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1

Determination of phthalates in raw bovine milk by gas chromatography\\/time-of-flight mass spectrometry (GC\\/TOF-MS) and dietary intakes  

Microsoft Academic Search

Low levels of phthalates, including di(2-ethylhexyl) phthalate (DEHP), in raw bovine milk were determined using gas chromatography\\/time-of-flight mass spectrometry (GC\\/TOF-MS). A fast and convenient process of sample treatment combined with TOF-MS analysis (medium resolution >5000), yielded good recoveries (85–125%) and low limits of detection (<0.002 mg kg). The most commonly used phthalate, DEHP, was found in 15 out of 30

Meekyung Kim; Seon Jong Yun; Gab-Soo Chung

2009-01-01

2

[Performance of two matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) models for identification of bacteria isolated from blood culture].  

PubMed

We compared the results of two bacterial identification methods: 1) a traditional method based on phenotypic identification of the causative organism using gram-staining, culture and biochemical markers and 2) matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). A total of 111 isolates, including 107 strains of common bacteria species and 4 strains of 3 yeast species, were tested by the traditional method and MALDI-TOF MS method(VITEK MS and Micro flex LT). Data obtained using MALDI-TOF MS were classified as Level 1 and Level 2 according to the confidence level of identification results from the VITEK MS ver. 1.0 database (VITEK MS) and MALDI Biotyper ver. 2.0 database (Microflex LT). The proportions of measured samples identified as Level 1 were 98.2% with the VITEK MS database and 87.4% with the MALDI Biotyper database. The concordance rates of the traditional method were 93.7% with the VITEK MS database and 82.0% with the MALDI Biotyper database. Identification results of five strains were mismatched between the traditional method and MALDI-TOF MS. Their ribosomal RNA sequences were identical to the results obtained from MALDI-TOF MS. We concluded that the performance of VITEK MS is superior to that of the traditional method and Microflex LT. PMID:23947175

Itoh, Eisuke; Watari, Tomohisa; Azuma, Yuka; Watanabe, Naoki; Tomoda, Yutaka; Akasaka, Kazumi; Kino, Shuichi

2013-05-01

3

Rapid subtyping of Yersinia enterocolitica by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) for diagnostics and surveillance.  

PubMed

In this study, an alternative to the current traditional bioserotyping techniques was developed for subtyping Y. enterocolitica using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). The most common pathogenic bioserotypes could easily be distinguished using only a few bioserotype-specific biomarkers. However, biochemical methods should still be used to distinguish biotype 1A from 1B. PMID:24048527

Rizzardi, Kristina; Wahab, Tara; Jernberg, Cecilia

2013-12-01

4

Development of Decision Tree Software and Protein Profiling using Surface Enhanced Laser Desorption\\/Ionization - Time of Flight - Mass Spectrometry (SELDI-TOF-MS) in Papillary Thyroid Cancer  

Microsoft Academic Search

Purpose: The aim of this study was to develop a bioinformatics software and to test it in serum samples of papillary thyroid cancer using mass spectrometry (SELDI-TOF-MS). Materials and Methods: Development of 'Protein analysis' software performing decision tree analysis was done by customizing C4.5. Sixty-one serum samples from 27 papillary thyroid cancer, 17 autoimmune thyroiditis, 17 controls were applied to

Joon-Kee Yoon; Jun Lee; Bok-Nam Park; Seok Nam Yoon

5

Feasibility of matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS) networking in university hospitals in Brussels.  

PubMed

The mutualisation of analytical platforms might be used to address rising healthcare costs. Our study aimed to evaluate the feasibility of networking a unique matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS) system for common use in several university hospitals in Brussels, Belgium. During a one-month period, 1,055 successive bacterial isolates from the Brugmann University Hospital were identified on-site using conventional techniques; these same isolates were also identified using a MALDI-TOF MS system at the Porte de Hal Laboratory by sending target plates and identification projects via transportation and the INFECTIO_MALDI software (Infopartner, Nancy, France), respectively. The occurrence of transmission problems (<2 %) and human errors (<1 %) suggested that the system was sufficiently robust to be implemented in a network. With a median time-to-identification of 5 h and 11 min (78 min, min-max: 154-547), MALDI-TOF MS networking always provided a faster identification result than conventional techniques, except when chromogenic culture media and oxidase tests were used (p?TOF MS networking could lead to substantial annual cost savings. MALDI-TOF MS networking presents many advantages, and few conventional techniques (optochin and oxidase tests) are required to ensure the same quality in patient care from the distant laboratory. Nevertheless, such networking should not be considered unless there is a reorganisation of workflow, efficient communication between teams, qualified technologists and a reliable IT department and helpdesk to manage potential connectivity problems. PMID:24197439

Martiny, D; Cremagnani, P; Gaillard, A; Miendje Deyi, V Y; Mascart, G; Ebraert, A; Attalibi, S; Dediste, A; Vandenberg, O

2014-05-01

6

Subtype determination of Blastocystis isolates by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS).  

PubMed

The pathogenic role of the enteric parasite Blastocystis remains controversial. Recent studies have suggested that various subtypes (STs) found in human samples could be correlated to the presence or absence and variability of clinical manifestations, and that STs can differ with respect to drug sensitivity. Polymerase chain reaction (PCR) techniques used to determine these STs are expensive and are usually restricted to research laboratory settings. This study evaluates the potential application of the inexpensive matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS) technique to discriminate Blastocystis STs. A database of parasitic protein signatures was constructed for five Blastocystis STs, and the reference spectra were challenged with those from 19 axenic cultures of ST1, ST2, ST3, ST4 and ST8 and those from nine xenic liquid cultures of ST3 and ST4. Samples from axenic cultures were prepared using standard formic acid extraction and direct deposition procedures. The reference spectra revealed five distinct spectral profiles, and the database library allowed for discrimination between all of the cultures with reliability indices ranging from 2.038 to greater than 2.8 when an extraction was performed. The direct deposition procedure resulted in greater variability in the discrimination and direct MALDI-TOF MS identification from xenic liquid cultures was effective in 3 out of 9 samples. MALDI-TOF MS proved to be an effective technology for efficiently discriminating Blastocystis STs in axenic cultures. PMID:24078024

Martiny, D; Bart, A; Vandenberg, O; Verhaar, N; Wentink-Bonnema, E; Moens, C; van Gool, T

2014-04-01

7

A direct and simple method of coupling matrix-assisted laser desorption and ionization time-of-flight mass spectrometry (MALDI-TOF MS) to thin-layer chromatography (TLC) for the analysis of phospholipids from egg yolk  

Microsoft Academic Search

Although the most important application of matrix-assisted laser desorption and ionization time-of-flight mass spectrometry\\u000a (MALDI-TOF MS) is “proteomics,” there is growing evidence that this soft ionization method is also useful for phospholipid\\u000a (PL) analysis. Although all PLs are detectable by MALDI-TOF MS, some lipid classes, particularly those with quaternary amines\\u000a such as phosphatidylcholines (PCs), are more sensitively detected than others,

Beate Fuchs; Jürgen Schiller; Rosmarie Süß; Martin Schürenberg; Detlev Suckau

2007-01-01

8

Differences in protein profiles of the isolates of Entamoeba histolytica and E. dispar by surface-enhanced laser desorption ionization time-of-flight mass spectrometry (SELDI-TOF MS) ProteinChip assays  

Microsoft Academic Search

Surface-enhanced laser desorption ionization time of flight mass spectrometry (SELDI-TOF MS) ProteinChip assays with weak\\u000a cationic exchange chips were used for protein profiling of different isolates of Entamoeba histolytica and E. dispar. When SELDI-TOF MS spectra of cell lysates from E. histolytica strain HM-1:IMSS were compared with those from four other laboratory strains (200:NIH, HK-9, DKB, and SAW755CR) grown under

Asao Makioka; Masahiro Kumagai; Seiki Kobayashi; Tsutomu Takeuchi

2007-01-01

9

Serum Amyloid Beta Peptides in Patients with Dementia and Age-Matched Non-Demented Controls as Detected by Surface-Enhanced Laser Desorption Ionisation-Time of Flight Mass Spectrometry (SELDI-TOF MS)  

Microsoft Academic Search

Background: By using surface enhanced laser desorption\\/ionisation- time of flight mass spectrometry (SELDI- TOF MS) an amyloid ß (Aß) profile was shown in cerebrospinal fluid (CSF) of patients with dementia. Objective: To investigate the A? -profile in serum with SELDI-TOF MS, to evaluate if this profile resembles CSF profiles and to investigate the correlation between intensity of A? -peptide-peaks in

Suzanne V. Frankfort; Jos P. C. M. van Campen; Linda R. Tulner; Jos H. Beijnen

2008-01-01

10

Determination of phthalates in raw bovine milk by gas chromatography/time-of-flight mass spectrometry (GC/TOF-MS) and dietary intakes.  

PubMed

Low levels of phthalates, including di(2-ethylhexyl) phthalate (DEHP), in raw bovine milk were determined using gas chromatography/time-of-flight mass spectrometry (GC/TOF-MS). A fast and convenient process of sample treatment combined with TOF-MS analysis (medium resolution >5000), yielded good recoveries (85-125%) and low limits of detection (<0.002 mg kg(-1)). The most commonly used phthalate, DEHP, was found in 15 out of 30 samples monitored in this study. DEHP concentrations in raw milk ranged from not detected to 0.154 mg kg(-1), and the mean concentration was 0.057 mg kg(-1). The dietary intake of DEHP was about 0.004 mg kg(-1) body weight day(-1) if a child (24 months, 13 kg body weight) drinks 1 L day(-1) of milk that contains the mean concentration of DEHP found in raw milk. The estimated dietary intake corresponded to 8% of the European Union tolerable daily intake (TDI) of 0.05 mg kg(-1) body weight day(-1). Dimethyl phthalate (DMP) and di-n-butyl phthalate (DBP) were found from two and 20 samples, respectively, at low levels. Diethyl phthalate (DEP), butylbenzyl phthalate (BBP), and di-n-octyl phthalate (DnOP) were not found in any of the samples. PMID:19680881

Kim, Meekyung; Yun, Seon Jong; Chung, Gab-Soo

2009-01-01

11

Rapid Identification of Bacillus anthracis Spores in Suspicious Powder Samples by Using Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS)  

PubMed Central

Rapid and reliable identification of Bacillus anthracis spores in suspicious powders is important to mitigate the safety risks and economic burdens associated with such incidents. The aim of this study was to develop and validate a rapid and reliable laboratory-based matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) analysis method for identifying B. anthracis spores in suspicious powder samples. A reference library containing 22 different Bacillus sp. strains or hoax materials was constructed and coupled with a novel classification algorithm and standardized processing protocol for various powder samples. The method's limit of B. anthracis detection was determined to be 2.5 × 106 spores, equivalent to a 55-?g sample size of the crudest B. anthracis-containing powder discovered during the 2001 Amerithrax incidents. The end-to-end analysis method was able to successfully discriminate among samples containing B. anthracis spores, closely related Bacillus sp. spores, and commonly encountered hoax materials. No false-positive or -negative classifications of B. anthracis spores were observed, even when the analysis method was challenged with a wide range of other bacterial agents. The robustness of the method was demonstrated by analyzing samples (i) at an external facility using a different MALDI-TOF MS instrument, (ii) using an untrained operator, and (iii) using mixtures of Bacillus sp. spores and hoax materials. Taken together, the observed performance of the analysis method developed demonstrates its potential applicability as a rapid, specific, sensitive, robust, and cost-effective laboratory-based analysis tool for resolving incidents involving suspicious powders in less than 30 min.

van der Laaken, Anton L.; Blatny, Janet Martha; Paauw, Armand

2013-01-01

12

Multi-residue analysis method for analysis of pharmaceuticals using liquid chromatography-time of flight/mass spectrometry (LC-TOF/MS) in water sample  

NASA Astrophysics Data System (ADS)

In this work, a developed method using solid - phase extraction (SPE) followed by liquid chromatography - time of flight mass spectrometry (LC-ESI-TOF/MS) was developed and validated for quantification and confirmation of eleven pharmaceuticals with different therapeutic classes in water samples, Malaysia. These compounds are caffeine (CAF), prazosin (PRZ), enalapril (ENL), carbamazepine (CBZ), nifedipine (NFD), levonorgestrel (LNG), simvastatin (SMV), hydrochlorothiazide (HYD), gliclazide (GLIC), diclofenac-Na (DIC-Na) and mefenamic acid (MEF). LC was performed on a Dionex Ultimate 3000/LC 09115047 (USA) system. Chromatography was performed on a Thermo Scientific C18 (250 mm × 2.1 mm, i.d.: 5?m) column. Several parameters were optimised such as; mobile phase, gradient elution, collision energy and solvent elution for extraction of compounds from water. The recoveries obtained ranged from 30-148 % in river water. Five pharmaceutical compounds were detected in the surface water samples: caffeine, prazosin, enalpril, diclofenac-Na and mefenamic acid. The developed method is precise and accepted recoveries were got. In addition, this method is suitable to identify and quantify trace concentrations of pharmaceuticals in surface water.

Al-Qaim, Fouad Fadhil; Abdullah, Md Pauzi; Othman, Mohamed Rozali

2013-11-01

13

Adduct formation of Thimerosal with human and rat hemoglobin: a study using liquid chromatography coupled to electrospray time-of-flight mass spectrometry (LC/ESI-TOF-MS).  

PubMed

Thimerosal (THI) is used as a preservative in many vaccines throughout the world. Ethylmercury (EtHg(+)), released from THI in aqueous media, has a high affinity to thiol functions of proteins. In blood, hemoglobin is a likely target protein because of its high abundance and its several free thiol functions. In comparison to hemoglobin of human origin, hemoglobin of rats exhibits almost twice as many free thiol groups, which might lead to different binding behavior and therefore a limited comparability between the situation in man and in rats, which are frequently used as models for mercury species toxicity investigations. Thus, the adduct formation of EtHg(+) with hemoglobin of humans and rats was compared under simulated physiological conditions by using gradient reversed-phase liquid chromatography (LC) with electrospray time-of-flight mass spectrometry (ESI-TOF-MS) detection. The binding stoichiometry correlated with the number of free thiols in the ?- and ?-chain of hemoglobin. The use of rats to verify the safety of additives in vaccines like Thimerosal is therefore doubtful and should be reevaluated. PMID:21706086

Janzen, Rasmus; Schwarzer, Miriam; Sperling, Michael; Vogel, Martin; Schwerdtle, Tanja; Karst, Uwe

2011-08-01

14

Technical Note: Performance of Chemical Ionization Reaction Time-of-Flight Mass Spectrometry (CIR-TOF-MS) for the measurement of atmospherically significant oxygenated volatile organic compounds  

Microsoft Academic Search

The performance of a new chemical ionization re- action time-of-flight mass spectrometer (CIR-TOF-MS) util- ising the environment chamber SAPHIR (Simulation of At- mospheric Photochemistry In a large Reaction Chamber- Forschungzentrum Julich, Germany) is described. The work took place as part of the ACCENT (Atmospheric Composi- tion and Change the European NeTwork for excellence) sup- ported oxygenated volatile organic compound (OVOC)

K. P. Wyche; R. S. Blake; A. M. Ellis; P. S. Monks; T. Brauers; R. Koppmann; E. C. Apel

2007-01-01

15

Performance of Chemical Ionization Reaction Time-of-Flight Mass Spectrometry (CIR-TOF-MS) for the measurement of atmospherically significant oxygenated volatile organic compounds  

Microsoft Academic Search

The performance of a new chemical ionization reaction time-of-flight mass spectrometer (CIR-TOF-MS) utilising the environment chamber SAPHIR (Simulation of Atmospheric Photochemistry In a large Reaction Chamber - Forschungzentrum Jülich, Germany) is described. The work took place as part of the ACCENT (Atmospheric Composition and Change the European NeTwork for excellence) supported oxygenated volatile organic compound (OVOC) measurement intercomparison during January

K. P. Wyche; R. S. Blake; A. M. Ellis; P. S. Monks; T. Brauers; R. Koppmann; E. Apel

2006-01-01

16

Technical Note: Performance of Chemical Ionization Reaction Time-of-Flight Mass Spectrometry (CIR-TOF-MS) for the measurement of atmospherically significant oxygenated volatile organic compounds  

Microsoft Academic Search

The performance of a new chemical ionization reaction time-of-flight mass spectrometer (CIR-TOF-MS) utilising the environment chamber SAPHIR (Simulation of Atmospheric Photochemistry In a large Reaction Chamber- Forschungzentrum Jülich, Germany) is described. The work took place as part of the ACCENT (Atmospheric Composition and Change the European NeTwork for excellence) supported oxygenated volatile organic compound (OVOC) measurement intercomparison during January 2005.

K. P. Wyche; R. S. Blake; A. M. Ellis; P. S. Monks; T. Brauers; R. Koppmann; E. C. Apel

2007-01-01

17

Detection of aqueous phase chemical warfare agent degradation products by negative mode ion mobility time-of-flight mass spectrometry [IM(tof)MS  

Microsoft Academic Search

The use of negative ion monitoring mode with an atmospheric pressure ion mobility orthogonal reflector time-of-flight mass\\u000a spectrometer [IM(tof)MS] to detect chemical warfare agent (CWA) degradation products from aqueous phase samples has been determined.\\u000a Aqueous phase sampling used a traditional electrospray ionization (ESI) source for sample introduction and ionization. Certified\\u000a reference materials (CRM) of CWA degradation products for the detection

Wes E. Steiner; Charles S. Harden; Feng Hong; Steve J. Klopsch; Vincent M. McHugh

2006-01-01

18

Elucidation of riverine and lacustrine dissolved organic matter (DOM) composition using comprehensive GC×GC time-of-flight mass spectrometry (GC×GC-TOF-MS)  

NASA Astrophysics Data System (ADS)

Rivers and streams play a key role in mediating the transfer of organic carbon (both particulate and dissolved) from terrestrial to aquatic settings. Dissolved organic carbon represents the majority of the carbon pool in low alkalinity riverine and lacustrine waters, and its composition plays important roles, including affecting water clarity and stimulating heterotrophic productivity, which influences its rate of reconversion to CO2. Yet, the chemical complexity and heterogeneity of this reservoir have limited structural elucidation to primarily describing common bulk-level characteristics. Seasonal SPE-DOM samples from the Upper Truckee River, Lake Tahoe, and two surrounding lakes, as well as SPE-DOM isolated from two dissimilar California rivers, were first characterized using ?13C, ?15N, 1H-NMR, and then subjected to CuO oxidation followed by TMS derivatization and were analyzed using comprehensive GC×GC time-of-flight mass spectrometry (GC×GC-TOF-MS). Thousands of peaks were identified per sample. Simultaneous, orthogonal separation of components in two dimensions (on the basis of volatility and polarity) allowed for the identification of oxidation mixture components by both their MS spectra and, when MS spectra alone were insufficient for structural assignment and standards were absent, by the observed trajectories of homologues compound series assumed in 2-D retention-time space. Several homologous compound series were observed, including mid-to-long chain fatty acids, keto (?-1) fatty acids, (?, ?)-dioic acids, and the resolution and identification of closely related isomers, such as the benzene di-, and tricarboxylic acids, were also facilitated by this method. Furthermore, in mixed samples containing two or more end-members, such as in lake DOM samples characterized by mixed terrestrial and algal OM sources, the intensity of the phenolic elution space, which includes the lignin phenols and lignin phenolic dimers, correlates with ancillary measurements indicative of terrestrial OM loading, such as increased 1H-NMR resonance intensities for methoxy and aromatic-linked hydrogens and lower ?13C values more consistent with C3 plant versus algal sources.igure 1: Oxidized and derivatized SPE-DOM isolated from the Upper Truckee River, South Lake Tahoe, CA, and visualized in two dimensions.

Ball, G. I.; Goldberg, S. J.; Aluwihare, L. I.

2012-12-01

19

Rapid identification of betacyanins from Amaranthus tricolor, Gomphrena globosa, and Hylocereus polyrhizus by matrix-assisted laser desorption/ionization quadrupole ion trap time-of-flight mass spectrometry (MALDI-QIT-TOF MS).  

PubMed

Natural betacyanins have attracted great attention as food colorants and potential antioxidants. Matrix-assisted laser desorption/ionization quadrupole ion trap time-of-flight mass spectrometry (MALDI-QIT-TOF MS) is a new and powerful technique for the identification of low molecular weight compounds. This study is the first to employ MALDI-QIT-TOF MS to rapidly identify, within a few minutes, a great number of betacyanins in crude extracts from Amaranthus tricolor seedlings, Gomphrena globosa flowers, and Hylocereus polyrhizus fruits. The fresh crude extract samples without any purification were directly used for MALDI-QIT-TOF MS analysis with 2,5-dihydroxybenzoic acid as a matrix. The MS2 and MS3 spectrometric data acquired could provide important characteristic information for structural elucidation of the betacyanins. Fourteen free and acylated betacyanins, belonging to amaranthin-type, betanin-type, and gomphrenin-type betacyanins, respectively, were identified. However, the related isomers should be differentiated with the aid of HPLC. PMID:16939305

Cai, Yi-Zhong; Xing, Jie; Sun, Mei; Corke, Harold

2006-09-01

20

Sensomics analysis of key hazelnut odorants (Corylus avellana L. 'Tonda Gentile') using comprehensive two-dimensional gas chromatography in combination with time-of-flight mass spectrometry (GC×GC-TOF-MS).  

PubMed

Comprehensive two-dimensional gas chromatography-mass spectrometry (GC×GC-MS) has been used a few times to identify and quantitate single aroma-active compounds, but the capability of this technique to monitor a complete set of key odorants evoking the aroma of a given food in one run has not been exploited so far. A fast, multiodorant analysis using GC×GC-TOF-MS in combination with stable isotope dilution assays (SIDA) was developed to quantitate the entire set of aroma compounds, the sensometabolome, of raw and roasted hazelnuts ( Corylus avellana L. 'Tonda Gentile') previously established by GC-olfactometry. The capability of the method to evaluate the aroma contribution of each sensometabolite was evaluated by introducing a new term, the limit of odor activity value (LOAV), indicating whether a given aroma compound can be determined down to an odor activity value (OAV) of 1 (odor activity value = ratio of concentration to odor threshold). The advantage of the new method was proven by comparing the performance parameters with a traditional one-dimensional approach using GC-ion trap mass-spectrometry (GC-IT-MS). The results showed that the detector linearity and sensitivity of GC×GC-TOF-MS was on average higher by a factor of 10 compared to GC-IT-MS, thus enabling the quantitation of the aroma relevant amounts of 22 key odorants of hazelnuts in one run of the 30 aroma-active compounds. Seven novel isotopically labeled internal standards were synthesized to meet the analytical requirements defined by electron impact ionization in TOF-MS, that is, to keep the label. On the basis of the quantitative results obtained, it was possible to closely mimic the aroma of raw and roasted 'Tonda Gentile' hazelnuts by preparing an aroma recombinate containing the key odorants at their natural concentrations occurring in the nuts. PMID:23663170

Kiefl, Johannes; Pollner, Gwendola; Schieberle, Peter

2013-06-01

21

Laser ablation time-of-flight mass spectrometry (LA-TOF-MS) of “nitrogen doped diamond-like carbon (DLN) nano-layers”  

NASA Astrophysics Data System (ADS)

Nitrogen-doped diamond-like carbon (DLC) layers (a-C:H:N, N-DLC or DLN) were prepared by the plasma-enhanced chemical vapor deposition (PECVD) technique, using a RF capacitive discharge (13.56 MHz), at low pressures (20 Pa), produced from a mixture of methane, nitrogen and hexamethyldisiloxane (HMDSO), deposited on single-crystalline silicon wafers placed on steel samples. The films, of differing deposition times, were subjected to laser ablation time-of-flight (LA-TOF) mass spectrometric measurements, using different commercial instrumentation to characterize their structures. The analysis of mass spectra was made and the following positively singly charged species were detected and identified: Cn+ (n=4 30), Sin+ (n=2, 3), SinH+ (n=2, 3), SiOK+, Si3H4+, Si2N+, Si2NH2+, and Si3C+. The later three species could reflect the presence of nitrogen silica and carbon silica chemical bonds in the structure of the DLN layer. The stoichiometry of all species was confirmed by isotopic pattern simulation. In the negative detection mode, the Cn- (n=2 12) clusters were observed. The findings are discussed in the light of the current research concerning analysis of the DLN thin layers and it is concluded that namely Si2N+, Si2NH2+ and Si3C+ species are reflecting the chemical structure of the DLN layer. LA-TOF-MS was found useful supplementary method for the characterization of DLN nano-layers.

Buršíková, Vilma; ?ehulka, Pavel; Chmelík, Josef; Alberti, Milan; Špalt, Zbyn?k; Jan?a, Jan; Havel, Josef

2007-05-01

22

Analysis of the chemical composition of the essential oil of Polygonum minus Huds. using two-dimensional gas chromatography-time-of-flight mass spectrometry (GC-TOF MS).  

PubMed

The essential oil in leaves of Polygonum minus Huds., a local aromatic plant, were identified by a pipeline of gas chromatography (GC) techniques coupled with mass-spectrometry (MS), flame ionization detector (FID) and two dimensional gas chromatography time of flight mass spectrometry (GC x GC-TOF MS). A total of 48 compounds with a good match and high probability values were identified using this technique. Meanwhile, 42 compounds were successfully identified in this study using GC-MS, a significantly larger number than in previous studies. GC-FID was used in determining the retention indices of chemical components in P. minus essential oil. The result also showed the efficiency and reliability were greatly improved when chemometric methods and retention indices were used in identification and quantification of chemical components in plant essential oil. PMID:20944520

Baharum, Syarul Nataqain; Bunawan, Hamidun; Ghani, Ma'aruf Abd; Mustapha, Wan Aida Wan; Noor, Normah Mohd

2010-01-01

23

Discrimination of pre- and post-treatment breast cancer serum using SELDI-TOF MS (surfaced-enhanced laser desorption\\/ionization-time of flight mass spectrometry)  

Microsoft Academic Search

Introduction: Serum protein profiles generated and analyzed by SELDI-TOF MS can distinguish women with breast cancer from normal healthy women. Our objective was to determine if the breast cancer protein profile reverts to a normal pattern after treatment.Methods: Following IRB approval, serum samples were obtained pre and 6 months post-treatment from women newly diagnosed with breast cancer (Ca) and normal

Stephen M. Becker; Betsy Gregory; O. John Semmes; Richard Drake; Christine Laronga

2004-01-01

24

Combined use of ESI–QqTOF-MS and ESI–QqTOF-MS\\/MS with mass-spectral library search for qualitative analysis of drugs  

Microsoft Academic Search

The potential of the combined use of ESI–QqTOF-MS and ESI–QqTOF-MS\\/MS with mass-spectral library search for the identification\\u000a of therapeutic and illicit drugs has been evaluated. Reserpine was used for standardizing experimental conditions and for\\u000a characterization of the performance of the applied mass spectrometric system. Experiments revealed that because of the mass\\u000a accuracy, the stability of calibration, and the reproducibility of

Marion Pavlic; Kathrin Libiseller; Herbert Oberacher

2006-01-01

25

Source-Identifying Biomarker Ions between Environmental and Clinical Burkholderia pseudomallei Using Whole-Cell Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS)  

PubMed Central

Burkholderia pseudomallei is the causative agent of melioidosis, which is an endemic disease in Northeast Thailand and Northern Australia. Environmental reservoirs, including wet soils and muddy water, serve as the major sources for contributing bacterial infection to both humans and animals. The whole-cell matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (whole-cell MALDI-TOF MS) has recently been applied as a rapid, accurate, and high-throughput tool for clinical diagnosis and microbiological research. In this present study, we employed a whole-cell MALDI-TOF MS approach for assessing its potency in clustering a total of 11 different B. pseudomallei isolates (consisting of 5 environmental and 6 clinical isolates) with respect to their origins and to further investigate the source-identifying biomarker ions belonging to each bacterial group. The cluster analysis demonstrated that six out of eleven isolates were grouped correctly to their sources. Our results revealed a total of ten source-identifying biomarker ions, which exhibited statistically significant differences in peak intensity between average environmental and clinical mass spectra using ClinProTools software. Six out of ten mass ions were assigned as environmental-identifying biomarker ions (EIBIs), including, m/z 4,056, 4,214, 5,814, 7,545, 7,895, and 8,112, whereas the remaining four mass ions were defined as clinical-identifying biomarker ions (CIBIs) consisting of m/z 3,658, 6,322, 7,035, and 7,984. Hence, our findings represented, for the first time, the source-specific biomarkers of environmental and clinical B. pseudomallei.

Srisanga, Kitima; Roytrakul, Sittiruk; Tungpradabkul, Sumalee

2014-01-01

26

Detection of carbapenemase activities of Bacteroides fragilis strains with matrix-assisted laser desorption ionization--time of flight mass spectrometry (MALDI-TOF MS).  

PubMed

Today resistance against carbapenems is considered an emerging problem in Bacteroides fragilis. Carbapenemase activities produced by aerobic bacteria have been detected by looking at hydrolysis of carbapenems with MALDI-TOF MS, but this technique was never used for anaerobic bacteria. We have developed a protocol for detection and verification of carbapenemase production in B. fragilis within 2.5 h. Twenty-eight strains of B. fragilis were tested. Of the sixteen cfiA-positive strains all showed hydrolysis of ertapenem, whereas the twelve cfiA-negative strains showed no hydrolysis. Ertapenem hydrolysis could be inhibited with 2,6-Pyridinecarboxylic acid (DPA) in all cfiA-positive strains, verifying the presence of the metallo-beta-lactamase. Here we show a rapid way to detect carbapenemase activities of B. fragilis strains. PMID:24480431

Johansson, Asa; Nagy, Elisabeth; Sóki, József

2014-04-01

27

Metabolites profiling of Pulsatilla saponin D in rat by ultra performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC/Q-TOF-MS/MS).  

PubMed

Pulsatilla saponin D, an antitumor substance isolated from traditional Chinese herbal medicine Pulsatilla chinensis (Bge.) Regel, is a promising candidate for new drug development. The purpose of the present study is to establish a simple and practical strategy for the metabolite profiling of Pulsatilla saponin D in vivo. A total of 18 metabolites were identified in rat plasma, urine and feces samples based on MS and MS/MS data by using ESI-Q-TOF-MS/MS, and eight of them (M11-M18) were reported for the first time. The results indicated that deglycosylation, dehydrogenation, hydroxylation and sulfation were the major metabolic transformations of Pulsatilla saponin D in vivo. This study has improved our understanding of the metabolic fate of Pulsatilla saponin D in vivo, and the information gained from the current study is relevant to the pharmacological activity of Pulsatilla saponin D. PMID:24831737

Ouyang, Hui; Zhou, Maofu; Guo, Yicheng; He, Mingzhen; Huang, Hesong; Ye, Xide; Feng, Yulin; Zhou, Xin; Yang, Shilin

2014-07-01

28

QUANTIFICATION OF UNRESOLVED COMPLEX MIXTURE (UCM) HYDROCARBONS USING MULTIDIMENSIONAL GAS CHROMATOGRAPHY TIME-OF-FLIGHT MASS SPECTROMETRY (GCXGC-TOF-MS)  

Microsoft Academic Search

Weathered petroleum hydrocarbon residues are characterised by 'humps' or unresolved complex mixtures (UCMs) of hydrocarbons when analysed using traditional gas chromatography. We have previously shown that comprehensive two-dimensional gas chromatography - time of flight-mass spectrometry (GCxGC-ToF-MS) can be used to resolve and identify hydrocarbons in UCMs accumulated by mussels (Booth et al., 2006). Tissue extracts from mussels (Mytilus edulis) collected

Andy M. BOOTH; Alan SCARLETT; Steven J. ROWLAND; Alastair C. LEWIS; C. Anthony LEWIS

29

Eddy covariance emission and deposition flux measurements using proton transfer reaction - time of flight - mass spectrometry (PTR-TOF-MS): comparison with PTR-MS measured vertical gradients and fluxes  

NASA Astrophysics Data System (ADS)

During summer 2010, a proton transfer reaction - time of flight - mass spectrometer (PTR-TOF-MS) and a quadrupole proton transfer reaction mass spectrometer (PTR-MS) were deployed simultaneously for one month in an orange orchard in the Central Valley of California to collect continuous data suitable for eddy covariance (EC) flux calculations. The high time resolution (5 Hz) and high mass resolution (up to 5000 m/?m) data from the PTR-TOF-MS provided the basis for calculating the concentration and flux for a wide range of volatile organic compounds (VOC). Throughout the campaign, 664 mass peaks were detected in mass-to-charge ratios between 10 and 1278. Here we present PTR-TOF-MS EC fluxes of the 27 ion species for which the vertical gradient was simultaneously measured by PTR-MS. These EC flux data were validated through spectral analysis (i.e., co-spectrum, normalized co-spectrum, and ogive). Based on inter-comparison of the two PTR instruments, no significant instrumental biases were found in either mixing ratios or fluxes, and the data showed agreement within 5% on average for methanol and acetone. For the measured biogenic volatile organic compounds (BVOC), the EC fluxes from PTR-TOF-MS were in agreement with the qualitatively inferred flux directions from vertical gradient measurements by PTR-MS. For the 27 selected ion species reported here, the PTR-TOF-MS measured total (24 h) mean net flux of 299 ?g C m-2 h-1. The dominant BVOC emissions from this site were monoterpenes (m/z 81.070 + m/z 137.131 + m/z 95.086, 34%, 102 ?g C m-2 h-1) and methanol (m/z 33.032, 18%, 72 ?g C m-2 h-1). The next largest fluxes were detected at the following masses (attribution in parenthesis): m/z 59.048 (mostly acetone, 12.2%, 36.5 ?g C m-2 h-1), m/z 61.027 (mostly acetic acid, 11.9%, 35.7 ?g C m-2 h-1), m/z 93.069 (para-cymene + toluene, 4.1%, 12.2 ?g C m-2 h-1), m/z 45.033 (acetaldehyde, 3.8%, 11.5 ?g C m-2 h-1), m/z 71.048 (methylvinylketone + methacrolein, 2.4%, 7.1 ?g C m-2 h-1), and m/z 69.071 (isoprene + 2-methyl-3-butene-2-ol, 1.8%, 5.3 ?g C m-2 h-1). Low levels of emission and/or deposition (<1.6% for each, 5.8% in total flux) were observed for the additional reported masses. Overall, our results show that EC flux measurements using PTR-TOF-MS is a powerful new tool for characterizing the biosphere-atmosphere exchange including both emission and deposition for a large range of BVOC and their oxidation products.

Park, J.-H.; Goldstein, A. H.; Timkovsky, J.; Fares, S.; Weber, R.; Karlik, J.; Holzinger, R.

2013-02-01

30

A Silicon Nanomembrane Detector for Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) of Large Proteins  

PubMed Central

We describe a MALDI-TOF ion detector based on freestanding silicon nanomembrane technology. The detector is tested in a commercial MALDI-TOF mass spectrometer with equimolar mixtures of proteins. The operating principle of the nanomembrane detector is based on phonon-assisted field emission from these silicon nanomembranes, in which impinging ion packets excite electrons in the nanomembrane to higher energy states. Thereby the electrons can overcome the vacuum barrier and escape from the surface of the nanomembrane via field emission. Ion detection is demonstrated of apomyoglobin (16,952 Da), aldolase (39,212 Da), bovine serum albumin (66,430 Da), and their equimolar mixtures. In addition to the three intact ions, a large number of fragment ions are also revealed by the silicon nanomembrane detector, which are not observable with conventional detectors.

