Extrinsic Coagulation Pathway Research Articles

The first report on coagulation and phospholipase A2 activities of Persian Gulf lionfish, Pterois russelli, an Iranian venomous fish

Pterois russelli is a venomous fish belonging to scorpionidae family. Regarding to high significance value for tracing potential therapeutic molecules and special agents from venomous marine creatures, the present study was aimed to characterization of the Persian Gulf lionfish venom.Proteolytic, phospholipase, hemolytic, coagulation, edematogenic and dermonecrotic activities were determined for extracted venom. The LD50 of P. russelli venom was determined by intravenous injection in white Balb/c mice.Phospholipase A2 activity was recorded at 20 μg of total venom. Coagulation activity on human plasma was shown by Prothrombin Time (PT) and activated Partial Thromboplastin Time (APTT) assays and coagulation visualized after 7 and 14 s respectively for 60 μg of crude venom. LD50 was calculated as 10.5 mg/kg. SDS-PAGE revealed the presence of major and minor protein bands between 6 and 205 kDa. Different amounts of crude venom ranged from 1.87 to 30 μg showed proteolytic activity on casein. The highest edematic activity was detected at 20 μg. Our findings showed that the edematic activity was dose dependent and persisted for 48 h after injection. The crude venom did not induce dermonecrotic activity on rabbit skin and showed no hemolytic activity on human, mouse and rabbit erythrocytes.This is the first report for phospholipase A2 and coagulation activity in venomous fish and venomous marine animals respectively. Proteolytic activity of P. russelli venom is in accordance with the other genara of scorpionidae family. According to venom activity on intrinsic and extrinsic coagulation pathways, lionfish venom would be contained an interesting pharmaceutical agent. This study is pending to further characterization of phospholipase A2, coagulation, and protease activities and also in vivo activity on animal model of surface and internal bleeding.

Sodium Bicarbonate Facilitates Hemostasis in the Presence of Cerebrospinal Fluid Through Amplification of Platelet Aggregation.

Appropriate hemostasis is essential for clear visualization of the neural structures and cleavage planes. It is also essential for avoiding heat-induced injury, minimizing blood loss, and reducing operative time. To determine the role of cerebrospinal fluid (CSF) in platelet-dependent hemostasis during neurosurgery. The amplification of aggregation, activation of integrin αIIbβ3, intrinsic and extrinsic coagulation pathways, and activation of signaling cascades in platelets were evaluated. For comparison, various concentrations of a commercially available artificial CSF solution (aCSF), an artificial CSF solution prepared by the authors, and normal saline (NS) were used. Differences between aCSF and NS in obtaining in vivo hemostasis were assessed by measuring the tail vein bleeding time in C57BL/6N mice. Platelet aggregation was directly amplified by the addition of aCSF through increased activation of integrin αIIbβ3, phosphatidylserine exposure, and P-selectin expression. However, the prothrombin time and activated partial thromboplastin time were not primarily related to coagulation activity with the addition of aCSF. Activation of Src kinase was related to platelet activation by aCSF. The elimination of sodium bicarbonate from aCSF and the addition of the selective inhibitor of the HCO3/Cl exchanger, 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid disodium salt, significantly inhibited platelet aggregation. The bleeding time in aCSF-treated mice was significantly shorter than that in NS-treated mice. Sodium bicarbonate facilitates hemostasis through the amplification of platelet aggregation function. The existence of CSF and irrigation with aCSF provide better conditions for physiological hemostasis and they have the potential of improving hemostasis by bipolar coagulation or with irrigation during neuroendoscopic procedures.

Pathogenesis of Crimean–Congo Hemorrhagic Fever From an Immunological Perspective

Crimean–Congo hemorrhagic fever (CCHF) is a severe viral infection disease. Infection is a battle between the virus and host immune system. The CCHF virus can enter to the organism by way of skin, mucosa, or inhalation and encounters innate immune system cells like monocytes, macrophages, and dendritic cells. These cells cannot successfully eliminate viruses. Thus, the viruses are able to disseminate to regional lymph nodes and to whole body. Different viral pathogen-associated molecular patterns (PAMPs) stimulate the intracellular Toll-like receptors, RIG-like Helicase receptors, and NOD-like receptors. So, different inflammatory cytokines, chemokines, and adhesion molecules are induced. The virus has both direct cytopathic effects on parenchymal cells especially on the liver, spleen, and endothelial cells and non-cytopathic indirect effects depending upon releasing factors from innate immune cells. In severe fatal cases, infection causes coagulation by stimulating both intrinsic and extrinsic coagulation pathways and disseminated intravascular coagulopathy occurs. The prognosis of the disease is dependent on the balance between the viral load and host’s immune system. While high values of IL-12/IL-10, IL-15/IL-10, IL-18/IL-10, and IFN-γ/IL-10 ratios show strong TH1 immune status, low values show suppressed immune system. These ratios together with viral load can indicate the patients’ clinical prognosis from an immunological perspective.

