3 research outputs found
Inhibition of alpha-synuclein fibrillization by dopamine is mediated by interactions with five C-terminal residues and with E83 in the NAC region
The interplay between dopamine and alpha-synuclein (AS) plays a central role in Parkinson's disease (PD). PD results primarily from a severe and selective devastation of dopaminergic neurons in substantia nigra pars compacta. The neuropathological hallmark of the disease is the presence of intraneuronal proteinaceous inclusions known as Lewy bodies within the surviving neurons, enriched in filamentous AS. In vitro, dopamine inhibits AS fibril formation, but the molecular determinants of this inhibition remain obscure. Here we use molecular dynamic (MD) simulations to investigate the binding of dopamine and several of its derivatives onto conformers representative of an NMR ensemble of AS structures in aqueous solution. Within the limitations inherent to MD simulations of unstructured proteins, our calculations suggest that the ligands bind to the (125)YEMPS(129) region, consistent with experimental findings. The ligands are further stabilized by long-range electrostatic interactions with glutamate 83 (E83) in the NAC region. These results suggest that by forming these interactions with AS, dopamine may affect AS aggregation and fibrillization properties. To test this hypothesis, we investigated in vitro the effects of dopamine on the aggregation of mutants designed to alter or abolish these interactions. We found that point mutations in the (125)YEMPS(129) region do not affect AS aggregation, which is consistent with the fact that dopamine interacts non-specifically with this region. In contrast, and consistent with our modeling studies, the replacement of glutamate by alanine at position 83 (E83A) abolishes the ability of dopamine to inhibit AS fibrillization
Sensibilidade e resistĂȘncia de amostras de Salmonella Typhimurium isoladas de suĂnos abatidos no Rio Grande do Sul/Brasil frente aos desinfetantes quĂmicos quaternĂĄrio de amĂŽnio e iodofor Sensitivity and resistance of samples of Salmonella Typhimurium isolated in slaughter swines in the state Rio Grande do Sul/Brazil, front to disinfectants quaternary ammonium and iodophor
Na prevenção da ocorrĂȘncia ou na interrupção da evolução de enfermidades infecto-transmissĂveis comuns aos animais e aos seres humanos, como Ă© o caso da salmonelose, o uso de um desinfetante capaz de agir sobre o agente causal quando em vida livre, no ambiente, exerce grande importĂąncia. No entanto, a resistĂȘncia microbiana, intrĂnseca ou adquirida, pode apresentar-se como um limitante no uso deste instrumento sanitĂĄrio. Objetivando monitorar a sensibilidade da Salmonella Typhimurium, 96 amostras isoladas de suĂnos abatidos no Estado do Rio Grande do Sul,Brasil, foram confrontadas com dois compostos quĂmicos desinfetantes (origem comercial) de uso freqĂŒente em ambientes de produção animal e de transformação de seus subprodutos: um quaternĂĄrio de amĂŽnio e o iodofor. Foram usadas as concentraçÔes indicadas pelo fabricante e uma menor para simular possĂvel situação de sub-concentração. O mĂ©todo de verificação foi o de diluição atravĂ©s do teste de suspensĂŁo, observando a inativação bacteriana nos tempos de contato 5, 15, 30 e 60 minutos. Como resultados obtidos, todas as amostras foram inativadas quando utilizado o composto quaternĂĄrio de amĂŽnio, em ambas as concentraçÔes. Frente ao iodofor, 4 (quatro) amostras mostraram-se resistentes a este composto na concentração indicada e 59 frente Ă sub-concentração. Conclui-se ser necessĂĄrio, seja para a eleição ou para o monitoramento da eficĂĄcia, o confronto dos desinfetantes/anti-sĂ©pticos com bactĂ©rias presentes nos ambientes especĂficos de produção animal ou mesmo nos de transformação de seus subprodutos.<br>For prevention of infectious diseases common to man and animals such as salmonellosis, the successful use of disinfectants is of great importance. However, intrinsic or acquired resistance presented by microorganism against these compounds may constitute a limiting aspect in disinfections protocols. This study was aimed at monitoring the sensitivity of 96 Salmonella Typhimurium strains isolated from slaughter pigs in the state of Rio Grande do Sul, Brazil. The isolates were tested against quaternary ammonium and iodophor, which represent two commercial disinfectants commonly used in animal production. The tested disinfectants were used in the concentration recommended by the fabricant and in a sub-concentration in order to simulate a possible field situation. Dilution suspension tests were conducted, observing the inactivation of each S.Typhimurium isolate after 5, 15, 30 and 60 minutes of contact with each compound. All tested isolates were inactivated by the quaternary ammonium compound in both concentrations. Four isolates revealed resistant to iodophor in the recommended concentration and 59 isolates when a sub-concentration was tested. The testing of resistance against disinfectants in microorganisms present on farm and in food processing plants might be an important step on monitoring the effectiveness of adopted disinfections protocols