SEARCH · Search PubMed

Results for “THROMBOPLASTIN”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 235 records · Page 13Linked to original sources

PubMed1971

The "therapeutic range" of the one-stage prothrombin time in the control of anticoagulant therapy: the effect of different thromboplastin preparations.

Commercially available thromboplastin reagents and two human brain preparations have been compared using the one-stage prothrombin time and plasma samples from patients receiving long-term oral anticoagulant therapy. Considerable variation is noted between various thromboplastins using the same plasma sample. The commercially available thromboplastins give shorter prothrombin times than do human brain preparations. With the latter, the "therapeutic range" is represented by a prothrombin time of about 1.8 to 3.0 times the normal control value, whereas with commercial preparations the "therapeutic range" is about 1.25 to 1.75 times normal. The implications of these observations are discussed; the desirability of standardization of the one-stage prothrombin time is emphasized.

Anticoagulants↗

PubMed1979

Results of calibration by the Dutch National Reference Laboratory of the thromboplastins included in the ICTH/ICSH collaborative study of prothrombin time standardization.

Results obtained with the original calibration procedure of Biggs and Denson obtained by one expert laboratory compare well with those obtained from the ICTH/ICSH collaborative study. The simplified calibration procedure described in 1975 should only be used for the assessment of inter-batch variability of a given brand of thromboplastin; for the calibration of unlike thromboplastins, the simplified procedure should be revised by using more than two abnormal plasmas, e.g. different plasmas representing seven levels of anticoagulation between international calibrated ratios (ICRs) from 1.5 to 4.5. The formula for the calculation for the proposed ICRs based on the calibration constant should be modified to allow for instances where the calibration line for dissimilar thromboplastins, fitted in the therapeutic range, does not pass through the origin of ratio 1,1.

Blood Preservation↗

PubMed1977

Localization of tissue thromboplastin in the human brain.

Monospecific antisera against the purified protein component of tissue thromboplastin (apoprotein-III) from human brain have been raised in goats and rabbits. The antisera neutralized tissue thromboplastin prepared from brain, thyroid gland and pulmonary tissue, indicating that apoproteins in the various preparations cross-reacted immunologically and therefore were similar or identical. Comparison of the activities of tissue thromboplastin preparations from 34 different areas of the brain demonstrated a characteristic distribution pattern and a wide range of activities. White and grey matter from the same areas had similar activities. Bulbus and tractus olfactorius, medulla oblongata, corpus pineale, hippocampus and hypothalamus contained 160-270% of the average activity, whereas cerebellum globus pallidus, nucleus ruber and substantia nigra contained 30-60%. The distinct distribution pattern was unrelated to tissue vascularization, and may suggest that apoprotein-III could serve other functions, apart from the coagulation of blood. The predominance in phylogenetically older brain regions would suggest that it represents a primitive or fundamental feature.

Animals↗

PubMed1977

Determination of coagulation factors (II-VII-X) and kaolin partial thromboplastin time by the LKB 8600 Reaction Rate Analyser.

Testing of a modified Reaction Rate Analyser 8600 in the automatic determination of coagulation time was accomplished with the assays Thrombotest Normotest and Kaolin Partial Thromboplastin Time. Variations in extinctions, from the adding of start reagent until coagulation, were recorded. The coagulation activities, found by the automatic method for the assays Thrombotest and Normotest, were compared with a manual method. Thrombotest showed a good correlation: 0.30 greater than P greater than 0.25 (paired t test). Normotest showed significantly different values by the methods: P less than 0.001 (paired t test). Kaolin Partial Thromboplastin Time (Activated Partial Thromboplastin Time with kaolin as activator) gave significantly lower vales--the difference was 3 sec--compared with a manual method, and the precision was considerably improved.

Blood Coagulation Tests↗

PubMed1983

The role of cellular cooperation in thromboplastin synthesis.

Increasing evidence [1, 2, 3] demonstrates the clinical importance of monocyte thromboplastin synthesis in the pathogenesis of thrombosis and disseminated intravascular coagulation. Among the first to describe this was the group of the late F Josso [4, 5]. In addition, monocytes and macrophages appear to contribute to fibrin deposition in inflammatory lesions [6, 7]. Several procoagulant substances have been reported to appear in monocyte cultures. Among these, thromboplastin is the most potent and probably also the most important and well studied. Based as it is on our own work, this brief review will deal only with thromboplastin. It is a phospholipid-protein complex, consisting in human material of one species of protein (apoprotein III) mol. wt. approximately 52,000 surrounded by phospholipids [8] in an optimal molecular ratio of apoprotein:phospholipids of approximately 1:80 [9]. Apoprotein III is an integral membrane glycoprotein which apparently is located mainly on the outside of the plasma membrane. The molecular weight has recently been confirmed in our laboratory by Western blotting, using a monoclonal antibody to apoprotein III developed here (Johnsen, unpublished).

