Investigation of an anti-activated factor X (anti-Xa) assay for the quantification of enoxaparin in human plasma

2014 ◽  
Vol 67 (2) ◽  
pp. 209-214 ◽  
Author(s):  
Hesham S. Al-Sallami ◽  
Natalie J. Medlicott
Keyword(s):  
Human Plasma ◽  
Factor X

A Chromogenic Factor X Assay With New Standardized Reagents

1979 ◽  
Author(s):  
P Friberger ◽  
C Lenne
Keyword(s):  
Human Plasma ◽  
Suitable Method ◽  
Chromogenic Substrate ◽  
Factor X ◽  
Normal Human Plasma ◽  
Normal Plasma ◽  
Normal Human

A recently published method for Factor X (FX) assay (1) utilizing Russel's Viper Venom (RVV) and a chromogenic substrate has been further investigated by testing a large number of parameters. This method has been considered as a suitable method for monitoring coumarol treatment (Bergström et al).The conditions for the activation of FX by purified preparations of the RVV have been studied as well as the conditions for FXa determination with a new chromogenic substrate Bz-Ile-Glu(γ-piperidyl)-Gly-Arg-pNA (S-2337). Both purified factors and normal plasma have been used. The effect of plasma inhibitors as well as the selectivity of the method has been studied.The reproducibility and stability of the different reagents and standards have been studied and found to be good.The amount of FXa activity obtained from normal human plasma has been titrated with FXa inhibitors of known purity.1) Aurell L. et al, Thromb. Res., 11, 595 (1977)2) Bergström et al, Thromb. Res., 12, 531 (1978)

A Hitherto Undescribed Naturally Occurring Plasma Antagonist of Activated Factor X Inhibitor (Antithrombin III)

1979 ◽  
Author(s):  
E. T. Yin ◽  
W. J. Salsgiver ◽  
O. Tangen
Keyword(s):  
Equilibrium State ◽  
Human Plasma ◽  
Antithrombin Iii ◽  
Circumstantial Evidence ◽  
Incubation Mixture ◽  
Factor X ◽  
Normal Human Plasma ◽  
Plasma Component ◽  
Naturally Occurring ◽  
Normal Human

Circumstantial evidence suggested that normal human plasma contained a substance regulating the neutralization of F.Xa by F.Xa inhibitor(XaI), (Yin et.al.,Adv.Exper. Med. & Biol., 52 : 239, 1975, Plenum Press, N.Y.).This plasma component has now been isolated and partially purified in our laboratory, and tentatively designated as “Anti-XaI”.In experiments employing purified components, when Anti-XaI was incubated at 37°C with F.Xa, Xal and heparin for two minutes at pH7.5, the amount of F.Xa inhibited was inversely proportional to the Anti-XaI concentration. But, when the F.Xa was replaced by thrombin in the incubation mixture, the neutralization of thrombin clotting activity was undisturbed.Anti-XaI was found to be neither PF3 nor PF4.These and other data strongly suggest that the “Antithrombin III pathway” is more complex than currently believed to be. In circulating blood an equilibrium state must exist between Anti-XaI and XaI.Under certain conditions when the Anti-XaI activity is predominant the rate of F.Xa neutralization bv XaI then becomes slower than the activation of prothrombin to thrombin by F.Xa.

scholarly journals A Genus-Wide Bioactivity Analysis of Daboia (Viperinae: Viperidae) Viper Venoms Reveals Widespread Variation in Haemotoxic Properties

2021 ◽  
Vol 22 (24) ◽  
pp. 13486
Author(s):  
Bianca op den Brouw ◽  
Francisco C. P. Coimbra ◽  
Nicholas R. Casewell ◽  
Syed Abid Ali ◽  
Freek J. Vonk ◽  
...  
Keyword(s):  
Sri Lanka ◽  
Human Plasma ◽  
Dose Response ◽  
Factor X ◽  
African Species ◽  
Human Fibrinogen ◽  
Fibrinogenolytic Activity ◽  
The Many ◽  
Viper Venoms ◽  
Multiple Variants

