1.Mechanism of Xibining Ⅱ in alleviating cold stimulus pain sensitivity in rats with cold-damp obstruction-type KOA by regulating SETDB2/H3K9me3 signaling axis
Enrui HU ; Yibao WEI ; Deren LIU ; Maimaitituxun AOBULIAISAN ; Peimin WANG ; Taiyang LIAO
China Pharmacy 2026;37(3):324-330
OBJECTIVE To investigate the mechanism by which the traditional Chinese medicine formula Xibining Ⅱ modulates cold-stimulus pain sensitivity in rats with cold-damp obstruction-type knee osteoarthritis (KOA) based on the SET domain bifurcated histone lysine methyltransferase 2 (SETDB2)/histone H3 lysine 9 trimethylation (H3K9me3) signaling axis. METHODS Fifty SD rats were randomly divided into control group (intragastric administration and intrathecal injection of equal volumes of normal saline), model group (intragastric administration and intrathecal injection of equal volumes of normal saline), Xibining Ⅱ low- and high-dose groups (4, 8 g/kg Xibining Ⅱ, intragastric administration), and high-dose of Xibining Ⅱ+small interfering RNA (siRNA) group (8 g/kg of Xibining Ⅱ via intragastric administration and intrathecal injection of SETDB2 siRNA at 0.2 mmol/L, 20 μL per rat), with 10 rats in each group. Except for the control group, cold-damp obstruction-type KOA model was induced in other groups. Drug administration commenced 14 days post-modeling and continued for 28 days. Following the final administration, the following were assessed: behavioral changes in cold-stimulation pain sensitivity, histopathological changes in the articular cartilage of the knee joint, the contents of inflammatory factors [tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β)] and pain mediators [calcitonin gene-related peptide (CGRP), nerve growth factor (NGF)], as well as the expressions of SETDB2/H3K9me3 signaling axis,inflammatory factors and pain mediators related proteins and mRNAs in dorsal root ganglion (DRG) tissue. RESULTS After 28 days of drug administration, compared with the model group, Xibining Ⅱ low- and high-dose groups exhibited significantly prolonged cold-stimulus paw withdrawal latency (P<0.05); the number of positive responses in the acetone low-temperature test was significantly reduced (P<0.05); Mankin score and the Osteoarthritis Research Society International score for knee joint tissue, as well as the levels of inflammatory factors and pain mediators in the serum and their expression in DRG tissue were all significantly decreased (P<0.05); the protein expressions of SETDB2 and H3K9me3 in DRG tissue were significantly increased (P<0.05). Intrathecal injection of SETDB2 siRNA reversed the above effects of high-dose of Xibining Ⅱ (P<0.05). CONCLUSIONS Xibining Ⅱ may alleviate inflammatory and pain responses by activating the SETDB2/H3K9me3 signaling axis, ultimately improving cold-stimulus pain sensitivity in rats with cold-damp obstruction-type KOA.
2.Establishment and Evaluation of Different Disease-Syndrome Combination Mice Models of Knee Osteoarthritis with Cold-Dampness Stagnation Syndrome
Enrui HU ; Yibao WEI ; Deren LIU ; Aobuliaisan MAIMAITITUXUN ; Licheng ZHANG ; Jiachen SONG ; Jun MAO ; Taiyang LIAO ; Peimin WANG
Journal of Traditional Chinese Medicine 2026;67(19):2120-2129
ObjectiveTo establish and evaluate different disease-syndrome combination mice models of knee osteoarthritis (KOA) with cold-dampness obstruction syndrome, and to identify the optimal modeling method. MethodsEighty mice were randomly divided into a control group, a treadmill plus climate chamber group, an anterior cruciate ligament transection (ACLT) plus climate chamber group, an ACLT group, a destabilization of the medial meniscus (DMM) plus climate chamber group, a DMM group, an intra-articular injection plus climate chamber group, and an intra-articular injection group, with 10 mice in each group. Mice in the ACLT group underwent surgical transection of the knee anterior cruciate ligament to establish the model, while those in the DMM underwent surgical transection of the medial meniscal tibial ligament of the knee, and those in the intra-articular injection group were modeled by an intra-articular injection of 50 μl of normal saline containing 1mg of monosodium iodoacetate (MIA) into the medial side of the patellar ligament. Mice in the ACLT plus climate chamber, DMM plus climate chamber, and intra-articular injection plus climate chamber groups were placed in an artificial climate chamber (relative humidity 60%, temperature 4 ℃, wind speed 6 m/s) simultaneously with aforementioned interventions, once daily for 2 h each time, for 14 consecutive days. Mice in the control group