vWF-Ag Levels Research Articles

The Significance of von Willebrand Factor Antigen Levels in Predicting the Severity of Coronary Artery Disease in Patients with ST-Segment Elevation Myocardial Infarction

Background When the endothelium of the coronary artery is damaged, it exposes the underlying structure to a series of events that can cause complete blockage and a myocardial infarction with ST-segment elevation (STEMI). One of the key factors in this process is a protein called von Willebrand factor (vWF) that helps platelets adhere to the damaged area. Our objective was to investigate the importance of measuring vWF levels in patients with STEMI to determine the severity of their coronary artery disease (CAD) on angiography. Methods The study included 30 patients who experienced their first STEMI. Patients with a history of CAD, cardiomyopathies, valvular heart disease, atrial fibrillation, anticoagulants, coagulation disorders, and pregnancy were not included in the study. After informed consent, all patients were subjected to routine blood investigations, electrocardiography, echocardiography, and coronary angiography. Blood samples were collected for vWF Ag within 24 hours of the patients’ arrival at the hospital. After the angiography, the coronary arteries were evaluated for stenosis and quantified using the modified Gensini score (mGS). The score was then correlated with vWF Ag levels using the Spearman rank correlation. Additionally, the receiver operating characteristic (ROC) curve was plotted for the value of vWF Ag levels to detect significant CAD. Results The average age of the group was (49.77 ± 10.79) years. The average levels of vWF Ag were (204.17% ± 51.99%). Patients with an mGS score of over 150 had higher levels of vWF Ag than those with a score of under 100 ( P < .001). There was a positive correlation ( r2: 0.67) between the parameters. On the ROC curve, vWF Ag levels higher than 186% predicted the presence of CAD, with an area under curve indicating sensitivity and specificity. Conclusion: In patients with STEMI, higher levels of vWF Ag were found to be associated with a greater severity of CAD.

Imbalance of the von Willebrand Factor — ADAMTS-13 axis in patients with retinal vasculopathy with cerebral leukoencephalopathy and systemic manifestations (RVCL-S)

BackgroundRetinal vasculopathy with cerebral leukoencephalopathy and systemic manifestations (RVCL-S) is an ultra-rare, autosomal-dominant small vessel disease caused by loss-of-function variants in the gene TREX1. Recently, elevated serum levels of von Willebrand Factor Antigen (vWF-Ag) pointed to an underlying endotheliopathy, and microvascular ischemia was suggested to contribute to the neurodegeneration in RVCL-S. Aim of this study was to further elucidate the endotheliopathy in RVCL-S.MethodsvWF-Ag and ADAMTS-13 activity were repeatedly measured in two patients with genetically confirmed RVCL-S. Renal biopsy of both RVCL-S patients and autoptic brain, renal, hepatic, and pulmonary specimen of one patient with RVCL-S were examined immunohistochemically in comparison to matched controls. In addition, cerebral methylome analysis was performed in the autoptic brain specimen calculating differentially methylated positions compared to controls.ResultsWhile vWF-Ag and activity was strongly elevated, ADAMTS-13 activity was low in RVCL-S and further decreased over the course of the disease. Autoptic brain specimen showed signs of thromboinflammation in cerebral small vessels, and vWF-Ag staining was strongly positive in cerebral and renal small vessels in RVCL-S, while only a light to moderate vWF-Ag staining was found in controls. Cerebral methylome analysis yielded 115 differentially methylated CpGs (p < 0.05) in the deceased RVCL-S patient compared to the eight controls without brain pathology. One of the hypomethylated genes coded for ADAMTS-13 (p = 0.00056).ConclusionsThese findings point to an imbalance of the vWF – ADAMTS-13 axis in patients with RVCL-S, that may finally lead to an accumulation of vWF-Ag in renal and cerebral small vessels. Elevated vWF-Ag levels may serve as an early serum marker reflecting disease activity. If confirmed, therapeutic approaches might aim at an inhibition of vWF-Ag or increase of ADAMTS-13 activity in the future.

Von Willebrand Factor Antigen Improves Risk Stratification for Patients with a Diagnosis of Resectable Hepatocellular Carcinoma.

