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 811 records · Page 45Linked to original sources
PubMed1984

Enhanced prothrombin-converting activity and factor Xa binding of platelets activated by the alternative complement pathway.

Platelet prothrombin-converting activity and factor Xa binding were studied after exposure of human platelet rich plasma (PRP) to various conditions leading to platelet activation. Zymosan resulted in increased platelet-bound C3, enhanced prothrombin-converting activity and increased factor Xa binding. Similar findings were observed with normal platelets resuspended in factor XII-deficient plasma. The combined use of zymosan and thrombin to activate platelets resulted in synergistic prothrombin-converting activity and factor Xa binding. In contrast, no synergism was obtained with the concomitant use of zymosan and collagen, suggesting that collagen and zymosan share the same pathway for platelet activation. Heterologous antibody to factor V completely inhibited the platelet prothrombin-converting activity for all modes of platelet activation, indicating that this activity is mediated by factor V.

Blood Platelets↗
PubMed2005

Anti-prothrombin IgG from patients with anti-phospholipid antibodies inhibits the inactivation of factor Va by activated protein C.

Interference of anti-phospholipid antibodies with the protein C pathway has been suggested to play a role in the development of thrombosis in the anti-phospholipid syndrome. We studied the effect of IgG preparations containing anti-prothrombin antibodies of 17 lupus anticoagulant-positive patients and 12 controls on the inactivation of factor Va (FVa) by activated protein C (APC) in a system with purified coagulation factors. Test IgG was incubated with human prothrombin, phospholipid vesicles and CaCl(2). Protein S, FVa and APC were added and the APC-dependent loss of FVa activity was monitored over time. The residual amount of FVa remaining after 10 min was 14 +/- 4% (mean +/- SD) when 1.5 mg/ml normal IgG was present and ranged between 17% and 82% with 1.5 mg/ml patient IgG. Twelve patients IgG gave values of residual FVa >22% (i.e. 2 SD above the mean of controls), indicating that APC-mediated inactivation of FVa was significantly inhibited. The inhibition was strictly dependent on the presence of prothrombin, proportional to the concentration of IgG and strongly diminished at a 20-fold higher phospholipid concentration. Most, although not all, IgG containing anti-prothrombin antibodies inhibit the APC-catalysed FVa inactivation, which may contribute to the increased risk of thrombosis in patients with the anti-phospholipid syndrome.

Antibodies, Antiphospholipid↗
PubMed1978

Turnover of radiolabelled plasminogen and prothrombin in cirrhosis of the liver.

The turnover of purified radiolabelled plasminogen was studied in four patients with cirrhosis of the liver, and that of radiolabelled prothrombin in six patients with cirrhosis of the liver. The cirrhotic patients showed an increased fractional catabolic rate and a decreased synthetic rate, resulting in subnormal plasma levels of plasminogen and prothrombin. The plasma concentration of the two proteins correlated with the synthetic rate, but not with the fractional catabolic rate. Heparin infusion prolonged the shortened half-life of plasminogen in two cirrhotics from 1.25 to 2.10 days and from 1.45 to 1.90 days, and the half-life of prothrombin in three cirrhotics from 2.25 to 2.70 days, from 2.35 to 2.80 days and from 2.40 to 3.70 days. These results indicate that the abnormal turnover of labelled plasminogen and prothrombin in cirrhosis of the liver is due to two mechanisms; increased breakdown, reversible by heparin administration, and impaired synthesis. The decreased plasma levels are, however, mainly caused by decreased synthesis.

Humans↗
PubMed1992

Inhibition of factor X, factor V and prothrombin activation by the bis(lactobionic acid amide) LW10082.

