Name: simultaneous quantification of selected kynurenines analyzed by liquid chromatography-mass spectrometry in medium collected from cancer cell cultures
Uploaded: 2020-05-09T13:30:00
Description: Watch this Scientific Journal Video about Simultaneous Quantification of Selected Kynurenines Analyzed by Liquid Chromatography-Mass Spectrometry in Medium Collected from Cancer Cell Cultures at JoVE.

这项工作得到欧洲联盟根据《2007-2013年波兰东部业务方案发展》获得欧洲联盟区域发展基金的支持（POPW.01.03.00-06-003/09-00），由卢布林约翰·保罗二世天主教大学生物技术和环境科学学院（波兰国家科学中心为伊洛娜·萨多克提供青年科学家赠款）， OPUS13 （2017/25/B/NZ4/01198 马格达莱娜·斯塔尼谢夫斯卡，原则调查员）。 作者感谢JPY CUL跨学科研究中心氧化应激实验室的阿格涅什卡·奇比尔教授分享细胞培养和蛋白质定量设备。

1. 准备标准 3NT、Kyn、3HKyn、3HAA、XA 标准库存解决方案
<ol><li>以最高精度（每瓶0.3毫克）在小瓶中称量试剂。为了提高准确性，请放大试剂，根据步骤 1.2 调整溶剂的体积。</li>
	<li>溶解溶剂在溶剂的300μL，以获得1克/升的库存溶液。溶解3NT在1%（v/v）的微酸（FA）在水中;金，3HAA和XA在二甲基硫化物（DMSO）;3HKyn 在水中酸化到 pH 2.5 与盐酸 （HCL）. 警告：3HAA刺激眼睛、鼻子、喉咙和肺部。吸入、接...