Posthepatectomy liver failure (PHLF), complications of portal hypertension, and disease recurrence determine the outcome for hepatocellular carcinoma (HCC) patients undergoing liver resection. This study aimed to evaluate the von Willebrand factor antigen (vWF-Ag) as a non-invasive test for clinically significant portal hypertension (CSPH) and a predictive biomarker for time to recurrence (TTR) and overall survival (OS). The study recruited 72 HCC patients with detailed preoperative workup from a prospective trial (NCT02118545) and followed for complications, TTR, and OS. Additionally, 163 compensated patients with resectable HCC were recruited to evaluate vWF-Ag cutoffs for ruling out or ruling in CSPH. Finally, vWF-Ag cutoffs were prospectively evaluated in an external validation cohort of 34 HCC patients undergoing liver resection. In receiver operating characteristic (ROC) analyses, vWF-Ag (area under the curve [AUC], 0.828) was similarly predictive of PHLF as indocyanine green clearance (disappearance rate: AUC, 0.880; retention rate: AUC, 0.894), whereas computation of future liver remnant was inferior (AUC, 0.756). Cox-regression showed an association of vWF-Ag with TTR (per 10%: hazard ratio [HR], 1.056; 95% confidence interval [CI] 1.017-1.097) and OS (per 10%: HR, 1.067; 95% CI 1.022-1.113). In the analyses, VWF-Ag yielded an AUC of 0.824 for diagnosing CSPH, with a vWF-Ag of 182% or lower ruling out and higher than 291% ruling in CSPH. Therefore, a highest-risk group (> 291%, 9.7% of patients) with a 57.1% incidence of PHLF was identified, whereas no patient with a vWF-Ag of 182% or lower (52.7%) experienced PHLF. The predictive value of vWF-Ag for PHLF and OS was externally validated. For patients with resectable HCC, VWF-Ag allows for simplified preoperative risk stratification. Patients with vWF-Ag levels higher than 291% might be considered for alternative treatments, whereas vWF-Ag levels of 182% or lower identify patients best suited for surgery.

Increased Complement Activation and Decreased ADAMTS13 Activity Are Associated with Genetic Susceptibility in Patients with Preeclampsia/HELLP Syndrome Compared to Healthy Pregnancies: An Observational Case-Controlled Study.

Preeclampsia is a progressive multi-systemic disorder characterized by proteinuria, critical organ damage, and new-onset hypertension. It can be further complicated by HELLP syndrome (hemolysis, elevated liver enzymes, low platelets), resulting in critical liver or renal damage, disseminated coagulation, and grand mal seizures. This study aimed to examine the involvement of ADAMTS13, von Willebrand, and the complement system in the pathogenesis of preeclampsia/HELLP syndrome. We studied 30 Caucasian preeclamptic pregnant women and a control group of 15 healthy pregnancies. Genetic sequencing of ADAMTS13 and complement regulatory genes (MiniSeq System, Illumina) was performed. The modified Ham test was used to check for complement activation, ADAMTS13 activity, von Willebrand antigen (vWFAg) levels, and soluble C5b-9 levels were measured. Patients with preeclampsia had a decreased ADAMTS13 activity and increased C5b-9 levels. The vWFAg was significantly correlated with ADAMTS13 activity (r = 0.497, p = 0.003). Risk-factor variants were found in the genes of ADAMTS13, C3, thrombomodulin, CFB, CFH, MBL2, and, finally, MASP2. A portion of pregnant women with preeclampsia showed a decline in ADAMTS13 activity, correlated with vWFAg levels. These patients also exhibited an elevated complement activation and high-risk genetic variants in regulatory genes. Further research is needed to determine if these factors can serve as reliable biomarkers.

Von Willebrand factor levels in healthy blood donors and their association with blood group: A tertiary care hospital-based study.

von Willebrand disease is a common inherited bleeding disorder caused by the deficiency of von Willebrand factor (vWF).[1] The levels of vWF depend on several factors, including exercise, hormones, and ABO blood type.[2] This study was planned to evaluate plasma vWF levels and factor VIII (fVIII) levels in healthy blood donors and its association with the ABO blood group. The aim of this study was to evaluate plasma vWF levels and fVIII levels in healthy donors and its association with the ABO blood group. This study was done in 2016 healthy adult blood donors. Complete history and relevant examination were done along with ABO and Rh (D) blood group typing, complete blood count, prothrombin time, activated partial thromboplastin time, vWF antigen (Ag) level, fVIII coagulant assay, and other tests for hemostasis. Data were expressed in proportions and mean, median, and standard deviation, respectively. An appropriate test of significance was applied. P < 0.05 was considered statistically significant. vWF level of donors ranged from 24 to 186 IU/dL with a mean of 96.31 IU/dL. Low vWF Ag level (below 50 IU/dl) was found in 2.5% of donors while 0.1% (2/2016) had level <30 IU/dL. O Rh (D)-positive blood group donors had the lowest vWF level (87.85 IU/dL), while ARh (D)-negative donors had the highest vWF level (117.27 IU/dL). fVIII level of the donor population ranged from 22% to 174%, with a mean of 98.82%. About 2.48% of donors had fVIII levels below 50%. There was a statistically significant correlation between fVIII level and vWF level (P < 0.001).

