Search PubMed⌕ Search

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.

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

At least 163 records · Page 9Linked to original sources
PubMed1990

[Standardization of the thromboplastin time determination].

The results of our studies prove that today it is possible for manufacturers of thromboplastin preparations to follow the international recommendations for standardization of methods for prothrombin time determination. This is valid not only for the PT reagents for coagulometric techniques but also for those for photometric techniques. New manufacturing processes allow to produce sensitive thromboplastins which can be calibrated according to the recommendations of international standardization committees. Calibrated thromboplastins enable introduction of a common scale (INR) for the control of the intensity of the oral anticoagulation. The INR system improves the comparability of the therapeutical ranges recommended from different organizations and from manufacturers of thromboplastin, so that the continuity of the oral anticoagulant therapy of patients even in different countries will be decisively improved.

Calibration↗
PubMedDate not supplied

[Partial purification of tissue thromboplastin by the gel filtration method and its use for reproducing the generalized decompensated thrombinogenesis syndrome].

Tissue thromboplastin was purified using various chromatographic resins: Sephadex G-200, Ultragel AcA 34, Acrylex P-300 and Toyopearl HW-55F. The purity of the preparations obtained was evaluated by means of the ratio of the thromboplastin solutions absorbency at 540 nm and a protein concentration in the solution expressed as mg/ml. The most purified preparations of tissue thromboplastin were obtained after gel filtration on Toyopearl HW-55F. The thromboplastin preparation produced was used for experimental reproduction of the syndrome of generalized decompensated thrombinogenesis.

Animals↗
PubMedDate not supplied

[The role of lipid peroxidation in the process of thermal inactivation of tissue thromboplastin].

Thermic inactivation of tissue thromboplastin in air led to an increase in concentration of malonic dialdehyde and to decrease in activity of thromboplastin. Thromboplastin, treated with ionol, exhibited a less distinct loss of the hemocoagulation activity on heating. Inactivation of the tissue thromboplastin in air during thermic treatment involved at least three steps: thermic denaturation of apoprotein III, lipid peroxidation of the lipid component, observed in the experiment, oxidation of apoprotein III and destruction of its lipid moiety.

Animals↗
PubMed1979

The antithrombotic effects of warfarin and heparin following infusions of tissue thromboplastin in rabbits: clinical implications.

An animal model for the production of stasis thrombi was employed to obtain the data reported in this study. Rabbits treated with warfarin (1.5 mg/kg/day) exhibited a maximal increase in prothrombin time and decreases in factor VII, factor X, and prothrombin within 48 hr with no additional changes occurring after 10 days of drug administration. In contrast, Xa inhibitory activity was unchanged after 48 hr of warfarin treatment but was significantly increased by the tenth day. When thrombosis was induced by infusions of 60 micrograms of tissue thromboplastin, the warfarin regimen produced an antithrombotic effect by the sixth hour, which increased to significance by day 2 and was further significantly increased by day 10. These three stages correspond to the initial depletion of the vitamin K-dependent clotting factors, the maximal depletion of these proteins, and the maximal increase in Xa inhibitory activity, respectively. Thus these experiments separate the antithrombotic potential of warfarin into two components: an early effect related to the decrease in factor VII and a delayed augmentation of Xa inhibitory acticity. Intravenous heparin alone (5 U/kg) did not protect against infusions of 60 micrograms of tissue thromboplastin but did provide an antithrombotic effect against 45 micrograms of the same infusate. Higher doses of heparin, however, did protect against infusion of 60 micrograms of tissue thromboplastin. After 48 hr of warfarin treatment, 5 U/kg heparin increased protection against 60 micrograms of tissue thromboplastin to a degree equivalent to that provided after 10 days of warfarin therapy alone.

Animals↗
PubMed1978

The effect of heparin on the activated partial thromboplastin time.

Data from the 1976 and 1977 CAP surveys were analyzed for response of the activated partial thromboplastin time (APTT) to heparin. Different sources and concentrations of heparin were used. The results indicate that the precision of the APTT is more dependent on instrumentation than on partial thromboplastin. This was true for all four of the heparinized specimens evaluated. A single exception was found with the "old" Dade reagent activated cephaloplastin. The mean difference in the activated partial thromboplastin times obtained with differing concentrations of heparin was entirely dependent on the partial thromboplastin reagent used. No significant difference in the results was found when equal concentrations of bovine lung and porcine intestinal mucosal heparin were compared.

Animals↗
PubMed1983

Regulation of thromboplastin synthesis in mouse placental cells in vitro.

