Artículos de conferencia

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HIV infection of astrocytes increases release of Dickkopf-1 protein by a gap junction and hemichannel dependent mechanism
(Springer, 2012) Orellana Roca, Juan Andrés; Sáez, Juan Carlos; Berman, Joan; Eugenín Arce, Eliseo Alberto
Human immunodeficiency virus-1 (HIV) is a major public health issue, with a significant CNS complication of infection, NeuroAIDS. In vivo, microglia/macrophages are the main cells infected. However, a low but significant number of HIV infected astrocytes also has been detected, but their role in the pathogenesis of NeuroAIDS is not well understood. Our previous data indicated that HIV infection of astrocytes increased expression of the glycoprotein, dickkopf-1 protein (Dkk1), a soluble inhibitor of the wnt pathway. In HIV infected cultures of human astrocytes, secretion of Dkk1 was highly regulated by functional gap junction channels and connexin43 hemichannels. We also demonstrated that Dkk1 expression in astrocytes was increased in human brain tissue sections of individuals with HIV encephalitis as compared to tissue sections from uninfected individuals. We demonstrated that in primary cells, Dkk1 secretion did not participate in bystander killing of uninfected astrocytes or viral reactivation. However, its secretion regulates neuronal damage measured by collapse of neuronal processes. Thus, we demonstrated that HIV infection of astrocytes dysregulates secretion of Dkk1 by a mechanisms that involves both gap junctions as well as hemichannels that contributes to the neuropathogenesis observed in HIV infected individuals.
Impact of Awake Prone Positioning on Inspiratory Effort and Work of Breathing. A Physiological Study in Healthy Subjects
(American Thoracic Society, 2022) Damiani Rebolledo, L. Felipe; Basoalto Escobar, Roque Ignacio; Bachmann Barrón, María Consuelo; Jalil Contreras, Yorschua Frederick; Acuña, V.; Díaz, G.; Mella, J.; García Valdés, Patricio Hernán; Moya Gallardo, Eduardo Sebastián; Villarroel, G.; Retamal Montes, Jaime; Bugedo Tarraza, Guillermo; Bruhn, Alejandro
Is Gamma (P.1) Variant Associated with a Higher Severity in ICU Patients with SARS-CoV-2 Infection
(2022) Vera, M.; Angulo, J.; Medina, R.; Ferres, M.; Bruhn, A.; Castro, R.; Pardo-Roa, C.
The Omicron variant of SARS-CoV-2 has been shown to evade neutralizing antibodies elicited by vaccination or infection. Despite the global spread of the Omicron variant, even among highly vaccinated populations, death rates have not increased concomitantly. These data suggest that immune mechanisms beyond antibody-mediated virus neutralization may protect against severe disease. In addition to neutralizing pathogens, antibodies contribute to control and clearance of infections through Fc effector mechanisms. Here, we probed the ability of vaccine-induced antibodies to drive Fc effector activity against the Omicron variant using samples from individuals receiving one of three SARS-CoV-2 vaccines. Despite a substantial loss of IgM, IgA, and IgG binding to the Omicron variant receptor binding domain (RBD) in samples from individuals receiving BNT162b2, mRNA-1273, and CoronaVac vaccines, stable binding was maintained against the full-length Omicron Spike protein. Compromised RBD binding IgG was accompanied by a loss of RBD-specific antibody Fc gamma receptor (Fe gamma R) binding in samples from individuals who received the CoronaVac vaccine, but RBD-specific Fc gamma R2a and Fc gamma R3a binding was preserved in recipients of mRNA vaccines. Conversely, Spike protein-specific antibodies exhibited persistent but reduced binding to Fc gamma Rs across all three vaccines, although higher binding was observed in samples from recipients of mRNA vaccines. This was associated with preservation of Fc gamma R2a and Fc gamma R3a binding antibodies and maintenance of Spike protein-specific antibody-dependent natural killer cell activation. Thus, despite the loss of Omicron neutralization, vaccine-induced Spike protein-specific antibodies continue to drive Fc effector functions, suggesting a capacity for extraneutralizing antibodies to contribute to disease control.
On the Accuracy of Eikonal Approximations in Cardiac Electrophysiology in the Presence of Fibrosis
(Springer, 2023) Gander, Lia; Krause, Rolf; Weiser, Martin; Sahli Costabal, Francisco; Pezzuto, Simone
Fibrotic tissue is one of the main risk factors for cardiac arrhythmias. It is therefore a key component in computational studies. In this work, we compare the monodomain equation to two eikonal models for cardiac electrophysiology in the presence of fibrosis. We show that discontinuities in the conductivity field, due to the presence of fibrosis, introduce a delay in the activation times. The monodomain equation and eikonal-diffusion model correctly capture these delays, contrarily to the classical eikonal equation. Importantly, a coarse space discretization of the monodomain equation amplifies these delays, even after accounting for numerical error in conduction velocity. The numerical discretization may also introduce artificial conduction blocks and hence increase propagation complexity. Therefore, some care is required when comparing eikonal models to the discretized monodomain equation.
