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Biomedical subjects

C D Forbes

Publications and source records attributed to C D Forbes.

At least 199 records · Page 11Linked to original sources
PubMed1983

Contribution of the haematocrit to the bleeding time.

Bleeding time, platelet count and haematocrit were performed in 64 normal, anaemic and polycythaemic subjects with normal renal function and platelet counts over 100 X 10(9)/1. There was a significant inverse correlation between the bleeding time and haematocrit (r = -0.47) and an inverse correlation of the haematocrit and platelet count (r = -0.46). We suggest that the effect of the haematocrit on the bleeding time could explain the shorter bleeding time in men compared to women, and the shorter bleeding time in subjects with arterial disease, in whom an increased haematocrit is commonly found.

Adult↗
PubMed1983

Comparison of cerebral blood flow after venesection of bronchitic secondary polycythaemic and primary polycythaemic patients.

Cerebral blood flow was measured before and after lowering of haematocrit in four patients with primary polycythaemia and in nine with polycythaemia secondary to chronic obstructive airways disease. Cerebral blood flow values in each group were abnormally low to a similar degree at the start of the study and the degree of rise in cerebral blood flow per unit fall in haematocrit after venesection also was similar in each. Oxygen delivery fell despite increased cerebral blood flow and symptomatic benefit was infrequent. In male secondary polycythaemic patients rise in cerebral blood flow was not associated with any improvement in hypothalamo-pituitary-testicular function which we had previously noted to be suppressed in such hypoxic subjects. Our findings suggest viscosity changes rather than alteration in blood oxygen carriage to be responsible for cerebral blood flow improvement. It is concluded that therapeutic venesection in such patients should be applied with caution.

Adult↗
PubMed1983

Total knee arthroplasty in haemophilic arthritis.

The results of total knee replacement in five patients aged between 22 and 37 with severe haemophilia A or B are described. All patients had been managed conservatively without success. Frequent bleeds, severe pain and limitation of movement were the indications for operation. Despite close haematological surveillance, bleeding problems occurred in three of the patients and large quantities of plasma concentrates were required. Review of the patients over a period of 25 to 48 months after operation showed dramatic lessening of pain and maintenance of a satisfactory range of movement. The frequency of haemarthrosis diminished markedly and the requirements for factor concentrate in the years after operation fell substantially. Two patients returned to employment. Total knee replacement led to marked clinical improvement in all the patients, but the long-term results are not yet known.

Adult↗
PubMed1983

Blood viscosity in proliferative diabetic retinopathy and complicated retinal vein thrombosis.

Forty-two patients with longstanding retinal vein thrombosis and 36 patients with diabetes had their blood viscosity levels measured. In both conditions blood viscosity, plasma viscosity, and plasma fibrinogen levels were significantly higher in those patients with capillary non-perfusion and/or new vessels on fluorescein angiography, compared to those patients without these complications. The possible role of abnormal blood viscosity in producing capillary non-perfusion and its sequelae in both conditions is discussed.

Aged↗
PubMed1983

Bronchial carcinoma in von Willebrand's disease. Successful removal after hemostasis with lyophilized cryoprecipitate.

A man with severe von Willebrand's disease who had hemoptysis was followed-up for 2 1/2 years for continued hemoptysis and was discovered to have a bronchial carcinoma. Under close hematological surveillance, an uncomplicated pneumonectomy was performed, using a new factor VIII product--freeze-dried cryoprecipitate. This case illustrates that hemoptysis in von Willebrand's disease cannot always be attributed to the disease itself: that continued hemoptysis requires regular bronchoscopy and that major surgery can be performed in von Willebrand's disease with effective correction of the coagulation defect using freeze-dried cryoprecipitate.

Bronchial Neoplasms↗
PubMed1982

Haemophilia and the kidney: assessment after 11-year follow-up.

Radiological and biochemical investigations of renal function were performed in 57 patients with haemophilia, 27 of whom had been previously investigated in 1969. Although one-third of patients had a renal radiographic abnormality, only two had abnormalities persisting since 1969 and attributable to renal bleeding. Isotope renography was a sensitive indicator of renal abnormality whereas a history of haematuria was a poor discriminator for patients with abnormal intravenous urograms or impaired creatinine clearance. Haematuria was not associated with progressive loss of renal function and its natural history in haemophilia is probably benign.

Adolescent↗
PubMed1982

Effects of growth hormone, glucose and insulin on the factor VIII complex.

The relationship of growth hormone (GH) to the factor VIII complex (VIIIC, VIIIRAg and VIIIRRCo) was investigated. No correlation between basal levels of GH and factor VIII assays was found in 23 subjects. No significant change in factor VIII assays was observed after GH suppression by oral glucose or bromocriptine. After insulin-induced hypoglycaemic all three factor VIII assays rose and fell in parallel with GH. However, after exercise the rise in VIIIC and VIIIRAg preceded the rise in GH; and no changes in factor VIII assays were observed after administration of thyrotrophin releasing hormone (TRH) (releasing endogenous GH) or exogenous GH. These findings do not support a role for GH in the regulation of plasma levels of VIIIC, VIIIRAg or VIIIRRCo.

