Atherosclerosis and the coagulation system

The association between fibrinogen levels and severity of coronary artery disease and long-term prognosis following percutaneous coronary intervention in patients with type 2 diabetes mellitus

Background

Fibrinogen is a potential risk factor for the prognosis of CAD and is associated with the complexity of CAD. There is limited research specifically investigating the predictive role of fibrinogen in determining the severity of CAD among patients with T2DM, as well as its impact on the prognosis following PCI.

Methods

The study included 675 T2DM patients who underwent PCI at the Third People's Hospital of Chengdu between April 27, 2018, and February 5, 2021, with 540 of them remaining after exclusions. The complexity of CAD was assessed using the SYNTAX score. The primary endpoint of the study was the incidence of MACCEs.

Results

After adjusting for multiple confounding factors, fibrinogen remained a significant independent risk factor for mid/high SYNTAX scores (SYNTAX score > 22, OR 1.184, 95% CI 1.022-1.373, P = 0.025). Additionally, a dose-response relationship between fibrinogen and the risk of complicated CAD was observed (SYNTAX score > 22; nonlinear P = 0.0043). The area under the receiver operating characteristic curve(AUROC) of fibrinogen for predicting mid/high SYNTAX score was 0.610 (95% CI 0.567-0.651, P = 0.0002). The high fibrinogen group (fibrinogen > 3.79 g/L) had a higher incidence of calcified lesions and an elevated trend of more multivessel disease and chronic total occlusion. A total of 116 patients (21.5%) experienced MACCEs during the median follow-up time of 18.5 months. After adjustment, multivariate Cox regression analysis confirmed that fibrinogen (HR, 1.138; 95% CI 1.010-1.284, P = 0.034) remained a significant independent risk factor for MACCEs. The AUROC of fibrinogen for predicting MACCEs was 0.609 (95% CI 0.566-0.650, P = 0.0002). Individuals with high fibrinogen levels (fibrinogen > 4.28 g/L) had a higher incidence of acute myocardial infarction (P < 0.001), MACCEs (P < 0.001), all-cause death (P < 0.001), stroke (P = 0.030), and cardiac death (P = 0.002). Kaplan-Meier analysis revealed a higher incidence of MACCEs in the high fibrinogen group (Log-Rank test: P < 0.001).

Conclusions

Elevated fibrinogen levels were associated with increased coronary anatomical complexity (as quantified by the SYNTAX score) and a higher incidence of MACCEs after PCI in patients with T2DM.

Gene Expression Characteristics of Liver Tissue Reveal the Underlying Pathogenesis of Hepatocellular Carcinoma

Background

Hepatocellular carcinoma (HCC) is high-mortality primary liver cancer and the most common malignant tumor in the world. This study is based on a hepatocellular carcinoma-related dysfunction module designed to explore the dysregulation of genes in liver cancer tissue.

Methods

By downloading the relevant data on the GEO database, we performed a differential analysis of healthy liver tissue and liver cancer tissues as well as healthy liver tissue and hepatocellular carcinoma tissue and then obtained two sets of differential genes and combined them. We performed a cointerpretation analysis of these differential genes and constructed related functional disorder modules. A hypergeometric test was performed to calculate the potential regulatory effects of multiple factors on the module, and a series of ncRNA and TF regulators were identified. We obtained a total of 4479 differentially expressed genes in hepatocellular carcinoma, and these genes were clustered into ten hepatocellular carcinoma-related functional interpretation disorder modules.

Results

Enrichment analysis revealed that these modular genes are mainly involved in signal transduction including cell cycle, TGF-beta signal transduction, and p53 signal transduction. Depending on the predictive analysis of multidimensional regulators, 323 ncRNAs and 52 TF-mediated hepatocellular carcinoma-related dysregulation modules were found to regulate disease progression.

Conclusions

Based on a series of investigations, it was found that miR-30b-5p may participate in the peroxisome signal transduction by downregulating ABCD3-mediated module 1, thereby promoting the development and progression of hepatocellular carcinoma. Our research results not only provide a theoretical basis for biologists to study hepatocellular carcinoma further but also offer new methods and new ideas for the personalized care and treatment of hepatocellular carcinoma.

Cardiotonic Pills Plus Recombinant Human Prourokinase Ameliorates Atherosclerotic Lesions in LDLR-/- Mice

Aim

This study was to explore the protective effects of cardiotonic pills (CP) or/and recombinant human prourokinase (proUK)on the atherosclerosis and the potential underlying mechanism.

Methods and Results

Atherosclerosis was induced in LDLR^–/^– mice by high fat diet contained 20% lard and 0.5% cholesterol. Daily oral administration of CP (130 mg/kg) or/and intravenous injection of proUK (2.5 mg/kg, twice a week) began at 8 weeks after feeding with high fat diet and continued for 4 weeks. CP alone treatment markedly decreased plasma triglyceride, but did not ameliorate atherosclerosis plaque. No effect was observed for proUK alone on any endpoints tested. CP plus proUK induced a significantly reduction in the atherosclerotic lesions, along with decreased levels of total cholesterol, triglyceride in the plasma. CP plus proUK inhibited the elevated hepatic total cholesterol and triglyceride in high fat diet-fed LDLR^–/– mice, up-regulating the expressions of ATP-binding cassette gene 5 and 8, and adipose triglyceride lipase. In the aorta, CP plus proUK inhibited the expression of scavenger receptor A and CD36 in LDLR^–/– mice. In addition, we observed that systemic inflammation was inhibited, manifested downregulation of plasma macrophage inflammatory protein-1α and intercellular cell adhesion molecule-1.

Conclusion

CP plus proUK effectively attenuated atherosclerosis plaque in LDLR^–/– mice, which is associated with normalizing the lipid metabolism in the liver and aorta, reducing phagocytosis of receptor-mediated modified-LDL uptake and inhibiting systemic inflammation.

Impact of diabetes on fibrinogen levels and its relationship with platelet reactivity and coronary artery disease: A single-centre study

BACKGROUND

Previous reports have suggested an association between elevated fibrinogen and CAD. Few studies have so far investigated the impact of diabetes on fibrinogen levels and its association with coronary artery disease (CAD) and platelet reactivity in diabetic patients that are therefore the aims of the current study.

METHODS

We measured fibrinogen in 3280 consecutive patients undergoing coronary angiography. Samples were collected at admission for fibrinogen levels assessment. Coronary disease was defined for at least 1 vessel stenosis >50% as evaluated by QCA.

RESULTS

Diabetes was observed in 1201 out of 3280 patients. Diabetic patients were older with more hypercholesterolemia, hypertension, higher BMI, more renal failure, previous MI or coronary revascularization (p<0.001, respectively) and smoking (p=0.001). Diabetic patients were more often on ACE-inhibitors, ARBs, b-blockers, calcium-antagonists, diuretics, statins (p<0.001, respectively), and ASA (p=0.004). Diabetic patients displayed higher glycaemia and HbA1c (p<0.001), higher creatinine and triglycerides (p<0.001) but lower total and HDL cholesterol (p<0.001) and haemoglobin (p<0.001). Diabetic patients had higher fibrinogen levels (p=0.003), however neither diabetes nor glucose homeostasis parameters resulted as independent predictors of hyperfibrinogenemia. Furthermore, among diabetic patients, higher fibrinogen levels did not affect platelet reactivity and were not associated with the prevalence of CAD (adjusted OR[95%CI]=0.99 [0.82-1.19], p=0.9). Similar results were found for severe CAD (adjusted OR[95%CI]=0.94 [0.82-1.08], p=0.40).

CONCLUSIONS

Our study showed that diabetes and glycaemic control are not independent predictors of hyperfibrinogenemia. Among diabetic patients, elevated fibrinogen is not associated with platelet reactivity and the prevalence and extent of CAD.

