Diurnal, seasonal, and blood-processing patterns in levels of circulating fibrinogen, fibrin D-dimer, C-reactive protein, tissue plasminogen activator, and von Willebrand factor in a 45-year-old population

The differential impact of subjective and objective aspects of social engagement on cardiovascular risk factors

Background

This article provides new insights into the impact of social engagement on CVD risk factors in older adults. We hypothesized that objective (social participation, social ties and marital status) and subjective (emotional support) aspects of social engagement are independently associated with objective measures of cardiovascular risk.

Methods

Data from the English Longitudinal Study on Ageing (ELSA) were analyzed. The effects of social participation, social ties, marital status, and emotional support on hypertension, obesity, high sensitivity C-reactive protein, and fibrinogen were estimated by logistic regression controlling for age, sex, education, physical function, depression, cardiovascular disease, other chronic diseases, physical activity, and smoking.

Results

Social participation is a consistent predictor of low risk for four risk factors, even after controlling for a wide range of covariates. Being married is associated with lower risk for hypertension. Social ties and emotional support are not significantly associated with any of the cardiovascular risk factors.

Conclusion

Our analysis suggests that participation in social activities has a stronger association with CV risk factors than marital status, social ties or emotional support. Different forms of social engagement may therefore have different implications for the biological risk factors involved.

Long-term effects on haemostatic variables of three ad libitum diets differing in type and amount of fat and carbohydrate: a 6-month randomised study in obese individuals

Diet is important in the prevention of CVD, and it has been suggested that a diet high in MUFA is more cardioprotective than a low-fat diet. We hypothesised that the thrombotic risk profile is improved most favourably by a high-MUFA diet compared with a low-fat diet. This was tested in a parallel randomised intervention trial on overweight individuals (aged 28·2 (sd 4·6) years) randomly assigned to a diet providing a moderate amount of fat (35–45 % of energy; >20 % of fat as MUFA) (MUFA diet; n 39), to a low-fat (LF; 20–30 % of energy) diet (n 43), or to a control diet (35 % of energy as fat; n 24) for 6 months after a weight loss of about 10 %. Protein constituted 10–20 % of energy in all three diets. All foods were provided free of charge from a purpose-built supermarket. Fasting blood samples were collected before and after intervention and analysed for factor VII coagulant activity (FVII:c), fibrinogen, prothrombin fragment 1+2 (F1+2), D-dimer and plasminogen activator inhibitor (PAI). The fibrinogen concentration was significantly lowered by the LF diet, but not by the MUFA diet. Changes in fibrinogen differed significantly between diet groups. BMI and PAI concentration increased and D-dimer concentrations were reduced irrespective of the diets. No changes were observed for FVII:c and F1+2. Our findings suggest that in overweight subjects after weight loss the thrombotic risk profile is improved most favourably by the LF diet compared with the MUFA diet based on the reduction in fibrinogen concentrations.

Novel associations of multiple genetic loci with plasma levels of factor VII, factor VIII, and von Willebrand factor: The CHARGE (Cohorts for Heart and Aging Research in Genome Epidemiology) Consortium

BACKGROUND

Plasma levels of coagulation factors VII (FVII), VIII (FVIII), and von Willebrand factor (vWF) influence risk of hemorrhage and thrombosis. We conducted genome-wide association studies to identify new loci associated with plasma levels.

METHODS AND RESULTS

The setting of the study included 5 community-based studies for discovery comprising 23 608 European-ancestry participants: Atherosclerosis Risk In Communities Study, Cardiovascular Health Study, British 1958 Birth Cohort, Framingham Heart Study, and Rotterdam Study. All subjects had genome-wide single-nucleotide polymorphism (SNP) scans and at least 1 phenotype measured: FVII activity/antigen, FVIII activity, and vWF antigen. Each study used its genotype data to impute to HapMap SNPs and independently conducted association analyses of hemostasis measures using an additive genetic model. Study findings were combined by meta-analysis. Replication was conducted in 7604 participants not in the discovery cohort. For FVII, 305 SNPs exceeded the genome-wide significance threshold of 5.0x10(-8) and comprised 5 loci on 5 chromosomes: 2p23 (smallest P value 6.2x10(-24)), 4q25 (3.6x10(-12)), 11q12 (2.0x10(-10)), 13q34 (9.0x10(-259)), and 20q11.2 (5.7x10(-37)). Loci were within or near genes, including 4 new candidate genes and F7 (13q34). For vWF, 400 SNPs exceeded the threshold and marked 8 loci on 6 chromosomes: 6q24 (1.2x10(-22)), 8p21 (1.3x10(-16)), 9q34 (<5.0x10(-324)), 12p13 (1.7x10(-32)), 12q23 (7.3x10(-10)), 12q24.3 (3.8x10(-11)), 14q32 (2.3x10(-10)), and 19p13.2 (1.3x10(-9)). All loci were within genes, including 6 new candidate genes, as well as ABO (9q34) and VWF (12p13). For FVIII, 5 loci were identified and overlapped vWF findings. Nine of the 10 new findings were replicated.

