脂质质谱成像揭示三氯生促进三维肝癌肿瘤细胞球增长的相关机理

三氯生(triclosan, TCS)作为一种广谱抗菌剂被广泛应用于多种日常消费品中。当前研究表明，TCS暴露可以促进肝癌肿瘤增长，但涉及的相关脂质代谢机理尚不完全清楚。基于此，本研究建立了TCS暴露的肝癌肿瘤细胞球模型，利用质谱成像技术分析对照组和暴露组间脂质小分子在肿瘤细胞球内丰度和分布的差异。结果表明，6μmol/L TCS暴露可以显著促进肝癌肿瘤细胞球的增长，并引起脂质代谢的变化。27种脂质代谢小分子(含19种甘油磷脂、3种甘油酯和5种鞘脂)的丰度在对照组和暴露组的肿瘤细胞球内发生了显著性的变化。在暴露组的19种甘油磷脂中，16种在肿瘤细胞球外围增殖区发生了显著性上调；在3种甘油酯中，1种在外围增殖区发生了显著性上调，2种在内部凋亡区发生了显著性下调；5种鞘脂在肿瘤细胞球内部凋亡区均发生了显著性下调。可见，TCS可能是通过促进肿瘤细胞球外围细胞的增殖以及抑制内层细胞的凋亡来促进三维肿瘤细胞球的增长。该结果可为进一步探讨环境污染物对肿瘤发展影响的分子机制提供参考。     

正电子发射断层显像与质谱成像互补结合寻找肿瘤相关分子标志物初探

正电子发射断层(PET)显像可以活体、无创反映疾病的特征分子改变,如利用~(18)氟-脱氧葡萄糖(~(18)F-FDG)反映肿瘤的葡萄糖代谢,以及利用~(18)氟-硝基咪唑(~(18)F-FMISO)反映肿瘤的乏氧状态等。质谱成像(MSI)不需要标记和复杂准备,可以离体检测到成百上千种分子在病灶内的精确分布信息,但这些分子的功能往往不易明确。本研究利用BALB/c裸鼠4T1乳腺癌肿瘤模型,将PET显像和电喷雾MSI结合,通过图像对比和统计软件分析,分别找到了与PET糖代谢图像和乏氧图像匹配的系列分子,通过查找人类代谢组数据库,初步确定了这些分子的组成。基于以上,本研究初步证实了PET显像和质谱成像互补结合寻找特征分子标志物的可行性。     

基于快速蒸发离子化质谱实时检测空气油炸鲳鱼的脂质组学轮廓

快速蒸发离子化质谱（rapid evaporative ionization mass spectrometry, REIMS）是一种无需样品预处理的新型质谱技术，通过手持智能手术刀切割样品采集数据从而获得脂质组学轮廓。本研究采用REIMS技术和主成分分析（principal component analysis, PCA）、隐结构正交投影（orthogonal projection to latent structure, OPLS）等数理统计方法实时监测鲳鱼在空气油炸过程中脂质组学轮廓变化，并探究不同空气油炸温度对鲳鱼肌肉组织脂质组成的影响。通过单因素条件优化得到适宜的REIMS系统参数，电刀输出功率20 W、电刀切割功率1 mm/s、辅助溶剂流速100 μL/min，从而获得稳定可靠的质谱轮廓图。在PCA分析的基础上进行OPLS分析，得到10个重要的特征离子（VIP>1），其中PE（O-16∶1/22∶6）只在原料中检测到，为4.61%；此外，PE（22∶5/22∶6）在10个磷脂离子中的不饱和度最高，其相对含量随油炸温度的升高而降低，同样可见于PA（18∶1/22∶6）和PI（18∶0/22∶6），说明磷脂的饱和度有随油炸温度升高而上升的趋势。经方法验证显示，REIMS检测离子的信噪比范围为49.58~205.30，日内和日间精密度的相对标准偏差为3.10%~7.28%，灵敏度和精密度均较高，因此，该方法将成为脂质组学研究过程中一种简单、高效、准确的新型技术手段。     

Era蛋白（E.coli ras-like protein）-一个可能参与真、原细胞信号调控的新分子开关

充足的证据表明G蛋白作为真核细胞的重要分子开关参与细胞的增殖调控以及部分代谢调控过程。而近来在大肠杆菌中新发现的Era蛋白（E.coli ras-like protein）则是与已知的三聚体G蛋白和小分子G蛋白不同的一种新的GTP结合蛋白。进一步的研究发现该类GTP结合蛋白不仅存在于原核的大肠杆菌中,而且在高等植物、人类细胞中均含有该蛋白的同源蛋白。大肠杆菌的Era蛋白主要位于细胞膜的内侧,细胞质中也有一定的分布;一些证据表明,真核细胞ERA（ERG）蛋白来源于原核细胞,定位于线粒体或者叶绿体。近来的研究证据表明ERA或者ERG蛋白有可能担负着与其它两类G蛋白同样重要的分子开关功能。已有的研究表明Era蛋白参与调节原核生物的细胞分裂、细胞周期以及部分细胞代谢过程;在哺乳动物细胞中,同源蛋白ERA可能与细胞周期的G1期调控以及细胞凋亡有关;真核植物中相关研究报道尚少,推测该蛋白可能与种子的正常发育有关。本文主要介绍原核Era蛋白和真核ERA蛋白的结构特点以及功能研究进展。     

