Von Willebrand's disease: case report and review of literature.

PubMed

Echahdi, Hanae; El Hasbaoui, Brahim; El Khorassani, Mohamed; Agadr, Aomar; Khattab, Mohamed

2017-01-01

Von Willebrand Disease (VWD) is the most common human inherited bleeding disorder due to a defect of Von Willebrand Factor (VWF), which 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 50IU/dL). Von willebrand factor is a complex multimeric protein with two functions: it forms a bridge between the platelets and areas of vascular damage and it binds to and stabilizes factor VIII, which is necessary for the clotting cascade. By taking a clinical history of bleeding (mucocutaneous bleeding symptoms suggestive of a primary haemostatic disorder, a quantitative or qualitative abnormality of VWF is possible) it is important to think about VWD and to make the appropriate diagnosis. If the VWD is suspected diagnostic tests should include an activated partial thromboplastin time, bleeding time, factor VIII: C Ristocetin cofactor and vWF antigen. Additional testing of ristocetin induced plattlet adhesion (RIPA) the multimeric structure and collagen binding test and genanalysis allow diagnosing the different types of von. Willebrand Disease. The treatment of choice in mild forms is the synthetic agent desmopressin. In patients with severe type 1, type 2B, 2N and type 3 or in people who do not response to desmopressin, the appropriate treatment is a factor VIII concentrate that is rich of VWF. We report a case of infant in 27-month-old boy who had been referred due to haemorrhagic shock. His birth histories, his familie's social history and developmental milestones were unremarkable. He was born at full term with no antenatal or perinatal complications. Prior to

[Homocysteine and von Willebrand factor in chronic alcoholism].

PubMed

Koriakin, A M; Epifantseva, N N; Dadyka, I V; Gorbatovskiĭ, Ia A

2010-04-01

The levels of homocysteine (HC) and von Willebrand factor (VWF) as cardiovascular risk factors were studied in patients with Stage II chronic alcoholism. Forty-one men with Stage II chronic alcoholism without clinical signs of somatic and infectious diseases were examined. Their median age was 37 (range 32-40) years; the alcoholization period was 12 (range 8-17) years. Plasma HC and VWF (amount and activity) levels were determined. In 63.4% of chronic alcoholic patients, HC levels was twice as high as in the controls; in 80.6%, both the content and activity of VWF were increased. There was no correlation between the levels of HC and VWF. Vascular endothelial damage concurrent with hyperhomocysteinemia increases a cardiovascular risk in patients with Stage II chronic alcoholism.

Of von Willebrand factor and platelets.

PubMed

Bryckaert, Marijke; Rosa, Jean-Philippe; Denis, Cécile V; Lenting, Peter J

2015-01-01

Hemostasis and pathological thrombus formation are dynamic processes that require multiple adhesive receptor-ligand interactions, with blood platelets at the heart of such events. Many studies have contributed to shed light on the importance of von Willebrand factor (VWF) interaction with its platelet receptors, glycoprotein (GP) Ib-IX-V and αIIbβ3 integrin, in promoting primary platelet adhesion and aggregation following vessel injury. This review will recapitulate our current knowledge on the subject from the rheological aspect to the spatio-temporal development of thrombus formation. We will also discuss the signaling events generated by VWF/GPIb-IX-V interaction, leading to platelet activation. Additionally, we will review the growing body of evidence gathered from the recent development of pathological mouse models suggesting that VWF binding to GPIb-IX-V is a promising target in arterial and venous pathological thrombosis. Finally, the pathological aspects of VWF and its impact on platelets will be addressed.

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

Profile of von Willebrand factor antigen and von Willebrand factor propeptide in an overall TIA and ischaemic stroke population and amongst subtypes.

PubMed

Tobin, W O; Kinsella, J A; Kavanagh, G F; O'Donnell, J S; McGrath, R T; Tierney, S; Egan, B; Feeley, T M; Coughlan, T; Collins, D R; O'Neill, D; Murphy, Sjx; Lim, S J; Murphy, R P; McCabe, Djh

2017-04-15

Von Willebrand factor propeptide (VWF:Ag II) is proposed to be a more sensitive marker of acute endothelial activation than von Willebrand factor antigen (VWF:Ag). Simultaneous data on VWF:Ag and VWF:Ag II profiles are very limited following TIA and ischaemic stroke. In this prospective, observational, case-control study, plasma VWF:Ag and VWF:Ag II levels were quantified in 164 patients≤4weeks of TIA or ischaemic stroke (baseline), and then ≥14days (14d) and ≥90days (90d) later, and compared with those from 27 healthy controls. TIA and stroke subtyping was performed according to the TOAST classification. The relationship between VWF:Ag and VWF:Ag II levels and platelet activation status was assessed. 'Unadjusted' VWF:Ag and VWF:Ag II levels were higher in patients at baseline, 14d and 90d than in controls (p≤0.03). VWF:Ag levels remained higher in patients than controls at baseline (p≤0.03), but not at 14d or 90d after controlling for differences in age or hypertension, and were higher in patients at baseline and 90d after controlling for smoking status (p≤0.04). 'Adjusted' VWF:Ag II levels were not higher in patients than controls after controlling for age, hypertension or smoking (p≥0.1). Patients with symptomatic carotid stenosis (N=46) had higher VWF:Ag and VWF:Ag II levels than controls at all time-points (p≤0.002). There was no significant correlation between platelet activation status and VWF:Ag or VWF:Ag II levels. VWF:Ag and VWF:Ag II levels are increased in an overall TIA and ischaemic stroke population, especially in patients with recently symptomatic carotid stenosis. VWF:Ag II was not superior to VWF:Ag at detecting acute endothelial activation in this cohort and might reflect timing of blood sampling in our study. Copyright © 2017 Elsevier B.V. All rights reserved.

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. © 2014 John Wiley & Sons Ltd.

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

Detailed von Willebrand factor multimer analysis in patients with von Willebrand disease in the European study, molecular and clinical markers for the diagnosis and management of type 1 von Willebrand disease (MCMDM-1VWD).

PubMed

Budde, U; Schneppenheim, R; Eikenboom, J; Goodeve, A; Will, K; Drewke, E; Castaman, G; Rodeghiero, F; Federici, A B; Batlle, J; Pérez, A; Meyer, D; Mazurier, C; Goudemand, J; Ingerslev, J; Habart, D; Vorlova, Z; Holmberg, L; Lethagen, S; Pasi, J; Hill, F; Peake, I

2008-05-01

Type 1 von Willebrand disease (VWD) is a congenital bleeding disorder characterized by a partial quantitative deficiency of plasma von Willebrand factor (VWF) in the absence of structural and/or functional VWF defects. Accurate assessment of the quantity and quality of plasma VWF is difficult but is a prerequisite for correct classification. To evaluate the proportion of misclassification of patients historically diagnosed with type 1 VWD using detailed analysis of the VWF multimer structure. Previously diagnosed type 1 VWD families and healthy controls were recruited by 12 expert centers in nine European countries. Phenotypic characterization comprised plasma VWF parameters and multimer analysis using low- and intermediate-resolution gels combined with an optimized visualization system. VWF genotyping was performed in all index cases (ICs). Abnormal multimers were present in 57 out of 150 ICs; however, only 29 out of these 57 (51%) had VWF ristocetin cofactor to antigen ratio below 0.7. In most cases multimer abnormalities were subtle, and only two cases had a significant loss of the largest multimers. Of the cases previously diagnosed as type 1 VWD, 38% showed abnormal multimers. Depending on the classification criteria used, 22 out of these 57 cases (15% of the total cohort) may be reclassified as type 2, emphasizing the requirement for multimer analysis compared with a mere ratio of VWF functional parameters and VWF:Ag. This is further supported by the finding that even slightly aberrant multimers are highly predictive for the presence of VWF mutations.

Clinical and laboratory diagnosis of von Willebrand disease: A synopsis of the 2008 NHLBI/NIH guidelines

PubMed Central

Nichols, William L.; Rick, Margaret E.; Ortel, Thomas L.; Montgomery, Robert R.; Sadler, J. Evan; Yawn, Barbara P.; James, Andra H.; Hultin, Mae B.; Manco-Johnson, Marilyn J.; Weinstein, Mark

2017-01-01

Von Willebrand factor (VWF) mediates blood platelet adhesion and accumulation at sites of blood vessel injury, and also carries coagulation factor VIII (FVIII) that is important for generating procoagulant activity. Von Willebrand disease (VWD), the most common inherited bleeding disorder, affects males and females, and reflects deficiency or defects of VWF that may also cause decreased FVIII. It may also occur less commonly as an acquired disorder (acquired von Willebrand syndrome). This article briefly summarizes selected features of the March 2008 evidence-based clinical and laboratory diagnostic recommendations from the National Heart, Lung, and Blood Institute (NHLBI) Expert Panel for assessment for VWD or other bleeding disorders or risks. Management of VWD is also addressed in the NHLBI guidelines, but is not summarized here. The VWD guidelines are available at the NHLBI Web site (http://www.nhlbi.nih.gov/guidelines/vwd). PMID:19415721

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

Targeting von Willebrand Factor in Ischaemic Stroke: Focus on Clinical Evidence.

PubMed

Buchtele, Nina; Schwameis, Michael; Gilbert, James C; Schörgenhofer, Christian; Jilma, Bernd

2018-06-01

Despite great efforts in stroke research, disability and recurrence rates in ischaemic stroke remain unacceptably high. To address this issue, one potential target for novel therapeutics is the glycoprotein von Willebrand factor (vWF), which increases in thrombogenicity especially under high shear rates as it bridges between vascular sub-endothelial collagen and platelets. The rationale for vWF as a potential target in stroke comes from four bodies of evidence. (1) Animal models which recapitulate the pathogenesis of stroke and validate the concept of targeting vWF for stroke prevention and the use of the vWF cleavage enzyme ADAMTS13 in acute stroke treatment. (2) Extensive epidemiologic data establishing the prognostic role of vWF in the clinical setting showing that high vWF levels are associated with an increased risk of first stroke, stroke recurrence or stroke-associated mortality. As such, vWF levels may be a suitable marker for further risk stratification to potentially fine-tune current risk prediction models which are mainly based on clinical and imaging data. (3) Genetic studies showing an association between vWF levels and stroke risk on genomic levels. Finally, (4) studies of patients with primary disorders of excess or deficiency of function in the vWF axis (e.g. thrombotic thrombocytopenic purpura and von Willebrand disease, respectively) which demonstrate the crucial role of vWF in atherothrombosis. Therapeutic inhibition of VWF by novel agents appears particularly promising for secondary prevention of stroke recurrence in specific sub-groups of patients such as those suffering from large artery atherosclerosis, as designated according to the TOAST classification. Schattauer GmbH Stuttgart.

Native multimer analysis of plasma and platelet von Willebrand factor compared to denaturing separation: implication for the interpretation of satellite bands.

PubMed

Hohenstein, Kurt; Griesmacher, Andrea; Weigel, Günter; Golderer, Georg; Ott, Helmut Werner

2011-06-01

Blue native electrophoresis (BNE) was applied to analyze the von Willebrand factor (vWF) multimers in their native state and to present a methodology to perform blue native electrophoresis on human plasma proteins, which has not been done before. The major difference between this method and the commonly used SDS-agarose gel electrophoresis is the lack of satellite bands in the high-resolution native gel. To further analyze this phenomenon, a second dimension was performed under denaturing conditions. Thereby, we obtained a pattern in which each protein sub-unit from the first dimension dissociates into three distinct sub-bands. These bands confirm the triplet structure, which consists of an intermediate band and two satellite bands. By introducing the second dimension, our novel method separates the triplet structure into a higher resolution than the commonly used SDS-agarose gel electrophoresis does. This helps considerably in the classification of ambiguous von Willebrand's disease subtypes. In addition, our method has the additional advantage of being able to resolve the triplet structure of platelet vWF multimers, which has not been identified previously through conventional SDS-agarose electrophoresis multimer analysis. This potential enables us to compare the triplet structure from platelet and plasmatic vWF, and may help to find out whether structural abnormalities concern the vWF molecule in the platelet itself, or whether they are due to the physiological processing of vWF shed into circulation. Owing to its resolution and sensitivity, this native separation technique offers a promising tool for the analysis and detection of von Willebrand disorder, and for the classification of von Willebrand's disease subtypes. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

DOE PAGES

Tischer, Alexander; Campbell, James C.; Machha, Venkata R.; ...

2015-12-16

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 limitedmore » 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 better stability stems from the steric consequences of adding a side chain (G1324A) and additionally a hydrogen bond (G1324S) to His 1322 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.« less

Clinical use of a rapid collagen binding assay for von Willebrand factor cleaving protease in patients with thrombotic thrombocytopenic purpura.

PubMed

Rick, Margaret E; Moll, Stephan; Taylor, Mark A; Krizek, Dennis M; White, Gilbert C; Aronson, David L

2002-10-01

A simple collagen binding assay (CBA) for measuring activity of the von Willebrand factor cleaving protease in clinical samples is described, and results of fifty masked plasmapheresis samples rom patients with TTP/HUS and other diseases are presented. There was 97.5% concordance between the CBA and a multimer gel assay. The CBA identified low protease activity in 78% of patients who had a clinical syndrome consistent with TTP/HUS and in 2 of 10 sick controls, giving it a positive predictive value of 0.94. The heterogeneity regarding the presence or absence of vWF protease activity in patients with TTP/HUS was confirmed by finding a low negative predictive value of 0.50 with the CBA. The CBA detected inhibitors of the protease in 26 of 29 patients (90%) with TTP/HUS and low protease activity levels. The CBA is a useful clinical assay for examining von Willebrand factor protease activity and detecting inhibitors against the protease.

Platelet Dysfunction and a High Bone Mass Phenotype in a Murine Model of Platelet-Type von Willebrand Disease

PubMed Central

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

2008-01-01

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. PMID:18187573

Conventional Rapid Latex Agglutination in Estimation of von Willebrand Factor: Method Revisited and Potential Clinical Applications

PubMed Central

Che Hussin, Che Maraina

2014-01-01

Measurement of von Willebrand factor antigen (VWF : Ag) levels is usually performed in a specialised laboratory which limits its application in routine clinical practice. So far, no commercial rapid test kit is available for VWF : Ag estimation. This paper discusses the technical aspect of latex agglutination method which was established to suit the purpose of estimating von Willebrand factor (VWF) levels in the plasma sample. The latex agglutination test can be performed qualitatively and semiquantitatively. Reproducibility, stability, linearity, limit of detection, interference, and method comparison studies were conducted to evaluate the performance of this test. Semiquantitative latex agglutination test was strongly correlated with the reference immunoturbidimetric assay (Spearman's rho = 0.946, P < 0.001, n = 132). A substantial agreement (κ = 0.77) was found between qualitative latex agglutination test and the reference assay. Using the scoring system for the rapid latex test, no agglutination is with 0% VWF : Ag (control negative), 1+ reaction is equivalent to <20% VWF : Ag, and 4+ reaction indicates >150% VWF : Ag (when comparing with immunoturbidimetric assay). The findings from evaluation studies suggest that latex agglutination method is suitable to be used as a rapid test kit for the estimation of VWF : Ag levels in various clinical conditions associated with high levels and low levels of VWF : Ag. PMID:25759835

Dominant von Willebrand disease type 2A groups I and II due to missense mutations in the A2 domain of the von Willebrand factor gene: diagnosis and management.

PubMed

Michiels, Jan Jacques; van Vliet, Huub H D M

2009-01-01

Pertinent findings in patients with von Willebrand disease (VWD) type 2A include prolonged bleeding time (BT), consistently low von Willebrand factor (VWF):ristocetin cofactor activity (RCo)/antigen concentration (Ag) and VWF:collagen binding (CB)/Ag ratios, absence of high, and (depending on severity) intermediate and large VWF multimers, the presence of pronounced triplet structure of individual bands and increased VWF degradation products due to increased proteolysis caused by mutations in the A2 domain of VWF. Two categories of VWD type 2A can be distinguished: group I with severe and group II with mild VWD. A minority of VWD type 2A have mild VWD characterized by near normal to prolonged BT, normal factor VIII coagulant activity and VWF:Ag, low VWF:RCo and VWF:CB, a normal ristocetin-induced platelet aggregation and complete but transient correction of BT and functional VWF parameters to normal levels for only a few hours due to short half-lives for VWF:RCo and CWF:CB. Such transient complete responses to desmopressin (DDAVP) lasting only a few hours may facilitate treatment and prophylaxis of minor bleedings, but may not be able to prevent bleeding during minor and major surgery. Most VWD type 2A patients have pronounced VWD with very low VWF:RCo, prolonged BT, PFA-100 closure times >250 s, and response to DDAVP is only transient, minor, poor or absent, with no correction of the BT despite some increase in VWF:RCo, thus being candidates for factor VIII-VWF concentrate substitution for the acute and prophylactic treatment of bleeding symptoms. Copyright (c) 2009 S. Karger AG, Basel.

Key role of glycoprotein Ib/V/IX and von Willebrand factor in platelet activation-dependent fibrin formation at low shear flow

PubMed Central

Cosemans, Judith M. E. M.; Schols, Saskia E. M.; Stefanini, Lucia; de Witt, Susanne; Feijge, Marion A. H.; Hamulyák, Karly; Deckmyn, Hans; Bergmeier, Wolfgang

2011-01-01

A microscopic method was developed to study the role of platelets in fibrin formation. Perfusion of adhered platelets with plasma under coagulating conditions at a low shear rate (250−1) resulted in the assembly of a star-like fibrin network at the platelet surface. The focal fibrin formation on platelets was preceded by rises in cytosolic Ca2+, morphologic changes, and phosphatidylserine exposure. Fibrin formation was slightly affected by αIIbβ3 blockage, but it was greatly delayed and reduced by the following: inhibition of thrombin or platelet activation; interference in the binding of von Willebrand factor (VWF) to glycoprotein Ib/V/IX (GpIb-V-IX); plasma or blood from patients with type 1 von Willebrand disease; and plasma from mice deficient in VWF or the extracellular domain of GpIbα. In this process, the GpIb-binding A1 domain of VWF was similarly effective as full-length VWF. Prestimulation of platelets enhanced the formation of fibrin, which was abrogated by blockage of phosphatidylserine. Together, these results show that, in the presence of thrombin and low shear flow, VWF-induced activation of GpIb-V-IX triggers platelet procoagulant activity and anchorage of a star-like fibrin network. This process can be relevant in hemostasis and the manifestation of von Willebrand disease. PMID:21037087

Role of carbohydrate in multimeric structure of factor VIII/von Willebrand factor protein.

PubMed Central

Gralnick, H R; Williams, S B; Rick, M E

1983-01-01

The carbohydrate moiety of the factor VIII/von Willebrand (vW) factor protein is important in the expression of vW factor activity and the intravascular survival of the protein. Studies of normal human factor VIII/vW factor protein indicate that there is a requirement of a full complement of penultimate galactose for the maintenance of a normal multimeric structure. Release of penultimate galactose by beta-galactosidase or modification by galactose oxidase results in loss of the largest molecular weight multimers and increased numbers of intermediate and smaller multimers. In contrast, terminal galactose on the factor VIII/vW factor protein does not appear to play a significant role in the maintenance of the multimer organization. The abnormalities in multimeric structure and molecular size were demonstrated by NaDodSO4/polyacrylamide/agarose gel electrophoresis, NaDodSO4/glyoxyl-agarose electrophoresis, and sucrose density ultracentrifugation. These studies indicate that the penultimate galactose plays a role in the maintenance of the largest multimers of the factor VIII/vW factor protein. This may explain why, in some patients with variant forms of vW disease, a carbohydrate abnormality also may affect the multimeric structure of the plasma factor VIII/vW factor protein. Images PMID:6601805

Mutant botrocetin-2 inhibits von Willebrand factor-induced platelet agglutination.

PubMed

Matsui, T; Hori, A; Hamako, J; Matsushita, F; Ozeki, Y; Sakurai, Y; Hayakawa, M; Matsumoto, M; Fujimura, Y

2017-03-01

Essentials Botrocetin-2 (Bot2) binds to von Willebrand factor (VWF) and induces platelet agglutination. We identified Bot2 residues that are required for binding to VWF and glycoprotein (GP) Ib. We produced a mutant Bot2 that binds to VWF but inhibits platelet agglutination. Mutant Bot2 could be used as a potential anti-thrombotic reagent to block VWF-GPIb interaction. Background Botrocetin-2 (Bot2) is a botrocetin-like protein composed of α and β subunits that have been cloned from the snake Bothrops jararaca. Bot2 binds specifically to von Willebrand factor (VWF), and the complex induces glycoprotein (GP) Ib-dependent platelet agglutination. Objectives To exploit Bot2's VWF-binding capacity in order to attempt to create a mutant Bot2 that binds to VWF but inhibits platelet agglutination. Methods and Results Several point mutations were introduced into Bot2 cDNA, and the recombinant protein (recombinant Bot2 [rBot2]) was purified on an anti-botrocetin column. The mutant rBot2 with either Ala at Asp70 in the β subunit (Aspβ70Ala), or Argβ115Ala and Lysβ117Ala, showed reduced platelet agglutination-inducing activity. rBot2 with Aspβ70Ala showed little binding activity towards immobilized VWF on an ELISA plate, whereas rBot2 with Argβ115Ala/Lysβ117Ala showed reduced binding activity towards GPIb (glycocalicin) after forming a complex with VWF. rBot2 point-mutated to oppositely charged Glu at both Argβ115 and Lysβ117 showed normal binding activity towards VWF but no platelet-agglutinating activity. Furthermore, this doubly mutated protein inhibited ristocetin-induced or high shear stress-induced platelet aggregation, and restrained thrombus formation under flow conditions. Conclusions Asp70 in the β subunit of botrocetin is important for VWF binding, and Arg115 and Lys117 in the β subunit are essential for interaction with GPIb. Doubly mutated rBot2, with Argβ115Glu and Lysβ117Glu, repels GPIb and might have potential as an antithrombotic reagent that

Diagnosis and management of von Willebrand disease: a developing country perspective.

PubMed

Nair, Sukesh Chandran; Viswabandya, Auro; Srivastava, Alok

2011-07-01

Special challenges exist in the management of patients with von Willebrand disease (VWD) because of limitations in diagnostic facilities and therapeutic options. However, even within these limitations, it is possible to establish comprehensive services for this condition. Our data show that among 202 patients with VWD, 107 were type 3, 62 were type 1, and the others different categories of type 2. Basic tests such as bleeding time and activated partial thromboplastin time with factor (F)VIII coagulant are able to diagnose most of those with severe disease. We have been able to adapt the specific tests such as von Willebrand factor (VWF) ristocetin cofactor and VWF antigen from the tedious batched manual methods to cost-effective automated methods on advanced coagulometers. Discriminatory tests such as VWF collagen binding, VWF:FVIIIB, ristocetin-induced platelet agglutination (RIPA) are done in batches. Therapeutic options and for the treatment of bleeding include desmopressin, cryoprecipitate, and intermediate purity VWF-containing clotting factor concentrates. Tranexamic acid is also widely used as well as hormonal therapy for menorrhagia. We have also shown that modest doses of intermediate purity FVIII (Koate DVI; Talecris Biotherapeutics, Raleigh, NC, USA) at 35 IU/kg preoperatively and 10 to 20 IU/kg after that are sufficient for surgical hemostasis in these patients. © Thieme Medical Publishers.

Comparative analysis of von Willebrand factor profiles after implantation of left ventricular assist device and total artificial heart.

PubMed

Reich, H J; Morgan, J; Arabia, F; Czer, L; Moriguchi, J; Ramzy, D; Esmailian, F; Lam, L; Dunhill, J; Volod, O

2017-08-01

Essentials Bleeding is a major source of morbidity during mechanical circulatory support. von Willebrand factor (VWF) multimer loss may contribute to bleeding. Different patterns of VWF multimer loss were seen with the two device types. This is the first report of total artificial heart associated VWF multimer loss. Background Bleeding remains a challenge during mechanical circulatory support and underlying mechanisms are incompletely understood. Functional von Willebrand factor (VWF) impairment because of loss of high-molecular-weight multimers (MWMs) produces acquired von Willebrand disease (VWD) after left ventricular assist device (LVAD). Little is known about VWF multimers with total artificial hearts (TAHs). Here, VWF profiles with LVADs and TAHs are compared using a VWD panel. Methods VWD evaluations for patients with LVAD or TAH (2013-14) were retrospectively analyzed and included: VWF activity (ristocetin cofactor, VWF:RCo), VWF antigen (VWF:Ag), ratio of VWF:RCo to VWF:Ag, and quantitative VWF multimeric analysis. Results Twelve patients with LVADs and 12 with TAHs underwent VWD evaluation. All had either normal (47.8%) or elevated (52.2%) VWF:RCo, normal (26.1%) or elevated (73.9%) VWF:Ag and 50.0% were disproportional (ratio ≤ 0.7). Multimeric analysis showed abnormal patterns in all patients with LVADs: seven with high MWM loss; five with highest MWM loss. With TAH, 10/12 patients had abnormal patterns: all with highest MWM loss. High MWM loss correlated with presence of LVAD and highest MWM loss with TAH. Increased low MWMs were detected in 22/24. Conclusion Using VWF multimeric analysis, abnormalities after LVAD or TAH were detected that would be missed with measurements of VWF level alone: loss of high MWM predominantly in LVAD, loss of highest MWM in TAH, and elevated levels of low MWM in both. This is the first study to describe TAH-associated highest MWM loss, which may contribute to bleeding. © 2017 International Society on Thrombosis and

Transfusion medicine management for reconstructive spinal repair in a patient with von Willebrand's disease and a history of heavy surgical bleeding.

PubMed

Bolan, C D; Rick, M E; Polly, D W

2001-12-01

A case report of a multidisciplinary approach to a second reconstructive back surgery in a patient with von Willebrand's disease, flatback syndrome, and a history of heavy surgical bleeding is presented. To review the perioperative planning and assessment of hemostasis and transfusion medicine management, including administration of Humate P, a Factor VIII preparation with high von Willebrand factor content. Reconstructive spinal procedures may require significant transfusion support even in patients with normal preoperative hemostasis. In addition to the hemostatic problem caused by von Willebrand's disease, the reported patient requested minimal exposure to allogeneic blood products because of hepatitis C infection acquired from previous transfusions. The multidisciplinary team included the patient, hematologist, blood bank medical director, anesthesiologist, and operating surgeon. Preoperative assessment showed a Type 2A von Willebrand's disease variant. A careful planning process included a test infusion of desmopressin and extensive autologous donations of red cells, plasma, and platelets, which were collected before the procedure. Anterior and posterior spine fusions were performed during a 14-hour procedure. Hemostasis and clinical response were excellent. Humate P was administered perioperatively as assessed by the baseline Factor VIII and von Willebrand's disease levels, the plasma volume, the half-life of infused Humate P, and the anticipated risk and tolerance for bleeding. The estimated blood loss was 5 L. Replacement included 9 units of autologous red cells, 6 units of autologous plasma, 2 autologous plateletpheresis collections, a single allogeneic plateletpheresis product, and 17,000 units of Humate P administered over the perioperative period. Using a careful multidisciplinary approach, excellent hemostasis can be achieved with minimal exposure to untreated allogeneic blood products during aggressive spinal surgery in a patient with a clinically

Desmopressin therapy to assist the functional identification and characterisation of von Willebrand disease: differential utility from combining two (VWF:CB and VWF:RCo) von Willebrand factor activity assays?

PubMed

Favaloro, Emmanuel J; Thom, Jim; Patterson, David; Just, Sarah; Dixon, Tracy; Koutts, Jerry; Baccala, Maria; Rowell, John; Baker, Ross

2009-04-01

We performed a retrospective audit of desmopressin (DDAVP) usage to assist in the functional characterisation of von Willebrand disease (VWD). Data was evaluated for 208 patients, comprising those with VWD (Type 1 [n=160], Type 2A [n=19], Type 2M [n=10]), plus 19 individuals with haemophilia or carriers of haemophilia. Laboratory testing comprised pre- and post-DDAVP evaluation of factor VIII (FVIII:C), von Willebrand factor (VWF) antigen (VWF:Ag), VWF ristocetin cofactor (VWF:RCo) activity, VWF collagen binding (VWF:CB) activity, and in one laboratory an alternate VWF activity assay. In brief, combined usage of VWF:RCo and VWF:CB appears to provide improved functional characterisation and/or 'classification' of VWD types, in particular better differentiation of Type 2A and 2M VWD, and clearer validation of a Type 1 VWD diagnosis. Thus, (i) Type 1 VWD displayed generally good absolute and relative rises in all test parameters, although relative rises were greatest for FVIII:C and VWF:CB, and CB/Ag ratio increases overshadowed those for RCo/Ag; (ii) Type 2A VWD patients showed good absolute and relative rises in both FVIII:C and VWF:Ag, but poor absolute rises in both VWF:CB and VWF:RCo; although small rises in both CB/Ag and RCo/Ag were also observed, both ratios tended to remain below 0.7; (iii) finally, Type 2 M VWD patients generally showed good absolute and relative rises in FVIII:C, VWF:Ag and VWF:CB, but a poor absolute and relative rise in VWF:RCo; thus, there were good rises in CB/Ag ratios but little change in RCo/Ag, which tended to remain below 0.7. Future multi-centre prospective investigations are warranted to validate these findings and to investigate their therapeutic implications.

Cerebral venous thrombosis associated with thyrotoxicosis, the use of desmopressin and elevated factor VIII/von Willebrand factor.

PubMed

Waheed, Waqar; Aljerdi, Salman; Decker, Barbara; Cushman, Mary; Hamill, Robert W

2016-08-08

Cerebral venous thrombosis (CVT) is an uncommon disorder associated with diverse processes. We report a patient who, while receiving desmopressin and contraceptive pills (OCP), developed straight sinus thrombosis. Clinical assessment and laboratory investigations revealed untreated hyperthyroidism and a hypercoagulable state, characterised by high levels of von Willebrand factor, factor VIII coagulant activity and IgM cardiolipin antibody. The clinical picture improved with anticoagulation, treatment of hyperthyroidism and discontinuation of OCP and desmopressin. To the best of our knowledge, the association between the use of oral desmopressin and CVT has not been described. The multiple risk factors present in our case were probably additive in increasing the risk of CVT. Although this case represents a rare occurrence, practitioners should be alerted to the possible associations of desmopressin, oral contraceptives and Graves' disease with venous thrombosis. 2016 BMJ Publishing Group Ltd.

Investigating the Mechanical Properties of Plasma von Willebrand Factor Using Atomic Force Microscopy

NASA Astrophysics Data System (ADS)

Wijeratne, Sitara; Botello, Eric; Yeh, Hui-Chun; Zhou, Zhou; Bergeron, Angela; Frey, Eric; Moake, Joel; Dong, Jing-Fei; Kiang, Ching-Hwa

2011-10-01

Single-molecule manipulation allows us to study the real-time kinetics of complex cellular processes. The mechanochemistry of different forms of von Willebrand factor (VWF) and their receptor-ligand binding kinetics can be probed by atomic force microscopy (AFM). Since plasma VWF can be activated upon shear, the structural and functional properties of VWF that are critical in mediating thrombus formation become important. Here we characterized the mechanical resistance to domain unfolding of VWF to determine its conformational states. We found the shear-induced conformational changes, hence the mechanical property, can be detected by the change in unfolding forces. The relaxation rate of such effect is much longer than expected. Our results offer an insight in establishing strategies for regulating VWF adhesion activity, increasing our understanding of surface-induced thrombosis as mediated by VWF.

Modeling Shear Induced Von Willebrand Factor Binding to Collagen

NASA Astrophysics Data System (ADS)

Dong, Chuqiao; Wei, Wei; Morabito, Michael; Webb, Edmund; Oztekin, Alparslan; Zhang, Xiaohui; Cheng, Xuanhong

2017-11-01

Von Willebrand factor (vWF) is a blood glycoprotein that binds with platelets and collagen on injured vessel surfaces to form clots. VWF bioactivity is shear flow induced: at low shear, binding between VWF and other biological entities is suppressed; for high shear rate conditions - as are found near arterial injury sites - VWF elongates, activating its binding with platelets and collagen. Based on parameters derived from single molecule force spectroscopy experiments, we developed a coarse-grain molecular model to simulate bond formation probability as a function of shear rate. By introducing a binding criterion that depends on the conformation of a sub-monomer molecular feature of our model, the model predicts shear-induced binding, even for conditions where binding is highly energetically favorable. We further investigate the influence of various model parameters on the ability to predict shear-induced binding (vWF length, collagen site density and distribution, binding energy landscape, and slip/catch bond length) and demonstrate parameter ranges where the model provides good agreement with existing experimental data. Our results may be important for understanding vWF activity and also for achieving targeted drug therapy via biomimetic synthetic molecules. National Science Foundation (NSF),Division of Mathematical Sciences (DMS).

Performance evaluation and multicentre study of a von Willebrand factor activity assay based on GPIb binding in the absence of ristocetin.

PubMed

Patzke, Juergen; Budde, Ulrich; Huber, Andreas; Méndez, Adriana; Muth, Heidrun; Obser, Tobias; Peerschke, Ellinor; Wilkens, Matthias; Schneppenheim, Reinhard

2014-12-01

The functional activity of von Willebrand factor (VWF) is most frequently measured by using the ristocetin cofactor assay (VWF:RCo). However, the method's drawbacks include unsatisfactory precision, sensitivity and availability of automated system applications. We have developed an alternative assay (INNOVANCE VWF Ac) that is based on the binding of VWF to recombinant glycoprotein Ib (GPIb). Two gain-of-function mutations were introduced into a GPIb fragment, allowing an assay format without ristocetin. Fully automated assay applications are available for the BCS/BCS XP systems and the Sysmex CS-2000i, Sysmex CA-7000, Sysmex CA-1500 and Sysmex CA-560 systems.The INNOVANCE VWF Ac assay measuring range extends from 4 to 600% VWF for all systems except the Sysmex CA-560 system. Within-device precision values were found to be between 2 and 7%. The limit of detection was below 2.2% VWF. In a study on the BCS XP system, a total number of 580 sample results yielded a correlation to the VWF:RCo assay of r equal to 0.99 (slope = 0.96). Very similar results were observed when von Willebrand disease samples type 1, 2A, 2B, 2M, 2N and 3 were investigated with the new assay and the VWF:RCo assay. The excellent performance data and comparability to VWF:RCo, together with the ease of use, led us to the conclusion that the ristocetin cofactor assay can be replaced by the new GPIb-binding assay to reliably diagnosing patients with von Willebrand disease.

Hemophilia and von Willebrand's disease: 1. Diagnosis, comprehensive care and assessment. Association of Hemophilia Clinic Directors of Canada.

PubMed Central

1995-01-01

OBJECTIVE: To present current strategies for the assessment and comprehensive care of patients with hemophilia and von Willebrand's disease. OPTIONS: Hospital care, home care, single-provider care and multidisciplinary care. 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 own 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 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: The optimal use of treatment procedures and home care offers patients the advantages of minimized disability, improved survival and financial benefit. It is also cost effective. Potential harm, including the risk of hepatitis B, hepatitis C and HIV infection, has now been minimized through viral inactivation of plasma-derived coagulation-factor concentrates and through the use of recombinant clotting factor concentrates and other non-plasma-derived hemostatic agents. RECOMMENDATIONS: Patients with hemophilia and severe von Willebrand's disease should be followed in comprehensive care centres that offer expertise in the diagnosis, assessment and management of bleeding and complications and that can meet the educational and

Emergency department care for patients with hemophilia and von Willebrand disease.

PubMed

Singleton, Tammuella; Kruse-Jarres, Rebecca; Leissinger, Cindy

2010-08-01

Patients with bleeding disorders such as hemophilia A, hemophilia B, and von Willebrand disease (VWD) are routinely treated at home, with their care managed in specialized centers. In emergency situations, these patients often present to their local emergency department (ED), where their management can represent a challenge to the emergency physicians and staff who rarely encounter them. Delays in diagnosis and administration of replacement therapy are the factors most commonly identified as predictive of death. Patients and family members are often very well educated in the disease and its management, which can significantly reduce morbidity and mortality. Children with bleeding disorders confer different challenges to the emergency physician and staff: they may present with no obvious signs of trauma or they may present with bruises consistent with non-accidental injury. All possible causes of bruising/bleeding should be investigated, although treatment should be administered promptly. The initial presentation of a bleeding disorder in the pediatric population is often made in the ED. Treatment of hemophilia A and B requires rapid replacement of the deficient clotting factor, with the desired factor level and dosage dependent on the product used and the hemorrhagic situation encountered. In patients with VWD, the main treatments are desmopressin or intravenous infusion of plasma-derived concentrates containing factor VIII and von Willebrand factor. The aim of this review is to outline some of the issues facing emergency physicians and the options available for the treatment of patients with hemophilia A, hemophilia B, and VWD. Copyright 2010. Published by Elsevier Inc.

Plasma and urinary endothelin-1 titers and plasma von Willebrand activity in Pseudoxanthoma elasticum.

PubMed

Amadeo, A; Bertulezzi, G; Civelli, L; Porta, C; Moroni, M

1998-10-01

We found high endothelin-1 and von Willebrand factor plasma titers not only in two individuals (daughter and father) affected with Pseudoxanthoma elasticum but also in a young unaffected relative. These findings raise the possibility that these molecules could be the first biochemical fingerprints of this, still not clinically evident, rare inherited disorder of elastic tissue.

Detection of von Willebrand factor and tissue factor in platelets-fibrin rich coronary thrombi in acute myocardial infarction.

PubMed

Yamashita, Atsushi; Sumi, Takahiro; Goto, Shinya; Hoshiba, Yasunari; Nishihira, Kensaku; Kawamoto, Riichirou; Hatakeyama, Kinta; Date, Haruhiko; Imamura, Takuroh; Ogawa, Hisao; Asada, Yujiro

2006-01-01

The rapid closure of coronary arteries due to occlusive thrombi is the major cause of acute myocardial infarction. However, the mechanisms of coronary thrombus formation have not been elucidated. We immunohistochemically assessed the localizations and their changes over time of glycoprotein IIb/IIIa, fibrin, von Willebrand factor (vWF), and tissue factor (TF), after the onset of chest pain (<4, 4 to 6, or 6 to 12 hours), in fresh coronary thrombi causing acute myocardial infarction. The occlusive thrombi were consistently composed of platelets, fibrin, vWF, and TF from the early phase of onset, and glycoprotein IIb/IIIa and fibrin were closely associated with vWF and TF, respectively. vWF and/or TF may contribute to occlusive thrombus formation and be novel therapeutic candidates for treating patients with coronary thrombosis.

Von Willebrand factor, a versatile player in gastrointestinal bleeding in left ventricular assist device recipients?

PubMed

Fischer, Quentin; Huisse, Marie-Geneviève; Voiriot, Guillaume; Caron, Claudine; Lepage, Laurent; Dilly, Marie-Pierre; Nataf, Patrick; Ajzenberg, Nadine; Kirsch, Matthias

2015-01-01

Bleeding originating in the gastrointestinal (GI) tract is one of the most common adverse events after left ventricular assist device (LVAD) implantation. In these patients, GI bleeding appears to be the consequence of altered hemostasis on the one hand and alterations of the GI microvasculature on the other. We report the case of a patient who suffered repeated, severe GI bleeding early after implantation of a HeartMate II continuous-flow LVAD. After failure of conventional treatment strategies, GI bleeding was controlled using repeated transfusions of a purified von Willebrand factor (VWF) concentrate, almost devoid of Factor VIII (Wilfactin, LFB). No episodes of pump thrombosis were noted. Subsequent to VWF transfusions, we observed a progressive normalization of circulating vascular endothelial growth factor levels. Our data raise the possibility that, in addition to its hemostatic properties, transfusions of VWF might have acted as an antiangiogenic factor. © 2014 AABB.

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.

Genome-wide association studies identify genetic loci for low von Willebrand factor levels

PubMed Central

van Loon, Janine; Dehghan, Abbas; Weihong, Tang; Trompet, Stella; McArdle, Wendy L; Asselbergs, Folkert F W; Chen, Ming-Huei; Lopez, Lorna M; Huffman, Jennifer E; Leebeek, Frank W G; Basu, Saonli; Stott, David J; Rumley, Ann; Gansevoort, Ron T; Davies, Gail; Wilson, James J F; Witteman, Jacqueline C M; Cao, Xiting; de Craen, Anton J M; Bakker, Stephan J L; Psaty, Bruce M; Starr, John M; Hofman, Albert; Wouter Jukema, J; Deary, Ian J; Hayward, Caroline; van der Harst, Pim; Lowe, Gordon D O; Folsom, Aaron R; Strachan, David P; Smith, Nicolas; de Maat, Moniek P M; O'Donnell, Christopher

2016-01-01

Low von Willebrand factor (VWF) levels are associated with bleeding symptoms and are a diagnostic criterion for von Willebrand disease, the most common inherited bleeding disorder. To date, it is unclear which genetic loci are associated with reduced VWF levels. Therefore, we conducted a meta-analysis of genome-wide association studies to identify genetic loci associated with low VWF levels. For this meta-analysis, we included 31 149 participants of European ancestry from 11 community-based studies. From all participants, VWF antigen (VWF:Ag) measurements and genome-wide single-nucleotide polymorphism (SNP) scans were available. Each study conducted analyses using logistic regression of SNPs on dichotomized VWF:Ag measures (lowest 5% for blood group O and non-O) with an additive genetic model adjusted for age and sex. An inverse-variance weighted meta-analysis was performed for VWF:Ag levels. A total of 97 SNPs exceeded the genome-wide significance threshold of 5 × 10−8 and comprised five loci on four different chromosomes: 6q24 (smallest P-value 5.8 × 10−10), 9q34 (2.4 × 10−64), 12p13 (5.3 × 10−22), 12q23 (1.2 × 10−8) and 13q13 (2.6 × 10−8). All loci were within or close to genes, including STXBP5 (Syntaxin Binding Protein 5) (6q24), STAB5 (stabilin-5) (12q23), ABO (9q34), VWF (12p13) and UFM1 (ubiquitin-fold modifier 1) (13q13). Of these, UFM1 has not been previously associated with VWF:Ag levels. Four genes that were previously associated with VWF levels (VWF, ABO, STXBP5 and STAB2) were also associated with low VWF levels, and, in addition, we identified a new gene, UFM1, that is associated with low VWF levels. These findings point to novel mechanisms for the occurrence of low VWF levels. PMID:26486471

Probing the Mechanical Properties of Plasma von Willebrand Factor Using Atomic Force Microscopy

NASA Astrophysics Data System (ADS)

Wijeratne, Sitara; Botello, Eric; Frey, Eric; Kiang, Ching-Hwa; Dong, Jing-Fei; Yeh, Hui-Chun

2010-03-01

Single-molecule manipulation allows us to study the real time kinetics of many complex cellular processes. The mechanochemistry of different forms of von Willebrand factor (VWF) and their receptor-ligand binding kinetics can be unraveled by atomic force microscopy (AFM). Since plasma VWF can be activated upon shear, the structural and functional properties of VWF are critical in mediating thrombus formation become important. Here we characterized the mechanical resistance to domain unfolding of VWF to determine the conformational states of VWF. We found the shear induced conformational, hence mechanical property changes can be detected by the change in unfolding forces. The relaxation rate of such effect is much longed than expected. This supports the model of lateral association VWF under shear stress. Our results offer an insight in establishing strategies for regulating VWF adhesion activity, increasing our understanding of surface-induced thrombosis as mediated by VWF.

Remission of recurrent gastrointestinal bleeding after septal reduction therapy in patients with hypertrophic obstructive cardiomyopathy-associated acquired von Willebrand syndrome.

PubMed

Blackshear, J L; Stark, M E; Agnew, R C; Moussa, I D; Safford, R E; Shapiro, B P; Waldo, O A; Chen, D

2015-02-01

Gastrointestinal hemorrhage is considered to be a severe complication of von Willebrand disease. The optimal therapy for acquired von Willebrand syndrome and severe gastrointestinal bleeding with hypertrophic cardiomyopathy is undefined. Seventy-seven patients (median age, 67 years; interquartile range [IQR], 56-75 years; 49% women) with hypertrophic cardiomyopathy underwent von Willebrand factor multimer testing and acquisition of bleeding history. Bleeding was detected in 27 (36%) (median age, 74 years; IQR 66-76 years; 74% women), 20 with gastrointestinal bleeding, including 11 women with transfusion dependence. In these 11 women, the median duration of transfusion dependency was 36 months (IQR 18-44 months), and the median number of transfusions required was 25 (IQR 20-38). Two patients had undergone bowel resection for bleeding, one of them twice. Seven patients showed angiodysplasia, and the remainder had no endoscopic lesion. Bleeding recurred after bowel surgery or endoscopic intervention and medical therapy for hypertrophic cardiomyopathy in 10 of 11 patients. Two patients had septal myectomy, and six patients underwent alcohol septal ablation. With the exception of one patient in whom a significant gradient persisted after septal ablation, after the periprocedural period, patients after septal reduction therapy remained free of recurrent bleeding and need for transfusions. Acquired von Willebrand syndrome is common in hypertrophic cardiomyopathy. Gastrointestinal bleeding often recurs after endoscopic therapy, but may be relieved by structural cardiac repair. © 2014 International Society on Thrombosis and Haemostasis.

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

PubMed

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; Ewenstein, Bruce M

2013-08-01

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.

Recurrent haematomas of the thigh: a case of von Willebrand's disease presenting to a sports clinic

PubMed Central

Owens, S.; Baglin, T.

2000-01-01

Von Willebrand's disease is a relatively common mild form of haemophilia. It should be suspected in assessing sports injuries when excessive bleeding occurs in response to relatively mild trauma. Those with the disease should remain active but avoid contact sports. They should not take aspirin or non-steroidal anti-inflammatory drugs, which may exacerbate bleeding, and should be given supportive treatment to cover dental extraction, surgery, or significant bleeding episodes. Key Words: von Willebrand's disease; haemophilia; haematoma; sports clinic PMID:10786868

Potential misdiagnosis of von Willebrand disease and haemophilia caused by ineffective mixing of thawed plasma.

PubMed

Favaloro, E J; Oliver, S; Mohammed, S; Ahuja, M; Grzechnik, E; Azimulla, S; McDonald, J; Lima-Oliveira, G; Lippi, G

2017-09-01

von Willebrand disease (VWD) reflects a loss or dysfunction in von Willebrand factor (VWF), while haemophilia represents a loss or dysfunction of clotting factors such as factor VIII (FVIII) or FIX. Their diagnosis requires laboratory testing, with this potentially compromised by preanalytical events, including poor sample quality. This study assessed the effect of inadequate mixing as a potential cause of VWD and haemophilia misdiagnosis. After completion of requested testing, 48 consecutive patient samples comprising separate aliquots from single collections were individually pooled, appropriately mixed, then frozen in separate aliquots, either at -20°C or -80°C for 2-7 days. Each sample set was then thawed and the separate aliquots subjected to separate mixing protocols (several inversions, blood roller, vortex) vs a non-mix sample, and all aliquots then tested for various VWF and factor assays. Non-mixing led to substantial reduction in VWF and factors in about 25% of samples, that in some cases could lead to misdiagnosis of VWD or haemophilia. Interestingly, there were also some differences observed with respect to different mixing protocols. Our study identified ineffective or variable mixing of thawed plasma samples as potential causes of misdiagnosis of VWD or haemophilia. Further education regarding the importance of appropriate mixing appears warranted. © 2017 John Wiley & Sons Ltd.

Identification and characterization of the elusive mutation causing the historical von Willebrand Disease type IIC Miami.

PubMed

Obser, T; Ledford-Kraemer, M; Oyen, F; Brehm, M A; Denis, C V; Marschalek, R; Montgomery, R R; Sadler, J E; Schneppenheim, S; Budde, U; Schneppenheim, R

2016-09-01

Essentials Von Willebrand disease IIC Miami features high von Willebrand factor (VWF) with reduced function. We aimed to identify and characterize the elusive underlying mutation in the original family. An inframe duplication of VWF exons 9-10 was identified and characterized. The mutation causes a defect in VWF multimerization and decreased VWF clearance from the circulation. Background A variant of von Willebrand disease (VWD) type 2A, phenotype IIC (VWD2AIIC), is characterized by recessive inheritance, low von Willebrand factor antigen (VWF:Ag), lack of VWF high-molecular-weight multimers, absence of VWF proteolytic fragments and mutations in the VWF propeptide. A family with dominantly inherited VWD2AIIC but markedly elevated VWF:Ag of > 2 U L(-1) was described as VWD type IIC Miami (VWD2AIIC-Miami) in 1993; however, the molecular defect remained elusive. Objectives To identify the molecular mechanism underlying the phenotype of the original VWD2AIIC-Miami. Patients and Methods We studied the original family with VWD2AIIC-Miami phenotypically and by genotyping. The identified mutation was recombinantly expressed and characterized by standard techniques, confocal imaging and in a mouse model, respectively. Results By Multiplex ligation-dependent probe amplification we identified an in-frame duplication of VWF exons 9-10 (c.998_1156dup; p.Glu333_385dup) in all patients. Recombinant mutant (rm)VWF only presented as a dimer. Co-expressed with wild-type VWF, the multimer pattern was indistinguishable from patients' plasma VWF. Immunofluorescence studies indicated retention of rmVWF in unusually large intracellular granules in the endoplasmic reticulum. ADAMTS-13 proteolysis of rmVWF under denaturing conditions was normal; however, an aberrant proteolytic fragment was apparent. A decreased ratio of VWF propeptide to VWF:Ag and a 1-desamino-8-d-arginine vasopressin (DDAVP) test in one patient indicated delayed VWF clearance, which was supported by clearance data after

Testosterone and acute stress are associated with fibrinogen and von Willebrand factor in African men: the SABPA study.

PubMed

Malan, Nicolaas T; von Känel, Roland; Schutte, Alta E; Huisman, Hugo W; Schutte, Rudolph; Smith, Wayne; Mels, Carina M; Kruger, Ruan; Meiring, Muriel; van Rooyen, Johannes M; Malan, Leoné

2013-10-12

Low testosterone, acute and chronic stress and hypercoagulation are all associated with hypertension and hypertension-related diseases. The interaction between these factors and future risk for coronary artery disease in Africans has not been fully elucidated. In this study, associations of testosterone, acute cardiovascular and coagulation stress responses with fibrinogen and von Willebrand factor in African and Caucasian men in a South African cohort were investigated. Cardiovascular variables were studied by means of beat-to-beat and ambulatory blood pressure monitoring. Fasting serum-, salivary testosterone and citrate coagulation markers were obtained from venous blood samples. Acute mental stress responses were evoked with the Stroop test. The African group demonstrated a higher cardiovascular risk compared to Caucasian men with elevated blood pressure, low-grade inflammation, chronic hyperglycemia (HbA1c), lower testosterone levels, and elevated von Willebrand factor (VWF) and fibrinogen levels. Blunted testosterone acute mental stress responses were demonstrated in African males. In multiple regression analyses, higher circulating levels of fibrinogen and VWF in Africans were associated with a low T environment (R(2) 0.24-0.28; p≤0.01), but only circulating fibrinogen in Caucasians. Regarding endothelial function, a low testosterone environment and a profile of augmented α-adrenergic acute mental stress responses (diastolic BP, D-dimer and testosterone) were associated with circulating VWF levels in Africans (Adj R(2) 0.24; p<0.05). An interdependence between acute mental stress, salivary testosterone, D-dimer and vascular responses existed in African males in their association with circulating VWF but no interdependence of the independent variables occurred with fibrinogen levels. © 2013.

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

Bleeding score in type 1 von Willebrand disease patients using the condensed MCMDM-1 vWD validated questionnaire.

PubMed

Pathare, A; Al Hajri, F; Al Omrani, S; Al Obaidani, N; Al Balushi, B; Al Falahi, K

2018-05-13

Assessment of the severity of bleeding symptom has led to the evolution of bleeding assessment tools which are now validated. To administer the condensed molecular and clinical markers for the diagnosis and management of type 1 von Willebrand disease VWD (MCMDM-1 vWD) questionnaire to the Omani type 1 vWD patients and correlate it with the laboratory parameters. Patients and controls were personally interviewed and the condensed MCMDM-1 vWD questionnaire administered by a single investigator. Bleeding score (BS) was calculated, based on the presence or absence of the bleeding symptoms according to a standard validated questionnaire in both the patients and the controls. The median age of the patient cohort was 27 (range, 7-49) years with 60.87% of females. The median time to administer condensed MCMDM-1 BS questionnaire was 11 minutes (interquartile range-IQR;7,16). Overall, bleeding from the oral cavity was the most predominant symptom (63%). The median BS was 5 (IQR;1,8) although individual scores ranged between 0 and 29. However, there was no statistically significant difference in BS between genders (males: median 4; IQR 1,6 and females: median 5, IQR 1,10) (P > .05, Kruskal-Wallis test) The Spearman's correlation value of BS was weak with FVIII:C levels and von Willebrand Ristocetin co-factor activity; very weak with von Willebrand Antigen level, and moderate with vonWillebrand Collagen Binding activity being -0.29, -0.28, -0.14 and -0.43, respectively. The BS reflects the severity of bleeding among the vWD patients. Although the BS was abnormal, it did not correlate significantly with the surrogate laboratory parameters [P > .05]. © 2018 John Wiley & Sons Ltd.

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

PubMed

Favaloro, Emmanuel J

2016-05-01

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.

Thrombin-dependent Incorporation of von Willebrand Factor into a Fibrin Network*

PubMed Central

Miszta, Adam; Pelkmans, Leonie; Lindhout, Theo; Krishnamoorthy, Ganeshram; de Groot, Philip G.; Hemker, Coenraad H.; Heemskerk, Johan W. M.; Kelchtermans, Hilde; de Laat, Bas

2014-01-01

Attachment of platelets from the circulation onto a growing thrombus is a process involving multiple platelet receptors, endothelial matrix components, and coagulation factors. It has been indicated previously that during a transglutaminase reaction activated factor XIII (FXIIIa) covalently cross-links von Willebrand factor (VWF) to polymerizing fibrin. Bound VWF further recruits and activates platelets via interactions with the platelet receptor complex glycoprotein Ib (GPIb). In the present study we found proof for binding of VWF to a fibrin monomer layer during the process of fibrinogen-to-fibrin conversion in the presence of thrombin, arvin, or a snake venom from Crotalus atrox. Using a domain deletion mutant we demonstrated the involvement of the C domains of VWF in this binding. Substantial binding of VWF to fibrin monomers persisted in the presence of the FXIIIa inhibitor K9-DON, illustrating that cross-linking via factor XIII is not essential for this phenomenon and suggesting the identification of a second mechanism through which VWF multimers incorporate into a fibrin network. Under high shear conditions, platelets were shown to adhere to fibrin only if VWF had been incorporated. In conclusion, our experiments show that the C domains of VWF and the E domain of fibrin monomers are involved in the incorporation of VWF during the polymerization of fibrin and that this incorporation fosters binding and activation of platelets. Fibrin thus is not an inert end product but partakes in further thrombus growth. Our findings help to elucidate the mechanism of thrombus growth and platelet adhesion under conditions of arterial shear rate. PMID:25381443

Congenital Type III von Willebrand's disease unmasked by hypothyroidism in a Shetland sheepdog.

PubMed

Scuderi, Margaret; Bessey, Lauren; Snead, Elisabeth; Burgess, Hilary; Carr, Anthony

2015-09-01

A 7-year-old, spayed female Shetland sheepdog had sudden onset of right-sided epistaxis. Diagnostic tests revealed Type III von Willebrand's disease and primary hypothyroidism leading to an acute hypothyroid crisis and acquired factor VIII (FVIII) deficiency. Levothyroxine therapy normalized the serum thyroxine and FVIII concentrations. The delayed onset of disease and the reversible FVIII deficiency that was corrected with levothyroxine therapy, support a role for hypothyroidism in the pathogenesis of this dog's sudden bleeding tendency as has been seen with hypothyroidism in humans.

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.

Von Willebrand factor-containing factor VIII concentrates and inhibitors in haemophilia A. A critical literature review.

PubMed

Franchini, Massimo; Lippi, Giuseppe

2010-11-01

The development of inhibitors that neutralise the function of factor VIII (FVIII) is currently not only the most challenging complication associated with the treatment of haemophilia A but it also increases the disease-related morbidity as bleeding episodes do not respond to standard therapy. The main short-term goal of the treatment of inhibitor patients is to control bleeding episodes while the long-term one is to permanently eradicate the inhibitor by immune tolerance induction, particularly in the case of high-titer antibodies. Due to some in vitro studies and clinical observations, some investigators have suggested that FVIII concentrates containing von Willebrand factor (VWF) may be less immunogenic than high-purity or recombinant FVIII products. It has also been suggested that success rates for immune tolerance induction are higher when plasma-derived FVIII products are used. The currently available data from laboratory and clinical studies on the role of VWF in inhibitor development and eradication in haemophilia A is critically analysed in this review. As a result, we have not found definitive evidence supporting a role for product type on inhibitor incidence and inhibitor eradication in haemophilia A patients.

Bleeding symptoms and laboratory correlation in patients with severe von Willebrand disease.

PubMed

Metjian, A D; Wang, C; Sood, S L; Cuker, A; Peterson, S M; Soucie, J M; Konkle, B A

2009-07-01

Type 3 von Willebrand disease (VWD) is a rare bleeding disorder with markedly decreased or absent von Willebrand factor (VWF) protein, accompanied by a parallel decrease in VWF function and factor VIII (FVIII) activity. The goal of this study was to describe the population of patients enrolled in the USA Centers for Disease Control Universal Data Collection (UDC) study with type 3 VWD, defined as a VWF:Ag of <10%, and to correlate bleeding symptoms with VWF and FVIII levels. Data on 150 patients were analysed. Almost all patients experienced bleeding episodes (98%) and required blood and/or factor product treatment (92%). While oral mucosal bleeding (the site of first bleed in 54%) was most common, subsequent muscle and joint bleeds were also seen (28%, 45%, respectively), and intracranial haemorrhage occurred in 8% of individuals. Mean age of first bleed was lower in those with either a FVIII < or =5% or a VWF:Ag <1%. Univariate marginal model analysis showed lower levels of FVIII and VWF:Ag both predicted a higher risk of joint bleeding. Longitudinal multivariate analysis found a lower FVIII level (P = 0.03), increasing age (P < 0.0001), history of joint bleeding (P = 0.001), higher body mass index (BMI) (P < 0.0001), and use of home infusion (P = 0.02) were all negatively associated with joint mobility. Low levels of VWF:Ag (P = 0.003) and male sex (P = 0.007) were also negatively associated with joint function. This study documents the strong bleeding phenotype in severe VWD and provides data to help target therapy, including prophylaxis, for patients most at risk of bleeding complications.

Outcome of laparoscopic ovariohysterectomy or ovariectomy in dogs with von Willebrand disease or factor VII deficiency: 20 cases (2012-2014).

PubMed

Keeshen, Thomas P; Case, J Brad; Runge, Jeffrey J; Singh, Ameet; Mayhew, Philipp D; Steffey, Michele A; Culp, William T N

2017-11-01

OBJECTIVE To describe surgical techniques and perioperative management of dogs with von Willebrand disease (VWD) or factor VII (FVII) deficiency undergoing laparoscopic ovariohysterectomy or ovariectomy and evaluate outcomes. DESIGN Retrospective case series. ANIMALS 20 client-owned dogs with VWD (n = 16) or FVII deficiency (4). PROCEDURES Dogs with VWD or FVII deficiency that underwent laparoscopic ovariohysterectomy or ovariectomy between 2012 and 2014 were retrospectively identified via a multi-institutional review of medical records. RESULTS Median expression of von Willebrand factor was 19% (interquartile range, 18% to 30%). All 16 dogs with VWD were Doberman Pinschers, and all were pretreated with desmopressin; 4 also received cryoprecipitate. One of 4 dogs with FVII deficiency received plasma preoperatively, and 1 was treated with desmopressin; 2 dogs received no preoperative treatment. Laparoscopic ovariectomy was performed in 9 dogs with VWD and 2 dogs with FVII deficiency, laparoscopic ovariectomy with gastropexy was performed in 6 dogs with VWD and 1 dog with FVII deficiency, and laparoscopic-assisted ovariohysterectomy was performed in 1 dog with VWD and 1 dog with FVII deficiency. Iatrogenic splenic laceration requiring conversion to laparotomy occurred during trocar insertion in 1 dog with VWD. No postoperative complications, including signs of hemorrhage, were reported for any dogs. CONCLUSIONS AND CLINICAL RELEVANCE Laparoscopic ovariohysterectomy or ovariectomy in dogs with VWD or FVII deficiency pretreated with desmopressin, cryoprecipitate, or plasma transfusions were not associated with clinical signs of hemorrhage, suggesting that minimally invasive ovariohysterectomy or ovariectomy may be considered in female dogs affected with these coagulopathies.

Association of von Willebrand factor blood levels with exercise hypertension.

PubMed

Nikolic, Sonja B; Adams, Murray J; Otahal, Petr; Edwards, Lindsay M; Sharman, James E

2015-05-01

A hypertensive response to moderate intensity exercise (HRE) is associated with increased cardiovascular risk. The mechanisms of an HRE are unclear, although previous studies suggest this may be due to haemostatic and/or haemodynamic factors. We investigated the relationships between an HRE with haemostatic and hemodynamic indices. Sixty-four participants (57 ± 10 years, 71 % male) with indication for exercise stress testing underwent cardiovascular assessment at rest and during moderate intensity exercise, from which 20 participants developed an HRE (defined as moderate exercise systolic BP ≥ 170 mmHg/men and ≥ 160 mmHg/women). Rest, exercise and post-exercise blood samples were analysed for haemostatic markers, including von Willebrand factor (vWf), and haemodynamic measures of brachial and central blood pressure (BP), aortic stiffness and systemic vascular resistance index (SVRi). HRE participants had higher rest vWf compared with normotensive response to exercise (NRE) participants (1,927 mU/mL, 95 % CI 1,240-2,615, vs. 1,129 mU/mL, 95 % CI 871-1,386; p = 0.016). vWf levels significantly decreased from rest to post-exercise in HRE participants (p = 0.005), whereas vWf levels significantly increased from rest to exercise in NRE participants (p = 0.030). HRE participants also had increased triglycerides, rest BP, aortic stiffness and exercise SVRi (p < 0.05 for all). Rest vWf predicted exercise brachial systolic BP (β = 0.220, p = 0.043; adjusted R (2) = 0.451, p < 0.001) independent of age, sex, body mass index, triglycerides, rest brachial systolic BP and aortic stiffness. Increased rest blood levels of vWf are independently associated with moderate intensity exercise systolic BP. These findings implicate abnormalities in haemostasis as a possible factor contributing to HRE at moderate intensity.

Thermodynamic analysis of the interaction of factor VIII with von Willebrand factor.

