Simulation model for planning renal services.
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Computer Simulation↗
Biomedical subjects
J N Barnes
Publications and source records attributed to J N Barnes.
Dihydrocodeine in renal failure: further evidence for an important role of the kidney in the handling of opioid drugs.
The pharmacokinetics of a single oral dose of dihydrocodeine were studied in nine patients with chronic renal failure treated by haemodialysis and nine subjects with normal renal function. In the patients the mean peak plasma dihydrocodeine concentration occurred later and the area under the curve was greater than in the normal subjects. Furthermore, the drug was still detectable after 24 hours in all the patients but only three of the normal subjects. These data, together with those obtained from previously published clinical case reports, contradict the traditional view that the body's ability to cope with opioid drugs is not altered in renal failure.
Adult↗
Effect of angiotensin converting-enzyme inhibition on potassium-mediated aldosterone secretion in essential hypertension.
1. Eight patients with essential hypertension were challenged with an infusion of 32 mmol of potassium chloride in saline before and after control of their blood pressure by the angiotensin converting-enzyme (ACE) inhibitor enalapril. 2. The potassium infusion was associated with similar increases in plasma aldosterone before and during enalapril treatment, although absolute aldosterone levels were lower after enalapril treatment despite higher plasma potassium levels. 3. The handling of the potassium load was altered by ACE inhibition. The area under the curve of a plot of the increase in plasma potassium above baseline against time was greater during enalapril treatment than during treatment with placebo. 4. These observations contrast with data obtained in the dog and demonstrate that in patients with essential hypertension stimulation of aldosterone secretion by potassium is not abolished by chronic suppression of plasma angiotensin II; and although plasma aldosterone remains at a lower level, the homoeostasis of plasma potassium is only mildly impaired.
Adult↗
The effect of acute beta-adrenoceptor blockade on examination performance.
Simple tests of verbal reasoning and mental arithmetic, taken under mildly stressful conditions, have been shown to give a reproducible test of intellectual function within groups of normal subjects. Using these tests, in two separate examinations, a double-blind cross-over study was performed on 35 medical students to assess the effects of acute beta-adrenoceptor blockade with propranolol on intellectual function. With placebo treatment, students recorded an average total score of 231.3 marks, with average scores of 108.9 marks on the mental arithmetic paper and 122.4 marks on the verbal reasoning paper. Treatment with propranolol was associated with an improvement in total score of 9.2 +/- 3.9 marks (P less than 0.05), an improvement in mental arithmetic score of 5.6 +/- 2.3 marks (P less than 0.05) and an improvement in verbal reasoning score of 3.6 +/- 2.4 marks (NS). Eighteen out of the 35 students said that they were mildly anxious before one examination and 13 students said they were anxious before both examinations. Those students who admitted anxiety seemed to benefit the most, in terms of improved examination performance, from treatment with propranolol.
Adrenergic beta-Antagonists↗
Effect of dialysate buffer on potassium removal during haemodialysis.
There is a linear relationship between potassium removal during haemodialysis and plasma potassium (Kp). Kp falls rapidly during the first hour of dialysis but very little during the last two hours of a five hour dialysis. There is a fairly constant movement of potassium from the intracellular to extracellular space throughout dialysis. Total potassium removal is best predicted by pre-dialysis Kp, but change in Kp is related to the impact of dialysis on acid-base status. The choice of acetate or bicarbonate buffered dialysate does not effect potassium removal during dialysis.
Acetates↗