1.Effect of Oral Sodium Butyrate on Skeletal Muscle Atrophy via The Gut-muscle Axis in Antibiotic-pretreated CT26 Tumor-bearing Mice and Its Mechanism
Shu-Ling ZHANG ; Jun-Wei WANG ; Shi-Liang HU ; Tu-Tu WANG ; Shun-Chang LI ; Jia FAN ; Jun-Zhi SUN
Progress in Biochemistry and Biophysics 2026;53(3):724-739
ObjectiveTo explore the effect of oral sodium butyrate on skeletal muscle atrophy in CT26 tumor mice through the gut microbiota-skeletal muscle axis and its potential mechanism. MethodsSixty SPF BALB/c male mice aged 8 weeks were randomly divided into a normal control group (NC, n=18) and a ABX-depleted group (ABX, n=42). The ABX mice were pretreated with a quadruple antibiotic cocktail via oral gavage (0.2 ml per administration, once daily, 6 d per week, for 2 weeks), whereas NC received an equal volume of sterile water. The quadruple antibiotic cocktail consisted of metronidazole (1 g/L), vancomycin (0.5 g/L), ampicillin (1 g/L), and gentamicin (1 g/L). Following successful pretreatment, six mice from each group were randomly selected for gut microbiota sequencing analysis and designated as the Abx group and the NC0 group, respectively. Theremaining mice in ABX were subcutaneously inoculated in the dorsum with 0.2 ml of CT26 cell suspension (at a cell density of 1×107/ml). Then these mice were randomly allocated into three subgroups: a control tumor bearing model group (0_NaB, n=12), a tumor-bearing model group receiving low-dose oral sodium butyrate (L_NaB, n=12), a tumor-bearing model group receiving high-dose oral sodium butyrate (H_NaB, n=12). And mice in NC were inoculated at the same site with 0.2 ml of normal saline. The administration dose for L_NaB was 0.3 g/(kg·d), that for H_NaB was 0.5 g/(kg·d), while NC and 0_NaB were given the same volume of normal saline (0.2ml per time, once daily, 6 d per week, for 4 weeks). The general condition of mice was monitored, and forelimb grip strength gastrocnemius muscle mass and its muscle fiber cross-sectional area were measured for each group. The structural changes in gut microbiota were assessed by 16S rRNA sequencing of cecal contents. Pathological alterations in the intestinal wall were examined via HE staining. Serum and gastrocnemius muscle levels of TNF‑α, IL-6, IL-1β, and LPS were quantified using ELISA. The protein expression of ZO-1 and occludin in the small intestine, as well as proteins associated with the TLR4/MyD88/NF-κB signaling pathway in the gastrocnemius muscle, were detected by Western blot analysis. Results(1) The alpha-diversity in Abx was significantly lower than that in NC0 (P<0.01), a significant decrease of the mass and muscle fiber cross-sectional area of the gastrocnemius (P<0.01), with the majority of gut microbiota being effectively depleted. (2) Compared with NC, the subcutaneous tumors of mice in 0_NaB were prominent, a significant increase of the mass and muscle fiber cross-sectional area of the gastrocnemius, accompanied by a significant decrease in body weight at the end of the 3th and 4th week (P<0.05), and a significant weakening of the forelimb grasping strength at the 5th and 6th week (P<0.01). Compared with 0_NaB, the tumor mass of mice in L_NaB and H_NaB showed a significant decreasing trend, and the grip strength of the forelimbs significantly increased at the 5th and 6th week (P<0.05, P<0.01). (3) Compared with 0_NaB, the Shannon and Observed species indices in α diversity of L_NaB and H_NaB were significantly increased (P<0.05). At the genus level, compared with 0_NaB, L_NaB exhibited a significant decrease in the relative abundance of Parasutterella (P< 0.01), while H_NaB showed significant reductions in the relative abundances of both Escherichia-Shigella and Parasutterella (P < 0.01). (4) Compared with 0_NaB, the small intestinal tissue structure in L_NaB and H_NaB was more intact, the infiltration of inflammatory cells was significantly reduced, and the capillaries were slightly dilated. The expression levels of ZO-1 and occludin proteins in L_NaB were significantly increased (P<0.01). (5) The LPS concentration in the gastrocnemius muscle and the protein expression levels of TLR4, MyD88, p-IκBα, and p-NF‑κB p65 in L_NaB and H_NaB were significantly lower than those in 0_NaB (P<0.05). The serum TNF‑α concentration in H_NaB and TNF-α concentration in the gastrocnemius muscle of the L_NaB and H_NaB were significantly lower than those in 0_NaB (P<0.05, P<0.01, P<0.01). ConclusionOral administration of NaB can improve gut microbiota α diversity, adjusting its composition, improving intestinal mucosal barrier function, reducing the LPS-induced pro-inflammatory response, and delaying skeletal muscle atrophy. The underlying mechanism may involve down regulation of TLR4/MyD88/NF-κB signaling in skeletal muscle.
