Markers Of Fibrinolysis Research Articles

Automated measurement of coagulation and fibrinolytic activation markers: Outcomes in coronavirus disease 2019 (COVID-19) patients.

BackgroundSevere coronavirus disease 2019 (COVID‐19) is characterized by marked hypoxaemia and lung oedema, often accompanied by disordered blood coagulation and fibrinolytic systems, endothelial damage and intravascular fibrin deposition.Patients/MethodsWe present a retrospective observational study of 104 patients admitted to hospital with COVID‐19. Plasma samples were collected within 72 h of admission. In addition to routine coagulation and haematology testing, soluble thrombomodulin (sTM), thrombin‐antithrombin (TAT), tissue plasminogen activator‐plasminogen activator inhibitor 1 complex (tPAI‐C) and plasmin‐α2 antiplasmin complex (PIC) were performed by automated chemiluminescent enzyme immunoassays.ResultsSignificantly higher levels of D‐dimer, TAT, sTM and tPAI‐C were observed in non‐survivors compared to survivors. To confirm which parameters were independent risk factors for mortality, multiple logistic regression was performed on D‐dimer, TAT. sTM, tPAI‐C and PIC data. Only increasing sTM was significantly associated with mortality, with an odds ratio of 1.065 for each 1.0 TU/mL increment (95% CI 1.025–1.115).ConclusionsOf the haemostatic variables measured, sTM, which can be rapidly assayed, is the best independent predictor of mortality in patients hospitalized with COVID‐19, and this suggests that endothelial dysfunction plays an important role in disease progression.

Prospective randomized controlled trial on the effectiveness of low-dose and high-dose intravenous tranexamic acid in reducing perioperative blood loss in single-level minimally invasive transforaminal lumbar interbody fusion

A prospective randomized controlled trial was conducted to study the effectiveness and safety of intravenous different doses tranexamic acid (TXA) in single-level unilateral minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF). The patients treated with single-level unilateral MIS-TLIF between September 2019 and October 2020 were enrolled and randomly classified into low-dose TXA (LD) group (n=39), high-dose TXA (HD) group (n=39), and placebo-controlled (PC) group (n=38). The LD, HD, and PC groups received intravenous TXA 20 mg/kg, TXA 50 mg/kg, the same volume of normal saline at 30 minute before skin incision after general anesthesia, respectively. There was no significant difference on baseline characteristics and preoperative laboratory results among 3 groups (P>0.05), including age, gender, body mass index, surgical segments, hematocrit (HCT), hemoglobin (HGB), prothrombin time (PT), international normalized ratio (INR), D-dimer, fibrin degradation products (FDP), activated partial prothromboplastin time (APTT), alanine aminotransferase (ALT), aspartate aminotransferase (AST), creatinine (Cr), urea. The intraoperative blood loss (IBL), postoperative drainage volume, operation time, total blood loss (TBL), hidden blood loss (HBL), blood transfusion, hematological examination indexes on the first day after operation, and the incidence of complications within 1 month were compared among the 3 groups. There were 3, 2, and 4 patients in the LD, HD, and PC groups who underwent autologous blood transfusion, respectively, and there was no allogeneic blood transfusion patients in the 3 groups. There was no significant difference in IBL, postoperative drainage volume, and operation time between groups (P>0.05). The TBL, HBL, and the decreased value of HGB in LD and HD groups were significantly lower than those in PC group (P<0.05), and TBL and HBL in HD group were significantly lower than those in LD group (P<0.05); the decreased value of HGB between LD group and HD group showed no significant difference (P>0.05). On the first day after operation, D-dimer in LD and HD groups were significantly lower than that in PC group (P<0.05); there was no significant difference between LD and HD groups (P>0.05). There was no significant difference in other hematological indexes between groups (P>0.05). All patients were followed up 1 month, and there was no TXA-related complication such as deep venous thrombosis of lower extremity, pulmonary embolism, and epilepsy in the 3 groups. Intravenous administration of TXA in single-level unilateral MIS-TLIF is effective and safe in reducing postoperative TBL and HBL within 1 day in a dose-dependent manner. Also, TXA can reduce postoperative fibrinolysis markers and do not increase the risk of thrombotic events, including deep venous thrombosis and pulmonary embolism.

