Hemostatic Function Research Articles

Protease-activated receptors and glycoprotein VI cooperatively drive the platelet component in thromboelastography

BackgroundThromboelastography (TEG) is used for real-time determination of hemostatic status in patients with acute risk of bleeding. Thrombin is thought to drive clotting in TEG through generation of polymerized fibrin and activation of platelets through protease-activated receptors (PARs). However, the specific role of platelet agonist receptors and signaling in TEG has not been reported. ObjectivesHere, we investigated the specific receptors and signaling pathways required for platelet function in TEG using genetic and pharmacologic inhibition of platelet proteins in mouse and human blood samples. MethodsClotting parameters (R time, α-angle [α], and maximum amplitude [MA]), were determined in recalcified, kaolin-triggered citrated blood samples using a TEG 5000 analyzer. ResultsWe confirmed the requirement of platelets, platelet contraction, and αIIbβ3 integrin function for normal α and MA. Loss of the integrin adaptor Talin1 in megakaryocytes/platelets (Talin1mKO) also reduced α and MA, but only minimal defects were observed in samples from mice lacking Rap1 GTPase signaling. PAR4mKO samples showed impaired α but normal MA. However, impaired TEG traces similar to those in platelet-depleted samples were observed with samples from PAR4mKO mice depleted of glycoprotein VI on platelets or with addition of a Syk inhibitor. We reproduced these results in human blood with combined inhibition of PAR1, PAR4, and Syk. ConclusionOur results demonstrate that standard TEG is not sensitive to platelet signaling pathways critical for integrin inside-out activation and platelet hemostatic function. Furthermore, we provide the first evidence that PARs and glycoprotein VI play redundant roles in platelet-mediated clot contraction in TEG.

Disulfide bond reduction and exchange in C4 domain of von Willebrand factor undermines platelet binding

BackgroundThe von Willebrand factor (VWF) is a key player in regulating hemostasis through adhesion of platelets to sites of vascular injury. It is a large, multi-domain, mechano-sensitive protein that is stabilized by a net of disulfide bridges. Binding to platelet integrin is achieved by the VWF-C4 domain, which exhibits a fixed fold, even under conditions of severe mechanical stress, but only if critical internal disulfide bonds are closed. ObjectiveTo determine the oxidation state of disulfide bridges in the C4 domain of VWF and implications for VWF’s platelet binding function. MethodsWe combined classical molecular dynamics and quantum mechanical simulations, mass spectrometry, site-directed mutagenesis, and platelet binding assays. ResultsWe show that 2 disulfide bonds in the VWF-C4 domain, namely the 2 major force-bearing ones, are partially reduced in human blood. Reduction leads to pronounced conformational changes within C4 that considerably affect the accessibility of the integrin-binding motif, and thereby impair integrin-mediated platelet binding. We also reveal that reduced species in the C4 domain undergo specific thiol/disulfide exchanges with the remaining disulfide bridges, in a process in which mechanical force may increase the proximity of specific reactant cysteines, further trapping C4 in a state of low integrin-binding propensity. We identify a multitude of redox states in all 6 VWF-C domains, suggesting disulfide bond reduction and swapping to be a general theme. ConclusionsOur data suggests a mechanism in which disulfide bonds dynamically swap cysteine partners and control the interaction of VWF with integrin and potentially other partners, thereby critically influencing its hemostatic function.

MP51-17 INITIAL EXPERIENCE OF TRANSURETHRAL BLUE LASER VAPORIZATION OF PROSTATE USING A NOVEL DUAL WAVELENGTH LASER SYSTEM