CONCLUSIONS

New genetic associations were discovered outside previously known biological pathways and may point to novel prevention and treatment targets of hemostasis disorders.

Day/Night rhythm of hemostatic factors in obstructive sleep apnea

STUDY OBJECTIVES

To investigate the hypothesis that day/night patterns of prothrombotic activity differ between patients with obstructive sleep apnea (OSA) and individuals with no OSA.

DESIGN

Prothrombotic markers' day/night rhythms recorded over one 24-h period.

SETTING

General clinical research center.

PATIENTS

38 untreated OSA patients as verified by polysomnography (apnea-hypopnea index > or = 10/h sleep) and 22 non-OSA controls.

MEASUREMENTS AND RESULTS

Blood samples were collected every 2 h to measure plasma levels of fibrinolysis-inhibiting plasminogen activator inhibitor (PAI)-1 and the primary fibrin degradation product D-dimer. Day/night variation in hemostasis factors was examined using a cosinor analysis. Mesor (mean) PAI-1 over the 24-h period was higher (P = 0.015), and mesor of D-dimer was lower (P = 0.001) in patients with OSA than in the non-OSA controls. These group differences stayed significant when controlling for age and gender. After further adjustment for body mass index, mean arterial pressure, and smoking, the relationship between OSA and PAI-1 became non-significant, but the relationship between OSA and D-dimer continued to be significant (P = 0.006). In the fully adjusted analysis, the amplitude (peak) for D-dimer was lower in OSA patients than in non-OSA controls (P = 0.048). The acrophase (time of the peak) for PAI-1 and D-dimer did not significantly differ between groups.

CONCLUSIONS

The relatively higher average level of PAI-1 and lower average level of D-dimer across the 24-h in OSA patients might reflect decreased fibrinolytic capacity and fibrin degradation, respectively. The findings provide some evidence for a prothrombotic state in OSA, but were only partially independent of metabolic variables.

Sleep and biomarkers of atherosclerosis in elderly Alzheimer caregivers and controls

BACKGROUND

Perturbed sleep might contribute to cardiovascular disease by accelerating atherosclerosis. Sleep is poor in Alzheimer caregivers who are also a group at increased cardiovascular risk.

OBJECTIVE

To test the hypothesis that impaired sleep relates to elevated levels of biomarkers of atherosclerosis in community-dwelling elderly and that this association would possibly be stronger in caregivers than in non-caregiving controls.

METHODS

We studied 97 Alzheimer caregivers and 48 non-caregiving controls (mean age 71 +/- 8 years, 72% women) who underwent wrist actigraphy at their homes. Measures of objective sleep were averaged across 3 consecutive nights. The Pittsburgh Sleep Quality Index was administered by an interviewer to rate subjective sleep quality. Morning fasting blood samples were collected to determine measures of inflammation, coagulation and endothelial dysfunction.

RESULTS

There were independent associations between decreased subjective sleep quality and increased levels of fibrin D-dimer (p = 0.022, DeltaR(2) = 0.029) and von Willebrand factor antigen (p = 0.029, DeltaR(2) = 0.034) in all participants. Percent sleep (p = 0.025) and subjective sleep quality (p = 0.017) were lower in caregivers than in controls. In caregivers, the correlation between decreased percent sleep and elevated levels of interleukin-6 (p = 0.042, DeltaR(2) = 0.039) and C-reactive protein (p < 0.10, DeltaR(2) = 0.027) was significantly stronger than in controls.

CONCLUSION

Perceived impairment in sleep related to increased coagulation activity and endothelial dysfunction in all participants, whereas objectively impaired sleep related to inflammation activity in caregivers. The findings provide one explanation for the increased cardiovascular risk in elderly poor sleepers and dementia caregivers in particular.

CRP identifies homeostatic immune oscillations in cancer patients: a potential treatment targeting tool?

