An Assessment Of An Amidolytic Assay For Factor VII In The Laboratory Control Of Oral Anticoagulants

1981 ◽  
Author(s):  
A Bodzenta ◽  
Jean M Thomson ◽  
Z S Latallo
Keyword(s):  
Prothrombin Time ◽  
Oral Anticoagulant ◽  
Oral Anticoagulants ◽  
Factor Vii ◽  
Limiting Factor ◽  
Factor X ◽  
Present Evidence ◽  
Chromogenic Assay ◽  
Better Than

An amidolytic assay for factor VII, modified from the method of Seligsohn et al (1978), has been compared with the results of the prothrombin time using British Comparative Thromboplastin, Thronbotest and a clotting assay for factor VII. In ‘long-term’ oral anticoagulant administration agreement with the conventional methods was good and better than in our previous study when amidolytic assays for factors II and X respectively were studied (Latallo et al 1981). The method appeared to be reasonably specific for factor VII.On the present evidence the chromogenic assay for factor VII offers a limited but apparently dependable guide to dosage but it is elaborate to perform and difficult to standardise. The main limiting factor for its routine application is the need to prepare a purified factor X extract.

PROTEIN C RESPONSE TO INDUCTION AND WITHDRAWAL OF ORAL ANTICOAGULANT TREATMENT

1987 ◽  
Author(s):  
K P Schofield ◽  
J M Thomson ◽  
L Poller
Keyword(s):  
Oral Anticoagulant ◽  
Protein C ◽  
Oral Anticoagulants ◽  
Factor Vii ◽  
Factor X ◽  
Anticoagulant Treatment ◽  
Oral Anticoagulant Treatment ◽  
Rate Of Increase ◽  
Long Term Treatment

Protein C (PC) activity and antigen levels have been related to clotting activities of factors VII and X during the induction and withdrawal periods of oral anticoagulant treatment. Both factor VII and PC activities fell rapidly during a gradual induction regime of nicoumalone in six consecutive patients but factor VII showed a more rapid and much more marked depression than PC. In contrast reductions in factor X were much slower. PC antigen although depressed rapidly at the initiation of treatment did not subsequently fall to the same degree as PC activity, The ratio of activity to antigen became progressively smaller.In six further serial patients discontinued from long-term treatment with nicoumalone (mean duration 12-6 months) there was a reversal of the pattern, but with two important differences. Firstly, there was evidence of an excessive rise (“rebound”) of factor VII compared with the steady state levels in these patients; and secondly there was an unexpectedly slow return of PC activity and antigen to normal levels after the oral anticoagulant was withdrawn (levels were still below normal on day 4). Factor X also showed a slow rate of increase, similar to PC activity recovery. These observations lend support to gradual withdrawal of oral anticoagulants after a period of long-term administration. The results suggest that after discontinuation of long-term oral anticoagulants patients may have increased coagulability up to four days.

Mechanized amidolytic technique for determination of factor X and factor-X antigen, and its application to patients being treated with oral anticoagulants.

1980 ◽  
Vol 26 (7) ◽  
pp. 885-890 ◽  
Author(s):  
E M van Wijk ◽  
L H Kahlé ◽  
J W ten Cate
Keyword(s):  
Oral Anticoagulant ◽  
Oral Anticoagulants ◽  
Neutralization Assay ◽  
Factor X ◽  
Extrinsic Pathway ◽  
Oral Anticoagulant Treatment ◽  
Chromogenic Assay ◽  
Russell’S Viper ◽  
The One

Abstract We describe a mechanized chromogenic assay for factor X, the results of which correlate well with those for the one-stage clotting assays for factor X in which it is activated either via the extrinsic pathway by thromboplastin or directly by Russell's viper venom. We purified human factor X and raised monospecific antibodies to it in rabbits. We used our chromogenic assay for factor X to develop a factor-X-inhibitor neutralization assay for determination of factor-X antigen. Patients receiving oral anticoagulant treatment had significantly different factor-X activities after activation via thromboplastin or with Russell's viper venom. The concentration of factor-X antigen, although decreased, significantly exceeded factor-X clotting activity or chromogenic activity in this group of patients. Results of the chromogenic assay for factor X correlated well with results of "Thrombotest," a clotting test introduced by Owren (Lancet ii: 754, 1959) to control anticoagulant therapy. For patients taking oral anticoagulant drugs, the therapeutic range by our assay is 180 to 300 units/L.

