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Plasma viscosity, molecular markers of activated coagulation and fibrinolysis (fibrinopeptides A and B beta 15-42), coagulation factors (fibrinogen and factor VII) and antiplasmins were measured in 529 men aged 35-54 years and related to new angina pectoris (n = 117) and to coronary risk factors in controls without angina (n = 412). Five major risk factors (cigarette-smoking, blood pressure, cholesterol, triglyceride and body mass index) were each associated with increases in plasma viscosity, coagulation factors, and imbalance of coagulation over fibrinolysis (increased ratio of fibrinopeptide A/fibrinopeptide B beta 15-42). Increased viscosity and fibrinogen in smokers were partly reversed in ex-smokers, but the imbalance of coagulation and fibrinolysis persisted. Cholesterol and triglyceride were also associated with increased antiplasmin activity. In men with angina, only fibrinogen was elevated compared to controls. We suggest that increased plasma viscosity and an imbalance of coagulation over fibrinolysis may be mechanisms by which known risk factors promote arterial thrombosis, but are not present in stable angina.

56 haemophiliacs selected on the basis of HIV-1 antibody status, liver disease grade and mean annual dose of clotting factor concentrate used were studied. Spontaneous and stimulated IgG and IgM production in vitro were measured. HIV-1 infection was associated with increased spontaneous immunoglobulin production and an impaired response to pokeweed mitogen and Staph Aureus protein A. Implying a shift in the proportions of partially and fully activated B cells. In the absence of HIV-1 infection there was a shift to a greater proportion of partially activated B cells in patients with severe liver disease. The remainder had in vitro immunoglobulin production comparable to controls. B cell abnormalities occur early in the course of HIV-1 infection. Liver disease and not clotting factor concentrate treatment cause B cell abnormalities in the absence of HIV-1 infection in haemophilia.

Plasma fibrinogen and platelet-aggregates (method of Wu and Hoak) were measured in 21 patients with familial Type II hyperlipoproteinemia and 21 matched control subjects. Patients with hyperlipoproteinaemia had increased levels of fibrinogen and platelet-aggregates (p less than 0.01). Young patients with hyperlipoproteinaemia had prematurely high fibrinogen levels, and the normal rise in fibrinogen during adult life was abolished. There were no statistically significant correlations within the patient group between fibrinogen, platelet-aggregates, and plasma lipids. High fibrinogen and platelet-aggregate levels may play a part in the development of the premature arterial disease associated with Type II hyperlipoproteinaemia, or may be markers of arterial injury.

Des-amino-D-arginine vasopressin (DDAVP) stimulates the release of factor VIII and plasminogen activator from the vascular endothelium. An infusion of exogenous factor VIII given to haemophiliacs causes an increase in platelet activation. This activation does not occur after stimulating a rise in the patient's own factor VIII level caused by DDAVP infusion. We hypothesised therefore that DDAVP could also cause the endothelial release of prostacyclin (PGI2), a potent anti-platelet agent which would counteract the aggregating effect of factor VIII. To examine this possibility we studied the effect of DDAVP on prostacyclin release, as measured by its stable metabolite 6-oxo-PGF1 alpha, in vitro and in vivo. Rabbit aortic rings were incubated with different concentrations of DDAVP using saline as control. The supernatant was assayed for 6-oxo-PGF1 alpha by radioimmunoassay. All concentrations of DDAVP gave a significant release of 6-oxo-PGF1 alpha. Vasopressin was much less potent. When DDAVP was infused into haemophilic patients there was a significant increase in circulating 6-oxo-PGF1 alpha levels immediately after the infusion. The facial flushing observed as a side-effect of DDAVP could therefore be prostacyclin-mediated. We confirmed this by abolishing the DDAVP induced flushing seen in normal subjects by prior treatment with aspirin which inhibits PGI2 formation.