underwent sham surgery, involving only the incision of the skin and subcutaneous tissue at the knee joint to expose the articular cavity, followed by layer-by-layer suturing. Mice in the treadmill plus climate chamber group were placed on an animal treadmill starting on the 4th day after the sham operation, undergoing high-intensity treadmill exercise at a speed of 20 m/min, an inclination of 5°, for 30min per session, 5 times per week for 28 consecutive days, while being housed in the artificial climate chamber. Cold pain thresholds of the mice in each group were compared using the cold plate test and the acetone low-temperature test before and after modeling. Following modeling, knee joint pathological changes were observed using HE and Safranin O-Fast Green staining, and quantified using Mankin and Osteoarthritis Research Society International (OARSI) scores. Serum levels of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) were measured by ELISA. Protein and mRNA expression levels of pain-related markers, including calcitonin gene-related peptide (CGRP), protein gene product 9.5 (PGP9.5), and cellular proto-oncogene Fos (c-Fos), and the cold hyperalgesia-related markers including transient receptor potential ankyrin 1 (TRPA1) and transient receptor potential melastatin 8 (TRPM8) in the dorsal root ganglion (DRG) tissues were detected by Western Blot and qPCR. TRPA1 and TRPM8 fluorescent intensity in the DRG was detected by immunofluorescence assay. ResultsCompared to the control group, the remaining groups showed decreased cold pain thresholds in the cold plate tese, increased cold pain thresholds in the acetone low-temperature test, elevated Mankin and OARSI scores, and increased serum TNF-α and IL-1β levels, upregulated protein and mRNA expression levels of CGRP, PGP9.5, c-Fos, TRPA1, and TRPM8 in the DRG, and increased immunofluorescence intensities of TRPA1 and TRPM8 in the DRG tissue (P<0.05 or P<0.01), along with severe pathological damage and cartilage degeneration in the knee joints. Compared to the ACLT, DMM, and intra-articular injection groups, the ACLT plus climate chamber, DMM plus climate chamber, and intra-articular injection plus climate chamber groups exhibited more significant changes in all the aforementioned indicators (P<0.01). Furthermore, changes in the aforementioned indicators were more pronounced in the ACLT plus climate chamber group compared to the Treadmill plus climate chamber group, DMM plus climate chamber and intra-articular injection plus climate chamber group (P<0.01), exhibiting the most severe degree of pathological damage and cartilage degeneration. ConclusionThe combination of an artificial climate chamber can successfully establish a disease-syndrome combined animal model of KOA with cold-damp obstruction syndrome, with the ACLT combined with the artificial climate chamber being the optimal modeling approach.
3.Establishment and Evaluation of Different Disease-Syndrome Combination Mice Models of Knee Osteoarthritis with Cold-Dampness Stagnation Syndrome
Enrui HU ; Yibao WEI ; Deren LIU ; Aobuliaisan MAIMAITITUXUN ; Licheng ZHANG ; Jiachen SONG ; Jun MAO ; Taiyang LIAO ; Peimin WANG
Journal of Traditional Chinese Medicine 2026;67(19):2120-2129
ObjectiveTo establish and evaluate different disease-syndrome combination mice models of knee osteoarthritis (KOA) with cold-dampness obstruction syndrome, and to identify the optimal modeling method. MethodsEighty mice were randomly divided into a control group, a treadmill plus climate chamber group, an anterior cruciate ligament transection (ACLT) plus climate chamber group, an ACLT group, a destabilization of the medial meniscus (DMM) plus climate chamber group, a DMM group, an intra-articular injection plus climate chamber group, and an intra-articular injection group, with 10 mice in each group. Mice in the ACLT group underwent surgical transection of the knee anterior cruciate ligament to establish the model, while those in the DMM underwent surgical transection of the medial meniscal tibial ligament of the knee, and those in the intra-articular injection group were modeled by an intra-articular injection of 50 μl of normal saline containing 1mg of monosodium iodoacetate (MIA) into the medial side of the patellar ligament. Mice in the ACLT plus climate chamber, DMM plus climate chamber, and intra-articular injection plus climate chamber groups were placed in an artificial climate chamber (relative humidity 60%, temperature 4 ℃, wind speed 6 m/s) simultaneously with aforementioned interventions, once daily for 2 h each time, for 14 consecutive days. Mice