scholarly journals Dose-dependent antithrombotic effect of warfarin in rabbits

Blood ◽  
1983 ◽  
Vol 61 (3) ◽  
pp. 435-438 ◽  
Author(s):  
SN Gitel ◽  
S Wessler
Keyword(s):  
Vitamin K ◽  
Coagulation Factors ◽  
Progressive Increase ◽  
Drug Dose ◽  
Mean Value ◽  
Factor X ◽  
Antithrombotic Effect ◽  
Tissue Thromboplastin ◽  
Dose Dependent Decrease ◽  
Dose Dependent

Abstract One-hundred and fifty-one rabbits, divided into controls and animals treated with varying daily doses of warfarin, were subjected to the stasis assay, and the amount of thrombosis quantitated after intravascular coagulation was initiated either by activated factor X or tissue thromboplastin. Following 8–10 days of warfarin administration, there was a significant dose-dependent decrease in the vitamin-K- dependent coagulation factors paralleled by an increase in the prothrombin time ratio. Whether thrombosis was initiated by activated factor X or tissue thromboplastin, there was, with increasing drug dose, a progressive increase in the inhibition of stasis thrombosis. This significant antithrombotic effect occurred even when the vitamin-K- dependent coagulation activities were at a mean value of 50%.

scholarly journals Dose-dependent antithrombotic effect of warfarin in rabbits

Blood ◽  
1983 ◽  
Vol 61 (3) ◽  
pp. 435-438
Author(s):  
SN Gitel ◽  
S Wessler
Keyword(s):  
Vitamin K ◽  
Coagulation Factors ◽  
Progressive Increase ◽  
Drug Dose ◽  
Mean Value ◽  
Factor X ◽  
Antithrombotic Effect ◽  
Tissue Thromboplastin ◽  
Dose Dependent Decrease ◽  
Dose Dependent

One-hundred and fifty-one rabbits, divided into controls and animals treated with varying daily doses of warfarin, were subjected to the stasis assay, and the amount of thrombosis quantitated after intravascular coagulation was initiated either by activated factor X or tissue thromboplastin. Following 8–10 days of warfarin administration, there was a significant dose-dependent decrease in the vitamin-K- dependent coagulation factors paralleled by an increase in the prothrombin time ratio. Whether thrombosis was initiated by activated factor X or tissue thromboplastin, there was, with increasing drug dose, a progressive increase in the inhibition of stasis thrombosis. This significant antithrombotic effect occurred even when the vitamin-K- dependent coagulation activities were at a mean value of 50%.

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.

scholarly journals Importance of platelets in experimental venous thrombosis in the rat

Blood ◽  
1992 ◽  
Vol 80 (9) ◽  
pp. 2281-2286 ◽  
Author(s):  
JM Herbert ◽  
A Bernat ◽  
JP Maffrand
Keyword(s):  
Venous Thrombosis ◽  
Thrombus Formation ◽  
Vena Cava ◽  
Progressive Increase ◽  
High Dose ◽  
Experimental Conditions ◽  
Dependent Inhibition ◽  
Dose Dependent Inhibition ◽  
Tissue Thromboplastin ◽  
Dose Dependent

Abstract Venous thrombosis was induced by ligature of the inferior vena cava in rats whose blood was made hypercoagulable by intravenous (IV) administration of tissue thromboplastin. From a dose-response showing that the administration of increasing doses of tissue thromboplastin resulted in a subsequent progressive increase of thrombus weight, two concentrations of tissue thromboplastin were chosen: a high dose (550 microL/kg, IV) where thrombus formation was optimal and a concentration (7 microL/kg, IV) where tissue thromboplastin-hypercoagulability was intermediate. In both experimental conditions, leukopenia provoked by a myelotoxic drug did not influence the development of venous thrombosis. However, after thrombocytopenia induced by an antiplatelet antiserum, a dramatic decrease in thrombus formation was observed in animals that had been pre-challenged with the lower dose of tissue thromboplastin, whereas decrease in platelet count did not affect venous thrombosis under high thrombogenic challenge. When administered orally 2 hours before thrombosis induction, the ticlopidine analogue clopidogrel showed dose-dependent inhibition of thrombus formation in animals that were pre-challenged with a low dose of tissue thromboplastin (ED50 = 7.9 +/- 1.5 mg/kg, orally) but remained ineffective against high tissue thromboplastin-induced venous thrombosis. We further determined the effect of heparin and hirudin, and showed that both of these drugs exhibited a more potent antithrombotic activity after injection of the lower dose of tissue thromboplastin than after injection of a high dose of tissue thromboplastin. Therefore, using our model of stasis and hypercoagulability, platelet activation played a major role in the development of venous thrombosis when the thrombogenitic stimulus was mild.

Measuring tissue factor (factor III) activity in plasma.

