Is coordination variability using vector coding different in overground and treadmill walking and running?

BackgroundCoordination variability has been linked to overuse running injuries and has been studied both on a treadmill and over-ground. It is not clear, however, if the coordination variability data from over-ground locomotion can be compared with treadmill locomotion data.Research questionTherefore, the purpose of this study was to compare coordination variability of selected lower extremity couplings at different locomotor speeds during over-ground and treadmill walking and running.MethodsNineteen (10 female, 9 male) healthy, recreational collegiate runners participated in this study. Each participant performed in two different conditions: over-ground and on a treadmill at three walking speeds (1.2, 1.6, and 2.0 m•s⁻¹) and three running speeds (2.8, 3.2, and 3.6 m•s⁻¹). A modified vector coding technique was used to calculate coordination variability for five selected coupled segment and joint angles. Each of the segmental couples was analyzed separately using a two-way repeated measures ANOVA (Condition Χ Speed) implemented with one-dimensional statistical parametric mapping.ResultsWhile no interaction effects were observed for condition X speed, we saw increased coordination variability in the sagittal couples during overground compared with treadmill locomotion, which predominantly occurred during the stance phase. There were mixed results for changes in coordination variability as a function of gait speed. However, for the sagital plane couplings, coordination variability decreased with speed, particularly during the stance phase.SignificanceThese results suggest that the controlled belt speed of the treadmill affects the intrinsic dynamics of human movement and this should be considered when making comparisons between treadmill and over-ground studies and in future study designs.     

不同联律间期室性期前收缩刺激对窦性心率震荡的影响

目的观察不同联律间期室性期前收缩刺激对窦性心率震荡的影响。方法对20例阵发性室上性心动过速（PSVT）患者,分别通过动态心电图行自发性心率震荡检测和通过心室程序刺激行诱发性心率震荡检测,比较不同联律间期室性期前收缩刺激所诱发的窦性心率震荡参数[震荡初始（TO）和震荡斜率（TS）]的差异。结果自发性窦性心率震荡[（-2.29±1.47）%、（10.14±5.71）ms/R-R]与诱发性窦性心率震荡[（-1.71±1.36）%、（7.12±4.68）ms/R-R]比较,差异均无统计学意义（均P＞0.05）,右心室心尖部、右心室流出道室性期前收缩的联律间期与诱发性窦性心率震荡参数TO和TS均有较好的相关性（r＝-0.825、-0.793、-0.712、-0.689,P＜0.01）。结论诱发性窦性心率震荡与自发性窦性心率震荡具有一致性,心室不同刺激部位对诱发性窦性心率震荡结果无明显影响,室性期前收缩的联律间期与诱发性窦性心率震荡参数有相关性,动态心电图记录中心室不同部位和不同联律间期的室性期前收缩所计算的心率震荡参数值均有较高的可信度。     

Protein kinase Cε mediates salutary effects on electrical coupling induced by ischemic preconditioning

BACKGROUND: Ischemic preconditioning delays the onset of electrical uncoupling and prevents loss of the primary ventricular gap junction protein connexin 43 (Cx43) from gap junctions during subsequent ischemia. OBJECTIVE: To test the hypothesis that these effects are mediated by protein kinase C epsilon (PKCepsilon), we studied isolated Langendorff-perfused hearts from mice with homozygous germline deletion of PKCepsilon (PKCepsilon-KO). METHODS: Cx43 phosphorylation and distribution were measured by quantitative immunoblotting and confocal microscopy. Changes in electrical coupling were monitored using the 4-electrode technique to measure whole-tissue resistivity. RESULTS: The amount of Cx43 located in gap junctions, measured by confocal microscopy under basal conditions, was significantly greater in PKCepsilon-KO hearts compared with wild-type, but total Cx43 content measured by immunoblotting was not different. These unanticipated results indicate that PKCepsilon regulates subcellular distribution of Cx43 under normal conditions. Preconditioning prevented loss of Cx43 from gap junctions during ischemia in wild-type but not PKCepsilon-KO hearts. Specific activation of PKCepsilon, but not PKCdelta, also prevented ischemia-induced loss of Cx43 from gap junctions. Preconditioning delayed the onset of uncoupling in wild-type but hastened uncoupling in PKCepsilon-KO hearts. Cx43 phosphorylation at the PKC site Ser368 increased 5-fold after ischemia in wild-type hearts, and surprisingly, by nearly 10-fold in PKCepsilon-KO hearts. Preconditioning prevented phosphorylation of Cx43 in gap junction plaques at Ser368 in wild-type but not PKCepsilon-KO hearts. CONCLUSION: Taken together, these results indicate that PKCepsilon plays a critical role in preconditioning to preserve Cx43 signal in gap junctions and delay electrical uncoupling during ischemia.     