T细胞与K562细胞共培养的AFM观察

人类机体的免疫系统很难彻底清除肿瘤细胞,了解T淋巴细胞杀伤肿瘤细胞的整个过程的机理,将为提高免疫系统杀灭肿瘤的效率提供知识基础。本文采用原子力显微镜与倒置显微镜在细胞层面上观察T淋巴细胞进攻杀伤人慢性粒细胞性白血病细胞株——K562细胞的过程,并对T细胞与K562细胞共培养前后的表面形貌和生物机械性质进行表征。结果显示,与培养前相比,共培养后2种细胞数目之和减少,2种细胞的表面形貌和机械力学性质均出现很大差异,表现为:K562细胞,平均粗糙度(Ra)降低,细胞平均高度(Mh)降低,细胞表面出现5～8 cm的孔洞,有的细胞甚至完全破裂溶解。多个T细胞的统计分析结果显示,共培养前,T细胞为静息状态,而共培养后Ra和Mh都显著增加。该方法为研究免疫系统与肿瘤相互作用的机制提供重要的切入点。     

激光控制化学反应

因为激光的精确性，人们希望利用它使大分子内的化学键有选择地断裂或形成。但是试验结果令人失望，在激光停顿间隙，分子能量就会自发重新分布，完全抵消激光的作用。研究者们提出了各种方案，以期控制激光，解决这个问题。在小分子体系却一直未告突破。最近德国科学家Ａｓｓｉｏｎ等利用质谱仪和计算机对整个过程进行控制，成功地完成了两个激光断裂化学键的反应。激光控制化学反应     

PET-CT定位在非小细胞肺癌放射治疗中的应用与挑战分析

传统的放射治疗是按照CT图像上的组织密度差异性、大小实现肿瘤靶区的勾画，但是，这种解剖影像还无法更为有效地对肿瘤大小、肿瘤范围详细研究，特别是存在炎症、瘢痕的时候。所以，还需要更为精密的方法。PET-CT定位（正电子断层扫描）显像是通过不同核素示踪剂对肿瘤细胞生物标志物的变化情况进行研究，如细胞代谢、增殖情况等，都能为疾病诊断提供重要关键信息。本文重点分析PET-CT定位在非小细胞肺癌放射治疗中的应用，以保证为精确放疗提供重要条件。     

V型球调节阀涡流噪声模拟及降噪设计

针对V型球调节阀流制噪声过大的问题，通过大涡模拟和声比拟方程相结合的方法，对V型球调节阀的内外声场进行了三维仿真模拟以及试验测试，研究了阀门涡流噪声分布特征。研究发现，高声压级频率集中在0～1 200 Hz，在整个频段上声壁面压力脉动（AWPF）对噪声贡献远高于湍流壁面压力脉动（TWPF）。基于涡声理论探究了V型球阀芯的开孔参数对噪声的影响，改进后的阀门流致噪声下降了约10 dB(A)。研究结果可为低噪声V型球调节阀的设计提供计算方法和优化方向。     

液相色谱-质谱联用技术用于人参皂甙Rg3的药物代谢及动力学研究

Rg3是从红参(Red Panax ginseng)中发现的一种微量人参皂甙.药理实验表明,它在小鼠体内具有抑制肿瘤转移的活性及在体外有抑制肿瘤细胞扩散的活性.对其体外代谢的研究目前只见一例用人体肠道菌群体外厌氧培养产生水解脱糖的代谢产物的报导,而对其体内的研究目前只见于人口服后在人体内的动力学报导,但其在动物体内的代谢尚不清楚,因此有必要研究其在动物体内的动力学及代谢详情.     

