Development of undergraduate students' diagnostic accuracy for the classification of molar incisor hypomineralization.

INTRODUCTION: One of the major difficulties with respect to molar incisor hypomineralization (MIH) is its classification and differentiation from other enamel development defects (EDDs). The aim of this study was to evaluate diagnostic accuracy in dental students to classify MIH as well as its differentiation from other EDDs by combining conventional theoretical classes and e-learning-assisted pre-clinical practices. METHODS: In this one-group pre-test and post-test study, 59 second-year students assessed 115 validated photographs using the MIH Index on the Moodle learning platform. This index assesses the clinical features and extent of MIH, differentiating it from other EDDs. Students received automatic feedback after the pre-test. Two weeks later, students re-evaluated the same photographs. Both pairwise accuracy and overall diagnostic accuracy were estimated and compared for pre- and post-testing, with the area under the curve AUC, along with 95% confidence intervals (95% CI). RESULTS: The lowest diagnostic accuracy was for the ability to discriminate between white or cream-coloured demarcated opacities and hypomineralization-type defect that is not MIH. The overall pre-test accuracy was AUC = 0.83 and increased significantly post-test to AUC = 0.99 (p < .001). The overall accuracy to discriminate the extent of the lesion also increased significantly post-test (p < .001). CONCLUSION: Diagnostic skills to classify MIH can be developed by combining conventional theoretical classes and e-learning-assisted pre-clinical practices.

Developing diagnostic skills from preclinical dental education: Caries detection and assessment using e-learning assisted practice.

PURPOSE: To evaluate the feasibility of developing visual diagnostic skills for detecting and assessing dental caries using e-learning assisted practice in preclinical dental education. METHODS: A one-group before and after the study was conducted. After a theoretical lesson on cariology, 53 inexperienced second-year preclinical students assessed 78 clinical photographs using the Nyvad criteria; they received automated feedback upon completion of the test. After a week, all students reassessed the same set of photographs, which were randomly reordered. Differential diagnostic accuracy was analyzed category-pairwise, and overall accuracy measures were based on the receiver operator curve. Diagnostic accuracy in both attempts was evaluated and compared through estimation and pooling of individual student accuracies. RESULTS: Pooled category-pairwise accuracy was lower for discriminating Sound surface from Non-cavitated-active caries, and for discriminating inactive caries (surface discontinuity) from intact surface inactive caries and Cavitated-active caries. Pooled overall accuracy, after the theoretical lesson, was 0.79 (95% confidence interval [CI] 0.77-0.81), and it increased to 0.99 (95% CI 0.98-0.99) after feedback. Between-student variability in accuracy was reduced from I2  = 0.66 to 0.55. CONCLUSION: E-learning assisted practice is a feasible alternative to start developing visual diagnostic skills for detecting and assessing dental caries using the Nyvad criteria from preclinical dental education in cariology. However, further studies are required to evaluate its effectiveness in improving real-world practice knowledge and skills.

Impact of the undergraduate clinical teaching-learning process on caries detection and treatment decision-making

Aim: The aim of this study was to evaluate caries diagnosis and treatment decisions made by undergraduate dental students based on ICDAS or Nyvad criteria. Methods: Twelve students analyzed 90 digital photographs of permanent teeth at different clinical stages of carious lesion development and chose among different treatments in three different assessments: when there was no knowledge of the criteria (described as "No knowledge (N)"; when there was theoretical knowledge of the criteria (described as "Theoretical knowledge (T)" and when there was theoretical knowledge, clinical experience about dental caries and the criteria (described as "Theoretical and clinical knowledge (TC)". For "T" and "TC" the students were randomized into two experimental groups ­ ICDAS or Nyvad (experimental units: 6 students/group). The reference standard was established cooperatively by two experienced researchers. Criteria performance was evaluated by sensitivity, specificity, AUC, and Kappa statistics. Treatment decision was described in percentage by contingency tables and Spearman's correlation with the reference standard. Results: The first assessment demonstrated a high percentage of operative treatment even for initial enamel lesions based on ICDAS criteria and treatment was proposed for both active and inactive lesions, according to the Nyvad criteria. In the second assessment, the students continued recommending treatments for initial or inactive lesions, but less frequently. In the third assessment, treatment decisions presented greater cohesion in relation to the assigned classification criterion. The criteria presented no differences between them in terms of diagnostic in the third assessment. Conclusion: Clinical experience may improve caries detection and treatment decisions with the use of ICDAS and Nyvad criteria

