Association between fibrinogen and fibrinogen γ' and atherosclerotic plaque morphology and composition in symptomatic carotid artery stenosis: Plaque-At-RISK study

INTRODUCTION

Von Willebrand Factor (VWF), ADAMTS13, fibrinogen and fibrinogen γ' are associated with an increased risk of ischemic stroke. Carotid atherosclerosis is an important risk factor for ischemic stroke. Characteristics of the vulnerable plaque; intraplaque hemorrhage (IPH), plaque ulceration and lipid-rich necrotic core (LRNC) can be visualized with imaging techniques. Since atherosclerosis might attribute to the association between coagulation factors and ischemic stroke risk, the aim of this study is to investigate the association between coagulation factors and atherosclerotic plaque characteristics in more detail.

MATERIALS AND METHODS

In 182 patients of the Plaque-At-RISK study (prospective multicenter cohort study) with a recent transient ischemic attack (TIA) or ischemic stroke and a symptomatic mild-to-moderate carotid artery stenosis, we measured VWF antigen (VWF:Ag), ADAMTS13 activity, fibrinogen (Clauss), and fibrinogen γ'. Presence of plaque ulceration, IPH volume and LRNC volume were determined by Multidetector-Row Computed Tomography (MDCTA, n = 160) and Magnetic Resonance Imaging (MRI, n = 172). Linear regression analysis was used to assess the association between imaging biomarkers and coagulation factors.

RESULTS

VWF:Ag or ADAMTS13 levels were not significantly associated with plaque ulceration, IPH and LRNC. We found an inverse association between fibrinogen and fibrinogen γ' and IPH volume (B = -23.40 mm³/g/L, p = 0.01 and B = -161.73 mm³/g/L, p = 0.01) and between fibrinogen and fibrinogen γ' and LRNC volume (B = -38.89 mm³ g/L, p < 0.01 and B = -227.06 mm³ g/L, p = 0.01). Additional adjustments for C-reactive protein (CRP) did not change the results.

CONCLUSIONS

Fibrinogen and fibrinogen γ' are inversely associated with IPH volume and LRNC volume, independent of inflammation.

CLINICAL TRIAL REGISTRATION

clinicaltrials.govNCT01208025.

Clinically relevant differences between assays for von Willebrand factor activity

Essentials It is unclear whether there are differences between von Willebrand factor (VWF) activity assays. We compared the four most used VWF activity assays in 661 von Willebrand disease (VWD) patients. All assays correlated excellently, but a discrepant classification was seen in 20% of patients. Differences between VWF activity assays have a large impact on the classification of VWD. SUMMARY: Background Measuring the ability of von Willebrand factor (VWF) to bind to platelets is crucial for the diagnosis and classification of von Willebrand disease (VWD). Several assays that measure this VWF activity using different principles are available, but the clinical relevance of different assay principles is unclear. Objective To compare the four most widely used VWF activity assays in a large VWD patient population. Methods We measured VWF:RCo (ristocetin to activate VWF + whole platelets), VWF:GPIbR (ristocetin + platelet glycoprotein Ib receptor [GPIb] fragments), VWF:GPIbM (gain-of-function GPIb fragments that bind VWF spontaneously without ristocetin) and VWF:Ab (monoclonal antibody directed against the GPIb binding epitope of VWF to mimic platelets) in 661 VWD patients from the nationwide 'Willebrand in the Netherlands' (WiN) Study. Results All assays correlated excellently (Pearson r > 0.9), but discrepant results led to a different classification for up to one-fifth of VWD patients. VWF:RCo was not sensitive enough to classify 18% of patients and misclassified half of genotypic 2B VWD patients, especially those with p.Arg1306Trp. VWF:GPIbR was more sensitive, accurately classified the vast majority of patients, and was unaffected by the p.Asp1472His variant that causes artificially low VWF:RCo. VWF:GPIbM was the most precise assay but misclassified over a quarter of genotypic 2A, 2B and 3 patients. VWF:Ab, often not considered an actual VWF activity assay, performed at least equally to the other assays with regard to accurate VWD classification. Conclusion Although the different VWF activity assays are often considered similar, differences between assays have a large impact on the classification of VWD.

Seasonal Variation in Fibrinogen in the Rotterdam Study

As evidence accumulates to implicate fibrinogen as a risk indicator for cardiovascular disease, it is of interest to study its seasonal variation. A population based cross-sectional study was performed among participants of the Rotterdam Study, a cohort of 7,983 men and women, aged 55 years and over. Fibrinogen levels were measured by the prothrombin time derived method in the first 2,325 participants of the study. Fibrinogen levels were considerably higher in winter. The seasonal difference was 0.34 g/1 (95% confidence interval 0.29,0.39) and was more pronounced in subjects aged 75 years and over than in subjects aged 55 to 75 years, 0.43 g/1 (0.34,0.52) and 0.29 g/1 (0.24,0.35), respectively. Additional adjustment for body mass index, systolic and diastolic blood pressure, and total and HDL cholesterol did not materially change the findings. After adjustment for seasons, outdoor temperature was not associated with fibrinogen. Adjustment for outdoor temperature did not change the seasonal variation of fibrinogen, seasonal difference 0.31 g/1 (0.24, 0.37). In conclusion, fibrinogen levels are highest in Winter. The seasonal variation of fibrinogen is more pronounced in the elderly. Outdoor temperature does not seem to play a role in the seasonal variation of fibrinogen. Seasonal variation of fibrinogen may partly explain the increased cardiovascular disease mortality in Winter.

Modulation of Plasma Fibrinogen Levels by Ciprofibrate and Gemfibrozil in Primary Hyperlipidaemia

An elevated plasma fibrinogen level is increasingly accepted as an independent risk indicator of cardiovascular disease. This has enhanced the interest in identifying agents that can normalize elevated plasma fibrinogen levels. One group of agents with this capacity are the fibric acid derivatives, e.g. ciprofibrate and gemfibrozil.

We studied fibrinogen levels after 12 weeks of treatment with ciprofibrate (n = 48) and gemfibrozil (n = 51) in hypercholesterolemic patients. The correlation of the decrease in fibrinogen with lipid lowering and the contribution of the acute phase and genetic polymorphisms to this decrease were also evaluated.

