回转器模拟失重对人胃黏膜HFE-145细胞形态和生物学特征的影响

目的探讨模拟失重对人胃黏膜上皮HFE-145细胞形态、增殖、周期和凋亡的影响.方法采用回转器模拟失重,用图像分析系统软件分析HE染色后人胃黏膜上皮HFE-145细胞形态的改变,用免疫组化法观察增殖细胞核抗原（PCNA）表达的变化,用流式细胞仪测定细胞周期,并用TUNEL法检测细胞凋亡.结果回转组HFE-145细胞在模拟失重12 h时的面积较对照组增大（P＜0.01）,其余时间段细胞的面积与对照组无明显差异;其长短径之比在各时间段与对照组均无明显差异.与正常对照组相比,回转组HFE-145细胞24 h、36 h、48 h及72 h的PCNA抗体阳性细胞的比率无明显差异,12 h回转组PCNA抗体阳性细胞比率明显减少（P＜0.05）.24 h、36 h、48 h和72 h回转组HFE-145细胞的细胞周期分布与对照组相比无明显差异,12 h回转组G0＋G1期细胞比例较对照组明显增多（P＜0.05）,S＋G2＋M期细胞之和较对照组显著减少（P＜0.05）.24 h、36h、48 h和72 h回转组HFE-145细胞凋亡的比例与对照组相比无明显差异,12 h回转组细胞凋亡比例较对照组明显增多（P＜0.05）.结论回转器模拟失重使胃黏膜上皮HFE-145细胞在12 h时形态发生了变化,出现细胞周期阻滞、增殖抑制和凋亡增加.     

血管紧张素Ⅱ 1型受体阻断对模拟失重大鼠动脉血管反应性的影响

目的探讨血管紧张素Ⅱ1型受体(AT1)阻断对模拟失重大鼠动脉血管收缩以及舒张反应性的影响。方法32只SD大鼠随机等分为对照组(CON),模拟失重组(SUS),对照 氯沙坦(losartan)组(CON L),模拟失重 氯沙坦组(SUS L),采用尾部悬吊大鼠模型模拟失重的生理影响,其中CON L组以及SUS L按照30mg.kg-1.day-1的剂量给予氯沙坦干预。3周后,采用离体动脉血管环技术观察大脑基底动脉和股动脉血管环对氯化钾(KCl)、5-羟色胺(5-HT)、苯肾上腺素(PE)、乙酰胆碱(Ach)、硝普钠(SNP)的反应性,以判断动脉血管的收缩以及舒张反应性的变化。结果SUS组大鼠基底动脉对KCl和5-羟色胺收缩最大反应性增强(KCl:F=14.018,P<0.01;5-HT:F=27.435,P<0.01),Ach内皮依赖性舒张最大反应性下降(F=49.045,P<0.01),股动脉对KCl以及苯肾上腺素收缩反应性与对Ach的舒张反应性均下降(KCl:F=19.244,P<0.01;PE:F=19.037,P<0.01;Ach:F=44.973,P<0.01)。SUS L组大鼠基底动脉收缩高反应性以及Ach舒张低反应性均得到改善(收缩:F=14.018,P<0.01;舒张:F=49.045,P<0.01),而氯沙坦干预对股动脉收缩以及舒张反应性并没有影响。结论局部肾素-血管紧张素系统(L-RAS)参与了模拟失重大鼠动脉血管功能重建过程,前半身与后半身动脉血管组织L-RAS差异性激活可能是模拟失重所导致的动脉血管功能分化性改变的重要因素之一。     

空间环境对黑色素瘤细胞基因表达谱的影响

目的探讨空间环境对黑色素瘤B16细胞基因表达谱的影响。方法利用“细胞在常温条件下长期存活装置”将B16细胞进行无源搭载。返地后常规培养，以常规培养的野生型B16细胞及地面装置组作为对照，甲基噻唑基四唑法测定细胞生长曲线，基因芯片分析细胞18240个基因的差异表达。结果搭载细胞返地培养后，与对照组细胞相比，生长速率差异没有显著性意义。与常规培养的对照相比，地面装置组细胞及空间组细胞分别有61及156个基因发生明显改变；其中35个基因为地面装置组及空间组细胞二者共同与常规对照组细胞差异表达，30个基因为空间培养细胞与地面装置组细胞之间差异表达；差异表达的基因涉及Wnt及Ca^2＋等信号传导途径。结论空间环境作用后，B16肿瘤细胞基因表达改变，一些信号传导途径及能量代谢表现为对空间环境较为敏感。     

