Antithrombin Levels Research Articles

Characterization and Hemocompatibility of α, β, and γ Cyclodextrin-Modified Magnetic Nano-Adsorbents

Kidney dysfunction leads to the retention of metabolites within the blood that are not effectively cleared with conventional hemodialysis. Magnetic nanoparticle (MNP)-based absorbents have inherent properties that make them amenable to capturing toxins in the blood, notably a large surface area that can be chemically modified to enhance toxin capture and the ability to be easily collected from the blood using an external magnetic field. Cyclodextrins (CDs) present a chemical structure that facilitates the binding of small molecules. However, the hemocompatibility of MNPs modified with films composed of different native types of CDs (α, β, or γ) has not yet been investigated, which is information crucial to the potential clinical application of MNPs to supplement hemodialysis. To this end, films of α-, β-, or γ-CDs were formed on MNPs and characterized. The impact of these films on the adsorbed protein structure, composition of key adsorbed proteins, and clotting kinetics were evaluated. It was found that modified MNPs did not significantly affect the secondary structure of some proteins (albumin, lysozyme, α-lactalbumin). The adsorbed proteome from platelet-poor human plasma was evaluated as a function of film properties. Compared to non-modified nanoparticles, CD-modified MNPs exhibited a significant decrease in the adsorbed protein per surface area of MNPs. The immunoblot results showed variations in the adsorption levels of C3, fibrinogen, antithrombin, Factor XI, and plasminogen across CD-modified MNPs. The hemocompatibility experiments showed that CD-modified MNPs are compatible with human whole blood, with no significant impact on platelet activation, hemolysis, or hemostasis.

The effects of an aggressive breast tumor on thrombosis after antithrombin downregulation in a hypercoagulable mouse model

BackgroundDespite improvements in therapy, breast cancer still contributes to high mortality rates. Survival of these patients becomes progressively worse upon diagnosis with cancer-associated thrombosis (CAT). Unfortunately, the mechanism causing CAT has remained unclear. ObjectiveSet up an acute and non-invasive hypercoagulable mouse model with an aggressive breast cancer and study the mechanism of cancer-associated thrombosis. MethodsMice were grafted with the aggressive breast cancer cell line MDA-MB-231 or sham-treated. Subsequently, an acute imbalance in coagulation was introduced by injecting a synthetic small interfering (si) RNA targeting hepatic Serpinc1 to knockdown antithrombin – a condition known to predispose to cause a hypercoagulant state in vivo. ResultsSilencing Serpinc1 with siRNA decreased plasma antithrombin levels. siRNA treatment had no short-term effects on tumor characteristics, but increased distant metastasis within the timeframe of this study. The systemic pro-inflammatory status, with elevated platelet counts and fibrinogen levels in tumor-bearing mice, was also not affected by antithrombin silencing. While elevated fibrin deposition in the liver upon Serpinc1 targeting was not significantly affected by the presence of breast cancer, knockdown of antithrombin did significantly increase intratumoral fibrin deposition and inflammation. Surprisingly, in the presence of an aggressive tumor, a protective outcome with less clinical features coinciding with venous thrombosis were observed in mice with antithrombin knockdown. ConclusionWe conclude that the presence of a breast tumor protects hypercoagulant mice from severe consumption of coagulation factors after lowering hepatic antithrombin levels, possibly due to elevated platelet counts. However, the consequences on cancer-associated thrombosis remained inconclusive.

V-313.1: A novel anticoagulation protocol increased levels of antithrombin III, protein C and S after liver transplantation in children and resulted in a reduced incidence of hepatic artery thrombosis.

V-313.1: A novel anticoagulation protocol increased levels of antithrombin III, protein C and S after liver transplantation in children and resulted in a reduced incidence of hepatic artery thrombosis.

Acquired antithrombin deficiency in adult patients with postcardiotomy extracorporeal membrane oxygenation.

