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PubMed1975

The K-test (trypsin clotting time) in coumarin treated patients and in congenital deficiencies and abnormalities of the prothrombin complex.

The behavior of K-test (Trypsin clotting time) has been studied in 38 patients on long-term coumarin therapy and in 19 patients with congenital coagulation disorders of the prothrombin complex. All coumarin treated patients showed a clear prolongation of the test. The results obtained were compared with the standard prothrombin time, the Hepato-Quick-test (P-P test) and the Factor II + X test values, observed in the same patients. A good correlation was observed in each instance. The highest correlation was observed between K-test and the Factor II + X test (r=+0,78;t=7,80;p less than 0.001). All congenital coagulation disorders of the prothrombin complex yielded a prolonged K-test value but for Factor VII deficiency. In three patients with this latter condition a perfectly normal value was obtained. The K-test together with the prothrombin time may be useful in the differential diagnosis of factor VII deficiency from factor X deficiency and from the factor X Friuli abnormality.

Blood Coagulation Disorders↗
PubMedDate not supplied

Viper venoms and coumarin-induced prothrombin. A comparison of several one-stage methods employing three different venoms as thromboplastins.

Three venoms obtained from three vipers, namely Echis carinatus, Notechis scutatus scutatus and Oxyuranus scutellatus, have been used as thromboplastin in a one-stage assay of coumarin-induced prothrombin. Regardless of the venom used, prothrombin resulted to be low in coumarin-treated patients. The mean values obtained were 27.2, 33.6, and 24.2%, respectively. These values were comparable to those obtained by means of the classical one-stage method (24.8%). A good correlation was observed among the different methods. However, the levels observed using the Notechis scutatus scutatus venom method were slightly higher as compared to those obtained by means of the other viper venoms and by means of the classical one-stage method. The three viper venoms used seem unable to activate coumarin-induced prothrombin. The levels obtained were in fact, in each instance, definitely lower than those observed immunologically. Methods which employ these viper venoms may be used in the evaluation of prothrombin in coumarin-treated patients.

Animals↗
PubMed2005

Prothrombin G20210A gene variant is not associated with idiopathic portal vein thrombosis in an area endemic for portal vein thrombosis.

Prothrombin G20210A gene variant has been found in 0-23% of patients with portal vein thrombosis (PVT). This wide variation makes it difficult to assess the importance of prothrombin G20210A gene variant as a predisposing factor for PVT. In this study from South India, none of the patients with idiopathic PVT (0/38) or any of the controls (0/46) had prothrombin G20210A gene variant. Prothrombin G20210A gene variant does not contribute to the development of PVT in India.

Adolescent↗
PubMed2001

Survey of factor V leiden and prothrombin gene mutations in systemic lupus erythematosus.

The two most common hereditary risk factors for thrombosis are factor V Leiden mutation and a prothrombin gene mutation. There is indeed a thrombotic tendency in patients with systemic lupus erythematosis (SLE) and it is not always associated with antiphospholipid antibodies. We aimed to determine the relationship between both factor V Leiden and prothrombin gene mutations and SLE. Using polymerase chain reaction (PCR) the factor V Leiden and prothrombin gene mutations were evaluated in 55 patients (20 children and 35 adults) with SLE. Although seven patients were found to have factor V Leiden mutation in the heterozygous state, two had the heterozygous G-->A (20210) prothrombin gene mutation. Although one had these two mutations concurrently, these two patients did not have thrombosis. The factor V Leiden mutation frequency (12.7%) was higher than that of our general population (7.1%). On the other hand, seven of the patients with SLE had a thrombotic event. Although of these seven, four (57%) had factor V Leiden mutation, three (43%) had no mutation. Of 48 patients with no thrombotic history, only three had the factor V mutation (6.25%). The prevalence of the factor V Leiden mutation in SLE patients with and without thrombosis was significantly different by Fisher's exact test (p<0.05). The risk of venous thrombosis in patients with factor V Leiden increased threefold compared to that in those without factor V Leiden mutation (odds ratio 20.1; CI 2.99-133.6). Although factor V Leiden mutation seems to play a role in the development of venous thrombosis in SLE, the development of thrombosis in SLE is multifactorial.

Adolescent↗
PubMed1975

Biological and immunological activity of prothrombin in rough and smooth microsomes isolated from rat liver.

