The PLAT Study: a multidisciplinary study of hemostatic function and conventional risk factors in vascular disease patients

In this paper are reported the basal results of a multidisciplinary, multicenter study designed to explore in a population with ischemic disease the relation between hemostatic variables, conventional risk factors and atherothrombotic sequelae. 953 patients 69 yrs with documented coronary, cerebral or peripheral atherosclerotic disease were studied and followed-up for 24 months. Examinations included hemostatic and lipid laboratory assays, arterial Doppler examination, cerebral computerized tomography and nuclear magnetic resonance, exercise electrocardiogram and coronary angiography. Fibrinogen (301.4 ± 71.52 mg/dl) correlated positively with antithrombin III (r = 0.27) and leukocytes (r = 0.25), negatively with HDL-cholesterol (r = 0.18) and tended to increase with smoking. Heavy smokers had higher leukocyte counts than non-smokers (8.0 ± 2.0 vs. 7.2 ± 2.1 × 103/μl), higher triglycerides (1.87 ± 1.12 vs. 1.53 ± 1.35 mmol/I) and lower HDL-cholesterol (0.93 ± 0.27 vs. 1.00 ± 0.25 mmol/I). FVII correlated positively with triglycerides (r= 0.16) and protein C (r = 0.45). vWF: Ag (145.4 ± 70.58%) ad FVII:C (139.7 ± 59.10%) were positively correlated (r = 0.44). FVIII:C correlated positively with fibrinogen (r = 0.21). Myocardial infarction survivors with associated cerebral and peripheral vascular lesions had higher FVIII:C, FVII, fibrinogen and vWF:Ag. These findings suggest that hemostatic factors may enhance and/or mediate the effects of conventional risk factors in atherothrombotic ischemic events.     

Oral melatonin reduces blood coagulation activity: a placebo-controlled study in healthy young men

Abstract:  Melatonin has previously been suggested to affect hemostatic function but studies on the issue are scant. We hypothesized that, in humans, oral administration of melatonin is associated with decreased plasma levels of procoagulant hemostatic measures compared with placebo medication and that plasma melatonin concentration shows an inverse association with procoagulant measures. Forty-six healthy men (mean age 25 ± 4 yr) were randomized, single-blinded, to either 3 mg of oral melatonin (n = 25) or placebo medication (n = 21). One hour thereafter, levels of melatonin, fibrinogen, and D-dimer as well as activities of coagulation factor VII (FVII:C) and VIII (FVIII:C) were measured in plasma. Multivariate analysis of covariance and regression analysis controlled for age, body mass index, mean arterial blood pressure, heart rate, and norepinephrine plasma level. Subjects on melatonin had significantly lower mean levels of FVIII:C (81%, 95% CI 71–92 versus 103%, 95% CI 90–119; P  = 0.018) and of fibrinogen (1.92 g/L, 95% CI 1.76–2.08 versus 2.26 g/L, 95% CI 2.09–2.43; P  = 0.007) than those on placebo explaining 14 and 17% of the respective variance. In all subjects, increased plasma melatonin concentration independently predicted lower levels of FVIII:C ( P  = 0.037) and fibrinogen ( P  = 0.022) explaining 9 and 11% of the respective variance. Melatonin medication and plasma concentration were not significantly associated with FVII:C and D-dimer levels. A single dose of oral melatonin was associated with lower plasma levels of procoagulant factors 60 min later. There might be a dose–response relationship between the plasma concentration of melatonin and coagulation activity.     

A comparison of FVII:C and FVIIa assays for the monitoring of recombinant factor VIIa treatment

The use of recombinant factor VIIa (rFVIIa) is on the increase, not only to treat haemophilic patients with inhibitors, but also patients with other clotting disorders. However, the most appropriate method of monitoring this treatment remains a question that has yet to be resolved. We studied 24 plasma samples from patients receiving rFVIIa treatment (three had haemophilia A with inhibitors, and three a congenital FVII deficiency) and compared the results obtained from the FVII:C and FVIIa assays. Although a good correlation between the two methods was obtained (r = 0.91), the values of the FVII:C method were 1.63 higher than those of the FVIIa method, with a relatively wide margin in the interval of the FVII:C/FVIIa ratios obtained [95% confidence interval (CI) 1.38--1.88, range 0.68--3.68]. This interval became wider when we compared values of over 6 IU mL(-1), which led us to conclude that the two methods cannot be considered equivalent. As the FVIIa method specifically measures FVIIa, and FVII:C assay is known to have a wide interlaboratory variability, we believe that the FVIIa assay would be more suitable for the monitoring of rFVIIa treatment.     

