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PubMed1978

The influence of residual factor VII on the sensitivity of brain thromboplastin.

One-stage prothrombin times of normal and of factor VII-deficient beagle plasma were determined with two types of beagle brain thromboplastin, one prepared from normal beagles and the other from factor VII-deficient beagles. There was little difference between the reagents in the prothrombin times obtained for normal plasma. However, when factor VII-deficient plasma was tested, reagent prepared from factor VII-deficient beagles gave considerably longer prothrombin times than were obtained with the normal reagent and the difference increased with increasing reagent concentration to a maximum at 140 mg/ml. Prothrombin times of a series of mixtures of normal and factor VII-deficient plasma indicated that the presence of only 1/90 part of normal plasma was necessary to compensate for the difference between the two reagents. Determination of the iron content of the reagent suggested that the microcirculation of an average brain contained some 1.8 g of whole blood. The finding that brain thromboplastin prepared from factor VII-deficient beagles is more sensitive to a deficiency of factor VII in plasma, presumably a result of the smaller quantity of factor VII present in the reagent, is compatible with the known kinetics of extrinsic coagulation.

Animals↗
PubMed1982

Activated partial thromboplastin time and activated coagulation time in monitoring heparinized cats.

Cats were given heparin (IV or subcutaneously) at various dosages to determine the optimal dosage, route, and schedule for therapeutic anticoagulation. The activated coagulation time and activated partial thromboplastin time tests were used to evaluate heparin concentration. A dosage of 100 U/kg given IV produced an anticoagulation that was too brief and more potent than was desirable. Subcutaneous dosages of 250 and 375 U/kg produced therapeutically acceptable anticoagulation for 8 hours, whereas dosages of 500 and 1,000 U/kg causes an anticoagulation that was longer and more potent than was desirable. The activated coagulation time correlated well with the activated partial thromboplastin time in determining the degree of heparinization with certain limitations.

Animals↗
PubMed1981

[Sensitivity of several commercial thromboplastins to non-carboxylated clotting factors II and X (author's transl)].

All reagents for determination of thromboplastin time (Quick-test) tested so far are sensitive to non-carboxylated clotting factor X, and sensitivity varies, depending on the reagent. The thromboplastins of Behring and Thrombotest are very sensitive. The preparations of La-Roche and Boehringer are somewhat more sensitive than those of Dade and Goedecke. Only the differences between the first group (Behring, Thrombotest) and the others are significant. There is a good correlation between factor X sensitivity, prothrombin time and non-carboxylated clotting factor X sensitivity, with all reagents. These results may be of significance for quality control and standardization of the prothrombin time.

Biomarkers↗
PubMedDate not supplied

[Penetration of the heparin-thromboplastin complex into brain tissues after administration of the complex into healthy animals and into animals with the prethrombotic state caused by atherogenic diet].

The possibility of heparin penetration into brain cells was shown. The penetration occurred apparently in the form of heparin complexes with thromboplastin. The intensity of penetration depended on the functional state of the anticoagulation system. Accumulation of 35S-heparin and of its complex with thromboplastin was distinctly limited in brain tissue of animals with depression of the anticoagulation system followed the long-term maintaining of the animals on an atherogenic diet.

Animals↗
PubMed1981

Prothrombin-activator (thromboplastin) generation in the blood of water snake (Natrix piscator).

The generation of prothrombin-activator (thromboplastin) in water snake (Natrix piscator) is clearly delayed, compared to a mammalian system, but the final activity is well comparable to that in man, when homologous sources of "phospholipid" (erythrocyte-lysate) and of substrate plasma are employed in one stage "thromboplastin generation test". The use of heterologous source of either of the above reagents resulted in significantly longer clotting times; hence the need for homologous source of above reagents in the test is emphasized for comparative studies on animal haemostasis.

Animals↗
PubMed1980

[Antithrombin III level on the intravenous injection of tissue thromboplastin and heparin to rats with depressed blood anticoagulating system function due to an atherogenic diet].

Rats with depressed function of the blood anticoagulation system due to an atherogenic diet had a slightly reduced level of antithrombin III by the sixth month of the diet as compared to the indices of control animals. Intravenous injection of tissue thromboplastin revealed delayed and incomplete binding of thrombin by antithrombin III in the experimental animals, which was characterized by only an insignificant decrease in the level of the inhibitor as compared to its change in control animals kept under similar experimental conditions. Preliminary intravenous injection of small doses of heparin into animals with depressed function of the anticoagulation system and low level of heparin in blood stimulates and promotes the binding of thrombin by antithrombin III under conditions of increased thrombinogenesis following intravenous injection of tissue thromboplastin.

