体外培养兔骨髓间充质干细胞的超微结构观察

本文对体外培养的新西兰大白兔骨髓间充质干细胞 (ＭＳＣｓ)的超微结构进行了电镜观察 ,为选择良好的细胞生长状态 ,应用于组织工程提供实验依据。分别对原代和传代后第二、三、四、五代细胞进行了透射电镜观察。结果原代及第二、三代细胞胞核呈圆或卵圆不规则形 ,双层核膜完整 ,核仁大而明显 ,部分细胞见有 2～ 3个核仁 ,常异染色质分布均匀。胞浆丰富 ,呈中等电子密度 ;细胞器较简单 ,但数量丰富 ,结构清晰 ,如粗面内质网、滑面内质网、线粒体等 (图 1)。第四、五代细胞透射电镜下见有部分细胞开始出现结构异常现象。有些细胞的细胞核内异…     

重组RANK蛋白抑制破骨细胞活性的实验研究

目的研究重组RANK蛋白在体外实验中对破骨细胞的抑制作用。方法成骨细胞与RAW264.7细胞以4∶1比例混合培养6d,以抗酒石酸酸性磷酸酶(TRAP)染色鉴定后,加入3种浓度(10-4g/L、10-5g/L、10-6g/L)重组RANK蛋白,并设空白对照。3d后观察破骨细胞数目和形态,计数骨磨片吸收陷窝。结果混合培养6d后,体系中可见成熟破骨细胞出现。加重组RANK蛋白3d后,与对照组相比,各药物组TRAP阳性细胞个数、骨磨片吸收陷窝计数均明显减少。结论体外实验中重组RANK蛋白可以显著抑制破骨细胞活性及吸收功能。     

Clathrin sheets on the protoplasmic surface of ventral membranes of osteoclasts in culture

Physical cell-shearing resulted in various degrees of disruption of the basolateral (upper) membranes, cytoskeletons or cell organelles and exposed the protoplasmic surface of ventral (adhesion) membranes of osteoclasts that were attached to the underlying substratum, such as coverslips, mica or synthetic apatite plates. Freeze-dried replicas of the ventral membranes left behind on the substratum after cell-shearing provided three-dimensional information on the ultrastructure of the protoplasmic membrane surface of cultured osteoclasts. An extensive area of the protoplasmic surface and various amounts of cytoskeletal structures attached to the adherent ventral surface of the plasma membrane were visible. In particular, the most characteristic finding of the present study is that numerous clathrin sheets displaying various sizes, shapes and curvature were revealed on the ventral membrane. The polygon substructures of the clathrin lattices appeared to be composed of hexagons with a few pentagons interspersed. They were seen at the peripheral membranes where they were situated at the sites of close contact with the underlying substratum. In addition, clathrin lattices were never observed on the basolateral (upper) membranes. In favourable stereo views, most cytoskeletons were not in direct contact with the clathrin sheets. However, a few observations indicated possible remnants of cytoskeletons attached to clathrin lattices. Podosomes did not have a direct structural relationship to clathrin lattices. Although it is generally accepted that cytoskeletal podosomes in motile cells, such as osteoclasts, play a major role in cell adhesion, the present study indicates that membrane-associated clathrin might also function during attachment to the substrate. In this regard, clathrin is thought to be required for receptor-mediated endocytosis, but whether it might also function in cell attachment is still a matter for debate. This type of clathrin-related adhesion appears to be a previously unrecognized site of cell/substrate adhesion in osteoclasts. To assess this possible function, we focused on clathrin and related cytoskeletal elements on the ventral membranes of cultured osteoclasts.     

WCDMA差异化服务探讨

通过对WCDMA网络中各种业务特性和用户需求的分析,指出了如何在WCDMA中采用QoS机制降低运营成本并提高终端用户的满意度,给出了差异化QoS的实现方案。     

电子元器件质量等级辨析

分析了电子元器件质量保证等级和可靠性预计质量等级,对其概念、规范、标识等内容进行辨析,并对易混淆的部分举例进行说明,为产品研制中规范使用质量等级应用和管理元器件提供帮助。     

Thiamine pyrophosphatase activity in the Golgi apparatus of calcitonin-treated osteoclasts.

