Selenium (IV,VI) reduction and tolerance by fungi in an oxic environment.

Microbial processes are known to mediate selenium (Se) oxidation-reduction reactions, strongly influencing Se speciation, bioavailability, and transport throughout the environment. While these processes have commonly been studied in anaerobic bacteria, the role that aerobic fungi play in Se redox reactions could be important for Se-rich soil systems, dominated by microbial activity. We quantified fungal growth, aerobic Se(IV, VI) reduction, and Se immobilization and volatilization in the presence of six, metal-tolerant Ascomycete fungi. We found that the removal of dissolved Se was dependent on the fungal species, Se form (i.e., selenite or selenate), and Se concentration. All six species grew and removed dissolved Se(IV) or Se(VI) from solution, with five species reducing both oxyanions to Se(0) biominerals, and all six species removing at least 15%-20% of the supplied Se via volatilization. Growth rates of all fungi, however, decreased with increasing Se(IV,VI) concentrations. All fungi removed 85%-93% of the dissolved Se(IV) within 10 d in the presence of 0.01 mm Se(IV), although only about 20%-30% Se(VI) was removed when grown with 0.01 mm Se(VI). Fungi-produced biominerals were typically 50- to 300-nm-diameter amorphous or paracrystalline spherical Se(0) nanoparticles. Our results demonstrate that activity of common soil fungi can influence Se form and distribution, and these organisms may therefore play a role in detoxifying Se-polluted environments.

Morphology, structure, and metal binding mechanisms of biogenic manganese oxides in a superfund site treatment system.

Manganese oxides, which may be biogenically produced in both pristine and contaminated environments, have a large affinity for many trace metals. In this study, water and Mn oxide-bearing biofilm samples were collected from the components of a pump and treat remediation system at a superfund site. To better understand the factors leading to their formation and their effects on potentially toxic metal fate, we conducted a chemical, microscopic, and spectroscopic characterization of these biofilm samples. Scanning electron microscopy revealed the presence of Mn oxides in close association with biological structures with morphologies consistent with fungi. X-ray absorption spectroscopy (XAS) and X-ray diffraction (XRD) revealed the oxides to be a mixture of layer and tunnel structure Mn(iv) oxides. In addition, XAS suggested that Ba, Co, and Zn all primarily bind to oxides in the biofilm in a manner that is analogous to synthetic or laboratory grown bacteriogenic Mn oxides. The results indicate that Mn oxides produced by organisms in the system may effectively scavenge metals, thus highlighting the potential utility of these organisms in designed remediation systems.

Luxo-fractura de monteggia: a propósito de un caso / The monteggia lession: a purpuse of the case clinic

La fractura de Monteggia es muy rara y comprende solo el 2 por ciento de las fracturas que afectan el codo en niños, con una incidencia por edades que va desde 7 a 10 años, pero puede aparecer en lactantes y adolescentes. Su rareza ha despertado enorme interés por las complicaciones graves que conlleva su tratamiento inadecuado, o cuando en el peor de los casos no se le diagnostica. Presentamos un escolar femenino de 10 años de edad quien posterior a caida desde sus propios pies con el codo en hiperextensión presentó deformidad e impotencia funcional del codo izquierdo. En estudios radiológicos diagnostica luxo-fractura de Monteggia tipo I, realizando cerrada y colocación de yeso braquipalmar en supinación evolucionando satisfactoriamente