Fibrin Formation Research Articles

Morphologic, Hemostasiologic and Hemostatic Aspects of Systemic Application of Exogenous Fibrin Monomer in Model of Posttraumatic Bleeding with Underlying Intake of Warfarin

INTRODUCTION: Earlier, an ability of exogenous fibrin monomer (FM) introduced at low doses to considerably limit posttraumatic blood loss was established by us on an experimental model of warfarin coagulopathy in vivo. However, the morphologic peculiarities of fibrin formation in the wound area were not considered.
 AIM: To compare morphologic, hemostasiologic and hemostatic data based on the results of systemic application of exogenous FM to interpret their effects in the model of posttraumatic bleeding with the underlying intake of warfarin.
 MATERIALS AND METHODS: In the work, Chinchilla male rabbits were used. A comparative analysis of hemostasiologic effects and of morphologic picture of the surface of the liver in the wound area was conducted after a dosed trauma, with a preliminary systemic introduction of FM (0.25 mg/kg intravenously) or a concentrate of prothrombin complex factors (40 IU/kg intravenously) with the underlying intake of warfarin by animals (0.40.5 mg/kg/day per os for 2 weeks).
 RESULTS: Introduction of FM in warfarinised animals in the conditions of a dosed experimental liver injury promoted a hemostatic effect comparable with that of a concentrate of prothrombin complex factors. Both hemostatic drugs led to intense fibrin formation that reduced posttraumatic blood loss. The use of FM was associated with increase in the thickness of thrombotic deposits and fibrin fibers in the wound surface in comparison with placebo by 4.0 and 1.6 times, respectively (р 0.000001). This process actively involved platelets, which led to 1.7 times reduction of their quantity in the lumen of the blood vessels in the wound vicinity (р 0.0002). No effect of FM on systemic hemostatic reactions in venous blood was found, in contrast to concentrate of prothrombin complex factors.
 CONCLUSION: Exogenous FM can produce a local hemostatic effect in the conditions of dosed experimental trauma and coagulopathy induced by warfarin intake. The hemostatic effect was mediated by intense thrombosis on the wound surface with the active recruitment of platelets in the process. The peculiarities of the demonstrated effects of FM may be mediated though the mechanisms of its action that have not yet been identified, which necessitates continuation of the research in this direction.

Transient particle tracking microrheology of plasma coagulation via the intrinsic pathway

Abstract The maintenance of hemostasis to ensure vascular integrity is dependent upon the rapid conversion of zymogen species of the coagulation cascade to their enzymatically active forms. This process culminates in the generation of the serine protease thrombin and polymerization of fibrin to prevent vascular leak at sites of endothelial cell injury or loss of cellular junctions. Thrombin generation can be initiated by the extrinsic pathway of coagulation through exposure of blood to tissue factor at sites of vascular damage, or alternatively by the coagulation factor (F) XII activated by foreign surfaces with negative charges, such as glass, through the contact activation pathway. Here, we used transient particle tracking microrheology to investigate the mechanical properties of fibrin in response to thrombin generation downstream of both coagulation pathways. We found that the structural heterogeneity of fibrin formation was dependent on the reaction kinetics of thrombin generation. Pharmacological inhibition of FXII activity prolonged the time to form fibrin and increased the degree of heterogeneity of fibrin, resulting in fibrin clots with reduced mechanical properties. Taken together, this study demonstrates a dependency of the physical biology of fibrin formation on activation of the contact pathway of coagulation.

Novel Movable Typing for Personalized Vein‐Chips in Large Scale: Recapitulate Patient‐Specific Virchow's Triad and its Contribution to Cerebral Venous Sinus Thrombosis

AbstractThe Vein‐Chip recapitulates CVST Virchow's triad and enables systematic characterization of venous thrombogenesis with respect to fibrin formation and platelet aggregation. Distinct from the arterial setting, platelets universally adhere across the entire CVS Vein‐Chip independent of stenotic geometry and flow disturbance. Intriguingly, fibrin propagates along with the flow direction, but exclusively deposits to the inner vessel wall. Upon inflammatory endothelial injury, fibrin deposition mirrors to the outer vessel wall, but still not in the lumen. Together, the Vein‐Chip promises future applications for personalized thrombotic assessment and monitoring.

