Electrical resistance of cell membranes in Necturus kidney

Summary The two-dimensional cable analysis for flat epithelia was made suitable for the study of current and voltage distribution in cylindrical epithelia which are assumed to have low paracellular shunt resistance. Applying the solutions to the proximal tubule of the doubly perfused volume-expanded Necturus kidney, the sum of cell membrane conductances in parallel, (g+g), was determined and found to be 0.56 mmho/cm². From this figure, the theoretical upper limit for the sum of membrane conductances in series may be estimated at 0.14 mmho/cm², though a figure of 0.105 mmho/cm² appears more realistic for this limit (membrane resistance in series equal to or greater than 9500 ohm·cm²). The core resistanvity, , of the proximal cell column was 11100 ohm·cm. When the kidney was perfused with sodium benzene sulfonate, choline chloride or LiCl, the figures for (g+g) and were 0.48 mmho/cm² and 15360 ohm·cm, 0.67 mmho/cm² and 55600 ohm·cm and 0.40 mmho/cm² and 4630 ohm·cm respectively.     

Dall-Miles绳爪系统在股骨粗隆间截骨术中的应用

本文总结了15例经股骨大粗隆截骨的粗隆间截骨术,术中应用Dall-Mils绳爪系统固定股骨大粗隆并辅助固定粗隆间截骨的结果。男性:2例;女性:13例。平均随访:7.5个月。其中,按照设计者方法施行手术6例,股骨大粗隆截骨部平均骨愈合时间为1.2个月,粗隆间截骨部为2个月;并发症中,1例大粗隆上移(<2cm),2例过牵,导至骨关节病期进展。应用改良方法9例,平均骨愈合时间分别为1.1个月和2.2个月;无并发症发生。改良方法的应用增加了股骨大粗隆的稳定性,并可对粗隆间截骨部起到辅助固定的作用。     

A simple device for eliciting tail pinch induced behavior in the rat

The device described is an inexpensive reliable means for eliciting tail pinch behaviors. As an improvement over previous methods it allows a wide range of stimulus parameters with minimal restriction of movement or distraction of the animal.     

Model study of the spread of electrotonic potential in cardiac tissue

This model study describes the electrotonic response of a cable model of cardiac tissue stimulated at one point. The stimulus is applied intracellularly in the form of a 2ms pulse of current of near threshold amplitude. The attenuation of the electrotonic potential with distance and its mode of propagation along the cable are compared for equivalent passive, continuous and discontinuous cables. The three structures have the same basic physical and electrical characteristic and they differ either with respect to being active or passive or to the presence or absence of intercellular gap junctions. In the continuous cable a just subthreshold stimulus produces a local active response which propagates more slowly and is attenuated less rapidly with distance than in a passive cable. The spatial decrement of the local response in a discontinuous cable is faster than in a continuous cable of equal average resistivity. It is suggested that the larger time constant of the foot of the action potential observed in the longitudinal direction in cardiac muscle could be due in part to the electrotonic spread of the local response from the site of stimulation.     

后路悬臂梁支撑线缆牵拉复位固定治疗齿状突骨折并寰枢椎脱位

目的 :探讨后路悬臂梁支撑线缆牵拉复位固定治疗齿状突骨折并寰枢椎脱位的临床疗效。方法 :回顾性分析2008年1月至2013年12月收治的12例齿状突骨折并寰枢椎脱位患者的临床资料,其中男8例,女4例;年龄21~53岁,平均37.2岁。11例为新鲜骨折脱位,1例为陈旧性骨折脱位,均为寰枢椎前脱位。依据Grauer改良的Anderson-D′Alonzo分型,ⅡA型3例,ⅡB型5例,ⅡC型3例,ⅢA型1例。所有病例行后路悬臂梁支撑线缆牵拉复位固定治疗。术后分别采用JOA评分和ADI测量对神经功能和寰枢椎脱位复位情况进行评估。结果:所有患者获得随访,时间6个月~2年,平均1年3个月。JOA评分术后1周、6个月及末次随访分别为13.2±1.3、13.5±1.4、14.3±1.5,较术前的8.3±1.4明显改善(P0.05)。术后X线及CT示寰枢椎前脱位均复位满意,术后1周、6个月及末次随访ADI分别为(2.2±0.4)、(2.4±0.6)、(2.3±0.5)mm,均较术前的(5.8±1.2)mm明显改善(P0.05)。内固定螺钉及线缆位置良好,无松动、断裂,寰枢椎后间隙植骨均融合。结论:后路悬臂梁支撑线缆牵拉复位固定治疗齿状突骨折并寰枢椎脱位是一种固定牢固、安全可靠的方法,可获得良好的临床效果。     

