MALDI‐FT‐ICR‐MS for archaeological lipid residue analysis

Soft‐ionization methods are currently at the forefront of developing novel methods for analysing degraded archaeological organic residues. Here, we present little‐used soft ionization method of matrix assisted laser desorption/ionization‐Fourier transform‐ion cyclotron resonance‐mass spectrometry (MALDI‐FT‐ICR‐MS) for the identification of archaeological lipid residues. It is a high‐resolution and sensitive method with low limits of detection capable of identifying lipid compounds in small concentrations, thus providing a highly potential new technique for the analysis of degraded lipid components. A thorough methodology development for analysing cooked and degraded food remains from ceramic vessels was carried out, and the most efficient sample preparation protocol is described. The identified components, also controlled by independent parallel analysis by gas chromatography‐mass spectrometry (GC‐MS) and gas chromatography‐combustion‐isotope ratio mass spectrometry (GC‐C‐IRMS), demonstrate its capability of identifying very different food residues including dairy, adipose fats as well as lipids of aquatic origin. The results obtained from experimentally cooked and original archaeological samples prove the suitability of MALDI‐FT‐ICR‐MS for analysing archaeological organic residues. Sample preparation protocol and identification of compounds provide future reference for analysing various aged and degraded lipid residues in different organic and mineral matrices.     

2,5‐Dihydroxybenzoic acid solution in MALDI‐MS: ageing and use for mass calibration

2,5‐Dihydroxybenzoic acid (DHB) is one of the most widely used and studied matrix compounds in matrix‐assisted laser desorption/ionization (MALDI) mass spectrometry. However, the influence of ageing of the DHB solution on the MALDI mass spectra has not been yet systematically studied. In this work, the possible changes occurring in the acidified acetonitrile/water solution of the MALDI matrix compound DHB during 1‐year usage period have been monitored with MALDI‐Fourier transform ion cyclotron resonance mass spectrometer (MALDI‐FT‐ICR‐MS) and attenuated total reflectance Fourier transform infrared (ATR‐FT‐IR) spectroscopy. No significant ageing products have been detected. The ability of the aged DHB solution to act as a MALDI matrix was tested with two materials widely used in art and conservation – bone glue (a proteinaceous material) and shellac resin (a resinous material) – and good results were obtained. A number of peaks in the mass spectra measured from the DHB solution were identified, which can be used for internal calibration of the mass axis. Copyright © 2014 John Wiley & Sons, Ltd.     

A new enzymatic method for determination of E. coli

Inthispaper,arapid,sensitiveandsimpleenzymaticmethodfordetectingtheE.coltcellshasbeenestablished.P-GalactosidaseisakindofendoenzymeexistingintheE.coltcells.Itcanbereleasedfromthecellsbythepore-formingactionofcolicinEI,andcanbedetectedrapidlybyenZymatic..thodl.Colici.,areplasmid-encodedproteins,bindspecificallytoparticularreceptorsontheoutermembraneofsensitivecellsan.dactmainlythroughtwopathways'.Beca.s.theycanformporesinthemembrane,colicinshavebeenwidelyusedastoolstostudythebiologicalandphy…     

以新亚甲基蓝为电子媒介体的大肠杆菌微生物燃料电池的研究

以新亚甲基蓝(NMB) 为电子媒介体, 大肠杆菌为微生物催化剂, 设计了微生物燃料电池(MFC). 该MFC的开路电压为0.760 V, 短路电流为1.108 mA, 最大输出功率为116 mW/m2, 此时所对应的电流密度为390 mA/m2. 比较了中性红(NR)和NMB作为电子媒介体对MFC性能的影响. 实验结果表明, 以NMB为电子媒介体的MFC的开路电压比以NR为电子媒介体的MFC的开路电压低, 但其开路电压达到稳定所需要的时间更短, 而且其短路电流比后者高. 当放电电流大于114 mA/m2时, 前者比后者的输出功率高, 在负载1000 Ω放电时, 前者比后者有更好的稳定性.     

Expression of Shiga Toxin B Subunit at Cell Surface in E. coli K-12

The three parts(Stx17B, Stx27B and StxB) of Shiga toxin B subunit have been fused into a cell surface exposed loop of the LamB protein at a BamH I site between residues 153 and 154. Western blotting revealed that the three parts of Shiga toxin B subunit could be expressed as the Lamb fusion proteins in E. coli. Indirect immunofluorescence and immunoelectron microscopy analyses showed fusion proteins LamB/Stx17B and LamB/Stx27B could be expressed at cell surface in E. coli, but fusion protein LamB/StxB could not be expressed at cell surface; it was aggregated in cytoplasm and was toxic to host. This expression system provided a new way to construct an oral live vaccine against Shigella dysenteriae 1.     

