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Von Willebrand Factor (von + willebrand_factor)
Selected AbstractsA new ELISA assay for diagnosis of acquired von Willebrand SyndromeHAEMOPHILIA, Issue 3 2003C. Siaka Summary. The pathophysiology of acquired von Willebrand syndrome (AVWS), a rare bleeding disorder, is not fully understood. Circulating antibodies to Von Willebrand factor (VWF) are found in patients with AVWS associated with lymphoproliferative disorders but these autoantibodies are difficult to detect with routine laboratory tests and neutralisation assays. We have developed a simple enzyme-linked immunosorbent assay (ELISA) to detect serum antibody binding to VWF protein immobilized on polystyrene plates. Ten patients with AVWS were studied, eight of whom also had lymphoproliferative disorders. We found antibodies in eight patients; all of them were positive for IgG and five were also positive for IgM. This simple method appears to be more sensitive than functional assays, which failed to identify two of the patients who were positive with the ELISA. In conjunction with other tests, this ELISA method may be useful for demonstrating the immunological mechanism underlying some cases of AVWS. Such patients would qualify for intravenous immunoglobulin therapy, which can correct the clotting disorder. [source] Von Willebrand Factor Antigen Concentration in Dogs with SepsisJOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 1 2010C.L. Rogers Background: Von Willebrand factor (vWF) antigen concentration, a marker of endothelial activation, is increased in human patients with multiorgan failure, sepsis, or both, and is an independent predictor of survival. Hypothesis/Objectives: vWF antigen concentrations are significantly higher in dogs with sepsis. Animals: Fourteen dogs hospitalized with sepsis. Sepsis was defined as microbiologic or cytologic evidence of infection combined with systemic inflammatory response syndrome. Control dogs were healthy dogs, without evidence of disease. Methods: Prospective, observational study. Dogs admitted to the intensive care unit with a diagnosis of sepsis were considered eligible for enrollment into the study. Exclusion criteria included a previous diagnosis of von Willebrand disease or a recent history of a plasma transfusion. Citrated plasma samples were collected for analysis of vWF antigen by ELISA. All samples were drawn from dogs during hospitalization. Data between populations were analyzed using nonparametric statistical analysis with a P value < .05 considered significant. Results: Twenty-five dogs were enrolled; 14 dogs with sepsis and 11 control dogs. The median vWF antigen concentration in dogs with sepsis was 156% (range, 117,200%), which was significantly higher than healthy dogs (105%; range, 44,155%, P < .005). There was no difference between survivors and nonsurvivors with a median vWF antigen concentration of 144% (range, 136,201%) in survivors (n = 7) and 159% (range, 122,174%) in nonsurvivors (n = 7) (P= .5). Conclusions and Clinical Importance: vWF is increased in dogs with sepsis, possibly reflecting endothelial activation. Further exploration of endothelial function is warranted in critically ill dogs. [source] Clinical and laboratory diagnosis of von Willebrand disease: A synopsis of the 2008 NHLBI/NIH guidelines,AMERICAN JOURNAL OF HEMATOLOGY, Issue 6 2009William L. Nichols 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). Am. J. Hematol. 2009. © 2009 Wiley-Liss, Inc. [source] Von Willebrand factor protects the Ca2+ -dependent structure of the factor VIII light chainBRITISH JOURNAL OF HAEMATOLOGY, Issue 5 2009Masahiro Takeyama Summary We have recently reported that cation-exchange iminodiacetate resin completely inactivated factor VIII (FVIII) by direct deprivation of metal ions, predominantly Ca2+, from its molecules, and that von Willebrand factor (VWF) protected FVIII antigen from resin-induced degradation. The present study was further developed to investigate this mechanism. Western blotting analysis and enzyme-linked immunosorbent assay showed that the antigenic structure of the FVIII light chain, especially the C2 domain, was completely impaired by the resin, whilst that of the heavy chain was little affected. However, the complex formation with VWF protected the C2 domain from the resin-induced degradation. The resin-treated C2 domain failed to interact with VWF and phospholipid. Furthermore, the addition of Ca2+ competitively blocked the resin-induced impairment of the C2 domain structure. These results demonstrate that VWF protects the Ca2+ -dependent conformational structure of the FVIII light chain, especially the C2 domain, and may indicate that the C2 domain contains the Ca2+ -binding site(s). [source] Endothelial markers in chronic heart failure: training normalizes exercise-induced vWF releaseEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 9 2004L. W. E. Sabelis Abstract Background, Chronic heart failure (CHF) is characterized by endothelial dysfunction. Vascular endothelium is important for control of haemostasis and vasoregulation. The aim of the present study was to investigate plasma levels of several endothelial markers and the exercise-induced changes on these plasma levels in CHF patients. Subsequently, the effect of a 6-month training programme on these markers is described. Materials and methods, Twenty-nine male CHF patients (NYHA II/III, age 60 ± 8 year, body mass index 26·7 ± 2·3 kg m,2, left ventricular ejection fraction 26·3,7·2%; mean ± SD) participated. Patients were randomly assigned to a training or control group. Training (26 weeks; combined strength and endurance exercises) was four sessions/week: two sessions supervised and two sessions at home. Before and after intervention, anthropometry, endothelial markers (haemostasis and vasoregulation), maximal workload and peak oxygen uptake were assessed. Results, Physical training positively affected maximal workload. Plasma levels of endothelial markers were not affected by physical training and not related to exercise tolerance. After training, stimulated (maximal