<ol>
	<li>Li, F., Zhang, R., Li, S., Liu, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=IDO1:+an+import+ant+immunotherapy+target+in+cancer+treatment.">IDO1: an import ant immunotherapy target in cancer treatment.</a> International Immunopharmacology. 47, 70-77 (2017).</li><li>Heng, B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Understanding+the+role+of+the+kynurenine+pathway+in+human+breast+cancer+immunobiology.">Understanding the role of the kynurenine pathway in human breast cancer immunobiology.</a> Oncotarget. 7 (6), 6506-6520 (2015).</li><li>Badawy, A. A. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Kynurenine+pathway+and+human+systems.">Kynurenine pathway and human systems.</a> Experimental Gerontology. 129, (2020).</li><li>Chen, Y., Guillemin, G. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Kynurenine+pathway+metabolites+in+humans:+Disease+and+healthy+states.">Kynurenine pathway metabolites in humans: Disease and healthy states.</a> International Journal of Tryptophan Research. 2 (1), 1-19 (2009).</li><li>Sathyasaikumar, K. V., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Xanthurenic+Acid+Formation+from+3-Hydroxykynurenine+in+the+Mammalian+Brain:+Neurochemical+Characterization+and+Physiological+Effects.">Xanthurenic Acid Formation from 3-Hydroxykynurenine in the Mammalian Brain: Neurochemical Characterization and Physiological Effects.</a> Neuroscience. 367, 85-97 (2017).</li><li>Malina, H., Richter, C., Frueh, B., Hess, O. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lens+epithelial+cell+apoptosis+and+intracellular+Ca2++increasein+the+presence+of+xanthurenic+acid.">Lens epithelial cell apoptosis and intracellular Ca2+ increasein the presence of xanthurenic acid.</a> BMC Ophthalmology. 2, 1-7 (2002).</li><li>Col&#237;n-Gonz&#225;lez, A. L., Maldonado, P. D., Santamar&#237;a, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=3-Hydroxykynurenine:+an+intriguing+molecule+exerting+dual+actions+in+the+central+nervous+system.">3-Hydroxykynurenine: an intriguing molecule exerting dual actions in the central nervous system.</a> Neurotoxicology. 34, 189-204 (2013).</li><li>Xue, P., Fu, J., Zhou, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+aryl+hydrocarbon+receptor+and+tumor+immunity.">The aryl hydrocarbon receptor and tumor immunity.</a> Frontiers in Immunology. 9 (286), 00286 (2018).</li><li>Tan, V. X., Guillemin, G. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Kynurenine+pathway+metabolites+as+biomarkers+for+amyotrophic+lateral+sclerosis.">Kynurenine pathway metabolites as biomarkers for amyotrophic lateral sclerosis.</a> Frontiers in Microbiology. 13 (1013), 1-11 (2019).</li><li>Wilding, J. L., Bodmer, W. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cancer+cell+lines+for+drug+discovery+and+development.">Cancer cell lines for drug discovery and development.</a> Cancer Research. 14 (40), 2377-2384 (2015).</li><li>Takikawa, O., Kuroiwa, T., Yamazaki, F., Kido, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanism+of+interferon-gamma+action.+Characterization+of+indoleamine+2,3-dioxygenase+in+cultured+human+cells+induced+by+interferon-gamma+and+evaluation+of+the+enzyme-mediated+tryptophan+degradation+in+its+anticellular+activity.">Mechanism of interferon-gamma action. Characterization of indoleamine 2,3-dioxygenase in cultured human cells induced by interferon-gamma and evaluation of the enzyme-mediated tryptophan degradation in its anticellular activity.</a> Journal of Biological Chemistry. 263 (4), 2041-2048 (1988).</li><li>Park, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Indoleamine-2,3-dioxygenase+in+thyroid+cancer+cells+suppresses+natural+killer+cell+function+by+inhibiting+NKG2D+and+NKp46+expression+via+STAT+signaling+pathways.">Indoleamine-2,3-dioxygenase in thyroid cancer cells suppresses natural killer cell function by inhibiting NKG2D and NKp46 expression via STAT signaling pathways.</a> Journal of Clinical Medicine. 8 (6), 842-859 (2019).</li><li>Sadok, I., Gamian, A., Staniszewska, M. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chromatographic+analysis+of+tryptophan+metabolites.">Chromatographic analysis of tryptophan metabolites.</a> Journal of Separation Science. 40 (15), 3020-3045 (2017).</li><li>Fuertig, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=LC-MS/MS-based+quantification+of+kynurenine+metabolites,+tryptophan,+monoamines+and+neopterin+in+plasma,+cerebrospinal+fluid+and+brain.">LC-MS/MS-based quantification of kynurenine metabolites, tryptophan, monoamines and neopterin in plasma, cerebrospinal fluid and brain.</a> Bioanalysis. 8 (18), 1903-1917 (2016).</li><li>Marcos, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Targeting+tryptophan+and+tyrosine+metabolism+by+liquid+chromatography+tandem+mass+spectrometry.">Targeting tryptophan and tyrosine metabolism by liquid chromatography tandem mass spectrometry.</a> Journal of Chromatography A. 1434, 91-101 (2016).</li><li>M&#246;ller, M., Du Preez, J., Harvey, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+and+validation+of+a+single+analytical+method+for+the+determination+of+tryptophan,+and+its+kynurenine+metabolites+in+rat+plasma.">Development and validation of a single analytical method for the determination of tryptophan, and its kynurenine metabolites in rat plasma.</a> Journal of Chromatography B: Analytical Technologies in Biomedical Life Science. 898, 121-129 (2012).</li><li>Lesniak, W. G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Concurrent+quantification+of+tryptophan+and+its+major+metabolites.">Concurrent quantification of tryptophan and its major metabolites.</a> Analytical Biochemistry. 443 (2), 222-231 (2013).</li><li>Badawy, A. A. B., Morgan, C. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rapid+isocratic+liquid+chromatographic+separation+and+quantification+of+tryptophan+and+six+kynurenine+metabolites+in+biological+samples+with+ultraviolet+and+fluorimetric+detection.">Rapid isocratic liquid chromatographic separation and quantification of tryptophan and six kynurenine metabolites in biological samples with ultraviolet and fluorimetric detection.</a> International Journal of Tryptophan Research. 3, 175-186 (2010).</li><li>Vignau, J., Jacquemont, M. C., Lefort, A., Imbenotte, M., Lhermitte, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Simultaneous+determination+of+tryptophan+and+kynurenine+in+serum+by+HPLC+with+UV+and+fluorescence+detection.">Simultaneous determination of tryptophan and kynurenine in serum by HPLC with UV and fluorescence detection.</a> Biomedical Chromatography. 18 (10), 872-874 (2004).</li><li>Zhang, A., Rijal, K., Ng, S. K., Ravid, K., Chitalia, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+mass+spectrometric+method+for+quantification+of+tryptophan-derived+uremic+solutes+in+human+serum.">A mass spectrometric method for quantification of tryptophan-derived uremic solutes in human serum.</a> Journal of Biological Methods. 4 (3), 75 (2017).</li><li>Arnhard, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+validated+liquid+chromatography-high+resolution-tandem+mass+spectrometry+method+for+the+simultaneous+quantitation+of+tryptophan,+kynurenine,+kynurenic+acid,+and+quinolinic+acid+in+human+plasma.">A validated liquid chromatography-high resolution-tandem mass spectrometry method for the simultaneous quantitation of tryptophan, kynurenine, kynurenic acid, and quinolinic acid in human plasma.</a> Electrophoresis. 39 (9-10), 1171-1180 (2018).</li><li>Oh, J. S., Seo, H. S., Kim, K. H., Pyo, H., Chung, B. C., Lee, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Urinary+profiling+of+tryptophan+and+its+related+metabolites+in+patients+with+metabolic+syndrome+by+liquid+chromatography-electrospray+ionization/mass+spectrometry.">Urinary profiling of tryptophan and its related metabolites in patients with metabolic syndrome by liquid chromatography-electrospray ionization/mass spectrometry.</a> Analytical and Bioanalytical Chemistry. 409 (23), 5501-5512 (2017).</li><li>Huang, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+simple+LC-MS/MS+method+for+determination+of+kynurenine+and+tryptophan+concentrations+in+human+plasma+from+HIV-infected+patients.">A simple LC-MS/MS method for determination of kynurenine and tryptophan concentrations in human plasma from HIV-infected patients.</a> Bioanalysis. 5 (11), 1397-1407 (2013).</li><li>Yamada, K., Miyazzaki, T., Shibata, T., Hara, N., Tsuchiya, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Simultaneous+measurement+of+tryptophan+and+related+compounds+by+liquid+chromatography/electrospray+ionization+tandem+mass+spectrometry.">Simultaneous measurement of tryptophan and related compounds by liquid chromatography/electrospray ionization tandem mass spectrometry.</a> Journal of Chromatography B: Analytical Technologies in Biomedical and Life Sciences. 867 (1), 57-61 (2008).</li><li>Zhu, W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantitative+profiling+of+tryptophan+metabolites+in+serum,+urine,+and+cell+culture+supernatants+by+liquid+chromatography-tandem+mass+spectrometry.">Quantitative profiling of tryptophan metabolites in serum, urine, and cell culture supernatants by liquid chromatography-tandem mass spectrometry.</a> Analytical and Bioanalytical Chemistry. 401, 3249-3261 (2011).</li><li>Hashioka, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Metabolomics+analysis+implies+noninvolvement+of+the+kynurenine+pathway+neurotoxins+in+the+interferon-gamma-+induced+neurotoxicity+of+adult+human+astrocytes.">Metabolomics analysis implies noninvolvement of the kynurenine pathway neurotoxins in the interferon-gamma- induced neurotoxicity of adult human astrocytes.</a> Neuropsychiatry. 7 (2), (2017).</li><li>Sadok, I., Rachwa&#322;, K., Staniszewska, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Application+of+the+optimized+and+validated+LC-MS+method+for+simultaneous+quantification+of+tryptophan+metabolites+in+culture+medium+from+cancer+cells.">Application of the optimized and validated LC-MS method for simultaneous quantification of tryptophan metabolites in culture medium from cancer cells.</a> Journal of Pharmaceutical and Biomedical Analysis. 176, 112805-112815 (2019).</li><li>Annesley, T. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ion+suppression+in+mass+spectrometry.">Ion suppression in mass spectrometry.</a> Clinical Chemistry. 49 (7), 1041-1044 (2003).</li><li>Hou&#233;e-L&#233;vin, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Exploring+oxidative+modifications+of+tyrosine:+An+update+on+mechanisms+of+formation,+advances+in+analysis+and+biological+consequences.">Exploring oxidative modifications of tyrosine: An update on mechanisms of formation, advances in analysis and biological consequences.</a> Free Radical Research. 49 (4), 347-373 (2015).</li><li>Wei, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Abnormal+Expression+of+Indoleamine+2,+3-Dioxygenase+in+Human+Recurrent+Miscarriage.">Abnormal Expression of Indoleamine 2, 3-Dioxygenase in Human Recurrent Miscarriage.</a> Reproductive Sciences. , (2019).</li><li>Liu, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Expression+of+indoleamine+2,3-dioxygenase+in+nasopharyngeal+carcinoma+impairs+the+cytolytic+function+of+peripheral+blood+lymphocytes.">Expression of indoleamine 2,3-dioxygenase in nasopharyngeal carcinoma impairs the cytolytic function of peripheral blood lymphocytes.</a> BMC Cancer. 9, 416 (2009).</li><li>Mailankot, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Indoleamine+2,3-dioxygenase+overexpression+causes+kynurenine-modification+of+proteins,+fiber+cell+apoptosis+and+cataract+formation+in+the+mouse+lens.">Indoleamine 2,3-dioxygenase overexpression causes kynurenine-modification of proteins, fiber cell apoptosis and cataract formation in the mouse lens.</a> Laboratory Investigation: A Journal of Technical Methods and Pathology. 89 (5), 498-512 (2009).</li></ol>

本文提出了一个详细的LC-SQ协议，用于同时量化四个主要的Trp代谢物（3HKyn，Kyn，3HAA，XA），这些代谢物是用 体外 培养的人类癌细胞的介质测量的。特别注意样品的准备、色谱/质谱过程和数据解释，这是分析中最重要的一点。
一般来说，LC-MS 分析由于灵敏度高，需要对二手材料的严格性和纯度进行最高标准的协议。它是指在整个标准程序中应用整齐清洁和正确洗涤的?...