The Impact of Chronic Smoking on the Intrinsic and Extrinsic Coagulation Pathways of Smokers in Enugu, South-East Nigeria

The Impact of Chronic Smoking on the Intrinsic and Extrinsic Coagulation Pathways of Smokers in Enugu, South-East Nigeria

Effects of glycosaminoglycan from Mactra veneriformis on the protein C system and expression of relevant factors in human umbilical vein endothelial cells.

The aim of this study was to examine whether glycosaminoglycan (GAG) from Mactra veneriformis had an impact on the protein C (PC) system in rats and expression of relevant factors in human umbilical vein endothelial cells. Isotonic saline, heparin sodium (4 mg/kg), and GAG (1, 4, and 16 mg/kg) were administered to Wistar rats through caudal vein at the total volume of 0.5 ml for each injection, and the anticoagulant blood was prepared. The activities of PC and protein S, and the concentrations of activated protein C inhibitor (APCI) and thrombomodulin were detected according to the kit instructions. The expression levels of tissue factor, tissue factor pathway inhibitor and thrombomodulin genes in human umbilical vein endothelial cells were detected by the reverse transcription polymerase chain reaction method. GAG could significantly reduce the activity of PC (P < 0.05, P < 0.01) and slightly increase the concentration of APCI, and high concentration of GAG could significantly decrease the activity of protein S (P < 0.05) and significantly increase the concentration of thrombomodulin (P < 0.05). GAG could significantly downregulate the expression level of tissue factor gene (P < 0.05, P < 0.01) and significantly upregulate the expression levels of tissue factor pathway inhibitor and thrombomodulin genes (P < 0.05, P < 0.01). GAG showed the inhibitory effect on PC system in vivo. GAG might play an important role in the resistance to extrinsic coagulation pathway.

Role of exosite binding modulators in the inhibition of Fxa by TFPI.

Tissue factor pathway inhibitor (TFPI) down-regulates the extrinsic coagulation pathway by inhibiting FXa and FVIIa. Both TFPI and FXa interact with several plasma proteins (e. g. prothrombin, FV/FVa, protein S) and non-proteinaceous compounds (e. g. phospholipids, heparin). It was our aim to investigate effects of ligands that bind to FXa and TFPI on FXa inhibition by full-length TFPI (designated TFPI) and truncated TFPI (TFPI1-150). Inhibition of FXa by TFPI and TFPI1-150 and effects of phospholipids, heparin, prothrombin, FV, FVa, and protein S thereon was quantified from progress curves of conversion of the FXa-specific chromogenic substrate CS11-(65). Low concentrations negatively charged phospholipids (~10 µM) already maximally stimulated (up to 5- to 6-fold) FXa inhibition by TFPI. Unfractionated heparin at concentrations (0.2-1 U/ml) enhanced FXa inhibition by TFPI ~8-fold, but impaired inhibition at concentrations > 1 U/ml. Physiological protein S and FV concentrations both enhanced FXa inhibition by TFPI 2- to 3-fold. In contrast, thrombin-activated FV (FVa) impaired the ability of TFPI to inhibit FXa. FXa inhibition by TFPI1-150 was not affected by FV, FVa, protein S, phospholipids and heparin. TFPI potently inhibited FXa-catalysed prothrombin activation in the absence of FVa, but hardly inhibited prothrombin activation in the presence of thrombin-activated FVa. In conclusion, physiological concentrations TFPI (0.25-0.5 nM TFPI) inhibit FXa with a t1/2 between 3-15 minutes. Direct FXa inhibition by TFPI is modulated by physiological concentrations prothrombin, FV, FVa, protein S, phospholipids and heparin indicating the importance of these modulators for the in vivo anticoagulant activity of TFPI.

