Eccentric and concentric torque-velocity characteristics of the quadriceps femoris in man

Summary The primary purpose of this investigation was to study the eccentric and concentric torque-velocity characteristics of the quadriceps femoris in man using a recently developed combined isometric, concentric and eccentric controlled velocity dynamometer (the SPARK System). A secondary purpose was to compare the method error associated with maximal voluntary concentric and eccentric torque output over a range of testing velocities. 21 males (21–32 years) performed on two separate days maximal voluntary isometric, concentric and eccentric contractions of the quadriceps femoris at 4 isokinetic lever arm velocities of 0° · s^–1 (isometric), 30° · s^–1 120° · s^–1 and 270° · s^–1. Eccentric peak torque and angle-specific torques (measured every 10° from 30° to 70°) did not significantly change from 0° · s^–1 to 270° · s^–1 (p>0.05) (with the exception of angle-specific 40° torque, which significantly increased;p<0.05). The mean method error was significantly higher for the eccentric tests (10.6%±1.6%) than for the concentric tests (8.1%±1.7%) (p<0.05). The mean method error decreased slightly with increasing concentric velocity (p>0.05), and increased slightly with increasing eccentric velocity (p>0.05). A tension restricting neural mechanism, if active during maximal eccentric contractions, could possibly account for the large difference seen between the present eccentric torque-velocity results and the classic results obtained from isolated animal muscle.     

Hypothermic Machine Preservation in Liver Transplantation Revisited: Concepts and Criteria in the New Millennium

To overcome the present shortage of liver donors by expansion of the existing donor pool and possibly lengthening of the storage time, hypothermic machine perfusion of the liver as a dynamic preservation method is revisited. The three most important aspects are defined to be the type of preservation solution, the characteristics of perfusion dynamics, and the oxygen supply. Reviewing hypothermic liver machine perfusion experiments, the University of Wisconsin machine preservation solution is the solution most used. It is also found that nothing conclusive can be said about the optimal perfusion characteristics, since either perfusion pressure or perfusion flow is reported. The best estimation is perfusion of the liver in a physiological manner, i.e. pulsatile arterial perfusion and continuous portal venous perfusion. The applied pressures could be chosen to be somewhat lower than physiological pressures to prevent possible endothelial cell damage. Oxygen supply is necessary to achieve optimal preservation of the liver. The minimal amount of partial oxygen pressure required is inversely related to the normalized flow. Incorporating these features in a system based on existing standard surgical and organ sharing procedures and which is able to work stand-alone for 24 h, weighing less than 23 kg, could successfully implement this technique into every day clinical practise.     

CD8+T-bet+ cells as a predominant biomarker for inclusion body myositis

Background

Myositis is a heterogeneous group of muscular auto-immune diseases with clinical and pathological criteria that allow the classification of patients into different sub-groups. Inclusion body myositis is the most frequent myositis above fifty years of age. Diagnosing inclusion body myositis requires expertise and is challenging. Little is known concerning the pathogenic mechanisms of this disease in which conventional suppressive-immune therapies are inefficacious.

苯丙胺类兴奋剂(ATS)娱乐性使用情况及其人群特征

目的 :了解娱乐性ATS使用者的人口学特征 ,使用方式及其他有关问题。方法 :采用病例发现法和易接近对象晤谈法 ,并结合滚雪球的方法 ,以问卷方式收集娱乐性ATS使用者的有关资料。结果 :娱乐性ATS使用者平均年龄 2 3 97± 4 95岁。未婚占 6 4 4 % ,同居占 1 5 3% ,离婚占 8 5%。高中及以上文化者占 84 7%。职业以服务员、个体商人和性工作者居多。摇头丸是最主要的滥用药物。约 90 %的人使用次数少于 50次。口服是最主要的服用途径。平均每次服用剂量约为 2 50mg ,多在周末服用 ( 72 9% )。获得ATS的主要来源是从朋友和熟人处购买 ( 72 9% )。使用ATS的主要目的包括 :提高情绪使自己快乐 ,使自己压抑时感到舒服些 ,帮助放松 ,帮助解除抑制 (情绪、行为、思维 )等。娱乐性ATS使用者合并使用酒精 ,海洛因 ,苯二氮 艹卓 类 ,大麻 ,致幻剂的比例分别为 81 3% ,2 2 0 % ,1 1 9% ,1 0 2 % ,1 7%。 96 %的ATS使用者的主要社交人群中有人使用ATS。 4 5 8%和 33 8%的使用者有临时性伴侣和性交易史。结论 :娱乐性ATS使用者为一特殊人群 ,应针对其特殊性制定相应的干预措施。     

