scholarly journals In vivo studies of the role of factor VII in hemostasis

Blood ◽  
1985 ◽  
Vol 65 (5) ◽  
pp. 1197-1200 ◽  
Author(s):  
AR Giles ◽  
S Tinlin ◽  
L Brosseau ◽  
H Hoogendoorn
Keyword(s):  
Alternative Pathway ◽  
Factor Xa ◽  
In Vivo Studies ◽  
Factor Vii ◽  
High Dose ◽  
Factor X ◽  
Clotting Factors ◽  
Dose Warfarin ◽  
Factor X Activation

Abstract The effect of both congenital and acquired factor VII deficiency on the cuticle bleeding time (CBT) was evaluated in dogs. The CBT has been previously documented to be a sensitive indicator of factor VIII:C deficiency in hemophilic dogs. Serial CBT determinations were made on normal dogs treated with high-dose warfarin. At 48 hours post- treatment, the CBT was normal, although the factor VII level was less than 1%, whereas the levels of factors II, IX, and X were 44%, 25%, and 17%, respectively. At 120 hours the CBT became abnormal when all vitamin K-dependent clotting factors had dropped to less than 18%. Administration of a plasma concentrate of factors II, IX, and X corrected the CBT, despite the factor VII level remaining at less than 1%. Similar studies in a congenitally factor VII-deficient dog (factor VII less than 2%) confirmed that this deficiency state was not associated with an abnormality of the CBT. Administration of heparin to both normal and factor VII-deficient animals was associated with prolongation of the CBT, but the heparin dose required in the normal animals was substantially higher than in the factor VII-deficient animals. These data do not suggest that factor VII/VIIa has an exclusive role in generating factor Xa, either directly or indirectly, by way of factor IXa generation, in vivo. However, the increase in heparin sensitivity of the factor VII-deficient animals does suggest that factor VII/VIIa may, in some circumstances, present a significant alternative pathway of factor X activation, although the activation pathway involved cannot be determined from the studies performed.

scholarly journals In vivo studies of the role of factor VII in hemostasis

Blood ◽  
1985 ◽  
Vol 65 (5) ◽  
pp. 1197-1200
Author(s):  
AR Giles ◽  
S Tinlin ◽  
L Brosseau ◽  
H Hoogendoorn
Keyword(s):  
Alternative Pathway ◽  
Factor Xa ◽  
In Vivo Studies ◽  
Factor Vii ◽  
High Dose ◽  
Factor X ◽  
Clotting Factors ◽  
Dose Warfarin ◽  
Factor X Activation

The effect of both congenital and acquired factor VII deficiency on the cuticle bleeding time (CBT) was evaluated in dogs. The CBT has been previously documented to be a sensitive indicator of factor VIII:C deficiency in hemophilic dogs. Serial CBT determinations were made on normal dogs treated with high-dose warfarin. At 48 hours post- treatment, the CBT was normal, although the factor VII level was less than 1%, whereas the levels of factors II, IX, and X were 44%, 25%, and 17%, respectively. At 120 hours the CBT became abnormal when all vitamin K-dependent clotting factors had dropped to less than 18%. Administration of a plasma concentrate of factors II, IX, and X corrected the CBT, despite the factor VII level remaining at less than 1%. Similar studies in a congenitally factor VII-deficient dog (factor VII less than 2%) confirmed that this deficiency state was not associated with an abnormality of the CBT. Administration of heparin to both normal and factor VII-deficient animals was associated with prolongation of the CBT, but the heparin dose required in the normal animals was substantially higher than in the factor VII-deficient animals. These data do not suggest that factor VII/VIIa has an exclusive role in generating factor Xa, either directly or indirectly, by way of factor IXa generation, in vivo. However, the increase in heparin sensitivity of the factor VII-deficient animals does suggest that factor VII/VIIa may, in some circumstances, present a significant alternative pathway of factor X activation, although the activation pathway involved cannot be determined from the studies performed.

scholarly journals Initiation of the extrinsic pathway of coagulation by human and rabbit alveolar macrophages: a kinetic study

Blood ◽  
1989 ◽  
Vol 74 (5) ◽  
pp. 1583-1590 ◽  
Author(s):  
MP McGee ◽  
R Wallin ◽  
FB Wheeler ◽  
H Rothberger
Keyword(s):  
Alveolar Macrophage ◽  
Alveolar Macrophages ◽  
Plasma Concentrations ◽  
Factor Xa ◽  
Factor Vii ◽  
Factor X ◽  
Extrinsic Pathway ◽  
Activation Rate ◽  
Factor X Activation

