Müller cells are activated in response to retinal outer nuclear layer degeneration in rats subjected to simulated weightlessness conditions

A microgravity environment has been shown to cause ocular damage and affect visual acuity,but the underlying mechanisms remain unclear.Therefore,we established an animal model of weightlessness via tail suspension to examine the pathological changes and molecular mechanisms of retinal damage under microgravity.After 4 weeks of tail suspension,there were no notable alterations in retinal function and morphology,while after 8 weeks of tail suspension,significant reductions in retinal function were observed,and the outer nuclear layer was thinner,with abundant apoptotic cells.To investigate the mechanism underlying the degenerative changes that occurred in the outer nuclear layer of the retina,proteomics was used to analyze differentially expressed proteins in rat retinas after 8 weeks of tail suspension.The results showed that the expression levels of fibroblast growth factor 2(also known as basic fibroblast growth factor)and glial fibrillary acidic protein,which are closely related to Müller cell activation,were significantly upregulated.In addition,Müller cell regeneration and Müller cell gliosis were observed after 4 and 8 weeks,respectively,of simulated weightlessness.These findings indicate that Müller cells play an important regulatory role in retinal outer nuclear layer degeneration during weightlessness.

Effect of long-term weightlessness on retina and optic nerve in tail-suspension rats

AIM： To evaluate the effect of long weightlessness on retina and optic nerve in suspension （TS） rats. -term tail METHODS： A stimulated weightlessness model was established by suspending rats tail. After 12wk, the ultrastructure and the number of optic nerve axons were observed by transmission electron microscope. The number of survival retinal ganglion cells （RGCs） was calculated by fluorescent gold retrograde labeling. Retina cells apoptosis was detected by TUNEL staining. The function of optic nerve and retina was evaluated by the visual evoked potential （VEP） and oscillatory potentials （Ops）. RESULTS： The optic nerve axons were swollen and sparsely aligned, and the lamellar separation and myelin disintegration occurred after 12wk in TS rats. The density of optic nerve axons was 32.23±3.92 （ ys 37.43±4.13, P= 0.0145）, the RGCs density was 1645 ±46 cells/mm^2 （vs 1867±54 cells/mm^2 F=0.0000）, the incidence rate of retinal cells apoptosis was 5.38%±0.53% （ vs 4.75%±0.54%, P= 0.0238）, the amplitude of VEP-P100 was 15.43±2.14 μV （vs 17.67±2.17 μV, P=0.0424）, the latency of VEP-P100 was 69.05v5.34ms （vs 62.43±4.87ms P=0.0143） and the sum amplitude of Ops was 81.05±8.34 μV （Ys 91.67± 10.21 μV, P=0.0280） in TS group and the control group, respectively. CONCLUSION： Long-term weightlessness can induce the ultrastructural changes and functional depress of the optic nerve, as well as retinal cell damages in TS rats.

Influences of traditional Chinese medicine intervention on the bone growth and metabolism of rats with simulated weightlessness

Objective:To prohe into the influences of Chinese herbal compound on the growth and metabolism of weight-bearing bones of tail-suspended rats.Methods:Twenty-four male St) rats were randomly divided into blank conlrol group leighti.tail-suspended conlrol group(eight) and Chinese medicine treatment group leighti according to their weights.No treatment was done for the blank conlrol group.Double distilled water lavage was performed daily for the tail-suspended control group.On the basis of the tail-suspended rat model,the rats were given Chinese herbal compound lavage every day in Chinese medicine treatment group.This compound includes mulberry,Poria cocas and barbary wolfberry.etc.The lest cycle was four weeks.The rats were killed after the experiment.The right femoral bone was taken out for the physical measurements, and the left femoral bone was for the three-point beading test.The influences of Chinese herbal compound on femoral hone growth and biomechanicsl properties of simulated weightlessness rats were observed.Results:(1) After simulated weightlessness(tail-suspension),compared with the blank control group,all the physiological indexes of rat femoral bone decreased in tailsuspended group and Chinese medicine treatment group(P【0.05).The strength and rigidity of rat femoral bone decreased in tail-suspended group(P【0.01).the maximum load and rigidity coefficient also decreased with the inereasing toughness coefficient in the control group(P【0.01). i2i After the countermeasure of Chinese herbal compound,each biomcchanical indexes showed the tendency of increasing in Chinese medicine treatment group,and theses indexes were close to those of the blank control group(P【0.05),which indicated that(he bone loss caused by simulated weightlessness was improved.Conclusions:Chinese herbal compound for tonifying kidney could effectively prevent the bone loss and have some enhancements on the bone hiomechanical properties.