After 12 weeks of treatment, the fibrinogen levels were significantly decreased (p<0.0005) with both drugs, although the decrease in the ciprofibrate group (mean 3.4 g/1 pre-treatment to 2.4 g/1 after 12 weeks) was larger than in the gemfibrozil group (mean 3.4 g/1 to 3.0 g/1.). The lipid lowering effect was comparable for the two drugs but there was no correlation for either ciprofibrate or gemfibrozil between the lipid lowering and the magnitude or the velocity of the fibrinogen lowering effect. An attenuation of the major regulatory mechanism of plasma fibrinogen levels, the acute phase reaction, was invoked as the underlying mechanism. However, pre-treatment C-reactive protein levels were not increased and did not change after treatment. Moreover, no effects of the polymorphisms of the fibrinogen β-gene on the decrease of the plasma fibrinogen levels were observed. This suggests that a new, as yet unknown, mechanism is involved in fibrinogen lowering by fibrates.

Monitoring of treatment with vitamin K antagonists: recombinant thromboplastins are more sensitive to factor VII than tissue-extract thromboplastins

Essentials Differences in sensitivity to factor VII (FVII) have been suggested between thromboplastins. FVII-induced International Normalized Ratio (INR) changes differ between commercial reagents. Recombinant human thromboplastins are more sensitive to FVII than tissue-extract thromboplastins. Thromboplastin choice may affect FVII-mediated INR stability.

SUMMARY

Background Differences regarding sensitivity to factor VII have been suggested for recombinant human and tissue-extract thromboplastins used for International Normalized Ratio (INR) measurement, but the evidence is scarce. Differences in FVII sensitivity are clinically relevant, as they can affect INR stability during treatment with vitamin K antagonists (VKAs). Objectives To determine whether commercial thromboplastins react differently to changes in FVII. Methods We studied the effect of addition of FVII on the INR in plasma by using three tissue-extract (Neoplastin C1+, Hepato Quick, and Thromborel S) and three recombinant human (Recombiplastin 2G, Innovin, and CoaguChek XS) thromboplastins. Three different concentrations of purified human FVII (0.006, 0.012 and 0.062 μg mL-1 plasma), or buffer, were added to five certified pooled plasmas of patients using VKAs (INR of 1.5-3.5). Changes in FVII activity were measured with two bioassays (Neoplastin and Recombiplastin), and relative INR changes were compared between reagents. Results After addition of 0.062 μg mL-1 FVII, FVII activity in the pooled plasmas increased by approximately 20% (Neoplastin) or 32% (Recombiplastin) relative to the activity in pooled normal plasma. All thromboplastins showed dose-dependent INR decreases. The relative INR change in the pooled plasmas significantly differed between the six thromboplastins. No differences were observed among recombinant or tissue-extract thromboplastins. Pooled results indicated that the FVII-induced INR change was greater for recombinant than for tissue-extract thromboplastins. Conclusions Differences regarding FVII sensitivity exist between various thromboplastins used for VKA monitoring. Recombinant human thromboplastins are more sensitive to FVII than tissue-extract thromboplastins. Therefore, thromboplastin choice may affect FVII-mediated INR stability.

Low ADAMTS-13 activity and the risk of coronary heart disease - a prospective cohort study: the Rotterdam Study

Essentials An association between ADAMTS-13 and coronary heart disease (CHD) has been suggested. 5688 participants ≥ 55 years from the Rotterdam Study without a history of CHD were included. Over a median follow-up time of 9.7 years, 456 individuals suffered from CHD. Low ADAMTS-13 activity was associated with an increased CHD risk.

SUMMARY

Background The metalloprotease ADAMTS-13 cleaves high-molecular-weight von Willebrand factor multimers into smaller, less procoagulant forms. Low ADAMTS-13 activity is associated with an increased risk of ischemic stroke but its pathogenic role in coronary heart disease (CHD) is unclear. Objectives We aimed to determine the association between ADAMTS-13 activity and the risk of CHD in a large prospective population-based cohort study. Methods A total of 5688 participants of the Rotterdam Study, a population-based cohort study involving individuals aged ≥ 55 years without a history of CHD, were included. ADAMTS-13 activity was measured by the FRETS-VWF73 assay and VWF:Ag levels by ELISA. We assessed the association between ADAMTS-13 activity, VWF:Ag levels and CHD using Cox proportional hazard regression analysis, adjusting for cardiovascular risk factors. Results Over a median follow-up time of 9.7 years, 456 individuals suffered from CHD. A low ADAMTS-13 activity (quartile 1) was associated with an increased CHD risk (HR 1.42, 95% CI 1.07-1.89) compared with the reference highest quartile. Conclusions Low ADAMTS-13 activity is associated with an increased risk of CHD in the elderly, independently of VWF and established cardiovascular risk factors.

Impact of point-of-care international normalized ratio monitoring on quality of treatment with vitamin K antagonists in non-self-monitoring patients: a cohort study

BACKGROUND

Point-of-care (POC) international normalized ratio (INR) monitoring by healthcare professionals could eliminate the need for venous blood sampling in non-self-monitoring (NSM) patients on vitamin K antagonists (VKA). However, few studies have investigated the impact of POC INR monitoring on the quality of treatment in these patients and real-world data on this issue are lacking.

OBJECTIVES

To investigate the safety, efficacy and quality of anticoagulant control during POC INR monitoring as compared with laboratory INR monitoring in NSM patients.

METHODS

We performed a retrospective cohort study using data from the anticoagulation clinic of the Star-Medical Diagnostic Center (Rotterdam, the Netherlands). Patients who received treatment with VKA between 29 May 2012 and 29 May 2014 were eligible. Percentage of time in therapeutic range (TTR) and incidence rates of major clinical events (all-cause mortality, hospitalization, major bleeding and ischemic stroke) were compared for the year before and year after introduction of POC monitoring. Cox proportional hazard models were used to estimate hazard ratios and 95% confidence intervals for major clinical events between exposure groups.

RESULTS

In total, 1973 patients during the 1-year laboratory-monitoring observation period and 1959 patients during the 1-year POC-monitoring observation period were included. Median TTR was significantly lower during POC monitoring (77.9%; 95% CI, 67.2-87.4) than during laboratory INR monitoring (81.0%; 95% CI, 71.1-90.5). Adjusted hazard ratios for major clinical events were all around unity.

CONCLUSIONS

Although associated with lower TTR, POC INR monitoring is a safe and effective alternative to laboratory INR monitoring in NSM patients on VKA.

Side effects of desmopressin in patients with bleeding disorders

INTRODUCTION

Desmopressin is frequently used in patients with bleeding disorders because of its prohaemostatic effects. In recent years desmopressin use increased due to reported high incidence of inhibitors in mild haemophilia after clotting factor infusion and the rising costs of clotting factor concentrates. The safety and frequency of side effects have hardly been assessed in well-designed studies.

