Increased impact of a contraceptive vaginal ring with ethinyl estradiol and nestorone on C-reactive protein

OBJECTIVE & STUDY DESIGN: In a parallel design, 23 and 22 healthy pre-menopausal women were randomly administered a contraceptive vaginal ring (CVR) delivering 150/15 μg Nestorone®/ethinyl estradiol (EE) daily or an oral contraceptive (OC) containing levonorgestrel and EE (150/30 μg) for three cycles, to compare the effects on C-reactive protein and other markers of inflammation. ANCOVA was performed with baseline values as covariate.

RESULTS

The CVR caused [estimate of difference (95% CI), 109% (16-275%)] higher levels of CRP than the OC, while no difference was observed for leukocyte 1% (-13/+17%) and monocyte counts 6% (-9/+23%). The greater increase in CRP was confined to CVR recipients exhibiting low pre-treatment CRP-levels, whereas no difference was observed in the increases for recipients in the highest tertile of pre-treatment CRP levels.

CONCLUSION

The difference in CRP rise in CVR and OC users does not correspond with the effects on other markers of inflammation and is most likely due to a specific difference in the effect of ethinyl-estradiol combined with nestorone in cases with low CRP.

Biological variation in tPA-induced plasma clot lysis time

Hypofibrinolysis is a risk factor for venous and arterial thrombosis, and can be assessed by using a turbidimetric tPA-induced clot lysis time (CLT) assay. Biological variation in clot lysis time may affect the interpretation and usefulness of CLT as a risk factor for thrombosis. Sufficient information about assay variation and biological variation in CLT is not yet available. Thus, this study aimed to determine the analytical, within-subject and between-subject variation in CLT. We collected blood samples from 40 healthy individuals throughout a period of one year (average 11.8 visits) and determined the CLT of each plasma sample in duplicate. The mean (± SD) CLT was 83.8 (± 11.1) minutes. The coefficients of variation for total variation, analytical variation, within-subject variation and between-subject variation were 13.4%, 2.6%, 8.2% and 10.2%, respectively. One measurement can estimate the CLT that does not deviate more than 20% from its true value. The contribution of analytical variation to the within-subject variation was 5.0%, the index of individuality was 0.84 and the reference change value was 23.8%. The CLT was longer in the morning compared to the afternoon and was slightly longer in older individuals (> 40 years) compared to younger (≤40 years) individuals. There was no seasonal variation in CLT and no association with air pollution. CLT correlated weakly with fibrinogen, C-reactive protein, prothrombin time and thrombin generation. This study provides insight into the biological variation of CLT, which can be used in future studies testing CLT as a potential risk factor for thrombosis.

Introduction to haemostasis from a pharmacodynamic perspective

Biochemical characterization of the haemostatic system has advanced significantly in the past decades. Sub-systems, such as coagulation, fibrinolysis, blood cells and platelets and the vessel wall have been studied by specialists, mostly separately and independently. The time has come to integrate the approaches, and, in particular, to develop tests to document the state of the whole system and to have available adequate pharmacodynamic tests to evaluate treatments. Many examples are available to show that traditional general methods of clotting and lysis do not provide the information that is desired. The present tendency is to use specific methods for specific factors or effects which are very limited in pharmacological information. There is also increasing awareness of the occurrence of rather broad interindividual variability in the haemostatic system. This suggests that individually tailored treatments are required. This is the more relevant since haemostasis is a balance and treatment should be positioned between efficacy and safety. The conclusion is reached that there is a need for integrated or global methods or sets of methods that reflect the complexity and individual status appropriately and allow the practitioner to judge the effects of interventions and their individual aspects.

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.

Effects of hormone treatment on hemostasis variables

A survey was made of the changes in hemostasis and related inflammatory biomarkers for hormone treatments (HT) of women. Treatments included were oral and non-oral estrogens combined or not with progestogens, raloxifene, tamoxifene, tibolone and ethinylestradiol in oral contraceptives with non-androgenic progestogens. Special attention was given to dosages lower than the present standard dose and we explored how treatment variants approached a situation of minimal changes in biomarkers. For oral unopposed estrogens, dose reduction effectively reduced the changes in some hemostasis markers, but not in a specific set of anticoagulant variables (antithrombin, protein S, tissue factor pathway inhibitor, and the endogenous thrombin potential assay for resistance to activated protein C). Inflammation markers from the liver showed a dose-dependent reduction but effects were not nullified at the lowest dose tested. It was concluded that adequate reduction of estrogen dose for these effects will coincide with the dose-range of efficacy. Androgenic progestogens may be suitable for further reducing the impact of estrogens on some of the anticoagulant variables; reductions of estrogen-induced C-reactive protein increases appear possible with specific progestogens (medroxyprogesterone actate, nomegestrol acetate). For non-oral unopposed estrogens, all variables except inflammation biomarkers from the vascular wall showed minimal changes. Reduction in vascular inflammatory biomarkers, considered to mark anti-inflammatory effects, is augmented by medroxyprogesterone actate or norethisterone acetate. It was concluded that unopposed, non-oral estrogen treatment is the present best available option approaching minimal effects of treatment on biomarkers. Progestogen selection requires more data. We postulated that minimal effects on all cardiovascular biomarkers should define the HT with maximal safety for venous and arterial vascular events. The survey has identified specific biomarkers sensitive to low-dose unopposed and opposed estrogen which can be used to characterize future preparations for HT.

