Examinando por Autor "Fuentes, Juan"

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    Effect of Terminal Groups of Dendrimers in the Complexation with Antisense Oligonucleotides and Cell Uptake
    (SPRINGER, 2016-02) Márquez-Miranda, Valeria; Peñaloza, Juan Pablo; Araya-Durán, Ingrid; Reyes, Rodrigo; Vidaurre, Soledad; Romero, Valentina; Fuentes, Juan; Céric, Francisco; Velásquez, Luis; González-Nilo, Fernando D.; Otero, Carolina
    Poly(amidoamine) dendrimers are the most recognized class of dendrimer. Amino-terminated (PAMAM-NH2) and hydroxyl-terminated (PAMAM-OH) dendrimers of generation 4 are widely used, since they are commercially available. Both have different properties, mainly based on their different overall charges at physiological pH. Currently, an important function of dendrimers as carriers of short single-stranded DNA has been applied. These molecules, known as antisense oligonucleotides (asODNs), are able to inhibit the expression of a target mRNA. Whereas PAMAM-NH2 dendrimers have shown to be able to transfect plasmid DNA, PAMAM-OH dendrimers have not shown the same successful results. However, little is known about their interaction with shorter and more flexible molecules such as asODNs. Due to several initiatives, the use of these neutral dendrimers as a scaffold to introduce other functional groups has been proposed. Because of its low cytotoxicity, it is relevant to understand the molecular phenomena involving these types of dendrimers. In this work, we studied the behavior of an antisense oligonucleotide in presence of both types of dendrimers using molecular dynamics simulations, in order to elucidate if they are able to form stable complexes. In this manner, we demonstrated at atomic level that PAMAM-NH2, unlike PAMAM-OH, could form a well-compacted complex with asODN, albeit PAMAM-OH can also establish stable interactions with the oligonucleotide. The biological activity of asODN in complex with PAMAM-NH2 dendrimer was also shown. Finally, we revealed that in contact with PAMAM-OH, asODN remains outside the cells as TIRF microscopy results showed, due to its poor interaction with this dendrimer and cell membranes.
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    Imagen corporal y autoestima en niños según su estado nutricional y frecuencia de actividad física
    (Sociedad Chilena de Nutricion Bromatologia y Toxilogica, 2017-03) Delgado-Floody, Pedro; Caamaño, Felipe; Osorio, Aldo; Jerez, Daniel; Fuentes, Juan; Levin, Eduardo; Tapia, Juan
    La actividad física juega un papel importante en el desarrollo de los niños. El propósito de este estudio fue comparar según estado nutricional y frecuencia de actividad física la imagen corporal, autoestima, riesgo cardio-metabólico y rendimiento físico de niños. Se estudió 208 niños de 11,9±1,2 años de edad, 115 hombres y 93 mujeres. Quedaron divididos según frecuencia de actividad física a la semana: El Grupo 1 (n= 87) no realizan; Grupo 2 (n= 64) realizan 1 o 2 veces/semana; Grupo 3 (n= 57), realizan 3 o 4 veces/semana. Se observó que 51 niños presentaron sobrepeso y 40 de ellos obesidad. Los niños que realizan 3 o 4 veces actividad física/semana, presentaron menor preocupación por su imagen corporal y puntajes superiores en autoestima, ambas con significancia estadística (p<0,05), además reportaron menor riesgo cardio-metabólico y mejor rendimiento físico. Se concluye que los niños con mayor frecuencia de actividad física/semana, evidencian beneficios en su desarrollo integral.
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    The RNA Chaperone Hfq Participates in Persistence to Multiple Antibiotics in the Fish Pathogen Yersinia ruckeri
    (MDPI AG, 2021-06) Calderón, Iván; Barros, María José; Montt, Fernanda; Gil, Fernando; Fuentes, Juan; Acuña, Lillian
    Yersinia ruckeri causes outbreaks of enteric redmouth disease in salmon aquaculture all over the world. The transient antibiotic tolerance exhibited by bacterial persisters is commonly thought to be responsible for outbreaks; however, the molecular factors underlying this behavior have not been explored in Y. ruckeri. In this study, we investigated the participation of the RNA chaperone Hfq from Y. ruckeri in antibiotic persistence. Cultures of the hfq-knockout mutant (∆hfq) exhibited faster replication, increased ATP levels and a more reductive environment than the wild type. The growth curves of bacteria exposed to sublethal concentrations of ampicillin, oxolinic acid, ciprofloxacin and polymyxin B revealed a greater susceptibility for the ∆hfq strain. The time-kill curves of bacteria treated with the antibiotics mentioned above and florfenicol, using inoculums from exponential, stationary and biofilm cultures, demonstrated that the ∆hfq strain has significant defects in persister cells production. To shed more light on the role of Hfq in antibiotic persistence, we analyzed its dependence on the (p)ppGpp synthetase RelA by determining the persister cells production in the absence of the relA gene. The ∆relA and ∆relA∆hfq strains displayed similar defects in persister cells formation, but higher than ∆hfq strain. Similarly, stationary cultures of the ∆relA and ∆relA∆hfq strains exhibited comparable levels of ATP but higher than that of the ∆hfq strain, indicating that relA is epistatic over hfq. Taken together, our findings provide valuable information on antibiotic persistence in Y. ruckeri, shedding light on the participation of Hfq in the persistence phenomenon. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.