15d-6°头低位卧床对女性抑制功能的影响

目的 探讨-6°头低位卧床模拟失重对女性抑制能力的影响.方法 志愿者分为接受头低位卧床实验的卧床组和不参加卧床的对照组,采用数字Stroop任务测试两组志愿者在卧床实验前5天、卧床第5天、卧床第10天以及卧床后第5天的抑制能力,并采用贝克焦虑量表和Beek抑郁量表同步记录各测试时间点志愿者的抑郁和焦虑情绪.结果 卧床第...     

人在头低位卧床时拟交感药物引起的心血管反应：食物中钠的作用

人在头低位卧床时拟交感药物引起的心血管反应：食物中钠的作用心血管系统对微重力的适应过程中表现出交感肾上腺功能的变化和心血管功能失调。心血管功能的失调将引起航天员飞行后立位耐力降低。本实验的目的是比较吃正常食物和含高钠食物的两组被试者在卧床前、中、后服...     

15d-6°头低位卧床女性志愿者主要膳食营养素摄人分析

目的 了解女性志愿者15 d头低位卧床实验期间主要膳食营养素摄取情况.方法 采用称重和化学分析相结合的方法对22名志愿者15 d卧床前期和后期进行2次膳食调查,每次连续3 d.结果 从三大营养素供热构成来看,女性志愿者整个卧床期间蛋白质摄入偏高,碳水化合物摄入偏低,脂肪摄入基本满足要求;头低位卧床对照组((20N)的能...     

15d-6°头低位卧床女性志愿者护理初探

对22名参加15 d头低位卧床的女性大学生志愿者进行了卧床期间的护理观察,通过分析头低位卧床期间志愿者出现的症状和体征,采用了以通便、排尿和心理疏导为主的护理手段,提出了重点以维持人体代谢功能处于稳态的卧床实验护理理念.     

运动锻炼对30d-6°头低位卧床所致承重骨丢失的影响

目的观察下肢肌力锻炼和功率车锻炼对30 d-6°头低位卧床引起骨丢失的防护效果,为筛选航天员暴露于空间微重力环境下运动锻炼方法提供参考。方法15名男性青年受试者分为卧床对照组、下肢肌力锻炼组和功率车锻炼组,每组5人,在30 d-6°头低位卧床期间,两个运动锻炼组共进行了25 d(次)的运动锻炼,下肢肌力组每天锻炼16~18 min,功率车组每天锻炼30 min。分别于卧床前和起床后测量了全身骨密度(BMD QDR-4500/W Hologic)和腰椎骨小梁比值(CTPhilips-Mx-8000)。结果与卧床前相比,对照组卧床以后全身骨矿含量显著下降(P0.05)、左髋总骨密度和右髋大转子骨密度显著下降(P0.01),第2~4腰椎骨小梁比值显著下降(P0.05),功率车锻炼组虽然全身骨密度显著增加,但是第3~4腰椎骨密度却显著下降(P0.05),下肢肌力锻炼组全身和腰椎及髋部等承重部位的骨矿含量和骨密度均无明显下降。结论30 d-6°头低位卧床可引起腰椎和髋骨等承重部位明显的骨丢失,功率车锻炼方法不能改善腰椎部位的骨丢失,下肢肌力锻炼方法对于维持全身和承重部位的骨密度具有明显的防护效果,该结果将对我国载人航天飞行失重对抗措施方案的制定提供重要的参考。     

模拟微重力期间前臂血管阻力的压力感觉器反射调节功能的变化

模拟微重力期间前臂血管阻力的压力感觉器反射调节功能的变化微重力所引起的航天员血浆容量的减少，会影响到心肺压力感受器的调节功能，本实验的目的是观察７ｄ头低位卧床对心肺压力感受器反射功能的影响：被试考１１名，－６°头低位卧床７ｄ，实验前及卧床第７ｄ测安静...     

失重/模拟失重对眼结构和视功能影响的研究进展

失重作为一种最主要的太空环境因素,对航天员眼结构和视功能会产生不同程度的影响,不仅涉及航天员自身的眼健康,而且关系到对航天仪器操作的准确性和及时性.综述了模拟失重对动物眼结构和视功能的影响,头低位卧床试验及在轨飞行对人体眼结构和视功能等方面的影响,阐述了失重对眼结构的影响,包括视网膜神经节细胞、血管内皮细胞的凋亡,脉络...     