COMPARISON OF HUMAN AND RABBIT BRAIN THROMBOPLASTIN IN THE EVALUATION OF LIVER DISEASE

1987 ◽  
Author(s):  
S Kitchen ◽  
R G Malia ◽  
D R Triger ◽  
M Greaves ◽  
F E Preston
Keyword(s):  
Liver Disease ◽  
Prothrombin Time ◽  
Oral Anticoagulants ◽  
Factor Vii ◽  
Rabbit Brain ◽  
Reference Laboratory ◽  
Factor V ◽  
Factor X ◽  
Time Data ◽  
Suitable Alternative

In the UK, rabbit brain thromboplastin has recently replaced human thromboplastin. Since the sensitivity of thromboplastin varies according to species of origin, and the calibration of thromboplastins is based entirely on samples from normal subjects and patients on oral anticoagulants, a separate assessment is required in patients with liver disease. We have compared prothrombin times and specific one stage assays of factors V, VII and X in plasma from 19 patients with establishe < liver disease using rabbit thromboplastin (Manchester reagent, MR) and human thromboplastin (Manchester comparative reagent, MCR). Both materials were kindly provided by the National (UK) Reference Laboratory for Anticoagulant Control. Three separate analyses were performed on the prothrombin time data viz clotting time, prolongation of prothrombin time compared with control and prothrombin ratio. All were significantly longer with MR (p 0.001, paired ‘t’ test) although correlation was goo< (r=0.95 in all instances).In the assay of factors V, VII and X no significant differences were obtained with the two thromboplastins and correlation was good over a range of abnormality (Ranges for MCR and MR respectively were Factor V:0.31-1.23u/ml and 0.32-1.I6u/ml, r=0.96; Factor VII:0.07-1.22u/ml and 0.07-1.17u/ml, r=0.97; Factor X;0.18-1.Olu/ml and 0.17-1.03u/ml, r=0.96. We conclude that in the investigation of the haemostatic defect associated with liver disease rabbit brain thromboplastin is a suitable alternative to human material.

Mechanized amidolytic technique for determination of factor X and factor-X antigen, and its application to patients being treated with oral anticoagulants.

1980 ◽  
Vol 26 (7) ◽  
pp. 885-890
Author(s):  
E M van Wijk ◽  
L H Kahlé ◽  
J W ten Cate
Keyword(s):  
Oral Anticoagulant ◽  
Oral Anticoagulants ◽  
Neutralization Assay ◽  
Factor X ◽  
Extrinsic Pathway ◽  
Oral Anticoagulant Treatment ◽  
Chromogenic Assay ◽  
Russell’S Viper ◽  
The One

Abstract We describe a mechanized chromogenic assay for factor X, the results of which correlate well with those for the one-stage clotting assays for factor X in which it is activated either via the extrinsic pathway by thromboplastin or directly by Russell's viper venom. We purified human factor X and raised monospecific antibodies to it in rabbits. We used our chromogenic assay for factor X to develop a factor-X-inhibitor neutralization assay for determination of factor-X antigen. Patients receiving oral anticoagulant treatment had significantly different factor-X activities after activation via thromboplastin or with Russell's viper venom. The concentration of factor-X antigen, although decreased, significantly exceeded factor-X clotting activity or chromogenic activity in this group of patients. Results of the chromogenic assay for factor X correlated well with results of "Thrombotest," a clotting test introduced by Owren (Lancet ii: 754, 1959) to control anticoagulant therapy. For patients taking oral anticoagulant drugs, the therapeutic range by our assay is 180 to 300 units/L.

A Study of the Effects of the Anti-Rheumatic Drug Ibuprofen (Brufen®) on Patients Being Treated with the Oral Anti-Coagulant Phenprocoumon (Marcoumar®)

1974 ◽  
Vol 2 (4) ◽  
pp. 276-278 ◽  
Author(s):  
D Thilo ◽  
D Nyman ◽  
F Duckert
Keyword(s):  
Serum Concentration ◽  
Bleeding Time ◽  
Anticoagulation Therapy ◽  
Factor Vii ◽  
Fixed Dose ◽  
Factor X ◽  
Oral Anticoagulation Therapy ◽  
Factor Ii ◽  
Rheumatic Drug

The effects of ibuprofen on various parameters relating to blood coagulation were studied in nineteen patients adequately anti-coagulated on a fixed dose of phenprocoumon. The patients were studied for a five-week period and they received a fixed dose of phenprocoumon throughout the whole five weeks. Ibuprofen, 200 mg three times daily was added during weeks three and four. The following tests were performed at weekly intervals; Prothrombin time (Quick), Factor II, Factor VII, Factor X, Ivy bleeding time and serum concentration of phenprocoumon. The results showed that in the dosage given, ibuprofen had no significant effect on any of the above tests. It is suggested that the administration of the anti-rheumatic drug, ibuprofen is safe during long-term oral anticoagulation therapy with phenprocoumon.

