The role of fibrinogen as a cardiovascular risk factor

Age-dependent seasonality in the incidence of stroke: A 21-year population-based study

INTRODUCTION

Seasonality in the incidence of stroke has been examined in numerous studies, yet data on whether it differs with age are limited. To fill this gap, we utilized a largescale dataset from Israel.

PATIENTS AND METHODS

We retrieved data of all hospitalizations for ischemic stroke (IS), transient ischemic attack (TIA) and intra cerebral hemorrhage (ICH) from 2000 to 2020. We maintained separate datasets for IS/TIA and ICH, divided into five age groups: 18-49, 50-59, 60-69, 70-79, and 80+. We modeled the monthly incidence using a generalized additive model. The seasonal effect was defined by the rate ratio (RR) of each month compared to the annual mean.

RESULTS

The analysis included 317,586 and 23,789 events of IS/TIA and ICH respectively. We found an interaction between age and seasonality, accounting for a phase shift with age in the seasonal pattern of IS/TIA incidence. For cases under 70 years, the peak was during summertime and the RRs increased with decreasing age, reaching 1.11 (95% CI 1.09-1.13) at the youngest age group. In contrast, among the elderly, a winter peak was observed and the RRs increased with age to 1.07 (95% CI 1.06-1.08) at the oldest age group. For ICH, a winter/autumn peak was identified and the RRs increased with age to 1.20 (95% CI 1.16-1.24).

CONCLUSIONS

Our finding of age-dependent seasonal patterns in the occurrence of stroke, suggests closer monitoring of cardiovascular risk factors during wintertime among elderly individuals. The mechanism governing the seasonal phase shift with age in IS/TIA incidence, requires further investigation.

Associations Between 25-Hydroxyvitamin D and Total and γ' Fibrinogen and Plasma Clot Properties and Gene Interactions in a Group of Healthy Black South African Women

The role of 25-hydroxyvitamin D [25(OH)D] in reducing the risk of cardiovascular disease (CVD) has been recognized, but the mechanisms involved are unclear. Researchers have discovered a link between vitamin D and fibrinogen. Until now, data on the relationship between vitamin D and the γ' splice variant of fibrinogen and fibrin clot characteristics remain unexplored. In this study, 25(OH)D, total and γ' fibrinogen, as well as turbidimetrically determined plasma clot properties, were quantified, and fibrinogen and FXIII SNPs were genotyped in 660 Black, apparently healthy South African women. Alarmingly, 16 and 45% of the women presented with deficient and insufficient 25(OH)D, respectively. Total fibrinogen and maximum absorbance (as a measure of clot density) correlated inversely, whereas γ' fibrinogen correlated positively with 25(OH)D. γ' fibrinogen increased whereas maximum absorbance decreased over the deficient, insufficient, and sufficient 25(OH)D categories before and after adjustment for confounders. 25(OH)D modulated the association of the SNPs regarding fibrinogen concentration and clot structure/properties, but did not stand after correction for false discovery rate. Because only weak relationships were detected, the clinical significance of the findings are questionable and remain to be determined. However, we recommend vitamin D fortification and supplementation to reduce the high prevalence of this micronutrient deficiency and possibly to improve fibrinogen and plasma clot structure if the relationships are indeed clinically significant. There is a need for large cohort studies to demonstrate the relationship between vitamin D and cardiovascular and inflammatory risk factors as well as to uncover the molecular mechanisms responsible.

Magnesium Sulfate Improves Some Risk Factors for Atherosclerosis in Patients Suffering from One or Two Coronary Artery Diseases: A Double-blind Clinical Trial Study

Purpose

Given the beneficial effect of MgSO₄ on the cardiovascular system, this study was designed to investigate the effect of MgSO₄ administration on suppressing some atherosclerotic risk factors in moderate coronary artery disease patients with one or two atherosclerotic vessels.

Patients and Methods

In a randomized double-blind placebo-controlled clinical trial study, 64 patients with moderate coronary artery disease (55–69% stenosis) were selected according to angiography findings. Patients were divided into four groups including patients with one or two atherosclerotic vessels treated with MgSO₄ (Mg-treated-VR1, Mg-treated-VR2, respectively), placebo treated patients with one or two atherosclerotic vessels (Control-VR1, Control-VR2, respectively). The patients received either placebo or MgSO₄ supplement capsule containing 300 mg MgSO₄ for six months on a daily basis. ESR, Ca/Mg ratio, urine Mg level, serum Mg, fibrinogen, homocysteine, uric acid, Na, K, Ca, CRP, T3, T4, TSH, BUN, and Cr concentrations were measured at baseline and every three months.

Results

Serum T3, Ca, K, homocysteine, CRP, and Mg concentrations were significantly improved in Mg-treated groups compared to placebo groups.

Conclusion

The results of this study showed that despite the slight change in serum magnesium level, oral administration of MgSO₄for six months could slightly reduce the serum levels of some inflammatory and vascular factors in moderate coronary artery disease patients.

Novel Approaches to Air Pollution Exposure and Clinical Outcomes Assessment in Environmental Health Studies

An accurate assessment of pollutants’ exposure and precise evaluation of the clinical outcomes pose two major challenges to the contemporary environmental health research. The common methods for exposure assessment are based on residential addresses and are prone to many biases. Pollution levels are defined based on monitoring stations that are sparsely distributed and frequently distanced far from residential addresses. In addition, the degree of an association between outdoor and indoor air pollution levels is not fully elucidated, making the exposure assessment all the more inaccurate. Clinical outcomes’ assessment, on the other hand, mostly relies on the access to medical records from hospital admissions and outpatients’ visits in clinics. This method differentiates by health care seeking behavior and is therefore, problematic in evaluation of an onset, duration, and severity of an outcome. In the current paper, we review a number of novel solutions aimed to mitigate the aforementioned biases. First, a hybrid satellite-based modeling approach provides daily continuous spatiotemporal estimations with improved spatial resolution of 1 × 1 km2 and 200 × 200 m2 grid, and thus allows a more accurate exposure assessment. Utilizing low-cost air pollution sensors allowing a direct measurement of indoor air pollution levels can further validate these models. Furthermore, the real temporal-spatial activity can be assessed by GPS tracking devices within the individuals’ smartphones. A widespread use of smart devices can help with obtaining objective measurements of some of the clinical outcomes such as vital signs and glucose levels. Finally, human biomonitoring can be efficiently done at a population level, providing accurate estimates of in-vivo absorbed pollutants and allowing for the evaluation of body responses, by biomarkers examination. We suggest that the adoption of these novel methods will change the research paradigm heavily relying on ecological methodology and support development of the new clinical practices preventing adverse environmental effects on human health.

FGA isoform as an indicator of targeted therapy for EGFR mutated lung adenocarcinoma

Epidermal growth factor receptor (EGFR) gene is frequently mutated in non-small cell lung cancer (NSCLC), which can be targeted by EGFR tyrosine kinase inhibitors (TKIs). It is hard, however, to monitor the performance of EGFR-TKI therapy dynamically. Therefore, therapeutic indicators are urgently needed. Novel antibody microarray, containing 41,472 antibodies, was used for comprehensive analyzing of serum samples from 9 normal subjects and 9 EGFR mutated lung adenocarcinoma patients at three EGFR-TKI treatment time points, including before treatment (Baseline), partial response (PR) during treatment, and disease progression (PD) after resistance. Through microarray data analysis, five candidate antibodies were screened out for confirmation in serum samples and the verified one was utilized for candidate protein identification through immunoprecipitation-mass spectrometry strategy. A novel protein, isoform 2 of fibrinogen alpha chain (FGA2), was revealed and verified in the discovery sample set. Its performance as therapy indicator was further evaluated in another pre-validation sample set (n = 60). Our data confirmed that serum FGA2 level was correlated with EGFR-TKI response (p < 0.05). The expression and secretion of FGA2 in hepatocytes were inhibited by EGFR-TKI, partially explaining the downregulation of FGA2 in serum. Our results demonstrate that FGA2 is an indicator of targeted therapy for EGFR mutated lung adenocarcinoma. KEY MESSAGES: Antibody microarray was coupled with mass spectrometry for proteomics research. FGA2 was discovered as an indicator of EGFR-TKI targeted therapy. FGA2's expression/secretion in hepatocytes was dramatically inhibited by EGFR-TKI.

