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PubMed1985

Precursor prothrombin status in patients receiving anticonvulsant drugs.

Protein induced by vitamin K absence (PIVKA) is the circulating prothrombin precursor found in considerable concentrations when carboxylation of prothrombin is impaired. In this study PIVKA-positivity was assessed in adult epileptic patients receiving a variety of anticonvulsant drugs. Mean PIVKA (+/- SD) concentration was 4.6 +/- 2.3% in 16 epileptics vs 1.1 +/- 0.7% in 10 age-matched controls (p less than 0.001). 13 of the 16 (81%) epileptics had PIVKA values above the highest value recorded for the controls (Fisher exact test, p less than 0.001). Other indices of coagulation were normal. There was no correlation between PIVKA concentration and the particular anticonvulsant taken. This study therefore shows that most epileptics on anticonvulsant therapy have a subclinical coagulation defect. These data, together with previous findings of raised PIVKA concentrations in maternal-infant pairs exposed to gestational anticonvulsants and reports of neonatal haemorrhage in infants of epileptics, strengthen the case for antenatal vitamin K supplementation in pregnancies complicated by anticonvulsant therapy.

Adult↗
PubMed2004

Drotrecogin alfa activated (recombinant human activated protein C) in combination with heparin or melagatran: effects on prothrombin time and activated partial thromboplastin time.

Recombinant human activated protein C (rhAPC) has recently been demonstrated to be a promising candidate to improve the outcome for patients with severe sepsis. Plasma-derived activated protein C and unfractionated heparin (UH) exert anticoagulant synergy due to mechanisms that simultaneously decrease thrombin generation. Melagatran, a new direct thrombin inhibitor, does not bind to plasma proteins or requires antithrombin as a cofactor. The latter is often consumed in patients with severe sepsis. We investigated the anticoagulant efficiency in combined administration of rhAPC and UH or melagatran in terms of prolongation of the standard clotting assays activated partial thromboplastin time (aPTT) and prothrombin time (PT) in pooled plasma samples in vitro. RhAPC dose-dependently prolonged the aPTT but not the PT. The ability of UH and melagatran to prolong the aPTT was significantly enhanced in combination with rhAPC. The combined administration of rhAPC and melagatran, but not UH, resulted in additive prolongation of the PT. In control measurements the capability of rhAPC to suppress prothrombin fragment 1.2 generation dose-dependently increased in combination with heparin and melagatran. Our study demonstrates the respective effects of rhAPC, UH, melagatran and further different additive effects in combined administration of rhAPC and UH or melagatran on the prolongation of the aPTT and PT clotting assays usually used to monitor anticoagulant treatment.

Azetidines↗
PubMed1979

The use of Dispholidus typus venom in elucidating the cause of a low prothrombin index.

A simple and rapid in vitro test was devised to detect the presence of the prothrombin precursor molecule circulating in the plasma of 55 out of 56 patients receiving oral vitamin K antagonists and in 4 out of 5 patients with obstructive jaundice, using either Dispholidus typus or Echis carinatus venoms. The absence of the molecule from the plasma of jaundiced patients was suggestive of hepatocellular rather than obstructive jaundice. The test is based on the clotting of aluminium hydroxide gel adsorbed plasma by the venoms. It is more sensitive and easier to perform than measuring antigenic prothrombin levels.

Adsorption↗
PubMed2006

Traces of factor VIIa modulate thromboplastin sensitivity to factors V, VII, X, and prothrombin.

BACKGROUND: Thromboplastin reagents are used to conduct prothrombin time (PT) clotting tests to monitor oral anticoagulant therapy and screen for clotting factor deficiencies. Thromboplastins made from purified, recombinant tissue factor are generally more sensitive to changes in plasma factor (F) VII levels than are thromboplastins prepared from tissue extracts. This may be problematic as FVII's short plasma half-life can result in day-to-day fluctuation during oral anticoagulant therapy. We hypothesized that trace contamination of tissue-derived thromboplastins with FVII(a) blunts sensitivity to plasma FVII levels. METHODS: Traces of purified FVIIa were added to thromboplastin reagents prepared using recombinant human tissue factor and the effect on sensitivity to individual clotting factors was quantified in PT clotting assays. RESULTS AND CONCLUSIONS: Adding 5-100 pm FVIIa not only decreased thromboplastin sensitivity to plasma FVII, it surprisingly increased sensitivity to plasma levels of FV, FX and prothrombin. In addition, traces of FVIIa interacted with changes in the salt content and phospholipid composition of recombinant thromboplastins to further modulate their sensitivities to individual clotting factors. These results help explain how thromboplastin reagents of differing composition exhibit differing sensitivities to individual clotting factor levels. Implications of our results for monitoring oral anticoagulant therapy and other uses of the PT assay are discussed.

