Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Prothrombin”

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 1,369 records · Page 76Linked to original sources
PubMed1987

Augmented Hageman factor and prolactin titers, enhanced cold activation of factor VII, and spontaneous shortening of prothrombin time in survivors of myocardial infarction.

Hyperestrogenemia has been implicated in the pathophysiology of myocardial infarction. Because marked augmentation of the titer of Hageman factor is brought about by the administration of estrogens in humans and by prolactin or estrogen infusion in hypophysectomized rats, we measured the plasma concentrations of estradiol, prolactin, and clotting factors participating in surface-mediated reactions of coagulation in survivors of myocardial infarction. We observed higher titers of Hageman factor, prolactin, and high molecular weight kininogen but no significant change in estradiol or prekallikrein in survivors of myocardial infarction compared with controls. The titer of Hageman factor tended to be directly associated with the prolactin titer. We also report an increase in factor VII activity and spontaneous shortening of prothrombin time in the cold-stored plasma of survivors of myocardial infarction. In such individuals as well as in the control group, the titer of Hageman factor appeared to be responsible for half of the observed increase in factor VII activity and two thirds of the observed shortening of prothrombin time. These data indicate that although the titer of Hageman factor strongly influences the cold activation of factor VII, other factors may affect these phenomena.

Aged↗
PubMed1986

[Methodological aspects of the photometric determination of prothrombin time using chromogenic substrates].

A method for photometric determination of prothrombin time (PT) with a chromogenic peptide as substrate is described. The reagent contains human placental thromboplastin, a chromogenic substrate, calcium, a heparin antagonist and buffer. The new prothrombin time method has been calibrated against international reference preparations for thromboplastin. The reagent is sensitive to deficiency of all coagulation factors of the extrinsic pathway. However, it is not sensitive for heparin up to 1 IU/ml. The precision of this fast and simple method is comparable to that of mechanised assays for clinical chemistry.

Blood Coagulation↗
PubMed1985

Prothrombin time proficiency testing: a robust grading method.

A robust two-way analysis of variance technique was applied to determine simultaneously the effects of method and thromboplastin on prothrombin time. A new approach to outlier detection for two-way analysis of variance was used. Focusing on the underlying error structure improved the uniformity of the grading procedure in the hematology proficiency testing program of the New York State Department of Health. The logarithm-transformed scale produced constancy of error variance and resulted in uniformity of the acceptable spread of data. The common variance was lower than that obtained by previous methods and allowed for a narrower acceptable range of reported prothrombin times by reducing the inflated standard deviation, thus improving the efficiency of the grading procedure. For proficiency testing, no advantage was found in the use of either a common thromboplastin or freeze-dried, coumadinized patient plasmas rather than artificially depleted commercial plasmas, except for special purposes.

Automation↗
PubMed1979

The carbohydrate of bovine prothrombin. Occurrence of Gal beta 1 leads to 3GlcNAc grouping in asparagine-linked sugar chains.

Bovine prothrombin contains three asparagine-linked sugar chains in 1 molecule. The sugar chains were quantitatively released from the polypeptide backbone by hydrazinolysis. All of the oligosaccharides thus obtained contain N-acetylneuraminic acid. Sialidase treatment of these acidic oligosaccharides released three isomeric oligosaccharides, N-1, N-2 and N-3. N-3 was a typical complex type asparagine-linked sugar chain widely found in other glycoprotein, while N-1 and N-2 were unique, because they contain Gal beta 1 leads to 3GlcNAc grouping in the outer chain moiety. By comparing the data of methylation analysis of the acidic oligosaccharides before and after sialidase treatment, the structures of the sugar chains of bovine prothrombin were confirmed as a mixture of NeuAc alpha 2 leads to 6Gal beta 1 leads to 4GlcNAc beta 1 leads to 2Man alpha 1 leads to 6(NeuAc alpha 2 leads to 6Gal beta 1 leads to 4GlcNAc beta 1 leads to 2Man alpha 1 leads to 3)Man beta 1 leads to 4GlcNAc beta 1 leads to 4GlcNAc leads to Asn, NeuAc alpha 2 leads to 6Gal beta 1 leads to 4GlcNAc beta 1 leads to 2Man alpha 1 leads to 6[NeuAc alpha 2 leads to 3Gal beta 1 leads to 3(NeuAc alpha 2 leads to 6)GlcNAc beta 1 leads to 2Man alpha 1 leads to 3]Man beta 1 leads to 4GlcNAc beta 1 leads to 4GlcNAc leads to Asn, NeuAc alpha 2 leads to 3Gal beta 1 leads to 3(NeuAc alpha 2 leads to 6)GlcNAc beta 1 leads to 2Man alpha 1 leads to 6[NeuAc alpha 2 leads to 3Gal beta 1 leads to 3(NeuAc alpha 2 leads to 6)GlcNAc beta 1 leads to 2Man alpha 1 leads to 3]Man beta 1 leads to 4GlcNAc beta 1 leads to 4GlcNAc leads to Asn and their partially desialized forms.