Estructura factorial y confiabilidad de una escala de autoeficacia académica en estudiantes chilenos de Fonoaudiología / Factorial structure and reliability of an academic self-efficacy scale in Chilean Phonoaudiology students

Introducción: las expectativas de autoeficacia son un predictor importante del éxito académico en todos los niveles formativos, incluyendo las carreras de la salud. El diagnóstico temprano de los niveles de autoeficacia de los alumnos y una oportuna intervención puede ser una estrategia útil para favorecer los procesos formativos. Esto hace necesario contar con instrumentos psicométricamente adecuados que permitan su evaluación en los estudiantes. Objetivo: evaluar la estructura factorial y la consistencia interna de la Escala de Autoeficacia Percibida Específica de Situaciones Académicas de Palenzuela en estudiantes de Fonoaudiología de Chile. Métodos: esta escala se aplicó a 282 estudiantes elegidos por muestreo no probabilístico por cuotas.Se realizó un análisis factorial exploratorio y se evaluó la confiabilidad con alfa de Cronbach. Resultados: presentaban entre 19 y 33 años de edad y 84,59 % eran mujeres. Se identificó una estructura unifactorial. Su consistencia interna fue adecuada según un alfa de Cronbach de 0,87. Conclusiones: existe evidencia psicométrica de la validez de constructo de la escala como medida unifactorial de autoeficacia académica en estudiantes de Fonoaudiología de Chile; además, muestra una adecuada confiabilidad(AU)

Introduction: Self-efficacy expectations are an important predictor for academic success at all levels of education, including the health-related majors. Early diagnosis of students' self-efficacy levels and timely intervention can be a useful strategy to favor the training processes. This makes it necessary to have psychometrically adequate instruments that allow students to evaluate themselves. Objective: To evaluate the factorial structure and internal consistency of the Scale of Specific Perceived Self-efficacy of Academic Situations of Palenzuela in Phonoaudiology students in Chile. Methods: This scale was applied to 282 students chosen by non-probabilistic sampling by rates. They were at ages between 19 and 33 years and 84.59% were women. An exploratory factorial analysis was performed and reliability was evaluated with Cronbach's alpha. Results: A unifactorial structure was identified. Its internal consistency was adequate according to Cronbach alpha of 0.87. Conclusions: There is psychometric evidence on the validity of the scale construction as a unifactorial measure of academic self-efficacy in Phonoaudiology students in Chile. In addition, it shows an adequate reliability(AU)

Examiner's experience and the outcome interpretation of ICDAS and Nyvad's system - a prospective in vitro study.

OBJECTIVE: To evaluate, prospectively, the influence of examiner's experience in interpreting and applying the caries detection systems ICDAS (IC) and Nyvad (NY). MATERIAL AND METHODS: Twelve second-year undergraduate dental students (UG) and 12 postgraduates (PG) MSc level analysed and codified 77 clinical dental caries photographs at three different moments: initially, without any training; after one week of receiving training through a theoretical class; and after two years. Reproducibility and correlation was evaluated; sensitivity, specificity and area under ROC curve (AUC) were dichotomized according to the presence of cavitation (IC) and in relation to disease activity (NY). RESULTS: IC presented good kappa values for the first two evaluations. Both criteria resulted in good Spearman's correlation after two years (IC = UG: 0.89; PG: 0.93/NY = UG: 0.81; PG: 0.82). Sensitivity, specificity and AUC were statistically higher in the third evaluation by UG for Nyvad. CONCLUSIONS: ICDAS criteria seem to be instinctively understood by students without clinical experience. Nyvad's concepts performed better after two years where the students deepened their theoretical knowledge and experienced clinical practice, collaborating with the identification of activity signs.

