Búsqueda avanzada


Área de conocimiento




2721 resultados, página 1 de 10

Nanopartículas híbridas cargadas con un compuesto bioactivo y su efecto en biomarcadores neuroinflamatorios como potencial tratamiento de la enfermedad de Alzheimer

Hybrid nanoparticles loaded with a bioactive compound and their effect on neuroinflammatory biomarkers as a potential treatment for Alzheimer’s disease

Alondra Vargas Barona (2024, [Tesis de maestría])

La enfermedad de Alzheimer (EA) es una enfermedad neurodegenerativa progresiva caracterizada por el deterioro cognitivo asociado a la acumulación de la proteína beta amiloide (Aβ). La Aβ activa a las células gliales del cerebro, generando un aumento en la secreción de citocinas pro-inflamatorias que conducen a la neuroinflamación y muerte neuronal. Actualmente no existen tratamientos efectivos que curen o detengan su progresión, por ello, la EA se considera como una prioridad de salud mundial. Las principales limitaciones son la baja biodisponibilidad del fármaco y la impermeabilidad de la barrera hematoencefálica (BHE). Afortunadamente, la nanomedicina ha surgido como un campo prometedor para el desarrollo de nuevos sistemas para la entrega controlada y dirigida de fármacos hacia el cerebro. Por ello, en este trabajo se sintetizaron nanopartículas híbridas de polímeros y lípidos (NPsHPL) conjugadas con transferrina (Tf) para facilitar el cruce de la BHE, y cargadas con N-acetilcisteína (NAC) por su efecto anti-inflamatorio, y se llevó a cabo su caracterización fisicoquímica. Posteriormente se implementó un modelo in vitro con astrocitos humanos derivados de células pluripotentes inducidas (iPSC) provenientes de un paciente diagnosticado con la EA, las cuales se llevaron a un estado reactivo por la estimulación con lipopolisacárido (LPS). El cultivo de células fue tratado con las NPsHPL conjugadas con Tf y cargadas con NAC (NPsHPL-Tf-NAC) a 0.25 mg/mL y NAC libre a 5 mM. Los resultados mostraron que las NPsHPL-Tf-NAC modularon favorablemente la expresión de genes pro-inflamatorios, como la interleucina-1β (IL-1β), la proteína precursora de amiloide (APP) y la proteína ácida fibrilar glial (GFAP). Además, redujo la secreción de las citocinas pro-inflamatorias interleucina 6 (IL-6), IL-1β e interferóngamma (INF-γ), ambos casos respecto al grupo de células que no recibieron algún tratamiento. Por otra parte, la NAC libre sólo tuvo este efecto en la expresión de IL-1β y la secreción de las citocinas IL-6 e INF-γ. Estos resultados posicionan a las NPsHPL-Tf-NAC como un potencial tratamiento para la EA.

Alzheimer’s disease (AD) is a progressive neurodegenerative disease characterized by cognitive impairment associated with the accumulation of beta-amyloid protein (Aβ). Aβ activates glial cells in the brain, increasing the secretion of pro-inflammatory cytokines that lead to neuroinflammation and neuronal death. Currently, there are no effective treatments that cure or stop its progression, therefore AD is considered a global health priority. The main limitations are the low drug bioavailability and impermeability of the blood-brain barrier (BBB). Fortunately, nanomedicine has emerged as a promising field for the development of new nanosystems for the controlled and targeted delivery of drugs to the brain. Therefore, in this work, lipid–polymer hybrid nanoparticles (LPHNPs) conjugated with transferrin (Tf) to facilitate crossing the BBB, and loaded with N-acetylcysteine (NAC) for its anti-inflammatory effect were synthesized, and their physicochemical characterization was carried out. Subsequently, an in vitro model with human astrocytes derived from induced pluripotent stem cells (iPSC) from an AD diagnosed patient was implemented, which were brought to a reactive state by stimulation with lipopolysaccharide (LPS). The cell culture was treated with Tf-conjugated LPHNPs loaded with NAC (LPHNPs-Tf-NAC) at 0.25 mg/mL and free NAC at 5 mM. The results showed that LPHNPs-Tf-NAC favorably modulated the expression of pro-inflammatory genes, such as interleukin-1β (IL-1β), amyloid precursor protein (APP) and glial fibrillary acidic protein (GFAP). In addition, they reduced the secretion of the pro-inflammatory cytokines interleukin 6 (IL-6), IL-1β and interferon-gamma (INF-γ), both cases compared to the group of cells that did not receive any treatment. On the other hand, free NAC only had this effect on the expression of IL-1β and the secretion of the cytokines IL-6 and INF-γ. These results position LPHNPs-Tf-NAC as a potential treatment for AD.

