Functional expression of P2 receptors in the inner ear of chicken embryo.

The purpose of the present study was to investigate the modulation of spontaneous afferent activity by ATP during embryonic development in a preparation isolated chicken inner ear. This work was performed using multiunit and single-unit extracellular recordings from the posterior semicircular canal nerve and the basilar papilla nerve. α,ß-meATP, a P2X receptor agonist, notably increased the discharge frequency of the vestibular afferents between E15 and E18, but not in the basilar papilla. In contrast, the P2Y receptor agonist UTP produced a slight increase in the discharge frequency of basilar papilla afferents, without apparent changes in the vestibular afferent activity. 2-MeSATP, a P2Y agonist, increased the basal discharge of the primary afferents in a dose-age dependent way, but when we applied the antagonist of P2Y receptor, Reactive Blue 2 (10(-4)M), the effect of 2-MeSATP decreased significantly. This was observed both in vestibule and basilar papilla. Using RT-PCR the presence of P2X3, P2Y1, P2Y2 and P2Y6 mRNA was documented in the vestibular system with more important presence during the early stage (E15) than the later stage (E21), however in the basilar papilla we found only the P2Y1, P2Y2 and P2Y6 mRNA with the same temporal course as in the vestibule. These results confirm our pharmacological findings. Together this data suggests a role for P2X receptors-mediated purinergic signaling in vestibular synaptic organization. Temporal changes in P2Y receptors during development might be involved in the establishment of the endolymphatic ion composition needed for normal vestibular and auditory transduction and/or specific cellular differentiation.

Excitatory actions of GABA in developing chick vestibular afferents: effects on resting electrical activity.

The aim of this study was to characterize the effect of γ-aminobutyric acid (GABA) in the resting multiunit activity of the vestibular afferents during development using the isolated inner ear of embryonic and postnatal chickens (E15-E21 and P5). GABA (10(-3) to 10(-5) M; n = 133) and muscimol (10(-3) M) elicited an increase in the frequency of the basal discharge of the vestibular afferents. We found that GABA action was dose-dependent and inversely related to animal age. Thus, the largest effect was observed in embryonic ages such as E15 and E17 and decreases in E21 and P5. The GABAA receptor antagonists, bicuculline (10(-5) M; n = 10) and picrotoxin (10(-4) M; n = 10), significantly decreased the excitatory action of GABA and muscimol (10(-3) M). Additionally, CNQX 10(-6) M, MCPG 10(-5) M and 7ClKyn 10(-5) M (n = 5) were co-applied by bath substitution (n = 5). Both the basal discharge and the GABA action significantly decreased in these experimental conditions. The chloride channel blocker 9-AC 0.5 mM produced an important reduction in the effect of GABA 10(-3) (n = 5) and 10(-4) M (n = 5). Thus, our results suggest an excitatory role of GABA in the resting activity of the vestibular afferents that can be explained by changes in the gradient of concentration of Cl(-) during development. We show for the first time that the magnitude of this GABA effect decreases at later stages of embryonic and early postnatal development. Taking into account the results with glutamatergic antagonists, we conclude that GABA has a presynaptic action but is not the neurotransmitter in the vestibular afferent synapses, although it could act as a facilitator of the spontaneous activity and may regulate glutamate release.

GABA: ¿dualidad funcional? Transición durante el neurodesarrollo / GABA: a functional duality? Transition during neurodevelopment