Biological Properties of the Thromboplastins and Plasmas Included in the ICTH/ICSH Collaborative Study on Prothrombin Time Standardization

1979 ◽  
Vol 42 (04) ◽  
pp. 1115-1127 ◽  
Author(s):  
E A Loeliger ◽  
L P van Halem-Visser
Keyword(s):  
Prothrombin Time ◽  
Collaborative Study ◽  
Biological Properties ◽  
Bovine Brain ◽  
Factor Vii ◽  
Factor X ◽  
One Stage ◽  
Activation Products ◽  
Position Sensitivity ◽  
The One

SummaryThe fourteen types of thromboplastin included in the ICTH/ICSH Collaborative Study on Prothrombin Time Standardization were investigated with respect to their sensitivity for factor VII, activation products, and PIVKAs. All of these thromboplastins displayed sufficient factor VII sensitivity, and all were sensitive to activation products. After correction for the overall sensitivity slope, rabbit plain thromboplastins were the most sensitive preparations and human as well as rabbit diluted the least sensitive; bovine brain thromboplastin lost its exceptional position. Sensitivity to activation products explains why factors II, VII, and X present in artificially prepared abnormal plasmas may be difficult to assess accurately. Also, all thromboplastins appear to be sensitive for both PIVKA VII and PIVKA X. PIVKA VII acts as a procoagulant which increases the amount of factor VII measured by the one-stage assay technique. PIVKA X inhibits and thus reduces the activity of factor X. The procoagulant activity of PIVKA VII is particulary pronounced for the two lung-brain rabbit thromboplastins (Lyoplastin and Simplastin), whereas the anticoagulant action of PIVKA X is strongest with bovine brain thromboplastin (Thrombotest). Considered as a group, rabbit thromboplastins appear to be less sensitive for PIVKA X and more sensitive for PIVKA VII.As judged from thromboplastin calibration results, all three types of lyophilized reference plasmas are to some degree distinguishable from fresh patient plasmas. Primary calibration of a thromboplastin must therefore still be performed with freshly prepared normal as well as patient plasmas.

ACUTE INTERRUPTION OF ORAL ANTICOAGULANT THERAPY: A THROMBOTIC RISK?

1987 ◽  
Author(s):  
J Rouvier ◽  
H Vidal ◽  
J Gallino ◽  
M Boccia ◽  
A Scazziota ◽  
...  
Keyword(s):  
Anticoagulant Therapy ◽  
Vitamin K ◽  
Oral Anticoagulant ◽  
Protein C ◽  
Oral Anticoagulant Therapy ◽  
Factor Vii ◽  
Factor X ◽  
Functional Protein ◽  
Thrombotic Risk ◽  
Factor Ii

It is still on discussion how oral anticoagulant therapy must be interrupted. A progressive diminution of drug intake have been proposed in order to avoid a MreboundM of vitamin K-dependent procoagulant factors. At the present, it is well known that coumarin drugs affect not only the biologic activity of factors II, VII, IX and X but also Protein C (PC), an inhibitor of coagulation kinetics, and their cofactor Protein S. With the aim to determine the recovery level of PC in relation with the others vitamin K-dependent factors, the effect of suppression of anticoagulant therapy in patients under chronic treatment with acenocoumarin was studied.Quick time, functional factors II, VII, X (one stage methods), functional PC (Francis method) and immunological Factor II and Protein C (Laurell) were determined before and 36 hours after suspension of acenocoumarin administration.Results showed that: 1) Recovery levels of functional Protein C (increased from 28.55% ±2.57 to 72.64% ±5.9) were significantly higer than functional Factor II (22.09% ±2.34 to 30.73% ±8.64), Factor VII (22.55% ±2.01 to 40.73% ±4.85) and Factor X (23.27% ±2.66 to 39.18% ±3.19). Statistical analysis (Newmann-Keuls test) showed at least a p<0.01 between PC increase and factors II, VII or X increment.2) No significant differences were seen between immunological levels of Factor II before and after suspension of acenocoumarin.3) Levels of immunological PC in patients under anticoagulant therapy were higer than functional PC. After acenocoumarin suppression, not correlation was seen between immunological and functional Protein C recovery.It is concluded that acute suppression of acenocoumarin does not induce a thrombotic tendency because the recuperation of functional Protein C is more important than factors II, VII and X recovery.

