This study investigated international standard systems for radiotherapy, focusing on the comparison of the radiation protection standards for medical linear accelerators adopted in China, the UK, and the USA. Despite some specific differences, the standards for radiotherapy rooms in the three countries generally adhere to the basic principles set by the International Commission on Radiological Protection (ICRP) and the International Atomic Energy Agency (IAEA). Regarding the zoning principle of radiotherapy rooms, the definitions of the controlled areas are similar in China, the UK, and the USA, while the classification of areas beyond the controlled areas differs across the three countries. In terms of measurement conditions, all the three countries require measurements under the maximum output dose of the radiotherapy equipment, with only minor differences in details. For dose limits and compliance criteria for radiation shielding of radiotherapy rooms, China adopts the highest instantaneous dose rate as the control threshold. In contrast, the UK and the USA base their standards on dose limits evaluated over certain time intervals (annual, weekly, and daily), assessing compliance through workload calculation. In terms of method for deducing and calculating effective dose limits, UK standards stipulate that annual personnel exposure should be calculated using instantaneous dose rates. In comparison, the USA provides specific method for calculating dose rates per week and any one hour from instantaneous dose rates. The comparative analysis indicates that China′s method, which is based on the maximum instantaneous dose rates, may lead to increased construction costs of radiotherapy rooms under the same conditions, hindering the application and development of novel radiotherapy technologies. To address these concerns while maintaining radiation safety, it is recommended that China consider introducing method based on average instantaneous dose rates or calculating the annual personnel exposure doses. This will help optimize protection standards and advance radiotherapy technology.

Mesenchymal stem cells (MSCs) are an effective therapeutic strategy to delay aging in dogs, they are prone to aging and have poor genetic stability when cultured for a long time in vitro. Therefore, it is of great significance to explore a method to improve the anti-aging ability of MSCs. Previous studies have shown that sirtuin 6 (SIRT6) plays an important role in anti-aging. This study constructed MSCs with overexpressed SIRT6 gene. Through Giemsa staining and senescence-associated β-galactosidase staining, it was found that SIRT6 significantly enhances the anti-aging capacity of MSCs. Transmission electron microscopy imaging and the detection of oxidative stress-related indicators revealed that SIRT6 improves the anti-aging capacity of MSCs by maintaining mitochondrial homeostasis and reducing oxidative stress levels. Transcriptome sequencing analysis revealed that SIRT6 mainly acted on phosphatidylinositol-3-kinase, mitogen-activated protein kinase and other aging and inflammation related pathways. In the establishment and verification of aging models in mice and dogs, it was found that the spatial memory ability of the model mice was significantly increased after intravenous transplantation of SIRT6 overexpression cells, the organ index was also significantly changed, and the anti-oxidative capacity of the dogs and mice blood was improved. The morphology of the spleens and livers in the SIRT6 overexpression cell treatment group could be effectively restored, and the expression levels of aging and inflammation-related proteins were significantly decreased. This study provides a new idea for the study of SIRT6-mediated anti-aging of MSCs.
Animals ; Dogs ; Mesenchymal Stem Cells/metabolism* ; Sirtuins/genetics* ; Aging/physiology* ; Mice ; Oxidative Stress ; Mesenchymal Stem Cell Transplantation

To explore the protective effect of Angelica sinensis polysaccharide(ASP)on leptospiro-sis induced by pathogenic Leptospira infection,the golden hamster model of leptospirosis was se-lected for the experiment.The Leptospira and Leptospira+ASP groups were intraperitoneally injected with Leptospira interrogans serovar Lai strain 56601(1 × 10 6 per hamster).After infec-tion,the Leptospira+ASP group was injected intraperitoneally with ASP(50 mg/kg)for three consecutive days,while the Leptospira group was injected intraperitoneally with normal saline for three days.The experiment employed methods such as daily observation of the clinical symptoms of golden hamsters,statistics of the survival status of each group of golden hamsters,pathological damage of liver,kidney,and lung,bacterial load in organs,and the expression of inflammatory cy-tokines(IL-1β and TNF-α).The results indicated that ASP could effectively alleviate the clinical symptoms of the infected hamsters,enhance the survival rate,ameliorate the pathological damage of the body,reduce the bacterial load in various organs,and mitigate tissue inflammation.This study demonstrated for the first time that ASP has a protective effect on leptospirosis,providing medication guidance for the clinical treatment of leptospirosis.