in the control group underwent sham surgery, involving only the incision of the skin and subcutaneous tissue at the knee joint to expose the articular cavity, followed by layer-by-layer suturing. Mice in the treadmill plus climate chamber group were placed on an animal treadmill starting on the 4th day after the sham operation, undergoing high-intensity treadmill exercise at a speed of 20 m/min, an inclination of 5°, for 30min per session, 5 times per week for 28 consecutive days, while being housed in the artificial climate chamber. Cold pain thresholds of the mice in each group were compared using the cold plate test and the acetone low-temperature test before and after modeling. Following modeling, knee joint pathological changes were observed using HE and Safranin O-Fast Green staining, and quantified using Mankin and Osteoarthritis Research Society International (OARSI) scores. Serum levels of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) were measured by ELISA. Protein and mRNA expression levels of pain-related markers, including calcitonin gene-related peptide (CGRP), protein gene product 9.5 (PGP9.5), and cellular proto-oncogene Fos (c-Fos), and the cold hyperalgesia-related markers including transient receptor potential ankyrin 1 (TRPA1) and transient receptor potential melastatin 8 (TRPM8) in the dorsal root ganglion (DRG) tissues were detected by Western Blot and qPCR. TRPA1 and TRPM8 fluorescent intensity in the DRG was detected by immunofluorescence assay. ResultsCompared to the control group, the remaining groups showed decreased cold pain thresholds in the cold plate tese, increased cold pain thresholds in the acetone low-temperature test, elevated Mankin and OARSI scores, and increased serum TNF-α and IL-1β levels, upregulated protein and mRNA expression levels of CGRP, PGP9.5, c-Fos, TRPA1, and TRPM8 in the DRG, and increased immunofluorescence intensities of TRPA1 and TRPM8 in the DRG tissue (P<0.05 or P<0.01), along with severe pathological damage and cartilage degeneration in the knee joints. Compared to the ACLT, DMM, and intra-articular injection groups, the ACLT plus climate chamber, DMM plus climate chamber, and intra-articular injection plus climate chamber groups exhibited more significant changes in all the aforementioned indicators (P<0.01). Furthermore, changes in the aforementioned indicators were more pronounced in the ACLT plus climate chamber group compared to the Treadmill plus climate chamber group, DMM plus climate chamber and intra-articular injection plus climate chamber group (P<0.01), exhibiting the most severe degree of pathological damage and cartilage degeneration. ConclusionThe combination of an artificial climate chamber can successfully establish a disease-syndrome combined animal model of KOA with cold-damp obstruction syndrome, with the ACLT combined with the artificial climate chamber being the optimal modeling approach.
4.Preliminary study of the dose characterization of the INTRABEAM system
Yujie TANG ; Chuanfeng LIU ; Guanbo WANG ; Dehong LI ; Yibao LIU ; Tiantian DAI ; Huagui WANG ; Xiaole ZHANG ; Jianbo CHENG ; Jianwei HUANG ; Xuan ZHANG ; Taiwei SHI
Chinese Journal of Radiological Medicine and Protection 2025;45(5):472-477
Objective:To investigate the dose characteristics of the Zeiss INTRABEAM system in air and water, providing dose reference for electronic brachytherapy.Methods:A Monte Carlo program was used to establish a three-dimensional model of a miniature X-ray source vacuum drift tube and a 4 cm spherical applicator. The process of electron beam bombardment on a gold target to generate X-rays was simulated, and parameters such as photon fluence spectrum, percentage depth dose, and half-value layer were calculated. Additionally, the radial dose uniformity in water was measured.Results:The average energy of X-rays at 3 cm in air was 20.8 keV, with a half-value layer of 0.08 mm Al. Under the influence of the applicator, the spectrum becomes hardened, with axial and radial average energies of 28.7 and 29.0 keV, respectively. In water, the percentage depth dose (PDD) curve follows an inverse cubic decay with depth, indicating strong dose concentration and rapid fall-off in near-field irradiation. The radial dose uniformity in water exceeded 99.5%.Conclusions:The INTRABEAM device emits low-energy X-rays characterized by shallow penetration depth, and concentrated dose delivery. Its highly uniform dose distribution ensures comprehensive coverage of the target area, making it particularly suitable for treating superficial tumors and for intraoperative radiotherapy at close range.
