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71.
D. DiFrancesco F. Porciatti I. S. Cohen 《Cellular and molecular life sciences : CMLS》1991,47(5):449-452
Summary The isolation of ionic fluxes contributing to electric currents through cell membranes often requires block of other undesired components which can be achieved, among others, by divalent cations. Mn2+ and Ba2+ are often used, for example, to block Ca and K currents. Here we have investigated the effects of these two cations on the properties of the hyperpolarization-activated pacemaker current if, in rabbit sino-atrial node myocytes, as obtained by voltage clamp analysis. We find that 2 mM Mn2+ shifts the if activation curve by 3.2±0.3 mV towards more positive values. However, when 1 mM Ba2+ is also added, the positive shift is more than halved (1.3±0.2 mV). We find, too, that in the absence of blocking cations the ACh-induced if inhibition is slightly higher than in their presence. These results indicate that the alteration of if kinetic properties by Ba2+ plus Mn2+-containing solutions is minimal. 相似文献
72.
Profiling of the secreted proteins during 3T3-L1 adipocyte differentiation leads to the identification of novel adipokines 总被引:3,自引:0,他引:3
Wang P Mariman E Keijer J Bouwman F Noben JP Robben J Renes J 《Cellular and molecular life sciences : CMLS》2004,61(18):2405-2417
Adipose tissue is an endocrine organ capable of secreting a number of adipokines with a role in the regulation of
adipose tissue and whole-body metabolism. We used two-dimensional gel electrophoresis combined with mass spectrometry to
profile the secreted proteins from (pre)adipocytes. The culture medium of 3T3-L1 cells during adipocyte differentiation
was screened, and 41 proteins that responded to blocking of secretion by 20°C treatment and/or brefeldin A treatment
were identified. Prohibitin, stress-70 protein, and adhesion-regulating molecule 1 are reported for the first time as
secreted proteins. In addition, procollagen C-proteinase enhancer protein, galectin-1, cyclophilin A and C, and SF20/IL-25
are newly identified as adipocyte secreted factors. Secretion profiles indicated a dynamic environment including an
actively remodeling extracellular matrix and several factors involved in growth regulation.Received 15 June 2004; received after revision 26 July 2004; accepted 2 August 2004 相似文献
73.
Joyce S 《Cellular and molecular life sciences : CMLS》2001,58(3):442-469
Cellular and humoral immune mechanisms recruited to defend the host from infectious agents depend upon the early immune events
triggered by antigen. The cytokine milieu within which the immune response matures is the most important of many factors that
govern the nature of the immune response. Natural T cells, whose function is controlled by CD1d molecules, are an early source
of cytokines that can bestow type 1 or type 2 differentiative potential upon helper T lymphocytes. This review attempts to
illuminate the glycolipid antigen presentation properties of CD1d, how CD1d controls the function of natural T cells and how
CD1d and natural T cells interact to jump start the immune system. CD1d is postulated to function as a sensor, sensing alterations
in cellular lipid content by virtue of its affinity for such ligands. The presentation of a neo-self glycolipid, presumably
by infectious assault of antigen-presenting cells, activates natural T cells, which promptly release pro-inflammatory and
anti-inflammatory cytokines and jumpstart the immune system.
Received 10 July 2000; received after revision 16 October 2000, accepted 16 November 2000 相似文献
74.
Leiman PG Kanamaru S Mesyanzhinov VV Arisaka F Rossmann MG 《Cellular and molecular life sciences : CMLS》2003,60(11):2356-2370
Bacteriophage T4 is one of the most complex viruses. More than 40 different proteins form the mature virion, which consists of a protein shell encapsidating a 172-kbp double-stranded genomic DNA, a tail, and fibers, attached to the distal end of the tail. The fibers and the tail carry the host cell recognition sensors and are required for attachment of the phage to the cell surface. The tail also serves as a channel for delivery of the phage DNA from the head into the host cell cytoplasm. The tail is attached to the unique portal vertex of the head through which the phage DNA is packaged during head assembly. Similar to other phages, and also herpes viruses, the unique vertex is occupied by a dodecameric portal protein, which is involved in DNA packaging.Received 18 February 2003; received after revision 16 April 2003; accepted 9 May 2003 相似文献
75.
