ObjectiveTo investigate the molecular mechanisms by which salvianolic acid B （SalB） inhibits epithelial-mesenchymal transition （EMT） in non-small cell lung cancer （NSCLC） by downregulating phosphoribosylaminoimidazole carboxylase and phosphoribosylaminoimidazole succinocarboxamide synthetase （PAICS） expression. MethodsNSCLC A549 cells and normal bronchial epithelial cells （bronchial epithelium transformed with Ad12-SV40 2B， BEAS-2B） were used as models. Cell viability was assessed using the cell counting kit-8 （CCK-8） assay after treatment with SalB （0， 50， 100， 200， 300， 400， 500 μmol·L^-1 for 24 or 48 h to determine effective and safe intervention concentrations. Cell proliferation， cell cycle distribution， and apoptosis were evaluated by 5-ethynyl-2′-deoxyuridine （EdU） staining and flow cytometry， respectively. Wound healing and Transwell invasion assays were performed to assess cell migration and invasion. RNA sequencing combined with bioinformatic analysis was conducted to identify differentially expressed genes and functional enrichment. Molecular docking was used to predict the binding ability between SalB and PAICS， and the cellular thermal shift assay （CETSA） was performed to evaluate the effect of SalB on the thermal stability of the PAICS protein. Western blot （WB） was used to detect the effects of SalB on PAICS and EMT-related proteins （E-cadherin， N-cadherin， Vimentin， Snail， and Slug）. A functional rescue assay was conducted by PAICS overexpression via plasmid transfection. ResultsCompared with the control group， SalB inhibited A549 cell viability in a dose-dependent manner （P<0.05）， and the effective concentrations （≤300 μmol·L^-1） showed no significant cytotoxicity in BEAS-2B cells. Within this concentration range， SalB significantly inhibited A549 cell proliferation， migration， and invasion， and induced G₀/G₁ phase arrest and apoptosis （P<0.05）. Transcriptomic analysis showed that SalB significantly downregulated PAICS expression， and its functions were enriched in cell proliferation and EMT. Bioinformatic analysis indicated that PAICS is highly expressed in lung adenocarcinoma and is associated with poor prognosis （P<0.01）. Molecular docking showed that SalB has strong binding ability to PAICS （binding energy -9.1 kcal·mol^-1. CETSA results showed that SalB significantly increased the thermal stability of the PAICS protein （P<0.05）. WB results showed that， compared with the control group， SalB dose-dependently downregulated PAICS expression， upregulated E-cadherin， and downregulated N-cadherin， Vimentin， Snail， and Slug （P<0.05）. Functional rescue experiments showed that， compared with the empty vector group， PAICS overexpression significantly enhanced A549 cell proliferation， migration， and invasion， promoted cell cycle progression， and inhibited apoptosis （P<0.05）. Meanwhile， compared with the empty vector + SalB-H group， PAICS overexpression partially reversed the inhibitory effects of SalB on malignant phenotypes and EMT-related proteins （N-cadherin， Vimentin， Snail， and Slug）， and downregulated E-cadherin expression （P<0.05，P<0.01）， indicating that PAICS is a key functional target mediating the antitumor effects of SalB. ConclusionSalB effectively inhibits EMT progression and cell cycle progression in A549 cells by downregulating PAICS expression， thereby exerting anti-NSCLC effects. This study not only reveals that PAICS is a key functional target through which SalB regulates EMT， but also provides experimental evidence supporting SalB as a potential candidate drug for inhibiting NSCLC metastasis.