大肠埃希菌高耐药率回顾性分析

目的了解和分析天津市泰达医院大肠埃希菌耐药情况,指导临床合理使用抗菌药物。方法对2010年至2012年间从临床标本中分离的859株大肠埃希菌的耐药情况进行回顾性总结分析。结果 859株大肠埃希菌对多种抗菌药物均产生不同程度的耐药性,其中对氨苄西林的耐药率达到85.0%,对碳青霉烯类抗菌药物如亚胺培南及四代头孢菌素的耐药率均低于5%。结论天津市泰达医院分离的大肠埃希菌存在严重的耐药性,耐药率达到50%的有11种,原因是滥用抗生素,应加强其耐药性监测,合理规范使用抗生素。     

大肠杆菌DNA和RNA中核苷的高效液相色谱分析

建立了用反相高效液相色谱法（RP-HPLC）测定大肠杆菌（E.coli）脱氧核糖核酸（DNA）和核糖核酸（RNA）水解产物中核苷的方法，色谱柱为Supelco Inc.c18反相柱，254nm和280nm紫外吸收波长同时检测，分析条件经选择在流速为1mL/min，流动相A（2.5%甲醇 0.01mol/L KH2PO4,PH4.6)28min，流动相B（8.0%甲醇 0.01mol/L KH2PO4，PH4.6)37min，柱温为20℃条件下65min可实现核苷的完全分离，回收率为80.19%-99.31%，相对标准偏差RSD为0.86%-2.62%，该方法具有高灵敏度、高选择性的特点，得到的结果与十分满意。     

微量量热法研究大肠杆菌对粉防己碱和粉防己总生物碱的耐药性

微量量热法研究大肠杆菌对粉防己碱和粉防己总生物碱的耐药性;粉防己碱;粉防己总生物碱;耐药性;大肠杆菌;微量量热法     

Novel indirect enzyme-linked immunosorbent assay (ELISA) method to detect Total E. coli in water environment

In order to establish ELISA (enzyme-linked immunosorbent assay) method to detect Total E. coli in water environment, E. coli multi-characters antigens in water environment were prepared according to the characters of kinds of E. coli serotypes, including antigen of whole cell, antigen of disrupted whole cell, somatic antigen, flagellar antigen and fimbrial antigen. Total E. coli polyclonal antibodies were obtained from the New Zealand rabbits immunized with these five antigens, respectively. Antibodies generated in this research are with high titers and good purity, can conjugate with antigens, specifically, stably and strongly. Indirect ELISA shows the titers of antibody of whole cell and antibody of disrupted whole cell are both over 1 × 10⁵. The cross-reactivity of the antibody is from 12 to 30% which indicate the specificity of the antibody against Total E. coli. Based on these antibodies, we established indirect ELISA method to detect Total E. coli in water environment. The matrix effects were studied and the results show that there is no significant influence by all the factors. The ELISA result shows that the detection limitation could be 10⁴ CFU (colony forming units) L⁻¹. The indirect ELISA method developed in this study is well suited for Total E. coli analysis in real water samples as a rapid screen method.     

Investigation of the Effect of Four Organic Acids in Radix Isatidis on E. coli Growth by Microcalorimetry

The inhibitory effects of four organic acids (OAs) in Radix Isatidis, a traditional Chinese medicinal herb, on Escherichia coli (E. coli) growth were investigated by microcalorimetry. The power‐time curves of E. coli growth with and without OAs were acquired, meanwhile the extent and duration of inhibitory effects on the metabolism were evaluated by growth rate constants (k₁, k₂), half inhibitory ratio (IC₅₀), maximum heat output (P_max) and peak time (t_p). The values of k₁ and k₂ of E. coli growth in the presence of the four OAs decreased with the increasing concentrations of OAs. Moreover, P_max was reduced and the value of t_p increased with increasing concentrations of the four drugs. The sequence of anti‐microbial activity of the four OAs was: syringic acid>2‐amino‐benzoic acid>salicylic acid>benzoic acid. IC₅₀ of the four OAs was respectively 56 µg/mL for syringic acid, 75 µg/mL for 2‐amino‐benzoic acid, 86 µg/mL for salicylic acid and 224 µg/mL for benzoic acid. The existence of the functional groups on phenyl ring improves the anti‐microbial activity compared to benzoic acid. The functional groups methoxyl at C(3) and C(5) improve anti‐microbial activity more strongly than the other functional groups, and the functional group amino at C(2) improve anti‐microbial activity more strongly than hydroxyl at C(2) on phenyl ring.     