Signal Characteristics of EMG at Different Levels of Muscle Tension

Electromyographic activity of m. rectus femoris at submaximal and maximal voluntary contractions was quantified by conventional integration technique and also be a more “qualitative” procedure of automated motor unit averaging and frequency spectrum analysis. By relating the EMG parameters to produced muscle tension it was observed that the integrated EMG increased in a slightly nonlinear fashion with the increase in muscle force. The other EMG variables also showed clear changes as a function of muscle tension. The averaged motor unit potential (AMUP) and its specific parameters (number of spikes, amplitude, rise time and amplitude-rise time ratio) showed such changes with muscle tension that they may be useful in estimation of the recruitment pattern of the different types of motor units.     

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     

颞叶癫痫的临床特点与脑电图分析

目的：分析颞叶癫痫患的临床特点及脑电图定位的意义。方法：回顾分析92例颞叶癫痫患的脑电图。结果：左颞有癫痫样波42例，右颞有癫痫样波29例，双颞有癫痫样波21例，临床表现与癫痫样波发放部位有关，癫痫波的传导主要有容积传导和神经传导方式。结论：结合患临床表现与脑电图癫痫样波起始部位分析有助于致痫灶的定位。     

Spatial Characteristics of Cisterna Magna in Rats and Novel Technique for Puncture with a Stereotactic Manipulator

The actual size and sites for puncture of the cisterna magna in adult Wistar rats were estimated on acrylic models. We proposed a new method for obtaining cerebrospinal fluid from narcotized rats. This method consists in controlled introduction of a needle into the cisterna magna through the skin and/or dura mater above this structure using a stereotactic micromanipulator. Experiments on rats with focal and global cerebral ischemia showed that this technique ensures single and repeated sampling of at least 50 microl liquor not containing blood admixtures.     

Dustborne and airborne fungal propagules represent a different spectrum of fungi with differing relations to home characteristics

BACKGROUND: Exposure to fungi is often assessed by culturing floor dust or air samples. Our objective was to evaluate the relationships between dustborne and airborne fungi and to identify factors that modify these relationships. METHODS: From November 1994 to September 1996 sequential duplicate 45-l air samples were collected in bedrooms of 496 homes in the Boston area, using a Burkard culture plate sampler. After air sampling, bedroom floors were sampled with a vacuum cleaner that was modified to collect dust in a cellulose extraction thimble. Dust was sieved, and the fine dust was dilution-plated onto DG-18 media. RESULTS: Concentrations of total culturable fungi per gram of bedroom-floor dust were correlated weakly, but significantly, with those of indoor air (r = 0.13, P < 0.05). Concentrations of some individual taxa in the dust and indoor air were also weakly associated. Adjusting for the concentrations of fungi in outdoor air, dustborne fungal concentrations were positively associated with those in indoor air for the taxa Cladosporium and Penicillium, but not for total fungi. The indoor air fungal levels were often predicted by different covariates to those predicting fungal levels in dust. The type of housing (house or apartment) and the presence of carpeting were often predictive factors for dust fungi. In contrast, outdoor fungal levels were often predictive of the indoor air fungal levels. CONCLUSIONS: Because our data do not indicate a strong overall relationship between culturable fungi in dust and indoor air, the results from these two methods (dust and air sampling) likely represent different types of potential fungal exposures to residents. It may be essential to collect both air and dust samples, as well as information on housing characteristics, as indicators for fungal exposure.     

Sex differences in prefrontal volume with aging and Alzheimer's disease

We used volumetric magnetic resonance imaging to examine sex differences in prefrontal tissue volumes of healthy aged and patients with Alzheimer’s disease (AD). Healthy subjects had greater total prefrontal volume than AD, and men had greater total prefrontal volume than women (ps ≤ 0.02). This was true for both gray and white matter volumes. There were no interactions between group and sex for total prefrontal volume. An exploratory analysis of each group suggested that sex differences in both gray and white matter in healthy aging are not sustained in AD.