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81.
二维共享内存多点传送ATM的交换结构 总被引:1,自引:0,他引:1
王琳珠 《吉林大学学报(信息科学版)》2002,20(3):37-42
为达到多点传送业务需要,提出一种高性能的多点传送ATM的交换系统。利用它能够更容易地建立和释放多点呼叫,并能很容易地解决多点传送信元的过流情况。该系统只保留一个地址即可通过一种覆盖方案来减少多点传送信元复制进程的时延。复制因数和扩展度可以调整与多点传送平均容量一致,即使多点传送的平均容量很大,开销也会很小。 相似文献
82.
83.
E. Cohen-Hillel R. Mintz T. Meshel B.-Z. Garty A. Ben-Baruch 《Cellular and molecular life sciences : CMLS》2009,66(5):884-899
The chemokine CXCL8 is a powerful inducer of directional cell motility, primarily during inflammation. In this study, we found
that CXCL8 stimulation led to paxillin phosphorylation in normal neutrophils, and that both CXCL8 receptors (CXCR1 and CXCR2)
mediated CXCL8-induced paxillin phosphorylation. In CXCR2-transfected cells, the process depended on Gαi and Gαs coupling to CXCR2. Dominant negative (DN) paxillin increased CXCL8-induced adhesion and migration, indicating that endogenous
paxillin keeps migration at submaximal levels. Furthermore, using activating antibodies to β1 integrins, analyses with focal
adhesion kinase (FAK) DN variant (FRNK) and co-immunoprecipitations of FAK and paxillin, we found that β1 integrin ligation
cooperates with CXCL8-induced stimulation, leading to FAK activation and thereafter to FAK-mediated paxillin phosphorylation.
Our findings indicate that paxillin keeps directional motility at a restrained magnitude, and suggest that perturbations in
its activation may lead to chemotactic imbalance and to pathological conditions associated with excessive or reduced leukocyte
migration.
R. Mintz, T. Meshel: These authors contributed equally to this work.
Received 31 July 2008; received after revision 14 December 2008; accepted 16 December 2008 相似文献
84.
生物技术专业的实验教学对培养高素质的生物技术专业人才至关重要,要做好生物技术专业的实验教学,对生物技术综合实验室进行科学化管理势在必行.文中指出了我校生物技术实验教学的现状,并提出了实验室硬件建设、制度化建设、决策民主化、信息电子化、功能分区模块化及责任具体化等管理对策. 相似文献
85.
86.
Bastian P Lang K Niggemann B Zaenker KS Entschladen F 《Cellular and molecular life sciences : CMLS》2005,62(1):65-76
The migration of cells is a complex regulatory process which results in the generation of motor forces through the reorganization of the cytoskeleton. Here we present a comparative study of the expression and involvement of myosin in the regulation of the physiological migration of leukocytes and the pathological migration of tumor cells. We show that the involvement of myosin in the migration is distinct in these two cell types. In leukocytes, the activity of non-muscle myosin II is essential for both the spontaneous (matrix-induced) migration and the migration induced by ligands to G protein-coupled receptors, i.e. chemokines and neurotransmitters. In contrast, spontaneous tumor cell migration is largely independent of non-muscle myosin II activity, whereas the norepinephrine-induced migration is completely inhibited by either direct inhibition of non-muscle myosin II or of the kinases phosphorylating the myosin light chain, namely ROCK or the calcium/calmodulin-dependent myosin light-chain kinase.Received 31 August 2004; accepted 26 October 2004 相似文献
87.
D.T.A. Lamport 《Cellular and molecular life sciences : CMLS》2001,58(10):1363-1385
This review of the living cell wall [1] and its protein components is in two parts. The first is anecdotal. A personal account
spanning over 40 years research may perhaps be an antidote to one stereotypical view of scientists as detached and humorless.
The second part deals with the meaning of function, particularly as it applies to hydroxyproline-rich glycoproteins. Function
is a difficult word to define objectively. However, with help from such luminaries as Humpty Dumpty: "A word means what I
want it to mean, neither more nor less," and Wittgenstein: "Giving examples of usage ... is the only way to talk about meaning,"
it is possible to construct a ziggurat representing increasingly complex levels of organization from molecular structure to
ecology. Forty years ago I suggested that hydroxyproline-rich structural proteins played a key role in cell wall functioning.
But because the bulk of the wall is carbohydrate, there has been an understandable resistance to paradigm change. Expansins,
paradoxically, contribute greatly to this resistance because their modus operandi as cell-wall-loosening proteins is based
on the idea that they break hydrogen bonds between polysaccharide chains allowing slippage. However, this view is not consistent
with the recent discovery [Grobe et al. (1999) Eur. J. Biochem 263: 33-40] that β-expansins may be proteases, as it implies that the extensin network is not a straightjacket but a substrate for expansin
in muro. Such a direct role for extensins in both negative and positive regulation of cell expansion and elongation may constitute
a major morphogenetic mechanism operating at all levels of plant growth and development. 相似文献
88.
89.
化疗药环磷酰胺对癌细胞的细胞周期影响和诱导凋亡作用的研究 总被引:3,自引:0,他引:3
目的 研究化疗药环磷酰胺对癌细胞的细胞周期、DI值、PI值等某些生物学特性的影响及其诱导癌细胞凋亡的作用。方法 用BALB/c小鼠 ,荷腹水性肝癌 ,经腹腔给药CTX后 ,抽取腹水癌细胞进行形态学观察和流式细胞光度分析研究。结果 在环磷酰胺的作用下 ,癌细胞发生了凋亡 ,形态上观察到了许多凋亡细胞和凋亡小体 ;流式细胞光度分析发现 ,药物作用后 ,细胞周期发生了巨大变化 ,大多数癌细胞被阻断在G2M期 ,而G1期癌细胞明显减少 (P <0 0 5~P <0 0 1) ;同时 ,给药组癌细胞的DNA值和PI值亦明显增高 (P <0 0 5~P <0 0 1)。结论 环磷酰胺能够诱导癌细胞凋亡 ,而且对癌细胞的细胞周期一般规律有较大的干扰。分析认为这对癌症临床治疗会有一定启示。 相似文献
90.
郭耀 《西北民族学院学报》2014,(3):40-45
为探究合成化合物溴代香豆素的生物活性,将该化合物作用于胃癌细胞进行了体外研究.本研究分别采用磺酰罗丹明染色法和生长曲线法研究了药物的细胞毒活性和癌细胞的致死过程.以彗星电泳技术和瑞士—吉姆萨染色法观察了化合物对细胞核形态变化和核酸损伤效应,最后以琼脂糖凝胶电泳法检测了药物对细胞总DNA的影响.结果显示,溴代香豆素对胃癌细胞具有显著的细胞毒活性,其IC50为21.56μg/m L.药物对细胞的增殖抑制效应和致死效应都具有显著的时间—剂量依赖性.药物作用癌细胞后可引起细胞核形态变化和染色质凝集断裂,并损伤细胞DNA,在电泳中呈梯度降解状态.结果表明,溴代香豆素对胃癌细胞的生长与增殖具有显著的细胞毒活性,并能诱导胃癌细胞发生凋亡. 相似文献