ObjectiveCleft palate (CP) is a common congenital deformity often associated with velopharyngeal insufficiency (VPI), which disrupts the physiological coupling between respiration and speech. Conventional clinical assessments, such as nasometry and spirometry, provide limited static data and fail to visualize the dynamic spatiotemporal distribution of lung ventilation during phonation. This study introduces spatiotemporal electrical impedance tomography (ST-EIT) to evaluate speech-respiratory functional features in CP patients compared to normal controls (NC). The aim is to characterize multi-domain respiratory patterns and to validate an interpretable machine learning framework for providing objective, quantitative evidence for clinical assessment. MethodsSeventy-five participants were enrolled in this study, comprising 37 patients with surgically repaired CP and 38 healthy volunteers matched for age, gender, and body mass index (BMI). All subjects performed standardized sustained phonation tasks while undergoing synchronous monitoring with a 16-electrode EIT system and a pneumotachograph. A comprehensive feature engineering pipeline was developed to extract physiological parameters across 3 complementary domains. (1) Temporal domain: including inspiratory/expiratory phase duration (tPhase), time constants (Tau), and inspiratory-to-expiratory time ratios (TI/TE); (2) airflow domain: comprising mean flow, peak flow, and instantaneous flow at 25%, 50%, and 75% of tidal volume; and (3) spatial domain: quantifying global and regional tidal impedance variation (TIV), global inhomogeneity (GI), and center of ventilation (CoV). Extreme Gradient Boosting (XGBoost) classifiers were trained using 5 distinct data sources (Spirometry, Nasometry, Inspiratory-EIT, Expiratory-EIT, and fused ST-EIT). Model performance was rigorously evaluated via stratified 5-fold cross-validation, and Shapley additive explanations (SHAP) were employed to quantify global and local feature contributions. ResultsThe CP group exhibited a distinct respiratory phenotype compared to controls. In the temporal domain, CP patients showed significantly shorter inspiratory (1.60 s vs.1.85 s, P<0.001) and expiratory phase durations (2.45 s vs. 3.95 s, P<0.001), indicating a rapid, shallow breathing rhythm. In the airflow domain, while inspiratory flows were comparable, the CP group demonstrated significantly elevated mean and peak flows during the expiratory phase (P<0.001), reflecting compensatory respiratory effort. Spatially, CP patients presented significant ventilation redistribution, characterized by higher regional TIV in the right-anterior (ROI1) and left-posterior (ROI4) quadrants, but lower TIV in the left-anterior (ROI2) quadrant. In terms of diagnostic accuracy, the multi-modal ST-EIT model achieved the highest performance (AUC: 0.915±0.012, Accuracy: 0.843±0.019, F1-score: 0.872±0.017), substantially outperforming models based on spirometry (AUC: 0.721) or nasometry (AUC: 0.625) alone. Interpretability analysis revealed that spatial domain features were the most critical, contributing 53.4% to the model’s decision-making, followed by temporal (25.0%) and airflow (21.6%) features. ConclusionST-EIT successfully captures the temporal, airflow, and spatial deviations in CP speech respiration that are undetectable by conventional methods—specifically, rapid phase transitions, hyperdynamic expiratory airflow, and regional ventilation heterogeneity. This study validates ST-EIT as a robust, non-invasive, and radiation-free tool for characterizing speech-respiratory dysfunction, offering high clinical value for bedside screening, rehabilitation planning, and longitudinal monitoring of patients with cleft palate.

