Low protein Z levels but not the protein Z gene G79A polymorphism are a risk factor for ischemic stroke

Background

Protein Z (PZ) is a vitamin K-dependent plasma protein that plays a role in both pro-and anticoagulant pathways, but its exact physiological function remains unclear. The aim of this study was to determine the association between the G79A PZ gene polymorphism in intron F, PZ levels and the occurrence of ischemic stroke.

Methods

We performed a case-control study in 118 Caucasian patients with first ever ischemic stroke or TIA confirmed by CT, and 113 age-and sex-matched population controls. Venous blood samples for PZ levels were collected 7 to 14 days and 3 months after stroke onset. Estimates of relative risk (odds ratios) were adjusted for vascular risk factors.

Results

The adjusted relative risk of ischemic stroke associated with PZ levels in the lowest quartile versus the highest quartile was 3.0 (95% CI: 1.1-8.7) at 7-14 days, and 5.1 (95% CI: 1.2-21.9) at 3 months after the stroke. PZ levels in the convalescent sample were significantly lower than in the acute sample. In the convalescent sample, odds ratios increased with lower quartiles of protein Z level (test for trend p = 0.02). Thirty-nine patients (33%) and 32 (28%) controls were heterozygous for the G79A PZ gene polymorphism and 4 (3%) patients and 4 (4%) controls had the AA-genotype. The PZ levels were significantly lower in subjects with the AA-genotype and intermediate in heterozygote subjects. The odds ratio of ischemic stroke associated with A-allele carriers versus GG-homozygotes was 1.2 (95% CI: 0.7-2.1).

Conclusion

No association between the G79A PZ gene polymorphism and the occurrence of stroke was observed. However, low PZ levels are independently associated with an increased risk of ischemic stroke.     

Increased thrombin generation in inflammatory bowel diseases

Background

Inflammatory bowel diseases (IBD) are characterized by an increased thrombotic risk of uncertain etiology. Endogenous thrombin potential (ETP), a parameter of the thrombin generation curve, represents a new tool in the evaluation of thrombotic and bleeding disorders.

Aims

To study ETP in IBD patients and to correlate the results with clinical and biochemical features.

Methods

Seventy-four IBD patients (37 ulcerative colitis and 37 Crohn's disease) and 74 sex- and age-matched healthy individuals. ETP was measured upon activation of coagulation with small amounts of tissue factor and phospholipids in the presence or absence of thrombomodulin; results were expressed as nM thrombin·minutes.

Results

Mean±SD ETP values were significantly higher in patients (1,499 ± 454) than controls (1,261 ± 385) (p < 0.001) only when the test was performed in the presence of thrombomodulin. ETP evaluated as ratio (with/without thrombomodulin), taken as an index of hypercoagulability, was significantly higher in patients (0.69 ± 0.14) than controls (0.62 ± 0.18) (p < 0.006). Patients with increased C-reactive protein (CRP) had significantly higher mean ETP (1,721 ± 458) than those with normal CRP (1,357 ± 394) or controls (1,261 ± 385) (p < 0.001). Patients who at the time of blood sampling were classified as having a clinically active disease had ETP higher than those who were quiescent (1,655 ± 451 versus 1,388 ± 427, p < 0.001) or controls (1,261 ± 385, p < 0.001).

Conclusions

ETP measured in the presence of thrombomodulin or as ratio (with/without thrombomodulin) is increased in IBD patients, mainly in those with increased CRP or active disease. It may be considered as a candidate test for prospective studies aimed at assessing the risk of thrombosis in IBD patients.     

Patients with primary antiphospholipid antibody syndrome and without associated vascular risk factors present a normal endothelial function

Introduction

Primary antiphospholipid antibody syndrome (PAPS) is characterized by venous or arterial thrombosis and positive antiphospholipid antibodies. It is controversial whether PAPS patients have early atherosclerosis. Endothelial dysfunction is an early event in the natural history of atherosclerosis. Aim of our study was to compare endothelial function of patients with PAPS and no associated risk factors with that of age- and sex-matched controls.

