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Introducción: Durante las últimas décadas se ha estudiado la señal del electroencefalograma desde una perspectiva de matemática no-lineal. Esto permite entender la actividad eléctrica cerebral como un sistema dinámico complejo. Objetivo: Evaluar los exponentes de Hurst y sus correlaciones en la onda gamma durante una tarea de atención alternante e inhibición de la interferencia en estudiantes universitarios. Métodos: La muestra se constituyó por 14 alumnos de educación física. Para evaluar la actividad eléctrica cerebral se utilizó el dispositivo cerebro-interfaz Emotiv Epoc®. La atención alternante se estimó con el test de símbolos y dígitos, mientras que para la inhibición de la interferencia se empleó la prueba de palabras y colores de Stroop. Resultados: En la prueba de atención alternante, cuatro individuos revelaron mayor propensión al caos en el hemisferio derecho, uno presentó más tendencia en el hemisferio izquierdo y dos no tuvieron una predisposición definida. Por otra parte, durante la prueba de inhibición de la interferencia, cinco presentaron variaciones de las medias de Hurst entre las tres láminas del efecto Stroop, sobre todo de la región temporal. Los exponentes Hurst en ambas pruebas fueron inferiores a 0,5. Conclusiones: Durante la prueba de atención se observó un mayor caos de la actividad eléctrica cerebral, sin existir correlaciones entre las regiones estudiadas. Durante la prueba de inhibición las modificaciones de los exponentes de Hurst no presentaron patrones definidos hacia el orden o caos(AU)

Introduction: During the last decades the electroencephalogram signal has been studied from a nonlinear mathematical perspective. This allows understanding brain electrical activity as a complex dynamical system. Objective: To evaluate Hurst exponents and their correlations in the gamma wave during an alternating attention and interference inhibition task in university students. Methods: The sample consisted of 14 physical education students. The Emotiv Epoc® brain-interface device was used to evaluate brain electrical activity. Alternating attention was estimated with the symbols and digits test, while the Stroop words and colors test was used for interference inhibition. Results: In the alternating attention test, four individuals revealed a greater propensity to chaos in the right hemisphere, one showed a greater tendency in the left hemisphere and two had no defined predisposition. On the other hand, during interference inhibition, variations of Hurst average values between the three Stroop effect slices were determined in five subjects, especially in the temporal region. Hurst exponents in both tests were found to be less than 0.5. Conclusions: During the attention test, a greater chaos of brain electrical activity is observed, with no correlations between the regions studied. During the inhibition test, the modifications of the Hurst exponents do not present defined patterns towards order or chaos(AU)

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Cholinergic transmission is essential for survival and reproduction, as it is involved in several physiological responses. In the auditory system, both ascending and descending auditory pathways are modulated by cholinergic transmission, affecting the perception of sounds. The auditory efferent system is a neuronal network comprised of several feedback loops, including corticofugal and brainstem pathways to the cochlear receptor. The auditory efferent system's -final and mandatory synapses that connect the brain with the cochlear receptor- involve medial olivocochlear neurons and outer hair cells. A unique cholinergic transmission mediates these synapses through α9/α10 nicotinic receptors. To study this receptor, it was generated a strain of mice carrying a null mutation of the Chrna9 gene (α9-KO mice), lacking cholinergic transmission between medial olivocochlear neurons and outer hair cells, providing a unique opportunity to study the role of medial olivocochlear cholinergic transmission in auditory and cognitive functions. In this article, we review behavioral and physiological studies carried out to research auditory efferent function in the context of audition, cognition, and hearing impairments. Auditory studies have shown that hearing thresholds in the α9-KO mice are normal, while more complex auditory functions, such as frequency selectivity and sound localization, are altered. The corticofugal pathways have been studied in α9-KO mice using behavioral tasks, evidencing a reduced capacity to suppress auditory distractors during visual selective attention. Finally, we discuss the evolutionary role of the auditory efferent system detecting vocalizations in noise and its role in auditory disorders, such as the prevention of age-related hearing loss.

