Extracellular tetraethylammonium (TEA+) inhibits the current carried out by K+ ions in potassium channels. Structural models of wild-type (WT) and Y82C KcsA K+ channel/TEA+ complexes are here built using docking procedures, electrostatics calculations and molecular dynamics simulations. The calculations are based on the structure determined by Doyle et al. (11) Our calculations suggest that in WT, the TEA+ cation turns binds at the outer mouth of the selectivity filter, stabilized by electrostatic and hydrophobic interactions with the four Tyr82 side chains. Replacement of Tyr82 with Cys causes a decrease of the affinity of the cation for the channel, consistently with the available site-directed mutagenesis data (16). An MD simulation in which K+ replaces TEA+ provides evidence that TEA+ binding site can accommodate a potassium ion, in agreement with the high-resolution structure recently reported by Zhou et al. (20)
ADAM10 is a multi-functional proteinase that can cleave approximately 100 different substrates. Previously, it was demonstrated that ADAM10 is expressed by ameloblasts, which are required for enamel formation. The goal of this study was to determine if ADAM10 is necessary for enamel development.
While there is ample evidence for the efficacy of IPT, confirmed through the results of the efficacy review, on the ground implementation factors are less well understood. We compiled a book on the global reach of IPT by requesting contributions from local authors through word-of-mouth methods. This approach resulted in reports from 31 countries across six continents and 15 diverse populations within the US that spanned the age range and types of usage.
Laboratório de Microbiologia e Controle de Alimentos, Instituto de Ciência e Tecnologia de Alimentos, Universidade Federal do Rio Grande do Sul (ICTA/UFRGS), Av. Bento Gonçalves 9.500, prédio 43212, Campus do Vale, Agronomia, Porto Alegre, RS, CEP: 91501-970, Brazil.
Handlers can wear masks during food preparation to avoid contamination of the nose and mouth. However, if microorganisms can pass through mask layers and handlers touch their outer surfaces, their hands can contaminate the food being handled. This study evaluated the behavior of 31 food handlers wearing disposable masks in a food service kitchen.
The tusk of the male narwhal is a prolonged canine tooth, reaching a size of up to 3 m in length. The tusk erupts through the young narwhal's upper left lip and, over time, develops into an elongated structure composed of dentine growth layers with an outer coating of cementum. In this study, we utilized bomb radiocarbon (C) to estimate the ages of three narwhal tusks, which allowed us to validate the assumption that one growth layer is deposited annually in narwhal tusks.
