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.     

Coronary Artery Lumen Segmentation Using Location–Adaptive Threshold in Coronary Computed Tomographic Angiography: A Proof-of-Concept

ObjectiveTo compare the lumen parameters measured by the location-adaptive threshold method (LATM), in which the inter- and intra-scan attenuation variabilities of coronary computed tomographic angiography (CCTA) were corrected, and the scan-adaptive threshold method (SATM), in which only the inter-scan variability was corrected, with the reference standard measurement by intravascular ultrasonography (IVUS).Materials and MethodsThe Hounsfield unit (HU) values of whole voxels and the centerline in each of the cross-sections of the 22 target coronary artery segments were obtained from 15 patients between March 2009 and June 2010, in addition to the corresponding voxel size. Lumen volume was calculated mathematically as the voxel volume multiplied by the number of voxels with HU within a given range, defined as the lumen for each method, and compared with the IVUS-derived reference standard. Subgroup analysis of the lumen area was performed to investigate the effect of lumen size on the studied methods. Bland-Altman plots were used to evaluate the agreement between the measurements.ResultsLumen volumes measured by SATM was significantly smaller than that measured by IVUS (mean difference, 14.6 mm³; 95% confidence interval [CI], 4.9–24.3 mm³); the lumen volumes measured by LATM and IVUS were not significantly different (mean difference, −0.7 mm³; 95% CI, −9.1–7.7 mm³). The lumen area measured by SATM was significantly smaller than that measured by LATM in the smaller lumen area group (mean of difference, 1.07 mm²; 95% CI, 0.89–1.25 mm²) but not in the larger lumen area group (mean of difference, −0.07 mm²; 95% CI, −0.22–0.08 mm²). In the smaller lumen group, the mean difference was lower in the Bland-Altman plot of IVUS and LATM (0.46 mm²; 95% CI, 0.27–0.65 mm²) than in that of IVUS and SATM (1.53 mm²; 95% CI, 1.27–1.79 mm²).ConclusionSATM underestimated the lumen parameters for computed lumen segmentation in CCTA, and this may be overcome by using LATM.     

牙冠延长术在残根残冠修复中的临床疗效

目的评价牙冠延长术在牙体缺损达龈下的残根残冠修复中的临床疗效。方法自2004年5月至2005年6月,对32例患者的36颗牙体缺损达龈下的患牙,术前按断端位于龈下最深距离分为A组(20颗患牙,距离<3.0mm)和B组(16颗患牙,3.0mm≤距离≤4.0mm),均采用牙冠延长术暴露龈下牙体断面,术后6周行桩冠修复。分别记录和比较手术前、后牙周探诊深度(PD)、菌斑指数(PLI)、龈沟出血指数(SBI)和牙齿松动度,以观察临床疗效。结果术后随访患者6个月,两组病例术后6周牙体断端均暴露较好、龈缘颜色正常,术后修复效果有效率为100%,满意率为77.78%。A组术后无松动,修复效果满意;B组术后50.00%出现Ⅰ度松动,修复效果欠佳,两组修复效果比较差异有显著意义(P<0.05)。术后各阶段两组的PD、PLI、SBI均明显优于术前(P<0.05),但两组术后牙周指数比较差异无显著意义(P>0.05)。结论牙冠延长术有利于残根残冠的保存和修复,但要注意适应证的选择。     

线宽增量法及其在生物材料发射光谱分析中的应用

作者利用交流电弧和光栅摄谱仪组装了能够绘制谱线轮廓曲线和准确测定谱线宽度的记录仪,用线宽增量法对生物材料(拟血清)中的主要成分Ca和微量元素Cu进行了测定。与黑度法相比,本实验结果的线性好,误差小,再现性有所提高。这些结果表明,用上述仪器装置和线宽增量法进行生物材料含量分析优于黑度法。     

两脚和四脚快速腭扩张器疗效的比较研究

目的:本研究比较了两脚和四脚腭快速扩张器在打开腭中缝和牙齿扩张的效果.方法:本研究包括30例患者,随机分配在两脚扩张器组和四脚扩张器组,在扩张器戴入前,扩弓结束后和扩张器拆除时,拍摄标准咬合片和采取上颌模型,并对测量数据进行统计分析.结果:研究发现两组间的磨牙尖宽度、磨牙龈宽度、尖牙尖宽度、尖牙龈宽度和中切牙间裂隙间没有统计学差异;在牙弓的周长和腭中缝打开上略有差异.结论:两脚扩张器和四脚扩张器对腭中缝和牙列的作用相同.     

Patients seeking symmetrical recontouring for “Perceived” deformities in the width of the face and skull

This article describes plastic surgery patients who sought symmetrical recontouring of the width of the face and skull. The basic demographic and personality characteristics of these facial width deformity (FWD) patients and the surgical procedures performed on them are discussed. Details of the surgical and psychological management of three representative cases are given. Speculative conclusions regarding the general characteristics of the FWD population are offered. Suggestions are proposed for a combined surgical-medical psychotherapeutic collaboration in managing these patients.     

