Browsing by Author "Rojas, Pablo"

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    Análisis de los fenotipos y genotipos de resistencia a eritromicina y clindamicina en cepas de Streptococcus pyogenes aisladas en Chile en un período de 10 años
    (2011) Rodríguez, Carlos; Rojas, Pablo; Wozniak, Aniela; Kalergis, Alexis M.; Cerón, Inés; Riedel, Ingrid; Román, Juan C.; Villarroel, Luis A.; Berríos, Ximena; Bavestrello, Luis; García, Patricia
    Background: Macrolide and lincosamide resistance in Streptococcus pyogenes is due to the acquisition of mef, ermB and ermA genes, which confer different resistance phenotypes, namely M, MLSBconstitutive and MLSBinducible respectively. The last report of resistance in Chile was done in the period 1990-1998, in which resistance to macrolides was 5.4%, with M phenotype as the predominant one. Aim: To characterize the evolution of erythromycin and clindamycin resistance and their associated genes in S. pyogenes strains isolated from patients with invasive and noninvasive infections in the period 1996 to 2005. Material and Methods: Resistance to erythromycin and clindamycin was determined in 1,282 clinical isolates using the disk diffusion test. Resistant isolates were analyzed by polymerase chain reaction (PCR) for the presence of the above mentioned resistance genes. Results: Global resistance to erythromycin and clindamycin was 3.5 and 0.7% respectively. Eighty percent of the resistant strains possessed the M. phenotype. Conclusions: Resistance levels of S. pyogenes have decreased in Chile in the last years. Most resistant strains have M phenotype in contrast to many countries in which the MLSB constitutive phenotype is the predominant one.
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    Clinical Presentation and Perioperative Management of Pheochromocytomas and Paragangliomas: A 4-Decade Experience
    (ENDOCRINE SOC, 2021) Uslar, Thomas; San Francisco, Ignacio F.; Olmos, Roberto; Macchiavelo, Stefano; Zuniga, Alvaro; Rojas, Pablo; Garrido, Marcelo; Huete, Alvaro; Mendez, Gonzalo P.; Cortinez, Ignacio; Zemelman, Jose Tomas; Cifuentes, Joaquin; Castro, Fernando; Olivari, Daniela; Dominguez, Jose Miguel; Arteaga, Eugenio; Fardella, Carlos E.; Valdes, Gloria; Tagle, Rodrigo; Baudrand, Rene
    Purpose: Latin American reports on pheochromocytomas and paragangliomas (PPGLs) are scarce. Recent studies demonstrate changes in clinical presentation and management of these patients. Herein, we assessed the main characteristics of PPGL patients in our academic center over the past 4 decades.
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    Covariation of taxonomic and functional facets of β-diversity in Chilean freshwater fish assemblages: Implications for current and future processes of biotic homogenization
    (2023) Castro, Sergio A.; Rojas, Pablo; Vila, Irma; Jaksic, Fabian M.
    The biodiversity of assemblages that experience the introduction and extinction of species may lead to responses in two important facets: The taxonomic and functional diversity. The way in which these facets are associated may reveal important implications and consequences for the conservation of those assemblages. Considering the critical situation of freshwater fishes in continental Chile (30 degrees - 56 degrees S), we analyzed how the taxonomic (TD beta) and functional (FD beta) facets of beta-diversity, and their components of turnover and nestedness, are associated. We evaluated changes in beta-diversity (Delta TD beta and Delta FD beta), turnover (Delta TDtur and Delta FDtur), and nestedness (Delta TDnes and Delta FDnes) in 20 fish assemblages from their historical (pre-European) to current composition. We also simulated future trends of these changes, assuming that native species with conservation issues would become extinct. Our results show that the fish assemblages studied are in a process of loss of beta-diversity, both in taxonomic and functional facets (Delta TD beta = -3.9%; Delta FD beta = -30.4%); also, that these facets are positively correlated in the assemblages studied (r = 0.617; P < 0.05). Both components showed by loss in nestedness (Delta TDnes = -36.9%; Delta FDnes = -60.9%) but gain in turnover (Delta TDtur = 9.2%; Delta FDtur = 12.3%). The functional beta-diversity decreased more than the taxonomic (Delta FD beta > Delta TD beta), which was caused chiefly by six exotic species of Salmonidae, whose geographical spread was wider and that at the same time shared several morpho-functional traits. Our forecasts, assuming an intensification in the extinction of Endangered and Vulnerable native species, indicate that the process of homogenization will continue, though at a lower rate. Our study shows that the freshwater ichthyofauna of continental Chile is undergoing biotic homogenization, and that this process involves the facets of taxonomic and functional beta-diversity, which are show high correlation between historical and current compositions. Both facets show that process is influenced by nestedness, and while turnover contributes to differentiation (both taxonomic and functional), its importance is overshadowed by nestedness.
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    Differential response of the components of functional diversity in Orestias fishes (Cyprinodontidae) of the High Andean Plateau
    (2024) Rojas, Pablo; Castro, Sergio A.; Vila, Irma; Jaksic, Fabian M.
