Procoagulant Activity Of Phospholipids Research Articles

Coagulation in liver surgery: an observational haemostatic profile and thromboelastography study.

International normalized ratio (INR) is used as a marker of the haemostatic status following liver resection. However, the impact of liver resection on haemostasis is complex and beyond what can be measured by INR. This study aimed to prospectively assess haemostatic profile following liver resection and determine if INR measurement can safely guide post-operative thromboprophylaxis. In this prospective cohort study, patients undergoing liver resection had coagulation parameters (International normalised ratio (INR), prothrombin time (PT), activated partial thromboplastin time, fibrinogen, d-dimer, von Willebrand factor antigen, procoagulant activity of phospholipids and clotting factors II, VII, VIIIc, IX and X) and thromboelastogram parameters assessed perioperatively. Clinical follow-up assessed for thromboembolism and haemorrhage. In the 41 patients included, INR was significantly (P < 0.0001) elevated post-operatively, and INR >1.5 was observed in seven of 41 (17.1%) on post-operative day 1 and one of 41 (2.4%) patients on post-operative day 3, respectively. Factor VII levels showed transient reduction but other factors, especially factors II and X, remained within normal range following liver resection. Thromboelastogram parameters remained normal or supranormal for all patients at all time points. One incident of post-hepatectomy haemorrhage occurred, despite a normal coagulation profile. Two patients suffered late pulmonary embolic episodes. Post liver resection haemostasis is complex and poorly reflected by INR, which should not guide initiation of chemical thromboprophylaxis in the immediate post-operative period.

Treprostinil treatment decreases circulating platelet microvesicles and their procoagulant activity in pediatric pulmonary hypertension.

Pulmonary arterial hypertension (PAH) results from pulmonary vascular disease and may eventually lead to right heart failure and death. Vasodilator therapy has greatly improved PAH prognosis. Circulating microvesicles are considered as surrogate markers of endothelial and hematopoietic cell activation. Thus, our purpose was to determine if MVs are upregulated in pediatric PAH such as reported in adult patients, and to analyze the impact of vasodilator therapies on MV count and function. Population study consisted of 26 patients of median age 6.09 years, with Congenital Heart Disease (CHD) and elevated pulmonary vascular resistance (CHD-PAH) or idiopathic PAH (iPAH). Compared to healthy controls, all circulating MV subpopulations were found higher in untreated PAH patients. No significant differences of annexin-V+ total MV, endothelial, or leukocyte derived-MV counts were found between untreated patients and those receiving oral vasodilator therapies. Conversely, platelet MVs were significantly lower in the group treated with SC-treprostinil compared with both untreated PAH and oral therapy groups (P = 0.01), and exhibited a significant decrease of phospholipid procoagulant activity. Control samples treated in vitro with treprostinil at therapeutic concentrations showed as expected a significant decrease of platelet aggregation but also a reduced spontaneous MV generation. Our results suggest that treprostinil, besides vasodilation, might exert its beneficial effect through an inhibition of platelet activation, resulting in a decreased number and procoagulant activity of circulating MVs.

Increased risk of thrombosis in FcγRIIA 131RR patients with HIT due to defective control of platelet activation by plasma IgG2

AbstractThrombosis results in heparin-induced thrombocytopenia (HIT) from cellular activation involving Fc receptors. In this study, the FcγRIIA 131RR genotype was found to increase the risk of thrombosis in HIT patients (odds ratio: 5.9; 95% confidence interval: 1.7-20). When platelet aggregation tests (PATs) were performed with platelet-rich plasma (PRP), a shorter lag time was measured in 131RR donors compared to individuals with the HR and HH genotypes in response to HIT plasma or 5B9, a recently developed humanized monoclonal antibody to PF4/heparin. Importantly, this difference was no longer detectable when PATs were performed with washed platelets or immunoglobulin (Ig)G-depleted PRP. Moreover, polyclonal IgG or monoclonal IgG1 added to IgG-depleted PRP increased the lag time in response to 5B9. HH platelets were also sensitive to IgG2, which in contrast, failed to inhibit the response of 131RR platelets to 5B9. Finally, higher tissue factor messenger RNA levels were measured in the whole blood of 131RR donors after activation by HIT antibodies, with increased phospholipid procoagulant activity. These results demonstrate that HIT patients homozygous for the FcγRIIA 131R allele have a higher risk of thrombosis, probably due to increased cell activation by antibodies to PF4/heparin, with a lower inhibitory effect of endogenous IgG, especially from the IgG2 subclass.

Markers of Hypercoagulability in Breast Cancer: What Is Their Clinical Relevance?

