Short-term response of primary human meniscus cells to simulated microgravity.

BACKGROUND: Mechanical unloading of the knee articular cartilage results in cartilage matrix atrophy, signifying the osteoarthritic-inductive potential of mechanical unloading. In contrast, mechanical loading stimulates cartilage matrix production. However, little is known about the response of meniscal fibrocartilage, a major mechanical load-bearing tissue of the knee joint, and its functional matrix-forming fibrochondrocytes to mechanical unloading events. METHODS: In this study, primary meniscus fibrochondrocytes isolated from the inner avascular region of human menisci from both male and female donors were seeded into porous collagen scaffolds to generate 3D meniscus models. These models were subjected to both normal gravity and mechanical unloading via simulated microgravity (SMG) for 7 days, with samples collected at various time points during the culture. RESULTS: RNA sequencing unveiled significant transcriptome changes during the 7-day SMG culture, including the notable upregulation of key osteoarthritis markers such as COL10A1, MMP13, and SPP1, along with pathways related to inflammation and calcification. Crucially, sex-specific variations in transcriptional responses were observed. Meniscus models derived from female donors exhibited heightened cell proliferation activities, with the JUN protein involved in several potentially osteoarthritis-related signaling pathways. In contrast, meniscus models from male donors primarily regulated extracellular matrix components and matrix remodeling enzymes. CONCLUSION: These findings advance our understanding of sex disparities in knee osteoarthritis by developing a novel in vitro model using cell-seeded meniscus constructs and simulated microgravity, revealing significant sex-specific molecular mechanisms and therapeutic targets.

[Potential use of thermoneutral «dry immersion¼ in oncological rehabilitation]. / Potentsial'noe ispol'zovanie termoneitral'noi «sukhoi immersii¼ v onkoreabilitatsii.

OBJECTIVE: To conduct an analytical review of the available literature data on thermoneutral «dry immersion¼ (TSI) - a method that simulates the state of weightlessness/microgravity. MATERIAL AND METHODS: The review included data from electronic databases: Scopus, Web of Science, MedLine, Wiley, World Health Organization, The Cochrane Central Register of Controlled Trials, ScienceDirect, PubMed, elibrary, CyberLeninka, disserCat. RESULTS: The extensive database of in vitro studies contains information on the reduction of cell proliferation, invasion, migration and increased apoptosis of thyroid, breast, lung, stomach, colon cancer cells, Hodgkin's lymphoma, glioblastoma, leukemia, melanoma, osteosarcoma of a human under the influence of microgravity. The vast majority of works are devoted to experiments on healthy people to finding out the mechanisms of action of long-term continuous microgravity. The study of the therapeutic effect of TSI as a physiotherapeutic procedure of one or repeated sessions was carried out by individual authors. Positive results of a short stay in the unsupported model were obtained in the treatment of children with perinatal disorders, cerebral palsy, patients with hypertension in a state of hypertensive crisis, Parkinson's disease, skin burn II gr. The results of the analytical review provide an opportunity to begin scientific research on the effectiveness and safety of thermoneutral «dry immersion¼ in the complex rehabilitation of cancer patients.

Protective effects of ginseng total saponins on reward-directed operant conditioning in hindlimb suspension rats / 数字中医药（英文）

