Browsing by Author "Valenzuela, Sebastian"

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    A Panel Study on the Dynamics of Social Media Use and Conspiracy Thinking
    (SPRINGER INTERNATIONAL PUBLISHING AG, 2023) Valenzuela, Sebastian; Diehl, Trevor; Lee, Sangwon; Halpern, Daniel
    Studies exploring the association between social media use and belief in conspiracy theories have yielded mixed evidence. To address this inconsistency, we focus on conspiracy thinking - a predisposition to interpret events as products of secret, malevolent plots - for which contextual confounds can be better isolated. We posit that social media use and conspiracy thinking are positively related, and examine whether this relationship stems from selectivity effects, media effects, or reinforcing effects. The analysis relies on a random intercept cross-lagged panel model estimated with data from an original three-wave panel survey (N = 331) fielded in Chile. Results support the existence of a reciprocal, lagged relationship between frequency of use of social media platforms, and conspiracy thinking. In line with recent studies on social media, the association becomes manifest at the within-, rather than between-, person level. We close with a discussion of how these results align with the reinforcing spirals model.
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    Corruption and Political Knowledge Erosion. A Cautionary Tale from Latin America
    (OXFORD UNIV PRESS, 2022) Bargsted, Matias; Bachmann, Ingrid; Valenzuela, Sebastian
    Previous research has shown that corruption diminishes citizens' level of political support and engagement. We extend this line of reasoning and evaluate whether previous levels of perceived corruption can influence subsequent levels of political knowledge. We test this proposition with data from a two-wave panel probability survey applied in Chile between 2016 and 2017, just after a 2-year period in which an avalanche of corruption scandals shook the country. Our estimates confirm that perceived corruption reduces subsequent political knowledge, while controlling for prior knowledge. This pattern is particularly strong among non-ideologues and people ideologically distant from the incumbent government. Given the status of political knowledge as a democratically valuable trait, our results uncover some normatively disturbing consequences of corruption.
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    Targeting antisense mitochondrial ncRNAs inhibits murine melanoma tumor growth and metastasis through reduction in survival and invasion factors
    (IMPACT JOURNALS LLC, 2016) Lobos Gonzalez, Lorena; Silva, Veronica; Araya, Mariela; Restovic, Franko; Echenique, Javiera; Oliveira Cruz, Luciana; Fitzpatrick, Christopher; Briones, Macarena; Villegas, Jaime; Villota, Claudio; Vidaurre, Soledad; Borgna, Vincenzo; Socias, Miguel; Valenzuela, Sebastian; Lopez, Constanza; Socias, Teresa; Varas, Manuel; Diaz, Jorge; Burzio, Luis O.; Burzio, Veronica A.
    We reported that knockdown of the antisense noncoding mitochondrial RNAs (ASncmtRNAs) induces apoptotic death of several human tumor cell lines, but not normal cells, suggesting this approach for selective therapy against different types of cancer. In order to translate these results to a preclinical scenario, we characterized the murine noncoding mitochondrial RNAs (ncmtRNAs) and performed in vivo knockdown in syngeneic murine melanoma models. Mouse ncmtRNAs display structures similar to the human counterparts, including long double-stranded regions arising from the presence of inverted repeats. Knockdown of ASncmtRNAs with specific antisense oligonucleotides (ASO) reduces murine melanoma B16F10 cell proliferation and induces apoptosis in vitro through downregulation of pro-survival and metastasis markers, particularly survivin. For in vivo studies, subcutaneous B16F10 melanoma tumors in C57BL/6 mice were treated systemically with specific and control antisense oligonucleotides (ASO). For metastasis studies, tumors were resected, followed by systemic administration of ASOs and the presence of metastatic nodules in lungs and liver was assessed. Treatment with specific ASO inhibited tumor growth and metastasis after primary tumor resection. In a metastasis-only assay, mice inoculated intravenously with cells and treated with the same ASO displayed reduced number and size of melanoma nodules in the lungs, compared to controls. Our results suggest that ASncmtRNAs could be potent targets for melanoma therapy. To our knowledge, the ASncmtRNAs are the first potential non-nuclear targets for melanoma therapy.