Rescuing axons from degeneration does not affect retinal ganglion cell death

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.

MDGC-MS analysis of essential oils from Protium heptaphyllum (Aubl. ) and their antifungal activity against Candida specie / Análise MDGC-MS de óleos essenciais de Protium heptaphyllum (Aubl. ) e sua atividade antifúngica contra espécies de Candida

ABSTRACT Protium heptaphyllum is found in the Amazon region, and in various Brazilian states and South American countries. Also Known as almecega, it produces an oil resin used in traditional medicine as analgesic, anti-inflammatory, cicatrizant and expectorant, it is rich in pentacyclic triterpenes and essential oil. The main objective of this study was to analyze the chemical composition of P. heptaphyllumresin (OEPh) over different extraction times and to evaluate their antifungal activity against Candida species, obtained from gardeners with onychomycosis, using the disk diffusion method. The OEPh was obtained by hydrodistillation and analyzed by Multidimensional Gas Chromatography coupled with Mass Spectrometry (MDGC / MS). Candida species were obtained from lesions on the nails of horticulturist from a community garden in the city of Teresina, Piauí, Brazil. The antifungal activity in concentrations of 1000 µg/L, 500 µg/L and 250 µg/L, PROTOCOL M44-A2 (CLSI 2009) OEPh was tested. The main constituents identified were: l-limonene, α-terpineol, p-cineol, o-cymene and α-phellandrene, however, its composition varies significantly with extraction time. All species, except C. rugosa, were inhibited with halo (≥ 14 mm) at 1000 μg / L. C. krusei is naturally resistant to the drug fluconazole, but when tested with OEPh the clinical species (case 9) demonstrated sensitivity in three dilutions (halo ≤ 10 ≥ 14) and the standard strain was inhibited at concentration of 1000 μg/Lg / L (halo 14mm). A similar situation also occurred with the standard strain of C. parapsilosis (halo ≥ 11mm). OEPh has considerable antifungal activity, which merits further investigation for alternative clinical applications, since this species is widely distributed in our community, and it presents good yields, and also has important therapeutic applications.

RESUMO Protium heptaphyllum é encontrada na região amazônica, em vários estados do Brasil e países da América do Sul. Conhecida como almecega produz uma resina oleosa usada na medicina popular como analgésica, antiinflamatória, cicatrizante e expectorante, é rica em triterpenos pentaciclicos e óleo essencial. O objetivo principal do presente trabalho foi analisar a composição química do óleo essencial da resina P. heptaphyllum (OEPh) em diferentes tempo de extração e avaliarsuaatividade antifúngica contra espécies de Candida, isoladas de horticultores com onicomicoses, por método de disco-difusão. O OEPh foi obtido por hidrodestilação, analisado por Cromatografia Gasosa Multidimensinal Acoplada a Espectrometria de Massas (MDGC/MS). As espécies de Candida foram obtidas de lesões nas unhas de horticultores de uma horta comunitária na cidade de Teresina, Piauí, Brasil. Testou-se a atividade antifúngica do OEPhnas concentrações de 1000 μg/L, 500 μg/L e 250 μg/L, protocolo M44-A2 (CLSI 2009). Os principais constituintes identificados foram l- limoneno, α-terpineol, p-cineol, o-cimeno e α-felandreno, entretanto, sua composição varia significativamente em decorrência do tempo de extração. Todas as espécies, exceto a C. rugosa, foram inibidas com halo ( Χ ≥ 14 mm) na concentração de 1000 μg/L. C. krusei é naturalmente resistente ao fármaco fluconazol, mas quando testado com OEPh,a espécie clínico (caso 9) demonstrou sensibilidade nas três diluições (halo Χ ≤ 10 ≥ 14) e a cepa padrão foi inibida na concentração de 1000 μg/L (halo Χ 14mm). Fato semelhante também ocorreu com a cepa padrão de C. parapsilosis (halo Χ ≥ 11mm). O OEPh possui atividade antifúngica considerável, merecendo uma investigação mais aprofundada para aplicações clínicas alternativas, uma vez que esta espécie é amplamente distribuída em nossa comunidade, apresenta bom rendimento e, ainda, aplicações terapêuticas importantes.

Losses of immunoreactive parvalbumin amacrine and immunoreactive alphaprotein kinase C bipolar cells caused by methylmercury chloride intoxication in the retina of the tropical fish Hoplias malabaricus

To quantify the effects of methylmercury (MeHg) on amacrine and on ON-bipolar cells in the retina, experiments were performed in MeHg-exposed groups of adult trahiras (Hoplias malabaricus) at two dose levels (2 and 6 µg/g, ip). The retinas of test and control groups were processed by mouse anti-parvalbumin and rabbit anti-alphaprotein kinase C (alphaPKC) immunocytochemistry. Morphology and soma location in the inner nuclear layer were used to identify immunoreactive parvalbumin (PV-IR) and alphaPKC (alphaPKC-IR) in wholemount preparations. Cell density, topography and isodensity maps were estimated using confocal images. PV-IR was detected in amacrine cells in the inner nuclear layer and in displaced amacrine cells from the ganglion cell layer, and alphaPKC-IR was detected in ON-bipolar cells. The MeHg-treated group (6 µg/g) showed significant reduction of the ON-bipolar alphaPKC-IR cell density (mean density = 1306 ± 393 cells/mm²) compared to control (1886 ± 892 cells/mm²; P < 0.001). The mean densities found for amacrine PV-IR cells in MeHg-treated retinas were 1040 ± 56 cells/mm² (2 µg/g) and 845 ± 82 cells/mm² (6 µg/g), also lower than control (1312 ± 31 cells/mm²; P < 0.05), differently from the data observed in displaced PV-IR amacrine cells. These results show that MeHg changed the PV-IR amacrine cell density in a dose-dependent way, and reduced the density of alphaKC-IR bipolar cells at the dose of 6 µg/g. Further studies are needed to identify the physiological impact of these findings on visual function.