Browsing by Author "Sandoval, Rodrigo"

Now showing 1 - 2 of 2
  • No Thumbnail Available
    Item
    A Novel Earwax Self-Sampling Device: A Feasibility Study
    (2021) Herane-Vives, Andres; Sandoval, Rodrigo; Ortega, Lorena; Espinoza, Susana; Cleare, Anthony; Hayes, Alexander; Ortuzar, Esteban; Valdenegro, Tomas; Aguilo, Bruno; Benoehr, Jan; Arnone, Danilo
    (1) Background: Earwax might provide the long-term concentration of substances that are altered in chronic diseases. Standardised earwax extraction has to be exclusively performed by clinicians. We investigated the safety, reliability, and tolerance of a novel self-sampling earwax device in comparison with a clinical method; (2) Methods: We compared the reliability between both methods in a longitudinal study. We first cleaned both ears at baseline in 37 controls. Secondly, we obtained a sample a month after by extracting earwax from the right ear with a novel self-sampling device, and from the left ear by using the clinical method. Reliability of both methods was measured by coefficients of variation; (3) Results: The weight of the baseline samples was not significantly different between ear sides. The reliability of the two methods was not significantly different. The self-extraction method removed eight times more earwax than the clinical method. The new method proved to be well tolerated; (4) Conclusions: The novel device was as reliable as the clinical method in sampling earwax. In view of its practicality, safety, tolerability and efficiency, the new method may have clinical applications at a reduced cost.
  • No Thumbnail Available
    Item
    Antagonistic effects of TrkB and p75NTR on NMDA receptor currents in post-synaptic densities transplanted into Xenopus oocytes
    (2007) Sandoval, Mauricio; Sandoval, Rodrigo; Thomas, Ulrich; Spilker, Christina; Smalla, Karl-Heinz; Falcon, Romina; Marengo, Juan Jose; Calderon, Rodrigo; Saavedra, Veronica; Heumann, Rolf; Bronfman, Francisca; Garner, Craig C.; Gundelfinger, Eckart D.; Wyneken, Ursula
    Brain-derived neurotrophic factor (BDNF) and its receptor TrkB are essential regulators of synaptic function in the adult CNS. A TrkB-mediated effect at excitatory synapses is enhancement of NMDA receptor (NMDA-R)-mediated currents. Recently, opposing effects of TrkB and the pan-neurotrophin receptor p75(NTR) on long-term synaptic depression and long-term potentiation have been reported in the hippocampus. To further study the regulation of NMDA-Rs by neurotrophin receptors in their native protein environment, we micro-transplanted rat forebrain post-synaptic densities (PSDs) into Xenopus oocytes. One-minute incubations of oocytes with BDNF led to dual effects on NMDA-R currents: either TrkB-dependent potentiation or TrkB-independent inhibition were observed. Pro-nerve growth factor, a ligand for p75(NTR) but not for TrkB, produced a reversible, dose-dependent, TrkB-independent and p75(NTR)-dependent inhibition of NMDA-Rs. Fractionation experiments showed that p75(NTR) is highly enriched in the PSD protein fraction. Immunoprecipitation and pull-down experiments further revealed that p75(NTR) is a core component of the PSD, where it interacts with the PDZ3 domain of the scaffolding protein SAP90/PSD-95. Our data provide striking evidence for a rapid inhibitory effect of p75(NTR) on NMDA-R currents that antagonizes TrkB-mediated NMDA-R potentiation. These opposing mechanisms might be present in a large proportion of forebrain synapses and may contribute importantly to synaptic plasticity.