ABSTRACT
INTRODUCTION: The indirect bonding technique optimizes fixed appliance installation at the orthodontic office, ensuring precise bracket positioning, among other advantages. In this laboratory clinical phase, material and methods employed in creating the transfer tray are decisive to accuracy. OBJECTIVE: This article describes a simple, efficient and reproducible indirect bonding technique that allows the procedure to be carried out successfully. Variables influencing the orthodontic bonding are analyzed and discussed in order to aid professionals wishing to adopt the indirect bonding technique routinely in their clinical practice. .
INTRODUÇÃO: a técnica de colagem indireta prioriza a otimização do procedimento de montagem do aparelho fixo na clínica ortodôntica, assegurando, entre outras, vantagens relacionadas à precisão no posicionamento dos braquetes. Nesse procedimento clínico laboratorial, o material e o método de confecção da moldeira de transferência são determinantes no quesito precisão. OBJETIVO: este artigo descreve uma técnica de colagem indireta simples, eficiente e reprodutível, para que o procedimento possa ser realizado com sucesso. Variáveis que exercem influência sobre o procedimento são analisadas e discutidas, a fim de auxiliar o profissional a adotar, de forma rotineira, a técnica de colagem indireta em sua prática clínica. .
Subject(s)
Humans , Ion Channels/metabolism , Patch-Clamp Techniques/methods , Cerebral Cortex/cytology , Cerebral Cortex/metabolism , Ion Channel Gating , Ion Channels/chemistry , Neurons/metabolism , Receptors, N-Methyl-D-Aspartate/chemistry , Receptors, N-Methyl-D-Aspartate/metabolismABSTRACT
Voltage is an important parameter that regulates the conductance of both intercellular and plasma membrane channels (undocked hemichannels) formed by the 21 members of the mammalian connexin gene family. Connexin channels display two forms of voltage-dependence, rectification of ionic currents and voltage-dependent gating. Ionic rectification results either from asymmetries in the distribution of fixed charges due to heterotypic pairing of different hemichannels, or by channel block, arising from differences in the concentrations of divalent cations on opposite sides of the junctional plaque. This rectification likely underpins the electrical rectification observed in some electrical synapses. Both intercellular and undocked hemichannels also display two distinct forms of voltage-dependent gating, termed Vj (fast)-gating and loop (slow)-gating. This review summarizes our current understanding of the molecular determinants and mechanisms underlying these conformational changes derived from experimental, molecular-genetic, structural, and computational approaches.
Subject(s)
Animals , Humans , Connexins/chemistry , Ion Channel Gating , Ion Channels/chemistry , Molecular Dynamics Simulation , Protein ConformationABSTRACT
The linear gramicidins are peptide antibiotics that form cation-selective channels in lipid bilayers. Gramicidin channels have very well-defined functional characteristics, and the structure of membrane-spanning gramicidin A channels is known at atomic resolution. These features make the gramicidins well suited to study how the amino acid sequence encodes the structure and function of a membrane-spanning channel. We show how one can use electrophysiological measurements to obtain structural information about conducting channels and to quantify the conformational preferences of sequence-substituted gramicidin mutants.
Subject(s)
Amino Acid Sequence , Gramicidin/chemistry , Ion Channels/chemistry , Lipid Bilayers/chemistry , Membrane Proteins/chemistry , Models, Molecular , Molecular Sequence Data , Protein Conformation , Protein FoldingABSTRACT
Los canales iónicos actúan acelerando el movimiento de los iones a través de las membranas biológicas. Cada canal iónico se activa por un estímulo específico (p. ej. eléctrico, mecánico, químico, etc.). Los receptores de membrana que actúan como canales iónicos (RMCI), pueden pasar a un estado denominado desensibilizado, cuando el agonista se encuentra ligado al receptor. El estado desensibilizado de un RMCI, como por ejemplo, el receptor nicotínico para la acetilcolina (nAChR), es un estado no funcional del canal y es un caso particular del denominado agotamiento de receptores "receptors rundown". La desensibilización de los RCMI sólo involucra una reducción de su actividad y no de su eliminación de la membrana. La desensibilización es importante en el control de la transmisión sináptica y en el desarrollo del sistema nervioso. En esta revisión se discuten los resultados más relevantes relacionados a su caracterización y modulación, de igual manera, algunos aspectos relacionados con los principales modelos cinéticos que le han tomado en consideración. Finalmente, se plantea la utilización de nuevas técnicas de biología molecular y electrofisiología para el estudio de la desensibilización y su importancia en los sistemas biológicos