Factor VII Antigen Levels Research Articles

Reduced Thrombus Formation in Native Blood of Homozygous Factor VII-Deficient Patients at High Arterial Wall Shear Rate

Inhibition of thrombin formation in flowing native blood reduces thrombus formation on subendothelium, dacron, or collagen fibrils at arterial wall shear rates of 450 to 650 s-1. In the present study, we have investigated the role of low levels of factor VII (FVII) in thrombus formation on collagen fibrils at arterial wall shear rates of 650 s-1 (coronary arteries), 2,600 s-1 (mildly stenosed arteries), and 10,510 s-1 (severely stenosed arteries) in parallel-plate perfusion chambers. In the perfusion chamber with the highest wall shear rate, thrombus formation took place at the apex of an eccentric stenosis, which reduced the cross-sectional area of the blood flow channel by 80%, thus simulating thrombus formation at an atherosclerotic plaque rupture. Native blood from 21 healthy volunteers and 12 homozygous FVII-deficient patients was drawn by a pump directly from an antecubital vein over a surface of fibrillar collagen positioned in the respective perfusion chambers. The patients had FVII coagulant activities ranging from 1.3% to 4.5% and FVII antigen levels of 16% to 23% of normal. Immunoaffinity purification of the patients' FVII followed by electrophoresis (sodium dodecyl sulfate-polyacrylamide gel electrophoresis [SDS-PAGE]) and immunoblotting showed a protein with similar molecular mass as normal FVII. In the perfusion studies, a reduction in thrombus volume of 54% of normal (P < .007) at 10,510 s-1 was observed. The deposition of fibrin on the thrombogenic surface and the plasma level of fibrinopeptide A (FPA) in blood samples collected distal to the perfusion chamber were concomitantly reduced (P < .002 and P < .04, respectively). The plasma FPA level was also reduced at 2,600 s-1 (P < .04), but not at 650 s-1. However, at the lower shear conditions, the thrombus volume and the fibrin deposition were within the ranges observed in normal blood. The platelet-collagen adhesion was not affected at any of the three shear conditions. Thus, low plasma levels of FVII result in significantly less formation of thrombin and fibrin in and around growing platelet masses at high shear condition. This may weaken the thrombus stability and reduce platelet recruitment, thereby lowering thrombus volume. In support of this theory, one patient with afibrinogenemia had an 83% reduction in thrombus volume at this high shear condition.

Reduced thrombus formation in native blood of homozygous factor VII- deficient patients at high arterial wall shear rate

Inhibition of thrombin formation in flowing native blood reduces thrombus formation on subendothelium, dacron, or collagen fibrils at arterial wall shear rates of 450 to 650 s-1. In the present study, we have investigated the role of low levels of factor VII (FVII) in thrombus formation on collagen fibrils at arterial wall shear rates of 650 s-1 (coronary arteries), 2,600 s-1 (mildly stenosed arteries), and 10,510 s-1 (severely stenosed arteries) in parallel-plate perfusion chambers. In the perfusion chamber with the highest wall shear rate, thrombus formation took place at the apex of an eccentric stenosis, which reduced the cross-sectional area of the blood flow channel by 80%, thus simulating thrombus formation at an atherosclerotic plaque rupture. Native blood from 21 healthy volunteers and 12 homozygous FVII- deficient patients was drawn by a pump directly from an antecubital vein over a surface of fibrillar collagen positioned in the respective perfusion chambers. The patients had FVII coagulant activities ranging from 1.3% to 4.5% and FVII antigen levels of 16% to 23% of normal. Immunoaffinity purification of the patients' FVII followed by electrophoresis (sodium dodecyl sulfate-polyacrylamide gel electrophoresis [SDS-PAGE]) and immunoblotting showed a protein with similar molecular mass as normal FVII. In the perfusion studies, a reduction in thrombus volume of 54% of normal (P &lt; .007) at 10,510 s-1 was observed. The deposition of fibrin on the thrombogenic surface and the plasma level of fibrinopeptide A (FPA) in blood samples collected distal to the perfusion chamber were concomitantly reduced (P &lt; .002 and P &lt; .04, respectively). The plasma FPA level was also reduced at 2,600 s-1 (P &lt; .04), but not at 650 s-1. However, at the lower shear conditions, the thrombus volume and the fibrin deposition were within the ranges observed in normal blood. The platelet-collagen adhesion was not affected at any of the three shear conditions. Thus, low plasma levels of FVII result in significantly less formation of thrombin and fibrin in and around growing platelet masses at high shear condition. This may weaken the thrombus stability and reduce platelet recruitment, thereby lowering thrombus volume. In support of this theory, one patient with afibrinogenemia had an 83% reduction in thrombus volume at this high shear condition.

