Interrelationship of plasma triglyceride and coagulant factor VII levels in normotriglyceridemic hypercholesterolemia

The vulnerable blood. Coagulation and clot structure in diabetes mellitus

Patients with diabetes are at increased risk of cardiovascular morbidity and mortality. While arteriosclerotic lesions have long been recognized as the underlying cause more recent studies suggest that alterations of the blood are also critically involved. Following plaque rupture, adherence of platelets is followed by the formation of a cross-linked fibrin clot. Patients with diabetes exhibit a prothrombotic milieu consisting of hyper reactive platelets, a tight and rigid clot structure which is due to up-regulation of coagulation factors and prolongation of clot lysis. Metabolic alterations as well as inflammatory processes, which are up-regulated in diabetes, are thought to be the main underlying causes. More recently, the complement cascade has emerged as a potential new player in this context with several complement components directly influencing both platelet function and coagulation. This review provides an overview concerning the changes that lead to alterations of platelet function and clot structure in diabetes.

Association of lifestyle-related factors with circadian onset patterns of acute myocardial infarction: a prospective observational study in Japan

OBJECTIVE

The onset of acute myocardial infarction (AMI) shows characteristic circadian variations involving a definite morning peak and a less-defined night-time peak. However, the factors influencing the circadian patterns of AMI onset and their influence on morning and night-time peaks have not been fully elucidated.

DESIGN, SETTING AND PARTICIPANTS

An analysis of patients registered between 1998 and 2008 in the Osaka Acute Coronary Insufficiency Study, which is a prospective, multicentre observational study of patients with AMI in the Osaka region of Japan. The present study included 7755 consecutive patients with a known time of AMI onset.

MAIN OUTCOMES AND MEASURES

A mixture of two von Mises distributions was used to examine whether a circadian pattern of AMI had uniform, unimodal or bimodal distribution, and the likelihood ratio test was then used to select the best circadian pattern among them. The hierarchical likelihood ratio test was used to identify factors affecting the circadian patterns of AMI onset. The Kaplan-Meier method was used to estimate survival curves of 1-year mortality according to AMI onset time.

RESULTS

The overall population had a bimodal circadian pattern of AMI onset characterised by a high and sharp morning peak and a lower and less-defined night-time peak (bimodal p<0.001). Although several lifestyle-related factors had a statistically significant association with the circadian patterns of AMI onset, serum triglyceride levels had the most prominent association with the circadian patterns of AMI onset. Patients with triglyceride ≥150 mg/dL on admission had only one morning peak in the circadian pattern of AMI onset during weekdays, with no peaks detected on weekends, whereas all other subgroups had two peaks throughout the week.

CONCLUSIONS

The circadian pattern of AMI onset was characterised by bimodality. Notably, several lifestyle-related factors, particularly serum triglyceride levels, had a strong relation with the circadian pattern of AMI onset.

TRIAL REGISTRATION NUMBER

UMIN000004575.

Inflammation and thrombosis in diabetes

Patients with diabetes mellitus are at increased risk of cardiovascular morbidity and mortality. Atherothrombosis, defined as atherosclerotic lesion disruption with superimposed thrombus formation, is the most common cause of death among these patients. Following plaque rupture, adherence of platelets is followed by local activation of coagulation, the formation of a cross-linked fibrin clot and the development of an occlusive platelet rich fibrin mesh. Patients with diabetes exhibit a thrombotic risk clustering which is composed of hyper-reactive platelets, up regulation of pro-thrombotic markers and suppression of fibrinolysis. These changes are mainly mediated by the presence of insulin resistance and dysglycaemia and an increased inflammatory state which directly affects platelet function, coagulation factors and clot structure. This prothrombotic state is related to increased cardiovascular risk and may account for the reduced response to antithrombotic therapeutic approaches, underpinning the need for adequate antithrombotic therapy in patients with diabetes to reduce their cardiovascular mortality.

Caloric restriction alone and with exercise improves CVD risk in healthy non-obese individuals

Calorie restriction (CR) delays the development of age-associated disease and increases lifespan in rodents, but the effects in humans remain uncertain.

PURPOSE

Determine the effect of 6 months of CR with or without exercise on cardiovascular disease (CVD) risk factors and estimated 10-year CVD risk in healthy non-obese men and women.

METHODS

Thirty-six individuals were randomized to one of three groups for 6 months: Control, 100% of energy requirements; CR, 25% calorie restriction; CR+EX, 12.5% CR+12.5% increase in energy expenditure via aerobic exercise. CVD risk factors were assessed at baseline, 3 and 6 months.

RESULTS

After 6 months, CR and CR+EX lost approximately 10% of body weight. CR significantly reduced triacylglycerol (-31+/-15mg/dL) and factor VIIc (-10.7+/-2.3%). Similarly CR+EX reduced triacylglycerol (-22+/-8mg/dL) and additionally reduced LDL-C (-16.0+/-5.1mg/dL) and DBP (-4.0+/-2.1mmHg). In contrast, both triacylglycerol (24+/-14mg/dL) and factor VIIc (7.9+/-2.3%) were increased in the Control group. HDL-cholesterol was increased in all groups while hsCRP was lower in the Controls versus CR+EX. Estimated 10-year CVD risk significantly declined from baseline by 29% in CR (P<0.001) and 38% in the CR+EX (P<0.001) while remaining unchanged in the Control group.

CONCLUSIONS

Based on combined favorable changes in lipid and blood pressure, caloric restriction with or without exercise that induces weight loss favorably reduces risk for CVD even in already healthy non-obese individuals.

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.