This study aimed to investigate the relationship between acquired antithrombin deficiency in patients undergoing postcardiotomy extracorporeal membrane oxygenation (PC-ECMO) and thromboembolic or haemorrhagic events such as bleeding, peripheral arterial thromboembolism, and ischemic cerebrovascular events. The study was designed as a single-center, prospective study and conducted at our hospital between November 2019 and June 2021. 50 patients who underwent ECMO due to postcardiotomy cardiogenic shock were included in the study. Antithrombin (AT) activity testing was performed immediately after ECMO placement and continued for 5 days. The total of haemorrhagic or thromboembolic events was defined as morbidity. The entire patient population was assessed daily for AT measurements according to morbidity status, and ROC analysis was applied to determine the cut-off point. The correlation between clinical outcomes and morbidities with antithrombin levels was analysed. In our study, we identified a cut-off for AT levels on the first postoperative day. The risk of both bleeding (p = .006) and thromboembolism (p = .012) was significantly higher in patients below the 48.9% cut-off value. AT levels were compared with data on separation from PC-ECMO. The rate of separation from ECMO was 7.969 times higher in cases with AT levels above 51.8 on the third postoperative day and 5.6 times higher in cases with AT levels above 47.5 on the fourth postoperative day. Acquired antithrombin deficiency may develop in adults undergoing PC-ECMO. In our study, we demonstrated that in patients with low antithrombin levels, the risk of bleeding and thromboembolism increased. Additionally, since AT levels were higher in survivors, this can be considered an indicator of severity. This study is the first prospective study related to determining target antithrombin levels in adult patients undergoing PC-ECMO.

An Investigative Study of Prothrombin Time, Activated Partial Thromboplastin Time and Antithrombin Levels in Patients with Ischaemic Stroke

Background: The haemostatic system maintains a balance between prothrombotic and antithrombotic components in the body. The role of this system in ischaemic stroke is not certain. Objective: Prothrombin time (PT) and Activated Partial Thromboplastin Time(APTT) are widely used screening tests to assess the haemostatic cascade. We sought to evaluate the relevance of these test and antithrombin (AT) levels in patients with ischaemic stroke. Methods: AT, platelet count, PT and APTT tests were carried out for 65 patients with ischaemic stroke and 65 controls with no history of stroke. Results: The mean age of stroke subjects was 60.4 ± 12.3yrs. PT and APTT in the test and control groups were similar and Antithrombin levels did not show significant difference. But there was a significant association between functional AT deficiency and diabetes mellitus in the ischaemic stroke group. A significant negative correlation existed between functional AT activity and prothrombin and between AT Ag levels and APTT Conclusion: There was no difference in the Antithrombin levels, PT and APTT values in patients with ischaemic stroke and those without a history of stroke and carrying out these tests routinely to assess hypercoagulable states in ischaemic stroke patients may not have any diagnostic value in our population.

Management of Therapeutic-intensity Unfractionated Heparin: A Narrative Review on Critical Points.

Nowadays, unfractionated heparin (UFH) use is limited to selected patient groups at high risk of both bleeding and thrombosis (patients in cardiac surgery, in intensive care unit, and patients with severe renal impairment), rendering its management extremely challenging, with many unresolved questions despite decades of use. In this narrative review, we revisit the fundamental concepts of therapeutic anticoagulation with UFH and address five key points, summarizing controversies underlying the use of UFH and discussing the few recent advances in the field: (1) laboratory tests for UFH monitoring have significant limitations; (2) therapeutic ranges are not well grounded; (3) the actual influence of antithrombin levels on UFH's anticoagulant activity is not well established; (4) the concept of UFH resistance lacks supporting data; (5) scarce data are available on UFH use beyond acute venous thromboembolism. We therefore identified key issues to be appropriately addressed in future clinical research: (1) while anti-Xa assays are often considered as the preferred option, we call for a vigorous action to improve understanding of the differences between types of anti-Xa assays and to solve the issue of the usefulness of added dextran; (2) therapeutic ranges for UFH, which were defined decades ago using reagents no longer available, have not been properly validated and need to be confirmed or reestablished; (3) UFH dose adjustment nomograms require full validation.