We examined assembly and expression of the factor X activating complex on human and rabbit alveolar macrophages. Kinetic parameters of the factor X activating reaction were determined by functional titrations of factors VII and X with macrophage tissue factor (TF) added. We found rapid activation of factor X to Xa on alveolar macrophage surfaces. Detection of rapid factor Xa formation on macrophages required addition of exogenous factors VII and X. At plasma concentrations of the purified factors, factor Xa was formed on freshly isolated macrophages at approximately 5.4 pmol/min/10(6) cells. After macrophage maturation in culture for 20 hours with LPS (endotoxin) added, the factor X activation rate was increased two- to sixfold. The km' (apparent km) of TF-factor VII enzymatic complexes assembled on alveolar macrophages for factor X were (258 +/- 55 and 475 +/- 264 nmol/L for human and rabbit cells, respectively). The km' did not change during macrophage maturation in culture, but V'max (apparent Vmax) was consistently increased. The K1/2 of human factor VII (concentrations giving half maximal rates of factor X activation) for the interaction with human and rabbit alveolar macrophage TF were 0.191 +/- 0.096 and 1.7 +/- 0.7 etamol/L, respectively. The K1/2 were not significantly changed after maturation, whereas rates of Xa formation at saturation with factor VII were increased. The fast rates of factor X activation observed at physiologic concentrations of plasma-derived factors VII and X indicate that TF on alveolar macrophages is likely to provide sites for binding of factor VII and activation of factor X in vivo during clotting reactions associated with alveolar edema and inflammation.

scholarly journals Initiation of the extrinsic pathway of coagulation by human and rabbit alveolar macrophages: a kinetic study

Blood ◽  
1989 ◽  
Vol 74 (5) ◽  
pp. 1583-1590 ◽  
Author(s):  
MP McGee ◽  
R Wallin ◽  
FB Wheeler ◽  
H Rothberger
Keyword(s):  
Alveolar Macrophage ◽  
Alveolar Macrophages ◽  
Plasma Concentrations ◽  
Factor Xa ◽  
Factor Vii ◽  
Factor X ◽  
Extrinsic Pathway ◽  
Activation Rate ◽  
Factor X Activation

Abstract We examined assembly and expression of the factor X activating complex on human and rabbit alveolar macrophages. Kinetic parameters of the factor X activating reaction were determined by functional titrations of factors VII and X with macrophage tissue factor (TF) added. We found rapid activation of factor X to Xa on alveolar macrophage surfaces. Detection of rapid factor Xa formation on macrophages required addition of exogenous factors VII and X. At plasma concentrations of the purified factors, factor Xa was formed on freshly isolated macrophages at approximately 5.4 pmol/min/10(6) cells. After macrophage maturation in culture for 20 hours with LPS (endotoxin) added, the factor X activation rate was increased two- to sixfold. The km' (apparent km) of TF-factor VII enzymatic complexes assembled on alveolar macrophages for factor X were (258 +/- 55 and 475 +/- 264 nmol/L for human and rabbit cells, respectively). The km' did not change during macrophage maturation in culture, but V'max (apparent Vmax) was consistently increased. The K1/2 of human factor VII (concentrations giving half maximal rates of factor X activation) for the interaction with human and rabbit alveolar macrophage TF were 0.191 +/- 0.096 and 1.7 +/- 0.7 etamol/L, respectively. The K1/2 were not significantly changed after maturation, whereas rates of Xa formation at saturation with factor VII were increased. The fast rates of factor X activation observed at physiologic concentrations of plasma-derived factors VII and X indicate that TF on alveolar macrophages is likely to provide sites for binding of factor VII and activation of factor X in vivo during clotting reactions associated with alveolar edema and inflammation.

A Distinction between the Role of Precursor and Activated Forms of Clotting Factors in the Genesis of Stasis Thrombi

1967 ◽  
Vol 18 (01/02) ◽  
pp. 012-023 ◽  
Author(s):  
S Wessler ◽  
E. T Yin ◽  
L. W Gaston ◽  
Iona Nicol
Keyword(s):  
Human Serum ◽  
Factor Ix ◽  
In Vivo Studies ◽  
Factor Vii ◽  
Factor X ◽  
Clotting Factors ◽  
Insight Into

