BACKGROUND: Snake venom botrocetin facilitates von Willebrand factor (VWF) binding to platelet GPIbα and has been widely used for the diagnosis of von Willebrand diseases and GPIb-related disorders. Botrocetin is also commonly employed for the development/characterization of antithrombotics targeting the GPIb-VWF axis.
OBJECTIVE: To explore the alternative receptor(s)/mechanisms participate in botrocetin-induced platelet aggregation.
METHODS: The effects of botrocetin on platelet aggregation were examined using platelets from wild-type, VWF and fibrinogen-deficient, GPIbα-deficient, IL4Rα/GPIbα-transgenic and αIIbβ3-deficient mice, Bernard-Soulier syndrome (BSS) and healthy human samples. Platelet-fibrinogen and platelet-VWF interaction were measured using flow cytometry. GPIbα-VWF binding was evaluated utilizing ELISA. Botrocetin-αIIbβ3 and botrocetin-GPIbα interactions were measured using ELISA and fluorescence anisotropy assays. Heparinized whole blood from healthy donors was examined for thrombus formation and growth in a perfusion chamber.
RESULTS: Botrocetin could induce aggregation of platelets from a BSS patient and GPIbα-deficient mice as well as platelets lacking the N-terminal extracellular domain of GPIbα. Botrocetin could interact with αIIbβ3 and facilitated αIIbβ3-VWF interaction independent of GPIb. Botrocetin competitively bound to the ligand-binding domain of activated rather than resting αIIbβ3. Although botrocetin-induced platelet aggregation requires VWF, strikingly, in the absence of VWF, botrocetin blocked fibrinogen and other ligand binding to αIIbβ3, and inhibited platelet aggregation and thrombus formation. Consistently, recombinant botrocetin defective in VWF binding inhibited αIIbβ3 and GPIb-mediated platelet aggregation, spreading and thrombus formation.
CONCLUSIONS: Our study provides insights into avoiding the misdiagnosis of GPIb-related disorders and developing botrocetin mutants as potential new antithrombotics that may simultaneously target both αIIbβ3 and GPIbα.

OBJECTIVE: Using a rat model, we investigated the effect of multidisciplinary rehabilitation, including aerobic training and ointment, on the ROM, vWF, VEGF content, and femoral artery hemodynamics in rats with joint contracture.
METHODS: A total of 44 Wistar rats were divided into the normal control group (NC, eight rats) and the experimental group (EG). A joint contracture model was established for the rats in the EG group by an external fixator. After fixator removal, 32 rats are further divided into the MC, SC, RE, and SR groups (n = 8). Before and after the 42 day intervention, the ROM, vWF, VEGF, PS, ED, and RI were measured using X-ray imaging, ELISA, and color Doppler ultrasound, respectively.
RESULTS: After fixator removal, ROM for EG group was lower than that of the NC group (p < .01). After the intervention, ROM for the SR, RE, and SC groups was improved. The ROM for the SR group reached a similar value for NC group. vWF and VEGF levels in SR group were lower than in the MC, SC, and RE groups (p < .05), and had a similar value to the NC groups. PS value for SR and RE groups was higher than the MC and SC groups. The RI value for SR group was higher than that of NC and MC groups.
CONCLUSIONS: Multidisciplinary rehabilitation used in this study can treat joint contracture synergistically. It improves the ROM of the joint, reduces the content of vWF and VEGF, and improves the femoral artery hemodynamics.

A 28-year-old woman was found to have coagulation factor Ⅷ activity (FⅧ∶C) <1% and von Willebrand factor antigen (VWF∶Ag) <1% during routine prenatal examinations. No pathogenic variation was found in the exon region of the VWF gene using next-generation sequencing. The clinical presentation of this patient does not match the clinical characteristics of type Ⅲ hemophilia [von Willebrand disease (VWD) ]; therefore, third-generation sequencing technology was used to perform whole-genome sequencing on the patient and her family members. Multiple members of the patient\'s paternal family carried a heterozygous variant of VPS33B, c.869G>C. The family members carrying this variant all had varying degrees of reduced VWF levels (39% -56% ). Moreover, the proband was detected with the heterozygous variant c.1474dupA in GP1BA. The ACMG and Clinvar databases determined that this variation was associated with platelet-type pseudo VWD. The decrease in VWF levels caused by heterozygous variations in VPS33B in families is the first international report, and no previous studies have reported cases of severe decrease in plasma VWF levels caused by double heterozygous variations in VPS33B and GP1BA.
一例28岁女性，孕期常规体检发现凝血因子Ⅷ活性（FⅧ∶C）<1%、血管性血友病因子抗原（VWF∶Ag）<1%。二代测序未发现其VWF基因外显子区域存在致病变异。由于该患者临床表现与Ⅲ型血管性血友病（VWD）临床特征不符，因此采用三代测序技术对该患者及其家系成员进行全基因组测序，发现该患者父系家族中有多位成员中携带VPS33B基因杂合变异c.869G>C，携带该变异的家系成员均有不同程度的VWF水平降低（39%～56%）。同时，先证者还检出GP1BA基因杂合变异c.1474dupA，ACMG及Clinvar数据库判断该变异与\"血小板型假性VWD\"相关。VPS33B基因杂合变异导致的VWF水平降低家系为国际首次报道，VPS33B基因与GP1BA基因双重杂合变异引起血浆VWF水平严重降低病例之前也未见报道。.