何伟 《中央民族大学学报(自然科学版)》2003,12(3):227-234
本文首先介绍了模拟退火算法,给出了它的物理和数学解释.另外首次对文献[5]中提出的推广的与时间无关的噪声算法(TINA)进行了严格的理论讨论,说明了当参数α>0 5时算法依概率收敛到一个全局极值点;而当α=0 5时,随机动力系统可能发生分支现象. 相似文献
76.
混凝土倒"T"形叠合板承载力的计算方法 总被引:2,自引:2,他引:0
提出一种只发生"部分叠合"的新型混凝土倒"T"形叠合板结构形式.采用肋部厚度已达最终设计厚度的倒"T"形截面预制板,使之能直接承受后浇叠合层混凝土的自重和施工活荷载,节省模板和临时支撑;再根据倒"T"形叠合板的构造特点和试验研究及实际工程应用,提出了这种新型叠合板以倒"T"形板为跨中弯矩的承载主体,后浇叠合层混凝土仅参与正常使用阶段工作的基本假定,建立了计算内容与整浇梁板相同的、简单可靠的承载力计算方法.由于计算过程中将仅发生部分叠合的后浇叠合层混凝土的实际结构功能予以降低,故设计者可根据实际工程情况赋予倒"T"形预制板凹槽内的后浇叠合层混凝土某些附加的有益功能,如保温、防渗、轻质等,从而进一步提高该结构的安全性和适用性,更有利于这种新型叠合板结构的推广应用. 相似文献
77.
TANG Zhiwen WANG Kemin TAN Weihong LI Jun LIU Lingfeng GUO Qiuping MENG Xiangxian HUANG Shasheng LI Du & LUO Weifang State Key Laboratory of Chemo/Biosensing Chemometrics Institute of Biological Technology College of Chemistry Chemical Engi-neering Hunan University Changsha China Correspondence should be addressed to Wang Kemin 《科学通报(英文版)》2003,48(12):1215-1218
The replication, ligation and repair of nucleic acids are essential life processes that based the survival, pro-creation and evolution of creatures. These interactions involving proteins (enzymes) and nucleic acids have fas-cinated great interest of scientists[1]. The nucleic acids ligation has been revealed that it is catalyzed by ligase and co-enzyme (ATP or NAD)[2—4]. Along with in-depth re-search, the nucleic acids ligation becomes a significant and common tool employed in bioengineerin… 相似文献
78.
Lambert方程在轨道拦截和初始轨道确定起着重要作用。求解Lambert方程的传统算法主要有Newton迭代方法和超几何级数展开方法等,但这些算法都有一定的局限性(如有可能出现迭代收敛过慢,级数展开收敛性问题)。采用进化-模拟退火算法(EA-SA)算法求解Lambert方程,其中进化算法具有全局搜索能力,而模拟退火具有局部锁搜索能力。该方法克服了某些情况下梯度下降法有时收敛过慢和超几何级数不收敛的缺点,并具有通用性,便于操作和理解。通过仿真计算对比表明,EA-SA具有普适性,而且精度优于其它两种算法。 相似文献
79.
80.
辽宁省工业旅游资源丰富,大力发展工业旅游,既能丰富旅游内涵,又可加快辽宁老工业基地振兴的步伐.本文通过对辽宁工业旅游的SWOT分析,认为辽宁工业旅游既有优势、机会,也存在劣势和威胁,只有抓住机遇,迎接挑战,采取措施,才能使辽宁省的工业旅游实现可持续发展,从而为老工业基地的振兴做出贡献. 相似文献