Clot Growth Research Articles

Prediction of Thrombus Formation within an Oxygenator via Bioimpedance Analysis.

Blood clot formation inside the membrane oxygenator (MO) remains a risk in extracorporeal membrane oxygenation (ECMO). It is associated with thromboembolic complications and normally detectable only at an advanced stage. Established clinical monitoring techniques lack predictive capabilities, emphasizing the need for refinement in MO monitoring towards an early warning system. In this study, an MO was modified by integrating four sensor fibers in the middle of the hollow fiber mat bundle, allowing for bioimpedance measurement within the MO. The modified MO was perfused with human blood in an in vitro test circuit until fulminant clot formation. The optical analysis of clot residues on the extracted hollow fibers showed a clot deposition area of 51.88% ± 14.25%. This was detectable via an increased bioimpedance signal with a significant increase 5 min in advance to fulminant clot formation inside the MO, which was monitored by the clinical gold standard (pressure difference across the MO (dp-MO)). This study demonstrates the feasibility of detecting clot growth early and effectively by measuring bioimpedance within an MO using integrated sensor fibers. Thus, bioimpedance may even outperform the clinical gold standard of dp-MO as a monitoring method by providing earlier clot detection.

Influence of the Immune Checkpoint Inhibitors on the Hemostatic Potential of Blood Plasma

Introduction: Immune checkpoint inhibitors (ICIs) have revolutionized classical treatment approaches of various cancer entities, but are also associated with a number of side effects. One of these may be life-threatening clotting disorders with the risk of thrombotic or hemorrhagic complications, the mechanisms of which are still poorly understood. In the present study, we analyzed the direct effects of pembrolizumab, nivolumab, and ipilimumab on platelet aggregation as well as plasma coagulation followed by fibrinolysis in an ex vivo model. Methods: Microplate spectrometry was used to analyze aggregation, coagulation, and fibrinolysis in platelet-free (PFP) and platelet-rich (PRP) healthy donor plasma samples treated with pembrolizumab, nivolumab, ipilimumab, and appropriate isotype controls. Aggregation was induced by TRAP-6. Clotting of PFP and PRP followed by lysis was initiated with a tissue factor in a mixture of phosphatidylserine:phosphatidylcholine and the addition of t-PA. Among other parameters, the area under the curve (AUC) was used to compare the effect of ICIs on aggregation, coagulation, and fibrinolysis. Results: Upon direct contact with platelets, pembrolizumab stimulated platelet aggregation in PRP, while nivolumab and ipilimumab promoted disaggregation with corresponding changes in the AUC. Pembrolizumab and nivolumab, both PD-1 receptor inhibitors, had no effect on the plasma coagulation cascade. Ipilimumab, a CTLA-4 receptor inhibitor, significantly increased the rate of PRP clotting. When clotting was followed by lysis, all ICIs were found to prolong the growth of the PRP-derived fibrin clot and delay its elimination. This was manifested by an increase in AUC relative to control PRP. Conclusion: This study characterizes the potential impact of pembrolizumab, nivolumab, and ipilimumab on hemostasis. Nivolumab and ipilimumab are able to reduce aggregation and increase the procoagulant properties of platelets, which can cause side effects associated with hemostatic imbalance leading to thrombosis or bleeding. The observed ICI-specific effects may contribute to our understanding of the mechanisms by which ICI affects platelets and suggest how, in a clinical setting, to reduce coagulation disorders during ICI treatment in the future.

Pro‑coagulant Considerations in Patients with Arterial Hypertension and Multifocal Atherosclerosis