Dietary fatty acids, hemostasis, and cardiovascular disease risk

The cause of many myocardial infarctions is occlusive thrombosis, or a blood clot that stops blood flow in a coronary artery. Hemostasis involves a complex system of factors, which normally form and degrade blood clots, that work within a delicate balance. Emerging evidence suggests that some hemostatic factors, including factor VII, fibrinogen, and plasminogen activator inhibitor-1, are associated with increased risk for cardiovascular disease (CVD). Accumulating evidence suggests a relationship between dietary fatty acids and emerging hemostatic CVD risk factors, although much of this evidence is incomplete or conflicting. Dietary supplementation with marine n-3 fatty acids prolongs bleeding time and may decrease risk for thrombosis. Factor VII coagulant activity modestly decreases with reductions in saturated fatty acid (SFA) intake and thereby may contribute to the beneficial effects of low SFA diets. Large triglyceride-rich particles formed during postprandial lipemia can support the assembly and function of coagulation complexes and seem to play a role in the activation of factor VII, and thus may partially explain increased CVD risk associated with increased postprandial triglyceridemia. As our understanding of the role of dietary fatty acids and hemostasis evolves, it is likely that we will be able to make specific dietary recommendations to further decrease CVD risk. At this juncture, however, increasing marine n-3 fatty acids and decreasing certain SFAs are leading strategies to reduce hemostatic CVD risk factors. An array of dietary strategies that target multiple CVD risk factors could have a greater impact on CVD than a single risk factor intervention strategy.

Vitamin K-dependent and vitamin K-independent hypocoagulant effects of dietary fish oil in rats

In rats, dietary fish oil causes a plasma triglyceride-lowering as well as hypocoagulant effect. The latter is apparent from reduced levels of vitamin K-dependent coagulation factors and a decreased thrombin-forming potential of the coagulating plasma. Here, we describe that intervention with low levels of n-3 polyunsaturated fatty acids (n-3 PUFAs, about 2.5% of digestible energy, en%) resulted in no more than a small reduction in coagulation factors, when supplied as part of a high-fat diet relatively rich in vitamin K. Plasma triglycerides also remained unchanged. On the other hand, when feeding rats with low- or high-fat diets restricted in vitamin K, intervention with 3 en% of n-3 PUFAs acids (fish oil) caused only a lowering in triglycerides in combination with high fat. The fish caused a reduction in coagulation potential and levels vitamin K-dependent coagulation factors (prothrombin and factor VII) that was most prominent with the low-fat diet. Fish oil, in combination with low fat but not with high fat, reduced the vitamin K levels in the liver of the animals. In addition, regardless of the fat content, the vitamin K-independent coagulation factor V was decreased in the fish oil groups. Taken together, these results indicate that, in the rat, the hypocoagulant effect of a low dose of n-3 PUFAs is most apparent at low intakes of both vitamin K and fat, is not linked to the triglyceride plasma level, but involves modulation of both vitamin K-dependent and -independent coagulation factors.

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.

Diet and hemostatic factors

The coagulation, fibrinolytic, and platelet activating systems are complex and interact extensively, and with other systems such as inflammation. Key reactions often require biomembranes, suggesting that dietary lipids, to the extent that they influence membrane composition, may have important regulatory roles. Also, recent evidence suggests that both postprandial and fasting lipoproteins may be associated with either factor levels or activation state or both. This issue has added importance because several hemostatic and fibrinolytic factors are known CVD risk factors. Although there are associations between fasting lipid levels and several coagulation and fibrinolytic factors, the mechanisms are unclear, as are the implications for intervention. In general, postprandial lipids are at least somewhat procoagulant because they activate factor VII. It remains to be demonstrated, however, that this postprandial activation has important clinical correlates. Dietary supplementation with marine omega-3 fatty acids does prolong the bleeding time and may decrease thrombotic potential; however, other than this, little is known about the direct effects of dietary fatty acids on hemostatic and fibrinolytic activities. Much work is needed in carefully controlled studies to expand our knowledge in this important area.

Interaction of physical activity and diet: implications for haemostatic factors

Regular moderate intensity physical activity and habitual diet providing no more than one third of energy from fats have been recommended for the prevention of atherosclerotic diseases. The background for these guidelines is the key role of plasma lipids. However, the importance of thrombogenesis in acute myocardial infarction has become obvious during the last decade. Hyperlipidaemia and excess of adipose tissue increase platelet aggregability and blood coagulation, and decrease fibrinolysis. Both regular physical activity and dietary fat reduction decrease blood lipids and body fat thereby diminishing the risk of thrombosis. Currently, data on interactions between physical activity and diet on haemostasis are scarce, and the few studies available have not demonstrated additional effects when these two lifestyle modifications have been combined. This paper is restricted only to studies using controlled randomized design. Regular moderate intensity physical activity as well as diet rich in omega-3 fatty acids decrease platelet aggregability. The effects of regular physical activity on plasma fibrinogen remain contradictory, while the impact of diet is even less clear. Plasminogen activator inhibitor-1, a possible link between insulin resistance syndrome and coronary heart disease, may decrease due to physical training or low fat diet. It can be hypothesized that moderation in physical activity and diet carries a more powerful impact on blood coagulation and fibrinolysis than either lifestyle modification alone. Studies focusing on the interactions of regular moderate physical activity and fat-modified diet are needed in efforts to optimize the preventive actions by lifestyle changes.

