process. This abnormality was not obvious as structural anomaly by multimer analysis.

  6. Subclinical Atherosclerosis in Patients with Rheumatoid Arthritis and Low Cardiovascular Risk: The Role of von Willebrand Factor Activity

    PubMed Central

    Ristić, Gorica G.; Subota, Vesna; Lepić, Toplica; Stanisavljević, Dejana; Glišić, Branislava; Ristić, Arsen D.; Petronijević, Milan; Stefanović, Dušan Z.

    2015-01-01

    Background To evaluate association between von Willebrand factor (vWF) activity, inflammation markers, disease activity, and subclinical atherosclerosis in patients with rheumatoid arthritis (RA) and low cardiovascular risk. Methods Above mentioned parameters were determined in blood samples of 74 non-diabetic, normotensive, female subjects, with no dyslipidemia(42 patients, 32 matched healthy controls, age 45.3±10.0 vs. 45.2±9.8 years). Intima-media thickness (IMT) was measured bilaterally, at common carotid, bifurcation, and internal carotid arteries. Subclinical atherosclerosis was defined as IMT>IMTmean+2SD in controlsat each carotid level and atherosclerotic plaque as IMT>1.5 mm. Majority of RA patients were on methotrexate (83.3%), none on steroids >10 mg/day or biologic drugs. All findings were analysed in the entire study population and in RA group separately. Results RA patients with subclinical atherosclerosis had higher vWF activity than those without (133.5±69.3% vs. 95.3±36.8%, p<0.05). Predictive value of vWF activity for subclinical atherosclerosis was confirmed by logistic regression. vWF activity correlated significantly with erythrocyte sedimentation rate, fibrinogen, modified disease activity scores (mDAS28–ESR, mDAS28–CRP), modified Health Assessment Questionnaire (p<0.01 for all), duration of smoking, number of cigarettes/day, rheumatoid factor concentration (p<0.05 for all), and anti-CCP antibodies (p<0.01). In the entire study population, vWF activity was higher in participants with subclinical atherosclerosis (130±68% vs. 97±38%, p<0.05) or atherosclerotic plaques (123±57% vs. 99±45%, p<0.05) than in those without. Duration of smoking was significantly associated with vWF activity (β 0.026, p = 0.039). Conclusions We demonstrated association of vWF activity and subclinical atherosclerosis in low-risk RA patients as well as its correlation with inflammation markers, all parameters of disease activity, and seropositivity

  7. Increased von Willebrand factor levels in patients with systemic lupus erythematosus reflect inflammation rather than increased propensity for platelet activation

    PubMed Central

    Raymond, Warren D; Eilertsen, Gro Østli

    2016-01-01

    Background von Willebrand factor (VWF) is involved in platelet plug formation and protein transport. Increased VWF levels in systemic lupus erythematous (SLE) are considered risk factors for vascular events. VWF protein levels, however, do not accurately reflect its platelet-aggregating function, which has not been examined in SLE. Methods Cross-sectional study with clinical and laboratory data obtained in patients with SLE (n=92) from a regional lupus registry. VWF function was determined by ristocetin-induced platelet aggregation (VWF ristocetin cofactor, VWF:RCo) and VWF levels by turbidimetric assay (VWF antigen, VWF:Ag). The platelet-aggregating activity per VWF unit was estimated by the VWF RCo/Ag ratio. Healthy controls served as comparators and associations were evaluated by non-parametric methods. Results VWF:Ag (142% vs 107%, p=0.001) and VWF:RCo levels (123% vs 78%, p<0.041) were increased in patients with SLE, but VWF RCo/Ag ratio was similar as in controls (0.83 vs 0.82, p=0.8). VWF:Ag levels were higher in patients experiencing serositis but unrelated to other manifestations, thrombotic disease, Systemic Lupus Erythematous Disease Activity Index 2000 or Systemic Lupus International Collaborative Clinics-Damage Index. VWF:Ag levels correlated significantly with VWF:RCo levels (Rs 0.8, p<0.001), erythrocyte sedimentation rate (ESR) (Rs 0.32, p<0.01), anti-dsDNA Ab (Rs 0.27, p<0.01), total IgG (Rs 0.33 p<0.01), fibrinogen (Rs 0.28, p<0.01) and ceruloplasmin (Rs 0.367, p<0.01) levels. VWF:RCo levels were not related to clinical findings but were correlated with ESR, anti-dsDNA and transferrin levels. No serological associations existed for VWF RCo/Ag ratio (all p>0.2). Conclusions In this SLE cohort, VWF:Ag behaved similarly to acute-phase reactants, but VWF:Ag increases were not matched by increases in functional activity per unit of VWF. Thus, more VWF did not increase the propensity for platelet aggregation in SLE. PMID:27651919

  8. Le rôle du médecin anesthésiste-réanimateur dans la prise en charge de la femme enceinte porteuse de la maladie de Von Willebrand

    PubMed Central

    Baouahi, Hanane; Zerqouni, Yassine; Doumiri, Mouhcine; Oudghiri, Nezha; Saoud, Anas Tazi

    2015-01-01

    La maladie de Von Willebrand (VWD) est la maladie hémorragique constitutionnelle de l'hémostase la plus fréquente. Elle est liée à un déficit, soit quantitatif, soit qualitatif en facteur willebrand (VWF). Elle se caractérise par son extrême hétérogénéité sur les plans clinique, phénotypique et génotypique. La grossesse et surtout le péri-partum représente une période à risque hémorragique pour ces femmes. Nous rapportons le cas d'une parturiente présentant une maladie de Von Willebrand de type 1 documentée, la difficulté du choix du mode d'accouchement et de la technique anesthésique a été revue. PMID:26977242

  9. THE PAPWORTH PLUG - successful use of high dose fibrinogen concentrate and platelet concentrate in potential life-threatening complication after cardiopulmonary bypass surgery in a patient with Type 2M Vicenza von Willebrand Disease.

    PubMed

    Amerikanou, R; MacDonald, S; Lawrence, K; Large, S; Besser, M W

    2012-07-01

    Anecdotally, fibrinogen concentrate (FC) has been used as a "universal" haemostatic agent in complex post-cardiopulmonary bypass (CPB) coagulopathy. We present a case where FC and two pools of platelets prevented life-threatening bleeding in a patient with moderate von Willebrand Disease (vWD) immediately post CPB.

  10. von Willebrand Factor Test

    MedlinePlus

    ... anything else I should know? A person's ABO blood type affects VWF concentrations. People with type O blood ... up to 25% lower than those with other blood types. Measuring levels of other acute phase reactants such ...

  11. von Willebrand Disease

    MedlinePlus

    ... even a change of clothes in case of accidents. Sometimes, a girl's doctor may prescribe birth control ... situations, like after major surgery or a serious accident. Other medicines, like Amicar, control bleeding by keeping ...

  12. von Willebrand Disease

    MedlinePlus

    ... take aspirin and ibuprofen because they interfere with platelet function and can increase the risk of bleeding. It's ... or fever, since it has no effect on platelet function. Medicines for vWD Some people with more serious ...

  13. Some Effects of Calcium on the Activation of Human Factor VIII/Von Willebrand Factor Protein by Thrombin

    PubMed Central

    Switzer, Mary Ellen; McKee, Patrick A.

    1977-01-01

    When Factor VIII/von Willebrand factor (FVIII/vWF) protein is rechromatographed on 4% agarose in 0.25 M CaCl2, the protein and vWF activity appear in the void volume, but most of the FVIII procoagulant activity elutes later. Recent evidence suggests that the delayed FVIII procoagulant activity is a proteolytically modified form of FVIII/vWF protein that filters anomalously from agarose in 0.25 M CaCl2. To test whether or not thrombin is the protease involved, the effect of 0.25 M CaCl2 on FVIII/vWF and its reaction with thrombin was examined. About 30% of the FVIII procoagulant activity was lost immediately when solutions of FVIII/vWF protein were made 0.25 M in CaCl2. When FVIII in 0.15 M NaCl was activated with 0.04 U thrombin/ml and then made 0.25 M in CaCl2, the procoagulant activity of a broad range of FVIII/vWF protein concentrations remained activated for at least 6 h. But, in 0.25 M CaCl2, the increase in FVIII procoagulant activity in response to thrombin was much more gradual and once activated, the procoagulant activity was stabilized by 0.25 M CaCl2. When thrombin-activated FVIII/vWF protein was filtered on 4% agarose in 0.15 M NaCl, there was considerable inactivation of FVIII procoagulant activity; however, the procoagulant activity that did remain eluted in the void volume. In contrast, when thrombin-activated FVIII/vWF protein was filtered in 0.25 M CaCl2, the FVIII procoagulant activity eluted well after the void volume and remained activated for 6 h. The procoagulant peak isolated by filtering nonthrombin-activated FVIII/vWF protein on agarose in 0.25 M CaCl2 was compared to that isolated from thrombin-activated FVIII/vWF protein. Both procoagulant activity peak proteins had about the same specific vWF activity as the corresponding void volume protein. Before reduction, the sodium dodecyl sulfate gel patterns for the two procoagulant activity peak proteins were the same. After reduction, the gel pattern for the nonthrombin-activated procoagulant

  14. The TITAN trial--assessing the efficacy and safety of an anti-von Willebrand factor Nanobody in patients with acquired thrombotic thrombocytopenic purpura.

    PubMed

    Holz, Josefin-Beate

    2012-06-01

    The Phase II TITAN trial is designed to assess the efficacy and safety of an anti-von Willebrand factor (vWF) Nanobody in patients with acquired thrombotic thrombocytopenic purpura (TTP). Nanobodies are a novel class of therapeutic proteins and are based on the smallest functional fragments of single-chain antibodies that occur naturally in the Camelidae family (Nanobody® and Nanobodies® are registered trademarks of Ablynx NV). With vWF implicated in the thrombotic process underlying TTP, an anti-vWF Nanobody may hold significant promise as adjunctive therapy to plasma exchange. Recruitment is currently ongoing, and aims to include a total of 110 patients from countries in Europe, the Middle East, Australia and Northern America.

  15. Insight into interactions of the von-Willebrand-factor-A-like domain 2 with the FNIII-like domain 9 of collagen VII by NMR and SPR.

    PubMed

    Leineweber, Sarah; Schönig, Sarah; Seeger, Karsten

    2011-06-23

    Type VII collagen as component of anchoring fibrils plays an important role in skin architecture, however, no detailed structural information is available. Here, we describe the recombinant expression, isotope labeling, and (1)H, (15)N, (13)C chemical shift assignment of a subdomain of the murine type VII collagen - the von-Willebrand-factor-A-like domain 2 (mvWFA2). vWFA2 interacts with type I collagen and plays a central role in certain skin blistering diseases. Based on these assignments a secondary structure prediction was performed showing a properly folded protein. An interaction of mvWFA2 with its neighboring domain mFNIII-9 was characterized with NMR spectroscopy and SPR.

  16. Common carotid intima-media thickness and von Willebrand factor serum levels in rheumatoid arthritis female patients without cardiovascular risk factors.

    PubMed

    Daza, Leonel; Aguirre, Martin; Jimenez, Martin; Herrera, Rafael; Bollain, J J

    2007-04-01

    High atherosclerosis prevalence was found in rheumatoid arthritis (RA), and the von Willebrand factor (vWF) was shown to be a marker for endothelial damage. The aim of this study was to evaluate the association of intima-media thickness of the left common carotid artery with vWF serum levels in rheumatoid arthritis patients without cardiovascular risk factors. We included 55 RA female patients, each with at least 5 years of duration of the disease, and 20 healthy female subjects as members of the control group. The vWF, cholesterol, triglycerides, and the immune variables-rheumatoid factor and reactive C protein-were evaluated. The media thickness and intima-media thickness (IMT) in patients and in the control subjects were assessed by Doppler ultrasound of the left common carotid artery. Although the ages for RA patients and healthy female controls were not different, the IMT of the left common carotid artery (IMT CCA) in rheumatoid arthritis patients was increased in comparison with healthy control measurements, the mean being 0.67 mm (SD 0.18) vs 0.58 mm (SD 0.10) with a p value 0.01. The vWF serum levels showed differences in RA patients from those in control patients, 145.6 (SD 30.08) vs 121.8 (SD 37.17), respectively, with p=0.007. A correlation was also found between vWF with IMT CCA in the RA patients: r=0.390 and p<0.05. We concluded that the measurements of the left common carotid artery intima-media thickness together with the von Willebrand factor serum levels could give valuable information about the artery status and the atherosclerosis process in early stages in patients with rheumatoid arthritis without cardiovascular risk factors.

  17. Selection on cis-Regulatory Variation at B4galnt2 and Its Influence on von Willebrand Factor in House Mice

    PubMed Central

    Johnsen, Jill M.; Teschke, Meike; Pavlidis, Pavlos; McGee, Beth M.; Tautz, Diethard; Baines, John F.

    2009-01-01

    The RIIIS/J inbred mouse strain is a model for type 1 von Willebrand disease (VWD), a common human bleeding disorder. Low von Willebrand factor (VWF) levels in RIIIS/J are due to a regulatory mutation, Mvwf1, which directs a tissue-specific switch in expression of a glycosyltransferase, B4GALNT2, from intestine to blood vessel. We recently found that Mvwf1 lies on a founder allele common among laboratory mouse strains. To investigate the evolutionary forces operating at B4galnt2, we conducted a survey of DNA sequence polymorphism and microsatellite variation spanning the B4galnt2 gene region in natural Mus musculus domesticus populations. Two divergent haplotypes segregate in these natural populations, one of which corresponds to the RIIIS/J sequence. Different local populations display dramatic differences in the frequency of these haplotypes, and reduced microsatellite variability near B4galnt2 within the RIIIS/J haplotype is consistent with the recent action of natural selection. The level and pattern of DNA sequence polymorphism in the 5′ flanking region of the gene significantly deviates from the neutral expectation and suggests that variation in B4galnt2 expression may be under balancing selection and/or arose from a recently introgressed allele that subsequently increased in frequency due to natural selection. However, coalescent simulations indicate that the heterogeneity in divergence between haplotypes is greater than expected under an introgression model. Analysis of a population where the RIIIS/J haplotype is in high frequency reveals an association between this haplotype, the B4galnt2 tissue-specific switch, and a significant decrease in plasma VWF levels. Given these observations, we propose that low VWF levels may represent a fitness cost that is offset by a yet unknown benefit of the B4galnt2 tissue-specific switch. Similar mechanisms may account for the variability in VWF levels and high prevalence of VWD in other mammals, including humans. PMID

  18. The diagnostic dilemma: dual presentations of clinical mucosal bleeding and venous thrombosis associated with the presence of thrombophilia markers and mild reduction in von Willebrand factor.

    PubMed

    Favaloro, Emmanuel J; Bonar, Roslyn; Survela, Lesley; McDonald, David; Koutts, Jerry; Sioufi, John; Marsden, Katherine

    2007-01-01

    A prothrombotic and hemorrhagic state can separately manifest in one patient and can potentially cause several diagnostic problems. We report an intriguing case as an example of a potential hemostasis-based diagnostic dilemma. A 29-year-old female patient presented with a personal history of menorrhagia and other mucosal bleeding and renal ovarian thrombosis. Previous investigations had uncovered several diagnostic anomalies, including von Willebrand disease (VWD), factor V Leiden (FVL), antiphospholipid syndrome, and thrombocytopaenia. Previous therapy in this patient included heparin and warfarin for the thrombosis and desmopressin acetate (DDAVP) and antifibrinolytic therapy for surgical management. Subsequent laboratory testing with fresh samples consistently confirmed an equivocal (borderline normal/abnormal) level of von Willebrand factor (VWF) and FVL with activated protein C resistance (APCR). A patient sample, differentially labeled according to the tests being performed, was later distributed for blind testing to participants within several modules of the RCPA Quality Assurance Program (QAP). Most participants reported a low level of VWF consistent with possible mild Type 1 VWD, and most (but not all) reported a positive finding for APCR. All participants correctly reported the sample as heterozygous for the FVL mutation, negative for the Prothrombin gene mutation G20210A, and heterozygous for the methylenetetrahydrofolate reductase (MTHFR) mutation C677T. Interestingly, a significant number of laboratories performing Protein S testing using clot-based procedures also identified a false Protein S deficiency. In conclusion, this exercise showed how, either depending on the clinical review and specific laboratory investigation and tests performed, a pro-bleeding diagnosis (of either VWD or thrombocytopenia) or pro-thrombophilia risk (Antiphospholipid Syndrome or FVL/APCR or false Protein S deficiency) could potentially and differentially arise in the one

  19. An update on the von Willebrand factor collagen binding assay: 21 years of age and beyond adolescence but not yet a mature adult.

    PubMed

    Favaloro, Emmanuel J

    2007-11-01

    von Willebrand disease (VWD) is considered to be the most common inherited bleeding disorder. It is diagnosed after a clinical and physical review, with personal and familial evidence of (primarily mucocutaneous) bleeding, and confirmed by laboratory testing. The latter typically entails initial plasma testing of factor VIII coagulant (FVIII:C), von Willebrand factor (VWF) protein (antigen; VWF:Ag), and VWF function, which has classically been assessed using the ristocetin cofactor (VWF:RCo) assay. More recent attention has focused on another functional VWF assay, the collagen binding (VWF:CB) assay, as a possible replacement for the VWF:RCo assay or as a supplementary test of VWF adhesive "activity." Additional laboratory testing can comprise a battery of confirmatory and VWD subtype assisting assays, including assessment of VWF:multimers. This review updates our knowledge of VWD diagnostics with a particular emphasis on the VWF:CB assay. There is good evidence now in place that an optimized VWF:CB assay can significantly reduce the diagnostic error rate otherwise arising from the use of a test panel restricted to including the VWF:RCo assay as the sole functional VWF assay. Nevertheless, the VWF:CB assay should not be used to wholly replace the VWF:RCo assay in phenotypic testing but rather as a supplementary assay. However, with some thought and justification, the VWF:CB assay can be used to partly replace the VWF:RCo assay in some "screening" applications and can also be used to abrogate the need to perform routine VWF:multimers in most test cases.

  20. Crystallization and preliminary X-ray analysis of the complex of the first von Willebrand type C domain bound to bone morphogenetic protein 2

    SciTech Connect

    Qiu, Li-yan; Zhang, Jin-li; Kotzsch, Alexander; Sebald, Walter; Mueller, Thomas D.

    2008-04-01

    Crystals of the complex of the first von Willebrand type C domain (VWC1) of crossveinless 2 (CV2) bound to bone morphogenetic protein 2 (BMP2) exist in two tetragonal crystal forms belonging to either space group P4{sub 1}2{sub 1}2 or I4{sub 1}, with one complete BMP2 dimer and two CV2 VWC1 domains per asymmetric unit, and diffract to 2.6 Å resolution. Crossveinless 2 (CV2) is a member of the chordin family, a protein superfamily that modulates the activity of bone morphogenetic proteins such as BMP2. The BMPs represent a large group of secreted proteins that control many steps during embryonal development and in tissue and organ homeostasis in the adult organism. The gene encoding the first von Willebrand type C domain (VWC1) of CV2 was cloned, expressed in Escherichia coli and purified to homogeneity. The binary complex of CV2 VWC1 and BMP2 was purified and subjected to crystallization. Crystals of SeMet-labelled proteins were obtained in two different forms belonging to the tetragonal space groups P4{sub 1}2{sub 1}2 and I4{sub 1}, with unit-cell parameters a = b = 86.7, c = 139.2 Å and a = b = 83.7, c = 139.6 Å, respectively. Initial analysis suggests that a complete binary complex consisting of one BMP2 dimer bound to two CV2 VWC1 domains is present in the asymmetric unit.

  1. The p.R1819_C1948delinsS mutation makes von Willebrand factor ADAMTS13-resistant and reduces its collagen-binding capacity.

    PubMed

    Daidone, Viviana; Saga, Giorgia; Barbon, Giovanni; Pontara, Elena; Cattini, Maria G; Morpurgo, Margherita; Zanotti, Giuseppe; Casonato, Alessandra

    2015-08-01

    This report concerns abnormal ADAMTS13 (a disintegrin and metalloprotease with a thrombospondin type 1 motif, member 13) and collagen interactions coinciding with the p.R1819_C1948delinsS von Willebrand factor (VWF) mutation associated with the deletion of the C-terminus of the A3 domain (amino acids 1819-1947) in a patient with a history of bleeding. The von Willebrand disease (VWD) phenotype of the patient featured low plasma and platelet VWF, multimers with smears extending over the highest normal oligomers in plasma, but not platelets, and an impaired collagen-binding capacity. In vitro full-length p.R1819_C1948delinsS VWF expression showed impaired VWF release, increased cellular content with normally-multimerized VWF and impaired collagen binding. The recombinant p.R1819_C1948delinsS VWF fragment, extending from domains A2 to B3 (p.R1819_C1948delinsS A2-B3 VWF), was completely resistant to proteolysis by ADAMTS13 in the presence of 1·5 mol/l urea, unlike its normal counterpart. The defect stems from impaired ADAMTS13 binding to p.R1819_C1948delinsS A2-B3, analysed under static conditions. Partial deletion of the C-terminus of the A3 domain thus makes VWF resistant to ADAMTS13, interfering with ADAMTS13 binding to VWF, and impairing the collagen-binding capacity of VWF. The p.R1819_C1948delinsS mutation has both haemorrhagic features (defective collagen binding, reduced VWF levels) and prothrombotic (ADAMTS13 resistance) features, and the latter probably mitigate the patient's bleeding symptoms.

  2. Phenotypic Parameters in Genotypically Selected Type 2B von Willebrand Disease Patients: A Large, Single-Center Experience Including a New Novel Mutation.

    PubMed

    Woods, Adriana Ines; Kempfer, Ana Catalina; Paiva, Juvenal; Sanchez-Luceros, Analia; Bermejo, Emilse; Chuit, Roberto; Alberto, Maria Fabiana; Blanco, Alicia Noemi; Lazzari, Maria Angela

    2017-02-01

    von Willebrand disease type 2B (VWD2B) expresses gain-of-function mutations that enhance binding of an individual's von Willebrand factor (VWF) to its platelet ligand, glycoprotein Ib (GPIb), and which are usually identified by increased ristocetin-induced platelet aggregation (RIPA). We describe here the phenotypic profile of 38 genotypically selected VWD2B-affected family members (AFMs) belonging to 19 unrelated families. Major bleeding was observed in 68.4% of AFMs (previous to their diagnosis and registered by lifetime interviews), with a total of 46 episodes (1.21/patient), and was found to be highly related to the individual bleeding score and presence of thrombocytopenia, but otherwise unrelated to other laboratory parameters. Excessive muco-cutaneous bleeding symptoms were often reported, the most frequent of which comprised menorrhagia, epistaxis, easy bruising, and bleeding after teeth extraction/in oral cavity. Eight unaffected family members were also studied. The prevalence of VWD2B within families was 0.826, and the penetrance of mutations was complete, making it mandatory to study entire family sets to complete diagnostic profiles. Seven heterozygous missense mutations were found, the most common being p.V1316M. In the p.R1308C group, 75% of the AFMs showed absence of RIPA at 0.5 mg/mL, 66.6% of whom had VWF:RCo < 10 IU/dL, and 50% of whom had VWF:CB < 10 IU/dL. In the p.S1310F group, none of the AFMs had VWF:RCo/VWF:Ag < 0.6 (RCo/Ag), but 100% had VWF:CB/VWF:Ag < 0.6/(CB/Ag). Patients with p.P1266L and p.R1304V were characterized as atypical VWD2B. Two de novo mutations were found in four AFMs belonging to two families. We also describe a novel mutation: p.Y1258C. Of our patients, 70.5% had O blood group. In conclusion, a normal RCo/Ag and a negative RIPA at 0.5 mg/mL do not necessarily rule out a diagnosis of VWD2B.

  3. Human marrow megakaryocyte differentiation: multiparameter correlative analysis identifies von Willebrand factor as a sensitive and distinctive marker for early (2N and 4N) megakaryocytes.

    PubMed

    Tomer, Aaron

    2004-11-01

    Human megakaryocyte differentiation and maturation were studied in fresh marrow aspirates by using multiparameter flow cytometric correlative analysis. The expression of glycoprotein (GP)IIb/IIIa, GPIIIa, GPIb, and CD36 correlated directly with cell size and ploidy (r > 0.97); however, GPIb acquisition was relatively slow. von Willebrand factor (VWF) is robustly expressed by early (2N and 4N) megakaryocytes, enabling their complete resolution from the other marrow cells at a level superior to that achieved with GPIIb/IIIa. Expression of myeloid CD45 and immunoglobulin G (IgG)-FcgammaRII receptor (CDw32) increased with megakaryocyte maturation and contrasted with the declining expression of HLA-DR (negative in platelets). Interleukin-6 receptor expression in megakaryocytes was higher than in other marrow cells. By using the time-of-flight technique, the diameter of the megakaryocyte population was 37 +/- 4 microm (mean +/- 1 SD) compared with 14 +/- 2 microm for the total marrow cells, ranging from 21 +/- 4 microm for 2N cells to 56 +/- 8 microm for 64N cells. Cell size directly correlated with cell DNA (r = 0.98). Receptor density of GPIIb/IIIa and GPIb decreased with the transition from 2N to 4N cells, then reached maximum at 32N cells. In conclusion, the present methods are useful for studying in vivo human megakaryocytopoiesis in normal and altered states. The expression of VWF is a sensitive and distinctive marker for the identification of young marrow megakaryocytes.

  4. A new extracellular von Willebrand A domain-containing protein is involved in silver uptake in Microcystis aeruginosa exposed to silver nanoparticles.

    PubMed

    Chen, Si; Jin, Yujian; Lavoie, Michel; Lu, Haiping; Zhu, Kun; Fu, Zhengwei; Qian, Haifeng

    2016-10-01

    Silver nanoparticles (AgNPs) can be toxic for cyanobacteria when present at low nanomolar concentrations, but the molecular mechanisms whereby AgNPs (or free Ag(+) released from AgNPs) interact with these prokaryotic algal cells remain elusive. Here, we studied Ag uptake mechanisms in the prokaryotic cyanobacterium Microcystis aeruginosa exposed to AgNPs by measuring growth inhibition in the absence or presence of high-affinity Ag-binding ligands and by genetic transformation of E. coli with a protein predicted to be involved in Ag uptake. We discovered a new von Willebrand A (vWA) domain-containing protein in M. aeruginosa that mediates Ag uptake from AgNPs when expressed in E. coli. This new Ag transport protein, which is absent in eukaryotic algae, is a potential candidate explaining the higher AgNPs toxicity in cyanobacteria such as M. aeruginosa than that in eukaryotic algae. The present study provides new insights on Ag uptake mechanisms in the prokaryotic algae M. aeruginosa.

  5. Aegyptin, a Novel Mosquito Salivary Gland Protein Specifically Binds to Collagen and Prevents its Interaction with Glycoprotein VI, Integrin α2β1 and von Willebrand Factor

    PubMed Central

    Calvo, Eric; Tokumasu, Fuyuki; Marinotti, Osvaldo; Villeval, Jean-Luc; Ribeiro, José M. C.; Francischetti, Ivo M. B.