nanopartículas híbridas; enfermedad de Alzheimer; neuroinflamación; astrocitos; iPSC; nanomedicina hybrid nanoparticles, Alzheimer’s disease, neuroinflammation; astrocytes; iPSC; nanomedicine BIOLOGÍA Y QUÍMICA CIENCIAS DE LA VIDA OTRAS ESPECIALIDADES DE LA BIOLOGÍA OTRAS OTRAS

Chronic toxicity of shrimp feed added with silver nanoparticles (Argovit-4®) in Litopenaeus vannamei and immune response to white spot syndrome virus infection

Carlos Rosendo Romo Quiñonez Píndaro Álvarez Ruiz CLAUDIO HUMBERTO MEJIA RUIZ NINA BOGDANCHIKOVA Alexey Pestryakov CARINA GAMEZ JIMENEZ WENCESLAO VALENZUELA QUIÑONEZ Magnolia Montoya Mejía EUSEBIO NAVA PEREZ (2022, [Artículo])

"In recent years, the application of silver nanoparticles (AgNPs) as antibacterial compounds has been widely used in human and veterinary medicine. In this work, we investigated the effects of AgNPs (Argovit-4 R ) as feed additives (feed-AgNPs) on shrimp (Litopenaeus vannamei) using three different methods: 1) chronic toxicity after 28 days of feeding, 2) Effects against white spot syndrome virus (WSSV) challenged by oral route, and 3) transcriptional responses of immune-related genes (PAP, ProPO, CTL-3, Crustin, PEN3, and PEN4) following WSSV infection. The results showed that the feed-AgNPs did not interfere with the growth and survival of shrimp. Also, mild lesions in the hepatopancreas were recorded, proportional to the frequency of the feed-AgNP supply. Challenge test versus WSSV showed that feeding every 7 days with feed-AgNPs reduced mortality, reaching a survival rate of 53%, compared to the survival rates observed in groups fed every 4 days, daily and control groups of feed-AgNPs for the 30%, 10%, and 7% groups, respectively. Feed-AgNPs negatively regulated the expression of PAP, ProPO, and Crustin genes after 28 days of treatment and altered the transcriptional responses of PAP, ProPO, CTL-3, and Crustin after WSSV exposure. The results showed that weekly feeding-AgNPs could partially prevent WSSV infection in shrimp culture. However, whether or not transcriptional responses against pathogens are advantageous remains to be elucidated."

Silver nanoparticles, Shrimp, Aquaculture, Chronic toxicity, WSSV, AgNP, Argovit, Litopenaeus vannamei , Silver fed, White spot syndrome virus BIOLOGÍA Y QUÍMICA CIENCIAS DE LA VIDA INMUNOLOGÍA INMUNIZACIÓN INMUNIZACIÓN

Análisis numérico del clima interior en un invernadero de tres naves con ventilación mecánica

JORGE FLORES VELAZQUEZ ENRIQUE MEJIA SAENZ ABRAHAM ROJANO AGUILAR (2011, [Artículo])

Uno de los principales problemas que enfrenta la agricultura en invernaderos, sobre todo en regiones de clima cálido, es moderar y controlar los problemas derivados del incremento de temperatura que ocurre en marcados periodos del año, ya que reducen la calidad y cantidad de la cosecha. Un método efectivo para el control del clima es la ventilación (natural o forzada) y aunque la ventilación forzada sea más predecible que la natural, su descripción es compleja y una simplificación obliga un mayor conocimiento del proceso. El objetivo de este trabajo fue validar y aplicar un modelo numérico basado en la dinámica de fluidos computacional (CFD) para el análisis climático de un invernadero cenital de tres naves sin cultivo y con ventilación forzada.