A Fever in Acute Aortic Dissection is Caused by Endogenous Mediators that Influence the Extrinsic Coagulation Pathway and Do Not Elevate Procalcitonin.

Objective A fever is observed in approximately one-third of cases of acute aortic dissection (AAD); however, the causes remain unclear. We investigated the mechanism of a fever in AAD by measuring the serum concentrations of inflammatory markers, mediators of coagulation and fibrinolysis, and procalcitonin, a marker of bacterial infection. Methods We retrospectively studied 43 patients with medically treated AAD without apparent infection. Patients were divided into those with (Group A; n=19) and without (Group B; n=24) a maximum body temperature >38°C. We established which patients fulfilled the criteria for systemic inflammatory response syndrome (SIRS), and its relationship with a fever was examined. Mediators of inflammation, coagulation and fibrinolysis were compared by a univariate analysis. Factors independently associated with a fever were established by a multivariate analysis. Results The criteria for SIRS were fulfilled in a greater proportion of patients in Group A (79%) than in Group B (42%, p=0.001). There was no difference in the procalcitonin concentration between Groups A and B (0.15±0.17 ng/mL vs. 0.11±0.12 ng/mL, respectively; p=0.572). Serum procalcitonin concentrations lay within the normal range in all patients in whom it was measured, which showed that the fever was caused by endogenous mediators. On the multivariate analysis, there was a borderline significant relationship between a fever and the prothrombin time-International Normalized Ratio (p=0.065), likely reflecting the extrinsic pathway activity initiated by tissue factor. Conclusion Our findings suggest that a fever in AAD could be caused by SIRS, provoked by endogenous mediators that influence the extrinsic coagulation pathway without elevating the serum procalcitonin concentration.

Leukocyte XII Regulates Venous Thrombosis Risk

Introduction: Previous studies show that Factor XII (XII) participates in the inflammatory response. XII regulates the expression of monocyte FcγII receptor and stimulates monocytes and macrophages to release interleukin (IL)-1 and IL-6. XII deficient patients have reduced leukocyte migration into skin windows. In vitro, purified XIIa corrects neutrophil aggregation and degranulation defects in XII-deficient plasma. Recent studies show that leukocytes initiate and propagate venous thrombosis in vivo. We examined the contribution of XII in the inflammatory response and venous thrombosis.Methods & Results: Sterile punch biopsy wounds were created on wild type (WT) and F12-/- mice. On Days 2 and 5, there was a ~3-fold decrease in CD11b-stained cells in F12-/- woundsvs. WT. On the thioglycolate (TG)-induced sterile peritonitis assay, lavage fluid from F12-/- mice contained significantly less peritoneal exudative cells (PEC)] on days 1 and 7, (p<0.008). To determine the contribution of XII in WBC function, we used XII siRNA (Alnylam Pharmaceuticals) to create plasma XII deficiency in WT mice. After tail vein injection, plasma XII was reduced to < 5% within 24 h (T1/2 plasma XII: 6.7 h). In the TG assay, even though plasma XII is decreased to less than 5%, PEC migration is the same as in WT mice. These data suggest that the reduced leukocyte migration observed in F12-/- mice is related to altered leukocyte function. On adoptive bone marrow (BM) transplantation (BMT) experiments, WT BM transplanted into KO hosts corrects the leukocyte migration defect on the TG assay. These data suggest that there is a pool of XII associated with BM cells that is functionally distinct than plasma-derived, hepatic XII. F12 cDNA is found in leukocytes and shares sequence homology to hepatic XII. Immunofluorescence confirms XII antigen on murine BM-derived and human peripheral blood WBCs. No XII antigen is observed in BM-derived leukocytes from F12-/- mice. When WBC are activated with fMLF, XII antigen translocates to the external membrane. F12-/- PMNs have reduced chemotaxis to fMLF and adherence to several integrin-binding glycoproteins. pAktS473 mediates neutrophil cell migration, integrin activation, and cytoskeletal assembly. Normal and F12-/- PMNs exhibit pAktS473 in response to fMLF and XII. Histologically, F12-/- wounds show a smaller wound gap and a greater percentage of wound re-epithelialization than WT controls. Inferior vena cava (IVC) thrombosis induced by 90% restriction to flow at 24h contains a smaller thrombus in F12-/- than WT mice (p<0.04). Histologically, IVC thrombi from WT mice contain abundant neutrophils that are adherent to the wall and trapped within a dense fibrin network (Fig 1). siRNA treatment results in less-occlusive thrombi (n.s) with an adequate neutrophil content but a finer fibrin network (Fig 1). F12-/- thrombi are non-occlusive and contain significantly less adherent neutrophils (Fig 1). XII itself is integrally a part of neutrophil extracellular traps (NETs) in the forming thrombus and F12-/- mice have reduced NETs at sites of occlusion. WT BM transplanted into F12-/- hosts corrects the thrombus weight and degree of inflammation in F12-/- mice to normal. Likewise, F12-/- BM into WT hosts, reduces thrombus weight and degree of inflammation.Conclusions: Leukocyte XII has a dual role in neutrophil function. We hypothesize that signaling by leukocyte XII contributes to neutrophil trafficking in sites of inflammation and venous stasis. At these sites, neutrophils become indispensable for activation of both the extrinsic and intrinsic pathways of coagulation during the early formation of intraluminal fibrin and for subsequent thrombus propagation by NETs and the activation of circulating XII. Defining the signaling pathway of XII in leukocytes will further our understanding as to the mechanism(s) by which these cells cooperate to initiate and propagate venous thrombosis in vivo. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Acute Efficacy of a Novel Anti-Tissue Factor Pathway Inhibitor Antibody BAY 1093884 in Hemophilia A Mouse Severe Tail Bleeding

