常压电离质谱在脂质精确结构解析中的研究进展

脂类化合物的结构和功能与细胞生理过程密切相关,脂质结构的精确解析对探索脂质的生物学功能起着至关重要的作用。常压电离质谱技术的出现为常压敞开环境条件下的原位、实时、直接、快速生物脂质分析和组学研究提供了重要的手段。随着常压电离质谱技术在脂质分析和脂质组学研究的不断深入,对脂质结构特别是碳碳双键(C‖C)位置的精细解析就显得尤为重要。该文详细阐述了基于Paternò-Büchi反应、环氧化、臭氧诱导解离、紫外光解离的常压电离质谱技术,以及这些技术在脂质C‖C位置精确鉴定及异构体区分的应用,并展望了常压电离质谱在脂质化合物精确结构解析方面的发展趋势。     

血浆中长链不饱和脂肪酸的毛细管气相色谱分析

脂类物质是细胞膜的主要组成,具有多种重要的生物功能。通过检测血浆中脂肪酸水平,可以研究某些重要疾病与脂质及脂肪酸的关系。特别是长链不饱和脂肪酸,由于它们是前列腺素的前体,更具有重要意义,血浆中长链不饱和脂肪酸,其中8,11,14—廾碳三烯酸(C_(20:)     

血清脂质组学研究中多重离子化液相色谱-质谱方法的比较

系统地比较了3种常用的离子化技术电喷雾电离(ESI)、大气压化学电离(APCI)、大气压光致电离(APPI)对脂类化合物的离子化效率、检测灵敏度和覆盖范围,以探讨多重离子化液相色谱-质谱(LC-MS)方法在血清脂质组学研究中的适用性.血清样本经甲基叔丁基醚萃取后,采用Ascentiss Express C8 色谱柱(150 mm×2.1 mm, 2.7 μm)和二元线性梯度洗脱分离,流动相(A)为乙腈-水(3∶2, V/V, 含0.1%甲酸, 10 mmol/L甲酸铵),B为异丙醇-乙腈(9∶1, V/V, 含0.1%甲酸,10 mmol/L甲酸铵),分别采用ESI、APCI和APPI离子源正、负离子模式进行质谱检测.结果表明,ESI离子源对脂肪酸类、甘油脂类、甘油磷脂类化合物、鞘磷脂类化合物的离子化效率最高,对异戊烯醇脂类化合物的离子化效率与APPI离子源相当,APPI离子源对胆固醇(酯)类化合物的检测灵敏度最高,APCI离子源对各类化合物的检测灵敏度均低于ESI或APPI离子源;采用ESI和APPI离子源相结合的LC-MS脂质组学分析方法可以提高分析方法的整体灵敏度和血清中脂类信息检测的完整性.     

高效液相色谱-电感耦合等离子体质谱法测定虾油中2种无机砷

正虾油中含有丰富的不饱和脂肪酸磷脂质及虾青素等生物性脂质~([1]),具有抗衰老、抗氧化、清除自由基、降血脂、健脑益智等多种功能,其在食品和保健品等多个领域得到应用,但虾油中砷含量较高,这使其在食品和保健品领域的应用受到了一定限制~([2])。虾油的食用安全性,特别是其中所含的有毒重金属含量备受关注~([3])。砷在海产品中富集倾向明显,砷的毒性与其存在形态密切相关。砷主要有无机砷和     

基于芯片的直接进样质谱法和气相色谱-质谱测定莱茵衣藻中的极性脂类

目前微藻的脂类分析主要侧重于脂肪酸酯、甘油三酯以及细胞内总脂的分析, 忽视了极性脂类的分析. 本研究建立了一个基于芯片的全自动电喷雾进样系统联用线性离子阱质谱的技术, 用于分析莱茵衣藻中的极性脂类. 通过数据库Lipidblast鉴定出了35种不同种类的极性脂类, 并首次鉴定出20种甜菜碱脂类. 同时利用了GC/TOF-MS来检测莱茵衣藻中的游离脂肪酸, 发现亚油酸、亚麻酸和棕榈酸是莱茵衣藻中含量最丰富的三种脂肪酸. 建立的脂类分析方法为微藻脂类种类全面综合的分析提供了方法上的参考.     