基努琳通路 （KP） 是人类细胞中色氨酸 （Trp） 催化的主要途径。在肝外细胞中，印度胺-2，3-二氧酶（IDO-1）是第一种限制KP酶，并将Trp转化为N-形成基核素1。KP 内的进一步步骤会生成其他次要代谢物，即具有各种生物特性的基努他宁。Kynurenine （Kyn） 是第一个稳定的 Trp 催化物， 显示有毒性质和调节细胞事件后， 结合到阿丽尔碳氢化合物受体 （AhR）2.随后，Kyn被自发地或在酶介质过程中转化为几个分子，产生诸如3-羟基核素（3HKyn）、炭酸（AA）、3-羟基苯甲酸（3-HAA）、基努雷尼酸（Kyna）和Xanthurenic酸（XA）等代谢物。另一种下游代谢物，2-氨基-3-卡博基霉素酸-6-半醛（ACMS），经历非酶循环奎诺利尼酸（QA）或野餐酸（PA）1.最后，QA被进一步转化为烟酰胺-腺苷二核苷酸（NAD+）3，KP端点代谢物，是一个重要的酶共同因子。一些基努肾上腺素具有神经保护特性，如Kyna和PA，而其他，即3HAA和3HKyn，是有毒的4。由3HKyn形成的Xanthurenic酸具有抗氧化和血管电离特性5。XA在老化的镜片中积累，导致上皮细胞6的凋亡。KP在20世纪中叶被描述，当它参与各种疾病被证明时，它得到了更多的关注。这种代谢途径的增加和一些kynurenine的积累调节免疫反应，并与不同的病理条件，如抑郁症，精神分裂症，脑病，艾滋病毒，痴呆症，肌萎缩性侧索硬化症，疟疾，阿尔茨海默氏症，亨廷顿舞蹈症和癌症4，7。在肿瘤微环境和癌细胞2，8中观察到Trp新陈代谢的一些变化。此外，基努雷宁被认为是有希望的疾病标记9。在癌症研究中，体外细胞培养模型已建立并广泛应用于抗癌药物10的药前评价。Trp代谢物由细胞分泌到培养基中，可以测量以评估基努艾琳通路的状态。因此，需要开发适当的方法，以简单、灵活和可靠的协议，在各种生物标本中同时检测尽可能多的KP代谢物。
在本文中，我们描述了一个协议，用于同时确定四个基努艾琳通路代谢物：Kyn、3HKyn、3HAA和XA，由LC-SQ在从癌细胞中收集的培养基中。在现代分析方法中，液相色谱13、14、15、16优先于同时检测和量化单个色氨酸催化物，而使用Erlich试剂11、12进行生化非特异性检测。目前，人类标本中有许多用于基努他宁测定的方法，主要基于带有紫外线或荧光检测仪13、17、18、19的液相色谱。液相色谱与质谱探测器 （LC-MS） 似乎更适合此类分析，因为其灵敏度较高（检测范围较低）、选择性和可重复性。
Trp代谢物已经确定在人类血清，血浆和尿液13，20，21，22，23，但是，其他生物标本的方法，如细胞培养介质也是需要的。此前，LC-MS用于培养人类胶质瘤细胞、单核细胞、支气管细胞或用干扰素伽马（IFN-γ）治疗的星形细胞（IFN-γ）24、25、26后收集的介质中的Trp衍生化合物。目前，需要新的验证协议，可以评估不同培养基、细胞和癌症模型中使用的治疗方法中的几个代谢物。
开发方法的目的是量化（在一次分析运行内）四个主要的基努雷宁，可以指示KP的异常。这里介绍的是我们最近出版的协议的关键步骤，定量LC-SQ分析选定的有意义的基努雷宁使用一个内部标准（3-硝基罗辛，3NT）在从 体外 培养的人类癌细胞27收集的介质。据我们所知，这是第一个LC-SQ协议，用于在从 体外 生长细胞获得的培养基中同时量化3HKyn、3HAA、Kyn和XA。经过一些修改后，该方法可以进一步应用于研究Trp代谢在更广泛的细胞培养模型中的变化。

