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Biomedical subjects

A C McCartney

Publications and source records attributed to A C McCartney.

At least 37 records · Page 2Linked to original sources
PubMed1995

The distribution of fibronectin and P component in Descemet's membrane: an immunoelectron microscopic study.

Descemet's membrane consists of two zones, the 'anterior banded zone' which contains wide-spaced collagen and the amorphous 'posterior non-banded zone'. It is attached anteriorly to the corneal stroma by a narrow transitional zone termed the 'interfacial matrix'. The distribution of fibronectin and P component within the different layers of Descemet's membrane was investigated using an ultrastructural immunogold technique. Seven normal human corneas from an eye bank and one specimen from an orbital exenteration were examined. Fibronectin was predominantly present in the posterior part of the posterior non-banded zone and in the anterior banded zone. The anterior part of the posterior non-banded zone contained less fibronectin. P component was present throughout the anterior banded and posterior non-banded zones. There was a sharp demarcation at the interfacial matrix since neither substance was observed in the corneal stroma. The differences shown in the distribution of fibronectin and P component within Descemet's membrane may have resulted from their binding to other substances or alternatively from differences in the quantities laid down during the evolution of this basement membrane.

Descemet Membrane↗
PubMed1995

Pathology of the iridocorneal-endothelial syndrome. The ICE-cell.

PURPOSE: The iridocorneal-endothelial (ICE) syndrome is characterized by glaucoma, corneal failure, and iris destruction. Specular photomicroscopy of the corneal endothelium in this disease shows a population of abnormal cells named ICE-cells. Comparison between ultrastructural examination and specular photomicroscopy demonstrates that the histologic equivalent of ICE-cells are cells with an epithelial phenotype. The authors have studied the differentiation markers expressed by ICE-cells using an ultrastructural immunocytochemical technique. METHODS: Seven keratoplasty specimens from patients with the ICE syndrome were examined by scanning and transmission electron microscopy and light and electron microscopic immunocytochemistry. Comparison was made with three normal corneas. Immunocytochemical studies were performed with monoclonal antibodies to broad-spectrum cytokeratins, cytokeratins 3, 5/8, 8/18 and 19, vimentin, and epithelial membrane antigen. RESULTS: ICE-cells were morphologically similar to epithelial cells and expressed the same profile of differentiation markers as did normal limbal epithelial cells. CONCLUSIONS: ICE-cells may arise from an embryologic ectopia of ocular surface epithelium. Alternatively, these findings are consistent with a metaplastic stimulus resulting in a profound change in the phenotype of normal corneal endothelial cells.

Adult↗
PubMed1994

A case report of Mycobacterium chelonae keratitis and a review of mycobacterial infections of the eye and orbit.

Mycobacteria are unusual causes of keratitis and other ocular infections but the outcome of infection is often serious. We report a case of keratitis due to Mycobacterium chelonae, a rapidly growing environmental mycobacterium, in a soft contact-lens wearer, and discuss the difficulty and delay in identifying the organism, twice erroneously identified as Nocardia asteroides on morphological grounds. Despite in vitro susceptibility, the response to anti-bacterial agents was negligible and a second keratoplasty was required after a recurrence of disease at the donor-host junction. We review the role of mycobacteria as the cause of keratitis and other forms of ocular disease.

Adult↗
PubMed1994

Granular corneal dystrophy. Visual results and pattern of recurrence after lamellar or penetrating keratoplasty.

BACKGROUND: Granular corneal dystrophy is a rare indication for corneal transplantation. Both penetrating and lamellar keratoplasty have been recommended, but because granular corneal dystrophy is known to recur within the donor material and multiple grafts may be necessary, the best surgical option has not been clearly established. The cellular cause of the dystrophy is unknown and the authors hypothesized that the rate and pattern of recurrence within lamellar and penetrating grafts might give clues to its etiology. METHODS: The authors compared the visual outcome, rate, and pattern of recurrence after 20 penetrating keratoplasties and 11 lamellar keratoplasties for granular corneal dystrophy. RESULTS: Penetrating keratoplasty and lamellar keratoplasty have a good visual outcome in granular corneal dystrophy. Visual acuities after both procedures were not statistically different. Recurrence of the dystrophy within the graft material was almost universal within 4 years. It first appeared centrally and superficially, occasionally adopting a vortex pattern suggesting epithelial involvement. The recurrence-free interval was independent of size and type of graft performed. CONCLUSION: The authors recommend lamellar keratoplasty as a primary procedure in managing visually disabling granular corneal dystrophy if the deposits are limited to the superficial cornea. This is particularly applicable in younger patients in whom multiple procedures may be necessary over a lifetime due to recurrence of the dystrophy, and the lower morbidity rate associated with lamellar keratoplasty becomes appreciable. Although granular corneal dystrophy generally is classified as a stromal dystrophy, the pattern of recurrence is more consistent with an epithelial or tear-borne abnormality than a disease of the stromal keratocyte.