ObjectiveCleft palate (CP) is a common congenital deformity often associated with velopharyngeal insufficiency (VPI), which disrupts the physiological coupling between respiration and speech. Conventional clinical assessments, such as nasometry and spirometry, provide limited static data and fail to visualize the dynamic spatiotemporal distribution of lung ventilation during phonation. This study introduces spatiotemporal electrical impedance tomography (ST-EIT) to evaluate speech-respiratory functional features in CP patients compared to normal controls (NC). The aim is to characterize multi-domain respiratory patterns and to validate an interpretable machine learning framework for providing objective, quantitative evidence for clinical assessment. MethodsSeventy-five participants were enrolled in this study, comprising 37 patients with surgically repaired CP and 38 healthy volunteers matched for age, gender, and body mass index (BMI). All subjects performed standardized sustained phonation tasks while undergoing synchronous monitoring with a 16-electrode EIT system and a pneumotachograph. A comprehensive feature engineering pipeline was developed to extract physiological parameters across 3 complementary domains. (1) Temporal domain: including inspiratory/expiratory phase duration (tPhase), time constants (Tau), and inspiratory-to-expiratory time ratios (TI/TE); (2) airflow domain: comprising mean flow, peak flow, and instantaneous flow at 25%, 50%, and 75% of tidal volume; and (3) spatial domain: quantifying global and regional tidal impedance variation (TIV), global inhomogeneity (GI), and center of ventilation (CoV). Extreme Gradient Boosting (XGBoost) classifiers were trained using 5 distinct data sources (Spirometry, Nasometry, Inspiratory-EIT, Expiratory-EIT, and fused ST-EIT). Model performance was rigorously evaluated via stratified 5-fold cross-validation, and Shapley additive explanations (SHAP) were employed to quantify global and local feature contributions. ResultsThe CP group exhibited a distinct respiratory phenotype compared to controls. In the temporal domain, CP patients showed significantly shorter inspiratory (1.60 s vs.1.85 s, P<0.001) and expiratory phase durations (2.45 s vs. 3.95 s, P<0.001), indicating a rapid, shallow breathing rhythm. In the airflow domain, while inspiratory flows were comparable, the CP group demonstrated significantly elevated mean and peak flows during the expiratory phase (P<0.001), reflecting compensatory respiratory effort. Spatially, CP patients presented significant ventilation redistribution, characterized by higher regional TIV in the right-anterior (ROI1) and left-posterior (ROI4) quadrants, but lower TIV in the left-anterior (ROI2) quadrant. In terms of diagnostic accuracy, the multi-modal ST-EIT model achieved the highest performance (AUC: 0.915±0.012, Accuracy: 0.843±0.019, F1-score: 0.872±0.017), substantially outperforming models based on spirometry (AUC: 0.721) or nasometry (AUC: 0.625) alone. Interpretability analysis revealed that spatial domain features were the most critical, contributing 53.4% to the model’s decision-making, followed by temporal (25.0%) and airflow (21.6%) features. ConclusionST-EIT successfully captures the temporal, airflow, and spatial deviations in CP speech respiration that are undetectable by conventional methods—specifically, rapid phase transitions, hyperdynamic expiratory airflow, and regional ventilation heterogeneity. This study validates ST-EIT as a robust, non-invasive, and radiation-free tool for characterizing speech-respiratory dysfunction, offering high clinical value for bedside screening, rehabilitation planning, and longitudinal monitoring of patients with cleft palate.