大型简易垃圾填埋场LFG横向迁移控制工程方案研究

结合深圳玉龙坑垃圾场封场工程,对简易垃圾填埋场LFG横向迁移的影响因素和控制措施进行了现场实验研究。研究结果表明,地质构造、地貌特征、土壤饱和度和地下构筑物等对LFG横向迁移的影响十分明显,如果采取适当的工程措施,将会有效提高气体防渗系统对LFG横向迁移的阻隔作用。     

tDCS possibly stimulates glial cells

Objective

Explore the possibility that transcranial direct current stimulation (tDCS) of the brain affects glial cells.

Methods

Cable theory is used to estimate roughly transmembrane potential in neurons and glial cells. tDCS is additionally compared to neuronal stimulation techniques for which the mechanisms are well known.

Results

Theoretical calculations indicated that tDCS can affect the glial transmembrane potential. The change is similar to what is physiologically observed in astrocytes during neuronal activation. In neurons, transmembrane potential changes are much weaker than the threshold for eliciting action potentials.

Conclusions

Based on simplified cable theory, tDCS may affect glial cells’ transmembrane potential and thereby the balance of neurotransmitters. No physiological evidence or proof is available, however.

Significance

It is an exciting possibility that tDCS could manipulate glial cells because they are active participants in brain function, and have multiple essential roles in the human brain. This approach may change greatly the therapeutic potential of tDCS, and also affects the safety considerations.     

Kirschner wire和Cable-pin在髌骨骨折手术治疗中的临床效果分析

目的分析比较Kirschner wire和Cable-pin在髌骨骨折治疗中的临床效果和应用价值。方法回顾2006年12月～2009年12月间笔者医院收治的107例髌骨骨折病人,分别用Kirschner wire和Cable—pin手术治疗68例和39例,记录两组病人的骨折类型、手术历时、术中出血量、住院日、医疗费用、术后并发症及远期膝关节功能恢复情况,应用SPSS11．0软件对观察指标进行统计学分析。结果107例病人全部获得随访,随访时间为3～21个月,平均14．2个月。Cable-pin治疗组患者的手术历时和术中出血量均明显少于Kirschner wire治疗组（P〈0．05）,但医疗费用远高于后者（P〈0．01）。两组病人术后并发症、住院日、骨折愈合时间和远期膝关节功能恢复情况无统计学差异。结论应用Kirschner wire手术治疗髌骨骨折更为广泛,方法灵活且疗效肯定,是一种性价比较高的治疗方法;Cable—pin操作简单、疗效可靠,但仅适用于横断性髌骨骨折,且医疗费用昂贵,在临床应用中有一定局限性。     

An inter-laboratory comparison study on transfer,persistence and recovery of DNA from cable ties

To address questions on the activity that led to the deposition of biological traces in a particular case, general information on the probabilities of transfer, persistence and recovery of cellular material in relevant scenarios is necessary. These figures may be derived from experimental data described in forensic literature when conditions relevant to the case were included. The experimental methodology regarding sampling, DNA extraction, DNA typing and profile interpretation that were used to generate these published data may differ from those applied in the case and thus the applicability of the literature data may be questioned. To assess the level of variability that different laboratories obtain when similar exhibits are analysed, we performed an inter-laboratory study between four partner laboratories. Five sets of 20 cable ties bound by different volunteers were distributed to the participating laboratories and sampled and processed according to the in-house protocols. Differences were found for the amount of retrieved DNA, as well as for the reportability and composition of the DNA profiles. These differences also resulted in different probabilities of transfer, persistence and recovery for each laboratory. Nevertheless, when applied to a case example, these differences resulted in similar assignments of weight of evidence given activity-level propositions.