Marcela Bitran

Bio: Marcela Bitran is an academic researcher from Pontifical Catholic University of Chile. The author has contributed to research in topics: Neuropeptide Y receptor & Cronbach's alpha. The author has an hindex of 13, co-authored 36 publications receiving 434 citations. Previous affiliations of Marcela Bitran include University of Toronto & University of Chile.

Learning factor in rapid tolerance to ethanol-induced motor impairment.

Abstract: Exposure of male Wistar rats to a single moderate dose (1.7 g/kg, IP) of ethanol (EtOH), followed by intensive intoxicated practice on the moving belt apparatus (a total of 12 min during the first hour after EtOH injection), results in functional tolerance to the motor-impairing effects of a second dose given either 8 or 24 h later. In the absence of intoxicated practice, or after a considerably reduced opportunity for it (a total of 4 min during the first hour after EtOH injection), the same dose of EtOH fails to produce tolerance. Thus, not only the opportunity to practice, but also its extent and possibly its quality are important determinants in the rapid development of intersessional tolerance. In contrast to its rapidity of development, no significant loss of this tolerance is evident three weeks after the tolerance acquisition sessions.

Medical students' change in learning styles during the course of the undergraduate program: from 'thinking and watching' to 'thinking and doing'

Abstract: Background: Most students admitted to medical school are abstract-passive learners. However, as they progress through the program, active learning and concrete interpersonal interactions become crucial for the acquisition of professional competencies. The purpose of this study was to determine if and how medical students' learning styles change during the course of their undergraduate program. Methods: All students admitted to the Pontificia Universidad Catolica de Chile (PUC) medical school between 2000 and 2011 (n = 1,290) took the Kolb’s Learning Style Inventory at school entrance. Two years later 627 students took it again, and in the seventh and last year of the program 104 students took it for a third time. The distribution of styles at years 1, 3 and 7, and the mobility of students between styles were analyzed with Bayesian models. Results: Most freshmen (54%) were classified as assimilators (abstract-passive learners); convergers (abstractactive) followed with 26%, whereas divergers (concrete-passive) and accommodators (concrete-active) accounted for 11% and 9%, respectively. By year 3, the styles' distribution remained unchanged but in year 7 convergers outnumbered assimilators (49% vs. 33%). In general, there were no gender-related differences.

Psychological types and learning styles of students entering medical school at the Pontificia Universidad Católica de Chile

Abstract: o-reflexivas tenganventajas en el ciclo basico de la carrera y los concreto-activos en el ciclo clinico e internado. Dehecho, se han reportado diferencias en la habilidaddiagnostica de aprendices abstractos y concretos 31 ,destacandose los abstractos por su capacidad deestructurar el pensamiento y los concretos por suflexibilidad de pensamiento.C ONCLUSIONES GENERALES En resumen, de cada 10 estudiantes que ingresana estudiar medicina en la PUC, 7 se caracterizanpor analizar la informacion de un modo logico,objetivo e imparcial o por tener una posturaestructurada y decidida en la vida. El fuerte deestos estudiantes es la capacidad de asimilar grancantidad de informacion y abstraer los conceptosy patrones generales. Tienen una tendencia masreflexiva que activa, por lo que evaluanexhaustivamente las alternativas de accion.Por otra parte, 30% que posee el perfil opues-to, basa sus decisiones en consideraciones perso-nales, privilegia la armonia entre las personas, ytiene una actitud flexible y abierta ante la vida ysus posibilidades. Las fortalezas de estos estudian-tes residen en su capacidad para aprender de laexperiencia directa y trabajar en equipo; en suaprecio y cuidado por los detalles, y en suvaloracion de las relaciones interpersonales.Sin lugar a dudas, las caracteristicas de personali-dad y estilos de aprender atraviesan la vida academicade cada estudiante, influyendo en la adquisicion tantode conocimientos como de habilidades y actitu-des

Validation of a Spanish Version of the Mental Health Continuum-Short Form Questionnaire.