Characterization of chemical constituents in Rhodiola Crenulate by high‐performance liquid chromatography coupled with Fourier‐transform ion cyclotron resonance mass spectrometer (HPLC‐FT‐ICR MS)

In this work, an approach using high‐performance liquid chromatography coupled with diode‐array detection and Fourier‐transform ion cyclotron resonance mass spectrometer (HPLC‐FT‐ICR MS) for the identification and profiling of chemical constituents in Rhodiola crenulata was developed for the first time. The chromatographic separation was achieved on an Inertsil ODS‐3 column (150 mm × 4.6 mm,3 µm) using a gradient elution program, and the detection was performed on a Bruker Solarix 7.0 T mass spectrometer equipped with electrospray ionization source in both positive and negative modes. Under the optimized conditions, a total of 48 chemical compounds, including 26 alcohols and their glycosides, 12 flavonoids and their glycosides, 5 flavanols and gallic acid derivatives, 4 organic acids and 1 cyanogenic glycoside were identified or tentatively characterized. The results indicated that the developed HPLC‐FT‐ICR MS method with ultra‐high sensitivity and resolution is suitable for identifying and characterizing the chemical constituents in R. crenulata. And it provides a helpful chemical basis for further research on R. crenulata. Copyright © 2016 John Wiley & Sons, Ltd.     

Effects of copper on dielectric properties of E. coli cells

Dielectric properties of E. coli cells before and after Cu²⁺ incubation were investigated by using the dielectric spectroscopic technique. The dielectric spectra are analyzed theoretically by means of the extended three-shell ellipsoidal model, which can reflect the complicated morphological structure of E. coli cell including the outer membrane, the periplasmic space, the inner membrane and the cytoplasm. The results showed that dielectric properties of these cellular components were changed with Cu²⁺ treatment in a time- and concentration-dependent way. The permttivity of the outer membrane increased with the incubation time and concentration of Cu²⁺, possibly because polarizability of the outer leaflet of lipopolysaccharides was affected by Cu²⁺. The conductivity of the periplasmic space decreased with the incubation time and concentration of Cu²⁺, possibly due to the damage of peptidoglycan. The decreased permittivity of the inner membrane may be caused by disturbance of the lipid bilayer structure produced by Cu²⁺ incubation. The decreased cytoplasmic conductivity may be the consequence of the leakage of K⁺ from it. The cytoplasmic permittivity decreased with Cu²⁺ treatment probably because of the leakage of its some components.     

新型金属卟啉的合成及其对大肠杆菌生长代谢的抑制作用

以5,10,15,20-四（对羟基苯基）卟啉（2）为原料,合成并表征了一系列 水溶性和非水溶性的金属卟啉。使用LKB 2277热活性监测器测定了大肠杆菌在金属 卟啉4a ～ 4f和7a ～ 7f作用下的生热曲线,得到了不同金属卟啉在不同浓度下大 肠杆菌生长代谢的生热速率常数k,最大发热功率p_(max)和最大发热功率的出现时 间t。结果发现,含有吡啶溴化盐的水溶性金属卟啉7a ～ 7f对大肠杆菌生长代谢 的抑制活性要明显大于含有酯基的金属卟啉4a ～ 4f。     

微量热法测定Vitex negundo Linn对大肠杆菌抑制作用的活性部位

开发药用植物首先必须确定其活性部位. 我们采用微量热法鉴定了一种植物Vitex negundo Linn的四种不同提取物: 正己烷提取物、氯仿提取物、乙酸乙酯提取物和甲醇提取物对大肠杆菌(E. coli)的抑制作用. 结果表明甲醇提取物对大肠杆菌生长的代谢热谱抑制作用最强. 通过计算该提取物作用下大肠杆菌的生长速率常数, 表明该提取物的抑制作用随浓度的升高而增强.     

微量热法研究头孢菌素对大肠杆菌微生物活性的影响

用微量热法测定了两种头孢菌素头孢哌酮钠(CFZ)和头孢哌酮钠舒巴坦钠(CFZ-SBT)在37 ℃时对大肠杆菌DH5α代谢作用的影响. 根据产热曲线分别获得了大肠杆菌DH5α在不同浓度的头孢哌酮钠和头孢哌酮钠舒巴坦钠作用下的生长速率常数(k)、抑制率(I)、最大产热功率(Pm)以及最大产热功率所对应的时间tm等热动力学参数. 研究结果表明, 头孢哌酮钠和头孢哌酮钠舒巴坦钠对大肠杆菌的致死量分别为0.1和0.25 μg/mL. 通过研究k, I, Pm, tm和浓度(c)间的关系发现, 舒巴坦钠的加入没有增加头孢哌酮钠对大肠杆菌DH5α的抑制作用.     