2.Response to Comments on “Pretreatment 68Ga-PSMA-11 PET/CT to Predict the Response to Treatment With Immune Checkpoint Inhibitors Plus Tyrosine Kinase Inhibitors in Patients With Metastatic Renal Cell Carcinoma”
Shao-Hao CHEN ; Xiao-Hui WU ; Qian-Ren-Shun QIU ; Shao-Ming CHEN ; Jie ZANG ; Jun-Ming ZHU ; Cheng-Long ZENG ; Wei-Bing MIAO ; Xue-Yi XUE ; Ning XU
Korean Journal of Radiology 2026;27(2):188-190
3.Early results and indications of Stand-alone oblique lateral interbody fusion in lumbar lesions.
Zhong-You ZENG ; Xing ZHAO ; Wei YU ; Yong-Xing SONG ; Shun-Wu FAN ; Xiang-Qian FANG ; Fei PEI ; Shi-Yang FAN ; Guo-Hao SONG
China Journal of Orthopaedics and Traumatology 2025;38(5):454-464
OBJECTIVE:
To summarize the early clinical results and safety of Stand-alone OLIF application of lumbar lesions, and explored its surgical indications.
METHODS:
Total of 92 cases of lumbar spine lesions treated with Stand-alone OLIF at two medical centers from October 2014 to December 2018 were retrospectively analyzed, including 30 males and 62 females with an average age of (61.20±12.94) years old ranged from 32 to 83 years old. There were 20 cases of lumbar spinal stenosis, 15 cases of lumbar disc degeneration, 11 cases of lumbar degenerative spondylolisthesis, 6 cases of discogenic low back pain, 7 cases of giant lumbar disc herniation, 13 cases of primary lumbar discitis, 6 cases of adjacent vertebral disease after lumbar internal fixation surgery, and 14 cases of degenerative lumbar scoliosis. Pre-operative dual energy X-ray bone density examination 31 cases' T-values ranged from -1 to -2.4, 8 cases' T-values ranged from -2.5 to -3.5, and the rest had normal bone density. The number of fusion segments: 68 cases of single segment, 9 cases of two segment, 12 cases of three segment , and 3 cases of four segment. Fusion site:L1,2 1 case, L2,3 4 cases, L3,4 10 cases, L4,5 53 cases, L2,3-L3,4 3 cases, L3,4-L4,5 6 cases, L1,2L2,3L3,4 1 case, L1,2L3,4L4,5 1 case, L2,3L3,4L4,5 10 cases, L1,2L2,3L3,4L4,5 3 cases. The clinical results and imaging results of this group of cases were observed, as well as the complications.
