Factor VII in an industrial population

Peak flow rate and death due to coronary heart disease: 30-year results from the Northwick Park Heart cohort study

Objective

Numerous studies have reported that chronic obstructive pulmonary disease or impaired lung function are associated with later coronary heart disease (CHD). However, it is unclear if lung function is an independent risk factor, as many of these studies have included only limited measures of other factors associated with CHD.

Methods

In total 2167 men of all ages in the first Northwick Park Heart Study were followed for a median of 30 years. Cox regression models were used to assess the relationship between peak flow rate (PFR) and CHD mortality adjusted for potential confounders measured at baseline. Analyses allowed for missing data, and secondary analyses for repeat measures on some men and competing risks of CHD death.

Results

There were 254 CHD deaths with some evidence of an association between PFR and CHD mortality. The adjusted HRs (95% CIs) from the lowest to the highest of four PFR quartiles were 1.53 (1.04 to 2.25), <430 L/min; 1.43 (0.99 to 2.08), 430 – <490 L/min; and 1.31 (0.93 to 1.86), 490 – <550 L/min; compared with the reference group of ≥550 L/min (trend test p=0.025). Other associations with CHD mortality were observed for systolic blood pressure (p<0.0001), body mass index (p=0.0002), smoking status (p=0.015), blood cholesterol (p=0.005), plasma fibrinogen (p=0.001) and high-risk ECG (p=0.021). There were no strong associations for factors V and VIII or platelet count.

Conclusions

After allowing for a range of other risk factors associated with CHD, there was only limited evidence of a relation between PFR and CHD mortality.

The Northwick Park Heart Study: evidence from the laboratory

The Northwick Park Heart Study (NPHS) has shown associations of high plasma fibrinogen and factor VII (FVIIc) levels with the risk of death from coronary heart disease (CHD). The finding for fibrinogen has been confirmed in many other studies. Whereas one further study has found a similar prospective association for FVIIc, several have not. Experimental studies have demonstrated the impact that the coagulation activity of fibrinogen and FVIIc have on the progression and phenotype of atherosclerotic lesions. FVIIc-driven thrombin generation and fibrin formation within the vessel wall are important determinants of both plaque (in)stability and atherothrombosis. In blood, local concentrations of FVIIc and thrombin may be sufficient to allow interactions between these serine proteases and protease-activated receptors, to drive cellular inflammatory reactions that further promote these processes. Local fibrinogen concentrations dictate fibrin clot structure and resistance to fibrinolysis. Within the atherosclerotic plaque, coagulation reactions driven by proinflammatory stimuli may initially support lesion stability (as part of wound healing), but, with advanced inflammation, thrombin and fibrin generation diminish because of proteolytic activity contributing to plaque instability. The NPHS findings have proved controversial, but, in the light of current knowledge, a reappraisal of the importance of FVIIc and fibrinogen in atherosclerosis, atherothrombosis and CHD is justified. Hypercoagulability, reflected in turn by thrombin generation capacity, and local concentrations of coagulation proteins, including FVIIc and fibrinogen, is linked to plaque phenotype, and even minute local concentrations of fibrinogen and proteases such as FVIIc may affect thrombin generation capacity.

A gene-centric association scan for Coagulation Factor VII levels in European and African Americans: the Candidate Gene Association Resource (CARe) Consortium

Polymorphisms in several distinct genomic regions, including the F7 gene, were recently associated with factor VII (FVII) levels in European Americans (EAs). The genetic determinants of FVII in African Americans (AAs) are unknown. We used a 50,000 single nucleotide polymorphism (SNP) gene-centric array having dense coverage of over 2,000 candidate genes for cardiovascular disease (CVD) pathways in a community-based sample of 16,324 EA and 3898 AA participants from the Candidate Gene Association Resource (CARe) consortium. Our aim was the discovery of new genomic loci and more detailed characterization of existing loci associated with FVII levels. In EAs, we identified three new loci associated with FVII, of which APOA5 on chromosome 11q23 and HNF4A on chromosome 20q12-13 were replicated in a sample of 4289 participants from the Whitehall II study. We confirmed four previously reported FVII-associated loci (GCKR, MS4A6A, F7 and PROCR) in CARe EA samples. In AAs, the F7 and PROCR regions were significantly associated with FVII. Several of the FVII-associated regions are known to be associated with lipids and other cardiovascular-related traits. At the F7 locus, there was evidence of at least five independently associated SNPs in EAs and three independent signals in AAs. Though the variance in FVII explained by the existing loci is substantial (20% in EA and 10% in AA), larger sample sizes and investigation of lower frequency variants may be required to identify additional FVII-associated loci in EAs and AAs and further clarify the relationship between FVII and other CVD risk factors.

Haplotype and genotype effects of the F7 gene on circulating factor VII, coagulation activation markers and incident coronary heart disease in UK men

BACKGROUND

Evidence for the associations of single nucleotide polymorphisms (SNPs) in the F7 gene and factor (F)VII levels and with risk of coronary heart disease (CHD) is inconsistent. We examined whether F7 tagging SNPs (tSNPs) and haplotypes were associated with FVII levels, coagulation activation markers (CAMs) and CHD risk in two cohorts of UK men.

METHODS

Genotypes for eight SNPs and baseline levels of FVIIc, FVIIag and CAMs (including FVIIa) were determined in 2773 healthy men from the Second Northwick Park Heart Study (NPHS-II). A second cohort, Whitehall II study (WH-II, n = 4055), was used for replication analysis of FVIIc levels and CHD risk.

RESULTS

In NPHS-II the minor alleles of three SNPs (rs555212, rs762635 and rs510317; haplotype H2) were associated with higher levels of FVIIag, FVIIc and FVIIa, whereas the minor allele for two SNPs (I/D323 and rs6046; haplotype H5) was associated with lower levels. Adjusted for classic risk factors, H2 carriers had a CHD hazard ratio of 1.34 [95% confidence interval (CI): 1.12-1.59; independent of FVIIc], whereas H5 carriers had a CHD risk of 1.29 (95% CI: 1.01-1.56; not independent of FVIIc) and significantly lower CAMs. Effects of haplotypes on FVIIc levels were replicated in WH-II, as was the association of H5 with higher CHD risk [pooled-estimate odds ratio (OR) 1.16 (1.00-1.36), P = 0.05], but surprisingly, H2 exhibited a reduced risk for CHD.

CONCLUSION

 tSNPs in the F7 gene strongly influence FVII levels. The haplotype associated with low FVIIc level, with particularly reduced functional activity, was consistently associated with increased risk for CHD, whereas the haplotype associated with high FVIIc level was not.