Plasma levels of factor XIIa and factor VIIa are increased but not related in primary hyperlipidaemia.

The lipolysis of triglyceride-rich lipoproteins may provide a surface that supports the activation of factor XII (FXII) with subsequent activation of factor VII (FVII). Plasma levels of activated FVII (FVIIa) but not activated FXII (FXIIa) are increased in the post-prandial state when there is a transient increase in triglyceride levels. We compared plasma levels of FXIIa antigen in control subjects (n = 33) and in patients with chronically elevated lipids (primary hyperlipidaemia, n = 49), with FVIIa and markers of thrombin generation. Results are given as median (first and third quartiles). Plasma levels of FXIIa [2.34 (1.68-3.32) ng/ml versus 1.53 (0.93-1.86) ng/ml, P = 0.0002], FVIIa [3.02 (2.15-4.64) ng/ml versus 2.20 (1.66-2.56) ng/ml, P = 0.0004], thrombin-antithrombin complexes [3.08 (2.16-5.54) microg/I versus 2.13 (1.46-2.84) microg/l, P = 0.005] and prothrombin fragment 1 + 2 (Pro F1 + 2) [1.28 (1.08-1.50) nmol/l versus 0.92 (0.65-1.08) nmol/l, P = 0.0001] were increased compared with controls irrespective of the type of hyperlipidaemia. In hyperlipdaemic subjects, levels of Pro F1 + 2 were correlated with FVIIa (r = 0.56, P = 0.0002) and FXIIa (r = 0.31, P = 0.03). These results suggest increased activation of both FVII and FXII in hyperlipidaemic subjects, which correlates with increased thrombin generation. Given the lack of correlation between levels of FXIIa and FVIIa, it remains to be established whether the increase in FXIIa is responsible for increased FVIIa activity in this subject group.     

Ankle-brachial index and hemostatic markers in the Atherosclerosis Risk in Communities (ARIC) study cohort

To determine whether elevated levels of hemostatic and inflammatory markers [von Willebrand factor (vWF), fibrinogen, D-dimer, factor VII, factor VIII, PAI-1, tPA, beta-thromboglobulin (beta-TG), CRP, and WBC count] are associated with increased peripheral arterial disease (PAD) prevalence, measured by low ABI, we studied 13,778 participants from the ARIC study in a cross-sectional analysis after adjustment for major cardiovascular risk factors. PAD was positively associated with fibrinogen, vWF, factor VIII, WBC count, D-dimer, beta-TG, and CRP (p for trend <0.05) but not with the other markers. Adjusted odds ratios for the highest versus the lowest quartile of fibrinogen in men and women, respectively, were 3.49 (95% CI 1.68-7.26) and 2.44 (95% CI 1.58-3.77); for vWF 2.36 (95% CI 1.36-4.07) and 1.45 (95% CI 1.00-2.10); for factor VIII 2.31 (95% CI 1.36-3.94) and 1.68 (95% CI 1.14-2.48). In a smaller subset, the sex and risk factor adjusted odds ratio for the highest versus the lowest quartile of D-dimer was 2.70 (95% CI 1.56-4.65), for beta-TG was 1.80 (95% CI 1.12-2.88), and for CRP was 1.57 (95% CI 0.84-2.95). Plasma levels of hemostatic and inflammatory markers are elevated in PAD, suggesting these processes are involved in the pathophysiology of PAD.     

Lipid-lowering therapy corrects endothelial cell dysfunction in a short time but does not affect hypercoagulable state even after long-term use in hyperlipidemic patients.