胆囊组织、组织细胞膜及细胞株的FTIR研究

研究了不同病理生理状态的胆囊组织、胆囊组织细胞膜及胆囊癌细胞株的傅里叶变换红外光谱的相关性.结果显示,与正常组织比较,胆囊癌组织中脂质相关谱带(2955,2920,2870,2850和1740 cm-1)与蛋白相关谱带(1550 cm-1)强度降低;胆囊癌细胞株中脂质相关谱带与蛋白相关谱带(1550 cm-1)强度明显增加;胆囊癌组织细胞膜中脂质相关谱带强度明显增加;核酸相关吸收谱带强度变化在胆囊癌组织和胆囊癌细胞株中一致,在细胞膜中消失;I1460/I1400比值在组织、细胞株和细胞膜层面变化一致,与正常组织相比均有所减少.结果表明,与胆囊癌组织相比,胆囊癌细胞株和胆囊癌组织细胞膜的红外光谱发生了显著变化:癌组织的脂类和蛋白质的相对含量降低;癌细胞株的脂质和蛋白相对含量增加;胆囊癌组织细胞膜的脂质和蛋白相对含量升高.从组织、细胞和细胞膜3个层面阐述了癌变的分子光谱变化.I1460/I1400比值的变化在组织、细胞株和细胞膜层面变化一致,对此指标的深入研究有望获得一个良好的临床诊断指标.     

几种有利健脑的营养物质

介绍了脑需要的8种主要营养素——脂肪、维生素C、钙质、糖、蛋白质、维生素B、维生素A及维生素E的健脑功能及健脑食物.     

自组装脂类微管金属化制备镍螺旋带复合微结构

脂类分子自组装可制备脂类微管, 脂类微管是由螺旋带缠绕形成的稳定结构. 本文以脂类微管为前体, 利用一种不同的催化方法, 化学镀沉积金属Ni, 制备一种新型脂类-镍螺旋带复合微结构. 螺旋带的平面沉积均匀分布的Ni纳米颗粒, 平均大小为40~60 nm; 而带边缘生成多层Ni纳米线, 镍线的层状结构与脂类膜的多层结构有关. 脂类-镍螺旋带形状不规则, 长度明显小于脂类微管, 其形成与脂类微管的螺旋带缠绕结构和催化过程密切相关. 测试表明, 随着质量百分比的升高, 微波介电性能升高. 该螺旋带复合微结构可望用于新型电活性材料的设计和开发.     

分子自组装脂类微管的螺旋带特征分析

利用联乙炔基甘油磷脂酰胆碱分子的自组装特性,制备得到脂类微管结构,并在大量观察基础上,对脂类微管的螺旋带特征进行分析归纳．观察表明脂类微管是由螺旋带紧密缠绕形成的稳定结构,具有明显的螺旋缠绕特征;同时体系中存在少量不同形态的松驰螺旋带．体系中存在有单层脂膜包埋的螺旋带,这是一种新的结构形态．螺旋带边缘有明显的错位和分层现象,端部具有不同于其它区域的松驰现象．脂类微管的这些特征对其表面纳米颗粒的沉积产生很大的影响,金属钯和镍纳米颗粒在螺旋带边缘的分层沉积可清楚地显示脂类微管螺旋带的错位和分层特征．金属钯的分层沉积特征可尝试用于标志自组装膜的脂类双层数;同时,自组装脂类螺旋带的研究可用于揭示脂类分子自组装的本质,并在生物矿化和生物膜力学研究方面有重要意义．     

红外光谱和拉曼光谱法分析玉米种子的成分

采用傅立叶红外光谱法(FTIR)及拉曼光谱分析了玉米种子不同部位的成分。实验表明,不同部位蛋白质、脂类和碳水化合物的特征吸收峰的相对强弱是不同的。玉米种子的胚中这3种物质的特征吸收峰强度较为均匀,差别不大。胚乳中脂类特征吸收峰最强,显示胚乳中脂类占据主导。白色的糊粉层则以碳水化合物为主。而外层黄色部位蛋白质和碳水化合物的吸收峰较强,脂类的吸收峰很小。拉曼光谱分析可以看到玉米种子的类胡萝卜素含量从黄色的外层到胚逐渐降低。     

Compact cancer biomarkers discovery using a swarm intelligence feature selection algorithm

Biomarker discovery is a typical application from functional genomics. Due to the large number of genes studied simultaneously in microarray data, feature selection is a key step. Swarm intelligence has emerged as a solution for the feature selection problem. However, swarm intelligence settings for feature selection fail to select small features subsets. We have proposed a swarm intelligence feature selection algorithm based on the initialization and update of only a subset of particles in the swarm. In this study, we tested our algorithm in 11 microarray datasets for brain, leukemia, lung, prostate, and others. We show that the proposed swarm intelligence algorithm successfully increase the classification accuracy and decrease the number of selected features compared to other swarm intelligence methods.     

