The perception of verticality in lunar and Martian gravity conditions

Although the mechanisms of neural adaptation to weightlessness and re-adaptation to Earth-gravity have received a lot of attention since the first human space flight, there is as yet little knowledge about how spatial orientation is affected by partial gravity, such as lunar gravity of 0.16 g or Martian gravity of 0.38 g. Up to now twelve astronauts have spent a cumulated time of approximately 80 h on the lunar surface, but no psychophysical experiments were conducted to investigate their perception of verticality. We investigated how the subjective vertical (SV) was affected by reduced gravity levels during the first European Parabolic Flight Campaign of Partial Gravity. In normal and hypergravity, subjects accurately aligned their SV with the gravitational vertical. However, when gravity was below a certain threshold, subjects aligned their SV with their body longitudinal axis. The value of the threshold varied considerably between subjects, ranging from 0.03 to 0.57 g. Despite the small number of subjects, there was a significant positive correlation of the threshold with subject age, which calls for further investigation.     

模拟失重对雄性大鼠骨流变特性的测试

目的研究模拟失重对大鼠承重骨流变特性的影响,为航天医学提供模拟失重动物骨流变参数。方法30只Wistar雄性大鼠,随机分为正常对照组15只和头低位30°尾吊组(失重模型组)15只。实验第28天时取两组动物股骨进行压缩应力松弛、蠕变实验。结果得出了正常对照组和失重模型组大鼠股骨压缩应力松弛、蠕变数据和曲线,得出了两组大鼠股骨的归一化应力松弛函数,归一化蠕变函数与曲线,以一元线性回归分析的方法处理实验数据,得出了回归系数a、b与c、d值和归一化应力松弛函数G(t)、归一化蠕变函数J(t)表达式,还得出了两组大鼠股骨应力松弛、蠕变与时间的变化规律。结论失重模型组大鼠股骨应力松弛、蠕变量低于正常对照组。     

模拟失重及飞船舱内噪声复合因素对豚鼠免疫功能的影响

目的:探讨模拟失重及飞船舱內噪声复合因素条件对豚鼠免疫功能的影响.方法:选用健康、白色、红目豚鼠34只,随机分为对照组8只,单纯模拟失重组11只和模拟失重+噪声组和15只.失重采用后肢悬吊法,身体纵轴与水平线呈-30°.噪声组暴露于模拟失重及飞船内噪声环境,连续刺激5d.免疫指标采用T淋巴细胞增殖比值,标本取自脾脏组织,采用MTT法,测定T淋巴细胞平均增殖比值.结果:T淋巴平均增殖率比值:模拟失重+噪声复合因素组为:0.403±0.331;模拟失重组为:0.894±0.327;对照组1.321±0.431.失重+噪声组和单纯失重组及对照组比较,T淋巴细胞增殖率均下降,其结果差异有极显著性(P＜0.01),单纯失重组和对照组比较,T淋巴细胞增殖率下降,其结果差异有显著性(P＜0.05).结论:模拟失重+飞船舱內噪声复合因素及单纯失重均可使T淋巴细胞增殖率下降,前者使T淋巴细胞增殖率下降更为明显.     

五加补骨方及阿仑膦酸钠对模拟失重大鼠骨丢失干预比较

目的:比较五加补骨方及阿仑膦酸钠对3周尾吊模拟失重大鼠前后肢骨胳及肌肉丢失的干预作用.方法:自2009年3月至5月,6周龄雄性Wistar大鼠40只,按体重用随机区组法分为:五加补骨方组(HUC)、阿仑膦酸钠组(HUA)、空白组(CON)、模型组(HU),每组10只.动物实验周期为4周,HUC组全程给予五加补骨方(含刺五加、熟地黄、怀牛膝、牡蛎等)水煎剂,按体重10 ml/kg剂量每日灌胃1次,药液浓度0.704 g/ml;HUA组全程给定量阿仑膦酸钠片溶解混悬剂灌胃,按体重10 ml/kg剂量每周灌胃1次,药液浓度0.9 mg/ml;CON组和HU组均以上述方法全程给予蒸馏水.自第2周始,HU、HUC、HUA组均以尾部悬吊模拟失重3周.第4周末处死大鼠,分别测量血清钙、磷含量及碱性磷酸酶活性(ALP),肱骨和股骨骨密度(BMD)、肱骨和胫骨生物力学性能(biomechanical property)以及肱二头肌和腓肠肌重量指数.结果:与CON组比较,HU组血清Ca显著升高(P＜0.05),后肢BMD、力学性能及肌肉指数均显著降低(P＜0.01);与CON组比较,HUA组血清Ca显著升高(P＜0.05).HUC组血清ALP显著高于其他3组(P＜0.01).与HU组比较,HUC组及HUA组股骨BMD均显著升高,胫骨最大载荷、最大桡度及弹性载荷均有升高趋势;与HU组相比,HUC组及HUA组腓肠肌萎缩分别缓解12.5%和50%(P＞0.05),肱骨BMD均无显著变化,而HUA组肱骨最大桡度(P＜0.01)及弹性桡度(P＜0.05)均较HU组有显著降低.结论:中药复方和阿仑膦酸钠均可有效抑制模拟失重造成的后肢骨及肌肉丢失,改善其力学结构.中药复方在缓解上肢力学性能改变方面表现出一定优势.在治疗航天失重骨丢失类疾病上,五加补骨方与阿仑膦酸钠效果相当.     