Invernaderos Análisis numérico Clima INGENIERÍA Y TECNOLOGÍA

Control óptimo de un sistema de presas: un enfoque de perturbaciones pequeñas a la solución de programación dinámica estocástica

JAIME COLLADO MOCTEZUMA (1993, [Artículo])

Un número importante de problemas hidrológicos prácticos, entre ellos la optimización de la operación de un sistema de presas, puede formularse mediante programación dinámica estocástica. Sin embargo, un método de solución factible no existe, excepto para problemas con estructura lineal-cuadrática o para sistemas con pocas variables de estado. Este artículo propone un método analítico-numérico a la solución del control óptimo estocástico de malla cerrada. La solución óptima está dada por el control determinístico más un término de corrección que toma en cuenta los efectos de la estocasticidad en una caracterización de segundos momentos. Se supone que dicho término es pequeño en comparación con el control determinístico y se obtiene una solución de perturbaciones pequeñas. Este método puede ser usado como una solución subóptima para problemas donde no es factible usar programación estocástica clásica. Comparaciones con métodos convencionales muestran que el método ofrece resultados muy cercanos al óptimo, incluso cuando la hipótesis de perturbaciones pequeñas es sólo aproximadamente satisfecha. Una ventaja atractiva del método propuesto es que no requiere discretización de las variables de estado ni de las de control, eludiendo el así llamado maleficio de la dimensionalidad.

Presas Modelos estocásticos Análisis numérico INGENIERÍA Y TECNOLOGÍA

Variability of Microcirculation Detected by Blood Pulsation Imaging

Alexei Kamshilin (2013, [Artículo])

The non-invasive assessment of blood flow is invaluable for the diagnostic and monitoring treatment of numerous vascular and neurological diseases. We developed a non-invasive and non-contact method of blood pulsation imaging capable of visualizing and monitoring of the two-dimensional distribution of two key parameters of peripheral blood flow: the blood pulsation amplitude and blood pulsation phase. The method is based on the photoplethysmographic imaging in the reflection mode. In contrast with previous imaging systems we use new algorithm for data processing which allows two dimensional mapping of blood pulsations in large object's areas after every cardiac cycle. In our study we carried out the occlusion test of the arm and found (i) the extensive variability of 2D-distribution of blood pulsation amplitude from one cardiac cycle to another, and (ii) existence of the adjacent spots to which the blood is asynchronously supplied. These observations show that the method can be used for studying of the multicomponent regulation of peripheral blood circulation. The proposed technique is technologically simple and cost-effective, which makes it applicable for monitoring the peripheral microcirculation in clinical settings for example, in diagnostics or testing the efficiency of new medicines. © 2013 Kamshilin et al.

algorithm, article, blood analysis, heart cycle, human, human experiment, image analysis, imaging system, male, microcirculation, peripheral circulation, photoelectric plethysmography, process development, Algorithms, Diagnostic Imaging, Diagnostic T CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA MATEMÁTICAS ANÁLISIS NUMÉRICO ANÁLISIS NUMÉRICO

Procesos oceanográficos asociados al desarrollo y dispersión de florecimientos de Gymnodinium catenatum en el norte del Golfo de California

Oceanographic processes associated with harmful algal blooms of Gymnodinium catenatum development and dispersal in the northern Gulf of California

GABRIELA RESENDIZ COLORADO (2023, [Tesis de doctorado])