Summary1. In vivo studies in rabbits have shown that the liver diminishes the thrombo-genicity of infused human serum.2. In vitro rabbit liver perfusions with human serum have demonstrated the loss of serum thrombogenicity within 5 min after the onset of the perfusion. Associated with this loss of thrombotic capacity is a marked decrease in the activation product (AP) and labile factor IX (PPA) activity in the infused serum.3. The liver appears to have the capacity to discriminate between circulating activated clotting activities such as AP and PPA and inactive procoagulants such as stable or genuine factor IX, factor VII and factor X. The latter are not cleared from the circulation by the liver.4. These studies provide some insight into the mechanism whereby circulating activated clotting activities and retarded blood flow predispose to thrombosis.

scholarly journals Pan-American Lancehead Pit-Vipers: Coagulotoxic Venom Effects and Antivenom Neutralisation of Bothrops asper and B. atrox Geographical Variants

Toxins ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 78
Author(s):  
Lachlan A. Bourke ◽  
Christina N. Zdenek ◽  
Edgar Neri-Castro ◽  
Melisa Bénard-Valle ◽  
Alejandro Alagón ◽  
...  
Keyword(s):  
Evolutionary Biology ◽  
Current Knowledge ◽  
Clinical Manifestations ◽  
In Vivo Studies ◽  
Factor X ◽  
Clotting Factors ◽  
Bothrops Asper ◽  
Species Specific

The toxin composition of snake venoms and, thus, their functional activity, can vary between and within species. Intraspecific venom variation across a species’ geographic range is a major concern for antivenom treatment of envenomations, particularly for countries like French Guiana that lack a locally produced antivenom. Bothrops asper and Bothrops atrox are the most medically significant species of snakes in Latin America, both producing a variety of clinical manifestations, including systemic bleeding. These pathophysiological actions are due to the activation by the venom of the blood clotting factors Factor X and prothrombin, thereby causing severe consumptive coagulopathy. Both species are extremely wide-ranging, and previous studies have shown their venoms to exhibit regional venom variation. In this study, we investigate the differential coagulotoxic effects on human plasma of six venoms (four B. asper and two B. atrox samples) from different geographic locations, spanning from Mexico to Peru. We assessed how the venom variation of these venom samples affects neutralisation by five regionally available antivenoms: Antivipmyn, Antivipmyn-Tri, PoliVal-ICP, Bothrofav, and Soro Antibotrópico (SAB). The results revealed both inter- and intraspecific variations in the clotting activity of the venoms. These variations in turn resulted in significant variation in antivenom efficacy against the coagulotoxic effects of these venoms. Due to variations in the venoms used in the antivenom production process, antivenoms differed in their species-specific or geographical neutralisation capacity. Some antivenoms (PoliVal-ICP, Bothrofav, and SAB) showed species-specific patterns of neutralisation, while another antivenom (Antivipmyn) showed geographic-specific patterns of neutralisation. This study adds to current knowledge of Bothrops venoms and also illustrates the importance of considering evolutionary biology when developing antivenoms. Therefore, these results have tangible, real-world implications by aiding evidence-based design of antivenoms for treatment of the envenomed patient. We stress that these in vitro studies must be backed by future in vivo studies and clinical trials before therapeutic guidelines are issued regarding specific antivenom use in a clinical setting.

scholarly journals Activated clotting factors in factor IX concentrates

Blood ◽  
1979 ◽  
Vol 54 (5) ◽  
pp. 1028-1038 ◽  
Author(s):  
MB Hultin
Keyword(s):  
Antithrombin Iii ◽  
Initial Rate ◽  
Factor Xa ◽  
Factor Ix ◽  
Clinical Settings ◽  
Factor X ◽  
Clotting Factors ◽  
Factor Ixa ◽  
Human Factor Ix ◽  
Factor X Activation

Abstract The precise quantitation of activated factors in human factor IX concentrates has been accomplished with the use of recently developed, specific assays for factors IXa, Xa, and thrombin. The assay for factor IXa, which measures the initial rate of 3H-factor-X activation, was shown to be specific for factor IXa in the concentrates. Activated factor IX concentrates contained 1.0–2.3 microgram/ml of factor IXa; whereas the assays of unactivated concentrates were negative (less than 0.2 microgram/ml). The assays of factor Xa and thrombin, which measure the initial rate of p-nitroaniline release from S-2222 and S-2238, respectively, showed similar small amounts of factor Xa (4–34 ng/ml) and thrombin (12–76 ng/ml) in the activated and unactivated concentrates. The nonactivated partial thromboplastin time of the concentrates correlated significantly with the factor IXa content, but not with factor Xa or thrombin. Antithrombin III antigen in 3 of 4 concentrates was several-fold higher than antithrombin III activity, suggesting the presence of antithrombin III complexed with activated factors. These results support the hypothesis that the degree of activation of factor IX concentrates is related primarily to the concentration of factor IXa, which may be responsible for the thrombogenicity of these concentrates in some clinical settings.

