Objective:To investigate the expression level of methyltransferase-like 3 (METTL3) in nasopharyngeal carcinoma cells CNE2 and CNE-2R, and to evaluate the effect of METTL3 on cell invasion, metastasis and radiosensitivity.Methods:Real-time reverse transcription PCR and Western blot were used to detect the expression levels of METTL3 in normal nasopharyngeal epithelial cells NP69 and nasopharyngeal carcinoma cells CNE2 and nasopharyngeal carcinoma radioresistant cells CNE-2R cells. METTL3 in CNE2 and CNE-2R cells was silenced by lentivirus-mediated RNA interference technology. The metastasis and invasion abilities of the cells were detected by the scratch assay and Transwell assay. Clonogenic assay and CCK-8 assay were employed to detect the proliferation capacity and viability of cells irradiated with different X-ray doses (0, 2, 4, 6 and 8 Gy). Apoptosis was detected by flow cytometry. Methylated RNA immunoprecipitation (Me-RIP) assay was used to detect the difference in m6A modification level of c-Jun in CNE2 and CNE-2R cells after METTL3 silencing. The transcriptional stability of c-Jun in cells after silencing METTL3 was detected by actinomycin D assay. A nude mouse xenograft model was constructed to detect the effect of METTL3 on the radiosensitivity of nasopharyngeal carcinoma in vivo. Results:Compared with NP69 cells, the expression levels of METTL3 mRNA and protein were significantly increased in CNE2 cells, and the expression level was even higher in CNE-2R cells (all P<0.01). Lentivirus-mediated RNA interference technology was used to construct a stable METTL3-silencing CNE2 and CNE-2R cell lines (both P<0.01). Scratch assay and Transwell assay showed that the metastasis and invasion abilities of CNE2 and CNE-2R cells were decreased significantly after METTL3 silencing (all P<0.05). Clonogenic assay showed that silencing METTL3 significantly reduced the number of colonies and survival fraction of CNE2 and CNE-2R cells after irradiation with different doses of X-rays (all P<0.05). CCK-8 assay showed that the proliferation ability of CNE2 and CNE-2R cells was significantly reduced by silencing METTL3 (all P<0.05). After different doses of irradiation, silencing METTL3 significantly reduced the survival fraction of CNE2 and CNE-2R cells (all P<0.05). The apoptotic rate after METTL3 silencing was higher than that in the control group at the irradiation dose of 0 and 8 Gy (all P<0.05). The Me-RIP assay showed that the m6A modification level of c-Jun in CNE2 and CNE-2R cells was significantly reduced after METTL3 silencing (both P<0.01), and the actinomycin D assay showed that transcriptional stability of c-Jun was reduced. Nude mouse xenograft experiment showed that silencing METTL3 inhibited xenograft proliferation and improved its radiosensitivity. Conclusion:METTL3 is highly expressed in nasopharyngeal carcinoma cells, and METTL3 mediates m6A modification of c-Jun to improve the transcriptional stability of c-Jun and promote the expression of c-Jun, thereby promoting the invasion and metastasis of nasopharyngeal carcinoma cells and reducing their radiosensitivity.

Artificial intelligence(AI)has emerged as a cutting-edge technology leading the future and is a key engine for China's development.In the innovation and research of medical devices,AI has provided critical support in the areas of intelligent diagnostic assistance,intelligent therapeutic assis-tance,intelligent monitoring,life support,et al.Ma-chine learning-enabled device software functions(ML-DSFs)have become an essential component of many medical devices.Recently,the United States Food and Drug Administration(FDA)released a draft guidance titled"Marketing Submission Rec-ommendations for a Predetermined Change Con-trol Plan for Artificial Intelligence/Machine Learn-ing(AI/ML)-Enabled Device Software Functions(Draft)."that aimed to provide a forward-looking approach to foster the development of ML medical devices.By supporting iterative updates through modifications,this approach ensures the continu-ous safety and effectiveness of the devices.This guidance represents the latest in regulatory direc-tion and is especially beneficial for enhancing the quality and efficiency of clinical trials for AI prod-ucts.Therefore,we plan to provide a detailed intro-duction and interpretation of the guidance,with the aim of learning from international advanced regulatory concepts and experiences to promote the development of ML-DSFs with more profound international influence.