5.Study on the radical kinetics driven by the beam time profile under different oxygen contents in FLASH radiotherapy
Jianhan SUN ; Xianghui KONG ; Jianfeng LYU ; Jinghui WANG ; Xiaodong LIU ; Chen LIN ; Tian LI ; Yibao ZHANG ; Senlin HUANG
Chinese Journal of Radiological Medicine and Protection 2025;45(11):1061-1068
Objective:To reveal the coupling mechanism of beam temporal profile and tissue oxygen content on radical kinetics, further explain the potential biological basis of the FLASH effect, and provide a reference for beam optimization and treatment planning design of FLASH radiotherapy (FLASH-RT).Methods:TOPAS-nBio v3.0 was used to simulate the physical and chemical processes of electron beams in water, and a full-scale kinetic model was established covering the generation, diffusion, reaction, and quenching of free radicals such as hydroxyl radical (·OH) and hydrated electrons (e aq-). Under different beam temporal profiles (single pulse, multi-pulses, continuous wave irradiation) and different oxygen concentration conditions, the evolution dynamics of free radicals were systematically simulated. At the same time, the data on e aq- content were obtained by experimental measurement of laser absorption spectroscopy to verify the accuracy of the model prediction. Results:The changing trend of e aq- concentration measured in the experiment was highly consistent with the simulation result, verifying the reliability of the constructed model. The beam time structure had a significant impact on the peak value and duration of free radical concentration. The single-pulse structure can cause the free radicals to rapidly increase and then quickly quench in a short time, while the continuous or long-pulse structure can cause the radical concentration to remain at a high level for a long time. The evolution of ·OH was not sensitive to the oxygen environment, while e aq- are greatly affected by the oxygen environment. The scavenging efficiency of free radicals in a hypoxic environment was significantly decreased, leading to an enhanced accumulation of oxidative damage to biological macromolecules. The lifespan of e aq- in an oxygen-rich environment decreased rapidly. Conclusions:Radical kinetics are regulated by both the beam temporal profile and oxygen content. FLASH-RT can utilize single-pulse or multi-pulses intervals to form periodic windows, reducing normal tissue damage by efficiently scavenging free radicals through antioxidants, while free radicals in tumor tissues continuously accumulate and amplify damage, thus generating a selective protective effect.
6.Oncology nurse specialist involved in the management of cutaneous immune-related adverse events: a scoping review
Wansheng LI ; Li LI ; Shuping GUO ; Junmei JIA ; Xiaoya HOU ; Na HAN ; Yibao WANG
Chinese Journal of Practical Nursing 2025;41(25):1992-2001
Objective:To conduct a scoping review of the role responsibilities and competencies of oncology nurse specialist in the management of cutaneous immune-related adverse events (cirAEs), with a view to providing scientific guidance and reference for nursing practice in the field of oncology immunotherapy.Methods:Using the scoping review methodology as the framework, the relevant literatures on oncology nurse specialist in the management of cirAEs in databases including PubMed, Web of Science, CINAHL, Embase, Cochrane Library, China National Knowledge Infrastructure, Wanfang Database, and China Biology Medicine from their inception to September 20, 2024 were systematically searched. Two researchers independently screened the included literature, extracted information, and conducted a summary analysis.Results:A total of 24 articles were included. Based on the summary and categorization of the literature, six categories were identified, including dynamic monitoring and assessment, classification and intervention of cirAEs, precise symptom management, multidisciplinary management, continuity of care, and specialized training, along with 18 related responsibility items.Conclusions:Oncology nurse specialist plays a significant role in the management of cirAEs. In the future, it should draw on the training models and curricula of advanced practice oncology nurses from abroad to optimize oncology nurse specialist training and nursing practices, thereby enhancing the professionalism of nursing services and the quality of patient care.