Animals↗

PubMed1983

[Standardization problems in the monitoring of oral anticoagulants by Quick's thromboplastin time: an attempt to determine the state of the problem in Switzerland].

In comparison with British Comparative Thromboplastin, we examined 11 different reagents which are presently available in Switzerland for surveillance of oral anticoagulation. Frozen plasma samples obtained from 50 patients under oral anticoagulation for at least 6 weeks were used for comparison of the various reagents. From our results the following conclusions emerge: Our present results largely concur with those of a similar study which compared the therapeutic range of thromboplastin reagents available in Switzerland 6 years earlier; therefore, we assume that the reagents which were sold at that time and are now available in Switzerland have remained fairly constant. In contrast to this apparent agreement, the therapeutic ranges indicated by the producers of reagents are, at least in part, comparable neither with the therapeutic range established for the British Comparative Reagent nor among themselves. Thus, the intensity of the induced coagulation defect is obviously variable, depending on a given test system. The calculated "therapeutic range" for a given test system traditionally corresponds to an average risk of thrombosis or bleeding; this range is not of necessity identical with a target zone that has to be established either individually or for certain diseases. Once established, a target value defining the intensity of oral anticoagulation can be more conveniently reproduced by use of suitable control plasmas rather than with reference thromboplastins, at any rate by practitioners or non specialised hospital laboratories.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗

PubMed1984

Activated partial thromboplastin time of owl monkey (Aotus trivirgatus) plasma.

Owl monkey plasma samples produced short, reproducible activated partial thromboplastin times, similar to those obtained with samples from many other mammalian species. This was an apparent contradiction to an earlier report of long irreproducible activated partial thromboplastin times from owl monkey samples. The discrepant data could not be explained by differences in anticoagulants (citrate or oxalate), assay reagents (partial thromboplastin with either diatomaceous earth or ellagic acid), or activation incubation times (2, 5, or 10 minutes); nor could they be explained by differences in the monkeys' sex, age or previous experimental exposure to Plasmodium falciparum malaria.

Animals↗

PubMed1981

[Effect of modifications of the protein moiety of thromboplastin (factor III) on its activity].

The role of protein moiety of tissue thromboplastin under its specific enzymatic modification and the effects of some protease inhibitors were studied. Treatment with HCl, pepsin and papain was followed by a decrease in the biological activity of thromboplastin, which was unaffected by the inhibitors of some proteolytic enzymes (DFP, monoiodoacetate and o-phenanthroline). It was assumed that the protein component of thromboplastin fulfils a structural function in the assembly of the lipoprotein matrix, on which surface the enzymatic reactions of blood coagulation are known to occur.

Humans↗

PubMed1983

Calibration of reference thromboplastins and standardisation of the prothrombin time ratio.

Thromboplastins vary in their sensitivity to the haemostatic defect induced by oral anticoagulants. To provide a means of standardising prothrombin time tests, the World Health Organization adopted in 1977 a scheme for calibrating thromboplastins in terms of an International Reference Preparation. Unfortunately, the model on which this scheme was based does not always hold. A revised calibration model has therefore been developed and this has been tested in a recent collaborative study. The revised model, which retains fundamentally the same principle for standardising prothrombin time tests, has proved suitable for calibrating thromboplastins of different species and types and, moreover, has certain statistical advantages over its predecessor. In September 1982, the WHO Expert Committee on Biological Standardization adopted the revised model. This paper explains the nature and rationale of this change and considers its practical implications.

Blood Coagulation Disorders↗

PubMed1981

Factor IX alloantibodies shorten the bovine thromboplastin coagulation time of normal human plasma.

We 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 BM, 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.

Animals↗

PubMed1981

Effect of thromboplastin and instrumentation on the prothrombin time test.

