21天头低位卧床期间颅底动脉血流变化及下体负压的对抗作用

目的 观察21d头低位卧床期间颅底动脉血流动力学的变化及下体负压的对抗作用效果。方法 12名健康男性志愿者，随机分为对照组和下体负压组，每组6人，进行21d头低位倾斜卧床。对照组在卧床期间不做任何处理，下体负压组在卧床的经1周以及最后1周，每天进行1h-30mmHg的下体负压锻炼。利用经颅超声多普勒（TCD）测量头低位卧床9HDT）前（坐位），HDT开始时，第1，3，7，10，21天双侧大脑前，中，后动脉的血流动力学指标。结果 卧床期间，对照组右侧中动脉（MCA）的收缩期峰值血流速度Vs较卧床前（preHDT)及卧床开始时显著降低，左侧MCAVs在卧床开始时较卧床前显著增加，卧床第3天又较开始时显著降低。在卧床期间，下体负压组右侧MCA血流速度Vs,Vd，左侧后动脉（PCA）血流速度Vd较卧床开始时显著降低，卧床第7天右侧MCA血流速度Vd较卧床前显著降低。结论 21d头低位卧床期间双侧MCA的Vs显著降低，并有MCA的不对称变化，前，后各1周的下体负压锻炼不能改善MCA血流速度的降低。     

用气机升降理论探讨对失重的中医学认识及失重性肌萎缩的中医病机

随着航天事业的发展,太空环境对航天员身体造成的损害日益受到关注,其中失重是引起各种病症的最重要病因,而失重引起的肌肉萎缩是航天医学亟待解决的问题之一。虽中医古代文献中无“失重”、“失重性肌萎缩”等概念,但中医理论能宏观把握复杂疾病的病机特点,为防治失重性疾病,尤其失重性肌萎缩提供重要的理论参考。本文拟从气机升降理论的角度出发,从气血运行和脏腑功能变化探讨对失重的中医学认识以及形成失重性肌萎缩的中医病机,以期为中医理论在航天医学中的应用价值做出一些贡献。     

尾悬吊模拟失重对雌性大鼠生殖功能的影响

目的: 探讨模拟失重对雌性大鼠生殖功能的影响及其发生机制,为太空探索者的健康保护提供可借鉴的科学线索。方法: 利用尾部悬吊法建立模拟失重状态大鼠模型;选取Wistar雌性大鼠72只,随机均分为6组,3个实验组分别为:模拟失重7 d组、模拟失重14 d组和模拟失重21 d组;3个对照组是与模拟失重组相对应的自由活动组。应用酶联免疫吸附法(ELISA)检测血清中雌二醇(E₂)、卵泡刺激素(FSH)和黄体生成素(LH)水平;HE染色观察卵巢组织结构,特异性脂褐素染色观察卵巢组织衰老状况;逆转录定量PCR(qRT-PCR)技术检测细胞衰老相关分子端粒酶逆转录酶(TERT)、p53、p16、p21和P27的mRNA表达水平;免疫组织化学方法检测P53、P16、P21和P27的蛋白表达;随机取健康雄性大鼠分别与各组雌性大鼠合笼,比较生育仔鼠数量和存活率。结果: 与各对照组相比, 模拟失重7 d组、14 d组和21 d组大鼠血清中E₂下降,FSH和LH上升(P<0.05);大鼠卵巢组织卵泡数量明显减少,卵巢组织发生细胞衰老现象,细胞衰老相关分子TERT mRNA表达被抑制(P<0.05),衰老相关的细胞周期调控分子p53、p16、p21和p27在mRNA和蛋白水平表达均升高(P<0.05)。各模拟失重组雌性大鼠生育的仔鼠数量较相应的对照组明显减少(P<0.05),仔鼠存活率显著下降(P<0.01)。结论: 尾悬吊模拟失重导致雌性大鼠生殖功能下降,该现象与模拟失重诱导卵巢组织细胞衰老和下丘脑-垂体-卵巢轴内分泌功能紊乱相关。     

Physiological responses to body weight--supported treadmill exercise in healthy adults

Hoffman MD, Donaghe HE. Physiological responses to body weight–supported treadmill exercise in healthy adults.

Objective

To determine whether the relationships of heart rate, rating of perceived exertion (RPE), and ground reaction forces (GRFs) with oxygen consumption rate (V?o₂) during treadmill exercise are altered by partial body weight support (BWS) via lower-body positive pressure.

Design

Repeated-measures design.

Setting

Exercise physiology laboratory.

Participants

Healthy, active adults (N=12); mean age ± SD, 45.1±12.6 years.

Interventions

Not applicable.

Main Outcome Measures

V?o₂, heart rate, RPE, and GRFs were measured during walking and running at 3 levels (0%, 25%, 50%) of BWS. Before exercise, standing heart rate and blood pressure were measured under each BWS condition.

