A comparison of methods for the measurement of activated factor VII

A number of different methods are available for the measurement of factor VIIa. Almost all of these employ ratios of two different measurements of factor VII. In order to determine which is the most sensitive to activated factor VII we have compared currently available methods in the following groups: two patients with haemophilia A following treatment with activated recombinant factor VII (rVIIa); 6 normal plasmas during cold promoted activation of factor VII; normal individuals (n = 23); and patients with unequivocal disseminated intravascular coagulation (DIC, n = 19). Factor VII was measured in an amidolytic assay (VII:Amid) and an antigen assay (VII:Ag). Clotting activity was measured using rabbit (VII:C Rab), human (VII:C Hum) and bovine (VII:C Bov) thromboplastin. Of the clotting assays the most sensitive to the presence of factor VIIa was that which utilised bovine thromboplastin. Amidolytic and immunological measurements were unaffected by the activity state of factor VII. The ratios VII:C Rab/VII:Ag and VII:C Rab/VII:Amid were insensitive to activated factor VII. The ratios most sensitive to the presence of factor VIIa were VII:C Bov/VII:Amid and VII:C Bov/VII:Ag. The ratios VII:C Bov/VII:C Rab and VII:C Bov/VII:C Hum are less sensitive but have the advantage for epidemiological studies of narrower reference ranges.

A randomized controlled trial of recombinant interferon-alpha in chronic hepatitis C in hemophiliacs

Chronic liver disease associated with hepatitis C virus (HCV) is an important cause of morbidity and mortality in hemophilia. We have used recombinant interferon alpha-2b (IFN alpha-2b) in a randomized controlled liver biopsy trial to treat hemophiliacs with chronic hepatitis. Eighteen patients entered the study, 16 of whom were subsequently shown to have antibodies to the HCV. All underwent liver biopsy at entry and were randomized to either treatment with self-administered IFN alpha-2b, 3 million units subcutaneously thrice weekly (n = 10) or no treatment (control group) (n = 8). Nine subjects had chronic active hepatitis, seven had chronic persistent hepatitis, and two had cirrhosis. Twelve months after entry into the study 17 patients underwent a second liver biopsy. All biopsies were coded, assessed, and scored according to the histologic severity of the liver disease. Ten patients were administered IFN for 1 year, and in four patients normalization of alanine aminotransferase (ALT) occurred compared with none in the untreated group. After the second liver biopsy, six of the eight initial no-treatment patients were treated with interferon 3 million units thrice weekly for 6 months, and normalization of ALT was seen in five patients. Biochemical relapse within 4 months of stopping IFN occurred in one of four patients treated for 1 year and in four of five patients treated for 6 months. IFN treatment was well tolerated. Although the histologic scores of the two groups were similar at entry into the study, after 12 months the biopsy appearances in the treated group were significantly improved compared with the controls (P less than .01). Histologic improvement was noted in the three interferon-treated human immunodeficiency virus antibody-positive patients and also in other patients who had no biochemical response. We conclude that low-dose recombinant IFN alpha is effective in normalizing transaminases and improving the histologic appearances in at least 50% of hemophiliacs with chronic hepatitis C.

Familial antithrombin III deficiency and Mycoplasma pneumoniae pneumonia

A 10 year old girl presented with a massive femoral vein thrombosis associated with Mycoplasma pneumoniae pneumonia. Subsequently type I familial antithrombin III deficiency was diagnosed. It is suggested that prophylactic measures aimed at preventing thrombosis should be considered in acutely ill subjects with infection and familial thrombophilia.