Objective@#To explore the therapeutic effects of ginseng total saponins (GTSs) on cognitive impairments in astronauts caused by prolonged exposure to microgravity environment.@*Methods@#Fifty specific pathogen-free (SPF) male Wistar rats were randomized into control, hindlimb suspension (HLS), Huperzine A (HLS-Hup A 0.1 mg/kg), low-dose GTSs (HLS-GTSs 100 mg/kg), and high-dose GTSs (HLS-GTSs 200 mg/kg) groups, based on the completion time of reward-directed conditioning tasks. Except for rats in the control group, the others were subjected to HLS and treated with drugs (day 20 – 58), received reflex test under the condition of rewarding, and underwent Nissl body staining and Western blot detection on hippocampal.@*Results@#After modeling, rats in HLS group exhibited a reduction in the number of lever presses and an increase in the completion time of the reward-directed operant conditioning task Ⅰ (P < 0.05) when compared with the control group, which were not substantially altered in the HLS-GTSs 100 and 200 mg/kg groups (P > 0.05). In the reward-directed operant conditioning task Ⅱ, the HLS group rats demonstrated a marked decrease in the number of lever presses (P < 0.05) and nose pokes (P < 0.01) when compared with the control group rats; the HLS-GTSs 100 mg/kg showed a significant increase in the number of lever presses and nose pokes (P < 0.05), while the HLS-GTSs 200 mg/kg demonstrated a significant reduction in completion time and an elevation in the number of lever presses (P < 0.05) when compared with the HLS group rats. In visual signal discrimination task, compared with the control group rats, the HLS group rats showed decrease in the indexes of the visual signal discrimination(P < 0.01), while HLS-GTSs 100 and 200 mg/kg groups exhibited manifest increase in it (P < 0.01). In reward extinction experiment, the number of lever presses in HLS rats significantly increased when compared with the control group (P < 0.01); compared with the HLS group, HLS-GTSs 100 and 200 mg/kg groups demonstrated a marked descrease (P < 0.05). The expressions of N-methyl-D-aspartic acid receptor 1 (NR1) and phosophorylated N-methyl-Daspartic acid receptor 2B (p-NR2B) proteins were markedly decreased in rats in the HLS group (P < 0.05 and P < 0.01, respectively), while that of NR2B protein maintained the same (P > 0.05). GTSs increased the expression levels of p-NR2B (P < 0.01).@*Conclusion@#GTSs improved the learning and memory ability of complex operations by regulating the NR1/NR2B phosphorylation pathways in rats.

Responses of neuromuscular properties to unloading and potential countermeasures during space exploration missions.

We reviewed the responses of the neuromuscular properties of mainly the soleus and possible mechanisms. Sensory nervous activity in response to passive shortening and/or active contraction, associated with plantar-flexion or dorsi-flexion of the ankle joints, may play an essential role in the regulation of muscle properties. Passive shortening of the muscle fibers and sarcomeres inhibits the development of tension, electromyogram (EMG), and afferent neurogram. Remodeling of the sarcomeres, which decreases the total sarcomere number in a single muscle fiber causing recovery of the length in each sarcomere, is induced in the soleus following chronic unloading. Although EMG activity and tension development in each sarcomere are increased, the total tension produced by the whole muscle is still less owing to the lower sarcomere number. Therefore, muscle atrophy continues to progress. Moreover, walking or slow running by rear-foot strike landing with the application of greater ground reaction force, which stimulates soleus mobilization, could be an effective countermeasure. Periodic, but not chronic, passive stretching of the soleus may also be effective.

Inflammation is involved in response of gastric mucosal epithelial cells under simulated microgravity by integrated transcriptomic analysis.

Astronauts suffer from inflammatory changes induced by microgravity during space flight. Microgravity can significantly affect the inflammatory response of various cell types and multiple systems of the human body, such as cardiovascular system, skeletal muscle system, and digestive system. The aim of this research was to identify the key genes and pathways of gastric mucosa affected by microgravity. Human gastric mucosal epithelial GES-1 cells were cultured in a rotary cell culture system (RCCS) bioreactor to simulate microgravity. The gene expression profiles of GES-1 cells were obtained using Illumina sequencing platform and differentially expressed genes were identified by DESeq2 software, then Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were performed. Subsequently, a protein-protein interaction (PPI) network was constructed. Compared with a normal gravity (NG) group, a total of 943 DEGs, including 192 downregulated genes and 751 upregulated genes, were identified. These DEGs were associated with findings that included response to interleukin-1, positive regulation of inflammatory response, and positive regulation of neuroinflammatory response. Furthermore, these DEGs were mainly enriched in herpes simplex virus 1 infection, cytokine-cytokine receptor interaction, and NOD-like receptor signaling pathway. Thus, 21 hub genes were identified from PPI network, including IL6, IL1B, ITGAM, CXCL8, ITGAX, CCL5, SERPINA1, APOE, CSF1R, VWF, GBP1, APOB, CYBB, HLA-DRB1, CD68, FGG, FGA, OASL, NOD2, OAS2 and FCGR2A. These findings suggested that simulated microgravity upregulated inflammation-related genes and pathways of GES-1 cells, which may play important roles in the response to microgravity and provide useful information for preventing mucosal damage in astronauts. In conclusion, this study revealed the key genes and pathways associated with simulated microgravity and indicated that simulated microgravity induced an inflammatory response in gastric mucosal epithelial cells.

