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PubMed1985

An intracellular pool of the procoagulant thromboplastin in human monocytes.

Human monocytes cell extracts have been analysed by density gradient centrifugation in Percoll gradients. Two peaks of activity of the plasma membrane marker enzyme 5' nucleotidase were detected. The main peak was at a density of 1.040 and a secondary one at a lower density. Thromboplastin activity was recovered associated with the main peak of 5' nucleotidase activity in control cells. In NH4Cl treated cells, thromboplastin activity is found at both densities. In agreement with this, labelling of the cell surface with 125I shows a reduction in availability of proteins for labelling between control and NH4Cl treatment. The availability of thromboplastin in monocytes for attack by exogenous trypsin or for initiation of coagulation is also reduced by cultivation with amines. We suggest that the low density peak of 5'nucleotidase and thromboplastin represents an intracellular compartment.

5'-Nucleotidase↗
PubMed1986

Thrombomodulin activity in commercial thromboplastin preparations.

Recently, it was reported that endothelial cells contain a membrane protein which serves as a cofactor for the activation of protein C by thrombin (thrombomodulin). Because many commercial thromboplastins are prepared from vessel-rich tissues/organs (lung, brain, placenta), it was hypothesized that some preparations may contain significant amounts of thrombomodulin; theoretically, thrombomodulin contaminations may enhance the prothrombin time. Among 8 different commercial thromboplastins tested two thromboplastins were found to contain significant amounts of thrombomodulin activity: Simplastin (64 U/ml) and Ortho (12.8 U/ml). However, we were unable to demonstrate that the presence of the thrombomodulin activity in these thromboplastins could affect the prothrombin time either by delaying fibrin formation (formation of thrombin-thrombomodulin complexes) or by inhibiting activated factor V (formation of activated protein C).

Fibrinogen↗
PubMed1992

The inhibition of thromboplastin by apolipoprotein-B and the effect of various associated lipids.

Human apolipoprotein B was purified by barium sulphate adsorption, subsequent delipidation and gel filtration. The protein was then reconstituted in soya bean lecithin and its inhibitory effect towards thromboplastin was assayed by incubation with rabbit brain thromboplastin. The use of an antibody against human apolipoprotein B diminished this inhibition. The level of inhibition of thromboplastin by the reconstituted apolipoprotein was found to be dependent on the concentration of the phospholipids with which it was reconstituted, reaching a maximum inhibition at a lipid: protein ratio of 1:1 (w/w). However, higher phospholipid concentrations or inclusion of cholesterol esters or triglycerides diminished and at certain concentrations reversed the inhibitory effect of the apolipoprotein. These results point towards apolipoprotein B as an inhibitor whose activity towards thromboplastin could be dependent on the complexes it forms with the surrounding lipids.

Animals↗
PubMed1990

Thromboplastin activity of blood monocytes after total hip replacement.

Thromboplastin activity of monocytes from blood of seven patients with total hip replacement was investigated. At 24 h and 48 h after surgery, thromboplastin activity was significantly increased compared to the activity before surgery. Thromboplastin activity of endotoxin-stimulated monocytes was significantly increased at 24 h after surgery. There were no significant changes in Factor V after surgery, Factor VII was significantly lowered at 24 h after surgery, while Factor VIII and fibrinogen were significantly increased at 72 h after surgery. The results indicate that monocyte thromboplastin may be a thrombogenic factor after total hip replacement surgery.

Aged↗
PubMed1951

Fractionation of plasma globulin for prothrombin, thrombokinase, and accessory thromboplastin.

1. Crude globulin from more than 1,000 liters of citrated bovine plasma has been used in developing a procedure for moderately large scale separation of clotting factors. Fraction A, prothrombin, kinase, and thrombin fractions were prepared. Fraction A contained both kinase and accessory thromboplastin, the latter predominating when fraction A was diluted. 2. When prothrombin was activated by kinase, the rate of thrombin production was enhanced by the addition of platelets, or brain lipid, or dilute fraction A. These accessory thromboplastins caused this acceleration only when calcium chloride was added. Even with calcium, they were not effective unless kinase was present. 3. In contrast, the action of kinase was not entirely dependent on either ionic calcium or accessory thromboplastin. The concentrated kinase fraction activated prothrombin in the presence of excess oxalate. Although kinase often contaminates highly purified thrombins, it is probably distinct from thrombin. The ratio of kinase to thrombin was 100 times as great in the kinase fraction as in the thrombin fraction. 4. The kinase fraction, diluted 45,000-fold, to protein-nitrogen concentrations as low as 0.02 microgram per ml., accelerated the conversion of crude prokinase in three-stage tests. 5. The findings are consistent with the following concept of the basic enzymatic mechanism: See PDF for Structure It is now added that calcium and accessory thromboplastin exert their effects by impinging on the basic mechanism, in a chemically secondary or indirect manner.

