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Biomedical subjects

M Boulton

Publications and source records attributed to M Boulton.

At least 109 records · Page 6Linked to original sources
PubMed1990

Gay men, social support and HIV disease: a study of social integration in the gay community.

As part of a large study of the effects of HIV and AIDS on gay male sexual behaviour, we investigated the extent to which gay men in the UK have access to social support and informal care at times of illness. The study sample (n = 502) demonstrated high levels of willingness to disclose sexuality to others, sociability and social integration. Over 90% reported that they had access to people whom they could turn for practical help at times of temporary incapacity. Between 42% and 46% have known a person, or persons, with HIV symptomatic disease, AIDS or someone who has died of AIDS, although men recruited in larger towns and cities were more likely to know people at every stage of HIV infection and AIDS than those from smaller towns. Twenty-five per cent had provided practical help and support to at least one person with AIDS; men in this situation were more likely to have had a close friend, lover or former lover who had died of AIDS. It is argued that it is not possible to expect the gay community to provide fully for the non-medical care of its members and, whilst some needs can be fulfilled on an informal care basis, the demands of long-term serious illness are such that adequate support services should be available in the community.

Adolescent↗
PubMed1990

Inhibition of microvascular endothelial cell proliferation by vitreous following retinal scatter photocoagulation.

Laser photocoagulation of pig retina induced breakdown of the blood-retinal barrier, with the appearance of serum proteins in the vitreous as determined by sodium dodecyl sulphate/polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting techniques. Vitreous from lasered eyes inhibited the proliferation of cultured retinal microvascular endothelial cells in comparison with vitreous from non-lasered control eyes, and the inhibitory effect in the lasered eyes persisted for at least seven days. Inhibition was specific for endothelial cells, since no effect was observed when retinal pericytes or Tenon's fibroblasts were the target cells. These results suggest that indirect scatter photocoagulation may induce regression of neovascularisation by causing breakdown of the blood-retinal barrier and thus releasing into the vitreous serum components which result in inhibition of retinal microvascular endothelial cell growth.

Animals↗
PubMed1990

Factors influencing condom use in a sample of homosexually active men.

A sample of 502 homosexually active men were recruited from genitourinary medicine clinics and non clinic sources and interviewed in relation to their sexual behaviour and factors that might influence their use of condoms. Three hundred and eighty three men (76%) reported penetrative anal sex in the previous year. Ninety four (25%) had not used condoms in penetrative sex. Failure to use condoms was associated with unfavourable attitudes to them, not knowing close friends or partners who had HIV-related health problems, having fewer sexual partners and being in a closed monogamous relationship. On the other hand levels of awareness about the risks of unprotected anal sex and involvement in gay networks and social groups were not predictors of condom use.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Regional distribution of lysosomal enzymes in the canine retinal pigment epithelium.

We have investigated the activities of four lysosomal enzymes in RPE cells isolated from three regions of the canine fundus: the tapetal area, the central pigmented area and the peripheral area. The results obtained with freshly isolated cells showed that the activities of acid phosphatase, B-glucuronidase and N-acetyl-B-glucosaminidase were significantly higher in RPE cells derived from the peripheral region when compared to those from the two central regions. In contrast, the activity of cathepsin D was significantly higher in the tapetal region than in the periphery. The regional distribution of both acid phosphatase and B-glucuronidase observed in fresh RPE cells was progressively lost when these cells were grown in culture. Estimations of photoreceptor density per RPE cell from each of the regions indicated that the number of photoreceptors per RPE cell did not vary significantly with retinal location and suggested that variations in enzyme content were not related to differences in photoreceptor cell distribution.

Animals↗
PubMed1989

Community attitudes to cystic fibrosis carrier testing in England: a pilot study.

Inexpensive and accurate carrier testing for cystic fibrosis (CF) will be possible in the near future. There are no existing studies on the attitudes of English persons in the community to carrier testing for CF or any other recessive disorder. We have conducted a trial study of 166 persons at two schools, two doctors' surgeries, and a family planning clinic. Only a minority had clear pre-existing knowledge of cystic fibrosis and its genetic nature. However, over 80 per cent of those questioned expressed interest in knowing their carrier status. Although it is well known that uptake can only be assessed when a service is in place, and while further studies are required to confirm that testing will be of interest to couples of reproductive age with no previous knowledge of CF, the data strongly suggest that there will be interest in community-wide testing for CF carrier status when such a test becomes available in the United Kingdom.