Evaluation of novel coagulation and platelet function assays in patients with chronic kidney disease

BackgroundHemostasis evaluation in chronic kidney disease (CKD) is critical for optimal management of thrombotic and bleeding events. Standard coagulation screens are inadequate for predicting coagulopathy in CKD. ObjectiveTo evaluate hemostasis parameters in patients with different stages of CKD using novel coagulation assays. Patients/MethodsCross‐sectional study of 30 healthy controls (HC) and 120 CKD patients (10 Stage 2, 20 Stage 3, 20 Stage 4, 20 Stage 5 not requiring renal replacement therapy, 20 transplant, 10 newly started on hemodialysis [HD], 20 established on HD). Standard laboratory tests were performed in addition to rotational thromboelastometry (ROTEM), multiple electrode aggregometry (MEA), thrombin generation assays, D‐dimer, and markers of thrombogenesis (thrombin‐antithrombin [TAT]), fibrinolysis, and endothelial activation (intercellular adhesion molecule‐1 [ICAM‐1]). ResultsD‐dimer, TAT, and ICAM‐1 concentrations were significantly higher in patients with CKD than HC (P < .01). ROTEM maximum clot firmness was significantly higher in patients than in HC (P < .01). In CKD Stage 5 patients (pre‐HD and started HD) adenosine diphosphate and thrombin receptor activating peptide MEA tests were significantly lower than HC indicating platelet aggregation defect (P < .05). Multivariate analysis confirmed the direct effect of estimated glomerular filtration rate (eGFR) in the variance of ROTEM and MEA tests. Endogenous thrombin potential and peak thrombin were not statistically different between groups, but Stage 5 CKD patients had prolonged lag time (7.91 vs. 6.33, P < .001) and time to thrombin peak (10.8 vs. 9.5, P < .05) compared to HC. ConclusionsPatients with CKD exhibit features of concomitant hypercoagulability measured by ROTEM and platelet dysfunction measured with MEA. eGFR was an independent determinant of platelet dysfunction and hypercoagulability.

Serum D-dimer level as a predictor of neurological functional prognosis in cases of head injuries caused by road traffic accidents

BackgroundThe number of traffic fatalities is declining in Japan; however, a large proportion of head injuries are still attributable to traffic accidents. Severe head trauma may cause progressive and devastating coagulopathy owing to exacerbated coagulation and fibrinolysis, which results in massive bleeding and poor patient outcomes. D-dimer is a fibrinolytic marker, which remarkably increases in severe coagulopathy due to the exacerbated fibrinolytic system. Because the degree of coagulopathy is associated with patient outcomes, the D-dimer level is a useful prognostic predictor in patients with head trauma. However, the usefulness of D-dimer in cases of head trauma caused by road traffic accidents remains inadequately explored. In this study, we investigated the relationship between D-dimer levels and outcomes in head injuries caused by traffic accidents.MethodsWe extracted data on traffic injuries from Japan Neuro-Trauma Data Bank Project 2015, which is a prospective multicenter registry of head injuries. The analysis included 335 individuals with no missing data. The outcome variable was the score of the Glasgow Outcome Scale (GOS), a neurological outcome index. The participants were categorized into the favorable outcome (GOS score ≥ 4) and poor outcome (GOS score ≤ 3) groups. The serum D-dimer levels at the time of admission were divided into four categories at the quartiles, and the reference category was less than the first quartile (< 17.4 µg/mL). We performed a logistic regression analysis with GOS as the dependent variable and D-dimer as a predictor and performed a multivariate analysis that was adjusted for 10 physiological parameters.ResultsIn the univariate analysis, all groups with serum D-dimer values ≥ 17.4 μg/dL showed significantly poorer outcomes than those of the reference group. In the multivariate analysis, after adjusting for other factors, D-dimer levels ≥ 89.3 μg/dL were an independent predictor of poor outcome.ConclusionAfter adjusting for physiological parameters, high serum D-dimer levels can be an independent factor for predicting neurological prognosis in head trauma caused by road traffic accidents.

Associations between hemostatic markers and mortality in COVID-19 – Compounding effects of D-dimer, antithrombin and PAP complex

In this single-center cohort study, we applied a panel of laboratory markers to characterize hemostatic function in 217 consecutive patients that underwent testing for COVID-19 as they were admitted to Linköping University Hospital between April and June 2020. In the 96 patients that tested positive for SARS-CoV-2 (COVID-19+), the cumulative incidences of death and venous thromboembolism were 24.0% and 19.8% as compared to 12.4% (p = 0.031) and 11.6% (p = 0.13) in the 121 patients that tested negative (COVID-19−). In COVID-19+ patients, we found pronounced increases in plasma levels of von Willebrand factor (vWF) and fibrinogen. Excess mortality was observed in COVID-19+ patients with the following aberrations in hemostatic markers: high D-dimer, low antithrombin or low plasmin-antiplasmin complex (PAP) formation, with Odds Ratios (OR) for death of 4.7 (95% confidence interval (CI95) 1.7–12.9; p = 0.003) for D-dimer >0.5 mg/L, 5.9 (CI95 1.8–19.7; p = 0.004) for antithrombin (AT) ˂0.85 kIU/l and 4.9 (CI95 1.3–18.3; p = 0.019) for PAP < 1000 μg/L. Compounding increases in mortality was observed in COVID-19+ patients with combined defects in markers of fibrinolysis and coagulation, with ORs for death of 15.7 (CI95 4.3–57; p < 0.001) for patients with PAP <1000 μg/L and D-dimer >0.5 mg/L and 15.5 (CI95 2.8–87, p = 0.002) for patients with PAP <1000 μg/L and AT ˂0.85 kIU/L. We observed an elevated fraction of incompletely degraded D-dimer fragments in COVID-19+ patients with low PAP, indicating impaired fibrinolytic breakdown of cross-linked fibrin.