You have accessJournal of UrologyCME1 Apr 2023MP51-17 INITIAL EXPERIENCE OF TRANSURETHRAL BLUE LASER VAPORIZATION OF PROSTATE USING A NOVEL DUAL WAVELENGTH LASER SYSTEM Lin Yang, Zhihui Zou, Xiaofeng Xu, Weimin Gan, Liyue Mu, and Dalin He Lin YangLin Yang More articles by this author , Zhihui ZouZhihui Zou More articles by this author , Xiaofeng XuXiaofeng Xu More articles by this author , Weimin GanWeimin Gan More articles by this author , Liyue MuLiyue Mu More articles by this author , and Dalin HeDalin He More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003299.17AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Our preclinical study confirmed that compared with the commonly used 532 nm, 980 nm and 1470 nm lasers, under the same power, the 450 nm laser has the advantages of higher vaporization efficiency, thinner coagulation layer and lower noise, theoretically it’s more suitable for BPH surgery. In this study, we reported the initial experience of transurethral blue laser vaporization of prostate (BLVP). METHODS: The novel blue laser surgical system is a dual wavelength laser system, which output 450 nm laser (Max: 200 W) and 976 nm laser (Max: 50 W), which are respectively used for tissue vaporization and coagulation by foot switch. Between May and September 2022, four centers were selected to perform BLVP using this novel blue laser surgical system and photo-selective prostate vaporization (PVP) was served as control with the patients ratio of 1:1. The international prostate symptom score (IPSS), Quality of life (QoL), maximum urinary flow rate (Qmax) before and 1 month after operation were collected, and also the operation time and bleeding. The evaluation of blue and green laser surgery from 8 operators was also collected. RESULTS: Total 101 BPH patients were enrolled and 51 received BLVP, 50 received PVP, 8 cases of PVP and 3 cases of BLVP convert to transurethral resection of prostate (TURP) mainly due to uncontrollability bleeding, the other 90 patients completed the follow-up. The novel 200 W 450 nm laser vaporized visible more rapidly than PVP. In surgeons with PVP experience, they found it’s easier to perform BLVP than PVP duo to the reliable hemostatic function by 976 nm laser. In surgeons with no PVP experience, it took 3-5 operations to overcome the desire of "TURP conversion" for BLVP and 5-10 operations for PVP. There was no significant difference between the two groups in baseline data, IPSS, QoL, Qmax and bleeding before and after operation, however, there were no difference of the operation time between two groups. The mainly reason was the power of the blue laser is very strong, which can lead to "bursting" of optical fiber once touch the tissue. It took about 10-20 operations to adapt to this "non-contact" vaporization mode. CONCLUSIONS: The novel blue laser surgical system has high vaporization efficiency, rapid and reliable hemostasis, therefore safe and effectiveness, and easy to learn. Source of Funding: None © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e700 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Lin Yang More articles by this author Zhihui Zou More articles by this author Xiaofeng Xu More articles by this author Weimin Gan More articles by this author Liyue Mu More articles by this author Dalin He More articles by this author Expand All Advertisement PDF downloadLoading ...

Histone deacetylase-6 modulates the effects of 4°C platelets on vascular endothelial permeability.

Platelets (PLTs) stored at 4°C exhibit equivalent or superior hemostatic function compared with 22°C PLTs, but have shorter circulation times and a decreased ability to modulate vascular permeability. These differences may be due to morphological changes and storage-induced activation. Using a proteomics-based approach, we found that 4°C-stored PLTs express decreased α-tubulin, a key PLT structural protein. PLT activation is characterized by α-tubulin deacetylation, which is regulated by histone deacetylase-6 (HDAC-6). We hypothesized that inhibition of HDAC-6 in stored PLTs will improve their ability to regulate vascular permeability through reduced activation and α-tubulin deacetylation. In an invivo model of vascular permeability, treatment of 4°C PLTs with the HDAC-6 inhibitor tubacin enhanced the vasculoprotective properties of untreated 4°C PLTs. 4°C PLT circulation, however, was unchanged by tubacin treatment, suggesting that circulation time may not be a critical factor in determining the vasculoprotective effects of PLTs. Assessing the factor content of stored PLTs revealed that angiopoietin-1 (Ang-1) increased in 4°C PLTs over time, which was further enhanced by tubacin treatment. In addition, angiopoietin-2, an inducer of vascular leak and antagonist of Ang-1, inhibited PLT barrier protection, suggesting involvement of the Tie-2 pathway. This study demonstrates that HDAC-6 inhibition with tubacin attenuates the diminished vasculo-protective properties of 4°C PLTs, and these properties may be independent of PLT circulation time.