Recombinant-activated factor VII for control and prevention of hemorrhage in nonhemophilic pediatric patients

A total of 108 episodes among 103 nonhemophilic pediatric patients (nine newborns, 16 infants and 78 children) treated with recombinant factor-activated VII (rFVIIa) were evaluated retrospectively. These episodes were divided into two groups: group 1 included 86 occurrences for hemorrhagic control of ongoing massive bleeding due to thrombocytopenia and coagulopathy unresponsive to blood component therapy in patients with dengue hemorrhagic fever, life-threatening, intraoperative and postoperative bleeding; group 2 included 22 episodes for prevention of hemorrhage with invasive procedures in patients with chronic liver disease and associated coagulopathy, and patients without preexisting hemostatic disorder but at high risk due to their underlying diagnosis and required surgical intervention. The effective control of hemostasis response rate in group 1 was significantly lower than in group 2. The median total dose per kilogram of rFVIIa group 1 was twice that of group 2. The overall case-fatality rate related to bleeding or underlying conditions was 31.1% (32/103). Adverse events were observed in three patients (2.9%) receiving rFVIIa for control of intraoperative and postoperative bleeding in the setting of corrective cardiac surgery. These results support the safety and potential benefit of rFVIIa for control and prevention of hemorrhage in pediatric patients without congenital hemophilia.

Long-term effects of hemostatic variables on fatal coronary heart disease: 30-year results from the first prospective Northwick Park Heart Study (NPHS-I)

BACKGROUND

The long-term associations of established risk factors for coronary heart disease (CHD), for example cholesterol, are well known, but not for the less familiar hemostatic variables.

OBJECTIVES

To establish whether associations between hemostatic variables and CHD first identified nearly three decades ago have persisted long-term.

METHODS

The first Northwick Park Heart Study (NPHS-I) recruited 2167 white men and 941 white women, average age at entry 48 years, on whom measures of factor (F) VII activity (VIIc) and plasma fibrinogen were carried out, both at entry and at follow-up approximately 6 years later.

RESULTS

During a median follow-up of 29 years, 231 male and 36 female CHD deaths were recorded from notifications by the Office for National Statistics. VIIc at recruitment was significantly related to CHD mortality, corrected rate ratio, RR, per 1 SD increase 1.56 (95% CI 1.29, 1.88) in men and RR 1.78 (95% CI 1.17, 2.72) in women. Recruitment fibrinogen was also strongly related to CHD mortality in men, RR 1.63 (95% CI 1.33, 1.99) but not in women, RR 0.75 (95% CI 0.40, 1.43). The associations persisted after controlling for confounders and were confirmed using 6-year follow-up measurements and in analyses omitting deaths within 10 years of recruitment.

CONCLUSIONS

The hemostatic system contributes to CHD mortality, and its effect is stable over time. For VIIc, the effect was similar in men and women, while for fibrinogen it appeared to be present only in men.

Associations of plasma fibrinogen and factor VII clotting activity with coronary heart disease and stroke: prospective cohort study from the screening phase of the Thrombosis Prevention Trial

BACKGROUND

As with 'conventional' risk factors such as cholesterol and smoking, there is a need for large, long-term prospective studies on hemostatic factors.

OBJECTIVES

To investigate the prospective relationship of fibrinogen and factor VII clotting activity (FVIIc) with risk of coronary heart disease (CHD) and stroke in a study with a large number of outcomes over a period of 15 years.

PATIENTS/METHODS

A cohort of 22 715 men aged 45-69 years was screened for participation in the Thrombosis Prevention Trial. Men were followed up for fatal and non-fatal CHD and stroke events. There were 1515 CHD events (933 CHD deaths) and 391 strokes (180 stroke deaths). Hazard ratios (HRs) and 95% confidence intervals are expressed per standardized increase in log fibrinogen and log FVIIc, adjusting for age, trial treatment group, conventional CHD risk factors and regression dilution bias.

RESULTS

Hazard ratios for fibrinogen were 1.52 (1.37-1.70) for all CHD events, and 1.36 (1.09-1.69) for all strokes. Exclusion of events within the first 10 years showed a persistent association between CHD and fibrinogen, with an adjusted HR of 1.93 (1.42-2.64). The HRs for FVIIc, adjusting for age and trial treatment, were 1.07 (1.01-1.12) for all CHD events and 1.07 (0.97-1.20) for all strokes, and the fully adjusted HRs were, respectively, 0.97 (0.84-1.05) and 1.07 (0.85-1.33).

CONCLUSIONS

The persisting association between fibrinogen and CHD beyond 10 years may imply a causal effect. There is a small effect of FVIIc on CHD, after adjustment for age and trial treatment, but no association independent of other risk factors.

Activation of human coagulation system by liver-derived clotting factors of banna minipig inbred line

The liver synthesizes most of the coagulation factors that play a major role in arresting hemorrhage. Matching hepatic coagulation factors is an important premise in successful xenotransplantation. As a unique inbred pig, the Banna minipig inbred (BMI) animals have a huge potential value for pig-to-human xenotransplantation, due to its clear genetic background and tiny interindividual differences. Whether the coagulation factors synthesized by porcine liver can trigger human clotting pathways has not been reported. This study focused on the activities of BMI coagulant factors synthesized exclusively by the liver to activate human clotting pathways. In these experiments we prepared coagulant factors II, V, VII, X, and XII synthesized exclusively by liver from BMI and humans. The factors were used in common correction tests, added to the corresponding factor-deficient human plasma to determine prothrombin times or activated partial thromboplastin time, thereby calculating BMI and human coagulant factor activities. BMI clotting factors XII, VII, and X triggered human intrinsic, extrinsic, and common pathways, respectively. BMI clotting factors II, V, VII, X, and XII activities were 3.2-, 3.7-, 4.7-, 2.9-, and 4.5-fold as potent as those from humans.

Fish as bioreactors: transgene expression of human coagulation factor VII in fish embryos

A plasmid containing human coagulation factor VII (hFVII) complementary DNA regulated by a cytomegalovirus promoter was microinjected into fertilized eggs of zebrafish, African catfish, and tilapia. The active form of hFVll was detected in the fish embryos by various assays. This positive expression of human therapeutic protein in fish embryos demonstrates the possibility of exploitation of transgenic fish as bioreactors.

