The study of metal-tolerant bacteria is important for bioremediation of contaminated environments and development of green technologies for material synthesis due to their potential to transform toxic metal ions into less toxic compounds by mechanisms such as reduction, oxidation and/or sequestration. In this study, we report the isolation of seven lead-tolerant bacteria from a metal-contaminated site at Zacatecas, México. The bacteria were identified as members of the Staphylococcus and Bacillus genera by microscopic, biochemical and 16S rDNA analyses. Minimal inhibitory concentration of these isolates was established between 4.5 and 7.0 mM of Pb(NO) in solid and 1.0-4.0 mM of Pb(NO) in liquid media. A quantitative analysis of the lead associated to bacterial biomass in growing cultures, revealed that the percentage of lead associated to biomass was between 1 and 37% in the PbT isolates. A mechanism of complexation/biosorption of lead ions as inorganic phosphates (lead hydroxyapatite and pyromorphite) in bacterial biomass, was determined by Fourier transform infrared spectroscopy and X-ray diffraction analyses. Thus, the ability of the lead-tolerant isolates to transform lead ions into stable and highly insoluble lead minerals make them potentially useful for immobilization of lead in mining waste.

A total of sixteen composite soil and sediment samples were collected during the rainy and dry season in Asientos, Aguascalientes, Mexico, an area recently affected by increased mining operations. Physicochemical characterization showed that substrates were moderately to strongly calcareous with predominantly neutral to slightly alkaline pH, moderate to high cation-exchange capacity and high organic matter content. Due to these conditions, Cd, Pb, Cu and Zn were not water leachable despite high concentrations; up to 105.3, 7052.8, 414.7 and 12,263.2 mg kg(-1) respectively. However, Cd and Pb were considered to be easily mobilizable as they were found predominantly associated with exchangeable and carbonate fractions, whereas Cu and Zn were found associated with Fe/Mn oxide and organic matter fractions. The results highlighted the influence of physicochemical substrate properties on the mobility of metals and its importance during the evaluation of the potential current and future risk metal contamination presents in affected areas.

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Los opioides desde hace muchos años son los analgésicos más utilizados y efectivos para el tratamiento del dolor. Este trabajo da a conocer la clasificación farmacológica, usos terapéuticos, riesgos a la salud y reacciones adversas de los opioides como fármacos, planteando el paradigma del usar este tipo de fármacos para el control del dolor, sin embargo se han convertido en un problema de salud en distintos países ya que en ciertas circunstancias tienen un alto potencial de causar adicción. Además de su uso contra el dolor, los opioides son utilizados como antidiarreicos, antitusivos y para el tratamiento de diversas sintomatologías. A pesar de los efectos adversos, el mal uso y abuso de los opioides; se consideran imprescindibles en la terapia contra el dolor. Actualmente las investigaciones farmacéuticas trabajan en la búsqueda constante de nuevos fármacos con efectos menos severos y con potencia analgésica