A study of plasma fibrinogen level in type-2 diabetes mellitus and its relation to glycemic control

The high prevalence of classic cardiac risk factors in patients with type 2 diabetes mellitus does not explain the increased cardiovascular related morbidity and mortality in these patients. Fibrinogen may have a role in this excess risk. This study is undertaken to know the fibrinogen levels in type 2 diabetes mellitus and its relations to glycemic control. In the present study fibrinogen levels (Clauss method) were estimated in 100 type 2 diabetic subjects and 100 age and sex matched controls. Fibrinogen was correlated with various parameters like glycosylated hemoglobin (cation exchange resin method), age, sex, smoking, body mass index (kg/m(2)), hypertension and ischemic heart disease. Higher plasma fibrinogen levels were found in type 2 diabetes mellitus patients (656 ± 130 mg/dl) as compared to controls (324 ± 139 mg/dl) which were statistically significant. Fibrinogen levels were associated with age (P < 0.01), hypertension (P < 0.01), body mass index (P < 0.01), smoking (P < 0.01), ischemic heart disease (P < 0.01), and glycosylated hemoglobin (r = 0.49) in diabetics in a significant manner. But no correlation was found with sex (P < 0.05) in diabetes. In controls, association was found between fibrinogen levels and smoking (P < 0.01) and body mass index (P < 0.01). Patients with type 2 diabetes mellitus had a high prevalence of hyperfibrinogenemia. Fibrinogen levels were independently associated with hemoglobin A1c values, which suggests that fibrinogen may be involved in the increased cardiovascular risk of patients with type 2 diabetes mellitus.

Diabetes mellitus as a prothrombotic condition

Diabetes mellitus (DM) is characterized by fasting hyperglycaemia and a high risk of atherothrombotic disorders affecting the coronary, cerebral and peripheral arterial trees. The risk of myocardial infarction (MI) is 3-5 fold higher in Type 2 DM and a DM subject with no history of MI has the same risk as a non-DM subject with a past history of MI. In total around 70% of deaths are vascular with poorer outcomes to both acute events and cardiological interventions. It was proposed that clustering of vascular risk factors (hyperinsulinaemia, dysglycaemia, dyslipidaemia and hypertension) around insulin resistance (IR) accounted for the increase in risk with Type 2 DM. The importance of this became apparent with the recognition that risk clustering occurs in normoglycaemic and impaired glucose tolerance (IGT) subjects with IR, in total around 25% of the population in addition to long-standing Type 1 subjects with renal disease. Evidence indicates that thrombotic risk clustering also occurs in association with IR, suppression of fibrinolysis due to elevated concentrations of the fibrinolytic inhibitor, plasminogen activator inhibitor-1 (PAI-1) is invariable with IR and there is evidence that this is regulated by the effects of triglyceride on the PAI-1 gene promoter. Other studies indicated that prothrombotic risk (coagulation factors VII, XII and fibrinogen) also associates with the IR syndrome. The development of endothelial cell dysfunction with suppression of nitric oxide and prostacyclin synthesis, combined with platelet resistance to the anti-aggregatory effects of these hormones leads to loss of control over platelet activation. In addition, hyperglycaemia and glycation have marked effects on fibrin structure function, generating a clot which has a denser structure, resistant to fibrinolysis. The combination of increased circulating coagulation zymogens, inhibition of fibrinolysis, changes in fibrin structure/function and alterations in platelet reactivity creates a thrombotic risk clustering which underpins the development of cardiovascular disease.

Reduced clot permeability and susceptibility to lysis in patients with acute coronary syndrome: effects of inflammation and oxidative stress

BACKGROUND

Stable angina is associated with unfavorable fibrin structure/function. It is not known how acute coronary syndromes (ACS) affect fibrin architecture.

OBJECTIVE

We investigated fibrin clot properties and their determinants in ACS patients.

PATIENTS AND METHODS

Clot permeability, turbidity and fibrinolysis were assessed in 40 patients with ACS versus 40 controls with stable angina matched for age, sex, and risk factors.

RESULTS

Patients with ACS had lower clot permeability (p=0.001), faster fibrin polymerization (p=0.008), and prolonged fibrinolysis time (p<0.0001) than controls. C-reactive protein (CRP) and 8-epi-prostaglandin F(2alpha), a marker of oxidative stress, were the only independent predictors of clot permeability (R(2)=-0.74; p<0.0001 and R(2)=-0.65; p<0.0001, respectively) and fibrinolysis time in ACS patients (R(2)=0.60; p<0.0001 and R(2)=0.59; p=0.0002, respectively). In angina patients, fibrinogen and CRP predicted permeability (R(2)=-0.71; p<0.0001 and R(2)=-0.62; p<0.0001), and D-dimer predicted lysis time (R(2)=0.54; p=0.0005). In regression analysis models incorporating all patients, the only independent predictor of all clot variables was being an ACS patient (R(2) 0.51 to 0.85; p<0.001).

CONCLUSIONS

This first study of clot properties in patients during an ACS demonstrated that compared with stable angina patients, their clots are composed of dense networks that are more resistant to lysis and these features are correlated with raised CRP and oxidative stress.

Homocysteine and fibrinogen changes with L-thyroxine in subclinical hypothyroid patients

The aim of the present study was to evaluate plasma total homocysteine (Hcys) and serum fibrinogen concentrations in subclinical hypothyroid (SH) and overt hypothyroid patients before and after L-thyroxine (LT4) replacement and to compare them in euthyroid subjects. Fifteen SH and 20 hypothyroid premenopausal women were recruited in the study. We measured fasting plasma levels of Hcys and serum levels of free thyroxine (fT4), free triiodothyronine (fT3), thyrotropin (TSH), folate, vitamin B12, fibrinogen, renal functions, and lipid profiles in patients with SH and overt hypothyroid patients before and after LT4 treatment. Eleven healthy women were included in the study as a control group. Pretreatment Hcys levels were similar in SH and control subjects, whereas mean fibrinogen level of SH patients was higher than that of control subjects (p<0.05). Baseline Hcys (p<0.01) and fibrinogen (p<0.001) levels of the overt hypothyroid patients were significantly higher than those of the healthy subjects, and the pretreatment Hcys levels decreased with LT4 treatment (p<0.001). In conclusion, our data support that SH is not associated with hyperhomocysteinemia and Hcys does not appear to contribute to the increased risk for atherosclerotic disease in patients with SH.

The influence of type 2 diabetes on fibrin structure and function

AIMS/HYPOTHESIS

The precise mechanisms underlying the increased risk of cardiovascular disease (CVD) in type 2 diabetes are unclear. Fibrin clot structure has been related to CVD risk in the general population. We therefore assessed this in type 2 diabetic patients as a potential mechanism whereby diabetes influences CVD risk.

METHODS

Fibrin clots were formed from fibrinogen purified from 150 subjects with type 2 diabetes and varying degrees of glycaemic control (assessed by HbA1c), and from 50 matched control subjects. Clot structure was assessed by turbidity, permeation and confocal microscopy. The specific effect of glucose itself was assessed by analysing the structure of clots formed from purified fibrinogen in the presence of increasing concentrations of the sugar.

RESULTS

Clots formed by fibrinogen purified from type 2 diabetic subjects had a denser, less porous structure than those from control subjects. The structural changes found were related to the individual's glycaemic control; HbA1c correlated negatively with permeation coefficient (Ks) values (indicates clot pore size) (r = -0.57, p < 0.0001) and positively with maximum absorbance (indicator of fibre size) (r = 0.33, p < 0.0001), branch point number (r = 0.78, p < 0.0001) and fibre density (r = 0.63, p < 0.0001). The ambient glucose level influenced clot structure; hypo- (< 5 mmol) and hyperglycaemia (> or = 10 mmol/l) were both associated with a reduction in Ks values and maximum absorbance, and with increased fibre density and branch point number within clots.

CONCLUSIONS/INTERPRETATION

The structural differences found to occur in type 2 diabetes and in association with hypo- and hyperglycaemia may confer increased resistance to fibrinolysis, and in consequence contribute to the increase in CVD risk in diabetic patients.