Tissue factor pathway inhibitor (TFPI) is the major inhibitor of the tissue factor initiated extrinsic coagulation pathway in blood and is intact in patients with hemophilia. The inhibition of TFPI may restore hemostasis in patients with hemophilia. BAY 1093884 is a fully human monoclonal antibody against TFPI developed as a bypass agent for hemophilia patients with or without inhibitors. It restores thrombin burst for stable clot formation in hemophilic conditions in vitro. The goal of these studies was to determine the in vivo acute efficacy of BAY 1093884 in the hemophilia A (HemA) mouse.In the first study, the acute efficacy of BAY 1093884 (3−100 mg/kg) was demonstrated and compared with full-length recombinant factor VIII (rFVIII; 10−100 IU/kg) by a HemA mouse tail clip model, in which blood loss from a severed tail tip was measured over 45 minutes after injury (n=12−27 mice/group). Naive C57/BL6 and HemA mice were used as positive and negative controls, respectively. Whereas isotype control antibody−treated HemA mice had median blood loss of 870 μL, increasing doses of BAY 1093884 to 50 and 100 mg/kg significantly reduced blood loss to a median of 55 and 5 μL. The dose required to reduce blood loss by 50% was 18 mg/kg, approximately equivalent to the efficacy of 20 IU/kg rFVIII.In a second study, we characterized the combined action of BAY 1093884 and activated recombinant factor VII (rFVIIa; n=10−25 mice/group). Low doses of BAY 1093884 (2.5 mg/kg) and rFVIIa (0.5 and 1.0 mg/kg) with minimal efficacies were tested. Untreated HemA mice had median blood loss of 860 μL. As stand-alone treatments, 2.5 mg/kg BAY 1093884, 0.5 mg/kg rFVIIa, and 1 mg/kg rFVIIa provided minimal blood loss protection, with bleeding volume reduced to 675, 830, and 770 μL, respectively. In comparison, the combination of 2.5 mg/kg BAY 1093884 with 0.5 mg/kg rFVIIa or 1.0 mg/kg rFVIIa reduced median blood loss to 215 and 35 μL, respectively. These results showed a combination effect of BAY 1093884 and rFVIIa in this severe acute efficacy model.These studies demonstrate that BAY 1093884 could potently reduce acute blood loss in HemA mice and may offer a new treatment option for hemophilia patients. DisclosuresXu:Bayer HealthCare LLC: Employment. Koellenberger:Bayer Pharma AG: Employment. Laux:Bayer Pharma AG: Employment. Kauser:Bayer HealthCare LLC: Employment. Sim:Bayer HealthCare LLC: Employment.

