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Introducción: La medicina ancestral ha utilizado plantas con cualidades medicinales para prevenir y tratar enfermedades; aun cuando este tipo de investigaciones se han incrementado, son escasos los estudios con tubérculos andinos. Objetivo: Determinar la actividad biológica de extractos acuosos y etanólicos de los tubérculos andinos Tropaeolum tuberosum (mashua) y Ullucus tuberosus (melloco). Métodos: La investigación fue experimental y se desarrolló in vitro. La muestra estuvo constituida por 2 tubérculos andinos utilizados en la medicina ancestral. Se aplicaron técnicas de extracción en medio acuoso y etanólico. Los extractos fueron evaluados para determinar la actividad hemoaglutinante, anticoagulante y antimicrobiana con cepas ATCC. Resultados: Se demostró actividad hemoaglutinante en el extracto acuoso de T. tuberosum sobre eritrocitos A. Todos los extractos acuosos mostraron actividad anticoagulante, Tropaeolum tuberosum inhibió la actividad de la coagulación sanguínea (vía intrínseca) con un TTPa> 300 seg. Tanto los extractos acuosos y etanólicos exhibieron actividad antimicrobiana contra cepas ATCC, Tropaeolum tuberosum inhibió el crecimiento de Staphylococcus aureus 25923 con halos de 17 y 22 mm y Ullucus tuberosus (blanco) con halos de 10 y 30 mm, respectivamente. Los extractos acuosos de Tropaeolum tuberosum y Ullucus tuberosus (rojo) inhibieron el crecimiento de Candida tropicalis 66029 con halos de 27 y 12 mm y respectivamente. Conclusiones: Determinada la actividad biológica, se evidencia que los tubérculos andinos estudiados aglutinan eritrocitos humanos, específicamente eritrocitos del grupo A, así mismo, capacidad de inhibir las proteínas plasmáticas de la coagulación y de inhibir el crecimiento bacteriano y micótico de cepas ATTC.

Introduction: Ancestral medicine has used plants with medicinal qualities to prevent and treat diseases, even though this type of research has increased, studies with Andean tubers are scarce. Objective: To determine the biological activity of aqueous and ethanolic extracts of the Andean tubers Tropaeolum tuberosum (mashua) and Ullucus tuberosus (melloco). Methods: The research was experimental and was developed in vitro. The sample consisted of 2 Andean tubers used in ancestral medicine. Extraction techniques were applied in aqueous and ethanolic medium. The extracts were evaluated for hemagglutinating, anticoagulant and antimicrobial activity with ATCC strains. Results: Hemagglutinating activity was demonstrated in the aqueous extract of T. tuberosum on A erythrocyte. All aqueous extracts showed anticoagulant activity, Tropaeolum tuberosum inhibited blood coagulation activity (intrinsic pathway) with an aPTT>300 sec. Both aqueous and ethanolic extracts exhibited antimicrobial activity against ATCC strains, Tropaeolum tuberosum inhibited the growth of Staphylococcus aureus 25923 with halos of 17 and 22 mm and Ullucus tuberosus (white) with halos of 10 and 30 mm, respectively. The aqueous extracts of Tropaeolum tuberosum and Ullucus tuberosus (red) inhibited the growth of Candida tropicalis 66029 with halos of 27 and 12 mm, respectively. Conclusions: Once the biological activity was determined, it was evident that the Andean tubers studied agglutinated human erythrocytes, specifically group A erythrocytes, as well as the ability to inhibit plasma coagulation proteins and inhibit the bacterial and fungal growth of ATTC strains.

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This paper shows the design of an injector, using carbon nanotubes as inkjet material, implemented in a 3D printer. According to the available literature, few injectors are capable of depositing material. Due to the lack of information, the central part of this research is to develop a suitable device for ink injection that is capable of applying the Fused Deposition Modeling (FDM) method to print nanomaterial ink. The injector was designed using a CAD program based on an open-source desktop 3D printer, which allows it to be modified according to the needs of the injector. This prototype was manufactured in aluminum alloy 7075T6. Computational fluid dynamics (CFD) were carried out to analyze the behavior of the fluid when it passes through the injector, obtaining parameters such as pressure, velocity, and vorticity. An experimental matrix of the injector operation was carried out to achieve an adequate printing speed. The results show that the optimum speed was 250 ms, considering that a temperature of 100 °C is needed in the heated bed to dry the ink so that it does not undergo expansion.