On the usefulness of fibrinolysis variables in the characterization of a risk group for myocardial reinfarction

In a prospective study selected fibrinolysis variables were assessed in plasma samples from 29 consecutive patients recovering a first instance of acute myocardial infarction and the results were correlated with reinfarction during the next four years. Nine patients suffered a reinfarction leaving a group of 20 patients without evidence of relapse. The reinfarction group was characterized by lower tissue plasminogen activator activities in plasma euglobulins (p less than 0.05), significantly higher plasma concentrations of tissue plasminogen activator antigen (p less than 0.002) and a tendency to a higher plasma level of plasminogen activator inhibition capacity. There were no significant differences between the groups in plasma concentrations of plasminogen, histidine-rich glycoprotein, plasminogen kringle-4-binding-protein, and alpha 2-antiplasmin.

Strongly increased levels of fibrinogen elastase degradation products in patients with ischemic stroke

Ischemic stroke is associated with leucocyte activation. Activated leucocytes release elastase, an enzyme that can degrade fibrinogen. Fibrinogen elastase degradation products (FgEDP) may serve as a specific marker of elastase proteolytic activity. In a case-control study of 111 ischemic stroke patients and 119 controls, significantly higher FgEDP levels were observed in cases than in controls, both in the acute phase and in the convalescent phase. Results were only slightly affected by adjustment for cardiovascular risk factors, C-reactive protein and fibrinogen. Our findings suggest that FgEDP might be involved in the pathogenesis of stroke.

The impact of metabolic syndrome and CRP on vascular phenotype in type 2 diabetes mellitus

BACKGROUND

The burden of cardiovascular disease in diabetes mellitus type 2 (DM2) patients is variable. We hypothesize that metabolic syndrome (MS) and low-grade systemic inflammation modify the extent of atherosclerosis in DM2.

METHODS

Vascular phenotype was determined using the following endothelium-related, hemostatic, and sonographic endpoints in 62 DM2 patients with mild dyslipidemia: sVCAM, sE-selectin, von Willebrand factor (VWF), fibrinogen, s-thrombomodulin (sTM), tPA, PAI-1, flow-mediated dilation (FMD), and intima media thickness (IMT). The impact of MS load (number of criteria present), MS components, and CRP on these parameters was assessed.

RESULTS

Serum sVCAM, sTM, and tPA levels significantly increased with increasing MS load. IMT also significantly increased from 0.602+/-0.034 (one MS criterion) to 0.843+/-0.145 (four MS criteria, p=0.007). LogCRP significantly correlated with fibrinogen, PAI-1, and IMT. In a multiple regression (MR) model with age and gender as covariates, MS load predicted sVCAM and sTM; CRP predicted PAI-1 and fibrinogen; MS load and CRP simultaneously predicted tPA and IMT. For each MS criterion present, IMT significantly increased by 0.04 mm. An increase in CRP from 1 to 3 mg/L resulted in a significant increase of 0.04 mm. Patients with four MS criteria and inflammation (CRP >or=3 mg/L) are predicted to have a 0.21 mm thicker IMT than those without. A second stepwise MR analysis based on gender, traditional risk factors, diabetes-related parameters, renal function, individual MS criteria, and LogCRP as explanatory variables showed a significant effect of systolic and diastolic blood pressure, HDL, and LogCRP on IMT(r(2)=0.36, p<0.001).

CONCLUSION

MS and low-grade chronic inflammation have an independent impact on vascular phenotype including IMT in DM2.

Genome-wide association of major depression: description of samples for the GAIN Major Depressive Disorder Study: NTR and NESDA biobank projects

To identify the genomic regions that confer risk and protection for major depressive disorder (MDD) in humans, large-scale studies are needed. Such studies should collect multiple phenotypes, DNA, and ideally, biological material that allows gene expression analysis, transcriptomic, proteomic, and metabolomic studies. In this paper, we briefly review linkage studies of MDD and then describe the large-scale nationwide biological sample collection in Dutch twin families from the Netherlands Twin Register (NTR) and in participants in the Netherlands Study of Depression and Anxiety (NESDA). Within these studies, 1,862 participants with a diagnosis of MDD and 1,857 controls at low liability for MDD have been selected for genome-wide genotyping by the US Foundation for the National Institutes of Health Genetic Association Information Network. Stage 1 genome-wide association results are scheduled to be accessible before the end of 2007. Genome-wide association results are open-access and can be viewed at the dbGAP web portal (http://www.ncbi.nlm.nih.gov). Approved users can download the genotype and phenotype data, which have been made available as of 9 October 2007.

Effects of non-oral postmenopausal hormone therapy on markers of cardiovascular risk: a systematic review

OBJECTIVE

To review the effects of non-oral administration of postmenopausal hormone therapy (HT) on risk markers for atherosclerotic and venous thromboembolic disease.Non-oral postmenopausal HT appears not to increase venous thromboembolic risk, whereas the effect on coronary heart disease risk is less clear.

