Regulatory mechanism of osteoclast activation

Osteoclasts are multinucleated, terminally differentiated cells which play an essential role in bone resorption. Osteoclasts exhibit high expression of the alpha(v)beta3 integrin, which binds to a variety of extracellular matrix proteins, including vitronectin, osteopontin and bone sialoprotein. RGD (Aug-Gly-Asp)-containing peptides, RGD-mimetics and blocking antibodies to alpha(v)beta3 integrin were shown to inhibit bone resorption in vitro and in vivo, suggesting that this integrin plays an important role in regulating osteoclast function. A number of signalling molecules were found to be involved in the alpha(v)beta3 integrin-dependent signalling pathway, including c-Src, Pyk2 and p130Cas. Both Pyk2 and p130Cas localize to the sealing zone of actively resorbing osteoclasts, suggesting their role in linking the adhesion of osteoclasts to the bone matrix, to cytoskeletal organization, and to the polarization and activation of these cells for bone resorption. In this article, we review the regulatory mechanism of osteoclast activation.     

The three-dimensional structure of the clear zone of a cultured osteoclast

Osteoclasts collected from long bones of newborn mice were cultured on dentine slices. Then, osteoclasts were sectioned by alternating semithin and ultrathin sections, and the three-dimensional reconstruction was made by the serial semithin sections. By this method, the present study showed first the three-dimensional structure of an osteoclast, especially the clear zone. A reconstructed osteoclast with complicated contours shifted from the lacuna, and its clear zone was a ring-shaped structure. By TEM, a new small lacuna was formed under the ruffled border, and the clear zone could be further classified into three types. The present study suggested that the synthetic observations of both three-dimensional structure and ultrastructure by transmission electron microscopy were necessary to determine whether the osteoclast was resorbing or migrating. According to these observations, the reconstructed osteoclast seemed to be migrating.     

Effects of osteoprotegerin administration on osteoclast differentiation and trabecular bone structure in osteoprotegerin-deficient mice

Osteoprotegerin (OPG)-deficient mice exhibit severe bone loss including the destruction of growth plate cartilage. Using OPG-deficient mice, we attempted to clarify the differentiation and ultrastructure of osteoclasts located on the destroyed growth plate cartilage and trabecular bone matrix in long bones. In (-/-) homozygous OPG knockout mice, adjacent to the growth plate cartilage, the formation of bone trabeculae without a calcified cartilaginous core resulted in an irregular chondrocyte distribution in the growth plate cartilage. At the metaphyseal ossification center, TRAP-positive osteoclasts showed unusual localization on both type-II collagen-positive cartilage and type-I collagen-positive bone matrix. Osteoclasts located on cartilage matrix lacked a typical ruffled border structure, but formed resorption lacunae. During growth plate cartilage destruction, osteoclasts formed ruffled border structures on bone matrix deposited on the remaining cartilage surfaces. These findings suggest that, in OPG (-/-) mice, osteoclast structure differs, depending on the matrix of either cartilage or bone. Then, we examined the effects of OPG administration on the internal trabecular bone structure and osteoclast differentiation in OPG (-/-) mice. OPG administration to OPG (-/-) mice significantly inhibited trabecular bone loss and maintained the internal trabecular bone structure, but did not reduce the osteoclast number on bone trabeculae. For most osteoclasts, OPG administration caused disappearance or reduction of the ruffled border, but induced neither necrotic nor apoptotic damages. These results suggest that OPG administration is an effective means of maintaining the internal structure and volume of trabecular bone in metabolic bone diseases by inhibition of osteoclastic bone resorption.     

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.     

Ultrastructural study of the effects of cytochalasin D administration on the structure and acid trimetaphosphatase activity of osteoclast.

To determine the role of the cytoskeleton consisting of the microfilaments in osteoclasts, cytochalasin D (CD) conjugated with PBS was administered intravenously to rats at a dose of 1 mg/100 g b.w. Control rats were given only PBS. Then the osteoclasts in the metaphyses of the humeri were examined ultrastructurally, as well as acid trimetaphosphatase (TMPase) cytochemistry. The plasma calcium (Ca) concentrations before and after CD and calcitonin administration were also measured. CD administration first caused a prominent reduction of ruffled borders and spreading of clear zones associated with the occurrence of large pale vacuoles in adjacent cytoplasm. At 1 hr after CD administration, the osteoclasts mostly lacked both ruffled borders and clear zones, but still maintained a normal intracellular organization of cytoplasmic organelles. Morphometric analysis confirmed that CD administration resulted in about 70% reduction of both ruffled border and clear zone areas. TMPase secretion from osteoclasts towards the resorbing bone surfaces was strongly inhibited by CD administration. At 1 hr after administration, although CD caused a decrease of plasma Ca concentrations in 4 of 7 examined rats similar to that caused by calcitonin treatment, there was a slight increase of plasma Ca concentrations in the other 3 rats. These results suggest that the structure and bone-resorbing function of the ruffled border-clear zone complex of the osteoclast is highly regulated by cytoskeleton consisting of microfilaments containing F-actin.     

CPLD在感温火灾探测系统中的应用

介绍了光纤光栅感温火灾探测系统的应用原理,并重点阐述了用CPLD设计虚拟MC14499器件模块,给出并解释了用VerilogHDL语言实现的部分程序和仿真测试结果。     

通信领域以说明书为依据的判定

当判断权利要求是否得到了说明书的支持时,需要根据说明书公开的内容,站在所属领域技术人员水平,来看待权利要求的上位概括或并列概括所涵盖的一个或多个下位或并列选择方式所对应的方案是否能够解决发明或实用新型所要解决的技术问题.     

