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8,868 result(s) for "Martínez, Verónica"
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Type Three Secretion System in Attaching and Effacing Pathogens
Enteropathogenic and enterohemorrhagic are diarrheagenic bacterial human pathogens that cause severe gastroenteritis. These enteric pathotypes, together with the mouse pathogen , belong to the family of attaching and effacing pathogens that form a distinctive histological lesion in the intestinal epithelium. The virulence of these bacteria depends on a type III secretion system (T3SS), which mediates the translocation of effector proteins from the bacterial cytosol into the infected cells. The core architecture of the T3SS consists of a multi-ring basal body embedded in the bacterial membranes, a periplasmic inner rod, a transmembrane export apparatus in the inner membrane, and cytosolic components including an ATPase complex and the C-ring. In addition, two distinct hollow appendages are assembled on the extracellular face of the basal body creating a channel for protein secretion: an approximately 23 nm needle, and a filament that extends up to 600 nm. This filamentous structure allows these pathogens to get through the host cells mucus barrier. Upon contact with the target cell, a translocation pore is assembled in the host membrane through which the effector proteins are injected. Assembly of the T3SS is strictly regulated to ensure proper timing of substrate secretion. The different type III substrates coexist in the bacterial cytoplasm, and their hierarchical secretion is determined by specialized chaperones in coordination with two molecular switches and the so-called sorting platform. In this review, we present recent advances in the understanding of the T3SS in attaching and effacing pathogens.
Gaze Following as an Early Diagnostic Marker of Autism in a New Word Learning Task in Toddlers
The aim was to test the use of eye-tracking methodology for the early detection of ASD in a task of association between unfamiliar objects and pseudowords. Significant differences were found between ASD (n = 57) and TD (n = 57) Spanish speaking toddlers in the number and time of fixation. The TD children showed more and longer fixations on eyes and mouth while the ASD children attended almost exclusively to objects, making it difficult to integrate lexical and phonological information. Moreover, the TD toddlers looked at the mouth when the pseudoword was produced while the ASD toddlers did not. Gaze fixation on eyes and mouth during word learning recorded by eye-tracking may be used as a biomarker for the early diagnosis of ASD.
The valproic acid rat model of autism presents with gut bacterial dysbiosis similar to that in human autism
Background Gut microbiota has the capacity to impact the regular function of the brain, which can in turn affect the composition of microbiota. Autism spectrum disorder (ASD) patients suffer from gastrointestinal problems and experience changes in gut microbiota; however, it is not yet clear whether the change in the microbiota associated with ASD is a cause or a consequence of the disease. Methods We have investigated the species richness and microbial composition in a valproic acid (VPA)-induced rat model autism. Fecal samples from the rectum were collected at necropsy, microbial total DNA was extracted, 16 rRNA genes sequenced using Illumina, and the global microbial co-occurrence network was constructed using a random matrix theory-based pipeline. Collected rat microbiome data were compared to available data derived from cases of autism. Results We found that VPA administration during pregnancy reduced fecal microbial richness, changed the gut microbial composition, and altered the metabolite potential of the fecal microbial community in a pattern similar to that seen in patients with ASD. However, the global network property and network composition as well as microbial co-occurrence patterns were largely preserved in the offspring of rats exposed to prenatal administration of VPA. Conclusions Our data on the microbiota of the VPA rat model of autism indicate that this model, in addition to behaviorally and anatomically mimicking the autistic brain as previously shown, also mimics the microbiome features of autism, making it one of the best-suited rodent models for the study of autism and ASD.