1989 ◽  
Vol 35 (9) ◽  
pp. 1897-1900 ◽  
Author(s):  
C Fukuda ◽  
K Iijima ◽  
K Nakamura
Keyword(s):  
Tissue Factor ◽  
Disseminated Intravascular Coagulation ◽  
Coagulation Factors ◽  
High Plasma ◽  
Mean Value ◽  
Chromogenic Substrate ◽  
Intravascular Coagulation ◽  
Endogenous Inhibitors ◽  
Tissue Thromboplastin ◽  
The Mean

Abstract This is a method for measuring tissue factor (TF, Factor III, tissue thromboplastin) activity in plasma by using a chromogenic substrate. As pretreatment, the euglobulin fraction of plasma was prepared by removing endogenous inhibitors and heated at 60 degrees C for 3 min to remove fibrinogen. This allowed us to measure the low TF activity in plasma that could not otherwise be measured. Neither phospholipids nor coagulation factors VII, IX, X, or Xa in the samples interfere. Within-run and day-to-day reproducibility were both good. The mean value obtained by this method for normal persons was 1.02 (SD 0.91) arbitrary units/L. A markedly high plasma TF activity of 20 arb. units/L or more was observed in patients with some types of disseminated intravascular coagulation.

scholarly journals Reduction of salivary tissue factor (thromboplastin) activity by warfarin therapy

Blood ◽  
1979 ◽  
Vol 53 (3) ◽  
pp. 366-374 ◽  
Author(s):  
LR Zacharski ◽  
R Rosenstein
Keyword(s):  
Tissue Factor ◽  
Vitamin K ◽  
Coagulation Factors ◽  
Human Saliva ◽  
Factor Vii ◽  
Clotting Factor ◽  
Activate Factor ◽  
Total Protein Content ◽  
Factor X ◽  
Clotting Factors

Abstract The coagulant of normal human saliva has been identified as tissue factor (thromboplastin, TF) by virtue of its ability to cause rapid coagulation in plasmas deficient in first-stage coagulation factors and to activate factor x in the presence of factor VII and by virtue of the fact that its activity is expressed only in the presence of factor VII and is inhibited by an antibody to TF. The TF is related to cells and cell fragments in saliva. Salivary TF activity has been found to be significantly reduced in patients taking warfarin. The decline in TF activity during induction of warfarin anticoagulation occurs during the warfarin-induced decline in vitamin-K-dependent clotting factor activity, as judged by the prothrombin time. The decrease in TF activity is not related to a reduction in salivary cell count or total protein content or to a direct effect of warfarin on the assay. It is hypothesized that the mechanism by which warfarin inhibits TF activity may be related to the mechanism by which it inhibits expression of the activity of the vitamin-K-dependent clotting factors. Inhibition of the TF activity may be involved in the antithrombotic effect of warfarin.

An Assay of the Antithrombotic Action of Warfarin: Its Correlation with the Inhibition of Stasis Thrombosis in Rabbits

1978 ◽  
Vol 40 (02) ◽  
pp. 486-498 ◽  
Author(s):  
Stanford Wessler ◽  
Sanford N Gitel ◽  
Harry Bank ◽  
Uri Martinowitz ◽  
Ronald C Stephenson
Keyword(s):  
Venous Thrombosis ◽  
Vitamin K ◽  
Inhibitory Activity ◽  
Reaction Rate ◽  
Antithrombin Iii ◽  
Factor Ix ◽  
Factor X ◽  
Similar Increase ◽  
Antithrombotic Effect ◽  
And Control

SummaryNo assay of the antithrombotic action of warfarin has been available. Experiments were performed to determine whether Xa inhibitory activity - the reaction rate between activated factor X (Xa) and antithrombin III - could serve this function. 105 warfarin-treated patients demonstrated a significant 18% increase in Xa inhibitory activity compared to 51 controls, p <0.001, without any correlation between this activity and the prothrombin times in the treated patients. A similar increase in Xa inhibitory activity was obtained in rabbits treated with 2 mg of warfarin per day compared to control animals, p <0.001. Employing an assay which routinely produced venous thrombosis after clotting proteases were infused into warfarin-treated and control rabbits, three observations were made. 1. The extent of stasis thrombosis induced by injection of thrombin, Xa or activated factor IX, was significantly reduced in warfarin-treated rabbits compared to control animals, independent of alteration in the four established vitamin K-dependent zymogens. 2. In the rabbit, significant changes in prothrombin times and prothrombin and factor X activities preceded by 5 days both the increase in Xa inhibitory activity and the antithrombotic effect which became significant on the sixth day. 3. The correlation between Xa inhibitory activity of warfarin-treated rabbits and the extent of stasis thrombosis induced by Xa was significant, p<0.05. Xa inhibitory activity is one measure of the antithrombotic action of warfarin.

