scholarly journals Extensive Variation in the Activities of Pseudocerastes and Eristicophis Viper Venoms Suggests Divergent Envenoming Strategies Are Used for Prey Capture

Toxins ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 112
Author(s):  
Bianca op den Brouw ◽  
Francisco C. P. Coimbra ◽  
Lachlan A. Bourke ◽  
Tam Minh Huynh ◽  
Danielle H. W. Vlecken ◽  
...  
Keyword(s):  
Prey Capture ◽  
Anticoagulant Activity ◽  
Protein Composition ◽  
Coagulation Factors ◽  
Arid Environments ◽  
Factor X ◽  
Venom Protein ◽  
Research Attention ◽  
Future Assessment ◽  
Viper Venoms

Snakes of the genera Pseudocerastes and Eristicophis (Viperidae: Viperinae) are known as the desert vipers due to their association with the arid environments of the Middle East. These species have received limited research attention and little is known about their venom or ecology. In this study, a comprehensive analysis of desert viper venoms was conducted by visualising the venom proteomes via gel electrophoresis and assessing the crude venoms for their cytotoxic, haemotoxic, and neurotoxic properties. Plasmas sourced from human, toad, and chicken were used as models to assess possible prey-linked venom activity. The venoms demonstrated substantial divergence in composition and bioactivity across all experiments. Pseudocerastes urarachnoides venom activated human coagulation factors X and prothrombin and demonstrated potent procoagulant activity in human, toad, and chicken plasmas, in stark contrast to the potent neurotoxic venom of P. fieldi. The venom of E. macmahonii also induced coagulation, though this did not appear to be via the activation of factor X or prothrombin. The coagulant properties of P. fieldi and P. persicus venoms varied among plasmas, demonstrating strong anticoagulant activity in the amphibian and human plasmas but no significant effect in that of bird. This is conjectured to reflect prey-specific toxin activity, though further ecological studies are required to confirm any dietary associations. This study reinforces the notion that phylogenetic relatedness of snakes cannot readily predict venom protein composition or function. The significant venom variation between these species raises serious concerns regarding antivenom paraspecificity. Future assessment of antivenom is crucial.

A GENERAL MECHANISM FOR LUPUS ANTICOAGULANTS

1987 ◽  
Author(s):  
V Pengo ◽  
M J Heine ◽  
P Thiagarajan ◽  
s s Shapiro
Keyword(s):  
Lupus Anticoagulant ◽  
Anticoagulant Activity ◽  
Protein A ◽  
Coagulation Factors ◽  
Phosphatidyl Serine ◽  
General Mechanism ◽  
Factor X ◽  
Lupus Anticoagulants ◽  
Calcium Dependent ◽  
Anionic Phospholipids

Although- a number of observations have implied that lupus anticoagulants have immunologic specificity towards anionic. phospholipids, thereby prolonging phospholipid-dependent coagulation tests, this assumption has been directly demonstrated in only one patient with a monoclonal IgM paraprotein. We have tested the generality of this hypothesis directly by isolating five IgG lupus anticoagulants from patients with lupus-like syndromes and/or thrombosis. IgG lupus anticoagulant fractions were isolated free of other plasma proteins and free of contaminating phospholipid by adsorption to and elution from cardiolipin-cholesterol-dicetylphosphate liposomes , followed by chromatography on protein A-Sepharose. Cardiolipin liposomes, but not phosphatidylcholine liposomes, were capable of removing all, or nearly all, lupus anticoagulant activity from patient plasma. Anticardiolipin and lupus anticoagulant activity were both present in acidic fractions on isoelectric focusing. F(ab’)2 fragments retained lupus anti coagulant activity and bound to cardiolipin in an ELISA assay. The affinity-purified IgG preparations reacted with cardiolipin, phosphatidyl serine , phosphatidylinositol and phosphatidic acid, but not with phosphatidylcholine or phosphatidyl ethanol amine, and inhibited calcium-dependent binding of prothrombin and of factor X to phosphatidy1serine-coated surfaces. These data demonstrate a general mechanism for the action of lupus anticoagulants: antibodies that have immunologic specificity towards anionic phospholipids, thereby blocking the calcium-mediated binding of vitamin K-dependent coagulation factors to coagulation-active phospholipid surfaces.

