Browsing by Author "Reyes, Pablo"
Now showing 1 - 7 of 7
Results Per Page
Sort Options
Publication Educational disparities in brain health and dementia across Latin America and the United States(2024) Gonzalez, Raul; Legaz, Agustina; Moguilner, Sebastián; Cruzat, Josephine; Hernández, Hernán; Baez, Sandra; Cocchi, Rafael; Coronel, Carlos; Medel,Vicente; Tagliazuchi, Enzo; Migeot, Joaquín; Ochoa, Carolina; Maito, Marcelo; Reyes, Pablo; Santamaria, Hernando; Godoy, Maria; Javande, Shireen; García, Adolfo; Matallana, Diana; Avila, José; Slachevsky Chonchol, Andrea; Behrens, María; Custodio, Nilton; Cardona, Juan; Brusco, Ignacio; Bruno, Martín; Sosa, Ana; Pina, Stefanie; Takada, Leonel; França, Elisa; Valcour, Victor; Possin, Katherine; De Oliveira, Maira; Lopera, Francisco; Lawlor, Brian; Hu, Kun; Miller, Bruce; Yokoyama, Jennifer; Gonzalez, Cecilia; Ibañez, AgustinBackground: Education influences brain health and dementia. However, its impact across regions, specifically Latin America (LA) and the United States (US), is unknown. Methods: A total of 1412 participants comprising controls, patients with Alzheimer's disease (AD), and frontotemporal lobar degeneration (FTLD) from LA and the US were included. We studied the association of education with brain volume and functional connectivity while controlling for imaging quality and variability, age, sex, total intracranial volume (TIV), and recording type. Results: Education influenced brain measures, explaining 24%-98% of the geographical differences. The educational disparities between LA and the US were associated with gray matter volume and connectivity variations, especially in LA and AD patients. Education emerged as a critical factor in classifying aging and dementia across regions. Discussion: The results underscore the impact of education on brain structure and function in LA, highlighting the importance of incorporating educational factors into diagnosing, care, and prevention, and emphasizing the need for global diversity in research. Highlights: Lower education was linked to reduced brain volume and connectivity in healthy controls (HCs), Alzheimer's disease (AD), and frontotemporal lobar degeneration (FTLD). Latin American cohorts have lower educational levels compared to the those in the United States. Educational disparities majorly drive brain health differences between regions. Educational differences were significant in both conditions, but more in AD than FTLD. Education stands as a critical factor in classifying aging and dementia across regions.Item Evaluating the reliability of neurocognitive biomarkers of neurodegenerative diseases across countries: A machine learning approach(2020) Bachli, M. Belen; Sedeno, Lucas; Ochab, Jeremi K.; Piguet, Olivier; Kumfor, Fiona; Reyes, Pablo; Torralva, Teresa; Roca, María; Cardona, Juan Felipe; Gonzalez Campo, Cecilia; Herrera, Eduar; Slachevsky, Andrea; Matallana, Diana; Manes, Facundo; García, Adolfo M.; Ibanez, Agustín; Chialvo, Dante R.Accurate early diagnosis of neurodegenerative diseases represents a growing challenge for current clinical practice. Promisingly, current tools can be complemented by computational decision-support methods to objectively analyze multidimensional measures and increase diagnostic confidence. Yet, widespread application of these tools cannot be recommended unless they are proven to perform consistently and reproducibly across samples from different countries. We implemented machine-learning algorithms to evaluate the prediction power of neurocognitive biomarkers (behavioral and imaging measures) for classifying two neurodegenerative conditions –Alzheimer Disease (AD) and behavioral variant frontotemporal dementia (bvFTD)– across three different countries (>200 participants). We use machine-learning tools integrating multimodal measures such as cognitive scores (executive functions and cognitive screening) and brain atrophy volume (voxel based morphometry from fronto-temporo-insular regions in bvFTD, and temporo-parietal regions in AD) to identify the most relevant features in predicting the incidence of the diseases. In the Country-1 cohort, predictions of AD and bvFTD became maximally improved upon inclusion of cognitive screenings outcomes combined with atrophy levels. Multimodal training data from this cohort allowed predicting both AD and bvFTD in the other two novel datasets from other countries with high accuracy (>90%), demonstrating the robustness of the approach as well as the differential specificity and reliability of behavioral and neural markers for each condition. In sum, this is the first study, across centers and countries, to validate the predictive power of cognitive signatures combined with atrophy levels for contrastive neurodegenerative conditions, validating a benchmark for future assessments of reliability and reproducibilityItem Factores Asociados al Autoestigma de la Depresión en Adolescentes en Santiago, Chile.