Acetylglucosamine↗
PubMed1979

Metabolism of the coagulation factors of the prothrombin complex in hypothyroidism in man.

The metabolic rate of prothrombin, factors VII, IX and X, was studied in nine hypothyroid patients. Disappearance rates of the four vitamin-K-dependent factors, called the prothrombin complex, were measured after assumedly complete blocking of their synthesis with adequate doses of a coumarin congener (acenocoumarol). Reappearance rates were assessed by induction of synthesis with high doses of vitamin K1 (phytomenadion) when stable hypocoagulability had been achieved. Normal values for these rates were derived from earlier studies in our laboratory. In hypothyroid patients the rates of both disappearance and reappearance were significantly slower for all factors tested. Practical consequences of these observations are discussed. The initial level of factor-IX activity in all nine patients was substantially lower than in normal individuals. Therapy by thyroxine-substitution led to normal levels of factor-IX. This implies a divergency in the retardation of the breakdown and production rates in hypothyroidism. The reappearance rate was indeed found to be more retarded than the disappearance rate.

Adult↗
PubMed1979

Prothrombin time standardization: report of the expert panel on oral anticoagulant control. The International Committee on Thrombosis and Haemostasis, The International Committee for Standardization in Hematology.

In collaborative experiments in 199 laboratories, nine commercial thromboplastins, four thromboplastins held by the National Institute for Biological Standards and Control (NIBS & C), London and the British Comparative Thromboplastin were tested on fresh normal and coumarin plasmas, and on three series of freeze-dried plasmas. One of these was made from coumarin plasmas and the other two were prepared from normal plasmas; in each series, one plasma was normal and the other two represented different degrees of coumarin defect. Each thromboplastin was calibrated against NIBS & C rabbit brain 70/178, from the slope of the line joining the origin to the point of intersection of the mean ratios of coumarin/normal prothrombin times when the ratios obtained with the two thromboplastins on the same fresh plasmas were plotted against each other. From previous evidence, the slopes were calculated which would have been obtained against the NIBS & C "research standard" thromboplastin 67/40, and termed the "calibration constant" of each thromboplastin. Values obtained from the freeze-dried coumarin plasmas gave generally similar results to those from fresh plasmas for all thromboplastins, whereas values from the artificial plasmas agreed with those from fresh plasmas only when similar thromboplastins were being compared. Taking into account the slopes of the calibration lines and the variation between laboratories, precision in obtaining a patient's prothrombin time was similar for all thromboplastins.

Administration, Oral↗
PubMed1981

Chromogenic substrate (S-2222) factor X assays in the follow-up of coumarin treated patients. No advantage over prothrombin time and/or thrombotest.

Factor X was assayed in 30 patients on long-term anticoagulation by means of a chromogenic substrate (S-2222) for a total of 120 determinations. The average level found was 25.38 +/- 9.38% of normal. A satisfactory correlation was found between the factor X chromogenic level and the prothrombin time or Thrombotest percental values. However, factor X levels as determined by the chromogenic assay were usually higher than the global tests percental figures. The factor X chromogenic level was also slightly higher than the RVV-cephalin factor X assay. Since the chromogenic assay does not allow any new information to be made on the coumarin induced defect and since the costs of the assay are about 20-30 times higher than those of a simple prothrombin time, the test seems to play no part in the follow-up of coumarin therapy.

Blood Coagulation Tests↗
PubMed1984

Precursor prothrombin status in two mother-infant pairs following gestational anticonvulsant therapy.