The search for a suitable biomarker which indicates immune system responses in cancer patients has been long and arduous, but a widely known biomarker has emerged as a potential candidate for this purpose. C-Reactive Protein (CRP) is an acute-phase plasma protein that can be used as a marker for activation of the immune system. The short plasma half-life and relatively robust and reliable response to inflammation, make CRP an ideal candidate marker for inflammation. The high- sensitivity test for CRP, termed Low-Reactive Protein (LRP, L-CRP or hs-CRP), measures very low levels of CRP more accurately, and is even more reliable than standard CRP for this purpose. Usually, static sampling of CRP has been used for clinical studies and these can predict disease presence or recurrence, notably for a number of cancers. We have used frequent serial L-CRP measurements across three clinical laboratories in two countries and for different advanced cancers, and have demonstrated similar, repeatable observations of a cyclical variation in CRP levels in these patients. We hypothesise that these L-CRP oscillations are part of a homeostatic immune response to advanced malignancy and have some preliminary data linking the timing of therapy to treatment success. This article reviews CRP, shows some of our data and advances the reasoning for the hypothesis that explains the CRP cycles in terms of homeostatic immune regulatory cycles. This knowledge might also open the way for improved timing of treatment(s) for improved clinical efficacy.

Nighttime vagal cardiac control and plasma fibrinogen levels in a population of working men and women

BACKGROUND

Elevated plasma fibrinogen levels have prospectively been associated with an increased risk of coronary artery disease in different populations. Plasma fibrinogen is a measure of systemic inflammation crucially involved in atherosclerosis. The vagus nerve curtails inflammation via a cholinergic antiinflammatory pathway. We hypothesized that lower vagal control of the heart relates to higher plasma fibrinogen levels.

METHODS

Study participants were 559 employees (age 17-63 years; 89% men) of an airplane manufacturing plant in southern Germany. All subjects underwent medical examination, blood sampling, and 24-hour ambulatory heart rate recording while kept on their work routine. The root mean square of successive differences in RR intervals during the night period (nighttime RMSSD) was computed as the heart rate variability index of vagal function.

RESULTS

After controlling for demographic, lifestyle, and medical factors, nighttime RMSSD explained 1.7% (P = 0.001), 0.8% (P = 0.033), and 7.8% (P = 0.007), respectively, of the variance in fibrinogen levels in all subjects, men, and women. Nighttime RMSSD and fibrinogen levels were stronger correlated in women than in men. In all workers, men, and women, respectively, there was a mean +/- SEM increase of 0.41 +/- 0.13 mg/dL, 0.28 +/- 0.13 mg/dL, and 1.16 +/- 0.41 mg/dL fibrinogen for each millisecond decrease in nighttime RMSSD.

CONCLUSIONS

Reduced vagal outflow to the heart correlated with elevated plasma fibrinogen levels independent of the established cardiovascular risk factors. This relationship seemed comparably stronger in women than men. Such an autonomic mechanism might contribute to the atherosclerotic process and its thrombotic complications.

Plasma CRP levels in premenopausal women with major depression: a 12-month controlled study

C-reactive protein (CRP), an inflammatory marker of cardiovascular risk, is often elevated in major depressive disorder (MDD). The magnitude and consistency of this elevation have not been previously characterized in premenopausal women with MDD. The aim of the study was to prospectively assess plasma CRP levels, body composition, endocrine and metabolic parameters, and depressive status in premenopausal women with MDD (n=77) and controls (n=41), aged 21 to 45. Women were enrolled in a 12-month, controlled study of bone turnover, the P.O.W.E.R. ( Premenopausal, Osteoporosis, Women, Al Endronate, Dep Ression) Study. Blood samples were taken at Baseline, Month 6, and Month 12. Most subjects with MDD were in clinical remission. These women tended to have consistently higher CRP levels than controls over 12 months (p=0.077). BMI was positively related to log[CRP] in women with MDD only. Nine women with MDD had CRP levels greater than 10 mg/l, a value associated with a very high cardiovascular risk. This subset was obese and had significantly higher triglycerides, total cholesterol, LDL-cholesterol, fasting insulin, and HOMA-IR than the rest of women with MDD. The variations in CRP levels over time were high (intra- and inter-individual coefficients of variations of approximately 30-50% and approximately 70-140%, respectively). No control had CRP levels greater than 10 mg/l. Depression was associated with increased plasma CRP in women with MDD. The clinical significance of abnormal plasma CRP for cardiovascular risk needs to be assessed in large prospective studies of women with depression.