Results

Standing heart rates were 7 beats/min lower (P<.05) and systolic blood pressures were 10mmHg higher (P<.001) at 50% BWS compared with 0% BWS, but mean blood pressure while standing and the relationship of heart rate with V?o₂ during walking and running were not altered by BWS. While walking, the RPE at a V?o₂ of 10 mL · kg^–1 · min^–1 was statistically lower (P<.05) at 0% BWS compared with 25% and 50% BWS (mean values, 7 vs 8 points), but RPE was not different among conditions while running at a V?o₂ of 25 mL · kg^–1 · min^–1. Peak normal GRFs at specified V?o₂ levels and RPE values were reduced (P<.05) with increasing BWS for walking and running.

Conclusions

Because partial BWS does not alter the relationship of heart rate with V?o₂ during exercise and has minimal effect on the relationship of RPE with V?o₂, training heart rate and RPE values do not appear to require adjustment with partial BWS. Reduced GRFs at specified V?o₂ levels from partial BWS suggest that there are important clinical applications of this technology.     

模拟失重大鼠胰腺组织HSP70表达的变化

目的 研究模拟失重环境下大鼠胰腺组织HSP70表达的变化.方法 健康雄性Wistar 大鼠64只,采用尾悬吊法建立模拟失重动物模型.按完全随机法分为悬尾6、12 h及1、2、3、5、7d组和未悬尾对照组.应用免疫组化法、蛋白质印迹法和RT-PCR法检测各组大鼠胰腺组织HSP70蛋白和mRNA的表达.结果 免疫组化染色显示,对照组大鼠胰腺组织无HSP70蛋白表达,悬尾组大鼠胰腺组织均有HSP70蛋白表达,尤其是胰岛细胞的胞质和胞核在早期即深染.蛋白质印迹法结果显示,悬尾6、12 h及1、2d组大鼠胰腺组织HSP70蛋白持续高表达,分别为0.921±0.078、0.862±0.048、0.838±0.063、0.807±0.071,较对照组的0.693 ±0.055显著增加(P＜0.05);3、5、7d组的HSP70蛋白表达恢复到对照组水平.HSP70 mRNA表达在6h组即明显增加至0.881 ±0.013,然后逐渐回落,3d组降至0.694±0.027,5d组出现回升,达0.836±0.014,7d组又回落至0.674±0.013.结论 模拟失重使大鼠胰腺组织中HSP70蛋白和mRNA表达发生明显变化,早期过表达,后期恢复正常水平.     

压力指示剂的制备及质量控制

目的：制备显示义齿组织面压通点的新型压力指示剂并建立其质量控制方法。方法：以羊毛脂、白凡士林等为辅料制备新型压力指示剂,并考察其性状、涂展性、不易黏附黏膜程度。测定锥入度,采用干燥失重法测定其中的水分含量;进行耐热、耐寒、离心、长期试验等稳定性考察。结果：制备的新型压力指示剂为淡黄色、非透明、质地均匀的半固体制剂,具有良好的颜色遮盖度,涂展性好,不易黏附口腔黏膜且容易去除,锥入度平均值为173．50单位（RSD-2．22％,n=6）。水分回收率试验平均回收率为100．28％（RSD=O．608％,m=5）。样品平均水分含量为45．42％（RSD=0．337％,n=5）;耐热和耐寒试验未见油水分离;离心试验未见分层;长期试验未见酸败、异臭、变硬、油水分离、分层现象发生;其含量亦无变化。结论：新型压力指示剂具有良好的性能,制备工艺简单,稳定性良好,质量可控。     

颈动脉血流对头低位-15°反应的个体差异

观察了头低位-15°、90min卧床条件下头颈部血液循环的变化特点。被试者为14名健康男性青年（18～21岁）。用超声多普勒血流仪测量了被试者在水平卧位和头低位时的颈总动脉血流量血流速度和管径等。结果表明，头低位时颈动脉血流量的变化存在较大的个体差异。根据颈动脉血流量的变化特点将被试者分为适应组（9人）与不适应组（5人）。与水平卧位相比较，在头低位时适应组颈动脉血流速度明显减慢、颈动脉管径扩张、头颈部循环阻抗增加，从而使颈动脉血流量保持在水平卧位时对照值附近，说明通过自身调节头部血液循环达到一个新的平衡状态。而不适应组的颈动脉血流量较水平卧位时有较大增加。结果提示，通过观察头低位时的颈动脉血流速度、管径、流量以及循环阻抗的变化趋势，可以评价人体心血管系统对失重状态下体液从心脏以下区域向头部区域重新分布的适应能力。     