Differences in coagulation responses to vascular injury between uninterrupted dabigatran and apixaban: A clinical prospective randomized study

BackgroundThe coagulation response during vascular injury with uninterrupted administration of direct oral anticoagulants has not been elucidated. ObjectiveOur aim was to evaluate differences in coagulation responses after vascular injury between uninterrupted direct thrombin inhibitor and direct factor Xa inhibitor recipients. MethodsPatients scheduled for catheter ablation for atrial fibrillation were randomly assigned to receive dabigatran or apixaban in this prospective, randomized, comparative, parallel-group study. Venous blood was collected 3 times: 180 minutes after taking the anticoagulant on the day before the procedure, before vascular punctures of the ablation procedure, and 10–15 minutes after the start of vascular punctures. ResultsForty-two patients were enrolled. The prothrombin fragment 1+2 level, the primary end point, was much larger after vascular puncture in the uninterrupted dabigatran recipients (median, 83 pmol/L; interquartile range, 56–133 pmol/L) than in the uninterrupted apixaban recipients (median, 1 pmol/L; interquartile range, −3 to 19 pmol/L; P < .001). Antithrombin levels decreased after vascular puncture in dabigatran recipients, and both protein C and antithrombin levels decreased after vascular puncture in apixaban recipients. ConclusionUnlike uninterrupted apixaban, uninterrupted dabigatran does not inhibit thrombin generation in response to vascular injury.

Ramadan intermittent fasting is associated with improved anticoagulant activity among healthy people: a case–control study

Data on the pathophysiological mechanisms of hemostatic alterations in the thrombotic events that occur during Ramadan intermittent fasting (RIF), particularly in the natural coagulation inhibitors, are very limited. Thus, our objective was to evaluate the effect of RIF on the natural anticoagulants level, antithrombin, protein C, and total and free protein S (PS) in healthy participants. Participants were divided into two groups. Group I consisted of 29 healthy fasting participants whose blood samples were taken after 20 days of fasting. Group II included 40 healthy non-fasting participants whose blood samples were taken 2–4 weeks before the month of Ramadan. Coagulation screening tests including prothrombin time (PT), activated partial thromboplastin time (APTT) and plasma fibrinogen level, natural anticoagulants; antithrombin, protein C, free and total PS and C4 binding protein (C4BP) levels were evaluated in the two groups. High levels of total and free PS without change in antithrombin, protein C, and C4BP levels were noted in the fasting group as compared with non-fasting ones (p < 0.05). PT and APTT showed no difference between the two groups. However, the fibrinogen level was higher in the fasting group. In conclusion, RIF was found to be associated with improved anticoagulant activity in healthy participants, which may provide temporal physiological protection against the development of thrombosis in healthy fasting people.

Clinical significance for assessing adaptive hemostasis changes during multiple pregnancy after in vitro fertilization

Aim: to assess adaptive hemostasis changes in multiple dichorionic pregnancy after in vitro fertilization (IVF). Materials and Methods. A prospective observational randomized controlled trial was conducted by examining 58 and 46 pregnant women with multiple dichorionic diamniotic twins resulting from applying assisted reproductive technologies (ART) and spontaneous delivery (comparison group), respectively. Hemostasis parameters were studied as follows: activated partial thromboplastin time (APTT), prothrombin time (PT), thrombin time (TT), fibrinogen, antithrombin, protein C, protein S, functions of protein С (РrоС Global test), D-dimer, platelet aggregation with adenosine-5-diphosphate (ADP), ristocetin, and collagen. Results. A high coagulation potential was revealed, more prominent after using ART (p &lt; 0.05). Fibrinogen level gradually increased while gestation age increased, whereas APTT, PT and TT level decreased. In the group with natural conception, fibrinogen increased by 22 % in the second trimester, reaching 4.5 g/L (95 % CI = 4,2–4,8) and by 6 % in the third trimester, reaching 4.8 g/L (95 % CI = 4,3–5,4), whereas in the IVF group – by 26 %, reaching 5.3 g/L (95 % CI = 4,7–5,6) and by 21 %, reaching (6.5 g/L; 95 % CI = 5,2–6,8) in relevant trimester of pregnancy, respectively. Antithrombin level was lower in IVF patients – 76.8 % (95 % CI = 72.6 – 81.0) in the second trimester, reaching 70.6 % (95 % CI = 64.8–76.4) in the third trimester (p &lt; 0.001). Protein C level did not differ significantly between groups and was low within the reference range. The aggregatogram demonstrated a high platelet hemostatic potential in IVF patients (p &lt; 0.05) as early as in the first trimester: ADP-induced aggregation – 68.3 % (95 % CI = 62.9–73.7), ristocetin-induced aggregation – 53.1 % (95 % = CI 48.7–58.5), collagen-induced aggregation – 58.4 % (95 % CI = 52.1–64.7). In the third trimester, both platelet aggregation and functional activity (ADP-induced aggregation – 64.5 % [95 % CI = 59.3–69.7], ristocetin-induced aggregation – 68.4 % [95 % CI = 63.2–73.6], collagen-induced aggregation – 50.7 % [95 % CI = 44.3–57.1]; p &lt; 0.05) and D-dimer level persistently increased, also more prominently in the IVF group (1.60 ± 0.46 ng/ml; p &lt; 0.05). Conclusion. Gestational adaptation in induced multiple pregnancies is at high risk of breach in compensatory mechanisms and requires monitoring for timely detection of decompensation signs and their correction to prolong pregnancy till optimal delivery time frame.

