Identificación de nuevos sistemas de transporte de nitrato-nitrito en la levadura Hansenula polymorpha. Caracterización de NAR1 y CHL1

Esta tesis doctoral está dedicada fundamentalmente a la identificación y caracterización de transportadores de nitrato/nitrito de la levadura H. polymorpha. El uso de las herramientas bioinformáticas nos ha permitido identificar dos proteínas denominadas Nar1 y Chl1 que comparten similitud de secuencia con los respectivos transportadores de nitrito y nitrato descritos en otros organismos. Los resultados del presente trabajo indican que Nar1 es una proteína ubicada en la membrana plasmática que regula la concentración intracelular de nitrito mediante su excreción. De esta forma, las células toman el nitrato del medio principalmente a través del transportador de nitrato y nitrito de alta afinidad, Ynt1. Una vez en el citoplasma, el nitrato se reduce a nitrito, cuyo excedente es devuelto al medio extracelular a través de Nar1, y de otro(s) sistema(s). Pensamos que esto mantiene el nitrito intracelular por debajo de los niveles tóxicos. A su vez, demostramos que los niveles de Ynt1 están regulados por el nitrito presente en el medio de cultivo. Por otra parte, los resultados obtenidos indican que la proteína Chl1 participa en la excreción de aminoácidos, cuando la concentración intracelular del amonio alcanza cotas tóxicas. La acumulación de fuentes reducidas en el interior de las células afectadas en Chl1 disminuyen el grado de activación de la vía calcineurina disminuyendo a su vez los niveles de expresión de los genes de la vía de asimilación de nitrato. En conjunto, estos resultados nos han permitido conocer nuevos elementos que participan en la asimilación de nitrato, si bien ninguno de ellos parece mediar directamente el transporte de nitrato o nitrito al interior de la célul

Estudio de microestructuras dendríticas mediante análisis fractal

Tesis (Maestría en Ciencias de la Ingeniería Mecánica con Especialidad en Materiales) UANLUANLhttp://www.uanl.mx

Modelos de aprendizaje automático para el apoyo en la clasificación de tipos de cáncer a partir de datos estructurados y no estructurados de expedientes clínicos

103 páginas. Maestría en Ciencias de la Computación.La existencia de grandes volúmenes de datos generados por el área de la salud presenta una oportunidad importante para su análisis. Este puede obtener información que ayude a los médicos en el proceso de toma de decisiones para el diagnóstico o tratamiento de enfermedades, tales como el cáncer. El presente trabajo presenta una metodología para la clasificación de pacientes con cáncer de hígado, pulmón y pecho, a través de modelos de aprendizaje automático, para obtener el modelo que mejor se desempeña en la clasificación. La metodología considera tres modelos de la clasificación: Máquinas de Soporte Vectorial (SVM), Perceptrón Multi-Capa (MLP) y Ada- Boost utilizando tanto la información estructurada como no estructurada de los expedientes clínicos de los pacientes. Los resultados obtenidos muestran que el mejor modelo de clasificación fue el MLP utilizando solamente datos no estructurados, obteniendo un 89% de precisión, mostrando la utilidad de este tipo de datos en la clasificación de pacientes con cáncer.The existence of large volumes of data generated by the health area presents an important opportunity for analysis. This can obtain information to support physicians in the decisionmaking process for the diagnosis or treatment of diseases, such as cancer. The present work shows a methodology for the classification of patients with liver, lung and breast cancer, through machine learning models, to obtain the model that performs best in the classification. The methodology considers three classification models: Support Vector Machines (SVM), Multi-Layer Perceptron (MLP) and AdaBoost using both structured and unstructured information from the patient's clinical records. Results show that the best classification model is MLP using only unstructured data, obtaining 89% of precision, showing the usefulness of this type of data in the classification of cancer patients.Investigación realizada con el apoyo del Consejo Mexiquense de Ciencia y Tecnología (COMECYT)

Low pO2 selectively inhibits K channel activity in chemoreceptor cells of the mammalian carotid body