[Study of thermal injury effects on human HaCaT cells under simulated microgravity environment].

Objective: To investigate the thermal injury effects on human HaCaT cells under simulated microgravity environment. Methods: The human HaCaT cells were collected and divided into simulated microgravity thermal injury (SMGTI) group, normal gravity thermal injury (NGTI) group, and normal gravity false injury (NGFI) group according to the random number table. Cells in NGTI and NGFI groups were cultured routinely in culture bottle, and cells in SMGTI group were cultured in the rotary cell culture system to simulate microgravity environment. Cells in SMGTI and NGTI groups were bathed in hot water of 45 ℃ for 10 minutes to make thermal injury model, and cells in NGFI group were bathed in warm water of 37 ℃ for 10 minutes to simulate thermal injury. At post injury hour (PIH) 12, cell morphology of 3 groups was observed under inverted phase contrast electron microscope. At PIH 2, 6, and 12, single cell suspension in the 3 groups was collected to detect the cell cycle by flow cytometer and the mRNA expressions of heat shock protein 70 (HSP70), matrix metalloproteinase 9 (MMP-9), and cysteine-aspartic protease 3 (caspase-3) by real time fluorescence quantitative reverse transcription polymerase chain reaction, and the experiments were repeated for 3 times. At PIH 2, 6, and 12, cell culture supernatant in the 3 groups was collected to detect the concentration of heparin-binding epidermal growth factor (HB-EGF) by enzyme linked immunosorbent assay method, the experiment was repeated for 3 times. The sample in each group and each time point was 3. Data were statistically analyzed with analysis of variance for factorial design, one-way analysis of variance, least significant difference test, Kruskal-Wallis H test, and Mann-Whitney U test. Results: (1) At PIH 12, cells in NGFI group showed regular shape and regular arrangement, with no cell debris. The cell shape in NGTI group was generally regular, with fewer cell debris and closer arrangement than that in NGFI group. The cells in SMGTI group showed more irregular shapes, different sizes, and dead cell debris. (2) The percentage of G1 phase cells in NGTI group was significantly higher than that in NGFI group and SMGTI group at PIH 2, respectively (P<0.05), and the percentage of G1 phase cells in NGTI group was significantly lower than that in NGFI group and SMGTI group at PIH 6 and 12, respectively (P<0.05). The percentage of G2/M phase cells in NGTI group was significantly lower than that in SMGTI group at PIH 2 (P<0.05), and the percentage of G2/M phase cells in NGTI group was significantly higher than that in NGFI group and SMGTI group at PIH 6 and 12, respectively (P<0.05). The percentage of S phase cells in NGTI group at PIH 2, 6, and 12 was significantly higher than that in SMGTI group (P<0.05), and the percentage of S phase cells in NGTI group at PIH 2 and 6 was significantly lower than that in NGFI group (P<0.05). (3) The HSP70 mRNA expressions of cells in NGTI group were 2.50±0.30 and 3.99±0.35 at PIH 2 and 6, which were significantly higher than 1.14±0.15 and 0.82±0.27 in NGFI group (P<0.05), and 1.17±0.53 and 1.65±0.59 in SMGTI group (P<0.05). The MMP-9 mRNA expression of cells in SMGTI group was significantly higher than that in NGTI group at PIH 2, 6, and 12, respectively (Z=-2.319, -2.882, -2.908, P<0.05). At each time point after injury, the mRNA expression of caspase-3 of cells in NGTI group was similar to that in NGFI group and SMGTI group, respectively (P>0.05). (4) The concentration of HB-EGF in cell culture supernatant of NGTI group was significantly lower than that in NGFI group at PIH 2, 6 and 12 (P<0.05), and the concentration of HB-EGF in cell culture supernatant of SMGTI group was significantly higher than that in NGTI group at PIH 2 and 6 (P<0.05). Conclusions: The proliferation and secretion functions and expression of wound repair related protein of human HaCaT cells inflicted with thermal injury in simulated microgravity environment showed complex and diversified changes, which provide theoretical basis for further research on damage repair under weightlessness.