Evaluation of CoaguChek® XS for Measuring Prothrombin Time in Patients Receiving Long-term Oral Anticoagulant Therapy

2007 ◽  
Vol 27 (3) ◽  
pp. 177-181 ◽  
Author(s):  
Jae Hyeon Lee ◽  
Kyoung Suk Lee ◽  
Dal Sik Kim ◽  
Hye Soo Lee ◽  
Sam Im Choi ◽  
...  
Keyword(s):  
Prothrombin Time ◽  
Anticoagulant Therapy ◽  
Oral Anticoagulant ◽  
Oral Anticoagulant Therapy

Automated Control of Coumarin Therapy by Chromogenic Factor X Assay

1979 ◽  
Author(s):  
R. S. Mibashan ◽  
M.F. Scully ◽  
A.J. Birch ◽  
J.K. Thumpston ◽  
I.R. MacGregor ◽  
...  
Keyword(s):  
Regression Analysis ◽  
Prothrombin Time ◽  
Chromogenic Substrate ◽  
Plasma Samples ◽  
Factor X ◽  
Information Sheet ◽  
Automated Control ◽  
Normal Plasma ◽  
Plasma Factor

A fully automated chromogenic substrate method for measuring plasma factor X has been used to monitor patients attending an anticoagulant clinic. Thirty six patients already established on coumarin therapy were studied by taking four citrate plasma samples from each at monthly intervals. Factor X was assayed in 10 μl aliquots by an adaptation of the method of Aurell & Friberger (Kabi Diagnostica Information Sheet) in an LKB Mark II Analyser with pre-injection facility, allowing 60 s pre-incubation with RW before addition of the substrate S2222. Activity was measured as Δ OD 405/min. Calibration curves were prepared by dilution of lyophilyzed normal plasma, and six coumarin controls were interspersed, with values of 18% (1.09 SD) & 22.2%(1.50 SD) of normal. The F X levels in the 36 patients at each of the monthly clinics were 23.6%. (5.l SD), 23.1 (4.9), 23.1 (5.0) & 23.7% (4.8) of normal, corresponding to RVV/phospholipid coagulant assays of 22.3% (6.3 SD), 22.3 (6.3), 20.7 (5.8) & 21% (6.1) of normal respectively. The prothrombin activities ac each visit, expressed as prothrombin time ratios (PTR), averaged 2.64, 2.80, 2.64 & 2.56. Regression analysis of chromogenic F X values on individual PTR’s gave r=0.65, which led to no change in coumarin dosage when this was repeated blind. The results suggest that rapid, automated F X assays may be suitable clinically, technically & geographically in long-term coumarin control when apparatus & reagents become competitive with established coagulant procedures.

Studies On PIVKA-VII

1981 ◽  
Author(s):  
G Mariani ◽  
G Avvisati ◽  
D Romoli ◽  
M G Mazzucconi ◽  
F Mandelli
Keyword(s):  
Vitamin K ◽  
Therapeutic Range ◽  
Sharp Increase ◽  
Oral Anticoagulants ◽  
Barium Chloride ◽  
Term Treatment ◽  
Factor Vii ◽  
Long Term Treatment ◽  
Two Parameters

The factor VII related antigen (Pivka-VII) in 25 random patients under long term treatment with oral anticoagulants was studied. All the patients had Thrombotest levels well within the therapeutic range (3 to 11%) and had been receiving the drugs for at least 4 months. Factor VII activity (VII: C) mean levels were 8.7 u/dl(sem 0.78) and factor VII antigen (VII: Ag) mean levels were 30.7 u/dl(sem 1.99), (ratio Pivka/Activity 4.04). Barium chloride adsorbed the same mean amount of factor VII: C and factor VII: Ag (8.7 u/dl and 8.0 u/dl respectively). After exposure to cold in 4/25 subjects the “cold activation” phenomenon became evident, characterised by an increase of factor VII: C levels and immodified VII : Ag levels. In the remaining 21 patients, mean VII : C as well as VII: Ag levels did not show modifications (8.5 u/dl and 30.7 u/dl respectively). Moreover, three normal volunteers received three different oral anticoagulants ( Acenocoumarin, Coumarin and Ethyl-Biscomacetate). A sharp increase of factor VII:C levels was observed in all the three subjects (from 30 to 50%), a few hours after the beginning of the treatments, followed by consensual decrease of the two properties related to factor VII that reached the nadir after 48 hours. The vitamin K administration was followed by a rapid and consenual increase of the two parameters.

Sign in / Sign up

Export Citation Format

Share Document