scholarly journals Immunological specificity and mechanism of action of IgG lupus anticoagulants

Blood ◽  
1987 ◽  
Vol 70 (1) ◽  
pp. 69-76 ◽  
Author(s):  
V Pengo ◽  
P Thiagarajan ◽  
SS Shapiro ◽  
MJ Heine
Keyword(s):  
Lupus Anticoagulant ◽  
Anticoagulant Activity ◽  
Protein A ◽  
Coagulation Factors ◽  
Enzyme Linked Immunosorbent Assay ◽  
Factor X ◽  
Lupus Anticoagulants ◽  
Calcium Dependent ◽  
Anionic Phospholipids ◽  
Coated Surfaces

Although observations have implied that lupus anticoagulants have immunologic specificity toward anionic phospholipids, this assumption has been directly demonstrated in only one patient with a monoclonal IgM paraprotein. We tested the generality of this hypothesis directly by isolating five IgG lupus anticoagulants from patients with lupuslike syndromes and/or thrombosis. IgG lupus anticoagulant fractions were isolated free of other plasma proteins and free of contaminating phospholipid by adsorption to and elution from cardiolipin-cholesterol- dicetyl phosphate liposomes, followed by chromatography on protein A- Sepharose. Cardiolipin liposomes, but not phosphatidylcholine liposomes, were capable of removing all, or nearly all, lupus anticoagulant activity from patient plasma. The affinity-purified IgG preparations reacted with cardiolipin, phosphatidylserine, phosphatidylinositol, and phosphatidic acid, but not with phosphatidylcholine or phosphatidylethanolamine, and inhibited calcium- dependent binding of prothrombin and of factor X to phosphatidylserine- coated and to cardiolipin-coated surfaces. F(ab')2 fragments retained lupus anticoagulant activity and bound to cardiolipin in an enzyme- linked immunosorbent assay (ELISA). Anticardiolipin and lupus anticoagulant activity were both present in acidic fractions on isoelectric focusing. These data strongly suggest that most, if not all, lupus anticoagulants are antibodies that have immunologic specificity towards anionic phospholipids, thereby blocking the calcium- mediated binding of vitamin K-dependent coagulation factors to coagulation-active phospholipid surfaces.

scholarly journals Immunological specificity and mechanism of action of IgG lupus anticoagulants

Blood ◽  
1987 ◽  
Vol 70 (1) ◽  
pp. 69-76 ◽  
Author(s):  
V Pengo ◽  
P Thiagarajan ◽  
SS Shapiro ◽  
MJ Heine
Keyword(s):  
Lupus Anticoagulant ◽  
Anticoagulant Activity ◽  
Protein A ◽  
Coagulation Factors ◽  
Enzyme Linked Immunosorbent Assay ◽  
Factor X ◽  
Lupus Anticoagulants ◽  
Calcium Dependent ◽  
Anionic Phospholipids ◽  
Coated Surfaces