    2010-01-01

    Blood-sucking arthropods have evolved a number of inhibitors of platelet aggregation and blood coagulation. In this report we have molecularly and functionally characterized aegyptin, a member of the family of 30-kDa salivary allergens from Aedes aegypti, whose function remained elusive thus far. Aegyptin displays a unique sequence characterized by glycine, glutamic acid, and aspartic acid repeats and was shown to specifically block collagen-induced human platelet aggregation and granule secretion. Plasmon resonance experiments demonstrate that aegyptin binds to collagen types I-V (Kd ≈ 1 nM) but does not interact with vitronectin, fibronectin, laminin, fibrinogen, and von Willebrand factor (vWf). In addition, aegyptin attenuates platelet adhesion to soluble or fibrillar collagen. Furthermore, aegyptin inhibits vWf interaction with collagen type III under static conditions and completely blocks platelet adhesion to collagen under flow conditions at high shear rates. Notably, aegyptin completely prevents collagen but not convulxin binding to recombinant glycoprotein VI. These findings indicate that aegyptin recognizes specific binding sites for glycoprotein VI, integrin α2β1, and vWf, thereby preventing collagen interaction with its three major ligands. Aegyptin is a novel tool to study collagen-platelet interaction and a prototype for development of molecules with antithrombotic properties. PMID:17650501

  6. Rapid Restoration of Thrombus Formation and High-Molecular-Weight von Willebrand Factor Multimers in Patients with Severe Aortic Stenosis After Valve Replacement

    PubMed Central

    Yamashita, Keigo; Yagi, Hideo; Hayakawa, Masaki; Abe, Takehisa; Hayata, Yoshihiro; Yamaguchi, Naoko; Sugimoto, Mitsuhiko; Fujimura, Yoshihiro; Taniguchi, Shigeki

    2016-01-01

    Aim: Patients with severe aortic stenosis (AS) may have bleeding episodes due to the loss of high-molecular-weight (HMW) von Willebrand factor multimers (VWFMs). The absence of HMW-VWFMs and bleeding tendency are usually corrected after aortic valve replacement (AVR). To investigate the process of VWFM recovery and symptoms in patients with severe AS, we analyzed changes in VWF antigen (VWF:Ag), ADAMTS13 activity (ADAMTS13:AC), and platelet thrombus formation under high shear stress conditions. Methods: Nine patients with severe AS undergoing AVR were analyzed. Results: Evident deficiency of HMW-VWFMs was observed in six patients before surgery, which was rapidly restored within 8 days after AVR. Median levels of VWF:Ag before surgery, on postoperative days (PODs) 1, 8, 15, and 22, and one year after AVR were 78.1%, 130%, 224%, 155%, 134%, and 142%, respectively. In contrast, ADAMTS13:AC was 50.5%, 35.5%, 25.5%, 25.1%, 30.3%, and 84.6%, respectively. Preoperative thrombus formation but not surface coverage was significantly lower than that on POD 22, which was considered as normal level in each patient. Compared with preoperative levels, thrombus volume was significantly lower on POD 1, but rapidly increased by POD 8. Conclusion: Bleeding tendency and loss of HMW-VWFMs observed in patients with severe AS before surgery was rapidly corrected after AVR. Instead, patients were in a VWF-predominant state between POD 8 and 22. PMID:27052664

  7. Prophylactic fresh frozen plasma may prevent development of hepatic VOD after stem cell transplantation via ADAMTS13-mediated restoration of von Willebrand factor plasma levels.

    PubMed

    Matsumoto, M; Kawa, K; Uemura, M; Kato, S; Ishizashi, H; Isonishi, A; Yagi, H; Park, Y-D; Takeshima, Y; Kosaka, Y; Hara, H; Kai, S; Kanamaru, A; Fukuhara, S; Hino, M; Sako, M; Hiraoka, A; Ogawa, H; Hara, J; Fujimura, Y

    2007-08-01

    We initially conducted a multicenter, randomized trial (n=43), and subsequently a questionnaire study (n=209) of participating hospitals, to evaluate whether infused fresh frozen plasma (FFP) could prevent the occurrence of hepatic veno-occlusive disease (VOD) after stem cell transplantation (SCT). Forty-three patients were divided into two groups: 23 receiving FFP infusions and 20 not receiving it. VOD developed in three patients not receiving FFP. Plasma von Willebrand factor (VWF) antigen levels were lower at days 0, 7 and 28 after SCT in patients receiving FFP than in those not receiving it, whereas plasma ADAMTS13 activity (ADAMTS13:AC) did not differ between them. Plasma VWF multimer (VWFM) was demonstrated to be defective in the high approximately intermediate VWFM during the early post-SCT phase, but there was a significant increase in high VWFM just before VOD onset. This suggests that a relative enzyme-to-substrate (ADAMTS13/high-VWFM) imbalance is involved in the pathogenesis of VOD. To strengthen this hypothesis, the incidence of VOD was apparently lower in patients receiving FFP infusions than in those not receiving it (0/23 vs 3/20) in the randomized trial. Further, the results combined with the subsequent questionnaire study (0/36 vs 11/173) clearly showed the incidence to be statistically significant (0/59 vs 14/193, P=0.033).

  8. Single particle tracking of ADAMTS13 (a disintegrin and metalloprotease with thrombospondin type-1 repeats) molecules on endothelial von Willebrand factor strings.

    PubMed

    De Ceunynck, Karen; Rocha, Susana; De Meyer, Simon F; Sadler, J Evan; Uji-i, Hiroshi; Deckmyn, Hans; Hofkens, Johan; Vanhoorelbeke, Karen

    2014-03-28

    von Willebrand factor (VWF) strings are removed from the endothelial surface by ADAMTS13 (a disintegrin and metalloprotease with thrombospondin type-1 repeats)-mediated proteolysis. To visualize how single ADAMTS13 molecules bind to these long strings, we built a customized single molecule fluorescence microscope and developed single particle tracking software. Extensive analysis of over 6,000 single inactive ADAMTS13(E225Q) enzymes demonstrated that 20% of these molecules could be detected in at least two consecutive 60-ms frames and followed two types of trajectories. ADAMTS13(E225Q) molecules either decelerated in the vicinity of VWF strings, whereas sometimes making brief contact with the VWF string before disappearing again, or readily bound to the VWF strings and this for 120 ms or longer. These interactions were observed at several sites along the strings. Control experiments using an IgG protein revealed that only the second type of trajectory reflected a specific interaction of ADAMTS13 with the VWF string. In conclusion, we developed a dedicated single molecule fluorescence microscope for detecting single ADAMTS13 molecules (nm scale) on their long, flow-stretched VWF substrates (μm scale) anchored on living cells. Comprehensive analysis of all detected enzymes showed a random interaction mechanism for ADAMTS13 with many available binding sites on the VWF strings.

  9. Quantitative Influence of ABO Blood Groups on Factor VIII and Its Ratio to von Willebrand Factor, Novel Observations from an ARIC Study of 11,673 Subjects.

    PubMed

    Song, Jaewoo; Chen, Fengju; Campos, Marco; Bolgiano, Doug; Houck, Katie; Chambless, Lloyd E; Wu, Kenneth K; Folsom, Aaron R; Couper, David; Boerwinkle, Eric; Dong, Jing-fei

    2015-01-01

    ABO blood groups are known to influence the plasma level of von Willebrand factor (VWF), but little is known about the relationship between ABO and coagulation factor VIII (FVIII). We analyzed the influence of ABO genotypes on VWF antigen, FVIII activity, and their quantitative relationship in 11,673 participants in the Atherosclerosis Risk in Communities (ARIC) study. VWF, FVIII, and FVIII/VWF levels varied significantly among O, A (A1 and A2), B and AB subjects, and the extent of which varied between Americans of European (EA) and African (AA) descent. We validated a strong influence of ABO blood type on VWF levels (15.2%), but also detected a direct ABO influence on FVIII activity (0.6%) and FVIII/VWF ratio (3.8%) after adjustment for VWF. We determined that FVIII activity changed 0.54% for every 1% change in VWF antigen level. This VWF-FVIII relationship differed between subjects with O and B blood types in EA, AA, and in male, but not female subjects. Variations in FVIII activity were primarily detected at low VWF levels. These new quantitative influences on VWF, FVIII and the FVIII/VWF ratio help understand how ABO genotypes differentially influence VWF, FVIII and their ratio, particularly in racial and gender specific manners.

  10. von Willebrand factor is the most reliable immunohistochemical marker for megakaryocytes of myelodysplastic syndrome and chronic myeloproliferative disorders.

    PubMed

    Chuang, S S; Jung, Y C; Li, C Y; Yung, Y C

    2000-04-01

    To find the best immunohistochemical marker for megakaryocytes in normal marrow, myelodysplastic syndrome (MDS), and chronic myeloproliferative disorders (CMPD), 57 marrow biopsy specimens were studied semiquantitatively with immunohistochemical methods using a panel of 7 antibodies. The staining intensity was graded 0 to 3 for scoring 100 consecutive megakaryocytes in each stained section. The final score for each stain was the sum of these 100 megakaryocytes individually multiplied by their corresponding grade. In normal marrow (11 cases), the average scores for antivon Willebrand factor (vWF) and Ulex europaeus agglutinin-1 (UEA-1) were 177.1 and 195.1, respectively. The scores for the other 5 markers, including anti-platelet-derived growth factor-BB, 2 anti-transforming growth factor-beta 3, anti-CD61, and anti-CD79a ranged from 96.1 to 124.1. In MDS (27 cases), the scores were 200.8 (vWF), 152.6 (UEA-1), and 28.7 to 98.5 (others). In CMPD (19 cases), the scores were 220.5 (vWF), 179.2 (UAE-1), and 64.8 to 101.2 (others). These results show that vWF and UEA-1 are good immunohistochemical markers for megakaryocytes in normal marrow, and vWF is the best marker in MDS and CMPD. For routine practice, vWF is the most reliable marker for identifying atypical megakaryocytes, especially in the cases of 5q-syndrome and agnogenic myeloid metaplasia.

  11. P-selectin mRNA is expressed at a later phase of megakaryocyte maturation than mRNAs for von Willebrand factor and glycoprotein Ib-alpha.

    PubMed

    Schick, P K; Konkle, B A; He, X; Thornton, R D

    1993-05-01

    The assembly of alpha-granules occurs exclusively in megakaryocytes because platelets have limited capacity for the synthesis of macromolecules. Thus far, alpha-granule development in megakaryocytes has been primarily evaluated by ultrastructural studies. The aim of the study was to obtain molecular and biochemical evidence for the expression of selected alpha-granule proteins in megakaryocytes. Guinea pig megakaryocytes were purified and separated into subgroups at different phases of maturation by the Celsep procedure (Schick et al. Blood 1989;73:1801-8). Guinea pig-specific probes for P-selectin, von Willebrand factor (vWF), glycoprotein Ib-alpha (GpIb-alpha), and phosphoglycerate kinase were prepared by using the polymerase chain reaction. By Northern blot analysis, P-selectin messenger ribonucleic acid (mRNA) was primarily expressed in the mature megakaryocyte Celsep subgroup, whereas vWF and GpIb-alpha mRNA were expressed at all phases of megakaryocyte maturation. In situ hybridization confirmed that P-selectin mRNA was primarily expressed at later stages of cytoplasmic maturation: 14% +/- 6.2% of stage I, 35.5% +/- 6.1% of stage II, 72% +/- 5.2% of stage III, and 47.0% +/- 3.3% of stage IV megakaryocytes expressed P-selectin mRNA. Thus, the expression of mRNA for P-selectin appeared to peak in stage III cells. In contrast vWF mRNA was expressed in immature megakaryocytes and persisted throughout megakaryocyte maturation. In situ hybridization did not demonstrate a relationship between the expression of mRNA for P-selectin or vWF with megakaryocyte ploidy.(ABSTRACT TRUNCATED AT 250 WORDS)

  12. Hematopoietic factor-induced synthesis of von Willebrand factor by the Dami human megakaryoblastic cell line and by normal human megakaryocytes.

    PubMed

    Greenberg, S M; Chandrasekhar, C

    1991-01-01

    Identification of hemopoietic factors and the molecular mechanisms by which they regulate the various stages of megakaryocyte development and platelet protein expression has been hampered by the lack of a purified, self-renewing, and responsive biological assay system. Previously, the human megakaryocytic Dami cell line has been shown to differentiate in response to phorbol ester by increasing the expression of platelet membrane glycoproteins Ib, IIb/IIIa, and the platelet protein, von Willebrand Factor (vWF). In this report, we demonstrate that this cell line is a suitable model for investigating the effects of specific cytokines and hemopoietic factors on the terminal differentiation of megakaryocytes as measured by the stimulated biosynthesis of vWF in serum-free culture. Although a low concentration (10 U/ml) of purified recombinant interleukin 3 (IL-3) had no effect, a higher concentration (100 U/ml) stimulated a three- to four fold increase in vWF synthesis. Purified thrombopoiesis-stimulating factor (TSF) alone induced a two- to threefold increase, and when used in combination with 10 U/ml IL-3, TSF induced a synergistic five- to sixfold increase in vWF synthesis. Recombinant erythropoietin (EPO) and human interleukin 6 (IL-6) each induced a twofold increase in vWF, and each acted additively with 10 U/ml IL-3. IL-3 and TSF stimulated similar increases in vWF expression by human megakaryocytes contained in nonadherent bone marrow preparations. These results demonstrate the usefulness of the Dami cell line as a serum-free culture system in which to study the direct effects of purified humoral factors on megakaryocyte and platelet protein synthesis during megakaryocyte maturation.

  13. Oxidation of Met1606 in von Willebrand factor is a risk factor for thrombotic and septic complications in chronic renal failure.

    PubMed

    De Filippis, Vincenzo; Lancellotti, Stefano; Maset, Fabio; Spolaore, Barbara; Pozzi, Nicola; Gambaro, Giovanni; Oggianu, Laura; Calò, Lorenzo A; De Cristofaro, Raimondo

    2012-03-01

    CKD (chronic kidney disease) is a life-threatening pathology, often requiring HD (haemodialysis) and characterized by high OS (oxidative stress), inflammation and perturbation of vascular endothelium. HD patients have increased levels of vWF (von Willebrand factor), a large protein (~240 kDa) released as UL-vWF (ultra large-vWF polymers, molecular mass ~20000-50000 kDa) from vascular endothelial cells and megakaryocytes, and responsible for the initiation of primary haemostasis. The pro-haemostatic potential of vWF increases with its length, which is proteolytically regulated by ADAMTS-13 (a disintegrin and metalloproteinase with thrombospondin motifs 13), a zinc-protease cleaving vWF at the single Tyr1605-Met1606 bond, and by LSPs (leucocyte serine proteases), released by activated PMNs (polymorphonuclear cells) during bacterial infections. Previous studies have shown that in vitro oxidation of Met1606 hinders vWF cleavage by ADAMTS-13, resulting in the accumulation of UL-vWF that are not only more pro-thrombotic than shorter vWF oligomers, but also more efficient in binding to bacterial adhesins during sepsis. Notably, HD patients have increased risk of developing dramatic cardiovascular and septic complications, whose underlying mechanisms are largely unknown. In the present study, we first purified vWF from HD patients and then chemically characterized its oxidative state. Interestingly, HD-vWF contains high carbonyl levels and increased proportion of UL-vWF polymers that are also more resistant to ADAMTS-13. Using TMS (targeted MS) techniques, we estimated that HD-vWF contains >10% of Met1606 in the sulfoxide form. We conclude that oxidation of Met1606, impairing ADAMTS-13 cleavage, results in the accumulation of UL-vWF polymers, which recruit and activate platelets more efficiently and bind more tightly to bacterial adhesins, thus contributing to the development of thrombotic and septic complications in CKD.

  14. Expression of Von Willebrand factor, an endothelial cell marker, is up-regulated by angiogenesis factors: a potential method for objective assessment of tumor angiogenesis.

    PubMed

    Zanetta, L; Marcus, S G; Vasile, J; Dobryansky, M; Cohen, H; Eng, K; Shamamian, P; Mignatti, P

    2000-01-15

    von Willebrand factor (vWF), a glycoprotein produced uniquely by endothelial cells and megakaryocytes, is routinely used to identify vessels in tissue sections. Vessel density in tumor specimens, as determined by immuno-histochemical staining for vWF or other endothelial cell markers, is a negative prognostic factor for many solid tumors. vWF is heterogeneously distributed throughout the vasculature, transcriptional control in response to the tissue microenvironment being responsible for local variations in endothelial cell levels of vWF. Here, we report that fibroblast growth factor-2 and vascular endothelial growth factor, potent angiogenesis inducers expressed in a variety of tumors, up-regulate expression of vWF mRNA and protein in cultured endothelial cells with a synergistic effect. Our data support the measurement of vWF mRNA in tumors to detect activated endothelium or angiogenesis. For this purpose, we developed a semi-quantitative RT-PCR for vWF mRNA. Preliminary results obtained with specimens from colon carcinoma and the corresponding normal colonic mucosa showed higher vWF mRNA levels in most tumors than in their normal counterparts. The differences in vWF mRNA levels were much larger than the differences in vessel counts between a tumor and the corresponding normal mucosa, indicating that high vWF mRNA levels in tumors may indeed be an early sign of activation of the endothelium. The rapidity, objectivity, sensitivity and specificity of this technique make it suitable for routine clinical application to identify aggressive, highly angiogenic tumors.

  15. Preserved Expression of mRNA Coding von Willebrand Factor–Cleaving Protease ADAMTS13 by Selenite and Activated Protein C

    PubMed Central

    Ekaney, Michael L; Bockmeyer, Clemens L; Sossdorf, Maik; Reuken, Philipp A; Conradi, Florian; Schuerholz, Tobias; Blaess, Markus F; Friedman, Scott L; Lösche, Wolfgang; Bauer, Michael; Claus, Ralf A

    2015-01-01

    In sepsis, the severity-dependent decrease of von Willebrand factor (VWF)–inactivating protease, a disintegrin and metalloproteinase with thrombospondin motifs 13 (ADAMTS13), results in platelet aggregation and consumption, leading to sepsis-associated thrombotic microangiopathy (TMA) and organ failure. Previous reports assessing its functional deficiency have pinpointed involvement of autoantibodies or mutations to propagate thrombotic thrombocytopenic purpura (TTP). However, mechanisms of acquired ADAMTS13 deficiency during host response remain unclear. To enhance understanding of ADAMTS13 deficiency in sepsis, we evaluated changes in expression of mRNA coding ADAMTS13 during septic conditions using primary cellular sources of the protease. We hypothesized that proinflammatory cytokines and constituents of serum from septic patients affect the transcriptional level of ADAMTS13 in vitro, and previously recommended therapeutic agents as adjunctive therapy for sepsis interact therewith. Cultured hepatic stellate cells (HSCs), endothelial cells (HMEC) and human precision-cut liver slices as an ex vivo model were stimulated with sepsis prototypic cytokines, bacterial endotoxin and pooled serum obtained from septic patients. Stimulation resulted in a significant decrease in ADAMTS13 mRNA between 10% and 80% of basal transcriptional rates. Costimulation of selenite or recombinant activated protein C (APC) with serum prevented ADAMTS13 decrease in HSCs and increased ADAMTS13 transcripts in HMEC. In archived clinical samples, the activity of ADAMTS13 in septic patients treated with APC (n = 5) increased with an accompanying decrease in VWF propeptide as surrogate for improved endothelial function. In conclusion, proinflammatory conditions of sepsis repress mRNA coding ADAMTS13 and the ameliorating effect by selenite and APC may support the concept for identification of beneficial mechanisms triggered by these drugs at a molecular level. PMID:25860876

  16. Collagen VI microfibril formation is abolished by an {alpha}2(VI) von Willebrand factor type A domain mutation in a patient with Ullrich congenital muscular dystrophy.

    PubMed

    Tooley, Leona D; Zamurs, Laura K; Beecher, Nicola; Baker, Naomi L; Peat, Rachel A; Adams, Naomi E; Bateman, John F; North, Kathryn N; Baldock, Clair; Lamandé, Shireen R

    2010-10-22

    Collagen VI is an extracellular protein that most often contains the three genetically distinct polypeptide chains, α1(VI), α2(VI), and α3(VI), although three recently identified chains, α4(VI), α5(VI), and α6(VI), may replace α3(VI) in some situations. Each chain has a triple helix flanked by N- and C-terminal globular domains that share homology with the von Willebrand factor type A (VWA) domains. During biosynthesis, the three chains come together to form triple helical monomers, which then assemble into dimers and tetramers. Tetramers are secreted from the cell and align end-to-end to form microfibrils. The precise molecular mechanisms responsible for assembly are unclear. Mutations in the three collagen VI genes can disrupt collagen VI biosynthesis and matrix organization and are the cause of the inherited disorders Bethlem myopathy and Ullrich congenital muscular dystrophy. We have identified a Ullrich congenital muscular dystrophy patient with compound heterozygous mutations in α2(VI). The first mutation causes skipping of exon 24, and the mRNA is degraded by nonsense-mediated decay. The second mutation is a two-amino acid deletion in the C1 VWA domain. Recombinant C1 domains containing the deletion are insoluble and retained intracellularly, indicating that the mutation has detrimental effects on domain folding and structure. Despite this, mutant α2(VI) chains retain the ability to associate into monomers, dimers, and tetramers. However, we show that secreted mutant tetramers containing structurally abnormal C1 VWA domains are unable to associate further into microfibrils, directly demonstrating the critical importance of a correctly folded α2(VI) C1 domain in microfibril formation.

  17. Staphylococcus aureus protein A binding to von Willebrand factor A1 domain is mediated by conserved IgG binding regions.

    PubMed

    O'Seaghdha, Maghnus; van Schooten, Carina J; Kerrigan, Steven W; Emsley, Jonas; Silverman, Gregg J; Cox, Dermot; Lenting, Peter J; Foster, Timothy J

    2006-11-01

    Protein A (Spa) is a surface-associated protein of Staphylococcus aureus best known for its ability to bind to the Fc region of IgG. Spa also binds strongly to the Fab region of the immunoglobulins bearing V(H)3 heavy chains and to von Willebrand factor (vWF). Previous studies have suggested that the protein A-vWF interaction is important in S. aureus adherence to platelets under conditions of shear stress. We demonstrate that Spa expression is sufficient for adherence of bacteria to immobilized vWF under low fluid shear. The full length recombinant Ig-binding region of protein A, Spa-EDABC, fused to glutathione-S-transferase (GST), bound recombinant vWF in a dose-dependent and saturable fashion with half maximal binding of about 30 nm in immunosorbent assays. Full length-Spa did not bind recombinant vWF A3 domain but displayed binding to recombinant vWF domains A1 and D'-D3 (half maximal binding at 100 nm and 250 nm, respectively). Each recombinant protein A Ig-binding domain bound to the A1 domain in a similar manner to the full length-Spa molecule (half maximal binding 100 nm). Amino acid substitutions were introduced in the GST-SpaD protein at sites known to be involved in IgG Fc or in V(H)3 Fab binding. Mutants altered in residues that recognized IgG Fc but not those that recognized V(H)3 Fab had reduced binding to vWF A1 and D'-D3. This indicated that both vWF regions recognized a region on helices I and II that overlapped the IgG Fc binding site.

  18. Von Willebrand Factor Antigen Predicts Response to Double Dose of Aspirin and Clopidogrel by PFA-100 in Patients Undergoing Primary Angioplasty for St Elevation Myocardial Infarction

    PubMed Central

    Gianetti, Jacopo; Parri, Maria Serena; Della Pina, Francesca; Marchi, Federica; Koni, Endrin; De Caterina, Alberto; Maffei, Stefano

    2013-01-01

    Von Willebrand factor (VWF) is an emerging risk factor in acute coronary syndromes. Platelet Function Analyzer (PFA-100) with Collagen/Epinephrine (CEPI) is sensitive to functional alterations of VWF and also identifies patients with high on-treatment platelet reactivity (HPR). The objective of this study was to verify the effect of double dose (DD) of aspirin and clopidogrel on HPR detected by PFA-100 and its relation to VWF and to its regulatory metalloprotease ADAMTS-13. Between 2009 and 2011 we enrolled 116 consecutive patients with ST elevation myocardial infarction undergoing primary PCI with HPR at day 5 after PCI. Patients recruited were then randomized between a standard dose (SD, n = 58) or DD of aspirin and clopidogrel (DD, n = 58), maintained for 6 months follow-up. Blood samples for PFA-100, light transmittance aggregometry, and VWF/ADAMTS-13 analysis were collected after 5, 30, and 180 days (Times 0, 1, and 2). At Times 1 and 2 we observed a significantly higher CEPI closure times (CT) in DD as compared to SD (P < 0.001). Delta of CEPI-CT (T1 − T0) was significantly related to VWF (P < 0.001) and inversely related to ADAMTS-13 (0.01). Responders had a significantly higher level of VWF at T0. Finally, in a multivariate model analysis, VWF and ADAMTS-13 in resulted significant predictors of CEPI-CT response (P = 0.02). HRP detected by PFA-100 in acute myocardial infarction is reversible by DD of aspirin and clopidogrel; the response is predicted by basal levels of VWF and ADAMTS-13. PFA-100 may be a useful tool to risk stratification in acute coronary syndromes given its sensitivity to VWF. PMID:24453831

  19. Simplagrin, a Platelet Aggregation Inhibitor from Simulium nigrimanum Salivary Glands Specifically Binds to the Von Willebrand Factor Receptor in Collagen and Inhibits Carotid Thrombus Formation In Vivo

    PubMed Central

    Chagas, Andrezza C.; McPhie, Peter; San, Hong; Narum, David; Reiter, Karine; Tokomasu, Fuyuki; Brayner, Fabio A.; Alves, Luiz C.; Ribeiro, José M. C.; Calvo, Eric

    2014-01-01

    Background Among the several challenges faced by bloodsucking arthropods, the vertebrate hemostatic response against blood loss represents an important barrier to efficient blood feeding. Here we report the first inhibitor of collagen-induced platelet aggregation derived from the salivary glands of a black fly (Simulium nigrimanum), named Simplagrin. Methods and Findings Simplagrin was expressed in mammalian cells and purified by affinity-and size-exclusion chromatography. Light-scattering studies showed that Simplagrin has an elongated monomeric form with a hydrodynamic radius of 5.6 nm. Simplagrin binds to collagen (type I-VI) with high affinity (2–15 nM), and this interaction does not involve any significant conformational change as determined by circular dichroism spectroscopy. Simplagrin-collagen interaction is both entropically and enthalpically driven with a large negative ΔG, indicating that this interaction is favorable and occurs spontaneously. Simplagrin specifically inhibits von Willebrand factor interaction with collagen type III and completely blocks platelet adhesion to collagen under flow conditions at high shear rates; however, Simplagrin failed to block glycoprotein VI and Iα2β1 interaction to collagen. Simplagrin binds to RGQOGVMGF peptide with an affinity (KD 11 nM) similar to that of Simplagrin for collagen. Furthermore, Simplagrin prevents laser-induced carotid thrombus formation in vivo without significant bleeding in mice and could be useful as an antithrombotic agent in thrombosis related disease. Conclusion Our results support the orthology of the Aegyptin clade in bloodsucking Nematocera and the hypothesis of a faster evolutionary rate of salivary function of proteins from blood feeding arthropods. PMID:24921659

  20. Preserved Expression of mRNA Coding von Willebrand Factor-Cleaving Protease ADAMTS13 by Selenite and Activated Protein C.

    PubMed

    Ekaney, Michael L; Bockmeyer, Clemens L; Sossdorf, Maik; Reuken, Philipp A; Conradi, Florian; Schuerholz, Tobias; Blaess, Markus F; Friedman, Scott L; Lösche, Wolfgang; Bauer, Michael; Claus, Ralf A

    2015-04-03

    In sepsis, the severity-dependent decrease of von Willebrand factor (VWF)-inactivating protease, a disintegrin and metalloproteinase with thrombospondin motifs 13 (ADAMTS13), results in platelet aggregation and consumption, leading to sepsis-associated thrombotic microangiopathy (TMA) and organ failure. Previous reports assessing its functional deficiency have pinpointed involvement of autoantibodies or mutations to propagate thrombotic thrombocytopenic purpura (TTP). However, mechanisms of acquired ADAMTS13 deficiency during host response remain unclear. To enhance understanding of ADAMTS13 deficiency in sepsis, we evaluated changes in expression of mRNA coding ADAMTS13 during septic conditions using primary cellular sources of the protease. We hypothesized that proinflammatory cytokines and constituents of serum from septic patients affect the transcriptional level of ADAMTS13 in vitro, and previously recommended therapeutic agents as adjunctive therapy for sepsis interact therewith. Cultured hepatic stellate cells (HSCs), endothelial cells (HMEC) and human precision-cut liver slices as an ex vivo model were stimulated with sepsis prototypic cytokines, bacterial endotoxin and pooled serum obtained from septic patients. Stimulation resulted in a significant decrease in ADAMTS13 mRNA between 10% and 80% of basal transcriptional rates. Costimulation of selenite or recombinant activated protein C (APC) with serum prevented ADAMTS13 decrease in HSCs and increased ADAMTS13 transcripts in HMEC. In archived clinical samples, the activity of ADAMTS13 in septic patients treated with APC (n = 5) increased with an accompanying decrease in VWF propeptide as surrogate for improved endothelial function. In conclusion, proinflammatory conditions of sepsis repress mRNA coding ADAMTS13 and the ameliorating effect by selenite and APC may support the concept for identification of beneficial mechanisms triggered by these drugs at a molecular level.

  1. Protein replacement therapy and gene transfer in canine models of hemophilia A, hemophilia B, von willebrand disease, and factor VII deficiency.