RESULTS:
The surgical time ranged from 40 to 140 minutes with an average of (60.92±27.40) minutes. The intraoperative bleeding volume was 20 to 720 ml with an average of (68.22±141.60) ml. The patients had a follow-up period of 6 to 84 months with an average of (38.50±12.75) months. The height of the intervertebral space recovered from (9.23±1.94) mm in preoperative to (12.68±2.01) mm in postoperative, and (9.11±1.72) mm at the last follow-up, there was a statistically significant difference(F=6.641, P=0.008);there was also a statistically significant difference between the postoperative and preoperative height of the intervertebral space(t=9.27, P<0.000 1);and there was also a statistically significant difference (t=10.06, P<0.000 1) between the last follow-up and postoperative height of the intervertebral space. At the last follow-up, cage subsidence grading was as follows:level 0 in 69 cases (76 segments), levelⅠin 17 cases (43 segments), level Ⅱin 5 cases (14 segments), and level Ⅲ in 1 case (1 segment);according to the number of segments, normal subsidence accounts for 56.72%, abnormal subsidence accounts for 43.28%. Bone mineral desity of normal subsidence groups was -0.50±0.07 whinch was better than that the abnormal subsidence groups -2.10±0.43, and the difference was statistically significant(χ2=2.275, P=0.014). As well as there was a statistically significant difference in the patient's VAS of backache from (6.28±2.11) in preoperative to (1.48±0.59) in last follow-up(t=8.56, P<0.05). The ODI recovered from (36.30±7.52)% before surgery to (10.20±2.50)% at the last follow-up, with a statistically significant difference (t=7.79, P<0.000 1). Complications involved 4 cases of intraoperative vascular injury, 21 cases of endplate injury, and 4 cases of combined vertebral fractures. The incision skin has no necrosis or infection. There were 4 cases of left sympathetic chain injury, 4 cases of transient left hip flexion weakness, 2 cases of left thigh anterolateral numbness with quadriceps femoris weakness, and 1 case of incomplete intestinal obstruction;8 cases were treated with posterior pedicle screw fixation due to fusion cage settlement accompanied by stubborn lower back pain, and 6 cases were treated with fusion cage settlement and lateral displacement. According to the actual number of cases, there were 38 complications, with an incidence rate of 41.3%.
CONCLUSION
The application of Stand alone OLIF in lumbar spine disease fusion has achieved good early results, with obvious clinical advantages, but also there are high probability of complications. It is recommended to choose carefully. It is necessary to continuously summarize and gradually clarify and complete the surgical indications and specific case selection criteria.
Humans
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Male
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Female
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Middle Aged
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Spinal Fusion/methods*
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Lumbar Vertebrae/injuries*
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Aged
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Adult
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Retrospective Studies
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Aged, 80 and over
4.Application progress on functional insoles in the prevention and treatment of diabetic foot.
Heng-Yu LIU ; Zhen-de JIANG ; Yao-Kuan RUAN ; Qiu-Ju LI ; Si-Yuan CHEN ; Shun-Yu WEI ; Nan MEI ; Chou WU ; Fei CHANG
China Journal of Orthopaedics and Traumatology 2025;38(9):969-975
Diabetic foot (DF) is one of the most serious chronic complications of diabetes. The incidence rate among global diabetes patients is as high as 15% to 25%, and about 50% of patients will develop contralateral foot ulcers within 5 years after the first unilateral ulcer. As a non-invasive prevention and control solution, the application progress of functional insoles is mainly reflected in the following aspects:(1) Material innovation. The application of new composite materials and smart materials has significantly enhanced the pressure reduction effect and comfort. (2) Structural optimization. The development of multi-layer design and local pressure reduction structure has achieved more precise pressure distribution regulation. (3) Manufacturing process. 3D printing and parametric design have enabled the personalized customization of functional insoles. (4) Intelligent monitoring. It integrates functions such as pressure sensing and temperature monitoring, achieving real-time monitoring and early warning of foot conditions. Clinical research has confirmed that personalized functional insoles could reduce the incidence of foot ulcers and shorten the healing time of ulcers. At present, the research hotspots mainly focus on the development of smart materials, the construction of multi-functional integration and remote monitoring systems. However, in-depth research is still needed in the aspects of biomechanical mechanisms, standardized evaluation systems and long-term efficacy assessment. The development of future functional insoles should focus on the coordinated advancement of "personalization-intelligence-standardization", with the aim of providing more effective solutions for the prevention and treatment of DF.