The use of recombinant activated factor VII for controlling life-threatening bleeding in Dengue Shock Syndrome

To report the use of recombinant activated factor VII (rFVIIa) in controlling life-threatening bleeding episodes in patients with grades III and IV Dengue Hemorrhagic Fever (DHF), also known as Dengue Shock Syndrome. Fifteen patients (seven boys, eight girls), whose median age was 8 years, were enrolled in the study. They were divided into two groups. Group 1 included nine patients, mainly grade III, waiting for platelet concentrate, and group 2 included six patients, mainly grade IV, who had already received platelet concentrate with unresponsiveness. A single dose or repeated doses of 100 microg/kg rFVIIa was/were given at intervals of 4 h according to the bleeding symptoms. The median times from the onset of bleeding to rFVIIa initiation were 6.5 and 29.8 h in groups 1 and 2, respectively. Each patient received one to three doses. An effective response was found in eight patients (53.3%), including six patients in group 1 and two patients in group 2. They had complete cessation of bleeding without recurrence for 48 h. An ineffective response was found in seven patients (46.7%) including three patients in group 1 and four patients in group 2 for which the bleeding recurred (n = 2), temporarily slowed down (n = 3), continued (n = 1) or occurred at a new site (n = 1). These included three patients in profound shock 24-48 h before referral to comprehensive treatment centers, two patients receiving ibuprofen before hospitalization, one patient with extensive volume overloading, and one patient requiring surgical intervention to ligate the torn intercostal artery and vein. The platelet concentrate was promptly transfused to stop bleeding in patients with ineffective responses. The results revealed that the earlier initiation of rFVIIa in the mainly grade III DHF in group 1 yielded a higher effective response (66.7%) than the delayed initiation in the mainly grade IV DHF in group 2 (33.3%). Moreover, patients previously receiving ibuprofen or volume expander of low molecular weight dextran or urea-linked gelatin tended to have lower effective responses (28.6%) than patients without associated medication (75.0%). Ultimately, three of six patients with grade IV DHF died, while all nine patients with grade III DHF survived. Thus, the case-fatality rate in this study was 20%. No clinical evidence of thromboembolic complications was observed. rFVIIa seems to be effective in restoring hemostasis in a limited series of patients with Dengue Shock Syndrome exhibiting life-threatening bleeding episodes. Further study is warranted.

Recombinant activated factor VII combined with local measures in preventing bleeding from invasive dental procedures in patients with Glanzmann thrombasthenia

Recombinant activated factor VII (rFVIIa), combined with local measures of fibrin glue and a celluloid splint, preventing bleeding from four invasive dental procedures is reported. A single dose of 180-200 micro g/kg was successfully used in three surgical removals of impacted teeth. Four doses of rFVIIa were required in another full mouth treatment of extraction, pulpotomy, filling and the stainless steel crowning of 13 teeth. The repeated dose of rFVIIa was given whenever the bleeding complication was visualized. It is cost-effective for preventing external bleeding. Additionally, an oral rinsing solution of tranexamic acid (25 mg/kg) was given three times a day for 7 days. In conclusion, rFVIIa has been shown to be an effective alternative to platelet concentrate in patients with Glanzmann thrombasthenia.

Plasma fibrinogen explains much of the difference in risk of coronary heart disease between France and Northern Ireland. The PRIME study

The incidence of coronary heart disease is higher in Northern Ireland than in France. These differences have not been adequately explained. We have investigated the associations of plasma fibrinogen concentration and factor VII activity with the incidence of coronary heart disease in a prospective cohort study involving 10600 men aged 50-59 living in four regions (Lille, Strasbourg, and Toulouse in France, Belfast in Northern Ireland). Baseline fibrinogen and factor VII were measured in 9489 men free of coronary heart disease at entry (7167 in France and 2322 in Northern Ireland). Over 5 years of follow-up, 161 participants developed myocardial infarction (MI) or coronary death (100 in France and 61 in Belfast) and 151 developed angina pectoris (94 in France and 57 in Belfast). The risk of future coronary events was 1.9 times higher in Belfast than in France (95% confidence interval: 1.5-2.4). Baseline mean levels of fibrinogen were significantly higher in Belfast than in France and they were higher in participants who experienced coronary events compared with those who did not in both countries. The age-adjusted relative risk of coronary heart disease associated with a rise of one standard deviation in fibrinogen level was 1.56 (95% confidence interval: 1.29-1.95, P<0.0001) in the whole cohort. This association remained significant after adjustment for other cardiovascular risk factors (relative risk:1.36; 95% confidence interval: 1.14-1.68; P<0.0001). There was no clear geographical variation in factor VII and no significant association between factor VII levels and the risk of coronary events was observed. Classic risk factors explained 25% of the excess risk of coronary heart disease in Belfast compared with France, while fibrinogen alone accounted for 30%. These findings add to the epidemiological evidence that elevated fibrinogen is a major risk factor for coronary heart disease.

Pharmacokinetics of coagulation factors: clinical relevance for patients with haemophilia

Haemophilia is a recessively inherited coagulation disorder, in which an X-chromosome mutation causes a deficiency of either coagulation factor VIII (FVIII) in haemophilia A, or factor IX (FIX) in haemophilia B. Intravenous administration of FVIII or FIX can be used to control a bleeding episode, to provide haemostasis during surgery or for long term prophylaxis of bleeding. In special cases, activated factor VII (FVIIa) may be used instead of FVIII or FIX. The aim of this work is to review the pharmacokinetics of FVIII, FIX and FVIIa and to give an outline of the use of pharmacokinetics to optimise the treatment of patients with haemophilia. The pharmacokinetics of FVIII are well characterised. The systemic clearance (CL) of FVIII is largely determined by the plasma level of von Willebrand factor (vWF), which protects FVIII from degradation. Typical average CL in patients with normal vWF levels is 3 ml/h/kg, with an apparent volume of distribution at steady state (Vss) that slightly exceeds the plasma volume of the patient, and the average elimination half-life (t1/2) is around 14 hours. There are still some discrepancies in the literature on the pharmacokinetics of FIX. The average CL of plasma-derived FIX seems to be 4 ml/h/kg, the Vss is 3 to 4 times the plasma volume and the elimination t1/2 often exceeds 30 hours. FVIIa has a much higher CL (average of 33 ml/h/kg), and a short terminal t1/2 (at 2 to 3 hours). The Vss is 2 to 3 times the plasma volume. Since the therapeutic levels of coagulation factors are well defined in most clinical situations, applied pharmacokinetics is an excellent tool to optimise therapy. Individual tailoring of administration in prophylaxis has been shown to considerably increase the cost effectiveness of the treatment. Dosage regimens for the treatment of bleeding episodes or for haemostasis during surgery are also designed using pharmacokinetic data, and the advantages of using a constant infusion instead of repeated bolus doses have been explored. The influence of antibodies (inhibitors) on the pharmacokinetics of FVIII and FIX is in part understood, and the doses of coagulation factor needed to treat a patient can tentatively be calculated from the antibody titre. In conclusion, therapeutic monitoring of coagulation factor levels and the use of clinical pharmacokinetics to aid therapy are well established in the treatment of patients with haemophilia.