Animals↗
PubMed1979

Whole-blood clotting time, activated partial thromboplastin time, and whole-blood recalcification time as heparin monitoring tests.

The authors performed whole-blood clotting time (WBCT), activated partial thromboplastin time (APTT), and whole-blood recalcification time (WBRCT) tests on normal blood or citrated plasma, each milliliter containing 0-0.5 unit heparin, and on samples from patients, of whom many were receiving heparin anticoagulation therapy. Six partial thromboplastin reagents were used. Linearity between clotting time and heparin concentration was observed with WBCT and APTT, determined with Hyland partial thromboplastin (kaolin-activated) and Dade ("Improved" Activated Cephaloplastin and Actin) reagents. With a General Diagnostics preparation (Platelin -plus, celite as the activator) and another Hyland partial thromboplastin reagent (silica-activated), the sensitivity to heparin decreased to beyond 0.3 unit/ml plasma. No correlation was observed with the old Dade Activated Cephaloplastin reagent, WBRCT was completely insensitive to heparin in concentrations as high as 0.24 unit/ml blood. With patient samples, correlations were observed between WBCT and Hyland (kaolin) APTT, and between Hyland and Dade Actin APTT. However, WBCT and WBRCT, and APTT and WBRCT, correlated poorly.

Blood Coagulation Tests↗
PubMed1982

Synthesis of thromboplastin by U-937 cells.

A human monocytoid cell line (U-937) produces a procoagulant identified as thromboplastin when stimulated with phytohaemagglutinin (PHA), endotoxin, immune complexes, the phorbol ester 12-O-tetradecanoyl-phorbol 13-acetate (TPA) or the divalent ionophore A 23187. The basal thromboplastin expression of these cells and the increased activity induced by the stimulants were dependent on supply of fresh medium suggesting that the synthetic rate was highest when the cells were in logarithmic growth. Inducible thromboplastin synthesis was inhibited by actinomycin D or cycloheximide, indicating dependence on messenger RNA and protein synthesis. Differentiation of the cells in the macrophage direction by TPA did not make the cells more responsive to PHA. Thromboplastin induction in U-937 cells was potentiated by the presence of lymphocytes, especially when stimulated with PHA or endotoxin. This supporting effect was also obtained by conditioned medium from lymphocyte cultures, suggesting a role for a soluble lymphocyte product.

Antigen-Antibody Complex↗
PubMed1985

Increased sensitivity to thromboplastin synthesis in blood monocytes from pre-eclamptic patients.

The thromboplastin activity in blood monocytes was investigated in third-trimester pregnancies comprising 11 patients with severe pre-eclampsia, 10 with essential hypertension and 18 normal pregnancies. Thromboplastin activity in unstimulated monocytes from the severe pre-eclamptic group was on average three times that found in the normal pregnant group, but variation was wide and the differences were not statistically significant. Thromboplastin activity in endotoxin-stimulated monocytes was significantly higher in the severe pre-eclamptic group than in the other two groups (normal and chronic hypertensive). In the severe pre-eclamptic group, there was a significant negative linear correlation between thromboplastin activity of the endotoxin-stimulated monocytes and factor VII. Fibrinogen, factor VII and alpha 2-antiplasmin were significantly lower in the severe pre-eclamptic group than in the normal pregnant group, whereas no differences were observed in factors V, VIII, AT-III and prekallikrein.

Adult↗
PubMedDate not supplied

Comparison of a recombinant thromboplastin with Thrombotest for oral anticoagulant control.

