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Biomedical subjects

M Boulton

Publications and source records attributed to M Boulton.

118 records · Page 7Linked to original sources
PubMed1986

Effects of increasing numbers of phagocytic inclusions on human retinal pigment epithelial cells in culture: a model for aging.

Cultures of human retinal pigment epithelial cells have been challenged with a number of biological (lipofuscin, melanin, and rod outer segments) and non-biological (latex microspheres) particles at a variety of concentrations. The particles were chosen to include examples of both degradable and non-degradable systems. A range of morphological changes were observed by phase contrast microscopy, and these became more atypical with increasing concentration. At the highest concentration cells had ingested so many particles that many had died and others had ruptured. The time course of these changes indicated a relationship between cellular lytic activity and the capacity of the particle to degrade. The potential of this system as a model for studying senescence is discussed.

Aging↗
PubMed1986

Investigations of cytoskeletal elements in cultured bovine meshwork cells.

An ultrastructural, immunohistochemical, and functional study was conducted on cultured bovine meshwork cells. Particular emphasis was placed on the organization of the cytoskeleton, and the cells were viewed either as whole cells or following detergent extraction. For ultrastructural examination, several modes of viewing were adopted, including a detector situated above the specimens collecting secondary electrons (SE), a detector situated beneath the specimen collecting transmitted electrons (STEM), and conventional transmission electron microscopy at 100 KV (TEM). In whole cell mounts, information was obtained about the organization of the cytoskeleton and its relationship to other cytoplasmic organelles. Extraction procedures removed much of the plasma membrane and most organelles. The nucleus and cytoskeleton remained and stress fibers were prominent. Immunohistochemistry showed that the actin content of the cytoskeleton could be preserved after detergent extraction. Detergent-extracted cells decreased their surface area when exposed to MgATP in a dose-dependent manner. The decrease in surface area was associated with disassembly of cytoskeletal stress fibers and was optimal with 1 mM MgATP. Whether or not the change in surface area could be considered a "contractile event" was discussed.

Actins↗
PubMed1985

Repigmentation of human retinal pigment epithelial cells in vitro.

Cultured human retinal pigment epithelial (RPE) cells readily ingested both melanin and lipofuscin isolated from human RPE cells. Up to 7 days post-challenge ingested granules demonstrated no evidence of lysis or aggregation within secondary lysosomes. When cultures containing ingested melanin and lipofuscin were subcultured the cells gradually depigmented due to a redistribution of pigment granules amongst daughter cells. Quantitative analysis demonstrated that the accumulation of both types of granule was linear over a 24 hr challenge period. This study reports a technique of 'artificially' repigmenting cultured human RPE cells and thus offers the potential for in vitro investigations of the role of these inclusions in various dynamic aspects of cellular metabolism.

Adult↗
PubMed1984

Retinitis pigmentosa: a quantitative study of the apical membrane of normal and dystrophic human retinal pigment epithelial cells in tissue culture in relation to phagocytosis.

The phagocytic capabilities of both normal and dystrophic human retinal pigment epithelial cells were assessed by challenging cultures with both non-biological and biological particles. Cells from either source ingested both carbon particles and latex microspheres. Quantification of the phagocytic process in relation to microspheres showed that uptake was linear over an 8 h period and the rate was dose-dependent. All cultures phagocytosed rod outer segments from a variety of species, but excluded bacteria. By using bovine rod outer segments labelled with [H3] choline both normal and dystrophic cells were still accumulating label 24 h subsequent to challenge; however, this technique had significant problems. The introduction of any particulate matter into the culture medium resulted in changes in the apical membrane of the recipient cells. Such responses were quantified in terms of apical projections per unit area. Counts were always greater in cells challenged with biological material even if the material was not engulfed.

Aged↗
PubMed1984

Improving communication: a practical programme for teaching trainees about communication issues in the general practice consultation.

