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Caracterização clínica, comportamental, sensorial e eletrofisiológica de crianças e adolescentes com dor reumatológica crônica: estudo transversal comparativo

2026-08-03T00:00:00Z

Título: Caracterização clínica, comportamental, sensorial e eletrofisiológica de crianças e adolescentes com dor reumatológica crônica: estudo transversal comparativo Autor(es): Silva, Tauane Grasiela dos Santos Abstract: Rheumatic conditions comprise a diverse group of diseases that predominantly affect the joints, but also muscles, bones, connective tissues, and internal organs, arising from immune-mediated, inflammatory, infectious, or degenerative mechanisms, characterized by a prolonged, painful, and function-limiting course, and which also affect children and adolescents. Among pediatric rheumatic conditions, juvenile idiopathic arthritis (JIA), of inflammatory and autoimmune nature, and juvenile fibromyalgia syndrome (JFS), of non-inflammatory nature and associated with central sensitization mechanisms, potentially involving cognitive, autonomic, and sensory dysfunction, stand out. In this context, electroencephalography (EEG) stands out as a tool for objectively characterizing the neurological processes underlying pediatric chronic pain. However, studies detailing the physiological mechanisms involved in JFS and JIA remain scarce. Objective: To characterize the clinical, behavioral, sensory, and electrophysiological profile of children and adolescents with chronic rheumatic pain resulting from juvenile fibromyalgia syndrome or juvenile idiopathic arthritis, compared with a healthy control group matched by sex and age range. Materials and Methods: This was an analytical, observational, cross-sectional study including children and adolescents of both sexes, aged 7 to 18 years, allocated into two groups: a pain group (JFS and JIA) and a control group. The groups were assessed using socioeconomic questionnaires, pain intensity (11-point numerical rating scale), mechanical detection threshold (esthesiometry), electrophysiological profile (electroencephalogram), and cognitive profile (auditory P300 event-related potential). Results: The sample consisted of 54 participants, 27 in the pain group and 27 in the control group, stratified into children and adolescents (24 children and 30 adolescents). A mean diagnostic delay of 21.3 months was observed in children and 50.7 months in adolescents. Children in the pain group showed generalized mechanical hypersensitivity to light touch at a site distant from the affected joint (p=0.004; d=−1.297), and adolescents in the pain group showed greater pain sensitivity to mechanical pressure (p=0.013 and p=0.045) and greater self-reported pain intensity (p=0.001) compared with controls. No intergroup EEG differences were identified under the resting-state condition. During the P300 paradigm, adolescents in the pain group showed greater relative amplitude in the theta band and lower relative amplitude in the beta3 band in the right anterior and posterior regions compared with controls (p<0.05; d ranging from 0.94 to 1.41), a finding significant under the uncorrected primary criterion adopted in this exploratory study; in a Benjamini-Hochberg sensitivity analysis restricted to relative-amplitude variables and applied per age subgroup within each experimental condition (m=24), right posterior theta power remained significant (q=0.015). In children, a differentiated pattern of right posterior relative amplitude was observed during exposure to educational and recreational screen conditions. The topographic pain contrast between diagnoses was statistically significant for back pain, leg pain, and headache, all more frequent in JFS (FDR-adjusted p<0.01). Conclusion: In response to the overall objective, the electrophysiological profile of children and adolescents with JFS and JIA, compared with healthy controls, was characterized by the absence of EEG differences at rest and by specific alterations under active cognitive and sensory demand. Children and adolescents with JFS and JIA present measurable sensory alterations and specific electrophysiological changes during conditions of active cognitive and sensory demand, though not generalized to the resting state, consistent with early stages of central sensitization and pain-related cognitive interference. These findings reinforce the relevance of early diagnosis as a possible therapeutic window and point to the need for longitudinal studies investigating the progression of these alterations throughout development.