Anticoagulation and the heart

Cardiovascular disease is associated with a heightened risk of thrombosis that can manifest as acute myocardial infarction, cardiac death, and stroke. Similarly, valvular heart disease (which alters blood-flow dynamics) and the insertion of prosthetic materials (which stimulates localized thrombosis on foreign surfaces) are associated with platelet aggregation and thrombin-mediated bioamplification of the coagulation cascade. Physiologic principles and pathobiologic mechanisms determine the preferred means either to prevent or attenuate both thrombosis and subsequent cardiovascular events. Anticoagulant therapy in hospital- and outpatient-based settings has appropriately assumed a central role in the prevention and treatment of thrombotic disorders of the cardiovascular system. Carefully-designed clinical trials will establish safe and effective antithrombotic therapies for wide-scale implementation.

Relationships between alcoholic beverages and cardiovascular risk factor levels in middle-aged men, the PRIME Study. Prospective Epidemiological Study of Myocardial Infarction Study

The relationships between alcoholic beverages and cardiovascular risk factors were assessed in 6730 men living in France or Northern Ireland. In France, all alcoholic beverages were significantly correlated with body mass index (BMI), systolic (SBP) and diastolic blood pressure (DBP), high density lipoprotein (HDL) parameters, PAI-1 and Factor VII, whereas only wine was negatively related with fibrinogen levels. After adjusting for center, age, BMI, educational level, smoking and marital status, wine had a lesser effect on blood pressure, triglyceride, apo B and LpE:B levels than beer. Wine was associated with lower fibrinogen levels and beer with higher PAI-1 activity levels independent of the amount of alcohol consumed. In Northern Ireland, wine was negatively correlated with BMI, triglycerides, LpE:B and fibrinogen, whereas beer was positively correlated with SBP and DBP, triglycerides, HDL, apoprotein A-I and fibrinogen. Multivariate analysis showed wine to be positively associated with HDL parameters, and negatively with fibrinogen levels. Wine was also associated with higher LpA-I levels and lower fibrinogen levels independent of the amount of alcohol consumed. We conclude that alcohol consumption is related to lipid, lipoprotein and haemostatic variables, but the magnitude of the relationships depends on the type of alcoholic beverage. Also, some effects might be related to non-alcoholic components.

Haemostasis in Relation to Dietary Fat as Estimated by Erythrocyte Fatty Acid Composition: The Prime Study

We investigated whether haemostatic variables were related with dietary fatty acid composition as estimated by the fatty acid content of erythrocytes. Subjects were a subsample (n=283) of the participants in the Prospective Epidemiological Study of Myocardial Infarction (PRIME) Study. Factor VII, fibrinogen, tissue-type plasminogen activator antigen (tPA-ag), plasminogen activator inhibitor type 1 (PAI-1), D-dimer and von Willebrand factor (vWf) were measured and the fatty acid composition was determined in the phospholipids of total erythrocytes by gas chromatography. Statistical analyses were performed using multiple linear regression analyses with adjustment for age, center and body mass index. tPA-ag was significantly related to the n-3 fatty acids derived from fish. This was reflected in an inverse association of all n-3 fatty acids combined with tPA-ag (beta=-0.37 ng/ml/%, 95% confidence intervals: -0.45, -0.29, P<.01). Positive and significant associations of D-dimer with arachidic and eicosamonoenoic acid were observed (P<.01). No relationships were found between fatty acids and fibrinogen, vWf, PAI-1 or factor VII. The results of this study suggest that consumption of n-3 fatty acids derived from fish may favourably influence tPA-ag.

Daily concentrations of air pollution and plasma fibrinogen in London

OBJECTIVES

The reason for the association between air pollution and risk of cardiovascular diseases is unknown. The hypothesis was examined that daily concentrations of air pollution are associated with daily concentrations of fibrinogen, a risk factor for cardiovascular disease.

METHODS

Data on concentrations of plasma fibrinogen for 4982 male and 2223 female office workers, collected in a cross sectional survey in London between September 1991 and May 1993, were combined with data on concentrations of air pollution during the day of blood sampling and during the 3 preceding days.

RESULTS

After adjustment for weather and other confounding factors, an increase in the 24 hour mean NO(2) during the previous day from the 10th to the 90th percentile (61.7 microg/m(3)) was associated with a 1.5% (95% confidence interval (95% CI) 0.4% to 2.5%) higher fibrinogen concentration. The respective increase for CO (1.6 mg/m(3)) was 1.5% (95% CI 0.5%, 2.5%). These associations tended to be stronger in the warm season (April to September). Significant associations were found for black smoke and particulate matter of diameter 10 microm (PM(10)) only in the warm season. No association with fibrinogen was found for SO(2) or ozone.

CONCLUSIONS

The short term association between air pollution, possibly from traffic, and risk of cardiovascular events may be at least partly mediated through increased concentrations of plasma fibrinogen, possibly due to an inflammatory reaction caused by air pollution.

Plasma fibrinogen and factor VII concentrations in adults after prenatal exposure to famine

To assess the effect of maternal malnutrition during different stages of gestation on plasma concentrations of fibrinogen and factor VII, we investigated 725 people, aged 50 years, born around the time of the Dutch famine 1944-5. After adjustment for sex, plasma fibrinogen concentrations differed by -0.01 g/l (95% confidence interval, -0.14-0.11) in those exposed in late gestation, by -0.03 g/l (-0.16-0.11) in those exposed in mid gestation, and by 0.13 g/l (-0.03-0.30) in those exposed in early gestation, compared with non-exposed people (those born before and those conceived after the famine pooled together). Plasma factor VII concentrations differed by 0.4% (-5.4% to 6.6%) in those exposed to famine in late gestation, by 1.5% (-4.6% to 8.1%) in those exposed in mid gestation. and by -11.8% (-18.4 to -4.8%) in those exposed in early gestation, compared with nonexposed people. Size at birth was not associated with plasma concentrations of fibrinogen or factor VII. Our finding that factor VII concentrations were significantly lower in people whose mothers had been exposed to famine in early pregnancy suggests that liver function may be affected by undernutrition in early gestation.

