Neural selectivity,efficiency, and dose equivalence in deep brain stimulation through pulse width tuning and segmented electrodes

BackgroundAchieving deep brain stimulation (DBS) dose equivalence is challenging, especially with pulse width tuning and directional contacts. Further, the precise effects of pulse width tuning are unknown, and recent reports of the effects of pulse width tuning on neural selectivity are at odds with classic biophysical studies.MethodsWe created multicompartment neuron models for two axon diameters and used finite element modeling to determine extracellular influence from standard and segmented electrodes. We analyzed axon activation profiles and calculated volumes of tissue activated.ResultsWe find that long pulse widths focus the stimulation effect on small, nearby fibers, suppressing distant white matter tract activation (responsible for some DBS side effects) and improving battery utilization when equivalent activation is maintained for small axons. Directional leads enable similar benefits to a greater degree. Reexamining previous reports of short pulse stimulation reducing side effects, we explore a possible alternate explanation: non-dose equivalent stimulation may have resulted in reduced spread of neural activation. Finally, using internal capsule avoidance as an example in the context of subthalamic stimulation, we present a patient-specific model to show how long pulse widths could help increase the biophysical therapeutic window.DiscussionWe find agreement with classic studies and predict that long pulse widths may focus the stimulation effect on small, nearby fibers and improve power consumption. While future pre-clinical and clinical work is necessary regarding pulse width tuning, it is clear that future studies must ensure dose equivalence, noting that energy- and charge-equivalent amplitudes do not result in equivalent spread of neural activation when changing pulse width.     

Effect of Day Optimizing Throughput (Dot) Knee Software Implementation on Magnetic Resonance Imaging Workflow Efficiency

PurposeAttempts by magnetic resonance (MR) manufacturers to help imaging centres improve patient throughput has led to the development of more automated acquisition. This software is capable of customizing individual scan alignment; potentially improving imaging efficiency and standardizing protocols. However, substantial investments are required to introduce such systems, potentially deterring their widespread application. This study assessed the implementation costs and reduction in examination durations for automated knee MR imaging (MRI) software.Materials and MethodsResearch activities were performed at a community-based academic centre on a 3-Tesla (3-T) system using Siemens' Day Optimizing Throughput (Dot) knee software. Examination acquisition times were extracted from the system before and after software implementation. Fiscal year 2012/13 finances were used to determine the average hourly cost of MRI utilization. Costs associated with automated software implementation were also calculated. Finally, the number of knee scans required to achieve a positive return on investment using the software was established.Results and DiscussionThe mean (standard deviation, sample size) pre- and post-Dot software scan times were 23.20 (4.18, n = 266) and 21.94 (4.51, n = 59) minutes, respectively, for a routine knee scan and 11.88 (1.60, n = 74) and 11.24 (1.51, n = 27) minutes, respectively, for a fast knee scan. The overall weighted average resulted in a 64-second time savings per automated knee examination. This negligible time savings would be extremely difficult to make use of clinically. Dot simplified 29 unique knee protocols to two, improving the consistency of knee examinations. Current Dot software is not compatible with all patients and therefore has limitations that are a concern among MR technologists.ConclusionAdoption of automated knee systems could assist in standardizing protocols; however, the cost of implementation and difficulty in modifying patient scheduling to reflect the minimal time savings would make a financial return unlikely to occur at small- and medium-sized institutions.     

他克莫司联合308nm准分子激光治疗面部白癜风

目的探讨他克莫司联合308nm准分子激光在面部白癜风治疗中的应用效果。方法选取2017年2月-2019年2月医院84例面部白癜风患者为研究对象,根据入院单双号将受试者进行分组,其中对照组42例患者接受308nm准分子激光治疗,研究组42例患者在对照组的基础上联合他克莫司软膏治疗,比较两组患者治疗后1个月、3个月时的治疗总有效率以及治疗前后白斑面积与皮损区IL-17水平变化。结果研究组患者在治疗后1个月、3个月时的治疗总有效率均显著高于对照组(P<0.05),与治疗前相比,治疗后两组患者白斑面积及皮损区IL-17水平均显著减少,且研究组显著少于对照组(P<0.05)。结论他克莫司联合308nm准分子激光可有效缩小白斑面积,降低皮损区IL-17水平,疗效确切。     