Thrombin Generation Profile Using ST-Genesia after PEG-asparaginase in Pediatric Patients with Acute Lymphoblastic Leukemia.

Venous thromboembolism (VTE) etiology in children with acute lymphoblastic leukemia (ALL) is multifactorial. The use of global assays of hemostasis as a thrombin generation test (TGT) is useful to individualize VTE risk in adult patients. This prospective cohort study aimed to evaluate the usefulness of an automated TGT to evaluate VTE risk during ALL treatment in children. TGT (automated analyzer ST Genesia; ThromboScreen) and pro- and anticoagulant plasma proteins were analyzed during ALL treatment in pediatric patients following LAL-SEHOP-PETHEMA-2013 guidelines. Results were compared with a series of pediatric normal controls and evaluated according to pegylated asparaginase PEG-ASP administration and to VTE risk factors. The study included 67 patients: males n = 35, B-ALL (n = 60). None had a VTE during the evaluated period. Compared to healthy controls, the normalized endogenous thrombin potential (N-ETP) ratio in patients was higher and ETP inhibition (ETP-inh) was lower, especially after PEG-ASP administration. Plasmatic protein C and protein S levels decreased after PEG-ASP administration, but antithrombin mean level did not. A bivariant analysis showed that ETP-inh was lower in patients >10 years old (p = 0.05) and in those with non-O blood type (p = 0.005). A linear mixed model also showed a higher TGT prothrombotic profile in patients with inherited thrombophilia. TGT could be a biomarker of a high VTE risk in ALL pediatric patients. Non-O blood group and inherited thrombophilia were associated with a significantly higher thrombotic profile, and an increased profile was also observed after administration of PEG-ASP.

Testosterone therapy does not affect coagulation in male hypogonadism: a longitudinal study based on thrombin generation.

Testosterone therapy has been variably associated with increased thrombotic risk but investigations of global coagulation in this setting are lacking. To compare global coagulation of hypogonadal men before (T0) and 6 months after (T1) starting testosterone replacement therapy (TRT), and healthy controls. Observational prospective cohort study. Two tertiary endocrinological ambulatory care centers. Thirty-eight men with hypogonadism (mean age 55, SD 13) and 38 age-matched healthy controls. Thrombin generation assay (TGA) was performed at T0 and T1 in hypogonadal men and in controls. TGA is an in vitro procedure based on the continuous registration of thrombin generation and decay under conditions mimicking the process that occurs in vivo. The following TGA parameters were recorded: lag-time; thrombin-peak concentration; time-to-reach the peak, velocity index and endogenous thrombin potential (ETP), the latter representing the total amount of thrombin generated under the driving forces of procoagulants opposed by the anticoagulants. PC, antithrombin, factor (F)VIII, and fibrinogen were assessed. No changes of TGA parameters were observed between T0 and T1. Hypogonadal men displayed significantly higher ETP, fibrinogen, and significantly lower antithrombin levels both at T0 and T1 compared to controls. Thrombin-peak of hypogonadal men was significantly higher than controls at T0 but not at T1. ETP and antithrombin were correlated with testosterone levels. Hypogonadal men display a procoagulant imbalance detected by increased thrombin generation. Short-term TRT does not worsen global coagulation, suggesting that the treatment can be safely prescribed to men diagnosed with hypogonadism.

Clinical outcomes of antithrombin III supplementation in an overt disseminated intravascular coagulation: a longitudinal single-institutional experience and retrospective analysis.

