Reactive Oxygen Species (ROS) are known as important intracellular signaling molecules. These are also well known for their role in oxidative stress and cellular damage, leading to their involvement ...in several pathologies. Despite the widespread postulation of ROS mechanisms, little is actually known about the immediate response in living cells to the generation of these highly reactive compounds. The development of nanoplatforms incorporating photosensitizers would permit the generation of ROS at specific sub-cellular locations and determine the in situ cellular response. The work presented in this thesis describes the development of porphyrinic nanoplatforms for the controlled generation of ROS and investigates their impact on the surface marker expression of human Mesenchymal Stem Cells (hMSCs). Surface tailoring of polyacrylamide nanoparticles with alkyne and amine functionalities were exploited to achieve stable reactive chemical groups for further conjugation. Nanoplatforms surface was also modulated with trimethylammonium functionalities for the development of nanosystems for sub-cellular targeting and facilitated uptake. Physicochemical characterization of alkyne and alkyne/trimethylammonium functionalised constructs showed sizes in the range of 40 nm with a positive surface charge. Alkyne/trimethylammonium nanosystemswere found to be stable over long periods of time, whilst amino functionalized nanosystems were found to be prone to aggregation. Mechanisms of conjugation were exploited to create covalent linkage of porphyrinic photosensitizers to mono and dually functionalised constructs. Conjugation through "click chemistry" allowed stable coupling with alkyne and alkyne/trimethylammonium nanosystems. To overcome aggregation associated with amino functionalised nanoplatforms, porphyrin conjugated monomers were synthesised which resulted in stable polyacrylamide nanoparticles. The developed conjugated nanosystems showed final sizes in the range 40-100 nm, while conjugates with surface charges greater than + 20 mV have led to sizes higher than 100 nm. The effect of surface charge on cellular delivery was investigated and nanosystems with a surface charge in the range + 13 mV to + 18 mV proved optimal in terms of cell delivery and viability. It was found that highly charged nanosystems (above + 20 mV) remained attached to the cellular membrane and had a negative effect on cell viability. In addition, intracellular co-localisation studies showed preferential mitochondrial targeting of the delivered nanosystems. Production of ROS in nanoparticle treated hMSCs was achieved by exposure to light at wavelength of 575 nm. For porphyrin conjugated nanosystems a single light dosage resulted in a "blast zone" in the irradiated area where significant production of hydrogen peroxide was also observed. Titration of the amount of porphyrin conjugated at the surface of nanoparticles resulted in systems with different levels of ROS production. Control of ROS generation allowed development of a nanoplatform that was used to expose cells to repeated exposure of ROS over a time period of 100 minutes. The surface marker expression of hMSCs treated with porphyrin conjugated nanosystems was investigated. In the absence of light the surface marker expression of hMSCs was maintained, positive for CD29 and CD105 and negative for CD34 and CD45. Increased generation ROS in hMSCs did not produce alterations in the surface marker expression of cells, and over two generations of treated cells (light and nanoparticles) no changes were detected in surface marker expression. The developed nanoplatforms have the potential to be applied as a tool to investigate the cellular mechanisms and metabolism associated with different levels of oxidative stress. In addition, these nanosystems could also represent an innovative platform for theranostic applications (drug delivery/diagnostic).