Hemostatic system as a risk factor for cardiovascular disease in women with subclinical hypothyroidism

Hypothyroidism has been associated with atherosclerosis. The mechanisms of atherosclerosis in patients with thyroid failure remain controversial. Hypofibrinolysis might be a risk factor for thromboembolic disease in subclinical hypothyroidism (SH). We measured fibrinolytic activity in patients with SH before and after levothyroxine (LT(4)) treatment and compared it to those of controls. We prospectively included 35 patients with SH and 30 healthy controls. We treated patients with LT(4) until almost 6 months after the euthyroid state has been achieved. We measured fibrinogen, D-dimer, antithrombin III (ATIII), plasminogen activator inhibitor-1 (PAI-1), tissue plasminogen activator (tPA) activity, and factor VII. Clinical and anthropometric variables were recorded for both groups. We found increased levels of fibrinogen, PAI-1, and factor VII and decreased levels of ATIII activity in patients compared to control (p < 0.001 and p < 0.05). Decrease of tPA was not significant (p > 0.05). At the end of the LT(4) treatment, significant decreases were determined in PAI-1 and factor VII (p < 0.05). In conclusion, our data suggest an important role of hypofibrinolytic and hypercoagulable state on the development of atherosclerosis in patients with SH and beneficial effects of LT(4 )treatment for decreasing the risk of atherosclerosis.

Effects of lipids on thrombotic mechanisms in atherosclerosis

Cholesterol lowering therapy markedly reduces the frequency of subsequent cardiovascular events and is associated with a modest degree of angiographic regression of atherosclerotic lesions. There is a strong association between lipids and fibrinogen, plasminogen activator-1, and activated factor VII levels. Low density lipoprotein may be thrombogenic whereas high density lipoprotein protects against thrombosis. Lipoprotein (a) may affect atherosclerosis and thrombosis mainly by binding to fibrin and attenuating the fibrin-enhanced plasminogen activation. Tissue factor-complex initiates coagulation by activating factor X and factor IX leading in the presence of calcium to the generation of thrombin. Lipid lowering treatment with statins stabilizes atheromatous plaque and has antithrombotic effects. Therefore there are links between lipids and the haemostatic mechanisms which affect atherosclerotic, vasomotor and thrombotic components of ischemic heart disease.

Prognostic implications of abnormalities in renal function in patients with acute coronary syndromes

BACKGROUND

Outcomes in patients with mild to moderate renal function (RF) abnormalities presenting with acute coronary syndromes (ACS) are not well defined.

METHODS AND RESULTS

A convenience sample of 4 ACS trial databases including all enrolled patients was assessed to determine 30- and 180-day outcomes. The 4 trials were Global Use of Strategies to Open Occluded Coronary Arteries (GUSTO) IIb, GUSTO-III, Platelet Glycoprotein IIb/IIIa in Unstable Angina: Receptor Suppression Using Integrilin Therapy (PURSUIT), and Platelet IIb/IIIa Antagonism for the Reduction of Acute coronary syndrome events in a Global Organization Network (PARAGON-A). Patients were stratified into ST-segment elevation (STE) and non-ST-segment elevation (NSE) groups and by the presence or absence of abnormal RF (creatinine clearance <70 mL/min). In the STE group, 7670 of 18 621 patients (41%) had abnormal RF. In the NSE group, 8152 of 19 304 (42%) had abnormal RF. Patients with abnormal RF were older, more often female, and more likely to have adverse baseline characteristics. They had higher mortality and higher mortality/nonfatal myocardial infarction (MI) at both 30 and 180 days, regardless of ST-segment status. Creatinine clearance was independently associated with risk of mortality (hazard ratio 0.79 in the STE group and 0.81 in the NSE group) and with risk of mortality/MI (hazard ratio 0.93) in the NSE group at 180 days.

CONCLUSIONS

Patients presenting with ACS frequently have abnormal RF. Abnormal RF is a marker of adverse baseline clinical characteristics and is independently associated with increased risk of death and death/MI.

Patients on peritoneal dialysis but not on hemodialysis have elevated concentration and activity of thrombin-activatable fibrinolysis inhibitor

Cardiovascular disease (CVD) is a leading cause of death in patients on dialysis. Increased concentration of fibrinogen, dyslipidemia and impaired fibrinolysis are regarded as important risk factors for CVD. Thrombin-activatable fibrinolysis inhibitor (TAFI) is a recently discovered inhibitor of the fibrinolytic system. The aim of this study was to investigate whether peritoneal dialysis (PD) and hemodialysis (HD) patients differ with regard to TAFI concentration and/or its activity. We also measured albumin, cholesterol, triglycerides and fibrinogen. The study was performed on 35 chronically dialyzed patients (14 on PD and 21 on HD) and 18 healthy volunteers. TAFI antigen and its activity were measured with commercially available kits. Albumin, cholesterol, triglycerides and fibrinogen were measured using standard laboratory methods. Only PD patients had significantly elevated level of TAFI antigen and its activity compared to control subjects. Differences in TAFI concentration and its activity between PD and HD were at the level of statistical significance (P=.09 and P=.07, respectively). PD patients had significantly higher concentration of cholesterol and triglycerides than HD group. Fibrinogen was elevated significantly in PD patients compared to HD and controls. There was no difference in albumin concentration between PD and HD. Significant positive correlations were found between fibrinogen or triglycerides and TAFI activity only in PD patients. We conclude that the above phenomenon may predispose PD patients to suppression of fibrinolysis.

A SAF binding site in the promoter region of human gamma-fibrinogen gene functions as an IL-6 response element

Expression of fibrinogen is highly induced during inflammation, and such abnormal expression of this protein is considered as a major cardiovascular risk factor. IL-6 is one of the main mediators of abnormal expression of fibrinogen leading to the pathogenic conditions. Transient transfection and EMSA were performed to investigate the molecular mechanism of IL-6-induced gamma-fibrinogen gene expression in hepatic cells. Using progressively deleted 5' fragments of the gamma-fibrinogen promoter coupled to chloramphenicol acetyltransferase gene, an IL-6 responsive element located between positions -273 and -259 was identified. Mutation of this element abrogates IL-6 responsiveness of the gamma-fibrinogen promoter. Interaction of this promoter with a zinc finger transcription factor, serum amyloid A activating factor (SAF)-1, was demonstrated by EMSA. Furthermore, overexpression of wild-type SAF-1 in transfected liver cells can increase transcription of the gamma-fibrinogen promoter. These data show that transcription factor SAF-1 is involved in the regulation of IL-6-mediated induction of the human gamma-fibrinogen gene in liver cells.

Plasma and platelet plasminogen activator inhibitor-1 in patients with acute myocardial infarction

Several studies have demonstrated an increased level of plasma plasminogen activator inhibitor-1 (PAI-1) in patients with coronary artery disease (CAD). However, the concentration of PAI-1 in platelets, which accounts for more than 90% of the blood PAI-1, is unknown in these patients. The present study evaluated the concentrations of PAI-1 and several fibrinolytic factors in the plasma and platelets of patients with CAD and the serial changes in patients with acute myocardial infarction (AMI). All 72 subjects had coronary angiography and were divided into 3 groups: CAD(-) group without coronary artery stenosis or myocardial ischemia (n=20), CAD(+) group with either stable angina pectoris (n=18) or old myocardial infarction (n=12) with coronary artery stenosis, and the AMI group admitted within 24h of symptom onset who underwent successful percutaneous transluminal coronary angioplasty (n=22). The concentrations of plasma PAI-1, tissue plasminogen activator (t-PA), and t-PA x PAI-1 complex were similar in the CAD(-) and CAD(+) groups, but were greater on day 1 in the AMI group compared with the 2 CAD groups. There were no significant differences between the 3 groups in the plasma concentrations of thrombin antithrombin III complex (TAT), alpha2-plasmin inhibitor-plasmin complex (PIC), beta-thromboglobulin (beta-TG), and platelet factor 4 (PF-4). The platelet PAI-1 concentrations did not differ between the CAD(-) and CAD(+) groups, but was greater on day 1 in the AMI group compared to the CAD groups. The platelet beta-TG and PF-4 were similar between the 3 groups. In the AMI group, both the plasma and platelet PAI-1 concentrations were greater on day 1, but the plasma PAI-1 rapidly decreased by day 5 and remained low on day 28 compared with day 1. The platelet PAI-1 concentration gradually decreased by day 5 and was further decreased by day 28. The serial changes of the plasma t-PA and t-PA PAI-1 complex during the course of AMI were similar to those of the plasma PAI-1. A positive correlation was found between the plasma and platelet PAI-1 in all 72 patients, but not in the AMI group alone. These results suggest that the PAI-1 that has accumulated in platelets at the onset of AMI might be released in large amounts into the plasma, resulting in an increase in thrombus formation.