Protein in vitamin K absence (PIVKA) is the prothrombin precursor found in plasma when carboxylation to prothrombin is impaired. We report on two cases in which mother-infant PIVKA concentrations were measured at birth after chronic anticonvulsant therapy during pregnancy. Maternal values were 2.4 and 4%, and infant values 20.0 and 18% in cases 1 and 2, respectively. This demonstrates that, despite the normal coagulation profiles previously described, mothers on chronic anticonvulsant therapy may have a subclinical carboxylation defect, while their infants are at risk for hemorrhagic disease. Estimation of maternal PIVKA levels may be of value for predicting risk of hemorrhage in the neonate.

Adult↗
PubMed1984

[Study of thrombus resistance of materials using the prothrombin consumption test].

The work presents a simple and informative method of the assessment of thromboresistivity of opaque materials by the test of determination of prothrombin consumption in vitro. The average time of prothrombin consumption in the blood after its contact with a glass was 136 +/- 13,3 sec., after the contact with a siliconized glass it was 62 +/- 3,45 sec. which suggests higher thromboresistivity of silicon. The difference of the indices is highly significant (P less than 0,001). A conclusion is made that the method concerned is a reliable one.

Glass↗
PubMed1984

[Evaluation of a new chromogenic method for measuring prothrombin time in the control of oral anticoagulant therapy].

In this study we compared a new chromogenic prothrombin assay, utilizing Chromozym TH, with some commercially available test system commonly used for monitoring oral anticoagulant (OA) therapy. The chromogenic assay has been applied to the Multistat III. In 75 patients attending OA therapy it showed excellent correlation and good diagnostic correspondence to the other methods. The present results indicate that the chromogenic prothrombin assay could be a worthful tool in monitoring OA therapy.

Anticoagulants↗
PubMed1976

Prothrombin determination by means of a chromogenic peptide substrate.

A two stage method to determine prothrombin with the chromogenic peptide substrate benzoyl-phe-val-arg-p-nitroanilide has been worked out. Citrated plasma (10 mul) was diluted in 600 mul tris buffer, pH 8.2, ionic strength 0.18 and activated with 250 mul of a commercial rabbit brain-lung thromboplastin. After 325 s incubation at 37 degrees C 200 mul of a 1 mM solution of the chromogenic substrate was added and the increase in absorbance was recorded in a LKB-Beckman 8600 enzyme analyzer. A reading time of 1 minute (including a delay of 20 s) was used which permitted 55 analyses per hour to be carried out. An approximate linear relationship was found between delta A/min and dilutions of normal plasma in prothrombin deficient plasma. The method is insensitive to variations of factors V, VII and X. Less than 10% or normal plasma was needed to "normalize" plasmas deficient in factor V or VII or X. A group of 99 dicoumarol treated patients and 23 normal subjects has been investigated using the present method and compared with a factor II-VII-X determination method. A correlation coefficient of 0.95 was found.

Dicumarol↗
PubMed1983

Effect of aspirin and sodium salicylate on thrombosis, fibrinolysis, prothrombin time, and platelet survival In rabbits with indwelling aortic catheters.

We have studied the effect of different doses of aspirin on platelet function, PGI2 formation, platelet survival, thrombosis, fibrinolysis, and prothrombin time in rabbits with indwelling aortic catheters. The thrombi formed around indwelling aortic catheters were found to have a large fibrin component, and their formation was inhibited by heparin administration. Thus, in these experiments we examined the effect of aspirin (a weak inhibitor of thrombin-mediated platelet aggregation) under conditions in which thrombin was a major factor in the initiation and growth of the thrombi. Only very high doses of aspirin tended to inhibit thrombus formation over the 5-day period of observation, and a statistically significant inhibition of thrombus formation was produced by equivalent concentrations of sodium salicylate. The failure of high doses of aspirin to achieve a significant inhibition of thrombosis under the conditions of these experiments (whereas an equivalent dose of sodium salicylate was inhibitory) could be due to aspirin inhibition of PGI2 formation. Shortened platelet survival was not affected by aspirin treatment or the dose sodium salicylate that inhibited thrombus formation. The tendency to inhibit thrombus formation appeared to be unrelated to an effect on platelets but was associated with prolongation of the one-stage prothrombin time and increased whole blood fibrinolytic activity; doses of aspirin that inhibited platelet aggregation in response to sodium arachidonate or collagen, and PGI2 formation by the vessel wall, did not have a significant effect on the amount of thrombus present at 5 days. However, the high doses of aspirin that inhibited PGI2 formation were associated with a tendency to increased thrombus formation during the first 3 hr after insertion of the catheter. The results of these experiments show that when thrombin is an important factor in the formation of thrombi, aspirin is a weak inhibitor of thrombosis unless doses are used that provide sufficient salicylate to interfere with blood coagulation and promote whole blood fibrinolytic activity. These results also show that thrombus formation can be inhibited without an apparent change in platelet survival.

