[Diagnostic and formative assessment of competencies at the beginning of undergraduate medical internship]. / valuación diagnóstica y formativa de competencias en estudiantes de medicina a su ingreso al internado médico de pregrado.

INTRODUCTION: Research on diagnostic and formative assessment competencies during undergraduate medical training is scarce in Latin America. OBJECTIVE: To assess the level of clinical competence of students at the beginning of their medical internship in a new curriculum. METHODS: This was an observational cross-sectional study in UNAM Faculty of Medicine students in Mexico City: a formative assessment of the second class of Curriculum 2010 students as part of the integral evaluation of the program. The assessment had two components: theoretical and practical. RESULTS: We assessed 577 students (65.5%) of the 880 total population that finished the 9th semester of Curriculum 2010. The written exam consisted of 232 items, with a mean of 61.0 ± 19.6, a difficulty index of 0.61, and Cronbach's alpha of 0.89. The mean of the objective structured clinical examination (OSCE) was 62.2 ± 16.8, with a mean Cronbach's alpha of 0.51. Results were analyzed by knowledge area and exam stations. CONCLUSIONS: The overall results provide evidence that students achieve sufficiently the competencies established in the curriculum at the beginning of the internship, that they have the necessary foundation for learning new and more complex information, and integrate it with existing knowledge to achieve significant learning and continue their training.

[Morphology in biomedical sciences]. / La morfología en las ciencias biomédicas.

Morphology in biomedical sciences in the modern curriculum includes anatomy, embryology and cellular and tissular biology, and medical histology. Anatomy is taught in a traditional manner, however teaching with corpses will have to change because of the increasing difficulty of obtaining them for teaching purposes. In embryology, the major challenge is to help the student to understand the 3D rotations that happen during normal intrauterine development. For cellular and tissular biology and medical histology, the need for an increased contextual orientation will show the student why this course is important for the clinician. Core curriculum, in addition to textbooks containing basic information that students will have the time to read, is highly recommended, and finally we have to invest more time in formative rather than in storage of knowledge in the students' memory.

[Diagnostic assessment of knowledge and competencies in medical students at the end of the second year of medical school: the challenge of building an airplane while it's flying]. / Evaluación diagnóstica de conocimientos y competencias en estudiantes de medicina al término del segundo año de la carrera: el reto de construir el avión mientras vuela.

INTRODUCTION: In Latin America there is almost no published information about knowledge retention and formative assessment of competencies in medical students, during medical school training and curricular changes. OBJECTIVE: To assess knowledge level and clinical competencies in medical students at the end of the second year in a new curriculum. METHODS: Observational, cross-sectional study in UNAM Faculty of Medicine students. A diagnostic evaluation was performed in the first class of the "Plan of Studies 2010" curriculum, as part of an integral program evaluation strategy. The assessment had two components: theoretical and practical. RESULTS: 456 (87%) of the 524 students that successfully completed the second year of Plan 2010 were assessed. The written test had 211 items, a mean score of 60 ± 14.5, mean difficulty index of 0.60, reliability with Cronbach's alpha of 0.85. The OSCE mean global score was 58 ± 9, Cronbach's alpha of 0.36, and G-coefficient of 0.48, and results were provided for each station. Results by area of knowledge, course, and station were reported. CONCLUSIONS: The results in general are acceptable, compared with previous written evaluations at the end of the second year, suggesting that the new program is achieving its educational goals. Competencies were formally assessed for the first time in our Institution, establishing a starting point for follow-up. The study provided useful information to the institution, teachers and students.

Neuroendocrine cells are present in the domestic fowl ovary.

Neuroendocrine cells are present in virtually all organs of the vertebrate body; however, it is yet uncertain whether they exist in the ovaries. Previous reports of ovarian neurons and neuron-like cells in mammals and birds might have resulted from misidentification. The aim of the present work was to determine the identity of neuron-like cells in immature ovaries of the domestic fowl. Cells immunoreactive to neurofilaments, synaptophysin, and chromogranin-A, with small, dense-core secretory granules, were consistently observed throughout the sub-cortical ovarian medulla and cortical interfollicular stroma. These cells also displayed immunoreactivity for tyrosine, tryptophan and dopamine ß-hydroxylases, as well as to aromatic L-DOPA decarboxylase, implying their ability to synthesize both catecholamines and indolamines. Our results support the argument that the ovarian cells previously reported as neuron-like in birds, are neuroendocrine cells.

[Impact of problem-based learning on the cognitive processes of medical students]. / Impacto del aprendizaje basado en problemas en los procesos cognitivos de los estudiantes de medicina.

