Thromboplastin as a Reagent

1970 ◽  
Vol 23 (03) ◽  
pp. 585-592 ◽  
Author(s):  
A .J Quick
Keyword(s):  
Prothrombin Time ◽  
Oral Anticoagulant Therapy ◽  
Quantitative Measure ◽  
Rabbit Brain ◽  
Bacterial Action ◽  
Normal Human ◽  
Tissue Thromboplastin ◽  
Time Test ◽  
The One ◽  
Evacuated Tube

SummaryTissue thromboplastin is the key reagent in the one-stage prothrombin time test. To obtain reliable results, a potent thromboplastin with constant activity and stability is required. This need is met by acetone-dehydrated rabbit brain. This reagent, when protected against oxidation by sealing in an evacuated tube, retains its full activity indefinitely. The basic prothrombin time serves as a screening test for depletion of prothrombin, factors V, VII and X. Thromboplastin is slowly inactivated by oxidation and also by bacterial action. Phenol prevents the latter reaction and therefore a phenolized extract of either human brain or acetone-dehydrated rabbit brain serves as a satisfactory reagent for the prothrombin time when employed to control oral anticoagulant therapy.The constant 12 sec prothrombin time of fresh normal human plasma is fixed by the concentration of active prothrombin. By modifying the basic prothrombin time by adding excess of factors V, VII or X, the test is made a specific quantitative measure of each of these factors.

Recombinant Tissue Factor as Substitute for Conventional Thromboplastin in the Prothrombin Time Test

1992 ◽  
Vol 67 (01) ◽  
pp. 042-045 ◽  
Author(s):  
Armando Tripodi ◽  
Arnaldo Arbini ◽  
Veena Chantarangkul ◽  
Pier Mannuccio Mannucci
Keyword(s):  
Prothrombin Time ◽  
Tissue Factor ◽  
Oral Anticoagulant Therapy ◽  
Clotting Factor ◽  
Rabbit Brain ◽  
Sensitivity Index ◽  
Clotting Factors ◽  
Wide Range ◽  
Reference Preparation ◽  
Time Test

SummaryRelipidated recombinant tissue factor (r-TF) has been assessed in comparison with conventional rabbit brain thromboplastin (Manchester Reagent) for its suitability for measurement of prothrombin time (PT). The International Sensitivity Index (ISI) of r-TF calibrated against the International Reference Preparation BCT/253 (human plain) was found to be 0.96 and 1.12 with instrumental and manual techniques. Our study of plasmas from patients with congenital deficiencies of clotting factors covering a wide range of severity demonstrates that r-TF is able to detect even minor deficiencies of factors involved in the extrinsic and common coagulation pathways. Patients with liver diseases were correctly diagnosed with a prevalence of abnormal results comparable for both reagents. Between-assay reproducibility expressed as coefficient of variation was 2.3 % and 3.9 % at normal and abnormal PT levels.In conclusion, our evaluation shows that relipidated r-TF possesses the necessary requisites of sensitivity, diagnostic accuracy and reproducibility which make it a suitable candidate for PT determination both for monitoring oral anticoagulant therapy and diagnosing congenital and acquired clotting factor deficiencies. Moreover, being a highly defined reagent it may constitute a step forward in the standardization of PT testing.

Use of Different Tissue Thromboplastins in the Control of Anticoagulant-Therapy

1958 ◽  
Vol 02 (05/06) ◽  
pp. 462-480 ◽  
Author(s):  
Marc Verstraete ◽  
Patricia A. Clark ◽  
Irving S. Wright
Keyword(s):  
Prothrombin Time ◽  
Anticoagulant Therapy ◽  
Factor Vii ◽  
Rabbit Brain ◽  
Minor Role ◽  
Rabbit Lung ◽  
Coagulation Mechanism ◽  
Time Test ◽  
The One ◽  
A Minor