Space motion sickness

Motion sickness remains a persistent problem in spaceflight. The present review summarizes available knowledge concerning the incidence and onset of space motion sickness and aspects of the physiology of motion sickness. Proposed etiological factors in the elicitation of space motion sickness are evaluated including fluid shifts, head movements, visual orientation illusions, Coriolis cross-coupling stimulation, and otolith asymmetries. Current modes of treating space motion sickness are described. Theoretical models and proposed ground-based paradigms for understanding and studying space motion sickness are critically analyzed. Prediction tests and questionnaires for assessing susceptibility to space motion sickness and their limitations are discussed. We conclude that space motion sickness does represent a form of motion sickness and that it does not represent a unique diagnostic entity. Motion sickness arises when movements are made during exposure to unusual force backgrounds both higher and lower in magnitude than 1 g earth gravity.     

不同体位短臂离心机暴露时心血管及前庭功能的改变

目的 通过观察和比较不同体位下短臂离心机暴露所引起的心血管及前庭功能反应,进一步明确短臂离心机暴露下体位因素对心血管和前庭功能的影响. 方法 10名健康男性,依次进行75°、45°、15°后倾体位的短臂离心机暴露,且每体位先后进行2 G、3 G(足水平)人工重力暴露;采用便携式无创逐跳血压监测仪(Portapres)全程监测,并记录受试者血压、心率,通过Beatscope分析软件计算心脏泵血功能和总外周阻力;同时进行前庭功能评价,比较不同体位短臂离心机暴露对心血管、前庭系统的影响. 结果 2 G、3 G短臂离心机分别暴露时,15°体位下6名受试者出现严重运动病症状被迫终止试验;75°和45°两种体位下受试者血压、心率较基础值增高(F=2.79～16.44,P<0.05);心输出量则无显著变化.3 G暴露75°和45°两种体位时,每搏量显著降低(F=2.25、8.35,P<0.05).3 G暴露45°体位时总外周阻力较基础值增高(F=2.61,P<0.05);相同G值短臂离心机暴露时,75°体位下心血管功能变化较45°体位差异无统计学意义,而前庭功能评分则随着体位角度的减小而逐渐增高,15°体位下评分较45°和75°体位增高,差异有统计学意义(P<0.05). 结论 短臂离心机暴露时,45°和75°两种体位对心血管功能的影响无统计学意义,但不同体位对前庭功能的影响却差异较大.暴露体位越趋近于坐位,引起的运动病程度越重. Abstract： Objective To investigate the changes of human cardiovascular and vestibular functions when exposed to the artificiaI gravity generated by short-arm centrifuge with different body positions.Methods Ten healthy male volunteers were exposed to the artificial gravity at three different body positions:foot towards to the radial direction off the rotation center respectively with 75°,45°and 15°back tilting.Each position underwent on short-arm centrifuge with two sessions that were at 2 G and 3 G (at foot level) respectively.Beat-by-beat arterial blood pressure (BP) and heart rate (HR) were measured before and during the experiment by means of Portapres and calculated parameters,such as stroke volume (SV),cardiac output (CO) and total peripheral resistance (TPR),were obtained by Beatscope software.A subjective scoring was taken for assessing vestibular sensations. Results Six of 10 subjects with 15°posture were terminated both in 2 G and 3 G exposure due to their serious motion sickness symptoms.Comparing to the measurements before exposure,subjects with 45°and 75°posture showed significant increased BP and HR (F=2.79 to 16.44,P<0.05) but SV (F=2.25 or 8.35,P<0.05) while CO had no obvious change.Comparing to the measurements before exposure,subjects with 3 G (45°posture) showed significant incleased TPR (F=2.61,P<0.05).3 G exposure resulted in higher HR than that in 2 G.No significant changes of BP,HR,CO,SV and TPR were found between 45°and 75°postures under same exposure.The scores of vestibular assessment showed increased tendency with the decreased tilt angle.Significantly higher scores were got for 15°posture exposures comparing to others and indicated stronger vestibular stimuli.Conclusions The results suggested that the smaller tilted angle posture would result in mole serious vestibular symptoms.     