Simvastatin attenuates vascular hypercoagulability in cardiac transplant recipients

BACKGROUND

3-Hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors have been shown to reduce cardiac allograft failure and to lower the incidence of transplant coronary artery disease. These effects result from as yet unknown mechanisms not clearly attributable to lipid lowering. We here report that low-dose simvastatin treatment inhibits excessive expression of monocyte tissue factor (TF) and reduces the persistent hypercoagulability state seen in cardiac transplant recipients.

METHODS

Fifteen consecutive heart transplant recipients receiving standard oral immunosuppression were newly assigned to a 10 mg daily simvastatin therapy. Levels of TF activity in both unstimulated and lipopolysaccharide-stimulated peripheral blood mononuclear cells drawn from transplant recipients before and under simvastatin therapy were evaluated by one-stage clotting assay.

RESULTS

Monocyte TF activity was found to be significantly increased in cardiac transplant recipients when compared with healthy controls. Excessive monocyte procoagulant activity was reduced in cardiac transplant recipients during simvastatin treatment. This effect occurred independently of the reduction of serum low-density lipoprotein cholesterol. As demonstrated by reverse transcriptase-polymerase chain reaction, monocyte TF reduction by simvastatin, observed in 13 of the 15 transplant recipients investigated, could be ascribed to an inhibition of monocyte TF gene transcription. The reduction of monocyte TF activity during treatment with simvastatin paralleled with the normalization of elevated levels of thrombin-antithrombin complex, prothrombin fragment F1+2, and D-dimer, which are markers of thrombin and fibrin formation indicating coagulation activation after cardiac transplantation.

CONCLUSION

Inhibition of monocyte TF expression and attenuation of the persistent hypercoagulable state observed in cardiac transplant recipients during treatment with simvastatin may represent an important mechanism by which HMG-CoA reductase inhibitors protect against the development of transplant coronary artery disease.

Relationship between plasma plasminogen activator inhibitor 1 and insulin resistance

High plasminogen activator inhibitor 1 (PAI-1) levels are associated with an increased cardiovascular risk of atherothrombosis. Furthermore, increased plasma PAI-1 levels are associated with dyslipidemia, hyperinsulinemia and hypertension. This association between PAI-1 and metabolic components of the Metabolic Syndrome could explain the predisposition of insulin resistant patients to atherothrombosis. Recent studies have suggested that visceral adipose tissue might be the link between elevated plasma PAI-1 and insulin resistance in the Metabolic Syndrome. Indeed, visceral adipose tissue was proposed as a potentially important source of PAI-1 in humans. However, in light of recent studies, visceral adipose tissue appears to be involved in the increase of plasma PAI-1 via the metabolic disorders usually associated with central obesity, rather than directly. High plasma PAI-1 levels are undoubtedly related to insulin resistance, and the mechanisms which could explain such an increase in the Metabolic Syndrome appear to be multi-factorial and remain to be elucidated. These mechanisms may involve several metabolic disorders such as hyperinsulinemia, dyslipidemia, impaired glucose tolerance and hypertension, which would favor PAI-1 synthesis and release from different cell types.

Inflammatory and hemostatic markers in relation to cardiovascular prognosis in patients with stable angina pectoris. Results from the APSIS study. The Angina Prognosis Study in Stockholm

Increased inflammatory activity and platelet activation have been associated with an increased risk of cardiovascular (CV) events in epidemiological studies, but their prognostic importance in patients with stable angina pectoris is less well established. The Angina Prognosis Study in Stockholm (APSIS), comprised 809 patients (2766 patient years) with stable angina pectoris on double-blind treatment with verapamil or metoprolol. Plasma levels of fibrinogen and orosomucoid (an acute phase reactant), white blood cell counts (WBC), platelet counts and the urinary excretion of beta-thromboglobulin (reflecting platelet secretion), were related to the risk of CV death (n=36), non-fatal myocardial infarction (MI) (n=30) or revascularization (n=99) in a subgroup of 782 patients. Verapamil and metoprolol had only minor effects on the inflammatory variables. In multivariate Cox regression analyses (adjusted for previous MI, hypertension, diabetes mellitus and smoking), fibrinogen and WBC were independent predictors of CV death or non-fatal MI, as well as the risk of revascularization. Orosomucoid did not carry any independent information. Platelet counts and urinary beta-thromboglobulin were not significantly related to CV prognosis. The treatment given did not significantly influence the prognostic impact of either fibrinogen or WBC. Fibrinogen and WBC were independent predictors of CV death or non-fatal MI as well as disease progression leading to revascularization in patients with stable angina pectoris. As fibrinogen is also an acute-phase reactant, the present findings indicate that inflammatory activity is involved in disease progression in stable angina pectoris.

Plasma plasminogen activator inhibitor 1, insulin resistance and android obesity

Plasma plasminogen activator inhibitor 1 (PAI-1) levels are elevated in insulin-resistant subjects and are associated with increased cardiovascular risk of atherothrombosis. Strong association between PAI-1 and the metabolic components of the insulin resistance syndrome is found in clinical studies, suggesting that insulin resistance may regulate circulating PAI-1. However, the mechanisms underlying increased PAI-1 levels in such conditions are still poorly understood. Several studies have been carried out specifically in patients with central or android obesity, a major characteristic of the insulin resistance syndrome, and have suggested that visceral adipose tissue may be the major component of the relationship between android obesity and PAI-1. Accordingly, adipose tissue PAI-1 production was found to be elevated in obese human subjects, particularly in visceral adipose tissue. The genetic background for having high PAI-1 levels in several populations have been looked for and its role appeared to be weaker than that of the metabolic condition. High plasma PAI-1 levels are then clearly related to android obesity and insulin resistance, but the mechanisms whereby PAI-1 increases in plasma in these diseases remain to be determined.

Fibrinolysis and thrombosis

The fibrinolytic system generates plasmin, which dissolves fibrin in haemostatic plugs and in thrombi. It is often regarded simply as a secondary phenomenon responsive to the generation of thrombi but it is, rather, in dynamic balance with fibrin formation, such that abnormalities in either can lead to thrombosis. This chapter summarizes the fibrinolytic system and its regulation. It considers the components of the system in blood, both in plasma and in circulating cells, with emphasis on protease-inhibitor balance. It goes on to discuss local fibrinolytic potential in thrombi, both venous and arterial, and in the diseased vessel wall, presenting evidence that increased local inhibition of fibrinolysis by PAI-1, PAI-2 and alpha2-antiplasmin is intimately involved in thrombus stability and in the generation of fibrin-rich vessel wall lesions. Finally, it reviews the evidence that defective plasma fibrinolysis has a causal role in venous and arterial thrombosis.

In situ detection of tissue factor within the coronary intima in rat cardiac allograft vasculopathy

Cardiac allograft vasculopathy is a major cause of morbidity and mortality of cardiac transplant recipients. The underlying cause of this disease remains unclear. Histological studies have implicated accelerated hemostasis and intravascular fibrin deposition in its pathogenesis. In the present study a defined model of this disease in the rat was used to elucidate the implication of tissue factor in the production of the hypercoagulable state observed in cardiac allograft vessels. Tissue factor protein and mRNA expression were studied in rat heart allografts developing allograft vasculopathy resembling human disease. Immunohistochemistry demonstrated tissue-factor-positive cells present in the allograft coronary intima and adventitia. Significant staining for tissue factor was detected in the endothelium lining coronary lesions in cardiac allografts and in interstitial mononuclear cells, respectively. Both transplant coronary endothelial cells and mononuclear cells contained tissue factor mRNA as indicated by oligo-cell reverse transcription polymerase chain reaction after laser-assisted cell picking. In contrast, tissue factor mRNA and protein were not or negligibly detectable within the coronary intima of nontransplanted control hearts. Thus, the present study clearly demonstrates that aberrant tissue factor expression occurs within the coronary intima after cardiac transplantation. Tissue factor, activating downstream coagulation mechanisms, may account for the intravascular clotting abnormalities observed in cardiac allografts and may represent a key factor in transplant atherogenesis.