Hemostatic and thrombotic parameters in acure leukemia- A comparison of pre and post remission induction phase

This study was aimed to compare hemostatic, fibrinolytic and thrombotic parameters in pre and post induction chemotherapy in acute myeloid leukemia (AML) and acute lymphoid leukemia (ALL). A total of 110 diagnosed acute leukemia patients and 40 normal individuals were enrolled in the study. Questionnaire were filled and patients’ blood specimens were collected before the commencement and post induction chemotherapy. Prothrombin time (PT), activated partial thromboplastin time (aPTT), von Willebrand factor antigen (vWF Ag), fibrinogen level, factor VIIIc (FVIIIc), D-Dimers, fibrinogen degradation products (FDPs), anti-thrombin III (AT), lupus anticoagulant (LA), protein C (PC), protein S and diluted russel viper venom test (DRVVT) were conducted in all the participants. A significant rise was identified in post-induction levels of PT, aPTT, vWF Ag, fibrinogen and factor VIII in acute leukemia patients. Analysis of fibrinolytic markers indicated increased D-Dimers and plasminogen levels while the levels of alpha 2 anti-plasmin were reduced in pretreated patients. Thrombotic markers’ assessment showed increased levels of AT and LA while decreased level of PC in pretreated acute leukemia patients. It was concluded that remission induction chemotherapy, in acute leukemia patients, significantly affects the coagulation, fibrinolytic and thrombotic parameters.

Clinical Spectrum and Laboratory Study of Von Willebrand Disease -Experience from Tertiary Care Hospital in Pakistan

Objective: To determine the clinical features and laboratory parameters of patients of von Willebrand disease (vWD) in our population.&#x0D; Study Design: Cross-sectional study.&#x0D; Place and Duration of Study: Department of Hematology, Armed Forces Institute of Pathology (AFIP), Rawalpindi Pakistan, from Jan to Jul 2019.&#x0D; Methodology: All patients newly diagnosed von Willebrand disease patients were assessed clinically. Complete blood counts, bleeding time, coagulation profile, von Willebrand antigen levels and FVIII levels were determined.&#x0D; Results: A total of 66diagnosed patients of von Willebrand disease were included in the study. Out of these 15 (22.7%) were male while 51 (77.2%) were females. The most common clinical symptom was pallor, seen in 49 (74.2%) patients, followed by epistaxis in 36 (54.5%) and gum bleeding in 28 (42.4%) patients. Consanguineous marriages were found in 40 cases (60.6%) and family history was positive in 23 (34.8%). Patients mean vWF Ag level was4.29 ± 7.7 IU/dL while mean FVIII levels was 5.18 ± 7.8 1 U/mL.&#x0D; Conclusion: Von Willebr and disease is among the most common inherited bleeding disorder which presents with a classical pattern of mucocutaneous/soft tissue bleed, with pallor epistaxis and gum bleed being the most common presenting complaints.

The Role of von Willebrand Factor Antigen in Predicting Survival of Patients with HBV-Related Cirrhosis

Objective The model for end-stage liver disease (MELD) scoring system cannot be used to assess the deterioration of patients with liver cirrhosis caused by infection and portal hypertension. Elevated von Willebrand factor antigen (vWF-Ag) in plasma is associated with portal pressure and complications in patients with liver cirrhosis. We aimed to evaluate whether the addition of vWF-Ag can improve the risk prediction ability of the MELD scoring system. Methods A total of 228 patients with hepatitis B virus (HBV)-related liver cirrhosis were eligible for inclusion in this retrospective study. The vWF-Ag level was assessed by enzyme-linked immunosorbent assay (ELISA). The endpoint of this study was defined as the time to liver transplantation or death. Univariate and multivariate analyses were performed to assess the risk factors associated with transplant-free mortality. Receiver operating characteristic (ROC) curve analysis was used to assess potential discriminatory variables for transplant-free mortality. Results During a median follow-up interval of 30.23 months, 124 patients (54.4%) reached the endpoint of this study. Patients who died or underwent liver transplantation had elevated levels of MELD and vWF-Ag. Moreover, vWF-Ag and MELD showed comparable predictive potential for transplant-free survival (area under the curve [AUC], vWF-Ag = 0.71; AUC, MELD = 0.73). Ultimately, vWF-Ag can significantly improve the predictive potential of MELD in determining transplant-free mortality (AUC, MELD-vWF-Ag = 0.79, P = 0.006). Conclusion An elevated vWF-Ag level was independently associated with transplant-free mortality in patients with liver cirrhosis. The inclusion of vWF-Ag in the MELD scoring system can improve mortality predictions in patients with liver cirrhosis.

The Level of vWF Antigen and Coagulation Markers in Hospitalized Patients with Covid-19.

