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71.
Differentiating the binding properties of applied lectins should facilitate the selection of lectins for characterization of glycoreceptors on the cell surface. Based on the binding specificities studied by inhibition assays of lectin-glycan interactions, over twenty Gal and/or GalNAc specific lectins have been divided into eight groups according to their specificity for structural units (lectin determinants), which are the disaccharide as all or part of the determinants and of GalNAc alpha 1-->Ser (Thr) of the peptide chain. A scheme of codes for lectin determinants is illustrated as follows: (1) F (GalNAc alpha 1-->3GalNAc), Forssman specific disaccharide--Dolichos biflorus (DBL), Helix pomatia (HPL) and Wistaria floribunda (WFL) lectins. (2) A (GalNAc alpha 1-->3 Gal), blood group A specific disaccharide--Codium fragile subspecies tomentosoides (CFT), Soy bean (SBL), Vicia villosa-A4 (VVL-A4), and Wistaria floribunda (WFL) lectins. (3) Tn (GalNAc alpha 1-->Ser (Thr) of the protein core)--Vicia villosa B4 (VVL-B4), Salvia sclarea (SSL), Maclura pomifera (MPL), Bauhinia purpurea alba (BPL) and Artocarpus integrifolia (Jacalin, AIL). (4) T (Gal beta 1-->3GalNAc), the mucin type sugar sequences on the human erythrocyte membrane(T alpha), T antigen or the disaccharides at the terminal nonreducing end of gangliosides (T beta)--Peanut (PNA), Bauhinia purpurea alba (BPL), Maclura pomifera (MPL), Sophora japonica (SJL), Artocarpus lakoocha (Artocarpin) lectins and Abrus precatorius agglutinin (APA).(5) I and II (Gal beta 1-->3(4)GlcNAc)--the disaccharide residue at the nonreducing end of the carbohydrate chains derived from either N- or O-glycosidic linkage--Ricinus communis agglutinin (RCA1), Datura stramonium (TAL, Thorn apple), Erythrina cristagalli (ECL, Coral tree), and Geodia cydonium (GCL). (6) B (Gal alpha 1-->3Gal), human blood group B specific disaccharide--Griffonia(Banderiaea) simplicifolia B4 (GSI-B4). (7) E (Gal alpha 1-->4Gal), receptors for pathogenic E. coli agglutinin, Shiga toxin and Mistletoe toxic lectin-I (ML-I) and abrin-a.  相似文献   
72.
Because changes in intracellular Ca2+ affect progression through the mitotic cell cycle, we investigated the role of Ca2+-binding proteins in regulating cell cycle progression. Evidence was found demonstrating that the activation of Ca2+/calmodulin-dependent protein kinase (CaM kinase) inhibits cell cycle progression in small cell lung carcinoma (SCLC) cells. We also demonstrated that SCLC cells express both CaM kinase type II (CaMKII) and CaM kinase type IV (CaMKIV). Five independent SCLC cell lines expressed proteins reactive with antibody to the CaMKII beta subunit, but none expressed detectable proteins reactive with antibody to the CaMKII alpha subunit. All SCLC cell lines tested expressed both the alpha and beta isoforms of CaMKIV. Immunoprecipitation of CaMKII from SCLC cells yielded multiple proteins that autophosphorylated in the presence of Ca2+ / calmodulin. Autophosphorylation was inhibited by the CaMKII(281-302) peptide, which corresponds to the CaMKII autoinhibitory domain, and by 1-[N,O-bis(5-isoquinolinesulfonyl)-N-methyl-L-tyrosyl]-4- phenylpiperazine (KN-62), a specific CaM kinase antagonist. Influx of Ca2+ through voltage-gated Ca2+ channels stimulated phosphorylation of CaMKII in SCLC cells, and this was inhibited by KN-62. Incubation of SCLC cells of KN-62 potently inhibited DNA synthesis, and slowed progression through S phase. Similar anti-proliferative effects of KN-62 occurred in SK-N-SH human neuroblastoma cells, which express both CaMKII and CaMKIV, and in K562 human chronic myelogenous leukemia cells, which express CaMKII but not CaMKIV. The expression of both CaMKII and CaMKIV by SCLC cells, and the sensitivity of these cells to the anti-proliferative effects of KN-62, suggest a role for CaM kinase in regulating SCLC proliferation.  相似文献   
73.
The ability of morphine to modify sucrose palatability was assessed by the taste reactivity test. In Experiment 1, rats were injected with morphine (0.0, 0.5, 2.0, and 10.0 mg/kg, subcutaneously), 30 min before receiving a 10-min intraoral infusion of 2% or 20% sucrose solution. A dose of 2.0 mg/kg morphine enhanced ingestive reactions elicited by both concentrations of sucrose solution. In Experiment 2, the interval between morphine pretreatment and the taste reactivity test was manipulated. Rats given 2.0 mg/kg morphine 30 or 120 min before testing displayed enhanced ingestive reactions elicited by 20% sucrose solution during the first 5 min of a 10-min test. The results support the hypothesis that morphine enhances the hedonic assessment of sucrose solution.  相似文献   
74.
