1.Perioperative immune dynamics and clinical outcomes in patients undergoing on-pump cardiac surgery
Zhiyuan CHENG ; Xinyi LIAO ; Juan WU ; Ping YANG ; Tingting WANG ; Qinjuan WU ; Wentong MENG ; Zongcheng TANG ; Jiayi SUN ; Jia TAN ; Jing LIN ; Dan LUO ; Hao WANG ; Chaonan LIU ; Jiyue XIONG ; Liqin LING ; Jing ZHOU ; Lei DU
Chinese Journal of Blood Transfusion 2026;39(1):31-43
Objective: To characterize perioperative dynamic changes in immune-cell phenotypes and inflammatory cytokines in patients undergoing CPB (cardiopulmonary bypass) cardiac surgery, and to explore their associations with postoperative outcomes. Methods: In this prospective cohort study, 120 adult patients who underwent elective cardiac surgery under CPB at West China Hospital from May 2022 to March 2023 were enrolled. Perioperative immune-cell phenotypes and concentrations of 40 inflammation-related cytokines were measured. The primary outcomes were the sequential organ failure assessment (SOFA) score at 24 h after surgery and ΔSOFA (the peak SOFA score within 48 h after surgery minus the preoperative SOFA score). Secondary outcomes included major adverse cardiovascular events (MACE), acute kidney injury (AKI), respiratory failure, severe liver injury, and infection. Results: The mean age of enrolled patients was 57±10 years. Of these, 52% (62/120) were male and 90% (108/120) underwent valve surgery. During the rewarming to the end of CPB, neutrophil counts rapidly increased (7.39×10
/L vs preoperative 3.07×10
/L, P<0.001), with significant upregulation of CD11b (7.30×10
/L vs preoperative 3.05×10
/L, P<0.001) and CD54 (7.15×10
/L vs preoperative 2.99×10
/L, P<0.001). Lymphocyte counts increased at the end of CPB (1.75×10
/L vs preoperative 1.12×10
/L, P<0.001) but decreased significantly at 24 h after surgery (0.59×10
/L vs preoperative 1.12×10
/L, P<0.001). Plasma analysis showed that multiple pro-inflammatory cytokines increased during CPB and remained elevated up to 24 h after surgery; five chemokines and the anti-inflammatory cytokine IL-10 peaked at the end of CPB. The SOFA score increased from 1 (1, 2) preoperatively to 7 (5, 10) at 24 h after surgery, with a ΔSOFA of 6 (4, 8). Within 30 days after surgery, 48 patients (40.0%) developed AKI, 17 (14.2%) developed infection, 4 (3.3%) developed severe liver injury, 3 (2.5%) developed respiratory failure, and 3 (2.5%) experienced MACE. During the 2-year follow-up, 8 patients (6.7%) experienced MACE and 5 (4.2%) died. Conclusion: Multi-organ dysfunction is common after cardiac surgery under CPB (median ΔSOFA, 6), accompanied by perioperative activation of multiple immune-cell subsets and upregulation of pro-inflammatory, anti-inflammatory, and chemotactic mediators. This study provides data-driven evidence and research clues for further investigation of the associations between CPB-related immune perturbations and postoperative organ dysfunction and clinical outcomes.
