Cancer-associated thrombosis by cancer sites and inherited factors in a prospective population-based cohort.

Cancer-associated thrombosis (CAT) is common and associated with mortality. We estimated CAT rate by cancer sites and inherited factors among cancer patients from the UK Biobank (N =70,406). The 12-month CAT rate after cancer diagnosis was 2.37% overall but varied considerably among cancer sites. Among the 10 cancer sites classified as 'high-risk' of CAT by the National Comprehensive Cancer Network guidelines, 6 had CAT rate <5%. In contrast, 5 cancer sites classified as 'average-risk' by the guidelines had CAT rate >5%. For inherited risk factors, both known mutation carriers in two genes (F5/F2) and polygenic score for venous thromboembolism (VTE) (PGSVTE) were independently associated with increased CAT risk. While F5/F2 identified 6% patients with high genetic-risk for CAT, adding PGSVTE identified 13 % patients at equivalent/higher genetic-risk to CAT than that of F5/F2 mutations. Findings from this large prospective study, if confirmed, provide critical data to update guidelines for CAT risk assessment.

Hyperbaric oxygen treatment results in a group of Turkish central retinal artery occlusion patients with a combined presence of thrombophilic mutations.

Background: Central retinal artery occlusion (CRAO) is a rare ocular-ischemic syndrome causing irreversible blindness. Its pathophysiology has not been clarified, and no targeted therapies are available yet. Hyperbaric oxygen (HBO2) therapy is already an approved therapy for CRAO and has been shown to improve the visual acuity of CRAO patients safely. However, further clinical data are required to classify HBO2 therapy as a type-I general agreement for CRAO. Materials and Methods: Eleven patients with non-arteritic CRAO were enrolled. Patient demographics, medical history, detailed eye examinations, HBO2 therapy results, pre-/post HBO2 therapy visual acuity measurements and genotypes for common thrombophilic mutations (Factor V G1691A Leiden, Factor II G20210A, MTHFR A1298C, MTHFR C677T, and PAI-1-675 4G/5G) were obtained. Result: Six patients (54%) responded to HBO2 therapy compared to five non-responders (46%). Patients admitted before 12 hours responded well to HBO2 therapy. No systemic diseases nor advanced age were statistically correlated to CRAO. A combination of mutations rather than single mutations for each patient could be seen as responsible for CRAO. No Factor V G1691A Leiden mutations and only one FII G20210A mutation were observed. Eight patients (72%) had MTHFR 677T allele, five patients (45%) had MTHFR 1298C allele, and 10 patients (91%) had the PAI-1-675 4G allele. Conclusion: Not a single mutation but a combination of mutations and other unknown factors probably lead to CRAO, and if intervention is timely, HBO2 therapy offers improvement in visual acuity safely.

Plasma fibrin clot properties in the G20210A prothrombin mutation carriers following venous thromboembolism: the effect of rivaroxaban.

We sought to investigate whether the G20210A prothrombin mutation modifies plasma fibrin clot properties in patients after venous thromboembolism (VTE) and how rivaroxaban treatment affects these alterations. We studied 34 prothrombin mutation heterozygous carriers and sex- and age-matched 34 non-carriers, all at least three months since the first VTE episode, before and during treatment with rivaroxaban. Clot permeability (Ks) and clot lysis time (CLT) with or without elimination of thrombin activatable fibrinolysis inhibitor (TAFI) were assessed at baseline, 2-6 hours (h) after and 20-25 h after intake of rivaroxaban (20 mg/day). At baseline, the prothrombin mutation group formed denser clots (Ks -12 %, p=0.0006) and had impaired fibrinolysis (CLT +14 %, p=0.004, and CLT-TAFI +13 %, p=0.03) compared with the no mutation group and were similar to those observed in 15 healthy unrelated prothrombin mutation carriers. The G20210A prothrombin mutation was the independent predictor for Ks and CLT before rivaroxaban intake. At 2-6 h after rivaroxaban intake, clot properties improved in both G20210A carriers and non-carriers (Ks +38 %, and +37 %, CLT -25 % and -25 %, CLT-TAFI -20 % and -24 %, respectively, all p<0.001), but those parameters were worse in the prothrombin mutation group (Ks -12.8 %, CLT +17 %, CLT-TAFI +13 %, all p<0.001). Rivaroxaban concentration correlated with fibrin clot properties. After 20-25 h since rivaroxaban intake most clot properties returned to baseline. Rivaroxaban-related differences in clot structure were confirmed by scanning electron microscopy images. In conclusion, rivaroxaban treatment, though improves fibrin clot properties, cannot abolish more prothrombotic fibrin clot phenotype observed in prothrombin mutation carriers following VTE.