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.

Late-onset toxic anterior segment syndrome after ICL implantation: two case reports

BackgroundToxic anterior segment syndrome (TASS) is a non-infectious inflammation that can occur after any anterior segment procedure. This case report presents two relatively rare late-onset TASS cases after V4c implantable collamer lens (ICL) operation.Case presentationOne 25-year-old woman and one 31-year-old woman suddenly had vision loss in monocular for 1 week after biocular V4c ICL operations and with no subjective complaints. They both presented fibrin formation in the anterior chamber such as keratic precipitates and white pus on the surface of the ICL. Fundus examination was normal. After 4 to 5 weeks of topical and oral steroid treatment, visual acuity and fibrin formation in the anterior chamber improved during the follow-up.ConclusionsTASS should be suspected in any patient during the late period following ICL surgery; Once TASS is diagnosed, adequate treatment with intensive steroid therapy can be implemented.

Inter-α-inhibitor heavy chain H4 and sepsis-related coagulation disturbances: Another link between innate immunity and coagulation

BackgroundThe protease inhibitor inter-α-inhibitor heavy chain H4 (ITIH4) has been described as an acute-phase reactant and could potentially aid in sepsis monitoring and prognostication. ObjectivesTo investigate ITIH4 plasma levels in sepsis patients compared with healthy controls and to examine the association between ITIH4 and acute-phase response markers, blood coagulation, and organ dysfunction in sepsis. MethodsWe performed a post hoc study to a prospective cohort study. Patients with septic shock (n = 39) were enrolled upon intensive care unit admission. ITIH4 was analyzed using an in-house immunoassay. Standard coagulation parameters, thrombin generation, fibrin formation and lysis, C-reactive protein, organ dysfunction markers, Sequential Organ Failure Assessment score, and disseminated intravascular coagulation (DIC) score were registered. ITIH4 levels were also investigated in a murine Escherichia coli sepsis model. ResultsITIH4 did not display acute-phase behavior as mean ITIH4 levels were not increased in patients with septic shock or in E. coli-infected mice. However, ITIH4 exhibited large interindividual variation in patients with septic shock compared with healthy controls. Low ITIH4 was associated with sepsis-related coagulopathy, including a high DIC score (mean ITIH4: DIC, 203 μg/mL vs non-DIC, 267 μg/mL, P = .01), low antithrombin (r = 0.70, P < .0001) and decreased thrombin generation (mean ITIH4: first peak thrombin tertile, 210 μg/mL vs third peak thrombin tertile, 303 μg/mL, P = .01). ITIH4 showed moderate correlation with arterial blood lactate (ρ = -0.50, P < .001) but only weak correlations with C-reactive protein, alanine transaminase, bilirubin, and Sequential Organ Failure Assessment score (all, ρ < 0.26, P > .05). ConclusionITIH4 is associated with sepsis-related coagulopathy but is not an acute-phase reactant during septic shock.

Sepsis-induced coagulopathy in preterm neonates with Gram-positive sepsis presents with hypercoagulation and reduced platelet activation compared with healthy preterm neonates