AIM

We therefore prospectively evaluated side effects of desmopressin in a large unselected cohort of bleeding disorder patients, who received a desmopressin test dose.

METHODS

Blood was drawn prior to, one, three, six and 24 h after desmopressin. Primary outcome was change in serum sodium, haematocrit, serum- and urine osmolality, body weight and vital signs. Self-reported side effects were evaluated as secondary outcome.

RESULTS

In total, 108 patients were included, median age 30 years, the majority of whom had von Willebrand disease type 1 (76%). A significant change in water balance parameters was observed. Four patients (4%) had hyponatraemia (≤135 mmol L(-1) ) after 24 h but no severe hyponatraemia occurred (≤125 mmol L(-1) ). After infusion, 41 (38%) patients were hypotensive (≤90 mmHg SBP and/or ≤60 mmHg DBP) and 10 (9%) presented with tachycardia (>100 min(-1) ). However, none of these effects sustained at 24 h. Infusion was discontinued in one patient because of tachycardia, nausea and malaise. Self-reported side effects included: headache, fatigue, flush and dizziness.

CONCLUSION

Observed side effects correspond with the known antidiuretic and vasomotor effects of desmopressin. Changes in parameters were temporary and not clinically relevant. In conclusion, our study supports desmopressin use as a safe treatment option in patients with various bleeding disorders.

CLEC4M and STXBP5 gene variations contribute to von Willebrand factor level variation in von Willebrand disease

BACKGROUND

von Willebrand factor (VWF) levels in healthy individuals are influenced by variations in genetic loci other than the VWF gene, whose contribution to VWF levels in patients with von Willebrand disease (VWD) is largely unknown.

OBJECTIVES

To investigate the association between single-nucleotide polymorphisms (SNPs), VWF levels, and bleeding phenotype.

PATIENTS/METHODS

In 364 type 1 VWD and 240 type 2 VWD patients from the nationwide cross-sectional 'Willebrand in The Netherlands' (WiN) study, we studied the association between eight SNPs in STXBP5, SCARA5, ABO, VWF, STAB2, STX2, TC2N, and CLEC4M, and VWF antigen (VWF:Ag), VWF activity (VWF:Act), and bleeding phenotype as assessed with the Tosetto bleeding score.

RESULTS

In type 1 patients, STXBP5 was associated with a lower VWF:Ag level (adjusted difference of -3.0 IU dL(-1) per allele; 95% confidence interval [CI] -6.0 to 0.1) and CLEC4M with both a lower VWF:Ag level (-4.3 IU dL(-1) per allele; 95% CI -7.9 to -0.6) and lower VWF:Act (-5.7 IU dL(-1) per allele; 95% CI -10.9 to -0.5). In type 2 patients, none of the SNPs was associated with VWF levels. None of the genetic variants was associated with bleeding score.

CONCLUSIONS

Genetic variations in STXBP5 and CLEC4M are associated with VWF level variation in type 1 VWD, but not in type 2 VWD. This study increases our understanding of the pathophysiology of VWD, and provides a further indication of the involvement of STXBP5 and CLEC4M in determining VWF levels in VWD.

Full regeneration of segmental bone defects using porous titanium implants loaded with BMP-2 containing fibrin gels

Regeneration of load-bearing segmental bone defects is a major challenge in trauma and orthopaedic surgery. The ideal bone graft substitute is a biomaterial that provides immediate mechanical stability, while stimulating bone regeneration to completely bridge defects over a short period. Therefore, selective laser melted porous titanium, designed and fine-tuned to tolerate full load-bearing, was filled with a physiologically concentrated fibrin gel loaded with bone morphogenetic protein-2 (BMP-2). This biomaterial was used to graft critical-sized segmental femoral bone defects in rats. As a control, porous titanium implants were either left empty or filled with a fibrin gels without BMP-2. We evaluated bone regeneration, bone quality and mechanical strength of grafted femora using in vivo and ex vivo µCT scanning, histology, and torsion testing. This biomaterial completely regenerated and bridged the critical-sized bone defects within eight weeks. After twelve weeks, femora were anatomically re-shaped and revealed open medullary cavities. More importantly, new bone was formed throughout the entire porous titanium implants and grafted femora regained more than their innate mechanical stability: torsional strength exceeded twice their original strength. In conclusion, combining porous titanium implants with a physiologically concentrated fibrin gels loaded with BMP-2 improved bone regeneration in load-bearing segmental defects. This material combination now awaits its evaluation in larger animal models to show its suitability for grafting load-bearing defects in trauma and orthopaedic surgery.

von Willebrand factor plasma levels, genetic variations and coronary heart disease in an older population

BACKGROUND

High von Willebrand factor (VWF) levels are associated with an increased risk of coronary heart disease (CHD). However, it remains unclear whether VWF is causally related to the occurrence of CHD or primarily mirrors endothelial dysfunction, which predisposes to atherosclerosis and subsequent CHD.

OBJECTIVES

Because VWF is largely determined by genetic factors, we investigated whether VWF antigen levels (VWF:Ag) and the risk of CHD are affected by common variations in the VWF gene.

METHODS

We included 7002 participants (≥ 55 years) from the large prospective population-based Rotterdam Study in the discovery cohort. The extension cohort of the Rotterdam Study, consisting of 3011 participants, was used as a replication cohort. We determined VWF:Ag levels and genotype data of 38 single-nucleotide polymorphisms (SNPs) in VWF. Subsequently, hazard ratios for CHD were calculated and genetic analyses were performed to assess the relationship between SNPs, VWF:Ag levels and CHD risk.

RESULTS

We identified and replicated three SNPs that were associated with VWF:Ag: rs216321 (β = 0.10 [95% confidence interval, CI, 0.06;0.13]) (Ala852Gln), rs1063856 (β = 0.05 [95% CI 0.03;0.07]) (Thr789Ala) and rs2283333 (β = 0.09 [95% CI 0.05;0.21]) (intron 15). However, genetic polymorphisms in the VWF gene were not associated with the risk of CHD.

CONCLUSIONS

In this study we have shown that genetic variations in VWF strongly affect VWF plasma levels, but are not associated with the risk of CHD. Our findings therefore do not support a strong causal relationship between VWF and CHD in elderly individuals of ≥ 55 years, but suggest that VWF is primarily a marker of CHD.