Alteration of Cytoskeleton Morphology and Gene Expression in Human Breast Cancer Cells under Simulated Microgravity.

OBJECTIVE: Weightlessness simulation due to the simulated microgravity has been shown to considerably affect behavior of tumor cells. It is aim of this study to evaluate characteristics of human breast cancer cells in this scaffoldfree 3D culture model. MATERIALS AND METHODS: In this experimental study, the cells were exposed to simulated microgravity in a randompositioning machine (RPM) for five days. Morphology was observed under phase-contrast and confocal microscopy. Cytofilament staining was performed and changes in expression level of cytofilament genes, proliferation/differentiation genes, oncogenes and tumor suppressor genes were detected by quantitative reverse transcription polymerase chain reaction (qRT-PCR), followed by western blot confirmation. RESULTS: After five days, distinct spheroid formation was observed. Rearrangement of the cytoskeleton into spherical shape was visible. VIM gene expression was significantly up-regulated for adherent cells and spheroids (3.3x and 3.6x respectively, P<0.05 each). RHOA also showed significant gene up-regulation for adherent cells and spheroids (3.2x and 3.9x respectively, P<0.05 each). BRCA showed significant gene up-regulation in adherent cells and spheroids (2.1x and 4.1x respectively, P<0.05 each). ERBB2 showed significant gene up-regulation (2.4x, P<0.05) in the spheroids, but not in the adherent cells. RAB27A showed no significant alteration in gene expression. MAPK) showed significant gene up-regulation in adherent cells and spheroids (3.2x, 3.0x, P<0.05 each). VEGF gene expression was down-regulated under simulated microgravity, without significance. Alterations of gene expressions could be confirmed on protein level for vimentin and MAPK1. Protein production was not increased for BRCA1, human epidermal growth factor receptor 2 (HER2) and VEGF. Contradictory changes were determined for RHOA and its related protein. CONCLUSION: Microgravity provides an easy-to handle, scaffold-free 3D-culture model for human breast cancer cells. There were considerable changes in morphology, cytoskeleton shape and gene expressions. Identification of the underlying mechanisms could provide new therapeutic options.

Effect of simulated microgravity on the photopic negative response of flash electroretinogram in adult mice / 中华眼底病杂志

Objective To observe the effect of simulated microgravity on the photopic negative response (PhNR) of full-field flash ERG in adult mice.Methods In an experimental study,forty-eight adult male C57BL/6J mice (48 eyes) were randomly divided into model and control groups.Model mice were further divided into three subgroups of 8 each:tail-suspended for 15 days (subgroup A),tail-suspended for 30 days (subgroup B),and tail-suspended for 30 days followed by returning to normal position for 30 days (subgroup C).The three control subgroups were similarly fixed with a harness but kept in the normal position for corresponding periods of 15,30,and 60 days.The mice were immediately examined using ERG-PhNR,flash VEP,OCT and visually-guided behavior in vivo,and subsequently sacrificed to analyze the retinal histology in vitro.PhNR amplitude was measured from baseline to PhNR trough.N1 peak-time and N1-P1 amplitude of VEP was analyzed.The escape duration was used to quantitatively evaluate the visual function of mice.In addition,inner retinal thickness was analyzed by OCT imaging.Data were compared by the independent sample t-test.Results PhNR amplitude in the model subgroup A was obviously lower than the corresponding control subgroup,the difference was statistically significant (t=-3.196,P＜0.01).There was no significant difference in PhNR amplitude between the model subgroup B or C and the corresponding control subgroup (t=-1.976,0.285;P＞0.05).There was no significant difference in FVEP N1 peak-time or N1-P1 amplitude between any of the three model subgroups and the corresponding control subgroup (P＞0.05).There was no significant difference in OCT-measured inner retinal thickness between any of the three model subgroups and the corresponding control subgroup (t=-0.461,2.073,-0.402;P＞0.05).The three model subgroups showed almost normal retinal structure,including the retinal ganglion cell,inner pexiform layer,inner nuclear layer,outer plexiform layer,outer nuclear layer,ellipsoid zone and RPE.There was no significant difference in visually-guided escape time between any of the three model subgroups and the corresponding control subgroup (t=-0.637,-0.955,1.297;P＞0.05).Conclusion Via tail-suspension,short-term simulated microgravity can affect the PhNR of flash ERG;however,the change is reversible and does not affect visual function of mice.

