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PubMed1998

A dimeric form of prothrombin on membrane surfaces.

Blood coagulation requires the conversion of zymogens to active enzymes. These reactions are facilitated by Ca2+-dependent protein binding to membrane surfaces containing anionic phospholipids. Here it is shown that only in the presence of both Ca2+ and phospholipid vesicles composed of phosphatidylcholine and phosphatidylserine can a prothrombin dimer be chemically cross-linked. A cross-linker containing evenly spaced reactive groups was prepared by activating the carboxy groups of a ten-residue glutamic acid peptide and allowed to react with physiological concentrations of prothrombin. When Ca2+ and anionic phospholipids were both present during exposure to the cross-linker, it was found that more than 50% of the prothrombin was trapped as a chemically defined dimer with reaction times of the order of 1 min. The dimer yield remained high even when reactions were performed at high phospholipid-to-protein ratios at protein concentrations an order of magnitude less than physiological. Amino acid sequencing of a CNBr peptide produced from the purified dimer localized the cross-link to residues Lys341 and Lys427 of prothrombin. The specificity and high yield under mild conditions of the cross-linking suggest that dimeric membrane bound prothrombin might be a physiologically relevant substrate for the formation of thrombin. Prothrombinase converts this modified protein to an enzyme that catalyses the hydrolysis of a thrombin chromogenic substrate as efficiently as thrombin and is inhibited by a thrombin active-site directed inhibitor, but is a thrombin dimer. The thrombin dimer has impaired activity compared with thrombin with respect to physiological functions requiring binding to exosite I. A model based on the known structure of thrombin is presented that can account for the prothrombin dimer and the properties of the dimeric thrombin formed from it.

Animals↗
PubMed2003

Voriconazole potentiates warfarin-induced prothrombin time prolongation.

AIMS: Voriconazole is a novel triazole with broad-spectrum antifungal activity. It is likely that some patients receiving voriconazole may also require treatment with the anticoagulant warfarin. Cytochrome P450 isoenzymes are important in the metabolism of both these drugs. This study investigated the effect of voriconazole on the pharmacodynamics of warfarin by measuring prothrombin time, and also evaluated the safety and tolerability of the coadministered drugs. METHODS: This was a double-blind, placebo-controlled, two-way crossover study in which healthy male subjects received either 300 mg voriconazole or placebo twice daily on days 1-12, plus a single oral dose of 30 mg warfarin on day 7 of each study period. Volunteers were randomized to one of the following treatment sequences: voriconazole + warfarin followed by placebo + warfarin or placebo + warfarin followed by voriconazole + warfarin. There was a washout of at least of 7 days between treatment periods. RESULTS: The mean Cmax, AUCtau and tmax for voriconazole were 3736 ng ml-1, 25 733 ng.h ml-1, and 1.66 h, respectively. Both the mean maximum change from baseline prothrombin time and the mean area under the effect curve (AUEC) for prothrombin time during coadministration with voriconazole (17 s and 3211 s.h, respectively) were statistically significantly greater than the mean values observed during the placebo period (8 s and 2282 s.h ). Prothrombin times were still increased by a mean value of 5.4 s 144 h post warfarin dose following coadministration with voriconazole compared with a mean value of 0.6 s in the placebo treatment period. CONCLUSIONS: Coadministration of voriconazole and warfarin potentiates warfarin-induced prothrombin time prolongation. Regular monitoring of prothrombin time is recommended if these drugs are coadministered, with appropriate adjustment of the dose of warfarin.

Administration, Oral↗
PubMed1999

Binding properties of antibodies to prothrombin and beta2-glycoprotein I (beta2-GPI) assayed by ELISA and dot blot.

