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Biomedical subjects

D Sutton

Publications and source records attributed to D Sutton.

At least 55 records · Page 3Linked to original sources
PubMed1985

Profile analysis in facial plastic surgery.

We devised a simple and reliable method of profile analysis for facial plastic surgery. Profile photographs are taken with the natural head position technique. Key cephalometric landmarks are then identified and digitalized from either photographs or slides, using a digitalizer with a resolution of 0.001 in. The digitalizing pad is connected to a microcomputer. The menu-driven software allows selection of multiple functions from different cephalometric systems. Data can be stored on disk for future analysis. The method is useful in preoperative planning and postoperative evaluation of facial plastic surgery procedures.

Face↗
PubMed1985

Discriminative phonation in macaques: effects of anterior mesial cortex damage.

Lesion damage of the anterior midline hemisphere in M. mulatta results in impaired discriminative vocal activity. Destruction of the supplementary motor area (SMA) or pre-SMA greatly increases vocal response latency without similar changes in a non-vocal response. Discrimination and efficiency in performing the vocal and non-vocal responses are unaffected by this damage. The behavioral deficit reflects a specific loss in initiating vocal signals.

Animals↗
PubMed1985

Computed tomography in deep-seated peripheral neurofibromas.

Seven peripheral deep-seated neurofibromas in five patients were examined by computed tomography (CT). This proved to be the most helpful investigation for demonstrating the precise size, shape and localisation of the lesion prior to surgery. In some cases CT may suggest the correct diagnosis where this has not previously been considered.

Adult↗
PubMed1984

Cochlear pathology. Hazards of long-term implants.

There is increasingly diverse evidence that multichannel intrascalar or modiolar implants can cause long-term changes in cochlear structure. Experimental studies show that nerve-cell loss and osteogenesis are related to electrical stimulation. Low charge densities may limit such intracochlear changes. Middle-ear stimulation presents an alternative to the intracochlear implant, although its degree of effectiveness is not well characterized. Monitoring electrically produced auditory brain-stem responses may help detect progressive pathologic changes occurring in the implanted cochlea.

Acoustic Stimulation↗
PubMed1983

Spontaneous aorto-caval fistulae.

The clinical and radiological presentation of four cases of spontaneous aorto-caval fistula is described. This is an unusual complication of an abdominal aortic aneurysm and presents with abdominal pain, a pulsatile abdominal mass and an abdominal bruit. Our cases illustrate the variable clinical presentation, outline the diagnostic difficulties and confirm the value of aortography. A possible role for the radiologist using a balloon catheter to close the fistula prior to surgery is suggested.

Aged↗
PubMed1983

Comparison between 153Gd and 241Am, 137Cs for dual-photon absorptiometry of the spine.

The bone mineral content (BMC) of the spine can be measured from the attenuation of two photon beams. An equation was derived for the theoretical precision of BMC measurement and validated experimentally. Though 153Gd was found to possess the better energy combination, the precision due to the photon energy levels using 241Am, 137Cs was only 1.5 times the value obtained from 153Gd. The available photon outputs from 241Am and 153Gd were investigated and with a 12 mm diameter disc source a theoretical precision of 1% could be obtained with source strengths 20 GBq 241Am or 5GBq 153Gd in a 40 min and 20 min patient scan respectively. There was no great advantage in either energy combination when the problems of fat or patient dose were considered. Given the disadvantages of 153Gd, its cost and availability, 241Am, 137Cs can be used as a practical alternative to measure spine BMC from a reconstructed bone mineral image.

Americium↗
PubMed1983

Advances in the techniques of localisation of adrenal tumours and their influence on the surgical approach to the tumour.