Durante los últimos años, durante la temporada de invierno y primavera, se ha detectado la presencia de florecimientos algales nocivos (FAN) causados por el dinoflagelado Gymnodinium catenatum en el norte del golfo de California (NGC). Estos eventos tienen impactos ecológicos, económicos y sociales negativos porque G. catenatum es una especie productora de saxitoxina, la cual, está asociada al envenenamiento paralítico por consumo de mariscos, lo que origina que la autoridad sanitaria se vea en la necesidad de implementar vedas en áreas de extracción de almeja generosa en el NGC al detectar producto contaminado. Por lo tanto, es necesario conocer los procesos físicos que provocan la ocurrencia y recurrencia de estos eventos, así como contar con un sistema de monitoreo y alerta temprana que permita tomar decisiones y acciones oportunas de mitigación contra los efectos perjudiciales de estos fenómenos. En este trabajo se abordaron estas necesidades de investigación por medio de la implementación de un método de detección remota de estos FAN, utilizando la clasificación de máxima verosimilitud basada en los datos de dos eventos sucedidos en 2015 y 2017. Los resultados de este enfoque fueron satisfactorios al reproducir la temporalidad de la presencia de la especie documentada por medio de muestreos semanales en la bahía de San Felipe, así como de la detección geográfica en las áreas que se conocen que son afectadas recurrentemente. Para estudiar los procesos físicos asociados a estos FAN, se implementó un modelo hidrodinámico usando el Sistema de Modelación Oceánica Regional (ROMS) para el norte del golfo de California. A partir de este modelo se obtuvieron datos de variables como energía cinética turbulenta, temperatura, corrientes y se complementaron con datos de esfuerzo de fondo producido por oleaje estimados a partir de datos de la quinta generación del reanálisis atmosférico del clima global del ECMWF (ERA-5), los análisis de estas variables y la abundancia semanal de G. catenatum permitieron identificar que los principales procesos asociados a la formación de estos florecimientos es el incremento del esfuerzo de fondo asociado al oleaje y la turbulencia. Estos, a su vez, tienen una relación con el cambio en el patrón del viento que se caracteriza por ser del noroeste durante las temporadas de invierno y primavera. Respecto a la dispersión de los florecimientos algales, con base en los datos obtenidos del modelo hidrodinámico, se realizaron experimentos

During the recent winter and spring seasons, harmful algal blooms (HABs) caused by the dinoflagellate Gymnodinium catenatum have been detected in the northern Gulf of California (NGC). These events have negative ecological, economic, and social impacts because G. catenatum is a species producer of saxitoxin, which is associated with paralytic shellfish poisoning, which causes the need to implement bans by the health authority in extraction areas of generous clam in the NGC when detecting contaminated products. Therefore, it is necessary to identify the physical processes that cause the occurrence and recurrence of these events and have a monitoring and early warning system that allows timely decisions and mitigation actions to be taken against the harmful effects of these henomena. In this work, these research gaps are approached by implementing a remote detection method for these HABs, using maximum likelihood classification based on data from two events in 2015 and 2017. The results of this approach were satisfactory by reproducing the temporality presence of Gymnodinium catenatum documented through weekly sampling in San Felipe Bay, as well as geographic detection in areas known to be recurrently affected. To study the physical processes associated with these HABs, a hydrodynamic model was implemented using the Regional Ocean Modeling System (ROMS) for the northern Gulf of California. From this model, variables such as turbulent kinetic energy, temperature, and currents were obtained and were complemented with data on bottom stress produced by waves estimated from the fifth generation ECMWF atmospheric reanalysis of the global climate (ERA-5) data. Analyzing these variables and the weekly abundance of G. catenatum, it was possible that the processes associated with forming these blooms are the increase in bottom stress related to waves and turbulence. These processes are related to the change in the wind pattern characterized by northwest winds during the winter and spring seasons. Regarding the dispersion of algal blooms, based on the data obtained from the hydrodynamic model, lagrangian experiments were carried out to estimate the transport of the HAB. The results showed that the modeled dispersion corresponds with the detection carried out with the remote sensing method mplemented in this work for the 2017 event. The results obtained from this work are essential knowledge for the operational implementation of monitoring and early warning systems ..