EEG asymmetries may be affected by cranial and Brain parenchymal asymmetries

Summary The plagiocephaly index, an index that reflects an underlying anatomic asymmetry of the brain, was assessed in ten schizophrenic patients and its values were correlated with the lateral distribution of quantitatively evaluated EEG. The correlations between the index and alpha power at F7 were significant, positive for frontal asymmetry (frontal bulging) and negative for occipital flattening. We then studied ten normal subjects in an attempt to illuminate the contribution of several cephalic and cranial variables to the imbalance of alpha-afterdischarges (AD) of VEP recorded at O1–O2. The asymmetry index of AD was computed and correlated with asymmetries of CT-derived measures of occipital bone thickness, occipital lobe width, mastoid area, and sulcal asymmetry (the asymmetry of intraparietal sulcus location from the longitudinal fissure). With the exception of the sulcal variable all measures significantly covaried with alpha AD. These findings caution that it may be important to determine cranial and brain parenchymal asymmetries where brain laterality is pertinent to studies of EEG.     

Characterization of a monoclonal anti-Bw4 antibody (Tü109): Evidence for similar epitopes on the Bw4 and Bw6 antigens

The production and serologic, as well as immunochemical properties of a cytotoxic murine IgG monoclonal antibody (Tü109) that precipitates HLA-class I molecules, are described. In the microcytotoxicity assay Tü109 supernatant was demonstrated on a panel of 424 HLA-ABC, -DR, -DQ, -MT typed normal Caucasian blood donors to define an epitope on HLA-B locus molecules in great association with the supertypic specificity Bw4. Reactivity of supernatant showed MHC linked inheritance of the Tü109 determinant and discriminated the HLA-Bw4/Bw6 associated HLA-B locus split antigens. Weak or lack of binding on lymphocytes from some HLA-Bw4 heterozygous individuals, particularly typing for HLA-Bw44, appeared to be due to qualitative and/or quantitative variations of HLA-B locus molecules on the cell surface. With Tü109 ascites fluid, however, extra-reactivity on all HLA-Bw6⁺ cells was demonstrated. Preferential binding of supernatant to HLA-Bw4, but reactivity of ascites fluid with HLA-Bw6⁺ molecules in addition, was furthermore confirmed by IEF analysis of antigens immunoprecipitated with Tü109 from cell lysates. Thus the antibody may help to analyze the evolutionary relationship of the diallelic specificities Bw4 and Bw6.     

Computerized Digital Imaging Techniques Provided by Digital X-ray Radiogrammetry as New Diagnostic Tool in Rheumatoid Arthritis

Purpose Our study evaluates digital x-ray radiogrammetry (DXR) and Radiogrammetry Kit (RK) as a new diagnostic method for the measurement of disease-related osteoporosis including quantification of joint space narrowing dependent on the severity of rheumatoid arthritis (RA). Materials and Methods A total of 172 unselected patients with RA underwent computerized measurements of bone mineral density (BMD) and metacarpal index (MCI) by DXR, as well as a semiautomated measurement of joint space distances at the metacarpal–phalangeal articulation (JSD-MCP 2–5), both were analyzed from plain radiographs of the nondominant hand. Results Correlations between DXR-BMD and DXR-MCI vs. parameters of RK were all significant (0.34 < R < 0.61; p < 0.01). An expected negative association was observed between RK parameters and the different scoring methods (−0.27 < R < −0.59). The maximum relative decrease in BMD vs. MCI as measured by DXR between the highest and lowest RA severity group was −27.7% vs. −27.5% (p < 0.01) for the modified Larsen Score, whereas the minimal value of relative DXR-BMD and DXR-MCI reduction could be documented for the Sharp Erosion Score (−20.8% vs. −26.8%; p < 0.01). The relative reduction of mean JSD-MCP using RK significantly varied from −25.0% (Sharp Erosion Score) to −41.2% (modified Larsen Score). In addition, an excellent reproducibility of DXR and RK could be verified. Conclusion DXR in combination with RK could be a promising, widely available diagnostic tool to supplement the different scoring methods of RA with quantitative data, allowing an earlier and improved diagnosis and more precision in determining disease progression.     

一种脉象全信息触力传感器

根据中医脉象生理信号的采集原理和特点,结合国际标准脉搏波触力传感器ISO 19614:2017-05的要求,研制了一种可将脉象生理信号进行完整客观化采集的专用触力传感器组件,并符合产业化要求。该传感器可采集人体寸口部位的脉象幅度和宽度信号,能同时进行三部九候的脉象采集。对该传感器经验证后,其相关技术性能指标的检测结果符合国际标准规定的相关要求,并与临床中医专家的诊断结果一致性为92.3%。