Materials and Methods

Patients with PAPS, carefully selected to exclude all known risk factors for cardiovascular diseases, estrogen therapy, pregnancy, intake of drugs affecting endothelial function, vitamins or antioxidants, were included in a case-control study. Controls were age- (± 5 years) and sex-matched subjects with the same exclusion criteria but without PAPS. Flow-mediated dilation of the brachial artery and some plasmatic markers of endothelial and platelet activation were measured. Measures are expressed as mean±SEM.

Results

Twenty cases (mean age 42 ± 4.0 years, 11 females) and 39 controls (mean age 41 ± 2.9, 22 females) were studied. FMD was 5.7 ± 0.8% in cases (95% CI: 4.1 to 7.3) and 6.8 ± 0.5% (5.7 to 7.9) in controls (p = NS). Plasma von Willebrand factor was 128 ± 11.3% and 134.2 ± 16.1% in cases and controls, respectively (p = NS). Soluble P-selectin and soluble CD40L were 94.1 ± 4.9 ng/ml and 0.7 ± 0.1 ng/ml in cases and 87.7 ± 4.0 ng/ml and 1.0 ± 0.2 in controls, respectively (p = NS). In a substudy, circulating progenitor and mature endothelial cells were comparable between the two groups.

Conclusions

Endothelial function in patients with PAPS and no associated risk factors is similar to that of age- and sex- matched controls. These data suggest that the alterations leading to thrombosis in PAPS concern primarily the clotting system.     

Increased thrombin generation in women with a history of preeclampsia

Introduction

Women with a history of preeclampsia have an increased risk for cardiovascular disease in later life. We evaluated thrombogenic characteristics of women with a previous history of preeclampsia, expressed in levels of thrombin generation, number of microparticles and related to menstrual cycle and endothelial function, measured as flow-mediated dilatation.

Materials and methods

We included 18 primipara women with a history of preeclampsia and 17 healthy primipara controls, 15 (± 3) months after the index pregnancy. Thrombin generation was measured by tissue factor triggered assay, microparticle levels were measured by flow cytometry and the endothelial function was previously examined by measuring flow-mediated dilatation by high-resolution ultrasound, during follicular and luteal phases of the menstrual cycle.

Results

Women with previous preeclampsia produced more total amount of thrombin as calculated from thrombin max, thrombin potential and max slope levels p < 0.05, 0.01 and 0.01 respectively. Platelet derived microparticle levels were higher in women with a history of preeclampsia, p = 0.07. Flow-mediated dilatation was significantly decreased in comparison to healthy controls (p < 0.0001). There were no variation in levels of thrombin, microparticles and flow-mediated dilatation during the menstrual phases.

Conclusion

Women with a history of preeclampsia show signs of hypercoagulability as indicated by higher thrombin generation and higher platelet derived microparticle levels. Since these women were investigated more than one year after delivery, these results may be indicative of an increased risk of cardiovascular events later in life.     

Quality of individual INR control and the risk of stroke and bleeding events in atrial fibrillation patients: a nested case control analysis of the ACTIVE W study

Introduction

Time in therapeutic range (TTR) for international normalized ratio (INR) is an accepted quality measure of anticoagulation control in patient populations, but its usefulness for predicting stroke and bleeding in individuals is not well understood.

Materials and Methods

In a nested case control analysis among ACTIVE W study patients, cases with stroke and cases with bleeding were separately matched with controls. Several anticoagulation quality measures were compared, overall and in a time-dependent manner.

Results

32 cases with ischemic stroke and 234 cases with bleeding in the analysis were matched in a 4:1 ratio to 122 and 865 controls, respectively. Follow-up duration was 257 ± 154 days for the stroke analysis and 222 ± 146 days for the bleeding analysis. Compared with their respective controls, the study mean TTR of both stroke cases (53.9% ± 25.1 vs 63.4% ± 24.8; p = 0.055) and bleeding cases (56.2% ± 25.4 vs 63.4% ± 26.8; p < 0.001) was lower. Time below range for stroke and time above range for bleeding were only greater in the last month leading up to the event, not over the entire study period. Rather, over the entire study period bleeding cases spent more time below range than controls (26.8% ± 25.9 vs 20.8% ± 24.0; p = 0.001).