Factores de riesgos prevalentes en pacientes ingresados por enfermedad cerebrovascular / Prevailing risk factors in hospitalized patients with cerebrovascular disease

Introducción: la enfermedad cerebrovascular en la actualidad es uno de los problemas de salud más importantes, no solo en Cuba, sino en los países desarrollados del mundo. Ocupa el segundo lugar como causa de discapacidad permanente en el adulto y muerte, solo es superada por las enfermedades cardiovasculares y el cáncer, lo que determina su relevancia médica, económica y social por el costo en la rehabilitación y los cuidados que requieren los pacientes con importantes daños neurológicos. Objetivo: caracterizar los factores de riesgos prevalecientes en los pacientes ingresados por enfermedad cerebrovascular. Métodos: estudio descriptivo y longitudinal en una muestra de 144 pacientes ingresados por enfermedad cerebrovascular en el servicio de urgencias del Hospital Clinicoquirúrgico Docente Dr. Octavio de la Concepción y de la Pedraja entre enero y diciembre de 2012. Se aplicó una encuesta que exploró diferentes variables y los datos obtenidos se codificaron manualmente. Resultados: el tipo de enfermedad cerebrovascular que prevaleció fue la hemorragia subaracnoidea, seguida por la hemorragia cerebral. Los factores de riesgo modificables que se identificaron con mayor frecuencia fueron la hipertensión arterial y la diabetes mellitus. Se constató insuficiente control de los factores de riesgo en la atención primaria de salud. Conclusiones: los factores de riesgo mayormente asociados a la enfermedad cerebrovascular fueron la hipertensión arterial y la edad avanzada, seguidos por el tabaquismo y la diabetes mellitus, en correspondencia con un control deficiente de estas enfermedades(AU)

Introduction: cerebrovascular diseases are presently one of the most important health problems not only in Cuba but in the developed countries as well. It holds the second place in the list of causes of permanent disability and of death in adults, just preceded by cancer and cardiovascular diseases, which determines its medical, economic and social relevance due to the cost of rehabilitation and of care that patients having significant neurological damage require. Objective: to characterize the prevailing risk factors in hospitalized patients with cerebrovascular disease. Methods: longitudinal and descriptive study of a sample of 144 patients with cerebrovascular disease, who were admitted to the emergency service of "Dr Octavio de la Concepcion y de la Pedraja" teaching, clinical and surgical hospital from January through December, 2012. A survey was conducted to explore different variables and the collected data were manually coded. Results: the predominant type of cerebrovascular disease was subararachnoid hemorrhage followed by brain hemorrhage. The most frequently modifiable risk factors were blood hypertension and diabetes mellitus. It was observed that the control of risk factors was poor at the primary health care setting. Conclusions: the risk factors mainly associated to cerebrovascular disease were blood hypertension and advanced age, followed by tabaquismo and diabetes mellitus, in correspondence with a deficient control of these illnesses(AU)

Factores de riesgos prevalentes en pacientes ingresados por enfermedad cerebrovascular / Prevailing risk factors in hospitalized patients with cerebrovascular disease

INTRODUCCIÓN: la enfermedad cerebrovascular en la actualidad es uno de los problemas de salud más importantes, no solo en Cuba, sino en los países desarrollados del mundo. Ocupa el segundo lugar como causa de discapacidad permanente en el adulto y muerte, solo es superada por las enfermedades cardiovasculares y el cáncer, lo que determina su relevancia médica, económica y social por el costo en la rehabilitación y los cuidados que requieren los pacientes con importantes daños neurológicos. OBJETIVO: caracterizar los factores de riesgos prevalecientes en los pacientes ingresados por enfermedad cerebrovascular. MÉTODOS: estudio descriptivo y longitudinal en una muestra de 144 pacientes ingresados por enfermedad cerebrovascular en el servicio de urgencias del Hospital Clinicoquirúrgico Docente "Dr. Octavio de la Concepción y de la Pedraja" entre enero y diciembre de 2012. Se aplicó una encuesta que exploró diferentes variables y los datos obtenidos se codificaron manualmente. RESULTADOS: el tipo de enfermedad cerebrovascular que prevaleció fue la hemorragia subaracnoidea, seguida por la hemorragia cerebral. Los factores de riesgo modificables que se identificaron con mayor frecuencia fueron la hipertensión arterial y la diabetes mellitus. Se constató insuficiente control de los factores de riesgo en la atención primaria de salud. CONCLUSIONES: los factores de riesgo mayormente asociados a la enfermedad cerebrovascular fueron la hipertensión arterial y la edad avanzada, seguidos por el tabaquismo y la diabetes mellitus, en correspondencia con un control deficiente de estas enfermedades.