Effects of Simulated Weightlessness on Tight Junction Protein Occludin and Zonula Occluden-1 Expression Levels in the Intestinal Mucosa of Rats

This study investigated the tight junction（TJ） protein expression of the intestinal mucosa in a rat tail-suspension model under simulated weightlessness.Twenty-four Wistar rats were randomly divided into three groups：CON group（n=8）,control; SUS-14 d group（n=8）,tail-suspension for 14 days; SUS-21 d group（n=8）,tail-suspension for 21 days.Occludin and Zonula Occluden-1（ZO-1） expression levels were determined by immunohistochemical analysis and mRNA fluorescent quantitative PCR.Plasma levels of diamine oxidase（DAO） and d-lactate were determined using enzymatic spectrophotometry.Immunohistochemical results for occludin and ZO-1 showed disruption of the TJs in the intestinal mucosa in SUS-14 d and SUS-21 d groups.The expression levels of occludin and ZO-1 in SUS-21 d group were lower than those in SUS-14 d group,and significantly lower than those in CON group（Occldin：0.86±0.02 vs 1.01±0.03 vs 1.63±0.03 and ZO-1：0.82±0.01 vs 1.00±0.02 vs 1.55±0.01,P〈0.01）.Moreover,the levels of plasma DAO and d-lactate in SUS-21 d group were higher than those in SUS-14 d group,and significantly higher than those in CON group（DAO：27.58±0.49 vs 20.74±0.49 vs 12.94±0.21 and d-lactate：37.86±0.74 vs 28.26±1.01 vs 17.76±0.91,P〈0.01）.There were significant negative correlations between occludin or ZO-1 expression levels and DAO（r2=0.9014,r2=0.9355,P〈0.01） or d-lactate levels（r2=0.8989,r2=0.9331,P〈0.01）.Occludin and Zo-1 were reduced in intestinal mucosa both in mRNA and protein levels in the rat tail-suspension model.The significant negative correlations between expression levels of TJs and plasma levels of DAO or d-lactate support the hypothesis that intestinal permeability is increased due to a decrease in TJ protein expression during tail-suspension from 14 days to 21 days.

Changes of Stress-Strain Relationship of Rabbit Femoral Vein after Simulated Weightlessness

Objective: To observe the effect of simulated weightlessness on stress-strain relationship and the structural change of rabbit femoral vein. Methods: After seting up the Head-Down Tilt (-20°) (HDT) model to simulate weightlessness, 24 healthy male New-Zealand Rabbits were randomly divided into HDT-21d group, HDT-10d group and control group, with 8 in each. Femoral venous strips and rings were used to make uniaxial tensile test of the longitudinal and circumferential specimens of the vessels. At last we observed the microstructure of femoral vein wall in 3 groups. Results : With the increasing of load stress, both longitudinal and circumferential strains of vein samples from 3 groups increased significantly (P<0. 01). With the decrease of unload stress, strains decrease obviously (P<0. 01). The unloaded longitudinal and the circumferential strain from 3 groups increased much than those of the loaded. Under the same stress (longitudinal 0-2. 0 g, circumferential 0. 5-1. 0 g) , HDT-21d group and HDT-10d group increased obviously in tlie longitudinal or circumferential strain (load and unload) than control, and HDT-21d increased much than that of HDT-10d. The contents and structures of femoral vein walls of HDT-rabbits changed significantly. Some endotheli-um cells of femoral vein became short, columnar or cubic even fell off. Smooth muscle layers became thinner. Conclusion:The compliance of femoral venous increased significantly after weightlessness-simulation and increased much obviously after 21d-HDT than that of 10 d. The structure of femoral vein wall changed obviously. The changes may be one reason for the increase of femoral vein compliance.