Prothrombin time was measured in three different plasma samples by 2580 laboratories in the 1977 CAP Proficiency Testing Program. Analysis of variance was used to show that instrument, as well as thromboplastin, has a significant effect upon observed prothrombin time. In addition, the instrument and thromboplastin effects were estimated, and all were shown to be linearly related to the prothrombin time of the plasma sample. This linear relationship was used to develop a formula for adjusting/correcting an observed prothrombin time for both the thromboplastin and instrument effect. This adjustment/correction method seems promising on the basis of its use in four different sets of data.

Hematologic Tests↗

PubMed1995

The strong positive correlation between factor VII clotting activity using bovine thromboplastin and the activated factor VII level.

We compared factor VII clotting activity (FVIIc) assays using different thromboplastins to determine which is the most sensitive for activated FVII (FVIIa) or for FVII antigen (FVIIag). FVIIc levels were measured using thromboplastins derived from bovine brain (FVIIc Bov), human placenta (FVIIc Hum), and rabbit brain (FVIIc Rab). FVIIa levels were measured by fluorogenic assays using human soluble tissue factor (rsTF) or bovine rsTF. We also measured FVII activity by an amidolytic assay (FVIIc:am Hum) using human thromboplastin and a chromogenic substrate for thrombin. FVIIag levels were determined by ELISA. In the FVIIa assay, the reaction time obtained from using bovine rsTF was shorter than that with human rsTF, suggesting that the interaction of plasma FVIIa with bovine rsTF was stronger than with human rsTF. The plasma FVIIa levels measured using human rsTF and bovine rsTF were almost the same (r = 0.947, p < 0.0001). Among the three FVIIc assays, FVIIc Bov had the strongest positive correlation with the plasma FVIIa level (r = 0.886, p < 0.0001), but had no correlation with FVIIag. An increase of 1 ng/ml in the plasma FVIIa level yielded a 27.9% increase of FVIIc Bov. Plasma FVIIc Hum and FVIIc:am Hum showed moderate correlations with both FVIIa (r = 0.520, p < 0.02 and r = 0.569, p < 0.01, respectively) and FVIIag (r = 0.438, p < 0.05 and r = 0.468, p < 0.05, respectively). FVIIc Rab had the lowest correlation with FVIIa (r = 0.367, p < 0.1), but had a moderate correlation with FVIIag (r = 0.436, p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1993

International standardization of laboratory control of oral anticoagulant therapy: a survey of thromboplastin reagents used for prothrombin time testing.

The prothrombin time (PT) test is the primary measurement in the laboratory control of oral anticoagulant treatment. The traditional expression of PT test results, either as percentage prothrombin activity or PT ratio, is inadequate for international communication and comparison because the values depend on the nature of the thromboplastin test system used. The WHO recommended universal scale of reporting PT results is based on calibration of local thromboplastin systems against an international reference preparation. This scale is the International Normalized Ratio (INR). Application of the INR scale in clinical practice should be encouraged by External Quality Assessment (EQA) schemes, which improve its precision. Many physicians are insufficiently aware of the different sensitivities of rabbit thromboplastins, which result in different anticoagulation intensities being employed in different clinics. Improvement in the situation can only be achieved by continuous education. The more widespread use of the INR scale should facilitate international comparison of anticoagulation results and eventually consensus on optimal target values. The introduction of the INR to countries not already using it, particularly the USA, should be strongly encouraged by all physicians with an interest in anticoagulation and especially those undertaking the long-term management of patients with prosthetic heart valves.

Animals↗

PubMed1994

The response of Quick's prothrombin time test to oral anticoagulation. Influence of thromboplastin source and calcium chloride concentration.

The response of the prothrombin time to oral anticoagulant treatment depends on the thromboplastin reagent and method of testing. A prothrombin time assay system may be characterized by its international sensitivity index (ISI) with which a coumarin-treated patient's international normalized ratio can be calculated. Both the anticoagulant (sodium oxalate or sodium citrate) and calcium chloride concentrations influenced the ISI. An ISI of 2.0 was obtained for Quick's prothrombin time assay using rabbit brain thromboplastin. Replacing rabbit brain by human brain thromboplastin (Aggeler's method) resulted in an ISI of 1.3. The results described herein are mainly of historical interest and may assist in the interpretation of anticoagulation intensity in early American recommendations.

Administration, Oral↗

PubMed1993

Decentralized testing for prothrombin time and activated partial thromboplastin time using a dry chemistry portable analyzer.