PS联合CPAP治疗新生儿呼吸窘迫综合征临床研究

目的通过研究肺表面活性物质(PS)结合持续气道正压通气(CPAP)治疗新生儿呼吸窘迫综合征(NRDS)的治疗效果,进一步指导NRDS的临床治疗。方法选取于2017年4月-2018年10月间在本院收治的80例确诊为新生儿呼吸窘迫综合征的患儿作为研究对象,随机将患儿分为试验组和对照组,对照组给予持续气道正压通气治疗,试验组在对照组的基础上联合使用PS治疗。结果试验组对于呼吸窘迫缓解的有效率明显高于对照组,在气管插管内滴入PS治疗后试验组的血气情况明显优于对照组,且试验组患儿副作用发生率明显低于对照组,以上指标差异具有统计学意义,P <0.05。结论 PS结合CPAP在新生儿呼吸窘迫综合征的治疗中疗效很好。     

基于超效率DEA的天津市基本公共卫生配置资源效率研究

评价天津市各辖区基本公共卫生服务的资源配置效率,寻求有效的资源配置措施和方法,为进一步优化卫生资源配置提供参考依据。方法利用数据包络分析,对天津市16辖区的基本公共卫生服务进行效率评价。结果天津市基本公共卫生服务的资源配置效率整体不高,仅有5辖区达到了规模最优,多数区非DEA有效,且投入过剩与产出不足并存。结论为了达到最优的基本公共卫生服务效率,政府及各级基本公共卫生服务机构必须有效地完善、落实相关政策,优化资源投入结构,统筹地区差异,加强资源供给管理,提高资源利用效率。     

Characterizing luminous efficiency functions for a simulated mesopic night driving task based on reaction time

The objective of this study is to test the luminous efficiency functions V(lambda), V'(lambda), V(10)(lambda) and their linear combinations on the basis of a data set gained from a simulated mesopic night-time driving experiment. Another aim is to provide 'real-world' data for the 'X framework' or 'linear combination model', and to find out its limits in a practical situation. Human performance was measured by the reaction time method. Results show that the single parameter of the linear combination of photopic and scotopic luminous efficiency functions can be determined analytically with little variation for a given mesopic background luminance level and a given visual target colour, but the computation leads to considerable deviations comparing all three target colours (red, green and blue) used in the experiment. The conclusion for the given experimental conditions is that the single parameter of the linear combination model has an increasing deviation for lower background luminance levels.     

重组腺相关病毒-阳离子脂质体载体的构建及评价

目的探讨重组腺病毒相关病毒（rAAV）-阳离子脂质体（LyoVec）复合载体的构建方法及其转染率评价。方法构建rAAv～GFP，rAAv—LyoVec复合载体及rAAV—GFP—LyoVec。倒置荧光显微镜观察，测定rAAV—GFP，LyoVec—GFP及rAAV—GFP-LyroVec对定量C6细胞的转染率，筛选出高转染率载体。结果rAAV—GFP组24、48、72和96h转染率分别为16％、23％、21％和9％；LyoVec-GFP组为28．5％、33％、32％和11％；rAAV—GFP—Lyovec组为49％、59％、64％和20％。rAAV-GFP—LyoVec纽分别在24、48、72和96h的转染率显著高于rAAV—GFP组（P〈0．01）及LyoVec—GFP组（P〈0．01）。结论新构建rAAV—LyoVec复合载体基因的转染效率远远高于rAAV或LyoVec独立转染。     

Working‐correlation‐structure identification in generalized estimating equations

Selecting an appropriate working correlation structure is pertinent to clustered data analysis using generalized estimating equations (GEE) because an inappropriate choice will lead to inefficient parameter estimation. We investigate the well‐known criterion of QIC for selecting a working correlation structure, and have found that performance of the QIC is deteriorated by a term that is theoretically independent of the correlation structures but has to be estimated with an error. This leads us to propose a correlation information criterion (CIC) that substantially improves the QIC performance. Extensive simulation studies indicate that the CIC has remarkable improvement in selecting the correct correlation structures. We also illustrate our findings using a data set from the Madras Longitudinal Schizophrenia Study. Copyright © 2008 John Wiley & Sons, Ltd.     

