The Chinese space station will be built around 2020. As a national space laboratory, it will offer unique opportunities for studying the physiological effects of weightlessness and the efficacy of the countermeasures against such effects. In this paper, we described the development of countermeasure systems in the Chinese space program. To emphasize the need of the Chinese space program to implement its own program for developing countermeasures, we reviewed the literature on the negative physiological effects of weightlessness, the challenges of completing missions, the development of countermeasure devices, the establishment of countermeasure programs, and the efficacy of the countermeasure techniques in American and Russian manned spaceflights. In addition, a brief overview was provided on the Chinese research and development on countermeasures to discuss the current status and goals of the development of countermeasures against physiological problems associated with weightlessness.
China ; Humans ; Program Evaluation ; Space Flight ; Weightlessness ; Weightlessness Simulation

BACKGROUND: To develop human space exploration, it is necessary to study the effects of an isolated and confined environment, as well as a microgravity environment, on cerebral circulation. However, no studies on cerebral circulation in an isolated and confined environment have been reported. Therefore, we investigated the effects of a 14-day period of confinement in an isolated environment on dynamic cerebral autoregulation. METHODS: We participated in an isolation and confinement experiment conducted by the Japan Aerospace Exploration Agency in 2016. Eight healthy males were isolated and confined in a facility for 14 days. Data were collected on the days immediately before and after confinement. Arterial blood pressure waveforms were obtained using a finger blood pressure monitor, and cerebral blood flow velocity waveforms in the middle cerebral artery were obtained using transcranial Doppler ultrasonography for 6 min during quiet rest in a supine position. Dynamic cerebral autoregulation was evaluated by transfer function analysis between spontaneous variability of beat-to-beat mean arterial blood pressure and mean cerebral blood flow velocity. RESULTS: Transfer function gain in the low- and high-frequency ranges increased significantly (0.54 ± 0.07 to 0.69 ± 0.09 cm/s/mmHg and 0.80 ± 0.05 to 0.92 ± 0.09 cm/s/mmHg, respectively) after the confinement. CONCLUSION: The increases observed in transfer function gain may be interpreted as indicating less suppressive capability against transmission from arterial blood pressure oscillation to cerebral blood flow velocity fluctuation. These results suggest that confinement in an isolated environment for 14 days may impair dynamic cerebral autoregulation. TRIAL REGISTRATION UMIN000020703 , Registered 2016/01/22.
Adult ; Cerebrovascular Circulation ; physiology ; Confined Spaces ; Homeostasis ; physiology ; Humans ; Male ; Middle Aged ; Space Flight ; Young Adult

Long-term spaceflight affects numerous organ systems in the body, including metabolic dysfunction. Recently, ample evidence has demonstrated that the liver is a vulnerable organ during spaceflight. However, the changes in hepatocyte proliferation and cell cycle control under microgravity remain largely unexplored. In the present study, we first confirmed that the serum levels of aspartate aminotransferase, alanine aminotransferase and alkaline phosphatase, biochemical markers of liver function, were altered in rats under tail suspension (TS) conditions to simulate microgravity, as shown in previous reports. Next, we demonstrated that the cell proliferation activity, determined by Ki67, PCNA and PH3, was significantly decreased at the different TS time points (TS for 14, 28 and 42 days) compared with that in the control group. Consistently, the positive cell cycle regulators Ccna2, Ccnd1, Cdk1, Cdk2 and cyclin D3 were also significantly decreased in the TS groups as shown by quantitative real-time PCR and western blotting analysis. Subsequent analysis revealed that the aberrant hepatocyte proliferation inhibition under simulated microgravity was associated with the upregulation of miR-223 in the liver. We further found that miR-223 inhibited the proliferation of Hepa1-6 cells and identified CDK2 and CUL1 as its direct targets. In addition, the decreased expression of CDK2 and CUL1 was negatively correlated with the level of p27 in vitro and in vivo, which may have been responsible for retarding hepatocyte proliferation. Collectively, these data indicate that upregulation of miR-223 was associated with the inhibition of liver cell growth and reveal the role of miR-223 in rat hepatocyte proliferation disorders and the pathophysiological process under simulated microgravity.
Alanine Transaminase ; Alkaline Phosphatase ; Animals ; Aspartate Aminotransferases ; Biomarkers ; Blotting, Western ; Cell Cycle ; Cell Cycle Checkpoints ; Cell Proliferation ; Cyclin D3 ; Hepatocytes* ; Hindlimb Suspension ; In Vitro Techniques ; Liver* ; Proliferating Cell Nuclear Antigen ; Rats* ; Real-Time Polymerase Chain Reaction ; Space Flight ; Up-Regulation* ; Weightlessness*