<table border="0" cellpadding="0" cellspacing="0" style="width:1360px;" width="1359">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:411px;">3-hydroksy-DL-kynurenina</td>
			<td style="width:175px;">Sigma-Aldrich</td>
			<td style="width:261px;">H1771</td>
			<td style="width:513px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">3-hydroxyanthranilic acid</td>
			<td style="width:175px;">Sigma-Aldrich</td>
			<td style="width:261px;">148776</td>
			<td>97%</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:411px;">3-nitro-L-tyrosine</td>
			<td style="width:175px;">Sigma-Aldrich</td>
			<td style="width:261px;">N7389</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:411px;">Acetonitrile</td>
			<td style="width:175px;">Supelco</td>
			<td>1.00029</td>
			<td>hypergrade for LC-MS LiChrosolv</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:411px;">Activated charcoal</td>
			<td style="width:175px;">Supelco</td>
			<td>05105</td>
			<td>powder</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:411px;">Analytical balance</td>
			<td style="width:175px;">Ohaus</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="29">
			<td height="29" style="height:29px;width:411px;">Analytical column</td>
			<td style="width:175px;">Agilent Technologies</td>
			<td>959764-902</td>
			<td>Zorbax Eclipse Plus C18 rapid resolution HT (2.1 x 100 mm, 1.8 &#181;m)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Ammonium formate</td>
			<td style="width:175px;">Supelco</td>
			<td style="width:261px;">7022</td>
			<td>eluent additive for LC-MS, LiChropur, &#8805;99.0%</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Bovine Serum Albumin</td>
			<td style="width:175px;">Sigma</td>
			<td>1001887398</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Caps for chromatographic vials</td>
			<td style="width:175px;">Agilent Technologies</td>
			<td>5185-5820</td>
			<td>blue screw caps,PTFE/red sil sepa</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Cell culture dish</td>
			<td style="width:175px;">Nest</td>
			<td>704004</td>
			<td>polystyrene, non-pyrogenic, sterile</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Cell culture plate</td>
			<td style="width:175px;">Biologix</td>
			<td>07-6012</td>
			<td>12-well, non-pyrogenic, non-cytoxic, sterille</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Cell incubator</td>
			<td>Thermo Fisher Scientific</td>
			<td></td>
			<td>HERAcell 150i Cu</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Centrifuge</td>
			<td style="width:175px;">Eppendorf</td>
			<td style="width:261px;"></td>
			<td>model 5415R</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Centrifuge</td>
			<td style="width:175px;">Eppendorf</td>
			<td style="width:261px;"></td>
			<td>model 5428</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Centrifuge tubes</td>
			<td style="width:175px;">Bionovo</td>
			<td>B-2278</td>
			<td>Eppendorf type, 1.5 mL</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Centrifuge tubes</td>
			<td style="width:175px;">Bionovo</td>
			<td>B-3693</td>
			<td>Falcon type, 50 mL, PP</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Chromatographic data acqusition and analysis software</td>
			<td style="width:175px;">Agilent Technologies</td>
			<td></td>
			<td>LC/MSD ChemStation (B.04.03-S92)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Chromatographic insert vials</td>
			<td style="width:175px;">Agilent Technologies</td>
			<td>9301-1387</td>
			<td>100 &#181;L</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Chromatographic vials</td>
			<td style="width:175px;">Agilent Technologies</td>
			<td>5182-0714</td>
			<td>2 mL, clear glass</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:411px;">Dimethyl sulfoxide</td>
			<td style="width:175px;">Supelco</td>
			<td style="width:261px;">1.02950</td>
			<td>Uvasol</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:411px;">Dubelcco&#8217;s Modified Eagle&#8217;s Medium (DMEM)</td>
			<td style="width:175px;">PAN Biotech</td>
			<td>P04-41450</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:411px;">Dual meter pH/conductivity</td>
			<td style="width:175px;">Mettler Toledo</td>
			<td style="width:261px;"></td>
			<td>SevenMulti</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Evaporator</td>
			<td style="width:175px;">Genevac</td>
			<td style="width:261px;"></td>
			<td>model EZ-2.3 Elite</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Fetal bovine serum</td>
			<td style="width:175px;">Sigma-Aldrich</td>
			<td>F9665</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:411px;">Formic acid</td>
			<td style="width:175px;">Supelco</td>
			<td style="width:261px;">5.33002</td>
			<td>for LC-MS LiChropur</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:411px;">Glass bottle for reagents storage</td>
			<td style="width:175px;">Bionovo</td>
			<td>S-2070</td>
			<td>50 mL, clear glass</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:411px;">Guard column</td>
			<td style="width:175px;">Agilent Technologies</td>
			<td style="width:261px;">959757-902</td>
			<td>Zorbax Eclipse Plus-C18 Narrow Bore Guard Column (2.1 x 12.5 mm, 5 &#181;m)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:411px;">Hydrochloric acid</td>
			<td style="width:175px;">Merck</td>
			<td>1.00317.1000</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:411px;">L-kynurenine</td>
			<td style="width:175px;">Sigma-Aldrich</td>
			<td style="width:261px;">K8625</td>
			<td>&#8805;98% (HPLC)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:411px;">Magnetic stirrer</td>
			<td style="width:175px;">Wigo</td>
			<td style="width:261px;"></td>
			<td>ES 21 H</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Microbalance</td>
			<td style="width:175px;">Mettler Toledo</td>
			<td></td>
			<td>model XP6</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:411px;">Milli-Q system</td>
			<td style="width:175px;">Millipore</td>
			<td>ZRQSVPO30</td>
			<td>Direct-Q 3 UV with Pump</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Quadrupole mass spectrometer</td>
			<td style="width:175px;">Agilent Technologies</td>
			<td>G1948B</td>
			<td>model 6120</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Penicillin-Streptomycin</td>
			<td style="width:175px;">Sigma-Adrich</td>
			<td>048M4874V</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Plate reader</td>
			<td style="width:175px;">Bio Tek</td>
			<td></td>
			<td>Synergy 2 operated by Gen5</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Potassium chloride</td>
			<td style="width:175px;">Merck</td>
			<td>1.04936.1000</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Potassium dihydrogen phosphate</td>
			<td style="width:175px;">Merck</td>
			<td>1.05108.0500</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Protein Assay Dye Reagent Concentrate</td>
			<td style="width:175px;">BioRad</td>
			<td>500-0006</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">See-saw rocker</td>
			<td style="width:175px;">Stuart</td>
			<td>SSL4</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Serological pipette</td>
			<td style="width:175px;">Nest</td>
			<td>326001</td>
			<td>5 mL, polystyrene, non-pyrogenic, sterile</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Sodium chloride</td>
			<td style="width:175px;">Sigma-Aldrich</td>
			<td style="width:261px;">7647-14-5</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Sodium phosphate dibasic</td>
			<td style="width:175px;">Merck</td>
			<td>1.06346.1000</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Solvent inlet filter</td>
			<td style="width:175px;">Agilent Technologies</td>
			<td>5041-2168</td>
			<td>glass filter, 20 &#956;m pore size</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Solvent reservoir (for LC-MS)</td>
			<td style="width:175px;">Agilent Technologies</td>
			<td>9301-6524</td>
			<td>1 L, clear glass</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Solvent reservoir (for LC-MS)</td>
			<td style="width:175px;">Agilent Technologies</td>
			<td>9301-6526</td>
			<td>1 L, amber glass</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Spreadsheet program</td>
			<td style="width:175px;">Microsoft Office</td>
			<td></td>
			<td>Microsoft Office Excel</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Stir bar</td>
			<td style="width:175px;">Bionovo</td>
			<td>6-2003</td>
			<td>teflon coated</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Syringe filters for culture medium filtration</td>
			<td style="width:175px;">Bionovo</td>
			<td>7-8803</td>
			<td>regenerated cellulose, &#216; 30 mm, 0,45 &#181;m</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Syringe filters for mobile phase components filtration</td>
			<td style="width:175px;">Bionovo</td>
			<td>6-0018</td>
			<td>nylon, &#216; 30 mm, 0,22 &#181;m</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Tissue culture plates</td>
			<td style="width:175px;">VWR</td>
			<td>10062-900</td>
			<td>96-wells, sterille</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Trypsin-EDTA Solution</td>
			<td style="width:175px;">Sigma-Aldrih</td>
			<td>T4049-100 mL</td>
			<td></td>
		</tr>
		<tr height="50">
			<td height="50" style="height:50px;width:411px;">Ultra-High Performance Liquid Chromatography system</td>
			<td style="width:175px;">Agilent Technologies</td>
			<td style="width:261px;">G1367D, G1379B, G1312B, G1316C</td>
			<td style="width:513px;">1200 Infinity system consisted of autosampler (G1367D), degasser (G1379B), binary pump (G1312B), column thermostat (G1316C)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Ultrasound bath</td>
			<td>Polsonic</td>
			<td>104533</td>
			<td>model 6D</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Vortex</td>
			<td>Biosan</td>
			<td></td>
			<td>model V-1 plus</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:411px;">Xanthurenic acid</td>
			<td style="width:175px;">Sigma-Aldrich</td>
			<td style="width:261px;">D120804</td>
			<td>96%</td>
		</tr>
	</tbody>
</table>

simultaneous quantification of selected kynurenines analyzed by liquid chromatography-mass spectrometry in medium collected from cancer cell cultures

