Premotor and occipital theta asymmetries as discriminators of memory- and stimulus-guided tasks

The saccadic paradigm has been used to investigate specific cortical networks involving visuospatial attention. We examined whether asymmetry in theta and beta band differentiates the role of the hemispheres during the execution of two different prosacadic conditions: a fixed condition, where the stimulus was presented at the same location; and a random condition, where the stimulus was unpredictable. Twelve healthy volunteers (3 male; mean age: 26.25) performed the task while their brain activity pattern was recorded using quantitative electroencephalography. We did not find any significant difference for beta, slow- and fast-alpha frequencies for the pairs of electrodes analyzed. The results for theta band showed a superiority of the left hemisphere in the frontal region when responding to the random condition on the right, which is related to the planning and selection of responses, and also a greater activation of the right hemisphere during the random condition, in the occipital region, related to the identification and recognition of patterns. These results indicate that asymmetries in the premotor area and the occipital cortex differentiate memory- and stimulus-driven tasks. (C) 2011 Elsevier Inc. All rights reserved.

Surfactant-assisted intercalation of high molecular weight poly(ethylene oxide) into vanadyl phosphate di-hydrate

A high molecular weight poly(ethylene oxide)/layered vanadyl phosphate di-hydrate intercalation compound was synthesized via the surfactant-assisted approach. Results confirmed that surfactant molecules were replaced with the polymer, while the lamellar structure of the matrix was retained, and that the material presents high specific surface area. In addition, intercalation produced a more thermally stable polymer as evidenced by thermal analysis. (C) 2011 Elsevier Ltd. All rights reserved.

C-Phycocyanin protects SH-SY5Y cells from oxidative injury, rat retina from transient ischemia and rat brain mitochondria from Ca2+/phosphate-induced impairment

Oxidative stress and mitochondrial impairment are essential in the ischemic stroke cascade and eventually lead to tissue injury. C-Phycocyanin (C-PC) has previously been shown to have strong antioxidant and neuroprotective actions. In the present study, we assessed the effects of C-PC on oxidative injury induced by tert-butylhydroperoxide (t-BOOH) in SH-SY5Y neuronal cells, on transient ischemia in rat retinas, and in the calcium/phosphate-induced impairment of isolated rat brain mitochondria (RBM). In SH-SY5Y cells, t-BOOH induced a significant reduction of cell viability as assessed by an MTT assay, and the reduction was effectively prevented by treatment with C-PC in the low micromolar concentration range. Transient ischemia in rat retinas was induced by increasing the intraocular pressure to 120 mmHg for 45 min, which was followed by 15 min of reperfusion. This event resulted in a cell density reduction to lower than 50% in the inner nuclear layer (INL), which was significantly prevented by the intraocular pre-treatment with C-PC for 15 min. In the RBM exposed to 3 mM phosphate and/or 100 mu M Ca2+, C-PC prevented in the low micromolar concentration range, the mitochondrial permeability transition as assessed by mitochondrial swelling, the membrane potential dissipation, the increase of reactive oxygen species levels and the release of the pro-apoptotic cytochrome c. In addition, C-PC displayed a strong inhibitory effect against an electrochemically-generated Fenton reaction. Therefore, C-PC is a potential neuroprotective agent against ischemic stroke, resulting in reduced neuronal oxidative injury and the protection of mitochondria from impairment. (C) 2012 Elsevier Inc. All rights reserved.

Inflammatory responses in the rat superior colliculus after eye enucleation

Ocular enucleation induces profound morphological alterations in central visual areas. However, little is known about the response of glial cells and possible inflammatory processes in visual brain areas resulting from eye enucleation. In this study, immunoblotting and immunostaining assays revealed increased expression of astrocyte and microglia markers in the rat superior colliculus (SC) between 1 and 15 days after contralateral enucleation. A transient increase of neuronal COX-2 protein expression was also found in the SC. To evaluate the role of an anti-inflammatory drug in attenuating both COX-2 and glial cell activation, the synthetic glucocorticoid dexamethasone (DEX) was administered (1mg/kg i.p., for 3 days) to enucleated rats. Immunoblotting data revealed that DEX treatment significantly inhibited COX-2 protein expression. Postlesion immunostaining for astrocyte and microglia markers was also significantly reduced by DEX treatment. These findings suggest that the removal of retinal ganglion cell input generates inflammatory responses in central retinorecipient structures