Frontiers in Physiology最新文献

Pulmonary embolism (PE) is a common and potentially fatal obstructive disease of the pulmonary arteries; early diagnosis and continuous monitoring are particularly critical in critically ill patients. Electrical impedance tomography (EIT), a noninvasive and radiation-free imaging modality that enables real-time bedside monitoring, offers a promising approach for adjunctive diagnosis and perfusion assessment of PE, especially in patients who cannot undergo computed tomography pulmonary angiography (CTPA) due to instability or other contraindications. Building upon an overview of EIT imaging principles and recent advances in pulmonary perfusion monitoring, this review concentrates on the bedside application of EIT and the clinical value of EIT in bedside assessment of PE. Unlike prior research, this study proposes an EIT perfusion imaging strategy using a hypertonic saline bolus for the diagnosis of PE and compares it with bedside monitoring based on cardiac impedance signals. Additionally, we assess the current clinical evidence according to GRADE standards and identify its existing limitations. Finally, we further discuss the key challenges hindering clinical translation of EIT and outline future directions. This review aims to provide clinicians and researchers with a reference to facilitate broader adoption of EIT in the bedside monitoring of PE.

Introduction: Bipolar disorder (BD) is a severe psychiatric disorder characterized by shifting of mood patterns from manic to depressive episodes. The molecular mechanisms underlying BD have not been fully elucidated, and research into biomarkers is important for prevention and early intervention. The Na⁺, K⁺-ATPase is a metalloprotein that interacts with many chemical elements. It was demonstrated that the interactions of Na⁺, K⁺-ATPase with endogenous cardiac steroids is involved in BD. It was hypothesized that these interactions are mimicked by chemical elements which may participate in BD etiology. We have recently demonstrated that the concentration of Aluminum (Al), Boron (B), Cupper (Cu), Potassium (K), Magnesium (Mg) and Vanadium (V) were significantly lower in the pre-frontal cortex of individuals with BD compared with controls. We hypothesized that differences in the levels of chemical elements between BD and healthy controls would also be reflected in scalp hair.

Methods: To test this hypothesis, the levels of 25 chemical elements were determined by Inductively coupled plasma mass spectrometry (ICP-MS) in the scalp hair of 30 individuals with BD and 30 sex- and age-matched controls.

Results: We found that the levels of Al, Cu, Nickel (Ni) and Thallium (Tl) are elevated in the hair of BD patients compared to controls. In addition, the concentrations of Ni levels in hair samples were correlated with the severity of the mental illness as quantified by the Global Assessment of Functioning Scale.

Conclusion: Although interpretations are tentative due to the limited sample size, our results suggest that changes in chemical elements may be involved either in the etiology of BD or altered due to the disease progression, which needs to be clarified further in larger independent samples.

Scanpath analysis provides a powerful window into visual behavior by jointly capturing the spatial organization and temporal dynamics of gaze. By linking perception, cognition, and oculomotor control, scanpaths offer rich insights into how individuals explore visual scenes and accomplish task goals. Despite decades of research, however, the field remains methodologically fragmented, with a wide diversity of representations and comparison metrics that complicate interpretation and methodological choice. This article reviews computational approaches for the characterization and comparison of scanpaths, with an explicit focus on their underlying assumptions, interpretability, and practical implications. We first survey representations and metrics designed to describe individual scanpaths, ranging from geometric descriptors and spatial density representations to more advanced approaches such as attention maps, recurrence quantification analysis, and symbolic string encodings that capture temporal regularities and structural patterns. We then review methods for comparing scanpaths across observers, stimuli, or tasks, including point-mapping metrics, elastic alignment techniques, string-edit distances, saliency-based measures, and hybrid approaches integrating spatial and temporal information. Across these methods, we highlight their respective strengths, limitations, and sensitivities to design choices such as discretization, spatial resolution, and temporal weighting. Rather than promoting a single optimal metric, this review emphasizes scanpath analysis as a family of complementary tools whose relevance depends on the research question and experimental context. Overall, this work aims to provide a unified conceptual framework to guide methodological selection, foster reproducibility, and support the meaningful interpretation of gaze dynamics across disciplines.