ObjectiveTo investigate the mechanisms by which eupatilin （Eup） inhibits proliferation， invasion， and metastasis of non-small cell lung cancer （NSCLC） through the enhancer of zeste homolog 2/histone H3 lysine 27 trimethylation （EZH2/H3K27me3） signaling pathway. MethodsIn vivo， a subcutaneous xenograft tumor model was established in nude mice using H1299 cells to evaluate the anti-NSCLC effects of Eup. Immunohistochemistry （IHC-P） was used to detect the expression of proliferation- and invasion/metastasis-related proteins， including proliferating cell nuclear antigen （PCNA）， matrix metalloproteinase-2 （MMP-2）， matrix metalloproteinase-9 （MMP-9）， and vascular endothelial growth factor A （VEGFA）. In vitro， cell counting kit-8 （CCK-8） assays were performed to determine the viability of H1299 cells treated with different concentrations of Eup （0-200 μmol·L^-1） and to select appropriate concentrations. Colony formation and 5-ethynyl-2′-deoxyuridine （EdU） assays were used to evaluate cell proliferation. Wound healing and invasion assays were conducted to assess cell migration and invasion. Human umbilical vein endothelial cell （HUVEC） angiogenesis assays were used to evaluate the effects of Eup on angiogenesis. Transcriptomic analysis was performed to identify the targets of Eup in H1299 cells and to explore its major functions. Molecular docking and molecular dynamics simulations were conducted to predict the binding affinity and interaction stability between Eup and its target proteins. Western blot was used to detect the effects of Eup on the expression levels of EZH2/H3K27me3 pathway-related proteins and proliferation- and invasion/metastasis-related proteins， including PCNA， MMP-2， MMP-9， and VEGFA. ResultsIn the subcutaneous xenograft model， compared with the model group， Eup treatment dose-dependently inhibited the growth of H1299 xenograft tumors， and the tumor inhibition rate was significantly increased （P<0.05）. IHC-P results showed that， compared with the model group， high-dose Eup significantly reduced the expression levels of PCNA， MMP-2， MMP-9， and VEGFA in vivo （P<0.05）. In vitro， compared with the control group， Eup inhibited the proliferation， invasion， and metastasis of NSCLC cells in a concentration-dependent manner. Transcriptomic analysis further showed that， compared with the control group， Eup significantly downregulated EZH2 expression， and its functional effects were associated with inhibition of tumor metastasis. Molecular docking and molecular dynamics simulations indicated that Eup exhibited strong binding affinity with EZH2 and stable interactions. Western blot results demonstrated that， compared with the model group， Eup significantly inhibited， in a dose-dependent manner， the expression levels of EZH2， H3K27me3， and proliferation- and invasion/metastasis-related proteins （PCNA， MMP-2， MMP-9， and VEGFA） in both in vivo and in vitro experiments （P<0.05）. In vitro， compared with the control group， overexpression of EZH2 via plasmid transfection partially reversed the inhibitory effects of Eup on the expression of key proteins involved in proliferation and invasion/metastasis in H1299 cells. ConclusionEup effectively inhibits the proliferation， migration， and invasion of H1299 cells both in vivo and in vitro. The underlying mechanism may be related to inhibition of the EZH2/H3K27me3 signaling pathway and downregulation of proliferation- and invasion/metastasis-related proteins， including PCNA， MMP-2， MMP-9， and VEGFA. Eup may serve as a potential therapeutic agent for suppressing proliferation and invasion/metastasis in NSCLC.