Oral contraceptives highlight the genotype-specific association between serum phospholipids and activated factor VII

The present analysis was undertaken to study the effect of oral contraceptive (OC) use on activated factor VII (FVIIa) in subjects characterized by FVII genotypes, with the further aim of evaluating the role of lipids in this pharmacological interaction. In OC users (n=42) and nonusers (n=130) of comparable age, we examined the FVII phenotypic variables (FVII coagulant activity [FVIIc], FVII antigen, and FVIIa), FVII genotypes (the 353R/Q and 5'F7 polymorphisms analyzed in combination; alleles M1/M2 and A1/A2, respectively), and a number of lipid and lipoprotein parameters: serum concentrations of total cholesterol (chol), low density lipoprotein and high density lipoprotein-chol, triglycerides, phospholipids (PhLs), apolipoprotein A1, and lipoprotein(a). PhLs, triglycerides, apolipoprotein A1, chol, FVII antigen, FVIIc, and high density lipoprotein-chol levels were shown to be statistically higher in users than nonusers. FVII levels, particularly those of FVIIa and FVIIc, were much higher in homozygotes for the A1 and M1 alleles (A11 M11), especially in OC users. A strong association was found between PhL and FVIIa: in the multiple regression analysis, women taking OCs who had elevated PhL concentrations also had very high levels of FVIIa, but only if their genotype was A11 M11. These results indicate that the increased FVII levels in OC users depend on the FVII genotype and that high PhL concentrations predict very high levels of FVIIa and FVIIc.

Association of factor VII protein concentration with lifestyle factors

Several studies have demonstrated that changes in fasting levels of factor VII coagulant activity (FVII:C), a thrombotic risk marker, are due to changes in FVII protein concentrations (FVII:Ag). Consequently, studies on FVII now often include measurements of FVII:Ag. The present cross-sectional study examined the association between several behavioural variables (body mass index, physical activity, tobacco or alcohol consumption) or physiological variables (total cholesterol, HDL-cholesterol, triglycerides, glucose, insulin, fibrinogen, resting pulse, systolic blood pressure, bleeding time) and FVII:Ag in 439 51-y-old Danish men. In the multivariate analyses, body mass index (BMI), low physical activity, total cholesterol, short bleeding time, and insulin showed an independent positive association with FVII:Ag. The strongest independent association with FVII:Ag was found for total cholesterol. These results suggest that blood lipids are major determinants of FVII:Ag, but that other lifestyle factors such as insulin, BMI and physical activity can also influence FVII:Ag. Furthermore, the association between FVII:Ag and bleeding time suggests an effect of FVII or the FVII pathway on primary haemostasis.

The Arg353Gln polymorphism reduces the level of coagulation factor VII. In vivo and in vitro studies

Factor VII levels are regulated by environmental and genetic factors. Two polymorphisms, a G-to-A transversion at nucleotide 10,976 resulting in Arg353Gln and a decanucleotide insert at position -323 in the 5'-flanking region of the factor VII gene, have been associated with a 20% to 25% reduction in plasma factor VII levels. However Arg353Gln almost always segregates on alleles containing the insert in UK and Italian populations, thereby making it impossible to independently evaluate the impact of Arg353Gln on factor VII levels in these ethnic groups. We have evaluated the influence of genotype on factor VII levels in 99 healthy Polish blood donors and observed that Arg353Gln frequently occurs in the absence of the insert. In univariate analysis, the mean levels of factor VII coagulant activity (VII:C) and factor VII antigen (VII:Ag) were significantly lower in 16 people who were heterozygous for Arg353Gln and the insert compared with 72 normal subjects who had neither Arg353Gln nor the insert (88.8% of normal and 83.1% versus 102% and 100%, P = .019 and P = .0003, respectively). In nine subjects heterozygous for Arg353Gln alone, VII:C and VII:Ag were significantly decreased compared with the normal subjects (81.9% and 83%, respectively, P = .007 and P = .004). In multivariate analysis, Arg353Gln but not the insert significantly reduced VII:C and VII:Ag after adjustment for age and plasma triglycerides (P < .05 and P = .02, respectively). To evaluate the mechanism responsible for reduced factor VII levels in individuals with Arg353Gln, we performed transient transfection assays with factor VII cDNA containing the base substitution resulting in Gln353 and wild-type factor VII cDNA in COS-1 cells. The levels of VII:Ag in the cell lysates were similar, but the amino acid substitution significantly reduced factor VII secretion into the media to 74.9% of wild-type (P = .0001). Based on these in vivo and in vitro studies, we conclude that the Arg353Gln polymorphism alone can decrease plasma factor VII levels.

Genetic variation in factor VII associated with variation in plasma lipoprotein(a) concentration

Cross-sectional and prospective studies have shown that individuals with high plasma lipoprotein(a) [Lp(a)] concentrations are at increased risk for coronary heart disease. Size polymorphism of the apolipoprotein(a) [apo(a)] glycoprotein accounts for approximately 35% of the variation in plasma Lp(a) concentrations. However, there is no convincing evidence for associations between plasma Lp(a) and common genetic variation outside APO(a), the gene that encodes apo(a). We tested for association of common genetic variation of candidate genes in lipid metabolism and also of F7 with variation of plasma Lp(a) concentrations in Alberta Hutterites. Variation at codon 353 of F7 has been associated with variation in the plasma factor VII activity (FVIIc), with the 353Q allele associated with lower FVIIc and the 353R allele associated with higher FVIIc. We found significant associations between variation in plasma concentrations of Lp(a) and both apo(a) isoform size and F7 codon 353 genotype (both P < .0001). The effects on plasma Lp(a) concentration of the alleles at codon 353 were additive. The average effects of the F7 353Q and 353R alleles were, respectively, to decrease by 1.71 micrograms/mL and to increase by 0.301 microgram/mL plasma Lp(a) concentration from the sample mean. This suggests that common genomic variation in F7 is associated with variation in plasma Lp(a) concentration.

