Browsing by Author "Rothhammer, F."

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    Attention-deficit hyperactivity disorder involves differential cortical processing in a visual spatial attention paradigm
    (ELSEVIER IRELAND LTD, 2006) Lopez, V.; Lopez Calderon, J.; Ortega, R.; Kreither, J.; Carrasco, X.; Rothhammer, P.; Rothhammer, F.; Rosas, R.; Aboitiz, F.
    Objective: Inattention is undoubtedly one of the main characteristics of Attention-deficit hyperactivity disorder (ADHD). Nevertheless, a growing corpus of evidence shows that not all attentional processes are affected in this condition. This study aimed to explore the distribution of attentional resources in children with ADHD via a spatially shifted double-oddball visual task.
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    Déficit atencional con hiperactividad: trastorno multicausal de la conducta, con heredabilidad y comorbilidad genética moderadas
    (2017) Puddu, G.; Rothhammer, P.; Carrasco, X.; Aboitiz, Francisco; Rothhammer, F.
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    Intra-individual response variability assessed by ex-Gaussian analysis may be a new endophenotype for attention-deficit/hyperactivity disorder
    (2015) Henriquez-Henriquez, M. P.; Billeke, P.; Henriquez, H.; Zamorano, F. J.; Rothhammer, F.; Aboitiz, Francisco
    Intra-individual variability of response times (RTisv) is considered as potential endophenotype for attentional deficit/hyperactivity disorder (ADHD). Traditional methods for estimating RTisv lose information regarding response times (RTs) distribution along the task, with eventual effects on statistical power. Ex-Gaussian analysis captures the dynamic nature of RTisv, estimating normal and exponential components for RT distribution, with specific phenomenological correlates. Here, we applied ex-Gaussian analysis to explore whether intra-individual variability of RTs agrees with criteria proposed by Gottesman and Gould for endophenotypes. Specifically, we evaluated if normal and/or exponential components of RTs may (a) present the stair-like distribution expected for endophenotypes (ADHD > siblings > typically developing children (TD) without familiar history of ADHD) and (b) represent a phenotypic correlate for previously described genetic risk variants. This is a pilot study including 55 subjects (20 ADHD-discordant sibling-pairs and 15 TD children), all aged between 8 and 13 years. Participants resolved a visual Go/Nogo with 10% Nogo probability. Ex-Gaussian distributions were fitted to individual RT data and compared among the three samples. In order to test whether intra-individual variability may represent a correlate for previously described genetic risk variants, VNTRs at DRD4 and SLC6A3 were identified in all sibling-pairs following standard protocols. Groups were compared adjusting independent general linear models for the exponential and normal components from the ex-Gaussian analysis. Identified trends were confirmed by the non-parametric Jonckheere–Terpstra test. Stair-like distributions were observed for μ (p = 0.036) and σ (p = 0.009). An additional “DRD4-genotype” × “clinical status” interaction was present for τ (p = 0.014) reflecting a possible severity factor. Thus, normal and exponential RTisv components are suitable as ADHD endophenotypes.
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    Mendelian Randomization Analysis of the Relationship Between Native American Ancestry and Gallbladder Cancer Risk
    (2022) Zollner, L.; Boekstegers, F.; Ponce, C.B.; Scherer, D.; Marcelain, K.; Gárate-Calderón, V.; Waldenberger, M.; Morales, E.; Rojas, A.; Munoz, C.; Müller, B.; Retamales, J.; de Toro, G.; Kortmann, A.V.; Barajas, O.; Rivera, M.T.; Cortés, A.; Loader, D.; Saavedra, J.; Gutiérrez, L.; Ortega, A.; Bertrán, M.E.; Bartolotti, L.; Gabler, F.; Campos, M.; Alvarado, J.; Moisán, F.; Spencer, L.; Nervi Nattero, Bruno; Carvajal, D.; Losada, H.; Almau, M.; Fernández, P.; Olloquequi, J.; Carter, A.R.; Miquel, Juan Francisco; Bustos, B.I.; Guajardo, M.F.; Gonzalez-Jose, R.; Bortolini, M.C.; Acuña-Alonzo, V.; Gallo, C.; Linares, A.R.; Rothhammer, F.; Bermejo, J.L.
    Background A strong association between the proportion of Native American ancestry and the risk of gallbladder cancer (GBC) has been reported in observational studies. Chileans show the highest incidence of GBC worldwide, and the Mapuche are the largest Native American people in Chile. We set out to investigate the causal association between Native American Mapuche ancestry and GBC risk, and the possible mediating effects of gallstone disease and body mass index (BMI) on this association. Methods Markers of Mapuche ancestry were selected based on the informativeness for assignment measure and then used as instrumental variables in two-sample mendelian randomization (MR) analyses and complementary sensitivity analyses. Result We found evidence of a causal effect of Mapuche ancestry on GBC risk (inverse variance-weighted (IVW) risk increase of 0.8% for every 1% increase in Mapuche ancestry proportion, 95% CI 0.4% to 1.2%, p = 6.6×10-5). Mapuche ancestry was also causally linked to gallstone disease (IVW risk increase of 3.6% per 1% increase in Mapuche proportion, 95% CI 3.1% to 4.0%, p = 1.0×10-59), suggesting a mediating effect of gallstones in the relationship between Mapuche ancestry and GBC. In contrast, the proportion of Mapuche ancestry showed a negative causal effect on BMI (IVW estimate -0.006 kg/m2 per 1% increase in Mapuche proportion, 95% CI -0.009 to -0.003, p = 4.4×10-5). Conclusions The results presented here may have significant implications for GBC prevention and are important for future admixture mapping studies. Given that the association between Mapuche ancestry and GBC risk previously noted in observational studies appears to be causal, primary and secondary prevention strategies that take into account the individual proportion of Mapuche ancestry could be particularly efficient.
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    Specific Gram-Positive antibacterial activity of 4-(hydroxy-3-(3-methyl-2-butenyl) acetophenone isolated from senecio graveolens
    (2014) Santander T., Jaime A.; Otto, C.; Lowry, D.; Cuellar, M.; Mellado, M.; Salas Sánchez, Cristián Osvaldo; Rothhammer, F.; Echiburu-Chau, C.
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    The selective cytotoxicity elicited by phytochemical extract from Senecio graveolens ( Asteraceae) on breast cancer cells is enhanced by hypoxia
    (2014) Echiburu-Chau, C.; Alfaro Lira, S.; Brown, N.; Salas Sánchez, Cristián Osvaldo; Cuellar, M.; Santander T., Jaime A.; Ogalde, J.; Rothhammer, F.