1. The presence of biological and immunological activity of prothrombin in sonicates from rough and smooth microsomes has been investigated. 2. Biological activity of prothrombin was detected in both the rough and smooth microsomal fraction. The specific and the total activity of prothrombin in the sonicates from smooth microsomes were 3-4-fold higher than in the corresponding fraction from rough microsomes. 3. Prothrombin could be identified in both microsomal fractions by double immunodiffusion. 4. The presence of a macromolecular inhibitor of blood coagulation in the microsomes is reported.

Animals↗
PubMed1989

Effects of venom proteases on peptide chromogenic substrates and bovine prothrombin.

Eighteen proteases were isolated from six hemorrhagic venoms of snakes belonging to the families of Crotalidae and Viperidae. According to their actions, they are classified as thrombin-like enzymes, alpha-fibrinogenases, beta-fibrinogenases, Factor X activator, prothrombin activator, hemorrhagins and esterases. Thrombin-like enzymes, beta-fibrinogenases, hemorrhagins and esterase hydrolyzed Phe-Pip-Arg-pNA (S-2238, substrate for thrombin) more strongly than CBZ-Ile-Glu-Gly-Arg-pNA (S-2222, substrate for Factor Xa), CBZ-Phe-Val-Arg-pNA (B-7632) or CBZ-Pro-Phe-Arg-pNA (B-2133). Thrombin-like enzymes, beta-fibrinogenase and esterase hydrolyzed tosyl-L-arginine methyl ester and benzoyl-L-arginine ethyl ester. S-2238 is the most susceptible chromogenic substrate for most venom proteases. Thrombin-like enzymes degraded prothrombin molecule progressively down to prethrombin 2 while alpha- and beta-fibrinogenases degraded it only to prethrombin 1. Factor X activator of Vipera russelli venom and esterase of T. mucrosquamatus venom did not have any effect on prothrombin. Thus, the effects of venom proteases on prothrombin are not parallel to their amidolytic or esterolytic effects.

Animals↗
PubMedDate not supplied

Warfarin anticoagulation: difficulties in interpretation of the prothrombin time.

Studies of the prothrombin time in normals and patients receiving warfarin therapy revealed a marked shortening of the prothrombin time when the blood was collected in any type of collection tube other than a polypropylene tube. This shortening of the prothrombin time in patients receiving coumadin therapy was time and temperature dependent. This in-vitro shortening of the prothrombin time could lead to serious clinical errors involving dosage of warfarin derivatives to be administered to patients.

Anticoagulants↗
PubMed1984

Abnormal prothrombin in the vitamin K-deficient rat.

Vitamin K is required for the post-translational formation of gamma-carboxyglutamyl residues in the vitamin K-dependent plasma clotting factors. Interference with vitamin K action results in the appearance of undercarboxylated, "abnormal," forms of prothrombin in bovine and human plasma, but the extent of this response in the rat has been controversial. Development of amidolytic and immunochemical assays for rat prothrombin have now shown that plasma from vitamin K-deficient or Warfarin-treated rats contains a non-BaSO4 adsorbable (undercarboxylated) pool of prothrombin that is equivalent to between 5 and 10% of the normal plasma prothrombin concentration.

Animals↗
PubMed1988

Differential effects of activation of prothrombin by streptokinase compared with urokinase and tissue-type plasminogen activator (t-PA).