Characterization of lipid extracts from brain tissue and tumors using Raman spectroscopy and mass spectrometry

Brain tissue is characterized by high lipid content. The amount of lipids decreases, and its composition changes in the most frequent primary brain tumor, the glioma. Scope of the current paper was to extract quantitatively lipids from porcine and human brain tissue as well as from five human gliomas using a modified protocol according to Folch. The lipid extracts were studied by Raman spectroscopy with 785 nm excitation and by mass spectrometry with electron impact ionization. Porcine and human brain tissues have similar water and lipid content and show similar Raman and mass spectra. In contrast, gliomas are characterized by increased water content and decreased lipid content. Elevated phosphatidylcholine to cholesterol ratios in lipid extracts of gliomas were indicated by Raman bands of the choline group and cholesterol. Due to its higher sensitivity, mass spectrometry detected increased levels of cholesterol ester relative to cholesterol in lipid extracts of gliomas. For comparison, thin tissue sections were prepared from the glioma specimens before lipid extraction; infrared spectroscopic images were recorded and analyzed by a supervised classification model. This study demonstrates how to improve the analysis of brain tumors and to complement the diagnosis of brain pathologies using a multimodal approach.     

Quantification of brain lipids by FTIR spectroscopy and partial least squares regression

Brain tissue is characterized by high lipid content. Its content decreases and the lipid composition changes during transformation from normal brain tissue to tumors. Therefore, the analysis of brain lipids might complement the existing diagnostic tools to determine the tumor type and tumor grade. Objective of this work is to extract lipids from gray matter and white matter of porcine brain tissue, record infrared (IR) spectra of these extracts and develop a quantification model for the main lipids based on partial least squares (PLS) regression. IR spectra of the pure lipids cholesterol, cholesterol ester, phosphatidic acid, phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, phosphatidylinositol, sphingomyelin, galactocerebroside and sulfatide were used as references. Two lipid mixtures were prepared for training and validation of the quantification model. The composition of lipid extracts that were predicted by the PLS regression of IR spectra was compared with lipid quantification by thin layer chromatography.     

铅对脑发育的影响及与智力关系分析

讨论了铅对脑发育期中枢神经系统的影响,并调查了30名学习困难、成绩差的学龄儿童血铅的含量情况。结果表明,血铅今量与智力有一定关系。     

All-oxide-based and metallic electrode-free artificial synapses for transparent neuromorphic computing

The extraordinary abilities of the human brain rely on the functioning of biological synapses in the nervous system. Emulating human brain activity for neuromorphic computing has been an alluring prospect in artificial intelligence, and this would become possible with the development of an efficient artificial synapse. The human brain assimilates most information through visual perception. Therefore, optoelectronic synapses can be considered an important keystone of neuromorphic computing due to their efficient ability to process optoelectronic input signals. In this work, a metallic electrode-free, all-oxide-based optoelectronic synapse was developed that demonstrated efficient and repeatable electronic and photonic synaptic plasticity behaviour. A unique artificial synapse with an n–n heterostructure was developed using ZnO and V₂O₅. This artificial synapse structure has high optical transparency and does not require a metallic electrode for data acquisition. The device exhibits resistive switching memory behaviour, along with electronic and photonic synaptic behaviour. The storing and erasing of information, as well as learning-experience behaviour, was also successfully demonstrated in the V₂O₅/ZnO artificial synapse. This work could therefore be beneficial to the development of artificial intelligence when transparent and metallic electrode-free synaptic devices are considered necessary.     

Iodine concentration in different human brain parts

Iodine is one of the most important essential elements as demonstrated by the fact that its deficiency can cause goitre. Nevertheless, quantitative data on its concentration in biological materials, especially in the human brain, are scarce. There is therefore a demand for accurate and reliable information on iodine in these types of samples. The purpose of the present work was to determine the concentration of total iodine in some control human brain parts by rapid radiochemical neutron activation analysis. Our second goal was to determine I distribution between lipid fraction and in brain tissue without lipid by applying two types of solvent extraction methods. The results were checked by the analysis of biological standard reference materials with certified or literature values for iodine and good agreement was found.     

Major differences in the behaviour of carbon paste and carbon fibre electrodes in a protein-lipid matrix: implications for voltammetry in vivo.