    PubMed

    Nichols, Timothy C; Dillow, Aaron M; Franck, Helen W G; Merricks, Elizabeth P; Raymer, Robin A; Bellinger, Dwight A; Arruda, Valder R; High, Katherine A

    2009-01-01

    Dogs with hemophilia A, hemophilia B, von Willebrand disease (VWD), and factor VII deficiency faithfully recapitulate the severe bleeding phenotype that occurs in humans with these disorders. The first rational approach to diagnosing these bleeding disorders became possible with the development of reliable assays in the 1940s through research that used these dogs. For the next 60 years, treatment consisted of replacement of the associated missing or dysfunctional protein, first with plasma-derived products and subsequently with recombinant products. Research has consistently shown that replacement products that are safe and efficacious in these dogs prove to be safe and efficacious in humans. But these highly effective products require repeated administration and are limited in supply and expensive; in addition, plasma-derived products have transmitted bloodborne pathogens. Recombinant proteins have all but eliminated inadvertent transmission of bloodborne pathogens, but the other limitations persist. Thus, gene therapy is an attractive alternative strategy in these monogenic disorders and has been actively pursued since the early 1990s. To date, several modalities of gene transfer in canine hemophilia have proven to be safe, produced easily detectable levels of transgene products in plasma that have persisted for years in association with reduced bleeding, and correctly predicted the vector dose required in a human hemophilia B liver-based trial. Very recently, however, researchers have identified an immune response to adeno-associated viral gene transfer vector capsid proteins in a human liver-based trial that was not present in preclinical testing in rodents, dogs, or nonhuman primates. This article provides a review of the strengths and limitations of canine hemophilia, VWD, and factor VII deficiency models and of their historical and current role in the development of improved therapy for humans with these inherited bleeding disorders.

  2. Heparins that block VEGF-A-mediated von Willebrand factor fiber generation are potent inhibitors of hematogenous but not lymphatic metastasis

    PubMed Central

    Desch, Anna; Mayer, Frank Thomas; Koett, Julian; Nowak, Kai; Karampinis, Ioannis; Bohlmann, Michael K.; Umansky, Viktor; Bauer, Alexander Thomas

    2016-01-01

    Von Willebrand factor (VWF) serves as a nidus for platelet aggregation and thrombosis. We hypothesize that VWF fibers contribute to the development of venous thromboembolism (VTE) and to metastasis formation. Here, we show that vascular and lymphatic endothelial cells (ECs) express VWF in vitro and release VWF fibers after activation by tumor cell supernatants. In contrast, an ex vivo analysis of primary mouse tumors revealed the presence of VWF fibers in the blood microvasculature but not in lymphatic vessels. Unlike the anticoagulant Fondaparinux, an inhibitor of thrombin generation, the low-molecular-weight heparin (LMWH) Tinzaparin inhibited VWF fiber formation and vessel occlusion in tumor vessels by blocking thrombin-induced EC activation and vascular endothelial growth factor-A (VEGF-A)-mediated VWF release. Intradermal tumor cell inoculation in VWF- and ADAMTS13-deficient mice did not alter lymph node metastases compared with wild type animals. Interestingly, multiple tumor-free distal organs exhibited hallmarks of malignancy-related VTE, including luminal VWF fibers, platelet-rich thrombi and vessel occlusions. Furthermore, ADAMTS13 deficiency, characterized by prolonged intraluminal VWF network lifetimes, resulted in a severely increased number of metastatic foci in an experimental model of hematogenous lung seeding. Treatment with Tinzaparin inhibited tumor-induced release of VWF multimers, impeded platelet aggregation and decreased lung metastasis. Thus, our data strongly suggest a critical role of luminal VWF fibers in determining the occurrence of thrombosis and cancer metastasis. Moreover, the findings highlight LMWHs as therapeutic strategy to treat thrombotic complications while executing anti-metastatic activities. PMID:27602496

  3. Reassessment of ABO blood group, sex, and age on laboratory parameters used to diagnose von Willebrand disorder: potential influence on the diagnosis vs the potential association with risk of thrombosis.

    PubMed

    Favaloro, Emmanuel J; Soltani, Soma; McDonald, Jane; Grezchnik, Ella; Easton, Leanne; Favaloro, James W C

    2005-12-01

    We reassessed the influence of ABO blood group, sex, and age on plasma levels of von Willebrand factor (vWF) antigen, vWF:ristocetin cofactor, vWF:collagen binding assay, and factor VIII coagulant (FVIII:C). Data show that levels of vWF and FVIII:C increase with increasing age (P < .001 for all parameters) and that the ABO blood group influences plasma levels such that O group levels are significantly less than non-O group levels. There was no significant association with sex and Rh status. The selection of normal ranges based on ABO blood groups may influence the clinical diagnosis of von Willebrand disease (vWD) but might not be clinically relevant or help identify people at increased risk of bleeding. Differences in ABO-related ranges were more extensive at the high end of the ranges. This is of particular interest because high levels of vWF and FVIII are associated with thrombosis risk, and an ABO relationship also has been described. O group individuals may or may not be at greater risk for bleeding (they have lower levels of vWF and FVIII:C) and are more likely to be diagnosed with vWD. It also is possible that O group status may be protective for thrombosis.

  4. Laboratory testing for von Willebrand's disease: an assessment of current diagnostic practice and efficacy by means of a multi-laboratory survey. RCPA Quality Assurance Program (QAP) in Haematology Haemostasis Scientific Advisory Panel.

    PubMed

    Favaloro, E J; Smith, J; Petinos, P; Hertzberg, M; Koutts, J

    1999-10-01

    We report an evaluation of current laboratory practice for the diagnosis of von Willebrand's disease (VWD) by means of a multilaboratory survey. This assessment was undertaken with the RCPA Quality Assurance Program (QAP) in Haematology, which covers a wide geographic area encompassing Australia, New Zealand and Asia. A total of 25 laboratories actively involved in testing for VWD were selected to participate in a sample testing assessment exercise. Samples comprised 10 plasmas: (i) a normal plasma pool (in duplicate), (ii) this pool diluted to 50% (in duplicate), (iii) a normal individual (X1), (iv) severe Type 1 VWD (X1), (v) Type 2B VWD (x2 unrelated donors), (vi) Type 3 VWD (x1), (vii) Type 2A VWD (x1). Laboratories were asked to perform all tests available to them in order to establish a laboratory diagnosis of VWD, and then to comment on the possibility or otherwise of VWD. Overall findings indicated a wide variation in test practice, in the effectiveness of various test procedures in detecting VWD, and in the ability of various composite test panels to identify type 2 VWD subtypes. Firstly, while all laboratories (n = 25) performed tests for FVIII:C activity, von Willebrand factor 'antigen' (VWF:Ag) and a functional VWF assay [using the ristocetin cofactor assay (VWF:RCo; n = 23) and/or the collagen binding assay (VWF:CBA; n = 12)], only three laboratories carried out VWF:Multimer analysis. Secondly, for the three quantitative VWF assays, 10/25 (40%) laboratories performed all three, whereas 15/25 (60%) performed only two [VWF:Ag and VWF:RCo (n = 13); VWF:Ag and VWF:CBA (n = 2)]. Thirdly, a variety of assay methodologies were evident for VWF:Ag [ELISA, electro-immuno diffusion (EID), latex immuno-assay (LIA), and VIDAS assay] and VWF:RCo (platelet agglutination/'aggregometry' and a 'functional VWF:RCo-alternative' ELISA assay). Between method analysis for the quantitative VWF assays showed that the VWF:RCo yielded the greatest degree of inter

  5. Perioperative onset of acquired von Willebrand syndrome: Comparison between HVAD, HeartMate II and on-pump coronary bypass surgery

    PubMed Central

    Goetzenich, Andreas; Aljalloud, Ali; Woelke, Eva; Maas, Judith; Tewarie, Lachmandath; Schmitz-Rode, Thomas; Autschbach, Ruediger; Steinseifer, Ulrich; Moza, Ajay

    2017-01-01

    Objectives Acquired von Willebrand syndrome (AvWS) is associated with postoperative bleeding complications in patients with continuous flow left ventricular assist devices (CF-LVADs). The aim of this study is to analyze the perioperative vWF profile comparing an axial pump (HMII) to a centrifugal pump (HVAD) regarding the correlation between perioperative occurrence of AvWS, early- and late-postoperative bleeding events. Methods From July 2013 until March 2015 blood samples of 33 patients (12 HMII/ 8 HVAD/ 13 controls) were prospectively collected at 12 different time points and analyzed for the vWF antigen (vWF:Ag), its activity (vWF:Ac) and the vWF:Ac/vWF:Ag-ratio (vWF:ratio). The follow up period for postoperative bleeding events was from July 2013 until July 2016. Results Postoperatively, there was no difference in the vWF-profile between HVAD and HMII groups. However, a subgroup of patients already had significantly lower vWF:ratios preoperatively. Postoperatively, both CF-LVAD groups presented significantly lower vWF:ratios compared to the control group. Bleeding events per patient-year did not differ between the two groups (HMII vs. HVAD: 0.67 vs. 0.85, p = 0.685). We detected a correlation between vWF:ratio <0.7at LVAD-start (r = -0.583, p = 0.006) or at the end of surgery (r = -0.461, p = 0.035) and the occurrence of pericardial tamponade. In the control group, the drop in both vWF:Ag and vWF:Ac recovered immediately postoperatively above preoperative values. Conclusion A subgroup of patients with end-stage heart failure already suffers AvWS preoperatively. In both CF-LVAD groups, AvWS begins immediately after surgery. Intraoperative vWF:ratios <0.7 correlate with higher incidences of pericardial tamponade and re-operation. The presumably dilutive effect of the heart lung machine on vWF vanishes immediately at the end of surgery, possibly as part of an acute-phase response. PMID:28234916

  6. Influences of ABO blood group, age and gender on plasma coagulation factor VIII, fibrinogen, von Willebrand factor and ADAMTS13 levels in a Chinese population

    PubMed Central

    Wang, Zongkui; Dou, Miaomiao; Du, Xi; Ma, Li; Sun, Pan; Cao, Haijun; Ye, Shengliang; Jiang, Peng; Liu, Fengjuan; Lin, Fangzhao

    2017-01-01

    Background ABO blood group is a hereditary factor of plasma levels of coagulation factor VIII (FVIII) and von Willebrand factor (VWF). Age and gender have been shown to influence FVIII, VWF, fibrinogen (Fbg), and ADAMTS13 (A disintegrin and metalloprotease with thrombospondin type 1 motif, 13). We investigated the effects of ABO type, age, and gender on plasma levels of FVIII, Fbg, VWF, and ADAMTS13 in a Chinese population. Methods A total of 290 healthy volunteers were eligible for this study. ABO blood group was determined by indirect technique. FVIII:C and Fbg were measured by clotting assays. VWF antigen (VWF:Ag), collagen-binding activity (VWF:CBA), and ADAMTS13 antigen were assessed by ELISA, whereas VWF ristocetin cofactor activity (VWF:Rcof) was performed by agglutination of platelets with ristocetin. Results Mean FVIII:C and VWF levels (VWF:Ag, VWF:CBA, and VWF:Rcof) were significantly higher in non-O than in O type subjects (p < 0.05 for all comparison). ADAMTS13 antigen decreased with increasing age, whereas the other parameters increased. Other than ADAMTS13 (p < 0.01), no gender-related variations were observed in the other parameters. Moreover, FVIII:C, Fbg, VWF:Ag, VWF:CBA, and VWF:Rcof showed significant and positive relationships with age (r = 0.421, 0.445, 0.410, 0.401, and 0.589, resp.; all p < 0.001), whereas a negative relationship was observed for ADAMTS13 antigen (r = 0.306; p = 0.006). Furthermore, FVIII:C were strongly correlated with VWF:Ag, VWF:CBA, and VWF:Rcof (r = 0.746, r = 0.746, and r = 0.576, resp.; p < 0.0001). VWF parameters were also strongly correlated with each other (r = 0.0.847 for VWF:Ag and VWF:CBA; r = 0.722 for VWF:Ag and VWF:Rcof; p < 0.0001). Conclusions ABO blood group, age, and gender showed different effects on plasma levels of FVIII:C, Fbg, VWF:Ag, VWF:CBA, VWF:Rcof, and ADAMTS13 antigen. These new data on a Chinese population are quite helpful to compare with other ethnic groups. PMID

  7. The changes of von willebrand factor/a disintegrin-like and metalloprotease with thrombospondin type I repeats-13 balance in aneurysmal subarachnoid hemorrhage.

    PubMed

    Tang, Qi-Feng; Lu, Shi-Qi; Zhao, Yi-Ming; Qian, Jin-Xian

    2015-01-01

    The aim of this study was to investigate the role of Von Willebrand Factor/thrombospondin type I repeats-13 (VWF/ADAMTS13) balance in aSAH. Fifty eight patients with aSAH at the First Affiliated hospital of Soochow University, Suzhou, China, between January 2012 and January 2014 were eligible for the study. They were divided into delayed cerebral ischemia group (DCI group) and non-delayed cerebral ischemia group (no DCI group), or cerebral vasospasm group (CVS group) and no spasm group (no CVS group), or good outcome group and poor outcome group. The control group consisted of twenty healthy people. All patients underwent CT, DSA, or (and) CTA diagnosed with intracranial subarachnoid hemorrhage which is caused by aneurysm rupture. Venous blood was drawn in tubes at 3 time points: 1 day after SAH (T1), (4±1) days after SAH (T2), and (9±1) days after SAH (T3) to determine plasma concentrations of ADAMTS13, VWF, P-selectin and IL-6 via enzyme-linked immunosorbent assay (ELISA). Transcranial doppler sonography (TCD) was used to measure mean blood flow velocity of the middle cerebral artery (VMCA). Glasgow Outcome Scale (GOS) was measured before discharge. Among 58 patients, 12 (20.7%) had DCI, 40 (68.9%) had TCD evidence of CVS, and 20 (34.5%) had poor outcome. The concentrations of VWF, P-selectin and IL-6 on T1, T2 and T3 after SAH were significantly higher in DCI, CVS and poor outcome groups compared with those of the control group (P < 0.05). The concentrations of VWF, P-selectin and IL-6 were significantly higher in DCI, CVS and poor outcome groups compared with those of the no DCI, no CVS and good outcome groups. The activity of ADAMTS13 was lower in DCI and poor outcome groups compared with those of the no DCI and good outcome groups (P < 0.05). The activity of ADAMTS13 showed no difference in CVS group and no CVS group (P > 0.05). The results of our study suggest that the increased VWF and decreased ADAMTS13 activity were associated with DCI and poor outcome

  8. von Willebrand Disease (For Parents)

    MedlinePlus

    ... Lessons? Visit KidsHealth in the Classroom What Other Parents Are Reading Your Child's Development (Birth to 3 Years) Feeding Your 1- to 3- ... a genetic disorder that is usually passed from parent to child (very rarely, it can be acquired after birth). The child of a man or a woman ...

  9. Pharmacokinetics, efficacy, and safety of a plasma-derived VWF/FVIII concentrate (VONCENTO) for on-demand and prophylactic treatment in patients with von Willebrand disease (SWIFT-VWD study).

    PubMed

    Lissitchkov, Toshko J; Buevich, Evgeny; Kuliczkowski, Kazimierz; Stasyshyn, Oleksandra; Cerqueira, Monica Hermida; Klukowska, Anna; Joch, Christine; Seifert, Wilfried

    2017-03-01

    VONCENTO (CSL Behring Gmbh, Marburg, Germany) is a plasma-derived, high concentration, lower volume [relative to HAEMATE P (CSL Behring)], high-purity von Willebrand factor (VWF)/factor VIII (FVIII) concentrate with a VWF/FVIII ratio similar to HAEMATE P. This open-label, multicentre study investigated the pharmacokinetic, haemostatic efficacy, and safety profiles of VONCENTO in study participants at least 12 years of age with von Willebrand disease (VWD) who required treatment of nonsurgical bleeding (NSB) events or underwent surgery or prophylaxis. The first 12-month on-demand treatment period comprised a pharmacokinetic investigation and an efficacy analysis. After 12 months, qualifying study participants were switched to prophylactic therapy and included in a further 12-month efficacy analysis. In total, 21 study participants (including three adolescents, and 13 study participants with VWD type 3) received VONCENTO as on-demand treatment for 12 months. 'Excellent'/'good' haemostatic efficacy was achieved in 98.3% of the 407 NSB events assessed by investigators. Following the switch to prophylactic treatment, the total number of NSBs in eight patients markedly decreased from 304 to 10 (with haemostatic efficacy judged to be 'excellent' for all). The annualised bleeding rate also significantly decreased from a median of 26.5 events to one event. Safety assessments showed no inhibitory antibodies to either FVIII or VWF, no transmission of infectious agents, no thromboembolic events and no treatment-related serious adverse events. VONCENTO was shown to be well tolerated and provided excellent haemostatic efficacy in the treatment of bleeds or during prophylaxis in study participants with VWD, including also those with type 3, the severest form of VWD.

  10. Pharmacokinetics, efficacy, and safety of a plasma-derived VWF/FVIII concentrate (VONCENTO) for on-demand and prophylactic treatment in patients with von Willebrand disease (SWIFT-VWD study)

    PubMed Central

    Lissitchkov, Toshko J.; Buevich, Evgeny; Kuliczkowski, Kazimierz; Stasyshyn, Oleksandra; Cerqueira, Monica Hermida; Klukowska, Anna; Joch, Christine; Seifert, Wilfried

    2017-01-01

    VONCENTO (CSL Behring Gmbh, Marburg, Germany) is a plasma-derived, high concentration, lower volume [relative to HAEMATE P (CSL Behring)], high-purity von Willebrand factor (VWF)/factor VIII (FVIII) concentrate with a VWF/FVIII ratio similar to HAEMATE P. This open-label, multicentre study investigated the pharmacokinetic, haemostatic efficacy, and safety profiles of VONCENTO in study participants at least 12 years of age with von Willebrand disease (VWD) who required treatment of nonsurgical bleeding (NSB) events or underwent surgery or prophylaxis. The first 12-month on-demand treatment period comprised a pharmacokinetic investigation and an efficacy analysis. After 12 months, qualifying study participants were switched to prophylactic therapy and included in a further 12-month efficacy analysis. In total, 21 study participants (including three adolescents, and 13 study participants with VWD type 3) received VONCENTO as on-demand treatment for 12 months. ‘Excellent’/‘good’ haemostatic efficacy was achieved in 98.3% of the 407 NSB events assessed by investigators. Following the switch to prophylactic treatment, the total number of NSBs in eight patients markedly decreased from 304 to 10 (with haemostatic efficacy judged to be ‘excellent’ for all). The annualised bleeding rate also significantly decreased from a median of 26.5 events to one event. Safety assessments showed no inhibitory antibodies to either FVIII or VWF, no transmission of infectious agents, no thromboembolic events and no treatment-related serious adverse events. VONCENTO was shown to be well tolerated and provided excellent haemostatic efficacy in the treatment of bleeds or during prophylaxis in study participants with VWD, including also those with type 3, the severest form of VWD. PMID:27203734

  11. Further characterization of the thrombasthenia-related idiotype OG. Antiidiotype defines a novel epitope(s) shared by fibrinogen B beta chain, vitronectin, and von Willebrand factor and required for binding to beta 3

    PubMed Central

    1994-01-01

    A patient (OG) with Glanzmann thrombasthenia became refractory to platelet transfusion after the production of an immunoglobulin G (IgG) isoantibody (Ab1) specific for the integrin subunit beta 3. To determine the frequency at which the OG idiotype is found in the general population and in immune-mediated disease states, we developed a rabbit polyclonal antibody (Ab2) specific for affinity-purified OG anti-beta 3 Fab. The binding of Ab2 to Ab1 is inhibited by purified alpha IIb beta 3. Ab2 als binds to IgG specific for alpha IIb beta 3 obtained from one nonrelated Glanzmann thrombasthenia patient ES who has developed isoantibodies of similar specificity. On the other hand, Ab2 does not recognize alpha IIb beta 3-specific antibodies produced by two Glanzmann thrombasthenia patients, AF and LUC, who have developed isoantibodies with specificities distinct from that of the OG isoantibody. Moreover, Ab2 does not recognize alpha IIb beta 3-specific antibodies developed by three representative patients with (autoimmune) thrombocytopenic purpura or six representative patients with alloimmune thrombocytopenias, nor does it bind to IgG from any of 13 nonimmunized individuals. We have found that Ab2 also binds to selected protein ligands of alpha IIb beta 3 namely, fibrinogen, vitronectin, and von Willebrand factor, but not to other protein ligands or control proteins, such a fibronectin, type I collagen, and albumin. The epitope(s) recognized by Ab2 on each adhesive protein are either very similar or identical since each protein can inhibit the binding of Ab2 to any of the other proteins. The epitope on fibrinogen recognized by Ab2 resides in the B beta chain, and is likely contained within the first 42 amino acids from the NH2 terminus. Since OG IgG inhibits fibrinogen binding to alpha IIb beta 3, the specificity of the OG idiotype defines a novel binding motif for the integrin alpha IIb beta 3 that is shared by fibrinogen, vitronectin, and von Willebrand factor, but

  12. Single automated donor plateletpheresis increases the plasma level of proinflammatory cytokine tumor necrosis factor-alpha which does not associate with endothelial release markers von Willebrand factor and fibronectin.

    PubMed

    Karadoğan, I; Ozdoğan, M; Undar, L

    2000-12-01

    The effect of plateletpheresis on endothelium, which has strong effects on blood coagulation, fibrinolysis and platelet function, is not known. Activation of leukocytes and subsequent generation of proinflammatory cytokines during the extracorporeal circulation may activate the endothelium. To test this hypothesis we measured plasma levels of tumor necrosis factor (TNF)-alpha as a prototype of the proinflammatory cytokines, and von Willebrand factor (vWF) and fibronectin as endothelial release/damage markers before and after a single plateletpheresis procedure on an intermittent-flow machine Haemonetics MCS 3p in 17 healthy donors. We found a significant increase in median plasma level of TNF-alpha following plateletpheresis (3.5 vs 26.5 pg/ml, P=0.02). Such increases in vWF and fibronectin were not observed. The increase in plasma TNF-alpha indicates that a single plateletpheresis procedure causes leukocyte activation which does not seemingly impair endothelial cell function. The relation of plateletpheresis-induced proinflammatory cytokine release to some adverse effects observed in both donors and recipients, and the effect of repeated plateletpheresis on endothelium deserve further studies.

  13. High-Affinity DNA Aptamer Generation Targeting von Willebrand Factor A1-Domain by Genetic Alphabet Expansion for Systematic Evolution of Ligands by Exponential Enrichment Using Two Types of Libraries Composed of Five Different Bases.

    PubMed

    Matsunaga, Ken-Ichiro; Kimoto, Michiko; Hirao, Ichiro

    2017-01-11

    The novel evolutionary engineering method ExSELEX (genetic alphabet expansion for systematic evolution of ligands by exponential enrichment) provides high-affinity DNA aptamers that specifically bind to target molecules, by introducing an artificial hydrophobic base analogue as a fifth component into DNA aptamers. Here, we present a newer version of ExSELEX, using a library with completely randomized sequences consisting of five components: four natural bases and one unnatural hydrophobic base, 7-(2-thienyl)imidazo[4,5-b]pyridine (Ds). In contrast to the limited number of Ds-containing sequence combinations in our previous library, the increased complexity of the new randomized library could improve the success rates of high-affinity aptamer generation. To this end, we developed a sequencing method for each clone in the enriched library after several rounds of selection. Using the improved library, we generated a Ds-containing DNA aptamer targeting von Willebrand factor A1-domain (vWF) with significantly higher affinity (KD = 75 pM), relative to those generated by the initial version of ExSELEX, as well as that of the known DNA aptamer consisting of only the natural bases. In addition, the Ds-containing DNA aptamer was stabilized by introducing a mini-hairpin DNA resistant to nucleases, without any loss of affinity (KD = 61 pM). This new version is expected to consistently produce high-affinity DNA aptamers.

  14. Consumption of nattokinase is associated with reduced blood pressure and von Willebrand factor, a cardiovascular risk marker: results from a randomized, double-blind, placebo-controlled, multicenter North American clinical trial

    PubMed Central

    Jensen, Gitte S; Lenninger, Miki; Ero, Michael P; Benson, Kathleen F

    2016-01-01

    Objective The objective of this study is to evaluate the effects of consumption of nattokinase on hypertension in a North American hypertensive population with associated genetic, dietary, and lifestyle factors. This is in extension of, and contrast to, previous studies on Asian populations. Materials and methods A randomized, double-blind, placebo-controlled, parallel-arm clinical study was performed to evaluate nattokinase (NSK-SD), a fermented soy extract nattō from which vitamin K2 has been removed. Based on the results from previous studies on Asian populations, 79 subjects were enrolled upon screening for elevated blood pressure (BP; systolic BP ≥130 or diastolic BP ≥90 mmHg) who consumed placebo or 100 mg nattokinase/d for the 8-week study duration. Blood collections were performed at baseline and 8 weeks for testing plasma renin activity, von Willebrand factor (vWF), and platelet factor-4. Seventy-four people completed the study with good compliance. Results Consumption of nattokinase was associated with a reduction in both systolic and diastolic BP. The reduction in systolic BP was seen for both sexes but was more robust in males consuming nattokinase. The average reduction in diastolic BP in the nattokinase group from 87 mmHg to 84 mmHg was statistically significant when compared to that in the group consuming placebo, where the average diastolic BP remained constant at 87 mmHg (P<0.05), and reached a high level of significance for males consuming nattokinase, where the average diastolic BP dropped from 86 mmHg to 81 mmHg (P<0.006). A decrease in vWF was seen in the female population consuming nattokinase (P<0.1). In the subpopulation with low plasma renin activity levels at baseline (<0.29 ng/mL/h), an increase was seen for 66% of the people after 8-week consumption of nattokinase (P<0.1), in contrast to only 8% in the placebo group. Conclusion The data suggest that nattokinase consumption in a North American population is associated with beneficial

  15. How Is von Willebrand Disease Treated?

    MedlinePlus

    ... children, endometrial ablation (EN-do-ME-tre-al ab-LA-shun) is done. This procedure destroys the lining of the uterus. It has been shown to reduce menstrual blood loss in women who have VWD. If you ...

  16. Genetics Home Reference: von Willebrand disease

    MedlinePlus

    ... PubMed Nichols WL, Hultin MB, James AH, Manco-Johnson MJ, Montgomery RR, Ortel TL, Rick ME, Sadler ... JE, Yawn BP, James AH, Hultin MB, Manco-Johnson MJ, Weinstein M. Clinical and laboratory diagnosis of ...

  17. Prophylaxis of bleeding episodes in patients with von Willebrand’s disease

    PubMed Central

    Federici, Augusto B.

    2008-01-01

    Patients with severe forms of von Willebrand’s disease (VWD) may have frequent haemarthroses, especially when factor VIII (FVIII) levels are below 10 U/dL, so that some of them develop target joints like patients with severe haemophilia A. Some patients have recurrent gastrointestinal bleeding, often without lesions in the gastrointestinal tract, and need treatment every day or every other day. Finally, there are children who have epistaxis frequently and severely enough to cause anaemia. In these frequent and severe bleeders, the optimal therapy may be secondary long-term prophylaxis with von Willebrand factor (VWF)/FVIII concentrates rather than on-demand treatment on the occasion of bleeding episodes. The largest experience on such prophylaxis in VWD has been in Sweden in 35 patients with severe forms of VWD. Long-term prophylaxis was also implemented in a cohort of Italian patients with VWD: prophylaxis was used in seven patients with types 3 (n=1), 2A (n=4), 2M (n=1) and type 1 (n=1) VWD because of recurrent gastrointestinal bleeds and in four patients with type 3 VWD because of joint bleeds. Prophylaxis prevented bleeding completely in eight patients and largely reduced hospitalisation for blood transfusions in the remaining three. The cost-effectiveness of these prophylaxis regimens versus on-demand therapy will now be investigated in one large international study. PMID:19105507

  18. Characterization of the von Willebrand factor (vWD) gene in von Willebrand disease (vWD) type III patients from 24 families of Swedish and Finnish origin

    SciTech Connect

    Zhang, Z.P.; Blombaeck, M.; Anvret, M.

    1994-09-01

    Twenty-four patients with vWD type III were screened for mutations in the vWF gene using the PCR technique followed by direct sequencing. More than 250 kilobases (kb) of genomic DNA were sequenced, including the promoter and coding region (52 exons) of the vWF gene from 24 patients. Altogether 14 mutations were detected: a thymidine insertion in exon 14, a 20 bp deletion in exon 15, a single cytosine deletion in exon 18, a cytosine insertion in exon 28, the nonsense mutations in exons 15, 16, 28, 32 and 45, a mutation in donor splice site of exon 43 and four candidate mutations in exons 5, 18, 28, 49 and 51. Forty-two mutant alleles were identified (42/48); 11 probands are homozygous for the mutations and 8 are compound heterozygous. In addition, a new subfamily of the Alu sequence in the promoter region and 10 new polymorphisms were identified. Our studies indicate that most of the vWD type III patients have homozygous or compound heterozygous mutations in the vWF gene. The vWD type I patients do in some cases have two different mutant alleles of the vWF gene. The two mutant vWF proteins may compensate each other so that the synthesis of the vWF protein will be not seriously disrupted.