Most anti-phospholipid antibodies (aPL) associated with the anti-phospholipid syndrome are autoantibodies with specificity towards beta2-GPI (anti-beta2-GPI) or prothrombin (anti-II). They are mainly screened by ELISA using polyoxygenated plates. However, some authors have claimed that immunoblotting can also be used. Exposure of cryptic epitopes or increase of antigen density on its binding to either phospholipids or suitable plastic surfaces are the two hypotheses proposed for the interaction of beta2-GPI or prothrombin with their antibodies. Forty-five patients with aPL were studied: 25 with lupus anti-coagulant (LA) and anti-cardiolipin antibodies (aCL), 10 with LA alone and 10 with aCL but negative LA. All patients with LA and aCL were positive for anti-beta2-GPI by ELISA and dot blot, while 15/25 had anti-IIELISA and 14 of them also had anti-II by dot blot assay. No patient with LA alone tested positive for anti-beta2-GPI by ELISA or dot blot, whereas 6/10 had anti-IIELISA (five of them were also positive by dot blot). Four out of 10 aCL-positive patients had anti-beta2-GPI by ELISA and dot blot, while none of this group had anti-II by ELISA or dot blot. Antibody binding to beta2-GPI or prothrombin in both ELISA and dot blot was significantly reduced by phospholipid liposomes mixed together with beta2-GPI or prothrombin, whereas liposomal eluants retained it in both assays. Parallel fluid-phase inhibition experiments using increasing concentrations (up to 200 microg/ml) of beta2-GPI or prothrombin demonstrated that antibody binding reduction was more evident on dot blot than on ELISA. It was almost completely abolished on dot blot, while on ELISA a moderate inhibition was achieved even at the highest protein concentration. However, antibody binding on ELISA was virtually abolished when diluted sera were incubated with high protein concentrations applied to nitrocellulose membranes. We could infer that ELISA and dot blot detect antibodies with some differences in avidity but directed against native epitopes on beta2-GPI and prothrombin.

Adolescent↗
PubMed1998

High risk of cerebral-vein thrombosis in carriers of a prothrombin-gene mutation and in users of oral contraceptives.

BACKGROUND: Idiopathic cerebral-vein thrombosis can cause serious neurologic disability. We evaluated risk factors for this disorder, including genetic risk factors (mutations in the genes encoding factor V and prothrombin) and nongenetic risk factors (such as the use of oral contraceptive agents). We compared the prevalence of these risk factors in 40 patients with cerebral-vein thrombosis, 80 patients with deep-vein thrombosis of the lower extremities, and 120 healthy controls. The G1691A mutation in the factor V gene and the G20210A prothrombin-gene mutation, which are established genetic risk factors for venous thrombosis, were studied. We also assessed the use of oral contraceptives and other risk factors for thrombosis. RESULTS: The prevalence of the prothrombin-gene mutation was higher in patients with cerebral-vein thrombosis (20 percent) than in healthy controls (3 percent; odds ratio, 10.2; 95 percent confidence interval, 2.3 to 31.0) and was similar to that in patients with deep-vein thrombosis (18 percent). Similar results were obtained for the mutation in the factor V gene. The use of oral contraceptives was more frequent among women with cerebral-vein thrombosis (96 percent) than among controls (32 percent; odds ratio, 22.1; 95 percent confidence interval, 5.9 to 84.2) and among those with deep-vein thrombosis (61 percent; odds ratio, 4.4; 95 percent confidence interval, 1.1 to 17.8). For women who were taking oral contraceptives and who also had the prothrombin-gene mutation (seven patients with cerebral-vein thrombosis but only one control), the odds ratio for cerebral-vein thrombosis rose to 149.3 (95 percent confidence interval, 31.0 to 711.0). CONCLUSIONS: Mutations in the prothrombin gene and the factor V gene are associated with cerebral-vein thrombosis. The use of oral contraceptives is also strongly and independently associated with the disorder. The presence of both the prothrombin-gene mutation and oral-contraceptive use raises the risk of cerebral-vein thrombosis further.

Adolescent↗
PubMed2000

Prothrombin and factor V mutations in women with a history of thrombosis during pregnancy and the puerperium.