    Orestias (Cyprinodontiformes, Cyprinodontidae) is a diverse genus of freshwater fish endemic to the high Andean plateau (Altiplano) of the Andes Mountains, South America. Within the Altiplano, Orestias species form assemblages of varying taxonomic richness, exhibiting considerable diversity in morphological forms and sizes, and occupying different habitat types. Here, we investigate the functional diversity of Orestias assemblages in two basins within the Altiplano: Titicaca Lake and the southwestern Altiplano basins. Titicaca Lake is characterized by high species diversity that evolved sympatrically, while the southwestern Altiplano has lower species diversity that evolved allopatrically. Given that taxonomic diversity under sympatric conditions can promote greater functional diversity, we hypothesize that the Titicaca assemblage should display higher indicators of functional diversity. By using traits related to locomotion, food acquisition, and habitat type to quantify functional diversity we used four functional diversity indicators (functional richness, divergence, specialization, and originality) to compare the Orestias assemblages in two basins. We found no difference in functional divergence and originality between the Orestias from two basins. However, functional specialization was higher in the southwestern Altiplano, contrary to our hypothesis. Only functional richness was higher Titicaca assemblage; supporting our hypothesis. The differentiation between assemblages arises primarily from traits associated with locomotion and food acquisition. Several Orestias species are considered endangered and the extinction of any these taxa could impact the functional diversity of these basins.
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    Exotic species elicit decoupled responses in functional diversity components of freshwater fish assemblages in Chile
    (2021) Rojas, Pablo; Castro, Sergio A.; Vila, Irma; Jaksic, Fabian M.
    In the freshwater basins of central Chile, 28 exotic species have been introduced, which have contributed to increase taxonomic diversity. Nevertheless, how these species have modified the components of functional diversity in these assemblages, a key aspect in learning about their present and future stability within an ecosystem, is unknown. In this study, we analyzed how the introduction of exotic species affects the functional diversity components of richness (FRic), divergence (FDiv), specialization (FSpe), and functional originality (FOri). Additionally, we simulated the effect of the loss (extinction/extirpation) of threatened native species. To do so, we gathered information on the distribution and functional characters of native and exotic species. Through Principal Coordinates Analysis (PCo), we obtained three independent axes (PCoA1, PCoA2, and PCoA3), which allowed us to define a multidimensional space and then to calculate FRic, FDiv, FSpe, and FOri. Our results indicate that richness and functional originality have increased significantly with the introduction of exotic species (263% and 32%, respectively). In contrast, functional divergence and specialization have remained the same. The possible extinction of threatened native species may promote increases in functional originality, decreases in functional richness and divergence, and unchanged functional specialization. On the other hand, a subset of exotic species presents novel features, while another shows redundant features with native ichthyofauna. We emphasize that the possible extinction of native species currently classified as threatened may lead to the disappearance of unique functional groups, which puts at risk the persistence and stability of these assemblages.
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    Hidrogenera Salvador : (re) creación del paisaje productivo, División El Salvador, Chile
    (2020) Rojas, Pablo; García Alfonso, Pilar; Scheidegger Alvarado, Arturo; García Partarrieu, Ignacio; Pontificia Universidad Católica de Chile. Escuela de Arquitectura
    Las Energías Renovables (ER) son tecnologías que prometen ser generadoras de grandes cambios a nivel medioambiental. Utilizando dispositivos para la transformación de recursos presentes en el viento, el sol, el agua o la tierra; estos generan un impacto más allá de su bonanza climática, posibilitando cambios espaciales, sociales y económicos en la vida humana. El hidrógeno renovable corresponde a una de estas, utilizada desde el siglo pasado para viajar al espacio, pretende fomentar su uso actualmente en Chile y el mundo para suplir el uso de combustibles fósiles, altamente contaminantes. Dado su potencial territorial, el H2 tiene un especial énfasis de su desarrollo en el Desierto de Atacama. Dentro de éste, la ciudad de El Salvador posee particulares características en su territorio, teniendo uno de los niveles más altos de radiación en la región y el planeta , presentado precipitaciones y nieve en ciertas épocas del año, que de manera intermitente, son causantes de grandes catástrofes, como el aluvión ocurrido el 2015, afectando a toda la provincia de Chañaral y el norte de Chile La localidad corresponde a un campamento residencial minero creado para la extracción de cobre en 1959, actualmente propiedad de CODELCO, empresa que se encuentra en la construcción un nuevo yacimiento en la división, dejando en desuso y abandono gran parte de la zona explotada. Es así, como ante el inminente desarrollo de las tecnologías del hidrógeno, en conjunto a la presencia de recursos hídrícos y solares en El Salvador, se busca la creación de un proyecto de arquitectura que catalice los recursos naturales locales para el impulso de esta nueva industria, promoviendo la diversificación de las actividades productivas, como también, dándole un uso público al territorio minero , posibilitando la creación de un atractivo turístico a partir de la interacción entre dispositivos, infraestructura y paisaje.
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    Recreation, Free Time and Well-Being According to Children and Adolescents in Chile: Mediator Meanings of Satisfaction
    (2018) Ramírez, Lorena; Alfaro, Jaime; Heine Preisler, Pauline; Easton, Patricia; Urzúa, Gabriel; Amo, Blanca; Valdebenito, Francisca; Rojas, Pablo; Monreal Álvarez, María Verónica; Jaramillo, Andrea
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    The physiognomic and the geometrical apprehensions of metaphor
    (2013) Cornejo Alarcón, Carlos; Rojas, Pablo; Olivares, Himmbler