INTRODUCTION: cerebrovascular diseases are presently one of the most important health problems not only in Cuba but in the developed countries as well. It holds the second place in the list of causes of permanent disability and of death in adults, just preceded by cancer and cardiovascular diseases, which determines its medical, economic and social relevance due to the cost of rehabilitation and of care that patients having significant neurological damage require. OBJECTIVE: to characterize the prevailing risk factors in hospitalized patients with cerebrovascular disease. METHODS: longitudinal and descriptive study of a sample of 144 patients with cerebrovascular disease, who were admitted to the emergency service of "Dr Octavio de la Concepcion y de la Pedraja" teaching, clinical and surgical hospital from January through December, 2012. A survey was conducted to explore different variables and the collected data were manually coded. RESULTS: the predominant type of cerebrovascular disease was subararachnoid hemorrhage followed by brain hemorrhage. The most frequently modifiable risk factors were blood hypertension and diabetes mellitus. It was observed that the control of risk factors was poor at the primary health care setting. CONCLUSIONS: the risk factors mainly associated to cerebrovascular disease were blood hypertension and advanced age, followed by tabaquismo and diabetes mellitus, in correspondence with a deficient control of these illnesses.

La enseñanza de la cariología en la Facultad de Odontología de la Universidad CES, Medellín, Colombia / Teaching of Cariology at the College of Dentistry, Universidad CES, Medellin, Colombia

El propósito del presente artículo es disertar sobre el problema de la formación del estudiante de odontología, la cual debería ser integral-integradora, orientada a crear un concepto unificado en la mente del futuro profesional, donde todas las enfermedades que tienen origen en relación con la bio-película dental puedan ser analizadas y comprendidas como distintas manifestaciones en cuya etiología existen factores comunes que permiten definirlas como enfermedades multifactoriales, complejas, con un importante componente social. En este artículo se presenta la experiencia de más de treinta años, de la Universidad CES, en la enseñanza de las enfermedades de origen dento-bacteriano, caries dental y enfermedades del periodonto, haciendo un comparativo con las propuestas de la enseñanza de la cariología por competencias desarrollada en la comunidad europea y que se ha propuesto en Colombia.

The purpose of this article is to discuss in detail the problems related to teaching dental students, in a holistic manner oriented at developing a unified concept of diseases of dento-bacterial origin in order to properly analyze and understand dental caries and periodontal diseases, both sharing etiological factors which allow clinicians and researchers to define them as a complex, multifactorial disease with a very strong social component. In this article, the authors present thirty years of experience at the College of Dentistry, Universidad CES, Medellin, teaching dental caries and periodontal diseases in a comprehensive manner, comparing their methodology with the model proposed by the European Community and the ACFF (Alliance for a caries free future) in Colombia, based on the development of competences.

Glial activation in a pilocarpine rat model for epileptogenesis: a morphometric and quantitative analysis.

