Balance and gait analysis after 30 days -6 degrees bed rest: influence of lower-body negative-pressure sessions.

Five volunteers took part in -6 degrees head-down bed-rest experiments for 30 d. In the first experiment, three subjects underwent several sessions of lower-body negative-pressure (LBNP) per day, with two others serving as controls. In the second, the LBNP group of the first experiment became the control and vice versa. Two experimental protocols analyzed the bed-rest-induced modifications of balance and gait and the efficiency of LBNP in counteracting these modifications. A kymographic method allowed the measurement of walking parameters. Anteroposterior and lateral sways were successively studied with both a force platform (static condition) and a rocking platform (dynamic condition). The tests were performed 2 d before the bed-rest period, and over the 1st, 3rd and 4th days of the recovery period. When the subjects were controls, bed rest decreased step length, walking velocity, and balance stability. LBNP completely counteracted the bed-rest-induced modifications of gait and static balance and of dynamic balance for the lateral sway. As LBNP was ineffective in counteracting the modifications of the anteroposterior sway, dynamic balance deficiency was independent of the beneficial effect of LBNP on the decreased orthostatic tolerance induced by -6 degrees head-down bed rest. The results indicate that head-down bed rest, like spaceflight, induces certain sensorimotor changes involved in the decrease of gait and balance performance.     

卧床模拟失重状态的中医辨证初探

用中医辨证法对１５名卧床２１ｄ的受试者民出现的临床证象发生发展进行了辨证分型。结果表明：卧床２１ｄ出现了肾阴虚、阴虚阳亢、脾气虚、血瘀四种证型，其中卧床３ｄ时各证象都较重，随卧床时间延长肾阴虚、阴虚阳亢逐渐减轻，脾气虚、血瘀变化同３displaystatus     

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.     

Ventilatory and cardiovascular responses to hypercapnia after 20 days of head-down bed rest

INTRODUCTION: Few studies have attempted to investigate the influence of prolonged head-down bed rest (HDBR) on hypercapnic ventilatory chemosensitivity, and there are no data available regarding associated changes in arterial BP and heart rate (HR). The aim of this study was to clarify the influence of prolonged HDBR on ventilatory and cardiovascular responses to hypercapnia. METHODS: There were five healthy men who participated in this study. Resting ventilatory and cardiovascular responses to hypercapnia were measured by means of Read's CO2 rebreathing method 4 d before and on the 19th day of HDBR. Measured variables included systolic and diastolic BP (SBP and DBP, respectively), inspired minute ventilation (VI), and end-tidal partial pressure of CO2 (PETCO2). RESULTS: Ventilatory response to hyperoxic hypercapnia (deltaVI/ deltaPETCO2) decreased significantly on the 19th day of HDBR (1.42 +/- 0.65 to 0.90 +/- 0.41 L x min(-1) x torr(-1), p < 0.05). On the other hand, SBP, DBP, and HR responses (deltaSBP/deltaPETCO2, deltaDBP/deltaPETCO2, and deltaHR/deltaPETCO2) were unchanged. DISCUSSION: The results from this study suggest that prolonged HDBR leads to diminished central hypercapnic ventilatory chemosensitivity.     

21天头低位卧床对肺弥散功能的影响

目的　探讨 2 1d - 6°头低位卧床 (HDT - 6°)对肺弥散功能的影响 ,并对其变化的相关因素进行分析 ,为地面模拟失重及航天飞行医学监督提供有关医学参考。　方法　采用Vmax 2 2LV肺功能仪和 6 2 0 0肺功能仪 ,对 16名健康男性受试者卧床前、后及卧床不同时间反映肺弥散功能的指标 [弥散容量 (DLco)、弥散常数 (Kco)、肺泡容量 (VA) ]以及反映肺内气体分布的指标和肺血容量分别进行了测试。　结果　与卧床前平卧位相比 ,在卧床开始时 ,DLco、Kco均增加 ,从卧床的第 3天起至恢复期第 1天 ,DLco、Kco显著减少 ,恢复期第 3天尚未恢复至卧床前水平 ;头低位卧床期间VA显著减少。Kco在卧床中的变化趋势与DLco一致 ,但变化率高于DLco ,主要是由于头低位卧床期间VA、肺血容量的显著减少以及肺内吸入气的分布不均有关 ,同时肺泡 毛细血管膜的变化也是不容忽视的因素。　结论　头低位卧床肺弥散功能下降与肺毛细血管血量的减少、肺泡容量下降 ,以及通气血流分布不均和潜在性的肺间质水肿导致膜弥散下降有关 ,在头低位卧床模拟失重的医学监督应考虑肺弥散功能的变化。     