Park, Jonghoo; Blick, Robert H.

2013-01-01

31

A silicon nanomembrane detector for matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) of large proteins.  

PubMed

We describe a MALDI-TOF ion detector based on freestanding silicon nanomembrane technology. The detector is tested in a commercial MALDI-TOF mass spectrometer with equimolar mixtures of proteins. The operating principle of the nanomembrane detector is based on phonon-assisted field emission from these silicon nanomembranes, in which impinging ion packets excite electrons in the nanomembrane to higher energy states. Thereby the electrons can overcome the vacuum barrier and escape from the surface of the nanomembrane via field emission. Ion detection is demonstrated of apomyoglobin (16,952 Da), aldolase (39,212 Da), bovine serum albumin (66,430 Da), and their equimolar mixtures. In addition to the three intact ions, a large number of fragment ions are also revealed by the silicon nanomembrane detector, which are not observable with conventional detectors. PMID:24152929

Park, Jonghoo; Blick, Robert H

2013-01-01

32

[Metabolite fingerprint and biomarkers identification of rat urine after dosed with ginsenoside Rg3 based on ultra high performance liquid chromatography/time-of-flight mass spectrometry (UPLC/TOF-MS)].  

PubMed

Porous particles of 1.7 microm was employed for ultra high performance liquid chromatography (UPLC), resulting in higher peak capacity, greater resolution and increased sensitivity in comparison with high performance liquid chromatography (HPLC). Time-of-flight mass spectrometer (TOF-MS) with a lockmass interface was used for the structure identification through exact mass and MS/MS experiment. The hyphenation of these two technologies made it a suitable platform for analysis of complex samples and identification of unknown compounds. Ginsenoside Rg3 has been considered as the major active component of Panax ginseng. Effect of the administration of a single dose of the Ginsenoside Rg3 to male Sprague Dawley rats on the urinary metabolite profiles of a range of endogenous metabolites had been investigated using UPLC/TOF-MS. Urine samples were collected from both dosed and control animals. Analysis of these samples revealed marked changes in the pattern of endogenous metabolites due to the effect of Ginsenoside Rg3. Significant disturbances in the urinary metabolite were observed in the first day after dose. Endogenous metabolites with significant up-regulation identified by accurate mass and MS/MS were xanthurenic acid, and kynurenic acid. PMID:16827300

Wang, Jiangshan; Zhao, Xinjie; Zheng, Yufang; Kong, Hongwei; Lu, Guo; Cai, Zongwei; Xu, Guowang

2006-01-01

33

Studies on the chemical transformation of 20(S)-protopanaxatriol (PPT)-type ginsenosides R(e), R(g2), and R(f) using rapid resolution liquid chromatography coupled with quadruple-time-of-flight mass spectrometry (RRLC-Q-TOF-MS).  

PubMed

A rapid resolution liquid chromatography coupled with quadruple-time-of-flight mass spectrometry (RRLC-Q-TOF-MS) method was developed for analysis of chemical transformation of 20(S)-protopanaxatriol (PPT)-type ginsenosides Re, Rg2, and Rf in acidic conditions. The transformation products were identified by comparing the retention time of the standard compounds, the accurate mass measurement, and the fragment ions obtained from RRLC-Q-TOF-tandem mass spectrometry (MS/MS) analyses. The specific product ions of aglycone PPT (m/z 475), C-24- and C-25-hydrated PPT (m/z 493), and ?20(21) or ?20(22) dehydration PPT (m/z 457) by MS/MS were discussed for structural characterization. Experiments demonstrated that chemical transformation mechanisms of 20(S)-PPT-type ginsenosides in acidic conditions include hydrolysis of saccharide substitution, ?20(21) or ?20(22) dehydration, and hydration addition reactions at C-24 and C-25. The chemical transformation pathway for 20(S)-PPT-type ginsenosides was summarized. The developed RRLC-Q-TOF-MS method was also applied for comparative analysis of 20(S)-PPT ginsenoside and related chemical transformation products in ginseng products. PMID:22991995

Wu, Wei; Qin, Qiujie; Guo, Yingying; Sun, Jinghui; Liu, Shuying

2012-10-10

34

Matrix-assisted laser desorption/ionization mass spectrometry (MALDI TOF MS) study of Huperzine A, a natural anti-Alzheimer's disease product, its derivatization and its detection by highly sensitive laser induced fluorescence (LIF).  

PubMed

Huperzine A, a reversible acetylcholinesterase inhibitor for the treatment of Alzheimer disease (HupA), was studied using an (MALDI TOF MS) instrument in MALDI mode. The formation of a HupA dimmer in a vacuum was observed and several matrices were found that were able to inhibit its formation. The structures of the neutral and protonated form of the HupA molecule were calculated and optimized using a Hyperchem program. Detection limit using MALDI TOF MS in the model sample was 5.3pg. MALDI TOF MS was also applied to the direct detection of the drug in medical preparations and in human serum. The limit of detection in plasma was 14.2pg with a signal-to-noise ratio of 3:1. However, the sensitivity was not as high as it usually is in MALDI. Therefore, a new method for the derivatization of HupA was developed using fluorescent labelling with rhodamine B isothiocyanate (RBITC). A limit of detection using capillary electrophoresis laser induced fluorescence detection (CE-LIF) equal to 4x10(-9)moll(-1) was reached. PMID:19071686

Hameda, A Ben; Táborský, P; Peña-Méndez, E M; Havel, J

2007-04-30

35

Separation efficiency of a chemical warfare agent simulant in an atmospheric pressure ion mobility time-of-flight mass spectrometer (IM(tof)MS)  

Microsoft Academic Search

An electrospray ionization atmospheric pressure ion mobility orthogonal reflector time-of-flight mass spectrometer (IM(tof)MS) that routinely achieves mobility and mass separation efficiencies in line with theoretical limits is reported. The maximum IM(tof)MS efficiency for a given instrumental design depends widely upon the various key parameters such as voltage, temperature, initial pulse width, interface and reflectron energies. Optimization of the current IM(tof)MS

Wes E. Steiner; William A. English; Herbert H. Hill

2005-01-01

36

Use of ProteinChip™ array surface enhanced laser desorption\\/ionization time-of-flight mass spectrometry (SELDI-TOF MS) to identify thymosin ? -4, a differentially secreted protein from lymphoblastoid cell lines  

Microsoft Academic Search

The identification of proteins differentially expressed between cancer and normal cells is vital for the development of cancer\\u000a diagnostics, therapeutics and vaccines. Using a ProteinChip Biomarker System (Ciphergen Biosystems, Fremont, CA) which combines\\u000a ProteinChip™ technology with time-of-flight mass spectrometry, we have developed a simple method to screen and identify differentially\\u000a secreted proteins from tumor cell lines. Mass spectra of the

Deborah L. Diamond; Yanni Zhang; Alexander Gaiger; Molly Smithgall; Thomas S. Vedvick; Darrick Carter

2003-01-01

37

Investigations on aberrant glycosylation of glycosphingolipids in colorectal cancer tissues using liquid chromatography and matrix-assisted laser desorption time-of-flight mass spectrometry (MALDI-TOF-MS).  

PubMed

Cancer is a leading cause of death and alterations of glycosylation are characteristic features of malignant cells. Colorectal cancer is one of the most common cancers and its exact causes and biology are not yet well understood. Here, we compared glycosylation profiles of colorectal tumor tissues and corresponding control tissues of 13 colorectal cancer patients to contribute to the understanding of this cancer. Using MALDI-TOF(/TOF)-MS and 2-dimensional LC-MS/MS we characterized enzymatically released and 2-aminobenzoic acid labeled glycans from glycosphingolipids. Multivariate data analysis revealed significant differences between tumor and corresponding control tissues. Main discriminators were obtained, which represent the overall alteration in glycosylation of glycosphingolipids during colorectal cancer progression, and these were found to be characterized by (1) increased fucosylation, (2) decreased acetylation, (3) decreased sulfation, (4) reduced expression of globo-type glycans, as well as (5) disialyl gangliosides. The findings of our current research confirm former reports, and in addition expand the knowledge of glycosphingolipid glycosylation in colorectal cancer by revealing new glycans with discriminative power and characteristic, cancer-associated glycosylation alterations. The obtained discriminating glycans can contribute to progress the discovery of biomarkers to improve diagnostics and patient treatment. PMID:23878401

Holst, Stephanie; Stavenhagen, Kathrin; Balog, Crina I A; Koeleman, Carolien A M; McDonnell, Liam M; Mayboroda, Oleg A; Verhoeven, Aswin; Mesker, Wilma E; Tollenaar, Rob A E M; Deelder, André M; Wuhrer, Manfred

2013-11-01

38

Investigations on Aberrant Glycosylation of Glycosphingolipids in Colorectal Cancer Tissues Using Liquid Chromatography and Matrix-Assisted Laser Desorption Time-of-Flight Mass Spectrometry (MALDI-TOF-MS)*  

PubMed Central

Cancer is a leading cause of death and alterations of glycosylation are characteristic features of malignant cells. Colorectal cancer is one of the most common cancers and its exact causes and biology are not yet well understood. Here, we compared glycosylation profiles of colorectal tumor tissues and corresponding control tissues of 13 colorectal cancer patients to contribute to the understanding of this cancer. Using MALDI-TOF(/TOF)-MS and 2-dimensional LC-MS/MS we characterized enzymatically released and 2-aminobenzoic acid labeled glycans from glycosphingolipids. Multivariate data analysis revealed significant differences between tumor and corresponding control tissues. Main discriminators were obtained, which represent the overall alteration in glycosylation of glycosphingolipids during colorectal cancer progression, and these were found to be characterized by (1) increased fucosylation, (2) decreased acetylation, (3) decreased sulfation, (4) reduced expression of globo-type glycans, as well as (5) disialyl gangliosides. The findings of our current research confirm former reports, and in addition expand the knowledge of glycosphingolipid glycosylation in colorectal cancer by revealing new glycans with discriminative power and characteristic, cancer-associated glycosylation alterations. The obtained discriminating glycans can contribute to progress the discovery of biomarkers to improve diagnostics and patient treatment.

Holst, Stephanie; Stavenhagen, Kathrin; Balog, Crina I. A.; Koeleman, Carolien A. M.; McDonnell, Liam M.; Mayboroda, Oleg A.; Verhoeven, Aswin; Mesker, Wilma E.; Tollenaar, Rob A. E. M.; Deelder, Andre M.; Wuhrer, Manfred

2013-01-01

39

Analysis of Wheat Prolamins, the Causative Agents of Celiac Sprue, Using Reversed Phase High Performance Liquid Chromatography (RP-HPLC) and Matrix-Assisted Laser Desorption Ionization Time of Flight Mass Spectrometry (MALDI-TOF-MS).  

PubMed

Wheat prolamins, commonly known as "gluten", are a complex mixture of 71-78 proteins, which constitute ~80% of the proteins in the wheat grains and supply 50% of the global dietary protein demand. Prolamins are also responsible for numerous gluten-induced disorders and determine the unique visco-elastic properties of the wheat dough. These properties necessitate the reliable determination of the prolamin composition in wheat grains and their derived products. Therefore, this study examined the impact of HPLC conditions, including column type, column temperature, flow rate, and the gradient of polar and non-polar solvents in the mobile phase, to improve the analytical resolution of prolamins. The following conditions were found optimal for analyses: column temperature 60 °C, flow rate 1.0 mL/min and an elution gradient of 20%-60% of 0.1% trifluoroacetic acid + acetonitrile in 60 min. For further improvement of resolution, gliadin and glutenin extracts were analyzed using MALDI-TOF-MS in combination with HPLC fractionation. Two semi-quantitative methods, densitometry of stained polyacrylamide gels and HPLC, were used to determine relative prolamin quantities and the correspondence between the methods was established. The combinatorial gluten analyses approach developed during the present study was used to analyze prolamin profiles of wheat transformants expressing DEMETER silencing artificial microRNA, and the results are discussed. PMID:24739977

Mejías, Jaime H; Lu, Xiaoqiao; Osorio, Claudia; Ullman, Jeffrey L; von Wettstein, Diter; Rustgi, Sachin

2014-01-01

40

Analysis of Wheat Prolamins, the Causative Agents of Celiac Sprue, Using Reversed Phase High Performance Liquid Chromatography (RP-HPLC) and Matrix-Assisted Laser Desorption Ionization Time of Flight Mass Spectrometry (MALDI-TOF-MS)  

PubMed Central

Wheat prolamins, commonly known as “gluten”, are a complex mixture of 71–78 proteins, which constitute ~80% of the proteins in the wheat grains and supply 50% of the global dietary protein demand. Prolamins are also responsible for numerous gluten-induced disorders and determine the unique visco-elastic properties of the wheat dough. These properties necessitate the reliable determination of the prolamin composition in wheat grains and their derived products. Therefore, this study examined the impact of HPLC conditions, including column type, column temperature, flow rate, and the gradient of polar and non-polar solvents in the mobile phase, to improve the analytical resolution of prolamins. The following conditions were found optimal for analyses: column temperature 60 °C, flow rate 1.0 mL/min and an elution gradient of 20%–60% of 0.1% trifluoroacetic acid + acetonitrile in 60 min. For further improvement of resolution, gliadin and glutenin extracts were analyzed using MALDI-TOF-MS in combination with HPLC fractionation. Two semi-quantitative methods, densitometry of stained polyacrylamide gels and HPLC, were used to determine relative prolamin quantities and the correspondence between the methods was established. The combinatorial gluten analyses approach developed during the present study was used to analyze prolamin profiles of wheat transformants expressing DEMETER silencing artificial microRNA, and the results are discussed.

Mejias, Jaime H.; Lu, Xiaoqiao; Osorio, Claudia; Ullman, Jeffrey L.; von Wettstein, Diter; Rustgi, Sachin

2014-01-01

41

Fingerprint analysis using mass spectrometry  

US Patent & Trademark Office Database

The present invention is directed to a method for determining the presence of a residue on or within a fingerprint using matrix-assisted mass spectrometric techniques. The matrix-assisted mass spectrometric technique can be selected from Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry Time-Of-Flight Mass Spectrometry (MALDI-TOF-MS) and/or Surface Assisted Laser Desorption/Ionisation Time-Of-Flight Mass Spectrometry (SALDI-TOF-MS).

2011-04-12

42

The SELDI-TOF MS Approach to Proteomics: Protein Profiling and Biomarker Identification  

Microsoft Academic Search

The need for methods to identify disease biomarkers is underscored by the survival-rate of patients diagnosed at early stages of cancer progression. Surface enhanced laser desorption\\/ionization time-of-flight mass spectrometry (SELDI-TOF MS) is a novel approach to biomarker discovery that combines two powerful techniques: chromatography and mass spectrometry. One of the key features of SELDI-TOF MS is its ability to provide

Haleem J. Issaq; Timothy D. Veenstra; Thomas P. Conrads; Donna Felschow

2002-01-01

43

Performance of mass spectrometric identification of bacteria and yeasts routinely isolated in a clinical microbiology laboratory using MALDI-TOF MS  

PubMed Central

Background Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) is an emerging technology newly applied to identifying bacterial and yeast strains. The aim of this study was to evaluate the clinical performance of the VITEK® MS system in the identification of bacteria and yeast strains routinely isolated from clinical samples. Methods We prospectively analyzed routine MALDI-TOF mass spectrometry identification in parallel with conventional phenotypic identification of bacteria and yeasts regardless of phylum or source of isolation. Discordant results were resolved with 16S rDNA or internal transcribed spacer (ITS) gene sequencing. Colonies (a single deposit on a MALDI disposable target without any prior extraction step) were analyzed using the VITEK® MS system. Peptide spectra acquired by the system were compared with the VITEK® MS IVD database Version 2.0, and the identification scores were recorded. Results Of the 1,181 isolates (1,061 bacterial isolates and 120 yeast isolates) analyzed, 99.5% were correctly identified by MALDI-TOF mass spectrometry; 95.7% identified to the species level, 3.6% identified to the genus level, and 0.3% identified within a range of species belonging to different genera. Conversely, 0.1% of isolates were misidentified and 0.4% were unidentified, partly because the species were not included in the database. Re-testing using a second deposit provided a successful identification for 0.5% of isolates unidentified with the first deposit. Our results show that the VITEK® MS system has exceptional performance in identifying bacteria and yeast by comparing acquired peptide spectra to those contained in its database. Conclusions MALDI-TOF mass spectrometry is a rapid, accurate, and relatively inexpensive method for bacterial and yeast identification. Our results demonstrate that the VITEK® MS system is a fast and reliable technique, and has the potential to replace conventional phenotypic identification for most bacterial and yeast strains routinely isolated in clinical microbiology laboratories.

Wang, Weiping; Xi, Haiyan; Huang, Mei; Wang, Jie; Fan, Ming; Chen, Yong; Shao, Haifeng

2014-01-01

44

MALDI-TOF MS in Prenatal Genomics  

PubMed Central

Summary Prenatal diagnosis aims either to provide the reassurance to the couples at risk of having an affected child by timely appropriate therapy or to give the parents a chance to decide the fate of the unborn babies with health problems. Invasive prenatal diagnosis (IPD) is accurate, however, carrying a risk of miscarriage. Non-invasive prenatal diagnosis (NIPD) has been developed based on the existing of fetal genetic materials in maternal circulation; however, a minority fetal DNA in majority maternal background DNA hinders the detections of fetal traits. Different protocols and assays, such as homogenous MassEXTEND (hME), single allele base extension reaction (SABER), precise measuring copy number variation of each allele, and quantitative methylation and expression analysis using the high-throughput sensitive matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS), allow NIPD for single gene disorders, fetal blood group genotyping and fetal aneuploidies as well as the development of fetal gender-independent biomarkers in maternal circulation for management of pathological pregnancies. In this review, we summarise the use of MALDI-TOF MS in prenatal genomics.

Zhong, Xiao Yan; Holzgreve, Wolfgang

2009-01-01

45

SELDI-TOF MS Proteomics in Breast Cancer  

Microsoft Academic Search

Background  Proteomic profiling is a rapidly developing technology that may enable early disease screening and diagnosis. Surface-enhanced\\u000a laser desorption ionization–time of flight mass spectrometry (SELDI-TOF MS) has demonstrated promising results in screening\\u000a and early detection of many diseases. In particular, it has emerged as a high-throughput tool for detection and differentiation\\u000a of several cancer types. This review aims to appraise published

Bashar A. Zeidan; Ramsey I. Cutress; Claire Hastie; Alex H. Mirnezami; Graham Packham; Paul A. Townsend

2009-01-01

46

Proteiomic patterns for endometrial cancer using SELDI-TOF-MS  

Microsoft Academic Search

Serum samples from endometrial cancer (EC) patients and healthy females were analyzed using surface-enhanced laser desorption-ionization\\u000a time-of-flight mass spectrometry (SELDI-TOF-MS) to discover the potential diagnostic biomarker for detection of EC. A preliminary\\u000a training set of spectra derived from 40 EC patients and 30 healthy women were used to develop a proteomic model that effectively\\u000a discriminated cancer patients from healthy women.

Li-rong Zhu; Wen-ying Zhang; Li Yu; Yan-hua Zheng; Jun Hu; Qin-ping LIAO

2008-01-01

47

Comparative SELDI-TOF-MS profiling of low-molecular-mass proteins from Lignosus rhinocerus (Cooke) Ryvarden grown under stirred and static conditions of liquid fermentation  

Microsoft Academic Search

Mushrooms are considered as important source of biologically active compounds which include low-molecular-mass protein\\/peptides (LMMP). In this study, we attempted to profile the LMMP from Lignosus rhinocerus, a wild medicinal mushroom, grown by static cultures (SC) and in stirred tank reactor (STR). Crude water extract (CWE) and protein fractions were profiled using H50 ProteinChip® arrays and SELDI-TOF-MS. Three protein peaks

Beng Fye Lau; Norhaniza Aminudin; Noorlidah Abdullah

2011-01-01

48

Quantitative matrix-assisted laser desorption/ionization mass spectrometry  

PubMed Central

This review summarizes the essential characteristics of matrix-assisted laser desorption/ionization (MALDI) time-of-flight mass spectrometry (TOF MS), especially as they relate to its applications in quantitative analysis. Approaches to quantification by MALDI-TOF MS are presented and published applications are critically reviewed.

Roder, Heinrich; Hunsucker, Stephen W.

2008-01-01

49

Comparative study of MALDI-TOF MS and VITEK 2 in bacteria identification  

PubMed Central

Background Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) has recently been introduced in diagnostic microbiology laboratories for the identification of bacterial and yeast strains isolated from clinical samples. This study aimed to evaluate the accuracy of MALDI-TOF MS in clinical microbiology diagnosis by comparing it with commonly-used VITEK 2 or gene sequencing. Methods The performances of MALDI-TOF MS and VITEK 2 were compared retrospectively for identifying routine isolates. Discrepancies were analyzed by gene sequencing analysis of the 16S genes. Results For 1,025 isolates, classified as 55 species of 25 genera, 1,021 (99.60%) isolates were accurately identified at the genus level, and 957 (93.37%) isolates at the species level by using MALDI-TOF MS. A total of 949 (92.59%) isolates were completely matched by both methods. Both methods found 76 unmatched isolates among which one strain had no definite identification by MALDI-TOF MS and VITEK 2 respectively. However, MALDI-TOF MS made no errors at the genus level while VITEK 2 made 6 (0.58%) errors at the genus level. At the species level, the identification error rates for MALDI-TOF MS and VITEK 2 were 5.56% and 6.24%, respectively. Conclusions With a lower identification error rate, MALDI-TOF MS has better performance than VITEK 2 in identifying bacteria found routinely in the clinical laboratory. It is a quick and cost-effective technique, and has the potential to replace conventional phenotype methods in identifying common bacterial isolates in clinical microbiology laboratories.

Guo, Ling; Ye, Liyan; Zhao, Qiang; Ma, Yanning; Yang, Jiyong

2014-01-01

50

Limitations in SELDI-TOF MS whole serum proteomic profiling with IMAC surface to specifically detect colorectal cancer  

Microsoft Academic Search

BACKGROUND: Surface enhanced laser desorption and ionization time-of-flight mass spectrometry (SELDI-TOF-MS) analysis on serum samples was reported to be able to detect colorectal cancer (CRC) from normal or control patients. We carried out a validation study of a SELDI-TOF MS approach with IMAC surface sample processing to identify CRC. METHODS: A retrospective cohort of 338 serum samples including 154 CRCs,

Qi Wang; Jing Shen; Zhen-fu Li; Jian-zheng Jie; Wen-yue Wang; Jin Wang; Zhong-tao Zhang; Zhi-xia Li; Li Yan; Jin Gu

2009-01-01

51

Wine yeast typing by MALDI-TOF MS.  

PubMed

For the production of wine, the most important industrially used yeast species is Saccharomyces cerevisiae. Years of experience have shown that wine quality and property are significantly affected by the employed strain conducting the fermentation. Consequently, the ability of a strain level differentiation became an important requirement of modern winemaking. In our study, we showed that the differentiation by time-consuming and laborious biochemical and DNA-based methods to enable a constant beverage quality and characteristics can be replaced by matrix-assisted-laser-desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), accompanied by the additional benefit of an application prediction. Mass fingerprints of 33 Saccharomyces strains, which are commonly used for varying wine fermentations, were generated by MALDI-TOF MS upon optimized sample preparation and instrument settings and analyzed by a cluster analysis for strain or ecotype-level differentiation. As a reference method, delta-PCR was chosen to study the genetic diversity of the employed strains. Finally, the cluster analyses of both methods were compared. It could be shown that MALDI-TOF MS, acting at proteome level, provides valuable information about the relationship between yeast strains and their application potential according to their MALDI mass fingerprint. PMID:24615383

Usbeck, Julia C; Wilde, Caroline; Bertrand, Dave; Behr, Jürgen; Vogel, Rudi F

2014-04-01

52

Application of MALDI-TOF MS for the Identification of Food Borne Bacteria  

PubMed Central

Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) has recently emerged as a powerful tool for the routine identification of clinical isolates. MALDI-TOF MS based identification of bacteria has been shown to be more rapid, accurate and cost-efficient than conventional phenotypic techniques or molecular methods. Rapid and reliable identification of food-associated bacteria is also of crucial importance for food processing and product quality. This review is concerned with the applicability of MALDI-TOF MS for routine identification of foodborne bacteria taking the specific requirements of food microbiological laboratories and the food industry into account. The current state of knowledge including recent findings and new approaches are discussed.

Pavlovic, Melanie; Huber, Ingrid; Konrad, Regina; Busch, Ulrich

2013-01-01

53

A critical assessment of SELDI-TOF-MS for biomarker discovery in serum and tissue of patients with an ovarian mass  

PubMed Central

Background Less than 25% of patients with a pelvic mass who are presented to a gynecologist will eventually be diagnosed with epithelial ovarian cancer. Since there is no reliable test to differentiate between different ovarian tumors, accurate classification could facilitate adequate referral to a gynecological oncologist, improving survival. The goal of our study was to assess the potential value of a SELDI-TOF-MS based classifier for discriminating between patients with a pelvic mass. Methods Our study design included a well-defined patient population, stringent protocols and an independent validation cohort. We compared serum samples of 53 ovarian cancer patients, 18 patients with tumors of low malignant potential, and 57 patients with a benign ovarian tumor on different ProteinChip arrays. In addition, from a subset of 84 patients, tumor tissues were collected and microdissection was used to isolate a pure and homogenous cell population. Results Diagonal Linear Discriminant Analysis (DLDA) and Support Vector Machine (SVM) classification on serum samples comparing cancer versus benign tumors, yielded models with a classification accuracy of 71-81% (cross-validation), and 73-81% on the independent validation set. Cancer and benign tissues could be classified with 95-99% accuracy using cross-validation. Tumors of low malignant potential showed protein expression patterns different from both benign and cancer tissues. Remarkably, none of the peaks differentially expressed in serum samples were found to be differentially expressed in the tissue lysates of those same groups. Conclusion Although SELDI-TOF-MS can produce reliable classification results in serum samples of ovarian cancer patients, it will not be applicable in routine patient care. On the other hand, protein profiling of microdissected tumor tissue may lead to a better understanding of oncogenesis and could still be a source of new serum biomarkers leading to novel methods for differentiating between different histological subtypes.

2012-01-01

54

Direct Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry Improves Appropriateness of Antibiotic Treatment of Bacteremia  

Microsoft Academic Search

Matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) allows the identification of microorganisms directly from positive blood culture broths. Use of the MALDI-TOF MS for rapid identification of microorganisms from blood culture broths can reduce the turnaround time to identification and may lead to earlier appropriate treatment of bacteremia. During February and April 2010, direct MALDI-TOF MS was

Anne L. M. Vlek; Marc J. M. Bonten; C. H. Edwin Boel

2012-01-01

55

Tropical Greenhouse Measurements of Volatile Organic Compounds Using Switchable Reagent Ion Proton-Transfer-Reaction Time-of-Flight Mass Spectromety (PTR-TOF-MS)  

NASA Astrophysics Data System (ADS)

In this presentation, we will summarize the results of measurements made in an approximately 1300 m3 tropical greenhouse at the Johannes Gutenberg University botanical garden in Mainz Germany conducted over a one month period. The greenhouse is home to a large variety of plant species from hot and humid regions of the world. The greenhouse is also host to several crops such as Cocoa and Cola Nut as well as ornamental plants. A particular focus of the species maintained are those which are considered ant plants, or plants which have an intimate relationship with ants in tropical habitats. Volatile organic compounds (VOCs) were measured using a Switchable Reagent Ion Proton-Transfer-Reaction Time-of-Flight Mass Spectrometer (PTR-TOF-MS) using H3O+, NO+, and O2+ ion chemistry. Measurements will be presented both for primary emissions observed in the closed greenhouse atmosphere as well as the oxidation products observed after the introduction of ambient ozone. The high resolving power (5000 m/?m) of the time-of-flight instrument allows for the separation of isobaric species. In particular, both isoprene (68.1170 amu) and furan (68.0740 amu) were observed and separated as primary emissions during this study. The significance of this will be discussed in terms of both atmospheric implications as well as with respect to previous measurements of isoprene obtained using quadrupole PTR-MS where isobaric separation of these compounds is not possible. Additionally observed species (e.g. Methanol, Acetaldehyde, MVK and MEK) will be discussed in detail with respect to their behavior as a function of light, temperature and relative humidity. The overall instrument performance of the PTR-TOF-MS technique using the H3O+, NO+, and O2+ primary ions for the measurement of VOCs will be evaluated.

Veres, P.; Auld, J.; Williams, J.

2012-04-01

56

Evaluation of MALDI-TOF MS as a tool for high-throughput dereplication.  

PubMed

The present study examined the suitability of matrix assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS) for the rapid grouping of bacterial isolates, i.e. dereplication. Dereplication is important in large-scale isolation campaigns and screening programs since it can significantly reduce labor intensity, time and costs in further downstream analyses. Still, current dereplication techniques are time consuming and costly. MALDI-TOF MS is an attractive tool since it performs fast and cheap analyses with the potential of automation. However, its taxonomic resolution for a broad diversity of bacteria remains largely unknown. To verify the suitability of MALDI-TOF MS for dereplication, a total of 249 unidentified bacterial isolates retrieved from the rhizosphere of potato plants, were analyzed with both MALDI-TOF MS and repetitive element sequence based polymerase chain reaction (rep-PCR). The latter technique was used as a benchmark. Cluster analysis and inspection of the profiles showed that for 204 isolates (82%) the taxonomic resolution of both techniques was comparable, while for 45 isolates (18%) one of both techniques had a higher taxonomic resolution. Additionally, 16S rRNA gene sequence analysis was performed on all members of each delineated cluster to gain insight in the identity and sequence similarity between members in each cluster. MALDI-TOF MS proved to have higher reproducibility than rep-PCR and seemed to be more promising with respect to high-throughput analyses, automation, and time and cost efficiency. Its taxonomic resolution was situated at the species to strain level. The present study demonstrated that MALDI-TOF MS is a powerful tool for dereplication. PMID:21699925

Ghyselinck, Jonas; Van Hoorde, Koenraad; Hoste, Bart; Heylen, Kim; De Vos, Paul

2011-09-01

57

Comparison of MALDI-TOF MS, gene sequencing and the Vitek 2 for identification of seventy-three clinical isolates of enteropathogens  

PubMed Central

Objective This study was performed to evaluate the analytical and practical performance of the matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) compared to the sequencing method and the Vitek 2 system for identi?cation of enteropathogens in the clinical microbiology laboratory. Methods Ten type strains and 73 clinical isolates of enteropathogens representing eight genera were analyzed by MALDI-TOF MS. All isolates were also characterized by gene sequencing allowing interpretation of the results from MALDI-TOF MS. In addition, MALDI-TOF MS was compared with the Vitek 2 system for the identi?cation of ten isolates of Aeromonas and six of Salmonella. Results As previously known, identification between Shigella and Escherichia coli is not possible to distinguish. MALDI-TOF MS produced the correct identifications for all other type strains and clinical isolates to the genus level. Fifteen Campylobacter jejuni, six Campylobacter coli, three Plesiomonas shigelloides, three Yersinia enterocolitica, two Clostridium difficile, one Vibrio parahaemolyticus, one Vibrio fluvialis, and one Vibrio cholera were all correctly identi?ed to the species level. Genus and species identifications of ten Aeromonas and six Salmonella isolates by MALDI-TOF MS were consistent with those by the Vitek 2, but with much less cost and about ten times faster. Conclusions This study demonstrates that MALDI-TOF MS is a powerful tool for fast, accurate and low-cost identi?cation of enteropathogens in the clinical microbiology laboratory.

Deng, Jiankai; Fu, Liang; Wang, Ruilian; Ding, Xixia; Jiang, Lingxiao; Fang, Yanping; Jiang, Changhong; Lin, Lijuan; Che, Xiaoyan

2014-01-01

58

MALDI-TOF MS Distinctly Differentiates Nontypable Haemophilus influenzae from Haemophilus haemolyticus  

PubMed Central

Nontypable Haemophilus influenzae (NTHi) and Haemophilus haemolyticus exhibit different pathogenicities, but to date, there remains no definitive and reliable strategy for differentiating these strains. In this study, we evaluated matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) as a potential method for differentiating NTHi and H. haemolyticus. The phylogenetic analysis of concatenated 16S rRNA and recombinase A (recA) gene sequences, outer membrane protein P6 gene sequencing and single-gene PCR were used as reference methods. The original reference database (ORD, provided with the Biotyper software) and new reference database (NRD, extended with Chinese strains) were compared for the evaluation of MALDI-TOF MS. Through a search of the ORD, 76.9% of the NTHi (40/52) and none of the H. haemolyticus (0/20) strains were identified at the species level. However, all NTHi and H. haemolyticus strains used for identification were accurately recognized at the species level when searching the NRD. From the dendrogram clustering of the main spectra projections, the Chinese and foreign H. influenzae reference strains were categorized into two distinct groups, and H. influenzae and H. haemolyticus were also separated into two categories. Compared to the existing methods, MALDI-TOF MS has the advantage of integrating high throughput, accuracy and speed. In conclusion, MALDI-TOF MS is an excellent method for differentiating NTHi and H. haemolyticus. This method can be recommended for use in appropriately equipped laboratories.

Zhang, Huifang; Zhang, Yongchan; Gao, Yuan; Xu, Li; Lv, Jing; Wang, Yingtong; Zhang, Jianzhong; Shao, Zhujun

2013-01-01

59

[Rapid identification of two new isomers in bear bile powder by LC-Q-TOF-MS combined with PCC oxidation].  