Fibrinogen and factor VIII, but not factor VII, are associated with measures of subclinical cardiovascular disease in the elderly. Results from The Cardiovascular Health Study

No studies have examined the associations of coagulation factor levels with measures of subclinical cardiovascular disease (CVD) in the elderly. The Cardiovascular Health Study (CHS) is a prospective, population-based cohort study of CVD in persons older than 65 years. At the baseline examination, we measured fibrinogen, factor VII, and factor VIII levels in 5024 of the 5201 participants of the CHS and examined the associations of these coagulation factors with measures of subclinical CVD in a cross-sectional analysis. Subclinical CVD measures were based on electrocardiography, carotid ultrasonography, echocardiography, and ankle-arm blood pressure measurements (AAI). For analyses, we used the full cohort as well as two mutually exclusive subgroups: those with prevalent clinical CVD at baseline and those without. Fibrinogen and to a lesser extent factor VIII showed positive associations with a variety of subclinical CVD measures. In age-adjusted analyses, fibrinogen and factor VIII were significantly associated with 8 of 10 measures. In multivariate analyses, fibrinogen was significantly associated with carotid artery stenosis, internal (but not common) carotid artery wall thickness, and AAI. Factor VIII was associated with abnormal wall motion and AAI in the full cohort only. Factor VII was not consistently associated with subclinical disease measures. In bivariate analyses that included data from all three groups, there were 5 positive subclinical disease associations and 5 negative associations for factor VII. In multivariate analyses, there were no significant associations between factor VII and subclinical CVD in the full cohort or in either subgroup. We conclude that in these cross-sectional analyses, fibrinogen and to a lesser extent factor VIII are associated with subclinical CVD in the elderly, even in those without symptoms or a history of clinical CVD. Factor VII, however, was not associated with subclinical CVD in the elderly.

Racial variation of factor VII activity and antigen levels and their correlates in healthy Chinese and Indians at low and high risk for coronary artery disease

Plasma factor VII activity (FVIIc) is one of the independent risk factors of coronary artery disease (CAD) and is controlled by both genetic and environmental factors. South Asians including Indians have one of the highest prevalence and mortality rates from CAD while the Chinese have a much lower risk. Generally accepted risk factors cannot explain the high mortality from CAD in Indians. We examined two hundred and seventy seven Chinese (124 m, 153 f); and 216 healthy Indian (150 m, 66 f) adults for serum lipids; plasma FVIIc and FVIIag levels in order to examine racial variations of these and their correlates in these two populations. Both Indian men and women had significantly higher FVIIc levels (12% and 11%, respectively) than the Chinese even after adjustments of age, BMI and lipids (P < 0.01). In contrast, Indians had significantly lower plasma FVIIag levels than Chinese (8% and 9%, respectively in men and women; P < 0.01). Multiple linear regression analysis shows a strong correlation of FVIIc with serum triglycerides accounting for 4-8% of the total variability of FVIIc in different groups. Further, there was a stronger correlation between FVIIc and FVIIag in Indians than that in the Chinese (0.43 vs. 25) suggesting a greater activation resulting in higher FVIIc in Indians inspite of lower FVIIag levels. The higher FVIIc and stronger activation by triglycerides observed in this study partly explain the higher risk of CAD in Indians.

Effect of cholesterol lowering on intravascular pools of TFPI and its anticoagulant potential in type II hyperlipoproteinemia

Tissue factor pathway inhibitor (TFPI) inhibits the extrinsic coagulation system. A major pool of TFPI is associated with the vascular endothelium and can be mobilized into the circulation by heparin. In circulating blood, TFPI is mainly associated with LDL (80%), whereas 10% to 20% is carrier free. In this study, heparin administration caused a 2.2-fold and a 7.5-fold increase in TFPI activity and TFPI antigen, respectively, in 25 patients with phenotypes IIa and IIb hyperbetalipoproteinemia. Because the antigen determination of TFPI almost exclusively measures carrier-free TFPI, more than 90% of the heparin-induced increase in TFPI activity was caused by mobilization of carrier-free TFPI from the vascular endothelium. Therapeutic lowering of total cholesterol (a decrease of 31.1 +/- 11.6%, P < .001) by 40 mg/d lovastatin in 17 patients with hyperbetalipoproteinemia was accompanied by a parallel decrease in TFPI activity (of 27.7 +/- 24.2%, P < .001) because of a reduction in LDL-TFPI complexes. However, drug intervention did not affect carrier-free TFPI or the magnitude of the vascular pool of TFPI that could be mobilized into the circulation by heparin. Moreover, this reduction of LDL-TFPI complexes did not reduce the anticoagulant potency of TFPI in plasma or of the vascular endothelial pool. The results of this study may imply that the anticoagulant potency of TFPI is associated with its carrier-free form in plasma or on the endothelium and that downregulation of LDL affects neither the size nor the anticoagulant potency of the endothelial pool of TFPI.

The protein concentration of blood coagulation factor VII can be measured equally well in plasma and serum

In the Northwick Park Heart Study, the coagulant activity of factor VII (FVII:C) has been identified as a risk marker of ischaemic heart disease. In the fasting state, the protein concentration of FVII (FVII:Ag) might be an even better risk marker, because of the low coefficient of variation of the antigen assay. Today, most analyses are performed in plasma samples, as it is unknown whether FVII, to some extent, is consumed during coagulation. In the present study, we have investigated, whether FVII:Ag can be measured equally well in plasma and serum. FVII:Ag was measured in 88 plasma and serum samples. Results were compared by means of linear regression, where y = 0.984 x +0.770, r = 0.96. No systematic variation existed between FVII:Ag in plasma and serum. The mean difference in FVII:Ag between plasma and serum was -1.17 (SD 11.92) arbitrary units, compared with a mean difference of 0.18 (SD 8.31) arbitrary units between duplicate measurements of the same plasma dilution. Our findings indicate that there is a good agreement between FVII:Ag in plasma and serum.

