25 research outputs found

    Chemical profiling of volatile components of the gametophyte and sporophyte stages of the hornwort leiosporoceros dussii (Leiosporocerotaceae) from Panama by HSSPME-GC-MS

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    We report for the first time the chemical profiling of volatile organic compounds (VOCs) of gametophyte and sporophyte life stages of Leiosporoceros dussii, from Panama by using headspace-solid phase microextraction-gas chromatography-mass spectrometry in order to assess distinguishing chemical markers between the male and female gametophytes, and sporophytes of this hornwort. A total of 27 VOCs were identified in L. dussii. Furthermore, the gametophyte and sporophyte showed clear differences in the type and amount of VOCs. The main constituents of L. dussii female thalli were menthacamphor (17.8%), hexanol (12.3%), and menthyl acetate (12.3%), while the major compounds of the male thalli were hexanol (25.3%), β-ionone (21.1%), benzeneacetaldehyde (17.6%), and β-cyclocitral (14.0%). The main VOCs of the sporophytes were hexanal (19.3%), β-cyclocitral (17.6%), 2-nonenal (15.8%), hexanol (12.5%), and β-ionone (10.2%). Unique compounds found in the female thalli were 3-pentanone, 3-octenol, nonanol, estragole, and menthyl acetate, and in the male thalli were methyl heptenone, nonanal, neoisomenthol, and bornyl acetate. Isomenthol, thymol, isomenthol acetate, and β-methylnaphthalene were only found in the sporophyte. The characteristic VOCs identified in L. dussii suggest a difference between the chemical constituents of L. dussii and other hornworts species. The presence of simple VOCs when compared with compounds previously characterized in another hornwort genera may support the distinct genetic nature of this species

    Reconstrucción cognitiva de los conceptos centrales de la función exponencial: un estudio de enfoque mixto

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    Este estudio presenta evidencias sobre la validación de un modelo cognitivo llamado descomposición genética para la reconstrucción del concepto función exponencial. Se encuesta a 22 estudiantes del profesorado de matemática y de maestría en didáctica de la matemática mediante la aplicación de un cuestionario desde un enfoque de metodología mixta. Se muestra evidencia de cómo los participantes del estudio utilizan de forma paralela el operador logaritmo y la función exponencial. Entre los resultados se destaca el rol que desempeña la gráfica, el uso de patrones y la potenciación para establecer las restricciones a la base de la relación exponencial. Sumado a lo anterior, se confirma el rol que desempeña la multiplicación recursiva de un número real positivo para poner de relieve la monotonía de la función exponencial. Se concluye que estos resultados permiten validar el modelo cognitivo propuesto de descomposición genética, vindicando los elementos teóricos que lo sustentan.This study presents evidence that validates a cognitive model called genetic decomposition for the reconstruction of the exponential function concept. Twenty-two students enrolled in a mathematics teaching degree and in a master's degree in didactics of mathematics are surveyed through the application of a questionnaire using a mixed methodology approach. The results show that the students surveyed use both the logarithm operator and the exponential function in parallel. The results underscore the roles played by graphs and the use of patterns and the power operation to establish restrictions at the base of the exponential relationship. In addition, the results confirm the role played by recursive multiplication of a positive real number to highlight the monotony of the exponential function. It is concluded that these results validate the proposed model of genetic decomposition, vindicating the theoretical elements that support it

    A modeling and machine learning approach to ECG feature engineering for the detection of ischemia using pseudo-ECG.