We have previously reported paradoxical prothrombotic effects manifest by elevations of fibrinopeptide A (FPA) after administration of streptokinase to patients with acute myocardial infarction. To characterize mechanisms responsible and their dependence on streptokinase (SK) as opposed to other activators of the fibrinolytic system, the present study was performed to compare effects of streptokinase, tissue-type plasminogen activator (t-PA), and urokinase on plasma and on purified prothrombin in concentrations similar to those achieved pharmacologically. The effects of plasmin were assessed to determine the extent to which the elevations of FPA seen could be attributed to activation of plasminogen. Elevations of FPA were observed after incubation of each of the activators with citrated plasma at 37 degrees C for 60 minutes. However, they were most marked with streptokinase (64.5 +/- 4.6 pmol FPA/ml (mean +/- SE) with 100 IU SK/ml, and 77.6 +/- 5.0 pmol/ml with 500 IU SK/ml). Elevations of FPA induced by streptokinase were attenuated by 100 IU/ml heparin [15.2 +/- 1.9 pmol/ml after 100 IU of SK (p less than 0.001 compared with results with streptokinase without heparin)]. Human plasmin, 2.5 CTA/ml, caused changes similar to those induced by streptokinase. The minimal elevations of FPA induced by t-PA or urokinase (less than 10 pmol/ml without heparin) were not significantly attenuated by heparin. Incubation of barium citrate adsorbed plasma (vitamin K factor depleted) with streptokinase markedly attenuated elevation of FPA. Addition of prothrombin (1.5 microM) and streptokinase (100 IU/ml) to the barium citrate adsorbed plasma elicited elevations of FPA similar to those induced by streptokinase in citrated plasma. Amidolytic activity with the "thrombin" substrate H-D-phenylalanyl-L-pipecolyl-L-arginine-p-nitroanilide dihydrochloride (S-2238) was evident when streptokinase, plasminogen (0.24 microM), and prothrombin (1.5 microM) were incubated in buffer. Thus, concentrations of streptokinase that are low in terms of therapeutic blood levels activate prothrombin in plasma, likely due to activation of plasminogen. Neither tissue-type plasminogen activator nor urokinase in pharmacologically comparable concentrations increase thrombin activity appreciably perhaps because of less intense activation of plasminogen. Consideration of the prothrombotic effects observed may be relevant to selection of specific agents for therapeutic thrombolysis, to appropriate titration of dose, and to the need for the use of heparin conjointly with particular activators of the fibrinolytic system such as streptokinase.

Fibrin Fibrinogen Degradation Products↗
PubMed1989

Rapid purification of factor IX, factor X and prothrombin by immunoaffinity and ion exchange chromatography.

This study describes a rapid purification of factor IX, factor X and prothrombin by immunoaffinity and ion exchange chromatography. Human factor IX was purified from plasma in 34% yield using barium sulfate adsorption and immunoaffinity purification. The specific clotting activity of purified factor IX was 269 units/mg, with an apparent molecular weight of 57,000 in the presence of sodium dodecyl sulfate on polyacrylamide gels. The immunodepleted, factor-IX deficient plasma was chromatographed on a dextran sulfate agarose column which resolved prothrombin and factor X in highly purified states and with approximately 50% yield. The specific activities of prothrombin and factor X obtained by this procedure were 24 units/mg and 147 units/mg respectively. Both proteins isolated by this method showed a single component on SDS gel electrophoresis and the molecular weights of intact prothrombin and factor X were 72,000 and 67,000 respectively.

Ammonium Sulfate↗
PubMed1990

The prothrombin activation peptide regulates synthesis of the vitamin K-dependent proteins in the rabbit.

The turnover of 125I-bovine prothrombin fragment 1 was studied in the rabbit. The t1/2 of the peptide in the intravascular compartment was 11.5 hours and this compartment accounted for between 7.9 and 14.4% of the injected radioactivity. The rest of the radioactivity was distributed between two compartments in the extravascular space. The injection of the peptide (10 mg/rabbit) was associated with a transient increase in the plasma concentration of prothrombin and of factor X, with maximum concentration of prothrombin between 40 and 66 hours from the injection and between 26 and 40 hours for factor X. It is concluded that the injection of fragment 1 in the rabbit induced a transient increase in the synthesis of the vitamin K-dependent proteins that is compensated for by an increased absolute catabolic rate. It is suggested that the prothrombin activation peptide serves as regulatory message which induces the subsequent restoration of the appropriate concentration of the vitamin K-dependent proteins.

Animals↗
PubMed1993

Comparative effects of enoxaparin and unfractionated heparin in healthy volunteers on prothrombin consumption in whole blood during coagulation, and release of tissue factor pathway inhibitor.