EFFECT OF SIMULATED WEIGHTLESSNESS ON REPRODUCTION OF ADULT MALE RATS

Objective To study the effects of simulated weightlessness induced by tail-suspension on reproduction in adult male rats and its mechanisms. Methods Twenty Spraque-Dawley adult male rats were randomly divided into two groups: the experimental group and control group. Rats in the experimental group were tail-suspended for 14 days. After the treatment, the weight and morphology of testis, the quantity and quality of sperm, the level of serum testosterone and the apoptosis rate of testicular cells were observed. Results Compared with the control, the testicular weight, the quantity and quality of sperm, the level of serum testosterone significantly decreased (P<0.05) while the apoptosis rate of testicular cells significantly increased (P<0.05) in tail-suspended rats. In addition, hematoxylin and eosin (HE) staining showed that seminiferous tubules atrophied, spermatogenic cells decreased, seminiferous epithelial cells disintegrated and shed, and the lumina were azoospermic. Conclusion Simulated weightlessness induced by tail-suspension has a harmful effect on male reproduction of adult rats by increasing the apoptosis of testicular cells.

THE MORPHOLOGICAL CHANGES IN MUSCLE SPINDLES AND ALTERATIONS IN CELL ACTIVITY OF THE RATS' RED NUCLEUS AFTER 2 WEEKS' SIMULATED WEIGHTLESSNESS

Objective To study the morphological changes of soleus muscle spindle and electrical activity of neurons in Red Nucleus(RN) of the rat after 2 weeks' simulated weightlessness, and to reveal the interaction between proprioceptive inputs of muscle spindles and reciprocal alterations in RN under simulated weightlessness. Methods Twenty female rats were exposed to weightlessness simulated by tail-suspension for 14 days (SW-14d). Body weight(200-220g) matched female rats were control group(Con). The morphological changes in isolated muscle spindle of soleus muscle, the discharges of red nucleus neurons were observed after 14d tail-suspensions by silver staining and extracellular recording respectively. Results Compared with control group ,the nerve ending of muscle spindle in SW-14d was distorted, degenerated and dissolved; the diameters of intrafusal fibers and capsule in equatorial region of soleus muscle spindles were diminished(P<0.05). The spontaneous cell activity and discharge of RN neurons (spikes/s) induced by afferent firing from muscle spindles after injection of succinylcholine were reduced after 2 weeks' simulated weightlessness respectively (18.44±5.96 vs. 10.19±6.88, 32.50±8.08 vs. 16.86±5.97, P<0.01). Conclusion The degeneration of muscle spindle induced by simulated weightlessness may be one of the causes that led to alterations in discharges of RN.

Fos expression in the medullary visceral zone following transient decrease of blood pressure in rats under simulated weightlessness

Objective: To observe Fos expression after transient decrease of blood pressure in catecholaminergic neurons of the medullary visceral zone(MVZ) in simulated weightlessness rats. Methods: Simulated weightlessness was abtained by tail suspension for 4 weeks, and transient decrease of blood pressure was induced by intravenous injection of sodium nitroprusside. Fos expression in catechlaminergic neurons of MVZ were visualized by an immunohistochemical double-labeling technique with anti-Fos and anti-tyrosine hydroxylase (TH) antibodies. Results: The decrease of blood pressure in the simulated weightlessness rats resulted in Fos expression in many neurons of the medulla oblongata, and they were primarily localized in the MVZ. In the MVZ, Fos-positive neurons were concentrated in the nucleus of the solitary tract (NTS) and ventrolateral region of the medulla (VLM). On the other hand, the numbers of Fos-positive neurons in MVZ were smaller than that of control rats (treated with tail suspension or intravenous injection of sodium nitroprusside only). Although some TH-positive neurons were found to be Fos-positive, the proportion of TH/Fos double-labeled neurons was much lower than that of the control rats; intensity of TH-like immunoreactivity was also reduced. Conclusion: The decrease of Fos-positive neurons and proportion of catechlaminergic neurons expressing Fos protein may result from decrease of parasympathetic activity in the simulated weightlessness rats.