Periodontal, metabolic, and cardiovascular disease: Exploring the role of inflammation and mental health

Previous evidence connects periodontal disease, a modifiable condition affecting a majority of Americans, with metabolic and cardiovascular morbidity and mortality. This review focuses on the likely mediation of these associations by immune activation and their potential interactions with mental illness. Future longitudinal, and ideally interventional studies, should focus on reciprocal interactions and cascading effects, as well as points for effective preventative and therapeutic interventions across diagnostic domains to reduce morbidity, mortality and improve quality of life.

State-of-the-Art Review: Usefulness of Laboratory Techniques for Evaluating Antithrombotic Efficacy of New Therapeutic Strategies

New drugs and new therapeutic strategies are being introduced for the prevention and the management of cardiovascular and thromboembolic disorders. Extensive clinical studies and large-scale epidemiological investigations are conducted to demonstrate the efficacy of these therapeutic approaches. Laboratory assays are invaluable tools for this exploration. We discuss how the new understanding concerning the regulation of the coagulolytic equilibrium offers novel investigation tools. Parameters reflecting the activities of new drugs targeted to their impact site and presenting few side effects are available. In addition to global clotting methods and chromogenic substrate-based assays, introduction of immunoassays has allowed measurement of most of the molecular markers of hemostatic activation. We recommend use of a panel of markers exploring the endothelial damage, the blood cell involvement, the early coagulant pathways' activation (XIIa and VIIa), the thrombin-formation pathways, the fibrin formation, and the evaluation of the global fibrinolytic capacity. When related to the clinical end points, all these laboratory assays offer useful and reliable monitoring of new drugs. They contribute to the establishment of new therapeutic strategies. Key Words: Hemostasis—Activation—Antithrombotic—Therapy— Laboratory monitoring.

State-of-the-Art Review: Molecular Markers in Thrombosis and Hemostasis

Molecular markers for exploring the different stages of hemostasis activation are now available. These markers allow investigation of endothelial functions, blood cell activation, stimulation of coagulation pathways, involvement of the fibrinolytic system, and profiling of the coagulolytic-equilibrium that regulates hemostasis. Additionally, these markers find useful applications for monitoring therapies, following-up clinical states associated with high thrombotic risk, and validating new drugs and analyzing their mode of action. Furthermore, these markers may allow for recognition of the evolution of early disease in the clinically silent phase. Large scale epidemiological and longitudinal studies are required for establishing this latter approach. Up to now, only D. Dimer is used in routine clinical application for exclusion diagnosis of deep-veinous-thrombosis and pulmonary embolism. Other markers must prove their sensitivity for the early asymptomatic period and demonstrate their applicability throughout disease evolution. According to pathology and application, different markers may provide complementary information. Some markers, e.g., D. Dimer, soluble thrombomodulin, and modified AT-III (ATM), are used on standard citrated plasma samples. Modem and flexible technologies are now available for point-of-care testing (when required), quick and sensitive measurements in emergency conditions, and full automation when necessary. Lastly, factors that trigger hemostatic activation can now be evaluated and provide information on etiology. In this latter respect, autoimmunity may be important in thrombotic disease induction. Key Words: Hemostatic activation—Molecular markers— Thrombosis—Predictivity—Monitoring antithrombotic therapies.

Vaccenic acid and trans fatty acid isomers from partially hydrogenated oil both adversely affect LDL cholesterol: a double-blind, randomized controlled trial

BACKGROUND

Adverse effects of industrially produced trans fatty acids (iTFAs) on the risk of coronary artery disease are well documented in the scientific literature; however, effects of naturally occurring trans fatty acids (TFAs) from ruminant animals (rTFA), such as vaccenic acid (VA) and cis-9,trans-11 conjugated linoleic acid (c9,t11-CLA), are less clear. Although animal and cell studies suggest that VA and c9,t11-CLA may be hypocholesterolemic and antiatherogenic, epidemiologic data comparing rTFAs and iTFAs are inconsistent, and human intervention studies have been limited, underpowered, and not well controlled.

OBJECTIVE

We determined the effects of VA, c9,t11-CLA, and iTFA, in the context of highly controlled diets (24 d each), on lipoprotein risk factors compared with a control diet.

RESULTS

We conducted a double-blind, randomized, crossover feeding trial in 106 healthy adults [mean ± SD age: 47 ± 10.8 y; body mass index (in kg/m(2)): 28.5 ± 4.0; low-density lipoprotein (LDL) cholesterol: 3.24 ± 0.63 mmol/L]. Diets were designed to have stearic acid replaced with the following TFA isomers (percentage of energy): 0.1% mixed isomers of TFA (control), ∼3% VA, ∼3% iTFA, or 1% c9,t11-CLA. Total dietary fat (34% of energy) and other macronutrients were matched. Total cholesterol (TC), LDL cholesterol, triacylglycerol, lipoprotein(a), and apolipoprotein B were higher after VA than after iTFA; high-density lipoprotein (HDL) cholesterol and apolipoprotein AI also were higher after VA. Compared with control, VA and iTFA both increased TC, LDL cholesterol, ratio of TC to HDL cholesterol, and apolipoprotein B (2-6% change; P < 0.05); VA also increased HDL cholesterol, apolipoprotein AI, apolipoprotein B, and lipoprotein(a) (2-6% change; P < 0.05), whereas iTFA did not. c9,t11-CLA lowered triacylglycerol (P ≤ 0.01) and had no effect on other lipoprotein risk factors.

CONCLUSIONS

With respect to risk of cardiovascular disease, these results are consistent with current nutrition labeling guidelines, with the requirement of VA, but not c9,t11-CLA, to be listed under TFA on the Nutrition Facts Panel. This trial was registered at clinicaltrials.gov as NCT00942656.

Effect of the -148C/T, 448G/A, and -854G/A Polymorphisms of the β-Fibrinogen Gene on the Risk of Ischemic Stroke in Chinese Population

BACKGROUND

Several investigations have been performed to examine the influence of the β-fibrinogen (FGβ) gene polymorphisms on the risk of ischemic stroke, but the results of these studies are controversial. Our study aimed at investigating whether the FGβ gene (-148 C/T, 448 G/A, and -854 G/A) polymorphisms were associated with susceptibility to ischemic stroke by conducting meta-analysis.

METHODS

Relevant studies were identified from 4 Chinese databases, PUBMED and EMBASE before May 30, 2014. The strength of association was evaluated by the odds ratio with 95% confidence interval. Inconsistency index and the Cochran's Q statistic were used to check heterogeneity. Publication bias was tested using funnel plots and Egger's regression test.

RESULTS

Thirty-two independent studies with 4311 cases and 4124 controls were included. Significant association between -148 C/T polymorphism and the risk of ischemic stroke was found in overall analysis and middle-age, but not in young adults and elderly people. Similarly, association was also observed for -854 G/A polymorphism, especially in cerebral arterial main trunk infarction (MCI) and cerebral penetrating arterial infarction (PCI). However, no significance was found between 448 G/A polymorphism and ischemic stroke in Chinese people; likewise, no evidence of a significant association was observed when stratified according to the subtype of ischemic stroke (MCI and PCI).

CONCLUSIONS

These results suggest that -148 C/T and -854 G/A polymorphisms probably contribute to susceptibility of ischemic stroke.