Antithrombin is a small plasma glycoprotein synthesized in the liver that belongs to the serpin family of serine protease inhibitors and inactivates several enzymes in the coagulation pathway. It plays a leading major factor on coagulation pathway, therefore administration of antithrombin is essential to treat serious clinical conditions such as disseminated intravascular coagulation (DIC). Despite the theoretical benefits of antithrombin supplementation, the optimal antithrombin activity for heparin efficacy and the benefits of antithrombin supplementation in various disease entities are not yet fully understood. The strict administration guidelines on antithrombin III in cases of DIC by the National Health Insurance Service and the Ministry of Food and Drug Safety complied as follows: antithrombin levels below 20 mg/dL in adults; antithrombin activity below 70% of normal in adults; total administration period of antithrombin must be carefully limited to within maximum 3 days, and the total administration dose must be below 7,000 international unit (IU), (loading dose, 1,000 IU in 1 hour: maintenance dose, 500 IU every 6 hours for 3 days). We identified 76 eligible for analysis according to the above-mentioned criteria in our institution (male/female, 59/17). Forty-four were identified to the non-survivor group and 32 patients were recognized as the survivor group. The baseline parameters in the non-survivor and survivor groups were comparable with no significant differences in age (66.5±18.1 vs. 66.0±16.2 years, P=0.90), sex (32/12 vs. 27/5, P=0.35), hospital length of stay (31.1±34.5 vs. 31.2±26.1 days, P=0.99), sequential organ failure assessment (SOFA) (7.3±2.5 vs. 6.6±2.0, P=0.22), simplified acute physiology score II (SAPS II) (46.0±8.8 vs. 43.5±9.2, P=0.23), cause for DIC (P=0.95), and underlying disease (P=0.38). The levels of antithrombin III on the day just before the administration significantly lower in the non-survivor groups than in the survivor groups (50.1%±13.6% vs. 57.6%±12.5%, P=0.01). The hemoglobin level in the 2nd day and 7th day after antithrombin III administration was significantly different between the non-survivor and survivor groups (9.9±1.9 vs. 11.0±2.0 g/dL, P=0.01, and 9.4±1.8 vs. 10.5±1.6 g/dL, P=0.006). The antithrombin III levels on the day of administration [area under the curve (AUC) =0.672] demonstrated significantly better prediction of mortality than the A antithrombin III levels on 1st day (AUC =0.552), the 2nd day (AUC =0.624), and 7th day (AUC =0.593). Our study suggests that the antithrombin administration may be effective tools for DIC treatment, and may be more positively considered, especially in the cases of DIC, which is a frequent complication of septic shock, sepsis, and other critical disease entities and which is associated with a high level of mortality. Furthermore, our study also suggests that the total doses and periods of antithrombin administration, which recommended by national guidelines, may be insufficient, therefore prolongation of period and increase of total dose of antithrombin supplement might be necessary.

Activity of protein C, protein S and antithrombin 3 in COVID-19 patients treated with different modalities of oxygen supplementation

Abstract Objectives COVID-19 in it is more severe form is characterized by a hyperinflammatory condition, hypercoagulation state and the appearance of pulmonary microembolism. In this study we wanted to correlate levels of D-Dimer, protein C, protein S and antithrombin 3 with severity of disease and clinical outcome. Methods We included 134 of patients who were divided in 3 groups regarding oxygen support (high flow oxygen therapy, mechanical ventilation and oxygen supplementation with nasal cannula or mask). Results Concentration of D-Dimer, and activity of protein C and antithrombin 3 are presented as mean±SD and differed significantly between patients on mechanical ventilation (3.26 ± 1.15 mg/L, 86 ± 22.55 %, 81.21 ± 17.61 %)/HFNO (2.35 ± 1.68 mg/L, 109.6 ± 26.96 %, 94.67 ± 17.49 %)/BNC (1.37 ± 1.17 mg/L, 116.92 ± 28.16 %, 103.29 ± 15.63 %) with p&lt;0.001 for all parameters. Mortality in oxygen group was 10.9 %, in HFNC group 40.7 % and in mechanical ventilated group 80 %. Conclusions determination of anticoagulant factors in COVID-19 patients may indicate which of them are at increased risk of developing severe disease, venous thromboembolism and fatal clinical outcome.

