Background: Although the use of regular replacement therapy including emicizumab for severe hemophilia has been spread, the assessment of the hemostatic ability using routine activated partial thromboplastin time (APTT) is still difficult in patients being treated with emicizumab. Methods: The hemostatic ability in patients treated with FVIII concentrate or emicizumab was evaluated by APTT, thrombin time (TT) and a small amount of tissue factor induced FIX activation assay (sTF/FIXa) using a clot waveform analysis (CWA). Results: FVIII activities based on a CWA-TT were significantly higher than those based on a CWA-APTT or chromogenic assay. FVIII activities based on the three assays in plasma without emicizumab were closely correlated, and those in plasma with emicizumab based on a CWA-TT and chromogenic assays were also closely correlated. The CWA-APTT and CWA-TT showed different patterns in patients treated with FVIII concentrates from those treated with emicizumab. In particular, the CWA-TT in patients treated with FVIII concentrate showed that the peak heights were significantly higher in platelet-rich plasma than in platelet-poor plasma. In plasma with approximately 16% of FVIII activity based on APTT assay from patients treated with FVIII concentrate, the peak height on the CWA-sTF/FIXa showed a higher hemostatic abilitythan normal plasma. Conclusions: The CWA-TT can measure the FVIII activity in patients treated with emicizumab. Although routine APTT evaluations demonstrate a low hemostatic ability in patients treated with FVIII concentrate, the CWA-TT and CWA-sTF/FIXa show hypercoagulability in those patients.

Food and drinks can be contaminated with pollutants such as lead and strontium and this poses a serious danger to human health. For this reason, a number of effective sensors have been developed for the rapid and highly selective detection of such contaminants. TBA, a well-known aptamer developed to selectively target and thereby inhibit the protein of clinical interest -thrombin, is receiving increasing attention for sensing applications, particularly for the sensing of different cations. Indeed, TBA, in the presence of these cations, folds into the stable G-quadruplex structure. Furthermore, different cations produce small but significant changes in this structure that result in changes in the electrical responses that TBA can produce. In this article we produce an overview of the expected data regarding the use of TBA in the detection of lead and strontium, calculating the expected electrical response using different measurement techniques. Finally, we conclude that the TBA should perform better as a detector of strontium rather than lead.

It is currently unknown whether thrombin generation is associated with venous thromboembolism (VTE) recurrence, major bleeding, and mortality in the elderly. Therefore, our aim was to prospectively study the association between thrombin generation and VTE recurrence, major bleeding and mortality in elderly patients with acute VTE. Consecutive patients aged ≥65years with acute VTE were followed for 2 years starting from 1 year after the index VTE. Primary outcomes were VTE recurrence, major bleeding and mortality. Thrombin generation was assessed in 565 patients 1 year after the index VTE. At this time, 59% of patients were still anticoagulated. Thrombin generation was discriminatory for VTE recurrence, but not for major bleeding and mortality in non-anticoagulated patients. Moreover, peak ratio (adjusted subhazard ratio 4.09, 95% CI, 1.12-14.92) and normalized peak ratio (adjusted subhazard ratio 2.18, 95% CI, 1.28-3.73) in presence/absence of thrombomodulin were associated with VTE recurrence, but not with major bleeding and mortality after adjustment for potential confounding factors. In elderly patients, thrombin generation was associated with VTE recurrence, but not with major bleeding and/or mortality. Therefore, our study suggests the potential usefulness of thrombin generation measurement after anticoagulation completion for VTE to help identifying among elderly patients those at higher risk of VTE recurrence.

Hemorrhagic shock is the primary cause of death in patients with severe trauma, and the development of rapid and efficient hemostatic methods is of great significance in promoting the life-saving of trauma patients. In this study, polycaprolactone (PCL) nanofiber membrane was prepared by electrospinning technology. The PCL-PDA loading system was developed by modifying the surface of polydopamine (PDA) inspired by mussel adhesion protein, and the efficient and stable loading of thrombin (TB) was realized on the premise of ensuring the bioactivity of TB. The new thrombin loading system overcomes the disadvantages of harsh storage conditions, poor strength, easy to fall off, and can use thrombin to start rapid coagulation cascade reaction, which has the characteristics of fast hemostasis, good biocompatibility, high safety and wide range of hemostasis. The physicochemical properties and biocompatibility of PCL-PDA-TB membrane were verified by scanning electron microscopy, cell proliferation test, cell adhesion test and extract cytotoxicity test. Red blood cell adhesion, platelet adhesion, dynamic coagulation time and animal models all verified the coagulation effect of PCL-PD-TB membrane. Therefore, PCL-PDA-TB membrane has great potential in wound hemostasis.