Morphological changes on cochlear hair cells of rats in simulated weightlessness and inboard noise / 北京大学学报(医学版)

Objective: To observe the morphological changes on cochlear hair cells of rats in simulated weightlessness and inboard noise and to investigate the different changes in three turns of hair cells.Methods: Thirty-two healthy SD rats, all males, were randomly divided into four groups: control group, weightlessness group, noise group and weightlessness+noise groups (n=8).Then rats were exposed to-30° head down tilt as simulated weightlessness and inboard noise including steady-state noise which was (72±2) dB SPL and impulse noise up to 160 dB SPL in spaceship environment.The control group was kept in normal condition for 8 weeks.Bilateral auditory brainstem response (ABR) thresholds were tested before and after exposure respectively, and immunofluorescence staining and scanning electron microscopy (SEMs) of basilar membrane were applied after exposure.Results: ABR threshold shifts of each group were higher after exposure.There was difference between ABRs of the experiment groups before and after exposure (Pnoise group>weightlessness group>control group and the damage degree of the four turns of hair cells: basal turn>mid turn>top turn.Conclusion: The rats exposed to the above environment for 2 weeks displayed obvious changes in cochlea morphology, and the weightlessness+noise group had the most obvious damage.

Effects of simulated microgravity on miRNA expression in mouse fibroblasts / 中华创伤杂志

Objective To investigate the effects of simulated microgravity by rotary cell culture system (RCCS) on expression profiles of miRNA in mouse fibroblasts L929 cell line.Methods L929 cells were cultured in vitro and divided into simulated microgravity (SMG) group and normal gravity (NG) group according to the simple random method.Samples of two groups were collected on 7th day of culture and the total RNAs were extracted,labeled,and hybridized in sequence.Feature Extraction Software was used to collect the array images and get raw data,which were analyzed by Genespring Software.Differentially expressed miRNAs were identified and then validated by qRT-PCR.Target genes of differentially expressed miRNAs were predicted by the databases of Targetscan and microRNAorg,and the intersections of databases were identified as potential regulatory target genes.Gene ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) analysis were applied to determine the roles of these target genes.Relevant biological functions and/or signaling pathways of the regulated genes especially related with wound healing process were categorized based on their enrichments.Then integration predictions of the miRNA and mRNA expression profiles had been proposed to refine the functional miRNA-mRNA relationships.The miRNA-mRNA functional network and miRNA-mRNA control network were constructed.Results Four miRNA genes were up-regulated significantly including mmumiR-669j,-122-5p,-30a-3p,-6516-3p,among which mmu-miR-669j was up-regulated at 52.84 folds with the greatest significance (P ＜ 0.05).Seventeen miRNA genes were down-regulated significantly including mmu-miR-21a-3p,-miR-28a-5p,-218-5p,-210-3p,-miR-19a-3p,-miR-31-3p,and-miR-19b-3p,among which mmu-miR-28a-5p was down-regulated at 15.47 folds with the greatest significance (P ＜ 0.05).The qRT-PCR showed a high concordance with the microarray results (P ＜ 0.05).Target gene prediction and functional enrichment analysis suggested that a variety of biological processes and signaling pathways involved in wound repair were significantly enriched (P ＜ 0.05).Function network and regulation network of miRNA-mRNA covered all the differentially expressed miRNAs,which suggested that miR-21 a-3p and predicted target gene Smad3 might play an important role in wound healing under microgravity.Conclusions Simulated microgravity by RCCS can significantly affect the expression of stress-related miRNAs in mouse fibroblasts L929.The miRNA target gene prediction and functional enrichment analysis based on gene chip technology may provide theoretical basis for illustrating the mechanism and management of weightlessness stress injury.