The hypercoagulable state in Cushing's disease is associated with increased levels of procoagulant factors and impaired fibrinolysis, but is not reversible after short-term biochemical remission induced by medical therapy

CONTEXT

Cushing's disease (CD) is accompanied by an increased risk of venous thromboembolism. Surgery is the primary treatment of CD.

OBJECTIVE

The aim of the study was to compare hemostatic parameters between patients with CD and controls and to evaluate the effect of medical treatment of CD on hemostasis.

DESIGN AND SETTING

During 80 d, stepwise medical treatment was applied with the somatostatin analog pasireotide, the dopamine agonist cabergoline, and ketoconazole, which suppresses adrenocortical steroidogenesis, at four university medical centers in The Netherlands.

PATIENTS

Seventeen patients with de novo, residual, or recurrent CD were included.

MAIN OUTCOME MEASURES

We measured urinary free cortisol and parameters of coagulation and fibrinolysis.

RESULTS

Patients with CD had significantly higher body mass index (P < 0.001), shortened activated partial thromboplastin time (P < 0.01), and higher levels of fibrinogen, Factor VIII, and protein S activity (P < 0.05) compared to healthy control subjects. In addition, fibrinolytic capacity was impaired in patients with CD as reflected by prolonged clot lysis time (P < 0.001) and higher levels of plasminogen activator inhibitor type 1, thrombin-activatable fibrinolysis inhibitor, and α2-antiplasmin (P < 0.01). There were no statistically significant differences in von Willebrand factor:antigen, antithrombin, and protein C activity. After 80 d, 15 of 17 patients had normalized urinary free cortisol excretion. Despite biochemical remission, only slight decreases in antithrombin (P < 0.01) and thrombin-activatable fibrinolysis inhibitor (P < 0.05) levels were observed. Other parameters of coagulation and fibrinolysis did not change significantly.

CONCLUSIONS

The hypercoagulable state in patients with CD, which is explained by both increased production of procoagulant factors and impaired fibrinolysis, is not reversible upon short-term biochemical remission after successful medical therapy. This may have implications for the duration of anticoagulant prophylaxis in patients with (cured) CD.

Individualised therapy of angiotensin converting enzyme (ACE) inhibitors in stable coronary artery disease: overview of the primary results of the PERindopril GENEtic association (PERGENE) study

In patients with stable coronary artery disease (CAD) without overt heart failure, ACE inhibitors are among the most commonly used drugs as these agents have been proven effective in reducing the risk of cardiovascular events. Considerable individual variations in the blood pressure response to ACE inhibitors are observed and as such heterogeneity in clinical treatment effect would be likely as well. Assessing the consistency of treatment benefit is essential for the rational and cost-effective prescription of ACE inhibitors. Information on heterogeneities in treatment effect between subgroups of patients could be used to develop an evidence-based guidance for the installation of ACE-inhibitor therapy. Obviously, therapy should only be applied in those patients who most likely will benefit. Attempts to develop such treatment guidance by using clinical characteristics have been unsuccessful. No heterogeneity in risk reduction by ACE inhibitors has been observed in relation to relevant clinical characteristics. A new approach to such 'guided-therapy' could be to integrate more patient-specific characteristics such as the patients' genetic information. If proven feasible, pharmacogenetic profiling could optimise patients' benefit of treatment and reduce unnecessary treatment of patients. Cardiovascular pharmacogenetic research of ACE inhibitors in coronary artery disease patients is in a formative stage and studies are limited. The PERGENE study is a large pharmacogenetic substudy of the EUROPA trial, aimed to assess the achievability of pharmacogenetic profiling. We provide an overview of the main results of the PERGENE study in terms of the genetic determinants of treatment benefit and blood pressure response. The main results of the PERGENE study show a pharmacogenetic profile related to the treatment benefit of perindopril identifying responders and non-responders to treatment.

Fibrinogen γ' levels in patients with intracerebral hemorrhage

BACKGROUND

The fibrinogen γ' variant (γ') has both antithrombotic and prothrombotic properties when compared to normal fibrinogen. It may therefore be of relevance in intracerebral hemorrhage and intraventricular extension of the bleeding.

OBJECTIVE

To study the role of γ' in intracerebral hemorrhage, and in intraventricular extension of the hemorrhage.

PATIENTS/METHODS

We performed a case-control study in 156 controls and 55 patients with intracerebral hemorrhage, with and without intraventricular extension. Levels of fibrinogen γ' and the γ'/total fibrinogen ratio were measured in all participants.

RESULTS

Levels of γ' were increased in patients with intracerebral hemorrhage when compared with controls (0.40 vs 0.32g/l, p<0.001). The γ'/total fibrinogen ratio was similar in patients and controls (0.092 vs 0.096 p=0.42). There was evidence for an unfavorable outcome in patients with fibrinogen levels in the highest tertile compared with the lowest tertile (OR 4.0, 95%CI 1.1-15.2), and a nonsignificant trend toward unfavorable outcome with higher levels of γ' (p-value for trend=0.06).

CONCLUSIONS

Our study shows that absolute levels of fibrinogen γ' are increased in patients with intracerebral hemorrhage, but relative levels are similar in patients and controls, suggesting that the absolute rise in γ' is an acute phase response.

Genetic determinants of von Willebrand factor levels and activity in relation to the risk of cardiovascular disease: a review

It is well established that high plasma von Willebrand factor (VWF) levels are associated with an increased risk of arterial thrombosis, including myocardial infarction and ischemic stroke. As plasma VWF levels are, to a large extent, genetically determined, numerous association studies have been performed to assess the effect of genetic variability in the VWF gene (VWF) on VWF antigen and activity levels, and on the risk of arterial thrombosis. Genetic variations in other regulators of VWF, including the ABO blood group, ADAMTS-13, thrombospondin-1 and the recently identified SNARE protein genes, have also been investigated. In this article, we review the current literature as exploring the associations between genetic variations and the risk of arterial thrombosis may help elucidate the role of VWF in the pathogenesis of arterial thrombosis. However, as studies frequently differ in design, population and endpoint, and are often underpowered, it remains unclear whether VWF is causally related to the occurrence of arterial thrombosis or primarily mirrors endothelial dysfunction, which predisposes to atherosclerosis and subsequent arterial thrombosis. Nevertheless, current studies provide interesting results that do not exclude the possibility of VWF as causal mediator and justify further research into the relationship between VWF and arterial thrombosis. Large prospective studies are required to further establish the role of VWF in the occurrence of arterial thrombosis.

