Characterization of the mouse ClC-K1/Barttin chloride channel

Several Cl⁻ channels have been described in the native renal tubule, but their correspondence with ClC-K1 and ClC-K2 channels (orthologs of human ClC-Ka and ClC-Kb), which play a major role in transcellular Cl⁻ absorption in the kidney, has yet to be established. This is partly because investigation of heterologous expression has involved rat or human ClC-K models, whereas characterization of the native renal tubule has been done in mice. Here, we investigate the electrophysiological properties of mouse ClC-K1 channels heterologously expressed in Xenopus laevis oocytes and in HEK293 cells with or without their accessory Barttin subunit. Current amplitudes and plasma membrane insertion of mouse ClC-K1 were enhanced by Barttin. External basic pH or elevated calcium stimulated currents followed the anion permeability sequence Cl⁻ > Br⁻ > NO₃⁻ > I⁻. Single-channel recordings revealed a unit conductance of ~ 40 pS. Channel activity in cell-attached patches increased with membrane depolarization (voltage for half-maximal activation: ~ − 65 mV). Insertion of the V166E mutation, which introduces a glutamate in mouse ClC-K1, which is crucial for channel gating, reduced the unit conductance to ~ 20 pS. This mutation shifted the depolarizing voltage for half-maximal channel activation to ~ + 25 mV. The unit conductance and voltage dependence of wild-type and V166E ClC-K1 were not affected by Barttin. Owing to their strikingly similar properties, we propose that the ClC-K1/Barttin complex is the molecular substrate of a chloride channel previously detected in the mouse thick ascending limb (Paulais et al., J Membr. Biol, 1990, 113:253–260).     

在320排螺旋CT双下肢动脉成像中的护理配合效应

目的：探讨320排螺旋CT血管成像（CTA）在行双下肢动脉血管成像过程中,护理配合对的图像质量的影响。方法：将138例患者分为护理组（82例）及对照组（56例）,分别进行320排螺旋CT双下肢血管造影检查,经高压团注造影剂欧乃派克,进行三维重组,获取容积再观（VR）、曲面重组（CPR）和最大密度投影（MIP）图像。对照组的患者只进行口头的训练,没有其他的护理干预措施;实验组进行一系列的护理干预以提高患者的配合,减低在成像过程中的非生理性运动。用工作站进行图像后处理,显示双下肢动脉图像,对其图像质量和影响因素进行分析,并在检查过程中的护理干预加以总结。结果：对照组有2例患者穿刺部位不合理而影响图像质量,对双下肢的病变显示具有一定的影响,3例患者注射压力过高引起外渗,流速在2.5-3.5 ml/s,影响了图像的清晰度,其余均获得满意效果。结论：良好的护理配合有利于320排CT双下肢成像的顺利进行,精心的护理操作是取得检查成功的动脉成像保证。     

Strength of forelimb lateralization predicts motor errors in an insect

Lateralized behaviours are widespread in both vertebrates and invertebrates, suggesting that lateralization is advantageous. Yet evidence demonstrating proximate or ultimate advantages remains scarce, particularly in invertebrates or in species with individual-level lateralization. Desert locusts (Schistocerca gregaria) are biased in the forelimb they use to perform targeted reaching across a gap. The forelimb and strength of this bias differed among individuals, indicative of individual-level lateralization. Here we show that strongly biased locusts perform better during gap-crossing, making fewer errors with their preferred forelimb. The number of targeting errors locusts make negatively correlates with the strength of forelimb lateralization. This provides evidence that stronger lateralization confers an advantage in terms of improved motor control in an invertebrate with individual-level lateralization.     

Cortical motor representation of the rectus femoris does not differ between the left and right hemisphere

Transcranial magnetic stimulation (TMS) involves non-invasive magnetic stimulation of the brain, and can be used to explore the corticomotor excitability and motor representations of skeletal muscles. However there is a lack of motor mapping studies in the lower limb and few conducted in healthy cohorts. The cortical motor representations of muscles can vary between individuals in terms of center position and area despite having a general localized region within the motor cortex. It is important to characterize the normal range for these variables in healthy cohorts to be able to evaluate changes in clinical populations. TMS was used in this cross-sectional study to assess the active motor threshold (AMT) and cortical representation area for rectus femoris in 15 healthy individuals (11 M/4F 27.3 ± 5.9 years). No differences were found between hemispheres (Left vs. Right P = 0.130) for AMT. In terms of y-axis center position no differences were found between hemispheres (Left vs. Right P = 0.539), or for the x-axis center position (Left vs. Right P = 0.076). Similarly, no differences in calculated area of the motor representation were found (Left vs. Right P = 0.699) indicating symmetry between hemispheres.     