Reactive Oxygen Species (ROS) are known as important intracellular signaling molecules. These are also well known for their role in oxidative stress and cellular damage, leading to their involvement ...in several pathologies. Despite the widespread postulation of ROS mechanisms, little is actually known about the immediate response in living cells to the generation of these highly reactive compounds. The development of nanoplatforms incorporating photosensitizers would permit the generation of ROS at specific sub-cellular locations and determine the in situ cellular response. The work presented in this thesis describes the development of porphyrinic nanoplatforms for the controlled generation of ROS and investigates their impact on the surface marker expression of human Mesenchymal Stem Cells (hMSCs). Surface tailoring of polyacrylamide nanoparticles with alkyne and amine functionalities were exploited to achieve stable reactive chemical groups for further conjugation. Nanoplatforms surface was also modulated with trimethylammonium functionalities for the development of nanosystems for sub-cellular targeting and facilitated uptake. Physicochemical characterization of alkyne and alkyne/trimethylammonium functionalised constructs showed sizes in the range of 40 nm with a positive surface charge. Alkyne/trimethylammonium nanosystemswere found to be stable over long periods of time, whilst amino functionalized nanosystems were found to be prone to aggregation. Mechanisms of conjugation were exploited to create covalent linkage of porphyrinic photosensitizers to mono and dually functionalised constructs. Conjugation through "click chemistry" allowed stable coupling with alkyne and alkyne/trimethylammonium nanosystems. To overcome aggregation associated with amino functionalised nanoplatforms, porphyrin conjugated monomers were synthesised which resulted in stable polyacrylamide nanoparticles. The developed conjugated nanosystems showed final sizes in the range 40-100 nm, while conjugates with surface charges greater than + 20 mV have led to sizes higher than 100 nm. The effect of surface charge on cellular delivery was investigated and nanosystems with a surface charge in the range + 13 mV to + 18 mV proved optimal in terms of cell delivery and viability. It was found that highly charged nanosystems (above + 20 mV) remained attached to the cellular membrane and had a negative effect on cell viability. In addition, intracellular co-localisation studies showed preferential mitochondrial targeting of the delivered nanosystems. Production of ROS in nanoparticle treated hMSCs was achieved by exposure to light at wavelength of 575 nm. For porphyrin conjugated nanosystems a single light dosage resulted in a "blast zone" in the irradiated area where significant production of hydrogen peroxide was also observed. Titration of the amount of porphyrin conjugated at the surface of nanoparticles resulted in systems with different levels of ROS production. Control of ROS generation allowed development of a nanoplatform that was used to expose cells to repeated exposure of ROS over a time period of 100 minutes. The surface marker expression of hMSCs treated with porphyrin conjugated nanosystems was investigated. In the absence of light the surface marker expression of hMSCs was maintained, positive for CD29 and CD105 and negative for CD34 and CD45. Increased generation ROS in hMSCs did not produce alterations in the surface marker expression of cells, and over two generations of treated cells (light and nanoparticles) no changes were detected in surface marker expression. The developed nanoplatforms have the potential to be applied as a tool to investigate the cellular mechanisms and metabolism associated with different levels of oxidative stress. In addition, these nanosystems could also represent an innovative platform for theranostic applications (drug delivery/diagnostic).
Objetivo: Asociar el síndrome de burnout (SB) y la satisfacción laboral (SL) en profesionales de la salud en un área de contingencia COVID-19 en el Instituto Nacional de Salud del Niño (INSN), 2022. ...Materiales y métodos: Estudio analítico transversal aplicado en 56 profesionales de la salud. Se usó el Maslach Burnout Inventory (MBI) y la Minnesota Satisfaction Questionnaire (MSQ) para la medición de las variables principales. Resultados: Se encontró un nivel bajo de SB en el 71,4 % y un nivel alto de SL en el 51,8 % de los en los profesionales. Los puntajes en los factores intrínsecos de la SL fueron de nivel medio en el 55,4 %. También se observó agotamiento emocional, despersonalización y un alto nivel de realización personal. Al parecer, el agotamiento emocional (rho = –0,30; p = 0,04) y la realización personal (rho = 0,50; p < 0,001) son predictores del SB. Conclusiones: En el área de contingencia COVID-19 no se evidenciaron altos niveles de burnout, lo que se refleja en un alto nivel de satisfacción en el personal de salud.
Objective: To associate burnout syndrome (BS) and work satisfaction (WS) in health professionals in a COVID-19 contingency area at the National Institute of Children's Health, 2022. Materials and methods: Cross-sectional analytical study applied in 56 health professionals. The Maslach Burnout Inventory (MBI) and the Minnesota Satisfaction Questionnaire (MSQ) were used to measure the main variables. Results: A low level of burnout (71.4%) and a high level of WS (51.8%) were found in professionals. The scores on the intrinsic factors of WS were of medium level in 55.4%. Also, there was emotional exhaustion, depersonalization and a high level of personal accomplishment. Emotional exhaustion (rho = –0.30; p = 0.04) and personal accomplishment (rho = 0.50; p < 0.001) appear to be predictors of BS. Conclusions: At COVID-19 contingency area, high levels of burnout were not evident, which is reflected in a high level of satisfaction among health personnel.
