Biomedical subjects
P Hiscott
Publications and source records attributed to P Hiscott.
Variation in epiretinal membrane components with clinical duration of the proliferative tissue.
Immunohistochemical investigations were conducted on surgically excised epiretinal membranes to determine how cellular and extracellular components of proliferative vitreoretinopathy membranes change with time. Specimens of less than four months' duration contained a significantly higher proportion of retinal pigment epithelial cells than later membranes. No association was found between membrane duration and the content of collagen subtypes I to IV and laminin, but 'early' specimens contained significantly more fibronectin than did 'late' membranes. Fibronectin and collagens I, III, and IV showed a variable relationship with glial cells and were most consistently associated with retinal pigment epithelial and fibroblast-like cells. These observations may explain some of the surgical features of epiretinal membranes.
Cellular components of subretinal membranes in proliferative vitreoretinopathy.
To determine the cellular composition of subretinal membranes in proliferative vitreoretinopathy, surgically excised membranes were studied using electron microscopic and immunohistochemical procedures. Light microscopic immunohistochemistry was found to be superior to conventional electron microscopy as a means of evaluating the relative contributions of retinal pigment epithelium and glia to subretinal membranes. The cells of subretinal membranes chiefly comprised retinal pigment epithelium while glial cells were either absent or contributed only a minor component. It is proposed that the clinical properties of subretinal membranes in proliferative vitreoretinopathy derive from their retinal pigment epithelial cell element.
Inflammation and the formation of epiretinal membranes.
In this review of the literature evidence is provided from clinical, histological and experimental sources that inflammatory processes play a central role in the pathogenesis of contractile epiretinal membranes and proliferative vitreoretinopathy.
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.
Solitary astrocytic hamartoma simulating retinoblastoma.
The clinical, ultrasonographic and histopathological features (including immunohistochemistry and transmission electron microscopy) are described in a solitary astrocytic hamartoma of the retina in a 3-year-old child who was otherwise normal. Focal calcification was detected by ultrasound and this contributed to a misdiagnosis of retinoblastoma. The small tumour was located within the nerve fibre layer at the posterior pole and consisted solely of uniformly distributed astrocytes with benign cytological characteristics. Calcospherites were found within the cytoplasm of the astrocytes. Vascular abnormalities included intimal fibroplasia of arterioles with calcification of the internal elastic lamina and widespread endothelial proliferation; such abnormalities have not been previously noted in tumours with this degree of differentiation. The histological features are compared with those in previous reports of this rare tumour.
An unusual presentation of neurofibroma of the oculomotor nerve. Case report.
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Multiple aneurysms of the distal posterior inferior cerebellar artery.
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Drug treatment of herpes zoster.
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Cultured human retinal pigment epithelial cells differentially express thrombospondin-1, -2, -3, and -4.
Thrombospondins are a family of at least five proteins (TSP-1 to -4 and cartilage oligomeric matrix protein or COMP) whose functions are indeterminate. Distribution differences between family members suggest each protein may have some distinct functions. The retinal pigment epithelium (RPE) has divers unusual roles for an epithelia and can produce TSP-1. However, the wide range of RPE activities suggests that, if different thrombospondin family members do have different functions, RPE may express thrombospondins additional to TSP-1. Therefore, we analysed expression of thrombospondin isoforms by RPE using reverse-transcription-linked polymerase chain reaction. Cultured cells exhibited differential expression of TSP-1 to -4; TSP-2 and TSP-4 appearing later in culture than TSP-1 and TSP-3. In situ RPE expressed mRNA for TSP-1 to -4. No COMP mRNA was detected in RPE. These observations suggest that thrombospondin isoforms are regulated differently by the cells and that these proteins may have different functions in the RPE.