Recombinant activated factor VII in children with acute bleeding resulting from liver failure and disseminated intravascular coagulation

Recombinant activated factor VII (rFVIIa) was given to three children with acute bleeding resulting from liver failure and disseminated intravascular coagulation. Cases I and II (girls aged 3 years and 6 years, respectively) were diagnosed with Dengue hemorrhagic fever and prolonged shock. Case III, a boy aged 9 months, underwent left lobe hepatectomy for a hepatoblastoma, during which 60% of his liver was removed. This case was complicated by myoglobinuria, liver and renal impairment and early disseminated intravascular coagulation. All three patients exhibited active bleeding. Cases I and II received rFVIIa combined with other blood component replacement, while Case III received rFVIIa as the only hemostatic agent. A bolus of 40-180 microg/kg b.w. was administered followed by 16.5-33 microg/kg b.w. per h continuous infusion. As a result, bleeding was controlled, the prothrombin time was shortened and FVII clotting activity was significantly increased. In conclusion, rFVIIa has shown some efficacy in controlling acute bleeding in children with liver failure and disseminated intravascular coagulation.

Controlling acute bleeding episodes with recombinant factor VIIa in haemophiliacs with inhibitor: continuous infusion and bolus injection

The efficacy of recombinant activated factor VII (rFVIIa, NovoSeven) in five Haemophiliacs (four Haemophilia A, one Haemophilia B), with high inhibitors ranging from 70 to 1900 Bethesda units, was evaluated. The treatment regimen was divided into two groups: group I, continuous infusion of 16.5 microg h-1 kg-1 body weight (bw) after the initial bolus of 90 microg kg-1 bw in three episodes of severe bleeding and group II, bolus injection 80-150 microg kg-1 bw every 3 hours for a maximum of four doses in six haemarthroses. The bleeding was effectively controlled within 1 to 48 h in five of nine bleeding episodes. One patient in group I, who had active arterial bleeding requiring sutures, had an ineffective response and three patients in group II had partially effective responses because the rFVIIa was given after the onset of bleeding at 36, 44 and 72 h, respectively. The prothrombin time was shortened and the FVII:C levels were successfully achieved at approximately 10 U mL-1. The continuous infusion reduced the total dose of rFVIIa by 50%. Recurrent bleeding episodes were found in three patients; two occurred at the same site after ceasing rFVIIa for 51 h and while receiving rFVIIa at 144 h and one occurred at a new site after ceasing rFVIIa for 12 h. Our experience would suggest that rFVIIa is effective in controlling acute bleeding episodes in Haemophiliacs with high inhibitors either by continuous infusion or bolus injection.

Are risk factors for atherothrombotic disease associated with back pain sickness absence? The Whitehall II Study

STUDY OBJECTIVE

To explore the previously stated hypothesis that risk factors for atherothrombotic disease are associated with back pain.

DESIGN

Prospective (mean of four years of follow up) and retrospective analyses using two main outcome measures: (a) short (< or = 7 days) and long (> 7 days) spells of sickness absence because of back pain reported separately in men and women; (b) consistency of effect across the resulting four duration of spell and sex cells.

SETTING

14 civil service departments in London.

PARTICIPANTS

3506 male and 1380 female white office-based civil servants, aged 35-55 years at baseline.

MAIN RESULTS

In age adjusted models, low apo AI was associated with back pain across all four duration-sex cells and smoking was associated across three cells. Six factors were associated with back pain in two cells: low exercise and high BMI, waist-hip ratio, triglycerides, insulin and Lp(a). On full adjustment (for age, BMI, employment grade and back pain at baseline), each of these factors retained a statistically significant effect in at least one duration-sex cell. Triglycerides were associated with short and long spells of sickness absence because of back pain in men in fully adjusted models with rate ratios (95% confidence intervals) of 1.53 (1.1, 2.1) and 1.75 (1.0, 3.2) respectively. There was little or no evidence of association in age adjusted models with: fibrinogen, glucose tolerance, total cholesterol, apoB, hypertension, factor VII, von Willebrand factor, electrocardiographic evidence of coronary heart disease and reported angina.

CONCLUSIONS

In this population of office workers, only modest support was found for an atherothrombotic component to back pain sickness absence. However, the young age of participants at baseline and the lack of distinction between different types of back pain are likely to bias the findings toward null. Further research is required to ascertain whether a population sub-group of atherothrombotic back pain can be identified.

Relationship of blood coagulation and fibrinolysis to vital exhaustion

OBJECTIVE

Acute physical and psychological stressors affect blood coagulation and fibrinolysis, but little is known about hemostatic factors associated with chronic psychological stress. Prolonged psychological stress may end in a state of vital exhaustion, which has been shown to be a risk factor for first myocardial infarction and recurrent events after coronary angioplasty. The present study tested the hypothesis that vital exhaustion resulting from chronic psychological stress is associated with impaired fibrinolytic capacity and increased coagulation factors.

METHODS

On the basis of a validated questionnaire and subsequent structured interview, a well-defined group of otherwise healthy exhausted men was recruited (N = 15) and compared with age-matched not-exhausted controls (N = 15). Fibrinolytic measures included tissue plasminogen activator (TPA) antigen and plasminogen activator inhibitor (PAI-1) activity, and as coagulation factors we examined factors VIIc, factor VIIIc, and fibrinogen. Control variables were: blood pressure, smoking status, triglycerides, cholesterol, and standard hematological measures. Samples were collected twice to correct for intraindividual fluctuations. Statistical analyses were performed using 2 x 2 mixed model analysis of variance with subsequent univariate testing.

RESULTS

Vital exhaustion was associated with significantly elevated levels of PAI-1 activity (p = .023). The higher PAI-1 activity in exhausted subjects (median = 13.0 U/ml vs. 6.0 U/ml) was not accounted for by smoking status or serum lipids. No significant differences were observed in TPA antigen, factor VIIc, factor VIIIc, and fibrinogen. The groups did not differ in blood pressure, smoking status, triglycerides, cholesterol, or standard hematological measures.

CONCLUSION

These data suggest a reduced fibrinolytic capacity in exhausted individuals. Therefore, the relationship between vital exhaustion and risk of myocardial infarction may be mediated in part by an imbalance between blood coagulation and fibrinolysis.

The effect of hormone replacement therapy of the age-related rise of factor VIIc, and its activity state

Although hormone replacement therapy (HRT) appears to protect women from ischaemic heart disease (IHD), its use is associated with increased factor clotting activity (VIIc), an independent risk factor for IHD. The nature of this factor VII rise was therefore examined in a cross-sectional study of 279 women aged between 40 and 65 years. Ninety-four were pre-menopausal, 44 were post-menopausal and taking HRT, whilst 141 were post-menopausal non-users. For those women on oestrogen-only HRT, the mean factor VIIc was 144%, compared to 130% for post-menopausal non-users, and 116% for those on combined HRT. These differences were significant (p = 0.01). Oestrogen-only users also had significantly higher mean levels of factor VIIa (3.3 ng/ml) compared to non-users (2.2 ng/ml) and those on oestrogen-progestogen HRT (2.2 ng/ml-p = 0.015). In contrast for factor VII antigen the mean values of the three groups were similar. Analysis of the age-regression slopes showed a significant age-related rise in factor VIIc of 1.2% per annum (p < 0.01) for post-menopausal non-users. There was a similar increase in factor VII antigen (2.1%) but no rise in factor VIIa. For all HRT users there was no change with age for any of the factor VII measures. Thus the age-related rise in factor VIIc appears to be due to an increase in factor VII zymogen alone, and taking HRT seems to abolish such a rise. In contrast, the increased factor VIIc seen with oestrogen-only HRT appears to be secondary to factor VII activation.