Cardiac remodeling is the heart's response to external or internal stimuli. Weightlessness/simulated weightlessness leads to cardiac atrophy and heart function declining. Understanding the mechanism of cardiac atrophy under weightlessness is important to help astronaut recover from unloading-induced cardiovascular changes after spaceflight. Unloading-induced changes of hemodynamics, metabolic demands and neurohumoral regulation contribute to cardiac atrophy and function declining. During this process, Ca(2+)-related signaling, NF-κB signaling, ERK signaling, ubiquitin-proteasome pathway and autophagy are involved in weightlessness-induced cardiac atrophy. This article reviews the underlying mechanism of cardiac atrophy under weightlessness/simulated weightlessness.
Atrophy ; Heart ; Heart Diseases ; Hemodynamics ; Humans ; NF-kappa B ; Space Flight ; Weightlessness ; Weightlessness Simulation

The dry seeds of Cassia obtusifolia were carried by the "ShenZhou 8" satellite and sowed after landing. Based on our pri- or study on SP1, the characteristics of plants growth, physiological index and content of effective components were examined. The results showed that the QC10, QC29 strains matured 5 d earlier compared with control. The plant height, across diameter and ground diameter of QC10, QC29, QC46 strains was superior to the control at whole growth period. The branch number increased ranging from 4 to 11 and the number of pods reached 321, 313,281, respectively, which was dramatically higher than the control (246). The yield of QC10, QC29, QC46 strains increased noticeably from 31.4 to 63.2 g. The 1000-seed-weight of QC10, QC29, QC46 strains was 25.86, 25.88, 24.06 g, while the control was 23.69 g. Compared to the control, the mass fraction of chlorophyll was enhanced 1.098, 1.016, 0.297 mg. There was no significant difference in aurantio-obtusin and chrysophanol content of seeds. Through two years research, three high-yield mutant strains were obtained. This study indicates that spaceflight-induced mutants could provide new germplasm for C. obtusifolia breeding and offers the theoretical basis for further utilization of spaceflight-induced mutation to breed high-quality C. obtusifolia strains.
Cassia ; chemistry ; genetics ; growth & development ; Mutation ; Space Flight

OBJECTIVETo explore the effects of pre-acupuncture and immediate acupuncture on kidney function and oxygen free radical metabolism in rats with simulated weightlessness.

METHODSTwenty male clean-grade Wister rats were randomly divided into a normal control group, a model group, a pre-acupuncture group and an immediate acupuncture group, 5 rats in each one. The rats in the normal control group did not receive any treatment but free activities for 4 weeks. The rats in the rest groups received 4-week tail suspension to establish the model of simulated weightlessness. One week before the tail suspension, the rats in the pre-acupuncture group were treated with electroacupuncture at "Shenshu" (BL 23), "Pishu" (BL 20) and "Sanyinjiao" (SP 6) for 30 min per treatment, once a day for 7 days. The rats in the immediate acupuncture group received tail suspension and acupuncture at the same time; during the tail suspension, the electroacupuncture was applied at "Shenshu" (BL 23), "Pishu" (BL 20) and "Sanyinjiao" (SP 6) for 30 min per treatment, once every other day for 14 days. The colorimetric method was used to measure the content of blood urea nitrogen (BUN) in serum as well as activity of superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX) and content of malonaldehyde (MDA) in renal tissue in each group.

RESULTSCompared with the normal control group, the content of BUN in the model group was increased significantly (P<0.01), the activity of SOD and GSH-PX in nephridial tissue was significantly reduced (both P<0.01), and the content of MDA was increased significantly (P<0.05). Compared with the model group, the content of BUN in the pre-acupuncture group and immediate acupuncture group was significantly reduced (P<0.01, P<0.05), the activity of GSH-PX in the pre-acupuncture group was obviously increased (P<0.05) and the content of MDA in the immediate acupuncture group was increased significantly (P<0.01). Compared with the immediate acupuncture group, the content of MDA in the pre-acupuncture group was lower (P<0.01).

CONCLUSIONThe pre-acupuncture and immediate acupuncture both have the capacity to improve the kidney function and anti-oxygen free radical injury in rats with simulated weightlessness, however, the capacity to increase the protection ability of the kidney and eliminate free radical in the pre-acupuncture group is superior to that in the immediate acupuncture group, which is likely to be related with improving antioxidant ability of kidney.