基于电磁感应的消化道内微系统无线能量传输问题研究

针对消化道内微小系统,提出一种基于电磁耦合的无线能量传输方案.通过计算线圈间的互感,分析了相对位置对耦合系数的影响.建立了能量传输模型,推导出弱耦合情况下接收功率最大化的条件,指出提高传输效率的两种方法.实验传输功率超过200 mW(接收线圈位于发射线圈中心),验证了这种方案的可行性.     

Temperature dependence of electro-mechanical coupling in crayfish muscle fibers

Summary In single fibers of crayfish muscle the membrane was clamped to definite potentials for periods of 10 ms to 10 s. Contraction of the fiber was measured isometrically. The influence of temperature on the relations between contraction and amplitude as well as duration of depolarization was determined.Upon cooling the preparation from 20 to 10°C maximum force of contraction decreased with a Q ₁₀ of 3, while the rate of rise of contraction was reduced even more. Relaxation was more slowed by cooling than contraction. The Q ₁₀ of the delay of relaxation relative to repolarization and of the rate of relaxation were in the range of 3–10. The results suggest that cooling decreases the amplitude of the active state and slows its rise and decay. Only one of the measured parameters had a low Q ₁₀ of 1.2, namely the period of continued increase of rate of rise of contraction after repolarization. A state of excitation of an internal membrane system continued after repolarization of the surface membrane could explain this finding.This work was supported by the Deutsche Forschungsgemeinschaft.     

Coupling mode of receptors and G proteins

Signaling via G-protein-coupled receptors (GPCRs) is crucial to many physiological and pathophysiological processes in multicellular organisms, and GPCRs themselves are targets for important drugs. Classical cell supplementation experiments suggest a collision coupling model, in which receptors and G proteins diffuse randomly within the cell membrane and interact only if receptors are activated. This model is also backed by kinetic and live cell imaging data. According to the challenging theory, receptors and G proteins are precoupled—meaning they are forming stable complexes in the absence of agonist, which prevail during signaling. This model has been favored on the basis of copurification and coimmunoprecipitation of inactive receptors with G proteins and more recently by some approaches measuring energy transfer between labeled receptors and G proteins. This article reviews key findings regarding the receptor/G protein coupling mode, including most recent findings obtained by optical techniques.     

耦合剂充盈法腔内超声对直肠癌术前T分期的诊断价值

目的 评价耦合剂充盈法腔内超声在直肠癌术前T分期诊断中的价值.方法 对115例直肠癌患者行耦合剂充盈法腔内超声检查,进行术前T分期,并与手术及术后病理分期对照.结果 115例直肠癌术前T分期诊断总符合率89.57%,T1、T2、T3、T4期诊断灵敏度和特异度分别为93.10%、61.11%、96.61%、88.89%和97.67%、96.91%、89.29%、99.06%;过度判断6.96%(8/115),判断不足3.48%(4/115).结论 耦合剂充盈法腔内超声在直肠癌术前T分期诊断中有重要价值.     

Coupling of resorption and formation on bone remodeling sequence in orthodontic tooth movement: A histochemical study

Rat's molars were submitted to orthodontic tooth movement. Bone formation areas were detected using lead-labeling technique. Osteoclasts and osteoblasts were detected by enzyme histochemistry using Tartrate resistant Acid phosphatase (TRACPase) and Alkaline phosphatase (ALPase) to determine simultaneously and mark the 2 types of cells on a same section. The sites selected for study were pressure/distal, tension/mesial and transitional areas of second molars. The results showed that: orthodontic force activated bone remodeling sequence throughout the alveolar bone; slight new bone formation was observed on the cement line on the pressure side. ALPase-positive cells were detected on the pressure side neighboring osteoclasts. On the tension side, bone formation was enhanced in the protrusions whereas both resorption and formation were observed in the depressions. In the transitional area, cellular sequence from osteoclastic bone resorption to bone formation was revealed over the cement line. These findings demonstrated that: coupling phenomena occur on the pressure side but with inhibited osteoblast activity. Bone formation on the tension side involves both promotion of bone formation by the traction force; bone remodeling sequence is established on the tension side by the interaction between osteoclastic bone resorption and bone formation that takes place in the depressions; Coupling phenomena occur in the transitional area as well. Our findings on the pressure side led to the consideration that osteoblastic cells in periodontal ligament would be involved in the regulation of osteoclastic bone resorption. Thus, there appears to be an interaction between osteoclastic and osteoblastic cells and an activated bone remodeling sequence involving the coupling phenomena as a mechanical adaptation to orthodontic force.