Haemostatic factors and lipoprotein (a) in three geographical areas in Finland: the Finrisk Haemostasis Study.

An increasing volume of evidence suggests that haemostatic factors play a role in the risk of coronary heart disease. It is not known, however, whether between-population differences in haemostatic factors correspond with the differences in mortality related to coronary heart disease. We examined this question in Finland, where, in North Karelia (in the eastern part of the country), the mortality from coronary heart disease is 1.5-1.7 times higher than that in southwestern areas. A random sample of 3000 people aged 45-64 years was drawn from the population registers of North Karelia, of the area surrounding Turku and Loimaa in southwestern Finland and of the Helsinki area in southern Finland. Of the 3000 people approached, 79.6% took part in the study. differences in coronary heart disease mortality and morbidity. Factor-VII coagulant activity was significantly higher in North Karelia than in the other areas (P = 0.0008). The fibrinogen level was also higher in North Karelia, although the difference was significant only among non-smokers (P = 0.02). Levels of factor-VII antigen, plasminogen and lipoprotein (a) did not differ between the areas. Within North Karelia, the levels of both factor-VII coagulant activity, and factor-VII antigen were higher in rural areas than in urban areas. Levels of factor-VII coagulant activity, factor-VII antigen and plasminogen were higher in women than in men and increased with age in women but not in men. The fibrinogen level increased with age in both sexes. These baseline findings of the Finrisk Haemostasis Study demonstrate that the geographical differences in levels of factor-VII coagulant activity and fibrinogen in Finland are consistent with the population

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)

Factor VII Antigen Levels in a Healthy Blood Donor Population

We determined factor VII antigen (FVIIag) levels in 705 healthy blood donors ranging in age from 17 to 79 years using a two-site solid-phase enzyme immunoassay developed in our laboratory. The mean (+/- SD) FVIIag level for the total population was 102 +/- 31%. FVIIag levels for men (n = 375) and women (n = 330) were 101 +/- 28% and 103 +/- 33%, respectively. A significant increase in FVIIag was observed with age in both men (r = 0.25, p < 0.0001) and women (r = 0.35, p < 0.0001). FVIIag levels were significantly higher in women > 60 years when compared to men (median women: 125%; median men: 111%; p < 0.05). On a subset of the study group (n = 45), FVIIag levels were correlated to total cholesterol (r = 0.27, p = 0.08) and triglyceride (r = 0.41, p < 0.01). Assuming the commonly used reference interval of 60-140% for FVII, the frequencies of FVIIag values for < 60% and > 140% using our assay were 2.1% and 9.2%, respectively. Gender and age-related differences in FVIIag levels must be considered in a reference interval. We further suggest that assay-specific reference ranges be established, which may include values outside the commonly used values of 60-140%.