Suppression of age-related salivary gland autoimmunity by glycosylation-dependent galectin-1-driven immune inhibitory circuits
Aging elicits quantitative and qualitative changes in different immune components, leading to disruption of tolerogenic circuits and development of autoimmune disorders. Galectin-1 (Gal1), an endogenous glycan-binding protein, has emerged as a regulator of immune cell homeostasis by shaping the fate of myeloid and lymphoid cells. Here, we demonstrate that aged Gal1-null mutant (Lgals1−/−) mice develop a spontaneous inflammatory process in salivary glands that resembles Sjögren’s syndrome. This spontaneous autoimmune phenotype was recapitulated in mice lacking β1,6N-acetylglucosaminyltransferase V (Mgat5), an enzyme responsible for generating β1,6-branched complex N-glycans, which serve as a major ligand for this lectin. Lack of Gal1 resulted in CD11c⁺ dendritic cells (DCs) with higher immunogenic potential, lower frequency of Foxp3⁺ regulatory T cells (Tregs), and increased number of CD8⁺ T cells with greater effector capacity. Supporting its tolerogenic activity, Gal1 expression decreased with age in autoimmunity-prone nonobese diabetic (NOD) mice. Treatment with recombinant Gal1 restored tolerogenic mechanisms and reduced salivary gland inflammation. Accordingly, labial biopsies from primary Sjögren’s syndrome patients showed reduced Gal1 expression concomitant with higher number of infiltrating CD8⁺ T cells. Thus, endogenous Gal1 serves as a homeostatic rheostat that safeguards immune tolerance and prevents age-dependent development of spontaneous autoimmunity.
Deciphering tissue-induced Klebsiella pneumoniae lipid A structure
This work was also supported by a Spanish Ministry of Economy and Competitiveness Grant (Biomedicine Programme, SAF2012-39841), Marie Curie Career Integration Grant U-KARE (PCIG13-GA-2013-618162), and Queen’s University Belfast start-up funds (to J.A.B.).
Role of extracellular vesicles in the pathogenesis of mosquito-borne flaviviruses that impact public health
Mosquito-borne flaviviruses represent a public health challenge due to the high-rate endemic infections, severe clinical outcomes, and the potential risk of emerging global outbreaks. Flavivirus disease pathogenesis converges on cellular factors from vectors and hosts, and their interactions are still unclear. Exosomes and microparticles are extracellular vesicles released from cells that mediate the intercellular communication necessary for maintaining homeostasis; however, they have been shown to be involved in disease establishment and progression. This review focuses on the roles of extracellular vesicles in the pathogenesis of mosquito-borne flavivirus diseases: how they contribute to viral cycle completion, cell-to-cell transmission, and cellular responses such as inflammation, immune suppression, and evasion, as well as their potential use as biomarkers or therapeutics (antiviral or vaccines). We highlight the current findings concerning the functionality of extracellular vesicles in different models of dengue virus, Zika virus, yellow fever virus, Japanese encephalitis virus, and West Nile virus infections and diseases. The available evidence suggests that extracellular vesicles mediate diverse functions between hosts, constituting novel effectors for understanding the pathogenic mechanisms of flaviviral diseases.
The topology of genome-scale metabolic reconstructions unravels independent modules and high network flexibility
The topology of metabolic networks is recognisably modular with modules weakly connected apart from sharing a pool of currency metabolites. Here, we defined modules as sets of reversible reactions isolated from the rest of metabolism by irreversible reactions except for the exchange of currency metabolites. Our approach identifies topologically independent modules under specific conditions associated with different metabolic functions. As case studies, the E . coli i JO1366 and Human Recon 2.2 genome-scale metabolic models were split in 103 and 321 modules respectively, displaying significant correlation patterns in expression data. Finally, we addressed a fundamental question about the metabolic flexibility conferred by reversible reactions: “Of all Directed Topologies (DTs) defined by fixing directions to all reversible reactions, how many are capable of carrying flux through all reactions?”. Enumeration of the DTs for i JO1366 model was performed using an efficient depth-first search algorithm, rejecting infeasible DTs based on mass-imbalanced and loopy flux patterns. We found the direction of 79% of reversible reactions must be defined before all directions in the network can be fixed, granting a high degree of flexibility.