This study investigated international standard systems for radiotherapy, focusing on the comparison of the radiation protection standards for medical linear accelerators adopted in China, the UK, and the USA. Despite some specific differences, the standards for radiotherapy rooms in the three countries generally adhere to the basic principles set by the International Commission on Radiological Protection (ICRP) and the International Atomic Energy Agency (IAEA). Regarding the zoning principle of radiotherapy rooms, the definitions of the controlled areas are similar in China, the UK, and the USA, while the classification of areas beyond the controlled areas differs across the three countries. In terms of measurement conditions, all the three countries require measurements under the maximum output dose of the radiotherapy equipment, with only minor differences in details. For dose limits and compliance criteria for radiation shielding of radiotherapy rooms, China adopts the highest instantaneous dose rate as the control threshold. In contrast, the UK and the USA base their standards on dose limits evaluated over certain time intervals (annual, weekly, and daily), assessing compliance through workload calculation. In terms of method for deducing and calculating effective dose limits, UK standards stipulate that annual personnel exposure should be calculated using instantaneous dose rates. In comparison, the USA provides specific method for calculating dose rates per week and any one hour from instantaneous dose rates. The comparative analysis indicates that China′s method, which is based on the maximum instantaneous dose rates, may lead to increased construction costs of radiotherapy rooms under the same conditions, hindering the application and development of novel radiotherapy technologies. To address these concerns while maintaining radiation safety, it is recommended that China consider introducing method based on average instantaneous dose rates or calculating the annual personnel exposure doses. This will help optimize protection standards and advance radiotherapy technology.

To explore the protective effect of Angelica sinensis polysaccharide(ASP)on leptospiro-sis induced by pathogenic Leptospira infection,the golden hamster model of leptospirosis was se-lected for the experiment.The Leptospira and Leptospira+ASP groups were intraperitoneally injected with Leptospira interrogans serovar Lai strain 56601(1 × 10 6 per hamster).After infec-tion,the Leptospira+ASP group was injected intraperitoneally with ASP(50 mg/kg)for three consecutive days,while the Leptospira group was injected intraperitoneally with normal saline for three days.The experiment employed methods such as daily observation of the clinical symptoms of golden hamsters,statistics of the survival status of each group of golden hamsters,pathological damage of liver,kidney,and lung,bacterial load in organs,and the expression of inflammatory cy-tokines(IL-1β and TNF-α).The results indicated that ASP could effectively alleviate the clinical symptoms of the infected hamsters,enhance the survival rate,ameliorate the pathological damage of the body,reduce the bacterial load in various organs,and mitigate tissue inflammation.This study demonstrated for the first time that ASP has a protective effect on leptospirosis,providing medication guidance for the clinical treatment of leptospirosis.

Objective:To introduce the clinical dosimetry commissioning methods and results of the 1.5 T MR-linac.Methods:In May, 2019, an Elekta Unity 1.5 T MR-linac was installed in Cancer Hospital, Chinese Academy of Medical Sciences and dosimetry commissioning was performed with magnetic field compatible measuring instruments. Commissioning items include absolute dose calibration, data acquisition and planning system model verification.Results:Absolute dose calibration in magnetic field should be corrected by magnetic field correction factor. The standard output dose of Unity was 87 cGy. Gamma analysis (3%/2 mm) was performed on the beam collection data and the planning system calculation data. The average pass rate of dose verification of standard field test cases was 96.41%, and the TG119 test case was 98.24%. The IROC end to end test case was 97.5%(7%/4 mm).Conclusions:The planning system model and the beam collection data have good consistency. The dose verification results of the standard field and TG119 test cases meet the general tolerance limit requirements of the AAPM TG218 report, and the verification results of the IROC end-to-end test cases meet the IROC center standards.

Objective:To analyze the characteristics of adverse events of active medical devices in Shandong province, as well as the impact of device use duration on the risk rate of adverse events, for reference in improving the monitoring system of active medical device adverse events in China and the level of hospital medical quality management.Methods:The data came from the adverse event reporting data of active medical devices collected by Shandong Adverse Drug Reaction Monitoring Center from January 2019 to October 2021. The R software was used to analyze the distribution, cause and severity of adverse events, and a linear regression model of adverse event risk rate(Y) and adverse event time point(X) was established.Results:A total of 35 254 adverse events of active devices were included, of which 3 059 were serious injuries. The province/municipality with the largest number of reported adverse events was Shanghai(8 006 cases), and the least was Hainan province(4 cases); The majority of adverse events were reported by hospitals, with 34 056(96.60%). The medical devices reporting a higher number of adverse events were ventilators(688 cases), monitors(4 623 cases), infusion pumps(1 079 cases), syringe infusion pumps(1 995 cases), medical electron accelerators(529 cases)and infant incubators(513 cases). In the linear regression model, the risk rate of adverse events increased with the useduration of the device when 0.00%≤ X<14.14%; the risk rate of adverse events decreased with the increase of service time when 14.14%≤ X<100.00%. Conclusions:The number of adverse events reported in each province is different, and hospitals are the main reporting units.The causes of adverse events of different medical devices indicate different correlation strengths with the product itself. The use duration of medical devices poses a great impact on the risk rate of adverse events.