Factor VII Mie: Homozygous Asymptomatic Type I Deficiency Caused by an Amino Acid Substitution of His (CAC) for Arg(247) (CGC) in the Catalytic Domain

We found hereditary factor VII deficiency in a clinically asymptomatic family, and characterized their factor VII gene and the abnormal molecule using recombinant DNA techniques. The propositus was a 45-year-old woman who was noted to have a prolonged prothrombin time. The level of factor VII antigen of the patient was 25.9% of that of normal individuals and the level of factor VII activity was 28% and 24%, when tested using rabbit brain tissue factor and human placental tissue factor in a one-stage clotting assay, respectively. Two of her sisters had almost the same reduced levels of factor VII antigen and activity, and her parents who are first cousins, a son, a daughter and a niece had moderately reduced leves of both factor VII activity and antigen. To identify the mutation site, all the coding exons and exon-intron boundaries of the factor VII gene of the propositus were amplified using the polymerase chain reaction (PCR), then subcloned and sequenced. One missense mutation (G to A) was identified in exon VII of the gene resulting in an amino acid substitution of His(CAC) for Arg(247)(CGC) in the gene product. PCR using a mutagenic primer to introduce a new ApaL I site into the mutant allele of the patient's factor VII gene revealed that this allele was inherited in the affected individuals in the pedigree. Transient expression assays using BHK cells transfected with an expression vector containing the mutant factor VII cDNA suggested that this mutation leads to factor VII deficiency by impairing secretion of the mutated factor VII.(ABSTRACT TRUNCATED AT 250 WORDS)

Relationship of Tissue Factor Pathway Inhibitor Activity to Plasma Lipoproteins and Myocardial Infarction at a Young Age

Tissue factor pathway inhibitor (TFPI) activity was quantified in two cohorts of young male post-infarction patients and in population-based control subjects to explore the relationships between TFPI activity and plasma lipoproteins and to address the issue of coordinate regulation of factor VII and TFPI in hyperlipidaemia and premature coronary heart disease (CHD). Participants were investigated in the fasting state and after an oral fat load. Basal TFPI activity and factor VII antigen (VIIag) levels were found to be increased in the patients (TFPI activity 1.25 +/- 0.23 vs 1.17 +/- 0.20 U/ml, p < 0.05; VIIag 537.7 +/- 127.7 vs 479.4 +/- 93.4 ng/ml, p < 0.001). The parallel increase was accounted for by patients with hypertriglyceridaemic lipoprotein phenotypes. In contrast, the level of activated factor VII (VIIa) neither differed significantly between patients and controls, nor between patients with different lipoprotein phenotypes. The elevated TFPI activity in the patients was closely associated with the plasma level of dense low density lipoprotein (LDL) particles (r = 0.46, p < 0.001) and with the plasma concentration of the small, dense high density lipoprotein (HDL) subspecies HDL3b (r = 0.34, p < 0.01).

Measurement of Basal Levels of Factor Vila in Hemophilia A and B Patients

Previous results, presented in abstract form, indicate that replacement of thromboplastin with a mixture of phospholipid and truncated soluble tissue factor apoprotein results in a coagulation assay that can directly measure plasma factor VIIa levels without interference from zymogen factor VII (Atherosclerosis Thromb 11:1544a, 1991 [abstr]). We have exploited the specificity and sensitivity of such a factor VIIa specific coagulation assay to directly assess the in vivo relationship of factor VIII and factor IX on the production of factor VIIa levels under nonthrombotic and nonstimulatory conditions. Normal individuals (n = 20) were found to possess an average circulating factor VIIa level corresponding to 4.34 +/- 1.57 ng/mL, or approximately 1% of their total factor VII antigen. Severe factor VIII deficient patients (n = 13) possessed a slightly lower but statistically significant (P less than .01) decrease in their basal factor VIIa levels (2.69 +/- 1.52 ng/mL), corresponding to approximately 60% of that observed in normal individuals. On the other hand, severe factor IX deficient patients (n = 7) were found to possess even lower levels of factor VIIa corresponding to 0.33 +/- 0.15 ng/mL, or less than 10% of that observed in normal individuals. Measurement of total factor VII antigen levels shows that the variation in basal factor VIIa levels stems from differences in the degree of factor VII activation as opposed to differences in factor VII antigen levels. Our present data are consistent with the hypothesis that factor IXa is the principal in vivo activator of factor VII under basal conditions.