There is evidence to suggest that platelet activation occurs in Raynaud's syndrome. We evaluated the effect of prostacyclin (PGI2) a potent antiplatelet and vasodilator agent in 5 female patients with Raynaud's syndrome. Outpatient visits were made at weekly intervals for 4 weeks. At the first visit buffer solution (Wellcome Laboratories) was infused intravenously for 5 hrs, thereafter three five hr infusions of PGI2 at a peak dose of 10 ng/Kg/min were given. Six weeks after the infusions patients were reviewed. Symptomatic improvement, including healing of ischaemic ulcers, occurred in 4 out of 5 patients. Thermography confirmed an increase in hand temperature after PCI2. Subjective and objective improvement has persisted for at least 6 weeks after the last treatment.

ADP, generated from red blood cells is believed to be responsible for the spontaneous aggregation of platelets in whole blood. This notion is based mainly on the use of enzymes which remove ADP. We have studied spontaneous platelet aggregation in whole blood and autologous platelet rich plasma obtained from 12 healthy male and female volunteers. Platelet aggregation was quantitated by measuring the fall in the number of single platelets counted using a whole blood platelet counter (Ultra Flo 100). In a rotating tube model, the mean fall in the number of platelets due to spontaneous aggregation was 56% in whole blood but, only 3% in platelet rich plasma prepared from the same blood samples. Spontaneous platelet aggregation in whole blood was unaffected by apyrase grade I, but was reduced to 15% by apyrase grade II, to 38% by creatine phosphokinase/creatine phosphate and to 9% by pyruvate kinase/phosphoenolpyruvate. The results of this study provide additional evidence that ADP generated in whole blood triggers the spontaneous aggregation of platelets.

By a method of counting single platelets in diluted whole blood, platelet aggregates were quantified ex-vivo. Four groups: 20 thrombotic patients, 10 non-thrombotic patients, 10 healthy old controls and 10 healthy young controls were included in the study. Using a 19 gauge needle, with and without tubing, venous blood was taken into buffered EDTA, as a disaggregating agent and buffered EDTA-formalin, as the fixative. The amount of platelet aggregates quantified was affected by the quality of venepuncture or the rate of blood flow through the needle, but was unaffected by the presence of the tubing. There was no statistically significant difference between the four groups, in terms of the platelet aggregates quantified, but scanning electron microscopy revealed the presence of irreversible aggregates, composed of platelet red and white blood cells, in the blood of a greater number of thrombotic patients than non-thrombotic or healthy controls. Platelet aggregates were also quantified in aliquots of platelet rich plasma, and were found to be significantly greater than the corresponding values in whole blood. The difference appeared to be due to increased viscosity of the plasma, induced by the fixative which reduces platelet mobility during centrifugation. It is concluded that the platelet aggregates which disaggregate in buffered EDTA may represent an artifact of blood collection; the irreversible aggregates are suspected to represent the in vivo circulating aggregates.

We have conducted a dose-ranging and feasibility study of daily subcutaneous injections of ancrod (Arvin) as a potential antithrombotic method in 28 patients following operation for fractured neck of femur. Sustained, predictable fibrinogen depletion during the first post-operative week was induced by four different regimes. A total dose of 10 units/kg weight, given in divided doses starting on the day of operation, is suggested as a possible antithrombotic regime. Ancrod treatment produced a rise in fibrinogen/fibrin degradation products, prolongation of the thrombin clotting time, and a fall in plasminogen, plasma fibrinogen and corrected blood viscosity were observed in 14 control patients. Plasma fibrinogen was correlated with plasma viscosity and corrected blood viscosity. No adverse effects of treatment occurred. Subcutaneous ancrod appears to be a simple, safe, and feasible potential antithrombotic method, and merits trials of efficacy in the prevention of post-operative thromboembolism.

Fibrinolytic shutdown may be important in the development of postoperative deep vein thrombosis (DVT). We have previously shown that stanozolol 50 mg, given intramuscularly 24 hr before surgery, prevents the decrease in plasminogen activator activity (PA) seen on the first postoperative day in patients at high risk of DVT. To investigate the role of fibrinolytic shutdown in causation of DVT, sixty patients were randomized in a double-blind controlled trial to receive stanozolol or placebo intramuscularly, and DVT was detected by leg scanning and confirmed by venography. Scan positive DVT occurred in 11 of 31 placebo patients (35%) and 12 of 29 who received stanozolol (41%). A significant decrease in PA was confirmed in the placebo group, while stanozolol caused a significant increase in PA on the first postoperative day. Patients in either group who did not develop DVT showed minimal changes in PA. We conclude that prevention of fibrinolytic shutdown by this regimen of stanozolol does not prevent postoperative DVT, and that further studies are required to clarify the relationship of postoperative fibrinolysis and DVT.