Severity of obstructive sleep apnea is associated with elevated plasma fibrinogen in otherwise healthy patients

PURPOSE

Obstructive sleep apnea (OSA) has been implicated in both cardiovascular and cerebrovascular diseases. Systemic inflammation and coagulation may be related to cardiovascular pathophysiology in patients with OSA. Fibrinogen is a major coagulation protein associated with inflammation, and long-term elevated plasma fibrinogen is associated with an increased risk of major cardiovascular diseases. We assessed whether severity of OSA is associated with levels of fibrinogen in newly diagnosed, untreated, and otherwise healthy OSA patients.

METHODS

We studied 36 men with OSA and 18 male control subjects (apnea-hypopnea index [AHI]<5 events/h). OSA patients were divided into mild (AHI≥5<15 events/h) and severe (AHI≥15 events/h) OSA groups. Morning fibrinogen levels in OSA patients were compared to those in control subjects of similar age, body mass index, blood pressure, smoking habits, and alcohol consumption.

RESULTS

Fibrinogen levels were significantly elevated in patients with severe OSA compared to both control (P=0.003) and mild OSA (P=0.02) subjects after adjustment for covariates. However, there were no significant differences in fibrinogen levels between mild OSA and control subjects. Fibrinogen levels were directly related to AHI and arousal index and inversely related to mean and lowest oxygen saturation during sleep.

CONCLUSIONS

Severity of OSA was associated with increased fibrinogen level independent of other factors, suggesting that apneic events and oxygen desaturation during sleep are mechanisms for increased fibrinogen levels in patients with OSA.

Treating thrombus in the coronary arteries

Primary percutaneous coronary intervention (PCI) has greatly improved outcomes in patients with ST-elevation myocardial infarction (STEMI) and has, therefore, become the preferred reperfusion strategy for this patient group. The goal of primary PCI is to achieve a thrombolysis in myocardial infarction (TIMI) 3 flow and also to restore adequate perfusion at the myocardial level. Distal thrombus embolization during primary PCI occurs frequently and is also associated with compromised long-term outcomes. In this article, we provide an overview of the treatment of thrombus and the role of thrombectomy in PCI for STEMI.

Obesity-related increased γ' fibrinogen concentration in children and its reduction by a physical activity-based lifestyle intervention: a randomized controlled study

OBJECTIVE

To determine if elevated plasma γ'-fibrinogen, typically involved in the formation of fibrinolysis-resistant clots, confers an increased risk for cardiovascular disease (CVD) and thrombosis in children as it does in adults. Although obesity-related hyperfibrinogenemia is frequently reported in children, the role of γ' fibrinogen and its response to physical activity-based lifestyle are less clear in this population.

STUDY DESIGN

In a randomized controlled 3-month physical activity-based lifestyle intervention, γ' fibrinogen concentration was measured in 21 children (aged 14-18 years; Tanner stage > IV), including 15 in the obese group and 6 in the normal weight group, with body mass index percentiles for age and sex of >95 and <85, respectively.

RESULTS

The relationships between γ' fibrinogen and other risk factors for CVD, such as markers of insulin resistance and subclinical inflammation, along with body composition (as measured by dual-energy X-ray absortiometry), were assessed before and after the intervention. γ' fibrinogen concentration was higher in the obese group compared with the normal weight group (P < .05) and was correlated with other risk factors for CVD (adjusted R(2) = 0.9; P < .05), and insulin emerged as the major predictor of γ' fibrinogen. The intervention reduced γ'-fibrinogen concentration (P < .05).

CONCLUSION

Our data reveal: (1) elevated γ' fibrinogen concentrations in obese insulin-resistant children compared with normal lean controls; (2) a relationship between γ' fibrinogen and other CVD risk factors; and (3) physical activity-induced reduction in γ' fibrinogen in obese children.

Determining the Relationship Between Homocysteinemia and Biomarkers of Inflammation, Oxidative Stress and Functional Kidney Status in Patients with Diabetic Nephropathy

Background: One of the leading causes of terminal renal failure is diabetic nephropathy. The aim of this study was to determine the relationship between homocysteine levels and the biomarkers of renal function, inflammation and oxidative stress, as well as the incidence of macrovascular complications in patients with diabetic nephropathy.

Methods: Sixty-four patients with diabetic nephropathy were included in this study. They were divided according to their homocysteine levels into two groups: hyperhomocysteinemic (HHcy, n=47) and normohomocysteinemic patients (NHCy, n=17). The re sults were compared to a control group (n=20) with normal renal function and without diabetes. Besides homocysteine, cystatine C, creatinine, urea, albuminuria, creatinine clearance, lipid status parameters, apolipoprotein A-I and B, lipo protein (a), CRP, fibrinogen, oxidative LDL were determined using appropriate methods. The incidence of macro vascular diabetic complications was also determined.

Results: The results indicate that the level of renal dysfunction is greater in HHcy than in NHcy patients (p<0.05). In HHcy patients levels of oxLDL were also higher compared to NHcy patients (119.3±140.4 vs. 71.4±50.8 ng/mL, disp< 0.05) as well as fibrinogen levels (4.3±1.3 vs. 3.7±0.8 g/L, p<0.05). The in cidence of macrovascular complications is more frequent in HHcy than in NHcy patients (55.3. vs. 35.3 %, p>0.05), and in patients with macroalbuminuria compared to patients with microalbuminuria (65% vs. 39%, p<0.05).

Conclusions: It can be concluded that HHcy is significantly present in patients with diabetic nephropathy, especially if there is greater reduction of renal function. Besides that, significantly higher concentrations of inflammatory (fibrinogen) and oxidative stress (oxLDL) markers were present in HHcy patients with diabetic nephropathy compared to NHcy patients.Therefore in diabetic nephropathy patients it is useful to regularly monitor the levels of homocysteine, as well as inflammatory and markers of oxidative stress.

Differential Expression of Platelet Activation Markers CD62P and CD63 Following Stimulation with PAF, Arachidonic Acid and Collagen

The effects of varying concentrations of platelet-activating factor (PAF), arachidonic acid (AA) and collagen on the expression of the platelet activation markers CD63 and CD62P were assessed in 10 normal subjects using flow cytometry. CD63 expression was significantly greater than CD62P expression, with PAF (80 nM) inducing mean maximum CD63 expression of 32.9 ± 6.4% and mean maximum CD62P expression of 5.5 ± 1.8%. AA (1 mM) induced maximum CD63 expression of 37.7 ± 7% and maximum CD62P expression of 9.3 ± 1%. Collagen (2-80 pg/ml) induced minimal expression but 800 pg/ml induced mean CD63 expression of 33.1 ± 4.1% and mean CD62P expression of 6.1 ± 0.8%. Greater CD63 and CD62P expression were induced by phorbol myristate acetate (1.6 pM, 70.9 ± 11% and 69.4 ± 9.9%, respectively) and thrombin (0.1 U/ml, 70.7 ± 9.3% and 73.5 ± 5.4%, respectively). With PAF and collagen only one platelet population was detected whereas with 1 mM AA two populations were observed. These results indicate that expression of platelet adhesion receptors depends on the nature and concentration of agonist and that subpopulations of platelets may exist. Importantly, PAF concentrations inducing moderate CD63 and CD62P expression did not induce platelet aggregation, suggesting that platelets can be activated independently of aggregation.

Fish Oil Supplementation Inhibits Platelet Aggregation and ATP Release Induced by Platelet-activating Factor and Other Agonists

The anti-inflammatory effects of fish oil may partly be due to the inhibition of platelet activation induced by platelet-activating factor (PAF) and other agonists. To investigate this hypothesis, the diets of 12 healthy volunteers were supplemented with 12 fish oil capsules or 12 olive oil capsules daily for 4 weeks in a double blind crossover study. Aggregation induced by PAF (18 and 12.5 nM) and collagen (20 μg/ml)tended to be reduced after fish oil but the effect was statistically significant only in subjects receiving fish oil in the 6rst 4 weeks of the study (P 0.05, n=6). The effect of fish oil supplementation on platelet ATP release was more marked with significant inhibition of ATP release induced by PAF (1200 and 36 nM, P 0.01, n = 12), collagen (20 μg/ml, P 0.005, n = 12) and ADP (15,10 and 5 μM, P 0.05, n = 12). Olive oil supplementation appeared to inhibit ATP release induced by collagen (45 and 30 μg/ml, P> 0.025, n = 12), while aggregation and ATP release induced by arachidonic acid and adrenaline were unaffected by the supplements. Plasma fibrinogen was significantly reduced after olive oil (P 0.01, n = 12) while prothrombin time was reduced after fish oil (P 0.001, n = 12) and olive oil (P 0.0025). Reduced platelet aggregation and more importantly, inhibition of platelet release induced by PAF and other agonists may contribute to the anti-inflammatory effects of fish oil supplementation in a number of disease states but olive oil may also independently affect platelet function and influence the effect offish oil.