Lethality of Mouse Tissue Factor Pathway Inhibitor Gene Disruption Is Rescued By Transgenic Human Tissue Factor Pathway Inhibitor Knock in

Background: Tissue factor pathway inhibitor (TFPI) is a key regulator of the extrinsic coagulation pathway. It inhibits FXa generation by forming a quaternary complex containing factor VIIa (FVIIa), tissue factor (TF), factor Xa (FXa), and TFPI. Two TFPI isoforms, TFPI alpha (TFPI a) and TFPI beta (TFPI b), have been identified, which differ in their C-terminal part due to alternative mRNA splicing events. TFPI a consists of three Kunitz domains (KD), while TFPI b contains two KDs and a C terminal GPI anchor linking the protein to endothelial cell surface. Deletion of the first Kunitz domain of TFPI, which is present in TFPI a and TFPI b in mice is known to be incompatible with viability due to intrauterine lethality (Huang et al., 1997).Aim: To generate transgenic humanized TFPI mice in which mouse (m)-TFPI is entirely replaced by human (hu)-TFPI, in order to facilitate analysis of specific anti hu-TFPI antagonists without interference from m-TFPI.Methods: Integration of the targeting vector, consisting of the m TFPI signal sequence, followed by the human TFPI cDNA and subsequent breeding analysis, was followed by genomic PCR. A sophisticated breeding strategy was used to entirely delete m-TFPI exon 4, which encodes KD1, in humanized transgenic mice. Expression of hu-/m-TFPI a and b mRNAs was analyzed by reverse transcription, cloning, and sequencing of the obtained DNA fragments. Protein levels of hu- and m-TFPI in plasma of transgenic and wild-type (wt) mice were analyzed using species specific ELISAs. Immunoprecipitation experiments in plasma and various mouse tissues are being performed to obtain more information on the presence and distribution of the hu-TFPI protein in transgenic mice.Results: Homozygous humanized TFPI mice were viable and exhibited no obvious abnormalities. Animals showed normal litter size with equal numbers of female and male pups. Genomic PCRs revealed proper integration of the targeting vector into the mouse chromosome and the homozygous status with the expected deletion of m-TFPI exon 4. Expression analyses of humanized TFPI mice on mRNA level demonstrated the absence of full length m-TFPI a and the presence of the humanized TFPI mRNA. Alternative spliced m-TFPI b messages lacking exons three and four were identified, likely leading to a nonfunctional protein. Full length hu-TFPI a mRNA was detected in various tissues in the humanized TFPI mice. The TFPI protein level in plasma from humanized mice was below the detection limit of the ELISA and at least ~300 fold below that for wt mice.Conclusion: Low levels of hu-TFPI may compensate the function of m-TFPI in vivo and circumvent embryonic lethality. Furthermore, we established a new mouse model which allows the regulation of physiologic and pathologic pathways to be assessed at TFPI plasma concentrations below the limit of detection. DisclosuresHoellriegl:Baxalta Innovations GmbH: Employment. Scheiflinger:Baxalta Innovations GmbH: Employment.

Effective tranexamic acid concentration for 95% inhibition of tissue-type plasminogen activator induced hyperfibrinolysis in children with congenital heart disease: A prospective, controlled, in-vitro study.

Although recent studies have assessed tranexamic acid (TXA) pharmacokinetics in different subgroups, the effective concentration of TXA required to completely inhibit fibrinolysis remains to be determined. An in-vitro determination of the effective TXA concentration needed for 95% inhibition (EC95) of tissue-type plasminogen activator (t-PA) activated fibrinolysis, using an experimental model designed for thromboelastometry (ROTEM). A prospective interventional study. Department of Anaesthesiology, Queen Fabiola Children's University Hospital and Laboratory of Haematology and Haemostasis, Brugmann University Hospital. Patients were enrolled between June 2013 and October 2014. Twenty children, aged between 1 and 10 years, undergoing elective cardiac catheterisation were included (10 with cyanotic and 10 with noncyanotic diseases). Exclusion criteria were child requiring a procedure in a moribund state. Ten adult volunteers were also included as controls. Citrated whole blood samples were obtained from children and volunteers. The extrinsic coagulation pathway was activated by tissue factor using the EXTEM test on ROTEM. The degree of lysis measured 30 min (LI30) after the clotting time (CT), and clot amplitudes measured at different times were recorded at baseline, after addition of 1535 units t-PA ml(-1), and following the addition of increasing TXA concentrations in t-PA activated samples. The concentration-effect analysis performed with lysis index after 30 min (LI30) allowed the determination of TXA efficacy concentration 50% (EC50), and calculation of the EC95, which was significantly lower in cardiac surgery children than in adults [8.6 μg ml(-1); 95% confidence interval (95% CI) 6.9 to 14.9 versus 11.3 μg ml(-1); 95% CI 10.6 to 12.9, P < 0.001]. In this in-vitro study, we observed that the EC95 TXA concentration that completely inhibited t-PA induced hyperfibrinolysis in children with congenital heart was significantly lower than the concentration required in healthy adult volunteers. Further studies are needed to confirm that this plasma concentration can effectively inhibit fibrinolysis activation in children undergoing cardiac surgery.