Antigens↗
PubMed1982

The effect of intramuscular stanozolol on fibrinolysis and blood lipids.

The effects of a single 50 mg intramuscular injection of the anabolic steroid stanozolol (Stromba) on fibrinolysis, blood coagulation and lipids was evaluated in 12 healthy male volunteers. Significantly increased plasminogen activator levels (p less than 0.05) was noted 24 hours following the injection and these remained elevated for one week. Plasminogen levels increased significantly by day two (p less than 0.01) and remained elevated for three weeks. HDL cholesterol fell (p less than 0.01) and both total and LDL cholesterol increased (p less than 0.05) when measured one month post injection. Stanozolol appears to have therapeutic potential as an activator of the fibrinolytic system when given by intramuscular injection.

Adult↗
PubMed1982

Factor IX thrombogenicity: in vivo effects on coagulation activation and a case report of disseminated intravascular coagulation.

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.

Adult↗
PubMed1982

DDAVP stimulates prostacyclin production.

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.

Animals↗
PubMed1982

Beta-thromboglobulin and platelet counts - effect of malignancy, infection, age and obesity.

Plasma levels of beta-thromboglobulin (BTG) and platelet count were studied in 69 control subjects, 19 patients with operable abdominal malignancy, and 9 patients with acute bacterial infection. In control subjects there was a significant rise in BTG and fall in platelet count with age, and a negative correlation of BTG with obesity. BTG and platelet count were normal in patients with operable malignancy, but significantly increased in patients with acute bacterial infection. These effects must be considered in studies of BTG and thrombosis.

Adult↗
PubMed1982

Increased blood viscosity and fibrinolytic inhibitor in type II hyperlipoproteinaemia.

Blood rheology and several haemostatic factors were studied in patients with type II hyperlipoproteinaemia (HLP) and matched controls. HLP patients had increased blood viscosity (p less than 0.01), the mean level being 18% higher at a low shear-rate (0.94 s-1) and 13% higher at a high shear-rate (94 s-1). The increased viscosity was due partly to a raised haematocrit (p less than 0.05), and partly to increased plasma viscosity (p less than 0.01) associated with increased plasma fibrinogen (p less than 0.02). Red cell deformability was normal, and viscosity was unrelated to either lipid or lipoprotein concentrations. Levels of the major fibrinolytic inhibitor. alpha 2-antiplasmin, measured by both functional and immunological techniques were higher in HLP patients (mean increase 30-32%). Plasminogen activator levels were normal in HLP patients and the ratio of fibrinolytic inhibitor to activator was therefore increased. Plasminogen concentrations were also increased. Levels of factor VIII activity and antigen, antithrombin III and anti-factor Xa activity, alpha 2-macroglobulin, platelet count, and platelet aggregation by adenosine diphosphate and adrenaline did not differ significantly in HLP patients and controls. These results suggest that the premature arterial disease associated with HLP may be related to increased blood viscosity, which reduces arterial blood flow, and increased alpha 2-antiplasmin, the major inhibitor of fibrinolysis.

Adolescent↗
PubMed1982

Plasma fibrinopeptide A and beta-thromboglobulin in pre-eclampsia and pregnancy hypertension.

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.

Beta-Globulins↗
PubMed1982

Prediction and selective prophylaxis of venous thrombosis in elective gastrointestinal surgery.

Clinical features were noted and routine and non-routine laboratory variables were measured before elective major gastrointestinal surgery in 63 patients aged 40 years or more. Deep-vein thrombosis (DVT), detected by routine 125I-fibrinogen leg scanning, developed in 21 patients. Five clinical variables but no laboratory variables were significantly associated with DVT: age; percent mean weight for age, sex, and height (%MW); presence of varicose veins; cigarette-smoking; and sex. The most useful discriminant index of these variables was age in years plus 1.3 x %MW. The index was validated prospectively in a further 41 patients, in 18 of whom DVT developed. The value of the index in selective prophylaxis was then assessed in a further 40 patients, of whom 24 (60%) with high-risk index received low-dose heparin (5000 units twice daily). DVT developed in 4 of the 40 patients, an incidence of 10% compared with the incidence of 37.5% (39 of 104) in the earlier studies with no prophylaxis.

Adult↗
PubMed1982

Effects of the non-selective beta-adrenoceptor blocking agent, carteolol, on platelet function, blood coagulation and viscosity.

We have studied the effect of a new beta-adrenergic blocker, carteolol, on platelet function, blood coagulation and viscosity in 10 healthy male volunteers. Following carteolol (5 mg orally) we were able to demonstrate significant inhibition of platelet aggregation to ADP (p less than 0.05) and adrenaline (p less than 0.01) after 5 hours, but not at 2 or 24 hours. This maximum inhibition of platelet aggregation corresponded to peak plasma concentrations of carteolol measured. The platelet release reaction, as measured by plasma levels of the platelet specific protein beta-thromboglobulin (BTG) was unaltered and there was no significant effect on a panel of coagulation tests or on blood viscosity.

Adenosine Diphosphate↗