Comparison of the effects of probiotics, rifaximin, and lactulose in the treatment of minimal hepatic encephalopathy and gut microbiota.

Minimal hepatic encephalopathy (MHE) is an early stage in the pathogenesis of hepatic encephalopathy. Intestinal microbiota is involved in the pathogenesis of hepatic encephalopathy and has become an important therapeutic target. Since there is no unified treatment principle for MHE, this study was conducted to determine the safety and efficacy of different intestinal microecological modulators in the treatment of MHE, and to explore the potential mechanism through intestinal microbiota analysis. Patients with liver cirrhosis were screened for MHE using psychometric hepatic encephalopathy score test. Patients diagnosed with MHE were enrolled and received probiotics, rifaximin, or lactulose for 4 weeks. Adverse events were recorded. The psychometric hepatic encephalopathy score test was performed after treatment. Samples of blood and stool were collected at entry and 4 weeks. Blood samples were analyzed to assess blood ammonia, liver, kidney, and hemostatic functions. Stool microbiota were sequenced to confirm changes in microbial composition. Of 323 patients with liver cirrhosis, 74 patients were diagnosed with MHE. In all, 54 patients were enrolled and 52 who agree to follow-up were included in analysis. The recovery rates of MHE patients received probiotics, rifaximin, and lactulose were 58.8% (20/34), 45.5% (5/11), and 57.1% (4/7), respectively. Probiotics and rifaximin improved liver function in MHE patients to a certain extent. Taxonomic compositions of gut microbiota in MHE patients were distinct from healthy people before treatment; the differences were significantly reduced after treatment, and the gut microbiota gradually resembled the structure of healthy individuals. We found that the relative abundance of specific taxa associated with anti-inflammatory and good cognitive functions was increased in MHE patients after treatment. Accordingly, metabolic pathways in MHE patients were altered before and after treatment. Downregulated pathways after probiotics treatment included glycometabolism and degradation of aromatic compounds. After lactulose treatment, degradation pathways of arginine and ornithine showed a downward trend. Probiotics, rifaximin, and lactulose are safe and effective in the treatment of MHE, and improve the composition of gut microbiota to some extent.

Platelet glycoprotein V spatio-temporally controls fibrin formation

The activation of platelets and coagulation at vascular injury sites is crucial for hemostasis but can promote thrombosis and inflammation in vascular pathologies. Here, we delineate an unexpected spatio-temporal control mechanism of thrombin activity that is platelet orchestrated and locally limits excessive fibrin formation after initial hemostatic platelet deposition. During platelet activation, the abundant platelet glycoprotein (GP)V is cleaved by thrombin. We demonstrate, with genetic and pharmacological approaches, that thrombin-mediated shedding of GPV does not primarily regulate platelet activation in thrombus formation but rather has a distinct function after platelet deposition and specifically limits thrombin-dependent generation of fibrin, a crucial mediator of vascular thrombo-inflammation. Genetic or pharmacologic defects in hemostatic platelet function are unexpectedly attenuated by specific blockade of GPV shedding, indicating that the spatio-temporal control of thrombin-dependent fibrin generation also represents a potential therapeutic target to improve hemostasis.

Paired Analysis of D-Dimer and Its Correlated Hemostatic Parameters in 30 Dogs with Neoplasms after Tumorectomy