基努雷宁通路和色氨酸卡塔博利特称为基努雷宁已经受到越来越多的关注，因为他们参与免疫调节和癌症生物学。 体外 细胞培养分析通常用于了解不同色氨酸卡托邦细胞在疾病机制中的贡献以及用于测试治疗策略。富含分泌代谢物和信号分子的细胞培养介质反映了色氨酸代谢和其他细胞事件的状态。需要在复杂的细胞培养介质中可靠量化多种基努他宁的新协议，以便对多个样本进行可靠和快速的分析。这可以通过液体色谱与质谱学相结合来完成。这种强大的技术用于许多临床和研究实验室的代谢物的定量，可用于测量基努他宁。
这里介绍的是使用液相色谱与单四足质谱（LC-SQ）同时确定四个基努他宁，即基努雷宁，3-羟基核素，3-羟基苯甲酸，和从 体外 培养癌细胞中收集的介质中的黄曲霉素酸。SQ探测器使用简单，与其他质谱仪相比更便宜。在 SQ-MS 分析中，根据样品的特定质量与电荷比（m/z）生成并分离多个离子，然后使用单离子监控 （SIM） 模式进行检测。
本文注重报告方法的优点，指出了一些薄弱环节。它侧重于LC-SQ分析的关键要素，包括样品准备以及色谱和质谱分析。还讨论了质量控制、方法校准条件和矩阵效应等问题。我们描述了一个简单的应用3硝基酪氨酸作为一个模拟标准的所有目标分析。经人类卵巢癌和乳腺癌细胞实验证实，建议的LC-SQ方法产生可靠的结果，并可进一步应用于其他 体外 细胞模型。

LC-MS在生物活性分子的量化方面具有无可争辩的优势，尽管复杂标本的某些成分会导致所谓的基质效应，并损害分析物的电位化。它导致离子抑制或离子增强，严重降低精度，并影响LC-MS的检测/量化极限，这被认为是该方法的"弱"点。在我们的协议中，离子是由正模式下的电喷雾电离子化（ESI）产生的，这也用于Trp代谢物测定13的其他研究。然而，与大气压力化学电化<sup class="xref...

Watch this Scientific Journal Video about Simultaneous Quantification of Selected Kynurenines Analyzed by Liquid Chromatography-Mass Spectrometry in Medium Collected from Cancer Cell Cultures at JoVE.

Simultaneous Quantification of Selected Kynurenines Analyzed by Liquid Chromatography-Mass Spectrometry in Medium Collected from Cancer Cell Cultures

这里描述的是一个协议，用于确定从液体色谱分析的癌细胞培养物中收集的介质中产生的四种不同的色氨酸代谢物（金黄素、3-羟基核素、Xanthurenic酸、3-羟基苯甲酸）。

从癌细胞培养物中收集的介质光谱分析的选定金核素的同步量化

The kynurenine pathway and the tryptophan catabolites called kynurenines have received increased attention for their involvement in immune regulation and ...

Kynurenines are associated with immune response regulation in several diseases, including cancer. Reliable and validated methods for identifying multiple kynurenines aid in the development of more effective therapies. Our protocol uses liquid chromatography coupled with mass spectrometry to identify the different tryptophan metabolites generated by the kynurenine pathway in medium collected from cancer cell cultures.Unexperienced users may have some difficulty during the sample preparation or data acquisition and interpretation steps. By following our protocol and recommendations, one can avoid mistakes and obtain reliable data. To prepare stock solutions of the reagents, weigh out 0.3 milligrams of each reagent in a vial to the highest accuracy and dissolve each reagent in 300 microliters of the appropriate solvent to obtain one gram per liter stock solutions of each reagent.To prepare charcoal-treated culture medium, weigh out 280 milligrams of activated charcoal in a conical tube and add five milliliters of the liquid medium prepared for culturing the cells of interest. Shake the tube with the medium and charcoal on a seesaw rocker for two hours at room temperature and 50 oscillations per minute. At the end of the incubation, sediment the charcoal by centrifugation and carefully collect the supernatant without disturbing the charcoal, then filter the medium using a 0.45 micrometer syringe filter.To prepare the calibration solution, spike the charcoal-treated culture medium with 0.75 microliters of 0.1 gram per liter 3NT solution and add 3-H kynurenine, 3-HAA kynurenine, and xanthurenic acid to at least six different concentrations to cover all of the calibration ranges to a final volume of 150 microliters per sample. After vortexing, add 150 microliters of minus 20 degrees Celsius cold methanol supplemented with 1%formic acid to each tube for sample deproteinization and tightly cap and vortex the tubes again. After a 40-minute incubation at minus 20 degrees Celsius, centrifuge the samples and use an automatic pipette to transfer 270 microliters of each supernatant into individual flat bottom glass vials.Place the vials into an evaporator and use the appropriate program for water methanol fractions to gently evaporate the volatile components for about 30 minutes. When the tubes are dry, reconstitute each sample in 60 microliters of 0.1%formic acid in water and vortex the samples before transferring each solution into individual 1.5 milliliter tubes for centrifugation. Without disturbing the sediment, transfer the supernatants into chromatographic vials with conical glass inserts and place the vials into an LC-MS auto-sampler.Before running the samples, purge the LC system with the mobile phase to remove bubbles and to prime all of the solvent channels. Next, flush the guard and analytical column with 100%acetonitrile for about 30 minutes before flushing the system with 100%solvent A until a stable pressure is observed in the column, then set the appropriate LC parameters in the data acquisition software and construct a work list for running the samples on the LC system. To construct the calibration curve, in the data acquisition software, add the calibration standards into the work list and run the standards in triplicates, then integrate and measure the peak area corresponding to 3-hydroxykynurenine, kynurenine, 3-hydroxyanthranilic acid, 3-nitrotyrosine, and xanthurenic acid at the retention time of about 4.4, 10, 16, 21, and 30 minutes respectively.To collect supernatant samples from an in vitro cell culture, after 48 hours of standard cell culture of the cells of interest, transfer 500 microliters of supernatant from each well into individual 1.5 milliliter tubes and remove the cell debris by centrifugation, then transfer the medium supernatants into new tubes for minus 80 degrees Celsius storage until the analysis and maintain the cell pellets at minus 20 degrees Celsius until protein estimation analysis. To prepare samples for LC-MS analysis, transfer 149.25 microliters of each thawed culture medium sample into a new 1.5 microliter tube and add 0.75 microliters of 0.1 gram per liter 3NT solution to each tube. After preparing the samples as demonstrated, add 150 microliters of minus 20 degrees Celsius methanol supplemented with 1%formic acid to each tube and prepare the sample for LC-MS analysis as demonstrated.When the work list is complete, measure the peak area of each analyte and use an individual linear calibration equation dedicated for each analyte to calculate concentrations of the analytes present within each experimental sample. To assess cellular protein content corresponding to the sample of culture medium, resuspend each cell pellet in 100 microliters of PBS and freeze the samples at minus 20 degrees Celsius for one hour before thawing them on ice. After freeze-thawing the samples three times, collect the cell lysates by centrifugation and transfer the supernatants into new tubes without disturbing the pellets.Dilute the sample 10 times with fresh PBS and add the appropriate volumes of bovine serum albumin standard solution in duplicate to the appropriate wells of a 96-well plate. Load 10 to 15 microliters of each cell lysate sample supernatant to the appropriate wells of the 96-well plate and fill both the standard and sample wells to a final volume of 50 microliters of PBS per well. Next, add 200 microliters of a Bradford reagent diluted five times with ultra pure water to each well and incubate the plate for at least five minutes at room temperature.At the end of the incubation, load the plate onto a microplate reader and measure the absorbance at 595 nanometers, then construct a calibration curve to allow calculation of the amount of protein in each sample and divide the concentration of each kynurenine by the total protein content to normalize the kynurenine amount in each sample per one microgram of protein. Here are single quadrupole mass spectrometry results obtained during the analysis of medium containing 4.5 grams per liter of D-glucose and 10%fetal bovine serum. Note the small peak indicating the presence of kynurenine within the sample.Run a quality control sample before requiring the actual sample data to confirm the appropriate retention times of the analytes as a shift in LC signals or mismatches can be observed. Co-eluting matrix components can generate ions with the master charge ratio selected for the target analytes. For example, in this analysis, the peak from the unknown compound appeared in the scan period during which the ion of master charge ratio 206 was monitored.Due to the incompatibility of the retention time, the signal did not correspond to the analyte. Although the tryptophan isotope shared the same ion as master charge ratio 206, chromatographic analysis revealed that the tryptophan signal was well separated from the xanthurenic acid signal, indicating that the level of tryptophan present in the tested cancer cell medium did not impact xanthurenic acid quantification. This analysis of the culture medium from two types of cancer cell lines demonstrates that the evaluated human epithelial breast cancer cells released different amounts of tryptophan metabolites while the tested human ovarian cancer cells produced significantly higher levels of kynurenine.Using an internal standard during the sample preparation helps with reliable data acquisition. Normalization of the data to the protein content corrects for cell number variabilities within individual wells. Our protocol can be further expanded to determine additional analytes, but may accumulate in the culture medium under different experimental conditions.