The problem based learning (PBL) method was conceived as a teaching strategy to be applied in different areas or disciplines, thus several universities adopted it, among which was the Universidad Nacional Autónoma de México, best known as UNAM. The Faculty of Medicine of UNAM implemented this innovative teaching method of medicine for its learner-centered educational method tendency (patient-centered practice). This method develops also several abilities in the students, such as active and significant learning, seeking and data selection and autoanalysis and synthesis, knowledge integration of, mind's logic for the detection and solution of problems, among others. The aim was to evaluate the PBL impact on pedagogical and cognitive processes through the students' critical thinking and the significance of the experience on students and teachers which were working with PBL; in addition, study strategies and self-regulation in students were considered variables for the study. Our findings indicated that PBL was perceived differently among students and teachers, and it influenced in a positive and significant way the students' perception to solve problems and their motivation to achieve a good academic performance (p < 0.005). These results suggest that PBL is a useful strategy in the teaching and learning process and it is clear that the pedagogical process and other variables can potentially influence the results obtained.

[Signaling pathways involved in megakaryopoiesis]. / Vías de señalización implicadas en la megacariopoyesis.

Hematotoxicology has been studied with less interest than other fields associated with atmospheric pollution. There is limited knowledge about on the effects that certain atmospheric pollutants may provoke in the blood and bone marrow. Suspended particle pollution has become an area of scientific inquiry due to the contaminants adhering to its surface. We have identified the association of inhaled vanadium and variations in megakaryopoyesis and thrombopoyesis. Platelets are the smallest elements in the blood, but they play a strategic role in hemostasis. They are derived from the largest cell of the bone marrow, the megakaryocite. This cell size is about 150 microm, with apolyploid nucleus and unknown origin until few years ago. When TPO was cloned in 1994 the knowledge about megakaryocyte began to growth exponentially, elucidating the mechanisms of proliferation, differentiation and release of platelets. More information is still needed in order to translate knowledge into clinical application for diseases such as thrombocytopenia or thrombocytosis. A review of the current concepts of megakaryopoiesis and its regulation, with emphasis on signaling pathways are presented in this paper; a classification in TPO-dependent and TPO-independent is also detailed. In addition, we review some diseases associated with changes in the signaling pathway of megakaryopoyesis, as well as possible perspectives in this field, including toxicology.

Cytoplasmic calcium mediates oxidative damage in an excitotoxic /energetic deficit synergic model in rats.

Excessive calcium is responsible for triggering different potentially fatal metabolic pathways during neurodegeneration. In this study, we evaluated the role of calcium on the oxidative damage produced in an in vitro combined model of excitotoxicity/energy deficit produced by the co-administration of quinolinate and 3-nitropropionate to brain synaptosomal membranes. Synaptosomal fractions were incubated in the presence of subtoxic concentrations of these agents (21 and 166 microm, respectively). In order further to characterize possible toxic mechanisms involved in oxidative damage in this experimental paradigm, agents with different properties - dizocilpine, acetyl L-carnitine, iron porphyrinate and S-allylcysteine - were tested at increasing concentrations (10-1000 microm). Lipid peroxidation was assessed by the formation of thiobarbituric acid-reactive substances. For confirmatory purposes, additional fractions were incubated in parallel in the presence of the intracellular calcium chelator 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid-acetoxymethyl ester (BAPTA-AM). Under physiological conditions of extracellular calcium availability, synaptomes exposed to both toxins displayed an increased lipoperoxidation (76% above controls), and this effect was partially attenuated by the tested agents as follows: dizocilpine = iron porphyrinate > acetyl L-carnitine > S-allylcysteine. When the incubation medium was deprived of calcium, the lipoperoxidative effect achieved in this experimental paradigm was still high (49% above the control), and the order of attenuation was: iron porphyrinate > S-allylcysteine > acetyl L-carnitine > dizocilpine. BAPTA-AM was effective in preventing the pro-oxidant action of both toxins, promoting even lower peroxidative levels than those quantified under basal conditions. Our results suggest that the lipid peroxidation induced in synaptosomal fractions by quinolinate plus 3-nitropropionate is largely dependent on the cytoplasmic concentrations of calcium.

Vanadium pentoxide increased PTEN and decreased SHP1 expression in NK-92MI cells, affecting PI3K-AKT-mTOR and Ras-MAPK pathways.