Previous studies have reported that dogs with neoplasms had elevated D-dimer levels. However, few studies have addressed whether D-dimer could be an indicator of tumor burden. The clinical significance of paired analysis of pre- and post-operation of D-dimer levels in dogs has rarely been described. The present study investigated the values of D-dimer levels and their correlated hemostatic alterations in dogs with surgically removable benign and malignant tumors. This study analyzed 30 clinically healthy and 30 tumor-bearing dogs and evaluated the hemostatic functions including D-dimer, thromboelastography G (TEG G), fibrinogen, activated partial thromboplastin time (aPTT), prothrombin time, and platelet count. The median level of pre-treatment D-dimer was 0.8 µg/mL (range: 0.1-6.3 µg/mL), whereas the control dogs exhibited a median value of 0.1 µg/mL (range: 0.1-0.1 µg/mL, p < 0.0001). After tumorectomy, the median levels of D-dimer (p < 0.0001), fibrinogen (p < 0.0001), TEG G value (p < 0.01), and aPTT (p < 0.05) were significantly lower than those of the pre-treatment samples. However, further studies are needed to clarify the values of other hemostatic evaluations. The study revealed the clinical significance of D-dimer and its correlated hemostatic parameters by paired analysis in dogs with tumors. Though more cases are needed for solid confirmation, these values could be potential tumor biomarkers for dogs.

Comprehensive multiparameter evaluation of platelet function using a highly sensitive membrane capacitance sensor

An accurate and comprehensive assessment of platelet function is essential for managing patients who receive antiplatelet therapies or require platelet transfusion either for treating active bleeding or for prophylaxis. Platelets contribute to clotting by undergoing a series of highly regulated functional responses including adhesion, spreading, granular secretion, aggregation, and cytoskeletal contraction. However, current platelet function assays evaluate only partial aspects of this intricate process and often under non-physiological testing conditions. Herein, we describe the development of a new approach to measure multiple key platelet function-related parameters, in a more physiologically relevant ex vivo semi-rigid microenvironment using a membrane capacitance sensor (MCS). MCS response to clotting provided three sensing parameters with sensitivities towards platelet counts, stimulation strengths, and activation pathways. Live confocal fluorescent imaging of stimulated platelets on MCS suggests that the presented system can readily and accurately convert the dynamics of cytoskeletal reorganization into analyzable electrical signals. Together, this new completely electrical sensing platform can be a promising diagnostic venue to recognize the impairment of primary hemostatic functions, evaluate the efficacy of therapeutic interventions, and gain further insights into the mechanisms of platelets in hemostasis and thrombosis.

Endothelial dysfunction in a general practitioner’s work

Endothelial dysfunction (ED) is a pathological condition that is impairment in the synthesis of endothelial factors and is a major component in the pathogenesis of many diseases, including those of a therapeutic profile. Many specialists now consider ED as a universal component in the development of cardiovascular and respiratory diseases. The paper contains information about the main functions of the endothelium and their impact on the organs and systems of the body, the state of microhemocirculation, and the entire internal environment. It also considers ED that affects vasomotor, hemostatic, adhesive, and angiogenic functions and the main markers of endothelial damage. The possibilities of preventive measures and pharmacological correction of ED are discussed.

The interplay between hypovitaminosis D and the immune dysfunction in the arteriovenous thrombotic complications of the sever coronavirus disease 2019 (COVID-19) infection.

Thromboembolic complications including cerebrovascular accidents, pulmonary embolism, myocardial infarction, deep vein thrombosis and disseminating intravascular coagulopathy are serious encounters in sever coronavirus disease 2019 (COVID-19) infected patients. This worsens the prognosis and may lead to death or life long morbidities. The laboratory finding of the disturbed haemostasias and the hyperinflammatory response are almost invariably present in COVID-19 patients. Multiple treatment modalities are utilized by the healthcare professionals to overcome the cytokine storm, oxidative stress, endothelial dysfunction, and coagulopathy in these patients. The combined actions of vitamin D (VitD) as a steroid hormone with anti-inflammatory, immunomodulatory, and antithrombotic properties increase the potential of the possible involvement of hypovitaminosis D in the thromboembolic complications of COVID-19 infection, and stimulated researchers and physicians to administer VitD therapy to prevent the infection and/or overcome the disease complications. The current review highlighted the immunomodulatory, anti-inflammatory, antioxidative and hemostatic functions of VitD and its interrelation with the renin-angiotensin-aldosterone system (RAAS) pathway and the complement system. Additionally, the association of VitD deficiency with the incidence and progression of COVID-19 infection and the associated cytokine storm, oxidative stress, hypercoagulability, and endothelial dysfunction were emphasized. Normalizing VitD levels by daily low dose therapy in patients with hypovitaminosis D below (25 nmol/l) is essential for a balanced immune response and maintaining the health of the pulmonary epithelium. It protects against upper respiratory tract infections and decreases the complications of COVID-19 infections. Understanding the role of VitD and its associated molecules in the protection against the coagulopathy, vasculopathy, inflammation, oxidative stress and endothelial dysfunction in COVID-19 infection could lead to new therapeutic strategies to prevent, treat, and limit the complications of this deadly virus infection.