Impact of Thrombophilic Polymorphisms in Antenatal Women on Perinatal Health: A Single-Center Prospective Study.

Despite pregnancy's hypercoagulable state, the correlation between inherited thrombophilia and thrombotic adverse pregnancy outcomes remains uncertain. The objective of this study was to determine the prevalence of inherited thrombophilic polymorphisms among asymptomatic pregnant individuals and to examine their potential correlation with adverse perinatal outcomes. in this single-center prospective study, 105 healthy pregnant women were included. Genotyping was conducted for factor V Leiden (FVL), prothrombin gene mutation, methylenetetrahydrofolate reductase enzyme (MTHFR) C677T, MTHFR A1298C, and plasminogen activator inhibitor-1 (PAI-1), alongside the assessment of protein C (PC), protein S (PS), and antithrombin (AT) levels. The study analyzed the association between inherited thrombophilic polymorphisms and pregnancy complications linked to placental insufficiency, such as gestational hypertension (GH), preeclampsia (PE), intrauterine death (IUD), fetal growth restriction (FGR), and placental abruption. The prevalence of identifiable thrombophilic polymorphism mutations was 61.9% (95% confidence interval-CI 52.4-70.8%), with the most common single mutation being PAI-1 4G/5G (12/105, 11.4%, 95% CI 6.4-18.5). The most frequent combined mutation was heterozygosity for MTHFR C677T and PAI-1 (12/105, 11.4%, 95% CI 6.4-18.5). Notably, no FVL homozygous carriers or single homozygous and heterozygous carriers for prothrombin polymorphisms were found. Additionally, no deficiencies in PC and AT were detected among participants. Except for homozygosity for PAI-1, none of the studied polymorphisms demonstrated a significant association with pregnancy complications linked to placental insufficiency. The asymptomatic carriers of inherited thrombophilic polymorphisms do not have an increased risk of adverse perinatal outcomes.

Fitusiran reduces bleeding in factor X–deficient mice

AbstractFactor X (FX) deficiency is a rare bleeding disorder manifesting a bleeding tendency caused by low FX activity levels. We aim to explore the use of fitusiran (an investigational small interfering RNA that silences antithrombin expression) to increase thrombin generation and the in vivo hemostatic potential under conditions of FX deficiency. We therefore developed a novel model of inducible FX deficiency, generating mice expressing <1% FX activity and antigen (f10low mice). Compared with control f10WT mice, f10low mice had sixfold and fourfold prolonged clotting times in prothrombin time and activated partial prothrombin time assays, respectively (P < .001). Thrombin generation was severely reduced, irrespective of whether tissue factor or factor XIa was used as an initiator. In vivo analysis revealed near-absent thrombus formation in a laser-induced vessel injury model. Furthermore, in 2 distinct bleeding models, f10low mice displayed an increased bleeding tendency compared with f10WT mice. In the tail-clip assay, blood loss was increased from 12 ± 16 μL to 590 ± 335 μL (P < .0001). In the saphenous vein puncture (SVP) model, the number of clots generated was reduced from 19 ± 5 clots every 30 minutes for f10WT mice to 2 ± 2 clots every 30 minutes (P < .0001) for f10low mice. In both models, bleeding was corrected upon infusion of purified FX. Treatment of f10low mice with fitusiran (2 × 10 mg/kg at 1 week interval) resulted in 17 ± 6% residual antithrombin activity and increased thrombin generation (fourfold and twofold to threefold increase in endogenous thrombin potential and thrombin peak, respectively). In the SVP model, the number of clots was increased to 8 ± 6 clots every 30 minutes (P = .0029). Altogether, we demonstrate that reduction in antithrombin levels is associated with improved hemostatic activity under conditions of FX deficiency.

