Comparing limb proprioception and oculomotor signals during hand-guided saccades

We previously showed that saccades tend to overshoot briefly flashed targets that were manually displaced in the dark (Ren et al. 2006). However it was not clear if the overshoot originated from a sensory error in measuring hand displacement or from a premotor error in saccade programming, because gaze and hand position started at the same central position. Here, we tested between these hypotheses by dissociating the initial eye and hand position. Five hand/target positions (center, far, near, right, left) on a frontally-placed horizontal surface were used in four paradigms: Center or Peripheral Eye-hand Association (CA or PA, both gaze and right hand started from the center or a same peripheral location) and Hand or Eye Dissociation (HD or ED, hand or gaze started from one of three non-target peripheral locations). Subjects never received any visual feedback about the final target location and the subjects’ hand displacement. In the CA paradigm, subjects showed the same overshoot that we showed previously. However, changing both initial eye and hand positions relative to the final target (PA) affected the pattern, significantly altering the directions of overshoots. Changing only the initial position of hand (HD) did not have this effect, whereas changing only initial eye position (ED) had the same effect as the PA condition (CA ≈ HD, PA ≈ ED). Furthermore, multiple regression analysis showed that the direction of the ideal saccade contributed significantly to the endpoint direction error, not the direction of the hand path. These results suggest that these errors do not primarily arise from misestimates of the hand trajectory, but rather from a process of comparing the initial eye position and the limb proprioceptive signal during saccade programming.     

Biomechanical analysis of cervical spine sagittal stiffness characteristics

The orientation of the loading, along which the minimum and maximum displacements occur, can be described as the principal axis. This work presents a model to determine extremums of the compliance of the cervical spine and corresponding principal axis, given the pose and flexibility of each functional cervical unit. As the cervical model of C(2)-C(7) section is flexed, it becomes tensionally stiffer and as the structure is extended, it becomes compressively stiffer. The opposite is true for the model including the atlanto-occipito-axial complex suggesting a compressively stiffer column as it is flexed and a tensionally stiffer structure as it is extended.     

On the Production of Chitosan-Coated Polycaprolactone Nanoparticles in a Confined Impinging Jet Reactor

This work is focused on the synthesis of polycaprolactone nanoparticles, coated with chitosan, in a confined impinging jet reactor using the solvent displacement method. The role of the various reacting species was investigated, evidencing that a biocompatible polymer, for example, polycaprolactone, is required to support chitosan to obtain a monomodal particle size distribution, with low particle diameters. A surfactant is required to reduce the nanoparticle size (down to a mean diameter of about 260 nm) and obtain a positive zeta potential (about +31 mV), perfectly suitable for pharmaceutical applications. Different surfactants were tested, and Poloxamer 388 appeared to be preferable to polyvinyl alcohol. The effect of the concentration of Poloxamer 388 (in the range 0.5-5 mg mL^?1) and of chitosan (in the range 1.5-5 mg mL^?1) on both the mean particle size and zeta potential was also investigated, evidencing that chitosan concentration has the strongest effect on both parameters. Finally, the effect of solvent evaporation, quenching and feed flow rate was investigated, showing that the evaporation stage does not affect particle characteristics, quenching is required to avoid particle aggregation, and a minimum liquid flow rate of 80 mL min^?1 is required in the considered reactor to minimize the particle size.     

Influence of altered occlusal guidance on masticatory muscle activity during clenching

This study investigated the influence of experimentally altered occlusal guidance on masticatory muscle activity. Twenty healthy human subjects (15 males and five females with an average age of 26.5 years) volunteered to participate in this study. Metallic occlusal overlays were fabricated for the lower working side canine and overlaid on the second molar and the non-working side second molar to simulate a canine-protected occlusion, group function occlusion and bilateral balanced occlusion. Electromyography (EMG) activities in the bilateral masseter, anterior and posterior temporalis were recorded during maximal clenching. The experimental occlusal pattern revealed to have statistically significant effects on EMG activity. As the most characteristic change, EMG activity in the anterior temporalis significantly increased in the simulated group function occlusion and the simulated bilateral balanced occlusion compared with the simulated cuspid protected occlusion. The increased teeth contacts to the posterior region altered the unilateral pattern of the anterior temporalis activity to the bilateral pattern, while that of masseter activity remained unchanged.     

