991 resultados para 8-hydroxyquinolinate derivatives


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The workshop's objective was to provide information to improve a regional Ecopath with Ecoism (EwE) model.The workshop described the basis and principles underlying the software, encompassing the basics of Ecopath to Ecospace, economics and management strategy evaluation.

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报道了云南8种树蛙的染色体组型, 并对目前所已知的树蛙种类的染色体组型进行了比较。

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Sertoli cells play a central role in the control and maintenance of spermatogenesis. Isolated Sertoli cells of mouse and rat testes have been shown to secrete plasminogen activator (PA) and a plasminogen activator inhibitor type-1 (PAI-1) in culture. In this study, we have investigated the hormonal regulation of PA and PAI-1 activities in cultured monkey Sertoli cells. Sertoli cells (5x10(5) cells/well) isolated from infant rhesus monkey testes were preincubated at 35 degrees C for 16 h in 24-well plates precoated with poly(D-lysine) (5 mu g/cm(2)) in 0.5 mi McCoy's 5a medium containing 5% of fetal calf serum and further incubated for 48 h in 0.5 mi serum-free medium with or without various hormones or other compounds, PA as well as PAI-1 activities in the conditioned media were assayed by fibrin overlay and reverse fibrin autography techniques respectively. The Sertoli cells in vitro secreted only tissue-type PA (tPA), no detectable amount of urokinase-type PA (uPA) could be observed, Monkey Sertoli cells were also capable of secreting PAI-1, Immunocytochemical studies indicated that both tPA and PAI-1 positive staining localized in the Sertoli cells, spermatids and residual bodies of the seminiferous epithelium; Northern blot analysis further confirmed the presence of both tPA and PAI-1 mRNA in monkey Sertoli cells. Addition of follicle-stimulating hormone (FSH) or cyclic adenosine monophosphate (cAMP) derivatives or cAMP-generating agents and gonadotrophin-releasing hormone (GnRH) agonist or phorbol ester (PMA) to the cell culture significantly increased tPA activity. PAI-1 activity in the culture was also enhanced by these reagents except 8-bromo-dibutyryl-cAMP, forskolin and 3-isobutyl-1-methylxanthin (MIX) which greatly stimulated tPA activity, whereas decreased PAI-1 activity, implying that neutralization of PAI-1 activity by tile high level of tPA in the conditioned media may occur. These data suggest that increased intracellular signals which activate protein kinase A (PKA), or protein kinase C (PKC) can modulate Sertoli cell tPA and PAI-1 activities, The concomitant induction of PA and PAI-1 by the same reagents in the Sertoli cells may reflect a finely tuned regulatory mechanism in which PAI-1 could limit the excession of the proteolysis.

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To understand pharmacophore properties of pyranmycin derivatives and to design novel inhibitors of 16S rRNA A site, comparative molecular field analysis (CoMFA) approach was applied to analyze three-dimensional quantitative structure-activity relationship (3D-QSAR) of 17 compounds. AutoDock 3.0.5 program was employed to locate the orientations and conformations of the inhibitors interacting with 16S rRNA A site. The interaction mode was demonstrated in the aspects of inhibitor conformation, hydrogen bonding and electrostatic interaction. Similar binding conformations of these inhibitors and good correlations between the calculated binding free energies and experimental biological activities suggest that the binding conformations of these inhibitors derived from docking procedure were reasonable. Robust and predictive 3D-QSAR model was obtained by CoMFA with q(2) values of 0.723 and 0.993 for cross-validated and noncross-validated, respectively. The 3D-QSAR model built here will provide clear guidelines for novel inhibitors design based on the Pyranmycin derivatives against 16S rRNA A site. (c) 2005 Elsevier B.V. All rights reserved.

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We analyzed n-mers (n=3-8) in the local environment of 8,249,446 human SNPs and compared their distribution with that in the genome reference sequences. The results revealed that the short sequences, which contained at least one CpG dinucleotide, occurred

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采用固相萃取-气相色谱-质谱法(GC-MS)测定污水中辛酚(OP)、壬酚(NP)、双酚A(BPA)、己烯雌酚(DES)、雌酮(E1)、17β-雌二醇(E2)、17α-乙炔雌二醇(EE2)和雌三醇(E3)8种具有雌激素活性的化合物。被测组分的加标回收率为(65.4±4.0)%~(110.0±4.5)%,检出限为1.0~7.5ng/L(相对标准偏差为5.2%~15.6%)。经检测,武汉某城市污水处理厂进水中的目标化合物(除EE2外)浓度为6.5~8954.9ng/L;除EE2和E3外,出水中的浓度为3.2~2

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利用14C标记1,2,7,8-四氯代二苯并二噁英(1,2,7,8Tetrachloro[U—14C]dibenzodioxin,14C1,2,7,8TCDD)初步研究了其在鲤体内的分布和代谢规律。14C1,2,7,8-TCDD溶解于丙酮/植物油中,腹腔暴露。暴露1、2、4、8、12d后取样,肝脏、胆汁、腹腔脂肪等消化制样后用液闪仪测量放射性活度。肝脏和胆汁内的放射性活度同步变化,都是第8d达到峰值后下降。腹腔脂肪内1—2d放射性明显高于随后取样的样品。肝和腹腔脂肪的分布量之比呈现“S”型变化趋势。暴露4d

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通过测定原代培养鲫鱼(Carassius auratus)肝细胞中雌激素受体所介导的卵黄蛋白原(Vtg)生成以及芳香烃受体所介导的CYP1A1基因转录水平的变化, 建立了一种类雌激素体外实验模型. 实验结果表明, Vtg和Vtg mRNA的表达与己烯雌酚(DES)之间均有很好的剂量-效应关系, Vtg和Vtg mRNA均可作为指示类雌激素毒性的生物标志物. TCDD, B[a]P可显著抑制鱼肝细胞中DES诱导的Vtg和Vtg mRNA的表达, 呈明显的抗雌激素效应, 并同时激活了CYP1A1 基因的表达;