Conclusions

TTR was lower in individual AF patients with stroke or bleeding compared with matched controls in ACTIVE W. Maintaining a high TTR, with equal importance to avoid low and high INRs, is a relevant goal of individual patient treatment to prevent stroke and bleeding.     

The plasma levels of activated thrombin activatable fibrinolysis inhibitor and thrombomodulin in Behçet Disease and their association with thrombosis

Objective

To investigate the plasma levels of activated thrombin activatable fibrinolysis inhibitor (aTAFI) and thrombomodulin (TM) in Behçet disease (BD) and their relationship with thrombosis.

Methods

Plasma aTAFI and TM levels were measured by ELISA in 89 patients with BD (18 having venous thrombosis) and in 86 healthy controls.

Results

Compared with healthy controls, the BD group had significantly lower levels of aTAFI (13.49 ± 8.88 µg/ml vs. 26.76 ± 11.57 µg/ml, p < 0.0001) and significantly higher levels of TM (3.26 ± 1.85 ng/ml vs. 2.6 ± 0.69 ng/ml, p = 0.0003). Neither aTAFI, nor TM levels differed significantly between BD patients with and without thrombosis (p > 0.05). Despite a tendency to positive correlation (r = 0.37, p = 0.0004) between plasma levels of aTAFI and TM in healthy controls, there was a tendency for negative correlation (r = -0.51, p < 0.0001) between these two parameters in BD patients.

Conclusion

The plasma aTAFI and TM levels do not seem to be related with the presence of thrombosis observed in BD. Increased plasma TM levels in BD may simply reflect endothelial cell activation and dysfunction.     

Intra- and inter-rater reliability of motor unit number estimation and quantitative motor unit analysis in the upper trapezius

Objective

To collect normative data and assess the intra- and inter-rater reliability of decomposition-enhanced spike-triggered averaging (DE-STA) motor unit number estimation (MUNE) and quantitative MU analysis obtained using decomposition-based quantitative electromyography (DQEMG) in the upper trapezius (UT).

Methods

In 10 control subjects, the experimental protocol was performed twice by the same examiner, and once by a second examiner.

Results

Mean MUNE values were 339 ± 121 (rater 1a), 320 ± 131 (rater 1b), and 262 ± 115 (rater 2) MUs. Intra- and inter-rater reliability was good for maximum CMAP (ICC = 0.77 and 0.79, respectively) and moderate for MUNE (ICC = 0.69 and 0.73, respectively), with poor inter-rater reliability for mean S-MUP (ICC = 0.42). Significant differences between rater 1a and 2 were found for mean S-MUP (p = 0.014) and MUNE (p = 0.002), and moderate to good levels of reliability found for quantitative needle-detected MUP parameters.

Conclusions

Various components of the protocol may have contributed to mean S-MUP variability, and may require particular attention in a large, proximal muscle like the UT.

Significance

This study has established preliminary data using DQEMG in a novel muscle which may be relevant to study in patients with ALS.     

Haemostatic effects of phytoestrogen genistein in postmenopausal women

Introduction

Genistein is an isoflavone phytoestrogen derived from the soybean which acts as natural selective estrogen receptor modulator. Various studies have pointed out its cardioprotective role. The aim of the study was to evaluate the haemostatic effects of genistein in postmenopausal women.

Material and methods

In this double-blind placebo-controlled trial we enrolled 104 healthy postmenopausal women with osteopenia. 53 patients (mean age 54.9 ± 4.2 yr; BMI 23.4 ± 3.2 Kg/m²) received genistein (54 mg/day) and 51 patients (mean age 55.4 ± 4.3 yr; BMI 23.6 ± 3.6 Kg/m²) received an identical placebo-tablet. Both groups received a calcium and vitamin D supplement. Plasma levels of D-dimer (DD), plasminogen activator inhibitor-1 (PAI-1) and prothrombin fragment 1 + 2 (F1 + 2) were measured at baseline and after 6 and 12 months of treatment.

Results

Baseline characteristics of the two groups were similar. Compared with placebo, genistein decreased significantly DD (p < 0.001), but did not affect PAI-1 and F 1 + 2 plasma levels.