Activation of the Carboxypeptidase U (CPU, TAFIa, CPB2) System in Patients with SARS-CoV-2 Infection Could Contribute to COVID-19 Hypofibrinolytic State and Disease Severity Prognosis.

Coronavirus disease 2019 (COVID-19) is a viral lower respiratory tract infection caused by the highly transmissible and pathogenic SARS-CoV-2 (severe acute respiratory-syndrome coronavirus-2). Besides respiratory failure, systemic thromboembolic complications are frequent in COVID-19 patients and suggested to be the result of a dysregulation of the hemostatic balance. Although several markers of coagulation and fibrinolysis have been studied extensively, little is known about the effect of SARS-CoV-2 infection on the potent antifibrinolytic enzyme carboxypeptidase U (CPU). Blood was collected longitudinally from 56 hospitalized COVID-19 patients and 32 healthy controls. Procarboxypeptidase U (proCPU) levels and total active and inactivated CPU (CPU+CPUi) antigen levels were measured. At study inclusion (shortly after hospital admission), proCPU levels were significantly lower and CPU+CPUi antigen levels significantly higher in COVID-19 patients compared to controls. Both proCPU and CPU+CPUi antigen levels showed a subsequent progressive increase in these patients. Hereafter, proCPU levels decreased and patients were, at discharge, comparable to the controls. CPU+CPUi antigen levels at discharge were still higher compared to controls. Baseline CPU+CPUi antigen levels (shortly after hospital admission) correlated with disease severity and the duration of hospitalization. In conclusion, CPU generation with concomitant proCPU consumption during early SARS-CoV-2 infection will (at least partly) contribute to the hypofibrinolytic state observed in COVID-19 patients, thus enlarging their risk for thrombosis. Moreover, given the association between CPU+CPUi antigen levels and both disease severity and duration of hospitalization, this parameter may be a potential biomarker with prognostic value in SARS-CoV-2 infection.

Endotheliopathy is Associated with a 24-hour Fibrinolysis Phenotype Described by Low TEG Lysis and High D-Dimer after Trauma: a Secondary Analysis of the PROPPR Study.

Determine associations between biomarkers of endotheliopathy, 24-hour fibrinolysis phenotypes and clinical outcomes after trauma. The vascular endothelium is a critical regulator of hemostasis and organ function. The relationship between markers of endotheliopathy and fibrinolysis following trauma has not been evaluated. We performed a secondary analysis of prospectively collected biomarker data in the Pragmatic Randomized Optimal Platelet and Plasma Ratios (PROPPR) randomized controlled trial. We stratified subjects by 24-hour thromboelastography (TEG) percent clot lysis (LY30) and plasma D-dimer (DD) levels and evaluated differences in endotheliopathy biomarkers and clinical outcomes between subjects with one of four 24-hour fibrinolysis phenotypes: LY30 0.9-2.9% (LY30norm), LY30 >2.9% (LY30high), LY30 <0.9% and low DD (LY30low+DDlow), and LY30 <0.9% and high DD (LY30low+DDhigh). The analysis included 168 subjects with LY30norm, 32 with LY30high, 147 with LY30low+DDlow and 124 with LY30low+DDhigh. LY30low+DDhigh subjects had greater injury severity and a higher incidence of severe head injury, multiorgan failure (MOF), and mortality than the other phenotypes. All endotheliopathy biomarkers were significantly higher in the LY30low+DDhigh phenotype. Adjusting for injury severity, mechanism and head trauma, 24-hour angiopoietin-2 and soluble thrombomodulin were independently associated with the LY30low+DDhigh phenotype. Both endothelial biomarkers were discriminating for MOF. Subjects with thrombomodulin level >9.5 ng/mL and angiopoietin-2 level >3.6 ng/mL accounted for 64% of subjects who developed MOF. In a multicenter trauma cohort, subjects with a fibrinolysis phenotype characterized by low TEG lysis and elevated DD 24 hours after injury have significantly worse endotheliopathy and clinical outcomes. Our findings support mechanistic evaluations of the role of the endothelium in fibrinolysis dysregulation that may drive late-stage organ injury.