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This study proposes a hands-on activity as an experimental alternative method to teach biomedical engineering students the osmosis phenomenon. The students were guided along a learning path that involved their participation in the design and construction of a test device used to measure osmotic flow rate. Thereafter, an experiment was conducted with the test device. The students analyzed the obtained experimental values, which provided them with evidence of the functionality of the device. In addition, they were provided with the opportunity to suggest improvements and to propose alternatives to expand the use of the device to test other transport phenomena such as diffusion. Moreover, a student perception survey was conducted, and the results showed that this proposed plan allows for a better understanding of the phenomenon and stimulates the curiosity of students, improving the receptiveness, key in the learning process of the students.

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INTRODUCTION: Placenta accreta spectrum (PAS) causes severe morbidity and can result in maternal death. It must be managed in specialized centers with interdisciplinary groups, but few publications have described the usual management within a specific geographic region. We intend to describe the usual approach for PAS in reference centers in Latin America. METHODOLOGY: This was an observational, multicenter, cross-sectional study conducted in Latin American PAS reference centers. A standardized survey was implemented and applied to obstetric service coordinators and leaders of interdisciplinary groups with experience in PAS between September and November 2020. RESULTS: One hundred fifty-four hospitals were included. Most of them (64.3%) handle approximately one case of PAS every two months, and almost all centers (89.6%) believe that their performance could be improved. CONCLUSIONS: Most of the reference centers for PAS in Latin America attend to a small number of cases each year, and almost all of these hospitals identify opportunities to improve the management or approach for PAS in women.

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ANTECEDENTES: La pandemia global de COVID-19 llega al continente americano en marzo del año 2020 y en menos de dos meses reúne a más de la mitad de los casos a nivel global. OBJETIVO: Caso clínico de una mujer embarazada con una presentación crítica de COVID-19 y embarazo a las 25 semanas de gestación, en el contexto del peak de la pandemia en Chile en el otoño del año 2020. CASO CLÍNICO: El 20 de junio de 2020, una mujer de 34 años, con 25 semanas de embarazo, es trasladada desde Hospital de San Bernardo a Clínica Las Condes en Santiago, Chile, con un cuadro de 10 días de evolución de COVID-19, que evoluciona a una situación crítica con insuficiencia respiratoria severa. Ingresa a unidad de cuidados intensivos para ventilación mecánica. Las imágenes de radiología simple y de tomografía axial computarizada de tórax demuestran una neumopatía bilateral con imágenes características opacidades en vidrio esmerilado, asociado a engrosamiento intersticial, imágenes descritas previamente como características para COVID-19. La paciente permanece en unidad de cuidados intensivos en ventilación mecánica por siete días, con evolución favorable posterior, mejoría del cuadro séptico y alta después de 22 días de hospitalización. El parto ocurre en forma espontánea a las 38 semanas, la madre y el recién nacido evolucionan en buen estado general. El examen histopatológico placentario demuestra compromiso inflamatorio vellositario y los exámenes de anticuerpos en sangre del recién nacido demuestran la presencia de anticuerpos del tipo IgG e IgM. Se trata de uno de los pocos casos demostrados reportados de transmisión transplacentaria vía sanguínea de SARS-CoV-2 de la madre al recién nacido.

BACKGROUND: The global COVID-19 pandemic reaches the American continent in March 2020 and in less than two months it brings together more than half of the cases globally.OBJECTIVE: The clinical case of a 25-week pregnant woman with a critical presentation of COVID-19 and pregnancy at 25 weeks of gestation, is presented in the context of the peak of the pandemic in Chile in the fall of 2020. CLINICAL CASE: On June 20, 2020, a 34-year-old woman, 25 weeks pregnant, is transferred from Hospital de San Bernardo to Clinica Las Condes in Santiago, Chile, with a ten-day evolution of a COVID-19 that evolves to critical with severe respiratory failure. She is admitted to the intensive care unit for mechanical ventilation. Chest computerized axial tomography images demonstrate bilateral pneumopathy with characteristic images of ground-glass opacities, associated with interstitial thickening, images previously described as characteristics for COVID-19. The patient remains in the intensive care unit on mechanical ventilation for seven days, with subsequent favorable evolution, improvement of the septic condition, and discharge after 22 days of hospitalization. Delivery occurs at 38 weeks, the mother and the newborn evolve in good general condition. The placental histopathological examination demonstrates villous inflammatory involvement, and the newborn's blood tests show the presence of IgG and IgM antibodies. It is one of the few reported cases of transplacental transmission of SARS-CoV-2 from the mother to the newborn.