The Type III Secretion System (T3SS) serves as a pivotal virulence apparatus for numerous Gram-negative bacterial pathogens, enabling them to infect both animal and plant hosts. Functioning as a molecular syringe, the T3SS directly translocates bacterial effector proteins from the bacterial cytoplasm into the interior of eukaryotic host cells. These effectors are central weapons that precisely manipulate a wide spectrum of host cellular physiological processes, ranging from cytoskeletal dynamics to immune signaling, to establish a favorable niche for bacterial survival and proliferation. Among the diverse arsenal of T3SS effectors, the YopJ family constitutes a critical group of virulence factors. Members of this family are characterized by a conserved catalytic triad structure—a hallmark of the CE clan of cysteine proteases that has been evolutionarily repurposed to confer acetyltransferase activity. A defining and intriguing feature of these enzymes is their stringent dependence on a host-derived eukaryotic cofactor, inositol hexakisphosphate (IP₆), for allosteric activation. This requirement acts as a sophisticated molecular safeguard, ensuring enzymatic activity only within the appropriate host environment, thereby preventing detrimental effects on the bacterium itself. While seminal studies on individual members such as Yersinia’s YopJ and Salmonella’s AvrA have provided deep mechanistic insights, a systematic and integrative understanding of the structure-function relationships across the entire family remains fragmented. Key questions persist regarding how a conserved catalytic core has diverged to recognize distinct host substrates in different kingdoms of life. To address this gap, this article provides a systematic review of the YopJ family, focusing on three interconnected aspects: their structural features, their catalytic mechanism, and their divergent immunosuppressive strategies in animal versus plant hosts. By conducting a comparative analysis of the sequences and resolved three-dimensional structures of three representative members (e.g., HopZ1a, PopP2, AvrA), we elucidate regions of significant variation embedded within the conserved core catalytic architecture. These variable regions, often involving surface loops and substrate-binding interfaces, are crucial determinants of target specificity and functional specialization. The functional divergence of this effector family is most apparent when comparing their modes of action in different hosts. In animal hosts, YopJ-family effectors primarily sabotage innate immune signaling pathways. They achieve this by acetylating key serine and threonine residues within the activation loops of critical kinases in the MAPK and NF‑κB pathways. This post-translational modification blocks the phosphorylation and subsequent activation of these kinases, leading to potent suppression of inflammatory cytokine production. Conversely, in plant hosts, the strategy broadens to dismantle the two-tiered plant immune system. YopJ homologs target a more diverse set of substrates, including immune-associated receptor-like cytoplasmic kinases (RLCKs), microtubule networks via tubulin acetylation (which disrupts cellular trafficking and signaling), and transcription factors central to defense gene regulation. This multi-target approach effectively suppresses both Pattern-Triggered Immunity (PTI) and Effector-Triggered Immunity (ETI). In conclusion, this synthesis aims to deepen the mechanistic understanding of YopJ family-mediated pathogenesis by integrating structural biology with cellular function across host kingdoms. Elucidating the precise molecular basis for substrate selection—how conserved platforms achieve target diversity—is a major frontier. Furthermore, this knowledge provides a vital theoretical foundation for developing novel anti-virulence strategies. Targeting the conserved IP₆-binding pocket or the catalytic acetyltransferase activity itself represents a promising avenue for designing broad-spectrum inhibitors that could disarm this critical family of bacterial effectors, potentially offering new therapeutic approaches against a range of pathogenic bacteria.

Acute respiratory distress syndrome （ARDS） is believed to primarily result from a disorder of the qi movement， with qi dysfunction occurring first， followed by changes in fluids and blood. The disease is located in the lungs， with its root in qi and pathological changes in fluids and blood， aligning with the theory of "qi loses its regulatory function， fluids and blood follow the same path". Accordingly， ARDS is divided into three stages， the early stage with qi congestion， counterflow， fluids and blood obstruction， severe stage with qi collapse， yang depletion， fluids and blood out of control）， and recovery stage with qi consumption and fluids damage， residual pathogen retention. For the corresponding treatments， in the early stage， the focus is on diffusing the lung qi， opening the block， dissol-ving phlegm， and eliminating fluid retention， using Tingli Dazao Xiefei Decoction （葶苈大枣泻肺汤） and Xuanbai Chengqi Decoction （宣白承气汤） / Shegan Mahuang Decoction （射干麻黄汤） with modifications. In the severe stage， the priority is to reinforce qi， stabilize collapse， and promote diuresis and blood circulation， with modified Zhenwu Decoction （真武汤） and Shenge Powder （参蛤散）. During recovery stage， the emphasis shifts to replenishing qi and body fluids while clearing residual pathogens， with Shashen Maidong Decoction （沙参麦冬汤） and Bufei Decoction （补肺汤）. At the same time， from the perspective of "qi loses its regulatory function， fluids and blood follow the same path"， the mechanism of prone position ventilation （PPV） is explored. It is believed that the effect of "qi reaching the blood" via PPV by restoring the qi movement and unblocking qi， blood and water retention， which offers insights for the diagnosis and treatment of ARDS with integrated traditional Chinese and western medicine.

