Anodic stripping voltammetry of arsenic determination with edible mushroom-nafion-modified glassy carbon electrode.

An edible Mushroom-Nafion modified glassy carbon electrode (M2N5-GCE) was prepared using a homogeneous mixture varying the concentrations of these, in addition to the origin of the mushroom (Shiitake, Lentinula edodes, M1 and Abrantes, Agariscus bisporus, M2) and applied to the As(III) determination by anodic stripping voltammetry. After choosing the optimal conditions in the preparation of the electrode, the second stage was to study the effects of various parameters such as supporting electrolyte, pH, accumulation potential, and time (Eacc, tacc). The optimum experimental conditions chosen were Britton Robinson buffer 0.01 mol L-1 pH:4.6; Eacc: -1.0 and tacc: 60 s obtaining a signal of oxidation of As(0) to As(III) about 0.08 V. Peak current was proportional to arsenic concentration over the 19.6-117.6 µg L-1 range, with a 3σ detection limit of 13.4 µg L-1. The method was validated using As(III) spiked tap water from the laboratory with satisfactory results (RE:3.0 %). Finally, the method was applied to the determination of As(III) in water samples from the Loa River (Northern Chile) in the presence of As(V) in a concentration >20 times higher (RE: 2.3 %).

Polymyositis: A Case Report.

Inflammatory myopathies are a group of diseases whose common pathway is immune-mediated muscle damage, one of which is polymyositis. The definition of polymyositis is controversial, with proponents advocating a definition based on immunohistochemical and histopathological findings in muscle biopsies, while other proponents advocate a definition based on clinical manifestations and histopathological findings. Polymyositis is a quite rare disease that is clinically characterized by progressive proximal muscle weakness with a symmetric distribution. Within the diagnostic approach, laboratory studies show elevation of sarcoplasmic enzymes; nerve conduction tests are performed, which may aid in distinguishing myopathic causes of weakness from neuropathic disorders; and muscle biopsy is considered the gold standard to diagnose inflammatory myopathy and to distinguish the subclasses. We report the case of a 61-year-old male patient who presented generalized symmetrical weakness, predominantly in the upper extremities, and dysphagia, whose laboratory studies, autoantibodies, and muscle biopsy were confirmatory of this entity.

Single-molecule imaging with cell-derived nanovesicles reveals early binding dynamics at a cyclic nucleotide-gated ion channel.

Ligand binding to membrane proteins is critical for many biological signaling processes. However, individual binding events are rarely directly observed, and their asynchronous dynamics are occluded in ensemble-averaged measures. For membrane proteins, single-molecule approaches that resolve these dynamics are challenged by dysfunction in non-native lipid environments, lack of access to intracellular sites, and costly sample preparation. Here, we introduce an approach combining cell-derived nanovesicles, microfluidics, and single-molecule fluorescence colocalization microscopy to track individual binding events at a cyclic nucleotide-gated TAX-4 ion channel critical for sensory transduction. Our observations reveal dynamics of both nucleotide binding and a subsequent conformational change likely preceding pore opening. Kinetic modeling suggests that binding of the second ligand is either independent of the first ligand or exhibits up to ~10-fold positive binding cooperativity. This approach is broadly applicable to studies of binding dynamics for proteins with extracellular or intracellular domains in native cell membrane.

Management of a Damaged Implant for Retention of an Overdenture Prosthesis and Fixed Single Crown: Clinical Reports.

This article demonstrates a method to salvage an implant that has been damaged or is no longer usable because of a fractured screw that cannot be removed. In the first situation the patient had a Locator abutment that fractured during torqueing of the abutment. Despite the attempt to remove the fractured screw, it was not retrievable, and the internal threads of the implant were damaged in the attempt to remove the screw. Rather than removing the implant or covering it and sleeping the implant, a custom cast post was used to restore the implant to function. A second example describes a patient with a fixed implant crown. The implant was damaged during attempts to remove the fractured screw. A custom post was fabricated and cemented, and a new crown was fabricated.

Recuento espermático, peso corporal y pesos de órganos reproductivos pos hipoxia hipobárica intermitente simuladan en ratón (mus musculus) / Sperm count, body and reproductive organs weight post simulated intermittent hypobaric hypoxia on mouse (mus musculus)

En ratones sometidos a hipoxia hipobárica intermitente (HI) producto de una exposición simulada a la altura, en cámara hipobárica (asemejándose a condiciones laborales de faena minera del norte de Chile), se evaluó recuento espermático total y cambios en el peso corporal y de órganos reproductivos.El grupo experimental se sometió a HI y el control permaneció en normoxia,ambos durante 108 días. No existieron cambios estadísticamente significativos (p > 0,05) en los pesos pos HI, posiblemente por pequeñas compensaciones durante el periodo de normoxia normobárica o los intervalos de hipoxia hipobárica no fueron lo suficientemente prolongados como para generar cambios. No hubo cambios en el recuento espermático testicular, pero sí en cauda epididimaria, donde el grupo control fue estadísticamente superior,debido posiblemente a enlentecimiento del tránsito entre el testículo y la cauda epididimaria o que ésta no está cumpliendo su función de almacenamiento (tránsito acelerado y depleción de la vía seminal). Por tanto, resulta imprescindible profundizar el estudio de la HI y su repercusión en la reproducción, ya que esta situación afectaría a trabajadores de las faenas mineras en Chile.

Total sperm count and changes in body and reproductive organs weight were evaluated in mice subjected to intermittent hypobaric hypoxia (IHH) product of a simulated exposure to high altitudes, in hypobaric chamber (in a similar situation to that of working conditions of mining activities in the north of Chile). The experimental group was exposed to IHH and the control group maintained in conditions of normoxia, both for 108 days. There were no statistically significant changes (p>0,05) in weights post IHH, possibly because of small compensations during the normobaric normoxia period or the alternant exposure to a hypoxic environment was not sufficient for changes to develop. No changes in testicular sperm count were noted but in epididymal cauda, where control group was statistically higher due to a possible slowness of transit between testicle and epididymal cauda or because the spermstorage function of epididymis is not adequate (accelerated transit and seminal vesicle depletion). Therefore, it is essential to study in depth the IHH and its impact on reproduction, because this situation may affect Chilean mining workers.