Anticoagulants↗
PubMed1997

Relationship between prothrombin activation fragment F1.2 and international normalized ratio in patients with atrial fibrillation. Stroke Prevention in Atrial Fibrillation Investigators.

BACKGROUND AND PURPOSE: The prothrombin time (expressed as the international normalized ratio [INR]) is the standard method of monitoring warfarin therapy in patients with atrial fibrillation. Prothrombin activation fragment F1.2 provides an index of in vivo thrombin generation and might provide a better index of the effective intensity of anticoagulation. We examined the relationship between F1.2 and INR in patients with atrial fibrillation. METHODS: We measured INR and F1.2 levels in 846 patients with atrial fibrillation participating in the Stroke Prevention in Atrial Fibrillation III study. Two hundred nineteen (26%) were taking aspirin alone, 326 (39%) were taking adjusted-dose warfarin, and 301 (36%) were taking a low fixed dose of warfarin (1 to 3 mg) plus aspirin (combination therapy). F1.2 levels were measured with an enzyme-linked immunosorbent assay. RESULTS: Patients receiving adjusted-dose warfarin or combination therapy had significantly higher INR and significantly lower F1.2 values than those on aspirin alone (P < or = .0001 for each of the four comparisons). F1.2 values (nanomolar) were inversely correlated with INR (F1.2 = -0.1 + 2.3[1/INR]; R2 = .37; P < .0001; simple linear regression). However, significant variability remained. Among patients receiving warfarin, older patients had higher F1.2 values than younger patients after adjustment for INR intensity (P < .001) in the model. There was no difference in the relationship between F1.2 and INR between men and women. CONCLUSIONS: Increasing intensity of anticoagulation, as measured by the INR, is associated with decreasing thrombin generation as measured by the F1.2 level, but significant variability exists in this relationship. Older anticoagulated patients have higher F1.2 values than younger patients at equivalent INR values. The clinical significance of these differences is not clear. F1.2 measurement might provide information regarding anticoagulation intensity in addition to that reflected by the INR.

Aged↗
PubMed1978

Use of prothrombin complex concentrates in hemophiliacs with inhibitors: clinical and laboratory studies.

Nine patients with severe classic hemophilia and inhibitors against factor VIII were treated for 156 bleeding episodes with 503 infusions of Proplex, Konyne, or Auto-Factor IX, three preparations of prothrombin complex concentrates (PCCs). Approximately two thirds of the bleeding episodes were managed successfully. Although the prothrombin time (PT) and partial thromboplastin time (PTT) were shortened after most PCC infusions, there was no evidence of disseminated intravascular coagulation. The degree of shortening of PT or PTT was not related to the particular PCC preparation used, dose, or cessation of hemorrhage. All PCC preparations contained activated clotting factors, as manifested by their ability to shorten the PTT of normal plasma, factor-VIII-deficient plasma, and factor-IX-deficient plasma. Shortening, which was greater with Auto-Factor IX than with the other products, was inhibited partially by a factor IX antibody and blocked completely by prolonged incubation with plasma. Although the nature of the procoagulant material in PCCs is uncertain, these products are of proven benefit to hemophilic patients with high-titer inhibitors. Side effects have been minimal and inhibitor titers have not risen.

Adolescent↗
PubMed1995

[Is the assessment of prothrombin fragment F1+2 for monitoring of heparin therapy in patients with deep vein thrombosis useful?].