The aim of the work to determine the features of hemostasis and blood rheology in patients with arterial hypertension (HTN) and multifocal atherosclerosis (MFA).Materials and methods. The study enrolled male and female patients aged from 40 to 70 years, including 59 patients with controlled stage I–II hypertension and multifocal vascular lesions (Group 1) and 42 patients with controlled stage III hypertension, who have suffered an ischemic stroke and have multifocal vascular lesions (Group 2). A test using the Thrombodynamics analyser system T-2 (GemaKor, LLC, Moscow, Russia) was performed to detect the impairment of hemostasis.Results. Patients with HTN and MFA have an impaired coagulation hemostasis system (an increase in the initial and stationary clot growth rate and the size of the clot, as well as the presence of spontaneous clots), which leads to a high residual risk of cerebral complications, despite BP lowering to target figures and control of lipid profile.Discussion. Elevated blood pressure in patients with MFA leads to endothelial dysfunction, which is accompanied by activation of coagulation and fibrinolysis pathways. These changes lead to a violation of microcirculatory hemostasis in the brain, the development and progression of cerebral ischemia, and subsequently the occurrence of stroke, both the first and repeated.Conclusion. An important result of this study is the first registered change in the coagulation link of hemostasis in patients with HTN and MFA aged from 40 to 70 years, which can be considered an additional criterion for stroke prediction.

Trauma patients have reduced ex vivo flow-dependent platelet hemostatic capacity in a microfluidic model of vessel injury.

Trauma is the leading cause of death in individuals up to 45 years of age. Alterations in platelet function are a critical component of trauma-induced coagulopathy (TIC), yet these changes and the potential resulting dysfunction is incompletely understood. The lack of clinical assays available to explore platelet function in this patient population has hindered detailed understanding of the role of platelets in TIC. The objective of this study was to assess trauma patient ex vivo flow-dependent platelet hemostatic capacity in a microfluidic model. We hypothesized that trauma patients would have flow-regime dependent alterations in platelet function. Blood was collected from trauma patients with level I activations (N = 34) within 60 min of hospital arrival, as well as healthy volunteer controls (N = 10). Samples were perfused through a microfluidic model of injury at venous and arterial shear rates, and a subset of experiments were performed after incubation with fluorescent anti-CD41 to quantify platelets. Complete blood counts were performed as well as plasma-based assays to quantify coagulation times, fibrinogen, and von Willebrand factor (VWF). Exploratory correlation analyses were employed to identify relationships with microfluidic hemostatic parameters. Trauma patients had increased microfluidic bleeding times compared to healthy controls. While trauma patient samples were able to deposit a substantial amount of clot in the model injury site, the platelet contribution to microfluidic hemostasis was attenuated. Trauma patients had largely normal hematology and plasma-based coagulation times, yet had elevated D-Dimer and VWF. Venous microfluidic bleeding time negatively correlated with VWF, D-Dimer, and mean platelet volume (MPV), while arterial microfluidic bleeding time positively correlated with oxygenation. Arterial clot growth rate negatively correlated with red cell count, and positively with mean corpuscular volume (MCV). We observed changes in clot composition in trauma patient samples reflected by significantly diminished platelet contribution, which resulted in reduced hemostatic function in a microfluidic model of vessel injury. We observed a reduction in platelet clot contribution under both venous and arterial flow ex vivo in trauma patient samples. While our population was heterogenous and had relatively mild injury severity, microfluidic hemostatic parameters correlated with different patient-specific data depending on the flow setting, indicating potentially differential mechanistic pathways contributing to platelet hemostatic capacity in the context of TIC. These data were generated with the goal of identifying key features of platelet dysfunction in bleeding trauma patients under conditions of flow and to determine if these features correlate with clinically available metrics, thus providing preliminary surrogate markers of physiological platelet dysfunction to be further studied across larger cohorts. Future studies will continue to explore those relationships and further define mechanisms of TIC and their relationship with patient outcomes.

Hemostasis parameters in patients with arterial hypertension, multifocal atherosclerosis and risk factors

Aim. To determine the features of hemostasis system disorders and the possibility of their correction in patients with arterial hypertension (AH) and multifocal atherosclerotic lesions (MFA) with risk factors indicated.Materials and methods. The study included 135 patients (mean age 53.7 ± 7.76 years), including 80 patients with controlled AH stage and II (group 1) and 55 patients with controlled AH stage III who had ischemic stroke (group 2). Among all patients studied, 33 patients (24.4 %) were smokers. All 135 patients received comparable antihypertensive, antiplatelettherapy (acetylsalicylic acid at a dose of 100 mg/day), had MFA and target lipid spectrum values.Results. Procoagulant shifts are noted already in patients with AH stage I and II, especially in the presence of smoking. Such indices of global thrombodynamics test as initial clot growth rate, average clot growth rate, clot size significantly exceed the reference values and indicate high prothrombogenic potential in patient with AH and MFA. Prescription of dual antiplatelet therapy allows normalization of identified disorders. Presence of risk factors (smoking) aggravates existing hemostasis disorders in patients with AH and MFA.Conclusion. Smoking cessation, optimization of risk factors and complex antihypertensive, hypolipidemic and antithrombotic therapy are the basis of treatment of patients with AH and MFA and can be considered as priority measures to reduce morbidity and mortality in this patient population.