The minimum concentrations of heparin, dermatan sulfate, hirudin, and D-Phe-Pro-ArgCH2Cl required to delay the onset of prothrombin activation in contact-activated plasma also prolong the lag phases associated with both factor X and factor V activation. Heparin and dermatan sulfate prolong the lag phases associated with the activation of the three proteins by catalyzing the inhibition of endogenously generated thrombin. Thrombin usually activates factor V and factor VIII during coagulation. The smallest fragment of heparin able to catalyze thrombin inhibition by antithrombin III is an octadecasaccharide with high affinity for antithrombin III. In contrast, a dermatan sulfate hexasaccharide with high affinity for heparin cofactor II can catalyze thrombin inhibition by heparin cofactor II. A highly sulfated bis(lactobionic acid amide), LW10082 (Mr 2288), which catalyzes thrombin inhibition by heparin cofactor II and has both antithrombotic and anticoagulant activities, has been synthesized. In this study, we determined how the minimum concentration of LW10082 required to delay the onset of intrinsic prothrombin activation achieved this effect. We demonstrate that, like heparin and dermatan sulfate, LW10082 delays the onset of intrinsic prothrombin activation by prolonging the lag phase associated with both factor X and factor V activation. In addition, LW10082 is approximately 25% as effective as heparin and 10 times as effective as dermatan sulfate in its ability to delay the onset of prothrombin activation. The strong anticoagulant action of LW10082 is consistent with previous reports which show that the degree of sulfation is an important parameter for the catalytic effectiveness of sulfated polysaccharides on thrombin inhibition.

Antithrombin III↗
PubMed2006

Molecular evolution caught in action: gene duplication and evolution of molecular isoforms of prothrombin activators in Pseudonaja textilis (brown snake).

BACKGROUND: The evolution of structurally and functionally similar proteins with highly diverse physiological roles within a single organism is of great interest. Australian elapid snakes offer an excellent opportunity to study the molecular evolution of prothrombin activators. Venom from Pseudonaja textilis contains pseutarin C, a group C prothrombin activator. Its enzymatic subunit is structurally and functionally similar to mammalian factor (F) Xa, whereas its non-enzymatic subunit is similar to FVa. As vertebrates, the snakes also contain a system to activate prothrombin in their own blood during injury. These hemostatic factors are produced in the liver. RESULTS: Here we describe the presence of two molecular forms of FX expressed in the liver of P. textilis. Both isoforms have molecular signatures and domain architecture of FX. However, one isoform shows approximately 94% sequence identity with the snake FX from Tropidechis carinatus, whereas the other is much closer (90% identity) to the catalytic subunit of pseutarin C (PCCS). Real-time polymerase chain reaction reveals that the latter isoform is expressed approximately 56 000 times lower in the liver of P. textilis. However, the isoforms are not expressed in the venom gland. CONCLUSION: A detailed analysis of deletions and insertions along with the sequence indicates that the second isoform is an intermediate caught in the evolution of venom prothrombin activator from the blood coagulation FX. Thus, this isoform represents a 'molecular fossil' and reveals the likely evolutionary path of recruitment of FX in the venom gland.

Amino Acid Sequence↗
PubMedDate not supplied

G20210A prothrombin gene mutation identified in patients with venous leg ulcers.

The G20210A mutation variant of prothrombin gene is the second most frequent mutation identified in patients with deep venous thrombosis, after factor V Leiden. The risk for developing deep venous thrombosis is high in patients identified as heterozygous for G20210A mutation. In order to identify this polymorphism in the gene coding prothrombin, the 345bp fragment in the 3'- untranslated region of the prothrombin gene was amplified using amplification by polymerase chain reaction and enzymatic digestion by HindIII (restriction endonuclease enzyme). The products of amplification and enzymatic's digestion were analized using agarose gel electrophoresis. We investigated 20 patients with venous leg ulcers and we found 2 heterozygous (10%) for G20210A mutation. None of the patients in the control group had G20210A mutation. Our study confirms the presence of G20210A mutation in the Romanian population. Our study also shows the link between venous leg ulcers and this polymorphism in the prothrombin gene.

Aged↗
PubMed2006

Expression of prothrombin, thrombin and its receptors in human scars.