Previous work has established the precision and accuracy of a portable blood coagulation analysis system using paramagnetic particles contained in a dry reagent on a disposable test card. We examined the deployment of this technology in decentralized hospital settings and compared test results obtained in the surgical intensive care unit, coronary care unit, and outpatient cardiology clinic with those obtained in the central laboratory. Nursing personnel were instructed in the use of the system, and quality control testing was performed daily by the laboratory staff. In the intensive care units, patient subjects included those on whom tests of prothrombin time and activated partial thromboplastin time had been ordered. Immediate determinations were performed by the intensive care unit nursing staff on the same citrated, whole-blood samples that were subsequently sent to the central laboratory. In the outpatient cardiology clinic, fingerstick blood samples were obtained for prothrombin time determinations with the dry chemistry system. Paired prothrombin time samples obtained by venipuncture were run in the hospital laboratory. The study involved multiple users, multiple locations, two lots of activated partial thromboplastin time cards, and several different instruments, over an extended period. Correlation coefficients between the dry chemistry system and the hospital laboratory under these conditions were in an acceptable range in all sites studied. We concluded that, with appropriate training and quality assurance, the dry chemistry system provides an acceptable alternative to the hospital laboratory for prothrombin time and activated partial thromboplastin time determinations.

Chemistry Techniques, Analytical↗

PubMed1998

The European Concerted Action on Anticoagulation (ECAA): field studies of coagulometer effects on the ISI of ECAA thromboplastins.

Local calibration studies have been performed with lyophilized plasmas at 155 European laboratories to assess coagulometer effects on manual ISI of ECAA thromboplastins (low ISI human recombinant and high ISI rabbit brain). Common sets of 7 normal and 20 artificially depleted lyophilized plasmas were tested with the thromboplastins in the routine local coagulometers. With the human reagent, marked lowering of the manual ISI resulted with most coagulometers, which was associated with disproportionate shortening of the normals. Where this shortening did not occur, there was little coagulometer effect on the ISI. With the rabbit reagent, proportionate shortening with both normal and abnormal plasmas occurred in most instruments with little effect on ISI. INR correction by local ISI assignment appeared successful with the ECAA human reagent. There was negligible INR correction from local calibration of the ECAA rabbit reagent in coagulometers where thromboplastin ISI were unchanged from the ECAA established manual values.

Animals↗

PubMed1979

Interactions among Hageman factor, plasma prekallikrein, high molecular weight kininogen, and plasma thromboplastin antecedent.

To investigate the earliest steps of the intrinsic clotting pathway, Hageman factor (Factor XII) was exposed to Sephadex gels to which ellagic acid had been adsorbed; Hageman factor was then separated from the gels and studied in the fluid phase. Sephadex-ellagic acid-exposed Hageman factor, whether purified or in plasma, activated plasma thromboplastin antecedent, but only when high molecular weight kininogen was presnet. In the absence of plasma prekallikrein, maximal activation of plasma thromboplastin antecedent was slightly delayed in plasma, a delay not observed with similarly treated purified Hageman factor. Thus, high molecular weight kininogen was needed for expression of Hageman factor's clot-promoting properties and plasma prekallikrein played a minor role in the interaction of ellagic acid-treated Hageman factor and plasma thromboplastin antecedent.

Blood Coagulation↗

PubMed1994

Characteristic effects of activated human protein C on tissue thromboplastin-induced disseminated intravascular coagulation in rabbits.

Protein C (PC) is the zymogen of an anticoagulant serine protease and is converted to its active form (activated protein C: APC) by thrombin in the presence of thrombomodulin. APC plays an important role in regulating thrombosis and fibrinolysis by inhibiting not only blood coagulation factors Va and VIIIa but also type-1 plasminogen activator inhibitor (PAI-1). In the present study we examined the effects of human APC on tissue thromboplastin-induced disseminated intravascular coagulation (DIC) in rabbits and compared them with those of heparin. Both APC (300-3000 U/kg) and heparin (100-300 IU/kg) inhibited the decreases in platelet count and fibrinogen level equally. APC improved the prolonged bleeding time, but heparin aggravated bleeding with potent prolongation of activated partial thromboplastin time (APTT). Furthermore, in APC-treated animals, fibrin deposition in glomeruli was less than in heparin-treated animals. This result that APC accelerated local fibrinolysis by neutralizing PAI-1. From our findings, we concluded that APC can improve both coagulation and fibrinolysis in a DIC model and should be useful for the clinical remedy of DIC without having an adverse side effect like a bleeding tendency.

Animals↗