Population correlates of coagulation factor VII. Importance of age, sex, and menopausal status as determinants of activated factor VII

Factor VII coagulant activity (FVIIc) has been found to be related to cardiovascular risk factors and may be an independent predictor of coronary heart disease (CHD). Whether these associations are due to changes in FVII activation rather than FVII concentration remain unclear. Therefore, we investigated the relationships between activated factor VII (FVIIa) and CHD risk factors in healthy subjects (336 men and 348 women) aged 25 to 64 years. In addition to direct quantitation of FVIIa by use of a recombinant, truncated tissue factor, FVIIc and factor VII antigen (FVII:Ag) levels were measured by standard procedures. There were highly significant correlations between the three techniques of FVII assay (r > + .55). Plasma FVIIc and FVIIa levels increased with age in both sexes, but the rate of rise was significantly greater in women than men. At younger ages, mean values of FVIIc and FVIIa were significantly lower in women than men, whereas at older ages the reverse was observed. After adjustment for age, postmenopausal women had significantly higher mean levels of FVIIc and FVIIa than did premenopausal women. Hormone replacement therapy significantly reversed the rise in FVIIc in postmenopausal women, and a similar trend in FVIIa was also observed. Age-, sex-, and menopause-related changes in FVIIc were partly explained by a higher proportion of fully active FVII molecules, as indicated by significant differences in the FVIIa-to-FVII:Ag ratio. Oral contraceptive use was associated with high FVIIc levels, and this effect was mainly due to an increase in FVII:Ag. Levels of FVIIa were positively correlated with serum cholesterol concentrations in both sexes. There were no strong associations between FVIIa levels and other CHD risk factors, including smoking habits, alcohol consumption, blood pressure, obesity, glucose, triglycerides, and serum lipoprotein(a) concentrations. Multiple regression analysis showed independent effects of age and cholesterol levels on FVIIa in men, whereas age and menopausal status were the main predictors of FVIIa in women. Our results show that FVII activation is associated with CHD risk factors. These findings are consistent with a possible role for FVII in the pathogenesis of CHD. Furthermore, our data suggest that the dramatic rise in CHD incidence in postmenopausal women as well as the cardioprotective effect of estrogen may be mediated through FVII and blood coagulation.

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.

Activation of factors XII and VII induced in citrated plasma in the presence of contact surface

Activated factor XII (XIIa), activated factor VII (VIIa) and factor VII coagulant activity (VIIc) were determined in non-treated and in treated (cold-incubated) citrated plasmas from women in late pregnancy and from norma volunteers. All three activities were higher in the non-treated plasmas from women in late pregnancy than from normal subjects. The incubation of citrated plasmas from women in late pregnancy, on ice for 24 hours, resulted in a many-fold increase of factor XIIa activity, factor VIIa levels and VIIc. The dilution of these plasmas resulted in a sharp decrease of all three activities in the post-incubation mixture, so that in the plasmas diluted 2:1 with buffer all three activities were similar to those in fresh plasmas. Similar incubations of diluted plasmas (1:1) from normal volunteers resulted in no increase of factor XIIa activity, factor VIIa levels and VIIc. However, the presence in the incubation mixture of micellar stearate resulted in a stearate concentration-dependent increase of all three activities in treated plasmas. Levels of factor XIIa activity and factor VIIa in the treated plasmas from both groups of subjects were highly correlated (r = 0.987; p < 0.001). There was also a highly significant correlation between VIIc and factor VIIa levels (0.989; p < 0.001). These results demonstrate that the in vitro increase in factor VIIa levels is due to the activation of the contact system of coagulation and is dependent on the potency of the contact surface. Moreover, VIIc over a wide range of values, observed in the present experiments, can provide an accurate measure of factor VIIa concentration.

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)

Insulin resistance, lipoproteins, body fat and hemostasis in nonobese men with angina and a normal or abnormal coronary angiogram

OBJECTIVES

The aim of this study was to compare metabolic risk factors in men with anginal chest pain and a normal or abnormal coronary angiogram with those in healthy men.

BACKGROUND

Risk factors for coronary heart disease, including lipoprotein abnormalities, hypertension and adiposity, may be metabolically interlinked, with insulin resistance and hyperinsulinemia being pivotal to these disturbances.

METHODS

Glucose and insulin metabolism, lipids and lipoproteins, hemostasis, blood pressure and body fat distribution were measured in 77 nonobese middle-aged men who had anginal chest pain (39 with an abnormal coronary angiogram and 38 with no detectable angiographic abnormality) and were compared with those of 40 healthy men of similar age and body mass index.

RESULTS

Patients with chest pain had higher insulin responses to an intravenous glucose challenge, lower insulin sensitivity, lower high density lipoprotein (HDL) and subfraction 2 cholesterol, lower apolipoprotein AI, higher triglycerides, greater android fat and higher systolic blood pressure at rest compared with levels in healthy control subjects (p < 0.05). Those with an abnormal coronary angiogram had lower tissue plasminogen activator levels, higher plasminogen activator inhibitor 1 levels and more android fat than did those with a normal angiogram (p < 0.05). Insulin sensitivity correlated positively with HDL (p < 0.05) and subfraction 2 (p < 0.001) cholesterol and negatively with triglycerides (p < 0.01), android fat proportion (p < 0.01) and systolic blood pressure (p < 0.05), whereas insulin response showed converse correlations.

CONCLUSIONS

These findings provide new evidence of the central role of insulin resistance and hyperinsulinemia in the development of risk factors associated with coronary heart disease.