Global coagulation assays detect an early prothrombotic state in children with acute lymphoblastic leukemia

BackgroundPediatric patients with acute lymphoblastic leukemia (ALL) are at highest risk of venous thromboembolism during the induction therapy (IT). These events are not predictable by conventional coagulation assays. ObjectivesTo investigate the utility of global coagulation assays (GCAs) for assessing the hemostatic state in children with ALL during IT. MethodsWe included children with ALL (n = 15) and healthy controls (n = 15). Analyses were performed at different time points during IT of the AIEOP-BFM protocols. In addition to prothrombotic biomarkers, natural anticoagulant proteins, and in vivo thrombin generation (TG) markers, ex vivo TG was measured using the gold standard calibrated automated thrombogram method, automated ST Genesia, and thrombodynamics analyzer (TD). The latter also provided measurement of fibrin clot formation. ResultsDifferent from conventional coagulation assays and in vivo TG markers, ex vivo GCAs detected increasing prothrombotic changes during IT. Particularly, TG measured with TD as expressed by endogenous thrombin potential was already significantly elevated at days 8 to 12 (P < .01) and continued to increase during IT compared with prior to beginning treatment, indicating a very early shift toward a procoagulant state. A similar pattern was observed for the rate of fibrin clot formation (stationary rate of clot growth: P < .01 at days 8-12). Remarkably, in patients developing thrombotic complications (n = 5), both GCAs, ST Genesia and TD, showed a significantly higher endogenous thrombin potential very early (already at days 8-12, P < .05), well before clinical manifestation. ConclusionGCAs capture prothrombotic changes early during IT in ALL pediatric patients. If confirmed, this approach will allow tailoring thromboprophylaxis in children with ALL at highest risk for venous thromboembolism.

Phosphate-Buffered Saline and Dimethyl Sulfoxide Enhance the Antivenom Action of Ruthenium Chloride against Crotalus atrox Venom in Human Plasma-A Preliminary Report.

Ruthenium chloride (RuCl3) is widely utilized for synthesis and catalysis of numerous compounds in academia and industry and is utilized as a key molecule in a variety of compounds with medical applications. Interestingly, RuCl3 has been demonstrated to modulate human plasmatic coagulation and serves as a constituent of a compounded inorganic antivenom that neutralizes the coagulopathic effects of snake venom in vitro and in vivo. Using thrombelastography, this investigation sought to determine if RuCl3 inhibition of the fibrinogenolytic effects of Crotalus atrox venom could be modulated by vehicle composition in human plasma. Venom was exposed to RuCl3 in 0.9% NaCl, phosphate-buffered saline (PBS), or 0.9% NaCl containing 1% dimethyl sulfoxide (DMSO). RuCl3 inhibited venom-mediated delay in the onset of thrombus formation, decreased clot growth velocity, and decreased clot strength. PBS and DMSO enhanced the effects of RuCl3. It is concluded that while a Ru-based cation is responsible for significant inhibition of venom activity, a combination of Ru-based ions containing phosphate and DMSO enhances RuCl3-mediated venom inhibition. Additional investigation is indicated to determine what specific Ru-containing molecules cause venom inhibition and what other combinations of inorganic/organic compounds may enhance the antivenom effects of RuCl3.