PubMed

A rapid method of Liquid chromatography-quadrupole time-of-flight mass spectrometry (LC-Q-TOF-MS) combined with pyridinium chlorochromate (PCC) oxidation has been developed to determine chemical structures of two novel isomers in bear bile powder. Derivatives of ursodeoxycholic acid (UDCA) and chenodeoxycholic acid (CDCA) were semi-synthesized by PCC oxidation, then were analyzed by LC-Q-TOF-MS. Separation was carried out on a reverse column with the mobile phase of acetonitrile-0.1% formic acid (45:55). The data of Q-TOF-MS was acquired by MS, MS/MS, positive and negative modes. Since UDCA and CDCA were stereochemical isomeric at an alcohol position, two oxidation products were same and have been confirmed by LC-Q-TOF-MS. Other two products were also determined based on the PCC oxidation theory. Samples of bear bile powder were dissolved by methanol and measured by LC-Q-TOF-MS. Two unknown peaks were found and identified by matching their retention times and accurate mass spectra ions with PCC oxidation productS. Finally, the structures of two new bile acids in bear bile powder were confirmed as 3alpha-hydroxy-7-oxo-5beta-cholanic acid, 7alpha-hydroxy-3-oxo-5beta-cholanic acid, respectively. PMID:24199568

Jian, Long-Hai; Hu, Chun; Yu, Hong; Wang, Ke; Ji, Shen

2013-07-01

60

Preoperatively molecular staging with CM10 ProteinChip and SELDI-TOF-MS for colorectal cancer patients  

Microsoft Academic Search

Objectives: To detect the serum proteomic patterns by using SELDI-TOF-MS (surface enhanced laser desorption\\/ionization-time\\u000a of flight-mass spectrometry) technology and CM10 ProteinChip in colorectal cancer (CRC) patients, and to evaluate the significance\\u000a of the proteomic patterns in the tumour staging of colorectal cancer. Methods: SELDI-TOF-MS and CM10 ProteinChip were used\\u000a to detect the serum proteomic patterns of 76 patients with colorectal

Wen-hong Xu; Yi-ding Chen; Yue Hu; Jie-kai Yu; Xian-guo Wu; Tie-jun Jiang; Shu Zheng; Su-zhan Zhang

2006-01-01

61

The analysis of polystyrene and polystyrene aggregates into the mega dalton mass range by cryodetection MALDI TOF MS  

Microsoft Academic Search

Mass spectra of atactic polystyrene were collected into the mega-dalton mass range with a matrix-assisted laser desorption\\u000a ionization time of flight (MALDI TOF) mass spectrometer, which incorporates a cryodetector comprised of an array of 16 superconducting\\u000a tunnel junctions (STJ). The STJ cryodetector, theoretically, has no loss in signal response at any mass compared with the\\u000a reduced signal found at high

Alexander A. Aksenov; Mark E. Bier

2008-01-01

62

Analysis of Organic Nitrogen Compounds in Urban Aerosol Samples Using GCxGC-TOF\\/MS  

Microsoft Academic Search

Despite the fact that a significant number of organic and inorganic compounds have been measured in aerosol samples, relatively little is known about the organic nitrogen (ON) content. The ON components of 23 urban aerosol samples were characterized using a direct thermal desorption technique (DTD) together with comprehensive two-dimensional gas chromatography-time of flight mass spectrometry (GCxGC-TOF\\/MS). Between 17 and 57

Mustafa Z. Özel; Martyn W. Ward; Jacqueline F. Hamilton; Alastair C Lewis; Teresa Raventós-Duran; Roy M. Harrison

2010-01-01

63

Research progress in SELDI-TOF MS and its clinical applications  

Microsoft Academic Search

Proteinchip profiling is a powerful and innovative proteomic technology for the discovery of biomarkers and the development of diagnostic\\/prognostic assays. On the basis of surface-enhanced laser desorption\\/ionization time-of-flight mass spectrometry (SELDI-TOF MS), Ciphergen’s proteinchip system offers a single, unified, and high throughput platform for a multitude of proteomic research applications. Proteins are the major functional components of the cell. The

William Chi-Shing CHO

2006-01-01

64

Validation of SELDI-TOF MS serum protein profiles for renal cell carcinoma in new populations  

Microsoft Academic Search

Currently, no suitable biomarker for the early detection or follow-up of renal cell carcinoma (RCC) is available. We aimed to validate previously reported potential serum biomarkers for RCC obtained with Surface Enhanced Laser Desorption Ionisation-Time of Flight Mass Spectrometry (SELDI-TOF MS) in our laboratory using distinct patient populations. Two sets of sera from RCC patients and healthy controls (HC) were

Judith Y M N Engwegen; Niven Mehra; John B A G Haanen; Johannes M G Bonfrer; Jan H M Schellens; Emile E Voest; Jos H Beijnen; Judith YMN Engwegen

2007-01-01

65

SELDI-TOF MS profiling of serum for detection of nasopharyngeal carcinoma  

Microsoft Academic Search

BACKGROUND: No satisfactory biomarkers are currently available to screen for nasopharyngeal carcinoma (NPC). We have developed and evaluated surface-enhanced laser desorption\\/ionization time-of-flight mass spectrometry (SELDI-TOF MS) for detection and analysis of multiple proteins for distinguishing individuals with NPC from control individuals. METHODS: A preliminary learning set and a classification tree of spectra derived from 24 patients with NPC and a

Yuan-Jiao Huang; Chao Xuan; Bei-Bei Zhang; Ming Liao; Kai-Feng Deng; Min He; Jin-Min Zhao

2009-01-01

66

Evaluation of the MALDI TOF-MS method for identification of Candida strains isolated from blood cultures.  

PubMed

Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI TOF-MS) allows rapid and accurate identification of microorganisms. It is being used increasingly and becoming an important tool in clinical laboratories. Phenotypic identification of Candida species remains labor- and time consuming, and the results may sometimes be inconclusive. Rapid and reliable species identification of Candida is essential for antifungal treatment due to species-specific susceptibility patterns. In this study, we evaluated the performance of MALDI TOF-MS for identification of Candida strains. A total of 281 clinical Candida strains isolated from blood cultures were included in this study. Candida species were identified with conventional methods and automated VITEK 2 YST panels as well as with MALDI TOF-MS. Isolates with discrepant results were subjected to DNA sequencing of the internal transcribed spacer (ITS) region (ITS1-5.8S-ITS2). Ninety-four percent of the isolates were identified correctly by VITEK 2 and MALDI TOF-MS. Altogether, MALDI-TOF MS yielded the correct species identification for 281 (100%) clinical Candida isolates. MALDI-TOF proved to be a rapid and reliable method for identification of Candida strains in the clinical laboratory. PMID:22578939

Yaman, Görkem; Akyar, I??n; Can, Simge

2012-05-01

67

Reliable identification at the species level of Brucella isolates with MALDI-TOF-MS  

PubMed Central

Background The genus Brucella contains highly infectious species that are classified as biological threat agents. The timely detection and identification of the microorganism involved is essential for an effective response not only to biological warfare attacks but also to natural outbreaks. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) is a rapid method for the analysis of biological samples. The advantages of this method, compared to conventional techniques, are rapidity, cost-effectiveness, accuracy and suitability for the high-throughput identification of bacteria. Discrepancies between taxonomy and genetic relatedness on the species and biovar level complicate the development of detection and identification assays. Results In this study, the accurate identification of Brucella species using MALDI-TOF-MS was achieved by constructing a Brucella reference library based on multilocus variable-number tandem repeat analysis (MLVA) data. By comparing MS-spectra from Brucella species against a custom-made MALDI-TOF-MS reference library, MALDI-TOF-MS could be used as a rapid identification method for Brucella species. In this way, 99.3% of the 152 isolates tested were identified at the species level, and B. suis biovar 1 and 2 were identified at the level of their biovar. This result demonstrates that for Brucella, even minimal genomic differences between these serovars translate to specific proteomic differences. Conclusions MALDI-TOF-MS can be developed into a fast and reliable identification method for genetically highly related species when potential taxonomic and genetic inconsistencies are taken into consideration during the generation of the reference library.

2011-01-01

68

Proteomic analysis of phosphoproteins sensitive to a phosphatidylinositol 3-kinase inhibitor, ZSTK474, by using SELDI-TOF MS  

Microsoft Academic Search

BACKGROUND: Phosphoproteins play important roles in a vast series of biological processes. Recent proteomic technologies offer the comprehensive analyses of phosphoproteins. Recently, we demonstrated that surface-enhanced laser desorption\\/ionization time of flight mass (SELDI-TOF MS) would detect phosphoproteins quantitatively, which was a new application of SELDI-TOF MS. RESULTS: We combined immobilized metal affinity chromatography (IMAC) with SELDI-TOF MS. After SELDI-TOF MS

Tetsuyuki Akashi; Takao Yamori

2009-01-01

69

Advances in Identification of Clinical Yeast Isolates by Use of Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry  

PubMed Central

Matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS)-based identification is being adopted by clinical laboratories for routine identification of microorganisms. To date, the majority of studies have focused on the performance and optimization of MALDI-TOF MS for the identification of bacterial isolates. We review recent literature describing the use of MALDI-TOF MS for the routine identification of a variety of yeasts and yeast-like isolates. Specific topics include the effect of optimized or streamlined extraction methods, modified scoring thresholds, expanded reference libraries, and the possibility of conducting antifungal susceptibility testing using MALDI-TOF MS.

Buchan, Blake W.

2013-01-01

70

MALDI-TOF MS identification of anaerobic bacteria: assessment of pre-analytical variables and specimen preparation techniques.  

PubMed

Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) has emerged as a tool for identifying clinically relevant anaerobes. We evaluated the analytical performance characteristics of the Bruker Microflex with Biotyper 3.0 software system for identification of anaerobes and examined the impact of direct formic acid (FA) treatment and other pre-analytical factors on MALDI-TOF MS performance. A collection of 101 anaerobic bacteria were evaluated, including Clostridium spp., Propionibacterium spp., Fusobacterium spp., Bacteroides spp., and other anaerobic bacterial of clinical relevance. The results of our study indicate that an on-target extraction with 100% FA improves the rate of accurate identification without introducing misidentification (P<0.05). In addition, we modify the reporting cutoffs for the Biotyper "score" yielding acceptable identification. We found that a score of ?1.700 can maximize the rate of identification. Of interest, MALDI-TOF MS can correctly identify anaerobes grown in suboptimal conditions, such as on selective culture media and following oxygen exposure. In conclusion, we report on a number of simple and cost-effective pre- and post-analytical modifications could enhance MALDI-TOF MS identification for anaerobic bacteria. PMID:24666700

Hsu, Yen-Michael S; Burnham, Carey-Ann D

2014-06-01

71

A Rapid MALDI-TOF MS Identification Database at Genospecies Level for Clinical and Environmental Aeromonas Strains  

PubMed Central

The genus Aeromonas has undergone a number of taxonomic and nomenclature revisions over the past 20 years, and new (sub)species and biogroups are continuously described. Standard identification methods such as biochemical characterization have deficiencies and do not allow clarification of the taxonomic position. This report describes the development of a matrix-assisted laser desorption/ionisation–time of flight mass spectrometry (MALDI-TOF MS) identification database for a rapid identification of clinical and environmental Aeromonas isolates.

Benagli, Cinzia; Demarta, Antonella; Caminada, AnnaPaola; Ziegler, Dominik; Petrini, Orlando; Tonolla, Mauro

2012-01-01

72

Study of distinct protein profiles for early diagnosis of NSCLC using LCM and SELDI-TOF-MS  

Microsoft Academic Search

No biomarker has been available to detect early lung cancer so far. The aim of this study is to screen biomarker patterns\\u000a for early diagnosis of non-small cell lung cancer (NSCLC) using laser capture microdissection (LCM) and surface-enhanced laser\\u000a desorption ionization time-of-flight mass spectrometry (SELDI-TOF-MS). The 3 groups of the interested cells from 13 NSCLC\\u000a tissues, 11 normal lung tissues

Shuanying Yang; Yandong Nan; Yingxuan Tian; Wei Zhang; Bin Zhou; Lina Bu; Shufen Huo; Guoan Chen; Jiekai Yu; Shu Zheng

2008-01-01

73

Original Article Proteomic Profiling of Hepatitis B Virus-related Hepatocellular Carcinoma in China: a SELDI-TOF-MS Study  

Microsoft Academic Search

Hepatocellular carcinoma (HCC) is one of the most common malignancies with high mortality, but its underlying molecular mechanisms remain not well understood. High-throughput, proteomic techniques targeting unique biological molecules may provide novel insights into HCC pathogenesis and prognosis. In this study, we systemically investigated tissue biomarkers of HCC by using surface-enhanced laser desorption and ionization time-of-flight mass spectrometry (SELDI-TOF-MS) technique.

Jianzhong Zhang; Dong Li; Yanhua Zheng; Yan Cui; Kai Feng; Jinlian Zhou; Jihua Wu

74

High throughput identification of components from traditional Chinese medicine herbs by utilizing graphene or graphene oxide as MALDI-TOF-MS matrix.  

PubMed

In this work, graphene or graphene oxide was utilized, for the first time, to identify small molecular components from traditional Chinese medicine (TCM) herbs, by acting as matrix of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). Due to the large surface area of graphene or graphene oxide, the analytes were trapped tightly to the matrix, which avoids the contamination of the ion source and vacuum system. Besides, their excellent electronic, thermal and mechanical properties make them desired matrices for MALDI-TOF-MS. Stable analysis was achieved with no background inference even at the concentration of 100 nM. Moreover, the limit of detection (LOD) could be greatly lowered by utilizing graphene or graphene oxide as a pre-enrichment adsorbent. In summary, the promoted MALDI-TOF-MS methodology was demonstrated to be simple, sensitive, fast, cost effective and, most importantly, high throughput. PMID:21834019

Liu, Yang; Liu, Junyan; Yin, Peng; Gao, Mingxia; Deng, Chunhui; Zhang, Xiangmin

2011-08-01

75

MALDI-TOF MS fingerprinting facilitates rapid discrimination of phylotypes I, II and III of Propionibacterium acnes.  

PubMed

Matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is widely used today for species determination of bacteria and fungi in routine microbiological laboratories, and can also be used for subtyping of bacteria, such as Bacteroides fragilis. Propionibacterium acnes is frequently referred to as an anaerobic skin commensal of relatively low pathogenicity. In addition to its accepted pathogenic role in acne, P. acnes is now emerging as an important opportunistic pathogen in many other clinical situations, including late-stage prosthetic joint infections, osteomyelitis, endocarditis, endophthalmitis, post-neurosurgical infections and possibly prostate cancer. At the population genetic level, P. acnes can be differentiated into a number of distinct phylogroups, known as types IA1, IA2, IB, IC, II and III, which may be associated with different types of infections and clinical conditions. The aim of the present study was to evaluate MS-based typing for resolution of these genetic groups after routine identification by MALDI-TOF MS (Bruker MALDI Biotyper). The software package ClinProTools 2.2 was used to analyze the protein based mass spectra of reference strains belonging to types IA, IB, IC, II and III. Phylogroup-specific peaks and peak shifts were then identified visually. In addition, peak variations between the different types of P. acnes were investigated by using FlexAnalysis 3.3 software (Bruker). A differentiating library was created, which was used to type further 48 clinical isolates of P. acnes. Typing data obtained by MALDI-TOF MS were then compared with the results from Multilocus Sequence Typing (MLST). Most of the clinical isolates (n = 19) belonged to the type IA grouping according to MALDI-TOF MS. By MLST, all isolates were identified as type IA1. Twenty-one clinical isolates belonged to the type IB cluster based on both MALDI-TOF MS and MLST typing. Eight clinical isolates were identified as type II strains by both typing methods and all the type III reference strains could be distinguished by the presence of a unique type III-specific peak (7238 Da) by the MALDI-TOF MS. Our study demonstrates that MALDI-TOF MS is a reliable and powerful tool for rapid identification and typing of P. acnes strains from the main genetic divisions of the species. PMID:23485355

Nagy, Elisabeth; Urbán, Edit; Becker, Simone; Kostrzewa, Markus; Vörös, Andrea; Hunyadkürti, Judit; Nagy, István

2013-04-01

76

Serum proteomic profiling of dementia with Lewy bodies: diagnostic potential of SELDI-TOF MS analysis  

Microsoft Academic Search

Summary  Dementia with Lewy bodies (DLB) is the second most common senile degenerative dementia after Alzheimer’s disease (AD). The\\u000a presentation of overlapping symptoms between these two disorders leads to difficulties in the determination of clinical entities.\\u000a Serum samples were subjected to surface-enhanced laser desorption\\/ionization time-of-flight mass spectrometry (SELDI-TOF MS)\\u000a analysis in order to identify a diagnostic marker for DLB. Four putative

K. Wada-Isoe; K. Michio; K. Imamura; K. Nakaso; M. Kusumi; H. Kowa; K. Nakashima

2007-01-01

77

Diagnostic application of serum proteomic patterns in early gastric cancer patients by SELDI-TOF-MS  

Microsoft Academic Search

Objective  Surface-enhanced laser desorption\\/ionization time-of-flight mass spectrometry (SELDI-TOF-MS) is one of the currently used\\u000a techniques to identify biomarkers for cancers. This study was planned to make a proteomic analysis on the serum of stage I\\u000a gastric cancer patients and establish a early diagnostic model for identifying stage I gastric cancer preliminarily.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  A total of 229 serum samples including 169 pathologically confirmed

Chunwei Li; Dianliang Zhang; Jian Zhang; Fengbo Sun; Lei Mi

2011-01-01

78

Detection and quantification of bacterial spoilage in milk and pork meat using MALDI-TOF-MS and multivariate analysis.  

PubMed

Microbiological safety is one of the cornerstones of quality control in the food industry. Identification and quantification of spoilage bacteria in pasteurized milk and meat in the food industry currently relies on accurate and sensitive yet time-consuming techniques which give retrospective values for microbial contamination. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS), a proven technique in the field of protein and peptide identification and quantification, may be a valuable alternative approach for the rapid assessment of microbial spoilage. In this work we therefore developed MALDI-TOF-MS as a novel analytical approach for the assessment of food that when combined with chemometrics allows for the detection and quantification of milk and pork meat spoilage bacteria. To develop this approach, natural spoilage of pasteurized milk and raw pork meat samples incubated at 15 °C and at room temperature, respectively, was conducted. Samples were collected for MALDI-TOF-MS analysis (which took 4 min per sample) at regular time intervals throughout the spoilage process, with concurrent calculation and documentation of reference total viable counts using traditional microbiological methods (these took 2 days). Multivariate statistical techniques such as principal component discriminant function analysis, canonical correlation analysis, partial least-squares (PLS) regression, and kernel PLS (KPLS) were used to analyze the data. The results from MALDI-TOF-MS combined with PLS or KPLS gave excellent bacterial quantification results for both milk and meat spoilage, and typical root mean squared errors for prediction in test spectra were between 0.53 and 0.79 log unit. Overall these novel findings strongly indicate that MALDI-TOF-MS when combined with chemometric approaches would be a useful adjunct for routine use in the milk and meat industry as a fast and accurate viable bacterial detection and quantification method. PMID:22698768

Nicolaou, Nicoletta; Xu, Yun; Goodacre, Royston

2012-07-17

79

Characterization of Microorganisms by MALDI Mass Spectrometry  

Microsoft Academic Search

Matrix-assisted laser desorption\\/ionization-time-of-flight mass spectrometry (MALDI-TOF MS) for characterization and analysis of microorganisms, specifically bacteria, is described here as a rapid screening tool. The objective of this technique is not comprehensive protein analysis of a microorganism but rather a rapid screening of the organism and the accessible protein pattern for characterization and distinction. This method is based on the ionization

Catherine E. Petersen; Nancy B. Valentine; Karen L. Wahl

2008-01-01

80

Novel urine hepcidin assay by mass spectrometry  

Microsoft Academic Search

The hepatic peptide hormone hepcidin is the central regulator of iron metabolism and mediator of anemia of inflammation. To date, only one specific immuno-dot assay to measure hepcidin in urine had been documented. Here we report an alternative approach for quantification of hepcidin in urine by surface-enhanced laser desorption\\/ionization time-of-flight mass spectrometry (SELDI-TOF-MS). Peptide peaks were detected corresponding to the

Erwin Kemna; Harold Tjalsma; Coby Laarakkers; Elizabeta Nemeth; Hans Willems; Dorine Swinkels

2005-01-01

81

MALDI-TOF MS, a useful instrument for differentiating metallo-?-lactamases in Enterobacteriaceae and Pseudomonas spp.  

PubMed

We have evaluated a matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) method for the identification of carbapenemases and for distinguishing metallo-?-lactamases (MBLs). A total of 49 noncarbapenemase-producing and 14 carbapenemase-producing Enterobacteriaceae and Pseudomonas aeruginosa clinical strains, previously characterized by PCR, were included in the study. With MALDI-TOF MS, the presence of carbapenemases was confirmed by the detection of ertapenem hydrolysis (lost of molecular peaks: 476·5 Da, 498·5 Da, 520·5 Da and presence of degradation products) in the mixture of the bacteria with the antibiotic, and classification was achieved by selective inhibition of carbapenemase activity (the ertapenem molecular peak was maintained) with ethylenediaminetetraacetic acid (EDTA). We obtained a good concordance among the results of PCR and MALDI-TOF MS. This method appears to be simple, fast and reliable for distinguishing in few hours different classes of carbapenemases, which can be very useful for epidemiological studies or to establish a specific antimicrobial therapy. Significance and impact of the study: MALDI-TOF mass spectrometry is increasingly present in microbiology laboratories due to its increasing use for bacterial identification. This study describes a method for detection of carbapenemase activity using MALDI-TOF, which is similar to the reference method: the detection of imipenem hydrolysis using UV spectrometry. PMID:24286119

Hoyos-Mallecot, Y; Cabrera-Alvargonzalez, J J; Miranda-Casas, C; Rojo-Martín, M D; Liebana-Martos, C; Navarro-Marí, J M

2014-04-01

82

Optimization of MALDI-TOF MS detection for enhanced sensitivity of affinity-captured proteins spanning a 100 kDa mass range.  

PubMed

Analysis of complex biological samples by MALDI-TOF mass spectrometry has been generally limited to the detection of low-mass protein (or protein fragment) peaks. We have extended the mass range of MALDI-TOF high-sensitivity detection by an order of magnitude through the combined optimization of instrument parameters, data processing, and sample preparation procedures for affinity capture. WCX, C3, and IMAC magnetic beads were determined to be complementary and most favorable for broad mass range protein profiling. Key instrument parameters for extending mass range included adjustment of the ADC offset and preamplifier filter values of the TOF detector. Data processing was improved by a combination of constant and quadratic down-sampling, preceded by exponential baseline subtraction, to increase sensitivity of signal peaks. This enhancement in broad mass range detection of protein signals will be of direct benefit in MS expression profiling studies requiring full linear range mass detection. PMID:17918874

Gatlin-Bunai, Christine L; Cazares, Lisa H; Cooke, William E; Semmes, Oliver J; Malyarenko, Dariya I

2007-11-01

83

Optimization of MALDI-TOF MS Detection for Enhanced Sensitivity of Affinity-Captured Proteins Spanning a 100 kDa Mass Range  

PubMed Central

Analysis of complex biological samples by MALDI-TOF mass spectrometry has been generally limited to the detection of low-mass protein (or protein fragment) peaks. We have extended the mass range of MALDI-TOF high-sensitivity detection by an order of magnitude through the combined optimization of instrument parameters, data processing, and sample preparation procedures for affinity capture. WCX, C3, and IMAC magnetic beads were determined to be complementary and most favorable for broad mass range protein profiling. Key instrument parameters for extending mass range included adjustment of the ADC offset and preamplifier filter values of the TOF detector. Data processing was improved by a combination of constant and quadratic down-sampling, preceded by exponential baseline subtraction, to increase sensitivity of signal peaks. This enhancement in broad mass range detection of protein signals will be of direct benefit in MS expression profiling studies requiring full linear range mass detection.

Gatlin-Bunai, Christine L.; Cazares, Lisa H.; Cooke, William E.; Semmes, Oliver J.; Malyarenko, Dariya I.

2007-01-01

84

Secondary Metabolite Profiling of Curcuma Species Grown at Different Locations Using GC/TOF and UPLC/Q-TOF MS.  

PubMed

Curcuma, a genus of rhizomatous herbaceous species, has been used as a spice, traditional medicine, and natural dye. In this study, the metabolite profile of Curcuma extracts was determined using gas chromatography-time of flight mass spectrometry (GC/TOF MS) and ultrahigh-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC/Q-TOF MS) to characterize differences between Curcuma aromatica and Curcuma longa grown on the Jeju-do or Jin-do islands, South Korea. Previous studies have performed primary metabolite profiling of Curcuma species grown in different regions using NMR-based metabolomics. This study focused on profiling of secondary metabolites from the hexane extract of Curcuma species. Principal component analysis (PCA) and partial least-squares discriminant analysis (PLS-DA) plots showed significant differences between the C. aromatica and C. longa metabolite profiles, whereas geographical location had little effect. A t-test was performed to identify statistically significant metabolites, such as terpenoids. Additionally, targeted profiling using UPLC/Q-TOF MS showed that the concentration of curcuminoids differed depending on the plant origin. Based on these results, a combination of GC- and LC-MS allowed us to analyze curcuminoids and terpenoids, the typical bioactive compounds of Curcuma, which can be used to discriminate Curcuma samples according to species or geographical origin. PMID:25000465

Lee, Jueun; Jung, Youngae; Shin, Jeoung-Hwa; Kim, Ho Kyoung; Moon, Byeong Cheol; Ryu, Do Hyun; Hwang, Geum-Sook

2014-01-01

85

Quantitation of irbesartan and major proteins in human plasma by mass spectrometry with time-of-flight analyzer  

Microsoft Academic Search

A simple matrix-assisted laser desorption\\/ionization time-of-flight mass spectrometry (MALDI-TOF MS) method was developed to analyze irbesartan in human plasma. Irbesartan is a kind of angiotensin II receptor blocker (ARB) and is used as an antihypertensive drug. MALDI-TOF MS is a rare application for clinical drug analysis in human plasma. After simple micro-liquid–liquid extraction, irbesartan-containing supernatant was spotted on a target

Chi-Yu Lu; Chia-Hsien Feng

2011-01-01

86

Comparison of hydrolysis products of AlCl3·6H2O in different concentrations by electrospray ionization time of flight mass spectrometer (ESI TOF MS)  

Microsoft Academic Search

Hydrolysis of 0.100, 0.010, and 0.001?mol?L aqueous solutions of AlCl3·6H2O, each at two pH values ranging from 3.27 to 7.00, was compared by electrospray ionization time-of-flight mass spectrometry. The differences between 4?h and 14?day aged solutions were also studied. Various charges and compositions for species of the same size were observed. At lower pH values, dimeric and trimeric aluminium oxo-hydroxo-complexes

Arja T. Sarpola; Vesa K. Hietapelto; Jorma E. Jalonen; Jukka Jokela; Jaakko H. Rämö

2006-01-01

87

Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry for the Identification of Clinically Relevant Bacteria  

PubMed Central

Background Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) allows rapid and reliable identification of microorganisms, particularly clinically important pathogens. Methodology/Principal Findings We compared the identification efficiency of MALDI-TOF MS with that of Phoenix®, API® and 16S ribosomal DNA sequence analysis on 1,019 strains obtained from routine diagnostics. Further, we determined the agreement of MALDI-TOF MS identifications as compared to 16S gene sequencing for additional 545 strains belonging to species of Enterococcus, Gardnerella, Staphylococcus, and Streptococcus. For 94.7% of the isolates MALDI-TOF MS results were identical with those obtained with conventional systems. 16S sequencing confirmed MALDI-TOF MS identification in 63% of the discordant results. Agreement of identification of Gardnerella, Enterococcus, Streptococcus and Staphylococcus species between MALDI-TOF MS and traditional method was high (Crohn's kappa values: 0.9 to 0.93). Conclusions/Significance MALDI-TOF MS represents a rapid, reliable and cost-effective identification technique for clinically relevant bacteria.

Benagli, Cinzia; Rossi, Viviana; Dolina, Marisa; Tonolla, Mauro; Petrini, Orlando

2011-01-01

88

Mass spectrometry of nanodiamonds.  

PubMed

Detonation nanodiamonds (NDs) were studied by time-of-flight mass spectrometry (TOF MS). The formation of singly charged carbon clusters, C(n) (+), with groups of clusters at n = 1-35, n approximately 160-400 and clusters with n approximately 8000 was observed. On applying either high laser energy or ultrasound, the position and intensity of the maxima change and a new group of clusters at n approximately 70-80 is formed. High carbon clusters consist of an even number of carbons while the percentage of odd-numbered clusters is quite low (< or =5-10%). On increasing the laser energy, the maximum of ionization (at n approximately 200 carbons) is shifted towards the lower m/z values. It is suggested that this is mainly due to the disaggregation of the original NDs. However, the partial destruction of NDs is also possible. The carbon clusters (n approximately 2-35) are partially hydrogenated and the average value of the hydrogenation was 10-30%. Trace impurities in NDs like Li, B, Fe, and others were detected at high laser energy. Several matrices for ionizing NDs were examined and NDs themselves can also be used as a matrix for the ionization of various organic compounds. When NDs were used as a matrix for gold nanoparticles, the formation of various gold carbides Au(m)C(n) was detected and their stoichiometry was determined. It was demonstrated that TOF MS can be used advantageously to analyze NDs, characterize their size distribution, aggregation, presence of trace impurities and surface chemistry. PMID:19280609

Houska, Jan; Panyala, Nagender Reddy; Peña-Méndez, Eladia Maria; Havel, Josef

2009-04-01

89

Detection of Murine Toxoplasmosis Using Magnetic Bead-Based Serum Peptide Profiling by MALDI-TOF MS  

PubMed Central

Abstract Establishment of a rapid, highly specific, and accurate method for diagnosis of Toxoplasma gondii infection is essential to control and prevent zoonotic toxoplasmosis. In this study, a novel diagnostic strategy using magnetic bead-based serum peptide profiling by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) was developed. The serum peptides (samples I, II, and III) from T. gondii RH strain-infected mice at days 3, 6, and 9 post-infection (p.i.), and healthy mice were enriched by the optimized magnetic bead-based hydrophobic interaction (MB-HIC8). The mass spectrograms were acquired by MALDI-TOF MS, and analyzed by ClinProTools bioinformatics software from Bruker Daltonics. The diagnostic models from T. gondii RH-infected serum peptide profiling of samples I, II, and III were produced by genetic algorithms, and verified by cross-validation. The sample II model could correctly recognize T. gondii RH strain infection in mice at days 3, 6, and 9 p.i. with a sensitivity of 91.1% and a specificity of 96.7%., and also detect T. gondii ME49 strain-infected serum samples at days 3, 6, 9, and 12 p.i. with a sensitivity of 91.7%. The results of the present study suggest that serum peptide profiling by MALDI-TOF MS is a novel potential tool for the clinical diagnosis of acute T. gondii infection.

Li, Jiping; Jin, Hongtao; Li, Lixia; Shang, Limin; Zhao, Yongkun; Wei, Feng; Liu, Yanjing; Qian, Jun

2012-01-01

90

Spontaneous-Desorption Ionizer for a TOF-MS  

NASA Technical Reports Server (NTRS)

A time-of-flight mass spectrometer (TOF-MS) like the one mentioned in the immediately preceding article has been retrofitted with an ionizer based on a surface spontaneous-desorption process. This ionizer includes an electron multiplier in the form of a microchannel plate (MCP). Relative to an ionizer based on a hot-filament electron source, this ionizer offers advantages of less power consumption and greater mechanical ruggedness. The current density and stability characteristics of the electron emission of this ionizer are similar to those of a filament-based ionizer. In tests of various versions of this ionizer in the TOF-MS, electron currents up to 100 nA were registered. Currents of microamperes or more - great enough to satisfy requirements in most TOFMS applications - could be obtained by use of MCPs different from those used in the tests, albeit at the cost of greater bulk. One drawback of this ionizer is that the gain of the MCP decreases as a function of the charge extracted thus far; the total charge that can be extracted over the operational lifetime is about 1 coulomb. An MCP in the ion-detector portion of the TOF-MS is subject to the same limitation.

Schultz, J. Albert

2006-01-01

91

Identification of bio-active metabolites of gentiopicroside by UPLC/Q-TOF MS and NMR.  

PubMed

Gentiopicroside (GPS), the main bioactive component in Gentiana scabra Bge., has attracted our attention owing to its high bioactivity, especially the treatment of hepatobiliary disorders. The aglycone form of GPS, a typical secoiridoid glycoside, is considered to be more readily absorbed than its parent drug. This study aimed to identify and characterize the metabolites after GPS incubated with ?-glucosidase in buffer solution at 37°C. Samples of biotransformed solution were collected and analyzed by ultraperformance liquid chromatography (UPLC)/quadrupole-time-of-flight mass spectrometry (Q-TOF MS). A total of four metabolites were detected: two were isolated and elucidated by preparative-HPLC and NMR techniques, and one of those four is reported for the first time. The mass spectral fragmentation pattern and accurate masses of metabolites were established on the basis of UPLC/Q-TOF MS analysis. Structure elucidation of metabolites was achieved by comparing their fragmentation pattern with that of the parent drug. A fairly possible metabolic pathway of GPS by ?-glucosidase was proposed. The hepatoprotective activities of metabolites M1 and M2 were investigated and the results showed that their hepatoprotective activities were higher than that of parent drug. Our results provided a meaningful basis for discovering lead compounds from biotransformation related to G. scabra Bge. in traditional Chinese medicine. PMID:23733682

Zeng, Wenliang; Han, Han; Tao, Yanyan; Yang, Li; Wang, Zhengtao; Chen, Kaixian

2013-09-01

92

Determination of molecular mass distribution of silicone oils by supercritical fluid chromatography, matrix-assisted laser desorption ionization time-of-flight mass spectrometry and their off-line combination.  

PubMed

Silicone oil samples were characterized by supercritical fluid chromatography (SFC), matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI--TOF MS), and their off-line combination. SFC was used to separate samples of silicone oils on micropacked capillary columns. The fractions for the identification studies were obtained from SFC runs at defined time intervals, when the restrictor was pulled out from the chromatographic flame ionization detector (FID) and inserted into a glass vial with acetone. MALDI--TOF MS was used for the identification of individual oligomers in the fractions separated. The molecular mass distributions determined based on SFC and MALDI--TOF MS measurements were compared. From this comparison, it follows that the results are in good agreement. However, certain differences were observed: MALDI--TOF MS was capable of detecting somewhat larger oligomers than the SFC-FID, but the lower molecular mass oligomers were not present in the MALDI spectra. Differences in the region of lower molecular masses can be explained by evaporation of the more volatile low molecular mass oligomers resulting from heating of the sample during the MALDI--TOF MS measurements as a result of the absorption of the laser shot energy. The fact that no high mass discrimination effects of the MALDI--TOF MS measurements, compared with SFC, were observed is very promising for further applications of MALDI--TOF MS in characterizing synthetic polymers of moderate polydispersity. PMID:11473399

Chmelík, J; Planeta, J; Rehulka, P; Chmelík, J

2001-07-01

93

Characterization of oligomeric polypropyleneglycol acrylate by GC, SFC and MALDI-TOF-MS.  

PubMed

Polypropyleneglycol acrylate (PGA), one of the typical acrylic oligomers manufactured industrially, was comprehensively characterized by gas chromatography (GC), supercritical fluid chromatography (SFC) and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS). The homologous series of polypropyleneglycol diacrylate (DA), polypropyleneglycol monoacrylate (MA), and unreacted polypropyleneglycol (PG) were observed as Na adducts in the MALDI-MS spectra of the PGA samples. The relative intensities of these peaks reflect the distributions of the homologues, although their accurate quantification was generally difficult because of change in the ionization efficiency depending on the chemical structure and the molecular weight of the species. On the other hand, the DA and the MA homologues were observed in the chromatograms obtained by SFC in a temperature-programming mode, while the PG homologues were not detected under the given SFC conditions using UV detection. Here, the determination of the degree of polymerization of each component in the chromatograms was accomplished through SFC fractionation for the corresponding peaks, followed again by MALDI-TOF-MS measurement. Furthermore, most of the components in the PGA samples were almost completely separated in the resulting gas chromatograms, and their unequivocal assignments were made also using the retention data on the gas chromatograms of the SFC fractions. As for the quantitative analysis, the relative abundances among DA, MA and PG for lower degrees of polymerization can be easily calculated based on the observed gas chromatograms, whereas the distribution of DA and MA can be estimated from the observed SFC data even for the relatively higher molecular weight fractions, which are generally difficult to determine accurately by GC because of their lower volatility. These results demonstrated that even the complex PGA samples were able to be characterized in detail by using GC, SFC and MALDI-TOF-MS complementarily. PMID:11918185

Matsunaga, Morikatsu; Matsushima, Yoshiaki; Yokoi, Hiroaki; Ohtani, Hajime; Tsuge, Shin

2002-03-01

94

Quantification of thymosin ? 4 in human cerebrospinal fluid using matrix-assisted laser desorption\\/ionization time-of-flight mass spectrometry  

Microsoft Academic Search

Matrix-assisted laser desorption\\/ionization time-of-flight mass spectrometry (MALDI–TOF–MS) has been applied to the analysis of a wide range of biomolecules. To date, there are two specific areas of application where MALDI–TOF–MS is viewed as impractical: analysis of low-mass analytes and relative quantitative applications. However, these limitations can be overcome and quantification can be routine. Increased levels of thymosin ?4 (TB4) have

Elena Urso; Maria Le Pera; Sabrina Bossio; Teresa Sprovieri; Antonio Qualtieri

2010-01-01

95

Rapid MALDI-TOF mass spectrometry identification of Leptospira organisms.  