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)

Gender and employment grade differences in blood cholesterol, apolipoproteins and haemostatic factors in the Whitehall II study

In the first Whitehall study, plasma cholesterol was a strong predictor of coronary heart disease (CHD) but it showed a positive association with grade of employment: the higher the grade the higher the level. Because it could not explain the higher rate of CHD in lower employment grades, further investigation of biochemical CHD risk factors has been conducted with data from the baseline examination of the Whitehall II cohort in 1985-88. These data also allow investigation of gender differences and the effect of menopause. Serum cholesterol (6860 men and 3374 women) and apolipoproteins A-I and B (apo AI and apo B) were measured in those aged 35-55 working in the London offices of twenty Civil Service departments. Plasma fibrinogen and factor VII were determined in 45-55 year olds. The apo B/apo AI ratio (95% confidence interval) after age adjustment is lowest in premenopausal women: 0.557 (0.549-0.565), intermediate in postmenopausal women: 0.601 (0.589-0.613) and highest in men: 0.703 (0.698-0.709). After age adjustment fibrinogen is higher in postmenopausal (2.90 (2.85-2.95) g/l) than in premenopausal women (2.78 (2.71-2.84) g/l), who have higher levels than men (2.64 (2.62-2.67) g/l). A positive association with employment grade is seen for apo AI and a negative association is seen for fibrinogen, apo B (women only) and the apo B/apo AI ratio, after age adjustment. These patterns are consistent with the higher rates of CHD in lower grades. Cholesterol and factor VII show no gradient with our sensitive measure of social position. After adjusting for the effects of smoking rates, alcohol consumption, exercise and dietary pattern, as well as age, ethnicity, body mass index and report of symptoms, the regression coefficient for apo AI on employment grade is reduced by 43% in men and 70% in women. Corresponding reductions for fibrinogen are 53% and 65%. These attenuations suggest that a considerable part of the social gradients in apo AI and fibrinogen are explained by variations in health related behaviours. The remaining gradients may represent effects independent of these behaviours.

Relation of hemostatic risk factors to other risk factors for coronary heart disease and to sex hormones in men

The present study was carried out to explore the possible relation of plasma plasminogen activator inhibitor-1 (PAI-1), fibrinogen, and factor VII levels to other risk factors for coronary heart disease (CHD) and to serum sex hormone levels. The study group comprised 48 apparently healthy men. To avoid the confounding factor of obesity, correlations were determined in the 30 men in this group with a body mass index (BMI) < 26.4, after controlling for age. PAI-1 correlated with testosterone, estradiol/testosterone, and free testosterone/testosterone (FT/T), and fibrinogen correlated with FT/T. All three hemostatic factors correlated with glucose and with the ratio of cholesterol/high density lipoprotein cholesterol, while PAI-1 correlated with diastolic blood pressure. To test the effect of obesity, correlations were determined in the entire group of 48 men, which included 18 subjects with a BMI > 26.4. All three hemostatic factors correlated with BMI in this group after controlling for age; however, on controlling for testosterone, only PAI-1 correlated with BMI. Fibrinogen correlated with age in both groups after controlling for testosterone or BMI. These correlations support the hypothesis that PAI-1, fibrinogen, and factor VII are related to other risk factors for CHD and that an alteration in the sex hormone milieu may be the underlying factor linking them.

Type 2 (non-insulin-dependent) diabetes mellitus, hypertension and hyperlipidaemia (syndrome X): relation to reduced fetal growth

Two follow-up studies were carried out to determine whether lower birthweight is related to the occurrence of syndrome X-Type 2 (non-insulin-dependent) diabetes mellitus, hypertension and hyperlipidaemia. The first study included 407 men born in Hertfordshire, England between 1920 and 1930 whose weights at birth and at 1 year of age had been recorded by health visitors. The second study included 266 men and women born in Preston, UK, between 1935 and 1943 whose size at birth had been measured in detail. The prevalence of syndrome X fell progressively in both men and women, from those who had the lowest to those who had the highest birthweights. Of 64-year-old men whose birthweights were 2.95 kg (6.5 pounds) or less, 22% had syndrome X. Their risk of developing syndrome X was more than 10 times greater than that of men whose birthweights were more than 4.31 kg (9.5 pounds). The association between syndrome X and low birthweight was independent of duration of gestation and of possible confounding variables including cigarette smoking, alcohol consumption and social class currently or at birth. In addition to low birthweight, subjects with syndrome X had small head circumference and low ponderal index at birth, and low weight and below-average dental eruption at 1 year of age. It is concluded that Type 2 diabetes and hypertension have a common origin in sub-optimal development in utero, and that syndrome X should perhaps be re-named "the small-baby syndrome".

Lipolysis of triglyceride-rich lipoproteins activates coagulant factor XII: a study in familial lipoprotein-lipase deficiency

A high factor VII coagulant activity (VIIc), a marker of increased risk of coronary heart disease, is frequently found in types IIb and IV hyperlipidaemia, but its cause is not fully understood. Factor VII can be activated by factor XIIa, generated from factor XII upon activation of the contact system of coagulation. Ten patients with familial lipoprotein-lipase (LPL) deficiency and 10 healthy control subjects were therefore compared to explore the hypothesis that high concentrations of unesterified fatty acids (UFA), released from triglyceride-rich lipoproteins by LPL, are a source of factor XII activation and hence the increased VIIc that is observed post-prandially and in non-LPL-deficient hypertriglyceridaemic states. Mean plasma cholesterol and triglyceride concentrations were, respectively, 1.5- and 19-fold higher in the patients than controls, due to increases in very-low-density lipoproteins and chylomicrons. The concentration and composition of plasma UFA were similar in both groups. In conformity with the hypothesis, VIIc was not increased in the LPL-deficient group, despite their massive hypertriglyceridaemia. Furthermore, when the patients' plasma was treated with LPL, factor XII was activated promptly and substantially, whereas no similar effect was observed in the controls. These results suggest that high concentrations of circulating triglyceride-rich lipoproteins will increase VIIc in the presence of LPL.

Environmental influences on hemostasis and thrombosis. Diet and smoking

High levels of factor VII coagulant activity (VIIc) and fibrinogen concentration are independently associated with an increased risk of acute coronary heart disease in middle-aged men. Studies have, therefore, been undertaken to determine the responsiveness of these hemostatic factors to changes in diet and smoking habit. Plasma VIIc increases acutely with an increase in total fat intake, but fibrinogen is unaffected. In the general community, men who have a high total fat intake for their body size tend to have a high VIIc level. Changes in the dietary ratio of saturated to polyunsaturated fat of up to 14 days' duration have no effect on factor VIIc or fibrinogen (there are conflicting reports on the influence of dietary very-long-chain polyunsaturated fatty acids on fibrinogen concentration). Cigarette smokers have a higher fibrinogen concentration than do nonsmokers, but their levels slowly revert toward those of nonsmokers when the habit is relinquished.

Relation of fetal and infant growth to plasma fibrinogen and factor VII concentrations in adult life

OBJECTIVE

To determine whether reduced fetal and infant growth are associated with higher plasma fibrinogen and factor VII concentrations in adult life.