2.Comparative Study on Effect of Jingui Shenqiwan and Liuwei Dihuangwan on Reproductive Ability and Brain Function of Normal Mice
Hong SUN ; Fan LEI ; Chenggong LI ; Rui LUO ; Shixian HU ; Bin REN ; Juan HAO ; Yi DING ; Lijun DU
Chinese Journal of Experimental Traditional Medical Formulae 2026;32(2):1-14
ObjectiveTo explore the effects of Jingui Shenqiwan (JSW) and Liuwei Dihuangwan (LDW) on the reproductive ability and brain function of normal mice and compare the actions of the two medications. MethodsSeven groups of female and male mice were divided at a ratio of 2∶1. Except for the control group, the other six groups were as follows: a group of both males and females receiving JSW (3.0 g·kg-1), a group of both males and females receiving LDW (4.5 g·kg-1), a group of males receiving water and females receiving JSW, a group of males receiving water while females receiving LDW, a group of females receiving water while males receiving JSW, and a group of females receiving water while males receiving LDW. Each group was administered the drug for 14 days and then caged together at a 2∶1 (female∶male) ratio to detect the number of pregnant mice and calculate the pregnancy rate. Pregnant mice continued receiving the drug until they naturally gave birth, which was followed by the observation of newborn mice, calculation of their average number, and the measurement of the offspring's preference for sugar water and neonatal recognition index. At the end of the experiment, the weights of the thymus and spleen were measured to calculate the organ coefficients, and mRNA or protein expression was analyzed in the brain and testes or ovaries. A 1% sucrose solution was used to examine the euphoria of their brain reward systems, while novel object recognition test (NOR) was applied to assess their memory capabilities. mRNA expression was detected using real-time quantitative polymerase chain reaction (Real-time PCR) assay, and protein expression was analyzed with Western blot. ResultsCompared with the control group, oral administration of JSW to both male and female mice for 14 days significantly increased the pregnancy rate of female mice on day 2 after being caged together (P<0.05), while LDW showed a trend but no statistical significance. Additionally, compared with the control group, JSW could upregulate the gene expression of gonadotropin-releasing hormone (GnRH) in the thalamus, as well as reproductive stem cell factor (SCF) and tyrosine kinase receptor (c-Kit) in the testes and reproductive stem cell marker mouse vasa homologue (MVH) in the ovaries, upregulate the expression of proteins influencing neuronal functional activity, such as brain-derived neurotrophic factor (BDNF), in hippocampal neurons (P<0.05), and enhance sucrose preference in male mice (P<0.05). Compared with the control group, JSW significantly increased sucrose preference and novel object recognition index in offspring mice (P<0.05), which was related to the upregulation of hippocampal dopamine D1 receptor (D1R) and N-methyl-D-aspartate receptor (Nmdar) gene expression. Compared with the control group, both JSW and LDW could upregulate the protein expression of glucocorticoid receptor (GR), BDNF, and tyrosine kinase receptor B (TrkB) in the hippocampus of offspring mice (P<0.05). ConclusionJSW significantly enhances the reproductive ability of normal mice, which is not only related to the release of gonadotropin but also associated with its regulation of brain function. Additionally, JSW has a certain regulatory effect on the brain function of the offspring mice.
3.Exploring Vascular Recruitment in Tracheobronchial Adenoid Cystic Carcinoma from Perspective of Abnormal Collateral
Jun TENG ; Lei LI ; Junyan XIA ; Yi LUO ; Qinyan HONG ; Shuiping CHEN ; Hongwu WANG
Chinese Journal of Experimental Traditional Medical Formulae 2025;31(6):260-269
Tracheobronchial adenoid cystic carcinoma (TACC) is a low-grade malignant tumor originating from the airway mucosa. Despite its slow progression,it is characterized by high invasiveness,frequent recurrence,and a strong tendency for metastasis. Preclinical studies have shown that vascular-targeted therapy holds significant potential. However,an effective systemic treatment for TACC has not been established yet. This study explored TACC from the perspective of "Feiji" in traditional Chinese medicine (TCM) as the starting point. It deeply investigated the mechanisms of abnormal collaterals and tumor vascular recruitment and further elaborated on the theoretical connection between abnormal collaterals and tumor vascular recruitment. Firstly,collateral hyperactivity led to disordered and erratic pulmonary collaterals. Their abnormal structures were similar to the disorderly and tortuous nature of tumor (pseudo)angiogenesis. This resulted in imbalances in the functions of circulation,perfusion,and reverse injection of the pulmonary collaterals,and then led to unrestrained collateral dysfunction and the accumulation of pathogenic factors. Secondly,the remodeling of the extracellular matrix (ECM) and epithelial-mesenchymal transition (EMT) in TACC were critical processes in vascular co-option (VCO),representing the micro-level manifestation of the displacement of nutrient and defense. During this process,ECM remodeling made TACC cells more likely to hijack normal blood vessels,creating a complex vascular microenvironment conducive to tumor growth. In terms of treatment,this study proposed a TCM strategy of "regulating collaterals to expel pathogenic factors and nourishing collaterals to strengthen the healthy Qi",and listed potential TCM. These were intended to regulate the Qi and blood in the collaterals,repair the functions of abnormal collaterals,and intervene in the vascular recruitment process of TACC. Future research should focus on improving the TCM clinical syndrome characteristics of TACC. Through modern molecular biology techniques,it is necessary to deeply analyze the micro-level pattern of vascular recruitment in TACC. This would enrich the understanding of the profound connection between abnormal collaterals and tumor vascular recruitment,providing empirical evidence for TCM-targeted therapies for vascular recruitment in TACC.