Long-term anticoagulant therapy in the aspect of secondary prevention of recurrent pulmonary embolism

Aim. To determine differences in laboratory coagulation parameters using routine and integral monitoring methods in patients depending on anticoagulant therapy &gt;12 months after pulmonary embolism (PE) with a high recurrence risk.Material and methods. The study included 72 patients who, according to indications, received long-term anticoagulant therapy &gt;12 months due to a high risk of recurrent thromboembolism. During the follow-up period (15-20 months from the first pulmonary embolism episode), the plasma coagulation parameters were studied using a conventional panel and D-dimer assessment, as well as a thrombin generation test and thrombodynamics. Patients adherent to prolonged anticoagulation were included in group 1. During the collection period, 8 patients independently stopped taking anticoagulants, despite the high risk of recurrent pulmonary embolism (group 2).Results. There were no significant differences in coagulation parameters and D-dimer levels between the studied groups of patients. In the group of patients continuing to take anticoagulants, there was an increase in clot growth delay parameters in comparison with patients of group 2 according to the thrombodynamics results (p=0,046) and the thrombin generation test in platelet-poor plasma in comparison with reference values (p=0,001).Conclusion. Long-term anticoagulant therapy effectively prevents recurrent venous thromboembolism. In patients after primary pulmonary embolism who refuse anticoagulation, the clot growth delay values are shortened, which indicates an increased risk of recurrent venous thromboembolism. The most stable plasma coagulation parameters are observed in patients taking direct oral anticoagulants.

Comparison of thrombodynamic tests with determination of anti-Xa activity in evaluation of the efficacy of anticoagulant therapy in patients suffering deep vein thrombosis of the lower extremities

Deep vein thrombosis of the lower extremities remains an important medical and social problem in practical medicine. Currently, a weight-dependent low-molecular-weight heparin dosing approach is used to treat deep vein thrombosis of the lower extremities in wounded patients without regard to the state of the hemostasis system. This observational study included 30 patients with deep vein thrombosis of the lower extremities who were hospitalized for examination and treatment at the Kirov Military Medical Academy. During treatment with enoxaparin sodium at therapeutic doses, depending on body weight, the parameters of the thrombodynamics test were assessed in all patients, and antiXa activity was determined at the peak of the drug (after 3–4 h) and at the end (before the next injection) of its action. A strong inverse correlation was established between the growth rate indicator of the thrombodynamics test clot and antiXa activity at the peak (–0.777; p 0.05) and at the end (–0.715; p 0.05) of the action of sodium enoxaparin. The standard dose of anticoagulant drug, depending on body weight, revealed that 30% of patients were in the hypercoagulation zone, not reaching the target values of the thrombodynamic clot growth rate and anti-Xa activity. The thrombodynamics test results identified the growth rate of the test clot with antiXa activity, which allows both methods to be considered comparable for laboratory monitoring low-molecular-weight heparin therapy in wounded individuals. The insufficient anticoagulant effect in one-third of the injured individuals that received the standard and therapeutic doses of low-molecular-weight heparins requires the development of a personalized approach to titration of low-molecular-weight heparins, which may be based not on the concentration of the drug per body weight but on the achieved anticoagulant effect that optimizes the treatment outcomes and patient prognosis. Accordingly, further research is required.

Ruthenium-based antivenom attenuates Crotalus atrox venom mediated coagulopathy in rabbits.

The Western diamondback rattlesnake ( Crotalus atrox ) is a medically important venomous snake in the Southwestern United States, injuring humans, and their companion animals. The goals of this investigation were to utilize a rabbit model of subcutaneous envenomation to assess Crotalus atrox venom coagulopathy and determine the efficacy of a ruthenium-containing antivenom (RA) in attenuating it. Sedated New Zealand White rabbits had viscoelastic measurements of whole blood coagulation kinetics obtained from ear artery samples. Crotalus atrox venom (4 mg/kg) was injected subcutaneously and changes in coagulation determined over three hours and compared to samples obtained prior to envenomation. Other rabbits had site-directed RA injected 5 min after venom injection. A significant decrease in the velocity of clot growth and thrombus strength was observed in animals injected with venom alone. Site-directed administration of RA resulted in no change in coagulation over the 3 h following venom injection. The interaction of antivenom administration and time was significantly different in the cases of clot growth velocity and strength. A novel rabbit model was used to define the toxicodynamic profile of coagulopathy of Crotalus atrox venom and demonstrate the efficacy of RA. Future investigation is planned involving other medically important venoms and RA administration.