Background: Plyometric training may enhance upper-limb explosive performance and stroke velocity in youth badminton players while contributing to mitigate injury risk, yet the influence of biological maturation on these adaptations remains unclear.

Purpose: To compare the effects of upper-limb plyometric training (PLYOgen), technical plyometric training integrating badminton stroke mechanics (PLYObad), and regular training on upper-limb strength, plyometric performance, and smash speed while accounting for maturity offset.

Methods: Sixty-two male players (12-14 years) were randomized to PLYOgen, PLYObad, or control. All groups continued their usual badminton practice (2-3 sessions/week; 75-90 min/session). Over 6 weeks, only the intervention groups completed an additional supervised plyometric session once per week (25-30 min; 72 explosive actions), whereas the control group performed no additional plyometric/strength sessions. Repeated-measures ANCOVA with maturity offset as covariate assessed pre-post changes in overhead medicine ball throw, seated chest pass, plyometric push-up height, and smash speed.

Results: Significant time effects were observed for all outcomes (p < 0.001; η²p = 0.737-0.954). Time × maturity-offset interactions were significant for overhead throw (p < 0.001; η²p = 0.571), chest pass (p < 0.001; η²p = 0.482), push-up height (p = 0.006; η²p = 0.122), and smash speed (p < 0.001; η²p = 0.360), indicating that players with higher maturity offset (closer to or beyond PHV) tended to show larger pre-post improvements. Time × group interactions were also significant for overhead throw (p < 0.001; η²p = 0.918), chest pass (p < 0.001; η²p = 0.840), push-up height (p < 0.001; η²p = 0.718), and smash speed (p < 0.001; η²p = 0.950). Post-hoc analysis showed PLYOgen and PLYObad improved overhead throw and smash speed more than control, with PLYOgen also presenting greater values than control in push-up height.

Conclusion: Both plyometric approaches enhanced upper-limb explosive performance, with biological maturation significantly moderating training responsiveness. This should be considered when modifying youth training programs to manage injury risk factors and to ensure that training practices are appropriately aligned with the players' developmental level.

Accurate prediction of asymptomatic small abdominal aortic aneurysm (AAA) growth is crucial for risk stratification and personalized surveillance. This study developed an end-to-end deep learning framework to predict rapid expansion (≥0.5 cm/6 months) using computed tomography angiography (CTA) images from 81 asymptomatic patients with small AAA (30 rapid-growth and 51 stable patients). The pipeline integrated three core components: a ResNet50 classifier for identifying aortic images (99.86% accuracy, 99.91% F1-score), a YOLOv11 detector for localizing aneurysms (precision-recall: 0.902), and a MedMamba-based feature fusion model that combined imaging features with clinical metadata via multi-head self-attention. Model robustness was ensured through stratified 5-fold cross-validation and comprehensive data augmentation. The fusion model achieved a predictive accuracy of 98.75% and an F1-score of 97.78, outperforming seven classical deep learning backbones. Furthermore, explainability analyses confirmed the model's reliance on established clinical risk factors and highlighted biologically plausible imaging regions for prediction. The proposed ResNet50-YOLOv11-MedMamba framework demonstrates the feasibility of automating AAA growth prediction directly from CTA and shows promising potential to enhance clinical decision-making.

Objectives: This study aimed to investigate the effects of velocity-based training (VBT) on lower-limb explosive performance in adolescent sprinters and to compare the training adaptations induced by different velocity loss thresholds (VLT).

Methods: Forty-five male adolescent sprinters were randomly assigned to three experimental groups that trained with VLT of 10% (G1), 20% (G2), and 30% (G3), respectively. All participants completed a 6-week VBT squat program performed twice per week at an intensity of 80% 1RM, with a fixed total volume of 20 repetitions per session. The session rating of perceived exertion (sRPE) was used to monitor subjective fatigue. Pre- and post-intervention tests included 30 m sprint performance, squat 1RM, countermovement jump (CMJ) height and relative peak power, and drop jump (DJ) reactive strength index (RSI). Data were analyzed using one-way ANOVA and paired-sample t-tests.