PubMed

Leptospirosis is a worldwide deadly zoonotic disease. Accurate identification of the causative Leptospira spp. spirochetes ascertains the pathogenic status of the isolates, identifies potential source of infection and recognises outbreaks. Species identification is currently based on technically demanding, time and resources consuming serological and molecular methods. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) recently emerged as a first-line method for the accurate identification of bacteria, yet no data issued for Leptospira spp. We investigated the potential of MALDI-TOF-MS for the rapid identification of Leptospira isolates. Starting from a 10(5)organisms/mL suspension, MALDI-TOF-MS yielded an unique protein profile for each one of 19 Leptospira species reference isolates with a 100% reproducibility over 12 repeats, allowing to create a Leptopsira database. MALDI-TOF-MS further accurately identified 20/21 additional reference isolates representative of various serogroups at the species level as Leptospira interrogans (n=12), Leptospira kirschneri (n=5), Leptospira borgpetersenii (n=3), Leptospira noguchii (n=1) with identification score value of 2-2.5. Furthermore, six clinical isolates previously identified by rpoB sequencing, were correctly identified by MALDI-TOF-MS as L. interrogans (n=5) and L. borgpetersenii (n=1) with identification score value of 2-2.6. Identification was achieved in 40 min starting from the Leptospira suspension. MALDI-TOF-MS could complement serological and sequencing-based methods for the first line, rapid identification of Leptospira isolates in the clinical microbiology laboratory. PMID:22386673

Djelouadji, Zoheira; Roux, Véronique; Raoult, Didier; Kodjo, Angeli; Drancourt, Michel

2012-07-01

96

Development of a Direct Headspace Collection Method from Arabidopsis Seedlings Using HS-SPME-GC-TOF-MS Analysis  

PubMed Central

Plants produce various volatile organic compounds (VOCs), which are thought to be a crucial factor in their interactions with harmful insects, plants and animals. Composition of VOCs may differ when plants are grown under different nutrient conditions, i.e., macronutrient-deficient conditions. However, in plants, relationships between macronutrient assimilation and VOC composition remain unclear. In order to identify the kinds of VOCs that can be emitted when plants are grown under various environmental conditions, we established a conventional method for VOC profiling in Arabidopsis thaliana (Arabidopsis) involving headspace-solid-phase microextraction-gas chromatography-time-of-flight-mass spectrometry (HS-SPME-GC-TOF-MS). We grew Arabidopsis seedlings in an HS vial to directly perform HS analysis. To maximize the analytical performance of VOCs, we optimized the extraction method and the analytical conditions of HP-SPME-GC-TOF-MS. Using the optimized method, we conducted VOC profiling of Arabidopsis seedlings, which were grown under two different nutrition conditions, nutrition-rich and nutrition-deficient conditions. The VOC profiles clearly showed a distinct pattern with respect to each condition. This study suggests that HS-SPME-GC-TOF-MS analysis has immense potential to detect changes in the levels of VOCs in not only Arabidopsis, but other plants grown under various environmental conditions.

Kusano, Miyako; Iizuka, Yumiko; Kobayashi, Makoto; Fukushima, Atsushi; Saito, Kazuki

2013-01-01

97

Efficient Analysis of Non-Polar Environmental Contaminants by MALDI-TOF MS with Graphene as Matrix  

NASA Astrophysics Data System (ADS)

In this Application Note, we describe, for the first time, the rapid analysis of hydrophobic compounds present in environmental contaminants, which includes polycyclic aromatic hydrocarbons (PAHs) and estrogen, by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) with the use of graphene as matrix. MALDI-TOF MS with conventional matrix has limitations in analyzing low-polarity compounds owing to their difficulty in ionization. We demonstrate that compared with conventional matrix, graphene displays higher desorption/ionization efficiencies for PAHs, and no fragment ions are observed. The method also holds potential in quantitative analysis. In addition, the ionization signal increases with the increasing number of benzene rings in the PAHs, suggesting that graphene binds to PAHs via ?-? stacking interactions. Furthermore, graphene as adsorbent for solid-phase extraction of coronene from river water sample displays good performance with a detection limit of 10-7 M. This work provides a novel and convenient method for analyzing low-polarity environmental contaminants by MALDI-TOF MS.

Zhang, Jing; Dong, Xiaoli; Cheng, Jinsheng; Li, Jinghong; Wang, Yinsheng

2011-07-01

98

MALDI-TOF/MS fingerprinting of triacylglycerols (TAGs) in olive oils produced in the Israeli Negev desert.  

PubMed

Triacylglycerols (TAGs), composed of three esterified fatty acids with an attached glycerol backbone, are the main component of vegetable oil (approximately 95%) and an important source of energy and nutrition for humans, so their compositional analysis merits extensive interest. Intact TAG composition of oil in native form is highly important, rather than the fatty acid profile itself. This paper reports the analysis of the TAG profile of olive oils produced from the six common olive cultivars grown in the Negev desert of Israel (Barnea, Souri, Arbequina, Picual, Leccino, and Koroneiki) together with the content of some additional common oil quality parameters closely associated with TAG composition and integrity. Matrix-assisted laser ionization-desorption time-of-flight/mass spectrometry (MALDI-TOF/MS) fingerprintings were employed for TAG profiling. With 2,5-dihydroxybenzoic acid (DHB), MALDI-TOF/MS was able to fingerprint the intact TAG profiles in olive oils in a fast and easy manner without any derivatization. Triolein (31.53%) was found to be the main intact TAG followed by dioleoyl-palmitoyl (23.06%) and dioleoyl-linoleoyl (14.31%). MALDI-TOF/MS also enabled calculation of the main fatty acids and their compositions in a simple manner from the TAG profiles; the results are found to be very similar to conventional methods determined by GC and HPLC. Average free fatty acids and peroxide value were found to be less than 0.8% and 10 mequiv of O(2)/kg of oil, respectively, in all of the tested oils. Relatively high levels of tocopherols (av = 325 microg/kg) and phytosterols (av = 2375 mg/kg) were found. This study demonstrates MALDI-TOF/MS technology as an easy and fast methodology for TAG and fatty acid profile analysis in olive oils. Additionally, this study also shows the high levels of tocopherols and phytosterols in the olive oils produced from the common cultivars grown in the Israeli Negev desert. PMID:19199592

Chapagain, Bishnu P; Wiesman, Zeev

2009-02-25

99

Correlations between blood glucose and breath components from portable gas sensors and PTR-TOF-MS.  

PubMed

Acetone is one of the most abundant volatile compounds in the human breath and might be important for monitoring diabetic patients. Here, a portable acetone sensor consisting of flame-made, nanostructured, Si-doped WO3 sensing films was used to analyse the end tidal fraction of the breath (collected in Tedlar bags) from eight healthy volunteers after overnight fasting (morning) and after lunch (afternoon). After breath sampling, the gaseous components were also analysed by proton transfer reaction time-of-flight mass spectrometry (PTR-TOF-MS), and each person's blood glucose level was measured. The portable sensor accurately detected the presence of acetone with fast response/recovery times (<12 s) and a high signal-to-noise ratio. Statistical analysis of the relationship between the PTR-TOF-MS measurements of breath gases (e.g., acetone, isoprene, ethanol and methanol), sensor response and the blood glucose level was performed for both sampling periods. The best correlations were found after overnight fasting (morning): in particular, between blood glucose level and breath acetone (Pearson's 0.98 and Spearman's 0.93). Whereas the portable sensor response correlated best with the blood glucose (Pearson's 0.96 and Spearman's 0.81) and breath acetone (Pearson's 0.92 and Spearman's 0.69). PMID:23959908

Righettoni, M; Schmid, A; Amann, A; Pratsinis, S E

2013-09-01

100

Profiling the ginsenosides of three ginseng products by LC-Q-TOF/MS.  

PubMed

Ginseng is a well-known herbal medicine that has been gaining increasingly popularity as a potential chemopreventive agent. In traditional Chinese medicine practice, white ginseng (WG), red ginseng (RG), and dali ginseng (DG) are 3 different ginseng-processed products used for different purposes. Although the morphological appearance and some constituents contained in these ginseng products are similar, their pharmacological activities are significantly different due to the varied types and quantity of ginsenosides in each product. In the present study, a practical method based on rapid liquid chromatography coupled with quadrupole time of flight mass spectrometry (LC-Q-TOF/MS) was developed to identify the chemical profiles of ginsenosides in these 3 ginseng products. The results demonstrated that a total of 55, 53, and 43 compounds were unambiguously assigned or tentatively identified in DG, WG, and RG samples, respectively. The featured compounds are mainly malonyl ginsenosides in WG, and decarboxyl products of mal-ginsenosides and the dehydrated compounds from polar ginsenosides were characteristic in RG, while DG contain some characteristic components present both in WG and RG. We presume that heating processing is the major factor affecting the chemical profile of ginseng products. The difference of chemical information revealed by LC-Q-TOF/MS could be used to discriminate the WG, RG, and DG samples. PMID:23550959

Chu, Chu; Xu, Shaojing; Li, Xingnuo; Yan, Jizhong; Liu, Li

2013-05-01

101

Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry Identification of Yeasts Is Contingent on Robust Reference Spectra  

Microsoft Academic Search

BackgroundMatrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) for yeast identification is limited by the requirement for protein extraction and for robust reference spectra across yeast species in databases. We evaluated its ability to identify a range of yeasts in comparison with phenotypic methods.MethodsMALDI-TOF MS was performed on 30 reference and 167 clinical isolates followed by prospective examination

Angie Pinto; Catriona Halliday; Melissa Zahra; Sebastian van Hal; Tom Olma; Krystyna Maszewska; Jonathan R. Iredell; Wieland Meyer; Sharon C.-A. Chen; Markus M. Heimesaat

2011-01-01

102

Use of Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry for Caspofungin Susceptibility Testing of Candida and Aspergillus Species  

PubMed Central

Matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) was evaluated for testing susceptibility to caspofungin of wild-type and fks mutant isolates of Candida and Aspergillus. Complete essential agreement was observed with the CLSI reference method, with categorical agreement for 94.1% of the Candida isolates tested. Thus, MALDI-TOF MS is a reliable and accurate method to detect fungal isolates with reduced caspofungin susceptibility.

De Carolis, Elena; Vella, Antonietta; Florio, Ada R.; Posteraro, Patrizia; Perlin, David S.; Posteraro, Brunella

2012-01-01

103

A comparative study of amino acid measurement in leaf extracts by gas chromatography-time of flight-mass spectrometry and high performance liquid chromatography with fluorescence detection  

Microsoft Academic Search

Gas chromatography coupled to time-of-flight mass spectrometry (GC-TOF-MS) has become a promising technique for simultaneous\\u000a and rapid analysis of small metabolites in complex mixtures. The aim of this work was to establish the quantitative nature\\u000a of the information generated by amino acid analysis of crude leaf extracts using GC-TOF-MS. Dried aliquots of methanol\\/water\\u000a extracts of Arabidopsis leaves were analysed in

Graham Noctor; Gaëlle Bergot; Caroline Mauve; Dorothée Thominet; Caroline Lelarge-Trouverie; Jean-Louis Prioul

2007-01-01

104

Angiotensin II-acetylcholine noncovalent complexes analyzed with MALDI-ion mobility-TOF MS.  

PubMed

Matrix-assisted laser desorption ionization-ion mobility-orthogonal time-of-flight mass spectrometry (MALDI-IM oTOF MS) is a new technique that allows laser desorbed ion to be preseparated on the basis of their shape prior to mas analysis. Using this instrument, we tested the postulate that addition of a quaternary ammonium compound such as acetylcholine to the model phosphorylated peptide angio tensin II would enhance its detection by MALDI in two ways. First of all, the acetylcholine-peptide complex could ionize more efficiently than the bare phosphopeptide. Furthermore the ion mobility could separate the complex ion on the basis of its charge/volume from isobaric interferences, which would otherwise limit detection sensitivity. PMID:12901606

Woods, Amina S; Fuhrer, Katrin; Gonin, Marc; Egan, Tom; Ugarov, Michael; Gillig, Kent J; Schultz, J Albert

2003-03-01

105

Advances in quantitative hepcidin measurements by time-of-flight mass spectrometry  

Microsoft Academic Search

Assays for the detection of the iron regulatory hormone hepcidin in plasma or urine have not yet been widely available, whereas quantitative comparisons between hepcidin levels in these different matrices were thus far even impossible due to technical restrictions. To circumvent these limitations, we here describe several advances in time-of flight mass spectrometry (TOF MS), the most important of which

Dorine W. Swinkels; Domenico Girelli; Coby Laarakkers; Joyce Kroot; Natascia Campostrini; Erwin H. J. M. Kemna; Harold Tjalsma

2008-01-01

106

High-Throughput Identification of Bacteria and Yeast by Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry in Conventional Medical Microbiology Laboratories ?  

PubMed Central

Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) is suitable for high-throughput and rapid diagnostics at low costs and can be considered an alternative for conventional biochemical and molecular identification systems in a conventional microbiological laboratory. First, we evaluated MALDI-TOF MS using 327 clinical isolates previously cultured from patient materials and identified by conventional techniques (Vitek-II, API, and biochemical tests). Discrepancies were analyzed by molecular analysis of the 16S genes. Of 327 isolates, 95.1% were identified correctly to genus level, and 85.6% were identified to species level by MALDI-TOF MS. Second, we performed a prospective validation study, including 980 clinical isolates of bacteria and yeasts. Overall performance of MALDI-TOF MS was significantly better than conventional biochemical systems for correct species identification (92.2% and 83.1%, respectively) and produced fewer incorrect genus identifications (0.1% and 1.6%, respectively). Correct species identification by MALDI-TOF MS was observed in 97.7% of Enterobacteriaceae, 92% of nonfermentative Gram-negative bacteria, 94.3% of staphylococci, 84.8% of streptococci, 84% of a miscellaneous group (mainly Haemophilus, Actinobacillus, Cardiobacterium, Eikenella, and Kingella [HACEK]), and 85.2% of yeasts. MALDI-TOF MS had significantly better performance than conventional methods for species identification of staphylococci and genus identification of bacteria belonging to HACEK group. Misidentifications by MALDI-TOF MS were clearly associated with an absence of sufficient spectra from suitable reference strains in the MALDI-TOF MS database. We conclude that MALDI-TOF MS can be implemented easily for routine identification of bacteria (except for pneumococci and viridans streptococci) and yeasts in a medical microbiological laboratory.

van Veen, S. Q.; Claas, E. C. J.; Kuijper, Ed J.

2010-01-01

107

Detector response in time-of-flight mass spectrometry at high pulse repetition frequencies  

NASA Technical Reports Server (NTRS)

Dead time effects in chevron configured dual microchannel plates (MCPs) are investigated. Response times are determined experimentally for one chevron-configured dual MCP-type detector and two discrete dynode-type electron multipliers with 16 and 23 resistively divided stages. All of these detectors are found to be suitable for time-of-flight mass spectrometry (TOF MS), yielding 3-6-ns (FWHM) response times triggered on a single ion pulse. It is concluded that, unless there are viable solutions to overcome dead time disadvantages for continuous dynode detectors, suitable discrete dynode detectors for TOF MS appear to have a significant advantage for high repetition rate operation.

Gulcicek, Erol E.; Boyle, James G.

1993-01-01

108

Metabolomics of transgenic maize combining Fourier transform-ion cyclotron resonance-mass spectrometry, capillary electrophoresis-mass spectrometry and pressurized liquid extraction  

Microsoft Academic Search

In this work, the potential of combining capillary electrophoresis-time-of-flight-mass spectrometry (CE-TOF-MS) and Fourier transform-ion cyclotron resonance-mass spectrometry (FT-ICR-MS) for metabolomics of genetically modified organisms (GMOs) is demonstrated. Thus, six different varieties of maize, three of them transgenic (PR33P66 Bt, Tietar Bt and Aristis Bt) and their corresponding isogenic lines (PR33P66, Tietar and Aristis) grown under the same field conditions, were

Carlos Leon; Irene Rodriguez-Meizoso; Marianna Lucio; Virginia Garcia-Cañas; Elena Ibañez; Philippe Schmitt-Kopplin; Alejandro Cifuentes

2009-01-01

109

Mass spectrometry.  

NASA Technical Reports Server (NTRS)

Review of the current state of mass spectrometry, indicating its unique importance for advanced scientific research. Mass spectrometry applications in computer techniques, gas chromatography, ion cyclotron resonance, molecular fragmentation and ionization, and isotope labeling are covered. Details are given on mass spectrometry applications in bio-organic chemistry and biomedical research. As the subjects of these applications are indicated alkaloids, carbohydrates, lipids, terpenes, quinones, nucleic acid components, peptides, antibiotics, and human and animal metabolisms. Particular attention is given to the mass spectra of organo-inorganic compounds, inorganic mass spectrometry, surface phenomena such as secondary ion and electron emission, and elemental and isotope analysis. Further topics include mass spectrometry in organic geochemistry, applications in geochronology and cosmochemistry, and organic mass spectrometry.

Burlingame, A. L.; Johanson, G. A.

1972-01-01

110

Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry as an Alternative to 16S rRNA Gene Sequencing for Identification of Difficult-To-Identify Bacterial Strains?†  

PubMed Central

Conventional methods are sometimes insufficient to identify human bacterial pathogens, and alternative techniques, often molecular, are required. Matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) identified with a valid score 45.9% of 410 clinical isolates from 207 different difficult-to-identify species having required 16S rRNA gene sequencing. MALDI-TOF MS might represent an alternative to 16S rRNA gene sequencing.

Bizzini, A.; Jaton, K.; Romo, D.; Bille, J.; Prod'hom, G.; Greub, G.

2011-01-01

111

Identification of serum biomarkers for lung cancer using magnetic bead-based SELDI-TOF-MS  

Microsoft Academic Search

Aim:To identify novel serum biomarkers for lung cancer diagnosis using magnetic bead-based surface-enhanced laser desorption\\/ionization time-of-flight mass spectrum (SELDI-TOF-MS).Methods:The protein fractions of 121 serum specimens from 30 lung cancer patients, 30 pulmonary tuberculosis patients and 33 healthy controls were enriched using WCX magnetic beads and subjected to SELDI-TOF-MS. The spectra were analyzed using Bio-marker Wizard version 3.1.0 and Biomarker Patterns

Qi-bin Song; Wei-guo Hu; Peng Wang; Yi Yao; Hua-zong Zeng

2011-01-01

112

MALDI-TOF MS for the identification of veterinary non-C. neoformans-C. gattii Cryptococcus spp. isolates from Italy.  

PubMed

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) offers an effective alternative to phenotypic and molecular methods for the rapid identification of microorganisms. Our aim in this study was to create an in-house library for a set of strains of nine uncommonly reported human and animal cryptococcal species, including Cryptococcus adeliensis, C. albidosimilis, C. albidus, C. aureus, C. carnescens, C. laurentii, C. magnus, C. victoriae and C. uniguttulatus, and to use this library to make timely and correct identifications using MALDI-TOF MS for use in routine laboratory diagnostics. Protein extracts obtained via the formic acid extraction method of 62 veterinary non-C. neoformans-C. gattii cryptococcal isolates were studied. The obtained mass spectra correctly grouped all 62 studied isolates according to species identification previously obtained by internal transcribe spacer sequence analysis. The in-house database was than exported and successfully uploaded to the Microflex LT (Maldi Biotyper; Bruker Daltonics) instrument at a different diagnostic laboratory in Italy. Scores >2.7 obtained from isolates reanalyzed in the latter laboratory supported the high reproducibility of the method. The possibility of creating and transferring an in-house library adds to the usefulness MALDI-TOF MS an important tool for the rapid and inexpensive identification of pathogenic and saprophytic fungi as required for differential diagnosis of human and animal mycoses. PMID:24951721

Danesi, Patrizia; Drigo, Ilenia; Iatta, Roberta; Firacative, Carolina; Capelli, Gioia; Cafarchia, Claudia; Meyer, Wieland

2014-08-01

113

Early Diagnosis of Irkut Virus Infection Using Magnetic Bead-Based Serum Peptide Profiling by MALDI-TOF MS in a Mouse Model  

PubMed Central

Early diagnosis is important for the prompt post-exposure prophylaxis of lyssavirus infections. To diagnose Irkut virus (IRKV) infection during incubation in mice, a novel method using magnetic bead-based serum peptide profiling by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been established. For this test, serum peptides were concentrated by adsorption to and elution from the magnetic bead-based weak cation ion exchanger. Mass spectrograms obtained by MALDI-TOF MS were analyzed using ClinProTools bioinformatics software. Construction of the diagnostic model was performed using serum samples from mice infected with IRKV and rabies virus (RABV) BD06, Flury-LEP, and SRV9 (as controls). The method accurately diagnosed sera 2, 4 and 8 days after IRKV and RABV infections. The sensitivity, specificity, and total accuracy of diagnosis were 86.7%, 95.2%, and 92.9%, respectively. However, IRKV could not be differentiated from RABV 1 day after infection. The results of the present study indicate that serum peptide profiling by MALDI-TOF MS is a promising technique for the early clinical diagnosis of lyssavirus infections and needs to be further tested in humans and farm animals.

Li, Nan; Liu, Ye; Hao, Zhuo; Zhang, Shoufeng; Hu, Rongliang; Li, Jiping

2014-01-01

114

MALDI TOF MS profiling of bacteria at the strain level: a review.  

PubMed

Since the advent of the use of matrix-assisted laser desorption/ionization (MALDI) time-of-flight mass spectrometry (TOF MS) as a tool for microbial characterization, efforts to increase the taxonomic resolution of the approach have been made. The rapidity and efficacy of the approach have suggested applications in counter-bioterrorism, prevention of food contamination, and monitoring the spread of antibiotic-resistant bacteria. Strain-level resolution has been reported with diverse bacteria, using library-based and bioinformatics-enabled approaches. Three types of characterization at the strain level have been reported: strain categorization, strain differentiation, and strain identification. Efforts to enhance the library-based approach have involved sample pre-treatment and data reduction strategies. Bioinformatics approaches have leveraged the ever-increasing amount of publicly available genomic and proteomic data to attain strain-level characterization. Bioinformatics-enabled strategies have facilitated strain characterization via intact biomarker identification, bottom-up, and top-down approaches. Rigorous quantitative and advanced statistical analyses have fostered success at the strain level with both approaches. Library-based approaches can be limited by effects of sample preparation and culture conditions on reproducibility, whereas bioinformatics-enabled approaches are typically limited to bacteria, for which genetic and/or proteomic data are available. Biological molecules other than proteins produced in strain-specific manners, including lipids and lipopeptides, might represent other avenues by which strain-level resolution might be attained. Immunological and lectin-based chemistries have shown promise to enhance sensitivity and specificity. Whereas the limits of the taxonomic resolution of MALDI TOF MS profiling of bacteria appears bacterium-specific, recent data suggest that these limits might not yet have been reached. PMID:22996584

Sandrin, Todd R; Goldstein, Jason E; Schumaker, Stephanie

2013-01-01

115

Relative Quantitation of Glycopeptides Based on Stable Isotope Labeling Using MALDI-TOF MS.  

PubMed

We have developed an effective, sensitive method for quantitative glycopeptide profiling using stable isotope labeling and MALDI-TOF mass spectrometry (MS). In this study, we synthesized benzoic acid-d0 N-succinimidyl ester (BzOSu) and benzoic acid-d5 N-succinimidyl ester (d-BzOSu) as light and heavy isotope reagents for stable isotope quantification for the comparative analysis of glycopeptides. Using this approach provided enhanced ionization efficiency in both positive and negative modes by MALDI-TOF MS. These reagents were quantitatively reacted with glycopeptides from human serum IgG (hIgG) at a wide range of concentrations; the labeling efficiency of the glycopeptides showed high reproducibility and a good calibration curve was obtained. To demonstrate the practical utility of this approach, we characterized the structures of glycopeptides from hIgG and from IgG1 produced by myeloma plasma. The glycopeptides were quantitatively analyzed by mixing Bz-labeled IgG1 glycopeptides with d-Bz-labeled hIgG glycopeptides. Glycan structural identification of the hIgG glycopeptides was demonstrated by combining the highly specific recognition of endo-?-N-acetyl glucosaminidases from Streptococcus pyogenes (endoS) or from Streptococcus pneumoniae (endo-D) with MALDI-TOF MS analysis. The obtained data revealed the glycan profile and the ratio of glycan structural isomers containing a galactosylated extension on IgG1, IgG2 and IgG3 glycopetides. PMID:25010467

Kurogochi, Masaki; Amano, Junko

2014-01-01

116

MALDI-TOF MS versus VITEK 2 ANC card for identification of anaerobic bacteria  

PubMed Central

Background Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) is an accurate, rapid and inexpensive technique that has initiated a revolution in the clinical microbiology laboratory for identification of pathogens. The Vitek 2 anaerobe and Corynebacterium (ANC) identification card is a newly developed method for identification of corynebacteria and anaerobic species. The aim of this study was to evaluate the effectiveness of the ANC card and MALDI-TOF MS techniques for identification of clinical anaerobic isolates. Methods Five reference strains and a total of 50 anaerobic bacteria clinical isolates comprising ten different genera and 14 species were identified and analyzed by the ANC card together with Vitek 2 identification system and Vitek MS together with version 2.0 database respectively. 16S rRNA gene sequencing was used as reference method for accuracy in the identification. Results Vitek 2 ANC card and Vitek MS provided comparable results at species level for the five reference strains. Of 50 clinical strains, the Vitek MS provided identification for 46 strains (92%) to the species level, 47 (94%) to genus level, one (2%) low discrimination, two (4%) no identification and one (2%) misidentification. The Vitek 2 ANC card provided identification for 43 strains (86%) correct to the species level, 47 (94%) correct to the genus level, three (6%) low discrimination, three (6%) no identification and one (2%) misidentification. Conclusions Both Vitek MS and Vitek 2 ANC card can be used for accurate routine clinical anaerobe identification. Comparing to the Vitek 2 ANC card, Vitek MS is easier, faster and more economic for each test. The databases currently available for both systems should be updated and further developed to enhance performance.

Li, Yang; Gu, Bing; Xia, Wenying; Fan, Kun; Mei, Yaning; Huang, Peijun; Pan, Shiyang

2014-01-01

117

GyrB sequence analysis and MALDI-TOF MS as identification tools for plant pathogenic Clavibacter.  

PubMed

The bacterial genus Clavibacter has only one species, Clavibacter michiganensis, containing five subspecies. All five are plant pathogens, among which three are recognized as quarantine pests (mentioned on the EPPO A2 list). Prevention of their introduction and epidemic outbreaks requires a reliable and accurate identification. Currently, identification of these bacteria is time consuming and often problematic, mainly because of cross-reactions with other plant-associated bacteria in immunological tests and false-negative results in PCR detection methods. Furthermore, distinguishing closely related subspecies is not straightforward. This study aimed at evaluating the use of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) and a fragment of the gyrB sequence for the reliable and fast identification of the Clavibacter subspecies. Amplification and sequencing of gyrB using a single primer set had sufficient resolution and specificity to identify each subspecies based on both sequence similarities in cluster analyses and specific signatures within the sequences. All five subspecies also generated distinct and reproducible MALDI-TOF MS profiles, with unique and specific ion peaks for each subspecies, which could be used as biomarkers for identification. Results from both methods were in agreement and were able to distinguish the five Clavibacter subspecies from each other and from representatives of closely related Rathayibacter, Leifsonia or Curtobacterium species. Our study suggests that proteomic analysis using MALDI-TOF MS and gyrB sequence are powerful diagnostic tools for the accurate identification of Clavibacter plant pathogens. PMID:21802235

Zaluga, Joanna; Heylen, Kim; Van Hoorde, Koenraad; Hoste, Bart; Van Vaerenbergh, Johan; Maes, Martine; De Vos, Paul

2011-09-01

118

SELDI-TOF MS profiling of serum for detection of the progression of chronic hepatitis C to hepatocellular carcinoma.  

PubMed

Proteomic profiling of serum is an emerging technique to identify new biomarkers indicative of disease severity and progression. The objective of our study was to assess the use of surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF MS) to identify multiple serum protein biomarkers for detection of liver disease progression to hepatocellular carcinoma (HCC). A cohort of 170 serum samples obtained from subjects in the United States with no liver disease (n = 39), liver diseases not associated with cirrhosis (n = 36), cirrhosis (n = 38), or HCC (n = 57) were applied to metal affinity protein chips for protein profiling by SELDI-TOF MS. Across the four test groups, 38 differentially expressed proteins were used to generate multiple decision classification trees to distinguish the known disease states. Analysis of a subset of samples with only hepatitis C virus (HCV)-related disease was emphasized. The serum protein profiles of control patients were readily distinguished from each HCV-associated disease state. Two-way comparisons of chronic hepatitis C, HCV cirrhosis, or HCV-HCC versus healthy had a sensitivity/specificity range of 74% to 95%. For distinguishing chronic HCV from HCV-HCC, a sensitivity of 61% and a specificity of 76% were obtained. However, when the values of known serum markers alpha fetoprotein, des-gamma carboxyprothrombin, and GP73 were combined with the SELDI peak values, the sensitivity and specifity improved to 75% and 92%, respectively. In conclusion, SELDI-TOF MS serum profiling is able to distinguish HCC from liver disease before cirrhosis as well as cirrhosis, especially in patients with HCV infection compared with other etiologies. PMID:15726646

Schwegler, E Ellen; Cazares, Lisa; Steel, Laura F; Adam, Bao-Ling; Johnson, David A; Semmes, O John; Block, Timothy M; Marrero, Jorge A; Drake, Richard R

2005-03-01

119

Multiplexed Ion Mobility Spectrometry - Orthogonal Time-Of-Flight Mass Spectrometry  

SciTech Connect

Ion mobility spectrometry (IMS) coupled to orthogonal time-of-flight mass spectrometry (TOF) has shown significant promise for the characterization of complex biological mixtures. The enormous complexity of biological samples (e.g. from proteomics) and the need for both biological and technical analysis replicates imposes major challenges for multidimensional separation platforms in regard to both sensitivity and sample throughput. A major potential attraction of the IMS-TOF MS platform is separation speeds exceeding that of conventional condensed-phase separations by orders of magnitude. Known limitations of the IMS-TOF MS platforms that presently mitigate this attraction include the need for extensive signal averaging due to factors that include significant ion losses in the IMS-TOF interface and an ion utilization efficiency of less than ~1% with continuous ion sources (e.g. ESI). We have developed a new multiplexed ESI-IMS-TOF mass spectrometer that enables lossless ion transmission through the IMS-TOF as well as a utilization efficiency of >50% for ions from the ESI source. Initial results with a mixture of peptides show a ~10-fold increase in signal-to-noise ratio with the multiplexed approach compared to a signal averaging approach, with no reduction in either IMS or TOF MS resolution.

Belov, Mikhail E.; Buschbach, Michael A.; Prior, David C.; Tang, Keqi; Smith, Richard D.

2007-03-15

120

Wavelet-based adaptive denoising and baseline correction for MALDI TOF MS.  

PubMed

Proteomic profiling by MALDI TOF mass spectrometry (MS) is an effective method for identifying biomarkers from human serum/plasma, but the process is complicated by the presence of noise in the spectra. In MALDI TOF MS, the major noise source is chemical noise, which is defined as the interference from matrix material and its clusters. Because chemical noise is nonstationary and nonwhite, wavelet-based denoising is more effective than conventional noise reduction schemes based on Fourier analysis. However, current wavelet-based denoising methods for mass spectrometry do not fully consider the characteristics of chemical noise. In this article, we propose new wavelet-based high-frequency noise reduction and baseline correction methods that were designed based on the discrete stationary wavelet transform. The high-frequency noise reduction algorithm adaptively estimates the time-varying threshold for each frequency subband from multiple realizations of chemical noise and removes noise from mass spectra of samples using the estimated thresholds. The baseline correction algorithm computes the monotonically decreasing baseline in the highest approximation of the wavelet domain. The experimental results demonstrate that our algorithms effectively remove artifacts in mass spectra that are due to chemical noise while preserving informative features as compared to commonly used denoising methods. PMID:20455751

Shin, Hyunjin; Sampat, Mehul P; Koomen, John M; Markey, Mia K

2010-06-01

121

Rapid determination of the geographical origin of honey based on protein fingerprinting and barcoding using MALDI TOF MS.  

PubMed

The authentication of foods is an important aspect of quality control and food safety. Honey is one of the most natural and most popular foods in the world. A fast and reliable method to determine the geographical origin of honey was developed based on fingerprinting and barcoding of proteins in honey by using matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI TOF MS) and MALDI Biotyper 1.1 software, respectively. The protein mass spectra of 16 honey samples of known Hawaii origin were obtained and peak information was extracted to generate protein fingerprints. This information was transformed into a database library of spectral barcodes that were used for differentiation of the geographical origin of honeys based on pattern matching. The differentiation ability of the database library of barcodes was validated by comparing the results of replicate assays of 5 of the 16 honey samples of known Hawaii origin obtained directly from the producers. Validation results showed that the protein fingerprints of honeys have better comparability with those honeys in the library known to be from the same region than with those of honey samples from other regions. The protein fingerprints were used to differentiate the geographical origins of commercially purchased honey samples with labels indicating that they were produced in different countries and various states of the USA, including Hawaii. The results showed that the MALDI TOF MS Biotyper system can be a rapid, simple and practical method for determining the geographical origin of honeys sold in commerce. PMID:19886676

Wang, Jun; Kliks, Michael M; Qu, Weiyue; Jun, Soojin; Shi, Gongyi; Li, Qing X

2009-11-11

122

High Throughput Detection of Tetracycline Residues in Milk Using Graphene or Graphene Oxide as MALDI-TOF MS Matrix  

NASA Astrophysics Data System (ADS)

In this work, a new pre-analysis method for tetracyclines (TCs) detection from the milk samples was established. As a good accomplishment for the existing accurate quantification strategies for TCs detection, the new pre-analysis method was demonstrated to be simple, sensitive, fast, cost effective, and high throughput, which would do a great favor to the routine quality pre-analysis of TCs from milk samples. Graphene or graphene oxide was utilized, for the first time, as a duel-platform to enrich and detect the TCs by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). All together, four TCs were chosen as models: tetracycline, oxytetracycline, demeclocycline, and chlortetracycline. Due to the excellent electronic, thermal, and mechanical properties, graphene and graphene oxide were successfully applied as matrices for MALDI-TOF MS with free background inference in low mass range. Meanwhile, graphene or graphene oxide has a large surface area and strong interaction force with the analytes. By taking the advantage of these features, TCs were effectively enriched with the limit of detection (LOD) as low as 2 nM.