Effects of simulated noise-weightlessness combined factors in spaceship on auditory function of rats after a medium-long term / 中国耳鼻咽喉头颈外科

OBJECTIVE To investigate the effects of simulated noise-weightlessness combined factors on auditory brainstem response thresholds and the cochlear structure after a medium-long term (2-8 weeks). METHODS Healthy adult rats were randomly divided into male/female experimental and control groups. The male and female experimental groups were exposed to simulated noise-weightlessness environment and exerted impulse noise exposure at the end. Auditory brainstem response (ABR) threshold was recorded at the beginning, the 2nd, 4th and 8th weeks and after impulse noise exposure exerting. The cochlea was also examined by scanning electron microscopy each time after ABR threshold record. RESULTS ABR thresholds in experimental groups after impulse noise exposure were significantly increased (P<0.05). Female experimental group were lower than those of the male experimental group at 2 and 4 weeks (P<0.05). Scanning electron microscope observation showed that the inner and outer hair cell were losing and lodging, and the longer exposed to the compound factors, the heavier pathological changes observed on the cochlear hair cell. CONCLUSION Noise-weightlessness combined factors can cause the morphology and function damage of rat cochlear in medium-long term. The damage of impulse noise was more than steady noise on rat auditory function. Sex differences was also observed. Rat cochlear hair cell pathological changes increased with the exposed time.

Effect of simulated null gravity on the secretion of adrenomedullary hormones and miRNA-375 expression in rats / 解放军医学杂志

Objective To investigate the effects of simulated null gravity on the secretion of adrenomedullary hormones and miRNA-375 expression in rats. Method Fifty-six healthy adult male Wistar rats were randomly divided into 7 experimental groups (8 each), including suspension for 6h, 12h, 1d, 3d, 5d, 7d and 0h (control). Tail-suspension was used to establish the weightlessness animal model according to Morey-Holton's method. At the end of the experiment, the blood samples were obtained from the postorbitor vein, and the bilateral adrenal glands were harvested. The serum concentrations of catecholamines were determined by radioimmunological analysis. The expression of TH mRNA and miRNA-375 were assessed by quantitative RTPCR. TH protein in adrenal medulla was assayed using Western blotting analysis and immunohistochemistry. Results(1) The serum concentrations of rat's adrenomedullary hormones fluctuated obviously during the period of tail-suspension simulated weightlessness, with a temporary decline during 6-12h, followed by a sharp increase with a peak value on the 3rd day of suspension. (2) RT-PCR assay showed that TH mRNA expression in adrenal medulla of rats also fluctuated obviously, with a temporary decline at 6h and then elevated with a peak value at 1 day of suspension, followed by a downward trend forming a trough value on 5d of suspension. The immunohistochemistry showed that TH protein was stained as brown particles and the cytoplasm of adrenal medulla was stained deeply on 3d of suspension. (3) RT-PCR assay revealed that the expression of miRNA-375 in adrenal medulla increased temporarily at 6h of suspension, and it decreased significantly during 12h to 3d of suspension compared with that of control group (P<0.05). The miRNA-375 expression was up-regulated again during sustained suspension with a significant increase on 7d of experiment compared with that of control group (P<0.05). Conclusion The simulated weightlessness could affect the secretion of hormone of adrenal medulla in rats, and it may be related to the regulation of TH through miRNA-375 messenger network.

Effect of simulated microgravity on biological characteristics of Klebsiella pneumoniae / 军事医学

Objective To investigate the effect of simulated microgravity on growth , morphology, protein expression and virulence gene expression of Klebsiella pneumoniae (KPN).Methods KPN was divided into simulated microgravity group and control group in the experiment .The former group was in the ambient of simulated microgravity in a clinostat .The bacterial growth curves , morphologyical changes in electron microscopy , and protein expression were detected by SELDI-TOF-MS, and the expression of 4 virulence genes(ureA,wabG,uge and fimH) by real-time fluorescence quantitative PCR (RT-PCR) in both groups.Results Compared with the control group , the growth of KPN under simulated microgravity was accelerated , and the total bacterial count increased in microgravity group .The bacterial morphology in microgravity group was changed under scanning electron microscopy (SEM), and thinner and longer bacteria were increased .The transmission electron microscopy ( TEM) analysis revealed increase in cytoplasmic granular substance in microgravity group .Proteome analysis showed that the expression of 18 proteins was changed , half of which up-regulated and the rest were down-regula-ted.Those 18 proteins were searched in the protein library .And 21 proteins of a similar molecular mass were retrieved ,13 of which,proteins with known functions ,were closely related to bacterial life activities .RT-PCR results showed that four virulence genes of KPN were down-regulated.Conclusion Upon exposure to simulated microgravity , the growth and repro-duction of KPN are accelerated and enhanced .The bacterial morphology is changed .The strain′s protein expression and four virulence genes expressionare also changed .Therefore,microgravity can change the characteristics of KPN .