BACKGROUND: Venous thromboembolism is a leading cause of morbidity and mortality during pregnancy and the puerperium. However, the role of mutations in the prothrombin and factor V genes and other thrombophilic abnormalities as risk factors for thromboembolism in women during pregnancy and the pueperium is not known. METHODS: In a study of 119 women with a history of venous thromboembolism during pregnancy and the puerperium and 233 age-matched normal women, we measured the activity of antithrombin, protein C, protein S, and lupus anticoagulant. We also performed genetic analyses to detect the G1691A mutation in the factor V gene (factor V Leiden), the G20210A mutation in the prothrombin gene, and the C677T mutation in the methylenetetrahydrofolate reductase gene. Blood samples were obtained at least three months post partum or after the cessation of lactation. RESULTS: Among the women with a history of venous thromboembolism, the prevalence of factor V Leiden was 43.7 percent, as compared with 7.7 percent among the normal women (relative risk of venous thromboembolism, 9.3; 95 percent confidence interval, 5.1 to 16.9); that of the G20210A prothrombin-gene mutation, 16.9 percent as compared with 1.3 percent (relative risk, 15.2; 95 percent confidence interval, 4.2 to 52.6); and that of both factor V Leiden and the G20210A prothrombin-gene mutation 9.3 percent as compared with 0 (estimated odds ratio, 107). Assuming an overall risk of 1 in 1500 pregnancies, the risk of thrombosis among carriers of factor V Leiden was 0.2 percent, among carriers of the G20210A prothrombin-gene mutation, 0.5 percent, and among carriers of both defects, 4.6 percent, as calculated in a multivariate analysis. CONCLUSIONS: The G20210A prothrombin-gene mutation and factor V Leiden individually are associated with an increased risk of venous thromboembolism during pregnancy and the puerperium, and the risk among women with both mutations is disproportionately higher than that among women with only one mutation.

Adolescent↗
PubMed1977

Amino acid sequence of human prothrombin fragments 1 and 2.

The amino acid sequence of the nonthrombin half of human prothrombin is presented. Prothrombin fragment 1 has 155 amino acid residues as compared with 156 for the bovine equivalent. Ten gamma-carboxyglutamic acid residues are at the same location in each species. Human prothrombin fragment 2 contains 118 amino acid residues, as does the similar bovine fragment. Comparing bovine and human prothrombin fragment 1 we found 131 residues to be identical (84%). In prothrombin fragment 2, 84 residues were identical (71%). Assuming a time span of 90 million years since the radiation of several orders of placental mammals, prothrombin fragments 1 and 2 incorporated one substitution site per 100 amino acid sites every 11.2 and 6.3 million years, respectively. Internal homology is acribed to partial gene duplication, with the most likely crossover point located between residues 60-61 and residues 165-166.

Amino Acid Sequence↗
PubMed1980

Cloning and analysis of a cDNA coding for bovine prothrombin.

Poly(A)-RNA enriched for prothrombin was isolated by specific immunoprecipitation of bovine liver polysomes. Prothrombin consisted of about 8% of the cell-free translation products of this RNA. A double-stranded cDNA was synthesized by using reverse transcriptase (RNA-dependent DNA nucleotidyltransferase) and made blunt-ended with nuclease S1. After tailing with dCTP and terminal transferase, the double-stranded cDNA was annealed to pBR322 DNA that had been cleaved previously at the single Pst I site and similarly tailed with dGTP. The resulting plasmids were used to transform Escherichia coli strain RR1 under P3-EK1 conditions. Sixty-three tetracycline-resistant clones were obtained that hybridized to 32P-labeled cDNA synthesized from prothrombin-enriched mRNA. Recombinants containing cDNA to prothrombin mRNA sequences were screened by a solution hybridization assay with a [3H]cDNA synthesized from mRNA. This enriched mRNA was 50% prothrombin mRNA, as determined by a reticulocyte lysate translation assay. Three positive clones were identified by this assay; they contained bovine DNA inserts of 700, 500, and 400 base pairs. The DNA sequence of the 700-base-pair insert was then determined. This recombinant plasmid contained DNA coding for the carboxyl-terminal 160 residues of bovine prothrombin followed by a noncoding region of 119 base pairs and a poly(A) tail of 60 base pairs.

Amino Acid Sequence↗
PubMed2005

Third trimester nonrecurrent fetal loss is associated with factor V Leiden and prothrombin gene mutations.