Abstract Although observations have implied that lupus anticoagulants have immunologic specificity toward anionic phospholipids, this assumption has been directly demonstrated in only one patient with a monoclonal IgM paraprotein. We tested the generality of this hypothesis directly by isolating five IgG lupus anticoagulants from patients with lupuslike syndromes and/or thrombosis. IgG lupus anticoagulant fractions were isolated free of other plasma proteins and free of contaminating phospholipid by adsorption to and elution from cardiolipin-cholesterol- dicetyl phosphate liposomes, followed by chromatography on protein A- Sepharose. Cardiolipin liposomes, but not phosphatidylcholine liposomes, were capable of removing all, or nearly all, lupus anticoagulant activity from patient plasma. The affinity-purified IgG preparations reacted with cardiolipin, phosphatidylserine, phosphatidylinositol, and phosphatidic acid, but not with phosphatidylcholine or phosphatidylethanolamine, and inhibited calcium- dependent binding of prothrombin and of factor X to phosphatidylserine- coated and to cardiolipin-coated surfaces. F(ab')2 fragments retained lupus anticoagulant activity and bound to cardiolipin in an enzyme- linked immunosorbent assay (ELISA). Anticardiolipin and lupus anticoagulant activity were both present in acidic fractions on isoelectric focusing. These data strongly suggest that most, if not all, lupus anticoagulants are antibodies that have immunologic specificity towards anionic phospholipids, thereby blocking the calcium- mediated binding of vitamin K-dependent coagulation factors to coagulation-active phospholipid surfaces.

The Anticoagulant Properties of a Modified Form of Protein S

1988 ◽  
Vol 60 (02) ◽  
pp. 298-304 ◽  
Author(s):  
C A Mitchell ◽  
S M Kelemen ◽  
H H Salem
Keyword(s):  
Monoclonal Antibody ◽  
Anticoagulant Activity ◽  
Activated Protein C ◽  
Factor Xa ◽  
Protein S ◽  
Human Neutrophil Elastase ◽  
Factor X ◽  
Sds Page

SummaryProtein S (PS) is a vitamin K-dependent anticoagulant that acts as a cofactor to activated protein C (APC). To date PS has not been shown to possess anticoagulant activity in the absence of APC.In this study, we have developed monoclonal antibody to protein S and used to purify the protein to homogeneity from plasma. Affinity purified protein S (PSM), although identical to the conventionally purified protein as judged by SDS-PAGE, had significant anticoagulant activity in the absence of APC when measured in a factor Xa recalcification time. Using SDS-PAGE we have demonstrated that prothrombin cleavage by factor X awas inhibited in the presence of PSM. Kinetic analysis of the reaction revealed that PSM competitively inhibited factor X amediated cleavage of prothrombin. PS preincubated with the monoclonal antibody, acquired similar anticoagulant properties. These results suggest that the interaction of the monoclonal antibody with PS results in an alteration in the protein exposing sites that mediate the observed anticoagulant effect. Support that the protein was altered was derived from the observation that PSM was eight fold more sensitive to cleavage by thrombin and human neutrophil elastase than conventionally purified protein S.These observations suggest that PS can be modified in vitro to a protein with APC-independent anticoagulant activity and raise the possibility that a similar alteration could occur in vivo through the binding protein S to a cellular or plasma protein.

The Influence of the Thyroid Function on the Metabolic Rate of Prothrombin, Factor VII, and Factor X in the Rat

1976 ◽  
Vol 35 (03) ◽  
pp. 607-619 ◽  
Author(s):  
Allan T. van Oosterom ◽  
Herman Mattie ◽  
Wim Th Hermens ◽  
Jan J. Veltkamp
Keyword(s):  
Metabolic Rate ◽  
Thyroid Function ◽  
Coagulation Factors ◽  
Biologically Active ◽  
Factor Vii ◽  
Synthesis Rate ◽  
Apparent Difference ◽  
Vitamin K1 ◽  
Factor X ◽  
Significant Difference