In this work we examined the correlation between long-term glial resilience and slow epileptogenesis using the pilocarpine-insult rat model. We assessed, quantitatively and morphometrically, glial fibrillary acidic protein (GFAP) expression and cell densities in hippocampus in a dose-response manner 2, 4 and 8 weeks after the pilocarpine insult. GFAP changes were correlated with observations on microglial activation. We used a commonly applied epileptogenic pilocarpine dose (380mg/kg) and its fractions of 1/10, 1/4 and 1/2. GFAP expression evaluated at 2 weeks revealed dose-dependent cytoskeletal hypertrophy and loss of GFAP+ cell densities in hippocampus. At 4-week timepoint, recoveries of the above mentioned parameters were observed in all groups, except for the full dose group in which the astrocytic hypertrophy reached the highest level, while its density dropped to the lowest level. Strong and localized microgliosis revealed by CD11b immunoreactivity was observed in hilus in the full dose group at 2- and 4-, persisting at 8-week timepoints. Through changing pattern analysis, we conclude that the loss of astroglial resilience is likely to be a determining factor for spontaneous recurrent seizure onset.

Reduction of serotonergic neurons in the dorsal raphe due to chronic prenatal administration of a tryptophan-free diet.

Serotonin (5-HT) is a widely studied neurotransmitter which plays an important role in the development and proper functioning of the organism throughout life. The appearance of 5-HT system early in ontogeny suggests the hypothesis that 5-HT plays a regulatory role in neurodevelopment. This study investigated the effect of administration of a tryptophan deficient diet during prenatal development on the morphology and cell population of the dorsal raphe. The experimental diet, containing balanced amounts of carbohydrates, lipids and proteins, was provided to a time-mated group of rats from gestational day 5 until delivery. Control groups were fed with (i) the experimental diet formulation with 0.2% tryptophan added to the mixture, or (ii) a regular chow diet. At delivery, five pups per dam were euthanized. Body and brain weight was measured and brain sections were processed for immunohistochemistry for tryptophan hydroxylase (TrpH) and whole brain 5-HT analysis. Sections containing dorsal raphe were photographed with a light microscope and TrpH positive neurons quantified. Brain weights in the tryptophan deprived group showed no difference as compared with controls while body weights were reduced by 25%. Total numbers of serotonergic neurons at the dorsal raphe in the prenatal tryptophan deficient pups were reduced by 35%. A regional analysis of the dorsal raphe indicated a marked cellular reduction in the medial and caudal sections of the nucleus, which contains the majority of serotonergic neurons, in the tryptophan deprived condition. Quantitative 5-HT analysis showed that the brain concentration was similar among conditions. In conclusion, gestational tryptophan deprivation exerts adverse effects on the development of the 5-HT system, particularly in the dorsal raphe, manifested by decreased numbers of serotonergic neurons as well as altered topography in this important nucleus.

Brief report: life history and neuropathology of a gifted man with Asperger syndrome.

Despite recent interest in the pathogenesis of the autism spectrum disorders (pervasive developmental disorders), neuropathological descriptions of brains of individuals with well documented clinical information and without potentially confounding symptomatology are exceptionally rare. Asperger syndrome differs from classic autism by lack of cognitive impairment or delay in expressive language acquisition. We examined the 1,570 g brain of a 63 year old otherwise healthy mathematician with an Autistic Spectrum Disorder of Asperger subtype. Except for an atypical gyral pattern and megalencephaly, we detected no specific neuropathologic abnormality. Taken together, the behavioral data and pathological findings in this case are compatible with an early neurodevelopmental process affecting multiple neuroanatomic networks, but without a convincing morphologic signature detectable with routine neuropathologic technology.

Increased transvascular transport of WGA-peroxidase after chronic perinatal stress in the hippocampal microvasculature of the rat.