Potential thrombogenicity of heat-treated prothrombin complex concentrates in Haemophilia B

We have studied the potential thrombogenicity of two different heat-treated prothrombin complex concentrates (PCC) in patients with Haemophilia B. Seven patients were studied on nine separate occasions. Four of the patients had chronic hepatitis C (HCV) associated liver disease and three were HIV-antibody positive. The PCCs were Profilnine (Alpha Therapeutics, Thetford, UK) and 9A (Bio-Products Laboratory, Elstree, UK) and the dose administered ranged from 35 to 60 U/kg. Blood samples were taken on ten separate occasions; twice before the infusion and at 15, 40, 60, 75 and 120 min and 4, 8 and 24 h after the infusion of PCC. Investigations included prothrombin time, kaolin cephalin clotting time, thrombin time, fibrin(ogen) degradation products, factor VIII, factor IX, antithrombin III and fibrinopeptide A (FPA). Fibrinopeptide A rises were seen following two of six infusions of 9A and one of three infusions of Profilnine. On all three occasions the rise in FPA was transient, returning to baseline levels within 120 min. Plasma beta-thromboglobulin (BTG) was assayed in three patients and in one patient, the rise in FPA was followed by an increase in BTG. No other changes were observed and there were no clinical features of disseminated intravascular coagulation. Our results indicate that even with normal clinical doses of PCC, intravascular thrombin generation can occur in patients with Haemophilia B. However, this effect is inconsistent both with respect to PCC batch and patient, but may occur in the absence of HIV infection and HCV liver disease.

The effects of diet and insulin therapy on coagulation factor VII, blood viscosity, and platelet release proteins in diabetic patients with secondary sulphonylurea failure

The effect of intensified dietary measures and subsequently insulin therapy upon haemorheological measures were studied in Type 2 diabetic patients with secondary sulphonylurea failure. Coagulation factors VIIc and VIIIc, fibrinogen, plasma viscosity, whole blood viscosity, beta-thromboglobulin, platelet factor 4, von Willebrand factor, and euglobulin clot lysis time were measured at baseline, after 3 months intensified dietary therapy and after 4 months insulin therapy. During intensified dietary therapy there was a significant fall in serum cholesterol (p less than 0.05) and a small decrease in weight, but no significant change in blood glucose control. Factor VIIc levels fell significantly (1.22 (SE 0.07) vs 1.42 (0.08) u ml-1, p less than 0.01), and plasma viscosity and whole blood viscosity (23 s-1) also improved (both p less than 0.05). Insulin therapy was instituted with either continuous subcutaneous insulin therapy or twice daily injections of soluble and isophane (NPH) insulin. During this period glycosylated haemoglobin improved (mean (SE) 49.5 (1.4) vs 65.0 (2.1) mmol-HMF mol-Hb-1, p less than 0.001; normal range 29-39 mmol-HMF mol-Hb-1) as did serum triglyceride (p less than 0.01), but weight increased (p less than 0.001). The only haemorheological changes with insulin were increased levels of the platelet release proteins beta-thromboglobulin (37 (3) vs 28 (2) micrograms l-1, p less than 0.01) and platelet factor 4 (median 7.5 (range 3.0-18.0) vs 4.5 (2.0-10.5) micrograms l-1, p less than 0.01).

Activation of coagulation in diabetes mellitus in relation to the presence of vascular complications

To examine the relationship between diabetic vascular disease and haemostasis, a set of sensitive assays has been used to assess in vivo activation of coagulation in 62 diabetic patients (41 Type 1 and 21 Type 2), aged 19-68 years, who had been screened for the presence of complications. Fibrinopeptide A, an index of thrombin activity, was significantly increased in diabetic patients compared with control subjects (p less than 0.05), in both plasma (with complications mean 8.04 +/- 11.87 (+/- SD); without complications 7.21 +/- 10.13; control subjects 2.11 +/- 1.40 micrograms l-1) and urine (with complications mean 1.48 +/- 0.74; without complications 1.35 +/- 0.62; control subjects 0.98 +/- 0.39 micrograms l-1). Activated factor VII (VIIa ratio 1.21 +/- 0.39; 1.13 +/- 0.23; 1.01 +/- 0.11) and fibrinogen (3.15 +/- 0.59; 3.11 +/- 0.69; 2.70 +/- 0.57 g l-1) were also elevated in diabetic patients with and without complications (VIIa p less than 0.05, fibrinogen p less than 0.01). The only difference between Type 1 and Type 2 patients was in fibrin degradation products (Type 1 0.28 +/- 0.18; Type 2 0.40 +/- 0.18 mg l-1, p less than 0.01). Plasma levels of fibrin degradation products were elevated in diabetic patients (p less than 0.05 vs control subjects), and correlated with age (r = 0.44, p less than 0.01) but were unrelated to the presence of complications. There were no significant differences in any coagulation variables between diabetic patients with and without complications.(ABSTRACT TRUNCATED AT 250 WORDS)

