Browsing by Author "Rojas, Daniela"

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    Creencias de formadores de profesores de matemática sobre resolución de problema
    (2016) Chandia, Eugenio; Rojas, Daniela; Rojas Sateler, Francisco; Howard, Sebastián
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    Modulation of the Acute Inflammatory Response Induced by the Escherichia coli Lipopolysaccharide through the Interaction of Pentoxifylline and Florfenicol in a Rabbit Model
    (2023) Cazanga, Victoria; Palma, Cristina; Casanova, Tomas; Rojas, Daniela; Barrera, Karin; Valenzuela, Cristhian; Acevedo, Aracelly; Ascui-Gac, Gabriel; Perez-Jeldres, Tamara; Perez-Fernandez, Ruben
    Background: Experimental reports have demonstrated that florfenicol (FFC) exerts potent anti-inflammatory effects, improving survival in a murine endotoxemia model. Considering the anti-inflammatory and immunomodulatory properties of pentoxifylline (PTX) as an adjuvant to enhance the efficacy of antibiotics, the anti-inflammatory effects of the interaction FFC/PTX over the E. coli Lipopolysaccharide (LPS)-induced acute inflammatory response was evaluated in rabbits. Methods: Twenty-five clinically healthy New Zealand rabbits (3.8 +/- 0.2 kg body weight: bw), were distributed into five experimental groups. Group 1 (control): treated with 1 mL/4 kg bw of 0.9% saline solution (SS) intravenously (IV). Group 2 (LPS): treated with an IV dose of 5 mu g/kg of LPS. Group 3 (pentoxifylline (PTX) + LPS): treated with an oral dose of 30 mg/kg PTX, followed by an IV dose of 5 mu g/kg of LPS 45 min after PTX. Group 4 (Florfenicol (FFC) + LPS): treated with an IM dose of 20 mg/kg of FFC, followed by an IV dose of 5 mu g/kg of LPS 45 min after FFC administration. Group 5 (PTX + FFC + LPS): treated with an oral dose of 30 mg/kg of PTX, followed by an IM dose of 20 mg/kg of FFC, and, 45 min after an IV dose of 5 mu g/kg of LPS was administered. The anti-inflammatory response was evaluated through changes in plasma levels of interleukins (TNF-alpha, IL-1 beta and IL-6), C-reactive protein (CRP), and body temperature. Results: It has been shown that each drug produced a partial inhibition over the LPS-induced increase in TNF-alpha, IL-1 beta, and CRP. When both drugs were co-administered, a synergistic inhibitory effect on the IL-1 beta and CRP plasma concentrations was observed, associated with a synergic antipyretic effect. However, the co-administration of PTX/FFC failed to modify the LPS-induced increase in the TNF-alpha plasma concentrations. Conclusions: We concluded that the combination of FFC and PTX in our LPS sepsis models demonstrates immunomodulatory effects. An apparent synergistic effect was observed for the IL-1 beta inhibition, which peaks at three hours and then decreases. At the same time, each drug alone was superior in reducing TNF-alpha levels, while the combination was inferior. However, the peak of TNF-alpha in this sepsis model was at 12 h. Therefore, in rabbits plasma IL-1 beta and TNF-alpha could be regulated independently, thus, further research is needed to explore the effects of this combination over a more prolonged period.
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    Ubiquitous influenza A virus in Chilean swine before the H1N1pdm09 introduction
    (2021) Mena, Juan; Ariyama, Naomi; Navarro, Camila; Quezada, Manuel; Brevis, Cristina; Rojas, Daniela; Medina, Rafael A.; Brito, Barbara; Ruiz, Alvaro; Neira, Victor
    Influenza A virus (IAV) was a neglected swine pathogen in South America before the 2009 H1N1 pandemic (A(H1N1)pdm2009). The A(H1N1)pdm2009 strain has widely spread among the Chilean swine population and co-circulates with endemic H1N2 and H3N2 viruses. The presence of IAV as a swine pathogen in Chilean swine before the 2009 pandemic is unknown. To understand the IAV in swine prior to 2009, aY retrospective study of samples from pigs affected with respiratory diseases was conducted. Ninety formalin-fixed and paraffin-embedded lung tissues belonging to 21 intensive pig production companies located in five different administrative regions of Chile, collected between 2005 and 2008, were evaluated. The tissues were tested by immunohistochemistry (IHC), identifying that 9 out of 21 farms (42.8%) and 31 out of 90 (34.4%) samples were IAV positive. Only three out of the 31 IHC-positive samples were positive upon RNA extraction and rtRT-PCR analysis. Partial nucleotide sequences were obtained from one sample and characterized as an H3N2 subtype closely related to a human seasonal H3N2 IAVs that circulated globally in the mid-90s. These results indicate that IAV was circulating in swine before 2009 and highlight the value of conducting retrospective studies through genomic strategies to analyse historical samples.
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