ObjectiveTo investigate the mechanism by which Shaoyaotang regulates the miRNA-155-mediated suppressor of cytokine signaling 1 （SOCS1）/Janus kinase 1 （JAK1）/signal transducer and activator of transcription 1 （STAT1） signaling pathway and thereby affects macrophage polarization. MethodsThe cell-counting kit-8 （CCK-8） assay was used to detect the effect of drug-containing serum of Shaoyaotang at different concentrations on the viability of RAW 264.7 cells. A cell model of inflammation was established by stimulating RAW264.7 cells with lipopolysaccharide （LPS） at a concentration of 10 mg·L^-1 The modeled cells were assigned by the random number table method into seven groups： LPS-induced M1 polarization （model）， M1+miRNA-155 mimics， M1+miRNA-155 inhibitor， M1+Shaoyaotang-containing serum， M1+miRNA-155 mimics+Shaoyaotang-containing serum， M1+miRNA-155 inhibitor+Shaoyaotang-containing serum， and M1+blank serum. Enzyme-linked immunosorbent assay was employed to measure the levels of inflammatory factors ［tumor necrosis factor-α （TNF-α）， interleukin-6 （IL-6）， and interleukin-1β （IL-1β）］. Immunofluorescence assay was used to detect the expression of macrophage polarization markers ［inducible nitric oxide synthase （iNOS） and macrophage mannose receptor 1 （CD206）］. Real-time PCR was employed to measure the expression of miRNA-155 in cells. Western blot was performed to determine the protein levels of SOCS1， STAT1， and JAK1. ResultsCompared with the LPS-induced M1 polarization （model） group， the M1+miRNA-155 mimics group showed up-regulated expression of miRNA-155， JAK1， STAT1， TNF-α， IL-6， IL-1β， and iNOS （P<0.05） and down-regulated expression of CD206 （P<0.05）. In both the M1+miRNA-155 inhibitor group and the M1+Shaoyaotang-containing serum group， the expression levels of miRNA-155， JAK1， STAT1， TNF-α， IL-6， IL-1β， and iNOS were down-regulated （P<0.05）， while those of SOCS1 and CD206 were up-regulated （P<0.05）. Compared with the M1+miRNA-155 mimics group， the M1+miRNA-155 mimics+Shaoyaotang-containing serum group showed down-regulated expression of miRNA-155， JAK1， STAT1， TNF-α， IL-6， IL-1β， and iNOS （P<0.05） and up-regulated expression of SOCS1 and CD206 （P<0.05）. Compared with the M1+miRNA-155 inhibitor group， the M1+miRNA-155 inhibitor+Shaoyaotang-containing serum group showed down-regulated expression of miRNA-155， JAK1， STAT1， TNF-α， IL-6， IL-1β， and iNOS （P<0.05） and up-regulated expression of SOCS1 and CD206 （P<0.05）. ConclusionShaoyaotang regulates macrophage polarization by modulating miRNA-155 expression and interfering with the SOCS1/JAK1/STAT1 signaling pathway. The findings provide new experimental evidence for the treatment of ulcerative colitis with Shaoyaotang.

