primary hemostasis
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Toxins ◽  
2022 ◽  
Vol 14 (1) ◽  
pp. 37
Author(s):  
Lucas Ian Veloso Correia ◽  
Fernanda Van Petten de Vasconcelos Azevedo ◽  
Fernanda Gobbi Amorim ◽  
Sarah Natalie Cirilo Gimenes ◽  
Lorena Polloni ◽  
...  

Some species of primitive predatory ants, despite living in a colony, exercise their hunting collection strategy individually; their venom is painful, paralyzing, digestive, and lethal for their prey, yet the toxins responsible for these effects are poorly known. Ectatomma opaciventre is a previously unrecorded solitary hunting ant from the Brazilian Cerrado. To overcome this hindrance, the present study performed the in vitro enzymatic, biochemical, and biological activities of E. opaciventre to better understand the properties of this venom. Its venom showed several proteins with masses ranging from 1–116 kDa, highlighting the complexity of this venom. Compounds with high enzymatic activity were described, elucidating different enzyme classes present in the venom, with the presence of the first L-amino acid oxidase in Hymenoptera venoms being reported. Its crude venom contributes to a state of blood incoagulability, acting on primary hemostasis, inhibiting collagen-induced platelet aggregation, and operating on the fibrinolysis of loose red clots. Furthermore, the E. opaciventre venom preferentially induced cytotoxic effects on lung cancer cell lines and three different species of Leishmania. These data shed a comprehensive portrait of enzymatic components, biochemical and biological effects in vitro, opening perspectives for bio-pharmacological application of E. opaciventre venom molecules.


2021 ◽  
Vol 11 (1) ◽  
pp. 212
Author(s):  
Laurent Dietrich ◽  
Marion Kibler ◽  
Kensuke Matsushita ◽  
Benjamin Marchandot ◽  
Antonin Trimaille ◽  
...  

Background: Bleeding events are among the striking complications following transcatheter aortic valve replacement (TAVR), and bleeding prediction models are crucially warranted. Several studies have highlighted that primary hemostasis disorders secondary to persistent loss of high-molecular-weight (HMW) multimers of the von Willebrand factor (vWF) and assessed by adenosine diphosphate closure time (CT-ADP) may be a strong predictor of late major/life-threatening bleeding complications (MLBCs). Pre-existing atrial fibrillation (AF) is a frequent comorbidity in TAVR patients and potentially associated with increased bleeding events after the procedure. Objectives: This study evaluated the impact of ongoing primary hemostasis disorders, as assessed by post-procedural CT-ADP > 180 s, on clinical events after TAVR among anticoagulated AF patients. Methods: An ongoing primary hemostasis disorder was defined by post-procedure CT-ADP > 180 s. Bleeding complications were assessed according to the Valve Academic Research Consortium-2 (VARC-2) criteria. The primary endpoint was the occurrence of late MLBCs at one-year follow-up. The secondary endpoint was a composite of mortality, stroke, myocardial infarction, and rehospitalization for heart failure. Results: In total, 384 TAVR patients were included in the analysis. Of these patients, 57 patients (14.8%) had a prolongated CT-ADP > 180 s. Increased MLBCs were observed in patients with CT-ADP > 180 s (35.1% versus 1.2%; p < 0.0001). Conversely, the occurrence of the composite endpoint did not differ between the groups. Multivariate analysis identified CT-ADP > 180 s (HR 28.93; 95% CI 9.74–85.95; p < 0.0001), bleeding history, paradoxical aortic stenosis (AS), and major vascular complications following TAVR as independent predictors of late MLBCs. Conclusion: Among patients with anticoagulated AF, a post-procedural CT-ADP > 180 s was identified as a strong independent predictor of late MLBCs. These findings suggest that persistent primary hemostasis disorders contribute to a higher risk of late bleeding events and should be considered for a tailored, risk-adjusted antithrombotic therapy after TAVR.


