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《中国科学基金》2019,(1)
造血干祖细胞可以通过增殖分化产生红细胞、白细胞、血小板等人体内所有类型的血液细胞,维持脊椎动物的终生造血。在发育过程中,造血干祖细胞诞生于动脉—性腺—中肾(AGM)区域后,后通过归巢锚定在特定的微环境中进行自我更新或向下游各血系分化。复杂的血管结构以及其他基质成份,如基质细胞等,构成了独特的造血微环境,调控造血过程的进行。然而,由于造血过程时空跨度非常大,观察手段十分有限,目前对造血微环境的精细结构以及调控造血干祖细胞归巢的分子细胞机制仍然知之甚少。为攻克这一难题,本团队在优化活体成像技术的基础上,进一步整合活体免疫荧光标记、遗传调控和图像重构计算等方法,对斑马鱼尾部造血组织(相当于哺乳动物胎肝)中的造血干祖细胞的归巢过程进行了解析,揭示了独特的微血管结构对造血干祖细胞停留的调控作用。在研究中,本团队还意外地发现了一种全新的微环境细胞,并将其命名为"先导细胞"。这类细胞是先前未被定义过的巨噬细胞新亚型,存在于归巢"热点区域"中,表现出"巡逻行为",可以识别进入造血组织的造血干细胞并将其引入特定的血管结构中,从而实现造血干细胞的归巢。此项研究为造血干细胞移植相关的转化研究开辟了新的方向。 相似文献
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本实验运用离子选择性微电极技术直接测定了鼠胆道梗阻前后肝、肾细胞内的胆汁酸活度。结果表明，胆道梗阻２周，肝、肾细胞内胆汁酸活度明显升高，其中肝细胞内达５．４６ｍｍｏｌ／Ｌ，肾细胞内达０．３７ｍｍｏｌ／Ｌ，已达到或接近体外膜损害浓度，提示胆汁酸可能是梗阻性黄疸引起肝、肾细胞超微结构损害的因素之一。 相似文献
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花中含有丰富的β—胡萝卜素(维生素A原)。β—胡萝卜素进入人体能被肠壁或肝脏加双氧酶降为两分子维生素A(视黄醇、视黄醛、视黄酸)。其中视黄酸有抗癌作用,主要是保证正常细胞(膜外侧寡糖链)的不断修复及更新,不让物理的、化学的、生物的致癌物质进入细胞而致癌。 β—胡萝卜素能消除机体产生的自由基。如自由基过多,能损伤细胞粒中的基因,造成基因突变,而基因突变是细胞癌变的分子基础。实验室内进行的动物实验,证实了β—胡萝卜素能消除幅照动物产生的自由基。 放疗和化疗是目前癌症治疗的重要手段,但副作用大,除周身毒性反应外,造血系统,尤其是白细胞大量损伤,致使白细胞下降。放疗、化疗药物缺乏特异性选择作用,它在杀伤肿瘤细胞的同时,也损伤了机体的正常组织,使得标本俱伤。 机体免疫反应能力降低,使肿瘤发生、发展和更加恶化,患肿瘤时,T淋巴细胞机能和数量均有所下降。施行放疗、化疗,机体的免疫功能有一定的抑制作用。玫瑰花形成试验证明:正常人周围淋巴细胞中形成玫瑰的细胞占69.4％,59例恶性肿瘤病人则占41.51％,而放疗后仅占34.17％,显然肿瘤病人放疗后玫瑰花形成的细胞值低于正常人。肿瘤病人的免疫机能原本就低于正常人,实施放疗后更有所降低。 相似文献
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1．菌类食物：如黑木耳、银耳、蘑菇、香菇等。这些菌类含有丰富的硒。经常服用可降血压、降胆固醇、防止血管硬化、提高机体免疫功能，增加体内免疫球蛋白的含量，兴奋骨髓造血功能及滑肠、洁血、解毒、增智等。 相似文献
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在前人工作的基础上综述了过量铝对植物、动物及人体的危害。过高铝会抑制植物的生长并影响植物体内正常的代谢过程和其它元素的吸收;体内过多的铝对人及动物的中枢神经系统、脑、肝、骨、肾、细胞、造血系统、人体免疫功能、胚胎以及学习和记忆等均有不良影响;铝可干扰孕妇体内的酸碱平衡,使卵巢萎缩,影响胎儿生长并影响机体磷、钙的代谢等。 相似文献
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干细胞技术
干细胞是机体内一类具有分化成为其他各种类型细胞的能力的一类多潜能细胞。干细胞具有自我更新和多潜能分化两种重要的能力。根据干细胞的来源不同,可以分为胚胎干细胞与成体干细胞。而根据干细胞分化潜能的不同,可以分为全能性干细胞与多能性干细胞。胚胎干细胞来源于早期胚胎发育的囊胚,囊胚内部细胞团经过机械分离、体外培养与扩增,具有自我更新与发育成为机体各个组织的能力。胚胎干细胞具有重要的医学与生物学价值,可以应用于临床治疗某些疾病。造血干细胞和神经干细胞等在临床治疗中已经发挥了重要的作用, 相似文献
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藏成药七十味珍珠丸中矿物质元素在体内蓄积性水平研究 总被引：1，自引：0，他引：1
名贵藏成药七十味珍珠丸是传统藏药的典型代表,疗效显著.其中矿物类药的大量运用为现代医学科学不可理喻,给传统藏医药学的健康发展带来了困惑。以金诃七十味珍珠丸为研究材料,以Wistar大白鼠为试验对象,用等离子体发射光谱(ICP AES)和氢化物原子吸收光谱(HAAS)等分析仪器,测定了对照组和给药组实验动物在连续 1 8周试验期间心、肝、肾等组织器官中的矿物质元素含量水平,阐述金诃七十味珍珠丸中矿物质元素在动物主要组织器官中的长期蓄积性及其对生物机体的毒性效应 相似文献
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王同江 《内蒙古科技与经济》2009,(13):88-89
文章论述了在金融危机中，我国西部发展关键在于自身的发展与提高，指出它不应是被动的受血者，而应是充满活力的具有自我造血功能的鲜活的有机体。 相似文献
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A research group led by Prof. ZHAI Qiwei from the Institute for Nutritional Sciences under the CAS Shanghai Institutes for Biological Sciences has discovered that even relatively low doses of resveratrol-a chemical found in the skins of red grapes in red wine-can improve the sensitivity of mice to the hormone insulin according to a report in the October issue of Cell Metabolism.…… 《中国科学院院刊(英文版)》2008,22(1):14-15
Aresearch group led by Prof. ZHAI Qiwei from the Institute for Nutritional Sciences under the CAS Shanghai Institutes for Biological Sciences has discovered that even relatively low doses of resveratrol--a chemical found in the skins of red grapes and in red wine--can improve the sensitivity of mice to the hormone insulin, according to a report in the October,2007 issue of Cell Metabolism. As insulin resistance is often characterized as the most critical factor contributing to the development of Type 2 diabetes, the findings“provide a potential new therapeutic approach for preventing or treating” both conditions, the researchers said. 相似文献
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Marjorie Armstrong-Stassen Margaret Landstrom Ramona Lumpkin 《The Information Society》1998,14(2):153-164
