Frontiers in Physiology最新文献

This review provides a comprehensive analysis of manganese (Mn) metabolism and its regulatory roles across multiple biological levels. By examining Mn homeostasis mechanisms, including Mn absorption, excretion, distribution, and transport across the intestines, liver, and brain, this work highlights the integrative nature of Mn physiology. Additionally, it explores routes of Mn overexposure and the consequences of Mn dysregulation on various organ systems, with a focus on neurotoxicity, as well as the genetic and environmental factors that contribute to Mn homeostasis. This review synthesizes insights into metal transporters to advance our understanding of their roles in maintaining systemic and brain Mn homeostasis under healthy conditions and their contribution to Mn dysregulation in disease states, particularly neurological disorders. By focusing on Mn transport and regulation across multiple physiological systems and its impact on health and disease, we aim to bridge the gap between molecular-level processes and whole-body physiology.

Introduction: This randomized controlled trial aimed to compare the acute and sustained effects of tissue flossing (TF) versus dynamic stretching (DS) on hamstring muscle stiffness and flexibility in light volleyball (LVB) enthusiasts.

Methods: Thirty-seven participants were randomly assigned to TF, DS, or placebo groups. Muscle stiffness was evaluated using shear-wave elastography, measuring Young's modulus at the distal and proximal regions of the biceps femoris long head and semitendinosus. Flexibility was assessed via passive knee extension (KE), straight leg raise (SLR), and forward flexion distance (FFD) at baseline, immediately post-intervention, and 30 min post-intervention.

Results: The results demonstrated that TF significantly reduced muscle stiffness compared to DS at the 30-min mark, particularly in the semitendinosus [distal: mean difference = -43.40 kPa, 95% CI (-80.65, -6.16), p = 0.007; proximal: -51.13 kPa, (-101.20, -1.05), p = 0.040]. However, no significant differences were observed between the TF and DS groups in flexibility outcomes (KE, SLR, or FFD) at any time point.

Discussion: These findings indicate that while TF offers a prolonged reduction in hamstring stiffness-suggesting potential benefits in injury prevention and prolonged performance-its effect on functional flexibility remains comparable to that of dynamic stretching. TF may serve as an effective warm-up intervention for athletes requiring sustained decreases in muscle stiffness during activities.

Background: Regulation of vascular permeability in hereditary angioedema due to C1 inhibitor deficiency (HAE-C1INH) is key to understanding the disease, but the role of the autonomic nervous system (ANS) in this mechanism remains unclear.

Purpose: The aim of this study was to compare the cardiovascular autonomic response to the head-up tilt test (HUTT) in HAE-C1INH patients and matched healthy controls (HCs).

Methods: HAE-C1INH patients were evaluated during a 1-week symptom-free period. Electrocardiogram (ECG) and beat-to-beat non-invasive arterial blood pressure (BP) were recorded in the supine position (REST) and during 70° tilt (TILT). Heart rate and systolic BP (SBP) variability indices were derived. Variance (σ² _SBP) and low-frequency power (LF_SBP) of SBP variability were used as markers of sympathetic vascular control.

Results: Twenty-five HAE-C1INH patients [13 male individuals, 44 (28.8-57.5) years] and 25 HCs [13 male individuals, 44 (30.8-54.3) years] were enrolled and divided into <45 and ≥45 age groups. Eighteen patients were on long-term prophylaxis (LTP). In the younger group, LF_SBP increased from REST to TILT in both groups, with no differences. In older subjects, HAE-C1INH patients showed higher σ² _SBP [21.2 (9.3-59.2) vs. 7.5 (1.9-14.6) mmHg²] and a greater LF_SBP increase [9.4 (4.6-22.4) vs. 0.9 (0.2-7.6) mmHg²] than HCs during TILT, suggesting sympathetic hyperactivation. No significant group differences in cardiac autonomic control were observed during REST or TILT, regardless of age. Findings in the LTP subgroup mirrored those of the full cohort.

Conclusion: Older HAE-C1INH patients display altered vascular autonomic regulation, with an exaggerated sympathetic response during orthostatic stress. Further studies are needed to assess the role of LTP in these alterations.

Clinical trial registration: https://clinicaltrials.gov/study/NCT06408805?cond=Hereditary%20Angioedema&term=autonomic&rank=1.

Background: Accurately predicting sports injuries remains a significant challenge due to the complexity of factors involved, including anatomical structures and movement mechanics. Traditional approaches often rely on single data sources and fail to provide personalized risk assessments, limiting their effectiveness.