Lung cancer， particularly non-small cell lung cancer （NSCLC）， is the malignant tumor with the highest incidence and mortality in China and worldwide. In 2022， the global number of deaths reached 1.8 million， accounting for 18.7% of all cancer-related deaths， seriously threatening human health and life， and posing a severe challenge for prevention and treatment. Although treatment strategies for lung cancer have been continuously enriched in recent years， and progress has been made in targeted therapy and immunotherapy， long-term survival benefits remain limited due to primary or acquired drug resistance， low immune responsiveness， and chemotherapy-related toxicities. Therefore， there is an urgent need to explore safe and effective adjunctive therapeutic strategies. Traditional Chinese medicine （TCM）， with its advantages of holistic regulation and individualized syndrome differentiation， has played an increasingly prominent role in comprehensive cancer treatment. TCM holds that "Yang deficiency leads to accumulation" is a key pathogenesis of tumors. Based on the theory that "Yang transforms Qi， while Yin forms substance"， deficiency of Yang Qi results in impaired warming and transformation functions， leading to internal accumulation of Yin-cold. This is closely related to dysregulation of the immune microenvironment， "cold tumor" characteristics， and dysfunction of the neuroendocrine system in modern medicine. Accordingly， the therapeutic strategy of "warming Yang， supporting healthy Qi， and combating cancer" has gained increasing attention. In recent years， commonly used Yang-warming Chinese herbs， including Aconiti Lateralis Radix Praeparata， Zingiberis Rhizoma， Cinnamomi Cortex， Epimedii Folium， and Psoraleae Fructus， as well as their active constituents， have achieved notable progress in anti-lung cancer research by regulating multiple signaling pathways， inducing apoptosis， inhibiting metastasis， and reversing drug resistance. In addition， Yang-warming formulae such as Sini Tang and Yanghe Tang have shown promising effects in alleviating myelosuppression， improving cancer-related fatigue， managing malignant pleural effusion， and relieving cancer pain. These therapies exhibit toxicity-reducing and efficacy-enhancing effects， significantly improving patients' quality of life and survival benefits. To systematically summarize the roles and mechanisms of Yang-warming Chinese herbal medicines and compound formulae in lung cancer， this paper provides a comprehensive review of recent advances， aiming to offer insights for the clinical practice of TCM in the prevention and treatment of lung cancer.

ObjectiveTo investigate the molecular mechanisms by which salvianolic acid B （SalB） inhibits epithelial-mesenchymal transition （EMT） in non-small cell lung cancer （NSCLC） by downregulating phosphoribosylaminoimidazole carboxylase and phosphoribosylaminoimidazole succinocarboxamide synthetase （PAICS） expression. MethodsNSCLC A549 cells and normal bronchial epithelial cells （bronchial epithelium transformed with Ad12-SV40 2B， BEAS-2B） were used as models. Cell viability was assessed using the cell counting kit-8 （CCK-8） assay after treatment with SalB （0， 50， 100， 200， 300， 400， 500 μmol·L^-1 for 24 or 48 h to determine effective and safe intervention concentrations. Cell proliferation， cell cycle distribution， and apoptosis were evaluated by 5-ethynyl-2′-deoxyuridine （EdU） staining and flow cytometry， respectively. Wound healing and Transwell invasion assays were performed to assess cell migration and invasion. RNA sequencing combined with bioinformatic analysis was conducted to identify differentially expressed genes and functional enrichment. Molecular docking was used to predict the binding ability between SalB and PAICS， and the cellular thermal shift assay （CETSA） was performed to evaluate the effect of SalB on the thermal stability of the PAICS protein. Western blot （WB） was used to detect the effects of SalB on PAICS and EMT-related proteins （E-cadherin， N-cadherin， Vimentin， Snail， and Slug）. A functional rescue assay was conducted by PAICS overexpression via plasmid transfection. ResultsCompared with the control group， SalB inhibited A549 cell viability in a dose-dependent manner （P<0.05）， and the effective concentrations （≤300 μmol·L^-1） showed no significant cytotoxicity in BEAS-2B cells. Within this concentration range， SalB significantly inhibited A549 cell proliferation， migration， and invasion， and induced G₀/G₁ phase arrest and apoptosis （P<0.05）. Transcriptomic analysis showed that SalB significantly downregulated PAICS expression， and its functions were enriched in cell proliferation and EMT. Bioinformatic analysis indicated that PAICS is highly expressed in lung adenocarcinoma and is associated with poor prognosis （P<0.01）. Molecular docking showed that SalB has strong binding ability to PAICS （binding energy -9.1 kcal·mol^-1. CETSA results showed that SalB significantly increased the thermal stability of the PAICS protein （P<0.05）. WB results showed that， compared with the control group， SalB dose-dependently downregulated PAICS expression， upregulated E-cadherin， and downregulated N-cadherin， Vimentin， Snail， and Slug （P<0.05）. Functional rescue experiments showed that， compared with the empty vector group， PAICS overexpression significantly enhanced A549 cell proliferation， migration， and invasion， promoted cell cycle progression， and inhibited apoptosis （P<0.05）. Meanwhile， compared with the empty vector + SalB-H group， PAICS overexpression partially reversed the inhibitory effects of SalB on malignant phenotypes and EMT-related proteins （N-cadherin， Vimentin， Snail， and Slug）， and downregulated E-cadherin expression （P<0.05，P<0.01）， indicating that PAICS is a key functional target mediating the antitumor effects of SalB. ConclusionSalB effectively inhibits EMT progression and cell cycle progression in A549 cells by downregulating PAICS expression， thereby exerting anti-NSCLC effects. This study not only reveals that PAICS is a key functional target through which SalB regulates EMT， but also provides experimental evidence supporting SalB as a potential candidate drug for inhibiting NSCLC metastasis.