Development and evaluation of analytical performance of a fully automated chemiluminescent immunoassay for protein induced by vitamin K absence or antagonist II.

OBJECTIVES: Protein induced by vitamin K absence or antagonist II (PIVKA-II), an abnormal form of prothrombin, has been used as an aid in the diagnosis of hepatocellular cancer (HCC) as a tumor marker. We developed a fully automated quantitative immunoassay for PIVKA-II on the ARCHITECT® i systems. The aim of this study was to evaluate the analytical performance of this assay. DESIGN AND METHOD: Assay imprecision, sensitivity, dilution linearity, high dose hook effect, sample type equivalency, assay interferences of potential interfering materials and correlation with Picolumi PIVKA-II (Eidia, Tokyo, Japan) were evaluated. RESULTS: The percentage coefficient of variation (%CV) of total imprecision ranged from 2.8% to 5.4% with 10 levels of samples. The limit of blank (LoB), limit of detection (LoD), and limit of quantitation (LoQ) were less than 0.63 mAU/mL, 1.62 mAU/mL, and 8.25 mAU/mL, respectively. Linearity up to 30,000 mAU/mL, no high dose hook effect, no difference among sample types and no interference of common drugs and endogenous substances were observed. Correlation study with the Picolumi PIVKA-II gave a correlation coefficient of 0.93 and a regression slope of 1.07. CONCLUSIONS: The results demonstrate that the fully automated prototype ARCHITECT PIVKA-II assay is an accurate, highly sensitive and precise assay for the measurement of PIVKA-II levels in human sera and plasmas.

[Possibility of the natural product extracted from Calophyllum Brasiliense].

During our search for cancer chemopreventing compounds derived from plant sources, we discovered that the natural product GUT-70, isolated from the stem bark of Calophyllum Brasiliense collected in Brazil, significantly inhibited the growth of leukemic cells via the induction of caspase-mediated and p53-independent apoptosis. Furthermore, we synthesized BNS-22 as a derivative of GUT-70, which showed more antiproliferative activity against human cancer cells than GUT-70. GUT-70 and BNS-22 commonly inhibited ubiquilin-1, suggesting that a GUT-70 derivative might become a First in Class agent. In addition, GUT-70 and BNS-22 inhibited HSP90 and topoisomerase II, respectively. Recently, we also found that GUT-70 inhibited HIV replication. These findings indicated that GUT-70 could serve as a lead compound to develop novel therapeutic agents against cancer and HIV-1 infection.

Estrogen receptor alpha augments changes in hemostatic gene expression in HepG2 cells treated with estradiol and phytoestrogens.

Phytoestrogens are popular alternatives to estrogen therapy however their effects on hemostasis in post-menopausal women are unknown. The aim of this study was to determine the effect of the phytoestrogens, genistein, daidzein and equol on the expression of key genes from the hemostatic system in human hepatocyte cell models and to determine the role of estrogen receptors in mediating any response seen. HepG2 cells and Hep89 cells (expressing estrogen receptor alpha (ERα)) were incubated for 24 h with 50 nM 17ß-estradiol, genistein, daidzein or equol. Tissue plasminogen activator (tPA), plasminogen activator inhibitor-1 (PAI-1), Factor VII, fibrinogen γ, protein C and protein S mRNA expression were determined using TaqMan PCR. Genistein and equol increased tPA and PAI-1 expression in Hep89 cells with fold changes greater than those observed for estradiol. In HepG2 cells (which do not express ERα), PAI-1 and tPA expression were unchanged. Increased expression of Factor VII was observed in phytoestrogen treated Hep89 cells but not in similarly treated HepG2s. Prothrombin gene expression was increased in equol and daidzein treated HepG2 cells in the absence of the classical estrogen receptors. These data suggest that phytoestrogens can regulate the expression of coagulation and fibrinolytic genes in a human hepatocyte cell line; an effect which is augmented by ERα.

The selective estrogen receptor modulator DT56a (Femarelle) does not affect platelet reactivity in normal or thrombophilic postmenopausal women.