Venous oxygen tension (pO2) was measured in discrete samples of blood obtained through the femoral vein of cardiac catheterisation patients before, during and after application of sustained external graduated pressure in the form of compression stockings (T. E. D. Kendall). There was a significant reduction (p less than 0.05) of pO2 from the baseline value both 30 sec and one minute after the application of the pressure stockings. Thereafter, the pO2 rose to baseline values. Two minutes after the stockings were removed there was again a significant reduction (p less than 0.05) of pO2 from the baseline value. We suggest that the decrease in venous pO2 on application of external pressure may be a reflection of washing out of stagnant hypoxic blood from the venous valve pockets, which may be related to the formation of deep vein thrombosis (DVT).

In a randomised double-blind controlled trial 24 patients undergoing elective aortic bifurcation graft surgery received subcutaneous calcium heparin (2,500 u pre-operatively then 5,000 u 12-hourly for 7 days) and 25 control patients received saline injections. All patients received a routine dose of intravenous sodium heparin intra-operatively. The trial was terminated because of excess bleeding complications in patients receiving subcutaneous heparin (8 vs. 1, p less than 0.05). Deep vein thrombosis occurred in 6 control patients and 2 patients on heparin (p less than 0.05). In this group of patients undergoing major vascular surgery the risk of bleeding due to heparin outweighed the potential benefit of thrombotic prophylaxis.

We have previously shown abnormalities of haemostasis suggestive of intravascular coagulation in patients with malignant hypertension, a condition associated with retinopathy and renal fibrin deposition. To determine whether such abnormalities are specific to malignant hypertension, we have measured several haemostatic and haemorheological variables in 18 patients with malignant hypertension (Group 1), 18 matched healthy controls (Group 2), and 18 patients with non-malignant hypertension (Group 3) matched for renal pathology, blood pressure and serum creatinine with Group 1. Both Groups 1 and 3 had increased mean levels of fibrinogen, factor VIIIc, beta-thromboglobulin, plasma viscosity and blood viscosity (corrected for haematocrit); and decreased mean levels of haematocrit, antithrombin III and platelet count. Mean levels of fast antiplasmin and alpha2-macroglobulin were elevated in Group 1 but not in Group 3. We conclude that most blood abnormalities are not specific to malignant hypertension; are also present in patients with non-malignant hypertension who have similar levels of blood pressure and renal damage; and might result from renal damage as well as promoting further renal damage by enhancing fibrin deposition. However increased levels of fibrinolytic inhibitors in malignant hypertension merit further investigation in relation to removal of renal fibrin.

Baseline white blood cell count (WCC) and haematocrit were examined in relation to recurrent coronary events and to all-cause mortality in 2026 persons enrolled in the first Persantin-Aspirin Reinfarction Study (PARIS-1) 2-60 months after myocardial infarction. WCC was strongly related to coronary recurrence (relative risk 3.5 for men with WCC greater than or equal to 9 X 10(9)/l vs men with WCC less than 5 X 10(9)/l) and total mortality (relative risk 2.6). No such relationships were found for haematocrit. WCC correlated also with cigarette-smoking, diuretic use, serum cholesterol and uric acid; however, the associations with coronary recurrence and total mortality persisted on multiple linear and logistic regression analysis including these variables and treatment group (p less than 0.001). WCC is therefore an easily-measured prognostic variable in survivors of myocardial infarction. Furthermore, we suggest that white blood cells may promote myocardial ischaemia by capillary plugging and/or release of toxic oxygen metabolites.