DESIGN

Systematic review of literature obtained from MEDLINE, EMBASE, and CENTRAL databases from 1980 until and including April 2006. Terms for "postmenopausal hormone therapy" and for "non-oral administration" were combined in the search.

SETTING

Randomized clinical trials.

PATIENT(S)

Postmenopausal women, both healthy and with established cardiovascular disease or specified cardiovascular risk factors

INTERVENTION(S)

Non-oral HT (e.g., transdermal or intranasal) compared with oral HT or no treatment/placebo.

MAIN OUTCOME MEASURE(S)

Lipoprotein(a), homocysteine, C-reactive protein (CRP), cell adhesion molecules, markers of endothelial dysfunction, coagulation, and fibrinolysis.

RESULT(S)

Seventy-two studies investigating either transdermal or intranasal administration were included. For non-oral HT, decreases in lipoprotein(a), cell adhesion molecules, and factor VII generally were significant, resistance to activated protein C (APCr) was slightly increased, and other markers including CRP and homocysteine did not change. Compared with oral HT, changes in CRP and APCr were smaller, changes in cell adhesion molecules and some fibrinolytic parameters tended to be smaller, whereas changes in other factors including lipoprotein(a) and homocysteine did not differ.

CONCLUSION(S)

Potentially unfavorable changes seen with oral HT on two important markers, CRP and APCr, are substantially smaller with non-oral HT. Non-oral HT has minor effects on the other cardiovascular risk markers studied. Therefore, compared with oral HT, non-oral HT appears be safer with respect to atherosclerotic and venous thromboembolic disease risk.

Comparison of the impact of vaginal and oral administration of combined hormonal contraceptives on hepatic proteins sensitive to estrogen

OBJECTIVE

We evaluated the effects of a new combined hormonal contraceptive vaginal ring (CVR) delivering the nonandrogenic progestin Nestorone (NES) and ethinyl estradiol (EE) on several key estrogen-sensitive hepatic proteins that may be markers for the risk of arterial or venous disease events and on blood pressure (BP). Because the pharmacologic androgenicity of the progestin in these formulations influences the hepatic impact of EE, we selected an oral contraceptive (OC) delivering the androgenic progestin levonorgestrel (LNG) and EE as the comparator. We also investigated the effect of delivery route, which is known to modify the hepatic effects of estradiol, but has not been widely studied with EE.

STUDY METHODS

Women, aged 18-34 years, with no contraindications to the use of combined OCs, were randomized to three cycles of treatment with a CVR delivering NES/EE (150/15 microg/day) or a combined OC providing LNG and EE (150/30 microg per tablet). Each cycle consisted of 21 days of active treatment, followed by 7 days without treatment. During the last weeks of the pretreatment and third treatment cycles, blood samples were obtained for determinations of plasma concentrations of angiotensinogen, an estrogen-sensitive hepatic protein, and serum concentrations of sex hormone-binding globulin (SHBG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), triglycerides (TG) and estrogen- and androgen-sensitive proteins. BP was also measured.

RESULTS

Of 47 women randomized, 45 completed the study (CVR: 23; OC: 22). Within-group comparisons over time by repeated-measure analysis of variance demonstrated statistically significant changes over time with both treatments for all hepatic proteins (p < .02) but not for TC. The within-group effects, presented as relative percent difference [95% confidence interval (CI)], were greatest for angiotensinogen [CVR: 227% (195-262%); OC: 251.3% (218-288%)] and SHBG [CVR: 306% (237-389%); OC: 55% (30-86)]. Both treatments were associated with small changes in systolic BP and diastolic BP (DBP), but only the within-group change in DBP for the OC group was statistically significant (p = .04). Between-treatment comparisons of third treatment cycle mean values were performed by analysis of covariance (baseline values as covariate). No statistically significant between-treatment differences were found for angiotensinogen, sensitive only to estrogen, or BP. Statistically significant treatment differences were found for all estrogen- and androgen-sensitive proteins (p < or = .002) but not for TC. When presented as relative percent difference between the effects of treatment (CVR-OC/OC; 95% CI of percent difference), the difference was largest for SHBG (159% [117-210%]); smaller relative percent differences were found for HDL-C [31.9% (18.5-46.8%)], LDL-C [23.6% (33.4% to -2.4%)] and TG [39.0% (14.0-69.4%)], but not TC.

CONCLUSION

Vaginal delivery of a combined hormonal contraceptive did not reduce the EE-associated changes in estrogen-sensitive hepatic proteins observed after use of a combined OC. Significant treatment differences between the NES/EE CVR and the LNG/EE OC were found for SHBG, HDL-C, LDL-C, and TG, proteins sensitive to androgen as well as estrogen. No treatment difference was observed for angiotensinogen, which is sensitive only to estrogen. The observed treatment differences were therefore most likely due to the difference in androgenicity between NES and LNG.