Thrombotest results expressed in international normalized ratio (INR) values, obtained in 108 patients on oral anticoagulant treatment, were compared with prothrombin time (PT) results with a recombinant thromboplastin. The former results were obtained on an Amelung coagulometer, the latter on a photo-optical instrument. Using the Thrombotest method, performed within 2 h after sampling as the reference method, a first group of 63 patients had an INR value between 2 and 4. This group was considered as adequately anticoagulated and served as a true positive population in further analysis. The remaining 45 patients (true-negative group) had an INR value below 2 or higher than 4 and could thus be considered as inadequately anticoagulated. Using these definitions, a sensitivity of 86% and a specificity of 96% could be calculated for the PT with the recombinant thromboplastin. All tests from patients on oral anticoagulant treatment were also performed after 24 h storage of the blood or plasma samples at room temperature. When we compared the reference Thrombotest results with those of the late Thrombotest and the late PT recombinant thromboplastin, sensitivities of 86 and 86% as well as specificities of 91 and 96% were found, respectively. In conclusion, PT with a recombinant thromboplastin on a photo-optical instrument, even after prolonged storage of the plasma samples at room temperature, can be considered as suitable for oral anticoagulation control.

Administration, Oral↗
PubMed1980

Comparison of thromboplastins used for oral anticoagulant control.

Prothrombin ratio (PR) ranges of 1.5-2.5 based on clinical effect are used for oral anticoagulant control with most commercially available thromboplastins, whereas with Australasian Reference Thromboplastin (ART) 2.0-3.5 is recommended. Plasmas from patients taking oral anticoagulants were concurrently tested with various thromboplastins and interrelationships between these products were determined. Although PR's with ART appear higher, in fact therapy based on ART guidelines is considerably more conservative than that monitored with most commercial thromboplastins.

Administration, Oral↗
PubMed1999

Recombinant and tissue extract thromboplastins for determination of international normalised ratio in over-anticoagulated patients.

The international normalised ratio (INR)/international sensitivity index (ISI) system is established for calibration of thromboplastins for laboratory monitoring of oral anticoagulant therapy. The calibration procedure employs patients stabilised on oral anticoagulants, and is therefore validated for patients within the therapeutic range. For practical reasons, the system is used for patients at all levels of therapy, including over-anticoagulated patients with particularly low levels of factors II, VII and X. We studied patients within and above the therapeutic range, using a thromboplastin containing recombinant human tissue factor (Innovin) and two tissue extract thromboplastins. In samples with INRs from 2.0 to 4.0, there was good agreement between results obtained with the three systems (mean INRs within 4% of each other). In patients with INRs > 4.0, results with a human placental extract reagent (Thromborel S) were similar to those obtained with a rabbit brain thromboplastin (IL PT Fib Hs Plus); mean INRs were 6.30 and 6.32 respectively (not significant). Results with Innovin (mean INR: 7.67) were significantly (P < 0.001) greater (on average by 22%) than those obtained with the other two materials. The discrepancy between results with different reagents negatively correlated with factor VII levels. Thus, the lower the factor VII level, the greater was the discrepancy between INRs. Unexpectedly, there was a positive correlation between factor V level and the difference between INRs with different reagents. Thus, the higher the factor V level, the greater was the discrepancy between INRs. The effect of these differences at higher INRs on patient management is unknown, but the recently revised UK guidelines recommend that management of these patients should be influenced by clinical factors, reducing the relative importance of discrepancies between results obtained with different systems.

Anticoagulants↗
PubMed2000

[The quality indices of the Quick method using thromboplastin reagents performed manually and instrumentally].

The reproduction and results of Quick's method with tissue thromboplastin (Kirov Institute of Hematology and Blood Transfusion--KIHBT) and Excel and Excel S simplastins (Organon Teknika, Netherlands) in the tube and automated versions were compared. Semiautomated coagulometer COAG-A-MATE XM and automated COAG-A-MATE RA-4 of the same firm were used. Three Verifi plasmas (Organon Teknika) with different activities of factors II, VII, IX, and X were used. Tests with thromboplastin manufactured by KIHBT were well reproduced both in the tube and automated modifications (CV < 10%). This thromboplastin can be used for monitoring the efficiency of therapy by indirect anticoagulants. For evaluating the correlation between results, plasma samples from 21 donors and 12 patients treated by indirect anticoagulants with the prothrombin index (PI) lower than 75% were analyzed. The PI of the tube and automated modifications were in good correlation. Tests with the Russian thromboplastin showed high coefficients of correlation between the two modifications of Quick's test, which recommends the use of these device-reagent combinations for evaluation of PI.