Prothrombin fragments (F1+2) can be used to monitor oral anticoagulation; their generation is also suppressed by heparin. We studied the course of F1+2, aPTT, heparin doses administered and heparin concentrations, as well as prothrombin time, during the first 7 days of heparin therapy (target aPTT 70 s) and overlapping oral anticoagulation (target INR 2-3) in 26 patients routinely treated for deep venous thrombosis (deep venous thrombosis +/- pulmonary embolism, 23 patients) or pulmonary embolism with a history of recurring deep venous thrombosis (3 patients). Although we found significant suppression of F1+2 between all pre- and post-treatment values, a transient, significant increase was seen on days 2-4. The amount of heparin given was stable from day 1-5; the fact of a transient increase in F1+2 might thus indicate that heparin doses routinely used are too low for the treatment of hypercoagulability in deep venous thrombosis in patients. We also found a decrease in heparin concentration on day 2, which may be explicable by changed pharmacokinetics of heparin in individuals with deep venous thrombosis. In conclusion, F1+2 may be useful for monitoring heparin treatment and oral anticoagulation in deep venous thrombosis patients from a laboratory point of view. However, larger studies are necessary to confirm these results. It remains to be clarified whether monitoring of anticoagulation by molecular markers might improve therapy of deep venous thrombosis. Such studies are in progress.

Heparin↗
PubMed1993

[Prothrombin fragment 1+2 (F1+2), thrombin-antithrombin III complex(TAT) and thrombophilia parameters in orally anticoagulated patients with inferior vena cava filters].

Prothrombin fragment 1 + 2 (F1 + 2) and thrombin-antithrombin-III-complex (TAT) levels were compared in 31 orally anticoagulated patients with inferior vena caval filters and a control group of 31 orally anticoagulated patients without caval filters and the incidence of markers of thrombophilia (deficiency of antithrombin-III, protein C, protein S and factor XII, presence of lupus anticoagulants) was determined. 8 of 31 patients (26%) from the group of caval filter carriers showed markers of thrombophilia (3 protein S deficiencies, 1 protein C deficiency, 2 factor XII deficiencies and 2 patients with lupus anticoagulants). In all orally anticoagulated patients a significant interdependence (p < 0.05) between F1 + 2- and TAT-levels and intensity (INR) of the oral anticoagulation could be observed. Comparison of F1 + 2- and TAT-levels of caval filter carriers and controls revealed no significant difference which leads to the conclusion that inferior vena caval filters do not induce detectable systemic activation of prothrombin under adequate oral anticoagulation therapy.

Administration, Oral↗
PubMed1995

The use of prothrombin fragment F1+2 to monitor the effect of oral anticoagulation.

In comparison to a control group of 47 healthy, non-anticoagulated persons, 164 patients under stable oral anticoagulation therapy showed significant reduction in the plasma level of the prothrombin fragment F1+2 (p < 0.0005). Even with low intensity anticoagulation (INR < 2.0), F1+2 levels were reduced to within the normal range (0.32 - 1.2 nM/l) in all patients. The reduction in the plasma level of prothrombin fragment F1+2 is directly dependent on the intensity of oral anticoagulation therapy and provides a means of monitoring the anticoagulation effect achieved. Clinical studies are required to assess the practicality of using F1+2 for monitoring anticoagulation and in particular to assess the usefulness of low levels in predicting bleeding risk and high levels in predicting thrombotic risk during treatment.

Administration, Oral↗
PubMed1986

Diagnostic efficacy of six plasma proteins in evaluating consumptive coagulopathies. Use of receiver operating characteristic curves to compare antithrombin III, plasminogen, alpha 2-plasmin inhibitor, fibronectin, prothrombin, and protein C.

Six coagulation proteins were measured in 79 consecutive patients referred to the coagulation service for suspected disseminated intravascular coagulation. Antithrombin III, plasminogen, and alpha 2-plasmin inhibitor were measured with fluorescent substrate assays. Fibronectin, prothrombin, and protein C were measured with electroimmunoassays. Using history and physical findings and the results of a coagulation screen (prothrombin time, partial thromboplastin time, fibrinogen, fibrin[ogen] degradation products, platelet count, and peripheral smear), the 79 patients were classified into five categories: no disseminated intravascular coagulation (n = 21), elevated fibrin(ogen) degradation products without other evidence of coagulopathy (n = 44), defibrination syndrome (n = 9), microangiopathic thrombocytopenic purpura (n = 4), and primary fibrinolysis (n = 1). Because the sensitivity and specificity of each of the proteins could not easily be compared, receiver operating characteristic (ROC) curves and areas under the ROC curves were calculated for each of the six proteins as well as for the tests of the coagulation screen. The ROC curves indicated that, apart from plasminogen, the other coagulation proteins provided little additional information about the classification of the coagulopathy.