A national field study of quality assessment of CoaguChek point-of-care testing prothrombin time monitors

A system for quality assessment (QA) of the CoaguChek (Roche Diagnostics, Mannheim, Germany) point-of-care testing prothrombin time monitor has been developed by the European Concerted Action on Anticoagulation. Hitherto there has not been an adequate rapid method for CoaguChek QA. Sets of 5 certified international normalized ratio (INR) plasma samples were tested on 539 CoaguChek monitors by experienced staff at 9 Netherlands Thrombosis Centers and results compared with certified INR. A 15% or more deviation has been classified as significant deviation. Overall mean and certified INR values were similar, but 20.3% of participants showed a 15% or more deviation from the certified INR on at least 1 of the 5 QA plasma samples. Statistically significant differences in results with different lots of CoaguChek test strips were found. There is need for large scale QA of CoaguChek monitors. The importance of the 5 CoaguChek certified INR QA plasma samples being tested on a single occasion is demonstrated.

Performance goals for the laboratory testing of antithrombin, protein C and protein S

To achieve a reliable analytical quality for both monitoring and diagnostic testing, laboratories need to fulfil the widely accepted analytical performance goals based on the biological variation of the analytes of testing. Not only is the short-term analytical performance, which regularly is assessed by internal quality control procedures, of importance, but also the long-term analytical performance. To assess the long-term analytical performance, data obtained from an external quality assessment programme can be used. In this study we have used the evaluation model designed by the ECAT Foundation for the assessment of the longterm analytical performance, including imprecision, bias and total analytical error. The model was applied to the data from 136 different laboratories for the assay of antithrombin (activity), protein C (activity and antigen) and protein S (activity, total and free antigen). The imprecision (median; range), reflected by the long-term analytical coefficient of variation (LCV (A) ), was the lowest for antithrombin (7.6%; 2.6 - 43.8%) and the highest for protein S activity (17.2%; 4.3 - 88.6%). For bias and total error the same pattern was observed (antithrombin: 3.8%; 0.3 - 17.1% and 9.1%; 3.4 - 34.3%, respectively; protein S activity: 12.8%; 3.1 - 34.8% and 24.5%; 9.9 - 87.0%, respectively). For the majority of the laboratories (70 - 85%) the imprecision contributes considerably more to the total error than the bias. However the effect of the bias on the analytical quality is not negligible. Assays for antithrombin, protein C and protein S are mainly used for diagnostic testing. About 70 - 100% of the laboratories can fulfil the desirable performance goal for imprecision. The desirable performance goal for bias was reached by 50 - 95% of the laboratories. In all cases the highest numbers of laboratories fulfilling performance goals was obtained for the protein C variables. To improve the analytical quality in assays of antithrombin, protein C and protein S it is highly recommended that primarily imprecision (non-systematic failures) be suppressed. However the effect of the bias (systematic failures) on the analytical quality should not be neglected. A useful tool for determining the imprecision (LCV (A) ) and bias is the long-term analytical performance evaluation model as used by the ECAT Foundation.

Quality Assessment of CoaguChek Point-of-Care Prothrombin Time Monitors: Comparison of the European Community-Approved Procedure and Conventional External Quality Assessment

BACKGROUND

There is a need for dependable quality assessment (QA) of the widely used CoaguChek point-of-care testing prothrombin time monitor. By use of the prescribed set of 5 CoaguChek certified international normalized ratio (INR) QA plasmas, we compared the reliability of the immediate QA of individual monitors described in the European Community-recommended Technology Implementation Plan with conventional external QA analysis.

METHODS

Experienced staff tested CoaguChek point-of-care monitors in routine use for controlling oral anticoagulant dosage at 9 Netherlands Thrombosis Service Centres. Testing was performed with both the certified CoaguChek INR for a set of 5 QA individual plasmas from the Eur Con Action on Anticoag (ECAA) and conventional external QA analysis.

RESULTS

Patients brought 523 CoaguChek monitors to our service centers for assessment. The proportion with unsatisfactory performance indicated by a 15% deviation from the ECAA set was compared with 15% deviation from overall median INR of all CoaguChek monitors in the survey, as in conventional QA analysis. The results were similar (20.3% and 18.5%, respectively). Interlot differences of CoaguChek test strips were detected, but the incidence of unsatisfactory performance was similar with both analyses, from 6.5% to 37.5% with the certified INR method and from 5.9% to 33.3% with the overall median analysis.

CONCLUSIONS

The results validate the use of the European Action on Anticoagulation rapid single-instrument QA-specific procedure for CoaguChek users compared with the nonspecific conventional QA analysis that relies on deviation from the overall median INR.

Comparative effects of a contraceptive vaginal ring delivering a nonandrogenic progestin and continuous ethinyl estradiol and a combined oral contraceptive containing levonorgestrel on hemostasis variables

OBJECTIVE

This study aimed to compare the effects on hemostasis variables of a contraceptive vaginal ring with those of an oral contraceptive.

STUDY DESIGN

Twenty-three and 22 healthy premenopausal women were randomized to the contraceptive vaginal ring (150 microg Nestorone and 15 microg ethinyl estradiol) or Stediril 30 during 3 cycles. Analysis of covariance was performed with baseline values as covariate.

RESULTS

The contraceptive vaginal ring changed most hemostasis variables similarly but raised (95% confidence intervals of percent treatment differences) Factor VIIt (28% to 49%), extrinsic activated protein C resistance (14% to 65%), and sex hormone-binding globulin (117% to 210%) and lowered Protein S (-32% to -16%) and the global activated partial thromboplastin time-based activated protein C resistance (-12% to -2%) more than the oral contraceptive.