Influence of vortical structures on fibrin clot formation in cerebral aneurysms: A two-dimensional computational study

Thrombosis is an important contributor to cerebral aneurysm growth and progression. A number of sophisticated multiscale and multiphase in silico models have been developed with a view towards interventional planning. Many of these models are able to account for clotting outcomes, but do not provide detailed insight into the role of flow during clot development. In this study, we present idealised, two-dimensional in silico cerebral fibrin clot model based on computational fluid dynamics (CFD), biochemical modelling and variable porosity, permeability, and diffusivity. The model captures fibrin clot growth in cerebral aneurysms over a period at least 1000 s in five different geometries. The fibrin clot growth results were compared to an experiment presented in literature. The biochemistry was found to be more sensitive to mesh size compared to the haemodynamics, while larger timesteps overpredicted clot size in pulsatile flow. When variable diffusivity was used, the predicted clot size was 25.4% lesser than that with constant diffusivity. The predicted clot size in pulsatile flow was 14.6% greater than in plug flow. Different vortex modes were observed in plug and pulsatile flow; the latter presented smaller intermediate modes where the main vortex was smaller and less likely to disrupt the growing fibrin clot. Furthermore, smaller vortex modes were seen to support fibrin clot propagation across geometries. The model clearly demonstrates how the growing fibrin clot alters vortical structures within the aneurysm sac and how this changing flow, in turn, shapes the growing fibrin clot.

GWAS-significant loci and severe COVID-19: analysis of associations, link with thromboinflammation syndrome, gene-gene, and gene-environmental interactions.

The aim of this study was to replicate associations of GWAS-significant loci with severe COVID-19 in the population of Central Russia, to investigate associations of the SNPs with thromboinflammation parameters, to analyze gene-gene and gene-environmental interactions. DNA samples from 798 unrelated Caucasian subjects from Central Russia (199 hospitalized COVID-19 patients and 599 controls with a mild or asymptomatic course of COVID-19) were genotyped using probe-based polymerase chain reaction for 10 GWAS-significant SNPs: rs143334143 CCHCR1, rs111837807 CCHCR1, rs17078346 SLC6A20-LLZTFL1, rs17713054 SLC6A20-LLZTFL1, rs7949972 ELF5, rs61882275 ELF5, rs12585036 ATP11A, rs67579710 THBS3, THBS3-AS1, rs12610495 DPP9, rs9636867 IFNAR2. SNP rs17713054 SLC6A20-LZTFL1 was associated with increased risk of severe COVID-19 in the entire group (risk allele A, OR = 1.78, 95% CI = 1.22-2.6, p = 0.003), obese individuals (OR = 2.31, 95% CI = 1.52-3.5, p = 0.0002, (p bonf = 0.0004)), patients with low fruit and vegetable intake (OR = 1.72, 95% CI = 1.15-2.58, p = 0.01, (p bonf = 0.02)), low physical activity (OR = 1.93, 95% CI = 1.26-2.94, p = 0.0035, (p bonf = 0.007)), and nonsmokers (OR = 1.65, 95% CI = 1.11-2.46, p = 0.02). This SNP correlated with increased BMI (p = 0.006) and worsened thrombodynamic parameters (maximum optical density of the formed clot, D (p = 0.02), delayed appearance of spontaneous clots, Tsp (p = 0.02), clot size 30min after coagulation activation, CS (p = 0.036)). SNP rs17078346 SLC6A20-LZTFL1 was linked with increased BMI (p = 0.01) and severe COVID-19 in obese individuals (risk allele C, OR = 1.72, 95% CI = 1.15-2.58, p = 0.01, (p bonf = 0.02)). SNP rs12610495 DPP9 was associated with increased BMI (p = 0.01), severe COVID-19 in obese patients (risk allele G, OR = 1.48, 95% CI = 1.09-2.01, p = 0.01, (p bonf = 0.02)), and worsened thrombodynamic parameters (time to the start of clot growth, Tlag (p = 0.01)). For rs7949972 ELF5, a protective effect against severe COVID-19 was observed in non-obese patients (effect allele T, OR = 0.67, 95% CI = 0.47-0.95, p = 0.02, (p bonf = 0.04)), improving thrombodynamic parameters (CS (p = 0.02), stationary spatial clot growth rates, Vst (p = 0.02)). Finally, rs12585036 ATP11A exhibited a protective effect against severe COVID-19 in males (protective allele A, OR = 0.51, 95% CI = 0.32-0.83, p = 0.004). SNPs rs67579710 THBS3, THBS3-AS1, rs17713054 SLC6A20-LZTFL1, rs7949972 ELF5, rs9636867 IFNAR2-were involved in two or more of the most significant G×G interactions (p perm ≤ 0.01). The pairwise combination rs67579710 THBS3, THBS3-AS1 × rs17713054 SLC6A20-LZTFL1 was a priority in determining susceptibility to severe COVID-19 (it was included in four of the top five most significant SNP-SNP interaction models). Overall, this study represents a comprehensive molecular-genetic and bioinformatics analysis of the involvement of GWAS-significant loci in the molecular mechanisms of severe COVID-19, gene-gene and gene-environmental interactions, and provides evidence of their relationship with thromboinflammation parameters in patients hospitalized in intensive care units.

