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Biomedical subjects

A M Wilson

Publications and source records attributed to A M Wilson.

At least 19 recordsLinked to original sources
PubMed1992

Functional significance of the morphology and micromechanics of collagen fibres in relation to partial rupture of the superficial digital flexor tendon in racehorses.

The high incidence of partial rupture of the superficial digital flexor tendor in the equine athlete represents a major cause for concern in the racing industry. Frequently, the lesion is localised to the central core of the tendon. This study tested the hypothesis that the site specific structural failure results from differences in the collagen fibre morphology and associated micromechanics between central and peripheral regions of the tendon. Bundles of collagen fibres were dissected from central and peripheral sites in the mid-metacarpal region of the tendon. Crimp morphology was quantified by polarised light microscopy and mechanical characteristics determined using a fibre tensometer. In older horses, centrally located fibres showed significantly lower values for crimp angle, crimp length and toe limit strain than seen peripherally. There were no significant differences in these features between corresponding sites in the younger horses. No significant difference between sites was found in elastic modulus in either group. These data indicate a non-uniform functional stress distribution which may result from ageing or be related to the exercise history as a feature of accumulated damage. These observations may explain the location of central core lesions seen on clinical examination.

Aging↗
PubMed1991

Turtle cortical neurons survive glutamate exposures that are lethal to mammalian neurons.

Glutamate is an excitatory neurotransmitter in turtle and mammalian cortex. In high concentrations it is toxic to mammalian neurons and is an important mediator in the pathway that leads to neuronal death from anoxia. Turtle neurons are remarkably resistant to anoxic injury and we sought to determine whether part of this resistance could be attributed to the sensitivity of turtle neurons to glutamate toxicity. Embryonic turtle cortical neurons were grown for 25 days in dissociated cell culture using a modification of a method developed for murine cortical cell culture. Turtle neurons in dissociated culture were found to express glutamate receptors which include both N-methyl-D-aspartate (NMDA) and non-NMDA receptor types. Remarkably, these neurons survive 5 minute exposures to glutamate in concentrations up to 3 mM, doses 30 times the LD50 and 6 times the LD100 for mouse cortical neurons. Elucidating the mechanism for this resistance may suggest new strategies for brain protection.

Animals↗
PubMed1990

A comparison of anorexia nervosa and affective psychosis in young females.

In a retrospective case note study, 73 young females with anorexia nervosa were compared with 88 young females with affective psychosis. These groups of patients did not differ in terms of place of residence, birth order or social class. They differed very significantly, however, in terms of age at onset of symptoms, marital status, educational attainments and in the pattern of family histories of psychiatric illness. It is concluded that anorexics and young females with affective disorders are two quite distinct groups of patients.

Adolescent↗
PubMed1990

Description of two new nomogram/calculators for categorising oxygenation status.

Presentation of blood gas results requires knowledge of the position of the oxygen dissociation curve (ODC) to give a complete indication of oxygenation status. Many computations rely on the shift of the ODC occurring with a constant proportional value throughout its length, with no change of shape. If this consistency is accepted it permits geometric manipulation of the curve and the construction of accurate hand held mechanical calculators. Two examples of such calculators are presented. From the measured values of oxygen partial pressure, saturation and haemoglobin concentration they will present many of the new proposed units.

Blood Gas Analysis↗
PubMed1989

Application of airline pilots' hours to junior doctors.

OBJECTIVE: To determine the staff required if the rules for airline pilots' hours of work are applied to junior doctors. DESIGN: Junior anaesthetists recorded their workload from 1 March 1988 to May 31 1988. SETTING: District general hospital. SUBJECTS: Two groups of three junior anaesthetists sharing a one in three rota to provide continuous emergency cover. INTERVENTIONS: By using the guidelines published by the Civil Aviation Authority in The Avoidance of Excessive Fatigue in Aircrews schedules were drawn up to cover the hours that junior doctors had been on duty. RESULTS: Each anaesthetist provided emergency and routine cover for 48-112 (mean 75) hours each week. To cover the work of six junior anaesthetists on an annual basis would require 26 doctors if they were working within the Civil Aviation Authority's guidelines. CONCLUSIONS: Junior anaesthetists' hours are much longer than those of airline pilots. Both professions entail considerable periods of monitoring interspersed with episodes of high demands on physical and cognitive skills. Errors induced by fatigue made by anaesthetists and pilots could result in death. The medical profession should define rules similar to those of the aviation authority to prevent junior doctors having to work unsafe numbers of hours.