CONCLUSION

The contraceptive vaginal ring affected some measured hemostasis variables and sex hormone-binding globulin differently from the oral contraceptive, most likely because of difference in androgenicity of the progestins. The results suggest that the contraindications for oral contraceptive use would also apply to the tested contraceptive vaginal ring.

A prospective study on the effects on hemostasis of two oral contraceptives containing drospirenone in combination with either 30 or 20 microg ethinyl estradiol and a reference containing desogestrel and 30 microg ethinyl estradiol

PURPOSE

In this open-label, randomized study, we assessed the effects on hemostasis of two combined oral contraceptives containing drospirenone (DRSP) as progestogen component.

METHODS

Three milligrams of DRSP, a progestogen with antimineralocorticoid activity, was combined with either 30 or 20 microg ethinyl estradiol (EE) (DRSP/30EE; DRSP/20EE) and compared with a preparation containing 150 microg desogestrel (DSG) and 30 microg ethinyl estradiol (DSG/30EE). A total of 75 healthy female volunteers aged 18-35 years were enrolled. The hemostasis variables were measured in the medication-free precycle (baseline); in the first, third and sixth treatment cycle; and in the follow-up phase. The target variables for comparison were the relative changes from baseline to Cycle 6.

RESULTS

Data of 25 volunteers in each group were valid for the per-protocol evaluation. Most changes in hemostasis variables were similar in the three treatment groups. All procoagulatory variables and the anticoagulatory variable protein C antigen increased slightly, while protein S antigen and activity decreased. For fibrinogen and protein S activity, the changes were statistically significant: less pronounced with DRSP/20EE compared to DSG/30EE at Cycle 6. There were no statistically significant differences in the changes of antifibrinolytic variables, the global clotting tests and D-dimer. All pairwise comparisons of DRSP/30EE vs. DSG/30EE yielded nonsignificant results; however, there was a trend of a lower impact of DRSP/20EE on nearly all hemostatic parameters compared to the 30EE products. All three study treatments were safe and well tolerated by the volunteers and provided adequate contraceptive reliability.

CONCLUSION

The changes in the hemostatic variables for DRSP/20EE were less pronounced compared to DSG/30EE and DRSP/30EE. The results were in accordance with previous reports on effects of similar OCs.

Genetic influences on fibrinogen, tissue plasminogen activator-antigen and von Willebrand factor in males and females

Differences in genetic influence on death from CHD between males and females have been reported. Haemostatic factors have consistently been associated with risk for coronary heart disease (CHD), but sex differences in genetic architecture have not been studied. This study in middle-aged twins investigates whether there are sex differences in means and in genetic and/or environmental variance components of haemostatic risk factors for CHD. A total of 93 monozygotic twin pairs (44 male and 49 female) and 116 dizygotic twin pairs (36 male, 40 female and 40 opposite sex) were available for this study. Structural equation modelling was used to estimate the relative influence of genetic and environmental factors on variation in levels of fibrinogen, tissue plasminogen activator (tPA) antigen and von Willebrand factor (vWF). Mean levels of tPA and vWF increased with age. Oral contraceptive pill (OCP) and menopause had significant influences on levels of fibrinogen and tPA. Genetic influences explained 39, 66 and 72% of the variation in levels of fibrinogen, tPA and vWF, respectively. No quantitative or qualitative differences of genetic influences on haemostatic levels were seen between males and females. Haemostatic factors may account for a significant part of the genetic risk for cardiovascular disease. No difference in genetic architecture for levels of fibrinogen, tPA or vWF was observed between males and females.

Estrogen receptor 1 haplotype does not regulate oral contraceptive-induced changes in haemostasis and inflammation risk factors for venous and arterial thrombosis

BACKGROUND

Administration of oral contraceptives (OCs) has profound effects on the plasma levels of haemostasis and inflammation variables, resulting in an increased thrombosis risk. Individuals show large differences in the response of these variables to OCs. Polymorphism in the estrogen receptor-1 (ER1) gene may explain part of this inter-individual response.

METHODS

We investigated the relationship between variants (c.454-397T>C and c.454-351A>G polymorphisms and the combined haplotype) in the ER1 gene in relation to changes in haemostasis and inflammation variables that are known risk factors for thrombosis in 507 healthy, nonsmoking, nulliparous women receiving six cycles of monophasic OCs with 20, 30 or 50 microg/day estrogen.

RESULTS

A significant relationship was observed between the ER1 haplotype and changes in tissue-type plasminogen activator activity (P = 0.006), but no clear interaction pattern between the genotypes or between the estrogen doses was seen. No relationships were observed for the other variables, neither in the haplotype nor in the single polymorphism analysis.

CONCLUSION

The ER1 haplotype does not have a strong effect on the estrogen-induced changes in haemostasis and inflammation risk markers for arterial and venous thrombosis.

The Harmonization of Quantitative Test Results of Different D-Dimer Methods

Nowadays D-dimer testing is frequently applied in the diagnosis of venous thromboembolism. However, the test results of different quantitative D-dimer tests can differ significantly. The background of this variability, which is mainly caused by the variety of fibrin degradation products in plasma, the specificity of D-dimer assays, and the calibrators used in the test, is summarized here. Because D-dimer is not a single entity in plasma but a mixture of heterogeneous fibrin degradation products, method standardization is in principle impossible. Efforts undertaken in the past to standardize D-dimer methods are summarized. All these projects failed and it was concluded that only harmonization of D-dimer test results seems to be feasible. The results of a large field study on which a new approach to the harmonization of quantitative D-dimer methods will be based is summarized in this article. This approach seems to be an adequate solution for overcoming the practical problem of variation of test outcome in different D-dimer assays.