2021 ◽  
pp. 25-29
Author(s):  
N. F. Plavunov ◽  
V. A. Kadyshev ◽  
N. A. Goncharova ◽  
T. A. Bataev ◽  
I. M. Afanasov

The alternative use of local hemostatic agents based on chitosan is the gentlest method of stopping bleeding, with minimal damaging effect on tissues, in comparison with the imposition of a hemostatic tourniquet or a pressure bandage.Goal. To evaluate the effectiveness of temporary stopping of external bleeding with the help of local hemostatic agents based on chitosan in powder and bandage forms and to determine the expediency of their use by visiting ambulance teams.Materials and methods. Specialists of the field teams of Ambulance and Medical Emergency Care Station n. a. A. S. Puchkov (Moscow, Russia) used local hemostatic agents based on chitosan in the form of a powder, a bandage in comparison with traditional hemostatic agents (a hemostatic tourniquet to stop arterial bleeding and a pressure bandage). The criteria for hemostasis were the absence of wetting of the pressure bandage and the absence of the need for a hemostatic tourniquet.Results. 103 patients were included in the main group, and 106 patients with arterial and venous bleeding from wounds of various localization were included in the control group. The age of patients in the compared groups ranged from 18 to 94 years. When using hemostatic powder and bandage, primary hemostasis was achieved in 99 patients in 96.1 % of cases, compared with the control group in 76 patients in 67.9 % of cases.Conclusions. Simplicity and ease of use, the speed of stopping bleeding and achieving results, as well as the absence of the need for special skills among specialists in the use of hemostatic agents, improved the quality of emergency medical care for patients with bleeding and allowed them to be recommended as a dressing for emergency medical care.


Hematology ◽  
2021 ◽  
Vol 2021 (1) ◽  
pp. 85-91
Author(s):  
Kristi J. Smock ◽  
Karen A. Moser

Abstract Bleeding disorders with normal, borderline, or nondiagnostic coagulation tests represent a diagnostic challenge. Disorders of primary hemostasis can be further evaluated by additional platelet function testing modalities, platelet electron microscopy, repeat von Willebrand disease testing, and specialized von Willebrand factor testing beyond the usual initial panel. Secondary hemostasis is further evaluated by coagulation factor assays, and factor XIII assays are used to diagnose disorders of fibrin clot stabilization. Fibrinolytic disorders are particularly difficult to diagnose with current testing options. A significant number of patients remain unclassified after thorough testing; most unclassified patients have a clinically mild bleeding phenotype, and many may have undiagnosed platelet function disorders. High-throughput genetic testing using large gene panels for bleeding disorders may allow diagnosis of a larger number of these patients in the future, but more study is needed. A logical laboratory workup in the context of the clinical setting and with a high level of expertise regarding test interpretation and limitations facilitates a diagnosis for as many patients as possible.


Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 2072-2072
Author(s):  
Sally Azer ◽  
Oluwamayokun Oshinowo ◽  
Meredith E. Fay ◽  
Yumiko Sakurai ◽  
Yongzhi Qiu ◽  
...  