Introducción. El ácido gamma-aminobutírico (GABA) es el principal neurotransmisor de tipo inhibitorio y sus acciones son mediadas por receptores de tipo ionotrópico (GABAA) y metabotrópico (GABAB), ampliamente distribuidos en el tejido nervioso central. Objetivo. Revisar la estructura de los receptores GABA y su implicación en procesos fisiológicos en el sistema nervioso central. Desarrollo. Se aborda el estudio de la estructura y diversidad de los receptores GABA, especialmente durante el neurodesarrollo, y se hace referencia a la naturaleza excitatoria e inhibitoria de la transmisión gabérgica, donde la participación de los cotransportadores NKCC1 y KCC2 tiene un papel clave en dicha dualidad funcional en la transición de un estadio embrionario a uno posnatal. De igual forma, se plasma el interés por los receptores GABA como diana farmacológica de uso clínico, lo que se manifiesta por la presencia de sitios de modulación alostérica poco explorados en dicho complejo-receptor. Conclusiones. El conocimiento fisiológico y farmacológico de la gran diversidad de subunidades que conforman un determinado subtipo de receptor GABA, así como la correcta expresión en tiempo y espacio para garantizar la viabilidad de un organismo, prometen ser la respuesta a trastornos graves y añejos como la epilepsia o la drogadicción, y tan complejos como el neurodesarrollo (AU)

Introduction. Gamma-aminobutyric acid (GABA) is the most important inhibitory-type neurotransmitter and its actions are mediated by ionotropic (GABAA) and metabotropic (GABAB) type receptors, which are widely distributed throughout the tissue of the central nervous system. Aim. To review the structure of GABA receptors and their involvement in physiological processes in the central nervous system. Development. The study addresses the structure and diversity of the GABA receptors, especially during neurodevelopment, and reference is made to the excitatory and inhibitory nature of GABAergic transmission, where the participation of the cotransporters NKCC1 and KCC2 plays a key role in this functional duality in the transition from an embryonic to a postnatal state. Likewise, the interest in GABA receptors as a pharmacological target for clinical use is also discussed. This is manifested by the presence of under-explored allosteric modulation sites in the aforementioned complex-receptor. Conclusions. The physiological and pharmacological knowledge of the great diversity of subunits that make up a particular subtype of GABA receptor, as well as the correct expression in time and space in order to ensure the viability of the organism, promise to be the answer to long-time severe disorders like epilepsy or drug addiction, and such complex ones as neurodevelopment (AU)

Development of spontaneous activity and response properties of primary lagenar neurons in the chick.

Here, we report for the first time developmental changes in spontaneous activity and in response properties of single nerve fibers from the macular chick lagena. Such aspects are important in order to get insight into the functional role of the lagena which remains undetermined. For this purpose, we used intracellular and extracellular single-unit recording techniques in an isolated inner ear preparation from the chicken at ages E15 and P1. At E15, afferent fibers displayed a low irregular spontaneous discharge rate (41 +/- 14 spikes/s, CV = 1.17 +/- 0.1), which was replaced by regular high frequency spontaneous activity at P1 (CV = 0.48 +/- 0.8, 89 +/- 27 spikes/s). During the developmental period including E15, the percentage of silent neurons was 60% while that of P1 was 40%. The synaptic activity was higher at E15 than at P1. The action potential waveform generated at E15 had small amplitude and derivative depolarization, and consequently, a large duration in correlation with respect to action potential waveform at P1 (respectively: 53 +/- 2 vs. 65 +/- 3 mV, 60 +/- 11 vs. 109 +/- 20 mV/ms, 3.6 +/- 0.4 vs. 1.1 +/- 0.12 ms). In addition, we recognized two response dynamics to the injection of current steps: phasic, or rapidly adapting neurons and tonic, or slowly adapting neurons. Our results indicate similar developmental processes for the lagena as described for the vestibular system in other species, in agreement with the known morphological characteristics of this otholitic end organ. The presence of more than one subtype of afferent neuron also correlates with previous reports on vestibular afferents with analogous electrophysiological properties, strongly suggesting the vestibular nature of the lagena.