ObjectiveTo investigate the potential role and underlying mechanisms of Shaoyaotang in intervening macrophage glycolytic reprogramming in ulcerative colitis （UC）. MethodsForty-eight C57BL/6 mice were randomly divided into six groups： Normal control group， model group， mesalazine group （0.39 g·kg^-1）， Shaoyaotang group （15.54 g·kg^-1）， 2-deoxy-D-glucose （2-DG） group （glycolysis inhibitor， 100 mg·kg^-1）， and 2-DG + Shaoyaotang combined group （100 mg·kg^-1+15.54 g·kg^-1）. Except for the normal control group， mice in the other five groups were induced to establish UC models using dextran sulfate sodium （DSS）. The normal control group was administered pure water via intragastric gavage， while the other groups received intragastric gavage of mesalazine solution， intragastric gavage of Shaoyaotang， and the 2-DG group was treated with 2-DG via intraperitoneal injection. After 7 consecutive days of treatment， colonic tissues were extracted. Hematoxylin and eosin （HE） staining was performed to evaluate histopathological changes and tissue injury in the colon. Enzyme-linked immunosorbent assay （ELISA） was used to detect the expression of interleukin-10 （IL-10） and tumor necrosis factor-α （TNF-α） in colonic tissues. Western blot analysis was employed to determine the expression levels of hypoxia-inducible factor-1α （HIF-1α）， glucose transporter （GLUT1）， lactate dehydrogenase A （LDHA）， pyruvate kinase M2 （PKM2）， and 6-phosphofructo-2-kinase/fructose-2，6-biphosphatase 3 （PFKFB3） in colonic tissues. Immunofluorescence was conducted to detect the expression of CD206 and inducible nitric oxide synthase （iNOS） in colonic tissues. Liquid chromatography-mass spectrometry （LC-MS） was utilized to measure lactate and citrate levels in colonic tissues. ResultsCompared with the normal control group， mice in the model group exhibited a significant increase in disease activity index （DAI） scores， accompanied by colonic mucosal congestion， edema， and inflammatory cell infiltration， significantly elevated expression of the inflammatory cytokine TNF-α （P<0.05）， significantly decreased IL-10 expression （P<0.05）， significantly increased levels of HIF-1α， GLUT1， LDHA， PKM2， and PFKFB3 in colonic tissues （P<0.05）， markedly elevated iNOS expression （P<0.05）， significantly decreased CD206 expression （P<0.05）， and significantly elevated lactate and citrate levels in colonic tissues （P<0.05）. In contrast to the model group， the Shaoyaotang group， inhibitor group， and Shaoyaotang combined with inhibitor group demonstrated amelioration of mucosal injury in colonic tissues， markely decreased expression levels of the inflammatory cytokine TNF-α （P<0.05）， elevated IL-10 expression levels， significantly decreased expression of HIF-1α， GLUT1， LDHA， PKM2， and PFKFB3 （P<0.05）， markedly reduced iNOS expression levels （P<0.05）， significantly increased CD206 expression （P<0.05） and significantly decreased lactate and citrate levels （P<0.05）. ConclusionShaoyaotang ameliorates symptoms of DSS-induced UC in mice， and its therapeutic mechanism may be associated with regulating macrophage glycolytic reprogramming via modulation of the HIF-1α signaling pathway.