BackgroundThe coagulopathy of COVID-19 still awaits more clarification, and one approach that has not been investigated is to compare the hemostatic changes between COVID-19 and non-COVID-19 infected patients.ObjectiveThis study aims to study COVID-19 coagulopathy by measuring markers of endothelial injury and coagulation, including anticoagulants (TFPI, protein C, protein S, and AT) in COVID-19 patients and compare them with non-COVID-19 patients early in the course of the disease.MethodologyThis is an observational, prospective cross-sectional study comparing the levels of protein C, protein S, antithrombin (AT) III, clotting factor (F) VIII, von Willebrand factor (vWF) and coagulation screening tests (PT and a PTT), fibrinogen, D-dimer in COVID-19 patients admitted during the same time with non-COVID-19 infections. The demographic and clinical data of the patients were collected from electronic medical records during admission. Blood tests were extracted within 24 hours of admission for both groups.ResultsFifty-four (66.7% males) consecutive COVID-19 patients and 24 (59% males) non-COVID-19 controls were enrolled in the study from October 2020 till December 2020. COVID-19 patients were significantly older than non-COVID-19 (57.7±14.2 vs 50±19.8 years, p=0.005). Fibrinogen level was significantly higher in COVID-19 patients compared to controls (5.9±1.48 vs 3.9±1.57, p<0.001). There was no statistically significant difference in the level of FVIII, protein C, S, ATIII, and D-dimer between the two groups. The level of vWF Ag was statistically higher in COVID-19 patients (276.7±91.1 vs 184.7±89.4, p=0.0001). There was significant thrombocytopenia and lymphopenia among COVID-19 patients. Inflammatory markers, CRP, ferritin, and LDH, were increased in COVID-19 patients compared to non-COVID-19, but the difference was not statistically significant. High fibrinogen and vWF AG levels were the two independent variables found in COVID-19 patients.ConclusionThe level of vWF Ag is increased early in the course of COVID-19 infection. This can be used as a biomarker for endothelial injury, which is peculiar to COVID-19 infection.

Evaluation of von Willebrand factor as a marker for early diagnosis of Acute Respiratory Distress Syndrome in comparison to Interleukin-6

BackgroundAcute respiratory distress syndrome (ARDS) constitutes a clinical phenotype of severe lung injury associated with many causes. Endothelial activation and injury is a component of ARDS. The release of von Willebrand factor (vWF) indicates direct endothelial cell damage has occurred, and this can be used as a marker of endothelium injury. The aim of the study was to investigate the diagnostic value of vWF antigen as a determinant of early detection of ARDS in comparison to interleukin-6 (IL-6) as a control biomarker. vWF antigen and IL-6 were measured in 60 patients who were at risk of developing ARDS on T0 (at the start of the study), T48 (after 48 h), and T72 (after 72 h).ResultsHigher vWF Ag levels were seen in patients at risk of developing ARDS with direct cause of lung injury than those with indirect causes. Include groups I and II. There was a highly significant increase between the “at risk of developing ARDS” patients, VWF Ag, and IL-6 levels. The results were recorded at T0 (i.e., at start of the study baseline reading), T48 (after 48 h), and T72 (after 72 h), p 0.001 and p 0.05, respectively. A value of vWF Ag of 447% on the 3rd day of ARDS showed a sensitivity of 94.9% and specificity 56.7% compared to IL-6 at 246 pg/ml with 79.5% sensitivity and 52.4% specificity. As a comparison between VWF and IL6 levels among ARDS patients, they both show statistical correlation together.ConclusionThe results of our study point out to VWF as a sensitive and good diagnostic marker for ARDS diagnosis.

Extending the post-thaw viability of cryoprecipitate.

Cryoprecipitate has a short post-thaw expiry time of 6 h. The aim of this study was to assess the stability and function of cryoprecipitate components (FVIII, fibrinogen, vWF, and FXIII) and cryoprecipitate sterility up to 120 h post-thawing when stored at two temperatures (2-6°C and room temperature [20-24°C]). Twenty batches (110 individual units) of time-expired, thawed cryoprecipitate were collected. Units were sampled at the 6-h expiration mark and then stored at 2-6°C or room temperature (RT). They were resampled every 24 h for 120 h. One unit from each batch was sent for sterility testing at 120 h. Samples had FVIII (one stage and chromogenic), fibrinogen, FXIII, vWFag, and vWF:RCo assays performed in batches. Rotational thromboelastometry (ROTEM) was also performed. FVIII levels declined significantly at 120 h post-thawing at both RT and 2-6°C, but still met international standards for FVIII content. Fibrinogen, vWF antigen, and FXIII levels reduced minimally over 120 h and always met international standard requirements when stored at either temperature. ROTEM analysis demonstrated that fibrinogen function was not compromised at 120 h post-thawing under both storage conditions. vWF:RCo levels declined significantly over 120 h at both storage temperatures. No bacterial contamination was detected in 20 units of cryoprecipitate following storage for 120 h post-thawing. These results demonstrate that extension of the storage time of thawed cryoprecipitate to 120 h, stored at either 2-6°C or RT, is feasible while still maintaining required FVIII, fibrinogen, and vWFag levels. Storage at 2-6°C has the advantage of reduced risk of potential bacterial contamination.