In a randomized crossover study twelve healthy male volunteers (23.5 +/- of 4.8 years, 73.0 +/- 6.4 kg, 180.8 +/- 5.7 cm) received one subcutaneous injection of either enoxaparin (EN) at 40 mg or 1 mg kg-1, or unfractionated heparin (UH) at 5,000 IU at one week intervals. Area under curves (AUC) of Anti-Xa and Anti-IIa activities correlated with EN dose. The relative effectiveness of EN versus UH 5,000 U as assessed by AUC ratio (EN/UH) was 7 and 15 for Anti-Xa activity, 1.3 and 3.1 for Anti-IIa activity after sc injection of EN 40 mg (4,000 Anti-Xa IU and 1,200 Anti-IIa U) and 1 mg kg-1 (7,300 +/- 640 Anti-Xa IU and 2,190 +/- 290 Anti-IIa IU) respectively. In volunteers receiving EN, a dose dependent inhibition of thrombin generation rate in platelet depleted plasma (PDP), measured with a new and simple chromogenic thrombin generation assay, was observed when compared with baseline values. Similarly, intrinsic prothrombin activation in whole blood, evidenced by measuring residual factor II in serum 2 hours after clotting (prothrombin consumption test: PC), was inhibited in a dose dependent manner. In UH treated volunteers, although the inhibition of thrombin generation rate in PDP was similar to that observed with EN 40 mg, prothrombin consumption in whole blood was not significantly modified. Tissue factor pathway inhibitor (TFPI) activity release was increased similarly for UH and EN 40 (1.4 fold increase above baseline values) and 1.9 fold for the higher dose of EN. The discrepancy between prothrombin consumption in whole blood and inhibition of thrombin generation rate in PDP in the UH and not in the EN group strongly suggests that UH and not EN is influenced by the presence of a platelet component. This could be formed during thrombin induced platelet activation. Platelet factor 4 is a possible candidate. Another hypothesis involves the role of TFPI-UH complex anticoagulant activity which might be inhibited more during whole blood coagulation than the TFPI-EN complex.

Adult↗
PubMed1989

Prothrombin time ratio and other factors associated with bleeding in patients treated with warfarin.

We previously showed that the risk of major hemorrhage in patients with venous thromboembolism treated with warfarin was strongly related to duration of anticoagulant therapy. We here report the results of a more detailed analysis of factors other than duration of warfarin therapy associated with the risk of hemorrhage in these patients. Almost 7% of patients had a major hemorrhage on warfarin and an additional 23.7% had at least one minor bleeding episode. Age, female sex, and congestive heart failure were associated with small increases in the risk of major hemorrhage but not with the risk of minor bleeding. A prothrombin time ratio greater than 2.5 was associated with a fourteen-fold increase in the risk of a major hemorrhage (95% CI 5.1, 42.7), but major hemorrhages occurred in patients on warfarin at all measured values of the prothrombin time ratio. Taken together with the findings from our previous analysis, the study suggests that prevention of bleeding in patients on warfarin would best be accomplished by minimizing the duration of warfarin therapy, by scrupulous monitoring of the prothrombin time ratio, and by considering the "therapeutic range" for the prothrombin time ratio to be somewhat less than 2.0-2.5.

Adult↗
PubMed2005

A systematic review of the association between factor V Leiden or prothrombin gene variant and intrauterine growth restriction.

OBJECTIVE: The purpose of this study was to conduct a systematic review of the literature of studies that examined the association between factor V Leiden and/or prothrombin gene variant and intrauterine growth restriction. STUDY DESIGN: This systematic review of studies assesses the association between factor V Leiden and/or prothrombin gene variant and intrauterine growth restriction. RESULTS: Ten case-control studies fulfilled the selection criteria for inclusion in the meta-analysis. There was a significant association between factor V Leiden and intrauterine growth restriction (odds ratio, 2.7; 95% CI, 1.3-5.5) and prothrombin gene variant and intrauterine growth restriction (odds ratio, 2.5; 95% CI, 1.3-5.0). Five cohort studies were identified in the systematic review; 3 studies were prospective (2 full publications), and 2 studies were retrospective (1 full publication). Combining the 2 full publication prospective studies yields a summary relative risk of 0.99 (95% CI, 0.5-1.9). CONCLUSION: This meta-analysis of case-control studies suggests that the factor V Leiden and prothrombin gene variant both confer an increased risk of giving birth to an intrauterine growth restricted infant, although this may be driven by small, poor-quality studies that demonstrated extreme associations. Large well-conducted prospective cohort studies are required to determine definitively whether an association between thrombophilia and intrauterine growth restriction is present.

Case-Control Studies↗
PubMed2006

Association of corticosteroids and factor V, prothrombin, and MTHFR gene mutations with avascular osteonecrosis in renal allograft recipients.