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RESUMEN Los briófitos forman un grupo conspicuo de la flora del planeta. Su contribución ecológica en términos de riqueza de especies y cobertura en muchos hábitats es fundamental para el equilibrio de los servicios ecosistémicos. En Colombia se tiene el registro aproximado de 715 especies de Marchantiophyta (hepáticas), las cuales presentan su mayor riqueza en la región Andina. El estudio se realizó en el Parque Nacional Natural Chingaza - sector Suasie dada su importancia ecológica e hídrica para los municipios aledaños. El objetivo principal de este estudio fue determinar la diversidad de la comunidad de hepáticas en el sector de Suasie del PNN Chingaza. Para ello, se hicieron tres levantamientos en transectos de 2x50 m en un gradiente altitudinal, en cada transecto se muestrearon las hepáticas presentes en cuatro forófitos escogidos al azar. Las muestras recolectadas fueron identificadas para el análisis de composición y diversidad de la comunidad. Como resultado, fue posible evidenciar la variación de la composición y abundancia de hepáticas a lo largo del gradiente, basados no solo en los índices estimados, sino también en la asociación con la cobertura vegetal de cada sitio de muestreo. Con un total de 47 especies registradas, se soporta la alta diversidad del sector en estudio. De esta manera, la riqueza encontrada en este gradiente aporta a las actuales y futuras estrategias de conservación del parque.

ABSTRACT The bryophytes form a conspicuous group of the planet's flora, their ecological contribution in terms of species richness and coverage in many habitats is essential for the balance of ecosystem. In Colombia there is an approximate record of 715 species of Marchantiophyta (liverworts), which present their greatest richness in the Andean region. The study was carried out in the Chingaza National Natural Park - Suasie sector given its ecological and water importance for the surrounding municipalities. The main objective of this study was to determine the diversity of the liverwort community in the Suasie sector of the Chingaza NNP. For this, three surveys were made in transects of 2x50 m in an altitude gradient, in each transect the liverworts present from four phorophytes (trees and shrubs), chosen at random were sampled. The collected samples were identified for analysis of composition and diversity of the community. As a result, it was possible to demonstrate the variation in the composition and abundance of liverworts along the gradient, based not only on the estimated indices, but also on the association with the vegetation cover of each sampling site. With a total of 47 registered species, the high diversity of the sector under study is supported. In this way, the richness found in this gradient contributes to current and future conservation strategies for the park.

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BACKGROUND: Scientific research is fundamental to the education of medical students. However, their involvement in research is limited. AIM: To describe the perceptions of medical students about facilitators and constraints to perform undergraduate research. MATERIAL AND METOHDS: Medical students attending the Chilean Congress of Medical Students in the Metropolitan Region in 2018, were surveyed. The responses obtained were subjected to a qualitative content analysis and were grouped according to perceptions of facilitators and constraints. RESULTS: The main facilitators reported were linkage with research teachers, personal motivation towards research, and research-oriented curriculum. The main constraints were lack of time for research, lack of access to formal information channels to engage in research, and sub-optimal conditions for research. CONCLUSIONS: The main factor promoting research at the undergraduate level was the link with the teacher, mainly through informal channels. The lack of official information provided through formal instances and lack of time hampers the access to research.

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BACKGROUND: Scientific research is fundamental to the education of medical students. However, their involvement in research is limited. AIM: To describe the perceptions of medical students about facilitators and constraints to perform undergraduate research. MATERIAL AND METHODS: Medical students attending the Chilean Congress of Medical Students in the Metropolitan Region in 2018, were surveyed. The responses obtained were subjected to a qualitative content analysis and were grouped according to perceptions of facilitators and constraints. RESULTS: The main facilitators reported were linkage with research teachers, personal motivation towards research, and research-oriented curriculum. The main constraints were lack of time for research, lack of access to formal information channels to engage in research, and sub-optimal conditions for research. CONCLUSIONS: The main factor promoting research at the undergraduate level was the link with the teacher, mainly through informal channels. The lack of official information provided through formal instances and lack of time hampers the access to research.