ObjectiveTo investigate the mechanisms by which eupatilin （Eup） inhibits proliferation， invasion， and metastasis of non-small cell lung cancer （NSCLC） through the enhancer of zeste homolog 2/histone H3 lysine 27 trimethylation （EZH2/H3K27me3） signaling pathway. MethodsIn vivo， a subcutaneous xenograft tumor model was established in nude mice using H1299 cells to evaluate the anti-NSCLC effects of Eup. Immunohistochemistry （IHC-P） was used to detect the expression of proliferation- and invasion/metastasis-related proteins， including proliferating cell nuclear antigen （PCNA）， matrix metalloproteinase-2 （MMP-2）， matrix metalloproteinase-9 （MMP-9）， and vascular endothelial growth factor A （VEGFA）. In vitro， cell counting kit-8 （CCK-8） assays were performed to determine the viability of H1299 cells treated with different concentrations of Eup （0-200 μmol·L^-1） and to select appropriate concentrations. Colony formation and 5-ethynyl-2′-deoxyuridine （EdU） assays were used to evaluate cell proliferation. Wound healing and invasion assays were conducted to assess cell migration and invasion. Human umbilical vein endothelial cell （HUVEC） angiogenesis assays were used to evaluate the effects of Eup on angiogenesis. Transcriptomic analysis was performed to identify the targets of Eup in H1299 cells and to explore its major functions. Molecular docking and molecular dynamics simulations were conducted to predict the binding affinity and interaction stability between Eup and its target proteins. Western blot was used to detect the effects of Eup on the expression levels of EZH2/H3K27me3 pathway-related proteins and proliferation- and invasion/metastasis-related proteins， including PCNA， MMP-2， MMP-9， and VEGFA. ResultsIn the subcutaneous xenograft model， compared with the model group， Eup treatment dose-dependently inhibited the growth of H1299 xenograft tumors， and the tumor inhibition rate was significantly increased （P<0.05）. IHC-P results showed that， compared with the model group， high-dose Eup significantly reduced the expression levels of PCNA， MMP-2， MMP-9， and VEGFA in vivo （P<0.05）. In vitro， compared with the control group， Eup inhibited the proliferation， invasion， and metastasis of NSCLC cells in a concentration-dependent manner. Transcriptomic analysis further showed that， compared with the control group， Eup significantly downregulated EZH2 expression， and its functional effects were associated with inhibition of tumor metastasis. Molecular docking and molecular dynamics simulations indicated that Eup exhibited strong binding affinity with EZH2 and stable interactions. Western blot results demonstrated that， compared with the model group， Eup significantly inhibited， in a dose-dependent manner， the expression levels of EZH2， H3K27me3， and proliferation- and invasion/metastasis-related proteins （PCNA， MMP-2， MMP-9， and VEGFA） in both in vivo and in vitro experiments （P<0.05）. In vitro， compared with the control group， overexpression of EZH2 via plasmid transfection partially reversed the inhibitory effects of Eup on the expression of key proteins involved in proliferation and invasion/metastasis in H1299 cells. ConclusionEup effectively inhibits the proliferation， migration， and invasion of H1299 cells both in vivo and in vitro. The underlying mechanism may be related to inhibition of the EZH2/H3K27me3 signaling pathway and downregulation of proliferation- and invasion/metastasis-related proteins， including PCNA， MMP-2， MMP-9， and VEGFA. Eup may serve as a potential therapeutic agent for suppressing proliferation and invasion/metastasis in NSCLC.