Sensibilidade β-adrenérgica e variabilidade alterada da frequência cardíaca no hipotireoidismo: uma abordagem mecanicista

2026-08-21T00:00:00Z

Título: Sensibilidade β-adrenérgica e variabilidade alterada da frequência cardíaca no hipotireoidismo: uma abordagem mecanicista Autor(es): Rocha, Camila Souza Gama Abstract: Hypothyroidism is one of the most prevalent endocrine disorders worldwide, affecting more than 10% of adults, and is associated with structural and functional alterations of the cardiovascular system. Although its chronotropic and hemodynamic effects are well described, the mechanisms integrating autonomic modulation and β-adrenergic sensitivity in the genesis of cardiac electrical alterations are poorly understood. This study aimed to investigate changes in cardiac electrical function resulting from autonomic modulation associated with hypothyroidism in a murine model. Methods: Male Swiss mice were used (n = 6–7 per group; 5–6 weeks old; 25–30 g). Hypothyroidism was induced with methimazole (0.1% in drinking water) for 21 days, while the control group received water only. Cardiac function was assessed by in vivo electrocardiography on days 0, 11, and 21, determining heart rate, electrical conduction, and heart rate variability in the time and frequency domains. β-adrenergic sensitivity was analyzed through intraperitoneal administration of isoproterenol, dobutamine, and salbutamol, with electrocardiographic monitoring before and 3 minutes after administration. Adenylyl cyclase activity was assessed in isolated hearts perfused using a Langendorff system, before and after stimulation with forskolin. The expression of β₁ and β₂ receptors, protein kinase A (PKA), and phospholamban (PLB) was determined by Western blot. Results: Hypothyroid animals showed a significant reduction in heart rate, prolongation of the PR interval, and an increase in corrected QT. Heart rate variability revealed an increase in the Very Low Frequency (VLF) component, an increase in the Root mean square of successive differences (RMSSD), and a reduction in the Standard deviation of NN intervals (SDNN), characterizing autonomic imbalance with vagal predominance and decreased overall adaptability. Hypothyroid hearts showed a significant reduction in β₁-receptor expression and PKA substrate phosphorylation, as well as an increase in β₂-receptor expression. These results indicate that hypothyroidism reduces canonical β₁-adrenergic/PKA signaling while increasing β₂-adrenergic receptor expression. The chronotropic response to isoproterenol and dobutamine was attenuated, accompanied by reduced PKA substrate phosphorylation, indicating decreased cardiac β₁-adrenergic responsiveness. In contrast, the response to salbutamol was increased, with no changes in PKA substrate phosphorylation or PLB expression/phosphorylation, suggesting that β₁-adrenergic signaling is selectively impaired in hypothyroidism, with a possible reorganization toward the β₂-adrenergic signaling pathway. Forskolin stimulation restored the heart rate response without altering the p-PLB/PLB ratio, which remained unchanged, indicating preservation of the intracellular steps downstream of β-adrenergic receptor activation. Conclusion: Hypothyroidism induces marked remodeling of cardiac adrenergic signaling, with a greater contribution of alternative pathways associated with the β₂ adrenergic receptor. These findings demonstrate that thyroid hormone deficiency leads to reorganization of cardiac adrenergic signaling, contributing to bradycardia, reduced chronotropic adaptability, and decreased complexity of autonomic control in hypothyroidism.

Variação espaço-temporal de Donax gemmula (mollusca: donacidae) em praias arenosas de Aracaju, Sergipe, nordeste do Brasil