The mechanism of posttransplantation avascular osteonecrosis (AVN) is controversial. Besides an increased bone marrow pressure due to reduced blood supply, enhanced coagulation has been considered. We investigated the associations of factor V Leiden, prothrombin G20210A, and MTHFR C677T mutations as well as cumulative corticosteroid doses with AVN in renal allograft recipients. The records of 39 volunteer patients and 11 patients in whom osteonecrosis was previously identified were reviewed for cumulative corticosteroid dosages during the first year. All patients were screened for factor V Leiden, prothrombin G20210A, and MTHFR C677T mutations by direct sequencing of genomic DNA. The cumulative corticosteroid dosages at 3, 6, and 12 months in the osteonecrotic group (5033.5 +/- 1565.3, 7164.9 +/- 2063.1, 8835.1 +/- 2216.8 mg) were significantly higher than in the control group (3629 +/- 1504.1, 4784.5 +/- 1568.7, 6322.4 +/- 1686.6 mg; P = .013, P = .001, P = .001, respectively). No significant difference in factor V Leiden, prothrombin G20210A, and MTHFR C677T mutations was observed between the osteonecrotic and control groups (P > .05). In conclusion, an association between the first year (3, 6, and 12 month) cumulative corticosteroid dosages and AVN was demonstrated in renal transplant recipients. However, no correlation was determined between factor V Leiden, prothrombin G20210A, and MTHFR C677T mutations and osteonecrosis.

Adrenal Cortex Hormones↗
PubMed1984

Membrane insertion of prothrombin.

The nature of the interaction of prothrombin with liposomes was examined by labelling with the apolar reagent 5-[125I] iodonaphthyl-1-azide (INA). When liposomes containing phosphatidylcholine were incubated with prothrombin and INA, the amount of incorporated label was greater in the absence of added calcium. Increasing the phosphatidylserine content of the liposomes, irrespective of CA++ resulted in a significant increase in the labelling of prothrombin by INA. Since INA is confined to the lipid core of the bilayer, these results strongly suggest that prothrombin binds to liposomes, and penetrates into the lipid bilayer.

Azides↗
PubMed1998

Prevalence of the prothrombin gene variant 20210 G --> A among patients with myocardial infarction.

OBJECTIVE: The aim of this study was to determine the prevalence of the prothrombin variant allele 20210A among survivors of myocardial infarction. BACKGROUND: The prothrombin gene variant has been identified as a novel genetic risk factor for venous thrombosis. However, the risk of developing arterial thrombosis as a result of the presence of this mutated allele is unknown. METHODS: The G-->A transition at position 20210 of the 3'-untranslated region was determined in 220 survivors of myocardial infarction and in 295 individuals from the general population. RESULTS: The prevalence of heterozygotes for the prothrombin mutated allele was 3% among patients with myocardial infarction and 0.7% in the general population (P = 0.03). No age-related difference in the prevalence of the mutated allele was observed. However, for individuals over 45 years old the prevalence among females was higher than among males (5% vs. 0%). CONCLUSION: These data suggest that being heterozygote for the allele variant 20210A of the prothrombin gene could be a genetic risk factor for developing myocardial infarction.

Adult↗
PubMed2001

Accuracy and precision of point-of-care testing for glucose and prothrombin time at the critical care units.

The use of point-of-care testing (POCT) in critical care patient units has continued to increase since the 1980s. This increase is due to the need for prompt therapeutic interventions that may impact mortality and morbidity, and reduce the overall cost of healthcare for critically ill patients. The diagnostic manufacturing industry has risen to this challenge by introducing portable and/or handheld analyzers for use at the point-of-care. In order to ensure the public safety in the USA, the Food and Drug Administration (FDA) must approve the use of each POCT analyzer. The FDA approval is based on established performance criteria that includes relative accuracy and precision documentation. This study evaluated the precision and accuracy of the POCT prothrombin time and glucose analyzers relative to the manufacturers' specifications, to the internal QC in the main laboratory, and to the results of the external proficiency-testing program. The QC for the prothrombin time had a precision that ranged from 2.84% to 3.45% (POCT) and from 1.27-1.66% (main laboratory). The precision for the glucose QC ranged from 5% to 5.2% (POCT) and 0.9-2.7% (main laboratory). Using the results of the external proficiency testing, the inter-laboratory CV% for the POCT prothrombin time ranged from 3.5% to 5.0% and the main laboratory had a range of 2.5-2.9%. The inter-laboratory CV% ranges for glucose POCT and the main laboratory were 4.9-10.6% and 1.8-3.5%, respectively. The main laboratory analyzers proved to be more accurate than the POCT analyzers as indicated by comparison to the mean prothrombin time and glucose results of all participating laboratories in the proficiency testing program.

Blood Glucose↗