Abstract A subset of patients with chronic bleeding remain undiagnosed even after extensive diagnostic evaluation are labeled as "bleeding of unknown cause" (BUC). The key barrier to treating these patients is that they have a clinical bleeding tendency in the presence of normal diagnostic tests, and optimal methods for monitoring and treating patients with BUC remain unknown. While patients with BUC have symptoms of a primary hemostatic disorder, there is no diagnostic test or biomarker that can accurately identify which patients are at risk for bleeding such as those with mild Von Willebrand Disease (VWD) which comprise a broad spectrum of patients with varying degrees of bleeding. In order to fill this diagnostic gap in disorders of primary hemostasis, there is a clinical need for more assays of platelet function. To that end, we have engineered multiple new biophysical assays to assess disorders of primary hemostasis and apply this panel of platelet function testing to potentially define new bleeding disorders, characterize platelet phenotypes in patients with BUC, and refine the definition of mild VWD. Our panel of platelet function tests (Fig 1) collectively enables us to simultaneously assess different facets of primary hemostasis from the microscopic level of single-platelet physiology to hemostatic plug formation, thereby capturing various aspects of platelet function with a single blood sample. Our platelet function panel ranges from platelet adhesion and bulk clot contraction assays to spatially-regulated platelet granule secretion assay, single-platelet contraction cytometry, microfluidics, and a microengineered vascularized bleeding model. As such, we are leveraging these biophysical assays to correlate platelet function with bleeding phenotype severity and establish the dynamic range of this diagnostic panel. We have now established that our assays can be utilized to study blood samples from patients with disorders including hemophilia A, Hermansky-Pudlak Syndrome, FLI-1 mutation, and sickle cell disease among others (Fig 2), demonstrating the clinical utility of our platelet function panel. Our panel can also be used to assess the effects of novel therapeutics on different aspects of platelet function simultaneously. To investigate how crizanlizumab (p-selectin inhibitor) affects hemostatic plug formation, healthy human blood was treated with crizanlizumab. Platelet α-granule secretion enables exposure of P-selectin, and with crizanlizumab we observed restricted platelet filopodial extension and diminished α-granule exocytosis, and an overall decrease in adhered platelets to the fibrinogen micropattern (Fig 3A). The adhesion assay demonstrated a decrease in spreading and adhesion of platelets to collagen and fibrinogen with treatment (Fig 3B). Using the bleeding model, hemostasis was achieved within the normal established range and platelets contracted normally. This suggests that p-selectin has a limited role in the setting of minor injury. Utilizing the bulk contraction assay, we exhibited increased contraction early in clot formation, however over time the treated platelets contracted similarly to the control (Fig 3C). Interestingly, the effect of crizanlizumab-induced restriction of filopodial extension did not correlate with impaired bulk clot contraction or time to form hemostatic plug. Our work suggests crizanlizumab affects platelet spreading at the single-cell level but does not impair platelet function in achieving primary hemostasis at the whole blood level. Here we demonstrate the translational utility of our platelet function panel in providing a deeper understanding of platelet biophysics as it relates to hematologic conditions, with implications for investigation to include pharmaceutical applications. The versatility of this novel panel in capturing platelet function from single-platelet contraction to providing in vitro models with the bleeding device provides multiple dimensions to platelet investigation for primary hemostatic disorders and BUC that have not yet been elucidated. Ongoing research is being conducted using our comprehensive platelet function panel to investigate platelet properties in BUC and mild VWD and correlate these biophysics with bleeding phenotypes. Using this approach we aim to provide novel diagnostic testing with clinical relevance for disorders that have been incompletely characterized until now. Figure 1 Figure 1. Disclosures Meeks: National Institutes of Health: Research Funding; Hemophilia of Georgia: Research Funding; National Hemophilia Foundation: Research Funding; Spark Therapeutics: Consultancy; Sangamo Therapeutics: Consultancy; Pfizer: Consultancy; Sanofi: Consultancy; CSL Behring: Consultancy; Genentech: Consultancy; Takeda: Consultancy. Lam: Sanguina, Inc.: Current holder of individual stocks in a privately-held company.


Author(s):  
Christine Lodberg Hvas ◽  
Julie Brogaard Larsen ◽  
Kasper Adelborg ◽  
Steffen Christensen ◽  
Anne-Mette Hvas

AbstractPatients admitted to the intensive care unit (ICU) with coronavirus disease 2019 (COVID-19), the infectious pathology caused by severe acute respiratory syndrome coronavirus 2, have a high risk of thrombosis, though the precise mechanisms behind this remain unclarified. A systematic literature search in PubMed and EMBASE identified 18 prospective studies applying dynamic coagulation assays in ICU COVID-19 patients. Overall, these studies revealed normal or slightly reduced primary hemostasis, prolonged clot initiation, but increased clot firmness. Thrombin generation assay parameters generally were equivalent to the control groups or within reference range. Fibrinolysis assays showed increased clot resistance. Only six studies related their findings to clinical outcome. We also prospectively included 51 COVID-19 patients admitted to the ICU. Blood samples were examined on day 1, 3–4, and 7–8 with platelet function tests, rotational thromboelastometry (ROTEM), in vivo and ex vivo thrombin generation, and clot lysis assay. Data on thrombosis, bleeding, and mortality were recorded during 30 days. Primary hemostasis was comparable to healthy controls, but COVID-19 patients had longer ROTEM-clotting times and higher maximum clot firmness than healthy controls. Ex vivo thrombin generation was similar to that of healthy controls while in vivo thrombin generation markers, thrombin–antithrombin (TAT) complex, and prothrombin fragment 1 + 2 (F1 + 2) were higher in ICU COVID-19 patients than in healthy controls. Impaired fibrinolysis was present at all time points. TAT complex and F1 + 2 levels were significantly higher in patients developing thrombosis (n = 16) than in those without. In conclusion, only few previous studies employed dynamic hemostasis assays in COVID-19 ICU-patients and failed to reveal a clear association with development of thrombosis. In ICU COVID-19 patients, we confirmed normal platelet aggregation, while in vivo thrombin generation was increased and fibrinolysis decreased. Thrombosis may be driven by increased thrombin formation in vivo.