Lung cancer， particularly non-small cell lung cancer （NSCLC）， is the malignant tumor with the highest incidence and mortality in China and worldwide. In 2022， the global number of deaths reached 1.8 million， accounting for 18.7% of all cancer-related deaths， seriously threatening human health and life， and posing a severe challenge for prevention and treatment. Although treatment strategies for lung cancer have been continuously enriched in recent years， and progress has been made in targeted therapy and immunotherapy， long-term survival benefits remain limited due to primary or acquired drug resistance， low immune responsiveness， and chemotherapy-related toxicities. Therefore， there is an urgent need to explore safe and effective adjunctive therapeutic strategies. Traditional Chinese medicine （TCM）， with its advantages of holistic regulation and individualized syndrome differentiation， has played an increasingly prominent role in comprehensive cancer treatment. TCM holds that "Yang deficiency leads to accumulation" is a key pathogenesis of tumors. Based on the theory that "Yang transforms Qi， while Yin forms substance"， deficiency of Yang Qi results in impaired warming and transformation functions， leading to internal accumulation of Yin-cold. This is closely related to dysregulation of the immune microenvironment， "cold tumor" characteristics， and dysfunction of the neuroendocrine system in modern medicine. Accordingly， the therapeutic strategy of "warming Yang， supporting healthy Qi， and combating cancer" has gained increasing attention. In recent years， commonly used Yang-warming Chinese herbs， including Aconiti Lateralis Radix Praeparata， Zingiberis Rhizoma， Cinnamomi Cortex， Epimedii Folium， and Psoraleae Fructus， as well as their active constituents， have achieved notable progress in anti-lung cancer research by regulating multiple signaling pathways， inducing apoptosis， inhibiting metastasis， and reversing drug resistance. In addition， Yang-warming formulae such as Sini Tang and Yanghe Tang have shown promising effects in alleviating myelosuppression， improving cancer-related fatigue， managing malignant pleural effusion， and relieving cancer pain. These therapies exhibit toxicity-reducing and efficacy-enhancing effects， significantly improving patients' quality of life and survival benefits. To systematically summarize the roles and mechanisms of Yang-warming Chinese herbal medicines and compound formulae in lung cancer， this paper provides a comprehensive review of recent advances， aiming to offer insights for the clinical practice of TCM in the prevention and treatment of lung cancer.

Objective: To explore the setting of gray zone of Treponema pallidum (TP) testing by retrospective analysis of blood donors with single reagent reactive anti-TP results, so as to improve blood utilization and supply safety. Methods: Blood samples were collected from 112 blood donors previously deferred due to single reagent reactive TP antibody results between January 2020 and December 2023, and subjected to dual ELISA reagents and TPPA test. The gray zone panel analysis was performed on the two ELISA reagents currently used in our department. The detection rate at each concentration of the gray zone panle was counted, and the corresponding concentrations for C , C , and C and gray zone cut-off were calculated. Results: Among the 50 samples deferred by reagent 1, 19 were confirmed reactive and 31 non-reactive in supplementary testing. Among the 62 samples deferred by reagent 2, 12 were confirmed reactive and 50 non-reactive in supplementary testing. For reagent 1, the detection rate of was 56% for S/CO≥1 and 20% for 0.5≤S/CO<1, retrospectively. For reagent 2, the detection rate was 27% for S/CO≥1 and 12.5% for 0.5≤S/CO<1, retrospectively. The detection rate for S/CO≥1 was higher than those for 0.5≤S/CO<1 for both reagents. All the 112 samples were negative in TPPA test. The C concentration of reagent 1 was 1.51 mIU/mL, and the concentration range of C ±20% was 1.21-1.81 mIU/mL. The C concentration of reagent 2 was 1.45 mIU/mL, and the concentration range of C ±20% was 1.16-1.74 mIU/mL. The C and C concentration of both reagents were within the C ±20% range, suggesting that the gray zone cutoff for both Reagent 1 and Reagent 2 should be set at S/CO=0.8 (80% of the CO value). Conclusion: All anti-TP single reagent reactive samples with S/CO value within the gray zone was tested negative by TPPA. It is necessary to consider the rationality and necessity of establishing the gray zone, so as to ensure blood safety and improve the utilization rate of blood resources.