exercise) plasma von Willebrand Factor (vWF) release was present, whereas at baseline this release was absent. Conclusion, Physical training led to normalization of the stimulated plasma vWF release. Plasma levels of other endothelial markers were not affected by physical training either at rest or under stimulated (maximal exercise) conditions. [source] Factor VIII and von Willebrand factor interaction: biological, clinical and therapeutic importanceHAEMOPHILIA, Issue 1 2010V. TERRAUBE Summary., The interaction of factor VIII (FVIII) with von Willebrand Factor (VWF) is of direct clinical significance in the diagnosis and treatment of patients with haemophilia A and von Willebrand disease (VWD). A normal haemostatic response to vascular injury requires both FVIII and VWF. It is well-established that in addition to its role in mediating platelet to platelet and platelet to matrix binding, VWF has a direct role in thrombin and fibrin generation by acting as a carrier molecule for the cofactor FVIII. Recent studies show that the interaction affects not only the biology of both FVIII and VWF, and the pathology of haemophilia and VWD, but also presents opportunities in the treatment of haemophilia. This review details the mechanisms and the molecular determinants of FVIII interaction with VWF, and the role of FVIII,VWF interaction in modulating FVIII interactions with other proteases, cell types and cellular receptors. The effect of defective interaction of FVIII with VWF as a result of mutations in either protein is discussed. [source] Improved performance characteristics of the von Willebrand factor ristocetin cofactor activity assay using a novel automated assay protocolJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 10 2010A. HILLARP Summary.,Background, objectives and methods:,An accurate, sensitive and precise assay for reliable determination of the ristocetin cofactor activity of von Willebrand factor (VWF:RCo) in plasma and von Willebrand Factor (VWF)-containing concentrates has been evaluated. The assay is based on a commercially available automated protocol with modifications including a combination of adding additional ristocetin and the use of two calibration curves for the high and low measuring ranges. Results:,Addition of extra ristocetin resulted in improved measurement of VWF recoveries from various VWF-containing concentrates that were underestimated using the standard automated protocol. The modifications resulted in improved assay performance over an extended measuring range (2.00,0.03 IU mL,1). Accuracy was tested using VWF deficiency plasma spiked with the 1st international standard (IS) for VWF concentrate. Seven dilutions, ranging from 1.80 to 0.05 IU mL,1, were analyzed and resulted in measured concentrations between 80% and 100% of the assigned potency of the standard. Linearity was determined from the regression plot of the same concentrate dilutions and resulted in a correlation coefficient of 0.998. The repeatability, expressed as coefficient of variation, was 2% in the normal range (0.90 IU mL,1) and 8% at the level of 0.05 IU mL,1. The corresponding reproducibility results were 2% and 15% at the normal and low measuring ranges, respectively. Conclusions:,Analysis of patients with von Willebrand disease (VWD) indicates that the modified automated BCS® protocol has a superior discrimination power compared with the standard protocol. This is especially true in samples with low VWF, as in patients with type 3 VWD. [source] A method for the isolation of glomerular and tubulointerstitial endothelial cells and a comparison of characteristics with the human umbilical vein endothelial cell modelNEPHROLOGY, Issue 4 2004STELLA MCGINN SUMMARY: Background: Abnormalities in the structure and function of glomerular endothelial cells play a pivotal role in the development of progressive renal disease. The vascular abnormalities observed in the renal tubulointerstitium, however, correlate more strongly with progressive renal failure. Therefore, the successful isolation and culture of human renal microvascular endothelial cells from both the glomerulus and tubulointerstitium are paramount in studying renal disease models. Methods and Results: This study describes a simple and reproducible method for the isolation of human tubulointerstitial and glomerular endothelial cells by using immunomagnetic separation with anti-platelet endothelial-cell adhesion (anti-PECAM-1) Dyna beads, followed by manual weeding of mesangial and fibroblast contamination. No significant changes in morphological or immunohistochemical characteristics were observed up to passage two of culture. The in vitro characteristics of the endothelial cells were compared to the renal cortical endothelial cells in vivo and the standard human umbilical vein endothelial cell model (HUVECs). Similar to HUVECs, both populations of renal microvascular endothelial cells had a classical cobblestone appearance, stained positively for von Willebrand Factor and PECAM-1 and negatively for antifibroblast surface antigen and anticytokeratin. Differences in the expression of von Willebrand Factor, Wiebel Palade bodies and Flk-1 staining were observed between glomerular and tubulointerstitial endothelial cells. These immunohistochemical characteristics suggested that tubulointerstital endothelial cells were more closely aligned to HUVECS than to the glomerular endothelial cells. This observation indicated that HUVECs may be a suitable model for determining the tubulointerstitial endothelial response to systemic injury. Conclusion: In conclusion, a unique and novel method for the differential isolation of both glomerular and tubulointerstitial endothelial cells has been developed. Significantly, characterization of these populations suggests a role for HUVECS in the study of renal tubulointerstitial disease. [source] Fibroblast Growth Factor 2 Promotes Endothelial Differentiation of Adipose Tissue-Derived Stem CellsTHE JOURNAL OF SEXUAL MEDICINE, Issue 4 2009Hongxiu Ning PhD ABSTRACT Introduction., Adipose tissue-derived stem cells (ADSC) could potentially restore endothelial function in