Browsing by Author "Varela, Diego"

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    Excessive release of inorganic polyphosphate by ALS/FTD astrocytes causes non-cell-autonomous toxicity to motoneurons
    (2022) Arredondo, Cristian; Cefaliello, Carolina; Dyrda, Agnieszka; Jury, Nur; Martinez, Pablo; Diaz, Ivan; Amaro, Armando; Tran, Helene; Morales, Danna; Pertusa, Maria; Stoica, Lorelei; Fritz, Elsa; Corvalan, Daniela; Abarzua, Sebastian; Mendez-Ruette, Maxs; Fernandez, Paola; Rojas, Fabiola; Kumar, Meenakshi Sundaram; Aguilar, Rodrigo; Almeida, Sandra; Weiss, Alexandra; Bustos, Fernando J.; Gonzalez-Nilo, Fernando; Otero, Carolina; Tevy, Maria Florencia; Bosco, Daryl A.; Saez, Juan C.; Kahne, Thilo; Gao, Fen-Biao; Berry, James D.; Nicholson, Katharine; Sena-Esteves, Miguel; Madrid, Rodolfo; Varela, Diego; Montecino, Martin; Brown, Robert H.; van Zundert, Brigitte
    Non-cell-autonomous mechanisms contribute to neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), in which astrocytes release unidentified factors that are toxic to motoneurons (MNs). We report here that mouse and patient iPSC-derived astrocytes with diverse ALS/FTD-linked mutations (SOD1, TARDBP, and C9ORF72) display elevated levels of intracellular inorganic polyphosphate (polyP), a ubiquitous, negatively charged biopolymer. PolyP levels are also increased in astrocyte-conditioned media (ACM) from ALS/FTD astrocytes. ACM-mediated MN death is prevented by degrading or neutralizing polyP in ALS/FTD astrocytes or ACM. Studies further reveal that postmortem familial and sporadic ALS spinal cord sections display enriched polyP staining signals and that ALS cerebrospinal fluid (CSF) exhibits increased polyP concentrations. Our in vitro results establish excessive astrocyte-derived polyP as a critical factor in non-cell-autonomous MN degeneration and a potential therapeutic target for ALS/ FTD. The CSF data indicate that polyP might serve as a new biomarker for ALS/FTD.
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    In Vivo and in vitro antitumor activity of tomatine in hepatocellular carcinoma
    (2022) Echeverria, Cesar; Martin, Aldo; Simon, Felipe; Salas, Cristian O.; Nazal, Mariajesus; Varela, Diego; Perez-Castro, Ramon A.; Santibanez, Juan F.; Valdes-Valdes, Ricardo O.; Forero-Doria, Oscar; Echeverria, Javier
    Background: There is abundant ethnopharmacological evidence the uses of regarding Solanum species as antitumor and anticancer agents. Glycoalkaloids are among the molecules with antiproliferative activity reported in these species. Purpose: To evaluate the anticancer effect of the Solanum glycoalkaloid tomatine in hepatocellular carcinoma (HCC) in vitro (HepG2 cells) and in vivo models. Methods: The resazurin reduction assay was performed to detect the effect of tomatine on cell viability in human HepG2 cell lines. Programmed cell death was investigated by means of cellular apoptosis assays using Annexin V. The expression of cancer related proteins was detected by Western blotting (WB). Reactive oxygen species (ROS) and calcium were determined by 2,7-dichlorodihydrofluorescein diacetate and Fluo-4, respectively. Intrahepatic HepG2 xenograft mouse model was used to elucidate the effect of tomatine on tumor growth in vivo. Results and Discussion: Tomatine reduced HepG2 cell viability and induced the early apoptosis phase of cell death, consistently with caspase-3, -7, Bcl-2 family, and P53 proteins activation. Furthermore, tomatine increased intracellular ROS and cytosolic Ca+2 levels. Moreover, the NSG mouse xenograft model showed that treating mice with tomatine inhibited HepG2 tumor growth. Conclusion: Tomatine inhibits in vitro and in vivo HCC tumorigenesis in part via modulation of p53, Ca+2, and ROS signalling. Thus, the results suggest the potential cancer therapeutic use of tomatine in HCC patients.
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    Increases in reactive oxygen species enhance vascular endothelial cell migration through a mechanism dependent on the transient receptor potential melastatin 4 ion channel
    (2015) Sarmiento, Daniela; Montorfano, Ignacio; Cerda, Oscar; Caceres, Monica; Becerra, Alvaro; Cabello-Verrugio, Claudio; Elorza, Alvaro A.; Riedel, Claudia; Tapia, Pablo; Velasquez, Luis A.; Varela, Diego; Simon, Felipe
    A hallmark of severe inflammation is reactive oxygen species (ROS) overproduction induced by increased inflammatory mediators secretion. During systemic inflammation, inflammation mediators circulating in the bloodstream interact with endothelial cells (ECs) raising intracellular oxidative stress at the endothelial monolayer. Oxidative stress mediates several pathological functions, including an exacerbated EC migration. Because cell migration critically depends on calcium channel-mediated Ca2+ influx, the molecular identification of the calcium channel involved in oxidative stress-modulated EC migration has been the subject of intense investigation.
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    Preventive leptin administration protects against sepsis through improving hypotension, tachycardia, oxidative stress burst, multiple organ dysfunction, and increasing survival
    (2018) Vallejos, Alejandro; Olivares, Pedro; Varela, Diego; Echeverria, Cesar; Cabello Verrugio, Claudio Alejandro; Pérez Leighton, Claudio; Simon, Felipe
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    VICTOR VECTORS @ DIPROMATS 2024: Propaganda Detection with LLM Paraphrasing and Machine Translation
    (CEUR-WS, 2024) Fernández, Miguel; Ojeda Aguila, Maximiliano Eduardo; Guevara, Lilly; Varela, Diego; Mendoza Rocha, Marcelo Gabriel; Barrón-Cedeno, Alberto
    Identifying propaganda in social media posts is an important task that can help to better understand the strategies applied by policy makers and stake holders when trying to convey their message to the general public. We describe our participation in DIPROMATS 2024 Task 1 on the automated detection and characterization of propaganda techniques and narratives from diplomats of major powers. We show an efficient way to utilize Large Language Models (LLMs) to paraphrase a sample of the training instances, to balance the class distribution in the datasets provided by the shared task. Our submission ranked 1st in Subtask-1a in English (ICM score of 0.2123) and 1st in the bilingual evaluation (ICM score of 0.2048). We also achieved top-3 rankings in Spanish and subtasks 1b and 1c.