The snake genus Daboia (Viperidae: Viperinae; Oppel, 1811) contains five species: D. deserti, D. mauritanica, and D. palaestinae, found in Afro-Arabia, and the Russell’s vipers D. russelii and D. siamensis, found in Asia. Russell’s vipers are responsible for a major proportion of the medically important snakebites that occur in the regions they inhabit, and their venoms are notorious for their coagulopathic effects. While widely documented, the extent of venom variation within the Russell’s vipers is poorly characterised, as is the venom activity of other species within the genus. In this study we investigated variation in the haemotoxic activity of Daboia using twelve venoms from all five species, including multiple variants of D. russelii, D. siamensis, and D. palaestinae. We tested the venoms on human plasma using thromboelastography, dose-response coagulometry analyses, and calibrated automated thrombography, and on human fibrinogen by thromboelastography and fibrinogen gels. We assessed activation of blood factors X and prothrombin by the venoms using fluorometry. Variation in venom activity was evident in all experiments. The Asian species D. russelii and D. siamensis and the African species D. mauritanica possessed procoagulant venom, while D. deserti and D. palaestinae were net-anticoagulant. Of the Russell’s vipers, the venom of D. siamensis from Myanmar was most toxic and D. russelli of Sri Lanka the least. Activation of both factor X and prothrombin was evident by all venoms, though at differential levels. Fibrinogenolytic activity varied extensively throughout the genus and followed no phylogenetic trends. This venom variability underpins one of the many challenges facing treatment of Daboia snakebite envenoming. Comprehensive analyses of available antivenoms in neutralising these variable venom activities are therefore of utmost importance.

The Clotting of a Snake (Crotalus Viridis Helleri) Plasma and its Interaction with Various Snake Venoms

1976 ◽  
Vol 35 (02) ◽  
pp. 314-323 ◽  
Author(s):  
K.W.E Denson
Keyword(s):  
Human Plasma ◽  
Factor Xa ◽  
Factor X ◽  
Snake Venoms ◽  
Crotalus Viridis ◽  
Fibrin Monomer ◽  
Russell’S Viper ◽  
Marked Specificity ◽  
Bovine Factor

SummaryThe clotting of C. V. Helleri plasma is not accelerated by the factor X activator or throm-bin-like enzymes from its own venom. Clotting of the plasma is accelerated by the factor X activator from Russell’s viper venom, but not by the thrombin-like enzyme from Agkistrodon Rhodostoma venom (“Arvin”).The prothrombin activator from the Taipan venom clots C. V. Helleri plasma equally well as human plasma, but the thrombin which is produced has a marked specificity for its own fibrinogen, and clots bovine fibrinogen more slowly.C. V. Helleri plasma contains an inhibitor which progressively inactivates bovine factor Xa and thrombin, but the inhibitor is not potentiated by heparin. The slow, protracted clotting of the snake plasma either alone or when mixed with human plasma or bovine fibrinogen suggests that this inhibitor may interfere with the polymerisation of fibrin monomer.

A Comparison of Plasma and Serum Factor VII Activity and the Formation of Tissue Thromboplastin

1962 ◽  
Vol 08 (02) ◽  
pp. 286-296
Author(s):  
P Fantl ◽  
E. C Osborn
Keyword(s):  
Human Brain ◽  
Human Plasma ◽  
Factor Vii ◽  
Brain Extract ◽  
Factor X ◽  
Similar Activity ◽  
Bovine Plasma ◽  
Tissue Thromboplastin ◽  
Species Specific ◽  
Glass Surfaces

Summary1. A mixture of human serum or plasma and bovine plasma free of factors VII and X gave, with human brain extract, identical clotting times.2. An assay of factor VII in materials low in prothrombin using human plasma euglobulin was devised.3. Factor VII isolated from human plasma or serum gave similar activity with human brain extract.4. From a preparation containing factors VII and X which was added to human brain extract in the average 31% factor VII and 25% factor X was recovered. This was not dependent on the activity of factors VII and X in the original preparation. This indicates that factors VII and X are in equilibrium with tissue thromboplastin.5. Factors VII and X are not species specific but a higher concentration of these factors is required for prothrombin conversion in a heterologous reaction mixture.6. Factor VII activity is identical in silicone-coated or uncoated glass surfaces.