BACKGROUND: Inhibition of thrombin by either the indirect thrombin inhibitor heparin or by more potent direct thrombin inhibitors such as hirudin reduces thrombus formation after arterial injury. The present study was designed to determine if a fibrin-specific thrombin inhibitor could, by local thrombin inhibition, prevent thrombosis more effectively. METHODS AND RESULTS: We first studied antithrombotic potency in vitro, comparing fibrin-targeted hirudin (recombinant hirudin covalently linked to the Fab' fragment of the anti-fibrin monoclonal antibody 59D8) to recombinant hirudin in baboon plasma. Fibrin-targeted hirudin was nine times more effective than recombinant hirudin in inhibiting fibrin deposition on experimental clot surfaces in baboon plasma (P < .01). The potency of fibrin-targeted hirudin was then compared with that of recombinant hirudin in a baboon model of thrombus formation. 111In-labeled platelet deposition was measured in a synthetic graft segment of an extracorporeal arteriovenous shunt in control animals and in animals receiving either fibrin-targeted hirudin or hirudin. In these experiments, fibrin-targeted hirudin was 10-fold more potent than hirudin in inhibiting platelet deposition and thrombus formation (P < .05). CONCLUSIONS: These data indicate that targeting a thrombin inhibitors such as hirudin to an epitope present in thrombi results in increased antithrombotic potency.  相似文献   
75.
以硝酸盐为原料,乙二胺四乙酸(EDTA)为络合剂,乙烯乙二醇为交联剂,利用Pechini法制备了名义组分为BiSrCaCu8+δ(Bi-2212)超导粉体。通过X射线衍射(XRD)、标准四引线法等手段,研究了络合剂、交联剂用量及油浴温度、时间对超导粉体物相、结晶性及电学性能的影响。实验结果表明:不同凝胶化条件制备的超导粉体,均保持较高的相纯度;但工艺参数的改变对Bi-2212粉体的结晶性与电学性能影响显著,其临界转变温度Tc,0相差7.3K。  相似文献   
76.
以5种不同聚乙烯醇/聚二甲基二乙烯氯化铵配比制备了用于电透析脱盐的阴离子自立交换膜,并考察3种不同热处理温度对膜含水率、膜电荷密度、真实迁移数及膜面电阻的影响。实验结果表明:膜的含水率随聚二甲基二乙烯氯化铵含量CPC的增加而增加,随热处理温度的增加而降低;在CPC为30 wt%,热处理温度为180℃时,阴离子交换膜的膜面电阻最低,为3.04Ωcm2;在CPC为30 wt%,热处理温度为180℃时,阴离子交换膜的真实迁移数达到0.99;在CPC为20 wt%,热处理温度为180℃时,阴离子交换膜的膜电荷密度值为1.14 mol dm-3。  相似文献   
77.
喇元  何宝声  王红斌  朱文俊 《广东电力》2012,25(6):69-72,95
分压屏对套管内部电场分布存在一定程度的影响,尤其在分压屏极板两端的电场容易产生畸变,给套管的安全稳定运行带来一定隐患。针对此,通过插值拟合的方式,建立分压屏极板边缘电场强度与极板尺寸之间的函数关系,并根据该函数关系优化分压屏极板尺寸,使套管内部电场分布尽量均匀、合理。采用大型有限元计算软件Ansys对套管内部电场进行仿真计算,结果表明,分压屏极板的位置及尺寸优化后能够满足要求,可使套管内部最大电场强度值降低45%,并有效改善分压屏极板两端的电场畸变问题。  相似文献   
78.
Identification of the aging condition and the failure probability of oil-paper insulation in transformer is important for improving the reliability of electric power transmission system and applying life cycle cost (LCC) management to electrical equipment. Based on data obtained in a series of multi-accelerated-aging experiments, two approaches for calculating failure probability of oil-paper insulation were compared in aspects of degree of polymerization (DP) and condition ranking. In the experiments, mineral oil and cellulose paper are sub- jected to electrical and thermal stresses, and several parameters, including dissolved gases’ volume fraction, furfural content, moisture content, and degree of polymerization, are measured after the aging process. Results show that weight of carbon oxide, which has a close relationship with cellulose paper degradation, is much higher in DP model than in condition ranking model. Moreover, it is concluded that DP model is more practically accurate than condition ranking model, because aging of cellulose paper rather than mineral oil is the key and critical factor of oil-paper insulation aging.  相似文献   
79.
对发电机绝缘局部放电量的测量是考核其绝缘状况的重要手段,但传统的测量方法由于受到试验现场的强电磁干扰,常常无法进行有效的测量,因而难以对发电机的绝缘状况做出准确的判断.本文提出了一种基于双电容耦合的发电机局部放电离线式测量新方法,通过设计两个电容的耦合性能及其传递过来的信号时差关系,可以有效地将发电机外的放电信号以及其他各类干扰信号予以消除,因而具有很强的抗干扰能力.现场的实际试验表明,该方法不仅使发电机的局部放电测量易于进行,还大大提高了发电机局部放电测量的准确度.  相似文献   
80.
Zu, Cu, Cd, Pb and Hg salts blocked the cleavage divisions in the sea urchin embryos and, in lesser concentrations, affected gastrulation and induced postgastrulation defects. The early embryo- and cytotoxic effects of Zn salts appear to be based on the inhibition of protein synthesis. Unithiol exerted a protective effect. All salts under study inhibited protein synthesis in the Ehrlich's ascite carcinoma and ascite hepatoma 22a cells; unithiol and other suldhydryl compounds exerted in this case a good protective effect against Cd salts only.  相似文献   
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