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61.
申屠军 《安徽卫生职业技术学院学报》2004,3(4):84-85
在建设学习型社会和新课改的新形势下,高中生物教师应确立三种意识:"学习意识、信息意识、科研意识",不断提高自身素质,使自己成为一名学者型、研究型的现代生物教师. 相似文献
62.
63.
大白鼠游泳输出功测定仪的研制和疲劳方程Y=A+B/T的建立 总被引:1,自引:0,他引:1
研制了可以直接连续测量大鼠游泳输出功率的仪器,建立了一个理想的动物模型,通过分析对功率曲线进行函数拟合,得出了代表疲劳发生、作功能力下降的双曲线方程,通过分析衰竭时间和功、功率等参数的关系提出了衰竭阈概念。 相似文献
64.
65.
Michael Schirner Frank Herzberg Roland Schmidt Michael Streit Michael Schoning Michael Hummel Christine Kaufmann Eckhard Thiel Ernst-Dieter Kreuser 《Clinical & experimental metastasis》1997,16(5):427-435
The integrin 51 seems to be the most relevant receptor of tumor cells for binding to fibronectin. Although numerous studies suggest a role of tumor cell fibronectin interaction in tumor metastasis, differential integrin expression on tumor cells has, however, not been correlated with metastatic capabilities. We addressed this question by transfection of the integrin 51 cDNA into HT-29 human colon carcinoma cells which led to de novo expression of functional integrin 51. Similar to other reports, expression of the integrin 51 in HT-29 tumor cells exerted an inhibitory action on cell proliferation as indicated in our study by formation of fewer colonies in soft agar. The tumor growth inhibitory property of the integrin 51 was also shown by reduction of subcutaneous xenograft growth in nude mice to approximately 50% of that of control transfectants. For the first time, we found that several clones of integrin 5 subunit transfectants displayed dramatically reduced formation of lung colonies and cutaneous metastasis after intravenous injec-tion into nude mice. While most animals inoculated with control transfectant cells formed macroscopically visible lung colonies ranging from 12.6 ± 2.6 to 22.0 ± 6.6 (mean colony number ± SEM), mice inoculated with HT-29 cell clones expressing the integrin a5b1 were almost completely free of lung colonies (ranging from 0.0 ± 0 to 0.2 ± 0.1). Our results imply that integrin 51 expression inhibits circulating tumor cells in pursuing late steps of the metastatic process as represented by the artificial metastasis (lung colonisation) model. © Rapid Science Ltd. 相似文献
66.
痢疾杆菌免疫小鼠的GALT中T淋巴细胞亚群的应答状态 总被引:1,自引:2,他引:1
以鼠伤寒杆菌G30株为对照,应用间接免疫荧光法检测了痢疾杆菌福氏2a经口服及腹腔免疫后,小鼠派伊尔氏(PP)节结、肠系膜淋巴结(MLN)及脾脏(SPt)中L3T4~+、Lyt2~+T细胞亚群的变化;并以MTT比色法测定了ConA诱导的淋巴细胞增殖反应。实验发现:无论是口服还是腹腔途径,这两种细菌都诱导出基本相似的T淋巴细胞反应,即L3T4亚群在PP及MLN中均有显著升高,而Lyt2亚群均无明显变化;口服途径仅PP淋巴细胞的增殖反应有明显升高,腹腔途径主要为MLN出现淋巴细胞显著的增殖反应。提示:在痢疾菌感染免疫中以L3T4亚群起主要作用;PP作为粘膜免疫的诱导部位;经口途径主要诱导肠道局部淋巴细胞的免疫应答,经腹腔途径虽能诱导多部位免疫应答但有否抗粘膜感染保护作用尚待研究。 相似文献
67.
Werner M Mattis A Aubele M Cummings M Zitzelsberger H Hutzler P Höfler H 《Virchows Archiv : an international journal of pathology》1999,435(5):469-472
The 20q13 region harboring recently described putative oncogenes is frequently amplified in invasive ductal carcinoma (IDC).
The aim of this study was to examine the 20q13 copy number in intraduct hyperplasia (IH), atypical duct hyperplasia (ADH),
and ductal carcinoma in situ (DCIS) adjacent to IDC. In 5 patients, comparative genomic hybridization (CGH) after laser microdissection
revealed 20q13 amplification in four of five cases of IH, in all of three cases of IH with atypia, all five of DCIS, and all
five of IDC. Fluorescence in situ hybridization (FISH) confirmed the amplification at 20q13.2 in IH in the two specimens analyzed.
The amplification rate, however, was higher in DCIS and IDC. In phenotypically normal ductal epithelium normal values were
found for 20q13 copy number by FISH (n=2) and CGH (n=5). Although the number of cases presented here is small, our results suggest that mutations in the 20q13.2 region in IH
may be associated with accelerated proliferation and hyperplasia of the ductal epithelium. Progression to DCIS and ICD is
accompanied by a further increase in the 20q13.2 copy number.
Received: 17 March 1999 / Accepted: 22 June 1999 相似文献
68.