Lipid-lowering therapy reduces cardiac events to an extent that is disproportionate to the small degree of regression of coronary atherosclerosis observed among hyperlipidemic patients. We prospectively investigated the effects of lipid reduction using simvastatin on the endothelial dysfunction and hypercoagulability found in hyperlipidemic patients. We measured levels of coagulation factors [factor VII (FVII) coagulant activity (FVIIc), FVII antigen (FVIIAg), activated FVII (FVIIa), and fibrinogen], and markers of coagulation activation [prothrombin fragment 1 + 2 (F1 + 2)] and endothelial cell dysfunction [von Willebrand factor (vWF)] in 20 hyperlipidemic patients, 20 hypertensive patients, and 20 normotensive normolipidemic controls. The levels of FVIIa, FVIIc, FVIIAg, F1 + 2, and vWF were all higher in hyperlipidemic patients, but only FVIIa, F1 + 2, and vWF levels were higher in hypertensive patients than in controls. We measured the above parameters in 13 hyperlipidemic patients before and after 1, 3, 6, 12 and 24 months of simvastatin therapy and compared these values with those in 15 hypertensive patients at baseline and after 12 and 24 months. The median (25th-75th percentile) level of total cholesterol was decreased from 259 (255-278) to 206 (176-220) mg/dl after 1 month of simvastatin therapy and this reduction persisted for 2 years. The plasma level of vWF [136% (113-158%)] was not changed after 1 month of administration of simvastatin [132% (115-153%)], but was decreased after 3 months of treatment [114% (96-128%), P<0.01]. This decrease also persisted for 2 years during simvastatin therapy and both of these reductions were significant, compared with levels in hypertensive patients. In contrast, levels of fibrinogen, FVIIc, FVIIAg, FVIIa, and F1 + 2 did not change throughout the 2 years of simvastatin therapy. We conclude that lipid reduction using simvastatin corrects endothelial cell dysfunction but not hypercoagulability in hyperlipidemic patients. The improvement in endothelial cell function brought about by lipid-lowering therapy might contribute to the reduction in cardiac events within a relatively short time period in hyperlipidemic patients.     

Social determinants of von willebrand factor: the Whitehall II study

Data from the Whitehall II Study and others have demonstrated a role for the metabolic syndrome and fibrinogen underlying the association between social position and coronary heart disease. In this study, we examined the role of an additional hemostatic factor and marker of endothelial dysfunction, von Willebrand factor (vWF). Four thousand five hundred and forty-eight men and 1837 women were examined in the third phase of the study, which took place between 1991 and 1993. Employment grade was used as a measure of socioeconomic position. An inverse relation between employment grade and vWF was evident (P<0.0003). This employment grade gradient was apparent overall, and the relation persisted even when nonsmokers and participants with poor health were removed from the analyses (P=0.02). The difference between the highest (unified grades 1 to 6) and lowest (clerical/support) employment grades in vWF concentrations was 8.9 IU/dL (95% CI 6.0, 11.8; P<0.001) for men and 6.9 IU/dL (95% CI 4.0, 9.7; P=0.06) for women. vWF was associated with a number of biological factors that themselves showed an employment grade gradient, including fibrinogen (P<0.001), fasting and postload glucose (P<0.05) levels, and fasting and postload insulin (P<0.01) levels. Associations with smoking and alcohol intake were apparent. Smoking showed a threshold effect, such that only men who smoked >21 cigarettes per day produced a significantly increased vWF level (P<0.05) compared with lighter smokers. The health-related behaviors explained 25% of the grade gradient in men and 28% in women, while the biological factors accounted for 32% in men and 22% in women. We conclude that there is a grade gradient in vWF that was not fully explained by health-related behaviors and risk factors for coronary heart disease. These data are consistent with the hypothesis that endothelial dysfunction is part of the explanation for social inequalities in cardiovascular disease.     

In vitro effects of heparin and tissue factor pathway inhibitor on factor VII assays. possible implications for measurements in vivo after heparin therapy.

