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Biomedical subjects

F E Preston

Publications and source records attributed to F E Preston.

At least 217 records · Page 12Linked to original sources
PubMed1982

Relationship between platelet aggregation, thromboxane synthesis and albumin concentration in nephrotic syndrome.

Increased platelet aggregability on stimulation with sodium arachidonate (NaAA), collagen and ADP was found in a group of 14 patients with nephrotic syndrome when compared with age and sex matched controls. Five of the group also exhibited spontaneous platelet aggregation (SPA), associated with synthesis of thromboxane B2 (TxB2), and which appeared to correlate with a markedly increased serum triglyceride concentration. Thromboxane B2 generation in response to NaAA was increased and reflected both the low serum albumin concentration and the platelet aggregation response to this agent. Addition of albumin in vitro decreased the amount of TxB2 generated for a given dose of NaAA and increased NaAA and collagen-induced platelet aggregation thresholds. However, albumin had no significant effect on collagen-induced TxB2 production. The results suggest that the hypoalbuminaemia and associated reduced binding of arachidonic acid and increased synthesis of TxA2 account in part for the increased platelet aggregability seen in the nephrotic syndrome but that other mechanisms are also involved.

Adenosine Diphosphate↗
PubMed1981

Inhibition of prostacyclin and platelet thromboxane A2 after low-dose aspirin.

To compare the inhibitory effects of aspirin on prostaglandin synthesized by vessel walls and platelets, we obtained vein segments from five subjects before they were given 150 or 300 mg of aspirin and at various intervals afterward. We then measured prostacyclin (PGI2) synthesis with a radioimmunoassay for its stable metabolite, 6-keto-prostaglandin F1 alpha. Platelet production of thromboxane A2 was measured with a radioimmunoassay for its stable metabolite, thromboxane B2. Two hours after aspirin had been given, 81 to 100 per cent inhibition of PGI2 synthesis was demonstrated; 86 per cent inhibition was still evident in one subject tested eight hours after administration. Simultaneously, platelet production of thromboxane B2 was completely inhibited for more than 24 hours. We conclude that there is little difference between the initial inhibitory response of platelet cyclooxygenase and that of vessel-wall cyclooxygenase to these doses of aspirin. Our results also indicate that in male subjects the prolonged template bleeding time after aspirin is not the consequence of selective inhibition of platelet production of thromboxane.

Adult↗
PubMed1981

Acute hereditary tyrosinaemia type I: clinical, biochemical and haematological studies in twins.

Affected twins with acute hereditary tyrosinaemia type I are described. Attempts at therapy with a phenylalanine-tyrosine-methionine restricted diet supplemented with cysteine, vitamin E and ascorbic acid failed to influence the course of the disorder. The bleeding diathesis was due to a morbid reduction of a number of clotting factors, particularly factor VII, and this was associated with impaired platelet aggregation and release. The liver of one showed a marked reduction in fumarylacetoacetate lyase activity and her urine contained a potent inhibitor of red cell delta-aminolaevulinic acid dehydratase. Biochemical investigations of cultured fibroblasts suggest that these do not express the disorder and are unlikely to prove useful diagnostically.

Acetoacetates↗
PubMed1981

Gangrene of the toes with palpable peripheral pulses.

Thirty-five patients with gangrene or pregangrene of the feed associated with palpable peripheral pulses have been treated with the platelet suppressive drugs aspirin and dipyridamole. Sulphinpyrazone was substituted for two patients who could not tolerate aspirin. Complete reversal of the signs and symptoms occurred in more than 50% of the treated patients. Recurrence of pain occurred in the five patients in whom antiplatelet therapy was discontinued. Reversal of symptoms was again achieved by reintroduction of the drugs. An increased incidence of spontaneous platelet aggregation and hypersensitive platelets was observed in those patients who responded to platelet suppressive therapy. These results indicate that platelet suppressive therapy is of therapeutic value in selected patients with peripheral gangrene.

Aged↗
PubMed1981

Tentative protocol for the evaluation of coagulometers, based on one-stage prothrombin time.

Information on performance is invaluable to those who have to decide on the choice of an instrument. More interest is being shown in the use of coagulometers. Accordingly, a tentative protocol for the evaluation of coagulometers is presented for discussion. While it is based on the use of one-stage prothrombin time, principles of evaluation are laid down which should make it generally applicable. It is hoped that the tentative protocol will form the basis of a reference protocol and to this end comments are invited from users of coagulometers and suppliers. Comments for publication may be sent to the Editor of Clinical and Laboratory Haematology or to the Secretary of the Working Party.

Blood Coagulation Tests↗
PubMed1980

Evidence against vitamin K deficiency in normal neonates.

Umbilical cord plasmas from 24 normal full-term neonates were studied. We confirmed the prolonged prothrombin time and low levels of Vitamin K dependent clotting factors previously described (1), but using a number of recently developed immunological and coagulation techniques we could find no evidence of vitamin K deficiency. We conclude that the decreased levels of vitamin K dependent clotting factors of normal neonates are the result of decreased synthesis by the immature liver and that it is questionable whether vitamin K prophylaxis is necessary for these infants.

Blood Coagulation Factors↗
PubMed1980

Effect of dichloromethylene diphosphonate in Paget's disease of bone and in hypercalcaemia due to primary hyperparathyroidism or malignant disease.

30 patients with disorders of calcium metabolism were treated with dichloromethylene diphosphonate (C1(2)MDP, or clodronate disodium), an inhibitor of bone resorption. 13 patients with Paget's disease of bone were given C1(2)MDP by mouth (1.6 g/day). Serum-alkaline-phosphatase and urinary hydroxyproline fell to normal or near-normal within 3-7 months, and there was a clinical improvement in all but 1 patient. C1(2)MDP (0.8-3.2 g/day) also reduced plasma-calcium and urinary calcium in 17 patients with hypercalcaemia due to primary hyperparathyroidism or secondary to malignant disease. C1(2)MDP seems to be an effective oral drug for inhibiting excessive bone resorption in man.

Alkaline Phosphatase↗
PubMed1979

Thrombocytosis, circulating platelet aggregates, and neurological dysfunction.

In 12 patients whose neurological dysfunction was associated with thrombocytosis or evidence of abnormal platelet activation, or both, correction of the platelet disorder corresponded with reversal of the neurological symptoms. This suggests that platelet abnormalities may, in certain cases, produce several syndromes of neurological dysfunction, presumably as a result of obstruction of the cerebral microcirculation.

Adolescent↗
PubMed1978

Percutaneous liver biopsy and chronic liver disease in haemophiliacs.

Systematic screening of forty-seven haemophiliacs in Sheffield revealed abnormal liver-function tests in thirty-six (77%), with a tendency for these abnormalities to persist. To assess the importance of these abnormalities, percutaneous liver biopsy was carried out on eight symptom-free patients under factor-VIII cover. A wide spectrum of chronic liver disease was demonstrated, including chronic aggressive hepatitis and cirrhosis. The liver pathology bore no relation to clinical history or to biochemical findings. Hepatitis-B-virus markers were common, but evidence suggests that this is not the only factor contributing to the development of liver disease. The high incidence of chronic liver disease seems to be a recent development and is probably related to factor-concentrate replacement therapy.

Adult↗