OBJECTIVE: The purpose of this study was to assess the effect of DT56a (Femarelle), a selective estrogen receptor modulator, on platelet function in normal and thrombophilic women being treated for severe menopausal symptoms. METHODS: The Platelet Function Analyzer-100 (PFA-100) was used to asses platelet reactivity at baseline and after 8 weeks of treatment with Femarelle (644 mg/d in divided doses) in 25 symptomatic postmenopausal women with normal clotting times and seven symptomatic women with shortened clotting times (<61 s). The PFA-100 measure of closure time is considered equal to clotting time in assessing clotting function and platelet adhesion, aggregation, and blood coagulation factors. Closure times were measured after 3 and 8 weeks in all participants and at 1 year in the women with shortened clotting times. The nonparametric Wilcoxon signed rank test was used to assess the changes between baseline and each of the three subsequent measurements. RESULTS: Pretreatment study of all seven women with shortened closure times confirmed abnormalities associated with thrombophilia: four women were heterozygous for the factor V Leiden gene mutation, one was heterozygous for the prothrombin gene mutation, one was found to have protein S deficiency, and one had increased anticardiolipin antibodies. All participants reported improved symptoms during the treatment period. No significant change in closure times was found in the normally clotting participants after 3 or 8 weeks of Femarelle therapy (P > 0.26). No significant change in closure time was seen in the seven thrombophilic women after 3 or 8 weeks or 1 year of Femarelle treatment (P > 0.26). The regression curve for measures over time was not significant (P = 0.26). CONCLUSIONS: Femarelle, whose active ingredient is DT56a, did not adversely affect platelet reactivity as measured by PFA closure times in symptomatic thrombophilic postmenopausal women or normal controls. Femarelle, a novel selective estrogen receptor modulator that inhibits menopausal symptoms without thrombogenicity, may offer a new clinical choice for therapy of symptomatic postmenopausal women.

Genistein alters coagulation gene expression in ovariectomised rats treated with phytoestrogens.

Recent data has shown that hormone therapy (HT) increases the risk of cardiovascular and thromboembolic disease, particularly in users of oral HT. Phytoestrogens are popular alternatives to oestrogen therapy; however, their effects on cardiovascular risk are unknown. We investigated the effect of the phytoestrogen, genistein on the expression of genes and proteins from the haemostatic system in the liver in an ovariectomised rat model. Fifty-nine virgin female Sprague-Dawley rats were fed with soy-free chow supplemented with 17ß estradiol (E2) (daily uptake 0.19 or 0.75 mg/kg body weight), or genistein (daily uptake 6 or 60 mg/kg body weight), for three months and compared to soy-free control rats. Gene expression of prothrombin, factor VII, fibrinogen alpha and fibrinogen beta was increased with E2 and genistein compared to the soy-free control group (p<0.001). Genistein increased factor VII significantly more than E2 (p<0.005). Plasminogen mRNA was increased in both treatment groups compared to the soy-free control, with genistein expression significantly higher than E2 (p<0.001). Tissue plasminogen inhibitor (tPA), plasminogen activator inhibitor-1 (PAI-1) and C-reactive protein (CRP) expression were also increased in both groups relative the soy-free control. Results of protein analysis largely concurred with those of the mRNA. Oestrogen receptor ß (ERß) was undetected while oestrogen receptor α (ERα) was detected in each sample group. Genistein can increase the expression of coagulation and fibrinolytic genes. This effect was similar and in some cases higher than 17ß estradiol. These results suggest that genistein may not be neutral with respect to the haemostatic system.

VKORC1 haplotypes influence the performance characteristics of PIVKAII for screening of hepatocellular carcinoma.

BACKGROUND: PIVKAII (protein induced by vitamin K absence), used for screening for hepatocellular carcinoma (HCC), is influenced by vitamin K epoxide reductase complex subunit 1 (VKORC1). VKORC1 haplotype frequency is significantly different in ethnic groups. We evaluated whether VKORC1 haplotypes could influence the performance characteristics of PIVKAII in screening for HCC. METHODS: A total 228 HCC patients and 258 patients with hepatitis B were recruited. Tumor size was measured in 76 patients with HCC. Serum PIVKAII concentrations and VKORC1 haplotype were determined in the cohort. Youden's index and ROC curves were used to compare the performance characteristics of PIVKAII in screening for HCC. RESULTS: In the HCC group and in patients with hepatitis B, serum PIVKAII concentrations were higher in VKORC1 rs2395612 TT carriers than in CC/CT carriers (50.34±72.18 vs. 11.98±27.45, p<0.05 in HCC group and 1.92±0.52 vs. 1.48±0.36, p<0.01). The estimated optimal cut-off value of PIVKAII for screening HCC was 2.0 and 3.0 ng/mL in CC/CT carriers and TT carriers, respectively. Furthermore, VKORC1 haplotypes also influenced the association of serum PIVKAII concentrations with HCC tumor size in patients with HCC. CONCLUSIONS: VKORC1 haplotypes influence the performance characteristics of PIVKAII for screening of HCC. Thus, measurement could be complementary for PIVKAII in HCC screening.