The coagulant activity of blood coagulation factor VII (FVII:C) can be lowered by changes in lifestyle and by therapeutic intervention, e.g. heparin infusion. The question is, however, whether FVII:C determined ex vivo is a valid measure of the FVII activity in vivo. We measured plasma FVII:C, activated FVII (FVIIa), FVII protein (FVII:Ag), tissue factor pathway inhibitor (TFPI), triglycerides, and free fatty acids (FFA) before and 15 min after infusion of a bolus of unfractionated heparin (50 IU/kg body weight) in 12 healthy subjects. Additionally, we conducted in vitro experiments to investigate the effect of unfractionated heparin and TFPI, which is released from the endothelium by heparin, on FVII:C, FVIIa, and FVII:Ag. Heparin infusion decreased triglycerides and increased FFA and TFPI. This was accompanied by significant reductions in FVIIa, FVII:C and FVII:Ag. In vitro, anti-TFPI antibodies increased FVIIa and FVII:C, and heparin reduced FVIIa. The heparinase Hepzyme was unable to abolish the effect of heparin. There were no in vitro effects on FVII:Ag. We conclude that, due to interference by TFPI and heparin in post-heparin plasma, it is impossible to measure the in vivo FVII activity by means of FVII clotting assays. These assays should therefore not be used to measure the coagulation status of patients in heparin therapy, unless extraordinary precautions are taken to eliminate TFPI and heparin effects ex vivo. The observed effect of heparin on FVII:Ag should be investigated further.     

Inhibition of factor VIIa generation and prothrombin activation by treatment with enoxaparin in patients with unstable angina

Factor VIIa (FVIIa) and thrombin generation occur in patients suffering an acute coronary event. We studied the effect of treatment with enoxaparin on FVIIa and prothrombin activation in patients with unstable angina. Anti-Xa activity, FVIIa, FVII coagulant activity (FVII:C) and FVII antigen (FVII:Ag), free tissue factor pathway inhibitor (TFPI), and prothrombin fragments 1 + 2 (F1+2) were measured in patients' plasma, over a 24-h treatment period with enoxaparin. All 14 patients recruited in the study (mean age 68 years) were treated with a subcutaneous injection of enoxaparin, 1 mg/kg twice daily. Blood was drawn just before, and at different time intervals after, the first injection. Before enoxaparin administration, the levels of FVIIa (4.02 +/- 0.8 ng/ml) and F1+2 (2.68 +/- 0.2 nmol/l) were significantly increased as compared with control subjects (2.3 +/- 0.3 ng/ml and 0.9 +/- 0.1 nmol/l respectively, P < 0.05). Free TFPI, FVII:C and FVII:Ag were within normal ranges. One hour after the first injection of enoxaparin, FVIIa and F1+2 levels decreased by 65% and 50%, respectively, and no significant fluctuations were noted throughout the observation period. The concentrations of FVII:C and FVII:Ag were not modified as compared with baseline values. After each injection, the peak concentrations of free TFPI and anti-Xa activity were observed at 2 and 4 h respectively. The kinetics of FVIIa and F1+2 inhibition did not follow those of anti-Xa activity and TFPI release.     

Insulin resistance is accompanied by increased von Willebrand factor levels in nondiabetic women: a study of offspring of type 2 diabetic subjects compared to offspring of nondiabetic subjects

OBJECTIVES: To examine whether levels of von Willebrand factor (vWF), fibrinogen and fibronectin are related to a parental history of type 2 diabetes and to determine possible explanatory factors for high versus low vWF and fibrinogen. DESIGN: Cross-sectional study. SUBJECTS, MAIN OUTCOME MEASURES: We compared vWF, fibrinogen and fibronectin in 88 nondiabetic offspring of type 2 diabetic subjects (relatives) and 103 offspring of nondiabetic subjects (controls). Other measurements included urinary albumin excretion rate, blood pressure, lipid profile and insulin resistance using homeostasis model assessment (HOMAIR). RESULTS: There were no significant differences in vWF (1.12 vs. 1.06 IU x mL(-1), P = 0.296), fibrinogen (3.2 vs. 3.1 g x L(-1); P = 0.263) or fibronectin (0.39 vs. 0.40 g x L(-1), P = 0.448) between relatives and controls. With multiple logistic regression we determined explanatory factors for high versus low vWF and fibrinogen. Age (P < 0.01), urinary albumin excretion rate (P < 0.05), ischaemic heart disease (IHD) (P < 0.05) were found to be significant explanatory factors for vWF above the median (1.10 IU x mL(-1)). Interaction between insulin resistance and sex was found. Odds ratio for high versus low insulin resistance was 18.39 (P < 0.001) for women and 1.92 (P = 0.32) for men. Body mass index (BMI) (P < 0.05), sex (P < 0.01), smoking status (P < 0.05) and IHD (P < 0.01) were significant explanatory factors for fibrinogen above the median (3.1 g x L(-1)). CONCLUSIONS: Levels of vWF, fibrinogen and fibronectin were not influenced by a parental history of type 2 diabetes. Insulin resistance was found to be a significant risk indicator for high vWF only in women. This may indicate that insulin resistance is a higher risk factor for women than for men, when the outcome is endothelial dysfunction possibly resulting in overt cardiovascular disease.     