scholarly journals Activation of Mac-1 (CD11b/CD18)-bound factor X by released cathepsin G defines an alternative pathway of leucocyte initiation of coagulation

1996 ◽  
Vol 319 (3) ◽  
pp. 873-879 ◽  
Author(s):  
Janet PLESCIA ◽  
Dario C ALTIERI
Keyword(s):  
Factor Viia ◽  
Alternative Pathway ◽  
Limited Proteolysis ◽  
Factor Xa ◽  
Peptide Bond ◽  
Cathepsin G ◽  
Activate Factor ◽  
Factor X ◽  
Proteolytic Activation

Leucocyte initiation of coagulation preserves the haemostatic balance and may aberrantly contribute to vascular injury. In addition to the extrinsic activation mediated by tissue factor: factor VIIa, monocytes express an alternative procoagulant response after binding of the zymogen factor X to the integrin Mac-1 (CD11b/CD18). Here, factor X-activating activity was found in purified monocyte granules, and coincided with size-chromatographed fractions containing cathepsin G. In contrast, elastase-containing granule fractions did not activate factor X. In the presence of Ca2+ ions, purified cathepsin G, but not elastase, cleaved factor X to a ∼ 54 kDa catalytically active derivative, structurally indistinguishable from the procoagulant product generated on monocytes after binding to Mac-1. Factor X activation by purified cathepsin G involved limited proteolysis of a novel Leu177-Leu178 peptide bond in the zymogen's activation peptide. Cathepsin G activation of factor X was completely inhibited by α1 antitrypsin, α1 antichymotrypsin, or soybean trypsin inhibitor, or by a neutralizing antiserum to cathepsin G, while eglin, or an anti-elastase antibody, were ineffective. Affinity chromatography on active-site-dependent inhibitors Glu-Gly-Arg-chloromethyl ketone or benzamidine completely abolished factor Xa activity generated by cathepsin G. Cathepsin G was not constitutively detected on the monocyte surface by flow cytometry. However, inflammatory stimuli, including formyl peptide or phorbol ester, or Mac-1 engagement with its ligands fibrinogen, factor X or serum-opsonized zymosan, triggered monocyte degranulation and cathepsin G activation of factor X. These findings demonstrate that monocytes can alternatively initiate coagulation in a sequential three-step cascade, including (i) binding of factor X to Mac-1, (ii) discharge of azurophil granules, and (iii) limited proteolytic activation of membrane-bound factor X by cathepsin G. By rapidly forming thrombin and factor Xa in a protected membrane microenvironment, this pathway may contribute a ‘priming’ signal for clotting, anticoagulation and vascular cell signal transduction, in vivo.

scholarly journals Coagulation Factor IX concentrate: method of preparation and assessment of potential in vivo thrombogenicity in animal models

Blood ◽  
1984 ◽  
Vol 64 (6) ◽  
pp. 1220-1227
Author(s):  
D Menache ◽  
HE Behre ◽  
CL Orthner ◽  
H Nunez ◽  
HD Anderson ◽  
...  
Keyword(s):  
Animal Models ◽  
Specific Activity ◽  
Rabbit Model ◽  
Coagulation Factor ◽  
Factor Ix ◽  
Factor Vii ◽  
Factor X ◽  
Clotting Factors ◽  
Coagulation Factor Ix

Thrombosis and/or disseminated intravascular coagulation (DIC) are complications specifically associated with the use of factor IX complex in some patients. Assuming that these complications might result from zymogen overload, we have produced, using diethylaminoethyl (DEAE)- Sephadex (Pharmacia, Piscataway, NJ) and sulfated dextran chromatography, a factor IX concentrate (coagulation factor IX) that is essentially free of prothrombin, factor VII, and factor X. Factor IX specific activity is at least 5 U/mg protein, a 250-fold purification compared to plasma. Amounts of factors II, VII, and X are less than 5 units each per 100 units of factor IX. The concentrate is essentially free of activated clotting factors and contains no added heparin. In the rabbit stasis model, a dose of 200 factor IX U/kg was less thrombogenic than 100 factor IX U/kg of the DEAE-Sephadex eluate from which the concentrate was derived. Infusion of 200 factor IX U/kg did not induce DIC in the nonstasis rabbit model, whereas 100 factor IX U/kg of the DEAE-Sephadex eluate resulted in DIC in this model. Several factor IX lots were found to have shortened nonactivated partial thromboplastin times (PTTs), but were nonthrombogenic in both animal models. These data indicate that coagulation factor IX concentrate is less thrombogenic than factor IX complex.