Thalidomide-dexamethasone as up-front therapy for patients with newly diagnosed multiple myeloma: thrombophilic alterations, thrombotic complications, and thromboprophylaxis with low-dose warfarin.

BACKGROUND: Venous thromboembolism (VTE) is a major complication of myeloma therapy recently observed with the increasing use of up-front thalidomide and dexamethasone (thal-dex). The pathogenesis of thal-induced VTE is not well recognized, and the role of prothrombotic factors, especially of thrombophilic abnormalities, is not yet determined. MATERIAL AND METHODS: Two hundred and sixty-six patients with newly diagnosed multiple myeloma (MM) were primarily treated with thal-dex in preparation for subsequent high-dose therapy and autologous stem-cell transplantation. Out of these 266 patients, 190 were evaluated for thrombophilic alterations at baseline, and 125 of them were also re-assessed after thal-dex therapy. RESULTS: The presence of genetic thrombophilic polymorphisms among patients with MM was superimposable to that of normal controls and was associated with a twofold increase in the relative risk of VTE. aAPCR and elevated factor VIII levels were frequent, albeit transient, alterations and were not associated with a significant increase in the risk of VTE. Two hundred and forty-six patients received a thromboprophylaxis with fixed low-dose warfarin (1.25 mg/day) during thal-dex therapy. Of these patients (or 10.6%), 26 had symptomatic VTE events. Their patients-years rate of VTE (35.5%) was significantly lower in comparison with the 86.2% rate recorded among the first 19 patients who initially entered the study and did not receive any kind of thromboprophylaxis (P = 0.043). CONCLUSIONS: On the basis of these data, a baseline thrombophilic work up is not recommended in patients with receiving up-front thal-dex. For these patients, fixed low-dose warfarin may be a valuable prophylaxis against VTE.

Influence of inherited and acquired thrombophilic defects on the clinical manifestations of mixed cryoglobulinaemia.

OBJECTIVE: To investigate the contribution of inherited and acquired thrombophilic defects to the clinical manifestations of mixed cryoglobulinaemia vasculitis. METHODS: The following thrombophilic defects were investigated in 64 consecutive patients with HCV-associated mixed cryoglobulinaemia: aPLs, lupus anti-coagulant, homocysteinaemia, protein C and protein S concentrations, activated protein C resistance, plasminogen activator inhibitor-1 4G4G and 5G5G genotypes, and the presence of mutations of factor V (Leiden and H1299R), of prothrombin (G20210A) and of methyl tetrahydrofolate reductase (C677T and A1298C). Additional variables were demographic data, duration of the disease, cryocrit level and vascular risk factors (diabetes, hypertension, hypercholesterolaemia and smoking habit). The following clinical manifestations of mixed cryoglobulinaemia were analysed as dependent covariates: severity of purpura, presence of necrotic skin ulcers, presence of peripheral neuropathy and presence of kidney disease. RESULTS: Logistic regression analysis identified hyperhomocysteinaemia as a risk factor for severe purpura (P < 0.0001) and for the presence of skin ulcers (P < 0.0001), whereas none of the other thrombophilic defects influenced the clinical presentation of mixed cryoglobulinaemia. Purpura improved in two patients after lowering homocysteine with vitamin supplementation. CONCLUSIONS: Hyperhomocysteinaemia may be a risk factor for severe cutaneous manifestations in mixed cryoglobulinaemia.

The carboxylation efficiency of the vitamin K-dependent clotting factors: studies with factor IX.