Effects of electrostimulation and administration of succinylcholine on the expression of Fos protein in mesencephalic periaqueductal gray matter of rats after simulated weightlessness

BACKGROUND： Expression of Fos in neurons of periaqueductal gray （PAG） is used to reflect the excitability. However, changes of expression of Fos in neurons of PAG are caused by injured electrostimulation after simulated weightlessness, and the relationship between pretreatment and injection of succinylcholine has not been determined yet. OBJECTIVE ： To investigate the changes of expression of Fos in PAG induced by injured electrostimulation pretreatment and injection of succinylcholine at 2 weeks after simulated weightlessness.DESIGN： Observational and controlled animal study.SETTING： Department of Physiology, Medical School, Xi＇an Jiaotong University; Key Laboratory of Environment and Genes Related to Diseases, Ministry of Education. MATERIALS： A total of 24 adult female SD rats, of clean grade and weighing 180-220 g, were selected in this study. METHODS： The experiment was completed in the Experimental Animal Center of Xi＇an Jiaotong University.① All rats were randomly divided into 2 groups according to body mass： simulated weightlessness group and control group with 12 in each group. And then, each group was also divided into 3 subgroups： electrostimulation group, succinylcholine-pretreatment group and succinylcholine-injection group with 4 in each subgroup. ②The model of weightlessness was simulated by tail-suspended female rats, which were described and modified by Cheng Jie. Rats in normal control group were given the same interventions as simulated weightlessness group except for tail-suspended. ③ Experimental method： The rats in electrostimulation group were given nociceptive stimulus by a pair of subcutaneous electrodes inserted into 1 and 5 claw of left hindlimb. The stimulus （current： 10 mA; duration： 1 ms; interval： 1 s） lasted for 30 minutes. The rats in succinylcholine-pretreatment group received stimulus after intravenous administration of succinylcholine, rats in succinylcholine-injection group were not given stimulus, just received succinylcholine. ④ All rats were perfused and fixed after 2 hours from the end of stimulation. The brains were removed, and serial frozen sections of midbrain were stained using immunocytochemical method, observed and taken photos under light-microscope. The number and morphological characters of Fos-immunoreactive （Fos-IR） neurons in ventrolateral part of PAG were investigated. MAIN OUTCOME MEASURES： The alterations in number and morphological characters of Fos-IR neurons in ventrolateral PAG of all rats.RESULTS： A total of 24 rats were involved in the final analysis. ① The morphological changes of Fos-IR neurons： The expressions of Fos in ventrolateral part of PAG were observed in both control and simulated weightlessness groups rats after being given nociceptive stimulus. As compared with control group, Fos-IR neurons in simulated weightlessness group were dyed lightly, cellular integrity was impaired, and cellular verge was unclear. ② The numbers of Fos-IR neurons： In control group, the numbers of Fos-IR neurons in ventrolateral part of PAG in simulated weightlessness group were obviously lower than succinylcholine-pretreatment group, but obviously higher than succinylcholine-injection group （46.94±3.38, 71.06±8.96 and 35.04±4.62, respectively, P 〈 0.05）. In 14-day simulated weightlessness group, the numbers of Fos-IR neurons in electrostimulation group were also obviously lower than succinylcholine-pretreatment group, and obviously higher than succinylcholine-injection group （27.77±3.27, 32.91±2.99 and 11.75±1.00, respectively, P 〈 0.05）. The numbers of Fos-IR neurons in all subgroups in control group were obviously higher than those subgroups in simulated weightlessness group. Compared with electrostimulation group, the percentage of expression of Fos in ventrolateral part of PAG responsed to nociceptive stimulus after administration of succinylcholine （SCH） was increased to 51.83% in control group and 18.51% in simulated weightlessness group.CONCLUSION ：① The expression of Fos in neurons in ventrolateral part of PAG were increased by the pretreatment of SCH before nociceptive stimulus.② Nociceptive stimulus could increase the expression of Fos in neurons in ventrolateral part of PAG. ③ The numbers of Fos-IR neurons in ventrolateral part of PAG were decreased obviously after 2-week simulated weightlessness.

Role of muscle spindle in weightlessness-induced amyotrophia and muscle pain

To date, the medium and long-term space flight is urgent in need and has become a major task of our manned space flight program. There is no doubt that medium and long-term space flight has serious damaging impact upon human physiological systems. For instance, atrophy of the lower limb anti-gravity muscle can be induced during the space flight. Muscle atrophy significantly affects the flight of astronauts in space. Most importantly, it influences the precise manipulation of the astronauts and their response capacity to emergencies on returning to the atmosphere from space. Muscle atrophy caused by weightlessness may also seriously disrupt the normal life and ＇work of the astronauts during the re-adaptation period. Here we summarize the corresponding research concentrating on weightlessness-induced changes of muscular structure and function. By combining research on muscle pain, which is a common clinical pain disease, we further provide a hypothesis concerning a dynamic feedback model of ＂weightlessness condition → muscular atrophy ←→ muscle pain＂. This may be useful to explore the neural mechanisms underlying the occurrence and development of muscular atrophy and muscle pain, through the key study of muscle spindle, and furthermore provide more effective therapy for clinical treatment.

