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Biomedical subjects

P D Gormley

Publications and source records attributed to P D Gormley.

9 recordsLinked to original sources
PubMed1999

Retinochoroiditis is induced by oral administration of Toxoplasma gondii cysts in the hamster model.

Administration of Toxoplasma cysts by intraperitoneal innoculation in the Syrian Golden Hamster provides a reproducible animal model of acquired Toxoplasmic retinochoroiditis and cysts are observed in the brain. However, toxoplasmosis is frequently acquired by oral ingestion of contaminated foodstuffs and it is recognised that the route by which disease is acquired may influence its pathogenesis and clinical expression. This study aimed to determine whether retinochorioiditis and cysts in the brain develop after oral ingestion in the Syrian Golden Hamster model as this is the route of induction akin to that in man and may therefore be more relevant in the study of disease pathogenesis. All animals developed disease by 4 weeks. Ocular and cerebral inflammation was confirmed by histology at 16 weeks and this was milder than in the original model.

Administration, Oral↗
PubMed1999

Choroidal tuberculosis diagnosed by polymerase chain reaction. A clinicopathologic case report.

PURPOSE: To show the use of the polymerase chain reaction (PCR) in a granulomatous choroidal lesion to support a diagnosis of tuberculosis. DESIGN: Observational case report. TESTING: Nucleic acid target amplification of a choroidal specimen using PCR for detection of Mycobacterium tuberculosis was tested. MAIN OUTCOME MEASURES: Positive nucleic acid target amplification for M. tuberculosis in the ocular sample was measured. RESULTS: PCR was positive for M. tuberculosis with appropriate negative controls. CONCLUSIONS: PCR was thought to be a useful supportive technique in the diagnosis of choroidal tuberculosis.

Choroid Diseases↗
PubMed1999

Incidence of symptomatic toxoplasma eye disease: aetiology and public health implications.

Ocular disease is the commonest disabling consequence of toxoplasma infection. Incidence and lifetime risk of ocular symptoms were determined by ascertaining affected patients in a population-based, active reporting study involving ophthalmologists serving a population of 7.4 million. Eighty-seven symptomatic episodes were attributed to toxoplasma infection. Bilateral visual acuity of 6/12 or less was found in seven episodes (8%) and was likely to have been transient in most cases. Black people born in West Africa had a 100-fold higher incidence of symptoms than white people born in Britain. Only two patients reported symptoms before 10 years of age. The estimated lifetime risk of symptoms in British born individuals (52% of all episodes) was 18/100000 (95% confidence interval: 10.8-25.2). The low risk and mild symptoms in an unscreened British population indicate limited potential benefits of prenatal or postnatal screening. The late age at presentation suggests a mixed aetiology of postnatally acquired and congenital infection for which primary prevention may be appropriate, particularly among West Africans.

Adolescent↗
PubMed1998

Effects of drug therapy on Toxoplasma cysts in an animal model of acute and chronic disease.

PURPOSE: To evaluate the effects of drug therapy on the clinical course of acute acquired Toxoplasma retinochoroiditis and on the number of Toxoplasma cysts present in the brain and ocular tissues in the hamster animal model. METHODS: The Syrian golden hamster animal model of Toxoplasma retinochoroiditis was used. In acute disease, systemically administered atovaquone was compared with conventional therapies (pyrimethamine combined with sulfadiazine; clindamycin; and spiramycin). The clinical course of the ocular disease was determined with retinal examination and photography of the fundus. The number of Toxoplasma cysts remaining after treatment was evaluated in aliquots of brain homogenate and in retinal tissue. The effect of atovaquone on cerebral Toxoplasma cyst count was also studied in chronic disease. RESULTS: None of the drugs administered altered the course of the acute disease, judged by clinical examination. Atovaquone alone significantly reduced the number of cerebral Toxoplasma cysts after acute disease. Atovaquone also significantly reduced the cerebral Toxoplasma cyst count in chronic disease. CONCLUSIONS: Tissue cysts are believed to be responsible for reactivation of Toxoplasma retinochoroiditis. Atovaquone has the potential to reduce the risk of recurrent disease.