Haemophilia B is characterized by a deficiency of the gamma-carboxylated protein, factor IX (FIX). As a first step to optimize a gene therapy strategy to treat haemophilia B, we employed a previously described approach (Biochemistry 2000;39: 14322) of altering the propeptide of vitamin K-dependent proteins in vitro, to improve the carboxylation efficiency of FIX. Both native FIX and FIX with a prothrombin propeptide (proPT-FIX) produced recombinant FIX in vitro following transfection of their cDNAs into human embryonic kidney (HEK) 293 cells. Using hydroxyapatite chromatography to separate carboxylated from uncarboxylated FIX, we are able to show that >90% of FIX is gamma-carboxylated and that substituting the propeptide of prothrombin into FIX does not further increase the relative amounts of carboxylated material. These results demonstrate that the nature of the propeptide, per se is not the sole determinant of optimal carboxylation of FIX in our expression system in HEK 293 cells.

Hyperhomocysteinemia due to pernicious anemia leading to pulmonary thromboembolism in a heterozygous mutation carrier.

Pulmonary thromboembolism is a life-threatening condition resulting mostly from lower extremity deep-vein or pelvic-vein thrombosis. A 46-year-old woman was admitted to hospital with pain on the right side of the chest and hemoptysis. On laboratory analysis, D-dimer level was elevated. Computed tomographic pulmonary angiography revealed intravascular filling defects due to thrombi in right lower lobe pulmonary segmental arteries. Screening for thrombophilic states was normal except for heterozygous mutations of both prothrombin and methylene tetrahydrofolate reductase (MTHFR 677) genes. Homocysteine level was high, and vitamin B12 level and serum ferritin level were reduced. Serum antiparietal antibody was positive, and therefore, pernicious anemia was diagnosed along with iron-deficiency anemia. After the diagnoses were established, enoxaparin followed by warfarin was started in addition to oral vitamin B12, pyridoxine, thiamine, folic acid, and ferroglycine sulfate supplementation. At the end of 8 weeks of the replacement therapy, vitamin B12, folate, and homocysteine levels and red cell volume were found to be normal, with complete resolution of the thrombus confirmed by repeat computed tomographic pulmonary angiography. We conclude that hyperhomocysteinemia due to vitamin B12 deficiency associated with pernicious anemia might have decreased the threshold for thrombosis. In addition, the presence of heterozygous prothrombin and methylene tetrahydrofolate reductase mutations might serve as synergistic cofactors triggering pulmonary thromboembolism.

Homocysteine, folate and vitamin B(12) in puerperal cerebral venous thrombosis.

BACKGROUND AND OBJECTIVE: Hyperhomocysteinemia (hyper-Hcy) is a known risk factor for venous thrombosis, but few studies document the risk in puerperal cerebral venous thrombosis (CVT). Nutritional folate and vitamin B(12) deficiency can cause hyper-Hcy and pregnancy may contribute to this deficiency. We studied the association of plasma total homocysteine (tHcy), folate and vitamin B(12) levels with puerperal CVT through a case-control study. METHODS: Sixty women with puerperal CVT and 64 healthy puerperal controls were recruited. Plasma fasting tHcy was estimated by high pressure liquid chromatography using coulometric electrochemical detection. Vitamin B(12) and folate were measured by radioimmunoassay. Risk of puerperal CVT was estimated for each of the three variables. RESULTS: Adjusted odds ratio for the risk of puerperal CVT with hyper-Hcy (>90th percentile) was 10.8 (95% CI: 4.0-29.4; adjusted for vitamin B(12) and folate levels). Low folate and vitamin B(12) levels (<10th percentile) did not increase the risk for puerperal CVT. There was a significant inverse correlation between folate and tHcy levels (rho=-0.471, p<0.001). CONCLUSIONS: Hyperhomocysteinemia is associated with an increased risk of puerperal CVT occurring in Indian women and low folate levels contribute significantly to hyper-Hcy. Regular antenatal folate and vitamin B(12) supplementation is likely to lower puerperal tHcy levels, but its clinical benefit needs to be tested by large therapeutic trials.

Different outcome of six homozygotes for prothrombin A20210A gene variant.

