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Biomedical subjects

R J Simpson

Publications and source records attributed to R J Simpson.

At least 379 records · Page 21Linked to original sources
PubMed1983

Isolation and complete amino acid sequence of a basic low molecular weight protein from black swan egg white.

The following complete amino acid sequence of a low molecular weight basic protein (Mr 4,454) from black swan egg white has been determined: less than Glu-Val-Arg-Lys-Tyr-Cys-Pro-Lys-Val-Gly-Tyr-Cys-Ser-Ser-Lys-Cys-Ser-Lys-Ala-Asp-Val-Trp-Ser-Leu-Ser-Ser-Asp-Cys-Lys-Phe-Tyr-Cys-Cys-Leu-Pro-Pro-Gly-Trp-Lys. There is significant homology between this protein, provisionally designated cygnin, and the NH2-terminal region of the second domain of chicken ovotransferrin. The disulfide bonds have not been assigned; however, the arrangement of half-cystines in cygnin is sufficiently different from that of the known transferrins to suggest that cygnin is derived from another gene.

Amino Acid Sequence↗
PubMed1983

General practitioners' satisfaction with a primary care clinical psychology service.

A specialist Clinical Psychology Service in Primary Care was set up in one health district in 1979 on a three-year experimental basis. A survey conducted among the general practitioners who had used the service during this period found a high level of satisfaction. The views of the general practitioners are reported and also their ratings of the outcome of psychological treatment in each of 305 cases. The relationship between certain patient characteristics and treatment outcome is also presented. These results are discussed in relation to further research required in this area and the future of liaison between clinical psychologists and general practitioners.

Adult↗
PubMed1982

A 1H n.m.r. study of the kinetic properties expressed by glyceraldehyde phosphate dehydrogenase in the intact human erythrocyte.

Glyceraldehyde phosphate dehydrogenase is one of four glycolytic enzymes in the human erythrocyte that together can catalyse exchange of isotope between the C-2 position of lactate and solvent. Detailed measurements of the exchange can be made by using a non-invasive spin-echo p.m.r. method that has been described previously [Brindle, Brown, Campbell, Foxall & Simpson (1982) Biochem. J. 202, 589-602]. By studying the dependence of the exchange on the activity of an individual enzyme, the specific isotope-exchange equilibrium velocity of the enzyme can be measured. Suggestions that glyceraldehyde phosphate dehydrogenase is bound to the membrane in the intact cell, and that it may, under certain conditions, be rate-limiting for glycolytic flux, were examined in the present study by comparing the exchange properties expressed by the enzyme in situ and in vitro. It is concluded that glyceraldehyde phosphate dehydrogenase is not rate-limiting for glycolytic flux and that it is unlikely that a significant fraction of the enzyme is bound to the erythrocyte membrane in situ.

Erythrocyte Membrane↗
PubMed1982

Spin ECHO proton NMR studies of the metabolism of malate and fumarate in human erythrocytes. Dependence on free NAD levels.

The NAD-dependent conversion of malate to lactate in human erythrocytes was studied by spin echo proton NMR. A pathway involving the decarboxylation of oxaloacetate catalysed by haemoglobin is proposed to account for the observed reaction. NADP-dependent reaction was negligible. The rate of the reaction was measured in intact erythrocytes under controlled conditions. This rate correlates with that obtained with lysates at 30 microM free NAD and that obtained with purified human erythrocyte enzymes at about 15 microM NAD. The total extractable NAD in the intact cells was 70-90 microM. Experiments with cells containing elevated NAD levels could be explained by a significant fraction of the NAD being weakly bound (Kd about 1 mM) to haemoglobin.

Biological Transport↗
PubMed1982

A p.m.r. isotope-exchange method for studying the kinetic properties of dehydrogenases in intact cells.

A method to determine the activity of dehydrogenases in an intact-cell system is described. The method involves the use of n.m.r. to monitor bulk isotope exchange. The approach is illustrated by application to the isotope equilibration of pyruvate and lactate as catalyzed by lactate dehydrogenase in intact erythrocytes. Particular problems peculiar to bulk isotope exchange and its observation by n.m.r. are considered.

Erythrocytes↗
PubMed1982

Studies of lactate dehydrogenase in the purified state and in intact erythrocytes.

Lactate dehydrogenase in intact erythrocytes was studied by observing isotope exchange between lactate and pyruvate by p.m.r. The inhibition of the enzyme in intact cells by both oxalate and pyruvate was found to be similar to that of the purified enzyme. The activity of the enzyme in intact cells indicates that the free solution NAD+ + NADH concentration in erythrocytes is about 10 microM whereas the total extractable NAD+ + NADH is about 80 nmol/ml of cell water.

Erythrocytes↗
PubMed1982

A 1H n.m.r. study of isotope exchange catalysed by glycolytic enzymes in the human erythrocyte.