Multiple displacement amplification as an aid in checkerboard DNA-DNA hybridization

OBJECTIVE: The study aimed to determine if multiple displacement amplification could be used to provide abundant target DNA and DNA probes for checkerboard DNA-DNA hybridization. METHODS: Multiple displacement amplification was used to amplify 1 and 10 ng DNA from 16 individual bacterial species, DNA from single colonies, from a mixture of 20 bacterial species and oral biofilm samples, such as supragingival plaque, subgingival plaque, buccal swab and root canal samples. Samples in reaction buffer were heat-denatured at 95 degrees C for 3 min and cooled to 4 degrees C. Phi29 DNA polymerase was added and the mixture was incubated at 30 degrees C for 16-18 h. The quantity of the product was evaluated by the Picogreen assay. The amplified material was labeled with digoxigenin. The probes were compared with probes obtained from unamplified DNA using checkerboard DNA-DNA hybridization. Both amplified DNA and unamplified DNA were used as targets on the membrane. Amplified oral biofilm samples were compared to unamplified samples using checkerboard DNA-DNA hybridization. RESULTS: The DNA yield ranged from 4 to 11 microg. DNA-DNA hybridization showed that the amplified genome of each species used either as target or as probe provided signals equivalent to controls and that amplification of a mixture of species provided signals comparable to those provided by the unamplified source mixture. Amplified oral biofilm samples exhibited comparable proportions of bacterial DNA when compared to the original unamplified samples. CONCLUSIONS: The multiple displacement amplification technique is a simple and reliable method to uniformly amplify DNA for use in checkerboard DNA-DNA hybridization. It is also a useful tool in the amplification of clinical samples.     

胶原酶治疗腰椎间盘突出症文献计量 与可视化分析

目的 通过CiteSpace软件分析国内胶原酶治疗腰椎间盘突出症的研究历史和现状。方法 检索1984年至2022年中国知网（CNKI）数据库中关于胶原酶治疗腰椎间盘突出症的文献,应用CiteSpace5.8.R3软件建立可视化科学知识图谱。结果 纳入符合主题的文献1022篇,1994年后发文量逐渐增长,在2005年和2006年年发文量达到最高;发文量排名前3的作者是刘延青、王执民、宋文阁;发文排名前2的省份是山东省和广东省;排名前4的关键词聚类标签是“#0 胶原酶,#1 盘内注射,#2 靶点,#3 臭氧”,关键词突现分析表明“臭氧”具有最大突现强度,“等离子、射频热凝、靶点”突现强度持续至2022年;胶原酶治疗腰椎间盘突出症相关研究经历了持续增长、相对稳定、逐年下降3个阶段;胶原酶的注射方式曾是研究重点,近些年研究热点集中于胶原酶的联合治疗。结论 胶原酶在老年或者难治性腰椎间盘突出症中仍具有研究价值,胶原酶与其他微创介入联合治疗是今后研究热点。     

The effectiveness of adding guided growth to soft tissue release in treating spastic hip displacement

BackgroundGuided growth at the proximal femur using one transphyseal screw corrects coxa valga and improves hip displacement in cerebral palsy. This study aimed to validate the effects of adding guided growth (GG) to soft tissue release (STR), in terms of decreasing the migration percentage (MP), compared to those with soft tissue alone.MethodsThis retrospective study comprised patients with cerebral palsy who underwent soft tissue release alone (Group STR) or soft tissue release plus guided growth (Group GG) for hip displacement (mean age, 8.1 years; mean follow-up, 4.9 years). Difference in the MP and rate of controlling MP <40% at 2 years postoperatively and rate of revision surgeries at 5 years postoperatively were compared between the groups.ResultsThe two groups were comparable in age, side, and gross motor function level, but Group GG (n = 24) had more severe hip displacement preoperatively than did Group STR (n = 64). Group GG had a significantly greater 2-year decrease in the MP (?14.8% vs. ?11.8%, p < 0.05) than did Group STR. Among patients with a pre-operative MP >50%, the rate of MP <40% was greater in Group GG (73%) than in Group STR (41%). Revision surgeries, mainly repeated guided growth and soft tissue release, were comparable between the groups.ConclusionsThis is the first comparative study to support adding guided growth to soft tissue release, as it results in greater improvements in hip displacement than that with soft tissue release alone. Non-ambulatory patients or severe hip displacement with MP 50%–70% could benefit from this less aggressive surgery by controlling the MP under 40% without femoral osteotomy.     