Endothelial Activation and Immune Thrombocytopenia: An Engagement Waiting for Consolidation.

Immune thrombocytopenia (ITP) appears to be a heterogeneous disease. In some patients, autoimmunity may be associated with an inflammatory process, and in other patients, low platelets may interfere with other aspects of the coagulation system. Either may predispose to thrombosis or bleeding. Further investigation of the interactions of platelets, with inflammatory cytokines and endothelial biomarkers, may help us to better understand the disease, and to recognize those patients at risk of bleeding, or conversely thrombosis. The aim of this work is to estimate von Willebrand factor (vWF) and vascular cellular adhesion molecule (V-CAM) serum levels in adult immune thrombocytopenic patients (ITP) and to decipher their possible clinical correlates. Eighty adults (≥ 18 years) were enrolled in the study; naive newly diagnosed 40 patients with primary ITP (according to the ASH 2019) and 40 sex and age-matched healthy controls, all groups are subjected for complete blood count (CBC), liver, and renal function tests, ESR, CRP, V-CAM, and VWF-Ag by enzyme-linked immunosorbent assay (ELISA). There was a highly statistically significant difference between case and control as regards to the mean level of VWF-Ag and V-CAM. vWF and V-CAM could serve as biomarkers for endothelial alterations and should be investigated as a predictor of thrombocytopenic bleeding and tailor patient management accordingly.

The association of PAI-1 with 24 h blood pressure in young healthy adults is influenced by smoking and alcohol use: The African-PREDICT study

Background and aimsThe association between plasminogen activator inhibitor-1 (PAI-1) and blood pressure is well established, but it is debatable whether raised PAI-1 levels precede or result from raised blood pressure. Furthermore, it is unclear whether this association already exists in the absence of overt hypertension and to what degree it is influenced by health behaviours. Our aim was to investigate the association of 24 h blood pressure with PAI-1 activity (PAI-1act) in a young, healthy cohort, and to assess the influence of alcohol consumption and smoking on these associations. Methods and resultsHealthy black and white men and women (aged 20–30 years, n = 1156) were cross-sectionally analysed. Statistical analysis was performed first split by ethnicity and sex and then by alcohol consumption and smoking. Regression analyses adjusted for age revealed positive associations of 24 h blood pressure with PAI-1act in most groups (p < 0.05). In multivariate-adjusted analyses, significance was lost in all groups except black men, who also had higher monocyte chemoattractant protein-1 (MCP-1) and von Willebrand factor antigen (vWFag) compared to white men (both p < 0.001). Analyses in black men, split by self-reported alcohol use and smoking, revealed 24 h blood pressure-PAI-1act associations only in alcohol users (24 h SBP [B = 4.22, p < 0.001], DBP [B = 2.04, p = 0.015] and PP [B = 2.18, p = 0.013]) and smokers (24 h SBP [B = 6.10, p < 0.001] and PP [B = 4.33, p = 0.001]). ConclusionOur findings support a positive association between 24 h blood pressure and PAI-1, particularly in individuals with higher MCP-1 and vWFag levels. Furthermore, smoking and alcohol consumption play an important role in modifying the association between blood pressure and PAI-1.

The von Willebrand Factor Facilitates Model for End-Stage Liver Disease-Independent Risk Stratification on the Waiting List for Liver Transplantation.

Background and AimsThe Model for End‐Stage Liver Disease (MELD) is used for clinical decision‐making and organ allocation for orthotopic liver transplantation (OLT) and was previously upgraded through inclusion of serum sodium (Na) concentrations (MELD‐Na). However, MELD‐Na may underestimate complications arising from portal hypertension or infection. The von Willebrand factor (vWF) antigen (vWF‐Ag) correlates with portal pressure and seems capable of predicting complications in patients with cirrhosis. Accordingly, this study aimed to evaluate vWF‐Ag as an adjunct surrogate marker for risk stratification on the waiting list for OLT.Approach and ResultsHence, WF‐Ag at time of listing was assessed in patients listed for OLT. Clinical characteristics, MELD‐Na, and mortality on the waiting list were recorded. Prediction of 3‐month waiting‐list survival was assessed by receiver operating characteristics and net reclassification improvement. Interestingly, patients dying within 3 months on the waiting list displayed elevated levels of vWF‐Ag (P < 0.001). MELD‐Na and vWF‐Ag were comparable and independent in their predictive potential for 3‐month mortality on the waiting list (area under the curve [AUC], vWF‐Ag = 0.739; MELD‐Na = 0.764). Importantly, a vWF‐Ag cutoff at 413% identified patients at risk for death within 3 months of listing with a higher odds ratio (OR) than the previously published cutoff at a MELD‐Na of 20 points (vWF‐Ag, OR = 10.873, 95% confidence interval [CI], 3.160, 36.084; MELD‐Na, OR = 7.594, 95% CI, 2.578, 22.372; P < 0.001, respectively). Ultimately, inclusion of vWF‐Ag into the MELD‐Na equation significantly improved prediction of 3‐month waiting‐list mortality (AUC, MELD‐Na–vWF = 0.804).ConclusionsA single measurement of vWF‐Ag at listing for OLT predicts early mortality. Combining vWF‐Ag levels with MELD‐Na improves risk stratification and may help to prioritize organ allocation to decrease waiting‐list mortality.

