Permeation study of the potassium channel from streptomyces Lividans

A three-state hopping model is established according to experiments to study permeation of an open-state potassium channel from Streptomyces Lividans (KcsA potassium channel). The master equations are used to characterize the dynamics of the system. In this model, ion conduction involves transitions of three states, with one three-ion state and two two-ion states in the selectivity filter respectively. In equilibrium, the well-known Nernst equation is deduced. It is further shown that the current follows Michaelis-Menten kinetics in steady state. According to the parameters provided by Nelson, the current-voltage relationship is proved to be ohmic and the current-concentration relationship is also obtained reasonably. Additional validation of the model in the characteristic time to reach the steady state for the potassium channel is also discussed. This model lays a possible physical basis for the permeation of ion channel, and opens an avenue for further research.     

Regulation of BMP4 on the proliferation and differentiation in SVZa neural stem cells

The neural stem cells in the anterior subventricular zone (SVZa) mainly generate the progenitors that will differentiate into neurons, and along a highly circumscribed migratory access Rostral migratory stream (RMS), they migrate to the olfactory bulbs (OB). To understand the effects of BMPs on SVZa neural stem cells, in this study BMP4 at various concentrations was used to induce SVZa neural stem cells, and the living cell labeling using BMP4 promotor conjugated with red fluorescence protein showed the expression of BMP4 dynamically. The results demonstrated that low BMP4 doses (1-5 ng/mL) promoted while high doses (10-100 ng/mL) inhibited the proliferation of SVZa neural stem cells, and BMP4 promotedneuron differentiation in the early stage (1-3 d), howeverm, it inhibited the neuron commitment after 4 d. Noggin, the antagonist of BMP4, blocked the physiological effects of BMP4. In OB, BMP4 is mainly to accelerate the progenitors to withdraw from the cell cycle and trigger the differentiation, and in RMS, it promotes the proliferation of committed progenitors and not differentiation, further in SVZa, BMP4 enhances astrocyte commitment.     

"黄光检骨"考

史料表明,世界上最早采用红油雨伞滤光方法检验尸体伤痕的明确记载,是在我国的北宋初期。南宋时期的提刑官宋慈则把此法用于检验尸骨伤痕。用黄油雨伞滤光、检验尸骨伤痕始于何时、何人?文献〔1〕中认为,此法亦始于宋慈。文章通过对现有史料的分析,得到了与其完全不同的结论。     

黑骨藤伸筋透骨喷雾剂中薄荷醇的测定

建立了气相色谱法测定黑骨藤伸筋透骨喷雾剂中薄荷脑含量。使用HP5890A气相色谱仪:FID氢火焰检测器,HP3396A色谱工作站,DB WAX(PEG 20M)15 m×0.53 mm×0.25μm弹性石英毛细管色谱柱;载气:高纯氮,载气流速为12 ml/min;进样口160℃,柱温:90℃(3 min,10℃/min)-120℃(3 min,20℃/min)-140℃(2 min);检测器温度200℃.薄荷脑标准曲线为Y=1.029X-0.0044;本法RSD均<1.5%;相当于样品中薄荷脑含量50%、100%、200%宽范围内的平均加标回收率分别为103.4%,98.82%,99.34%。本方法快速简便准确,可以用于黑骨藤伸筋透骨喷雾剂中薄荷脑含量的测定和产品质量控制。     

基于AR模型的松质骨BUA参数测量的研究

定量超声(quantitative ultrasonic,QUS)技术是一种间接测量骨矿密度(bone mineraldensity,BMD)的方法,它利用骨骼的宽带超声衰减(broadband ultrasound attenuation,BUA)等参数反映BMD.为了减少噪声的影响,提出将AR模型用于骨骼的BUA测量,通过仿真和样品实测结果发现,该方法与传统方法相比不仅可以得到较平稳的衰减曲线,还可以有效地提高测量精度.另外在实验中采用宽带超声传感器测量BUA,发现BUA在0.5~2.4 MHz区域内与频率仍具有较好的线性,从而将BUA的测量带宽扩展到1.9 MHz.     

植物蛋白激酶MAPK及其在病原信号传导中的作用

植物蛋白激酶在信号传递过程中越来越受到关注。促细胞分裂剂激活性蛋白激酶(MAPK)是一类存在于各种真核生物体中的丝氨酸/苏氨酸型蛋白激酶。它被上游激活因子MAPKK磷酸化而激活,并通过将底物蛋白上的丝氨酸和苏氨酸残基磷酸化而传递信号。它与其他一些信号分子组成MAPK级联信号通路,接受外界刺激信号,将信号转入细胞内,影响特定基因的表达,它的作用受到不同因子的调节。文章主要介绍了植物体中的MAPK的结构特点、分类以及其在病原信号传导中的作用。     

rhIGF-I对大鼠骨质疏松性骨折愈合过程中OPG表达的影响

目的：观察骨质疏松性骨折愈合不同阶段骨保护素（osteoprotegerin，OPG）的表达，探讨胰岛素生长因子-Ⅰ（recombinant human insulin-like growth factor，rhIGF-1）对该过程OPG表达的影响。方法：6月龄雌性大鼠40只，制备右股骨骨质疏松性骨折模型后，随机分为IGF治疗组及生理盐水对照组，并分别于术后第10、20、30、40d取骨痂，通过RT-PCR及ELISA检测各组骨痂OPG表达。结果：在大鼠骨质疏松性骨折愈合过程中成骨细胞活性降低，OPG表达呈弱阳性表达，骨折愈合缓慢；rhIGF-1局部注射治疗能增加骨痂中OPG的表达量（P〈0．05），促进骨质疏松性骨折愈合。结论：OPG是rhIGF-促骨质疏松性骨折愈合的重要下调因子。     

日本科学家利用患者自身细胞实现软骨再生

<正>日本科学家近日开发出一种利用患者自身细胞实现膝盖软骨再生的新疗法,可以用来治疗因交通事故和体育运动而造成的软骨损伤。来自神户大学的研究人员介绍说,他们从一名膝盖软骨损伤的青年女性膝盖处采集了微量软骨组织,然后将其所含的软骨细胞在果冻一样的凝胶中培养增殖,培养约2周后,再将软骨细胞连同凝胶移植回这名女性的膝盖处,受损软骨即可获得再生。软骨出现损伤时,以往的做法通常是切下其他部位的软骨来修补或是从骨髓中抽取干细胞来治疗,但这些治疗方法仅限于4平方厘米以内的创伤,而新疗法将治疗范围扩大到了9平方厘米,同时还可     

骨盆内移截骨加植骨造盖治疗大龄儿童先天性髋关节脱位

目的：研究一种大龄儿童先天性髋关节脱位的新术式,为解决大龄儿童先天性髋关节脱位、头臼不称、即股骨头大、髋臼小,用其他术式无法覆盖包容股骨头的问题.方法：骨盆内移截骨加植骨造盖及粗隆下短缩旋转截骨术治疗头臼不称的大龄儿童先天性髋关节脱位.结果：本组15例,据周永德评定标准,除有2例髋关节屈曲活动受限、1例轻度股骨头坏死外,其余均为优良,无一例半脱位及全脱位.结论：大龄先天性髋关节脱位的头臼不称、头大臼小、真假臼相连者可以推广应用骨盆内移加植骨造盖术,其优点在于单纯骨盆内移术所不能解决的真臼边缘与近端不能很好衔接的问题.     

骨制品的矿质元素及食用价值

骨制品含有钙、磷、铁、锌等多种矿质元素，具有人体需要的矿质元素的重要来源，应尽快开发和充分利用。