纳米级正十六烷润滑膜分子排列方式的实验研究

针对厚度为纳米量级的液体正十六烷润滑膜，在球－盘点接触区内的分子排列结构开展实验研究。采用自行研制的在线测量系统，基于偏振拉曼光谱技术和相对光强膜厚测量技术分析处于不同润滑状态下的润滑膜分子排列结构和成因。结果表明:接触区内十六烷静态液膜的分子主链平行于固体表面，但在摩擦平面内的取向随机分布;较低速度下液膜分子排列结构与静态液膜相近;进入弹流润滑状态后，液膜分子排列结构呈无序的流体状态；在膜厚处于薄膜润滑阶段时，液膜分子有沿滚动速度方向取向的趋势。     

衍生化技术在MALDI质谱成像中的应用进展

近年来，基质辅助激光解吸离子化（matrix-assisted laser desorption ionization, MALDI）质谱成像（mass spectrometry imaging, MSI）技术发展迅速，在很多领域均有广泛应用。质谱成像技术虽然可以同时得到上百个化合物的数据，但是对于低丰度、离子化效率低和易受基质峰干扰的化合物的成像分析仍然极具挑战。为了提高质谱成像中目标分子的信号响应，将原位衍生化方法应用于质谱成像技术中是非常必要的。衍生化方法与质谱成像的结合已成功实现了不同类型目标分析物的成像分析，且均展现了优异的效果。本文综述了样本上原位衍生化方法在MALDI质谱成像中的应用，包括用于含有羧基、氨基、醛基等活性基团的目标分子的衍生化试剂和衍生化反应，以及衍生化的基质选择和试剂的涂覆装置，并展望了衍生化方法结合MALDI质谱成像技术的发展趋势。     

基于高分辨质谱技术的整体动物体内药物成像分析新方法研究

质谱分子成像技术作为体内药物分析的新兴工具受到越来越多的关注,其中生物体内复杂基质的干扰是面临的关键问题之一。本研究利用高分辨质谱技术的优势,采用空气动力辅助离子化质谱成像方法（AFAI-MSI）,建立了高特异性的整体动物体内药物成像分析新方法,以提高体内药物成像分析结果的准确性和可靠性。以候选新药右旋娃儿藤宁碱（S-(+)-deoxytylophorinidine, CAT）为研究对象,采用高分辨质谱全扫描与靶向扫描相结合的方式,对整体动物体内药物的分布进行AFAI-MSI分析。结果表明,该方法能够准确地反映药物特异性分布和处置情况。通过一次质谱成像实验,从整体动物水平同时实现了候选新药体内分布和药物干预下内源性代谢物的成像分析,为候选新药的早期研发提供思路与手段。     

On-tissue chemical derivatization in mass spectrometry imaging

Mass spectrometry imaging (MSI) combines molecular and spatial information in a valuable tool for a wide range of applications. Matrix-assisted laser desorption/ionization (MALDI) is at the forefront of MSI ionization due to its wide availability and increasing improvement in spatial resolution and analysis speed. However, ionization suppression, low concentrations, and endogenous and methodological interferences cause visualization problems for certain molecules. Chemical derivatization (CD) has proven a viable solution to these issues when applied in mass spectrometry platforms. Chemical tagging of target analytes with larger, precharged moieties aids ionization efficiency and removes analytes from areas of potential isobaric interferences. Here, we address the application of CD on tissue samples for MSI analysis, termed on-tissue chemical derivatization (OTCD). MALDI MSI will remain the focus platform due to its popularity, however, alternative ionization techniques such as liquid extraction surface analysis and desorption electrospray ionization will also be recognized. OTCD reagent selection, application, and optimization methods will be discussed in detail. MSI with OTCD is a powerful tool to study the spatial distribution of poorly ionizable molecules within tissues. Most importantly, the use of OTCD−MSI facilitates the analysis of previously inaccessible biologically relevant molecules through the adaptation of existing CD methods. Though further experimental optimization steps are necessary, the benefits of this technique are extensive.     

Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: An update covering the period 1999-2000

This review describes the use of matrix-assisted laser desorption/ionization (MALDI) mass spectrometry for the analysis of carbohydrates and glycoconjugates and continues coverage of the field from the previous review published in 1999 (D. J. Harvey, Matrix-assisted laser desorption/ionization mass spectrometry of carbohydrates, 1999, Mass Spectrom Rev, 18:349-451) for the period 1999-2000. As MALDI mass spectrometry is acquiring the status of a mature technique in this field, there has been a greater emphasis on applications rather than to method development as opposed to the previous review. The present review covers applications to plant-derived carbohydrates, N- and O-linked glycans from glycoproteins, glycated proteins, mucins, glycosaminoglycans, bacterial glycolipids, glycosphingolipids, glycoglycerolipids and related compounds, and glycosides. Applications of MALDI mass spectrometry to the study of enzymes acting on carbohydrates (glycosyltransferases and glycosidases) and to the synthesis of carbohydrates, are also covered.     