  19. Modification of the platelet binding domain of von Willebrand Factor (vWF)

    SciTech Connect

    Silverman, C.; Mascelli, M.A.; Karl, D.W.; Kirby, E.P.

    1986-05-01

    Bovine vWF has been modified with /sup 125/I-Bolton Hunter reagent (I/sup */-BHR) with a concomittant loss of its platelet agglutinating activity and a reduction in its ability to bind to platelets. BHR labels free alpha and epsilon amino groups. The I/sup */-BHR-vWF migrated as a single band of M/sub r/ = 210kD on reduced SDS polyacrylamide gels. Its multimeric composition on SDS agarose gels was identical to unlabeled vWF. Incorporation of an average of 1.2 moles of I/sup */-BHR/subunit vWF at pH 8.5 caused a 50% loss of platelet agglutinating activity. This represents less than 2% of the 118 lysine residues in each subunit vWF. No I/sup */-BHR was released after treatment with 1M hydroxylamine which would cleave O-acylated tyrosines. Digestion of both unlabeled and I/sup */-BHR-vWF with Protease 1, a metalloprotease from the venom of western diamondback rattlesnake, produces two fragments which have an M/sub r/ of 250kD and 200kD. The 250kD fragment contains the platelet binding site and is composed of 3 peptide chains with M/sub r/ 125kD, 78kD and 45kD. Gels of the 250kD fragment from I/sup */-BHR-vWF revealed radioactivity predominantly in the 125kD fragment, suggesting that the platelet binding site resides on the 125kD fragment.

  20. Theodore von Karman

    NASA Technical Reports Server (NTRS)

    1926-01-01

    Theodore von Karman. NACA: In the eyes of most aeronautical experts, the overall record of Max Munk in aerodynamic research falls short of that achieved by fellow immigrant Theodore von Karman (the short man in the double breasted coat in the middle), shown here visiting Langley in December 1926. People in the photo include Max Munk, aerodynamic researcher; Theodore von Karman; George Lewis, director of research; Henry Reid, engineer in charge; Fred Weick, PRT head; Paul Hemke; Elliott Reid, future Stanford University Professor.

  1. Dr. Wernher Von Braun

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Dr. Wernher Von Braun (left) and Fred W. Kelley examine a ST-100 Stellar Instrument Platform in the astrionics lab. Dr. Von Braun, then deputy associate administrator for planning, NASA, was visiting on the anniversary of the establishment of the Marshall Space Flight Center.

  2. Dr. Wernher von Braun

    NASA Technical Reports Server (NTRS)

    2004-01-01

    Dr. von Braun is looking out from a 10th floor window of building 4200 at the Marshall Space Flight Center (MSFC). He was the first Center Director and served as the Director from July 1960 through February 1970. Following World War II, Dr. von Braun and his German colleagues arrived in the United States under the Project Paperclip (American acquisition of German rocket experts) to continue their rocket development work. In 1950, von Braun and his German Rocket Team (also called the Peenemuende Team) were transferred from Ft. Bliss, Texas to Huntsville, Alabama to work for the Army's rocket program at Redstone Arsenal and later, NASA's Marshall Space Flight Center (MSFC). Under Dr. von Braun's leadership, MSFC developed the Saturn V launch vehicle, which placed the first men, two American astronauts, on the Moon. Wernher von Braun's life was dedicated to expanding man's knowledge through the exploration of space.

  3. Dr. Wernher Von Braun

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Dr. Wernher Von Braun (right), Deputy Associate Administrator for planning, National Aeronautics and Space Administration, inspects the mockup of the Saturn Workshop during a visit marking the 10th anniversary of the Marshall Center. Shown with Dr. Von Braun, from left to right, are Karl Heimburg, Director of the astronautics lab; Herman K. Weidner, Director of Science and Engineering, and George Hardy of the Astronautics lab.

  4. Dr. Wernher Von Braun

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Dr. Wernher Von Braun (right), Deputy Associate Administrator for Planning, National Aeronautics and Space Administration, inspects the mockup of the Saturn Workshop during a visit marking the 10th anniversary of the Marshall Center. Shown with Dr. Von Braun, from left to right, are Karl Heimburg, Director of the Astronautics Lab; Herman K. Weidner, Director of Science and Engineering, and George Hardy of the Astronautics Lab.

  5. Energetische Verwertung von Biomasse

    NASA Astrophysics Data System (ADS)

    Zahoransky, Richard; Allelein, Hans-Josef; Bollin, Elmar; Oehler, Helmut; Schelling, Udo

    Etwa 0,1% der Solarenergie wandeln sich durch Photosynthese aus dem Kohlendioxid der Luft in Biomasse um. Die Biomassen sind als Festbrennstoff nutzbar oder zu gasförmigen Brennstoffen weiterverarbeitbar. Zwei Arten von Biomassen sind zu unterscheiden: Anfallende Biomasse

  6. Dr. Wernher Von Braun

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Shown viewing the Apollo telescope mockup are, from left to right, Charles Donlan, deputy associate administrator for manned space flight; Dr. Wernher Von Braun, Marshall Space Flight Center director; William Horton, astrionics lab; Dr. Thomas Paine, NASA deputy administrator; Warner Kuers, director of the ME lab.

  7. Tetraglyme Coatings Reduce Fibrinogen and von Willebrand Factor Adsorption and Platelet Adhesion under Both Static and Flow Conditions

    PubMed Central

    Zhang, Min; Horbett, Thomas A.

    2013-01-01

    Previous studies have showed that radio-frequency plasma deposited tetraglyme coatings greatly reduced fibrinogen adsorption (ΓFg) from highly diluted plasmas (0.1% and 1%) and subsequent platelet adhesion under static conditions. In this study, the protein resistant properties of tetraglyme were re-examined with high-concentration plasma, and subsequent platelet adhesion was measured under both static and flow conditions. The resistance of tetraglyme to vWf adsorption (ΓvWf) and the role of vWf in platelet adhesion under flow were also investigated. ΓFg and ΓvWf were measured with 125I radiolabeled proteins. Flow studies were done at shear rates of 50 or 500 s−1 by passing a platelet/red cell suspension through a GlycoTech flow chamber. When adsorbed from a series of increasing plasma concentrations, the adsorption of both proteins to tetraglyme increased steadily, and did not show a peak at intermediate dilutions, i.e. there was no Vroman effect. When plasma concentration was less than 10%, the tetraglyme surface was highly non-fouling, exhibiting ultralow ΓFg (less than 5 ng/ cm2) and extremely low platelet adhesion under both static and flow conditions. However, when the adsorption was done from 100% plasma, ΓFg was much higher (~ 85 ng/cm2), indicating that tetraglyme surface may not be sufficiently protein-resistant in the physiological environment. To correlate platelet adhesion under flow with ΓFg and ΓvWf, a series of tetraglyme surfaces varying in ether content and protein adsorption was created by varying deposition power. On these surfaces, platelet adhesion at low shear rate depended only on the amount of ΓFg, but under high shear, both ΓFg and ΓvWf affected platelet adhesion. In particular, it was found that ΓvWf must be reduced to less than 0.4 ng/cm2 to achieve ultra low platelet adhesion under high shear. PMID:18496865

  8. Von Karman swirling flows

    NASA Astrophysics Data System (ADS)

    Zandbergen, P. J.; Dijkstra, D.

    A development history is presented for research on the problem of swirling flow infinite disks from its formulation by von Karman in 1921 through the treatments of Batchelor (1951) and Stewartson (1953) to the present, with a view to both its one-disk and two-disk forms. Attention is given to the stability of the stationary solutions for these problems, and to the case where the radii of the disks are finite. The question as to the extent to which the Karman swirling flow occurs in a finite radial geometry is noted to be of fundamental importance.

  9. Dr. Wernher Von Braun

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Dr. Thomas Paine, Deputy Administrator of the National Aeronautics and Space Administration, examines an ordinary man's shoe outfitted for use in the Saturn I workshop. Pictured from the left in the Saturn I workshop mockup are William Brooksbank, propulsion and vehicle engineering laboratory; Dr. Paine; Dr. Wernher Von Braun, Marshall Center director; Colonel Clare F. Farley, Executive Officer in the Office Of The Administrator; and Charles J. Donlan, Deputy Associate Administrator for Manned Space Flight, Technical. the shoe Dr. Paine is holding has a unique fastener built into the sole to allow an astronaut to move about on the workshop floor and to remain in one position if he desires.

  10. John von Neumann Birthday Centennial

    SciTech Connect

    Grcar, Joseph F.

    2004-11-12

    In celebration of John von Neumann's 100th birthday, a series of four lectures were presented on the evening of February 10, 2003 during the SIAM Conference on Computational Science and Engineering in San Diego. The venue was appropriate because von Neumann spent much of the later part of his life, in the 1950's, as an unofficial ambassador for computational science. He was then the only senior American scientist who had experience with the new computers (digital, electronic, and programmable) and a vision of their future importance. No doubt he would have relished the chance to attend a meeting such as this. The first speaker, William Aspray, described the ''interesting times'' during which computers were invented. His remarks were based on his history [1] of this period in von Neumann's life. We were honored to have John von Neumann's daughter, Marina von Neumann-Whitman, as our second speaker. Other accounts of von Neumann's life can be found in books by two of his colleagues [2] and [3]. Our third speaker, Peter Lax, provided both mathematical and international perspectives on John von Neumann's career. Finally, Pete Stewart spoke about von Neumann's numerical error analysis [4] in the context of later work; this talk did not lend itself to transcription, but readers may consult the historical notes in [5]. Our thanks to all the speakers for a remarkable evening. We are grateful to the DOE Applied Mathematical Sciences (AMS) program for partially supporting these lectures. Thanks are also due to SIAM and William Kolata, to our emcee, Gene Golub, to Paul Saylor for recording and editing, and to Barbara Lytle for the transcriptions. More about von Neumann's work can be learned from the recent American Mathematical Society proceedings [6].

  11. von Karman Vortices

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Each of these swirling clouds is the result of a meteorological phenomenon known as a von Karman vortex. These vortices appeared over Alexander Selkirk Island in the southern Pacific Ocean. Rising precipitously from the surrounding waters, the island's highest point is nearly a mile (1.6 km) above sea level. As wind-driven clouds encounter this obstacle, they flow around it to form large, spinning eddies. This image was acquired by Landsat 7's Enhanced Thematic Mapper plus (ETM+) sensor on September 15, 1999. This is a false-color composite image made using shortwave infrared, infrared, and near-infrared wavelengths. Image provided by the USGS EROS Data Center Satellite Systems Branch.

  12. Von Hippel's disease in association with von Recklinghausen's neurofibromatosis.

    PubMed Central

    Thomas, J V; Schwartz, P L; Gragoudas, E S

    1978-01-01

    Ten members of a large family who showed manifestations of either von Hippel-Lindau disease or von Recklinghausen's neurofibromatosis were examined. Three of 10 members were found to have retinal angiomas which had not been present on fundus examination 3 years previously. These angiomas were associated with ocular and systemic signs of neurofibromatosis. These cases show overlapping manifestations of different phakomatoses and provide support for the concept of a common aetiology for these diseases. Images PMID:101230

  13. von Braun and German Publisher

    NASA Technical Reports Server (NTRS)

    1969-01-01

    In this photograph, Guenter Ogger of Capitol Magazine, West Germany, greets Marshall Space Flight Center Director, Dr. Wernher von Braun. Mr. Ogger interviewed the famous rocket scientist for his magazine.

  14. Von Karman and JATO Team

    NASA Technical Reports Server (NTRS)

    1940-01-01

    Dr. Theodore von Karman (black coat) sketches out a plan on the wing of an airplane as his JATO engineering team looks on. From left to right: Dr. Clark B. Millikan, Dr.Martin Summerfield, Dr. Theodore von Karman, Dr. Frank J. Malina and pilot, Capt. Homer Boushey. Captain Boushey would become the first American to pilot an airplane that used JATO (Jet Assisted Take-Off) solid propellent rockets.

  15. Richard von Volkmann

    PubMed Central

    Willy, Christian; Schneider, Peter; Engelhardt, Michael; Hargens, Alan R.

    2008-01-01

    Richard von Volkmann (1830–1889), one of the most important surgeons of the 19th century, is regarded as one of the fathers of orthopaedic surgery. He was a contemporary of Langenbeck, Esmarch, Lister, Billroth, Kocher, and Trendelenburg. He was head of the Department of Surgery at the University of Halle, Germany (1867–1889). His popularity attracted doctors and patients from all over the world. He was the lead physician for the German military during two wars. From this experience, he compared the mortality of civilian and war injuries and investigated the general poor hygienic conditions in civilian hospitals. This led him to introduce the “antiseptic technique” to Germany that was developed by Lister. His powers of observation and creativity led him to findings and achievements that to this day bear his name: Volkmann’s contracture and the Hueter-Volkmann law. Additionally, he was a gifted writer; he published not only scientific literature but also books of children’s fairy tales and poems under the pen name of Richard Leander, assuring him a permanent place in the world of literature as well as orthopaedics. PMID:18196438

  16. Von Hippel-Lindau Disease

    MedlinePlus

    Von Hippel-Lindau disease (VHL) is a rare, genetic disease that causes tumors and cysts to grow in your body. The tumors can be either ... and, in men, their genital tract. Symptoms of VHL vary and depend on the size and location ...

  17. [Was Klaus von Mantrei the teacher of Hans von Gersdorff?].

    PubMed

    Vollmuth, R

    1996-01-01

    One of the most popular representatives of surgery at the end of the middle ages and the beginning modern era is the Strassburgian surgeon Hans von Gersdorff. Still we do not know very much about his life and his surgical teachers. Only one meister Nicklaus, called Mulartzt, is mentioned as such by the remarks in Gersdorffs 'Feldbuch der Wundarznei', but till today this surgeon could not be identified in more detail. This article now holds the thesis, that meister Nicklaus is probably identical with Klaus von Matrei (Metry), a well-known surgeon of the late 15th century. That cannot be fully proved yet, but a number of coinciding characteristics between the two and some further indications, that are explained, seem so significant, that the thesis can hardly be doubted.

  18. Dr. von Braun Briefing Walt Disney

    NASA Technical Reports Server (NTRS)

    1965-01-01

    Dr. von Braun began his association with Walt Disney in the 1950s when the rocket scientist appeared in three Disney television productions related to the exploration of space. Years later, Dr. von Braun invited Disney and his associates to tour the Marshall Space Flight Center (MSFC) in Huntsville, Alabama. This photograph is dated April 13, 1965. From left are R.J. Schwinghamer from the MSFC, Disney, B.J. Bernight, and Dr. von Braun.

  19. Nichtlineare Rauschmodellierung von LC Tank VCOs

    NASA Astrophysics Data System (ADS)

    Thiessen, T.; Bremer, J.-K.; Mathis, W.

    2008-05-01

    Im Rahmen dieser Arbeit wird ein alternativer Ansatz zur Phasenrauschoptimierung von LC-Tank Oszillatoren (VCOs) unter Verwendung stochastischer Differentialgleichungen vorgestellt. Zunächst werden die linearen Ansätze von Leeson, Hajimiri und Lee analysiert und bewertet. Danach wird ein Konzept vorgestellt, mit dem man die Rauscheigenschaften von VCOs auf der Grundlage stochastischer Differentialgleichungen und Fokker-Planck-Gleichungen untersuchen kann. Ziel dieser Arbeit ist eine Beschreibung des Phasenrauschens auf der Basis einer nichtlinearen Rauschmodellierung, welche Parameter eines VCOs für eine Optimierung beinhaltet. Es wurde ein Matlab-Tool erstellt und die Funktionalität anhand von Simulationen verifiziert.

  20. Reflexionseigenschaften von Windenergieanlagen im Funkfeld von Funknavigations- und Radarsystemen

    NASA Astrophysics Data System (ADS)

    Sandmann, S.; Divanbeigi, S.; Garbe, H.

    2015-11-01

    Die hier behandelte Untersuchung befasst sich mit den Störungen des elektrischen Feldes einer Doppler Very High Frequency Omnidirectional Radio Range Navigationsanlage (DVOR) in der Gegenwart von Windenergieanlagen (WEA). Hierfür wird die Feldstärke auf 25 konzentrischen Kreisbahnen, sog. Orbit Flights verschiedener Höhen und mit verschiedenen Radien rund um die DVOR-Anlage numerisch simuliert. Insbesondere werden die Einflüsse diverser Parameter der WEA wie deren Anzahl, Position, Rotorwinkel, Turmhöhe und Rotordurchmesser auf die Feldverteilung herausgestellt, sowie die Anwendbarkeit der Simulationsmethode Physical Optics (PO) durch Vergleich der Simulationsergebnisse mit denen der Multi Level Fast Multipol Method (MLFMM) untersucht.

  1. Dr. Wernher Von Braun at a picnic.

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Dr. Wernher Von Braun, director of the Marshall Space Flight Center, stakes claim to a table for the picnic celebrating man's first lunar landing. With Dr. Von Braun are his wife, Maria (seated, right), and son, Peter (back to camera). His daughter, Margrit, was also present, but is hidden from view by friends in this view.

  2. Dr. Wernher Von Braun greeting dignitaries.

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Dr. Wernher Von Braun, left, greets vice president Spiro T. Agnew in the Launch Control Center for the Apollo 14 mission. Between Dr. Von Braun and Mr. Agnew are their Royal Highnesses, The Prince and Princess of Spain. The royal visitors greeted the launch control team in th enter after the launch of Apollo 14.

  3. Dr. von Braun Tries Out the NBS

    NASA Technical Reports Server (NTRS)

    1967-01-01

    Marshall Space Flight Center (MSFC) Director, Dr. von Braun, is shown fitted with suit and diving equipment as he prepares for a tryout in the MSFC Neutral Buoyancy Simulator (NBS). Weighted to a neutrally buoyant condition, Dr. von Braun was able to perform tasks underwater which simulated weightless conditions found in space.

  4. Walt Disney and Dr. Wernher von Braun

    NASA Technical Reports Server (NTRS)

    1954-01-01

    Dr. Werhner von Braun, then Chief, Guided Missile Development Operation Division at Army Ballistic Missile Agency (ABMA) in Redstone Arsenal, Alabama, was visited by Walt Disney in 1954. In the 1950's, von Braun worked with Disney Studio as a technical director, making three films about space exploration for television. A model of the V-2 rocket is in background.

  5. Dr. Wernher von Braun Laid to Rest

    NASA Technical Reports Server (NTRS)

    1977-01-01

    Dr. Wernher von Braun served as Marshall Space Flight Center's first director from July 1, 1960 until January 27, 1970, when he was appointed NASA Deputy Associate Administrator for Planning. Following World War II, Dr. von Braun and his German colleagues arrived in the United States under Project Paper Clip to continue their rocket development work. In 1950, von Braun and his rocket team were transferred from Ft. Bliss, Texas to Huntsville, Alabama to work for the Army's rocket program at Redstone Arsenal and later, NASA's Marshall Space Flight Center. Under von Braun's leadership, Marshall developed the Saturn V launch vehicle which took Apollo astronauts to the moon. Dr. von Braun died in Alexandria, Va., on June 16, 1977, seven years after his NASA appointment. This photo was taken at the site where he was laid to rest.

  6. Dr. Wernher von Braun In His Office

    NASA Technical Reports Server (NTRS)

    1964-01-01

    Dr. Wernher von Braun served as Marshall Space Flight Center's first director from July 1, 1960 until January 27, 1970, when he was appointed NASA Deputy Associate Administrator for Planning. Following World War II, Dr. von Braun and his German colleagues arrived in the United States under Project Paperclip to continue their rocket development work. In 1950, von Braun and his rocket team were transferred from Ft. Bliss, Texas to Huntsville, Alabama to work for the Army's rocket program at Redstone Arsenal and later, NASA's Marshall Space Flight Center. Under von Braun's leadership, Marshall developed the Saturn V launch vehicle which took Apollo astronauts to the moon. This photo depicts von Braun in his office at MSFC.

  7. A factor VIII-derived peptide enables von Willebrand factor (VWF)-binding of artificial platelet nanoconstructs without interfering with VWF-adhesion of natural platelets

    NASA Astrophysics Data System (ADS)

    Haji-Valizadeh, Hassan; Modery-Pawlowski, Christa L.; Sen Gupta, Anirban

    2014-04-01

    There is substantial clinical interest in synthetic platelet analogs for potential application in transfusion medicine. To this end, our research is focused on self-assembled peptide-lipid nanoconstructs that can undergo injury site-selective adhesion and subsequently promote site-directed active platelet aggregation, thus mimicking platelet's primary hemostatic actions. For injury site-selective adhesion, we have utilized a coagulation factor FVIII-derived VWF-binding peptide (VBP). FVIII binds to VWF's D'-D3 domain while natural platelet GPIbα binds to VWF's A1 domain. Therefore, we hypothesized that the VBP-decorated nanoconstructs will adhere to VWF without mutual competition with natural platelets. We further hypothesized that the adherent VBP-decorated constructs can enhance platelet aggregation when co-decorated with a fibrinogen-mimetic peptide (FMP). To test these hypotheses, we used glycocalicin to selectively block VWF's A1 domain and, using fluorescence microscopy, studied the binding of fluorescently labeled VBP-decorated nanoconstructs versus platelets to ristocetin-treated VWF. Subsequently, we co-decorated the nanoconstructs with VBP and FMP and incubated them with human platelets to study construct-mediated enhancement of platelet aggregation. Decoration with VBP resulted in substantial construct adhesion to ristocetin-treated VWF even if the A1-domain was blocked by glycocalicin. In comparison, such A1-blocking resulted in significant reduction of platelet adhesion. Without A1-blocking, the VBP-decorated constructs and natural platelets could adhere to VWF concomitantly. Furthermore, the constructs co-decorated with VBP and FMP enhanced active platelet aggregation. The results indicate significant promise in utilizing the FVIII-derived VBP in developing synthetic platelet analogs that do not interfere with VWF-binding of natural platelets but allow site-directed enhancement of platelet aggregation when combined with FMP.There is substantial clinical interest in synthetic platelet analogs for potential application in transfusion medicine. To this end, our research is focused on self-assembled peptide-lipid nanoconstructs that can undergo injury site-selective adhesion and subsequently promote site-directed active platelet aggregation, thus mimicking platelet's primary hemostatic actions. For injury site-selective adhesion, we have utilized a coagulation factor FVIII-derived VWF-binding peptide (VBP). FVIII binds to VWF's D'-D3 domain while natural platelet GPIbα binds to VWF's A1 domain. Therefore, we hypothesized that the VBP-decorated nanoconstructs will adhere to VWF without mutual competition with natural platelets. We further hypothesized that the adherent VBP-decorated constructs can enhance platelet aggregation when co-decorated with a fibrinogen-mimetic peptide (FMP). To test these hypotheses, we used glycocalicin to selectively block VWF's A1 domain and, using fluorescence microscopy, studied the binding of fluorescently labeled VBP-decorated nanoconstructs versus platelets to ristocetin-treated VWF. Subsequently, we co-decorated the nanoconstructs with VBP and FMP and incubated them with human platelets to study construct-mediated enhancement of platelet aggregation. Decoration with VBP resulted in substantial construct adhesion to ristocetin-treated VWF even if the A1-domain was blocked by glycocalicin. In comparison, such A1-blocking resulted in significant reduction of platelet adhesion. Without A1-blocking, the VBP-decorated constructs and natural platelets could adhere to VWF concomitantly. Furthermore, the constructs co-decorated with VBP and FMP enhanced active platelet aggregation. The results indicate significant promise in utilizing the FVIII-derived VBP in developing synthetic platelet analogs that do not interfere with VWF-binding of natural platelets but allow site-directed enhancement of platelet aggregation when combined with FMP. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr06400j

  8. Vitamin E supplementation reduces plasma vascular cell adhesion molecule-1 and von Willebrand factor levels and increases nitric oxide concentrations in hypercholesterolemic patients.

    PubMed

    Desideri, Giovambattista; Marinucci, Maria Contina; Tomassoni, Gianluca; Masci, Pier Giorgio; Santucci, Anna; Ferri, Claudio

    2002-06-01

    Up-regulation of vascular cell adhesion molecule-1 (VCAM-1) and reduced nitric oxide (NO) availability represent early characteristics of atherosclerosis. To evaluate whether the antioxidant vitamin E affected the circulating levels of soluble VCAM-1 (sVCAM-1) and the plasma metabolite of NO (nitrite+nitrate) in hypercholesterolemic patients, either vitamin E (either 400 IU or 800 IU/d for 8 wk) or placebo were randomly, double-blindly given to 36 hypercholesterolemic patients and 22 age- and sex-matched controls. At baseline hypercholesterolemic patients showed higher plasma sVCAM-1 (microg.liter(-1)) (591.2 +/- 132.5 vs. 505.0 +/- 65.6, P < 0.007) and lower NO metabolite (microM) levels (15.9 +/- 3.4 vs. 29.2 +/- 5.1, P < 0.0001) than controls. In hypercholesterolemic patients, 8 wk vitamin E (but not placebo) treatment significantly decreased circulating sVCAM-1 levels (400 IU: -148.9 +/- 84.6, P < 0.009; 800 IU: -204.0 +/- 75.7, P < 0.0001; placebo: -4.7 +/- 22.6, NS), whereas it increased NO metabolite concentrations (400 IU: +4.0 +/- 1.7, P < 0.02; 800 IU: +5.5 +/- 0.8, P < 0.0001; placebo: +0.1 +/- 1.1, NS) without affecting circulating low- density lipoprotein levels. Changes in both plasma sVCAM-1 and NO metabolite levels showed a trend to significantly correlate (r = -0.515, P = 0.010; and r = 0.435, P = 0.034, respectively) with changes in vitamin E concentrations induced by vitamin E supplementation. In conclusion, isolated hypercholesterolemia both increased circulating sVCAM-1 and reduced NO metabolite concentrations. Vitamin E supplementation counteracts these alterations, thus representing a potential tool for endothelial protection in hypercholesterolemic patients.

  9. Regulation of archaella expression by the FHA and von Willebrand domain-containing proteins ArnA and ArnB in Sulfolobus acidocaldarius.

    PubMed

    Reimann, Julia; Lassak, Kerstin; Khadouma, Sunia; Ettema, Thijs J G; Yang, Nuan; Driessen, Arnold J M; Klingl, Andreas; Albers, Sonja-Verena

    2012-10-01

    The ability of microorganisms to sense and respond to sudden changes in their environment is often based on regulatory systems comprising reversible protein phosphorylation. The archaellum (former: archaeal flagellum) is used for motility in Archaea and therefore functionally analogous to the bacterial flagellum. In contrast with archaellum-mediated movement in certain members of the Euryarchaeota, this process, including its regulation, remains poorly studied in crenarchaeal organisms like Sulfolobus species. Recently, it was shown in Sulfolobus acidocaldarius that tryptone limiting conditions led to the induction of archaella expression and assembly. Here we have identified two proteins, the FHA domain-containing protein ArnA and the vWA domain-containing protein ArnB that are involved in regulating archaella expression in S. acidocaldarius. Both proteins are phosphorylated by protein kinases in vitro and interact strongly in vivo. Phenotypic analyses revealed that these two proteins are repressors of archaella expression. These results represent the first step in understanding the networks that underlie regulation of cellular motility in Crenarchaeota and emphasize the importance of protein phosphorylation in the regulation of cellular processes in the Archaea.

  10. Establishment of reference intervals for von Willebrand factor antigen and eight coagulation factors in a Korean population following the Clinical and Laboratory Standards Institute guidelines.

    PubMed

    Jang, Ja-Hyun; Seo, Ja-Young; Bang, Sung-Hwan; Park, In-Ae; Kim, Hee-Jin; Kim, Sun-Hee

    2010-04-01

    Establishment of reference intervals for coagulation molecules is important but is costly and sometimes not feasible. Since reference intervals from manufacturers or the literature are mostly out of date or involved Western populations, the authors determined reference intervals for VWF: Ag and eight factors in a Korean population. VWF: Ag, factor VIII (FVIII), FII, FV, FVII, FIX, FX, FXI, and FXII were determined in Korean individuals visiting for routine checkup following the CLSI (Clinical and Laboratory Standards Institute) guidelines. Reagents by Diagnostica Stago were used on the STA Compact Analyzer (Diagnostica Stago). Exclusion criteria were medical history or laboratory findings that could affect the factor levels. Influence of demographic factors was analyzed. Mean +/- 2 x SD or central 95 percentile was used, as appropriate. We obtained data from 266 adults for VWF: Ag, 371 adults for FVIII, and minimum 136 adults for the rest. Reference interval for VWF was 51-176% (52-155% in blood group O and 71-186% for non-O). Reference interval for FVIII was 64-197% (55-150% in O and 77-205% in non-O). Reference interval for FII was 77-121%, FV 81-160%, FVII 68-149%, FIX 67-154%, FX 69-126%, FXI 59-138%, and FXII 48-177%. The medians of VWF: Ag, FVIII, and FIX were significantly higher in the elderly group (> or =60 years). We established local reference intervals for VWF: Ag and eight coagulation factors in a Korean population according to the CLSI guidelines. Significantly, different reference intervals were obtained in blood group O vs. non-O for VWF: Ag and FVIII. The reference intervals obtained in this study could be adopted in other clinical laboratories after appropriate validation.

