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Biomedical subjects

J Bevan

Publications and source records attributed to J Bevan.

32 records · Page 2Linked to original sources
PubMed1985

Inhibition by aspirin of human arterial and venous prostacyclin synthesis.

Prostacyclin (PGI2) synthesis by human mesenteric arteries and veins was measured ex vivo in 62 patients who received either no medication or a single oral dose of aspirin 40 mg, 75 mg or 300 mg approximately 24 hrs pre-operatively. Each dose of aspirin caused a significant reduction in both arterial and venous PGI2 synthesis compared with the untreated group. Arterial PGI2 synthesis did not differ significantly from venous PGI2 synthesis whether assessed by sample weight or sample area.

Administration, Oral↗
PubMed1983

Effects of ketanserin and mepyramine on platelet aggregation and on the uptake of 5-hydroxytryptamine into platelets.

We have determined the effects of ketanserin, a 5HT2 antagonist, and of mepyramine, a histamine H1 antagonist, on the aggregation induced in platelet rich plasma by 5-hydroxytryptamine (5HT), adenosine diphosphate (ADP), and by combinations of 5HT and ADP. Both ketanserin and mepyramine inhibited 5HT-induced aggregation and the 5HT component of the aggregation induced by combinations of 5HT and ADP. Both agents also inhibited the second phase of the aggregation induced by ADP alone but higher concentrations of the agents were required. On a molar basis, ketanserin was always a more potent inhibitor of aggregation than mepyramine. Ketanserin did not consistently inhibit the ADP-induced release reaction nor did it inhibit ADP-induced aggregation in aspirin-treated platelets that were unable to undergo a release reaction. The results suggest that 5HT2 receptors are involved in 5HT-induced aggregation and that the platelets' endogenous 5HT may contribute to the second phase of ADP-induced aggregation. We have also compared the effects of ketanserin and mepyramine on 5HT uptake into platelets. In this case mepyramine was a much more potent inhibitor than ketanserin. The different effectiveness of ketanserin and mepyramine as inhibitors of aggregation and 5HT uptake provides further evidence for different 5HT receptors for these two processes, and indicates that those involved in the 5HT uptake may be more akin to histamine H1 receptors.

Adenosine Diphosphate↗
PubMed1982

A regimen for low-dose aspirin?

The effects of different regimens of 40 mg aspirin on platelet thromboxane A2 synthesis and vascular prostacyclin synthesis were determined in patients who were undergoing elective surgery for removal of varicose veins. Aspirin 40 mg taken at intervals of 48 hours consistently reduced platelet thromboxane A2 synthesis to a level at which it failed to support platelet aggregation and the associated release reaction. This effect lasted for at least 36 hours. In contrast, aspirin 40 mg every 72 hours did not have the same consistent effect. Both dose regimens led to a reduction in vascular prostacyclin synthesis 12 hours after the last dose, but 36 or 72 hours after the last dose prostacyclin synthesis was not reduced; thus the inhibition of prostacyclin synthesis was short lived. If the balance between platelet thromboxane A2 and vascular prostacyclin synthesis is important in thrombosis 40 mg aspirin every 48 hours may have the maximum antithrombotic effect.

Adult↗
PubMed1981

Differential inhibition by low-dose aspirin of human venous prostacyclin synthesis and platelet thromboxane synthesis.

The capacity of venous tissue for prostacyclin synthesis was determined in 68 patients undergoing surgery for removal of varicose veins. A single dose of aspirin (81 mg or 300 mg) taken 14 h preoperatively strongly inhibited its synthesis, and the effect of 300 mg was still evident 48 h after ingestion. A single dose of 40 mg aspirin taken 14 h preoperatively had no effect on prostacyclin synthesis. The capacity of blood platelets to synthesise thromboxane (measured as malondialdehyde) was determined in volunteers before and at various times after ingestion of 300 mg or 40 mg aspirin. Both doses had an inhibitory effect that lasted for at least 96 h. The length of time for which the amount of thromboxane synthesised was insufficient to support platelet aggregation and the platelet release reaction depended on both the donor and the dose of aspirin. If prostacyclin and thromboxane are important in the pathogenesis of thrombosis, then doses of aspirin much lower than those used previously should be tested. The long-lasting effect of 300 mg aspirin on both venous tissue and platelets indicates that this dose is unlikely to produce a favourable prostacyclin/thromboxane balance.

Aspirin↗
PubMed1979

Eight years' experience with a weekday gynaecological ward.

Between 1971 and 1978, 9651 patients were admitted to a gynaecological ward in use five days a week. 39.5% of patients were admitted as "day cases", the rest as "overnight stay" patients. Patients can choose between local or general anaesthesia and between day care or overnight stay. The procedures carried out were termination of pregnancy (41.3%), laparoscopy (14.1%), minor gynaecological procedures (41.2%), and urological procedures (3.4%). Despite an 80% increase in work load during these 8 years the waiting list, which fell by 62% in the first year, has been maintained at that level. The advantages of having such a unit in a modern gynaecological service are discussed.

Abortion, Spontaneous↗
PubMed1979

Doctors on the move.

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Facility Design and Construction↗
PubMed1978

Default patterns of patients attending clinics for sexually transmitted diseases.

The influence of gender, propaganda, and treatment methods was studied in relation to default behaviour of patients with sexually transmitted diseases. The overall default rate of men and women was similar, but a larger proportion of men defaulted after the initial visit, while the biggest fall-out in women was after the second attendance at the clinic. The institution of a propaganda campaign was followed by a reduction in defaulting. The statistical significance of this is open to question, however: moreover the observed improvement in default rate was not maintained once the propaganda had been relaxed. Men treated for non-gonococcal urethritis by a regimen which included one injection a week for three weeks showed a highly significantly lower default rate compared with those who received tablets alone.

Counseling↗