Activated partial thromboplastin time measurements in citrated canine plasma

1992 ◽  
Vol 106 (1) ◽  
pp. 79-82 ◽  
Author(s):  
G.O. Evans ◽  
R.M. Flynn
Keyword(s):  
Partial Thromboplastin Time ◽  
Activated Partial Thromboplastin Time ◽  
Canine Plasma

scholarly journals Activated Partial Thromboplastin Time as a Screening Test of Minor or Moderate Coagulation Factor Deficiencies for Canine Plasma: Sensitivity of Different Commercial Reagents

2000 ◽  
Vol 12 (5) ◽  
pp. 433-437 ◽  
Author(s):  
Reinhard Mischke
Keyword(s):  
Partial Thromboplastin Time ◽  
Screening Test ◽  
Reference Range ◽  
Standardized Test ◽  
Coagulation Factor ◽  
Activated Partial Thromboplastin Time ◽  
Plasma Samples ◽  
Test Protocol ◽  
Different Types ◽  
Canine Plasma

To determine the sensitivity for detection of coagulation factor deficiencies by commercial reagents for canine plasma, 5 commercial activated partial thromboplastin time (APTT) reagents with different types of contact activator and phospholipid of various origin were examined. Thirty canine plasma samples with minor or moderate deficiencies of coagualition factors that influence the APTT were examined. Significant differences were found for the sensitivity of various reagents, but no correlation was found with the type of contact activator. Following the test instructions provided by the manufacturers, the number of APTT results that were prolonged beyond the reference range varied between 20 and 30 (sensitivity = 0.67–1.00); the number of corresponding results using a standardized test protocol varied between 19 and 28 (sensitivity: 0.63–0.93). The most sensitive reagent contained kaolin as a contact activator and a human placental thromboplastin. The results of this study indicate that the APTT test optimized for human plasma is also a sensitive screening test of the intrinsic system of canine plasma, provided that a suitable reagent is used.

Monitoring Heparin Therapy: Relationships between the Activated Partial Thromboplastin Time and Heparin Assays Based on Ex-Vivo Heparin Samples

1990 ◽  
Vol 63 (01) ◽  
pp. 016-023 ◽  
Author(s):  
A M H P van den Bessekaar ◽  
J Meeuwisse-Braun ◽  
R M Bertina
Keyword(s):  
Partial Thromboplastin Time ◽  
Plasma Sample ◽  
Ex Vivo ◽  
Correlation Coefficients ◽  
Heparin Therapy ◽  
Thromboembolic Disease ◽  
Activated Partial Thromboplastin Time ◽  
Venous Thromboembolic Disease ◽  
Venous Thromboembolic

SummaryFive different APTT reagents, two amidolytic anti-ITa assays, one amidoiytic anti-Xa assay, and one coagulometric anti-Xa/ anti-IIa assay were used to assess the effect of heparin in patients treated for venous thromboembolic disease. Good correlations were observed between lug-transformed APYE> determined with the various reagents (correlation coefficients: 0.92-0.96).Nevertheless there were important differences in the slopes of the lines of relationship between the APTT reagents.Good correlations were observed between the anti-Xa and anti-IIa assay results (correlation coefficients: 0.92-0.97). However, the amidolytic anti-Xa activity was significantly higher (p <0.001) than the two amidolytic anti-IIa activities. Less good correlations were observed between the log-transformed APTTs and the anti-Xa or anti-IIa activities (correlation coefficients: 0.64-0.78). The correlations were improved by transforming the APTT into APTT-ratio, i.e. the ratio of the patient’s APTT to the same patient’s APTT after removal of heparin from the plasma sample by means of ECTEOLA-cellulose treatment. The correlation coefficients of log (AFTT-ratio) with anti-Xa or anti-IIa ranged from 0.76 to 0.87.For both APTT and amidolytic heparin assay, the response to in vitro heparin was different from the response to ex vivo heparin.Therefore, equivalent therapeutic ranges should be assessed by using ex vivo samples rather than in vitro heparin. Because of the response differences between the APTT reagents, it is not adequate to define a therapeutic range for heparin therapy without specification of the reagent.

Monitoring Anticoagulant Therapy by Activated Partial Thromboplastin Time: Hirudin Assessment

1994 ◽  
Vol 72 (05) ◽  
pp. 685-692 ◽  
Author(s):  
Michael T Nurmohamed ◽  
René J Berckmans ◽  
Willy M Morriën-Salomons ◽  
Fenny Berends ◽  
Daan W Hommes ◽  
...  
Keyword(s):  
Whole Blood ◽  
Partial Thromboplastin Time ◽  
Ex Vivo ◽  
Fold Increase ◽  
Heparin Therapy ◽  
Activated Partial Thromboplastin Time ◽  
Recombinant Hirudin ◽  
Interindividual Differences ◽  
The Relationship