Blood Coagulation Tests↗
PubMed2001

[Study of thromboplastin sensitivity].

Comparative analysis of foreign and Russian thromboplastins demonstrated differences in the notions "activity" and "sensitivity" and the significance of low value of International Index of Sensitivity (IIS). Sensitivity of thromboplastin manufactured by RENAM Firm, Russia (IIS = 1.5) to deficiency of prothrombin factors II, VII, X has been demonstrated, which means that this thromboplastin can be used for diagnosis of deficiency of each of these factors. The authors consider that testing of thromboplastin sensitivity to factor VII is the main criterion of its fitness for monitoring anticoagulant therapy.

Animals↗
PubMed2002

[Use of domestic thromboplastins with attested international indices of sensitivity in the treatment of thrombophilia].

Clinical evaluation of thromboplastins manufactured by RENAM (Moscow) with international index of sensitivity (IIS) 1.1-1.5 and comparison of the results with the data obtained in the same patients with foreign thromboplastins (Dade, USA; Behring, Germany; Diamed, Switzerland) and Mediolab thromboplastins (Russia) manufactured from different raw materials (rabbit brain and human placenta) showed that by sensitivity to indirect anticoagulants, Russian thromboplastins made by RENAM and Mediolab firms are not inferior to the best foreign analogs.

Administration, Oral↗
PubMed2002

Discrepant sensitivity of thromboplastin reagents to clotting factor levels explored by the prothrombin time in patients on stable oral anticoagulant treatment: impact on the international normalized ratio system.

BACKGROUND AND OBJECTIVES: We tested the principle of local International Normalized Ratio (INR) calibration using INR calibrator plasmas (PT Calibration Plasma Kit, Behring), two thomboplastin reagents (Neoplastin plus, rabbit brain, Stago, and Recombiplastin, recombinant human tissue factor, Ortho Diagnostics) and the same coagulometer (STA, Stago) on 92 patients on stable oral anticoagulant treatment. DESIGN AND METHODS: A four-point calibration was obtained with each reagent by linear regression (sec/INR) on a log-log scale (r > or = 0.999). The bias between the two reagents (Recombiplastin - Neoplastin Plus) was reduced from 31.7% to 17.5% and 7.5% (p=0.001) when results were expressed, respectively, as PT ratio (using the mean normal prothrombin time as denominator term), INR (using instrument-specific ISI supplied by the manufacturers) and calibrated INR, but there was a consistently significant regression of the differences over the average values even after log transformation (r > or = 0.586). The bias between the reagents was reduced to 1% (p=ns) when assuming Recombiplastin as the reference thromboplastin and applying Tomenson's correction, but limits of agreements were as large as 20%. Factor VII, X, V and II activity was measured with the two thromboplastin reagents in all plasma samples using immunodepleted plasmas (Stago). RESULTS: Statistically significant biases were observed for all clotting factors with the two reagents (Recombiplastin Neoplastin Plus) and ranged from 3.5 % (FII) to 37.2% (FVII). In addition, for FVII and FV there was a significant regression of the difference over the average value (after log-transformation, r > or = 0.282). The patients were divided into 3 groups according to their degree of anticoagulation (INR <2.0; INR between 2.0 and 3.5; INR >3.5). Factor levels differed significantly with the two reagents throughout the 3 groups of patients. In addition, the relative distributions of the 3 vitamin K-dependent factors also differed in the 3 groups with the two thromboplastin reagents. INTERPRETATION AND CONCLUSIONS: The discrepant sensitivity to factor VII, X and V levels of the two thromboplastin reagents explored in this study prevents INR calibration with commercially available calibrator plasmas and is responsible for a significant variability in INR values even under optimal conditions of INR calibration.

Adult↗
PubMed2002

A comparison of INRs after local calibration of thromboplastin international sensitivity indexes.