Daily family assistance and inflammation among adolescents from Latin American and European backgrounds

To assess the biological impact of time spent helping the family during the teenage years, we examined circulating levels of interleukin-6 (IL-6), soluble interleukin-6 receptor (sIL-6r), and C-reactive protein (CRP) in 64 adolescents (M(age)=17.79 years) from Latin American and European backgrounds. Analyses of nightly diary checklists over 14 days showed that the amount of time spent helping the family in a variety of ways, such as cooking, cleaning, and sibling care, was associated with long-term elevations of sIL-6r and CRP, even after controlling for ethnicity, parental education, BMI, substance use, distress, and frequency of daily family assistance 2 years earlier. However, adolescents who derived a greater sense of role fulfillment from helping the family on a daily basis had lower levels of sIL-6r and CRP as compared to their peers who engaged in the same amount of family assistance. Additional work should explore the family context that drives high levels of assistance among adolescents, as well as the variety of ways adolescents may derive meaning from this activity.

Association of vital exhaustion and depressive symptoms with changes in fibrin D-dimer to acute psychosocial stress

OBJECTIVE

Vital exhaustion and depression are psychosocial risk factors of coronary artery disease. A hypercoagulable state in response to acute psychosocial stress contributes to atherothrombotic events. We aimed to investigate the hypothesis that vital exhaustion and depression correlate with stress-induced changes in the hypercoagulability marker D-dimer.

METHODS

Thirty-eight healthy and nonsmoking school teachers (mean age 50+/-8 years, 55% women) completed the nine-item Maastricht Vital Exhaustion Questionnaire and the seven-item depression subscale of the Hospital Anxiety and Depression Scale. Within 1 week, subjects twice underwent the Trier Social Stress Test (i.e., preparation phase, mock job interview, and mental arithmetic that totaled 13 min). Plasma D-dimer levels were determined at five time points during the protocol.

RESULTS

Vital exhaustion (P=.022; eta(2)=.080) and depressive symptoms (P=.011; eta(2)=.090) were associated with stress-induced changes in D-dimer levels over time controlling for sex and age. Elevated levels of vital exhaustion (r=-.46, P=.005) and of depression (r=-.51, P=.002) correlated with reduced D-dimer increase from pre-stress to immediately post-stress. Also, elevated vital exhaustion (r=.34, P=.044) and depression (r=.41, P=.013) were associated with increase (i.e., attenuated recovery) of D-dimer levels between 20 and 45 min post-stress. Controlling for stress hormone and blood pressure reactivity did not substantially alter these results.

CONCLUSION

The findings suggest an attenuated immediate D-dimer stress response and delayed recovery of D-dimer levels post-stress with elevated vital exhaustion and depressive symptoms. In particular, the prolonged hypercoagulability after stress cessation might contribute to the atherothrombotic risk previously observed with vital exhaustion and depression, even at subclinical levels.

Chronic exposure to outdoor air pollution and markers of systemic inflammation

BACKGROUND

Cohort studies suggest that long-term exposure to higher levels of outdoor air pollution increases risk of developing cardiovascular disease. One suggested mechanism is that air pollution, especially particulate matter, induces systemic inflammation, thereby increasing the risk of developing long-term pathologic changes in the cardiovascular system, We aimed to examine the association between long-term exposure to higher levels of air pollution and chronic systemic inflammation.

METHODS

We examined the relationship between 2 markers of systemic inflammation (fibrinogen and C-reactive protein) and measures of outdoor air pollution estimated for each postcode sector of residence, using models incorporating information on pollutant emissions from multiple sources, and atmospheric dispersion and processing, in 3 representative cross-sectional studies of the English population in 1994, 1998, and 2003. These included about 25,000 adults with fibrinogen measurements and 17,000 adults with C-reactive protein measurements. We used multilevel linear regression modeling and pooled the results from the 3 surveys using meta-analysis.

RESULTS

We found no associations between concentrations of fibrinogen or C-reactive protein and measures of outdoor air pollution (particulate matter <10 mum in diameter (PM10), nitrogen dioxide, sulfur dioxide, and ozone). Specifically, we found, for each 1-microg/m(3) [corrected] increase in PM(10) concentration, a change in fibrinogen concentrations of -0.08% (95% confidence interval = -0.25 to [corrected] 0.10) and in C-reactive protein concentrations of 0.14% (-1.00 to [corrected] 1.30).

CONCLUSIONS

Our findings do not support the hypothesis that the association between outdoor air pollution exposure and later cardiovascular disease is mediated by chronic systemic inflammation.