Gymnodinium catenatum, florecimientos algales nocivos, percepción remota, modelación hidrodinámica, norte del golfo de California : Gymnodinium catenatum, harmful algal bloom, remote sensing, hydrodynamic modeling, northern Gulf of California BIOLOGÍA Y QUÍMICA CIENCIAS DE LA VIDA OTRAS ESPECIALIDADES DE LA BIOLOGÍA OTRAS OTRAS

Hyperiid amphipods from the Gulf of Ulloa and offshore region, Baja California: The possible role of the gelatinous zooplankton as a transport vector into the coastal shelf waters

Bertha Lavaniegos (2020, [Artículo])

Hyperiid amphipod species from the Gulf of Ulloa, Baja California, and the adjacent region (from the shelf break to 200 km offshore) were analyzed to evaluate diversity and abundances. This productive area supports small-scale commercial fisheries, including sand bass (Paralabrax nebulifer), California spiny lobster (Panulirus interruptus), abalones, clams, and others. Strong coastal upwelling events were observed during summer seasons of the period 2002-2008 between Punta Eugenia and Punta Abreojos. The upwelling plumes at Punta Abreojos are transported southward in slope waters bordering the coastal shelf of the Gulf of Ulloa, contributing to the separation of coastal and oceanic regions, and explain differences in amphipod diversity and abundances between both regions. In the offshore region, the most abundant species were Vibilia armata, Lestrigonus schizogeneios, Primno brevidens, and Eupronoe minuta, similar to previous findings in northern regions of Baja California and southern California. However, abundances of these species were lower (10-30 individuals/1000 m3), only reaching 20-50% of abundance levels reported off northern Baja California. In the coastal shelf of the Gulf of Ulloa, amphipods were virtually absent during 2002, 2003 and 2006. However, during 2004 and 2005, abundances of P. brevidens increased (54 and 20 ind/1000 m3, respectively). Moreover, during the late summer of 2007, abundances of L. schizogeneios, P. brevidens, Lycaea nasuta, Lycaea pulex, and Simorhynchotus antennarius increased considerably (261, 39, 31, 68, 416 ind/1000 m3, respectively), indicating occasional utilization of the coastal shelf by pelagic amphipods. Changes in gelatinous populations (medusae, siphonophores, ctenophores, doliolids, and salps) paralleled changes in hyperiid populations, with highest abundances in 2005-2008 in the coastal shelf. Significant correlations of 17 amphipod species with gelatinous taxa, which are often used as host organisms by hyperiid amphipods, suggest that gelatinous presence enhanced hyperiid abundance and promoted the progression of hyperiid amphipods onto the coastal shelf during parts of the 2002-2008 period. © 2020 Bertha E. Lavaniegos. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

abalone, Amphipoda, article, Baja California, clam, clinical article, Ctenophora, Eugenia, female, fishery, human, human experiment, male, medusa, nonhuman, Panulirus interruptus, plume, summer, zooplankton, Amphipoda, animal, California, ecosystem, CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA CIENCIAS DE LA TIERRA Y DEL ESPACIO OCEANOGRAFÍA OCEANOGRAFÍA

A simple extension to the CMASA method for the prediction of catalytic residues in the presence of single point mutations

David Israel Flores Granados (2014, [Artículo])