Liu, Junyan; Liu, Yang; Gao, Mingxia; Zhang, Xiangmin

2012-08-01

123

Leptospira spp. strain identification by MALDI TOF MS is an equivalent tool to 16S rRNA gene sequencing and multi locus sequence typing (MLST)  

PubMed Central

Background In this study mass spectrometry was used for evaluating extracted leptospiral protein samples and results were compared with molecular typing methods. For this, an extraction protocol for Leptospira spp. was independently established in two separate laboratories. Reference spectra were created with 28 leptospiral strains, including pathogenic, non-pathogenic and intermediate strains. This set of spectra was then evaluated on the basis of measurements with well-defined, cultured leptospiral strains and with 16 field isolates of veterinary or human origin. To verify discriminating peaks for the applied pathogenic strains, statistical analysis of the protein spectra was performed using the software tool ClinProTools. In addition, a dendrogram of the reference spectra was compared with phylogenetic trees of the 16S rRNA gene sequences and multi locus sequence typing (MLST) analysis. Results Defined and reproducible protein spectra using MALDI-TOF MS were obtained for all leptospiral strains. Evaluation of the newly-built reference spectra database allowed reproducible identification at the species level for the defined leptospiral strains and the field isolates. Statistical analysis of three pathogenic genomospecies revealed peak differences at the species level and for certain serovars analyzed in this study. Specific peak patterns were reproducibly detected for the serovars Tarassovi, Saxkoebing, Pomona, Copenhageni, Australis, Icterohaemorrhagiae and Grippotyphosa. Analysis of the dendrograms of the MLST data, the 16S rRNA sequencing, and the MALDI-TOF MS reference spectra showed comparable clustering. Conclusions MALDI-TOF MS analysis is a fast and reliable method for species identification, although Leptospira organisms need to be produced in a time-consuming culture process. All leptospiral strains were identified, at least at the species level, using our described extraction protocol. Statistical analysis of the three genomospecies L. borgpetersenii, L. interrogans and L. kirschneri revealed distinctive, reproducible differentiating peaks for seven leptospiral strains which represent seven serovars. Results obtained by MALDI-TOF MS were confirmed by MLST and 16S rRNA gene sequencing.

2012-01-01

124

Multilocus sequence typing of Streptococcus pneumoniae by use of mass spectrometry.  

PubMed

Multilocus sequence typing (MLST) is an important tool for the global surveillance of bacterial pathogens that is performed by comparing the sequences of designated housekeeping genes. We developed and tested a novel mass spectrometry-based method for MLST of Streptococcus pneumoniae. PCR amplicons were subjected to in vitro transcription and base-specific cleavage, followed by analysis of the resultant fragments by using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). Comparison of the cleavage fragment peak patterns to a reference sequence set permitted automated identification of alleles. Validation experiments using 29 isolates of S. pneumoniae revealed that the results of MALDI-TOF MS MLST matched those obtained by traditional sequence-based MLST for 99% of alleles and that the MALDI-TOF MS method accurately identified two single-nucleotide variations. The MADLI-TOF MS method was then used for MLST analysis of 43 S. pneumoniae isolates from Papua New Guinean children. The majority of the isolates present in this population were not clonal and contained seven new alleles and 30 previously unreported sequence types. PMID:21880964

Dunne, Eileen M; Ong, Eng Kok; Moser, Ralf J; Siba, Peter M; Phuanukoonnon, Suparat; Greenhill, Andrew R; Robins-Browne, Roy M; Mulholland, E Kim; Satzke, Catherine

2011-11-01

125

Powerful GC-TOF-MS Techniques for Screening, Identification and Quantification of Halogenated Natural Products  

PubMed Central

Comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry (GC×GC TOFMS) and gas chromatography/high-resolution time-of-flight mass spectrometry (GC-HRT) were used to detect and identify halogenated natural products (HNPs) in tissue homogenate, in this case brominated analytes present in a marine snail. Two classes of brominated anthropogenic compounds, polybrominated diphenyl ethers (PBDEs) and brominated dibenzofurans, were analyzed for comparison. Following conventional preparation, the sample was analyzed using GC×GC-TOF-MS. Isotope ratio scripts were used to compile a list of putatively brominated analytes from amongst the thousands of features resolved in the two-dimensional chromatogram. The structured nature of the chromatogram was exploited to propose identifications for several classes of brominated compounds, and include additional candidates that fell marginally outside the script tolerances. The sample was subsequently analyzed by GC-HRT. The high-resolution mass spectral data confirmed many formula assignments, facilitated confident assignment of an alternate formula when an original proposal did not hold, and enabled unknown identification. Identified HNPs include hydroxylated and methoxylated PBDE analogs, polybrominated dibenzo-p-dioxins (PBDDs) and hydroxyl-PBDDs, permitting the environmental occurrence and fate of such compounds to be studied.

S. Haglund, Peter; Lofstrand, Karin; Siek, Kevin; Asplund, Lillemor

2013-01-01

126

Improved analysis of melamine-formaldehyde resins by capillary zone electrophoresis-mass spectrometry using ion-trap and quadrupole-time-of-flight mass spectrometers.  

PubMed

An improved method based on capillary zone electrophoresis (CZE) coupled to either ion-trap (IT) mass spectrometry (MS) or quadrupole-time-of-flight (Q-TOF) MS for the analysis of melamine-formaldehyde condensates is presented. Employing a formic acid-based electrolyte containing 50% acetonitrile (ACN) and MS detection up to 13 compounds could be determined in lab-made resins, synthesized by mixing formaldehyde and melamine in different ratios ranging from 1:1.5 to 1:4. The use of a Q-TOF-MS for detection allowed the assignment of molecular formulas for all 13 substances with high accuracy. PMID:18621379

Vo, Thuy Diep Thanh; Himmelsbach, Markus; Haunschmidt, Manuela; Buchberger, Wolfgang; Schwarzinger, Clemens; Klampfl, Christian W

2008-12-01

127

Identification and Cluster Analysis of Streptococcus pyogenes by MALDI-TOF Mass Spectrometry  

PubMed Central

Background Whole-cell matrix–assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) has been successfully applied for bacterial identification and typing of many pathogens. The fast and reliable qualities of MALDI-TOF MS make it suitable for clinical diagnostics. MALDI-TOF MS for the identification and cluster analysis of Streptococcus pyogenes, however, has not been reported. The goal of our study was to evaluate this approach for the rapid identification and typing of S. pyogenes. Methods 65 S. pyogenes isolates were obtained from the hospital. The samples were prepared and MALDI-TOF MS measurements were conducted as previously reported. Identification of unknown spectra was performed via a pattern recognition algorithm with a reference spectra and a dendrogram was constructed using the statistical toolbox in Matlab 7.1 integrated in the MALDI Biotyper 2.0 software. Results For identification, 61 of 65 S. pyogenes isolates could be identified correctly by MALDI-TOF MS with BioType 2.0 when compared to biochemical identification (API Strep), with an accuracy of 93.85%. In clustering analysis, 44 of 65 isolates were in accordance with those established by M typing, with a matching rate of 67.69%. When only the M type prevalence in China was considered, 41 of 45 isolates were in agreement with M typing, with a matching rate of 91.1%. Conclusions It was here shown that MALDI-TOF MS with Soft Biotype 2.0 and its database could facilitate rapid identification of S. pyogenes. It may present an attractive alternative to traditional biochemical methods of identification. However, for classification, more isolates and advances in the MALDI-TOF MS technology are needed to improve accuracy.

Hao, Huaijie; Kang, Lin; Zheng, Yuling; Jiang, Yongqiang; Jiang, Hua

2012-01-01

128

Peptidomic analysis of Chinese shrimp ( Fenneropenaeus chinensis) hemolymph by magnetic bead-based MALDI-TOF MS  

NASA Astrophysics Data System (ADS)

Peptides in shrimp hemolymph play an important role in the innate immune response. Analysis of hemolymph will help to detect and identify potential novel biomarkers of microbial infection. We used magnetic bead-based purification (ClinProt system) and matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) to characterize shrimp hemolymph peptides. Shrimp serum and plasma were used as the source of samples for comparative analysis, and it was found that serum was more suitable for shrimp hemolymph peptidomic analysis. To screen potential specific biomarkers in serum of immune-challenged shrimps, we applied magnetic bead-based MALDI-TOF MS to serum samples from 10 immune-challenged and 10 healthy shrimps. The spectra were analyzed using FlexAnalysis 3.0 and ClinProTools 2.1 software. Thirteen peptide peaks significantly different between the two groups were selected as candidate biomarkers of lipopolysaccharide (LPS)-infection. The diagnostic model established by genetic algorithm using five of these peaks was able to discriminate LPS-challenged shrimps from healthy control shrimps with a sensitivity of 90% and a specificity of 100%. Our approach in MALDITOF MS-based peptidomics is a powerful tool for screening bioactive peptides or biomarkers derived from hemolymph, and will help to enable a better understanding of the innate immune response of shrimps.

Wang, Baojie; Liu, Mei; Jiang, Keyong; Zhang, Guofan; Wang, Lei

2013-03-01

129

Analysis of raw hams using SELDI-TOF-MS to predict the final quality of dry-cured hams.  

PubMed

The relationship between protein profiles of Gluteus medius (GM) muscles of raw hams obtained from 4 pure breed pigs (Duroc, Large White, Landrace, and Piétrain) with the final quality of the Semimembranosus and Biceps femoris muscles of dry-cured hams was investigated. As expected, Duroc hams showed higher levels of marbling and intramuscular fat content than the other breeds. Piétrain hams were the leanest and most conformed, and presented the lowest salt content in dry-cured hams. Even if differences in the quality traits (colour, water activity, texture, composition, intramuscular fat, and marbling) of dry-cured hams were observed among the studied breeds, only small differences in the sensory attributes were detected. Surface-enhanced laser desorption/ionisation time-of-flight mass spectrometry (SELDI-TOF-MS) was used to obtain the soluble protein profiles of GM muscles. Some associations between protein peaks obtained with SELDI-TOF-MS and quality traits, mainly colour (b*) and texture (F(0), Y(2), Y(90)) were observed. Candidate protein markers for the quality of processed dry-cured hams were identified. PMID:23036942

Marcos, B; Gou, P; Serra, X; Guàrdia, M D; Zhen, Z Y; Hortós, M; Mach, N; te Pas, M F W; Keuning, E; Kruijt, L; Font i Furnols, M; Arnau, J

2013-02-01

130

Precise identification of photosynthetic glycerolipids in microalga Tetraselmis chuii by UPLC-ESI-Q-TOF-MS.  

PubMed

Precise structural identification of photosynthetic polar glycerolipids in microalga Tetraselmis chuii has been established using Ultra Performance Liquid Chromatography-Electrospray ionization-Quadrupole-Time of Flight Mass Spectrometry (UPLC-ESI-Q-TOF-MS) by direct analysis of the total lipids extract. The mass spectrometry was performed in reflective time-of-flight using electron spraying ionization in both positive and negative modes. The structural determination was based on the characteristic product ions yielded by different glycerolipids under ESI-MS/MS mode, and confirmed the molecular species by the carboxylate anions produced by glycerolipids in the negative mode. As a result, more than 40 lipid molecular species, including 11 monogalactosyldiacylglycerols (MGDG), 7 digalactosyldiacylglycerols (DGDG), 16 sulfoquinovosyldiacylglycerols (SQDG), and 9 phosphatidylglycerols (PG), were detected in Tetraselmis chuii, which had never been identified before in this microalga. Furthermore, some intact lipid molecules with hydroxylated fatty acids that could not be detected by the traditional GC-MS method were found this time, providing novel information for the photosynthetic lipidome of Tetraselmis chuii. Comparative studies on fatty acids at the sn-2 position showed that SQDG and MGDG are dominantly biosynthesized through the prokaryotic pathway, PG is a typically mixed biosynthetic pathway, while DGDG is somewhat peculiar with C14:0 and C16:0 at its sn-2 position. This method could provide a full structural profile of intact photosynthetic lipid molecular species, which may be applied to study the physiological and ecological functions of lipid by monitoring their individual changes. PMID:19093084

Li, HaiYing; Yan, XiaoJun; Xu, JiLin; Zhou, ChengXu

2008-12-01

131

Analysis of metal-binding proteins separated by non-denaturating gel electrophoresis using matrix-assisted laser desorption\\/ionization mass spectrometry (MALDI-MS) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS)  

Microsoft Academic Search

Matrix-assisted laser desorption\\/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) have become established as very efficient and sensitive biopolymer and elemental mass spectrometric techniques for studying metal-binding proteins (metalloproteins) in life sciences. Protein complexes present in rat tissues (liver and kidney) were separated in their native state in the first dimension by blue native

J. Susanne Becker; Sandra Mounicou; Miroslav V. Zoriy; J. Sabine Becker; Ryszard Lobinski

2008-01-01

132

Fragmentation study of five trichothecenes using electrospray hybrid ion trap\\/time-of-flight mass spectrometry with accurate mass measurements  

Microsoft Academic Search

Five trichothecenes, T-2 toxin, HT-2 toxin, deoxynivalenol (DON), 3-acetyl-DON (3-AcDON) and nivalenol (NIV), major class of mycotoxins produced by Fusarium, were investigated by electrospray hybrid ion trap\\/time-of-flight mass spectrometry (IT–TOF-MS). Fragmentation mechanisms are proposed based on the MS2 and MS3 experiments and accurate mass measurements. The sodium adduct ions [M+Na]+ of type-A trichothecenes, such as T-2 toxin and HT-2 toxin,

Zhao-Ying Liu; Chun-Hong Yu; Leren Wan; Zhi-Liang Sun

133

Determination of Diethylpyrocarbonate-Modified Amino Acid Residues in ? 1Acid Glycoprotein by High-Performance Liquid Chromatography Electrospray Ionization–Mass Spectrometry and Matrix-Assisted Laser Desorption\\/Ionization Time-of-Flight–Mass Spectrometry  

Microsoft Academic Search

The chemical modification reagent diethylpyrocarbonate (DEPC) was used to modify ?1-acid glycoprotein (orosomucoid, OMD) under various conditions. The extents of DEPC modification of the histidine and tyrosine residues were followed by UV spectrophotometry. The resulting modified OMD was analyzed using enzyme digestion, reverse-phase HPLC, electrospray ionization–mass spectrometry (ESI\\/MS), and matrix-assisted laser desorption ionization time-of-flight–mass spectrometry (MALDI-TOF\\/MS). The inherent problem of

Jeffrey L. Dage; Haijun Sun; H. Brian Halsall

1998-01-01

134

Comparison of software tools to improve the detection of carcinogen induced changes in the rat liver proteome by analyzing SELDI-TOF-MS spectra.  

PubMed

A common animal model of chemical hepatocarcinogenesis was used to demonstrate the potential identification of carcinogenicity related protein signatures/biomarkers. Therefore, an animal study in which rats were treated with the known liver carcinogen N-nitrosomorpholine (NNM) or the corresponding vehicle was evaluated. Histopathological investigation as well as SELDI-TOF-MS analysis was performed. SELDI-TOF-MS is an affinity-based mass spectrometry method in which subsets of proteins from biological samples are selectively adsorbed to a chemically modified surface. The proteins are subsequently analyzed with respect to their mass-charge ratios (m/z) by a time of flight (TOF) mass spectrometry (MS) approach. As data preprocessing of SELDI-TOF-MS spectra is essential, baseline correction, normalization, peak detection, and alignment of raw spectra were performed using either the Ciphergen ProteinChip Software 3.1 or functions implemented in the library PROcess of the BioConductor Project. Baseline correction and normalization algorithms of both tools lead to comparable results, whereas results after peak detection and alignment steps differed. Variability between technical and biological replicates was investigated. A linear mixed model with factors experimental group and time point was applied for each protein peak, taking into account the different correlation structure of technical and biological replicates. Alternatively, only median intensity values of technical replicates were used. Results of both models were similar and correlated well with those of the histopathological evaluation of the study. In conclusion, statistical analyses lead to comparable results, whereas parameter settings for preprocessing proved to be crucial. PMID:16457590

Beyer, Suse; Walter, Yvonne; Hellmann, Juergen; Kramer, Peter-Juergen; Kopp-Schneider, Annette; Kroeger, Michaela; Ittrich, Carina

2006-02-01

135

Application status of MALDI-TOF mass spectrometry in the identification and drug resistance of Mycobacterium tuberculosis  

PubMed Central

Characterizing Mycobacterium tuberculosis (MTB) and detecting its drug resistance are challenging for clinical laboratory diagnosis, largely due to its slow growth and higher rate of genetic mutation. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) is a revolutionary technique for the routine identification of microorganisms. In this review, we discuss the application status of mass spectrometry in the identification and drug resistance of M. tuberculosis.

Zhang, Ruixue; Long, Yin; He, Wenfang; Hao, Xiaoke

2014-01-01

136

Identification of unknown pesticides in fruits using ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry. Imazalil as a case study of quantification.  

PubMed

Ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QqTOF-MS) is an emerging technique offering more rapid and efficient separation, as well as the possibility to obtain accurate mass measurement and tandem mass spectrometry (MS/MS). This paper deals with the use of UPLC-QqTOF-MS to identify the pesticide residues present in complex pear extracts. Carbendazim, imazalil, and ethoxyquin were successfully identified because of the accurate mass determination of their protonated molecule and their major fragments in the product ion mass spectra. A few plastic and latex additives were also found, most of them probably coming from the packaging transfer to the fruits. The potential of the UPLC-QqTOF-MS and UPLC-QqTOF-MS/MS techniques as a quantification tool is also discussed taking imazalil as example. For quantification, calibration curves were linear over a dynamic range of 2 orders of magnitude, whereas higher calibration ranges are better adjusted to polynomial curves of second and third order. Quantification using different mass windows was also assessed. Accurate quantification required mass windows as wide as 20 mDa, narrower mass windows of 5 mDa provided erroneous quantification, probably because the low ion abundance. The mean recoveries and percentage relative standard deviation (RSD) of 35 determinations for imazalil were 76% (13% RSD) by MS and 77% (14% RSD) by MS/MS. The theoretical limit of detection was 0.4 microg kg(-1), with a validated limit of quantification of 2 microg kg(-1). The quantitative data obtained using UPLC-QqTOF-MS were compared with those obtained using conventional liquid chromatography (LC)-MS/MS with a triple quadrupole (QqQ). It was concluded that UPLC-QqTOF-MS might become a powerful analytical tool for both, unknown's identification and quantification of target pesticides. PMID:18021786

Picó, Yolanda; la Farré, Marinel; Soler, Carla; Barceló, Damià

2007-12-28

137

Sensitive high-resolution analysis of biological molecules by capillary zone electrophoresis coupled with reflecting time-of-flight mass spectrometry  

Microsoft Academic Search

Off-line and on-line capillary zone electrophoresis–electrospray ionization time-of-flight mass spectrometry (CZE–ESI-TOF-MS) experiments were conducted using uncoated fused-silica capillaries coupled to a reflecting TOF mass spectrometer via a gold-coated sheathless interface. Off-line and on-line experiments were performed on standard mixtures of proteins and peptides. Samples collected off-line electrokinetically in plastic vials were analyzed by standard ESI–TOF-MS at the pmol level. Sheathless

Mark E. McComb; Andrew N. Krutchinsky; Werner Ens; Kenneth G. Standing; Hélène Perreault

1998-01-01

138

Oxidation reactions of hydroxy naphthoquinones: Mechanistic investigation by LC-Q-TOF-MS analysis.  

PubMed

Abstract Purpose: The hydroxyl radical ((?)OH)-induced oxidation reactions of isomeric hydroxy naphthoquinones (generally having anti-tumor activities) namely, lawsone and juglone, were carried out and the reaction mechanism was elucidated. Materials and methods: The degradation products from the reaction of (?)OH (produced by H2O2/UV) with lawsone and juglone were analyzed using a liquid chromatography quadrupole-time-of-flight mass spectrometer (LC-Q-TOF-MS). The transient intermediate studies were investigated using picosecond pulse radiolysis technique. Results: Mono hydroxylated and dihydroxylated adducts of both lawsone and juglone were identified from the product analysis. The isomeric mono-hydroxylated adducts of lawsone were confirmed using survival yield (SY) analysis. The hydroxylated adducts of lawsone also underwent dimerization reaction. The transient spectral analysis using pulse radiolysis studies revealed the formation of hydroxycyclohexadienyl type radical of both lawsone and juglone as the initially formed intermediate. Conclusions: The (?)OH-induced reactions of both lawsone and juglone result in the mono and di-hydoxylated derivatives. The demonstration of the various isomeric products using mass spectrometry is a clear proof of the addition probability of (?)OH at different positions of lawsone and juglone, which is generally a difficult task using other analytical techniques. PMID:24597783

Sreekanth, Radhakrishnan; Menachery, Sunil Paul M; Aravind, Usha K; Marignier, Jean-Louis; Belloni, Jacqueline; Aravindakumar, Charuvila T

2014-06-01

139

[Study on intervention effect of Jieduquyuziyin prescription systemic lupus erythematosus by HPLC-Q-TOF/MS].  

PubMed

To establish a metabonomic method based on high performance liquid chromatography-quadrupole-time of flight mass spectrometry (HPLC-Q-TOF/MS), in order to study the changes in serum metabolites of systemic lupus erythematosus (SLE) mice after treatment of Jieduquyuziyin prescription, the pathogenesis of SLE and mechanism of drug action. The orthogonal partial least squares (OPLS) was applied for the pattern recognition of experimental data, finding a significant difference in the control group, the SLE model group, the Jieduquyuziyin prescription-treated group and the prednisone acetate-treated group. According to the OPLS load diagram, 12 differential metabolites, including traumatic acid, PAF, 12 (S)-HEPE, 15(S)-HETrE and Hepoxilin B3 were identified by using accurate mass combined with MS/MS data After treatment with Jieduquyuziyin prescription, the relative contents of PAF, 12 (S)-HETE were close to the level of the control group. According to the analysis on metabolic pathway, SLE could cause significant changes in unsaturated fatty acid and amino acid metabolism pathway, while Jieduquyuziyin prescription has a effect in regulating disorder of unsaturated fatty acid metabolism pathway. PMID:24494566

Hu, Jin-Bo; Gu, Heng-Cun; Ding, Zhi-Shan; Yao, Li; Fan, Yong-Sheng; Ding, Xing-Hong

2013-11-01

140

UPLC-Q-TOF-MS analysis of non-volatile migrants from new active packaging materials.  

PubMed

Ultra-performance liquid chromatography (UPLC) coupled to mass spectrometry (MS) is a useful tool in the analysis of non-volatile compounds, and the use of a quadrupole-time-of-flight (Q-TOF) mass analyzer allows a high sensitivity and accuracy when acquiring full fragment mode, providing a high assurance of correct identification of unknown compounds. In this work, UPLC-Q-TOF-MS technology has been applied to the analysis of non-volatile migrants from new active packaging materials. The materials tested were based on polypropylene (PP), ethylene-vinyl alcohol copolymer (EVOH), and poly(ethylene terephthalate) (PET). The active packaging materials studied were one PP film containing a natural antioxidant, and two PP/EVOH films, two PET/EVOH films and one coextruded PP/EVOH/PP film containing natural antimicrobials. The chemical structure of several compounds was unequivocally identified. The analysis revealed the migration of some of the active substances used in the manufacture of active packaging, such as caffeine (0.07 ± 0.01 ?g/g), carvacrol (0.31 ± 0.03 ?g/g) and citral (0.20 ± 0.01 ?g/g). Unintentionally added substances were also found, such as citral reaction compounds, or citral impurities present in the raw materials. PMID:22836481

Aznar, M; Rodriguez-Lafuente, A; Alfaro, P; Nerin, C

2012-10-01

141

Quantification of proteins on gold nanoparticles by combining MALDI-TOF MS and proteolysis  

NASA Astrophysics Data System (ADS)

Protein-coated nanoparticles have been used in many studies, including those related to drug delivery, disease diagnosis, therapeutics, and bioassays. The number and density of proteins on the particles’ surface are important parameters that need to be calculable in most applications. While quantification methods for two-dimensional surface-bound proteins are commonly found, only a few methods for the quantification of proteins on three-dimensional surfaces such as nanoparticles have been reported. In this paper, we report on a new method of quantifying proteins on nanoparticles using matrix assisted laser desorption/ionization time of flight (MALDI-TOF) mass spectrometry (MS). In this method, the nanoparticle-bound proteins are digested by trypsin and the resulting peptide fragments are analyzed by MALDI-TOF MS after the addition of an isotope-labeled internal standard (IS) which has the same sequence as a reference peptide of the surface-bound protein. Comparing the mass intensities between the reference peptide and the IS allows the absolute quantification of proteins on nanoparticles, because they have the same molecular milieu. As a model system, gold nanoparticles were examined using bovine serum albumin (BSA) as a coating protein. We believe that our strategy will be a useful tool that can provide researchers with quantitative information about the proteins on surfaces of three-dimensional materials.

Ju, Soomi; Yeo, Woon-Seok

2012-04-01

142

Chemical profiling of Wu-tou decoction by UPLC-Q-TOF-MS.  

PubMed

Wu-tou decoction (WTD), a traditional Chinese medicine (TCM) formula, is composed of Aconiti Radix Cocta, Ephedrae Herba, Paeoniae Radix Alba, Astragali Radix and Glycyrrhiza Radix Preparata, and it has been used for more than a thousand years to treat rheumatic arthritis, rheumatoid arthritis and pain of joints, while the active constitutions of WTD are unclear. In this research, an ultra performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) method in both positive and negative ion mode was established to investigate the major constitutions in WTD. A Waters ACQUITY UPLC BEH C18 column was used to separate the aqueous extract of WTD. Acetonitrile and 0.1% aqueous formic acid (v/v) were used as the mobile phase. 74 components including alkaloids, monoterpene glycosides, triterpene saponins, flavones and flavone glycosides were identified or tentatively characterized in WTD based on the accurate mass within 15 ppm error and tandem MS behavior. All the constitutions were also detected in the corresponding individual herbs. These results will provide a basis for further study in vivo of WTD and the information of potential new drug structure for treating rheumatic arthritis and rheumatoid arthritis. PMID:24274266

Qi, Yao; Li, Shizhe; Pi, Zifeng; Song, Fengrui; Lin, Na; Liu, Shu; Liu, Zhiqiang

2014-01-15

143

Novel, Improved Sample Preparation for Rapid, Direct Identification from Positive Blood Cultures Using Matrix-Assisted Laser Desorption/Ionization Time-of-Flight (MALDI-TOF) Mass Spectrometry  

PubMed Central

Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) is widely used for rapid and reliable identification of bacteria and yeast grown on agar plates. Moreover, MALDI-TOF MS also holds promise for bacterial identification from blood culture (BC) broths in hospital laboratories. The most important technical step for the identification of bacteria from positive BCs by MALDI-TOF MS is sample preparation to remove blood cells and host proteins. We present a method for novel, rapid sample preparation using differential lysis of blood cells. We demonstrate the efficacy and ease of use of this sample preparation and subsequent MALDI-TOF MS identification, applying it to a total of 500 aerobic and anaerobic BCs reported to be positive by a Bactec 9240 system. In 86.5% of all BCs, the microorganism species were correctly identified. Moreover, in 18/27 mixed cultures at least one isolate was correctly identified. A novel method that adjusts the score value for MALDI-TOF MS results is proposed, further improving the proportion of correctly identified samples. The results of the present study show that the MALDI-TOF MS-based method allows rapid (<20 minutes) bacterial identification directly from positive BCs and with high accuracy.

Schubert, Soren; Weinert, Kirsten; Wagner, Chris; Gunzl, Beatrix; Wieser, Andreas; Maier, Thomas; Kostrzewa, Markus

2011-01-01

144

Identification of astilbin metabolites produced by human intestinal bacteria using UPLC-Q-TOF/MS.  

PubMed

Astilbin, mainly isolated from a commonly used herbal medicine, Smilax glabra Roxb (SGR), exhibits a variety of pharmacological activities and biological effects. It is metabolized by intestinal bacteria after oral administration which leads to the variation of ethnopharmacological profile of this traditional medicine. However, little is known on the interactions of this active compound with intestinal bacteria, which would be very helpful in unravelling how SGR works. In this study, different pure bacteria from human feces were isolated and were used to investigate their conversion capability of astilbin. Ultra-performance liquid chromatography/quadrupole-time-of-flight mass spectrometry (UPLC-Q-TOF/MS) technique combined with Metabolynx(TM) software was used to analyze astilbin and its metabolites. The parent compound and two metabolites (quercetin and eriodictyol) were detected in the isolated bacterial samples compared with blank samples. Quercetin was present in Enterococcus sp. 8B, 8-2 and 9-2 samples. Eriodictyol was only identified in Enterococcus sp. 8B sample. The metabolic routes and metabolites of astilbin produced by the different intestinal bacteria are reported for the first time. This will be useful for the investigation of the pharmacokinetic study of astilbin in vivo and the role of different intestinal bacteria in the metabolism of natural compounds. Copyright © 2014 John Wiley & Sons, Ltd. PMID:24399635

Zhao, Min; Xu, Jun; Qian, Dawei; Guo, Jianming; Jiang, Shu; Shang, Er-Xin; Duan, Jin-Ao

2014-07-01

145

LC-TOF/MS determination of phthalates in edible salts from food markets in Korea.  

PubMed

Residual quantities of 12 phthalates have been monitored in edible salts (raw salts, refined salts, refined salts with additives and baked salts) available in Korean food markets. Liquid-liquid extraction followed by liquid chromatography time-of-flight mass spectrometry (LC-TOF/MS) was used to analyse the samples. The method was validated and showed linear correlation (R (2) > 0.996) in the range 0.5-100 ng g(-1) for all target analytes. Recoveries were 85.9-108.4%, except for diethyl phthalate (DEP). Relative standard deviations (RSDs) were 2.7-6.0% and the limits of detection (LODs) were 1.2-2.8 ng g(-1). Although the contamination of phthalates in salt would be trivial in comparison to those of other main foods and below the reference dose of the Chronic Oral Exposure recommended by US-EPA, the availability of reference data could be valuable for food chemists and salt manufacturers. PMID:24779906

Dirwono, Warnadi; Nam, Yun Sik; Park, Hyun-Mee; Lee, Kang-Bong

2013-01-01

146

Optimization of MALDI-TOF MS for strain level differentiation of Arthrobacter isolates.  

PubMed

Matrix-assisted laser-desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been shown to be a rapid and sensitive method for characterization of bacteria, but it has not yet become a routine microbiological procedure. Currently there are no standardized protocols that would allow development of large libraries of reproducible protein profiles from a broad range of microorganisms to use for identification purposes. Important variables that may affect spectrum quality are MALDI matrices, solvents, cell growth condition, and culture age. In the present study our aim was to: (1) to determine optimal sample preparation and MALDI conditions for discrimination at the strain level; (2) to determine if changes in growth cycle correlated with MALDI spectrum changes; and (3) to compare level of isolate discrimination based on their MALDI spectra versus their 16S rRNA gene sequence. Using 16 strains of the Gram positive bacterium Arthrobacter, optimal spectra were obtained using two-layer sample application of intact cells grown on solid surface overlaid with a matrix consisting of sinapinic acid (SA) or alpha-cyano-hydroxy-cinnaminic acid (CHCA) in 50:50 acetonitrile:water solvent with 2% trifluoroacetic acid. Spectrum changes paralleled the coccus-rod-coccus growth cycle indicative of Arthrobacter. Strain differences based on their MALDI profiles (using Pearson coefficient and UPGMA) corresponded with their 16S rRNA gene phylogeny but it had greater discrimination. PMID:16513195

Vargha, Márta; Takáts, Zoltán; Konopka, Allan; Nakatsu, Cindy H

2006-09-01

147

A method for improving SELDI-TOF mass spectrometry data quality  

Microsoft Academic Search

BACKGROUND: Surface-enhanced laser desorption\\/ionization time-of-flight mass spectrometry (SELDI-TOF MS) is a powerful tool for rapidly generating high-throughput protein profiles from a large number of samples. However, the events that occur between the first and last sample run are likely to introduce technical variation in the results. METHODS: We fractionated and analyzed quality control and investigational serum samples on 3 Protein

Toni Whistler; Dominique Rollin; Suzanne D Vernon

2007-01-01

148

Comparison of PCR/Electron spray Ionization-Time-of-Flight-Mass Spectrometry versus Traditional Clinical Microbiology for active surveillance of organisms contaminating high-use surfaces in a burn intensive care unit, an orthopedic ward and healthcare workers  

PubMed Central

Background Understanding nosocomial pathogen transmission is restricted by culture limitations. Novel platforms, such as PCR-based electron spray ionization-time-of-flight-mass spectrometry (ESI-TOF-MS), may be useful as investigational tools. Methods Traditional clinical microbiology (TCM) and PCR/ESI-TOF-MS were used to recover and detect microorganisms from the hands and personal protective equipment of 10 burn intensive care unit (ICU) healthcare workers providing clinical care at a tertiary care military referral hospital. High-use environmental surfaces were assessed in 9 burn ICU and 10 orthopedic patient rooms. Clinical cultures during the study period were reviewed for pathogen comparison with investigational molecular diagnostic methods. Results From 158 samples, 142 organisms were identified by TCM and 718 by PCR/ESI-TOF-MS. The molecular diagnostic method detected more organisms (4.5?±?2.1 vs. 0.9?±?0.8, p?TOF-MS. Gram-negative organisms were less commonly identified than gram-positive by both methods; especially by TCM. Among all detected bacterial species, similar percentages were typical nosocomial pathogens (18-19%) for TCM vs. PCR/ESI-TOF-MS. PCR/ESI-TOF-MS also detected mecA in 112 samples, vanA in 13, and KPC-3 in 2. MecA was associated (p?TOF-MS detected more organisms, especially gram-negatives, compared to TCM, but the current assay format is limited by the number of antibiotic resistance determinants it covers. Further large-scale assessments of PCR/ESI-TOF-MS for hospital surveillance are warranted.

2012-01-01

149

Direct Identification of Urinary Tract Pathogens from Urine Samples by Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry?  

PubMed Central

Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) has been suggested as a reliable method for bacterial identification from cultures. Direct analysis of clinical samples might increase the usefulness of this method, shortening the time for microorganism identification. We compared conventional methods for the diagnosis of urinary tract infections (UTIs) and identification of the urinary tract pathogens (automated screening, plate cultures, and identification based on biochemical characteristics) and a fast method based on conventional screening and MALDI-TOF MS. For this latter method, 4 ml of urine was centrifuged at a low-revolution setting (2,000 × g) to remove leukocytes and then at high revolutions (15,500 × g) to collect bacteria. The pellet was washed and then applied directly to the MALDI-TOF MS plate. Two hundred sixty urine samples, detected as positive by the screening device (UF-1000i), were processed by culture and MALDI-TOF MS. Twenty samples were positive in the screening device but negative in culture, and all of them were also negative by MALDI-TOF MS. Two-hundred thirty-five samples displayed significant growth of a single morphological type in culture. Two-hundred twenty of them showed bacterial growth of >105 CFU/ml. Microorganism identifications in this group were coincident at the species level in 202 cases (91.8%) and at the genus level in 204 cases (92.7%). The most frequent microorganism was Escherichia coli (173 isolates). MALDI-TOF MS identified this microorganism directly from the urine sample in 163 cases (94.2%). Our results show that MALDI-TOF MS allows bacterial identification directly from infected urine in a short time, with high accuracy, and especially when Gram-negative bacteria with high bacterial counts are involved.