vasculogenic erectile dysfunction (ED). The mechanism for ADSC endothelial differentiation remained unidentified. Aim., To test whether ADSC could differentiate into endothelial cells in the penis and to identify the underlying mechanism of ADSC endothelial differentiation. Methods., For in vivo endothelial differentiation, ADSC were labeled with bromodeoxyuridine (BrdU), injected into rat corpora cavernosa, and localized by immunofluorescence and phase-contrast microscopy. For in vitro endothelial differentiation, ADSC were grown in endothelial growth medium 2 (EGM2), stained for endothelial markers CD31, von Willebrand Factor (vWF), and endothelial nitric oxide synthase (eNOS), and assessed for the ability to form tube-like structures in Matrigel and to endocytose acetylated low-density lipoprotein (Ac-LDL). To identify factors that promote ADSC endothelial differentiation, ADSC were grown in various media, each of which contained a specific combination of supplemental factors and assessed for LDL-uptake. PD173074, a selective inhibitor of fibroblast growth factor 2 (FGF2) receptor, was used to confirm the importance of FGF2 signaling for ADSC endothelial differentiation. Main Outcome Measures., In vivo endothelial differentiation was assessed by immunofluorescence microscopy. In vitro endothelial differentiation was assessed by immunofluorescence, Matrigel tube formation, and Ac-LDL uptake. Results., Injected ADSC were localized to the sinusoid endothelium, some of which stained positive for both BrdU and endothelial antigen rat endothelial cell antigen. ADSC proliferated at a faster rate in EGM2 than in standard DMEM, expressed endothelial markers CD31, vWF, and eNOS, formed tube-like structures in Matrigel, and endocytosed Ac-LDL. These properties were greatly diminished when ADSC were grown in the absence of FGF2 but were unaffected when grown in the absence of vascular endothelial growth factor, insulin-like growth factor, or epidermal growth factor. Furthermore, ADSC displayed similar endothelial properties when grown in FGF2-supplemented basic medium as in EGM2. Finally, blockade of FGF2 signaling with PD173074 abrogated ADSC endothelial differentiation. Conclusions., ADSC could differentiate into endothelial cells in the penis. FGF2 signaling mediates ADSC endothelial differentiation. Ning H, Liu G, Lin G, Yang R, Lue TF, and Lin CS. FGF2 promotes endothelial differentiation of adipose tissue-derived stem cells. J Sex Med **;**:**,**. [source] Venous thrombosis of the upper extremity: effect of blood group and coagulation factor levels on riskBRITISH JOURNAL OF HAEMATOLOGY, Issue 1 2010Linda E. Flinterman Summary Venous thrombosis of the upper extremity is a rare form of thrombosis, accounting for around 4% of all venous thromboses, and for which only a few risk factors are known. This case-control study investigated the effect of coagulation factors on risk of venous thrombosis of the upper extremity. Patients with venous thrombosis of the arm and partner controls were selected from the Multiple Environmental and Genetic Assessment study, a large population-based case-control study. Participants with a malignancy were excluded. Odds ratios (OR) were estimated for elevated levels of factor II, VII, VIII, IX, X, XI, von Willebrand Factor (VWF), and fibrinogen, low levels of protein C, protein S, and antithrombin, and for blood group non-O. Substantially increased risks of venous thrombosis of the upper extremity were found for patients with high levels (above 90th percentile versus below) of factor VIII (OR: 4·2, 95% confidence interval (CI): 2·2,7·9), VWF (OR: 4·0, 95% CI: 2·1,7·8), fibrinogen (OR: 2·9, 95% CI, 1·5,5·7), and for blood group non-O compared to O (OR: 2·1, 95% CI, 1·3,3·6). The other factors were not associated with an increased risk. Elevated levels of several procoagulant factors are associated with a strongly increased risk of venous thrombosis of the upper extremity. [source] Perioperative Management of von Willebrand Disease in Dermatologic SurgeryDERMATOLOGIC SURGERY, Issue 4 2007AIMEE L. LEONARD MD BACKGROUND Von Willebrand disease (VWD) is the most common inherited bleeding disorder, affecting an estimated 0.1% to 1% of the population. It is caused by a qualitative or quantitative defect of von Willebrand factor. Primary manifestations include intractable mucocutaneous bleeding after surgery or trauma. OBJECTIVE The objective was to review the pathophysiology and clinical features of VWD and to propose a perioperative management strategy for patients with this condition undergoing dermatologic surgery. METHODS AND MATERIALS Literature is reviewed. RESULTS The various types and clinical manifestations of this condition are reviewed, and a perioperative strategy is presented for managing patients with VWD who undergo cutaneous oncologic or cosmetic surgical procedures. CONCLUSIONS In most cases, dermatologic surgery can be safely performed in patients with VWD. The use of appropriate therapeutic prophylaxis in conjunction with a hematologist is indicated in high-risk, nonelective procedures. [source] Prognostic value of interleukin-6, plasma viscosity, fibrinogen, von Willebrand factor, tissue factor and vascular endothelial growth factor levels in congestive heart failureEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 11 2003B. S. P. Chin Abstract Background, Congestive heart failure (CHF) carries a poor prognosis with a high mortality rate, frequent hospitalizations and increased risk of thrombotic complications such as stroke. Cytokines may contribute to the progression and prothrombotic state of CHF, including the pro-inflammatory interleukin-6 (IL-6) and the pro-angiogenic vascular endothelial growth factor (VEGF), both of which are raised in CHF. The procoagulant properties of both cytokines may be mediated via tissue factor (TF), a potent clotting activator. We hypothesized that plasma levels of these markers, as well as levels of plasma viscosity, fibrinogen, soluble P-selectin and von Willebrand factor (markers of abnormal rheology, clotting, platelet activation, and endothelial damage, respectively) will