SummaryThe influence of the thyroid function on the metabolic rate of prothrombin, factor VII, and X was studied in the rat. Disappearance rates of the three coagulation factors were measured after synthesis had been blocked with appropriate doses of warfarin, and reappearance rates were assessed upon induction of synthesis by high doses of vitamin K1 injected into rats displaying coumarin induced hypocoagulability.No statistically significant difference in the disappearance and production rates of any of the factors could be found between normal euthyroid rats and thyroxin-treated hypothyroid rats proven to be euthyroid. The differences between the two euthyroid groups and the hypothyroid group were highly significant, however: hypothyroidism results in an approximately 50% decrease of the metabolic rates of the three coagulation factors under study.The reappearance of the three factors, under euthyroid as well as hypothyroid conditions, showed a biphasic pattern: in the first two hours after vitamin K1 administration to warfarin treated rats, a rapid reappearance was observed, to the same extent for all three factors, in hypo- as well as euthyroid rats. This finding suggests that in vitamin K1 deficiency an intracellular accumulation of precursor proteins (PIVKAs) occurs, which after rapid conversion into biologically active coagulation factors by vitamin K1 are shed into circulation.The subsequent phase of reappearance is much slower and reflects the synthesis rate of coagulation enzymes. It is characteristic for each factor and clearly slower in hypothyroid rats than in euthyroid rats. From this an influence of thyroid function on the synthesis rate of the protein moiety of coagulation factors can be inferred.An apparent difference between disappearance and reappearance rate of the coagulation factors in the plasma, particularly pronounced for factors VII and X in euthyroid rats, could theoretically be explained as the consequence of the model used for derivation of these rates.

Increased Activity of Vitamin K-Dependent Clotting Factors in Human Hyperlipoproteinaemia – Association with Cholesterol and Triglyceride Levels

1977 ◽  
Vol 38 (02) ◽  
pp. 0465-0474 ◽  
Author(s):  
M Constantino ◽  
C Merskey ◽  
D. J Kudzma ◽  
M. B Zucker
Keyword(s):  
Vitamin K ◽  
Plasma Lipids ◽  
Coagulation Factors ◽  
Clotting Factor ◽  
Factor X ◽  
Clotting Factors ◽  
Blood Coagulation Factors ◽  
Cholesterol Levels ◽  
Type V ◽  
Increased Activity

SummaryLevels of blood coagulation factors, cholesterol and triglyceride were measured in human plasma. Prothrombin was significantly elevated in type Ha hyperlipidaemia; prothrombin and factors VII, IX and X in type lib; and prothrombin and factors VII and IX in type V. Multiple regression analysis showed significant correlation between the levels of these plasma lipids and the vitamin K-dependent clotting factors (prothrombin, factors VII, IX and X). Higher cholesterol levels were associated with higher levels of prothrombin and factor X while higher triglyceride levels were associated with higher levels of these as well as factors VII and IX. Prothrombin showed a significant cholesterol-triglyceride interaction in that higher cholesterol levels were associated with higher prothrombin levels at all levels of triglyceride, with the most marked effects in subjects with higher triglyceride levels. Higher prothrombin levels were noted in subjects with high or moderately elevated (but not low) cholesterol levels. Ultracentrifugation of plasma in a density of 1.21 showed activity for prothrombin and factors VII and X only in the lipoprotein-free subnatant fraction. Thus, a true increase in clotting factor protein was probably present. The significance of the correlation between levels of vitamin K-dependent clotting factors and plasma lipids remains to be determined.

Clinical Information From Screening Programs For Coagulation And Fibrinolytic Factors And Inhibitor Deficiencies Using Automated Chromogenic Methods

1981 ◽  
Author(s):  
J W ten Cate ◽  
L H Kahlé ◽  
H R Büller ◽  
M Peters ◽  
G H Weenink
Keyword(s):  
Oral Anticoagulant Therapy ◽  
Venous Blood ◽  
Postoperative Bleeding ◽  
Clinical Information ◽  
Coagulation Factors ◽  
Normal Pregnancy ◽  
Factor X ◽  
Gram Negative ◽  
Screening Programs ◽  
At Iii