The effects of structurally defined triglycerides of differing fatty acid composition on postprandial haemostasis in young, healthy men

The aim of this study was to investigate whether a number of key haemostatic factors were altered when healthy young individuals were challenged with a fat load of physiological size contained within a meal composed of normal ingredients and whether this response was modified when the fatty acid composition of the meal was altered radically. Eight healthy male volunteers each randomly consumed four meals which were identical in terms of gross nutritional content (41% of energy provided as fat, 17% as protein and 42% as carbohydrate) but which differed in fatty acid composition. To reduce the possible influence of fatty acid position within the triglyceride molecule on lipid absorption and subsequent metabolic effects, the structural integrity of 91% of fat (test triglycerides such as 1,3 distearoyl-2-oleoyl glycerol (S-O-S), trioleine (O-O-O), and 1,3 dilinoleoyl-2-oleoyl glycerol, (L-O-L)) in the meals was controlled so that the principal fatty acid in the sn-2 position was oleic acid (18:1n-9). Meals rich in either a test triglyceride or a control oil provided 44+/-6 g of fat. No significant alterations from fasted values of elevated plasma factor VII coagulant activity (FVIIc) or F1 + 2 were observed. FVIIA varied significantly over the postprandial time course; however, when expressed as a percentage of the fasting value, the FVIIa responses to O-O-O and L-O-L differed significantly but this was not evident when the absolute values were analysed. Similarly, no difference in plasma fibrinopeptide A (FPA) concentrations were evident. After all four meals, chylomicron contained proportionately more palmitic acid and generally less oleic acid than the ingested lipids. This study clearly demonstrates that postprandial haemostatic responses of young healthy individuals to a physiological fat load are minimal, (irrespective of triglyceride structure).

Fibrinogen and cardiovascular risk

The hypothesis that fibrinogen is closely related to cardiovascular risk has been strengthened through the results of various lines of research, which this review will aim to unravel. Several prospective epidemiological studies convincingly show elevated fibrinogen to represent a major, independent cardiovascular risk factor. Cross-sectional studies strongly associate fibrinogen and conventional cardiovascular risk factors. Clinical cohort studies demonstrate that increased fibrinogen is also a risk factor for the sequelae of cardiovascular disease. Our knowledge about the determinants of the variable plasma level of fibrinogen in health and disease is incomplete. Understanding of the mechanisms that might be involved in the atherothrombogenic action of fibrinogen is also fragmentary. Fibrinogen strongly affects blood coagulation, blood rheology and platelet aggregation. In addition, it has direct effects on the vascular wall and is a prominent acute phase reactant. All of these phenomena might constitute pathophysiological mechanisms involved in the association between fibrinogen and cardiovascular events. Their relative importance is unclear at present. Even though many crucial questions await conclusive answers, little doubt exists that fibrinogen represents a major, independent risk factor.

Exercise and heart disease: cardiac findings in fatal cycle accidents

BACKGROUND

Regular cyclists have been found to have a lower incidence of coronary events (CHD) than the general public. Non-invasive studies have found that competitive cyclists develop a cardiac hypertrophy that is physiological and reversible.

METHODS

To obtain pathological support for these observations, the postmortem findings of 32 cyclists killed in accidents have been compared with those in a control group of 32 other road traffic accidents, which were matched with the cyclists by sex, age, and year of death.

FINDINGS

Large myocardial scars and complete blockage of a coronary artery were only found in the controls; serious stenoses of coronary arteries (> 50%) were found in eight controls but in only one of the cyclists. Of the cyclists, 25 had normal coronary arteries as compared with 14 of the controls. The mean age of the cyclists with evidence of CHD was greater than that of similarly affected controls. The heart weights of the two groups were almost the same but heart weight varied with the degree of CHD. The heart weight of the healthy cyclists (389 g) was greater than that of the healthy controls (371 g) but this was not statistically significant.

INTERPRETATION

The results are in keeping with the concept that regular exercise provides some protection from the development of CHD and that cycling may be a valuable form of exercise in this respect. This may be of importance as the number of physically active occupations declines.

Haemostasis balance disorders in patients with essential hypertension

This study was aimed at investigating haemostasis parameters in patients (pts) with arterial hypertension (AH) before any medical treatment and to correlate these findings with those in healthy normal Greek population 83 pts (48 m, 35 w) mean age 49.8 +/- 10.1 yrs, body mass index 23.4 +/- 1.5 with mild to moderate AH and 42 healthy volunteers matched for sex (24 m, 18 w), age 51.2 +/- 10.5 yrs and body mass index 22.8 +/- 1.46 were studied. Fibrinogen, vWF, plasminogen, ECLT, a2 antiplasmin, tPA-Ag, PAI-1 in all pts and in the control group were measured. Mean age and BMI did not significantly differ between the two groups. The hypertensive patients had significantly higher levels of fibrinogen (327.75 +/- 51.36 vs. 272.84 +/- 46.8 mg/dl), tPA-Ag (8.81 +/- 3.32 vs. 5.76 +/- 2.54 ng/ml) and PAI-1 (11.8 +/- 10.9 vs. 7.91 +/- 5.5 IU/ml), whereas a2 antiplasmin level was significantly lower (98.71 +/- 15.40 vs. 107.84 +/- 17.52%). No differences were found between hypertensives and normal subjects in vWF, plasminogen and ECLT. These preliminary data suggest that in pts with mild to moderate AH, before any medical treatment, there are significantly higher levels of fibrinogen, tPA-Ag and PAI-1 compared with normal volunteers, whereas there are significantly lower a antiplasmin levels. These findings indicate a disturbance in the haemostasis balance with hypercoagulability and fibrinolytic deficiency.

Cytomegalovirus infection, lipoprotein(a), and hypercoagulability: an atherogenic link?

A link between cytomegalovirus (CMV) infection and atherosclerosis has been suggested by experimental, clinical, and epidemiologic studies. We investigated the association between CMV antibody titers in serum collected in 1974 in 300 adult residents in Washington County, Md, and hemostatic parameters in plasma collected in 1987 through 1989, when these individuals participated in the baseline examination of the Atherosclerosis Risk in Communities Study. The cross-sectional association of CMV serum antibodies and hemostatic parameters was also explored in another set of Atherosclerosis Risk in Communities cases and controls. In the longitudinal analyses, CMV titers in 1974 were directly associated with 1987 through 1989 plasma levels of von Willebrand factor, factor VIII, and protein C and negatively associated with activated partial thromboplastin time. In the cross-sectional analyses, CMV titers were directly related to antithrombin III and fibrinogen levels. When the association between CMV antibodies and atherosclerosis was examined in stratified analyses, a significant association was restricted to individuals with high levels of lipoprotein(a) and fibrinogen. These results are compatible with previous evidence suggesting that CMV virus might have procoagulant properties. The possible synergism of CMV infection and resulting hypercoagulability with reduced fibrinolysis due to increased lipoprotein(a) levels deserves further investigation.