Prothrombin conversion and thrombin decay in patients with cirrhosis—role of prothrombin and antithrombin deficiencies

BackgroundThrombin generation (TG) in the presence of thrombomodulin (TG-TM) in the plasma of patients with cirrhosis (PWC) is tilted toward a hypercoagulable phenotype. Low protein C and elevated factor VIII levels play a role, but other determinants, such as the prothrombin/antithrombin pair, must also be studied. ObjectivesThe objectives were (i) to quantitatively assess the subprocesses (prothrombin conversion and thrombin decay) and (ii) to understand the underlying mechanism by studying TG dynamics after prothrombin and antithrombin plasma level correction in PWC. MethodsWe studied TG-TM in plasma samples of 36 healthy controls (HCs) and 41 PWC with prothrombin and antithrombin levels of <70% and after their correction. We initiated coagulation with an intermediate picomolar concentration of tissue factor. We determined the overall thrombin potential, prothrombin conversion, and thrombin decay. ResultsTG-TM was increased in PWC compared with HC due to impaired thrombin inhibition. Indeed, thrombin decay capacity (min−1) decreased from 0.37 (0.35-0.40) in HC to 0.33 (0.30-0.37) in the Child–Turcotte–Pugh A (CTP-A; P = .09), 0.27 (0.26-0.30) in the CTP-B (P < .001), and 0.20 (0.19-0.20) in the CTP-C (P < .001) group. Concomitant correction of prothrombin and antithrombin increased endogenous thrombin potential with prothrombin conversion surpassing thrombin decay. By contrast, when we corrected only antithrombin, TG-TM was normalized and even consistent with a hypocoagulable phenotype in the CTP-C group. ConclusionOur results highlight that in PWC, hypercoagulability (evidenced in the presence of TM) is due to impaired thrombin decay, whereas low prothrombin levels do not translate into decreased prothrombin conversion, likely due to altered TM-activated protein C negative feedback.

Antithrombin Levels and Heparin Responsiveness during Venoarterial Extracorporeal Membrane Oxygenation: A Prospective Single-center Cohort Study.

Unfractionated heparin, administered during venoarterial extracorporeal membrane oxygenation to prevent thromboembolic events, largely depends on plasma antithrombin for its antithrombotic effects. Decreased heparin responsiveness seems frequent on extracorporeal membrane oxygenation; however, its association with acquired antithrombin deficiency is poorly understood. The objective of this study was to describe longitudinal changes in plasma antithrombin levels during extracorporeal membrane oxygenation support and evaluate the association between antithrombin levels and heparin responsiveness. The hypothesis was that extracorporeal membrane oxygenation support would be associated with acquired antithrombin deficiency and related decreased heparin responsiveness. Adults receiving venoarterial extracorporeal membrane oxygenation were prospectively included. All patients received continuous intravenous unfractionated heparin using a standardized protocol (target anti-Xa 0.3 to 0.5 IU/ml). For each patient, arterial blood was withdrawn into citrate-containing tubes at 11 time points (from hour 0 up to day 7). Anti-Xa (without dextran or antithrombin added) and antithrombin levels were measured. The primary outcome was the antithrombin plasma level. In the absence of consensus, antithrombin deficiency was defined as a time-weighted average of antithrombin less than or equal to 70%. Data regarding clinical management and heparin dosage were collected. Fifty patients, including 42% postcardiotomy, were included between April 2020 and May 2021, with a total of 447 samples. Median extracorporeal membrane oxygenation duration was 7 (interquartile range, 4 to 12) days. Median antithrombin level was 48% (37 to 60%) at baseline. Antithrombin levels significantly increased throughout the follow-up. Time-weighted average of antithrombin levels was 63% (57 to 73%) and was less than or equal to 70% in 32 (64%) of patients. Overall, 45 (90%) patients had at least one antithrombin value less than 70%, and 35 (70%) had at least one antithrombin value less than 50%. Antithrombin levels were not significantly associated with heparin responsiveness evaluated by anti-Xa assay or heparin dosage. Venoarterial extracorporeal membrane oxygenation support was associated with a moderate acquired antithrombin deficiency, mainly during the first 72 h, that did not correlate with heparin responsiveness.