Polygastric flexor muscle of the index finger and its clinical implications
(2023) Riveros, Andrés; Inzunza, Óscar; Burdiles, Álvaro; Farfán, Emilio
Although muscle variations in the forearm have been widely reported, the presence of supernumerary muscles in this compartment may be associated with compressive disorders of the nerves of the upper limb. The purpose of this study was to report the finding of a polygastric flexor muscle of the index finger (PFID), a supernumerary muscle associated with the anterior compartment of the forearm, the morphology and pathway of which are closely related to the median nerve. The PFID was found in a routine dissection of an upper right limb. Following a dissection methodology by planes, a narrow, polygastric muscle was identified, formed sequentially and interspersed by four tendons and three muscle bellies, that extended between the common flexor muscle mass of the anterior compartment of the forearm and the index finger. The sixth part of the PFID was partially in the carpal tunnel and established close relation with the median nerve, which was displaced superficially. Knowledge of this and other muscle variations that appear in the forearm and carpal tunnel are relevant when performing a differential diagnosis of carpal tunnel syndrome or in planning surgery on this canal.
Proposed Model to Understand Coping Mechanisms Development in Athletes Living with Type 1 Diabetes to Address Physical Activity Barriers
(Mary Ann Liebert, Inc., publishers, 2024) Montt Blanchard, Denise
Background and Aims: Individuals with Type 1 diabetes (T1D) often face distinct hurdles in high‐performance sports, with some athletes using coping mechanisms that remain poorly understood. This study explores the significance of these coping mechanisms in overcoming T1D‐related barriers in competitive physical activities among young and adult patients in Chile. By delving into these mechanisms, the study aims to bridge knowledge gaps in T1D management within high‐performance sports, ultimately promoting physical activity for individuals with T1D. Methods: An interdisciplinary patient‐centered approach was employed in this study. In‐depth interviews were conducted with thirty competitive athletes with T1D who participated in any Olympic sport at a competitive level. The interviews were transcribed verbatim and analyzed using QcaMap. Thematic analysis was carried out by professionals from behavioral sciences and design to comprehensively examine the coping mechanisms of the participants. Results: The study reveals three key insights for T1D self‐management in high‐performance sports: negative influences driving competitive training motivation, physical coping mechanisms for diabetes, and positive outcomes impacting performance. Examined through psychological behavior theory, these insights deepen our understanding of T1D management in sports. Conclusions: This research provides insights into how athletes with T1D overcome physical activity barriers, offering a model for understanding strategies. These insights can guide inclusive design solutions to promote physical activity in T1D, linking behavioral science and design. This interdisciplinary approach contributes to health psychology and design management, potentially enhancing lives and athletic performance of individuals with T1D while inspiring innovations in diabetes care and physical activity promotion.
Psychosocial stress affects attentional control and neural oscillatory activity
(2015) Palacios García, Ismael; Villena González, Mario; Campos Arteaga, German; Artigas Vergara, Claudio; Jaramillo, Karina; Silva, Jaime; Rodríguez, Eugenio
Every day we have to divide our limited attentional resources into different external and internal demands. Considering that psychosocial stress promotes the allocation of attentional resources to threat-related stimuli such as the social evaluation, the aim of the study is (1) to investigate if psychosocial stress affects the behavioral performance in an attentional shifting task and (2) to search, under an exploratory approach, some of its neural correlates. 40 healthy participants were exposed to either an electroencephalogram-compatible version of the Trier Social Stress Test (TSST) or a control protocol. Additionally, immediately before and after these protocols, subject participated in the attentional shifting task. Manipulation checks were verified through the changes of the heart rate, salivary concentration of cortisol and the score in the anxiety scale in the “stress” condition respect the control. When we compared the behavioral performance in the attentional task prior and after both conditions, we found that the control group showed a clear improvement in performance, characterized by a relative increase of correct trials and a decrease of omissions. Analogously, after the TSST, participants showed a decreases of the correct trials and an increase of omissions. In addition to behavioral results, we found that the oscillatory activity in alpha (8–12 Hz) and gamma bands (30–70 Hz) were different in both conditions. Behavioral and electrophysiological results, suggest that psychosocial stress directs the attention internally, limiting the attentional resources for attending the external demands and inducing cognitive failures.
Relationship of Multifocal Electroretinographic Responses and Macular Layer Volume in Eyes Treated for Retinopathy of Prematurity
(ASSOC RESEARCH VISION OPHTHALMOLOGY INC, 2022) AlWattar, Bilal K.; Patel, Jagvi K.; Fonseca, Mariana I.; Nouck-A-Nwal, Alexandra; Altschwager, Pablo; Fulton, Anne B.; Akula, James D.