Humans
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Diabetic Foot/therapy*
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Foot Orthoses
5.Association of higher serum follicle-stimulating hormone levels with successful microdissection testicular sperm extraction outcomes in nonobstructive azoospermic men with reduced testicular volumes.
Ming-Zhe SONG ; Li-Jun YE ; Wei-Qiang XIAO ; Wen-Si HUANG ; Wu-Biao WEN ; Shun DAI ; Li-Yun LAI ; Yue-Qin PENG ; Tong-Hua WU ; Qing SUN ; Yong ZENG ; Jing CAI
Asian Journal of Andrology 2025;27(3):440-446
To investigate the impact of preoperative serum follicle-stimulating hormone (FSH) levels on the probability of testicular sperm retrieval, we conducted a study of nonobstructive azoospermic (NOA) men with different testicular volumes (TVs) who underwent microdissection testicular sperm extraction (micro-TESE). A total of 177 NOA patients undergoing micro-TESE for the first time from April 2019 to November 2022 in Shenzhen Zhongshan Obstetrics and Gynecology Hospital (formerly Shenzhen Zhongshan Urology Hospital, Shenzhen, China) were retrospectively reviewed. The subjects were divided into four groups based on average TV quartiles. Serum hormone levels in each TV group were compared between positive and negative sperm retrieval subgroups. Overall sperm retrieval rate was 57.6%. FSH levels (median [interquartile range]) were higher in the positive sperm retrieval subgroup compared with the negative outcome subgroup when average TV was <5 ml (first quartile [Q1: TV <3 ml]: 43.32 [17.92] IU l -1 vs 32.95 [18.56] IU l -1 , P = 0.048; second quartile [Q2: 3 ml ≤ TV <5 ml]: 31.31 [15.37] IU l -1 vs 25.59 [18.40] IU l -1 , P = 0.042). Elevated serum FSH levels were associated with successful micro-TESE sperm retrieval in NOA men whose average TVs were <5 ml (adjusted odds ratio [OR]: 1.06 per unit increase; 95% confidence interval [CI]: 1.01-1.11; P = 0.011). In men with TVs ≥5 ml, larger TVs were associated with lower odds of sperm retrieval (adjusted OR: 0.84 per 1 ml increase; 95% CI: 0.71-0.98; P = 0.029). In conclusion, elevated serum FSH levels were associated with positive sperm retrieval in micro-TESE in NOA men with TVs <5 ml. In men with TV ≥5 ml, increases in average TVs were associated with lower odds of sperm retrieval.
Humans
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Male
;
Azoospermia/surgery*
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Sperm Retrieval/statistics & numerical data*
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Adult
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Follicle Stimulating Hormone/blood*
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Retrospective Studies
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Testis/pathology*
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Microdissection
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Organ Size
6.Postdischarge cancer and mortality in patients with coronary artery disease: a retrospective cohort study.
Yi-Hao WANG ; Shao-Ning ZHU ; Ya-Wei ZHAO ; Kai-Xin YAN ; Ming-Zhuang SUN ; Zhi-Jun SUN ; Yun-Dai CHEN ; Shun-Ying HU
Journal of Geriatric Cardiology 2025;22(6):578-586
BACKGROUND:
Our understanding of the correlation between postdischarge cancer and mortality in patients with coronary artery disease (CAD) remains incomplete. The aim of this study was to investigate the relationships between postdischarge cancers and all-cause mortality and cardiovascular mortality in CAD patients.