Ferreira, Laura; Sanchez-Juanes, Fernando; Gonzalez-Avila, Magdalena; Cembrero-Fucinos, David; Herrero-Hernandez, Ana; Gonzalez-Buitrago, Jose Manuel; Munoz-Bellido, Juan Luis

2010-01-01

150

Identification of Rare Pathogenic Bacteria in a Clinical Microbiology Laboratory: Impact of Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry  

PubMed Central

During the past 5 years, matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) mass spectrometry (MS) has become a powerful tool for routine identification in many clinical laboratories. We analyzed our 11-year experience in routine identification of clinical isolates (40 months using MALDI-TOF MS and 91 months using conventional phenotypic identification [CPI]). Among the 286,842 clonal isolates, 284,899 isolates of 459 species were identified. The remaining 1,951 isolates were misidentified and required confirmation using a second phenotypic identification for 670 isolates and using a molecular technique for 1,273 isolates of 339 species. MALDI-TOF MS annually identified 112 species, i.e., 36 species/10,000 isolates, compared to 44 species, i.e., 19 species/10,000 isolates, for CPI. Only 50 isolates required second phenotypic identifications during the MALDI-TOF MS period (i.e., 4.5 reidentifications/10,000 isolates) compared with 620 isolates during the CPI period (i.e., 35.2/10,000 isolates). We identified 128 bacterial species rarely reported as human pathogens, including 48 using phenotypic techniques (22 using CPI and 37 using MALDI-TOF MS). Another 75 rare species were identified using molecular methods. MALDI-TOF MS reduced the time required for identification by 55-fold and 169-fold and the cost by 5-fold and 96-fold compared with CPI and gene sequencing, respectively. MALDI-TOF MS was a powerful tool not only for routine bacterial identification but also for identification of rare bacterial species implicated in human infectious diseases. The ability to rapidly identify bacterial species rarely described as pathogens in specific clinical specimens will help us to study the clinical burden resulting from the emergence of these species as human pathogens, and MALDI-TOF MS may be considered an alternative to molecular methods in clinical laboratories.

Seng, Piseth; Abat, Cedric; Rolain, Jean Marc; Colson, Philippe; Lagier, Jean-Christophe; Gouriet, Frederique; Fournier, Pierre Edouard; Drancourt, Michel; La Scola, Bernard

2013-01-01

151

Characterization of Microorganisms by MALDI Mass Spectrometry  

SciTech Connect

Matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS) for characterization and analysis of microorganisms, specifically bacteria, is described here as a rapid screening tool. The objective of this technique is not comprehensive protein analysis of a microorganism but rather a rapid screening of the organism and the accessible protein pattern for characterization and distinction. This method is based on the ionization of the readily accessible and easily ionizable portion of the protein profile of an organism that is often characteristic of different bacterial species. The utility of this screening approach is yet to reach its full potential but could be applied to food safety, disease outbreak monitoring in hospitals, culture stock integrity and verification, microbial forensics or homeland security applications.

Petersen, Catherine E.; Valentine, Nancy B.; Wahl, Karen L.

2008-10-02

152

Identification of Gallibacterium species by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry evaluated by multilocus sequence analysis.  

PubMed

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) whole-cell fingerprinting was used for characterization of 66 reference strains of Gallibacterium. The 4 recognised Gallibacterium species and Gallibacterium genomospecies 1 yielded reproducible and unique mass spectrum profiles, which were confirmed with Bruker Biotyper reference database version 3. The reproducibility of MALDI-TOF MS results were evaluated varying the age and storage of the cultures investigated. Reliable species identification was possible for up to 8 days of storage at 4°C and less reliable if the bacteria were stored at room temperature (20°C). However, if the strains were grown longer than 48h at 37°C under microaerobic atmosphere, poor identification results were obtained, due to changes in protein profile. The MALDI-TOF MS results of all 66 strains demonstrated 87.9% concordance with results based upon biochemical/physiological characterization. In addition, diversities outlined by MALDI-TOF MS were verified by sequencing the rpoB (n=43), 16S rRNA (n=28), infB (n=14), and recN (n=14) genes (multilocus sequence analysis, MLSA). In addition, discrepancies were observed between some of the genes sequenced. Results obtained demonstrated that MALDI-TOF MS fingerprinting represents a fast and reliable method for identification and differentiation of the 4 recognised Gallibacterium species and possible a fifth species Gallibacterium genomospecies 1, with applications in clinical diagnostics. PMID:21596619

Alispahic, Merima; Christensen, Henrik; Hess, Claudia; Razzazi-Fazeli, Ebrahim; Bisgaard, Magne; Hess, Michael

2011-08-01

153

Issues of Processing and Multiple Testing of SELDI-TOF MS Proteomic Data  

Microsoft Academic Search

A new data filtering method for SELDI-TOF MS proteomic spectra data is described. We examined technical repeats (2 per subject) of intensity versus m\\/z (mass\\/charge) of bone marrow cell lysate for two groups of childhood leukemia patients: acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL). As others have noted, the type of data processing as well as experimental variability

Merrill D. Birkner; Alan E. Hubbard; Mark J. van der Laan; Christine F. Skibola; Christine M. Hegedus; Martyn T. Smith

2006-01-01

154

Analysis of fresh Mentha haplocalyx volatile components by comprehensive two-dimensional gas chromatography and high-resolution time-of-flight mass spectrometry.  

PubMed

Fresh Mentha haplocalyx is a well known traditional Chinese medicinal material (CMM) used in both China and America. This paper reports analysis of the volatile components of fresh Mentha haplocalyx by comprehensive two-dimensional gas chromatography (GCxGC) and high-resolution time-of-flight mass spectrometry (HR-TOF-MS), a combination that provides almost complete chemical separation with elemental composition determination of analytes. 163 ketones and terpenes, including menthol and menthone, were tentatively identified, including enantiomers. This study suggests that GCxGCxHR-TOF-MS is suitable for routine identification of target compounds and enantiomers in CMM. PMID:21915401

Cao, Gang; Shan, Qiyuan; Li, Xiaomeng; Cong, Xiaodong; Zhang, Yun; Cai, Hao; Cai, Baochang

2011-11-21

155

Differentiation of Raoultella ornithinolytica/planticola and Klebsiella oxytoca clinical isolates by matrix-assisted laser desorption/ionization-time of flight mass spectrometry.  

PubMed

Ninety-nine clinical isolates previously identified as Klebsiella oxytoca were evaluated using matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS). Eight isolates were identified as Raoultella spp., being 5 Raoultella spp. and 3 K. oxytoca, by 16S rRNA sequencing. These isolates were correctly identified by applying the 10% differential rule for the MALDI-TOF MS score values. This approach might be useful to discriminate Raoultella species from K. oxytoca. PMID:23375086

de Jong, Eefje; de Jong, Arjan S; Smidts-van den Berg, Nathalie; Rentenaar, Rob J

2013-04-01

156

Utility of Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry following Introduction for Routine Laboratory Bacterial Identification ?  

PubMed Central

Matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) was evaluated prospectively in a diagnostic laboratory. Nine hundred twenty-seven organisms were tested in triplicate; 2,351/2,781 (85%) species and 2,681/2,781 (96%) genus identifications were correct. Known issues such as the misidentification of alpha-hemolytic streptococci as Streptococcus pneumoniae were easily corrected. Identifications cost AUD$0.45 per isolate and were available in minutes. MALDI-TOF MS is rapid, accurate, and inexpensive.

Neville, Stephen A.; LeCordier, Annabelle; Ziochos, Helen; Chater, Mathew J.; Gosbell, Iain B.; Maley, Michael W.; van Hal, Sebastiaan J.

2011-01-01

157

Potential Pitfalls in MALDI-TOF MS Analysis of Abiotically Synthesized RNA Oligonucleotides  

NASA Astrophysics Data System (ADS)

Demonstration of the abiotic polymerization of ribonucleotides under conditions consistent with conditions that may have existed on the prebiotic Earth is an important goal in "RNA world" research. Recent reports of abiotic RNA polymerization with and without catalysis rely on techniques such as HPLC, gel electrophoresis, and MALDI-TOF MS to analyze the reaction products. It is essential to understand the limitations of these techniques in order to accurately interpret the results of these analyses. In particular, techniques that rely on mass for peak identification may not be able to distinguish between a single, linear RNA oligomer and stable aggregates of smaller linear and/or cyclic RNA molecules. In the case of MALDI-TOF MS, additional complications may arise from formation of salt adducts and MALDI matrix complexes. This is especially true for abiotic RNA polymerization reactions because the concentration of longer RNA chains can be quite low and RNA, as a polyelectrolyte, is highly susceptible to adduct formation and aggregation. Here we focus on MALDI-TOF MS analysis of abiotic polymerization products of imidazole-activated AMP in the presence and absence of montmorillonite clay as a catalyst. A low molecular weight oligonucleotide standard designed for use in MALDI-TOF MS and a 3'-5' polyadenosine monophosphate reference standard were also run for comparison and calibration. Clay-catalyzed reaction products of activated GMP and UMP were also examined. The results illustrate the ambiguities associated with assignment of m/z values in MALDI mass spectra and the need for accurate calibration of mass spectra and careful sample preparation to minimize the formation of adducts and other complications arising from the MALDI process.

Burcar, Bradley T.; Cassidy, Lauren M.; Moriarty, Elizabeth M.; Joshi, Prakash C.; Coari, Kristin M.; McGown, Linda B.

2013-06-01

158

Analysis of alkenone unsaturation indices with fast gas chromatography/time-of-flight mass spectrometry.  

PubMed

Extensively purified C37 alkenone references and mixtures thereof were analyzed by gas chromatography/flame ionization detection (GC/FID) and fast gas chromatography/time-of-flight mass spectrometry (GC/TOF-MS), to establish the latter as an alternative, fast, and reliable analysis method for alkenone unsaturation indices (U(k')(37)). This index is a tool for past sea surface temperature reconstructions with extensive use in paleoclimate and paleoceanographic research. TOF-MS was chosen because of its unique capability to acquire full-range spectra at high data rates (up to 500 spectra s(-1)) and to produce homogeneous spectra across a gaschromatographic peak, allowing faster separations than conventional GC/MS and the employment of enhanced peak deconvolution algorithms. Analysis time per sample could be reduced to run times of <10 min, i.e., by a factor of approximately 10 compared to conventional GC/FID (90-100 min) methods. However, %@mt;sys@%%@ital@%%@bold@%U%@reset@%%@rsf@%%@sx@%37%@be@%%@ital@%k%@rsf@%'%@sxx@%%@mx@% values from GC/TOF-MS showed deviations from those obtained by GC/FID, resulting from sensitivity differences between the C37:2 and C37:3 alkenone when analyzed by GC/TOF-MS. A solution to this bias is presented by determining compound-specific linear response factor equations to derive sensitivity ratios (SR) that allow conversion of GC/TOF-MS values into calibrated GC/FID data. Using alkenone mixtures of known composition and a variety of samples from natural environments, the applicability of this approach is demonstrated. PMID:18288817

Hefter, J

2008-03-15

159

Evaluation of matrix-assisted laser desorption ionization-time of flight mass spectrometry for identification of clinically important yeast species.  

PubMed

We evaluated the use of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) for the rapid identification of yeast species. Using Bruker Daltonics MALDI BioTyper software, we created a spectral database library with m/z ratios of 2,000 to 20,000 Da for 109 type and reference strains of yeast (44 species in 8 genera). The database was tested for accuracy by use of 194 clinical isolates (23 species in 6 genera). A total of 192 (99.0%) of the clinical isolates were identified accurately by MALDI-TOF MS. The MALDI-TOF MS-based method was found to be reproducible and accurate, with low consumable costs and minimal preparation time. PMID:20668126

Stevenson, Lindsay G; Drake, Steven K; Shea, Yvonne R; Zelazny, Adrian M; Murray, Patrick R

2010-10-01

160

Evaluation of Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry for Identification of Clinically Important Yeast Species ?  

PubMed Central

We evaluated the use of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) for the rapid identification of yeast species. Using Bruker Daltonics MALDI BioTyper software, we created a spectral database library with m/z ratios of 2,000 to 20,000 Da for 109 type and reference strains of yeast (44 species in 8 genera). The database was tested for accuracy by use of 194 clinical isolates (23 species in 6 genera). A total of 192 (99.0%) of the clinical isolates were identified accurately by MALDI-TOF MS. The MALDI-TOF MS-based method was found to be reproducible and accurate, with low consumable costs and minimal preparation time.

Stevenson, Lindsay G.; Drake, Steven K.; Shea, Yvonne R.; Zelazny, Adrian M.; Murray, Patrick R.

2010-01-01

161

Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry: a Fundamental Shift in the Routine Practice of Clinical Microbiology  

PubMed Central

SUMMARY Within the past decade, clinical microbiology laboratories experienced revolutionary changes in the way in which microorganisms are identified, moving away from slow, traditional microbial identification algorithms toward rapid molecular methods and mass spectrometry (MS). Historically, MS was clinically utilized as a high-complexity method adapted for protein-centered analysis of samples in chemistry and hematology laboratories. Today, matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) MS is adapted for use in microbiology laboratories, where it serves as a paradigm-shifting, rapid, and robust method for accurate microbial identification. Multiple instrument platforms, marketed by well-established manufacturers, are beginning to displace automated phenotypic identification instruments and in some cases genetic sequence-based identification practices. This review summarizes the current position of MALDI-TOF MS in clinical research and in diagnostic clinical microbiology laboratories and serves as a primer to examine the “nuts and bolts” of MALDI-TOF MS, highlighting research associated with sample preparation, spectral analysis, and accuracy. Currently available MALDI-TOF MS hardware and software platforms that support the use of MALDI-TOF with direct and precultured specimens and integration of the technology into the laboratory workflow are also discussed. Finally, this review closes with a prospective view of the future of MALDI-TOF MS in the clinical microbiology laboratory to accelerate diagnosis and microbial identification to improve patient care.

Clark, Andrew E.; Kaleta, Erin J.; Arora, Amit

2013-01-01

162

Ion Mobility SpectrometryMass Spectrometry Performance Using Electrodynamic Ion Funnels and Elevated Drift Gas Pressures  

SciTech Connect

The ability of ion mobility spectrometry coupled with mass spectrometry (IMS-MS) to characterize biological mixtures has been illustrated over the past eight years. However, the challenges posed by the extreme complexity of many biological samples have demonstrated the need for higher resolution IMS-MS measurements. We have developed a higher resolution ESI-IMS-TOF MS by utilizing high pressure electrodynamic ion funnels at both ends of the IMS drift cell and operating the drift cell at an elevated pressure compared to a previous design. The ESI-IMS-TOF MS instrument consists of an ESI source, an hourglass ion funnel used for ion accumulation/injection into an 88 cm drift cell followed by a 10 cm ion funnel and a commercial orthogonal time-of-flight mass spectrometer providing high mass measurement accuracy. It was found that the rear (exit) ion funnel could be effectively operated as an extension of the drift cell when the DC fields were matched, allowing the instrument to have an effective drift region of 98 cm. Two differentially pumped quadrupole regions were used to couple the IMS and TOF MS to focus and minimize the ion transient time between the stages. The resolution of the instrument was evaluated at pressures ranging from 4 to12 Torr and ion mobility drift voltages of 16 V/cm (4 Torr) to 43 V/cm (12 Torr). An increase in resolution from 55 to 80 was observed from 4 to 12 Torr nitrogen drift gas with no loss in sensitivity. Given the increased usage of ion funnels prior to ion mobility separations, additional attention was directed towards the influence of drift gas on the observed ion populations trapped and transmitted using an electrodynamic ion funnel. The choice of drift gas was shown to influence the degree of ion heating and relative trapping efficiency within the ion funnel.

Baker, Erin Shammel; Clowers, Brian H.; Li, Fumin; Tang, Keqi; Tolmachev, Aleksey V.; Prior, David C.; Belov, Mikhail E.; Smith, Richard D.

2007-06-28

163

Interference free detection for small molecules: probing the Mn2+-doped effect and cysteine capped effect on the ZnS nanoparticles for coccidiostats and peptide analysis in SALDI-TOF MS.  

PubMed

For the first time, we report the applications of Mn(2+)-doped ZnS@cysteine nanoparticles (NPs) as matrices for analysis of coccidiostats (lasalocid, monensin, salinomycin and narasin) and peptide mixtures (Met-enk, Leu-enk, HW6 and gramicidin) in surface-assisted laser desorption/ionization time-of-flight mass spectrometry (SALDI-TOF MS). The Mn(2+)-doped ZnS@cysteine NPs have been successfully synthesized in aqueous phase and characterized by SEM, TEM and FT-IR spectroscopy. Comparison with the bare ZnS NPs, ZnS@cysteine NPs and CHCA to serve as matrices, we found that using Mn(2+)-doped ZnS@cysteine NPs as matrices offer better detection sensitivity and less background interferences for small molecule analysis. Current approach has been successfully applied for the analysis of peptide mixtures in urine samples and coccidiostats from egg samples by SALDI-TOF MS. The Mn(2+) ions doped in ZnS@cysteine NPs play a significant role for enhancing the detection sensitivity of analytes in SALDI-TOF MS. We believe that this approach is a promising tool to solve the low mass interference problems in MALDI-MS for complex mixture analysis of peptides and drugs. PMID:20419264

Kailasa, Suresh Kumar; Wu, Hui-Fen

2010-05-01

164

MALDI TOF MS: An Exobiology Surface-Science Approach for Europa  

NASA Astrophysics Data System (ADS)

If Europa is to be of primary exobiological interest, namely as a habitat for extant life, it is obvious that: i) a hydrosphere must prevail beneath the cryosphere for a long time; ii) internal energy sources must be present in a sufficient state of activity; and iii) a reasonable technical means must be available for assessing if indeed life does exist in the hypothesized hydrosphere. This discussion focuses on technical issues, because the compounding evidence about Europa indicates that the first two are highly likely to be true. We present a consideration of time-of-flight mass spectroscopy (TOF MS) conducted in-situ on the cryosphere surface of Europa during a landed robotic mission. We assert that this is a reasonable technical means not only for exploring the composition of the cryosphere itself, but also for locating any biomolecular indicators of extant life brought to the surface through cryosphere activity. We also describe a MALDI (Matrix Laser Desorption and Ionization) TOF MS system that we are constructing as a proof-of-concept prototype for conducting TOF MS measurements on Europa.

Gerakines, Perry A.; Wdowiak, Thomas J.

2002-11-01

165

MALDI-TOF Mass Spectrometry Detection of Pathogens in Vectors: The Borrelia crocidurae/Ornithodoros sonrai Paradigm  

PubMed Central

Background In Africa, relapsing fever borreliae are neglected vector-borne pathogens that cause mild to deadly septicemia and miscarriage. Screening vectors for the presence of borreliae currently requires technically demanding, time- and resource-consuming molecular methods. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) has recently emerged as a tool for the rapid identification of vectors and the identification of cultured borreliae. We investigated whether MALDI-TOF-MS could detect relapsing fever borreliae directly in ticks. Methodology/Principal Findings As a first step, a Borrelia MALDI-TOF-MS database was created to house the newly determined Mean Spectrum Projections for four Lyme disease group and ten relapsing fever group reference borreliae. MALDI-TOF-MS yielded a unique protein profile for each of the 14 tested Borrelia species, with 100% reproducibility over 12 repeats. In a second proof-of-concept step, the Borrelia database and a custom software program that subtracts the uninfected O. sonrai profile were used to detect Borrelia crocidurae in 20 Ornithodoros sonrai ticks, including eight ticks that tested positive for B. crocidurae by PCR-sequencing. A B. crocidurae-specific pattern consisting of 3405, 5071, 5898, 7041, 8580 and 9757-m/z peaks was found in all B. crocidurae-infected ticks and not found in any of the un-infected ticks. In a final blind validation step, MALDI-TOF-MS exhibited 88.9% sensitivity and 93.75% specificity for the detection of B. crocidurae in 50 O. sonrai ticks, including 18 that tested positive for B. crocidurae by PCR-sequencing. MALDI-TOF-MS took 45 minutes to be completed. Conclusions/Significance After the development of an appropriate database, MALDI-TOF-MS can be used to identify tick species and the presence of relapsing fever borreliae in a single assay. This work paves the way for the use of MALDI-TOF-MS for the dual identification of vectors and vectorized pathogens.

Fotso Fotso, Aurelien; Mediannikov, Oleg; Diatta, Georges; Almeras, Lionel; Flaudrops, Christophe; Parola, Philippe; Drancourt, Michel

2014-01-01

166

LC/TOF-MS Identification of Organic Components in Cloud and Fog Water Samples  

NASA Astrophysics Data System (ADS)

The nature and identity of organic compounds in cloud and fog droplets are not well understood. Approximately 80 percent of the total organic carbon remains unidentified due to several confounding factors. Traditionally, many of the organic compound analyses have been accomplished by the use of gas chromatography (GC) / mass spectrometry (MS) methods. These methods require analytes to be extracted from water and introduced into the GC by the use of organic solvents. Extraction efficiencies of the water- soluble organic components vary widely depending upon molecular size and polarity. Additionally, many polar compounds are thermally labile and require derivatization to make them more amenable for GC/MS analysis. Liquid chromatography (LC) methods which allow for sample introduction in water have also been used widely for organic analyses. However, commonly used detection methods such as conductivity, UV absorbance, and fluorescence limit the identification of organic components based on detection specific associated physical properties. Recently, electrospray ionization has allowed for MS detection to be paired with LC. There exist several types of MS each with their own specific advantages and disadvantages. In this study, we used LC with accurate mass time of flight (TOF) MS. The distinct advantage of accurate mass TOF is that it may be used to identify unknown organic compounds. Here we present results from our search for novel organic components (including organic nitrogen and organosulfates) in a variety of cloud and fog water samples from polluted and rural environments. These results are paired with established measurement methods for liquid water content, pH, and concentrations of total organic carbon (TOC), dissolved organic carbon (DOC), carbohydrates, formaldehyde, low molecular weight organic acids, carbonyls, and organic nitrogen.

Rinehart, L. R.; Shen, X.; Collett, J. L.

2006-12-01

167

Collagen-based proteinaceous binder-pigment interaction study under UV ageing conditions by MALDI-TOF-MS and principal component analysis.  

PubMed

This study focuses on acquiring information on the degradation process of proteinaceous binders due to ultra violet (UV) radiation and possible interactions owing to the presence of historical mineral pigments. With this aim, three different paint model samples were prepared according to medieval recipes, using rabbit glue as proteinaceus binders. One of these model samples contained only the binder, and the other two were prepared by mixing each of the pigments (cinnabar or azurite) with the binder (glue tempera model samples). The model samples were studied by applying Principal Component Analysis (PCA) to their mass spectra obtained with Matrix-Assisted Laser Desorption/Ionization-Time of Flight Mass Spectrometry (MALDI-TOF-MS). The complementary use of Fourier Transform Infrared Spectroscopy to study conformational changes of secondary structure of the proteinaceous binder is also proposed. Ageing effects on the model samples after up to 3000?h of UV irradiation were periodically analyzed by the proposed approach. PCA on MS data proved capable of identifying significant changes in the model samples, and the results suggested different aging behavior based on the pigment present. This research represents the first attempt to use this approach (PCA on MALDI-TOF-MS data) in the field of Cultural Heritage and demonstrates the potential benefits in the study of proteinaceous artistic materials for purposes of conservation and restoration. PMID:22431458

Romero-Pastor, Julia; Navas, Natalia; Kuckova, Stepanka; Rodríguez-Navarro, Alejandro; Cardell, Carolina

2012-03-01

168

Identification of a variety of Staphylococcus species by matrix-assisted laser desorption ionization-time of flight mass spectrometry.  

PubMed

Whole-cell fingerprinting by matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) in combination with a dedicated bioinformatic software tool (MALDI Biotyper 2.0) was used to identify 152 staphylococcal strains corresponding to 22 staphylococcal species. Spectra of the 152 isolates, previously identified at the species level using a sodA gene-based oligonucleotide array, were analyzed against the main spectra of 3,030 microorganisms. A total of 151 strains out of 152 (99.3%) were correctly identified at the species level; only one strain was identified at the genus level. The MALDI-TOF MS method revealed different clonal lineages of Staphylococcus epidermidis that were of either human or environmental origin, which suggests that the MALDI-TOF MS method could be useful in the profiling of staphylococcal strains. The topology of the dendrogram generated by the MALDI Biotyper 2.0 software from the spectra of 120 Staphylococcus reference strains (representing 36 species) was in general agreement with that inferred from the 16S rRNA gene-based analysis. Our findings indicate that the MALDI-TOF MS technology, associated with a broad-spectrum reference database, is an effective tool for the swift and reliable identification of Staphylococci. PMID:20032251

Dubois, Damien; Leyssene, David; Chacornac, Jean Paul; Kostrzewa, Markus; Schmit, Pierre Olivier; Talon, Régine; Bonnet, Richard; Delmas, Julien

2010-03-01

169

Identification of a Variety of Staphylococcus Species by Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry ?  

PubMed Central

Whole-cell fingerprinting by matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) in combination with a dedicated bioinformatic software tool (MALDI Biotyper 2.0) was used to identify 152 staphylococcal strains corresponding to 22 staphylococcal species. Spectra of the 152 isolates, previously identified at the species level using a sodA gene-based oligonucleotide array, were analyzed against the main spectra of 3,030 microorganisms. A total of 151 strains out of 152 (99.3%) were correctly identified at the species level; only one strain was identified at the genus level. The MALDI-TOF MS method revealed different clonal lineages of Staphylococcus epidermidis that were of either human or environmental origin, which suggests that the MALDI-TOF MS method could be useful in the profiling of staphylococcal strains. The topology of the dendrogram generated by the MALDI Biotyper 2.0 software from the spectra of 120 Staphylococcus reference strains (representing 36 species) was in general agreement with that inferred from the 16S rRNA gene-based analysis. Our findings indicate that the MALDI-TOF MS technology, associated with a broad-spectrum reference database, is an effective tool for the swift and reliable identification of Staphylococci.

Dubois, Damien; Leyssene, David; Chacornac, Jean Paul; Kostrzewa, Markus; Schmit, Pierre Olivier; Talon, Regine; Bonnet, Richard; Delmas, Julien

2010-01-01

170

Rapid identification of acetic acid bacteria using MALDI-TOF mass spectrometry fingerprinting.  

PubMed

Acetic acid bacteria (AAB) are widespread microorganisms characterized by their ability to transform alcohols and sugar-alcohols into their corresponding organic acids. The suitability of matrix-assisted laser desorption-time of flight mass spectrometry (MALDI-TOF MS) for the identification of cultured AAB involved in the industrial production of vinegar was evaluated on 64 reference strains from the genera Acetobacter, Gluconacetobacter and Gluconobacter. Analysis of MS spectra obtained from single colonies of these strains confirmed their basic classification based on comparative 16S rRNA gene sequence analysis. MALDI-TOF analyses of isolates from vinegar cross-checked by comparative sequence analysis of 16S rRNA gene fragments allowed AAB to be identified, and it was possible to differentiate them from mixed cultures and non-AAB. The results showed that MALDI-TOF MS analysis was a rapid and reliable method for the clustering and identification of AAB species. PMID:23182036

Andrés-Barrao, Cristina; Benagli, Cinzia; Chappuis, Malou; Ortega Pérez, Ruben; Tonolla, Mauro; Barja, François

2013-03-01

171

The Effect of Culture Conditions on Microorganism Identification by Matrix-Assisted Laser Desorption Ionization Mass Spectrometry  

SciTech Connect

Abstract Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been used to identify bacteria based upon protein signatures. This research shows that while some different proteins are produced by vegetative bacteria when they are cultured in different growth media, positive identification with MALDI-TOF MS is still possible with the protocol established at Pacific Northwest National Laboratory (PNNL)(11). A core set of small proteins remain constant under at least four different culture media conditions including minimal medium -M9, rich media - tryptic soy broth (TSB) or Luria-Bertani (LB) broth and blood agar plates such that analysis of the intact cells by matrix-assisted laser desorption/ionization mass spectrometry allows for consistent identification.

Valentine, Nancy B.; Wunschel, Sharon C.; Wunschel, David S.; Petersen, Catherine E.; Wahl, Karen L.

2005-01-01

172

Comparison of VITEK2, MALDI-TOF MS, and 16S rDNA sequencing for identification of Myroides odoratus and Myroides odoratimimus.  

PubMed

The genus Myroides comprises the 2 medically relevant species Myroides odoratus and Myroides odoratimimus that are rare opportunistic pathogens and cause infections in immunocompromised patients. A fast identification of Myroides is of importance because these bacterial strains show multiple resistance against antibiotics and therefore limit treatment options. They are associated, for instance, with urinary tract infections, sepsis, meningitis, pneumonia, and infectious cellulitis. Since more and more Myroides spp. are being described, additional potentially pathogenic bacteria may be identified in the future demanding the need for fast and reliable identification methods at species level. However, to date, only molecular approaches meet these demands. In this study, we, therefore, attempt to define an appropriate method other than DNA fingerprinting that will permit a comparable efficacy and, possibly, a more economical strain identification. For this purpose, we compared 2 widely used automated diagnostic systems (VITEK 2 [bioMérieux, Nürtingen, Germany] and Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS) [Bruker Daltonics, Bremen, Germany]) and correlated the results to 16S rDNA sequencing data. In total, we analyzed 22 strains collected in the course of routine diagnostics. In this study, we demonstrate that VITEK 2 reliably identifies the genus Myroides but cannot differentiate between M. odoratimimus and M. odoratus. In contrast to this, both MALDI-TOF MS and 16S rDNA sequencing efficiently distinguish between the 2 species. PMID:24666701

Schröttner, Percy; Rudolph, Wolfram W; Eing, Bodo R; Bertram, Sebastian; Gunzer, Florian

2014-06-01

173

[UPLC-TOF/MS based chemical profiling approach to evaluate toxicity-attenuated chemical composition in combination of ginseng and radix aconiti praeparata].  

PubMed

In the present study, an ultra performance liquid chromatography coupled with time-of-fight mass spectrometry (UPLC-TOF/MS) based chemical profiling approach was used to evaluate chemical constitution between co-decoction and mixed decoction of ginseng and Radix Aconiti Praeparata. Two different kinds of decoctions, namely co-decoction of ginseng and Radix Aconiti Praeparata: water extract of mixed two herbs, and mixed decoction of ginseng and Radix Aconiti Praeparata: mixed water extract of each individual herbs, were prepared. Batches of these two kinds of decoction samples were subjected to UPLC-TOF/MS analysis. The datasets of t(R) m/z pairs, ion intensities and sample codes were processed with supervised partial least squared discriminant analysis (OPLS-DA) to holistically compare the difference between these two decoction samples. Significant difference between the two decoction samples was showed in the results of positive ion mode. The contents of hypaconitine and deoxyaconitine decreased, while that of benzoylmesaconine, benzoylhypaconine and dehydrated benzoylmesaconine increased in the samples of co-decoction of ginseng and Radix Aconiti Praeparata. The content of diester-diterpenoid alkaloids decreased, while that of monoester-diterpenoid alkaloids increased, which is probably the basis of toxicity-attenuated action when combined ginseng with Radix Aconiti Praeparata. PMID:22375424

Ma, Zeng-Chun; Zhou, Si-Si; Liang, Qian-De; Huo, Chao; Wang, Yu-Guang; Tan, Hong-Ling; Xiao, Cheng-Rong; Gao, Yue

2011-12-01

174

The Use of Principal Component Analysis in MALDI-TOF MS: a Powerful Tool for Establishing a Mini-optimized Proteomic Profile  

PubMed Central

Background Recently, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) technology has been applied to the exploration of biomarkers for early cancer diagnosis, but more effort is required to identify a single sensitive and specific biomarker. For early diagnosis, a proteomic profile is the gold standard, but inconvenient for clinical use since the profile peaks are quantitative. It would therefore be helpful to find a minimized profile, comprising fewer peaks than the original using an existing algorithm and compare it with other traditional statistical methods. Methods In the present study, principal component analysis (PCA) in the ClinProt-Tools of MALDI-TOF MS was used to establish a mini-optimized proteomic profile from gastric cancer patients and healthy controls, and the result was compared with t-test and Flexanalysis software. Results Eight peaks were selected as the mini-optimized proteomic profile to help differentiate between gastric cancer patients and healthy controls. The peaks at m/z 4212 were regarded as the most important peak by the PCA algorithm. The peaks at m/z 1866 and 2863 were identified as deriving from complement component C3 and apolipoprotein A1, respectively. Conclusions PCA enabled us to identify a mini-optimized profile consisting of significantly differentiating peaks and offered the clue for further research.

Shao, Changli; Tian, Yaping; Dong, Zhennan; Gao, Jing; Gao, Yanhong; Jia, Xingwang; Guo, Guanghong; Wen, Xinyu; Jiang, Chaoguang; Zhang, Xueji

2011-01-01

175

Systematic identification and quantification of tetracyclic monoterpenoid oxindole alkaloids in Uncaria rhynchophylla and their fragmentations in Q-TOF-MS spectra.  

PubMed

Uncaria rhynchophylla (UR) is a species of Uncaria that is distributed mainly in China and Japan. In this study, the chemical constituents, including alkaloids, flavonoids, and quinic acids, in UR have been systematically identified and quantified by a developed method of high-performance liquid chromatography coupled with diode-array detection and quadrupole time-of-flight mass spectrometry (Q-TOF-MS). Tetracyclic monoterpenoid oxindole alkaloids (TMOAs) are characteristic compounds in this herb, and their fragmentations in Q-TOF-MS have been investigated. Diagnostic fragmentation ions (DFIs) were first delineated for isorhynchophylline-type (7S, C20-ethyl) and corynoxeine-type (7R, C20-vinyl) TMOAs, and these were used for identification of these alkaloids in UR. In this study, a total of 29 compounds, comprising 18 alkaloids, six flavonoids, and five quinic acids, were identified. Among them, there are four novel TMOAs, named as 22-O-?-glucopyranosyl isorhynchophyllic acid (10), 22-O-?-glucopyranosyl rhynchophyllic acid (11), 9-hydroxy isocorynoxeine (16), and 9-hydroxy corynoxeine (20), which have not been reported previously. Furthermore, eight marker compounds, namely chlorogenic acid (3), catechin (8), epicatechin (9), isocorynoxeine (24), rhynchophylline (25), isorhynchophylline (27), vincoside lactam (28), and corynoxeine (29), have been simultaneously quantified. The developed method has been validated and successfully applied to analyze three samples of UR from Jiangxi Province. The contents of the marker compounds have been detected and compared. PMID:23624509

Xie, Shuanglu; Shi, Yuanyuan; Wang, Yixiang; Wu, Chunyong; Liu, Wenyuan; Feng, Feng; Xie, Ning

2013-01-01

176

Novel Mass Spectrometry-Based Tool for Genotypic Identification of Mycobacteria  

PubMed Central

Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) after base-specific cleavage of PCR amplified and in vitro-transcribed 16S rRNA gene (rDNA) was used for the identification of mycobacteria. Full-length 16S rDNA reference sequences of 12 type strains of Mycobacterium spp. frequently isolated from clinical specimens were determined by PCR, cloning, and sequencing. For MALDI-TOF MS-based comparative sequence analysis, mycobacterial 16S rDNA signature sequences (?500 bp) of the 12 type strains and 24 clinical isolates were PCR amplified using RNA promoter-tagged forward primers. T7 RNA polymerase-mediated transcription of forward strands in the presence of 5-methyl ribo-CTP maximized mass differences of fragments generated by base-specific cleavage. In vitro transcripts were subsequently treated with RNase T1, resulting in G-specific cleavage. Sample analysis by MALDI-TOF MS showed a specific mass signal pattern for each of the 12 type strains, allowing unambiguous identification. All 24 clinical isolates were identified unequivocally by comparing their detected mass signal pattern to the reference sequence-derived in silico pattern of the type strains and to the in silico mass patterns of published 16S rDNA sequences. A 16S rDNA microheterogeneity of the Mycobacterium xenopi type strain (DSM 43995) was detected by MALDI-TOF MS and later confirmed by Sanger dideoxy sequencing. In conclusion, analysis of 16S rDNA amplicons by MS after base-specific cleavage of RNA transcripts allowed fast and reliable identification of the Mycobacterium tuberculosis complex and ubiquitous mycobacteria (mycobacteria other than tuberculosis). The technology delivers an open platform for high-throughput microbial identification on the basis of any specific genotypic marker region.