SummaryAn analysis of the results of prothrombin time tests with different types of thromboplastins sheds some light on the problem why the administration of coumarin is difficult to standardize in different centers. Our present ideas on the subject, based on experimental data may be summarized as follows.Several factors of the clotting mechanism are influenced by coumarin derivatives. The action of some of these factors is by-passed in the 1-stage prothrombin time test. The decrease of the prothrombin and factor VII levels may be evaluated in the 1-stage prothrombin time determination (Quick-test). The prolongation of the prothrombin times are, however, predominantly due to the decrease of factor VII activity, the prothrombin content remaining around 50 per cent of normal during an adequate anticoagulant therapy. It is unlikely that this degree of depression of prothrombin is of major significance in interfering with the coagulation mechanism in the protection against thromboembolism. It may, however, play a minor role, which has yet to be evaluated quantitatively. An exact evaluation of factor VII is, therefore, important for the guidance of anticoagulant therapy and the method of choice is the one which is most sensitive to changes in factor VII concentration. The 1-stage prothrombin time test with a rabbit lung thromboplastin seems the most suitable method because rabbit brain preparations exhibit a factor VII-like activity that is not present in rabbit lung preparations.

Anticoagulant Properties of Rabbit Lungs in Tissue Thromboplastin-induced Intravascular Coagulation

1997 ◽  
Vol 77 (04) ◽  
pp. 679-684 ◽  
Author(s):  
Henrik Vad ◽  
Tove F Tvedskov ◽  
Knud B Hansen ◽  
Ole K Albrechtsen ◽  
Jørgen Jespersen ◽  
...  
Keyword(s):  
Prothrombin Time ◽  
Right Atrium ◽  
Blood Platelets ◽  
Rabbit Brain ◽  
Intravascular Coagulation ◽  
Common Trend ◽  
Blood Ph ◽  
First Pass ◽  
Tissue Thromboplastin ◽  
The Right

SummaryThis study was conducted in order to examine possible anticoagulant properties of the lungs during tissue thromboplastin-induced intravascular coagulation. Rabbit brain tissue thromboplastin (n = 17) or saline (n = 6 + 3) was infused above the right atrium (n = 11 + 3) of the heart or in the arcus aorta (n = 6) for a period of 120 min in non-pregnant New Zealand rabbits. Rabbits infused with tissue thromboplastin responded with significantly (p <0.05) more excessive changes in a number of haemodynamic variables (heart rate, paO2> paCO2, blood pH etc.) compared with rabbits infused with saline.Similarly, the prothrombin time (p <0.05) and the activated partial thromboplastin time (p <0.05) were significantly more prolonged in rabbits receiving tissue thromboplastin compared with control animals. Also the concentration of blood platelets (p<0.05), plasma fibrinogen (p <0.05), antithrombin (p <0.05), and protein C (p <0.05) decreased significantly in thromboplastin-treated animals compared with control animals. In all these haemostatic variables there was a common trend that animals infused with tissue thromboplastin in the arcus aorta responded more excessively than animals infused in the right atrium of the heart, and these deviations were statistically significant for fibrinogen (p <0.05) and prothrombin time (p <0.05). Similarly, animals infused with tissue thromboplastin in the arcus aorta had an increased number of microthrombi in the lungs and kidneys compared with animals receiving tissue thromboplastin above the right atrium.As the lungs are the first pass organ when you infuse above the right atrium the results from this study suggest that the lungs play a key role in protecting the organism against excessive tissue thromboplastin-induced activation of coagulation.

ACTIVATION OF FACTOR VII BY ASBESTOS IN BEEF PLASMA AND SERUM

1958 ◽  
Vol 36 (9) ◽  
pp. 953-958 ◽  
Author(s):  
L. G. Israels ◽  
E. Friesen ◽  
C. Sinclair
Keyword(s):  
Prothrombin Time ◽  
Human Plasma ◽  
Factor Vii ◽  
One Stage ◽  
Tissue Thromboplastin ◽  
The One

The adsorption of beef plasma on asbestos markedly shortens the one-stage prothrombin time of the plasma when tissue thromboplastin is used as the throm boplastic agent. This adsorption on asbestos does not affect the Russell viper venom time of the plasma. The adsorbed plasma exhibits increased factor VII activity over that of the original plasma. An eluate can be prepared from the asbestos which prolongs the one-stage prothrombin time sof beef and human plasma.