Relationship of C-reactive protein with components of the metabolic syndrome in normal-weight and overweight elderly

BACKGROUND AND AIM

C-reactive protein (CRP) is known to be elevated in the metabolic syndrome. We aimed to explore in more detail the relationship between CRP and other components of the metabolic syndrome in a general population of 605 Dutch elderly individuals aged 65-84 years.

METHODS AND RESULTS

Data were collected on body mass index (BMI), plasma CRP, plasma plasminogen activator inhibitor 1 (PAI-1), serum insulin, serum lipids, blood pressure, lifestyle and medical history. CRP was log-transformed (ln-CRP) to improve normality. Associations of ln-CRP with components of the metabolic syndrome were studied by multivariate linear regression analysis, in strata of gender and overweight status, with adjustment for age, physical activity, and smoking habits. A total of 322 subjects (53%) were overweight (BMI > or =25 kg/m2).

CONCLUSIONS

In normal-weight women, ln-CRP was significantly associated with BMI, PAI-1, serum insulin, and HDL-cholesterol. In overweight women, however, these relationships were weak and not statistically significant. Findings were similar in men, although less pronounced than in women. Our data suggest that the role of CRP in the metabolic syndrome is modified by the amount of body fat.

Genetic variation in Fcgamma receptor IIa protects against advanced peripheral atherosclerosis. The Rotterdam Study

Immune processes play a substantial role in atherosclerotic disease. The role in atherosclerosis of Fcgamma receptor IIa (FcgammaRIIa), a receptor for immunoglobulin G and for the inflammatory mediator C-reactive protein, is not yet clear. Since the R/H131 polymorphism in the FcgammaRIIa gene strongly influences binding to FcgammaRIIa, we investigated the association of the R/H131 polymorphism with advanced peripheral atherosclerosis. Within the Rotterdam Study, a population-based cohort study, we determined FcgammaRIIa genotype in 430 subjects with advanced peripheral atherosclerosis as indicated by the ankle-arm index, and 411 controls. Heterozygous and homozygous carriers of the H131 allele were protected against advanced peripheral atherosclerosis (age- and gender-adjusted odds ratio (OR) 0.77 (0.54-1.12) and 0.65 (0.44-0.98), respectively, P trend=0.04). This effect was most pronounced in subjects with modestly elevated levels of inflammation as indicated by the leukocyte count (OR 0.52 (0.29-0.93) and 0.45 (0.23-0.86), for heterozygotes and H131 homozygotes, respectively; P trend=0.02). This is the first study showing that the H131 allele of FcgammaRIIa protects against advanced peripheral atherosclerosis.

Report on the Dutch consensus development meeting for implementation and further development of population screening for colorectal cancer based on FOBT

A consensus development meeting was held to evaluate whether or not in the Netherlands all requirements were fulfilled for implementation of population screening with FOBT for colorectal cancer, or whether consensus was present that fulfilment by additional research or organisational actions could be obtained within 2-3 years. There was consensus that all classical Wilson and Jungner (1968) criteria, and six additional ones added more recently, had already been fulfilled or could be fulfilled within 2-3 years. Consequently, it was concluded that a national population screening for colorectal cancer should be implemented and carried out in the Netherlands in line with current national and European cancer screening programmes. A list of organisational actions to be taken was established. Research that is needed before the actual national launch of the screening within 2-3 years has been defined. Priorities have to be set for research and organisational actions for the coming 2-3 years for the implementation of population screening. In addition, research suggestions have been defined for the next 10-15 years for evaluation and/or improvement of implemented FOBT screening, and for future screening methodology. It was considered essential that infrastructure for future research would be embedded in the screening programme. A project group to arrange this should be formed.

No effect of folic acid supplementation in the course of 1 year on haemostasis markers and C-reactive protein in older adults

Elevated homocysteine levels are associated with an increased cardiovascular disease (CVD) risk, but the underlying mechanism is still unclear. High homocysteine might affect the endothelium, and consequently lead to impaired haemostasis. In a randomized placebo controlled trial among 276 older adults with plasma total homocysteine concentrations above 13 mM at screening, we investigated the effect of homocysteine lowering by folic acid supplementation (0.8 mg/day) for 1 year on markers of endothelial function (von Willebrand factor), coagulation (tissue factor, factor VIIa, fragments 1+2), and fibrinolysis (fibrin degradation products, tissue-type plasminogen activator), and inflammation (C-reactive protein). Despite a 24% reduction in plasma homocysteine concentration and four-fold increase in serum folate concentration in the folic acid group compared to the placebo group, there was no clear change in any of the haemostasis markers, nor CRP. Although homocysteine is associated with vascular disease risk in the general population, marked lowering of slightly elevated homocysteine concentrations by one-year folic acid supplementation does not influence haemostasis markers.