Objective. To relate functional performance and quality of family life in children and adolescents with cerebral palsy from the Instituto Nacional de Salud del Niño during 2021. Materials and ...methods. A retrospective analytical study that analyzed 80 children and adolescents between 2 and 18 years old with cerebral palsy, in a non-probabilistic way, who attended the Physical Medicine and Rehabilitation Service for outpatient consultation. The Pediatric Evaluation of Disability Inventory and the Beach Center Family Quality of Life Scale adapted to Latin America were applied. Results. There were 56% males and a median age of 7 (3-9). The most frequent diagnoses were spastic hemiparesis (32%) and spastic quadriparesis (31%). Slight correlations were observed between functional performance and satisfaction with support for people with disabilities (rho = 0.25; p = 0.026). At the same time, self-care (rho = 0.26; p = 0.022) and social performance (rho = 0.26; p = 0.021) were associated with satisfaction with support for people with disabilities. Conclusion. Functional performance was associated with quality of life domains such as satisfaction with health and safety and support for people with disabilities.
Objetivo. Asociar el desempeño funcional y la calidad de vida familiar de niños y adolescentes con parálisis cerebral del Instituto Nacional de Salud del Niño durante el año 2021. Materiales y métodos. Estudio analítico retrospectivo que analizó de forma no probabilística 80 niños y adolescentes entre 2 y 18 años con parálisis cerebral que acudieron por consulta externa al Servicio de Medicina Física y Rehabilitación. Se aplicaron el Pediatric Evaluation of Disability Inventory y la Escala de Calidad de Vida Familiar del Beach Center adaptado a Latinoamérica. Resultados. Hubo 56 % de varones y una mediana de la edad de 7 (3-9). Los diagnósticos más frecuentes fueron de hemiparesia espástica (32 %) y cuadriparesia espástica (31 %). Se observaron correlaciones leves entre el desempeño funcional y la satisfacción por el apoyo a las personas con discapacidad (rho = 0,25; p = 0,026). A la vez, el autocuidado (rho = 0,26; p = 0,022) y el funcionamiento social (rho = 0,26; p = 0,021) se asociaron con la satisfacción por el apoyo a las personas con discapacidad. Conclusión. El desempeño funcional se asoció con los dominios de la calidad de vida como satisfacción por la salud y seguridad y el apoyo a las personas con discapacidad.
The Andes is the most biodiverse region across the globe. In addition, some of the largest urban areas in South America are located within this region. Therefore, ecosystems and human population are ...affected by hydroclimate changes reported at global, regional and local scales. This paper summarizes progress of knowledge about long-term trends observed during the last two millennia over the entire Andes, with more detail for the period since the second half of the 20th century, and presents a synthesis of climate change projections by the end of the 21st century. In particular, this paper focuses on temperature, precipitation and surface runoff in the Andes. Changes in the Andean cryosphere are not included here since this particular topic is discussed in other paper in this Frontiers special issue, and elsewhere (e.g. IPCC,2019b). While previous works have reviewed the hydroclimate of South America and particular sectors (i.e., Amazon and La Plata basins, the Altiplano, Northern South America, etc.) this review includes for the first time the entire Andes region, considering all latitudinal ranges: tropical (North of 27°S), subtropical (27°S−37°S) and extratropical (South of 37°S). This paper provides a comprehensive view of past and recent changes, as well as available climate change projections, over the entire Andean range. From this review, the main knowledge gaps are highlighted and urgent research necessities in order to provide more mechanistic understanding of hydroclimate changes in the Andes and more confident projections of its possible changes in association with global climate change.
Quantitative descriptions of multi-cellular structures from optical microscopy imaging are prime to understand the variety of three-dimensional (3D) shapes in living organisms. Experimental models of ...vertebrates, invertebrates and plants, such as zebrafish, killifish, Drosophila or Marchantia, mainly comprise multilayer tissues, and even if microscopes can reach the needed depth, their geometry hinders the selection and subsequent analysis of the optical volumes of interest. Computational tools to "peel" tissues by removing specific layers and reducing 3D volume into planar images, can critically improve visualization and analysis.
We developed VolumePeeler, a versatile FIJI plugin for virtual 3D "peeling" of image stacks. The plugin implements spherical and spline surface projections. We applied VolumePeeler to perform peeling in 3D images of spherical embryos, as well as non-spherical tissue layers. The produced images improve the 3D volume visualization and enable analysis and quantification of geometrically challenging microscopy datasets.