Coagulability in obstructive sleep apnea

BACKGROUND

Obstructive sleep apnea (OSA) is a common disorder that affects both quality of life and cardiovascular health. The causal link between OSA and cardiovascular morbidity⁄mortality remains elusive. One possible explanation is that repeated episodes of nocturnal hypoxia lead to a hypercoagulable state that predisposes patients to thrombotic events. There is evidence supporting a wide array of hematological changes that affect hemostasis (eg, increased hematocrit, blood viscosity, platelet activation, clotting factors and decreased fibrinolytic activity).

OBJECTIVE

To provide a comprehensive review of the current evidence associating OSA with increased coagulability, and to highlight areas for future research.

METHODS

Keyword searches in Ovid Medline were used to identify relevant articles; all references in the articles were searched for relevant titles. The Web of Science was used to identify articles citing the relevant articles found using the Ovid Medline search. All original peer-reviewed articles, meta-analyses and systematic reviews regarding the pertinent topics between 1990 and present were selected for review.

RESULTS

Hematocrit, blood viscosity, certain clotting factors, tissue factor, platelet activity and whole blood coagulability are increased in patients with OSA, while fibrinolysis is impaired.

CONCLUSION

There is considerable evidence that OSA is associated with a procoagulant state. Several factors are involved in the procoagulant state associated with OSA. There is a need for adequately powered clinical studies involving well-matched control groups to address potential confounding variables, and to accurately delineate the individual factors involved in the procoagulant state associated with OSA and their response to treatment.

Interaction between fibrinogen and IL-6 genetic variants and associations with cardiovascular disease risk in the Cardiovascular Health Study

The inflammatory cytokine interleukin-6 (IL-6) is a main regulator of fibrinogen synthesis, though its interaction with fibrinogen genes (FGA, FGB, FGG) and subsequent impact on cardiovascular disease (CVD) risk is not well-studied. We investigated joint associations of fibrinogen and IL6 tagSNPs with fibrinogen concentrations, carotid intima-media thickness, and myocardial infarction or ischemic stroke in 3900 European-American Cardiovascular Health Study participants. To identify combinations of genetic main effects and interactions associated with outcomes, we used logic regression. We also evaluated whether the relationship between fibrinogen SNPs and fibrinogen level varied by IL-6 level using linear regression models with multiplicative interaction terms. Combinations of fibrinogen and IL6 SNPs were significantly associated with fibrinogen level (p < 0.005), but not with other outcomes. Fibrinogen levels were higher in individuals having FGB1437 (rs1800790) and lacking FGA6534 (rs6050) minor alleles; these SNPs interacted with IL6 rs1800796 to influence fibrinogen level. Marginally significant (p= 0.03) interactions between IL-6 level and FGA and FGG promoter SNPs associated with fibrinogen levels were detected. We identified potential gene-gene interactions influencing fibrinogen levels. Although IL-6 responsive binding sites are present in fibrinogen gene promoter regions, we did not find strong evidence of interaction between fibrinogen SNPs and IL6 SNPs or levels influencing CVD.

Acute phase proteins: C-reactive protein and fibrinogen in young women with polycystic ovary syndrome

Females with polycystic ovary syndrome (PCOS) are characterized by several metabolic abnormalities that favor the development of atherosclerosis. Atherosclerosis is possibly a chronic inflammatory process, and the markers of the inflammatory state, such as C-reactive protein (CRP) and fibrinogen may be useful to assess the global risk of developing cardiovascular diseases. These proteins might be helpful in finding females with subclinical atherosclerosis. The purpose of this study was to assess the serum CRP and fibrinogen concentrations in young females with PCOS and to clarify the possible correlations between their levels and selected anthropometric, metabolic and hormonal indices. Study assessed a group of 57 females with PCOS (mean age 28.2+/-6.4 years). That group was further divided into two subgroups: the first with body mass index (BMI)</=25 (21 females of mean age 27.4+/-7.0 years) and second with BMI>25 (36 females of mean age 28.6+/-6.0 years). In the control group there were 22 healthy females (mean age 31.6+/-8.5 years). That group was again divided into two subgroups: the first with BMI</=25 (10 females, mean age 30.2+/-8.4 years) and second with BMI>25 (12 females, mean age 31.7+/-8.7 years). Results demonstrated statistically significantly higher CRP concentration in females with PCOS compared to healthy individuals in both BMI subgroups. PCOS females showed also higher plasma insulin levels. There was, however, no statistically significant difference in fibrinogen concentrations. The hormonal profile of females with PCOS seems to influence the concentration of CRP and fibrinogen in different ways. This was evident in the positive correlation between plasma fibrinogen and androstenedione and in the lack of correlation between CRP and androgens and in the positive correlation between CRP and estradiol and the negative correlation between fibrinogen and estradiol. In conclusion, high CRP concentration in females with PCOS probably speaks for a higher risk for cardiovascular diseases.

Effects of testosterone on lipid peroxidation, lipid profiles and some coagulation parameters in rabbits

The purpose of this study was to investigate the effects of testosterone on some risk factors of atherosclerosis. Twenty-four male New Zealand white rabbits were randomly divided into three groups of eight. The first group was used as control. Second group was injected with 10 mg of testosterone propionate. Third group was castrated bilaterally. At the end of 6 weeks, lipid peroxidation (LPO), lipid profile, fibrinogen (FBN) level and coagulation parameters were evaluated. Testosterone administration decreased the level of high-density lipoprotein cholesterol (HDL-C), while castration increased this level (P < 0.05). Triglyceride (TG) and total cholesterol (TC) levels in the castration group were significantly higher (P < 0.05) than those in the testosterone group. The ratio of HDL-C:low-density lipoprotein cholesterol (LDL-C) decreased, while TC:HDL-C ratio increased (P < 0.05) in the testosterone group. No significant differences were found in the LDL-C and FBN levels among groups. However, there was a tendency for higher FBN level in the testosterone group. Testosterone administration resulted in an increase in the level of LPO (P < 0.05). Clotting time and prothrombin time prolonged in the castration group compared with testosterone group (P < 0.05). As a result, testosterone has exacerbating effect on atherosclerosis risk factors including lipid profile, LPO, FBN and coagulation system.

Effects of particulate matter on the pulmonary and vascular system: time course in spontaneously hypertensive rats

Background

This study was performed within the scope of two multi-center European Commission-funded projects (HEPMEAP and PAMCHAR) concerning source-composition-toxicity relationship for particulate matter (PM) sampled in Europe. The present study aimed to optimize the design for PM in vivo toxicity screening studies in terms of dose and time between a single exposure and the determination of the biological responses in a rat model mimicking human disease resulting in susceptibility to ambient PM. Dust in thoracic PM size-range (aerodynamic diameter <10 μm) was sampled nearby a road tunnel (RTD) using a high volume cascade impactor. Spontaneously hypertensive rats were exposed to urban dust collected in Ottawa, Canada (EHC-93 10 mg/kg of body weight; reference PM) or different RTD doses (0.3, 1, 3, 10 mg/kg of body weight) by intratracheal instillation. Necropsy was performed at 4, 24, or 48 hr after exposure.