Lefmann, Michael; Honisch, Christiane; Bocker, Sebastian; Storm, Niels; von Wintzingerode, Friedrich; Schlotelburg, Cord; Moter, Annette; van den Boom, Dirk; Gobel, Ulf B.

2004-01-01

177

Characterization of Acacia mangium polyflavonoid tannins by MALDI-TOF mass spectrometry and CP-MAS 13C NMR  

Microsoft Academic Search

The MALDI-TOF mass spectrometry (MS) and solid state CP-MAS 13C Nuclear Magnetic Resonance (NMR) spectroscopic technique were introduced to characterize Acacia mangium tannin (condensed tannins). The MALDI-TOF MS illustrated a series of peaks corresponding to oligomers of condensed tannins of up to 11 flavonoid units (3200Da). A. mangium condensed tannins were found to consist predominantly of prorobinetinidin combined with profisetinidin

Yeoh Beng Hoong; Antonio Pizzi; Harald Pasch

2010-01-01

178

Identification of phenolic compounds from pollen extracts using capillary electrophoresis–electrospray time-of-flight mass spectrometry  

Microsoft Academic Search

In this work, a new, easy and rapid method of analyzing phenolic compounds in pollen extract, based on capillary electrophoresis\\u000a coupled with electrospray ionization time-of-flight-mass spectrometry (CE–ESI–TOF–MS), has been developed. A systematic investigation\\u000a of separation parameters has been performed with respect to resolution, sensitivity, analysis time and peak shape. The electrophoretic\\u000a parameters and electrospray conditions must be optimized to obtain

D. Arráez-Román; G. Zurek; C. Bäßmann; N. Almaraz-Abarca; R. Quirantes; A. Segura-Carretero; A. Fernández-Gutiérrez

2007-01-01

179

Characterisation of Stevia Rebaudiana by comprehensive two-dimensional liquid chromatography time-of-flight mass spectrometry  

Microsoft Academic Search

Comprehensive two-dimensional liquid chromatography (LC×LC) connected on-line to electrospray ionisation time-of-flight mass spectrometry (ESI-TOF-MS) was employed for analysis of aqueous extract of Stevia rebaudiana. Different combinations of strong cation-exchange (SCX), amino (NH2), and octadecyl siloxane (C18) stationary phases were tested in the separation of all nine known sweet Stevia glycosides. A combination of C18 as the first-dimension column and NH2

Jaroslav Pól; Barbora Hohnová; Tuulia Hyötyläinen

2007-01-01

180

Quantitative quality-assessment techniques to compare fractionation and depletion methods in SELDI-TOF mass spectrometry experiments  

Microsoft Academic Search

Motivation: Mass-spectrometry (MS), such as the surface-enhanced laser desorption and ionization time-of-flight (SELDI-TOF) MS, pro- vides a potentially promising proteomic technology for biomarker discovery. An important matter for such a technology to be used routinely is its reproducibility. It is of significant interest to develop quantitative measures to evaluate the quality and reliability of different experimental methods. Results: We compare

Jaroslaw Harezlak; Mike Wang; David Christiani; Xihong Lin

2007-01-01

181

Chip-based nLC-TOF-MS is a highly stable technology for large scale high-throughput analyses  

PubMed Central

Many studies focused on the discovery of novel biomarkers for the diagnosis and treatment of disease states are facilitated by mass spectrometry based technology. HPLC coupled to mass spectrometry is widely used; miniaturization of this technique using nano-LC-MS usually results in better sensitivity, but is associated with limited repeatability. The recent introduction of chip-based technology has significantly improved the stability of nano-LC-MS, but no substantial studies to verify this have been performed. To evaluate the temporal repeatability of chip-based nano-LC-MS analyses, N-glycans released from a serum sample were repeatedly analyzed using a nLC-PGC-chip-TOF-MS on three non-consecutive days. With an average inter-day CV of 4%, determined on log10 transformed integrals, the repeatability of the system is very high. Overall, chip-based nano-LC-MS appears a highly stable technology, which is suitable for profiling of large numbers of clinical samples for biomarker discovery.

Ruhaak, L. Renee; Taylor, Sandra L.; Miyamoto, Suzanne; Kelly, Karen; Leiserowitz, Gary S.; Gandara, David; Lebrilla, Carlito B.; Kim, Kyoungmi

2013-01-01

182

Proteomic approach based on MALDI-TOF MS to detect powdered milk in fresh cow's milk.  

PubMed

Milk and cheese are expensive foodstuffs, and their consumption is spread among the population because of their high nutritional value; for this reason they are often subjected to adulterations. Among the common illegal practices, the addition of powdered derivatives seems very difficult to detect because the adulterant materials have almost the same chemical composition of liquid milk. However, the high temperatures (180-200 °C) used for milk powder production could imply the occurrence of some protein modifications (e.g., glycation, lactosylation, oxidation, deamidation, dehydration). The modified proteins or peptides could then be used as markers for the presence of powdered milk. In this work, matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) was employed to analyze tryptic digests relevant to samples of raw liquid (without heat treatment), commercial liquid, and powdered cow's milk. Samples were subjected to two-dimensional gel electrophoresis (2-DE); differences among liquid and powder milk were detected at this stage and eventually confirmed by MALDI analysis of the in gel digested proteins. Some diagnostic peptides of powdered milk, attributed to modified whey proteins and/or caseins, were identified. Then, a faster procedure was optimized, consisting of the separation of caseins from milk whey and the subsequent in-solution digestion of the two fractions, with the advantage of obtaining almost the same information in a limited amount of time. Finally, analyses were carried out with the fast procedure on liquid milk samples adulterated with powdered milk at different percentages, and diagnostic peptides were detected down to 1% of adulteration level. PMID:22931122

Calvano, Cosima Damiana; Monopoli, Antonio; Loizzo, Pasqua; Faccia, Michele; Zambonin, Carlo

2013-02-27

183

It's a MALDI but it's a goodie: MALDI-TOF mass spectrometry for microbial identification.  

PubMed

The last few years have witnessed a revolution in the diagnostic microbiology laboratory with the emergence of matrix assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS) as an indispensible tool in microbial identification. In many laboratories this has superseded biochemical profiling. A mass spectrum is acquired from an unknown micro-organism and this proteomic fingerprint is then compared with a database of reference spectra to ascertain the likely genus and species identity. The reproducibility of this method is facilitated by the analysis of continually produced, highly abundant proteins (mainly ribosomal proteins) in the mass range 2000 to 20?000?Da. MALDI-TOF MS is reliable and rapid and has the ability to determine the identity of an isolate from culture in a matter of minutes rather than the hours or days required by more traditional methods. In addition to microbial identification of cultured isolates, work is underway to extend the utility of MALDI-TOF MS to include bacterial identification directly from clinical samples as well as providing timely information regarding antibiotic resistance and typing of different micro-organisms. PMID:24781219

Randell, Paul

2014-08-01

184

Establishing Drug Resistance in Microorganisms by Mass Spectrometry  

NASA Astrophysics Data System (ADS)

A rapid method to determine drug resistance in bacteria based on mass spectrometry is presented. In it, a mass spectrum of an intact microorganism grown in drug-containing stable isotope-labeled media is compared with a mass spectrum of the intact microorganism grown in non-labeled media without the drug present. Drug resistance is determined by predicting characteristic mass shifts of one or more microorganism biomarkers using bioinformatics algorithms. Observing such characteristic mass shifts indicates that the microorganism is viable even in the presence of the drug, thus incorporating the isotopic label into characteristic biomarker molecules. The performance of the method is illustrated on the example of intact E. coli, grown in control (unlabeled) and 13C-labeled media, and analyzed by MALDI TOF MS. Algorithms for data analysis are presented as well.

Demirev, Plamen A.; Hagan, Nathan S.; Antoine, Miquel D.; Lin, Jeffrey S.; Feldman, Andrew B.

2013-08-01

185

Identification and subtyping of clinically relevant human and ruminant mycoplasmas by use of matrix-assisted laser desorption ionization-time of flight mass spectrometry.  

PubMed

Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) recently emerged as a technology for the identification of bacteria. In this study, we aimed to evaluate its applicability to human and ruminant mycoplasmal identification, which can be demanding and time-consuming when using phenotypic or molecular methods. In addition, MALDI-TOF MS was tested as a subtyping tool for certain species. A total of 29 main spectra (MSP) from 10 human and 13 ruminant mycoplasma (sub)species were included in a mycoplasma MSP database to complete the Bruker MALDI Biotyper database. After broth culture and protein extraction, MALDI-TOF MS was applied for the identification of 119 human and 143 ruminant clinical isolates that were previously identified by antigenic or molecular methods and for subcultures of 73 ruminant clinical specimens that potentially contained several mycoplasma species. MALDI-TOF MS resulted in accurate (sub)species-level identification with a score of ?1.700 for 96% (251/262) of the isolates. The phylogenetically closest (sub)species were unequivocally distinguished. Although mixtures of the strains were reliably detected up to a certain cellular ratio, only the predominant species was identified from the cultures of polymicrobial clinical specimens. For typing purposes, MALDI-TOF MS proved to cluster Mycoplasma bovis and Mycoplasma agalactiae isolates by their year of isolation and genome profiles, respectively, and Mycoplasma pneumoniae isolates by their adhesin P1 type. In conclusion, MALDI-TOF MS is a rapid, reliable, and cost-effective method for the routine identification of high-density growing mycoplasmal species and shows promising prospects for its capacity for strain typing. PMID:23903545

Pereyre, S; Tardy, F; Renaudin, H; Cauvin, E; Del Prá Netto Machado, L; Tricot, A; Benoit, F; Treilles, M; Bébéar, C

2013-10-01

186

Identification and Subtyping of Clinically Relevant Human and Ruminant Mycoplasmas by Use of Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry  

PubMed Central

Matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) recently emerged as a technology for the identification of bacteria. In this study, we aimed to evaluate its applicability to human and ruminant mycoplasmal identification, which can be demanding and time-consuming when using phenotypic or molecular methods. In addition, MALDI-TOF MS was tested as a subtyping tool for certain species. A total of 29 main spectra (MSP) from 10 human and 13 ruminant mycoplasma (sub)species were included in a mycoplasma MSP database to complete the Bruker MALDI Biotyper database. After broth culture and protein extraction, MALDI-TOF MS was applied for the identification of 119 human and 143 ruminant clinical isolates that were previously identified by antigenic or molecular methods and for subcultures of 73 ruminant clinical specimens that potentially contained several mycoplasma species. MALDI-TOF MS resulted in accurate (sub)species-level identification with a score of ?1.700 for 96% (251/262) of the isolates. The phylogenetically closest (sub)species were unequivocally distinguished. Although mixtures of the strains were reliably detected up to a certain cellular ratio, only the predominant species was identified from the cultures of polymicrobial clinical specimens. For typing purposes, MALDI-TOF MS proved to cluster Mycoplasma bovis and Mycoplasma agalactiae isolates by their year of isolation and genome profiles, respectively, and Mycoplasma pneumoniae isolates by their adhesin P1 type. In conclusion, MALDI-TOF MS is a rapid, reliable, and cost-effective method for the routine identification of high-density growing mycoplasmal species and shows promising prospects for its capacity for strain typing.

Renaudin, H.; Cauvin, E.; Del Pra Netto Machado, L.; Tricot, A.; Benoit, F.; Treilles, M.; Bebear, C.

2013-01-01

187

[Analysis and identification of chemical constituents in Siwu decoction by UPLC-Q-TOF-MS(E)].  

PubMed

This research analyzed the chemical constituents of Siwu decoction by UPLC-Q-TOF-MS(E). Base on the data of mass and related-literatures, 43 peaks were profiled and 25 compounds, which contain 8 monoterpene glycosides from Paeonia lactiflora and 13 phthalides from Rhizoma chuanxiong and Radix angelica sinensis mainly, were identified in both positive and negative mode respectively. Meanwhile, chemical constituents of water extract and 60% ethanol extract of Siwu decoction were compared by the principal constituent analysis with MarkerLynx software, which provides the basis for the active ingredients of Siwu decoction. PMID:24494558

Wang, Zhen-Fang; Zhao, Yang; Pang, Xu; Yu, He-Shui; Kang, Li-Ping; Gao, Yue; Ma, Bai-Ping

2013-11-01

188

[Analysis of alkaloids in Zanthoxylum nitidum by HPLC-DAD/ESI-Q-TOF-MS].  

PubMed

The alkaloids in Zanthoxylum nitidum were identified by HPLC-DAD/ESI-Q-TOF-MS. Separation was performed on a Hanbon C18 column with acetonitrile (with 0.1% formic acid) and water(with 0.1% formic acid) as mobile phase. Based on the high-resolution mass information, MS/MS fragmentation behaviors and chemical components from literatures, 48 components were identified or tentatively characterized including 6 new compounds. This work could be useful for the quality control and further studies of the plant. PMID:23944035

Jia, Chang-Ping; Huang, Xue-Li; Li, Yun; Feng, Fang

2013-04-01

189

Characterization of Bacteria in Ballast Water Using MALDI-TOF Mass Spectrometry  

PubMed Central

To evaluate a rapid and cost-effective method for monitoring bacteria in ballast water, several marine bacterial isolates were characterized by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). Since International Maritime Organization (IMO) regulations are concerned with the unintended transportation of pathogenic bacteria through ballast water, emphasis was placed on detecting species of Vibrio, enterococci and coliforms. Seawater samples collected from the North Sea were incubated in steel ballast tanks and the presence of potentially harmful species of Pseudomonas was also investigated. At the genus-level, the identification of thirty six isolates using MALDI-TOF MS produced similar results to those obtained by 16S rRNA gene sequencing. No pathogenic species were detected either by 16S rRNA gene analysis or by MALDI-TOF MS except for the opportunistically pathogenic bacterium Pseudomonas aeruginosa. In addition, in house software that calculated the correlation coefficient values (CCV) of the mass spectral raw data and their variation was developed and used to allow the rapid and efficient identification of marine bacteria in ballast water for the first time.

Emami, Kaveh; Askari, Vahid; Ullrich, Matthias; Mohinudeen, Khwajah; Anil, Arga Chandrashekar; Khandeparker, Lidita; Burgess, J. Grant; Mesbahi, Ehsan

2012-01-01

190

Liquid chromatography quadrupole time-of-flight mass spectrometry characterization of metabolites guided by the METLIN database.  

PubMed

Untargeted metabolomics provides a comprehensive platform for identifying metabolites whose levels are altered between two or more populations. By using liquid chromatography quadrupole time-of-flight mass spectrometry (LC-Q-TOF-MS), hundreds to thousands of peaks with a unique m/z ratio and retention time are routinely detected from most biological samples in an untargeted profiling experiment. Each peak, termed a metabolomic feature, can be characterized on the basis of its accurate mass, retention time and tandem mass spectral fragmentation pattern. Here a seven-step protocol is suggested for such a characterization by using the METLIN metabolite database. The protocol starts from untargeted metabolomic LC-Q-TOF-MS data that have been analyzed with the bioinformatics program XCMS, and it describes a strategy for selecting interesting features as well as performing subsequent targeted tandem MS. The seven steps described will require 2-4 h to complete per feature, depending on the compound. PMID:23391889

Zhu, Zheng-Jiang; Schultz, Andrew W; Wang, Junhua; Johnson, Caroline H; Yannone, Steven M; Patti, Gary J; Siuzdak, Gary

2013-03-01

191

Derivatized mesoporous silica beads for MALDI-TOF MS profiling of human plasma and urine.  

PubMed

Matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS) is a promising tool for large-scale screening of body fluids for the early detection of human diseases. Proteins, peptides, and metabolites present in cells, tissues, or in body fluids constitute the molecular signatures of individuals. The design and generation of material-based platforms for capturing molecular signatures from body fluids has gained increasing interest in recent years. Highly selective materials are attractive candidates for a wide range of applications in biofluid proteomics. We have therefore developed a procedure based on mesoporous silica particles for the selective binding and enrichment of low molecular weight plasma/serum proteins by MALDI MS analysis ( Terracciano, R., Gaspari, M., Testa, F., Pasqua, L., Cuda G., Tagliaferri, P., Cheng, M. C., Nijdam, A. J., Petricoin, E. F., Liotta, L. A., Ferrari, M., and Venuta, S. ( 2006 ) Selective binding and enrichment for low-molecular weight biomarker molecules in human plasma after exposure to nanoporous silica particles . Proteomics 6, 3243-3250 ). Mesoporous silica beads (MSB) are able to harvest peptides from plasma and serum by means of nanosized porous channels with high surface area, while excluding large size proteins. Moreover, the absorption properties can be modified since the pore walls can be functionalized with different chemical species due to the high concentration of silanol groups at the surface. In this study, we performed derivatization of MSB with different functionalities, and we evaluated the derivatized materials for plasma and urine peptidomic profiling. Aminopropyl, N-(2-aminoethyl)-3-aminopropyl, and N,N,N' tris-carboxymethyl ethylene diamine, have been introduced onto the mesoporous silica surfaces in order to modulate selective peptide enrichment. We also explored various experimental conditions in order to optimize the performance of chemically modified MSB in the peptide profiling of human plasma and urine. These new derivatized mesoporous surfaces, in addition to the previous nonderivatized MSB, constitute an extended and reliable platform of five distinct chromatographic phases with defined surface functionality and porosity. Several plasma and urine peptides were extracted from derivatized MSB and then profiled by MALDI-TOF MS. The reproducibility of sample preparation by different functionalized beads was evaluated via three replicate analyses of plasma and urine samples. Lower coefficients of variation in the mass values and peak intensities resulted for plasma in comparison to those of urine samples; nevertheless, these where satisfactory for diagnostic purposes. For human urine, a linear correlation was found between spiked peptide concentrations and their peak areas (R(2) > 0.98) with a limit of detection in the low-nanogram per milliliter range, thus confirming the high sensitivity of the methodology, previously demonstrated for human plasma. Different panels of peptide repertoires have thus been collected from highly porous substrates chemically conjugated with different functional groups, and these may be used in biomarker discovery for disease diagnosis. PMID:19338374

Terracciano, Rosa; Pasqua, Luigi; Casadonte, Francesca; Frascà, Stella; Preianò, Mariaimmacolata; Falcone, Daniela; Savino, Rocco

2009-05-20

192

Matrix-assisted laser desorption ionization-time of flight mass spectrometry for rapid identification of tick vectors.  

PubMed

A method for rapid species identification of ticks may help clinicians predict the disease outcomes of patients with tick bites and may inform the decision as to whether to administer postexposure prophylactic antibiotic treatment. We aimed to establish a matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) spectrum database based on the analysis of the legs of six tick vectors: Amblyomma variegatum, Rhipicephalus sanguineus, Hyalomma marginatum rufipes, Ixodes ricinus, Dermacentor marginatus, and Dermacentor reticulatus. A blind test was performed on a trial set of ticks to identify specimens of each species. Subsequently, we used MALDI-TOF MS to identify ticks obtained from the wild or removed from patients. The latter tick samples were also identified by 12S ribosomal DNA (rDNA) sequencing and were tested for bacterial infections. Ticks obtained from the wild or removed from patients (R. sanguineus, I. ricinus, and D. marginatus) were accurately identified using MALDI-TOF MS, with the exception of those ticks for which no spectra were available in the database. Furthermore, one damaged specimen was correctly identified as I. ricinus, a vector of Lyme disease, using MALDI-TOF MS only. Six of the 14 ticks removed from patients were found to be infected by pathogens that included Rickettsia, Anaplasma, and Borrelia spp. MALDI-TOF MS appears to be an effective tool for the rapid identification of tick vectors that requires no previous expertise in tick identification. The benefits for clinicians include the more targeted surveillance of patients for symptoms of potentially transmitted diseases and the ability to make more informed decisions as to whether to administer postexposure prophylactic treatment. PMID:23224087

Yssouf, Amina; Flaudrops, Christophe; Drali, Rezak; Kernif, Tahar; Socolovschi, Cristina; Berenger, Jean-Michel; Raoult, Didier; Parola, Philippe

2013-02-01

193

Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry for Rapid Identification of Tick Vectors  

PubMed Central

A method for rapid species identification of ticks may help clinicians predict the disease outcomes of patients with tick bites and may inform the decision as to whether to administer postexposure prophylactic antibiotic treatment. We aimed to establish a matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) spectrum database based on the analysis of the legs of six tick vectors: Amblyomma variegatum, Rhipicephalus sanguineus, Hyalomma marginatum rufipes, Ixodes ricinus, Dermacentor marginatus, and Dermacentor reticulatus. A blind test was performed on a trial set of ticks to identify specimens of each species. Subsequently, we used MALDI-TOF MS to identify ticks obtained from the wild or removed from patients. The latter tick samples were also identified by 12S ribosomal DNA (rDNA) sequencing and were tested for bacterial infections. Ticks obtained from the wild or removed from patients (R. sanguineus, I. ricinus, and D. marginatus) were accurately identified using MALDI-TOF MS, with the exception of those ticks for which no spectra were available in the database. Furthermore, one damaged specimen was correctly identified as I. ricinus, a vector of Lyme disease, using MALDI-TOF MS only. Six of the 14 ticks removed from patients were found to be infected by pathogens that included Rickettsia, Anaplasma, and Borrelia spp. MALDI-TOF MS appears to be an effective tool for the rapid identification of tick vectors that requires no previous expertise in tick identification. The benefits for clinicians include the more targeted surveillance of patients for symptoms of potentially transmitted diseases and the ability to make more informed decisions as to whether to administer postexposure prophylactic treatment.

Yssouf, Amina; Flaudrops, Christophe; Drali, Rezak; Kernif, Tahar; Socolovschi, Cristina; Berenger, Jean-Michel; Raoult, Didier

2013-01-01

194

Analysis of protein glycation products by matrix-assisted laser desorption ionization time-of-flight mass spectrometry.  

PubMed

The term protein glycation summarizes non-enzymatic reactions between amino groups of proteins and sugars or sugar degradation products, leading to early glycation products (intact sugar attached) and advanced glycation end-products (AGEs). Protein glycation is involved in the progression of several diseases, such as diabetes, uremia, and atherosclerosis. However, qualitative and quantitative analysis of in vitro or in vivo glycated proteins is still a challenging task. The introduction of matrix-assisted laser desorption ionization time-of-flight technique (MALDI-TOF) changed mass spectrometry (MS) into a valuable tool for biomedical analysis, because the soft ionization procedure allows the measurement of proteins up to 100 kDa. In the last few years, MALDI-TOF-MS was applied to the investigation of glycation processes: the analyses of plasma proteins from diabetic or uremic patients allowed a precise determination of the average number of sugar residues attached to serum albumin or immunoglobulins of each patient. Thus, a more individualized diagnosis of each patient was achieved by MALDI-TOF-MS than by other diagnostic tools. In a similar way, the glycation rate of hemoglobin, isolated from diabetic blood and of beta-2-microglobulin isolated from amyloid plaques from uremic patients was determined. The application of MALDI-TOF-MS for in vitro studies revealed important new insights into glycation mechanisms. Whereas the measurement of the intact proteins allows the determination of the average glycation rate, peptide mapping prior to MALDI-TOF-MS can reveal the exact structures of the glycation products and the glycation site. Furthermore, when the unmodified peptide is used as internal standard, MALDI-TOF-MS can also be used for reliable, site specific relative quantification of defined glycation products. PMID:15279557

Kislinger, Thomas; Humeny, Andreas; Pischetsrieder, Monika

2004-08-01

195

Utilization of matrix-assisted laser desorption and ionization time-of-flight mass spectrometry for identification of infantile seborrheic dermatitis-causing Malassezia and incidence of culture-based cutaneous Malassezia microbiota of 1-month-old infants.  

PubMed

Matrix-assisted laser desorption and ionization time-of-flight mass spectrometry (MALDI-TOF-MS) has been utilized for identification of various microorganisms. Malassezia species, including Malassezia restricta, which is associated with seborrheic dermatitis, has been difficult to identify by traditional means. This study was performed to develop a system for identification of Malassezia species with MALDI-TOF-MS and to investigate the incidence and variety of cutaneous Malassezia microbiota of 1-month-old infants using this technique. A Malassezia species-specific MALDI-TOF-MS database was developed from eight standard strains, and the availability of this system was assessed using 54 clinical strains isolated from the skin of 1-month-old infants. Clinical isolates were cultured initially on CHROMagar Malassezia growth medium, and the 28S ribosomal DNA (D1/D2) sequence was analyzed for confirmatory identification. Using this database, we detected and analyzed Malassezia species in 68% and 44% of infants with and without infantile seborrheic dermatitis, respectively. The results of MALDI-TOF-MS analysis were consistent with those of rDNA sequencing identification (100% accuracy rate). To our knowledge, this is the first report of a MALDI-TOF-MS database for major skin pathogenic Malassezia species. This system is an easy, rapid and reliable method for identification of Malassezia. PMID:24387229

Yamamoto, Mikachi; Umeda, Yoshiko; Yo, Ayaka; Yamaura, Mariko; Makimura, Koichi

2014-02-01

196

ADAP-GC 2.0: deconvolution of coeluting metabolites from GC/TOF-MS data for metabolomics studies.  

PubMed

ADAP-GC 2.0 has been developed to deconvolute coeluting metabolites that frequently exist in real biological samples of metabolomics studies. Deconvolution is based on a chromatographic model peak approach that combines five metrics of peak qualities for constructing/selecting model peak features. Prior to deconvolution, ADAP-GC 2.0 takes raw mass spectral data as input, extracts ion chromatograms for all the observed masses, and detects chromatographic peak features. After deconvolution, it aligns components across samples and exports the qualitative and quantitative information of all of the observed components. Centered on the deconvolution, the entire data analysis workflow is fully automated. ADAP-GC 2.0 has been tested using three different types of samples. The testing results demonstrate significant improvements of ADAP-GC 2.0, compared to the previous ADAP 1.0, to identify and quantify metabolites from gas chromatography/time-of-flight mass spectrometry (GC/TOF-MS) data in untargeted metabolomics studies. PMID:22747237

Ni, Yan; Qiu, Yunping; Jiang, Wenxin; Suttlemyre, Kyle; Su, Mingming; Zhang, Wenchao; Jia, Wei; Du, Xiuxia

2012-08-01

197

N-(1-Naphthyl) Ethylenediamine Dinitrate: A New Matrix for Negative Ion MALDI-TOF MS Analysis of Small Molecules  

NASA Astrophysics Data System (ADS)

An organic salt, N-(1-naphthyl) ethylenediamine dinitrate (NEDN), with rationally designed properties of a strong UV absorbing chromophore, hydrogen binding and nitrate anion donors, has been employed as a matrix to analyze small molecules ( m/z < 1000) such as oligosaccharides, peptides, metabolites and explosives using negative ion matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Compared with conventional matrixes such as ?-cyano-4-hydroxycinnamic acid (CCA) and 2,5-dihydroxybenzoic acid (DHB), NEDN provides a significant improvement in detection sensitivity and yields very few matrix-associated fragment and cluster ions interfering with MS analysis. For low-molecular-weight saccharides, the lowest detection limit achieved ranges from 500 amol to 5 pmol, depending on the molecular weight and the structure of the analytes. Additionally, the mass spectra in the lower mass range ( m/z < 200) consist of only nitrate and nitric acid cluster ions, making the matrix particularly useful for structural identification of oligosaccharides by post-source decay (PSD) MALDI-MS. Such a characteristic is illustrated by using maltoheptaose as a model system. This work demonstrates that NEDN is a novel negative ion-mode matrix for MALDI-MS analysis of small molecules with nitrate anion attachment.

Chen, Rui; Chen, Suming; Xiong, Caiqiao; Ding, Xunlei; Wu, Chih-Che; Chang, Huan-Cheng; Xiong, Shaoxiang; Nie, Zongxiu

2012-09-01

198

Simultaneous determination nucleosides in marine organisms using ultrasound-assisted extraction followed by hydrophilic interaction liquid chromatography-electrospray ionization time-of-flight mass spectrometry.  

PubMed

A new method has been developed based on ultrasound-assisted extraction (UAE) followed by hydrophilic interaction chromatography (HILIC) and electrospray ionization time-of-flight mass spectrometry (ESI-TOF/MS) for the simultaneous determination of 16 nucleosides and nucleobases in medicinal extracts of various marine organisms. The separation was achieved on a Venusil HILIC column (250×4.6 mm id, 5 ?m) and gradient elution using a solution of acetonitrile and buffer (0.20% formic acid and 20 mmol/L ammonium acetate) as the mobile phase. Identification of the 16 target nucleosides and nucleobases was based on the retention time, UV spectra, and mass measurements of the protonated molecules ([M+H](+)) and main fragment ions (ESI-TOF/MS). In addition, non-target compounds of 2'-deoxyinosine and four other amino acids were also tentatively identified by ESI-TOF/MS. The 16 target compounds were quantified by HILIC-ESI-TOF/MS under optimized mass conditions. All calibration curves showed good linearity (r(2)>0.9951). The recoveries were 84.72-124.10%, and the limits of detection of the 16 target compounds were 0.6-130.0 ng/mL. The developed method was applied to quantify the target compounds in 15 batches of various marine organisms. The method has potential applicability for the identification and determination of highly polar and low-concentration active compounds in marine organisms. PMID:21837626

Zhao, Hengqiang; Chen, Junhui; Shi, Qian; Li, Xin; Zhou, Wenhui; Zhang, Daolai; Zheng, Li; Cao, Wei; Wang, Xiaoru; Lee, Frank Sen-Chun

2011-10-01

199

The power of hyphenated chromatography/time-of-flight mass spectrometry in public health laboratories.  

PubMed

Laboratories devoted to the public health field have to face the analysis of a large number of organic contaminants/residues in many different types of samples. Analytical techniques applied in this field are normally focused on quantification of a limited number of analytes. At present, most of these techniques are based on gas chromatography (GC) or liquid chromatography (LC) coupled to tandem mass spectrometry (MS/MS). Using these techniques only analyte-specific information is acquired, and many other compounds that might be present in the samples would be ignored. In this paper, we explore the potential of time-of-flight (TOF) MS hyphenated to GC or LC to provide additional information, highly useful in this field. Thus, all positives reported by standard reference targeted LC-MS/MS methods were unequivocally confirmed by LC-QTOF MS. Only 61% of positives reported by targeted GC-MS/MS could be confirmed by GC-TOF MS, which was due to its lower sensitivity as nonconfirmations corresponded to analytes that were present at very low concentrations. In addition, the use of TOF MS allowed searching for additional compounds in large-scope screening methodologies. In this way, different contaminants/residues not included in either LC or GC tandem MS analyses were detected. This was the case of the insecticide thiacloprid, the plant growth regulator paclobutrazol, the fungicide prochloraz, or the UV filter benzophenone, among others. Finally, elucidation of unknowns was another of the possibilities offered by TOF MS thanks to the accurate-mass full-acquisition data available when using this technique. PMID:22578112

Ibáñez, María; Portolés, Tania; Rúbies, Antoni; Muñoz, Eva; Muñoz, Gloria; Pineda, Laura; Serrahima, Eulalia; Sancho, Juan V; Centrich, Francesc; Hernández, Félix

2012-05-30

200

Ni speciation in tea infusions by monolithic chromatography--ICP-MS and Q-TOF-MS.  

PubMed

For humans, Ni is not considered to be an essential trace element. Its compounds, at levels present in foodstuffs and drinks, are generally considered to be safe for consumption, but for individuals who already suffer from contact allergy to Ni and may be subject to develop systemic reactions from its dietary ingestion, dietary exposure to Ni must be kept under control. Being the second most popular beverage, tea is a potential source of dietary Ni. Present knowledge on its speciation in tea infusions is poor. Therefore, complete speciation analysis, consisting of separation by liquid chromatography using a weak CIM DEAE-1 monolithic column, "on-line" detection by inductively coupled plasma mass spectrometry (ICP-MS) and "off-line" identification of ligands by hybrid quadrupole time-of-flight mass spectrometry (Q-TOF MS), was implemented for the first time to study Ni speciation in tea infusions. Total concentrations of Ni in dry leaves of white, green, oolong and black tea (Camellia sinensis) and flowers of herbal chamomile (Matricaria chamomilla) and hibiscus (Hibiscus sabdariffa) tea were determined after microwave digestion by ICP-MS. They lay between 1.21 and 14.4 mg kg(-1). Good agreement between the determined and the certified values of the Ni content in the standard reference material SRM 1573a tomato leaves confirmed the accuracy of the total Ni determination. During the infusion process, up to 85 % of Ni was extracted from tea leaves or flowers. Separation of Ni species was completed in 10 min by applying aqueous linear gradient elution with 0.6 mol L(-1) NH(4)NO(3). Ni was found to be present in the chromatographic fraction in which quinic acid was identified by Q-TOF in all the tea infusions analysed, which had pH values between 5.6 and 6.0. The only exception was the infusion of hibiscus tea with a pH of 2.7, where results of speciation analysis showed that Ni is present in its divalent ionic form. PMID:23232960

Š?an?ar, Janez; Zuliani, Tea; Žigon, Dušan; Mila?i?, Radmila

2013-02-01

201

Rapid laboratory diagnosis for respiratory infectious diseases by using MALDI-TOF mass spectrometry.  