Effect of 72h weightlessness simulation on processing speed of mental rotation of males / 中华行为医学与脑科学杂志

Objective To explore the effect of weightlessness simulation on processing speed of mental rotation of males in 72 h head-down tilt,in order to further reveal human performance changes caused by weightlessness.Methods During 72 h weightlessness simulation (9 am day 1 to 9 pm day 4,head-down tilt started from 9 pm day 1),16 male subjects were processed speed of rotation data byhand picture mental rotation (test 8 times),using self cross-references design,and the variation of processing speed of mental rotation by duration was analyzed.Results The linear regression analysis showed,the reaction time of each time point for each subject as the independent variable,the angle of rotation as the dependent variable,with the extension of simulated weightlessness time.The intercept(constant term of the regression equation),indicating the processing speed of non-rotation,were gradually increased with HDT time,but didn(t) reached significantly difference (F(3,14) =0.551,P =0.650) ;the slope(Regression coefficient of the regression equation),indicating the processing speed of rotation.were gradually increased with HDT time,and reached the significantly difference (F(3,14) =4.338,P =0.009).The value of intercept and slope was like upside-down U in three days,and reached the highest value at day 2.Conclusion Weightlessness simulation have affection on the speed of mental rotation,especially on the rotation speed.

Osteoblast cytology study in simulated weightless condition: A review / 第二军医大学学报

Osteoblasts are the most important mechanoreceptive and osteogenic cells. The loss of bone in microgravity is mainly due to the dysfunction of osteoblasts. Research on osteoblast cytology under simulated weightlessness has made great progress in recent years. Current experiments are focusing on the changes in the cellular proliferation, differentiation,apoptosis, function and signal transduction in osteoblasts. This paper reviews the progress of the studies in this field.

Comportamento mecânico do terço proximal de fêmures de ratos após período de suspensão pela cauda e exercitação / Mechanical behavior of rats' femoral proximal thirds after a period of tail suspension and exercises

A remodelação óssea pode ser estimulada por forças mecânicas presentes nas atividades físicas normais. Neste trabalho foi analisado o comportamento mecânico do terço proximal de fêmur de ratas submetidas à suspensão pela cauda e posterior treinamento em esteira. Sessenta e seis ratas da raça Wistar foram usadas. Primeiramente os animais foram criados por noventa dias e divididos em cinco grupos (dois controles e três experimentais). Os animais do grupo Controle I foram sacrificados com 118 dias de idade. No grupo S (suspenso) os animais foram suspensos pela cauda por 28 dias e sacrificados. No grupo Controle II os animais foram sacrificados com 139 dias de idade. No grupo S-L (suspenso-liberado) as ratas foram liberadas 21 dias após a suspensão. No grupo S-T (suspenso-treinado) após o período de suspensão os animais passaram por treinamento em esteira durante 21 dias. Para análise do comportamento mecânico do osso foi aplicada uma força vertical na cabeça femoral até a ruptura. A fratura foi analisada por raios-X. A suspensão causou um decréscimo da força máxima e, o treinamento e a liberação após a suspensão causaram a recuperação das propriedades mecânicas. Mas, o padrão de fratura não apresentou diferença entre os grupos experimentais.

Bone remodeling can be stimulated by mechanical forces present in normal physical activities. In the present research, we investigated the mechanical behavior of the proximal femur of rats previously maintained in tail suspension and later, submitted to physical exercise on a treadmill. Sixty-six Wistar rats were used. Firstly, the animals were raised until the age of ninety days and then divided into five groups (two control groups and three experimental groups). The animals allocated to Control I group were killed at 118 days of age. In the S group, the animals were suspended by tail for 28 days. In Control II group, the animals were killed at 139 days of age. In group S-L (suspended and released) the rats were kept free for 21 days after tail suspension. In group S-T (suspended and trained), after tail suspension period, the rats were trained in a treadmill for 21 days. For analysis of the mechanical behavior of the bone, force was applied on the femoral head until failure. The fracture was evaluated by x-ray. Suspension caused a decrease of the maximum load and, treadmill training and post-suspension release caused the recovery of mechanical properties. But, the fracture line pattern did not show any difference among the experimental groups.