R353Q polymorphism, activated factor VII, and risk of premature myocardial infarction in Japanese men.

BACKGROUND: The association between myocardial infarction (MI) and the R353Q polymorphism of the Factor VII (FVII) gene, which reportedly influences FVII concentrations, activated Factor VII (FVIIa), or FVII antigen (FVIIag), remains controversial. METHODS AND RESULTS: The present case - control study in 127 Japanese men with their first MI at or before 45 years of age and 150 matched healthy controls was designed to clarify this association in premature MI. R353Q polymorphism was determined by polymerase chain reaction, and plasma concentrations of FVIIa and FVIIag were assayed. The distribution of the RR, RQ, and QQ genotypes with respect to R353Q polymorphism was 117, 10, and 0 in the patients, and 131, 17, and 2 in the controls. The Q allele was negatively associated with premature MI (odds ratio =0.41, p=0.038). The plasma concentration of FVIIa was slightly higher in patients (55.1+/-40.9 U/L) than in controls (44.8+/-20.2 U/L), but not significantly (p=0.078); the plasma concentration of FVIIag did not differ between patients (88.7+/-15.7%) and controls (87.0+/-9.0%) (p=0.557). Plasma FVIIa concentrations were influenced by R353Q polymorphism (p<0.001). CONCLUSIONS: The Q allele may be protective against premature MI.     

Dietary factor VII activation does not increase plasma concentrations of prothrombin fragment 1+2 in patients with stable angina pectoris and coronary atherosclerosis

Studies in healthy subjects showed that blood coagulation factor VII (FVII) is activated postprandially after consumption of high-fat meals, but accompanying thrombin formation has not been demonstrated. In patients with coronary atherosclerosis, the arterial intima is supposed to present more tissue factor, the cofactor of FVII, to circulating blood; therefore, thrombin formation in response to FVII activation is more likely to occur in such patients. This hypothesis was tested in a randomized crossover study of 30 patients (aged 43 to 70 years) with stable angina pectoris and angiographically verified coronary atherosclerosis. They were served a low-fat (5% of energy from fat) breakfast and lunch and a high-fat (40% of energy from fat) breakfast and lunch on 2 different days. Venous blood samples were collected at 8:15 AM (fasting), 12:30 PM, 2:00 PM, 3:30 PM, and 4:45 PM and analyzed for triglycerides, activated FVII (FVIIa), FVII protein concentration (FVII:Ag), prothrombin fragment 1+2 (F1+2), and soluble fibrin. Triglyceride levels increased from fasting levels on both diets, but they increased most markedly on the high-fat diet. FVIIa and FVIIa/FVII:Ag increased with the high-fat diet and decreased with the low-fat diet. For both diets, FVII:Ag and F1+2 decreased slightly. No postprandial changes were observed for soluble fibrin. Postprandial mean values of triglycerides, FVIIa, FVII:Ag, and FVIIa/FVII:Ag were significantly higher for the high-fat diet than for the low-fat diet. Our findings confirm that high-fat meals cause immediate activation of FVII. The clinical implication is debatable because FVII activation was not accompanied by an increase in plasma F1+2 concentrations in patients with severe atherosclerosis. However, a local thrombin generation on the plaque surface cannot be excluded.     

Function of von Willebrand factor in children with diarrhea-associated hemolytic-uremic syndrome (D+ HUS).