Animals↗
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↗
PubMed1982

The coagulant-active phospholipid content is a major determinant of in vivo thrombogenicity of prothrombin complex (Factor IX) concentrates in rabbits.

In vitro evaluation of prothrombin complex concentrates in a thrombin generation assay, using DAPA and purified components of the prothrombinase complex, demonstrated significant levels of coagulant-active "phospholipid replacing" activity. Quantification of this activity showed a significant correlation (r = 0.8747, p less than 0.01) with thrombogenicity measured in vivo in a stasis model in rabbits. Extracted lipid material retained full phospholipid replacing activity in the vitro assay. Thin-layer chromatographic characterization confirmed the presence of phospholipids with known coagulant activity in vitro. In vivo, the extracted material was nonthrombogenic but augmented the thrombogenicity of purified factor Xa. Substitution of a synthetic coagulant-active phospholipid (phosphatidylcholine-phosphatidylserine lipid vesicles) for the extracted phospholipid produced a similar augmentation of a factor-Xa-induced thrombogenicity in vivo. It is concluded that the coagulant-active phospholipid content of prothrombin complex concentrates is a major determinant of thrombogenicity but requires the presence of activated clotting factors for its expression in vivo.

Animals↗
PubMed1982

Prothrombin antigen and coagulant activity in patients with liver disease.

Plasma levels of prothrombin immunoreactive protein (factor II antigen) (II-Ag) and coagulant activity (II-CA) were determined in eight patients with acute hepatitis and in 29 patients with chronic liver disease (cirrhosis). The II-CA was reduced in 23 (62%), II-Ag in 17 (46%), and both were reduced in 13 (36%) of the cases. A disproportionate reduction was noted in 21 (57%); ie, there was more II-Ag found in comparison to the corresponding level of II-Ca. Ninety-six percent (23) of 24 patients with moderate to severe hepatocellular disease showed reduced II-CA levels; 63% (15) showed reduced II-Ag levels, with a disproportionate reduction in II-CA in 67% (16). These data suggest that reduced synthesis as well as impaired carboxylation of prothrombin precursor protein are factors contributing to the coagulopathy in patients with moderate to severe liver disease and that measurement of circulating levels of II-Ag may provide an excellent indication of hepatic synthetic capacity.

Adolescent↗
PubMed1981

[Components of the prothrombin molecule during development of avitaminosis K].

Components of the blood plasma prothrombin molecule were studied in the course of alimentary K avitaminosis development in pigeons and rats. A gradual decrease in the content of hexosamines in the prothrombin molecule was observed when vitamin K was excluded from the animals' diet. This decrease may be associated with inhibition of glucosamine biosynthesis.

Animals↗
PubMed1980

Crystallization and preliminary X-ray data of proteins derived from prothrombin.

Crystals of bovine prothrombin fragment 1 and deglycosylated fragment 1 have been grown from polyethylene glycol, Tris/maleate solutions and the crystals scatter x-rays at 2.8 A resolution. The crystals of both are tetragonal, space group P41212 or P43212, with 1 molecule per asymmetric unit. Moreover, the two appear to be isomorphous. Since the mother liquor can support Ca2+ ion without precipitation, crystals have been soaked with Ca2+ ion and preliminary results indicate that these remain closely isomorphous with parent crystals. Isomorphous heavy atom derivatives of mercury and platinum have been prepared of glycosylated fragment 1. In addition, crystals of human prothrombin fragment 1 have also been grown.

Animals↗