Brain endothelial ultrastructural properties contribute to maintain proper blood-brain barrier (BBB) function. Several physiological and pathological conditions have been shown to alter BBB permeability to blood-borne molecules, acute and chronic stress among them. In the rat, early life stress increased transvascular transport of Evans blue, however, the route of tracer extravasation is not fully known; therefore the aim of the present experiment was to describe the ultrastructural changes in endothelial cells subsequent to chronic perinatal stress in order to ascertain the route for transvascular transport of an electrodense tracer. Pregnant Wistar rats and their litters were used. Four pregnant rats were subjected to forced swimming between gestational days 10 to 20. After delivery, half of the control litters underwent 180 min maternal separation from postnatal day 2 to 20. Controls were kept free of any stress manipulation. At sacrifice between postnatal days 1 to 30 subjects were given intracardially the lectin wheat germ agglutinin conjugated to horseradish peroxidase (WGA-HRP). WGA-HRP stained hippocampi were processed for ultrastructural analysis, transmission electron micrographs were obtained and endothelial ultrastructural parameters quantified using the ImageJ software. Both stress procedures accelerated gross microvessel development by decreasing capillary wall thickness and endothelial microvilli. However, early-life stress also neutralized endothelial glycocalyx, increased vesicle-mediated transport and tended to promote the formation of secondary lysosomes containing endocytosed WGA-HRP vesicles, all parameters of altered endothelial cell function. Tight junction development in both stress groups was similar to the control pups.

Normal neuronal migration / Migración neural normal

Ontogenesis of both central and peripheral nervous systems depends on basic, molecular and cellular mechanisms of the normal neuronal migration. Any deviation leads to neural malformations. All neural cells and structures derive from the neural ectoderm, which under the influence of the notochord and the molecules Noggin and Chordin, is transformed consecutively into neural plate, neural groove, neural tube and primary vesicles. Of the latter, the most rostral, the prosencephalon, two vesicles are bilaterally generated, the telencephalon and in the middle, the unpaired diencephalons. The telencepahlic vesicles generate the cerebral hemispheres and the lateral ventricles; the latter constitutes the main source of progenitor neuroepithelial cells (NEC) in the subventricular zone. The NEC massively migrates to constitute the cerebral cortex and other hemispheric structures in the telencephalon and diencephalon. The NEC expresses a broad repertory of markers: BLBP, GLAST, vimentin, tenascin, S100-3 and, in primates GFAP; in a sequential order the NEC form the first cortical layer formed by the marginal zone and the subplate. The marginal zone harbors the Cajal-Retzius reelin positive neurons and reelin negative neurons. Reelin, besides signaling stop to migrating neurons, also participates in ordering the cortical layers; it is known that in mutant mice lacking reelin cortical layers are disrupted. Genetic studies indicate that ApoER2, Vldr (both reelin receptors) and Dab1, reelin signaling adaptor protein, enter into a common pathway leading Dab1 to phosphorylation in migrating neurons. Cortical pyramidal neurons generate at germinal zone; interneurons generate both in Vz and SVZ in medial ganglionic eminence and caudal GE. Two types of neuronal migration coexist, radial and tangential. In radial migration, the neurons move perpendicular to marginal zone and radial glia serves as a scaffold to migrating cells; in the tangential way, neurons migrate in parallel to brain surface guided by semaphorins, neuropilins, cell adhesion molecules, neuregulins, chemokines and the slit and robo families of attractant and repellent molecules. The migratory cycle of neurons involves leading process dynamics and somal translocation, which involves the movement of perinuclear material, organelles and nucleus. Leading process stability depends on the microtubular array that links the leading edge of the cell with the soma. The centrosome is a microtubule center to control microtubule polymerization. In radially migrating neurons, the centrosome establishes a link between centrioles and nuclear membrane. The effective neuronal migration is only completed by translocation of the cell soma, which occurs with cytoplasmic dilatation, and then the centrosome and Golgi apparatus approach it, finally nucleus advances to the cytoplasmic dilatation. Movement of centrosome and nucleus depends on integrity of a microtubule network. Most of the microtubules surrounding the nucleus are tyrosinated, making them dynamic; microtubules at the anterior pole of the nucleus, near the centrosome, are acetylated. Once neurons reach their final destination, they need to cancel the migratory program and differentiate. The mechanisms are unknown; possibly early patterns of activity in the target region could influence. Ca2+ influx is a proposed mechanism for halting migration.