GENESRCH: a computer program for restriction fragment analysis

We describe a program GENESRCH which has been written to enable the design of efficient restriction fragment analysis of DNA from patients with hereditary disorders. The program identifies homology of DNA sequences up to 20 base pairs in length, calculates the fragment sizes and indicates the position of enzyme restriction sites within the gene of interest. GENESRCH is written in the BASIC language and will run on any IBM-compatible PC with a parallel printer. A hard disc is recommended for efficient storage and retrieval of data. An example of the use of the program is cited.

Demonstration of viraemia patterns in haemophiliacs treated with hepatitis-C-virus-contaminated factor VIII concentrates

Sequential serum samples from previously untreated haemophiliacs in whom non-A, non-B hepatitis (NANBH) developed after they received factor VIII concentrate contaminated with hepatitis C virus (HCV) were tested by a commercial assay for the presence of antibodies to the C100 protein of HCV (anti-C100) and by "nested" PCR for the presence of HCV RNA sequences. Three temporal patterns of viraemia were observed: transient viraemia in acute resolving NANBH; viraemia lasting for several years in chronic NANBH; and intermittent viraemia in chronic NANBH, with an initial transient phase followed by recurrence after many months. In three of five cases the initial detection of serum HCV RNA was made before the onset of liver function test abnormality, many weeks or months before anti-C100 seroconversion. Diagnosis of acute HCV infection may therefore be possible much earlier by PCR than by existing serological techniques, but the timing of samples may be critical.

Platelet aggregation by oral streptococci

One proposed mechanism in the pathogenesis of infective endocarditis is the direct aggregation of platelets by the bacteria causing the disease. Some, but not all, strains of Streptococcus sanguis have been reported to aggregate platelets but the taxonomy of this and related taxa has changed recently. The ability to aggregate platelets by 24 genetically grouped laboratory stock strains was studied along with 8 recent isolates from cases of endocarditis. Strains belonging to S. sanguis could aggregate platelets, but not S. gordonii, "S. parasanguis", S. mitis, S. oralis or related taxa. Also, preliminary data indicate that certain biotypes of S. sanguis lack the ability to aggregate platelets. Of the recent clinical isolates, only 4 aggregated platelets and each of these showed phenotypes typical of S. sanguis. These data suggest that the ability to aggregate platelets is not essential for an organism to be able to cause endocarditis, although it may be a significant virulence factor.

Inhibition of activated protein C and its cofactor protein S by antiphospholipid antibodies

We have investigated the effects of purified IgG fractions from plasma containing the lupus anticoagulant (LAC) and/or IgG anticardiolipin antibody (ACA) on the degradation of factor Va by an activated protein C-protein S complex. Plasma samples from 10 patients were studied. LAC was detected by a Russell's Viper venom technique. ACA was determined by ELISA. IgG fractions were obtained from each plasma sample by protein A-Sepharose fractionation. This fraction was shown to exhibit ACA/LAC activity. Using purified activated protein C (APC), protein S and phosphatidylserine/phosphatidylcholine, factor Va degradation was assessed in the presence and absence of IgG fractions from LAC/ACA containing plasmas. After 2 min incubation the mean factor Va degradation by APC and protein S in the presence of IgG LAC/ACA fractions was 14% compared with 52% with normal IgG. A similar effect was seen when phospholipid was substituted by washed freeze-thawed platelets. Experiments employing varying concentrations of protein S and phospholipid revealed marked differences in respect of the inhibitory specificity of the different antiphospholipid antibodies. These results indicate that antiphospholipid antibodies have an inhibitory effect on the activated protein C/protein S complex and provide some explanation for a relationship between antiphospholipid antibodies and thrombosis.