Thrombodynamics and Quantitative phase imaging of platelets in the assessment of hemostasis in pregnant women with protein C / protein S deficiency

Relevance. A hypercoagulable state caused by hereditary or acquired deficiency of antithrombotic factors can contribute to disruption of the uteroplacental circulation with the development of serious pregnancy complications, which requires effective monitoring of hemostasis during the use of pathogenetic anticoagulant therapy.The purpose of the study is to improve methods for diagnosing and monitoring hemostatic disorders in pregnant women with thrombophilia (protein C/protein S deficiency) and complicated pregnancy based on the use of an integral thrombodynamic test and quantitative phase imaging of platelets.Material and methods. 45 pregnant women were examined in the first and second trimester: 20 women with normal pregnancy (comparison group) and 25 (main group) with thrombophilia (protein S/protein C deficiency). 16 pregnant women (subgroup 1A) received a full course of preconception preparation with the prescription of LMWH, 9 pregnant women (subgroup 1B) did not complete the course in full for various reasons. To study hemostasis, along with routine methods (determination of APTT, TT, PT, Fibrinogen, INR and D-dimer), an integral assessment of coagulation using the Thrombodynamics method and quantitative phase imaging (QPI) of platelets in real time were performed.Results. It was found that routine methods are not sufficiently informative; statistically significant changes against the background of thrombophilia and during treatment with LMWH were noted only based on the results of assessing the level of fibrinogen and D-dimer. In the complex of thrombodynamics indicators, the most sensitive parameters were the steady-state clot growth rate (Vst), clot size at 30 minutes of the study (CS) and clot density (D). The QPI method revealed features of the morphological structure of platelets with a predominance in pregnant women with protein S/protein C deficiency of the activated cell population with an increase in the median values of diameter and perimeter by 14 and 20 %, respectively (p &lt; 0.05). The effectiveness of LMWH therapy was assessed by normalization of the analyzed parameters.Conclusion. Timely and adequate correction of hemostasis disorders, carried out while monitoring coagulation and platelet parameters, taking into account all clinical data, can significantly reduce the risk of complications for the mother and fetus.

Platelets provide robustness of spatial blood coagulation to the variation of initial conditions

Activated platelets provide phospholipid surface and secrete coagulation factors, enhancing blood clotting. We investigated the role of platelets in the regulation of blood coagulation spatial dynamics. We activated blood clotting with tissue factor-bearing (TF) surface in platelet-rich plasma (PRP) or platelet-free plasma (PFP). When blood coagulation was initiated by high TF density, clot growth rate (V) in PRP (2 × 105/μL platelets) was only 15 % greater than in PFP. Spatial distribution of thrombin in PRP had a peak-like shape in the area of the fibrin clot edge, while in PFP thrombin was distributed in the shape of descending plateau. Platelet inhibition with prostaglandin E1 or cytochalasin D made spatial thrombin distribution look like in the case of PFP. Inhibition of blood coagulation by natural endogenous inhibitor heparin was diminished in PRP, while the effect of the exogenous or artificial inhibitors (rivaroxaban, nitrophorin, hirudin) remained undisturbed in the presence of platelets. Ten times decrease of the TF surface density greatly depressed blood coagulation in PFP. In PRP only clotting initiation phase was, while the propagation phase remained intact. Coagulation factor deficiency greatly reduced amount of thrombin and decreased V in PFP rather than in PPR. Thus, platelets were redundant for clotting in normal plasma under physiological conditions but provided robustness of the coagulation system to the changes in initial conditions.