Acupuncture Points ; Acupuncture Therapy ; Animals ; Antioxidants ; metabolism ; Humans ; Kidney ; metabolism ; Kidney Diseases ; metabolism ; physiopathology ; therapy ; Male ; Malondialdehyde ; metabolism ; Rats ; Rats, Wistar ; Reactive Oxygen Species ; metabolism ; Space Flight ; Superoxide Dismutase ; metabolism ; Weightlessness ; adverse effects

OBJECTIVE: To study the incidence of hearing loss at high frequency and the related influence factors among the flight cadets. METHOD: Using multi-stage sampling method, 312 flight cadets were randomly selected from grade 2011,2012,2013. The level of binaural hearing threshold at 4 kHz, 6 kHz, 8 kHz were measured by hearing-assistant evaluative apparatus. Whether or not have hearing loss was chosen as dependent variable. Territory, smoking, dietary habit, previous history of tinnitus, the noise exposure time, the vestibular function and the psychological quality were chosen as independent vailables. T test, ANOVA and accumulative logistic regression were performed to analyze the factors influence on hearing impairment by software SPSS 18.0. RESULT: The morbidity of hearing impairment among flight cadets was 18.9%. Results from single factor analysis showed that the levels of hearing thresholds at 4 kHz, 6 kHz frequency had statistically significant differences between smoking group and non-smoking group (P < 0.05). The levels of hearing thresholds at 4 kHz frequency had statistically significant differences between spicy diet group and not spicy diet group (P < 0.05). The levels of hearing thresholds at 4 kHz, 6 kHz, 8 kHz frequency had statistically significant differences among different strong noise exposure groups (P < 0.05), and that at a same frequency hearing loss increased when noise exposing increased. The levels of hearing thresholds at 4 kHz, 6 kHz frequency had statistically significant difference among different vestibular function groups (P < 0.05). Results of accumulative logistics regression showed that smoking and strong noise exposure were risk factors causing hearing impairment at 4 kHz frequency, and excellent vestibular function seemed to be a preventive factor. Smoking and strong noise exposure were also risk factors causing hearing impairment at 6 kHz frequency. CONCLUSION Hearing impairment appears higher morbidity among flight cadets, and it has statistical correlation with smoking, strong noise exposure and vestibular function.
Hearing Loss ; epidemiology ; Humans ; Logistic Models ; Male ; Risk Factors ; Space Flight ; Young Adult

One of the most important and urgent issues in the field of space medicine is to reveal the potential mechanism underlying the disused muscle atrophy during the weightlessness or microgravity environment. It will conduce to find out effective methods for the prevention and treatment of muscle atrophy during a long-term space flight. Increasing data show that muscle spindle discharges are significantly altered following the hindlimb unloading, suggesting a vital role in the progress of muscle atrophy. In the last decades, we have made a series of studies on changes in the morphological structure and function of muscle spindle following simulated weightlessness. This review will discuss our main results and related researches for understanding of muscle spindle activities during microgravity environment, which may provide a theoretic basis for effective prevention and treatment of muscle atrophy induced by weightlessness.
Animals ; Hindlimb Suspension ; Muscle Spindles ; physiopathology ; Muscle, Skeletal ; physiopathology ; Muscular Atrophy ; physiopathology ; Space Flight ; Weightlessness Simulation

Exposure to thermal environment is one of the main concerns for manned space exploration. By focusing on the works performed on thermoregulation at microgravity or simulated microgravity, we endeavored to review the investigation on space thermal environmental physiology. First of all, the application of medical requirements for the crew module design from normal thermal comfort to accidental thermal emergencies in a space craft will be addressed. Then, alterations in the autonomic and behavioral temperature regulation caused by the effect of weightlessness both in space flight and its simulation on the ground are also discussed. Furthermore, countermeasures like exercise training, simulated natural ventilation, encouraged drink, etc., in the protection of thermoregulation during space flight is presented. Finally, the challenge of space thermal environment physiology faced in the future is figured out.
Aerospace Medicine ; Body Temperature Regulation ; Environment ; Exercise ; Humans ; Space Flight ; Weightlessness ; Weightlessness Simulation

Recent reports show that over 2 billion people are travelling via air every year, and the number of countries involved in space exploration is growing. Aerospace medicine, one of the specialty areas in preventive medicine, focuses on the clinical care, research, and operational support of the health, safety, and performance of crewmembers and passengers of air and space vehicles. Flight surgeons are military medical officers who play an important role in these tasks. The civilian equivalent of the flight surgeon is the aviation medical examiner (AME). Among the challenges that we encounter at high altitudes are a change in pressure, noise, spa-tial disorientation, and acceleration. We should also overcome microgravity and radiation in space. The common in-flight medical emergencies are abdominal pain, diarrhea, chest pain, coll-apse, asthma, diabetes, and allergic reactions. There is only one aerospace medical institute, the Aerospace Medical Center, in the Republic of Korea. The Aerospace Medical Association of Korea, established in 1989, continues to grow. In the near future, aerospace medicine will be an important part of preventive medicine in the Republic of Korea.
Abdominal Pain ; Acceleration ; Aerospace Medicine ; Altitude ; Asthma ; Aviation ; Chest Pain ; Coroners and Medical Examiners ; Diarrhea ; Emergencies ; Humans ; Hypersensitivity ; Korea ; Military Personnel ; Noise ; Preventive Medicine ; Republic of Korea ; Space Flight ; Weightlessness