Molecular weight fibrinogen variants alter gene expression and functional characteristics of human endothelial cells

BACKGROUND

Fibrin is a temporary matrix that not only seals a wound, but also provides a temporary matrix structure for invading cells during wound healing. Two naturally occurring fibrinogen variants, high molecular weight (HMW) and low molecular weight (LMW) fibrinogen, display different properties in supporting angiogenesis in vivo and in vitro.

OBJECTIVES

This study was aimed at investigating the functional characteristics and molecular mechanisms of human microvascular endothelial cells (HMVECs) cultured on HMW and LMW fibrin matrices.

METHODS AND RESULTS

HMVECs on HMW fibrin matrices showed increased proliferation and tube formation as compared with their counterparts on unfractionated and LMW fibrin. Degradation of HMW fibrin was markedly enhanced by the presence of HMVECs, that of LMW fibrin was enhanced only slightly. However, the expression levels of fibrinolysis-regulating proteins and integrins were similar. Subsequent microarray analysis revealed that the expression of 377 genes differed significantly between HMVECs cultured on HMW fibrin and those cultured on LMW fibrin. Among these genes, UNC5B, DLL4 and the DLL4-Notch downstream targets Hey1, Hey2 and Hes1 showed increased expression in HMVECs on LMW fibrin. However, pharmacologic and genetic (DLL4 small interfering RNA) inhibition of DLL4-Notch signaling blunted rather than enhanced proliferation and tube formation by HMVECs on both fibrin variants.

CONCLUSIONS

Heterogeneity in naturally occurring fibrinogen strongly influences endothelial cell proliferation and tube formation, and causes alterations in gene expression, including that of DLL4-Notch. The higher fibrinolytic sensitivity of HMW fibrin in the presence of HMVECs contributes to increased tube formation. Although the expression of DLL4-Notch was altered, it did not explain the enhanced tube formation in HMW fibrin. This study provides new perspectives for biological and tissue engineering applications.

The influence of variation in the P2Y12 receptor gene on in vitro platelet inhibition with the direct P2Y12 antagonist cangrelor

Novel P2Y12 inhibitors are in development to overcome the occurrence of atherothrombotic events associated with poor responsiveness to the widely used P2Y12 inhibitor clopidogrel. Cangrelor is an intravenously administered P2Y12 inhibitor that does not need metabolic conversion to an active metabolite for its antiplatelet action, and as a consequence exhibits a more potent and consistent antiplatelet profile as compared to clopidogrel. It was the objective of this study to determine the contribution of variation in the P2Y12 receptor gene to platelet aggregation after in vitro partial P2Y12 receptor blockade with the direct antagonist cangrelor. Optical aggregometry was performed at baseline and after in vitro addition of 0.05 and 0.25 microM cangrelor to the platelet-rich plasma of 254 healthy subjects. Five haplotype-tagging (ht)-SNPs covering the entire P2Y12 receptor gene were genotyped (rs6798347C>t, rs6787801T>c, rs9859552C>a, rs6801273A>g and rs2046934T>c [T744C]) and haplotypes were inferred. The minor c allele of SNP rs6787801 was associated with a 5% lower 20 microM ADP-induced peak platelet aggregation (0.05 microM cangrelor, p<0.05). Aa homozygotes for SNP rs9859552 showed 20% and 17% less inhibition of platelet aggregation with cangrelor when compared to CC homozygotes (0.05 and 0.25 microM cangrelor respectively; p<0.05). Results of the haplotype analyses were consistent with those of the single SNPs. Polymorphisms of the P2Y12 receptor gene contribute significantly to the interindividual variability in platelet inhibition after partial in vitro blockade with the P2Y12 antagonist cangrelor.

Biological variation in inflammatory and hemostatic markers

BACKGROUND

Concentrations of inflammatory and hemostatic variables are influenced by biological variation, which is the natural within-subject variation over time.

OBJECTIVES

The aim of this study was to determine fibrinogen, C-reactive protein (CRP), platelet aggregation, thrombin generation and prothrombin time (PT): (i) the number of repeated measurements needed to obtain the true habitual concentration of an individual; (ii) the recommended analytical imprecision for diagnosis and monitoring; (iii) the recommended analytical bias; (iv) the contribution of analytical imprecision to test result variability; (v) the index of individuality; (vi) the reference change value; and (vii) the seasonal variation.

SUBJECTS AND METHODS

We collected 520 blood samples over a 1-year period from 40 healthy individuals, and determined the between-subject, within-subject and seasonal variation in fibrinogen, CRP, platelet aggregation, thrombin generation and PT.

RESULTS

One or two repeated measurements were sufficient to establish the true habitual concentration, except for platelet aggregation and peak thrombin generation, where at least four and nine repeated measurements were needed, respectively. For diagnosis, the maximal recommended coefficient of analytical variation (CV) was 4%-27%, except for CRP (77.7%). For monitoring, these CVs were on average 3% lower. Recommended analytical bias varied between 1.7% and 33.2%. Finally, seasonal variation was observed in concentrations of fibrinogen and thrombin generation, which could explain approximately 11% of their total variation.

CONCLUSION

This study provides insights into the biological variability of selected inflammatory and hemostatic markers, which can be used for sample size calculations and to determine the analytical quality specifications for their respective assays.

The role of thrombin activatable fibrinolysis inhibitor in arterial thrombosis at a young age: the ATTAC study

BACKGROUND AND OBJECTIVES

Thrombin activatable fibrinolysis inhibitor (TAFI) attenuates fibrinolysis and may therefore contribute to the pathophysiology of arterial thrombosis. The aim of the present study was to elucidate the pathogenetic role of TAFI levels and genotypes in young patients with arterial thrombosis.

PATIENTS AND METHODS

In a case-control study, 327 young patients with a recent first-ever event of coronary heart disease (CHD subgroup) or cerebrovascular disease (ischemic stroke subgroup) and 332 healthy young controls were included. TAFI levels [intact TAFI, activation peptide (TAFI-AP) and (in)activated TAFI (TAFIa(i)] and TAFI activity were measured and genetic variations in the TAFI gene (-438G/A, 505G/A and 1040C/T) were determined.