Hemostasis state, adipokine levels and markers of endothelial dysfunction in young patients with components of the metabolic syndrome

Aim. To carry out a comparative assessment of hemostasis, adipokines levels and markers of endothelial dysfunction in young patients with a variety of components of the metabolic syndrome.&#x0D; Methods. The study included 154 patients aged 18-44 years who were divided into four groups matched for age and sex: the first group - 35 patients with metabolic syndrome, the second group - 25 patients with hypertension without abdominal obesity, the third group - 22 patients with abdominal obesity without hypertension, the fourth group - 72 healthy subjects (control group). We studied the vascular-platelet, coagulation and anticoagulation units of the hemostasis system, the fibrinolytic system, the levels of adipokines and markers of endothelial dysfunction.&#x0D; Results. Patients with metabolic syndrome showed signs of activation of coagulation together with a slowdown functions of the fibrinolytic system and activation of the anticoagulation system. In young patients with hypertension without abdominal obesity increased were the levels of endothelin, plasminogen activator inhibitor type 1, angiotensin II inhibitor and extrinsic pathway of coagulation. Patients with abdominal obesity without arterial hypertension had no significant change in adipokin levels and markers of endothelial dysfunction compared to control group.&#x0D; Conclusion. In young patients with a variety of components of the metabolic syndrome revealed were signs of intravascular activation of blood coagulation in conjunction with the imbalance of adipokines levels and endothelial dysfunction.

1918 pandemic influenza virus and Streptococcus pneumoniae co-infection results in activation of coagulation and widespread pulmonary thrombosis in mice and humans.

To study bacterial co-infection following 1918 H1N1 influenza virus infection, mice were inoculated with the 1918 influenza virus, followed by Streptococcus pneumoniae (SP) 72 h later. Co-infected mice exhibited markedly more severe disease, shortened survival time and more severe lung pathology, including widespread thrombi. Transcriptional profiling revealed activation of coagulation only in co-infected mice, consistent with the extensive thrombogenesis observed. Immunohistochemistry showed extensive expression of tissue factor (F3) and prominent deposition of neutrophil elastase on endothelial and epithelial cells in co-infected mice. Lung sections of SP-positive 1918 autopsy cases showed extensive thrombi and prominent staining for F3 in alveolar macrophages, monocytes, neutrophils, endothelial and epithelial cells, in contrast to co-infection-positive 2009 pandemic H1N1 autopsy cases. This study reveals that a distinctive feature of 1918 influenza virus and SP co-infection in mice and humans is extensive expression of tissue factor and activation of the extrinsic coagulation pathway leading to widespread pulmonary thrombosis.

Découverte fortuite d’une hémophilie A mineure à l’occasion d’un purpura rhumatoïde

Henoch-Schönlein purpura is a common form of immunological vasculitis in children. Hemophilia A is a genetic disorder, inherited in a X-linked recessive pattern, and characterized by spontaneous hemorrhage or prolonged bleeding due to factor VIII deficiency. The clinical signs depend on the severity of factor VIII deficiency. We herein report the case of a 4-year-old boy admitted to the emergency room for typical rheumatoid purpura, associated with a lengthening of aPTT, whose exploration had uncovered mild hemophilia A. Laboratory assays should explore lengthening of aPTT: firstly the presence of lupus anticoagulant without bleeding risk, in an inflammatory context; secondly a deficiency of VWF and one of the factors involved in the extrinsic coagulation pathway associated with bleeding risk.

Pathogenesis of Trousseau’s syndrome

Malignancies and thrombosis have common pathogenetic features that was shown by A. Trousseau in 1865. There is now no doubt that the cancer patients occur much more frequently thromboembolism, and migratory venous thrombosis is a manifestation of paraneoplastic syndrome in cancer patients. In general, any manifestation of thrombohemorrhagic complications in cancer patients called Trousseau’s syndrome. While thrombotic complications such as venous thromboembolism are most frequent in cancer patients, may also experience severe bleeding symptoms due to systemic coagulopathies, including disseminated intravascular coagulation, haemolytic thrombotic microangiopathy, and hyperfibrinolysis. The basis of the pathophysiology of Trousseau’s syndrome, except the classic triad of Virchow, is overproduction of tissue factor (TF), the main initiator of extrinsic coagulation pathway. Thus a significant release of microparticles from tumor cells bearing tissue factor is critical not only for the formation of a blood clot, but the growth and progression of tumors. Tumor cells activate the coagulation cascade or fibrinolysis system, providing conditions for its further spread, stimulation of angiogenesis, increased vascular permeability, which in turn promotes metastasis.