International Normalized Ratio Versus Plasma Levels of Coagulation Factors in Patients on Vitamin K Antagonist Therapy

2011 ◽  
Vol 135 (4) ◽  
pp. 490-494 ◽  
Author(s):  
Gene Gulati ◽  
Megan Hevelow ◽  
Melissa George ◽  
Eric Behling ◽  
Jamie Siegel
Keyword(s):  
Vitamin K ◽  
Warfarin Therapy ◽  
Clinical Laboratory ◽  
Coagulation Factor ◽  
Coagulation Factors ◽  
International Normalized Ratio ◽  
Activity Levels ◽  
Factor X ◽  
Life Threatening ◽  
Average Factor

Abstract Context.—The key question when managing patients on warfarin therapy who present with life-threatening bleeding is how to use the international normalized ratio (INR) to best direct corrective therapy. The corollary question for the clinical laboratory is at what level will the INR reflect a critical value that requires notifying the clinician. Objective.—To determine the levels of vitamin K–dependent factors over a range of INR values. Design.—Evaluation of the vitamin K–dependent coagulation factor levels on plasma remnants from patients in whom a prothrombin time and INR was ordered to monitor warfarin therapy. There were a total of 83 specimens evaluated with an INR range from 1.0 to 8.26. Results.—The mean activity levels of all 4 factors remained near or above 50% when the INR was less than 1.5. The average factor X level was 23% when the INR range was 1.6 to 2.5, but levels of factors II, VII, and IX did not drop below the hemostatic range until the INR was greater than 2.5. At an INR of 3.6 or more, the activity levels of all 4 factors were less than 30% in more than 90% of the specimens. Conclusion.—Levels of factors II, VII, IX, and X declined with increasing INR but not at the same rate and not to the same level at a given INR. However, most of the values were below the hemostatic value once the INR was 3.6 or more, the level that was also considered critical for physician notification.

GLA-CONTAINING PROTEINS FROM CALCIFIED HUMAN ATHEROSCLEROTIC PLAQUES

1987 ◽  
Author(s):  
L J M Van Haarlem ◽  
H C Hemker ◽  
B A M Soute ◽  
C Vermeer
Keyword(s):  
Vitamin K ◽  
Vessel Wall ◽  
High Performance ◽  
Gel Filtration ◽  
Coagulation Factors ◽  
Atherosclerotic Plaques ◽  
Factor X ◽  
Carboxylase Activity

Vitamin K-dependent carboxylase activity has been detected in human andbovine vessel wall. Studies comparingthe carboxylases from liver and vessel wall revealed that the enzyme systems may be regarded as isoenzymes withwidely different substrate specificities. The carboxylated product of vessel wall carboxylase has not yet been identified, but it seems plausible that it will be found amongst the Gla-containing proteins which are abundantly present in calcified atherosclerotic plaques (Gla= gammacarboxyglutamicacid, the abnormal amino acid formed by vitamin K-dependent carboxylase). Therefore we have started to characterize the protein constituents of hardened atherosclerotic plaques.The calcified areas from human aortae were solubilized in EDTA and the proteins extracted were partly purified by batch-wise adsorption onto QAE and elution with high salt. The crudeplaque-extract did not contain prothrombin, factor X or protein C. This excludes the possibility that Gla-containing coagulation factors are bound non-specifically from blood. Osteocalcin accounted for 20% of the total amount of protein-bound Gla-residues.Another Gla-containing protein waspurified from the crude plaque-extract by employing high performance liquid chromatography (HPLC). Gel filtration yielded a Gla-rich protein with anapparent Mr of 25 kD. In vitro boththe crude plaque-extract and the purified Gla-containing protein strongly inhibited the precipitation of calcium phosphate and calcium carbonate. A similar effect was not found with humanserum albumin nor with a thermallydecarboxylated plaque-extract. If also in vivo the Gla-containing proteinsproduced by vessel wall carboxylase prevent the precipitation of calcium salts remains to be investigated.

scholarly journals Reduction of salivary tissue factor (thromboplastin) activity by warfarin therapy

Blood ◽  
1979 ◽  
Vol 53 (3) ◽  
pp. 366-374 ◽  
Author(s):  
LR Zacharski ◽  
R Rosenstein
Keyword(s):  
Tissue Factor ◽  
Vitamin K ◽  
Coagulation Factors ◽  
Human Saliva ◽  
Factor Vii ◽  
Clotting Factor ◽  
Activate Factor ◽  
Total Protein Content ◽  
Factor X ◽  
Clotting Factors

The coagulant of normal human saliva has been identified as tissue factor (thromboplastin, TF) by virtue of its ability to cause rapid coagulation in plasmas deficient in first-stage coagulation factors and to activate factor x in the presence of factor VII and by virtue of the fact that its activity is expressed only in the presence of factor VII and is inhibited by an antibody to TF. The TF is related to cells and cell fragments in saliva. Salivary TF activity has been found to be significantly reduced in patients taking warfarin. The decline in TF activity during induction of warfarin anticoagulation occurs during the warfarin-induced decline in vitamin-K-dependent clotting factor activity, as judged by the prothrombin time. The decrease in TF activity is not related to a reduction in salivary cell count or total protein content or to a direct effect of warfarin on the assay. It is hypothesized that the mechanism by which warfarin inhibits TF activity may be related to the mechanism by which it inhibits expression of the activity of the vitamin-K-dependent clotting factors. Inhibition of the TF activity may be involved in the antithrombotic effect of warfarin.

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