The hypothesis that changes in environmental O2 tension (pO2) could affect the ionic conductances of dissociated type I cells of the carotid body was tested. Cells were subjected to whole-cell patch clamp and ionic currents were recorded in a control solution with normal pO2 (pO2 = 150 mmHg) and 3-5 min after exposure to the same solution with a lower pO2. Na and Ca currents were unaffected by lowering pO2 to 10 mmHg, however, in all cells studied (n = 42) exposure to hypoxia produced a reversible reduction of the K current. In 14 cells exposed to a pO2 of 10 mmHg peak K current amplitude decreased to 35 +/- 8% of the control value. The effect of low pO2 was independent of the internal Ca2+ concentration and was observed in the absence of internal exogenous nucleotides. Inhibition of K channel activity by hypoxia is a graded phenomenon and in the range between 70 and 120 mmHg, which includes normal pO2 values in arterial blood, it is directly correlated with pO2 levels. Low pO2 appeared to slow down the activation time course of the K current but deactivation kinetics seemed to be unaltered. Type I cells subjected to current clamp generate large Na- and Ca-dependent action potentials repetitively. Exposure to low pO2 produces a 4-10 mV increase in the action potential amplitude and a faster depolarization rate of pacemaker potentials, which leads to an increase in the firing frequency. Repolarization rate of individual action potentials is, however, unaffected, or slightly increased. The selective inhibition of K channel activity by low pO2 is a phenomenon without precedents in the literature that explains the chemoreceptive properties of type I cells. The nature of the interaction of molecular O2 with the K channel protein is unknown, however, it is argued that a hemoglobin-like O2 sensor, perhaps coupled to a G protein, could be involved

Ionic currents in dispersed chemoreceptor cells of the mammalian carotid body

Ionic currents of enzymatically dispersed type I and type II cells of the carotid body have been studied using the whole cell variant of the patch-clamp technique. Type II cells only have a tiny, slowly activating outward potassium current. By contrast, in every type I chemoreceptor cell studied we found (a) sodium, (b) calcium, and (c) potassium currents. (a) The sodium current has a fast activation time course and an activation threshold at approximately -40 mV. At all voltages inactivation follows a single exponential time course. The time constant of inactivation is 0.67 ms at 0 mV. Half steady state inactivation occurs at a membrane potential of approximately -50 mV. (b) The calcium current is almost totally abolished when most of the external calcium is replaced by magnesium. The activation threshold of this current is at approximately -40 mV and at 0 mV it reaches a peak amplitude in 6-8 ms. The calcium current inactivates very slowly and only decreases to 27% of the maximal value at the end of 300-ms pulses to 40 mV. The calcium current was about two times larger when barium ions were used as charge carriers instead of calcium ions. Barium ions also shifted 15-20 mV toward negative voltages the conductance vs. voltage curve. Deactivation kinetics of the calcium current follows a biphasic time course well fitted by the sum of two exponentials. At -80 mV the slow component has a time constant of 1.3 +/- 0.4 ms whereas the fast component, with an amplitude about 20 times larger than the slow component, has a time constant of 0.16 +/- 0.03 ms. These results suggest that type I cells have predominantly fast deactivating calcium channels. The slow component of the tails may represent the activity of a small population of slowly deactivating calcium channels, although other possibilities are considered. (c) Potassium current seems to be mainly due to the activity of voltage-dependent potassium channels, but a small percentage of calcium-activated channels may also exist. This current activates slowly, reaches a peak amplitude in 5-10 ms, and thereafter slowly inactivates. Inactivation is almost complete in 250-300 ms. The potassium current is reversibly blocked by tetraethylammonium. Under current-clamp conditions type I cells can spontaneously fire large action potentials. These results indicate that type I cells are excitable and have a variety of ionic conductances. We suggest a possible participation of these conductances in chemoreception

Characterization of the chemical composition of banana peels from southern Brazil across the seasons using nuclear magnetic resonance and chemometrics

Banana peels are a source of important bioactive compounds, such as phenolics, carotenoids, biogenic amines, among others. For industrial usage of that by-product, a certain homogeneity of its chemical composition is claimed, a trait affected by the effect of (a)bioatic ecological factors. In this sense, this study aimed to investigate the banana peels chemical composition, to get insights on eventual metabolic changes caused by the seasons, in southern Brazil. For this purpose, a Nuclear Magnetic Resonance (NMR)-based metabolic profiling strategy was adopted, followed by chemometrics analysis, using the specmine package for the R environment. The obtained results show that the different seasons can, in fact, influence the metabolic composition, namely the levels of metabolites extracted from the bananas peels. The analytical approach herein adopted, i.e., NMR-based metabolomics coupled to chemometrics analysis, seems to enable identifying the chemical heterogeneity of banana peels over the harvest seasons, allowing obtaining standardized extracts for further technological purposes of usage.CAPES -Coordenação de Aperfeiçoamento de Pessoal de Nível Superior(407323/2013-9)info:eu-repo/semantics/publishedVersio

Influencia de los medios de comunicación en la desición de acudir a la consulta odontológica.