Conclusion

The results of our study do not confirm effects of genistein on activation of the haemostatic system, but on the contrary the significant decrease of DD could indicate a possible cardioprotective role of genistein in postmenopausal women.     

G-455A polymorphism of β-fibrinogen gene and the risk of premature myocardial infarction in Greece

Introduction

There are limited and controversial data regarding the impact of G-455A polymorphism of β-fibrinogen gene in the pathogenesis of premature myocardial infarction (MI). We examined whether the G-455A polymorphism of β-fibrinogen gene is associated with the development of MI ≤ 35 years of age.

Methods

We recruited 181 consecutive patients who had survived their first acute MI ≤ 35 years of age (mean age = 32.2 ± 3.4 years). The control group consisted of 129 healthy individuals matched with cases for age and sex, without a family history of premature coronary heart disease. G-455A polymorphism of β-fibrinogen was tested with polymerase chain reaction and reverse hybridization.

Results

There was a higher prevalence of carriers of the A allele (GA+AA genotype) in controls than in patients (odds ratio [OR] 0.57, 95% confidence interval [CI] 0.36 to 0.91, p = 0.02). G-455A polymorphism of β-fibrinogen gene was associated with lower risk for acute MI (OR 0.46, 95% CI 0.25 to 0.83, p = 0.01) after adjusting for major cardiovascular risk factors. Fibrinogen levels were higher in patients compared to controls [332 (292-385) vs. 311 (262-373) mg/dL, p = 0.01], but the adjusted for classical risk factors fibrinogen levels did not differ (OR 1.003, 95% CI 0.99 to 1.01, p = 0.37). Patients possessing the A allele did not differ in their fibrinogen and lipid levels compared to patients with the -455GG genotype.

Conclusions

Our data indicate that the presence of the G-455A polymorphism of β-fibrinogen gene has a “protective effect” against the development of non-fatal acute MI ≤ 35 years of age in Greece.     

Endothelial, platelet, and tissue factor-bearing microparticles in cancer patients with and without venous thromboembolism

Background

Cancer is a prothrombotic state, with an increased prevalence of venous thromboembolism (VTE). Microparticles (MPs) are sub-micron-sized vesicles derived from activated or apoptotic cells that may play a role in VTE, although evidence of this association is still limited.

Objectives

To evaluate the hypothesis that elevated numbers of endothelial (EMPs), platelets (PMPs), and Tissue Factor-bearing MPs (TF⁺MPs) in plasma may contribute to cancer-associated thrombosis.

Patients/Methods

EMPs, PMPs and TF⁺MPs plasma levels were measured in 90 consecutive patients (cases) referred to our Department (30 with a first episode of unprovoked VTE; 30 with active cancer; 30 with a diagnosis of acute VTE associated with active cancer), and in a group of 90 healthy subjects (controls). MPs analyses were performed by flow-cytometry (Cytomics FC500).

Results

Cases showed statistically significant higher (mean ± SD) circulating EMPs and PMPs plasma levels (920 ± 341 and 1221 ± 413 MP/μL, respectively) than controls (299 ± 102 and 495 ± 241 MP/μL; p < 0.005). Moreover cancer patients (with and without VTE) showed higher (mean ± SD) TF⁺MPs (927 ± 415 MPs/μL) than controls (204 ± 112 MPs/μL; p < 0.001). The subgroup of cancer patients plus VTE showed statistically significant higher TF⁺MPs plasma levels (1019 ± 656 MPs/μL) than cancer patients without VTE (755 ± 391 MPs/μL, p = 0.002). Multivariate analysis failed to show a significant association between elevated TF⁺MPs and VTE in cancer patients.

Conclusions

Our results suggest that MPs might be an important intermediate in the cascade of cellular injury and vascular dysfunctions underlying the process of thrombosis, particularly in cancer. Further clinical investigations are needed to confirm the precise role of MPs in predicting hypercoagulable state in patients with cancer.     

Risk of early recurrent fetal loss and levels of thrombin-activatable fibrinolysis inhibitor

Introduction

Though thrombin-activatable fibrinolysis inhibitor (TAFI) may contribute to hypercoagulability during pregnancy, limited data are available on the role of TAFI in women with recurrent fetal loss.