Results

The neutrophil numbers in bronchoalveolar lavage fluid increased tremendously after exposure to the highest RTD doses or EHC-93. Furthermore, PM exposure slightly affected blood coagulation since there was a small but significant increase in the plasma fibrinogen levels (factor 1.2). Pulmonary inflammation and oxidative stress as well as changes in blood coagulation factors and circulating blood cell populations were observed within the range of 3 to 10 mg PM/kg of body weight without significant pulmonary injury.

Conclusion

The optimal dose for determining the toxicity ranking of ambient derived PM samples in spontaneously hypertensive rats is suggested to be between 3 and 10 mg PM/kg of body weight under the conditions used in the present study. At a lower dose only some inflammatory effects were detected, which will probably be too few to be able to discriminate between PM samples while a completely different response pattern was observed with the highest dose. In addition to the dose, a 24-hr interval from exposure to sacrifice seemed appropriate to assess the relative toxic potency of PM since the majority of the health effects were observed one day after PM exposure compared to the other times examined. The aforementioned considerations provide a good basis for conducting PM toxicity screening studies in spontaneously hypertensive rats.

Conditional risk factors for atherosclerosis

Although most patients who experience a coronary heart disease (CHD) event have one or more of the conventional risk factors for atherosclerosis, so do many people who have not yet experienced such an event. Therefore, predictive models based on conventional risk factors have a lower than desired accuracy, providing a stimulus to search for new tools to refine CHD risk prediction. In particular, there is intense interest in evaluating circulating biomarkers related to the atherosclerotic process that might add to our ability to better predict CHD risk. One such group of biomarkers was termed conditional risk factors in an American Heart Association/American College of Cardiology statement in 1999. The conditional risk factors include homocysteine, fibrinogen, lipoprotein(a), low-density lipoprotein particle size, and C-reactive protein. This review updates the conditional risk factors. The main focus is on the potential utility of these risk factors, which are currently available to clinicians, in the prediction of CHD risk in asymptomatic persons. The putative mechanisms of risk, available assays, evidence for association with CHD, and the clinical implications thereof are discussed for each of the risk factors.

Impact of kidney transplantation on the progression of cardiovascular disease

Kidney transplantation, of all the treatment modalities for end-stage renal disease, affords the greatest potential for prolonged survival and improved quality of life. Great strides in immunosuppressant therapy have improved graft survival and forced clinicians to consider other health-care needs of kidney transplant recipients. Chief among these needs is the prevention and treatment of cardiovascular disease. Cardiovascular disease is the most common cause of death among patients with a working renal allograft. Because therapies for primary and secondary prevention are successful in the general population, transplant clinicians are increasingly focused on preventing or limiting the progression of cardiovascular disease. Initiation of aggressive management of conventional atherosclerotic risk factors and uremia-related risk factors, ideally during the early stages of chronic kidney disease (CKD) or after kidney transplantation, and efforts to delay the progression of kidney disease will hopefully reduce the cardiovascular burden in transplant recipients.

Association of markers of systemic inflammation, C reactive protein, serum amyloid A, and fibrinogen, with socioeconomic status

STUDY OBJECTIVE

Systemic inflammation may play an important part in the development of cardiovascular disease. It has also been shown that socioeconomic status predicts cardiovascular events independently of established risk factors. The aim of this study was to analyse the association of three sensitive markers of systemic inflammation: C reactive protein (CRP), serum amyloid A protein (SAA), and fibrinogen, with socioeconomic status.

DESIGN

Cross sectional study.

SETTING

Eastern and southern Finland.

PARTICIPANTS

1503 men aged 45 to 74 years who participated in a cardiovascular risk factor survey in 1997. Based on the levels of education and family income, the men were classified to three socioeconomic groups.

MAIN RESULTS

Mean concentrations of CRP (p for the trend <0.001), SAA (p for the trend 0.018), and fibrinogen (p for the trend <0.001) decreased substantially with increasing socioeconomic status. The trends in CRP and fibrinogen remained statistically significant after adjustment for smoking, waist to hip ratio, and prevalent longstanding diseases, and a non-significant trend was found for SAA (p for the trend 0.118). The inverse association between inflammation markers and socioeconomic status was particularly strong among the men below 60 years of age.

CONCLUSIONS

Systemic inflammation is a potential mediator, especially among young and middle aged men, for the association between socioeconomic status and cardiovascular disease.

Role of inflammation in cardiovascular disease: how to use C-reactive protein in clinical practice

Acute coronary syndromes, stroke, and sudden death are common complications of a disrupted atherosclerotic plaque. Unstable plaque is a result of multiple factors but is commonly characterized by an infiltrate of inflammatory cells. Medical research strongly supports a role for inflammation in the pathogenesis, progression, and disruption of atherosclerotic plaque. Medical science also has improved our understanding of the complex interactions between our environment and our immune, coagulation, and cardiovascular systems. Clinical studies have demonstrated systemic markers of inflammation to be strong predictors of clinical events, and specific treatments of atherosclerosis and its risk factors have been associated with reductions in inflammatory markers. The authors review the current understanding of the role of inflammation in the pathogenesis of atherosclerosis, the common inflammatory markers, and potential anti-inflammatory therapy. Among several potential circulating markers of vascular inflammation, high sensitivity C-reactive protein is best validated and standardized as a marker for cardiovascular risk assessment. Nevertheless, there remain many uncertainties in utilizing C-reactive protein in clinical practice. Here, the authors describe the central role of C-reactive protein in atherosclerosis, review the studies demonstrating predictive value of C-reactive protein, describe the factors requiring consideration when utilizing C-reactive protein, discuss clinical scenarios in which measurement of C-reactive protein may be helpful, and suggest ways to interpret and treat elevated C-reactive protein levels. Finally, the authors summarize future expectations for assessing and modulating the vascular inflammation to inhibit initiation and progression of the atherosclerotic process.

The association of sensitive systemic inflammation markers with bronchial asthma

BACKGROUND

Airway inflammation is a characteristic feature of bronchial asthma. Previous studies have shown an increased local inflammatory activity in the airway mucosa of asthma patients.

OBJECTIVES

To analyze the association of asthma with three sensitive markers of systemic inflammation, C-reactive protein, serum amyloid-A (SAA), and plasma fibrinogen.

METHODS

A cross-sectional, population-based study including 1,513 Finnish men aged 45 to 74 years, who participated in a chronic disease risk factor survey in 1997. Of the participating men, 97 were classified as asthma patients. The odds ratios of asthma were analyzed by quartile of each inflammation marker.

RESULTS

In logistic regression models the age-adjusted odds ratios (second, third, and fourth quartile as compared with the first quartile) of asthma increased gradually with increasing quartile of C-reactive protein (1.28, 1.19, 1.96, P for trend = 0.039), SAA (1.20, 3.00, 3.49, P for trend < 0.001), and fibrinogen (1.22, 1.79, 3.16, P for trend < 0.001). The associations were independent of smoking. Further adjustment for waist-to-hip ratio, a marker of central obesity, and symptoms of chronic bronchitis weakened the observed association, but the increasing trend in the association of SAA and fibrinogen with asthma remained highly significant.

CONCLUSIONS

Sensitive markers of systemic inflammation, particularly SAA and fibrinogen, were positively and significantly associated with asthma prevalence. These findings support the hypothesis that not only local, but also systemic, inflammation exist in bronchial asthma.

