衍生化-毛细管气相色谱法同时测定糖尿病大鼠坐骨神经中葡萄糖、山梨醇、肌醇

建立了大鼠坐骨神经中糖醇化合物葡萄糖、山梨醇、肌醇同时测定的毛细管气相色谱分析方法。选择甘露糖为内标,先加入盐酸羟胺吡啶溶液进行肟化反应,再加入乙酸酐溶液进行乙酰化反应,将葡萄糖、山梨醇、肌醇转化成糖腈乙酰酯化合物,经SE 30毛细管柱色谱分离,氢火焰离子化检测器检测。葡萄糖、山梨醇、肌醇的回收率均在93%以上,其检出限分别为0.40、0 30、0.26ng/μL。对比测定了正常对照组、糖尿病组、某中药复方治疗组大鼠坐骨神经中以上3种糖醇含量。     

Preparation of HMWCNT/PLLA nanocomposite scaffolds for application in nerve tissue engineering and evaluation of their physical,mechanical and cellular activity properties

This study was aimed to prepare biodegradable and porous nanocomposite scaffolds with microtubular orientation structure as a model for nerve tissue engineering by thermally induced phase separation (TIPS) method using dioxane as the solvent, crystalline poly (L‐lactic acid) (PLLA) and multi‐walled carbon nanotubes (MWCNTs). In order to overcome dispersion of MWCNTs in the PLLA matrix, heparinization of MWCNTs was performed. Solvent crystallization, oriented structure, the mean pore diameter and porosity percentage of the scaffolds were controlled by fundamental system parameters including temperature‐gradient of the system, polymer solution concentration and carbon nanotube content. Scanning Electron Microscopy (SEM), ImageJ, software and dynamic mechanical thermal analysis (DMTA) were used to investigate the structural and mechanical properties. TEM observation was carried out for characterization of nanotube dispersion in PLLA. It was found that the scaffolds containing heparinized multi‐walled carbon nanotubes (HMWCNTs) exhibited higher storage modulus, better carbon nanotube (CNT) dispersion and tubular orientation structure than those with non heparinized MWCNTs. In‐vitro studies were also conducted by using murine P₁₉ cell line as a suitable model system to analyze neuronal differentiation over a 2‐week period. Immunofluorescence and DAPI staining were used to confirm the cells' attachment and differentiation on the PLLA/HMWCNT nanocomposite scaffolds. Based on the results, we can conclude that the PLLA/HMWCNT scaffolds enhanced the nerve cell differentiation and proliferation, and therefore, acted as a positive cue to support neurite outgrowth. Copyright © 2015 John Wiley & Sons, Ltd.     

红外热不对称分析用于面神经功能损伤的客观评估

健康人体的温度分布存在一种双侧对称性,当面神经功能受损时,将改变这种热分布的对称性。人体热量大多通过红外辐射的形式散发,因此利用红外热成像技术可以有效捕捉这种红外热辐射分布的改变。本文提出一种新的热不对称分析的方法——有效热面积比,即计算面部特定区域与对侧区域的温差乘以温度异常区面积与总面积之比。利用这种方法对面神经功能损伤的患者和健康人群作对照性试验,结果显示:此方法的特异性和敏感性平均为0.90和0.87,比常规方法提高了7%和26%,有效热面积比与面神经功能的损伤程度正相关,平均为0.664。因此,关于诊断和评估面神经功能,红外热成像是一种有力的工具,有效热面积比是一项高效的临床指标。     

Amperometric Biosensor for Evaluation of Competitive Cholinesterase Inhibition by the Reactivator HI‐6

Abstract

Amperometric biosensors containing enzymes butyrylcholinesterase or acetylcholinesterase were prepared. The biosensors were employed for studying of cholinesterase reactivator: HI‐6. Competitions between HI‐6 and acetylthiocholine as enzyme substrate were used for determination of IC₅₀ value. Biosensors with butyrylcholinesterase from human serum determined IC₅₀ as (1.00±0.02)×10^?6 M; the biosensor with acetylcholinesterase from human erythrocytes performance provided IC₅₀ (3.31±0.13)×10^?6 M, the one with human recombinant acetylcholinesterase (2.00±0.06)×10^?6 M and finally biosensor with acetylcholinesterase from electric eel (6.17±0.17)×10^?6 M when 5 mM acetylthiocholine as substrate was used. We are encouraged to consider presented biosensors as a very useful for evaluation of newly prepared cholinesterase reactivators.     