(2021) Suárez-Barba, Mariela Alexandra; Reyes, Pablo; Pérez Ewert, J. Carola; Martínez, VaniaResumen. Objetivo: Determinar la asociación entre autoestigma de la depresión y factores sociodemográficos, historia personal y parental de depresión, sintomatología ansiosa y depresiva, y calidad de vida en adolescentes. Método: Estudio transversal correlacional, en una muestra de 192 adolescentes (8º básico a 3º medio) de tres colegios particulares subvencionados de Santiago, Chile, se aplicaron cuestionarios de factores sociodemográficos, autoestigma de la depresión, sintomatología ansiosa y depresiva, y calidad de vida. Los datos se analizaron con prueba t de Student, ANOVA, coeficiente de Pearson y Regresión Lineal. Resultados: No hubo diferencias en autoestigma de depresión entre hombres y mujeres. Fue mayor el autoestigma de la depresión en adolescentes que sospechaban que habían tenido o tenían depresión, referían que su madre o padre habían tenido depresión, tenían mayor sintomatología depresiva y/o ansiosa y menor calidad de vida. Conclusión: La presencia de depresión en los progenitores progenitores (madre y/o padre), así como el desconocimiento de los adolescentes respecto a si ellos presentan el cuadro clínico, se relaciona con mayor autoestigma de la depresión en los adolescentes, lo que inhibe la búsqueda de ayuda.Item Immunosensory signaling by carotid body chemoreceptors(2011) Zapata, Patricio; Larraín, Carolina; Reyes, Pablo; Fernández, RicardoInjections of lipopolysaccharide (LPS) have been used to produce the signs of sepsis and study their underlying mechanisms. Intravenous (IV) injections of LPS in anesthetized cats induce tachypnea, tachycardia and hypotension, but ventilatory changes are suppressed after sectioning carotid and aortic nerves. Otherwise. LPS increases the basal frequency of carotid chemosensory discharges, but reduces ventilatory and chemosensory responses to hypoxia and nicotine injections. Increases in cytokines (IL-1 beta, IL-6 and TNF-alpha) are observed in plasma and tissues after injecting LPS. In carotid bodies perfused in vitro. TNF-alpha reduces chemosensory discharges induced by hypoxia. The rat carotid body and its sensory ganglion constitutively express LPS canonical receptor. TLR4, as well as TNF-alpha and its receptors (TNF-R1 and TNF-R2). Increases of TNF-alpha and TNF-R2 expression occur after LPS administration. The activation of peripheral and central autonomic pathways induced by LPS or IL's is partly dependent on intact vagus nerves. Thus, the carotid and vagus nerves provide routes between the immune system and CNS structures involved in systemic inflammatory responses. (C) 2011 Elsevier B.V. All rights reserved.Item Mechanical and Antimicrobial Polyethylene Composites with CaO Nanoparticles(2020) Silva, Cristián; Bobillier, Felipe; Canales, Daniel; Sepúlveda, Francesca Antonella; Cament, Alejandro; Amigo, Nicolás; Rivas, Lina; Ulloa, María T.; Reyes, Pablo; Ortiz, J. Andrés; Gómez, Tatiana; Loyo, Carlos; Zapata, Paula ALow-density polyethylene composites containing different sizes of calcium oxide (CaO) nanoparticles were obtained by melt mixing. The CaO nanoparticles were synthesized by either the sol-gel or sonication methods, obtaining two different sizes: ca. 55 nm and 25 nm. These nanoparticles were used either as-synthesized or were modified organically on the surface with oleic acid (Mod-CaO), at concentrations of 3, 5, and 10 wt% in the polymer. The Mod-CaO nanoparticles of 25 nm can act as nucleating agents, increasing the polymer’s crystallinity. The Young’s Modulus increased with the Mod-CaO nanoparticles, rendering higher reinforcement effects with an increase as high as 36%. The reduction in Escherichia coli bacteria in the nanocomposites increased with the amount of CaO nanoparticles, the size reduction, and the surface modification. The highest antimicrobial behavior was found in the composites with a Mod-CaO of 25 nm, presenting a reduction of 99.99%. This strong antimicrobial effect can be associated with the release of the Ca2+ from the composites, as studied for the composite with 10 wt% nanoparticles. The ion release was dependent on the size of the nanoparticles and their surface modification. These findings show that CaO nanoparticles are an excellent alternative as an antimicrobial filler in polymer nanocomposites to be applied for food packaging or medical devices.Publication Multi-feature computational framework for combined signatures of dementia in underrepresented settings(2022) Moguilner, Sebastián; Birba, Agustina; Fittipaldi, Sol; Gonzalez, Cecilia; Tagliazucchi, Enzo; Reyes, Pablo; Matallana, Diana; Parra, Mario; Slachevsky Chonchol, Andrea; Farías, Gonzalo; Cruzat, Josefina; García, Adolfo; Eyre, Harris; La Joie, Renaud; Rabinovici, Gil; Whelan, Robert; Ibáñez, AgustínObjective.The differential diagnosis of behavioral variant frontotemporal dementia (bvFTD) and Alzheimer's disease (AD) remains challenging in underrepresented, underdiagnosed groups, including Latinos, as advanced biomarkers are rarely available. Recent guidelines for the study of dementia highlight the critical role of biomarkers. Thus, novel cost-effective complementary approaches are required in clinical settings.Approach. We developed a novel framework based on a gradient boosting machine learning classifier, tuned by Bayesian optimization, on a multi-feature multimodal approach (combining demographic, neuropsychological, magnetic resonance imaging (MRI), and electroencephalography/functional MRI connectivity data) to characterize neurodegeneration using site harmonization and sequential feature selection. We assessed 54 bvFTD and 76 AD patients and 152 healthy controls (HCs) from a Latin American consortium (ReDLat).Main results. The multimodal model yielded high area under the curve classification values (bvFTD patients vs HCs: 0.93 (±0.01); AD patients vs HCs: 0.95 (±0.01); bvFTD vs AD patients: 0.92 (±0.01)). The feature selection approach successfully filtered non-informative multimodal markers (from thousands to dozens).Results. Proved robust against multimodal heterogeneity, sociodemographic variability, and missing data.Significance. The model accurately identified dementia subtypes using measures readily available in underrepresented settings, with a similar performance than advanced biomarkers. This approach, if confirmed and replicated, may potentially complement clinical assessments in developing countriesPublication Multivariate word properties in fluency tasks reveal markers of Alzheimer's dementia(2024) Ferrante, Franco J.; Migeot, Joaquín; Birba, Agustina; Amoruso, Lucía; Pérez, Gonzalo; Hesse, Eugenia; Tagliazucchi, Enzo; Estienne, Claudio; Serrano, Cecilia; Slachevsky, Andrea; Matallana, Diana; Reyes, Pablo; Ibáñez, Agustín; Fittipaldi, Sol; Gonzalez, Cecilia; García, Adolfo M.Introduction: Verbal fluency tasks are common in Alzheimer's disease (AD) assessments. Yet, standard valid response counts fail to reveal disease-specific semantic memory patterns. Here, we leveraged automated word-property analysis to capture neurocognitive markers of AD vis-à-vis behavioral variant frontotemporal dementia (bvFTD). Methods: Patients and healthy controls completed two fluency tasks. We counted valid responses and computed each word's frequency, granularity, neighborhood, length, familiarity, and imageability. These features were used for group-level discrimination, patient-level identification, and correlations with executive and neural (magnetic resonanance imaging [MRI], functional MRI [fMRI], electroencephalography [EEG]) patterns. Results: Valid responses revealed deficits in both disorders. Conversely, frequency, granularity, and neighborhood yielded robust group- and subject-level discrimination only in AD, also predicting executive outcomes. Disease-specific cortical thickness patterns were predicted by frequency in both disorders. Default-mode and salience network hypoconnectivity, and EEG beta hypoconnectivity, were predicted by frequency and granularity only in AD. Discussion: Word-property analysis of fluency can boost AD characterization and diagnosis. Highlights: We report novel word-property analyses of verbal fluency in AD and bvFTD. Standard valid response counts captured deficits and brain patterns in both groups. Specific word properties (e.g., frequency, granularity) were altered only in AD. Such properties predicted cognitive and neural (MRI, fMRI, EEG) patterns in AD. Word-property analysis of fluency can boost AD characterization and diagnosis.