Results: After 6 weeks of training, all groups showed significant improvements in squat 1RM, 30 m sprint performance, CMJ height, CMJ relative peak power, and DJ RSI (p < 0.05). Between-group comparisons revealed no significant differences in 1RM improvement (p > 0.05), whereas the 10% VLT group demonstrated significantly greater enhancements in CMJ height, CMJ relative peak power, 30 m sprint performance, and RSI compared with the 30% VLT group (p < 0.05). The overall trend in performance gains was consistent: 10% VLT > 20% VLT> 30% VLT. Monitoring data showed that sRPE values increased significantly with higher VLT (p < 0.001), indicating that lower VLT settings effectively reduced fatigue accumulation.

Conclusion: VBT is an effective method for improving lower-limb explosive performance in adolescent sprinters. Under fixed training volume conditions, applying a lower VLT (e.g.,10%) produces superior training outcomes, likely due to reduced fatigue, maintenance of higher movement velocity and power output, and enhanced neuromuscular adaptations. Coaches are therefore advised to prioritize lower VLT when designing VBT programs aimed at developing explosive strength in youth sprinters.

Introduction: Met-enkephalin is a neuropeptide whose release into the circulation is enhanced by stress. There have been no studies on the effects of peripherally administered Met-enkephalin in chickens.

Methods: The effects of peripheral administration of Met-enkephalin on the stress response in chickens were investigated measuring plasma concentrations of corticosterone and Met-enkephalin, together with expression of pro-enkephalin (PENK) and delta-opioid binding in the hypothalamus, anterior pituitary and adrenal glands.

Results: Administration of Met-enkephalin was followed by decreases in the basal and stressed plasma concentrations of the principal glucocorticoid, corticosterone, in chickens. In addition, the increase in plasma concentrations of corticosterone evoked by restraint stress was markedly decreased when the birds were treated with Met-enkephalin. Administration of Met-enkephalin was followed by decreases in PENK expression; hypothalamic, anterior pituitary, and adrenal delta-opioid binding; and plasma concentrations of total Met-enkephalin (peptides containing Met-enkephalin motifs). There were negative relationships between plasma concentrations of corticosterone and Met-enkephalin and between those of native Met-enkephalin and total Met-enkephalin.

Discussion: The ability of Met-enkephalin to attenuate the stress response of corticosterone, and probably other glucocorticoids, is novel and opens up several new lines of inquiry, including its site of action and its source.

[This corrects the article DOI: 10.3389/fphys.2025.1720244.].

Heat stress (HS) possesses a significant threat to poultry production systems, compromising bird health, performance, and profitability. As the egg industry transitions from conventional cage systems to cage-free (CF) systems, understanding the physiological and production impacts of HS is important. This study evaluated the effects of chronic cyclic HS on egg production, egg quality, blood biochemical parameters and shell gland gene expression in commercial laying hens raised in CF housing system. A total of 240 Hy-Line W-36 hens (26 weeks old) were randomly assigned to thermoneutral (TN, 22 °C) or HS conditions (35 °C for 12 h/day, 22 °C for 12 h/day) for 8 weeks. Each treatment included six pens (20 hens/pen; 0.139 m²/hen). Body weight, feed intake, and body temperature were measured weekly; egg production and quality were recorded throughout the trial; and blood samples and shell gland tissues were collected at the end of the trial for biochemical and gene expression analyses. Chronic HS significantly (p < 0.05) reduced body weight and feed intake, with HS birds weighing approximately 82 g less per bird and consuming about 27 g less feed/bird/day, however feed conversion ratio remained similar between TN and HS groups. HS caused a reduction in egg production (%) during the first 3 weeks of the experiment, after which the egg production stabilized and became comparable between the TN and HS groups. The HS hens laid significantly (p < 0.001) lighter eggs with weaker shell breaking strength compared with the TN group. Additionally, chronic HS decreased (p < 0.05) blood pH, while increasing partial pressure of carbon dioxide (PCO₂), and ionized calcium (iCa) levels. The expression of key shell gland genes involved in mineralization, including calbindin 1 (CALB1), solute carrier family 4 member 9 (SLC4A9), and osteopontin (OPN) was downregulated in HS chickens. Collectively, these findings indicate that chronic HS negatively impacted layer performances and eggshell quality in CF housing, likely through disruptions in blood biochemical homeostasis and shell gland gene expression.