Omega-3 fatty acids attenuate cardiovascular effects of short-term exposure to ambient air pollution

BackgroundExposure to air pollution is associated with elevated cardiovascular risk. Evidence shows that omega-3 polyunsaturated fatty acids (omega-3 PUFA) may attenuate the adverse cardiovascular effects of exposure to fine particulate matter (PM2.5). However, it is unclear whether habitual dietary intake of omega-3 PUFA protects against the cardiovascular effects of short-term exposure to low-level ambient air pollution in healthy participants. In the present study, sixty-two adults with low or high dietary omega-3 PUFA intake were enrolled. Blood lipids, markers of vascular inflammation, coagulation and fibrinolysis, and heart rate variability (HRV) and repolarization were repeatedly assessed in 5 sessions separated by at least 7 days. This study was carried out in the Research Triangle area of North Carolina, USA between October 2016 and September 2019. Daily PM2.5 and maximum 8-h ozone (O3) concentrations were obtained from nearby air quality monitoring stations. Linear mixed-effects models were used to assess the associations between air pollutant concentrations and cardiovascular responses stratified by the omega-3 intake levels.ResultsThe average concentrations of ambient PM2.5 and O3 were well below the U.S. National Ambient Air Quality Standards during the study period. Significant associations between exposure to PM2.5 and changes in total cholesterol, von Willebrand factor (vWF), tissue plasminogen activator, D-dimer, and very-low frequency HRV were observed in the low omega-3 group, but not in the high group. Similarly, O3-associated adverse changes in cardiovascular biomarkers (total cholesterol, high-density lipoprotein, serum amyloid A, soluable intracellular adhesion molecule 1, and vWF) were mainly observed in the low omega-3 group. Lag-time-dependent biphasic changes were observed for some biomarkers.ConclusionsThis study demonstrates associations between short-term exposure to PM2.5 and O3, at concentrations below regulatory standard, and subclinical cardiovascular responses, and that dietary omega-3 PUFA consumption may provide protection against such cardiovascular effects in healthy adults.

Early recognition of sepsis-induced coagulopathy using the C2PAC index: a ratio of soluble type C lectin-like receptor 2 (sCLEC-2) level and platelet count

C-type lectin-like receptor 2 (CLEC-2) is a platelet-activated receptor expressed on the surface of platelet membranes. Soluble CLEC-2 (sCLEC-2) has been receiving attention as a predictive marker for thrombotic predisposition. The present study examined the relationship between sCLEC-2 level and degree of coagulation disorder in septic patients. Seventy septic patients were divided into the sepsis-induced disseminated intravascular coagulation (DIC) (SID) group (n = 44) and non-SID group (n = 26). The sCLEC-2 levels were compared between the two groups. Because we suspected that the sCLEC-2 level was affected by the platelet count, we calculated the sCLEC-2/platelet count ratio (C2PAC index). We further divided septic patients into four groups using the Japanese Association for Acute Medicine (JAAM) DIC scoring system (DIC scores: 0–1, 2–3, 4–5, and 6–8). The C2PAC index was significantly higher in the SID group (2.6 ± 1.7) compared with the non-SID group (1.2 ± 0.5) (P < .001). The C2PAC indexes in the four JAAM DIC score groups were 0.9 ± 0.3, 1.1 ± 0.3, 1.7 ± 0.7, and 3.6 ± 1.0, respectively, and this index increased significantly as the DIC score increased (P < .001). According to the receiver-operating curve analysis, the area under the curve (AUC) and optimal cutoff value for the diagnosis of SID were 0.8051 and 1.4 (sensitivity, 75.0%; specificity, 76.9%), respectively. When the C2PAC index and D-dimer level, one of the main fibrinolytic markers, were selected as predictive markers for SID diagnosis in stepwise multiple logistic regression analysis, it was possible to diagnose SID with a high probability (AUC, 0.9528; sensitivity, 0.9545; specificity, 0.8846). The C2PAC index is a useful predictor of SID progression and diagnosis in septic patients.

Age, sex and racial differences in fibrin formation and fibrinolysis within the healthy population.

Increased fibrin generation and reduced fibrinolytic potential have been detected using global coagulation assays in several hypercoagulable states including cardiovascular disease and venous thromboembolism. We aimed in this study to define the impact of age, sex and race on fibrin generation and lysis using the Overall Haemostatic Potential (OHP) assay in a group of stringently defined healthy adults. Healthy adult patients not receiving anticoagulation and without a history of thrombotic disease were prospectively recruited. Iindividuals with cardiovascular risk factors (e.g. hypertension, diabetes, smoking), receiving hormonal therapy, antiplatelet agents or with abnormal routine blood tests were also excluded. Platelet-poor plasma was obtained and the OHP assay, which evaluates fibrin formation with and without tissue plasminogen activator, was performed on all plasma samples. 144 healthy subjects (34.7% male) with median age 42 years (interquartile range 20, 77) were recruited. After multivariate analysis, age at least 50 years and female sex were associated with significantly increased fibrin generation parameters (overall coagulation potential, OHP, maximum optical density, fibrin) as well as reduced markers of fibrinolysis (overall fibrinolytic potential and time-to-50% lysis). There were no significant differences in OHP parameters between whites, East Asians and South Asians after accounting for age and sex. This study defines age, sex and racial differences of fibrin generation and fibrinolysis as measured by the OHP assay in a sample of healthy subjects. Further studies are warranted in diseased populations, where there is growing awareness of the role of global coagulation assay in defining prothrombotic and hypofibrinolytic states.

