Effects of pre-motion electromyographic silent period on dynamic force exertion during a rapid ballistic movement in man

Summary The effects of pre-motion silent period (PSP) on dynamic force exertion were studied in ten healthy subjects performing ballistic elbow extensions. The experiments were designed to evaluate the significance of mean differences between the averaged dynamic force curves of two groups: PSP-presence groups and PSP-absence groups. The presence of PSP was judged quantitatively and automatically by means of a newly developed method using statistical analysis. The results indicated that there were two effects of PSP on dynamic force exertion: one was a reducing effect, observed prior to the movement; the other was a reinforcing effect, observed in the first part of the ballistic movement. The duration of the reinforcement was significantly correlated with the duration of the reducing effect of PSP. The findings suggested that the reinforcement of dynamic force may be produced by the pre-stretch of agonistic muscles caused by prior force reduction due to PSP occurrence. The fact that PSP plays an important role in dynamic force exertion suggests that PSP may be incorporated in the central motor control system designed to interrupt the background activity, to stretch the agonist and to reinforce the dynamic force.     

适用于医学动态监测数据的稳健参数估计方法

目的 :介绍并分析适用于医学动态监测数据的稳健参数估计方法。方法 :结合分布假设和稳健统计给出了参数估计方法。首次提出了一种迭代求取形状参数稳健估计的算法。结果 :该方法对医学动态监测中某种生理量异常所占百分比值统计量的参数估计优于临床普遍采用的方法。结论 :通过对分布拟合、估计优效性和可实现性、估计稳健性等的理论分析和模拟实验表明该方法是一种高效、可靠的稳健参数估计方法     

Learned control of heart rate during exercise in patients with borderline hypertension

Summary Twelve patients with borderline hypertension [⩽21.33/12.6, ⩾18.6/12.0 kPa (⩽160/ 95; ⩾ 140/90 mm Hg)] participated in an experiment aimed at testing whether they could learn to attenuate heart rate while exercising on a cycle ergometer. Six experimental (E) subjects received beat-to-beat heart-rate feedback and were asked to slow heart rate while exercising; six control (C) subjects received no feedback. Averaged over 5 days (25 training trials) the exercise heart-rate of the E group was 97.8 bt min⁻¹, whereas the C group averaged 107 bt min⁻¹ (P=0.03). Systolic blood pressure was unaffected by feedback training. Generally, changes in rate-pressure product reflected changes in heart-rate. Oxygen consumption was lower in the E than in the C group late in training. We conclude that neurally mediated changes associated with exercise in patients with borderline hypertension can be brought under behavioral control through feedback training.     

微创DHS内固定与传统DHS内固定治疗老年股骨粗隆间骨折比较研究

目的:对微创动力髋螺钉(dynamic hip screw,DHS)内固定和传统DHS内固定治疗老年股骨粗隆间骨折的效果进行比较.方法:将91例老年股骨粗隆间骨折患者随机分为两组,传统组46例采用传统方式置入内固定物治疗,微创组45例采用微创方式置入内固定物.对两组手术创伤大小、术后并发症、骨折愈合及功能恢复情况进行比较.主要通过考察手术切口长度、出血量、输血量、血红蛋白下降幅度、术后术区肢体肿胀情况、血沉变化等来反映手术创伤大小.结果:两组手术创伤差异有统计学意义,传统组大于微创组(P＜0.05).微创组有2例复位不良,传统组有3例复位不良,两组均无深部血肿发生.传统组围手术期死亡2例,其余患者均顺利出院,获12～30个月随访,平均17.1个月.两组各有1例在随访期间死于其它内科疾病,其余骨折均获愈合.术后平均骨折愈合时间微创组3.6个月,传统组3.8个月.术后1年髋关节功能优良率微创组84.1%,传统组79.1%,两组差异无统计学意义(P＞0.05).结论:微创DHS内固定治疗老年股骨隆间骨折,手术创伤小,有利于围手术期恢复和髋关节功能康复.     

Evaluating plasma holds in the presence of multiple infections

To protect plasma supplies, donors are screened for infectiousdiseases. As an added measure of protection, donations are identifiedand stored for a period of time to allow future discard in theevent that an identified donor subsequently tests positive forsome screened disease. Previous models for evaluating such plasmaholds have only addressed the case of a single infectious disease.This paper extends the analysis to the case of multiple infections.Given knowledge of the marginal incidence rates for those infectionschecked, upper and lower bounds for important quantities suchas the probability of interdicting an infectious but undetecteddonation, the expected number of infections interdicted perdonation, and the net economic benefits of the holding policyare developed. Several examples are developed, illustratinghow the models can be used to evaluate the consequences of aplasma hold.     