Comparative value of simple inflammatory markers in the prediction of left ventricular systolic dysfunction in postacute coronary syndrome patients

Objectives. We sought to assess the comparative value of inflammatory markers on the occurrence of left ventricular systolic dysfunction (LVSD) after an acute coronary syndrome (ACS). Methods. During 2006–2008, 760 patients with an ACS were enrolled. C-reactive protein (CRP) and white blood cell (WBC) count were measured during the first 12 hours of hospital admission. Results. CRP levels and WBC count were significantly higher in those who developed LVSD compared to those who did not. The analysis revealed that a 10 mg/dL increase of CRP levels and a 1000/μL increase in WBC are associated with a 6% and a 7% increase in the likelihood of developing LVSD, respectively. Furthermore, WBC count at entry and CRP have almost the same predictive value for development of LVSD after an ACS (R² = 0.109 versus R² = 0.093). Conclusions. Serum CRP levels and WBC count at entry are almost equally powerful independent predictors of LVSD, after an ACS.

Association between longitudinal changes in depressive symptoms and plasma fibrinogen levels in school teachers

Depression and anxiety previously predicted coronary artery disease (CAD) risk. Inflammation contributes to CAD and shows an association with depression. We followed 57 teachers (mean 49+/-8 years) over 21 months and investigated whether changes in depressive and anxiety symptoms relate to those in the CAD risk and inflammation marker fibrinogen and vice versa. Increase in depressive symptoms and in fibrinogen levels were significantly correlated. While controlling for baseline depression rendered the association between changes in depression and fibrinogen nonsignificant, taking into account baseline fibrinogen levels maintained the predictive value of fibrinogen change for depression change. Anxiety and fibrinogen changes were not significantly correlated. This dynamic relationship between depression and the inflammatory biomarker fibrinogen might advance our knowledge about psychobiological mechanisms underlying both CAD and sickness behavior.

Seasonal and sex variation of high-sensitivity C-reactive protein in healthy adults: a longitudinal study

BACKGROUND

Cross-sectional studies have reported seasonal variation in high-sensitivity C-reactive protein (hsCRP). However, longitudinal data are lacking.

METHODS

We collected data on diet, physical activity, psychosocial factors, physiology, and anthropometric measurements from 534 healthy adults (mean age 48 years, 48.5% women, 87% white) at quarterly intervals over a 1-year period between 1994 and 1998. Using sinusoidal regression models, we estimated peak-to-trough amplitude and phase of the peaks.

RESULTS

At baseline, average hsCRP was 1.72 mg/L (men, 1.75 mg/L; women, 1.68 mg/L). Overall seasonal variation amplitude was 0.16 mg/L (95% CI 0.02 to 0.30) and was lower in men (0.10 mg/L, 95% CI -0.11 to 0.31) than in women (0.23 mg/L, 95% CI 0.04 to 0.42). In both sexes, hsCRP peaked in November, with a corresponding trough in May. Relative plasma volume, waist and hip circumference, diastolic blood pressure, and depression scores were major factors associated with changes in amplitude of seasonal variation of hsCRP, and taken together explain most of the observed seasonal change. There was a 20% increase in the percentage of participants classified in the high-risk category for hsCRP (> or =3 mg/L) during late fall and early winter compared with late spring and early summer.

CONCLUSIONS

Concentrations of hsCRP were modestly increased in fall and winter compared to summer, with greater seasonal amplitude of variation observed in women. Conventional classification methods fail to consider seasonality in hsCRP and may result in substantial misclassifications in the spring and fall. Future clinical practice and research should take these variations into account.

Effects of low ambient temperature on heart rate variability during sleep in humans

The effects of cold exposure on heart rate variability (HRV) during sleep were examined. Eight male subjects slept under three different conditions: 3 degrees C, 50-80% relative humidity (RH) [3]; 10 degrees C, 50% RH [10]; and 17 degrees C 50% RH [17]. No significant differences were observed in HRV during rapid eye movement sleep (REM) and wakefulness. The ratio of the low frequency (LF) to high frequency component (HF) of HRV (LF/HF) significantly differed among the conditions during stage 2 and slow wave sleep (SWS) that decreased as the ambient temperature decreased. The normalized LF [LF/(LF + HF)] significantly decreased in 3 and 10 than in 17 during SWS. In low ambient temperature, predominant cardiac parasympathetic activity during stage 2 with no significant difference during REM and wakefulness may cause variations in HRV at transition from stage 2 to REM and wakefulness. These results may partly explain the peak in adverse cardiac events during winter.

Effects of time of collection and sample processing on von Willebrand factor concentration in retired racing greyhounds

BACKGROUND

Concentrations of von Willebrand factor (vWF) are less than 30% in approximately 10% of Greyhounds.