Malignant tumors represent a major threat to global health. Conventional anti-tumor pharmacotherapy often encounters challenges such as drug resistance, highlighting an urgent need for the development of novel therapeutic strategies. Fatty acid synthase (FASN), the key enzyme catalyzing de novo fatty acid synthesis, is subject to precise regulation at multiple levels, including transcriptional control, various post-translational modifications such as ubiquitination and phosphorylation, as well as modulation by diverse signaling pathways. Recent studies have revealed that FASN is aberrantly overexpressed in various malignant tumors and is closely associated with tumor progression and poor patient prognosis. FASN is a homodimer composed of seven functional domains that catalyzes the NADPH-dependent condensation of acetyl-CoA and malonyl-CoA to generate saturated fatty acids, primarily palmitic acid. Its stability is regulated by multiple ubiquitin ligases and deubiquitinating enzymes. Additionally, FASN is subject to upstream regulation via neural precursor cell-expressed developmentally downregulated 8 (Nedd8) modification and the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) pathway, thereby establishing a metabolic-signaling positive feedback loop. As a core executor of metabolic reprogramming, FASN promotes tumorigenesis through dual mechanisms. First, its fatty acid synthesis product, palmitate, participates in membrane phospholipid synthesis, lipid raft formation, and protein palmitoylation, thereby activating several key oncogenic signaling pathways, including PI3K/AKT/mTOR, wingless-type MMTV integration site family member (Wnt)/β‑catenin, and signal transducer and activator of transcription 3 (STAT3)/matrix metalloproteinase (MMP), leading to tumor development and progression. Second, FASN plays a pivotal role in modulating the anti-tumor functions of immune cells and remodeling the tumor immune microenvironment. Specifically, FASN enhances immune checkpoint inhibition by inducing programmed death-ligand 1 (PD-L1) palmitoylation, suppresses the activation of cytotoxic T lymphocytes and natural killer cells, and promotes the polarization of M2-type macrophages, consequently facilitating tumor immune evasion and malignant progression. Precisely due to its significant overexpression in tumor cells, its critical functional role, and its differential expression compared to normal cells, FASN has emerged as a highly promising target for anti-tumor drug development. Highly selective small-molecule inhibitors, notably represented by TVB-2640, have advanced to clinical trial stages and demonstrated favorable anti-tumor activity. Furthermore, the combination of FASN inhibitors with other chemotherapeutic agents or targeted drugs can overcome the limitations of monotherapy through synergistic effects or by resensitizing tumor cells to conventional drugs, achieving a “1+1>2” therapeutic outcome. With the advancement of modern traditional Chinese medicine (TCM), numerous active ingredients derived from TCM have been confirmed to exert anti-tumor effects by modulating FASN-related pathways. This integrated approach leverages the precision of Western medicine while simultaneously harnessing the holistic regulatory benefits of TCM to alleviate the side effects of radiotherapy and chemotherapy. Despite the promising prospects of FASN-targeted therapies, challenges remain, including tumor cell metabolic plasticity, tumor context-dependent responses, and heterogeneity. This review systematically summarizes the molecular structure, physiological functions, and mechanisms of FASN in tumorigenesis, as well as recent advances in targeted therapies. Future directions—including the precise identification of responsive patient populations using spatial transcriptomics, the development of novel combination regimens, and the active exploration of integrative strategies combining traditional Chinese and Western medicine—will facilitate the clinical translation of FASN-targeted therapies and open new avenues for improving the quality of life and prognosis of cancer patients.