Neonatal purpura fulminans: A rare, life-threatening, and rapidly progressing disorder of coagulation

Background: Neonatal purpura fulminans (NPF) is a life-threatening rare disease, which can be caused by deficiencies of protein C or protein S in a congenital or acquired manner. It is characterized by thrombosis of microvasculature, peri-vascular hemorrhage, and disseminated intravascular coagulation (DIC) occurring in the neonatal period. Clinical Description: A term female baby presented at 40 h of life with multiple purpuric rashes over the left foot which over 1 day extended until the knee. Over the next 3 days, there was rapid progression to involve extensive areas of necrosis with gangrene of toes of left foot, both forearms, bilateral temporal areas, peri-orbital regions, and left ear, in addition to multiple hemorrhagic blebs. Management and Outcome: Investigations showed anemia and thrombocytopenia with normal leucocyte count. DIC was suspected (INR 2), sepsis screen was negative, and fresh frozen plasma (FFP) was transfused 8th hourly. Arterial and venous Doppler was normal and blood culture showed no growth. Suspecting NPF, protein C, protein S, and anti-thrombin levels were sent, which showed a low protein C and protein S value. Mutations involving factor V Leiden, prothrombin gene, and MTHFR gene were not detected. The baby was started on low molecular weight heparin and, FFP and platelet concentrate replacement were continued, but she succumbed to the illness. Conclusion: NPF is a rare life-threatening entity that is fatal without prompt recognition of the condition. Therefore, it is necessary to recognize it early and initiate treatment.

Anticoagulant effects of protein C, protein S, and antithrombin levels on the protein C pathway in young children.

The protein C (PC) pathway involves physiological anticoagulant factors (PC, protein S [PS], and factor V) and performs major anticoagulant functions in adults. Variations in overall PC pathway function due to dynamic changes in PC and PS in early childhood are poorly understood. We aimed to evaluate the contributions of PC pathway function during early childhood by measuring changes in plasma thrombin generation (TG) after administration of the PC activator protac. We evaluated correlations between anticoagulant factors and percentage of protac-induced coagulation inhibition (PiCi%). Before protac addition, TG in newborns (n = 35), infants (n = 42), young children (n = 35), and adults (n = 20) were 525 ± 74, 720 ± 96, 785 ± 53, and 802 ± 64mOD/min, and PiCi% were 42.1 ± 9.9, 69.8 ± 11.0, 82.9 ± 4.4, and 86.9 ± 3.4%, respectively. The distribution of PiCi% on the two axes of TG (with or without protac) changed continuously with age and differed from that of warfarin-treated plasma and adult PC- or PS-deficient plasma. PiCi% increased dynamically during infancy and correlated with PS levels in newborns and PC levels in young children. Addition of PC or fresh frozen plasma equivalent to approximately 25% PC to PC-deficient plasma improved PiCi%. This automatic measurement requires only a small sample volume and is useful for analysis of developmental hemostasis.

Predikcija serumskog neuritina i neuron-specifične enolaze za prognozu kod pacijenata sa traumatskom povredom mozga u kombinaciji sa povredom kičmene moždine

Background: Serum neuritin and neuron-specific enolase (NSE) have predictive value for the prognosis of patients with combined traumatic brain injury (TBI) and spinal cord injury (SCI). Studying their predictive effects has positive value for disease control and treatment. Methods: Sixty patients with combined TBI and SCI were recruited and rolled into three groups according to prognosis: Group I (n=42, favourable prognosis), Group II (n=11, poor prognosis), and Group III (n=7, death). Clinical indicators were compared between the groups, and the predictive value of different indicators for prognosis was analyzed. Results: The proportion of patients with combined injuries to other organs and hypotension, as well as levels of platelets (PLT), D-dimer (D-D), antithrombin III (AT-III), S100 protein (S100 ), NSE, and serum neurofilament levels were significantly higher in Groups II and III compared to Group I. Conversely, the Glasgow Coma Scale (GCS) scores were significantly lower in Group I (P&lt;0.05). Multivariable logistic regression analysis revealed that other organ injuries, GCS score, PLT, D-D, and AT-III significantly influenced the prognosis of TBI combined with SCI patients (P&lt;0.05), while hypotension, NSE, serum neurofilament levels, S100 , and accompanying organ injuries were highly correlated with the prognosis of TBI combined with SCI patients (P&lt;0.001). The predictive sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of NSE combined with serum neurofilament in predicting the prognosis of TBI combined with SCI patients were significantly higher than the singular predictive efficacy of NSE or serum neurofilament alone (P&lt;0.05). Conclusions: To evaluate the prognosis of TBI combined with SCI patients, consideration should be given to factors such as other organ injuries, hypotension, consciousness assessment, and levels of various biomarkers. Furthermore, combined testing of serum neurofilament and NSE can more accurately predict the prognosis of TBI combined with SCI patients.