Biocompatibility studies of silk fibroin-based artificial nerve grafts in vitro and in vivo

Silk fibroin (SF) has been used extensively in the biomedical field including tissue engineering for the generation of artificial bones, skins or ligaments. We have previously reported on good in vitro biocompatibility of SF fibers with peripheral nerve tissues and cells. In the present study, we developed a novel design of the SF-based artificial nerve graft (SF graft) which was composed of a SF-nerve guidance conduit (NGC) inserted with SF fibers. MTT assay was performed to determine the cytotoxicity of the SF-NGC extract fluid on the cultured L929 cells derived from an immortalized mouse fibroblast cell line. In addition, this SF graft was implanted into adult rats for bridging a 10-mm long sciatic nerve defect. The following-up experiments at initial stage (1—4 week) of nerve regeneration including routine blood tests and histochemical investigation were conducted to evaluate the in vivo biocompatibility of the SF graft with peripheral nerves. The results demonstrated that the SF-NGC graft was biocompatible with the surrounding tissues and cells due to its low inflammatory potential with a grade 0 under the U.S. Pharmacopeia guidelines and it was generally suitable to a certain degree for bridging peripheral nerve defects in virtue of supporting Schwann cell adherence, expansion and migration. Therefore the SF graft is a promising alternative to classical autografts for peripheral nerve repair.     

论穆旦诗歌对现世的关怀与对生命的思考

穆旦作为诗人在中国新诗史上长期得不到应有的重视,一方面是由于动荡和异化的时代有意或无意地忽略甚至剥夺诗人说话的权利,另一方面是因为他对现世社会和人性中弊病的追问和揭露致使他缺席于时代合唱之潮流。他对民众苦难的关注,对文明社会的虚伪的嘲讽,对内部精神世界的审视,以及对生命存在意义的形而上的思索,无不显示了他对现世的强劲的介入精神和可贵的担当意识。     

疼痛的意识与意识中的疼痛

 疼痛是长期困扰人类的临床、心理与社会问题。近年来,随着疼痛的神经机制研究的进展,相关研究日益指向疼痛相关的心理学过程。疼痛或对伤害的感受可能较早就出现在进化过程中,并且很久以前就具备了心理和社会属性。大脑从海量的神经冲动中,把伤害性信息以痛觉的方式呈现给意识,并伴随着情绪信息以反映其可能的伤害程度。意识还用类似的方式呈现和处理社会关系方面的伤害。由于生活经历的不同,每个人对痛觉的认知也可能有极大的差异。从心理学和神经科学的角度进一步了解疼痛,可能可以为了解疼痛本质提供依据。     

基于SVM的新生儿疼痛表情识别

近十年来新生儿疼痛引起医护人员的广泛关注.由于新生儿不能自述疼痛的感受,疼痛评估成为新生儿科学中最具挑战性的一个难题.新生儿"疼痛面容"(蹙眉、挤眼、鼻唇沟加深、张口)被认为是最可靠的疼痛指标,且持续时间最长,因而被国际上常用的新生儿疼痛评估工具作为评估指标.然而,这些疼痛评估工具往往受到临床医护人员主观因素的影响.文中旨在解决上述问题,提出利用支持向量机(SVM)技术对新生儿疼痛与非疼痛面部表情进行分类识别.对210幅照片的表情图像进行了研究,比较了线性核函数SVM、多项式核函数SVM(d=2,3,4)以及径向基函数SVM等5种不同分类器的性能.实验结果表明,阶数d=3的多项式核函数SVM分类器的性能最佳,对疼痛和非疼痛表情分类的识别率达到93.33%,对疼痛与安静表情的分类识别率为94.17%,对疼痛与哭表情的分类识别率为83.13%,初步具备了在新生儿疼痛评估中的潜在应用价值.     

Structural and functional annotation of PR/SET Domain (PRDM) protein family: In-silico study elaborating role of PRDM12 mutation in congenital insensitivity to pain

Congenital insensitivity to pain (CIP), classified as a type of hereditary sensory and autonomic neuropathies, is a rare disease in which the affected individuals fail to perceive sensation of pain. One of the PR/SET Domain Proteins, PRDM12, has been identified in recent past as a candidate gene for congenital insensitivity to pain. In the present study, we performed whole exome sequencing in a Pakistani family with CIP phenotype to ascertain the causative mutation. We identified a previously described alanine repeat duplication in PRDM12 (Ala353_Ala359dup) in this family. After this, we performed structural annotations for PR/SET Domain (PRDM) containing protein family to prognosticate the potential hypothetical structure of PRDM proteins with physical and chemical parameters. Out of nineteen members of this family, four members (PRDM5, PRDM8, PRDM12 and PRDM13) were specially focused because of their role in neurological disorders. Predictions about structure and interactions of these proteins revealed novel interacting molecules and pathways. Detailed in silico analysis of PRDM12 was performed to elaborate importance of its domain structure in interaction with other proteins and its role in pain insensitivity phenotype. These results have substantially enhanced our understanding regarding the etiology of congenital pain insensitivity and would stimulate further research on therapy and prevention.     

