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Simultaneous quantification of leukotrienes and hydroxyeicosatetraenoic acids in cell culture medium using liquid chromatography/tandem mass spectrometry 下载免费PDF全文
Leukotrienes (LTs) and hydroxyeicosatetraenoic acids (HETEs) are important bioactive lipid mediators that participate in various pathophysiological processes. To advance understanding of the mechanisms that regulate these mediators in physiological and pathological processes, an analytical method using liquid chromatography/tandem mass spectrometry for the simultaneous quantification of LTB4, LTC4, LTD4, LTE4, 5‐HETE, 8‐HETE, 12‐HETE and 15‐HETE in cell culture media was developed. A Supel?‐Select HLB solid‐phase extraction cartridge was used for sample preparation. The compounds were separated on a C18 column using gradient elution with acetonitrile–water–formic acid (20:80:0.1, v/v/v) and acetonitrile–formic acid (100:0.1, v/v). The calibration curves of LTB4, LTD4, LTE4 and HETEs were linear in the range of 0.025–10 ng/mL, and the calibration curve of LTC4 was linear in the range of 0.25–10 ng/mL. Validation assessment showed that the method was highly reliable with good accuracy and precision. The stability of LTs and HETEs was also investigated. Using the developed method, we measured LTs and HETEs in the culture supernatant of the human mast cell line HMC‐1. The present method could facilitate investigations of the mechanisms that regulate the production, release and signaling of LTs and HETEs. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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Membrane transporters are expressed in various bodily tissues and play essential roles in the homeostasis of endogenous substances and the absortion, distribution and/or excretion of xenobiotics. For transporter assays, radioisotope‐labeled compounds have been mainly used. However, commercially available radioisotope‐labeled compounds are limited in number and relatively expensive. Chromatographic analyses such as high‐performance liquid chromatography with ultraviolet absorptiometry and liquid chromatography with tandem mass spectrometry have also been applied for transport assays. To elucidate the transport properties of endogenous substrates, although there is no difficulty in performing assays using radioisotope‐labeled probes, the endogenous background and the metabolism of the compound after its translocation across cell membranes must be considered when the intact compound is assayed. In this review, the current state of knowledge about the transport of endogenous substrates via membrane transporters as determined by chromatographic techniques is summarized. Chromatographic techniques have contributed to our understanding of the transport of endogenous substances including amino acids, catecholamines, bile acids, prostanoids and uremic toxins via membrane transporters. 相似文献
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曝光系统离焦对平面全息光栅衍射波前的影响 总被引:1,自引:0,他引:1
波前像差是衍射光栅的重要技术指标,它直接影响光栅的分辨率。由光致刻蚀剂记录两束相干光干涉条纹是制作全息光栅的关键步骤。为了提高全息光栅曝光系统调整精度、减小离焦、降低光栅的衍射波前像差,从离焦对反射球面准直镜的准直光平行度的影响程度出发,分析了准直光平行度对全息光栅衍射波前像差的影响。理论分析和数值模拟结果表明,准直镜调整误差直接决定全息光栅衍射波前像差大小。以3种不同刻线密度光栅为例,得出了准直镜调整误差的允许变化范围。 相似文献
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The utility of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) coupled with a peptide ladder sequencing method employing exopeptidase degradation for the analysis of phosphorylation site in a mono-phosphorylated peptide is investigated. MALDI-TOFMS analysis of time-dependent exopeptidase digestion using carboxypeptidase W and aminopeptidase M of the mono-phosphorylated 33-48 fragment isolated from a beta-casein tryptic digestion mixture allowed for the sequencing analysis from both the C-terminus and N-terminus. Negative ion detection MALDI-TOFMS made it possible to clearly measure the peptide ladder of mono-phosphorylated peptide by the strong negative charge localized at the phosphoric acid group. Since exopeptidase activity was suppressed by the existence of a phosphorylated amino acid residue, the termination exopeptidase degradation therefore suggested the existence of a phosphorylated amino acid residue at that site. This peptide ladder sequencing method using exopeptidases was effective for the identification of the site of a phosphorylated amino acid residue by a simple MALDI-TOFMS analysis in the negative ion detection mode. 相似文献
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对英文材料的双面规则碎片文件复原问题进行了研究.由于碎片边界是规则的几何形状,无法采用几何形状匹配算法进行复原,为此提出了基于碎片边缘像素特征的匹配复原算法,建立了双面二维灰度匹配数学模型.通过加入行约束条件,减少横向匹配中的纵向误差,并通过消除列匹配中的误差,优化了匹配算法.该模型可以实现块状双面英文碎片的完整复原. 相似文献
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以α-溴代丙酸乙酯为引发剂,CuCl/二乙烯三胺为催化剂,采用ATRP法制得5个不同分子量的聚甲基丙烯酸甲酯-聚甲基丙烯酸二甲氨乙酯嵌段共聚物(PMMA-b-PDMAEMA, P1~P5); P1~P5经溴代辛烷季铵化合成了5个聚季铵盐(Q1~Q5),其结构和性能经1H NMR, FT-IR, GPC和DSC表征。结果表明:P4和Q4的玻璃化转变温度分别为109.67 ℃和117.95 ℃。采用平板活菌计数法研究了Q1~Q5对金黄色葡萄球菌(S. aureus)和大肠杆菌(E. coli)的抗菌活性。结果表明:Q1~Q5对S. aureus的抗菌活性优于E. coli,其MIC值分别为300 mg·L-1, 250 mg·L-1, 275 mg·L-1, 225 mg·L-1和150 mg·L-1。 相似文献
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通过热重-差热分析(TG-DTA),考察了Mn12-Ac磁性分子晶体从室温到270℃的热失重过程.结合x射线粉末衍射分析,认为在第一个失重阶段,即25—110℃,Mn12-Ac失去了处于团簇分子间隙的结晶乙酸和结晶水,同时失去了团簇分子中与4个Mn3+配位的4个H2O,Mn12-Ac单晶结构被破坏,但是团簇分子的基本结构依然存在;在第二个失重阶段,即180—230℃,Mn12-Ac转变为γ-Mn2O3,其中混有少量Mn3O4.
关键词:
Mn12
分子团簇
热重-差热分析
x射线衍射 相似文献