Association of factor VII genotype with plasma factor VII activity and antigen levels in healthy Indian adults and interaction with triglycerides

Plasma factor VII activity (factor VIIc) is one of the independent risk factors for coronary artery disease and is controlled by both genetic and environmental factors. Several studies in healthy Caucasian subjects have revealed an association of a common genetic polymorphism at residue 353 (Arg-->Gln) of the factor VII gene with plasma factor VIIc. We have investigated the influence of this polymorphism (factor VII Arg/Gln353) on fasting plasma factor VIIc and antigen (factor VIIag) levels and its interaction with triglyceride levels in 185 healthy Dravidian Indians of both sexes (128 men, 57 women). The frequency of Gln353 has been found to be significantly higher in Dravidian Indians (0.29; confidence interval, 0.27 to 0.30) than in Caucasians (0.10). The distribution of factor VII Arg/Gln353 genotypes was at Hardy-Weinberg equilibrium. The carriers of the Gln353 allele had significantly lower plasma factor VIIc and factor VIIag in men (P < .05). The factor VII Arg/Gln353 polymorphism explained 13% and 11% of the total variance of plasma factor VIIc and factor VIIag, respectively, in men (P < .001) and 6% and 9% in women (P > .1). The genotype-specific correlation of factor VIIc and factor VIIag with triglyceride levels was stronger in carriers of the Gln353 allele (r = .38 and .41; P < .001) than in Arg353 homozygotes (r = .09 and .27; P = .19 and .005, respectively).

Correlation of vitamin K-dependent clotting factors with cholesterol and triglycerides in healthy young adults

The plasma level of factor VII activity was a risk factor for the development of ischemic heart disease (IHD) in a prospective epidemiological study of hemostatic factors. We have previously reported significant correlations between factor VII clotting activity or antigen and lipid fractions in a group of 132 young men (< 30 years old) at low risk for IHD and concluded that control of the plasma factor VII level may be linked to lipid metabolism in normal male physiology. Because factor VII is one of four vitamin K-dependent procoagulant proteins, we hypothesized that plasma levels of all these proteins would be similarly controlled in normal physiology. In an extension of this study, we have measured two additional vitamin K-dependent clotting factors (prothrombin [factor II] and factor X activity), as well as factor VII activity and antigen and fasting serum lipid fractions in healthy young men and women (< 30 years old) at low risk for IHD. In the women, we found significant positive correlations of factor VII antigen with total or HDL cholesterol and of prothrombin or factor X with total or LDL cholesterol. In the men, factor VII activity or antigen correlated with total cholesterol, triglycerides, HDL cholesterol, or LDL cholesterol; prothrombin or factor X correlated with total cholesterol, triglycerides, or LDL cholesterol. In contrast, we found no significant correlations of fibrinogen with any of the lipid fractions in our groups of men or women. Our data support the hypothesis that control of the levels of the vitamin K-dependent procoagulant proteins is linked to lipid metabolism in the normal physiology of both men and women.

Fibrinolytic and thrombotic factors in atherosclerosis and IHD: the influence of triglyceride rich lipoproteins (TGRLP)

TGRLP interactions with the endothelium may increase the likelihood that a suppressed fibrinolytic capacity and/or an increased procoagulant activity enhances the risk for an ischemic event, that is, for the production of a focal thrombus. The cellular mechanisms and characteristics of TGRLP in hyperlipemia and in the postprandial state that contribute to their potential pathology in IHD are considered.

Factor VII coagulant activity and cholesterol changes in premenopausal women consuming a long-term cholesterol-lowering diet

We periodically obtained blood samples from mildly hypercholesterolemic, but otherwise healthy, premenopausal women who were recruited to participate in a study of a long-term, cholesterol-lowering diet. All meals were prepared and most meals were consumed in the study center dining facility. Tests performed on blood samples included fibrinogen, cholesterol, factor VII coagulant activity (VIIc), and other measures of factor VII. We found that when women switched from a typical American diet (37% fat, polyunsaturated fatty acid to saturated fatty acid [P/S] ratio 0.5, 300 mg cholesterol/d) to a diet lower in fat and cholesterol (American Heart Association phase 2 diet: 30% fat, P/S ratio of 1, 150 to 200 mg cholesterol/d) and maintained that diet for 20 weeks, their plasma cholesterol levels decreased by approximately 6% after 4 weeks and remained at that level until study termination. Likewise, VIIc decreased by approximately 11% while factor VII antigen, total factor VII activity, and fibrinogen concentration did not change appreciably from baseline values. Our results show that premenopausal women benefit from a diet lower in total and saturated fat by a reduction in blood cholesterol and VIIc. Extrapolation from data on men in the Northwick Park Heart Study indicates that the 11% decrease in VIIc activity would correspond to an approximately 30% decrease in risk of mortality from coronary heart disease.