7.Xibining Ⅱ attenuates cartilage damage in knee osteoarthritis rats by regulating glycolysis through AMPK/PGC1α signaling pathway
Yibao WEI ; Zhenyuan MA ; Deren LIU ; Enrui HU ; Xiaochen LI ; Peimin WANG ; Taiyang LIAO ; Wei MEI
Chinese Journal of Pathophysiology 2025;41(8):1569-1577
AIM:To investigate whether Xibining Ⅱ(XBN Ⅱ)attenuates cartilage damage in rats with knee osteoarthritis(KOA)by modulating glycolysis via the AMP-activated protein kinase(AMPK)/peroxisome proliferator-acti-vated receptor γ coactivator 1α(PGC1α)signaling pathway.METHODS:Thirty-two SD rats were randomly divided into sham group,KOA group,XBN Ⅱ group and metformin(AMPK activator)group,with 8 rats in each group.The rats in KOA group were subjected to the anterior cruciate ligament transection procedure to establish the KOA model.Starting from the 14th day after modeling,the rats in XBN Ⅱ group received a daily dose of XBN Ⅱ via gavage once a day,and those in metformin group were administered metformin via intraperitoneal injection once a day for 4 weeks.Subsequently,the histopathological changes of the cartilage were examined by HE and safranin O-fast green staining with matching Mankin and OARSI scores.The protein levels of phosphorylated AMPK(p-AMPK)and PGC1α in cartilage were quanti-fied through immunohistochemistry.In addition,RT-qPCR and Western blot were conducted to measure the mRNA and protein expression levels of glycolysis-related factors,including glucose transporter 1,hexokinase 2 and lactate dehydroge-nase A,biomarkers related to cartilage synthesis and catabolism,such as collagen type Ⅱ,aggrecan,matrix metallopro-teinase 13 and a disintegrin and metalloproteinase with thrombospondin motifs 5,and AMPK/PGC1α signaling pathway-re-lated indicators.RESULTS:Lactate levels in cartilage and serum were higher in KOA group compared with sham group(P<0.05).Similarly,the cartilage in KOA group exhibited significant surface abrasion and structural damage,with faint-stained matrix and significantly higher Mankin and OARSI scores compared with sham group(P<0.05).Further analysis revealed significant decreases in the mRNA and protein expression levels of factors related to cartilage anabolism and AMPK/PGC1α signaling pathway in KOA group compared with sham group(P<0.05).In contrast,there were marked in-creases in the mRNA and protein expression levels of factors related to cartilage catabolism and glycolysis(P<0.05).No-tably,XBN Ⅱ and metformin treatments significantly improved the cartilage morphology,reduced Mankin and OARSI scores,and reversed the changes in mRNA and protein levels of the aforementioned indexes(P<0.05).CONCLU-SION:Treatment with XBN Ⅱ can alleviate cartilage damage in KOA rats by inhibiting glycolysis,through a mechanism involving activation of the AMPK/PGC1α signaling pathway.
8.Investigation of the Mechanism of Cold Hyperalgesia in KOA Mice Relieved by Shangke Lengtongtie Based on HMGB1/CX-CL12/CXCR4 Signaling Axis
Yibao WEI ; Li ZHANG ; Taiyang LIAO ; Lishi JIE ; Zhenyuan MA ; Peng WU ; Zhengquan HUANG ; Li ZHANG ; Liang DING ; Wei MEI ; Runlin XING ; Songjiang YIN ; Xiaochen LI ; Nongshan ZHANG ; Jun MAO ; Pei-min WANG
Journal of Nanjing University of Traditional Chinese Medicine 2025;41(2):195-202
OBJECTIVE To explore the intervention mechanism of Shangke Lengtongtie on cold hyperalgesia in KOA mice based on the HMGB1/CXCL12/CXCR4 signaling axis.METHODS Monosodium iodoacetate(MIA)was used for the intra-articular injec-tion into the knee joint to establish mice model of knee osteoarthritis(KOA).Peripheral blood monocytes were extracted from mice,cultured,and then reinfused into the tail vein of the mice.Subsequently,in vivo animal imaging was used to observe the recruitment sites of these monocytes.The cold hyperalgesia threshold was measured at various time points in each group of mice.Hematoxylin and eosin(HE)staining was used to evaluate the level of synovial pathological changes.ELISA was employed to detect the expression of in-flammatory factors IL-1β,TNF-α,and pain mediators CGRP and Substance P in mouse serum.Western blot and qPCR methods were used to detect the protein and gene expression of cold hyperalgesia-related indicators such as TRPA1,TRPM8,HMGB1,CXCL12,CXCR4,Collagen Ⅰ,and Netrin-1 in synovial tissue,as well as DCC in dorsal root ganglia(DRG)tissue.RESULTS In vivo ima-ging showed that after the monocytes were reinfused into KOA mice,they were recruited to the knee joint area,with the HMGB1 group exhibiting a greater recruitment of circulating monocytes at the knee joint.Additionally,compared to the control group,the KOA group and HMGB1 group showed inflammatory pathological changes in the synovium,increased expression of serum inflammatory factors and pain mediators,reduced cold hyperalgesia threshold,and upregulated protein and gene expression of cold hyperalgesia-related indica-tors in synovial and DRG tissues.The changes were more significant in the HMGB1 group compared to the KOA group(P<0.05).Af-ter treatment with Shangke Lengtongtie or GL intervention,synovial inflammation was alleviated,serum inflammatory factors and pain mediators decreased,cold hyperalgesia threshold increased,and the upregulation of cold hyperalgesia-related indicator protein and gene expression levels was significantly reversed(P<0.05).CONCLUSION Shangke Lengtongtie exerts a beneficial effect on the mitigation of synovitis and cold hyperalgesia in KOA mice,a therapeutic mechanism that possibly mediated through the inhibition of the HMGB1/CXCL12/CXCR4 signaling axis.
