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Biomedical subjects

D N Baron

Publications and source records attributed to D N Baron.

At least 37 records · Page 2Linked to original sources
PubMed1986

Action of compounds with effective in vivo mineralocorticoid activity on ion transport in leucocytes.

We have studied the in vitro short-term effects of aldosterone (1.0-1000 nmol l-1), cortisol (0.5-5.0 mumol l-1), fludrocortisone (1.0-10 nmol l-1) and carbenoxolone (0.5-3 mmol l-1) on 86rubidium influx (a model for potassium), 22sodium efflux, and [3H]-ouabain binding capacity in intact human leucocytes. No effect of aldosterone (at concentrations present in Conn's syndrome) or fludrocortisone could be demonstrated on cation fluxes or [3H]-ouabain binding compared to controls. No significant effect of cortisol, at concentrations either physiological or present in Cushing's syndrome, could be demonstrated on cation fluxes or [3H]-ouabain binding compared to controls. Carbenoxolone significantly increased 86Rb influx and 22Na efflux at concentrations known to cause hypokalaemia in man. The effect was not blocked by propranolol. No effect could be demonstrated for [3H]-ouabain binding.

Aldosterone↗
PubMed1986

Harmonizing multiple choice question marks with essay marks.

Many examinations contain both a multiple choice question (MCQ) section, which has wide-marking and is often norm-based, and an essay or other section which is criterion-based and often close-marked. The necessary addition or averaging of the marks is unsatisfactory without adjustment. We propose a procedure that adjusts the MCQ marks to the essay marking scale by equating the interquartile ranges of the two sets of marks.

Education, Medical↗
PubMed1986

Wellcome lecture 1986. Ideas towards a general theory of clinical biochemistry.

Clinical biochemistry, as an independent discipline within medical science, has developed its own body of theory and practice, and as such it cannot only be concerned with collecting observations. A simple report (plasma potassium = 5.3 mmol/L) is used as a model to discuss the problems of understanding measured chemical changes in the body in disease, and how these lead towards a general theory. These include the nature of the analysand and the reference base; accuracy and identification of the analyte; how disturbances of the steady state contribute to changes in a static result; the implications of precision; differences between activity, concentration and content; the convention of arithmetical concentration; and the meaning of 'abnormal', and of derived terms such as 'predictive value' and 'decision level'. Clinical biochemists/chemical pathologists, with their understanding of all these and related problems, must act as the necessary bridge between analysts and clinicians.

Chemistry, Clinical↗
PubMed1985

Hypoalbuminaemic hyponatraemia: a new syndrome?

Six patients with severe hyponatraemia had neurological features of hyponatraemia and pronounced hypoalbuminaemia. All had biochemical features typical of the syndrome of inappropriate secretion of antidiuretic hormone with low serum osmolality and an inappropriately high urinary osmolality. All were given infusions of whole plasma or albumin solution, or both, to restore their plasma albumin concentrations to normal, which led to a dramatic increase in plasma sodium concentrations and serum osmolality, with a concomitant fall in urinary osmolality in all patients. Neurological features were reversed in four patients. It is suggested that severe hypoalbuminaemia is an important cause of appreciable hyponatraemia; infusions of plasma and albumin in such patients may reverse the biochemical and clinical features and should form the basis of management.

Aged↗
PubMed1985

Sodium-potassium-ATPase activity in the dorsal root ganglia of rats with streptozotocin-induced diabetes.

Sodium-potassium-ATPase activity was measured in excised dorsal root ganglia of streptozotocin-diabetic rats, 2 months after induction of diabetes. In comparison with age-matched controls, there was a decrease in both the total and ouabain-insensitive activity, indicating an overall reduction in ouabain-sensitive activity of 46%. This decrease may explain the reduced amino-acid uptake exhibited by diabetic sensory ganglia and could be relevant to the development of diabetic neuropathy.

Animals↗
PubMed1985

Optimal conditions for measurement of Na+,K+-ATPase activity of human leucocytes.