OBJECTIVE: To determine the role of factor V Leiden and prothrombin gene mutation in the pathogenesis of unexplained second and third trimester nonrecurrent fetal loss. MATERIALS AND METHODS: One hundred and fourteen women with unexplained nonrecurrent late fetal loss made up the study group, and 106 normal pregnant women with a history of delivery of at least one healthy fetus and no history of late fetal loss made up the control group. The study group was further divided into two subgroups: second (n = 36) and third (n = 78) trimester fetal loss. All women were tested for factor V Leiden and G20210A prothrombin gene mutations. RESULTS: Twenty-one (18.4%) of the women in the study group and seven (6.6%) of the women in the control group were heterozygous carriers of factor V Leiden mutation (OR = 3.19). Eleven (9.6%) of the women in the study group and three (2.8%) of the women in the control group were heterozygous carriers of prothrombin gene mutation (OR = 3.66). In assessing with regard to trimesters, 18 (23%) factor V Leiden and 10 (12.8%) prothrombin gene mutations were present in the group of third trimester fetal loss (OR = 4.24 and OR = 5.04, respectively). Three (8.3%) factor V Leiden and one (2.7%) prothrombin gene mutation were detected in women with second trimester fetal loss (OR = 1.28 and OR = 0.40, respectively). CONCLUSION: Factor V Leiden and prothrombin gene mutations were associated with third trimester nonrecurrent fetal loss. These mutations should be screened in women with third trimester but not second trimester unexplained nonrecurrent late fetal loss.

Abortion, Spontaneous↗
PubMed2001

Prothrombin 20210 G: a mutation and Factor V Leiden mutation in women with a history of severe preeclampsia and (H)ELLP syndrome.

OBJECTIVE: The 20210 G-A prothrombin gene variant and the Factor V Leiden mutation are mutations associated with venous thrombotic risk. The aim of our study was to assess the prevalence of these specific mutations in women with a history of preeclampsia or hemolysis elevated liver enzymes, and low platelet count [(H)ELLP] syndrome and their influence on perinatal outcome. In addition, the association with venous thromboembolism was assessed. METHODS: One hundred fourteen (114) women with a history of preeclampsia or (H)ELLP syndrome were investigated at least 3 months' postpartum for the presence of 20210 G-A prothrombin gene variant and Factor V Leiden mutation. RESULTS: Four (3.5%) of the women had the 20210 G-A prothrombin gene variant, four (3.5%) women had the Factor V Leiden mutation, and one of these women carried both mutations. The prevalence of prothrombin 20210 G-A prothrombin and Factor V Leiden mutation in women with severe preeclampsia or (H)ELLP syndrome were comparable with the prevalence in the general Dutch population. The odds ratio for thromboembolism for carriers versus noncarriers was 22 (95% confidence interval: 1.7-303). Perinatal mortality was not significantly higher in women with any mutation [odds ratio: 1.5 (0.2-9.5)]. CONCLUSIONS: Although our study confirms that prothrombin 20210 G-A mutation and Factor V Leiden mutation are important genetic risk factors associated with thrombotic risk, these mutations appear not related to perinatal outcome in women with preeclampsia or (H)ELLP syndrome. It is unlikely that these mutations are of major importance for the development of severe preeclampsia or (H)ELLP syndrome.

Adult↗
PubMed1986

Assembly of the prothrombin activator complex on rabbit alveolar macrophage high-affinity factor Xa receptors. A kinetic study.

Efficient prothrombin activation occurs after assembly of factors Va, Xa, and phospholipid surface cofactor as a multimolecular complex. These components are provided by platelets and plasma within the vascular space, but molecules and membranes for prothrombin activator assembly in extravascular spaces have not been identified. In the present study, purified alveolar macrophages were found to produce high-affinity factor Xa receptors that mediate formation of enzymatic prothrombinase complexes and rapid prothrombin to thrombin conversion in the absence of exogenous factor V/Va or platelets. Thus, in reaction mixtures with alveolar macrophages cultured for 20 h in serum-free medium, the thrombin formation rate was 152 nM/min/0.66 X 10(6) cells, after adding prothrombin (1.5 microM), Ca2+ (5 mM), and factor Xa (3.7 nM). The observed Kd of factor Xa interaction with macrophage receptors is 2.1 +/- 0.94 X 10(-10) M. Kinetic analysis and inhibition studies using isolated factor V and anti-factor V antibody show that macrophage Xa receptors are functionally and antigenically similar to plasma factor V. By contrast, freshly isolated cells lacked receptors promoting prothrombin conversion at high rates. Inhibitors of protein synthesis and glycosylation, puromycin and monensin, respectively, abrogated production of Xa receptors in culture. Additionally, subcellular fractionation and enzyme-marker studies (alkaline phosphodiesterase I) indicate that internal and external membranes of alveolar macrophages have phospholipid surface cofactor activity required for prothrombinase complexes. Pulmonary surfactant is also shown to express this cofactor activity. Alveolar macrophages and surfactant comprise an efficient prothrombin activator system that is independent of plasma factor V. This system may facilitate rapid extravascular alveolar thrombin formation even at very low concentrations of factor Xa during lung defense reactions to inflammation or edema.