21天头低位(-6°)卧床对机体摄入营养状况和头发Zn、Ca、Fe、Cu含量的影响

目的探讨模拟失重对机体摄入营养状况和头发Ｚｎ、Ｃａ、Ｆｅ、Ｃｕ含量的影响。方法受试者－６°头低位卧床２１天,用称量法观察其营养素摄入量变化,记录卧床第１天、１１天和第２１天的体重、尿量和上臂围,同时收集受试者头发,用原子火焰吸收分光光度法测定头发Ｚｎ、Ｃａ、Ｆｅ、Ｃｕ元素的含量。结果膳食Ｚｎ、Ｃａ、Ｆｅ、Ｃｕ在模拟失重第２周降低,第３周后基本恢复正常。头发中的含量第１１天较第１天显著下降（Ｐ＜０．０１）,第２１天恢复原来水平。尿量增加,体重和上臂围无明显变化。结论模拟失重对机体摄入营养状况和头发Ｚｎ、Ｃａ、Ｆｅ、Ｃｕ含量有短期影响,经过适应期后可恢复到正常范围。     

振动锻炼和太空养心丸对60 d头低位卧床脑血流的影响

目的 通过观察和比较60 d头低位(HDT)卧床期间振动锻炼、中药太空养心丸对脑血流的影响,进一步明确不同对抗方式对失重不良影响的对抗效果. 方法 21名健康男性志愿者,随机分为对照组、振动组和中药组3组,每组7人.对照组仅-6°HDT卧床60 d,口服安慰剂;振动组和中药组在HDT卧床期间分别进行阻抗振动锻炼和口服太空养心丸.卧床前、卧床第30天、第60天测量右侧大脑中动脉的血流速度. 结果 对照组的收缩期血流速度(Vs)在卧床第30天较卧床前显著降低(t=3.44,P<0.05),并且在第60天进一步降低t=5.07,P<0.01);舒张期血流速度(Vd)、平均血流速度(Vm)在卧床第60天显著降低(t=2.61、7.20,P<0.05).振动组的Vs在卧床第30天显著降低(t=2.49,P<0.05),并且在卧床第60天进一步降低(t=3.49,P<0.01);中药组Vs、Vd和Vm有降低趋势,但未达显著水平. 结论 60d头低位卧床可引起大脑中动脉血流速度显著降低.卧床期间服用太空养心丸对改善脑血流有一定作用,而振动锻炼则对脑血流影响不大.     

Hypoxic ventilatory response changes of men and women 6 to 7 days after climbing from 2100 m to 4350 m altitude and after descent

To test the hypothesis that the changes in hypoxic ventilatory response (HVR) of men and women mountaineers on induction to HA by trekking is not influenced by gender, isocapnic HVR as DeltaV(E)/DeltaSa(O2) was studied in eight men and eight women mountaineering trainees initially at 2100 m, then during 6 to 7 days of sojourn at 4350 m, and retested again on return to 2100 m. Results indicated that HVR at 2100 m increased significantly at 4350 m in both sexes, and the values reverted to baseline level within 4 to 5 days between leaving high altitude (4350 m) and restudy at 2100 m. No sex differences were observed at 2100- or at 4350-m altitude, indicating that men and women have a similar level of chemosensitive response as measured by HVR during induction to HA.     