Simvastatin in non-insulin-dependent diabetes mellitus: effect on serum lipids, lipoproteins and haemostatic measures

The clinical efficacy of the 3-hydroxy-3-methyl-glutaryl-coenzyme A (HMGCoA) reductase inhibitor simvastatin in the treatment of hypercholesterolaemia in non-insulin-dependent diabetes (NIDDM), was examined in a double-blind placebo-controlled study of 6 months in 70 patients with NIDDM (age 25-70 years), of whom 57 were randomised to placebo (29 patients) or simvastatin for 6 months, following a 3-month run-in on diet. Patients were hypercholesterolaemic (7.8 (7.6-8.0) (mean (95% confidence intervals)) mmol/l simvastatin vs. 8.0 (7.7-8.5) mmol/l placebo) and mildly hypertriglyceridaemic (2.6 (2.2-3.0) simvastatin vs. 2.9 (2.3-3.5) placebo). Other lipid measures and estimates of glycaemic control and haemostasis were similar in both groups. There were no significant changes in lipids, haemostatic factors, or measures of glycaemic control in the placebo treatment group. Conversely by the end of 24 weeks, simvastatin produced a 28% reduction in cholesterol (to 5.6 (5.0-6.2) mmol/l (P < 0.001)), a 38% reduction in LDL cholesterol (from 5.5 (5.4-5.6) mmol/l to 3.4 (2.8-4.0) mmol/l, P < 0.001), a 15% reduction in triglyceride (to 2.2 (1.8-2.6) mmol/l, P < 0.05, and a 9% rise in HDL (from 1.16 (1.07-1.25) to 1.23 (1.14-1.32) mmol/l, P < 0.05). Improvements in apolipoprotein B (apo B) (-28%, P < 0.001), the LDL cholesterol to apo B ratio (-20%, P < 0.001), and apo A1 (+15%, P < 0.001) were recorded. There were no effects upon fibrinogen, factor VII activity, factor VIII activity, or measures of glycaemic control (fasting glucose, insulin, C-peptide, or HbA1).(ABSTRACT TRUNCATED AT 250 WORDS)

Dietary fat induces changes in factor VII coagulant activity through effects on plasma free stearic acid concentration

Previous studies have demonstrated activation of the contact system of coagulation and an increase in factor VII coagulant activity (VIIc) when citrated plasma is incubated in the presence of micellar stearate. The products of contact activation, factors XIIa and IXa, were responsible in this system for the activation of factor VII, thereby increasing factor VIIc. To obtain evidence that these in vitro interactions also operate in vivo, factor VIIc was examined in relation to plasma free fatty acid concentrations in five healthy individuals during the consumption of isocaloric high-saturated fat, high-unsaturated fat, and low-fat diets, each taken for 4 weeks in random order and separated by intervals of 12 weeks. For all but the final 3 days of each phase, subjects selected appropriate foods from prepared lists to meet the dietary requirements. Experimental diets of predetermined fat content and composition were fed on days 26 through 28 in each phase. Fat supplied on average 62% of energy in two of the experimental diets and less than 20% of energy in the third. On the final day of each dietary phase, the concentrations of the various free fatty acids and factor VIIc were measured before breakfast and at three 150-minute intervals thereafter. Plasma factor VIIc was, respectively, 6.5% and 13.1% of standard higher on the unsaturated and saturated fat diets than on the low-fat diet. Furthermore, the plasma concentration of stearic acid was strongly associated with factor VIIc (r = .58; P < .0001), and this relation remained significant (P = .003) after allowance for the plasma concentrations of palmitic, oleic, and linoleic acids.(ABSTRACT TRUNCATED AT 250 WORDS)

Factor VII coagulant activity and antigen levels in healthy men are determined by interaction between factor VII genotype and plasma triglyceride concentration

Ischemic heart disease is caused by a combination of and interaction between a number of genetic and environmental factors. In a study of a group of healthy men from the United Kingdom, such an interaction was identified between the levels of plasma triglycerides and genetic variation determining plasma levels of factor VII, a clotting factor that is associated with risk of ischemic heart disease. We previously reported a common genetic polymorphism of the factor VII gene that changes arginine at residue 353 to a glutamine (Arg353-->Gln) and showed that healthy men who carry the allele for Gln353 had lower plasma levels of factor VII coagulant activity. This association is strongly confirmed in a new sample. Compared with 301 men with the allele for Arg353, 63 men with one or two alleles for Gln353 had levels of factor VII coagulant activity that were 20% lower (97.8% [95% confidence interval (CI), 95.2% to 100.4%] and 78.2% [CI, 73.8% to 82.9%], respectively; P < .0001), with similar genotype-associated differences observed for levels of factor VII antigen. The 6 men who were homozygous for the Gln353 allele had mean levels of factor VII coagulant activity and antigen that were lower by 40% and 50%, respectively. In an assay using bovine thromboplastin, which is specific for the cleaved (activated) form of factor VII, they had levels lower by 60%, suggesting that the major effect of the Gln353 substitution is to reduce the proportion of the circulating zymogen that is activated.(ABSTRACT TRUNCATED AT 250 WORDS)

Tissue-factor pathway inhibitor and lipoproteins. Evidence for association with and regulation by LDL in human plasma

Tissue-factor pathway inhibitor (TFPI) is a potent inhibitor of extrinsic coagulation, which is mainly associated with lipoproteins in circulating blood. Gel filtration of human plasma confirmed the presence of three peaks in which approximately 10%, 70%, and 20% of total TFPI activity was retained. Precipitation of very-low-density lipoproteins and low-density lipoproteins (LDLs) in plasma by polyethylene glycol almost completely abolished peaks and I and II. LDL isolated by ultracentrifugation revealed two peaks of TFPI after gel filtration that coeluted with peaks I and II, respectively, from gel filtration of total plasma. TFPI activity in peaks I and II was also precipitated by anti-apolipoprotein B antibodies. Fourteen patients with familial hypercholesterolemia had higher plasma TFPI activity than did age- and sex-matched normolipemic control subjects (1.45 +/- 0.27 U/mL versus 0.80 +/- 0.09 U/mL, P < .001). Plasma TFPI was correlated with LDL cholesterol (r = .73, P < .001) and apolipoprotein B (r = .69, P < .001). No association was found with high-density lipoprotein cholesterol or apolipoprotein A-I. In a double-blind, placebo-controlled trial among the familial hypercholesterolemia patients, lovastatin alone or in combination with fish oil concentrate lowered plasma TFPI in parallel with LDL cholesterol. Gel filtration of plasma from these patients demonstrated a specific drop in apolipoprotein B-TFPI complexes, whereas TFPI not associated with lipoproteins was unchanged. This study demonstrated that plasma TFPI was associated with and regulated by LDL in plasma from healthy subjects and patients with familial hypercholesterolemia.