Attitude to Health↗
PubMed1989

Growth characteristics of central and peripheral bovine corneal epithelial cells in vitro.

Primary cultures of pure bovine corneal epithelial sheets, isolated from either central or peripheral areas of the cornea and grown on an extracellular matrix, exhibited major differences in relation to their respective growth characteristics and morphology. After 15 days in culture, cells of peripheral origin covered a 40% greater area and were 2.75 times more numerous than those of central origin. Most peripheral cells were small with a polygonal morphology, whereas central cells varied considerably in both size and shape, although areas consisting of large cells were regularly observed. Differences in the rates of proliferation between central and peripheral corneal epithelial cells were maintained throughout the first and second subcultures. However, the growth rates were considerably lower in second passage cultures of both central and peripheral cells when compared with those of first passage. The growth characteristics of primary cultures of pure epithelial sheets were confirmed by further studies on corneal buttons in culture. Our results in vitro strongly support the concept of a slow but steady physiological movement of increasingly differentiated cells from the periphery of the cornea towards the centre, resulting in a constant renewal of epithelial cells in vivo.

Animals↗
PubMed1989

Transplantation of retinal pigment epithelium using a pars plana approach.

We describe a pars plana approach for transplantation of autologous retinal pigment epithelial cells from a peripheral chorioretinal biopsy to prepared Bruch's membrane at the posterior pole of the same eye. The technique has potential application in research and could be clinically applicable in the treatment of senile macular degeneration.

Animals↗
PubMed1989

Heterosexual sexual behaviour in a sample of homosexually active men.

Three hundred and fifty six homosexually active men were recruited in 1988 for a study by interview of sexual behaviour. Thirty two per cent had homosexual passive anal sex in the previous month and 60% in the year before interview. Anal sex and unprotected anal sex were more common with regular than non-regular partners. Heterosexual sex was reported by 4% of men in the last month and 10% for the last year. Sixteen per cent of heterosexually active men reported anal sex with a female partner. Fewer men described themselves as bisexual than would be expected from the sample's recent sexual histories. More attention is needed to the definition and measurement of "bisexuality" to understand its role in HIV transmission.

Adolescent↗
PubMed1989

Assessment of corneal wound repair in vitro.

The time course for the closure of linear wounds produced in cultured cell monolayers following either mechanical debridement or excimer laser photoablation were compared. Wounds were produced in the central zone of a confluent layer of bovine corneal epithelial cells, keratocytes, or endothelial cells, and the residual area of the wound measured at regular intervals. Differences in the rate of wound closure between cell types were demonstrated. For epithelial cells the rate of resurfacing after mechanical or excimer laser damage was similar; for keratocytes there was a lag period before cell slide began after laser injury, but the subsequent rate of resurfacing was then similar to mechanical wounds; only for endothelial layers was a significantly reduced rate of closure observed after photoablation as compared to mechanical wounding. In this model of wound healing it appears that it is the mechanism of removal of the extracellular matrix formed by endothelial cells that produces the major difference in the rate of wound closure between mechanical injury or photoablation.

Animals↗
PubMed1989

The formation of autofluorescent granules in cultured human RPE.

Although the incomplete degradation of phagocytosed outer segment discs is thought to result in the formation of lipofuscin, there has to date been no proof of this concept. We report for the first time that cultured human retinal pigment epithelial (RPE) cells fed daily doses of isolated rod outer segments for periods of up to 3 months were capable of developing intracellular autofluorescent granules whose morphology and fluorescence characteristics were similar to lipofuscin. These autofluorescent granules were observed as early as 2 weeks following daily challenge with rod outer segments and the number of granules increased with the number of challenge doses until the experiment was terminated after 3 months of daily feeding. We also studied the effects of the antioxidant vitamin E and a drug, Centrophenoxine, which has been purported to slow the formation of lipofuscin formation in vivo. Neither of these additives given either with the challenge or subsequently had any effect on the formation of the intracellular granules. In conclusion, the development of these "lipofuscin-like" inclusions in cultured RPE may provide a model with which to study ageing processes and may provide an understanding of the increased lipofuscin accumulation observed in certain retinal pathologies.

Adolescent↗
PubMed1988

Retinal pigment epithelial cells in culture produce retinal vascular mitogens.