PubMed

Dimitrov, Jordan D; Christophe, Olivier D; Kang, Jonghoon; Repessé, Yohann; Delignat, Sandrine; Kaveri, Srinivas V; Lacroix-Desmazes, Sébastien

2012-05-22

Factor VIII (FVIII) is a glycoprotein that plays an important role in the intrinsic pathway of coagulation. In circulation, FVIII is protected upon binding to von Willebrand factor (VWF), a chaperone molecule that regulates its half-life, distribution, and activity. Despite the biological significance of this interaction, its molecular mechanisms are not fully characterized. We determined the equilibrium and activation thermodynamics of the interaction between FVIII and VWF. The equilibrium affinity determined by surface plasmon resonance was temperature-dependent with a value of 0.8 nM at 35 °C. The FVIII-VWF interaction was characterized by very fast association (8.56 × 10(6) M(-1) s(-1)) and fast dissociation (6.89 × 10(-3) s(-1)) rates. Both the equilibrium association and association rate constants, but not the dissociation rate constant, were dependent on temperature. Binding of FVIII to VWF was characterized by favorable changes in the equilibrium and activation entropy (TΔS° = 89.4 kJ/mol, and -TΔS(++) = -8.9 kJ/mol) and unfavorable changes in the equilibrium and activation enthalpy (ΔH° = 39.1 kJ/mol, and ΔH(++) = 44.1 kJ/mol), yielding a negative change in the equilibrium Gibbs energy. Binding of FVIII to VWF in solid-phase assays demonstrated a high sensitivity to acidic pH and a sensitivity to ionic strength. Our data indicate that the interaction between FVIII and VWF is mediated mainly by electrostatic forces, and that it is not accompanied by entropic constraints, suggesting the absence of conformational adaptation but the presence of rigid "pre-optimized" binding surfaces.

Von Willebrand Factor Gene Variants Associate with Herpes simplex Encephalitis.

PubMed

Abdelmagid, Nada; Bereczky-Veress, Biborka; Atanur, Santosh; Musilová, Alena; Zídek, Václav; Saba, Laura; Warnecke, Andreas; Khademi, Mohsen; Studahl, Marie; Aurelius, Elisabeth; Hjalmarsson, Anders; Garcia-Diaz, Ana; Denis, Cécile V; Bergström, Tomas; Sköldenberg, Birgit; Kockum, Ingrid; Aitman, Timothy; Hübner, Norbert; Olsson, Tomas; Pravenec, Michal; Diez, Margarita

2016-01-01

Herpes simplex encephalitis (HSE) is a rare complication of Herpes simplex virus type-1 infection. It results in severe parenchymal damage in the brain. Although viral latency in neurons is very common in the population, it remains unclear why certain individuals develop HSE. Here we explore potential host genetic variants predisposing to HSE. In order to investigate this we used a rat HSE model comparing the HSE susceptible SHR (Spontaneously Hypertensive Rats) with the asymptomatic infection of BN (Brown Norway). Notably, both strains have HSV-1 spread to the CNS at four days after infection. A genome wide linkage analysis of 29 infected HXB/BXH RILs (recombinant inbred lines-generated from the prior two strains), displayed variable susceptibility to HSE enabling the definition of a significant QTL (quantitative trait locus) named Hse6 towards the end of chromosome 4 (160.89-174Mb) containing the Vwf (von Willebrand factor) gene. This was the only gene in the QTL with both cis-regulation in the brain and included several non-synonymous SNPs (single nucleotide polymorphism). Intriguingly, in human chromosome 12 several SNPs within the intronic region between exon 43 and 44 of the VWF gene were associated with human HSE pathogenesis. In particular, rs917859 is nominally associated with an odds ratio of 1.5 (95% CI 1.11-2.02; p-value = 0.008) after genotyping in 115 HSE cases and 428 controls. Although there are possibly several genetic and environmental factors involved in development of HSE, our study identifies variants of the VWF gene as candidates for susceptibility in experimental and human HSE.

Von Willebrand Factor Gene Variants Associate with Herpes simplex Encephalitis

PubMed Central

Atanur, Santosh; Musilová, Alena; Zídek, Václav; Saba, Laura; Warnecke, Andreas; Khademi, Mohsen; Studahl, Marie; Aurelius, Elisabeth; Hjalmarsson, Anders; Garcia-Diaz, Ana; Denis, Cécile V.; Bergström, Tomas; Sköldenberg, Birgit; Kockum, Ingrid; Aitman, Timothy; Hübner, Norbert; Olsson, Tomas; Pravenec, Michal; Diez, Margarita

2016-01-01

Herpes simplex encephalitis (HSE) is a rare complication of Herpes simplex virus type-1 infection. It results in severe parenchymal damage in the brain. Although viral latency in neurons is very common in the population, it remains unclear why certain individuals develop HSE. Here we explore potential host genetic variants predisposing to HSE. In order to investigate this we used a rat HSE model comparing the HSE susceptible SHR (Spontaneously Hypertensive Rats) with the asymptomatic infection of BN (Brown Norway). Notably, both strains have HSV-1 spread to the CNS at four days after infection. A genome wide linkage analysis of 29 infected HXB/BXH RILs (recombinant inbred lines—generated from the prior two strains), displayed variable susceptibility to HSE enabling the definition of a significant QTL (quantitative trait locus) named Hse6 towards the end of chromosome 4 (160.89–174Mb) containing the Vwf (von Willebrand factor) gene. This was the only gene in the QTL with both cis-regulation in the brain and included several non-synonymous SNPs (single nucleotide polymorphism). Intriguingly, in human chromosome 12 several SNPs within the intronic region between exon 43 and 44 of the VWF gene were associated with human HSE pathogenesis. In particular, rs917859 is nominally associated with an odds ratio of 1.5 (95% CI 1.11–2.02; p-value = 0.008) after genotyping in 115 HSE cases and 428 controls. Although there are possibly several genetic and environmental factors involved in development of HSE, our study identifies variants of the VWF gene as candidates for susceptibility in experimental and human HSE. PMID:27224245

Inhibitory activity of aspirin on von Willebrand factor-induced platelet aggregation.

PubMed

Homoncik, M; Jilma, B; Eichelberger, B; Panzer, S

2000-09-01

The effect of aspirin (ASA) on vWF induced platelet - platelet interaction is unknown. We therefore tested the response of platelets to von Willebrand factor (vWF) coated beads induced platelet aggregation before and after i.v. and oral ASA. 1000 mg ASA was infused to 10 healthy individuals and after a wash-out period 7 volunteers received 100 mg ASA orally over a period of 11 days. Prior to ASA and in regular intervals thereafter we tested the reactivity to vWF-coated beads to assess platelet adhesion/aggregation and the fade-out time of ASA effects on platelets. Considerable interindividual variability in response to vWF-coated beads was observed, both before ASA and after treatment with ASA. The maximal response to vWF-coated beads (Tmax), the time lag, and the slope of the curve were significantly affected by i.v. ASA, whereas 100 mg of ASA had only inconstant effect on Tmax and slope. The absolute reduction of Tmax after ASA depended on the pre-ASA level, while the percentage of the reduction was similar in all individuals. Thus, platelet aggregation induced by vWF-coated beads is impaired by ASA. Furthermore, our data indicate a large interindividual variability of the response to ASA shortly after treatment induction, which becomes more constant after prolonged treatment.

Establishment and characterization of a new and stable collagen-binding assay for the assessment of von Willebrand factor activity

PubMed Central

Ni, Y; Nesrallah, J; Agnew, M; Geske, F J; Favaloro, E J

2013-01-01

Introduction Laboratory diagnosis of von Willebrand disease (VWD) requires determination of both von Willebrand factor (VWF) protein levels and activity. Current VWF activity tests include the ristocetin cofactor assay and the collagen-binding assay (VWF:CB). The goal of this investigation is to characterize a new collagen-binding assay and to determine its effectiveness in identifying VWD. Methods Analytical studies were carried out to characterize the performance of a new VWF:CB ELISA. Additionally, samples from a normal population were tested as were well-characterized type 1 and type 2 VWD samples. Results Repeatability and within-laboratory precision studies resulted in coefficients of variation (CVs) of ≤11%. A linear range of 1–354% (0.01–3.54 IU/mL) was determined, along with a limit of detection and a lower limit of quantitation of 1.6% and 4.0% (0.016 and 0.04 IU/mL), respectively. Samples tested from apparently healthy individuals resulted in a normal range of 54–217% (0.54–2.17 IU/mL). Known VWD type 1 and type 2 samples were also analyzed by the ELISA, with 99% of samples having VWF:CB below the normal reference range and an estimated 96% sensitivity and 87% specificity using a VWF collagen-binding/antigen cutoff ratio of 0.50. Conclusion This new VWF:CB ELISA provides an accurate measure of collagen-binding activity that aids in the diagnosis and differentiation of type 1 from type 2 VWD. PMID:23107512

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.

von Willebrand factor and factor VIII are independently required to form stable occlusive thrombi in injured veins

PubMed Central

Chauhan, Anil K.; Kisucka, Janka; Lamb, Colin B.; Bergmeier, Wolfgang

2007-01-01

von Willebrand factor (VWF) protects factor VIII (FVIII) from proteolysis and mediates the initial contact of platelets with the injured vessel wall, thus playing an important role in hemostasis and thrombosis. VWF is crucial for the formation of occlusive thrombi at arterial shear rates. However, with only a few conflicting studies published, the role of VWF in venous thrombosis is still unclear. Using gene-targeted mice, we show that in ferric chloride–injured veins platelet adhesion to subendothelium is decreased and thrombus growth is impaired in VWF−/− mice when compared with wild type (WT). We also observed increased embolization in the VWF−/− mice, which was due to lower FVIII levels in these mice as recombinant factor VIII (r-FVIII) restored thrombus stability. Despite normalization of blood clotting time and thrombus stability after r-FVIII infusion, the VWF−/− venules did not occlude. Transgenic platelets lacking the VWF receptor GPIbα extracellular domain showed decreased adhesion to injured veins. But, after a delay, all the injured venules occluded in these transgenic mice. Thus, VWF likely uses other adhesion receptors besides GPIbα in thrombus growth under venous shear conditions. Our studies document crucial roles for VWF and FVIII in experimental thrombosis under venous flow conditions in vivo. PMID:17119108

Autoregulation of von Willebrand factor function by a disulfide bond switch

PubMed Central

Butera, Diego; Passam, Freda; Ju, Lining; Cook, Kristina M.; Woon, Heng; Aponte-Santamaría, Camilo; Gardiner, Elizabeth; Davis, Amanda K.; Murphy, Deirdre A.; Bronowska, Agnieszka; Luken, Brenda M.; Baldauf, Carsten; Jackson, Shaun; Andrews, Robert; Gräter, Frauke; Hogg, Philip J.

2018-01-01

Force-dependent binding of platelet glycoprotein Ib (GPIb) receptors to plasma von Willebrand factor (VWF) plays a key role in hemostasis and thrombosis. Previous studies have suggested that VWF activation requires force-induced exposure of the GPIb binding site in the A1 domain that is autoinhibited by the neighboring A2 domain. However, the biochemical basis of this “mechanopresentation” remains elusive. From a combination of protein chemical, biophysical, and functional studies, we find that the autoinhibition is controlled by the redox state of an unusual disulfide bond near the carboxyl terminus of the A2 domain that links adjacent cysteine residues to form an eight-membered ring. Only when the bond is cleaved does the A2 domain bind to the A1 domain and block platelet GPIb binding. Molecular dynamics simulations indicate that cleavage of the disulfide bond modifies the structure and molecular stresses of the A2 domain in a long-range allosteric manner, which provides a structural explanation for redox control of the autoinhibition. Significantly, the A2 disulfide bond is cleaved in ~75% of VWF subunits in healthy human donor plasma but in just ~25% of plasma VWF subunits from heart failure patients who have received extracorporeal membrane oxygenation support. This suggests that the majority of plasma VWF binding sites for platelet GPIb are autoinhibited in healthy donors but are mostly available in heart failure patients. These findings demonstrate that a disulfide bond switch regulates mechanopresentation of VWF. PMID:29507883

Autoregulation of von Willebrand factor function by a disulfide bond switch.

PubMed

Butera, Diego; Passam, Freda; Ju, Lining; Cook, Kristina M; Woon, Heng; Aponte-Santamaría, Camilo; Gardiner, Elizabeth; Davis, Amanda K; Murphy, Deirdre A; Bronowska, Agnieszka; Luken, Brenda M; Baldauf, Carsten; Jackson, Shaun; Andrews, Robert; Gräter, Frauke; Hogg, Philip J

2018-02-01

Force-dependent binding of platelet glycoprotein Ib (GPIb) receptors to plasma von Willebrand factor (VWF) plays a key role in hemostasis and thrombosis. Previous studies have suggested that VWF activation requires force-induced exposure of the GPIb binding site in the A1 domain that is autoinhibited by the neighboring A2 domain. However, the biochemical basis of this "mechanopresentation" remains elusive. From a combination of protein chemical, biophysical, and functional studies, we find that the autoinhibition is controlled by the redox state of an unusual disulfide bond near the carboxyl terminus of the A2 domain that links adjacent cysteine residues to form an eight-membered ring. Only when the bond is cleaved does the A2 domain bind to the A1 domain and block platelet GPIb binding. Molecular dynamics simulations indicate that cleavage of the disulfide bond modifies the structure and molecular stresses of the A2 domain in a long-range allosteric manner, which provides a structural explanation for redox control of the autoinhibition. Significantly, the A2 disulfide bond is cleaved in ~75% of VWF subunits in healthy human donor plasma but in just ~25% of plasma VWF subunits from heart failure patients who have received extracorporeal membrane oxygenation support. This suggests that the majority of plasma VWF binding sites for platelet GPIb are autoinhibited in healthy donors but are mostly available in heart failure patients. These findings demonstrate that a disulfide bond switch regulates mechanopresentation of VWF.

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

PubMed Central

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.

2014-01-01

Summary 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. PMID:23702511

Molecular and clinical profile of von Willebrand disease in Spain (PCM-EVW-ES): comprehensive genetic analysis by next-generation sequencing of 480 patients

PubMed Central

Borràs, Nina; Batlle, Javier; Pérez-Rodríguez, Almudena; López-Fernández, María Fernanda; Rodríguez-Trillo, Ángela; Lourés, Esther; Cid, Ana Rosa; Bonanad, Santiago; Cabrera, Noelia; Moret, Andrés; Parra, Rafael; Mingot-Castellano, María Eva; Balda, Ignacia; Altisent, Carme; Pérez-Montes, Rocío; Fisac, Rosa María; Iruín, Gemma; Herrero, Sonia; Soto, Inmaculada; de Rueda, Beatriz; Jiménez-Yuste, Víctor; Alonso, Nieves; Vilariño, Dolores; Arija, Olga; Campos, Rosa; Paloma, María José; Bermejo, Nuria; Berrueco, Rubén; 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; Vidal, Francisco; Corrales, Irene

2017-01-01

Molecular diagnosis of patients with von Willebrand disease is pending in most populations due to the complexity and high cost of conventional molecular analyses. The need for molecular and clinical characterization of von Willebrand disease in Spain prompted the creation of a multicenter project (PCM-EVW-ES) that resulted in the largest prospective cohort study of patients with all types of von Willebrand disease. Molecular analysis of relevant regions of the VWF, including intronic and promoter regions, was achieved in the 556 individuals recruited via the development of a simple, innovative, relatively low-cost protocol based on microfluidic technology and next-generation sequencing. A total of 704 variants (237 different) were identified along VWF, 155 of which had not been previously recorded in the international mutation database. The potential pathogenic effect of these variants was assessed by in silico analysis. Furthermore, four short tandem repeats were analyzed in order to evaluate the ancestral origin of recurrent mutations. The outcome of genetic analysis allowed for the reclassification of 110 patients, identification of 37 asymptomatic carriers (important for genetic counseling) and re-inclusion of 43 patients previously excluded by phenotyping results. In total, 480 patients were definitively diagnosed. Candidate mutations were identified in all patients except 13 type 1 von Willebrand disease, yielding a high genotype-phenotype correlation. Our data reinforce the capital importance and usefulness of genetics in von Willebrand disease diagnostics. The progressive implementation of molecular study as the first-line test for routine diagnosis of this condition will lead to increasingly more personalized and effective care for this patient population. PMID:28971901

Beneficial Effects of High-Density Lipoproteins on Acquired von Willebrand Syndrome in Aortic Valve Stenosis.

PubMed

Gebhard, C; Maafi, F; Stähli, B E; Bonnefoy, A; Gebhard, C E; Nachar, W; de Oliveira Moraes, A Benjamim; Mecteau, M; Mihalache-Avram, T; Lavoie, V; Kernaleguen, A E; Shi, Y; Busseuil, D; Chabot-Blanchet, M; Perrault, L P; Rhainds, D; Rhéaume, E; Tardif, J C

2018-02-01

 Infusions of apolipoprotein A-I (apoA-I), the major protein component of high-density lipoproteins (HDL), result in aortic valve stenosis (AVS) regression in experimental models. Severe AVS can be complicated by acquired von Willebrand syndrome, a haemorrhagic disorder associated with loss of high-molecular-weight von Willebrand factor (vWF) multimers (HMWM), the latter being a consequence of increased shear stress and enhanced vWF-cleaving protease (ADAMTS-13) activity. Although antithrombotic actions of HDL have been described, its effects on ADAMTS-13 and vWF in AVS are unknown.  We assessed ADAMTS-13 activity in plasma derived from a rabbit model of AVS ( n  = 29) as well as in plasma collected from 64 patients with severe AVS (age 65.0 ± 10.4 years, 44 males) undergoing aortic valve replacement (AVR). In both human and rabbit AVS plasma, ADAMTS-13 activity was higher than that in controls ( p  < 0.05). Accordingly, AVS patients had less HMWM than controls (66.3 ± 27.2% vs. 97.2 ± 24.1%, p  < 0.0001). Both ADAMTS-13 activity and HMWM correlated significantly with aortic transvalvular gradients, thereby showing opposing correlations ( r  = 0.3, p  = 0.018 and r  = -0.4, p  = 0.003, respectively). Administration of an apoA-I mimetic peptide reduced ADAMTS-13 activity in AVS rabbits as compared with the placebo group (2.0 ± 0.5 RFU/sec vs. 3.8 ± 0.4 RFU/sec, p  < 0.05). Similarly, a negative correlation was found between ADAMTS-13 activity and HDL cholesterol levels in patients with AVS ( r  = -0.3, p  = 0.045).  Our data indicate that HDL levels are associated with reduced ADAMTS-13 activity and increased HMWM. HDL-based therapies may reduce the haematologic abnormalities of the acquired von Willebrand syndrome in AVS. Schattauer GmbH Stuttgart.

Effects of moderate-intensity physical exercise on pharmacokinetics of factor VIII and von Willebrand factor in young adults with severe haemophilia A: a pilot study.

PubMed

Zourikian, N; Merlen, C; Bonnefoy, A; St-Louis, J; Rivard, G E

2016-05-01

In persons with severe haemophilia A (pwshA), infused factor VIII (FVIII) half-life can vary according to such determinants as blood group, von Willebrand factor (VWF) level or age; however, FVIII pharmacokinetics (PK) has not been well studied in pwshA during exercise. To investigate FVIII PK in pwshA performing moderate-intensity aerobic exercise. Twelve young-adult pwshA with the intron-22 inversion mutation, on relatively low-dose FVIII prophylaxis regimens, and relatively good musculoskeletal status were recruited. Abbreviated PK of FVIII activity and von Willebrand factor antigen (VWF:Ag) level were compared - during rest, and with 60-min exercise (2 × 15 min each of moderate-intensity stationary cycling and treadmill walking). During rest and exercise visits, a baseline blood specimen was drawn, routine prophylaxis FVIII infused; then six blood specimens were taken over the following 24 h. For all subjects, mean half-life of infused FVIII did not change significantly with exercise vs. at rest (577 ± 190 vs. 614 ± 163 min; P = 0.4131). VWF:Ag rose transiently by 40-50% for 6-8 h with exercise (P < 0.01), particularly in non-O blood group subjects. No musculoskeletal bleeds occurred during the study. Four × 15 min of moderate-intensity aerobic exercise increased VWF:Ag levels for 6-8 h, and showed no evidence of accelerated FVIII clearance or of musculoskeletal bleeding in these young-adult pwshA with relatively good musculoskeletal status, on relatively low-dose FVIII prophylaxis regimens. However, O blood group impact would merit larger studies, with longer durations of similar or more vigorous exercise intensities. © 2016 John Wiley & Sons Ltd.

Rapid activation of endothelial cells enables P. falciparum adhesion to platelet decorated von Willebrand factor strings

PubMed Central

Bridges, Daniel J.; Bunn, James; van Mourik, Jan A.; Grau, Georges; Preston, Roger J.S.; Molyneux, Malcolm; Combes, Valery; O'Donnell, James S.; de Laat, Bas; Craig, Alister

2009-01-01

During Plasmodium falciparum malaria infections, von Willebrand factor (VWF) levels are elevated, post-mortem studies show platelets co-localised with sequestered infected erythrocytes (IE) at brain microvascular sites, while in vitro studies have demonstrated platelet-mediated IE adhesion to TNF-activated brain endothelium via a bridging mechanism. This current study demonstrates how all these observations could be linked through a completely novel mechanism whereby IE adhere via platelet decorated ultra-large VWF strings on activated endothelium. Using an in vitro laminar flow model, we have demonstrated tethering and firm adhesion of IE to the endothelium specifically at sites of platelet accumulation. We also show that an IE pro-adhesive state, capable of supporting high levels of binding within minutes of induction can be removed through the action of the VWF protease ADAMTS-13. We propose that this new mechanism contributes to sequestration both independently of and in concert with current adhesion mechanisms. PMID:19897581

Modifying murine von Willebrand factor A1 domain for in vivo assessment of human platelet therapies.

PubMed

Chen, Jianchun; Tan, Kui; Zhou, Hairu; Lo, Hsuan-Fu; Tronik-Le Roux, Diana; Liddington, Robert C; Diacovo, Thomas G

2008-01-01

The A1 domain of von Willebrand factor (VWF-A1) plays a crucial role in hemostasis and thrombosis by initiating platelet adhesion at sites of arterial injury through interactions with the platelet receptor glycoprotein Ib alpha (GPIbalpha). Here we report that murine VWF-A1 supports limited binding of human platelets. However, atomic models of GPIbalpha-VWF-A1 complexes identified an electrostatic 'hot-spot' that, when mutated in murine VWF-A1, switches its binding specificity from mouse to human GPIbalpha. Furthermore, mice expressing this mutant VWF-A1 display a bleeding phenotype that can be corrected by infusion of human platelets. Mechanistically, human platelets correct the phenotype by forming occlusive thrombi, an event that can be abrogated by blockade of GPIbalpha or by the preadministration of inhibitors of platelet activation or adhesion (clopidogrel (Plavix) and abciximab (ReoPro), respectively). Thus, by modifying a protein interface, we have generated a potential biological platform for preclinical screening of antithrombotics that specifically target human platelets.

Native-like aggregates of Factor VIII (FVIII) are immunogenic von Willebrand Factor deficient and hemophilia A mice

PubMed Central

Pisal, Dipak S.; Kosloski, Matthew P.; Middaugh, C. Russell; Bankert, Richard B.; Balu-Iyer, Sathy V.

2013-01-01

The administration of recombinant Factor VIII (FVIII) is the first line therapy for Hemophilia A (HA), but 25–35% of patients develop an inhibitory antibody response. In general, the presence of aggregates contributes to unwanted immunogenic responses against therapeutic proteins. FVIII has been shown to form both native-like and non-native aggregates. Previously, we showed that non-native aggregates of FVIII are less immunogenic compared to the native protein. Here we investigated the effect of native-like aggregates of FVIII on immunogenicity in HA and von Willebrand Factor knockout (vWF−/−) mice. Mice immunized with native-like aggregates showed significantly higher inhibitory antibody titers compared to animals that received native FVIII. Following re-stimulation in vitro with native FVIII, the activation of CD4+ T cells isolated from mice immunized with native-like aggregates is ~4 fold higher than mice immunized with the native protein. Furthermore, this is associated with increases in the secretion of pro-inflammatory cytokines IL-6 and IL-17 in the native-like aggregate treatment group. The results indicate that the native-like aggregates of FVIII are more immunogenic than native FVIII for both the B cell and T cell responses. PMID:22388918

Molecular and clinical profile of von Willebrand disease in Spain (PCM-EVW-ES): comprehensive genetic analysis by next-generation sequencing of 480 patients.

PubMed

Borràs, Nina; Batlle, Javier; Pérez-Rodríguez, Almudena; López-Fernández, María Fernanda; Rodríguez-Trillo, Ángela; Lourés, Esther; Cid, Ana Rosa; Bonanad, Santiago; Cabrera, Noelia; Moret, Andrés; Parra, Rafael; Mingot-Castellano, María Eva; Balda, Ignacia; Altisent, Carme; Pérez-Montes, Rocío; Fisac, Rosa María; Iruín, Gemma; Herrero, Sonia; Soto, Inmaculada; de Rueda, Beatriz; Jiménez-Yuste, Víctor; Alonso, Nieves; Vilariño, Dolores; Arija, Olga; Campos, Rosa; Paloma, María José; Bermejo, Nuria; Berrueco, Rubén; 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; Vidal, Francisco; Corrales, Irene

2017-12-01

Molecular diagnosis of patients with von Willebrand disease is pending in most populations due to the complexity and high cost of conventional molecular analyses. The need for molecular and clinical characterization of von Willebrand disease in Spain prompted the creation of a multicenter project (PCM-EVW-ES) that resulted in the largest prospective cohort study of patients with all types of von Willebrand disease. Molecular analysis of relevant regions of the VWF , including intronic and promoter regions, was achieved in the 556 individuals recruited via the development of a simple, innovative, relatively low-cost protocol based on microfluidic technology and next-generation sequencing. A total of 704 variants (237 different) were identified along VWF , 155 of which had not been previously recorded in the international mutation database. The potential pathogenic effect of these variants was assessed by in silico analysis. Furthermore, four short tandem repeats were analyzed in order to evaluate the ancestral origin of recurrent mutations. The outcome of genetic analysis allowed for the reclassification of 110 patients, identification of 37 asymptomatic carriers (important for genetic counseling) and re-inclusion of 43 patients previously excluded by phenotyping results. In total, 480 patients were definitively diagnosed. Candidate mutations were identified in all patients except 13 type 1 von Willebrand disease, yielding a high genotype-phenotype correlation. Our data reinforce the capital importance and usefulness of genetics in von Willebrand disease diagnostics. The progressive implementation of molecular study as the first-line test for routine diagnosis of this condition will lead to increasingly more personalized and effective care for this patient population. Copyright© 2017 Ferrata Storti Foundation.

Increased active von Willebrand factor during disease development in the aging diabetic patient population.

PubMed

Chen, Shuang Feng; Xia, Zuo Li; Han, Ji Ju; Wang, Yi Ting; Wang, Ji Yue; Pan, Shao Dong; Wu, Ya Ping; Zhang, Bin; Li, Guang Yao; Du, Jing Wei; Gao, Hen Qiang; de Groot, Philip G; de Laat, Bas; Hollestelle, Martine J

2013-02-01

Type 2 diabetes is known to cause endothelial activation resulting in the secretion of von Willebrand factor (VWF). We have shown that levels of VWF in a glycoprotein Ib-binding conformation are increased in specific clinical settings. The aim of the current study is to investigate whether active VWF levels increase during aging and the development of diabetes within the population of patients suffering from type 2 diabetes. Patients and controls were divided into two groups based on age: older and younger than 60 years of age. VWF antigen, VWF propeptide, VWF activation factor and total active VWF were measured. Patients older than 60 years of age had increased levels of total active VWF, VWF activation factor and VWF propeptide compared to younger patients and controls. All measured VWF parameters were associated with age in diabetic patients. Total active VWF and VWF propeptide correlated with the period of being diagnosed with diabetes. Regression analyses showed that especially the VWF activation factor was strongly associated with diabetes in patients older than 60 years of age. In conclusion, we found that the conformation of VWF could be involved in the disease process of diabetes and that the VWF in a glycoprotein Ib-binding conformation could play a role as risk marker during the development of diabetes in combination with an increase in age. Our study shows that the active quality of VWF was more important than the quantity.

Elevated plasma factor VIII enhances venous thrombus formation in rabbits: contribution of factor XI, von Willebrand factor and tissue factor.

PubMed

Sugita, Chihiro; Yamashita, Atsushi; Matsuura, Yunosuke; Iwakiri, Takashi; Okuyama, Nozomi; Matsuda, Shuntaro; Matsumoto, Tomoko; Inoue, Osamu; Harada, Aya; Kitazawa, Takehisa; Hattori, Kunihiro; Shima, Midori; Asada, Yujiro

2013-07-01

Elevated plasma levels of factor VIII (FVIII) are associated with increased risk of deep venous thrombosis. The aim of this study is to elucidate how elevated FVIII levels affect venous thrombus formation and propagation in vivo. We examined rabbit plasma FVIII activity, plasma thrombin generation, whole blood coagulation, platelet aggregation and venous wall thrombogenicity before and one hour after an intravenous infusion of recombinant human FVIII (rFVIII). Venous thrombus induced by the endothelial denudation of rabbit jugular veins was histologically assessed. Thrombus propagation was evaluated as indocyanine green fluorescence intensity. Argatroban, a thrombin inhibitor, and neutralised antibodies for tissue factor (TF), factor XI (FXI), and von Willebrand factor (VWF) were infused before or after thrombus induction to investigate their effects on venous thrombus formation or propagation. Recombinant FVIII (100 IU/kg) increased rabbit plasma FVIII activity two-fold and significantly enhanced whole blood coagulation and total plasma thrombin generation, but did not affect initial thrombin generation time, platelet aggregation and venous wall thrombogenicity. The rFVIII infusion also increased the size of venous thrombus 1 hour after thrombus induction. Argatroban and the antibodies for TF, FXI or VWF inhibited such enhanced thrombus formation and all except TF suppressed thrombus propagation. In conclusion, elevated plasma FVIII levels enhance venous thrombus formation and propagation. Excess thrombin generation by FXI and VWF-mediated FVIII recruitment appear to contribute to the growth of FVIII-driven venous thrombus.

Comparative study on collagen-binding enzyme-linked immunosorbent assay and ristocetin cofactor activity assays for detection of functional activity of von Willebrand factor.

PubMed

Turecek, Peter L; Siekmann, Jürgen; Schwarz, Hans Peter

2002-04-01

For more than two decades, the ristocetin cofactor (RCo) assay, which measures the von Willebrand factor (vWF)-mediated agglutination of platelets in the presence of the antibiotic ristocetin, has been the most common method for measuring the functional activity of vWF. There is, however, general agreement among clinical analysts that this method has major practical disadvantages in performance and reproducibility. Today, collagen-binding assays (CBA) based on the enzyme-linked immunosorbent assay (ELISA) technique that measure the interaction of vWF and collagen are an alternative analytic procedure based on a more physiological function than that of the RCo procedure. We used both assay systems in a comparative study to assess the functional activity of vWF in plasma as well as in therapeutic preparations. We measured RCo activities of plasma from healthy donors and patients with different types of von Willebrand disease (vWD) and of vWF as a drug substance in factor (F) VIII/vWF concentrates using both the aggregometric and the macroscopic methods. In addition, we measured collagen-binding activity (vWF:CB) using a recently developed commercially available CBA system. To investigate the relation between the structure and the functional activity of vWF, we isolated vWF species with different numbers of multimers from FVIII/vWF concentrates by affinity chromatography on immobilized heparin. The vWF:RCo and vWF:CB of the different fractions were measured, and the multimeric structure of vWF was analyzed by sodium dodecyl sulfate (SDS) agarose gel electrophoresis. (vWF:CB and vWF:RCo are part of the nomenclature proposed by the International Society on Thrombosis and Hemostasis Scientific and Standardization Committee [ISTH SSC] subcommittee on von Willebrand factor, in Maastricht, Germany, June 16, 2000.) Measurement of functional vWF activity by CBA can be carried out with substantially higher interassay reproducibility than can measurement of RCo. Both assay

Laboratory diagnosis of von Willebrand disease type 1/2E (2A subtype IIE), type 1 Vicenza and mild type 1 caused by mutations in the D3, D4, B1-B3 and C1-C2 domains of the von Willebrand factor gene. Role of von Willebrand factor multimers and the von Willebrand factor propeptide/antigen ratio.

PubMed

Gadisseur, Alain; Berneman, Zwi; Schroyens, Wilfried; Michiels, Jan Jacques

2009-01-01

Autosomal dominant von Willebrand disease (VWD) type 1/2E is a quantitative/qualitative defect in the von Willebrand factor (VWF) caused by heterozygous cysteine and non-cysteine mutations in the D3 domain of the VWF gene and results in a secretion-multimerization-clearance defect in mutant VWF with the loss of large VWF multimers not due to proteolysis. The multimers of patients with dominant VWD type 1/2E due to mutations in the D3 domain show an aberrant triplet structure with lack of outer bands but with pronounced inner bands of the triplet structure combined with a relative decrease in large multimers reflecting heterozygosity for multimerization defects. There is a good response to desmopressin (DDAVP) followed by rapid clearance of VWF:antigen (Ag), factor VIII coagulant activity (FVIII:C) and VWF:ristocetin cofactor activity (RCo) as the main cause of VWD type 1 or 2 with typical 2E multimeric pattern (VWD type 1/2E). Cysteine mutations in the D3 domains (C1130, C1149 and C1190) show pronounced features of VWD 1/2E with the relative loss of large and relative increase in small VWF multimers with abnormal triplet structure in heterozygotes. Such abnormalities are less pronounced in patients with a milder form of VWD type 1 due to non-cysteine mutations W1144G, T1156M and W1120S in the D3 domain. VWD type 1 Vicenza is caused by the R1205H mutation in the D3 domain and characterized by equally low levels of FVIII:C, VWF:Ag and VWF:RCo. The response to DDAVP in VWD Vicenza is good for FVIII:C, VWF:Ag and VWF:RCo, which is followed by a rapid clearance in less than a few hours of FVIII:C and VWF parameters. The ratios for FVIII:C/VWF:Ag, VWF:RCo/Ag and VWF:CB/Ag remain normal before and after DDAVP indicating that VWD Vicenza clearly differs from VWD type 1, 1/2E and 2M. A new set of missense mutations in D4, B1-B3 and C1-C2 domains has been discovered as the cause of a mild VWD type 1 secretion defect with normal VWF multimers or smeary VWF multimeric pattern

Clinical usefulness of a functional assay for the von Willebrand factor cleaving protease (ADAMTS 13) and its inhibitor in a patient with thrombotic thrombocytopenic purpura.

PubMed

Rick, M E; Austin, H; Leitman, S F; Krizek, D M; Aronson, D L

2004-02-01

Decreased von Willebrand factor cleaving protease activity (VWFCP, ADAMTS 13) leads to persistence of unusually large multimers of von Willebrand factor that bind to platelets, causing platelet aggregates, microangiopathic hemolysis, and thrombocytopenia in patients with thrombotic thrombocytopenic purpura (TTP). The clinical value of measuring ADAMTS 13 and its inhibitor is not fully defined; the case reported here illustrates the usefulness of the assay to help confirm the clinical diagnosis in a patient with other potential causes for thrombotic microangiopathy; the assay also helped in making treatment decisions. A patient with systemic lupus erythematosis (SLE) presented with fever and abdominal pain, thrombocytopenia, and anemia. Thrombotic microangiopathy was diagnosed by the appearance of schistocytes, decreasing platelet count, and evidence of hemolysis. ADAMTS 13 was decreased and an inhibitor was demonstrated in the patient's initial blood sample within 24 hr of admission. Plasma exchange was initiated, and serial assays showed increased ADAMTS 13 activity and decreased inhibitor after each plasma exchange; there was a rebound in inhibitor and a decrease in ADAMTS 13 activity prior to the next exchange that lessened over time. Increasing levels of protease activity correlated with clinical and laboratory improvement. Measurement of ADAMTS 13 activity and its inhibitor aided in the diagnosis of this complicated case of a patient with other potential causes for microangiopathic hemolysis. Subsequent levels correlated with the clinical course, and disappearance of the inhibitor indicated that long-term plasma exchange or other immunosuppressive treatment was not needed.

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

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. © 2014 John Wiley & Sons Ltd.

Coats' disease, Turner syndrome, and von Willebrand disease in a patient with Wildtype Norrie disease pseudoglioma.

PubMed

Desai, Rajen U; Saffra, Norman A; Krishna, Rati P; Rosenberg, Steven E

2011-01-01

The authors describe a girl diagnosed as having Coats' disease, Turner syndrome (45X karyotype), and type 1 von Willebrand disease. She tested negative for the Norrie disease pseudoglioma (NDP) gene located on the X-chromosome, which has been suspected of contributing to Coats' disease. Copyright 2010, SLACK Incorporated.

Increased metastatic potential of tumor cells in von Willebrand factor-deficient mice.

PubMed

Terraube, V; Pendu, R; Baruch, D; Gebbink, M F B G; Meyer, D; Lenting, P J; Denis, C V

2006-03-01

The key role played by von Willebrand factor (VWF) in platelet adhesion suggests a potential implication in various pathologies, where this process is involved. In cancer metastasis development, tumor cells interact with platelets and the vessel wall to extravasate from the circulation. As a potential mediator of platelet-tumor cell interactions, VWF could influence this early step of tumor spread and therefore play a role in cancer metastasis. To investigate whether VWF is involved in metastasis development. In a first step, we characterized the interaction between murine melanoma cells B16-BL6 and VWF in vitro. In a second step, an experimental metastasis model was used to compare the formation of pulmonary metastatic foci in C57BL/6 wild-type and VWF-null mice following the injection of B16-BL6 cells or Lewis lung carcinoma cells. In vitro adhesion assays revealed that VWF is able to promote a dose-dependent adhesion of B16-BL6 cells via its Arg-Gly-Asp (RGD) sequence. In the experimental metastasis model, we found a significant increase in the number of pulmonary metastatic foci in VWF-null mice compared with the wild-type mice, a phenotype that could be corrected by restoring VWF plasma levels. We also showed that increased survival of the tumor cells in the lungs during the first 24 h in the absence of VWF was the cause of this increased metastasis. These findings suggest that VWF plays a protective role against tumor cell dissemination in vivo. Underlying mechanisms remain to be investigated.

Genetics of von Willebrand disease type 1.

PubMed

Riddel, James P; Aouizerat, Bradley E

2006-10-01

The most common form of von Willebrand disease (VWD) is reported to be type 1, accounting for as much as 80% of reported cases. With prevalence estimates as high as 1.6% in the general population, upwards of 4.5 million Americans may be affected. Unfortunately, VWD type 1 is also the most difficult type to diagnose. Despite the continuing progress in defining the genetic lesions responsible for VWD types 2 and 3, identification of the genetic determinants of VWD type 1 remains elusive. Herein the phenomenon known as VWD is summarized, the challenges associated with the diagnosis of type 1 VWD are described, and the role of genetic research in meeting these challenges is explored. The authors identify key gaps in the current genetics literature and suggest new avenues for future research. Lastly, they explore the role of nurses in this research and clinical endeavor. To the authors'knowledge, this review is the first to address these complex issues in nursing research.

Syringomyelia following surgery for a spontaneous spinal subdural hematoma in a 13-year-old girl with congenital von Willebrand disease: case report and literature review.

PubMed

Ben Nsir, A; Boubaker, A; Jemel, H

2016-04-01

Spontaneous spinal subdural hematomas are rare. Their occurrence in a child with congenital von Willebrand disease and the complication of their surgery by a large secondary syringomyelia have never been previously reported. A 13-year-old girl with congenital von Willebrand disease presented to our emergency department in January 2011 for sudden onset of severe back pain centered in her thoracic spine rapidly aggravated by signs of acute myelopathy without any precipitating factor. MRI scan revealed a thoracic subdural collection anterior to the spinal cord at the T7-T9 level, hyperintense on T1- and T2-weighted sequences consistent with an acute spinal subdural hemorrhage. Evacuation of the subdural hematoma was realized immediately after hemostasis parameter correction, and post-operative course was uneventful with full functional recovery. One year later, the patient presented once again but with progressive and more severe myelopathy caused by a large syringomyelia extending from the T5 level to the conus medullaris. A syringopleural shunting was performed and the patient was unrolled under an intensive care and rehabilitation program. Her condition remarkably improved and she became able to walk independently within 2 weeks post-operatively. von Willebrand disease should be included as a possible factor of spontaneous spinal subdural hemorrhage. Surgery is advised in emergency and can be associated with remarkable recovery especially in children. Delayed syringomyelia can complicate the post-operative course and can be successfully addressed by syringopleural shunting. Long-term clinical and radiological follow-up is advocated.

Endothelial markers in malignant vascular tumours of the liver: superiority of QB-END/10 over von Willebrand factor and Ulex europaeus agglutinin 1.

PubMed

Anthony, P P; Ramani, P

1991-01-01

A new monoclonal antibody, QB-END/10, raised against the CD34 antigen in human endothelial cell membranes and haemopoietic progenitor cells, was studied for its usefulness as a marker of neoplastic vascular cells in 21 angiosarcomas and seven malignant haemangioendotheliomas of the liver. QB-END/10 was both more sensitive and more specific than Von Willebrand factor (VWF) and Ulex europaeus 1 agglutinin (UEA-1) in labelling endothelial cells and it did not cross react with epithelia as UEA-1 often does. Staining was uniformly strong and clear in all histological variants of these two tumours. QB-END/10 should prove particularly useful in the differential diagnosis of malignant vascular tumours of the liver.

Endothelial markers in malignant vascular tumours of the liver: superiority of QB-END/10 over von Willebrand factor and Ulex europaeus agglutinin 1.

PubMed Central

Anthony, P P; Ramani, P

1991-01-01

A new monoclonal antibody, QB-END/10, raised against the CD34 antigen in human endothelial cell membranes and haemopoietic progenitor cells, was studied for its usefulness as a marker of neoplastic vascular cells in 21 angiosarcomas and seven malignant haemangioendotheliomas of the liver. QB-END/10 was both more sensitive and more specific than Von Willebrand factor (VWF) and Ulex europaeus 1 agglutinin (UEA-1) in labelling endothelial cells and it did not cross react with epithelia as UEA-1 often does. Staining was uniformly strong and clear in all histological variants of these two tumours. QB-END/10 should prove particularly useful in the differential diagnosis of malignant vascular tumours of the liver. Images PMID:1705261

Antifibrinolytic therapy for preventing oral bleeding in patients with haemophilia or Von Willebrand disease undergoing minor oral surgery or dental extractions.

PubMed

van Galen, Karin P M; Engelen, Eveline T; Mauser-Bunschoten, Evelien P; van Es, Robert J J; Schutgens, Roger E G

2015-12-24

Minor oral surgery or dental extractions (oral or dental procedures) are widely performed and can be complicated by hazardous oral bleeding, especially in people with an inherited bleeding disorder such as haemophilia or Von Willebrand disease. The amount and severity of singular bleedings depend on disease-related factors, such as the severity of the haemophilia, both local and systemic patient factors (such as periodontal inflammation, vasculopathy or platelet dysfunction) and intervention-related factors (such as the type and number of teeth extracted or the dimension of the wound surface). Similar to local haemostatic measures and suturing, antifibrinolytic therapy is a cheap, safe and potentially effective treatment to prevent bleeding complications in individuals with bleeding disorders undergoing oral or dental procedures. However, a systematic review of trials reporting outcomes after oral surgery or a dental procedure in people with an inherited bleeding disorder, with or without, the use of antifibrinolytic agents has not been performed to date. The primary objective was to assess the efficacy of local or systemic use of antifibrinolytic agents to prevent bleeding complications in people with haemophilia or Von Willebrand disease undergoing oral or dental procedures. Secondary objectives were to assess if antifibrinolytic agents can replace or reduce the need for clotting factor concentrate therapy in people with haemophilia or Von Willebrand disease and to further establish the effects of these agents on bleeding in oral or dental procedures for each of these populations. We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Coagulopathies Trials Register, compiled from electronic database searches of the Cochrane Central Register of Controlled Trials (CENTRAL), of MEDLINE and from handsearching of journals and conference abstract books. We additionally searched the reference lists of relevant articles and reviews. We searched Pub

Exercise-induced shear stress is associated with changes in plasma von Willebrand factor in older humans.

PubMed

Gonzales, Joaquin U; Thistlethwaite, John R; Thompson, Benjamin C; Scheuermann, Barry W

2009-07-01

Shear stress is the frictional force of blood against the endothelium, a stimulus for endothelial activation and the release of von Willebrand factor (vWF). This study tested the hypothesis that the increase in shear stress associated with exercise correlates with plasma vWF. Young (n = 14, 25.7 +/- 5.4 years) and older (n = 13, 65.6 +/- 10.7 years) individuals participated in 30 min of dynamic handgrip exercise at a moderate intensity. Brachial artery diameter and blood flow were measured using ultrasound Doppler and blood samples were collected before, immediately after, and following 30 min of recovery from exercise with plasma levels of vWF. Plasma levels of vWF increased (P < 0.05) by 6 +/- 2% in young individuals and 4 +/- 1% in older individuals immediately after exercise. The change in plasma vWF was linearly correlated with the increase in shear stress during exercise in older individuals (post-exercise: r = 0.78, 30 min recovery: r = 0.77, P < 0.01), but no association was found in the young individuals. These changes in plasma levels of vWF in humans suggest that aging influences endothelial activation and hemostasis.

Cyclical thrombocytosis, acquired von Willebrand syndrome and aggressive non-melanoma skin cancers are common in patients with Philadelphia-negative myeloproliferative neoplasms treated with hydroxyurea.

PubMed

Verner, Emma; Forsyth, Cecily; Grigg, Andrew

2014-05-01

Abstract Cyclical thrombocytosis, acquired von Willebrand syndrome, aggressive non-melanoma skin cancers and other hydroxyurea complications have been reported in Philadelphia-negative myeloproliferative neoplasms (MPNs), but their incidence and clinical consequences have not been defined in a large cohort of patients. We conducted a retrospective analysis of 188 consecutive patients with MPNs specifically addressing the incidence of these complications. Cyclical thrombocytosis was documented in 29 patients (15%), the majority of whom were receiving hydroxyurea. Acquired von Willebrand syndrome was identified in 17 of the 84 screened patients (20%), but was not associated with any major bleeding complications. Non-melanoma skin cancers were reported in 51 patients (27%). Hydroxyurea-related fever occurred in nine of 149 patients (6%) who received hydroxyurea. Seventy-three patients (39%) experienced a total of 98 major thrombotic events, with the majority of these occurring prior to or within 3 months of the diagnosis. Cyclical thrombocytosis, acquired von Willebrand syndrome, aggressive non-melanoma skin cancers and other hydroxyurea-related complications are not infrequent in MPNs and have important clinical consequences for management.

Joint bleeds in von Willebrand disease patients have significant impact on quality of life and joint integrity: a cross-sectional study.

PubMed

van Galen, K P M; Sanders, Y V; Vojinovic, U; Eikenboom, J; Cnossen, M H; Schutgens, R E G; van der Bom, J G; Fijnvandraat, K; Laros-Van Gorkom, B A P; Meijer, K; Leebeek, F W G; Mauser-Bunschoten, E P

2015-05-01

Joint bleeds (JB) are reported in a minority of patients with von Willebrand disease (VWD) but may lead to structural joint damage. Prevalence, severity and impact of JB in VWD are largely unknown. The aim of this study was to assess JB prevalence, onset, treatment and impact on health-related quality of life (HR-QoL) and joint integrity in moderate and severe VWD. In the Willebrand in the Netherlands study 804 moderate and severe VWD patients [von Willebrand factor (VWF) activity ≤30U dL(-1)] completed a questionnaire on occurrence, sites and consequences of JB. To analyse JB number, onset, treatment and impact on joint integrity we additionally performed a patient-control study on medical file data comparing patients with JB to age, gender, factor VIII (FVIII)- and VWF activity matched VWD patients without JB. Of all VWD patients 23% (184/804) self-reported JB. These 184 patients reported joint damage more often (54% vs. 18%, P < 0.001) and had lower HR-QoL (SF36, P < 0.05) compared to VWD patients not reporting JB. Of 55 patients with available JB data, 65% had the first JB before age 16. These 55 patients used more clotting factor concentrate (CFC; median dose 43 vs. 0 IE FVIII kg(-1) year(-1) , P < 0.001), more often had X-ray joint damage (44% vs. 11%, P = 0.001] and chronic joint pain (44% vs. 18%, P = 0.008) compared to 55 control VWD patients without JB. In conclusion, joint bleeds are reported by 23% of moderate and severe VWD patients, mostly start in childhood, are associated with more CFC use, joint pain, lower HR-QoL and significantly more radiological and self-reported joint damage. © 2015 John Wiley & Sons Ltd.

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

PubMed

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

2016-05-23

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.

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.

Exercise induced von Willebrand Factor release -- new model for routine endothelial testing.

PubMed

Balen, Sanja; Ruzić, Alen; Mirat, Jure; Persić, Viktor

2007-01-01

Endothelial dysfunction (ED) is actively involved in the mechanism of occurrence, development and progression of all the degrees of atherosclerosis. The established impact of ED on the progress and outcome of cardiovascular diseases, together with convincing indications of a possible successful therapeutic modification, necessitate the changeover of ED assessment from experimental to a routine practice. As there is no appropriate method for a clinical practice, scientists anticipate significant research efforts in the further development. Among numerous methods already available, von Willebrand Factor (vWF) stands out significantly. In accordance with the accepted leading diagnostic role of vWF baseline levels in the group of peripheral endothelial markers, and earlier scientific observations on the absence of its expected reactivation during physical exercise, we hypothesised this promising theory. We believe that a constant stronger release of vWF in endothelial cell injury leads to the exhaustion of its stores in Weibel-Palade bodies with the consequent absence of the expected rise of concentration during the exercise. Therefore, we hypothesised that ED could be exhaustible vWF endothelopathy and the exercise induced release of vWF a new, simple, safe and reliable test for the detection of ED and monitoring of the expected therapeutic effect. In order to have a final clinical usability of the proposed diagnostic model, it is necessary to test its reliability in different pathological and risk states, and establish susceptibility in therapeutic procedures. The correlation with invasive functional angiographic tests and the flow mediated dilatation test of peripheral arteries also needs to be validated. We expect the proposed test of vWF inducibility to find its place in clinical practice, i.e. in prevention, prediction and therapy of cardiovascular diseases.

Paradoxical Effect of Nonphysiological Shear Stress on Platelets and von Willebrand Factor.

PubMed

Chen, Zengsheng; Mondal, Nandan K; Ding, Jun; Koenig, Steven C; Slaughter, Mark S; Wu, Zhongjun J

2016-07-01

Blood can become hypercoagulable by shear-induced platelet activation and generation of microparticles. It has been reported that nonphysiological shear stress (NPSS) could induce shedding of platelet receptor glycoprotein (GP) Ibα, which may result in an opposite effect to hemostasis. The aim of this study was to investigate the influence of the NPSS on platelets and von Willebrand factor (vWF). Human blood was exposed to two levels of NPSS (25 Pa, 125 Pa) with an exposure time of 0.5 s, generated by using a novel blood-shearing device. Platelet activation (P-selectin expression, GPIIb/IIIa activation and generation of microparticles) and shedding of three platelet receptors (GPIbα, GPVI, GPIIb/IIIa) in sheared blood were quantified using flow cytometry. Aggregation capacity of sheared blood induced by ristocetin and collagen was evaluated using an aggregometer. Shear-induced vWF damage was characterized with Western blotting. Consistent with the published data, the NPSS caused significantly more platelets to become activated with increasing NPSS level. Meanwhile, the NPSS induced the shedding of platelet receptors. The loss of the platelet receptors increased with increasing NPSS level. The aggregation capacity of sheared blood induced by ristocetin and collagen decreased. There was a loss of high molecular weight multimers (HMWMs) of vWF in sheared blood. These results suggest that the NPSS induced a paradoxical effect. More activated platelets increase the risk of thrombosis, while the reduction in platelet receptors and the loss of HMWM-vWF increased the propensity of bleeding. The finding might provide a new perspective to understand thrombosis and acquired bleeding disorder in patients supported with blood contacting medical devices. Copyright © 2015 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

A Common Variant in the Von Willebrand Factor Gene is Associated With Multiple Functional Consequences

PubMed Central

Vaidya, Dhananjay; Yanek, Lisa R.; Herrera-Galeano, J. Enrique; Mathias, Rasika A.; Moy, Taryn F.; Faraday, Nauder; Becker, Lewis C.; Becker, Diane M.

2010-01-01

Von Willebrand Factor (vWF) is a plasma protein involved in thrombosis and hemostasis [1]. We examined whether common single nucleotide polymorphisms (SNPs) in the vWF gene were associated with vWF levels and platelet aggregation-related functional consequences in1230 Whites and 837 African Americans in a cross-sectional family based genetic study of platelet function. From a high-density scan, 28 SNPs with a minor allele frequency > 5% in both races were tested for association using age and sex adjusted variance components analysis in MERLIN. SNP rs216321, with the strongest association with vWF levels in biracial metaanalysis (p=9.5×10−6, Whites–p=8.1×10−4, African Americans–p=3.6×10−3), encoding a R852Q substitution in the D’D3 protein domain, demonstrated negative association with plasma vWF. The R852Q variant was recessively associated with 15.5% lower collagen-induced platelet aggregation adjusting for dose-response relationship (p=0.010, vWF-level adjusted p=0.003). Each copy of the R852Q variant was additively associated with 31% higher FVIII levels (p=0.039, vWF-adjusted p=0.033). In conclusion, this common missense polymorphism appears to have pleiotropic functional consequences. PMID:20941784

The thrombospondin-1 N700S polymorphism is associated with early myocardial infarction without altering von Willebrand factor multimer size.

PubMed

Zwicker, Jeffrey I; Peyvandi, Flora; Palla, Roberta; Lombardi, Rossana; Canciani, Maria Teresa; Cairo, Andrea; Ardissino, Diego; Bernardinelli, Luisa; Bauer, Kenneth A; Lawler, Jack; Mannucci, Pier

2006-08-15

The N700S polymorphism of thrombospondin-1 (TSP-1) has been identified as a potential genetic risk factor for myocardial infarction (MI). In a large case-control study of 1425 individuals who survived a myocardial infarction prior to age 45, the N700S polymorphism was a significant risk factor for myocardial infarction in both homozygous (odds ratio [OR] 1.9, 95% confidence interval [CI] 1.1-3.3, P = .01) and heterozygous carriers of the S700 allele (OR 1.4, 95% CI 1.1-3.3, P = .01). TSP-1 has been shown to reduce von Willebrand factor (VWF) multimer size, and the domain responsible for VWF-reducing activity has been localized to the calcium-binding C-terminal sequence. As the N700S polymorphism was previously shown to alter the function of this domain, we investigated whether the altered VWF-reducing activity of TSP-1 underlies the observed prothrombotic phenotype. The TSP1 N700S polymorphism did not influence VWF multimer size in patients homozygous for either allele nor was there a significant reduction of VWF multimer size following incubation with recombinant N700S fragments or platelet-derived TSP-1.

The thrombospondin-1 N700S polymorphism is associated with early myocardial infarction without altering von Willebrand factor multimer size

PubMed Central

Zwicker, Jeffrey I.; Peyvandi, Flora; Palla, Roberta; Lombardi, Rossana; Canciani, Maria Teresa; Cairo, Andrea; Ardissino, Diego; Bernardinelli, Luisa; Bauer, Kenneth A.; Lawler, Jack; Mannucci, Pier

2006-01-01

The N700S polymorphism of thrombospondin-1 (TSP-1) has been identified as a potential genetic risk factor for myocardial infarction (MI). In a large case-control study of 1425 individuals who survived a myocardial infarction prior to age 45, the N700S polymorphism was a significant risk factor for myocardial infarction in both homozygous (odds ratio [OR] 1.9, 95% confidence interval [CI] 1.1-3.3, P = .01) and heterozygous carriers of the S700 allele (OR 1.4, 95% CI 1.1-3.3, P = .01). TSP-1 has been shown to reduce von Willebrand factor (VWF) multimer size, and the domain responsible for VWF-reducing activity has been localized to the calcium-binding C-terminal sequence. As the N700S polymorphism was previously shown to alter the function of this domain, we investigated whether the altered VWF-reducing activity of TSP-1 underlies the observed prothrombotic phenotype. The TSP1 N700S polymorphism did not influence VWF multimer size in patients homozygous for either allele nor was there a significant reduction of VWF multimer size following incubation with recombinant N700S fragments or platelet-derived TSP-1. PMID:16684956

Refrigeration-Induced Binding of von Willebrand Factor Facilitates Fast Clearance of Refrigerated Platelets.

PubMed

Chen, Wenchun; Druzak, Samuel A; Wang, Yingchun; Josephson, Cassandra D; Hoffmeister, Karin M; Ware, Jerry; Li, Renhao

2017-12-01

Apheresis platelets for transfusion treatment are currently stored at room temperature because after refrigeration platelets are rapidly cleared on transfusion. In this study, the role of von Willebrand factor (VWF) in the clearance of refrigerated platelets is addressed. Human and murine platelets were refrigerated in gas-permeable bags at 4°C for 24 hours. VWF binding, platelet signaling events, and platelet post-transfusion recovery and survival were measured. After refrigeration, the binding of plasma VWF to platelets was drastically increased, confirming earlier studies. The binding was blocked by peptide OS1 that bound specifically to platelet glycoprotein (GP)Ibα and was absent in VWF - / - plasma. Although surface expression of GPIbα was reduced after refrigeration, refrigeration-induced VWF binding under physiological shear induced unfolding of the GPIbα mechanosensory domain on the platelet, as evidenced by increased exposure of a linear epitope therein. Refrigeration and shear treatment also induced small elevation of intracellular Ca 2+ , phosphatidylserine exposure, and desialylation of platelets, which were absent in VWF -/- platelets or inhibited by OS1, which is a monomeric 11-residue peptide (CTERMALHNLC). Furthermore, refrigerated VWF -/- platelets displayed increased post-transfusion recovery and survival than wild-type ones. Similarly, adding OS1 to transgenic murine platelets expressing only human GPIbα during refrigeration improved their post-transfusion recovery and survival. Refrigeration-induced binding of VWF to platelets facilitates their rapid clearance by inducing GPIbα-mediated signaling. Our results suggest that inhibition of the VWF-GPIbα interaction may be a potential strategy to enable refrigeration of platelets for transfusion treatment. © 2017 American Heart Association, Inc.

Paradoxical Effect of Non-Physiological Shear Stress on Platelets and von Willebrand factor

PubMed Central

Chen, Zengsheng; Mondal, Nandan K; Ding, Jun; Koenig, Steven C.; Slaughter, Mark S.; Wu, Zhongjun J.

2016-01-01

Blood can become hypercoagulable by shear-induced platelet activation and generation of microparticles. It has been reported that non-physiological shear stress (NPSS) could induce shedding of platelet receptor glycoprotein (GP) Ibα, which may result in an opposite effect to hemostasis. The aim of this study was to investigate the influence of the NPSS on platelets and von Willebrand factor (vWF). Human blood was exposed to two levels of NPSS (25Pa, 125Pa) with an exposure time of 0.5 sec., generated by using a novel blood shearing device. Platelet activation (P-selectin expression, GPIIb/IIIa activation and generation of microparticles) and shedding of three platelet receptors (GPIbα, GPVI, GPIIb/IIIa) in sheared blood were quantified using flow cytometry. Aggregation capacity of sheared blood induced by ristocetin and collagen was evaluated using an aggregometer. Shear-induced vWF damage was characterized with western blotting. Consistent with the published data, the NPSS caused significantly more platelets to become activated with increasing NPSS level. Meanwhile, the NPSS induced the shedding of platelet receptors. The loss of the platelet receptors increased with increasing NPSS level. The aggregation capacity of sheared blood induced by ristocetin and collagen decreased. There was a loss of high molecular weight multimers (HMWM) of vWF in sheared blood. These results suggest that the NPSS induced a paradoxical effect. More activated platelets increase the risk of thrombosis while the reduction in platelet receptors and the loss of HMWM-vWF increased the propensity of bleeding. The finding might provide a new perspective to understand thrombosis and acquired bleeding disorder in patients supported with blood contacting medical devices. PMID:26582038

Association of ABO blood groups with von Willebrand factor, factor VIII and ADAMTS-13 in patients with lung cancer.

PubMed

Liu, Xia; Chen, Xiaogang; Yang, Jiezuan; Guo, Renyong

2017-09-01

Coagulative and fibrinolytic disorders appear to be associated with the development of lung cancer. The aim of the present study was to determine plasma levels of von Willebrand factor (VWF) and a disintegrin and metalloproteinase with a thrombospondin type 1 motif 13 (ADAMTS-13), and factor VIII (FVIII) activity, in association with O and non-O blood groups in patients with lung cancer. Plasma levels of VWF and ADAMTS-13, and FVIII activity were measured in 115 patients with lung cancer and 98 healthy subjects. Phenotyping of the ABO blood groups was also performed for the two groups. Significantly increased VWF levels and FVIII activity, as well as significantly decreased ADAMTS-13 levels, were observed in patients with distant metastasis as compared with those without distant metastasis and the healthy controls. Plasma VWF levels and FVIII activity were significantly increased in subjects with non-O type blood compared with those with type O blood in the two groups. However, a significant decrease in ADAMTS-13 levels was observed only in the control group among those with non-O type blood, compared with those with type O blood. The results of the present study indicate that increased VWF and decreased ADAMTS-13 levels facilitate the invasiveness and metastasis of lung cancer. Non-O blood groups constitute a risk factor for increased VWF and FVIII in plasma. Continued monitoring of VWF and ADAMTS-13 levels, and of FVIII activity in patients with lung cancer with distinct blood groups may help to minimize the incidence of thrombotic events and improve assessment of disease progression.

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.

Interaction of von Willebrand factor domains with collagen investigated by single molecule force spectroscopy

NASA Astrophysics Data System (ADS)

Posch, Sandra; Obser, Tobias; König, Gesa; Schneppenheim, Reinhard; Tampé, Robert; Hinterdorfer, Peter

2018-03-01

von Willebrand factor (VWF) is a huge multimeric protein that plays a key role in primary hemostasis. Sites for collagen binding, an initial event of hemostasis, are located in the VWF-domains A1 and A3. In this study, we investigated single molecule interactions between collagen surfaces and wild type VWF A1A2A3 domain constructs, as well as clinically relevant VWF A3 domain point mutations, such as p.Ser1731Thr, p.Gln1734His, and p.His1786Arg. For this, we utilized atomic force microscopy based single molecular force spectroscopy. The p.Ser1731Thr mutant had no impact on the VWF-collagen type III and VI interactions, while the p.Gln1734His and p.His1786Arg mutants showed a slight increase in bond stability to collagen type III. This effect probably arises from additional hydrogen bonds that come along with the introduction of these mutations. Using the same mutants, but collagen type VI as a binding partner, resulted in a significant increase in bond stability. VWF domain A1 was reported to be essential for the interaction with collagen type VI and thus our findings strengthen the hypothesis that the VWF A1 domain can compensate for mutations in the VWF A3 domain. Additionally, our data suggest that the mutations could even stabilize the interaction between VWF and collagen without shear. VWF-collagen interactions seem to be an important system in which defective interactions between one VWF domain and one type of collagen can be compensated by alternative binding events.

Use of routine histopathology and factor VIII-related antigen/von Willebrand factor immunohistochemistry to differentiate primary hemangiosarcoma of bone from telangiectatic osteosarcoma in 54 dogs.

PubMed

Giuffrida, M A; Bacon, N J; Kamstock, D A

2017-12-01

Hemangiosarcoma (HSA) of bone and telangiectatic osteosarcoma (tOSA) can appear similar histologically, but differ in histogenesis (malignant endothelial cells versus osteoblasts), and may warrant different treatments. Immunohistochemistry (IHC) for endothelial cell marker factor VIII-related antigen/von Willebrand factor (FVIII-RAg/vWF) is a well-documented ancillary test to confirm HSA diagnoses in soft tissues, but its use in osseous HSA is rarely described. Archived samples of 54 primary appendicular bone tumours previously diagnosed as HSA or tOSA were evaluated using combination routine histopathology (RHP) and IHC. Approximately 20% of tumours were reclassified on the basis of FVIII-RAg/vWF immunoreactivity, typically from an original diagnosis of tOSA to a reclassified diagnosis of HSA. No sample with tumour osteoid clearly identified on RHP was immunopositive for FVIII-RAg/vWF. RHP alone was specific but not sensitive for diagnosis of HSA, compared with combination RHP and IHC. Routine histopathological evaluation in combination with FVIII-RAg/vWF IHC can help differentiate canine primary appendicular HSA from tOSA. © 2016 John Wiley & Sons Ltd.