应用无死腔气管插管提高正常和急性肺损伤兔的机械通气效率

目的：观察无死腔气管插管能否提高急性呼吸衰竭常规机械通气的效果。方法：应用一种新型无死腔气管插管和普通聚氯乙烯气管插管对正常和急性肺损伤兔进行常规通气，对两种气管插管的肺气体交换和气道内气体动力学及血流动力学变化进行比较。无死腔气管插管用２根Ｐｏｔｅｘ气管插管远端３ｃｍ处纵切后对粘而成。５只新西兰成年兔，麻醉下气管切开，在持续应用潘龙阻断自主呼吸条件下，随机用新型气管插管和普通气管插管Ｓｅｒｖｏ９００Ｃ进行机械通气，每次持续３０分钟，测定并记录动脉血压、气道压力、血流动力学参数和呼气末ＣＯ２浓度。结果：在正常肺和急性肺损伤条件下，新型气管插管可使所有动物的ＰａＣＯ２和生理死腔／潮气量（ＶＤ／ＶＴ）下降，ＰａＣＯ２分别下降１．４０±０．２０ｋＰａ（１ｋＰａ＝７．５ｍｍＨｇ）和１．６０±０．３０ｋＰａ（Ｐ＜０．０１），ＶＤ／ＶＴ分别下降０．１３±０．０２和０．１５±０．０４（Ｐ＜０．０１）；ＰａＯ２、气道压力和血流动力学无显著变化。结论：无死腔气管插管可明显提高常规机械通气效率。     

The effects of altering time delays of coupled pacing during acute atrial fibrillation

BACKGROUND: Coupled pacing (CP), which consists of delivering a premature electrical stimulation to the heart after the effective refractory period of ventricular activation, is a novel method for controlling ventricular rate during atrial fibrillation (AF). It also has been established that CP improves pump function by enhancing external cardiac work and myocardial efficiency. OBJECTIVE: The purpose of the present study was to determine if two time delays for CP (short and long) would result in similar improvements in ventricular function. METHODS: In a canine model, we applied CP at two time delays (CP-S and CP-L) during two stages: sinus rhythm (SR) and acute AF. The cardiac responses to CP during SR served as the nontachycardic and nondepressed control. During both rhythms, we shortened the coupling interval until we obtained maximal contractility, designated CP-S. Next, we increased the delay until we started to see a measurable secondary contraction (left ventricular pressure development of approximately 20 mmHg). These longer delays were designated CP-L. RESULTS: Our results showed that the ventricular rate of intrinsic activation (VRIA) remained decreased despite prolongation of the time delay of CP during both AF and SR. Also, both delays of CP increased left ventricular systolic pressure (LVSP) and dLVP/dt, which are indices of myocardial contractility. In contrast, CP increased external cardiac work only during AF. Prolonging this time delay did not markedly decrease the improvement in external cardiac work. Myocardial O(2) consumption (MVO(2)) did not significantly change as the result of CP during either SR or AF. Finally, myocardial efficiency improved during AF as the result of CP at both time delays. CONCLUSIONS: In conclusion, shorter time delays for CP increased contractile strength during both SR and AF. However, extending the time delay of CP had minimal effects on diminishing the improved ventricular pump function and energetics that resulted from CP during AF. Thus, the maximal enhancement of myocardial contractility via CP-S was not needed to maintain the improved ventricular function during acute AF when CP is applied.