Changes in monocyte functions of astronauts

As part of the systematic evaluation of the innate immune system for long duration missions, this study focused on the antimicrobial functions of monocytes in astronauts participating in spaceflight. The study included four space shuttle missions and 25 astronauts. Nine non-astronauts served as controls. Blood specimens were collected 10 days before launch, within 3h after landing, and again 3 days after landing. The number of monocytes did not differ significantly over the interval sampled in both the astronaut or control groups. However, following 5-11 days of spaceflight, the astronauts' monocytes exhibited reductions in ability to engulf Escherichia coli, elicit an oxidative burst, and degranulate. The phagocytic index was significantly reduced following spaceflight when compared to control values. This reduction in phagocytosis was accompanied by changes in the expression of two surface markers involved in phagocytosis, CD32 and CD64. Levels of cortisol, epinephrine, and norepinephrine after spaceflight did not increase over preflight values.     

模拟载人飞船内微重力和噪声环境下大鼠耳蜗毛细胞的形态学变化

目的：观察模拟载人飞船中微重力和噪声环境下大鼠耳蜗毛细胞的形态学特点,探讨耳蜗三回（底回、中回和顶回）毛细胞的不同变化。方法： 选取32只雄性健康SD大鼠,随机分为空白组、失重组、噪声组和失重+噪声组4组,每组8只。失重组以持续尾吊法模拟微重力,噪声组以持续2周的（72±2） dB SPL的稳态噪声及之后的3次高达160 dB SPL的脉冲噪声模拟飞船内复合噪声环境,失重+噪声组同时给予模拟微重力和噪声环境,空白组不做任何处理,常规饲养2周。暴露后检测听性脑干反应（auditory brainstem response, ABR）阈值,处死大鼠即刻取耳蜗基底膜行免疫荧光及扫描电子显微镜（scanning electron microscope, SEM）观察。 结果： 给予模拟环境暴露后,各组大鼠ABR阈值升高,各实验组大鼠暴露前后ABR阈值差异均有统计学意义（P<0.05）。免疫荧光结果显示：失重组底回以内毛细胞缺失为主,中回可见毛细胞肿胀,顶回毛细胞杂乱不清。噪声组底回以外毛细胞缺失为主,多见于最外层毛细胞,中回毛细胞肿胀,顶回杂乱并有毛细胞的缺失。失重+噪声组底回核缺失较明显,主要存在最外层毛细胞,内毛细胞也存在较多缺失。中回和顶回缺失发生在最内层外毛细胞。电子显微镜观察发现失重组底回纤毛大片倒伏,偶有缺失,顶回和中回毛细胞纤毛无明显异常。噪声组底回纤毛大片倒伏伴缺失,顶回和中回均有缺失,其中顶回最为严重。失重+噪声组底回纤毛大片融合伴缺失,中回纤毛融合、倒伏并缺失,顶回内外毛细胞纤毛大量缺失。4组的损伤程度：失重+噪声组>噪声组>失重组>空白组;三回毛细胞损伤程度：底回>中回>顶回。 结论： 模拟载人飞船内微重力和噪声环境中暴露2周可致大鼠耳蜗形态学结构发生显著变化,尤以失重+噪声组变化最明显,三回毛细胞中以底回最重,顶回最轻。     

Effects of microgravity on interstitial muscle receptors affecting heart rate and blood pressure during static exercise

Summary Afferent nerve fibers from receptors situated in the interstitium of skeletal muscles can induce cardiovascular reflexes. It has been shown that these interstitial muscle receptors are also sensitive to the local state of hydration: increased heart rates and blood pressure values were seen during dynamic and static exercise after local dehydration on earth. Since weightlessness leads to a persisting fluid loss in the lower part of the body, we hypothesized that leg exercise in space would augment heart rate and blood pressure responses to a similar extent as during local, interstitial dehydration on earth. Initial measurements during weightlessness were obtained in one subject after 6 days of space flight. Heart rate and blood pressure responses to light static foot plantar flexion (18% of maximal voluntary contraction) were recorded in two sessions. To eliminate the influence of muscle perfusion, exercise was performed during a period of arterial occlusion obtained by means of pneumatic cuffs at mid-thigh level. Identical protocols were used in the pre- and postflight controls, which were performed both in the sitting posture and in a –90° tilted sitting posture assumed 30–40 min before arterial occlusion. During weightlessness the exercise responses of heart rate and systolic and diastolic blood pressure closely followed the tracings obtained with the tilted sitting posture on ground. The response amplitudes in these states of reduced lower limb volumes (about 20/min and 20 mmHg, respectively) exceeded the responses in the supine position by a factor of at least 2. Enhancement of cardiovascular reflexes following local fluid losses of skeletal muscles appears to be a general phenomenon that can also be seen during weightlessness.Abbreviations EMG Electromyogram - LBNP Lower body negative pressure - MVC Maximal voluntary contraction