Microorganism characterization by single particle mass spectrometry

In recent years a major effort by several groups has been undertaken to identify bacteria by mass spectrometry at the single cell level. The intent of this review is to highlight the recent progress made in the application of single particle mass spectrometry to the analysis of microorganisms. A large portion of the review highlights improvements in the ionization and mass analysis of bio-aerosols, or particles that contain biologically relevant molecules such as peptides or proteins. While these are not direct applications to bacteria, the results have been central to a progression toward single cell mass spectrometry. Developments in single particle matrix-assisted laser desorption/ionization (MALDI) are summarized. Recent applications of aerosol laser desorption/ionization (LDI) to the analysis of single microorganisms are highlighted. Successful applications of off-line and on-the-fly aerosol MALDI to microorganism detection are discussed. Limitations to current approaches and necessary future achievements are also addressed.     

Vacuum compatible sample positioning device for matrix assisted laser desorption∕ionization Fourier transform ion cyclotron resonance mass spectrometry imaging

The high mass accuracy and resolving power of Fourier transform ion cyclotron resonance mass spectrometers (FT-ICR MS) make them ideal mass detectors for mass spectrometry imaging (MSI), promising to provide unmatched molecular resolution capabilities. The intrinsic low tolerance of FT-ICR MS to RF interference, however, along with typically vertical positioning of the sample, and MSI acquisition speed requirements present numerous engineering challenges in creating robotics capable of achieving the spatial resolution to match. This work discusses a two-dimensional positioning stage designed to address these issues. The stage is capable of operating in ～1 × 10(-8) mbar vacuum. The range of motion is set to 100 mm × 100 mm to accommodate large samples, while the positioning accuracy is demonstrated to be less than 0.4 micron in both directions under vertical load over the entire range. This device was integrated into three different matrix assisted laser desorption∕ionization (MALDI) FT-ICR instruments and showed no detectable RF noise. The "oversampling" MALDI-MSI experiments, under which the sample is completely ablated at each position, followed by the target movement of the distance smaller than the laser beam, conducted on the custom-built 7T FT-ICR MS demonstrate the stability and positional accuracy of the stage robotics which delivers high spatial resolution mass spectral images at a fraction of the laser spot diameter.     

Imaging mass spectrometry

Imaging mass spectrometry combines the chemical specificity and parallel detection of mass spectrometry with microscopic imaging capabilities. The ability to simultaneously obtain images from all analytes detected, from atomic to macromolecular ions, allows the analyst to probe the chemical organization of a sample and to correlate this with physical features. The sensitivity of the ionization step, sample preparation, the spatial resolution, and the speed of the technique are all important parameters that affect the type of information obtained. Recently, significant progress has been made in each of these steps for both secondary ion mass spectrometry (SIMS) and matrix-assisted laser desorption/ionization (MALDI) imaging of biological samples. Examples demonstrating localization of proteins in tumors, a reduction of lamellar phospholipids in the region binding two single celled organisms, and sub-cellular distributions of several biomolecules have all contributed to an increasing upsurge in interest in imaging mass spectrometry. Here we review many of the instrumental developments and methodological approaches responsible for this increased interest, compare and contrast the information provided by SIMS and MALDI imaging, and discuss future possibilities.     

Mass spectrometry imaging under ambient conditions

Mass spectrometry imaging (MSI) has emerged as an important tool in the last decade and it is beginning to show potential to provide new information in many fields owing to its unique ability to acquire molecularly specific images and to provide multiplexed information, without the need for labeling or staining. In MSI, the chemical identity of molecules present on a surface is investigated as a function of spatial distribution. In addition to now standard methods involving MSI in vacuum, recently developed ambient ionization techniques allow MSI to be performed under atmospheric pressure on untreated samples outside the mass spectrometer. Here we review recent developments and applications of MSI emphasizing the ambient ionization techniques of desorption electrospray ionization (DESI), laser ablation electrospray ionization (LAESI), probe electrospray ionization (PESI), desorption atmospheric pressure photoionization (DAPPI), femtosecond laser desorption ionization (fs‐LDI), laser electrospray mass spectrometry (LEMS), infrared laser ablation metastable‐induced chemical ionization (IR‐LAMICI), liquid microjunction surface sampling probe mass spectrometry (LMJ‐SSP MS), nanospray desorption electrospray ionization (nano‐DESI), and plasma sources such as the low temperature plasma (LTP) probe and laser ablation coupled to flowing atmospheric‐pressure afterglow (LA‐FAPA). Included are discussions of some of the features of ambient MSI for example the ability to implement chemical reactions with the goal of providing high abundance ions characteristic of specific compounds of interest and the use of tandem mass spectrometry to either map the distribution of targeted molecules with high specificity or to provide additional MS information on the structural identification of compounds. We also describe the role of bioinformatics in acquiring and interpreting the chemical and spatial information obtained through MSI, especially in biological applications for tissue diagnostic purposes. Finally, we discuss the challenges in ambient MSI and include perspectives on the future of the field. © 2012 Wiley Periodicals, Inc., Mass Spec Rev 32:218–243, 2013