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Biomedical subjects

A Murray

Publications and source records attributed to A Murray.

At least 379 records · Page 21Linked to original sources
PubMed1980

The salutary effect of milk on amoebiasis and its reversal by iron.

Observations among milk-drinking African nomads showed an unusual freedom from infection with Entamoeba histolytica compared with similar nomads taking a mixed diet. A controlled study among Maasai pastoralists showed that the administration of iron to correct their dietary iron deficiency sharply increased their susceptibility to amoebiasis. Examination of the milk of their Zebu cattle showed that it not only had a concentration of iron below the minimum necessary for the growth of E histolytica but also contained partly saturated lactoferrin and transferrin, which may actively compete with the parasite in the colon for ambient iron. These observations suggest the possibility of a long-standing ecological compromise between nomads, their milk diet, and E histolytica.

Adult↗
PubMed1980

Autonomic mechanisms in the initial heart rate response to standing.

Autonomic mechanisms underlying the initial heart rate response to standing were analyzed in nine normal subjects. The normal pattern of response was altered by atropine to a small and gradual R-R interval shortening over 30 beats, with no rebound R-R interval lengthening. With additional propranolol, R-R interval shortening was even less and confined to the first 15-20 beats, whereas propranolol alone did not affect the normal response pattern, showing that this is under vagal control with increased cardiac sympathetic activity occurring only if the vagus is blocked. The response was reproducible in 23 normal subjects. Heart rate variation during quiet standing was almost completely abolished by atropine, but unaffected by propranolol, confirming that it is also under vagal control. In four normal subjects no rebound R-R interval lengthening occurred during either "fast" or "slow" tilt, whereas it was present during both "slow" and "fast" standing. The rebound R-R interval lengthening is determined by the muscular activity involved in standing up, rather than by the speed of the maneuver.

Adult↗
PubMed1979

Head injuries in three Scottish neurosurgical units. Scottish head injury management study.

The organisation of care for patients with head injuries in Scotland was investigated by studying retrospectively 785 patients admitted in 1974 and 1975 to neurosurgical units in Glasgow, Aberdeen, and Dundee. The reasons for the injuries and the patients' clinical conditions were similar in each unit. The referral practices at the hospitals containing the units were compared and found to be different from that of the unit in Edinburgh. It is concluded that patients in the Glasgow, Aberdeen, and Dundee units, which operate a similar policy for head-injured patients, are in general similar. Transferring to a neurosurgical unit only selected patients rather than all patients with head injuries is safe practice only if policies are agreed with primary surgeons and patients can be transferred without delay.

Adolescent↗
PubMed1979

Coupling interval, exit block, and periodicity of ventricular parasystolic rhythm.

The electrocardiograms in this study of parasystolic rhythm were tape recorded and then analysed with a special purpose hybrid computer. The rate of appearance of specific inter-ectopic intervals was shown to change significantly with small changes in either the sinus or parasystolic pacemaker period. Natural changes in the period of the ectopic pacemakers were observed over several hours. Changes amounting to 14% within 10 min and 18% overall were observed in one patient, and a gradual lengthening of 10% over 3 h in another. A previously undescribed form of exit block has been discovered in one patient where the block remained active for a given time only after propagation from the parasystolic focus. Different interectopic intervals were shown to contribute to specific and restricted coupling interval locations in diastole. Hence this form of exit block, by preventing some inter-ectopic intervals from propagating, limited the locations in diastole in which parasystolic ectopic complexes could appear. In this case later diastolic complexes were inhibited and hence fusion complexes were completely absent. Parasystolic rhythm, with and without the exit block described, was simulated successfully by a digital computer. The simulations aided our understanding of the clinical data.

Aged↗
PubMed1979

Interdose control of beta-blockade and arterial blood pressure during chronic oral labetalol treatment.

1 The pharmacological and therapeutic effects of labetalol were investigated during an 8 h interdose period of chronic oral therapy in six patients with essential hypertension. 2 Peak plasma labetalol concentrations were observed 2 h after the morning oral dose, and subsequent decline was mono exponential. 3 Beta-adrenoceptor blockade paralleled the changes in labetalol concentration and was maximal 2 and 4 h after the oral dose. 4 Resting supine systolic BP rose significantly during the interdose period, but no change occurred in diastolic BP. 5 Ambulatory intra-arterial BP studies in a further six patients with essential hypertension controlled with labetalol did not confirm the increase in BP during an 8 h interdose period.

Adrenergic beta-Antagonists↗
PubMed1978

Immediate heart-rate response to standing: simple test for autonomic neuropathy in diabetes.

The immediate heart-rate response to standing was measured in 22 normal controls and 25 patients with diabetes, 15 of whom had autonomic neuropathy. The response in the controls and patients without autonomic neuropathy was characteristic and consistent, with tachycardia maximal at around the 15th beat and relative bradycardia maximal at around the 30th beat. The diabetics with autonomic neuropathy, however, showed a flat response. In three controls the response was abolished with intravenous atropine but not with propranolol, showing that it is mediated through the vagus. A simplified test using routine ECGs and measuring the R-R interval at beats 15 and 30 with a ruler is easily performed as an outpatient procedure and may be used as a measure of autonomic function in diabetes.

Adult↗
PubMed1978

Studies on intercellular LETS glycoprotein matrices.

Intercellular matrices secreted by chick embryo fibroblasts in culture were studied by scanning electron microscopy. Cell-cell contact is a prerequisite for the expression of such matrices. The smallest fiber detected by transmission electron microscopy is 5--10 nm in diameter. These matrix fibers tend to cluster to form bundles. Immunofluorescence and immunoferritin procedures reveal that LETS protein is one of the components of the matrices. The matrices are isolated from other cellular organelles by detergent treatment. More than 90% of the proteins in cell-free matrices are LETS protein, suggesting that the matrices are probably made of only one component--LETS protein. Since the solubilization of matrices requires beta-mercaptoethanol, LETS protein matrices may be the first known polymer system in nature to use disulfide linkage as an intermolecular polymerization vehicle. Collagen does not appear to be involved in such matrices. The LETS protein matrix supports the morphological conversion of rounded cells into spindle-shaped, and also promotes myoblast fusion. It does not, however, exert an effect upon cell growth, the rate of glucose uptake or protease production.

Cell Count↗
PubMed1978

The biological suppression of malaria: an ecological and nutritional interrelationship of a host and two parasites.

The interrelationship of malaria and severe ascariasis was studied in Anjouan children with a previously described syndrome of enlarged parotids, localized forehead edema, heavy infestation with Ascaris lumbricoides, and unusual freedom from malaria. After treatment of 37 such children with the ascaricide piperazine, 35 had resolution of parotid enlargement and forehead edema, but 19 developed attacks of malaria. Children treated with placebo had neither resolution of clinical findings nor attacks of malaria. We propose that suppression of the malaria in these children is a nutritional consequence of severe ascariasis and may represent an ecological balance for optimum co-survival of the host and the two parasites.

Adolescent↗
PubMed1977

Praecordial ST segment elevation. New technique for continuous recording and analysis.

The measurement of praecordial ST segment elevation after myocardial infarction is of value in assessing the natural history of ischaemic injury and the effectiveness of intervention. Hand analysis is, however, time consuming and inaccurate. A technique for continuous recording from 35 praecordial leads and subsequent computer analysis is presented, together with illustrative case studies. Changes in body posture and in heart rate are of importance in subsequent data interpretation.

Adult↗