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71.
Six men and four women performed, in separate trials, maximal dynamic knee extensions with loads of 15%, 30%, 45% and 60%
of maximal isometric knee extension peak torque (MVC). The dynamic extensions were done after postactivation potentiation
(PAP) had been induced with a 10-s MVC, and in a control trial without PAP. PAP, measured as the increase in evoked twitch
torque, was 53 (4)% (SE) and 43 (3)% at the time of the first and second extensions with each load. PAP failed to increase
the attained peak velocity with any load; on the contrary, there was a trend for peak velocity to decrease in the first extension,
which occurred ≅15 s after the 10-s MVC. The results suggest that fatigue produced by the 10-s MVC suppressed any benefit
that could be derived from the induced PAP. A surface electromyogram (EMG) recorded from one muscle of quadriceps femoris
gave no indication of activation failure in the first knee extension; however, activation impairment specific to the rate
of force development cannot be ruled out. It is concluded that the strategy employed, namely of having knee extensions performed
soon after the 10-s MVC to maximize PAP at the time of performance, was unsuccessful because there had been insufficient time
for recovery from fatigue. It is possible that a longer recovery time, even at the cost of a diminished PAP, may have proved
beneficial.
Accepted: 27 July 2000 相似文献
72.
A linear mathematical model of the electromyogram (e.m.g.) has been developed for the biceps muscle. The number of motor units (and therefore muscle fibres) contributing to the resultant e.m.g. at any stage of movement has been found from the force analysis of elbow flexion. The depths of various motor units and the phase difference between the recruitment of any two motor units have been formulated using a spiral spread of recruitment sequence. The attenuation of individual motor-unit action potentials due to varying depths has been taken into consideration, and due regard has been taken of the length-tension diagram of a muscle while performing the force analysis. Attention has been focused on the flexion of the elbow joint, in which a method of finding the individual contribution of the biceps and brachialis muscles has been developed and applied. The results predicted by the model have been verified by experiments. The model can also be extended to the e.m.g. of other fast skeletal muscles. The conditions and limitations for such generalisations have been stated and discussed. 相似文献
73.
Adult rats emit 22 kHz ultrasonic vocalizations (USVs) in response to aversive stimuli, and these sounds are suggested to have communicative information among conspecifics. It is conceivable that social environment during development of rats has relevance to the emission of 22 kHz USVs. To examine the effects of social environment after weaning on production of stress-induced USVs, we compared the amount of emission of USVs among three groups of rats reared under different conditions after weaning. One group of rats was housed individually, and the other two groups were housed in pairs, in which social hierarchy of the pair was determined by social dominance-subordination relationships. The USVs were induced by acute mild somatic stimuli on the back and neck. Individually reared rats emitted much fewer USVs than pair-reared rats. In addition, socially subordinate rats emitted more USVs compared with socially dominant ones. These results suggest that not only social interaction but also the status in social hierarchy may play an important role in the process of the development of USVs induced by somatic stimuli. 相似文献
74.
R Arriagada H Mouriesse D Sarrazin R M Clark G Deboer 《International journal of radiation oncology, biology, physics》1985,11(10):1751-1757
This retrospective study involved 463 breast cancer patients treated by radiotherapy alone at the Princess Margaret Hospital and at the Institut Gustave-Roussy. These patients either had operable tumors, but were unfit for general anesthesia, or had inoperable tumors due to local contraindications to surgery. Results were analyzed according to tumor response, local recurrence rate, tumor size, tumor fixation, nodal fixation and tumor dose. Conventional statistical analysis of local control showed two significant factors: tumor dose and tumor size. Multivariate analysis permitted to define an "individual risk" (IR) of local recurrence according to three independent factors: tumor size, tumor fixation, and nodal fixation. It was shown that the IR was a good prognostic factor for local control. Increase in tumor dose gave a similar effect in the local recurrence relative risk for all the IR groups. According to the slope of the dose-effect curve, it was deduced that a dose increase of 15 Gy can decrease the relative risk of local recurrence 2-fold. In fact, it was shown that tumor dose was the most significant independent factor on local control, able to produce up to a 10-fold increase compared to 2-fold decrease for tumor size. If the IR of local recurrence is known, a theoretical predictive value on local control, taking into account the tumor dose, can be determined according to the present data. 相似文献
75.
Dr. O. N. Bershitskaya V. Ya. Izakov L. T. Lysenko J. L. Protsenko A. V. Trubetskoy 《Basic research in cardiology》1985,80(2):156-164
Summary The relationship heart rate-left ventricular pressure was investigated in the isolated canine heart perfused with constant pressure at different preloads. Rhythmical stimulation was performed with constant stimulus interval duration and with stimulus intervals randomly changed near the average value (150–200 stimuli in series).Correlation and dispersion function analysis show that rhythm dispersion had a negative inotropic effect which was independent of the preload of the ventricle in the range of 120–180 beat/min, but this dependence occurred with low rates of stimulation.This method is proposed for the assessment of contractility under conditions of heart rate variations (physiological and pathological arrhythmias). 相似文献
76.