Animals↗
PubMed1984

Proficiency testing and standardization of prothrombin time: effect of thromboplastin, instrumentation, and plasma.

Prothrombin times accumulated from ten different proficiency testing surveys were analyzed in terms of a linear additive model described by Evatt et al (Clin Lab Haemat 1981; 3:331-342). Different types of lyophilized plasma samples were used, i.e., plasmas artificially depleted of coagulation factors by adsorption to aluminum hydroxide, and pooled plasmas of patients receiving coumarin drugs. For each plasma sample, both instruments and thromboplastins had a highly significant effect on the prothrombin time. For most instruments and thromboplastins, a good correlation was found between instrument effect or thromboplastin effect and the mean prothrombin time if various artificially depleted plasma samples from a single manufacturer were used. Artificially depleted plasmas from a second manufacturer gave different relationships between estimated effects and mean prothrombin time. Relationships based on lyophilized pooled patient plasmas were different from those of artificially depleted plasmas from either manufacturer. The potential use of the additive linear model for standardization of the prothrombin time in monitoring oral anticoagulant therapy is discussed. Additional studies are required to establish the suitability of this model to define a universal scale for prothrombin times of fresh plasma samples of anticoagulated patients. If suitable, the model can be linked to the International Normalized Ratio proposed by the World Health Organization.

Analysis of Variance↗
PubMed1989

Cost effectiveness of monitoring warfarin therapy using standard versus capillary prothrombin times.

The authors assessed the cost effectiveness of monitoring warfarin therapy guided by standard plasma prothrombin times performed on blood samples obtained by venipuncture versus prothrombin times performed on capillary whole blood samples obtained by fingerstick. Twenty patients receiving long-term oral anticoagulation had either standard or capillary prothrombin times determined every other week for eight weeks in a cross-over design. All time intervals were monitored, including receptionist, secretarial, nursing, phlebotomy, etc., and costs for all materials, procedures, and labor were calculated. The total cost per test by the capillary whole blood prothrombin time method was significantly less than by standard prothrombin time methods ($7.55 vs. $15.64) even though the nurse-patient encounter time was greater per test for the capillary method (12.4 minutes vs. 8.3 minutes). The management of oral anticoagulation guided by prothrombin times performed on instrumentation designed to sample capillary whole blood should result in a significant cost savings, and because of the immediate availability of results, provide the potential for improved health care.

Administration, Oral↗
PubMed1992

The relation of prothrombin times to coronary heart disease risk factors among men aged 31-45 years.

Although levels of coagulation factor VII and fibrinogen are predictive of cardiovascular disease, relatively little data describe hemostatic characteristics in healthy populations. The cross-sectional associations between the prothrombin time, a measure of the activity of the extrinsic and common pathways of coagulation, and traits associated with the risk of cardiovascular disease were therefore examined among 3,604 white and 514 black, male, US Army veterans aged 31-45 years. The prothrombin time measurements, performed in 1985 and 1986, were precise, with an intraclass correlation of 0.98 (202 pairs). Overall, the mean prothrombin time was 12.4 seconds (standard deviation, 0.4 seconds), and 11 percent of the men had a value of less than 12 seconds. Many of the observed associations with the prothrombin time paralleled those that have been reported with clotting factor VII and fibrinogen. The mean prothrombin time was 0.15 seconds shorter among whites than among blacks and was 0.2 seconds shorter among current cigarette smokers than among men who had never smoked. Inverse associations were also seen with relative weight and with levels of total cholesterol and triglycerides (r = -0.09 to -0.16). All associations were statistically significant at the 0.01 level, and the examined characteristics could jointly account for about 12 percent of the variability in prothrombin times. Additional data on characteristics related to coagulation may help elucidate the natural history of cardiovascular disease and aid in the design of clinical trials.