BackgroundNeonatal sepsis is frequently accompanied by coagulopathy and thrombocytopenia attributed to the cross-link between inflammation and coagulation. However, sepsis-induced coagulopathy and platelet function in septic preterm neonates remain to be elucidated. In addition, there is no robust evidence for a causal relationship between thrombocytopenia and bleeding in preterm neonates with sepsis. ObjectiveThis single-center prospective cohort study aimed to assess sepsis-induced coagulopathy and platelet function in preterm neonates during sepsis. MethodsWe included 25 preterm neonates with Gram-positive sepsis born at gestational age 24 + 1 to 34 + 3 and studied in comparison to 30 healthy counterparts. Coagulation was assessed using conventional coagulation tests (CCTs) and rotational thromboelastometry (ROTEM). Platelet function was evaluated by flow cytometry. The study was conducted at 3-time points, at 1st, at 2nd to 3rd, and at 5th to 7th day of sepsis, respectively. ResultsCompared with healthy controls, neonates with Gram-positive sepsis present in ROTEM a hypercoagulable state; a higher maximum clot firmness (MCF) and higher amplitudes of intrinsic rotational thromboelastometry (INTEM) (INTEM MCF: median, 71; P .004 and INTEM A10: median, 67; P .005, respectively), extrinsic rotational thromboelastometry (EXTEM) (EXTEM MCF: median, 70; P .02 and EXTEM A10: median, 67; P .02, respectively), and rotational thromboelastometry assay for fibrin formation (FIBTEM) (FIBTEM MCF: median, 25; P < .001 and FIBTEM A10: median, 23; P .002, respectively). Conversely, CCTs exhibited hypocoagulation. Thrombocytopenia in preterm neonates with Gram-positive sepsis is not associated with an increased bleeding risk. In Gram-positive sepsis, platelets display increased glycoprotein (GP) surface receptors' expression (GPIb: median, 2.8; P .03, GPIIb: median, 3.1; P .004, and GPIIIa: median, 3.9; P .008, respectively) and reduced activation (P-selectin: median, 1; P < .001). A higher expression of platelets GP and improved degranulation capacity were recorded in patients in higher gestational age groups of >32 weeks of gestation. Platelet GPIb expression is age-dependent in healthy neonates. ConclusionNeonatal Gram-positive sepsis is characterized by a progressive hypercoagulation along with increased GP expression, reduced platelet activation, and thrombocytopenia without bleeding. Platelet GP expression and degranulation capacity are age-dependent among neonates with sepsis. Platelet GP expression is age-dependent among healthy counterparts.

Piericones A and B as Potent Antithrombotics: Nanomolar Noncompetitive Protein Disulfide Isomerase Inhibitors with an Unexpected Chemical Architecture

Extracellular protein disulfide isomerase (PDI) is a promising target for thrombotic-related diseases. Four potent PDI inhibitors with unprecedented chemical architectures, piericones A-D (1-4), were isolated from Pieris japonica. Their structures were elucidated by spectroscopic data analysis, chemical methods, quantum 13C nuclear magnetic resonance DP4+ and electronic circular dichroism calculations, and single-crystal X-ray diffraction analysis. Piericones A (1) and B (2) were nanomolar noncompetitive PDI inhibitors possessing an unprecedented 3,6,10,15-tetraoxatetracyclo[7.6.0.04,9.01,12]pentadecane motif with nine contiguous stereogenic centers. Their biosynthetic pathways were proposed to include a key intermolecular aldol reaction and an intramolecular 1,2-migration reaction. Piericone A (1) significantly inhibited in vitro platelet aggregation and fibrin formation and in vivo thrombus formation via the inhibition of extracellular PDI without increasing the bleeding risk. The molecular docking and dynamics simulation of 1 and 2 provided a novel structure basis to develop PDI inhibitors as potent antithrombotics.

DOAC-stop can remove direct oral anticoagulants and allow analysis by global coagulation assays.

Activated charcoal based compounds such as DOAC-stop™ (DS) have been developed to remove direct oral anticoagulant (DOAC) interference in-vitro. However, few studies have used this approach with global coagulation assays (GCAs), such as thrombin generation assays, which are sensitive to the effect of DOACs. Thrombin generation with and without thrombomodulin (TM) via the automated ST-Genesia system, and the overall haemostatic potential (OHP) assay, a spectrophotometric fibrin generation assay in which fibrin formation (triggered by small amounts of thrombin (overall coagulation potential, OCP)) and fibrinolysis (by the addition of thrombin and tissue plasminogen activator) were measured on (i) pooled normal plasma (PNP) spiked with varying amounts of rivaroxaban, apixaban, and dabigatran, and (ii) platelet poor plasma (PPP) from 21 non-anticoagulated adults, before and after DS addition. Following the addition of DS to spiked PNP without thrombomodulin, thrombin and velocity index increased by 21.9% and 42.6%, respectively, while ETP increased by 6.93%. A decrease in OCP (-10.6%) and OHP (-12.7%) was observed following DS. Similar changes were seen post-DS to plasma from non-anticoagulated patients. Also in this group, pre- and post-DS thrombin generation parameters showed high correlation, with the strongest observed for ETP (R2 = 0.94). There was a strong correlation for OHP parameters, with the closest seen with OCP (R2 = 0.96) and OHP (R2 = 0.95). DS causes some changes to the ETP and OHP assay, however, strong correlations were seen pre- and post-DS in all GCA parameters. These findings support the use of DS to facilitate GCA testing in anticoagulated individuals for evaluation of the underlying thrombotic state.