Physiological effects of weightlessness: countermeasure system development for a long-term Chinese manned spaceflight

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.

EFFECT OF SIMULATED WEIGHTLESSNESS ON THE RESPONSE CHARACTERISTICS OF HUMAN BRAIN

In order to systematically investigate the effects of simulated weightlessness on thefunction state of human brain, 15° head-down tilt (HDT) was used to simulate weightless-ness, and the response changes of event-related EEG power spectra, medium-frequencysynchronous potentials and slow-waves were examined in the present study. It was foundthat HDT had characteristic effects on the above EEG responses, suggesting that the ef-fects mainly occurred in the brain’s regulatory system, therefore, resulting in changes ofthe brain function state.

Distribution of ^3H—nicotine in Rat Tissues Under the Influence of Simulated Microgravity

Rat tail suspension offers a useful model to reproduce physiologic responses to weightlessness.The present study was conducted in the head-down-tilt(HDT) rat model to assess changes in metabolism of body tissues employing 3H-nicotine. Twelve male rats were used in the study. Half of the rats were tail suspended at 30°for two weeks on a 12/12 light/dark cycle. During this period,body weight, food and fluid intakes were measured. At term, animals were anesthetized and injected IV withe a solution contaming 4 microuries of micotine. After 90 min the animals were sacrificed, exsanguinated and tissues (brain,blood,trachea,salivary gland,lung,heart,esophagus,spleen, kidneys and testes) were harvested. The distribution of 3H-nicotine per gram of each tissue was determinded and ealeulated as percent of total injected radioactivity. Final body weights of suspended ammals were significantly (P < 0.0 5) lower than those of eontrols(309±21 vs 350±11g). 3HNicotine waw retained in greatest amounts by the kindneys, followed inorder by salivary glands, spleen, and gastrointestinal tissues. compared to non-suspended control, the tissue retention of nicotine in suspended animals was decreased in the following tissues:esphyagus (25 %), aorta (25%). fundus (25%), trachea (22%), adrenals (18%), spleen (17 %), and pancreas (12 %). The decreased retention of mcotine in tissues from suspended animals may be indicative of the fluid shifts and changes in blood flow to those tissue beds. The lack of differnces in nicotine retention in liver and kidney between control and suspended groups may implicate a normal metabolic function of these organs even under simulated weightlessness.

Acclimation during spaceflight:effects on human emotion

Recently,studies on the extent to which spaceflight affects the psychology of individuals has received attention.In order to reveal the mental challenges that humans face in space,we need practical viewpoints to integrate the psychological effects,behavior,performance and the environment itself for space exploration.The present review discusses the individual variables related to space psychology and manned spaceflight,in addition to their growing trends.These items include patterns of emotional changes in extreme environments and the approaches to evaluating emotions.Moreover,the review concludes with suggested future research on emotion during spaceflight and its analogs.These data and information are needed to plan for the exploration of the Moon and Mars,along with contributions to the construction of the international space station(ISS) and astronaut training.

Corrosion Rate of Hydrogenation to C110 Casing in High H_2S Environment

The corrosion behavior of C110 bushing at high temperature and high pressure with a high H2S / CO2 was studied, and a basis for the materials selection of sour gas well bushing was provided in H2S, CO2 and saline coexisting environment. Under acidic condiction, hydrogen atoms greatly entered into the material and caused the material properties changed. Weight loss method was used to study the corrosion rate of hydrogen charging samples and original untreated samples in simulated oil field environment. PAR2273 electrochemical workstation was used to examine the electrochemical performance of samples untreated, hydrogen charging after reacting in autoclave. The corrosion product film was observed through SEM. The experimental results show that sample with hydrogen charging has a much more obvious partial corrosion and pitting corrosion than the untreated blank sample even the downhole corrosion speed of bushing is increased after being used for a period of time. Polarization curve shows the corrosion tendency is the same between sample with or without hydrogen charging and corrosion tendency is reduced by corrosion product film. A layer of dense product film formed on the surface of samples provides a certain protective effect to the matrix, but cracked holes which will accelerate partial corrosion of the sample were also observed.