Adult↗
PubMed1999

Fibroblasts, glial, and neuronal cells are involved in extravascular prothrombin activation.

A membrane-associated prothrombin activator (MAPA) was found on various cultured cells derived from non-hematopoietic cells [Sekiya, F. et al. (1994) J. Biol. Chem. 269, 32441-32445]. In this study, we investigated the enzymatic properties of this enzyme using protease inhibitors. While the metalloproteinase inhibitor, o-phenanthroline, had no effect, some Kunitz type serine protease inhibitors attenuated MAPA activity. Recombinant tissue factor pathway inhibitor (rTFPI) also markedly reduced the activity (IC(50), 1. 3+/-0.6 x 10(-10) M). MAPA activity is, therefore, most likely to be due to factor Xa. We evaluated the effect of exogenous factor Xa on MAPA activity. Factor Xa-dependent prothrombin activation was observed on fibroblast cells (apparent K(d), 1.47+/-0.72 nM). Activation was also observed on glial and neuronal cells, which expressed MAPA activity. These results imply that membrane-bound factor Xa results in MAPA activity on these cells. Therefore, we considered the involvement of factor Va, a component of prothrombinase, in this activity. We examined whether or not the prothrombinase complex is assembled on these cells. Prothrombin was activated in a manner dependent on both exogenous factor Xa and factor Va (apparent K(d) of 0.51-1.81 nM for factor Va). These results indicate that the prothrombinase complex forms specifically on various extravascular cells. Although the prothrombinase complex can be assembled on monocytes and lymphocytes, it is not known why these cells can activate prothrombin specifically. These cells which have the capacity for prothrombin activator activity could also activate factor X; i.e. cells with factor X activation activity were able to convert prothrombin. These observations suggest that thrombin was generated via two procoagulant activities; factor X activation and subsequent prothrombinase complex formation on the surface of these cells. This mechanism may explain the various pathological states involving or resulting from extravascular thrombin and fibrin formation.

Animals↗
PubMed1985

Enzymatic properties of staphylothrombin, an active molecular complex formed between staphylocoagulase and human prothrombin.

Staphylocoagulase with a molecular weight of 64,000 and subspecies ranging in molecular weight from 36,000 to 64,000 were purified by affinity column chromatography on bovine prothrombin-Sepharose 4B from the culture filtrates of the Staphylococcus aureus strains, st-213 and 104. The samples containing all molecular species from both strains had the same NH2-terminal sequence, Ile-Val-Thr-Lys-Asp-Tyr-Ser-Lys-Glu-, implying that the molecular heterogeneity was due to proteolytic degradation to some extent of the COOH-terminal portion during cultivation or purification. Staphylocoagulase (Mr = 64,000) from strain st-213 formed an active complex, "staphylothrombin," with human prothrombin in a molar ratio of 1 to 1.1. Staphylothrombin was unstable at 37 degrees C and some portions of staphylocoagulase in the complex were rapidly degraded into small fragments, together with the fragmentation of prothrombin into prethrombin 1 and prothrombin fragment 1. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and subsequent fluorography for the products of prothrombin activation by staphylocoagulase in the presence of [3H]diisopropylphosphofluoridate (DFP) demonstrated the formation of a DFP-sensitive active site in the prothrombin molecule, and no cleavage of the Arg-Ile bond linking the A and B chains of alpha-thrombin was found. The enzymatic properties including the pH-dependency of the activity, substrate specificity and behavior towards thrombin inhibitors of staphylothrombin differed from those of alpha-thrombin, although the active site titration of staphylothrombin with p-nitrophenyl-p'-guanidinobenzoate showed 0.95 +/- 0.2 mol of active site/mol of enzyme.

Amidohydrolases↗
PubMed1999

Post-traumatic basilar artery thrombosis in a young man with atrial septum aneurysm and prothrombin gene G20210A polymorphism.