The thiamine pyrophosphatase (TPPase) activity described by Novikoff and Goldfisher was examined in osteoclasts affected by calcitonin in order to elucidate whether the morphological and functional changes of the osteoclasts have an influence over the secretion function of their Golgi apparatus. The Golgi apparatus of osteoclasts of which the ruffled border had disappeared and bone resorption discontinued as the result of treatment with calcitonin showed a slight TPPase activity. The reaction products of the enzyme in these inactive osteoclasts were distinctly fewer than that of control osteoclasts, which were not affected by calcitonin. From these results, it is suggested that there may be a connection between the morphological and functional changes of osteoclasts and the secretion function of the Golgi apparatus.     

Osteoprotegerin administration reduces femural bone loss in ovariectomized mice via impairment of osteoclast structure and function

Osteoprotegerin (OPG) is a novel osteoblast-derived secreted member of the tumour necrosis factor receptor superfamily that inhibits osteoclastogenesis. We examined the effects of OPG administration on the distribution, ultrastructure and vacuolar-type H+-ATPase expression of osteoclasts and resulting trabecular bone loss in the femurs of ovariectomized (OVX) mice. Two-month-old female ddY mice were allocated to the following groups: (1) pretreatment base-line controls; (2) untreated sham-operated controls; (3) untreated OVX; and (4) OPG-administered OVX mice. Postoperatively, OPG (0.3 mg kg(-1) day(-1)) was intraperitoneally administered daily to OVX mice for 7 days. On postoperative day 7, all mice were sacrificed, and the dissected femurs were examined by means of light and immunoelectron microscopy and quantitative backscattered-electron image analysis. Backscattered-electron examination revealed that trabecular bone area/unit medullary area in untreated OVX mice was significantly lower than that of base-line control and sham-operated control mice. Compared with untreated OVX mice, OPG administration to OVX mice significantly increased trabecular bone area, which was similar to that of sham-operated control mice. Surprisingly, the number of TRAP-positive osteoclasts along the trabecular bone surfaces in OPG-administered OVX mice was not significantly decreased compared with that of sham-operated control and untreated OVX mice. Ultrastructurally, OPG administration caused disappearance of ruffled borders in most osteoclasts, but induced neither necrotic nor apoptotic changes. In addition, the expression of vacuolar-type H+-ATPase in osteoclasts was decreased by OPG administration. Our results suggest that low-dose OPG administration significantly reduces trabecular bone loss in OVX mice via impairment of the structure and bone resorbing activity of osteoclasts.     

模拟与数字调制方式的非线性变换识别方法

在多级调制识别系统中,首先需要区分调制方式是模拟调制还是数字调制。本文提出一种非线性变换方法对截获信号序列进行预处理,然后通过提取该序列的差分序列方差作为唯一的分类特征,就可以在较低信躁比条件下有效区分模拟和数字调制方式。这种非线性变换方法简单直接,所用特征少,并易于软件实现,尤其适合软件无线电等实时性要求高的应用领域。     

A QRS Preprocessor Based on Digital Differentiation

Digital preprocessors can ease the increasing data collection demands placed on real-time computers in patient monitoring. This paper describes a preprocessor that detects in real time an electrocardiogram QRS complex and computes the R-R interval. Detection is performed using multiple digital differentiation, which is encouraging as an ultrareliable means for locating the QRS. Inherent in the technique is a dependable control that can automatically compensate for signal-level variations. Clinical data demonstrate that detection is insensitive to low- and high-frequency noise, from baseline drift to muscle artifact and cautery bursts. The device can be connected directly to a patient, whose safety is guaranteed by optoelectronic isolation and interelectrode current limiting. Preprocessor operation has been human-engineered to a simple on/off procedure.     

浮游植物荧光特征提取及识别测定技术

为了区分和识别不同门和属的浮游植物,以coiflet2小波函数(coif2)为基函数对4个门类9个属的12种浮游植物的三维荧光光谱进行分解,选取第三层尺度分量作为浮游植物识别特征谱.不同门类和属(种)的浮游植物的特征谱具有明显的特征差异.Bayes判别分析结果表明,此类特征谱对浮游植物在门类层次上的总分类正确率可达99.0%,属层次上的总分类正确率可达97.4%.以聚类分析法确立浮游植物特征谱的标准谱库,以此为基础,利用线性回归法(非负最小二乘法解析)建立浮游植物荧光识别测定技术.该技术对单种浮游植物样品在门类及属层次上的识别正确率均大于98.0%,当加入10%或20%的随机噪声时,在门类及属的层次上的识别正确率分别大于98.0%和85.0%;对浮游植物混合样品中的优势种在门及属的层次上的识别正确率均为100%.     