Tang-Liu Diane D. -S. Liu Sandra 《Journal of pharmacokinetics and pharmacodynamics》1987,15(4):387-397
The differences in flurbiprofen disposition in the aqueous humor and the plasma were examined after systemic doses. Steady state plasma concentrations of flurbiprofen (20–60 g/mL) were achieved via intravenous infusion to albino rabbits. Flurbiprofen demonstrated linear systemic kinetics throughout the dosing range, with constant body clearance and unbound fraction in plasma. At steady state, aqueous humor drug concentrations depended on the corresponding plasma drug concentration. Two clearance terms—CLso, the systemic clearance to ocular tissues, and CLos, the ocular clearance to systemic circulation—were used. After systemic doses, the drug concentration in the aqueous humor was related to that in the plasma as well as to the ratio of these two clearances. Flurbiprofen was extensively bound to plasma proteins and showed limited ocular distribution; its CLso to CLso tratio was very small. Thus, the concentration of flurbiprofen in the aqueous humor after systemic doses was lower than that obtained after ophthalmic doses. A plasmapheresis technique was utilized to lower the plasma protein concentrations to 60% of normal levels. As a consequence, flurbiprofen demonstrated reduced aqueous humor protein concentrations, increased unbound fractions in the plasma and the aqueous humor, elevated aqueous humor drug concentrations, and elevated total body clearance. The unbound body clearance stayed unchanged. Our study indicated that a drug should present a significant CLso/CLos ratio in order to achieve therapeutic concentrations in the eye via systemic doses. The drug-protein binding kinetics can be different between the plasma and the aqueous humor circulations. Because the ocular compariment is very small compared to the overall systemic distribution of flurbiprofen, it has little effect on the steady state systemic concentrations. 相似文献
77.
[摘要] 目的 初步探索血清白蛋白水平与新型冠状病毒肺炎长期阳性患者病毒转阴之间的因果关系。方法?以病程超过30 d的轻型新型冠状病毒肺炎住院患者为研究对象,采集人口学信息、治疗策略、合并疾病、实验室检查指标信息,以发病后45 d内病毒累积转阴率为因变量,以发病后(30±3)d时的血清白蛋白水平为主要分析变量,以人口学信息、治疗策略、合并疾病、实验室检查结果等其他信息为协变量,采用限制立方样条回归-Cox比例风险回归模型探讨血清白蛋白水平对累积转阴率的影响。结果?共有189例患者纳入分析,其中101例在45 d内实现了病毒转阴。进一步分析发现,30 d时的血清白蛋白水平与45 d病毒累积转阴率之间存在相关性(P = 0.027)。当血清白蛋白<39 g/L时,低血清白蛋白水平是病毒转阴的危险因素,且血清白蛋白水平越低,风险比(hazard ritio, HR)越高,血清白蛋白越接近39 g/L,HR则越接近1;当血清白蛋白≥39 g/L时,血清白蛋白水平不再是病毒转阴的危险因素。结论?血清白蛋白水平与患者的病毒转阴密切相关,当血清白蛋白<39 g/L时,血清白蛋白水平越低,越不利于病毒转阴。因此,治疗过程中关注血清白蛋白变化,及时给予干预,可能有利于病毒转阴。 相似文献
78.
文化建设与党建工作之间存在着一定的关联,随着经济的不断发展,我国卫生管理体制改革也不断深入,在此过程中,对于高校附属医院文化建设和党建工作提出更高水平的要求。从医院层面来看,通过加强文化建设以及发展党建工作,能够有效提高医院的凝聚力,促进医院树立良好的形象、培养优秀的医护人员等。文化建设和党建工作息息相关,在医院管理与发展的过程中,两者之间相辅相成。文章在研究的过程中,采用访谈法、问卷调查法等方法,通过访谈法、问卷调查法对医院各个方面人员进行调查,根据调查结果总结高校附属医院文化建设和党建工作的关系。 相似文献
79.
面对医疗卫生事业改革的新形势、新任务,医院办公室应该更新观念,树立改革创新意识、大局意识、法制意识、市场竞争意识和以病人为中心的意识;积极参与医院改革、成本核算、组建医疗集团、建立医院信息系统、开拓医疗服务市场、参与市场竞争等医院重点工作;建立和协调好对内对外的关系,在医院改革与发展中发挥积极作用。 相似文献
80.