3G中移动台主呼接入过程中安全问题分析

本文对当前3G反向链路呼叫及通话过程中的安全问题做了分析,并分别从MS和BS相互之间的AKA、信令完整性保护和数据保密、入侵检测等进行了讨论。另外,在讨论中适当地将安全与移动性管理相结合,并根据实际应用中的安全问题提出了一些新的设想和解决的方法。     

LCD器件电光参数测量中视差的研究

本文从理论和实验两方面研究了在ＬＣＤ器件电光参数测量中存在的视差随测量倾角的变化规律，视差对测量结果和测量仪器的影响及消除视差的方法。     

智慧交通在构建智慧城市中的重要作用

随着信息技术的不断发展,城市信息化应用水平不断提升,智慧城市建设应运而生。智慧城市的建设可以实现城市的可持续发展并且引领信息技术应用,对提升城市综合竞争力也具有重要意义。其中,智慧交通已被认为是解决城市交通拥堵,进而建设综合交通运输体系,实现交通运输基础设施智能化和促进交通运输业可持续发展的重要途径。文章指出,在现代社会,科技的发展是产业发展的重要基础,随着我国城市化进程的加快,交通问题却尤为突出,因此,发展智慧交通在构建智慧城市中具有重要作用。在当代社会,需要把智慧交通作为构建智慧城市的首要任务。     

Changes in the efferent impulsation in the vagus nerves during the metastasis of Lewis lung carcinoma in mice

In electrophysiological experiments the reflectory reaction of the efferent impulsation in the vagus nerve elicited by the stimulation of the lung and airway receptors was studied in the mice with the lung Lewis carcinoma. It has been established that the extension of the metastatic process was accompanied by the disturbances in the relationships of the central cholin- and dopaminergic mechanisms of the respiratory nervous regulation with hyperactivation of the former and depression of the latter. The use of the neurotropic drugs of the central action normalizing or disturbing these interrelations inhibits or stimulates, respectively, the metastatic process.     

智能变电站二次设备改造过程层网变动研究

本文结合湖北省柏泉500千伏智能变电站合并单元改造工程,分析改造工程中过程层网的交换机配置变化情况,研究相应保护工作通道及数据交换情况,并提出智能变电站二次回路改造中过程层网需要注意的内容.     

"通信原理"课程教学改革探索

针对我院省重点专业“电子信息工程”的必修主干专业基础课程。“通信原理”教学中存在的不利于培养和提高学生分析问题、解决问题的能力的因素，从课程的教学内容、教学手段等方面论述了课程改革的基本构想，并对课程的实践环节——设计性实验的改革进行了探讨。     

以"三个更新"推动非电理工类电工电子技术课程的教学改革

讨论了非电理工类电工电子技术课程的教学改革。提出一种新的教学理念以及新的教材编写观念,据此编写出版了《新编电工电子技术》,提倡将新的教学手段和教学方法用于教学过程诸环节,并进行了试点,取得良好的效果。     

回顾过去成绩斐然展望未来责任重大奚国华鼓励无线电管理工作者不断奋斗

1月11日-12日，2006年全国无线电管理工作会议在长沙举行。会议回顾了2005年无线电管理工作情况，部署了2006年无线电管理工作任务。在大会开幕式上，信息产业部副部长奚国华长达一个半小时热情洋溢的讲活，鼓舞了全国无线电管理工作者的士气。     

浅谈高校机房建设与管理

针对学校计算机机房建设与管理、提高计算机实验课的效果、发挥计算机机房在教学中的作用加以论述 ,描述了本校机房适应不同教学需要的三种联网方式 ,总结了网络化管理的优势 ,并阐述了多媒体技术在提高计算机实验教学效果的重要作用     

看美国未来如何在网上作战

互联网是当前最富有潜力的信息通信技术,它给人类生活的各个方面带来了显著的影响。然而,在造福人类的同时,互联网也给人类带来了沉重的灾难,特别是网络运用于军事领域,这一特征尤为明显,信息窃密与反窃密、入侵与反入侵、渗透与反渗透的斗争将以全新方式,在更广泛的空间和领域里展开。可以断言,21世纪是网络世纪,21世纪的文明是网络文明,计算机网络主宰着军事、经济乃至社会生活的全部。在这一背景下,网络战就上升到战争范畴,具有了战略意义。     

AML微波系统在海岛地区有线电视联网中的应用

介绍AML微波系统在海岛地区有线电视联网中的应用,阐述AML微波系统工作原理、微波收发点的选址、微波天线的固定安装、系统设计,同时探讨了施工过程中应注意的问题。     

以太网中双上行组网的弹性链路的设计与实现

为了在双上行组网的网络拓扑中避免形成环路,并进行冗余备份和快速倒换,传统方法是使用STP。但现有的STP的收敛速度慢,丢失流量较多,倒换时间较长,且协议复杂,会占用以太网交换机的大量资源。针对这些问题,提出了一种在双上行组网中实现主备链路冗余备份和快速倒换的弹性链路(RLink,Resilient Link)解决方案。对该方案的测试表明,能够实现预期的功能,并且占用资源少,易于操作。     

Considering the user in the wireless world

The near future promises significant advances in communication capabilities, but one of the keys to success is the capability understanding of the people with regards to its value and usage. In considering the role of the user in the wireless world of the future, the Human Perspective Working Group (WG1) of the Wireless World Research Forum has gathered input and developed positions in four important areas: methods, processes, and best practices for user-centered research and design; reference frameworks for modeling user needs within the context of wireless systems; user scenario creation and analysis; and user interaction technologies. This article provides an overview of WG1's work in these areas that are critical to ensuring that the future wireless world meets and exceeds the expectations of people in the coming decades.