Plasma fibrinogen concentration in a Chinese population

Plasma fibrinogen concentration has been shown to be a predictor of major cardiovascular events. Information on plasma fibrinogen amongst Chinese has been scanty. We examined the relationships between plasma fibrinogen concentration and cardiovascular risk factors in 988 chinese subjects who underwent 75 g oral glucose tolerance test for screening for glucose intolerance. The study involved a selected sample with subjects who had an history of gestational diabetes, delivery of big babies (birth weight > or = 4 kg), equivocal plasma glucose concentrations and subjects who were family members of diabetic patients. This was mainly a non-smoking (96.6%), non-drinking (98%) and non-exercising (99%) population of which 87% (n = 855) were female. Among the 988 subjects (age +/- S.D. 36.8 +/- 10.2, range 16-79 years), plasma fibrinogen concentration ranged from 1.40 to 9.90 g/l with a mean of 3.26 +/- 0.93 g/l. On stratification of the subjects into 4 quartiles based on plasma fibrinogen concentrations, we found that increased plasma fibrinogen was associated with older age, higher body mass index (BMI), systolic and diastolic blood pressure (BP), fasting and 2 h plasma glucose (PG), prevalence of diabetes, glycated haemoglobin (HbA1c) and triglyceride (TG) level. After adjustment for age and sex, increased plasma fibrinogen concentration remained associated with higher BMI, systolic BP, 2 h PG and TG level. On multivariate analysis using age, BMI, BP, TG, HbA1c and PG as independent variables, plasma fibrinogen was independently related to plasma TG concentration and HbA1c. With 1 S.D. change in TG concentration and HbA1c, there were 3.7 and 5.2% changes in plasma fibrinogen concentration respectively. These findings emphasize the close relationships between plasma fibrinogen and cardiovascular risk factors, in particular abnormal lipid and glucose metabolism.

Resistance of gammaA/gamma' fibrin clots to fibrinolysis

Elevated plasma fibrinogen levels are a major risk factor for thrombosis. This report shows two mechanisms by which fibrinogen can affect the fibrinolysis rate in vitro and thus may lead to thrombosis. First, the lysis rate of fibrin decreases as the initial concentration of fibrinogen increases. Second, a minor variant form of fibrinogen decreases the rate of fibrinolysis. This variant, gammaA/gamma' fibrinogen, has one altered gamma chain and is known to bind to factor XIII zymogen. In a fibrinolysis assay containing purified thrombin, fibrinogen, tissue-type plasminogen activator, and plasminogen, clots from gammaA/gammaA and gammaA/gamma' fibrinogen lysed at similar rates. However, when factor XIII was added, slower lysis was seen in gammaA/gamma' fibrin clots when compared with gammaA/gammaA fibrin clots. A D-dimer agglutination assay showed that the gammaA/gamma' clots were more highly cross-linked than the gammaA/gammaA clots. The lysis rates of gammaA/gamma' clots were similar to gammaA/gammaA clots in the presence of N-ethylmaleimide, a specific inhibitor of factor XIIIa. The gammaA/gamma' fibrin clots made in the presence of factor XIII showed increased proteolytic resistance to both plasmin and trypsin. Clots made from afibrinogenemic plasma reconstituted with gammaA/gamma' fibrinogen also showed significant resistance to lysis compared with gammaA/gammaA fibrinogen. These data demonstrate gammaA/gamma' fibrin is resistant to fibrinolysis, possibly as a result of concentrating factor XIII on the clot. The total fibrinogen concentration and the amount of gammaA/gamma' fibrinogen increase clot stability in vitro and thus may contribute independently to the risk of thrombosis in humans.

Ten-year follow-up results from the Goettingen Risk, Incidence and Prevalence Study (GRIPS). I. Risk factors for myocardial infarction in a cohort of 5790 men

Besides the accepted major risk factors for myocardial infarction (MI), cholesterol, hypertension and smoking, several other variables such as lipoproteins, apolipoproteins, fibrinogen and family history of MI, have been considered, but their usefulness as predictors of MI is controversially discussed. The Göttingen Risk Incidence and Prevalence Study (GRIPS) aimed to evaluate the independent impact of the latter in comparison to the established risk factors. GRIPS is a prospective cohort study, which included 5790 men, aged 40-59.9 years, without cardiovascular disease at baseline. Multivariate logistic regression models for the estimation of the MI risk based on the 10-year follow-up data from 97.4% of the study participants established LDL cholesterol as the strongest predictor of MI. It was followed by family history of MI, Lp(a), age, smoking, systolic blood pressure, HDL cholesterol (inversely related) and plasma glucose (P < 0.001). Apolipoprotein B as well as the ratios total/HDL cholesterol, LDL/HDL cholesterol and Apo B/AI were less effective predictors than LDL cholesterol and did not contribute independently to the estimation of MI risk. Similarly apoprotein AI was a weaker predictor of MI risk then HDL cholesterol. GRIPS is the first prospective cohort study which clearly justifies the key role of LDL cholesterol in preventive strategies. However, the data also give strong support for the additional consideration of other risk factors for a valid estimation of the MI risk for an individual subject.

Fibrinogen levels in women having coronary angiography

Fibrinogen has emerged as a risk factor for coronary artery disease in men that equals cholesterol in importance. It is known to play an important role in reparative processes, and evidence is accumulating that fibrinogen/fibrin accumulates at the site of minimal vascular injury. Fibrinogen contributes significantly to blood viscosity and its adherence to endothelium may mediate progression of atheromatous lesions. This study was designed to examine a number of markers of risk in a consecutive series of cardiology patients undergoing coronary catheterizations over a 15-month period. This article examines the level of fibrinogen in relation to the number of reported coronary stenoses and disease severity in a series of Caucasian female patients (n = 101). Women were classified as diseased if they had at least 1 lesion > or = 25% in the coronary anatomy and nondiseased if they had no lesions > or = 25%. The number of reported lesions correlates significantly with fibrinogen levels (r = 0.36, p = 0.0002). Women with fibrinogen levels > or = 283 mg/dl had a 3.2-fold increased risk (95% confidence interval 1.2 to 9.1) of having at least 1 stenosis > or = 25% after adjusting for age and diabetic status. Smoking and body mass index did not differ by disease status and thus did not confound the finding. Mean fibrinogen levels showed a progressive positive association with increasing clinically defined vessel involvement (stenosis > or = 50%).

No influence of proinsulin and insulin on plasma levels of plasminogen activator inhibitor type 1 and tissue plasminogen activator in young women before and during intake of contraceptive steroids

Clinical observations in patients predisposed to cardiovascular disorders and recent experimental observations suggest that proinsulin and insulin participate in the regulation of fibrinolysis in vivo. In the present study, we examined if proinsulin and insulin affect the constitutive (fasting) secretion of plasminogen activator inhibitor type 1 (PAI-1) and tissue plasminogen activator (t-PA) in young healthy women (N = 17). We also measured the antigen concentrations of PAI-1 and t-PA during slow and fast changes in proinsulin and insulin levels induced by oral (OGTT) and intravenous (IVGTT) glucose tolerance tests. The assessments were performed before and after 6 months of treatment with contraceptive steroids, which have a well-defined influence on the fibrinolytic variables. We observed no consistent correlations between fasting values of proinsulin, insulin, PAI-1, and t-PA either before or during hormonal treatment. Before hormonal treatment, PAI-1 and t-PA antigen levels decreased (P < .05) during the hyperproinsulinemia and hyperinsulinemia induced by the OGTT and IVGTT. After hormonal intake for 6 months, a decrease only in t-PA concentrations during the OGTT was observed despite similar proinsulin and insulin responses to the glucose loads. Our findings suggest that proinsulin and insulin have no influence on the regulation of plasma levels of PAI-1 and t-PA in young healthy women, irrespective of intake of contraceptive steroids.

Fish oil may be an antidote for the cardiovascular risk of smoking

The fact that the cardiovascular risk of ex-smokers approximates that of non-smokers after two years of abstinence, implies that accelerated atherogenesis is not the chief mechanism of smoking-related heart disease. Indeed, smoking or nicotine have adverse effects on blood rheology, thrombotic risk, coronary blood flow, and risk for arrhythmias. Omega-3-rich fish oils can be expected to correct or compensate for a remarkable number of the adverse impacts of smoking/nicotine: increased plasma fibrinogen, decreased erythrocyte distensibility, increased plasma and blood viscosity, increased platelet aggregability, increased plasminogen activator inhibitor levels, vasoconstriction of the coronary bed, reduced fibrillation threshold, increased triglycerides, reduced high-density lipoprotein cholesterol, and increased production of superoxide by phagocytes. Smokers who cannot overcome their addiction should be encouraged to substitute nicotine aerosols/gum for tobacco and advised to use supplementary fish oil and other cardioprotective nutrients.