  11. A double commutant theorem for Murray–von Neumann algebras

    PubMed Central

    Liu, Zhe

    2012-01-01

    Murray–von Neumann algebras are algebras of operators affiliated with finite von Neumann algebras. In this article, we study commutativity and affiliation of self-adjoint operators (possibly unbounded). We show that a maximal abelian self-adjoint subalgebra of the Murray–von Neumann algebra associated with a finite von Neumann algebra is the Murray–von Neumann algebra , where is a maximal abelian self-adjoint subalgebra of and, in addition, is . We also prove that the Murray–von Neumann algebra with the center of is the center of the Murray–von Neumann algebra . Von Neumann’s celebrated double commutant theorem characterizes von Neumann algebras as those for which , where , the commutant of , is the set of bounded operators on the Hilbert space that commute with all operators in . At the end of this article, we present a double commutant theorem for Murray–von Neumann algebras. PMID:22543165

  12. Indikatorenbasierte Bewertung von Entwurfsentscheidungen auf Systemebene

    NASA Astrophysics Data System (ADS)

    Freier, M.; Wenzler, A.; Mayer, T.; Gerlach, J.; Rosenstiel, W.

    2013-07-01

    Bei dem Entwurf von anwendungsspezifischen integrierten Schaltungen muss ein Entwickler zusätzliche Funktionen integrieren und die zunehmende Komplexität bewältigen. Für die Reduzierung der Kosten bleibt weiterhin die Verkürzung der benötigten Entwicklungszeit ein Ziel. Ein entscheidender Faktor dabei ist die zuverlässige Absicherung von Entwurfsentscheidungen in einer frühen Entwurfsphase. In der vorliegenden Arbeit wird eine Methode vorgestellt, die eine Bewertung von Entwurfsentscheidungen bei Systemmodellen mittels automatisch ermittelter Indikatoren ermöglichen soll. Die Systemmodelle können mit der Entwurfsumgebung MATLAB/Simulink oder in SystemC beschrieben sein.

  13. Childhood Picture of Dr. von Braun

    NASA Technical Reports Server (NTRS)

    1912-01-01

    This is a childhood picture of Dr. von Braun (center) with his brothers. Dr. Wernher von Braun was born in Wirsitz, Germany, March 23, 1912. His childhood dreams of marned space flight were fulfilled when giant Saturn rockets, developed under his direction at NASA's Marshall Space Flight Center, boosted the manned Apollo spacecraft to the Moon. His life was dedicated to expanding man's knowledge through the exploration of space.

  14. Dr. von Braun With Management Team

    NASA Technical Reports Server (NTRS)

    1961-01-01

    Dr. von Braun is shown in this photograph, which was probably taken in the early 1960s, with members of his management team. Pictured from left to right are, Werner Kuers, Director of the Manufacturing Engineering Division; Dr. Walter Haeussermarn, Director of the Astrionics Division; Dr. William Mrazek, Propulsion and Vehicle Engineering Division; Dr. von Braun; Dieter Grau, Director of the Quality Assurance Division; Dr. Oswald Lange, Director of the Saturn Systems Office; and Erich Neubert , Associate Deputy Director for Research and Development.

  15. Von Karman re-visited

    NASA Astrophysics Data System (ADS)

    McEligot, Donald M.; Nolan, Kevin P.; Walsh, Edmond J.

    2012-11-01

    A number of authors have presented extended versions of the integral momentum equation, allowing for perturbations or fluctuations in the boundary layer. ``Conventional wisdom'' is that these added terms can be neglected and one can apply the von Karman version directly. For two-dimensional turbulent boundary layers at high Reynolds numbers, experience shows this assumption to be reasonable. However, recent examination of entropy generation in bypass transition with zero pressure gradient shows a term for turbulence energy convection can be important in determining the energy dissipation coefficient [Walsh et al., JFE 2011]. The present study employs the direct numerical simulations of Zaki and Durbin [JFM 2006] for bypass transition with streamwise pressure gradients to quantify the additional normal stress term when estimating the skin friction coefficient via a momentum balance. It is found that this term becomes noticeable in the pre-transitional laminar boundary layer and can exceed forty per cent of Cf in the transition region. Thus, it should be included in such calculations. Partly supported by U. S. DoE EPSCoR office.

  16. An MRI Von Economo - Koskinas atlas.

    PubMed

    Scholtens, Lianne H; de Reus, Marcel A; de Lange, Siemon C; Schmidt, Ruben; van den Heuvel, Martijn P

    2016-12-28

    The cerebral cortex displays substantial variation in cellular architecture, a regional patterning that has been of great interest to anatomists for centuries. In 1925, Constantin von Economo and George Koskinas published a detailed atlas of the human cerebral cortex, describing a cytoarchitectonic division of the cortical mantle into over 40 distinct areas. Von Economo and Koskinas accompanied their seminal work with large photomicrographic plates of their histological slides, together with tables containing for each described region detailed morphological layer-specific information on neuronal count, neuron size and thickness of the cortical mantle. Here, we aimed to make this legacy data accessible and relatable to in vivo neuroimaging data by constructing a digital Von Economo - Koskinas atlas compatible with the widely used FreeSurfer software suite. In this technical note we describe the procedures used for manual segmentation of the Von Economo - Koskinas atlas onto individual T1 scans and the subsequent construction of the digital atlas. We provide the files needed to run the atlas on new FreeSurfer data, together with some simple code of how to apply the atlas to T1 scans within the FreeSurfer software suite. The digital Von Economo - Koskinas atlas is easily applicable to modern day anatomical MRI data and is made publicly available online.

  17. Dr. Wernher Von Braun with Dr. Christian Barnard.

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Dr. Christian Barnard Tours Marshall Space Flight Center. Shown in Dr. Von Braun's office are (left to right): Dr. Ernst Sthulinger, a representative from General Electric, Dr. Wernher Von Braun, Dr. Christian Barnard, and Dr. Eberhard Rees.

  18. Liouville-von Neumann molecular dynamics

    NASA Astrophysics Data System (ADS)

    Jakowski, Jacek; Morokuma, Keiji

    2009-06-01

    We present a novel first principles molecular dynamics scheme, called Liouville-von Neumann molecular dynamics, based on Liouville-von Neumann equation for density matrices propagation and Magnus expansion of the time-evolution operator. The scheme combines formally accurate quantum propagation of electrons represented via density matrices and a classical propagation of nuclei. The method requires a few iterations per each time step where the Fock operator is formed and von Neumann equation is integrated. The algorithm (a) is free of constraint and fictitious parameters, (b) avoids diagonalization of the Fock operator, and (c) can be used in the case of fractional occupation as in metallic systems. The algorithm is very stable, and has a very good conservation of energy even in cases when a good quality conventional Born-Oppenheimer molecular dynamics trajectories is difficult to obtain. Test simulations include initial phase of fullerene formation from gaseous C2 and retinal system.

  19. Mittelwert- und Arbeitstaktsynchrone Simulation von Dieselmotoren

    NASA Astrophysics Data System (ADS)

    Zahn, Sebastian

    Getrieben durch die immer restriktiveren Anforderungen an das Emissions- und Verbrauchsverhalten moderner Verbrennungsmotoren steigt die Komplexität von Motormanagementsystemen mit jeder Modellgeneration an. Damit geht nicht nur eine Zunahme des Softwareumfangs von Steuergeräten sondern zugleich ein deutlicher Anstieg des Applikations-, Vermessungs- und Testaufwandes einher. Zur Effizienzsteigerung des Software- und Funktionsentwicklungsprozesses haben sich daher in der Automobilindustrie sowie in Forschungsinstituten verschiedene modell- und simulationsbasierte Methoden wie die Model-in-the-Loop (MiL) Simulation, die Software-in-the-Loop (SiL) Simulation, das Rapid Control Prototyping (RCP) sowie die Hardware-in-the-Loop (HiL) Simulation etabliert.

  20. Level-Set-Segmentierung von Rattenhirn MRTs

    NASA Astrophysics Data System (ADS)

    Eiben, Björn; Kunz, Dietmar; Pietrzyk, Uwe; Palm, Christoph

    In dieser Arbeit wird die Segmentierung von Gehirngewebe aus Kopfaufnahmen von Ratten mittels Level-Set-Methoden vorgeschlagen. Dazu wird ein zweidimensionaler, kontrastbasierter Ansatz zu einem dreidimensionalen, lokal an die Bildintensität adaptierten Segmentierer erweitert. Es wird gezeigt, dass mit diesem echten 3D-Ansatz die lokalen Bildstrukturen besser berücksichtigt werden können. Insbesondere Magnet-Resonanz-Tomographien (MRTs) mit globalen Helligkeitsgradienten, beispielsweise bedingt durch Oberfiächenspulen, können auf diese Weise zuverlässiger und ohne weitere Vorverarbeitungsschritte segmentiert werden. Die Leistungsfähigkeit des Algorithmus wird experimentell an Hand dreier Rattenhirn-MRTs demonstriert.

  1. Dr. Wernher Von Braun presents a certificate

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Dr. Wernher Von Braun (left), director of the Marshall Space Flight Center, presents a humorous certificate to Major General Charles W. Eifler, commanding general of Redstone Arsenal, at the close of a farewell luncheon for the general prior to General Eifler moving to a new European duty station.

  2. [The Costantin Von Economo's lethargic encefalitis

    PubMed

    Pistacchio, E.

    1998-01-01

    Starting from the Constantin Von Economo's description of a "new" disease, the lethargic encephalitis, the author delineates the history of an infectious sleeping sickness that caused epidemics in Europe from 1917 to 1928 and led to create, in Italy, the "Institutes for Encephalitis".

  3. Dr. von Braun Visits Huntsville Boys Club

    NASA Technical Reports Server (NTRS)

    1961-01-01

    Dr. von Braun, Director of Marshall Space Flight Center (MSFC) and chairman of this year's United Givers Fund (UGF) drive at MSFC, takes time out from the problems of sending a man to the Moon to talk baseball with 11-year-old Randy Smith at the Huntsville Boys Club.

  4. Dr. von Braun Discusses 'Bottle Suit' Concept

    NASA Technical Reports Server (NTRS)

    1954-01-01

    Dr. Wernher von Braun (center), then Chief of the Guided Missile Development Division at Redstone Arsenal, Alabama, discusses a 'bottle suit' model with Dr. Heinz Haber (left), an expert on aviation medicine, and Willey Ley, a science writer on rocketry and space exploration. The three men were at the Disney studios appearing in the motion picture, entitled 'Man in Space.'

  5. A note on derivations of Murray–von Neumann algebras

    PubMed Central

    Kadison, Richard V.; Liu, Zhe

    2014-01-01

    A Murray–von Neumann algebra is the algebra of operators affiliated with a finite von Neumann algebra. In this article, we first present a brief introduction to the theory of derivations of operator algebras from both the physical and mathematical points of view. We then describe our recent work on derivations of Murray–von Neumann algebras. We show that the “extended derivations” of a Murray–von Neumann algebra, those that map the associated finite von Neumann algebra into itself, are inner. In particular, we prove that the only derivation that maps a Murray–von Neumann algebra associated with a factor of type II1 into that factor is 0. Those results are extensions of Singer’s seminal result answering a question of Kaplansky, as applied to von Neumann algebras: The algebra may be noncommutative and may even contain unbounded elements. PMID:24469831

  6. Platelet aggregation test

    MedlinePlus

    ... disorders Uremia (a result of kidney failure ) Von Willebrand disease (a bleeding disorder) Risks There is very little ... vasculitis Platelet count Polycythemia vera Prerenal azotemia Von Willebrand disease Review Date 1/27/2015 Updated by: Yi- ...

  7. What Causes Thrombocythemia and Thrombocytosis?

    MedlinePlus

    ... Topics Hemolytic Anemia Iron-Deficiency Anemia Stroke Von Willebrand Disease Send a link to NHLBI to someone by ... because of a condition that develops called von Willebrand disease . This condition affects the blood clotting process. After ...

  8. What Are the Signs and Symptoms of Thrombocythemia and Thrombocytosis?

    MedlinePlus

    ... Topics Hemolytic Anemia Iron-Deficiency Anemia Stroke Von Willebrand Disease Send a link to NHLBI to someone by ... high platelets counts is a condition called von Willebrand Disease . This condition affects the blood clotting process. In ...

  9. A double commutant theorem for Murray-von Neumann algebras.

    PubMed

    Liu, Zhe

    2012-05-15

    Murray-von Neumann algebras are algebras of operators affiliated with finite von Neumann algebras. In this article, we study commutativity and affiliation of self-adjoint operators (possibly unbounded). We show that a maximal abelian self-adjoint subalgebra A of the Murray-von Neumann algebra A(f)(R) associated with a finite von Neumann algebra R is the Murray-von Neumann algebra A(f)(A(0)), where A(0) is a maximal abelian self-adjoint subalgebra of R and, in addition, A(0) is A Π R. We also prove that the Murray-von Neumann algebra A(f)(C) with C the center of R is the center of the Murray-von Neumann algebra A(f)(R). Von Neumann's celebrated double commutant theorem characterizes von Neumann algebras R as those for which R'' = R, where R', the commutant of R, is the set of bounded operators on the Hilbert space that commute with all operators in R. At the end of this article, we present a double commutant theorem for Murray-von Neumann algebras.

  10. From the classical to the generalized von Karman and Marguerre-von Karman equations

    NASA Astrophysics Data System (ADS)

    Ciarlet, Philippe G.; Gratie, Liliana

    2006-06-01

    In this work, we describe and analyze two models that were recently proposed for modeling generalized von Karman plates and generalized Marguerre-von Karman shallow shells.First, we briefly review the "classical" von Karman and Marguerre-von Karman equations, their physical meaning, and their mathematical justification. We then consider the more general situation where only a portion of the lateral face of a nonlinearly elastic plate or shallow shell is subjected to boundary conditions of von Karman type, while the remaining portion is free. Using techniques from formal asymptotic analysis, we obtain in each case a two-dimensional boundary value problem that is analogous to, but is more general than, the classical equations.In particular, it is remarkable that the boundary conditions for the Airy function can still be determined on the entire boundary of the nonlinearly elastic plate or shallow shell solely from the data.Following recent joint works, we then reduce these more general equations to a single "cubic" operator equation, which generalizes an equation introduced by Berger and Fife, and whose sole unknown is the vertical displacement of the shell. We next adapt an elegant compactness method due to Lions for establishing the existence of a solution to this operator equation.

  11. Vascular Manifestations of von Recklinghausen's Disease

    PubMed Central

    Fye, Kenneth H.; Jacobs, Richard P.; Roe, Robert L.

    1975-01-01

    A casual relationship between von Recklinghausen's disease, or neurofibromatosis, and arteriolar abnormalities has been reported in the European literature. A patient was seen who had biopsy-proved neurofibromatosis and renovascular hypertension and retroperitoneal bleeding. An arteriographic study showed multiple small aneurysms throughout the coeliac axis, the superior mesenteric artery and in several small intrarenal vessels. Renal vein renin levels were elevated particularly in the right renal vein, supporting the diagnosis of renovascular hypertension. Both the aneurysms seen in angiographic studies and the retroperitoneal hemorrhage are probably vascular manifestations of von Recklinghausen's disease. Support for this conclusion is enhanced by the absence of clinical, laboratory or histologic data supporting the only tenable differential diagnosis, periarteritis nodosa. ImagesFigure 1.Figure 2.Figure 3.Figure 4. PMID:803743

  12. Management of the von Roos operator

    NASA Astrophysics Data System (ADS)

    Molinar-Tabares, Martin; Castro-Arce, Lamberto; Figueroa-Navarro, Carlos; Campos-Garcia, Julio

    When an electron is inside a semiconductor medium its effective mass rises from the shielding of the crystalline structure. When we have a semiconductor with a constant concentration the effective mass has a fixed value, and in this case, it can be easy to solve the Schrodinger equation of the particle, but if the concentration varies spatially, the effective mass will no longer constant and the solution can be difficult to find. The general form of the kinetic energy operator for a particle with variable mass is proposed for von Roos, this operator is characterized by some parameters whose values are subjected to a restriction. From a numerical solution of the Schrodinger equation we analyze the energies of an electron with position-dependent effective mass working with some values of the parameter of the von Roos operator. We acknowledge the support of SNI CONACYT.

  13. Herstellung von Chitosan und einige Anwendungen

    NASA Astrophysics Data System (ADS)

    Struszczyk, Marcin Henryk

    2001-05-01

    1. Die Deacetylierung von crabshell - Chitosan führte gleichzeitig zu einem drastischen Abfall der mittleren viscosimetrischen Molmasse ( Mv), insbesondere wenn die Temperatur und die Konzentration an NaOH erhöht werden. Diese Parameter beeinflussten jedoch nicht den Grad der Deacetylierung (DD). Wichtig ist jedoch die Quelle des Ausgangsmaterials: Chitin aus Pandalus borealis ist ein guter Rohstoff für die Herstellung von Chitosan mit niedrigem DD und gleichzeitig hoher mittlerer Mv, während Krill-Chitin (Euphausia superba) ein gutes Ausgangsmaterial zur Herstellung von Chitosan mit hohem DD und niedrigem Mv ist. Chitosan, das aus Insekten (Calliphora erythrocephala), unter milden Bedingungen (Temperatur: 100°C, NaOH-Konzentration: 40 %, Zeit: 1-2h ) hergestellt wurde, hatte die gleichen Eigenschaften hinsichtlich DD und Mv wie das aus Krill hergestellte Chitosan. Der Bedarf an Zeit, Energie und NaOH ist für die Herstellung von Insekten-Chitosan geringer als für crabshell-Chitosan vergleichbare Resultaten für DD und Mv. 2. Chitosan wurde durch den Schimmelpilz Aspergillus fumigatus zu Chitooligomeren fermentiert. Die Ausbeute beträgt 25%. Die Chitooligomere wurden mit Hilfe von HPLC und MALDI-TOF-Massenspektrmetrie identifiziert. Die Fermentationsmischung fördert die Immunität von Pflanzen gegen Bakterien und Virusinfektion. Die Zunahme der Immunität schwankt jedoch je nach System Pflanze-Pathogen. Die Fermentation von Chitosan durch Aspergillus fumigatus könnte eine schnelle und billige Methode zur Herstellung von Chitooligomeren mit guter Reinheit und Ausbeute sein. Eine partiell aufgereinigte Fermentationsmischung dieser Art könnte in der Landwirtschaft als Pathogeninhibitor genutzt werden. Durch kontrollierte Fermentation, die Chitooligomere in definierter Zusammensetzung (d.h. definierter Verteilung des Depolymerisationsgrades) liefert, könnte man zu Mischungen kommen, die für die jeweilige Anwendung eine optimale Bioaktivität besitzen. 3

  14. Verbesserung der Symmetrie von Hirnaufnahmen entlang der Sagittalebene

    NASA Astrophysics Data System (ADS)

    Ens, Konstantin; Wenzel, Fabian; Fischer, Bernd

    Die lokale Symmetrie von Hirnscans entlang der Sagittalebene zu ermitteln und zu modizifieren, ist für eine Reihe neurologischer Anwendungen interessant. Beispielsweise kann der voxelweise Vergleich von rechter und linker Hirnhälfte nur dann Aufschluss über die Lokalisierung von Läsionen geben, wenn durch Transformation ein Hirnscan eine möglichst hohe Symmetrie aufweist. Ein weiteres Anwendungsgebiet ist die Visualisierung von medialen Hirnschnitten, für die die Trennfläche beider Hirnhälfte möglichst eben sein sollte. Diese Arbeit stellt die Entwicklung eines Verfahrens vor, mit dessen Hilfe die Symmetrie von Hirnaufnahmen entlang der Sagittalebene verbessert werden kann. Dies geschieht unter Verwendung von aktiven Konturen, die mit Hilfe einer neuartigen Kostenfunktion gesteuert werden. Experimente am Ende der Arbeit mit strukturellen Kernspinaufnahmen demonstrieren die Leistungsfähigkeit des Verfahrens.

  15. Portrait of Dr. Von Braun with Walt Disney, 1954.

    NASA Technical Reports Server (NTRS)

    1954-01-01

    Marshall Center Director Dr. Wernher Von Braun is pictured with Walt Disney during a visit to the Marshall Space Flight Center in 1954. In the 1950s, Dr. Von Braun while working in California on the Saturn project, also worked with Disney studios as a technical director in making three films about Space Exploration for television. Disney's tour of Marshall in 1965 was Von Braun's hope for a renewed public interest in the future of the Space Program at NASA.

  16. Dr. von Braun and Army Ballistics Missile Agency (ABMA) Group

    NASA Technical Reports Server (NTRS)

    1959-01-01

    This photograph of Dr. von Braun, shown here to the left of General Bruce Medaris, was taken in the fall of 1959, immediately prior to Medaris' retirement from the Army. At the time, von Braun and his associates worked for the Army Ballistics Missile Agency in Huntsville, Alabama. Those in the photograph have been identified as Ernst Stuhlinger, Frederick von Saurma, Fritz Mueller, Hermarn Weidner, E.W. Neubert (partially hidden), W.A. Mrazek, Karl Heimburg, Arthur Rudolph, Otto Hoberg, von Braun, Oswald Lange, Medaris, Helmut Hoelzer, Hans Maus, E.D. Geissler, Hans Heuter, and George Constan.

  17. PT2385 for the Treatment of Von Hippel-Lindau Disease-Associated Clear Cell Renal Cell Carcinoma

    ClinicalTrials.gov

    2017-04-04

    VHL Gene Mutation; VHL; VHL Syndrome; VHL Gene Inactivation; Von Hippel; Von Hippel-Lindau Disease; Von Hippel's Disease; Von Hippel-Lindau Syndrome, Modifiers of; Clear Cell Renal Cell Carcinoma; Clear Cell RCC; ccRCC

  18. Approximating incompatible von Neumann measurements simultaneously

    SciTech Connect

    Heinosaari, Teiko; Jivulescu, Maria Anastasia; Reitzner, Daniel; Ziman, Mario

    2010-09-15

    We study the problem of performing orthogonal qubit measurements simultaneously. Since these measurements are incompatible, one has to accept additional imprecision. An optimal joint measurement is the one with the least possible imprecision. All earlier considerations of this problem have concerned only joint measurability of observables, while in this work we also take into account conditional state transformations (i.e., instruments). We characterize the optimal joint instrument for two orthogonal von Neumann instruments as being the Lueders instrument of the optimal joint observable.

  19. [Albrecht von Haller. An illustrious ancestor].

    PubMed

    Peiper, H-J

    2008-05-01

    Albrecht von Haller (1708-1777) was one of the most famous and important men of the eighteenth century. His achievements make him comparable with Lessing and Newton. In Blumenbach's opinion he was one of the enlightenment's greatest thinkers in both versatility and depth. He contributed significantly to developments in medicine, physiology, botany, pharmacology, theology, literature, editing, chronicles, biography, geography, and during his later years in Switzerland jurisprudence and agrarian reform. On the occasion of the 300th anniversary of his birth, important scientific landmarks in his life are described, with special attention to his achievements in the fields of anatomy, physiology, surgery, and experimental research.

  20. Group Theoretical Interpretation of von Neumann's Theorem on Composite Systems.

    ERIC Educational Resources Information Center

    Bergia, S.; And Others

    1979-01-01

    Shows that von Neumann's mathematical theorem on composite systems acquires a transparent physical meaning with reference to a suitable physical example; a composite system in a state of definite angular momentum. Gives an outline of the theorem, and the results are restated in Dirac's notation, thus generalizing von Neumann's results which were…

  1. Virtualized Optical Network (VON) for Future Internet and Applications

    NASA Astrophysics Data System (ADS)

    Jinno, Masahiko; Tsukishima, Yukio; Takara, Hidehiko; Kozicki, Bartlomiej; Sone, Yoshiaki; Sakano, Toshikazu

    A virtualized optical network (VON) is proposed as a key to implementing increased agility and flexibility into the future Internet and applications by providing any-to-any connectivity with the appropriate optical bandwidth at the appropriate time. The VON is enabled by introducing optical transparentization and optical fine granular grooming based on optical orthogonal frequency division multiplexing.

  2. Rare liver tumor: symptomatic giant von Meyenburg complex

    PubMed Central

    Singh, Yardesh; Cawich, Shamir O.; Ramjit, Chunilal; Naraynsingh, Vijay

    2016-01-01

    von Meyenburg complexes are hamartomas that arise from intra-hepatic bile ducts. Symptomatic lesions are uncommon and giant lesions are exceedingly rare. When encountered, they should be excised because there are reports of malignant change in large, symptomatic lesions. We report a case of a symptomatic giant von Meyenburg complex. PMID:28068648

  3. Victor or Villain? Wernher von Braun and the Space Race

    ERIC Educational Resources Information Center

    O'Brien, Jason L.; Sears, Christine E.

    2011-01-01

    Set during the Cold War and space race, this historical role-play focuses on Wernher von Braun's involvement in and culpability for the use of slave laborers to produce V-2 rockets for Nazi Germany. Students will grapple with two central questions. Should von Braun have been allowed to emigrate to the United States given his affiliation with the…

  4. Dr. von Braun Tries Out the Neutral Buoyancy Simulator (NBS)

    NASA Technical Reports Server (NTRS)

    1967-01-01

    Marshall Space Flight Center (MSFC) Director, Dr. von Braun, submerges after spending some time under water in the MSFC Neutral Buoyancy Simulator (NBS). Weighted to a neutrally buoyant condition, Dr. von Braun was able to perform tasks underwater which simulated weightless conditions found in space.

  5. Dr. von Braun Tries Out the Neutral Buoyancy Simulator (NBS)

    NASA Technical Reports Server (NTRS)

    1967-01-01

    Astronaut L. Gordon Cooper checks the neck ring of a space suit worn by Marshall Space Flight Center (MSFC) Director, Dr. von Braun before he submerges into the water of the MSFC Neutral Buoyancy Simulator (NBS). Wearing a pressurized suit and weighted to a neutrally buoyant condition, Dr. von Braun was able to perform tasks underwater which simulated weightless conditions found in space.

  6. Dr. von Braun Tries Out the Neutral Buoyancy Simulator (NBS)

    NASA Technical Reports Server (NTRS)

    1967-01-01

    Marshall Space Flight Center (MSFC) Director, Dr. von Braun, is shown leaving the suiting-up van wearing a pressure suit prepared for a tryout in the MSFC Neutral Buoyancy Simulator (NBS). Weighted to a neutrally buoyant condition, Dr. von Braun was able to perform tasks underwater which simulated weightless conditions found in space.

  7. Wernher von Braun and Saturn IB on Launch Pad

    NASA Technical Reports Server (NTRS)

    1968-01-01

    Dr. Wernher von Braun stands in front of a Saturn IB launch vehicle at Kennedy Space Flight Center. Dr. von Braun led a team of German rocket scientists, called the Rocket Team, to the United States, first to Fort Bliss/White Sands, later being transferred to the Army Ballistic Missile Agency at Redstone Arsenal in Huntsville, Alabama. They were further transferred to the newly established NASA/Marshall Space Flight Center (MSFC) in Huntsville, Alabama in 1960, and Dr. von Braun became the first Center Director. Under von Braun's direction, MSFC developed the Mercury-Redstone, which put the first American in space; and later the Saturn rockets, Saturn I, Saturn IB, and Saturn V. The Saturn V launch vehicle put the first human on the surface of the Moon, and a modified Saturn V vehicle placed Skylab, the first United States' experimental space station, into Earth orbit. Dr. von Braun was MSFC Director from July 1960 to February 1970.