The coagulation system is thought to play a pivotal role during the initial phase of wound healing, but mechanisms and cells involved are only partly understood. We have therefore examined human scars for the expression of thrombin, its precursor prothrombin and the thrombin receptors, thrombomodulin (TM) and protease-activated receptor-1 (PAR-1), compared with normal skin. Biopsies of scars were obtained from primary excision sites of melanoma patients (n = 20) and were compared with normal skin distant from the scar (n = 10), using immunohistochemistry. In addition, polymerase chain reaction analyses were performed on scar versus normal tissue and on cultured keratinocytes, fibroblasts and endothelial cells before and after stimulation with selected cytokines known to be active in wound healing. Normal epidermis was stained for prothrombin, thrombin, TM and PAR-1, and dermal tissue was stained only for TM and PAR-1. In scar tissue, thrombin and TM were upregulated in the epidermis and all four molecules in the dermis, independent of the age of the scars. In tissue extracts, mRNA expression of PAR-1 and prothrombin expression were, however, unchanged and TM even slightly decreased in scars, compared with normal skin. On analysis of cultured cells, keratinocytes expressed mRNA for PAR-1, TM and prothrombin, endothelial cells for PAR-1 and TM, and fibroblasts for PAR-1. An upregulation of PAR-1 mRNA was induced in fibroblasts on exposure to tumor necrosis factor-alpha (TNF-alpha), while it remained unchanged in endothelial cells in response to TNF-alpha. A downregulation of TM was induced in endothelial cells on exposure to TNF-alpha. These findings, showing a marked modulation of thrombin, PAR-1 and TM even in older human scar tissue, suggest that the coagulation system is not only involved during clotting, but also during the inflammatory and tissue remodelling phases of wound healing.

Cells, Cultured↗
PubMed2006

Sialylation of urinary prothrombin fragment 1 is implicated as a contributory factor in the risk of calcium oxalate kidney stone formation.

Urinary glycoproteins are important inhibitors of calcium oxalate crystallization and adhesion of crystals to renal cells, both of which are key mechanisms in kidney stone formation. This has been attributed to glycosylation of the proteins. In South Africa, the black population rarely form stones (incidence < 1%) compared with the white population (incidence 12-15%). A previous study involving urinary prothrombin fragment 1 from both populations demonstrated superior inhibitory activity associated with the protein from the black group. In the present study, we compared N-linked and O-linked oligosaccharides released from urinary prothrombin fragment 1 isolated from the urine of healthy and stone-forming subjects in both populations to elucidate the relationship between glycosylation and calcium oxalate stone pathogenesis. The O-glycans of both control groups and the N-glycans of the black control samples were significantly more sialylated than those of the white stone-formers. This demonstrates a possible association between low-percentage sialylation and kidney stone disease and provides a potential diagnostic method for a predisposition to kidney stones that could lead to the implementation of a preventative regimen. These results indicate that sialylated glycoforms of urinary prothrombin fragment 1 afford protection against calcium oxalate stone formation, possibly by coating the surface of calcium oxalate crystals. This provides a rationale for the established roles of urinary prothrombin fragment 1, namely reducing the potential for crystal aggregation and inhibiting crystal-cell adhesion by masking the interaction of the calcium ions on the crystal surface with the renal cell surface along the nephron.

Adult↗
PubMedDate not supplied

Interaction of bothrojaracin with prothrombin.

Bothrojaracin (BJC) is a 27-kD protein from Bothrops jararaca venom that interacts with alpha-thrombin (K(D) = 0.7 nM) through both anion-binding exosites I and II. Recently, it has been shown that BJC interacts with the exosite I precursor (proexosite I) on human prothrombin (K(D) = 75 nM), forming a 1:1 Ca(2+)-independent noncovalent complex with the zymogen. Complex formation was associated with inhibition of zymogen activation by Oxyuranus scutellatus venom. In addition, BJC strongly decreased the prothrombin activation by factor Xa only in the presence of factor Va. A similar effect was observed in the presence of phospholipids, suggesting that BJC specifically inhibits the interaction of prothrombin with factor Va. It is proposed that BJC has two independent mechanisms for anticoagulation: (1) inhibition of exosite-I-dependent activities on alpha-thrombin, and (2) inhibition of prothrombin activation through interaction with proexosite I.

Animals↗
PubMed1990

Tumor cells augment the factor Xa-catalyzed conversion of prothrombin to thrombin.