Sex-dependent effects of canagliflozin and dapagliflozin on hemostasis in normoglycemic and hyperglycemic mice

Sodium-glucose cotransporter 2 inhibitors (SGLT2i) are antihyperglycemic drugs that decrease mortality from cardiovascular diseases. However, their effects on hemostasis in the cardioprotective effects have not been evaluated. Therefore, the effects of canagliflozin (CANA, 100 mg/kg, p.o.) and dapagliflozin (DAPA, 10 mg/kg, p.o.) on the parameters of hemostasis were investigated in female and male normoglycemic and streptozotocin (180 mg/kg, i.p.)-induced diabetic mice. CANA and DAPA reduced platelet activity in thrombus in male and female mice both normoglycemic and diabetic. CANA decreased thrombus formation in diabetic male mice, and platelet activation to ADP in diabetic female and male mice. Activation of fibrinolysis was observed in female mice, both normoglycemic and diabetic. DAPA reduced thrombus formation in diabetic male and female mice, and decreased platelet activation to ADP and fibrin formation in diabetic male mice. DAPA increased fibrin formation in normoglycemic female mice and activated fibrinolysis in diabetic female mice. CANA and DAPA exerted sex-specific effects, which were more pronounced in hyperglycemia. The antithrombotic effect of CANA and DAPA was more noticeable in male mice and could be due to platelet inhibition. The effect on coagulation and fibrinolysis was not clear since an increased coagulation and fibrinolysis were observed only in female mice.

Underlying mechanisms of thrombus formation/growth in atherothrombosis and deep vein thrombosis.

Thrombosis remains a leading cause of death worldwide despite technological advances in prevention, diagnosis, and treatment. The traditional view of arterial thrombus formation is that it is a platelet-dependent process, whereas that of venous thrombus formation is a coagulation-dependent process. Current pathological and basic studies on atherothrombosis and venous thrombosis have revealed the diverse participation of platelet and coagulation activation mechanisms in both thrombus initiation and growth processes during clinical thrombotic events. Atherosclerotic plaque cell-derived tissue factor contributes to fibrin formation and platelet aggregation. The degree of plaque disruption and a blood flow alteration promote atherothrombotic occlusion. While blood stasis/turbulent flow due to luminal stenosis itself initiates venous thrombus formation. The coagulation factor XI-driven propagation phase of blood coagulation plays a major role in venous thrombus growth, but a minor role in hemostasis. These lines of evidence indicate that atherothrombosis onset is affected by the thrombogenic potential of atherosclerotic plaques, the plaque disruption size, and an alteration in blood flow. Upon onset of venous thrombosis, enhancement of the propagation phase of blood coagulation under blood stasis and a hypercoagulable state contribute to large thrombus formation.

Fibrin formation and fractal organization at cationic, anionic, and zwitterionic polymer coated interfaces.

Biomaterial-associated thrombosis remains a persistent challenge whenever medical devices are inserted in blood vessels. The issue is principally addressed by the development of antithrombogenic coatings that prevent the formation of blood clots, e.g. by limiting adsorption of fibrin - the core protein network of a clot. Charged polymers (i.e. polyelectrolytes and zwitterionic polymers) show potential as coating materials for medical devices, and we here investigate these polymer coatings in the context of biomaterial-associated thrombosis. Our findings indicate that fibrin polymerization can yield a surface-dependent distribution of fractal-like branched structures and amorphous aggregates, with surface-induced fibrin formation dominating for anionic polymer interfaces and recruitment of bulk-formed fibrin dominating for cationic polymer interfaces. In addition, we identify coatings containing zwitterionic sulfobetaine groups as promising candidates for antithrombogenic biomaterials.