Prothrombin G20210A gene variant (FII G20210A) is a risk factor for venous thrombotic disease while conflicting results have been reported for the risk of arterial thrombotic events. However, vascular episodes were absent in up to 40% of the 67 homozygotes for the G20210A described so far, which indicates that the clinical expression depends on additional risk/trigger factors. We describe six homozygotes for the G20210A variant, among which the first pair of siblings (cases n. 3 and 4) reported so far that displayed a strongly heterogeneous clinical outcome. Case 1, a female of 27 years, developed a full thrombosis of common femoral, superficial and popliteal veins. She assumed oral contraceptives in the last two years. Case n. 2, 34 years old, suffered of recurrent pregnancy loss in absence of any causative alteration. Cases n. 3 and n. 5 experienced arterial thrombotic disease, i.e., juvenile myocardial infarction (40 years old) and stroke (48 years old), respectively, in absence of other risk factors. Finally, cases n. 4 and 6 identified as homozygotes for the FII G20210A variant being consanguineous of symptomatic subjects bearing the variant, did not experience any episode of venous nor arterial disease. Both of them have chronic liver disease with an impairement of the prothrombin time INR. Thus, homozygotes for the G20210A are at risk for arterial (in addition to venous) thromobotic events; chronic liver disease might modulate this risk.

Effects of random allocation to vitamin E supplementation on the occurrence of venous thromboembolism: report from the Women's Health Study.

BACKGROUND: Supplementation with vitamin E may antagonize vitamin K in healthy adults, but it is unclear whether intake of vitamin E decreases the risk of venous thromboembolism (VTE). METHODS AND RESULTS: The Women's Health Study randomized 39,876 women > or = 45 years of age to receive 600 IU of natural source vitamin E or placebo on alternate days. Before randomization, 26,779 participants gave blood samples, which were used to determine factor V Leiden, G20210A prothrombin, and 677C>T MTHFR polymorphisms. Documented VTE (including deep vein thrombosis or pulmonary embolism) and unprovoked VTE (no recent surgery, trauma, or cancer diagnosis) were prospectively evaluated, secondary end points of the trial. During a median follow-up period of 10.2 years, VTE occurred in 482 women: 213 in the vitamin E group and 269 in the placebo group, a significant 21% hazard reduction (relative hazard, 0.79; 95% CI, 0.66 to 0.94; P=0.010). For unprovoked VTE, the hazard reduction was 27% (relative hazard, 0.73; 95% CI, 0.57 to 0.94; P=0.016). In subgroup analyses, the 3% of participants who reported VTE before randomization had a 44% hazard reduction (relative hazard, 0.56; 95% CI, 0.31 to 1.00; P=0.048), whereas women without prior VTE had an 18% hazard reduction (relative hazard 0.82; 95% CI, 0.68 to 0.99; P=0.040). Women with either factor V Leiden or the prothrombin mutation had a 49% hazard reduction associated with vitamin E treatment (relative hazard, 0.51; 95% CI, 0.30 to 0.87; P=0.014). CONCLUSIONS: These data suggest that supplementation with vitamin E may reduce the risk of VTE in women, and those with a prior history or genetic predisposition may particularly benefit.

Full-length cDNA cloning and protein three-dimensional structure modeling of porcine prothrombin.

Prothrombin is a vitamin K-dependent serine protease and plays pivotal roles in both procoagulant and anticoagulant pathway of hemostasis. In this study, we cloned the full-length cDNA of porcine prothrombin by cDNA library screening and SMART RACE technique. The full-length cDNA is 2027 bp, with a 1869 bp Open Reading Frame (ORF) coding 623 amino acids. The deduced protein of porcine prothrombin contains signal peptide, propeptide, Gla domain, two kringle domains and trypsin domain. Porcine prothrombin shares 86.15% nucleotide similarity and 83% amino acid similarity with human prothrombin. The trypsin domain is highly conserved between the two species with 92.1% amino acid identity. Macromolecular interaction sites comparison between porcine and human prothrombin suggests that the Gla domain in porcine prothrombin contains an additional potential gamma-carboxyglutamic acid site. However, a thrombin cleavage site (Arg284-Thr285) in its light chain is lost. When thrombin heavy chain is concerned, the most important functional sites such as catalytic triad DHS, RGD site, Na+ binding site and anion-binding exosite-I and II are highly conserved. However, great differences have been observed between residues 145 and 158 of heavy chain which is associated with thrombomodulin binding. Two important limited proteolysis sites at Ala150 and Lys154 were lost in porcine sequence, which would affect epsilon-thrombin and gammaT-thrombin generation. Comparison on 3-D protein models demonstrates that these proteins are obviously different in autolysis loop (Lys145 to Gly155). Compared with that of human prothrombin, variation at critical recognition sites would likely alter its binding affinity and reaction velocity, which would contribute to coagulation disorder when porcine liver is transplanted into human body.

Effect of Factor V Leiden and prothrombin G20210-->A mutations on thromboembolic risk in the national surgical adjuvant breast and bowel project breast cancer prevention trial.