Adolescent↗
PubMed1994

Prognostic factors in primary malignant melanoma of the conjunctiva: a clinicopathological study of 256 cases.

A series of 256 consecutive cases of invasive primary conjunctival malignant melanomas was examined to identify clinical and histopathological prognostic factors. The follow up period varied between 0.3 and 45.9 years (mean 9 years, median 6.3 years). The 5 year survival rate was estimated at 82.9%, the 10 year survival rate at 69.3%. Multiple regression analysis with the Cox proportional hazards model was used to assess sex, age, and a number of baseline features of conjunctival malignant melanoma as possible prognostic factors influencing melanoma related mortality. In assessing each potential prognostic factor, the effects of all other factors were taken into account in the modelling process. Tumours in unfavourable locations--that is, those involving the palpebral conjunctiva, fornices, plica, caruncle, and lid margins, were associated with 2.2 times higher mortality compared with (epi)bulbar melanomas. Patients with mixed cell type tumours had about three times higher mortality compared with those with pure spindle cell melanomas, and histological evidence of lymphatic invasion by tumour cells was also a prognostic feature, carrying a fourfold increase in the death rate. Multifocal tumours were associated with a fivefold increase in mortality among those with tumours in favourable (epi)bulbar locations, but were not prognostic in patients with melanomas in unfavourable sites. The death rate was significantly higher in those with initial tumour thickness of more than 4 mm, but only among patients with unfavourably located melanomas. Sex, age, and clinical origin of the tumour (primary acquired melanosis, pre-existing naevus, or de novo) were not useful prognostic indicators in this study.

Adult↗
PubMed1994

Orbital exenteration in 95 cases of primary conjunctival malignant melanoma.

The role of orbital exenteration in the management of malignant melanoma of the conjunctiva has been underexplored. The outcome in 95 patients with this condition, who underwent exenteration as a primary treatment (n = 36) or after failure of other treatment (n = 59) for early to advanced stages of the disease, was evaluated. The majority of treated cases had multicentric melanomas sited at prognostically unfavourable locations. In the group of tumours with a maximum thickness of 1.0 mm no melanoma related mortality was noted. Melanomas thicker than 1.0 mm were associated with a mortality varying between 33% and 50%, independent of whether exenteration was performed as primary or secondary treatment. An especially poor outcome was noted for the group of caruncular melanomas despite exenteration. These findings indicate that total eradication of tumour should be performed at an early stage. For this purpose, a combination of debulking surgery and adjunctive cryotherapy or beta radiotherapy is more appropriate than orbital exenteration which causes disfigurement and blindness. Exenteration of the orbit should be reserved as a palliative procedure for advanced stages of neoplastic disease.

Adult↗
PubMed1994

Quantitative morphology of human retrolaminar optic nerve vasculature.

PURPOSE: To quantify the variation in the blood supply of the retrolaminar optic nerve in humans. The retrolaminar anterior optic nerve is supplied by an elliptical arterial "circle" of Haller and Zinn formed by anastomoses around the optic nerve between medial and lateral paraoptic short posterior ciliary arteries (PO-SPCAs). The frequency with which complete perioptic nerve arteriolar anastomoses (PONAA) occur is unknown, yet they form the basis for many postulated pathophysiological mechanisms. METHODS: Scanning electron microscopy was performed on 25 orbital and ocular microvascular corrosion casts (methyl methacrylate) from 20 human cadavers of subjects 21 to 97 years of age without known ocular disease. RESULTS: Eighteen casts were examined in detail after microdissection (the analysis of seven casts was limited because of their fragility). In 15/18 (83%) casts, the PONAA were supplied by branches of a medial and lateral PO-SPCA; in 2/18, they were supplied by one (lateral) PO-SPCA; and in 1/18, they were supplied by a superior PO-SPCA and two horizontal PO-SPCAs. The PONAA had intact superior and inferior anastomoses in 8/18 (44%) casts, anastomoses with narrowed portions in 6/18 (33%), and incomplete in 4/18 (23%). Narrowed portions were not preferentially distributed to either superior or inferior anastomoses. CONCLUSIONS: Complete PONAA was found in more than 75% of casts, including anastomoses with narrow portions in 33% of casts.

Adult↗
PubMed1993

Ocular and neurological Behçet's disease without orogenital ulceration?

A 28 year old West Indian patient is described who had a relapsing and remitting steroid-sensitive illness for 3 years. The clinical features included uveitis and widespread CNS involvement. The patient was treated as though he had neurosarcoidosis. Post mortem examination revealed histological changes compatible with a diagnosis of Behçet's disease, but at no time did he suffer from oral or genital ulceration or arthritis. The authors suggest a new term to encompass such an entity: the "Behçet's MINUS" syndrome (multifocal intermittent neurological and uveitic syndrome).

Adult↗
PubMed1992

The ocular pathology of Norrie disease in a fetus of 11 weeks' gestational age.