Factor IX Alloantibodies Shorten the Bovine Thromboplastin Coagulation Time of Normal Human Plasma

1981 ◽  
Vol 46 (04) ◽  
pp. 684-686
Author(s):  
Karen Helene Ørstavik
Keyword(s):  
Prothrombin Time ◽  
Rabbit Antiserum ◽  
Factor Ix ◽  
Hemophilia B ◽  
Antigenic Determinants ◽  
Ability To Act ◽  
Before And After ◽  
Normal Human ◽  
The One ◽  
Control Plasma

SummaryWe have previously demonstrated that neutralization of factor IX in normal plasma by heterologous antisera shortens the one stage prothrombin time determined with bovine thromboplastin. In this study, a similar effect of homologous antibodies was demonstrated. Addition of plasma from two patients with hemophilia B- and an acquired inhibitor to factor IX gave a shortening of the prothrombin time of plasma from normal persons, compared to the prothrombin time determined after addition of control plasma from a patient with hemophilia B- and no inhibitor. Addition of inhibitor plasma had a similar effect on the prothrombin time of plasma from four patients with hemophilia B+ and one patient with hemophilia Br, but had no effect on the prothrombin time of plasma from ten patients with hemophilia B-. Complexes between factor IX and the human inhibitor could be demonstrated both before and after the coagulation with bovine thromboplastin. These complexes were demonstrated as a factor IX antigen with a reduced electrophoretic mobility in crossed immunoelectrophoresis against a rabbit antiserum to factor IX. The results demonstrate that normal factor IX loses the ability to act as an inhibitor in the coagulation with bovine thromboplastin after having formed a soluble complex with a homologous antibody, although the factor IX molecules still have antigenic determinants which are free to react with the rabbit antibodies.

A Novel Chromogenic Assay Equivalent to the One Stage Prothrombin Time (PT)

1979 ◽  
Author(s):  
D. J. Baughman ◽  
A. Lytwyn
Keyword(s):  
Plasma Concentration ◽  
Prothrombin Time ◽  
Thrombin Generation ◽  
Specific Factor ◽  
Exponential Rate ◽  
Factor X ◽  
Chromogenic Assay ◽  
Initial Appearance ◽  
Tissue Thromboplastin ◽  
The One

A chromogenic assay equivalent to the PT has been developed which, it is expected, will allow the standardization of therapeutic limits. Assays were performed by combining 0.25 ml S-2238 (2mM), 0.40 ml tissue thromboplastin, and 0.050 ml plasma in 1.40 ml TRIS buffer (pH=8.50, I=0.15). The rate of thrombin generation was obtained by automatically computing the slope of In (A405nm/min. ) vs time. The results indicated that thromboplastin does not interfere with S-2238 hydrolysis. Thrombin production (A/min.) occurs just before clotting, rises rapidly to a maximum and falls. During its rise, the thrombin concentration increases as a positive exponential, exp(bt). The exponential rate, called b, is constant from the initial appearance to the maximum thrombin concentration, b is proportional to plasma concentration and to log Factor (X, VII, V) concentration for dilutions with deficient plasma. Log 1/b correlates with log PT using dicoumarolized plasmas. Thrombin appearance is quite delayed (12 min.) in diluted, deficient plasma. Thus, the assay appears sensitive to the extrinsic system and can be used to monitor dicoumarolized plasmas. Unlike the standard PT, this assay directly measures the rate of thrombin production and could be standardized by comparing the exponential rate to specific Factor concentrations.

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