Rab Proteins and the Secretory Pathway: The Case of Rab18 in Neuroendocrine Cells

The secretory pathway is a process characteristic of cells specialized in secretion such as endocrine cells and neurons. It consists of different stages that are dependent on specific transport of proteins in vesicular-tubular carriers. Biochemical analyses have unveiled a number of protein families that confer identity to carrier vesicles and specificity to their transport. Among them is the family of Rab proteins, Ras-like small GTPases that anchor to the surface of transport vesicles and participate in vesicle formation from the donor compartment, transport along cytoskeletal tracks, and docking and fusion with the acceptor compartment. All of these functions are accomplished through the recruitment of effector proteins, such as sorting adaptors, tethering factors, kinases, phosphatases, and motors. The numerous Rab proteins have distinct subcellular distributions throughout the endomembrane system, which ensures efficient cargo transfer. Rab proteins act as molecular switches that alternate between a cytosolic GDP-bound, inactive form and a membrane-associated GTP-bound, active conformation. Cycling between inactive and active states is a highly regulated process that enables Rabs to confer spatio-temporal precision to the different stages through which a vesicle passes during its lifespan. This review focuses on our current knowledge on Rab functioning, from their structural features to the multiple regulatory proteins and effectors that control Rab activity and translate Rab function. Furthermore, we also summarize the information available on a particular Rab protein, Rab18, which has been linked to the control of secretory granule traffic in neuroendocrine cells

Semi-synthetic Derivatives of Limonin A: Synthesis Using Basic Hydrolysis and Reduction with NaBH4

Limonin A (L-A) was obtained from seeds of Citrus sinensis that were dried, grounded, and extracted using Soxhlet equipment. Initially, 100% hexane was used to eliminate fats, and finally, 100% dichloromethane was used in order to concentrate and isolate the compound. L-A recrystallization was performed using acetic acid. The purified fraction was identified as limonin according to spectral nuclear magnetic resonance (NMR) data. Two reactions were performed from L-A: Basic hydrolysis that acted on the A’ lactone ring producing a sodium salt of the lactone, and reduction with NaBH4 to reduce the carbonyl of carbon C-7 and generate the corresponding alcohol limonol. The structural modification of abundant secondary metabolites can become a source of new products with biological activity, useful in the pharmaceutical, cosmetic, and agrochemical industries of natural origin. Keywords: limonin, semisynthetic derivates, bioactive compounds, non-timber forest products. Resumen La limonina A (L-A) se obtuvo a partir de semillas de Citrus sinensis, que fueron secadas, molidas y extraídas en equipo Soxhlet, utilizando inicialmente hexano al 100% para eliminar grasas y finalmente diclorometano al 100% para concentrar y aislar el compuesto. La re cristalización de la L-A se realizó utilizando ácido acético. La fracción purificada se identificó como limonina, acorde a los datos espectrales de RMN (Resonancia Magnética Nuclear). A partir de la Limonina A se realizaron dos reacciones: Hidrólisis básica que actuó sobre el anillo de lactona A’ produciendo la sal sódica de lactona y reducción con NaBH4 para reducir el carbonilo del carbono C-7 y generar el correspondiente alcohol limonol. La modificación estructural de metabolitos secundarios abundantes puede convertirse en una fuente para generar nuevos productos con actividad biológica, útiles en las industrias farmacéutica, cosmética y agroquímica de origen natural. Palabras Clave: Limonina; derivados semisintéticos, compuestos bioactivos, productos forestales no maderables

Diferencias cinemáticas entre el revés a una y dos manos de tenis usando giróscopos. Un estudio exploratorio

The main objective of this article is to compare angular kinematics and intersegmental coordination of the upper limbs between one-handed and two handed backhands in a sample of 20 male competition players by using gyroscopes and compare ball speeds and accuracy obtained in both types of backhands. The angular kinematics, intersegmental coordination, ball speed and accuracy were compared during a specific stroke performance test using four inertial sensors (trunk, head, arm and forearm). We hypothesize that there will be significant differences in terms of ωpeak and intersegmental coordination in some of the segments measured between DH and SH by using gyroscopes, but the opposite will happen in the variables speed ball and accuracy. There are no significant differences between one-handed backhand and two-handed backhand in terms of speed and accuracy. Higher peaks angular speeds were found in the trunk and arm over the x axis in two-handed backhand which could indicate that this type of backhand generates greater trunk rotation and external rotation of the arm and forearm compared to one-handed backhand. The peak angular speeds were greater in the arm and forearm on the z axis in the case of one-handed backhand which is related to a greater extension of the forearm accompanied by a higher termination in the technical gesture. In conclusion, the proposed model of biomechanical analysis through the use of gyroscopes is especially useful for kinematic analysis of tennis strokes during field-based experimentation and could easily be adapted to other sports. It is also a low-cost and portable alternative that includes all instrumentation and data processing.El objetivo principal del presente estudio es comparar la cinemática angular y la coordinación intersegmentaria del tren superior entre el revés a una y dos manos de tenis en una muestra de 20 jugadores de nivel competición mediante el uso de giróscopos, y comparar las velocidades de pelota y la precisión obtenidas en ambos tipos de revés. La cinemática angular, la coordinación intersegmentaria, la velocidad de pelota y la precisión se obtuvieron de cada jugador mediante una prueba de golpeo realizada con cuatro sensores inerciales colocados (tronco, cabeza, brazo y antebrazo). Se sostiene la hipótesis de que se encontraran diferencias significativas en términos de ωpico y coordinación intersegmentaria en alguno de los segmentos intervinientes en el revés a una y dos manos, pero sucederá lo contrario en las variables velocidad de pelota y precisión. Tras el análisis de los resultados, no se encontraron diferencias significativas entre el revés a una y dos manos en velocidad de pelota y precisión. Sin embargo, se encontraron velocidades angulares pico significativamente más altas en el tronco y brazo sobre el eje x en el revés a dos manos, lo que podría indicar que este tipo de revés genera una rotación de tronco y una rotación externa de brazo y antebrazo mayores que las del revés a una mano. Las velocidades angulares pico fueron significativamente mayores en el brazo y antebrazo sobre el eje z en el caso del revés a una mano, lo cual está relacionado con una mayor extensión del antebrazo acompañada de una terminación más alta del gesto técnico. En conclusión, el modelo propuesto de análisis biomecánico a través del uso de giróscopos es especialmente útil para el análisis cinemático de los golpes de tenis en estudios de campo y podría adaptarse fácilmente a otros deportes, suponiendo una alternativa portable y de bajo coste que además incluye toda la instrumentación y procesamiento de los datos