Material/Methods

We performed a case-control study aimed at evaluating any possible association between TAFI levels and early recurrent fetal loss (≥ 3, or 2 with at least one normal fetal karyotype, before the 10th week of gestation). 140 women with early recurrent fetal loss and 140 age-matched healthy controls with at least one normal pregnancy were included. The number of miscarriages was 2.59 and occurred at gestational age 6.89 weeks. TAFI levels were determined by a chromogenic assay measuring total potential activatable TAFI.

Results

TAFI levels were significantly lower in early recurrent fetal loss women (12.2 ± 2.3 μg/ml vs 13.2 ± 2.6 μg/ml in healthy controls, p = 0.001). ORs of early recurrent fetal loss (crude and adjusted for possible confounding variables) were calculated after stratification of TAFI levels into quartiles. 25/140 (17.8%) early recurrent fetal loss women had TAFI levels above 14.0 μg/ml (4th quartile) vs 44/140 (31.3%) in healthy women (p = 0.014). Crude and adjusted ORs of early recurrent fetal loss in women with TAFI levels in the 4th quartile vs those in the reference category (1st quartile = below 11.0 μg/ml) were 0.42 (95%CI: 0.22-0.82) and 0.39 (95%CI: 0.19-0.80), respectively.

Conclusions

Our study provides evidence that high TAFI levels are associated with reduced risk of early recurrent fetal loss. Further studies are needed to better understand the actual role of TAFI in recurrent fetal loss.     

The impact of platelet membrane glycoprotein Ib alpha and Ia/IIa polymorphisms on the risk of thrombosis in the antiphospholipid syndrome

Background

Pathogenesis of thrombus formation in antiphospholipid syndrome (APS) is not clear. Platelet membrane glycoprotein (GP) receptors play important roles in development of thrombosis.

Objectives

We investigated the association between development of thrombosis in APS and polymorphisms of GPIb alpha variable number of tandem repeats (VNTR), Kozak, and GPIa C807T.Patients/MethodsSixty patients with APS (30 with proven thrombosis and 30 without thrombosis) and 63 controls were included. Presence of GPIa C807T polymorphism was determined with real-time PCR and GPIb alpha Kozak and VNTR polymorphisms by conventional PCR.

Results

Frequency of C807T TT genotype was significantly higher in APS with thrombosis than APS without thrombosis (p = 0.023) and also in APS with multiple thrombi compared to APS without thrombi (p = 0.023). Frequency of Kozak TC genotype was higher in APS with arterial thrombosis compared to APS with venous thrombosis, controls, and APS without thrombosis (p = 0.03, p = 0.0007, and p = 0.0024 respectively). D allele frequency and D allele carrier state for VNTR were significantly less in APS than controls (p = 0.0018 and p = 0.0046 respectively).

Conclusions

C807T TT genotype may confer a risk for thrombosis and Kozak TC genotype for arterial thrombosis. D allele of VNTR may protect from APS. No patients with C807T TT or Kozak TC genotypes carried the protective DD genotype of VNTR. These polymorphisms may increase risk for both arterial and venous thrombosis. The utility of prophylaxis with anti-platelet drugs in at least a subgroup of APS patients should be investigated with clinical trials.     

Tissue factor-induced Thrombin Generation in the Fasting and Postprandial State among Elderly Survivors of Myocardial Infarction

Introduction

Tissue factor (TF)-induced thrombin generation (TG) ex vivo has been suggested to be an important method to assess thrombotic risk. No studies have investigated the impact of postprandial lipemia on TF-induced TG. Since myocardial infarction (MI) is associated with elevated postprandial levels of triglycerides, we hypothesized a differential impact of postprandial lipemia on coagulation activation in MI-patients and healthy controls.

Material and Methods

Elderly survivors of acute MI (n = 44) and healthy age-and sex matched controls (n = 43) underwent a fat tolerance test (1 gram per kg body weight) to assess coagulation activation during postprandial lipemia.