SummaryBackground. Recombinant hirudin (RH) is a new anticoagulant for prophylaxis and treatment of venous and arterial thrombosis. To which extent the activated partial thromboplastin time (APTT) is suitable for monitoring of RH has not been properly evaluated. Recently, a capillary whole blood device was developed for bed-side monitoring of the APTT and it was demonstrated that this device was suitable to monitor heparin therapy. However, monitoring of RH was not evaluated.Study Objectives. To evaluate in vitro and ex vivo the responsiveness and reproducibility for hirudin monitoring of the whole blood monitor and of plasma APTT assays, which were performed with several reagents and two conventional coagulometers.Results. Large interindividual differences in hirudin responsiveness were noted in both the in vitro and the ex vivo experiments. The relationship between the APTT, expressed as clotting time or ratio of initial and prolonged APTT, and the hirudin concentration was nonlinear. A 1.5-fold increase of the clotting times was obtained at 150-200 ng/ml plasma. However, only a 2-fold increase was obtained at hirudin levels varying from 300 ng to more than 750 ng RH/ml plasma regardless of the assays. The relationship linearized upon logarithmic conversion of the ratio and the hirudin concentration. Disregarding the interindividual differences, and presuming full linearity of the relationship, all combinations were equally responsive to hirudin.Conclusions. All assays were equally responsive to hirudin. Levels up to 300 ng/ml plasma can be reliably estimated with each assay. The manual device may be preferable in situations where rapid availability of test results is necessary.

Inhibition of Coagulation and Fibrinolysis by Aromatic Amidino Compounds

1971 ◽  
Vol 25 (03) ◽  
pp. 391-404 ◽  
Author(s):  
J.D Geratz
Keyword(s):  
Prothrombin Time ◽  
Human Plasma ◽  
Partial Thromboplastin Time ◽  
Inhibitory Effect ◽  
Clot Lysis ◽  
Similar Degree ◽  
Contact Activation ◽  
Plasma Clot ◽  
Human Thrombin ◽  
Canine Plasma

Summary1. Aromatic diamidines which are potent inhibitors of trypsin possess a marked inhibitory effect on the clotting activity of human thrombin and on the prothrombin time and partial thromboplastin time of human plasma. They also block the contact activation phase of the coagulation process. The strongest inhibitor among the compounds tested was M & B 4596 which was followed in second place by pentamidine.2. Pentamidine was 10 times more active than ε-ACA in impeding streptokinase-induced lysis of human plasma clots. It was 100-200 times stronger than ε-ACA in inhibiting the activation of bovine plasminogen by activators formed from the interaction between streptokinase and either human plasmin(ogen) or human plasma.3. The prothrombin time and partial thromboplastin time of canine plasma were less susceptible to inhibition by pentamidine than the same tests on human plasma. Clot lysis in the canine system was inhibited by pentamidine to a similar degree as in the human system. After intravenous injection of pentamidine in the dog there occurred the expected prolongation of the partial thromboplastin time and of the clot lysis time.

In Vitro Thrombogenicity Tests of Factor IX Concentrates

1979 ◽  
Vol 42 (05) ◽  
pp. 1355-1367 ◽  
Author(s):  
C V Prowse ◽  
A Chirnside ◽  
R A Elton
Keyword(s):  
Factor Viii ◽  
Partial Thromboplastin Time ◽  
Generation Time ◽  
Activated Partial Thromboplastin Time ◽  
Factor Ix ◽  
In Vitro Tests ◽  
Factor Viii Inhibitor ◽  
Factor Ixa ◽  
Viii Inhibitor

SummaryVarious factor IX concentrates have been examined in a number of in vitro tests of thrombogenicity. The results suggest that some tests are superfluous as in concentrates with activity in any of these tests activation is revealed by a combination of the non-activated partial thromboplastin time, the thrombin (or Xa) generation time and factor VIII inhibitor bypassing activity tests. Assay of individual coagulant enzymes revealed that most concentrates contained more factor IXa than Xa. However only a small number of concentrates, chiefly those that had been purposefully activated, contained appreciable amounts of either enzyme.

A Comparison of Heparin Potency Estimates Obtained by Activated Partial Thromboplastin Time and British Pharmacopoeial Assays

1985 ◽  
Vol 53 (01) ◽  
pp. 116-117 ◽  
Author(s):  
R E Merton ◽  
A D Curtis ◽  
D P Thomas
Keyword(s):  
United States ◽  
Partial Thromboplastin Time ◽  
Close Agreement ◽  
The United States ◽  
Activated Partial Thromboplastin Time ◽  
United States Pharmacopeia ◽  
International Unit ◽  
British Pharmacopoeia ◽  
States Pharmacopeia ◽  
Heparin Preparation

SummaryHeparin samples from five manufacturers were assayed by the revised British Pharmacopoeia (BP) heparin assay and the results compared with those obtained using the activated partial thromboplastin time (APTT) assay. The United States Pharmacopeia (USP) reference heparin preparation and the 4th International Standard (IS) for heparin were also assayed by the two methods relative to the 3rd IS. The results obtained by the revised BP assay were in close agreement with those obtained by the APTT assay for all the heparins that were tested. The assays revealed that there is at least a 10% discrepancy between the International Unit for heparin and the USP unit.

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