The role of lipoprotein(a) in atherogenesis and thrombosis

Lipoprotein(a) [Lp(a)] represents an important independent risk factor for atherosclerotic cardiovascular disease. Lp(a) constitutes a class of low-density lipoprotein-like particles that are structurally heterogeneous due to variability within the distinguishing apoprotein, apolipoprotein(a) [Apo(a)]. Apo(a) bears a high degree of homology to the fibrinolytic zymogen, plasminogen, the parent molecule of the serine protease plasmin. Apo(a) contains a variable number of tandemly repeated triple-loop units called kringles, which appear to mediate Lp(a)'s interactions with fibrin and cell surface receptors. Although the mechanism of its atherogenicity is unknown, Lp(a) has been implicated in the delivery of cholesterol to the injured blood vessel, in blockade of plasmin generation on fibrin and cell surfaces, and as a stimulus for smooth muscle cell proliferation. In addition, new members of the plasminogen/Apo(a) gene family have been defined, creating a potential link between Lp(a) and the control of angiogenesis in both health and disease. Pharmacologic therapy of elevated Lp(a) levels has been only modestly successful; apheresis remains the most effective therapeutic modality.

Elaboration of type-1 plasminogen activator inhibitor from adipocytes. A potential pathogenetic link between obesity and cardiovascular disease

BACKGROUND

Obesity is known to predispose to attenuated fibrinolysis attributable to increased concentrations in plasma of type-1 plasminogen activator inhibitor (PAI-1), the primary physiological inhibitor of endogenous fibrinolysis. PAI-1 is present in neointimal vascular smooth muscle cells and lipid-laden macrophages.

METHODS AND RESULTS

The present study was designed to determine whether PAI-1 expression occurs in adipose tissue as well, thereby potentially contributing to increased cardiovascular risk associated with obesity. 3T3-L1 preadipocytes were differentiated into adipocytes by exposing them to isobutylxanthine (0.5 mmol/L) and dexamethasone (0.25 mumol/L) over 7 days and incubated for 24 hours with transforming growth factor-beta (TGF-beta), known to augment PAI-1 synthesis in several cell types and to be released from platelets when they are activated. TGF-beta increased PAI-1 activity in the conditioned media of the 3T3-L1-derived cells in a concentration-dependent fashion without significantly affecting cell proliferation. Western blotting and immunoprecipitation of 35S-labeled PAI-1 showed that the increased PAI-1 activity paralleled increased PAI-1 protein. Northern blotting showed that increased PAI-1 mRNA preceded increased accumulation of PAI-1 activity and protein in the conditioned media. Furthermore, TGF-beta (10 ng/g body wt) administered in vivo increased PAI-1 activity in mouse plasma and PAI-1 mRNA expression in mouse adipose tissue.

CONCLUSIONS

Increased plasma PAI-1 activity in obese human subjects may result from PAI-1 release from an increased mass of adipose tissue, particularly in association with thrombosis and elaboration of TGF-beta from platelet alpha-granules into the circulation. The increased PAI-1 may exacerbate vascular disease by shifting the balance between thrombosis and thrombolysis toward thrombosis and consequently exposing luminal surfaces of vessels to mitogens associated with microthrombi over protracted intervals.

Monounsaturated fatty acid-enriched diet decreases plasma plasminogen activator inhibitor type 1

An increase in levels of plasma plasminogen activator inhibitor type 1 (PAI-1) is one of the main hemostatic alterations in patients with coronary heart disease. Despite growing interest in the fibrinolytic system, few studies have been undertaken to determine the effect exerted on it by the different dietary fatty acids. We investigated the effect of a monounsaturated fat (MUFA)-rich diet in comparison with a low-fat diet (National Cholesterol Education Program step 1 diet) (NCEP-1) on factors involved in blood coagulation and fibrinolysis. We also determined the effect of dietary cholesterol on these blood parameters. Twenty-one young, male, healthy volunteers followed two low-fat/high-carbohydrate diets (< 30% fat, < 10% saturated fat, 14% MUFA) for 24 days each, with 115 or 280 mg of cholesterol per 1000 kcal per day, and two oleic acid-enriched diets (38% fat, 24% MUFA) with the same dietary cholesterol as the low-fat/high-carbohydrate diets. Plasma levels of fibrinogen, thrombin-antithrombin complexes, prothrombin fragments 1+2, plasminogen, alpha 2 antiplasmin, and tissue plasminogen activator were not significantly different among the experimental diets used in this study. Consumption of the diet rich in MUFA resulted in a significant decrease in both PAI-1 plasma activity (P < .005) and antigenic PAI-1 (P < .04) compared with the carbohydrate-rich diet (NCEP-1). The addition of dietary cholesterol to each of these diets did not result in any significant additional effect. Changes in insulin levels and PAI-1 activity were positively correlated (r = .425; P < .02). In conclusion, consumption of diets rich in MUFAs decreases PAI-1 plasma activity, which is accompanied by a parallel decrease in plasma insulin levels.

Levels of factor VIIc associated with decreased tissue factor pathway inhibitor and increased plasminogen activator inhibitor-1 in dyslipidemias

Tissue factor pathway inhibitor (TFPI), a kunitztype inhibitor of the extrinsic coagulation pathway, factor VII coagulant (FVIIc), FVIIa, and the fibrinolytic factors plasminogen activator inhibitor-1 (PA1-1) and tissue plasminogen activator (TPA) have been studied in various hyperlipidemias. Compared with a normal lipidic group, mean TFPI activity was 70% higher (P < .001) and 36% higher (P < .001) in type IIa and IIb hyperlipidemias, respectively, and was lower by 13% in type IV hyperlipidemia (P = .05). TFPI was correlated with LDL cholesterol (P < .001), total cholesterol (P < .001), HDL cholesterol (P < .01), apolipoproteins (apo) AI (P < .001) and B (P < .001) and lipoprotein a (P < .01). TFPI was negatively correlated with the triglyceride level (P < .05); the correlation was dependent on LDL cholesterol and HDL cholesterol levels, which were decreased in type IV hyperlipidemia. FVIIc activity (P < .001) was increased by 30% in both type IV and type IIb hyperlipidemia and was correlated with triglyceride levels. FVIIa was not significantly increased in any group compared with control group. FVIIc was correlated with triglyceride level (P < .001), while FVIIa was not. Interestingly, FVIIa was correlated with FVIIc (r = .5, P < .001) in the control group as well as in the hyperlipidemic groups (r = .32, P < .01). These results favor the hypothesis that higher FVIIc concentrations in hyperlipidemic patients are likely due to enhancement of synthesis of FVII and that a part of this FVII circulates in an activated chemical form. Compared with the control group, PAI-1 activity was twofold higher (P < .08) in type IIa hyperlipidemia, threefold higher (P < .001) in type IIb hyperlipidemia, and fourfold higher in type IV hyperlipidemia (P < .001). PAI-1 activity correlated with triglyceride levels (P < .001), apoB levels (P < .001) and total cholesterol levels (P < .05). These correlations were dependent on apoB and probably reflect the correlation between PAI-1 and VLDL. In contrast, TPA level was normal in the different hyperlipidemias. No correlation was found between TFPI, FVIIc, and PAI-1. Variation of TFPI activity appears to be related to the variations of its main lipoprotein carriers: LDL, HDL, and Lp (a). The association in hypertriglycemic patients of hypercoagulability (increased FVIIc and decreased TFPI) and hypofibrinolysis (increased PAI-1) may explain thrombosis predisposition of some of these patients. However, it would be interesting to study the increased levels of endothelium-derived TFPI in plasma induced by the injection of heparin.