ImageJ/FIJI software, source code, examples, and tutorials are openly available in https://cimt.uchile.cl/mcerda.
Copper bioavailability, specially to plants, is strongly dependent on its chemical form, as for most metals. Copper-contaminated soil can be treated in situ by the addition of minerals such as ...Na-bentonite, which mixed with surface soil, can transform this pollutant to non-bioavailable forms. In this work, shelter experiments were conducted to study the time evolution of Cu speciation, in pristine soil as well as in amended one. A selective sequential extraction method was employed to determine the metal speciation in the samples. The results show that the major metal fraction is the organic matter-bound one, whereas the exchangeable fraction is very low, even the first day after Cu addition. The time evolution shows a slow decrease of the organic-bound Cu and a corresponding increase of the most stable mineral fractions. With the addition of Na-bentonite to copper-contaminated soil, the most stable mineral fractions increase whereas the organic-bound one decreases, showing essentially similar time dependence of the several metal fractions. Sodium bentonite could be effectively used for remediation of soils polluted with Cu.
Mycobacterium abscessus is an opportunistic, extensively drug-resistant non-tuberculous mycobacterium. Few genomic studies consider its diversity in persistent infections. Our aim was to characterize ...microevolution/reinfection events in persistent infections. Fifty-three sequential isolates from 14 patients were sequenced to determine SNV-based distances, assign resistance mutations and characterize plasmids. Genomic analysis revealed 12 persistent cases (0-13 differential SNVs), one reinfection (15,956 SNVs) and one very complex case (23 sequential isolates over 192 months), in which a first period of persistence (58 months) involving the same genotype 1 was followed by identification of a genotype 2 (76 SNVs) in 6 additional alternating isolates; additionally, ten transient genotypes (88-243 SNVs) were found. A macrolide resistance mutation was identified from the second isolate. Despite high diversity, the genotypes shared a common phylogenetic ancestor and some coexisted in the same specimens. Genomic analysis is required to access the true intra-patient complexity behind persistent infections involving M. abscessus.
This study is a geochemical investigation of the Andean and Foreland basins of the Amazon River at high spatial and time resolution, carried out within the framework of the HYBAM research program ...(Hydro-geodynamics of the Amazon Basin). Monthly sampling was carried out at 27 gauging stations located in the upper tributaries of the Amazon Basin (from north to south: the Napo, Marañon, Ucayali, Madre de Dios-Beni and Mamore Rivers). The aim of this paper is to estimate the present-day chemical weathering rate (CWR), as well as the flux of CO₂ consumption from total and silicate weathering in the Andes and Foreland Amazon basins, and to discuss their distribution as a function of geomorphic and structural parameters. Based on the forward method, the Napo and other Ecuadorian basins present high silicate weathering rates in comparison with the other basins. We confirm that the Marañon and Ucayali Rivers control the Amazon hydrochemistry due to the presence of salt rocks and carbonates in these basins. The Madre de Dios, Beni and Mamore basins do not contribute much to the Amazon dissolved load. This north to south CWR gradient can be explained by the combination of decreasing weatherable lithology surface and decreasing runoff rates from the north to the south. The foreland part of the basins (or Mountain–Lowland transition) accounts for nearly the same proportion of the Amazon silicate chemical weathering and carbonate chemical weathering fluxes as the Andean part. This result demonstrates the importance of the sediment accumulation areas in the Amazon Basin weathering budget and can be explained by the occurrence of a higher temperature, the deposition of fresh sediments from Andean erosion and a higher sediment residence time than in the upper part of the basin. With a total CO₂ consumption rate of 744.10³moleskm⁻²year⁻¹ and a silicate CO₂ consumption rate of 300.10³moleskm⁻²year⁻¹, the Upper Amazon River (Andes+Foreland part) is the most intense part of the Amazon Basin in terms of atmospheric CO₂ consumption by weathering processes. It is an important CO₂ sink by weathering processes but accounts for only somewhat more than half of the CO₂ consumption by silicate weathering of the Amazon Basin. This result points out the importance of the Lowland part of the basin in the inorganic C silicate budget. The Upper Amazon accounts for 2–4% of the world's silicate CO₂ consumption, which is the same proportion as for the southern and southern-east Himalaya and Tibetan plateau.
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