ObjectiveTo evaluate the effects of Tongnaoyin on the blood-brain barrier status and neurological impairment in acute ischemic stroke （AIS） patients with the syndrome of phlegm-stasis blocking collaterals by dynamic contrast-enhanced magnetic resonance imaging （DCE-MRI）. MethodsA total of 63 patients diagnosed with AIS in the Jiangsu Province Hospital of Chinese Medicine from October 2022 to December 2023 were enrolled in this study. According to random number table method，the patients were assigned into a control group （32 cases） and an observation group （31 cases）. The control group received conventional Western medical treatment，and the observation group took 200 mL Tongnaoyin after meals，twice a day from day 2 of admission on the basis of the treatment in the control group. After 7 days of treatment，the patients were examined by DCE-MRI. The baseline data for two groups of patients before treatment were compared. The National Institute of Health Stroke Scale （NIHSS） score and modified Rankin Scale （mRS） score were recorded before treatment and after 90 days of treatment for both groups. The rKtrans，rKep，and rVe values were obtained from the region of interest （ROI） of the infarct zone/mirror area and compared between the two groups. ResultsThere was no significant difference in the NIHSS or mRS score between the two groups before treatment. After 90 days of treatment，the NIHSS and mRS scores declined in both groups，and the observation group had lower scores than the control group （P<0.05）. After treatment，the rKtrans and rVe in the observation group were lower than those in the control group （P<0.01）. ConclusionCompared with conventional Western medical treatment alone，conventional Western medical treatment combined with Tongnaoyin accelerates the repair of the blood-brain barrier in AIS patients，thereby ameliorating neurological impairment after AIS to improve the prognosis.

Objective:To develop an artificial intelligence system using fully convolutional neural networks（FCN）to assist echocardiographers in the quantitative assessment of mitral regurgitation（MR）severity.Methods:From August 2021 to June 2024，echocardiographic images of 441 patients with MR were prospectively collected from Renmin Hospital of Wuhan University and the Central Hospital of Wuhan. After screening，a total of 269 patients（4 917 frames）were included in the study. Of these，3 644 frames（128 patients）of apical four-chamber color Doppler MR flow convergence images from Renmin Hospital of Wuhan University were selected as the training/validation set，while images from 121 patients（813 frames）were used as the internal test set. Additionally，images from 20 patients（460 frames）from the Central Hospital of Wuhan were selected as the external test set. The FCN algorithm was employed to capture features and segment the MR color region on the left atrial side，simultaneously outputting the regurgitant radius（r）for the calculation of the effective regurgitant orifice area and regurgitant volume. The severity of MR was then classified according to the 2017 guidelines of the American Society of Echocardiography. The segmentation and classification performance of the model was evaluated，and the measurement results of the AI system was compared with that of both senior and junior physicians.Results:In the internal test set，the accuracy of r identification for cases classified as Grade Ⅰ to Ⅳ was 0.48，0.81，0.86，and 0.87，respectively. In the external test set，the accuracy of r identification for cases classified as Grade Ⅰ to Ⅳ was 0.60，0.77，0.64，and 0.77，respectively. The average accuracy of MR classification in the internal and external test sets was 0.91 and 0.88，respectively.Conclusions:The FCN model is capable of segmenting the left atrial side regurgitant areas in apical four-chamber heart color Doppler images，aiding physicians in obtaining quantitative assessment parameters for MR，and assisting junior physicians in accurately assessing the severity of MR.