Vanadium is an air pollutant that imparts immunosuppressive effects on NK cell immune responses, in part, by dysregulating interleukin (IL)-2/IL-2R-mediated JAK signaling pathways and inducing apoptosis. The aim of the present study was to evaluate effects of vanadium pentoxide (V2O5) on other IL-2 receptor-mediated signaling pathways, i.e. PI3K-AKT-mTOR and Ras-MAPK. Here, IL-2-independent NK-92MI cells were exposed to different V2O5 doses for 24 h periods. Expression of PI3K, Akt, mTOR, ERK1/2, MEK1, PTEN, SHP1, BAD and phosphorylated forms, as well as caspases-3, -8, -9, BAX and BAK in/on the cells were then determined by flow cytometry. The results show that V2O5 was cytotoxic to NK cells in a dose-related manner. Exposure increased BAD and pBAD expression and decreased that of BAK and BAX, but cell death was not related to caspase activation. At 400 µM V2O5, expression of PI3K-p85 regulatory subunit increased 20% and pPI3K 50%, while that of the non-pPI3K 110α catalytic subunit decreased by 20%. At 200 µM, V2O5 showed significant decrease in non-pAkt expression (p < 0.05); the decrease in pAkt expression was significant at 100 µM. Non-pmTOR expression displayed a significant downward trend beginning at 100 µM. Expressions of pMEK-1/2 and pERK-1/2 increased substantially at 200 µM V2O5. No differences were found with non-phosphorylated ERK-1/2. PTEN expression increased significantly at 100 µM V2O5 exposure whereas pPTEN decreased by 18% at 25 µM V2O5 concentrations, but remained unchanged thereafter. Lastly, V2O5 at all doses decreased SHP1 expression and increased expression of its phosphorylated form. These results indicated a toxic effect of V2O5 on NK cells that was due in part to dysregulation of signaling pathways mediated by IL-2 via increased PTEN and decreased SHP1 expression. These results can help to explain some of the known deleterious effects of this particular form of vanadium on innate immune responses.

El endotelio sano y su disfunción en el riesgo cardiovascular / Healthy Endothelium and its Dysfunction in Cardiovascular Risk

Resumen El endotelio es una monocapa formada por células aplanadas llamadas w, que revisten la parte más interna del corazón, los vasos sanguíneos y los linfáticos. Es considerado un órgano que tiene una función de barrera, pero además se encarga de regular la permeabilidad y tono vascular, hemostasia, inflamación y angiogénesis. Esta revisión se centra sobre todo en las generalidades del endotelio vascular sano y su disfunción. Se analizan los conceptos de activación y disfunción, en donde la activación se considera como un proceso autolimitado, indispensable para la hemostasia y la inflamación. La disfunción endotelial, en cambio, es un proceso patológico, de mayor duración y que se presenta cuando el endotelio ya no puede autorregularse y cambia a un fenotipo proinflamatorio y protrombótico permanente. Esta disfunción es el primer cambio que lleva a la ateroesclerosis y al aumento del riesgo cardiovascular, por esta razón se revisan los principales biomarcadores de disfunción endotelial y riesgo cardiovascular. A medida que se avance en el conocimiento básico del endotelio y su disfunción, será posible diseñar nuevas medidas preventivas o terapéuticas que puedan disminuir dicho riesgo.

Abstract The endothelium is a monolayer of flatten cells named endothelial cells that form the inner layer of the heart, blood, and lymphatic vessels. Its function is not just as a barrier, but it is a regulator of vascular permeability and tone, hemostasis, inflammation, and angiogenesis. This review is about the general aspects of vascular endothelium and endothelial dysfunction that leads to increased vascular risk. Activation and dysfunction are discussed, considering the endothelial activation as a self-limiting process, necessary to promote inflammation and hemostasis. Endothelial dysfunction is a pathological process in which the endothelium loses its ability for self-regulation and acquires a prothrombotic and proinflammation phenotype. Endothelial dysfunction is the initial step for atherosclerosis and increased cardiovascular risk, so the main biomarkers of endothelial dysfunction are reviewed. As basic knowledge about endothelium increases, preventive or therapeutic measures can be designed as treatment or prevention the risk of its dysfunction.