Antithrombin III↗
PubMed2004

Prothrombin 20210A mutation: a mild risk factor for venous thromboembolism but not for arterial thrombotic disease and pregnancy-related complications in a family study.

BACKGROUND: The prothrombin 20210A mutation has been associated with an increased risk of venous thromboembolism (VTE). Its relationship with arterial disease and pregnancy-related complications is, however, still uncertain. The aim of this study was to estimate the incidences of first venous and arterial thrombotic events and pregnancy-related complications in relatives of patients with the mutation. METHODS: After clinical classification, the presence of the mutation was determined in first-degree relatives of consecutive patients with the mutation and a history of VTE or premature atherosclerosis. Relatives with and without the mutation were compared. RESULTS: Of all relatives, 204 (50%) were heterozygous, 5 were homozygous, and 198 had a normal genotype. The annual incidence of a first episode of VTE was 0.35% and 0.18% in carriers and noncarriers, respectively (odds ratio [OR], 1.9; 95% confidence interval [CI], 0.9-4.1); the annual incidence of a first arterial thrombosis was 0.22% and 0.15% in carriers and noncarriers, respectively (OR, 2.3; 95% CI, 0.8-6.3). The annual incidence of a first myocardial infarction was 0.14% (95% CI, 0.05%-0.23%) and 0.05% (0.01%-0.14%) in carriers and noncarriers, respectively (OR, 4.7; 95% CI, 1.0-22.5; P =.06). In particular, homozygous carriers were at increased risk of VTE (OR, 6.0; 95% CI, 1.3-27.2), whereas a history of VTE in the proband influenced the risk of VTE in the relatives. Women with the mutation did not experience significantly more pregnancy-related complications than their relatives with a normal genotype. CONCLUSIONS: The prothrombin mutation is a mild risk factor for VTE within families of carriers but does not seem to play an important role in arterial thrombotic disease, with the exception of myocardial infarction, or in pregnancy-related complications.

Adolescent↗
PubMed1998

Prothrombin mutant, factor V Leiden, and thermolabile variant of methylenetetrahydrofolate reductase among patients with sickle cell disease in Brazil.

The prevalence of the prothrombin gene variant (allele 20.210 A), factor V Leiden mutation, and homozygosity for transition 677C-->T in the methylenetetrahydrofolate reductase (MTHFR) gene was determined among patients with sickle cell disease (SCD). The group included 73 patients with median age of 32.3 years with a diagnosis of sickle cell anemia in 53 patients, hemoglobinopathy SC in 16 patients, and four with S/beta(0) thalassemia. Vascular complications such as ischemic stroke or deep vein thrombosis were diagnosed in nine patients. Heterozygosity for the prothrombin gene variant or factor V Leiden mutation was identified in four patients. However, only one patient, who developed ischemic stroke, was identified as a carrier of factor V Leiden mutation. None of the patients presented homozygosity for the thermolabile variant of the MTHFR. These data suggest a low clinical impact of inherited hypercoagulability risk factors in developing thrombosis, occlusive stroke, or mortality data among patients with SCD in Brazil.

Adolescent↗
PubMed2000

Meizothrombin, an intermediate of prothrombin activation, stimulates human glioblastoma cells by interaction with PAR-1-type thrombin receptors.

