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.

Background Bacteria are the most diverse and widely sourced microorganisms in the indoor air of subway stations, where pathogenic bacteria can spread through the air, leading to increased health risks. Objective To understand the status and distribution characteristics of indoor air bacterial pollution in subway stations and compartments in a city of Central South China, and to provide a scientific basis for formulating intervention measures to address indoor air bacteria pollution in subways. Methods Three subway stations and the compartments of trains parking there in a city in Central South China were selected according to passenger flow for synchronous air sampling and monitoring. Temperature, humidity, wind speed, carbon dioxide (CO₂), fine particulate matter (PM_2.5), and inhalable particulate matter (PM₁₀) were measured by direct reading method. In accordance with the requirements of Examination methods for public places-Part 3: Airborne microorganisms (GB/T 18204.3-2013), air samples were collected at a flow rate of 28.3 L·min⁻¹, and total bacterial count was estimated. Bacterial microbial species were identified with a mass spectrometer and pathogenic bacteria were distinguished from non-pathogenic bacteria according to the Catalogue of pathogenic microorganisms transmitted to human beings issued by National Health Commission. Kruskal-Wallis H test was used to compare the subway hygiene indicators in different regions and time periods, and Bonferroni test was used for pairwise comparison. Spearman correlation test was used to evaluate the correlation between CO₂ concentration and total bacterial count. Results The pass rates were 100.0% for airborne total bacteria count, PM_2.5, and PM₁₀ in the subway stations and train compartments, 94.4% for temperature and wind speed, 98.6% for CO₂, but 0% for humidity. The overall median (P₂₅, P₇₅) total bacteria count was 177 (138,262) CFU·m⁻³. Specifically, the total bacteria count was higher in station halls than in platforms, and higher during morning peak hours than during evening peak hours (P<0.05). A total of 874 strains and 82 species were identified by automatic microbial mass spectrometry. The results of identification were all over 9 points, and the predominant bacteria in the air were Micrococcus luteus (52.2%) and Staphylococcus hominis (9.8%). Three pathogens, Acinetobacter baumannii (0.3%), Corynebacterium striatum (0.1%), and Staphylococcus epidermidis bacilli (2.2%) were detected in 23 samples (2.6%), and the associated locations were mainly distributed in train compartments during evening rush hours. Conclusion The total bacteria count in indoor air varies by monitoring sites of subway stations and time periods, and there is a risk of opportunistic bacterial infection. Attention should be paid to cleaning and disinfection during peak passenger flow hours in all areas.

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.

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.