Mouse placental cells are probably constitutive producers of the thromboplastin apoprotein in vitro. The effect of cyclic AMP-elevating compounds on their expression of thromboplastin activity has been studied. Dibutyryl cyclic AMP, the phosphodiesterase inhibitor Ro 20-1724 and the adenyl cyclase stimulator forskolin all decrease the synthesis of thromboplastin. Prostaglandin E2 and the phosphodiesterase inhibitor butyl-methyl-xanthine have a biphasic dose dependent effect. A stimulation was observed at low concentrations, whereas higher doses decreased the synthesis of thromboplastin. Adrenaline had no effect. Combination of two compounds, each at maximally inhibiting concentration gave no significant additive inhibitory effect, showing that they probably act via the same pathway.

1-Methyl-3-isobutylxanthine↗
PubMed1977

Comparison between British Comparative Thromboplastin (BCT) and a factor II-VII-X determination method (simplastin A) based on fresh plasma samples from dicoumarol-treated patients.

Comparisons between British Comparative Thromboplastic (BCT) and a factor II-VII-X determination method--Simplastic A--have been carried out monthly during the time from December 1973 to March 1976. On each occasion fresh plasma from 20 dicoumarol-treated patients was analyzed with the two methods. It was found that the linear regression model is well suited for the comparison, that the BCT thromboplastin did not change significantly during the study, and that the method of comparing has a coefficient of variation of approximately 6-8%. This means, for instance, that a ratio of 3.8 with BCT corresponds to a ratio of 3.5 +/- 0.26 with Simplastin A. Thus in one period you may have ratio 3 and in another ratio 4 as the lower limit of the therapeutic range although you use the same thromboplastin and the same method. The importance of having a stable reference thromboplastin and an established method of comparing thromboplastins is stressed.

Blood Coagulation Tests↗
PubMed1983

Use of activated partial thromboplastin time to monitor coumarin anticoagulation.

The activated partial thromboplastin time after heparin removal (aPTT/HR) is an anionexchange procedure that permits the unobstructed monitoring of the progress of coumarin anticoagulation by removing interfering heparin. An all-intrinsic-pathway anticoagulant surveillance scheme based upon the aPTT/HR has been proposed and provisionally tested. The adoption of the new scheme will depend upon the identification of partial thromboplastins that are as predictable and reliable as the tissue thromboplastins in modern one-stage prothrombin times. In this study, the commercial APTT Reagent and Simplastin performed with equal sensitivity and specificity when evaluated by means of prothrombin group factor assays on coumarintreated subject plasmas. It is concluded that this commercial partial thromboplastin (1) is capable of being used for the purpose of following heparin, heparin plus coumarin, and coumarin anticoagulation; (2) is potentially able to identify more of the inherited and acquired derangements that can lead to anticoagulation-associated hemorrhage; and (3) is a universally available alternative to the traditional anticoagulant monitoring approach.

Blood Coagulation Tests↗
PubMed1982

The role of factor IX in tissue thromboplastin induced coagulation.

Tissue thromboplastin apoprotein was partially purified from human brain. The apoprotein was recombined with mixed phospholipids to yield active thromboplastin. The recombined thromboplastin induced proteolytic activation of isolated human factor IX in the presence of factor VII and Ca2+. The clotting times of various deficient plasmas were determined as a function of apoprotein concentration, keeping the phospholipid concentration constant. The clotting times of a factor XII-deficient plasma were the same as those of a factor XII/factor IX-deficient plasma, except at very low apoprotein concentrations. However, under those conditions the difference in clotting times was independent of the presence of anti-factor VII serum. Similar observations were made for factor XI-deficient plasma in comparison with factor XI/factor IX-deficient plasma. These results indicate that activation of factor IX by factor VII/tissue thromboplastin does not significantly contribute to plasma coagulation.

Apoproteins↗
PubMed1993

[Initial experiences with a recombinant human tissue thromboplastin in oral anticoagulation].

A recombinant tissue factor (rTF, Batch TFS-RD3, Baxter Diagnostics) has been assessed by plasma and capillary blood methods and compared with our working rabbit brain thromboplastin (CRB Roche, Basel, Switzerland) for its suitability in monitoring oral anticoagulant therapy. The international sensitivity index (ISI) for rTF calibrated against CRB has been found to be 0.73 and 0.69 respectively. The slope of the orthogonal regression line between log prothrombin time rTF plasma and rTF capillary blood is 0.96. Thus, we considered the ISI to be identical for both methods. International normalized ratios calculated with these assumptions, and even activity percentages assigned by a dilution curve, did not differ from the results obtained with our working thromboplastin. The human recombinant thromboplastin TFS-RD3 seems to have properties similar to currently used commercial thromboplastins. Recombinant tissue factor as a well defined preparation could make essential contributions to the standardization of prothrombin time and to the improvement of oral anticoagulant therapy.

Animals↗
PubMed1996

Comparison between recombinant and rabbit thromboplastin in the management of patients on oral anticoagulant therapy.

