Biomedical subjects
F Harrison
Publications and source records attributed to F Harrison.
Interplay between adrenaline and interbeat interval on ventricular repolarisation in intact heart in vivo.
STUDY OBJECTIVE: The aim was to examine the hypothesis that an interaction between adrenaline and change in heart rate may alter the normal time sequence of ventricular repolarisation (and hence refractoriness) in a manner that (1) may favour arrhythmia formation, (2) may partly explain conflicting reports of the effect of adrenaline, ie, there are two opposing effects on action potential duration, and (3) be relevant to T wave abnormalities that sometimes occur in normal people. DESIGN: As a measure of the time course of repolarisation, monophasic action potentials were recorded simultaneously from three epicardial sites in the porcine heart (left ventricular apex, left ventricular base, and mid right ventricle). During steady state pacing, test pulse intervals were interposed at progressively shorter intervals in order to construct restitution curves. MEASUREMENTS AND MAIN RESULTS: Adrenaline infusion (0.4-1.5 micrograms.kg-1.min-1) resulted in earlier repolarisation in the beats after shorter interbeat intervals, and delayed repolarisation after longer interbeat intervals, tending to turn the restitution curve anticlockwise (ie, there were two opposing effects on action potential duration). The effects were not homogeneous between regions. To show this inhomogeneity, pairs of monophasic action potentials from different regions were subtracted using a differential input amplifier to produce an ECG like waveform at the amplifier output. The resulting T wave was thereby a measure of the time difference in repolarisation between the monophasic action potentials from which it was derived. The inhomogeneity of repolarisation induced by adrenaline and rate change was reflected in the morphology of this derived T wave, particularly at early (premature) beats. These T wave changes correlated closely with the true T wave changes in bipolar electrograms recorded between the same recording sites (R = 0.89; p less than 0.0001). CONCLUSIONS: These results show that adrenaline altered the normal relationship between interbeat interval and the timing of repolarisation. The effect was not homogeneous and when regional differences were observed they were reflected in changes in T wave morphology. These were marked at short intervals. It is possible that in addition to increased excitability observed with adrenaline, a combination of raised sympathetic activity and early beats predisposes to arrhythmias by exaggerating dispersion of repolarisation.
High tech in the hospital--impact on the nurse administrator.
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Time to look again at role-based training for nurse managers.
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Zinc, copper, iron and lead in scalp hair of students and non-student adults in Oxford.
Scalp hair samples contributed by 215 students and non-student adults in Oxford were washed, ashed and analysed by atomic absorption spectrophotometry for zinc, iron, copper and lead. The overall results were within the ranges reported from similar investigations carried out elsewhere and are what might be expected with normal, healthy subjects. However, examination of the results for different groups showed some significant differences between levels of the nutrient metals in student and non-student hair. Results for lead indicate a low level of environmental contamination for all subjects.
Patient classification by types of care.
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A contemporary dilemma in nursing administration.
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Viscerosomatic interactions in lumbar spinal cord of the cat.
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