Background: The patients with cancer, especially pancreas cancer, are frequently associated with thrombosis which is one of causes for poor outcome, and hypercoagulability exists in cancer patients. Hypercoagulability is considered to be caused by thrombin burst. Methods: Activated partial thromboplastin time (APTT), small amount of tissue factor induced FIX activation (sTF/FIXa) assays and thrombin time (TT) using clot waveform analysis (CWA) were performed in 138 patients with malignant neoplasm including pancreas cancer and 66 non-cancer patients. Results: Thrombosis was frequently associated in pancreas cancer and was observed in stage I. CWA-APTT showed that the peak times and heights were markedly long and heigh, respectively, in cancer patients, and the peak times were significantly longer in pancreas cancer patients than benign pancreas diseases, and the 1st DPH was significantly higher in pancreas cancers than other cancers or benign pancreas diseases. CWA-sTF/FIXa showed that the peak times and heights were longer and higher, respectively, in patients with cancer than those without cancers, and that the 1st DPH was significantly higher in pancreas cancers than in other cancers. CWA-TT showed that the peak times were significantly shorter in cancer patients than in healthy volunteers and that the peak heights were significantly higher in cancer than in benign pancreas diseases. Conclusions: Cancer patients including pancreas cancer were frequently associated with thrombosis due to hypercoagulability with thrombin burst detected by CWA.

The process of blood coagulation, wherein circulating blood transforms into a clot in response to internal or external injury, is a critical physiological mechanism. Monitoring this coagulation process is vital to ensure that blood clotting occurs neither too rapidly nor too slowly. Anticoagulants, a category of medications designed to prevent and treat blood clots, require meticulous monitoring to optimise dosage, enhance clinical outcomes, and minimise adverse effects. This review article delves into the various stages of blood coagulation, explores commonly used anticoagulants and their targets within the coagulation enzyme system, and emphasises the electrochemical methods employed in anticoagulant testing. Electrochemical sensors for anticoagulant monitoring are categorised into two types. The first type focuses on assays measuring thrombin activity via electrochemical techniques. The second type involves modified electrode surfaces that either directly measure the redox behaviour of anticoagulants or monitor the response of standard redox probes in the presence of these drugs. The review provides a comprehensive list of different electrode compositions and their detection and quantification limits. Additionally, it discusses the potential of employing a universal calibration plot to replace individual drug-specific calibrations. The insights presented are anticipated to significantly contribute to the sensor community's efforts in this field.

During the last two decades several cases of venous thrombosis (VTE) after a prolonged period at a computer has been described, denominated “eThrombosis”. Video gaming on a computer has become very popular and can be a social activity where several players are gathered to play against each other or in a virtual environment for several days (“LAN (i.e., Local Area Network) parties”) where the participants are sedentary and consuming calorie-rich food items. The aim of this study was to investigate a potential coagulation activation during a 42 hour LAN party. Nine male gamers volunteered for the LAN party. Citrated blood was sampled before and every 6 hours, and plasma was analyzed for thrombin generation, and Thrombin-antithrombin-complexes (TAT), prothrombin Fragment 1+2 (F1+2), and D-dimer. Thrombin generation increased slightly but not significantly during the LAN party, whereas the coagulation activation markers were unchanged. These results do not indicate that the coagulation system is activated significantly during 42 h gaming with minimal physical activity. Although an increased activity cannot be excluded, it does not directly indicate a risk of VTE in general. It may be specific and particularly susceptible in-dividuals who are prone to thrombosis and, therefore, are at risk of developing e-thrombosis.

COVID-19 thromboembolic disease has brought all of us back to the drawing board. In COVID-19, pre-existing activated endothelium with increased Von Willebrand factor (VWF), low density lipoprotein (LDL) promoting “self-association” and “sticking” of long VWF strings to the vascular endothelial wall, suppressed ADAMTS13 cleavage of VWF, hypoxia induced upregulation and activation of VWF, fibrous network from neutrophil extracellular traps (NETs) with free DNA and histone, all appear to be initiating the thrombogenesis. Worsening complement activation, cytokine storm and resulting endothelial destruction, unregulated thrombogenesis leads to vascular occlusions and hypoxia. At this stage, the presence of abundant extracellular DNA, histone and -defensins appears worse than the SARS-CoV-2 itself. Previously observed in vitro mechanisms like histone “auto-activating” prothrombin, histone activated platelets generating thrombin without FXII, thrombin and plasmin cleaving complement C5 appears highly likely in COVID-19. Megakaryocytes are actively producing platelets in the lungs and appear to play a major role in thrombogenesis of COVID-19 raising suspicion of emperipolesis. This focused review is a compilation of my observations in relation to the pathophysiology of the intravascular environment, mainly in COVID-19 lungs. Pathophysiology based clinical trials are paramount in reducing morbidity and mortality in COVID-19.