METHODS:
In this retrospective cohort study, 25% of CAD patients without prior cancer history who underwent coronary artery angiography between January 1, 2011 and December 31, 2015, were randomly enrolled using SPSS 26.0. Patients were monitored for the incidence of postdischarge cancer, which was defined as cancer diagnosed after the index hospitalization, survival status and cause of death. Cox regression analysis was used to explore the association between postdischarge cancer and all-cause mortality and cardiovascular mortality in CAD patients.
RESULTS:
A total of 4085 patients were included in the final analysis. During a median follow-up period of 8 years, 174 patients (4.3%) developed postdischarge cancer, and 343 patients (8.4%) died. A total of 173 patients died from cardiovascular diseases. Postdischarge cancer was associated with increased all-cause mortality risk (HR = 2.653, 95% CI: 1.727-4.076, P < 0.001) and cardiovascular mortality risk (HR = 2.756, 95% CI: 1.470-5.167, P = 0.002). Postdischarge lung cancer (HR = 5.497, 95% CI: 2.922-10.343, P < 0.001) and gastrointestinal cancer (HR = 1.984, 95% CI: 1.049-3.750, P = 0.035) were associated with all-cause mortality in CAD patients. Postdischarge lung cancer was significantly associated with cardiovascular death in CAD patients (HR = 4.979, 95% CI: 2.114-11.728, P < 0.001), and cardiovascular death was not significantly correlated with gastrointestinal cancer or other types of cancer.
CONCLUSIONS
Postdischarge cancer was associated with all-cause mortality and cardiovascular mortality in CAD patients. Compared with other cancers, postdischarge lung cancer had a more significant effect on all-cause mortality and cardiovascular mortality in CAD patients.
7.Research Status and Design Ideas of Placebo Manipulation in Clinical Trial Design of Tuina
Jingui WANG ; Haining ZHANG ; Shun FAN ; Yusheng LI ; Hongyi WANG ; An BAO ; Wei ZHANG ; Huanan LI
Journal of Traditional Chinese Medicine 2025;66(11):1128-1132
The rationale for the design of control groups in tuina clinical trial is the foundation for rigorously validating the effectiveness and safety of this therapy. This article reviewed the current state of the design of tuina placebo in control groups of clinical trials, pointed out the necessity of setting up tuina placebo in clinical trials of tuina, analyzed the challenges in implementing blinding of tuina manipulation, and concluded that tuina placebo is still challenged by the placebo effect, the diversification of tuina manipulation but the lack of standardization, and the difficulty of implementing blinding due to the high level of public awareness of tuina. This article also summarized the design of placebo manipulation in three types of clinical trials, including spinal manipulation, acupressure, and paediatric tuina, and proposed four strategies for designing placebo tuina manipulation-controlling placebo effects, developing operational standards for placebo tuina manipulation, ensuring the rigor of blinding implementation, and applying new technologies to enhance the standardization and blinding capacity of placebo tuina methods. So the article is aimed at improving the methodological quality of tuina clinical trial designs, and promoting the standardization and scientificity of tuina clinical trial design.
8.Evaluating the impact of relative dose intensity on efficacy of trastuzumab deruxtecan for metastatic breast cancer in the real-world clinical setting.
Han Yi LEE ; Vivianne SHIH ; Jack Junjie CHAN ; Shun Zi LIONG ; Ryan Shea Ying Cong TAN ; Jun MA ; Bernard Ji Guang CHUA ; Joshua Zhi Chien TAN ; Chuan Yaw LEE ; Wei Ling TEO ; Su-Ming TAN ; Phyu NITAR ; Yoon Sim YAP ; Mabel WONG ; Rebecca DENT ; Fuh Yong WONG ; Tira J TAN
Annals of the Academy of Medicine, Singapore 2025;54(8):458-466
INTRODUCTION:
Trastuzumab deruxtecan (T-DXd) has revolutionised treatment for metastatic breast cancer (MBC). While effective, its high cost and toxicities, such as fatigue and nausea, pose challenges.