HYPOTHESIS

That sample collection, processing, and storage can affect the concentration of vWF in plasma of Greyhounds.

ANIMALS

Nineteen healthy former racing Greyhounds.

METHODS

Prospective study: Blood samples were obtained from the jugular vein of dogs at 4 times during the day. Samples were divided and processed in each of 3 ways. The 1st tube was centrifuged immediately, the 2nd tube was kept in a household refrigerator, and the 3rd tube was kept at room temperature for 3 hours before centrifugation and processing.

RESULTS

There were no significant differences in the vWF concentration between different sample storage and processing (P = 5.31). There was no statistically significant diurnal variation in vWF concentration in the samples evaluated (P = .37).

CONCLUSIONS AND CLINICAL IMPORTANCE

Time of sample collection and short-term storage temperature do not influence the vWF concentration in retired racing Greyhounds.

Centrally located body fat is related to inflammatory markers in healthy postmenopausal women

OBJECTIVE

C-reactive protein and fibrinogen are established atherosclerotic cardiovascular disease risk factors. These acute-phase proteins and the proinflammatory cytokines tumor necrosis factor alpha, interleukin-6, and interleukin-1beta may be elevated in obesity and with menopause. The purpose of this multicenter study was to identify whether centrally located fat and/or overall adiposity were related to these inflammatory markers in healthy postmenopausal women.

DESIGN

We used dual-energy x-ray absorptiometry to assess overall and regional body composition (fat mass in particular) in 242 postmenopausal women in relation to plasma fibrinogen, serum C-reactive protein, and these proinflammatory cytokines.

RESULTS

Multiple regression analyses revealed that 36% of the variability in C-reactive protein (F = 32.4, P <or= 0.0001) was accounted for by androidal fat mass (16.1%, P <or= 0.0001), white blood cells (5.6%, P <or= 0.0001), and age (2.3%, P = 0.0045). Regression analyses revealed that 30% of the variability in fibrinogen (F = 24.5, P <or= 0.0001) was accounted for by white blood cells (3.1%, P = 0.0015), hip fat mass (2.2%, P = 0.0081), years since menopause (0.9%, P = 0.082), and geographic site (P <or= 0.0001). Our results indicated that androidal fat mass and hip fat mass contributed to C-reactive protein and fibrinogen, respectively, whereas we found no association between whole-body or regional fat measures and cytokines.

CONCLUSION

Further study is warranted to determine the responsiveness of these acute-phase proteins and cytokines to loss of body fat through exercise and dietary intervention in postmenopausal women.

Response of fractional synthesis rate (FSR) of fibrinogen, concentration of D-dimer and fibrinolytic balance to physical activity-based intervention in obese children

BACKGROUND

Physical activity-induced reduction in obesity-related hyperfibrinogenemia in children has been reported. The underlying mechanisms remain elusive. Further, the effect of such interventions on fibrinolysis in children is scarce.

OBJECTIVES

To investigate in obese children, before and after a physical activity-based intervention: (i) the mechanistic role of fractional synthesis rate (FSR) of fibrinogen in the reduction of hyperfibrinogenemia; and (ii) the changes in fibrinolytic factors.

METHODS

Subjects included 21 (age > 14 < 18 years; Tanner stage, IV-V) children (15 obese, BMI >95%tile for age and sex and six lean, BMI <85%tile). After baseline measurements of FSR of fibrinogen, and concentrations of fibrinogen, D-dimer, PAI-1 and t-PA in all children, studies were repeated after a 3-month randomized controlled physical activity-based lifestyle intervention in obese children only.

RESULTS

FSR of fibrinogen was higher (P = 0.002) in the obese (vs. lean) group, which was reduced (P = 0.001) after intervention. This almost completely accounted for the reduction in obesity-related hyperfibrinogenemia. High levels of D-dimer decreased (P = 0.001) after intervention, whereas fibrinolysis was not enhanced.

CONCLUSIONS

The direct reduction in the FSR of fibrinogen and the remarkable correlation between the magnitudes of reduction in fibrinogen FSR and concentration signify a mechanistic role for FSR in the regulation of physical activity-induced reversal of hyperfibrinogenemia in obese children. The congruent reductions in the FSR of fibrinogen and the concentrations of fibrinogen and D-dimer in response to intervention despite depressed fibrinolysis suggest an overall improvement in the hypercoagulable state in obese children with physical activity-based lifestyle intervention.

