Mario Saravia

Inducible nitric oxide synthase subserves cholinergic vasodilation in retina.

In this paper, we investigate the role of muscarinic acetylcholine receptor (mAChR) activity in the regulation of inducible (i) nitric oxide synthase (iNOS) expression and activity. The signaling pathway involved is also examined. These experiments also provide a link between mAChR activation and the nitric oxide (NO)-dependent regulation of retinal vascular diameter. The diameter of the retinal vessels at a distance of 1 disc diameter from the center of the optic disc was measured in rats using digital retinal photography, and both iNOS-mRNA gene expression and NOS were specifically measured using RT-PCR and [U-(14)C] citrulline assays, respectively. Stimulation of M(1) and M(3) mAChR with carbachol caused an increase in vessel diameter, in iNOS-mRNA levels and in NOS activity in the retina. Aminoguanidine, an inhibitor of iNOS, attenuated all these effects. Inhibitors of phospholipase C (PLC) and protein kinase C (PKC) but not calcium/calmodulin (CaM) prevented the muscarinic-dependent increase in iNOS-mRNA levels. The results obtained suggest that the activation of mAChR increases retinal vessel diameters by increasing the production of nitric oxide (NO) through iNOS activation and iNOS-mRNA gene expression. The mechanism appears to occur secondarily to stimulation of PLC and PKC enzymatic activity.

Endogenous Histoplasma capsulatum endophthalmitis in an immunocompetent patient

Purpose To report on a case of Histoplasma capsulatum endogenous endophthalmitis in an immunocompetent patient. Methods A 30-year-old patient was admitted with floaters and vision impairment of 1 months duration. He had a history of adrenal insufficiency, together with nasal, septum, and soft palate lesions of 3 months; duration. Culture results from specimens of these lesions were positive for H capsulatum. He was human immunodeficiency virus negative and there was no evidence of immunodepression or history of immunosuppression. Fundus examination revealed multiple fluffy balls with a string of pearls appearance, 2+ vitreous haze, multiple foci of retinochoroiditis inferiorly in the peripheral retina, and a 6-disk area lesion of retinochoroiditis at the superotemporal periphery. Due to poor response to oral itraconazole, a vitrectomy was performed with an intraocular injection of amphotericin B 5 μg/0.1 mL and removal for a vitreous specimen for culture of bacteria and fungi. Results Vitreous specimen culture of the yeast at 28°C grew a white filamentous fungus colony, which was again cultured in a brain heart infusion agar medium, where it developed hyaline septate hyphae with microconidia and circular macroconidia with double wall, which was stained with a lactophenol dye at microscopic examination. The macroscopic morphology was consistent with H capsulatum. Conclusions Although endogenous H capsulatum endophthalmitis is a rare entity, it should be considered as a possible etiology even in apparently immunocompetent hosts, especially in patients with history of disseminated disease.

Spectral optical coherence tomography findings in an elderly patient with syphilitic bilateral chronic panuveitis

Purpose To report the spectral domain optical coherence tomography (SD-OCT) features of a focal retinitis in an elderly male patient with bilateral syphilitic panuveitis. Observations In the left eye (LE), spectral domain SD-OCT images during the active period revealed hyperreflectivity extending through the full thickness of the retina with no individualization of the layers, except for the retinal pigment epithelium. Once the lesion healed, SD-OCT imaging revealed an inner retinal atrophy and a mild disruption of the retinal pigment epithelium. Conclusions and importance In our patient, treponemal infection seemed to produce full-thickness retinal damage with partial involvement of the retinal pigment epithelium. The severe retinal damage, in this case, led to a poorer visual outcome than in other forms of syphilitic retinal involvement.

The VEGF Paradox : Does diabetic retinopathy protect from age related macular degeneration?

Age-related macular disease (AMD) and diabetic retinopathy (DR) are prevalent diseases. Vascular endothelial growth factor (VEGF) related retinal neovascularization is a common feature in both. Consequently, both pathologies are treated with anti-VEGF therapy. We have previously reported a lower incidence of AMD in patients with DR compared to controls. The present study hypothesizes that DR in stages in which the concentration of intravitreal VEGF is increased, might have a protective role for both the onset and development of AMD.

FUSARIUM SOLANI SUBRETINAL ABSCESS IN A PATIENT WITH ACUTE MYELOID LEUKEMIA.

Purpose: To report on a case of Fusarium solani subretinal abscess in a patient with acute myeloid leukemia treated with an allogenic bone marrow transplant. Methods: A 47-year-old male with a history of acute myeloid leukemia with intermediate cytogenetic risk was admitted in our hospital. The disease relapsed after two cycles of chemotherapy. He was then treated with an allogenic bone marrow transplant, with busulfan, cyclophosphamide, and thymoglobulin. One week after the procedure, a sepsis of unknown origin in neutropenia occurred. Blood cultures and sputum were negative for bacteria and fungi. At the eighth week after the procedure, the patient had acute vision loss of the right eye. Funduscopy in the right eye revealed an inferior temporal yellowish white elevated lesion of approximately 10 disk areas and superficial perifoveal and perilesional hemorrhages. Results: Vitrectomy was performed and samples from the vitreous and the subretinal abscess material were sent for analysis. Vitreous and subretinal specimens grew colonies of a fungus morphologically consistent with F. solani. Conclusion: Fusarium solani should be included in the differential diagnosis of subretinal abscesses.