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Biomedical subjects

B J Britton

Publications and source records attributed to B J Britton.

17 recordsLinked to original sources
PubMed1990

Endoscopic sphincterotomy for the palliation of ampullary carcinoma.

Palliative endoscopic sphincterotomy was performed on 17 patients with adenocarcinoma of the ampulla of Vater. An endoprosthesis was inserted immediately after the sphincterotomy in four of the patients. Fourteen patients made uncomplicated recoveries from the procedure and their jaundice resolved completely. Early complications developed in three patients. One patient died from haemorrhage. Two patients, both of whom had an endoprosthesis, developed cholangitis. The endoprosthesis was removed and another inserted in one patient and the other underwent surgery. Both thereafter made uncomplicated recoveries. Jaundice subsequently recurred in eight patients and further endoscopic treatment was successful in five of these patients. Eleven patients died between 4 days and 23 months after the sphincterotomy with a median survival of 12 months. Four patients remain alive between 3 and 17 months after treatment. The results indicate that reasonable palliation can be achieved safely by endoscopic sphincterotomy.

Adenocarcinoma↗
PubMed1979

Effects of adrenergic blockade on plasma catecholamine levels during adrenaline infusion.

Alpha and beta adrenergic blocking drugs were administered, either singly or in combination, prior to a 3hr adrenaline infusion (2 microgram kg body wt-1 min-1)), Animals were premediated with either phenoxybenzamine (1 mg kg body wt-1 min-1). Phenoxybenzamine did not affect circulating adrenaline levels, but propranolol, either alone or in combination with phenoxybenzamine, resulted in a significant reduction in plasma adrenaline levels when compared with the control unblocked situation of adrenaline infusion without premedication. The results provide a possible explanation for the protective effect of combined adrenergic blockade in shock situations.

Animals↗
PubMed1977

Fibrinolytic, factor VIII and pulse rate responses to repeated adrenaline infusion followed by haemorrhage.

The role of catecholamines in the activation of coagulation and fibrinolysis following surgery remains controversial. In this study 5 dogs were infused with 1,2,3,6,9 and 12 microgram kg-1 min-1 of adrenaline at twice weekly intervals and were then reexposed to 3 microgram kg-1 min-1. Pulse rate and factor VIII increased after infusion of 1,2 and 3 microgram kg-1 min-1 but thereafter there was a diminished response and no response on reexposure to 3 microgram kg-1 min-1 although this was not significant in the case of pulse rate. Euglobulin lysis time shortened after each infusion of adrenaline and showed no development of tolerance. A control series of dogs infused with saline showed no similar changes. Both groups of animals were then bled to a blood pressure of 60 mm Hg for 60 minutes. Pulse rate and factor VIII did not change but euglobulin lysis time shortened in both groups. The results suggest that the activation pathways for changes in factor VIII and euglobulin lysis time induced by adrenaline are separate.

Animals↗
PubMed1977

Plasma catecholamine concentrations during operation.

Plasma catecholamines have been measured before, during and after operation in 40 patients undergoing elective major abdominal surgery and in 12 patients during open heart surgery. Plasma concentrations did not increase during abdominal surgery and showed only small increases during cardiopulmonary bypass. It appears that it is not possible to assess individual intra-operative sympatho-adrenal responses to surgical trauma by measurement of plasma catecholamine concentrations because of the efficiency of catecholamine uptake mechanisms.

Abdomen↗
PubMed1977

Effects of adrenoceptor blockade on plasma catecholamine levels during adrenaline infusion.