4.Effect of Shenge Bushen Capsules and Its Polysaccharides and Flavonoids on Precocious Puberty in Young Mice
Hong SUN ; Fan LEI ; Chenggong LI ; Shixian HU ; Weihua WANG ; Bin REN ; Juan HAO ; Rui LUO ; Lijun DU
Chinese Journal of Experimental Traditional Medical Formulae 2025;31(1):95-103
ObjectiveTo explore the effect of Shenge Bushen Capsules (SBC) on sexual development in normal 3-week-old mice. MethodsThe experiment consisted of two parts. In the first part, mice were divided into four groups: The control group and the low, medium, and high-dose SBC groups (234.7, 469.4, 938.7 mg·kg-1, respectively). In the second part, mice were divided into four groups: Control group, Pseudostellariae Radix polysaccharide (PRP) group, total flavonoids group, and SBC group, all receiving a dose of 469.4 mg·kg-1. After 7 days of administration, the vaginal opening of female mice and the descent of testes and scrotum in male mice, as well as the ovarian and testicular organ indices, were observed. After 4 weeks of administration, female and male mice were housed together for 2 days, and the pregnancy rate of females was monitored. After delivery, the pregnant female mice continued receiving the treatment for 4 weeks, and the sexual development of their offspring, including vaginal opening, testicular descent, and organ indices of ovaries and testes, was observed. Serum sex hormones were measured by enzyme-linked immunosorbent assay (ELISA), and the expression of gonadotropin-releasing hormone (GnRH) and growth hormone (GH) proteins in the hypothalamus was assessed by Western blot. ResultsCompared with the control group, there was no significant effect on the vaginal opening of female mice or the descent of testes in male mice after 7 days of SBC administration. After 4 weeks of administration, the pregnancy rate in the low-dose group was significantly reduced (P<0.05), but no significant effects were observed in the other groups. The three doses of SBC did not significantly affect the ovarian or testicular organ indices, and there was no significant upregulation in the expression of GnRH or GH in the hypothalamus. The primary component of SBC, Pseudostellariae Radix polysaccharide, significantly reduced the vaginal opening in female mice after 7 days of administration (P<0.05). After 4 weeks, the serum estradiol levels of non-pregnant female mice were decreased (P<0.05), but there was no significant effect on the expression of GnRH or GH proteins in the hypothalamus of either male or female mice. Additionally, there were no significant effects on precocious puberty indicators, such as vaginal opening and testicular descent, in the offspring mice. ConclusionSBC does not significantly promote precocious puberty in young mice, and it does not have any noticeable effects on the pregnancy rate of adult mice or the sexual development of their offspring.