15d-6°头低位卧床女性腰椎X线影像变化及防护效果

目的 研究下体负压/自行车功量计锻炼对15 d头低位卧床女性腰椎功能失调的防护作用.方法 对22名女性志愿者分为对照组(CON,n=8)、下体负压锻炼组(LBNP,n=7)、下体负压联合自行车功量计锻炼组(LBNP+ERGO,n=7),在卧床前和卧床后第4天,采用X线对脊柱状态进行了检查.分别测量并比较卧床前后腰椎总长...     

15d-6°头低位卧床对女性个体再认记忆、前瞻记忆的影响

目的 考察女性受试者在15 d-6°头低位卧床模拟失重条件下再认记忆和前瞻记忆的变化趋势.方法 22名女性受试者进行-6°头低位卧床.在卧床前5 d、卧床期间(第5,10天)及卧床后(第5天)同步考察卧床组和对照组的再认记忆、基于事件的前瞻记忆、基于时间的前瞻记忆能力,对受试者所采取的策略进行记录.结果 卧床组比对照组...     

45天-6°头低位卧床对视觉搜索能力的影响

目的 监测健康成年男性在45 d-6°头低位卧床实验过程中视觉注意搜索能力是否会受到影响.方法 16名男性健康成年受试者进行45 d-6°头低位卧床以模拟失重状态.在卧床前12天、卧床期间(第10,20,30,40天)以及卧床之后第13天进行视觉注意搜索实验.实验一是考察pop-out的被动注意的并行搜索实验,实验二则是考察需要主动注意的串行搜索实验.结果 实验一发现受试者的反应时和正确率在几次测试中没有发生显著变化;而实验二受试者的行为表现在测试中逐渐提高,说明发生了知觉学习,其学习过程先快后慢而且逐渐趋于稳定.结论 45 d-6°头低位卧床模拟失重条件下,人的基本视觉搜索能力并没有随着卧床时间的延长而显著变差,视知觉学习能力也仍然存在.     

Bed rest affects ventricular and arterial elastances in monkeys: implications for humans

METHODS: Experimental data were obtained from five chronically instrumented rhesus monkeys exposed to 96 h of 10 degrees head-down bed rest (HDBR) and another 96 h of 80 degrees upright control separated by 9 d of ambulatory recovery in a counter-balanced, crossover experiment design to test the hypotheses that: 1) headward and footward fluid shifts would increase systemic arterial (Eart) and left ventricular end-systolic (Ees) elastances; and 2) changes in Eart and Ees would be related in magnitude and direction. Ees and Eart were calculated from measurements taken during five observation periods for initial 2-h and 4-d exposures to HDBR that produced headward volume shifts, and acute exposure to graded levels of lower body negative pressure (LBNP) designed to produce orthostatic volume shifts. RESULTS: There was no effect of HDBR on Ees and Eart for any observation period (initial 2-h, 4-d, or LBNP). Eart increased in a similar pattern during the 4-d exposure to both control and HDBR. Ees increased with increasing LBNP levels for both control and HDBR while Eart remained unchanged. CONCLUSION: Our data are consistent with the notion that elevated Eart may represent an adaptation to physical inactivity that is associated with cardiovascular deconditioning.     

30d头低位卧床对男性牙龈色彩的影响

目的研究头低位卧床模拟失重对健康人牙龈颜色的影响。方法采用﹣6°头低位卧床模拟失重,在5个时间点:卧床前第3天(HDBR-3)、卧床第10天(HDBR 10)、卧床第20天(HDBR 20)、卧床第30天(HDBR 30)和恢复期第3天(HDBR+3)检测游离龈和附着龈的色彩。结果与卧床前相比,男性志愿者牙龈游离龈、附着龈的L*值在卧床第20天、30天显著升高(P<0.05),在卧床第10天、恢复期第3天无显著性差异;游离龈和附着龈的a*和b*值在卧床第20天、30天和恢复期第3天非常显著升高(P<0.01),在卧床第10天无显著性差异。结论失重环境可使人体游离龈、附着龈发生炎症反应。为降低失重对人体口腔软组织的影响,在航天员的日常训练和航天实验过程中应加强口腔组织的卫生防护。     

30d-6°头低位卧床对腰椎和椎旁肌肉面积的影响

目的 观察30 d-6°头低位卧床实验后志愿者腰椎高度、腰椎间隙中矢状位面积、腰椎前凸角度以及椎旁肌肉横切面积的变化.方法 14名健康男性参加30 d卧床模拟失重实验.于卧床前1天、卧床第30天分别进行腰椎核磁检测,同时测量人体腰椎高度、腰椎间隙中矢状位面积、腰椎前凸角度以及椎旁肌肉横切面积.结果 30 d卧床实验后志...     