Thrombin induces well-characterized effects on normal and neoplastic brain cells by interaction with protease-activated receptor (PAR)-type thrombin receptors. However, nothing is known about the function of intermediate enzymes of prothrombin activation recently shown to evoke PAR-1-mediated signaling in smooth muscle cells. Therefore, we investigated the effect of recombinant human meizothrombin (rMT), one of thrombin's catalytically active precursor enzymes in the prothrombin cleavage cascade, on calcium mobilization in human SNB-19 glioblastoma cells. By using reverse-transcription polymerase chain reaction, immunofluorescence studies with a monoclonal anti-PAR-1 antibody and calcium measurements, SNB-19 cells were shown to express functional PAR-1-type thrombin receptors. PAR-1 is not only a receptor for thrombin in SNB-19 cells but was also activated by rMT very effectively. Under the conditions used in our experiments, SNB-19 cells stimulated with thrombin after rMT challenge were unable to elicit a new calcium response and vice versa. In addition, both rMT and thrombin induced no further calcium signal after that observed with the PAR-1-activating peptide SFLLRN. Therefore, rMT and thrombin seem to activate calcium signaling by similar mechanisms including PAR-1. Our results demonstrate rMT as a potent activator of PAR-1-type thrombin receptors in SNB-19 glioblastoma cells, suggesting a function of catalytically active thrombin precursor enzymes in cells of glial origin.

Calcium↗
PubMed2000

Combined heterozygosity of factor V leiden and the G20210A prothrombin gene mutation in a patient with cerebral cortical vein thrombosis.

Cerebral venous thrombosis (CVT) is a rare type of stroke with a variety of causes. Several reports have suggested that either factor V Leiden or G20210A prothrombin gene mutation is associated with an increased risk of CVT. The genetic thrombophilias are typically associated with other predisposing factors. We report a unique case of CVT in a patient with both the factor V Leiden and the G20210A prothrombin gene mutations without other identifiable precipitating factors in a 28-year-old white male in good health. MRI and cerebral arterial angiography showed cerebral cortical venous thrombosis. This case suggests that combined heterozygous individuals may be particularly prone to spontaneous thrombosis, like CVT.

Adult↗
PubMed2001

Des-gamma-carboxy prothrombin as a useful predisposing factor for the development of portal venous invasion in patients with hepatocellular carcinoma: a prospective analysis of 227 patients.

BACKGROUND: Portal venous invasion (PVI) in patients with hepatocellular carcinoma (HCC) is an important factor affecting prognosis. The objective of this study was to elucidate predisposing factors for the development of PVI. METHODS: Two hundred twenty-seven patients with HCC who did not show PVI and who received percutaneous ethanol injection therapy and/or microwave coagulation therapy at the time of their first hospital admission were enrolled between 1994 and 1996. After their HCC was treated, the patients were followed for a mean of 19 months. For the detection of HCC recurrence and/or development of PVI, ultrasonography was performed every 3 months, a computed tomography (CT) scan was performed every 6 months, and the biochemical parameters of the patients were measured every month. PVI was defined as protrusion of the tumor into the first and/or second branch or into the main trunk of the portal vein. RESULTS: Of the 227 patients, 24 (11%) later developed PVI. Tabular analysis was performed on these 24 patients and indicated that tumor size, albumin, total bilirubin, prothrombin time, alpha-fetoprotein (AFP) level, and des-gamma-carboxy prothrombin (DCP) level differed significantly between the time of initial admission and the time of PVI development. A univariate analysis performed on the 227 patients indicated that an increase in the numbers of tumors, the histologic tumor grade (differentiation), the AFP level, and the DCP level at the time of initial diagnosis of HCC had a significant correlation with the later development of PVI; and a stepwise, multivariate Cox regression analysis revealed that the DCP level was the strongest predisposing factor (P < 0.0010; risk ratio = 5.65) followed by the histologic grade of tumor differentiation. CONCLUSIONS: The results suggest that the serum DCP level is the most useful predisposing clinical parameter for the development of PVI.

Adult↗
PubMed2003

Factor V Leiden and prothrombin gene G20210A mutation in children with cerebral thromboembolism.