Abstract: espanolAntecedentes: el Mental Health Continuum-Short Form (MHC-SF) es un instrumento multidimensional disenado para evaluar los componentes emocional, psicologico y social del bienestar personal. Ha sido traducido a varios idiomas; sin embargo, no hay una version validada en espanol. Nuestro objetivo fue proveer a la comunidad hispanoparlante de una version valida del MHC-SF. Metodo: MHC-SF se tradujo al espanol (s-MHC-SF) y se aplico a una muestra de 3.355 adultos chilenos. Se realizo un analisis factorial confirmatorio usando el modelo original de tres factores correlacionados y un modelo bifactorial recientemente descrito. Resultados: los puntajes obtenidos con el s-MHC-SF mostraron alta confiabilidad (α = .94). Mientras el modelo correlacionado presento un ajuste aceptable a los datos, el bifactorial mostro un ajuste superior. Segun las pruebas de invarianza de medicion, ambos modelos podrian ser utilizados para comparar puntajes segun sexo, edad, region geografica y tiempo en la muestra. Conclusion: s-MHC-SF es un cuestionario valido para evaluar el bienestar en la poblacion de habla hispana. EnglishBackground: The Mental Health Continuum-Short Form (MHC-SF) is a multidimensional measure of well-being designed to assess emotional, psychological and social well-being. It has been translated into different languages; however, there is no validated Spanish version. Our aim was to provide the Spanish-speaking community with a validated version of the MHC-SF. Method: We translated the questionnaire into Spanish (s-MHC-SF) and assessed its validity in a sample of 3,355 Chilean adults. The data was subjected to a confirmatory factor analysis using the original correlated-traits three-factor model and a recently described bifactor model. Results: The scores obtained with s-MHC-SF had excellent reliability (α = .94). While the correlated-traits three-factor model provided an acceptable fit to the data, the bifactor model yielded a superior fit. According to measurement invariance results, both models could be used to compare scores over gender, geographical region, age, and time in the sample. Conclusion: s-MHC-SF is a valid questionnaire for the evaluation of personal well-being in Spanish-speaking populations.

Influence of personality and learning styles in the choice of medical specialty

Abstract: Background: Several studies indicate that doctors who work in the same area of the medical profession tend to behave somehow similarly. Thus, it has been suggested that personality relates to the medical specialty choice. However, it is not known whether people selfselect into the medical specialties according to their personality or the professional practice in a particular field influences their behavior. Aim: To explore the possible association between the graduate’s personality features and learning styles and their chosen specialty. Subjects and Methods: The psychological preferences and learning styles of 65 students of the 2001-graduating cohort of the Pontificia Universidad Catolica de Chile School of Medicine were evaluated with the Myers Briggs Type Indicator and the Kolb Learning Style Inventory, respectively. These variables were correlated with the information of their specialty choice or occupation two years after graduation. Results: Graduates distributed unevenly in different areas of the medical profession. Surgical specialties concentrated a larger proportion of extraverted, intuitive and structured doctors, whereas in Pediatrics and Internal Medicine predominated intuitive and people-oriented MD’s. Primary Care concentrated individuals with introverted, intuitive and flexible attitudes. Convergent learners (interested in problem-solving) preferred Surgery and Primary Care whereas Assimilator learners

Generation of the Melatonin Endocrine Message in Mammals: A Review of the Complex Regulation of Melatonin Synthesis by Norepinephrine, Peptides, and Other Pineal Transmitters

Abstract: Melatonin, the major hormone produced by the pineal gland, displays characteristic daily and seasonal patterns of secretion. These robust and predictable rhythms in circulating melatonin are strong synchronizers for the expression of numerous physiological processes in photoperiodic species. In mammals, the nighttime production of melatonin is mainly driven by the circadian clock, situated in the suprachiasmatic nucleus of the hypothalamus, which controls the release of norepinephrine from the dense pineal sympathetic afferents. The pivotal role of norepinephrine in the nocturnal stimulation of melatonin synthesis has been extensively dissected at the cellular and molecular levels. Besides the noradrenergic input, the presence of numerous other transmitters originating from various sources has been reported in the pineal gland. Many of these are neuropeptides and appear to contribute to the regulation of melatonin synthesis by modulating the effects of norepinephrine on pineal biochemistry. The aim of this review is firstly to update our knowledge of the cellular and molecular events underlying the noradrenergic control of melatonin synthesis; and secondly to gather together early and recent data on the effects of the nonadrenergic transmitters on modulation of melatonin synthesis. This information reveals the variety of inputs that can be integrated by the pineal gland; what elements are crucial to deliver the very precise timing information to the organism. This also clarifies the role of these various inputs in the seasonal variation of melatonin synthesis and their subsequent physiological function.