Activation of blood coagulation and local fibrin deposition may contribute to tumor metastasis. We have examined the ability of four human tumor cell lines (COLO 205, HepG2, J82 and CAPAN-2) to augment the conversion of prothrombin to thrombin by factor Xa and calcium in the presence and absence of exogenous factor Va. Using a chromogenic substrate assay to assess thrombin formation, we observed that all the above cell lines accelerated prothrombin activation in the absence of exogenous factor Va. The order of effectiveness was COLO 205 greater than HepG2 greater than J82 greater than CAPAN-2. In the absence of cells, no detectable thrombin formation occurred. Pretreatment of COLO 205 and HepG2 cells with anti-human factor V IgG inhibited prothrombin activation in a dose-dependent manner, but was without effect in J82 and CAPAN-2 incubation mixtures. Factor V coagulant activity was observed in COLO 205 and HepG2 cells as well as their culture media, but was not detected in J82 and CAPAN-2 cells or their culture media. Biosynthetic labeling and immunoprecipitation studies revealed that COLO 205 and HepG2 cells constitutively synthesized factor V or a factor-V-like molecule that comigrated with human factor V/Va on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. All four tumor cell lines exhibited saturation binding of exogenous human factor Va resulting in a dose-dependent enhancement of their ability to augment prothrombin activation. Our results indicate that these tumor cells can readily assemble a functional cell surface prothrombinase complex that may be important in fibrin deposition associated with the growth and metastatic progression of these, and perhaps, other tumors.

Enzyme Activation↗
PubMed1998

Clinical studies and thrombin generation in patients homozygous or heterozygous for the G20210A mutation in the prothrombin gene.

A genetic variation in the prothrombin gene, the G-->A transition at nucleotide 20210, is a risk factor for venous thrombosis in heterozygotes and is associated with increased prothrombin activity. The homozygous phenotype and the extent of thrombin generation in heterozygous and homozygous subjects are unknown. We investigated a family that included 2 homozygous and 5 heterozygous carriers of the 20210 A allele. The homozygous propositus and his presumably heterozygous father suffered from deep-vein thrombosis. His presumably heterozygous mother and his homozygous sister had recurrent phlebitis at a young age. The remaining 5 affected family members are still asymptomatic. We studied thrombin generation in the family and in 22 unrelated carriers of the 20210 A allele by measuring (1) prothrombin fragment F1+2 (F1+2) as an index of ongoing thrombin generation and (2) the endogenous thrombin potential (ETP) as an index of the possible thrombin-forming capacity. Their F1+2 levels were not different from those of age-matched controls, and thus, ongoing hemostatic system activation was not detectable. A significantly increased ETP was found in the heterozygous carriers of the 20210A allele compared with the controls (527.8+/-114.9 versus 387+/-50.1 nmol/L x min, P<0.0001). In the 2 homozygotes, the ETP was almost twice (639 and 751 nmol/L x min, respectively) as high as in the controls. We conclude that homozygosity for the G20210A mutation in the prothrombin gene is associated with a severe, albeit more benign, thrombotic diathesis compared with homozygosity for deficiencies of antithrombin, protein C, or protein S. In carriers of the 20210 A allele, the pathomechanisms leading to thrombosis should be sought in the higher amounts of thrombin that may be formed once thrombin generation is triggered, rather than in ongoing thrombin generation in vivo.

Adult↗
PubMed1999

Coagulation factors II, V, VII, and X, prothrombin gene 20210G-->A transition, and factor V Leiden in coronary artery disease: high factor V clotting activity is an independent risk factor for myocardial infarction.

Increased levels of hemostatic factors and genetic mutations of proteins involved in coagulation may play a role in the pathogenesis of coronary artery disease. We investigated clotting activity of factors II (FII:C), V (FV:C), VII (FVII:C), and X (FX:C), the prothrombin gene 20210G-->A transition, and the factor V Leiden mutation in 200 survivors of myocardial infarction and in 100 healthy controls. FV:C (P<0.0001) and FVII:C (P<0.0001) were found to be independent risk factors for myocardial infarction. High FV:C or high FVII:C combined with smoking or arterial hypertension increased the relative risk for myocardial infarction up to 50-fold. One of 177 patients (0.6%) and 4 of 89 controls (4.5%) had the prothrombin 20210 AG genotype. Eleven of 177 patients (6.2%) and 6 of 89 controls (6.7%) were heterozygous for the factor V Leiden mutation. No homozygous carrier for these mutations was found. Neither the prothrombin gene 20210G-->A transition (odds ratio [OR], 0.1; 95% confidence interval [CI], 0.01 to 1.1) nor the factor V Leiden mutation (OR, 1.0; 95% CI, 0.4 to 2.8) were associated with an increased relative risk for myocardial infarction. In conclusion, our data indicate that neither the prothrombin gene 20210G-->A transition nor the factor V Leiden mutation are risk factors for myocardial infarction. High FVII:C was confirmed to be an independent risk factor for myocardial infarction. Moreover, we describe for the first time that high FV:C is an independent risk factor for myocardial infarction.