The introduction of chromogenic substrates allowed the development of automated spectophotometric assays. After having developed such methods employing an automated kinetic enzyme and substrate analyser for coagulation factors II and X, antithrombin III (AT III), plasminogen (PG) and α2- antiplasmin (α2-AP) , we decided to apply these methods in well defined clinical projects in order to evaluate their future clinical potency. Results obtained thusfar revealed that 1. AT III and PG are predictors of gram negative septicaemia in patients with intraabdominal infection following major abdominal and vascular surgery, 2. The predictive value of AT III for gram negative septicaemia in prospective studies in premature neonates (all assays require only 0.4 ml of venous blood), 3. AT III remains unchanged in normal pregnancy. Decreasing values are observed in toxaemia and isolated deficiencies are observed as an early sign of intravascular coagulation in pre- ecclampsia, 4. Routine screening of AT III in female subjects on oral anticonceptive drugs is of no use, 5. Factor X assays may possibly be used for the control of oral anticoagulant therapy, 6. Screening of patients with postoperative bleeding disorders may disclose congenital factor X deficiency not reflected by routine prothrombin time measurements.

scholarly journals In Hemophilia Α Plasma Treated with Emicizumab, Factor IXa in Activated Prothrombin Complex Concentrates Is the Dominant Contributor to Enhanced Thrombin Generation

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 16-17
Author(s):  
Dougald Monroe ◽  
Mirella Ezban ◽  
Maureane Hoffman
Keyword(s):  
Thrombin Generation ◽  
Hemophilia A ◽  
State Level ◽  
Peak Level ◽  
Coagulation Factors ◽  
Major Effect ◽  
Factor Ix ◽  
Factor X ◽  
Factor Ixa ◽  
Activated Prothrombin Complex Concentrates

Background. Recently a novel bifunctional antibody (emicizumab) that binds both factor IXa and factor X has been used to treat hemophilia A. Emicizumab has proven remarkably effective as a prophylactic treatment for hemophilia A; however there are patients that still experience bleeding. An approach to treating this bleeding in hemophilia A patients with inhibitors is to give an activated prothrombin complex concentrate (APCC; FEIBA) (disfavored in NHF MASAC #255). APCC contains a number of coaguation factors including prothrombin, factor X (FX), and factor IX (FIX). APCC also contains activated factor X (FXa) and factor IX (FIXa). Previous work has shown that when APCCs are added to hemophilia A plasma containing emicizumab there is a significant increase in thrombin generation [J Thromb Haemost 2018;16:1580-1591]. The goal of this work was to study thrombin generation in hemophilia A plasma with emicizumab and to examine the role of the zymogen and activated components of an APCC in the increased thrombin generation. Methods. In hemophilia A plasma, thrombin generation assays were done using 100 µM lipid and 420 µM Z-Gly-Gly-Arg-AMC with or without emicizumab at 55 µg/mL which is the clinical steady state level. The reactions were initiated with low (1 pM) tissue factor (TF). The components of APCC were studied at concentrations that should mimic the levels seen in the plasma of a patient given a dose of 50 U/kg: prothrombin 1800 nM; FX 130 nM; FIX 90 nM; and FIXa 0.4 nM. Results. When initiated with low TF, hemophilia A plasma alone had essentially no thrombin generation. As expected, adding emicizumab enhanced thrombin generation. The addition of zymogen coagulation factors, prothrombin, FIX, and FX, separately or together gave a small increase in thrombin generation. However, addition of FIXa to emicizumab gave a large increase in peak thrombin. In hemophilia A plasma with emicizumab and FIXa, addition of prothrombin further increased thrombin generation and specifically increased the peak level of thrombin. Further addition of FX or FIX, separately or together, only minimally increased thrombin generation. Discussion. The strong contribution of factor IXa to the effects of APCCs on thrombin generation in hemophilia A plasma depends on the presence of emicizumab. In the absence of emicizumab, a study of the individual components of APCC showed that a combination of FXa and prothrombin at levels found in APCCs had the major effect on thrombin generation [Haemophilia. 2016;22:615-24]. That study found that FIXa did not increase thrombin generation. However, in the presence of emicizumab, despite the weak solution phase affinity of the bifunctional antibody for FIXa, small amounts of FIXa were the most significant contributor to thrombin generation. Disclosures Monroe: Novo Nordisk:Research Funding.Ezban:Novo Nordisk:Current Employment.Hoffman:Novo Nordisk:Research Funding.

scholarly journals Evidence for the presence of tissue factor activity on subendothelium