Exacerbation of Thrombotic Responses to Silver Nanoparticles in Hypertensive Mouse Model.

With advent of nanotechnology, silver nanoparticles, AgNPs owing majorly to their antibacterial properties, are used widely in food industry and biomedical applications implying human exposure by various routes including inhalation. Several reports have suggested AgNPs induced pathophysiological effects in a cardiovascular system. However, cardiovascular diseases such as hypertension may interfere with AgNPs-induced response, yet majority of them are understudied. The aim of this work was to evaluate the thrombotic complications in response to polyethylene glycol- (PEG-) coated AgNPs using an experimental hypertensive (HT) mouse model. Saline (control) or PEG-AgNPs (0.5 mg/kg) were intratracheally (i.t.) instilled four times, i.e., on days 7, 14, 21, and 28 post-angiotensin II-induced HT, or vehicle (saline) infusion. On day 29, various parameters were assessed including thrombosis in pial arterioles and venules, platelet aggregation in whole blood in vitro, plasma markers of coagulation, and fibrinolysis and systemic oxidative stress. Pulmonary exposure to PEG-AgNPs in HT mice induced an aggravation of in vivo thrombosis in pial arterioles and venules compared to normotensive (NT) mice exposed to PEG-AgNPs or HT mice given saline. The prothrombin time, activated partial thromboplastin time, and platelet aggregation in vitro were exacerbated after exposure to PEG-AgNPs in HT mice compared with either NT mice exposed to nanoparticles or HT mice exposed to saline. Elevated concentrations of fibrinogen, plasminogen activator inhibitor-1, and von Willebrand factor were seen after the exposure to PEG-AgNPs in HT mice compared with either PEG-AgNPs exposed NT mice or HT mice given with saline. Likewise, the plasma levels of superoxide dismutase and nitric oxide were augmented by PEG-AgNPs in HT mice compared with either NT mice exposed to nanoparticles or HT mice exposed to saline. Collectively, these results demonstrate that PEG-AgNPs can potentially exacerbate the in vivo and in vitro procoagulatory and oxidative stress effect in HT mice and suggest that population with hypertension are at higher risk of the toxicity of PEG-AgNPs.

(More than) doubling down: Effective fibrinolysis at a reduced rt-PA dose for catheter-directed thrombolysis combined with histotripsy.

Deep vein thrombosis is a major source of morbidity and mortality worldwide. For acute proximal deep vein thrombosis, catheter-directed thrombolytic therapy is an accepted method for vessel recanalization. Thrombolytic therapy is not without risk, including the potential for hemorrhagic bleeding that increases with lytic dose. Histotripsy is a focused ultrasound therapy that generates bubble clouds spontaneously in tissue at depth. The mechanical activity of histotripsy increases the efficacy of thrombolytic therapy at doses consistent with current pharmacomechanical treatments for venous thrombosis. The objective of this study was to determine the influence of lytic dose on histotripsy-enhanced fibrinolysis. Human whole blood clots formed in vitro were exposed to histotripsy and a thrombolytic agent (recombinant tissue plasminogen activator, rt-PA) in a venous flow model perfused with plasma. Lytic was administered into the clot via an infusion catheter at concentrations ranging from 0 (control) to 4.54 μg/mL (a common clinical dose for catheter-directed thrombolysis). Following treatment, perfusate samples were assayed for markers of fibrinolysis, hemolysis, and intact red blood cells and platelets. Fibrinolysis was equivalent between the common clinical dose of rt-PA (4.54 μg/mL) and rt-PA at a reduction to one-twentieth of the common clinical dose (0.23 μg/mL) when combined with histotripsy. Minimal changes were observed in hemolysis for treatment arms with or without histotripsy, potentially due to clot damage from insertion of the infusion catheter. Likewise, histotripsy did not increase the concentration of red blood cells or platelets in the perfusate following treatment compared to rt-PA alone. At the highest lytic dose, a refined histotripsy exposure scheme was implemented to cover larger areas of the clot. The updated exposure scheme improved clot mass loss and fibrinolysis relative to administration of lytic alone. Overall, the data collected in this study indicate the rt-PA dose can be reduced by more than a factor of ten and still promote fibrinolysis when combined with histotripsy.