Effects of plasma glycosyltransferase on the ABO(H) blood group antigens of human von Willebrand factor.

PubMed

Kano, Taiki; Kondo, Kazunao; Hamako, Jiharu; Matsushita, Fumio; Sakai, Kazuya; Matsui, Taei

2018-04-04

Von Willebrand factor (VWF) is one of the plasma protein carrying ABO(H) blood group antigens, but the combining process of these antigens is not clear. In the present study, we examined whether plasma glycosyltransferase affects the blood group antigens on VWF. VWF expressing H-antigen (H-VWF) from blood group O and bovine serum albumin conjugated with H-antigen (H-BSA) were incubated with recombinant α1-3-N-acetylgalactosaminyltransferase (rA-transferase) and A-plasma with or without an additional UDP-GalNAc. Transformed antigens were detected by western blotting and ELISA, using an anti-A antibody. Both H-VWF and H-BSA acquired the A-antigen after incubation with rA-transferase and UDP-GalNAc. Incubation with A-plasma very weakly converted the H-antigen on BSA and VWF to A-antigen only in the presence of supplemented UDP-GalNAc. This conversion was enhanced on desialylation of H-VWF. These results indicate that sugar chains of plasma VWF can be modified by the external glycosyltransferase, but that plasma glycosyltransferase has no effect on the blood group antigens of VWF due to its low activity and the lack of donor sugars. Further, sialic acid residues of VWF may exert a protective effect against post-translational glycosylation. Our results clearly exclude the possibility that blood group antigens of VWF are constructed extracellularly in plasma.

E. coli derived Von Willebrand Factor-A2 domain FRET proteins that quantify ADAMTS13 activity

PubMed Central

Dayananda, Kannayakanahalli M.; Gogia, Shobhit; Neelamegham, Sriram

2010-01-01

The cleavage of the A2-domain of Von Willebrand Factor (VWF) by the metalloprotease ADAMTS13 regulates VWF size and platelet thrombosis rates. Reduction or inhibition of this enzyme activity leads to thrombotic thrombocytopenic purpura (TTP). We generated a set of novel molecules called VWF-A2 FRET proteins’, where variants of YFP (Venus) and CFP (Cerulean) flank either the entire VWF-A2 domain (175 amino acids) or truncated fragments (141, 113, 77 amino acids) of this domain. These proteins were expressed in E. coli in soluble form, and they exhibited Fluorescence/Förster Resonance Energy Transfer (FRET) properties. Results show that introduction of Venus/Cerulean itself did not alter the ability of VWF-A2 to undergo ADAMTS13 mediated cleavage. The smallest FRET protein, XS-VWF, detected plasma ADAMTS13 activity down to 10% of normal levels. Tests of acquired and inherited TTP could be completed within 30 min. VWF-A2 conformation changed progressively, and not abruptly, upon increasing urea concentration. While proteins with 77 and 113 VWF-A2 residues were cleaved in the absence of denaturant, 4M urea was required for the efficient cleavage of larger constructs. Overall, VWF-A2 FRET proteins can be applied both for the rapid diagnosis of plasma ADAMTS13 activity, and as a tool to study VWF-A2 conformation dynamics. PMID:21146487

Unconjugated Bilirubin Inhibits Proteolytic Cleavage of von Willebrand Factor by ADAMTS13 Protease

PubMed Central

Lu, Rui-Nan; Yang, Shangbin; Wu, Haifeng M.; Zheng, X. Long

2015-01-01

Summary Background Bilirubin is a yellow breakdown product of heme catabolism. Increased serum levels of unconjugated bilirubin are conditions commonly seen in premature neonates and adults with acute hemolysis including thrombotic microangiopathy. Previous studies have shown that unconjugated bilirubin lowers plasma ADAMTS13 activity, but the mechanism is not fully understood. Objectives The study is to determine whether unconjugated bilirubin directly inhibits the cleavage of von Willebrand factor (VWF) and its analogs by ADAMTS13. Methods Fluorogenic, SELDI-TOF mass spectrometric assay, and Western blotting analyses were employed to address this question. Results Unconjugated bilirubin inhibits the cleavage of F485-rVWF73-H, D633-rVWF73-H, and GST-rVWF71-11K by ADAMTS13 in a concentration-dependent manner with a half-maximal inhibitory concentration (IC50) of ~13 μM, ~70 μM, and ~17 μM, respectively. Unconjugated bilirubin also dose-dependently inhibits the cleavage of multimeric VWF by ADAMTS13 under denaturing conditions. The inhibitory activity of bilirubin on the cleavage of D633-rVWF73-H and multimeric VWF, but not F485-rVWF73-H, was eliminated after incubation with bilirubin oxidase that converts bilirubin to biliverdin. Furthermore, plasma ADAMTS13 activity in patients with hyperbilirubinemia is lower prior to than after treatment with bilirubin oxidase. Conclusions unconjugated bilirubin directly inhibits ADAMTS13’s ability to cleave both peptidyl and native VWF substrates in addition to its interference with certain fluorogenic assays. Our findings may help proper interpretation of ADAMTS13 results under pathological conditions. Whether elevated serum unconjugated bilirubin has an adverse effect in vivo remains to be determined in our future study. PMID:25782102

Changes in the pattern of distribution of von Willebrand factor in rat aortic endothelial cells following thrombin generation in vivo.

PubMed

Senis, Y A; Richardson, M; Tinlin, S; Maurice, D H; Giles, A R

1996-04-01

The pattern of distribution of von Willebrand factor (VWF) in relatively large sheets of rat aortic endothelial cells (EC) obtained by the Häutchen technique were analysed by immunocytochemistry and light microscopy. EC were examined pre and post administration of a procoagulant mixture of factor Xa (F.Xa) and phosphotidylcholine/phosphotidylserine (PCPS) vesicles which was demonstrated to result in the selective loss of high molecular weight multimers (HMWM) of plasma VWF in the rat. In placebo animals the pattern was heterogenous both in overall distribution and in individual cells which showed both a diffuse and granular pattern. Groups of intensely stained EC were oriented parallel to the longitudinal axis of the aorta and staining was particularly prominent around the orifices of the intercostal arteries, implicating shear-stress as a possible factor in VWF expression by EC. Changes in the pattern of distribution of staining were observed at various time points post-infusion of F.Xa/PCPS, suggesting the immediate release of VWF from EC stores followed by the recruitment of EC to synthesize and store VWF. These changes are consistent with the decrease in EC Weibel-Palade Body (WPB) content observed by EM in previously reported studies using this model.

Relationship between ABO blood groups and von Willebrand factor, ADAMTS13 and factor VIII in patients undergoing hemodialysis.

PubMed

Rios, Danyelle R A; Fernandes, Ana Paula; Figueiredo, Roberta C; Guimarães, Daniela A M; Ferreira, Cláudia N; Simões E Silva, Ana C; Carvalho, Maria G; Gomes, Karina B; Dusse, Luci Maria Sant' Ana

2012-05-01

Several studies have demonstrated that non-O blood groups subjects present an increased VTE risk as compared to those carrying O blood group. The aim of this study was to investigate the ABO blood groups influence on factor VIII (FVIII) activity, von Willebrand factor (VWF), and ADAMTS13 plasma levels in patients undergoing hemodialysis (HD). Patients undergoing HD (N=195) and 80 healthy subjects (control group) were eligible for this cross-sectional study. The ABO blood group phenotyping was performed by the reverse technique. FVIII activity was measured through coagulometric method, and VWF and ADAMTS13 antigens were assessed by ELISA. FVIII activity and VWF levels were significantly higher and ADAMTS13 levels was decreased in HD patients, as compared to healthy subjects (P < 0.001, in three cases). HD patients carrying non-O blood groups showed a significant increase in FVIII activity (P = 0.001) and VWF levels (P < 0.001) when compared to carriers of O blood group. However, no significant difference was observed in ADAMTS13 levels (P = 0.767). In the control group, increased in FVIII activity (P = 0.001) and VWF levels (P = 0.002) and decreased in ADAMTS13 levels (P = 0.005) were observed in subjects carrying non-O blood groups as compared to carriers of O blood group.Our data confirmed that ABO blood group is an important risk factor for increased procoagulant factors in plasma, as FVIII and VWF. Admitting the possible role of kidneys in ADAMTS13 synthesis or on its metabolism, HD patients were not able to increase ADAMTS13 levels in order to compensate the increase of VWF levels mediated by ABO blood groups. Considering that non-O blood groups constitute a risk factor for thrombosis, it is reasonable to admit that A, B and AB HD patients need a careful and continuous follow-up in order to minimize thrombotic events.

[Successful treatment with rituximab in a patient with primary thymic MALT lymphoma complicated with acquired von Willebrand syndrome and Sjögren syndrome].

PubMed

Iwabuchi, Tamiko; Kimura, Yukihiko; Suzuki, Takashi; Hayashi, Haeru; Fujimoto, Hiroaki; Hashimoto, Yuko; Ogawa, Takashi; Kusama, Hiroshi; Fukutake, Katsuyuki; Ohyashiki, Kazuma

2011-04-01

A 53-year-old female developed epigastric discomfort and back pain in 2007. Diagnostic imaging studies demonstrated a soft tissue tumor with heterogeneous enhancement in the anterior mediastinum and multiple nodules in the right lung. She underwent expanded thymectomy with subtotal resection of the right lung. The pathological diagnosis was primary thymic mucosa-associated lymphoid tissue (MALT) lymphoma. The patient complained of ocular discomfort, oral dryness and continuous nasal bleeding in 2007. Detailed examination led to a diagnosis of Sjögren syndrome and acquired von Willebrand syndrome. Rituximab treatment for residual disease achieved not only a reduction of the lung MALT lymphoma but also clinical and hematological remission of both syndromes. This is, to our knowledge, the first reported case of primary thymic MALT lymphoma accompanied by Sjögren and acquired von Willebrand syndromes.

Haemostasis prophylaxis using single dose desmopressin acetate and extended use epsilon aminocaproic acid for adenotonsillectomy in patients with type 1 von Willebrand disease.

PubMed

Santoro, C; Hsu, F; Dimichele, D M

2012-03-01

In patients with confirmed or suspected type 1 von Willebrand disease (VWD), adenotonsillectomy has been reported to be associated with a rate of peri-operative hemorrhage between 8 and 23%. Desmopressin acetate (DDAVP, 1-deamino 8-D arginine- vasopressin) is the treatment of choice for type 1 patients with baseline von Willebrand factor levels of 10 IU/dL or greater. DDAVP is generally well tolerated; however, severe hyponatremia and seizures have been reported in young children less than 2 years of age, limiting its use in this age group. Antifibrinolytic therapy plays an important adjunctive role in the effective treatment of mucocutaneous bleeding, particularly in the oropharynx where the salivary concentration of fibrinolytic enzymes is high. During the past 10 years, we treated 6 pediatric patients with mild/moderate type 1 VWD undergoing an adenotonsillar procedure at our institution with the same hemostatic regimen consisting of one single dose of DDAVP and an extended use of EACA. In this small case series, the above mentioned prophylactic treatment regimen was both well tolerated and efficacious in controlling hemorrhage. Furthermore, DDAVP-related complications were avoided in a pediatric population with a higher risk of developing them. © 2011 Blackwell Publishing Ltd.

pH-Dependent Interactions in Dimers Govern the Mechanics and Structure of von Willebrand Factor.

PubMed

Müller, Jochen P; Löf, Achim; Mielke, Salomé; Obser, Tobias; Bruetzel, Linda K; Vanderlinden, Willem; Lipfert, Jan; Schneppenheim, Reinhard; Benoit, Martin

2016-07-26

Von Willebrand factor (VWF) is a multimeric plasma glycoprotein that is activated for hemostasis by increased hydrodynamic forces at sites of vascular injury. Here, we present data from atomic force microscopy-based single-molecule force measurements, atomic force microscopy imaging, and small-angle x-ray scattering to show that the structure and mechanics of VWF are governed by multiple pH-dependent interactions with opposite trends within dimeric subunits. In particular, the recently discovered strong intermonomer interaction, which induces a firmly closed conformation of dimers and crucially involves the D4 domain, was observed with highest frequency at pH 7.4, but was essentially absent at pH values below 6.8. However, below pH 6.8, the ratio of compact dimers increased with decreasing pH, in line with a previous transmission electron microscopy study. These findings indicated that the compactness of dimers at pH values below 6.8 is promoted by other interactions that possess low mechanical resistance compared with the strong intermonomer interaction. By investigating deletion constructs, we found that compactness under acidic conditions is primarily mediated by the D4 domain, i.e., remarkably by the same domain that also mediates the strong intermonomer interaction. As our data suggest that VWF has the highest mechanical resistance at physiological pH, local deviations from physiological pH (e.g., at sites of vascular injury) may represent a means to enhance VWF's hemostatic activity where needed. Copyright © 2016 Biophysical Society. Published by Elsevier Inc. All rights reserved.

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

Space and Time Resolved Detection of Platelet Activation and von Willebrand Factor Conformational Changes in Deep Suspensions.

PubMed

Biasetti, Jacopo; Sampath, Kaushik; Cortez, Angel; Azhir, Alaleh; Gilad, Assaf A; Kickler, Thomas S; Obser, Tobias; Ruggeri, Zaverio M; Katz, Joseph

2017-01-01

Tracking cells and proteins' phenotypic changes in deep suspensions is critical for the direct imaging of blood-related phenomena in in vitro replica of cardiovascular systems and blood-handling devices. This paper introduces fluorescence imaging techniques for space and time resolved detection of platelet activation, von Willebrand factor (VWF) conformational changes, and VWF-platelet interaction in deep suspensions. Labeled VWF, platelets, and VWF-platelet strands are suspended in deep cuvettes, illuminated, and imaged with a high-sensitivity EM-CCD camera, allowing detection using an exposure time of 1 ms. In-house postprocessing algorithms identify and track the moving signals. Recombinant VWF-eGFP (rVWF-eGFP) and VWF labeled with an FITC-conjugated polyclonal antibody are employed. Anti-P-Selectin FITC-conjugated antibodies and the calcium-sensitive probe Indo-1 are used to detect activated platelets. A positive correlation between the mean number of platelets detected per image and the percentage of activated platelets determined through flow cytometry is obtained, validating the technique. An increase in the number of rVWF-eGFP signals upon exposure to shear stress demonstrates the technique's ability to detect breakup of self-aggregates. VWF globular and unfolded conformations and self-aggregation are also observed. The ability to track the size and shape of VWF-platelet strands in space and time provides means to detect pro- and antithrombotic processes.

[Atypical hemolytic and uremic syndrome associated with von Willebrand factor-cleaving protease (ADAMTS 13) deficiency in children].

PubMed

Ben Abdallah Chabchoub, R; Boukedi, A; Bensalah, M; Maalej, B; Gargour, L; Turk, F; Ben Halima, N; Wolf, M; Veyradier, A; Mahfoudh, A

2013-08-01

Hemolytic and uremic syndrome (HUS) is a classical form of thrombotic microangiopathies characterized by the association of hemolytic anemia with schizocytes, thrombocytopenia, and acute renal failure. Two forms of HUS have been described: the typical form that occurs after ingestion of a strain of bacteria, usually Escherichia coli types, which expresses verotoxin (also called shiga-like toxin), typically followed by bloody diarrhea, and atypical HUS, which is rare during childhood and can also be revealed by bloody diarrhea. We report a case of a 25-month-old infant who presented with hematuria and pallor after an episode of diarrhea. Biological tests revealed anemia, thrombocytopenia, and renal failure. The diagnosis of typical HUS was made, but the causal microorganism was not identified. Progression was favorable within 5 days of plasma transfusions. Two months later, the patient presented with the same symptoms and neurological impairment without any diarrhea. Von Willebrand factor-cleaving protease activity (ADAMTS 13) was low. Therefore, the diagnosis of atypical HUS by severe deficiency of ADAMTS 13 was suggested. The treatment was based on plasma transfusions resulting in remission. Atypical HUS associated with severe ADAMTS 13 deficiency rarely occurs in childhood. The prognosis, usually threatening, has been completely transformed thanks to a better understanding of the pathogenesis and to therapeutic progress. Copyright © 2013. Published by Elsevier SAS.

Performance related factors are the main determinants of the von Willebrand factor response to exhaustive physical exercise.

PubMed

van Loon, Janine E; Sonneveld, Michelle A H; Praet, Stephan F E; de Maat, Moniek P M; Leebeek, Frank W G

2014-01-01

Physical stress triggers the endothelium to release von Willebrand Factor (VWF) from the Weibel Palade bodies. Since VWF is a risk factor for arterial thrombosis, it is of great interest to discover determinants of VWF response to physical stress. We aimed to determine the main mediators of the VWF increase by exhaustive physical exercise. 105 healthy individuals (18-35 years) were included in this study. Each participant performed an incremental exhaustive exercise test on a cycle ergometer. Respiratory gas exchange measurements were obtained while cardiac function was continuously monitored. Blood was collected at baseline and directly after exhaustion. VWF antigen (VWF:Ag) levels, VWF collagen binding (VWF:CB) levels, ADAMTS13 activity and common variations in Syntaxin Binding Protein-5 (STXBP5, rs1039084 and rs9399599), Syntaxin-2 (STX2, rs7978987) and VWF (promoter, rs7965413) were determined. The median VWF:Ag level at baseline was 0.94 IU/mL [IQR 0.8-1.1] and increased with 47% [IQR 25-73] after exhaustive exercise to a median maximum VWF:Ag of 1.38 IU/mL [IQR 1.1-1.8] (p<0.0001). VWF:CB levels and ADAMTS13 activity both also increased after exhaustive exercise (median increase 43% and 12%, both p<0.0001). The strongest determinants of the VWF:Ag level increase are performance related (p<0.0001). We observed a gender difference in VWF:Ag response to exercise (females 1.2 IU/mL; males 1.7 IU/mL, p = 0.001), which was associated by a difference in performance. Genetic variations in STXBP5, STX2 and the VWF promoter were not associated with VWF:Ag levels at baseline nor with the VWF:Ag increase. VWF:Ag levels strongly increase upon exhaustive exercise and this increase is strongly determined by physical fitness level and the intensity of the exercise, while there is no clear effect of genetic variation in STXBP5, STX2 and the VWF promoter.

Differential sensitivity of von Willebrand factor (VWF) 'activity' assays to large and small VWF molecular weight forms: a cross-laboratory study comparing ristocetin cofactor, collagen-binding and mAb-based assays.

PubMed

Favaloro, E J; Bonar, R; Chapman, K; Meiring, M; Funk Adcock, D

2012-06-01

von Willebrand disease (VWD), the most common inherited bleeding disorder, is caused by deficiencies and/or defects in von Willebrand factor (VWF). An effective diagnostic and VWD typing strategy requires plasma testing for factor VIII, and VWF antigen plus one or more VWF 'activity' assays. VWF activity is classically assessed by using VWF ristocetin cofactor activity (VWF:RCo), although VWF collagen-binding (VWF:CB) and VWF mAb-based (VWF activity [VWF:Act]) assays are used by some laboratories. To perform a cross-laboratory study to specifically evaluate these three VWF activity assays for comparative sensitivity to loss of high molecular weight (HMW) VWF, representing the form of VWF that is most functionally active and that is absent in some types of VWD, namely 2A and 2B. A set of eight samples, including six selectively representing stepwise reduction in HMW VWF, were tested by 51 different laboratories using a variety of assays. The combined data showed that the VWF:CB and VWF:RCo assays had higher sensitivity to the loss of HMW VWF than did the VWF:Act assay. Moreover, within-method analysis identified better HMW VWF sensitivity of some VWF:CB assays than of others, with all VWF:CB assays still showing better sensitivity than the VWF:Act assay. Differences were also identified between VWF:RCo methodologies on the basis of either platelet aggregometry or as performed on automated analyzers. We believe that these results have significant clinical implications for the diagnosis of VWD and monitoring of its therapy, as well as for the future diagnosis and therapy monitoring of thrombotic thrombocytopenic purpura. © 2012 International Society on Thrombosis and Haemostasis.

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.

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. © 2016. Published by The Company of Biologists Ltd.

Relationship between the von Willebrand Factor Plasma Concentration and Ultrasonographic Doppler Findings in Pregnancies Complicated by Hypertensive Disorders: A Pilot Study.

PubMed

Szpera-Gozdziewicz, Agata; Gozdziewicz, Tomasz; Boruczkowski, Maciej; Dworacki, Grzegorz; Breborowicz, Grzegorz H

2018-01-01

Recent evidence suggests that impaired cytotrophoblast proliferation and migration are major factors responsible for the development of hypertension in pregnancy. Studies report that von Willebrand factor (vWf) is a specific endothelial damage plasma marker. The aim of this study was to evaluate the relationship between vWf maternal plasma concentration and maternal and fetal Doppler flow measurements in pregnancies complicated by hypertension. It may provide additional insight into the pathophysiology of pregnancy-related hypertension and show the potential method for disease prevention and therapy. We created 3 study groups: pregnant women with chronic hypertension (n = 10), gestational hypertension (n = 18), preeclampsia (n = 21), and control (22 healthy pregnant women). Every woman underwent ultrasound Doppler flow measurements performed simultaneously with venous blood collection. The vWf plasma concentrations were assessed using the commercially available enzyme-linked immunosorbent assay kit. The preeclampsia group had significantly higher vWf plasma concentrations in those patients with ultrasonographic features of placental insufficiency than in those without these characteristics (638 ± 208 vs. 377 ± 74 ng/mL; p < 0.017). Our results may confirm the arrangement and severity of endothelial damage in preeclamptic patients and may have identified those patients with a significantly higher risk of developing cardiovascular disease. © 2018 S. Karger AG, Basel.

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

Clinical application of a rapid method using agarose gel electrophoresis and Western blotting to evaluate von Willebrand factor protease activity.

PubMed

Kirzek, D M; Rick, M E

2001-03-01

A method for evaluating the activity of the von Willebrand factor (vWF) protease is described, and a clinical application is illustrated. The procedure utilizes gel electrophoresis, Western blotting, and luminographic detection methods to evaluate the distribution of vWF multimers before and after incubation of clinical samples under conditions that favor proteolysis by this enzyme. Physiologically, the high-molecular-weight multimers of vWF are cleaved by the vWF protease under conditions of high shear stress in parts of the arterial circulation; cleavage of vWF multimers is also observed after exposure of vWF to denaturing agents in vitro and thus can serve as a laboratory test for the activity of the protease. vWF protease activity is decreased or absent in patients with thrombotic thrombocytopenic purpura due to an inhibiting autoantibody, and this leads to high levels of noncleaved vWF and to life-threatening thrombosis, thrombocytopenia and anemia. The assay evaluates the activity of the protease by assessing the cleavage of vWF multimers after patient plasmas are incubated in vitro under denaturing conditions. With the use of these electrophoresis and Western blotting techniques, patient plasmas can be rapidly assessed for the activity of the vWF protease which may aid in the treatment strategy for these patients.

One-pot preparation of conducting composite containing abundant amino groups on electrode surface for electrochemical detection of von willebrand factor

NASA Astrophysics Data System (ADS)

Wang, Wen; Ma, Chao; Li, Yi; Liu, Baihui; Tan, Liang

2018-03-01

A one-pot protocol based on cyclic voltammetric scan was employed to prepare new conducting composite that was abundant in amino groups. The scanning electron microscope, atomic force microscope, X-ray photoelectron spectroscopy and infrared spectrum characterization demonstrate that poly(azure A), gold nanoparticles, chitosan and cysteine were immobilized simultaneously on glassy carbon electrode surface. Von Willebrand factor (vWF) antibody (Ab) was subsequently assembled by using glutaraldehyde to construct the Ab/composite-modified electrode. The capture of vWF could inhibit the charge transfer between the ferri-/ferrocyanide probe and the electrode and exert the negative effect on the electrochemical response of the dye polymer in the conducting composite due to the strong steric hindrance effect. The DPV peak current change before and after the immunoreaction was found to be proportional to the logarithm of the vWF concentration from 0.001 to 100 μg mL-1 with a detection limit of 0.4 ng mL-1. The proposed label-free electrochemical method was employed in the investigation on the release of vWF by oxidation-injured vascular endothelial cells. The experimental results exhibit that the vWF content in growth medium was increased when the oxidation injury of the cells was intensified in the presence of H2O2.

Thrombomodulin, von Willebrand factor and E-selectin as plasma markers of endothelial damage/dysfunction and activation in pregnancy induced hypertension.

PubMed

Nadar, Sunil K; Al Yemeni, Eman; Blann, Andrew D; Lip, Gregory Y H

2004-01-01

Endothelial disturbance (whether activation, dysfunction or damage) is a likely pathogenic mechanism in pre-eclampsia and pregnancy-induced hypertension (PIH). We set out to determine which of three plasma markers of endothelial disturbance, indicating endothelial activation (E-selectin) or damage/dysfunction (von Willebrand factor (vWf), soluble thrombomodulin), would provide the best discriminator of PIH compared to normotensive pregnancy. Cross-sectional study of 36 consecutive women with PIH (age 31+/-6 years) and 36 consecutive women with normotensive pregnancies (age 29+/-5 years) of similar parity. Plasma levels of vWf, E-selectin and thrombomodulin were measured using ELISA. As expected, women with PIH had significantly higher levels of plasma vWf (by 19%, p=0.003), E-selectin (by 40%, p<0.001) and thrombomodulin (by 61%, p=0.01) than normotensive women. However, on stepwise multiple regression analysis, only thrombomodulin was an independent significant predictor of the presence of PIH (p=0.023). We conclude that although vWf, E-selectin and thrombomodulin are all raised in PIH, only thrombomodulin was independently associated with PIH. This molecule could potentially be useful in monitoring and in providing clues in aetiology and pathophysiology, and may have implications for the clinical complications associated with PIH.

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.

An anti-von Willebrand factor aptamer reduces platelet adhesion among patients receiving aspirin and clopidogrel in an ex vivo shear-induced arterial thrombosis.

PubMed

Arzamendi, Dabit; Dandachli, Firas; Théorêt, Jean-François; Ducrocq, Gregory; Chan, Mark; Mourad, Walid; Gilbert, James C; Schaub, Robert G; Tanguay, Jean-François; Merhi, Yahye

2011-01-01

The von Willebrand factor (vWF) aptamer, ARC1779 that blocks the binding of vWF A1-domain to platelet glycoprotein 1b (GPIb) at high shear, may deliver a site-specific antithrombotic effect. We investigated the efficiency of ARC1779 on platelet function in patients with coronary artery disease (CAD) on double antiplatelet therapy. Blood from patients taking aspirin and clopidogrel and from normal volunteers was treated ex vivo with ARC1779 or abciximab, either prior to perfusion (pretherapy) or 10 minutes following the initiation of perfusion (posttherapy) on damaged arteries. Under pre- but not posttherapy, platelet adhesion was significantly reduced by ARC1779 at 83 and 250 nmol/L and by abciximab (100 nmol/L) versus placebo (4.8, 3.8, and 2.9 vs 7.3 platelets × 10(6)/cm(2), P < .05). In contrast to abciximab, ARC1779 did not significantly affect platelet aggregation, P-selectin expression, and platelet-leukocyte binding. These proof-of-concept data may constitute the framework for randomized clinical investigations of this novel antiplatelet therapy among patients with CAD.

Specific electrostatic interactions between charged amino acid residues regulate binding of von Willebrand factor to blood platelets.

PubMed

Interlandi, Gianluca; Yakovenko, Olga; Tu, An-Yue; Harris, Jeff; Le, Jennie; Chen, Junmei; López, José A; Thomas, Wendy E

2017-11-10

The plasma protein von Willebrand factor (VWF) is essential for hemostasis initiation at sites of vascular injury. The platelet-binding A1 domain of VWF is connected to the VWF N-terminally located D'D3 domain through a relatively unstructured amino acid sequence, called here the N-terminal linker. This region has previously been shown to inhibit the binding of VWF to the platelet surface receptor glycoprotein Ibα (GpIbα). However, the molecular mechanism underlying the inhibitory function of the N-terminal linker has not been elucidated. Here, we show that an aspartate at position 1261 is the most critical residue of the N-terminal linker for inhibiting binding of the VWF A1 domain to GpIbα on platelets in blood flow. Through a combination of molecular dynamics simulations, mutagenesis, and A1-GpIbα binding experiments, we identified a network of salt bridges between Asp 1261 and the rest of A1 that lock the N-terminal linker in place such that it reduces binding to GpIbα. Mutations aimed at disrupting any of these salt bridges activated binding unless the mutated residue also formed a salt bridge with GpIbα, in which case the mutations inhibited the binding. These results show that interactions between charged amino acid residues are important both to directly stabilize the A1-GpIbα complex and to indirectly destabilize the complex through the N-terminal linker. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

von Willebrand factor (VWF) propeptide binding to VWF D'D3 domain attenuates platelet activation and adhesion.

PubMed

Madabhushi, Sri R; Shang, Chengwei; Dayananda, Kannayakanahalli M; Rittenhouse-Olson, Kate; Murphy, Mary; Ryan, Thomas E; Montgomery, Robert R; Neelamegham, Sriram

2012-05-17

Noncovalent association between the von Willebrand factor (VWF) propeptide (VWFpp) and mature VWF aids N-terminal multimerization and protein compartmentalization in storage granules. This association is currently thought to dissipate after secretion into blood. In the present study, we examined this proposition by quantifying the affinity and kinetics of VWFpp binding to mature VWF using surface plasmon resonance and by developing novel anti-VWF D'D3 mAbs. Our results show that the only binding site for VWFpp in mature VWF is in its D'D3 domain. At pH 6.2 and 10mM Ca(2+), conditions mimicking intracellular compartments, VWFpp-VWF binding occurs with high affinity (K(D) = 0.2nM, k(off) = 8 × 10(-5) s(-1)). Significant, albeit weaker, binding (K(D) = 25nM, k(off) = 4 × 10(-3) s(-1)) occurs under physiologic conditions of pH 7.4 and 2.5mM Ca(2+). This interaction was also observed in human plasma (K(D) = 50nM). The addition of recombinant VWFpp in both flow-chamber-based platelet adhesion assays and viscometer-based shear-induced platelet aggregation and activation studies reduced platelet adhesion and activation partially. Anti-D'D3 mAb DD3.1, which blocks VWFpp binding to VWF-D'D3, also abrogated platelet adhesion, as shown by shear-induced platelet aggregation and activation studies. Our data demonstrate that VWFpp binding to mature VWF occurs in the circulation, which can regulate the hemostatic potential of VWF by reducing VWF binding to platelet GpIbα.

A short history of diagnostic tests for von Willebrand disease: in memory of Barry Firkin (1930 to 2001) and Ted Zimmerman (1937 to 1988).

PubMed

Koutts, Jerry

2006-07-01

By the end of the 1960s, von Willebrand disease (vWD) was accepted as a combined deficiency of factor (F) VIII coagulation and a plasma factor responsible for normal platelet adhesion. Just how these two functions related to each other was unclear, and the diagnostic tests available at the time were poorly reproducible, cumbersome, and unreliable. As a consequence, the condition was poorly delineated from other coagulation and platelet disorders. In the early 1970s, ristocetin-induced platelet aggregation was described and formed the basis of the first consistent and reliable test that quantified the platelet adhesive function missing in vWD. Immunoprecipitating techniques specific for the molecule missing in vWD were defined. The application of these technologies allowed a clearer understanding of the heterogeneity of vWD and continues to form a basis for the diagnosis of this condition. Concurrently, exploration of the structure and function of von Willebrand factor (vWF) has contributed greatly to the understanding of platelet physiology, ligand receptor interaction, and pathways of cellular interaction and activation. Despite all of the progress during the last 35 years, including extensive developments in the field of molecular biology and genetics of vWD, the diagnosis of this condition in many, if not most cases, remains controversial. The final plasma level of vWF is influenced substantially by epigenetic and environmental factors. This natural heterogeneity is further compounded by significant imprecision of existing tests. As a consequence, defining vWD on the basis of a variation from the normal range alone is more than likely to be incorrect. The high frequency of a positive bleeding disorder in the normal population does not assist discrimination. It has been suggested that the diagnosis of mild type 1 vWD be discarded because it does not exhibit consistent linkage to the VWF gene and does not predict bleeding.

ADAMTS-13 rapidly cleaves newly secreted ultralarge von Willebrand factor multimers on the endothelial surface under flowing conditions.

PubMed

Dong, Jing-fei; Moake, Joel L; Nolasco, Leticia; Bernardo, Aubrey; Arceneaux, Wendy; Shrimpton, Corie N; Schade, Alicia J; McIntire, Larry V; Fujikawa, Kazuo; López, José A

2002-12-01

Thrombotic thrombocytopenic purpura (TTP) is a devastating thrombotic disorder caused by widespread microvascular thrombi composed of platelets and von Willebrand factor (VWF). The disorder is associated with a deficiency of the VWF-cleaving metalloprotease, ADAMTS-13, with consequent accumulation of ultralarge (UL) VWF multimers in the plasma. ULVWF multimers, unlike plasma forms of VWF, attach spontaneously to platelet GP Ibalpha, a component of the GP Ib-IX-V complex. We have found that ULVWF multimers secreted from stimulated endothelial cells (ECs) remained anchored to the endothelial surface where platelets and Chinese hamster ovary cells expressing the GP Ib-IX-V complex attached to form long beads-on-a-string structures in the presence of fluid shear stresses in both the venous (2.5 dyne/cm(2)) and arterial (20 and 50 dyne/cm(2)) ranges. Although measurement of the activity of the ADAMTS-13 VWF-cleaving metalloprotease in vitro requires prolonged incubation of the enzyme with VWF under nonphysiologic conditions, EC-derived ULVWF strings with attached platelets were cleaved within seconds to minutes in the presence of normal plasma (containing approximately 100% ADAMTS-13 activity) or in the presence of partially purified ADAMTS-13. By contrast, the strings persisted for the entire period of perfusion (10 minutes) in the presence of plasma from patients with TTP containing 0% to 10% ADAMTS-13 activity. These results suggest that cleavage of EC-derived ULVWF multimers by ADAMTS-13 is a rapid physiologic process that occurs on endothelial cell surfaces.

Platelet-type von Willebrand Disease: Diagnostic Challenges. Flaws and Pitfalls Experienced in the THROMKID Quality Project.

PubMed

Maurer, M; Mesters, R; Schneppenheim, R; Knoefler, R; Streif, W

2015-05-01

Primary haemostasis defects comprise von Willebrand disease (VWD) and platelet disorders (PD). Although presenting with mild to moderate bleeding tendency in most cases, severe bleeding and blood loss may occur unexpectedly in trauma and surgery. Diagnosis of VWD and PD often remains difficult owing to the wide spectrum of clinical and laboratory manifestations. Platelet-type von Willebrand disease (PT-VWD) is frequently misdiagnosed as type 2B VWD. Discrimination between type 2B VWD and PT-VWD is crucial as treatment differs. A literature review revealed difficulties in diagnostic work-up and choice of optimal treatment of PT-VWD. Guidelines favour the therapeutic use of platelet concentrates. A telephone survey of diagnostic practice with regard to type 2B VWD/PT-VWD was conducted. The prevalence and incidence of type 2B and PT-VWD remained unclear, but PT-VWD may be underestimated. An international study estimated that PT-VWD constitutes up to 15% of the total number of patients diagnosed with type 2B VWD. Our survey confirmed difficulties with diagnosis and showed that some centres did not exclude PT-VWD in type 2B patients. Some authors emphasize that genetic testing is the gold standard for diagnosis, but functional testing allows immediate diagnosis. Due to the important therapeutic implications we suggest that type 2B VWD be confirmed by genetic testing and that in case of a negative result PT-VWD should be excluded. PT-VWD should be excluded in all suspected cases of type 2B. PT-VWD should be treated with platelet concentrates. © Georg Thieme Verlag KG Stuttgart · New York.

Characterization of an entomopathogenic fungi target integument protein, Bombyx mori single domain von Willebrand factor type C, in the silkworm, Bombyx mori.

PubMed

Han, F; Lu, A; Yuan, Y; Huang, W; Beerntsen, B T; Huang, J; Ling, E

2017-06-01

The insect cuticle works as the first line of defence to protect insects from pathogenic infections and water evaporation. However, the old cuticle must be shed in order to enter the next developmental stage. During each ecdysis, moulting fluids are produced and secreted into the area among the old and new cuticles. In a previous study, the protein Bombyx mori single domain von Willebrand factor type C (BmSVWC; BGIBMGA011399) was identified in the moulting fluids of Bo. mori and demonstrated to regulate ecdysis. In this study we show that in Bo. mori larvae, BmSVWC primarily locates to the integument (epidermal cells and cuticle), wing discs and head. During the moulting stage, BmSVWC is released into the moulting fluids, and is then produced again by epidermal cells after ecdysis. Fungal infection was shown to decrease the amount of BmSVWC in the cuticle, which indicates that BmSVWC is a target protein of entomopathogenic fungi. Thus, BmSVWC is mainly involved in maintaining the integrity of the integument structure, which serves to protect insects from physical damage and pathogenic infection. © 2017 The Royal Entomological Society.

Role of von Willebrand Factor and ADAMTS13 in early brain injury after experimental subarachnoid hemorrhage.

PubMed

Wan, H; Wang, Y; Ai, J; Brathwaite, S; Ni, H; Macdonald, R L; Hol, E M; Meijers, J C M; Vergouwen, M D I

2018-05-05

Early brain injury is an important determinant of poor functional outcome and case-fatality after aneurysmal subarachnoid hemorrhage (SAH) and associated with early platelet aggregation. No treatment exists for early brain injury after SAH. We investigated if von Willebrand Factor (VWF) is involved in the pathogenesis of early brain injury, and if ultra-early treatment with recombinant ADAMTS13 (rADAMTS13) reduces early brain injury after experimental SAH. Experimental SAH in mice was induced by prechiasmatic injection of non-anticoagulated blood from a littermate. The following experimental SAH groups were investigated: C57BL/6J control (n=21), VWF -/- (n=25), ADAMTS13 -/- (n=23), and C57BL/6J treated with rADAMTS13 (n=26). Mice were sacrificed at 2 hours post-SAH. Primary outcome measures were microglial activation (Iba-1 surface area) and neuronal injury (number of cleaved caspase-3 positive neurons). Compared with controls, microglial activation was decreased in VWF -/- mice (mean difference -20.0%; 95% CI: -4.0% to -38.6%), increased in ADAMTS13 -/- mice (mean difference +34.0%; 95% CI: 16.2% to 51.7%), and decreased in rADAMTS13 treated mice (mean difference -22.1%; 95% CI: -3.4% to -39.1%). Compared with controls (185 neurons [IQR 133-353]), neuronal injury in the cerebral cortex was decreased in VWF -/- mice (63 neurons [IQR 25-78]), not changed in ADAMTS13 -/- mice (53 neurons [IQR 26-221]), and reduced in rADAMTS13 treated mice (45 neurons [IQR 9-115]). Our findings suggest that VWF is involved in the pathogenesis of early brain injury and support the further study of rADAMTS13 as a treatment option for early brain injury after SAH. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Role of CD40 and ADAMTS13 in von Willebrand factor-mediated endothelial cell-platelet-monocyte interaction.

PubMed

Popa, Miruna; Tahir, Sibgha; Elrod, Julia; Kim, Su Hwan; Leuschner, Florian; Kessler, Thorsten; Bugert, Peter; Pohl, Ulrich; Wagner, Andreas H; Hecker, Markus

2018-06-12

Monocyte extravasation into the vessel wall is a key step in atherogenesis. It is still elusive how monocytes transmigrate through the endothelial cell (EC) monolayer at atherosclerosis predilection sites. Platelets tethered to ultra-large von Willebrand factor (ULVWF) multimers deposited on the luminal EC surface following CD40 ligand (CD154) stimulation may facilitate monocyte diapedesis. Human ECs grown in a parallel plate flow chamber for live-cell imaging or Transwell permeable supports for transmigration assay were exposed to fluid or orbital shear stress and CD154. Human isolated platelets and/or monocytes were superfused over or added on top of the EC monolayer. Plasma levels and activity of the ULVWF multimer-cleaving protease ADAMTS13 were compared between coronary artery disease (CAD) patients and controls and were verified by the bioassay. Two-photon intravital microscopy was performed to monitor CD154-dependent leukocyte recruitment in the cremaster microcirculation of ADAMTS13-deficient versus wild-type mice. CD154-induced ULVWF multimer-platelet string formation on the EC surface trapped monocytes and facilitated transmigration through the EC monolayer despite high shear stress. Two-photon intravital microscopy revealed CD154-induced ULVWF multimer-platelet string formation preferentially in venules, due to strong EC expression of CD40, causing prominent downstream leukocyte extravasation. Plasma ADAMTS13 abundance and activity were significantly reduced in CAD patients and strongly facilitated both ULVWF multimer-platelet string formation and monocyte trapping in vitro. Moderate ADAMTS13 deficiency in CAD patients augments CD154-mediated deposition of platelet-decorated ULVWF multimers on the luminal EC surface, reinforcing the trapping of circulating monocytes at atherosclerosis predilection sites and promoting their diapedesis.

Genetic drivers of von Willebrand Factor levels in an ischemic stroke population and association with risk for recurrent stroke

PubMed Central

Williams, Stephen R; Hsu, Fang-Chi; Keene, Keith L; Chen, Wei-Min; Dzhivhuho, Godfrey; Rowles, Joe L; Southerland, Andrew M; Furie, Karen L; Rich, Stephen S; Worrall, Bradford B; Sale, Michèle M

2017-01-01

Background and Purpose von Willebrand Factor (vWF) plays an important role in thrombus formation during cerebrovascular damage. We sought to investigate the potential role of circulating vWF in recurrent cerebrovascular events and identify genetic contributors to variation in vWF level in an ischemic stroke population. Methods We analyzed the effect of circulating vWF on risk of recurrent stroke using survival models in the Vitamin Intervention for Stroke Prevention (VISP) trial as well as the utility of vWF in reclassification over traditional factors. We conducted a genome-wide association study (GWAS) with imputation, based upon 1000 Genomes Project data, for circulating vWF levels and then interrogated loci previously associated with vWF levels. We performed expression quantitative trait locus (eQTL) analysis for vWF across different tissues. Results Elevated vWF levels were associated with increased risk for recurrent stroke in VISP. Adding vWF to traditional clinical parameters also improved recurrent stroke risk prediction. We identified SNPs significantly associated with circulating vWF at the ABO locus (p < 5×10-8) and replicated findings from previous genetic associations of vWF levels in humans. eQTL analyses demonstrate that most associated ABO SNPs were also associated with vWF gene expression. Conclusions Elevated vWF levels are associated with recurrent stroke in VISP. In the VISP population, genetic determinants of vWF levels that impact vWF gene expression were identified. These data add to our knowledge of the pathophysiologic and genetic basis for recurrent stroke risk, and may have implications for clinical care decision-making. PMID:28495826

Monitoring of coagulation factor therapy in patients with von Willebrand disease type 3 using a microchip flow chamber system.

PubMed

Ågren, Anna; Holmström, Margareta; Schmidt, David E; Hosokawa, Kazuya; Blombäck, Margareta; Hjemdahl, Paul

2017-01-05

Patients with type 3 von Willebrand disease (VWD-3) have no measurable levels of VW factor (VWF) and usually require treatment with VWF-FVIII concentrate to prevent and/or stop bleeding. Even though the patients are treated prophylactically, they may experience bleeding symptoms. The aim of this study was to evaluate the effect of VWF-FVIII concentrate treatment in VWD-3 patients with the Total Thrombus Analysis System (T-TAS ® ), which measures thrombus formation under flow conditions. Coagulation profiles of 10 VWD-3 patients were analysed using T-TAS before and 30 minutes after VWF-FVIII concentrate (Haemate ® ) injection. Results were compared to VWF- and FVIII activity in plasma, and results with thromboelastometry and ristocetin-activated platelet impedance aggregometry (Multiplate ® ) in whole blood. For comparison, 10 healthy controls were also analysed with T-TAS. A median dose of 27 (range 15-35) IU/kg of VWF-FVIII concentrate increased VWF- and FVIII activity as expected. T-TAS thrombus formation was enhanced when a tissue factor/collagen-coated flow chamber was used at low shear, but treatment effects at high shear using a collagen-coated flow chamber were minimal. Whole blood coagulation assessed by thromboelastometry was normal and did not change (p > 0.05) but ristocetin-induced platelet aggregation improved (p < 0.001). In conclusion, T-TAS detects effects of VWF-FVIII concentrate treatment on coagulation-dependent thrombus formation at low shear, but minor effects are observed on platelet-dependent thrombus formation at high shear. The poor prediction of bleeding by conventional laboratory monitoring in VWD-3 patients might be related to insufficient restoration of platelet-dependent thrombus formation.

D-dimer, factor VIII and von Willebrand factor predict a non-dipping pattern of blood pressure in hypertensive patients.

PubMed

Agorasti, Athanasia; Trivellas, Theodoros; Mourvati, Efthimia; Papadopoulos, Vasilios; Tsatalas, Konstantinos; Vargemezis, Vasilios; Passadakis, Ploumis

2013-06-01

The aim of this study is to assess whether the haemostatic markers D-dimer, factor VIII (FVIII) and von Willebrand factor (VWF) are predictive of non-dipping status in treated hypertensive patients; so, as easy available laboratory data can predict non-dipping pattern and help with the selection of the patients whom circadian blood pressure should be re-examined. Forty treated hypertensive patients with essential hypertension were included in the study. Twenty-four-hour ambulatory blood pressure monitoring was performed in all patients. Daytime and nocturnal average systolic, diastolic and mean blood pressures were calculated. Patients were characterised as "non-dippers" on the basis of a less than 10 % decline in nocturnal blood pressure (BP); either systolic or diastolic or mean (MAP). D-dimer as marker of fibrinolytic function, FVIII activity and VWF antigen as marker of endothelial dysfunction were measured on plasma. The predictive efficiency was analysed by receiver operating characteristic (ROC) curves. Youden index was used for the estimation of the cut-off points and the associated values for sensitivity and 1-specificity. Plasma levels of D-dimer, FVIII and VWF were significantly higher in non-dippers as compared with dippers, irrespective of the classification used (BP index); all P < 0.05. The ROC curves indicated a good diagnostic efficiency for D-dimer (AUC(ROC) = 0.697, 0.715 and 0.774), FVIII (AUC(ROC) = 0.714, 0.692 and 0.755) and VWF (AUC(ROC) = 0.706, 0.740 and 0.708) in distinguishing non-dipping pattern (systolic, diastolic or mean) in the study population; all P < 0.05. Among the three haemostatic markers, D-dimer presents the most satisfactory sensitivity/1-specificity for the differentiation of non-dippers, with a cut-off point >168 ng/ml (sensitivity/1-specificity for systolic BP non-dippers of 0.789/0.381, for diastolic BP non-dippers 0.923/0.444 and for MAP non-dippers 0.875/0.375). In conclusion, D-dimer has a good predictive value for

Evaluation of an heterogeneous group of patients with von Willebrand disease using an assay alternative to ristocetin induced platelet agglutination.

PubMed

Stufano, F; Baronciani, L; Pagliari, M T; Franchi, F; Cozzi, G; Garcia-Oya, I; Bucciarelli, P; Boscarino, M; Peyvandi, F

2015-10-01

Diagnosis of von Willebrand disease (VWD) type 2 usually relies on the discrepancy between the von Willebrand factor (VWF) ristocetin cofactor activity (VWF:RCo) and VWF antigen (VWF:Ag). Type 2B patients can be discriminated from other qualitative VWD variants by using ristocetin-induced platelet agglutination (RIPA) test. The major limitation of RIPA is the requirement of fresh blood sample. In this study, we evaluated the VWF gain-of-function mutant GPIb binding (VWF:GPIbM) and VWF:RCo assays to investigate whether the VWF:GPIbM/VWF:RCo ratio was able to identify the type 2B variant among an heterogeneous VWD population, previously characterized following the ISTH-SSC guidelines. Seventy-six VWD patients and 31 healthy subjects were evaluated by using VWF:Ag, VWF:RCo, and VWF:GPIbM assays. The mean (minimum-maximum values) VWF:GPIbM/VWF:RCo ratio was higher in type 2B patients (2.53, 0.84-6.11) than in healthy controls (1.05, 0.87-1.34), type 1 (0.85, 0.51-1.15), 2A (1.20, 0.36-2.82), and 2M (1.07, 0.91-1.38) (P < 0.0001). Type 2B variants were divided into four groups (A, B, C, and D) according to their different multimeric patterns. The mean value of the VWF:GPIbM/VWF:RCo ratio in the four groups showed an increasing trend from group A (1.08) to D (3.69), proportional to the loss of high molecular weight multimers. Among 32 type 2B patients, previously diagnosed with RIPA, 8 (mainly with a type I New York/Malmö phenotype) were not confirmed using the VWF:GPIbM/VWF:RCo ratio. Whenever the RIPA test is not feasible, the VWF:GPIbM/VWF:RCo ratio might help to identify severe type 2B VWD patients. © 2015 International Society on Thrombosis and Haemostasis.

In Situ Detection of Anaplasma spp. by DNA Target-Primed Rolling-Circle Amplification of a Padlock Probe and Intracellular Colocalization with Immunofluorescently Labeled Host Cell von Willebrand Factor ▿

PubMed Central

Wamsley, Heather L.; Barbet, Anthony F.

2008-01-01

Endothelial cell culture and preliminary immunofluorescent staining of Anaplasma-infected tissues suggest that endothelial cells may be an in vivo nidus of mammalian infection. To investigate endothelial cells and other potentially cryptic sites of Anaplasma sp. infection in mammalian tissues, a sensitive and specific isothermal in situ technique to detect localized Anaplasma gene sequences by using rolling-circle amplification of circularizable, linear, oligonucleotide probes (padlock probes) was developed. Cytospin preparations of uninfected or Anaplasma-infected cell cultures were examined using this technique. Via fluorescence microscopy, the technique described here, and a combination of differential interference contrast microscopy and von Willebrand factor immunofluorescence, Anaplasma phagocytophilum and Anaplasma marginale were successfully localized in situ within intact cultured mammalian cells. This work represents the first application of this in situ method for the detection of a microorganism and forms the foundation for future applications of this technique to detect, localize, and analyze Anaplasma nucleotide sequences in the tissues of infected mammalian and arthropod hosts and in cell cultures. PMID:18495855

von Willebrand factor and its cleaving protease ADAMTS13 balance in coronary artery vessels: Lessons learned from thrombotic thrombocytopenic purpura. A narrative review.

PubMed

Morici, Nuccia; Cantoni, Silvia; Panzeri, Francesco; Sacco, Alice; Rusconi, Chiara; Stucchi, Miriam; Oliva, Fabrizio; Cattaneo, Marco

2017-07-01

Deficiency of the von Willebrand factor-cleaving protease ADAMTS13 is central to the pathophysiology of thrombotic thrombocytopenic purpura (TTP), a microangiopathic syndrome that presents as an acute medical emergency. In this review we will explore the evidence of a two-way relationship between TTP and ACS. Moreover, we will review the evidence emerged from epidemiological studies of an inverse relationship between the plasma levels of ADAMTS13 and the risk of ACS. Pubmed, MEDLINE and EMBASE, CINHAL, COCHRANE and Google Scholar databases were searched from inception to January 2017. The search yielded 43 studies representing 23 unique patient cases, 5 case series, 5 cohort studies and 10 case-control studies. Most ACS cases developing in the setting of TTP resolved with standard treatment of the underlying microangiopathy, with only a few requiring coronary invasive management. Antiplatelet therapy was not usually prescribed and all of the currently used P2Y 12 were felt to be a potential trigger for a TTP-like syndrome, although our review revealed that the occurrence of TTP in patients treated with new P2Y 12 antagonists is rare. Most studies confirmed the inverse association among ADAMTS13 levels and ACS. The heart is a definite target organ in TTP. The clinical spectrum of its involvement is probably influenced by local factors that add on to the systemic deficiency characteristic of TTP. It follows that patients with TTP should be carefully monitored for ACS events, especially when multiple risk factors for coronary disease exist. Copyright © 2017 Elsevier Ltd. All rights reserved.

Resistance to Arteriosclerosis in Pigs with von Willebrand's Disease

PubMed Central

Fuster, Valentin; Bowie, E. J. Walter; Lewis, Jon C.; Fass, David N.; Owen, Charles A.; Brown, Arnold L.

1978-01-01

The aortas of 11 pigs (aged 1-3 yr) with homozygous von Willebrand's disease (vWd) were compared with those of 11 normal pigs of the same ages. Six of the controls exhibited multiple arteriosclerotic plaques with intimal thickening of 63-130 μm. In contrast, none of the pigs with vWd had multiple plaques, and only one had a lesion >2 mm in diameter. In a subsequent study, 3-mo-old pigs (11 controls and 7 with homozygous vWd) were placed on a 2% cholesterol diet for up to 6 mo. All of the controls developed arteriosclerotic plaques in the aorta, and in nine of the controls, at least 13% of the entire surface was involved. Intimal thickness ranged up to 390 μm. In contrast, four of the pigs with vWd did not develop such lesions, two developed arteriosclerotic lesions affecting 6 and 7% of the aortic surface, and the seventh had 13% of the aortic surface involved. Most of the pigs with vWd, however, developed flat fatty lesions in contrast to the normal pigs whether on the normal or the high cholesterol diet. There was blue staining of the flat fatty lesions when two pigs with vWd were injected with Evans blue dye antemortem. By electron microscopy, severe endothelial damage was apparent, but there was no intimal proliferation. The coincidence of the impaired platelet-arterial wall interaction and lack of arteriosclerosis in this bleeding disease is discussed. Images PMID:305924

von Willebrand factor as a novel noninvasive predictor of portal hypertension and esophageal varices in hepatitis B patients with cirrhosis.

PubMed

Wu, Hao; Yan, Shiping; Wang, Guangchuan; Cui, Shaobo; Zhang, Chunqing; Zhu, Qiang

2015-01-01

At present, there is no perfect noninvasive method to assess portal hypertension and esophageal varices. Early predicting esophageal varices can provide evidence for managing cirrhotic patients. We aimed to further investigate von Willebrand factor (vWF) as a noninvasive predictor of portal hypertension, especially of esophageal varices. A total of 60 hepatitis B patients with cirrhosis and 45 healthy subjects were enrolled in this study. Levels of six markers were examined. All patients underwent hepatic venous pressure gradient (HVPG) and esophagogastroduodenoscopy. We evaluated the performance of six factors for diagnosis of portal hypertension and esophageal varices. The vWF levels in liver tissues were observed by immunohistochemistry. Correlations between the level of vWF in liver tissues and HVPG and between levels of vWF in tissues and plasma were examined. Cutoff values of plasma vWF (1510.5 mU/mL and 1701 mU/mL) showed high positive predictive value (PPV, 90.2% and 87.5%) in predicting clinically significant portal hypertension and severe portal hypertension. Cutoff values of vWF (1414 mU/ml and 1990 mU/mL, PPV 90.3% and 86.3%, respectively) were provided to detect the presence and degree of esophageal varices. Linear correlations were observed between levels of vWF in liver tissues and HVPG (r(2) = 0.552, p < 0.001) and between the level of vWF in liver tissues and in plasma (r(2) = 0.461, p < 0.001). The vWF is a noninvasive predictor of portal hypertension and esophageal varices in hepatitis B patients with cirrhosis. Increased levels of vWF in liver tissues may induce the elevated plasma vWF levels, but molecular mechanism is needed for further study.

Differential roles of fibrinogen and von Willebrand factor on clot formation and platelet adhesion in reconstituted and immune thrombocytopenia.

PubMed

Misgav, Mudi; Shenkman, Boris; Budnik, Ivan; Einav, Yulia; Martinowitz, Uri

2011-05-01

Bleeding tendencies in immune thrombocytopenia (ITP) do not always correlate with the number of platelets, suggesting platelet function variation. We used a model of normal whole blood thrombocytopenia to compare platelet function and other hemostatic variables with ITP patients. We further investigated the effect of in vitro spiking with von Willebrand factor (vWF) and fibrinogen on platelet function and hemostatic variables. The Cone and Plate(let) Analyzer was used to measure platelet adhesion (surface coverage [SC], %) and aggregation (average size, μm(2)) under defined shear rate (1200 s(-1)). Rotational thromboelastometry was used to determine variables of clot formation triggered by CaCl(2) and tissue factor. In both the model of thrombocytopenia as well as in ITP, the SC and to some extent the average size were correlated to the platelet number over a range of 5 to 80 × 10(6)/mL. The results obtained for most ITP samples were within the boundaries of the lower and upper limits set by the whole blood model of thrombocytopenia. The addition of 2 U/mL vWF (Haemate-P) to whole blood (calculated to plasma volume) results in an increase in the SC and average size without affecting clot formation. Spiking with fibrinogen (100 and 300 mg/dL) did not affect platelet deposition but improved clot formation. Using a model of whole blood thrombocytopenia enables us to establish reference variables for the Cone and Plate(let) Analyzer and rotational thromboelastometry and to assess platelet function and clot formation in the presence of severe thrombocytopenia. We demonstrated that in most cases of ITP, platelet function is comparable to normal platelets. This work also suggests that vWF and fibrinogen differentially affect primary and secondary hemostasis and therefore both may perform a function in the bleeding phenotype and possibly may be considered for treatment in patients with ITP. © 2011 International Anesthesia Research Society

Dogs with heart diseases causing turbulent high-velocity blood flow have changes in platelet function and von Willebrand factor multimer distribution.

PubMed

Tarnow, Inge; Kristensen, Annemarie T; Olsen, Lisbeth H; Falk, Torkel; Haubro, Lotte; Pedersen, Lotte G; Pedersen, Henrik D

2005-01-01

The purpose of this prospective study was to investigate platelet function using in vitro tests based on both high and low shear rates and von Willebrand factor (vWf) multimeric composition in dogs with cardiac disease and turbulent high-velocity blood flow. Client-owned asymptomatic, untreated dogs were divided into 4 groups: 14 Cavalier King Charles Spaniels (Cavaliers) with mitral valve prolapse (MVP) and no or minimal mitral regurgitation (MR), 17 Cavaliers with MVP and moderate to severe MR, 14 control dogs, and 10 dogs with subaortic stenosis (SAS). Clinical examinations and echocardiography were performed in all dogs. PFA100 closure times (the ability of platelets to occlude a hole in a membrane at high shear rates), platelet activation markers (plasma thromboxane B2 concentration, platelet surface P-selectin expression), platelet aggregation (in whole blood and platelet-rich plasma with 3 different agonists), and vWf multimers were analyzed. Cavaliers with moderate to severe MR and dogs with SAS had longer closure times and a lower percentage of the largest vWf multimers than did controls. Maximal aggregation responses were unchanged in dogs with SAS but enhanced in Cavaliers with MVP (regardless of MR status) compared with control dogs. No significant difference in platelet activation markers was found among groups. The data suggest that a form of platelet dysfunction detected at high shear rates was present in dogs with MR and SAS, possibly associated with a qualitative vWf defect. Aggregation results suggest increased platelet reactivity in Cavaliers, but the platelets did not appear to circulate in a preactivated state in either disease.

Protein Replacement Therapy and Gene Transfer in Canine Models of Hemophilia A, Hemophilia B, von Willebrand Disease, and Factor VII Deficiency

PubMed Central

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.

2011-01-01

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. PMID:19293459

Functional characterisation of the type 1 von Willebrand disease candidate VWF gene variants: p.M771I, p.L881R and p.P1413L

PubMed Central

Berber, Ergul; Ozbil, Mehmet; Brown, Christine; Baslar, Zafer; Caglayan, S. Hande; Lillicrap, David

2017-01-01

Background Abnormalities in the biosynthetic pathway or increased clearance of plasma von Willebrand factor (VWF) are likely to contribute to decreased plasma VWF levels in inherited type 1 von Willebrand disease (VWD). Recent studies demonstrated that 65% of type 1 VWD patients have candidate VWF mutations, the majority of which are missense variants. The purpose of this study was to explore the effects of three VWF missense mutations (p.M771I, p.L881R and p.P1413L) located in different functional domains of VWF, reported as candidate mutations in type 1 VWD patients in the course of the MCMDM-1VWD study. Materials and methods The focus of these studies was on the intracellular biosynthetic processing and localisation of VWF in a heterologous cell system. Molecular dynamic simulation for p.M771I and p.P1413L was also performed to analyse the conformational effects of the changes. Results As determined by immunofluorescence antibody staining and confocal microscopy of HEK293 cells, the intracellular localisation of recombinant VWF with the p.M771I variation was impaired. Transient transfection studies and phorbol myristate acetate stimulation in COS-7 cells revealed significant intracellular retention. In addition, major loss of VWF multimers was observed for only the p.M771I mutation. Molecular dynamic simulations on p.M771I mutant VWF revealed distinct structural rearrangements including a large deviation in the E’ domain, and significant loss of β-sheet secondary structure. Discussion The pathogenic effects of candidate VWF gene mutations were explored in this study. In vitro expression studies in heterologous cell systems revealed impaired secretion of VWF and a dominant negative effect on the processing of the wild-type protein for only the p.M771I mutation and none of the mutations affected the regulated secretion. PMID:27483487

Functional characterisation of the type 1 von Willebrand disease candidate VWF gene variants: p.M771I, p.L881R and p.P1413L.

PubMed

Berber, Ergul; Ozbil, Mehmet; Brown, Christine; Baslar, Zafer; Caglayan, S Hande; Lillicrap, David

2017-10-01

Abnormalities in the biosynthetic pathway or increased clearance of plasma von Willebrand factor (VWF) are likely to contribute to decreased plasma VWF levels in inherited type 1 von Willebrand disease (VWD). Recent studies demonstrated that 65% of type 1 VWD patients have candidate VWF mutations, the majority of which are missense variants. The purpose of this study was to explore the effects of three VWF missense mutations (p.M771I, p.L881R and p.P1413L) located in different functional domains of VWF, reported as candidate mutations in type 1 VWD patients in the course of the MCMDM-1VWD study. The focus of these studies was on the intracellular biosynthetic processing and localisation of VWF in a heterologous cell system. Molecular dynamic simulation for p.M771I and p.P1413L was also performed to analyse the conformational effects of the changes. As determined by immunofluorescence antibody staining and confocal microscopy of HEK293 cells, the intracellular localisation of recombinant VWF with the p.M771I variation was impaired. Transient transfection studies and phorbol myristate acetate stimulation in COS-7 cells revealed significant intracellular retention. In addition, major loss of VWF multimers was observed for only the p.M771I mutation. Molecular dynamic simulations on p.M771I mutant VWF revealed distinct structural rearrangements including a large deviation in the E' domain, and significant loss of β-sheet secondary structure. The pathogenic effects of candidate VWF gene mutations were explored in this study. In vitro expression studies in heterologous cell systems revealed impaired secretion of VWF and a dominant negative effect on the processing of the wild-type protein for only the p.M771I mutation and none of the mutations affected the regulated secretion.

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.

Structural analyses of von Willebrand factor C domains of collagen 2A and CCN3 reveal an alternative mode of binding to bone morphogenetic protein-2.