Thromboplastic Effects ot Human Plasma Lipoproteins

1975 ◽  
Author(s):  
L.-O. Andersson ◽  
H. Sandberg
Keyword(s):  
Human Plasma ◽  
Platelet Rich Plasma ◽  
Density Lipoprotein ◽  
High Density ◽  
Plasma Lipoproteins ◽  
High Density Lipoproteins ◽  
Phospholipid Content ◽  
Factor X ◽  
Promoting Effect ◽  
Free Plasma

Lipoprotein fractions from human plasma was prepared by ultracentrifugal flotation. Additions of those fractions to plasma containing various amounts of platelets showed that in platelet-poor and platelet-free plasma there was a clear clot-promoting effect of the additions. In platelet-rich plasma, this effect was negligible. Measurements on the thrombo-plastine and Stypven clotting times showed that the high density lipoprotein fraction affected both the prothrombin and the Factor X activation steps whereas the low density lipoproteins only influenced the prothrombin activation step. Addition of antibodies against high density lipoproteins to platelet-free plasma caused a prolongation of the thromboplastin time.The relation between lipoprotein structure, phospholipid content and thromboplastic effects is dicussed.

scholarly journals Mass spectrometry based analysis of human plasma-derived factor X revealed novel post-translational modifications

2015 ◽  
Vol 24 (10) ◽  
pp. 1640-1648 ◽  
Author(s):  
Guillaume Chevreux ◽  
Nolwenn Tilly ◽  
Valegh Faid ◽  
Nicolas Bihoreau
Keyword(s):  
Mass Spectrometry ◽  
Human Plasma ◽  
Factor X ◽  
Post Translational Modifications

scholarly journals Tissue factor-dependent activation of tritium-labeled factor IX and factor X in human plasma

Blood ◽  
1984 ◽  
Vol 63 (6) ◽  
pp. 1338-1347 ◽  
Author(s):  
SA Morrison ◽  
J Jesty
Keyword(s):  
Human Plasma ◽  
Tissue Factor ◽  
Factor Viia ◽  
Stimulate Factor ◽  
Specific Inhibitor ◽  
Factor Xa ◽  
Factor Ix ◽  
Factor Vii ◽  
Factor X ◽  
Bovine Plasma

Recent investigations have suggested that the activation of factor IX by factor VII/tissue factor may be an important alternative route to the generation of factor Xa. Accordingly, we have compared the tissue factor-dependent activation of tritium-labeled factor IX and factor X in a human plasma system and have studied the role of proteases known to stimulate factor VII activity. Plasma was defibrinated by heating and depleted of its factors IX and X by passing it through antibody columns. Addition of human brain thromboplastin, Ca2+, and purified 3H- labeled factor X to the plasma resulted, after a short lag, in burst- like activation of the factor X, measured as the release of radiolabeled activation peptide. The progress of activation was slowed by both heparin and a specific inhibitor of factor Xa, suggesting a feedback role for this enzyme, but factor X activation could not be completely abolished by such inhibitors. In the case of 3H-factor IX activation, the rate also increased for approximately 3 min after addition of thromboplastin, but was not subsequently curtailed. A survey of proteases implicated as activators of factor VII in other settings showed that both factor Xa and (to a much smaller extent) factor IXa could accelerate the activation of factor IX. However, factor Xa was unique in obliterating activation when present at concentrations greater than approximately 1 nM. Heparin inhibited the tissue factor-dependent activation of factor IX almost completely, apparently through the effect of antithrombin on the feedback reactions of factors Xa and IXa on factor VII. These results suggest that a very tight, biphasic control of factor VII activity exists in human plasma, which is modulated mainly by factor Xa. Variation of the factor IX or factor X concentrations permitted kinetic parameters for each activation to be derived. At saturation of factor VIIa/tissue factor, factor IX activation was significantly more rapid than was previously found in bovine plasma under similar conditions. The activation of factor X at saturation was slightly more rapid than in bovine plasma, despite the presence of heparin.

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