The exchange of hydrogen and deuterium atoms between the C-2 position of lactate and solvent was monitored in suspensions of human erythrocytes by using a non-invasive spin-echo p.m.r. method that permits continuous assessment of the rate and the extent of exchange. Exchange rates were measured in cells suspended in buffers made in 2H2O and 1H2O after the addition of L-[2-1H]lactate and L-[2-2H]lactate respectively. The rate of exchange is dependent on the activities of four glycolytic enzymes (fructose bisphosphate aldolase, triose phosphate isomerase, glyceraldehyde phosphate dehydrogenase and lactate dehydrogenase) and on the concentrations of their substrates. The dependence of the exchange on the following substrates was studied: (1) lactate, (2) the triose phosphates and fructose 1,6-bisphosphate and (3) pyruvate. Observation of the exchange in vitro, in a system produced by mixing the isolated enzymes, permits determination of the individual isotope-exchange equilibrium velocities of the enzymes. The dependence of the equilibrium velocity of human erythrocyte lactate dehydrogenase on NAD+ + NADH concentration was measured. Possible applications of these methods are discussed.

Carbohydrate Epimerases↗
PubMed1982

Atrial excitability and conduction in patients with interatrial conduction defects.

Prolongation of P-wave duration is an accepted indicator of an interatrial conduction disturbance and may predispose patients to atrial arrhythmias. This study was performed to monitor electrophysiologic characteristics of the atria in patients with a prolonged P-wave duration. Atrial excitability and conduction times were compared in 7 patients with a P-wave duration of less than 115 ms (Group I), and 13 patients with a duration of greater than of equal to 115 ms (Group II). In contrast of the Group I patients, most of the 13 patients in Group II had atrial arrhythmias, including sinus nodal dysfunction (3 patients) and a history of atrial fibrillation or ectopic atrial tachycardia (6 patients). Electrophysiologic differences between the 2 groups included a higher late diastolic threshold in Group II (0.8 +/- 0.2 mA versus 1.3 +/- 0.2 mA; p less than 0.005), and a greater increase in intraatrial conduction time (5 +/- 10 ms versus 30 +/- 20 ms; p less than 0.005) and interatrial conduction time (5 +/- 15 ms versus 30 +/- 15 ms; p less than 0.05) of early premature responses. There were no differences between the 2 groups in refractory periods, shape of the strength interval curve, or conduction times of premature responses occurring late in diastole. These abnormalities in conduction time and excitability found in patients with a prolonged P-wave duration may predispose to the initiation of certain atrial tachyarrhythmias.

Adult↗
PubMed1982

Amino acid sequence of a basic blue protein from cucumber seedlings.

The amino acid sequence of a type 1 copper protein, the 96-residue basic blue protein from cucumber seedlings, has been determined by Edman degradation of the intact molecule and of fragments produced by cleavage with cyanogen bromide and with trypsin. The cucumber basic blue protein shows a marked sequence homology with stellacyanin, and to a smaller degree with plastocyanin and azurin. The known copper ligands of plastocyanin and azurin (corresponding to histidine-37, cysteine-84, histidine-87, and methionine-92 in plastocyanin) are present in the cucumber basic blue protein. However, the latter also contains a half-cystine residue analogous to the suggested fourth ligand of stellacyanin, where methionine is absent.

Journal Article↗
PubMed1981

Studies of pyruvate-water isotope exchange catalysed by erythrocytes and proteins.

Erythrocyte suspensions in buffer made with 2H2O catalyse the exchange of pyruvate protons. This process can be easly observed by spin-echo proton magnetic resonance. The dominant exchange process is shown to be due to the formation of Schiff-base links between pyruvate and amino groups of haemoglobin. Other proteins with free alpha-amino groups also catalyse the exchange. The pH*-dependence of the exchange rate due to hen-egg-white-lysozyme reflects the dissociation of the alpha-amino group.

Amino Acids↗
PubMed1980

Event recording in a clinical trial of a new medicine.

In a double-blind trial of the effect of zimelidine on weight and appetite 24 obese patients were allocated at random to receive either zimelidine or placebo for eight weeks followed by the alternative treatment for eight weeks. Possible adverse effects were elicited by asking patients at weekly intervals whether they had experienced any symptoms or ailments and recording all such "events" on a special form. A conventional checklist of symptoms was also used. Among 19 patients who completed the trial the two methods of recording yielded similar patterns of events. Of symptoms not on the checklist, insomnia was more common during treatment with zimelidine. Event recording was found to be a practicable and convenient method of detecting possible adverse effects.

Adult↗
PubMed1979

Blood-pressure screening and supervision in general practice.

Since April 1975 all men aged 35-69 years registered with four general practices in west central Scotland have had their blood pressure checked whenever they visit the surgery. Although the practice locations range from rural to city centre and observers comprise receptionists, nurses, and doctors, a standard procedure has been adopted for the examination, recording, follow-up, and management of high blood pressure. The results confirm that raised blood pressure is common and often goes undetected. Even when hypertension is known, casual blood pressure readings often exceed accepted normal levels. The findings also show that a population may be routinely examined through normal contact with the family doctor, and that this can provide a convenient, acceptable, and effective means of detecting and reducing raised blood pressure.

Adult↗