微流控芯片上大肠杆菌的电化学阻抗检测方法研究

基于细菌悬浮液的阻抗特性和微流控芯片电化学阻抗检测技术,采用所构建的微流控芯片电化学阻抗分析系统,以大肠杆菌为样本,优化了扰动振幅、缓冲溶液电导率、扫描频率和新制大肠杆菌标本静置时间等参数,对大肠杆菌标本、大肠杆菌标准合成样本进行电化学阻抗检测,建立了一种大肠杆菌快速定量检测方法.在扰动振幅500 mV、缓冲溶液电导率...     

两种细菌的毛细管电泳分离及其与药物相互作用的研究

通过对大肠杆菌与金黄色葡萄球菌的毛细管电泳行为的研究,包括对细菌样品预处理、缓冲液、检测波长以及聚合物添加剂对分离度的改进等的考察,在优化的实验条件下,实现了大肠杆菌与金黄色葡萄球菌的快速分离,从而建立一种新的细菌辅助识别与定性的补充方法。将抗菌药物阿奇霉素与金黄色葡萄球菌混合培育,发现由于阿奇霉素抑制细菌表面蛋白合成,造成与金黄色葡萄球菌作用后,细菌表面电荷密度降低,表现为阿奇霉素对金黄色葡萄球菌的电泳淌度的影响,而且培育时间与金黄色葡萄球菌的淌度线性相关。     

季铵盐型金属卟啉的合成及其对大肠杆菌生长代谢的抑制作用

以5,10,15,20-四(4′-吡啶基)卟啉为原料,合成了一系列季铵盐型金属卟啉1a,1b和2a～2c.使用LKB2277热活性监测器测定了大肠杆菌在不同浓度的金属卟啉1a,1b和2a～2c作用下的产热曲线,得到了大肠杆菌生长速率常数k,最大发热功率P_max和最大发热功率的出现时间t_p,发现季铵盐型金属卟啉2c对大肠杆菌生长代谢的抑制活性明显大于其它季铵盐型金属卟啉.     

Fabrication of an Electrochemical E. coli Biosensor in Biowells Using Bimetallic Nanoparticle‐Labelled Antibodies

An electrochemical biosensor was developed for the determination of Escherichia coli (E. coli) in water. For this purpose, silver‐gold core‐shell (Ag@Au) bioconjugates and anti‐E. coli modified PS‐microwells were designed in a sandwich‐type format in order to obtain higher sensitivity and selectivity. Ag@Au bimetallic nanoparticles were synthesized by co‐reduction method. The core‐shell formation was analyzed by using UV‐Vis spectroscopy and transmission electron microscopy. Biotin labeled anti‐E. coli antibodies were coupled with Ag@Au nanoparticles to form bioconjugates. The electrochemical immunosensor was prepared by immobilizing anti‐E. coli on polystyrene (PS)‐microwells via chemical bonding. These modified microwells were identified with X‐ray photoelectron spectroscopy and surface enhanced Raman spectroscopy. E. coli was sandwiched between Ag@Au bioconjugates and anti‐E. coli on PS‐microwells at different concentrations. The relationship between the E. coli concentration and stripping current of gold ions (Au³⁺) were investigated by square wave anodic stripping voltammetry at pencil graphite electrode. The proposed method can provide some advantages such as lower detection limit and shorter detection time. The electrochemical response for the immunosensor was linear with the concentration of the E. coli in the range of 10¹ and 10⁵ cfu/mL with a limit of detection 3 cfu/mL. The procedure maintains good sensitivity and repeatability and also offers utility in the fields of environmental monitoring and clinical diagnosis.     

Nano-ZnO微叉指电极生物传感器检测大肠杆菌

设计了一种基于纳米ZnO材料检测大肠杆菌(E.coli O157:H7)的微叉指阻抗生物传感器,利用电化学方法在氧化铟锡(ITO)叉指电极表面沉积上纳米ZnO,然后将链霉亲和素固定在纳米ZnO表面,利用生物素亲和素的高亲和性原理将大肠杆菌抗体绑定在传感器表面,完成传感器的构建。实验表明,传感器检测E.coli O157:H7线性范围为40~4×10^6cfu/mL,检出限为40 cfu/mL,传感器的特异性、重现性、实用性较好。