Thrombin (factor IIa) and factor Xa (FXa) are key enzymes at the junction of the intrinsic and extrinsic coagulation pathways and are the most attractive pharmacological targets for the development of novel anticoagulants. Twenty non-amidino N²-thiophencarbonyl- and N²-tosyl anthranilamides 1-20 and six amidino N²-thiophencarbonyl- and N²-tosylanthranilamides 21-26 were synthesized and evaluated prothrombin time (PT) and activated partial thromboplastin time (aPTT) using human plasma at concentration 30 μg/mL in vitro. From these results, compounds 5, 9, and 21-23 were selected to study the further antithrombotic activity. The anticoagulant properties of 5, 9, and 21-23 significantly exhibited a concentration-dependent prolongation of in vitro PT and aPTT, in vivo bleeding time, and ex vivo clotting time. These compounds concentration-dependently inhibited the activities of thrombin and FXa and inhibited the generation of thrombin and FXa in human endothelial cells. In addition, data showed that 5, 9, and 21-23 significantly inhibited thrombin catalyzed fibrin polymerization and mouse platelet aggregation and inhibited platelet aggregation induced U46619 in vitro and ex vivo. N-(3'-Amidinophenyl)-2-((thiophen-2''-yl)carbonyl amino)benzamide (21) was most active.

In this brief communication, we propose the concept that capillary regression may represent a primary pathogenic process underlying COVID-19 infection, particularly in the serious and life-threatening manifestations of the disease. We suggest that the marked elevations of pro-inflammatory mediators that are observed in these seriously ill patients may directly induce capillary regression and endothelial cell (EC) loss. Recent autopsy studies are demonstrating EC loss leading to widespread microthrombi and associated tissue damage. Recent work has indicated that interleukin-1 beta (IL-1β), tumor necrosis factor-alpha (TNFα), and thrombin, individually and in combination, can potently cause capillary tube regression in experimental models in vitro and in vivo. Other pro-inflammatory mediators including interferon gamma (IFNγ), interleukin-4 (IL-4), and interleukin-13 (IL-13) were also shown to be pro-regressive and could be relevant mediators in COVID-19 patients. Interestingly, combinations of pharmacologic agents were identified that reduced capillary regression and protected capillary tube networks against these pro-inflammatory mediators. Such an approach might be an important therapeutic option going forward to treat key disease states where capillary regression plays a major underlying pathogenic role. Finally, if capillary regression is occurring in response to these pro-inflammatory mediators during COVID-19 infection, we suggest that combinations of blocking agents directed to these key pro-regressive mediators might be necessary to appropriately treat patients.

Activated platelets are involved in blood coagulation by exposing phosphatidylserine (PS), which serves as a substrate for assembling coagulation complexes. Platelets accelerate fibrin formation and thrombin generation, two final reactions of the coagulation cascade. We investigated the effects of antiplatelet drugs on platelet impact in these reactions and platelet ability to expose PS. Washed human platelets were incubated with acetylsalicylic acid (ASA), ticagrelor, ASA in combination with ticagrelor, ruciromab (glycoprotein IIb-IIIa antagonist) or prostaglandin E1 (PGE1). Platelets were not activated or activated by collagen, sedimented in multiwell plates and plasma was added after supernatant removal. Fibrin formation (clotting) was monitored in a recalcification assay by light absorbance and thrombin generation in a fluorogenic test. PS exposure was assessed by annexin V staining using flow cytometry. Ticagrelor (alone and in combination with ASA), ruciromab and PGE1, but not ASA prolonged the lag phase and decreased the maximum rate of plasma clotting, and decreased the peak and maximum rate of thrombin generation. Inhibition was observed when platelets were not treated with exogenous agonists (activation by endogenous thrombin) and pretreated with collagen. Ticagrelor (alone and in combination with ASA), ruciromab and PGE1, but not ASA decreased PS exposure on washed platelets activated by thrombin and by thrombin + collagen. PS exposure on activated platelets in whole blood was lower in patients with acute coronary syndrome receiving ticagrelor + ASA in comparison with donors free of medications. These results indicate that antiplatelet drugs are able to suppress platelet coagulation activity not only in vitro but also after administration to patients.

Specific proteolytic cleavages turn on, modify, or turn off the activity of vascular endothelial growth factors (VEGFs). Proteolysis is most prominent among the lymph­angiogenic VEGF-C and VEGF-D, which are synthesized as precursors that need to undergo enzymatic removal of their C- and N-terminal propeptides before they can activate their receptors. The activating cleavage of VEGF-C is mediated by at least five different proteases: plasmin, ADAMTS3, prostate-specific antigen, cathepsin D, and thrombin. All of these proteases except for ADAMTS3 can also activate VEGF-D. Processing by different proteases results in distinct forms of the "mature" growth factors, which differ in affinity and receptor activation potential. The “default” VEGF-C-activating enzyme ADAMTS3 does not activate VEGF-D and therefore, VEGF-C and VEGF-D do function in different contexts. VEGF-C itself is also regulated in different contexts by different proteases. During embryonic development, ADAMTS3 activates VEGF-C. In contrast, thrombin and plasmin likely activate VEGF-C/-D during tissue injury-induced lymphangiogenesis, and PSA and cathepsin D perhaps during tumor-associated pathological lymphangio­genesis. Additionally, cathepsin D from saliva might activate latent VEGF-C/-D upon wound licking, thereby accelerating healing. Similar to tyrosine kinase receptors and VEGFs themselves, these activating proteases could be targeted to modulate angiogenesis and lymphangiogenesis in relevant diseases.