Measurement of basal levels of factor VIIa in hemophilia A and B patients [see comments

Previous results, presented in abstract form, indicate that replacement of thromboplastin with a mixture of phospholipid and truncated soluble tissue factor apoprotein results in a coagulation assay that can directly measure plasma factor VIIa levels without interference from zymogen factor VII (Atherosclerosis Thromb 11:1544a, 1991 [abstr]). We have exploited the specificity and sensitivity of such a factor VIIa specific coagulation assay to directly assess the in vivo relationship of factor VIII and factor IX on the production of factor VIIa levels under nonthrombotic and nonstimulatory conditions. Normal individuals (n = 20) were found to possess an average circulating factor VIIa level corresponding to 4.34 +/- 1.57 ng/mL, or approximately 1% of their total factor VII antigen. Severe factor VIII deficient patients (n = 13) possessed a slightly lower but statistically significant (P less than .01) decrease in their basal factor VIIa levels (2.69 +/- 1.52 ng/mL), corresponding to approximately 60% of that observed in normal individuals. On the other hand, severe factor IX deficient patients (n = 7) were found to possess even lower levels of factor VIIa corresponding to 0.33 +/- 0.15 ng/mL, or less than 10% of that observed in normal individuals. Measurement of total factor VII antigen levels shows that the variation in basal factor VIIa levels stems from differences in the degree of factor VII activation as opposed to differences in factor VII antigen levels. Our present data are consistent with the hypothesis that factor IXa is the principal in vivo activator of factor VII under basal conditions.

Factor VII Hyperactivity in the Elderly

To investigate the age-related increase in coagulation factor VII (FVII) and its significance in the elderly, we measured FVII coagulation activity (FVIIc), FVII antigen (FVIIag), and D-dimer levels in 150 normal subjects ranging in age from 60 to 98 years. We also measured blood lipid fractions and serum cholinesterase activity (ChE), as an indicator of hepatic protein synthesis. FVIIc (141 +/- 36%), FVIIag (136 +/- 28%), and D-dimer (0.150 +/- 0.372 microgram/ml) levels were significantly higher in the elderly than in younger controls (p less than 0.01). Both FVIIc and FVIIag levels were significantly higher in elderly women than in elderly men (p less than 0.01). FVIIc levels significantly correlated with FVIIag levels, but not with D-dimer levels. FVIIag was more closely correlated with ChE levels in both sexes (men: r = 0.425, women: r = 0.365, p less than 0.001) than with the lipid fractions. When the elderly subjects were divided into atherosclerotic and non-atherosclerotic groups, both FVIIc (p less than 0.01) and FVIIag (p less than 0.05) levels were higher in the former group. Moreover, the FVIIc/FVIIag ratio and ChE levels were higher in both the elderly men and women with atherosclerosis. These results suggest that in elderly subjects, especially with atherosclerosis, hepatic FVII synthesis and the activation of FVII zymogen are both accelerated.

Congenital Factor VII Abnormality Discovered in an Infant at a Routine Checkup

Congenital coagulation factor VII abnormality in an infant was first discovered because of a decreased normotest value at a routine health checkup at the age of 1 month. No bleeding tendency had been noticed. The normotest value did not respond to an administration of vitamin K. The prothrombin time (PT) was prolonged, and the activated partial thromboplastin time (A-PTT) was in the normal range. Factor VII activity was extremely low, whereas the level of factor VII antigen was relatively low. These data indicate that the propositus is a factor VII reduced variant, a rare variant of congenital factor VII deficiency. The propositus and her brother are homozygotes, and her parents and sister are heterozygotes.