Activated Protein C Resistance↗
PubMed1998

Frequency of the 20210 G-->A mutation in the 3'-untranslated region of the prothrombin gene in 35 cases of cerebral venous thrombosis.

BACKGROUND AND PURPOSE: A novel sequence variation in the 3'-untranslated region of the prothrombin (factor II) gene (nucleotide 20210 G-->A) has been recently described as a risk factor for deep vein thrombosis and pulmonary embolism. It is found in approximately 1% to 4% of healthy subjects. We studied the frequency of this factor II variant in patients with cerebral venous thrombosis. METHODS: The 20210A allele of the prothrombin gene was studied after DNA extraction, polymerase chain reaction amplification, and HindIII digestion in 35 patients with magnetic resonance imaging or angiographically confirmed cerebral venous thrombosis (23 women and 12 men, aged 11 to 71 years). RESULTS: Two patients (5.7%) had the 20210A allele of the prothrombin gene. Both had other risk factors for thrombosis (use of oral contraceptives and of intrathecal steroids). CONCLUSIONS: The 20210A allele of the prothrombin gene in association with other prothrombic factors may increase the risk of cerebral venous thrombosis, but case-control studies will be necessary to clarify these associations.

Adolescent↗
PubMed2026

Prothrombin G20210A and Factor V Leiden Variants Are Not Associated With Thrombotic Events in Congenital Heart Disease: An Observational Trial.

BACKGROUND: Thrombotic events, including acute ischemic stroke, are more common in individuals with congenital heart disease (CHD). Whether common thrombophilia variants contribute to thrombotic risk in this population remains unclear. We evaluated whether prothrombin G20210A (F2 c.97G>A) and factor V Leiden (F5 c.1601G>A; p.Arg534Gln) are associated with thrombotic events in CHD. METHODS: Participants in the Pediatric Cardiac Genomics Consortium with exome sequencing and electronic medical record data were identified. Individuals were stratified by prothrombin G20210A and factor V Leiden genotypes, ventricular physiology, and antithrombotic therapy. The primary outcome was the presence of International Classification of Diseases (ICD) or Phecodes (phenotype codes) for thrombotic events. RESULTS: Among 4008 participants (median age, 11.4 [interquartile range, 5.1-17.9] years; 44.4% boys), thrombotic events occurred in 737 (18%), including 93 (13%) with acute ischemic stroke. Compared with the Genome Aggregation Database, the CHD cohort had a lower prevalence of heterozygous prothrombin G20210A and factor V Leiden variants. Variant prevalence did not differ between participants with and without thrombotic events. Single-ventricle CHD was associated with higher thrombosis frequency than biventricular CHD (35% versus 16%, P&#x2264;0.0001), without differences in variant prevalence. CONCLUSIONS: In this multicenter CHD cohort, prothrombin G20210A and factor V Leiden were not significantly associated with thrombotic outcomes, supporting recommendations against routine screening. Given low variant prevalence, the study was powered to exclude only large associations. Reduced variant frequency suggests survivorship bias beginning in fetal life. Larger integrated clinical-genomic studies are needed to refine thrombotic risk stratification in CHD. REGISTRATION: URL: https://www.clinicaltrials.gov; Unique Identifier: NCT03347214.

Humans↗
PubMed1986

Inhibition by human thrombomodulin of factor Xa-mediated cleavage of prothrombin.