  8. Approximate von Neumann entropy for directed graphs.

    PubMed

    Ye, Cheng; Wilson, Richard C; Comin, César H; Costa, Luciano da F; Hancock, Edwin R

    2014-05-01

    In this paper, we develop an entropy measure for assessing the structural complexity of directed graphs. Although there are many existing alternative measures for quantifying the structural properties of undirected graphs, there are relatively few corresponding measures for directed graphs. To fill this gap in the literature, we explore an alternative technique that is applicable to directed graphs. We commence by using Chung's generalization of the Laplacian of a directed graph to extend the computation of von Neumann entropy from undirected to directed graphs. We provide a simplified form of the entropy which can be expressed in terms of simple node in-degree and out-degree statistics. Moreover, we find approximate forms of the von Neumann entropy that apply to both weakly and strongly directed graphs, and that can be used to characterize network structure. We illustrate the usefulness of these simplified entropy forms defined in this paper on both artificial and real-world data sets, including structures from protein databases and high energy physics theory citation networks.

  9. Quantenphysik Interferometrie von C70-Molekülen

    NASA Astrophysics Data System (ADS)

    Ziegler, Thomas

    2002-05-01

    Interferenzversuche mit Neutronen und schweren Atomen stellen kein großes Problem mehr dar, selbst die Welleneigenschaften von C60-und C70-Molekülen wurden bereits nachgewiesen. Allerdings stößt man bei der Realisation immer feinerer Gitter mit Gitterkonstanten von etwa 100 nm im Fall dieser Moleküle auf technische Probleme. Wissenschaftlern der Universität Wien ist es jüngst gelungen, ein so genanntes Talbot-Lau-Interferometer zu realisieren und die Welleneigenschaften von C70 mit einer bislang unerreichten Qualität nachzuweisen [1].

  10. Valence bond and von Neumann entanglement entropy in Heisenberg ladders.

    PubMed

    Kallin, Ann B; González, Iván; Hastings, Matthew B; Melko, Roger G

    2009-09-11

    We present a direct comparison of the recently proposed valence bond entanglement entropy and the von Neumann entanglement entropy on spin-1/2 Heisenberg systems using quantum Monte Carlo and density-matrix renormalization group simulations. For one-dimensional chains we show that the valence bond entropy can be either less or greater than the von Neumann entropy; hence, it cannot provide a bound on the latter. On ladder geometries, simulations with up to seven legs are sufficient to indicate that the von Neumann entropy in two dimensions obeys an area law, even though the valence bond entanglement entropy has a multiplicative logarithmic correction.

  11. Hermann von Helmholtz and his students

    NASA Astrophysics Data System (ADS)

    Mulligan, Joseph F.

    1989-01-01

    During the years 1871-1888, when Hermann von Helmholtz was professor of physics at the University of Berlin, physicists from all over the world flocked to Berlin to study and do research with him. Among these were the German physicists Max Planck, Heinrich Kayser, Eugen Goldstein, Wilhelm Wien, and Heinrich Hertz, and Americans Henry Rowland, A. A. Michelson, and Michael Pupin. Examples of Helmholtz's scientific and personal interactions with these students and research associates show why he is justly considered the outstanding physics mentor of the 19th century. Both his ideas and his students played a major role in the development of physics in the late 19th and early 20th centuries.

  12. Von Economo neurons in the elephant brain.

    PubMed

    Hakeem, Atiya Y; Sherwood, Chet C; Bonar, Christopher J; Butti, Camilla; Hof, Patrick R; Allman, John M

    2009-02-01

    Von Economo neurons (VENs), previously found in humans, all of the great ape species, and four cetacean species, are also present in African and Indian elephants. The VENs in the elephant are primarily found in similar locations to those in the other species. They are most abundant in the frontoinsular cortex (area FI) and are also present at lower density in the anterior cingulate cortex. Additionally, they are found in a dorsolateral prefrontal area and less abundantly in the region of the frontal pole. The VEN morphology appears to have arisen independently in hominids, cetaceans, and elephants, and may reflect a specialization for the rapid transmission of crucial social information in very large brains.

  13. Johann von Lamont: A Pioneer in Geomagnetism

    NASA Astrophysics Data System (ADS)

    Soffel, Heinrich

    2006-06-01

    The 200th birthday of John Lamont (1805-1879, Figure 1), a pioneer in the study of geomagnetism, was marked on 13 December 2005. Lamont founded the Munich Geomagnetic Observatory in 1840 and was a member of the group of scientists including Carl Friedrich Gauss, Alexander von Humboldt, Eduard Sabine, Jonas Angstrøm, Humphret Lloyd, Adolf Kupffer, Karl Kreil, and Adolphe Quetelet who composed the Göttingen Magnetic Union. They organized an international network of geomagnetic observatories [Barraclough et al., 1992]. The present knowledge of the geomagnetic field and its secular variation is largely based on the data collected by the global network of geomagnetic observatories during the last 170 years. Lamont's talents and his dedication and enthusiasm for discovery are reflected in the depth and scope of his contributions to a broad variety of natural sciences such as astronomy, meteorology, geomagnetism, and geodesy. However, this article just touches on his merits in geomagnetism.

  14. Johann Philipp von Wurzelbau (1651-1725)

    NASA Astrophysics Data System (ADS)

    Gaab, Hans

    During the turn of the 17th to the 18th century, Johann Philipp von Wurzelbau was the best-known astronomer in Nuremberg. He was a trained merchant, who busied himself in his free hours with astronomy. In the 1680s he became known for his accurate observations of lunar and solar eclipses. At the end of the 1680s he left his trade, and from 1691, he was completely occupied with astronomy. To that end, he constructed a small octagonal observing tower on the roof of his house at Spitzenberg 4. He took the measurement of the solar path and determined the geographical coordinates of Nuremberg. The calendar reform also played a major role in his life.

  15. Dr. von Braun at the Manufacturing and Engineering Laboratory

    NASA Technical Reports Server (NTRS)

    1967-01-01

    Dr. von Braun, Director of the Marshall Space Flight Center, listens attentively to a briefing on the metal forming techniques by Dr. Mathias Siebel of the Manufacturing and Engineering Laboratory at MSFC on October 17, 1967.

  16. 33. HISTORIC VIEW OF WERNHER VON BRAUN LOOKS THROUGH THE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    33. HISTORIC VIEW OF WERNHER VON BRAUN LOOKS THROUGH THE PERISCOPE FROM THE CONTROL ROOM AT TEST STAND NO. 1, PEENEMUENDE. - Marshall Space Flight Center, Redstone Rocket (Missile) Test Stand, Dodd Road, Huntsville, Madison County, AL

  17. Fletcher and von Braun at Apollo 15 launch

    NASA Technical Reports Server (NTRS)

    1971-01-01

    Recently appointed NASA Administrator Dr. James C. Fletcher, left, and Dr. Wernher von Braun, Deputy Associate Administrator for Planning, monitor Apollo 15 prelaunch activities in Firing Room 1 of the Launch Control Center and the Kennedy Space Center, Florida.

  18. Dr. Wernher Von Braun examines a ruby crystal.

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Dr. Wernher Von Braun (right), director of the Marshall Space Flight Center, and Dr. Eberhard Rees (left), deputy director, technical, examine a ruby crystal used in laser experiments in the Marshall Center's Space Sciences Laboratory.

  19. 7. Historic American Buildings Survey, Charles Von Urban, Photographer June ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    7. Historic American Buildings Survey, Charles Von Urban, Photographer June 23, 1936, INTERIOR-PARLOR SHOWING FIREPLACE, WINDOWN TRIM, AND CORNICE. - George Fordham House, 329 Cherry Street, New York County, NY

  20. Physik gestern und heute Von der Metallstange zum Hochenergielaser

    NASA Astrophysics Data System (ADS)

    Heering, Peter

    2002-05-01

    Im Mai 1752 wurde in Marly bei Paris auf Anregung des amerikanischen Forschers und Politikers Benjamin Franklin erstmals die elektrische Natur des Blitzes nachgewiesen. Damals beschrieb Franklin auch eine technische Vorrichtung, die als Schutz von Gebäuden vor Blitzschlägen dienen sollte: den Blitzableiter. Diese aus heutiger Sicht scheinbar triviale Vorrichtung wurde aber keineswegs unmittelbar akzeptiert. Und bis heute ist die Forschung zum Schutz von Einrichtungen vor Blitzschlägen nicht abgeschlossen.

  1. Wernher von Braun with German Officers and Others

    NASA Technical Reports Server (NTRS)

    1942-01-01

    General Erich Fellgiebel, head of the German Army Information Service during World War II, congratulates members of the von Braun rocket team from Peenemunde for their October 3, 1942 A4 flight. Pictured front center is General Erich Fellgiebel. Shaking hands are General Walter Dornberger (left) and General Janssen, commanding officer of Peenemuende with Rudolph Hermarn to their right. Picture left to right in the back row are Wernher von Braun, Captain Stoelzel, Luftwaffe, and Dr. Gerhard Reisig.

  2. Quantum control by von Neumann measurements

    NASA Astrophysics Data System (ADS)

    Pechen, Alexander; Il'in, Nikolai; Shuang, Feng; Rabitz, Herschel

    2006-11-01

    A general scheme is presented for controlling quantum systems using evolution driven by nonselective von Neumann measurements, with or without an additional tailored electromagnetic field. As an example, a two-level quantum system controlled by nonselective quantum measurements is considered. The control goal is to find optimal system observables such that consecutive nonselective measurement of these observables transforms the system from a given initial state into a state which maximizes the expected value of a target operator (the objective). A complete analytical solution is found including explicit expressions for the optimal measured observables and for the maximal objective value given any target operator, any initial system density matrix, and any number of measurements. As an illustration, upper bounds on measurement-induced population transfer between the ground and the excited states for any number of measurements are found. The anti-Zeno effect is recovered in the limit of an infinite number of measurements. In this limit the system becomes completely controllable. The results establish the degree of control attainable by a finite number of measurements.

  3. Richard von Volkmann: surgeon and Renaissance man.

    PubMed

    Willy, Christian; Schneider, Peter; Engelhardt, Michael; Hargens, Alan R; Mubarak, Scott J

    2008-02-01

    Richard von Volkmann (1830-1889), one of the most important surgeons of the 19(th) century, is regarded as one of the fathers of orthopaedic surgery. He was a contemporary of Langenbeck, Esmarch, Lister, Billroth, Kocher, and Trendelenburg. He was head of the Department of Surgery at the University of Halle, Germany (1867-1889). His popularity attracted doctors and patients from all over the world. He was the lead physician for the German military during two wars. From this experience, he compared the mortality of civilian and war injuries and investigated the general poor hygienic conditions in civilian hospitals. This led him to introduce the "antiseptic technique" to Germany that was developed by Lister. His powers of observation and creativity led him to findings and achievements that to this day bear his name: Volkmann's contracture and the Hueter-Volkmann law. Additionally, he was a gifted writer; he published not only scientific literature but also books of children's fairy tales and poems under the pen name of Richard Leander, assuring him a permanent place in the world of literature as well as orthopaedics.

  4. Berechnung von Nichtlinearitätsparametern von RF MOS Mischern mittels Volterra-Reihen

    NASA Astrophysics Data System (ADS)

    Susic, A.; Darrat, A. H.; Mathis, W.

    2011-07-01

    Die Nichtlinearität einer Mischerschaltung bezüglich des Informationssignals führt zu unerwünschten Spektralanteilen am Ausgang des Mischers. Da nicht alle Spektralanteile kritisch sind, müssen bei einer Nichtlinearitätsanalyse nur bestimmte Spektralanteile ermittelt werden. In dieser Arbeit wird ein Verfahren zur Bestimmung der Spektralanteile der Zustandsgrößen im Mischer mit Hilfe der Volterra-Reihe gezeigt. Das Verfahren basiert auf die Methode der nichtlinearen Stromquellen. Es wird sowohl auf nicht-schaltende als auch schaltende Mischer angewendet. Hierbei wird der erste als ein zeitinvariantes System mit zwei Eingängen und der zweite als ein periodisch zeitvariantes System mit einem Eingang modelliert. Das Verfahren wird in dem Computeralgebraprogramm MAPLE für den einfach balancierten MOS Mischer implementiert. Es ermöglicht die Herleitung von semi-symbolischen Ausdrücken für die Spektralanteile in Abhängigkeit von den Entwurfsparametern. Die numerischen Ergebnisse des Verfahrens werden gegenüber Simulationen mit SpectreRF verglichen.

  5. The VITRO Score (Von Willebrand Factor Antigen/Thrombocyte Ratio) as a New Marker for Clinically Significant Portal Hypertension in Comparison to Other Non-Invasive Parameters of Fibrosis Including ELF Test

    PubMed Central

    Hametner, Stephanie; Ferlitsch, Arnulf; Ferlitsch, Monika; Etschmaier, Alexandra; Schöfl, Rainer; Ziachehabi, Alexander; Maieron, Andreas

    2016-01-01

    Background Clinically significant portal hypertension (CSPH), defined as hepatic venous pressure gradient (HVPG) ≥10 mmHg, causes major complications. HVPG is not always available, so a non-invasive tool to diagnose CSPH would be useful. VWF-Ag can be used to diagnose. Using the VITRO score (the VWF-Ag/platelet ratio) instead of VWF-Ag itself improves the diagnostic accuracy of detecting cirrhosis/ fibrosis in HCV patients. Aim This study tested the diagnostic accuracy of VITRO score detecting CSPH compared to HVPG measurement. Methods All patients underwent HVPG testing and were categorised as CSPH or no CSPH. The following patient data were determined: CPS, D’Amico stage, VITRO score, APRI and transient elastography (TE). Results The analysis included 236 patients; 170 (72%) were male, and the median age was 57.9 (35.2–76.3; 95% CI). Disease aetiology included ALD (39.4%), HCV (23.4%), NASH (12.3%), other (8.1%) and unknown (11.9%). The CPS showed 140 patients (59.3%) with CPS A; 56 (23.7%) with CPS B; and 18 (7.6%) with CPS C. 136 patients (57.6%) had compensated and 100 (42.4%) had decompensated cirrhosis; 83.9% had HVPG ≥10 mmHg. The VWF-Ag and the VITRO score increased significantly with worsening HVPG categories (P<0.0001). ROC analysis was performed for the detection of CSPH and showed AUC values of 0.92 for TE, 0.86 for VITRO score, 0.79 for VWF-Ag, 0.68 for ELF and 0.62 for APRI. Conclusion The VITRO score is an easy way to diagnose CSPH independently of CPS in routine clinical work and may improve the management of patients with cirrhosis. PMID:26895398

  6. Functional characterization of Vitellogenin_N domain, domain of unknown function 1943, and von Willebrand factor type D domain in vitellogenin of the non-bilaterian coral Euphyllia ancora: Implications for emergence of immune activity of vitellogenin in basal metazoan.

    PubMed

    Du, Xiaoyuan; Wang, Xia; Wang, Su; Zhou, Yang; Zhang, Yu; Zhang, Shicui

    2017-02-01

    Our understanding of the function of vitellogenin (Vg) in reproduction has undergone a transformation over the past decade in parallel with new insights into the role of Vg in immunity. However, the time when Vg was endowed with immunological activities during animal evolution remains elusive. Here we demonstrate for the first time that the recombinant proteins rVitellogenin_N, rDUF1943, and rVWD from Vg of the basal metazoan coral Euphyllia ancora not only interact with Gram-positive and negative bacteria as well as their conserved surface components LTA and LPS but also enhance phagocytosis of bacteria by macrophages. Moreover, challenge with LPS results in a marked up-regulation of vg in the coral E. ancora. These data suggest that E. ancora Vg, like that described in the bilaterian oviparous animals fish and amphioxus, is a molecule related to antibacterial defense, indicating that the timing of the emergence of immune role of Vg predates the divergence of the cnidarian (non-bilaterian) and bilaterian lineages.

  7. Locally Compact Quantum Groups. A von Neumann Algebra Approach

    NASA Astrophysics Data System (ADS)

    Van Daele, Alfons

    2014-08-01

    In this paper, we give an alternative approach to the theory of locally compact quantum groups, as developed by Kustermans and Vaes. We start with a von Neumann algebra and a comultiplication on this von Neumann algebra. We assume that there exist faithful left and right Haar weights. Then we develop the theory within this von Neumann algebra setting. In [Math. Scand. 92 (2003), 68-92] locally compact quantum groups are also studied in the von Neumann algebraic context. This approach is independent of the original C^*-algebraic approach in the sense that the earlier results are not used. However, this paper is not really independent because for many proofs, the reader is referred to the original paper where the C^*-version is developed. In this paper, we give a completely self-contained approach. Moreover, at various points, we do things differently. We have a different treatment of the antipode. It is similar to the original treatment in [Ann. Sci. & #201;cole Norm. Sup. (4) 33 (2000), 837-934]. But together with the fact that we work in the von Neumann algebra framework, it allows us to use an idea from [Rev. Roumaine Math. Pures Appl. 21 (1976), 1411-1449] to obtain the uniqueness of the Haar weights in an early stage. We take advantage of this fact when deriving the other main results in the theory. We also give a slightly different approach to duality. Finally, we collect, in a systematic way, several important formulas. In an appendix, we indicate very briefly how the C^*-approach and the von Neumann algebra approach eventually yield the same objects. The passage from the von Neumann algebra setting to the C^*-algebra setting is more or less standard. For the other direction, we use a new method. It is based on the observation that the Haar weights on the C^*-algebra extend to weights on the double dual with central support and that all these supports are the same. Of course, we get the von Neumann algebra by cutting down the double dual with this unique

  8. Biographical sketch: Georg Hermann von Meyer (1815-1892).

    PubMed

    Skedros, John G; Brand, Richard A

    2011-11-01

    This biographical sketch on Georg Hermann von Meyer highlights the interactions in the 1860s that von Meyer, a famous anatomist, had with Karl Culmann, a famous structural engineer and mathematician. The published papers from this interaction caught the attention of Julius Wolff and stimulated his development of the trajectorial hypothesis of bone adaptation--now called "Wolff's Law." The corresponding translations are provided: (1) von Meyer's 1867 paper that highlights the regularity of arched trabecular patterns in various human bones, and his discussions with Culmann about their possible mechanical relevance; and (2) Wolff's 1869 paper that first mentions the correspondence of stress trajectories in a solid, crane-like structure to the arched trabecular patterns in the proximal human femur. This biographical sketch on Georg Hermann von Meyer corresponds to the historic texts, The Classic: The Architecture of the Trabecular bone (by von Meyer), and The Classic: On the Significance of the Architecture of the Spongy Substance for the Question of Bone Growth. A preliminary publication (by Wolff) available at DOIs 10.1007/s11999-011-2041-5 , 10.1007/s11999-011-2042-4 .

  9. Periodisches Hitzdrahtverfahren zur Messung von Wärme- und Temperaturleitfähigkeit von geringen Stoffmengen

    NASA Astrophysics Data System (ADS)

    Griesinger, A.; Spindler, K.; Hahne, E.

    Zusammenfassung Es wird ein Meßverfahren zur gleichzeitigen Bestimmung der Wärme- und der Temperaturleitfähigkeit von geringen Stoffmengen beschrieben. Neben Messungen an hochviskosen Flüssigkeiten eignet sich das Verfahren besonders für Messungen an Pulver-Schüttungen. Das Meßverfahren basiert auf dem transienten Hitzdraht-Verfahren. In einem dünnen Platindraht fließt ein sinusförmiger Wechselstrom, der den Draht periodisch erwärmt. Es entstehen thermische Wellen, die in die umgebende Probe eindringen. Die Amplitude und die Phasenlage der thermischen Wellen in der Probe hängen von der Temperaturleitfähigkeit a und der Wärmeleitfähigkeit λ der Probe ab. Die Temperaturschwingung in der Probe wird mit Hilfe des Platindrahtes gemessen, der gleichzeitig als Widerstandsthermometer eingesetzt wird. Meßwerte von Wasser und Glycerin zeigen eine gute Übereinstimmung mit Literaturwerten. Das Meßverfahren zeichnet sich dadurch aus, daß zur Bestimmung der Wärme- und Temperaturleitfähigkeit nur 13 ml einer Probe benötigt werden. Es werden Meßwerte einer Zeolith-Schüttung unter Wasserstoffbeladung dargestellt. A measuring procedure for the simultaneous determination of the thermal conductivity and thermal diffusivity of small quantities is described. The procedure is suited for high-viscous fluids and for powdery material. The measuring principle is based on the transient hot-wire method. A sinusoidal alternating current flows through a thin platinum wire and heats up the wire periodically. This results in thermal waves, which penetrate into the surrounding sample. The amplitude and the phase shift of the thermal waves depend on the thermal diffusivity ``a'' and the thermal conductivity ``λ'' of the sample. The temperature oscillation in the sample is measured by means of the platinum wire, which is simultaneously applied as a resistance thermometer. The values measured for water and glycerine correspond well to those given in literature. Results of the

  10. The smooth entropy formalism for von Neumann algebras

    NASA Astrophysics Data System (ADS)

    Berta, Mario; Furrer, Fabian; Scholz, Volkher B.

    2016-01-01

    We discuss information-theoretic concepts on infinite-dimensional quantum systems. In particular, we lift the smooth entropy formalism as introduced by Renner and collaborators for finite-dimensional systems to von Neumann algebras. For the smooth conditional min- and max-entropy, we recover similar characterizing properties and information-theoretic operational interpretations as in the finite-dimensional case. We generalize the entropic uncertainty relation with quantum side information of Tomamichel and Renner and discuss applications to quantum cryptography. In particular, we prove the possibility to perform privacy amplification and classical data compression with quantum side information modeled by a von Neumann algebra.

  11. Henry Cavendish, Johann von Soldner, and the deflection of light

    NASA Astrophysics Data System (ADS)

    Will, Clifford M.

    1988-05-01

    The gravitational deflection of light based on Newtonian theory and the corpuscular model of light was calculated, but never published, around 1784 by Henry Cavendish, almost 20 years earlier than the first published calculation by Johann Georg von Soldner. The two results are slightly different because, while Cavendish treated a light ray emitted from infinity, von Soldner treated a light ray emitted from the surface of the gravitating body. At the first order of approximation, they agree with each other; both are one-half the value predicted by general relativity and confirmed by experiment.

  12. An Accurate von Neumann's Law for Three-Dimensional Foams

    SciTech Connect

    Hilgenfeldt, Sascha; Kraynik, Andrew M.; Koehler, Stephan A.; Stone, Howard A.

    2001-03-19

    The diffusive coarsening of 2D soap froths is governed by von Neumann's law. A statistical version of this law for dry 3D foams has long been conjectured. A new derivation, based on a theorem by Minkowski, yields an explicit analytical von Neumann's law in 3D which is in very good agreement with detailed simulations and experiments. The average growth rate of a bubble with F faces is shown to be proportional to F{sup 1/2} for large F , in contrast to the conjectured linear dependence. Accounting for foam disorder in the model further improves the agreement with data.

  13. The smooth entropy formalism for von Neumann algebras

    SciTech Connect

    Berta, Mario; Furrer, Fabian; Scholz, Volkher B.

    2016-01-15

    We discuss information-theoretic concepts on infinite-dimensional quantum systems. In particular, we lift the smooth entropy formalism as introduced by Renner and collaborators for finite-dimensional systems to von Neumann algebras. For the smooth conditional min- and max-entropy, we recover similar characterizing properties and information-theoretic operational interpretations as in the finite-dimensional case. We generalize the entropic uncertainty relation with quantum side information of Tomamichel and Renner and discuss applications to quantum cryptography. In particular, we prove the possibility to perform privacy amplification and classical data compression with quantum side information modeled by a von Neumann algebra.

  14. Ernst von Glasersfeld's Radical Constructivism and Truth as Disclosure

    ERIC Educational Resources Information Center

    Joldersma, Clarence W.

    2011-01-01

    In this essay Clarence Joldersma explores radical constructivism through the work of its most well-known advocate, Ernst von Glasersfeld, who combines a sophisticated philosophical discussion of knowledge and truth with educational practices. Joldersma uses Joseph Rouse's work in philosophy of science to criticize the antirealism inherent in…

  15. Dr. von Braun Conferring With NASA Headquarters Officials

    NASA Technical Reports Server (NTRS)

    1961-01-01

    This photograph, dated November 13, 1961, shows Dr. von Braun conferring with two officials from NASA Headquarters. Dr. Brainered Holmes is on the left. Dr. Nicholas Golovin is in the center. Holmes was Director of NASA's Office of Marned Space Flight. Golovin was Director of Systems Engineering at Headquarters.

  16. Von Kármán between Aachen and Pasadena

    NASA Astrophysics Data System (ADS)

    Krause, Egon; Kalkmann, Ulrich

    2013-05-01

    In the Introduction the reader is referred back to the academic ceremonials held after Theodore von Kármán's death in Aachen in May 1963. His work as the first director of the Aerodynamisches Institut (Institute of Aerodynamics) of the RWTH Aachen University of Technology from 1913 on and his initiative to re-establish international cooperation after World War I, resulting in the International Union of Theoretical and Applied Mechanics (IUTAM), are commented on. The following chapter describes von Kármán's relation to his former teacher Ludwig Prandtl. Some of von Kármán's scientific contributions during his time in Aachen are briefly reviewed. Thereafter, his first contacts to the California Institute of Technology are covered. Finally, the scientific and political circumstances, which led to von Kármán's decision to leave Germany in the early thirties, are elucidated in some detail. The English translation of the titles of the Aachen papers is given in Appendix I.

  17. Dr. Wernher Von Braun near the mobile launcher.

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Dr. George Mueller, NASA associate administrator for manned space flight, and Dr. Wernher Von Braun (right), director of the Marshall Space Flight Center, are seen near the mobile launcher carrying a 363 foot tall Saturn V space launch vehicle as the rocket is rolled from the vehicle assembly building at KSC for its three mile trip to the launch pad.

  18. Wernher von Braun: Reflections on His Contributions to Space Exploration

    NASA Technical Reports Server (NTRS)

    Goldman, Arthur E.

    2012-01-01

    In 1950, Dr. Wernher von Braun and approximately 100 of his team members came to Huntsville, Alabama, to begin work with the Army on what would later become America's historic space program. He would later serve as the first director of the Marshall Space Flight Center and led the development of the Saturn V launch vehicle that launched seven crewed American mission to the moon, as well as America s first space station, Skylab. Von Braun is best known for his team s technical achievements. He realized his dream of exploring outer space by helping place humans on the moon. His engineering and managerial talent during the Apollo era had contributed to a technological revolution. He was by all accounts a good engineer, but he was only one among many. What set Von Braun apart were his charisma, his vision, and his leadership skills. He inspired loyalty and dedication in the people around him. He understood the importance of communicating his vision to his team, to political and business leaders and the public. Today, the Marshall Center continues his vision by pursuing engineering and scientific projects that will continue to open space to exploration. This presentation will discuss Von Braun's impact on Huntsville, the Marshall Center, the nation and the world and look at his contributions in context of where world space exploration is today.

  19. von Braun Examines Bendix Mobility Test Article (MTA)

    NASA Technical Reports Server (NTRS)

    1964-01-01

    Marshall Space Flight Center (MSFC) director, Wernher von Braun, and others examine one concept of a possible Lunar Roving Vehicle (LRV) built by the Bendix Corporation. The data provided by the MTA helped in designing the LRV, developed under the direction of MSFC. The LRV was designed to allow Apollo astronauts a greater range of mobility during lunar exploration missions.

  20. von Braun Examines Bendix Mobility Test Article (MTA)

    NASA Technical Reports Server (NTRS)

    1965-01-01

    Marshall Space Flight Center (MSFC) director, Wernher von Braun, and a visitor, examine one concept of a possible Lunar Roving Vehicle (LRV) built by the Bendix Corporation. The data provided by the MTA helped in designing the LRV, developed under the direction of MSFC. The LRV was designed to allow Apollo astronauts a greater range of mobility during lunar exploration missions.

  1. Dr. von Braun With a Model of a Launch Vehicle

    NASA Technical Reports Server (NTRS)

    1950-01-01

    Dr. von Braun stands beside a model of the upper stage (Earth-returnable stage) of the three-stage launch vehicle built for the series of the motion picture productions of space flight produced by Walt Disney in the mid-1950's.

  2. Treasure in the Library Attic: Von Ranke at Syracuse.

    ERIC Educational Resources Information Center

    Coville, Bruce

    1984-01-01

    Traces history of private library of German scholar, Leopold von Ranke, which was purchased by Syracuse University in 1888. Efforts of librarian Charles W. Bennett in 1870s and Professor James Powell beginning in late 1960s, and restoration and cataloging of collection are highlighted. Items from the collection are noted. (EJS)

  3. The Influence of Field Marshal Colmar Von Der Goltz on Ottoman Military Effectiveness in Mesopotamia: December 1915 to April 1916

    DTIC Science & Technology

    2012-02-23

    the Ottoman Fifth Army was activated to defend the Dardanelles, and the Ottomans gave Limon von Sanders command. With Limon von Sanders’ move to...Fifth Army, von der Goltz took command of the First Army and the German military mission which were both previously commanded by Limon von Sanders.51

  4. Platelet activation risk index as a prognostic thrombosis indicator

    PubMed Central

    Zlobina, K. E.; Guria, G. Th.