Platelet count, temperature and pH value differentially affect hemostatic and immunomodulatory functions of platelets

Platelets are primarily recognized for their role in hemostasis, but also regulate immune responses by interacting with leukocytes. Their highly sensitive nature enables platelets to rapidly respond to micro-environmental changes, which is crucial under physiological condition but can jeopardize in vitro analyses. Thus, we tested how platelet count and changes in pH and temperatures, which are commonly experienced during inflammation and infection but also affected by ex vivo analyses, influence platelet-leukocyte interaction and immunomodulation.Reducing platelet count by up to 90 % slightly decreased platelet activation and platelet-leukocyte aggregate formation, but did not affect CD11b activation nor CD62L shedding of monocytes or neutrophils. Acidosis (pH 6.9) slightly elevated platelet degranulation and binding to innate leukocytes, though pH changes did not modulate leukocyte activation. While platelet responsiveness was higher at room temperature than at 37 °C, incubation temperature did not affect platelet-leukocyte aggregate formation. In contrast, platelet-mediated CD11b activation and CD62L expression increased with temperature.Our data thus demonstrate the importance of standardized protocols for sample preparation and assay procedure to obtain comparable data. Further, unspecific physiologic responses such as thrombocytopenia, acidosis or temperature changes may contribute to platelet dysfunction and altered platelet-mediated immunomodulation in inflammatory and infectious disease.

High fragmentation in platelet concentrates impacts the activation, procoagulant, and aggregatory capacity of platelets

Platelets are transfused to patients to prevent bleeding. Since both preparation and storage can impact the hemostatic functions of platelets, we studied platelet concentrates (PCs) with different initial composition in regard to platelet fragmentation and its impact on storage-induced changes in activation potential. Ten whole blood derived PCs were assessed over 7 storage days. Using flow cytometry, platelet (CD41+) subpopulations were characterized for activation potential using activation markers (PAC-1, P-selectin, and LAMP-1), phosphatidylserine (Annexin V), and mitochondrial integrity (DiIC1(5)). Aggregation response, coagulation, and soluble activation markers (cytokines and sGPVI) were also measured. Of the CD41+ events, the PCs contained a median of 82% normal-sized platelets, 10% small platelets, and 8% fragments. The small platelets exhibited procoagulant hallmarks (increased P-selectin and Annexin V and reduced DiIC1(5)). Normal-sized platelets responded to activation, whereas activation potential was decreased for small and abolished for fragments. Five PCs contained a high proportion of small platelets and fragments (median of 28% of CD41+ events), which was significantly higher than the other five PCs (median of 9%). A high proportion of small platelets and fragments was associated with procoagulant hallmarks and decreased activation potential, but, although diminished, they still retained some activation potential throughout 7 days storage.