Systemic vascular disease in male B6C3F1 mice exposed to particulate matter by inhalation: studies conducted by the National Toxicology Program

Epidemiological studies suggest an association between ambient particulate matter and cardiopulmonary diseases in humans. The mechanisms underlying these health effects are poorly understood. To better understand the potential relationship between particulate-matter-induced inflammation and vascular disease, a 2-phase retrospective study was conducted. Phase one included the review of heart, lung, and kidney tissues from high-dose and control male B6C3F1 mice exposed by inhalation to 9 particulate compounds for a 2-year period. The results showed that high-dose males developed significantly increased incidences of coronary and renal arteritis over controls in 2 of the 9 studies (indium phosphide and cobalt sulfate heptahydrate), while marginal increases in arteritis incidence was detected in 2 additional studies (vanadium pentoxide and gallium arsenide). In contrast, arteritis of the muscular arteries of the lung was not observed. Morphological features of arteritis in these studies included an influx of mixed inflammatory cells including neutrophils, lymphocytes, and macrophages. Partial and complete effacement of the normal vascular wall architecture, often with extension of the inflammatory process into the periarterial connective tissue, was observed. Phase 2 evaluated the heart, lung, kidney, and mesentery of male and female B6C3F1 mice from the 90-day studies of the 4 compounds demonstrating arteritis after a 2-year period. The results showed arteritis did not develop in the 90-day studies, suggesting that long-term chronic exposure to lower-dose metallic particulate matter may be necessary to induce or exacerbate arteritis.

Association of fibrinogen and lipoprotein(a) as a coronary heart disease risk factor in men (The Quebec Cardiovascular Study)

Fibrinogen has been prospectively found to correlate with coronary heart disease (CHD) but a similar association has not been well established for lipoprotein (a) (Lp(a)). Plasma lipids, Lp(a), and fibrinogen levels were measured in 2,125 men (aged 47 to 76 years) who were free of clinical CHD. During a 5-year follow-up period, 116 first CHD events were documented. Men with CHD were older, smoked more, had a higher prevalence of diabetes, and higher levels of systolic blood pressure, cholesterol, low-density lipoprotein cholesterol, Lp(a), and fibrinogen, and lower plasma high-density lipoprotein cholesterol levels. Only fibrinogen levels in the upper tertile of the distribution compared with the lower tertiles were associated with a significant risk of CHD (adjusted risk ratio 2.5; 95% confidence interval [CI] 1.4 to 4.2; p = 0.0010). Such an association was not observed with Lp(a). To assess a possible relation between fibrinogen and Lp(a) to the risk of CHD events, men were assigned to 1 of 4 groups according to fibrinogen median levels and a Lp(a) cut-off level of 300 mg/L: group 1: fibrinogen < 4.05 g/L and Lp(a) < 300 mg/L; group 2: fibrinogen < 4.05 g/L and Lp(a) > or =300 mg/L; group 3: fibrinogen > or =4.05 g/L and Lp(a) < 300 mg/L; and group 4: fibrinogen > or =4.05 g/L and Lp(a) > or =300 mg/L. Using group 1 as a reference, a significant risk ratio was only documented in group 4 (2.5; 95% CI 1.2 to 5.1; p = 0.0132). In this population, high fibrinogen levels associated with high Lp(a) levels significantly increased the risk of CHD.

Associations between homocysteine and coagulation factors--a cross-sectional study in two populations of central Europe

Plasma homocysteine has been associated with vascular disease and mortality. Experimental studies and studies on patients with vascular disease have indicated a thrombogenic potential of raised homocysteine levels. Studies on community samples are rare. We investigated the associations between homocysteine levels and selected coagulation factors in population-based random samples of 187 men from Pardubice (Czech Republic) and 147 men from Augsburg (Germany), aged 45 to 64 years. Czech men had higher mean levels of plasma homocysteine (10.3 vs. 8.9 micromol/l, P<.001) and of fibrinogen, von Willebrand factor (vWF), prothrombin fragment 1+2 (F 1+2) and D-Dimer (each P<.05). Plasma homocysteine was positively correlated with fibrinogen (r=.34) and vWF (r=.23, each P<.001) only in Czechs, and with D-Dimer in both Czechs and Germans (r=.26 and.21, respectively). Formal testing for interaction regarding the intercountry differences in the relationship with homocysteine revealed significance only for fibrinogen (P<.01). In multivariate analyses, the association of homocysteine with D-Dimer remained statistically significant after adjustment for indicators of chronic inflammation and fibrinogen. No significant correlation was found with Factor VII (F VII) activity or F 1+2. Homocysteine levels were also unrelated to traditional risk factors. In conclusion, in these cross-sectional studies we found moderate to strong associations between homocysteine and components of the endogenous hemostatic and fibrinolytic systems. The associations were slightly different between Czech and German men. These findings may help to better understand the role of homocysteine in atherothrombotic diseases.

Racial and genetic determinants of plasma factor XIII activity

Factor XIII (F XIII), a plasma transglutaminase, is essential for normal hemostasis and fibrinolysis. Plasma F XIII consists of two catalytic A (F XIIIA) and two non-catalytic B (F XIIIB) subunits. Activated F XIII is involved in the formation of fibrin gel by covalently crosslinking fibrin monomers. As the characteristics of the fibrin gel structure have been shown to be associated with the risk of coronary heart disease (CHD), F XIII activity may play a seminal role in its etiology. In this investigation, we determined plasma F XIII activity in two racial groups, including Asian Indians (n = 258) and Chinese (n = 385). Adjusted plasma F XIII activity was significantly higher in Indian men (142 vs. 110%; P<0.0001) and women (158 vs. 111%; P<0.0001) than their Chinese counterparts. As compared to Indians where the distribution of F XIII activity was almost normal, in Chinese it was skewed towards low activity. In both racial groups, bivariate and multivariate analyses showed strong correlation of F XIII activity with plasma fibrinogen and plasminogen levels. Race explained about 25% of the variation in F XIII activity even after the adjustment of significant correlates. We also determined the contribution of common genetic polymorphisms in the F XIIIA and F XIIIB genes in affecting plasma F XIII activity. Both loci showed significant and independent effects on plasma F XIII activity in Indians (F XIIIA, P< 0.01; F XIIIB, P<0.05) and Chinese (F XIIIA, P<0.0001; F XIIIB, P<0.13) in a gene dosage fashion. This study shows that both racial and genetic components play a significant role in determining plasma F XIII activity, and consequently it may affect the quantitative risk of CHD.

A residential study comparing the effects of diets rich in stearic acid, oleic acid, and linoleic acid on fasting blood lipids, hemostatic variables and platelets in young healthy men

Dietary fat is known to influence the variables of blood coagulation and fibrinolysis associated with vascular disease. However, the role of fat content and/or fat composition of the diet in this regard is still not well understood. In the present study, we investigated the effects of three isoenergic diets of differing fat composition in nine healthy young men in a strictly controlled residential study. Subjects consumed the three experimental diets for periods of 2 weeks each, separated by a washout period of at least 5 weeks in a randomized crossover design. The diets provided 38% of total energy intake as fat, 45% as carbohydrate, and 17% as protein, and differed only with respect to the fatty acid composition (stearic acid-rich diet: 34.1% stearic acid, 36.6% oleic acid; oleic acid-rich diet: 65.8% oleic acid; linoleic acid-rich diet: 36.5% linoleic acid, 38% oleic acid). Blood samples were collected at the beginning and at the end of each dietary period from fasted subjects for determination of factor VII coagulant activity (FVIIc), activated factor VII (FVIIa), factor VII antigen (FVIIag), tissue plasminogen activator (tPA) activity, plasminogen activator inhibitor type 1 (PAI-1) activity, fibrinogen, prothrombin fragment 1+2 (F(1+2)), and plasma lipids. There were no significant differences between diets in fasting plasma concentrations of FVIIc, FVIIa, FVIIag, fibrinogen, F(1+2), PAI-1 activity, and tPA activity. Plasma concentrations of lipids (high density lipoproteins, low density lipoproteins, triacylglycerols, and total cholesterol) were also unaffected. Although there were no changes in platelet aggregation response and membrane fluidity observed in any of the diets, increased anti-aggregatory prostaglandin E(1) binding to platelet membranes was observed only in the case of linoleic acid-rich diet. In conclusion, diets with very different fatty acid compositions, at 38% of energy as fat intake, did not significantly influence blood coagulation, fibrinolysis, or blood lipids in the fasting state in young healthy men.