Thrombin Generation Thresholds for Coagulation Initiation under Flow

In veins, clotting initiation displays a threshold response to flow intensity and injury size. Mathematical models can provide insights into the conditions leading to clot growth initiation under flow for specific subjects. However, it is hard to determine the thrombin generation curves that favor coagulation initiation in a fast manner, especially when considering a wide range of conditions related to flow and injury size. In this work, we propose to address this challenge by using a neural network model trained with the numerical simulations of a validated 2D model for clot formation. Our surrogate model approximates the results of the 2D simulations, reaching an accuracy of 94% on the test dataset. We used the trained artificial neural network to determine the threshold for thrombin generation parameters that alter the coagulation initiation response under varying flow speed and injury size conditions. Our model predictions show that increased levels of the endogenous thrombin potential (ETP) and peak thrombin concentration increase the likelihood of coagulation initiation, while an elevated time to peak decreases coagulation. The lag time has a small effect on coagulation initiation, especially when the injury size is small. Our surrogate model can be considered as a proof-of-concept of a tool that can be deployed to estimate the risk of bleeding in specific patients based on their Thrombin Generation Assay results.

СРАВНИТЕЛЬНЫЙ МОНИТОРИНГ АНТИКОАГУЛЯНТНОЙ ТЕРАПИИ У РАНЕНЫХ С ТРОМБОЗАМИ ГЛУБОКИХ ВЕН НИЖНИХ КОНЕЧНОСТЕЙ

Introduction. Deep vein thrombosis of the lower extremities (DVT) currently remains one of the most important problems affecting not only vascular surgeons, but also doctors of other specialties. Target. Carry out a comparative monitoring of methods for monitoring the effectiveness of anticoagulant therapy in the wounded using the Thrombodynamics test and determining anti-Xa activity. Materials and methods. The study included 30 wounded individuals with established DVT, hospitalized for examination and treatment at the Military Medical Academy. CM. Kirov. Against the background of treatment with enoxaparin sodium (hereinafter referred to as enoxaparin) at therapeutic doses, depending on body weight, all patients were assessed the parameters of the "Thrombodynamics" (TD) test and the determination of anti-Xa activity at the peak of the drug's action (after 3-4 hours), and on outcome (before the next injection) of the drug. Statistical data processing was carried out using the Statistica 10.0 application package. Results and discussion. A strong inverse correlation was established between the clot growth rate (V) of the TD test and the determination of anti-Xa activity at the peak (-0.777; p&lt;0.05) and at the end (-0.715; p&lt;0.05) of anticoagulant therapy. With the standard prescription of doses of anticoagulant therapy depending on body weight, it was found that 30% of patients did not reach the target values of the V TD test and anti-Xa activity and were in the hypercoagulable zone. Conclusion. The indicator of clot growth rate of the "Thrombodynamics" test correlates with the level of anti-Xa activity and can be used as another tool for laboratory monitoring of ongoing therapy with low molecular weight heparins (LMWH) in the wounded. The standard use of LMWH in therapeutic doses by body weight in the wounded does not always lead to the achievement of target coagulation parameters, which requires the development of a personalized approach to LMWH titration, which can be based on the indicators of TD tests and anti-Xa activity.

Fbg αC 389-402 Enhances Factor XIII Cross-Linking in the Fibrinogen αC Region Via Electrostatic and Hydrophobic Interactions.