Relationship Blood Gas Analysis And Hemostasis Physics In Multiple Trauma Patients In Adam Malik Hospital Medan

Introduction: Trauma is currently the most common cause of death in the first four decades of life and is still a major public health problem in every country. Arterial blood gas analysis (AGDA) is known to be an important marker for poor patient outcomes and occult or compensatory hypoperfusion. This study also evaluated the relationship and influence of AGDA scores on the outcome and prognosis of patients with multiple trauma. The results of this study will be able to assist in the rapid triage of acute trauma patients, which will also help identify high-risk patients who develop severe complications.&#x0D; Method: This study assessed the relationship between initial arterial blood gas and initial hemostatic function in acute trauma patients who came to the emergency department at H. Adam Malik General Hospital Medan. This type of research is a retrospective analytic where data is taken from medical records to see the relationship between AGDA and coagulation profile in multiple trauma patients at H. Adam Malik General Hospital Medan. After recruiting research samples at Adam Malik Haji Center General Hospital Medan, it was found that 141 multiple trauma patients who underwent surgery at H. Adam Malik General Hospital Medan met the inclusion criteria and were not included in the exclusion criteria&#x0D; Results: In this study, there were significant results between the pH and the three hemostatic physiology, there were no significant results between pCO2 and the three hemostatic physiology, and there were significant results between the HCO3 value and the PT and INR values, but no significant results were obtained with the APTT. Some authors believe that arterial PCO2 at admission is a significant prognostic factor in patients with traumatic head injury, but several studies dispute the arterial blood gas (ABG) parameter as a reliable indicator of short-term outcome in these patients. The main goal of the management of critically ill patients is the maintenance and optimization of cellular (and organ) health.&#x0D; Conclusion: This goal can be achieved by maintaining oxygenation, perfusion, fluid, electrolyte, and acid-base balance. Acid-base and oxygenation disorders are also critical, especially when these disorders develop rapidly.

Platelet functions in tethered heifers in the process of growing them

In the course of growing heifers on tethered content, there is a tendency to some decrease in the severity of platelet lipid peroxidation due to an increase in their antioxidant protection. In platelets, this is accompanied by activation of the actin-myosin system, a high level of adenosine phosphates, and their intense secretion in the case of platelet participation in hemostasis. The observed heifers showed a tendency to increase the hemostatic functions of platelets, manifested in the blood and in vitro. The revealed slight increase in platelet activity in tethered heifers is caused by maturation during rearing of surface and intracellular mechanisms of platelet participation in hemostasis and microcirculation processes.

ФУНКЦИОНАЛЬНАЯ АКТИВНОСТЬ ЭНДОТЕЛИЯ В СИСТЕМНОМ И МЕСТНОМ КРОВОТОКЕ У ПАЦИЕНТОВ ОБЛИТЕРИРУЮЩИМ АТЕРОСКЛЕРОЗОМ И РАЗВИТИЕ РЕСТЕНОЗА ПОСЛЕ ОПЕРАЦИИ БЕДРЕННО-ПОДКОЛЕННОГО ШУНТИРОВАНИЯ

Objective: To analyze the role of markers of the endothelial dysfunction in the vessels of the systemic and local blood flow before and after femoropopliteal bypass surgery (FPBS) in the development of restenosis at obliterating lesions of the femoropopliteal arterial segment (FPAS). Methods: The results of the examination and treatment of 82 patients with obliterating atherosclerosis who underwent FPBS were analyzed. Before and after surgery they underwent testing for serum homocysteine, oxidized low-density lipoprotein, soluble vascular cell adhesion molecule-1 (sVCAM-1), plasminogen activator inhibitor-1 (PAI-1), tissue-type plasminogen activator (t-PA), and annexin V in the systemic and local blood flow. Based on the condition of the reconstruction zone after 12 months, all patients were divided into two groups. Group 1 included patients without restenosis (n=21), and Group 2 – with restenosis (n=61). Results: Before surgery Group 2 patients showed significant differences in the severity of adhesive and hemostatic forms of endothelial dysfunction, as well as apoptosis in comparison with Group 1. It was found that before surgery, Group 2 patients had a significantly higher level of sVCAM-1 in the local bloodstream (by 37.5%, p=0.014), PAI-1 in the systemic and local bloodstream (by 15.6%, p=0.010, and by 16.4%, p=0.008 respectively) and annexin V in the systemic and local bloodstream (by 48.9%, p=0.012 and by 60.2%, p=0.002 respectively). After surgery Group 2 patients had significantly higher levels of PAI-1 in the systemic (by 18.9%, p=0.004) and local (by 11.1%, p=0.049) blood flow, and annexin V in the systemic circulation (by 28.4%, p=0.011) compared with Group 1. Thus increased levels of sVCAM-1 in the local bloodstream, PAI-1, and annexin V – in the systemic and local bloodstream before surgery were associated with postoperative development of restenosis, while higher values of PAI-1 in the systemic and local bloodstream and annexin V in the systemic circulation after surgery were related to subsequent restenosis development. Conclusion: The results of the study indicate impairment of the adhesive and hemostatic function of the endothelium, and increased level of apoptosis in the blood vessels of systemic and local blood flow in patients with restenosis, which can be used to develop personalized approach to management of this disorder and improve the results of revascularization interventions on FPAS. Keywords: Obliterating atherosclerosis of the lower extremities, femoropopliteal bypass surgery, functional activity of the endothelium, restenosis.