RESULTS

In the total group of patients, TAFIa(i) levels were higher (145.1 +/- 37.5%) than in controls (137.5 +/- 31.3%, P = 0.02). Plasma levels of intact TAFI, TAFI-AP and TAFI activity were similar in patients and controls. In the CHD subgroup (n = 218), intact TAFI levels were higher (109.4 +/- 23.0%) than in controls (102.8 +/- 20.7%, P = 0.02). In 325Ile/Ile homozygotes, lower TAFI levels and a decreased risk of arterial thrombosis were observed (OR 0.58, 95% CI 0.34-0.99) compared with patients with the common 325Thr/Thr genotype. This association was most evident in CHD patients (OR 0.48, 95% CI 0.26-0.90). Haplotype analyses supported a role for the Thr325Ile polymorphism.

CONCLUSIONS

TAFIa(i) levels were higher in patients with cardiovascular disease. Furthermore, the TAFI 325Thr/Ile polymorphism was associated with lower TAFI levels and with the risk of cardiovascular disease in young patients, especially in CHD.

Systematically missing confounders in individual participant data meta-analysis of observational cohort studies

One difficulty in performing meta-analyses of observational cohort studies is that the availability of confounders may vary between cohorts, so that some cohorts provide fully adjusted analyses while others only provide partially adjusted analyses. Commonly, analyses of the association between an exposure and disease either are restricted to cohorts with full confounder information, or use all cohorts but do not fully adjust for confounding. We propose using a bivariate random-effects meta-analysis model to use information from all available cohorts while still adjusting for all the potential confounders. Our method uses both the fully adjusted and the partially adjusted estimated effects in the cohorts with full confounder information, together with an estimate of their within-cohort correlation. The method is applied to estimate the association between fibrinogen level and coronary heart disease incidence using data from 154 012 participants in 31 cohorts.† Copyright © 2009 John Wiley & Sons, Ltd.

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.

Thrombin-activatable fibrinolysis inhibitor is associated with severity and outcome of severe meningococcal infection in children

BACKGROUND AND OBJECTIVES

In pediatric meningococcal sepsis, an imbalance between coagulation and fibrinolysis and proinflammatory action play major roles. We hypothesized that thrombin activatable fibrinolysis inhibitor (TAFI) and/or TAFI activation markers are involved in the pathogenesis of meningococcal sepsis.

PATIENTS AND METHODS

Children with severe meningococcal sepsis (n = 112) previously included in Rotterdam-based trials participated in this study. Clinical and laboratory parameters and severity scores were assessed. TAFI and TAFI activation markers were determined: TAFI activation peptide (TAFI-AP) and (in)activated TAFI [TAFIa(i)]. The -438G/A, Ala147Thr, and Thr325Ile polymorphisms were genotyped.

RESULTS

TAFI levels were significantly decreased in patients with meningococcal disease at admission compared to the convalescence state. TAFI was decreased in patients with septic shock vs. those with no shock. TAFI-AP levels were increased in patients with disseminated intravascular coagulation (DIC) vs. patients without DIC. TAFI-AP and TAFIa(i) were significantly increased in non-survivors vs. survivors. TAFI-AP levels and the TAFI-AP/TAFI ratio were also strongly correlated to severity scores and laboratory parameters. The TAFI 325Ile/Ile genotype was overrepresented in patients with DIC.

CONCLUSIONS

Activation markers of TAFI were associated with the occurrence of DIC and mortality in meningococcal sepsis patients. A determination of TAFI, TAFI-AP, and TAFIa(i) is required to enable coherent interpretation of the role of TAFI in disease.

Thrombin-activatable fibrinolysis inhibitor is associated with severity and outcome of severe meningococcal infection in children

BACKGROUND AND OBJECTIVES

In pediatric meningococcal sepsis, an imbalance between coagulation and fibrinolysis and proinflammatory action play major roles. We hypothesized that thrombin activatable fibrinolysis inhibitor (TAFI) and/or TAFI activation markers are involved in the pathogenesis of meningococcal sepsis.

PATIENTS AND METHODS

Children with severe meningococcal sepsis (n = 112) previously included in Rotterdam-based trials participated in this study. Clinical and laboratory parameters and severity scores were assessed. TAFI and TAFI activation markers were determined: TAFI activation peptide (TAFI-AP) and (in)activated TAFI [TAFIa(i)]. The -438G/A, Ala147Thr, and Thr325Ile polymorphisms were genotyped.

RESULTS

TAFI levels were significantly decreased in patients with meningococcal disease at admission compared to the convalescence state. TAFI was decreased in patients with septic shock vs. those with no shock. TAFI-AP levels were increased in patients with disseminated intravascular coagulation (DIC) vs. patients without DIC. TAFI-AP and TAFIa(i) were significantly increased in non-survivors vs. survivors. TAFI-AP levels and the TAFI-AP/TAFI ratio were also strongly correlated to severity scores and laboratory parameters. The TAFI 325Ile/Ile genotype was overrepresented in patients with DIC.

CONCLUSIONS

Activation markers of TAFI were associated with the occurrence of DIC and mortality in meningococcal sepsis patients. A determination of TAFI, TAFI-AP, and TAFIa(i) is required to enable coherent interpretation of the role of TAFI in disease.

Interleukin 10: a new risk marker for the development of restenosis after percutaneous coronary intervention

Genetic factors appear to be important in the process of restenosis after percutaneous coronary intervention (PCI), as well as in inflammation, a pivotal factor in restenosis. An important mediator in the inflammatory response is interleukin (IL)-10. Our aim was to study whether genetic variants in IL-10 predispose to the risk of restenosis. The GENetic DEterminants of Restenosis (GENDER) study included 3104 patients treated with successful PCI. Target vessel revascularization (TVR) was chosen as primary end point. Genotyping of the -2849G/A, -1082G/A, -592C/A and +4259A/G polymorphisms of the IL-10 gene was performed by MassArray platform. After adjusting for clinical variables, three polymorphisms significantly increased the risk of restenosis (-2849AA: relative risk (RR), 1.7, 95% confidence interval (CI), 1.2-2.5; -1082AA: RR, 1.4, 95% CI, 1.1-1.8 and +4259GG: RR, 2.0, 95% CI, 1.4-2.8). To further exclude possible involvement of neighboring genes due to LD in the IL-10 locus, additional polymorphisms were genotyped. The results reveal that association of the IL-10 gene with restenosis is independent of flanking genes. Our findings demonstrate that IL-10 is associated with restenosis and therefore support the hypothesis that anti-inflammatory genes also may be involved in developing restenosis. Furthermore, they may provide a new targeting gene for drug-eluting stents.