C-reactive protein, established risk factors and social inequalities in cardiovascular disease - the significance of absolute versus relative measures of disease

Background

The widespread use of relative scales in socioepidemiological studies has recently been criticized. The criticism is based mainly on the fact that the importance of different risk factors in explaining social inequalities in cardiovascular disease (CVD) varies, depending on which scale is used to measure social inequalities. The present study examines the importance of established risk factors, as opposed to low-grade inflammation, in explaining socioeconomic differences in the incidence of CVD, using both relative and absolute scales.

Methods

We obtained information on socioeconomic position (SEP), established risk factors (smoking, hypertension, and hyperlipidemia), and low-grade inflammation as measured by high-sensitive (hs) C-reactive protein (CRP) levels, in 4,268 Swedish men and women who participated in the Malmö Diet and Cancer Study (MDCS). Data on first cardiovascular events, i.e., stroke or coronary event (CE), was collected from regional and national registers. Social inequalities were measured in relative terms, i.e., as ratios between incidence rates in groups with lower and higher SEP, and also in absolute terms, i.e., as the absolute difference in incidence rates in groups with lower and higher SEP.

Results

Those with low SEP had a higher risk of future CVD. Adjustment for risk factors resulted in a rather small reduction in the relative socioeconomic gradient, namely 8% for CRP (≥ 3 mg/L) and 21% for established risk factors taken together. However, there was a reduction of 18% in the absolute socioeconomic gradient when looking at subjects with CRP-levels < 3 mg/L, and of 69% when looking at a low-risk population with no smoking, hypertension, or hyperlipidemia.

Conclusion

C-reactive protein and established risk factors all contribute to socioeconomic differences in CVD. However, conclusions on the importance of "modern" risk factors (here, CRP), as opposed to established risk factors, in the association between SEP and CVD depend on the scale on which social inequalities are measured. The one-sided use of the relative scale, without including a background of absolute levels of disease, and of what causes disease, can consequently prevent efforts to reduce established risk factors by giving priority to research and preventive programs looking in new directions.

Effect of oral melatonin on the procoagulant response to acute psychosocial stress in healthy men: a randomized placebo-controlled study

Acute mental stress is a potent trigger of acute coronary syndromes. Catecholamine-induced hypercoagulability with acute stress contributes to thrombus growth after coronary plaque rupture. Melatonin may diminish catecholamine activity. We hypothesized that melatonin mitigates the acute procoagulant stress response and that this effect is accompanied by a decrease in the stress-induced catecholamine surge. Forty-five healthy young men received a single oral dose of either 3 mg melatonin (n = 24) or placebo medication (n = 21). One hour thereafter, they underwent a standardized short-term psychosocial stressor. Plasma levels of clotting factor VII activity (FVII:C), FVIII:C, fibrinogen, D-dimer, and catecholamines were measured at rest, immediately after stress, and 20 min and 60 min post-stress. The integrated change in D-dimer levels from rest to 60 min post-stress differed between medication groups controlling for demographic and metabolic factors (P = 0.047, eta(p)(2) = 0.195). Compared with the melatonin group, the placebo group showed a greater increase in absolute D-dimer levels from rest to immediately post-stress (P = 0.13; eta(p)(2) = 0.060) and significant recovery of D-dimer levels from immediately post-stress to 60 min thereafter (P = 0.007; eta(p)(2) = 0.174). Stress-induced changes in FVII:C, FVIII:C, fibrinogen, and catecholamines did not significantly differ between groups. Oral melatonin attenuated the stress-induced elevation in the sensitive coagulation activation marker D-dimer without affecting catecholamine activity. The finding provides preliminary support for a protective effect of melatonin in reducing the atherothrombotic risk with acute mental stress.

Common genetic variants associated with plasma fibrin D-dimer concentration in older European- and African-American adults

BACKGROUND AND OBJECTIVES

D-dimer is a hemostasis marker that reflects ongoing fibrin formation and degradation. There is significant inter-individual and inter-population variability in D-dimer concentration, but whether genetic factors underlie these differences is largely unknown. We hypothesized that common coagulation gene variants contribute to differences in circulating D-dimer concentration.

METHODS

The setting was European-American (EA; n = 1858) and African-American (AA; n = 327) unrelated older adults from the Cardiovascular Health Study (CHS), in which we genotyped SNPs in 42 genes related to blood coagulation and fibrinolysis.