高齢者の血清尿酸値と高凝固第ＶＩＩ因子血症

To study the relationship between serum uric acid, lipid fractions, and coagulation factor VII (FVII) in the elderly, we measured FVII coagulation activity (FVIIc). FVII antigen (FVIIag), in 138 normal subjects without alcohol intake ranging in age from 60 to 98 years. We also measured blood lipid fractions including apolipoprotein A-I, A-II, B, E, and serum cholinesterase activity (ChE). Serum uric acid levels significantly correlated with FVIIc (p less than 0.01) and FVIIag levels (p less than 0.05) as well as with tryglycerides, VLDL, LDL, total cholesterol, and ChE in elderly men, but not in women. However, multiple regression analysis showed these correlations in elderly men were not significant, after excluding the effect of triglycerides and VLDL. These results also suggest that elevation of uric acid may be a coronary risk factor in elderly men through high FVII levels.

An arginine to cysteine amino acid substitution at a critical thrombin cleavage site in a dysfunctional factor VIII molecule

We have analyzed the factor VIII (FVIII) protein and the nucleotide sequence around two thrombin cleavage sites, at arginine 372 in the FVIII heavy chain and arginine 1689 in the FVIII light chain in a naturally occurring dysfunctional FVIII variant, FVIII Okayama. The patient was a 42-year-old hemophiliac with a FVIII coagulant activity of 0.03 U/mL and a FVIII antigen level of 0.8 U/mL. The patient's FVIII was not thrombin activatable to levels seen in normal plasma. Immunoblotting of partially purified FVIII Okayama and normal FVIII showed that thrombin cleavage of the 92 kilodalton (Kd) heavy chain was impaired in the mutant protein. The patient's genomic DNA was amplified using the polymerase chain reaction with two sets of synthetic oligonucleotide primers spanning amino acid residues 319 to 400 and 1630 to 1720. Sequence analysis of the amplified DNA fragments revealed a cytosine to thymine transition, converting an arginine to a cysteine codon at residue 372. No abnormality was found in the FVIII light chain region analyzed. The patient's hemophilic brother and carrier mother revealed the same mutation. We conclude that the pathogenesis of hemophilia A in this patient is probably due to an arginine to cysteine substitution at a thrombin cleavage site in the FVIII heavy chain.

An Arginine to Cysteine Amino Acid Substitution at a Critical Thrombin Cleavage Site in a Dysfunctional Factor VIII Molecule

We have analyzed the factor VIII (FVIII) protein and the nucleotide sequence around two thrombin cleavage sites, at arginine 372 in the FVIII heavy chain and arginine 1689 in the FVIII light chain in a naturally occurring dysfunctional FVIII variant, FVIII Okayama. The patient was a 42-year-old hemophiliac with a FVIII coagulant activity of 0.03 U/mL and a FVIII antigen level of 0.8 U/mL. The patient's FVIII was not thrombin activatable to levels seen in normal plasma. Immunoblotting of partially purified FVIII Okayama and normal FVIII showed that thrombin cleavage of the 92 kilodalton (Kd) heavy chain was impaired in the mutant protein. The patient's genomic DNA was amplified using the polymerase chain reaction with two sets of synthetic oligonucleotide primers spanning amino acid residues 319 to 400 and 1630 to 1720. Sequence analysis of the amplified DNA fragments revealed a cytosine to thymine transition, converting an arginine to a cysteine codon at residue 372. No abnormality was found in the FVIII light chain region analyzed. The patient's hemophilic brother and carrier mother revealed the same mutation. We conclude that the pathogenesis of hemophilia A in this patient is probably due to an arginine to cysteine substitution at a thrombin cleavage site in the FVIII heavy chain.

Coagulation factor VII and plasma triglycerides. Decreased catabolism as a possible mechanism of factor VII hyperactivity.