be useful in predicting morbidity and mortality in chronic stable CHF. Methods and results, One hundred and twenty consecutive out-patients with chronic stable CHF (92 males; mean [SD] age 64 [11] years, mean [SD] left ventricular ejection fraction of 29 [6]%) were recruited and followed for 2 years during which 42 patients reached a clinical end-point of all-cause mortality and cardiovascular hospitalizations, including stroke and myocardial infarction. Plasma IL-6 (P = 0·003) and TF (P = 0·013) levels, but not other research indices, were higher in those who suffered events compared with those without events. Predictors of end-points were high (, median) TF (P = 0·011), and IL-6 (P = 0·023) levels, as well as the lowest quartile of a left ventricular ejection fraction (P = 0·007). A strong correlation was present between TF and IL-6 levels (r = 0·59; P < 0·0001) and with VEGF levels (r = 0·43; P < 0·0001). Conclusion, IL-6 and TF are predictors of poor prognosis in chronic CHF, raising the hypothesis that IL-6 may contribute to the progression and thrombotic complications of CHF via its actions on TF expression. Although VEGF did not independently predict outcome in chronic CHF, the possibility arises that it may act with IL-6 to induce TF expression. [source] Procoagulant factors and the risk of myocardial infarction in young womenEUROPEAN JOURNAL OF HAEMATOLOGY, Issue 1 2006Bea Tanis Abstract:,Objectives:,We investigated whether elevated levels of factor VIII, IX and XI is associated with myocardial infarction (MI) in young women. In addition, we studied ABO blood group, von Willebrand factor (VWF) and C-reactive protein (CRP). Methods and results:,We compared 200 women with MI before age 49 years with 626 controls from a population-based case,control study. Mean levels of factor VIII activity (VIII), von Willebrand factor antigen (VWF), factor IX activity (IX) were higher in patients (133, 134 and 132 IU/dL) than in controls (111, 107 and 120 IU/dL, respectively). Mean levels of factor XI (XI) were equal in patients (114 IU/dL) and controls (113 IU/dL). The odds ratio (OR) for MI for blood group non-O vs. O was 1.6 [95% confidence interval (CI) 1.1,2.3]. The OR adjusted for age, index year and area of residence for the highest quartile >150 IU/dL of factor VIII was 2.7 (95% CI 1.6,4.6), of VWF 4.7 (95% CI 2.3,9.7), of factor IX 2.6 (95% CI 1.3,5.4) and of factor XI 0.9 (95% CI 0.5,1.4), all compared with the lowest quartile <100 IU/dL. Conclusions:,Non-O blood group, high VWF, factor VIII and factor IX levels are associated with an increased risk of MI in young women, while high factor XI levels are not. [source] CD34+ cells derived from fetal liver contained a high proportion of immature megakaryocytic progenitor cellsEUROPEAN JOURNAL OF HAEMATOLOGY, Issue 5 2000Dong-Chu Ma Abstract: Endoreplication and maturation of the megakaryocyte (MK) may be retarded or delayed during ontogenesis. In this study, CD34+ cells were isolated from both human fetal liver and adult bone marrow and incubated with thrombopoietin (TPO). The cell number, morphological characteristics, platelet-associated antigen phenotype, maturation stage and DNA ploidy of CD41+cells were examined from day 0 to day 12 in culture. 1) TPO stimulated the proliferation of fetal liver (FL)-derived CD34+ cells with a mean 73.14-fold increase of CD41+ cells after 12 d in culture. Adult BM-derived CD34+ cells increased only slightly, with a mean 8.18-fold increase of CD41+ cells. 2) Although the membrane phenotype of both FL CD34+ -derived MKs and BM CD34+ -derived MKs analyzed with CD41a, CD42a, CD61 and CD34 were similar, all FL CD34+ -derived MKs were in maturation stage I and II and in low ploidy (<4N) class. By comparison, BM CD34+ MKs possessed 15% MKs in maturation stage III and IV and with 23% MKs in high ploidy class (>4N). 3) Most of cultured FL-derived CD34+ cells did not have a well developed demarcation system (DM) and numerous ,-granules after 12 d incubation. von Willebrand factor (vWF) appeared earlier on the cultured BM-derived CD34+ cells than on FL-derived CD34+ cells. 4) The expression of both cyclin E and cyclin B1 progressively increased in FL CD34+cells induced by TPO during 12 d in culture. 5) The expression of cyclin D1 gradually decreased in FL CD34+cells induced by TPO over 12 d incubation. 6) Immunocytochemical analysis showed that cyclin D3 was detected only in cytoplasm of cultured FL-derived CD34+ cells, whereas in both cytoplasm and nuclei of cultured BM-derived CD34+ cells. These data suggest that FL-derived CD34+ cells contain a high proportion of immature megakaryocytic progenitor cells. It further suggests that TPO can push these progenitor cells into proliferation by upregulating the expression of cyclins B1 and E, and drive a high proportion of cells into megakaryocytic lineage. [source] Absence of lymphatic vessels in human dental pulp: a morphological studyEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 2 2010Renato Gerli Gerli R, Secciani I, Sozio F, Rossi A, Weber E, Lorenzini G. Absence of lymphatic vessels in human dental pulp: a morphological study. Eur J Oral Sci 2010; 118: 110,117. © 2010 The Authors. Journal compilation © 2010 Eur J Oral Sci Few and controversial data are available in the literature regarding the presence of lymphatic vessels in the human dental pulp. The present study was designed to examine morphologically the existence of a lymph drainage system in human dental pulp. Human dental pulp and skin sections were immunohistochemically stained with specific antibodies for lymphatic endothelium (D2-40, LYVE-1, VEGFR-3 [vascular endothelial growth factor receptor-3], and Prox-1), with the pan-endothelial markers CD31 and von Willebrand factor (vWF), and with the blood-specific marker CD34. Several blood vessels were identified in human pulps and skin. Lymphatic vessels were found in all human skin samples but in none of the pulps examined. Western blotting performed on human dermis and on pulps treated with collagenase (to remove odontoblasts) confirmed these results. Transmission electron microscopy indicated