冠状动脉支架植入前后及术后半年~(99)Tc~m-MIBI心肌断层显像定量分析

目的　通过对冠状动脉 (简称冠脉 )支架植入前后进行99Tcm 甲氧基异丁基异腈 (MIBI)心肌断层显像 ,以了解心肌灌注缺损程度、范围 ,判断SPECT在术前筛选、术后疗效评价、后期随访中的价值。方法　对 5 1例冠心病患者冠脉支架植入前后和 2 1例植入后半年 ,分别做静态和潘生丁负荷SPECT检查 ,定量分析心肌灌注缺损的部位、程度及范围。结果　术前 5 0例中 ,心肌血流灌注程度 >80 % (灌注缺损程度 <2 0 % )、灌注缺损范围 <2 0 % (比值越大 ,灌注缺损面积越大 )者为 0例 ;术后 1周有 7例灌注缺损程度、8例灌注缺损面积已完全正常 (14%和 16 % ) ;术前严重灌注缺损 <49%的 34例 (6 8% ) ,术后 1周 16例 (32 % )有改善 ;术前严重灌注缺损面积 >70 %的 35例 ,术后 1周 10例有改善 ,急性心肌梗死改善更明显。术前和术后 1周静态SPECT心肌灌注程度 38 0 5 %和 5 7 40 % ,改善 19 35 % ,术前和术后 1周静态SPECT心肌灌注缺损面积为 70 75 %和 5 5 91% ,改善 14 74% ,在术后 1周及半年心肌灌注缺损程度、灌注缺损面积均有明显改善 (P <0 0 0 1)。而术前、术后 1周及术后半年潘生丁负荷SPECT心肌灌注缺损程度、灌注缺损面积与术前、术后 1周及术后半年静息SPECT心肌灌注缺损程度、灌注缺损面积差异无显著性 (<3%     

—6°卧床对T淋巴细胞增殖功能和细胞因子产生的影响

探讨了短时间－６°卧床模拟失重对外周血Ｔ淋巴细胞受到多克隆刺激剂植物凝集素（ｐｈｙｔｏｈｅｍａｇｇｌｕｔｉｎｉｎ，ＰＨＡ）刺激后增殖能力和细胞因子产生的影响，结果表明：卧床模拟失重２ｄ后Ｔ淋巴细胞受到ＰＨＡ刺激后增殖明显下降；白细胞介素－２ｉｎｔｅｒｌｅｕｋｉｎ－２，ＩＬ－２）的活性呈下降趋势；白细胞介素－２受体（ｉｎｔｅｒｌｅｕｋｉｎ－２ｒｅｃｅｐｔｉｒ，ＩＬ－２Ｒ）的表达无明显改变，白细胞介素     

Effects of a 7-day head-down tilt (-6 degrees) on the dynamics of oxygen uptake and heart rate adjustment in upright exercise

Oxygen uptake (VO2) kinetics and heart rate (HR) kinetics were studied in six healthy male students before and on days 1,3 and 5 after a continuous 7-d antiorthostatic bedrest (-6 degrees). The exercise test protocol consisted of pseudorandom binary sequences (PRBS) of workload (W) performed on a bicycle ergometer in the upright position (20 W - 80 W, 15 bits, 30 s per bit; the sequence was repeated three times). Amplitude ratio and phase of the W-VO2 and W-HR relations were computed at six harmonic frequencies in the range 0.014 - 0.084 rad X s-1. After bedrest the VO2 kinetics was found to be impaired at the harmonic frequencies greater than 0.056 rad X s-1. Additionally, the mean heart rate during the PRBS cycles was increased (108 +/- 15 as compared to 92 +/- 10 min-1). There were no significant effects on HR kinetics and on the static W-VO2 relation. During an endurance training program both VO2 and HR changes were restored to the pre-bedrest levels. It is concluded that the impairment of VO2 kinetics can be attributed mainly to muscular factors.     

食管癌放射治疗前后的CT评价(附69例分析)

食管癌放疗疗效的评价十分重要（根治和姑息放疗），CT可显示病灶的大小，周围侵犯情况，淋巴结及肺内和胸膜转移情况。现对我院2001～2003年来行放疗的食管癌病人胸部CT资料进行分析，报道如下。     

Kinematic analyses of the 180 degrees standing turn: effects of age on strategies adopted by healthy young and older women

Standing turns are associated with an increased risk for falls and fall-related injuries in the elderly. The purpose of this study was to test the (null) hypothesis that age has no effect on the kinematics of the 180 degrees turn. Ten young and 10 older healthy women were asked to complete a series of 180 degrees turns in a standing posture after picking up a light bowl with both hands. Foot-ground reactions, insole pressures and body segment kinematics were recorded in 62 trials at 100 Hz. Turning strategies were analyzed for effects of both age and turn direction on linear and angular foot kinematics, as well as pelvic axial rotation. The older women (OW) used a preparatory stepping strategy more often (170%, p < 0.002), and employed a lower average pelvic rotation rate (21%, p < 0.011) than the younger controls. The minimum foot separation distance for OW was less in their non-preferred than in their preferred turn direction (29%, p < 0.038), thereby increasing their risk of foot-foot interference and falling when turning in their non-preferred direction. The older women were more variable in their turn execution, particularly in minimum foot separation distance (55%, p < 0.022) and the maximum rate of pelvic rotation (82%, p < 0.035). Despite the fact that these healthy older women were careful to employ a preparatory stepping strategy and slower average rotational velocities, they were also more variable in their turn execution than the young.     