This paper describes a teaching programme, for use in general practice vocational training, which provides a theoretical and practical framework for exploring key aspects of the consultation with trainees. A particular emphasis is on the educational or 'cognitive' outcomes of the consultation and skills for improving them. The five stages of the programme are described and an example of experience of each stage is given. The paper concludes with an evaluation of the programme by the trainers, trainees and social scientist involved.

Communication↗
PubMedDate not supplied

'Dividing the desolation': clients views on the benefits of a cancer counselling service.

This paper describes clients' accounts of the benefits they derived from a short course of cancer counselling provided within a humanist framework. Three hundred and two clients who had attended at least one session of a short course of cancer counselling received an evaluation form, which incorporated both fixed-choice and open-ended questions. One hundred and forty two (47%) clients returned evaluation forms; those who had attended more sessions were significantly more likely to do so. Quantitative data were analysed using SPSS (Statistical Package for the Social Sciences) for Windows and qualitative data using a thematic approach. Almost all clients indicated that they felt they had benefited from counselling. Analysis of the open-ended questions identified nine main benefits of counselling and four key avenues or processes through which clients derived these benefits. Overall, counselling was seen as helping them to work through powerful thoughts and feelings and so to come to terms with cancer and to regain a sense of control in their lives. The benefits of a short course of counselling which clients identified reflect the aims of humanistic counselling which are not well captured by psychiatric assessments or most standard research instruments. In evaluating cancer counselling services, assessments which include these client-defined outcomes may provide a more sensitive way of gauging the value of counselling to a non-clinic population.

Adult↗
PubMedDate not supplied

The role of oxidative stress in the pathogenesis of age-related macular degeneration.

Age-related macular degeneration (AMD) is the leading cause of blind registration in the developed world, and yet its pathogenesis remains poorly understood. Oxidative stress, which refers to cellular damage caused by reactive oxygen intermediates (ROI), has been implicated in many disease processes, especially age-related disorders. ROIs include free radicals, hydrogen peroxide, and singlet oxygen, and they are often the byproducts of oxygen metabolism. The retina is particularly susceptible to oxidative stress because of its high consumption of oxygen, its high proportion of polyunsaturated fatty acids, and its exposure to visible light. In vitro studies have consistently shown that photochemical retinal injury is attributable to oxidative stress and that the antioxidant vitamins A, C, and E protect against this type of injury. Furthermore, there is strong evidence suggesting that lipofuscin is derived, at least in part, from oxidatively damaged photoreceptor outer segments and that it is itself a photoreactive substance. However, the relationships between dietary and serum levels of the antioxidant vitamins and age-related macular disease are less clear, although a protective effect of high plasma concentrations of alpha-tocopherol has been convincingly demonstrated. Macular pigment is also believed to limit retinal oxidative damage by absorbing incoming blue light and/or quenching ROIs. Many putative risk-factors for AMD have been linked to a lack of macular pigment, including female gender, lens density, tobacco use, light iris color, and reduced visual sensitivity. Moreover, the Eye Disease Case-Control Study found that high plasma levels of lutein and zeaxanthin were associated with reduced risk of neovascular AMD. The concept that AMD can be attributed to cumulative oxidative stress is enticing, but remains unproven. With a view to reducing oxidative damage, the effect of nutritional antioxidant supplements on the onset and natural course of age-related macular disease is currently being evaluated.

Aging↗
PubMedDate not supplied

Protein kinase C isoenzyme expression in retinal cells.

Protein kinase C (PKC) is involved in both the physiological and pathophysiological processes in the retina and plays an important role in signal transduction. The aim of this study was to determine the PKC isoenzyme profile in three retinal cell types in culture, namely RPE cells, pericytes and retinal microvascular endothelial cells. Confluent cultures were lysed and isoenzyme expression detected by Western blotting. PKC isoenzymes alpha, beta(2) and delta were observed for all three cell types while beta(1) was specific for RPE cells. This study has characterised the PKC isoenzyme profile in three retinal cell types and suggests that defining the cell-specific isoenzyme pattern is an important step in understanding their precise physiological role and regulation in the retina.

Animals↗