The results of attempts to localise adrenal tumours in 65 patients are presented. In the first series (1966-1978) adrenal phlebography and adrenal vein sampling located 18 of 20 (90%) of adrenocortical tumours and 18 of 19 (94%) phaeochromocytomas were defined by angiography and venous sampling. In the second series CT located 7 of 8 adrenocortical and all 6 intra-abdominal phaeochromocytomas. Scintigraphy located all 9 adrenocortical tumours and both of the phaeochromocytomas examined. Confidence in the ability of newer techniques allows the use of a flank incision in most cases, thus reducing the operative morbidity.

Adrenal Cortex Neoplasms↗
PubMed1983

Intensity discrimination with cochlear implants.

Intensity difference limens were measured for various frequencies and intensities of sinusoidal and pulsatile electrical stimulation in monkeys with electrodes implanted in the scala tympani, scala vestibuli, modiolus, or middle ear. Difference limens decreased, as a function of initial stimulus intensity, from values of 1.5-3 dB near threshold to as low as 0.5 dB near the upper limit of the dynamic range. If sensation level was held constant, difference limens decreased as a function of frequency up to about 500 Hz, and then remained constant. They were similar across a variety of electrode placements and separations if differences in threshold and dynamic range were taken into account. However, difference limens measured in severely damaged ears were slightly smaller than those in moderately damaged ears. The near miss to Weber's law, characteristic of acoustic difference limens, was not seen with electrical stimuli. Differences limens for electrical stimuli were roughly one-half those for acoustic stimuli; thus, part of the deficit in dynamic range for electrical stimulation compared with acoustic stimulation is countered by the smaller intensity differences limens for electrical stimuli.

Acoustic Stimulation↗
PubMed1983

Dual photon absorptiometry of the spine with a low activity source of gadolinium 153.

Apparatus and data-processing techniques were developed to measure the bone mineral content (BMC) of the lumbar spine. 153Gd was used as the dual photon source with an activity down to 7 GBq, lower than that adopted by other workers. The compromise between resolution and sensitivity was optimised. A reproducibility in normal subjects of 1.5% (coefficient of variation) was obtained. Normalisation procedures using parameters of the scan image and other indicators of body size such as span were developed, and reduced the coefficient of variation between normal subjects to 10% for men and 8% for pre-menopausal women. The absolute values of BMC are similar to those reported by others. Cross-sectional studies in women demonstrated an accelerated loss of BMC after the menopause.

Adult↗
PubMed1979

Vestibular effects of electrical stimulation of the cochlea. Monitored in the awake primate.

The effect of electrical stimulation of the cochlea on vestibular response was monitored in six rhesus monkeys. Eye movements and single-unit activity from the vestibular portion of the eighth nerve, vestibular nuclei, reticular formation, and abducens nucleus were observed while electrical stimulation was delivered through an implanted cochlear prosthesis. In one animal of this series, neural activity from the inferior colliculus and cochlear nuclear complex was also recorded. Electrical stimulation elicited eye-movement responses in only one animal. In the animals from which single-unit activity was recorded, no positive vestibular effects were noted. In one animal of this study, responses were elicited from auditory structures by relatively low intensities of electrical stimulation.

Acoustic Stimulation↗
PubMed1978

Cerebellar regulation of phonation in rhesus monkey (Macaca mulatta).

Five rhesus monkeys (Macaca mulatta) were trained to emit a "coo" vocalization with a duration of at least 500 msec. After stable performance was achieved cerebellar lesions were introduced, and various pre- and postlesion measures of phonation and of laryngeal EMG activity were compared to assess the effects of the lesions. The phonatory changes were interpreted with respect to possible laryngeal or respiratory modifications. The relation between fundamental frequency and intensity of phonation was changed in some animals, with no obvious alterations in either fundamental frequency or intensity considered separately. Intensity of phonation was decreased while duration was prolonged in two animals. Fundamental frequency of phonation was also affected in some animals. Reliable laryngeal EMG was obtained in two animals and was affected by cerebellar lesions. These results indicate that normal cerebellar function is involved in the control of fundamental frequency, intensity, duration, and the coordination of the laryngeal and respiratory systems for the control of phonation.

Acoustics↗