Several Theoretical and Applied Problems of Human Extreme Physi­ology:Mathematical Modeling

Human cardiovascular system(CVS)and hemodynamics are critically sensitive to essential alterations of mechanical inertial forces in directions of head-legs(+Gz)or legs-head(-Gz).Typically,such alterations appear during pilotage maneuvers of modern high maneuverable airspace vehicles(HMAV).The vulnerability of pilots or passengers of HMAV to these altering forces depends on their three main characteristics:amplitude,dynamics,and duration.Special protections,proposed to minimize this vulnerability,should be improved in parallel with the increasing of these hazardous characteristics of HMAVs.Empiric testing of novel protection methods and tools is both expensive and hazardous.Therefore computer simulations are encouraged.Autonomic software(AS)for simulating and theoretical investigating of the main dynamic responses of human CVS to altering Gz is developed.AS is based on a system of quantitative mathematical models(QMM)consisting of about 1300 differential and algebraic equations.QMM describes the dynamics of both CVS(the cardiac pump function,baroreceptor control of parameters of cardiovascular net presented by means of lumped parameter vascular compartments)and non-biological variables(inertial forces,and used protections).The main function of AS is to provide physiologist-researcher by visualizations of calculated additional data concerning characteristics of both external and internal environments under high sustained accelerations and short-time microgravity.Additionally,AS can be useful as an educational tool able to show both researchers and young pilots the main hemodynamic effects caused by accelerations and acute weightlessness with and without use of different protection tools and technics.In this case,AS does help users to optimize training process aimed to ensure optimal-like human tolerance to the altered physical environment.Main physiological events appearing under different scenarios of accelerations and microgravity have been tested.

SPACE BIOMEDICAL STUDIES IN CHINA

Chinese scientists paid great attention to the study about space life science in 1996-1997.Several biomedical experiments in this field were completed in Chinese recoverable satellites or in a Russian biosatellite. The effect of microgravity and space radiation on Chinese silkworm eggs, plants, seeds and tomato DNA mutation was investigated in space. Head down bed rest of human body was applied to simulate weightlessness to study cardiovascular function, electrogastrogram,thermoregulation on the ground. Space motion sickness was also studied by means of swinging, optokinetic stimulation on the ground.

SPACE LIFE SCIENCE IN 2000-2001

Chinese scientists studied some of the problems in the field of space life science and achieved success in the area during 2000-2001. Space biological experi ments were carried out in the orbit and the results of ground studies on protein crystallization, space radiation, space motion sickness were introduced in this paper. The influences of simulated weightlessness on the brain-function, the car diovascular, endocrine hormones, immunity, skeletal and muscle systems were presented. In addition, gravity medicine and space environment medicine, as well as countermeasures to space deconditioning, such as the traditional Chinese medicine, were also reported.

THE TRACTION PROBLEM IN ELASTODYNAMICS

In continuum mechanics. Cauchy's six equationsare incomplete[1] and the famous Cauchy's laws of motionand TT =Twhere ρx, ρb , T and divT are continuous are also incomplete[2]. The first six equations are incomplete because the geometrical representation of deformation at a given point is as yet incomplete[3], and the last two laws are incomplete because b,T and divT are frame-indifferent, but ρx is not, and T is a symmetric, as Cauchy interpreted himself. Therefore, we say, the last two laws can't accommodate to the asymmetric tensor.The purpose of this paper is to complete Cauchy 's laws of motion by postulating an asymmetric tensor for the underlying traction field of 3-dimensional space on a general framing.

Advances in China Space Medical Experiment Research

In 2021,China Space Station(CSS)was assembled and constructed in-orbit,which provided a broad space platform for space medicine and space life sciences research.Space medicine focuses on the systematic risks that restrict long-term manned spaceflight.It carries out systematic research on the impact and countermeasure technology of long-term weightlessness on astronauts’health,space radiation on astronauts’health,behavior and ability,advanced on-orbit monitoring and medical disposal technology,and traditional space medical application technology by the space medicine experiment platform on human body and cell.It has accumulated valuable data on space environmental effects and human factors research,established a“human system risk”research system,obtained new knowledge and discoveries of space medicine,and explored countermeasure technologies of new characteristics.Moreover,a series of achievements have been made in the basic research on the mechanism of the special space environmental effect,which provides a solid foundation for the implementation of space missions.