Formal Hecke algebras and algebraic oriented cohomology theories

In the present paper we generalize the construction of the nil Hecke ring of Kostant-Kumar to the context of an arbitrary algebraic oriented cohomology theory of Levine-Morel and Panin-Smirnov, e.g. to Chow groups, Grothendieck's K_0, connective K-theory, elliptic cohomology, and algebraic cobordism. The resulting object, which we call a formal (affine) Demazure algebra, is parameterized by a one-dimensional commutative formal group law and has the following important property: specialization to the additive and multiplicative periodic formal group laws yields completions of the nil Hecke and the 0-Hecke rings respectively. We also introduce a deformed version of the formal (affine) Demazure algebra, which we call a formal (affine) Hecke algebra. We show that the specialization of the formal (affine) Hecke algebra to the additive and multiplicative periodic formal group laws gives completions of the degenerate (affine) Hecke algebra and the usual (affine) Hecke algebra respectively. We show that all formal affine Demazure algebras (and all formal affine Hecke algebras) become isomorphic over certain coefficient rings, proving an analogue of a result of Lusztig.Comment: 28 pages. v2: Some results strengthened and references added. v3: Minor corrections, section numbering changed to match published version. v4: Sign errors in Proposition 6.8(d) corrected. This version incorporates an erratum to the published versio

Interrelation of adipose tissue macrophages and fibrosis in obesity

Obesity is characterized by adipose tissue expansion, extracellular matrix remodelling and unresolved inflammation that contribute to insulin resistance and fibrosis. Adipose tissue macrophages represent the most abundant class of immune cells in adipose tissue inflammation and could be key mediators of adipocyte dysfunction and fibrosis in obesity. Although macrophage activation states are classically defined by the M1/M2 polarization nomenclature, novel studies have revealed a more complex range of macrophage phenotypes in response to external condition or the surrounding microenvironment. Here, we discuss the plasticity of adipose tissue macrophages (ATMs) in response to their microenvironment in obesity, with special focus on macrophage infiltration and polarization, and their contribution to adipose tissue fibrosis. A better understanding of the role of ATMs as regulators of adipose tissue remodelling may provide novel therapeutic strategies against obesity and associated metabolic diseases

Relationship between weight status and aerobic capacity in school children in Tijuana, Mexico

INTRODUCTION: Overweight and obesity in children can deteriorate physical and psychological health in the short, mid, and long term; alterations like dyslipidemia, hyperinsulinemia, glucose intolerance and other cardiovascular risk factors like prehypertension and hypertension occur more frequently in children and teens with obesity. PURPOSE: The aim of this study was to determine the relationship between the weight status and the aerobic capacity of schoolers in Tijuana, Mexico. METHODS: This study’s samples were constituted by 275 children, 135 girls and 140 boys from 5th and 6th grade, between the ages of 10-12, currently enrolled in the morning and evening shifts. Weight, height, body-mass index and the maximum oxygen consumption (20 meter Shuttle Run Test) were evaluated. To identify relationship between the weight status with the aerobic capacity, the Pearson correlation coefficient was used. RESULTS: The overweight and obesity prevalence were 29% and 13% in boys and 33% and 12% in girls respectably. It was observed a moderate negative correlation but statistically significant between the weight status with the aerobic capacity (r= -0.437, p=0.001). CONCLUSION: In this population, the greater the weight was associated with low aerobic capacity. In conclusion, the aerobic capacity could be affected due to overweight, obesity, and a superior corporal weight than the recommended one for a certain height

Estimación de parámetros ambientales, fisiológicos y genéticos para el peso al destete y 18 meses y pruebas de progenie en un rebaño Cebú Brahman.

De los archivos de un rebaño de bovinos brahman, localizado en Valparaiso, Antioquia, se obtuvo información sobre 2482 pesos al destete y 406 a los 18 meses, de becerros nacidos de 698 vacas y 53 toros Brahman, reduciéndose los padres para pesos a los 18 meses. En el análisis de varianza se indujeron los efectos: sexo, año de nacimiento, época, edad de la madre al parto. La alta correlación genética entre el peso al destete y el peso a los 18 meses y el hecho de que el índice de herencia sea mayor para el pso al destete, permite concluír que la selección de toretes y novillas en este rebaño debe efectuarse a partir del destete (270 días) y de esta forma disminuír el intervalo generacional. Igualmente ayudará a disminuír la edad del primer parto, alargando la vida útil de las vacas, estas a su vez se pueden seleccionar en la población por el peso al destete de sus hijos dado el valor moderado para el coeficiente de repetición del peso al destete y el índice de herencia, junto con la correlación genética alta entre ambos peso