A new coumarin from Murraya alata activates TRPV1 channel

Abstract

One new coumarin, muralatin R, was isolated from the leaves of Murraya alata Drake (Rutaceae). Its structure was elucidated by extensive analysis of the NMR and MS data, along with the specific rotation comparison. Muralatin R was found to be capable of activating the transient receptor potential vanilloid 1 (TRPV1) channel through desensitization mechanism. The results supply reference for clarification of the therapeutic basis and mechanism of action of Murraya plants for treating psychogenic pain or somatoform pain disorders.     

Increased numbers of oligodendrocyte lineage cells in the optic nerves of cerebroside sulfotransferase knockout mice

Sulfatide is a myelin glycolipid that functions in the formation of paranodal axo-glial junctions in vivo and in the regulation of oligodendrocyte differentiation in vitro. Cerebroside sulfotransferase (CST) catalyzes the production of two sulfated glycolipids, sulfatide and proligodendroblast antigen, in oligodendrocyte lineage cells. Recent studies have demonstrated significant increases in oligodendrocytes from the myelination stage through adulthood in brain and spinal cord under CST-deficient conditions. However, whether these result from excess migration or in situ proliferation during development is undetermined. In the present study, CST-deficient optic nerves were used to examine migration and proliferation of oligodendrocyte precursor cells (OPCs) under sulfated glycolipid-deficient conditions. In adults, more NG2-positive OPCs and fully differentiated cells were observed. In developing optic nerves, the number of cells at the leading edge of migration was similar in CST-deficient and wild-type mice. However, BrdU(+) proliferating OPCs were more abundant in CST-deficient mice. These results suggest that sulfated glycolipids may be involved in proliferation of OPCs in vivo.     

Surface-Mediated Synthesis of O-Alkyl 2-Methoxyethyl Alkylphosphonates Under Solvent Free Conditions: Potential Marker of Nerve Agents

This article describes rapid and efficient surface mediated synthesis of O-alkyl 2-methoxyethyl alkylphosphonates from alkylphosphonic acids and alcohols using dicyclohexyl carbodiimide (DCC)-Celite as a solid support. These compounds are markers of nerve agents. 2-Methoxyethyl methylphosphonic acids (2a–d) were reacted with various alcohols to yield O-alkyl 2-methoxyethyl alkylphosphonates (AMEAPs, 3a–m). This synthetic method has advantages over other methods in terms of selectivity, shorter reaction time, high yield, and easy work-up.     

Structural determination of nerve agent markers using gas chromatography mass spectrometry after derivatization with 3‐pyridyldiazomethane

Nerve agents are a class of organophosphorous chemicals that are prohibited under the Chemical Weapons Convention. Their degradation products, phosphonic acids, are analyzed as markers of nerve agent contamination and use. Because the phosphonic acids are non‐volatile and very polar, their identification by GC‐MS requires a derivatization step prior to analysis. Standard derivatization methods for gas‐chromatography electron‐impact mass‐spectrometry analysis give very similar spectra for many alkyl phosphonic acid isomers, which complicates the identification process. We present a new reagent, 3‐pyridyldiazomethane, for preparing picolinyl ester derivatives of alkyl methylphosphonic acids facilitating the determination of their structure by enhancing predictable fragmentation of the O‐alkyl chain. This fragmentation is directed by the nitrogen nucleus of the pyridyl moiety that abstracts hydrogen from the O‐alkyl chain, inducing radical cleavage of the carbon–carbon bonds and thereby causing extensive fragmentation that can be used for detailed structure elucidation of the O‐alkyl moiety. The separability of related isomers was tested by comparing the spectra of the picolinyl esters formed from twelve hexyl methylphosphonic acid isomers. Spectral library matches and principal component analysis showed that the picolinyl esters were more effectively separated than the corresponding trimethylsilyl derivatives used in the standard operating procedures. The suggested method will improve the unambiguous structural determination process for phosphonic acids. Copyright © 2013 John Wiley & Sons, Ltd.     

铜代谢紊乱对脑神经系统疾病的影响

铜是维持哺乳动物正常生理活动的微量元素,体内铜的含量与细胞呼吸、自由基防御、血管生成、神经细胞和机体的生长发育有密切关系,它还参与脑生理活动的调节.体内铜的含量、转运及分布都受到精密的调控,铜元素缺乏和过量时都严重影响机体健康.铜及铜相关酶生物系统中对生命过程有着重要的作用,其代谢异常往往会导致严重的神经症状和神经系统疾病.本文将综述铜代谢紊乱对脑神经系统疾病的影响.