5.Proteomic analysis of differentially expressed proteins in mice plasma following FLASH and conventional dose rate whole-lung irradiation
Hui LUO ; Liuxiang WANG ; Ron LEAVITT ; Jackie ROMERO ; Marie-Catherine VOZENIN ; Aymeric ALMEIDA ; Chengliang YANG ; Na LI ; Xuenan WANG ; Ronghu MAO ; Leijie MA ; Hongchang LEI ; Hong GE
Chinese Journal of Radiological Medicine and Protection 2025;45(10):941-948
Objective:To observe the tumor control and the degree of radiation-induced lung injury (RILI) between FLASH irradiation and conventional dose rate (CONV) irradiation, and compare the changes in plasma proteomic profiles of mice following whole-lung FLASH and CONV irradiation using proteomics method.Methods:A mouse model with metastatic lung cancer was established. After whole-lung irradiation, changes in normal lung capacity were monitored using CT scans. Then, a RILI model was constructed to examine pathological alterations in lung tissues following whole-lung CONV and FLASH irradiation. Plasma samples were collected from mice receiving whole-lung CONV irradiation ( n = 5) and whole-lung FLASH irradiation ( n = 5), followed by comparison with samples from the control group of healthy mice (also referred to as the healthy control group). These plasma samples were analyzed using isobaric tags for relative and absolute quantification (iTRAQ)-based proteomics, followed by the screening and identification of differentially expressed proteins using high-throughput bioinformatics. Moreover, protein-protein interaction (PPI) network analysis was conducted to identify hub genes using the STRING database and Cytoscape software. Results:Whole-lung FLASH and CONV irradiation produced consistent tumor control, with the former significantly reducing RILI compared to the latter. A total of 609 proteins were identified through proteomic analysis. Among them, 89 differentially expressed proteins were detected in the whole-lung FLASH group. Gene Ontology (GO) enrichment analysis indicated that up-regulated genes were primarily associated with stress and inflammatory responses, whereas down-regulated genes were related to ATP metabolism and angiogenesis regulation. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis revealed that up-regulated genes were predominantly enriched in unfolded protein response pathways, while down-regulated genes were mainly involved in metabolic pathways and oxidative phosphorylation. Integrated PPI analysis and subsequent validation via reverse transcription-polymerase chain reaction (RT-PCR) revealed four key genes.Conclusions:Compared to the whole-lung CONV irradiation, whole-lung FLASH irradiation reduces the RILI of normal lung tissues while maintaining equivalent tumor control in metastatic lung cancer. Proteomic analysis of differentially expressed proteins in plasma after whole-lung FLASH and CONV irradiation provides valuable insights into the molecular mechanisms underlying the FLASH effect.
6.Study on oxygen depletion and oxygen effect of FLASH irradiation
Hui LUO ; Chengliang YANG ; Paola BALLESTEROS-ZEBADUA ; Javier FRANCO-PEREZ ; Qigang YUAN ; Leijie MA ; Ronghu MAO ; Hongchang LEI ; Yanan SUN ; Shuai SONG ; Hong GE
Chinese Journal of Radiological Medicine and Protection 2025;45(11):1115-1121
Objective:To conduct a comparative analysis of the oxygen depletion and oxygen effect of FLASH irradiation and conventional irradiation by direct measurement of oxygen content.Methods:The oxygen content in different tissues and organs of mice was measured using a phosphorescent probe. A subcutaneous xenograft tumor model in mice was established, to receive electron-beam irradiation at different doses and dose rates. The oxygen depletion of tumor and normal tissue was analyzed, and tumor control was evaluated. The oxygen depletion of conventional irradiation and FLASH irradiation was further analyzed using an in vitro model. The survival fraction (SF) of normal cells after conventional irradiation and FLASH irradiation was calculated using colony formation assay under different partial pressures of oxygen, and the data were fitted to the oxygen enhancement ratio (OER) curve. Results:The mean oxygen content of subcutaneous xenograft tumor in mice was 1.28%, suggesting hypoxia. The mean oxygen content of normal tissue ranged from 3.51% to 6.53%, suggesting physioxia. In animal experiments, oxygen depletion was not observed during conventional irradiation. High-dose-rate (20 Gy/s) and ultra-high-dose-rate (FLASH, 40 Gy/s) irradiation produced oxygen depletion. During FLASH irradiation, with the increase of oxygen content, the oxygen depletion was 0.1-0.2 mm Hg/Gy for tumor tissue and 0.19-0.21 mm Hg/Gy for skin tissue, which tended to stabilize. FLASH irradiation maintained equivalent tumor control compared to conventional irradiation. The tumoricidal effect was significantly enhanced with the increase of oxygen content in the tissue ( t=3.46, P<0.01). In in vitro experiments, the mean oxygen depletion rate was about 0.16 mm Hg/Gy for conventional irradiation and 0.16-0.18 mm Hg/Gy for FLASH irradiation, which did not change significantly with the increase of oxygen content. FLASH irradiation was associated with an oxygen effect. When the partial pressure of oxygen decreased from physioxia to hypoxia, the OER value significantly reduced. Conclusions:Normal tissues and organs are in physioxia, which exhibits a lower oxygen content than that in the air. FLASH irradiation can consume a proportion of oxygen, producing an oxygen effect. When oxygen content decreases, the oxygen depletion rate slows down after FLASH irradiation.