The inter-relationship of factor VII and its activity state with plasma lipids in healthy male adults

A close inter-relationship between raised factor VII clotting activity and elevated blood lipids, particularly serum triglycerides, is well established. A study of factor VII, its activation state and of plasma lipids has been undertaken in two groups of healthy middle-aged males to elucidate this mechanism. A control group with normal factor VII levels were closely matched for age and body-mass index with a second group with elevated levels. Factor VII assays, using rabbit and bovine thromboplastin and a factor VII Ag method, were employed. Triglycerides correlated with the rabbit factor VII thromboplastin assay and factor VII Ag (P < 0.05) but not with the bovine thromboplastin method. Higher HDL-cholesterol and apolipoprotein A-I levels were found in subjects with increased factor VII (P < 0.001) and appeared to be due to differences in alcohol consumption. Cholesterol levels were significantly higher with elevated factor VII. Differential testing suggests that higher factor VII is predominantly mediated through a rise in total VII, rather than an increase in its activity state.

Cholesterol and lipoproteins: beyond atherogenesis

Although much emphasis has been placed on the role of cholesterol and lipoproteins in atherosclerotic plaque formation, recent studies suggest that lipids have other vascular actions which may contribute to the pathogenesis of myocardial ischemia. These include deleterious effects of lipids on platelet and endothelial cell function, coagulation, fibrinolysis, and prostacyclin metabolism. The purpose of this report is to review recent data regarding the nonatherogenic effects of lipids and provide insight as to how lipid lowering might contribute to clinically important improvements in vascular biology.

The distribution of coagulation factors VII and VIII and fibrinogen in adults over 65 years. Results from the Cardiovascular Health Study

The Cardiovascular Health Study (CHS) was designed to examine cardiovascular disease and its risk factors in older adults. We report here the distributions of the coagulation factors fibrinogen, factor VII, and factor VIII in a population-based cohort of men and women 65 years or older. In other studies of middle-aged individuals, these factors were shown to be associated with cardiovascular risk. In the CHS cohort, all three factors were elevated, compared to levels reported in middle-aged individuals, and fibrinogen and factor VIII values were higher in each successive age group; factor VII values, in contrast, declined slightly with age in the CHS cohort. Compared to white subjects, blacks had higher values for fibrinogen and factor VIII and lower values for factor VII. While women had markedly higher values for factor VII and factor VIII than men at all ages in the CHS, mean fibrinogen values were not different between men and women.

Correlation of factor VII activity and antigen with cholesterol and triglycerides in healthy young adults

Prospective epidemiological studies found that the plasma level of factor VII activity was a risk factor for ischemic heart disease (IHD). Our laboratory previously demonstrated that young adults (mean age, 35 years) at high risk of IHD had significantly higher plasma factor VII activity and antigen levels than did comparable young adults at low risk. To study the relation of factor VII with lipid metabolism in even younger adults (less than 30 years), using standard techniques we measured plasma factor VII activity and antigen, plasma fibrinogen, and fasting serum lipid fractions in healthy male and female subjects who were at low risk of IHD and who were not on medication. Factor VII antigen correlated significantly with total serum cholesterol, fasting serum triglycerides, and high density lipoprotein (HDL) and low density lipoprotein (LDL) cholesterol (p less than 0.01), and factor VII activity correlated with total and HDL cholesterol (p less than 0.05) in the men (n = 132); however, fibrinogen level did not correlate significantly with any lipid level in this group. We found no significant correlation of factor VII activity or antigen with any lipid levels in the women (n = 65). Our data support the hypothesis that control of plasma factor VII level is linked to lipid metabolism in normal physiology in men. Thus, factor VII level may reflect the mechanism by which male gender imparts added risk for IHD, independent of other established risk factors. This study also supports the use of the factor VII antigen assay, a highly reproducible method, in studies of the relation of factor VII to the risk of IHD.

Elevation of factor VII activity and mass in coronary artery disease of varying severity

The present study was undertaken to determine whether the extent of Factor VII elevation correlated with the severity of coronary artery disease and whether zymogen or activated Factor VII was responsible for this elevation. A group of 69 patients with coronary artery disease with old myocardial infarction was compared with 28 control subjects. The patient groups showed elevated levels of Factor VII procoagulant activity (FVII:C) and more markedly elevated Factor VII antigen (FVII:Ag) levels than the control group; therefore they had a decreased FVII:C to FVII:Ag ratio. The increased Factor VII level in the patient groups was caused by elevated Factor VII zymogen levels, and not by activated Factor VII. Since FVII:C levels strongly correlated with the titer of thrombin-antithrombin III complexes in all patients, the hypercoagulable state accompanying severe coronary atherosclerosis seems to underlie the increase of FVII and TAT in the stable phase of myocardial infarction.