BACKGROUND: In the National Surgical Adjuvant Breast and Bowel Project's Breast Cancer Prevention Project (BCPT), tamoxifen use was associated with an increased relative risk for venous thromboembolic events, including deep vein thrombosis and pulmonary emboli, compared with placebo. However, the involvement of hypercoagulability factors in this association is unclear. METHODS: To examine possible associations among the risk of venous thromboembolic events, tamoxifen use, and Factor V Leiden (FVL) and prothrombin G20210-->A (PT20210) mutations, which are involved in promoting blood coagulation, we used a nested, matched, case-control (1 : 4) design and compared women in the BCPT who had experienced venous thromboembolic events (n = 76) with women who did not (n = 295). FVL and PT20210 mutations were detected in genomic DNA that was isolated from blood samples collected at trial enrollment. RESULTS: Venous thromboembolic events occurred in 28 women (deep vein thrombosis in 22 and pulmonary emboli in six) who were taking placebo and in 53 women (deep vein thrombosis in 35 and pulmonary emboli in 18) who were taking tamoxifen (relative risk = 1.90, 95% confidence interval = 1.18 to 3.12). Excessive risk for venous thromboembolic events was observed only in the first 36 months of therapy. There were no differences in age, smoking, and race between the groups, but women with venous thromboembolic events had a higher body mass index than women without (mean +/- standard deviation, 30 kg/m(2) +/- 7.7 versus 27.1 +/- 5.6; P<.001). FVL and/or PT20210 mutations were found in nine women (four on tamoxifen and five on placebo) with venous thromboembolic events and in 20 control subjects (nine on tamoxifen and 11 on placebo). No associations were found between risk of venous thromboembolic events and mutation status in either treatment group. CONCLUSIONS: Venous thromboembolic disease in the BCPT women is associated with tamoxifen use and body mass index, but not with FVL and PT20210 mutations. Screening women at risk for breast cancer for FVL and/or PT20210 appears to offer no benefit in determining the risk of tamoxifen-associated thromboembolic events.

Effects of oxalate exposure on Madin-Darby canine kidney cells in culture: renal prothrombin fragment-1 mRNA expression.

It has been suggested that renal tubular cell damage induced by oxalic acid, one of the components of urinary calculi, may be involved in a variety of ways in the development of urolithiasis. During our study on a calculus related protein, renal prothrombin fragment-1 (RPTF-1), we noted that this is an inflammation related substance that mediates an acute inflammatory reaction, one of the original roles of prothrombin. RPTF-1 is a part of prothrombin that is a coagulation factor known to be expressed in the renal tubule. We examined whether oxalic acid may cause cytotoxic effects on tubular epithelial cells and whether such chemical stimulation may promote the translation of RPTF-1 mRNA into RPTF-1 proteins. We used Madin-Darby canine kidney (MDCK) cells derived from the distal tubule of a dog kidney. In this study, the effects of oxalic acid in culture solution at different concentrations on cytotoxicity were assessed using a MTT assay. The location of active oxygen species was identified using dichlorofluorescein diacetate. After the prothrombin sequence of RPTF-1 was confirmed in MDCK cells, RPTF-1 mRNA expression was determined by RT-PCR. The gene sequence of the same promoter area was ligated, and a luciferase sequence was inserted downstream of the vector. The target sequence was transfected into MDCK cells and the relation between oxalic acid and prothrombin promoter was examined. In addition, the variable expression of RPTF-1 mRNA was quantitatively compared depending on oxalic acid concentrations using real-time PCR. When cytotoxicity was investigated, cells were not damaged but, by contrast, were stimulated and activated under oxalic acid below a certain concentration. The relation between cytotoxicity on the cultured MDCK cell membrane and active oxygen species was confirmed. Luminescence in MDCK cells containing the luciferase gene was detected by the addition of oxalic acid, which activated the prothrombin promoter. A part of the prothrombin gene sequence in the MDCK cells was detected and an increase in the expression of RPTF-1 mRNA in MDCK cells by the addition of oxalic acid was confirmed using real-time PCR. Increased expression of prothrombin by adding oxalic acid has already been demonstrated in previous studies. In this study, however, RPTF-1 mRNA was promoted by oxalic acid and a direct association between oxalic acid and RPTF-1 is indicated. This finding shows that increased oxalic acid in urine induces the expression of RPTF-1 in tubular epithelial cells and thereby causes the generation of active oxygen species.