通讯机构：
[He, Shuya] U;Univ S China, Dept Biochem & Mol Biol, Hengyang 421001, Peoples R China.
关键词：
small interfering RNA;hypoxia-inducible factor-1 alpha;multidrug resistance-1;multidrug resistance-associated protein
摘要：
This study aimed to investigate the effects of knocking down hypoxia-inducible factor-1α (HIF-1α) through RNA interference on hypoxia-induced increases in drug resistance in A549/CDDP cells, and to study the underlying mechanisms. A small interfering RNA (siRNA) eukaryotic expression vector targeting HIF-1α was constructed and transfected into A549/CDDP cells treated with hypoxia. The mRNA and protein levels of HIF-1α, multidrug resistance-1 (MDR1), and multidrug resistance-associated protein (MRP) were determined by reverse transcription polymerase chain reaction (RT-PCR) and immunocytochemistry. Cell viability following treatment with cisplatin was determined by MTT assay. Hypoxia increased the resistance of A549/CDDP cells to cisplatin and this effect was reversed by the siRNA inhibition of HIF-1α expression. Expression of HIF-1α siRNA also downregulated HIF-1α, MDR1 and MRP mRNA, and protein expression in A549/CDDP cells treated with hypoxia (p<0.05). Hypoxia-induced resistance of A549/CDDP cells to cisplatin is reversed by the siRNA inhibition of HIF-1α expression. This effect may be mediated by a decreased expression of MDR1 and MRP.
作者机构：
[Wang, Hong-Qing; He, Fang-Fang; Wang, Xiao-Feng] School of Chemistry and Chemical Engneering, University of South China, Hengyang 421001, China;[Zhou, Wei-Ping] College of Mathematics and Physical, University of South China, Hunan 421001, China;[Liu, Zhao-Jie] Institute of Organic Synthesis, Central China Normal University, Wuhan 430079, China
通讯机构：
[Wang, H.-Q.] S;School of Chemistry and Chemical Engneering, University of South China, China
摘要：
In the title compound, C30H23ClN6OS, the benzyl, the 3-chloroanilino, the phenyl and the anilino groups form dihedral angles of 85.95 (6), 29.63 (7), 28.55 (1) and 87.48 (6)°, respectively, with the pyrazolo[3,4-d]pyrimidine unit [maximum deviation = 0.052 (2) A]. An intramolecular N - H···N hydrogen bond occurs. The crystal structure features N - H···O hydrogen bonds.
作者机构：
[Li, Jie; Huang, Chunlin] Univ S China, Sch Pharm & Life Sci, Dept Biochem & Mol Biol, Hengyang 421001, Peoples R China.;[Guo, Bin; Wang, Xiaoying; Zhu, Weitao; Chen, Bo; Yao, Shouzhuo] Hunan Normal Univ, Minist Educ China, Key Lab Chem Biol & Tradit Chinese Med Res, Changsha 410081, Hunan, Peoples R China.;[Ouyang, Shan] Shenzhen Entry Exit Inspect & Quarantine Bur Peop, Food Inspect & Quarantine Ctr, Shenzhen 518067, Peoples R China.
通讯机构：
[Guo, Bin] H;Hunan Normal Univ, Minist Educ China, Key Lab Chem Biol & Tradit Chinese Med Res, Changsha 410081, Hunan, Peoples R China.
关键词：
Animal tissues;Dispersive solid-phase extraction;Multi-residue;Semi-targeted screening;Sulfonamides;Triple-quadrupole linear ion trap mass spectrometer
摘要：
A generic and efficient homolog-targeted approach was used to expand screening and detection of target class of sulfonamides and structural analogs, based on a fast single-tube extraction/partitioning-multifunction adsorption cleanup (SEP/MAC) for class-specific fragmentation-dependent acquisition with a liquid chromatography-hybrid triple-quadrupole linear ion trap mass spectrometer (LC-QqLIT). By combining the two-stage process conducted in a single tube as one-pot protocol, the straightforward SEP/MAC procedure was optimized to offer clean extracts with reasonable recovery (71-109% with RSDs < 20%) and decreased matrix interferences (-9 to 19%) of multiresidual sulfonamide extraction from different tissue samples. The novel use of neutral loss scan of 66 Da (NLS) or precursor ion scanning of m/z 108 (PreS) in positive ion mode was found to achieve more comprehensive coverage of protonated molecular ions of a wide array of sulfonamides including N-4-acetyl and hydroxylamine metabolites plus their possible dimers. Moreover, the PreS-triggered automatically enhanced product ion spectral acquisition enabled simultaneous screening, profiling and confirmation of an unlimited number of analytes belonging to the sulfonamide class within a single analysis. The validation and application results of the generic SEP/MAC-based LC-QqLIT strategy consistently demonstrated favorable performances with acceptable accuracy (67-116%), precision (RSDs < 25%), and sensitivity (LOQs <= 7.5 ng g(-1)) to meet the acceptance criteria for all the sulfonamide-tissue combinations. Thus, the integration of the matrix-independent SEP/MAC procedure and the multiparameter matching algorithm with the unit-resolution LC-QqLIT instrument can serve as a valuable semi-targeted discovery strategy for rapid screening and reliable quantitative/confirmatory analysis of real samples. (C) 2012 Elsevier B.V. All rights reserved.
摘要：
Bovine liver cytochrome b
5 (cyt b
5), with heme bound noncovalently, has been converted into a cyt c-like protein (cyt b
5 N57C) by constructing a thioether linkage between the heme and the engineered cysteine residue. With no X-ray or NMR structure available, we herein performed a molecular modeling study of cyt b
5 N57C. On the other hand, using amino acid sequence information for a newly discovered member of the cyt b
5 family, domestic silkworm cyt b
5 (DS cyt b
5), we predicted the protein structure by homology modeling in combination with MD simulation. The modeling structure shows that both Cys57 in cyt b
5 N57C, and Cys56, a naturally occurring cysteine in DS cyt b
5, have suitable orientations to form a thioether bond with the heme 4-vinyl group, as the heme is in orientation A. In addition to providing structural information that was not previously obtained experimentally, these modeling studies provide insight into the formation of cyt c-like thioether linkages in cytochromes, and suggest that c-type cyt b
5 maturation involves a b-type intermediate.
摘要：
A novel method for determination of trace amounts of microorganism populations in solution was developed by using a multiwalled carbon nanotube (MWNT) modified glassy carbon electrode and square wave voltammetry (SWV). The simultaneous combination of MWNT and SWV allowed the electrochemical signal of electro-active materials in Escherichia coli O157:H7 (E. coli) to be dramatically amplified. Compared with a bare glassy carbon electrode, the MWNT-modified glassy carbon electrode showed catalytic properties in the oxidation of electro-active materials on cell surfaces. Moreover, SWV was proved to be more sensitive than cyclic voltammetry (CV) for investigation of the electrochemical behavior of cells. In this paper, a linear relationship was obtained between the SWV peak current and the cell concentration in the range 2 × 102–2 × 108 cell mL−1 with a detection limit of 2 × 102 cell mL−1. The effect of antibiotic drug Gentamycin Sulfate injection (GSI) on the growth of E. coli was also investigated.