Reports on von Willebrand factor (vWF) in hemolytic-uremic syndrome (HUS) are not unequivocal. Because of potential pathogenic implications, we examined the ability of vWF to bind to collagen in vitro, which reflects its function. Plasma vWF antigen (vWF:Ag) and collagen-binding activity (vWF:CBA) were measured by enzyme-linked immunosorbent assay in children with (1) diarrhea-associated (D+) HUS (n = 27), (2) chronic renal insufficiency (CRI) (n = 8), (3) gastroenteritis (GE) not associated with HUS (n = 15), (4) immune thrombocytopenia (ITP) (n = 40) and from controls (n = 35). Structural vWF was evaluated by multimer analysis. Children with D+ HUS had vWF:Ag of 2.53 and vWF:CBA of 1.98 U/mL. The corresponding values for patients with ITP were 1.35 and 1.82 U/mL, with CRI 1.55 and 1.55 U/mL, and with GE 1.68 and 2.10 U/mL; all values were higher than in controls (1.04 and 1.16 U/mL). The mean ratio of vWF:CBA to vWF:Ag ratio in controls was 1.13; only children with HUS had a dysfunctional vWF, as indicated by a low ratio of 0.78; the ratio was elevated in children with ITP (1.36) and GE (1.27) and was normal in those with CRI (1.06). No ultralarge molecular multimers of vWF were detected in any group, including HUS. The very high concentration of plasma vWF:Ag in HUS probably reflects endothelial cell damage or irritation. In contrast to all other groups, only children with HUS had a dysfunctional vWF, caused either by a primary (due to enterohemorrhagic Escherichia coli) or secondary (due to consumption of functionally active vWF) process. This abnormality was not obvious as structural anomaly by multimer analysis.     

Comparison of coagulant activity of factor VII and activated factor VII activity assays when used for determination of recombinant activated factor VII levels in plasma.

Two assays [coagulant activity of factor VII (FVII:C) and activated factor VII (FVIIa) activity] are currently available for the assessment of factor VII and FVIIa pharmacokinetics. This article presents the results of a comparison of the two assays when applied both in vitro as well as during clinical pharmacokinetic trials of recombinant FVIIa (rFVIIa) administered to healthy individuals and haemophilia patients. The in-vitro data showed that, for the FVII:C assay, plasma samples do not dilute in parallel. For the FVIIa activity assay, dilutions of samples are both parallel and linear with different dilutions of the calibrator. Moreover, intra-assay variation was found to be smaller for the FVIIa activity assay than for the FVII:C assay. When adding different amounts of rFVIIa (0-6 microg/ml) to normal plasma, a mean specific activity of rFVIIa of 48.6 U/mug was observed on applying the FVII:C assay; however, the specific activity decreased with increasing levels of rFVIIa. For the FVIIa activity assay, the mean specific activity was 45.4 IU/mug. Direct comparison of the two activity assays showed that no simple conversion between FVII:C and FVIIa activity measurements are possible. When applying the two assays for pharmacokinetic assessments in two clinical trials, statistically significant different estimates for the area under the curve, half-life, clearance and volume of distribution were obtained. In conclusion, for evaluation of rFVIIa pharmacokinetic properties, activity should be measured with the FVIIa activity assay - which is a more specific and reliable assay of the two available factor VII activity assays, especially when assessing low activity levels.     

Increased thrombin-activatable fibrinolysis inhibitor and decreased tissue factor pathway inhibitor in patients with hypothyroidism

Various abnormalities of coagulation–fibrinolytic system have been reported in patients with thyroid dysfunction. Several studies indicate that coagulation and fibrinolytic system is disturbed in the patients with hypothyroidism. Also, the influence of hypothyroidism on hemostasis is controversial; both hypocoagulable and hypercoagulable states have been reported. The levels of plasma thrombin-activatable fibrinolysis inhibitor (TAFI) antigen and tissue factor pathway inhibitor (TFPI) have been investigated only once in patients with hypothyroidism. Therefore, the main purpose of this study was to evaluate the profile of coagulation and fibrinolytic parameters including TAFI and TFPI in patients with hypothyroidism. Fifteen patients with untreated hypothyroidism and 15 age-matched healthy controls were included in the study. Factors V(FV), VII (FVII), VIII (FVIII) activities, von Willebrand factor (vWF), protein C, protein S, thrombomodulin (TM), TFPI, and TAFI were measured. The relationships between serum thyroid hormones and these hemostatic parameters were examined. Compared with the control subjects, FVII activity, and TM Ag and TAFI Ag levels were significantly increased in patients with hypothyroidism, whereas FV, FVIII, vWF, protein C and protein S activities, and TFPI Ag levels were significantly decreased. We did not find any significant correlation between serum thyroid hormones and the hemostatic parameters that we measured. In conclusion, we found some important differences in the hemostatic parameters between the patients with hypothyroidism and healthy controls. Increased FVII, TM, and TAFI and decreased FV, FVIII, vWF, protein C, protein S, and TFPI in these patients represent a potential hypercoagulable and hypofibrinolytic state, possible endothelial dysfunction, which might augment the risk for atherosclerotic and atherothrombotic complications. Thus, disturbances of the hemostatic system may contribute to the excess mortality due to cardiovascular disease seen in patients with hypothyroidism.     