Polyphosphate as an antithrombotic target and hemostatic agent.

Polyphosphate (PolyP) is a polymer comprised of linear phosphate units connected by phosphate anhydride bonds. PolyP exists in a diverse range of eukaryotes and prokaryotes with varied chain lengths ranging from six to thousands of phosphate units. Upon activation, human platelets and neutrophils release short-chain PolyP, along with other components, to initiate the coagulation pathway. Long-chain PolyP derived from cellular or bacterial organelles exhibits higher proinflammatory and procoagulant effects compared to short-chain PolyP. Notably, PolyP has been identified as a low-hemorrhagic antithrombotic target since neutralizing plasma PolyP suppresses the thrombotic process without impairing the hemostatic functions. As an inorganic polymer without uniform steric configuration, PolyP is typically targeted by cationic polymers or recombinant polyphosphatases rather than conventional antibodies, small-molecule compounds, or peptides. Additionally, because of its procoagulant property, PolyP has been incorporated in wound-dressing materials to facilitate blood hemostasis. This review summarizes current studies on PolyP as a low-hemorrhagic antithrombotic target and the development of hemostatic materials based on PolyP.

Efficacy of phytotherapy as nutritional supplements in patients with refractory immune thrombocytopenia

IntroductionThe management of refractory immune thrombocytopenia (ITP) is challenging and difficult. The treatment was mainly comprised of cytotoxic and immunosuppressed drugs that rarely lead to long-term remission but potentially cause severe and dangerous side effects. Our current study is a retrospective clinical analysis of refractory ITP patients who underwent phytotherapy as nutritional supplements. MethodsA retrospective clinical analysis of 15 refractory immune thrombocytopenia (ITP) patients aged 12–64 with ITP history for more than 24 months before the enrollments. All patients presented with low platelet count (< 30 × 109/L) and moderate to severe bleeding symptoms such as extensive petechiae, bruising, epistaxis, prolonged menses, rectal bleeding, and hematuria. The patients underwent supportive phytotherapy as nutritional supplements using herbal extracts with hemostatic, immunomodulating, and platelet function augmenting functions ResultsThe 6-month retrospective clinical evaluation indicated that phytotherapy might offer an effective and safe solution for controlling bleeding symptoms and improving platelet counts for refractory ITP patients. Moreover, phytotherapy also significantly improved patients' red cell count, hemoglobulin, and liver enzyme levels compared to baseline data. ConclusionsIn individual cases and economically disadvantaged regions, investigating and applying an appropriate combination of phytotherapy based on scientific knowledge and traditional folk medical experiences might offer an effective, inexpensive, and safe solution for refractory ITP and other bleeding disorders.

Impaired Platelet Function and Thrombus Formation in PDE5A-Deficient Mice.