that vessels which, by light microscopy, appeared to be initial lymphatic vessels had no anchoring filaments or discontinuous basement membrane, both of which are typical ultrastructural characteristics of lymphatic vessels. These results suggest that under normal conditions human dental pulp does not contain true lymphatic vessels. The various theories about dental pulp interstitial fluid circulation should be revised accordingly. [source] Aegyptin displays high-affinity for the von Willebrand factor binding site (RGQOGVMGF) in collagen and inhibits carotid thrombus formation in vivoFEBS JOURNAL, Issue 2 2010Eric Calvo Aegyptin is a 30 kDa mosquito salivary gland protein that binds to collagen and inhibits platelet aggregation. We have studied the biophysical properties of aegyptin and its mechanism of action. Light-scattering plot showed that aegyptin has an elongated monomeric form, which explains the apparent molecular mass of 110 kDa estimated by gel-filtration chromatography. Surface plasmon resonance identified the sequence RGQOGVMGF (where O is hydroxyproline) that mediates collagen interaction with von Willebrand factor (vWF) as a high-affinity binding site for aegyptin, with a KD of approximately 5 nm. Additionally, aegyptin interacts with the linear peptide RGQPGVMGF and heat-denatured collagen, indicating that the triple helix and hydroxyproline are not a prerequisite for binding. However, aegyptin does not interact with scrambled RGQPGVMGF peptide. Aegyptin also recognizes the peptides (GPO)10 and GFOGER with low affinity (,m range), which respectively represent glycoprotein VI and integrin ,2,1 binding sites in collagen. Truncated forms of aegyptin were engineered, and the C-terminus fragment was shown to interact with collagen and to attenuate platelet aggregation. In addition, aegyptin prevents laser-induced carotid thrombus formation in the presence of Rose Bengal in vivo, without significant bleeding in rats. In conclusion, aegyptin interacts with distinct binding sites in collagen, and is useful tool to inhibit platelet,collagen interaction in vitro and in vivo. Structured digital abstract ,,MINT-7299280, MINT-7299290: Collagen (uniprotkb:P02461) binds (MI:0407) to Aegyptin (uniprotkb:O01949) by enzyme linked immunosorbent assay (MI:0411) ,,MINT-7298991, MINT-7299153, MINT-7299208: Collagen (uniprotkb:P02452) binds (MI:0407) to Aegyptin (uniprotkb:O01949) by surface plasmon resonance (MI:0107) ,,MINT-7299266: Collagen (uniprotkb:P02452) binds (MI:0407) to Aegyptin (uniprotkb:O01949) by fluorescence microscopy (MI:0416) ,,MINT-7299256: Collagen (uniprotkb:P02452) binds (MI:0407) to Aegyptin (uniprotkb:O01949) by solid phase assay (MI:0892) [source] Astrocyte and endothelial cell expression of ADAM 17 (TACE) in adult human CNSGLIA, Issue 4 2001Diane R. Goddard Abstract ADAM 17, also known as TACE, is an important sheddase for a number of proteins, including tumor necrosis factor-, (TNF-,), transforming growth factor-, (TGF-,), L-selectin, p75, and p55 TNF receptors, and interleukin-1 receptor II (IL-1RII). The presence of ADAM 17 mRNA in adult mouse and rat CNS was recently reported (Karkkainen et al. Mol Cell Neurosci 15:547,560, 2000). However, the cellular origin of ADAM 17 remains unknown. In this study, we have used an anti-ADAM 17 antibody in an immunohistochemical study of its distribution in human adult CNS tissue. Cells with astrocytic and endothelial morphology were ADAM 17-positive. This finding was further confirmed using double immunofluorescence with antibodies against GFAP and von Willebrand factor, which label astrocytes and endothelial cells, respectively. This study demonstrates that ADAM 17 is expressed by astrocytes and endothelial cells in normal brain tissue and may have a role in normal brain function. GLIA 34:267,271, 2001. © 2001 Wiley-Liss, Inc. [source] Properties of a concentrated minipool solvent-detergent treated cryoprecipitate processed in single-use bag systemsHAEMOPHILIA, Issue 5 2008T. BURNOUF Summary., Cryoprecipitate is still used to treat factor VIII (FVIII), von Willebrand factor (VWF) and/or fibrinogen deficiency. Recently a solvent-detergent (S/D) process of minipools of cryoprecipitate performed in a closed bag system has been designed to improve its viral safety. Still, cryoprecipitate has other drawbacks, including low concentration in active proteins, and presence of haemolytic isoagglutinins. We report here the biochemical evaluation of S/D-treated minipools of cryoprecipitates depleted of cryo-poor plasma. Cryoprecipitates were solubilized by 8 mL of a sterile glucose/saline solution, pooled in batches of 40 donations and subjected to S/D treatment in a plastic bag system using either 2% TnBP or 1% TnBP-1%Triton X-45, followed by oil extractions (n = 10). Mean (±SD) FVIII and fibrinogen content was 8.86 (±1.29) IU mL,1 and 16.02 (±1.98) mg mL,1, and 8.92 (±1.05) IU mL,1 in cryoprecipitate minipools treated with 2% TnBP, and 17.26 (±1.71) mg mL,1, in those treated by TnBP-Triton X-45, respectively. The WWF antigen, ristocetin cofactor and collagen binding activities were close to 10, 7 and 8 IU mL,1, respectively, and were not affected by either SD treatment. VWF multimeric pattern of SD-treated cryoprecipitates were similar to that of normal plasma, and the >15 mers and >10 mers content was identical to that of the starting cryoprecipitates. The anti-A and anti-B titre was 0,1 and 0,1/8, respectively. Therefore, it is possible to prepare virally inactivated cryoprecipitate minipools depleted of isoagglutinins and enriched in functional FVIII, VWF and clottable fibrinogen. [source] The molecular analysis of von Willebrand disease: a guideline from the UK Haemophilia Centre Doctors' Organisation Haemophilia Genetics Laboratory NetworkHAEMOPHILIA, Issue 5 2008S. KEENEY Summary., von Willebrand disease (VWD) is a common autosomally inherited bleeding disorder associated with mucosal or trauma-related bleeding in affected individuals. VWD results from a quantitative or qualitative deficiency of von Willebrand factor (VWF), a glycoprotein that is essential for primary haemostasis and