ObjectiveTo investigate the role of microRNA-155-5p （miR-155-5p） in ulcerative colitis （UC） and study the molecular mechanism of Shaoyaotang in the treatment of UC by regulating miR-155-5p. MethodsForty-eight SPF-grade male C57BL/6 mice were selected and assigned via the random number table method into 6 groups （n=8）： A blank control group， a model group， a mesalazine （0.39 g·kg^-1） group， a Shaoyaotang （31.08 g·kg^-1） group， a Janus kinase 1 （JAK1） inhibitor （baricitinib， 10 mg·kg^-1） group， and a Shaoyaotang combined with inhibitor （baricitinib 10 mg·kg^-1 + Shaoyaotang 31.08 g·kg^-1） group. After successful modeling of UC by gavage of 3% dextran sulphate sodium solution， each group received corresponding drug intervention for 7 days. Shaoyaotang and mesalazine were administered by gavage， and baricitinib by intraperitoneal injection. Twenty-four hours after the last administration， mice were anesthetized by intraperitoneal injection of pentobarbital sodium， and blood was collected for determination of white blood cell count and erythrocyte sedimentation rate （ESR）. Mice were then sacrificed for measurement of colon length. Hematoxylin-eosin staining was used to observe colonic pathological changes and perform pathological scoring. Real-time fluorescence quantitative polymerase chain reaction （Real-time PCR） was employed to determine the relative expression of miR-155-5p in the colonic tissue， and Western blot was used to determine the protein levels of JAK1， phosphorylated JAK1 （p-JAK1）， suppressor of cytokine signaling 1 （SOCS1）， signal transducer and activator of transcription 1 （STAT1）， and phosphorylated STAT1 （p-STAT1）. ResultsCompared with the blank control group， the model group showed increased disease activity index （DAI） score and pathological score， shortened colon， upregulated relative expression of miR-155-5p and protein levels of p-JAK1 and p-STAT1， downregulated protein level of SOCS1 in the colonic tissue， prolonged time of erythrocyte sedimentation， and increased white blood cell count （P<0.01）. Compared with the model group， all drug-treated groups exhibited improvements in the above indicators （P<0.01）. Moreover， the Shaoyaotang group showed better therapeutic effects than the mesalazine group in regulating miR-155-5p expression， related protein levels， DAI score， and colonic pathological score （P<0.01）. ConclusionShaoyaotang may downregulate miR-155-5p to relieve its inhibition on SOCS1， thereby suppressing the excessive activation of the JAK1/STAT1 signaling pathway and ultimately alleviating intestinal inflammatory damage.

ObjectiveTo investigate the role of the Toll-like receptor 4 （TLR4）/myeloid differentiation factor 88 （MyD88）/nuclear factor-κB （NF-κB） signaling pathway in intestinal mucosal barrier damage in ulcerative colitis， as well as the intervention mechanism of Shaoyaotang. MethodsSixty SD rats were allocated into a blank group， a model group， a mesalazine （0.42 g·kg^-1） group， and low-， medium-， and high-dose （11.1， 22.2， 44.4 g·kg^-1， respectively） Shaoyaotang groups. A model of ulcerative colitis was induced by 2，4，6-trinitrobenzenesulfonic acid （TNBS）. After successful modeling， rats were administrated with corresponding agents via gavage for 7 days. Changes in colon length and colon weight were observed. Hematoxylin-eosin staining was performed to examine the pathological changes of the colon， and immunohistochemistry was employed to detect the expression of the inflammatory cytokine interleukin-8 （IL-8）， cyclooxygenase-2 （COX-2）， junction adhesion molecule-1 （JAM-1）， and claudin-1 in the colon. Western blot analysis was performed to determine the protein levels of TLR4， MyD88， and NF-κB in the colon. ResultsCompared with the blank group， the model group showed elevated DAI score （P<0.01）， reduced colon length and colon weight （P<0.01）， down-regulated protein levels of JAM-1 and claudin-1 （P<0.01）， and up-regulated protein levels of IL-8， COX-2， TLR4， MyD88， and NF-κB p65 （P<0.01） in the colon tissue. Compared with the model group， each treatment group showed decreased DAI score （P<0.05， P<0.01）， increased colon length and colon weight （P<0.05， P<0.01）， up-regulated protein levels of JAM-1 and claudin-1 （P<0.01）， and down-regulated protein levels of IL-8， COX-2， TLR4， MyD88， and NF-κB p65 （P<0.01） in the colon tissue. ConclusionShaoyaotang alleviates intestinal inflammation and intestinal mucosal damage to protect intestinal barrier integrity by regulating the TLR4/MyD88/NF-κB signaling pathway.

