Temporal Characteristics of the Oropharyngeal and Nasal Microbiota Structure in Crewmembers Stayed 180 Days in the Controlled Ecological Life Support System.

Confined experiments are carried out to simulate the closed environment of space capsule on the ground. The Chinese Controlled Ecological Life Support System (CELSS) is designed including a closed-loop system supporting 4 healthy volunteers surviving for 180 days, and we aim to reveal the temporal characteristics of the oropharyngeal and nasal microbiota structure in crewmembers stayed 180 days in the CELSS, so as to accumulate the information about microbiota balance associated with respiratory health for estimating health risk in future spaceflight. We investigated the distribution of microorganisms and their dynamic characteristics in the nasal cavity and oropharynx of occupants with prolonged confinement. Based on the 16S rDNA v3-v4 regions using Illumina high-throughput sequencing technology, the oropharyngeal and nasal microbiota were monitored at eight time points during confinement. There were significant differences between oropharyngeal and nasal microbiota, and there were also individual differences among the same site of different volunteers. Analysis on the structure of the microbiota showed that, in the phylum taxon, the nasal bacteria mainly belonged to Actinobacteria, Firmicutes, Proteobacteria, Bacteroidetes, etc. In addition to the above phyla, in oropharyngeal bacteria Fusobacterial accounted for a relatively high proportion. In the genus taxon, the nasal and oropharyngeal bacteria were independent. Corynebacterium and Staphylococcus were dominant in nasal cavity, and Corynebacterium, Streptococcus, and Neisseria were dominant in oropharynx. With the extension of the confinement time, the abundance of Staphylococcus in the nasal cavity and Neisseria in the oropharynx increased, and the index Chao fluctuated greatly from 30 to 90 days after the volunteers entered the CELSS. Conclusion: The structure and diversity of the nasal and oropharyngeal microbiota changed in the CELSS, and there was the phenomenon of migration between occupants, suggesting that the microbiota structure and health of the respiratory tract could be affected by living in a closed environment for a long time.

Impact of 60 days of 6° head down bed rest on cardiopulmonary function, and the effects of Taikong Yangxin Prescription as a countermeasure.

OBJECTIVE: To study the changes in cardiopulmonary function induced by mid/long-term simulated microgravity with 6° head down bed rest (HDBR), and the effects of Taikong Yangxin Prescription (, TYP) as a countermeasure. METHODS: Fourteen healthy male volunteers were randomly divided into a control group and a Chinese medicine (CM) group (7 in each group) by a random digital table based on their body weight. Both groups underwent 6° HDBR for 60 days. Subjects in the CM group received daily TYP pills and subjects in the control group received daily placebo pills. Cardiac systolic and pumping functions were measured by echocardiography before HDBR; on days 20, 42, and 57 of HDBR; and on day 3 of recovery after HDBR (R+3). Cardiopulmonary functional reserve and exercise capacity were evaluated before HDBR, on day 29, and on day R+3 by exercise testing. RESULTS: The heart rate (HR) increased gradually during HDBR. The HR was significantly higher on day 57 than before HDBR in the control group (P<0.05), but did not increase significantly in the CM group. The stroke volume/stroke volume index, ejection fraction, and left ventricular fractional shortening tended to decrease over time in the control group, but not in the CM group. These parameters were significantly higher in the CM group than in the control group on day 42 (P<0.05 or <0.01). Exercise testing showed that maximum O2 consumption (VO2max), metabolic equivalents, relative O2 consumption (VO2), O2 pulse, and exercise duration were significantly lower on day 29 than before HDBR in the control group, but not in the CM group. CONCLUSIONS: Sixty days of 6° HDBR induced a reduction in cardiac systolic and pumping functions, and reduced cardiopulmonary functional reserve and exercise capacity. Administration of TYP significantly improved cardiac systolic and pumping functions, and maintained cardiopulmonary functional reserve and exercise capacity.

Acute effects of hyperglycaemia with and without exercise on endothelial function in healthy young men.

Post-prandial hyperglycaemia impairs endothelial function as evaluated by brachial artery flow-mediated dilation (FMD). Exercise is an intervention to protect against cardiovascular disease and to improve FMD. In this study, we examined whether the effect of acute hyperglycaemia on endothelial function in healthy young men is restored by aerobic exercise. Using a counterbalanced, randomized crossover design, we measured the brachial artery FMD at baseline and 1, 2, 3 and 4 h after 75 g glucose ingestion in 11 healthy young men, with and without a single bout of aerobic exercise. Brachial artery FMD declined from 11.4 +/- 3.8% at baseline to 7.3 +/- 3.4% 1 h after oral glucose ingestion, and returned to baseline after 4 h. When the oral glucose ingestion was followed immediately by 45 min of treadmill exercise at an intensity of 60% maximal oxygen uptake, FMD demonstrated no significant decrease (11.8 +/- 2.5, 11.3 +/- 2.8, 12.2 +/- 2.7, 13.5 +/- 3.5, and 12.6 +/- 2.4% at baseline and 4 h after ingestion, respectively). The results indicate that the aerobic exercise restores the impaired FMD induced by oral glucose ingestion.

[Effects of 21 d -6 degrees head down bed-rest on pulmonary gas distribution and little airway function].

OBJECTIVE: To probe the effect of 21 d -6 degrees head down bed-rest (HDBR) on pulmonary gas distribution and little airway function. METHOD: The indices of the pulmonary gas distribution and little airway function (delta N2, CV, CV/VC%, LCI) were measured in 16 healthy male subjects before, during and after 21 d -6 degrees HD-BR. RESULT: Comparing with before and early days of HDBR, recovery supine delta N2 increased significantly. CV increased significantly only on the first day of HDBR, and changes of CV/VC% were same as CV. The changes of LCI were not significant. CONCLUSION: The indices of pulmonary gas distribution were affected by 21 d -6 degrees HDBR. Pulmonary gas distribution was more uneven during and after 21 d -6 degrees HDBR.

[Preventive effects of exercise training on bone loss during 21 d -6 degrees head down bed-rest].

OBJECTIVE: To observe the protective effects of exercise training during 21 d -6 degrees head down bed rest (HDBR) on bone loss. METHOD: Ten healthy young men were randomly divided into HDBR group and HD-BR exercise group, with 5 in each group. Both groups were exposed to -6 degrees head down bed rest for 21 d. The subjects in the exercise group performed exercise with a bicycle ergometer in supine position 1 h/d during bed rest. Femur bone mineral density (BMD), serum bone gla protein (BGP) as well as hydroxyproline/creatinine (HOP/Cr) were determined before and during 20 d HDBR. RESULT: As compared with the before HDBR values, average femur BMD decreased by 5.8% and 0.9% for HDBR group and HDBR and exercise group respectively. HOP/Cr significantly increased in the HDBR group and was significantly higher than the HDBR exercise group. BGP decreased in both groups with no significant difference. CONCLUSION: Exercise during 21 d -6 degrees HDBR is beneficial in preventing bone loss.