Preliminary feasibility and clinical utility of the Unified Protocol for the transdiagnostic treatment of emotional disorders in people with long COVID-19 condition: A single case pilot study
The implementation of psychological interventions in long COVID-19 patients is still very limited. This study aims to analyze the feasibility and preliminary utility of the Unified Protocol (UP), for the psychological treatment of emotional disorders in long COVID-19 patients. 12 long COVID-19 patients (mean age = 47.92; SD = 13.18) presenting emotional disorders/symptoms received the UP through 8 online sessions. All participants completed the UP psychological program, attending all eight sessions and the 6-month follow-up appointment. However, adherence to the assessment protocol was lower, with a 33% dropout rate at the 6-month follow-up. High satisfaction was reported with both the UP program (mean = 9.75) and the online format. Satisfaction with individual UP modules ranged from 7.17 to 9 points (from 0 = any satisfaction to 10 = highest satisfaction). Qualitative feedback emphasized the usefulness of the UP program, with some participants suggesting additional contents (i.e., training in assertive communication skills), more personalized modules (i.e., providing just some UP modules) or increasing the number of sessions. In terms of the UP clinical utility, 25 mental clinical diagnoses were established at pre-assessment; 50% of participants no longer met criteria for a mental clinical diagnosis at post-assessment, increasing to 67% at follow-up. Most therapeutic objectives were achieved or initiated over the course of the intervention (78% at post-assessment; 86% at follow-up). At post-assessment significant improvements were observed in anxiety (8 participants), depression (9 participants), emotion dysregulation (4 participants) and quality of life scores (7 participants), although 2 participants did not maintain these gains in emotion regulation and quality of life at follow-up. The promising results of the UP in terms of high participant satisfaction and clinical improvements in anxiety and depression scores suggest that the UP could be a valuable psychological intervention for individuals with long COVID-19 and comorbid emotional disorders. The modest improvements found in other outcomes highlighted the need to better adapt the psychological interventions for long COVID-19 patients.
La Niña Obscures the North Atlantic Response to Sudden Stratospheric Warmings in C3S Seasonal Forecasts
Sudden stratospheric warmings (SSWs) can alter the North Atlantic circulation on subseasonal‐to‐seasonal timescales, typically leading to an equatorward shift of the eddy‐driven jet. However, this response is highly variable and can be modulated by other sources of climate variability. Using seasonal forecasts, this study investigates the modulation of the North Atlantic response to SSWs by El Niño–Southern Oscillation (ENSO). Forecast systems reproduce the tropospheric variability following SSWs found in reanalysis, including an increase of events followed by a poleward‐positioned jet during La Niña winters. Composite analysis reveals that SSWs increase the likelihood of an equatorward‐shifted jet and negative North Atlantic Oscillation compared to non‐SSW members during both ENSO phases, but La Niña masks this response due to their opposing influence on the North Atlantic mean state. This study highlights the importance of accounting for ENSO when predicting SSW impacts on the circulation and surface extremes on subseasonal timescales.
Risk factors for COVID-19 mortality: The effect of convalescent plasma administration
Convalescent plasma, widely utilized in viral infections that induce neutralizing antibodies, has been proposed for COVID-19, and preliminary evidence shows that it might have beneficial effect. Our objective was to determine the risk factors for 28-days mortality in patients who received convalescent plasma for COVID-19 compared to those who did not, who were admitted to hospitals in Buenos Aires Province, Argentina, throughout the pandemic. This is a multicenter, retrospective cohort study of 2-month duration beginning on June 1, 2020, including unselected, consecutive adult patients with diagnosed COVID-19, admitted to 215 hospitals with pneumonia. Epidemiological and clinical variables were registered in the Provincial Hospital Bed Management System. Convalescent plasma was supplied as part of a centralized, expanded access program. We analyzed 3,529 patients with pneumonia, predominantly male, aged 62±17, with arterial hypertension and diabetes as main comorbidities; 51.4% were admitted to the ward, 27.1% to the Intensive Care Unit (ICU), and 21.7% to the ICU with mechanical ventilation requirement (ICU-MV). 28-day mortality was 34.9%; and was 26.3%, 30.1% and 61.4% for ward, ICU and ICU-MV patients. Convalescent plasma was administered to 868 patients (24.6%); their 28-day mortality was significantly lower (25.5% vs. 38.0%, p<0.001). No major adverse effects occurred. Logistic regression analysis identified age, ICU admission with and without MV requirement, diabetes, and preexistent cardiovascular disease as independent predictors of 28-day mortality, whereas convalescent plasma administration acted as a protective factor. Our study suggests that the administration of convalescent plasma in COVID-19 pneumonia admitted to the hospital might be associated with improved outcomes.