AbstractAbstract 5133 IntroductionCancer is generally combined with an increased risk of venous thromboembolism. This risk is linked to a hypercoagulable state whose precise mechanism remains unclear. It depends on the histological type, the stage of cancer and the anti-neoplasic treatment. This study aims to identify a hypercoagulability in patients with breast cancer and to define the most relevant procoagulant markers. Materials and methodsA prospective study was carried out at the day hospital in the cancer department of the University Hospital H. Bourguiba in Sfax-Tunisia, from January to June 2012, including only patients with breast cancer. The thrombin generation was carried out on a venous citrated sampling (3. 2%) according to the technique of Calibrated Automated Thrombogram assay (CAT®, Diagnostica Stago, Asnières, France). The parameters of the thrombogram were analyzed: endogenous thrombin potential (ETP), peak of thrombin (peak) and mean rate index (MRI). The rates of platelet-derived microparticles expressing phosphatidyl-serine (MPP-PS+) were determined by flow cytometry using monoclonal antibodies anti-CD41 and anti-annexin V marked respectively by phycoerythrin (PE) and fluorescein isothiocyanate (FITC). D-dimers were measured by the STA-Liatest D-DI (Diagnostica-Stago) technique. The procoagulant activity of phospholipids (PPL) was measured by STA®-Procoag-PPL (Diagnostica-Stago). The plasma levels of tissue factor (TFa) were measured in a one-stage kinetic chromogenic method. This home-assay measures the ability of TF-FVIIa to activate factor X. ResultsSixty one patients were included. Their mean age was 51. 8 ± 10. 9 years old. The study of the thrombogram parameters showed a significant increase of the peak of thrombin (343. 8±79. 2 nM) and of the velocity or MRI (153±56 nM/min) in patients compared to control subjects (288±48 nM, p=0. 001 and 109±33 nM/min, p<0. 001 respectively). Only 36% of patients had a significant increase of thrombin generation. D-dimers levels reached in average 1230±1760 ng/ml and 61% of patients presented relevant high values (>500 ng/ml). MPP-PS+ in cancer patients were significantly higher (9684±7865/μl) than in controls (695±361/μl, p<0. 001) but nearly 94% of patients present particularly high levels of this parameter (≥1614/μl). PPL levels were significantly higher in patients with a shorter time compared to controls (43. 4±10. 4sec versus 72 sec ± 5. 6 sec) with 97% of cancer patients below the inferior limit (60. 8sec). Besides, TFa levels were significantly increased in patients (1. 6±1. 2 pM) compared to controls (0. 22pM ± 0. 12) with 87% of cancer patients presenting particularly high values (≥0. 46pM). ConclusionBreast cancer, considered more like a tumor with a low vascular risk, is combined with a state of cell activation and hypercoagulation, almost constant, reflected by an increase of procoagulant microparticles, TF and PPL levels. Besides, thrombin generation showed a less pronounced increase in this clinical context and could contribute to discriminate patients with high or low high risk of thrombosis in breast cancer patients. This has to be confirmed by prospective studies with a clinical follow-up of cancer patients. Disclosures:No relevant conflicts of interest to declare.

The anticoagulant action of phospholipase A from Eresus niger spider venom

P. B. Usmanov and F. A. Nuritova. The anticoagulant action of phospholipase A from Eresus niger spider venom. Toxicon 32, 625–628, 1994.—Phospholipase A, named component EnPA, was isolated from Eresus niger spider venom. It was determined to be a single peptide chain with mol. wt of 13,000. Component EnPA showed high anticoagulant activity when the APTT was measured in spite of its low enzymatic activity (30 ± 6 μmol/min/mg). It was concluded that anticoagulant action of compound EnPA is due to inactivation of the procoagulant activity of phospholipids because of its high binding with them.

Purification and characterization of the anticoagulant principle of Trimeresurus mucrosqualatus venom

By means of CM-Sephadex column chromatography, Trimeresurus mucrosquamatus venom was separated into 20 fractions. Fraction XX had the marked anticoagulant action. This fraction was refractionated three times on Sephadex G-75, and a single peak was obtained. The patterns of microzone and disc electrophoresis also showed a single band. A single, symmetrical boundary with a value of 1.61 S was obtained by ultracentrifugation. It was a single peptide chain with a molecular weight of 11 700. The isoelectric point was higher than pH 10. The anticoagulant principle possesses phospholipase A activity and was calcium ion dependent. It did not possess proteolytic, tosyl- L-arginine methyl ester esterase, phosphodiesterase and alkaline phosphomonoesterase activities of the crude venom. The phospholipase A activity was heat-labile at pH 7.4, but was heat-stable at pH 5.6. The anticoagulant activity was more resistant to heat treatment as compared with phospholipase A activity. The anticoagulant action of the purified principle was competitively inhibited by platelet phospholipid, tissue thromboplastin and cephalin, and was neutralized by antiserum. The anticoaugulant principle inhibited platelet aggregation induced by ADP. It did not destroy fibrinogen, Factor X, prothrombin and thrombin; nor did it induce fibrinolysis nor interfere with the interaction between thrombin and fibrinogen. It is concluded that the anticoagulant action of this phospholipase A was due to the inhibition of the activations of Factors X and II through the activation of the procoagulant activity of phospholipids mediated partly by phospholipid-binding activity of this venom enzyme and partly by its enzymatic hydrolysis of phospholipids.

Assessment of procoagulant activity of phospholipids with a venom specific inhibitor : M. C. Boffa, Laboratoire d'Hemostase, Centre National de Transfusion Sanguine, Paris, France

Assessment of procoagulant activity of phospholipids with a venom specific inhibitor : M. C. Boffa, Laboratoire d'Hemostase, Centre National de Transfusion Sanguine, Paris, France