BACKGROUND:The imbalance between bone resorption and bone formation in microgravity environments leads to significant bone loss in astronauts.Current research indicates that bone loss under microgravity conditions is the result of the combined effects of various cells,tissues,and systems. OBJECTIVE:To review different biological effects of microgravity on various cells,tissues,or systems,and summarize the mechanisms by which microgravity leads to the development of osteoporosis. METHODS:Databases such as PubMed,Web of Science,and the Cochrane Database were searched for relevant literature from 2000 to 2023.The inclusion criteria were all articles related to tissue engineering studies and basic research on osteoporosis caused by microgravity.Ultimately,85 articles were included for review. RESULTS AND CONCLUSION:(1)In microgravity environment,bone marrow mesenchymal stem cells tend to differentiate more into adipocytes rather than osteoblasts,and hematopoietic stem cells in this environment are more inclined to differentiate into osteoclasts,reducing differentiation into the erythroid lineage.At the same time,microgravity inhibits the proliferation and differentiation of osteoblasts,promotes apoptosis of osteoblasts,alters cell morphology,and reduces the mineralization capacity of osteoblasts.Microgravity significantly increases the number and activity of osteoclasts.Microgravity also hinders the differentiation of osteoblasts into osteocytes and promotes the apoptosis of osteocytes.(2)In a microgravity environment,the body experiences changes such as skeletal muscle atrophy,microvascular remodeling,bone microcirculation disorders,and endocrine disruption.These changes lead to mechanical unloading in the bone microenvironment,insufficient blood perfusion,and calcium cycle disorders,which significantly impact the development of osteoporosis.(3)At present,the mechanism by which microgravity causes osteoporosis is relatively complex.A deeper study of these physiological mechanisms is crucial to ensuring the health of astronauts during long-term space missions,and provides a theoretical basis for the prevention and treatment of osteoporosis.

Objective:Based on multi-subject coordination perspective,it aimed to define the stakeholders in the active health management model,analyze the functional positioning and interests of each party,and put forward relevant governance strategies,so as to provide the participating subjects with governance ideas for the subsequent exploration of the implementation path of active health.Methods:Stakeholders are identified,categorized and managed using Delphi expert consultation and Mitchell scoring method.Results:After two rounds of expert consultation,a total of 17 stakeholders were identified and categorized into three types:deterministic,anticipatory,and marginal stakeholders.In addition,taking into account the opinions from the expert interviews,the functional positioning and interests of each party were further identified,and corresponding management strategies were proposed.Conclusion:Active health management should adopt the strategy of"holistic coordination and categorization",adopting different governance strategies according to the priority of the demands of each type of stakeholder,and at the same time establishing a sound mechanism for sharing responsibilities and preventing conflicts of interest,so as to coordinate and balance the interests of all parties.

Objective:To measure the magnetic field correction factor of reference ionization chamber in a 1.5 T magnetic field and to explore the response of the ionization chamber among different angles between magnetic field and ionization chamber axis.Methods:A home-made magnetic compatible one-dimensional water tank was used to measure the response of PTW30013 and IBA FC65-G in 7 MV photon beam of Elekta Unity with and without magnetic field. The ionizing current was collected by PTW UNIDOS Tango electrometer. The effective measurement point of ionization chamber was positioned to the isocenter of MR-linac using electronic portal image device. The influence on water absorbed dose of reference point was obtained by Monte Carlo calculations.Results:The response of ionization chambers in strong magnetic field was related to the angle between chamber axis and magnetic field. The response of ionization chamber was significantly affected in perpendicular magnetic field with a deviation up to 4.54% compared to parallel magnetic field. The deviation between the magnetic field correction factors measured for parallel or reverse-parallel was 0.03%-0.24%. The magnetic field correction factors for PTW30013 and FC65-G measured in parallel magnetic field were 0.9934±0.0077 and 0.9990±0.0076, respectively.Conclusions:This study experimentally verifies that positioning the ionization chamber axis parallel to the magnetic field direction in MR-linac reference dosimetry can minimize the magnetic field impact. The determined magnetic field correction factor and uncertainty in 1.5 T magnetic field can provide necessary data for establishing an MR-linac reference dosimetry protocol.

Objective:Based on multi-subject coordination perspective,it aimed to define the stakeholders in the active health management model,analyze the functional positioning and interests of each party,and put forward relevant governance strategies,so as to provide the participating subjects with governance ideas for the subsequent exploration of the implementation path of active health.Methods:Stakeholders are identified,categorized and managed using Delphi expert consultation and Mitchell scoring method.Results:After two rounds of expert consultation,a total of 17 stakeholders were identified and categorized into three types:deterministic,anticipatory,and marginal stakeholders.In addition,taking into account the opinions from the expert interviews,the functional positioning and interests of each party were further identified,and corresponding management strategies were proposed.Conclusion:Active health management should adopt the strategy of"holistic coordination and categorization",adopting different governance strategies according to the priority of the demands of each type of stakeholder,and at the same time establishing a sound mechanism for sharing responsibilities and preventing conflicts of interest,so as to coordinate and balance the interests of all parties.