The fibrinolytic system and thrombotic tendency

The deposition of the insoluble protein matrix, fibrin is temporary. The mainly known mechanism of proteolytic removal is orchestrated by a cascade type of proteolytic process involving ultimately the formation from plasminogen of the active degradation enzyme plasmin. The occurrence of plasminogen deficiency without a massive deposition of fibrin and thrombotic events indicates the occurrence of alternate routes of fibrin degradation. In the literature, data have been reported about the direct fibrinolytic activity of various other enzymes including leucocytal elastase and cathepsin G and three metalloproteinases (MMP-3,MMP-7, MT1-MMP). The importance of each of these pathways and the possible differences in importance in various diseases, in acute situations and at different locations in the circulation, in tissues and organs is not known in detail. It is suggested that multiple combined knock-outs be created to evaluate the situation for various well-defined phenotypes. It is concluded that fibrin removal is an important biological process with various buffering mechanisms and only combinations of abnormalities in the various mechanisms and special situations will lead to fibrin accumulation and thrombotic events.

Intake of n-3 fatty acids from fish does not lower serum concentrations of C-reactive protein in healthy subjects

OBJECTIVE

High-sensitivity C-reactive protein (CRP), a marker of systemic inflammation, is a powerful predictor of cardiovascular risk. We hypothesised that n-3 fatty acids reduce underlying inflammatory processes and consequently CRP concentrations in healthy middle-aged subjects.

DESIGN

Placebo-controlled, double-blind study.

SUBJECTS

A total of 43 men and 41 postmenopausal women aged 50-70 y. Before and after intervention, we measured serum CRP concentrations with an enzyme immunoassay.

INTERVENTIONS

Capsules with either 3.5 g/day fish oil (1.5 g/day n-3 fatty acids) or placebo for 12 weeks.

RESULTS

The median CRP change in the fish oil group did not significantly differ from that in the placebo group (0.01 vs -0.17 mg/l, P = 0.057).

CONCLUSION

The currently available data--including ours--do not support that beneficial effects on CRP are involved in a mechanism explaining the protective effect on heart disease risk of n-3 fatty acids as present in fish.

Genetics of Dizygotic Twinning: A Feasibility Study for a Biobank

To locate the genes that make a substantial contribution to variation in natural dizygotic twinning in humans, large-scale studies are needed. New studies should not stop at DNA genotyping, but collect material that allow gene-expression analysis, transcriptomics, proteomics and endocrinology. In this article we describe a pilot study to examine the feasibility, effectiveness and logistics of large-scale nationwide sample collection in Dutch families in which two or more sisters have given birth to spontaneous dizygotic twins. Pedigree data and addresses from family members of proband mothers were collected by telephone. Blood and urine samples were collected during a home visit, and handled in the afternoon. All participants were bled between 7 a.m. and 10 a.m. after overnight fasting. Blood samples of fertile women with a natural cycle were collected on the second, third or fourth day of their menstrual cycle. The effects of transportation and storage on blood quality, lipids, RNA with and without challenge, lymphocytes and other parameters were examined. Genomic DNA was isolated from blood and cells were immortalized using Epstein-Barr virus. In 78.6% of the women with a natural cycle blood samples were collected on the second, third or fourth day of the menstrual cycle. This percentage is likely to increase with the more dense geographical distribution of participants in the larger population. We conclude that the pilot study demonstrated the feasibility of this protocol to collect good quality of plasma, DNA, RNA and lymphocyte samples by home visits.

Serum carotenoids and vitamins in relation to markers of endothelial

BACKGROUND

Endothelial cell dysfunction may be related to an increase in cellular oxidative stress. Carotenoids and vitamins could have an antioxidant-mediated tempering influence on endothelial function and inflammation, thereby reducing the risk of atherosclerosis.

METHODS

We measured serum carotenoids, alpha-tocopherol and Vitamin C concentrations in 379 subjects sampled from the general population. High-sensitive C-reactive protein (CRP), fibrinogen (Fbg) and leukocytes were measured as markers of inflammation. Furthermore, soluble intercellular adhesion molecule-1 (sICAM-1) and flow-mediated vasodilation (FMD; n= 165) were measured as markers of endothelial function. Relationships between serum carotenoids and vitamins and markers of endothelial function and inflammation were analysed after adjustment for confounding.

RESULTS

In the total study group, lutein and lycopene were inversely related to sICAM-1 with regression-coefficients of -0.38+/-0.19 (p = 0.04) and -0.16+/-0.08 (p = 0.04) per 1 micromol/l, respectively. beta-Carotene was inverse related to leukocytes (-0.23+/-0.07; p = 0.007) and CRP (-1.09+/-0.30; p = 0.0003) per 1 micromol/l. Vitamin C was inverse related to CRP (-0.01+/-0.005; p = 0.04) per 1 micromol/l, whereas alpha-tocopherol was positively related to CRP (0.03+/-0.01; p = 0.02) per 1 micro/l. Zeaxanthin was inversely related to FMD (31.2+/-15.3; p = 0.04) per 1 micromol/l.

CONCLUSION

The inverse relations between carotenoids, Vitamin C and sICAM-1, CRP and leukocytes may help to explain the possible protective effect of carotenoids and Vitamin C on atherosclerosis through an influence on inflammatory processes and endothelial function.