The automatic identification of catalytic residues still remains an important challenge in structural bioinformatics. Sequence-based methods are good alternatives when the query shares a high percentage of identity with a well-annotated enzyme. However, when the homology is not apparent, which occurs with many structures from the structural genome initiative, structural information should be exploited. A local structural comparison is preferred to a global structural comparison when predicting functional residues. CMASA is a recently proposed method for predicting catalytic residues based on a local structure comparison. The method achieves high accuracy and a high value for the Matthews correlation coefficient. However, point substitutions or a lack of relevant data strongly affect the performance of the method. In the present study, we propose a simple extension to the CMASA method to overcome this difficulty. Extensive computational experiments are shown as proof of concept instances, as well as for a few real cases. The results show that the extension performs well when the catalytic site contains mutated residues or when some residues are missing. The proposed modification could correctly predict the catalytic residues of a mutant thymidylate synthase, 1EVF. It also successfully predicted the catalytic residues for 3HRC despite the lack of information for a relevant side chain atom in the PDB file. © 2014 Flores et al.

1UU9 protein, 3HRC protein, protein, thymidylate synthase, unclassified drug, protein kinase, thymidylate synthase, accuracy, algorithm, Article, CMASA, CMASA Substitution Matrix, Contact Matrix Average Deviation, controlled study, correlation coeffi CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA MATEMÁTICAS ANÁLISIS NUMÉRICO ANÁLISIS NUMÉRICO

Métodos para calcular capacidades de embalse

LESLIE SKERTCHLY MOLINA (1989, [Artículo])

En México, el cálculo de la capacidad de embalse es un problema al que no se ha dado la debida importancia. Tradicionalmente, se han empleado dos métodos: el de la curva masa y el de modelos de simulación; usando, en ambos casos, los registros de escurrimientos disponibles. En este artículo se describen, comentan y ejemplifican algunos otros métodos de aplicación sencilla y efectiva, que permiten el empleo tanto de los registros históricos de escurrimientos como los generados en forma sintética, ampliando la longitud de los originales. Se presenta una evaluación de los métodos descritos y se hacen comparaciones entre ellos, relativas a su eficiencia y a la información que producen. Por último, se desarrollan otras técnicas basadas en las descritas, que permiten no sólo calcular la capacidad de embalse, sino que proveen más información útil para el diseño de sistemas

de aprovechamientos hidráulicos.

Capacidad de embalse Aprovechamiento hidráulico Modelos estocásticos INGENIERÍA Y TECNOLOGÍA

Movements of scalloped hammerhead sharks (Sphyrna lewini) at Cocos Island, Costa Rica and between oceanic islands in the Eastern Tropical Pacific

Elena Nalesso (2019, [Artículo])

Many species of sharks form aggregations around oceanic islands, yet their levels of residency and their site specificity around these islands may vary. In some cases, the waters around oceanic islands have been designated as marine protected areas, yet the conservation value for threatened shark species will depend greatly on how much time they spend within these protected waters. Eighty-four scalloped hammerhead sharks (Sphyrna lewini Griffith & Smith), were tagged with acoustic transmitters at Cocos Island between 2005–2013. The average residence index, expressed as a proportion of days present in our receiver array at the island over the entire monitoring period, was 0.52±0.31, implying that overall the sharks are strongly associated with the island. Residency was significantly greater at Alcyone, a shallow seamount located 3.6 km offshore from the main island, than at the other sites. Timing of presence at the receiver locations was mostly during daytime hours. Although only a single individual from Cocos was detected on a region-wide array, nine hammerheads tagged at Galapagos and Malpelo travelled to Cocos. The hammerheads tagged at Cocos were more resident than those visiting from elsewhere, suggesting that the Galapagos and Malpelo populations may use Cocos as a navigational waypoint or stopover during seasonal migrations to the coastal Central and South America. Our study demonstrates the importance of oceanic islands for this species, and shows that they may form a network of hotspots in the Eastern Tropical Pacific. © 2019 Nalesso et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

article, Cocos Island, human, monitoring, nonhuman, resident, shark, South America, animal, Costa Rica, environmental protection, island (geological), movement (physiology), physiology, season, shark, Animals, Conservation of Natural Resources, Costa CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA CIENCIAS DE LA TIERRA Y DEL ESPACIO OCEANOGRAFÍA OCEANOGRAFÍA