Coagulation Factor XIII (FXIII) stabilizes blood clots by cross-linking glutamines and lysines in fibrin and other proteins. FXIII activity in the fibrinogen αC region (Fbg αC 221-610) is critical for clot stability and growth. Fbg αC 389-402 is a binding site for thrombin-activated FXIII, (FXIII-A*), with αC E396 promoting FXIII-A* binding and activity in αC. The current study aimed to discover additional residues within Fbg αC 389-402 that accelerate transglutaminase activity toward αC. Electrostatic αC residues (E395, E396, and D390), hydrophobic αC residues (W391 and F394), and residues αC 328-425 were studied by mutations to recombinant Fbg αC 233-425. FXIII activity was monitored through MS-based glycine ethyl ester (GEE) cross-linking and gel-based fluorescence monodansylcadaverine (MDC) cross-linking assays. Truncation mutations 403 Stop (Fbg αC 233-402), 389 Stop (Fbg αC 233-388), and 328 Stop (Fbg αC 233-327) reduced Q237-GEE and MDC cross-linking compared to wild-type (WT). Comparable cross-linking between 389 Stop and 328 Stop showed that FXIII is mainly affected by the loss of Fbg αC 389-402. Substitution mutations E396A, D390A, W391A, and F394A decreased cross-linking relative to WT, whereas E395A, E395S, E395K, and E396D had no effect. Similar FXIII-A* activities were observed for double mutants (D390A, E396A) and (W391A, E396A), relative to D390A and W391A, respectively. In contrast, cross-linking was reduced in (F394A, E396A), relative to F394A. In conclusion, Fbg αC 389-402 boosts FXIII activity in Fbg αC, with D390, W391, and F394 identified as key contributors in enhancing αC cross-linking.

Hemostasis assessment in Fontan patients using the new thrombodynamics test

BackgroundThromboembolic events are a well-known risk for Fontan patients and often lead to morbidity and mortality in cyanotic patients and patients with a single ventricle. Coagulopathy and thrombophilia, in addition to disturbed Fontan blood flow and endothelial injury, are major contributors to thromboembolic complications. However, there is currently no consensus regarding the optimal medication to prevent or treat these events. Identification of coagulation disorders is therefore crucial for selecting appropriate management strategies and evaluating long-term outcomes in these patients.Case presentationWe present the case of a 35-year-old male who underwent the Fontan procedure with a total cavopulmonary modification during childhood due to tricuspid atresia. He was admitted with complaints of headaches and visual disturbances, but no clear cardiovascular cause was identified. Standard coagulation test parameters were normal, but the thrombodynamics test indicated severe hypercoagulation and spontaneous clot formation. Anticoagulation therapy was initiated, and a subsequent thrombodynamics assay showed normalization of the coagulation parameters. The patient remained asymptomatic during the six-month follow-up period.ConclusionsThe thrombodynamics test is a valuable tool for the diagnosis of coagulation disorders, as it can assess coagulation parameters and clot growth in vitro. This method can also aid in the optimization of antithrombotic therapy. The presented clinical case highlights the potential use of the thrombodynamics test in Fontan patients to diagnose coagulation disorders and improve long-term outcomes.

Expert Consensus on the Use of Human Serum Albumin in Adult Cardiac Surgery.

Expert Consensus on the Use of Human Serum Albumin in Adult Cardiac Surgery.

Targeted Blood Plasma Proteomics and Hemostasis Assessment of Post COVID-19 Patients with Acute Myocardial Infarction

The molecular mechanisms underlying cardiovascular complications after the SARS-CoV-2 infection remain unknown. The goal of our study was to analyze the features of blood coagulation, platelet aggregation, and plasma proteomics in COVID-19 convalescents with AMI. The study included 66 AMI patients and 58 healthy volunteers. The groups were divided according to the anti-N IgG levels (AMI post-COVID (n = 44), AMI control (n = 22), control post-COVID (n = 31), and control (n = 27)). All participants underwent rotational thromboelastometry, thrombodynamics, impedance aggregometry, and blood plasma proteomics analysis. Both AMI groups of patients demonstrated higher values of clot growth rates, thrombus size and density, as well as the elevated levels of components of the complement system, proteins modifying the state of endothelium, acute-phase and procoagulant proteins. In comparison with AMI control, AMI post-COVID patients demonstrated decreased levels of proteins connected to inflammation and hemostasis (lipopolysaccharide-binding protein, C4b-binding protein alpha-chain, plasma protease C1 inhibitor, fibrinogen beta-chain, vitamin K-dependent protein S), and altered correlations between inflammation and fibrinolysis. A new finding is that AMI post-COVID patients opposite the AMI control group, are characterized by a less noticeable growth of acute-phase proteins and hemostatic markers that could be explained by prolonged immune system alteration after COVID-19.