9.Preliminary study of the dose characterization of the INTRABEAM system
Yujie TANG ; Chuanfeng LIU ; Guanbo WANG ; Dehong LI ; Yibao LIU ; Tiantian DAI ; Huagui WANG ; Xiaole ZHANG ; Jianbo CHENG ; Jianwei HUANG ; Xuan ZHANG ; Taiwei SHI
Chinese Journal of Radiological Medicine and Protection 2025;45(5):472-477
Objective:To investigate the dose characteristics of the Zeiss INTRABEAM system in air and water, providing dose reference for electronic brachytherapy.Methods:A Monte Carlo program was used to establish a three-dimensional model of a miniature X-ray source vacuum drift tube and a 4 cm spherical applicator. The process of electron beam bombardment on a gold target to generate X-rays was simulated, and parameters such as photon fluence spectrum, percentage depth dose, and half-value layer were calculated. Additionally, the radial dose uniformity in water was measured.Results:The average energy of X-rays at 3 cm in air was 20.8 keV, with a half-value layer of 0.08 mm Al. Under the influence of the applicator, the spectrum becomes hardened, with axial and radial average energies of 28.7 and 29.0 keV, respectively. In water, the percentage depth dose (PDD) curve follows an inverse cubic decay with depth, indicating strong dose concentration and rapid fall-off in near-field irradiation. The radial dose uniformity in water exceeded 99.5%.Conclusions:The INTRABEAM device emits low-energy X-rays characterized by shallow penetration depth, and concentrated dose delivery. Its highly uniform dose distribution ensures comprehensive coverage of the target area, making it particularly suitable for treating superficial tumors and for intraoperative radiotherapy at close range.
10.Study on the radical kinetics driven by the beam time profile under different oxygen contents in FLASH radiotherapy
Jianhan SUN ; Xianghui KONG ; Jianfeng LYU ; Jinghui WANG ; Xiaodong LIU ; Chen LIN ; Tian LI ; Yibao ZHANG ; Senlin HUANG
Chinese Journal of Radiological Medicine and Protection 2025;45(11):1061-1068
Objective:To reveal the coupling mechanism of beam temporal profile and tissue oxygen content on radical kinetics, further explain the potential biological basis of the FLASH effect, and provide a reference for beam optimization and treatment planning design of FLASH radiotherapy (FLASH-RT).Methods:TOPAS-nBio v3.0 was used to simulate the physical and chemical processes of electron beams in water, and a full-scale kinetic model was established covering the generation, diffusion, reaction, and quenching of free radicals such as hydroxyl radical (·OH) and hydrated electrons (e aq-). Under different beam temporal profiles (single pulse, multi-pulses, continuous wave irradiation) and different oxygen concentration conditions, the evolution dynamics of free radicals were systematically simulated. At the same time, the data on e aq- content were obtained by experimental measurement of laser absorption spectroscopy to verify the accuracy of the model prediction. Results:The changing trend of e aq- concentration measured in the experiment was highly consistent with the simulation result, verifying the reliability of the constructed model. The beam time structure had a significant impact on the peak value and duration of free radical concentration. The single-pulse structure can cause the free radicals to rapidly increase and then quickly quench in a short time, while the continuous or long-pulse structure can cause the radical concentration to remain at a high level for a long time. The evolution of ·OH was not sensitive to the oxygen environment, while e aq- are greatly affected by the oxygen environment. The scavenging efficiency of free radicals in a hypoxic environment was significantly decreased, leading to an enhanced accumulation of oxidative damage to biological macromolecules. The lifespan of e aq- in an oxygen-rich environment decreased rapidly. Conclusions:Radical kinetics are regulated by both the beam temporal profile and oxygen content. FLASH-RT can utilize single-pulse or multi-pulses intervals to form periodic windows, reducing normal tissue damage by efficiently scavenging free radicals through antioxidants, while free radicals in tumor tissues continuously accumulate and amplify damage, thus generating a selective protective effect.

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