The Na+,K+-ATPase activity of human leucocytes was assayed by measuring the release of inorganic phosphate (Pi) from ATP. The maximum enzyme activity was achieved under the following conditions: concentration (mmol/l), Tris/HCl 50, Na 100, K 15, ATP 5, Mg 7, EDTA 1; pH 7.2 and temperature 37 degrees C, were optimal. Ouabain showed maximal inhibition at a concentration of 10-100 mumol/l. Ethanol, the solvent for ouabain, had a dose-related inhibitory effect. Heparin or citrate used as an anticoagulant gave similar results. Leucocyte samples could be stored at -20 degrees C for up to 6 days without loss of activity. Hypotonic lysis had advantages over sonication as the technique for cell disruption. The leucocyte Na+,K+-ATPase enzyme activity in healthy subjects was 186 mumol of Pi h-1g-1 of protein (median) with a range 136-243 mumol of Pi h-1g-1 of protein. The within-batch coefficient of variation was 6.4% and the between-batch precision was 9.6%.

Buffers↗
PubMed1985

Adrenaline and ion flux in isolated human leucocytes.

Hypokalaemia may be produced in man by intravenous adrenaline infusion, or as a result of pathological disturbances which have led to a high plasma adrenaline concentration. With isolated human leucocytes used as a cellular model, adrenaline at concentrations at and above 9 nmol/l increases the influx of rubidium (a model for potassium flux) into cells, with a simultaneous efflux of sodium. There is no effect on Na+,K+-ATPase activity in lysed leucocytes. Use of the adrenoceptor blockers timolol and atenolol shows that the demonstrated effect of adrenaline on coupled active transport of ions is mediated by beta 2-adrenoceptors.

Atenolol↗
PubMed1985

Radial presentation of results of blood acid-base analyses.

Both students and clinical users find interpretation of blood acid-base numerical values to be difficult. A radial plot provides patterns which are easy to understand, and which can be applied to many groups of laboratory results.

Acid-Base Imbalance↗
PubMed1984

Sodium content of injectable beta-lactam antibiotics.

Many users of antibiotics are unaware of their ionic content. The ionic content is a particularly important factor for injectable beta-lactam compounds in patients on a restricted sodium intake. A table of the sodium content of commonly prescribed beta-lactam compounds is provided.

Anti-Bacterial Agents↗
PubMed1983

Leucocyte superoxide dismutase in rheumatoid arthritis.

Superoxide dismutase (SOD) activity was measured in polymorphonuclear leucocytes (PMNLs) and mononuclear cells (MNCs) from 60 patients with rheumatoid arthritis (RA) and in 15 controls. In all patients and controls SOD activity (U/mg protein) in MNCs was twice that in PMNLs. SOD activity in PMNLs and in MNCs from patients with RA was significantly higher than that in controls. SOD activity in PMNLs (but not in MNCs) from patients treated with corticosteroids was significantly higher than that from patients treated with nonsteroidal anti-inflammatory drugs. There was no relation between SOD activity in both PMNLs and MNCs and either the patients' age, sex, duration of disease, serum immunoglobulin concentration, IgM rheumatoid factor, and copper level, or the degree of disease activity.

Adult↗
PubMed1983

Serum copper: a marker of disease activity in rheumatoid arthritis.

Serum copper concentrations were measured in patients with rheumatoid arthritis (RA), ankylosing spondylitis (AS), osteoarthritis (OA), and in healthy controls. Median serum copper concentrations were raised significantly in RA and AS, but not in OA. Serum copper in RA correlated significantly with a number of disease activity markers--for example erythrocyte sedimentation rate (ESR), C-reactive protein, haemoglobin concentration, morning stiffness, and grip strength. It also correlated well with the overall disease activity as assessed by a composite index. Raised serum copper was associated with severe RA as manifested by the presence of immunoglobulin M rheumatoid factor, extra-articular features, weak grip and highly active disease. High serum copper might be related to the development of the pathological lesions observed in RA and not just be a secondary response.

Adult↗