PubMed

Xu, Emma-Ruoqi; Blythe, Emily E; Fischer, Gerhard; Hyvönen, Marko

2017-07-28

Bone morphogenetic proteins (BMPs) are secreted growth factors that promote differentiation processes in embryogenesis and tissue development. Regulation of BMP signaling involves binding to a variety of extracellular proteins, among which are many von Willebrand factor C (vWC) domain-containing proteins. Although the crystal structure of the complex of crossveinless-2 (CV-2) vWC1 and BMP-2 previously revealed one mode of the vWC/BMP-binding mechanism, other vWC domains may bind to BMP differently. Here, using X-ray crystallography, we present for the first time structures of the vWC domains of two proteins thought to interact with BMP-2: collagen IIA and matricellular protein CCN3. We found that these two vWC domains share a similar N-terminal fold that differs greatly from that in CV-2 vWC, which comprises its BMP-2-binding site. We analyzed the ability of these vWC domains to directly bind to BMP-2 and detected an interaction only between the collagen IIa vWC and BMP-2. Guided by the collagen IIa vWC domain crystal structure and conservation of surface residues among orthologous domains, we mapped the BMP-binding epitope on the subdomain 1 of the vWC domain. This binding site is different from that previously observed in the complex between CV-2 vWC and BMP-2, revealing an alternative mode of interaction between vWC domains and BMPs. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

The Carmat Bioprosthetic Total Artificial Heart Is Associated With Early Hemostatic Recovery and no Acquired von Willebrand Syndrome in Calves.

PubMed

Smadja, David M; Susen, Sophie; Rauch, Antoine; Cholley, Bernard; Latrémouille, Christian; Duveau, Daniel; Zilberstein, Luca; Méléard, Denis; Boughenou, Marie-Fazia; Belle, Eric Van; Gaussem, Pascale; Capel, Antoine; Jansen, Piet; Carpentier, Alain

2017-10-01

To determine hemostasis perturbations, including von Willebrand factor (VWF) multimers, after implantation of a new bioprosthetic and pulsatile total artificial heart (TAH). Preclinical study SETTING: Single-center biosurgical research laboratory. Female Charolais calves, 2-to-6 months old, weighing 102-to-122 kg. Surgical implantation of TAH through a mid-sternotomy approach. Four of 12 calves had a support duration of several days (4, 4, 8, and 10 days), allowing for the exploration of early steps of hemostasis parameters, including prothrombin time; coagulation factor levels (II, V, VII+X, and fibrinogen); and platelet count. Multimeric analysis of VWF was performed to detect a potential loss of high-molecular weight (HMW) multimers, as previously described for continuous flow rotary blood pumps. Despite the absence of anticoagulant treatment administered in the postoperative phase, no signs of coagulation activation were detected. Indeed, after an immediate postsurgery decrease of prothrombin time, platelet count, and coagulation factor levels, most parameters returned to baseline values. HMW multimers of VWF remained stable either after initiation or during days of support. Coagulation parameters and platelet count recovery in the postoperative phase of the Carmat TAH (Camat SA, Velizy Villacoublay Cedex, France) implantation in calves, in the absence of anticoagulant treatment and associated with the absence of decrease in HMW multimers of VWF, is in line with early hemocompatibility that is currently being validated in human clinical studies. Copyright © 2017 Elsevier Inc. All rights reserved.

Acquired von Willebrand Syndrome Associated to Secondary IgM MGUS Emerging after Autologous Stem Cell Transplantation for AL Amyloidosis

PubMed Central

Qamar, Hina; Lee, Adrienne; Valentine, Karen; Skeith, Leslie; Jimenez-Zepeda, Victor H

2017-01-01

Acquired von Willebrand syndrome (AVWS) is a rare hemorrhagic disorder that occurs in patients with no prior personal or family history of bleeding. Here, we describe a case of AVWS occurring after autologous stem cell transplantation (ASCT). Interestingly, AVWS developed after bortezomib-based induction and conditioning regimens. Recent evidence suggests that the proximity of the bortezomib therapy to the collection of stem cells with consequent depletion of regulatory T cells after the conditioning regimen could explain some of the unusual autoimmune complications reported in patients receiving bortezomib prior to ASCT. In addition, this patient developed a secondary MGUS post-ASCT, which may have also contributed to the AVWS. To the best of our knowledge, this is the first case of post-ASCT AVWS reported. Prospective data is needed to better elucidate the mechanisms by which these unusual complications occur in patients receiving bortezomib prior to ASCT. PMID:28512563

Acquired von Willebrand Syndrome Associated to Secondary IgM MGUS Emerging after Autologous Stem Cell Transplantation for AL Amyloidosis.

PubMed

Qamar, Hina; Lee, Adrienne; Valentine, Karen; Skeith, Leslie; Jimenez-Zepeda, Victor H

2017-01-01

Acquired von Willebrand syndrome (AVWS) is a rare hemorrhagic disorder that occurs in patients with no prior personal or family history of bleeding. Here, we describe a case of AVWS occurring after autologous stem cell transplantation (ASCT). Interestingly, AVWS developed after bortezomib-based induction and conditioning regimens. Recent evidence suggests that the proximity of the bortezomib therapy to the collection of stem cells with consequent depletion of regulatory T cells after the conditioning regimen could explain some of the unusual autoimmune complications reported in patients receiving bortezomib prior to ASCT. In addition, this patient developed a secondary MGUS post-ASCT, which may have also contributed to the AVWS. To the best of our knowledge, this is the first case of post-ASCT AVWS reported. Prospective data is needed to better elucidate the mechanisms by which these unusual complications occur in patients receiving bortezomib prior to ASCT.

A novel deletion mutation is recurrent in von Willebrand disease types 1 and 3.

PubMed

Sutherland, Megan S; Cumming, Anthony M; Bowman, Mackenzie; Bolton-Maggs, Paula H B; Bowen, Derrick J; Collins, Peter W; Hay, Charles R M; Will, Andrew M; Keeney, Stephen

2009-07-30

Direct sequencing of VWF genomic DNA in 21 patients with type 3 von Willebrand disease (VWD) failed to reveal a causative homozygous or compound heterozygous VWF genotype in 5 cases. Subsequent analysis of VWF mRNA led to the discovery of a deletion (c.221-977_532 + 7059del [p.Asp75_Gly178del]) of VWF in 7 of 12 white type 3 VWD patients from 6 unrelated families. This deletion of VWF exons 4 and 5 was absent in 9 patients of Asian origin. We developed a genomic DNA-based assay for the deletion, which also revealed its presence in 2 of 34 type 1 VWD families, segregating with VWD in an autosomal dominant fashion. The deletion was associated with a specific VWF haplotype, indicating a possible founder origin. Expression studies indicated markedly decreased secretion and defective multimerization of the mutant VWF protein. Further studies have found the mutation in additional type 1 VWD patients and in a family expressing both type 3 and type 1 VWD. The c.221-977_532 + 7059del mutation represents a previously unreported cause of both types 1 and 3 VWD. Screening for this mutation in other type 1 and type 3 VWD patient populations is required to elucidate further its overall contribution to VWD arising from quantitative deficiencies of VWF.

The important role of von Willebrand factor in platelet-derived FVIII gene therapy for murine hemophilia A in the presence of inhibitory antibodies.

PubMed

Shi, Q; Schroeder, J A; Kuether, E L; Montgomery, R R

2015-07-01

Our previous studies have demonstrated that targeting FVIII expression to platelets results in FVIII storage together with von Willebrand factor (VWF) in platelet α-granules and that platelet-derived FVIII (2bF8) corrects the murine hemophilia A phenotype even in the presence of high-titer anti-FVIII inhibitory antibodies (inhibitors). To explore how VWF has an impact on platelet gene therapy for hemophilia A with inhibitors. 2bF8 transgenic mice in the FVIII(-/-) background (2bF8(tg+/-) F8(-/-) ) with varying VWF phenotypes were used in this study. Animals were analyzed by VWF ELISA, FVIII activity assay, Bethesda assay and tail clip survival test. Only 18% of 2bF8(tg+/-) F8(-/-) VWF(-/-) animals, in which VWF was deficient, survived the tail clip challenge with inhibitor titers of 3-8000 BU mL(-1) . In contrast, 82% of 2bF8(tg+/-) F8(-/-) VWF(+/+) mice, which had normal VWF levels, survived tail clipping with inhibitor titers of 10-50,000 BU mL(-1) . All 2bF8(tg+/-) F8(-/-) VWF(-/-) mice without inhibitors survived tail clipping and no VWF(-/-) F8(-/-) mice survived this challenge. Because VWF is synthesized by endothelial cells and megakaryocytes and is distributed in both plasma and platelets in peripheral blood, we further investigated the effect of each compartment of VWF on platelet-FVIII gene therapy for hemophilia A with inhibitors. In the presence of inhibitors, 42% of animals survived tail clipping in the group with plasma-VWF and 50% survived in the platelet-VWF group. VWF is essential for platelet gene therapy for hemophilia A with inhibitors. Both platelet-VWF and plasma-VWF are required for optimal platelet-derived FVIII gene therapy for hemophilia A in the presence of inhibitors. © 2015 International Society on Thrombosis and Haemostasis.

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

Gianetti, Jacopo; Parri, Maria Serena; Della Pina, Francesca; Marchi, Federica; Koni, Endrin; De Caterina, Alberto; Maffei, Stefano; Berti, Sergio

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.

Von Willebrand Factor Deposition and ADAMTS-13 Consumption in Allograft Tissue of Thrombotic Microangiopathy-like Disorder After Living Donor Liver Transplantation: A Case Report.

PubMed

Nakanuma, S; Miyashita, T; Hayashi, H; Ohbatake, Y; Takamura, H; Okazaki, M; Yamaguchi, T; Sakai, S; Makino, I; Oyama, K; Tajima, H; Ninomiya, I; Fushida, S; Ohta, T

2017-09-01

Thrombotic microangiopathy (TMA) pathogenesis after living donor liver transplantation (LDLT) is thought to be caused by release of unusually large von Willebrand factor multimers (UL-vWFMs) resulting from sinusoidal endothelial cell damage and induction of platelet adhesion and aggregation. A decrease in a disintegrin-like and metalloproteinase with thrombospondin type 1 motifs-13 (ADAMTS-13) that cleave UL-vWFMs might cause excessive UL-vWFMs activity and result in platelet thrombus formation. However, this phenomenon has not undergone a full pathologic assessment. A 60-year-old man was diagnosed with hepatitis C-related end-stage cirrhosis. His son was the donor, and he underwent LDLT. On postoperative day 44, his laboratory findings met most TMA diagnostic criteria, and he was diagnosed with TMA-like disorder (TMALD). Localization of CD42b as a platelet marker, vWF, and ADAMTS-13 in allograft tissue of this patient were evaluated using immunohistochemistry. CD42b expression was observed as platelet aggregates attached to hepatocytes or within the hepatocyte cytoplasm, a morphology called extravasated platelet aggregation (EPA). vWF expression was observed mainly as deposited compact clusters, and ADAMTS-13 expression resembled distinct dots throughout the liver tissue. These findings suggest that EPA indicated sinusoidal endothelial cell damage followed by detachment, and vWF deposition resulted from UL-vWFM oversynthesis. ADAMTS-13 might be consumed in the allograft tissue to cleave UL-vWFMs, but ADAMTS-13 levels might be insufficient to cleave all the deposited UL-vWFMs. We present the case of an LDLT recipient diagnosed with TMALD using blood tests, which showed the presence of TMA pathogenesis in the allograft. Copyright © 2017 Elsevier Inc. All rights reserved.

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

Comparison of several von Willebrand factor (VWF) activity assays for monitoring patients undergoing treatment with VWF/FVIII concentrates: improved performance with a new modified automated method.

PubMed

Hillarp, A; Friedman, K D; Adcock-Funk, D; Tiefenbacher, S; Nichols, W L; Chen, D; Stadler, M; Schwartz, B A

2015-11-01

The ability of von Willebrand factor (VWF) to bind platelet GP Ib and promote platelet plug formation is measured in vitro using the ristocetin cofactor (VWF:RCo) assay. Automated assay systems make testing more accessible for diagnosis, but do not necessarily improve sensitivity and accuracy. We assessed the performance of a modified automated VWF:RCo assay protocol for the Behring Coagulation System (BCS(®) ) compared to other available assay methods. Results from different VWF:RCo assays in a number of specialized commercial and research testing laboratories were compared using plasma samples with varying VWF:RCo activities (0-1.2 IU mL(-1) ). Samples were prepared by mixing VWF concentrate or plasma standard into VWF-depleted plasma. Commercially available lyophilized standard human plasma was also studied. Emphasis was put on the low measuring range. VWF:RCo accuracy was calculated based on the expected values, whereas precision was obtained from repeated measurements. In the physiological concentration range, most of the automated tests resulted in acceptable accuracy, with varying reproducibility dependent on the method. However, several assays were inaccurate in the low measuring range. Only the modified BCS protocol showed acceptable accuracy over the entire measuring range with improved reproducibility. A modified BCS(®) VWF:RCo method can improve sensitivity and thus enhances the measuring range. Furthermore, the modified BCS(®) assay displayed good precision. This study indicates that the specific modifications - namely the combination of increased ristocetin concentration, reduced platelet content, VWF-depleted plasma as on-board diluent and a two-curve calculation mode - reduces the issues seen with current VWF:RCo activity assays. © 2015 John Wiley & Sons Ltd.

von Willebrand Factor Test

MedlinePlus

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Elevated levels of von Willebrand factor and high mobility group box 1 (HMGB1) are associated with disease severity and clinical outcome of scrub typhus.

PubMed

Chen, Hongliu; Ning, Zong; Qiu, Ying; Liao, Yuanli; Chang, Haihua; Ai, Yuanyuan; Wei, Yinghua; Deng, Yiming; Shen, Ying

2017-08-01

This study aimed to investigate whether von Willebrand factor (vWF) and high mobility group box 1 (HMGB1) are associated with the severity and clinical outcome of scrub typhus and to seek novel biomarkers for surveillance and prediction of the prognosis of this infection. Serum concentrations of vWF and HMGB1 were measured twice by ELISA for scrub typhus patients (n=103), once prior to doxycycline therapy and then on day 7 of doxycycline therapy; concentrations were measured once for healthy controls (n=32). Among the total 103 patients enrolled, 38 had disease complicated by multiple organ dysfunction syndrome (MODS). Serum concentrations of vWF and HMGB1 were significantly higher in all the patients than in the healthy controls, both prior to doxycycline treatment and on day 7 of doxycycline treatment (p<0.01). Furthermore, serum levels of vWF, HMGB1, and creatinine (SCr) in the patients with MODS increased distinctly, while the platelet (PLT) count diminished markedly compared to the levels in patients without MODS (p<0.01). The concentration of vWF was positively correlated with that of HMGB1 (r=0.764, p<0.001) and SCr (r=0.528, p<0.001), but negatively correlated with the PLT count (r=-0.632, p<0.001). Both HMGB1 and vWF were significantly associated with mortality in scrub typhus (area under the curve (AUC)=0.864, p=0.001, and AUC=0.862, p=0.001, respectively). Elevated levels of vWF and HMGB1 are associated with the severity and clinical outcome of scrub typhus. These represent possible new biomarkers for use in the assessment and prognostic prediction of this infection. Copyright © 2017 The Author(s). Published by Elsevier Ltd.. All rights reserved.

Platelet sequestration and activation during GalTKO.hCD46 pig lung perfusion by human blood is primarily mediated by GPIb, GPIIb/IIIa, and von Willebrand Factor.

PubMed

Burdorf, L; Riner, A; Rybak, E; Salles, I I; De Meyer, S F; Shah, A; Quinn, K J; Harris, D; Zhang, T; Parsell, D; Ali, F; Schwartz, E; Kang, E; Cheng, X; Sievert, E; Zhao, Y; Braileanu, G; Phelps, C J; Ayares, D L; Deckmyn, H; Pierson, R N; Azimzadeh, A M; Dandro, Amy; Karavi, Kasinath

2016-05-01

Here, we ask whether platelet GPIb and GPIIb/IIIa receptors modulate platelet sequestration and activation during GalTKO.hCD46 pig lung xenograft perfusion. GalTKO.hCD46 transgenic pig lungs were perfused with heparinized fresh human blood. Results from perfusions in which αGPIb Fab (6B4, 10 mg/l blood, n = 6), αGPIIb/IIIa Fab (ReoPro, 3.5 mg/l blood, n = 6), or both drugs (n = 4) were administered to the perfusate were compared to two additional groups in which the donor pig received 1-desamino-8-d-arginine vasopressin (DDAVP), 3 μg/kg (to pre-deplete von Willebrand Factor (pVWF), the main GPIb ligand), with or without αGPIb (n = 6 each). Platelet sequestration was significantly delayed in αGPIb, αGPIb+DDAVP, and αGPIb+αGPIIb/IIIa groups. Median lung "survival" was significantly longer (>240 vs. 162 min reference, p = 0.016), and platelet activation (as CD62P and βTG) were significantly inhibited, when pigs were pre-treated with DDAVP, with or without αGPIb Fab treatment. Pulmonary vascular resistance rise was not significantly attenuated in any group, and was associated with residual thromboxane and histamine elaboration. The GPIb-VWF and GPIIb/IIIa axes play important roles in platelet sequestration and coagulation cascade activation during GalTKO.hCD46 lung xenograft injury. GPIb blockade significantly reduces platelet activation and delays platelet sequestration in this xenolung rejection model, an effect amplified by adding αGPIIb/IIIa blockade or depletion of VWF from pig lung. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Relationship between ADAMTS13 activity, von Willebrand factor antigen levels and platelet function in the early and late phases after TIA or ischaemic stroke.

PubMed

McCabe, Dominick J H; Murphy, Stephen J X; Starke, Richard; Harrison, Paul; Brown, Martin M; Sidhu, Paul S; Mackie, Ian J; Scully, Marie; Machin, Samuel J

2015-01-15

Reduced ADAMTS13 activity is seen in thrombotic thrombocytopenic purpura (TTP), and may lead to accumulation of prothrombotic ultra-large von Willebrand factor (ULVWF) multimers in vivo. ADAMTS13 activity and its relationship with VWF antigen (VWF:Ag) levels and platelet function in 'non-TTP related' TIA or ischaemic stroke has not been comprehensively studied. In this prospective pilot observational analytical case-control study, ADAMTS13 activity and VWF:Ag levels were quantified in platelet poor plasma in 53 patients in the early phase (≤ 4 weeks) and 34 of these patients in the late phase (≥ 3 months) after TIA or ischaemic stroke on aspirin. Data were compared with those from 22 controls not on aspirin. The impact of ADAMTS13 on platelet function in whole blood was quantified by measuring Collagen-ADP (C-ADP) and Collagen-Epinephrine closure times on a platelet function analyser (PFA-100(®)). Median ADAMTS13 activity was significantly reduced in the early phase (71.96% vs. 95.5%, P <0.01) but not in the late phase after TIA or stroke compared with controls (86.3% vs. 95.5%, P=0.19). There was a significant inverse relationship between ADAMTS13 activity and VWF:Ag levels in the early phase (r=-0.31; P=0.024), but not in the late phase after TIA or stroke (P=0.74). There was a positive correlation between ADAMTS13 activity and C-ADP closure times in early phase patients only, likely mediated via VWF:Ag levels. ADAMTS13 activity is reduced and VWF:Ag expression is increased within 4 weeks of TIA or ischaemic stroke onset, and can promote enhanced platelet adhesion and aggregation in response to stimulation with collagen and ADP via VWF-mediated pathways. These data improve our understanding of the dynamic haemostatic and thrombotic profiles of ischaemic cerebrovascular disease (CVD) patients, and are important in view of the potential future role that ADAMTS13 may have to play as an anti-thrombotic agent in CVD. Copyright © 2014 Elsevier B.V. All rights

Influence of atrial fibrillation on plasma von willebrand factor, soluble E-selectin, and N-terminal pro B-type natriuretic peptide levels in systolic heart failure.

PubMed

Freestone, Bethan; Gustafsson, Finn; Chong, Aun Yeong; Corell, Pernille; Kistorp, Caroline; Hildebrandt, Per; Lip, Gregory Y H

2008-05-01

Endothelial dysfunction is present in patients with heart failure (HF) due to left ventricular systolic dysfunction, as well as in patients with atrial fibrillation (AF) who have normal cardiac function. It is unknown whether AF influences the degree of endothelial dysfunction in patients with systolic HF. We measured levels of plasma von Willebrand factor (vWF) and E-selectin (as indexes of endothelial damage/dysfunction and endothelial activation, respectively; both enzyme-linked immunosorbent assay) in patients with AF and HF (AF-HF), who were compared to patients with sinus rhythm and HF (SR-HF), as well as in age-matched, healthy, control subjects. We also assessed the relationship of vWF and E-selectin to plasma N-terminal pro B-type natriuretic peptide (NTpro-BNP), a marker for HF severity and prognosis. One hundred ninety patients (73% men; mean age, 69.0 +/- 10.1 years [+/- SD]) with systolic HF were studied, who were compared to 117 healthy control subjects: 52 subjects (27%) were in AF, while 138 subjects (73%) were in sinus rhythm. AF-HF patients were older than SR-HF patients (p = 0.046), but left ventricular ejection fraction and New York Heart Association class were similar. There were significant differences in NT-proBNP (p < 0.0001) and plasma vWF (p = 0.003) between patients and control subjects. On Tukey post hoc analysis, AF-HF patients had significantly increased NT-proBNP (p < 0.001) and vWF (p = 0.0183) but not E-selectin (p = 0.071) levels when compared to SR-HF patients. On multivariate analysis, the presence of AF was related to plasma vWF levels (p = 0.018). Plasma vWF was also significantly correlated with NT-proBNP levels (Spearman r = 0.139; p = 0.017). There is evidence of greater endothelial damage/dysfunction in AF-HF patients when compared to SR-HF patients. The clinical significance of this is unclear but may have prognostic value.

ATZ11 recognizes not only Z-α1-antitrypsin-polymers and complexed forms of non-Z-α1-antitrypsin but also the von Willebrand factor.

PubMed

Goltz, Diane; Hittetiya, Kanishka; Yadegari, Hamideh; Driesen, Julia; Kirfel, Jutta; Neuhaus, Thomas; Steiner, Susanne; Esch, Christiane; Bedorf, Jörg; Hertfelder, Hans-Jörg; Fischer, Hans-Peter

2014-01-01

The ATZ11 antibody has been well established for the identification of α1-anti-trypsin (AAT) molecule type PiZ (Z-AAT) in blood samples and liver tissue. In this study, we systematically analyzed the antibody for additional binding sites in human tissue. Ultrastructural ATZ11 binding was investigated immunoelectron microscopically in human umbilical vein endothelial cells (HUVECs) and in platelets of a healthy individual. Human embryonic kidney (HEK293) cells were transiently transfected with Von Willebrand factor (VWF) and analyzed immunocytochemically using confocal microscopy and SDS-PAGE electrophoresis followed by western blotting (WB). Platelets and serum samples of VWF-competent and VWF-deficient patients were investigated using native PAGE and SDS-PAGE electrophoresis followed by WB. The specificity of the ATZ11 reaction was tested immunohistochemically by extensive antibody-mediated blocking of AAT- and VWF-antigens. ATZ11-positive epitopes could be detected in Weibel-Palade bodies (WPBs) of HUVECs and α-granules of platelets. ATZ11 stains pseudo-WBP containing recombinant wild-type VWF (rVWF-WT) in HEK293 cells. In SDS-PAGE electrophoresis followed by WB, anti-VWF and ATZ11 both identified rVWF-WT. However, neither rVWF-WT-multimers, human VWF-multimers, nor serum proteins of VWF-deficient patients were detected using ATZ11 by WB, whereas anti-VWF antibody (anti-VWF) detected rVWF-WT-multimers as well as human VWF-multimers. In human tissue specimens, AAT-antigen blockade using anti-AAT antibody abolished ATZ11 staining of Z-AAT in a heterozygous AAT-deficient patient, whereas VWF-antigen blockade using anti-VWF abolished ATZ11 staining of endothelial cells and megakaryocytes. ATZ11 reacts with cellular bound and denatured rVWF-WT and human VWF as shown using immunocytochemistry and subsequent confocal imaging, immunoelectron microscopy, SDS-PAGE and WB, and immunohistology. These immunoreactions are independent of the binding of Z-AAT-molecules and non

ATZ11 Recognizes Not Only Z-α1-Antitrypsin-Polymers and Complexed Forms of Non-Z-α1-Antitrypsin but Also the von Willebrand Factor

PubMed Central

Yadegari, Hamideh; Driesen, Julia; Kirfel, Jutta; Neuhaus, Thomas; Steiner, Susanne; Esch, Christiane; Bedorf, Jörg; Hertfelder, Hans-Jörg; Fischer, Hans-Peter

2014-01-01

Aims The ATZ11 antibody has been well established for the identification of α1-anti-trypsin (AAT) molecule type PiZ (Z-AAT) in blood samples and liver tissue. In this study, we systematically analyzed the antibody for additional binding sites in human tissue. Methods and Results Ultrastructural ATZ11 binding was investigated immunoelectron microscopically in human umbilical vein endothelial cells (HUVECs) and in platelets of a healthy individual. Human embryonic kidney (HEK293) cells were transiently transfected with Von Willebrand factor (VWF) and analyzed immunocytochemically using confocal microscopy and SDS-PAGE electrophoresis followed by western blotting (WB). Platelets and serum samples of VWF-competent and VWF-deficient patients were investigated using native PAGE and SDS-PAGE electrophoresis followed by WB. The specificity of the ATZ11 reaction was tested immunohistochemically by extensive antibody-mediated blocking of AAT- and VWF-antigens. ATZ11-positive epitopes could be detected in Weibel-Palade bodies (WPBs) of HUVECs and α-granules of platelets. ATZ11 stains pseudo-WBP containing recombinant wild-type VWF (rVWF-WT) in HEK293 cells. In SDS-PAGE electrophoresis followed by WB, anti-VWF and ATZ11 both identified rVWF-WT. However, neither rVWF-WT-multimers, human VWF-multimers, nor serum proteins of VWF-deficient patients were detected using ATZ11 by WB, whereas anti-VWF antibody (anti-VWF) detected rVWF-WT-multimers as well as human VWF-multimers. In human tissue specimens, AAT-antigen blockade using anti-AAT antibody abolished ATZ11 staining of Z-AAT in a heterozygous AAT-deficient patient, whereas VWF-antigen blockade using anti-VWF abolished ATZ11 staining of endothelial cells and megakaryocytes. Conclusions ATZ11 reacts with cellular bound and denatured rVWF-WT and human VWF as shown using immunocytochemistry and subsequent confocal imaging, immunoelectron microscopy, SDS-PAGE and WB, and immunohistology. These immunoreactions are independent of

Generation and validation of the Condensed MCMDM-1VWD Bleeding Questionnaire for von Willebrand disease.

PubMed

Bowman, M; Mundell, G; Grabell, J; Hopman, W M; Rapson, D; Lillicrap, D; James, P

2008-12-01

Given the challenges involved in obtaining accurate bleeding histories, attempts at standardization have occurred and the value of quantifying hemorrhagic symptoms has been recognized. An extensive validated bleeding questionnaire (MCMDM-1VWD) was condensed by eliminating all details that did not directly affect the bleeding score (BS) and the correlation between the two versions was tested. Additionally, the diagnostic utility of the condensed version was prospectively tested. Data on 259 individuals who were administered the questionnaire are presented here; 217 being prospectively investigated for von Willebrand disease (VWD) (group 1) and 42 previously known to have type 1, 2 or 3 VWD (group 2). Of the 217 prospectively investigated, 35 had positive BS (> or =4) and 182 had negative scores. Seven individuals (all with positive BS) had laboratory results consistent with type 1 VWD. This results in a sensitivity of 100% and a specificity of 87%. The positive predictive value is 0.20 and the negative predictive value is 1. The correlation between the full MCMDM-1VWD and condensed versions is excellent (Spearman's 0.97, P < 0.001, linear regression r(2) = 96.4). Inter-observer reliability for the condensed version is reasonable (Spearman's 0.72, P < 0.001 and intra-class correlation coefficient 0.805, P < 0.001). There was a significant difference in BS between subtypes of VWD, with type 3 > type 2 > type 1 VWD (anova P < 0.001). There is a strong inverse relationship between VWF:Ag level and BS (Spearman's -0.411, P < 0.001). The Condensed MCMDM-1VWD Bleeding Questionnaire is an efficient, effective tool in the evaluation of patients for VWD.

Left Ventricular Assist Device Design Reduces von Willebrand Factor Degradation: A Comparative Study Between the HeartMate II and the EVAHEART Left Ventricular Assist System.

PubMed

Bartoli, Carlo R; Kang, Jooeun; Zhang, David; Howard, Jessica; Acker, Michael; Atluri, Pavan; Motomura, Tadashi

2017-04-01

Supraphysiologic shear stress from continuous-flow left ventricular assist devices (LVADs) accelerates von Willebrand factor (vWF) degradation and predisposes patients to nonsurgical bleeding. It is unknown whether unique design characteristics of LVADs differentially affect vWF degradation. We tested the hypothesis that the centrifugal-flow EVAHEART (Evaheart, Houston, TX) left ventricular assist system (LVAS), which was designed to minimize shear stress (low operational revolutions per minute [rpm], larger flow gaps, low shear stress, flat H-Q curve), reduced vWF degradation versus the axial-flow HeartMate II (Thoratec, Pleasanton, CA) LVAD. Whole human blood was obtained from volunteer donors (n = 22). Blood was circulated for 12 hours in mock circulatory loops through a HeartMate II (n = 10; 11,400 rpm, 6.3 ± 0.8 L/min, 76 ± 2 mm Hg) or an EVAHEART LVAS (n = 12; 2,300 rpm, 5.7 ± 0.1 L/min, 80 ± 1 mm Hg). vWF degradation was characterized with electrophoresis and immunoblotting for large vWF multimers and 11 vWF degradation fragments. The HeartMate II eliminated large vWF multimers and significantly (p < 0.05) increased 10 of 11 vWF degradation fragments at 6 and 12 hours. The increase was approximately 2.0-fold at 6 hours and 2.2-fold at 12 hours. In contrast, the EVAHEART LVAS modestly reduced large vWF multimers and significantly increased 5 of 11 and 8 of 11 vWF degradation fragments at 6 and 12 hours, respectively. The increase was approximately 1.5-fold at 6 hours and 1.7-fold at 12 hours. The EVAHEART LVAS caused significantly less degradation (p < 0.01) than the HeartMate II of the 140 kDa vWF fragment (cleavage product of ADAMTS-13, the vWF protease). The EVAHEART LVAS caused significantly less vWF degradation than the HeartMate II in a mock circulatory loop with whole human blood. LVAD design features may minimize vWF degradation. These data may inform the design and operation of next-generation LVADs to minimize blood trauma. Copyright © 2017

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

Jensen, Gitte S; Lenninger, Miki; Ero, Michael P; Benson, Kathleen F

2016-01-01

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. 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. 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. The data suggest that nattokinase consumption in a North American population is associated with beneficial changes to BP in a hypertensive population

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

Inhibition of ADAMTS-13 by Doxycycline Reduces von Willebrand Factor Degradation During Supraphysiological Shear Stress: Therapeutic Implications for Left Ventricular Assist Device-Associated Bleeding.

PubMed

Bartoli, Carlo R; Kang, Jooeun; Restle, David J; Zhang, David M; Shabahang, Cameron; Acker, Michael A; Atluri, Pavan

2015-11-01

The aim of this study was to investigate a potential therapy for left ventricular assist device (LVAD)-associated bleeding. Nonsurgical bleeding is the most frequent complication of LVAD support. Recent evidence has demonstrated that supraphysiological shear stress from continuous-flow LVADs accelerates von Willebrand factor (vWF) metabolism by the action of a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13 (ADAMTS-13) (the vWF protease). An acquired vWF deficiency causes bleeding. This suggests that ADAMTS-13 is a clinical target to reduce vWF degradation. We tested the hypothesis that inhibition of ADAMTS-13 with doxycycline, an inexpensive, clinically approved drug, reduces vWF degradation during shear stress. Whole blood was collected from human donors (n = 15), and purified, recombinant ADAMTS-13 protein was obtained. An enzyme-linked immunosorbent assay (ELISA) was used to quantify the dose relationship between doxycycline and ADAMTS-13 activity prior to shear stress (n = 10). To determine the effect of shear stress, plasma and recombinant ADAMTS-13 were exposed to LVAD-like supraphysiological shear stress (approximately 175 dyne/cm(2)). vWF multimers and degradation fragments were characterized with electrophoresis and immunoblotting (n = 10). Förster resonance energy transfer was used to quantify plasma ADAMTS-13 activity (n = 10). An ELISA was used to quantify vWF:collagen binding activity. Platelet aggregometry was performed with adenosine 5'-diphosphate, collagen, and ristocetin (vWF-platelet pathway) agonism (n = 10). Doxycycline significantly decreased plasma ADAMTS-13 activity (p = 0.01) and the activity of recombinant human ADAMTS-13 protein by 21%. After plasma was exposed to shear stress, the same pattern of vWF degradation was observed as previously reported for LVAD patients, and vWF:collagen binding activity decreased significantly (p = 0.002). Doxycycline significantly decreased ADAMTS-13 activity (p = 0.04) and

Haemodynamic responses and changes of haemostatic risk factors in cold-adapted humans.

PubMed

De Lorenzo, F; Kadziola, Z; Mukherjee, M; Saba, N; Kakkar, V V

1999-09-01

Epidemiological studies have shown an increase in acute myocardial infarctions or deaths due to myocardial infarction in colder weather; the mechanisms most likely involve increased blood levels of haemostatic risk factors, and increases in arterial blood pressure and heart rate. We studied the relationship between cold adaptation, haemostatic risk factors and haemodynamic variables. Cold adaptation was obtained by a programme of immersion of the whole body up to the neck in a water-filled bath, the temperature of which was gradually decreased from 22 degrees C to 14 degrees C, time of exposure being increased from 5 to 20 min over a period of 90 days. We studied 428 patients (44% men) and measured blood levels of fibrinogen, plasminogen activator inhibitor 1 (PAI-1), tissue plasminogen activator antigen (t-PA), plasma viscosity, von Willebrand factor, D-dimer and platelet count, both at baseline and after 90 days of daily immersion. There were significant reductions in von Willebrand factor (-3%; p < 0.001), and plasma viscosity (-3.0 s; p < 0.001), and a mild but significant increase in PAI-1 (+0.3 IU/ml; p = 0.02). The pressure rate product (systolic blood pressure x heart rate) was also significantly lower after cold adaptation (-310; p = 0.004). Cold adaptation, compared with exposure to cold weather, induces different haemodynamic responses and changes of blood levels of haemostatic risk factors.

Screening of female family members of von Willebrand disease patients: utility of a modified screening tool in a high-risk population.

PubMed

Faiz, A S; Kaveney, A; Guo, S; Murphy, S; Philipp, C S

2017-09-01

Family members of Von Willebrand disease (VWD) patients may have low levels of VWF without major bleeding episodes and often remain undiagnosed. The purpose of this study was to assess the utility of a modified Screening Tool in identifying previously untested reproductive age female family members of VWD patients for haemostatic evaluation. Ninety-four reproductive age women including 41 previously untested family members of VWD patients, 26 previously diagnosed VWD patients and 27 healthy controls were administered a modified Screening Tool and had blood drawn for CBC, ferritin, and VWF testing. Participants completed a pictorial blood assessment chart (PBAC) with menses. The modified Screening Tool was positive in 32% family members, 77% VWD patients, and 19% controls (P < 0.001). Combined with low ferritin, the modified Screening Tool was positive in 66% family members, 92% VWD patients, and 44% controls (P = 0.001). In family members, incorporating low ferritin with the modified Screening Tool resulted in a sensitivity of 86% (95% CI, 42-100) and negative predictive value of 93% (95% CI, 66-100). In the control group, NPV was between 92% and 95% for the modified Screening Tool and also for the modified Screening Tool combined with low ferritin or a positive PBAC. These data in a racially diverse population suggest the usefulness of a simple, easy to administer modified Screening Tool. In conjunction with ferritin it could be used in a primary care setting to stratify reproductive age women with a family history of VWD for haemostatic evaluation. © 2017 John Wiley & Sons Ltd.

Identification and characterization of a novel P2Y 12 variant in a patient diagnosed with type 1 von Willebrand disease in the European MCMDM-1VWD study.

PubMed

Daly, Martina E; Dawood, Ban B; Lester, William A; Peake, Ian R; Rodeghiero, Francesco; Goodeve, Anne C; Makris, Michael; Wilde, Jonathan T; Mumford, Andrew D; Watson, Stephen P; Mundell, Stuart J

2009-04-23

We investigated whether defects in the P2Y(12) ADP receptor gene (P2RY12) contribute to the bleeding tendency in 92 index cases enrolled in the European MCMDM-1VWD study. A heterozygous mutation, predicting a lysine to glutamate (K174E) substitution in P2Y(12), was identified in one case with mild type 1 von Willebrand disease (VWD) and a VWF defect. Platelets from the index case and relatives carrying the K174E defect changed shape in response to ADP, but showed reduced and reversible aggregation in response to 10 muM ADP, unlike the maximal, sustained aggregation observed in controls. The reduced response was associated with an approximate 50% reduction in binding of [(3)H]2MeS-ADP to P2Y(12), whereas binding to the P2Y(1) receptor was normal. A hemagglutinin-tagged K174E P2Y(12) variant showed surface expression in CHO cells, markedly reduced binding to [(3)H]2MeS-ADP, and minimal ADP-mediated inhibition of forskolin-induced adenylyl cyclase activity. Our results provide further evidence for locus heterogeneity in type 1 VWD.

Perioperative onset of acquired von Willebrand syndrome: Comparison between HVAD, HeartMate II and on-pump coronary bypass surgery.

PubMed

Feldmann, Christina; Zayat, Rashad; Goetzenich, Andreas; Aljalloud, Ali; Woelke, Eva; Maas, Judith; Tewarie, Lachmandath; Schmitz-Rode, Thomas; Autschbach, Ruediger; Steinseifer, Ulrich; Moza, Ajay

2017-01-01

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. 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. 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. 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.

Blood Disorders

MedlinePlus

... become hard, sticky, and shaped like a C. Thalassemia Red blood cell disorder. Von Willebrand Disease Blood ... Hemophilia Hereditary Hemorrhagic Telangiectasia (HHT) Sickle Cell Disease Thalassemia Vitamin K Deficiency Bleeding Von Willebrand Disease Women’s ...

Measurement of Blood Coagulation Factor Synthesis in Cultures of Human Hepatocytes.

PubMed

Heinz, Stefan; Braspenning, Joris

2015-01-01

An important function of the liver is the synthesis and secretion of blood coagulation factors. Within the liver, hepatocytes are involved in the synthesis of most blood coagulation factors, such as fibrinogen, prothrombin, factor V, VII, IX, X, XI, XII, as well as protein C and S, and antithrombin, whereas liver sinusoidal endothelial cells produce factor VIII and von Willebrand factor. Here, we describe methods for the detection and quantification of most blood coagulation factors in hepatocytes in vitro. Hepatocyte cultures indeed provide a valuable tool to study blood coagulation factors. In addition, the generation and expansion of hepatocytes or hepatocyte-like cells may be used in future for cell-based therapies of liver diseases, including blood coagulation factor deficiencies.

Platelet glycoprotein Ibalpha forms catch bonds with human WT vWF but not with type 2B von Willebrand disease vWF.

PubMed

Yago, Tadayuki; Lou, Jizhong; Wu, Tao; Yang, Jun; Miner, Jonathan J; Coburn, Leslie; López, José A; Cruz, Miguel A; Dong, Jing-Fei; McIntire, Larry V; McEver, Rodger P; Zhu, Cheng

2008-09-01

Arterial blood flow enhances glycoprotein Ibalpha (GPIbalpha) binding to vWF, which initiates platelet adhesion to injured vessels. Mutations in the vWF A1 domain that cause type 2B von Willebrand disease (vWD) reduce the flow requirement for adhesion. Here we show that increasing force on GPIbalpha/vWF bonds first prolonged ("catch") and then shortened ("slip") bond lifetimes. Two type 2B vWD A1 domain mutants, R1306Q and R1450E, converted catch bonds to slip bonds by prolonging bond lifetimes at low forces. Steered molecular dynamics simulations of GPIbalpha dissociating from the A1 domain suggested mechanisms for catch bonds and their conversion by the A1 domain mutations. Catch bonds caused platelets and GPIbalpha-coated microspheres to roll more slowly on WT vWF and WT A1 domains as flow increased from suboptimal levels, explaining flow-enhanced rolling. Longer bond lifetimes at low forces eliminated the flow requirement for rolling on R1306Q and R1450E mutant A1 domains. Flowing platelets agglutinated with microspheres bearing R1306Q or R1450E mutant A1 domains, but not WT A1 domains. Therefore, catch bonds may prevent vWF multimers from agglutinating platelets. A disintegrin and metalloproteinase with a thrombospondin type 1 motif-13 (ADAMTS-13) reduced platelet agglutination with microspheres bearing a tridomain A1A2A3 vWF fragment with the R1450E mutation in a shear-dependent manner. We conclude that in type 2B vWD, prolonged lifetimes of vWF bonds with GPIbalpha on circulating platelets may allow ADAMTS-13 to deplete large vWF multimers, causing bleeding.

Platelet GpIbα Binding to von Willebrand Factor Under Fluid Shear: Contributions of the D'D3‐Domain, A1‐Domain Flanking Peptide and O‐Linked Glycans

PubMed Central

Madabhushi, Sri R.; Zhang, Changjie; Kelkar, Anju; Dayananda, Kannayakanahalli M.; Neelamegham, Sriram

2014-01-01

Background Von Willebrand Factor (VWF) A1‐domain binding to platelet receptor GpIbα is an important fluid‐shear dependent interaction that regulates both soluble VWF binding to platelets, and platelet tethering onto immobilized VWF. We evaluated the roles of different structural elements at the N‐terminus of the A1‐domain in regulating shear dependent platelet binding. Specifically, the focus was on the VWF D′D3‐domain, A1‐domain N‐terminal flanking peptide (NFP), and O‐glycans on this peptide. Methods and Results Full‐length dimeric VWF (ΔPro‐VWF), dimeric VWF lacking the D′D3 domain (ΔD′D3‐VWF), and ΔD′D3‐VWF variants lacking either the NFP (ΔD′D3NFP─‐VWF) or just O‐glycans on this peptide (ΔD′D3OG─‐VWF) were expressed. Monomeric VWF‐A1 and D′D3‐A1 were also produced. In ELISA, the apparent dissociation constant (KD) of soluble ΔPro‐VWF binding to immobilized GpIbα (KD≈100 nmol/L) was 50‐ to 100‐fold higher than other proteins lacking the D′D3 domain (KD~0.7 to 2.5 nmol/L). Additionally, in surface plasmon resonance studies, the on‐rate of D′D3‐A1 binding to immobilized GpIbα (kon=1.8±0.4×104 (mol/L)−1·s−1; KD=1.7 μmol/L) was reduced compared with the single VWF‐A1 domain (kon=5.1±0.4×104 (mol/L)−1·s−1; KD=1.2 μmol/L). Thus, VWF‐D′D3 primarily controls soluble VWF binding to GpIbα. In contrast, upon VWF immobilization, all molecular features regulated A1‐GpIbα binding. Here, in ELISA, the number of apparent A1‐domain sites available for binding GpIbα on ΔPro‐VWF was ≈50% that of the ΔD′D3‐VWF variants. In microfluidics based platelet adhesion measurements on immobilized VWF and thrombus formation assays on collagen, human platelet recruitment varied as ΔPro‐VWF<ΔD′D3‐VWF<ΔD′D3NFP─‐VWF<ΔD′D3OG─‐VWF. Conclusions Whereas VWF‐D′D3 is the major regulator of soluble VWF binding to platelet GpIbα, both the D′D3‐domain and N�

Platelet glycoprotein Ibα forms catch bonds with human WT vWF but not with type 2B von Willebrand disease vWF

PubMed Central

Yago, Tadayuki; Lou, Jizhong; Wu, Tao; Yang, Jun; Miner, Jonathan J.; Coburn, Leslie; López, José A.; Cruz, Miguel A.; Dong, Jing-Fei; McIntire, Larry V.; McEver, Rodger P.; Zhu, Cheng

2008-01-01

Arterial blood flow enhances glycoprotein Ibα (GPIbα) binding to vWF, which initiates platelet adhesion to injured vessels. Mutations in the vWF A1 domain that cause type 2B von Willebrand disease (vWD) reduce the flow requirement for adhesion. Here we show that increasing force on GPIbα/vWF bonds first prolonged (“catch”) and then shortened (“slip”) bond lifetimes. Two type 2B vWD A1 domain mutants, R1306Q and R1450E, converted catch bonds to slip bonds by prolonging bond lifetimes at low forces. Steered molecular dynamics simulations of GPIbα dissociating from the A1 domain suggested mechanisms for catch bonds and their conversion by the A1 domain mutations. Catch bonds caused platelets and GPIbα-coated microspheres to roll more slowly on WT vWF and WT A1 domains as flow increased from suboptimal levels, explaining flow-enhanced rolling. Longer bond lifetimes at low forces eliminated the flow requirement for rolling on R1306Q and R1450E mutant A1 domains. Flowing platelets agglutinated with microspheres bearing R1306Q or R1450E mutant A1 domains, but not WT A1 domains. Therefore, catch bonds may prevent vWF multimers from agglutinating platelets. A disintegrin and metalloproteinase with a thrombospondin type 1 motif–13 (ADAMTS-13) reduced platelet agglutination with microspheres bearing a tridomain A1A2A3 vWF fragment with the R1450E mutation in a shear-dependent manner. We conclude that in type 2B vWD, prolonged lifetimes of vWF bonds with GPIbα on circulating platelets may allow ADAMTS-13 to deplete large vWF multimers, causing bleeding. PMID:18725999

A Protocol for the Preparation of Cryoprecipitate and Cryo-depleted Plasma for Proteomic Studies.

PubMed

Sparrow, Rosemary L; Simpson, Richard J; Greening, David W

2017-01-01

Cryoprecipitate is a concentrate of high-molecular-weight plasma proteins that precipitate when frozen plasma is slowly thawed at 1-6 °C. The concentrate contains factor VIII (antihemophilic factor), von Willebrand factor (vWF), fibrinogen, factor XIII, fibronectin, and small amounts of other plasma proteins. Clinical grade preparations of cryoprecipitate are mainly used to treat fibrinogen deficiency caused by acute bleeding or functional abnormalities of the fibrinogen protein. In the past, cryoprecipitate was used to treat von Willebrand disease and hemophilia A (factor VIII deficiency), but the availability of more highly purified coagulation factor concentrates or recombinant protein preparations has superseded the use of cryoprecipitate for these coagulopathies. Cryo-depleted plasma ("cryosupernatant") is the plasma supernatant remaining following removal of the cryoprecipitate from frozen-thawed plasma. It contains all the other plasma proteins and clotting factors present in plasma that remain soluble during cold-temperature thawing of the plasma. This protocol describes the clinical-scale preparation of cryoprecipitate and cryo-depleted plasma for proteomic studies.

von Willebrand Disease

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Von Willebrand disease

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... platelet and vascular function. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine . 25th ed. Philadelphia, ... Florida Cancer Specialists & Research Institute, Wellington, FL. Review provided by ...

von Willebrand Disease

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Molecular modelling of the Norrie disease protein predicts a cystine knot growth factor tertiary structure.

PubMed

Meitinger, T; Meindl, A; Bork, P; Rost, B; Sander, C; Haasemann, M; Murken, J

1993-12-01

The X-lined gene for Norrie disease, which is characterized by blindness, deafness and mental retardation has been cloned recently. This gene has been thought to code for a putative extracellular factor; its predicted amino acid sequence is homologous to the C-terminal domain of diverse extracellular proteins. Sequence pattern searches and three-dimensional modelling now suggest that the Norrie disease protein (NDP) has a tertiary structure similar to that of transforming growth factor beta (TGF beta). Our model identifies NDP as a member of an emerging family of growth factors containing a cystine knot motif, with direct implications for the physiological role of NDP. The model also sheds light on sequence related domains such as the C-terminal domain of mucins and of von Willebrand factor.

Incidence and risk factors of bleeding-related adverse events in patients with chronic lymphocytic leukemia treated with ibrutinib

PubMed Central

Lipsky, Andrew H.; Farooqui, Mohammed Z.H.; Tian, Xin; Martyr, Sabrina; Cullinane, Ann M.; Nghiem, Khanh; Sun, Clare; Valdez, Janet; Niemann, Carsten U.; Herman, Sarah E. M.; Saba, Nakhle; Soto, Susan; Marti, Gerald; Uzel, Gulbu; Holland, Steve M.; Lozier, Jay N.; Wiestner, Adrian

2015-01-01

Ibrutinib is associated with bleeding-related adverse events of grade ≤2 in severity, and infrequently with grade ≥3 events. To investigate the mechanisms of bleeding and identify patients at risk, we prospectively assessed platelet function and coagulation factors in our investigator-initiated trial of single-agent ibrutinib for chronic lymphocytic leukemia. At a median follow-up of 24 months we recorded grade ≤2 bleeding-related adverse events in 55% of 85 patients. No grade ≥3 events occurred. Median time to event was 49 days. The cumulative incidence of an event plateaued by 6 months, suggesting that the risk of bleeding decreases with continued therapy. At baseline, von Willebrand factor and factor VIII levels were often high and normalized on treatment. Platelet function measured via the platelet function analyzer (PFA-100™) was impaired in 22 patients at baseline and in an additional 19 patients on ibrutinib (often transiently). Collagen and adenosine diphosphate induced platelet aggregation was tested using whole blood aggregometry. Compared to normal controls, response to both agonists was decreased in all patients with chronic lymphocytic leukemia, whether on ibrutinib or not. Compared to untreated chronic lymphocytic leukemia patients, response to collagen showed a mild further decrement on ibrutinib, while response to adenosine diphosphate improved. All parameters associated with a significantly increased risk of bleeding-related events were present at baseline, including prolonged epinephrine closure time (HR 2.74, P=0.012), lower levels of von Willebrand factor activity (HR 2.73, P=0.009) and factor VIII (HR 3.73, P=0.0004). In conclusion, both disease and treatment-related factors influence the risk of bleeding. Patients at greater risk for bleeding of grade ≤2 can be identified by clinical laboratory tests and counseled to avoid aspirin, non-steroidal anti-inflammatory drugs and fish oils. ClinicalTrials.gov identifier NCT01500733 PMID

Platelet Disorders: MedlinePlus Health Topic

MedlinePlus

... von Willebrand Factor Test (American Association for Clinical Chemistry) What Are Bone Marrow Tests? (National Heart, Lung, and Blood Institute) Treatments and Therapies Splenectomy (Mayo Foundation for Medical Education and Research) Also in Spanish What Is a Blood Transfusion? ( ...

77 FR 58849 - Prescription Drug User Fee Act Patient-Focused Drug Development; Public Meeting and Request for...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-09-24

... the impact of the disease on patients, the spectrum of severity for those who have the disease, the... glomerular diseases. Narcolepsy. Huntington's Disease. Depression. Autism. Peripheral neuropathy.... Cancer and depression. Clotting disorders (e.g., hemophilia A (factor VIII deficiency) and von Willebrand...

Transforming growth factor (TGF. beta. ) decreases the proliferation of human bone marrow fibroblasts by inhibiting the platelet-derived growth factor (PDGF) binding

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bryckaert, M.C.; Tobelem, G.; Lindroth, M.

1988-12-01

Human bone marrow fibroblasts were cultivated and characterized by immunofluorescent staining and electron microscopy. Their interactions with PDGF and TGF{beta} were studied. While a positive intracellular antifibronectin staining was observed, the cultured cells were not labeled with specific antibodies toward factor VIII von Willebrand factor (F VIII/vWF), desmin, and macrophage antigen. The binding of pure human PDGF to the cultured bone marrow fibroblasts was investigated. Addition of an excess of unlabeled PDGF decreased the binding to 75 and 80%, which means that the nonspecific binding represented 20-25% of total binding, whereas epidermal growth factor (EGF) had no effect. Two classesmore » of sites were detected by Scatchard analysis. The stimulation of DNA synthesis of PDGF was quantified by ({sup 3}H)thymidine incorporation. The results suggested that PDGF and TGF{beta} could modulate the growth of bone marrow fibroblasts.« less

Mice lacking the extracellular matrix protein MAGP1 display delayed thrombotic occlusion following vessel injury

PubMed Central

Werneck, Claudio C.; Vicente, Cristina P.; Weinberg, Justin S.; Shifren, Adrian; Pierce, Richard A.; Broekelmann, Thomas J.; Tollefsen, Douglas M.

2008-01-01

Mice lacking the extracellular matrix protein microfibril-associated glycoprotein-1 (MAGP1) display delayed thrombotic occlusion of the carotid artery following injury as well as prolonged bleeding from a tail vein incision. Normal occlusion times were restored when recombinant MAGP1 was infused into deficient animals prior to vessel wounding. Blood coagulation was normal in these animals as assessed by activated partial thromboplastin time and prothrombin time. Platelet number was lower in MAGP1-deficient mice, but the platelets showed normal aggregation properties in response to various agonists. MAGP1 was not found in normal platelets or in the plasma of wild-type mice. In ligand blot assays, MAGP1 bound to fibronectin, fibrinogen, and von Willebrand factor, but von Willebrand factor was the only protein of the 3 that bound to MAGP1 in surface plasmon resonance studies. These findings show that MAGP1, a component of microfibrils and vascular elastic fibers, plays a role in hemostasis and thrombosis. PMID:18281502

Transport physics and biorheology in the setting of hemostasis and thrombosis.

PubMed

Brass, L F; Diamond, S L

2016-05-01

The biophysics of blood flow can dictate the function of molecules and cells in the vasculature with consequent effects on hemostasis, thrombosis, embolism, and fibrinolysis. Flow and transport dynamics are distinct for (i) hemostasis vs. thrombosis and (ii) venous vs. arterial episodes. Intraclot transport changes dramatically the moment hemostasis is achieved or the moment a thrombus becomes fully occlusive. With platelet concentrations that are 50- to 200-fold greater than platelet-rich plasma, clots formed under flow have a different composition and structure compared with blood clotted statically in a tube. The platelet-rich, core/shell architecture is a prominent feature of self-limiting hemostatic clots formed under flow. Importantly, a critical threshold concentration of surface tissue factor is required for fibrin generation under flow. Once initiated by wall-derived tissue factor, thrombin generation and its spatial propagation within a clot can be modulated by γ'-fibrinogen incorporated into fibrin, engageability of activated factor (FIXa)/activated FVIIIa tenase within the clot, platelet-derived polyphosphate, transclot permeation, and reduction of porosity via platelet retraction. Fibrin imparts tremendous strength to a thrombus to resist embolism up to wall shear stresses of 2400 dyne cm(-2) . Extreme flows, as found in severe vessel stenosis or in mechanical assist devices, can cause von Willebrand factor self-association into massive fibers along with shear-induced platelet activation. Pathological von Willebrand factor fibers are A Disintegrin And Metalloprotease with ThromboSpondin-1 domain 13 resistant but are a substrate for fibrin generation due to FXIIa capture. Recently, microfluidic technologies have enhanced the ability to interrogate blood in the context of stenotic flows, acquired von Willebrand disease, hemophilia, traumatic bleeding, and drug action. © 2016 International Society on Thrombosis and Haemostasis.

Incidence and risk factors of bleeding-related adverse events in patients with chronic lymphocytic leukemia treated with ibrutinib.

PubMed

Lipsky, Andrew H; Farooqui, Mohammed Z H; Tian, Xin; Martyr, Sabrina; Cullinane, Ann M; Nghiem, Khanh; Sun, Clare; Valdez, Janet; Niemann, Carsten U; Herman, Sarah E M; Saba, Nakhle; Soto, Susan; Marti, Gerald; Uzel, Gulbu; Holland, Steve M; Lozier, Jay N; Wiestner, Adrian

2015-12-01

Ibrutinib is associated with bleeding-related adverse events of grade ≤ 2 in severity, and infrequently with grade ≥ 3 events. To investigate the mechanisms of bleeding and identify patients at risk, we prospectively assessed platelet function and coagulation factors in our investigator-initiated trial of single-agent ibrutinib for chronic lymphocytic leukemia. At a median follow-up of 24 months we recorded grade ≤ 2 bleeding-related adverse events in 55% of 85 patients. No grade ≥ 3 events occurred. Median time to event was 49 days. The cumulative incidence of an event plateaued by 6 months, suggesting that the risk of bleeding decreases with continued therapy. At baseline, von Willebrand factor and factor VIII levels were often high and normalized on treatment. Platelet function measured via the platelet function analyzer (PFA-100™) was impaired in 22 patients at baseline and in an additional 19 patients on ibrutinib (often transiently). Collagen and adenosine diphosphate induced platelet aggregation was tested using whole blood aggregometry. Compared to normal controls, response to both agonists was decreased in all patients with chronic lymphocytic leukemia, whether on ibrutinib or not. Compared to untreated chronic lymphocytic leukemia patients, response to collagen showed a mild further decrement on ibrutinib, while response to adenosine diphosphate improved. All parameters associated with a significantly increased risk of bleeding-related events were present at baseline, including prolonged epinephrine closure time (HR 2.74, P=0.012), lower levels of von Willebrand factor activity (HR 2.73, P=0.009) and factor VIII (HR 3.73, P=0.0004). In conclusion, both disease and treatment-related factors influence the risk of bleeding. Patients at greater risk for bleeding of grade ≤ 2 can be identified by clinical laboratory tests and counseled to avoid aspirin, non-steroidal anti-inflammatory drugs and fish oils. ClinicalTrials.gov identifier NCT01500733

Novel Thrombotic Function of a Human SNP in STXBP5 Revealed by CRISPR/Cas9 Gene Editing in Mice.

PubMed

Zhu, Qiuyu Martin; Ko, Kyung Ae; Ture, Sara; Mastrangelo, Michael A; Chen, Ming-Huei; Johnson, Andrew D; O'Donnell, Christopher J; Morrell, Craig N; Miano, Joseph M; Lowenstein, Charles J

2017-02-01

To identify and characterize the effect of a SNP (single-nucleotide polymorphism) in the STXBP5 locus that is associated with altered thrombosis in humans. GWAS (genome-wide association studies) have identified numerous SNPs associated with human thrombotic phenotypes, but determining the functional significance of an individual candidate SNP can be challenging, particularly when in vivo modeling is required. Recent GWAS led to the discovery of STXBP5 as a regulator of platelet secretion in humans. Further clinical studies have identified genetic variants of STXBP5 that are linked to altered plasma von Willebrand factor levels and thrombosis in humans, but the functional significance of these variants in STXBP5 is not understood. We used CRISPR/Cas9 (clustered regularly interspaced short palindromic repeats/CRISPR-associated 9) techniques to produce a precise mouse model carrying a human coding SNP rs1039084 (encoding human p. N436S) in the STXBP5 locus associated with decreased thrombosis. Mice carrying the orthologous human mutation (encoding p. N437S in mouse STXBP5) have lower plasma von Willebrand factor levels, decreased thrombosis, and decreased platelet secretion compared with wild-type mice. This thrombosis phenotype recapitulates the phenotype of humans carrying the minor allele of rs1039084. Decreased plasma von Willebrand factor and platelet activation may partially explain the decreased thrombotic phenotype in mutant mice. Using precise mammalian genome editing, we have identified a human nonsynonymous SNP rs1039084 in the STXBP5 locus as a causal variant for a decreased thrombotic phenotype. CRISPR/Cas9 genetic editing facilitates the rapid and efficient generation of animals to study the function of human genetic variation in vascular diseases. © 2016 American Heart Association, Inc.

Platelet interactions in thrombosis.

PubMed

Andrews, Robert K; Gardiner, Elizabeth E; Shen, Yang; Berndt, Michael C

2004-01-01

Patho/physiological platelet aggregate (thrombus) formation is initiated by engagement of platelet surface receptors, glycoprotein (GP)Ib-IX-V and GPVI that bind von Willebrand factor or collagen. Although beneficial in response to vascular injury by preventing blood loss (haemostasis), platelet aggregation in a sclerotic coronary artery or other diseased blood vessel (thrombosis) can cause thrombotic diseases like heart attack and stroke. At the molecular level, ligand interactions with GPIb-IX-V or GPVI trigger signalling responses, including elevation of cytosolic Ca2+, dissociation of calmodulin from their cytoplasmic domains, cytoskeletal actin-filament rearrangements, activation of src-family kinases or PI 3-kinase, and 'inside-out' activation of the integrin, alphaIIbbeta3 (GPIIb-llla), that binds von Willebrand factor or fibrinogen and mediates platelet aggregation. Furthermore, emerging evidence supports a topographical co-association of these receptors of the leucine-rich repeat family (GPIb-IX-V) and immunoglobulin superfamily (GPVI) in an adhesive cluster or 'adhesosome'. This arrangement may underlie common mechanisms of initiating thrombus formation in haemostasis or thrombotic disease.

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

A note on derivations of Murray-von Neumann algebras.

PubMed

Kadison, Richard V; Liu, Zhe

2014-02-11

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.

Von Willebrand’s Disease

DTIC Science & Technology

1990-01-01

developing human immunodefi- ANTIFIBRINOLYTIC AGENTS ciency virus (HIV) antibody after receiving Aminocaproic acid (Amicar) and tran- seronegative...8-0 In most Aminocaproic acid can be used in oral patients, treatment is also associated with or intravenous forms. In adults, the oral a rise in the...she was eight years of age. She had no his- caproic acid before the procedure and for tory of bruising or menorrhagia. the next 48 hours. No

von Willebrand Disease (For Parents)

MedlinePlus

[Skip to Content] for Parents Parents site Sitio para padres General Health Growth & Development Infections Diseases & Conditions Pregnancy & Baby Nutrition & Fitness Emotions & Behavior School & Family ...

[Isolation and culture of bovine choriocapillary endothelial cells using paramagnetic beads coated with Lycopersicon esculentum].

PubMed

Swiech-Zubilewicz, A; Soubrane, G; Mascarelli, F

2000-01-01

To establish a pure culture of choriocapillary endothelial cells as a model of angiogenesis in vitro. Bovine choriocapillary endothelial cells (BCEC) were obtained by the method described by Hoffmann et al. (6) using the polystyrene paramagnetic beads coated with Lycopersicon esculentum, which attach specifically to the rest of fucose on the surface of microvascular endothelial cells. The endothelial characteristic of the cultured cells was evaluated by immunocytochemistry using anti von Willebrand factor and anti-CD 31 antibodies. Proliferation and survival of BCEC were tested using haemacytometer of Mallasez. The purity of obtained BCEC culture was confirmed by positive immunocytochemical staining with anti von Willebrand and anti factor CD 31 antibodies in more than 95% of cells. The proliferation of cells in Endothelial Cell Medium resulted in twofold increase of number of cells during 4-day observation period. After reaching the confluence, the cells continued to proliferate with increase of the cell number by 60% during 4-day observation. The use of paramagnetic beads coated with specific lectine provide a pure isolation of BCEC, which can be maintained in culture with preservation of their characteristic.

Enhancing Tumor Drug Delivery by Laser-Activated Vascular Barrier Disruption

DTIC Science & Technology

2009-12-01

found platelet aggregation, thrombus formation and endothelial cell rupture (Fig 1). All these findings demonstrate that PDT damages endothelial...after 0.5 mg/kg verteporfin (i.v.)). (A) 1 h after PDT showing platelet aggregation and thrombus formation; (B) 6 h after PDT showing edema...mechanisms causing thrombi formation. Other mechanisms, such as release of thromboxane from platelets (33) and von Willebrand factor from damaged

Markers of endothelial dysfunction and severity of hypoxaemia in the Eisenmenger syndrome.