Animals↗
PubMedDate not supplied

[Comparative study of the duration of action of heparin--thromboplastin complex in the bodies of animals maintained on natural and atherogenic diets].

Within 10 min after single intravenous administration of the heparin-thromboplastin complex into animals, kept on natural and atherogenic diets, the total fibrinolytic activity and the non-enzymatic fibrinolysis were increased in blood plasma, which maintained within 60 min after the complex administration. Within 90 min of the experiment the non-enzymatic fibrinolysis was decreased in blood plasma of both groups and the activity reached the initial level within 120 min after the treatment. The increase in the total and non-enzymatic fibrinolysis was distinctly higher in controls as compared with animals kept on atherogenic diet. Within 60 min after administration of the heparin-thromboplastin complex physiological solvents of the unstabilized fibrin were found in liver and lung tissues of control animals as well as in lung and heart tissues of animals kept on the atherogenic diet.

Animals↗
PubMedDate not supplied

[Use of fractionated soy phospholipids in a test of activated partial thromboplastin time].

Fractionated phospholipids (PL) from soya beans were tried as partial thromboplastin (PT) in the activated partial thromboplastin time test. PL fractions were investigated for content of individual phospholipid classes, acidity and procoagulant activity as were PT from human brain and chromatographically pure PL. Procoagulant activity of phospholipid mixtures is higher than that of chromatographically pure PL and is unrelated to PL variety. Soya PL mixtures with human brain PT demonstrating high procoagulant activity are characterized by 0.3-0.8 ratio of total acid to total neutral PL and acid number 40-60 mg KOH. Isolated from soya PL procoagulants accelerate clotting of plasma from healthy subjects 2.2-fold being just a little less active than brain PL. This makes the above procoagulants usable as test-reagent for evaluation of hemostasis.

Chemical Fractionation↗
PubMed1994

Recombinant versus high-sensitivity conventional thromboplastin: a randomized clinical study in patients on oral anticoagulation.

A prospective, randomized, double-blind clinical trial was carried out in a single center to compare the clinical and laboratory quality of oral anticoagulant therapy monitored with recombinant tissue factor (RTF) or with a sensitive, human-derived, conventional thromboplastin (CT) in the PT test. Seven hundred and fifty-seven consecutive patients receiving oral anticoagulation for various indications were randomized to RTF (n = 379) or CT (n = 368) for 6 months. Total follow-up was 167 and 153 patient-years for RTF and TP groups respectively. Fifty-six bleeding events were observed: 31 in the RTF group and 25 in the TP group. The incidence of bleeding was 18.5 and 16.5% pt-yrs for RTF and TP patients respectively (n.s.). The event-free follow-up curves were not significantly different between the two groups. The laboratory quality of oral anticoagulation was evaluated with the "last check in file" method: therapeutic INR was found in the same proportion of RTF and TP patients (70.2% vs 68.8%). Our study shows that RTF is as effective as a sensitive, conventional thromboplastin for monitoring oral anticoagulation.

Administration, Oral↗
PubMed1994

Results of a multicenter study assessing the status of standardization of a recombinant thromboplastin for the control of oral anticoagulant therapy.

An international collaborative study involving 20 laboratories was undertaken to evaluate the status of standardization of a commercial recombinant thromboplastin. The results show that the reagent fulfills the WHO requirements for thromboplastin calibration against two International Reference Preparations (IRP) from different species, because there was a linear relationship of log-transformed prothrombin times as measured by the recombinant reagent and the two IRPs in normal individuals and patients stabilized on oral anticoagulants. The regression lines drawn through the patient data points passed through the normal data points in the majority of instances. The average ISI values for three different batches were close to unity. On the average, the ISI value calculated against BCT/253 (human, plain) was slightly smaller than that against RBT/79 (rabbit, plain). The between laboratory precision of calibration (CV = 5-6%) did not change whether BCT/253 or RBT/79 was used, whereas it was substantially improved when the calibrations of batches 2 and 3 were performed against batch 1, arbitrarily taken as standard (CV < or = 1.7%). Statistical analysis to test for differences between slopes revealed no significant between-batch differences in 16 of 20 laboratories. However slight differences for the third batch (2.8% less than the average ISI value of batches 1 and 2) leave room for further improvement in the standardization of the reagent.