Results

The incremental area under the curve (AUCi) for serum triglycerides was higher in MI-patients than in healthy age-and sex matched controls (5.64 ± 0.52 mmol/L?h and 3.94 ± 0.39 mmol/L?h, p = 0.012) during the postprandial phase. Subsequent endogenous activation of coagulation, assessed by FVIIa and thrombin generation (F1 + 2), was similar among groups and not related to levels of triglycerides during the postprandial phase. Healthy individuals had a gradual decline in TF-induced thrombin generation ex vivo, assessed by endogenous thrombin potential (ETP) (AUCi = - 542.4 ± 71.4 nM?min?h, p < 0.001), whereas MI-patients retained their ETP (AUCi = 127.4 ± 89.0 nM?min?h, p = 0.47) in plasma during the postprandial phase (p for group difference = 0.005).

Conclusions

MI-patients had elevated postprandial lipemia and retained their ability for TF-induced TG in plasma ex vivo in the postprandial phase, whereas the capacity gradually decreased in healthy individuals. Further studies are warranted to reveal underlying mechanism(s) and clinical implications.     

Shared impairment in associative learning in schizophrenia and bipolar disorder

Background

Schizophrenia (SCZ) and bipolar disorder (BD) share some cognitive commonalities. However, the role of associative learning, which is a cornerstone of human cognition mainly relying on hippocampus, has been under-investigated. We assessed behavioral performance during associative learning in a group of SCZ, BD and healthy controls (HC).

Methods

Nineteen patients with SCZ (36 ± 8.1 years; 13 males, 6 females; all Caucasians), 14 patients with BD (41 ± 9.6 years; 5 males, 9 females; all Caucasians) and 45 HC (27.7 ± 6.9 years; 18 males, 27 females; all Caucasians) were studied. Learning was assessed using an established object-location paired-associative learning paradigm. Subjects learned associations between nine equi-familiar common objects and locations in a nine-location grid. Performance data were analyzed in a repeated measures analysis of variance with time (repeated) and group as factors.

Results

Learning curves (performance = 1−e^−k?time) fitted to average performance data in the three groups revealed lower learning rates in SCZ and BD (k = 0.17 and k = 0.34) than HC (k = 0.78). Significant effects of group (F = 11.05, p < 0.001) and time (F = 122.06, p < 0.001) on learning performance were observed.

Conclusions

Our study showed that associative learning is impaired in both SCZ and BD, being potentially not affected by medication. Future studies should investigate the neural substrates of learning deficits in SCZ and BD, particularly focusing on hippocampus function and glutamatergic transmission.     

Male mice have increased thrombotic potential: sex differences in a mouse model of venous thrombosis

Introduction

Our objectives were to characterize sex differences during venous thrombosis, using the electrolytic inferior vena cava model of the disease.

Materials and methods

Male and female C57BL/6 mice (6-8 weeks) underwent inferior vena cava thrombosis. Time points included 6 hours, day 2, day 6, and day 14 post surgery, along with surgically naïve true controls and surgical shams. Analyses included thrombus weight, vein wall morphometrics, vein wall protein and gene expression for P-selectin, interleukin-1β, and tumor necrosis factor-α; hematology, soluble P-selectin, and plasma microparticle tissue factor activity assays.

Results

Male venous thrombi were significantly larger than females at days 2 (13.1 ± 1.0 vs. 6.8 ± 0.5 × 10^-3 grams, p < 0.01), 6 (10.4 ± 0.8 vs. 5.4 ± 0.5 × 10^-3 grams, p < 0.01) and 14 (6.3 ± 0.5 vs. 4.1 ± 0.3 × 10^-3 grams, p < 0.01). Both male and female mice exhibited significantly increased vein wall P-selectin at 6 hours, vs. true controls (p < 0.05). Males had increased vein wall interleukin-1β, versus females, at 6 hours (180.926 ± 24.596 vs. 60.417 ± 10.478 pg/mL, p < 0.05) and day 6 (76.966 ± 13.081 vs. 33.834 ± 4.198 pg/mL, p < 0.01). Males showed decreased tumor necrosis factor-α expression (-66 %) at 6 hours. Females had increased tumor necrosis factor-α expression at 6 hours (+ 541%) and day 6 (+ 539%). Both sexes demonstrated decreased peripheral platelets at 6 hours (p < 0.05), coinciding with thrombogenesis. Plasma P-selectin increased in both sexes, versus controls, through day 6 (p < 0.05).