Author(s):  
Anne Winther-Larsen ◽  
Birgitte Sandfeld-Paulsen ◽  
Anne-Mette Hvas

AbstractPatients with primary brain tumors have a high incidence of thrombosis and hemorrhage. The underlying mechanism is believed to be derangement of their hemostatic system. To get nearer a clarification of this, we aimed to systematically review the existing literature regarding primary and secondary hemostasis as well as fibrinolysis in patients with primary brain tumor. The review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The databases PubMed, Embase, and Web of Science were searched on December 15, 2020, without time restrictions. Studies were included if they evaluated at least one blood coagulation and/or fibrinolysis parameter in patients with primary brain cancer. In total, 26 articles including 3,288 patients were included. Overall, increased activity of secondary hemostasis was observed as increased prothrombin fragment 1 + 2 and endogenous thrombin generation levels were found in glioma patients compared with controls. Furthermore, data showed a state of hypofibrinolysis with increased plasminogen activator inhibitor 1 and prolonged clot lysis time in glioma patients. In contrast, no consistent increase in the primary hemostasis was identified; however, data suggested that increased sP-selectin could be a biomarker of increased venous thromboembolism risk and that increased platelet count may be prognostic for survival. Lastly, data indicated that fibrinogen and D-dimer could hold prognostic value. In conclusion, this review indicates that an increased activity of secondary hemostasis and impaired fibrinolysis could be important players in the pathogeneses behind the high risk of thromboembolisms observed in brain cancer patients. Thus, long-term thromboprophylaxis may be beneficial and additional studies addressing this issue are wanted.


Author(s):  
Lulu Han ◽  
Yutong Miao ◽  
Yang Zhao ◽  
Xingzhong Zhang ◽  
Xiaolong Ma ◽  
...  

Hyperhomocysteinemia (HHcy) is associated with an exaggerated platelet thrombotic response at sites of vascular injury. Here, a human medical examination report showed that elevated human plasma Hcy levels were positively correlated with enhanced blood coagulation and platelet activity, suggesting that humans with HHcy are more prone to thrombus formation at the sites of vascular injury. Accordingly, we observed accelerated platelet activation, primary hemostasis, and thrombus formation both in acute and chronic HHcy ApoE-/- mice. Upon Hcy administration in C57BL/6J mice, platelet aggregation, spreading, and clot retraction were markedly promoted. More importantly, homocysteine (Hcy) increased the affinity of platelet integrin αIIbβ3 with ligands and enhanced integrin outside-in signaling by promoting membrane phosphatidylserine (PS) exposure in vitro. Mechanistically, lipidomics analysis showed that lysophosphatidylcholines were the primary metabolites leading to clustering of HHcy-stimulated platelets. Cytosolic phospholipase A2 (cPLA2) activity and autotaxin (ATX, a secreted lysophospholipase D) secretion were upregulated by Hcy, leading to membrane phospholipid hydrolysis and PS exposure. Moreover, secreted ATX directly interacted with integrin β3. Inhibitors of cPLA2 and ATX activity blocked integrin αIIbβ3 outside-in signaling and thrombosis in HHcy ApoE-/- mice. This study identifies a novel mechanism by which HHcy promotes platelet membrane phospholipid catabolism and extracellular ATX secretion to activate integrin outside-in signaling, consequently to exaggerate thrombosis. This study reveals an innovative approach to treat HHcy-related thrombotic diseases.


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