that carries and protects coagulation factor VIII (FVIII) in the circulation. Through characterization of the phenotype and identification of mutations in the VWF gene in patients with VWD, understanding of the genetics and biochemistry of VWF and VWD has advanced considerably. The importance of specific regions of VWF for its interaction with other components of the vasculature has been revealed, and this has facilitated the formal classification of VWD into three subtypes based upon quantitative (types 1 and 3) and qualitative (type 2) deficiency of VWF. The underlying genetic lesions and associated molecular pathology have been identified in many cases of the qualitative type 2 VWD variants (2A, 2B, 2M, 2N) and in the severe quantitative deficiency, type 3 VWD. However in the partial quantitative deficiency, type 1 VWD, the picture is less clear: there is a variable relationship between plasma levels of VWF and bleeding, there is incomplete penetrance and variable expressivity within affected families, the causative molecular defect is unknown in a substantial number of cases, and even in those cases where the causative mutation is known, the associated molecular pathology is not necessarily understood. This guideline aims to provide a framework for best laboratory practice for the genetic diagnosis of VWD, based upon current knowledge and understanding. [source] Type 1 von Willebrand disease: application of emerging data to clinical practiceHAEMOPHILIA, Issue 4 2008P. W. COLLINS Summary., There has been much recent data published on type 1 von Willebrand disease (VWD) predominantly from three multi-centre cohort studies. These data have influenced a revision of the classification of type 1 VWD and have important implications for the management of this disorder. Patients with low von Willebrand factor (VWF) levels tend to have VWF mutations and VWD is transmitted predictably within families. In patients with VWF levels close to the lower end of the normal range, candidate mutations are found less often, ABO blood group is a more important factor and the disease has variable heritability within families. The importance of bleeding symptoms, in addition to VWF levels, in the diagnosis of type 1 VWD has been highlighted. [source] Hypothyroidism and acquired von Willebrand's syndrome: a systematic reviewHAEMOPHILIA, Issue 3 2008E. MANFREDI Summary., Acquired von Willebrand's syndrome type I is the supposed main underlying cause of bleeding tendency in hypothyroid patients. The purpose of this systematic review was to summarize the published evidence on the association between hypothyroidism and acquired von Willebrand's syndrome. All published clinical epidemiological and interventional studies, case reports and in vitro studies that investigated the association between hypothyroidism and acquired von Willebrand's syndrome were identified by a computer-assisted search of the MEDLINE and EMBASE electronic databases. A quality assessment was performed for clinical epidemiological studies. A total of 41 papers were included. A total of 22 epidemiological in vivo studies, two in vitro studies and 47 case reports were finally analyzed. No high quality in vivo study was identified. Almost all bleeding episodes described in the case reports were mucocutaneous. von Willebrand factor (VWF) antigen value was available for 23 patients: median value 28 U/dL (range: 4,45); VWF activity was available for 24 patients: median value 28.5 U/dL (range: <3,55); factor VIII activity was available for 16 patients: median value 47 U/dL (range: 9,74). Acquired von Willebrand's syndrome may be the main factor responsible for bleeding diathesis in overt hypothyroid patients. Even if bleeding episodes are mainly mild and mucocutaneous, blood transfusion, drug administration or surgical procedure may be required. [source] C1584 in von Willebrand factor is necessary for enhanced proteolysis by ADAMTS13 in vitroHAEMOPHILIA, Issue 4 2007S. KEENEY Summary., The cysteine variant of the amino acid change tyrosine/cysteine 1584 (Y/C1584) in von Willebrand factor (VWF) has previously been shown to cosegregate with increased susceptibility of VWF to proteolysis by ADAMTS13. It is not known whether C1584 itself confers increased proteolysis or is linked to a causative change elsewhere in VWF. To address whether C1584 underlies enhanced susceptibility of VWF to ADAMTS13-mediated proteolysis, a single family comprising two heterozygous Y/C1584 individuals and four homozygous Y/Y1584 individuals was investigated. The essential regions of the VWF gene were sequenced in all six individuals and ADAMTS13-mediated proteolysis of plasma VWF was assessed for each individual. Comparison of the VWF coding sequences for the Y/C1584 individuals with those for the Y/Y1584 individuals revealed that two amino acid variants were unique to the heterozygotes: R484 and C1584. The plasma VWF of the two heterozygotes showed increased susceptibility to proteolysis in vitro compared with that of the four homozygotes. In the present study we demonstrate that R484, in the absence of C1584, does not influence VWF proteolysis. Enhanced proteolysis occurred only in the presence of Cys1584. Thus, Cys1584 is necessary for increased susceptibility of VWF to proteolysis by ADAMTS13. [source] Evaluation of pharmacokinetics, efficacy and safety of Immunate® solvent detergent in previously treated patients with severe haemophilia AHAEMOPHILIA, Issue 1 2007L. NEMES Summary., Immunate® Solvent Detergent (S/D) is a plasma derived, purified, human factor VIII (FVIII) , von Willebrand factor (VWF) complex subjected to two virus inactivation/removal processes: S/D and vapor heat treatment. This prospective, multicentre, three-part clinical study evaluated the pharmacokinetics (in comparison to the predecessor product Immunate®), efficacy and safety of Immunate® S/D in 56 previously treated patients with severe haemophilia A. Subjects received Immunate® S/D on-demand, as a prophylactic regimen or both. The results of the pharmacokinetic population demonstrate that Immunate® and Immunate® S/D were equivalent with respect