Conclusions

Males had significantly larger venous thrombi than females. Sex differences in vascular anatomy and response to inflammation may influence thrombus formation in our mouse thrombosis model.     

Circulating microparticles and risk of venous thromboembolism

Introduction

Circulating microparticles (MPs) may trigger a hypercoagulable state, leading to thrombotic complications. Data on their association with venous thromboembolism (VTE) are few and inconsistent.

Materials and methods

To investigate whether or not high levels of MPs are associated with an increased risk of VTE, we carried out a case-control study on 186 patients with a first, objectively diagnosed, episode of VTE and 418 healthy controls. Plasma levels of circulating MPs were measured by flow cytometry.

Results

Patients had higher median plasma levels of total MPs than controls (2184 per μL vs 1769 per μL, p < 0.0001). The risk of VTE increased progressively with increasing MPs, with a linear dose-response effect in the log odds. Individuals with MPs above the 90th percentile of the controls’ distribution (P₉₀ = 3263 per μL) had a 5-fold increased risk of VTE than those with MPs below the 10th percentile of controls (P₁₀ = 913 per μL), independently of sex, age, body mass index, thrombophilia, and plasma factor VIII levels [adjusted odds ratio: 5.30 (95%CI: 2.05-13.7)]. Using the 95th percentile of controls as cut-off (P₉₅ = 4120 per μL), the adjusted odds ratio was 2.20 (1.01-4.79) for individuals with MPs > P₉₅ compared with those having MPs ≤ P₉₅. After exclusion of individuals with antiphospholipid antibodies and hyperhomocysteinemia, the interaction between MPs > P₉₅ and thrombophilia increased the VTE risk from 1.63 (0.60-4.50) to 6.09 (1.03-36.1).

Conclusions

High levels of circulating MPs are a possible independent risk factor for VTE.     

A case-control study provides evidence of association for a common SNP rs974819 in PDGFD to coronary heart disease and suggests a sex-dependent effect

Introduction

Peden et al. have revealed a significant association between four new risk loci and coronary heart disease (CHD) in Europeans and South Asians. The goal of this study is to evaluate the contribution of these genetic loci to CHD risk in Han Chinese.

Methods

We recruited 161 CHD patients and 112 controls proved by angiography originated from Ningbo in the Eastern China, and performed a case-control association study of the four significant SNPs.

Results

Among the four tested SNPs, we found a significant association of rs974819 in PDGFD gene with CHD (allele p = 0.04; OR = 1.45, 95% CI = 1.02 - 2.08) and the allele A/G of rs974819 shows significant difference in females (allele p = 0.04; OR = 1.83, 95% CI = 1.01 - 3.31). A further meta-analysis showed that rs974819 of PDGFD gene was significantly associated with an increasing risk of CHD (OR = 1.08, 95% CI = 1.05 - 1.11) in both Europeans and South Asians including Han Chinese.

Conclusions

Our findings suggests that rs974819 of PDGFD is also a CHD risk factor in Han Chinese. In addition, it presents a sex-dependent genetic effect.     

Persistent high factor VIII activity leading to increased thrombin generation - a prospective cohort study

Introduction

A persistently elevated level of factor VIII (FVIII) is an independent risk factor for venous thromboembolism (VTE). Although the pathophysiology of VTE is unclear, the involvement of thrombin generation (TG) has been postulated. Consequently this study was designed to (i) investigate the relationships between FVIII, Thrombin generation test (TGT) parameters and D-dimer in VTE patients, (ii) determine whether elevated levels of FVIII and increased TG in these patients are transient or sustained.

Patients and Methods

After an initial period of anticoagulation had been completed 91 VTE patients and 52 healthy controls were recruited. FVIII levels were determined by one-stage clotting (FVIII:C) and chromogenic (FVIII:Ch) assays. The potential to generate thrombin was measured using the Calibrated Automated Thrombogram (CAT) and D-Dimer was by immuno-turbidometric assay.

