PhTx3-4, a Spider Toxin Calcium Channel Blocker, Reduces NMDA-Induced Injury of the Retina.

The in vivo neuroprotective effect of PhTx3-4, a spider toxin N-P/Q calcium channel blocker, was studied in a rat model of NMDA-induced injury of the retina. NMDA (N-Methyl-D-Aspartate)-induced retinal injury in rats reduced the b-wave amplitude by 62% ± 3.6%, indicating the severity of the insult. PhTx3-4 treatment increased the amplitude of the b-wave, which was almost equivalent to the control retinas that were not submitted to injury. The PhTx3-4 functional protection of the retinas recorded on the ERG also was observed in the neuroprotection of retinal cells. NMDA-induced injury reduced live cells in the retina layers and the highest reduction, 84%, was in the ganglion cell layer. Notably, PhTx3-4 treatment caused a remarkable reduction of dead cells in the retina layers, and the highest neuroprotective effect was in the ganglion cells layer. NMDA-induced cytotoxicity of the retina increased the release of glutamate, reactive oxygen species (ROS) production and oxidative stress. PhTx3-4 treatment reduced glutamate release, ROS production and oxidative stress measured by malondialdehyde. Thus, we presented for the first time evidence of in vivo neuroprotection from NMDA-induced retinal injury by PhTx3-4 (-ctenitoxin-Pn3a), a spider toxin that blocks N-P/Q calcium channels.

Oclusão de artéria central da retina associada ao forame oval patente / Central retinal artery occlusion associated with patent foramen ovale

Oclusão da artéria central da retina é uma doença comumente encontrada em pacientes idosos, mas pode também ser vista em crianças e adultos jovens. Nestes, as principais causas são anomalias cardíacas, sendo o forame oval patente o mais observado. O objetivo do trabalho é relatar o caso de um paciente jovem com oclusão da artéria central da retina apresentando persistência de forame oval e, também, salientar a importância de uma propedêutica detalhada nos casos de oclusões vasculares da retina.

Central retinal artery occlusion it’s a disease most encountered in older patients, however it can be seen in children and young persons. In this situation the principal causes are cardiac abnormalities, and the patent foramen ovale is the most observed. The purpose of this study is to report a case of central retinal artery occlusion in a young patient with patent foramen ovale and, also, describe the importance of a detailed management in cases of retinal vascular occlusions.

Phoneutria spider toxins block ischemia-induced glutamate release and neuronal death of cell layers of the retina.

PURPOSE: To investigate the effect of calcium channel blockers, spider toxins, on cell viability and the glutamate content of ischemic retinal slices. METHODS: Rat retinal slices were subjected to ischemia via exposure to oxygen-deprived low-glucose medium for 45 minutes. Slices were either treated or not treated with the toxins PhTx3, Tx3-3, and Tx3-4. After oxygen-deprived low-glucose insult, glutamate content and cell viability were assessed in the slices by confocal and optical microscopy. RESULTS: In the retinal ischemic slices that were treated with PhTx3, Tx3-3, and Tx3-4, confocal imaging showed a decrease in cell death of 79.5 ± 3.1%, 75.5 ± 5.8%, and 61 ± 3.8%, respectively. Neuroprotective effects were also observed 15, 30, 60, and 90 minutes after the onset of the retinal ischemic injury. As a result of the ischemia, glutamate increased from 6.2 ± 1.0 nMol/mg protein to 13.2 ± 1.0 nMol/mg protein and was inhibited by PhTx3, Tx3-3, and Tx3-4 to 8.6 ± 0.7, 8.8 ± 0.9, and 7.4 ± 0.8 nMol/mg protein, respectively. Histologic analysis of the live cells in the outer, inner, and ganglion cell layers of the ischemic slices showed a considerable reduction in cell death by the toxin treatment. CONCLUSION: Spider toxins reduced glutamate content and cell death of retinal ischemic slices.

Estudo comparativo entre oclusão e não-oclusão no tratamento de abrasão corneana após retirada de corpo estranho da córnea / Comparative study between eyepad and no eyepad in the treatment of corneal abrasion secondary to removal of corneal foreign body

OBJETIVO: Comparar a eficácia entre duas modalidades de tratamento das abrasões corneanas após a retirada de corpo estranho da córnea: curativo oclusivo e sem curativo. MÉTODOS: Cinqüenta e quatro pacientes com abrasão corneana após retirada de corpo estranho foram randomizados, de forma alternada, em dois grupos: um grupo com curativo oclusivo e o outro sem curativo. Os pacientes foram avaliados diariamente até a cura, em relação aos seguintes parâmetros: área da abrasão corneana, intensidade de dor, presença de fotofobia, lacrimejamento, sensação de corpo estranho e visão turva. RESULTADOS: Não houve diferença estatisticamente significativa entre os dois grupos quanto a: área da abrasão corneana, tempo para se obter a cura, dor, fotofobia, lacrimejamento, sensação de corpo estranho e visão turva. Não ocorreu nenhuma complicação ocular ou sistêmica durante o tratamento em ambos os grupos. CONCLUSAO: Abrasão corneana após retirada de corpo estranho, menor que 9 mm² , pode ser tratada apenas com antibiótico tópico de largo espectro e colírio cicloplégico, sem a necessidade do curativo oclusivo, tornando o tratamento mais simples e menos dispendioso.