Impact of Off-Label Under-Dose Direct Oral Anticoagulant on Coagulation and Fibrinolytic Markers in Patients with Atrial Fibrillation

Impact of Off-Label Under-Dose Direct Oral Anticoagulant on Coagulation and Fibrinolytic Markers in Patients with Atrial Fibrillation

Both plasma basic carboxypeptidases, carboxypeptidase B2 and carboxypeptidase N, regulate vascular leakage activity in mice

BackgroundKallikrein is generated when the contact system is activated, subsequently cleaving high molecular weight kininogen to bradykinin (BK). BK binds to bradykinin receptor 2, causing vascular leakage. BK is inactivated by proteolysis by the plasma carboxypeptidase B2 and N (CPB2 and CPN). CPN is constitutively active but CPB2 is generated from its zymogen, proCPB2. ObjectivesDetermine the role of CPB2 and CPN in the regulation of vascular leakage. MethodsMice deficient in CPB2, CPN, or both (Cpb2−/−, Cpn−/−, and Cpb2−/−/Cpn−/−) were compared with wild‐type mice (WT) in a model of vascular leakage caused by skin irritation. In some experiments, mice were pretreated with antibodies that prevent activation of proCPB2. ResultsSkin irritation increased vascular leakage most in Cpb2−/−/Cpn−/−, less in Cpb2−/− and Cpn−/−, and least in WT mice. There was no difference in vascular leakage without the challenge. Antibodies inhibiting activation of proCPB2 by plasmin, but not by the thrombin/thrombomodulin complex, increased vascular leakage to the level seen in Cpb2−/− mice. There was no change in levels of markers of coagulation and fibrinolysis. ConclusionsBradykinin is inactivated by both CPB2 and CPN independently. Plasmin is the activator of proCPB2 in this model. Mice lacking both plasma carboxypeptidases have more vascular leak than those lacking either alone. Although BK levels were not determined, BK is the likely substrate for CPB2 and CPN in this model.

Evaluation of Markers of Fibrinolysis and Coagulation in Pregnant Women with Human Immunodeficiency Virus

Evaluation of Markers of Fibrinolysis and Coagulation in Pregnant Women with Human Immunodeficiency Virus

A Pharmacokinetic and Plasmin-Generation Pharmacodynamic Assessment of a Tranexamic Acid Regimen Designed for Cardiac Surgery With Cardiopulmonary Bypass

To examine the pharmacokinetics (PK) and pharmacodynamics of a tranexamic (TXA) regimen designed for cardiac surgery with cardiopulmonary bypass (CPB). A pilot study quantifying TXA concentrations, fibrinolysis markers, and a plasmin- generation (PG) assay. For comparison, PG assay was performed on pooled normal plasma (PNP) with varying TXA concentrations. A single-center, tertiary, academic medical center. Twenty patients undergoing cardiac surgery with CPB for valve surgery and/or coronary artery bypass grafting. TXA 100 mg/h infusion for 5 hours starting before incision; 1 g TXA in CPB prime and 1 g TXA at CPB end prior to heparin reversal. The PK fit a 2-compartment disposition model. TXA concentrations were above 15 mg/L in all patients during CPB through 2 hours post-TXA infusion. During and after CPB, the TXA regimen decreased the median peak PG by 60% (95% confidence interval [CI], 56%-62%). Lowest median peak PG occurred 15 minutes postprotamine. Peak median D-dimer level of 1.24 (0.95-1.71; 95% CI) mg/L occurred at 15 minutes postprotamine and baseline-adjusted ΔD dimer correlated with increased CPB time (p=0.004) and lower TXA level (p=0.001). The median 24-hour chest tube output was 447 (330-664; 95% CI) mL. PG assay on PNP revealed a plateau inhibition at 5 mM TXA (786 mg/L). This regimen, with total perioperative dose of 2.5 grams, provided TXA concentrations above 15 mg/L for all patients from CPB initiation through 2 hours post-TXA. PG was significantly inhibited (p < 0.0001) during and after CPB, with maximum inhibition measured at 15 minutes after protamine administration.

Assessment of fibrinolytic markers in patients with deep vein thrombosis

The association of the fibrinolytic markers with deep vein thrombosis (DVT) is still a matter of debate. The present study aimed to investigate the association between fibrinolytic markers and DVT. This observational study recruited 52 adult cases with lower limb DVT and 52 healthy adult volunteers as controls. The quantitative determination of plasminogen activator inhibitor-1 (PAI-1), plasminogen, thrombin activable fibrinolysis inhibitor (TAFI), tissue plasminogen activator (tPA) and α2-antiplasmin (α2-AP) was performed by ELISA. TAFI, plasminogen and t-PA were significantly higher in cases than controls and PAI-1 was significantly lower in cases than controls. In addition, TAFI, plasminogen and t-PA levels were significantly increased in unprovoked and idiopathic DVT cases than controls. The present study suggests that the fibrinolytic markers tested in patients with a remote history of DVT are different than in individuals with no history of DVT and, with further study, may prove useful as screening assays for DVT risk.

