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.

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.

Objective:To develop a simplified DNA model tailored for Monte Carlo track structure simulations and investigate the influence of microstructural variations at the scale of several base pairs on the physical simulation of proton-induced biological effects, providing a novel approach to enhance the efficiency of modeling and computational processes in proton radiotherapy simulations.Methods:A circular double-helix DNA molecule consisting of 4 362 base pairs was constructed based on the pBR322 plasmid structure. These molecules were evenly distributed without overlap within a spherical region at the center of a water phantom, representing the cellular nucleus. Integrated into the GPU-based gMicroMC code framework, the model facilitated simulations to calculate proton-induced double-strand break (DSB) yields across three distinct models with twist angles of 20°, 36°, and 72° between adjacent nucleotide pairs. Comparative analyses were conducted to assess differences among these models.Results:Intra-model analyses revealed a consistent decrease in proton-induced DSB yields with increasing initial energy. Under proton irradiation at different energies, the DSB yields for the three models followed the order 72°>36°>20°, with intergroup relative differences exceeding 34.6%. Comparative RBE calculations suggested that models with twist angles between 36° and 72° may better replicate proton-induced damage observed in V79 cells.Conclusions:By strategically simplifying the separation of macroscopic and microscopic levels of DNA structure, adjustments to microstructural parameters can be effectively implemented to refine the model, thereby enhancing the efficiency of modeling and physical simulations. This methodology shows potential as a model for simulating relative biological effectiveness (RBE) in proton therapy planning.

Objective:To develop a simplified DNA model tailored for Monte Carlo track structure simulations and investigate the influence of microstructural variations at the scale of several base pairs on the physical simulation of proton-induced biological effects, providing a novel approach to enhance the efficiency of modeling and computational processes in proton radiotherapy simulations.Methods:A circular double-helix DNA molecule consisting of 4 362 base pairs was constructed based on the pBR322 plasmid structure. These molecules were evenly distributed without overlap within a spherical region at the center of a water phantom, representing the cellular nucleus. Integrated into the GPU-based gMicroMC code framework, the model facilitated simulations to calculate proton-induced double-strand break (DSB) yields across three distinct models with twist angles of 20°, 36°, and 72° between adjacent nucleotide pairs. Comparative analyses were conducted to assess differences among these models.Results:Intra-model analyses revealed a consistent decrease in proton-induced DSB yields with increasing initial energy. Under proton irradiation at different energies, the DSB yields for the three models followed the order 72°>36°>20°, with intergroup relative differences exceeding 34.6%. Comparative RBE calculations suggested that models with twist angles between 36° and 72° may better replicate proton-induced damage observed in V79 cells.Conclusions:By strategically simplifying the separation of macroscopic and microscopic levels of DNA structure, adjustments to microstructural parameters can be effectively implemented to refine the model, thereby enhancing the efficiency of modeling and physical simulations. This methodology shows potential as a model for simulating relative biological effectiveness (RBE) in proton therapy planning.

Objective:To analyze the fail mode of neoadjuvant therapy combined with surgery for locally advanced esophageal squamous cell carcinoma (ESCC) after long-term follow-up.Methods:Clinical data of consecutive 238 patients with locally advanced resectable ESCC who underwent neoadjuvant therapy combined with surgery in Zhejiang Cancer Hospital from September 2012 to October 2019 were retrospectively analyzed. The failure mode in the whole cohort was analyzed after long-term follow-up. The overall survival (OS) and disease free survival (DFS) rates were analyzed by Kaplan-Meier method. Survival differences were determined by log-rank test.Results:The pathological complete response (pCR) rate was 42.0% in 238 patients. After a median follow-up of 46.1 months, tumor progression occurred in 96 patients (40.3%), including 25 patients (10.5%) with local recurrence, 61 patients (25.6%) with distant metastases, and 10 patients (4.2%) with simultaneous local recurrence and distant metastases. The median OS and DFS were 64.7 months and 49.9 months. And the 3-, 5-, and 7-year OS and DFS rates were 70.0%, 52.8%, 36.4% and 63.5%, 42.5%, and 30.0%, respectively. The 3-, 5-, and 7-year locoregional recurrence-free survival rates and distant metastasis-free survival rates were 86.0%, 71.4%, 61.2% and 70.6%, 55.9%, 43.0%. Compared with non-pCR patients, the overall progression rate and distant metastasis rate of pCR patients were lower (26.0% vs. 50.7%, 16.0% vs. 32.6%, both P<0.05). And the 3-, 5-, and 7-year OS (83.0% vs. 60.2%, 69.7% vs. 41.7%, 50.4% vs. 27.7%, all P<0.001) and DFS rates (80.4% vs. 51.4%, 63.9% vs. 31.2%, 45.9% vs. 20.3%, all P<0.001) were significantly better in pCR patients. Conclusions:Distant metastasis is the main failure mode of patients with locally advanced ESCC after neoadjuvant therapy. Patients with postoperative pCR can achieve better long-term survival.