Methodology: This study introduces a multimodal approach to predicting sports injuries by combining high resolution computed tomography (CT) scans with biomechanical data from motion capture systems, wearable inertial measurement units (IMUs), and force-sensitive insoles. CT images were denoised and contrast-enhanced before being analyzed with the Swin-UNet architecture, which captures both fine structural details and broader spatial patterns. At the same time, biomechanical signals such as joint movement, ground reaction forces, and loading patterns were processed using orthogonal component decomposition and analyzed with a Long Short-Term Memory (LSTM) network to capture changes over time. The results from both models were combined through a decision level fusion method, producing a single injury-risk score. By integrating anatomical and functional data, the framework provides a more accurate and timely assessment of injury risk, supporting early intervention and improved athlete safety.

Results: The proposed model demonstrated strong predictive performance, achieving an accuracy of 94%, precision of 91%, recall of 92%, and an F1 score of 91%. These results highlight the advantage of combining high resolution imaging with biomechanical measurements through an advanced deep learning framework, outperforming traditional methods.

Conclusion: By integrating CT imaging and biomechanical data within a Swin Unet based framework, this study offers a precise and personalized approach to sports injury prediction. The inclusion of real-time monitoring further enhances the practical value of the model, supporting early intervention and improving athlete safety and training efficiency.

Objective: To investigate whether grape seed powders (GSP) contribute to growth-promoting in aquaculture, a comprehensive analysis of the effects of GSP on grass carp (Ctenopharyngodon idella) was performed.

Methods: Six hundred grass carp were divided into four groups, including the control and the low (100 mg/kg), middle (500 mg/kg), and high (1000 mg/kg) GSP-supplemented groups. The material composition, growth parameters, physiological/biochemical indexes, and muscle nutrition were analyzed.

Results: After feeding of 60 days, the weight gain rate, specific growth rate, and condition factor of grass carp significantly increased with GSP supplementation at low and middle levels in comparison to the blank control (P < 0.05). Additionally, the catalase activities in the gill and gut significantly elevated as dietary supplementation with GSP at the low and middle levels in comparison to the blank control (P < 0.05), while the interleukins' (IL-1β, IL-4, IL-6, IL-10, and IL-12) contents in the spleen significantly decreased (P < 0.05), suggesting an enhancement in antioxidant capacity activities and a reduction in inflammation levels after supplemental feeding with GSP. The total amino acids and total fatty acids in the blank control were equivalent to these in the low GSP-supplemented group, which were inconsistent with the upregulation of total amino acids and downregulation of total fatty acids in the middle and high GSP-supplemented groups. Furthermore, pathogenic bacteria in the gut (e.g., Enterobacter hormaechei and Enterobacter cloacae) were effectively inhibited in the GSP-supplemented groups, with significant correlations to the increased amino acid (Pro) and the decreased fatty acids (e.g., C16:1n7, C18:1n9c, C20:2n6, and C22:6n3) (P < 0.05).

Conclusion: Based on the results, we confirmed that dietary supplementation with procyanidin-rich GSP at a relative low level (100 mg/kg) was beneficial for the healthy aquaculture of grass carp.

Introduction: The efficacy of nonsteroidal mineralocorticoid receptor blockers (MRBs) in inhibiting the progression of diabetic kidney disease (DKD) is well-known. However, MRB therapy often leads to hyperkalemia and remains a major concern. Recent studies suggest that combining potassium-retaining diuretics, renin-angiotensin system inhibitors, and sodium-glucose cotransporter 2 inhibitors (SGLT2i) reduces the incidence of hyperkalemia. However, how SGLT2i, specifically affecting the proximal tubule (PT), suppresses hyperkalemia is unclear. This study aimed to elucidate the interaction between the aldosterone (Ald)/mineralocorticoid receptor (MR) signaling pathway and SGLT2i specifically in the PT, focusing on the synergistic effects on PT sodium (Na⁺) and potassium (K⁺) transport activity.

Methods: We investigated the effects of Ald and SGLT2i on PT Na⁺ and K⁺ transporters. For PT Na⁺ transport function analysis, freshly isolated PTs were used to analyze luminal NHE activity and basolateral NBCe1 activity using 2',7'-bis(carboxyethyl)-5 (6)-carboxyfluorescein acetoxymethyl ester. A DKD model was established using spontaneously diabetic Torii (SDT) fatty rats. The model rats were randomly assigned to the following groups: esaxerenone (Esx) monotherapy and Esx + dapagliflozin (Dapa) therapy. We then evaluated histological parameters, K⁺ channel expression, and various biological parameters.

Results: Ald increased not only the activity of NBCe1 and NHE3 but also the expression of TWIK-1/Kcnk1 and TASK-2/Kcnk5. These stimulatory effects were completely suppressed by ESX. Rats treated with Ald alone exhibited hypertension, hyperinsulinemia, and severe kidney injury, which were ameliorated by ESX; however, these rats also presented with hyperkalemia. The ESX + Dapa therapy reduced the incidence of hyperkalemia and improved kidney injury compared to ESX alone. The expression of TWIK-1 and TASK-2 increased in rats continuously treated with Ald compared with that in control rats, whereas their expression decreased to control levels in rats continuously treated with ESX alone. TWIK-1 expression did not significantly decrease in rats continuously treated with ESX and Dapa compared with that in rats treated with ESX alone.