7.Inhibition of influenza A virus replication in vitro by human β-defensin 3 based on mitophagy pathway
Yijin ZHANG ; Lijaun AN ; Qi LEI ; Hong LUO ; Yan JIANG
Chinese Journal of Nosocomiology 2025;35(11):1601-1606
OBJECTIVE To investigate the inhibitory effect of human β defensin-3(HBD3)on the replication of in-fluenza A virus(IAV)[A/PR/8/34(H1N1)virus strain]in human bronchial epithelial cells(BEAS-2B)via the mitochondrial autophagy pathway.METHODS BAS-2B cells were infected with IAV,and cell condition observa-tion:plaque assay and light microscopy.Drug treatment:HBD3,autophagy agonist rapamycin(Rapa),autoph-agy inhibitor LY294002;The expression levels of TUFM、MAVS、NP、M2 and PB1-F2 genes were detected by real-time fluorescence quantitative polymerase chain reaction(qPCR).Western blot was used to detect the protein expression levels of P62、LC3Ⅱ and LC3Ⅰ.RESULTS Plaque formation experiments showed that the number of plaques increased with the increase of viral titer.With the increase of viral titer or the prolongation of infection time,the expres-sion levels of TUFM,MAVS,NP,M2 and PB1-F2 genes in BEAS-2 B cells gradually increased,the expression levels of P62 protein decreased,and the protein expression levels of LC3Ⅱ/LC3Ⅰ increased(P<0.05).Forty-eight hpi of BE-AS-2B cells with IAV,the number of cells in the IAV group was significantly lower than that in the IAV+HBD3 group,the intercellular space was enlarged,and the cells shrunk significantly.Compared with the IAV group,the expression lev-els of TUFM,MAVS,NP,M2 and PB1-F2 genes in BEAS-2B cells in the IAV+HBD3 group decreased,the expres-sion levels of P62 protein increased,and the protein levels of LC3Ⅱ/LC3Ⅰ decreased(P<0.05).Gene expression levels of TUFM,MAVS,NP,M2 and PB1-F2 were in the IAV+Rapa+HBD3 group were lower than those in the IAV+Ra-pa group(P<0.05).The protein expression level of P62 in the IAV+Rapa+HBD3 group was higher than that in the IAV+Rapa group(P<0.05).The protein expression levels of LC3Ⅱ/LC3Ⅰ were lower in the IAV+Rapa+HBD3 group than in the IAV+Rapa group(P<0.05).CONCLUSION With the increase of viral titer or the prolongation of in-fection time,the proliferation of IAV in BEAS-2B cells increases,and the cell damage exacerbates.HBD3 can inhibit the replication of IAV after its entry into the cells;HBD3 can protect host cells and inhibit IAV replication by inhibiting MA-VS,TUFM-mediated mitophagy pathways.