Administration of granulocyte-colony-stimulating factor for allogeneic hematopoietic cell collection may induce the tissue factor-dependent pathway in healthy donors

The hypercoagulable state caused by the use of recombinant human granulocyte colony-stimulating factor (rhG-CSF) has been cited in anecdotal reports. Since tissue factor (TF) is the main initiator of the coagulation cascade, we examined if rhG-CSF had an inductive effect on the TF-dependent pathway in 18 healthy donors receiving rhG-CSF (10 microg/kg/day x 5 days) for peripheral blood progenitor cell mobilization. After rhG-CSF, there were increases both in TF antigen (TF:Ag) (P=0.01) and TF procoagulant activity (TF:PCA) (P=0.06) plasma levels and in TF:Ag cytofluorimetric expression on CD33 (+) cells (P=0.04). Mean activities of FVIII and vWF also increased significantly. Thrombin time was slightly prolonged (P=0.06) due to significant increases in plasma D-dimer levels. In addition, while FIX activity remained stable, there were marked reductions in mean plasma FX and FII activities and a slight decrease in FVII activity that resulted in a significant prolongation of prothrombin time within normal ranges. In conclusion, the administration of rhG-CSF led to a "prothrombotic state" via stimulation of TF and increased endothelial markers, such as F VIII and vWF. In the light of these findings, the use of rhG-CSF for stem cell mobilization should be undertaken cautiously in healthy donors with underlying thrombotic risk factors.     

冠心病患者血浆组织因子活性及凝血因子VII水平改变

目的研究汉族冠心病患者血浆中组织因子活性（aTF）、活化凝血因子VII（FVIIa）和凝血因子VII抗原（FVII:Ag）水平并探讨其与冠脉病变支数之间的关系。方法aTF采用发色底物法,FVIIa和FVII:Ag采用ELISA法。结果与对照组相比,冠心病患者血浆中aTF（P<0.05）、FVIIa（P<0.01）及FVII:Ag（P<0.05）水平均显著升高;急性冠状动脉综合征（ACS）患者中aTF高于稳定型心绞痛（SAP）组（P<0.05）和对照组（P<0.01）,后两者之间无显著差异;ACS和SAP患者之间血浆中FVIIa水平无显著差异,但均高于对照组;ACS组中FVII:Ag水平明显高于对照组。在不同冠脉病变支数的患者之间,aTF、FVIIa及FVII:Ag水平没有差异。结论SAP和ACS患者均可出现外源性凝血途径的激活,血浆中aTF增强可能预示了急性冠脉事件的发生;FVIIa可能可以作为冠心病的早期分子标志物;冠脉病变支数可能不能反映凝血激活的程度。     

Elevated fibrinogen levels and subsequent subclinical atherosclerosis: the CARDIA Study

ObjectiveTo determine whether elevated levels of hemostatic factors are associated with the subsequent development of subclinical cardiovascular disease.MethodsFibrinogen, factors VII (FVII) and VIII (FVIII), and von Willebrand factor (vWF) were measured in 1396 participants in the Coronary Artery Risk Development in Young Adults (CARDIA) study. Coronary artery calcification (CAC) and carotid intimal/medial thickness (CIMT) were determined 13 years later. The adjusted prevalence of CAC and mean CIMT across the quartiles of each hemostatic factor was computed for the total sample and for each race and gender group.ResultsThe age-, race-, and gender-adjusted prevalences of CAC with increasing quartiles of fibrinogen were 14.4%, 15.2%, 20.0%, and 29.1% (p < 0.001 for trend). This trend persisted after further adjustment for body mass index (BMI), smoking, educational level, center, systolic blood pressure (BP), diabetes, antihypertensive medication use, total and high-density lipoprotein (HDL) cholesterol, and CRP. A similar trend was observed for CIMT (age-, race- and gender-adjusted, p < 0.001; multivariable-adjusted, p = 0.014). Further analyses of race and gender subgroups showed that increasing quartiles of fibrinogen were associated with CAC and CIMT in all subgroups except black men. The prevalence of CAC was not associated with increasing quartiles of FVII, FVIII, or vWF, suggesting they may be less involved in plaque progression.ConclusionAn elevated fibrinogen concentration in persons aged 25–37 is independently associated with subclinical cardiovascular disease in the subsequent decade.     