Novel risk factors for atherosclerosis

In the past several years, evidence has accumulated that factors other than conventional risk factors may contribute to the development of atherosclerosis. Conventional risk factors predict less than one half of future cardiovascular events. Furthermore, conventional risk factors may not have the same causal effect in different ethnic groups in whom novel risk factors may have a role. These newer risk factors for atherosclerosis include homocysteine, fibrinogen, impaired fibrinolysis, increased platelet reactivity, hypercoagulability, lipoprotein(a), small dense low-density lipoprotein cholesterol, and inflammatory-infectious markers. Identification of other markers associated with an increased risk of atherosclerotic vascular disease may allow better insight into the pathobiology of atherosclerosis and facilitate the development of preventive and therapeutic measures. In this review, we discuss the evidence associating these factors in the pathogenesis of atherosclerosis, the mechanism of risk, and the clinical implications of this knowledge.

The relationship of oxidized lipids to coronary artery stenosis

A total of 1200 patients with angina were cardiac catheterized establishing that 63% had 70-100% stenosis, 12% had 10-69% stenosis of one or more of their coronary arteries and 25% had microvascular angina listed as 0% stenosis. Prior to catheterization 10 ml of blood was drawn and the plasma subjected to analysis for the concentration of cholesterol, lipid peroxides (LPX), total antioxidant capacity (TAOC), fibrinogen (FB), ceruloplasmin (CP) and activation of polymorphonuclear leukocytes (PMNLs). Comparisons were made to non-smoking controls without angina. Significant differences in LPX were found between the patients with 0 and 10-69% stenosis (P<0.001), with 10-69 and 70-100% stenosis (P<0.001), and with 0 and 70-100% stenosis (P<0.001). Under 70 years of age there was a significant difference in LPX between patients with all levels of stenosis and age and sex matched controls (P<0.001). Differences in the mean plasma cholesterol concentration for different levels in the degree of stenosis were not significant, indicating that LPX provided consistent data on the severity of stenosis while the plasma cholesterol concentration did not. Compared with controls an increase in activation of PMNLs (P<0.01), an increase in concentration of both FB and CP (P<0.01) and a decrease in total antioxidant capacity were noted in the plasma of catheterized patients. In summary the concentration of oxidation products rather than the concentration of cholesterol in the plasma identified stenosis in cardiac catheterized patients.

Hyperfibrinogenemia is associated with specific histocytological composition and complications of atherosclerotic carotid plaques in patients affected by transient ischemic attacks

BACKGROUND

Epidemiological studies have demonstrated that hyperfibrinogenemia is an independent risk factor for cerebrovascular atherosclerosis. However, the underlying mechanisms are poorly understood. We studied whether hyperfibrinogenemia could modify the histological composition of atherosclerotic plaque and precipitate carotid thrombosis resulting from rupture of the plaque.

METHODS AND RESULTS

We studied the histological composition of 71 carotid atherosclerotic plaques from patients who had undergone surgical endarterectomy after a first episode of transient ischemic attack. Patients were divided into 3 groups corresponding to the tertiles of plasma fibrinogen values. Hypercholesterolemia, hypertriglyceridemia, hypertension, diabetes, and smoking habit were also assessed. At the histological analysis, plaques of patients in the highest tertile of fibrinogen (>407 mg/dL) were characterized by a high incidence of thrombosis (66.7% of cases) compared with plaques of subjects in the lower (21.7%) (P=0.002) and middle (29. 2%) (P=0.009) tertiles. Plaque rupture was significantly associated with high fibrinogen levels (54.2%, P=0.003). Multivariate logistic regression indicated that hyperfibrinogenemia was an independent risk factor for a decrease in cap thickness (P=0.0005), macrophage foam cell infiltration of the cap (P=0.003), and thrombosis (P=0. 003). When the presence of other risk factors was accounted for, hyperfibrinogenemia remained an independent predictor of carotid thrombosis with an odds ratio of 5.83, compared with other risk factors.

CONCLUSIONS

The results of the present study add to the evidence that hyperfibrinogenemia, independently of other risk factors, is associated with a specific histological composition of carotid atherosclerotic plaques that predisposes them to rupture and thrombosis.

Physical activity in the prevention and treatment of a thrombogenic profile in the obese: current evidence and research issues

PURPOSE

To evaluate the impact of regular physical activity on thrombogenic profile in obese individuals.

DESIGN

Medline-based literature search with emphasis on controlled randomized clinical trials. The focus was on the impact of physical activity on platelet aggregation, fibrinogen, and plasminogen activator inhibitor-1(PAI-1) in overweight and obese subjects.

RESULTS

Physical activity increases acutely 1) platelet number and activity, 2) activation of coagulation leading to a thrombin generation, and 3) simultaneous activation of fibrinolysis. On the other hand, hemostatic changes resulting from regular exercise training are limited to few data on platelets and blood coagulation and to some indications of increased fibrinolysis. Obesity is a risk factor for atherosclerotic cardiovascular diseases, and it is associated with hypertriglyceridemia, hyperinsulinemia, and non-insulin-dependent diabetes (NIDDM). These states interfere with a balance between blood coagulation and fibrinolysis leading to an increased thrombogenesis. Regular physical activity reduces platelet aggregability, while the effects on plasma fibrinogen and fibrinolytic activity remain unclear.

CONCLUSIONS

Although obesity associates with several unfavorable derangements in the hemostatic system, data on the interactions of regular physical activity with blood coagulation in overweight or obese subjects are scarce. Therefore, controlled randomized clinical trials with adequate statistical power are needed for the evaluation of physical activity in the prevention and treatment of obesity-related atherothrombotic disorders.

A prospective study of fibrinogen and risk of myocardial infarction in the Physicians' Health Study

OBJECTIVES

We examined the association of baseline plasma fibrinogen with future risk of myocardial infarction (MI) in the Physicians' Health Study.

BACKGROUND

Elevated plasma fibrinogen increases and low dose aspirin decreases risk of MI. However, prospective data are limited about their interrelationships.

METHODS

Blood samples were prospectively collected at baseline from 14,916 men in the Physicians' Health Study, aged 40 to 84 years, who were randomly assigned to take aspirin (325 mg every other day) or placebo for 5 years. We measured baseline plasma fibrinogen among 199 incident cases of MI and 199 age- and smoking-matched control subjects free of cardiovascular disease at the time of the case's diagnosis.

RESULTS

Cases had significantly higher baseline fibrinogen levels (geometric mean: 262 mg/dl) than did control subjects (245 mg/dl, p = 0.02). Those with high fibrinogen levels (> or =343 mg/dl, the 90th percentile distribution of the control subjects) had a twofold increase in MI risk (age- and smoking-adjusted relative risk = 2.09, 95% confidence interval = 1.15 to 3.78) compared with those with fibrinogen below 343 mg/dl. Adjustment for lipids and other coronary risk factors as well as randomized aspirin assignment did not materially change the result. Furthermore, we observed no interaction between fibrinogen level and aspirin treatment.

CONCLUSIONS

Among these apparently healthy U.S. male physicians, fibrinogen is associated with increased risk of future MI independent of other coronary risk factors, atherogenic factors such as lipids and antithrombotics such as aspirin.

The relationship between fibrinogen and other coronary heart disease risk factors in a Chinese population

Few studies have examined fibrinogen in Chinese populations in which the incidence of coronary heart disease (CHD) is lower than that in the West. This study aimed to examine the relationship between fibrinogen and other CHD risk factors in Hong Kong Chinese. Fibrinogen was measured by the Clauss method in 1359 men and 1405 women aged 25-74 years, randomly selected from the Hong Kong population. Mean fibrinogen level increased with age, from 2.22 g/l in those aged 25-34 years to 2.76 g/l in 65-74 years in men, and from 2.42 to 2.94 g/l respectively in women. The most important factors associated with fibrinogen were age, obesity and blood lipid levels in both genders. In men, smoking was associated with higher fibrinogen levels and cessation of smoking with lower levels. Prospective studies are needed to examine the role of fibrinogen in CHD in Chinese and other Asian populations.