1. The present experiments investigate the effects of phenoxybenzamine and propranolol, singly and in combination, on plasma catecholamine levels in sheep receiving a three-hour adrenaline infusion. 2. Five groups of five anaesthetized sheep were studied for a period of 3 h each. One group acted as a control and received only a saline (0.9% w/v NaCl solution) infusion. A second group received a constant infusion of adrenaline (2 mug kg body weight-1 min-1). A third group received a similar adrenaline infusion, having been premedicated with phenoxybenzamine (1 mg/kg body weight). A fourth group recieved a similar adrenaline infusion following premedication with (+/-)-propranolol hydrochloride (7 mug/kg body weight). The fifth group received the adrenaline infusion following premedication with both the alpha- and beta-blocker in the above doses. 3. Plasma catecholamines were measured on blood samples taken at seven intervals before during and following the infusion. 4. Control animals receiving only a saline infusion remained physiologically and biochemically stable throughout the experimental period. 5. Adrenaline infusion in animals not receiving adrenoceptor blocking drugs caused a rise in plasma adrenaline levels from a low basal value of 1 mug/litre to a maximum level of 19.8 mug/litre. Animals premedicated with phenoxybenzamine exhibited a similar response. 6. Animals premedicated with propranolol before the infusion of adrenaline did not demonstrate as marked a rise of plasma adrenaline levels as the two previous groups. The maximum mean plasma adrenaline level recorded in this group was 6.88 mug/litre. 7. Animals premedicated with phenoxybenzamine and propranolol before the infusion of adrenaline showed only a small rise in plasma adrenaline levels compared with animals receiving adrenaline infusion alone. The maximum mean plasma adrenaline level in the group was only 3.43 mug/litre. 8. The studies demonstrate that by an unknown mechanism beta-adrenoceptor blockade with (+/-)-propranolol, either alone or in combination with phenoxybenzamine, lowers the plasma adrenaline response evoked by adrenaline infusion.

Animals↗
PubMed1976

The effect of beta adrenergic blockade upon exercise-induced changes in blood coagulation and fibrinolysis.

Exercise stress is known to stimulate blood coagulation and fibrinolysis possibly as a result of sympatho-adrenal stimulation of the beta adrenergic receptor. In order to test this hypothesis five men exercised on four separate occasions with and without prior beta adrenergic blockade with oxprenolol, propranolol and pindolol. The increase in plasma adrenaline and noradrenaline concentration was much greater during exercise under beta blockade but activation of fibrinolysis was enhanced as well. Factor VIII levels did not change significantly during any of the experiments. These results suggest that the activation of fibrinolysis by exercise is not mediated by the beta adrenergic receptor. The influence of beta adrenergic blockade on the change in factor VIII with exercise was inconclusive.

Adrenergic beta-Antagonists↗
PubMed1976

The coagulation and fibrinolytic response to splenectomy.

The responses of the coagulation and fibrinolytic systems in nine patients with Hodgkin's disease undergoing splenectomy and lymph node mapping have been compared with those in nine patients undergoing elective upper abdominal operation for benign conditions. Differences have been noted in base line levels of fibrinogen, prothrombin, partial thromboplastin time and euglobulin lysis time. Platelet count increases were exaggerated following splenectomy, but other parameters of coagulation activity behaved similarly in the two groups. There is no evidence from this study to support the suggestion that blood coagulability is increased more markedly following splenectomy than it is after other upper abdominal operations.

Abdomen↗
PubMed1975

Changes in blood catecholamine levels and blood coagulation and fibrinolytic activity in response to graded exercise in man.

Measurements of catecholamines, fibrinogen, factor VIII, thrombelastography, euglobulin lysis time and platelet adhesiveness have been carried out on venous blood obtained from normal males exposed to exercise on a bicycle ergometer at various work loads. Significant increases in adrenaline, factor VIII and fibrinogen were found only after exercise to exhaustion at 1500 kpm min-1 whereas the euglobulin lysis time was inversely proportional to the excercise load. There was no change in platelet adhesiveness. These findings support the results of studies using adrenaline infusions or adrenergic blockade which suggest that stress-induced increases in factor VIII are mediated via adrenergic stimulation but that activation of fibrinolysis is not dependent on adrenaline.

Adult↗