基于图像差异度的太阳像二值化算法研究

图像二值化是数字图像处理系统中基本而关键的技术,阈值分割是实现二值化的重要途径,假定图像的目标与背景是可以分离且存在一定差异的,则基于图像中目标和背景与原图像的差异,建立恰当的差异度公式。提出相应的算法,并对太阳像进行闽值分割。试验结果表明,与一些传统方法相比,该方法能很好地区分目标和背景,得到了较好的二值化处理效果。     

时段差异化网络参数动态配置研究

文章顺应后3G时代网络精细优化工作需求,进一步挖掘网络提质潜力,提出时段差异化创新优化方法。该方法充分利用网络时段差异特性和不同参数策略特性,从时间这个崭新维度引入不同时段网络参数动态配置的思想,改善整体网络质量和用户感知。目前该优化方法已在3G网络应用并获得良好效果,并预期在4G网络中可进一步往时空联动优化作深入研究。     

Screening Mesenchymal Stem Cell Attachment and Differentiation on Porous Silicon Gradients

The profound effects that nanoscale surface topography exerts on cell behavior are highly relevant to the development of advanced biomaterials and to advances in tissue engineering and regenerative medicine. Here, an asymmetric anodization procedure is used to produce n‐type porous silicon (pSi) gradients with pore sizes ranging from tens to hundreds of nanometers in diameter and changes in the ridge nanoroughness from a few to tens nanometers. Rat mesenchymal stem cells (rMSCs) adhere poorly at the regions with small pore size but high ridge roughness. Cell adhesion is increased gradually towards the large pore size but low ridge roughness end of the pSi gradients. Surface topography influences cell differentiation, but not cell proliferation. Osteogenesis of rMSCs is enhanced by porous topography with a ridge roughness lower than 10 nm, while adipogenesis of rMSCs is enhanced on the entire pSi gradient compared with flat Si substrates. The results demonstrate that the gradient format allows in‐depth screening of surface parameters that are important for the control of mammalian cell behavior, thereby advancing the development of new and improved biomaterials for orthopaedic and tissue engineering applications.     

Heating and structural alterations in cartilage under laserradiation

The authors have developed a theoretical model to calculate the temperature field and the spatial distribution of modified cartilage following laser irradiation. The model incorporates both thermal and mass transfer in a tissue with bulk absorption of laser radiation, water evaporation from the surfaces of a slab, and temperature dependence of the diffusion coefficient. The authors propose that water undergoes a bound-to-free phase transition in cartilage heated to about 70°C and the mobility of proteoglycan units in the cartilage matrix increases. Movement of the proteoglycan units takes place only when the temperature exceeds 70°C and results in tissue denaturation. Using their model, the authors show: (1) the maximal temperature is reached not on the surface irradiated but rather at some distance below; (2) surface temperature reaches its asymptotic value quicker than the maximal temperature; and (3) the depth of the denatured tissue volume strongly depends on laser fluency, wavelength, exposure time, and cartilage thickness. The model allows for the prediction and control of temperature and depth of structural alterations during the course of laser reshaping and treatment of cartilage     

微粒形体分布函数与影响因子函数的进一步研究

基于任意形体微粒的半椭圆模型及其理论，对其中的微粒形体分布函数和其影响因子进行了理论和实验研究。研究结果表明：1）微粒粒度分布在大粒度分布区对微粒形体影响因子的影响甚微，可以忽略其影响作用；2）对于微米量级的微粒，其衍射图象反映了微粒的形体，从而可用于微粒形体分布函数的定义。     

基于分数阶梯度驱动的主动Demons算法研究

图像非刚性配准在计算机视觉和医学图像有着重要的作用.Demons算法被证明是解决非刚性配准的有效方法,然而存在的Demons非刚性配准算法对灰度均匀和弱纹理区域的图像配准精度低,优化易陷入局部极小导致配准速度缓慢.针对该问题,将R-L（Riemann-Liouville）分数阶微分引入到主动Demons算法中,提出了基于R-L分数阶梯度驱动的主动Demons算法.本文将R-L分数阶梯度代替传统的梯度算子,不但可以增强图像的细节信息,而且可以增强灰度均匀和弱纹理区域的梯度信息,从而提高了图像配准精度和速度.另外,通过实验给出了配准精度与R-L分数阶模板参数之间的关系,从而为模板最佳参数的选取提供了依据.尽管不同类型的图像其最佳参数是不同的,但是其最佳配准阶次一般在0~1之间.理论分析和实验结果均表明,该算法可以用于灰度均匀和弱纹理区域的图像配准,且配准精度和速度都有明显的提高,本文方法是Demons算法应用的一个重要延伸.