The influence of dietary intake of omega-3 polyunsaturated fatty acids on the association between short-term exposure to ambient nitrogen dioxide and respiratory and cardiovascular outcomes among healthy adults

BackgroundShort-term exposure to ambient nitrogen dioxide (NO2) is associated with adverse respiratory and cardiovascular outcomes. Supplementation of omega-3 polyunsaturated fatty acids (PUFA) has shown protection against exposure to fine particulate matter. This study aims to investigate whether habitual omega-3 PUFA intake differentially modify the associations between respiratory and cardiovascular responses and short-term exposure to ambient NO2.MethodsSixty-two healthy participants were enrolled into low or high omega-3 groups based on their habitual omega-3 PUFA intake. Each participant was repeatedly assessed for lung function, blood lipids, markers of coagulation and fibrinolysis, vascular function, and heart rate variability (HRV) in up to five sessions, each separated by at least 7 days. This study was carried out in the Research Triangle area of North Carolina, USA between October 2016 and September 2019. Daily ambient NO2 concentrations were obtained from an area air quality monitoring station on the day of outcome assessment (Lag0), 4 days prior (Lag1-4), as well as 5-day moving average (5dMA). The associations between short-term exposure to NO2 and the measured indices were evaluated using linear mixed-effects models stratified by omega-3 levels and adjusted by covariates including relative humidity and temperature.ResultsThe average concentration of ambient NO2 during the study periods was 5.3±3.8 ppb which was below the National Ambient Air Quality Standards (NAAQS). In the high omega-3 group, an interquartile range (IQR) increase in short-term NO2 concentrations was significantly associated with increased lung function [e.g. 1.2% (95%CI: 0.2%, 2.2%) in FVC at lag1, 2.6% (95%CI: 0.4%, 4.8%) in FEV1 at 5dMA], decreased blood lipids [e.g. -2.6% (95%CI: -4.4%, -0.9%) in total cholesterol at lag2, -3.1% (95%CI: -6.1%, 0.0%) in HDL at 5dMA, and -3.1% (95%CI: -5.5%, -0.7%) in LDL at lag2], improved vascular function [e.g. 8.9% (95%CI: 0.6%, 17.2%) increase in FMD and 43.1% (95%CI: -79.8%, -6.3%) decrease in endothelin-1 at 5dMA], and changed HRV parameters [e.g. -7.2% (95%CI: -13.6%, -0.8%) in HFn and 13.4% (95%CI: 0.2%, 28.3%) in LF/HF ratio at lag3]. In the low omega-3 group, an IQR increase in ambient NO2 was associated with elevations in coagulation markers (von Willebrand Factor, D-dimer) and a decrease in HRV (very-low frequency); however, null associations were observed between short-term NO2 exposure and changes in lung function, blood lipids, and vascular function.ConclusionsThe results in this study imply that dietary omega-3 PUFA consumption may offer respiratory and vascular benefits in response to short-term exposure of healthy adults to NO2 levels below the NAAQS.Trial registrationClinicalTrials.gov (NCT02921048).

Abstract 11443: Where NO 2 Meets Omega-3 Polyunsaturated Fatty Acids: Health Impact of Short-Term Ambient Air Pollution Exposure in Healthy Adults

Introduction: Exposure to ambient nitrogen dioxide (NO 2 ) is associated with adverse respiratory and cardiovascular outcomes. Supplementation of omega-3 polyunsaturated fatty acids (PUFA) has shown health benefits against exposure to air pollution. Hypothesis: Dietary omega-3 PUFA intake offers cardiovascular and respiratory benefits against short-term exposure to ambient NO 2 in healthy adults. Methods: Sixty-two healthy participants were enrolled into low or high omega-3 groups based on their habitual dietary omega-3 PUFA intake. Each participant was repeatedly assessed for blood lipids, markers of coagulation and fibrinolysis, vascular function, heart rate variability (HRV), and lung function up to five times separated by at least 7 days between October 2016 and September 2019. Daily ambient NO 2 concentrations were obtained from nearby air quality monitoring stations. The associations between NO 2 concentrations and the measured biomarkers were evaluated using the linear mixed-effects models stratified by the omega-3 intake levels. Results: In the high omega-3 group, an IQR increase in NO 2 concentrations was associated with reductions in total cholesterol at lag2 [-2.6% (-4.4, -0.9)], LDL at lag2 [-3.1% (-5.5, -0.7)], and HDL at lag1 [-2.4% (-4.4, -0.3)] and lag2 [-2.0% (-3.8, -0.1)]; increases in flow-mediated dilatation of brachial artery at lag1[5.7% (0.1, 11.2)] and lag2 [5.7% (0.8, 10.6)]; decreases in plasma levels of endothelin-1at lag3 [-25.6% (-50.0, -1.2)] and lag4 [-22.9% (-45.9, -0.01)]; decreased high frequency (HFn) of HRV [-7.2% (-13.6, -0.8)] and increased LF/HF ratio [13.4% (0.2, 28.3)] at lag3; as well as increased lung function. In the low omega-3 group, blood lipids, vascular function biomarkers and lung function were not significantly associated with NO 2 exposure. However, NO 2 exposure was associated with elevations in coagulation markers (von Willebrand Factor and D-dimer) and a decrease in very-low frequency of HRV at lag0 in the low omega-3 group. Conclusions: The results imply that high dietary omega-3 PUFA intake may offer benefits to cardiovascular and respiratory health in response to exposure to low-level ambient NO 2 in healthy adults. THIS ABSTRACT OF A PROPOSED PRESENTATION DOES NOT NECESSARILY REFLECT EPA POLICY.