This study examined how students who had no prior experience with videoconferencing would react to the use of videoconferencing as an instructional medium. Students enrolled in seven different courses completed a questionnaire at the beginning of the semester and again at the end of the semester. Students at the origination and remote sites did not differ in their reactions toward videoconferencing but there was a significant difference for gender. Women reacted less favorably to videoconferencing. Compared to the beginning of the semester, students reported significantly less positive attitudes toward taking a course through videoconferencing at the end of the semester. There were no significant differences in students' attitudes toward videoconferencing across courses at the beginning of the semester but there were significant differences across the courses at the end of the semester. The results suggest the need for better preparation for both students and instructors. 相似文献
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A joint study by Prof. ZHANG Zhibin from the CAS Institute of Zoology his co-workers from Norway US Swiss have indicated that historical outbreaks of migratory locusts in China were associated with cold spells suggesting that China's projected climate warming could decrease the pest's numbers. The study was published in Proceedings of the National Academy of Sciences on September .…… 《中国科学院院刊(英文版)》2008,22(1):6-7
Ajoint study by Prof. ZHANG Zhibin from the CAS Institute of Zoology and his co-workers from Norway, US and Swiss have indicated that historical outbreaks of migratory locusts in China were associated with cold spells, suggesting that China＇s projected climate warming could decrease the pest＇s numbers. The study was published in Proceedings of theNational Academy of Sciences on 17 September, 2007. 相似文献
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Active biological molecules functional structures can be fabricated into a bio-mimetic system by using molecular assembly method. Such materials can be used for the drug delivery disease diagnosis therapy new nanodevice construction.…… 《中国科学院院刊(英文版)》2008,22(1):22-22
Active biological molecules and functional structures can be fabricated into a bio-mimetic system by using molecular assembly method. Such materials can be used for the drug delivery, disease diagnosis and therapy, and new nanodevice construction. 相似文献
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Caroline Haythornthwaite 《The Information Society》2001,17(3):211-226
A computer-mediated group is a complex entity whose members exchange many types of information via multiple means of communication in pursuit of goals specific to their environment. Over time, they coordinate technical features of media with locally enacted use to achieve a viable working arrangement. To explore this complex interaction, a case study is presented of the social networks of interactions and media use among members of a class of computer-supported distance learners. Results show how group structures associated with project teams dominated who communicated with whom, about what, and via which media over the term, and how media came to occupy their own communication niches: Webboard for diffuse class-wide communication; Internet Relay Chat more to named others but still for general communication across the class; and e-mail primarily for intrateam communication. Face-to-face interaction, occurring only during a short on-campus session, appears to have had a catalytic effect on social and emotional exchanges. Results suggest the need to structure exchanges to balance class-wide sharing of ideas with subgroup interactions that facilitate project completion, and to provide media that support these two modes of interaction. 相似文献
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《中国科学院院刊(英文版)》2008,22(1):2-3
CAS should stick to the principle of rendering service to, and giving impetus for, the development of China＇s science enterprise by making S＆T innovations, said CAS President LU Yongxiang. The CAS president made the remarks in a recent talk to communicate the gist of the winter session of the Party＇s Leading-member Group at CAS, which was held from 7 to 11 January in Beijing. 相似文献