PubMed

de P S Soares, Rosangela; Maeda, Nair Y; Bydlowski, Sérgio P; Lopes, Antonio Augusto

2005-10-01

Endothelial dysfunction has been reported in hypoxaemic patients with the Eisenmenger syndrome, but a direct correlation between levels of endothelial markers and the severity of hypoxaemia has not been explored. With this in mind, we compared the levels in the plasma of tissue-type plasminogen activator, thrombomodulin, and von Willebrand factor in 25 patients with the Eisenmenger syndrome. They had a median age of 31 years, and were divided into 2 groups according to their recent clinical history. Thus, 18 patients were stable, being in functional class II or III, seen as outpatients, and having peripheral saturations of oxygen of 89 plus or minus 5 percent. In contrast, 7 patients were unstable, showing episodes of symptoms placing them in functional class IV, requiring care in hospital, and manifesting saturations of oxygen of 77 plus or minus 5 percent. We were able to follow 12 patients, 8 who were stable and 4 unstable, for 24 months. At baseline, levels of von Willebrand factor were higher in the unstable patients when compared to those who were stable, at 142 plus or minus 29 and 110 plus or minus 25 units per decilitre, respectively (p equal to 0.013). This correlated positively with oxygen desaturation (p less than 0.020). The structural abnormalities also correlated positively with the magnitude of hypoxaemia (p less than 0.020). Levels remained higher in the unstable patients throughout the period of follow-up (p equal to 0.006). Tissue-type plasminogen activator was also increased, at 14.3 plus or minus 8.4 versus 6.5 plus or minus 2.7 nanograms per millilitre in controls (p less than 0.001), whereas thrombomodulin was decreased, with values of 14.4 versus 34.6 nanograms per millilitre in controls (p for median values of less than 0.001). There was no correlation with saturations of oxygen. We conclude that measurement of von Willebrand factor, as compared with tissue-type plasminogen activator and thrombomodulin, will prove a better marker of

Life-threatening subdural hematoma after aortic valve replacement in a patient with Heyde syndrome: a case report.

PubMed

Uchida, Tetsuro; Hamasaki, Azumi; Ohba, Eiichi; Yamashita, Atsushi; Hayashi, Jun; Sadahiro, Mitsuaki

2017-08-08

Heyde syndrome is known as a triad of calcific aortic stenosis, anemia due to gastrointestinal bleeding from angiodysplasia, and acquired type 2A von Willebrand disease. This acquired hemorrhagic disorder is characterized by the loss of the large von Willebrand factor multimers due to the shear stress across the diseased aortic valve. The most frequently observed type of bleeding in these patients is mucosal or skin bleeding, such as epistaxis, followed by gastrointestinal bleeding. On the other hand, intracranial hemorrhage complicating Heyde syndrome is extremely rare. A 77-year-old woman presented to our hospital with severe aortic stenosis and severe anemia due to gastrointestinal bleeding and was diagnosed with Heyde syndrome. Although aortic valve replacement was performed without recurrent gastrointestinal bleeding, postoperative life-threatening acute subdural hematoma occurred with a marked midline shift. Despite prompt surgical evacuation of the hematoma, she did not recover consciousness and she died 1 month after the operation. Postoperative subdural hematoma is rare, but it should be kept in mind as a devastating hemorrhagic complication, especially in patients with Heyde syndrome.

Human Platelet Senescence Study.

DTIC Science & Technology

1980-03-01

ability to measure certain enzymes to their oxidation-reduc other enzymes which can be measured by o phosphatase , acid phosphatase , chymotryp...alkaline sin, trypsin, esterases (17)); M use of n A or wheat germ agglutinin in the second etect specific carbohydrate constituents. We have...Von Willebrand factor. Nurden and Caen also demonstrated that GPI was rich in sialic acid (5) and probably responsible for the platelets’ surface

Immunoexpression of vascular endothelial growth factor in periapical granulomas, radicular cysts, and residual radicular cysts.

PubMed

Nonaka, Cassiano Francisco Weege; Maia, Alexandre Pinto; Nascimento, George João Ferreira do; de Almeida Freitas, Roseana; Batista de Souza, Lélia; Galvão, Hébel Cavalcanti

2008-12-01

Our aim was to assess and compare the immunoexpression of vascular endothelial growth factor (VEGF) in periapical granulomas (PGs), radicular cysts (RCs), and residual radicular cysts (RRCs), relating it to the angiogenic index and the intensity of the inflammatory infiltrate. Twenty PGs, 20 RCs, and 10 RRCs were evaluated by immunohistochemistry using anti-VEGF antibody. Angiogenic index was determined by microvessel count (MVC) using anti-von Willebrand factor antibody. The PGs and RCs showed higher expression of VEGF than the RRCs. Lesions presenting few inflammatory infiltrate revealed the lowest immunoexpression of VEGF (P < .05). Irrespective of the intensity of the inflammatory infiltrate, most of the RCs and RRCs showed moderate to strong epithelial expression of VEGF. Lesions showing dense inflammatory infiltrate presented higher MVC indices (P < .05). VEGF expression and MVC did not reveal a significant correlation (P > .05). VEGF is present in periapical inflammatory lesions but at a lower level in RRCs. The expression of this proangiogenic factor is closely related to the intensity of the inflammatory infiltrate in these lesions.

Ambient hemolysis and activation of coagulation is different between HeartMate II and HeartWare left ventricular assist devices.

PubMed

Birschmann, Ingvild; Dittrich, Marcus; Eller, Thomas; Wiegmann, Bettina; Reininger, Armin J; Budde, Ulrich; Strüber, Martin

2014-01-01

Thromboembolic and bleeding events in patients with a left ventricular assist device (LVAD) are still a major cause of complications. Therefore, the balance between anti-coagulant and pro-coagulant factors needs to be tightly controlled. The principle hypothesis of this study is that different pump designs may have an effect on hemolysis and activation of the coagulation system. Referring to this, the HeartMate II (HMII; Thoratec Corp, Pleasanton, CA) and the HeartWare HVAD (HeartWare International Inc, Framingham, MA) were investigated. For 20 patients with LVAD support (n = 10 each), plasma coagulation, full blood count, and clinical chemistry parameters were measured. Platelet function was monitored using platelet aggregometry, platelet function analyzer-100 system ( Siemens, Marburg, Germany), vasodilator-stimulated phosphoprotein phosphorylation assay, immature platelet fraction, platelet-derived microparticles, and von Willebrand diagnostic. Acquired von Willebrand syndrome could be detected in all patients. Signs of hemolysis, as measured by lactate dehydrogenase levels (mean, 470 U/liter HMII, 250 U/liter HVAD; p < 0.001), were more pronounced in the HMII patients. In contrast, D-dimer analysis indicated a significantly higher activation of the coagulation system in HVAD patients (mean, 0.94 mg/liter HMII, 2.01 mg/liter HVAD; p < 0.01). The efficacy of anti-platelet therapy using clopidogrel was not sufficient in more than 50% of the patients. Our results support the finding that all patients with rotary blood pumps suffered from von Willebrand syndrome. In addition, a distinct footprint of effects on hemolysis and the coagulation system can be attributed to different devices. As a consequence, the individual status of the coagulation system needs to be controlled in long-term patients. © 2013 Published by International Society for the Heart and Lung Transplantation on behalf of International Society for Heart and Lung Transplantation.

Mechanical circulatory support is associated with loss of platelet receptors glycoprotein Ibα and glycoprotein VI.

PubMed

Lukito, P; Wong, A; Jing, J; Arthur, J F; Marasco, S F; Murphy, D A; Bergin, P J; Shaw, J A; Collecutt, M; Andrews, R K; Gardiner, E E; Davis, A K

2016-11-01

Essentials Relationship of acquired von Willebrand disease (VWD) and platelet dysfunction is explored. Patients with ventricular assist devices and on extracorporeal membrane oxygenation are investigated. Acquired VWD and platelet receptor shedding is demonstrated in the majority of patients. Loss of platelet adhesion receptors glycoprotein (GP) Ibα and GPVI may increase bleeding risk. Background Ventricular assist devices (VADs) and extracorporeal membrane oxygenation (ECMO) are associated with bleeding that is not fully explained by anticoagulant or antiplatelet use. Exposure of platelets to elevated shear in vitro leads to increased shedding. Objectives To investigate whether loss of platelet receptors occurs in vivo, and the relationship with acquired von Willebrand syndrome (AVWS). Methods Platelet counts, coagulation tests and von Willebrand factor (VWF) analyses were performed on samples from 21 continuous flow VAD (CF-VAD), 20 ECMO, 12 heart failure and seven aortic stenosis patients. Levels of platelet receptors were measured by flow cytometry or ELISA. Results The loss of high molecular weight VWF multimers was observed in 18 of 19 CF-VAD and 14 of 20 ECMO patients, consistent with AVWS. Platelet receptor shedding was demonstrated by elevated soluble glycoprotein (GP) VI levels in plasma and significantly reduced surface GPIbα and GPVI levels in CF-VAD and ECMO patients as compared with healthy donors. Platelet receptor levels were also significantly reduced in heart failure patients. Conclusions These data link AVWS and increased platelet receptor shedding in patients with CF-VADs or ECMO for the first time. Loss of the platelet surface receptors GPIbα and GPVI in heart failure, CF-VAD and ECMO patients may contribute to ablated platelet adhesion/activation, and limit thrombus formation under high/pathologic shear conditions. © 2016 International Society on Thrombosis and Haemostasis.

Expression of connective tissue growth factor (CTGF/CCN2) in breast cancer cells is associated with increased migration and angiogenesis.

PubMed

Chien, Wenwen; O'Kelly, James; Lu, Daning; Leiter, Amanda; Sohn, Julia; Yin, Dong; Karlan, Beth; Vadgama, Jay; Lyons, Karen M; Koeffler, H Phillip

2011-06-01

Connective tissue growth factor (CTGF/CCN2) belongs to the CCN family of matricellular proteins, comprising Cyr61, CTGF, NovH and WISP1-3. The CCN proteins contain an N-terminal signal peptide followed by four conserved domains sharing sequence similarities with the insulin-like growth factor binding proteins, von Willebrand factor type C repeat, thrombospondin type 1 repeat, and a C-terminal growth factor cysteine knot domain. To investigate the role of CCN2 in breast cancer, we transfected MCF-7 cells with full-length CCN2, and with four mutant constructs in which one of the domains had been deleted. MCF-7 cells stably expressing full-length CCN2 demonstrated reduced cell proliferation, increased migration in Boyden chamber assays and promoted angiogenesis in chorioallantoic membrane assays compared to control cells. Deletion of the C-terminal cysteine knot domain, but not of any other domain-deleted mutants, abolished activities mediated by full-length CCN2. We have dissected the role of CCN2 in breast tumorigenesis on a structural basis.

Fibroblast growth factor-10 signals development of von Brunn's nests in the exstrophic bladder

PubMed Central

Eastman, Rocky; Leaf, Elizabeth M.; Zhang, Dianzhong; True, Lawrence D.; Sweet, Robert M.; Seidel, Kristy; Siebert, Joseph R.; Grady, Richard; Mitchell, Michael E.

2010-01-01

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. PMID:20719973

Clustering of haemostatic variables and the effect of high cashew and walnut diets on these variables in metabolic syndrome patients.

PubMed

Pieters, Marlien; Oosthuizen, Welma; Jerling, Johann C; Loots, Du Toit; Mukuddem-Petersen, Janine; Hanekom, Susanna M

2005-09-01

We investigated the effect of a high walnut and cashew diet on haemostatic variables in people with the metabolic syndrome. Factor analysis was used to determine how the haemostatic variables cluster with other components of the metabolic syndrome and multiple regression to determine possible predictors. This randomized, control, parallel, controlled-feeding trial included 68 subjects who complied with the Third National Cholesterol Education Program Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol criteria. After a 3-week run-in following the control diet, subjects were divided into three groups receiving either walnuts or cashews (20 energy%) or a control diet for 8 weeks. The nut intervention had no significant effect on von Willebrand factor antigen, fibrinogen, factor VII coagulant activity, plasminogen activator inhibitor 1 activity, tissue plasminogen activator activity or thrombin activatable fibrinolysis inhibitor. Statistically, fibrinogen clustered with the body-mass-correlates and acute phase response factors, and factor VII coagulant activity clustered with high-density lipoprotein cholesterol (HDL-C). Tissue plasminogen activator activity, plasminogen activator inhibitor 1 activity and von Willebrand factor antigen clustered into a separate endothelial function factor. HDL-C and markers of obesity were the strongest predictors of the haemostatic variables. We conclude that high walnut and cashew diets did not influence haemostatic factors in this group of metabolic syndrome subjects. The HDL-C increase and weight loss may be the main focus of dietary intervention for the metabolic syndrome. Furthermore, diet composition may have only limited effects if weight loss is not achieved.

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 ...

Platelet-targeted gene therapy with human factor VIII establishes haemostasis in dogs with haemophilia A.

PubMed

Du, Lily M; Nurden, Paquita; Nurden, Alan T; Nichols, Timothy C; Bellinger, Dwight A; Jensen, Eric S; Haberichter, Sandra L; Merricks, Elizabeth; Raymer, Robin A; Fang, Juan; Koukouritaki, Sevasti B; Jacobi, Paula M; Hawkins, Troy B; Cornetta, Kenneth; Shi, Qizhen; Wilcox, David A

2013-01-01

It is essential to improve therapies for controlling excessive bleeding in patients with haemorrhagic disorders. As activated blood platelets mediate the primary response to vascular injury, we hypothesize that storage of coagulation Factor VIII within platelets may provide a locally inducible treatment to maintain haemostasis for haemophilia A. Here we show that haematopoietic stem cell gene therapy can prevent the occurrence of severe bleeding episodes in dogs with haemophilia A for at least 2.5 years after transplantation. We employ a clinically relevant strategy based on a lentiviral vector encoding the ITGA2B gene promoter, which drives platelet-specific expression of human FVIII permitting storage and release of FVIII from activated platelets. One animal receives a hybrid molecule of FVIII fused to the von Willebrand Factor propeptide-D2 domain that traffics FVIII more effectively into α-granules. The absence of inhibitory antibodies to platelet-derived FVIII indicates that this approach may have benefit in patients who reject FVIII replacement therapies. Thus, platelet FVIII may provide effective long-term control of bleeding in patients with haemophilia A.

Platelet-targeted gene therapy with human factor VIII establishes haemostasis in dogs with haemophilia A

PubMed Central

Du, Lily M.; Nurden, Paquita; Nurden, Alan T.; Nichols, Timothy C.; Bellinger, Dwight A.; Jensen, Eric S.; Haberichter, Sandra L.; Merricks, Elizabeth; Raymer, Robin A.; Fang, Juan; Koukouritaki, Sevasti B.; Jacobi, Paula M.; Hawkins, Troy B.; Cornetta, Kenneth; Shi, Qizhen; Wilcox, David A.

2013-01-01

It is essential to improve therapies for controlling excessive bleeding in patients with haemorrhagic disorders. As activated blood platelets mediate the primary response to vascular injury, we hypothesize that storage of coagulation Factor VIII within platelets may provide a locally inducible treatment to maintain haemostasis for haemophilia A. Here we show that haematopoietic stem cell gene therapy can prevent the occurrence of severe bleeding episodes in dogs with haemophilia A for at least 2.5 years after transplantation. We employ a clinically relevant strategy based on a lentiviral vector encoding the ITGA2B gene promoter, which drives platelet-specific expression of human FVIII permitting storage and release of FVIII from activated platelets. One animal receives a hybrid molecule of FVIII fused to the von Willebrand Factor propeptide-D2 domain that traffics FVIII more effectively into α-granules. The absence of inhibitory antibodies to platelet-derived FVIII indicates that this approach may have benefit in patients who reject FVIII replacement therapies. Thus, platelet FVIII may provide effective long-term control of bleeding in patients with haemophilia A. PMID:24253479

Repair of Traumatic Skeletal Muscle Injury with Bone-Marrow-Derived Mesenchymal Stem Cells Seeded on Extracellular Matrix

DTIC Science & Technology

2010-06-02

fully restored muscle fibers and blood vessels is not known; however, FIG. 4. von Willebrand factor (vWF). Masson’s Trichrome stain of sections of...dystrophic skeletal muscle is able to partially restore expression of dystrophin within the fibers .30,35,49,50 Conflict exists as to whether or not the...significantly higher number of fibers expressed in regions closer to the border with native muscle tissue indicate that engraftment of cells was not the main

Antineoplastic And Antiviral Properties Of Merocyanine 540

NASA Astrophysics Data System (ADS)

Sieber, Fritz

1989-03-01

Simultaneous exposure to the lipophilic photosensitizer, merocyanine 540, and light in the presence of serum (or certain serum components) and oxygen kills leukemia cells, lymphoma cells, neuroblastoma cells, cell-free enveloped viruses, cell-associated enveloped viruses, and virus-infected cells. The same treatment spares pluripotent hematopoietic stem cells, mature erythrocytes, factor VIII, von Willebrand factor, and probably other blood components. Merocyanine 540-mediated photosensitization is now being evaluated clinically as a means to eliminate residual tumor cells from autologous remission bone marrow grafts and preclinically as a means to inactivate pathogenic viruses in blood products.

Von Hippel-Lindau Disease

MedlinePlus

What is Von Hippel-Lindau disease (VHL)? Von Hippel-Lindau disease (VHL) is a rare disease that causes tumors and cysts to grow in your body. They ... can become cancerous. What causes Von Hippel-Lindau disease (VHL)? Von Hippel-Lindau disease (VHL) is a ...

FlnA-null megakaryocytes prematurely release large and fragile platelets that circulate poorly

PubMed Central

Jurak Begonja, Antonija; Hoffmeister, Karin M.; Hartwig, John H.

2011-01-01

Filamin A (FlnA) is a large cytoplasmic protein that crosslinks actin filaments and anchors membrane receptors and signaling intermediates. FlnAloxP PF4-Cre mice that lack FlnA in the megakaryocyte (MK) lineage have a severe macrothrombocytopenia because of accelerated platelet clearance. Macrophage ablation by injection of clodronate-encapsulated liposomes increases blood platelet counts in FlnAloxP PF4-Cre mice and reveals the desintegration of FlnA-null platelets into microvesicles, a process that occurs spontaneously during storage. FlnAloxP PF4-Cre bone marrows and spleens have a 2.5- to 5-fold increase in MK numbers, indicating increased thrombopoiesis in vivo. Analysis of platelet production in vitro reveals that FlnA-null MKs prematurely convert their cytoplasm into large CD61+ platelet-sized particles, reminiscent of the large platelets observed in vivo. FlnA stabilizes the platelet von Willebrand factor receptor, as surface expression of von Willebrand factor receptor components is normal on FlnA-null MKs but decreased on FlnA-null platelets. Further, FlnA-null platelets contain multiple GPIbα degradation products and have increased expression of the ADAM17 and MMP9 metalloproteinases. Together, the findings indicate that FlnA-null MKs prematurely release large and fragile platelets that are removed rapidly from the circulation by macrophages. PMID:21652675

Pigment epithelium derived factor inhibits the growth of human endometrial implants in nude mice and of ovarian endometriotic stromal cells in vitro.

PubMed

Sun, Yanmei; Che, Xuan; Zhu, Libo; Zhao, Mengdan; Fu, Guofang; Huang, Xiufeng; Xu, Hong; Hu, Fuqiang; Zhang, Xinmei

2012-01-01

Angiogenesis is a prerequisite for the formation and development of endometriosis. Pigment epithelium derived factor (PEDF) is a natural inhibitor of angiogenesis. We previously demonstrated a reduction of PEDF in the peritoneal fluid, serum and endometriotic lesions from women with endometriosis compared with women without endometriosis. Here, we aim to investigate the inhibitory effect of PEDF on human endometriotic cells in vivo and in vitro. We found that PEDF markedly inhibited the growth of human endometrial implants in nude mice and of ovarian endometriotic stromal cells in vitro by up-regulating PEDF expression and down-regulating vascular endothelial growth factor (VEGF) expression. Moreover, apoptotic index was significantly increased in endometriotic lesions in vivo and endometriotic stromal cells in vitro when treated with PEDF. In mice treated with PEDF, decreased microvessel density labeled by Von Willebrand factor but not by α-Smooth Muscle Actin was observed in endometriotic lesions. And it showed no increase in PEDF expression of the ovary and uterus tissues. These findings suggest that PEDF gene therapy may be a new treatment for endometriosis.

Pigment Epithelium Derived Factor Inhibits the Growth of Human Endometrial Implants in Nude Mice and of Ovarian Endometriotic Stromal Cells In Vitro

PubMed Central

Sun, Yanmei; Che, Xuan; Zhu, Libo; Zhao, Mengdan; Fu, Guofang; Huang, Xiufeng; Xu, Hong; Hu, Fuqiang; Zhang, Xinmei

2012-01-01

Angiogenesis is a prerequisite for the formation and development of endometriosis. Pigment epithelium derived factor (PEDF) is a natural inhibitor of angiogenesis. We previously demonstrated a reduction of PEDF in the peritoneal fluid, serum and endometriotic lesions from women with endometriosis compared with women without endometriosis. Here, we aim to investigate the inhibitory effect of PEDF on human endometriotic cells in vivo and in vitro. We found that PEDF markedly inhibited the growth of human endometrial implants in nude mice and of ovarian endometriotic stromal cells in vitro by up-regulating PEDF expression and down-regulating vascular endothelial growth factor (VEGF) expression. Moreover, apoptotic index was significantly increased in endometriotic lesions in vivo and endometriotic stromal cells in vitro when treated with PEDF. In mice treated with PEDF, decreased microvessel density labeled by Von Willebrand factor but not by α-Smooth Muscle Actin was observed in endometriotic lesions. And it showed no increase in PEDF expression of the ovary and uterus tissues. These findings suggest that PEDF gene therapy may be a new treatment for endometriosis. PMID:23028859

Predictive variables for mortality after acute ischemic stroke.

PubMed

Carter, Angela M; Catto, Andrew J; Mansfield, Michael W; Bamford, John M; Grant, Peter J

2007-06-01

Stroke is a major healthcare issue worldwide with an incidence comparable to coronary events, highlighting the importance of understanding risk factors for stroke and subsequent mortality. In the present study, we determined long-term (all-cause) mortality in 545 patients with ischemic stroke compared with a cohort of 330 age-matched healthy control subjects followed up for a median of 7.4 years. We assessed the effect of selected demographic, clinical, biochemical, hematologic, and hemostatic factors on mortality in patients with ischemic stroke. Stroke subtype was classified according to the Oxfordshire Community Stroke Project criteria. Patients who died 30 days or less after the acute event (n=32) were excluded from analyses because this outcome is considered to be directly attributable to the acute event. Patients with ischemic stroke were at more than 3-fold increased risk of death compared with the age-matched control cohort. In multivariate analyses, age, stroke subtype, atrial fibrillation, and previous stroke/transient ischemic attack were predictive of mortality in patients with ischemic stroke. Albumin and creatinine and the hemostatic factors von Willebrand factor and beta-thromboglobulin were also predictive of mortality in patients with ischemic stroke after accounting for demographic and clinical variables. The results indicate that subjects with acute ischemic stroke are at increased risk of all-cause mortality. Advancing age, large-vessel stroke, atrial fibrillation, and previous stroke/transient ischemic attack predict mortality; and analysis of albumin, creatinine, von Willebrand factor, and beta-thromboglobulin will aid in the identification of patients at increased risk of death after stroke.

Bleeding disorders in pregnant patients with rheumatic diseases.

PubMed

Rick, M E

1989-05-01

Although the bleeding disorders that occur in patients with rheumatic diseases are not different during pregnancy than at other times, their diagnosis and management are often different during pregnancy. In idiopathic thrombocytopenic purpura, for instance, antiplatelet antibodies may cross the placenta and cause life-threatening thrombocytopenia in the fetus while the mother is asymptomatic. Management of this disease has changed significantly in the past 5 years with the use of intravenous gammaglobulin which appears to lessen the degree of fetal as well as maternal thrombocytopenia when administered during the peripartum period. The utilization of plasmapheresis and plasma infusions for patients with thrombotic thrombocytopenic purpura has salvaged both the mother and the fetus in a disease which was fatal in more than 60 per cent of patients prior to their use. The outcome of pregnancy in this patient population has markedly improved with this treatment. The stimulus for the production of factor VIII inhibitors in the postpartum period is still not understood, but guidelines for management have changed, with the increased likelihood of decreasing the antibody and inducing tolerance with regimens including factor VIII, immunosuppressive agents and intravenous gammaglobulin in those patients who require treatment. The diagnosis of von Willebrand's disease during pregnancy is difficult because of the physiologic increase in von Willebrand factor during pregnancy; in this instance family studies may help in the diagnosis of this relatively common, autosomal dominant inherited disorder. Management now includes treatment with desmopressin as well as cryoprecipitate replacement therapy.

Industrial production of clotting factors: Challenges of expression, and choice of host cells.

PubMed

Kumar, Sampath R

2015-07-01

The development of recombinant forms of blood coagulation factors as safer alternatives to plasma derived factors marked a major advance in the treatment of common coagulation disorders. These are complex proteins, mostly enzymes or co-enzymes, involving multiple post-translational modifications, and therefore are difficult to express. This article reviews the nature of the expression challenges for the industrial production of these factors, vis-à-vis the translational and post-translational bottlenecks, as well as the choice of host cell lines for high-fidelity production. For achieving high productivities of vitamin K dependent proteins, which include factors II (prothrombin), VII, IX and X, and protein C, host cell limitation of γ-glutamyl carboxylation is a major bottleneck. Despite progress in addressing this, involvement of yet unidentified protein(s) impedes a complete cell engineering solution. Human factor VIII expresses at very low levels due to limitations at several steps in the protein secretion pathway. Protein and cell engineering, vector improvement and alternate host cells promise improvement in the productivity. Production of Von Willebrand factor is constrained by its large size, complex structure, and the need for extensive glycosylation and disulfide-bonded oligomerization. All the licensed therapeutic factors are produced in CHO, BHK or HEK293 cells. While HEK293 is a recent adoption, BHK cells appear to be disfavored. Copyright © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

β3 Integrin Haplotype Influences Gene Regulation and Plasma von Willebrand Factor Activity

PubMed Central

Payne, Katie E; Bray, Paul F; Grant, Peter J; Carter, Angela M

2008-01-01

The Leu33Pro polymorphism of the gene encoding β3 integrin (ITGB3) is associated with acute coronary syndromes and influences platelet aggregation. Three common promoter polymorphisms have also been identified. The aims of this study were to (1) investigate the influence of the ITGB3 −400C/A, −425A/C and −468G/A promoter polymorphisms on reporter gene expression and nuclear protein binding and (2) determine genotype and haplotype associations with platelet αIIbβ3 receptor density. Promoter haplotypes were introduced into an ITGB3 promoter-pGL3 construct by site directed mutagenesis and luciferase reporter gene expression analysed in HEL and HMEC-1 cells. Binding of nuclear proteins was assessed by electrophoretic mobility shift assay. The association of ITGB3 haplotype with platelet αIIbβ3 receptor density was determined in 223 subjects. Species conserved motifs were identified in the ITGB3 promoter in the vicinity of the 3 polymorphisms. The GAA, GCC, AAC, AAA and ACC constructs induced ~50% increased luciferase expression relative to the GAC construct in both cell types. Haplotype analysis including Leu33Pro indicated 5 common haplotypes; no associations between ITGB3 haplotypes and receptor density were found. However, the GCC-Pro33 haplotype was associated with significantly higher vWF activity (128.6 [112.1–145.1]%) compared with all other haplotypes (107.1 [101.2–113.0]%, p=0.02). In conclusion, the GCC-Pro33 haplotype was associated with increased vWF activity but not with platelet αIIbβ3 receptor density, which may indicate ITGB3 haplotype influences endothelial function. PMID:18045606

Basics on Genes and Genetic Disorders

MedlinePlus

... kon-druh-PLAY-zhuh, a form of dwarfism), Marfan syndrome (a connective tissue disorder), and Huntington disease (a ... this topic for: Teens Albinism Muscular Dystrophy Dwarfism Marfan Syndrome Cystic Fibrosis Hemophilia von Willebrand Disease Having a ...

Hypothyroidism in coronary heart disease and its relation to selected risk factors

PubMed Central

Mayer, Otto; Šimon, Jaroslav; Filipovský, Jan; Plášková, Markéta; Pikner, Richard

2006-01-01

Introduction Hypothyroidism (HT) has been found a predictor of cardiovascular diseases. We aimed to ascertain the prevalence of HT in patients with manifest coronary heart disease (CHD), and to establish its association with conventional risk factors. Methods 410 patients, 6–24 months after hospitalization for acute coronary syndrome, and/or revascularization, were included into the cross-sectional study. Results The prevalence of thyroid dysfunction was found in males and females as follows: overt HT, ie, thyroid stimulating hormone (TSH) > 3.65 mIU/L and free thyroxine (fT4) < 9 pmol/L and/or L-thyroxine substitution, in 2.6% and 8.4%, respectively; subclinical HT (TSH >3.65, fT4 9–23 and no substitution) in 4.3% and 15.0%, respectively. Higher prevalence of HT was found in females with hypercholesterolemia, and in males and females with concomitant positive thyroid peroxydase antibodies. Hypothyroid subjects had higher total homocysteine in both genders and von Willebrand factor in males only. Hypothyroid females had higher total and LDL cholesterol, and were more often treated for diabetes. Conclusions HT was found highly prevalent in patient with clinical coronary heart disease, mainly in females, and was associated with several cardiovascular risk factors. PMID:17323605

Wernher von Braun

NASA Image and Video Library

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.

Wernher von Braun

NASA Image and Video Library

1977-06-16

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.

Engineered living blood vessels: functional endothelia generated from human umbilical cord-derived progenitors.

PubMed

Schmidt, Dörthe; Asmis, Lars M; Odermatt, Bernhard; Kelm, Jens; Breymann, Christian; Gössi, Matthias; Genoni, Michele; Zund, Gregor; Hoerstrup, Simon P

2006-10-01

Tissue-engineered living blood vessels (TEBV) with growth capacity represent a promising new option for the repair of congenital malformations. We investigate the functionality of TEBV with endothelia generated from human umbilical cord blood-derived endothelial progenitor cells. Tissue-engineered living blood vessels were generated from human umbilical cord-derived myofibroblasts seeded on biodegradable vascular scaffolds, followed by endothelialization with differentiated cord blood-derived endothelial progenitor cells. During in vitro maturation the TEBV were exposed to physiologic conditioning in a flow bioreactor. For functional assessment, a subgroup of TEBV was stimulated with tumor necrosis factor-alpha. Control vessels endothelialized with standard vascular endothelial cells were treated in parallel. Analysis of the TEBV included histology, immunohistochemistry, biochemistry (extracellular matrix analysis, DNA), and biomechanical testing. Endothelia were analyzed by flow cytometry and immunohistochemistry (CD31, von Willebrand factor, thrombomodulin, tissue factor, endothelial nitric oxide synthase). Histologically, a three-layered tissue organization of the TEBV analogous to native vessels was observed, and biochemistry revealed the major matrix constituents (collagen, proteoglycans) of blood vessels. Biomechanical properties (Young's modulus, 2.03 +/- 0.65 MPa) showed profiles resembling those of native tissue. Endothelial progenitor cells expressed typical endothelial cell markers CD31, von Willebrand factor, and endothelial nitric oxide synthase comparable to standard vascular endothelial cells. Stimulation with tumor necrosis factor-alpha resulted in physiologic upregulation of tissue factor and downregulation of thrombomodulin expression. These results indicate that TEBV with tissue architecture and functional endothelia similar to native blood vessels can be successfully generated from human umbilical cord progenitor cells. Thus, blood

Wernher von Braun

NASA Image and Video Library

1960-01-01

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 Plarning. 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.

Growth differentiation factor-15 (GDF-15) suppresses in vitro angiogenesis through a novel interaction with connective tissue growth factor (CCN2).

PubMed

Whitson, Ramon J; Lucia, Marshall Scott; Lambert, James R

2013-06-01

Growth differentiation factor-15 (GDF-15) and the CCN family member, connective tissue growth factor (CCN2), are associated with cardiac disease, inflammation, and cancer. The precise role and signaling mechanism for these factors in normal and diseased tissues remains elusive. Here we demonstrate an interaction between GDF-15 and CCN2 using yeast two-hybrid assays and have mapped the domain of interaction to the von Willebrand factor type C domain of CCN2. Biochemical pull down assays using secreted GDF-15 and His-tagged CCN2 produced in PC-3 prostate cancer cells confirmed a direct interaction between these proteins. To investigate the functional consequences of this interaction, in vitro angiogenesis assays were performed. We demonstrate that GDF-15 blocks CCN2-mediated tube formation in human umbilical vein endothelial (HUVEC) cells. To examine the molecular mechanism whereby GDF-15 inhibits CCN2-mediated angiogenesis, activation of αV β3 integrins and focal adhesion kinase (FAK) was examined. CCN2-mediated FAK activation was inhibited by GDF-15 and was accompanied by a decrease in αV β3 integrin clustering in HUVEC cells. These results demonstrate, for the first time, a novel signaling pathway for GDF-15 through interaction with the matricellular signaling molecule CCN2. Furthermore, antagonism of CCN2 mediated angiogenesis by GDF-15 may provide insight into the functional role of GDF-15 in disease states. Copyright © 2012 Wiley Periodicals, Inc.

Origin and Evolution of the Sponge Aggregation Factor Gene Family

PubMed Central

Grice, Laura F.; Gauthier, Marie E.A.; Roper, Kathrein E.; Fernàndez-Busquets, Xavier; Degnan, Sandie M.

2017-01-01

Although discriminating self from nonself is a cardinal animal trait, metazoan allorecognition genes do not appear to be homologous. Here, we characterize the Aggregation Factor (AF) gene family, which encodes putative allorecognition factors in the demosponge Amphimedon queenslandica, and trace its evolution across 24 sponge (Porifera) species. The AF locus in Amphimedon is comprised of a cluster of five similar genes that encode Calx-beta and Von Willebrand domains and a newly defined Wreath domain, and are highly polymorphic. Further AF variance appears to be generated through individualistic patterns of RNA editing. The AF gene family varies between poriferans, with protein sequences and domains diagnostic of the AF family being present in Amphimedon and other demosponges, but absent from other sponge classes. Within the demosponges, AFs vary widely with no two species having the same AF repertoire or domain organization. The evolution of AFs suggests that their diversification occurs via high allelism, and the continual and rapid gain, loss and shuffling of domains over evolutionary time. Given the marked differences in metazoan allorecognition genes, we propose the rapid evolution of AFs in sponges provides a model for understanding the extensive diversification of self–nonself recognition systems in the animal kingdom. PMID:28104746

Wernher von Braun

NASA Image and Video Library

1970-02-24

In 1970 Marshall Space Flight Center (MSFC) Director Dr. Wernher von Braun (right) was reassigned to NASA Headquarters to serve as Deputy Associate Administrator for Plarning. Prior to his transfer, Dr. von Braun was honored for his career in Huntsville, Alabama, with the celebration of "Wernher von Braun Day." Among those participating were Alabama Governor Albert Brewer (left) and Alabama Senator John Sparkman (center). (Courtesy of Huntsville/Madison County Public library)

Risk factors for inhibitor development in severe hemophilia a.

PubMed

Garagiola, Isabella; Palla, Roberta; Peyvandi, Flora

2018-05-25

Although significant advances in hemophilia treatment have improved patient outcomes and quality of life, one of the greatest complications in severe hemophilia A is the development of anti-Factor VIII (FVIII) antibodies that inhibit FVIII activity in almost 30% of previously untreated patients (PUPs). Inhibitors make very difficult the management of patients and increase their morbidity and mortality reducing drastically their quality of life. Numerous studies have investigated the mechanisms leading to the development of FVIII inhibitors. However, the etiology of their onset is complex and not yet fully understood. Inhibitors develop from a multicausal immune response involving both genetic (unmodifiable) and environmental (modifiable) factors. F8 gene mutations are the most important genetic risk factor, with null mutations being associated with the highest risk of inhibitor development. Immune response genes (e.g. the human leukocyte antigen complex) and proteins (e.g. cytokines) were studied without any strong confirmation of their role in modulating of inhibitor development. Type of FVIII product is the most important modifiable risk factor. The plasma-derived products containing von Willebrand factor were recently suggested to determine a lower incidence of inhibitor development than recombinant products in PUPs, in the first 50 exposure days (EDs). Other environmental factors including, age at first treatment, treatment intensity and the danger signal effect (surgery, severe bleeds, vaccinations and infections) has also been postulated as an explanation for environment-related inhibitor risk. This review reports the current knowledge on genetic and environmental risk factors on inhibitor development in patients with severe hemophilia A. Copyright © 2018 Elsevier Ltd. All rights reserved.

Macro-microangiopathy and endothelial dysfunction in NIDDM patients with and without diabetic nephropathy.

PubMed

Parving, H H; Nielsen, F S; Bang, L E; Smidt, U M; Svendsen, T L; Chen, J W; Gall, M A; Rossing, P

1996-12-01

The Steno hypothesis suggests that albuminuria reflects widespread vascular damage (proliferative retinopathy and severe macroangiopathy) due to a generalized vascular (endothelial) dysfunction. We assessed this concept in NIDDM (non-insulin-dependent diabetic) patients with (13 female/ 39 male, age 60 +/- 7 years, group 1) and without (12 female /41 male, age 61 +/- 7 years, group 2) diabetic nephropathy compared to matched non-diabetic subjects (7 female/15 male, age 58 +/- 8 years, group 3). A 12-lead ECG was recorded and coded blindly using the Minnesota Rating Scale; the World Health Organization cardiovascular questionnaire was used to assess past and present evidence of myocardial infarction, angina pectoris, stroke, and peripheral vascular disease (digital systolic blood pressure determination). The degree of diabetic retinopathy was scored from fundus photography. The following variables were measured: transcapillary escape rate of albumin (initial disappearance of intravenously injected 125I-labelled human serum albumin), plasma concentrations of prorenin (radioimmunoassay) and serum concentrations of von Willebrand factor (enzyme-linked immunoadsorbent assay). Prevalence of ischaemic heart disease (ECG reading) (49/20/5)% and peripheral vascular disease as indicated by reduced systolic blood pressure on big toe (69/30/ 14)% was significantly higher in group 1 vs group 2 (p < 0.01) and in group 2 vs group 3 (p < 0.01), respectively. The prevalence and severity of retinopathy was higher in group 1 vs 2 (p < 0.01). Transcapillary escape rate of albumin (%/h) was elevated in group 1 and 2 as compared to control subjects: 7.9 (4.3-13.7); 7.4 (3.7-16.4) vs 6.0 (3.4-8.7), (p < 0.005), respectively. Plasma prorenin activity (IU/ml) was raised in group 1 and group 2 as compared to group 3: 272 (59-2405); 192 (18-813), and 85 (28-246), p < 0.001, respectively. Serum von Willebrand factor (IU/ ml) was elevated in group 1 as compared to group 2 and 3: 2.07 (0

Simulations of flow induced structural transition of the β-switch region of glycoprotein Ibα.

PubMed

Han, Mengzhi; Xu, Ji; Ren, Ying; Li, Jinghai

2016-02-01

Binding of glycoprotein Ibα to von Willebrand factor induces platelet adhesion to injured vessel walls and initiates a multistep hemostatic process. It has been hypothesized that the flow condition could induce a loop to β-sheet conformational change in the β-switch region of glycoprotein Ibα, which regulates it binding to the von Willebrand factor and facilitates the blood clot formation and wound healing. In this work, direct molecular dynamics (MD), flow MD and metadynamics, were employed to investigate the mechanisms of this flow induced conformational transition process. Specifically, the free energy landscape of the whole transition process was drawn by metadynamics with the path collective variable approach. The results reveal that without flow, the free energy landscape has two main basins, including a random loop basin stabilized by large conformational entropy and a partially folded β-sheet basin. The free energy barrier separating these two basins is relatively high and the β-switch could not fold from loop to β-sheet state spontaneously. The fully β-sheet conformations located in high free energy regions, which are also unstable and gradually unfold into partially folded β-sheet state with flow. Relatively weak flow could trigger some folding of the β-switch but could not fold it into fully β-sheet state. Under strong flow conditions, the β-switch could readily overcome the high free energy barrier and fold into fully β-sheet state. Copyright © 2015 Elsevier B.V. All rights reserved.

Angiostatin inhibits experimental liver fibrosis in mice.

PubMed

Vogten, J Mathys; Drixler, Tamas A; te Velde, Elisabeth A; Schipper, Marguerite E; van Vroonhoven, Theo J M V; Voest, Emile E; Borel Rinkes, Inne H M

2004-07-01

Liver fibrosis is a response to chronic hepatic damage, which ultimately leads to liver failure and necessitates liver transplantation. A characteristic of fibrosis is pathological vessel growth. This type of angiogenesis may contribute to the disturbance of hepatocyte perfusion dynamics and lead to aggravation of disease. We hypothesized that angiostatin can inhibit pathological vessel growth and, consequently, the development of hepatic fibrosis. Hepatic fibrosis was induced by injection of carbon tetrachloride for 5 weeks. Angiostatin mice received carbon tetrachloride for 5 weeks and angiostatin during weeks 4 and 5. After 5 weeks, immunohistochemistry for endothelial cell marker von Willebrand factor and for cell proliferation was performed. Angiogenesis was quantified by counting the number of immunopositive microvessels. Also, the relative fibrotic surface was determined using Sirius Red histostaining and computer image analysis. Immunohistochemistry revealed increased expression for von Willebrand factor in fibrotic livers. Immunopositive microvessels were localized in fibrotic areas surrounding larger vessels and in emerging fibrotic septa. Angiostatin reduced the number of immunopositive microvessels by 69% (p<0.001). In addition, angiostatin reduced the relative fibrotic area in the liver by 63+/-0.1% (p<0.001). Finally, angiostatin treatment was not associated with differences in cell proliferation. Angiostatin inhibits the development of pathological angiogenesis and liver fibrosis in mice. These results warrant further evaluation of angiostatin as an antifibrotic agent, potentially contributing to the deferment of liver transplantation and reduced recurrence of fibrotic disease in the transplanted liver.

Disorders of Platelet Function

PubMed Central

Huebsch, Lothar B.; Harker, Laurence A.

1981-01-01

Platelets play an important role in hemostasis, and alterations in platelet function may be the cause of abnormal bleeding in a wide variety of congenital and acquired clinical disorders. Platelet dysfunction may be classified as disorders of (1) substrate connective tissue, (2) adhesion, (3) aggregation and (4) platelet-release reaction. The congenital defects of platelet function, although uncommon, have provided important insights into platelet physiology and pathophysiology and, as a group, are less common, better characterized and more readily classified than the acquired defects. The severity of bleeding resulting from platelet dysfunction varies greatly and is substantially increased when another defect of hemostasis coexists. A disorder of platelet function is suspected on the basis of the history and physical examination and is confirmed by the finding of a prolonged bleeding time in the presence of an adequate number of platelets. A specific diagnosis often requires measurements of the factor VIII and von Willebrand factor complex and other tests of platelet function. Some of these tests may be available only in specialized laboratories. Therapy for bleeding episodes resulting from platelet dysfunction is directed at (1) removing or treating the underlying cause of the platelet disorder; (2) replacing the missing plasma cofactors needed to support normal platelet function (such as by the transfusion of cryoprecipitate in patients with von Willebrand disease, and (3) transfusing functional platelets in the form of platelet concentrates in patients with disorders of intrinsic platelet dysfunction. ImagesFigure 1.Figure 2.Figure 3. PMID:7013276

Antihuman factor VIII C2 domain antibodies in hemophilia A mice recognize a functionally complex continuous spectrum of epitopes dominated by inhibitors of factor VIII activation

PubMed Central

Meeks, Shannon L.; Healey, John F.; Parker, Ernest T.; Barrow, Rachel T.

2007-01-01

The diversity of factor VIII (fVIII) C2 domain antibody epitopes was investigated by competition enzyme-linked immunosorbent assay (ELISA) using a panel of 56 antibodies. The overlap patterns produced 5 groups of monoclonal antibodies (MAbs), designated A, AB, B, BC, and C, and yielded a set of 18 distinct epitopes. Group-specific loss of antigenicity was associated with mutations at the Met2199/Phe2200 phospholipid binding β-hairpin (group AB MAbs) and at Lys2227 (group BC MAbs), which allowed orientation of the epitope structure as a continuum that covers one face of the C2 β-sandwich. MAbs from groups A, AB, and B inhibit the binding of fVIIIa to phospholipid membranes. Group BC was the most common group and displayed the highest specific fVIII inhibitor activities. MAbs in this group are type II inhibitors that inhibit the activation of fVIII by either thrombin or factor Xa and poorly inhibit the binding of fVIII to phospholipid membranes or von Willebrand factor (VWF). Group BC MAbs are epitopically and mechanistically distinct from the extensively studied group C MAb, ESH8. These results reveal the structural and functional complexity of the anti-C2 domain antibody response and indicate that interference with fVIII activation is a major attribute of the inhibitor landscape. PMID:17848617

Wernher von Braun

NASA Image and Video Library

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.

Risk Factors for and Management of MPN-Associated Bleeding and Thrombosis.

PubMed

Martin, Karlyn

2017-10-01

The Philadelphia chromosome-negative myeloproliferative neoplasms (MPN) are characterized by both thrombotic and bleeding complications. The purpose of this review is to describe the risk factors associated with bleeding and thrombosis in MPN, as well as to review prevention strategies and management of these complications. Well-described risk factors for thrombotic complications include older age and history of prior thrombosis, along with traditional cardiovascular and venous thromboembolic risk factors. More recently, JAK2 V617F mutation has been found to carry an increased risk of thrombotic complications, whereas CALR has a lower risk than JAK2 mutation. Factors associated with an increased risk of bleeding in MPN include a prior history of bleeding, acquired von Willebrand syndrome, and primary myelofibrosis. Recent findings suggest that thrombocytosis carries a higher risk of bleeding than thrombosis in MPN, and aspirin may exacerbate this risk of bleeding, particularly in CALR-mutated ET. Much of the management of MPN focuses on predicting risk of bleeding and thrombosis and initiating prophylaxis to prevent complications in those at high risk of thrombosis. Emerging evidence suggests that sub-populations may have bleeding risk that outweighs thrombotic risk, particularly in setting of antiplatelet therapy. Future work is needed to better characterize this balance. At present, a thorough assessment of the risks of bleeding and thrombosis should be undertaken for each patient, and herein, we review risk factors for and management of these complications.

Integrated fluorescence correlation spectroscopy device for point-of-care clinical applications

PubMed Central

Olson, Eben; Torres, Richard; Levene, Michael J.

2013-01-01

We describe an optical system which reduces the cost and complexity of fluorescence correlation spectroscopy (FCS), intended to increase the suitability of the technique for clinical use. Integration of the focusing optics and sample chamber into a plastic component produces a design which is simple to align and operate. We validate the system by measurements on fluorescent dye, and compare the results to a commercial instrument. In addition, we demonstrate its application to measurements of concentration and multimerization of the clinically relevant protein von Willebrand factor (vWF) in human plasma. PMID:23847733

Data for a direct fibrinolytic metalloproteinase, barnettlysin-I from Bothrops barnetti (barnett,s pitviper) snake venom with anti-thrombotic effect

PubMed Central

Sanchez, Eladio Flores; Richardson, Michael; Gremski, Luiza Helena; Veiga, Silvio Sanches; Yarleque, Armando; Niland, Stephan; Lima, Augusto Martins; Estevao-Costa, Maria Inácia; Eble, Johannes Andreas

2016-01-01

Initial association of platelets after vascular injury is mediated by glycoprotein (GP)Ib-IX-V binding to von Willebrand factor (vWf) immobilized on exposed collagens and eventually leads to thrombus formation. This article provides data about a new P-I class snake venom metalloproteinase (SVMP), barnettlysin-I (Bar-I), purified from the venom of Bothrops barnetti. This Data in Brief manuscript complements the main research article by providing additional data of the biochemical characterization of Bar-I 10.1016/j.bbagen.2015.12.021[1]. PMID:27222863

Blood coagulation abnormalities in multibacillary leprosy patients.

PubMed

Silva, Débora Santos da; Teixeira, Lisandra Antonia Castro; Beghini, Daniela Gois; Ferreira, André Teixeira da Silva; Pinho, Márcia de Berredo Moreira; Rosa, Patricia Sammarco; Ribeiro, Marli Rambaldi; Freire, Monica Di Calafiori; Hacker, Mariana Andrea; Nery, José Augusto da Costa; Pessolani, Maria Cristina Vidal; Tovar, Ana Maria Freire; Sarno, Euzenir Nunes; Perales, Jonas; Bozza, Fernando Augusto; Esquenazi, Danuza; Monteiro, Robson Queiroz; Lara, Flavio Alves

2018-03-01

Leprosy is a chronic dermato-neurological disease caused by Mycobacterium leprae infection. In 2016, more than 200,000 new cases of leprosy were detected around the world, representing the most frequent cause of infectious irreversible deformities and disabilities. In the present work, we demonstrate a consistent procoagulant profile on 40 reactional and non-reactional multibacillary leprosy patients. A retrospective analysis in search of signs of coagulation abnormalities among 638 leprosy patients identified 35 leprosy patients (5.48%) which displayed a characteristic lipid-like clot formed between blood clot and serum during serum harvesting, herein named 'leprosum clot'. Most of these patients (n = 16, 45.7%) belonged to the lepromatous leprosy pole of the disease. In addition, formation of the leprosum clot was directly correlated with increased plasma levels of soluble tissue factor and von Willebrand factor. High performance thin layer chromatography demonstrated a high content of neutral lipids in the leprosum clot, and proteomic analysis demonstrated that the leprosum clot presented in these patients is highly enriched in fibrin. Remarkably, differential 2D-proteomics analysis between leprosum clots and control clots identified two proteins present only in leprosy patients clots: complement component 3 and 4 and inter-alpha-trypsin inhibitor family heavy chain-related protein (IHRP). In agreement with those observations we demonstrated that M. leprae induces hepatocytes release of IHRP in vitro. We demonstrated that leprosy MB patients develop a procoagulant status due to high levels of plasmatic fibrinogen, anti-cardiolipin antibodies, von Willebrand factor and soluble tissue factor. We propose that some of these components, fibrinogen for example, presents potential as predictive biomarkers of leprosy reactions, generating tools for earlier diagnosis and treatment of these events.

Platelet binding sites for factor VIII in relation to fibrin and phosphatidylserine

PubMed Central

Novakovic, Valerie A.; Shi, Jialan; Rasmussen, Jan; Pipe, Steven W.

2015-01-01

Thrombin-stimulated platelets expose very little phosphatidylserine (PS) but express binding sites for factor VIII (fVIII), casting doubt on the role of exposed PS as the determinant of binding sites. We previously reported that fVIII binding sites are increased three- to sixfold when soluble fibrin (SF) binds the αIIbβ3 integrin. This study focuses on the hypothesis that platelet-bound SF is the major source of fVIII binding sites. Less than 10% of fVIII was displaced from thrombin-stimulated platelets by lactadherin, a PS-binding protein, and an fVIII mutant defective in PS-dependent binding retained platelet affinity. Therefore, PS is not the determinant of most binding sites. FVIII bound immobilized SF and paralleled platelet binding in affinity, dependence on separation from von Willebrand factor, and mediation by the C2 domain. SF also enhanced activity of fVIII in the factor Xase complex by two- to fourfold. Monoclonal antibody (mAb) ESH8, against the fVIII C2 domain, inhibited binding of fVIII to SF and platelets but not to PS-containing vesicles. Similarly, mAb ESH4 against the C2 domain, inhibited >90% of platelet-dependent fVIII activity vs 35% of vesicle-supported activity. These results imply that platelet-bound SF is a component of functional fVIII binding sites. PMID:26162408

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.

Association Between Changes in Air Pollution Levels During the Beijing Olympics and Biomarkers of Inflammation and Thrombosis in Healthy Young Adults

PubMed Central

Rich, David Q.; Kipen, Howard M.; Huang, Wei; Wang, Guangfa; Wang, Yuedan; Zhu, Ping; Ohman-Strickland, Pamela; Hu, Min; Philipp, Claire; Diehl, Scott R.; Lu, Shou-En; Tong, Jian; Gong, Jicheng; Thomas, Duncan; Zhu, Tong; Zhang, Junfeng (Jim)

2014-01-01

Context Air pollution is a risk factor for cardiovascular diseases (CVD), but the underlying biological mechanisms are not well understood. Objective To determine whether markers related to CVD pathophysiological pathways (biomarkers for systemic inflammation and thrombosis, heart rate, and blood pressure) are sensitive to changes in air pollution. Design, Setting, and Participants Using a quasi-experimental opportunity offered by greatly restricted air pollution emissions during the Beijing Olympics, we measured pollutants daily and the outcomes listed below in 125 healthy young adults before, during, and after the 2008 Olympics (June 2-October 30). We used linear mixed-effects models to estimate the improvement in outcome levels during the Olympics and the anticipated reversal of outcome levels after pollution controls ended to determine whether changes in outcome levels were associated with changes in pollutant concentrations. Main Outcome Measures C-reactive protein (CRP), fibrinogen, von Willebrand factor, soluble CD40 ligand (sCD40L), soluble P-selectin (sCD62P) concentrations; white blood cell count (WBC); heart rate; and blood pressure. Results Concentrations of particulate and gaseous pollutants decreased substantially (−13% to −60%) from the pre-Olympic period to the during-Olympic period. Using 2-sided tests conducted at the .003 level, we observed statistically significant improvements in sCD62P levels by −34.0% (95% CI, −38.4% to −29.2%; P<.001) from a pre-Olympic mean of 6.29 ng/mL to a during-Olympic mean of 4.16 ng/mL and von Willebrand factor by −13.1% (95% CI, −18.6% to −7.5%; P<.001) from 106.4% to 92.6%. After adjustments for multiple comparisons, changes in the other outcomes were not statistically significant. In the post-Olympic period when pollutant concentrations increased, most outcomes approximated pre-Olympic levels, but only sCD62P and systolic blood pressure were significantly worsened from the during-Olympic period

Occult cancer detection in patients with hemostatic disorder and venous thromboembolism.

PubMed

Husseinzadeh, Holleh; Carrier, Marc

2018-03-01

There are physiologic ties between Von Willebrand Factor (VWF) and circulating tumor cells. VWF appears to play a role in tumor biology, but it is unclear whether cancer behavior differs in Von Willebrand Disease. In patients presenting with venous thromboembolism (VTE), occult cancer is frequently considered as an underlying cause. The prevalence of occult cancer after provoked VTE is low (3%); therefore, cancer screening in these patients is not routinely recommended. In those with unprovoked VTE, occult cancer is more prevalent, estimated between 4 and 10%. Due to this elevated risk, occult cancer screening is recommended in this population. Multiple studies have investigated whether a "limited" approach (including history and physical exam, basic labs, and chest X-ray) versus "extensive" approach (addition of advanced imaging, such as computer tomography) is more effective. Current data fails to demonstrate extensive screening strategies diagnose more occult cancer, miss fewer cancers during follow up, or improve cancer-related mortality. Furthermore, many patients may be needlessly exposed to unnecessary diagnostic procedures with their associated complications and costs, as well as significant anxiety. Therefore, the decision to perform additional testing should be made on a case-by-case basis. Additional studies are needed to identify subgroups of patients with unprovoked VTE at highest risk for occult cancer. Copyright © 2017 Elsevier Ltd. All rights reserved.

Fitness and quality of life in children with haemophilia.

PubMed

Broderick, C R; Herbert, R D; Latimer, J; Curtin, J A

2010-01-01

Prior to the introduction of prophylactic clotting factor, children with haemophilia were discouraged from physical activity due to the risk of bleeds. Reports of children with haemophilia having lower levels of fitness and strength than their healthy peers were therefore well accepted. This study aimed to establish whether these deficits continued, and specifically, whether Australian boys with haemophilia and von Willebrand disorder had lower strength and aerobic capacity than their peers, despite widespread use of prophylaxis. Forty-four boys aged 6.1-17.0 years (mean 10.9, SD 3.2) with haemophilia A and B and von Willebrand disorder participated in the study. Fitness, strength and body mass index (BMI) measures were compared with age- and gender-matched data from a representative cohort of school children. Quality of Life was measured using the Haemo-QoL to obtain baseline measures in an Australian population. There were no statistically significant or clinically important differences in aerobic fitness or BMI between the boys with haemophilia and controls in any age category. Boys with haemophilia in Years 4, 6 and 10 had greater strength than their peers. Australian boys with bleeding disorders do not have impaired aerobic capacity or strength compared with their peers. Quality of life in Australian boys with haemophilia is comparable to their European counterparts.

Adhesive properties of the isolated amino-terminal domain of platelet glycoprotein Ibα in a flow field

PubMed Central

Marchese, Patrizia; Saldívar, Enrique; Ware, Jerry; Ruggeri, Zaverio M.

1999-01-01

We have examined the interaction between the amino-terminal domain of platelet glycoprotein (GP) Ibα and immobilized von Willebrand Factor (vWF) under flow conditions in the absence of other components of the GP Ib–IX–V complex. Latex beads were coated with a recombinant fragment containing GP Ibα residues 1–302, either with normal sequence or with the single G233V substitution that causes enhanced affinity for plasma vWF in platelet-type pseudo-von-Willebrand disease. Beads coated with native fragment adhered to vWF in a manner comparable to platelets, showing surface translocation that reflected the transient nature of the bonds formed. Thus, the GP Ibα extracellular domain is necessary and sufficient for interacting with vWF under high shear stress. Beads coated with the mutated fragment became tethered to vWF in greater number and had lower velocity of translocation than beads coated with the normal counterpart, suggesting that the G233V mutation lowers the rate of bond dissociation. Our findings define an approach for studying the biomechanical properties of the GP Ibα–vWF bond and suggest that this interaction is tightly regulated to allow rapid binding at sites of vascular injury, while permitting the concurrent presence of receptor and ligand in the circulation. PMID:10393908

Wernher von Braun

NASA Image and Video Library

1959-01-01

Five of the seven original astronauts are seen with Dr. von Braun inspecting the Mercury-Redstone hardware in the Fabrication Laboratory of Army Ballistic Missile Agency (ABMA) in 1959. Left to right: Astronauts Walter Schirra, Alan Shepard, John Glenn, Scott Carpenter, Gordon Cooper, and Dr. von Braun.

Animal Models of Hemophilia and Related Bleeding Disorders

PubMed Central

Lozier, Jay N.; Nichols, Timothy C.

2013-01-01

Animal models of hemophilia and related diseases are important for development of novel treatments and to understand the pathophysiology of bleeding disorders in humans. Testing in animals with the equivalent human disorder provides informed estimates of doses and measures of efficacy, which aids in design of human trials. Many models of hemophilia A, hemophilia B, and von Willebrand disease have been developed from animals with spontaneous mutations (hemophilia A dogs, rats, sheep; hemophilia B dogs; and von Willebrand disease pigs and dogs), or by targeted gene disruption in mice to create hemophilia A, B, or VWD models. Animal models have been used to generate new insights into the pathophysiology of each bleeding disorder and also to perform pre-clinical assessments of standard protein replacement therapies as well as novel gene transfer technology. Both the differences between species and differences in underlying causative mutations must be considered in choosing the best animal for a specific scientific study PMID:23956467

Hepatocellular hypoxia-induced vascular endothelial growth factor expression and angiogenesis in experimental biliary cirrhosis.

PubMed

Rosmorduc, O; Wendum, D; Corpechot, C; Galy, B; Sebbagh, N; Raleigh, J; Housset, C; Poupon, R

1999-10-01

We tested the potential role of vascular endothelial growth factor (VEGF) and of fibroblast growth factor-2 (FGF-2) in the angiogenesis associated with experimental liver fibrogenesis induced by common bile duct ligation in Sprague-Dawley rats. In normal rats, VEGF and FGF-2 immunoreactivities were restricted to less than 3% of hepatocytes. One week after bile duct ligation, hypoxia was demonstrated by the immunodetection of pimonidazole adducts unevenly distributed throughout the lobule. After 2 weeks, hypoxia and VEGF expression were detected in >95% of hepatocytes and coexisted with an increase in periportal vascular endothelial cell proliferation, as ascertained by Ki67 immunolabeling. Subsequently, at 3 weeks the density of von Willebrand-labeled vascular section in fibrotic areas significantly increased. Semiquantitative reverse transcription polymerase chain reaction showed that VEGF(120) and VEGF(164) transcripts, that correspond to secreted isoforms, increased within 2 weeks, while VEGF(188) transcripts remained unchanged. FGF-2 mainly consisting of a 22-kd isoform, according to Western blot, was identified by immunohistochemistry in 49% and 100% of hepatocytes at 3 and 7 weeks, respectively. Our data provide evidence that in biliary-type liver fibrogenesis, angiogenesis is stimulated primarily by VEGF in response to hepatocellular hypoxia while FGF-2 likely contributes to the maintenance of angiogenesis at later stages.

Origin and Evolution of the Sponge Aggregation Factor Gene Family.

PubMed

Grice, Laura F; Gauthier, Marie E A; Roper, Kathrein E; Fernàndez-Busquets, Xavier; Degnan, Sandie M; Degnan, Bernard M

2017-05-01

Although discriminating self from nonself is a cardinal animal trait, metazoan allorecognition genes do not appear to be homologous. Here, we characterize the Aggregation Factor (AF) gene family, which encodes putative allorecognition factors in the demosponge Amphimedon queenslandica, and trace its evolution across 24 sponge (Porifera) species. The AF locus in Amphimedon is comprised of a cluster of five similar genes that encode Calx-beta and Von Willebrand domains and a newly defined Wreath domain, and are highly polymorphic. Further AF variance appears to be generated through individualistic patterns of RNA editing. The AF gene family varies between poriferans, with protein sequences and domains diagnostic of the AF family being present in Amphimedon and other demosponges, but absent from other sponge classes. Within the demosponges, AFs vary widely with no two species having the same AF repertoire or domain organization. The evolution of AFs suggests that their diversification occurs via high allelism, and the continual and rapid gain, loss and shuffling of domains over evolutionary time. Given the marked differences in metazoan allorecognition genes, we propose the rapid evolution of AFs in sponges provides a model for understanding the extensive diversification of self-nonself recognition systems in the animal kingdom. © The Author 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

Ethnic-specific relationships between haemostatic and oxidative stress markers in black and white South Africans: The SABPA study.

PubMed

Lammertyn, Leandi; Mels, Catharina M C; Pieters, Marlien; Schutte, Aletta E; Schutte, Rudolph

2015-01-01

Haemostatic- and oxidative stress markers are associated with increased cardiovascular risk. In the black population, evidence exists that both an imbalance in the haemostatic system and oxidative stress link with the development of hypertension. However, it is unclear whether these two risk components function independently or are related, specifically in the black population, who is known to have a high prevalence of stroke. We aimed to investigate associations between the haemostatic system and oxidative stress in black and white South Africans. We performed a cross-sectional study including 181 black (mean age, 44; 51.4% women) and 209 white (mean age, 45; 51.7% women) teachers. Several markers of the haemostatic- (von Willebrand factor, fibrinogen, plasminogen activator inhibitor-1, d-dimer and clot lysis time) and oxidant-antioxidant (serum peroxides, total glutathione, glutathione peroxidase- and glutathione reductase activities) systems were measured. Along with a worsened cardiovascular profile, the black group had higher haemostatic-, inflammation- and oxidative stress markers as well as decreased glutathione peroxidase activity. In multiple regression analyses, fibrinogen was positively associated with serum peroxides (p < 0.001) in both ethnic groups. In the black population, we found negative associations of von Willebrand factor and clot lysis time with glutathione peroxidase activity (p ≤ 0.008), while a positive association existed between clot lysis time and serum peroxides (p = 0.011) in the white population. We conclude that in the black population, decreased GPx activity accompanies an altered haemostatic profile, while in the white population associations may suggest that serum peroxides impair fibrin clot lysis.