METHOD:
Medical records from the Joint Breast Cancer Registry in Singapore were used to study MBC patients treated with T-DXd (February 2021-June 2024). This study was conducted to address whether reducing dose intensity and density may have an adverse effect on treatment outcomes.
RESULTS:
Eighty-seven MBC patients were treated with T-DXd, with a median age of 59 years. At the time of data cutoff, 32.1% of patients were still receiving T-DXd. Over half (54%) of the patients received treatment with an initial relative dose intensity (RDI) of <;85%. Overall median real-world progression-free survival (rwPFS) was 8.1 months. rwPFS was similar between RDI groups (<85%: 8.7 months, <85%: 8.1 months, P=0.62). However, human epidermal growth receptor 2 (HER2)-positive patients showed significantly better rwPFS outcomes compared to HER2-low patients (8.8 versus 2.5 months, P<0.001). Only 16% with central nervous system (CNS) involvement had CNS progressive disease on treatment. No significant progression-free survival (PFS) differences were found between patients with or without CNS disease, regardless of RDI groups. Five patients (5.7%) developed interstitial lung disease (ILD), with 3 (3.4%) having grade 3 events. Two required high-dose steroids and none were rechallenged after ILD. There were no fatalities.
CONCLUSION
Our study demonstrated that reduced dose intensity and density had no significant impact on rwPFS or treatment-related toxicities. Furthermore, only 5.7% of patients developed ILD. T-Dxd provided good control of CNS disease, with 82% of patients achieving CNS disease control.
Humans
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Female
;
Breast Neoplasms/mortality*
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Middle Aged
;
Trastuzumab/adverse effects*
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Aged
;
Adult
;
Singapore/epidemiology*
;
Antineoplastic Agents, Immunological/adverse effects*
;
Camptothecin/adverse effects*
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Immunoconjugates/adverse effects*
;
Retrospective Studies
;
Progression-Free Survival
;
Receptor, ErbB-2/metabolism*
;
Neoplasm Metastasis
;
Dose-Response Relationship, Drug
;
Treatment Outcome
;
Registries
9.Differences in dose-response effects between ultra-high dose rate and conventional dose rate whole abdominal irradiation on acute radiation-induced intestinal injury in mice
Yufeng SHEN ; Jie ZHOU ; Lintao LI ; Fenghao GENG ; Chenxi YANG ; Xiaohua CHEN ; Shuo WANG ; Wei TANG ; Yongjie LI ; Shun LU
Chinese Journal of Radiological Medicine and Protection 2025;45(11):1077-1084
Objective:To compare the dose-response effects of single-fraction ultra-high dose rate (FLASH) and conventional dose rate (CONV) whole abdominal irradiation (WAI) with X-rays on acute radiation-induced intestinal injury in mice, in order to identify optimal dose parameters and potential mechanisms.Methods:A total of 186 male C57BL/6J mice were randomly assigned to a non-irradiation group ( n=6), FLASH irradiation groups ( n=90), and CONV irradiation groups ( n=90). Acute radiation-induced intestinal injury models were established using single-fraction WAI with 11, 12, 13, 14, and 15 Gy X-rays (200 Gy/s for FLASH and 4 Gy/min for CONV). Changes in body weight, stool characteristics, and disease activity index (DAI) scores were assessed at 9 d post-irradiation. At 7 d post-irradiation at 11, 12, and 13 Gy, the intestines were collected for macroscopic examination and length measurement. The small intestine was selected for HE staining and quantitative analysis of intestinal crypt number and mucosal epithelial thickness. The survival of mice was assessed at 15 d post-WAI across all dose groups. Results:After single-fraction WAI at 11, 12, and 13 Gy, the body weight was higher in the FLASH group than that in the CONV group ( t=10.17, 12.65, 10.16, P<0.05). The DAI scores for the FLASH group were 1.00±1.10, 3.17±0.75, and 2.83±1.17, respectively, which were lower than those of the CONV group (4.33±0.52, 7.00±0.00, 8.60±0.55; t=8.70, 11.71, 