Human thrombomodulin significantly inhibited the rate of prothrombin conversion to thrombin by Factor Xa in the presence of phospholipid or platelets, calcium, and Factor Va. Sodium dodecyl sulfate polyacrylamide gel electrophoresis of 125I-prothrombin activation revealed that thrombomodulin reduced the rate of prothrombin activation but did not alter the cleavage pattern. The inhibition was reversed by the inclusion of a highly specific rabbit antithrombomodulin antibody. If thrombomodulin was replaced by hirudin, the rate of thrombin generation was not decreased excluding the possibility that the inhibition by thrombomodulin was secondary to the binding of small amounts of thrombin formed early in the reaction and the prevention of feedback breakdown of prothrombin by thrombin. The inhibitory activity of thrombomodulin was overcome by increasing the concentration of Factor Xa and specific, saturable binding of thrombomodulin to Factor Xa was demonstrated. These results indicate that thrombomodulin binds to Factor Xa and thereby inhibits the activity of the prothrombinase complex.

Animals↗
PubMed2000

Combined genetic defect (homogeneity for factor V Leiden and heterogeneity for prothrombin G20210A allele), in a young patient, with recurrent deep vein thrombosis and serious postphlebitic syndrome--a case report.

Just a few years ago, resistance to activated protein C (APCR) was reported to be of high significance representing a strong predisposing factor in the development of venous thrombosis (VT). A little while later, APCR was established to be the result of a point mutation of the factor V gene (factor V Leiden: a G-to-A transition at position 1691). Up to today, it is not certain whether factor V Leiden is in itself able to lead to VT, or whether it acts in synergy with other factors. Nevertheless, heterozygous subjects have a tenfold increase in the risk of VT when compared to general population, whereas the risk is 80 times greater in homozygous individuals. In 1996, a prothrombin gene mutation (prothrombin G20210A allele), which is a single-nucleotide G-to-A transition at position 20210 in the sequence of the 3'-untranslated region (3'UTR) on chromosome 11, was discovered. The presence of this mutant gene results in elevated plasma prothrombin concentrations, increasing the possibility for the development of VT. However, the coexistence of these two abnormalities, as well as the clinical consequence, have not yet been studied. So far, only a few reports are found in the literature describing the coexistence of both mutations. The authors present a 25-year-old patient with a simultaneous double mutation of the FV and F II gene. The patient was homozygous for the factor V Leiden and heterozygous for the prothrombin G20210A allele. It is unclear whether the coexistence of the two predisposes more to the development of VT than the summation of the two as independent factors.

Adult↗
PubMed1999

Asymptomatic homozygous nt 20210 G to A prothrombin polymorphism in two blood donors belonging to two different kindreds.

The nucleotide (nt) 20210 G to A prothrombin polymorphism has been associated with an increased incidence of thrombosis, particularly venous thrombosis. The increased incidence of thrombosis resulted from an increase in prothrombin levels. Two homozygous patients with this abnormality were found to be completely asymptomatic. In one of the two cases there was no thrombosis even after the additional risk factor of oral contraceptive therapy for several months. Prothrombin activity and antigen as assayed by several methods were at the upper limits of normalcy in one case and slightly elevated in the other. The two cases described in this article do not rule out the possibility that this prothrombin abnormality be associated, given special acquired circumstances, with thrombosis. However, they indicate that extreme caution is needed to avoid an inaccurate conclusion. The fact that homozygous patients may remain asymptomatic indicates that the prothrombotic defect is very mild, if any.

Adult↗
PubMed2003

Prothrombin time prolongation in paracetamol poisoning: a relevant marker of hepatic failure?

The association between paracetamol overdose and prolonged prothrombin time due to hepatic failure is well recognized. However, little is known of the possibility that paracetamol overdose can prolong the prothrombin time without overt hepatic failure. The few data from the literature suggest this is either due to a reduction in the functional levels of the vitamin K-dependent clotting factors by elevated doses of paracetamol, or a consequence of the administration of the antidote N-acetylcystein. The three reported cases provide further evidence that paracetamol overdose can be associated with a prolongation in the prothrombin time without overt hepatic failure. Even though the prothrombin time provides useful prognosis information, decisions regarding the management of these patients should not solely be based on this endpoint to avoid misinterpretation of the accuracy and the severity of liver failure.

Acetaminophen↗