Spontaneous platelet aggregation (SPA) was studied in human whole blood at 3, 5, 10, 20, 30, 40, and 60 minutes after venepuncture. Using a whole blood platelet counter, SPA was quantified by measuring the fall in single platelet count upon rollermixing aliquots of citrated blood at 37 degrees C. The extent of SPA increased with the time after venepuncture, with a correlation coefficient of 0.819. The inhibitory effect of dipyridamole (Dipy) on SPA was studied: (a) 10 microM at each time interval; (b) 0.5-100 microM at 3 and 30 minutes and (c) 15 microM in combination with 100 microM adenosine, 8 microM 2-chloroadenosine (2Clad, an ADP receptor blocker) and 50 microM aspirin. There was a rapid decrease in the inhibitory effect of Dipy with the time after venepuncture; the correlation coefficient was -0.533. At all the concentrations studied, Dipy was more effective at 3 minutes than at 30 minutes after venepuncture. A combination of Dipy with adenosine, 2ClAd or aspirin was a more effective inhibitor of SPA than either drug alone. However, when 15 microM Dipy and 10 microM Ad were added together, the inhibitory effect of Dipy was not increased significantly, suggesting that Dipy inhibits platelet aggregation independent of Ad. The increase in SPA with the time after venepuncture was abolished when blood was taken directly into the anticoagulant containing 5 microM 2ClAd. It is suggested that ADP released from the red blood cells is responsible for the increased platelet aggregability with the time after venepuncture and makes a serious contribution to the artifacts of in vitro platelet function studies.

Platelet aggregation and thromboxane A2 have been implicated in the pathogenesis of several forms of vascular disease. The aim of this study was to determine the effect of a wide range of adrenoceptor antagonists on platelet aggregation, and thromboxane A2 production, from normal human platelet rich plasma in vitro. Labetalol, pindolol and propranolol inhibited platelet aggregation to collagen in a dose dependent manner. Increasing the concentration of collagen "shifted" the dose response curve to the right. These 3 drugs also significantly inhibited thromboxane A2 generation in response to collagen but not to arachidonic acid. This effect was independent of any inhibitory effect of these drugs on platelet aggregation, and occurred at a drug concentration close to that obtained in vivo. Atenolol, metoprolol, prazosin and timolol were similarly assessed but had no effect on either platelet aggregation or thromboxane A2 generation. This ability of labetalol, pindolol, and propranolol to inhibit platelet aggregation and thromboxane generation, may be of clinical benefit in view of the increasing evidence implicating thromboxane A2 in the pathogenesis of vascular disease.

There is an increased frequency of arterial thrombosis in cigarette smokers. The changes in blood coagulation seen in these subjects have been studied by many workers but results have not always been in agreement. We wished to study the effects of acute smoking on platelet behaviour, fibrinolysis and haemorheology in ten habitual smokers, and to compare these results with non-smoking controls. Results show that the smoking group had higher plasma fibrinogen (p less than 0.04), lower plasminogen (p less than 0.02) and plasminogen activator (p less than 0.05), and higher plasma viscosity (p less than 0.003). The changes seen in cigarette smokers after smoking three cigarettes were an increase in the rate of platelet aggregation to ADP (p less than 0.02), an increase in alpha 2M, (p less than 0.02), and factor VIII RAG (p less than 0.05). Plasma viscosity was decreased (p less than 0.02) as was red cell deformability (p less than 0.02). We confirm an increased tendency to hypercoagulability in smokers compared to controls which becomes more pronounced immediately after smoking three cigarettes.

An episode of defibrination with bleeding following high dose Edinburgh Factor IX (D.E.F.IX) replacement in a patient with haemophilia B undergoing knee joint replacement is reported. We have also monitored plasma fibrinopeptide A levels in patients with haemophilia B following ten standard doses of D.E.F.IX (15-20 u/kg) and have been unable to document any change. Activation of the coagulation system, as previously noted, appears to be related to the use of Factor IX concentrates in high doses.