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    Early detection of coronary heart disease (CHD) has the potential to prevent the millions of deaths that this disease causes worldwide every year. However, there exist few automatic methods to detect CHD at an early stage. A challenge in the development of these methods is the absence of relevant datasets for their training and validation. Here, the ten Tusscher-Panfilov 2006 model and the O'Hara-Rudy model for human myocytes were used to create two populations of models that were in concordance with data obtained from healthy individuals (control populations) and included inter-subject variability. The effects of ischemia were subsequently included in the control populations to simulate the effects of mild and severe ischemic events on single cells, full ischemic cables of cells and cables of cells with various sizes of ischemic regions. Action potential and pseudo-ECG biomarkers were measured to assess how the evolution of ischemia could be quantified. Finally, two neural network classifiers were trained to identify the different degrees of ischemia using the pseudo-ECG biomarkers. The control populations showed action potential and pseudo-ECG biomarkers within the physiological ranges and the trends in the biomarkers commonly identified in ischemic patients were observed in the ischemic populations. On the one hand, inter-subject variability in the ischemic pseudo-ECGs precluded the detection and classification of early ischemic events using any single biomarker. On the other hand, the neural networks showed sensitivity and positive predictive value above 95%. Additionally, the neural networks revealed that the biomarkers that were relevant for the detection of ischemia were different from those relevant for its classification. This work showed that a computational approach could be used, when data is scarce, to validate proof-of-concept machine learning methods to detect ischemic events

    Antimicrobial Properties of Polyester/Copper Nanocomposites by Melt-Spinning and Melt-Blowing Techniques

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    In this study, textile fiber prototypes based on polyester and different Cu nanoparticles (CuNP) content were produced using melt-spinning to obtain bi-component multifilament fibers and melt-blowing to obtain non-woven fabrics. The prototypes were tested against pathogenic microorganisms such as S. aureus, E. coli, and C. albicans. It was shown that bi-component fibers offer excellent protection against pathogens, with up to 99% growth inhibition with 0.5% w/w for S. aureus and E. coli; meanwhile, non-woven fabric only shows activity against E. coli from 0.1% w/w of CuNP. Using different analytical techniques, it was possible to identify that the CuNP were confined exclusively in the outer cover of the bi-component fibers which may be associated with increased antimicrobial activity compared to the fibers in the non-woven fabric. The use of polymeric nanocomposites based on polyester/copper offers an alternative of great interest due to the versatility of the raw material and the high efficiency of copper nanoparticles as an antimicrobial additive

    Investigating the physiology of normothermic ex vivo heart perfusion in an isolated slaughterhouse porcine model used for device testing and training

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    BACKGROUND: The PhysioHeart™ is a mature acute platform, based isolated slaughterhouse hearts and able to validate cardiac devices and techniques in working mode. Despite perfusion, myocardial edema and time-dependent function degradation are reported. Therefore, monitoring several variables is necessary to identify which of these should be controlled to preserve the heart function. This study presents biochemical, electrophysiological and hemodynamic changes in the PhysioHeart™ to understand the pitfalls of ex vivo slaughterhouse heart hemoperfusion. METHODS: Seven porcine hearts were harvested, arrested and revived using the PhysioHeart™. Cardiac output, SaO2, glucose and pH were maintained at physiological levels. Blood analyses were performed hourly and unipolar epicardial electrograms (UEG), pressures and flows were recorded to assess the physiological performance. RESULTS: Normal cardiac performance was attained in terms of mean cardiac output (5.1 ± 1.7 l/min) and pressures but deteriorated over time. Across the experiments, homeostasis was maintained for 171.4 ± 54 min, osmolarity and blood electrolytes increased significantly between 10 and 80%, heart weight increased by 144 ± 41 g, free fatty acids (- 60%), glucose and lactate diminished, ammonia increased by 273 ± 76% and myocardial necrosis and UEG alterations appeared and aggravated. Progressively deteriorating electrophysiological and hemodynamic functions can be explained by reperfusion injury, waste product intoxication (i.e. hyperammonemia), lack of essential nutrients, ion imbalances and cardiac necrosis as a consequence of hepatological and nephrological plasma clearance absence. CONCLUSIONS: The PhysioHeart™ is an acute model, suitable for cardiac device and therapy assessment, which can precede conventional animal studies. However, observations indicate that ex vivo slaughterhouse hearts resemble cardiac physiology of deteriorating hearts in a multi-organ failure situation and signalize the need for plasma clearance during perfusion to attenuate time-dependent function degradation. The presented study therefore provides an in-dept understanding of the sources and reasons causing the cardiac function loss, as a first step for future effort to prolong cardiac perfusion in the PhysioHeart™. These findings could be also of potential interest for other cardiac platforms