Inattentional blindness and the von Restorff effect.

PubMed

Schmidt, Stephen R; Schmidt, Constance R

2015-02-01

Sometimes we fail to notice distinctive or unusual items (inattentional blindness), while other times we remember distinctive items more than expected items (the von Restorff effect). A three-factor framework is presented and tested in two experiments in an attempt to reconcile these seemingly contradictory phenomena. Memory for different types of unexpected stimuli was tested after an easy or difficult Stroop color-naming task. Highly arousing taboo words were well remembered even when the difficult Stroop task limited attentional resources. However, a conceptual isolation effect was only observed when the nature of the category change was highlighted by the Stroop task, the Stroop task was easy, and/or the isolated targets enjoyed a retrieval advantage relative to comparison targets. As proposed in the three-factor framework, the arousing qualities of the stimuli, the attentional demands of the primary task, and the relevance of isolated features at encoding and retrieval combine to produce inattentional blindness and the von Restorff effect.

Haemangiosarcoma in the uterine remnant of a spayed female dog.

PubMed

Wenzlow, N; Tivers, M S; Selmic, L E; Scurrell, E J; Baines, S J; Smith, K C

2009-09-01

A 11-year-old, female, spayed greyhound was presented with a haemorrhagic discharge from the vulva. Clinical examination, vaginoscopy and a computed tomography scan showed an irregular egg-sized mass in the region of the cervix and uterine stump. An endoscopic grab biopsy (incisional) suggested a malignant mesenchymal tumour. Following this, surgical excision of the cranial vagina, cervix and the uterine remnant was performed. The final diagnosis of haemangiosarcoma was based on histological examination of the larger excisional biopsy specimen and was confirmed by positive immunolabelling of the neoplastic endothelial cells for the von Willebrand factor.

School Absences and School Achievements in Children with Congenital Coagulation Disorders.

ERIC Educational Resources Information Center

Kvist, S. Beatrice M.

1988-01-01

Ten Finnish children (aged 7-15 years) suffering from hemophilia or von Willebrand's disease were compared with 20 healthy schoolmates with reference to scholastic achievement and school absences. It appears that despite a greater number of absences, the children affected by the disease were doing relatively well in school. (TJH)

Titanisierung von Implantatoberflächen

NASA Astrophysics Data System (ADS)

Zimmermann, Hanngörg; Heinlein, Markus; Guldner, Norbert W.

Titan gilt seit Jahrzehnten als einer der wichtigsten Implantatwerkstoffe in der Medizin. Neben den guten mechanischen Eigenschaften (Leichtigkeit, hohe Festigkeit etc.), besitzen Titanimplantate vor allem eine hervorragende Körperverträglichkeit, so dass die Implantate optimal in den humanen Organismus integriert werden [1]. Ist jedoch aufgrund der Anforderungen an das Implantat eine hohe Flexibilität und/ oder Elastizität gefragt, so scheidet der Werkstoff Titan aufgrund seiner spröden und unflexiblen Materialeigenschaften aus. Die Folge ist der Einsatz von Implantatmaterialien, sowohl künstlichen als auch biologischen Ursprungs, welche nicht selten eine unzureichende Biokompatibilität aufweisen und somit zu Fremdköper- und immunologischen Reaktionen und Einkapselung des Implantates führen können. Die Erhöhung der Körperverträglichkeit, eine Adaption an das biologische Umfeld und eine hohe Biokompatibilität sind demzufolge die wichtigsten Eigenschaften bei der bedarfsgerechten Herstellung von Implantaten und Implantatoberflächen. Zur Gestaltung von innovativen, biokompatiblen Oberflächen stehen unterschiedliche technische Lösungsansätze zur Verfügung. Zum einen besteht die Möglichkeit, geeignete Oberflächeneigenschaften aus dem Grundmaterial selbst zu optimieren. Dies geschieht unter anderem durch Modifikation der Werkstoffoberflächen in Form von Texturierungen und Oberflächenrauhigkeiten. Zum anderen können die Oberflächeneigenschaften unabhängig von denen des Trägermaterials gestaltet werden. Durch Funktionalisierung der Oberflächen mit geeigneten Beschichtungen oder der Zugabe von Medikamenten (Drug Eluting) werden die Kunststoffimplantate dahingehend verändert, dass eine Steigerung der Körperakzeptanz erreicht wird. Die Titanbeschichtung von Implantatoberflächen kombiniert die positiven Materialeigenschaften von Titan und Polymer.

Wernher von Braun

NASA Image and Video Library

1968-01-22

Dr. Wernher Von Braun, stands in front of a Saturn IB Launch Vehicle at Kennedy Space Center (KSC). Dr. Von Braun was Marshall's first Center Director (1960-1970). Under his leadership Marshall was responsible for the development of the Saturn rockets, the Skylab project and getting the United States into Space and landing on the moon with the Apollo missions.

Developmentally arrested structures preceding cerebellar tumors in von Hippel–Lindau disease

PubMed Central

Shively, Sharon B; Falke, Eric A; Li, Jie; Tran, Maxine G B; Thompson, Eli R; Maxwell, Patrick H; Roessler, Erich; Oldfield, Edward H; Lonser, Russell R; Vortmeyer, Alexander O

2011-01-01

There is increasing evidence that suggests that knockout of tumor-suppressor gene function causes developmental arrest and protraction of cellular differentiation. In the peripheral nervous system of patients with the tumor-suppressor gene disorder, von Hippel–Lindau disease, we have demonstrated developmentally arrested structural elements composed of hemangioblast progenitor cells. Some developmentally arrested structural elements progress to a frank tumor, hemangioblastoma. However, in von Hippel–Lindau disease, hemangioblastomas are frequently observed in the cerebellum, suggesting an origin in the central nervous system. We performed a structural and topographic analysis of cerebellar tissues obtained from von Hippel–Lindau disease patients to identify and characterize developmentally arrested structural elements in the central nervous system. We examined the entire cerebella of five tumor-free von Hippel–Lindau disease patients and of three non-von Hippel–Lindau disease controls. In all, 9 cerebellar developmentally arrested structural elements were detected and topographically mapped in 385 blocks of von Hippel–Lindau disease cerebella. No developmentally arrested structural elements were seen in 214 blocks from control cerebella. Developmentally arrested structural elements are composed of poorly differentiated cells that express hypoxia-inducible factor (HIF)2α, but not HIF1α or brachyury, and preferentially involve the molecular layer of the dorsum cerebelli. For the first time, we identify and characterize developmentally arrested structural elements in the central nervous system of von Hippel–Lindau patients. We provide evidence that developmentally arrested structural elements in the cerebellum are composed of developmentally arrested hemangioblast progenitor cells in the molecular layer of the dorsum cerebelli. PMID:21499240

Wernher von Braun

NASA Image and Video Library

1970-02-24

Dr. von Braun was honored with a series of farewell events and ceremonies prior to his reassignment to NASA Headquarters in Washington, D.C. Alabama Governor Brewer greets Dr. von Braun following his speech at the front of the Madison County Courthouse in Huntsville, Alabama on February 24, 1970. Behind are Madison County Commissioner James Record, Huntsville Mayor Joe Davis, and U.S. Senator Sparkman.

Wernher von Braun

NASA Image and Video Library

1969-07-24

Apollo 11 splashdown celebration in Huntsville, Alabama, on July 24, 1969. Huntsville Alabama is the home of the Marshall Space Flight Center which developed the Saturn vehicles under the direction of Dr. von Braun. The photo shows Dr. von Braun speaking to the crowd at the Madison County Courthouse as Mayor Joe Davis, Madison County Commissioner James Record and City Council President Ken Johnson look on.

Wernher von Braun

NASA Image and Video Library

1969-07-24

Dr. von Braun is carried aloft on the shoulders of Huntsville city officials during the Apollo 11 celebration in Huntsville, Alabama, on July 24, 1969. Huntsville, Alabama is the home of the Marshall Space Flight Center which developed the Saturn vehicles under the direction of Dr. von Braun. The Apollo 11 lifted off in July and made the first marned lunar landing on the Moon.

Anticoagulatory and antiinflammatory effects of astaxanthin in diabetic rats.

PubMed

Chan, Kung-Chi; Pen, Pei-Jain; Yin, Mei-Chin

2012-02-01

Astaxanthin at 0.01 or 0.05% of the diet was supplied to diabetic rats for 12 wk. Astaxanthin intake significantly increased its deposit in plasma, and retained glutathione content, reduced the production of reactive oxygen species, interleukin-6, tumor necrosis factor-α, and monocyte chemoattractant protein-1 in blood and kidney of diabetic rats (P < 0.05). Astaxanthin treatments also significantly decreased plasma levels of C-reactive protein and von Willebrand factor in diabetic rats (P < 0.05). Astaxanthin intake at 0.05% significantly diminished plasminogen activator inhibitor-1 and factor VII activities, enhanced antithrombin-III and protein C activities in circulation (P < 0.05). These results support that astaxanthin could attenuate diabetes associated coagulatory, oxidative, and inflammatory stress. © 2012 Institute of Food Technologists®

Factor VIII inhibitor in a patient with mild haemophilia A and an Asn618-->Ser mutation responsive to immune tolerance induction and cyclophosphamide.

PubMed

Vlot, André J; Wittebol, Shulamiet; Strengers, Paul F W; Turenhout, Ellen A M; Voorberg, Jan; van den Berg, H Marijke; Mauser-Bunschoten, Eveline P

2002-04-01

We describe a patient with mild haemophilia A (original value of factor VIII activity 0.30 U/ml) who developed an inhibitor (36.1 Bethesda U/ml) which cross-reacted with his endogenous factor VIII. This caused a decline in basal factor VIII level (< 0.01 U/ml) and severe haemorrhagic events. Treatment to induce immune tolerance was started with factor VIII/von Willebrand factor (VWF) concentrates, but inhibitor levels increased progressively and the patient suffered serious bleeding. Cyclophosphamide was administered and, after 8 months treatment, factor VIII levels increased to 0.20 U/ml and the inhibitor could no longer be detected. Screening of his factor VIII gene revealed a missense mutation in exon 13 that predicts substitution of Asn618-->Ser in the A2 domain of factor VIII. Immunoprecipitation analysis showed that the antibodies present in the patient's plasma reacted with metabolically labelled A2 domain and, to a lesser extent, with factor VIII light chain. Inhibitory antibodies were completely neutralized by recombinant A2 domain, whereas no neutralization was observed after the addition of factor VIII light chain (A3-C1-C2) and C2 domain. More detailed analysis showed that the majority of inhibitory antibodies were directed against residues Arg484-Ile508, a previously identified binding site for factor VIII inhibitors. Our findings suggest that immune tolerance therapy and cyclophosphamide were successful in eradicating inhibitory antibodies against a common epitope on factor VIII.

Vacuum-assisted closure therapy increases local interleukin-8 and vascular endothelial growth factor levels in traumatic wounds.

PubMed

Labler, Ludwig; Rancan, Mario; Mica, Ladislav; Härter, Luc; Mihic-Probst, Daniela; Keel, Marius

2009-03-01

Clinical observations are suggesting accelerated granulation tissue formation in traumatic wounds treated with vacuum-assisted closure (VAC). Aim of this study was to determine the impact of VAC therapy versus alternative Epigard application on local inflammation and neovascularization in traumatic soft tissue wounds. Thirty-two patients with traumatic wounds requiring temporary coverage (VAC n = 16; Epigard n = 16) were included. At each change of dressing, samples of wound fluid and serum were collected (n = 80). The cytokines interleukin (IL)-6, IL-8, vascular endothelial growth factor (VEGF), and fibroblast growth factor-2 were measured by ELISA. Wound biopsies were examined histologically for inflammatory cells and degree of neovascularization present. All cytokines were found to be elevated in wound fluids during both VAC and Epigard treatment, whereas serum concentrations were negligible or not detectable. In wound fluids, significantly higher IL-8 (p < 0.001) and VEGF (p < 0.05) levels were detected during VAC therapy. Furthermore, histologic examination revealed increased neovascularization (p < 0.05) illustrated by CD31 and von Willebrand factor immunohistochemistry in wound biopsies of VAC treatment. In addition, there was an accumulation of neutrophils as well as an augmented expression of VEGF (p < 0.005) in VAC wound biopsies. This study suggests that VAC therapy of traumatic wounds leads to increased local IL-8 and VEGF concentrations, which may trigger accumulation of neutrophils and angiogenesis and thus, accelerate neovascularization.

Von Bertalanffy's dynamics under a polynomial correction: Allee effect and big bang bifurcation

NASA Astrophysics Data System (ADS)

Leonel Rocha, J.; Taha, A. K.; Fournier-Prunaret, D.

2016-02-01

In this work we consider new one-dimensional populational discrete dynamical systems in which the growth of the population is described by a family of von Bertalanffy's functions, as a dynamical approach to von Bertalanffy's growth equation. The purpose of introducing Allee effect in those models is satisfied under a correction factor of polynomial type. We study classes of von Bertalanffy's functions with different types of Allee effect: strong and weak Allee's functions. Dependent on the variation of four parameters, von Bertalanffy's functions also includes another class of important functions: functions with no Allee effect. The complex bifurcation structures of these von Bertalanffy's functions is investigated in detail. We verified that this family of functions has particular bifurcation structures: the big bang bifurcation of the so-called “box-within-a-box” type. The big bang bifurcation is associated to the asymptotic weight or carrying capacity. This work is a contribution to the study of the big bang bifurcation analysis for continuous maps and their relationship with explosion birth and extinction phenomena.

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

Wernher von Braun

NASA Image and Video Library

1964-03-24

Marshall Space Flight Center Director Dr. Wernher von Braun presents Lady Bird Johnson with an inscribed hard hat during the First Lady's March 24, 1964 visit. While at the Marshall Center, Mrs. Johnson addressed Center employees, toured facilities and witnessed test firings of a Saturn I first stage and an F-1 engine. Dr. von Braun is wearing a Texas hat presented to him months earlier by Lyndon Johnson during a visit to the Johnson ranch in Texas.

Long-term (postnatal day 70) outcome and safety of intratracheal transplantation of human umbilical cord blood-derived mesenchymal stem cells in neonatal hyperoxic lung injury.

PubMed

Ahn, So Yoon; Chang, Yun Sil; Kim, Soo Yoon; Sung, Dong Kyung; Kim, Eun Sun; Rime, So Yub; Yu, Wook Joon; Choi, Soo Jin; Oh, Won Il; Park, Won Soon

2013-03-01

This study was performed to evaluate the long-term effects and safety of intratracheal (IT) transplantation of human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs) in neonatal hyperoxic lung injury at postnatal day (P)70 in a rat model. Newborn Sprague Dawley rat pups were subjected to 14 days of hyperoxia (90% oxygen) within 10 hours after birth and allowed to recover at room air until sacrificed at P70. In the transplantation groups, hUCB-MSCs (5×10⁵) were administered intratracheally at P5. At P70, various organs including the heart, lung, liver, and spleen were histologically examined, and the harvested lungs were assessed for morphometric analyses of alveolarization. ED-1, von Willebrand factor, and human-specific nuclear mitotic apparatus protein (NuMA) staining in the lungs and the hematologic profile of blood were evaluated. Impaired alveolar and vascular growth, which evidenced by an increased mean linear intercept and decreased amount of von Willebrand factor, respectively, and the hyperoxia-induced inflammatory responses, as evidenced by inflammatory foci and ED-1 positive alveolar macrophages, were attenuated in the P70 rat lungs by IT transplantation of hUCB-MSCs. Although rare, donor cells with human specific NuMA staining were persistently present in the P70 rat lungs. There were no gross or microscopic abnormal findings in the heart, liver, or spleen, related to the MSCs transplantation. The protective and beneficial effects of IT transplantation of hUCB-MSCs in neonatal hyperoxic lung injuries were sustained for a prolonged recovery period without any long-term adverse effects up to P70.

Increased soluble vascular cell adhesion molecule-1 plasma levels and soluble intercellular adhesion molecule-1 during antiretroviral therapy interruption and retention of elevated soluble vascular cellular adhesion molecule-1 levels following resumption of antiretroviral therapy.

PubMed

Papasavvas, Emmanouil; Azzoni, Livio; Pistilli, Maxwell; Hancock, Aidan; Reynolds, Griffin; Gallo, Cecile; Ondercin, Joe; Kostman, Jay R; Mounzer, Karam; Shull, Jane; Montaner, Luis J

2008-06-19

We investigated the effect of short viremic episodes on soluble markers associated with endothelial stress and cardiovascular disease risk in chronically HIV-1-infected patients followed during continuous antiretroviral therapy, antiretroviral therapy interruption and antiretroviral therapy resumption. We assessed changes in plasma levels of von Willebrand factor, soluble vascular cell adhesion molecule-1 and intercellular adhesion molecule-1 by enzyme-linked immunosorbent assay, as well as T-cell activation (CD8+/CD38+, CD8+/HLA-DR+ and CD3+/CD95+) by flow cytometry, in 36 chronically HIV-1-infected patients participating in a randomized study. Patients were divided into the following three groups: a, on continuous antiretroviral therapy; b, on a 6-week antiretroviral therapy interruption; or c, on antiretroviral therapy interruption extended to the achievement of viral set point. Although all measurements remained stable over a 40-week follow-up on antiretroviral therapy, plasma levels of soluble vascular cell adhesion molecule-1 (P < 0.0001) and soluble intercellular adhesion molecule-1 (P = 0.003) increased during treatment interruption in correlation with viral rebound and T-cell activation. No significant changes in von Willebrand factor were observed in any of the groups. After resuming antiretroviral therapy, soluble vascular cell adhesion molecule-1 levels remained elevated even after achievement of viral suppression to less than 50 copies/ml. The prompt rise in plasma soluble vascular cell adhesion molecule-1 and soluble intercellular adhesion molecule-1 upon viral rebound suggests an acute increase in endothelial stress upon treatment interruption, which may persists after viral resuppression of virus. Thus, viral replication during short-term treatment interruption may increase the overall cardiovascular risk during and beyond treatment interruption.

Thrombospondin-4 reduces binding affinity of [3H]-gabapentin to calcium-channel α2δ-1-subunit but does not interact with α2δ-1 on the cell-surface when co-expressed

PubMed Central

Lana, Beatrice; Page, Karen M.; Kadurin, Ivan; Ho, Shuxian; Nieto-Rostro, Manuela; Dolphin, Annette C.

2016-01-01

The α2δ proteins are auxiliary subunits of voltage-gated calcium channels, and influence their trafficking and biophysical properties. The α2δ ligand gabapentin interacts with α2δ-1, and inhibits calcium channel trafficking. However, α2-1 has also been proposed to play a synaptogenic role, independent of calcium channel function. In this regard, α2δ-1 was identified as a ligand of thrombospondins, with the interaction involving the thrombospondin synaptogenic domain and the α2δ-1 von-Willebrand-factor domain. Co-immunoprecipitation between α2δ-1 and the synaptogenic domain of thrombospondin-2 was prevented by gabapentin. We therefore examined whether interaction of thrombospondin with α2δ-1 might reciprocally influence 3H-gabapentin binding. We concentrated on thrombospondin-4, because, like α2δ-1, it is upregulated in neuropathic pain models. We found that in membranes from cells co-transfected with α2δ-1 and thrombospondin-4, there was a Mg2+ -dependent reduction in affinity of 3H-gabapentin binding to α2δ-1. This effect was lost for α2δ-1 with mutations in the von-Willebrand-factor-A domain. However, the effect on 3H-gabapentin binding was not reproduced by the synaptogenic EGF-domain of thrombospondin-4. Partial co-immunoprecipitation could be demonstrated between thrombospondin-4 and α2δ-1 when co-transfected, but there was no co-immunoprecipitation with thrombospondin-4-EGF domain. Furthermore, we could not detect any association between these two proteins on the cell-surface, indicating the demonstrated interaction occurs intracellularly. PMID:27076051

Comparison of three types of stress urinary incontinence rat models: electrocauterization, pudendal denervation, and vaginal distension.

PubMed

Hong, Sung-Hoo; Piao, Shuyu; Kim, In Gul; Lee, Ji Young; Cho, Hyuk Jin; Kim, Sae Woong; Hwang, Tae-Kon; Lee, Ji Youl

2013-02-01

To investigate the differences in the histopathologic and functional characteristics of 3 rat models of stress urinary incontinence. A total of 24 female, 10-week-old, Sprague-Dawley rats were randomly divided into 4 groups: normal, electrocauterization, pudendal denervation, and vaginal distension. At 2 weeks after surgery, the leak point pressure was measured to detect urinary leakage. Urethral tissue samples were collected for histological examination. The smooth muscle content in the electrocauterization group was significantly decreased compared with that in all other groups, indicating that electrocauterization caused the most severe injury. A blood vessel marker, von Willebrand factor, was co-stained with α-smooth muscle actin to detect the blood vessel distribution. No significant differences were seen in von Willebrand factor expression among the 4 groups, other than in the electrocauterization group, in which we could hardly observe blood vessel expression. Protein gene product 9.5 staining was used to detect nerve fibers and cells. Protein gene product 9.5 expression was significantly lower in all the treatment groups compared with that in the normal group (P <.05), in particular, in the electrocauterization and pudendal denervation groups (P <.01). The leak point pressure was significantly lower in the electrocauterization (P <.01), pudendal denervation (P <.01), and vaginal distension (P <.05) groups than in the normal group. The vaginal distension model should mainly be used as the myogenic damage stress urinary incontinence animal model; the pudendal denervation model mainly as the neurogenic damage stress urinary incontinence animal model; and the electrocauterization model as the vasculogenic, neurogenic, and myogenic damage animal model. Copyright © 2013. Published by Elsevier Inc.

Intra-plaque production of platelet-activating factor correlates with neoangiogenesis in human carotid atherosclerotic lesions.

PubMed

Lupia, Enrico; Pucci, Angela; Peasso, Paolo; Merlo, Maurizio; Baron, Paolo; Zanini, Cristina; Del Sorbo, Lorenzo; Rizea-Savu, Simona; Silvestro, Luigi; Forni, Marco; Emanuelli, Giorgio; Camussi, Giovanni; Montrucchio, Giuseppe

2003-09-01

Platelet-activating factor (PAF) is a phospholipid mediator synthesized by activated inflammatory and endothelial cells. Recently PAF has been shown to contribute to neoangiogenesis in several experimental models. Here we evaluated the presence of PAF and its potential role in neovascularization within human atherosclerotic plaques. The amount of PAF extracted from 18 carotid plaques (266.65+/-40.07 pg/100 mg dry tissue; mean +/- SE) was significantly higher than that extracted from 18 normal arterial specimens (6 from carotid artery and 12 from aorta) (4.72+/-2.31 pg/100 mg dry tissue; mean +/- SE). The levels of PAF significantly correlated with the infiltration of CD68-positive monocytes and the extent of neovascularization, detected as von Willebrand Factor-positive cells. The amount of PAF also correlated with the area occupied by TNF-alpha-expressing cells. The absence of enhanced level of PAF in the circulation of atherosclerotic patients suggests a local production of this mediator within the plaque. The lipid extracts of atherosclerotic plaques containing high levels of PAF-bioactivity, but not those of control arteries, were angiogenic in a murine Matrigel model. WEB 2170, a specific PAF receptor antagonist, significantly prevented angiogenesis induced by the lipid extracts of atherosclerotic plaques. Our results indicate a local production of PAF within the atherosclerotic plaques and suggest that it may contribute to intra-plaque neoangiogenesis.

Immune tolerance: critical issues of factor dose, purity and treatment complications.

PubMed

DiMichele, D M

2006-12-01

The current practice of immune tolerance induction (ITI) therapy has been largely influenced by the results of small institutional studies and three large registries. However, many questions remain. Successful outcome predictors for ITI in haemophilia A have been suggested by the analyses of two of these registries. Among these predictors, factor VIII (FVIII) dose/dosing regimen remains a controversial outcome parameter, demonstrating a strong direct relationship to ITI success in the international registry and a weaker inverse relationship in the North American registry. There is an international multicentre prospective randomized trial underway to further study the role of FVIII dose in successful ITI induction in a good risk haemophilia A inhibitor patient cohort. FVIII purity also remains an unproved ITI outcome predictor. Institutional experience with von-Willebrand-factor-containing products has suggested its therapeutic advantage in both inhibitor development and eradication. The International ITI Study, although not designed to answer this particular question, may be able to determine an impact on outcome depending on the final distribution of investigator choice of product among the study subjects. Much less is known about the influence of factor IX (FIX) dose and purity on ITI success in haemophilia B. Importantly, nephrotic syndrome has been a major determinant of ITI failure in FIX inhibitor patients, particularly those with the allergic phenotype. Unfortunately, large prospective randomized trials in this group will not be feasible. Rather, we will have to rely on prospectively collected registry data to build our knowledge base of inhibitors and ITI in haemophilia B.

Molecular aspects in clinical hemostasis research at Karolinska Institutet.

PubMed

Blombäck, Margareta

2010-05-21

The development of hemostasis research at Karolinska Institutet is described, focusing first on the initial findings of the fibrinogen structure and the hereditary bleeding disorders, hemophilia A and von Willebrand's disease. Basic research has focused on new biomarkers for cardiovascular/thromboembolic disorders, such as myocardial infarction and stroke, including preeclampsia and diabetes, with studies on the importance of decreased fibrinolysis in these disorders. Since long, the structure of the fibrin network has been evaluated, and recently the influence of aspirin and new thrombin and factor Xa inhibitors has been investigated. Research on the contact pathway of coagulation has also started at the Unit. 2010 Elsevier Inc. All rights reserved.

Wernher von Braun

NASA Image and Video Library

1958-01-31

Jet Propulsion Laboratory Director Dr. James Pickering, Dr. James van Allen of the State University of Iowa, and Army Ballistic missionile Agency Technical Director Dr. Wernher von Braun triumphantly display a model of the Explorer I, America's first satellite, shortly after the satellite's launch on January 31, 1958. The Jet Propulsion Laboratory packed and tested the payload, a radiation detection experiment designed by Dr. van Allen. Dr. von Braun's rocket team at Redstone Arsenal in Huntsville, Alabama, developed the Juno I launch vehicle, a modified Jupiter-C.

Liquid Biopsy zur Überwachung von Melanompatienten.

PubMed

Gaiser, Maria Rita; von Bubnoff, Nikolas; Gebhardt, Christoffer; Utikal, Jochen Sven

2018-04-01

In den letzten sechs Jahren wurden verschiedene innovative systemische Therapien zur Behandlung des metastasierten malignen Melanoms (MM) entwickelt. Die konventionelle Chemotherapie wurde durch neuartige Primärtherapien abgelöst, darunter systemische Immuntherapien (Anti-CTLA4- und Anti-PD1-Antikörper; Zulassung von Anti-PDL1-Antikörpern erwartet) und Therapien, die gegen bestimmte Mutationen gerichtet sind (BRAF, NRAS und c-KIT). Daher stehen die behandelnden Ärzte neuen Herausforderungen gegenüber, beispielsweise der Stratifizierung von Patienten für geeignete Behandlungen und der Überwachung von Langzeit-Respondern auf Progression. Folglich werden zuverlässige Methoden zur Überwachung von Krankheitsprogression oder Behandlungsresistenz benötigt. Lokalisierte und fortgeschrittene Krebserkrankungen können zur Bildung zirkulierender Tumorzellen und Tumor-DNA (ctDNA) führen, die sich in Proben von peripherem Blut nachweisen und quantifizieren lassen (Liquid Biopsy). Im Fall von Melanompatienten können die Ergebnisse von Liquid Biopsy als neuartige prädiktive Biomarker bei therapeutischen Entscheidungen hilfreich sein, insbesondere im Zusammenhang mit mutationsbasierten zielgerichteten Therapien. Die Herausforderungen bei der Anwendung der Liquid Biopsy beinhalten strikte Kriterien für den Phänotyp der zirkulierenden MM-Zellen oder ihrer Fragmente und die Instabilität von ctDNA im Blut. In diesem Übersichtsartikel diskutieren wir die Beschränkungen der Liquid Biopsy hinsichtlich ihrer Anwendung in der Routinediagnostik. © 2018 Deutsche Dermatologische Gesellschaft (DDG). Published by John Wiley & Sons Ltd.

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.

Venom Concentrations and Clotting Factor Levels in a Prospective Cohort of Russell's Viper Bites with Coagulopathy.

PubMed

Isbister, Geoffrey K; Maduwage, Kalana; Scorgie, Fiona E; Shahmy, Seyed; Mohamed, Fahim; Abeysinghe, Chandana; Karunathilake, Harendra; O'Leary, Margaret A; Gnanathasan, Christeine A; Lincz, Lisa F

2015-01-01

Russell's viper envenoming is a major problem in South Asia and causes venom induced consumption coagulopathy. This study aimed to investigate the kinetics and dynamics of venom and clotting function in Russell's viper envenoming. In a prospective cohort of 146 patients with Russell's viper envenoming, we measured venom concentrations, international normalised ratio [INR], prothrombin time (PT), activated partial thromboplastin time (aPTT), coagulation factors I, II, V, VII, VIII, IX and X, and von Willebrand factor antigen. The median age was 39 y (16-82 y) and 111 were male. The median peak INR was 6.8 (interquartile range [IQR]: 3.7 to >13), associated with low fibrinogen [median,<0.01 g/L; IQR: <0.01-0.9 g/L), low factor V levels [median,<5%; IQR: <5-4%], low factor VIII levels [median,40%; IQR: 12-79%] and low factor X levels [median, 48%; IQR: 29-67%]. There were smaller reductions in factors II, IX and VII over time. All factors recovered over 48 h post-antivenom. The median INR remained >3 at 6 h post-antivenom but had reduced to <2, by 24 h. The aPTT had also returned to close to normal (<50 sec) at 24 h. Factor VII, VIII and IX levels were unusually high pre-antivenom, median peak concentrations of 393%, 307% and 468% respectively. Pre-antivenom venom concentrations and the INR (r = 0.20, p = 0.02) and aPTT (r = 0.19, p = 0.03) were correlated (non-parametric Spearman analysis). Russell's viper coagulopathy results in prolonged aPTT, INR, low fibrinogen, factors V, VIII and X which recover over 48 h. Severity of clotting abnormalities was associated with venom concentrations.

Wernher von Braun

NASA Image and Video Library

1970-06-27

This photograph was taken after Dr. von Braun moved from his post as Director of the Marshall Space Flight Center (MSFC) to Deputy Associate Administrator for Planning at NASA Headquarters. On June 27, 1970, he visited the MSFC again during the center’s 10th anniversary to look at a mockup of the spacecraft that would later be known as Skylab. With von Braun are (left to right): Herman K. Weidner, director of Science and Engineering at MSFC, and James R. Thompson of the center’s Astrionics Laboratory.

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.

The effect of hyperthyroidism on procoagulant, anticoagulant and fibrinolytic factors: a systematic review and meta-analysis.

PubMed

Stuijver, Danka J F; van Zaane, Bregje; Romualdi, Erica; Brandjes, Dees P M; Gerdes, Victor E A; Squizzato, Alessandro

2012-12-01

Several coagulation and fibrinolytic parameters appear to be affected by thyroid hormone excess; however, the net effect on the haemostatic system remains unclear. We aimed to update our previous review and systematically summarise and meta-analyse the data by assessing the effects of thyrotoxicosis on the coagulation and fibrinolytic system in vivo . Data sources included MEDLINE (2006-2012), EMBASE (2006-2012), and reference lists. The sources were combined with our previous search containing studies from 1980-2006. Eligible studies were all observational or experimental studies. Two investigators independently extracted data and rated study quality. Weighted mean proportion and 95% confidence intervals were calculated and pooled using a fixed and a random-effects model. A total of 29 articles consisting of 51 studies were included, as in several articles more than one study was described. We included four intervention (before and after treatment in hyperthyroid patients), five cross-sectional (hyperthyroid subjects and euthyroid controls), and four experimental (before and after use of thyroid hormone in euthyroid subjects) medium/high quality studies for meta-analysis. We found that thyrotoxicosis shifts the haemostatic balance towards a hypercoagulable and hypofibrinolytic state with a rise in factors VIII and IX, fibrinogen, von Willebrand factor, and plasminogen activator inhibitor-1. This was observed in endogenous and exogenous thyrotoxicosis, and in subclinical as well as overt hyperthyroidism. We conclude that both subclinical and overt hyperthyroidism induce a prothrombotic state, which is therefore likely to be a risk factor for venous thrombosis.

Polycystic ovary syndrome: cardiovascular risk factors according to specific phenotypes.

PubMed

Aziz, Mubeena; Sidelmann, Johannes J; Faber, Jens; Wissing, Marie-Louise M; Naver, Klara V; Mikkelsen, Anne-Lis; Nilas, Lisbeth; Skouby, Sven O

2015-10-01

Polycystic ovary syndrome (PCOS) is associated with obesity and insulin resistance. The objective of this cross-sectional study was to investigate the impact of insulin resistance and body mass index (BMI) on inflammatory and hemostatic variables associated with long-term risk of cardiovascular disease in women with PCOS. 149 premenopausal women with PCOS were recruited consecutively from April 2010 to February 2012 at three Danish University Hospitals. The study was conducted at the Department of Gynecology and Obstetrics, Herlev University Hospital, Denmark. PCOS was diagnosed in accordance with the Rotterdam criteria and the women were classified into four phenotypes according to BMI and insulin resistance measured by the homeostasis model assessment of insulin resistance index. Body composition was determined by dual-energy X-ray absorptiometry. Main outcome measures were the biomarkers C-reactive protein (CRP), plasminogen activator inhibitor-1 (PAI-1), and von Willebrand factor antigen. Normal weight insulin-resistant PCOS women were characterized by abdominal obesity and elevated levels of plasma PAI-1. Overweight/obese insulin-resistant PCOS women had increased levels of both PAI-1 and CRP. Of the three Rotterdam criteria, only hyperandrogenemia was significantly associated with the hemostatic risk marker of long-term cardiovascular disease risk. Surrogate risk markers for cardiovascular disease are elevated in women with PCOS, especially insulin-resistant and overweight/obese women. © 2015 Nordic Federation of Societies of Obstetrics and Gynecology.

Analyse der pharmazeutischen Versorgungssituation von Patienten mit Psoriasis-Arthritis auf Basis von Routinedaten der Gesetzlichen Krankenversicherung.

PubMed

Sondermann, Wiebke; Ventzke, Julia; Matusiewicz, David; Körber, Andreas

2018-03-01

Die Psoriasis-Arthritis (PsA) gehört zu den chronisch entzündlichen Gelenkerkrankungen. Trotz zahlreicher versorgungswissenschaftlicher Studien in Deutschland liegen zur pharmazeutischen Versorgungssituation von PsA-Patienten bisher kaum aktuelle Ergebnisse vor. Mit Hilfe einer systematischen Literaturrecherche sowie anhand von Routinedaten der Allgemeinen Ortskrankenkasse (AOK) Rheinland/Hamburg wird ein aktueller Überblick über die pharmazeutische Versorgung von PsA-Patienten in Deutschland gegeben. Selektiert wurden Versicherte aus dem ambulanten und stationären Bereich, die im 1. und 2. Quartal des Jahres 2014 die gesicherte Abrechnungsdiagnose Psoriasis-Arthritis L40.5+ aufwiesen. Anschließend wurden auf Basis dieser "vorab definierten" Kohorte die Arzneimitteldaten für 5 Jahre (01.01.2010-31.12.2014) abgerufen. Es konnten insgesamt n  =  3205 Versicherte (45 % männlich, 55 % weiblich) der AOK Rheinland/Hamburg mit einer gesicherten PsA-Diagnose selektiert werden. Das Durchschnittsalter betrug 58,9 Jahre. 53,7 % der PsA-Patienten wurden mit systemischen PsA-relevanten Arzneimitteln versorgt. Nichtsteroidale Antirheumatika (NSAR) wurden am häufigsten verordnet, gefolgt von systemischen Glucocorticoiden. Von den selektierten PsA-Patienten, die eine Systemtherapie erhielten, wurden 72,1 % mittels einer Disease-modifying-antirheumatic-Drug (DMARD)-Monotherapie behandelt, gefolgt von der Kombinationstherapie aus DMARDs und Biologika (20,9 %). Die pharmakologische Therapie der PsA muss eine Gewährleistung zwischen adäquater Versorgung der PsA mit Verhinderung der Krankheitsprogression und ökonomischer Verantwortung darstellen. © 2018 Deutsche Dermatologische Gesellschaft (DDG). Published by John Wiley & Sons Ltd.

MLN8054, A Small Molecule Inhibitor of Aurora Kinase A, Sensitizes Androgen-Resistant Prostate Cancer to Radiation;Aurora kinase A; MLN8054; Prostate cancer; Radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moretti, Luigi; Department of Radiation Oncology, Institut Jules Bordet, Universite Libre de Bruxelles, Brussels; Niermann, Kenneth

2011-07-15

Purpose: To determine whether MLN8054, an Aurora kinase A (Aurora-A) inhibitor causes radiosensitization in androgen-insensitive prostate cancer cells in vitro and in vivo. Methods and Materials: In vitro studies consisted of culturing PC3 and DU145 prostate cancer cells and then immunoblotting Aurora A and phospho-Aurora A after radiation and/or nocodazole with MLN8054. Phases of the cell cycle were measured with flow cytometry. PC3 and DU145 cell lines were measured for survival after treatment with MLN8054 and radiation. Immunofluorescence measured {gamma}-H2AX in the PC3 and DU145 cells after treatment. In vivo studies looked at growth delay of PC3 tumor cells inmore » athymic nude mice. PC3 cells grew for 6 to 8 days in mice treated with radiation, MLN8054, or combined for 7 more days. Tumors were resected and fixed on paraffin and stained for von Willebrand factor, Ki67, and caspase-3. Results: In vitro inhibition of Aurora-A by MLN8054 sensitized prostate cancer cells, as determined by dose enhancement ratios in clonogenic assays. These effects were associated with sustained DNA double-strand breaks, as evidenced by increased immunofluorescence for {gamma}-H2AX and significant G2/M accumulation and polyploidy. In vivo, the addition of MLN8054 (30 mg/kg/day) to radiation in mouse prostate cancer xenografts (PC3 cells) significantly increased tumor growth delay and apoptosis (caspase-3 staining), with reduction in cell proliferation (Ki67 staining) and vascular density (von Willebrand factor staining). Conclusion: MLN8054, a novel small molecule Aurora-A inhibitor showed radiation sensitization in androgen-insensitive prostate cancer in vitro and in vivo. This warrants the clinical development of MLN8054 with radiation for prostate cancer patients.« less

Circulating platelet aggregates damage endothelial cells in culture.

PubMed

Aluganti Narasimhulu, Chandrakala; Nandave, Mukesh; Bonilla, Diana; Singaravelu, Janani; Sai-Sudhakar, Chittoor B; Parthasarathy, Sampath

2017-06-01

Presence of circulating endothelial cells (CECs) in systemic circulation may be an indicator of endothelial damage and/or denudation, and the body's response to repair and revascularization. Thus, we hypothesized that aggregated platelets (AgPlts) can disrupt/denude the endothelium and contribute to the presence of CEC and EC-derived particles (ECDP). Endothelial cells were grown in glass tubes and tagged with/without 0.5 μm fluorescent beads. These glass tubes were connected to a mini-pump variable-flow system to study the effect of circulating AgPlts on the endothelium. ECs in glass tube were exposed to medium alone, nonaggregated platelets (NAgPlts), AgPlts, and 90 micron polystyrene beads at a flow rate of 20 mL/min for various intervals. Collected effluents were cultured for 72 h to analyze the growth potential of dislodged but intact ECs. Endothelial damage was assessed by real time polymerase chain reaction (RT-PCR) for inflammatory genes and Western blot analysis for von Willebrand factor. No ECs and ECDP were observed in effluents collected after injecting medium alone and NAgPlts, whereas AgPlts and Polybeads drastically dislodged ECs, releasing ECs and ECDP in effluents as the time increased. Effluents collected when endothelial cell damage was seen showed increased presence of von Willebrand factor as compared to control effluents. Furthermore, we analyzed the presence of ECs and ECDPs in heart failure subjects, as well as animal plasma samples. Our study demonstrates that circulating AgPlts denude the endothelium and release ECs and ECDP. Direct mechanical disruption and shear stress caused by circulating AgPlts could be the underlying mechanism of the observed endothelium damage. Copyright © 2017 Elsevier Inc. All rights reserved.

Cross-reacting Material-positive Hemophilia A Diagnosed in a Patient with a Spontaneous Thigh Hemorrhage

PubMed Central

Saito, Tatsuya; Mukae, Jyunichi; Nakamura, Yosuke; Inaba, Hiroshi; Nogami, Keiji; Koyama, Takatoshi; Fukutake, Katsuyuki; Yamamoto, Koh

2017-01-01

A 53-year-old man, who had been diagnosed with mild hemophilia A (HA) at 35 years of age, was hospitalized with a thigh hematoma. His bleeding continued despite the administration of recombinant factor VIII (FVIII). The results of an FVIII/von Willebrand factor binding assay were normal. The patient's FVIII coagulant activity (FVIII:C) was low, but his FVIII antigen levels were within the normal limits, suggesting FVIII protein dysfunction. The FVIII:C measurements obtained by one-stage clotting and chromogenic assays were different. An FVIII gene analysis revealed a missense mutation p.Ser308Leu, which is rare in Japan. This case highlights that gene analyses and chromogenic assays are necessary to interpret the discrepancies between FVIII:C and the bleeding phenotype of patients with mild HA. PMID:28674365

Cross-reacting Material-positive Hemophilia A Diagnosed in a Patient with a Spontaneous Thigh Hemorrhage.

PubMed

Saito, Tatsuya; Mukae, Jyunichi; Nakamura, Yosuke; Inaba, Hiroshi; Nogami, Keiji; Koyama, Takatoshi; Fukutake, Katsuyuki; Yamamoto, Koh

2017-01-01

A 53-year-old man, who had been diagnosed with mild hemophilia A (HA) at 35 years of age, was hospitalized with a thigh hematoma. His bleeding continued despite the administration of recombinant factor VIII (FVIII). The results of an FVIII/von Willebrand factor binding assay were normal. The patient's FVIII coagulant activity (FVIII:C) was low, but his FVIII antigen levels were within the normal limits, suggesting FVIII protein dysfunction. The FVIII:C measurements obtained by one-stage clotting and chromogenic assays were different. An FVIII gene analysis revealed a missense mutation p.Ser308Leu, which is rare in Japan. This case highlights that gene analyses and chromogenic assays are necessary to interpret the discrepancies between FVIII:C and the bleeding phenotype of patients with mild HA.

Hematology Expert System (HES) For Tonsillectomy/Adenoidectomy Patients

NASA Astrophysics Data System (ADS)

Pizzi, Nicolino J.; Kapoor, Sandhya; Gerrard, Jon M.

1989-03-01

The purpose of this expert system is to assess a predisposition to bleeding in a patient undergoing a tonsillectomy and/or adenoidectomy as may occur with patients who have certain blood conditions such as hemophilia and von Willebrand's disease. This goal is achieved by establishing a correlation between the patients' responses to a medical questionnaire and the relative quantities of blood lost during the operation.

Clarifying the link between von Neumann and thermodynamic entropies

NASA Astrophysics Data System (ADS)

Deville, Alain; Deville, Yannick

2013-01-01

The state of a quantum system being described by a density operator ρ, quantum statistical mechanics calls the quantity - kTr( ρln ρ), introduced by von Neumann, its von Neumann or statistical entropy. A 1999 Shenker's paper initiated a debate about its link with the entropy of phenomenological thermodynamics. Referring to Gibbs's and von Neumann's founding texts, we replace von Neumann's 1932 contribution in its historical context, after Gibbs's 1902 treatise and before the creation of the information entropy concept, which places boundaries into the debate. Reexamining von Neumann's reasoning, we stress that the part of his reasoning implied in the debate mainly uses thermodynamics, not quantum mechanics, and identify two implicit postulates. We thoroughly examine Shenker's and ensuing papers, insisting upon the presence of open thermodynamical subsystems, imposing us the use of the chemical potential concept. We briefly mention Landau's approach to the quantum entropy. On the whole, it is shown that von Neumann's viewpoint is right, and why Shenker's claim that von Neumann entropy "is not the quantum-mechanical correlate of thermodynamic entropy" can't be retained.

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

2018-04-15

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. Copyright © 2017 Elsevier Inc. All rights reserved.

Bleeding complications in BCR-ABL negative myeloproliferative neoplasms: prevalence, type, and risk factors in a single-center cohort.

PubMed

Kander, Elizabeth M; Raza, Sania; Zhou, Zheng; Gao, Juehua; Zakarija, Anaadriana; McMahon, Brandon J; Stein, Brady L

2015-11-01

The BCR-ABL1-negative myeloproliferative neoplasms (MPN) share an increased risk of thrombotic and hemorrhagic complications. Risk factors for hemorrhage are less well defined than those for thrombosis. Because patients with CALR mutations have higher platelet counts compared to JAK2 V617F-mutated patients, bleeding rates may be increased in this group. Our aim was to retrospectively evaluate whether acquired von Willebrand disease (AvWD), thrombocytosis, mutational status, or treatment history are associated with bleeding in a cohort of MPN patients. Using an electronic database, MPN patients seen between 2005 and 2013 were retrospectively identified using ICD-9 codes and billing records. A bleeding event was defined as one that was identified in the medical record and graded based on the Common Terminology Criteria for Adverse Event (CTCAE) version 4.0. Among 351 MPN patients, 15.6 % experienced 64 bleeding event types. There was no association of bleeding with mutational status, gender, MPN subtype, aspirin use, prior thrombosis, or platelet count at presentation. There was an association between bleeding and older age at diagnosis. aVWD was identified in six patients. In this single-center retrospective study, bleeding events were identified in 15 % of patients, and associated with older age at diagnosis. aVWD was rarely tested for in this cohort.

[Albert Reder Ritter von Schellmann (1826-1904)].

PubMed

Schmidt, G; Holubar, K

1990-01-01

Albert Reder von Schellmann (1826-1904) was an important syphilidologist of the Vienna Medical School in the second half of the nineteenth century. He went in for the dualistic concept of the origin of syphilis and ulcer caused by soft chancre. In 1870 - Reder became head of a third dermato-syphilidologic department in the "Josephinum" in Vienna, where military surgeons got their medical education. At the same time the two full professorships of dermatosyphilidology in the Vienna General Hospital were held by Ferdinand von Hebra (1816-1880) and Carl Ludwig Sigmund von Ilanor (1810-1883).

Characterization of factor VIII pharmaceutical preparations by means of MudPIT proteomic approach.

PubMed

Basilico, Fabrizio; Nardini, Ilaria; Mori, Filippo; Brambilla, Elena; Benazzi, Louise; De Palma, Antonella; Rosti, Enrico; Farina, Claudio; Mauri, PierLuigi

2010-09-21

For a good clinical outcome of Haemophilia A substitutive therapy a detailed characterization of factor VIII (FVIII) concentrates is required, in order to disclose the eventual relations between differently composed concentrates and their biological effects. This preliminary work could be a first step towards a deep structural characterization of FVIII concentrates, using the fast and simply manageable MudPIT technology, which enables the identification and characterization of protein mixtures taking advantage of both the high separation capacity of two-dimensional chromatography and the powerful peptide characterization ability of tandem mass spectrometry. The aim of this study was to evaluate the suitability of for the characterization of FVIII molecule in complex mixtures such its commercial concentrates, both plasma-derived and recombinant, and for the determination of the protein composition of different FVIII preparations. By means of Multidimensional Protein Identification Technology (MudPIT) it was possible to assess the presence of factor VIII in its preparations and to identify most of the contaminant proteins without gel separation. In particular, 125 and 42 proteins were identified in plasma-derived and recombinant concentrates, respectively. Concerning investigation of FVIII, 24 different peptides were identified in plasma-derived corresponding to 7, 29, 27, 19 and 67 of percentage coverage for A1, A2, A3, C1 and C2 domains, respectively. About its multimeric carrier von Willebrand factor (VWF), we have sequenced 42% of domain interacting with A3 and C2 domains of FVIII. Finally, it has been observed that normalized parameters, such as total peptide hits obtained by SEQUEST may be used for evaluation of the relative abundance of FVIII in different preparations. Copyright 2010 Elsevier B.V. All rights reserved.

Wernher von Braun

NASA Image and Video Library

1962-12-20

Dr. von Braun, Major General Francis McMorrow, and Alabama Governor, John Patterson (far left) participated in the ground breaking ceremony for the University of Alabama Research Institute in Huntsville, December 20, 1962.

Wernher von Braun

NASA Image and Video Library

1965-11-05

In this photograph, Marshall Space Flight Center Director, Dr. Wernher von Braun, presents a Co-Inventor’s award to MSFC employee Martin Hall of the Mechanical Engineering Laboratory during the NASA Anniversary ceremony.

A French National Survey on Clotting Disorders in Mastocytosis.

PubMed

Carvalhosa, Ana B; Aouba, Achille; Damaj, Gandhi; Canioni, Danielle; Brouzes, Chantal; Gyan, Emmanuel; Durupt, Stéphane; Durieu, Isabelle; Cathebras, Pascal; Costédoat-Chalumeau, Nathalie; Launay, David; Pilmis, Benoit; Barete, Stephane; Frenzel, Laurent; Lortholary, Olivier; Hermine, Olivier; Hermans, Cedric; Chandesris, Marie-Olivia

2015-10-01

Mastocytosis is characterized by a clonal mast cell proliferation with organ infiltration and uncontrolled degranulation. Although not characteristic and poorly explained, some patients develop clotting abnormalities. We retrospectively identified patients with established diagnosis of mastocytosis and related clotting abnormalities (clinical and/or biological) using the national French Reference Centre for Mastocytosis database. From our cohort of 14 adult patients with clotting abnormalities (median age 46 years [range 26-75]), 4 had a presentation suggestive of a primary hemostasis disorder alone (by their symptoms and/or abnormal clotting tests [PFA, von Willebrand's disease [vWD] screening]) and 10 had a laboratory impairment of secondary hemostasis. Among these, 7 had bleeds characteristic of a coagulation cascade disorder (severe/life-threatening in 5 and mild in 2 patients). Clotting abnormalities were of variable severity, typically related to intense crisis of degranulation, such as anaphylactic reactions, and/or to severe organ infiltration by mast cells. Importantly, classical hemostatic management with platelet transfusion, fresh frozen plasma, or vitamin K infusions was unsuccessful, as opposed to the use of agents inhibiting mast cell activity, particularly steroids. This illustrates the crucial role of mast cell mediators such as tryptase and heparin, which interfere both with primary (mainly via inhibition of von Willebrand factor) and secondary hemostasis. There was interestingly an unusually high number of aggressive mastocytosis (particularly mast cell leukemia) and increased mortality in the group with secondary hemostasis disorders (n = 5, 36% of the whole cohort). Mast cell degranulation and/or high tumoral burden induce both specific biologic antiaggregant and anticoagulant states with a wide clinical spectrum ranging from asymptomatic to life-threatening bleeds. Hemostatic control is achieved by mast cell inhibitors such as steroids.

Clinical and laboratory variability in a cohort of patients diagnosed with type 1 VWD in the United States

PubMed Central

Christopherson, Pamela A.; Gill, Joan Cox; Friedman, Kenneth D.; Haberichter, Sandra L.; Bellissimo, Daniel B.; Udani, Rupa A.; Dasgupta, Mahua; Hoffmann, Raymond G.; Ragni, Margaret V.; Shapiro, Amy D.; Lusher, Jeanne M.; Lentz, Steven R.; Abshire, Thomas C.; Leissinger, Cindy; Hoots, W. Keith; Manco-Johnson, Marilyn J.; Gruppo, Ralph A.; Boggio, Lisa N.; Montgomery, Kate T.; Goodeve, Anne C.; James, Paula D.; Lillicrap, David; Peake, Ian R.; Montgomery, Robert R.

2016-01-01

von Willebrand disease (VWD) is the most common inherited bleeding disorder, and type 1 VWD is the most common VWD variant. Despite its frequency, diagnosis of type 1 VWD remains the subject of debate. In order to study the spectrum of type 1 VWD in the United States, the Zimmerman Program enrolled 482 subjects with a previous diagnosis of type 1 VWD without stringent laboratory diagnostic criteria. von Willebrand factor (VWF) laboratory testing and full-length VWF gene sequencing was performed for all index cases and healthy control subjects in a central laboratory. Bleeding phenotype was characterized using the International Society on Thrombosis and Haemostasis bleeding assessment tool. At study entry, 64% of subjects had VWF antigen (VWF:Ag) or VWF ristocetin cofactor activity below the lower limit of normal, whereas 36% had normal VWF levels. VWF sequence variations were most frequent in subjects with VWF:Ag <30 IU/dL (82%), whereas subjects with type 1 VWD and VWF:Ag ≥30 IU/dL had an intermediate frequency of variants (44%). Subjects whose VWF testing was normal at study entry had a similar rate of sequence variations as the healthy controls (14%). All subjects with severe type 1 VWD and VWF:Ag ≤5 IU/dL had an abnormal bleeding score (BS), but otherwise BS did not correlate with VWF:Ag. Subjects with a historical diagnosis of type 1 VWD had similar rates of abnormal BS compared with subjects with low VWF levels at study entry. Type 1 VWD in the United States is highly variable, and bleeding symptoms are frequent in this population. PMID:26862110

Clinical and laboratory variability in a cohort of patients diagnosed with type 1 VWD in the United States.

PubMed

Flood, Veronica H; Christopherson, Pamela A; Gill, Joan Cox; Friedman, Kenneth D; Haberichter, Sandra L; Bellissimo, Daniel B; Udani, Rupa A; Dasgupta, Mahua; Hoffmann, Raymond G; Ragni, Margaret V; Shapiro, Amy D; Lusher, Jeanne M; Lentz, Steven R; Abshire, Thomas C; Leissinger, Cindy; Hoots, W Keith; Manco-Johnson, Marilyn J; Gruppo, Ralph A; Boggio, Lisa N; Montgomery, Kate T; Goodeve, Anne C; James, Paula D; Lillicrap, David; Peake, Ian R; Montgomery, Robert R

2016-05-19

von Willebrand disease (VWD) is the most common inherited bleeding disorder, and type 1 VWD is the most common VWD variant. Despite its frequency, diagnosis of type 1 VWD remains the subject of debate. In order to study the spectrum of type 1 VWD in the United States, the Zimmerman Program enrolled 482 subjects with a previous diagnosis of type 1 VWD without stringent laboratory diagnostic criteria. von Willebrand factor (VWF) laboratory testing and full-length VWF gene sequencing was performed for all index cases and healthy control subjects in a central laboratory. Bleeding phenotype was characterized using the International Society on Thrombosis and Haemostasis bleeding assessment tool. At study entry, 64% of subjects had VWF antigen (VWF:Ag) or VWF ristocetin cofactor activity below the lower limit of normal, whereas 36% had normal VWF levels. VWF sequence variations were most frequent in subjects with VWF:Ag <30 IU/dL (82%), whereas subjects with type 1 VWD and VWF:Ag ≥30 IU/dL had an intermediate frequency of variants (44%). Subjects whose VWF testing was normal at study entry had a similar rate of sequence variations as the healthy controls (14%). All subjects with severe type 1 VWD and VWF:Ag ≤5 IU/dL had an abnormal bleeding score (BS), but otherwise BS did not correlate with VWF:Ag. Subjects with a historical diagnosis of type 1 VWD had similar rates of abnormal BS compared with subjects with low VWF levels at study entry. Type 1 VWD in the United States is highly variable, and bleeding symptoms are frequent in this population. © 2016 by The American Society of Hematology.

Tuning the endothelial response: differential release of exocytic cargos from Weibel-Palade Bodies.

PubMed

Nightingale, Thomas D; McCormack, Jessica J; Grimes, William; Robinson, Christopher; Lopes da Silva, Mafalda; White, Ian J; Vaughan, Andrew; Cramer, Louise P; Cutler, Daniel F

2018-06-28

Endothelial cells harbour specialised storage organelles, Weibel-Palade Bodies (WPBs). Exocytosis of WPB content into the vascular lumen initiates primary haemostasis, mediated by Von Willebrands factor (VWF) and inflammation, mediated by several proteins including P-selectin. During full fusion, secretion of this large haemostatic protein and smaller pro-inflammatory proteins are thought to be inextricably linked. To determine if secretagogue-dependent differential release of WPB cargo occurs, and whether this is mediated by the formation of an actomyosin ring during exocytosis. We used VWF string analysis, leukocyte rolling assays, ELISA, spinning disk confocal microscopy, high-throughput confocal microscopy and inhibitor and siRNA treatments to demonstrate the existence of cellular machinery that allows differential release of WPB cargo proteins. Inhibition of the actomyosin ring differentially effects two processes regulated by WPB exocytosis; it perturbs VWF string formation but has no effect on leukocyte rolling. The efficiency of ring recruitment correlates with VWF release; the ratio of release of VWF to small cargoes decreases when ring recruitment is inhibited. The recruitment of the actin ring is time-dependent; fusion events occurring directly after stimulation are less likely to initiate haemostasis than later events, and is activated by PKC isoforms. Secretagogues differentially recruit the actomyosin ring, thus demonstrating one mechanism by which the pro-thrombotic effect of endothelial activation can be modulated. This potentially limits thrombosis whilst permitting a normal inflammatory response. These results have implications for the assessment of WPB fusion, cargo-content release and the treatment of patients with von Willebrand disease. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Platelet-free shear flow assay facilitates analysis of shear-dependent functions of VWF and ADAMTS13.

PubMed

Kraus, Emma; Kraus, Kristina; Obser, Tobias; Oyen, Florian; Klemm, Ulrike; Schneppenheim, Reinhard; Brehm, Maria A

2014-12-01

The multimeric form of von Willebrand factor (VWF), is the largest soluble protein in mammals and exhibits a multidomain structure resulting in multiple functions. Upon agonist stimulation endothelial cells secrete VWF multimers from Weibel-Palade bodies into the blood stream where VWF plays an essential role in platelet-dependent primary hemostasis. Elongation of VWF strings on the cells' surface leads to accessibility of VWF binding sites for proteins, such as platelet membrane glycoprotein Ib. The prothrombotic strings are size-regulated by the metalloprotease ADAMTS13 by shear force-activated proteolytic cleavage. VWF string formation was induced by histamine stimulation of HUVEC cells under unidirectional shear flow and VWF strings were detected employing the VWF binding peptide of platelet glycoprotein Ib coupled to latex beads. VWF strings were then used as substrate for kinetic studies of recombinant and plasma ADAMTS13. To investigate specific aspects of the shear-dependent functions of VWF and ADAMTS13, we developed a shear flow assay that allows observation of VWF string formation and their degradation by ADAMTS13 without the need for isolated platelets. Our assay specifically detects VWF strings, can be coupled with fluorescent applications and allows semi-automated, quantitative assessment of recombinant and plasma ADAMTS13 activity. Our assay may serve as a valuable research tool to investigate the biochemical characteristics of VWF and ADAMTS13 under shear flow and could complement diagnostics of von Willebrand Disease and Thrombotic Thrombocytopenic Purpura as it allows detection of shear flow-dependent dysfunction of VWD-associated VWF mutants as well as TTP-associated ADAMTS13 mutants. Copyright © 2014 Elsevier Ltd. All rights reserved.

Dr. Wernher Von Braun Memorial Dinner

NASA Image and Video Library

2017-10-26

The annual Dr. Wernher Von Braun Memorial Dinner was held at the U.S. Space and Rocket Center's Davidson Center on October 26, 2017 with Keynote speaker General John Hyten, Commander of U.S. Strategic Command. Emcee was Mark Larson of Mark Larson Media Services, Inc. Dr. Wernher Von Braun Memorial Scholarships were presented to 8 college students by the National Space Club. Educator of the Year was awarded to Tammy Thorpe; Community Service award was presented to Huntsville, Al. Mayor Tommy Battle. The Communications Award was presented to retired astronaut Dr. Mike Massimino. The Distinguished Science Award was presented to Dr. Martin Weisskopf. The Astronautics Engineer Award was presented to Douglas R. Cooke. The Dr. Wernher Von Braun Space Flight Trophy was presented to Robert Lightfoot.

Wernher von Braun

NASA Image and Video Library

1967-08-28

Marshall Space Flight Center’s (MSFC) director, Dr. Wernher von Braun (right), inspects a component of a laser experiment being conducted in MSFC’s Space Sciences Laboratory during a tour on August 28, 1967.

Wernher von Braun

NASA Image and Video Library

1962-09-11

Marshall Space Flight Center Director Dr. Wernher von Braun explains a detail from a Saturn IB mockup and engine to President John F. Kennedy, Vice President Lyndon Johnson and other guests, September 11, 1962.

Early intraoperative blood collection does not affect complete blood counts, von Willebrand factor or factor VIII levels in normal children.

PubMed

Darwish, Hanni; Mundell, Gillianne; Engen, Dale; Lillicrap, David; Silva, Mariana; James, Paula

2011-01-01

Obtaining blood from children for research studies can be difficult, particularly for controls. One solution is to obtain samples during elective surgery; however, consideration must be given to the potential effects of the timing of phlebotomy. Ten children were recruited and phlebotomy was carried out during a preoperative clinic visit and intraoperatively immediately after the induction of anesthesia but before the start of surgery. CBCs, VWF, and FVIII levels were measured at both time points and no significant differences were seen. This negative result may be beneficial to pediatric research by suggesting that early intraoperative blood collection for controls does not affect the results.

Bewertung von Fahrzeuggeräuschen

NASA Astrophysics Data System (ADS)

Genuit, Klaus; Schulte-Fortkamp, Brigitte; Fiebig, André; Haverkamp, Michael

Bei der Wahrnehmung und Beurteilung eines Automobils sind unzählige Merkmale und Eigenschaften von Bedeutung. Dabei können Merkmale objektiv-technisch beschrieben werden, wie Angaben zur Motorisierung, Höchstgeschwindigkeit, Drehmoment, zulässige Zuladung, Verbrauch usw. Daneben sind weitere Eigenschaften von Bedeutung, die sich einer einfachen objektiv-technischen Beschreibung entziehen. Hier sind Begriffe zu nennen, wie Sicherheit, allgemeine Qualitätsanmutung, Design, Ergonomie, Komfort, Haptik, Fahrdynamik, Zuverlässigkeit, die deutlich schwieriger objektiv erfassbar und beschreibbar sind (Abb. 4.1).

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.

Wernher von Braun

NASA Image and Video Library

1962-01-01

Dr. Wernher von Braun, Director of the Marshall Space Flight Center (MSFC), during his tour of the Space information Division of North American Aviation (NAA) in Downey, California, where the Saturn SII stage was developed.

Wernher von Braun

NASA Image and Video Library

1964-10-14

This photograph, dated October 14, 1964, was taken at the Marned Spacecraft Center, now the Johnson Space Center in Houston, Texas. Dr. von Braun is shown looking over consoles in the Manned Spaceflight Control Center.

Wernher von Braun

NASA Image and Video Library

1959-03-03

Dr. von Braun, Director of the Development Operations Divisons, and Dr. Debus, Director of the Missile Firing Laboratory; Army Ballistic Missile Agency (ABMA), in the blockhouse during the launch of the Pioneer IV, March 3, 1959.

ADAMTS13 activity as a novel risk factor for incident type 2 diabetes mellitus: a population-based cohort study.