Blood ◽  
1989 ◽  
Vol 73 (4) ◽  
pp. 968-975
Author(s):  
HJ Weiss ◽  
VT Turitto ◽  
HR Baumgartner ◽  
Y Nemerson ◽  
T Hoffmann
Keyword(s):  
Tissue Factor ◽  
Umbilical Artery ◽  
Factor Viia ◽  
Rabbit Aorta ◽  
Coagulation Factors ◽  
Factor Vii ◽  
Factor X ◽  
Factor Activity ◽  
Fibrin Deposition ◽  
Tissue Factor Activity

By a variety of methods, tissue factor activity was demonstrated in the subendothelium of rabbit aorta and human umbilical artery. In one method, everted segments of de-endothelialized vessels were mounted in an annular perfusion chamber and the subendothelial surface was exposed to nonanticoagulated human blood under controlled flow. Procoagulant activity was assessed by measuring fibrin deposition on subendothelium and fibrinopeptide A (FPA) levels in post chamber blood. Both fibrin deposition and FPA were decreased with rabbit vessel segments exposed (at a shear rate of 650 seconds-1) to blood from patients with factor VII deficiency and with umbilical artery segments (at shear rates of 90 to 180 seconds-1) that had been pretreated with a monoclonal antibody to human tissue factor. In a second method, everted umbilical artery segments were mounted on a stir bar and the subendothelial surface was exposed, with stirring, to plasma or purified coagulation factors. The capacity of the surface to clot plasma on addition of calcium was inhibited by the antibody to tissue factor. The surface also activated purified 3H-factor X in the presence of factor VIIa, but not in its absence, and this surface property was almost entirely eliminated by pretreating the vessel segments with antitissue factor. Tissue factor activity in subendothelium could play a role in both the arrest of bleeding and in promoting the formation of thrombi at sites of vascular injury.

ABNORMALITIES OF PLATELET AGGREGATION AND ENHANCED FACTOR X ACTIVATOR ACTIVITY OF WASHED PLATELETS IN SICKLE CELL DISEASE

1987 ◽  
Author(s):  
D A F Chamone ◽  
A Y Hoshikawa-Fujimura ◽  
C Massumoto ◽  
G Bellotti ◽  
F Arashiro ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Sickle Cell Disease ◽  
Sickle Cell ◽  
Vascular Endothelium ◽  
Platelet Rich Plasma ◽  
Coagulation Factors ◽  
Factor X ◽  
Cell Disease ◽  
Normal Volunteers ◽  
Pathologic Features

The occurence of microvascular occlusion is one of the most prominent pathologic features of sickle cell anemia. The mechanism of vaso occlusion has generally been attributed to the abnormal shape and reduced deformability of the sickled erithrocy tes. However, the involvement of vascular endothelium, platelets and their interactions with coagulation factors may also be of pathogenic significance in microvascular occlusive crises.We investigated the interaction between vascular endothelium, platelets and blood coagulation factors in 23 patients with Sickle Cell Disease (SCD) and in normal volunteers.Factor X activator activity in washed platelets was performed according to Semeraro and Vermylen (1977), thromboxane B2 (TXB2) and 6-keto-PGF1β were determined using specific radioimmunoassays.. PAF-acether from platelets was determined according to Chignard et al (Nature, 1979, 279:799). Platelet aggregation was performed with a Chrono-Log Aggregometer (Model 440) on platelet rich plasma (PRP) using the Born method. Prostacyclin release from endothelium was performed according to Mon-cada et al (Lancet i:18, 1977).Our results showed that platelets from patients with SCD ha ve enhanced factor X activator activity (p < 0.0001), produce mo re PAF-acether than controls (p < 0.02) and showed hyperaggregability in these patients as compared to normal volunteers (p < 0.00001).We concluded that platelets from homozygous sicklers have enhanced factor X activator activity as well as increased capacity for PAF-acether production. These abnormalities may contribute to the incidence of vaso occlusive crises in these patients.

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