A Pilot Study Evaluating the Ex Vivo Effects of Varying Factor VIII Concentration on Clot Kinetics and Architecture in Patients With Haemophilia A

Background Haemophilia A (HA) is a bleeding disorder, due to a deficiency in factor VIII (FVIII). These patients are unable to produce a stable fibrin clot in the propagation phase of coagulation as they do not generate sufficient thrombin. The primary treatment for HA in South Africa remains replacement therapy with standard half-life FVIII clotting factor concentrate, aimed at reducing bleeding episodes. Objectives To evaluate the effect of varying concentrations of FVIII on whole blood (WB) clot architecture and kinetics during clot formation in patients with severe HA. Design A cross-sectional study where blood from 20 patients with HA was exposed to FVIII ex vivo and compared to a control group of 20 healthy individuals. Methods Scanning electron microscopy (SEM) was used to study WB clot architecture and thromboelastography® (TEG®) was used to quantify WB clot kinetics. Results Scanning electron microscopy studies revealed that patients with HA have sparse, disorganized fibrin networks with limited crosslinking and red blood cells (RBCs) stacked in rouleaux formation. Haemophilia A blood spiked to a 10 to 15 IU/dL FVIII concentration showed improvements in the organisation of the fibrin network with some altered RBCs. In addition, blood spiked to a 30 to 35 IU/dL FVIII concentration showed an increase in fibrin formation with normal RBCs. Thromboelastography® showed that patients with HA had an increased clot initiation time and decreased clot strength. When spiked to a 10 to 15 IU/dL FVIII concentration the clot kinetic profile showed normalization. However, an increase in FVIII concentration higher than 30 IU/dL showed altered clot architecture and kinetics. Conclusion Based on the current study, FVIII levels at 10 to 15 IU/dL improved clot kinetics but did not normalize the architecture. It may be sufficient for prevention of haemorrhages. Factor VIII levels at 30 to 35 IU/dL resulted in rapid but weaker clot formation. However, at this concentration the clot architecture was normalised which is important for haemostasis. Here it was also evident that the findings of these two modalities (TEG® and SEM) should not be separated but interpreted in conjunction with each other.

Retrospective study of postoperative intraocular pressure and complications in phacoemulsification combined with endoscopic cyclophotocoagulation and phacoemulsification alone in dogs.

Long-term comparative data of phacoemulsification combined with endoscopic cyclophotocoagulation (phaco-ECP) versus phacoemulsification (phaco) alone in dogs are rare. To investigate the effects of ECP on postoperative intraocular pressure (IOP) and complications after phaco in dogs with normal IOP. Medical records of IOP, conjunctival hyperemia, corneal edema, aqueous flare, posterior synechia, intraocular fibrin, and posterior capsule opacification (PCO) formation in 15 canine eyes that underwent phaco-ECP and 36 eyes that underwent phaco alone were evaluated retrospectively. ECP was applied when either the iridocorneal angle or the ciliary cleft was narrow or closed. The IOP of the phaco-ECP group persisted within the normal range postoperatively. The phaco-ECP group had a shorter period of dorzolamide use than did the phaco group. PCO was formed earlier in the phaco-ECP group than in the phaco group. The phaco-ECP group showed more severe corneal edema than the phaco group at every follow-up visit. Posterior synechia was more severe in the phaco-ECP group than in the phaco group from two weeks until the last follow-up. Although ECP might cause more postoperative complications such as corneal edema and posterior synechia, it could effectively reduce the incidence of IOP increase after phaco in dogs with a high risk of postoperative glaucoma.

СОСТОЯНИЕ ПЛАЗМЕННОГО КОМПОНЕНТА СИСТЕМЫ ГЕМОСТАЗА У ИСПЫТУЕМЫХ ДОБРОВОЛЬЦЕВ В ЭКСПЕРИМЕНТЕ С СЕРИЙНЫМ ПРОФИЛАКТИЧЕСКИМ ВРАЩЕНИЕМ НА ЦЕНТРИФУГЕ КОРОТКОГО РАДИУСА