High circulating levels of coagulation factor VII (FVII) are known to be associated with elevated concentrations of blood lipids. More specifically, hypertriglyceridemia is correlated with raised FVII coagulant activity (FVIIc). Recently, evidence has been described which suggests that elevation in FVIIc might reflect an increase in the total concentration of FVII, as evaluated by quantitation of FVII antigen (FVIIag). It is also known that FVIIc represents a risk factor for cardiovascular death, but the prediction of cardiovascular risk based on triglyceride estimation is the subject of conflicting results. Since dyslipidemia featuring abnormal triglyceride metabolism is pathophysiologically heterogeneous, we analyzed the possible relationships between FVII and triglyceride further and under standardized postprandial conditions. For this purpose we studied FVIIc and FVIIag in relation to triglyceridemia after a standardized test meal. Our results confirm that FVIIc and FVIIag levels are strongly correlated with each other (r = 0.714; p = 0.01). In addition, both were significantly increased (p less than 0.02) in patients who exhibited abnormal triglyceride levels 8 h after a standardized test meal, as compared to those who displayed normal triglyceridemia. Furthermore, we found that apolipoprotein B levels were also increased in such patients. The deficient postprandial catabolism of triglycerides, therefore, appears to be related to an increase in total FVII concentration, suggesting that some association between the metabolism of triglyceride-rich lipoproteins and FVII might underlie the mechanism of the elevation in FVII. Given the important contribution of FVII to hypercoagulability, then our results may be relevant to the understanding of the role of postprandial triglyceride in atherogenesis and in consideration of the circadian prevalence of cardiovascular thrombosis.

Plasma factor VII, triglyceride concentration and fibrin degradation products in primary hyperlipidemia: a clinical and laboratory study.

There is evidence that the increase in coagulation factor VII (FVII) represents a predictive risk factor of arterial thrombosis in coronary heart disease. Its relative contribution to this multifactorial process and its relationship to other risk factors, namely cholesterol and triglycerides, is yet a matter of investigation. In this study we aimed to clarify whether FVII synthesis or activation correlated with plasma lipid concentrations. For this, we assayed the plasma levels of FVII antigen (FVII:ag) and FVII coagulant activity (FVIIc) in types IIa, IIb and IV hyperlipidemic individuals, together with the levels of cholesterol, triglycerides, high-density lipoproteins and apolipoprotein B. FVII activation state (FVIIa) was then assessed by FVIIc/FVII:ag. In order to assess the possible correlation of FVII levels with the generation of thrombin and formation of fibrin, we also assayed the plasma concentration of fibrin degradation products (D-dimers) in these patients. Considering all the patients studied, there was a fair correlation between FVIIc and FVII:ag (r = 0.704; p less than 0.01). The mean levels of FVIIc and FVII:ag were significantly higher in type IV hyperlipidemia than in controls (t = 4.260; p less than 0.001 and t = 3.015; p less than 0.01, respectively) and other types of hyperlipidemia. We also found that FVIIc and FVII:ag significantly correlated to triglyceride concentration. We could not detect an evident activation of FVII in these patients since FVIIc/FVII:ag was not elevated in comparison with controls, nor did it correlate with any of the lipid determinations in any of the types of hyperlipidemia studied.(ABSTRACT TRUNCATED AT 250 WORDS)

Study of different factor VII deficiency variants in nine families from Spain.

Twenty-three patients with congenital factor VII (FVII) deficiency, belonging to 9 kindreds were studied. Immunological variants were classified according to the relationship between FVII coagulant activity (FVIIC) and the level of FVII antigen (FVIIAg), considering 3 previously described groups: VII-, VII+ and VIIR. Activation variants were determined by the reactivity pattern with three different thromboplastins. One patient was classified as VII-, 16 as VII+, and 6 as VIIR. Three patients belonging to the same kindred showed a Padua 2 FVII deficiency, and 1 patient showed a Padua 1 variant. There was no correlation between antigenic or activation variants and severity of bleeding tendency. Classical autosomal recessive mode of inheritance was observed in VII- and VII+ families. Nevertheless, a possible autosomal dominant trait was observed in VII+ kindreds.