simultaneous-quantification-selected-kynurenines-analyzed-liquid

Research

JoVE Journal

Bioengineering

Cellular Lipid Extraction for Targeted Stable Isotope Dilution Liquid Chromatography-Mass Spectrometry Analysis

The metabolism of fatty acids, such as arachidonic acid (AA) and linoleic acid (LA), results in the formation of oxidized bioactive lipids, including numerous stereoisomers1,2. These metabolites can be formed from free or esterified fatty acids. Many of these oxidized metabolites have biological activity and have been implicated in various diseases including cardiovascular and neurodegenerative diseases, asthma, and cancer3-7. Oxidized bioactive lipids can be formed enzymatically or by reactive oxygen species (ROS). Enzymes that metabolize fatty acids include cyclooxygenase (COX), lipoxygenase (LO), and cytochromes P450 (CYPs)1,8. Enzymatic metabolism results in enantioselective formation whereas ROS oxidation results in the racemic formation of products.
While this protocol focuses primarily on the analysis of AA- and some LA-derived bioactive metabolites; it could be easily applied to metabolites of other fatty acids. Bioactive lipids are extracted from cell lysate or media using liquid-liquid (l-l) extraction. At the beginning of the l-l extraction process, stable isotope internal standards are added to account for errors during sample preparation. Stable isotope dilution (SID) also accounts for any differences, such as ion suppression, that metabolites may experience during the mass spectrometry (MS) analysis9. After the extraction, derivatization with an electron capture (EC) reagent, pentafluorylbenzyl bromide (PFB) is employed to increase detection sensitivity10,11. Multiple reaction monitoring (MRM) is used to increase the selectivity of the MS analysis. Before MS analysis, lipids are separated using chiral normal phase high performance liquid chromatography (HPLC). The HPLC conditions are optimized to separate the enantiomers and various stereoisomers of the monitored lipids12. This specific LC-MS method monitors prostaglandins (PGs), isoprostanes (isoPs), hydroxyeicosatetraenoic acids (HETEs), hydroxyoctadecadienoic acids (HODEs), oxoeicosatetraenoic acids (oxoETEs) and oxooctadecadienoic acids (oxoODEs); however, the HPLC and MS parameters can be optimized to include any fatty acid metabolites13.
Most of the currently available bioanalytical methods do not take into account the separate quantification of enantiomers. This is extremely important when trying to deduce whether or not the metabolites were formed enzymatically or by ROS. Additionally, the ratios of the enantiomers may provide evidence for a specific enzymatic pathway of formation. The use of SID allows for accurate quantification of metabolites and accounts for any sample loss during preparation as well as the differences experienced during ionization. Using the PFB electron capture reagent increases the sensitivity of detection by two orders of magnitude over conventional APCI methods. Overall, this method, SID-LC-EC-atmospheric pressure chemical ionization APCI-MRM/MS, is one of the most sensitive, selective, and accurate methods of quantification for bioactive lipids.

This protocol will demonstrate the extraction and analysis of free and esterified bioactive fatty acids from cells. Fatty acids are accurately quantified using stable isotope dilution, chiral liquid chromatography, electron capture atmospheric chemical ionization multiple reaction monitoring mass spectrometry (SID-LC-ECAPCI-MRM/MS).

有针对性的稳定同位素稀释液相色谱 - 质谱法分析细胞脂质提取

The metabolism of fatty acids, such as arachidonic acid (AA) and linoleic acid (LA), results in the formation of oxidized bioactive lipids, including ...

科研

生物工程

Quantification of Global Diastolic Function by Kinematic Modeling-based Analysis of Transmitral Flow via the Parametrized Diastolic Filling Formalism

Quantitative cardiac function assessment remains a challenge for physiologists and clinicians.&#160;Although historically invasive methods have comprised the only means available, the development of noninvasive imaging modalities (echocardiography, MRI, CT) having high temporal and spatial resolution provide a new window for quantitative diastolic function assessment. Echocardiography is the agreed upon standard for diastolic function assessment, but indexes in current clinical use merely utilize selected features of chamber dimension (M-mode) or blood/tissue motion (Doppler) waveforms without incorporating the physiologic causal determinants of the motion itself.&#160;The recognition that all left ventricles (LV) initiate filling by serving as mechanical suction pumps allows global diastolic function to be assessed based on laws of motion that apply to all chambers. What differentiates one heart from another are the parameters of the equation of motion that governs filling. Accordingly, development of the Parametrized Diastolic Filling (PDF) formalism&#160;has shown that the entire range of clinically observed early transmitral flow (Doppler E-wave) patterns are extremely well fit by the laws of damped oscillatory motion.&#160;This permits analysis of individual E-waves in accordance with a causal mechanism (recoil-initiated suction) that yields three (numerically) unique lumped parameters whose physiologic analogues are chamber stiffness (k), viscoelasticity/relaxation (c), and load (xo).&#160;The recording of transmitral flow (Doppler E-waves) is standard practice in clinical cardiology and, therefore, the echocardiographic recording method is only briefly reviewed. Our focus is on determination of the PDF parameters from routinely recorded E-wave data.&#160;As the highlighted results indicate, once the PDF parameters have been obtained from a suitable number of load varying E-waves, the investigator is free to use the parameters or construct indexes from the parameters (such as stored energy 1/2kxo2, maximum A-V pressure gradient kxo, load independent index of diastolic function, etc.) and select the aspect of physiology or pathophysiology to be quantified.