Molecular weight fibrinogen variants determine angiogenesis rate in a fibrin matrix in vitro and in vivo

BACKGROUND

During wound repair, fibrin acts both as a barrier to prevent blood loss and as a temporary matrix for the invasion and ingrowth of endothelial and tissue cells. A well-controlled angiogenesis process in the fibrinous exudate matrix is crucial for optimal wound healing. The composition and structure of the fibrin matrix are important determinants of the invasion of endothelial cells and capillary-tube formation into the matrix.

OBJECTIVE

Fibrinogen circulates in a high and low molecular weight form (HMW and LMW, respectively) and the purpose of this study was to investigate how fibrin matrices from these naturally occurring fibrinogen variants influence angiogenesis. Angiogenesis was studied using an in vitro model in which human microvascular endothelial cells (hMVEC) were cultured on three-dimensional fibrin matrices from different fibrinogen forms, and using two in vivo mouse models.

RESULTS

The in vitro angiogenesis in an HMW-fibrin matrix shows increased cell and tubular structure ingrowth compared with unfractionated fibrin matrix (median increase 58%, range 46-234%). The ingrowth of tubular structures in an LMW-fibrin matrices is decreased when compared with unfractionated fibrin (median decrease 70%, range 67-100%). Similar results were observed for in vivo angiogenesis.

CONCLUSIONS

The naturally occurring fibrinogen variants HMW- and LMW-fibrin modulate the angiogenic capacity of endothelial cells in fibrin matrices. The different effects of the molecular weight fibrinogen variants provide further insight in the matrix characteristics in angiogenesis and could possibly be applied in the context of tissue engineering and wound healing.

Fibrin structure and wound healing

Fibrinogen and fibrin play an important role in blood clotting, fibrinolysis, cellular and matrix interactions, inflammation, wound healing, angiogenesis, and neoplasia. The contribution of fibrin(ogen) to these processes largely depends not only on the characteristics of the fibrin(ogen) itself, but also on interactions between specific-binding sites on fibrin(ogen), pro-enzymes, clotting factors, enzyme inhibitors, and cell receptors. In this review, the molecular and cellular biology of fibrin(ogen) is reviewed in the context of cutaneous wound repair. The outcome of wound healing depends largely on the fibrin structure, such as the thickness of the fibers, the number of branch points, the porosity, and the permeability. The binding of fibrin(ogen) to hemostasis proteins and platelets as well as to several different cells such as endothelial cells, smooth muscle cells, fibroblasts, leukocytes, and keratinocytes is indispensable during the process of wound repair. High-molecular-weight and low-molecular-weight fibrinogen, two naturally occurring variants of fibrin, are important determinants of angiogenesis and differ in their cell growth stimulation, clotting rate, and fibrin polymerization characteristics. Fibrin sealants have been investigated as matrices to promote wound healing. These sealants may also be an ideal delivery vehicle to deliver extra cells for the treatment of chronic wounds.

Genetic influence on thrombotic risk markers in the elderly--a Danish twin study

OBJECTIVE

Several hemostatic variables are identified as cardiovascular risk markers. In young and middle-aged individuals, plasma concentrations of these variables are partly determined by genetic factors. The genetic contribution to cardiovascular disease (CVD) decreases with increasing age, and it is therefore important to determine the heritability of hemostasis also in the elderly.

METHODS

The heritability of plasma levels of factor VII, fibrinogen, tissue factor, tissue factor pathway inhibitor, von Willebrand factor, thrombin activatable fibrinolysis inhibitor (TAFI), and D-dimer was determined in 130 monozygotic and 155 dizygotic same-sex twin pairs, aged 73-94 years, who participated in the Longitudinal Study of Aging of Danish Twins. Furthermore, we determined the influence of promoter polymorphisms in corresponding genes on the plasma level variation.

RESULTS

Genetic factors accounted for 33% (D-dimer) to 71% (TAFI) of the variation in plasma levels. Polymorphisms were associated with concentrations of FVII and TAFI in sib-pair based analyses, but in linkage analyses the polymorphisms did not explain a significant part of the genetic variation for any of the variables.

CONCLUSIONS

Concentrations of hemostatic variables have a substantial genetic variation in the elderly, but in this study the promoter polymorphisms only explained a minimal part of this variation.

Plasma fibrinogen level and the risk of major cardiovascular diseases and nonvascular mortality: an individual participant meta-analysis

CONTEXT

Plasma fibrinogen levels may be associated with the risk of coronary heart disease (CHD) and stroke.

OBJECTIVE

To assess the relationships of fibrinogen levels with risk of major vascular and with risk of nonvascular outcomes based on individual participant data.

DATA SOURCES

Relevant studies were identified by computer-assisted searches, hand searches of reference lists, and personal communication with relevant investigators.

STUDY SELECTION

All identified prospective studies were included with information available on baseline fibrinogen levels and details of subsequent major vascular morbidity and/or cause-specific mortality during at least 1 year of follow-up. Studies were excluded if they recruited participants on the basis of having had a previous history of cardiovascular disease; participants with known preexisting CHD or stroke were excluded.

DATA EXTRACTION

Individual records were provided on each of 154,211 participants in 31 prospective studies. During 1.38 million person-years of follow-up, there were 6944 first nonfatal myocardial infarctions or stroke events and 13,210 deaths. Cause-specific mortality was generally available. Analyses involved proportional hazards modeling with adjustment for confounding by known cardiovascular risk factors and for regression dilution bias.

DATA SYNTHESIS

Within each age group considered (40-59, 60-69, and > or =70 years), there was an approximately log-linear association with usual fibrinogen level for the risk of any CHD, any stroke, other vascular (eg, non-CHD, nonstroke) mortality, and nonvascular mortality. There was no evidence of a threshold within the range of usual fibrinogen level studied at any age. The age- and sex- adjusted hazard ratio per 1-g/L increase in usual fibrinogen level for CHD was 2.42 (95% confidence interval [CI], 2.24-2.60); stroke, 2.06 (95% CI, 1.83-2.33); other vascular mortality, 2.76 (95% CI, 2.28-3.35); and nonvascular mortality, 2.03 (95% CI, 1.90-2.18). The hazard ratios for CHD and stroke were reduced to about 1.8 after further adjustment for measured values of several established vascular risk factors. In a subset of 7011 participants with available C-reactive protein values, the findings for CHD were essentially unchanged following additional adjustment for C-reactive protein. The associations of fibrinogen level with CHD or stroke did not differ substantially according to sex, smoking, blood pressure, blood lipid levels, or several features of study design.