ObjectiveIn nature, objects cast shadows due to illumination, forming the basis for stereoscopic perception. Birds need to adapt to changes in lighting (meaning they can recognize stereoscopic shapes even when shadows look different) to accurately perceive different three-dimensional forms. However, how neurons in the key visual brain area in birds handle these lighting changes remains largely unreported. In this study, pigeons (Columba livia) were used as subjects to investigate how neurons in pigeon’s ventrolateral mesopallium (MVL) represent stereoscopic shapes consistently, regardless of changes in lighting. MethodsVisual cognitive training combined with neuronal recording was employed. Pigeons were first trained to discriminate different stereoscopic shapes (concave/convex). We then tested whether and how light luminance angle and surface appearance of the stereoscopic shapes affect their recognition accuracy, and further verify whether the results rely on specify luminance color. Simultaneously, neuronal firing activity of neurons was recorded with multiple electrode array implanted from the MVL during the presentation of difference shapes. The response was finally analyzed how selectively they responded to different stereoscopic shapes and whether their selectivity was affected by the changes of luminance condition (like lighting angle) or surface look. Support vector machine (SVM) models were trained on neuronal population responses recorded under one condition (light luminance angle of 45°) and used to decode responses under other conditions (light luminance angle of 135°, 225°, 315°) to verify the invariance of responses to different luminance conditions. ResultsBehavioral results from 6 pigeons consistently showed that the pigeons could reliably identify the core 3D shape (over 80% accuracy), and this ability wasn’t affected by changes in light angle or surface appearance. Statistical analysis of 88 recorded neurons from 6 pigeons revealed that 83% (73/88) showed strong selectivity for specific 3D shapes (selectivity index>0.3), and responses to convex shapes were consistently stronger than to concave shapes. These shape-selective responses remained stable across changes in light angle and surface appearance. Neural patterns were consistent under both blue and orange lighting. The decoding accuracy achieves above 70%, suggesting stable responses under different conditions (e.g., different lighting angles or surface appearance). ConclusionNeurons in the pigeon MVL maintain a consistent neural encoding pattern for different stereoscopic shapes, unaffected by illumination or surface appearance. This ensures stable object recognition by pigeons in changing visual environments. Our findings provide new physiological evidence for understanding how birds achieve stable perception (“invariant neural representations”) while coping with variations in the visual field.

ObjectiveFat infiltration has been shown to be closely related to muscle mass loss and a variety of muscle diseases. This study proposes a method based on phase-angle electrical impedance tomography (ΦEIT) to visualize the electrical characteristic response caused by muscle fat infiltration, aiming to provide a new technical means for early non-invasive detection of muscle mass deterioration. MethodsThis study was divided into two parts. First, a laboratory pork model was constructed to simulate different degrees of fat infiltration by injecting1 ml or 2 ml of emulsified fat solution into different muscle compartments, and the phase angle images were reconstructed using ΦEIT. Second, a human experiment was conducted to recruit healthy subjects (n=8) from two age groups (20-25 years old and 26-30 years old). The fat content percentage η_fat of the left and right legs was measured by bioelectrical impedance analysis (BIA), and the phase angle images of the left and right calves were reconstructed using ΦEIT. The relationship between the global average phase angle Φ_M and the spatial average phase angle Φ_Mi of each muscle compartment and fat infiltration was further analyzed. ResultsIn the laboratory pork model, the grayscale value of the image increased with the increase of η_fat and Φ_M showed a downward trend. The results of human experiments showed that at the same fat content percentage, the Φ_M of the 26-30-year-old group was about 20%-35% lower than that of the 20-25-year-old group. The fat content percentage was significantly negatively correlated with Φ_M. In addition, the M₂ (soleus) compartment was most sensitive to fat infiltration, and the spatial average phase angles of the M₂ (soleus), M₃ (tibialis posterior and flexor digitorum longus), and M₄ (tibialis anterior, extensor digitorum longus, and peroneus longus) compartments all showed significant inter-group differences. ConclusionΦEIT imaging can effectively distinguish different degrees of fat infiltration, especially in deep, small or specially located muscles, showing high sensitivity, demonstrating the potential application of this method in local muscle mass monitoring and early non-invasive diagnosis.