Combined association and linkage analysis applied to the APOE locus

Combined association and linkage analysis is a powerful tool for pinpointing functional quantitative traits (QTLs) responsible for regions of significant linkage identified in genome-wide scans. We applied this technique to apoE plasma levels and the APOEepsilon2/epsilon3/epsilon4 polymorphism in two Dutch twin cohorts of different age ranges. Across chromosome 19, short tandem repeats and the APOEepsilon2/epsilon3/epsilon4 polymorphism were genotyped in adolescent (aged 13-22 years) and adult (aged 34-62 years) Dutch twins. In both samples, evidence for indicative linkage with plasma apoE levels was found (maximum LOD score (MLS)=0.8, MLS=2.5, respectively) at 19q13.32. These linkage regions included the APOE locus. As expected, the APOEepsilon2/epsilon3/epsilon4 polymorphism was strongly associated with apoE plasma levels in both samples. An extension of the between/within families association test developed by Fulker et al. ([1999] Am. J. Hum. Genet. 64:259-267) showed that these associations were not due to population stratification. The combined association and linkage analyses revealed that the association of the APOEepsilon2/epsilon3/epsilon4 polymorphism with apoE plasma levels completely explained the linkage in the adolescent twins and partly in the adult twins.

Variable Hypocoagulant Effect of Fish Oil Intake in Humans

Objective— The beneficial effect of dietary fish oil, rich in omega-3 polyunsaturated fatty acids (PUFAs), on cardiovascular disease is multifactorial and may partly rely on their anticoagulant action. We studied how fish oil intake influenced thrombin generation in plasma and which factors were involved herein.

Methods and Results— Twenty-five healthy males with borderline overweight received 3.0 g omega-3 PUFAs daily for 4 weeks. Fish oil intake reduced plasma triglycerides and lowered platelet integrin activation, as well as plasma levels of fibrinogen and factor V, but had no effect on vitamin K-dependent coagulation factors. Before fish oil intake, thrombin generation (reflecting the coagulant potential) considerably varied between plasmas from individual subjects, which were partly explained by variation in prothrombin, antithrombin, fibrinogen, and factor V levels. Fish oil intake reduced thrombin generation in the presence and absence of platelets. This reduction correlated with the fish oil effect on fibrinogen and factor V levels. Interestingly, the lowering effect of fish oil on thrombin generation and fibrinogen clustered around subjects with high fibrinogen carrying a structural fibrinogen α-chain polymorphism.

Conclusions— Dietary omega-3 PUFAs provoke a hypocoagulant, vitamin K-independent effect in humans, the degree of which may depend on fibrinogen level.

Principles of use of surrogate markers and endpoints

Surrogate end-points are markers of biological mechanisms and require a mechanistic view on diseases. Thus, the validation of candidate surrogate end-points for the cardiovascular risk of sex steroids requires that a separate evaluation be made of the various clinical endpoints in which different biological mechanisms are likely to operate. The case of venous thromboembolic (VTE) disease and arterial diseases is complex since they are multifactorial and multiple surrogate end-points are likely to be relevant. In addition sex steroids have many effects on biological mechanisms and the selection and validation of surrogates from the available bulk of changes in multiple mechanisms is a large enterprise. In addition, the combination of candidates in algorithms is required and at very early development stages only. In practice, the validation of candidates requires the detection of changes or levels achieved in intervention trials with clinical end-points and such evaluations are scarce. The observations of increased risk of VTE for first-time users of sex steroids indicate the occurrence of a susceptible subgroup, suggesting that effects in this group may be dissimilar to those in the population as a whole or quantitatively strongly different.

A comparative study of the effects of gestodene 60 microg/ethinylestradiol 15 microg and desogestrel 150 microg/ethinylestradiol 20 microg on hemostatic balance, blood lipid levels and carbohydrate metabolism

OBJECTIVES

This multicenter, randomized, parallel-group, open-label study was conducted to compare the effects of gestodene (GTD) 60 microg/ethinylestradiol (EE) 15 microg and desogestrel (DSG) 150 microg/EE 20 microg (Mercilon) on selected metabolic measurements during six cycles in 124 healthy women.

METHODS

GTD/EE subjects received a single pill once daily from days 1 to 24 of a 28-day cycle, followed by placebo pills daily for the last 4 days of the cycle. DSG/EE subjects received a single pill daily from days 1 to 21 of a 28-day cycle, followed by a 7-day pill-free interval. Safety was assessed from changes in hemostatic measurements, lipid profile, glucose tolerance and adverse events.

RESULTS

Both GTD/EE and DSG/EE groups exhibited minimal effects on the lipid profile. An increased glucose response was noted with both treatments and an increased insulin response was noted with GTD/EE. Hemostatic activity was increased in both groups but a counteracting increase in fibrinolytic activity occurred together with an increase in coagulatory activity. The incidence of adverse events was comparable between groups, and no significant differences in cycle control were observed between groups. No pregnancies occurred in either group.

CONCLUSIONS

The 24-day GTD 60 microg/EE 15 microg formulation and DSG/EE produced similar effects on hemostatic balance, lipid metabolism and glucose tolerance, and exhibited comparable efficacy and tolerability.