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《中国科学院院刊(英文版)》2008,22(1)
With great care, Dr. ZHOU Zhonghe takes out a package wrapped by cotton tissue from a drawer and says: "This is the gem of our collections: the fossil of a bird that lived 125 million years ago!" Then, pointing at a tiny mound, he explains: "Look, this is the claw and that is the head. It was in the egg shell and ready to hatch ... The species fell into a family of waterside inhabitants." 相似文献
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Electronic data interchange (EDI) provides means for interorganizational communication, creates network externalities, requires an advanced information technology (IT) infrastructure, and relies on standards. In the diffusion of such innovations, institutional involvement is imperative. Such institutions contain governmental agencies, national and global standardization organizations, local government, and nonprofit private organizations like industry associations. The last type of organizations we call intermediating institutions. They intermediate or coordinate ("inscribe") the activities of a group of would-be adopters. Unfortunately, little is known of how these organizations shape the EDI diffusion trajectory. In this article we examine one specific type of intermediating organizations?industry associations?and how they advanced the EDI diffusion process in the grocery sectors of Hong Kong, Denmark and Finland. We identify six institutional measures, placed into a matrix formed by the mode of involvement (influence vs. regulation) and the type of diffusion force (supply push vs. demand pull), that can be mobilized to further the EDI diffusion. Industry associations were found to be active users of all these measures to varying degrees. Their role was critical especially in knowledge building, knowledge deployment, and standard setting. Furthermore, institutional involvement varied due to policy and cultural contingencies and power dependencies. 相似文献
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Leah A. Lievrouw 《The Information Society》2000,16(2):155-159
This essay focuses on universal service and the Internet as means to support social and political participation. The emphasis on access to telecommunications systems in conventional approaches to universal service is contrasted with access to content. A model of the information environment is described that accounts for the roles of content and conduit, both of which are necessary conditions to achieve true access. A method is outlined for employing information indicators to observe or measure the information environment. 相似文献
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Puay Tang 《The Information Society》1998,14(1):19-31
The increasing prospects of digital piracy has prompted the perceived need by electronic publishers to adopt technical systems of protection, and governments to reform their copyright laws. This article is a preliminary study of the management of intellectual property by electronic publishers, defined as those involved in the production of online databases, and CD-ROMs. It focuses on three main issues: (1) how electronic publishers view the increasing threat of piracy; (2) the methods of protection employed to protect intellectual property in digital format; and (3) the importance of technological protection of intellectual property in electronic publications. The analysis is based on a sample of 23 UK electronic publishers. The interviews revealed an interesting assortment of protection methods and did not show that technological protection was a preferred way. Instead, the means of protection, in addition to copyright law, comprised niche markets, pricing, trust, bad publicity, and nontechnical and technical means. 相似文献