Discussion: The findings indicate that Ald stimulates Na⁺ transport via the MR in the PT and regulates the expression of K⁺ channel genes. The MRB and SGLT2i combination may mitigate MRB-induced hyperkalemia, potentially by regulating TWIK-1 expression and maintaining K⁺ homeostasis.

Background: The aim of this study was to describe the thermoregulatory responses of elite athletes during competitions and training of the international cross-country skiing FIS Scandinavian Cup in Finland, held under cold (subzero) ambient conditions.

Methods: The core and skin temperatures were continuously recorded during two competition formats-a 10-km race (n = 18; 10 m, 8 f) and a 20-km race (n = 14; 9 m, 5 f)-and during training (n = 11; 7 m, 4 f) using electronic temperature pills and temperature sensors fixed on the chest, arm, hand, and thigh, respectively. The heart rate and skiing speed were continuously recorded using heart rate monitors with integrated GPS technology. Ambient temperatures during the measuring period ranged from -13.0 °C to -1.3 °C.

Results: The mean core temperature (T_core) increased significantly during the 10-km classic (39.0 °C ± 0.4 °C) and the 20-km freestyle (39.2 °C ± 0.7 °C) races (all p < 0.001) and during trainings (38.3 °C ± 0.5 °C). In contrast, skin temperature decreased in all four body parts (all p < 0.001), with the greatest decreases measured on the thigh [18.7 °C ± 4.1 °C (10-km race), 20.7 °C ± 4.6 °C (20-km race), and 18.5 °C ± 3.2 °C (training)]. During both races, the heart rate significantly increased over time while the racing speed decreased (p < 0.001, respectively). The mean skin temperature of the thigh correlated with skiing speed in the 10-km (r = 0.573, p = 0.041) and the 20-km (r = 0.682, p = 0.021) races.

Conclusion: In summary, despite low ambient temperatures under real competition and training conditions, the athletes exhibited high heat generation, which enabled them to maintain a high core temperature. In contrast, the skin temperature dropped sharply during competitions and trainings. The association between the low mean skin temperature and the lower racing speed should be investigated further.

Background: Glutamate is the major excitatory neurotransmitter in the nervous system, common in neuromuscular junctions, and with abnormally reduced levels in several muscle diseases. Glutamate receptor AMPA GluR3, encoded by the GRIA3 gene, has important neurophysiological roles in regulation of neural networks, sleep, and breathing. GluR3 deletion or abnormal function increases the susceptibility to seizures and disrupts oscillatory networks of sleep, breathing, exploratory activity, and motor coordination.

Questions: Do human skeletal muscle cells express GluR3? Are they activated by glutamate? Do autoimmune GluR3B antibodies of Nodding Syndrome (NS) patients, and/or other intractable epilepsy patients, that bind and damage neural cells, also bind and affect skeletal muscle cells?

Results: We discovered several original findings: 1) Human primary skeletal muscle cells (myoblasts) express GluR3 RNA and protein, evident by PCR and immunostaining, 2) glutamate (10^-8-10^-5M) increases intracellular sodium in human skeletal muscle cells and increases muscle cell number (probably by inducing muscle cell proliferation), 3) AMPA and NMDA increase intracellular sodium in skeletal muscle cells, 4) GluR3B monoclonal antibody binds skeletal muscle cells and increases their number, 5) autoimmune affinity-purified GluR3B antibodies of epileptic NS patients, suffering from nodding due to loss of muscle tone and muscle wasting, bind skeletal muscle cells, 6) purified IgGs rich in autoimmune GluR3B antibodies of intractable epilepsy patients bind and kill skeletal muscle cells.

Possible implications: Together, the novel findings in this study may have various important implications on muscle physiology and pathology and call for continuation studies on diverse physiological, pathological and therapeutic topics. Meanwhile, we raise few hypotheses: 1) GluR3 has an important physiological role in muscle cells and motor function, 2) impaired GluR3 function (due to genetic/epigenetic/autoimmune/infectious/inflammatory factors?) can cause muscle impairments and motor problems, 3) glutamate, by direct activation of GluR3 and/or other GluRs expressed in skeletal muscle cells, can beneficially affect muscle cell survival, growth, and function, 3) Glutamate, iGluR agonists, and/or GluR3B mAb may have therapeutic effects for muscle diseases, injuries, and age-related sarcopenia, 4) autoimmune GluR3B antibodies of NS patients and/or other epilepsy patients may bind GluR3 in muscle cells, damage these cells, and induce muscle dysfunction and motor problems.