Conditioned medium from human retinal pigment epithelial cells in culture significantly stimulated the proliferation of subcultured bovine retinal capillary endothelial cells, pericytes, and freshly isolated retinal microvessels. The vascular mitogenic activity enhanced that of retinal crude extract. No evidence emerged of an inhibitor of microvascular cellular proliferation produced by retinal pigment epithelial cells.

Animals↗
PubMed1988

The cytoskeletal elements of human retinal pigment epithelium: in vitro and in vivo.

The cytoskeletal elements of normal (in situ) and cultured human retinal pigment epithelium (RPE) were studied by a variety of immunocytochemical techniques. Primary antibodies to vimentin and cytokeratins were used. Positive immunoreactivity for vimentin was obtained with in situ and cultured material. The pattern of reactivity obtained with antisera and monoclonals to cytokeratins was more complex. Cytokeratin immunoreactivity could be demonstrated in situ and in cultured cells. The pattern of cytokeratin expression was similar to that of simple or glandular epithelia. A monoclonal antibody that specifically recognizes cytokeratin 18 identified a population of cultured RPE cells that had particularly well-defined filamentous networks within their cytoplasm. Freshly isolated RPE was cytokeratin 18 negative by immunofluorescence, but upon culture cytokeratin 18 positive cells were identifiable. Cytokeratin 18 positive cells were identified in all RPE cultures (other than early primaries), regardless of passage number, age or sex of the donor. In post-confluent cultures cytokeratin 18 cells were identified growing over cytokeratin 18 negative cells, suggesting an association of cytokeratin 18 immunoreactivity with cell proliferation. Immunofluorescence studies of retinal scar tissue from two individuals revealed the presence of numerous cytokeratin 18 positive cells. These findings indicate that RPE cells can be identified by their cytokeratin immunoreactivity and that the overt expression of cytokeratin 18 may be associated with proliferation of human RPE both in vitro and in vivo.

Aged↗
PubMed1988

A microsystem to assay lysosomal enzyme activities in cultured retinal pigment epithelial cells.

A microsystem to assay the activity of lysosomal enzymes in a small number of cultured RPE cells is described. The activities of acid phosphatase, a-mannosidase, B-glucuronidase and N-acetyl-B-glucosaminidase were estimated in different human RPE cultures of varying passages. Some biochemical characteristics for each of the enzyme assays were studied including the effect of pH, the saturating concentrations of the appropriate substrates and the relationship between the enzyme activity and the number of cells assayed. The method presented is straightforward, avoids complicated tissue fractionation procedures and is able to estimate enzyme activities in as few as 10(4) cells.

Cells, Cultured↗
PubMed1988

Effects of vitreous from photocoagulated eyes on retinal microvascular cells in culture: a preliminary report.

Panretinal photocoagulation was carried out in mini pigs in an attempt to elucidate the mechanisms involved in laser therapy. The effect of the vitreous from these eyes on the proliferation of retinal microvascular endothelial cells was then studied. Vitreous removed 4 days after panretinal photocoagulation had no effect on the proliferation of bovine retinal microvascular endothelial cells in basal medium but inhibited proliferation in growth medium. Control vitreous was mitogenic for the microvascular cells in basal medium but this effect was not observed in growth medium.

Animals↗
PubMed1987

Growth of retinal capillary endothelia using pericyte conditioned medium.

Long-term cultures of bovine retinal capillary endothelial cells (BRCEC) have been established using bovine retinal pericyte conditioned medium (PCM). PCM had greater mitogenic activity on BRCEC than unconditioned medium (P less than 0.01). The mitogenic activity of PCM was not cell specific since bovine Tenon's fibroblast conditioned medium also had significant activity. PCM's activity was not enhanced by heparin though it was additive to that of retinal crude extract.

Animals↗
PubMed1986

Human retinal pigment epithelial cells in the vitreous of the owl monkey.

Cultured human retinal pigment epithelium was injected into the vitreous of owl monkeys. The epithelial cells were derived from either a foetal or an adult cell line. The five monkeys which were injected with cultured foetal cells developed substantial vitreal membranes and had retinal detachment by 2 weeks, whereas the five monkeys with cultured adult cells did not develop detachments within the period of investigation, and vitreal membranes were insubstantial. An electron-microscopic, immunohistochemical and autoradiographic study was conducted on these eyes to investigate in detail the behaviour and intraocular effects of the injected cells.

Adult↗