to the FVIII , and to the retrospectively VWF , parameters assessed. A total of 623 bleeding episodes were reported in 47/56 subjects. The duration of prophylaxis ranged from 0.1--5.2 months with a total of 175.6 months. The median number of bleeds per month in subjects on prophylaxis was 0 (range 0--10). Ninety-six percent of bleeding episodes were rated as having an excellent or good response. For most bleeding episodes (89%), subjects required only one infusion with a mean dose of 29.6 IU kg,1. No FVIII inhibitory antibodies were observed in any subject. No related serious adverse events were reported. Thus, the introduction of S/D treatment did not alter the PK characteristics and function of VWF and FVIII molecules of Immunate® S/D which is effective and safe for treatment of bleeding episodes, management of surgical procedures, and prophylaxis. [source] The 80th anniversary of von Willebrand's disease: history, management and researchHAEMOPHILIA, Issue 6 2006A. B. FEDERICI Summary., The history of von Willebrand's disease (VWD) is fascinating because it demonstrates how good clinical observations, genetic studies and biochemical skills can improve basic understanding of a disease and its management. The continuous efforts of scientists and clinicians during the last 80 years have significantly improved the knowledge of von Willebrand factor (VWF) structure and function and the management of VWD. Diagnosis of phenotype and genotype is now available in many countries and treatment is becoming more specific according to the VWD type. Any therapeutic agents must correct the dual defect of haemostasis, i.e. the abnormal platelet adhesion due to reduced and/or dysfunctional and low levels of factor VIII (FVIII) associated with VWF defects. Desmopressin (DDAVP) is the treatment of choice for type 1 VWD because it induces release of VWF from cellular compartments. Plasma virally inactivated VWF concentrates containing FVIII are effective and safe in patients unresponsive to DDAVP. There are advanced plans to develop a recombinant VWF but this product will require the concomitant administration of FVIII for the control of acute bleeds. Basic research studies on cellular biology, biochemistry and immunology have confirmed the role of VWF as a crucial participant in both haemostasis and thrombosis as its main biological activity is to support platelet adhesion,aggregation in the circulation. Retrospective and prospective clinical research studies, including bleeding history and laboratory markers for diagnosis as well as the use of DDAVP and VWF concentrates to manage or prevent bleeds in patients with VWD have been essential to provide general guidelines for VWD management. The large number of publications quoting VWD and VWF emphasizes the important role of VWF in medicine. [source] Management of acquired von Willebrand's sryndrome in a patient requiring major surgeryHAEMOPHILIA, Issue 6 2005J. M. Maddox Summary., We present the case of a patient with acquired von Willebrand's syndrome and a monoclonal gammopathy of undetermined significance who required cystectomy for relapsed transitional cell carcinoma (TCC) of the bladder. We demonstrated that infused von Willebrand factor (VWF) containing factor VIII concentrates had an unacceptably short half-life, but that this was significantly prolonged following combined therapy with plasma exchange and intravenous immunoglobulin (IVIgG). This approach was successfully utilized peri-operatively, with the total surgical blood loss less than would be expected even for a haemostatically normal patient. Trough VWF antigen and Ristocetin co-factor activity levels fell on the second postoperative day and we therefore administered further IVIgG. Levels again fell on the fifth postoperative day with the development of a Staphylococcus aureus septicaemia. At this point bleeding occurred from a surgical drain site requiring ,factor VIII inhibitor bypass activity' to secure haemostasis while further plasma exchange and IVIgG were administered. Now 5 years later, there is no evidence of recurrence of the TCC or progression of the monoclonal gammopathy. [source] The role of the platelet function analyser (PFA-100TM) in the characterization of patients with von Willebrand's disease and its relationships with von Willebrand factor and the ABO blood groupHAEMOPHILIA, Issue 3 2003I. C. Nitu-Whalley Summary. Determination of the closure time (CT) with the platelet function analyser (PFA-100TM) is a useful screening test for von Willebrand's disease (VWD) but its role in the characterization of VWD is not well established. We studied the relationship between the prolongation of the CT with adenosine diphosphate (ADP) (CT-ADP) and epinephrine (CT-EPI) cartridges and the von Willebrand factor (VWF) in 53 patients with VWD. We found that a relatively small percentage of the prolongation of the CT-ADR and CT-ADP (16 and 29%, respectively) was determined by a reduction in VWF levels. The CT-ADP was significantly more prolonged in the presence of qualitative defects in VWF but could not discriminate between the VWD subtypes. The ABO blood group had no effect on the prolongation of the CT or the bleeding time. In conclusion, the PFA-100TM appears of little use in the characterization of severity and subtype of VWD. [source] Efficacy and safety of a factor VIII,von Willebrand factor concentrate 8Y: stability, bacteriological safety, pharmacokinetic analysis and clinical experienceHAEMOPHILIA, Issue 5 2002A. Lubetsky Summary., The present study was undertaken to evaluate stability, pharmacokinetic profile and efficacy of continuous infusion of 8Y in patients with different types of von Willebrand disease (vWD). Following reconstitution, 8Y levels of von Willebrand factor ristocetin cofactor (vWF:Rco), vWF antigen and factor VIII coagulant activity (FVIII:C) decreased to about 80% of the baseline levels; addition of low molecular weight heparin decreased the level of FVIII:C even further. Reconstituted 8Y was found to be sterile for up to 6 days postreconstitution. Ten vWD patients (four with type 2A, three with type 3, two with