The aim of this study was to compare recombinant thromboplastin (rTF, ISI = 0.82) with rabbit thromboplastin (RT, ISI = 1.46) in order to evaluate which performed better in our thrombosis centre. To this purpose we randomized 67 patients to be double-blind monitored in two groups for three months either with PT performed with RT or with PT performed with rTF. After this period each patient was shifted to the other group. We considered the following as end points of the study: percentages of PT results within the therapeutic range, number of visits and therapeutic dose adjustments per patient. The "last check in file" method was used to evaluate the laboratory quality of oral anticoagulation for both thromboplastins. The results show that there was no difference in the number of visits per patient between the two groups: 6.9 +/- 1.7 in the rTF group versus 7.3 +/- 1.9 in the RT group (p = 0.19). The variations of therapeutic dose per patient were not different in the two groups: the dose was changed once (range 0-8) in the rTF group and once (range 0-11) in the RT group (p = 0.15). The percentages of PT results within the therapeutic range were not different between the two groups. The "last check in file" method showed similar percentages in both groups: PT results in the therapeutic range were 67.2% in the RT group and 68.8% in the rTF group. We conclude that the two thromboplastins had a similar effect on the end points of the study in spite of the relatively high ISI of the RT.

Administration, Oral↗
PubMed1995

Multi-center calibration of the third BCR reference material for thromboplastin, rabbit, plain, coded CRM 149S. Long-term stability of previous BCR reference materials.

In a collaborative study by eleven laboratories performed within the framework of the European Community Bureau of Reference (BCR), a third reference material for thromboplastin, rabbit, plain, has been calibrated against RBT/90, the current WHO international reference preparation for thromboplastin, rabbit, plain. This third reference material (coded CRM 149S) has a mean International Sensitivity Index (ISI) of 1.257 with a standard error of the mean of 0.013. The previous BCR reference material for thromboplastin, rabbit, plain (coded CRM 149R) and the reference material for thromboplastin, bovine, combined (coded OBT/79) were also included in the trial for assessment of the long-term stability of the ISI values. The relationship between ISI values determined in the present study was nearly identical to that of the historical values. These results offer reassurance with regard to the long-term stability of these reference materials.

Animals↗
PubMed1965

PARTIAL THROMBOPLASTIN TIME TEST WITH KAOLIN. NORMAL RANGE AND MODIFICATIONS FOR THE DIAGNOSIS OF HAEMOPHILIA AND CHRISTMAS DISEASE.

The partial thromboplastin time test provides a convenient and sensitive screening procedure for deficiencies of thromboplastic factors, especially factors VIII and IX. The test is carried out after preincubating the plasma for 10 minutes with kaolin, and Inosithin is used as a platelet substitute. The ;normal range' of the test has been estimated in terms of the differences encountered between random normal plasmas tested in pairs, because individual patients are usually tested against single control subjects. A patient's partial thromboplastin time should be regarded as abnormal if it is more than six seconds longer than the control time. In the diagnosis of haemophilia, patients' plasmas with concentrations of factor VIII as low as about 20% might be regarded as being within the range of normal, if the selected control subject's factor VIII happened to lie near the lower end of the normal range. When mild haemophilia is suspected, discrimination may be improved by diluting both the patient's and the control plasmas 1 in 20 in haemophilic plasma. With the test modified in this way the clotting time is prolonged, though the range of differences among normal subjects is unaltered, and plasmas with factor VIII concentrations below about 30%, i.e., in undiluted plasma, would be unlikely to be regarded as normal. The partial thromboplastin time may be similarly modified as a screening test for factor IX deficiency.Some clinical examples are reported.

Aged↗
PubMed1979

Factor VII Padua 2: another factor VII abnormality with defective ox brain thromboplastin activation and a complex hereditary pattern.

A new factor VII abnormality is presented. The propositus was a 9-yr-old child who presented a mild bleeding tendency characterized by epistaxis and easy bruising. The parents were not consanguineous, but they came from the same area. The laboratory features were mild prolongation of prothrombin time and P.P. test and normal partial thromboplastin and Stypven cephalin clotting times. The Thrombotest was moderately prolonged. Factor VII was 40%-50% of normal using rabbit or human brain thromboplastin, but only 13%-24% using ox brain thromboplastin. Factor VII cross-reacting material (CRM) was about 50% of normal. The father, a paternal aunt, and a paternal cousin showed similar clinical and laboratory findings. The brother of the propositus, the mother, and other members of her family showed about 50% factor VII activity and CRM and were considered to be heterozygotes for true factor VII deficiency. Similar findings were also present in the father and in the brother of the affected cousin. The defect in the propositus seems to consist of a double heterozygosity between abnormal factor VII and heterozygous factor VII true deficiency. The factor VII abnormality appears to consist of abnormal reactivity toward ox brain tissue thromboplastins and appears to be different from previously described factor VII abnormalities. The name factor VII Paudua2 is proposed for this condition.