La ontogenia de los Sistemas Nervioso Central y Nervioso Periférico depende de procesos como la proliferación, diferenciación y migración neuronal, entre otros. Cualquier desviación resulta en malformaciones. Las estructuras y células nerviosas derivan del ectodermo, la notocorda induce la formación de la placa neural mediante la secreción de las moléculas Noggin y Chordin; posteriormente la placa neural se convierte en surco y tubo neurales. Una vez que el tubo neural está formado, las células neuroepiteliales (CNE), futuras neuronas y glía, en la zona subventricular migran masivamente para constituir la corteza cerebral y otras estructuras. Las CNE, al ser células gliales, expresan múltples marcadores: BLBP, GLAST, vimentin, tenascin, S1 00p y en primates GFAP Las CNE forman la primera capa cortical, también llamada preplato. Las siguientes divisiones celulares darán origen a la zona marginal y al subplato. Las subsecuentes neuronas que arriban al subplato desplazan a las anteriores de modo que en las capas superficiales se encuentran las últimas neuronas que llegaron. La capa marginal o capa I contiene células de Cajal-Retzius inmunorreactivas a reelin y neuronas reelin-negativas situadas más profundamente. La proteína reelin, además de servir como señal de alto a las neuronas migratorias, también interviene en el orden de la laminación cortical, la cual es desordenada en los ratones que carecen de reelin. No se conoce en su totalidad el mecanismo molecular mediante el cual reelin regula los procesos antes mencionados. Hasta el momento se conoce que ApoER2, Vldlr (ambos receptors de reelin) y Dab1, proteína adaptadora en la señalización por reelin, participan en una vía común que lleva a la fosforilación de Dab1 en las neuronas en migración. Las neuronas piramidales corticales se generan en el telencéfalo dorsal, mientras que las interneuronas se generan en la zona y subzona ventriculares del telencéfalo ventral, en las bien definidas subdivisiones de la eminencia gangliónica (EG): lateral, medial y caudal. La migración neuronal puede ser radial o tangencial; la migración radial emplea a la glía radial mientras que en la tangencial las neuronas migran paralelamente a la superficie cortical. En los dos tipos hay formación de neuritas, translocación somática y núcleocinesis. Varios factores participan en la migración tangencial: semaforinas, neuropilinas, moléculas de adhesion celular, neuregulinas, quimiocinas y moléculas atrayentes y repelentes de las familias slit y robo. El ciclo migratorio de las neuronas incluye la translocación del soma con movilización de material perinuclear, organelos y del núcleo. Así mismo, dicho ciclo aparece con morfología bien definida en una variedad de neuronas lo que refleja adaptación a ambientes específicos. De tal modo que las claves guías influyen en la frecuencia y orientación de la emergencia dendrítica, que a su vez permite a las neuronas migrantes cambiar de dirección sin reorientar las dendritas preexistentes. La estabilidad del mecanismo depende de la organización microtubular que asocia el borde celular con el soma; ya que el sistema de microtúbulos apoya dicho mecanismo y también permite el flujo de vesículas. En las células animales el centrosoma es el centro que organiza el citoesqueleto, la polimerización, el arreglo de los microtúbulos perinucleares y establece el contacto de los centriolos con la membrana nuclear. En la migración radial el movimiento hacia delante de los centriolos deforma el conjunto perinuclear de microtúbulos. Se debe a la elasticidad de ese conjunto microtubular y sus proteínas motoras asociadas al desplazamiento del núcleo. La nucleocinesis o movimiento del núcleo determina la dirección del movimiento nuclear, la migración neuronal efectiva sólo se completa por la translocación subsecuente del soma, lo cual ocurre por la dilatación del citoplasma y el movimiento del centrosoma y del aparato de Golgi hacía el mecanismo; finalmente el núcleo avanza e invade la dilatación del citoplasma. El movimiento del centrosoma y del núcleo depende de la integridad de la red microtubular y de las modificaciones posttranscripción. La mayoría de los micotúbulos perinucleares están tirosinados, lo cual los hace extremadamente dinámicos; en cambio, los microtúbulos del polo anterior del núcleo, vecinos del centrosoma, están acetilados y por ende más estables. Se ha dicho que los microtúbulos perinucleares se hallan conectados con el centrosoma que en sí es el centro que los organiza. Además, se han descrito otras proteínas asociadas con la polaridad celular que desempeñan un papel esencial en la coordinación del movimiento del centrosoma y del núcleo en cada ciclo migratorio. Finalmente, una vez que las neuronas alcanzan su posición definitiva, requieren cancelar el programa migratorio y continuar su diferenciación hasta alcanzar las características morfológicas y funcionales que les corresponden.