2026-07-29T00:00:00Z

Título: Variação espaço-temporal de Donax gemmula (mollusca: donacidae) em praias arenosas de Aracaju, Sergipe, nordeste do Brasil Autor(es): Silva, Caio Correia Régis da Abstract: Sandy beaches are highly dynamic environments that dominate continental coastlines. The genus Donax (Bivalvia: Tellinoidea: Donacidae) is one of the most common taxonomic groups on Brazilian beaches, distributed primarily in the intertidal and shallow infralittoral zones of tropical sandy shores. Donax gemmula is the smallest species of the genus in the southwestern Atlantic and was the dominant species on the beaches of Aracaju for several years. However, most ecological knowledge on this species comes from benthic macrofauna studies conducted in temperate and subtropical climates. The present study characterized the spatio-temporal variation in the abundance and maximum shell length (MSL) of D. gemmula in the swash zone of sandy beaches in Aracaju, Sergipe, northeastern Brazil, and assessed whether species abundance tracks the variation of oceanic, meteorological, and morphodynamic environmental variables in a tropical system. Eight sites along ~23 km of Aracaju's beaches were sampled bimonthly over one year (Sep/2024–Jul/2025). Specimens were identified, quantified, and measured through image thresholding. Environmental variables were measured in situ and retrieved from online databases. Spatio-temporal variation in abundance was analyzed using PERMANOVA, followed by PERMDISP and post-hoc analyses. The relationship between abundance and environmental variables was analyzed via LMMs, with date as a random factor. Environmental variables exhibited distinct temporal patterns. A total of 3,482 D. gemmula individuals were recorded. Mean abundance varied spatio-temporally, peaking in January and March, with the lowest values in May and July 2025. Spatial differences in mean abundance were detected only in January and May 2025. MSL ranged from 1.52 to 8.7 mm, with January and March showing the highest MSL values. Juveniles strongly dominated the population (96.5%). The LMM indicated a negative relationship between abundance and mean grain size. The observed abundance and size ranges fell within the values reported in the literature, contrasting with the macroecological pattern of reduction towards the tropics. Species abundance was higher in months characterized by higher temperatures, moderate flow discharge of the Sergipe River, lower oceanic chlorophyll-a (chla), and lower wave height; and was lower in months with higher accumulated rainfall. The negative association with chla contradicts the expected pattern of increased abundance with greater food availability. Overall, our findings suggest that patterns established for subtropical and temperate sandy beaches are not directly generalizable to tropical D. gemmula populations, highlighting the critical role of environmental context in driving the spatial and temporal variation of the species.

Personalidade colonial modula a toxicidade de inseticidas em cupins

2026-07-30T00:00:00Z

Título: Personalidade colonial modula a toxicidade de inseticidas em cupins Autor(es): Pedro, Ariele de Paiva São Abstract: Animal personality can influence importante ecological processes, including responses to environmental risks. Termites are social insects of great ecological importance in tropical exosystems due to their role in nutriente cycling and the economic damage caused by some species. Studies investigating colony personality in termites are scarce, and there is currently no evidence regarding the influence of colony personality on pest management efficiency. Here, we investigated whether differences in the activity levels of Nasutitermes corniger colonies are associated with susceptibility to the insecticide imidacloprid and with contaminant transmission among colony members. Initially, colony activity profiles were characterized using Principal Component Analysis (PCA). Based on the first principal component and complementary behavioral traits, six colonies were classified as exhibiting either low- or high-activity profiles. Toxicity and horizontal transfer bioassays were subsequently conducted and analyzed using mixed-effects models. We evaluated susceptibility to imidacloprid, as well as contaminant transfer and behavioral responses among members of low- and high-activity colonies. Our results showed that low-activity colonies were less susceptible to imidacloprid, requiring a 1.84-fold higher dose to achieve the same mortality observed in high-activity colonies. However, low-activity colonies exhibited higher mortality resulting from horizontal transfer than high-activity colonies. These findings may be explained by the fact that high-activity colonies displayed more vibrational behavior and a lower frequency of social interactions following exposure, which may have limited the horizontal transfer of the insecticide. In contrast, low-activity colonies exhibited greater aggregation and a higher frequency of interindividual contacts, facilitating the spread of the insecticide among colony members. This study demonstrates that colony personality can influence contaminant exposure, susceptibility, and transmission in termites, with potential implications for colony fitness as well as for the management of these insects.