Induction of immune tolerance in patients with hemophilia A and inhibitors treated with porcine VIIIC by home therapy

Home therapy with porcine factor VIIIC was safe and effective when administered to five hemophilic patients over periods of 8 1/2, 6, 4, 3 1/2, and 2 years. No significant transfusion reactions occurred. Before treatment with porcine factor VIIIC, all five had high-level, high-responding anti-human VIIIC inhibitors initially lacking anti-porcine factor VIIIC activity. Although specific anti-porcine VIIIC inhibitors arose in all patients, these were generally transient, and only one patient became refractory to treatment. We believe that porcine factor VIIIC is the treatment of choice in patients whose inhibitors do not cross-react. All five patients lost their original anti-human VIIIC inhibitors after starting treatment with porcine VIIIC, permitting the reintroduction of human VIIIC in three of them. There has been no recurrence of anti-human VIIIC inhibitor activity during 2 to 3 years of regular treatment with human VIIIC in these patients. This suggests that tolerance to human VIIIC has arisen as a result of treatment with porcine VIIIC. Porcine VIIIC may have a role in the desensitization of some factor VIIIC inhibitor patients.

Rapid assessment of haemophilia A carrier state by non-invasive techniques using the polymerase chain reaction

The polymerase chain reaction (PCR) was used to amplify two polymorphic regions in the factor VIII gene. In vitro synthesis of DNA was achieved using samples obtained from buccal cells, urine, and hair follicles in addition to purified genomic and crude DNA samples prepared from whole blood. Female members of two kindreds affected with haemophilia A were assessed for carrier state using direct restriction fragment length polymorphism analysis of amplified gene products in the Bc1I and XbaI regions. It is concluded that this is a non-invasive, rapid, and inexpensive technique for carrier detection.

Hepatitis C antibody and chronic liver disease in haemophilia

A radioimmunoassay was used to detect antibodies to hepatitis C virus (anti-HCV) in 154 patients with haemophilia. Prevalence of anti-HCV was associated with exposure to clotting factor concentrates. 76 of 129 (59%) who had received factor VIII or IX had anti-HCV: 42 of 55 (76%) who required over 10,000 units of concentrate annually had anti-HCV, compared with 34 of 74 (46%) who required less, and 0 of 25 patients who had never received concentrates. Anti-HCV were significantly more common in patients seropositive for antibodies against human immunodeficiency virus (anti-HIV) or with markers of previous hepatitis B infection than in those without anti-HIV or hepatitis B markers (88% vs 39% and 75% vs 46%, respectively). 5 of 23 (22%) haemophiliacs treated only with heated concentrates had anti-HCV compared with 71 of 106 (67%) patients who received unmodified products. 35 patients with chronic liver disease underwent liver biopsy: histological examination showed features associated with post-transfusion hepatitis in 24, all of whom were anti-HCV-positive; of the other 11 patients with no histological features of non-A, non-B hepatitis, 5 were anti-HCV-positive. HCV appears to be the major predisposing factor for most non-A, non-B hepatitis and chronic liver disease in haemophilia.

A comparative evaluation of assays for markers of activated coagulation and/or fibrinolysis: thrombin-antithrombin complex, D-dimer and fibrinogen/fibrin fragment E antigen

Measurements were made of levels of D-dimer in plasma and serum, thrombin-antithrombin complex (TAT) in plasma and fibrinogen/fibrin fragment E antigen (FgE) in serum in a normal healthy control group and in patients with a range of disorders associated with hypercoagulability. Levels were determined in 31 normal healthy controls, 30 patients with disseminated intravascular coagulation (DIC), 21 patients with deep venous thrombosis (DVT), 27 patients with myocardial infarction (MI), 26 patients with acute leukaemia and 56 patients with liver disease. Considering all subjects, significant correlations were established between the results of all assays. Notably high correlations (r greater than 0.9) were established between plasma and serum levels of D-dimer, between plasma levels of D-dimer and serum levels of FgE, and between serum levels of D-dimer and FgE. All assays showed very high discrimination (sensitivity) between the normal control group and patients with DIC (97-100%), but there were marked differences between the assays in sensitivity for DVT and MI. In general, the FgE assay was more sensitive than the D-dimer assay, whilst both the FgE and D-dimer assays were more sensitive than the TAT assay. The same trends were apparent in the capability of the assays to discriminate between the normal control group and patients with acute leukaemia and liver disease: disorders with an unknown prevalence of activation of coagulation/fibrinolysis. Our results indicated that measurements of fibrinogen/fibrin degradation products (FDPs) in serum were almost unaffected by artefacts. The data further suggested that the broad-spectrum FgE assay was better than the more specific D-dimer assay in detecting clinical hypercoagulability. Our study showed that, in the clinical conditions examined, FDPs were more effective markers of hypercoagulability than TAT.

