In vivo antimicrobial activity of silver nanoparticles produced via a green chemistry synthesis using Acacia rigidula as a reducing and capping agent

Introduction: One of the main issues in the medical field and clinical practice is the development of novel and effective treatments against infections caused by antibiotic-resistant bacteria. One avenue that has been approached to develop effective antimicrobials is the use of silver nanoparticles (Ag-NPs), since they have been found to exhibit an efficient and wide spectrum of antimicrobial properties. Among the main drawbacks of using Ag-NPs are their potential cytotoxicity against eukaryotic cells and the latent environmental toxicity of their synthesis methods. Therefore, diverse green synthesis methods, which involve the use of environmentally friendly plant extracts as reductive and capping agents, have become attractive to synthesize Ag-NPs that exhibit antimicrobial effects against resistant bacteria at concentrations below toxicity thresholds for eukaryotic cells. Purpose: In this study, we report a green one-pot synthesis method that uses Acacia rigidula extract as a reducing and capping agent, to produce Ag-NPs with applications as therapeutic agents to treat infections in vivo. Materials and methods: The Ag-NPs were characterized using transmission electron microscopy (TEM), high-resolution TEM, selected area electron diffraction, energy-dispersive spectroscopy, ultraviolet–visible, and Fourier transform infrared. Results: We show that Ag-NPs are spherical with a narrow size distribution. The Ag-NPs show antimicrobial activities in vitro against Gram-negative (Escherichia coli, Pseudomonas aeruginosa, and a clinical multidrug-resistant strain of P. aeruginosa) and Gram-positive (Bacillus subtilis) bacteria. Moreover, antimicrobial effects of the Ag-NPs, against a resistant P. aeruginosa clinical strain, were tested in a murine skin infection model. The results demonstrate that the Ag-NPs reported in this work are capable of eradicating pathogenic resistant bacteria in an infection in vivo. In addition, skin, liver, and kidney damage profiles were monitored in the murine infection model, and the results demonstrate that Ag-NPs can be used safely as therapeutic agents in animal models. Conclusion: Together, these results suggest the potential use of Ag-NPs, synthesized by green chemistry methods, as therapeutic agents against infections caused by resistant and nonresistant strains. Keywords: silver nanoparticles, green synthesis, in vitro antibacterial activity, in vivo antibacterial activity, skin infection, toxicological stud

La privación selectiva de sueño de movimientos oculares rápidos (MOR) durante 24 h no modifica la inmunoreactividad de c-Fos en la Columna Respiratoria Ventral (VRC) de rata

La generación y modulación de la respiración es controlada por la columna respiratoria ventral (VRC), la cual incluye: el grupo respiratorio parafacial/núcleo retrotrapezoide (pFRG/RTN), el complejo Bötzinger (BötC) y el complejo preBötzinger (preBötC). Una correlación entre el sueño y la respiración es particularmente clara en condiciones como la apnea obstructiva del sueño y el síndrome de hipoventilación central congénita. En este trabajo, mediante la inmunoreactividad contra c-Fos como un marcador indirecto de la actividad neuronal, se estudió el efecto de la privación selectiva de sueño MOR a corto plazo sobre la actividad de las neuronas en la VRC. Ratas macho Wistar fueron divididas en dos grupos: control (n=6) y 24 h de privación selectiva de sueño MOR utilizando la técnica de florero invertido (n=11). La frecuencia respiratoria, la frecuencia cardíaca, la temperatura y la saturación de oxígeno (SpO2) se midieron antes y durante la privación de sueño MOR. El grupo de privación de sueño MOR no mostró diferencias estadísticamente significativas con respecto al grupo control. Sin embargo, la frecuencia cardíaca del grupo de privación de sueño MOR aumentó y la SpO2 disminuyó significativamente en comparación con los valores basales. Estos datos sugieren que, en ausencia de sueño MOR, la actividad de las neuronas respiratorias en la VRC está altamente regulada para asegurar la homeostasis de gases y una tasa de respiración estable y que los cambios fisiológicos encontrados probablemente están regulados por núcleos no relacionados con la generación del ritmo respiratori