Fibrinogen and silent atherosclerosis in subjects with cardiovascular risk factors

Fibrinogen may play an active role in the development and progression of atherosclerotic plaques. We assessed the association between fibrinogen levels and atherosclerotic plaques over three different arterial sites in an asymptomatic never-treated male population with increased cardiovascular risk. We included 652 men aged 40 to 60 years old with at least one of the following cardiovascular risk factors: cholesterol > 6.2 mmol/L and/or systolic blood pressure > or = 160 mm Hg and/or diastolic blood pressure > or = 95 mm Hg, and/or because they smoked. Carotid and femoral arteries and the abdominal aorta were assessed by using ultrasonographic methods for the presence of plaque, and subjects were categorized according to the presence (or absence) and extent (one versus two or three sites) of plaque. Plasma fibrinogen was measured according to the thrombin-time method of Clauss. While the presence of atherosclerosis was significantly related to age, current smoking, systolic pressure, LDL cholesterol, and fibrinogen levels, the extent of atherosclerosis was related to age and triglyceride and fibrinogen levels. Multiple regression analysis indicated independent associations between fibrinogen and the presence and extent of atherosclerosis. Plaque prevalence was significantly more pronounced with increasing tertile of fibrinogen levels. The odds ratio of the upper to lower fibrinogen tertiles for the presence of plaque was 1.6 (95% confidence interval, 1.4 to 1.8) and 1.4 (95% confidence interval, 1.2 to 1.7) for its extent. Adjustment for other risk factors slightly reduced the association between fibrinogen and atherosclerosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Evidence against hypercoagulability in coronary artery disease

The strong epidemiological association between elevated plasma clotting factors and coronary artery disease is generally interpreted as evidence that patients with coronary atherosclerosis are in a procoagulant (hypercoagulable) state. A dynamic global test was used to assess the overall coagulation status of 761 patients with coronary artery disease scheduled for coronary artery bypass grafting and compared to healthy matched controls (n = 100). Platelet reactivity to shear-stress was simultaneously measured from identical, non-anticoagulated blood samples. Contrary to expectation, the overall coagulation in cardiac patients did not differ significantly from that of controls. Furthermore, the coagulation status of patients bore no relationship to the severity of coronary atherosclerosis. The latter is in contrast with platelet reactivities, which were significantly increased in patients with > or = 2 vessel disease as compared with single vessel disease. The present results do not necessarily conflict with the finding of elevated plasma clotting factors in cardiac patients. However, they do not support the claim that these markers are a reflection of a hypercoagulable state. Indeed, this study confirms that such patients are in a prothrombotic state, which is related to enhanced platelet reactivities, and not to a prothrombotic imbalance of the coagulation mechanism.

Tissue-plasminogen activator, plasminogen activator inhibitor and risk of peripheral arterial disease

In this population-based case-control study, we examined the relationship between the fibrinolytic variables tissue-plasminogen activator (t-PA) antigen and plasminogen activator inhibitor (PAI) activity, cardiovascular risk factors and peripheral arterial disease. Cases and controls were selected from the Edinburgh Artery Study, a random sample survey of men and women, aged 55-74 years. Mean levels of t-PA antigen and PAI activity were significantly elevated in 121 cases compared to 126 controls. The increased risks of peripheral arterial disease with increasing PAI activity and t-PA antigen levels were partly mediated by interactions with serum triglycerides, high density lipoprotein (HDL) cholesterol and cigarette smoking. For example, adjustment for triglycerides significantly reduced the odds of disease for PAI activity from 1.41 (95% confidence intervals 1.08, 1.86) to 1.24 (0.93, 1.65) and from 1.47 (1.09, 1.98) to 1.34 (0.99, 1.82) for t-PA antigen. We conclude that impaired fibrinolytic potential (raised PAI activity and t-PA antigen) is associated with peripheral atherosclerosis and that this relationship is partly influenced by lipids and cigarette smoking.

Hemostatic concomitants of syndrome X

The elevated risk factors classically associated with Syndrome X do not adequately explain the increased cardiovascular risk linked to insulin resistance. Considerable indirect evidence and more limited direct evidence suggests that increases in certain prognostically significant hemostatic variables--notably plasma fibrinogen, factor VII coagulant activity, and plasminogen activator inhibitor-1 levels--may be concomitants of Syndrome X. Increased platelet aggregability, and a reduced capacity of vascular endothelium for prostacyclin generation, may also be associated with insulin resistance. Large clinical studies, involving quantification of insulin sensitivity and measurement of hemostatic variables, are required to test this hypothesis. It is unlikely that hyperinsulinemia mediates the connections between insulin resistance and hemostatic variables (or indeed other risk factors in Syndrome X). In light of the remarkably broad impact of insulin resistance on cardiovascular risk factors, promotion of optimal insulin sensitivity should assume a central role in preventive cardiology.

Intraindividual variability of fibrinogen levels and cardiovascular risk profile

Prospective population studies have established that fibrinogen is an independent predictor for ischemic heart disease and stroke. These study conclusions have prompted recommendations that fibrinogen determinations be included in the cardiovascular risk profile. The routine availability of fibrinogen measurements may result in widespread screening prior to establishing the validity of a single fibrinogen level as an accurate descriptor for individual subjects. The objectives of this study were to describe the methodological and intraindividual components of variability in fibrinogen measurements determined by using the Clauss method; to establish the usefulness of a single fibrinogen measurement on risk stratification and retest reproducibility; and to determine the influence of intraindividual fibrinogen variability on sample size estimates. Fibrinogen levels were measured by a modification of the Clauss method. Three cohorts of apparently healthy, nonsmoking volunteers were recruited. The single-day intra-individual component of fibrinogen variability was determined in 39 subjects. For the 5-day intraindividual component of fibrinogen variability, 32 subjects were recruited, and in the 6-week intraindividual study, 28 subjects were included. The coefficient of variation for the methodological component of fibrinogen variability was 5.8% as determined from batch analyses, but the intraindividual coefficient of variation for replicate measures on a single day was 10.7%. The 5-day intraindividual coefficient of variation was 14.2%, and for the 6-week period it was 17.8%. Based on the 6-week data, an average of four fibrinogen measures is required to reduce misclassification error to less than 10%. Sample size estimates were made based on predetermined levels of statistical power and the 6-week intraindividual and interindividual variability estimates.(ABSTRACT TRUNCATED AT 250 WORDS)

Fibrinolysis and thrombosis

In conclusion, venous and arterial thrombi contain significant amounts of fibrin. There is evidence that defective fibrinolytic mechanisms may participate in their genesis or persistence in the body. Some evidence suggests that defective fibrinolysis may presage and predict both arterial and venous thrombi; this is stronger evidence of a causal link with thrombosis. Thrombi protect themselves from lysis by incorporating inhibitors (plasminogen activator inhibitor-1 and alpha 2-antiplasmin) in their structure. Fibrinolytic mechanisms may play a role in the genesis or development of atherosclerotic lesions, in addition to thrombosis. Thrombolytic agents lyse both arterial and venous thrombi when administered shortly after their development. If it proves possible in future to enhance natural fibrinolytic mechanisms and to sustain this enhancement by pharmacological or other means, the interesting prospect of harnessing the fibrinolytic system to prevent thrombus formation, as well as to treat it, will arise.

How does ticlopidine treatment lower plasma fibrinogen?

Many clinical studies have evaluated the clinical efficiency of ticlopidine in vascular pathology and in few of these studies the plasma Fg level was determined as a biological parameter and not a primary end point. All these studies are heterogeneous because plasma Fg concentration have been measured using various methods, patients were included at various time after the acute event and were followed over a period of 1 to 24 months of treatment with ticlopidine, patients suffered from various pathology: peripheral arterial disease, cerebrovascular disease, diabetes or polycythemia vera. Despite the heterogeneity of these prospective studies, a general trend indicates a decrease in the plasma Fg levels by 10 to 25% with ticlopidine compared to placebo. This decrease in circulating Fg was associated with clinical improvement, and, when studied, hemorheological modifications (decreases in whole blood and plasma viscosities). The mechanism of ticlopidine action is discussed.