Clinical heterogeneity of human neurocysticercosis results from complex interactions among parasite, host and environmental factors.

Human neurocysticercosis (NC) is endemic in most countries of Latin America, Asia and Africa and is re-emerging in some industrialized nations. Both within and among endemic countries, NC is very variable in its clinical and radiological features, as well as in the intensity of the immuno-inflammatory reactions of the hosts. This review, focusing on the Mexican experience, describes and interprets the heterogeneity of NC as the result of different combinations among factors associated with the parasite, host and environment. The review may serve to foster similar descriptive efforts in other endemic areas of the world in order to facilitate the identification of the distinct factors that participate in the complex pathogenesis and diverse clinical outcomes of NC. In particular, it is necessary to understand the precise physiopathology of the inflammatory reaction associated with NC, as inflammation is one of the characteristics of those NC cases that are clinically more severe and less responsive to current treatments. Devising new medical interventions through the use of molecular regulators of the innate and adaptive immune responses of the host is a largely unexplored approach that could improve the existing forms of treatment.

Prenatal stress alters microglial development and distribution in postnatal rat brain.

Stress affects microglial function and viability during adulthood and early postnatal life; however, it is unknown whether stress to the pregnant dam might alter offspring microglia. The effects of prenatal stress on microglial development and distribution in the postnatal brain were studied using Wistar rats. Prenatal stress consisting of 20 min of forced swimming occurred on embryonic days 10-20. On postnatal days 1 and 10, stressed and control pups were killed. Microglia were identified using Griffonia simplicifolia lectin and quantified in the whole encephalon. In addition, plasma corticosterone was measured in dams at embryonic day 20, and in pups on postnatal days 1 and 10. At postnatal day 1, there was an increase in number of ramified microglia in the parietal, entorhinal and frontal cortices, septum, basal ganglia, thalamus, medulla oblongata and internal capsule in the stressed pups as compared to controls, but also there was a reduction of amoeboid microglia and the total number of microglia in the corpus callosum. By postnatal day 10, there were no differences in the morphologic type or the distribution of microglia between the prenatal stress and control groups, except in the corpus callosum; where prenatal stress decreased the number of ramified microglia. The stress procedure was effective in producing plasma rise in corticosterone levels of pregnant rats at embryonic day 20 when compared to same age controls. Prenatal stress reduced the number of immature microglia and promoted an accelerated microglial differentiation into a ramified form. These findings may be related to an increase in plasma corticosterone in the pregnant dam.

Dietary tryptophan restriction in rats triggers astrocyte cytoskeletal hypertrophy in hippocampus and amygdala.

We have previously reported that dietary tryptophan (TRP) restriction in a rat crucial postnatal developmental stage induces depression-like behavior and alters dendritic spine density in CA1 pyramidal neurons and granule cells of the hippocampus. Due to astrocyte involvement in critical brain mechanisms, it seems worth to investigate possible adaptive changes in the glial population with TRP restriction. Experimental rats were fed with low TRP diet (20% of TRP level of the laboratory rat chow) from postnatal days 30-60. Antibody against glial fibrillary acidic protein (GFAP), a principal intermediate filament in astrocytes, was used to evaluate cytoskeletal hypertrophy and glial proliferation. Our results showed an increase in size and branching of GFAP-immunoreactive (IR) cells in the dorsal hippocampus and amygdala, characteristics of an astrocytic activation. No significant differences were found regarding the number of GFAP-IR cells in both regions. These results indicate that dietary TRP restriction can induce astrocytic activation, hence, provide further evidences supporting the hypothesis that serotonin may also modulate glial morphology.