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Resumen Introducción. La actividad cerebral, teniendo en cuenta su dinámica aperiódica, puede ser estudiada mediante funciones no lineales o sistemas caóticos. Objetivo. Estudiar las diferencias inter e intra-hemisféricas de la relación orden/caos en la actividad cerebral de la onda beta en estudiantes universitarios durante la resolución de un test de atención. Materiales y métodos. La muestra estuvo compuesta por 10 estudiantes universitarios de educación física, todos hombres, a quienes se les aplicó la prueba de atención de Toulouse-Piéron para registrar, mediante electroencefalograma, su actividad cerebral por 8 minutos durante la ejecución de la prueba. Para el registro de la actividad cerebral se usó el dispositivo Emotiv Epoc®. Resultados. Se observaron diferencias intra e inter-hemisfericas en la relación orden/caos entre los participantes en las regiones prefrontales, temporales y occipitales (p<0.05), así como diversas correlaciones entre estas regiones (r>0.600), las cuales variaron tanto entre los sujetos, como a nivel individual a medida que avanzaba la ejecución de la prueba. Conclusión. A medida que la ejecución de la prueba avanzaba, las asimetrías hemisféricas aumentaban, por lo que es posible concluir que la participación en procesos cognitivos continuos produce diferencias en la actividad cerebral; sin embargo, es necesario realizar estudios similares en muestras con diferentes características (diversos grupos etarios, mujeres, etc.) y donde se apliquen otras pruebas de atención para poder confirmar o contrastar los resultados aquí reportados.

Abstract Introduction: Considering its aperiodic dynamics, brain activity can be studied by means of non-linear functions or chaotic systems. Objective: To analyze the inter- and intra-hemispheric differences of the order/chaos relationship observed in the beta waves of university students during their participation in an attention test. Materials and methods: The sample was composed of 10 university physical education students, all males, who were administered the Toulouse-Piéron Concentrated Attention Test to record, by means of electroencephalogram, their brain activity for 8 minutes during the execution of the test. The Emotiv Epoc® device was used to record brain activity. Results: Intra- and inter-hemispheric differences were observed in the order/chaos relationship among the participants in the prefrontal, temporal and occipital regions (p<0.05), as well as various correlations between these regions (r>0.600), which varied both between participants and individually as the execution of the test progressed. Conclusion: As the test progressed, hemispheric asymmetries increased, which allows concluding that engaging in continuous cognitive processes causes brain activity differences. However, it is necessary to carry out similar studies in samples with different characteristics (different age groups, women, etc.) in which other attention tests are used to confirm or contrast the results reported here.

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Los tumores cardiacos primarios fetales representan una entidad de baja incidencia en la práctica clínica. La gran mayoría corresponde a lesiones benignas, siendo el rabdomioma el tipo más común. Si bien, es frecuente la regresión espontánea de este tipo de lesiones durante el embarazo, los tumores cardiacos fetales pueden asociarse a complicaciones como obstrucción del flujo cardíaco, insuficiencia valvular, arritmias, insuficiencia cardíaca e hidrops fetal, pudiendo conducir incluso a la muerte fetal. El mayor desarrollo de técnicas imagenológicas ha permitido un aumento en el número y precisión de los diagnósticos prenatales de tumores cardiacos, generando al mismo tiempo, nuevos desafíos y alternativas en relación al abordaje terapéutico. El objetivo del presente artículo de revisión es exponer la evidencia actual en relación al diagnóstico prenatal, manejo, complicaciones y condiciones asociadas de los tumores cardiacos fetales más frecuentes.

Fetal primary cardiac tumors represent a low incidence entity in clinical practice. The vast majority corresponds to benign lesions, with rhabdomyoma being the most common type. Although spontaneous regression of this type of lesions during pregnancy is frequent, fetal cardiac tumors can be associated with complications such as obstruction of cardiac flow, valvular insufficiency, arrhythmias, heart failure and fetal hydrops, which can even lead to fetal death. The greater development of imaging techniques has allowed an increase in the number and precision of prenatal diagnoses of cardiac tumors, generating at the same time, new challenges and alternatives in relation to the therapeutic approach. The objective of this review article is to present the current evidence regarding the prenatal diagnosis, management, complications and associated condition s of the most frequent fetal cardiac tumors.