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RESUMEN: Los programas de intervención para prevenir o tratar el Síndrome de Burnout son esenciales para mejorar la salud de los estudiantes. Pero la mayoría de las investigaciones realizadas son intervenciones psicológicas y cognitivas.Objetivo: Determinar los efectos de los ejercicios físicos en los niveles de Síndrome de Burnout y la Variabilidad de la Frecuencia Cardíaca en estudiantes universitarios.Métodos: Estudio experimental con pre-test y post-test, con 2 grupos de intervención y un grupo de control. La muestra fue probabilística y estratificada con participación proporcional. Instrumentos utilizados: Maslach Burnout Inventory Students Survey (MBI-SS) y Variabilidad de la Frecuencia Cardíaca (HRV): cálculo de la media RR, SDNN y RMSSD. Para el ejercicio físico, se aplicaron ejercicios aeróbicos y de fuerza durante 3 sesiones semanales de una hora, en días alternos, durante 16 semanas.Resultados: El grupo de aeróbicos con Agotamiento MBI-SS fue mayor, reduciendo sus niveles en un 26,4% (d=0,532), en Cinismo (-21,06, d=0,252) y en Eficacia (-13,11, 0,397). Grupo de fuerza en Cinismo (-27,38, d=0,315), en Eficacia (-21,69, d=0,704), Agotamiento (-19,55, d=0,299). El grupo de control Agotamiento aumentó en un 10,26% (d=0,128). En la HVR, con el grupo aeróbico el SDNN tuvo el mayor cambio porcentual, con un aumento del 24,82 %, sobre la media RR y RMSSD (14,40 % y 16,45 %). En el grupo de fuerza y en el grupo de control (21,77%, 14,24%, 12,60%; y 12,59%, 4,97% y 4,99% respectivamente). Hubo un cambio en el RR medio en los grupos aeróbico y de fuerza (d = 1,281 y 1,328).Conclusiones: Efecto de reducción del síndrome de burnout y efecto contrario de incremento de valores del HRV. (AU)

ABSTRACT: Intervention programs to prevent or treat Burnout Syndrome are essential to improve the health of students. But most of the research that has been done is psychological and cognitive interventions.Objective: To determine the effects of physical exercises on Burnout Syndrome levels and Heart Rate Variability in university students.Methods: An experimental study was carried out with pre-test and post-test, with 2 intervention groups and a control group. The sample was probabilistic and stratified with proportional participation. Study variables and instruments were included: Maslach Burnout Inventory Students Survey (MBI-SS) and Heart Rate Variability (HRV): calculation of the average RR, SDNN and RMSSD. For physical exercise, aerobic and strength exercises were applied during 3 weekly sessions of one hour, on alternate days, for 16 weeks.Results: The group of aerobics with MBI-SS exhaustion was higher, reducing its levels by 26.4% (d=0.532), in Cynicism (-21.06, d=0.252) and Efficiency (-13.11, 0.397). Force group in Cynicism (-27.38, d=0.315), in Efficiency (-21.69, d=0.704), Exhaustion (-19.55, d=0.299). The Exhaustion control group increased by 10.26% (d=0.128). In HVR, with the aerobic group, NDL had the greatest percentage change, increasing 24,82 %, over the average RR and RMSSD (14,40 % and 16,45 %). In the force group and in the control group (21.77%, 14.24%, 12.60%; and 12.59%, 4.97% and 4.99% respectively) there was a change in the mean RR in the aerobic and strength groups (d = 1.281 and 1.328).Conclusions: Effect of reduction of burnout syndrome and opposite effect of increase of HRV values. (AU)

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Background: The participation of medical students in research generates professional, scientific, and personal benefits for the student. Aim: To evaluate the interest and opportunities for medical students in Chile to participate in scientific research and their perceptions about factors influencing research. Material and Methods: All students attending the 2018 Chilean Congress for Medical Students were invited to answer a 44 questions survey about interest and opportunities to participate in research. Results: The survey was answered by 489 of the 538 students attending the congress. Eighty five percent referred interest in conducting scientific research, but only 47% had the opportunity to actively participate in a research project. The main research area providing opportunities was epidemiology and the main form to access a research project was through direct contact with a medical professor or researcher. Seventy seven percent of respondents had courses of scientific investigation in their medical curriculum and 92% had a scientific society for medical students in their university. Conclusions: Respondents showed a great deal of interest in participating in scientific research. However, there is a gap between this interest and the available opportunities. Medical professors should promote and facilitate the participation of their students in research.