Ｌａｕｒｅｌｌ法による第ＶＩＩ因子抗原の測定 基礎的および臨床的検討

Factor VII antigen has been measured with the antibody neutralization assay according to Goodnight, until recent report of Fair in which a double-antibody equilibrium radio-immunoassay for factor VII antigen is employed. No quantitative precipitation arc of factor VII antigen in plasma has been reported because of its very low concentraiton.In the present method developed by the authers, a clear precipitation arc of factor VII antigen appeared by immuno-electrophoresis using 125I-labelled anti-factor VII antibody incorporated in the Laurell plate to enhance the sensitivity. A plasma sample was electrophoresed directly on 1% agarose containing 1% anti-human factor VII rabbit serum, 0.1% 125I-labelled anti-human factor VII specific IgG and 0.5% polyethyleneglycol 6000, and after washing, autoradiographed at -70°C for 48hr. A distinct rocket was seen from 45μl of undiluted plasma to 16-fold diluted plasma. Of 5 cases with congential factor VII deficiency, 4 cases had no detectable factor VII antigen, one case had factor VII antigen. Factor VII antigen levels in 19 patients of liver disease varied from 9 to 125%, and the assayed values of factor VII antigen and activity correlated relatively well (r=0.96). In contrast, factor VII antigen levels in 20 patients treated with Warfarin varied from 16 to 100%, and the antigen levels were slightly higher than the activity.

Studies on immunological assay of vitamin K dependent factors. I. Measurement of factor VII antigen by radioimmunoassay.

A radioimmunoassay (RIA) for factor VII was developed using 125I-factor VII, anti-factor VII rabbit serum and anti-rabbit IgG goat serum. The lower limit of sensitivity in normal reference plasma was 3 X 10(-3) units/ml. Although the level of factor VII antigen (VII:Ag) in normal plasma samples (n = 20) 0.944 +/- 0.176 units/ml, correlated with that of factor VII coagulant activity (r = 0.89), VII:Ag level in paired normal sera showed a higher value (1.469 +/- 0.376 units/ml). The level of antigen according to RIA of factor VIIa activated by factor Xa increased 2.5-fold compared with that of unactivated factor VII. It is suggested that the polyclonal anti-factor VII produced in a rabbit had higher affinity for factor VIIa than for factor VII. In two out of seven patients with congenital factor VII deficiency, VII:Ag was detectable (0.04, 0.31 units/ml, respectively) whereas VII:C was less than 0.01 units/ml. In 12 warfarin-treated individuals, VII:C showed a lower level (0.121 +/- 0.063 units/ml) that that of VII:Ag (0.518 +/- 0.186 units/ml). During 4 weeks observation after stopping warfarin, VII:C and VII:Ag reached normal levels in 1 week. However, VII:C did not reach equivalence with VII:Ag until 4 weeks had elapsed.

The Inability of Propranolol and Aspirin to Inhibit the Response of Fibrinolytic Activity and Factor VIII-Antigen to Infusion of DDAVP

We tested the response of the fibrinolytic activity and factor VIII-antigen levels to infusion of DDAVP in healthy volunteers and we studied the influence of propranolol and aspirin on this response. After DDAVP, 0.4 microgram/kg in 10 min i.v., the fibrinolytic activity of redissolved euglobulins rose from 179 to 452 mm2 (lysis area of fibrin plates); after pretreatment with propranolol, 320 mg per day during 7 days, DDAVP induced a similar rise (from 166 to 471 mm2) and after pretreatment with a single dose of aspirin, 600 mg, ingested 5 hr before the DDAVP infusion, the lysis area increased from 159 to 455 mm2. Factor VIII-antigen level increased within 60 min after DDAVP from 104 to 208%; after pretreatment with propranolol from 111 to 230% and after a single dose of aspirin, DDAVP induced a rise from 107 to 206%. From these data we conclude that neither baseline levels nor the release of plasminogen activator or factor VIII after DDAVP infusion are influenced by beta-blockade or by interference with prostaglandin synthesis.