家鸽头部的磁性物质

磁铁矿可以在很多生物组织中被发现,国外研究者同样在家鸽上喙皮肤组织中发现了规则分布的超顺磁磁铁矿颗粒。他们应用透射电子显微镜确认了这些小磁铁矿晶体为尺寸在1—5 nm 的聚集体,集中存在于皮下组织中。这些超顺磁粒子聚集体又形成直径为1—3 μm的粒子束,分布在大细胞之间的长形结构中,并且与神经组织紧密相连。应用光学显微镜和电子显微镜,国外研究者也对家鸽上喙传入三叉神经末梢的次细胞组织进行了研究。这些神经末梢组织直径大约5 μm,内部包含着聚集成束的超顺磁磁铁矿颗粒。大约10到15个粒子束存在于一个神经末梢中,沿着细胞膜排列。每一个超顺磁粒子束包埋在一个纤维杯中,口朝向细胞表面,通过纤维组织,这些粒子束粘附在细胞表面上。除了超顺磁颗粒,非晶态铁磷酸盐也被发现,它们沿着神经末梢的纤维中心分布。解剖特征表明,这些神经末端可以探测很小的地磁场强度的变化,考虑到以超顺磁磁铁矿颗粒为基础的“磁接收器”理论,他们还给出了几个“磁接收器”的模型。     

Polymer Scaffolds for Biomedical Applications in Peripheral Nerve Reconstruction

The nervous system is a significant part of the human body, and peripheral nerve injury caused by trauma can cause various functional disorders. When the broken end defect is large and cannot be repaired by direct suture, small gap sutures of nerve conduits can effectively replace nerve transplantation and avoid the side effect of donor area disorders. There are many choices for nerve conduits, and natural materials and synthetic polymers have their advantages. Among them, the nerve scaffold should meet the requirements of good degradability, biocompatibility, promoting axon growth, supporting axon expansion and regeneration, and higher cell adhesion. Polymer biological scaffolds can change some shortcomings of raw materials by using electrospinning filling technology and surface modification technology to make them more suitable for nerve regeneration. Therefore, polymer scaffolds have a substantial prospect in the field of biomedicine in future. This paper reviews the application of nerve conduits in the field of repairing peripheral nerve injury, and we discuss the latest progress of materials and fabrication techniques of these polymer scaffolds.     

Methylcobalamin‐Loaded PLCL Conduits Facilitate the Peripheral Nerve Regeneration

The feasible fabrication of nerve guidance conduits (NGCs) with good biological performance is important for translation in clinics. In this study, poly(d ,l ‐lactide‐co‐caprolactone) (PLCL) films loaded with various amounts (wt; 5%, 15%, 25%) of methylcobalamin (MeCbl) are prepared, and are further rolled and sutured to obtain MeCbl‐loaded NGCs. The MeCbl can be released in a sustainable manner up to 21 days. The proliferation and elongation of Schwann cells, and the proliferation of Neuro2a cells are enhanced on these MeCbl‐loaded films. The MeCbl‐loaded NGCs are implanted into rats to induce the regeneration of 10 mm amputated sciatic nerve defects, showing the ability to facilitate the recovery of motor and sensory function, and to promote myelination in peripheral nerve regeneration. In particular, the 15% MeCbl‐loaded PLCL conduit exhibits the most satisfactory recovery of sciatic nerves in rats with the largest diameter and thickest myelinated fibers.     

Anatomy and cell biology of the laryngeal motor neurons: Implications for the treatment of spasmodic dysphonia

Changes in neuroanatomical pathways in the central nervous system presumably play key roles in the pathogenetic mechanism underlying spasmodic dysphonia. However, practical considerations of accessibility to clinical intervention have focused efforts on treatments based on manipulations of laryngeal motor neurons, the most peripheral extent of these pathways. This review discusses aspects of the anatomy and cell biology of the laryngeal motor neurons, which provide a basis for the understanding of current techniques for the treatment of this disorder. In addition, consideration is given to the significance of unusual morphological characteristics of the laryngeal motor neurons and to cellular processes, which may ultimately offer potential for more selective clinical strategies.     

Elastically coupled molecular motors

We study the influence of filament elasticity on the motion of collective molecular motors. It is found that for a backbone flexibility exceeding a characteristic value (motor stiffness divided through the mean displacement between attached motors), the ability of motors to produce force reduces as compared to rigidly coupled motors, while the maximum velocity remains unchanged. The force-velocity-relation in two different analytic approximations is calculated and compared with Monte-Carlo simulations. Finally, we extend our model by introducing motors with a strain-dependent detachment rate. A remarkable crossover from the nearly hyperbolic shape of the Hill curve for stiff backbones to a linear force-velocity relation for very elastic backbones is found. With realistic model parameters we show that the backbone flexibility plays no role under physiological conditions in muscles, but it should be observable in certain in vitro assays. Received: 27 November 1997 / Revised: 20 February 1998 / Accepted: 27 March 1998