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Snake species within the Bothrops complex (sensu lato) are of medical relevance in Latin America, but knowledge on their venom characteristics is limited, or even unavailable, for some taxa. Perú harbors 17 species of pit vipers, within the genera Bothrops, Bothriechis, Bothrocophias, Porthidium, Crotalus, and Lachesis. This study compared the venoms of twelve species, through chromatographic and electrophoretic profiles, as well as proteolytic and phospholipase A2 (PLA2) activities. Also, proteomic profiles were analyzed for nine of the venoms using a shotgun approach. Results unveiled conspicuous differences in the expression of venom PLA2s among species, six of them presenting scarce levels as judged by RP-HPLC profiles. Since most species within the bothropoid lineage possess venoms with high to intermediate abundances of this protein family, our findings suggest the existence of a phenotypic duality in the expression of venom PLA2s within the Bothrops (sensu lato) complex. Bothrops barnetti and Bothrocophias andianus venoms, very scarce in PLA2s, were shown to lack significant myotoxic activity, highlighting that the observed variability in PLA2 expression bears toxicological correlations with effects attributed to these proteins. Finally, an attempt to identify phylogenetic relationships of bothropoid species from Perú presenting low- or high-PLA2 venom phenotypes showed an interspersed pattern, thus precluding a simple phylogenetic interpretation of this venom compositional dichotomy.

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Resumen La prevalencia de la enfermedad arterial coronaria compleja en la población mundial es alta. Las oclusiones coronarias crónicas totales (OCT) generan gran morbilidad en la población y significan un reto terapéutico por su alta complejidad. En años recientes con el desarrollo de nuevas tecnologías se ha visto a nivel mundial un beneficio en la calidad de vida, síntomas y función sistólica del ventrículo izquierdo al realizar intervención coronaria percutánea (ICP) de las OCT con una alta tasa de éxito y pocas complicaciones. En este trabajo se describen los resultados clínicos cardiovasculares a un año de realizar ICP en pacientes con OCT intervenidos en el Hospital México en Costa Rica durante 2016-2017. Se registraron 54 pacientes con seguimiento de 1 año posterior a ICP de OCT. Se analizaron variables sociodemográficas y clínicas, cuantificando síntomas según la escala funcional de la Asociación de Corazón de Nueva York (NYHA) y la Sociedad Canadiense de Cardiología (CCS) de angina, así como valoración de la fracción de eyección (FE) por ecocardiografía en forma basal y posterior a la ICP, y las complicaciones asociadas De los 54 pacientes sometidos a ICP de OCT, la mayoría fueron hombres con edad promedio de 64 años y nivel académico básico. No hubo diferencia significativa en la FE previo y posterior al procedimiento (p=0.68), con una tendencia a la mejoría en los pacientes con disfunción sistólica severa con tejido viable. Sí hubo diferencias significativas en mejoría de síntomas basados en la escala funcional NYHA (p<0,01) y la escala de angina CCS (p<0,01). Se alcanzó un éxito en el procedimiento en el 96.3% de los casos sin diferencia significativa según el acceso vascular ni la escala J-CTO con una tasa de complicaciones baja. Concluimos que hay un beneficio clínico significativo en cuanto a los síntomas, al revascularizar a pacientes con oclusiones coronarias crónicas totales, con una alta tasa de éxito en el procedimiento y pocas complicaciones.

Abstract There is a high prevalence of complex coronary artery disease worldwide, in this group chronic total occlusions (CTO) generate a great burden of disease in the population and are a difficult therapeutic challenge. In recent years and with the development of new technologies, the world have seen a benefit in quality of life, symptoms and systolic function of the left ventricle when performing a percutaneous coronary intervention (PCI) of CTO with high success rate and low rate of complications. In this study we describe the cardiovascular clinical results one year after performing PCI in patients with CTOs in Hospital Mexico in Costa Rica during 2016-2017. Methods: We registry 54 patients completing one year follow up after PCI of CTO. We measure sociodemographic and clinical variables quantifying symptoms using NYHA and CCS scales, ejection fraction (EF) using echocardiography previous and after PCI, and the complications developed. We identified 54 patients who underwent PCI of CTO, most were men with an average age of 64 years and a basic academic level. There was no significant difference in the pre-and-post-procedure EF (p=0.68), with a trend to improvement in patients with severe left ventricle systolic dysfunction and viable myocardium. There were significant differences in symp- tom improvement based on the NYHA functional status score (p<0.01) and the CCS angina score (p<0.01). A successful procedure was achieved in 96.3% of cases with no significant difference depending on vascular access or the J-CTO scale with low complication rate. Conclusions: There is a significant clinical benefit based on symptoms of performing PCI in patients with CTO with a high success rate in the procedure and a few associated complications.

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