Orthostatic tolerance and hormonal changes in women during 120 days of head-down bed rest

BACKGROUND: Women will be included as mission specialists in the upcoming International Space Station program. This paper describes the changes in volume-regulating hormones and determines the degree of degradation in orthostatic tolerance in a group of women after 120 d of bed rest. The aim of this study was to test a countermeasure program to be used by women during long-duration spaceflights. METHODS: For 120 d of -6 degrees head-down bed rest (HDBR), eight healthy women were assigned either to a no-countermeasure (No-CM, n = 4), or to a countermeasure (CM, n = 4) group. In the countermeasure group, exercise began after 2 wk, pharmacological agents were given during the 1st and 3rd mo, and the "Centaur" suit was worn on the last day of bed rest and during the day time for several days after bed rest. Diet supplements were taken during the 1st and 4th mo of HDBR. Tilt tests were run before and after HDBR. RESULTS: After the HDBR, none of the CM subjects, had pre-syncopal or syncopal symptoms during tilt tests: BP was well maintained in the CM group, while heart rate and BP changed in the No-CM group. In plasma, atrial natriuretic peptide (ANP) increased in both groups and remained high throughout HDBR, while aldosterone increased and remained elevated in the No-CM group. Natriuresis was decreased during HDBR. CONCLUSION: The CM protocols used during this study were efficient and prevented orthostatic intolerance for the four CM subjects. It would be necessary to obtain more data regarding this set of CM protocols on female subjects to lead to statistical and formal conclusions.     

Vasomotor sympathetic nerve activity in men during bed rest and on orthostasis after bed rest

BACKGROUND: Alterations in autonomic function are commonly seen during and after spaceflight, and its ground-based analog, 6 degrees head-down bed rest (HDBR). They may include peripheral vascular regulation, but vasomotor sympathetic efferent nerve discharges to peripheral vasculatures have not been examined. The aim of our study was to examine changes in vasomotor sympathetic nerve activity during HDBR and under orthostasis after HDBR. METHODS: We performed 6 d of HDBR on six male subjects, and measured muscle sympathetic nerve activity (MSNA) together with plasma norepinephrine concentrations in the supine position before HDBR and in 6 degrees head-down position on the sixth day (HDBR6) of HDBR. We also measured MSNA in head-up tilt (HUT) test before and after HDBR. RESULTS: On HDBR6, MSNA burst rate was the same (17+/-4 bursts x min(-1)) as that in supine position before HDBR (15+/-2 bursts min(-1)), but plasma norepinephrine concentrations were decreased to 1.14+/-0.10 pmol x ml(-1) compared with the supine value before HDBR (1.56+/-0.20 pmol x ml(-1), p<0.05). After HDBR, supine MSNA burst rate significantly increased by 58% to 24+/-4 bursts x min(-1). MSNA increment in response to HUT was similar between before (34+/-3 bursts min(-1) x sin HUT(-1)) and after (40+/-6 bursts x min(-1) x sin HUT(-1)) HDBR. CONCLUSIONS: Our findings suggest that: a) the relationship between MSNA and plasma norepinephrine concentrations was altered on the sixth day during HDBR; b) the vasomotor sympathetic nerve activity was enhanced after HDBR; and c) the augmentation of vasomotor sympathetic outflow to muscles under orthostasis was preserved after HDBR.     

Adaptations to a 7-day head-down bed rest with thigh cuffs

PURPOSE: Thigh cuffs were two elastic strips fixed at the upper part of each thigh, which limits the shift of fluid from the legs into the cardio-thoracic region. The purpose of this study was to examine the effects of thigh cuffs on hormonal and plasma volume responses and orthostatic tolerance during a 7-day head-down bed rest (HDBR). METHODS: Orthostatic tolerance, plasma volume, total body water, blood volume-regulating hormones, and hydro-electrolyte responses were measured in eight healthy men (age range, 25-40 yr), using thigh cuffs 10 h daily during 7 d of -6 degrees HDBR. RESULTS: Thigh cuffs worn during HDBR attenuated the decrease in plasma volume observed after HDBR (thigh cuffs: -5.85 +/- 0.95% vs control: -9.09 +/- 0.82%, P < or = 0.05). During this experiment, there was no significant change in total body water. Thus, the hypovolemia did not result from a loss of water but from a fluid shift from the blood compartment into the interstitial and/or intracellular compartment. Hormonal responses during HDBR and stand test were not modified by the thigh cuffs. Thigh cuffs had no significant effect on the clinical symptoms of orthostatic intolerance after HDBR. CONCLUSIONS: Thigh cuffs worn during HDBR blunted the decrease in plasma volume but did not reduce orthostatic intolerance; thus, they are not a completely effective countermeasure. Furthermore, hypovolemia seems to be necessary but not sufficient to induce orthostatic intolerance after HDBR.     