Increased markers of thrombogenesis in chronic atrial fibrillation: effects of warfarin treatment.

OBJECTIVE--To determine whether chronic atrial fibrillation is associated with abnormalities in plasma fibrinogen, von Willebrand factor (vWF) (a marker of endothelial disturbance), or fibrin D- dimer (a measure of fibrin turnover); and if so, whether such levels are related to haemodynamic disturbance (enlarged left atrium, poor left ventricular function) or existing treatment with warfarin or aspirin. To investigate the effects of introducing warfarin in patients with atrial fibrillation on fibrinogen and D- dimer levels. DESIGN--Cross sectional population sample controlled study and longitudinal study of patients undergoing anticoagulation. SETTING--District general hospital. SUBJECTS--87 patients (44 men and 43 women of mean (SEM) age 63.0 (1.0)) with chronic atrial fibrillation. At the time of the study, 37 were taking no antithrombotic medication (group 1), 31 were taking warfarin (including two on warfarin and aspirin) (group 2) and 19 were taking aspirin alone (group 3). They were compared with 158 population controls from a random population sample (the second Glasgow monitoring trends and determinants in cardiovascular disease study). As part of clinical treatment warfarin was introduced in 20 patients with chronic atrial fibrillation (14 men and six women of mean (SEM) (range) age 63.9 (2.35 (32-74) years). RESULTS--Plasma fibrinogen remained significantly increased in patients of group 1 (no antithrombotic medication) compared with that of the population controls (median difference 1.23 g/l; 95% confidence interval (CI) 0.88 to 1.62, P < 0.0001). There was also a significant increase in plasma D-dimer levels (median difference 77 ng/ml; 95% CI 38 to 122, P < 0.01) and vWF (median difference 63 IU/dl; 95% CI 38 to 89, P < 0.0001). There was no significant difference in plasma fibrinogen (median difference 0.14 g/l; 95% CI -0.44 to 0.77, P = 0.65) or vWF (median difference 3.5 IU/dl; 95% CI - 41 to 41, P = not significant in patients of group 2 (warfarin treatment) compared with that of patients in group 1. Levels of D-dimer were significantly lower in group 2 (median difference 90 ng/ml, 95% CI 39 to 150, P < 0.0001) than in group 1. There were no significant differences in plasma fibrinogen (median difference 0.08 g/l; 95% CI - 0.52 to 0.77, P = 0.73), D-dimer (median difference - 34 ng/ml; 95% CI - 114 to 21.0, P = 0.25), or vWF (median difference 2%; 95% CI - 35 to 41, P = not significant) levels between patients of groups 1 and 3. There were no significant correlations between the coagulation indices and left atrial volume or ventricular function. There was a significant positive correlation between plasma fibrin D-dimer and vWF levels in patients of groups 1 and 3 (r = 0.52, P < 0.001). There was a significant reduction in median plasma fibrin D-dimer levels at 2 months after the introduction of warfarin (181 ng/ml v 80 ng/ml, P < 0.001), but no effect on plasma fibrinogen. CONCLUSIONS--Increased median plasma fibrinogen and vWF levels were found in patients with chronic atrial fibrillation. Plasma D-dimer levels were also increased in patients with chronic atrial fibrillation not receiving warfarin, suggesting increased intravascular thrombogenesis in such patients. Introduction of warfarin normalised circulating fibrin D- dimer levels, suggesting that warfarin treatment was effective in preventing excessive fibrin turnover, consistent with the antithrombotic effects of warfarin. These results suggest three possible thrombotic markers to assess patients with atrial fibrillation who are at high risk of thrombogenesis; D-dimer also merits assessment as a measure of reduction in thrombotic risk in patients receiving warfarin.