Comparison of Biomechanical Characteristics during the Second Landing Phase in Female Latin Dancers: Evaluation of the Bounce and Side Chasse Step

Research on dance lower extremity joint motion has been limited. Thus, the purpose of this study was to investigate the lower limb biomechanics differences between the side chasse step (SCS) and the bounce step (BS) of the second landing phase in Jive. Thirteen female recreational Latin dancers (Age: 22 ± 2.5 years; Height: 1.65 ± 0.05 m; Weight: 50 ± 4.5 kg; Dance experience: 4 ± 2 years) were involved in the experiment. The same music was used throughout the data collection period. We intended to determine whether these two steps generate different kinematic and kinetic data. The ankle, hip, and knee joint angle, moment, velocity, and ground reaction force were calculated for each step. Results demonstrated that the lower limb biomechanics of the two different steps showed significant differences. As a result, strengthening the lower limb muscles (gastrocnemius, Tibialis muscle, and quadriceps) is significantly important to balance the joint strength and prevent foot injury. According to the training time reasonably increasing the heel height should be recognized as important. The current study could provide new insights into reducing lower extremity injuries and improving dance performance.     

The relative contributions of sagittal,frontal, and transverse joint works to self-paced incline and decline slope walking

Positive and negative work are generated at the lower limb joints in order to locomote over various terrains. Joint work quantifies the changes in energy that are necessary to adapt gait to environmental demands. The aim of this study was to quantify 3D joint work at the hip, knee, and ankle during slope walking. Work was calculated for ten males (23.9 ± 1.1 years) walking at a self-selected speed on inclines and declines (−20, −12, −6, 0, 6, 12, 20 degrees). Sagittal positive work significantly increased at the hip, knee, and ankle for incline walking (for example, hip positive work increased 153%, 280%, and 453% for 6, 12, and 20 degrees, respectively; knee and ankle positive work also increased) (p ≤ 0.05), in order to raise and propel the body forward. Sagittal negative work increased significantly at the hip, knee and ankle for decline walking (for example, knee negative work increased 193%, 355%, and 496% for −6, −12, and −20 degrees, respectively; hip and ankle negative work also increased) (p ≤ 0.05), in order to control body descent. These substantial changes in work will be especially challenging for people with compromised strength due to age and disease. Furthermore, changes in work were not limited to the sagittal plane: 46% of the total hip joint work occurred in the frontal and transverse planes for six degree decline walking. Thus, decline walking placed greater demands on the hip ab/adductors and rotators, and this may be related to the greater risk of falls observed for descent versus ascent.     

Polydactyly in the Strong's luxoid mouse is suppressed by limb deformity alleles

The study of limb development has provided insight into pattern formation during vertebrate embryogenesis. Genetic approaches offer powerful ways to identify the critical molecules and their pathways of action required to execute a complex morphogenetic program. We have applied genetic analysis to the process of limb development by studying two mouse mutants, limb deformity (Id) and Strong's luxoid (Ist). These mutations confer contrasting phenotypic alterations to the anteroposterior limb pattern. The six mutant Id alleles are fully recessive and result in oligosyndactyly of all four limbs. By contrast, the two mutant Ist alleles result in a mirror-image polydactylous limb phenotype inherited in a semidominant fashion. Morphological and molecular analysis of embryonic limbs has shown that the Id and Ist alleles affect the extent and distribution of two key signaling centers differentially: the apical ectodermal ridge and the zone of polarizing activity. Molecular characterization of the Id gene has defined a new family of evolutionarily conserved proteins termed the formins. The underlying molecular defect in the Ist mutation has not been identified; however, both loci are tightly linked on mouse chromosome 2, suggesting the possibility that they may be allelic. In this study, we have used genetic analysis to examine the epistatic and allelic relationships of Id and Ist. We observed that in + Id/Ist + double heterozygotes, a single mutant Id allele is able to suppress the semi-dominant polydactylous Ist limb phenotype. By segregating the Ist and Id loci in a backcross, we observed that these loci recombine and are separated by a genetic distance of approximately 6 cM. Therefore, while our observations demonstrate a genetic interaction between Id and Ist, it is probable that Id and Ist are not allelic. Instead, Ist and Id may be operating either in a linear or in a parallel (bypass) genetic pathway to affect the limb signaling centers. © 1996 Wiley-Liss, Inc.     

Patented Biologically-inspired Technological Innovations： A Twenty Year View

1 Introduction Biomimetics or bionics is having an increasing role in innovation[1]. It offers the promise of novel routes to technological innovation; a recent paper highlighted the potential of studies of biological systems to initiate patents in the engineering sciences and technology[2]. Media coverage, particularly in business periodicals is increasing, for example, The Economist recently re- ported on the growth of biomimetics and its impact on technology[3]. There are two principal rou…