Bleeding complications are frequently observed in patients undergoing extracorporeal membrane oxygenation and are associated with increased mortality. Due to the complex mechanisms, managing bleeding during ECMO remains a challenge. Acquired von Willebrand syndrome (AVWS) in ECMO highlights a potentially reduced affinity of von Willebrand factor (vWF) for binding to platelets and collagen in response to vascular damage, thus contributing to increased bleeding in ECMO patients. Conventional coagulation parameters are incomplete predictors for bleeding in ECMO patients, whereas AVWS is often overlooked due to the absence of vWF evaluation in the coagulation profile. Therefore, clinical physicians should evaluate AVWS in patients experiencing bleeding complications during ECMO support.

Thrombotic thrombocytopenic purpura (TTP) is a life-threatening, often immune-mediated disease that affects 2-13 persons per million per year. Hemolytic anemia, thrombocytopenia, and end-organ damage due to the formation of microthrombi are characteristic of TTP. ADAMTS13 is a disintegrin, metalloproteinase, cleaving protein of von Willebrand factor (VWF) that processes the VWF multimers to prevent them from interacting with platelets and, in turn, to microvascular thrombosis. Prompt diagnosis of TTP is critical yet challenging. Thrombotic microangiopathies have similar clinical presentation. Measurement of ADAMTS13 activity helps in the differential diagnosis. Less than 10% ADAMTS13 activity is indicative of TTP. Laboratory ADAMTS13 activity assays include incubating the test plasma with the substrate (full-length VWM multimers) and detection with direct or indirect measurement of the cleavage product. The purpose of this study is to examine the diagnostic potential, advantages, and weaknesses of the ADAMTS13 potency in TTP.

OBJECTIVE: SARS-CoV-2 (COVID) induces systemic thrombotic complications including acute ischemic stroke. In this case series, we report markers of inflammation, coagulation factors including von Willebrand factor antigen, and rotational thromboelastometry (ROTEM) data.
METHODS: Retrospective case series of COVID patients seen at a single comprehensive stroke center between 2020 - 2022. For patients undergoing mechanical thrombectomy (MT), ROTEM data was collected during the procedure and analyzed on ROTEM delta system.
RESULTS: Fifteen patients (33.3% female) median age 65-years-old presented with COVID and acute ischemic stroke. Thirteen had LVO. The mean NIHSS was 15 (range 0 - 35) on admission and 18 (0 - 42) at discharge. Most were cryptogenic (N=7, 46.7%), followed by cardioembolic (N=6, 40%) and large artery-to-artery embolization (N=2, 13.3%). mRS was < 3 in 8 (53%) patients at discharge. None of the patients were on anticoagulation, and five were on antiplatelet therapy pre-hospitalization. Seven received thrombolytics with alteplase (tPA), and 10 had MT. Baseline platelet count was 102 K/uL (range 102 - 291 K/uL). vWF was measured in 12 patients, all elevated, with seven having levels >400 (180%). ROTEM data was collected in six patients. Three who received tPA had abnormal EXTEM and FIBTEM data (CT extem > 85secs, A10 EXTEM < 45mm, and A10 FIBTEM < 10mm). Notably, INTEM (CT INTEM >208secs) was abnormal in five of the six patients, two of whom did not receive tPA.
CONCLUSIONS: Elevated vWF antigen levels with abnormal ROTEM data suggests that COVID induces changes in the clotting cascade. More robust research is needed to investigate these findings. Thrombolytics, MT, and antiplatelet agents should be utilized to treat COVID-related ischemic stroke based on current clinical guidelines.