Artificial intelligence(AI)has emerged as a cutting-edge technology leading the future and is a key engine for China's development.In the innovation and research of medical devices,AI has provided critical support in the areas of intelligent diagnostic assistance,intelligent therapeutic assis-tance,intelligent monitoring,life support,et al.Ma-chine learning-enabled device software functions(ML-DSFs)have become an essential component of many medical devices.Recently,the United States Food and Drug Administration(FDA)released a draft guidance titled"Marketing Submission Rec-ommendations for a Predetermined Change Con-trol Plan for Artificial Intelligence/Machine Learn-ing(AI/ML)-Enabled Device Software Functions(Draft)."that aimed to provide a forward-looking approach to foster the development of ML medical devices.By supporting iterative updates through modifications,this approach ensures the continu-ous safety and effectiveness of the devices.This guidance represents the latest in regulatory direc-tion and is especially beneficial for enhancing the quality and efficiency of clinical trials for AI prod-ucts.Therefore,we plan to provide a detailed intro-duction and interpretation of the guidance,with the aim of learning from international advanced regulatory concepts and experiences to promote the development of ML-DSFs with more profound international influence.

Objective:To investigate the expression level of methyltransferase-like 3 (METTL3) in nasopharyngeal carcinoma cells CNE2 and CNE-2R, and to evaluate the effect of METTL3 on cell invasion, metastasis and radiosensitivity.Methods:Real-time reverse transcription PCR and Western blot were used to detect the expression levels of METTL3 in normal nasopharyngeal epithelial cells NP69 and nasopharyngeal carcinoma cells CNE2 and nasopharyngeal carcinoma radioresistant cells CNE-2R cells. METTL3 in CNE2 and CNE-2R cells was silenced by lentivirus-mediated RNA interference technology. The metastasis and invasion abilities of the cells were detected by the scratch assay and Transwell assay. Clonogenic assay and CCK-8 assay were employed to detect the proliferation capacity and viability of cells irradiated with different X-ray doses (0, 2, 4, 6 and 8 Gy). Apoptosis was detected by flow cytometry. Methylated RNA immunoprecipitation (Me-RIP) assay was used to detect the difference in m6A modification level of c-Jun in CNE2 and CNE-2R cells after METTL3 silencing. The transcriptional stability of c-Jun in cells after silencing METTL3 was detected by actinomycin D assay. A nude mouse xenograft model was constructed to detect the effect of METTL3 on the radiosensitivity of nasopharyngeal carcinoma in vivo. Results:Compared with NP69 cells, the expression levels of METTL3 mRNA and protein were significantly increased in CNE2 cells, and the expression level was even higher in CNE-2R cells (all P<0.01). Lentivirus-mediated RNA interference technology was used to construct a stable METTL3-silencing CNE2 and CNE-2R cell lines (both P<0.01). Scratch assay and Transwell assay showed that the metastasis and invasion abilities of CNE2 and CNE-2R cells were decreased significantly after METTL3 silencing (all P<0.05). Clonogenic assay showed that silencing METTL3 significantly reduced the number of colonies and survival fraction of CNE2 and CNE-2R cells after irradiation with different doses of X-rays (all P<0.05). CCK-8 assay showed that the proliferation ability of CNE2 and CNE-2R cells was significantly reduced by silencing METTL3 (all P<0.05). After different doses of irradiation, silencing METTL3 significantly reduced the survival fraction of CNE2 and CNE-2R cells (all P<0.05). The apoptotic rate after METTL3 silencing was higher than that in the control group at the irradiation dose of 0 and 8 Gy (all P<0.05). The Me-RIP assay showed that the m6A modification level of c-Jun in CNE2 and CNE-2R cells was significantly reduced after METTL3 silencing (both P<0.01), and the actinomycin D assay showed that transcriptional stability of c-Jun was reduced. Nude mouse xenograft experiment showed that silencing METTL3 inhibited xenograft proliferation and improved its radiosensitivity. Conclusion:METTL3 is highly expressed in nasopharyngeal carcinoma cells, and METTL3 mediates m6A modification of c-Jun to improve the transcriptional stability of c-Jun and promote the expression of c-Jun, thereby promoting the invasion and metastasis of nasopharyngeal carcinoma cells and reducing their radiosensitivity.