14.99, P<0.05). However, after WAI at 14 Gy and 15 Gy, there were no significant differences in body weight and DAI between the FLASH group and the CONV group ( P>0.05). At 7 d after single-fraction WAI at 11, 12, and 13 Gy, mice in the FLASH group exhibited less intestinal congestion, edema, and shortening compared with the CONV group. The difference between the FLASH and CONV groups were statistically significant in small intestine length at 11 and 13 Gy ( t=4.42, 3.78, P<0.05), and in colorectal length at 11 and 12 Gy ( t=3.97, 3.12, P<0.05). Small intestine HE staining revealed superior preservation of intestinal architecture in the FLASH group compared with the CONV group, characterized by longer villi, increased crypt numbers, thicker mucosal epithelium, and enhanced structural integrity. The differences in crypt number and mucosal epithelial thickness were statistically significant ( tcrypt=13.10, 23.80, 11.90; tmucosal=5.75, 2.64, 7.74; P<0.05). At 15 d post-irradiation, the survival rate in the 15 Gy FLASH group was higher than that in the CONV group (50% vs. 10%, χ2=5.39, P<0.05), with a median survival extension of 6 d ( HR=0.340, 95% CI: 0.115 4-0.999 9). No significant survival differences were observed between the FLASH group and the CONV group at 11, 12, 13, and 14 Gy ( P>0.05). Conclusions:FLASH irradiation significantly alleviated acute radiation-induced intestinal injury from medium single-fraction WAI with 11, 12, and 13 Gy X-rays compared with CONV irradiation, and showed potential to improve mouse survival after single-fraction WAI at 15 Gy. This effect is likely associated with the preservation of intestinal crypts and exhibits a dose-dependent relationship.
10.Antibacterial efficacy of diode laser on Enterococcus faecalis in root canal:An in vitro study
STOMATOLOGY 2025;45(2):81-88
Objective To investigate the effects of diode laser on the bactericidal effect of Enterococcus faecalis in root canal,the ex-ternal surface temperature of root canal outer wall and the morphology of dentin tubules under different irradiation modes,power,time and days,and to find the appropriate clinical operation parameters and techniques.Methods The single tube permanent tooth roots with completed root tip development were selected and divided into continuous mode group and chopped mode group according to the ir-radiation method.The two groups were irradiated for 10,20 and 30 s with power of 1.5,2.0 and 3.0 W respectively,and were continu-ously irradiated for 3 d.The temperature of the outer wall of the root canal was measured in each group during the first day of irradia-tion,and the colonies of Enterococcus faecalis were counted after daily irradiation.After 3 days of irradiation,the dentin tubule mor-phology of the inner wall of the root canal was observed under scanning electron microscopy,and the opening rate and opening diameter of the dentin tubule were calculated.Results ①With the increase of power and the extension of time,the bactericidal rate increased;the external surface temperature of root canal wall increased,and the dentin tubules gradually melted from opening;the opening diame-ter gradually shrank,and the opening rate gradually decreased,until they were completely fused and closed.In addition,the above trend was more obvious in the continuous mode group than in the chopped mode group under the same parameter.②There was a preser-vation point of bactericidal rate,and there was no significant difference between 2.0 W-30 s,3.0 W-20 s and 3.0 W-30 s under two modes on the second day of irradiation(P>0.05).③The safe temperature limit of the outer surface of the root canal wall(10 ℃)was reached at 1.5 W-30 s,2.0 W-20 s,3.0 W-10 s under continuous mode and 2.0 W-30 s under chopped mode.Conclusion Diode la-ser continuous irradiation of root canal 1.5 W-30 s or chopped irradiation of 2.0 W-30 s for 2 consecutive days can achieve excellent bactericidal effect and no damage to the root and surrounding tissues,and can play a better role in dentin tubule closure.

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