Breve historia del Posgrado en Ciencias Médicas, Odontológicas y de la Salud / Brief history of the Postgraduate Program in Medical, Odontological and Health Sciences

Resumen La Universidad Nacional Autónoma de México (UNAM) es pionera en la creación de los estudios de posgrado, en específico la Facultad de Medicina tiene una extensa trayectoria en la creación y desarrollo en estos estudios. En un inicio, el objetivo se orientó propiamente a la formación de médicos especialistas, pero posteriormente enfocó su atención en el fortalecimiento académico con las actividades docentes y de investigación que proporcionan la maestría y el doctorado. Este trabajo tiene la finalidad de dar a conocer la evolución y modificaciones que los planes de estudio de maestría y doctorado han presentado a través del tiempo. Destacan las creaciones, reestructuras, adecuaciones y sobre todo la consolidación actual alcanzada con la participación multidisciplinaria de otras áreas.

Abstract The National Autonomous University of Mexico is a pioneer in the creation of postgraduate studies. Specifically, the Faculty of Medicine has an extensive trajectory in the creation and development of postgraduate studies. Initially, the objective of these studies was oriented to training of medical specialists, but later focused its attention on academic strengthening with the teaching and research activities that provided by the master's degree and doctorate. The purpose of this work is to show the evolution and modifications that the master's degree and doctorate curricula have undergone over time. It highlights the creation, restructuration, adaptations and, above all, the current consolidation achieved with the multidisciplinary participation of other areas.

Exposing the Hepatotoxicity of Medicinal Plants: A Review of Copalchi Stem Bark (Hintonia latiflora) / Exponiendo la hepatotoxicidad de las plantas medicinales: una revisión de palo amargo (Hintonia latiflora)

Resumen Se estima que el 80% de la población mundial utiliza diversas plantas medicinales para el tratamiento o control de diversas enfermedades, ya sean agudas o crónicas, debido a su accesibilidad y bajo costo, observándose en los últimos años un aumento en el consumo sin una observación médica adecuada. México es considerado como el segundo país más importante del mundo en cuanto al conocimiento de la medicina tradicional, solo después de china. El uso de las plantas medicinales se ha reportado desde tiempos prehispánicos como una opción terapéutica, sin embargo, el único enfoque que se tiene es la parte curativa y no se ha reflexionado en que las plantas poseen metabolitos secundarios (compuestos químicos producidos por las plantas con actividad biológica en los seres vivos) que, además de tener efectos terapéuticos poseen efectos tóxicos en las personas que las consumen, observándose en algunos casos efectos reversibles después de suspender su consumo. El copalchi o palo amargo es una planta medicinal que proviene de la corteza del árbol de Hintonia latiflora (sin. Coutarea latiflora), la cual ha sido utilizada principalmente como tratamiento alternativo para pacientes con diabetes tipo 2, ya que se ha demostrado que tiene efecto hipoglucemiante. Sin embargo, se han reportado casos de hepatotoxicidad aguda con un incremento en las transaminasas hepáticas (ALT y AST) por el consumo continuo de dicha corteza, no obstante el procesamiento de las plantas medicinales utilizando medios físicos (calentar o hervir) puede alterar la actividad farmacológica de los constituyentes orgánicos, los cuales pueden verse también afectados en su concentración dependiendo de los factores ambientales de cultivo, localización del suelo, humedad y temperatura ambiental, así como la temporada de cosecha (tallos, hojas, flores, raíces, semillas). El consumo de esta planta medicinal es por medio de infusiones calientes o en cápsulas con extracto.

Abstract Approximately 80% of the world's population uses various medicinal plants for the treatment or control of various diseases, whether acute or chronic, due to their accessibility and low cost, observing in recent years an increase in consumption without proper medical observation. Mexico is considered the second most important country in the world in terms of traditional medicine knowledge, only after China. The use of medicinal plants has been reported since pre-Hispanic times as a therapeutic option; however, the only focus is on the curative part and it has not been considered that plants have secondary metabolites (chemical compounds produced by plants with biological activity in living beings) that, besides having therapeutic effects, have toxic effects in people who consume them, and in some cases reversible effects are observed after suspending their consumption. Copalchi or palo amargo is a medicinal plant obtained from the bark of the Hintonia latiflora tree (syn. Coutarea latiflora), which has been used mainly as an alternative treatment for patients with type 2 diabetes, since it has been shown to have a hypoglycemic effect. However, cases of acute hepatotoxicity have been reported with an increase in hepatic transaminases (ALT and AST) by the continuous consumption of this bark. However, the processing of medicinal plants using physical means (heating or boiling) can alter the pharmacological activity of the organic constituents, which can also be affected in their concentration depending on the environmental factors of cultivation, soil location, humidity, and environmental temperature, as well as the harvesting season (stems, leaves, flowers, roots, seeds). The consumption of this medicinal plant is by means of hot infusions or in capsules with extract.