儿童脑肿瘤的MRI表现(附60例分析)

目的：探讨儿童脑肿瘤的MRI特点，以期提高其诊断水平。方法：回顾分析经手术病理证实的60例儿童脑肿瘤MRI表现，并与病理结果进行对照。结果：60例中，发生于脑干17例(28．3％)，鞍内及鞍上区15例(25％)，小脑13例(21．6％)，幕上半球8例(13．3％)，间脑侧脑室、四脑室各2例，枕骨1例。大多数肿瘤在T1WI上表现为低信号、等信号或／和低信号，在T2WI上为不均匀高信号，增强扫描表现为均匀或不均匀强化。结论：胶质瘤是儿童期脑肿瘤最常见的肿瘤，脑干是其最常发生的部位，其次是颅咽管瘤，常发生于鞍内及鞍上区，小脑是儿童髓母细胞瘤常发生的部位。     

Acute effect of 3-(4-acetamido)-butyrril-lorazepam (DDS2700) on brain function assessed by PET at rest and during attentive tasks

The aim of this study was to assess, by positron emission tomography (PET), the effect on cerebral functional activity of a new lorazepam-gamma-aminobutyric acid (GABA) conjugate [3-(4-acetamido)-butyrril lorazepam (DDS2700)]. Ten healthy volunteers were studied by PET and [18F]fluoro-deoxy-D-glucose ([18F]FDG) under baseline conditions and following the administration of DDS2700. Regional cerebral blood flow (rCBF) was measured by PET and 15O-water in three additional participants while they performed attentive tasks, before and after drug administration. DDS2700 induced a decrease in the regional cerebral metabolic rate of glucose (rCMRglu) in the thalamus (-17%), cerebellum (-11%) and caudate nucleus (-8%). The observed effects on glucose metabolism were probably related to the subjective sedation and tiredness reported by the participants. During the attentive tasks, rCBF increased in frontal and temporal regions associated with attentional processing of auditory material. These circuits were no longer active after DDS2700 administration, while rCBF increased in cingulate cortex, occipitoparietal regions, pons and cerebellum. These drug-induced activations might be directly related to intervening sleepiness and to the consequent effort in keeping attention focused on the tasks. The effects of DDS2700 on glucose metabolism at rest, and on rCBF during activation conditions, indicate a drug action on cerebral networks involved in alertness, vigilance and attention maintenance. PET assessment by [18F]FDG and water may provide complementary information in pharmacodynamic studies.     

21 d-6°头低位卧床期间运动训练对动态姿态平衡的影响

目的探讨21 d-6°头低位卧床和卧床运动训练对动态姿态平衡和控制功能的影响. 方法 10名健康男性青年被试者分为卧床对照组和卧床训练组,每组5人,卧床期间训练组每天进行2次、每次30 min逐级增加负荷的头低位功率自行车训练;分别于卧床前和卧床后21 d进行了动态姿态平衡和双膝等速肌力的测试. 结果与卧床前相比,对照组动态本体感觉得分和运动控制适应能力明显降低,双膝相对峰力矩明显降低,同时伴有腘绳肌与股四头肌峰力矩屈/伸比值的明显增加;训练组动态本体感觉得分和运动控制适应能力明显高于对照组,而腘绳肌与股四头肌峰力矩屈/伸比值无明显改变. 结论 21 d-6°头低位卧床运动训练能够明显改善卧床后动态姿态平衡及其动态运动适应功能.     

头低位（—20℃）限制活动7d对兔庆大霉素药代动力学的影响

目的 探讨模拟失重条件下以血流量改变为经代动力学变化。方法 选择庆大霉素作为模型药物,采用头低位（－２０℃（兔限制活动为模拟失重动物模型,观察模拟失重对兔庆大霉素药代动力学参数的影响。７只家兔在头低位７ｄ前后,分别静脉滴注了３ｍｇ／ｋｇ的庆大霉素,用ＴＤｘＦＬｘ测定了给药后４ｈ内的血药浓度。结果 庆大霉素的分布变慢,这表现在α值由头低位前的（０．１８３８±０．１０７６）ｍｉｎ＾－１降至头低位后的（