Platelet aggregation was studied at 37 degrees C in citrated whole human blood, using the Ultra Flo 100 Whole Blood Platelet Counter. Aggregation was measured as a fall in the number of single platelets following addition of an aggregating agent. At peak aggregation, the fall in the number of platelets induced by ADP (10 microM), collagen (1 microgram/ml) or thrombin (0.2 U/ml) was about 90%. When blood was incubated with the prostacyclin-analogue ZK36374, the aggregation responses to ADP, collagen and thrombin were reduced with IC50's = 0.5, 1.5 and 3 nM respectively and the corresponding IC100's were: 1, 3 and 12 nM. When ZK36374 was added at peak aggregation, the number of single platelets increased significantly due to disaggregation of preformed platelet aggregates. It is concluded that the present technique represents a rapid, sensitive and more physiological approach for investigating the effects of pharmacological agents on platelet aggregation.

Plasma levels of betathromboglobulin (BTG), fibrinopeptide A (FPA) and B beta 15-42 fragment, indices of platelet release, thrombin generation and plasmin activity respectively, were measured in 32 high risk patients during a double blind study of a single dose of the anabolic steroid stanozolol (50 mg IM) in the prevention of DVT after major gastro-intestinal surgery. The prevalence of malignancy and the incidence of DVT (125I fibrinogen scan) were similar in the two treatment groups. On the first postoperative day, BTG, FPA and B beta 15-42 levels were increased in most patients. Plasma BTG levels were significantly increased on the first post-operative day in patients who developed a DVT (n = 14) compared to those patients who did not (n = 18). A significant increase in FPA levels was found in the DVT group, 7 days after surgery. On the morning before surgery, plasma B beta 15-42 levels were significantly increased in patients who developed a DVT. In patients undergoing surgery for early malignancy (n = 17), we observed a pre-operative increase in FPA levels when compared to patients without malignancy. At post-operative day 7, B beta 15-42 levels were significantly increased in patients who received stanozolol (n = 15), when compared to the placebo group, suggesting that intramuscular stanozolol increases fibrinolysis in vivo.

Increased plasma levels of beta-thromboglobulin (beta TG) and fibrinopeptide A (FPA), markers of platelet release and thrombin generation respectively, were measured in normal women, women taking oral contraceptives, normal pregnancy and pregnant women with hypertension or pre-eclampsia. No significant increases in beta TG or FPA were found in women taking oral contraceptives. Significantly increased concentrations of beta TG, but not FPA, were found in normal pregnant women in the second and third trimester of pregnancy when compared with non-pregnant age-matched controls. In eleven women with pregnancy hypertension and thirteen women with pre-eclampsia significantly elevated levels of both beta TG and FPA were found when compared with age, parity and gestation-matched pregnant controls. Although the mean value for both beta TG and FPA in the group with pre-eclampsia was higher than the group with pregnancy hypertension, the difference was not statistically significant. These findings provide additional evidence that pre-eclampsia and pregnancy hypertension are associated with activation of the coagulation system and the platelet release reaction.

Prostaglandin E1 (PGE1) and prostacyclin have been used in Raynaud's phenomenon (RP) but are unstable and require intravenous administration. An alternative approach is to stimulate the body's own PGE1 production via administration of the precursor essential fatty acid. We studied the effect of 12 capsules/day of evening primrose oil (EPO) on the manifestations of RP. 21 patients received a two week course of placebo, thereafter 11 received EPO for 8 weeks and 10 patients received placebo. As the weather worsened the placebo group experienced significantly more attacks than the EPO group. Visual analogue scales assessing the severity of attacks and coldness of hands improved in the EPO group. No changes were seen in either group in hand temperatures and cold challenge plethysmography. Blood tests showed some antiplatelet effects of the drug. In conclusion patients receiving EPO benefited symptomatically. This was not matched however by any change in objective assessment of blood flow, although changes in platelet behaviour and blood prostanoids were observed.

Ketorolac is a potent cyclo-oxygenase inhibitor used for the treatment of postoperative pain. It is known to have anti-platelet properties. The aim of this study was to determine the effect of ketorolac on haemostasis both alone and in combination with low dose heparin in 12 healthy male volunteers. Each volunteer received the following drug combinations in a double blind, placebo controlled, cross over manner: ketorolac placebo/heparin placebo, ketorolac active/heparin placebo, ketorolac active/heparin active and ketorolac placebo/heparin active. Ketorolac significantly prolonged bleeding time, inhibited platelet aggregation to arachidonic acid and collagen and platelet thromboxane production. Heparin had no effect on bleeding time or platelet function, but significantly prolonged the kaolin cephalin clotting time and increased anti-Xa levels. Ketorolac had no effect on the kaolin cephalin clotting time or anti-Xa levels and no interaction was found between ketorolac and heparin in any of the investigations. The prolongation of bleeding time seen with ketorolac is unlikely, to be of any major clinical significance as almost all subjects remained within the normal range; however, it should be used with caution in subjects with haemostatic problems.