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AIM: To develop a combined predictive model for preterm and term pre-eclampsia (PE) during the first trimester of pregnancy. METHODS: This investigation was a nested case-control study in singleton pregnancies at the Maternal-Fetal Medicine Unit, University of Chile Hospital. A priori risks for preterm and term PE were calculated by multivariate logistic regression analyses. Biophysical markers were log10 -transformed and expressed as multiples of the median. A multivariate logistic regression analysis was used to estimate a combined predictive model of preterm and term PE. Detection rates at different cut-off points were determined by a receiver operator curve analysis of a posteriori risks. RESULTS: First trimester mean arterial pressure and uterine artery Doppler pulsatility index were significantly higher in women who develop PE than in the unaffected group. The detection rate of preterm PE based on maternal characteristics and biophysical markers was 72% at a 10% false-positive rate, corresponding to a cut-off risk of 1 in 50. The detection rate for term PE was 30% at a 10% false-positive rate. CONCLUSION: Preterm PE can be predicted by a combination of maternal characteristics and biophysical markers. However, first trimester screening is less valuable for term PE.

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OBJECTIVE: The aim of this article is to assess the use of the anterior cervical angle (ACA) as a predictor of spontaneous preterm delivery (sPTD) at 20+0-24+6 weeks of gestation in an unselected population. METHODS: We conducted a nested case-control study that included 93 women who later delivered spontaneously <34 weeks of gestation and 225 controls. The ACA was assessed retrospectively on all selected images using ImageJ® software. The concordance correlation coefficient was determined for the assessment of interobserver variability. Continuous variables were adjusted by maternal characteristics and expressed as the z-score or multiples of the expected normal median (MoM) of the unaffected group. Logistic regression analysis was used to evaluate whether any maternal characteristics and ultrasound variables were significantly associated with sPTD <34 weeks. RESULTS: ACA z-score values were significantly greater in women who later delivered <34 weeks compared to controls (ACA z-score = 1.32 ± 0.57 vs. -0.09 ± 0.35; p = 0.035). The best prediction of sPTD <34 weeks was provided by a model that combined cervical length (CL) MoM, ACA z-score and maternal characteristics. For a fixed false-positive rate of 10%, the detection rate for this model was 37.6%. CONCLUSION: A model combining maternal history, CL and ACA at 20+0-24+6 weeks of gestation can predict approximately 40% of the severe preterm births.

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BACKGROUND: The propofol pharmacokinetic model derived by Kataria et al. was recently modified to perform effect-site target-controlled infusion (TCI). Effect-site concentration (Ce) targets to induce general anesthesia with this model in children have not been described. The aim of this study was to identify propofol Ce targets associated with success rates of 50% (Ce50) and 95% (Ce95) among children 3-11 years of age. METHODS: Forty-two children were assigned to one of seven groups of six patients each according to propofol target Ce. After fentanyl administration propofol TCI was started with an assigned Ce target. A successful response was defined as loss of eyelash reflex and bispectral index < 50, 45 s after reaching the assigned Ce. Logistic regression analysis was performed to calculate propofol Ce50 and Ce95. RESULTS: Twenty-eight children had a successful response with the assigned propofol Ce. In these patients, a significant decrease in mean arterial blood pressure (79-59, P < 0.0001) and in heart rate (95-83, P < 0.0001) was observed. Propofol Ce and age showed a statistically significant effect in the logistic regression model. The overall calculated propofol Ce50 and Ce95 were 3.8 µg·ml(-1) (95% CI: 3.1-4.4 µg·ml(-1) ) and 6.1 µg·ml(-1) (95% CI: 4.6-7.6 µg·ml(-1) ), respectively. CONCLUSION: Our results identified useful propofol targets to be used with the Kataria effect-site model to induce anesthesia in children between 3 and 11 years. The recommended targets should be reduced progressively with increasing age most probably due to PK model misspecifications.

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