模拟失重环境碱性成纤维细胞生长因子对人牙周膜成纤维细胞增殖的影响

目的 探讨在模拟失重环境下碱性成纤维细胞生长因子(bFGF)对人牙周膜成纤维细胞(hPDLF)增殖的影响. 方法 试验分对照组、模拟失重组和模拟失重加hPDLF组3组.采用酶消化组织块培养法分离、培养原代hPDLF.应用噻唑蓝比色法,检测模拟失重条件下,不同时间和不同浓度的bFGF对hPDLF增殖的影响. 结果 在模拟失重12h、24h组hPDLF增殖较对照组没有显著差别,在48h、72h模拟失重组较对照组显著降低,差异有统计学意义(t=7.303、8.668,P<0.01).模拟失重48 h时bFGF浓度在50～100μg/L范围内加bFGF组hPDLF增殖高于模拟失重组,差异有统计学意义(P<0.05),而bFGF浓度为1～10μg/L时,两组没有显著差别. 结论 模拟失重在48 h、72 h对hPDLF的增殖有抑制作用,模拟失重环境bFGF浓度在50～100μg/L范围内具有促进hPDLF增殖的效应.     

模拟微重力对大鼠嗜铬细胞瘤细胞蛋白酪氨酸硝基化的影响

目的研究微重力状态下活性氮自由基（RNS）对神经细胞蛋白质氧化修饰的影响。方法以大鼠嗜铬细胞瘤（PCI2）细胞作为神经细胞模型，利用水平轴回转器模拟微重力效应。回转72h后，对回转和对照组细胞进行一氧化氮合酶和硝基酪氨酸的免疫细胞化学染色分析，同时采用硝酸盐还原酶偶联法测定回转PC12细胞的一氧化氮（NO）水平，竞争性ELISA方法定量检测细胞硝基酪氨酸的水平。结果回转后PC12细胞诱导型一氧化氮合酶（iNOS）和硝基酪氨酸免疫细胞化学染色均增强。回转后PCI2细胞NO水平升高（P〈0．01），蛋白质酪氨酸硝基化程度显著增加（P〈0．01）。结论模拟失重可诱导PC12细胞NO的合成，增加蛋白质氧化损伤程度。     

间断性头高位45°对模拟失重兔股静脉顺应性的影响

目的观察间断性头高位45°锻炼对模拟失重兔股静脉应力-应变关系的影响。方法采用兔头低位-20°倾斜的方法模拟失重。24只雄性健康兔,随机分为对照组、模拟失重21d组(HDT)和每天2h头高位45°对抗组(HUT),每组8只。实验21d后测试离体股静脉轴向和环向应力-应变关系的变化。结果在相同应力下,模拟失重组兔股静脉环向加、卸载形变较对照组均显著增加(P<0·05或P<0·01),而轴向加、卸载形变较对照组均无明显变化。对抗组与模拟失重组相比,在同等应力情况下,环向形变明显减小(P<0·05或P<0·01),轴向形变无明显变化。对抗组与对照组相比,轴向及环向形变均无显著差异。结论21d模拟失重可引起兔股静脉顺应性显著增加,每天2h头高位45°锻炼可部分对抗模拟失重所引起的股静脉顺应性的增加。     

头低位卧床(OHDT,-6°)对人尿儿茶酚胺分泌昼夜节律的影响

我们利用头低位(-6°)卧床作为模拟失重模型进行了6名男性志愿者卧床一周的实验,目的是分析卧床条件下人尿肾上腺素(E)、去甲肾上腺素(NE)昼夜节律特点以及心血管功能的反应。结果表明,卧床期E、NE 及E+NE 昼夜节律的水平和幅度显著降低;儿茶酚胺(CA)各成份的相位发生了内部解离,上述变化在卧床后5天内皆恢复正常。说明头低位卧床能影响人尿CA 的昼夜节律。