基于实时三维超声图像的二尖瓣环重建及运动分析

二尖瓣环的非平面特性对二尖瓣返流的超声诊断和二尖瓣环成形术的合理设计具有重要意义.基于心脏的实时三维超声图像,我们研究了一种对二尖瓣环三维重建及运动分析的方法.首先通过人机交互方式提取出二尖瓣环的特征点,并根据位置关系对特征点排序,然后利用非均匀有理B样条曲线建立二尖瓣环三维形态模型,并编程实现二尖瓣环的动态显示和运动分析.通过对20组病例分析,初步证明此方法所建模型较准确反映患者的二尖瓣环的运动,能满足二尖瓣环三维可视化和分析研究的需要.     

Physical work capacity in dynamic exercise with differing muscle masses in healthy young and older men

Ten young (aged 23–30 years) and nine older (aged 54–59 years) healthy men with similar estimated limb muscle volumes performed, in random order, three different types of ergometer exercise tests (one-arm cranking, two-arm cranking, and two-leg cycling) up to the maximal level. Values for work load (WL), peak oxygen consumption , peak heart rate (HR), peak ventilation , respiratory gas exchange ratio (R), recovery blood lactate concentration [La^–], and rating of perceived exertion (RPE) were compared between the age-groups in the given exercise modes. No significant age-related differences in WL, peak , peak HR, R, [La^–], or RPE were found in one-arm or two-arm cranking. During one-arm cranking the mean peak was 1.65 (SD 0.26)1 · min^–1 among the young men and 1.63 (SD 0.10)1 · min^–1 among the older men. Corresponding mean peak during two-arm cranking was 2.19 (SD 0.32)1 · min-1 and 2.09 (SD 0.18)1 · min^–1, respectively. During one-arm cranking peak was higher (P < 0.05) among the older men compared to the young men. During two-leg cycling the young men showed higher values in WL (P < 0.001), peak (P < 0.001), and peak HR (P < 0.001). The mean peak was 3.54 (SD 0.24)1 · min^–1 among the young men and 3.02 (SD 0.20)1 · min^–1 among the older men. Corresponding mean peak HR was 182 (SD 5) beats · min^–1 and 170 (SD 8) beats · min^–1, respectively. During two-leg cycling, peak , R, [La^–], and RPE did not differ between the two age-groups. In summary, the older men with similar sizes of estimated arm and leg muscle volumes as the young men had a reduced physical work capacity in two-leg cycling. In one-arm or two-arm cranking, no significant difference in work capacity was found between the age-groups. These results indicate, that in healthy men, age, at least up to the 6th decade of life, is not necessarily associated with a decline in physical work capacity in exercises using relatively small muscle groups, in which the limiting factors are more peripheral than central.     

动态脑电图对缺血缺氧性昏迷病人的预后评估

目的：观察动态脑电图和临床检测指标对缺血缺氧性昏迷病人预后的评估价值。方法：在45例缺血缺氧性昏迷病人急性期进行动态脑电图检测和Glasgow评分、瞳孔对光反应、脑干反应检查，随访3个月时病人的预后，将动态脑电图检测和各项临床检查结果与病人的预后结果进行相关分析。结果：动态脑电图对昏迷病人预后的评估在敏感性(83．3％)、特异性(100％)和对预后评估的准确率(91．7％)方面均比临床检测结果高，临床指标Glasgow评分、瞳孔对光反射、脑干反射的敏感性、特异性及准确率分别为73．1％、84．2％及77．9％；76.9％、73．7％及75．6％；76．0％、68.4％及68．9％。结论：动态脑电图检测对急性缺血缺氧性昏迷病人预后的评估有确定的价值。     

利用表面肌电信号评价肌肉疲劳的方法

表面肌电信号分析是评价局部肌肉疲劳有效的工具。过去由于受信号处理技术的限制,对肌肉疲劳的评价仅局限于等长、恒力收缩。由于适合于非平稳信号分析的频谱估计技术的发展,使得动态收缩条件下的肌肉疲劳评价得以实现,在工效学、康复医学和运动医学等方面开启了新的应用领域。本文论述了利用表面肌电信号评价肌肉疲劳,特别是在肌肉动态收缩期间评价肌肉疲劳的方法,为进一步探讨肌肉疲劳的发生机制提供理论依据。     

Differential thermosensitivity and electric prepolarization of the ampullae of Lorenzini

Summary In single-fibre preparations the afferent discharges from prepolarized ampullae of Lorenzini responding to graded temperature steps were investigated in the dogfish (Scyliorhinus canicula).The transformation characteristics of the ampullary receptors, especially their differential thermosensitivity interfering with electrosensitivity, were analyzed. Prepolarization significantly influenced the dynamic component of differential thermosensitivity, while the static component remained practically unchanged. Hyperpolarization reduced positive and negative dynamic thermal responses: depolarization amplified them.Biological consequences of this bimodal interference for receptor transformation of superimposed thermal and electric stimuli and for decoding afferent ampullary impulse patterns are discussed.This investigation was supported by the Deutsche Forschungsgemeinschaft