DESIGN

Follow up study of men born during 1920-30 whose weights at birth and at 1 year had been recorded by health visitors, and men born during 1935-43 whose size at birth had been measured in detail.

SETTING

Hertfordshire and Preston, England.

SUBJECTS

591 men born in east Hertfordshire who still lived there and 148 men born in Preston who still lived in or close to the city.

MAIN OUTCOME MEASURES

Plasma fibrinogen and factor VII concentrations.

RESULTS

Among men in Hertfordshire mean plasma fibrinogen and factor VII concentrations fell with increasing weight at 1 year (from 3.21 g/l in men of less than or equal to 18 lb to 2.93 g/l in men greater than or equal to 27 lb and from 122% of standard to 103%; p less than 0.001, p less than 0.005 respectively). The trends were independent of cigarette smoking, alcohol consumption, body mass index, and social class. Neither plasma fibrinogen nor factor VII concentration was related to birth weight. In men in Preston, however, fibrinogen concentration fell progressively as the ratio of placental weight to birth weight decreased (p = 0.01).

CONCLUSIONS

Reduced growth in fetal life and infancy is strongly related to high plasma concentrations of the haemostatic factors fibrinogen and factor VII. This may be a persisting response to impaired liver development during a critical early period.

Long-term use of depot-norethisterone enanthate: effect on blood coagulation factors and menstrual bleeding patterns

Fifty-six women using depot-norethisterone enanthate injections for contraception for 2 years or more were compared with a control group of 48 women not using hormonal contraception. No significant difference was found between the study group and controls for Factors VIIc and Antithrombin III. Factor Xc was reduced in women who had used the injections for over two but less than five years [controls: mean 90.3% SD31.2 vs users for 2-5 yr: 78.7% SD17.1, 95%CI difference in means -0.3, -22.9]. In the group using Net-En for five years or more, Factor Xc was significantly higher than in the control group, but only by 14% of the mean control value [users for over 5 yr: 103.2% SD15.2, 95%CI difference in means 3.1, 22.7]. Haemoglobin levels, red cell count and packed cell volume were higher in those using the injections than in the control group. Changes in the platelet count were not statistically significant. Twenty-three women using the injection agreed to keep menstrual diaries. Of these, 20 experienced amenorrhoea for more than two consecutive injection intervals (112 days). It is concluded that long-term use of norethisterone enanthate is not associated with any markedly deleterious effects on Factor VIIc, Xc, or antithrombin III or haemoglobin levels. Amenorrhoea of 4 months or more can be expected after two years of continuous use.

Plasma factor VII is activated by postprandial triglyceridaemia, irrespective of dietary fat composition

Nine adults took two 7-day diets of standardised energy and total fat content, but with a dietary polyunsaturated/saturated fat ratio of less than 0.3 and greater than 3.0 respectively, while adhering to their daily routine. Blood was drawn on 6 occasions between 09.00 and 22.45 h on the final day of each dietary period for factor VII activity (VIIc), factor VII antigen (VIIag) and lipoprotein lipid concentrations. Diurnal variation was described for each variable in terms of its deviation from the individual's daily mean value at each time point across the day. Plasma triglyceride remained low until after the midday meal, whereafter a marked rise was sustained into the later evening. Plasma VIIc declined until early afternoon, but showed a marked rise in the late afternoon. Plasma VIIag showed no significant diurnal variation. Changes in plasma triglyceride concentration during the day were related positively to changes in VIIc about 160 min later, but not to VIIc at other time points. This effect of postprandial triglyceridaemia on VIIc persisted after allowance for the effect of VIIag on VIIc. Dietary fat composition did not influence VIIc or VIIag. The results suggested an acute but evanescent effect of triglyceride-rich lipoproteins on the reactivity of factor VII, irrespective of their lipid core composition.

Fibrinogen, factor VII clotting activity and coronary artery disease severity

To asses the relationship between fibrinogen, factor VII coagulant (VIIc) activity and extent of coronary artery disease, we studied 43 white males shown to have greater than 50% stenosis of at least one major coronary artery. Thirty six had a definite history of myocardial infarction at least 3 months earlier and were classified as having 1, 2 or 3 vessel disease while 7 had 2 or 3 vessel disease, but no prior infarction. Groups were similar with regard to age, body mass index and blood pressure. In those with documented prior infarction, there was a significant relationship between the extent of atheroma and coagulation variables factor VIIc and fibrinogen. However, given a similar degree of atheroma, patients with prior infarction had significantly higher levels of factor VIIc activity compared with patients without such a history. These results corroborate those from prospective studies confirming a significant role for the coagulation system in the clinical manifestation of coronary artery disease.

Reduction of factor VII coagulant activity (VIIC), a risk factor for ischaemic heart disease, by fixed dose warfarin: a double blind crossover study

An increase in factor VII coagulant activity is known to be an important risk factor for ischaemic heart disease. Four hundred and eight healthy male Post Office workers were screened in an occupational survey. Sixty eight (16.5%) of these had values of factor VII coagulant activity greater than 1.0 SD above the age related mean. A randomised double-blind crossover study was undertaken to investigate the effect of a fixed daily minidose of warfarin (1 mg) on the high activities of factor VII in these men. Forty two agreed to enter the study and 40 completed it. Their mean factor VII coagulant activity before warfarin treatment was 135.9%. Treatment with a fixed minidose of warfarin significantly reduced factor VII coagulant activity to 124.6%; there was no change on placebo. The prothrombin time was also significantly prolonged on active treatment although all the results remained within the normal range. These findings suggested a fixed minidose warfarin regime might be useful in the primary prevention of ischaemic heart disease by reducing high activities of factor VII.

Microalbuminuria and cardiovascular risk factors in type 2 diabetes mellitus

Prospective studies have shown that increased urinary albumin excretion is a risk factor for cardiovascular morbidity and mortality in patients with Type 2 diabetes mellitus, but the nature of the association remains unknown. Eighty-five patients aged less than 65 years and not treated with insulin were studied. The overnight albumin excretion rate (AER) was measured in each patient and analysed in relation to several putative risk factors for cardiovascular disease. AER was used both as a continuous variable and after dividing patients into high-risk (AER greater than or equal to 10 micrograms min-1) and low-risk (AER less than 10 micrograms min-1) groups. By both methods of analysis AER was significantly correlated with both seated and supine diastolic blood pressure levels and with resting heart rate. Body mass index and waist-hip ratio appeared higher and HDL-cholesterol lower in the at-risk group, but differences were not statistically significant. The level of Factor VII was not significantly lower in the at-risk group. Little of the cardiovascular risk associated with raised AER can be attributed to associations with conventional risk factors.