PubMed

de Vries, Paul S; van Herpt, Thijs T W; Ligthart, Symen; Hofman, Albert; Ikram, M Arfan; van Hoek, Mandy; Sijbrands, Eric J G; Franco, Oscar H; de Maat, Moniek P M; Leebeek, Frank W G; Dehghan, Abbas

2017-02-01

ADAMTS13 is a protease that breaks down von Willebrand factor (VWF) multimers into smaller, less active particles. VWF has been associated with an increased risk of incident type 2 diabetes mellitus. Here, we determine whether ADAMTS13 activity and VWF antigen are associated with incident diabetes. This study included 5176 participants from the Rotterdam Study, a prospective population-based cohort study. Participants were free of diabetes at baseline and followed up for more than 20 years. Cox proportional hazards models were used to examine the association of ADAMTS13 activity and VWF antigen with incident diabetes. ADAMTS13 activity was associated with an increased risk of incident diabetes (HR 1.17 [95% CI 1.08, 1.27]) after adjustment for known risk factors and VWF antigen levels. Although ADAMTS13 activity was positively associated with fasting glucose and insulin, the association with incident diabetes did not change when we adjusted for these covariates. ADAMTS13 activity was also associated with incident prediabetes (defined on the basis of both fasting and non-fasting blood glucose) after adjustment for known risk factors (HR 1.11 [95% CI 1.03, 1.19]), while the VWF antigen level was not. VWF antigen was associated with incident diabetes, but this association was attenuated after adjustment for known risk factors. ADAMTS13 activity appears to be an independent risk factor for incident prediabetes and type 2 diabetes. As the association between ADAMTS13 and diabetes did not appear to be explained by its cleavage of VWF, ADAMTS13 may have an independent role in the development of diabetes.

Relative Risks of Thrombosis and Bleeding in Different ABO Blood Groups.

PubMed

Franchini, Massimo; Lippi, Giuseppe

2016-03-01

The ABO blood group system is composed of complex carbohydrate molecules (i.e., the A, B, and H determinants) that are widely expressed on the surface of red blood cells and in a variety of other cell and tissues. Along with their pivotal role in transfusion and transplantation medicine, the ABO antigens participate in many other physiological processes and, in particular, are important determinants of von Willebrand factor and factor VIII circulating plasma levels. The precise influence of the ABO system on hemostasis has led the way to the investigation of a putative implication in the risk of developing cardiovascular disorders. Along with the underlying molecular mechanisms, the current knowledge on the role of ABO blood group antigens in both the thrombotic and hemorrhagic risk will be summarized in this narrative review. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

The story of a unique molecule in hemophilia A: recombinant single-chain factor VIII.

PubMed

Pabinger-Fasching, Ingrid

2016-05-01

For patients with hemophilia A, replacement of deficient factor VIII (FVIII) using plasma-derived or recombinant FVIII (rFVIII) products to restore hemostatic control can reduce bleeding complications and preserve musculoskeletal function. Despite the clinical availability of several of these products, challenges remain in the treatment of hemophilia A, the most notable of which are the risk of inhibitor development and the limited half-life of existing FVIII concentrates, which can make prophylaxis burdensome for patients. The use of recombinant protein technology may lead to novel FVIII products with improved properties. This article describes the story of a unique recombinant FVIII protein, rVIII-SingleChain, which is currently in development. In contrast to native FVIII and other commercially available rFVIII preparations, rVIII-SingleChain uses a strong, covalent bond to connect the light and heavy chains, thereby creating a stable, single-chain rFVIII. It has enhanced intrinsic stability, better integrity after reconstitution, and a higher binding affinity to von Willebrand factor. The physicochemical profile of rVIII-SingleChain and preclinical data on its activity and phamacokinetics strengthened the rationale for its clinical investigation. Available data from the AFFINITY clinical trial program are promising; indicating that it has good hemostatic efficacy when used on demand, for prophylaxis, and in the surgical setting, and is also very well tolerated. A pediatric study and an extension study are ongoing as part of the AFFINITY program. © 2016 Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Wernher von Braun

NASA Image and Video Library

1960-11-03

Marshall Space Flight Center’s (MSFC) Director, Dr. Wernher von Braun, is pictured here with Army Ballistic Missile Agency’s (ABMA) Commanding General, J.B. Medaris, before a display of Army missles at the ABMA test lab.

Combination of three angiogenic growth factors has synergistic effects on sprouting of endothelial cell/mesenchymal stem cell-based spheroids in a 3D matrix.

PubMed

Kim, Sook Kyoung; Lee, Jaeyeon; Song, Myeongjin; Kim, Mirim; Hwang, Soon Jung; Jang, Hwanseok; Park, Yongdoo

2016-11-01

Combinations of angiogenic growth factors have been shown to have synergistic effects on angiogenesis and natural wound healing in various animal models. Each growth factor has unique roles during angiogenesis; vascular endothelial growth factor (VEGF) plays a key role during the initial step of angiogenesis, whereas PDGF functions in the maturation of blood vessels. We used a combination of three angiogenic growth factors to increase angiogenesis in vitro and in vivo. We chose VEGF as a basic factor and added platelet-derived growth factor (PDGF) and fibroblast growth factor (FGF) to induce angiogenesis in three in vitro and in vivo models: 3D angiogenesis assay, 3D co-culture, and matrigel plug implantation assay. Cell proliferation was significantly higher in co-cultured cells treated with PDGF + VEGF + FGF than in the control, single, or dual combination groups. mRNA expression of α-smooth muscle actin (α-SMA), von Willebrand factor (vWF), and CD105 was higher in the triple group (PDGF + VEGF + FGF) than in control, single, or dual combination groups. In the PDGF + VEGF + FGF group, the length and number of branches of spheroids was also significantly higher than in the control, single, or dual combination groups. Furthermore, in a nude mouse model, α-SMA expression was significantly higher in the PDGF + VEGF + FGF group than in other groups. In conclusion, the addition of PDGF and FGF to VEGF showed synergistic effects on angiogenesis in vitro and in vivo. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1535-1543, 2016. © 2015 Wiley Periodicals, Inc.

Platelet receptors as therapeutic targets: Past, present and future.

PubMed

Jamasbi, Janina; Ayabe, Keng; Goto, Shinya; Nieswandt, Bernhard; Peter, Karlheinz; Siess, Wolfgang

2017-06-28

Anti-platelet drugs reduce arterial thrombosis after plaque rupture and erosion, prevent stent thrombosis and are used to prevent and treat myocardial infarction and ischaemic stroke. Some of them may also be helpful in treating less frequent diseases such as thrombotic thrombocytopenic purpura. The present concise review aims to cover current and future developments of anti-platelet drugs interfering with the interaction of von Willebrand factor (VWF) with glycoprotein (GP) Ibα, and directed against GPVI, GPIIb/IIIa (integrin α IIb β 3 ), the thrombin receptor PAR-1, and the ADP receptor P2Y 12 . The high expectations of having novel antiplatelet drugs which selectively inhibit arterial thrombosis without interfering with normal haemostasis could possibly be met in the near future.

Isolation and Characterization of Rat Pituitary Endothelial Cells

PubMed Central

Chaturvedi, Kirti; Sarkar, Dipak K.

2010-01-01

Most previous studies that determined the effect of estradiol on angiogenesis used endothelial cells from nonpituitary sources. Because pituitary tumor tissue receives its blood supply via portal and arterial circulation, it is important to use pituitary-derived endothelial cells in studying pituitary angiogenesis. We have developed a magnetic separation technique to isolate endothelial cells from pituitary tissues and have characterized these cells in primary cultures. Endothelial cells of the pituitary showed the existence of endothelial cell marker, CD31, and of von Willebrand factor protein. These cells in cultures also showed immunore-activity of estrogen receptors alpha and beta. The angiogenic factors, vascular endothelial growth factor and basic fibroblast growth factor, significantly increased proliferation and migration of the pituitary-derived endothelial cells in primary cultures. These results suggest that a magnetic separation technique can be used for enrichment of pituitary-derived endothelial cells for determination of cellular mechanisms governing the vascularization in the pituitary. PMID:17028416

Traumatic Hemothorax Blood Contains Elevated Levels of Microparticles that are Prothrombotic but Inhibit Platelet Aggregation.

PubMed

Mitchell, Thomas A; Herzig, Maryanne C; Fedyk, Chriselda G; Salhanick, Marc A; Henderson, Aaron T; Parida, Bijaya K; Prat, Nicolas J; Dent, Daniel L; Schwacha, Martin G; Cap, Andrew P

2017-06-01

Autotransfusion of shed blood from traumatic hemothorax is an attractive option for resuscitation of trauma patients in austere environments. However, previous analyses revealed that shed hemothorax (HX) blood is defibrinated, thrombocytopenic, and contains elevated levels of D-dimer. Mixing studies with normal pooled plasma demonstrated hypercoagulability, evoking concern for potentiation of acute traumatic coagulopathy. We hypothesized that induction of coagulopathic changes by shed HX blood may be due to increases in cellular microparticles (MP) and that these may also affect recipient platelet function. Shed HX blood was obtained from 17 adult trauma patients under an Institutional Review Board approved prospective observational protocol. Blood samples were collected every hour up to 4 h after thoracostomy tube placement. The corresponding plasma was isolated and frozen for analysis. The effects of shed HX frozen plasma (HFP) and isolated HX microparticles (HMP) on coagulation and platelet function were assessed through mixing studies with platelet-rich plasma at various dilutions followed by analysis with thromboelastometry (ROTEM), platelet aggregometry (Multiplate), enzyme-linked immunosorbent assays, and flow cytometry. Furthermore, HFP was assessed for von Willebrand factor antigen levels and multimer content, and plasma-free hemoglobin. ROTEM analysis demonstrated that diluted HFP and isolated HMP samples decreased clotting time, clotting formation time, and increased α angle, irrespective of sample concentrations, when compared with diluted control plasma. Isolated HMP inhibited platelet aggregation in response to adenosine diphosphate, arachidonic acid, and collagen. HFP contained elevated levels of fibrin-degradation products and tissue factor compared with control fresh frozen plasma samples. MP concentrations in HFP were significantly increased and enriched in events positive for phosphatidylserine, tissue factor, CD235, CD45, CD41a, and CD14. von

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.

Wernher von Braun

NASA Image and Video Library

1959-01-01

Marshall Space Flight Center Director Wernher von Braun presents General J.B. Medaris with a new golf bag. General Medaris, (left) was a Commander of the Army Ballistic Missile Agency (ABMA) in Redstone Arsenal, Alabama during 1955 to 1958.

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.

Wernher von Braun

NASA Image and Video Library

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.

Wernher von Braun

NASA Image and Video Library

1959-01-01

In this picture, Dr. Wernher von Braun, who was serving as Director of the Army Ballistic Missile Agency's (ABMA) Development Operations Division, is shown posed with his Mercedes 220SE automobile in front of Redstone Building 4488, which houses the ABMA.

Von Neumann was not a Quantum Bayesian.

PubMed

Stacey, Blake C

2016-05-28

Wikipedia has claimed for over 3 years now that John von Neumann was the 'first quantum Bayesian'. In context, this reads as stating that von Neumann inaugurated QBism, the approach to quantum theory promoted by Fuchs, Mermin and Schack. This essay explores how such a claim is, historically speaking, unsupported. © 2016 The Author(s).

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

Relative value of inflammatory, hemostatic, and rheological factors for incident myocardial infarction and stroke: the Edinburgh Artery Study.

PubMed

Tzoulaki, Ioanna; Murray, Gordon D; Lee, Amanda J; Rumley, Ann; Lowe, Gordon D O; Fowkes, F Gerald R

2007-04-24

The aim of our present study was to compare the association of a wide range of 17 biomarkers of inflammation, hemostasis, and blood rheology with incident heart disease and stroke after accounting for an indicator of subclinical atherosclerotic disease and traditional risk factors and also to determine their incremental predictive ability. We used data from the Edinburgh Artery Study, a population cohort study started in 1987 that comprised 1592 men and women aged 55 to 74 years. Subjects were followed for a mean of 17 years, and 416 of them suffered at least 1 cardiovascular event. In analyses adjusted for cardiovascular risk factors and history of cardiovascular disease (CVD): C-reactive protein, interleukin-6, fibrinogen, fibrin D-dimer, tissue plasminogen activator (t-PA), leukocyte elastase, and lipoprotein(a) (all P<0.01), as well as von Willebrand factor and plasma viscosity (both P<0.05), had significant hazard ratios for incident CVD. Further adjustment for a measure of subclinical atherosclerosis (ankle brachial index) had little impact on these associations. The hazard ratios (95% CI) for incident CVD between top and bottom tertiles in the latter analysis were 1.78 (1.30 to 2.45) for C-reactive protein, 1.85 (1.33 to 2.58) for interleukin-6, and 1.76 (1.35 to 2.31) for fibrinogen. Single biomarkers provided little additional discrimination of incident CVD to that obtained from cardiovascular risk factors and the ankle brachial index. An incremental score of multiple markers [interleukin-6, t-PA, intercellular adhesion molecule 1, and lipoprotein(a)] provided some added discrimination. Several "novel" risk factors predicted CVD after adjustments for conventional risk factors and also for a measure of asymptomatic disease. However, their incremental predictive ability was modest and their clinical utility remains uncertain.

Association of Serum Sex Hormones with Hemostatic Factors in Women On and Off Hormone Therapy: The Multiethnic Study of Atherosclerosis.

PubMed

Williams, Marlene S; Cushman, Mary; Ouyang, Pamela; Heckbert, Susan R; Kalyani, Rita Rastogi; Vaidya, Dhanajay

2016-02-01

Hormone therapy (HT) is associated with increased risk of both venous and arterial thrombosis, which are multifactorial in origin. Our objectives were twofold: first, we sought to examine associations between endogenous serum sex hormone levels and biomarkers of thrombosis and/or coagulation in postmenopausal hormone nonusers. Second, we separately studied the associations between serum sex hormone levels and biomarkers of thrombosis and/or coagulation in postmenopausal hormone users considering the fact that pattern of circulating hormones is different in women taking exogenous hormones. We performed a cross-sectional analysis of postmenopausal women enrolled in a large multiethnic community-based cohort study, The Multiethnic Study of Atherosclerosis. We hypothesized that higher levels of estrogen-related sex hormones would be associated with biomarkers of thrombosis, suggesting mechanisms for differences in thrombotic risk from HT. Women (n = 2878) were included if they were postmenopausal and had thrombotic biomarkers (homocysteine, fibrinogen, C-reactive protein [CRP], factor VIII, and d-dimer) and sex hormone levels (total testosterone [T], bioavailable testosterone, sex hormone binding globulin [SHBG], estradiol [E2], and dehydroepiandrosterone [DHEA]) measured. A smaller random sample of 491 women also had von Willebrand factor (vWF), plasminogen activator inhibitor (PAI-1), and tissue factor pathway inhibitor (TFPI) levels measured. We found that elevated levels of estradiol and SHBG in HT users were associated with elevated levels of CRP and lower levels of TFPI, both of which may be related to a prothrombotic milieu in HT users. HT nonusers had far more prothrombotic associations between elevated serum sex hormone levels and thrombotic biomarkers when compared with HT users.

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

Nonlocal modeling and buckling features of cracked nanobeams with von Karman nonlinearity

NASA Astrophysics Data System (ADS)

Akbarzadeh Khorshidi, Majid; Shaat, Mohamed; Abdelkefi, Abdessattar; Shariati, Mahmoud

2017-01-01

Buckling and postbuckling behaviors of cracked nanobeams made of single-crystalline nanomaterials are investigated. The nonlocal elasticity theory is used to model the nonlocal interatomic effects on the beam's performance accounting for the beam's axial stretching via von Karman nonlinear theory. The crack is then represented as torsional spring where the crack severity factor is derived accounting for the nonlocal features of the beam. By converting the beam into an equivalent infinite long plate with an edge crack subjected to a tensile stress at the far field, the crack energy release rate, intensity factor, and severity factor are derived according to the nonlocal elasticity theory. An analytical solution for the buckling and the postbuckling responses of cracked nonlocal nanobeams accounting for the beam axial stretching according to von Karman nonlinear theory of kinematics is derived. The impacts of the nonlocal parameter on the critical buckling loads and the static nonlinear postbuckling responses of cracked nonlocal nanobeams are studied. The results indicate that the buckling and postbuckling behaviors of cracked nanobeams are strongly affected by the crack location, crack depth, nonlocal parameter, and length-to-thickness ratio.

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.

Prevalence of nucleic acid sequences specific for human parvoviruses, hepatitis A and hepatitis E viruses in coagulation factor concentrates.

PubMed

Modrow, S; Wenzel, J J; Schimanski, S; Schwarzbeck, J; Rothe, U; Oldenburg, J; Jilg, W; Eis-Hübinger, A M

2011-05-01

Due to their high resistance to inactivation procedures, nonenveloped viruses such as parvovirus B19, human bocavirus (HBoV), human parvovirus 4 (PARV4), hepatitis A (HAV) and hepatitis E virus (HEV) pose a particular threat to blood products. Virus transmission to patients treated with blood products presents an additional burden to disease. We determined the frequency and the amount of nucleic acid specific for nonenveloped viruses in recently manufactured preparations of commercial coagulation factor concentrates. At least three different batches of each of 13 different plasma-derived and recombinant coagulation factor products were tested for the presence and the amount of nucleic acid for parvovirus B19, HBoV, human parvovirus 4, hepatitis A virus and HEV by using quantitative polymerase chain reaction. Whereas none of the recombinant products tested positive for any of these viruses, parvovirus B19 DNA with amounts ranging between 2×10(1) and 1.3×10(3) genome equivalents/ml was detected in five plasma-derived products. In addition to parvovirus B19 genotype 1, genotypes 2 and 3 were observed in two batches of a factor VIII/von-Willebrand factor product. In two products (one factor VIII concentrate and one activated prothrombin complex concentrate), a combination of both genotypes 1 and 2 of parvovirus B19 was detected. The data show that nucleic acids from several relevant nonenveloped viruses are not found at detectable levels in coagulation factor concentrates. In some cases, parvovirus B19 DNA was detectable at low levels. Testing of the plasma pools for the full range of parvovirus genotypes is advocated for ensuring product safety. © 2010 The Author(s). Vox Sanguinis © 2010 International Society of Blood Transfusion.

Color constancy: enhancing von Kries adaption via sensor transformations

NASA Astrophysics Data System (ADS)

Finlayson, Graham D.; Drew, Mark S.; Funt, Brian V.

1993-09-01

Von Kries adaptation has long been considered a reasonable vehicle for color constancy. Since the color constancy performance attainable via the von Kries rule strongly depends on the spectral response characteristics of the human cones, we consider the possibility of enhancing von Kries performance by constructing new `sensors' as linear combinations of the fixed cone sensitivity functions. We show that if surface reflectances are well-modeled by 3 basis functions and illuminants by 2 basis functions then there exists a set of new sensors for which von Kries adaptation can yield perfect color constancy. These new sensors can (like the cones) be described as long-, medium-, and short-wave sensitive; however, both the new long- and medium-wave sensors have sharpened sensitivities -- their support is more concentrated. The new short-wave sensor remains relatively unchanged. A similar sharpening of cone sensitivities has previously been observed in test and field spectral sensitivities measured for the human eye. We present simulation results demonstrating improved von Kries performance using the new sensors even when the restrictions on the illumination and reflectance are relaxed.

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.

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.

Alexander von Humboldt and the concept of animal electricity.

PubMed

Kettenmann, H

1997-06-01

More than two hundred years ago, Alexander von Humboldt helped to establish Galvani's view that muscle and nerve tissue are electrically excitable. His 1797 publication was a landmark for establishing the concept of animal electricity. Almost half a century later, von Humboldt became the mentor of the young du Bois-Reymond. With the help of von Humboldt's promotion, du Bois-Reymond demonstrated convincingly that animal tissue has the intrinsic capacity to generate electrical activity, and thus laid the ground for modern electrophysiology.

Identification of the cellular receptor for anthrax toxin

NASA Astrophysics Data System (ADS)

Bradley, Kenneth A.; Mogridge, Jeremy; Mourez, Michael; Collier, R. John; Young, John A. T.

2001-11-01

The tripartite toxin secreted by Bacillus anthracis, the causative agent of anthrax, helps the bacterium evade the immune system and can kill the host during a systemic infection. Two components of the toxin enzymatically modify substrates within the cytosol of mammalian cells: oedema factor (OF) is an adenylate cyclase that impairs host defences through a variety of mechanisms including inhibiting phagocytosis; lethal factor (LF) is a zinc-dependent protease that cleaves mitogen-activated protein kinase kinase and causes lysis of macrophages. Protective antigen (PA), the third component, binds to a cellular receptor and mediates delivery of the enzymatic components to the cytosol. Here we describe the cloning of the human PA receptor using a genetic complementation approach. The receptor, termed ATR (anthrax toxin receptor), is a type I membrane protein with an extracellular von Willebrand factor A domain that binds directly to PA. In addition, a soluble version of this domain can protect cells from the action of the toxin.

Dr. von Braun With German Rocket Experimenters

NASA Technical Reports Server (NTRS)

1930-01-01

Dr. von Braun was among a famous group of rocket experimenters in Germany in the 1930s. This photograph is believed to be made on the occasion of Herman Oberth's Kegelduese liquid rocket engine being certified as to performance during firing. From left to right are R. Nebel, Dr. Ritter, Mr. Baermueller, Kurt Heinish, Herman Oberth, Klaus Riedel, Wernher von Braun, and an unidentified person.

Comparison of In Vitro- and Chorioallantoic Membrane (CAM)-Culture Systems for Cryopreserved Medulla-Contained Human Ovarian Tissue

PubMed Central

Isachenko, Vladimir; Mallmann, Peter; Petrunkina, Anna M.; Rahimi, Gohar; Nawroth, Frank; Hancke, Katharina; Felberbaum, Ricardo; Genze, Felicitas; Damjanoski, Ilija; Isachenko, Evgenia

2012-01-01

At present, there are three ways to determine effectively the quality of the cryopreservation procedure using ovarian tissue before the re-implantation treatment: evaluation of follicles after post-thawing xenotransplantation to SCID mouse, in-vitro culture in a large volume of culture medium under constant agitation and culture on embryonic chorio-allantoic membrane within a hen's eggs. The aim of this study was to compare the two methods, culture in vitro and culture on embryonic chorioallantoic membrane (CAM) of cryopreserved human ovarian medulla-contained and medulla-free cortex. Ovarian fragments were divided into small pieces (1.5–2.0×1.0–1.2×0.8–1.5) of two types, cortex with medulla and medulla-free cortex, frozen, thawed and randomly divided into the following four groups. Group 1: medulla-free cortex cultured in vitro for 8 days in large volume of medium with mechanical agitation, Group 2: medulla-containing cortex cultured in vitro, Group 3: medulla-free cortex cultured in CAM-system for 5 days, Group 4: medulla-containing cortex cultured in CAM-system. The efficacy of the tissue culture was evaluated by the development of follicles and by intensiveness of angiogenesis in the tissue (von Willebrand factor and Desmin). For Group 1, 2, 3 and 4, respectively 85%, 85%, 87% and 84% of the follicles were morphologically normal (P>0.1). The immunohistochemical analysis showed that angiogenesis detected by von Willebrand factor was lower in groups 1 and 3 (medulla-free cortex). Neo-vascularisation (by Desmin) was observed only in ovarian tissue of Group 4 (medulla-contained cortex after CAM-culture). It appears that the presence of medulla in ovarian pieces is beneficial for post-thaw development of cryopreserved human ovarian tissue. For medical practice it is recommended for evaluation of post-warming ovarian tissue to use the CAM-system as a valuable alternative to xenotransplantation and for cryopreservation of these tissues to prepare ovarian

Von Neumann's impossibility proof: Mathematics in the service of rhetorics

NASA Astrophysics Data System (ADS)

Dieks, Dennis

2017-11-01

According to what has become a standard history of quantum mechanics, in 1932 von Neumann persuaded the physics community that hidden variables are impossible as a matter of principle, after which leading proponents of the Copenhagen interpretation put the situation to good use by arguing that the completeness of quantum mechanics was undeniable. This state of affairs lasted, so the story continues, until Bell in 1966 exposed von Neumann's proof as obviously wrong. The realization that von Neumann's proof was fallacious then rehabilitated hidden variables and made serious foundational research possible again. It is often added in recent accounts that von Neumann's error had been spotted almost immediately by Grete Hermann, but that her discovery was of no effect due to the dominant Copenhagen Zeitgeist. We shall attempt to tell a story that is more historically accurate and less ideologically charged. Most importantly, von Neumann never claimed to have shown the impossibility of hidden variables tout court, but argued that hidden-variable theories must possess a structure that deviates fundamentally from that of quantum mechanics. Both Hermann and Bell appear to have missed this point; moreover, both raised unjustified technical objections to the proof. Von Neumann's argument was basically that hidden-variables schemes must violate the ;quantum principle; that physical quantities are to be represented by operators in a Hilbert space. As a consequence, hidden-variables schemes, though possible in principle, necessarily exhibit a certain kind of contextuality. As we shall illustrate, early reactions to Bohm's theory are in agreement with this account. Leading physicists pointed out that Bohm's theory has the strange feature that pre-existing particle properties do not generally reveal themselves in measurements, in accordance with von Neumann's result. They did not conclude that the ;impossible was done; and that von Neumann had been shown wrong.

Wernher von Braun

NASA Image and Video Library

1964-10-14

This photograph is dated October 14, 1964, and shows Dr. von Braun, left, during a tour of the NASA Marned Spacecraft Center, now the Johnson Space Center. He is with Dr. J.P. Kuettner, center, from the Marshall Space Flight Center, and Warren J. North from the Manned Spacecraft Center.

Dr. von Braun with Seven Original Mercury Astronauts

NASA Technical Reports Server (NTRS)

1959-01-01

In this photo, Dr. Wernher von Braun, Director of the U.S. Army Ballistic Missile Agency's (ABMA) Development Operations Division, is shown briefing the seven original Mercury astronauts in ABMA's Fabrication Laboratory. (Left to right) Guss Grissom, Walter Schirra, Alan Shepard, John Glenn, Scott Carpenter, Gordon Cooper, Donald Slayton, and Dr. von Braun.

Ein Konzept für den energieeffizienten Betrieb von Mobilfunknetzen

NASA Astrophysics Data System (ADS)

Bayer, N.; von Hugo, D.

2015-11-01

Der flächendeckende Betrieb mehrerer Mobilfunknetze unterschiedlicher Technologie in einem Land sorgt aufgrund der ständigen Bereithaltung von Übertragungskapazität für Dienste mit zunehmend höherem Datenvolumenbedarf für einen erheblichen Energieverbrauch. Das Forschungsförderungsprojekt ComGreen hat sich zur Aufgabe gesetzt, durch lastadaptiven Betrieb und intelligente dynamische Rekonfiguration des Funkzugangsnetzes zur Energieeinsparung beizutragen. Konzept, Herausforderungen, ausgewählte Ergebnisse von Simulationen und prototypischem Betrieb werden ebenso wie typische Erwartungswerte des künftigen Energieverbrauchs im Mobilfunkbereich vorgestellt. Sowohl Berechnungen als auch Messungen zeigen, dass durch kontext-basierte dynamische Rekonfiguration von zellularen Funknetzen Energieeinsparungen im Bereich von 25-40 % ermöglicht werden.

Abnormal factor VIII coagulant antigen in patients with renal dysfunction and in those with disseminated intravascular coagulation.

PubMed Central

Weinstein, M J; Chute, L E; Schmitt, G W; Hamburger, R H; Bauer, K A; Troll, J H; Janson, P; Deykin, D

1985-01-01

Factor VIII antigen (VIII:CAg) exhibits molecular weight heterogeneity in normal plasma. We have compared the relative quantities of VIII:CAg forms present in normal individuals (n = 22) with VIII:CAg forms in renal dysfunction patients (n = 19) and in patients with disseminated intravascular coagulation (DIC; n = 7). In normal plasma, the predominant VIII: CAg form, detectable by sodium dodecyl sulfate polyacrylamide gel electrophoresis, was of molecular weight 2.4 X 10(5), with minor forms ranging from 8 X 10(4) to 2.6 X 10(5) D. A high proportion of VIII:CAg in renal dysfunction patients, in contrast, was of 1 X 10(5) mol wt. The patients' high 1 X 10(5) mol wt VIII: CAg level correlated with increased concentrations of serum creatinine, F1+2 (a polypeptide released upon prothrombin activation), and with von Willebrand factor. Despite the high proportion of the 1 X 10(5) mol wt VIII:CAg form, which suggests VIII:CAg proteolysis, the ratio of Factor VIII coagulant activity to total VIII:CAg concentration was normal in renal dysfunction patients. These results could be simulated in vitro by thrombin treatment of normal plasma, which yielded similar VIII:CAg gel patterns and Factor VIII coagulant activity to antigen ratios. DIC patients with high F1+2 levels but no evidence of renal dysfunction had an VIII:CAg gel pattern distinct from renal dysfunction patients. DIC patients had elevated concentrations of both the 1 X 10(5) and 8 X 10(4) mol wt VIII:CAg forms. We conclude that an increase in a particular VIII:CAg form correlates with the severity of renal dysfunction. The antigen abnormality may be the result of VIII:CAg proteolysis by a thrombinlike enzyme and/or prolonged retention of proteolyzed VIII:CAg fragments. Images PMID:3932466

EGF and hydrocortisone as critical factors for the co-culture of adipogenic differentiated ASCs and endothelial cells.

PubMed

Volz, Ann-Cathrin; Huber, Birgit; Schwandt, Alina Maria; Kluger, Petra Juliane

In vitro composed vascularized adipose tissue is and will continue to be in great demand e.g. for the treatment of extensive high-graded burns or the replacement of tissue after tumor removal. Up to date, the lack of adequate culture conditions, mainly a culture medium, decelerates further achievements. In our study, we evaluated the influence of epidermal growth factor (EGF) and hydrocortisone (HC), often supplemented in endothelial cell (EC) specific media, on the co-culture of adipogenic differentiated adipose-derived stem cells (ASCs) and microvascular endothelial cells (mvECs). In ASCs, EGF and HC are thought to inhibit adipogenic differentiation and have lipolytic activities. Our results showed that in indirect co-culture for 14 days, adipogenic differentiated ASCs further incorporated lipids and partly gained an univacuolar morphology when kept in media with low levels of EGF and HC. In media with high EGF and HC levels, cells did not incorporate further lipids, on the contrary, cells without lipid droplets appeared. Glycerol release, to measure lipolysis, also increased with elevated amounts of EGF and HC in the culture medium. Adipogenic differentiated ASCs were able to release leptin in all setups. MvECs were functional and expressed the cell specific markers, CD31 and von Willebrand factor (vWF), independent of the EGF and HC content as long as further EC specific factors were present. Taken together, our study demonstrates that adipogenic differentiated ASCs can be successfully co-cultured with mvECs in a culture medium containing low or no amounts of EGF and HC, as long as further endothelial cell and adipocyte specific factors are available. Copyright © 2017 International Society of Differentiation. Published by Elsevier B.V. All rights reserved.

Hemorrhoids screening and treatment prior to LVAD: is it a necessity?

PubMed

Skouri, Hadi; Shurrab, Mohammed; Zahnan, Jad; Deeba, Samer; Sfeir, Pierre; Gharzuddin, Walid; Haj-Yahia, Saleem

2016-04-12

Continuous-flow left ventricle assist devices (CF-LVADs) has become an essential modality in the management of stage D heart failure (HF) with significant improvement in survival and quality of life. Due to the durability of such devices and long term support complications such as bleeding and aortic insufficiency has emerged. Bleeding accounts for more than 20 % with the majority being from the gastrointestinal tract. The increase of bleeding tendency are mainly attributed to the loss of large von Willebrand's Factor (vWF) multimers due to shear stress with the chronic intake of anticoagulants. We are reporting two cases of patients with Stage D HF and history of hemorrhoids presenting for LVAD implantation. Many efforts that decrease bleeding related to CF-LVADs will be discussed with focus on hemorrhoids.

Infantile hemangioma-like vascular lesion in a 26-year-old woman after abortion.

PubMed

Lu, Yang; Wang, Shu Jun; Li, Xin; Hu, Li; Zhang, Wen Jie; Li, Wei

2014-01-01

A 26-year-old woman (G2P1A1) presented with a 5-week history of multiple red marks on her body after a therapeutic abortion. A physical examination found 15 palpable red marks on her head, neck, chest, arms and legs. Proliferating endothelial cells, which expressed CD31, CD34, von Willebrand factor, but not Glut-1 and merosin, were observed in the lesional area by histopathological analyses. Histocompatibility antigen typing of 2 lesions was identical to a sample from peripheral blood. Accelerated regression was observed in 2 lesions treated by intralesional injection of betamethasone, while spontaneous regression was observed within 9 months in the remaining lesions without any treatment. Rapid growth, spontaneous regression and histological analyses in this case support the diagnosis of 'infantile hemangioma-like vascular lesion'.

Nucleation of platelets with bloodborne pathogens on Kupffer cell precedes other innate immunity and contributes to bacterial clearance

PubMed Central

Wong, Connie H. Y.; Jenne, Craig N.; Petri, Björn; Chrobok, Navina L.; Kubes, Paul

2016-01-01

Using intravital imaging of the liver, we unveil a collaborative role for platelets with Kupffer cells (KCs) in eradicating bloodborne bacterial infections. Under basal conditions, platelets via glycoprotein Ib (GPIb) formed transient “touch-and-go” interactions with von Willebrand factor (vWF) constitutively expressed on KCs. Bacteria, such as Bacillus cereus and Methicillin-resistant Staphylococcus aureus (MRSA), were rapidly caught by KCs and triggered platelets to switch from “touch-and-go” to sustained GPIIb-mediated adhesion on the KC surface to encase the bacterium. Infected GpIbα−/− mice demonstrated increased endothelial and KC damage, leading to increased fluid leakage, significant polycythemia and rapid mortality. This study identifies a novel surveillance mechanism of intravascular macrophage by platelets that rapidly converts to a critical host response against bloodborne bacteria. PMID:23770641

Wernher von Braun

NASA Image and Video Library

1959-03-04

Dr. Wernher von Braun, Director of the U.S. Army Ballistic Missile Agency's (ABMA) Development Operations Division, talks to Huntsville Mayor R. B. "Speck" Searcy, center, and Army Ordnance Missile Command (ARMC) Major General John B. Medaris, right, during "Moon Day" celebrations in downtown Huntsville, Alabama. (Courtesy of Huntsville/Madison County Public Library)

Wernher von Braun

NASA Image and Video Library

1965-05-25

In this photo, Dr. von Braun anxiously awaits the launch of the Saturn I vehicle (SA-8) in the Launch Complex Control Center at the Kennedy Space Center in Florida on May 25, 1965. The SA-8 mission made the first night launch and deployed the Pegasus II micro meteoroid detection satellite.

Dr. von Braun with Original Mercury Astronauts

NASA Technical Reports Server (NTRS)

1959-01-01

Dr. Wernher von Braun, Director of the Army Ballistic Missile Agency's (ABMA) Development Operations Division, poses with the original Mercury astronauts in ABMA's Fabrication Laboratory during a 1959 visit. Inspecting Mercury-Redstone hardware are from left to right, Alan Shepard, Donald Deke Slayton, Virgil Gus Grissom, von Braun, Gordon Cooper, Wally Schirra, John Glenn, and Scott Carpenter. Project Mercury officially began October 7, 1958 as the United States' first manned space program.

Circulating plasma vascular endothelial growth factor and microvascular complications of type 1 diabetes mellitus: the influence of ACE inhibition.

PubMed

Chaturvedi, N; Fuller, J H; Pokras, F; Rottiers, R; Papazoglou, N; Aiello, L P

2001-04-01

To determine whether circulating plasma vascular endothelial growth factor (VEGF) is elevated in the presence of diabetic microvascular complications, and whether the impact of angiotensin-converting enzyme (ACE) inhibitors on these complications can be accounted for by changes in circulating VEGF. Samples (299/354 of those with retinal photographs) from the EUCLID placebo-controlled clinical trial of the ACE inhibitor lisinopril in mainly normoalbuminuric non-hypertensive Type 1 diabetic patients were used. Albumin excretion rate (AER) was measured 6 monthly. Geometric mean VEGF levels by baseline retinopathy status, change in retinopathy over 2 years, and by treatment with lisinopril were calculated. No significant correlation was observed between VEGF at baseline and age, diabetes duration, glycaemic control, blood pressure, smoking, fibrinogen and von Willebrand factor. Mean VEGF concentration at baseline was 11.5 (95% confidence interval 6.0--27.9) pg/ml in those without retinopathy, 12.9 (6.0--38.9) pg/ml in those with non-proliferative retinopathy, and 16.1 (8.1--33.5) pg/ml in those with proliferative retinopathy (P = 0.06 for trend). Baseline VEGF was 15.2 pg/ml in those who progressed by at least one level of retinopathy by 2 years compared to 11.8 pg/ml in those who did not (P = 0.3). VEGF levels were not altered by lisinopril treatment. Results were similar for AER. Circulating plasma VEGF concentration is not strongly correlated with risk factor status or microvascular disease in Type 1 diabetes, nor is it affected by ACE inhibition. Changes in circulating VEGF cannot account for the beneficial effect of ACE inhibition on retinopathy.

Wernher von Braun

NASA Image and Video Library

1965-04-13

Walt Disney toured the West Test Area during his visit to the Marshall Space Flight Center on April 13, 1965. The three in center foreground are Karl Heimburg, Director, Test Division; Dr. von Braun, Director, MSFC; and Walt Disney. The Dynamic Test Stand with the S-1C stage being installed is in the background.

Wernher von Braun

NASA Image and Video Library

1961-10-19

Dr. Wernher von Braun holds the coveted Hermarn Oberth award presented to him by Professor Oberth during the banquet hosted by the Alabama Section of the American Rocket Society (ARS), on October 19, 1961. The Oberth award was given for outstanding technical contributions to the field of astronautics or for the promotion and advancement of astronautical sciences.

Dr. von Braun With Five of the Original Astronauts

NASA Technical Reports Server (NTRS)

1959-01-01

Five of the seven original astronauts are seen with Dr. von Braun inspecting the Mercury-Redstone hardware in the Fabrication Laboratory of Army Ballistic Missile Agency (ABMA) in 1959. Left to right: Astronauts Walter Schirra, Alan Shepard, John Glenn, Scott Carpenter, Gordon Cooper, and Dr. von Braun.

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.

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.

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.

Storage and regulated secretion of factor VIII in blood outgrowth endothelial cells

PubMed Central

van den Biggelaar, Maartje; Bouwens, Eveline A.M.; Kootstra, Neeltje A.; Hebbel, Robert P.; Voorberg, Jan; Mertens, Koen

2009-01-01

Background Gene therapy provides an attractive alternative for protein replacement therapy in hemophilia A patients. Recent studies have shown the potential benefit of directing factor (F)VIII gene delivery to cells that also express its natural carrier protein von Willebrand factor (VWF). In this study, we explored the feasibility of blood outgrowth endothelial cells as a cellular FVIII delivery device with particular reference to long-term production levels, intracellular storage in Weibel-Palade bodies and agonist-induced regulated secretion. Design and Methods Human blood outgrowth endothelial cells were isolated from peripheral blood collected from healthy donors, transduced at passage 5 using a lentiviral vector encoding human B-domain deleted FVIII-GFP and characterized by flow cytometry and confocal microscopy. Results Blood outgrowth endothelial cells displayed typical endothelial morphology and expressed the endothelial-specific marker VWF. Following transduction with a lentivirus encoding FVIII-GFP, 80% of transduced blood outgrowth endothelial cells expressed FVIII-GFP. Levels of FVIII-GFP positive cells declined slowly upon prolonged culturing. Transduced blood outgrowth endothelial cells expressed 1.6±1.0 pmol/1×106 cells/24h FVIII. Morphological analysis demonstrated that FVIII-GFP was stored in Weibel-Palade bodies together with VWF and P-selectin. FVIII levels were only slightly increased following agonist-induced stimulation, whereas a 6- to 8-fold increase of VWF levels was observed. Subcellular fractionation revealed that 15–22% of FVIII antigen was present within the dense fraction containing Weibel-Palade bodies. Conclusions We conclude that blood outgrowth endothelial cells, by virtue of their ability to store a significant portion of synthesized FVIII-GFP in Weibel-Palade bodies, provide an attractive cellular on-demand delivery device for gene therapy of hemophilia A. PMID:19336741

Eine selbstkonsistente Carleman Linearisierung zur Analyse von Oszillatoren

NASA Astrophysics Data System (ADS)

Weber, Harry; Mathis, Wolfgang

2017-09-01

Die Analyse nichtlinearer dynamischer Schaltungen ist bis heute eine herausfordernde Aufgabe, da nur selten analytische Lösungen angegeben werden können. Daher wurden eine Vielzahl von Methoden entwickelt, um eine qualitative oder quantitative Näherung für die Lösungen der Netzwerkgleichung zu erhalten. Oftmals wird beispielsweise eine Kleinsignalanalyse mit Hilfe einer Taylorreihe in einem Arbeitspunkt durchgeführt, die nach den Gliedern erster Ordnung abgebrochen wird. Allerdings ist diese Linearisierung nur in der Nähe des stabilen Arbeitspunktes für hyperbolische Systeme gültig. Besonders für die Analyse des dynamischen Verhaltens von Oszillatoren treten jedoch nicht-hyperbolische Systeme auf, sodass diese Methode nicht angewendet werden kann Mathis (2000). Carleman hat gezeigt, dass nichtlineare Differentialgleichungen mit polynomiellen Nichtlinearitäten in ein unendliches System von linearen Differentialgleichungen transformiert werden können Carleman (1932). Wird das unendlichdimensionale Gleichungssystem für numerische Zwecke abgebrochen, kann bei Oszillatoren der Übergang in eine stationäre Schwingung (Grenzzyklus) nicht wiedergegeben werden. In diesem Beitrag wird eine selbstkonsistente Carleman Linearisierung zur Untersuchung von Oszillatoren vorgestellt, die auch dann anwendbar ist, wenn die Nichtlinearitäten keinen Polynomen entsprechen. Anstelle einer linearen Näherung um einen Arbeitspunkt, erfolgt mit Hilfe der Carleman Linearisierung eine Approximation auf einem vorgegebenen Gebiet. Da es jedoch mit der selbstkonsistenten Technik nicht möglich ist, das stationäre Verhalten von Oszillatoren zu beschreiben, wird die Berechnung einer Poincaré-Abbildung durchgeführt. Mit dieser ist eine anschließende Analyse des Oszillators möglich.

Monte Carlo turbulence simulation using rational approximations to von Karman spectra

NASA Technical Reports Server (NTRS)

Campbell, C. W.

1986-01-01

Turbulence simulation is computationally much simpler using rational spectra, but turbulence falls off as f exp -5/3 in frequency ranges of interest to aircraft response and as predicted by von Karman's model. Rational approximations to von Karman spectra should satisfy three requirements: (1) the rational spectra should provide a good approximation to the von Karman spectra in the frequency range of interest; (2) for stability, the resulting rational transfer function should have all its poles in the left half-plane; and (3) at high frequencies, the rational spectra must fall off as an integer power of frequency, and since the -2 power is closest to the -5/3 power, the rational approximation should roll off as the -2 power at high frequencies. Rational approximations to von Karman spectra that satisfy these three criteria are presented, along with spectra from simulated turbulence. Agreement between the spectra of the simulated turbulence and von Karman spectra is excellent.

Wernher von Braun

NASA Image and Video Library

1959-01-21

In this photo, (left to right) Army Ballistic Missile Agency (ABMA) Missile Firing Laboratory Chief Dr. Kurt Debus, Director of the ABMA Development Operations Division, Dr. von Braun and an unidentified individual in blockhouse during the CM-21 (Jupiter) firing. The Jupiter missile CM-21 became the first Chrysler production qualification missile to be fired and in March 1959 launched the Pioneer IV.

Von Karman Vortices

NASA Image and Video Library

2017-12-08

July 4th, 2002: Description: As air flows over and around objects in its path, spiraling eddies, known as Von Karman vortices, may form. The vortices in this image were created when prevailing winds sweeping east across the northern Pacific Ocean encountered Alaska’s Aleutian Islands. Source: Landsat 7 To learn more about the Landsat satellite go to: landsat.gsfc.nasa.gov/

Wernher von Braun

NASA Image and Video Library

1954-07-01

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."

Determining the relationship between "microvessel density" and different grades of astrocytoma based on immunohistochemistry for "factor VIII-related antigen" (von Willebrand factor) expression in tumor microvessels.

PubMed

Mahzouni, Parvin; Mohammadizadeh, Fereshteh; Mougouei, Kourosh; Moghaddam, Noushin Afshar; Chehrei, Ali; Mesbah, Alireza

2010-01-01

Astrocytic brain tumors are the most common primary central nervous system tumors, which are classified into four grades. One of the most important pathologic criteria for the diagnosis of higher-grade astrocytomas (especially glioblastoma multiforme) is microvessel proliferation, particularly in the form of glomeruloid complex. Because tumor angiogenesis is a necessary factor for growth and invasiveness of malignancies, microvessel density (MVD) and intensity of angiogenesis may be used to determine the grade of astrocytomas and plan therapy accordingly. We have planned this study to evaluate the relationship between vwf expression in microvessels and different grades of astrocytoma. Sixty-four formalin-fixed and paraffin-embedded blocks of surgical specimens with diagnosis of astrocytoma (grades I to IV, each of them 16 blocks) were selected in a simple-nonrandom sampling. Thin sections of tissue blocks underwent immunohistochemical staining for vwf. The stained slides were examined using a light microscope at low (100) and high (400) magnifications. MVD was estimated by calculating the mean number of stained microvessels in three areas of highest vascularization in the high-power field (400). The intensity of staining was determined based on a 3 scale model, in which scores 0, 1, 2, and 3 mean no detectable stain, trace staining, moderate amount of diffuse stain, and strong diffuse staining, respectively. Thirty-six (56%) patients were male and 28 (44%) were female. Scores 0 and 1 of microvessel staining intensity were not observed in any grades studied, but severe staining intensity (score 3) was observed in 18.8%, 37.5%, 56.3%, and 87.5% of grades I, II, III, and IV astrocytomas, respectively. "Vwf vessel index" (MVD staining intensity of microvessels) was 23.84, 25.62, 31.62, and 62.43 in grades I, II, III, and IV astrocytomas, respectively. We found a significant relationship between staining intensity of vwf in microvessels and different grades of

[Association of age, inflammatory markers and subclinical atherosclerosis in subjects free from cardiovascular disease].

PubMed

Páramo, José A; Orbe, Josune; Beloqui, Oscar; Colina, Inmaculada; Benito, Alberto; Rodríguez, José A; Díez, Javier

2008-09-27

We assessed whether an independent association between inflammatory markers and age-related subclinical atherosclerosis could be found in subjects free from cardiovascular disease. Metabolic parameters, inflammatory and endothelial markers, such as high-sensitivity C-reactive protein, interleukin-6, fibrinogen and von Willebrand factor, as well as the carotid intima-media thickness were assessed in 890 asymptomatic subjects (mean age: 55 years; range: 20-80 years; 80% men) with cardiovascular risk factors. Subjects in the upper quartile (age 61-80 years) showed a significant increase of traditional risk factors, particularly arterial pressure and glucose levels (p < 0.01) as compared with lower quartiles. We also found a significant increase in the levels on inflammatory and endothelial markers (p < 0.001) and intima-media thickness (p < 0.001) in older adults. In the multivarate analysis, after adjustment for cardiovascular risk factors, intima-media thickness was independently associated with inflammation and endothelial dysfunction in older adults (p < 0.01). Besides age, systemic inflammation and vascular damage are associated with subclinical atherosclerosis in asymptomatic subjects. The age-related inflammatory profile may predispose to cardiovascular complications.

A phase I study of ABT-510 plus bevacizumab in advanced solid tumors.

PubMed

Uronis, Hope E; Cushman, Stephanie M; Bendell, Johanna C; Blobe, Gerard C; Morse, Michael A; Nixon, Andrew B; Dellinger, Andrew; Starr, Mark D; Li, Haiyan; Meadows, Kellen; Gockerman, Jon; Pang, Herbert; Hurwitz, Herbert I

2013-06-01

Targeting multiple regulators of tumor angiogenesis have the potential to improve treatment efficacy. Bevacizumab is a monoclonal antibody directed against vascular endothelial growth factor and ABT-510 is a synthetic analog of thrombospondin, an endogenous angiogenesis inhibitor. Dual inhibition may result in additional benefit. We evaluated the safety, tolerability, and efficacy of the combination of bevacizumab plus ABT-510 in patients with refractory solid tumors. We also explored the effects of these agents on plasma-based biomarkers and wound angiogenesis. Thirty-four evaluable subjects were enrolled and received study drug. Therapy was well tolerated; minimal treatment-related grade 3/4 toxicity was observed. One patient treated at dose level 1 had a partial response and five other patients treated at the recommended phase II dose had prolonged stable disease for more than 1 year. Biomarker evaluation revealed increased levels of D-dimer, von Willebrand factor, placental growth factor, and stromal-derived factor 1 in response to treatment with the combination of bevacizumab and ABT-510. Data suggest that continued evaluation of combination antiangiogenesis therapies may be clinically useful.

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.

PT2385 for the Treatment of Von Hippel-Lindau Disease-Associated Clear Cell Renal Cell Carcinoma

ClinicalTrials.gov

2017-08-23

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

Wernher von Braun

NASA Image and Video Library

1963-03-28

Dr. von Braun, Director of the Marshall Space Flight Center (MSFC), and Dr. Debus, Director of the Launch Operations Center, at Complex 34 prior to the Launch of the SA-4 (the fourth flight of Saturn I), March 28, 1963. The mission conducted the second "Project Highwater" experiment, which the upper stage ejected 30,000 gallons of ballast water in the upper atmosphere for a physics experiment.

Wernher von Braun

NASA Image and Video Library

1968-10-01

Dr. von Braun, Director of the Marshall Space Flight Center (MSFC), greets Commander of Apollo 7 mission, Walter M. Schirra, Jr., during the mission briefing at Kennedy Space Center (KSC). The Apollo 7 mission, boosted by a Saturn IB launch vehicle on October 11, 1968, was the first flight of the Apollo spacecraft with crew. Other crew members were Astronaut Donn Eisele and Astronaut Walter Cunningham.

Measurements in Quantum Mechanics and von NEUMANN's Model

NASA Astrophysics Data System (ADS)

Mello, Pier A.; Johansen, Lars M.

2010-12-01

Many textbooks on Quantum Mechanics are not very precise as to the meaning of making a measurement: as a consequence, they frequently make assertions which are not based on a dynamical description of the measurement process. A model proposed by von Neumann allows a dynamical description of measurement in Quantum Mechanics, including the measuring instrument in the formalism. In this article we apply von Neumann's model to illustrate the measurement of an observable by means of a measuring instrument and show how various results, which are sometimens postulated without a dynamical basis, actually emerge. We also investigate the more complex, intriguing and fundamental problem of two successive measurements in Quantum Mechanics, extending von Neumann's model to two measuring instruments. We present a description which allows obtaining, in a unified way, various results that have been given in the literature.

Clinical experience with Optivate®, high-purity factor VIII (FVIII) product with von Willebrand factor (VWF) in young children with haemophilia A.

PubMed

Matysiak, M; Bobrowska, H; Balwierz, W; Chybicka, A; Kowalczyk, J R; Shaikh-Zaidi, R; Gillanders, K; Dash, C H

2011-09-01

Optivate® is a high-purity FVIII/VWF product. Its safety, tolerability and efficacy in subjects ≥ 12 years have been demonstrated. This study was undertaken to assess Optivate® in children with haemophilia A. Twenty-five children, including one PUP (previously untreated patient), aged 1-6 years (mean 4.67 years) were treated with Optivate® for 26 weeks. Inhibitors were assessed every 3 months and viral status at the study start and end. Prophylaxis was used by five boys and on demand by twenty. The mean number of bleeds in the study was lower compared to the same period pre-study (12.0/child vs. 16.2/child), with fewer bleeds (P < 0.05) in the prophylactic subgroup (8.0/child) compared with the on-demand sub-group (13.4/child). Fourteen major bleeds were reported, all by the on-demand sub-group. Children on prophylaxis were administered a mean of 59.4 infusions; on-demand group 35.1 infusions. A total of 998 infusions were used with a mean dose of 29.1 IU kg⁻¹, and a mean of 38.6 exposure days (ED). Children < 4 years used higher doses, and reported fewer bleeds than older children. Children's Parents/Guardians rated Optivate® as helpful or very helpful in controlling 97.5% of bleeds by the prophylactic group, and in 98.5% of the bleeds in the on-demand group. Only 5 of 101 ADRs were treatment-related events (5%), all were mild and non-serious. There were no clinically significant changes in vital signs, viral transmissions or inhibitors. In young children Optivate® was well tolerated, safe and efficacious. © 2011 Blackwell Publishing Ltd.

Test of Von Baer's law of the conservation of early development.

PubMed

Poe, Steven

2006-11-01

One of the oldest and most pervasive ideas in comparative embryology is the perceived evolutionary conservation of early ontogeny relative to late ontogeny. Karl Von Baer first noted the similarity of early ontogeny across taxa, and Ernst Haeckel and Charles Darwin gave evolutionary interpretation to this phenomenon. In spite of a resurgence of interest in comparative embryology and the development of mechanistic explanations for Von Baer's law, the pattern itself has been largely untested. Here, I use statistical phylogenetic approaches to show that Von Baer's law is an unnecessarily complex explanation of the patterns of ontogenetic timing in several clades of vertebrates. Von Baer's law suggests a positive correlation between ontogenetic time and amount of evolutionary change. I compare ranked position in ontogeny to frequency of evolutionary change in rank for developmental events and find that these measures are not correlated, thus failing to support Von Baer's model. An alternative model that postulates that small changes in ontogenetic rank are evolutionarily easier than large changes is tentatively supported.

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.

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.

Vertebral telangiectatic osteosarcoma in a dog.

PubMed

Brellou, G; Papaioannou, N; Patsikas, M; Polizopoulou, Z; Vlemmas, I

2004-01-01

Telangiectatic osteosarcoma (TOS) affecting the seventh cervical vertebra (C7) was diagnosed in a 4-year-old male dog with signs of locomotor dysfunction. Bone lysis and an extradural-extramedullary mass were observed in radiographs and occipital myelograms. The diagnosis was confirmed by histopathologic and immunohistochemical examination of the mass. The tumor was composed of large blood-filled cavities lined by anaplastic stromal cells (malignant osteoblasts). Around the cavities were characteristic tumor giant cells ("bizarre cells"). Immunohistochemically the tumor cells were positive for proliferating cell nuclear antigen. The lining cells of the cysts were negative for von Willebrand factor. The histologic findings in this case of TOS involving C7 were similar to those seen in other cases of TOS in dogs and in people. Immunohistochemistry was a useful tool for assessing malignancy and for ruling out other differential diagnoses.

Mechanical Activation of a Multimeric Adhesive Protein Through Domain Conformational Change

NASA Astrophysics Data System (ADS)

Wijeratne, Sithara S.; Botello, Eric; Yeh, Hui-Chun; Zhou, Zhou; Bergeron, Angela L.; Frey, Eric W.; Patel, Jay M.; Nolasco, Leticia; Turner, Nancy A.; Moake, Joel L.; Dong, Jing-fei; Kiang, Ching-Hwa

2013-03-01

The mechanical force-induced activation of the adhesive protein von Willebrand factor (VWF), which experiences high hydrodynamic forces, is essential in initiating platelet adhesion. The importance of the mechanical force-induced functional change is manifested in the multimeric VWF’s crucial role in blood coagulation, when high fluid shear stress activates plasma VWF (PVWF) multimers to bind platelets. Here, we showed that a pathological level of high shear stress exposure of PVWF multimers results in domain conformational changes, and the subsequent shifts in the unfolding force allow us to use force as a marker to track the dynamic states of the multimeric VWF. We found that shear-activated PVWF multimers are more resistant to mechanical unfolding than nonsheared PVWF multimers, as indicated in the higher peak unfolding force. These results provide insight into the mechanism of shear-induced activation of PVWF multimers.

Desialylation accelerates platelet clearance after refrigeration and initiates GPIbα metalloproteinase-mediated cleavage in mice.

PubMed

Jansen, A J Gerard; Josefsson, Emma C; Rumjantseva, Viktoria; Liu, Qiyong Peter; Falet, Hervé; Bergmeier, Wolfgang; Cifuni, Stephen M; Sackstein, Robert; von Andrian, Ulrich H; Wagner, Denisa D; Hartwig, John H; Hoffmeister, Karin M

2012-02-02

When refrigerated platelets are rewarmed, they secrete active sialidases, including the lysosomal sialidase Neu1, and express surface Neu3 that remove sialic acid from platelet von Willebrand factor receptor (VWFR), specifically the GPIbα subunit. The recovery and circulation of refrigerated platelets is greatly improved by storage in the presence of inhibitors of sialidases. Desialylated VWFR is also a target for metalloproteinases (MPs), because GPIbα and GPV are cleaved from the surface of refrigerated platelets. Receptor shedding is inhibited by the MP inhibitor GM6001 and does not occur in Adam17(ΔZn/ΔZn) platelets expressing inactive ADAM17. Critically, desialylation in the absence of MP-mediated receptor shedding is sufficient to cause the rapid clearance of platelets from circulation. Desialylation of platelet VWFR therefore triggers platelet clearance and primes GPIbα and GPV for MP-dependent cleavage.

Autoantibodies against complement components in systemic lupus erythematosus - role in the pathogenesis and clinical manifestations.

PubMed

Hristova, M H; Stoyanova, V S

2017-12-01

Many complement structures and a number of additional factors, i.e. autoantibodies, receptors, hormones and cytokines, are implicated in the complex pathogenesis of systemic lupus erythematosus. Genetic defects in the complement as well as functional deficiency due to antibodies against its components lead to different pathological conditions, usually clinically presented. Among them hypocomplementemic urticarial vasculitis, different types of glomerulonephritis as dense deposit disease, IgA nephropathy, atypical haemolytic uremic syndrome and lupus nephritis are very common. These antibodies cause conformational changes leading to pathological activation or inhibition of complement with organ damage and/or limited capacity of the immune system to clear immune complexes and apoptotic debris. Finally, we summarize the role of complement antibodies in the pathogenesis of systemic lupus erythematosus and discuss the mechanism of some related clinical conditions such as infections, thyroiditis, thrombosis, acquired von Willebrand disease, etc.

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.

Biochemical and functional characterization of a recombinant monomeric factor VIII-Fc fusion protein.

PubMed

Peters, R T; Toby, G; Lu, Q; Liu, T; Kulman, J D; Low, S C; Bitonti, A J; Pierce, G F

2013-01-01

Hemophilia A results from a deficiency in factor VIII activity. Current treatment regimens require frequent dosing, owing to the short half-life of FVIII. A recombinant FVIII-Fc fusion protein (rFVIIIFc) was molecularly engineered to increase the half-life of FVIII, by 1.5-2-fold, in several preclinical animal models and humans. To perform a biochemical and functional in vitro characterization of rFVIIIFc, with existing FVIII products as comparators.  rFVIIIFc was examined by utilizing a series of structural and analytic assays, including mass spectrometry following lysyl endopeptidase or thrombin digestion. rFVIIIFc activity was determined in both one-stage clotting (activated partial thromboplastin time) and chromogenic activity assays, in the context of the FXase complex with purified components, and in both in vitro and ex vivo rotational thromboelastometry (ROTEM) assays performed in whole blood.  rFVIIIFc contained the predicted primary structure and post-translational modifications, with an FVIII moiety that was similar to other recombinant FVIII products. The von Willebrand factor-binding and specific activity of rFVIIIFc were also found to be similar to those of other recombinant FVIII molecules. Both chromogenic and one-stage assays of rFVIIIFc gave similar results. Ex vivo ROTEM studies demonstrated that circulating rFVIIIFc activity was prolonged in mice with hemophilia A in comparison with B-domain-deleted or full-length FVIII. Clot parameters at early time points were similar to those for FVIII, whereas rFVIIIFc showed prolonged improvement of clot formation.  rFVIIIFc maintains normal FVIII interactions with other proteins necessary for its activity, with prolonged in vivo activity, owing to fusion with the Fc region of IgG(1) . © 2012 International Society on Thrombosis and Haemostasis.

Die Kosmogonie Anton von Zachs.

NASA Astrophysics Data System (ADS)

Brosche, P.

In his "Cosmogenische Betrachtungen" (1804), Anton von Zach rediscovered - probably independently - some aspects of the theories of Kant and Laplace. More originally, he envisaged also the consequences of an era of heavy impacts in the early history of the Earth.

An immunohistochemical analysis of canine haemangioma and haemangiosarcoma.

PubMed

Sabattini, S; Bettini, G

2009-01-01

The aim of the present study was to investigate immunohistochemically aspects of the biology of canine endothelial neoplasia. Forty samples of canine cutaneous and visceral haemangiosarcoma (HSA), 29 samples of cutaneous and visceral haemangioma (HA) and 10 control samples of granulation tissue (GT) were labelled with antisera specific for vimentin, smooth muscle actin, von Willebrand factor (vWF), CD117 (KIT), vascular endothelial growth factor receptor-3 (VEGFR-3), vascular endothelial growth factor-C (VEGFC) and CD44. Further antisera were employed to determine the level of cellular proliferation (MIB-1 index) and toluidine blue staining was used to detect populations of tumour-infiltrating mast cells (MCs). There was greater expression of CD117, VEGFR-3 and CD44 in HSA than in HA, suggesting that these proteins might be suitable targets for the future development of novel therapeutic approaches to canine HSA. Marked infiltration of MC was detected in HA, suggesting a possible role for these cells in the pathogenesis of benign vascular neoplasia in the dog.

Hemophilia in Sports: A Case Report and Prophylactic Protocol

PubMed Central

Maffet, Mark; Roton, Jimmy

2017-01-01

Objective: To describe a successful prophylactic protocol for managing an athlete with hemophilia playing at a high level of contact sports. Background: Published data show that team physicians are not comfortable either treating athletes with bleeding disorders or allowing them to participate in contact sports. Much of the literature historically has recommended against allowing athletes with bleeding disorders to play sports at all and certainly against playing contact sports. Hemophilia treatment can now include prophylactic injections of recombinant factor VIII to prevent bleeding episodes. Modern treatments hold the promise of allowing athletes with hemophilia to participate in contact sports. Differential Diagnosis: Mild, moderate, or severe hemophilia; von Willebrand disease; other factor deficiencies. Treatment: A treatment protocol was developed that included prophylactic factor VIII injections on a regular basis and when the athlete was injured. Uniqueness: This is the first published case report of an athlete with known hemophilia being successfully treated and participating in National Collegiate Athletic Association collegiate basketball for 2 full seasons. Conclusions: Sports medicine teams can successfully manage an athlete with hemophilia playing a contact sport. PMID:27863189

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.

Dr. Wernher Von Braun

NASA Technical Reports Server (NTRS)

1999-01-01

Marshall Space Flight Center director Wernher Von Braun and his family were honored with a series of events prior to his relocation to Washington, D.C. where he was assigned duties at NASA headquarters as deputy associate administrator for planning. Here he is shown with General Richard Drury and Hazel Toftoy, widow of General H.N. Toftoy.

Biomarkers and mortality after transient ischemic attack and minor ischemic stroke: population-based study.