    2016-01-01

    Platelet activation in blood flow under high, overcritical shear rates is initiated by Von Willebrand factor. Despite the large amount of experimental data that have been obtained, the value of the critical shear rate, above which von Willebrand factor starts to activate platelets, is still controversial. Here, we recommend a theoretical approach to elucidate how the critical blood shear rate is dependent on von Willebrand factor size. We derived a diagram of platelet activation according to the shear rate and von Willebrand factor multimer size. We succeeded in deriving an explicit formula for the dependence of the critical shear rate on von Willebrand factor molecule size. The platelet activation risk index was introduced. This index is dependent on the flow conditions, number of monomers in von Willebrand factor, and platelet sensitivity. Probable medical applications of the platelet activation risk index as a universal prognostic index are discussed. PMID:27461235

  5. Reversible Hypothermia-Induced Inhibition of Human Platelet Activation in Whole Blood in Vitro and in Vivo

    DTIC Science & Technology

    2007-11-02

    IX complex (the von Willebrand factor receptor) (12), thromboxane Bj generation (the stable metabolite of thromboxane A2) (13), platelet aggregate...6D1 (provided by Dr. Barry S. Coller, SUNY, Stony Brook) is directed against the von Willebrand factor receptor on the glycocalicin portion of the a...Fig 1, panel A) and, after a delay of approximately 20 seconds, downregulation of the platelet surface expression of GPIb (the von Willebrand factor

  6. Water Experiments Related To The "Von Karman Sodium" Dynamo Project

    NASA Astrophysics Data System (ADS)

    Marie, L.; Bourgoin, M.; Petrelis, F.; Roy, J.; Burguete, J.; Chiffaudel, A.; Daviaud, F.; Fauve, S.; Odier, P.; Pinton, J.-F.

    2002-07-01

    The purpose of the "Von Karman Sodium" (V.K.S.) experiment is to study the "Dynamo Effect," namely the spontaneous generation of magnetic field in a flow of electrically conducting fluid. The device has been built at CEA / Cadarache, in collaboration with CEA / Saclay, Ecole Normale Superieure de Lyon and Ecole Normale Superieure de Paris. It consists of a cylindrical vessel, filled with liquid Sodium, in which two coaxial rotating disks induce a Von-Karman type flow. Several experimental runs have taken place since June 2000. In order to optimize the V.K.S. set-up, a half-scale water prototype has also been built. It has allowed us to measure mean velocity profiles, as well as pressure fluctuations and mechanical power dissipation. We have observed that under certain circumstances the mean component of the turbulent flow can undergo a global bifurcation.

  7. Interpolatability distinguishes LOCC from separable von Neumann measurements

    SciTech Connect

    Childs, Andrew M.; Leung, Debbie; Mančinska, Laura; Ozols, Maris

    2013-11-15

    Local operations with classical communication (LOCC) and separable operations are two classes of quantum operations that play key roles in the study of quantum entanglement. Separable operations are strictly more powerful than LOCC, but no simple explanation of this phenomenon is known. We show that, in the case of von Neumann measurements, the ability to interpolate measurements is an operational principle that sets apart LOCC and separable operations.

  8. [Clemens Freiherr von Pirquet, developer of the concept of allergy].

    PubMed

    Bergmann, K C

    2006-07-20

    The pediatrician and scientist, Clemens Freiherr von Pirquet (1874-1929) was the first to coin the term "allergy". His experiments with Behring's serum, which he administered to sick children, led him to an awareness of an interaction between the human organism and pathogens. In his article published in the Müncher Medizinischen Wochenschrift in 1906, he laid the foundation stone for modern allergology.

  9. Baron von Zach's business relations with the Munich entrepreneur Joseph von Utzschneider (German Title: Geschäftsbeziehungen des Barons von Zach zu dem Münchner Unternehmer Joseph von Utzschneider)

    NASA Astrophysics Data System (ADS)

    Schneider, Ivo

    The relationship between the astronomer von Zach on the one side and the entrepreneur Joseph von Utzschneider and his partner Georg von Reichenbach on the other dates presumably from the year 1807 when Zach spent two months in Munich. Already in the same year Zach had ordered an instrument for himself and began to solicit business for the institute of Reichenbach, Utzschneider, and Liebherr, which was founded in 1804. One of the clients canvassed by Zach was the director of the observatory in Naples Zuccari. Zuccari had ordered the whole equipment for the new observatory from this institute in 1813. The instruments for Naples, which were completed in 1814, were sent accompanied by Reichenbach by land and sea to their destination where Reichenbach supervised their setup. At that time Reichenbach had separated from Utzschneider who kept the optical institute in Benediktbeuern with his new partner Joseph von Fraunhofer whereas Reichenbach became owner of the mathematical-mechanical institute in Munich. For personal and economical reasons Utzschneider began soon after to produce not only optical glass but also optical devices similar to those offered by Reichenbach. As soon as two institutes in Munich competed against each other on the market for sophisticated geodetical and astronomical instruments Zach sided with Utzschneider. Zach's main professional argument for this decision was that both competitors got the optical glass for their instruments from Utzschneider's optical institute in Benediktbeuern. This meant that Utzschneider had first choice and so the optical part of his instruments could be considered as better than that of Reichenbach`s instruments. Zach's role as an agent in Italy and France for the sale of products coming from Utzschneider's manufactories is highlighted by three of Zach's letters to Utzschneider from 1817 and 1818, two of which are reproduced here for the first time.

  10. Von Humboldt bis Einstein. Berlin als Weltzentrum der exakten Wissenschaften.

    NASA Astrophysics Data System (ADS)

    Meschkowski, H.

    Contents: 1. Die Anfänge. 2. Die Ära Dirichlet-Jacobi. 3. Der Ausbau der experimentellen Naturwissenschaften. 4. Alexander von Humboldt. 5. Berlin wird "Weltzentrum" der Mathematik. 6. Die Ära Helmholtz. 7. Neue Arbeitsweisen der Astronomie. 8. Chemie: Forschung und Industrie. 9. Max Planck. 10. Ins technische Zeitalter. 11. Zur Mathematik der zwanziger Jahre. 12. Albert Einstein. 13. Fortschritte der Grundlagenforschung. 14. Erwin Schrödinger: Physiker, Philosoph und Poet. 15. Zum Schluß.

  11. Johann Baptist von Schweitzer: the queer Marx loved to hate.

    PubMed

    Kennedy, H

    1995-01-01

    Despite his conviction on a morals charge involving a boy, the early German Social Democrat Johann Baptist von Schweitzer went on to have a successful political career. His life furnishes the context to present remarks by his political opponents Marx and Engels, which reveal their deep-seated homophobia. It is pointed out that this has been glossed over by the translations of the recently published Marx/Engels Collected Works. Some remarks on boy-love and anarchism are appended.

  12. Dr. von Braun In Front of a Display of Missiles

    NASA Technical Reports Server (NTRS)

    1960-01-01

    In this photo, Director of the US Army Ballistic Missile Agency (ABMA) Development Operations Division, Dr. Wernher von Braun, is standing before a display of Army missiles celebrating ABMA's Fourth Open House. The missiles in the background include (left to right) a satellite on a Juno II shroud with a Nike Ajax pointing left in front of a Jupiter missile. The Lacrosse is in front of the Juno II. The Nike Hercules points skyward in front of the Juno II and the Redstone.

  13. The British Interplanetary Society - Val Cleaver and Wernher von Braun

    NASA Astrophysics Data System (ADS)

    Willhite, I. P.

    This article is concerned with the early relationship between Wernher von Braun and the British Interplanetary Society (BIS). The BIS/Wernher von Braun/Val Cleaver correspondence files located here at the US Space & Rocket Center in Huntsville, Alabama are unparalleled. As one reads the stimulating comments between Cleaver and von Braun, the need to share their thoughts prevails. Following is an excerpt from one letter that whets ones appetite for more. 10 June 1951 Cleaver writes, “I'm so glad you enjoyed my last letter, and look forward to your promised further contribution to our discussion of the ethics of science in general and astronautics in particu- lar. As regards the one particular point on which you found yourself unable to hold your fire, I should say there are really two distinct issues at stake:. . .” This article attempts to represent the best of the letters as they goad each other on scientific principles, means to prevent wars, and other philosophic ideas.

  14. Operational Leadership: A Case of General Helmuth von Moltke (The Younger)

    DTIC Science & Technology

    2007-11-02

    makes his decision too late to have an impact. II. Historical Framework Helmuth Johannes Ludwig von Moltke, known as von Moltke (The Younger) to distin...T. N. Dupuy, A Genius for War (Englewood Cliffs, NJ: Prentis-Hall, Inc. 1977) 140. 1 Otto Friedrich , Blood and Iron: From Bismarck to Hitler the von...Press, 1996) 160. 1 Tuchman, The Guns of August, 73. 1 Friedrich , Blood and Iron, 229. 1 Holmes, “The Schlieffen Plan,” 13. ii

  15. Telecom 2-A (TC2A)

    NASA Technical Reports Server (NTRS)

    Dulac, J.; Latour, J.

    1991-01-01

    The DSN (Deep Space Network) mission support requirements for Telecom 2-A (TC2A) are summarized. The Telecom 2-A will provide high-speed data link applications, telephone, and television service between France and overseas territories. The mission objectives are outlined and the DSN support requirements are defined through the presentation of tables and narratives describing the spacecraft flight profile; DSN support coverage; frequency assignments; support parameters for telemetry, command and support systems; and tracking support responsibility.

  16. Spin torque oscillator neuroanalog of von Neumann's microwave computer.

    PubMed

    Hoppensteadt, Frank

    2015-10-01

    Frequency and phase of neural activity play important roles in the behaving brain. The emerging understanding of these roles has been informed by the design of analog devices that have been important to neuroscience, among them the neuroanalog computer developed by O. Schmitt and A. Hodgkin in the 1930s. Later J. von Neumann, in a search for high performance computing using microwaves, invented a logic machine based on crystal diodes that can perform logic functions including binary arithmetic. Described here is an embodiment of his machine using nano-magnetics. Electrical currents through point contacts on a ferromagnetic thin film can create oscillations in the magnetization of the film. Under natural conditions these properties of a ferromagnetic thin film may be described by a nonlinear Schrödinger equation for the film's magnetization. Radiating solutions of this system are referred to as spin waves, and communication within the film may be by spin waves or by directed graphs of electrical connections. It is shown here how to formulate a STO logic machine, and by computer simulation how this machine can perform several computations simultaneously using multiplexing of inputs, that this system can evaluate iterated logic functions, and that spin waves may communicate frequency, phase and binary information. Neural tissue and the Schmitt-Hodgkin, von Neumann and STO devices share a common bifurcation structure, although these systems operate on vastly different space and time scales; namely, all may exhibit Andronov-Hopf bifurcations. This suggests that neural circuits may be capable of the computational functionality as described by von Neumann.

  17. Otto von Guericke and 17th century cosmology

    NASA Astrophysics Data System (ADS)

    Knobloch, Eberhard

    Otto von Guericke's scientific method was based on reason and experimental science. His cosmology was embedded in theology and can be interpreted as a refutation of Descartes' worldview. He used Nicolaus Cusanus' theory of quantities in order to characterize space. The notion of space has to be distinguished from that of world or heaven. Forces play a crucial role in this respect described by Athanasius Kircher in his "Celestial Journey". Guericke read this work very diligently. In spite of some obvious similarities between Guericke's and Newton's scientific aims and methods there are crucial differences between the scientific convictions and results of these scholars.

  18. Nutzergerechte Entwicklung der Mensch-Maschine-Interaktion von Fahrerassistenzsystemen

    NASA Astrophysics Data System (ADS)

    König, Winfried

    Durch langjährige Forschungen bei Kfz-Herstellern, Zulieferfirmen und an Hochschulen sind umfangreiche, aber dennoch lückenhafte Erkenntnisse über das Zusammenspiel zwischen FAS und Nutzer gewonnen worden. In deutschen und internationalen Projekten wie z. B. PROMETHEUS, DRIVE, MOTIV, INVENT, RESPONSE und AKTIV haben sich Kfz-Hersteller, Zulieferfirmen, Hochschulen und weitere staatliche und private Forschungseinrichtungen zusammengefunden, um die vorwettbewerbliche Forschung für derartige Systeme voranzutreiben. Im folgenden Kapitel sollen einige der gewonnenen Kenntnisse dargelegt werden, um die Entwicklung des HMI von FAS zu erleichtern.

  19. Kernschmelze Der nachhaltige Einfluss von Nuklearwaffen auf Politik und Wirtschaft

    NASA Astrophysics Data System (ADS)

    Greiner, Bernd

    "Was sollen wir von einer Kultur halten, der die Ethik stets als wesentliches Element des menschlichen Lebens galt, die aber - außer in fachlicher oder spieltheoretischer Terminologie - nicht in der Lage war, über die Möglichkeit zu sprechen, nahezu alle Menschen zu töten?" Der Fragesteller gehört zu den berühmtesten Physikern des 20. Jahrhunderts und zu den nach wie vor Umstrittensten. über ihn wurde in den 1960er Jahren ein international viel beachtetes Theaterstück geschrieben, vor wenigen Jahren gar eine Oper.

  20. Dr. von Braun on the Mobility Test Article (MTA)

    NASA Technical Reports Server (NTRS)

    1966-01-01

    In this June 1966 photograph, Marshall Space Flight Center Director Dr. Wernher von Braun test-drives the Mobility Test Article (MTA), a developmental vehicle built by the Bendix Corporation to test lunar mobility vehicle concepts. The data provided by the MTA helped in designing the Lunar Roving Vehicle (LRV), developed under the direction of the MSFC. The LRV was designed to allow Apollo astronauts a greater range of mobility during lunar exploration missions. The LRVs were deployed during the last three Apollo missions; Apollo 15, Apollo 16, and Apollo 17.

  1. Dr. von Braun Driving the Mobility Test Article

    NASA Technical Reports Server (NTRS)

    1966-01-01

    In this June, 1966 photograph, Marshall Space Flight Center Director, Dr. Wernher von Braun test drives the Mobility Test Article (MTA), a developmental vehicle built by the Bendix Corporation to test lunar mobility concepts. The data provided by the MTA helped in designing the Lunar Roving Vehicle (LRV), developed under the direction of the Marshall Space Flight Center. The LRV was designed to allow Apollo astronauts a greater range during lunar exploration missions and served its purpose during the last three Apollo lunar missions in 1971 and 1972.

  2. The Fate of Western Civilization: G. H. von Wright's Reflections on Science, Technology, and Global Society

    ERIC Educational Resources Information Center

    Heikkero, Topi

    2004-01-01

    This article introduces the central ideas of G. H. von Wright's cultural philosophy concerning the techno-scientific form of life. Georg Henrik von Wright (1916-2003) was best known for his achievements in the field of modal logic and for his association with Ludwig Wittgenstein. However, his work also included a critical analysis of science and…

  3. 76 FR 36166 - Culturally Significant Objects Imported for Exhibition; Determinations: “Gabriel von Max: Be...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-21

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF STATE Culturally Significant Objects Imported for Exhibition; Determinations: ``Gabriel von Max: Be-Tailed Cousins... the exhibition ``Gabriel von Max: Be-Tailed Cousins and Phantasms of the Soul,'' imported from...

  4. An Alternative Perspective on von Winterfeldt et al.'s (1997) Test of Consequence Monotonicity

    ERIC Educational Resources Information Center

    Ho, Moon-Ho R.; Regenwetter, Michel; Niederee, Reinhard; Heyer, Dieter

    2005-01-01

    D. von Winterfeldt, N.-K. Chung, R. D. Luce, and Y. Cho (see record 1997-03378-008) provided several tests for consequence monotonicity of choice or judgment, using certainty equivalents of gambles. The authors reaxiomatized consequence monotonicity in a probabilistic framework and reanalyzed von Winterfeldt et al.'s main experiment via a…

  5. von Baer's law for the ages: lost and found principles of developmental evolution.

    PubMed

    Abzhanov, Arhat

    2013-12-01

    In 1828, Karl Ernst von Baer formulated a series of empirically defined rules, which became widely known as the 'Law of Development' or 'von Baer's law of embryology'. This was one the most significant attempts to define the principles that connected morphological complexity and embryonic development. Understanding this relation is central to both evolutionary biology and developmental genetics. Von Baer's ideas have been both a source of inspiration to generations of biologists and a target of continuous criticism over many years. With advances in multiple fields, including paleontology, cladistics, phylogenetics, genomics, and cell and developmental biology, it is now possible to examine carefully the significance of von Baer's law and its predictions. In this review, I argue that, 185 years after von Baer's law was first formulated, its main concepts after proper refurbishing remain surprisingly relevant in revealing the fundamentals of the evolution-development connection, and suggest that their explanation should become the focus of renewed research.

  6. Karl ernst von Baer's 'Uber Entwickelungsgeschichte der Thiere II' and its unpublished drawings.

    PubMed

    Tammiksaar, Erki; Brauckmann, Sabine

    2004-01-01

    In 1828 Karl Ernst von Baer (1792-1876) published his seminal Uber Entwickelungsgeschichte der Thiere. Beobachtung und Reflexion. In the preface he announced that a second volume with one copper plate would be finished 'in a few weeks'. However, it took nine years until the unfinished second volume was released, with four copperplates. In his 'Autobiography', von Baer did not clarify the reasons why he did not finish his research program of comparative embryology. The paper attempts to elucidate them, furnished by archival documents and von Baer's unpublished embryological drawings. Our sketch of a few figures will show that (1) von Baer searched for 'analogies' (homologies) as a unifying principle and (2) explained the mechanisms of embryogenesis by physiological reasoning (electromagnetism). The main objective is to show that technical problems in illustrating and conceptual difficulties impeded von Baer's ambitious research program.

  7. Von Braun Rocket Team at Fort Bliss, Texas

    NASA Technical Reports Server (NTRS)

    1940-01-01

    The German Rocket Team, also known as the Von Braun Rocket Team, poses for a group photograph at Fort Bliss, Texas. After World War II ended in 1945, Dr. Wernher von Braun led some 120 of his Peenemuende Colleagues, who developed the V-2 rocket for the German military during the War, to the United Sttes under a contract to the U.S. Army Corps as part of Operation Paperclip. During the following five years the team worked on high altitude firings of the captured V-2 rockets at the White Sands Missile Range in New Mexico, and a guided missile development unit at Fort Bliss, Texas. In April 1950, the group was transferred to the Army Ballistic Missile Agency (ABMA) at Redstone Arsenal in Huntsville, Alabama, and continued to work on the development of the guided missiles for the U.S. Army until transferring to a newly established field center of the National Aeronautic and Space Administration (NASA), George C. Marshall Space Flight Center (MSFC).

  8. The von Neumann model of measurement in quantum mechanics

    SciTech Connect

    Mello, Pier A.

    2014-01-08

    We describe how to obtain information on a quantum-mechanical system by coupling it to a probe and detecting some property of the latter, using a model introduced by von Neumann, which describes the interaction of the system proper with the probe in a dynamical way. We first discuss single measurements, where the system proper is coupled to one probe with arbitrary coupling strength. The goal is to obtain information on the system detecting the probe position. We find the reduced density operator of the system, and show how Lüders rule emerges as the limiting case of strong coupling. The von Neumann model is then generalized to two probes that interact successively with the system proper. Now we find information on the system by detecting the position-position and momentum-position correlations of the two probes. The so-called 'Wigner's formula' emerges in the strong-coupling limit, while 'Kirkwood's quasi-probability distribution' is found as the weak-coupling limit of the above formalism. We show that successive measurements can be used to develop a state-reconstruction scheme. Finally, we find a generalized transform of the state and the observables based on the notion of successive measurements.

  9. A visit paid to Jung by Alwine von Keller.

    PubMed

    Bernardini, Riccardo; Quaglino, Gian Piero; Romano, Augusto

    2011-04-01

    In the winter of 1943-1944, Jung had suffered a coronary thrombosis which almost cost him his life. During his illness, Jung experienced a series of visions, described in his Memories, Dreams, Reflections, which were also to influence significantly the development of his theoretical thinking. On 27(th) September 1944, Alwine von Keller (1878-1965) paid a visit to Jung, while he was still convalescing, in Zurich and documented her meeting with him in a series of notes, recently discovered, which testify to the fact that, at the time of their meeting, Jung was engaged in writing the 'Salt' chapter of Mysterium coniunctionis and investigating the alchemistic symbolism of the 'sea'. This theme seems to testify to a continuity of interests on Jung's part with the seminar he held at Eranos the previous year on the cartographic art of Opicinus de Canistris (1296-c.1352). With its addition of many unpublished details, Alwine von Keller's notes supplement the report which Jung made of his visions experienced during his sickness in MDR. In particular, these attest to the fact that Jung had attributed the terrible experience which he had endured to the problem of the conjunctio, which was confronting him from the theoretical point of view in his writing of Mysterium coniunctionis.

  10. Charakterisierung von Sulfotransferasen im Gastrointestinaltrakt von Mensch und Ratte und Aktivierung von Promutagenen in V79-Zellen, die eine intestinale Form (1B1) des Menschen und der Ratte exprimieren

    NASA Astrophysics Data System (ADS)

    Teubner, Wera

    2001-05-01

    Die Ausstattung der gastrointestinalen Mukosa des Menschen und der Ratte mit Sulfotransferasen wurde mit Hilfe von Immunodetektion und Enzymaktivitätsmessungen untersucht. In Proben aus Colon und Rektum von 39 Personen wurden die Formen h1A1, h1A3 und h1B1 identifiziert, wobei in einer weiteren Probe, die als einzige von einem an Colitis Ulcerosa erkrankten Patienten stammte, keine Sulfotransferasen nachgewiesen werden konnten. Bei der Immunblot-Analyse war das Expressionsmuster der einzelnen Formen in allen Proben ähnlich. In wenigen Proben waren die relativen Signalintensitäten der h1A1 und der h1B1 um die Hälfte erniedrigt. Der Gehalt von SULT an zytosolischem Protein zeigte einen bis zu 8 - 10fachen Unterschied, er betrug jedoch bei zwei Dritteln der Proben zwischen 0,15 und 0,3 (h1A1 und h1A3) bzw. 0,6 und 0,8 Promille (h1B1). Die Variation konnte nicht auf Alter, Geschlecht oder Krankheitsbild der Patienten zurückgeführt werden. Auch der für die allelischen Varianten der h1A1 beschriebene Effekt auf die Enzymaktiviät bzw. Stabilität konnte in der Menge an immunreaktivem Protein nicht in diesem Ausma detektiert werden. Die Allelhäufigkeit von h1A1*R und h1A1*H war gegenüber der gesunden Bevölkerung nicht verändert. In den sieben Proben aus dem Dünndarm (Coecum, viermal Ileum, Jejunum) konnten zusätzlich die Formen h1E1 und h2A1 identifiziert werden. Ein möglicherweise der Form h1C1 entsprechendes Protein wurde im Magen detektiert. Im Vergleich zum Menschen war die Expression in der Ratte stärker auf die Leber konzentriert. Während beim Menschen in allen untersuchten Abschnitten Sulfotransferasen in Mengen detektiert wurden, die in zwei Fällen (h1B1 und h1A3) sogar den Gehalt in der Leber überstiegen, beschränkte sich die Expression in der Ratte auf im Vergleich zur Leber geringe Mengen im Magen und Dickdarm. Nachgewiesen wurden die r1B1, r1A1 sowie eine nicht identifizierte Form von 35kD, bei der es sich vermutlich um die r1C2 handelt. Im

  11. [Ernst von der Porten : looking for facts before and after forced emigration].

    PubMed

    Goerig, M; Bruijn, L

    2014-10-01

    The Ernst von der Porten medal has been awarded for many years to exceptional personalities by the Alliance of German Anesthesiologists to honor the outstanding achievements of the physician Ernst von der Porten from Hamburg in the development of anesthesiology as an autonomous discipline Only recent access to hitherto inaccessible documents enabled the reconstruction of his final years. He was persecuted and excluded by the National Socialist (NS) regime due to his Jewish roots and finally forced to emigrate. Records revealed that even in the so-called safe exile, degrading treatment and humiliation continued for Ernst von der Porten and his family. He eventually evaded this situation by committing suicide.

  12. Alexander von Humboldt's perceptions of colonial Spanish America.

    PubMed

    Rebok, Sandra

    2009-01-01

    This study presents an in-depth analysis of Alexander von Humboldt's descriptions and critical comments on the colonial society of the different regions he visited during his well-known expedition through the Americas (1799-1804). The criticisms of colonialism that he expressed, reflecting his personal convictions, have already been the focal point of many studies, but Humboldt also was able to offer a more differentiated assessment through comparisons of regional and local traditions and developments. This essay focuses on his personal diaries, which offer many interesting comments on colonial societies. These considerations and impressions made during the expedition are of particular scholarly value since they were not subject to censorship of any kind.

  13. A Powerful Friendship: Theodore von Karman and Hugh L. Dryden

    NASA Technical Reports Server (NTRS)

    Gorn, Michael

    2003-01-01

    During their long personal friendship and professional association, Theodore von Karman (1882-1963) and Hugh L. Dryden (1898-1965) exercised a pivotal if somewhat elusive influence over American aeronautics and spaceflight. Both decisive figures in organizing scientists and engineers at home and abroad, both men of undisputed eminence in their technical fields, their range of contacts in government, academia, the armed forces, industry, and professional societies spanned the globe to an extent unparalleled then as now. Moreover, because they coordinated their activities closely, their combined influence far exceeded the sum of each one s individual contributions. This paper illustrates their personal origins as well as the foundations of their friendship, how their relationship became a professional alliance, and their joint impact on the world of aeronautics and astronautics during the twentieth century.

  14. Voluntarism in early psychology: the case of Hermann von Helmholtz.

    PubMed

    De Kock, Liesbet

    2014-05-01

    The failure to recognize the programmatic similarity between (post-)Kantian German philosophy and early psychology has impoverished psychology's historical self-understanding to a great extent. This article aims to contribute to recent efforts to overcome the gaps in the historiography of contemporary psychology, which are the result of an empiricist bias. To this end, we present an analysis of the way in which Hermann von Helmholtz's theory of perception resonates with Johann Gottlieb Fichte's Ego-doctrine. It will be argued that this indebtedness is particularly clear when focusing on the foundation of the differential awareness of subject and object in perception. In doing so, the widespread reception of Helmholtz's work as proto-positivist or strictly empiricist is challenged, in favor of the claim that important elements of his theorizing can only be understood properly against the background of Fichte's Ego-doctrine.

  15. Von Glaserfeld`s Radical Constructivism: A Critical Review

    NASA Astrophysics Data System (ADS)

    Hardy, Michael D.

    We explore Ernst von Glaserfelds radical constructivism, its criticisms, and our own thoughts on what it promises for the reform of science and mathematics teaching. Our investigation reveals that many criticisms of radical constructivism are unwarranted; nevertheless, in its current cognitivist form radical constructivism may be insufficient to empower teachers to overcome objectivist cultural traditions. Teachers need to be empowered with rich understandings of philosophies of science and mathematics that endorse relativist epistemologies; for without such they are unlikely to be prepared to reconstruct their pedagogical practices. More importantly, however, is a need for a powerful social epistemology to serve as a referent for regenerating the culture of science education. We recommend blending radical constructivism with Habermas theory of communicative action to provide science teachers with a moral imperative for adopting a constructivist epistemology.

  16. Stochastic resonance in a generalized Von Foerster population growth model

    SciTech Connect

    Lumi, N.; Mankin, R.

    2014-11-12

    The stochastic dynamics of a population growth model, similar to the Von Foerster model for human population, is studied. The influence of fluctuating environment on the carrying capacity is modeled as a multiplicative dichotomous noise. It is established that an interplay between nonlinearity and environmental fluctuations can cause single unidirectional discontinuous transitions of the mean population size versus the noise amplitude, i.e., an increase of noise amplitude can induce a jump from a state with a moderate number of individuals to that with a very large number, while by decreasing the noise amplitude an opposite transition cannot be effected. An analytical expression of the mean escape time for such transitions is found. Particularly, it is shown that the mean transition time exhibits a strong minimum at intermediate values of noise correlation time, i.e., the phenomenon of stochastic resonance occurs. Applications of the results in ecology are also discussed.

  17. [Reference relationships between human and animal in Hildegard von Bingen].

