الملخص
After a traumatic injury to the central nervous system, the distal stumps of axons undergo Wallerian degeneration (WD), an event that comprises cytoskeleton and myelin breakdown, astrocytic gliosis, and overexpression of proteins that inhibit axonal regrowth. By contrast, injured neuronal cell bodies show features characteristic of attempts to initiate the regenerative process of elongating their axons. The main molecular event that leads to WD is an increase in the intracellular calcium concentration, which activates calpains, calcium-dependent proteases that degrade cytoskeleton proteins. The aim of our study was to investigate whether preventing axonal degeneration would impact the survival of retinal ganglion cells (RGCs) after crushing the optic nerve. We observed that male Wistar rats (weighing 200-400 g; n=18) treated with an exogenous calpain inhibitor (20 mM) administered via direct application of the inhibitor embedded within the copolymer resin Evlax immediately following optic nerve crush showed a delay in the onset of WD. This delayed onset was characterized by a decrease in the number of degenerated fibers (P<0.05) and an increase in the number of preserved fibers (P<0.05) 4 days after injury. Additionally, most preserved fibers showed a normal G-ratio. These results indicated that calpain inhibition prevented the degeneration of optic nerve fibers, rescuing axons from the process of axonal degeneration. However, analysis of retinal ganglion cell survival demonstrated no difference between the calpain inhibitor- and vehicle-treated groups, suggesting that although the calpain inhibitor prevented axonal degeneration, it had no effect on RGC survival after optic nerve damage.
الموضوعات
Animals , Male , Polyvinyls/pharmacology , Retinal Ganglion Cells/drug effects , Axons/drug effects , Wallerian Degeneration/drug therapy , Glycoproteins/pharmacology , Optic Nerve Injuries/drug therapy , Axons/pathology , Immunohistochemistry , Cell Survival/drug effects , Treatment Outcome , Cell Death/drug effects , Cell Death/physiology , Rats, Wistar , Optic Nerve Injuries/pathology , Microscopy, Electron, Transmission , Nerve Crushالملخص
Os autores estudaram os componentes do microplancton em habitat de Biomphalaria glabrata (Say 1818), observando a nutricao e o crescimento dos planorbideos em situacoes de aumento e diminuicao da microflora e microfauna. Algumas especies de microalgas (Diatomaceas) foram encontradas no trato digestivo de B. glabrata, servindo-lhe de alimento. Atencao foi dispensada aos componentes da microflora e microfauna com apresentacao do quadro quantitativo, sistematica e ecologia das especies de Bacillariophyceae, Chorophyceae, Cyanophyceae, Euglenophyceae encontradas nas diversas amostras. As mais frequentes foram Nitzschia, Navicula, Pinnularia, Comphonema, Eunotia, Synedra, Hanitzchia, Cymbella A biometria dos planorbideos capturados nos varios meses de coleta mostra a ocorrencia de caramujos adultos e jovens, com riesgo do percentual de exemplares positivos para a liberacao de cercaria. Referencia tambem foi feita a biologia de Pistia stratiotes Linneu, entre outras plantas aquaticas que faziam parte da biocenose do charco situado na cidade de Castro Alves, Bahia