M. Vandenbranden J.L. de Coen R. Jeener L. Kanarek J.M. Ruyschaert 《Molecular immunology》1981,18(7):621-631
Interactions between rabbit-γ-immunoglobulins and model membranes (lipid monalayers, planar lipid bilayers, liposomes) have been investigated. No significant interaction was observed with immunoglobulins. However, immunoglobulins dialysed first vs aqueous buffer having pH 2 or 3 and then dialysed against pH 7 buffer presumably adopt a new conformation which allows their bindings to model membranes. This binding is hydrophobic and the immunoglobulin region interacting with the lipid acyl chains is probably located in the heavy chain, as suggested by labelling in this region by a photosensitive probe previously incorporated into the lipid hydrophobic core. Cleavage at the hinge region by papain or pepsin, or heating above 38°C, induces the loss of the hydrophobic conformation responsible for hydrophobic bindings. The binding capacity of immunoglobulins heated above 38°C is restored after momentary dialysis at pH 2. The possible existence of two Ig isomers is discussed in relation to the mechanism of γ-immunoglobulin passage through the endoplasmic membrane and fixation into the plasma membrane. 相似文献
69.
In Ascaris muscle mitochondria the major respiratory chain-linked phosphorylation activity is accomplished by a NADH-linked reduction of fumarate to succinate. Oxygen can also be employed as a terminal electron acceptor via a cyanide- and salicyl-hydroxamate-resistant terminal oxidase. As in fumarate-dependent electron transport this process appears to be coupled to energy conservation at phosphorylation site I. The branchpoint from which electrons are taken from the main respiratory chain to either the alternative oxidase or fumarate reductase is likely to be on the oxygen side of the NADH dehydrogenase segment.Malate and succinate are the only substrates which appreciably support respiration in the mitochondrion of the nematode. Regardless of the presence or absence of oxygen malate is utilized by an oxidation-reduction reaction resulting in the formation of pyruvate, acetate, succinate, propionate and CO2. In addition, aerobically, hydrogen peroxide is formed as the product of oxygen reduction. Succinate accumulation was found to be significantly higher in the anaerobic as compared to the aerobic incubation mixtures. This effect was accompanied by an increase in anaerobic malate consumption. ATP generation and the formation of pyruvate, acetate and propionate were found to be similar in the presence and absence of oxygen.In malate-supported respiration of intact Ascaris mitochondria reducing equivalents (NADH) are produced exclusively through pyruvate and acetate formation. These enzymatic reactions are functionally coupled to the electron transport-linked reductions of fumarate to succinate and oxygen to hydrogen peroxide, respectively. In accordance with the position of the redox potentials of the fumarate/succinate and O2/H2O2 couples, anaerobic and aerobic respiration was found to be associated with relatively low energy conservation efficiencies. Thus one molecule of ATP was conserved per 2e? transferred to fumarate or oxygen, respectively. No evidence could be obtained for a significant activity of energy conservation sites II and III and electron transfer through the alternative oxidase pathway was shown not to be coupled to phosphorylation. 相似文献
70.
Daniel F. Legler Marcel Loetscher Simon A. Jones Clemens A. Dahinden Michel Arock Bernhard Moser 《European journal of immunology》1996,26(4):753-758
The proteolytic cleavage product of complement component 3, (C3a), like C4a and C5a, is a potent anaphylatoxin and induces the production of inflammatory mediators in phagocytes. Notably, mast cells respond to C3a with the release of vasoactive substances, including histamine. We have examined the function and receptor binding of C3a in a human leukemic mast cell line, HMC-1. Similar to chemoattractant agonists in leukocytes, C3a induced rapid cytosolic free calcium concentration increases in HMC-1 cells. EGTA did not diminish this response, indicating that mobilizable Ca2+ was from intracellular stores. Receptors for C3a in HMC-1 cells couple in part to Bordetella pertussis toxin-sensitive G-proteins and, therefore, appear to belong to the family of serpentine receptors that require G-proteins for signal transduction. HMC-1 cells express two types of C3a receptors, C3aR1 and C3aR2, that were shown to bind 125I-C3a with high-(Kd1 = 2.1–4.8 nM) or low-affinity (Kd2 = 30–150 nM), and both receptors are expressed at high level: 3 × 105–6 × 105 C3aR1/cell and 5 × 105–2.3 × 106 C3aR2/cell. Results from cross-linking experiments with 125I-C3a fully agree with the presence of two different classes of C3a receptors in HMC-1 cells. Two membrane proteins with apparent molecular masses of 54–61 kDa (p57) and 86–107 kDa (p97) could be covalently modified with 125I-C3a, and this cross-linking was inhibited with an excess of unlabeled C3a. Many of the known agonists for leukocytes including 13 chemokines (IL-8, NAP-2, GROα, ENA-78, IP10, PF4, MCP-1, 2 and 3, RANTES, MIP-1α, MIP-1β and 1309), three neuropeptides (neuropeptide Y, somatostatin and calcitonin), as well as C5a, did not activate HMC-1 cells, indicating that C3a is one of a few protein ligands for which this cell line expresses specific receptors. The apparent selectivity for C3a and the abundant expression of C3a receptors make the HMC-1 cell line an excellent choice for the cloning of the receptor genes. 相似文献