Accurate, causality-based quantification of global diastolic function has been achieved by kinematic modeling-based analysis of transmitral flow via the Parametrized Diastolic Filling (PDF) formalism. PDF generates unique stiffness, relaxation,&#160;and load parameters and elucidates &#39;new&#39; physiology while providing sensitive and specific indexes of dysfunction.

全球舒张功能通过静脉流的通过参数化舒张形式主义运动学建模为基础的定量分析

Quantitative cardiac function assessment remains a challenge for physiologists and clinicians.&#160;Although historically invasive methods have comprised ...

Sample Preparation Strategies for Mass Spectrometry Imaging of 3D Cell Culture Models

Three dimensional cell cultures are attractive models for biological research. They combine the flexibility and cost-effectiveness of cell culture with some of the spatial and molecular complexity of tissue. For example, many cell lines form 3D structures given appropriate in vitro conditions. Colon cancer cell lines form 3D cell culture spheroids, in vitro mimics of avascular tumor nodules. While immunohistochemistry and other classical imaging methods are popular for monitoring the distribution of specific analytes, mass spectrometric imaging examines the distribution of classes of molecules in an unbiased fashion. While MALDI mass spectrometric imaging was originally developed to interrogate samples obtained from humans or animal models, this report describes the analysis of in vitro three dimensional cell cultures, including improvements in sample preparation strategies. Herein is described methods for growth, harvesting, sectioning, washing, and analysis of 3D cell cultures via matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS) imaging. Using colon carcinoma 3D cell cultures as a model system, this protocol demonstrates the ability to monitor analytes in an unbiased fashion across the 3D cell culture system with MALDI-MSI.

Immortalized cancer cell lines can be grown as 3D cell cultures, a valuable model for biological research. This protocol describes mass spectrometry imaging of 3D cell cultures, including improvements in the sample preparation platform. The goal of this protocol is to instruct users to prepare 3D cell cultures for mass spectrometry imaging analysis.

样品制备策略的3D细胞培养模型质谱成像

Three dimensional cell cultures are attractive models for biological research. They combine the flexibility and cost-effectiveness of cell culture with ...

Generation of Scalable, Metallic High-Aspect Ratio Nanocomposites in a Biological Liquid Medium

The goal of this protocol is to describe the synthesis of two novel biocomposites with high-aspect ratio structures. The biocomposites consist of copper and cystine, with either copper nanoparticles (CNPs) or copper sulfate contributing the metallic component. Synthesis is carried out in liquid under biological conditions (37 &#176;C) and the self-assembled composites form after 24 hr. Once formed, these composites are highly stable in both liquid media and in a dried form. The composites scale from the nano- to micro- range in length, and from a few microns to 25 nm in diameter. Field emission scanning electron microscopy with energy dispersive X-ray spectroscopy (EDX) demonstrated that sulfur was present in the NP-derived linear structures, while it was absent from the starting CNP material, thus confirming cystine as the source of sulfur in the final nanocomposites. During synthesis of these linear nano- and micro-composites, a diverse range of lengths of structures is formed in the synthesis vessel. Sonication of the liquid mixture after synthesis was demonstrated to assist in controlling average size of the structures by diminishing the average length with increased time of sonication. Since the formed structures are highly stable, do not agglomerate, and are formed in liquid phase, centrifugation may also be used to assist in concentrating and segregating formed composites.

Here we present a protocol to synthesize novel, high-aspect ratio biocomposites under biological conditions and in liquid media. The biocomposites scale from nanometers to micrometers in diameter and length, respectively. Copper nanoparticles (CNPs) and copper sulfate combined with cystine are the key components for the synthesis.

可扩展的，金属的高宽比纳米复合材料在生物液体中产生

The goal of this protocol is to describe the synthesis of two novel biocomposites with high-aspect ratio structures. The biocomposites consist of copper ...

Automated Robotic Liquid Handling Assembly of Modular DNA Devices

Recent advances in modular DNA assembly techniques have enabled synthetic biologists to test significantly more of the available &#34;design space&#34; represented by &#34;devices&#34; created as combinations of individual genetic components. However, manual assembly of such large numbers of devices is time-intensive, error-prone, and costly. The increasing sophistication and scale of synthetic biology research necessitates an efficient, reproducible way to accommodate large-scale, complex, and high throughput device construction.
Here, a DNA assembly protocol using the Type-IIS restriction endonuclease based Modular Cloning (MoClo) technique is automated on two liquid-handling robotic platforms. Automated liquid-handling robots require careful, often times tedious optimization of pipetting parameters for liquids of different viscosities (e.g. enzymes, DNA, water, buffers), as well as explicit programming to ensure correct aspiration and dispensing of DNA parts and reagents. This makes manual script writing for complex assemblies just as problematic as manual DNA assembly, and necessitates a software tool that can automate script generation. To this end, we have developed a web-based software tool, http://mocloassembly.com, for generating combinatorial DNA device libraries from basic DNA parts uploaded as Genbank files. We provide access to the tool, and an export file from our liquid handler software which includes optimized liquid classes, labware parameters, and deck layout. All DNA parts used are available through Addgene, and their digital maps can be accessed via the Boston University BDC ICE Registry. Together, these elements provide a foundation for other organizations to automate modular cloning experiments and similar protocols.
The automated DNA assembly workflow presented here enables the repeatable, automated, high-throughput production of DNA devices, and reduces the risk of human error arising from repetitive manual pipetting. Sequencing data show the automated DNA assembly reactions generated from this workflow are ~95% correct and require as little as 4% as much hands-on time, compared to manual reaction preparation.

Here, an automated workflow to perform modular DNA &#34;device&#34; assembly using a modular cloning DNA assembly method on liquid-handling robots is presented. The protocol uses an intuitive software tool for generating liquid handler picklists for combinatorial DNA device library generation, which we demonstrate using two liquid handling platforms.

模块化 DNA 设备的自动机器人液体处理组件

Recent advances in modular DNA assembly techniques have enabled synthetic biologists to test significantly more of the available &#34;design space&#34; ...