Intracellular cyclic GMP (cGMP) inhibits platelet function. Platelet cGMP levels are controlled by phosphodiesterase 5A (PDE5A)-mediated degradation. However, the exact role of PDE5A in platelet function and thrombus formation remains poorly understood. In this study, we characterized the role of PDE5A in platelet activation and function. Platelets were isolated from wild type or PDE5A-/- mice to measure platelet aggregation, activation, phosphatidylserine exposure (annexin-V binding), reactive oxygen species (ROS) generation, platelet spreading as well as clot retraction. Cytosolic calcium mobilization was measured using Fluo-4 AM by a microplate reader. Western blot was used to measure the phosphorylation of VASP, ERK1/2, p38, JNK, and AKT. FeCl3-induced arterial thrombosis and venous thrombosis were assessed to evaluate the in vivo hemostatic function and thrombus formation. Additionally, in vitro thrombus formation was assessed in a microfluidic whole-blood perfusion assay. PDE5A-deficient mice presented significantly prolonged tail bleeding time and delayed arterial and venous thrombus formation. PDE5A deficiency significantly inhibited platelet aggregation, ATP release, P-selectin expression, and integrin aIIbb3 activation. In addition, an impaired spreading on collagen or fibrinogen and clot retraction was observed in PDE5A-deficient platelets. Moreover, PDE5A deficiency reduced phosphatidylserine exposure, calcium mobilization, ROS production, and increased intracellular cGMP level along with elevated VASP phosphorylation and reduced phosphorylation of ERK1/2, p38, JNK, and AKT. In conclusion, PDE5A modulates platelet activation and function and thrombus formation, indicating that therapeutically targeting it might be beneficial for the treatment of thrombotic diseases.

A perfect storm: acute portal vein thrombosis in a patient with severe dengue and hemorrhagic manifestations—a case report

BackgroundDengue constitutes a public health problem in endemic regions. The clinical course can range from asymptomatic to severe expressions. Hemorrhagic manifestations are the most frequently reported complications; on the contrary, thrombotic complications are unusual.Clinical caseWe present the case of an adult patient who presented hemodynamic instability, severe thrombocytopenia, and positive serology for dengue, in whom acute portal vein thrombosis was documented. The possible pathophysiology of thrombocytopenia and thrombosis in dengue is discussed, as well as the dilemmas regarding the treatment of associated hemorrhagic and thrombotic manifestations.ConclusionsThe present case brings up the importance of considering the possibility of thrombotic events in patients with severe dengue. A high degree of suspicion, close assessment of hemostatic function, and quality supportive care are essential to improve outcomes. To our knowledge, this is the first report of dengue-associated portal vein thrombosis.

Gelsolin Modulates Platelet Dense Granule Secretion and Hemostasis via the Actin Cytoskeleton

The mechanisms underlying platelet granule release are not fully understood. The actin cytoskeleton serves as the platelet's structural framework that is remodeled upon platelet activation. Gelsolin is a calcium-dependent protein that severs and caps existing actin filaments although its role in modulating platelet granule exocytosis is unknown. The hemostatic function of wild-type (WT) and gelsolin null (Gsn-/- ) mice was measured ex vivo by rotational thromboelastometry analysis of whole blood. Platelets were purified from WT and Gsn-/- mouse blood and activated with thrombin. Platelet aggregation was assessed by light-transmission aggregometry. Clot retraction was measured to assess outside-in integrin signaling. Adenosine triphosphate (ATP) release and surface P-selectin were measured as markers of dense- and α-granule secretion, respectively. The kinetics of agonist-induced aggregation, clot retraction, and ATP release were accelerated in Gsn-/- platelets relative to WT. However, levels of surface P-selectin were diminished in Gsn-/- platelets. ATP release was also accelerated in WT platelets pretreated with the actin-depolymerizing drug cytochalasin D, thus mimicking the kinetics observed in Gsn-/- platelets. Conversely, ATP release kinetics were normalized in Gsn-/- platelets treated with the actin polymerization agonist jasplakinolide. Rab27b and Munc13-4 are vesicle-priming proteins known to promote dense granule secretion. Co-immunoprecipitation indicates that the association between Rab27b and Munc13-4 is enhanced in Gsn-/- platelets. Gelsolin regulates the kinetics of hemostasis by modulating the platelet's actin cytoskeleton and the protein machinery of dense granule exocytosis.