Early and late neuropathological features of meningoencephalitis associated with Maraba virus infection

Maraba virus is a member of the genus Vesiculovirus of the Rhabdoviridae family that was isolated in 1983 from sandflies captured in the municipality of Maraba, state of Pará, Amazônia, Brazil. Despite 30 years having passed since its isolation, little is known about the neuropathology induced by the Maraba virus. Accordingly, in this study the histopathological features, inflammatory glial changes, cytokine concentrations, and nitric oxide activity in the encephalon of adult mice subjected to Maraba virus nostril infection were evaluated. The results showed that 6 days after intranasal inoculation, severe neuropathological-associated disease signs appeared, including edema, necrosis and pyknosis of neurons, generalized congestion of encephalic vessels, and intra- and perivascular meningeal lymphocytic infiltrates in several brain regions. Immunolabeling of viral antigens was observed in almost all central nervous system (CNS) areas and this was associated with intense microglial activation and astrogliosis. Compared to control animals, infected mice showed significant increases in interleukin (IL)-6, tumor necrosis factor (TNF)-α, interferon (INF)-γ, MCP-1, nitric oxide, and encephalic cytokine levels. We suggest that an exacerbated inflammatory response in several regions of the CNS of adult BALB/c mice might be responsible for their deaths.

Localization of NADPH diaphorase activity in the human visual cortex

The present report describes the activity of NADPH-diaphorase (NADPHd) in area 17 of autopsied normal human visual cortex. Four human brains from autopsy tissue (4-8 h postmortem) were fixed by immersion in 4 per cent paraformaldehyde in 0.1 M sodium phosphate buffer, pH 7.2-7.4, or in 10 per cent formalin for 24 h. NADPHd histochemistry was done using the malic enzyme indirect method. The neurpile pattern of enzyme activity presented a clear six layer appearance. Cell morphology and the laminar distribution of 73 NADPHd-positive neurons are descrived. All neurons found in area 17 of human cortex were sparsely spiny or smooth cells, located in all cortical layers exept layer 4c. Quantitative analysis of the branching pattern of the dendritic tree was carried out. A symmetrical pattern was observed with no particular dendritic bias except for a few white matter and layer 1 cells. Larger dendritic fields were found in white matter cells when compared to the other corical layers. Comparison of cell densities for gray and white matters showed that 85 per cent of the NADPHd-positive neurons were located in the white matter. NADPH was colocalized with nitric oxide synthase which produces nitric oxide, a short-life neuromediator implicated in synaptic plasticity, neuroprotection, and neurotoxicity. thus, the spatial distribution of the NADPHd cells is important for posterior functional studies of the neuromediators in the brain

The visual cortex of the agouti (Dasyprocta agouti): architectonic subdivisions

1. We have studied the cytoarchitecture and myeloarchitecture of the agouti's cortical surface that can be activated by visual stimulation. Five architectonic subdivisions that correspond to distinctive visuotopic representations were characterized. 2. The largest portion of the visual cortex is occupied by area 17 which is situated lateral to the cingulate cortex, medial to area 18, posterior to the parietal cortex, and anterior to the agranular retrosplenial cortex. Additionally, four architectonic subdivisions in the extrastriate visual cortex were distingished, i. e., from medial to lateral: area 18, area 19, anterior lateral area, and temporal posterior area. 3. Along the border of the extrastriate cortex a ring of nonvisual cortical fiels was encountered encompassing parietal (somatic sensorial) cortex, temporal anterior and temporal intermediate (auditory) areas, a band of pre-rhinal cortex, and agranular retrosplenial cortex