Evaluation of endothelial microparticles as a prognostic marker in hemolytic disease of the newborn in China.

ObjectiveThis study aimed to evaluate endothelial microparticles (EMPs) as a potential prognostic marker in hemolytic disease of the Chinese neonate.MethodsWe compared 29 newborns with ABO hemolytic disease of the newborn (ABO HDN), 22 newborns with Rh HDN, and 21 healthy newborns with matched mother and infant blood groups (controls). Markers of hemolysis and von Willebrand factor antigen (vWF Ag) were analyzed. EMP (CD144+) levels were measured before and after therapy.ResultsvWF Ag and pretherapy EMP levels were higher in the ABO HDN and Rh HDN groups than in the control group. Additionally, vWF Ag and pretherapy EMP levels were significantly higher in the ABO HDN group than in the Rh HDN group. Posttherapy EMP levels were decreased compared with pretherapy levels in the ABO HDN and Rh HDN groups. Moreover, hemoglobin and indirect bilirubin levels were independently correlated with pretherapy EMP levels in the ABO HDN group.ConclusionOur findings indicate that EMP measurement in neonates with HDN may provide a novel method of monitoring possible severe vascular dysfunction in patients in China. An external validation in larger datasets is necessary for further study.

Thrombotic thrombocytopenic purpura in a 13 year boy – a case report

Thrombotic thrombocytopaenic purpura (TTP) is a very rare presentation in the paediatric population.1 We report a previously healthy 13-year-old boy of Korean heritage, who presented to the Children’s Hospital Westmead with prolonged epistaxis, thrombocytopenia (platelet count of 5×109/L) and haemoglobinuria. There were no neurological or renal manifestations present. There was no significant haematological family history. On examination he had widespread petechiae and ecchymosis, dark coloured urine and skin pallor. He was anaemic and the blood film demonstrated red cell fragmentation consistent with microangiopathic haemolytic anaemia (MAHA). The coagulation studies were normal. He was treated with plasmapheresis, and subsequently commenced on rituximab and prednisolone therapy. He suffered recurrent allergic reactions to blood products requiring a tailored premedication regime. Overall he tolerated the treatment well. The prednisolone has been weaned over six months, on the basis of clinical and haematological improvement. On investigation, he had a deficiency of the vWF cleaving protease ADAMTS13 (2%) and high levels of vWF Ag (333%). Autoantibodies inhibiting the protease were detected suggesting an autoimmune cause of his TTP.1 Interestingly, 6 months later he was found to have a large goitre, with associated biochemical hypothyroidism and autoantibodies. This is under ongoing investigation.

Multicenter Pharmacokinetic Evaluation of rFVIII-Fc (Elocta) in a Real Life and Comparison with Non-Extended Half-Life FVIII Concentrates