Possible prevention ways of thromboembolic events in traumatology and orthopedics: experimental study

Objective - to examine coagulative and lytic activity of blood and tissues out of a blood flow with the combined anticoagulation and antioxidant therapy in the early posttraumatic period at pelvic bone fracture. Material and methods. The study was based on estimation of coagulation activity of tissues (skeletal muscles, liver, kidneys, heart and lungs) and blood at pelvic trauma while receiving anticoagulation and antioxidant therapy. All studies were performed in accordance with the federal ethical and legal standarts of investigations in experimental animals and approved by the local ethics committee. Results. It was found that anticoagulation (fraxiparine) and antioxidant (mexidol) therapy at pelvic trauma reduce the disturbances in the hemostatic system in the early posttraumatic period. Correction of hemostatic disorders was observed not only not only in the blood (organismal level), but also in the liver, kidneys, heart, lungs (the organ level). The effect of combination therapy on skeletal muscles in the area of injury was especially important - isolated use of anticoagulation therapy did not give such significant effect. Conclusion. Thus we obtained that using anticoagulant and antioxidant therapy on pelvic trauma is pathogenetically substantiated. It affected not only the intrinsic but also on the extrinsic coagulation pathway, which significantly increased likelihood of hemostatic disorders in early posttraumatic period.

Commentary on: Rivaroxaban for Venous Thromboembolism Prophylaxis in Abdominoplasty: A Multicenter Experience.

We appreciate the opportunity to review this article by Dr Hunstad and his colleagues.1 The authors report on observed rates of venous thromboembolism (VTE) and reoperative hematoma in a case series of 132 abdominoplasty patients who received chemoprophylaxis with rivaroxaban 10 mg daily beginning 12 hours after surgery and continuing for ≥7 days. The oral direct inhibitors of factor Xa (FXa) are the newest class of anticoagulant drugs and have ever-expanding indications. Factor X can be activated (to FXa) via either the intrinsic or extrinsic clotting pathways. FXa promotes conversion of prothrombin to thrombin, resulting in clot formation. Enoxaparin accelerates the activity of antithrombin, which accelerates the rate of inactivation of FXa. Inactivation of FXa subsequently decreases thrombin generation. Fondaparinux, the effect of which is largely mediated through FXa inhibition (with some inhibition of Factor IXa), is also an effective anticoagulant. Clinical utility of fondaparinux identified FXa as an appealing target for anticoagulants because it represents a unifying pathway of the extrinsic and intrinsic clotting pathways.2 Rivaroxaban is an oral direct inhibitor of FXa. Rivaroxaban is approved by the United States Food and Drug Administration for prevention of stroke and systemic embolism for patients with nonvalvular atrial fibrillation, treatment of acute VTE, long-term prevention of recurrent VTE after an initial 6 months of therapy, and prevention of VTE after total knee or hip arthroplasty. Approval was based on large phase III trials showing noninferior or superior efficacy and similar or reduced rates of major, intracranial, and fatal bleeding compared with conventional anticoagulants (ie, enoxaparin and/or warfarin).3-7 For patients undergoing total knee arthroplasty, rivaroxaban 10 mg daily reduced the primary outcome of VTE and death compared with enoxaparin 40 mg daily (9.6% vs 18.9%, P < .001) without increased bleeding.6 Similar findings were observed after …

Determining the effect of storage conditions on prothrombin time, activated partial thromboplastin time and fibrinogen concentration in rat plasma samples.