    PubMed

    Riethe, Peter

    2012-01-01

    In "De animalibus", the 7th book in the "Liber simplicis medicinae", Hildegard von Bingen describes the characteristics of four-footed land animals. Some of these have a special relationship with humans in that they embody moral qualities. An explanation for this is already given in the preface, which states that human intelligence recognizes these qualities, declaring that "You are this or that sort of creature". Since the relationship that animals have with nature shares a degree of similarity with that of man's, they can be regarded as symbolic representatives for particular human traits and characteristics. The article at hand presents Hildegard von Bingen's descriptions of the monkey, the lion, the bear, the rabbit, the dog, the cat, the wolf, the lynx, and the donkey. While the monkey just mimics man's behaviour and is imperfect in both settings, the lion embodies will power. The bear on the other hand stands for unbridled sexual desire, while in the rabbit the gentleness of a sheep is united with the bounce of a deer. The lynx is regarded as hedonistic, the donkey as stupid, and the wolf as surrounded by dangerous sylphs. In Hildegard's depictions, exotic and native animal species display rather extraordinary behavioural traits, and the medieval Christian world view of the author conveys unexpected relationships between humans and animals. In addition to empirical observation and experience, Hildegard also relies on folkloristic beliefs and magical practices related to explanatory models of her time. She allows largely unknown sources into her animal lore but never strays from her ultimate goal of having it serve to instruct people. In doing so, Hildegard removed herself far from the common tradition of medieval animal portraits.

  18. Dynamics of Diffusion Flames in von Karman Swirling Flows Studied

    NASA Technical Reports Server (NTRS)

    Nayagam, Vedha; Williams, Forman A.

    2002-01-01

    Von Karman swirling flow is generated by the viscous pumping action of a solid disk spinning in a quiescent fluid media. When this spinning disk is ignited in an oxidizing environment, a flat diffusion flame is established adjacent to the disk, embedded in the boundary layer (see the preceding illustration). For this geometry, the conservation equations reduce to a system of ordinary differential equations, enabling researchers to carry out detailed theoretical models to study the effects of varying strain on the dynamics of diffusion flames. Experimentally, the spinning disk burner provides an ideal configuration to precisely control the strain rates over a wide range. Our original motivation at the NASA Glenn Research Center to study these flames arose from a need to understand the flammability characteristics of solid fuels in microgravity where slow, subbuoyant flows can exist, producing very small strain rates. In a recent work (ref. 1), we showed that the flammability boundaries are wider and the minimum oxygen index (below which flames cannot be sustained) is lower for the von Karman flow configuration in comparison to a stagnation-point flow. Adding a small forced convection to the swirling flow pushes the flame into regions of higher strain and, thereby, decreases the range of flammable strain rates. Experiments using downward facing, polymethylmethacrylate (PMMA) disks spinning in air revealed that, close to the extinction boundaries, the flat diffusion flame breaks up into rotating spiral flames (refs. 2 and 3). Remarkably, the dynamics of these spiral flame edges exhibit a number of similarities to spirals observed in biological systems, such as the electric pulses in cardiac muscles and the aggregation of slime-mold amoeba. The tail of the spiral rotates rigidly while the tip executes a compound, meandering motion sometimes observed in Belousov-Zhabotinskii reactions.

  19. John von Neumann and Klaus Fuchs: an Unlikely Collaboration

    NASA Astrophysics Data System (ADS)

    Bernstein, Jeremy

    2010-03-01

    I discuss the origin of the idea of making a fusion (hydrogen) bomb and the physics involved in it, and then turn to the design proposed for one by the unlikely collaborators John von Neumann and Klaus Fuchs in a patent application they filed at Los Alamos in May 1946, which Fuchs passed on to the Russians in March 1948, and which with substantial modifications was tested on the island of Eberiru on the Eniwetok atoll in the South Pacific on May 8, 1951. This test showed that the fusion of deuterium and tritium nuclei could be ignited, but that the ignition would not propagate because the heat produced was rapidly radiated away. Meanwhile, Stanislaw Ulam and C.J. Everett had shown that Edward Teller’s Classical Super could not work, and at the end of December 1950, Ulam had conceived the idea of super compression, using the energy of a fission bomb to compress the fusion fuel to such a high density that it would be opaque to the radiation produced. Once Teller understood this, he invented a greatly improved, new method of compression using radiation, which then became the heart of the Ulam-Teller bomb design, which was tested, also in the South Pacific, on November 1, 1952. The Russians have freely acknowledged that Fuchs gave them the fission bomb, but they have insisted that no one gave them the fusion bomb, which grew out of design involving a fission bomb surrounded by alternating layers of fusion and fission fuels, and which they tested on November 22, 1955. Part of the irony of this story is that neither the American nor the Russian hydrogen-bomb programs made any use of the brilliant design that von Neumann and Fuchs had conceived as early as 1946, which could have changed the entire course of development of both programs.

  20. Dr. Wernher Von Braun leads a tour of the S-IC checkout area.

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Dr. Eberhard Rees, Charles Schultze, James Webb, Elmer Staats, Comptroller General of the United States, and Dr. Wernher Von Braun tour the S-IC checkout area in the Marshall Space Flight Center quality lab.

  1. Somatostatin receptor expression on von Hippel-Lindau-associated hemangioblastomas offers novel therapeutic target

    PubMed Central

    Sizdahkhani, Saman; Feldman, Michael J.; Piazza, Martin G.; Ksendzovsky, Alexander; Edwards, Nancy A.; Ray-Chaudhury, Abhik; Maric, Dragan; Merrill, Marsha J.; Pacak, Karel; Zhuang, Zhengping; Chittiboina, Prashant

    2017-01-01

    Von Hippel-Lindau (VHL)-associated hemangioblastomas (VHL-HB) arise in the central nervous system (CNS), and are a leading cause of morbidity and mortality in VHL disease. Currently, surgical resection is the most effective way to manage symptomatic VHL-HBs. Surgically unresectable VHL-HBs or those in frail patients are challenging problems. Therapies targeting oncologic and vascular endothelial growth factor (VEGF) pathways have failed to demonstrate tumor control. Our experience and previous reports on VHL-HB avidity to somatostatin analogues suggested somatostatin receptor (SSTR) expression in VHL-HBs, offering an alternative therapeutic strategy. We explored this possibility by demonstrating consistent histologic expression of SSTR1, 2a, 4, and 5 in VHL-HBs. We found that somatostatin analogue octreotide induces apoptosis in VHL-HB stromal cells in a dose-dependent fashion by BAX – caspase-3 pathway unrelated to canonical VHL pathway. When administered to a patient with unresectable symptomatic suprasellar hemangioblastoma, octreotide resulted in tumor volume reduction, symptom stabilization, and tumor cytopenia on repeat 68Ga-DOTA-TATE positron emission tomography (PET) within 6 months, suggesting tumor infarction. We conclude that VHL-HBs harbor multiple SSTR subtypes that offer actionable chemo-therapeutic strategy for management of symptomatic, unresectable tumors by somatostatin analogue therapy. PMID:28094316

  2. Somatostatin receptor expression on von Hippel-Lindau-associated hemangioblastomas offers novel therapeutic target.

    PubMed

    Sizdahkhani, Saman; Feldman, Michael J; Piazza, Martin G; Ksendzovsky, Alexander; Edwards, Nancy A; Ray-Chaudhury, Abhik; Maric, Dragan; Merrill, Marsha J; Pacak, Karel; Zhuang, Zhengping; Chittiboina, Prashant

    2017-01-17

    Von Hippel-Lindau (VHL)-associated hemangioblastomas (VHL-HB) arise in the central nervous system (CNS), and are a leading cause of morbidity and mortality in VHL disease. Currently, surgical resection is the most effective way to manage symptomatic VHL-HBs. Surgically unresectable VHL-HBs or those in frail patients are challenging problems. Therapies targeting oncologic and vascular endothelial growth factor (VEGF) pathways have failed to demonstrate tumor control. Our experience and previous reports on VHL-HB avidity to somatostatin analogues suggested somatostatin receptor (SSTR) expression in VHL-HBs, offering an alternative therapeutic strategy. We explored this possibility by demonstrating consistent histologic expression of SSTR1, 2a, 4, and 5 in VHL-HBs. We found that somatostatin analogue octreotide induces apoptosis in VHL-HB stromal cells in a dose-dependent fashion by BAX - caspase-3 pathway unrelated to canonical VHL pathway. When administered to a patient with unresectable symptomatic suprasellar hemangioblastoma, octreotide resulted in tumor volume reduction, symptom stabilization, and tumor cytopenia on repeat (68)Ga-DOTA-TATE positron emission tomography (PET) within 6 months, suggesting tumor infarction. We conclude that VHL-HBs harbor multiple SSTR subtypes that offer actionable chemo-therapeutic strategy for management of symptomatic, unresectable tumors by somatostatin analogue therapy.

  3. Dr. von Braun with Gen. Ostrander, Dr. Rees, and Gen. Barclay

    NASA Technical Reports Server (NTRS)

    1959-01-01

    In this 1959 photo, taken at Cape Canaveral, Florida, Dr. von Braun (2nd from left) Director of the U.S. Army Ballistic Missile Agency's (ABMA) Development Operations Division, is shown conferring with Air Force Major General Donald R. Ostrander (left), on assignment at NASA as launch vehicle director; Dr. Eberhard Rees, deputy to Dr. von Braun, and Army Brigadier General John Barclay, commander of the ABMA.

  4. Markov property and strong additivity of von Neumann entropy for graded quantum systems

    SciTech Connect

    Moriya, Hajime

    2006-03-15

    The quantum Markov property is equivalent to the strong additivity of von Neumann entropy for graded quantum systems. The additivity of von Neumann entropy for bipartite graded systems implies the statistical independence of states. However, the structure of Markov states for graded systems is different from that for tensor-product systems which have trivial grading. For three-composed graded systems we have U(1)-gauge invariant Markov states whose restriction to the marginal pair of subsystems is nonseparable.

  5. von Neumann measurement-related matrices and the nullity condition for quantum correlation

    NASA Astrophysics Data System (ADS)

    Zhao, MingJing; Ma, Teng; Zhang, TingGui; Fei, Shao-Ming

    2016-12-01

    We study von Neumann measurement-related matrices, and the nullity condition of quantum correlation. We investigate the properties of these matrices that are related to a von Neumann measurement. It is shown that these ( m 2 - 1) × ( m 2 - 1) matrices are idempotent, and have rank m - 1. These properties give rise to necessary conditions for the nullity of quantum correlations in bipartite systems. Finally, as an example we discuss quantum correlation in Bell diagonal states.

  6. Fibroblast growth factor-10 signals development of von Brunn's nests in the exstrophic bladder.

    PubMed

    Eastman, Rocky; Leaf, Elizabeth M; Zhang, Dianzhong; True, Lawrence D; Sweet, Robert M; Seidel, Kristy; Siebert, Joseph R; Grady, Richard; Mitchell, Michael E; Bassuk, James A

    2010-11-01

    von Brunn's nests have long been recognized as precursors of benign lesions of the urinary bladder mucosa. We report here that von Brunn's nests are especially prevalent in the exstrophic bladder, a birth defect that predisposes the patient to formation of bladder cancer. Cells of von Brunn's nest were found to coalesce into a stratified, polarized epithelium which surrounds itself with a capsule-like structure rich in types I, III, and IV collagen. Histocytochemical analysis and keratin profiling demonstrated that nested cells exhibited a phenotype similar, but not identical, to that of urothelial cells of transitional epithelium. Immunostaining and in situ hybridization analysis of exstrophic tissue demonstrated that the FGF-10 receptor is synthesized and retained by cells of von Brunn's nest. In contrast, FGF-10 is synthesized and secreted by mesenchymal fibroblasts via a paracrine pathway that targets basal epithelial cells of von Brunn's nests. Small clusters of 10pRp cells, positive for both FGF-10 and its receptor, were observed both proximal to and inside blood vessels in the lamina propria. The collective evidence points to a mechanism where von Brunn's nests develop under the control of the FGF-10 signal transduction system and suggests that 10pRp cells may be the original source of nested cells.

  7. Ludwig von Bertalanffy's Organismic View on the Theory of Evolution

    PubMed Central

    Drack, Manfred

    2015-01-01

    Ludwig von Bertalanffy was a key figure in the advancement of theoretical biology. His early considerations already led him to recognize the necessity of considering the organism as a system, as an organization of parts and processes. He termed the resulting research program organismic biology, which he extended to all basic questions of biology and almost all areas of biology, hence also to the theory of evolution. This article begins by outlining the rather unknown (because often written in German) research of Bertalanffy in the field of theoretical biology. The basics of the organismic approach are then described. This is followed by Bertalanffy's considerations on the theory of evolution, in which he used methods from theoretical biology and then introduced his own, organismic, view on evolution, leading to the demand for finding laws of evolution. Finally, his view on the concept of homology is presented. J. Exp. Zool. (Mol. Dev. Evol.) 324B: 77–90, 2015. © 2015 The Authors. Journal of Experimental Zoology Part B: Molecular and Developmental Evolution published by Wiley Periodicals, Inc. PMID:25727202

  8. THE FINE STRUCTURE OF VON EBNER'S GLAND OF THE RAT

    PubMed Central

    Hand, Arthur R.

    1970-01-01

    The fine structure of von Ebner's gland was studied in untreated rats and rats stimulated to secrete by fasting-refeeding or injection of pilocarpine. Cytological features were similar to those reported for pancreas and parotid gland. Abundant granular endoplasmic reticulum filled the basal portion of the cell, a well-developed Golgi complex was located in the vicinity of the nucleus, and the apical portion of the cell was filled with dense secretory granules. Dense heterogeneous bodies resembling lysosomes were closely associated with the Golgi complex. Coated vesicles were seen in the Golgi region and also in continuity with the cell membrane. Granule discharge occurred by fusion of the granule membrane with the cell membrane at the secretory surface. Successive fusion of adjacent granules to the previously fused granule formed a connected string of granules in the apical cytoplasm. Myoepithelial cells were present within the basement membrane, and nerve processes were seen adjacent to acinar and myoepithelial cells. Duct cells resembled the intercalated duct cells of the major salivary glands. PMID:5411078

  9. [Hermann von Helmholtz and Carl Stumpf on consonance and dissonance].

    PubMed

    Kursell, Julia

    2008-06-01

    The article juxtaposes Hermann von Helmholtz's work in the experimental physiology of hearing and Carl Stumpf's tone psychology, focusing on the problem of consonance and dissonance in music. It argues that the experimental set-up plays a major role in the approaches to hearing of both Helmholtz and Stumpf, shaping their redefinition of the musical concepts of consonance and dissonance. Helmholtz, however, explains dissonance as resulting from the beats that are heard when sound waves interfere, while Stumpf explains consonance from the fusion (Verschmelzung) of sounds, noting that two tones, depending on their distance cannot always be recognized as two but are heard as one single tone. Helmholtz's definition of dissonance eventually threatens his own theory of hearing, which is based on the mechanical principle of resonance and considers sound to be composed of sinusoidal waves. Both the physical and the mathematical tools he uses cannot easily be brought into accordance with his experimental findings on beats, which ask for a discrimination of fast changes in intensity. Dissonance thus becomes "unrecomendable" for Helmholtz, because it overstrains the ear. Stumpf's research, in contrast, has its point of departure in the historically given set of intervals and tries to find a principle that would explain this choice. His tests with experimental subjects who have no conscious knowledge of musical harmony and prove incapable to follow or reproduce music reveals to him a difference between the unity and multiplicity of tones.

  10. [Hans von Hattingberg between psychoanalysis and National Socialism].

    PubMed

    Keifenheim, Katharina Eva

    2011-01-01

    Hans von Hattingberg (1879-1944) worked as a neurologist and psychoanalyst in Munich and Berlin from about 1910 to 1944. He was a prolific writer, but met with increasing disapproval from Freud and his circle. An advocate of the union of different psychotherapeutic schools, he was initially a marginal figure in the professional field. With Hitler's rise to power his career prospered: He was offered the position of a lecturer for psychotherapy and became head of the research department at the "Göring Institute". He came to prominence with his writings on the "Neue deutsche Seelenheilkunde" despite the fact that this was never his preferred topic. The main themes of his publications were marriage, love and female emancipation. Those works contain only little of the standard Nazi ideology of the time. Not only was Hattingberg never a member of the NSDAP (the ruling party), but in some respects he could conceivably be considered a member of the resistance. The article outlines the most important stages of Hattingberg's life and focuses on the question of how he positioned himself after 1933, when it became vital for him to reconcile psychoanalysis and National Socialism.

  11. Emperor Ashoka: Did he suffer from von Recklinghausen's diseases?

    PubMed Central

    Wig, N. N.; Sharma, Sheetal

    2015-01-01

    Emperor Ashoka is widely regarded as one of the greatest rulers of India. This paper mainly deals with his medical condition as recorded in the Buddhist texts of Sri Lanka as well as in the Buddhist texts of North India and Nepal. These sources mention his skin disorder which is described as very rough and unpleasant to touch. He is also known to have episodes of loss of consciousness at various times in his life. One of the earliest representations of Ashoka, about 100 years after his death at one of the gates of Sanchi Stupa, shows Ashoka fainting when visiting the Bodhi tree and being held by his queens. In this sculpture, Emperor Ashoka is shown as a man of short height, large head and a paunchy abdomen. In this paper, it is speculated that Emperor Ashoka was probably suffering from von Recklinghausen disease (Neurofibromatosis Type 1), which could explain his skin condition, episodes of loss of consciousness (probably epilepsy) and other bodily deformities. PMID:25657467

  12. Von recklinghausen disease: one patient – various problems

    PubMed Central

    Miziołek, B; Brzezińska-Wcisło, L

    2016-01-01

    Abstract von Recklinghausen disease (vRD), more widely known as neurofibromatosis type 1, belongs to a group of genetic disorders and it is considered to be the most common genodermatosis. The disease has an autosomal dominant pattern of inheritance that involves mutations within the NF1 gene located on chromosome 17 in locus q11.2. The product of the NF1 gene is neurofibromin and the protein is well known to be a tumor suppressor factor. This counteracts possible overactivity of RAS (protein)/MAPK (mitogen-activated protein kinase) and RAS/PI3K/AKT/mTOR (phoshatydyloinositol-3-kinase/V-akt murine thy-moma viral oncogene homologue/mammalian target of rapamycin) signaling transduction pathways, preventing from uncontrolled cell proliferation and subsequent tumor formation. A loss of proper functioning of this protein leads to a development of vRD; however, a large variability in a phenotype of the disease and the onset of cutaneous findings, not necessarily in childhood, may provide a clinical diagnosis of the disease late in adulthood. We present a 52-year-old male in whom the diagnosis of vRD was proposed in the sixth decade of life, despite of multiple nodular lesions disseminated over the skin of the whole body and different neurological disturbances, not considered for a long time as manifestations of genodermatosis. PMID:27785414

  13. Magnetohydrodynamics measurements in the von Karman sodium experiment

    NASA Astrophysics Data System (ADS)

    Bourgoin, Mickael; Marie, Louis; Petrelis, Francois; Gasquet, Cecile; Guigon, Alain; Luciani, Jean-Baptiste; Moulin, Marc; Namer, Frederic; Burguete, Javier; Chiffaudel, Arnaud; Fauve, Stephan; Odier, Philippe

    2002-09-01

    We study the magnetic induction in a confined swirling flow of liquid sodium, at integral magnetic Reynolds numbers up to 50. More precisely, we measure in situ the magnetic field induced by the flow motion in the presence of a weak external field. Because of the very small value of the magnetic Prandtl number of all liquid metals, flows with even modest Rm are strongly turbulent. Large mean induction effects are observed over a fluctuating background. As expected from the von Karman flow geometry, the induction is strongly anisotropic. The main contributions are the generation of an azimuthal induced field when the applied field is in the axial direction (an Omega effect) and the generation of axial induced field when the applied field is the transverse direction (as in a large scale alpha effect). Strong fluctuations of the induced field, due to the flow nonstationarity, occur over time scales slower than the flow forcing frequency. In the spectral domain, they display a f-1 spectral slope. At smaller scales (and larger frequencies) the turbulent fluctuations are in agreement with a Kolmogorov modeling of passive vector dynamics.

  14. Modellbasierte Segmentierung von differenzierten Lymphknoten in CT-Daten

    NASA Astrophysics Data System (ADS)

    Dornheim, Lars; Dornheim, Jana

    Für die computerbasierte Diagnoseunterstützung bei Tumorerkrankungen ist Wissen über Lage, Ausdehnung und Art der Lymphknoten für die TNM-Klassifikation nötig. Für die computergestütze Planung nachfolgender Eingriffe wie der Hals-Lymphknoten-Ausräumung, ist dieses Wissen ebenfalls von Bedeutung. Deshalb ist ein effizientes und exaktes Segmentierungsverfahren für Lymphknoten in CT-Datensätzen erforderlich, das besonders auch mit pathologisch veränderten Lymphknoten zurechtkommt. Basierend auf früheren Arbeiten präsentieren wir in dieser Arbeit ein deutlich weiterentwickeltes, modellbasiertes Segmentierungsverfahren für Lymphknoten in CT-Datensätzen, mit dem nun besonders auch vergrößerte sowie nekrotische Lymphknoten adressiert werden. Unser Verfahren wurde an 21 Lymphknoten aus 5 CT-Datensätzen getestet, darunter mehrere vergrößerte und nekrotische. Die Ergebnisse liegen im Bereich der Inter-Personen-Varianz und verbessern die Ergebnisse früherer Arbeiten noch einmal spürbar.

  15. Bifurcation analysis of an infinite array of von Karman Streets

    NASA Astrophysics Data System (ADS)

    Ghaemi Oskouei, Babak; Kanso, Eva; Newton, Paul K.

    2008-11-01

    This research investigates the behavior of an infinite array of (inverse) von Karman streets. Primary motivation is to model the wake dynamics in large fish schools. Ignoring the fish we focus on the dynamic interaction of multiple wakes. In particular, we investigate the problem of fluid transport between adjacent vortex streets for its relevance to understanding the transport of oxygen and nutrients to inner fish in large schools as well as understanding flow barriers to passive locomotion. We prove that the configuration of vortices is in relative equilibrium, meaning that the streamline pattern remains steady in the frame moving with vortices. We look at the topology of these streamline patterns plotted in the moving frame which lends insight to fluid transport through the mid-wake region. Fluid is advected along different paths depending on the distance separating two adjacent streets. When the streets are far apart, the dynamics is decoupled and fluid is transported globally between two adjacent streets. When the streets get closer to each other, the number of streets that enter into partnership in transporting fluid among themselves increases. This observation motivates a bifurcation analysis which links the distance between streets to the maximum number of streets transporting fluid among themselves.

  16. Darwin the geologist: Between Lyell and von Buch.

    PubMed

    Gohau, Gabriel

    2010-02-01

    Upon returning from his voyage on the Beagle, Darwin prepared reports of his geological observations. Together, these reveal Darwin's approach to reasoning about geology. Darwin argued that successive terraces prove a very gradual elevation of the coast that lagoon islands show a reciprocal sinking of the oceanic floor. Hence, Darwin reinforced Lyell's uniformitarian, or steady state theory. Unlike lagoon islands, the movement of erratic boulders onto the plains is evidence of forces, which do not now exist. Darwin and Lyell attributed this movement to floating icebergs. However, mountain formation remained difficult for them to explain with reference to contemporary causes. Lyell discovered uplifts in Scandinavia, which resulted from epirogenesis, whereas mountain formation is an orogenesis, which involves both folding and uplift. Darwin was more impressed by uplift than by folds. However, when in Cordillera he saw strata overturned by masses of injected rock, proving successive periods of violence, Darwin took a position, which was closer to the plutonic theories of von Buch and Humboldt than it was to Lyell's uniformitarian views.

  17. [Heinrich von Kleist--crisis and creative overcoming].

    PubMed

    Schlimme, J

    2001-07-01

    Heinrich von Kleist's life was shaken repeatedly by negative life-events, finally he committed suicide in his last life-crisis (1811). His work was mostly understood as descriptions of negative life-events and failed-being. In this article it will be shown that in at least two "crises" Kleist's work can be understood as a creative overcome of those. Kleist shows in his "Essay to Find a Sure Way to Happiness" (1799) his way of solving his "Soldier-Crisis" (1798), a depressive episode. In "The Broken Jug" (1802 - 1805) he shows the implications of a philosophical problem experienced in his "Kant-Crisis" (1801) and offers chances to overcome this particular crisis, which still seems to be an actual problem of ourselves. Though his crises must be understood as depressive episodes, at least the "Kant-Crisis" with its connections to philosophical and artistical matters seems to be more complicated than a simple depressive syndrome. Kleist formulates his basic life-experience, to be repeatedly shaken by "crises" respectively depressive episodes and the necessity to overcome each in a new way of living.

  18. [Carl Friedrich von Weizsäcker - physicist and philosopher].

    PubMed

    Drieschner, Michael

    2014-01-01

    The subject of this paper is the philosopher Carl Friedrich von weizsäcker, especially under the aspect of the relation between physics and philosophy in his works. The decisive role of time in physics as well as in philosophy is described, and thereof is derived the comprehension of probability as a predicted relative frequency. Consequently quantum mechanics is interpreted as a theory of probability that uses "quantum logic" instead of classical propositional logic that is used in "normal" probability. The philosophical fruit of that is the interpretation of potentiality as the modality of the future. Weizsäcker's proposals for a justification of physics a priori are dealt with as well as his approach to a theory of "ur-objects", which are atoms in the strictest sense: q-bits.--Questions of Weizsäcker's personality are addressed: His role in the development of the nuclear reactor and atomic bomb in Nazi time, his enthusiasm and his religiousness as well as his efforts towards world peace.

  19. Von Hippel-Lindau disease involving pancreas and biliary system

    PubMed Central

    Zhi, Xu-Ting; Bo, Qi-Yu; Zhao, Feng; Sun, Dong; Li, Tao

    2017-01-01

    Abstract Rationale: Von Hippel-Lindau (VHL) disease is a rare inherited, autosomal-dominant syndrome caused by heterozygous germline mutations in the VHL gene. VHL patients are prone to develop benign and malignant tumors and cysts in multiple organ systems involving kidneys, pancreas and central nervous system (CNS). The varied and complex clinical manifestations and radiological findings of VHL are of interest. Patient concerns: We report a 38-year-old woman with a ten-year history of VHL disease involving both pancreas and biliary system. To the best of our knowledge, direct involvement of the biliary system in VHL disease has never been reported. Diagnoses: The diagnosis was established via computed tomography scan and was confirmed by genetic testing. Interventions: The patient chose to receive conservative treatment and was followed up by magnetic resonance cholangiopancreatography and magnetic resonance imaging examination. Outcomes: Renal angiomas and cysts were found during follow-up and there were no evidence of malignant change of the pancreas and biliary system. Lessons: We described the first case of VHL-associated choledochal cysts and may present new visceral manifestations of VHL disease. Gastroenterologists should be aware of the clinical presentations of this rare disease for early detection of its life-threatening manifestations. PMID:28072736

  20. SCN2A encephalopathy

    PubMed Central

    Howell, Katherine B.; McMahon, Jacinta M.; Carvill, Gemma L.; Tambunan, Dimira; Mackay, Mark T.; Rodriguez-Casero, Victoria; Webster, Richard; Clark, Damian; Freeman, Jeremy L.; Calvert, Sophie; Olson, Heather E.; Mandelstam, Simone; Poduri, Annapurna; Mefford, Heather C.; Harvey, A. Simon

    2015-01-01

    Objective: De novo SCN2A mutations have recently been associated with severe infantile-onset epilepsies. Herein, we define the phenotypic spectrum of SCN2A encephalopathy. Methods: Twelve patients with an SCN2A epileptic encephalopathy underwent electroclinical phenotyping. Results: Patients were aged 0.7 to 22 years; 3 were deceased. Seizures commenced on day 1–4 in 8, week 2–6 in 2, and after 1 year in 2. Characteristic features included clusters of brief focal seizures with multiple hourly (9 patients), multiple daily (2), or multiple weekly (1) seizures, peaking at maximal frequency within 3 months of onset. Multifocal interictal epileptiform discharges were seen in all. Three of 12 patients had infantile spasms. The epileptic syndrome at presentation was epilepsy of infancy with migrating focal seizures (EIMFS) in 7 and Ohtahara syndrome in 2. Nine patients had improved seizure control with sodium channel blockers including supratherapeutic or high therapeutic phenytoin levels in 5. Eight had severe to profound developmental impairment. Other features included movement disorders (10), axial hypotonia (11) with intermittent or persistent appendicular spasticity, early handedness, and severe gastrointestinal symptoms. Mutations arose de novo in 11 patients; paternal DNA was unavailable in one. Conclusions: Review of our 12 and 34 other reported cases of SCN2A encephalopathy suggests 3 phenotypes: n