模拟失重可能降低大鼠心肌肌浆网功能

采用离体乳头肌灌流、改变刺激频率和快速冷却等干预实验，探讨模拟失重４周大鼠心肌收缩性能降低的可能机理。结果表明：模拟失重大鼠乳头肌：（１）等长收缩达到张力峰值的时间明显延长；（２）细胞外Ｃａ＋浓度为８．０ｍｍｏｌ／Ｌ时，增加刺激频率，张力随之降低；（３）电刺激张力与停止电刺激ｌｓ的冷挛缩张力明显降低。这些均提示，模拟失重４周可能使心肌肌浆网Ｃａ＋＋摄取与释放速率降低。     

21天头低位卧床期间脑血流的变化及其与立位耐力的关系

目的建立３周头低位倾斜（ＨＤＴ）－６°人体实验模型，观察卧床模拟失重期间脑血流变化及其与立位耐力的关系。方法６名健康男性志愿者进行了２１天ＨＤＴ－６°卧床试验。受试者年龄２３．８±６．１岁。ＨＤＴ前、ＨＤＴ第１０天及卧床结束时进行了３次立位耐力检查。ＨＤＴ前、ＨＤＴ第３天、第１０天、第２１天用ＫＹＥＮＧ－Ⅰ导纳式双侧脑血流自动检测仪测量脑血流量。结果卧床第１０天和卧床结束时，受试者立位耐力平均立位时间比卧床前显著降低（Ｐ＜０．０５）。卧床期间，左右侧大脑血流主峰高度和Ⅰ相面积较卧床前显著降低（Ｐ＜０．０５或Ｐ＜０．０１）；卧床第３天和第２１天的左侧大脑阻力指数较卧床前显著增高（Ｐ＜０．０５），卧床第１０天、第２１天的左侧大脑血液流入时间较卧床前显著延长（Ｐ＜０．０５），卧床期间左侧大脑血液流入速度比卧床前显著降低（Ｐ＜０．０５或Ｐ＜０．０１）；卧床期间受试者左侧大脑Ⅰ相面积、左侧主峰高度、左侧大脑血液流入速度均和立位耐力时间呈显著正相关（Ｐ＜０．０１或Ｐ＜０．０５）。结论２１天头低位卧床使立位耐力显著降低；ＨＤＴ卧床期间，脑血管阻力增加，脑血流量减少，可能是导致立位耐力降低的原因之一。     

模拟失重大鼠肺组织肺炎链球菌感染的病理改变

目的 建立模拟失重条件下大鼠细菌性肺炎的动物模型,观察模拟失重对大鼠肺组织肺炎链球菌感染的影响. 方法 36只雄性Wistar大鼠按随机数字表法分为失重感染（weightless and infection,WI）组、失重对照（weightlessness and control,WC）组和1G重力感染（1 G gravity and infection,GI）组,每组12只.实验第8天（注入细菌后的第6天）处死各组大鼠,检测血常规、C-反应蛋白（C-reactive protein,CRP）及CD4 T淋巴细胞和CD8 T淋巴细胞的比值（CD4＋/CD8＋）.观察大鼠肺组织病理变化. 结果 各组大鼠白细胞计数差异无统计学意义,中性粒细胞（neutrophils,NEU）计数及NEU比值差异有统计学意义（F=6.12、4.23,P＜0.01、＜0.05）,其中WI组最高;3组大鼠的CRP差异有统计学意义（F=19.49,P＜0.01）,其中WI组最高,WC组最低;各组大鼠外周血中CD4＋/CD8＋差异无统计学意义.WI组肺组织病理改变最严重,炎症反应较重;GI组可见部分肺组织病理改变,炎症反应程度较轻;WC组肺组织病理改变和炎症反应均最轻. 结论 模拟失重（微重力）状态下大鼠机体免疫功能降低,肺炎链球菌肺部感染的病理改变严重,炎症反应较重.     