Objective:To study the trend of menarche age in Han and Mongolian women born from 1951 to 2005 in Mongolian region.Methods:A cross-sectional cluster sampling survey method was adopted, From 2003 to 2019, a retrospective survey was carried out in three banners/counties in Tongliao region on the female population of Han and Mongols nationalities aged 16 to 46 and conducted under standardized survey procedures and quality control standards. The basic data of menarche age of women born between 1951 and 2005 were obtained. The changes and rules were analyzed by taking 1 year, 5 years and 10 years as nodes.Results:Totally 46 and conducted under standardized survey procedures and quality control standards 928 pepole (24 450 Han and 22 478 Mongolian) were recruited, the survey response rate was 96.09% (46 928/48 836). In one-year-period analysis, the menarche age gradually decreased from 1951 to 2005. The mean menarche age of Han and Mongolian women changed from (16.22±0.52) years and (15.86±1.24) years in 1951 to (12.37±1.15) years and (12.33±0.98) years in 2005, respectively. The mean menarche age of Han and Mongolian women decreased 3.85 years and 3.54 years. The trend of the mean menarche age's change showed a significant negative correlation with the years (all P<0.000 1). In five-year-period analysis, the mean menarche age of Han and Mongolian women changed from (15.54±1.45) years and (15.53±1.48) years from 1951 to 1955 to (12.41±0.97) years and (12.47±0.96) years from 2001 to 2005, the mean menarche age decreased 3.13 years (3.41 months ahead of schedule every 5 years on average) and 3.06 years (3.34 months ahead of schedule every 5 years on average) in Han and Mongolian women respectively. In ten-year-period analysis, the mean menarche age of Han and Mongolian women changed from (15.79±0.95) years and (15.53±1.33) years from 1951 to 1960 to (12.41±0.97) years and (12.47±0.96) years from 2001 to 2005, the mean menarche age decreased 3.38 years (6.76 months ahead of schedule every 10 years on average) and 3.06 years (6.12 months ahead of schedule every 10 years on average) in Han and Mongolian women respectively. During the 15 years from 1951 to 1965, 1966 to 1970, 1971 to 1990, and 1991 to 2000, they were concentrated at the ages of 15-16, 14-15, 13-14, and 12-13, respectively. The proportion of women at 11 years, 12 years and 13 years menarche age were 26.79% (457/1 706), 73.27% (1 250/1 706), and 92.85% (1 584/1 706) during 2001—2005 in Han women, while the proportion were 23.25% (653/2 809), 62.01% (1 742/2 809), and 90.14% (2 532/2 809) in Mongolian women. Conclusion:The menarche age decreased in Han and Mongolian women from 1951 to 2005, and the ethnic groups tended to be the same. It is recommended to start adolescent education at the age of 8-9 years and pay attention to the changing pattern of early onset of menarche.

Objective:To study the trend of menarche age in Han and Mongolian women born from 1951 to 2005 in Mongolian region.Methods:A cross-sectional cluster sampling survey method was adopted, From 2003 to 2019, a retrospective survey was carried out in three banners/counties in Tongliao region on the female population of Han and Mongols nationalities aged 16 to 46 and conducted under standardized survey procedures and quality control standards. The basic data of menarche age of women born between 1951 and 2005 were obtained. The changes and rules were analyzed by taking 1 year, 5 years and 10 years as nodes.Results:Totally 46 and conducted under standardized survey procedures and quality control standards 928 pepole (24 450 Han and 22 478 Mongolian) were recruited, the survey response rate was 96.09% (46 928/48 836). In one-year-period analysis, the menarche age gradually decreased from 1951 to 2005. The mean menarche age of Han and Mongolian women changed from (16.22±0.52) years and (15.86±1.24) years in 1951 to (12.37±1.15) years and (12.33±0.98) years in 2005, respectively. The mean menarche age of Han and Mongolian women decreased 3.85 years and 3.54 years. The trend of the mean menarche age's change showed a significant negative correlation with the years (all P<0.000 1). In five-year-period analysis, the mean menarche age of Han and Mongolian women changed from (15.54±1.45) years and (15.53±1.48) years from 1951 to 1955 to (12.41±0.97) years and (12.47±0.96) years from 2001 to 2005, the mean menarche age decreased 3.13 years (3.41 months ahead of schedule every 5 years on average) and 3.06 years (3.34 months ahead of schedule every 5 years on average) in Han and Mongolian women respectively. In ten-year-period analysis, the mean menarche age of Han and Mongolian women changed from (15.79±0.95) years and (15.53±1.33) years from 1951 to 1960 to (12.41±0.97) years and (12.47±0.96) years from 2001 to 2005, the mean menarche age decreased 3.38 years (6.76 months ahead of schedule every 10 years on average) and 3.06 years (6.12 months ahead of schedule every 10 years on average) in Han and Mongolian women respectively. During the 15 years from 1951 to 1965, 1966 to 1970, 1971 to 1990, and 1991 to 2000, they were concentrated at the ages of 15-16, 14-15, 13-14, and 12-13, respectively. The proportion of women at 11 years, 12 years and 13 years menarche age were 26.79% (457/1 706), 73.27% (1 250/1 706), and 92.85% (1 584/1 706) during 2001—2005 in Han women, while the proportion were 23.25% (653/2 809), 62.01% (1 742/2 809), and 90.14% (2 532/2 809) in Mongolian women. Conclusion:The menarche age decreased in Han and Mongolian women from 1951 to 2005, and the ethnic groups tended to be the same. It is recommended to start adolescent education at the age of 8-9 years and pay attention to the changing pattern of early onset of menarche.