MECHANISMS OF PROCOAGULANT GENERATION BY ALVEOLAR MACROPHAGES DURING MATURATION

1987 ◽  
Author(s):  
Maria McGee ◽  
Henry Rothberger
Keyword(s):  
Alveolar Macrophages ◽  
Cultured Cells ◽  
Factor Xa ◽  
Procoagulant Activity ◽  
Factor Vii ◽  
Factor X ◽  
Extrinsic Pathway ◽  
Complex Assembly

During maturation in vivo and in vitro alveolar macrophages generate procoagulant(s) capable of activating the extrinsic pathway. It is generally agreed that at least part of the activity is due to TF (tissue factor). However, whether or not macrophages also generate functional factor VII or X is controversial. To characterize procoagulant activity increases, we measured kinetic parameters defining interactions between components of the TF-VII complex on membranes of alveolar macrophages either freshly isolated or cultured in serum free medium. In incubation mixtures with fixed concentrations of macrophages and added factor VII, the rate of factor Xa formation (measured by S-2222 hydrolysis) approached a maximum as factor X concentration was increased. Estimated concentrations of factor X yielding 1/2 maximal activation rates, (apparent Km) were 127.1±26 nM and 99.7±34 nM for fresh and cultured cells, respectively. Vmax (maximal velocities) were 1.21±0.24 and 8.9±5 nM Xa/min/106 cells. When concentrations of added factor X were kept constant, the rate of factor X activation increased as the added factor VII concentration was increased. For fresh and cultured cells, the respective apparent Kd were 1.810.7 and 1.410.25 nM. Maximal rates observed with X concentration fixed at 108 nM were 0.46±10.06 and 5.7±1.6 nM Xa/min/106 cells. In the absence of either added factor X or added factor VII, no factor Xa generation was detected in fresh or cultured cells, during 10-20 min incubation periods used for kinetic studies. The observed increase in Vmax without changes in apparent Km and Kd indicate that gains in procoagulant activity during macrophage maturation are due to increases in the number of functional binding sites for factor VII, without significant generation of functional vitamin K dependent factors (VII and X) by the cells. The data also indicate that maturation does not alter the rate behaviour of the TF-VII enzymatic complex on macrophage membranes. Mechanisms of complex assembly that we observed on macrophage membranes are similar to those described for the TF-VII complex assembly on purified systems.

scholarly journals Characterization of the inhibition of tissue factor in serum

Blood ◽  
1987 ◽  
Vol 69 (1) ◽  
pp. 150-155 ◽  
Author(s):  
GJ Jr Broze ◽  
JP Miletich
Keyword(s):  
Tissue Factor ◽  
Factor Viia ◽  
Factor Xa ◽  
Inhibitory Effect ◽  
Factor Vii ◽  
Factor X ◽  
Human Hepatoma Cells ◽  
Proteolytic Activation

Tissue factor (TF) is a lipoprotein cofactor that markedly enhances the proteolytic activation of factors IX and X by factor VIIa. The functional activity of TF is inhibited by serum in a time- and temperature-dependent fashion. The inhibitory effect is also dependent on the presence of calcium ions and can be reversed by calcium chelation (EDTA) and dilution, thus excluding direct proteolytic destruction of TF as the mechanism for inhibition. Using crude TF, serum immunodepleted of factor VII, and serum depleted of the vitamin K- dependent coagulation factors by BaSO4 absorption, it is shown that TF factor inhibition requires the presence of VII(a), X(a), and an additional moiety contained in barium-absorbed serum. When each of the other required components were at saturating concentrations, half- maximal inhibition of TF occurred in reaction mixtures containing 2% (vol/vol) of TF at a factor VII(a) concentration of 4 ng/mL (80 pmol/L), a factor X concentration of 50 ng/mL (850 pmol/L), and a concentration of barium-absorbed serum of 2.5% (vol/vol). Catalytically active factor Xa appeared to be required for the generation of optimal TF inhibition. The results are consistent with the conclusions of Hjort that barium-absorbed serum contains a moiety that inhibits the VIIa- Ca2+-TF complex. The role of factor X(a) in the generation of the inhibitory phenomenon remains to be elucidated. The inhibitor present in serum (plasma) may in part be produced by the liver in vivo since cultured human hepatoma cells (HepG2) secrete this inhibitory activity in vitro.

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