type 1 and one with 2N) underwent pharmacokinetic analysis. The recovery of vWF: RCo was significantly lower in patients with type 3 vWD (1.4 ± 0.05% U,1 kg,1) compared withthat of the patients with types 1 (2.3 ± 0.52% U,1 kg,1) or 2A (2.0 ± 0.06% U,1 kg,1) vWD (P = 0.015). Type 3 vWD patients exhibited significantly higher vWF:RCo clearance (5.1 ± 1.1 mL kg,1 h,1) compared with that of patients with type 2A (2.8 ± 0.7 mL kg,1 h,1) and type 1 (2.6 ± 1.0 mL kg,1 h,1) vWD (P = 0.028). Accordingly, terminal half-life was lower in patients with type 3 vWD (8.0 ± 0.6 h,1) compared with type 2A (12.7 ± 5.9 h,1) or type 1 (14 ± 1.2 h,1) vWD patients. Multimeric pattern of vWF from patients' plasma was similar to that of 8Y. In two patients treated with 8Y by continuous infusion for prevention or treatment of bleeding haemostasis was achieved. Thus, 8Y is suitable and haemostatically effective for continuous infusion treatment in patients with vWD. [source] Use of ristocetin cofactor activity in the management of von Willebrand diseaseHAEMOPHILIA, Issue 2001B.M. Ewenstein von Willebrand disease (vWD), the most common of the hereditary bleeding disorders, arises from quantitative or qualitative defects in von Willebrand factor (vWF). vWF is a multimeric plasma protein that plays a key role in primary and secondary haemostasis. In the current classification scheme, vWD is divided into six subtypes that are based on the nature of the vWF defect. Therapeutic strategies depend on the accurate identification of these subtypes. In most clinical situations, desmopressin is effective treatment for the great majority of patients with mild (type 1) disease, while replacement therapy with factor VIII/vWF concentrates that contain high levels of vWF activity is required for most type 2 and nearly all type 3 vWD patients. Several factor VIII/vWF replacement products are available, one of which (Humate P) has been approved for the treatment of vWD by the US Food and Drug Administration. Preliminary results of recent studies support the hypothesis that treatment with factor VIII/vWF concentrates based upon the content of vWF activity as reflected in the ristocetin cofactor assay is practicable, safe and efficacious. The establishment of optimal treatment regimens with respect to dose intensity and duration will require further study. [source] Effect kinetics of desmopressin-induced platelet retention in healthy volunteers treated with aspirin or placeboHAEMOPHILIA, Issue 1 2000Lethagen Desmopressin is often used for haemostatic treatment in platelet dysfunction, but the effect kinetics of platelet responses and the mechanism of action are poorly known. This study aimed to determine the kinetics of platelet function responses induced by desmopressin in healthy volunteers treated with aspirin or placebo. Another aim was to correlate platelet responses to changes of von Willebrand factor (vWF) in plasma. We measured platelet function with a glass bead retention test, Ivy bleeding time, vWF:Ag and multimeric structure in plasma. Median baseline platelet retention was 12% (normal reference range 16,27%) during aspirin treatment and 18% during placebo. Median peak platelet retention after desmopressin was 33% during aspirin treatment and 34% during placebo. After about 3 h platelet function had returned to baseline. A second desmopressin dose after 3 h stimulated platelet retention to a similar extent as the first dose. There was no correlation between platelet responses and quantitative or qualitative changes of vWF in plasma. Platelet count did not change significantly. Thus, desmopressin's effect on platelet function lasts for about 3 h, but may be prolonged by a second dose immediately thereafter. These findings may have important clinical implications for patients with aspirin-induced platelet dysfunction undergoing surgery. [source] Enhanced expression of B7-1, B7-2, and intercellular adhesion molecule 1 in sinusoidal endothelial cells by warm ischemia/reperfusion injury in rat liverHEPATOLOGY, Issue 4 2001Naosuke Kojima To elucidate a role of costimulatory molecule and cell adhesion molecule in hepatic ischemia/reperfusion injury, we examined an alteration in B7-1 (CD80), B7-2 (CD86), and intercellular adhesion molecule 1 (ICAM-1; CD54) expression in the rat liver after warm ischemia/reperfusion injury. To induce hepatic warm ischemia in a rat model, both portal vein and hepatic artery entering the left-lateral and median lobes were occluded by clamping for 30 minutes or 60 minutes, and then reperfused for 24 hours. B7-1, B7-2, and ICAM-1 expressions in the liver were analyzed by immunofluorescence staining and real-time reverse transcription polymerase chain reaction (RT-PCR). Although B7-1 and B7-2 expressions were at very low levels in the liver tissues from normal or sham-operated control rats, both B7-1 and B7-2 expressions were enhanced at protein and messenger RNA (mRNA) levels in the affected, left lobes after warm ischemia/reperfusion. ICAM-1 protein and mRNA were constitutively expressed in the liver of normal and sham-operated control rats, and further up-regulated after warm ischemia/reperfusion. Localization of increased B7-1, B7-2, and ICAM-1 proteins, as well as von Willebrand factor as a marker protein for endothelial cells, was confined by immunofluorescence staining to sinusoidal endothelial cells in hepatic lobules. Data from quantitative real-time RT-PCR analysis revealed that B7-1 and B7-2 mRNA levels were elevated in hepatic lobes after warm ischemia/reperfusion (5.13- and 52.9-fold increase, respectively), whereas ICAM-1 mRNA expression was rather constitutive but further enhanced by warm ischemia/reperfusion (4.24-fold increase). These results suggest that hepatic sinusoidal endothelial cells play a pivotal role as antigen-presenting cells by expressing B7-1 and B7-2 in warm hepatic ischemia/reperfusion injury, and that B7-1 and/or B7-2 might be the primary target to prevent early rejection and inflammatory reactions after hepatic ischemia/reperfusion injury associated with liver transplantation. [source] | ||||||||||||||||||||||||||||||||||