模拟飞船舱内中长期失重及噪声复合因素对大鼠听器官的影响

目的　探讨模拟飞船舱内2～8周的中长期失重及噪声复合因素对大鼠脑干诱发电位和耳蜗结构的影响。方法　健康成年大鼠随机分成雄性实验及对照组、雌性实验及对照组。实验组暴露于模拟失重及稳态噪声环境中,实验结束前给予脉冲噪声暴露;对照组不施加因素。分别于实验前、实验第2、4、8周及脉冲噪声暴露后检测双侧听性脑干反应阈值（ABR）,并行扫描电镜观察。结果　两实验组内脉冲噪声暴露后ABR阈值明显增高（P 均＜0.05）;实验后2、4周ABR阈值雌性实验组均较雄性实验组低（P 均＜0.05）,扫描电镜观察发现内外毛细胞缺失,大片倒伏,随着复合因素作用时间延长耳蜗毛细胞病理性改变加重。结论　中长期失重噪声复合因素可造成大鼠听功能损害,且脉冲噪声比稳态噪声更明显;损害存在性别差异;大鼠耳蜗毛细胞病理性改变随复合因素时间延长而加重。     

模拟失重对恒河猴腰椎运动单元生物力学的影响

BACKGROUND: It is generally believed that the spine will be extended, and vertebral muscle atrophy, bone loss of vertebral body, increased height and area of intervertebral disc, changes of composition of intervertebral disc will occur in the condition of weightlessness. These are likely to be the cause of high incidence of low back pain.     

Metabolic and Biomechanical Effects of Velocity and Weight Support Using a Lower-Body Positive Pressure Device During Walking

Grabowski AM. Metabolic and biomechanical effects of velocity and weight support using a lower-body positive pressure device during walking.

Objectives

To determine how changes in velocity and weight support affect metabolic power and ground reaction forces (GRFs) during walking using a lower-body positive pressure (LBPP) device. To find specific velocity and weight combinations that require similar aerobic demands but different peak GRFs.

Design

Repeated measures.

Setting

University research laboratory.

Participants

Healthy volunteer subjects (N=10).

Interventions

Subjects walked 1.00, 1.25, and 1.50m/s on a force-measuring treadmill at normal weight (1.0 body weight [BW]) and at several fractions of BW (.25, .50, .75, .85 BW). The treadmill was enclosed within an LBPP apparatus that supported BW.

Main Outcome Measures

Metabolic power, GRFs, and stride kinematics.

Results

At faster velocities, peak GRFs and metabolic demands were greater. In contrast, walking at lower fractions of BW attenuated peak GRFs and reduced metabolic demand compared with normal weight walking. Many combinations of velocity and BW resulted in similar aerobic demands, yet walking faster with weight support lowered peak GRFs compared with normal weight walking.

Conclusions

Manipulating velocity and weight using an LBPP device during treadmill walking can reduce force yet maintain cardiorespiratory demand. Thus, LBPP treadmill training devices could be highly effective for rehabilitation after orthopedic injury and/or orthopedic procedures.     

Physical inactivity and cognitive functioning: results from bed rest studies

In addition to multiple health benefits, participation in physical activity can enhance cognitive functioning. Less clear is how reducing physical activity levels affects cognition, an issue potentially addressed by bed rest studies having included cognitive tests. Detailed and reviewed here are 17 such studies, featuring 251 subjects, bed rest for 7–70 days, and tests of cognition ranging from reaction time to executive functions. The reported effects of bed rest on cognitive performance vary considerably, from a generally expected worsening to an improvement. Practice effects could be implicated in the performance improvements, and reports of worsening are often of limited interpretability or the results were not replicated. Any cognitive effects of bed rest thus remain to be established. Detrimental effects could influence the in-progress plans for human spaceflights to Mars (simulated by bed rest), and have implications for medical conditions promoting inactivity and lifestyles that are largely sedentary.