Effect of fish diet versus meat diet on blood lipids, coagulation and fibrinolysis in healthy young men

Twelve healthy young men followed a 10-d controlled diet that included 210 g of fatty fish d-1. The diet was repeated after 18 d, but with lean meat substituted for fish. Blood samples were collected for assessment of serum lipids and haemostatic variables in the plasma. Both experimental diets caused serum triglycerides and plasma factor VIIc to decline to the same extent. The meat diet was also associated with significant changes in plasma levels of tissue plasminogen activator (t-PA) antigen. PA inhibitor type I (PAI-1) antigen, PAI activity, and t-PA activity of the euglobulin fraction of plasma. The fish diet left these variables unchanged from initial values. Thus, in a paired comparison of the two diets, the fish diet was associated with higher levels of t-PA antigen (5.4 vs. 4.7 g ml-1), which is considered to be beneficial with regard to prevention of cardiovascular disease. However, the fish diet was concurrently associated with the putative unfavourable higher levels of PAI-1 antigen (3.0 vs. 1.2 ng ml-1) and PAI activity (6.1 vs. 3.2 IU ml-1), and lower t-PA activity (80 vs. 140 mIU ml-1). Thus it is unclear which of the two diets has the greatest potential in the prevention of cardiovascular disease.

Hemorheologic and coagulative pattern in hypercholesterolemic subjects treated with lipid-lowering drugs

The effects on the coagulative and rheologic pattern of two lipid-lowering drugs, bezafibrate and simvastatin, were studied in 36 hypercholesterolemic subjects. Patients were randomly divided into two groups (18 subjects each) and received bezafibrate R 400 mg/day or simvatatin 10-40 mg/day over a twelve week period. Besides a decrease in plasma fibrinogen and fibrinopeptide A (p less than 0.001 both), bezafibrate induced a reduction of factor VIIc and VIIIc activity (p less than 0.001 both), while antithrombin 3 activity was increased (p less than 0.001) and the hemorheologic pattern was greatly improved (p less than 0.001). Simvastatin caused a slight decrease in factor VIIIc activity and a moderate reduction of beta-thromboglobulin. The efficacy of bezafibrate in reducing the activation of the coagulative cascade and improving the hemorheologic pattern has been confirmed; the peculiar triglycerides- and fibrinogen-lowering effect of the drug, not observed with simvastatin, could be responsible for these modifications.

Plasma triglyceride and coronary heart disease

Although the literature on epidemiological associations between plasma triglyceride and CHD is not completely consistent, trends do emerge from the studies described here. First, the majority of observational studies demonstrate a significant univariate relation, although the results of case-control and cross-sectional studies are more uniform than those from prospective study designs. In many but not all studies, triglyceride remains a significant predictor of CHD in multivariate statistical analyses after controlling for TC or LDL-C. Perhaps the least consistent result is that the triglyceride association does not persist in some analyses controlling for HDL-C, while in other studies, the association remains significant. Although most studies have been conducted in men, the studies providing data on women, normocholesterolemic subjects, and diabetic subjects have generally found triglyceride to be, at the very least, a univariate risk factor. The results of intervention trials differ considerably, but no such study to date has been specifically designed to evaluate triglyceride-lowering effects on primary prevention of CHD. Important statistical properties must be taken into consideration in evaluating triglyceride as a risk factor for CHD. The large variability of triglyceride measurements and the correlation of triglyceride values with other lipid measures appears to result in the underestimation of the association between triglyceride and disease in multivariate analyses. Finally, individual genetic susceptibility may play an important role in the relation between plasma triglyceride levels and CHD. For example, risk of CHD clearly varies among the well-established familial forms of hypertriglyceridemia. A predominance of small, dense, LDL particles (LDL subclass pattern B) also appears to be a genetic trait associated with both increased risk of MI and increases in plasma triglyceride levels.

Gemfibrozil in hyperlipidaemic patients with peripheral arterial disease: some undiscovered actions

The effects of gemfibrozil were assessed in 27 hyperlipidaemic patients with stable peripheral arterial occlusive disease. Gemfibrozil (600 mg twice daily) was administered for 12 weeks after 2 weeks of placebo medication, thus enabling patients to act as their own controls. Serum cholesterol levels were reduced by a mean of 11.3%, triglycerides by 42.3% and low density lipoprotein cholesterol by 19.9%. Small but significant increases in HDL3 and apolipoprotein A-II also occurred. New findings included significant reductions in plasma lipid peroxides and Factor VIIc levels and a mean increase of 19% in antithrombin III concentrations. Furthermore, plasma fibrinogen levels increased by a mean of 17.6%, a potentially adverse effect of gemfibrozil that has not been previously reported.

Effects of total fat content and fatty acid composition in diet on factor VII coagulant activity and blood lipids

In a strictly controlled cross-over study (twice 2 weeks) of 11 healthy adults, the effects of a low-fat diet (32% of total energy from fat) with a low or a high ratio of polyunsaturated to saturated fatty acids (0.28 and 0.89, respectively) were observed. Factor VII activity and antigen levels, serum cholesterol, HDL-cholesterol and triglycerides were measured. Factor VII activity was determined in clotting assays using human and bovine thromboplastin (interacting primarily with activated factor VII, F VIIa), allowing differentiation between F VIIc and F VIIa. A significant decrease of F VII levels (median 11.0-14.5%, P less than 0.05) and triglycerides (median 0.22-0.27 mmol/l, P less than 0.05) was observed on both diets, while only the highly unsaturated diet reduced serum cholesterol levels (median 0.65 mmol/l, P less than 0.001). There were no significant correlations between changes in blood lipids and F VIIc. Low fat diets may reduce the risk for ischemic heart disease without lowering of cholesterol levels by eliminating states of hypercoagulability such as elevated factor VII coagulant activity.