Objective:To analyze the failure patterns and survival after stereotactic body radiotherapy (SBRT) in patients with T 1-2N 0M 0 non-small cell lung carcinoma (NSCLC). Methods:Clinical data of early-stage NSCLC patients who received SBRT at Zhejiang Cancer Hospital from January 2012 to September 2018 were retrospectively analyzed. The primary observed endpoint was the pattern of disease progression, which was divided into intra-field recurrence, regional lymph node recurrence and distant metastasis. Overall survival (OS) and progression-free survival (PFS) were calculated by Kaplan-Meier method. Univariate analysis was conducted by log-rank test, and multivariate analysis was performed by Cox's model.Results:A total of 147 patients with 156 lesions were included. The median follow-up time was 44.0 months (16.5-95.5 months). A total of 57 patients (38.8%) progressed: 14 patients (24.5%) had recurrence with the 1-, 3-, and 5-year local recurrence rates of 2.0%, 10.9%, and 14.3%, respectively; 36 patients (63.2%) had Distant metastasis with the 1-, 3- and 5-year distant metastasis rates of 12.2%, 22.4% and 28.6%, respectively; and 7 patients (12.3%) had recurrence complicated with distant metastasis. The 3-, 5- and 7-year OS rates were 80.5%, 64.2% and 49.9% for all patients, respectively. The median OS was 78.4 months. The 3-, 5- and 7-year PFS rates were 64.8%,49.5% and 41.5%, with a median PFS of 57.9 months (95% CI: 42.3-73.5 months). Univariate and multivariate analyses showed that biologically equivalent dose and age were the factors affecting the efficacy of SBRT (both P<0.05). Conclusion:Distant metastasis is the main failure pattern in patients with T 1-2N 0M 0 NSCLC after SBRT. High-risk population should be selected for further systematic treatment to improve the efficacy.

Adaptation, Psychological ; Adolescent ; COVID-19 ; Child ; China ; Cross-Sectional Studies ; Female ; Humans ; Male ; SARS-CoV-2

Objective:To investigate the status quo of human resources of dentists who deal with periodontal disease in Beijing area through an online survey, which may hopefully provide a preliminary basis for the decision-making of administrative departments and the formulation of periodontal professional development plan.Methods:The dentists who deal with periodontal disease at least half a day per week in Beijing area were investigated. A questionnaire was designed by the chairman of the Periodontology Committee of Beijing Stomatological Association. The questionnaire was sent to and finished by the dentists via "WenJuanXing" online survey software. The contents of the survey included general condition, the property of practice unit, title and position of the dentist, membership of professional society, time and content of periodontal treatment, adoption of new technology and new method of periodontal therapy during the past one year, status of periodontal treatment in the local population and reasons, understanding and influencing factors of periodontal professional development.Results:A total of 1 255 dentists completed the survey, who came from all 16 districts in Beijing, mainly Haidian, Chaoyang, Dongcheng and Xicheng Districts [The total percentage of these four main districts was 70.3% (882/1 255)]. The mean age of the dentists was (36.1±8.3) years. Among the dentists, 71.1% (892/1 255) were females, 88.1% (1 106/1 255) got a Bachelor′s degree or above. It was estimated that 35.4% (444/1 255) of the dentists had received standardized periodontal training ever. The percentage of dentists carrying out new technology in the past one year was as high as 68.1% (855/1 255). There were only 163 periodontal specialists (13.0%) out of the dentists in the survey. Only 15.9% (200/1 255) of the dentists routinely performed periodontal surgery. The majority of the dentists [82.8% (1 039/1 255)] were from the state-owned hospitals. Fifty-four point seven percemt (686/1 255) of the dentists thought that lack of knowledge was the main reason why the general public failed to receive periodontal treatment. As for the biggest bottleneck affecting periodontal professional development, fifty-one point zero percent (640/1 255) of the dentists attributed it to the public neglect.Conclusions:The periodontal practitioners in Beijing are young, highly educated, unevenly distributed in 16 districts and mostly females. State-owned oral health institutions are an important force in periodontal diagnosis and treatment services in Beijing. The number of periodontal specialists need to be improved. Promotion of standardized periodontal surgery and the popularization of healthcare knowledge on periodontal disease should also be the focus in the future.

