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Biomedical subjects

I Burgess

Publications and source records attributed to I Burgess.

At least 19 recordsLinked to original sources
PubMed2005

Influence of the electric field on a bio-mimetic film supported on a gold electrode.

A model biological membrane was formed by fusion of mixed cholesterol and DMPC (dimyristoylphosphatidylcholine) phospholipid vesicles onto a gold-coated quartz support. The gold surface was charged and the influence of the charge at the solid support on the structure and integrity of the phospholipid bilayer was investigated using the specular reflection of neutrons and electrochemical measurements. When the surface charge density is close to zero, the lipid vesicles fuse directly on the surface to form a bilayer with a small number of defects and hence low water content. When the support's surface is negatively charged the film swells and incorporates water due to the field driven poration of the membrane. When the charge density is more negative then -8 microC cm(-2) the bilayer is detached from the metal surface. However, it remains in close proximity to the metal electrode, suspended on a thin cushion of water. The film thicknesses, calculated from neutron reflectivity, have allowed us to determine the tilt angle of the lipid molecules as a function of the support's charge density. The lipid molecules are tilted 55 degrees from the surface normal at zero charge density but become significantly more perpendicular (30 degrees tilt angle) at charge densities more negative than -8 microC cm(-2). The tilt angle measurements are in very good agreement with previous IR studies. This paper describes the highlights of a more in-depth study which is fully described in [1].

Biomimetic Materials↗
PubMed2004

Electric field-driven transformations of a supported model biological membrane--an electrochemical and neutron reflectivity study.

A mixed bilayer of cholesterol and dimyristoylphosphatidylcholine has been formed on a gold-coated block of quartz by fusion of small unilamellar vesicles. The formation of this bilayer lipid membrane on a conductive surface allowed us to study the influence of the support's surface charge on the structure and hydration of the bilayer lipid membrane. We have employed electrochemical measurements and the specular reflection of neutrons to measure the thickness and water content in the bilayer lipid membrane as a function of the charge on the support's surface. When the surface charge density is close to zero, the lipid vesicles fuse directly on the surface to form a bilayer with a small number of defects and hence small water content. When the support's surface is negatively charged the film swells and incorporates water. When the charge density is more negative than -8 micro C cm(-2), the bilayer starts to detach from the metal surface. However, it remains in a close proximity to the metal electrode, being suspended on a thin cushion of the electrolyte. The field-driven transformations of the bilayer lead to significant changes in the film thicknesses. At charge densities more negative than -20 micro C cm(-2), the bilayer is approximately 37 A thick and this number is comparable to the thickness determined for hydrated multilayers of dimyristoylphosphatidylcholine from x-ray diffraction experiments. The thickness of the bilayer decreases at smaller charge densities to become equal to approximately 26 A at zero charge. This result indicates that the tilt of the acyl chains with respect to the bilayer normal changes from approximately 35 degrees to 59 degrees by moving from high negative charges (and potentials) to zero charge on the metal.

Adsorption↗
PubMed1996

SORT: a validation study with stroke patients. Salford Objective Recognition Test.

The Salford Objective Recognition Test (SORT) was developed as a measure of recognition memory suitable for use with elderly people as it requires a shorter administration time than Warrington's Recognition Memory Test. Normative data for the SORT were collected from 50 normal elderly people living in the community. Fifty stroke patients were assessed on the SORT and other tests of psychological functioning. The words and faces subtests were found to correlate well with other measures of memory. The SORT was found to be uninfluenced by the effects of sex and time since onset of stroke, but was affected by language difficulties and perception problems. The split-half reliability of the test was found to be good as alternative versions of the subtests correlated well with each other.

Aged↗
PubMed1995

Coping strategies and phobias: the relationship between fears, phobias and methods of coping with stressors.

Two studies are described which assessed the extent to which fears and phobias are associated with particular types of strategies for coping with stress. Study 1 compared scores on the Fear Survey Schedule (FSS) with scores on a modified version of the Health and Daily Living Form and the Miller Behavioural Style Scale (MBSS) in a normal population. A principal component analysis revealed that high scores on the social fears and miscellaneous phobias subscales of the FSS were directly associated with avoidance coping strategies, inversely associated with cognitive reappraisal strategies which devalue or deny the importance of the stressor, but unrelated to any of the measures on the MBSS. Study 2 compared the coping strategies of simple phobics, panic disorder patients and normal controls. Both simple phobics and panic disorder patients differed from normal control subjects by reporting greater use of avoidance coping strategies, and reduced use of cognitive threat devaluation. These findings are consistent with models of anxiety-based disorders which implicate avoidance or escape in the maintenance of such disorders, or which identify the evaluation of the precipitating trauma as important in the acquisition of such disorders.

Adaptation, Psychological↗
PubMed1994

Disease-avoidance model: factor analysis of common animal fears.

This paper reports the results of two studies investigating a disease-avoidance model of common animal fears. In Study 1, a factor analysis of a variety of self-rated animal fears revealed that these fears can be grouped into two theoretically meaningful categories which correspond to predatory animals and fear-relevant animals. Study 2 found a significant correlation between disgust sensitivity and fear to animals in the fear-relevant category, but not between disgust sensitivity and fear to animals in the predatory category. In addition, fear of animals in the fear-relevant category was significantly associated with scores on the obsessive washing sub-scale of the Maudsley Obsessive-Compulsive Inventory, but was not associated with obsessive behaviour in general.

Adolescent↗
PubMed1990

Chromosome 6q deletions: a report of two additional cases and a review of the literature.

Here we report on two additional cases of distal 6q deletions with one case showing a terminal deletion of chromosome 6 (46,XY, del(6)(pter----q26:)) and one case showing an interstitial deletion of chromosome 6 (46,XY, del(6)(pter----q23::q25----qter)). The association of retinal abnormalities in 6q deletions is supported, and the additional manifestations of skin hyperextensibility, sacral abnormality, and imperforate anus are described.

Abnormalities, Multiple↗
PubMed1985

Bilateral fatigue fractures of the distal fibulae caused by a change of running shoes.

A 26-year-old man sustained bilateral, symmetrical fatigue fractures of his distal fibulae while running in a 14-km road race. He had trained repeatedly over the course without developing any symptoms, but on the day of the race he lost one of his regular running shoes. He competed instead in old, borrowed tennis shoes. After running over a distance of 2 km, he felt pain about 4 cm above the distal end of both fibulae. Two weeks later, radiographs showed bilateral fractures. The change of footwear was the only identifiable factor in the causation of these fractures. Analysis by compression-loading showed that his usual running shoes absorbed twice as much energy and deformed five times as much as those used in the race.

Adult↗