模拟失重对人脑工作记忆的影响:系列功能磁共振成像研究

目的 采用功能性磁共振技术研究微重力环境对工作记忆的影响. 方法 9名健康男性青年头低位卧床4周.卧床前、卧床1周时和卧床4周后各对其进行1次倒数2项工作记忆任务的功能磁共振成像扫描. 结果 模拟失重前,工作记忆任务激活的脑区有双侧额叶(BA46/9、47、6)、前扣带回(BA32)、双侧顶叶(BA7)、双侧枕叶(19/18)和左侧丘脑.模拟失重1周时,激活脑区的范围和信号强度变化显著.模拟失重4周后,激活脑区与卧床前趋于相似. 结论 ①模拟失重状态时,人脑工作记忆功能状态有明显的变化,主要表现为功能脑区激活范围和部位的变化;②模拟失重环境对工作记忆信息的被动贮存影响不大,但对信息的主动复述维持及中央执行系统的信息操作功能有明显、可逆的影响;③失重1周时,人脑激活区变化显著.失重4周时,人脑已经开始逐步适应,但未正常化.     

低氧、气功对抗模拟失重后立位中心脏节律变化的观察

目的探讨新的对抗失重措施。方法１５名、年龄１９～２２岁的健康男性青年为被试者。头低位－６°卧床（－６°ＨＤＢＲ）模拟失重,持续２１ｄ。实验分对照组（单纯卧床）、低氧组（卧床＋低氧）和气功组（卧床＋气功）。低氧组卧床期间每人每天吸两次低氧,每次２０ｍｉｎ。气功组卧床中每天练功三次,每次４５ｍｉｎ。三组卧床前、后进行２０ｍｉｎ＋７５°的立位实验。结果三组被试者在卧床前立位中的心电图未发生明显变化,心律正常。卧床２１ｄ后立位实验中对照组２人出现房性和窦性心律紊乱;气功组２人出现结性心律紊乱。低氧组所有人均未发生心律紊乱。结论低氧对抗卧床后立位耐立降低效果较好。     

模拟失重条件下长时间脑力负荷始末前额区脑电多尺度墒的变化分析

目的 观察头低位卧床模拟失重期间脑电信号复杂度的变化,研究脑电信号多尺度熵与脑疲劳的关系.方法 8名健康男性志愿者以-15°头低位卧床(HDBR)为模拟失重,+15°头高位卧床(HUBR)为对照,志愿者静息30 min后进行2h内容为1-back图片记忆匹配VDT作业.结果 实验初HDBR条件下志愿者前额区脑电多尺度熵...     

45d-6°头低位卧床对人体运动心肺功能的影响及红景天的防护作用

目的明确45 d-6°头低位卧床(head-down bed rest,HDBR)模拟失重效应对运动心肺功能的影响及红景天的防护作用。方法 16名健康成年男性志愿者,随机分为对照组(8人)和中药组(8人),中药组和对照组在45 d卧床期间,每天分别服用红益胶囊和安慰剂。在卧床实验前、中、后分别进行人体运动心肺功能和运动心电测量。结果与卧床前相比,1)卧床45 d对照组最大耗氧量显著降低(-18.26%;P0.01),中药组最大耗氧量无显著差异(-10.04%;P0.05)。2)对照组最大公斤耗氧量在卧床30 d、45 d和卧床后10 d均较卧床前显著下降(P0.01),而中药组下降均不明显(P0.05)。3)卧床期间对照组和中药组的最大心率均无显著变化,但在卧床后10 d,对照组最大心率明显下降(P0.05),中药组无明显改变(P0.05)。结论 45 d-6°头低位卧床引起人体运动心肺功能明显下降,中药红益胶囊可有效对抗头低位卧床模拟失重效应的人体运动心肺功能下降。