Coagulation disturbances following ascites recirculation

To investigate the effects of extra-corporeal ascites recirculation on coagulation, several coagulation variables were measured in ascitic return fluid and plasma before, during and after this procedure in 16 patients with diuretic resistant ascites. Small but significant reductions in plasma fibrinogen levels and platelet counts and increases in plasma X-oligomer were observed during and after the procedure compared with before. These findings are consistent with the view that ascites recirculation induces disseminated intravascular coagulation although this would appear to be only mild and of no clinical significance in the majority of patients. Although increased levels of activated factor VII were observed in ascitic fluid indicating activation of the extrinsic pathway of coagulation, a significant increase in plasma activated factor VII during the procedure was not demonstrated. Increased fibrinolytic activity was observed in ascitic fluid due to the presence of tissue plasminogen activator. Increased X-oligomer levels were observed in ascitic fluid indicating that lysis of cross-linked fibrin is also an active process within ascites.

A placebo-controlled, double-blind study of eicosapentaenoic acid-rich fish oil in patients with stable angina pectoris

A study was carried out to evaluate the clinical and haematological effects of dietary supplementation with eicosapentaenoic acid (EPA)-rich fish oil (MaxEPA', 2.8 g EPA daily) compared to placebo (olive oil) in 10 patients with stable angina pectoris. After 3 months, there was a significant increase in red cell deformability (p less than 0.001), reduced whole blood viscosity (p less than 0.02), and prolonged skin bleeding time (p less than 0.001) in the fish oil group compared to the placebo group. Haematocrit, plasma viscosity, fibrinogen concentration, platelet count, and in vitro platelet aggregation were unaltered. No significant symptomatic or objective improvement was noted in angina pectoris in either group despite the significant rheological changes produced in the patients receiving fish oil.

Recurrent multiple-branch retinal arteriolar occlusions in a patient with protein C deficiency

A 34-year-old woman is presented who has recurrent, multiple, retinal arteriolar occlusions associated with a deficiency in protein C, a vitamin K-dependent anticoagulant. Protein C is a naturally occurring anticoagulant and if there is a deficiency, it can lead to episodes of thrombosis; the deficiency can be acquired or congenital. This is the first documented case of retinal arteriolar occlusion associated with a congenital deficiency of this protein. The mechanism for arteriolar occlusion in this patient is discussed, and whilst the role of protein C deficiency remains presumptive, it is strongly implicated.

DN 9693: a phosphodiesterase inhibitor with a platelet membrane effect

We have examined the in vitro effects of DN 9693 (piperidinylimidazo-quinazolinone) on various aspects of platelet reactivity. Our results are consistent with its known function as a phosphodiesterase inhibitor in that it increased platelet cyclic AMP, particularly in conjunction with an adenylate cyclase stimulator, and exerted a profound inhibitory effect on platelet aggregation responses to a variety of agonists. DN 9693 also inhibited ristocetin-induced platelet agglutination (RIPA). We therefore examined its effect on ristocetin co-factor assays and on the binding of a monoclonal antibody (McAb) to platelet membrane glycoprotein Ib (GPIb). The drug inhibited the binding of the monoclonal antibody in a dose-dependent manner. This suggests an effect of the drug on the platelet surface membrane with reduced expression of GPIb. Our results indicate that in addition to its anticipated inhibitory effect on platelet aggregation, DN 9693 may also inhibit platelet adhesion.