The ocular pathology of Norrie disease was studied for the first time in a fetus of 11 weeks' gestation, following prenatal diagnosis using genetic markers for Norrie disease and elective abortion. The eyes were histologically normal, with no evidence of primary neuroectodermal maldevelopment of the retina, previously postulated to be the cause of the ocular changes. We believe that the retinal and other manifestations of Norrie disease are the result of a primary abnormality of vascular proliferation, probably in relation to persistent hyperplastic primary vitreous after approximately 14 weeks' gestation. We postulate that the ocular and otological effects of Norrie disease may be due to a genetically mediated abnormality of secretion of, or sensitivity to, angiogenic growth factors at endodermal-neuroectodermal interfaces during fetal and postnatal development.

Abortion, Legal↗
PubMed1992

Spontaneous congenital non-pigmented epithelial cysts of the iris stroma.

Histopathological and immunohistochemical findings in 11 patients with spontaneous congenital non-pigmented epithelial cysts of the iris stroma were studied. The cysts were lined by stratified squamous to unilayered cuboidal non-pigmented epithelium. Goblet cells were present in nine cysts, indicating a similarity to conjunctival epithelium. The demonstration of higher-molecular-weight keratins and absence of S-100 protein, by monoclonal and polyclonal antibodies, argues for surface ectodermal rather than neuroectodermal origin of the cysts. Theories of embryogenesis have been conflicting, but our results support the theory that they arise from surface ectoderm, displaced probably at the time of lens vesicle formation. The finding of normally sited subepithelial S-100 positive melanocytes may suggest that ectopic conjunctival epithelium can induce normal patterns of migration of neural crest cells.

Adolescent↗
PubMed1992

AgNOR counts in conjunctival malignant melanoma lack prognostic value.

Using a silver staining technique, argyrophilic nucleolar organiser region-associated proteins (AgNORs) have been studied in routinely processed paraffin sections of 46 invasive malignant melanomas (MM) of the conjunctiva. The aim of this retrospective study was to assess the value of the AgNOR method as a prognostic indicator for this neoplasm. The 46 cases were divided into two groups: (A) 14 cases of MM that metastasised and caused death of the patient within 5 years of (histological) diagnosis, and (B) 32 cases of MM that did not metastasise and in which patients survived beyond 5 years. The mean of the AgNOR counts per nucleus was 7.03 (95% CI: 5.81-8.24) in group A, and 7.15 (95% CI: 6.53-7.77) in group B. A comparison using a multifactor analysis of variance (ANOVA) model, which corrected for possible confounding effect of tumour thickness, site, and cell type showed no significant difference in AgNOR counts between groups A and B (p = 0.8). Analysis by the Cox proportional hazards regression model showed that survival was not influenced significantly by the mean AgNOR number (hazard ratio: 0.92). Whereas the AgNOR technique may be used to distinguish benign from malignant melanocytic lesions of the conjunctiva, we conclude it has no value in predicting the outcome for patients with conjunctival MM.

Cell Count↗
PubMed1992

Horner's syndrome: an electron microscopic study of a human iris.

Electron microscopy was performed on the irides of a man with a history of a long standing Horner's syndrome which resulted in iris heterochromia. Comparison of his normal brown iris with the depigmented blue iris showed depletion of anterior border cells and absence of sympathetic nerve fibres. Stromal melanocyte numbers were also diminished but melanosome numbers within the residual cells were not significantly different. Postnatal maintenance of stromal and anterior border zone pigmentation, derived from the neural crest, would appear to be dependent on an intact sympathetic nerve supply in contrast to the iris pigment epithelium which remains normally unaffected in Horner's syndrome.

Adrenergic Fibers↗
PubMed1992

Premalignant melanosis of the conjunctiva and the cornea in xeroderma pigmentosum.

Xeroderma pigmentosum is a rare autosomal recessive dermatosis. The neoplastic changes in sunlight-exposed areas of the skin and eyes may be related to the impaired replication of ultraviolet radiation-damaged DNA. A 38-year-old Greek woman is reported with a mild form of xeroderma pigmentosum and primary acquired melanosis with atypia of her right limbal conjunctiva and cornea. The development of this precursor of conjunctival malignant melanoma in a xeroderma pigmentosum patient may support the putative role of sunlight exposure in malignant transformation of conjunctival melanocytes.

Adult↗
PubMed1992

Multifocal amelanotic conjunctival melanoma and acquired melanosis sine pigmento.

Clinical and histopathological features of four cases of multifocal amelanotic malignant melanoma of the conjunctiva in association with 'acquired melanosis sine pigmento' are reported. The absence of conjunctival pigmentation in this extremely rare combination of lesions prevented early diagnosis and clinical monitoring. As a result orbital exenteration was required in three cases. This multicentric non-pigmented variety of conjunctival malignant melanoma tends to present later than pigmented forms and may require exenteration of the orbit as a primary procedure.

Adult↗