Results

Patients' FVIII:C levels and FVIII:Ch, exhibited good agreement (rs = 0.94; p < 0.0001), although FVIII:C exhibited a mean bias of -6%. FVIII:Ch show a significant correlation with TGT Peak Thrombin (rs = 0.30; p = 0.004) and Peak Thrombin was found to be significantly higher (p = 0.04) in patients with FVIII > 200 iu/dL. Furthermore elevated levels of FVIII and increased thrombin generation parameters appeared to be consistent over time.

Conclusion

Our data suggests that high FVIII leading to increased TG confers a significant risk of recurrent VTE and therefore we speculate that these patients may benefit from prolonged anticoagulation therapy.     

Endogenous thrombin potential (ETP) in plasma from patients with AMI during antithrombotic treatment

Background

The beneficial impact of warfarin in preventing new events after AMI is well established. Decrease in thrombin generation seems to be the key element in anticoagulant treatment.

Objectives

The aims were to investigate the effect of warfarin and platelet inhibition on thrombin generation, assessed by the endogenous thrombin potential (ETP), and study the relation between coagulation parameters and ETP in patients with AMI.

Patients/Methods

In the present sub-study of the WARIS II trial, patients with AMI were randomly assigned to treatment with aspirin 160 mg/d (n = 57), aspirin 75 mg/d and warfarin (INR 2.0-2.5) (n = 68) or warfarin (INR 2.8-4.2) (n = 61). Fasting blood samples were collected from patients at discharge from hospital and after 6 weeks treatment.

Results

Correlation analyses showed that both ETP and peak thrombin levels were significantly correlated with Factor VII Ag (r = 0.38 and 0.36 respectively, p < 0.01 for both) and with F1+2 (r = 0.26 and 0.23 respectively, p = 0.01 for both) at baseline. Antithrombotic treatment for 6 weeks caused a highly significant inhibition of ETP in patients treated with warfarin (− 28% ± 5%, p < 0.001), and patients treated with aspirin/warfarin (− 24% ± 8%, p = 0.04). Similarly, peak thrombin levels were reduced in patients treated with warfarin (− 18% ± 7%, p = 0.049) and aspirin/warfarin (− 19% ± 5%, p = 0.029), whereas an increase (12% ± 4%, p = 0.029) occurred during aspirin treatment alone. F1+2 levels decreased by 64% and 58% in the warfarin and aspirin/warfarin groups, respectively (p = 0.001 for both).

Conclusions

In patients with AMI, warfarin significantly reduced the endogenous thrombin generation and the potential to generate thrombin in plasma ex vivo, whereas aspirin alone had no effect on thrombin generation in vivo or ex vivo, assessed by ETP.     

Genetic determinants of response to aspirin: appraisal of 4 candidate genes

Introduction

Intersubject variability in platelet response to aspirin could be related to genetic factors that regulate platelet enzymes or receptors. This study evaluates the impact of the selected polymorphisms in the COX-1 gene, the CYP5A1 gene, the P2RY1 receptor gene, and the GPIIbIIIa receptor gene on platelet response to aspirin and risk of suffering from major adverse cardiovascular and cerebrovascular events (MACCE).

Materials and methods

192 Caucasian patients with stable coronary artery disease treated with daily aspirin were recruited and followed for 3 years. Platelet aggregation was measured by light transmission aggregometry with arachidonic acid (1.6 mM) and adenosine diphosphate (5, 10 or 20 μM) used as agonists. Genotyping was performed by standard PCR methods.

Results

Arachidonic acid-induced platelet aggregation was unaffected by the COX-1 22C/T and by the Pl^A1/A2 polymorphisms. However, carriers of the 1622 G/G genotype of the P2RY1 gene had significantly higher levels of arachidonic acid-induced platelet aggregation compared with non-carriers (AA 2.0%, AG 2.0% vs. GG 9.0%, p = 0.047). Carrying the 1622 G/G genotype increased the risk of inadequate platelet response to aspirin, defined as arachidonic acid-induced aggregation ≥ 20%, by a factor of 8.5 (1.4 - 53.3, p = 0.022) and the risk of 3-year MACCE by a factor of 7 (1.4 - 34.7, p = 0.017).

Conclusion

The 1622A/G mutation of the P2RY1 gene could contribute to inadequate platelet response to aspirin and is associated with an increased risk of suffering from MACCE.