    Optimization of human hepatocyte cultures for citotoxicity studies

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    Los cultivos de hepatocitos entregan un valioso acercamiento al estudio de las funciones metabólicas específicas del hígado, evaluación de citotoxicidad. No existen líneas humanas inmortales con función normal. La inmortalización de hepatocitos humanos con el método UCHT1(medio de cultivo condicionado por células tumorales de tiroides) permitirá prolongar la sobrevida y función de estos, siendo útil para evaluar funcionalidad y citotoxicidad. Objetivo: Optimizar el cultivo de hepatocitos humanos. Metodología: En cultivos primarios de hepatocitos humanos, se agregó medio UCHT1 cultivando en superficies de colágeno, polilisina, gelatina y matrigel. Como control positivo, se utilizó línea Gherschenson (GER) para evaluar curva de crecimiento y producción de Glucógeno (PAS). Se evaluó citotoxicidad (LIVE/DEAD) en hepatocitos GER expuestos a Metotrexato (10, 100 y 1000 mM) a 24, 48 y 72 hrs. Resultados: Se realizó 3 cultivos primarios. Fue efectiva la utilización de Polilisina y Colágeno. Duración 8 meses. No se ha realizado la curva de crecimiento, ni evaluación de funcionalidad en hepatocitos humanos. La línea GER tiene un crecimiento exponencial (tiempo duplicación: 36 hrs). Se observó producción de glucógeno en condiciones de diferenciación hasta 120 hrs. La citotoxicidad por Metotrexato tiene una curva dosis dependiente, significativa en todas las concentraciones (p<0,001) (CL50 a 1000 mM a 24 hrs). Conclusiones: Se logró establecer una línea primaria de hepatocitos humanos. La polilisina y el colágeno han optimizado el establecimiento de cultivos primarios. El método PAS permitió evaluar producción de glucógeno (diferenciación). Los valores de citotoxicidad demostraron un efecto dosis dependiente en las condiciones experimentales. Logrando estandarizar el método para evaluación futura de líneas celulares humanas

    El futuro incierto de las tierras y aguas protegidas

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    Las áreas protegidas están destinadas a salvaguardar la biodiversidad a perpetuidad, sin embargo, la evidencia sugiere que los cambios legales generalizados socavan la durabilidad y eficacia de las áreas protegidas. Documentamos estos cambios legales (eventos de degradación, reducción y eliminación de clasificación de áreas protegidas (PADDD)) en los Estados Unidos y los países amazónicos y compilamos los datos disponibles a nivel mundial. Los gobiernos de los Estados Unidos y los países amazónicos promulgaron 269 y 440 eventos PADDD, respectivamente. Entre 1892 y 2018, 73 países promulgaron 3749 eventos PADDD, eliminando 519,857 kilómetros cuadrados de las regulaciones de protección y templado en 1,659,972 kilómetros cuadrados adicionales; El 78% de los eventos se promulgaron desde 2000. La mayoría de los eventos PADDD (62%) están asociados con la extracción y el desarrollo de recursos a escala industrial, lo que sugiere que PADDD puede comprometer los objetivos de conservación de la biodiversidad. Se necesitan respuestas de políticas estratégicas para abordar la PADDD y mantener áreas protegidas efectivas.Protected areas are intended to safeguard biodiversity in perpetuity, yet evidence suggests that widespread legal changes undermine protected area durability and efficacy. We documented these legal changes-protected area downgrading, downsizing, and degazettement (PADDD) events-in the United States and Amazonian countries and compiled available data globally. Governments of the United States and Amazonian countries enacted 269 and 440 PADDD events, respectively. Between 1892 and 2018, 73 countries enacted 3749 PADDD events, removing 519,857 square kilometers from protection and tempering regulations in an additional 1,659,972 square kilometers; 78% of events were enacted since 2000. Most PADDD events (62%) are associated with industrial-scale resource extraction and development, suggesting that PADDD may compromise biodiversity conservation objectives. Strategic policy responses are needed to address PADDD and sustain effective protected areas.Q1Reflexión Económica, Administrativa y Contable (REAC
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