Objective To verify the dose delivery accuracy of volumetric-modulated arc therapy plan by log-file analysis of linear accelerator that can be created when a dynamic delivery occurs.Methods Accelerator log file in binary format recorded the accelerator execution plan for each control point corresponding to the gantry angle,multi-leaf collimator leave position,cumulative machine monitor units ( MU).These information were read from the accelerator log file with Matlab7.1,then the original control points in the plan file replaced the corresponding information for the log,which generated a new plan.New plan was exported into the planning system to reculculate the dose.The volume dose histogram (DVH) and dose distribution was contrasted to determine the accuracy of the accelerator plan of implementation between two plans.Results Compared with the original plan,antry angle difference over ± 1° accounted for about 35％ of the entire arc of control points in 4 of 12 arcs and the percentage of the leave error of ±0.5 mm was about 95％.MU error of a single control point was larger,but the cumulative MU for each are was small which was located between-0.09％ to 0.11％ in the selected 12 arcs.Between the targets,the maximum dose,minimum dose,the mean dose differences were from-0.07％ to 0.42％,-0.38％ to 0.40％,0.03％ to 0.08％,respectively.The maximum dose and mean dose differences of organs at risks were located from-1.16％ to 2.51％,-1.21％ to 3.12％,respectively.Conclusions Accelerator log-file analysis to verify the VMAT plan nan be supplyed to the experimental method supplement.

Objective To investigate the different influences of simvastatin on proliferation of rat smooth muscle progenitor cells(SPCs) versus endothelial progenitor cells (EPCs) and identify the compounds that differentially inhibit SPCs and EPCs proliferation for clinical usefulness. Methods Total mononuclear cells (MNCs) were isolated from bone marrow of rats by Fieoll density gradient centrifugation, and then the cells were plated on fibronectin-coated culture dishes. SPCs outgrew from the culture of MNCs in the presence of platelet-derived growth factor-BB and basic fibroblast growth factor, whereas EPCs were obtained in the presence of vascular endothelial growth factor. SPCs were identified as adherent cells positive for α-smooth muscle actin (α-SMA) by indirect immunofluoreseent staining. EPCs were characterized as adherent cells double positive for DiLDL-uptake and lectin binding by direct fluorescent staining. SPCs and EPCs were stimulated by simvastatin (0.01～10.00 μmol/L) or vehicle control for the respective time points (6 h, 12 h, 24 h and 48 h). SPCs and EPCs proliferation were assayed with 3H-TdR incorporation and manual counting respectively. Results Simvastatin obviously inhibited SPCs proliferation. At the concentration of 0. 01 μmol/L for 12 h,simvastatin significantly reduced the number of SPCs by (5.8±3.1)% compared with control group (P<0.05). Simvastatin significantly stimulated EPCs proliferation, which was dose- and time dependent and reached maximum at 1 μmol/L after 24 hours (2.0±0.1 fold increase, P<0.01).Conclusions Simvastatin displays different effects on SPCs (inhibited) and EPCs (promoted)proliferation. Local application of simvastatin may inhibit arterial restenosis and promote reendothelialization of injured vessels.