Blood viscosity and its major determinants (haematocrit, plasma viscosity and fibrinogen) as well as several haemostatic variables were measured in 21 patients with the nephrotic syndrome, and 21 controls matched for age, sex, smoking habit and serum creatinine. Blood viscosity was significantly increased in the nephrotic group, measured at a low shear rate (mean increase 41%, p less than 0.01) and at a high shear rate (mean increase 25%, p less than 0.01). Haematocrit was not significantly increased, but plasma viscosity was significantly higher (p less than 0.01), associated with increased plasma macroglobulins especially fibrinogen, which was increased to double the plasma concentration of the control group (p less than 0.01). Nephrotic subjects also had increased plasma levels of alpha 2-macroglobulin, factor VIII activity, factor VIII antigen and beta-thromboglobulin; differences in antithrombin III, fibrin degradation products, plasminogen, and platelet count were not significant. We suggest that increased blood and plasma viscosity may play a role in the vascular complications of the nephrotic syndrome.

Plasma levels of beta-thromboglobulin (BTG) and fibrinopeptide A (FPA), markers of platelet release and thrombin generation respectively, were measured in 48 patients within 3 days of admission to hospital for acute chest pain. Twenty-one patients had a confirmed myocardial infarction (MI); 15 had unstable angina without infarction; and 12 had chest pain due to noncardiac causes. FPA and BTG were also measured in 23 control hospital patients of similar age. Mean plasma BTG levels were not significantly different in the 4 groups. Mean plasma FPA levels were significantly higher in all 3 groups with acute chest pain when compared to the control subjects (p less than 0.01), but there were no significant differences between the 3 groups. Increased FPA levels in patients with acute chest pain are not specific for myocardial infarction, nor for ischaemic chest pain.

The treatment of haemophilia has been dramatically improved since the introduction of factor VIII and IX concentrates, however these concentrates have brought new problems such as hepatitis and A.I.D.S. An oral agent which could raise endogenous levels of factor VIII and IX would be of great benefit. Danazol, an anabolic steroid, has recently been shown to increase levels of factors VIII and IX in haemophilia. We therefore studied the effect of stanozolol, a closely related anabolic steroid, in 15 patients with haemophilia A or Christmas disease over a 2-4 week period. There was no consistent change in factor VIIIc or factor IX, and fibrinolysis was significantly enhanced. No effect was apparent on the incidence of spontaneous bleeds. However serum aminotransferases which were abnormal in 11 of the 15 patients at the start of the study fell significantly with stanozolol therapy. This raises the interesting possibility that anabolic steroids may be beneficial in patients with chronic liver diseases.

Activated protein C is a potent inhibitor of coagulation, and familial protein C deficiency has been associated with recurrent venous thrombosis. We have investigated protein C antigen levels in patients undergoing major elective abdominal surgery, to determine their relationships to postoperative deep vein thrombosis (DVT), malignancy, and preoperative treatment with intramuscular or oral stanozolol. Preoperative and postoperative protein C levels were not significantly different in patients with and without DVT (detected by 125I-fibrinogen leg scans), nor in patients with and without malignancy. In a placebo group (n = 26), a significant fall in protein C was maximal on the first postoperative day and persisted for 7 days. In a group given intramuscular stanozolol, 50 mg on the preoperative day (n = 23) stanozolol shortened the duration of the postoperative fall in protein C, but did not prevent DVT. In a group given oral stanozolol, 10 mg/day for 2 weeks before and 1 week after operation (n = 11), stanozolol significantly increased protein C levels prior to surgery, hence maintaining protein C at pretreatment levels after surgery. The effect of this regimen on the incidence of DVT is under study.