Background: The use of extending half-life (EHL) FVIII or FIX products is today a current strategy in Hemophilia A (HA) patients for improving prophylaxis and reducing the number of IV injections. Fc fusion technology is based on the use of the neonatal Fc receptor and endogenous Fc recycling pathway, thereby prolonging the half-life (T1/2) of rFVIII-Fc. A single dose phase 1/2 pharmacokinetic (PK) study performed in 16 severe HA patients demonstrated a prolonged T ½ of rFVIII-Fc equal to 18.8 hours (mean) compared to 12.2 hours with one conventional rFVIII (Malhangu et al. Blood 2014).The aim of the present study was to analyze PK data collected with Elocta® in “real life” i.e. in a large cohort of patients treated in 13 different French hemophilia care centers, and results were compared to those obtained with conventional FVIII, when available. Importantly, this study was performed without any involvement of Sobi, the pharmaceutical company that provides Elocta® in France.Patients and methods: 113 severe Hemophilia A (HA) patients with the following characteristics were included: mean age 30 years (range 3 - 70); weight 65 Kg (17-125); total FVIII-Fc dose injected 2650 IU (500-5750); FVIII-Fc IU/Kg: 41 (25 - 59); VWF Ag 98% (41-279). The FVIII recovery (R) was calculated as follows: (body weight (Kg) x observed increased in FVIII (%))/administered dose (IU/Kg). The T1/2 was calculated with the following formula: Ln2/((Ln FVIII% T1 - Ln FVIII%T2)/T2 - T1)), with T1 ≥ 4 hours and T2 ≥ 24 hours.Results were compared to those performed with conventional FVIII (non EHL-FVIII) in 48 patients (Advate® n = 14, Refacto® n = 2, Helixate®/Kogenate®/Kovaltry® n = 29, Factane® n = 3)Results: rFVIII-Fc activity measured by one stage clotting assay (OSA) was 20% lower than those obtained with chromogenic assay (CSA) in samples with FVIII levels higher than 20%, but this difference was lower than 10% when FVIII levels < 20%. Therefore, rFVIII-Fc recovery (R) always appeared lower when measured with OSA (Mean 2.38, range 1.33 - 5.7) than with CSA (mean 2.82, ranges 1.35 - 5.5) (p < 0.0001). No correlation was found between this recovery and age, weight, injected doses or VWF Ag levels. Mean T1/2 measured with rFVIII-Fc equaled 15 hours whatever the measurement method used (OSA or CSA), and was strongly correlated with vWFAg levels (R2 = 0.57). Using OSA, significantly lower recovery (1.86 vs. 2.49, p = 0.0002) and T1/2 values (11.75 vs. 15.13 hours, p = 0.0004) were measured in children (< 10 years, n = 19) compared to adults. Similar differences were evidenced with data obtained by CSA (recovery : 2.26 vs. 2.93, p = 0.0009 and T1/2 : 11.4 vs. 15.6 h, p = 0.004, n = 14 children < 10 years).PK parameters of FVIII-Fc were compared to those obtained with non EHL-FVIII (rFVIII or pdFVIII) in 47 patients (mean T1/2 equal to 10.0 hours; range 5.3 - 21.2), and half-lives of these two categories of products were well correlated (r2 = 0.57). However, the apparent benefit provided by FVIII-Fc was variable from one patient to another, with a mean T1/2 rFVIII-Fc / T1/2 FVIII ratio ranging from 0.6 to 2.4 (mean 1.4). Interestingly, the increase in T1/2 with FVIII-Fc was lower than 20% only in patients previously treated with BHK-derived rFVIII i.e. Helixate®/Kogenate®/ Kowaltry® (n=10). Whatever the FVIII injected (FVIII-Fc or other non EHL-FVIII), the T1/2 measured was also strongly correlated to vWF levels, which were significantly lower in patients for whom the mean T1/2 rFVIII Fc / T1/2 FVIII ratio was > 1.3 (mean 79% vs 116% in the others, p=0.017).Conclusion: This study is the first to report PK data obtained with rFVIII-Fc (Elocta®) in a large group of HA patients. Our results confirm the benefit of rFVIII-Fc in most HA patients, adults or children, but also emphasize the impact of vWF on half-life of rFVIII-Fc or conventional non EHL-FVIII. Indeed, the benefit of rFVIII-Fc clearly appears higher in patients with lower vWF levels, with a more significant prolongation of T1/2. DisclosuresNo relevant conflicts of interest to declare.

Von Willebrand Factor Antigen Predicts Outcomes in Patients after Liver Resection of Hepatocellular Carcinoma.

Background/Aimsvon Willebrand factor antigen (vWF-Ag) is a noninvasive predictor of portal hypertension that serves as a negative prognostic marker in various malignancies. Increased portal hypertension is associated with higher postoperative morbidity and decreased survival after hepatectomy. The purpose of this study was to determine the correlation between vWF-Ag, postoperative morbidity and oncological outcome.MethodsThis analysis includes 55 patients who underwent liver resection for hepatocellular carcinoma (HCC) between 2008 and 2015 with available preoperative vWF-Ag levels. The primary endpoints were postoperative complications and long-term outcome, including overall and disease-free survival.ResultsThe median plasma level of vWF-Ag was 191% (range, 162.5% to 277%). There was a significant correlation between vWF-Ag levels and tumor size in the resected specimens (p=0.010, r=0.350). Patients who developed any grade of postoperative complication had significantly higher preoperative vWF-Ag levels (216% [range, 178% to 283.25%] vs 176% [range, 148% to 246%], p=0.041). Median overall survival was 39.8 months in patients with high vWF-Ag levels (≥191%) compared with 73.4 months in patients with low levels (<191%, p=0.007). Of note, there was a remarkable disparity in the number of patients who died of HCC with low versus high vWF-Ag levels (14.8% vs 28.6%, p=0.011).ConclusionsvWF-Ag may serve as a prognostic marker for the outcome of patients undergoing liver resection for HCC that is closely connected to tumor size, postoperative complication rate and long-term outcome.