Objective:Based on multi-subject coordination perspective,it aimed to define the stakeholders in the active health management model,analyze the functional positioning and interests of each party,and put forward relevant governance strategies,so as to provide the participating subjects with governance ideas for the subsequent exploration of the implementation path of active health.Methods:Stakeholders are identified,categorized and managed using Delphi expert consultation and Mitchell scoring method.Results:After two rounds of expert consultation,a total of 17 stakeholders were identified and categorized into three types:deterministic,anticipatory,and marginal stakeholders.In addition,taking into account the opinions from the expert interviews,the functional positioning and interests of each party were further identified,and corresponding management strategies were proposed.Conclusion:Active health management should adopt the strategy of"holistic coordination and categorization",adopting different governance strategies according to the priority of the demands of each type of stakeholder,and at the same time establishing a sound mechanism for sharing responsibilities and preventing conflicts of interest,so as to coordinate and balance the interests of all parties.

Objective:Based on multi-subject coordination perspective,it aimed to define the stakeholders in the active health management model,analyze the functional positioning and interests of each party,and put forward relevant governance strategies,so as to provide the participating subjects with governance ideas for the subsequent exploration of the implementation path of active health.Methods:Stakeholders are identified,categorized and managed using Delphi expert consultation and Mitchell scoring method.Results:After two rounds of expert consultation,a total of 17 stakeholders were identified and categorized into three types:deterministic,anticipatory,and marginal stakeholders.In addition,taking into account the opinions from the expert interviews,the functional positioning and interests of each party were further identified,and corresponding management strategies were proposed.Conclusion:Active health management should adopt the strategy of"holistic coordination and categorization",adopting different governance strategies according to the priority of the demands of each type of stakeholder,and at the same time establishing a sound mechanism for sharing responsibilities and preventing conflicts of interest,so as to coordinate and balance the interests of all parties.

Objective:Based on multi-subject coordination perspective,it aimed to define the stakeholders in the active health management model,analyze the functional positioning and interests of each party,and put forward relevant governance strategies,so as to provide the participating subjects with governance ideas for the subsequent exploration of the implementation path of active health.Methods:Stakeholders are identified,categorized and managed using Delphi expert consultation and Mitchell scoring method.Results:After two rounds of expert consultation,a total of 17 stakeholders were identified and categorized into three types:deterministic,anticipatory,and marginal stakeholders.In addition,taking into account the opinions from the expert interviews,the functional positioning and interests of each party were further identified,and corresponding management strategies were proposed.Conclusion:Active health management should adopt the strategy of"holistic coordination and categorization",adopting different governance strategies according to the priority of the demands of each type of stakeholder,and at the same time establishing a sound mechanism for sharing responsibilities and preventing conflicts of interest,so as to coordinate and balance the interests of all parties.

Objective:Based on multi-subject coordination perspective,it aimed to define the stakeholders in the active health management model,analyze the functional positioning and interests of each party,and put forward relevant governance strategies,so as to provide the participating subjects with governance ideas for the subsequent exploration of the implementation path of active health.Methods:Stakeholders are identified,categorized and managed using Delphi expert consultation and Mitchell scoring method.Results:After two rounds of expert consultation,a total of 17 stakeholders were identified and categorized into three types:deterministic,anticipatory,and marginal stakeholders.In addition,taking into account the opinions from the expert interviews,the functional positioning and interests of each party were further identified,and corresponding management strategies were proposed.Conclusion:Active health management should adopt the strategy of"holistic coordination and categorization",adopting different governance strategies according to the priority of the demands of each type of stakeholder,and at the same time establishing a sound mechanism for sharing responsibilities and preventing conflicts of interest,so as to coordinate and balance the interests of all parties.

Objective:Based on multi-subject coordination perspective,it aimed to define the stakeholders in the active health management model,analyze the functional positioning and interests of each party,and put forward relevant governance strategies,so as to provide the participating subjects with governance ideas for the subsequent exploration of the implementation path of active health.Methods:Stakeholders are identified,categorized and managed using Delphi expert consultation and Mitchell scoring method.Results:After two rounds of expert consultation,a total of 17 stakeholders were identified and categorized into three types:deterministic,anticipatory,and marginal stakeholders.In addition,taking into account the opinions from the expert interviews,the functional positioning and interests of each party were further identified,and corresponding management strategies were proposed.Conclusion:Active health management should adopt the strategy of"holistic coordination and categorization",adopting different governance strategies according to the priority of the demands of each type of stakeholder,and at the same time establishing a sound mechanism for sharing responsibilities and preventing conflicts of interest,so as to coordinate and balance the interests of all parties.

Objective:Based on multi-subject coordination perspective,it aimed to define the stakeholders in the active health management model,analyze the functional positioning and interests of each party,and put forward relevant governance strategies,so as to provide the participating subjects with governance ideas for the subsequent exploration of the implementation path of active health.Methods:Stakeholders are identified,categorized and managed using Delphi expert consultation and Mitchell scoring method.Results:After two rounds of expert consultation,a total of 17 stakeholders were identified and categorized into three types:deterministic,anticipatory,and marginal stakeholders.In addition,taking into account the opinions from the expert interviews,the functional positioning and interests of each party were further identified,and corresponding management strategies were proposed.Conclusion:Active health management should adopt the strategy of"holistic coordination and categorization",adopting different governance strategies according to the priority of the demands of each type of stakeholder,and at the same time establishing a sound mechanism for sharing responsibilities and preventing conflicts of interest,so as to coordinate and balance the interests of all parties.