Objective: To analyze the clinical pathologic characteristics of cases with fluorescence in situ hybridization (FISH) positive of exfoliated urothelial cells, so as to evaluate the clinical utility of FISH in the diagnosis of urothelial carcinoma (UC).Methods: A total of 271 cases of FISH positive in Department of Urology of Peking University First Hospital from Apr.2012 to Sep.2015 were recruited in this study.Retrospective analysis was made on their clinical data.For FISH analysis, labeled probes specific for chromosomes 3, 7, 17, and the p16 (9p21) gene were used to assess chromosomal abnormalities indicative of malignancy.The positive predict values (PPV) of all the techniques were analyzed.Results: Of the 271 patients, 207 cases were UC, 7 cases were non-UC, and 57 cases were benign diseases.The PPV of FISH in detecting UC was 76.4%, while the 95% confidence interval (CI) 71.3% to 81.5%.In the cohort of FISH positive, this value was similar to that of urinary cytology (PPV 86.8%, 95% CI: 78.5%-95.0%).The PPV of FISH was lower than that of cystoscopy and ureteroscopy (PPV 96.1%, 95% CI: 91.7%-100.0%).There were significant differences between this study and the PPV of FISH reported abroad (PPV 53.9%, χ2=33.048, P<0.001).Of all the UC with FISH positive, bladder cancer showed an earlier pathological stage versus renal pelvic carcinoma and ureteral carcinoma, with significance (χ2=5.894, P=0.015, and χ2=13.601, P<0.001, respectively).However, no difference was found in the size, pathological stage and pathological grade of tumors between the urinary cytology positive group and the urinary cytology negative group.The rate of high-grade UC in ureteral carcinoma of FISH positive was 92.3%, much higher than that of ureteral carcinoma reported domestically.Conclusion: The PPV of FISH in detecting UC is higher relatively, with a better clinic value for Chinese patients.The ureteral carcinoma with FISH positive obtains a higher pathological grade, which is of great guiding significance for UC.

Objective:To explore the effect of Angelica Sinensis Volatile Oil on the mi RNA expression profiling in myocardium tissue of the spontaneously hypertensive rats (SHRs),and to clarify the possible mechanism of Angelica Sinensis Volatile Oil.Methods:All the SHRs were divided into Angelica group,model group and captopril group,and other Wistar rats with the same age were selected as control group.The non-invasive systolic blood pressure was detected;after 4 weeks of administration,the changes of miRNA expression profiling in myocardium tissue were measured by Affymetrix miRNA 4.0 Array.KEGG analysis was used to identify the target genes. Results:Compared with control group,the systolic blood pressure of the rats in model group was significantly decreased (P < 0.05)before treatment.4 weeks after administration,compared with model group,the systolic blood pressure of the rats in Angelica group was significantly decreased (P <0.05).Compared with model group, 29 differential miRNAs of rats in Angelica group were found (P < 0.05 ), with 13 up-regulated miRNAs and 16 down-regulated miRNAs.The KEGG analysis results showed that miR-19a,let-7i,and miR-181c were related to insulin signaling pathways; let-7i, miR-181a, and miR-455 were related to VEGF signaling pathways;miR-122,miR-181a, miR-200b, miR-181c, let-7i, and miR-19a were related to apoptosis (P < 0.05 ). Conclusion:Angelica Sinensis Volatile Oil can decrease the blood pressure in SHRs and it can regulate the blood pressure by regulating the miRNA related to insulin signaling pathways and VEGF signaling pathways.