Vanadium pentoxide prevents NK-92MI cell proliferation and IFNγ secretion through sustained JAK3 phosphorylation.

Vanadium is a major air pollutant with toxic and carcinogenic effects; it also exercises immunosuppressive effects on the adaptive immune response. Its effect on the innate immune response is poorly explored. The aim of this study was to identify if vanadium pentoxide (V2O5) impairs the function of immunoregulatory NK cells and to determine possible mechanisms associated with this effect. Interleukin-2-independent NK-92MI cells were exposed to different V2O5 concentrations for 6, 12, or 24 h periods. Cell proliferation was then evaluated using CFSE staining, apoptosis by Annexin V binding, and necrosis by 7-AAD staining. The release of IL-2, -4, -6, -10, -17A, IFNγ, and TNFα by the cells were assessed using a human CBA kit. Expression of CD45, SOCS1, JAK3, pJAK3, STAT5, pSTAT5, IL-2R, IL-15R, Fas, and FasL in/on the cells was determined by flow cytometry; JAK3 and pJAK3 expression were also evaluated via confocal microscopy. The results indicated that V2O5 could inhibit NK-92MI cell proliferation and induce cell apoptosis in a dose- and time-related manner. V2O5 also inhibited IL-2, IL-10, and IFNγ secretion but mostly only after 24 h of exposure and with primarily the higher doses tested. V2O5 had no effect on expression of JAK3 and STAT5, but did cause an increase in pJAK3 and appeared to lead (trend) to reductions in levels of phosphorylated STAT5. V2O5 increased the expression of IL-2R, IL-15R, Fas, and FasL at concentrations above the 50-100 µM range. V2O5 had no effect on expression of the CD45 membrane phosphatase, but it did cause an increase in the expression of SOCS1. These results indicate that a key toxic effect of V2O5 on NK cells is a dysregulation of signaling pathways mediated by IL-2. These effects could help to explain the previously-reported deleterious effects on innate immune responses of hosts exposed to inhaled V2O5.

El aprendizaje basado en problemas como una estrategia didáctica para la educación médica / Problem-Based Learning as a Didactic Strategy for Medical Education

Resumen: La educación médica se enfrenta a nuevos retos para el desarrollo y adquisición de competencias en los estudiantes de medicina, y aunque existen diversas estrategias didácticas que pueden permitir enfrentar dichos retos, el aprendizaje basado en problemas (ABP) es una de las más eficaces para lograrlo; sin embargo, con el fin de aplicarlo de la mejor manera, es necesario entender el método y las diversas formas en que se ha implementado, así como identificar las dificultades y desventajas que se presentan. El presente artículo tiene como objetivo realizar una revisión sobre el método del ABP, sus ventajas y desventajas, así como algunos errores comunes al momento de implementarlo, haciendo hincapié en el contexto mexicano.

Abstract: Medical education faces new challenges in the development and acquisition of competencies in medical students, and although there are teaching strategies that can be helpful to reach this goal, PBL is one of the best strategies. In order to take advantage of PBL, it is important to understand the method and the various ways in which it has been implemented, as well as to identify the difficulties and disadvantages of PBL. The objective of this article is to review the PBL method, its advantages and disadvantages, and some frequent mistakes in its implementation, emphasizing the Mexican context.

El megacariocito: una célula muy original / The megakaryocyte: a very original cell

Resumen El megacariocito es la célula más grande de la médula ósea, por lo tanto es relativamente fácil reconocer su presencia al observar un aspirado o una biopsia de este tejido. Difiere de otras células por su tamaño, por ser poliploide y crecer por endomitosis. No hay otra célula humana que crezca así. Además, tiene funciones biológicas muy importantes. La más conocida es el dar origen a las plaquetas, que son indispensables para la hemostasia y la reparación de los vasos sanguíneos dañados, así como para la cicatrización de los tejidos que rodean a las heridas. Sin embargo, en los últimos años, a los megacariocitos también se les han atribuido algunas otras funciones que discutiremos en esta revisión.

Abstract The Megakaryocyte is the biggest cell in the bone marrow; therefore, it is easy to recognize in a bone marrow aspirate. In humans, this cell differs from others because of its size, its polyploidy and because it grows by endomitosis. It is the only human cell that grows this way. In addition, the megakaryocyte has very important biological functions. Its best-known function is being in charge of the production of platelets, which are essential for hemostasis, the repair of damaged blood vessels, and healing the tissues surrounding wounds. However, in recent years, other functions have been attributed to the megakaryocyte, which will be discussed in this review.