The widely documented differences in behaviour of carbon fibre electrodes (CFEs) and carbon paste electrodes (CPEs) used for neurochemical analysis in vivo were investigated. Differential staircase voltammetry was used to study the electrooxidation of ascorbic acid (AA) at CFEs and CPEs in the presence of major constituents of brain tissue, viz., protein, lipid or a mixture of both. Both electrode types were poisoned by protein, reflected in positive shifts in the AA voltammetric peak potential, and also peak broadening, following exposure of the electrodes to protein solution. In contrast, CFEs and CPEs responded very differently to exposure to lipid suspension: CFEs exhibited poisoning whereas CPEs showed enhanced electron transfer kinetics for AA. This significant difference in the response of the two carbon materials to lipid was further demonstrated by showing that lipid could reverse the poisoning caused by protein for CPEs but not CFEs. It appears, therefore, that proteins adsorb on both CPEs and CFEs, hindering electron transfer from AA to the electrode surface. Surfactant lipid molecules, in contrast, have a cleaning effect on CPEs, removing pasting oil and adsorbed proteins from the CPE surface. These results provide an explanation for the stability of CPEs in brain tissue and for the contrasting instability of CFEs in the same environment. The data also suggest that a lipid-protein matrix represents a valuable in vitro chemical model of brain tissue that should allow a truer characterisation in vitro of new and existing in vivo sensors, reducing the need for animal experiments in these studies.     

Prolongation of life span of stroke-prone spontaneously hypertensive rats (SHRSP) ingesting persimmon tannin

The effects of persimmon tannin on pathophysiological changes in stroke-prone spontaneously hypertensive rats (SHRSP) were investigated. When the persimmon tannin was chronically ingested by SHRSP, the life span was significantly prolonged, yet the effect on blood pressure was slight. The incidences of brain hemorrhage and infarction were also significantly decreased by this treatment. To elucidate the mechanisms involved in these events, the effects of condensed tannins, including persimmon tannin, on free radicals and lipid peroxidation were examined in vitro. Using electron spin resonance analysis, we found that these tannins have a potent, concentration-dependent scavenging action toward active oxygen free radicals. These tannins strongly inhibited lipid peroxidation in rat brain homogenates, in a concentration-dependent manner. Persimmon tannin inhibited lipid peroxidation similarly to (-)-epigallocatechin. Persimmon tannin was 20 times more effective than alpha-tocopherol in terms of the 50%-inhibitory concentration. The radical scavenging action and inhibition of lipid peroxidation by persimmon tannin may explain, in part, the prolongation of the life span of the SHRSP ingesting persimmon tannin.     

MALDI Mass Spectrometric Imaging of Lipids in Rat Brain Injury Models

Matrix-assisted laser desorption ionization/ionization imaging mass spectrometry (MALDI IMS) with a time-of-flight analyzer was used to characterize the distribution of lipid molecular species in the brain of rats in two injury models. Ischemia/reperfusion injury of the rat brain after bilateral occlusion of the carotid artery altered appearance of the phospholipids present in the hippocampal region, specifically the CA1 region. These brain regions also had a large increase in the ion abundance at m/z 548.5 and collisional activation supported identification of this ion as arising from ceramide (d18:1/18:0), a lipid known to be associated with cellular apoptosis. Traumatic brain injury model in the rat was examined by MALDI IMS and the area of damage also showed an increase in ceramide (d18:1/18:0) and a remarkable loss of signal for the potassium adduct of the most abundant phosphocholine molecular species 16:0/18:1 (PC) with a corresponding increase in the sodium adduct ion. This change in PC alkali attachment ion was suggested to be a result of edema and influx of extracellular fluid likely through a loss of Na/K-ATPase caused by the injury. These studies reveal the value of MALDI IMS to examine tissues for changes in lipid biochemistry and will provide data needed to eventually understand the biochemical mechanisms relevant to tissue injury.     

Densitometrische Mikrobestimmung von Lipiden nach Dünnschicht-Chromatographie des Gesamtlipidextrakts

A thin-layer chromatographic-densitometric method is described for the quantitative microanalysis of brain lipids (5 to 25 μg) from the total lipid extract. Three lipid groups (gangliosides, non-phosphatides and phosphatides) can be separated and quantitated by two techniques: either directly from the total lipid extract or after prefractionation. The relative standard deviation of five measurements was 1.5±0.5% for non-phosphatides and phosphatides and 2.0±0.5% for gangliosides by the first technique, and 3.5±0.5% for all of them by the second technique. Both techniques are discussed.