Adolescent↗
PubMed1998

Prolonged prothrombin time and activated partial thromboplastin time due to underfilled specimen tubes with 109 mmol/L (3.2%) citrate anticoagulant.

Underfilling of specimen tubes containing 129 mmol/L (3.8%) buffered citrate prolongs prothrombin time (PT) and activated partial thromboplastin time (APTT) values. We studied this phenomenon by using 109 mmol/L (3.2%) buffered citrate as the anticoagulant, anticipating some increase in tolerance to underfilling. Venous blood drawn from 12 healthy subjects and 30 patients receiving long-term oral warfarin therapy was mixed with 109 mmol/L buffered citrate solution in proportions equivalent to filling the collection tubes from 52% to 100% of capacity. Accurate PT values were obtained from normal specimens if the tubes were filled to 65% or more of capacity. Accurate PT results in the therapeutic range were obtained only with filling to 80% or more of capacity (using a "moderately sensitive" thromboplastin reagent, International Sensitivity Index [ISI] = 2.06) or 90% or more of capacity (using a "highly sensitive" thromboplastin reagent, ISI = 1.01). In contrast, APTT was much less tolerant to underfilling, with prolonged values observed in most specimens filled to less than 90% of capacity. No false low values were observed. Specimen tubes should be filled to at least 90% of capacity to avoid falsely elevated PT or APTT results, but values within the reference range may be acceptable even from underfilled tubes.

Adult↗
PubMed1997

Effect of weight, sex, age, clinical diagnosis, and thromboplastin reagent on steady-state intravenous heparin requirements.

BACKGROUND: There is a significant direct relationship between steady-state intravenous heparin dose requirements and total body weight. Less is known about whether sex, age, clinical diagnosis, and the thromboplastin used to measure the activated partial thromboplastin time (aPTT) affect heparin dose requirements. METHODS: Four cohorts of patients treated with intravenous heparin were gathered from 3 hospitals: 2 cohorts with deep vein thrombosis (DVT) and 2 cohorts with coronary artery disease (CAD). For each clinical diagnosis, half the patients were monitored using one aPTT reagent and the remainder were monitored using a second reagent. Heparin doses and aPTT measurements were recorded, and the dose necessary to achieve an aPTT ratio of 2.0 was calculated using a computer software program. RESULTS: We analyzed the records of 340 patients: 165 with DVT and 175 with CAD. Using analysis of variance, there was a significant difference in the steady-state heparin requirements among patients with DVT compared with patients with CAD (P < .001). For each clinical diagnosis, the use of a different thromboplastin reagent did not affect heparin dose requirements (P > .42). Linear regression modeling disclosed that the steady-state heparin dose for patients with DVT was a function of weight plus an effect modifier involving weight and age, whereas for patients with CAD there was only a weak relationship with weight. CONCLUSIONS: Steady-state heparin dose requirements were significantly different in patients with DVT compared with patients with CAD, suggesting that different dosing nomograms are needed for each condition. For patients with DVT, the accuracy of the initial heparin dose estimate may be improved by considering the patient's age and weight.

Aged↗
PubMed1982

The mandatory role of complement in the endotoxin-induced synthesis of tissue thromboplastin in blood monocytes.

Fresh isolated blood cells recombined with normal heparinized plasma and then incubated with endotoxin, induced a 100-fold increase in monocyte tissue thromboplastin synthesis. In contrast, recombination of these cells with heat inactivated plasma, cobra venom factor-treated plasma, Ca2+-free plasma, or BioRex 70-treated plasma (plasma free of Clq and D) before incubation with endotoxin, failed to induce monocyte synthesis of tissue thromboplastin. These results strongly support the hypothesis that complement is required for endotoxin stimulation of blood monocyte synthesis of tissue thromboplastin.

Complement Pathway, Alternative↗
PubMed1982

In vitro effect of phospholipase C from Bacillus cereus on tissue thromboplastin from different species.

Purified phospholipase C from Bacillus cereus caused a significant loss in the procoagulant activity of thromboplastin preparations from man, rabbit, sheep, cow, rat and mouse. However, marked differences were observed with respect to the degree of inactivation. Rat, mouse, bovine and one type of rabbit preparations (prepared from acetone powdered brain) were markedly more sensitive to attack by phospholipase C than were preparations of human, sheep and standard rabbit preparations. The relative amounts of the individual phospholipids in thromboplastin preparations showed only minor variations among the species. The effect of phospholipase C on each of these phospholipids in the various thromboplastin preparations showed some significant differences.

Animals↗