Acute Disease↗
PubMed1997

Phenotypic analysis of resident lymphoid cells in the conjunctiva and adnexal tissues of rat.

The conjunctival associated lymphoid tissue is considered to be an integral part of the mucosal immune system. Under normal circumstances immune mechanisms in mucosal associated lymphoid tissue of the gut and bronchus can selectively suppress, rather than enhance, immune responsiveness to encountered antigens, inducing a state of tolerance. It is possible that conjunctival associated lymphoid tissue can also induce a state of tolerance to encountered antigens. Such a response may be exploited to modulate immune mediated ocular disease. Enhanced tolerance may protect the host against foreign antigen. Alternatively, under certain circumstances when the normal immune system is altered or disrupted the mucosal tissue may act to induce sensitisation and trigger immune mediated disease. The rat is frequently used as an animal model of immune mediated eye disease, but the normal profile of immune cells in the rat conjunctiva has not been studied. This information is essential for meaningful interpretation in the experimental situation. In this study we examined the immunophenotype of lymphoid tissue associated with the conjunctiva, lacrimal gland and Harderian gland of the Lewis rat. CD4+, Ia+ and the monocyte/macrophage population of cells were found predominantly in the substantia propria of the conjuctiva and interstitial connective tissue of the glands. CD8+ cells were distributed mainly in relation to the conjunctival and glandular epithelium. Goblet cells stained strongly with the monoclonal antibody (MAb) MRC OX-39, which is a marker for IL-2 receptors. The overall pattern of distribution of immunocompetent cells in the rat was found to be similar to that reported in humans.

Animals↗
PubMed1997

The sphenoidal sinus in optic nerve decompression.

Surgical decompression of the orbit may be necessary in dysthyroid patients with compressive optic neuropathy. Two-wall decompression with a trans-antral or a trans-conjunctival approach is commonly used. However, in some patients the initial improvement following this surgical procedure is not maintained. Although this may be due to disease progression, a variant of orbital anatomy can contribute to sub-optimal decompression. We report three cases in which recurrence of compressive optic neuropathy occurred following two-wall decompression. The sphenoidal sinus was placed anteriorly in these patients. Further decompression which included the lateral wall of the sphenoidal sinus resulted in improvement. An endoscopic approach provides superior access and visibility for decompression of the optic nerve into the sphenoidal sinus, and this approach may be the surgical treatment of choice in these cases.

Adult↗
PubMedDate not supplied

Lymphocyte subsets in conjunctival mucosa-associated-lymphoid-tissue after exposure to retinal-S-antigen.

PURPOSE: To evaluate the immune cell subsets in conjunctival mucosa-associated-lymphoid-tissue (C-MALT) following challenge with antigen. METHODS: Ten adult female Lewis rats were studied. Five rats received one drop (5 microL) of retinal S-antigen (500 microg/mL in phosphate buffered saline, PBS) instilled into the lower fornix twice daily for 10 consecutive days. Five rats received PBS only and served as controls for the experiment. Two days after the last instillation the animals were sacrificed and the orbital contents prepared for immunohistological staining. A panel of monoclonal antibodies was used: CD5, CD4, CD8, CD25, and CD45RA. The number of positive cells were counted in sections of epibulbar, forniceal, and tarsal conjunctiva. RESULTS: There was a significant increase in the number of CD8+ T lymphocytes in the conjunctiva of animals receiving retinal S-antigen when compared to control animals. CONCLUSION: Conjunctival instillation of retinal S-antigen causes an immune response in the C-MALT with a significant increase in the CD8+ T lymphocyte subset in this tissue. This response may be involved in the induction of tolerance to the encountered antigen.

Animals↗