We studied the effects on the human system of plasma hemostasis of sequel rotations on a short-arm centrifuge with equal absolute g value and direction. Participants were 6 normal male volunteers at the age of 25 to 45 years. The volunteers were rotated 7 times in the head-to-pelvis direction (+Gz) at 2.1 g. The first rotation was performed prior to the series; the series of 5 rotations was performed with a 2-day interval between each; the final rotation was performed in 14 days after the series. Citrated plasma was used to investigate the procoagulent component of homeostasis, physiological anticoagulents, and intensity of fibrin formation and fibrinolysis. As compared to baseline data, fibrinogen concentration was increased significantly by 4 % on day 7 post rotations; thrombin time was found decreased by 5 % prior to the 6th rotation. Protein C activity was reduced significantly after rotations 3 and 5 by 8 % and 9 %, respectively. Antithrombin III was reduced by 4 % after rotation 5. Concentration of D-dimer was increased after rotations 5 and 6 by 87 % and 32 %, respectively. Rotations produced minor changes in the levels of pro- and anticoagulents, and also in the intensity of fibrin formation and fibrinolysis, that is these changes were within the physiological norm and reflected adaptive processes in organism.

Tools of the cornea specialist

To report a case of a successful Descemet's membrane endothelial keratoplasty (DMEK) facilitated by the use of intracameral tissue plasminogen activator (tPA) in a 4-year old with posterior polymorphous corneal dystrophy (PPCD).A 4-year old male was referred for bilateral corneal haze and blurry vision. Patient's exam and genetic testing were consistent with a diagnosis of PPCD. Patient was successfully treated with DMEK augmented by the use of intracameral tPA intraoperatively to combat the anterior chamber fibrin formation that can occur in DMEK.To our knowledge, this case represents the youngest reported successful DMEK procedure and the first case describing the use of intracameral tPA intraoperatively to attenuate the anterior chamber fibrin formation that can occur in DMEK.

STANDARDIZATION OF THE PROTEIN CALIBRATORS ISOLATION METHODOLOGY FOR THROMBOPHILIA MARKERS DETECTING IMMUNODIAGNOSTIC TEST SYSTEMS

The most accurate laboratory methods for thrombophilia diagnostics are based on the quantitative determination of the blood plasma specific markers that appear as a result of the coagulation cascade activation. Soluble fibrin and D-dimer belong to the main of the last ones. An alteration in the concentration of such markers can indicate thrombin concentration growth and the formation of soluble oligomeric fibrin. It should be pointed out that simultaneous detection of these markers can establish the correlation between the accumulation of soluble fibrin and fibrinolysis and nowadays is provided only by enzyme-linked immunoassay. Thus, the usage of immunodiagnostic test systems for the detection of thrombophilia markers is highly relevant today. The important components of immunodiagnostic test system are protein calibrators, the isolation standardization of which plays a key role for accurate construction of a calibration curve and obtaining objective results as a consequence. Aim. The objective of this study was to develop the soluble fibrin and D-dimer isolation methodology and its standardization for their further use as the protein calibrators for thrombophilia markers detecting immunodiagnostic test systems. Materials and Methods. Soluble fibrin and D-dimer were isolated from collected human blood by fibrinogen salting out with further fibrin polymerization with thrombin and hydrolysis with plasmin. Quality control of the obtained proteins was carried out using SDS-PAGE and turbidimetric measurements with further checking of the proteins as calibrators for the thrombophilia markers detecting immunoassay. Results. Obtained proteins meet the necessary specifications and can be used as calibrators for immunodiagnostic test systems. Soluble fibrin and D-dimer were checked by SDS-PAGE for the absence of impurities. Turbidimetric measurements showed the polymerization capability of the soluble fibrin and the inhibition of the polymerization by D-dimer. Conclusion. The standardized isolation methodology of soluble fibrin and D-dimer can be used to obtain protein calibrators for appropriate immunodiagnostic test systems.

Overall Hemostatic Potential Assay Detects Risk of Progression to Post-Thrombotic Syndrome in Anticoagulated Patients following Deep Vein Thrombosis.