VWF correlates with visceral and pericardial adipose tissue in patients with a recent stroke of suspected cardiogenic etiology.

AimsA chronically elevated level of von Willebrand factor (vWF) is a common finding in patients with cardiovascular diseases. Obesity is a well-recognized risk factor for thrombotic cardiovascular complications including ischemic stroke, and it has been linked with increased plasma vWF. We evaluated whether elevated plasma levels of vWF associate with areas of visceral (VAT), pericardial (PAT), and subcutaneous adipose tissue (SAT) compartments in patients with acute/subacute stroke.Methods and resultsA total of 69 patients with stroke of suspected cardiogenic etiology were examined. The plasma level of vWF antigen (vWF-ag) was measured both in the acute phase and in the chronic phase three months after stroke. The areas of VAT and/or PAT were assessed with computed tomography. As expected, in stroke patients, the levels of plasma vWF-ag were significantly higher than in the national reference population both in the acute and in the chronic phase. The level of vWF-ag in the chronic phase correlated with the amounts of VAT and PAT, but not with subcutaneous adipose tissue.ConclusionsThese results agree with previous observations of the chronic inflammation/prothrombotic tendency in patients with cerebrovascular disease. Future studies should seek to clarify the role of visceral type adipose tissue in the pathophysiology of ischemic stroke.

Possible Risk Factors of Thrombosis in Chinese Patients with Paroxysmal Nocturnal Hemoglobinuria

▪Background: Paroxysmal nocturnal hemoglobinuria (PNH) is a rare disease caused by an acquired mutation of the X-linked PIGA gene on the hematopoietic stem cell. Thrombosis is one of the most common causes of mortality in PNH, but the predisposing factors for thrombosis are yet to be defined. In this study, we outline the clinical characters of thrombotic PNH and detect the susceptible genes which may lead to thrombotic formation.Methods: There were totally 94 patients with PNH diagnosed between 2011 and 2015 enrolled in the study. Clinical data like sex, age, hemoglobin level, reticular cell percentage, white blood cell and platelet count, LDH level, CD59- and FLAER granulocytes percentage, thrombophilia risk factors like level of protein C, protein S, antithrombin III, APC resistance, blood fat, phospholipid antibody were evaluated. Samples from patients were genotyped for the reported 33 alleles in 21 genes including MTHFR, PROC, PROS, F2, F5, ABO, prothrombin and other genes which are reported as high risk factors for venous thromboembolism (VTE) by polymerase chain reaction fragment length polymorphism methods (PCR-RFLP). Furthermore, we detected plasma VIII factor and vWF levels which were affect by ABO polymorphism.Results:Of the 94 PNH patients, 16 (17%) patients had at least 1 episode of thrombotic event. Only 2 patients had arterial thrombosis and 14 patients had venous thrombosis. The medium age of patients with thrombosis was 42-year old, similar to those without (43-year-old, p=0.199). Male : female ratio was 1.29 in thrombosis group and 1.16 in non-thrombosis group (p=1.000). Although there was no difference in level of hemoglobin, white blood cell count, platelet count, reticular cell count, LDH, protein C, protein S, antithrombin III, APC resistance, blood fat, phospholipid antibody level (p>0.05) between patients with thrombosis and those without, the percentage of CD59- erythrocytes( p=0.001 ), CD59- granulocytes ( p=0.004 ) and FLAER- granulocytes (p=0.003) was higher in thrombotic patients. Patients with the TT genotype (rs495828 in the ABO gene) were approximately 3.03 folds prone to thrombus formation than those with the GG genotype (p=0.0204 ), and patients with the TC genotype (rs2519093 in the ABO gene) were approximately 4.24 folds prone to thrombus formation than those with the CC genotype ( p=0.0352 ). In addition, minor allele frequencies of rs495828 or rs2519093 and CD59- erythrocytes were independent risk factor for thrombosis in PNH patients. No association was detected between other SNPs and risk to thrombosis. There was no difference in level of vWF-Ag (156% vs 152%, p=0.870) and VIII factor (190% vs 156%, p=0.198) between patients with or without thrombosis, although the level was much higher in PNH patients than normal controls (178% vs 107%, p=0.005 and 203% vs 128%, p=0.003 respectively).Conclusion: Compared with non-thrombotic patients, thrombotic PNH patients have have bigger PNH clone. And for the first time, our results suggested that the rs495828/rs2519093 in the ABO gene confers risk to thrombosis in PNH. Therefore, rs495828/rs2519093 polymorphism may represent a potential genetic biomarker in PNH patients for thrombus formation. DisclosuresNo relevant conflicts of interest to declare.