Animals↗
PubMed1994

Thromboplastin related differences in the determination of international normalised ratio: a cause for concern? Steering Committee of the UK National External Quality Assessment Scheme in Blood Coagulation.

When the International Normalised Ratio (INR) is used for control of oral anticoagulant therapy the same result should be obtained irrespective of the laboratory reagent used. However, in the UK National External Quality Assessment Scheme (NEQAS) for Blood Coagulation INRs determined using different reagents have been significantly different. For 18 NEQAS samples Manchester Reagent (MR) was associated with significantly lower INRs than those obtained using Diagen Activated (DA, p = 0.0004) or Instrumentation Laboratory PT-Fib HS (IL, p = 0.0001). Mean INRs for this group were 3.15, 3.61, and 3.65 for MR, DA, and IL respectively. For 61 fresh samples from warfarinised patients with INRs of greater than 3.0 the relationship between thromboplastins in respect of INR was similar to that observed for NEQAS data. Thus INRs obtained with MR were significantly lower than with DA or IL (p < 0.0001). Mean INRs for this group were 4.01, 4.40, and 4.59 for MR, DA, and IL respectively. We conclude that the differences between INRs measured with the thromboplastins studied here are sufficiently great to influence patient management through warfarin dosage schedules, particularly in the upper therapeutic range of INR. There is clearly a need to address the issues responsible for the observed discrepancies.

Animals↗
PubMed1993

Standardizing the prothrombin time. Calibrating coagulation instruments as well as thromboplastin.

Recently, indications for anticoagulation with warfarin have increased, prothrombin time (PT) monitoring at offices and homes has become available, and the international sensitivity index (ISI) has been recognized as a means of adjusting for differences in thromboplastins to standardize warfarin sodium dosing. However, different coagulation instruments may yield differences in PTs even after correcting for the ISI by means of the international normalized ratio (INR) (INR = [PT measured ISI/PT normal]). Because the PTs and INRs from our Anticoagulation Clinic (portable PT monitor, ISI = 2.04, normal PT = 12.0 seconds) differed from the hospital reference laboratory (ISI = 2.01, normal PT = 12.0 seconds) despite nearly identical ISIs and equivalent control or normal PTs, we systematically compared the two systems. During a 3-month period, we studied two groups of 50 consecutive patients who had been receiving a stable dose of warfarin. After a single venipuncture, PTs and INRs were measured independently, and regression lines were calculated. Within each group, the results from the different instruments were not identical, but they were highly correlated. In comparing INRs, the regression lines for the separate and combined groups were as follows: group 1 monitor INR = 0.49 reference INR + 0.81, r = .94; group 2 monitor INR = 0.57 reference INR + 0.86, r = .88; and combined monitor INR = 0.49 reference INR + 0.95, r = .89. Only 82% of the differences for all samples were within 1.0 INR units. We concluded that the instrumentation effect may be clinically meaningful, and coagulation instruments as well as thromboplastins should be calibrated to standardize warfarin therapy.

Blood Coagulation Tests↗
PubMed1977

[Functional deficiency of erythrocyte thromboplastin factor].

A study of human erythrocytes in healthy and sick persons showed changes in the erythrocytes procoagulant activity, namely a reduction of the whole cell thromboplastin activity despite a sufficient procoagulant factor content. A term "functional insufficiency of thromboplastin factor of erythrocytes" or briefly "erythrocytic thrombopathy" is suggested for the above-mentioned changes of erythrocytes, similar with the changes of platelet procoagulant properties in one of the thrombopathy forms.

Adolescent↗
PubMedDate not supplied

The tissue thromboplastin inhibition test in diabetics without cerebro-cardiovascular diseases.

In 45 patients with diabetes mellitus (DM) without cerebro-cardiovascular diseases (CCVD) the modified method of the tissue thromboplastin inhibition test (TTIT) was studied. TTIT is the method of detection of the lupus anticoagulant (LA), LA, first recognized in patients with systemic lupus erythematosus, is presented by a prolonged activated partial thromboplastin time (APTT), a slightly to moderately prolonged prothrombin time (PT), and high incidence of biological false-positive seroreactions for syphilis (BFP). In patients with LA, thrombotic events have been reported. Six of the 45 diabetic patients were TTIT-positive (13.3%). All control subjects were TTIT-negative. In the TTIT-positive diabetics APTT and PT were normal. BFP also were not observed. The difference between LA and these results in TTIT-positive diabetics remains unclear. Clinical profiles except for duration of DM between the TTIT-negative and TTIT-positive diabetics did not differ. Follow-up studies may resolve an association between the results of TTIT and DM.