Carcinoma colorectal, incidencia transfusional transanestésica / Colorectal carcinoma: transanesthetic incidence of transfusions

El objetivo del presente trabajo fue determinar la incidencia transfusional transanestésica en pacientes oncológicos con carcinoma colorrectal sometidos a cirugía resectiva. Diseño: Serie de casos. Lugar: Departamento de Anestesiología Hospital de Oncología, CMN siglo XXI, IMSS. México, D.F. Pacientes: se revisaron 322 expedientes clínicos de pacientes con cáncer colorrectal y cirugía resectiva (colectomías). Las variables analizadas fueron: hemoglobina, hemotocrito pre y postoperatorias, sangrado, transfusión de algún componente sanguíneo durante el periodo transoperatorio y tiempo quirúrgico. Resultados: Solo 268 expedientes tuvieron la información transfunsional requerida. El sangrado promedio por cirugía fue 13.10 por ciento del volumen sanguíneo circulante. Del total de pacientes estudiados 57 por ciento fue transfundido con algún componente sanguíneo. Conclusiones: La incidencia transfunsional fue mayor a la esperada en relación al sangrado quirúrgico, condición que puede afectar el pronóstico de la neoplasia sobre la recurrencia tumoral o supervivencia

Componentes sanguineos en anestesia / Blood components and anesthesia

Dentro de la Anestesiología, la transfusión de componentes sanguíneos es práctica terapéutica frecuente no exenta de riesgos. En México la hemotransfusión se obtiene por donación altruista y se encuentra legislada. Antes de ser administrada, requiere de un proceso complejo en el que intervienen otras áreas del conocimiento humano así como otras especialidades médicas. El conocimiento de las indicaciones específicas para cada componente sanguíneo es clara y debe ser revisada por todo profesional involucrado en su aplicación y comprometido con brindar una mejor calidad de atención a sus pacientes. El objetivo de esta comunicación es ofrecer una guía práctica para anestesiólogos y cirujanos, con aspectos tecnológicos para consulta, que contribuyan a disminuir el numero de transfusiones innecesarias durante el transoperatorio

Total intravenous anesthesia with propofol vs. propofol/midazolam in oncology patients.

The goal of this study was to determine dose requirements of propofol vs. propofol/midazolam in oncology patients during total intravenous anesthesia. The design of the study was a controlled clinical trial. The setting was the Oncology Hospital, National Medical Center, IMSS, located in Mexico City. Sixty patients were allocated randomly into two groups, patients in control group received propofol and fentanyl to induced and to maintain the anesthesia. Twenty nine patients in the experimental group received propofol and midazolam to induce anesthesia and to maintain propofol and fentanyl. The combination of propofol and midazolam to induce general anesthesia in oncology patients reduced the requirements in propofol and fentanyl in total intravenous anesthesia.

Anestesia total endovenosa con propofol vs propofol/midazolam para el paciente oncológico / Total intravenous anesthesia with propofol vs propofol-midazolam for the oncological patients

El objetivo del presente trabajo fue el de determinar los requerimientos de propofol versus propofol/midazolam en pacientes oncológicos, durante anestesia total intravenosa. 60 pacientes fueron estudiados en dos grupos; 31 pacientes (grupo control) recibieron propofol y fentanyl para la inducción y mantenimiento de la anestesia, 29 pacientes (grupo experimental), recibieron propofol y midazolam para la inducción anestésica y propofol más fentanyl para el mantenimiento. La combinación de propofol y midazolam redujo los requisitos de propofol y fentanyl para anestesia total intravenosa en este grupo de pacientes

Evaluación del riesgo anestésico operatorio en pacientes odontológicos / Surgical anesthetic risk evaluation in dental patients

Las últimas décadas se han caracterizado por ser una carrera vertiginosa hacia el progreso de la ciencia. La medicina por consiguiente ha tenido cambios continuos, descubriéndose constantemente nuevas técnicas terapéuticas más efectivas que obligan a una actualización continua. La odontología es una rama que se encuentra íntimamente ligada a la anestesiología, la cirugía y la medicina interna. Por consiguiente una adecuada valoración integral de los pacientes que acuden al consultorio dental repercutirá en el éxito del tratamiento planeado