Prothrombin gene G20210A polymorphism has been recently identified as a cause of venous thrombosis. However the association between this mutation and arterial thrombosis remains uncertain. Some authors have suggested that the polymorphism in the 3' region of the prothrombin gene may precipitate cerebral arterial thrombosis in young patients with prothrombotic conditions. We report a case of post-traumatic basilar artery thrombosis in a young patient carrier of the prothrombin gene G20210A polymorphism. Thirty-six hours after sustaining a head injury in the occipital region, a young man developed vomiting, headache, dizziness and truncal ataxia, without signs of focal impairment. Magnetic resonance imaging and selective angiography carried out 2 days later showed an obstruction of the basilar artery, with infarction of the right cerebellar region. A transthoracic echocardiogram showed a patent foramen ovale with little left-to-right shunt and an aneurysm of the interatrial septum. Blood examination showed a heterozygous status for prothrombin gene G20210A polymorphism. We conclude that this prothrombin gene mutation and the coexisting particular head injury and interatrial septal aneurysm could have contributed simultaneously to the development of basilar artery occlusion and cerebellar infarction. We suggest that in selected cases of cerebellar ischemia a prothrombin gene G20210A polymorphism should be considered.

Adult↗
PubMed2004

No effect of the prothrombin G20210A mutation on protein C activation in a large kindred with type I protein C deficiency.

Previously, we observed a positive association of prothrombin concentrations with thrombin generation (fragment 1 + 2) and thrombin activity (fibrinopeptide A), but no association with protein C activation peptide levels. We further evaluated a potential beneficial effect of increased prothrombin concentrations on activated protein C generation by assessing the plasma concentration of activated protein C in complex with protein C inhibitor (APC-PCI). Blood samples were used from 195 family members of a large French-Canadian kindred with type I protein C deficiency due to a 3363C insertion in the protein C gene. We utilized a new and highly sensitive assay for measuring the concentration of APC-PCI complex as a measure of the level of activation of protein C. Means of the plasma concentrations of the APC-PCI complex were compared among carriers and non-carriers of the prothrombin G20210A mutation. Protein C activity levels were positively associated with APC-PCI complex plasma concentrations; however, APC-PCI complex levels were not different for carriers of the prothrombin G20210A mutation than for non-carriers. Thus, carriers of the prothrombin G20210A mutation do not have increased protein C activation despite the increased thrombin generation resulting from the higher prothrombin concentrations associated with the G20210A mutation.

Blood Coagulation Tests↗
PubMed1999

Heterozygous prothrombin gene mutation: a new risk factor for early renal allograft thrombosis.

BACKGROUND: Underlying thrombophilic disorders increase the risk of early allograft loss after renal transplantation. We report three cases of early graft thrombosis in two carriers of a recently discovered prothrombotic variation of the prothrombin gene. CASE REPORTS: The first patient, an adolescent girl, developed multiple thrombotic shunt occlusions after the initiation of hemodialysis until continuous cumarin anticoagulation was instituted. During living-related kidney transplantation, peracute thrombosis of the renal arteries and veins occurred during surgery despite excellent intraoperative conditions and continuous low-dose heparinization. A few hours after reperfusion of the organ by immediate thrombectomy and intrarenal fibrinolysis, an irreversible rethrombosis occurred. A detailed evaluation of the coagulation system showed highly elevated prothrombin protein activity and concentrations. A heterozygous G-->A transition at position 20210 of the prothrombin gene was identified. Hemodialysis was resumed using recombinant hirudin, a direct and selective thrombin inhibitor, as an anticoagulant. The second patient, a girl with end-stage renal failure due to atypical hemolytic uremic syndrome, lost two cadaver kidney allografts, each time by massive thrombosis a few days after transplantation. In this patient also, elevated prothrombin activity and concentrations were present and a heterozygous G-->A transition at position 2210 of the prothrombin gene was detected. CONCLUSIONS: The prothrombin gene mutation is a new risk factor for thrombotic complications both on hemodialysis and after renal transplantation. It may be useful to screen for this disorder in the pretransplant thrombophilia work-up.

Adolescent↗