Indirect Evaluation of Sarcoplasmic Reticulum Ca~(2+) Release Function in Skeletal Muscle Strips / 航天医学与医学工程

Objective To set up a simple method to measure the SR Ca2+ release function in skeletal muscle strips.Methods The time from peak tension to 75 % relaxation(TR75) during intermittent tetanic contraction(fatigue contraction) of isolated musculus soleus strips was analyzed.It was prolonged rapidly,and then shortened slowly.The ratio of maximal TR75 to initial TR75(R-TR75) indicated a balance between SR Ca2+ release and uptake.If the SR Ca2+-ATPase(SERCA) activity and inhibition extent of SERCA in fatigue contraction were identical,R-TR75 should be an index for SR Ca2+ release function.Results Higher stimulation voltage or 5 mmol/L caffeine perfusion which increased the SR Ca2+ release channel open probability induced an increase of R-TR75 from 2.5 in control to 3.0.On the contrary,inhibition of SR Ca2+ release with 5 mmol/L magnesium sulfate perfusion significantly decreased R-TR75.Inhibition of SR Ca2+ release by metabolites during fatigue contraction was recovered slowly.So R-TR75 at the second fatigued contraction was reduced after 5 or 10 min of recovery,but no significant difference after 60 min of recovery.During intermittent tetanic contraction R-TR75 was increased to be 2.9 times of normal in unloaded soleus.Conclusion The above results suggest that R-TR75 during muscle strip fatigue contraction without any change of SERCA activity can indirectly reflected SR Ca2+ release function.In 2-week unloaded soleus,the enhanced R-TR75 indicates an increase in SR Ca2+ release function.

Effects of Digoxin on Cardioventricular Function in Rats after Simulated Weightlessness / 航天医学与医学工程

Objective To investigate the protective effects of Digoxin on cardioventricular function in rats after simulated weightlessness.Methods Eighty rats were divided randomly into 5 groups:control(Con)group,tail-suspended+sham feeding(TS+SF)group,tail-suspended+Digoxin 2 wk(TS+D2)group and tail-suspended+Digoxin 3 wk(TS+D3)group.The TS+SF group was given the distilled water.At the end of tail-suspended for 3 weeks,the heart function of 10 rats in each group was examined with echocardiography.The level of atrial natriuretic polypeptide(ANP)in serum was measured with immunoradiometric assay in other 6 rats.Results Compared with TS+SF group,the contractile function of LV improved in TS+D2 and TS+D3 groups(P0.05).Conclusion Digoxin can improve muscle contractile and blood ejection of LV and retard the tendency of atrophy in simulated weightlessness.

Ameliorated Effects of High Frequency Sinusoidal Vibration Given to Soleus Muscle on H Reflex in Rats Under Tail Suspension / 航天医学与医学工程

Objective To observe the changes in excitability of alpha-motoneuron responding to the muscle spindles afferent excitability in the model rats and explore whether the changes in this excitability to be changed as high frequency sinusoidal vibration acted on the soleus muscle.Methods The simulated weightlessness model was created by the tail-suspension.Mechanical vibrations at a frequency of 100 Hz with amplitude of 0.3 mm were acted on soleus muscle.The electromyogram of soleus muscle evoked by electrical stimulation of the sciatic nerve was recorded in control rats and HS rats.Results It was showed that HS and HFV did not influence the tendency of changes in amplitude of H reflex when the stimulation intensity increased.However,after 14-day HS,mean maximal motor response(Mmax)and mean maximal monosynaptic reflex/Mmax(Hmax/Mmax)both significantly decreased,respectively(P0.05).Conclusion It is suggested that HS should lead to the decrease in motoneurons excitability which is resulted from the reduction of muscle spindle afferent.HFV acted on soleus muscle of rats can improve the excitability of alpha-motoneurons in spinal cord during hindlimb suspension.