COVID-19 Is Associated with Endothelial Dysfunction and Enhanced Plasma Thrombin Generation Despite Pharmacological Thromboprophylaxis

BackgroundHospitalised patients with severe COVID-19 (requiring critical care level support) appear to be at increased risk of thrombosis despite standard pharmacological thromboprophylaxis. The magnitude of thrombotic risk in patients with COVID-19 of moderate severity (not requiring critical care) is less clear. The optimal approach to thromboprophylaxis (and the role of intensified thromboprophylaxis) remains to be determined.Evidence of endothelial dysfunction has been widely reported in COVID-19 (particularly in severe COVID) and this may contribute to hypercoagulability.AimTo assess differences in patterns of hypercoagulability and endothelial dysfunction between a group of patients with moderate COVID-19 and a group of age-matched hospitalized patients (SARS-CoV-2 PCR negative) receiving low molecular weight heparin (LMWH) thromboprophylaxis.MethodsBlood was collected from individuals admitted to hospital with COVID-19 of moderate severity (not requiring critical care level support) and a group of age-matched patients admitted with infective/inflammatory illness (SARS-CoV-2 PCR negative). All subjects received standard-dose LMWH thromboprophylaxis, with blood drawn at 12 hours post-dose (and with measurement of anti-FXa activity levels). Circulating levels of endothelial & fibrinolytic markers including ICAM, PAI-1, VCAM, soluble thrombomodulin (sTM), and tissue plasminogen activator (tPA) were determined by ELISA. Thrombin generation (TG) in platelet-poor plasma was assessed by calibrated automated thrombography in the presence of tissue factor (Final concentration, 1pM & 5pM), thrombomodulin (TM) (Final concentration, 6.25nM), and an inhibitory anti-tissue factor pathway inhibitor antibody (anti-TFPI; Final concentration 100μg/mL).Results14 COVID-19 positive subjects and 11 hospitalized controls were recruited. There were no differences in mean age (69.7±4.5 vs 61.6±4.7 years; p= 0.2) or mean Body mass index (25.7±1.1 vs 22.7±1.2 Kg/m2; p=0.1) between groups. No COVID-19 patient or control required critical care support. In the COVID group, radiological evidence of pneumonitis [diffuse (n=3) or peripheral infiltrates (n=7)] was present in the majority of cases. None of the COVID-19 cases were requiring supplemental oxygen at the time of recruitment.All controls were admitted with either respiratory or urinary infection [radiological evidence of pneumonia in 4/11; supplemental oxygen requirement in 2/11, (28-36% FiO2 via nasal cannula)].Plasma levels of sTM, ICAM, PAI-1 & VCAM were similar in both groups. Levels of t-PA were significantly higher in the COVID group (8.31±4.35 vs 4.91±2.37 ng/mL; p= 0.005). Despite similar plasma anti-Xa activity in both groups (0.06 vs 0.04 IU/mL; p=0.2), mean endogenous thrombin potential (ETP) was significantly higher in the COVID group (1929±119.7 vs 1528±138.9 nM*min; p=0.02), although peak thrombin was similar (173.6±26 vs 161.5±31nM). ETP-TM ratio was similar between groups (0.3±0.1 vs 0.2±0.1; p=0.3).Despite increased ETP, the lag time to thrombin generation was significantly prolonged in the COVID group (8.3±0.6 vs 5.8±0.5 mins, p= 0.006). This pattern has previously been observed in vascular diseases associated with altered plasma tissue factor pathway inhibitor (TFPI) activity. In the presence of an anti-TFPI antibody, the difference in lagtime between groups was attenuated (4.7±0.2 vs 3.5±0.1 mins; p= 0.002) and the difference in overall thrombin generation (delta TG) between both groups became significantly increased (Fig.1).ConclusionPlasma thrombin generation is enhanced in patients with non-severe COVID-19 despite pharmacological thromboprophylaxis. Endothelial dysfunction is also observed in this group and appears to modulate parameters of plasma thrombin generation. The clinical implications of these observations are not known although clinical studies of intensified thromboprophylaxis in attenuating thrombotic risk and other complications are ongoing.Fig 1. Inhibition of TFPI activity enhances thrombin generation in COVID-19.In the presence of an inhibitory anti-TFPI antibody, peak plasma thrombin generation was enhanced in COVID-19 in contrast to that observed among SARS-CoV-2 PCR negative hospitalised patients (339.6+25.2 vs 247.4+10.1, p=0.01). [Display omitted] DisclosuresMaguire: Actelion: Research Funding; Bayer Pharma: Research Funding. Ni Ainle: Daiichi-Sankyo: Research Funding; Actelion: Research Funding; Leo Pharma: Research Funding; Bayer Pharma: Research Funding. Kevane: Leo Pharma: Research Funding.