UNLABELLED: There are approximately 300 reagent/instrument combinations for performing prothrombin times/international normalized ratios (PT/INR) in the United States. Manufacturers and laboratories continually struggle to ensure that the International Sensitivity Index (ISI) of their thromboplastin is accurate for assaying PT/INR. OBJECTIVE: This study reports the feasibility of a new method to locally calibrate ISI of thromboplastin using the mechanical STA automated coagulation analyzer (Diagnostica-Stago Inc.) and two photo-optic coagulation analyzers, the BCS (Dade-Behring) and CA-540 (Sysmex). DESIGN: Neoplastine CI+ (CI+) (Diagnostica-Stago Inc); Thromboplastin C+ (TC+); Thromborel S (TRS); and Innovin (I) (Dade-Behring) were used in this study. A mean normal PT (MNPT) was determined for each reagent/instrument combination using samples from 25 normal individuals. Manufacturer instrument specific ISI values were not available for the STA with TC+, TRS and I. The CA540 had no ISI value for CI+ and the BCS system had no manufacturer assigned ISI values for TC+ and I; generic photo-optic and mechanical ISI manufacturer values were used for these two systems. Local on-site calibration was performed using frozen plasma calibrators to determine ISI values for each thromboplastin. Post-calibration, 95 patient samples were assayed for each reagent/instrument system combination using the manufacturer ISI and the local calibrated ISI to determine the INR result. PATIENTS: Patients from whom samples were obtained included five with a lupus anticoagulant, 30 on heparin therapy, and 60 on coumadin therapy. RESULTS: Differences between manufacturer versus local calibrated ISI ranged from 0.9% to 18.9% for normal sample INRs and from 0.8% to 16.4% for patient sample INRs. The number (or proportion) of patient specimens with clinically significantly different INR values (>10.0% difference) ranged from zero for several reagent combinations to more than half (or >50.0%) of those tested for several other combinations. CONCLUSION: Our results indicated that by locally calibrating ISI values, each laboratory may eliminate variability and guesswork between different reagent/instrument systems for ISI values when performing PT/INR assays and potentially improve the clinical accuracy of their patients' PT/INR results.

Automation↗
PubMed1992

[Interaction of human thrombin I fragment, prethrombin I, and alpha-thrombin with tissue thromboplastin].

The binding of 125I-labeled prothrombin fragment I. prethrombin I and alpha-thrombin to native and papain-treated tissue thromboplastin in the presence of CaCl2 of EDTA was studied. The experimental curves plotted in the Scatchard coordinates testify to the presence in thromboplastin of two types of fragment I binding sites: those with a high (Kd = 7.6 x 10(-6) M) and moderate (Kd = 1.3 x 10(-8) M) binding affinity. The parameters of fragment I binding and their changes reproduced, for the most part, the mode of prothrombin binding observed in previous studies. The experimental results provide indirect evidence in favour of a hydrophobic role of Ca(2+)-dependent binding of prothrombin fragment I to thromboplastin. The binding of prethrombin I was nonspecific and Ca(2+)-independent, whereas alpha-thrombin showed a relatively high level of nonspecific electrostatic binding which was competitively inhibited by Ca2+. Thromboplastin proteins interacted (both directly and in a Ca(2+)-independent fashion) with all the prothrombin derivatives under study.

Binding Sites↗
PubMedDate not supplied

The role of arachidonic acid release and lipoxygenase pathway in lipopolysaccharide-induced thromboplastin activity in monocytes.

Lipopolysaccharide (LPS) stimulation of human monocytes in heparinized whole blood in vitro as expressed by induced activity of thromboplastin, has been studied. An essential role of arachidonic acid (20:4) release was found. 2,4'-Dibromoacetophenone, a phospholipase A2 inhibitor, totally blocked the induced synthesis of thromboplastin activity. Furthermore, nordihydroguaiaretic acid (NDGA), a lipoxygenase inhibitor, had an effect on the LPS-induced thromboplastin synthesis which varied from no inhibition in individuals insensitive to LPS ('low responders'), up to 80% inhibition in the person with the highest response ('high responder') to LPS. Platelets were found to be partially responsible for this difference. Thus, monocytes from high responders cross-combined with platelets from low responders were much less prone to LPS stimulation than they were in the presence of high responder platelets. Intake of acetylsalicylic acid caused a 50% increment of LPS-induced thromboplastin synthesis, and this effect was mediated by platelets.

Acetophenones↗