Effect of melatonin and zinc on the immune response in experimental Toxoplasma retinochoroiditis.

OBJECTIVES: To investigate the possible effect of melatonin (MEL) and zinc on the immune response to Toxoplasma gondii retinochoroiditis in the rat model of infection and to establish the possible value of artificial MEL and/or zinc supplementation as adjunctive therapeutic agents in the treatment of T. gondii retinochoroiditis. METHODS: Eighty-four Sprague-Dawley male rats were divided into 12 equal groups. All groups, except controls were infected with T. gondii parasite by intraperitoneal injection. Combinations of zinc-deficient diet, pinealectomy (Px), and artificial zinc and MEL were supplied during a 1-month period. At the end of the experiment, retinal and choroidal total lymphocytes, CD3+, CD4+, and CD8+ cell numbers were counted in histological sections. RESULTS: The highest amount of cellular infiltration (lymphocytes, CD3+, CD4+, CD8+ cells) in the choroid and retina was detected in infected + MEL + zinc-treated rats, and the least amount of cellular infiltration was observed in Px + zinc-deficient diet-treated rats. Although single zinc or MEL supplementation had no significant impact on the cellular infiltration in the retina and choroid in Px rats, combined therapy significantly improved these responses. CONCLUSION: Artificial supplementation of MEL and zinc should be considered as an adjunctive therapy to classic treatment of Toxoplasma retinochoroiditis especially in immunosuppressed and elderly patients if our data are confirmed in a clinical setting.

Ocular Halicephalobus (syn. Micronema) deletrix in a horse.

Ocular contents from a horse with a 4-week history of severe unilateral uveitis were submitted for histopathologic examination. A severe unilateral granulomatous chorioretinitis with intralesional Halicephalobus deletrix was diagnosed. The horse developed progressive neurologic signs several days following the surgery to remove ocular contents and implant a prosthesis and was subsequently euthanatized. A severe multifocal granulomatous encephalitis with intralesional H. deletrix, localized primarily to the optic chiasm, thalamus, and brain stem, was diagnosed from tissues acquired at necropsy. The other eye was not affected. This is the first report of ocular parasitism by H. deletrix and suggests possible systemic dissemination from a primary site in the eye.

[High-dosage combination antibiotic treatment in severe therapy-resistant uveitis and necrotizing (chorio)retinitis]. / Hochdosierte antibiotische Kombinationsbehandlung bei schweren therapierefraktären Uveitiden und nekrotisierenden (Chorio-) Retinitiden.

Twelve patients with extremely severe uveitis and two patients with necrotizing (chorio-)retinitis were treated with a combination of antibiotics consisting of penicillin G, gentamicin and metronidazole. The antibiotics were administered in 5 cases (all uveitis patients) after unsuccessful long-term treatment with other drugs, in nine cases after short-term treatment with other drugs or immediately. The treatment was effective in 10 of the uveitis patients, including all 5 cases in which the previous treatment had been unsuccessful. In 2 cases it was ineffective. It was effective, however, in both of the cases of necrotizing (chorio-)retinitis. The duration of the required treatment with antibiotics was not significantly prolonged in cases which had previously undergone long-term treatment with other drugs. However, the clinically detectable onset of improvement of vision and of the findings was significantly delayed. Despite some cogent connections between the antibiotics therapy and the improvement in the clinical picture, no well-founded conclusions as to etiology can be derived for the uveitis or necrotizing (chorio-)retinitis patients in question. The successful treatment of problematic cases identifies therapy with antibiotics as a therapeutic alternative.