Purpose: To determine the association of the multifocal electroretinographic (mfERG) response amplitude with the volumes of the inner, postreceptor, and photoreceptor retinal layers in the region stimulated by each mfERG element.Methods: Sixteen healthy, young adult control subjects were studied. Each of the 103 hexagonal elements of the standard, scaled mfERG were aligned, where possible, with patches of retina imaged using optical coherence tomography. Stimuli falling on the fovea and on the optic nerve head were excluded. Linear mixed-effects modeling was then used to derive estimated coefficients (voltage/volume) for the mfERG response throughout the full 80 ms standard epoch. The resulting predicted response amplitudes originating in each layer were then compared to pharmacologically "dissected" mfERGs obtained from other studies in monkey eyes.Results: Across the duration of the response, the amplitude of the modeled contribution from (1) the inner retina was small-to-modest, (2) the postreceptor retina was larger and contained two prominent peaks, and (3) the photoreceptor response was the largest and most closely paralleled the overall (i.e., intact) response, including late-appearing oscillations. The significance of each layer's contribution was greatest when the absolute amplitude of that layer's response was largest. The contribution of the inner retina was maximally significant in the interval between the prominent troughs and peaks of the intact response. The contributions of the postreceptor and photoreceptor responses were maximally significant at the prominent troughs and peaks of the intact response.Conclusions: The results of the model were in good overall agreement with previous interpretations of the cellular contributions to the mfERG. There was also fair agreement with pharmacologically dissected monkey mfERG responses. Thus, the estimations of the contributions of the retinal layers to the mfERG so produced appeared plausible.
SDF-1/CXCL12 induces migration of lymphocytes by a mechanism pannexin1 hemichannel dependent
(AMER SOC CELL BIOLOGY, 2012) Velásquez, Stephani; Orellana Roca, Juan Andrés; Sáez, Juan Carlos; Eugenín Arce, Eliseo Alberto
Teledermatology and Artificial Intelligence
(2022) Navarrete Dechent, Cristián Patricio
Background: The use of artificial intelligence (AI) algorithms for the diagnosis of skin diseases has shown promise in experimental settings but has not yet been tested in real-life conditions. The COVID-19 pandemic led to a worldwide disruption of health systems, increasing the use of telemedicine. There is an opportunity to include AI algorithms in the teledermatology workflow. Objective: The aim of this study is to test the performance of and physicians’ preferences regarding an AI algorithm during the evaluation of patients via teledermatology. Methods: We performed a prospective study in 340 cases from 281 patients using patient-taken photos during teledermatology encounters. The photos were evaluated by an AI algorithm and the diagnosis was compared with the clinician’s diagnosis. Physicians also reported whether the AI algorithm was useful or not. Results: The balanced (in-distribution) top-1 accuracy of the algorithm (47.6%) was comparable to the dermatologists (49.7%) and residents (47.7%) but superior to the general practitioners (39.7%; P=.049). Exposure to the AI algorithm results was considered useful in 11.8% of visits (n=40) and the teledermatologist correctly modified the real-time diagnosis in 0.6% (n=2) of cases. Algorithm performance was associated with patient skin type and image quality. Conclusions: AI algorithms appear to be a promising tool in the triage and evaluation of lesions in patient-taken photographs via telemedicine.
Tenorio syndrome: description of 9 new cases and review of the clinical and molecular features
(2022) Guillermo Lay-Son
Tenorio syndrome (TNORS) (OMIM #616260) is a relatively recent disorder with very few cases described so far. Clinical features included macrocephaly, intellectual disability, hypotonia, enlarged ventricles and autoimmune diseases. Molecular underlying mechanism demonstrated missense variants and a large deletion encompassing RNF125, a gene that encodes for an U3 ubiquitin ligase protein. Since the initial description of the disorder in six patients from four families, several new patients were diagnosed, adding more evidence to the clinical spectrum. In this article, we described 14 additional cases with deep phenotyping and make an overall review of all the cases with pathogenic variants in RNF125. Not all patients presented with overgrowth, but instead, most patients showed a common pattern of neurodevelopmental disease, macrocephaly and/or large forehead. Segregation analysis showed that, though the variant was inherited in some patients from an apparently asymptomatic parent, deep phenotyping suggested a mild form of the disease in some of them. The mechanism underlying the development of this disease is not well understood yet and the report of further cases will help to a better understanding and clinical characterization of the syndrome.
The Fibrotic Kernel Signature: Simulation-Free Prediction of Atrial Fibrillation
(2023) Sahli Costabal, Francisco; Banduc, Tomás; Gander, Lia; Pezzuto, Simone
We propose a fast classifier that is able to predict atrial fibrillation inducibility in patient-specific cardiac models. Our classifier is general and it does not require re-training for new anatomies, fibrosis patterns, and ablation lines. This is achieved by training the classifier on a variant of the Heat Kernel Signature (HKS). Here, we introduce the “fibrotic kernel signature” (FKS), which extends the HKS by incorporating fibrosis information. The FKS is fast to compute, when compared to standard cardiac models like the monodomain equation. We tested the classifier on 9 combinations of ablation lines and fibrosis patterns. We achieved maximum balanced accuracies with the classifiers ranging from 75.8% to 95.8%, when tested on single points. The classifier is also able to predict very well the overall inducibility of the model. We think that our classifier can speed up the calculation of inducibility maps in a way that is crucial to create better personalized ablation treatments within the time constraints of the clinical setting.

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