Synthesis of Biocompatible Liquid Crystal Elastomer Foams as Cell Scaffolds for 3D Spatial Cell Cultures

Here, we present a step-by-step preparation of a 3D, biodegradable, foam-like cell scaffold. These scaffolds were prepared by cross-linking star block co-polymers featuring cholesterol units as side-chain pendant groups, resulting in smectic-A (SmA) liquid crystal elastomers (LCEs). Foam-like scaffolds, prepared using metal templates, feature interconnected microchannels, making them suitable as 3D cell culture scaffolds. The combined properties of the regular structure of the metal foam and of the elastomer result in a 3D cell scaffold that promotes not only higher cell proliferation compared to conventional porous templated films, but also better management of mass transport (i.e., nutrients, gases, waste, etc.). The nature of the metal template allows for the easy manipulation of foam shapes (i.e., rolls or films) and for the preparation of scaffolds of different pore sizes for different cell studies while preserving the interconnected porous nature of the template. The etching process does not affect the chemistry of the elastomers, preserving their biocompatible and biodegradable nature. We show that these smectic LCEs, when grown for extensive time periods, enable the study of clinically relevant and complex tissue constructs while promoting the growth and proliferation of cells.

This study presents a methodology to prepare 3D, biodegradable, foam-like cell scaffolds based on biocompatible side-chain liquid crystal elastomers (LCEs). Confocal microscopy experiments show that foam-like LCEs allow for cell attachment, proliferation, and the spontaneous alignment of C2C12s myoblasts.

生物相容的液晶弹性体泡沫的合成中用作细胞支架的三维空间细胞培养

Here, we present a step-by-step preparation of a 3D, biodegradable, foam-like cell scaffold. These scaffolds were prepared by cross-linking star block ...

A Microcontroller Operated Device for the Generation of Liquid Extracts from Conventional Cigarette Smoke and Electronic Cigarette Aerosol

Electronic cigarettes are the most popular tobacco product among middle and high schoolers and are the most popular alternative tobacco product among adults. High quality, reproducible research on the consequences of electronic cigarette use is essential for understanding emerging public health concerns and crafting evidence based regulatory policy. While a growing number of papers discuss electronic cigarettes, there is little consistency in methods across groups and very little consensus on results. Here, we describe a programmable laboratory device that can be used to create extracts of conventional cigarette smoke and electronic cigarette aerosol. This protocol details instructions for the assembly and operation of said device, and demonstrates the use of the generated extract in two sample applications: an in vitro cell viability assay and gas-chromatography mass-spectrometry. This method provides a tool for making direct comparisons between conventional cigarettes and electronic cigarettes, and is an accessible entry point into electronic cigarette research.

Here, we describe a programmable laboratory device that can be used to create extracts of conventional cigarette smoke and electronic cigarette aerosol. This method provides a useful tool for making direct comparisons between conventional cigarettes and electronic cigarettes, and is an accessible entry point into electronic cigarette research.

一种单片机操作装置, 用于生成传统卷烟烟雾和电子烟气溶胶中的液体萃取物

Electronic cigarettes are the most popular tobacco product among middle and high schoolers and are the most popular alternative tobacco product among ...

Detection of Endotoxin in Nano-formulations Using Limulus Amoebocyte Lysate (LAL) Assays

When present in pharmaceutical products, a Gram-negative bacterial cell wall component endotoxin (often also called lipopolysaccharide) can cause inflammation, fever, hypo- or hypertension, and, in extreme cases, can lead to tissue and organ damage that may become fatal. The amounts of endotoxin in pharmaceutical products, therefore, are strictly regulated. Among the methods available for endotoxin detection and quantification, the Limulus Amoebocyte Lysate (LAL) assay is commonly used worldwide. While any pharmaceutical product can interfere with the LAL assay, nano-formulations represent a particular challenge due to their complexity. The purpose of this paper is to provide a practical guide to researchers inexperienced in estimating endotoxins in engineered nanomaterials and nanoparticle-formulated drugs. Herein, practical recommendations for performing three LAL formats including turbidity, chromogenic and gel-clot assays are discussed. These assays can be used to determine endotoxin contamination in nanotechnology-based drug products, vaccines, and adjuvants.

Detection of Endotoxin in Nano-formulations Using Limulus Amoebocyte Lysate LAL Assays

Detection of endotoxins in engineered nanomaterials represents one of the grand challenges in the field of nanomedicine. Here, we present a case study that describes the framework composed of three different LAL formats to estimate potential endotoxin contamination in nanoparticles.

用利穆鲁布莱巴细胞裂解液 (lal) 法检测纳米配方中的内毒素

When present in pharmaceutical products, a Gram-negative bacterial cell wall component endotoxin (often also called lipopolysaccharide) can cause ...

Establishing Single-Cell Based Co-Cultures in a Deterministic Manner with a Microfluidic Chip

Cell co-culture assays have been widely used for studying cell-cell interactions between different cell types to better understand the biology of diseases including cancer. However, it is challenging to clarify the complex mechanism of intercellular interactions in highly heterogeneous cell populations using conventional co-culture systems because the heterogeneity of the cell subpopulation is obscured by the average values; the conventional co-culture systems can only be used to describe the population signal, but are incapable of tracking individual cells behavior. Furthermore, conventional single-cell experimental methods have low efficiency in cell manipulation because of the Poisson distribution. Microfabricated devices are an emerging technology for single-cell studies because they can accurately manipulate single cells at high-throughput and can reduce sample and reagent consumption. Here, we describe the concept and application of a microfluidic chip for multiple single-cell co-cultures. The chip can efficiently capture multiple types of single cells in a culture chamber (~46%) and has a sufficient culture space useful to study the cells&#39; behavior (e.g., migration, proliferation, etc.) under cell-cell interaction at the single-cell level. Lymphatic endothelial cells and oral squamous cell carcinoma were used to perform a single-cell co-culture experiment on the microfluidic platform for live multiple single-cell interaction studies.

This report describes a microfluidic chip-based method to set up a single cell culture experiment in which high-efficiency pairing and microscopic analysis of multiple single cells can be achieved.

使用微流体芯片以确定性方式建立基于单细胞的共培养物

Cell co-culture assays have been widely used for studying cell-cell interactions between different cell types to better understand the biology of diseases ...

Single-Cell Optical Action Potential Measurement in Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes

Conventional intracellular microelectrode techniques to quantify cardiomyocyte electrophysiology are extremely complex, labor intensive, and typically carried out in low throughput. Rapid and ongoing expansion of induced pluripotent stem cell (iPSC) technology presents a new standard in cardiovascular research and alternate methods are now necessary to increase throughput of electrophysiological data at a single cell level. VF2.1Cl is a recently derived voltage sensitive dye which provides a rapid single channel, high magnitude response to fluctuations in membrane potential. It possesses kinetics superior to those of other existing voltage indicators and makes available functional data equivalent to that of traditional microelectrode techniques. Here, we demonstrate simplified, non-invasive action potential characterization in externally paced human iPSC derived cardiomyocytes using a modular and highly affordable photometry system.

Here we describe optical acquisition and characterization of action potentials from induced pluripotent stem cell derived cardiomyocytes using a high-speed modular photometry system.

人类诱导多能干细胞衍生心肌细胞中的单细胞光学作用潜在测量

Conventional intracellular microelectrode techniques to quantify cardiomyocyte electrophysiology are extremely complex, labor intensive, and typically ...