Coagulation parameters are usually included in clinical and preclinical safety studies to evaluate the effect of xenobiotics on the extrinsic or intrinsic pathways of coagulation. The analysis is generally performed at the time of terminal sacrifice where many activities are scheduled. Chances of delay in analysis are likely particularly when blood is collected for coagulation via the abdominal vena cava. This experiment was planned to assess the variations in coagulation parameters caused by delay in analysis as well as by storage conditions. Blood was collected from the posterior vena cava under isoflurane anesthesia, and the plasma was separated immediately. Coagulation parameters were evaluated at 0, 6, 24 and 48 h from the plasma stored at room temperature, as well as plasma stored under refrigerated and freezing conditions. Stability of the analytes in blood was also evaluated under refrigerated conditions for 6 h. All parameters were analyzed using a semi-automated coagulometer. Prothrombin time (PT) was stable under all three storage conditions for up to 6 h. Although statistically significant differences were observed for activated partial thromboplastin time (APTT) at room and refrigeration temperatures for up to 6 h, the difference was clinically non-relevant. Fibrinogen was found to be the most stable parameter that showed consistency in results even up to 48 h under all three storage conditions. Plasma for PT can be stored and analyzed without any significant changes for up to 6 h from the actual blood collection, while fibrinogen level testing can be extended for up to 48 h after collection under any storage condition. For reliable APTT results, plasma samples should be run immediately after collection.

Tissue factor and tissue factor pathway inhibitor in nasal mucosa and nasal secretions of chronic rhinosinusitis with nasal polyp.

Activation of the coagulation system with an increase in thrombin generation is involved in the pathogenesis of tissue remodeling in chronic rhinosinusitis (CRS). Tissue factor (TF) is an important protein for initiation of the extrinsic coagulation pathway, and TF pathway inhibitor (TFPI) is a regulator of TF-induced coagulation. This study was conducted to elucidate the roles of TF and TFPI in the pathogenesis of CRS. Tissue localization of TF, TFPI, and fibrin was determined by immunostaining of nasal polyps and inferior turbinates obtained during endonasal surgery in patients with CRS with nasal polyp (CRSwNP). Nasal secretions were collected from patients with CRSwNP, allergic rhinitis, and from control patients. The concentrations of TF and TFPI were measured in nasal secretions from each group. The concentrations of TF and TFPI released into culture medium by normal human nasal epithelial cells treated with thrombin, protease-activated receptor 1 agonist peptide, or tumor necrosis factor α were also measured. TF expression was localized in nasal epithelial cells and in infiltrating eosinophils of nasal mucosa. TFPI expression was localized in nasal epithelial cells, and fibrin deposition was observed in nasal secretions and the lamina propria of nasal polyps. Nasal secretions contained significant concentrations of TF and TFPI. The concentration of TFPI in nasal secretions correlated positively with thrombin activity and the concentration of thrombin-antithrombin III complex. Treatment with thrombin, protease-activated receptor 1 agonist peptide, or tumor necrosis factor α stimulated significant release of TF and TFPI from cultured nasal epithelial cells. By upregulating the coagulation system, TF and TFPI play an important role in the pathogenesis of CRSwNP.

Accelerated activation of the coagulation pathway during cardiopulmonary bypass in aortic replacement surgery: a prospective observational study.

BackgroundAny form of surgery or tissue damage causes release of tissue factor into the circulation. This may lead to the accelerated consumption of coagulation factors, resulting in severe consumptive coagulopathy. In this study, we compared the molecular markers involved in coagulation activation during cardiopulmonary bypass (CPB) between patients who underwent aortic replacement surgery and those who underwent valve surgery.MethodsThis prospective observational study was performed in each 14 patients who underwent aortic replacement surgery or valve surgery. We evaluated the differences in the levels of fibrinogen, activated factor VII (FVIIa), thrombin–antithrombin complex (TAT), and soluble fibrin monomer complex (SFMC) during surgery between these two groups.ResultsThe change in fibrinogen levels showed no difference between the groups. The magnitude of increase in TAT was much larger in patients who underwent aortic replacement surgery than in those who underwent valve surgery (173.6 vs. 49.4 ng/mL; p = 0.0001). More importantly, the elevation of FVIIa was significantly higher in patients who underwent aortic replacement (28.5 vs. 19.0 mU/mL; p = 0.0122). The magnitude of increase in SFMC was also larger in the aortic replacement surgery.ConclusionsThe activation of coagulation during CPB was dramatically higher in the aortic replacement surgery compared with the valve surgery, probably owing to the activation of the extrinsic coagulation pathway in the former. This could potentially exacerbate consumptive coagulopathy after CPB termination in patients who underwent aortic replacement, possibly resulting in massive hemorrhage due to impaired hemostasis.