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Biomedical subjects

D F Evans

Publications and source records attributed to D F Evans.

At least 91 records · Page 5Linked to original sources
PubMed1981

Effect of some i.v. anaesthetic agents on canine gastrointestinal motility.

Thiopentone 20 mg kg-1, ketamine 8 mg kg-1 and minaxolone 2 mg kg-1 were administered to fasting greyhound dogs. Mechanical and electrical activities from stomach, duodenum, jejunum and ileum were recorded using strain gauge force transducers and implanted bipolar electrodes. Thiopentone and minaxolone caused intense activity in the duodenum and jejunum (phase I and phase II of the interdigestive cycle), but not the stomach or ileum. The activity following injection of thiopentone or minaxolone was prevented by premedication with either atropine 0.05 mg kg-1 or pentolinium 0.2 mg kg-1. Ketamine had no influence on gastrointestinal activity or the response to thiopentone or minaxolone. None of these drugs altered the basal electrical rhythm of the intestine.

Action Potentials↗
PubMed1981

The use of cooled irrigating fluid for transurethral prostatic resection.

Forty patients selected for transurethral prostatic resection (TUR) were randomly allocated to one of 2 groups. Irrigating fluid used in the first group of 20 patients was cooled to a constant 8 degrees C; in the second group fluid at ambient temperature was used. Measurements were made of the volume of irrigating fluid used and haemoglobin loss during and after operation; the weight of resected tissue and its histological appearance were also studied. The core temperature of each patient was monitored throughout the operation. Significantly less irrigating fluid was used in the group receiving cooled fluid. Although per-operative and post-operative haemoglobin loss was also markedly reduced in this group, the difference failed to achieve statistical significance. The clarity of the operative field was considerably improved by the use of cooled fluid.

Hemoglobins↗
PubMed1980

Dose beta-blockade affect surgical performance? a double blind trial of oxprenolol.

Heart rates of surgeons rise when they carry out operations and this rise is abolished by beta-blockade. In an assessment of the effect of oxprenolol on surgical performance a group of surgeons took double blind either oxprenolol 40 mg or a matching placebo. Oxprenolol abolished increases in heart rate (P < 0.001) but had no effect on a profile of performance test assessing tremor, suturing accuracy and co-ordination. Reaction time of the surgeons was significantly slowed by oxprenolol (P < 0.01). Using a self-administered visual analogue scoring system the surgeons recorded no subjective changes in mood after beta-blockade and were surprisingly unaware of whether they had taken oxprenolol or placebo.

Attention↗
PubMed1979

Diabetic impotence: studies of nocturnal erection during REM sleep.

Nocturnal erections were studied in 30 diabetic patients who complained of impotence and in 11 healthy volunteers. The maximum increase in penile circumference was measured by a penile strain-gauge and recorded on a portable tape-recorder; an external oculogram was recorded simultaneously to identify periods of rapid-eye-movement sleep. The technique gave reproducible results, was acceptable to patients, and was suitable for use in an oridnary hospital ward. Only six diabetics showed a maximum increase in penile circumference of under 15 mm, whereas all but one of the healthy subjects showed maximum increases above this value. Of the six diabetics, five complained of total impotence and had other features of autonomic neuropathy that suggested an organic basis for their impotence. The other patient complained of partial importence, which was probably caused by psychological factors. These findings suggest that the prevalence of organic impotence among diabetics has been overestimated.

Diabetes Complications↗
PubMed1978

Heart-rates of surgeons during operations and other clinical activities and their modification by oxprenolol.

The heart-rates of surgeons were recorded by ambulatory monitoring methods while they operated and while they conducted surgical outpatient clinics. Heart-rates during operations were also monitored 1 hour after the surgeons had taken an oral dose of 40 mg oxprenolol. During operations the mean heart-rate of 8 surgeons was 121/min with maximum rates in some cases of over 150/min. The tachycardia was abolished by 40 mg of oxprenolol which reduced heart-rates during operations to below those recorded during surgical outpatient clinics. Physical work necessary to reproduce the mean heart-rate whilst operating could not be sustained for more than 10--15 min.

Depression, Chemical↗
PubMed1978

Cholesterol monohydrate growth in model bile solutions.

The growth of cholesterol monohydrate from solutions of bile salt, lecithin, and small electrolytes has been studied by microscopy and with the Coulter Counter. The crystal forms found by microscopy are the same as those seen in human gallstones and in squirrel monkey cholesterol microliths. The cholesterol growth rates determined with the Coulter Counter vary slowly with cholesterol concentration at low degree of supersaturation but become exponential at higher cholesterol concentrations. Growth is accelerated by the presence of calcium and magnesium but inhibited by potassium. These results can be combined with previous measurements of cholesterol dissolution rates to give a more accurate picture of the dynamics of gallstone formation.

Bile↗
PubMed1975

Diffusion in bile and its implications on detergency.

Diffusion coefficients of bile salts, lecithin, and cholesterol above the critical micelle concentration have been measured with the diaphragm cell at varying concentrations of bile salts, lecithin, and added electrolyte. The diffusion of the bile salt can be five times faster than that of the solubilized lipids. This is shown not to be an artifact of multicomponent diffusion, but a result of a different transport mechanism of the bile salt. As a consequence, the concentration of bile salt and lipids at the surface of a cholesterol gallstone can differ from those in the bile solution. The effects of this upon growth and dissolution in detergent solutions are discussed.

Bile Acids and Salts↗
PubMed1974

Accelerating gallstone dissolution.

The dissolution rates of cholesterol in model bile salt solutions are controlled by diffusion in slowly flowing bile and by interfacial kinetics in rapidly flowing bile. At low flow, dissolution varies with the square root of bile flow and can be predicted, a priori, from existing correlations of mass transfer. At high bile flow, dissolution is independent of bile flow and is probably dominated by the rate of micelle adsorption. These results show that cholesterol gallstone dissolution, a potential nonsurgical therapy for cholelithiasis, can be accelerated little in slow bile, but more significantly in rapidly flowing bile.

Bile↗