CONCLUSIONS

In this large individual participant meta-analysis, moderately strong associations were found between usual plasma fibrinogen level and the risks of CHD, stroke, other vascular mortality, and nonvascular mortality in a wide range of circumstances in healthy middle-aged adults. Assessment of any causal relevance of elevated fibrinogen levels to disease requires additional research.

No effect of C-reactive protein on early atherosclerosis development in apolipoprotein E*3-leiden/human C-reactive protein transgenic mice

OBJECTIVE

C-reactive protein (CRP) has been associated with risk of cardiovascular disease. It is not clear whether CRP is causally involved in the development of atherosclerosis. Mouse CRP is not expressed at high levels under normal conditions and increases in concentration only several-fold during an acute phase response. Because the dynamic range of human CRP is much larger, apolipoprotein E*3-Leiden (E3L) transgenic mice carrying the human CRP gene offer a unique model to study the role(s) of CRP in atherosclerosis development.

METHODS AND RESULTS

Atherosclerosis development was studied in 15 male and 15 female E3L/CRP mice; E3L transgenic littermates were used as controls. The mice were fed a hypercholesterolemic diet to induce atherosclerosis development. Cholesterol exposure did not differ between E3L/CRP and E3L mice. Plasma CRP levels were on average 10.2+/-6.5 mg/L in male E3L/CRP mice, 0.2+/-0.1 mg/L in female E3L/CRP mice, and undetectable in E3L mice. Quantification of atherosclerosis showed that lesion area in E3L/CRP mice was not different from that in E3L mice.

CONCLUSIONS

This study demonstrates that mildly elevated levels of CRP in plasma do not contribute to the development of early atherosclerosis in hypercholesterolemic E3L/CRP mice.

Logistics and quality control for DNA sampling in large multicenter studies

To study associations between genetic variation and disease, large bio-banks need to be created in multicenter studies. Therefore, we studied the effects of storage time and temperature on DNA quality and quantity in a simulation experiment with storage up to 28 days frozen, at 4 degrees C and at room temperature. In the simulation experiment, the conditions did not influence the amount or quality of DNA to an unsatisfactory level. However, the amount of extracted DNA was decreased in frozen samples and in samples that were stored for > 7 days at room temperature. In a sample of patients from 24 countries of the EUROPA trial obtained by mail with transport times up to 1 month DNA yield and quality were adequate. From these results we conclude that transport of non-frozen blood by ordinary mail is usable and practical for DNA isolation for polymerase chain reaction in clinical and epidemiological studies.

Inflammation, thrombosis and atherosclerosis: results of the Glostrup study

Inflammation and thrombosis are important mechanisms in cardiovascular disease, as illustrated by the consistent association between inflammatory and hemostatic variables and the risk of cardiovascular events in epidemiological studies. However, the relationship between plasma concentrations of inflammatory and hemostatic markers and the severity of atherosclerosis is not yet well studied. We have evaluated 325 men and 370 women of 60 years, participating in the Danish Glostrup study. We diagnosed atherosclerosis by ultrasonographic measurement of intima-media thickness (IMT) of the right carotid artery and the assessment of plaque occurrence. Plasma samples were analyzed for the concentration of C-reactive protein (CRP), fibrinogen, d-dimer, plasminogen activator inhibitor type-1 (PAI-1) antigen and activity, tissue-type plasminogen activator (t-PA) antigen and activity, factor VII (FVII) antigen, FVII coagulant activity (FVII:C) and activated FVII (FVIIa). DNA variations were determined for fibrinogen, PAI-1, t-PA, FVII, factor XIII and methylene tetrahydrofolate reductase (MTHFR). Subjects with high IMT (upper 10% of distribution, n = 63) had higher CRP levels [2.2 mg L-1 (SE 0.3)] than subjects with IMT in the lowest tertile (n = 217) [1.7 mg L-1 (SE 0.1), P = 0.04], whereas there was no association between the hemostatic variables and IMT. There was an association between fibrinogen and d-dimer concentrations and number of plaques (P < 0.01), whereas there were no associations between CRP and the other hemostatic variables and the number of plaques. Genetic variation in the t-PA and MTHFR gene was associated with IMT. In conclusion, in the Glostrup population study, thrombosis and inflammation are associated with the severity of atherosclerosis, as reflected by IMT and plaque occurrence.

The association between extrinsic activated protein C resistance and venous thromboembolism in women

Recently, discussions have focused on the question of whether acquired APC resistance (APCsr) is a clue to the observed association between risk of venous thromboembolism (VTE) and OC use especially with the so-called third-generation OCs. It seems plausible that abnormalities in an extrinsic-based APCsr reflect an increased risk of VTE in women, but this has not yet been properly studied. The objective of our study was to determine whether there was an association of extrinsic APC resistance with VTE risk in a case-control study. Sixty-seven women with confirmed VTE diagnosis were consecutively recruited in primary health care settings, interviewed and blood samples were taken at least 6 months after VTE. Cases were age-matched to 290 population controls. Extrinsic APC resistance was measured as normalized APC ratio (APCsr). The effect of APC on tissue factor-initiated thrombin generation was measured in plasma using alpha2-macroglobulin attached thrombin activity as an endpoint. The extrinsic APCsr was significantly associated with factor V Leiden (FVL) mutation, both in the cases and in the controls. Also, in the women using OC, significantly higher values of APCsr were observed, which confirms the results of other studies. We did not identify a significant association between the extrinsic APCsr and VTE in women not using OC who are non-carriers of factor V Leiden using different approaches: comparison of medians, analyses with unconditional logistic regression using various cut-points of the APCsr distribution, and the comparison between the highest and the lowest quartile of APCsr. With all attempts, the risk estimates were close to unity. In conclusion, we were not able to find evidence for any association of extrinsic APCsr with VTE in women who were not using OCs and non-carriers of FVL.

Sensitive markers of inflammation make it possible to study the chronic process: the rise of interest in low levels of C-reactive protein

Increases in baseline levels of C-reactive protein (CRP) have been consistently identified as an independent risk indicator of cardiovascular events. The measurement of the low level is robust and well established. Increases in low levels of CRP can mark low-grade continuous inflammation and hyperresponse in acute situations. In addition, CRP can exert various actions on vascular cells and activates complement thus participating in infarction pathogenesis. Various cardiovascular drugs, notably statins, can induce a marked decrease in low levels of CRP, which is indicative of their beneficial effect on inflammation. Future studies need to demonstrate whether increases in baseline levels of CRP can become a useful practical addition to risk recognition strategies and possibly may also serve as an additional surrogate endpoint in cardiovascular disease treatments.