PubMed

Greisenegger, Stefan; Segal, Helen C; Burgess, Annette I; Poole, Debbie L; Mehta, Ziyah; Rothwell, Peter M

2015-03-01

Premature death after transient ischemic attack or stroke is more often because of heart disease or cancer than stroke. Previous studies found blood biomarkers not usefully predictive of nonfatal stroke but possibly of all-cause death. This association might be explained by potentially treatable occult cardiac disease or cancer. We therefore aimed to validate the association of a panel of biomarkers with all-cause death, particularly cardiac death and cancer death, despite the absence of associations with risk of nonfatal vascular events. Fifteen biomarkers were measured in 929 consecutive patients in a population-based study (Oxford Vascular Study), recruited from 2002 and followed up to 2013. Associations were determined by Cox regression. Model discrimination was assessed by c-statistic and the integrated discrimination improvement. During 5560 patient-years of follow-up, none of the biomarkers predicted risk of nonfatal vascular events. However, soluble tumor necrosis factor α receptor-1, von Willebrand factor, heart-type fatty-acid-binding protein, and N-terminal pro-B-type natriuretic peptide were independently predictive of all-cause death (n=361; adjusted hazard ratio per SD, 95% confidence interval: heart-type fatty-acid-binding protein: 1.31, 1.12-1.56, P=0.002; N-terminal pro-B-type natriuretic peptide: 1.34, 1.11-1.62, P=0.002; soluble tumor necrosis factor α receptor-1: 1.45, 1.26-1.66, P=0.02; von Willebrand factor: 1.19, 1.04-1.36, P=0.01). The independent contribution of the four biomarkers taken together added prognostic information and improved model discrimination (integrated discrimination improvement=0.028, P=0.0001). N-terminal pro-B-type natriuretic peptide was most predictive of vascular death (adjusted hazard ratio=1.80, 95% confidence interval, 1.34-2.41, P<0.0001), whereas heart-type fatty-acid-binding protein predicted cancer deaths (1.64, 1.26-2.12, P=0.0002). Associations were strongest in patients without known prior cardiac disease

Zuverlässigkeit digitaler Schaltungen unter Einfluss von intrinsischem Rauschen

NASA Astrophysics Data System (ADS)

Kleeberger, V. B.; Schlichtmann, U.

2011-08-01

Die kontinuierlich fortschreitende Miniaturisierung in integrierten Schaltungen führt zu einem Anstieg des intrinsischen Rauschens. Um den Einfluss von intrinsischem Rauschen auf die Zuverlässigkeit zukünftiger digitaler Schaltungen analysieren zu können, werden Methoden benötigt, die auf CAD-Verfahren wie Analogsimulation statt auf abschätzenden Berechnungen beruhen. Dieser Beitrag stellt eine neue Methode vor, die den Einfluss von intrinsischem Rauschen in digitalen Schaltungen für eine gegebene Prozesstechnologie analysieren kann. Die Amplituden von thermischen, 1/f und Schrotrauschen werden mit Hilfe eines SPICE Simulators bestimmt. Anschließend wird der Einfluss des Rauschens auf die Schaltungszuverlässigkeit durch Simulation analysiert. Zusätzlich zur Analyse werden Möglichkeiten aufgezeigt, wie die durch Rauschen hervorgerufenen Effekte im Schaltungsentwurf mit berücksichtigt werden können. Im Gegensatz zum Stand der Technik kann die vorgestellte Methode auf beliebige Logikimplementierungen und Prozesstechnologien angewendet werden. Zusätzlich wird gezeigt, dass bisherige Ansätze den Einfluss von Rauschen bis um das Vierfache überschätzen.

mRNAs for PRPs, statherin, and histatins in von Ebner's gland tissues.

PubMed

Azen, E A; Hellekant, G; Sabatini, L M; Warner, T F

1990-11-01

A search was made for expression of genes for proline-rich proteins (PRPs) and other salivary-type proteins, including statherin and histatins, in taste-bud tissues of mice and primates because of previous genetic findings in mice (Azen et al., 1986) that Prp and taste genes for certain bitter substances are either the same or closely linked. Taste-bud tissues and other tissues were tested for specific mRNAs with labeled DNA probes by Northern blotting and in situ hybridization. It was found that PRP mRNAs were present in von Ebner's glands of mice and macaques, and that there was a much greater degree of PRP mRNA induction in mouse parotid (16-fold) than in von Ebner's gland (two-fold) after in vivo isoproterenol stimulation. This difference may be due, in part, to differences in autonomic nerve innervation. Statherin and histatin mRNAs were found in macaque taste-bud tissues containing von Ebner's gland, and statherin protein was found in human von Ebner's gland by immunohistochemistry. The finding of PRP gene expression in von Ebner's gland, whose secretions have been suggested to play a role in taste stimulation, adds further support to a possible function of PRPs in bitter tasting. The possible functions of statherin and histatins in von Ebner's gland secretions may be related to statherin's regulation of salivary calcium and histatins' antibacterial and antifungal properties.

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…

Wernher von Braun

NASA Image and Video Library

1966-06-21

Dr. Joseph Randall, a laser expert at Marshall Space Flight Center (MSFC), explains one of the projects he is working on to a group composed of Federal Republic of Germany and MSFC officials. From left are: Dr. Randall; Minister for Scientific Research of Federal Republic of Germany, Dr. Gerhard Stolenberg; Director of MSFC Astrionics Lab, Dr. Walter Haeusserman; Head of Space Research Federal Republic of Germany, Max Mayer; MSFC Director Dr. von Braun; MSFC Deputy Director Dr. Elberhard Rees.

Wernher von Braun

NASA Image and Video Library

1968-10-01

Dr. von Braun inside the KC-135 in flight. The KC-135 provide NASA's Reduced-Gravity Program the unique weightlessness or zero-g environment of space flight for testing and training of human and hardware reactions. The recent version, KC-135A, is a specially modified turbojet transport which flies parabolic arcs to produce weightlessness periods of 20 to 25 seconds and its cargo bay test area is approximately 60 feet long, 10 feet wide, and 7 feet high.

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.

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. Copyright © 2013 Elsevier Ltd. All rights reserved.

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.

In Situ Blood Vessel Regeneration Using SP (Substance P) and SDF (Stromal Cell-Derived Factor)-1α Peptide Eluting Vascular Grafts.

PubMed

Shafiq, Muhammad; Zhang, Qiuying; Zhi, Dengke; Wang, Kai; Kong, Deling; Kim, Dong-Hwee; Kim, Soo Hyun

2018-05-31

The objective of this study was to develop small-diameter vascular grafts capable of eluting SDF (stromal cell-derived factor)-1α-derived peptide and SP (substance P) for in situ vascular regeneration. Polycaprolactone (PCL)/collagen grafts containing SP or SDF-1α-derived peptide were fabricated by electrospinning. SP and SDF-1α peptide-loaded grafts recruited significantly higher mesenchymal stem cells than that of the control group. The in vivo potential of PCL/collagen, SDF-1, and SP grafts was assessed by implanting them in a rat abdominal aorta for up to 4 weeks. All grafts remained patent as observed using color Doppler and stereomicroscope. Host cells infiltrated into the graft wall and the neointima was formed in peptides-eluting grafts. The lumen of the SP grafts was covered by the endothelial cells with cobblestone-like morphology, which were elongated in the direction of the blood flow, as discerned using scanning electron microscopy. Moreover, SDF-1α and SP grafts led to the formation of a confluent endothelium as evaluated using immunofluorescence staining with von Willebrand factor antibody. SP and SDF-1α grafts also promoted smooth muscle cell regeneration, endogenous stem cell recruitment, and blood vessel formation, which was the most prominent in the SP grafts. Evaluation of inflammatory response showed that 3 groups did not significantly differ in terms of the numbers of proinflammatory macrophages, whereas SP grafts showed significantly higher numbers of proremodeling macrophages than that of the control and SDF-1α grafts. SDF-1α and SP grafts can be potential candidates for in situ vascular regeneration and are worthy for future investigations. © 2018 American Heart Association, Inc.

Variation in baseline factor VIII concentration in a retrospective cohort of mild/moderate hemophilia A patients carrying identical F8 mutations.

PubMed

Loomans, J I; van Velzen, A S; Eckhardt, C L; Peters, M; Mäkipernaa, A; Holmstrom, M; Brons, P P; Dors, N; Haya, S; Voorberg, J; van der Bom, J G; Fijnvandraat, K

2017-02-01

Essentials Factor VIII levels vary in mild and moderate hemophilia A (MHA) patients with the same mutation. We aimed to estimate the variation and determinants of factor VIII levels among MHA patients. Age and genotype explain 59% of the observed inter-individual variation in factor VIII levels. Intra-individual variation accounted for 45% of the variation in the three largest mutation groups. Background The bleeding phenotype in patients with mild/moderate hemophilia A (MHA) is inversely associated with the residual plasma concentration of factor VIII (FVIII:C). Within a group of patients with the same F8 missense mutation, baseline FVIII:C may vary, because, in healthy individuals, von Willebrand factor (VWF) levels, ABO blood group and age are also known to influence baseline FVIII:C. Our understanding of the pathophysiologic process of the causative genetic event leading to reduced baseline FVIII:C in MHA patients is still limited. Objectives To estimate the variation and determinants of baseline FVIII:C among MHA patients with the same F8 missense mutation. Methods Three hundred and forty-six patients carrying mutations that were present in at least 10 patients in the cohort were selected from the INSIGHT and the RISE studies, which are cohort studies including data of 3534 MHA patients from Europe, Canada, and Australia. Baseline FVIII:C was measured with a one-stage clotting assay. We used Levene's test, univariate and multivariate linear regression, and mixed-model analyses. Results For 59% of patients, the observed variation in baseline FVIII:C was explained by age and genotype. Compared to FVIII:C in patients with Arg612Cys, FVIII:C was significantly different in patients with eight other F8 missense mutations. Intra-individual variation explained 45% of the observed variance in baseline FVIII:C among patients with the same mutation. Conclusion Our results indicate that baseline FVIII:C levels are not exclusively determined by F8 genotype in MHA patients

Wernher von Braun

NASA Image and Video Library

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.

Is anti-platelet therapy needed in continuous flow left ventricular assist device patients? A single-centre experience.

PubMed

Litzler, Pierre-Yves; Smail, Hassiba; Barbay, Virginie; Nafeh-Bizet, Catherine; Bouchart, François; Baste, Jean-Marc; Abriou, Caroline; Bessou, Jean-Paul

2014-01-01

We report our 5-year experience of continuous flow left ventricular assist device (LVAD) implantation without the use of anti-platelet therapy. Between February 2006 and September 2011, 27 patients (26 men; 1 woman) were implanted with a continuous flow LVAD (HeartMate II, Thoratec Corporation, Pleasanton, CA, USA). The mean age was 55.7 ± 9.9 years. The mean duration of support was 479 ± 436 (1-1555) days with 35.4 patient-years on support. Twenty-one patients were implanted as a bridge to transplantation and 6 for destination therapy. The anticoagulation regimen was fluindione for all patients, with aspirin for only 4 patients. At the beginning of our experience, aspirin was administered to 4 patients for 6, 15, 60 and 460 days. Due to gastrointestinal (GI) bleeding and epistaxis, aspirin was discontinued, and since August 2006, no patients have received anti-platelet therapy. At 3 years, the survival rate during support was 76%. The most common postoperative adverse event was GI bleeding (19%) and epistaxis (30%) (median time: 26 days) for patients receiving fluindione and aspirin. The mean International Normalized Ratio (INR) was 2.58 ± 0.74 during support. Fifteen patients have been tested for acquired Von Willebrand disease. A diminished ratio of collagen-binding capacity and ristocetin cofactor activity to Von Willebrand factor antigen was observed in 7 patients. In the postoperative period, 2 patients presented with ischaemic stroke at 1 and 8 months. One of these 2 patients had a previous history of carotid stenosis with ischaemic stroke. There were no patients with haemorrhagic stroke, transient ischaemic attack or pump thrombosis. The event rate of stroke (ischaemic and haemorrhagic) per patient-year was 0.059 among the patients without aspirin with fluindione regimen only. A fluindione regimen without aspirin in long-duration LVAD support appears to not increase thromboembolic events and could lead to a diminished risk of haemorrhagic stroke.

Molecular quantum control landscapes in von Neumann time-frequency phase space

NASA Astrophysics Data System (ADS)

Ruetzel, Stefan; Stolzenberger, Christoph; Fechner, Susanne; Dimler, Frank; Brixner, Tobias; Tannor, David J.

2010-10-01

Recently we introduced the von Neumann representation as a joint time-frequency description for femtosecond laser pulses and suggested its use as a basis for pulse shaping experiments. Here we use the von Neumann basis to represent multidimensional molecular control landscapes, providing insight into the molecular dynamics. We present three kinds of time-frequency phase space scanning procedures based on the von Neumann formalism: variation of intensity, time-frequency phase space position, and/or the relative phase of single subpulses. The shaped pulses produced are characterized via Fourier-transform spectral interferometry. Quantum control is demonstrated on the laser dye IR140 elucidating a time-frequency pump-dump mechanism.

Molecular quantum control landscapes in von Neumann time-frequency phase space.

PubMed

Ruetzel, Stefan; Stolzenberger, Christoph; Fechner, Susanne; Dimler, Frank; Brixner, Tobias; Tannor, David J

2010-10-28

Recently we introduced the von Neumann representation as a joint time-frequency description for femtosecond laser pulses and suggested its use as a basis for pulse shaping experiments. Here we use the von Neumann basis to represent multidimensional molecular control landscapes, providing insight into the molecular dynamics. We present three kinds of time-frequency phase space scanning procedures based on the von Neumann formalism: variation of intensity, time-frequency phase space position, and/or the relative phase of single subpulses. The shaped pulses produced are characterized via Fourier-transform spectral interferometry. Quantum control is demonstrated on the laser dye IR140 elucidating a time-frequency pump-dump mechanism.

Identification and characterization of multiple rubisco activases in chemoautotrophic bacteria

PubMed Central

Tsai, Yi-Chin Candace; Lapina, Maria Claribel; Bhushan, Shashi; Mueller-Cajar, Oliver

2015-01-01

Ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco) is responsible for almost all biological CO2 assimilation, but forms inhibited complexes with its substrate ribulose-1,5-bisphosphate (RuBP) and other sugar phosphates. The distantly related AAA+ proteins rubisco activase and CbbX remodel inhibited rubisco complexes to effect inhibitor release in plants and α-proteobacteria, respectively. Here we characterize a third class of rubisco activase in the chemolithoautotroph Acidithiobacillus ferrooxidans. Two sets of isoforms of CbbQ and CbbO form hetero-oligomers that function as specific activases for two structurally diverse rubisco forms. Mutational analysis supports a model wherein the AAA+ protein CbbQ functions as motor and CbbO is a substrate adaptor that binds rubisco via a von Willebrand factor A domain. Understanding the mechanisms employed by nature to overcome rubisco's shortcomings will increase our toolbox for engineering photosynthetic carbon dioxide fixation. PMID:26567524

Nucleation of platelets with blood-borne pathogens on Kupffer cells precedes other innate immunity and contributes to bacterial clearance.

PubMed

Wong, Connie H Y; Jenne, Craig N; Petri, Björn; Chrobok, Navina L; Kubes, Paul

2013-08-01

Through the use of intravital imaging of the liver, we demonstrate a collaborative role for platelets with Kupffer cells (KCs) in eradicating blood-borne bacterial infection. Under basal conditions, platelets, via the platelet-adhesion receptor GPIb, formed transient 'touch-and-go' interactions with von Willebrand factor (vWF) constitutively expressed on KCs. Bacteria such as Bacillus cereus and methicillin-resistant Staphylococcus aureus (MRSA) were rapidly caught by KCs and triggered platelets to switch from 'touch-and-go' adhesion to sustained GPIIb-mediated adhesion on the KC surface to encase the bacterium. Infected GPIbα-deficient mice had more endothelial and KC damage than did their wild-type counterparts, which led to more fluid leakage, substantial polycythemia and rapid mortality. Our study identifies a previously unknown surveillance mechanism by which platelets survey macrophages that rapidly converts to a critical host response to blood-borne bacteria.

Discontinuation of antithrombotic therapy for a year or more in patients with continuous-flow left ventricular assist devices.

PubMed

Pereira, Naveen L; Chen, Dong; Kushwaha, Sudhir S; Park, Soon J

2010-10-01

The recommended anticoagulation regimen during continuous-flow axial left ventricular assist device (LVAD) support is aspirin and warfarin with a targeted international normalized ratio of 2.0-3.0. We report two patients in whom recurrent gastrointestinal bleeding during LVAD support necessitated discontinuation of this anti-thrombotic regimen for a year or more. Despite this, neither patients developed thrombotic complications during 29 patient-months of follow-up. An acquired von Willebrand factor (VWF) abnormality reflected by the absence or decreased abundance of the highest molecular weight multimers was demonstrated in both patients. The gold standard test for platelet function, light transmission platelet aggregometry was measured in one patient and was normal, indicative that the predominant abnormality in the coagulation profile of these patients is an acquired VWF syndrome. Clinical trials are required to address the question whether it is safe to discontinue anticoagulation in LVAD patients with acquired VWF abnormalities.

Role of high shear rate in thrombosis.

PubMed

Casa, Lauren D C; Deaton, David H; Ku, David N

2015-04-01

Acute arterial occlusions occur in high shear rate hemodynamic conditions. Arterial thrombi are platelet-rich when examined histologically compared with red blood cells in venous thrombi. Prior studies of platelet biology were not capable of accounting for the rapid kinetics and bond strengths necessary to produce occlusive thrombus under these conditions where the stasis condition of the Virchow triad is so noticeably absent. Recent experiments elucidate the unique pathway and kinetics of platelet aggregation that produce arterial occlusion. Large thrombi form from local release and conformational changes in von Willebrand factor under very high shear rates. The effect of high shear hemodynamics on thrombus growth has profound implications for the understanding of all acute thrombotic cardiovascular events as well as for vascular reconstructive techniques and vascular device design, testing, and clinical performance. Copyright © 2015 Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.

Desialylation accelerates platelet clearance after refrigeration and initiates GPIbα metalloproteinase-mediated cleavage in mice

PubMed Central

Jansen, A. J. Gerard; Josefsson, Emma C.; Rumjantseva, Viktoria; Liu, Qiyong Peter; Falet, Hervé; Bergmeier, Wolfgang; Cifuni, Stephen M.; Sackstein, Robert; von Andrian, Ulrich H.; Wagner, Denisa D.; Hartwig, John H.

2012-01-01

When refrigerated platelets are rewarmed, they secrete active sialidases, including the lysosomal sialidase Neu1, and express surface Neu3 that remove sialic acid from platelet von Willebrand factor receptor (VWFR), specifically the GPIbα subunit. The recovery and circulation of refrigerated platelets is greatly improved by storage in the presence of inhibitors of sialidases. Desialylated VWFR is also a target for metalloproteinases (MPs), because GPIbα and GPV are cleaved from the surface of refrigerated platelets. Receptor shedding is inhibited by the MP inhibitor GM6001 and does not occur in Adam17ΔZn/ΔZn platelets expressing inactive ADAM17. Critically, desialylation in the absence of MP-mediated receptor shedding is sufficient to cause the rapid clearance of platelets from circulation. Desialylation of platelet VWFR therefore triggers platelet clearance and primes GPIbα and GPV for MP-dependent cleavage. PMID:22101895

[Precocious puberty and von Recklinghausen's disease].

PubMed

Barg, Ewa; Wikiera, Beata; Basiak, Aleksander; Głab, Ewa

2006-01-01

Von Recklinghausen's disease belongs to a group of neurocutaneous syndromes and is characterised by skin, nerve and bone abnormalities. We present a case of von Recklinghausen's disease and precocious puberty in 7-year-old boy. At the age of three café au lait spots on the skin and an incranial tumour situated near the optic chiasm--qualified as inoperable--were discovered. At the age of 7 first signs of precocious puberty appeared (pubic hair P3 and enlargement of the testes (15 ml) and penis). Laboratory measurements included: LH 7.5 mIU/ml, FSH 1.1 mIU/ml, testosterone 183 ng/ml, assessment of bone age: 9 years. The response to LHRH stimulation was characteristic for true precocious puberty (LH 15.9 mIU/ml and FSH 1.5 mIU/ml after 30 minutes). The MRI of the brain showed a tumour of the suprasellar region with compression of pituitary stalk. True precocious puberty was diagnosed. Treatment with Diphereline was introduced. At present the boy is 9 years old and has been treated with Diphereline for 16 months. The volume of the testicles has decreased to 7 ml and loss of pubic hair was noted. The MRI does not show any progression in tumour growth. The authors would like to underline the need of close observation of children with von Reclinghausen disease with regard to possibility of uncovering true precocious puberty which is critical for rapid diagnosis and introduction of correct treatment.

Defibrotide prevents the activation of macrovascular and microvascular endothelia caused by soluble factors released to blood by autologous hematopoietic stem cell transplantation.

PubMed

Palomo, Marta; Diaz-Ricart, Maribel; Rovira, Montserrat; Escolar, Ginés; Carreras, Enric

2011-04-01

Endothelial activation and damage occur in association with autologous hematopoietic stem cell transplantation (HSCT). Several of the early complications associated with HSCT seem to have a microvascular location. Through the present study, we have characterized the activation and damage of endothelial cells of both macro (HUVEC) and microvascular (HMEC) origin, occurring early after autologous HSCT, and the potential protective effect of defibrotide (DF). Sera samples from patients were collected before conditioning (Pre), at the time of transplantation (day 0), and at days 7, 14, and 21 after autologous HSCT. Changes in the expression of endothelial cell receptors at the surface, presence and reactivity of extracellular adhesive proteins, and the signaling pathways involved were analyzed. The expression of ICAM-1 at the cell surface increased progressively in both HUVEC and HMEC. However, a more prothrombotic profile was denoted for HMEC, in particular at the time of transplantation (day 0), reflecting the deleterious effect of the conditioning treatment on the endothelium, especially at a microvascular location. Interestingly, this observation correlated with a higher increase in the expression of both tissue factor and von Willebrand factor on the extracellular matrix, together with activation of intracellular p38 MAPK and Akt. Previous exposure and continuous incubation of cells with DF prevented the signs of activation and damage induced by the autologous sera. These observations corroborate that conditioning treatment in autologous HSCT induces a proinflammatory and a prothrombotic phenotype, especially at a microvascular location, and indicate that DF has protective antiinflammatory and antithrombotic effects in this setting. Copyright © 2011 American Society for Blood and Marrow Transplantation. Published by Elsevier Inc. All rights reserved.

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.

The smooth entropy formalism for von Neumann algebras

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berta, Mario, E-mail: berta@caltech.edu; Furrer, Fabian, E-mail: furrer@eve.phys.s.u-tokyo.ac.jp; Scholz, Volkher B., E-mail: scholz@phys.ethz.ch

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.

Hazardous Waste Cleanup: Von Roll Isola USA Incorporated in Schenectady, New York

EPA Pesticide Factsheets

The Riverview facility is a 52-acre manufacturing facility located on Von Roll Drive in Schenectady, New York. The facility is owned and operated by Von Roll Isola USA, Inc., and produces solid and liquid insulating materials and tapes for the electrical

Die nuklearen Anlagen von Hanford (1943-1987) Eine Fallstudie über die Schnittstellen von Physik, Biologie und die US-amerikanische Gesellschaft zur Zeit des Kalten Krieges

NASA Astrophysics Data System (ADS)

Macuglia, Daniele

Die Geschichte des Kalten Krieges eröffnet viele Möglichkeiten, sich näher mit den Schnittstellen von Physik und Biologie während des 20. Jahrhunderts zu befassen. Nicht nur das Unglück in Tschernobyl aus dem Jahr 1986, auch das Beispiel der nuklearen Anlagen in Hanford in den Vereinigten Staaten zeigt die biologischen Folgen von nuklearer Physik.

Von Neumann entropy in a Rashba-Dresselhaus nanodot; dynamical electronic spin-orbit entanglement

NASA Astrophysics Data System (ADS)

Safaiee, Rosa; Golshan, Mohammad Mehdi

2017-06-01

The main purpose of the present article is to report the characteristics of von Neumann entropy, thereby, the electronic hybrid entanglement, in the heterojunction of two semiconductors, with due attention to the Rashba and Dresselhaus spin-orbit interactions. To this end, we cast the von Neumann entropy in terms of spin polarization and compute its time evolution; with a vast span of applications. It is assumed that gate potentials are applied to the heterojunction, providing a two dimensional parabolic confining potential (forming an isotropic nanodot at the junction), as well as means of controlling the spin-orbit couplings. The spin degeneracy is also removed, even at electronic zero momentum, by the presence of an external magnetic field which, in turn, leads to the appearance of Landau states. We then proceed by computing the time evolution of the corresponding von Neumann entropy from a separable (spin-polarized) initial state. The von Neumann entropy, as we show, indicates that electronic hybrid entanglement does occur between spin and two-dimensional Landau levels. Our results also show that von Neumann entropy, as well as the degree of spin-orbit entanglement, periodically collapses and revives. The characteristics of such behavior; period, amplitude, etc., are shown to be determined from the controllable external agents. Moreover, it is demonstrated that the phenomenon of collapse-revivals' in the behavior of von Neumann entropy, equivalently, electronic hybrid entanglement, is accompanied by plateaus (of great importance in quantum computation schemes) whose durations are, again, controlled by the external elements. Along these lines, we also make a comparison between effects of the two spin-orbit couplings on the entanglement (von Neumann entropy) characteristics. The finer details of the electronic hybrid entanglement, which may be easily verified through spin polarization measurements, are also accreted and discussed. The novel results of the present

Monoclonal antibodies to alphaVbeta3 (7E3 and LM609) inhibit sickle red blood cell-endothelium interactions induced by platelet-activating factor.

PubMed

Kaul, D K; Tsai, H M; Liu, X D; Nakada, M T; Nagel, R L; Coller, B S

2000-01-15

Abnormal interaction of sickle red blood cells (SS RBC) with the vascular endothelium has been implicated as a factor in the initiation of vasoocclusion in sickle cell anemia. Both von Willebrand factor (vWf) and thrombospondin (TSP) play important roles in mediating SS RBC-endothelium interaction and can bind to the endothelium via alphaVbeta3 receptors. We have used monoclonal antibodies (MoAb) directed against alphaVbeta3 and alphaIIbbeta3 (GPIIb/IIIa) integrins to dissect the role of these integrins in SS RBC adhesion. The murine MoAb 7E3 inhibits both alphaVbeta3 and alphaIIbbeta3 (GPIIb/IIIa), whereas MoAb LM609 selectively inhibits alphaVbeta3, and MoAb 10E5 binds only to alphaIIbbeta3. In this study, we have tested the capacity of these MoAbs to block platelet-activating factor (PAF)-induced SS RBC adhesion in the ex vivo mesocecum vasculature of the rat. Infusion of washed SS RBC in preparations treated with PAF (200 pg/mL), with or without a control antibody, resulted in extensive adhesion of these cells in venules, accompanied by frequent postcapillary blockage and increased peripheral resistance units (PRU). PAF also caused increased endothelial surface and interendothelial expression of endothelial vWf. Importantly, pretreatment ofthe vasculature with either MoAb 7E3 F(ab')(2) or LM609, but not 10E5 F(ab')(2), after PAF almost completely inhibited SS RBC adhesion in postcapillary venules, the sites of maximal adhesion and frequent blockage. The inhibition of adhesion with 7E3 or LM609 was accompanied by smaller increases in PRU and shorter pressure-flow recovery times. Thus, blockade of alphaVbeta3 may constitute a potential therapeutic approach to prevent SS RBC-endothelium interactions under flow conditions. (Blood. 2000;95:368-374)

Detection of bleeding disorders in Lebanon: outcomes of a pilot programme.

PubMed

Djambas Khayat, C; Samaha, H; Noun, P; Bakhos Asmar, J D; Taher, A; Adib, S; Inati, A; Sakr, S

2014-03-01

To promote management and awareness of bleeding disorders in Lebanon, a pilot programme was launched in 2009 by the Lebanese Hemophilia Association assisted by World Federation of Hemophilia. The aim of this study was to diagnose patients with bleeding disorders and to assess the potential challenges in implementing a screening programme. The pilot project was launched in 26 social health centres in the Bekaa valley. The study tools included the evaluation of the Tossetto Bleeding Score and the Pictorial Bleeding Assessment Chart (PBAC) for menstruation. Persons with a bleeding score higher than 2 and PBAC higher than 185 were eligible for further blood tests including the prothrombin time, partial thromboplastin time, complete blood count, bleeding time and von Willebrand ristocetin cofactor activity. 643 patients were enrolled, of whom 60.6% were women. Overall, 91 persons had an abnormal score. 50 eligible patients were tested: 32 had normal tests, nine new patients with severe Von Willebrand were discovered, 4 had VW:RiCo of 40, 3 prolonged APTT and 2 thrombocytopaenia. There was a clear correlation between the severity of the score and the willingness to perform the tests (P = 0.02). Women were reluctant to participate fully when investigators were men. The probability of adherence to the screening protocol is significantly increased when directed by women health care professional. For patients with milder forms, global screening programmes were neither feasible nor acceptable but those more severely affected have to be identified. Providers are crucial in preselecting patients with blood problems who are not coping well. © 2013 John Wiley & Sons Ltd.

Wernher von Braun

NASA Image and Video Library

1965-05-25

This image depicts the tension in the Launch Control Center of the Launch Complex 37 at Cape Canaveral, Florida, during the SA-8 on May 25, 1965. Pointing, center is Dr. Kurt Debus, Director, Launch Operations Directorate, MSFC. To the right is Dr. Hans Gruene, Deputy Director, Launch Operations Directorate, MSFC; Dr. von Braun, Director, Marshall Space Flight Center (MSFC); and leaning, Dr. Eberhard Rees, Director, Deputy Director for Research and Development, MSFC. The SA-8 mission, with a Saturn I launch vehicle, made the first night launch and deployed Pegasus II, micrometeoroid detection satellite.

Serum protein mediators of dementia and aging proper.

PubMed

Royall, Donald R; Al-Rubaye, Safa; Bishnoi, Ram; Palmer, Raymond F

2016-12-03

The latent variable "δ" (for "dementia") appears to be uniquely responsible for the dementing aspects of cognitive impairment. Age, depressive symptoms, gender and the apolipoprotein E (APOE) ε4 allele are independently associated with δ. In this analysis, we explore serum proteins as potential mediators of age's specific association with δ in a large, ethnically diverse longitudinal cohort, the Texas Alzheimer's Research and Care Consortium (TARCC). 22 serum proteins were recognized as partial mediators of age's association with δ. These include Insulin-like Growth Factor-Binding Protein 2 (IGF-BP2), which we had previously associated with age-specific cognitive change, and both Pancreatic Polypeptide (PP) and von Willebrand Factor (vWF), previously associated with δ. Nine other δ-related proteins were not confirmed by this ethnicity adjusted analysis. Our findings suggest that age's association with the disabling fraction of cognitive performance is partially mediated by serum proteins, somatomedins and hormones. Those proteins may offer targets for the specific treatment of age-related effects on dementia severity and conversion risk.

Effects of long term ethanol consumption mediated oxidative stress on neovessel generation in liver.

PubMed

Das, Subir Kumar; Mukherjee, Sukhes; Vasudevan, D M

2012-06-01

Angiogenesis, the growth of new blood vessels, is essential during tissue repair. Though most molecular mechanisms of angiogenesis are common to the liver and other organs, there was no report available whether alcoholic liver disease also causes angiogenesis. In this study, we examined the effects of long term ethanol (1.6 g/kg body weight/day) consumption on angiogenic responses in the liver of male Wistar strain albino rats (16-18 weeks old, weighing 200-220 g) up to 36 weeks. Chronic ethanol consumption was associated with not only elevated oxidative stress, and altered cytokines expression, but also developed large von Willebrand factor, fibrosis and activation of matrix metalloproteinases. Moreover, vascular endothelial growth factor-receptor 2 (VEGF-R2, fetal liver kinase 1: Flk-1/KDR) expression and neovessel generation in the rat liver were noted after 36 weeks of ethanol consumption. Thus our study provides novel evidence that long-term ethanol consumption is associated with angiogenesis through delicate and coordinated action of a variety of mediators.

Bleeding with the artificial heart: Gastrointestinal hemorrhage in CF-LVAD patients.

PubMed

Gurvits, Grigoriy E; Fradkov, Elena

2017-06-14

Continuous-flow left ventricular assist devices (CF-LVADs) have significantly improved outcomes for patients with end-stage heart failure when used as a bridge to cardiac transplantation or, more recently, as destination therapy. However, its implantations carries a risk of complications including infection, device malfunction, arrhythmias, right ventricular failure, thromboembolic disease, postoperative and nonsurgical bleeding. A significant number of left ventricular assist devices (LVAD) recipients may experience recurrent gastrointestinal hemorrhage, mainly due to combination of antiplatelet and vitamin K antagonist therapy, activation of fibrinolytic pathway, acquired von Willebrand factor deficiency, and tendency to develop small intestinal angiodysplasias due to increased rotary speed of the pump. Gastrointestinal bleeding in LVAD patients remains a source of increased morbidity including the need for blood transfusions, extended hospital stays, multiple readmissions, and overall mortality. Management of gastrointestinal bleeding in LVAD patients involves multidisciplinary approach in stabilizing the patients, addressing risk factors and performing structured endoluminal evaluation with focus on upper gastrointestinal tract including jejunum to find and eradicate culprit lesion. Medical and procedural intervention is largely successful and universal bleeding cessation occurs in transplanted patients.

Effects of Aerobic Fitness and Adiposity on Coagulation Biomarkers in Men vs. Women with Elevated Blood Pressure

PubMed Central

Wilson, Kathleen L.; Tomfohr, Lianne; Edwards, Kate; Knott, Cindy; Hong, Suzi; Redwine, Laura; Calfas, Karen; Rock, Cheryl L.; von Känel, Roland; Mills, Paul J.

2012-01-01

A hypercoagulable state is a potential mechanism linking elevated blood pressure (BP), adiposity and a sedentary lifestyle to development of coronary heart disease (CHD). We examined relationships among aerobic fitness and adiposity in 76 sedentary subjects with elevated BP. Blood levels of plasminogen activator inhibitor-1 (PAI-1), D-dimer, von Willebrand factor (vWF) and thrombomodulin were assessed as biomarkers of coagulation. In individuals with elevated BP, percent body fat and fitness were associated with biomarkers indicative of a hypercoagulable state, even after demographic and metabolic factors were considered. D-dimer was positively associated with percent body fat (beta=0.37, p=0.003). PAI-1 was higher in men than in women (beta=−0.31, p=0.015) and associated with lower VO2peak (beta=−0.35, p=0.024). Thrombomodulin was positively associated with VO2peak (beta=0.56, p< 0.01). vWF was not significantly associated with fitness or adiposity. Our results emphasise that both percent body fat and physical fitness are important in the maintenance of haemostatic balance. PMID:23105963

[Hemolytic and uremic syndrome and maternal-fetal Escherichia coli K1 infection].

PubMed

Flandrois, M; Bessière, A; Vieira-Roth, S; Vergnaud, M; Frémeaux-Bacchi, V; Eckart, P

2011-03-01

Hemolytic uremic syndrome (HUS) is primarily a disease of infancy and early childhood. In its classic form, it is preceded by a prodrome of Escherichia coli-mediated bloody mucoid diarrhea. Typical HUS is commonly related to an infection by shiga-toxin producing E. coli. Stool cultures may detect this bacteria or its toxin, and PCRs can detect the shiga-toxin virulence genes. Atypical cases of HUS are mainly related to abnormalities of the alternative complement pathway and mutations of H, I, or B factors. Some atypical cases of HUS may also be related to von Willebrand factor or vitamin B12 metabolism abnormalities. A number of HUS cases related to invasive pneumococcal infections (pneumonia or meningitis) have been reported. We report a case of HUS associated with a bacterial E. coli K1 infection in a newborn baby, with a good clinical outcome: there was no need for dialysis and normal renal function was quickly regained. The workup did not favor a toxinic origin or an abnormality on the alternative complement pathway. Copyright © 2010 Elsevier Masson SAS. All rights reserved.

Relationships of inflammatory and haemostatic markers with social class: results from a population-based study of older men.

PubMed

Ramsay, Sheena; Lowe, Gordon D O; Whincup, Peter H; Rumley, Ann; Morris, Richard W; Wannamethee, S Goya

2008-04-01

Haemostatic and inflammatory markers have been hypothesised to mediate the relationship of social class and cardiovascular disease (CVD). We investigated whether a range of inflammatory/haemostatic markers are associated with social class independent of chronic diseases and behavioural risk factors in a population-based sample of 2682 British men aged 60-79 without a physician diagnosis of CVD, diabetes or musculoskeletal disease requiring anti-inflammatory medications. Men in lower social classes had higher mean levels of C-reactive protein, fibrinogen, interleukin-6, white blood cell count, von Willebrand factor (vWF), factor VIII, activated protein C (APC) resistance, plasma viscosity, fibrin D-dimer and platelet count, compared to higher social class groups; but not of tissue plasminogen activator antigen, haematocrit or activated partial prothrombin time. After adjustment for behavioural risk factors (smoking, alcohol, physical activity and body mass), the associations of social class with vWF, factor VIII, APC resistance, plasma viscosity, and platelet count though weakened, remained statistically significant, while those of other markers were considerably attenuated. In this study of older men without CVD, the social gradient in inflammatory and haemostatic markers was substantially explained by behavioural risk factors. The effect of socio-economic gradient on the factor VIII-vWF complex, APC resistance, plasma viscosity and platelet count merits further study.

Genetics Home Reference: von Hippel-Lindau syndrome

MedlinePlus

... more common in particular ethnic groups? Genetic Changes Mutations in the VHL gene cause von Hippel-Lindau ... dividing too rapidly or in an uncontrolled way. Mutations in this gene prevent production of the VHL ...

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.

Update zum klinischen Einsatz von Inhibitoren mutierter Phosphokinasen beim Melanom.

PubMed

Cosgarea, Ioana; Ritter, Cathrin; Becker, Jürgen C; Schadendorf, Dirk; Ugurel, Selma

2017-09-01

Die Behandlungsstrategie beim metastasierten Melanom hat sich mit der Identifizierung therapeutisch angreifbarer molekularer Zielstrukturen innerhalb zellulärer Signalwege radikal geändert. Durch die Zulassung von Substanzen, die gezielt an den zentralen Schaltmolekülen, den Phosphokinasen, angreifen, können diese Signalwege selektiv abgeschaltet werden. Dies ist insbesondere bei denjenigen Tumoren von Interesse, deren Signalwege durch aktivierende Mutationen der für die Schaltmoleküle kodierenden Gene konstitutiv aktiviert sind. Aktuell ist diese therapeutische Strategie insbesondere für Patienten bedeutsam, deren Melanome eine Mutation im BRAF-Gen aufweisen. Diese Patienten können durch eine Kombinationstherapie aus Inhibitoren der Phosphokinasen BRAF und MEK langfristig mit sehr guter Krankheitskontrolle behandelt werden. Unter dieser Kombinationstherapie wird aktuell ein progressionsfreies Überleben von über zehn Monaten und ein Gesamtüberleben von mehr als zwei Jahren bei guter Lebensqualität erzielt. Da unter längerfristiger Therapie mit Kinaseinhibitoren jedoch bei einem Großteil der Patienten eine Resistenzbildung auftritt, sind aktuelle klinische Therapiestudien auf die Suche nach geeigneten Kombinationspartnern unter Blockierung anderer Signalwege oder unter Aktivierung der T-Zell-vermittelten Immunantwort ausgerichtet. Der vorliegende Übersichtsartikel stellt sowohl die aktuell verfügbaren als auch die in der klinischen Testung befindlichen zukünftigen Optionen der zielgerichteten Therapie des Melanoms dar. © 2017 Deutsche Dermatologische Gesellschaft (DDG). Published by John Wiley & Sons Ltd.

Wernher von Braun

NASA Image and Video Library

1959-03-01

In this photo, Director of the U.S. Army Ballistic Missile Agency's (ABMA) Development Operations Division, Dr. Wernher von Braun, and Director of Missile Firing Division, Dr. Kurt Debus, are shown with unidentified individuals, discussing two components that would make up the Pioneer IV Lunar Probe. The mercury batteries (left) were used to power the radio transmitter, cosmic radiation counter and other instruments in Pioneer IV. The conical shroud placed over the instruments of Pioneer IV was plated with gold to improve conductivity. The metal surface also served as the anterna for the probe's instruments signaling back to the Earth receiving stations.

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.

In Vivo Hypocholesterolemic Effect of MARDI Fermented Red Yeast Rice Water Extract in High Cholesterol Diet Fed Mice

PubMed Central

Beh, Boon Kee; Kong, Joan; Ho, Wan Yong; Mohd Yusof, Hamidah; Hussin, Aminuddin bin; Jaganath, Indu Bala; Alitheen, Noorjahan Banu; Jamaluddin, Anisah

2014-01-01

Fermented red yeast rice has been traditionally consumed as medication in Asian cuisine. This study aimed to determine the in vivo hypocholesterolemic and antioxidant effects of fermented red yeast rice water extract produced using Malaysian Agricultural Research and Development Institute (MARDI) Monascus purpureus strains in mice fed with high cholesterol diet. Absence of monacolin-k, lower level of γ-aminobutyric acid (GABA), higher content of total amino acids, and antioxidant activities were detected in MARDI fermented red yeast rice water extract (MFRYR). In vivo MFRYR treatment on hypercholesterolemic mice recorded similar lipid lowering effect as commercial red yeast rice extract (CRYR) as it helps to reduce the elevated serum liver enzyme and increased the antioxidant levels in liver. This effect was also associated with the upregulation of apolipoproteins-E and inhibition of Von Willebrand factor expression. In summary, MFRYR enriched in antioxidant and amino acid without monacolin-k showed similar hypocholesterolemic effect as CRYR that was rich in monacolin-k and GABA. PMID:25031606

Increased Levels of Metalloproteinase 10 and Hemostatic Markers in Patients With Noncomplicated Primary Varicose Veins.

PubMed

Dzieciuchowicz, Lukasz; Espinosa, Gaudencio; Páramo, José A

2015-10-01

The purpose of the study was to analyze a systemic activation of hemostasis and concentration of matrix metalloproteinase 10 (MMP-10) in patients with primary varicose veins (PVVs). A study group consisted of 41 patients with noncomplicated PVVs. A control group consisted of 30 age- and sex-matched healthy individuals without varicose veins. The concentration of d-dimers (DD), prothrombin fragments 1 and 2 (F1+2), antigen of von Willebrand factor (vWF), and activity of plasminogen activator inhibitor (PAI-1) in plasma and concentration of MMP-10 in serum were analyzed. In patients with PVVs, higher concentrations of DD (P < .001), F1+2 (P < .001), vWF (P = .027), MMP-10 (P = .006), and higher activity of PAI-1 (P < .001) were observed. However, no correlation between the concentrations of MMP-10 and prothrombotic markers was found. Noncomplicated PVVs are associated with systemic, prothrombotic activation of hemostasis and increased concentration of MMP-10, suggesting a prothrombotic and proinflammatory state. © The Author(s) 2014.

Endothelium dysfunction markers in patients with diabetic retinopathy.

PubMed

Siemianowicz, Krzysztof; Francuz, Tomasz; Gminski, Jan; Telega, Alicja; Syzdól, Marcin

2005-03-01

Diabetes mellitus leads to endothelium dysfunction and an accelerated progression of atherosclerosis. Vascular complications of diabetes mellitus can affect not only large and medium arteries resulting in coronary heart disease and peripheral arteries diseases, but also small vessels leading to retinopathy and nephropathy. Intercellular adhesion molecule-1 (ICAM-1), vascular adhesion molecule-1 (VCAM-1), E-selectin and von Willebrand factor (vWF) are considered as markers of endothelium dysfunction. The aim of our study was to evaluate plasma levels of ICAM-1, VCAM-1, E-selectin and vWF in patients with type 2 diabetes mellitus receiving insulin therapy and who had diabetic non-proliferative retinopathy, proliferative retinopathy, or did not develop diabetic retinopathy. There were no statistically significant differences between studied groups in any of evaluated endothelium dysfunction markers. There was no statistically significant correlation between measured parameters and a period of diabetic history. None of the studied markers presented a significant correlation with a period of insulin treatment.

Systemic reactive angioendotheliomatosis-like syndrome in a steer presumed to be persistently infected with bovine viral diarrhea virus.

PubMed

Breshears, M A; Johnson, B J

2008-09-01

Unusual proliferative intravascular lesions were seen in multiple organs of a 2-year-old Corriente steer presumed to be persistently infected with bovine viral diarrhea virus (BVDV), based on widespread immunohistochemical detection of BVDV antigen. Proliferations of spindle cells, which were immunohistochemically positive for von Willebrand factor-related antigen, partially-to-completely occluded vessel lumens and were supported by cells that were immunohistochemically positive for smooth muscle actin. Distribution and character of the intraluminal proliferations are strikingly similar to those described in feline systemic reactive angioendotheliomatosis, a rare entity of unknown cause. The presence of occasional intravascular thrombi suggests that the proliferative vasculopathy was associated with an underlying thrombotic process with immunohistochemical similarities to thrombotic thrombocytopenic purpura of humans. Death of the steer was due to hemorrhage from a castration wound, which may indicate thrombocytopenia or platelet dysfunction. The role of persistent BVDV infection in the formation of the intravascular lesions is unknown.

Elastomeric microvalve geometry affects haemocompatibility.

PubMed

Szydzik, Crispin; Brazilek, Rose J; Khoshmanesh, Khashayar; Akbaridoust, Farzan; Knoerzer, Markus; Thurgood, Peter; Muir, Ineke; Marusic, Ivan; Nandurkar, Harshal; Mitchell, Arnan; Nesbitt, Warwick S

2018-06-12

This paper reports on the parameters that determine the haemocompatibility of elastomeric microvalves for blood handling in microfluidic systems. Using a comprehensive investigation of blood function, we describe a hierarchy of haemocompatibility as a function of microvalve geometry and identify a "normally-closed" v-gate pneumatic microvalve design that minimally affects blood plasma fibrinogen and von Willebrand factor composition, minimises effects on erythrocyte structure and function, and limits effects on platelet activation and aggregation, while facilitating rapid switching control for blood sample delivery. We propose that the haemodynamic profile of valve gate geometries is a significant determinant of platelet-dependent biofouling and haemocompatibility. Overall our findings suggest that modification of microvalve gate geometry and consequently haemodynamic profile can improve haemocompatibility, while minimising the requirement for chemical or protein modification of microfluidic surfaces. This biological insight and approach may be harnessed to inform future haemocompatible microfluidic valve and component design, and is an advance towards lab-on-chip automation for blood based diagnostic systems.

Acquired thrombotic thrombocytopenic purpura: new therapeutic options and their optimal use.

PubMed

Cataland, S R; Wu, H M

2015-06-01

Advances in our understanding of the pathophysiology of both congenital and acquired thrombotic thrombocytopenic purpura (TTP) have led to both an increased understanding of the disease and novel approaches to therapy. The efficacy of rituximab in acquired TTP has led to consideration of rituximab as a prophylactic therapy to prevent relapse of TTP. Novel therapies that target the A1 domain of von Willebrand factor (VWF) to block the formation of microthrombotic disease have also entered clinical study and have demonstrated promise as potential therapeutic options. Additionally, a recombinant ADAMTS13 protease has been developed which may be an important therapeutic option for both congenital and acquired TTP. The development of these new therapeutic options for patients diagnosed with TTP has increased the importance of conducting prospective, randomized studies with these agents to both confirm their efficacy and more importantly understand their most appropriate role in the treatment of patients with TTP. © 2015 International Society on Thrombosis and Haemostasis.

Thrombus Formation at High Shear Rates.

PubMed

Casa, Lauren D C; Ku, David N

2017-06-21

The final common pathway in myocardial infarction and ischemic stroke is occlusion of blood flow from a thrombus forming under high shear rates in arteries. A high-shear thrombus forms rapidly and is distinct from the slow formation of coagulation that occurs in stagnant blood. Thrombosis at high shear rates depends primarily on the long protein von Willebrand factor (vWF) and platelets, with hemodynamics playing an important role in each stage of thrombus formation, including vWF binding, platelet adhesion, platelet activation, and rapid thrombus growth. The prediction of high-shear thrombosis is a major area of biofluid mechanics in which point-of-care testing and computational modeling are promising future directions for clinically relevant research. Further research in this area will enable identification of patients at high risk for arterial thrombosis, improve prevention and treatment based on shear-dependent biological mechanisms, and improve blood-contacting device design to reduce thrombosis risk.

Immunohistochemical Analysis of the Role of Hemocytin in Nodule Formation in the Larvae of the Silkworm, Bombyx mori

PubMed Central

Arai, Ikuyo; Ohta, Masayuki; Suzuki, Asahi; Tanaka, Shiho; Yoshizawa, Yasutaka; Sato, Ryoichi

2013-01-01

Hemocytin, a multidomain protein from Bombyx mori L. (Lepidoptera: Bombycidae), is an ortholog of von Willebrand factor and is expected to be a major mediator of hemocyte aggregation. Antiserum was generated against hemocytin, and immune staining of hemocytes, hemolymph, and nodules was performed. Hemocytin was observed in steady-state hemocytes but not in plasma, even after bacterial injection. When hemolymph was smeared on glass slides, hemocytin-containing fibrous structures formed a cellular network mainly consisting of granulocytes and oenocytoids. Hemocytin was stained only in the granules of the granulocytes. When nodule-like aggregates formed 30 sec after bacterial injection, both granulocytes and bacterial cells were observed binding to hemocytin-containing fibrous structures. When nodule sections were stained with antiserum, hemocytin was seen in the matrix of the nodules surrounding the hemocytes. These data suggest that hemocytin plays a major role in nodule formation as a component of the sticky fibrous structure exocytosed from granulocytes. PMID:24766322

Subcutaneous Soft Tissue Sarcoma with Rhabdoid Features in a Dog

PubMed Central

Sayama, Ayako; Okado, Keiko; Imaoka, Masako; Yokouchi, Yusuke; Jindo, Toshimasa; Takasaki, Wataru

2014-01-01

A nine-year-old male beagle dog had a white spherical mass in the subcutis of the left lumbar region. Microscopically, spindle to oval cells diffusely proliferated in the fibrous and myxoid stroma. Many neoplastic cells showed rhabdoid features or vacuolated cytoplasm. Immunohistochemically, the neoplastic cells were positive for vimentin and S100 and partly positive for neuron-specific enolase and glial fibrillary acidic protein but were negative for von Willebrand factor, desmin and α-smooth muscle actin. Ultrastructurally, the neoplastic cells had abundant cytoplasmic processes and desmosome-like structures. Cytoplasmic inclusions of rhabdoid-featured cells in HE sections were composed of aggregates of intermediate filaments, and cytoplasmic vacuoles were identified as an invagination of cytoplasm. Although malignant peripheral nerve sheath tumor was suggested according to these results, the present case was diagnosed as a soft tissue sarcoma with rhabdoid features due to a lack of identification of the basal lamina under electron microscopy. PMID:25352714

Neuropathy in non-freezing cold injury (trench foot).

PubMed Central

Irwin, M S; Sanders, R; Green, C J; Terenghi, G

1997-01-01

Non-freezing cold injury (trench foot) is characterized, in severe cases, by peripheral nerve damage and tissue necrosis. Controversy exists regarding the susceptibility of nerve fibre populations to injury as well as the mechanism of injury. Clinical and histological studies (n = 2) were conducted in a 40-year-old man with severe non-freezing cold injury in both feet. Clinical sensory tests, including two-point discrimination and pressure, vibration and thermal thresholds, indicated damage to large and small diameter nerves. On immunohistochemical assessment, terminal cutaneous nerve fibres within the plantar skin stained much less than in a normal control whereas staining to von Willebrand factor pointed to increased vascularity in all areas. The results indicate that all nerve populations (myelinated and unmyelinated) were damaged, possibly in a cycle of ischaemia and reperfusion. Images Figure 1 a Figure 1 b Figure 2 a Figure 2 b Figure 3 a Figure 3 b PMID:9306996

Subcutaneous soft tissue sarcoma with rhabdoid features in a dog.

PubMed

Sayama, Ayako; Okado, Keiko; Imaoka, Masako; Yokouchi, Yusuke; Jindo, Toshimasa; Takasaki, Wataru

2014-07-01

A nine-year-old male beagle dog had a white spherical mass in the subcutis of the left lumbar region. Microscopically, spindle to oval cells diffusely proliferated in the fibrous and myxoid stroma. Many neoplastic cells showed rhabdoid features or vacuolated cytoplasm. Immunohistochemically, the neoplastic cells were positive for vimentin and S100 and partly positive for neuron-specific enolase and glial fibrillary acidic protein but were negative for von Willebrand factor, desmin and α-smooth muscle actin. Ultrastructurally, the neoplastic cells had abundant cytoplasmic processes and desmosome-like structures. Cytoplasmic inclusions of rhabdoid-featured cells in HE sections were composed of aggregates of intermediate filaments, and cytoplasmic vacuoles were identified as an invagination of cytoplasm. Although malignant peripheral nerve sheath tumor was suggested according to these results, the present case was diagnosed as a soft tissue sarcoma with rhabdoid features due to a lack of identification of the basal lamina under electron microscopy.

Increase in Mechanical Resistance to Force in a Shear-Activated Protein

NASA Astrophysics Data System (ADS)

Botello, Eric; Harris, Nolan; Choi, Huiwan; Zhou, Zhou; Bergeron, Angela; Dong, Jing-Fei; Kiang, Ching-Hwa

2009-03-01

von Willebrand factor (VWF) is the largest multimeric adhesion ligand found in human blood. Plasma VWF (pVWF) must be exposed to shear stress, like at sites of vascular injury, to be activated to bind platelets to induce blood clotting. In addition, adhesion activity of VWF is related to its polymer size, with the ultra-large form of VWF (ULVWF) being hyper-active, and forming fibers even without exposure to shear stress. We used the AFM to stretch pVWF, sheared VWF (sVWF) and ULVWF, and monitor the forces as a function of molecular extension. We showed a similar increase in force resistance to unfolding for sVWF and ULVWF when compared to pVWF. The increase in force is reduced when other molecules that are known to disrupt their fibril formation are present. Our results provide evidence that the common higher order structure of sVWF and ULVWF may affect the domain structure that causes difference in their adhesion activity compared to pVWF.

Fluorescence fluctuation spectroscopy for clinical applications

NASA Astrophysics Data System (ADS)

Olson, Eben

Fluorescence correlation spectroscopy (FCS) and the related techniques of brightness analysis have become standard tools in biological and biophysical research. By analyzing the statistics of fluorescence emitted from a restricted volume, a number of parameters including concentrations, diffusion coefficients and chemical reaction rates can be determined. The single-molecule sensitivity, spectral selectivity, small sample volume and non-perturbative measurement mechanism of FCS make it an excellent technique for the study of molecular interactions. However, its adoption outside of the research laboratory has been limited. Potential reasons for this include the cost and complexity of the required apparatus. In this work, the application of fluorescence fluctuation analysis to several clinical problems is considered. Optical designs for FCS instruments which reduce the cost and increase alignment tolerance are presented. Brightness analysis of heterogenous systems, with application to the characterization of protein aggregates and multimer distributions, is considered. Methods for FCS-based assays of two clinically relevant proteins, von Willebrand factor and haptoglobin, are presented as well.

A Structure of a Collagen VI VWA Domain Displays N and C Termini at Opposite Sides of the Protein

PubMed Central

Becker, Ann-Kathrin A.; Mikolajek, Halina; Paulsson, Mats; Wagener, Raimund; Werner, Jörn M.

2014-01-01

Summary Von Willebrand factor A (VWA) domains are versatile protein interaction domains with N and C termini in close proximity placing spatial constraints on overall protein structure. The 1.2 Å crystal structures of a collagen VI VWA domain and a disease-causing point mutant show C-terminal extensions that place the N and C termini at opposite ends. This allows a “beads-on-a-string” arrangement of multiple VWA domains as observed for ten N-terminal domains of the collagen VI α3 chain. The extension is linked to the core domain by a salt bridge and two hydrophobic patches. Comparison of the wild-type and a muscular dystrophy-associated mutant structure identifies a potential perturbation of a protein interaction interface and indeed, the secretion of mutant collagen VI tetramers is affected. Homology modeling is used to locate a number of disease-associated mutations and analyze their structural impact, which will allow mechanistic analysis of collagen-VI-associated muscular dystrophy phenotypes. PMID:24332716

A Two-Tier Golgi-Based Control of Organelle Size Underpins the Functional Plasticity of Endothelial Cells

PubMed Central

Ferraro, Francesco; Kriston-Vizi, Janos; Metcalf, Daniel J.; Martin-Martin, Belen; Freeman, Jamie; Burden, Jemima J.; Westmoreland, David; Dyer, Clare E.; Knight, Alex E.; Ketteler, Robin; Cutler, Daniel F.

2014-01-01

Summary Weibel-Palade bodies (WPBs), endothelial-specific secretory granules that are central to primary hemostasis and inflammation, occur in dimensions ranging between 0.5 and 5 μm. How their size is determined and whether it has a functional relevance are at present unknown. Here, we provide evidence for a dual role of the Golgi apparatus in controlling the size of these secretory carriers. At the ministack level, cisternae constrain the size of nanostructures (“quanta”) of von Willebrand factor (vWF), the main WPB cargo. The ribbon architecture of the Golgi then allows copackaging of a variable number of vWF quanta within the continuous lumen of the trans-Golgi network, thereby generating organelles of different sizes. Reducing the WPB size abates endothelial cell hemostatic function by drastically diminishing platelet recruitment, but, strikingly, the inflammatory response (the endothelial capacity to engage leukocytes) is unaltered. Size can thus confer functional plasticity to an organelle by differentially affecting its activities. PMID:24794632

Assessment of the Dual Role of Clumping Factor A in S. Aureus Adhesion to Endothelium in Absence and Presence of Plasma.

PubMed

Claes, Jorien; Ditkowski, Bartosz; Liesenborghs, Laurens; Veloso, Tiago Rafael; Entenza, Jose M; Moreillon, Philippe; Vanassche, Thomas; Verhamme, Peter; Hoylaerts, Marc F; Heying, Ruth

2018-06-17

Adhesion of Staphylococcus aureus to endothelial cells (ECs) is paramount in infective endocarditis. Bacterial proteins such as clumping factor A (ClfA) and fibronectin binding protein A (FnbpA) mediate adhesion to EC surface molecules and (sub)endothelial matrix proteins including fibrinogen (Fg), fibrin, fibronectin (Fn) and von Willebrand factor (vWF). We studied the influence of shear flow and plasma on the binding of ClfA and FnbpA (including its sub-domains A, A 16+ , ABC, CD) to coverslip-coated vWF, Fg/fibrin, Fn or confluent ECs, making use of Lactococcus lactis , expressing these adhesins heterologously. Global adherence profiles were similar in static and flow conditions. In the absence of plasma, L. lactis-clfA binding to Fg increased with shear forces, whereas binding to fibrin did not. The degree of adhesion of L. lactis-fnbpA to EC-bound Fn and of L. lactis-clfA to EC-bound Fg, furthermore, was similar to that of L. lactis-clfA to coated vWF domain A1, in the presence of vWF-binding protein (vWbp). Yet, in plasma, L. lactis-clfA adherence to activated EC-vWF/vWbp dropped over 10 minutes by 80% due to vWF-hydrolysis by a disintegrin and metalloproteinase with thrombospondin type 1 motif, member 13 and that of L. lactis-fnbpA likewise by > 70% compared to the adhesion in absence of plasma. In contrast, plasma Fg supported high L. lactis-clfA binding to resting and activated ECs. Or, in plasma S. aureus adhesion to active endothelium occurs mainly via two complementary pathways: a rapid but short-lived vWF/vWbp pathway and a stable integrin-coupled Fg-pathway. Hence, the pharmacological inhibition of ClfA-Fg interactions may constitute a valuable additive treatment in infective endocarditis. Schattauer GmbH Stuttgart.

Virchow's triad: Kussmaul, Quincke and von Recklinghausen.

PubMed

Stanifer, John W

2016-02-01

For most of the 19th century, Germany was the centre of the medical world. From there the most innovating research came and many of the physicians of that era are known to nearly every medical student and physician of today. Virchow, Kussmaul, Quincke, von Recklinghausen, Müller and Schönlein are familiar names in today's medicine but insofar as they are merely eponyms associated with signs, symptoms, disease and anatomy. The story of their lives, their research and their influence on each other has been little examined. This is an essay about Virchow's relationship with his mentors Müller and Schönlein and how these relationships shaped the development of Kussmaul, Quincke and von Recklinghausen as students of Virchow and their work in medicine and clinical observation after leaving Virchow's laboratory. © The Author(s) 2014.

Von eingebetteten Systemen zu Cyber-Physical Systems

NASA Astrophysics Data System (ADS)

Wedde, Rorst F.; Lehnhoff, Sebastian; Rehtanz, Christian; Krause, Olav

Das Hauptanliegen des Papiers ist, ein Paradigma für Probleme mit neuartigen Integrationsanforderungen für Forschung und Entwicklung in verteilten eingebetteten Echtzeitsystemen zu motivieren und vorzustellen, nämlich den Begriff Cyber-Physical Systems. Bei einer in letzter Zeit stark zunehmenden Anzahl von Realzeitanwendungen können ohne die Berücksichtigung solcher Forderungen keine praktisch brauchbaren Lösungen erwartet werden. Einige Anwendungsfelder werden angesprochen. Im Einzelnen werden dann für Elektroautos, die mit erneuerbaren Energien betrieben werden sollen, einerseits die Management-, verteilte Verhandlungs- und Verteilungsprobleme der benötigten Energie in einem bottom-up Ansatz gelöst. Andererseits wird als Teil unserer Projektarbeit die Bereitstellung von Reserveenergie für den allgemeinen Bedarf durch Autobatterien vorgestellt. Es zeigt sich, dass dies effizienter und wesentlich kurzfristiger in unserem verteilten Vorgehen geschehen kann als in traditionellen Verfahren.

Idiopathic Non-Cirrhotic Intrahepatic Portal Hypertension (NCIPH)—Newer Insights into Pathogenesis and Emerging Newer Treatment Options

PubMed Central

Goel, Ashish; Elias, Joshua E.; Eapen, Chundamannil E.; Ramakrishna, Banumathi; Elias, Elwyn

2014-01-01

Chronic microangiopathy of portal venules results in idiopathic non-cirrhotic intrahepatic portal hypertension (NCIPH). Recent data suggest a role for vasoactive factors of portal venous origin in the pathogenesis of this ‘pure’ vasculopathy of the liver. Enteropathies (often silent), are an important ‘driver’ of this disease. NCIPH is under-recognized and often mis-labeled as cryptogenic cirrhosis. Liver biopsy is needed to prove the diagnosis of NCIPH. In these patients, with advancing disease and increased porto-systemic shunting, the portal venous vasoactive factors bypass the liver filter and contribute to the development of pulmonary vascular endothelial disorders—porto-pulmonary hypertension and hepato-pulmonary syndrome as well as mesangiocapillary glomerulonephritis. Prognosis in NCIPH patients is determined by presence, recognition and management of associated disorders. With better understanding of the pathogenesis of NCIPH, newer treatment options are being explored. Imbalance in ADAMTS 13 (a disintegrin and metalloprotease with thrombospondin type 1 motif, member 13): vWF (von-Willebrand factor) ratio is documented in NCIPH patients and may have a pathogenic role. Therapeutic interventions to correct this imbalance may prove to be important in the management of NCIPH. PMID:25755567

Free radical activity and hemostatic factors in NIDDM patients with and without microalbuminuria.