非洲人腰椎间盘突出术后复发原因与治疗

目的：探讨非洲人LDH（Lumbar Disc Herniated）术后复发的原因及再次治疗的最佳方法。方法：采用骶管硬膜外前间隙介入注射利得合剂（A组）和休息＋口服消炎镇痛药物（B组）治疗LDH术后复发，运用统计学分析，并进行对比研究，根据Prolo腰椎术后评定标准，对全都复发病例（56例）进行了3～9个月的随访。结果：A组30例中，8～10分11例，6～7分15例，〈5分4例；B组26例中，8～10分6例，6～7分12例，〈5分8例。两组结果经统计学比较差别有显著性（P〈0．05）。结论：非洲人LDH术后复发的原因也是多方面的，骶管硬膜外前间隙介入注射利得合荆也是一种行之有效的治疗方法。     

混合现实技术引导的经皮内窥镜下腰椎椎间盘切除术的初步探索与应用

经皮内窥镜下腰椎椎间盘切除术（PELD）已经成为治疗腰椎椎间盘突出症（LDH）的首选方法^［1-3］。腰椎椎间盘突出类型多样化,术前须精确定位突出椎间盘的“靶点”位置,确定进针点、深度和角度等相关参数,以便术中可按照术前设计快速准确地穿刺和置入工作通道,这是靶向穿刺技术的核心,也是尽可能减少不必要创伤并发症的基础^［4］。常规手术通道的建立,需要根据椎间盘突出的不同病理类型并结合临床实践确定,且术中需要C形臂X线机透视辅助,存在学习曲线陡峭、辐射量大、手术风险高等问题^［5-6］。混合现实（MR）技术是近年发展起来的一门新兴技术,其将虚拟现实（VR）技术与增强现实（AR）技术相结合,操作者可从MR技术呈现的全息影像中获取相关信息,从而实现虚拟和真实的交互^［7-8］。目前,MR技术在复杂的脑外科手术、髋关节手术中已有应用,并获得良好的临床疗效^［9-11］,但尚无其应用于PELD的报道。本研究组在MR技术引导下,对1例LDH患者行PELD,取得了良好的临床疗效,现报告如下。     

对Garden指数作为股骨颈骨折复位质量评价标准的再认识

目的探讨Garden指数能否判断股骨颈骨折的旋转移位。方法取5具10侧健康股骨近端尸体标本,男3具,女2具;死亡年龄为45~70岁。于股骨头中心置入1枚直径为2.0 mm的克氏针,垂直于股骨颈中部截骨,在截骨处远端骨面标明旋转角度。在每侧标本上依次进行旋前及旋后0°、10°、20°、30°、40°、50°、70°、90°操作,并摄标本正、侧位X线片,利用影像归档和通信系统测量Garden指数,比较不同旋转角度下的正位、侧位Garden指数。同时观察在不同旋转角度下股骨头小凹面积的变化规律。结果从0°至旋前30°或旋后30°的过程中,正位、侧位Garden指数无明显变化,差异均无统计学意义(P>0.05),且数值均>155°。从旋前40°至旋前90°的过程中,正位Garden指数分别为152.36°±1.41°、146.04°±1.64°、143.95°±0.60°、141.73°±0.60°,侧位Garden指数分别为172.54°±0.86°、168.57°±0.98°、157.18°±1.17°、156.47°±1.63°,不同旋转角度之间比较差异均有统计学意义(P<0.05)。从旋后40°至旋后90°的过程中,正位Garden指数分别为151.67°±1.06°、147.32°±1.82°、142.77°±0.75°、139.88°±1.48°,侧位Garden指数分别为172.28°±0.79°、166.76°±1.02°、155.67°±1.74°、154.16°±1.27°,不同旋转角度之间比较差异均有统计学意义(P<0.05)。随着旋前角度的增大,股骨头小凹面积逐渐减少;随着旋后角度的增大,股骨头小凹面积逐渐增大。结论在0°~30°的旋前或旋后范围内,Garden指数无法准确判断股骨颈骨折复位时的旋转移位。股骨头小凹面积的变化可以辅助判断股骨颈骨折的旋转移位。