8.Clinical characteristics of 22 patients with neurobrucellosis
Lei ZOU ; Qingfeng GAO ; Huijiao XU ; Hong WU ; Yao CHENG ; Luo SUN ; Yan ZHANG ; Jingyao LIU ; Baiqiang ZHANG ; Shuning SUI
Chinese Journal of Endemiology 2025;44(8):674-678
Objective:To learn about the clinical characteristics of patients with neurobrucellosis (NB) and provide references for clinical diagnosis and treatment of NB.Methods:The clinical data of 22 NB patients diagnosed and treated at Beidahuang Industry Group General Hospital from January 2018 to November 2024 and 178 healthy individuals undergoing physical examinations during the same period were retrospectively collected. The epidemiological characteristics, clinical manifestations, laboratory tests, treatment and prognosis of NB patients were analyzed.Results:Among the 22 NB patients, 12 were males (54.55%) and 10 were females (45.45%). The age was (51.77 ± 12.75) years old, ranging from 27 to 80 years old. Most of the patients were farmers (95.45%, 21/22), and 16 cases (72.73%) had contacted with cattle/sheep. The onset seasons were mainly in summer (40.91%, 9/22) and spring (31.82%, 7/22). Among all NB patients, there were 10 cases of encephalitis/meningoencephalitis, 9 cases of myelitis, and 3 cases of meningitis. The general symptoms were mainly fever (68.18%, 15/22), the neurological symptoms were mainly nausea and vomiting (36.36%, 8/22), and the physical signs were mainly muscle weakness (50.00%, 11/22) and pathological signs (45.45%, 10/22). The laboratory test results showed that the levels of hemoglobin, hematocrit, C-reactive protein, total protein, albumin, γ-glutamyl transpeptidase, α-hydroxybutyric acid dehydrogenase, lactate dehydrogenase, and glutathione reductase in NB patients were significantly different from those in healthy individuals ( P < 0.001). Brain magnetic resonance imaging revealed ischemic changes in 5 cases (22.73%), abnormal brain signals in 2 cases (9.09%), and demyelinating lesions in white matter in 1 case (4.55%). After treatment, 18 NB patients were followed up and showed good prognosis, with only 2 cases exhibiting varying degrees of sequelae (walking disorders or memory impairment). Conclusions:The clinical manifestations of NB patients are diverse. A comprehensive judgment should be made by combining epidemiological characteristics, clinical manifestations, laboratory tests and imaging examinations.
9.Proteomic analysis of differentially expressed proteins in mice plasma following FLASH and conventional dose rate whole-lung irradiation
Hui LUO ; Liuxiang WANG ; Ron LEAVITT ; Jackie ROMERO ; Marie-Catherine VOZENIN ; Aymeric ALMEIDA ; Chengliang YANG ; Na LI ; Xuenan WANG ; Ronghu MAO ; Leijie MA ; Hongchang LEI ; Hong GE
Chinese Journal of Radiological Medicine and Protection 2025;45(10):941-948
Objective:To observe the tumor control and the degree of radiation-induced lung injury (RILI) between FLASH irradiation and conventional dose rate (CONV) irradiation, and compare the changes in plasma proteomic profiles of mice following whole-lung FLASH and CONV irradiation using proteomics method.Methods:A mouse model with metastatic lung cancer was established. After whole-lung irradiation, changes in normal lung capacity were monitored using CT scans. Then, a RILI model was constructed to examine pathological alterations in lung tissues following whole-lung CONV and FLASH irradiation. Plasma samples were collected from mice receiving whole-lung CONV irradiation ( n = 5) and whole-lung FLASH irradiation ( n = 5), followed by comparison with samples from the control group of healthy mice (also referred to as the healthy control group). These plasma samples were analyzed using isobaric tags for relative and absolute quantification (iTRAQ)-based proteomics, followed by the screening and identification of differentially expressed proteins using high-throughput bioinformatics. Moreover, protein-protein interaction (PPI) network analysis was conducted to identify hub genes using the STRING database and Cytoscape software. Results:Whole-lung FLASH and CONV irradiation produced consistent tumor control, with the former significantly reducing RILI compared to the latter. A total of 609 proteins were identified through proteomic analysis. Among them, 89 differentially expressed proteins were detected in the whole-lung FLASH group. Gene Ontology (GO) enrichment analysis indicated that up-regulated genes were primarily associated with stress and inflammatory responses, whereas down-regulated genes were related to ATP metabolism and angiogenesis regulation. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis revealed that up-regulated genes were predominantly enriched in unfolded protein response pathways, while down-regulated genes were mainly involved in metabolic pathways and oxidative phosphorylation. Integrated PPI analysis and subsequent validation via reverse transcription-polymerase chain reaction (RT-PCR) revealed four key genes.Conclusions:Compared to the whole-lung CONV irradiation, whole-lung FLASH irradiation reduces the RILI of normal lung tissues while maintaining equivalent tumor control in metastatic lung cancer. Proteomic analysis of differentially expressed proteins in plasma after whole-lung FLASH and CONV irradiation provides valuable insights into the molecular mechanisms underlying the FLASH effect.
10.Study on oxygen depletion and oxygen effect of FLASH irradiation
Hui LUO ; Chengliang YANG ; Paola BALLESTEROS-ZEBADUA ; Javier FRANCO-PEREZ ; Qigang YUAN ; Leijie MA ; Ronghu MAO ; Hongchang LEI ; Yanan SUN ; Shuai SONG ; Hong GE
Chinese Journal of Radiological Medicine and Protection 2025;45(11):1115-1121
Objective:To conduct a comparative analysis of the oxygen depletion and oxygen effect of FLASH irradiation and conventional irradiation by direct measurement of oxygen content.Methods:The oxygen content in different tissues and organs of mice was measured using a phosphorescent probe. A subcutaneous xenograft tumor model in mice was established, to receive electron-beam irradiation at different doses and dose rates. The oxygen depletion of tumor and normal tissue was analyzed, and tumor control was evaluated. The oxygen depletion of conventional irradiation and FLASH irradiation was further analyzed using an in vitro model. The survival fraction (SF) of normal cells after conventional irradiation and FLASH irradiation was calculated using colony formation assay under different partial pressures of oxygen, and the data were fitted to the oxygen enhancement ratio (OER) curve. Results:The mean oxygen content of subcutaneous xenograft tumor in mice was 1.28%, suggesting hypoxia. The mean oxygen content of normal tissue ranged from 3.51% to 6.53%, suggesting physioxia. In animal experiments, oxygen depletion was not observed during conventional irradiation. High-dose-rate (20 Gy/s) and ultra-high-dose-rate (FLASH, 40 Gy/s) irradiation produced oxygen depletion. During FLASH irradiation, with the increase of oxygen content, the oxygen depletion was 0.1-0.2 mm Hg/Gy for tumor tissue and 0.19-0.21 mm Hg/Gy for skin tissue, which tended to stabilize. FLASH irradiation maintained equivalent tumor control compared to conventional irradiation. The tumoricidal effect was significantly enhanced with the increase of oxygen content in the tissue ( t=3.46, P<0.01). In in vitro experiments, the mean oxygen depletion rate was about 0.16 mm Hg/Gy for conventional irradiation and 0.16-0.18 mm Hg/Gy for FLASH irradiation, which did not change significantly with the increase of oxygen content. FLASH irradiation was associated with an oxygen effect. When the partial pressure of oxygen decreased from physioxia to hypoxia, the OER value significantly reduced. Conclusions:Normal tissues and organs are in physioxia, which exhibits a lower oxygen content than that in the air. FLASH irradiation can consume a proportion of oxygen, producing an oxygen effect. When oxygen content decreases, the oxygen depletion rate slows down after FLASH irradiation.

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