Our aim was to explore possible relationships between serum levels of biomarkers in patients with hand-arm vibration injury in relation to the severity of the vascular, i.e., Raynaud\'s phenomenon (RP), and neurosensory manifestations, the current exposure level, and the duration of exposure. This study was of case series design and involved 92 patients diagnosed with hand-arm vibration injury. Jonckheere\'s trend test was used to assess any association between serum levels of biomarkers and RP as well as neurosensory manifestations, graded by the International Consensus Criteria. Generalized linear models with adjustment for possible confounders were also used for associations between serum levels of biomarkers and; (1) severity of RP recorded as the extent of finger blanching calculated with Griffin score, (2) vibration perception thresholds, (3) magnitude of current exposure as [A(8); (m/s2)] value, and (4) the duration of exposure in years. Serum levels of thrombomodulin, von Willebrand factor, calcitonin gene related peptide (CGRP), heat shock protein 27, and caspase-3 were positively associated with severity of RP. Serum levels of CGRP were positively associated with the neurosensory component. No associations with exposure were shown for these biomarkers. For Intercellular adhesion molecule 1 and monocyte chemoattractant protein 1, no associations were found with neither severity nor exposure. Levels of serum biomarkers associated with endothelial injury or dysfunction, inflammation, vasodilation, neuroprotection, and apoptosis were positively associated with the severity of hand-arm vibration injury.

UNASSIGNED: Elevated ambient pollution exposure is potentially linked to thromboembolism. However, the mechanisms by which particulate matter (PM) interferes with the balance of hemostatic system remain unclear. This study investigates PM-mediated hemostatic changes in individuals across unique seasonal variations of ambient pollution.
UNASSIGNED: This prospective study was conducted between February and July 2020 during alterations in ambient pollution in Chiang Mai, Thailand. Blood tests from 30 healthy subjects were assessed at four-week intervals, four times in total. Various coagulation tests, including prothrombin time (PT), activated partial thromboplastin time (aPTT), von Willebrand factor (vWF), platelet count, and platelet functions, were evaluated. A mixed-effects model was used to analyze the impact of high PM2.5 and PM10 on hemostatic parameters.
UNASSIGNED: Thirty male subjects with mean age of 38.9 ± 8.2 years, were included. High levels of PM2.5 and PM10 were significantly associated with PT shortening, with no such effect observed in aPTT. PM2.5 and PM10 values also positively correlated with vWF function, while vWF antigen levels remained unchanged. Soluble P-selectin showed a strong positive association with PM2.5 and PM10 levels. Platelet function analysis revealed no correlation with PM values.
UNASSIGNED: Short-term exposure to elevated PM2.5 and PM10 concentrations was linked to shortened PT and enhanced vWF function in healthy individuals. Exploring the impact of these changes on clinically relevant thrombosis is crucial. Additional studies on the pathogenesis of pollution-related thrombosis are warranted for maintaining good health.

von Willebrand disease (VWD) is the most common inherited bleeding disorder. The disorder is characterized by excessive mucocutaneous bleeding. The most common bleeding manifestations of this condition include nosebleeds, bruising, bleeding from minor wounds, menorrhagia or postpartum bleeding in women as well as bleeding after surgery. Other less frequent symptoms include gastrointestinal bleeding, haematomas or haemarthroses. VWD pathophysiology is complex and results from defects in von Willebrand factor (VWF) glycoprotein. Quantitative deficiencies are responsible for type 1 VWD with a partial decrease of VWF and type 3 with the complete absence of VWF. Qualitative abnormalities cause type 2 VWD, being further divided into types 2A, 2B, 2M and 2N. Although common, VWD is at risk of misdiagnosis, overdiagnosis and underdiagnosis owing to several factors, including complex diagnosis, variability of bleeding symptoms, presence of external variables (blood groups and other physiological modifiers such as exercise, thyroid hormones, oestrogens, and ageing), and lack of disease awareness among non-specialist health-care providers. Establishing the correct VWD diagnosis requires an array of specialized phenotypic assays and/or molecular genetic testing of the VWF gene. The management of bleeding includes increasing endogenous VWF levels with desmopressin or infusion of exogenous VWF concentrates (plasma-derived or recombinant). Fibrinolytic inhibitors, topical haemostatic agents and hormonal therapies are used as effective adjunctive measures.

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