We investigated whether there is an association between factor V Leiden (FVL) and/or prothrombin gene G20210A mutation (PT20210A) and cerebral thromboembolism in a pediatric Argentinean population. From May 1992 to January 2002, 44 consecutive children with arterial ischemic stroke (AIS) and 23 children with cerebral sinovenous thrombosis (SVT) were prospectively studied at a single center. The prevalence of both mutations was compared with a 102 age-matched controls. In children with AIS, the frequencies (patients vs. controls), odds ratio (OR), and 95% confidence interval (95% CI) for the presence of FVL were as follows: 2.3% vs. 2%, OR/95% CI, 1.16/0.2 to 13.2; P value = 0.99. No cases of PT20210A were found in this group. In children with SVT, the frequencies (patients vs. controls), OR, and 95% CI were as follows: FVL (4.3% vs. 2%, OR/95% CI, 2.27/0.22 to 6.2; P value = 0.99) and PT20210A (4.3% vs. 1%; OR/95% CI, 4.6/0.3 to 76.3; P value = 0.3354). One child with PT20210A also had an inherited protein C deficiency. In 12 (18%) out of the 67 children with cerebral thromboembolism, without the aforementioned mutations, other prothrombotic disorders were detected. Although a multi-center prospective study with a large number of Argentinean pediatric patients is needed to obtain considerable evidence, no association between factor V Leiden and/or prothrombin gene G20210A mutation and cerebral thromboembolism was found in this pediatric series.

Adolescent↗
PubMed1987

Evaluation of the nature of mildly prolonged prothrombin times.

Twenty-one asymptomatic individuals with a mildly prolonged prothrombin time (greater than 2 SD from the prothrombin time of the reference plasma) were found to have a mild isolated factor VII (F VII) defect (mean 38.8 U/dl; SD 13.2). Factor VII antigen levels were also found to be reduced (mean 45.5 U/dl; SD 7.8) in 13 of them. These figures were compared with those of 50 normals and 28 obligatory heterozygotes for F VII deficiency. The phenotypical behaviors in the propositi were found to be equal to those of the F VII congenital deficiency heterozygotes: the discrepant one (VII+) and the nondiscrepant one (VII-/R). Fifteen families of the propositi could also be studied, totalling 55 additional individuals; in 25 of them (ten pedigrees) a mild F VII deficiency was found showing the same phenotypical features of the corresponding propositi. We therefore believe that these individuals with mild F VII deficiency can be considered as heterozygotes for the defect, since the other vitamin K-dependent clotting factors were normal; the defect is transmitted throughout the kindred with the same mode of inheritance as F VII congenital deficiency; and F VII:C and F VII:Ag levels are highly comparable with those of known obligatory heterozygotes for F VII deficiency. On the grounds of a careful statistical analysis we propose a formula which allows a discrimination between the two phenotypes of the heterozygotes for F VII congenital deficiency. In addition it is suggested that sensitive tissue thromboplastins should be used to pick up these mild defects.

Adolescent↗
PubMed2006

Renal prothrombin mRNA is significantly decreased in a hyperoxaluric rat model of nephrolithiasis.

Although urinary prothrombin fragment 1 (UPTF1) possesses several hallmarks expected of a regulatory protein in urolithiasis, its precise role remains unknown. To determine the relationship between renal prothrombin (PT), the parent molecule of UPTF1, and lithogenesis, this study quantified and compared levels of renal PT mRNA in healthy rats (n = 10) and rats rendered lithogenic (n = 10) by ingestion of 0.75% ethylene glycol for 8 weeks. Studies included morphological and histological examination of the kidneys with scanning electron microscopy of the urinary filtrates of control and experimental animals. Haematuria and calcium oxalate (CaOx) crystals occurred in the urine of all experimental rats, but not in those of controls. Histological examination showed birefringent nephroliths and associated damage in kidneys of lithogenic rats, which were not seen in the control group. The amounts of total RNA extracted from both groups of rats were similar, but the median ratio of PT to beta-actin transcript of 11.14 x 10(-4) (10.65 x 10(-4) +/- 2.24 x 10(-4)) in the control rats was significantly (p < or = 0.001) reduced to 6.47 x 10(-4) (6.57 x 10(-4) +/- 2.72 x 10(-4)) in the lithogenic group. These results demonstrate that renal PT mRNA is reduced by approximately 42% in lithogenic rats and confirm the existence of a direct association between renal PT synthesis and calculogenesis. Attempts to compare renal PT and urinary levels of PTF1 were unsuccessful because of interference from hepatic PT circulating in the blood, haematuria, and the presence of urinary CaOx crystals. This is the first report of a significant reduction in the renal expression of a urinary protein well documented to inhibit CaOx crystal growth and aggregation in undiluted human urine in vitro.

Actins↗