Adult↗
PubMed1979

Interactions among Hageman factor (HG, Factor XII), plasma thromboplastin antecedent (PTA, Factor XI), plasma prekallikrein (PK, Fletcher factor) and high molecular weight kininogen (HMW-K, Fitzgerald factor) in blood coagulation.

Studies of plasmas from individuals with Hageman trait (factor XII deficiency), plasma thromboplastin antecedent (PTA, factor XI) deficiency, Fletcher trait (plasma prekallikrein deficiency) and Fitzgerald trait (high molecular weight-kininogen deficiency) have revealed the importance of these proteins in blood coagulation. The interactions among them, however, are not fully elucidated. We have studied these reactions by two different approaches. (1) In a purified system, high molecular weight kininogen was absolutely required for activation of PTA by HF and ellagic acid (EA). The yield of activated PTA was proportional to the amount of HF, HMW-K, and PTA in the mixtures, suggesting that these three proteins may form a complex in the presence of EA. (2) In experiments with whole plasma, we took advantage of the adsorption of EA to Sephadex gels. When normal plasma or plasma deficient in HF, PK, HMW-K or PTA was exposed to Sephadex-EA and was separated by centrifugation, each supernatant plasma except that deficient in HF shortened the prolonged partial thromboplastin time (PTT) of HF-deficient plasma. Plasma simultaneously depleted of HMW-K, PK and PTA also shortened the PTT of HF-deficient plasma and of plasma depleted of HF and PK, but had virtually no procoagulant effect upon the PTT of plasma depleted of HF and MHW-K. Thus, exposure of HF in plasma to Sephadex-EA appeared to generate a clot-promoting form of HF in the absence of other clotting factors, but its expression required the presence of HMW-K.

Blood Coagulation↗
PubMed1981

Plasma thromboplastin antecedent (Factor XI) deficiency in a black family.

A black man with a prolonged partial thromboplastin time has a severe deficiency of plasma thromboplastin antecedent (PTA) (factor XI) measured both in clotting assays and immunoassays, suggesting a diagnosis of homozygous PTA deficiency. His offspring seemed to be heterozygous carriers of PTA deficiency. Additionally, the proband and two of his children had decreased Hageman factor (factor XII) levels consistent with those of heterozygous carriers of Hageman trait. To our knowledge, this is the first case known of PTA deficiency in a black person. Its pattern of inheritance was independent of that of factor VII deficiency.

Black People↗
PubMed1998

Falsely elevated INR results due to the sensitivity of a thromboplastin reagent to heparin.

The aim of this study was to determine the effect of heparin therapy on the international normalized ratio (INR). In vitro heparin sensitivity curves were created using normal and warfarinized plasma samples from patients. The INR results were measured with each of two reagents. In addition, a comparison of INR values with these two reagents was performed on plasma from patients receiving therapeutic heparin and warfarin. The INR values were measured before and after heparin removal with a heparin adsorbent system. While one of the reagents was found to be sensitive to even low levels of therapeutic heparin, the other thromboplastin was resistant up to at least 0.9 U/mL. The INR values determined for patients with one of the reagents were found to be erroneously elevated by an average of 16%. The error ranged from 2% to 55% depending on the in vivo heparin concentration. With the other reagent, the INR values were not substantially affected by heparin. Previous studies have described the effect or lack thereof of heparin on the prothrombin time. The present study demonstrates that the degree to which INR results are prolonged by heparin therapy depends on the reagent formulation. As the therapeutic index for monitoring warfarin is relatively narrow (2.0-3.0), an INR value that is falsely elevated due to reagent sensitivity may precipitate premature cessation of heparin therapy and place certain patients at risk for recurrent thrombosis in the short term.

Adsorption↗
PubMed1995

[The resistance of activated partial thromboplastin time to heparin infusion during hemodialysis].

Activated partial thromboplastin time (aPTT) during heparin infusion in 10 patients on regular dialytic treatment was evaluated. At end-dialysis (3 hours) plasma heparinization ranged between 2000-4000 IU and from the clinical point of view dialytic performance was good. At end-dialysis aPTT was 53 +/- 14 seconds: this value is under the prescribed aPTT prolongation (1.5-2 times baseline values) to achieve a therapeutic heparin plasma level. Physiopathological implications of this aPTT "resistance" to heparin infusion are studied.

Adult↗