Deep vein thrombosis (DVT) frequently leads to post-thrombotic syndrome (PTS) which is challenging to predict and prevent. Identifying those at high risk of developing PTS may help to focus preventative strategies. Adults were recruited within 3 months of DVT diagnosis. Blood was sampled during the therapeutic anticoagulation phase. Overall hemostatic potential (OHP) assay, a spectrophotometric assay, was performed on platelet-poor plasma (PPP). In this assay, fibrin formation is triggered by small amounts of thrombin and termed the overall coagulation potential (OCP). Simultaneously, thrombin and tissue plasminogen activator are added to PPP and the resulting fibrin aggregation curve is the overall hemostatic potential (OHP). Fibrinolysis is expressed by the parameter overall fibrinolytic potential (OFP%). Patients were followed up at regular intervals. PTS was diagnosed if the Villalta score was ≥5 at least 3 months after the DVT diagnosis. Results were obtained from 190 patients (53.7% male, mean age 56.9 years). PTS developed in 62 (32.6%) patients. Patients with PTS displayed significantly higher median OCP (45.8 vs. 38.8 units, p = 0.010), OHP (12.8 vs. 9.2 units, p = 0.005) and significantly lower OFP (74.1 vs. 75.6%, p = 0.050). PTS patients had higher neutrophil/lymphocyte ratios (NLR) (2.3 vs. 1.9, p = 0.007). After multivariate analysis, proximal DVT location, history of varicose veins, NLR ≥ 2.6, OHP &gt; 13.0 units and weight &gt;108 kg were independent predictors for PTS. The c-statistic of the multivariate model was 0.77. This pilot study suggests that OHP testing while patients are still anticoagulated may assist in the prediction of PTS development and could assist in prognostication and targeting of preventative measures. However, larger prospective studies are needed to confirm these findings.

Microplastic Effects on Thrombin-Fibrinogen Clotting Dynamics Measured via Turbidity and Thromboelastography.

Micro/nanoplastics, whether manufactured or resulting from environmental degradation, can enter the body through ingestion, inhalation, or dermal pathways. Previous research has found that nanoplastics with diameters of ≤100 nm can translocate into the circulatory system in a dose-dependent manner and potentially impact thrombosis and hemostasis. To investigate the direct effects of microplastics on fibrin clot formation, a simplified ex vivo human thrombin/fibrinogen clot model was utilized. The 100 nm polystyrene particles (non-functionalized [nPS] and aminated [aPS]) were preincubated (0-200 µg/mL) with either thrombin or fibrinogen, and fibrin clot formation was characterized via turbidity and thromboelastography (TEG). When the particles were preincubated with fibrinogen, little effect was observed for aPS or nPS on turbidity or TEG up through 100 µg/mL. TEG results demonstrated a significant impact on clot formation rate and strength, in the case of nPS preincubated with thrombin exhibiting a significant dose-dependent inhibitory effect. In conclusion, the presence of microplastics can have inhibitory effects on fibrin clot formation that are dependent upon both particle surface charge and concentration. Negatively charged nPS exhibited the most significant impacts to clot strength, turbidity, and rate of fibrin formation when first incubated with thrombin, with its impact being greatly diminished when preincubated with fibrinogen in this simplified fibrin clot model.

The activated partial thromboplastin time-clot waveform analysis in hemophilia: Does it help in differentiation?

The clot waveform analysis (CWA) provide valuable information beyond clotting time. The present study was planned to assess whether the activated partial thromboplastin time (aPTT)-CWA can differentiate between hemophilia A (HA), hemophilia B (HB), or hemophilia A with inhibitors (HAWI). The aPTT-CWA was generated by an optical detection system (ACL-TOP™ 500 coagulation analyzer) and the other tests were performed as per instructions from the manufacturer in the kit. A total of 75 samples (47-HA, 16-HAWI, and 12-HB) with prolonged aPTT were recruited. On analyzing the quantitative aPTT-CWA data of HA (non-inhibitors) and HB samples, the width of acceleration 1 [+] peak was the differentiating finding. Among the significant parameters, the second derivative [+] peak was lower in both mild and moderate HA, equating to HB. The time for the height of 1/2 fibrin formation and width of velocity was significantly higher in mild, moderate and severe HA. The study did not show any significant differentiating finding while comparing HAWI and hemophilia A non-inhibitors (HANI). In the subgroups of HAWI and HANI with aPTT <70 s and 70-100 s, the second derivative [+] peak (2A) was higher and the time for the height of 1/2 fibrin formation (1C) was lesser in HAWI. The aPTT-CWA parameters may be supportive for the differentiation of hemophilia including its severity and the existence of inhibitors.