En la actualidad los medios de comunicación masivos tienen un gran impacto en la vida cotidiana de las personas, influyendo en sus actos y decisiones cotidianas. El objetivo de esta investigación es determinar cómo influyen los medios de comunicación en la decisión de acudir a la consulta odontológica. El diseño del proyecto fue descriptivo, abierto, observacional, retrospectivo y transversal. Se realizó un sondeo aleatorio por medio de una encuesta a 288 personas incluyendo a hombres y mujeres entre 18 y 40 años con independencia económica, nivel socioeconómico de medio a alto y sin problemas dentales severos. El análisis de los datos fue por estadística descriptiva y por medio de la Chi cuadrada para ver la asociación entre variables nominales. Los resultados encontrados demostraron que el 58% de los encuestados admitió el deseo de acudir al odontólogo después de ver publicidad odontológica revelando tener asociación estadística (p=0.0299). Así mismo los encuestados frecuentaron mayormente el uso del internet siendo utilizado en el 73% de los casos. Con esta investigación se encontró que la población es influenciada para acudir a la consulta dental al ser expuestos a la publicidad acerca de la odontología en los medios de comunicación masiva

Control of the whitefly Bemisia tabaci (Genn.) in greenhouses

A formulation based on neem oil (Azadirachta indica), chamomile (Matricaria chamomilla), lechuguilla (Agave lechuguilla torrey) and cactus pectin extracts at different concentrations was used in greenhouses to control the whitefly Bemisia tabaci (Genn.).  For moth monitoring, ecological water traps were used to which Noctovi® dipteran pheromones and a food component based on 50% sugar and 20% powdered yeast were added. The work was carried out in six tomato and strawberry production greenhouses located in the city of Durango, in northern Mexico, from August to November 2014. Plant extracts formulated with lechugilla surfactant based on chicalote (Argemone mexicana L.), skunk epazote (Chenopodium glaucum) and higuerilla (Ricinus communis) were used as controls and sprayed at intervals of 15 days each. Field results indicate that the formulation based on neem oil, nopal pectin, chamomile and lechuguilla extracts presented a moth mortality rate of 60% in tomato crops and 62% in strawberry crops

A New Perspective on Huntington's Disease: How a Neurological Disorder Influences the Peripheral Tissues

Huntington’s disease (HD) is a neurodegenerative disorder caused by a toxic, aggregationprone expansion of CAG repeats in the HTT gene with an age-dependent progression that leads to behavioral, cognitive and motor symptoms. Principally affecting the frontal cortex and the striatum, mHTT disrupts many cellular functions. In fact, increasing evidence shows that peripheral tissues are affected by neurodegenerative diseases. It establishes an active crosstalk between peripheral tissues and the brain in different neurodegenerative diseases. This review focuses on the current knowledge of peripheral tissue effects in HD animal and cell experimental models and identifies biomarkers and mechanisms involved or affected in the progression of the disease as new therapeutic or early diagnostic options. The particular changes in serum/plasma, blood cells such as lymphocytes, immune blood cells, the pancreas, the heart, the retina, the liver, the kidney and pericytes as a part of the blood–brain barrier are described. It is important to note that several changes in different mouse models of HD present differences between them and between the different ages analyzed. The understanding of the impact of peripheral organ inflammation in HD may open new avenues for the development of novel therapeutic targets

Diterpenoids from the Brown Alga Rugulopteryx okamurae and Their Anti-Inflammatory Activity

Brown algae of the Family Dictyotaceae produce an array of structurally diverse terpenoids, whose biomedical potential in the anti-inflammatory area has been scarcely explored. Herein, the chemical study of the alga Rugulopteryx okamurae has led to the isolation of ten new diterpenoids: rugukadiol A (1), rugukamurals A–C (2–4), and ruguloptones A–F (6–10). The structures of the new compounds were established by spectroscopic means. Compound 1 exhibits an unprecedented diterpenoid skeleton featuring a bridged tricyclic undecane system. Compounds 2–10 belong to the secospatane class of diterpenoids and differ by the oxygenated functions that they contain. In antiinflammatory assays, the new diterpenoid 1 and the secospatanes 5 and 10 significantly inhibited the production of the inflammatory mediator NO in LPS-stimulated microglial cells Bv.2 and macrophage cells RAW264.7. Moreover, compounds 1 and 5 were found to strongly inhibit the expression of Nos2 and the pro-inflammatory cytokine Il1b in both immune cell lines