Anesthesiology↗
PubMed1986

Combination chemoprevention of rat mammary carcinogenesis by indomethacin and butylated hydroxytoluene.

Indomethacin, a nonsteroidal antiinflammatory agent which inhibits prostaglandin biosynthesis, is an effective inhibitor of mammary carcinogenesis in rats. However, the activity of indomethacin as a chemopreventive agent is limited by toxicity. The present studies were conducted to determine if the toxic and anticarcinogenic effects of indomethacin can be modified by the phenolic antioxidant, butylated hydroxytoluene (BHT). Simultaneous administration of BHT resulted in a dose-related inhibition of indomethacin toxicity in female Sprague-Dawley rats, and increased the tolerable indomethacin dose from 50 to 150 mg/kg diet. When BHT (5000 mg/kg diet) and indomethacin (50 mg/kg diet) were administered in combination, no increased inhibition of 7,12-dimethylbenz(a)anthracene-induced mammary carcinogenesis was observed above that attained by administration of BHT alone or indomethacin alone at those doses. However, when the indomethacin dose was increased to 100 mg/kg diet, an enhanced inhibition of carcinogenesis was attained when BHT and indomethacin were administered from 2 weeks prior to until 1 week after 7,12-dimethylbenz(a)anthracene administration. These data indicate that "combination chemoprevention" regimens can be utilized to reduce the toxicity of anticarcinogenic drugs. However, the BHT-indomethacin interaction appears to involve a functional or dispositional antagonism which limits the anticarcinogenic efficacy of increasing indomethacin dose level.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1984

Localisation of enteropathogens in paraffin embedded tissue by immunoperoxidase.

An indirect immunoperoxidase technique has been used to identify enteropathogens in formol-sublimate fixed paraffin embedded sections of calf intestine. Infections with bovine rotavirus, bovine coronavirus, Newbury agent SRV -1, and K99+ Escherichia coli have been detected in the intestines from experimentally infected and conventially reared diarrhoeic or normal calves. The ability to visualize enteropathogenic agents in histological sections resulted in the demonstration of virus infected cells at sites not previously shown to be infected using the immunofluorescence technique.

Animals↗
PubMed1983

Vibrotactile identification of vowels.

The ability of subjects to identify vowels in vibrotactile transformations of consonant-vowel syllables was measured for two types of displays: a spectral display (frequency by intensity), and a vocal tract area function display (vocal tract location by cross-sectional area). Both displays were presented to the fingertip via the tactile display of the Optacon transducer. In the first experiments the spectral display was effective for identifying vowels in /b/V/ context when as many as 24 or as few as eight spectral channels were presented to the skin. However, performance fell when the 12- and 8-channel displays were reduced in size to occupy 1/2 or 1/3 of the 24-row tactile matrix. The effect of reducing the size of the display was greater when the spectrum was represented as a solid histogram ("filled" patterns) than when it was represented as a simple spectral contour ("unfilled" patterns). Spatial masking within the filled pattern was postulated as the cause for this decline in performance. Another experiment measured the utility of the spectral display when the syllables were produced by multiple speakers. The resulting increase in response confusions was primarily attributable to variations in the tactile patterns caused by differences in vocal tract resonances among the speakers. The final experiment found an area function display to be inferior to the spectral display for identification of vowels. The results demonstrate that a two-dimensional spectral display is worthy of further development as a basic vibrotactile display for speech.

Communication Devices for People with Disabilities↗