RESULTS

Several fibrinogen gene polymorphisms, including the Thr312Ala Aalpha chain variant and the FGG-10034 C/T variant, were associated with approximately 20% higher plasma D-dimer levels in EA (false discovery rate < 5% for covariate-adjusted model). There was also some evidence that a Pro41Leu variant of the PLAU gene encoding urinary plasminogen activator and non-coding polymorphism of the plasminogen activator inhibitor type 1 gene (SERPINE1) were associated with higher plasma D-dimer in EA. There were no significant associations between the studied coagulation or fibrinolysis gene SNPs and plasma D-dimer levels in the smaller AA sample. However, each standard deviation increase in European ancestry assessed by ancestry-informative gene markers was associated with approximately 10% lower mean D-dimer levels in AA.

CONCLUSIONS

Together, common coagulation/fibrinolysis gene SNPs explained only approximately 2% of the variance in plasma D-dimer levels in EA. These findings suggest that the association of D-dimer with risk of vascular outcomes may be mediated largely by environmental factors, other genes, and/or genetic interactions.

Gender-specific and menstrual cycle dependent differences in circulating microparticles

In comparison to age-matched men, young women are at increased risk to suffer from venous thromboembolism (VTE). Some risk factors of inherited and acquired thrombophilia are known, but approximately 30% of the overall risk remains unexplained. Recently, a role for microparticles (MP) in coagulation has been suggested. We investigated, if gender- and menstrual cycle-specific differences in circulating MP exist. Platelet- and endothelial cell-derived microparticles (PMP, EMP) and subpopulations thereof were evaluated flow-cytometrically in healthy women (n = 27) in different phases of their menstrual cycles (follicular phase: n = 14, luteal phase: n = 13) and in healthy men (n = 18). Additionally, D-dimer levels were determined. Compared to men, women had elevated numbers of annexin V-binding MP (p = 0.007), PMP (CD61; p = 0.013), P-selectin-exposing PMP (p = 0.002) and E-selectin-exposing EMP (p = 0.009). During the luteal phase, women had strongly elevated concentrations of MP, PMP, P-selectin- and CD63-exposing PMP as well as E-selectin-exposing EMP (p = 0.001, p < 0.001, p = 0.004, p = 0.003, and p < 0.001, respectively), and the ratio of P-selectin-exposing PMP/platelet increased more than three-fold as compared to men (p = 0.01). When different phases of the menstrual cycle were analysed, MP (annexin V; p = 0.025), PMP (CD61: p < 0.001; CD63: p = 0.015) and E-Selectin-positive EMP (p = 0.006) were all increased in the luteal phase. Although D-dimer concentrations in women were increased compared to men (p = 0 = 0.006), no menstrual cycle-specific differences were observed. In summary, circulating MP and subpopulations thereof are increased in women when compared to men, and this increase seems to be modulated by the menstrual cycle. Therefore, circulating MP may be an additional risk factor contributing to the hitherto unexplained procoagulatory state of young women.

Plasma D-dimer concentration in patients with systemic sclerosis

BACKGROUND

It has been reported that increased plasma D-dimer is a reliable marker of systemic prothrombotic state in patients with cardiovascular diseases.

OBJECTIVES

To evaluate plasma D-dimer concentration in patients with systemic sclerosis (SSc) and healthy controls. We also investigated a possible relationship between the presence of a high plasma D-dimer concentration and clinical and biological parameters in patients with SSc.

METHODS

Measurements of plasma D-dimer concentration were performed in 69 consecutive patients with SSc and 69 age- and sex-matched controls. Clinical and biological findings were compared between patients with and without a high concentration of plasma D-dimer (i.e. >or=500 ng mL(-1)).

RESULTS

Median plasma D-dimer concentrations appeared significantly increased in patients with SSc compared with control subjects (506 vs. 211 ng mL(-1); P<0.001). Furthermore, a high concentration of plasma D-dimer (>or=500 ng mL(-1)) was detected more frequently in patients with SSc than in healthy controls (47.8% vs. 4.5%; P<0.0001). Among vascular manifestations related to SSc, macrovascular impairment responsible for peripheral ischaemia was more frequent in patients with SSc with high levels of D-dimer (>or=500 ng mL(-1)), compared with those without (21% vs. 6%; P=0.05).

CONCLUSIONS

The association between high levels of plasma D-dimer (>or=500 ng mL(-1)) and macrovascular involvement in patients with SSc is likely to be an innovative issue. We suggest that D-dimer levels may be a helpful additional test to identify patients with SSc at risk to develop thrombotic arterial complications (peripheral arterial disease, stroke and coronary event); such patients with high levels of plasma D-dimer (>or=500 ng mL(-1)) may require close monitoring of vascular parameters, including especially macrovascular impairment.