Adsorption of fibrinogen to droplets of liquid hydrophobic phases. Functionality of the bound protein and biological implications

Fibrinogen adsorbs spontaneously from aqueous media containing that protein to droplets of liquid hydrophobic phases dispersed in those same media. Examples of such phases include mineral oils, straight-chain hydrocarbons, and various plant- and animal-derived oils. Lecithin preexisting on the surface of oil droplets reduces significantly the amount of fibrinogen that can otherwise bind to them. When bound, fibrinogen remains active in the classic sense of fibrin gelation. As a consequence, oil droplets coated with fibrinogen can participate in a host of biologically important adhesive processes in which the protein would be expected to participate. Certain polyanions, eg, heparin, pentosan polysulfate, dextran sulfate, and suramin, bind to adsorbed fibrin(ogen) and prevent thrombin-dependent adhesion of fibrinogen-coated surfaces. Thus, these polyanions can be used to prevent adhesion between fibrin(ogen)-coated oil droplets and other fibrin(ogen)-coated surfaces. Potential practical applications and biological implications of these phenomena are presented and discussed.

Plasma fibrinogen of black South Africans: the BRISK study

OBJECTIVE

To describe the distribution of plasma fibrinogen and relationships with other risk factors for coronary heart disease (CHD) and stroke in the black population of the Cape Peninsula.

DESIGN

A cross-sectional survey of a stratified proportional sample of randomly selected black men and women.

SETTING

Households in Gugulethu, Langa, Nyanga, New Crossroads, KTC, Old Crossroads and Khayelitsha in the Cape Peninsula, South Africa.

SUBJECTS

One subject per household (352 men and 447 women), aged 15-64 years, voluntarily participated. Visitors, pregnant, lactating, ill, mentally retarded and intoxicated subjects were excluded.

RESULTS

Mean fibrinogen (thrombin time coagulation method) of men and women were higher than published data for Europeans but slightly lower than values of black Americans. Women aged 45-54 years had the highest level (3.13+/-0.89 g l(-1)) and men aged 15-24 years had the lowest (2.13+/-0.88 g l(-1)). Fifteen per cent of the men and 12% of the women had a level greater than 1 standard deviation of the mean for their age group. Univariate and multivariate analyses revealed significant (P<0.05) positive correlations of fibrinogen with smoking habit, age, body mass index (BMI), total and low-density lipoprotein (LDL) cholesterol, triglycerides, blood pressure and white blood cell count, and significant negative correlations with high-density lipoprotein (HDL) cholesterol, gamma glutamyl transferase (GGT), serum iron and ferritin. The correlations with BMI, serum lipoproteins, iron, ferritin, and GGT suggest that nutritional status and therefore diet influences plasma fibrinogen.

CONCLUSION

Relatively high fibrinogen levels, tending to cluster with other, including diet-related, risk factors for CHD and stroke, were observed in black South Africans. It is suggested that fibrinogen may contribute to the high stroke incidence of this population group.

Effect of green and black tea supplementation on lipids, lipid oxidation and fibrinogen in the hamster: mechanisms for the epidemiological benefits of tea drinking

There is considerable epidemiological evidence that tea drinking lowers the risk of heart disease. However, the mechanism by which tea can be protective is unknown. Hamsters were fed a normal or high cholesterol diet for 2 weeks and drank green or black tea ad libitum. The plasma lipid profile was significantly improved by both teas compared to controls. Also in vivo lipid oxidation as measured by plasma lipid peroxides and LDL+VLDL oxidizability were significantly decreased by the teas. In the normal fed tea groups fibrinogen was decreased but not in the high cholesterol groups. Green tea was significantly more effective than the black tea. These results show in the hamster model that black and green tea improve the risk factors for heart disease by both hypolipemic and antioxidant mechanisms and possibly a fibrinolytic effect.

von Willebrand factor, fibrinogen and other plasma proteins as determinants of plasma viscosity

Plasma viscosity and fibrinogen are risk factors for cardiovascular disease and on rheological grounds, it is widely believed that the latter is a major determinant of the former. However, other plasma constituents may also be important determinants of plasma viscosity. Our aim was to determine whether or not levels of von Willebrand factor contributed to plasma viscosity. We measured plasma viscosity, fibrinogen, von Willebrand factor, immunoglobulins G, A and M, total, HDL- and LDL-cholesterol, triglycerides and albumin in 95 patients with peripheral arterial disease and in 120 healthy controls. A stepwise multivariate analysis was performed to determine the major influences of plasma viscosity. We also measured fibrinogen, von Willebrand factor, immunoglobulins G, A and M, total, HDL- and LDL-cholesterol, triglycerides, albumin and viscosity in 32 smokers as they successfully progressed to being non-smokers. The level of von Willebrand factor was an independent influence on plasma viscosity in the controls (P < 0.05), patients (P < 0.01) and in the combined group (P < 0.001). von Willebrand factor, fibrinogen and plasma viscosity, but not the immunoglobulins, lipoproteins or albumin, fell (P < 0.05) in smokers as they became non-smokers. We find that von Willebrand factor contributes to plasma viscosity, hence a reduction in levels of von Willebrand factor should result in a reduction in viscosity. These data may have implications for the pathogenesis of cardiovascular disease.

Platelet GP IIIa PlA and GP Ib variable number tandem repeat polymorphisms and markers of platelet activation in acute stroke

A number of polymorphisms of the platelet glycoprotein (GP) Ib-V-IX and IIb/IIIa complexes have been described, and the PlA polymorphism of GP IIIa has been associated with coronary thrombosis. We determined the levels of beta-thromboglobulin (beta-TG) and platelet factor 4 (PF4) and the genotype distributions of PlA and a variable number tandem repeat (VNTR) polymorphism of GP 1b in subjects with acute stroke (n=609) and healthy control subjects (n=435). Levels of beta-TG were higher in patients both initially (47.4 [44.7 to 50.2] ng/mL, P<0.0001) and after 3 months (42.9 [40.3 to 45.7] ng/mL, P=0.03) compared with control subjects (39.4 [37.7 to 41.2] ng/mL). Initial levels of beta-TG were significantly higher in those who subsequently died (58.7 [52.3 to 65.8] ng/mL) compared with those still alive (42.7 [40.1 to 45.5] ng/mL, P<0.0001). In a logistic regression model, beta-TG remained an independent predictor of poststroke mortality, with an odds ratio for an increase in 10 ng/mL of 1.12 (1.03 to 1.21, P=0.006). In subjects who had never smoked, there was a significant difference in the genotype distributions of patients with atherothrombotic stroke (A1/A1=147, A1/A2=70, and A2/A2=2) compared with controls (A1/A1=165, A1/A2=47, and A2/A2=5, P=0.03). The PlA distribution of subjects with atherothrombotic stroke before the age of 50 years (A1/A1=19 and A1/A2+A2/A2=18) was also significantly different from age- and sex-matched controls (A1/A1=54 and A1/A2+A2/A2=20, P=0.02). We found no association of VNTR with stroke or poststroke mortality. These data indicate that there is a persistent state of enhanced platelet activation in subjects with acute stroke, which is associated with poststroke mortality. The increased frequency of the PlA2 allele in young subjects with atherothrombotic stroke lends further support for a role of the PlA polymorphism in acute thrombosis.

Effect of crosslinking by factor XIIIa on the migration of vascular smooth muscle cells into fibrin gels

We evaluated the migration of vascular smooth muscle cells into crosslinked fibrin gels, using an in vitro assay system. Vascular smooth muscle cells from bovine fetal aorta migrated into non-crosslinked and crosslinked fibrin gels and showed a characteristic elongated spindle-shaped appearance with long cytoplasmic processes. The cells displayed two-fold increase in migration into crosslinked fibrin gels compared to non-crosslinked gels, suggesting the importance of fibrin crosslinking by factor XIIIa on its three-dimensional structure for the migration of smooth muscle cells.