PubMed

It is still challenging to prevent and treat respiratory infectious diseases. One critical step in the successful treatment of respiratory infections is rapid diagnosis by identifying the causative microorganisms in a timely fashion. However, traditional methods for identification of causative agents could not satisfy the need for rapid and accurate testing due to the limitations of technology-used. In recent years, matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS) has been validated and used for rapid identification of microorganism and for potential discovery of diseases associated biomarkers. We reviewed recent advances of MALDI-TOF-MS as the laboratory diagnostic tool for the rapid laboratory diagnosis of microorganisms associated with respiratory infectious diseases, with the focus on rapid identification of pathogenic bacteria and molecular markers discovery using MALDI-TOF-MS. With the advanced technologies such as MALDI-TOF, early and targeted therapies based on rapid identification of pathogens and could lead to quick and effective treatment of respiratory infections and better patient management. PMID:24822111

Wang, Yun F Wayne; Fu, Jianfeng

2014-05-01

202

Mass spectrometry for direct identification of biosignatures and microorganisms in Earth analogs of Mars  

NASA Astrophysics Data System (ADS)

Rover missions to Mars require portable instruments that use minimal power, require no sample preparation, and provide suitably diagnostic information to an Earth-based exploration team. In exploration of analog environments of Mars it is important to screen rapidly for the presence of biosignatures and microorganisms and especially to identify them accurately. Matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF-MS) has enormously contributed to the understanding of protein chemistry and cell biology. Without this technique proteomics would most likely not be the important discipline it is today. In this study, besides 'true' proteomics, MALDI-TOF-MS was applied for the analysis of microorganisms for their taxonomic characterization from its beginning. An approach was developed for direct analysis of whole bacterial cells without a preceding fractionation or separation by chromatography or electrophoresis on samples of bacteria from an Antarctic glacier. Supported by comprehensive databases, MALDI-TOF-MS-based identification could be widely accepted within only a few years for bacterial differentiation in Mars analogs and could be a technique of election for Mars exploration.

Garcia-Descalzo, Laura; García-López, Eva; Maria Moreno, Ana; Alcazar, Alberto; Baquero, Fernando; Cid, Cristina

2012-11-01

203

MALDI-TOF mass spectrometry confirms difficulties in separating species of the Avibacterium genus.  

PubMed

In the present study a well-characterized strain collection (n = 33) of Avibacterium species was investigated by matrix-assisted laser desorption ionization-time-of flight mass spectrometry (MALDI-TOF MS). The robustness of the currently available reference database (Bruker Biotyper 3.0) was tested to determine the degree of identification of these strains. Reproducible signal patterns were obtained from all strains. However, identification of most strains was only possible at genus level. Furthermore, two strains could not be identified by this method. Based on their protein spectra profiles, a MALDI main spectra dendrogram was created to determine their relationship. Most strains were closely related-for example, 26 strains formed cluster 1 including the type strains of Avibacterium volantium, Avibacterium gallinarum, Avibacterium endocarditidis and Avibacterium avium-while Avibacterium paragallinarum biovars 1 and 2 formed cluster 2 and, finally, strain 55000 remained on its own. The present MALDI-TOF MS results confirm recent findings that only certain isolates of Av. paragallinarum represent a well-defined species within the genus Avibacterium, making a taxonomic revision essential. To improve identification of Avibacterium at species level by MALDI-TOF MS, relevant reference strains were included in the newly created database and results are presented. In conclusion, Av. paragallinarum can be identified by MALDI/Biotyper and not the other species of the genus. PMID:24802229

Alispahic, Merima; Christensen, Henrik; Bisgaard, Magne; Hess, Michael; Hess, Claudia

2014-06-01

204

Rapid laboratory diagnosis for respiratory infectious diseases by using MALDI-TOF mass spectrometry  

PubMed Central

It is still challenging to prevent and treat respiratory infectious diseases. One critical step in the successful treatment of respiratory infections is rapid diagnosis by identifying the causative microorganisms in a timely fashion. However, traditional methods for identification of causative agents could not satisfy the need for rapid and accurate testing due to the limitations of technology-used. In recent years, matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS) has been validated and used for rapid identification of microorganism and for potential discovery of diseases associated biomarkers. We reviewed recent advances of MALDI-TOF-MS as the laboratory diagnostic tool for the rapid laboratory diagnosis of microorganisms associated with respiratory infectious diseases, with the focus on rapid identification of pathogenic bacteria and molecular markers discovery using MALDI-TOF-MS. With the advanced technologies such as MALDI-TOF, early and targeted therapies based on rapid identification of pathogens and could lead to quick and effective treatment of respiratory infections and better patient management.

Fu, Jianfeng

2014-01-01

205

Characterization of saccharide using high fluorescent 5-(((2-(carbohydrazino)methyl)thio)acetyl)-aminofluorescein tag by Capillary-HPLC-LIF and MALDI-TOF-MS.  

PubMed

The new approach to one-step derivatization of saccharide with 5-(((2-(carbohydrazino)methyl)thio)acetyl)-aminofluorescein (C356) was described. In this approach, high fluorescent C356 was applied to label saccharide to enhance the response of derivative saccharide and high sensitive capillary high performance liquid chromatography with laser-induced fluorescence (Capillary-HPLC-LIF) associated with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) was used to characterize C356 labeled saccharide. The effect of derivatization conditions was evaluated and discussed. The limit of detection (LOD) of neutral saccharide in our method attained the level of femtomolar. As a result, this method could be successfully applied to determine the structure of N-glycans of glycoprotein. PMID:24209334

Wang, Chaofeng; Gao, Mingxia; Huang, Zhi; Zhang, Xiangmin

2013-12-15

206

Profiling of soluble neutral oligosaccharides from treated biomass using solid phase extraction and LC-TOF MS.  

PubMed

Thermochemical pretreatments of cellulosic biomass are known to improve cell wall enzymatic digestibility, while simultaneously releasing substantial amounts of soluble oligosaccharides. Profiling of oligosaccharides released during pretreatment yields information essential for choosing glycosyl hydrolases necessary for cost-effective conversion of cellulosic biomass to desired biofuel/biochemical end-products. In this report we present a methodology for profiling of soluble neutral oligosaccharides released from ammonia fiber expansion (AFEX™)-pretreated corn stover. Our methodology employs solid phase extraction (SPE) enrichment of oligosaccharides using porous graphitized carbon (PGC), followed by high performance liquid chromatography (HPLC) separation using a polymeric amine based column and electrospray ionization time-of-flight mass spectrometry (ESI-TOF-MS). For structural elucidation on the chromatographic time scale, nonselective multiplexed collision-induced dissociation was performed for quasi-simultaneous acquisition of oligosaccharide molecular and fragment masses in a single analysis. These analyses revealed glucans up to degree of polymerization (DP) 22 without modifications. Additionally, arabinoxylans up to DP=6 were detected in pretreated biomass extracts (post-enzymatic digestion). Cross-ring fragment ion abundances were consistent with assignment of linkages between sugar units in glucans and also xylose backbone in arabinoxylans as 1-4 linkages. Comprehensive profiling of soluble oligosaccharides also demonstrated decreases in levels of acetate esters of arabinoxylan oligosaccharides with concomitant increases in nonacetylated oligosaccharides that were consistent with earlier observations of 85% release of acetate esters by AFEX™ pretreatment. PMID:23544634

Vismeh, Ramin; Humpula, James F; Chundawat, Shishir P S; Balan, Venkatesh; Dale, Bruce E; Jones, A Daniel

2013-05-15

207

RNase T1 mediated base-specific cleavage and MALDI-TOF MS for high-throughput comparative sequence analysis  

PubMed Central

Here we devise a new method for high-throughput comparative sequence analysis. The developed protocol comprises a homogeneous in vitro transcription/RNase cleavage system with the accuracy and data acquisition speed of matrix-assisted laser desorption/ionization coupled with time-of-flight mass spectrometry (MALDI-TOF MS). In summary, the target region is PCR amplified using primers tagged with promoter sequences of T7 or SP6 RNA polymerase. Using RNase T1, the in vitro transcripts are base-specifically cleaved at every G-position. This reaction results in a characteristic pattern of fragment masses that is indicative of the original target sequence. To enable high-throughput analysis, samples are processed with automated liquid handling devices and nanoliter amounts are dispensed onto SpectroCHIP arrays for reliable and homogeneous MALDI preparation. This system enables rapid automated comparative sequence analysis for PCR products up to 1 kb in length. We demonstrate the feasibility of the devised method for analysis of single nucleotide polymorphisms (SNPs) and pathogen identification.

Hartmer, Ralf; Storm, Niels; Boecker, Sebastian; Rodi, Charles P.; Hillenkamp, Franz; Jurinke, Christian; van den Boom, Dirk

2003-01-01

208

Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry-Based Functional Assay for Rapid Detection of Resistance against ?-Lactam Antibiotics  

PubMed Central

Resistance against ?-lactam antibiotics is a growing challenge for managing severe bacterial infections. The rapid and cost-efficient determination of ?-lactam resistance is an important prerequisite for the choice of an adequate antibiotic therapy. ?-Lactam resistance is based mainly on the expression/overexpression of ?-lactamases, which destroy the central ?-lactam ring of these drugs by hydrolysis. Hydrolysis corresponds to a mass shift of +18 Da, which can be easily detected by matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS). Therefore, a MALDI-TOF MS-based assay was set up to investigate different enterobacteria for resistance against different ?-lactam antibiotics: ampicillin, piperacillin, cefotaxime, ceftazidime, ertapenem, imipenem, and meropenem. ?-Lactamases are enzymes that have a high turnover rate. Therefore, hydrolysis can be detected by MALDI-TOF MS already after a few hours of incubation of the bacteria to be tested with the given antibiotic. The comparison of the MS-derived data with the data from the routine procedure revealed identical classification of the bacteria according to sensitivity and resistance. The MALDI-TOF MS-based assay delivers the results on the same day. The approved routine procedures require at least an additional overnight incubation.

Sparbier, Katrin; Schubert, Soren; Weller, Ulrich; Boogen, Christiane

2012-01-01

209

Interlaboratory Comparison of Intact-Cell Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry Results for Identification and Differentiation of Brucella spp.  

PubMed Central

Classical microbiological diagnosis of human brucellosis is time-consuming, hazardous, and subject to variable interpretation. Intact-cell matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) was evaluated for the routine identification of Brucella spp. Analysis of mass peak patterns allowed accurate identification to the genus level. However, statistical models based on peak intensities were needed for definite species differentiation. Interlaboratory comparison confirmed the reproducibility of the results.

Karger, Axel; Melzer, Falk; Timke, Markus; Bettin, Barbara; Kostrzewa, Markus; Nockler, Karsten; Hohmann, Angelika; Tomaso, Herbert; Neubauer, Heinrich

2013-01-01

210

Hybrid Ion-Detector/Data-Acquisition System for a TOF-MS  

NASA Technical Reports Server (NTRS)

A modified ion-detector/data-acquisition system has been devised to increase the dynamic range of a time-of-flight mass spectrometer (TOF-MS) that, previously, included a microchannel-plate detector and a data-acquisition system based on counting pulses and time-tagging them by use of a time-to-digital converter (TDC). The dynamic range of the TOF-MS was limited by saturation of the microchannel plate detector, which can handle no more than a few million counts per second. The modified system includes (1) a combined microchannel plate/discrete ion multiplier and (2) a hybrid data-acquisition system that simultaneously performs analog current or voltage measurements and multianode single-ion-pulse-counting time-of-flight measurements to extend the dynamic range of a TDC into the regime in which a mass peak comprises multiple ions arriving simultaneously at the detector. The multianode data are used to determine, in real time, whether the detector is saturated. When saturation is detected, the data-acquisition system selectively enables circuitry that simultaneously determines the ion-peak intensity by measuring the time profile of the analog current or voltage detector-output signal.

Burton, William D., Jr.; Schultz, J. Albert; Vaughn, Valentine; McCully, Michael; Ulrich, Steven; Egan, Thomas F.

2006-01-01

211

Development of soft extraction method for structural characterization of boreal forest soil proteins with MALDI-TOF/MS  

NASA Astrophysics Data System (ADS)

Nitrogen (N) is usually the nutrient restricting productivity in boreal forests. Forest soils contain a great amount of nitrogen, but only a small part of it is in mineral form. Most part of soil N is bound in the structures of different organic compounds such as proteins, peptides, amino acids and more stabilized, refractory compounds. Due to the fact that soil organic N has a very important role in soil nutrient cycling and in plant nutrition, there is a need for more detailed knowledge of its chemistry in soil. Conventional methods to extract and analyze soil organic N are usually very destructive for structures of higher molecular weight organic compounds, such as proteins. The aim of this study was to characterize proteins extracted from boreal forest soil by "soft" extraction methods in order to maintain their molecular structure. The organic layer (F) from birch forest floor containing 78% of organic matter was sieved, freeze dried, pulverized, and extracted with a citrate or phosphate buffer (pH 6 or 8). Sequential extraction with the citrate or phosphate buffer and an SDS buffer (pH 6.8), slightly modified from the method of Chen et al. (2009, Proteomics 9: 4970-4973), was also done. Proteins were purified from the soil extract by extraction with buffered phenol and precipitated with methanol + 0.1M ammonium acetate at -20°C. Characterization of proteins was performed with matrix assisted laser desorption ionization - time-of-flight mass spectrometry (MALDI-TOF/MS) and the concentration of total proteins was measured using Bradford's method. Bovine serum albumin (BSA) was used as a positive control in the extractions and as a standard protein in Bradford's method. Our results showed that sequential extraction increased the amount of extracted proteins compared to the extractions without the SDS-buffer; however, it must be noted that the use of SDS-buffer very probably increased denaturization of proteins. Purification of proteins from crude soil extracts by phenol extraction was essential prior to measurement of total proteins; there seemed to be a lot of compounds in crude soil extracts that interfere with the analysis of total proteins, causing overestimation in protein concentration. pH of the buffer solution did not seem to be very crucial for the extractability of soil natural proteins, but at the higher pH, the amount of interfering compounds increased. However, the recovery of BSA added was clearly higher at the higher pH. When the protein precipitates were analyzed with MALDI-TOF/MS, a large curve, most likely formed from wide peaks of several compounds, indicate that most of the compounds in the precipitate were <15 kDa or ~20-50 kDa in molecular weight. It seems that in order to identify individual proteins from mass spectra, a separation of compounds with varying molecular weight is needed before the MALDI-TOF/MS analysis. Due to the fact that a relatively high amount of BSA added was not recovered by the extractions and that the intensity of the signals observed in mass spectra was low, it is questionable whether it is possible to extract soil natural proteins effectively from soils containing a high amount of organic matter without destructing the structures of proteins.

Kanerva, Sanna; Ketola, Raimo A.; Kitunen, Veikko; Smolander, Aino; Kotiaho, Tapio

2010-05-01

212

Urinary Metabolites of Isoliquiritigenin in Wistar Rats using UHPLC–TOF–MS-based Xenometabolomics  

Microsoft Academic Search

Isoliquiritigenin, a chalcone found in licorice root and many other plants, has shown potential antioxidant, estrogenic and\\u000a antitumor activities. The present study was to investigate urinary metabolism of isoliquiritigenin in Wistar rats by ultra-high\\u000a pressure liquid chromatography coupled to electrospray ionization TOF–MS (UHPLC–TOF–MS)-based xenometabolomics. Urine samples\\u000a were collected before and after oral administration of isoliquiritigenin, and analyzed by UHPLC–TOF–MS. After

Guangguo Tan; Ziyang Lou; Xing Dong; Wuhong Li; Wenting Liao; Zhenyu Zhu; Yifeng Chai

2011-01-01

213

Qualitative and quantitative analyses of bioactive secolignans from folk medicinal plant Peperomia dindygulensis using UHPLC-UV/Q-TOF-MS.  

PubMed

Peperomia dindygulensis, with secolignans (SLs) as major bioactive constituents, is a commonly used traditional folk medicine in mainland China for treatment of stomach, liver, mammary, and esophageal cancers. However, to date, there is no method available for the qualitative and quantitative analyses of SLs in this medicinal plant. The purpose of this study was to establish a sensitive, selective, and reproducible method for rapidly profiling, identifying, and determining SLs in the whole plant of P. dindygulensis. Ultra high-performance liquid chromatography (UHPLC) coupled with ultraviolet detector (UV) and quadrupole tandem time-of-flight mass spectrometry (Q-TOF-MS) were used for this analyses. The fragmentation behaviors of different types of SLs were described. A total of thirteen SLs, including two new derivatives, were identified or tentatively characterized in P. dindygulensis samples. In addition, seven major SLs in herbal samples from different regions in China were successfully determined. The method developed in this study is suitable for the qualitative and quantitative analyses of SLs in P. dindygulensis, and may be applicable for determining or identifying SLs from other Pepermia genus plants. PMID:24531004

Wang, Xin-Zhi; Liang, Jing-Yu; Wen, Hong-Mei; Shan, Chen-Xiao; Liu, Rui

2014-06-01

214

Enhanced In-Source Fragmentation in MALDI-TOF-MS of Oligonucleotides Using 1,5-Diaminonapthalene  

NASA Astrophysics Data System (ADS)

The capability to rapidly and confidently determine or confirm the sequences of short oligonucleotides, including native and chemically-modified DNA and RNA, is important for a number of fields. While matrix-assisted laser desorption/ionization (MALDI) time-of-flight (TOF) mass spectrometry (MS) has been used previously to sequence short oligonucleotides, the typically low fragmentation efficiency of in-source or post-source decay processes necessitates the accumulation of a large number of spectra, thus limiting the throughput of these methods. Here we introduce a novel matrix, 1,5-diaminonapthalene (DAN), for facile in-source decay (ISD) of DNA and RNA molecular anions, which allows for rapid sequence confirmation. d-, w-, and y-series ions are prominent in the spectra, complementary to the ( a-B)- and w- ions that are typically produced by MALDI post-source decay (PSD). Results are shown for several model DNA and RNA oligonucleotides, including combinations of DAN-induced fragmentation with true tandem TOF MS (MS/MS) for pseudo-MS3 and "activated-ion PSD."

Hagan, Nathan A.; Smith, Christine A.; Antoine, Miquel D.; Lin, Jeffrey S.; Feldman, Andrew B.; Demirev, Plamen A.

2012-04-01

215

MALDI-TOF MS analysis of cellodextrins and xylo-oligosaccharides produced by hindgut homogenates of Reticulitermes santonensis.  

PubMed

Hindgut homogenates of the termite Reticulitermes santonensis were incubated with carboxymethyl cellulose (CMC), crystalline celluloses or xylan substrates. Hydrolysates were analyzed with matrix-assisted laser desorption/ionization coupled to time-of-flight mass spectrometry (MALDI-TOF MS). The method was first set up using acid hydrolysis analysis to characterize non-enzymatic profiles. Commercial enzymes of Trichoderma reesei or T. longibrachiatum were also tested to validate the enzymatic hydrolysis analysis. For CMC hydrolysis, data processing and visual display were optimized to obtain comprehensive profiles and allow rapid comparison and evaluation of enzymatic selectivity, according to the number of substituents of each hydrolysis product. Oligosaccharides with degrees of polymerization (DPs) ranging from three to 12 were measured from CMC and the enzymatic selectivity was demonstrated. Neutral and acidic xylo-oligosaccharides with DPs ranging from three to 11 were measured from xylan substrate. These results are of interest for lignocellulose biomass valorization and demonstrated the potential of termites and their symbiotic microbiota as a source of interesting enzymes for oligosaccharides production. PMID:24731986

Brasseur, Catherine; Bauwens, Julien; Tarayre, Cédric; Mattéotti, Christel; Thonart, Philippe; Destain, Jacqueline; Francis, Frédéric; Haubruge, Eric; Portetelle, Daniel; Vandenbol, Micheline; Focant, Jean-François; De Pauw, Edwin

2014-01-01

216

Identification and characterization of a new IgE-binding protein in mackerel ( Scomber japonicus) by MALDI-TOF-MS  

NASA Astrophysics Data System (ADS)

As fish is one source of the `big eight' food allergens, the prevalence of fish allergy has increased over the past few years. In order to better understand fish allergy, it is necessary to identify fish allergens. Based on the sera from fish-allergenic patients, a 28 kDa protein from local mackerel ( Scomber japonicus), which has not been reported as a fish allergen, was found to be reactive with most of the patients' sera. The 28 kDa protein was analyzed by MALDI-TOF-MS (Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry). Mascot search in NCBI database (Date: 08/07/2010) showed that the top protein matched, i.e. triosephosphate isomerase (TPI) from Xiphophorus maculatus and Poecilia reticulata, had a mowse (molecular weight search) score of 98. In addition, TPI from Epinephelus coioides also matched this mackerel protein with a mowse score of 96. Because TPI is considered as an allergen in other non-fish organisms, such as lychee, wheat, latex, archaeopotamobius ( Archaeopotamobius sibiriensis) and crangon ( Crangon crangon), we consider that it may also be an allergen in mackerel.

Wang, Bangping; Li, Zhenxing; Zheng, Lina; Liu, Yixuan; Lin, Hong

2011-03-01

217

Metabolomics driven analysis of artichoke leaf and its commercial products via UHPLC-q-TOF-MS and chemometrics.  

PubMed

The demand to develop efficient and reliable analytical methods for the quality control of herbal medicines and nutraceuticals is on the rise, together with an increase in the legal requirements for safe and consistent levels of active principles. Here, we describe an ultra-high performance liquid chromatography method (UHPLC) coupled with quadrupole high resolution time of flight mass spectrometry (qTOF-MS) analysis for the comprehensive measurement of metabolites from three Cynara scolymus (artichoke) cultivars: American Green Globe, French Hyrious, and Egyptian Baladi. Under optimized conditions, 50 metabolites were simultaneously quantified and identified including: eight caffeic acid derivatives, six saponins, 12 flavonoids and 10 fatty acids. Principal component analysis (PCA) was used to define both similarities and differences among the three artichoke leaf cultivars. In addition, batches from seven commercially available artichoke market products were analysed and showed variable quality, particularly in caffeic acid derivatives, flavonoid and fatty acid contents. PCA analysis was able to discriminate between various preparations, including differentiation between various batches from the same supplier. To the best of our knowledge, this study provides the first approach utilizing UHPLC-MS based metabolite fingerprinting to reveal secondary metabolite compositional differences in artichoke leaf extracts. PMID:23902683

Farag, Mohamed A; El-Ahmady, Sherweit H; Elian, Fatma S; Wessjohann, Ludger A

2013-11-01

218

Two Classifiers Based on Serum Peptide Pattern for Prediction of HBV-Induced Liver Cirrhosis Using MALDI-TOF MS  

PubMed Central

Chronic infection with hepatitis B virus (HBV) is associated with the majority of cases of liver cirrhosis (LC) in China. Although liver biopsy is the reference method for evaluation of cirrhosis, it is an invasive procedure with inherent risk. The aim of this study is to discover novel noninvasive specific serum biomarkers for the diagnosis of HBV-induced LC. We performed bead fractionation/MALDI-TOF MS analysis on sera from patients with LC. Thirteen feature peaks which had optimal discriminatory performance were obtained by using support-vector-machine-(SVM-) based strategy. Based on the previous results, five supervised machine learning methods were employed to construct classifiers that discriminated proteomic spectra of patients with HBV-induced LC from those of controls. Here, we describe two novel methods for prediction of HBV-induced LC, termed LC-NB and LC-MLP, respectively. We obtained a sensitivity of 90.9%, a specificity of 94.9%, and overall accuracy of 93.8% on an independent test set. Comparisons with the existing methods showed that LC-NB and LC-MLP held better accuracy. Our study suggests that potential serum biomarkers can be determined for discriminating LC and non-LC cohorts by using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. These two classifiers could be used for clinical practice in HBV-induced LC assessment.

Song, Wei; Li, Ai-Ling; Wang, Na

2013-01-01

219

Metabonomic analysis of the toxic effects of TM208 in rat urine by HPLC-ESI-IT-TOF/MS.  

PubMed

4-Methylpiperazine-1-carbodithiocacid-3-cyano-3,3-diphenylpropyl ester hydrochloride (TM208) was a potential antitumor new drug with many preliminary studies in pharmacokinetics and pharmacodynamics. This study aims to determine whether TM208 elicits toxic effects by metabonomics for the first time. Sprague Dawley (SD) rats were exposured to TM208 at a single therapeutic dose (100mg/kg/d) for 5 days, metabolites of urine samples from both control and TM208-treated groups were analyzed using high performance liquid chromatography-electrospray ionization source in combination with hybrid ion trap and high-resolution time-of-flight mass spectrometry (HPLC-ESI-IT-TOF/MS). Metabolites such as aminoadipic acid, creatine, gluconic acid, cis-aconitic acid, succinic acid and pipecolic acid which changed significantly, were identified as potential biomarkers. These results suggest that the changes in urinary metabolites of rats after exposure to TM208 were mainly related to energy metabolism and amino acid metabolism, which may be helpful to further understand the mechanism of TM208 toxicity in rats and a new drug development. PMID:24747524

Yang, Haisong; Lin, Wensi; Zhang, Jianmei; Lin, Weiwei; Xu, Peng; Li, Jing; Ling, Xiaomei

2014-05-15

220

Differentiation in MALDI-TOF MS and FTIR spectra between two pathovars of Xanthomonas oryzae.  

PubMed

Xanthomonas oryzae pv. oryzae (Xoo) and Xanthomonas oryzae pv. oryzicola (Xoc) strains are closely related phenotypically and genetically, which make it difficult to differentiate between the two pathovars based on phenotypic and DNA-based methods. In this study, a fast and accurate method was developed based on the differences in MALDI-TOF MS and FTIR spectra between the two pathovars. MALDI-TOF MS analysis revealed that 9 and 10 peaks are specific to Xoo and Xoc, respectively, which can be used as biomarkers to identify and differentiate the two closely related pathovars. Furthermore, FTIR analysis showed that there is a significant difference in both the band frequencies and absorption intensity of various functional groups between the two pathovars. In particular, the 6 peaks at 3433, 2867, 1273, 1065, 983 and 951cm(-1) were specific to the Xoo strains, while one peak at 1572cm(-1) was specific to the Xoc strains. Overall, this study gives the first attempt to identify and differentiate the two pathovars of X. oryzae based on mass and FTIR spectra, which will be helpful for the early detection and prevention of the two rice diseases caused by both X. oryzae pathovars. PMID:24996215

Ge, Mengyu; Li, Bin; Wang, Li; Tao, Zhongyun; Mao, Shengfeng; Wang, Yangli; Xie, Guanlin; Sun, Guochang

2014-12-10

221

Rapid detection of GM1 ganglioside in cerebrospinal fluid in dogs with GM1 gangliosidosis using matrix-assisted laser desorption ionization time-of-flight mass spectrometry.  

PubMed

The concentration of GM1 (monosialotetrahexosyl ganglioside) in cerebrospinal fluid (CSF) is markedly increased in dogs with GM1 gangliosidosis due to GM1 accumulation in the central nervous system and leakage to the CSF. The present study established a rapid and simple method for detection of accumulated GM1 in the CSF in dogs with GM1 gangliosidosis using matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI TOF MS) and discusses the usefulness of this method for the rapid diagnosis and/or high-risk screening of this disease in domestic animals. Cerebrospinal fluid was collected from normal dogs and 4- to 11-month-old Shiba dogs with GM1 gangliosidosis. The MALDI TOF MS analysis was carried out in combination with a special sample plate and a simple desalting step on the plate. Specific signs of GM1 could be detected in the standard GM1 solutions at concentrations of 50 nmol/l or more. The signs were also clearly detected in CSF (131-618 nmol/l) in affected dogs, but not in normal canine CSF (12 ± 5 nmol/l, mean ± standard deviation). The results demonstrated that MALDI TOF MS can detect GM1 accumulated in canine CSF even in the early stage of the disease. In conclusion, the rapid detection of increased CSF GM1 using MALDI TOF MS is a useful method for diagnosis and/or screening for canine GM1 gangliosidosis. PMID:22362802

Satoh, Hiroyuki; Yamauchi, Toyofumi; Yamasaki, Masahiro; Maede, Yoshimitsu; Yabuki, Akira; Chang, Hye-Sook; Asanuma, Taketoshi; Yamato, Osamu

2011-11-01

222

Identification of Mycobacteria from Solid and Liquid Media by Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry in the Clinical Laboratory  

PubMed Central

Mycobacteria cause significant morbidity in humans. Rapid and accurate mycobacterial identification is important for improvement of patient outcomes. However, identification may be challenging due to the slow and fastidious growth of mycobacteria. Several diagnostic methods, such as biochemical, sequencing, and probe methods, are used for mycobacterial identification. We compared the matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) Biotyper system (Bruker Daltonics) to 16S rRNA/hsp65 sequencing and/or DNA probes (Gen-Probe) for mycobacterial identification. One hundred seventy-eight mycobacterial isolates grown on solid and/or broth medium were included in the study. MALDI-TOF MS identified 93.8% of the mycobacteria isolates accurately to the species level and 98.3% to the genus level, independent of the type of medium used for isolation. The identification of mycobacteria directly from cultures using MALDI-TOF MS allows for precise identification in an hour compared to traditional biochemical and phenotypic methods that can take weeks or probes and sequencing that may take a few hours. Identification by MALDI-TOF MS potentially reduces the turnaround time and cost, thereby saving resources within the health care system.

Kamboj, Kamal; Pancholi, Preeti

2013-01-01

223

Rapid identification of bacteria in positive blood culture by matrix-assisted laser desorption ionization time-of-flight mass spectrometry.  

PubMed

Blood culture is probably the most significant specimen used for the diagnosis of bacterial infections, especially for bloodstream infections. In the present study, we compared the resin-containing BD BACTEC™ Plus-Aerobic (Becton Dickinson), non-charcoal-containing BacT/Alert(®) SA (bioMérieux), and charcoal-containing BacT/Alert(®) FA (bioMérieux) blood culture bottles with direct identification by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). A total of 103 bacterial isolates, from clinical blood cultures, representing the most frequent 13 genera and 24 species were examined. Bacteria were extracted from positive blood culture broth by density centrifugation and then subjected to identification by MALDI-TOF MS using two different volumes and chemical treatments. Overall, correct identification by MALDI-TOF MS was obtained for the BD BACTEC™ Plus-Aerobic, BacT/Alert(®) SA, and BacT/Alert(®) FA blood culture bottles in 72%, 45.6%, and 23%, respectively, for gram-negative bacteria in 86.6%, 69.2%, and 47.1%, respectively, and for gram-positive bacteria in 60.0%, 28.8%, and 5.4%, respectively. The lack of identification was observed mainly with viridans streptococci. Depending on the blood culture bottles used in routine diagnostic procedures and the protocol for bacterial preparation, the applied MALDI-TOF MS represents an efficient and rapid method for direct bacterial identification. PMID:21698496

Schmidt, V; Jarosch, A; März, P; Sander, C; Vacata, V; Kalka-Moll, W

2012-03-01

224

Identification of pathogens from blood culture bottles in spiked and clinical samples using matrix-assisted laser desorption ionization time-of-flight mass-spectrometry analysis  

PubMed Central

Background Blood stream infections significantly contribute to mortality. An early most appropriate antimicrobial therapy is crucial for a favourable outcome of the patient. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) may speed up the diagnostic of causative micro organisms. Findings MALDI-TOF MS using the SARAMIS database was applied to 37 spiked blood culture samples. Identification rates of spiked samples were as follows: The species level was determined in 16 of 21 (76.2%) Gram negative bacteria and in 11 of 13 (84.6%) Gram positive bacteria. Genus level only was determined in additional 2 Gram negative and for the 2 Gram positive strains. Yeast species could not be identified. MALDI-TOF MS was also compared to cultured-based results in standard routine diagnostic. Identification rates of patient samples were as follows: The species level was determined in 41 of 47 (87.2%) Gram negative bacteria and in 63 of 123 (51.2%) Gram positive bacteria. Genus level only was determined in additional 2 Gram negative bacteria. Once again no yeasts were identified. A prolonged incubation of BC bottles for 16 hours after primary positive alert did not influence the concentration of bacteria and identification rates. Conclusions The SARAMIS database used in our experiments mainly confirms previous findings that were obtained with the MALDI-TOF MS BRUKER system by others.

2014-01-01

225

High resolution detection of high mass proteins up to 80,000 Da via multifunctional CdS quantum dots in laser desorption/ionization mass spectrometry.  

PubMed

CdS quantum dots (? 5 nm) are used as multifunctional nanoprobes as an effective matrix for large proteins, peptides and as affinity probes for the enrichment of tryptic digest proteins (lysozyme, myoglobin and cytochrome c) in laser desorption/ionization time-of-flight mass spectrometry (LDI-TOF MS). The use of CdS quantum dots (CdS QDs) as the matrix allows acquisition of high resolution LDI mass spectra for large proteins (5000-80,000 Da). The enhancement of mass resolution is especially notable for large proteins such as BSA, HSA and transferrin (34-49 times) when compared with those obtained by using SA as the matrix. This technique demonstrates the potentiality of LDI-TOF-MS as an appropriate analytical tool for the analysis of high-molecular-weight biomolecules with high mass resolution. In addition, CdS QDs are also used as matrices for background-free detection of small biomolecules (peptides) and as affinity probes for the enrichment of tryptic digest proteins in LDI-TOF-MS. PMID:21035661

Ke, Yaotang; Kailasa, Suresh Kumar; Wu, Hui-Fen; Chen, Zhen-Yu

2010-11-15

226

MALDI-TOF MS Enables the Rapid Identification of the Major Molecular Types within the Cryptococcus neoformans/C. gattii Species Complex  

PubMed Central

Background The Cryptococcus neoformans/C. gattii species complex comprises two sibling species that are divided into eight major molecular types, C. neoformans VNI to VNIV and C. gattii VGI to VGIV. These genotypes differ in host range, epidemiology, virulence, antifungal susceptibility and geographic distribution. The currently used phenotypic and molecular identification methods for the species/molecular types are time consuming and expensive. As Matrix-Assisted Laser Desorption Ionization-Time-of-Flight Mass Spectrometry (MALDI-TOF MS) offers an effective alternative for the rapid identification of microorganisms, the objective of this study was to examine its potential for the identification of C. neoformans and C. gattii strains at the intra- and inter-species level. Methodology Protein extracts obtained via the formic acid extraction method of 164 C. neoformans/C. gattii isolates, including four inter-species hybrids, were studied. Results The obtained mass spectra correctly identified 100% of all studied isolates, grouped each isolate according to the currently recognized species, C. neoformans and C. gattii, and detected potential hybrids. In addition, all isolates were clearly separated according to their major molecular type, generating greater spectral differences among the C. neoformans molecular types than the C. gattii molecular types, most likely reflecting a closer phylogenetic relationship between the latter. The number of colonies used and the incubation length did not affect the results. No spectra were obtained from intact yeast cells. An extended validated spectral library containing spectra of all eight major molecular types was established. Conclusions MALDI-TOF MS is a rapid identification tool for the correct recognition of the two currently recognized human pathogenic Cryptococcus species and offers a simple method for the separation of the eight major molecular types and the detection of hybrid strains within this species complex in the clinical laboratory. The obtained mass spectra provide further evidence that the major molecular types warrant variety or even species status.

Firacative, Carolina; Trilles, Luciana; Meyer, Wieland

2012-01-01

227

Functionalized quantum dots with dopamine dithiocarbamate as the matrix for the quantification of efavirenz in human plasma and as affinity probes for rapid identification of microwave tryptic digested proteins in MALDI-TOF-MS.  

PubMed

Functionalized quantum dots with dopamine dithiocarbamate (QDs-DDTC) were utilized for the first time as an efficient material for the quantification of efavirenz in human plasma of HIV infected patients and rapid identification of microwave tryptic digest proteins (cytochrome c, lysozyme and BSA) by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). The synthesized QDs-DDTC was characterized by using spectroscopic (UV-visible, FT-IR and (1)H NMR) and microscopic (SEM and TEM) techniques. Functionalized QDs-DDTC exhibited a high desorption/ionization efficiency for the rapid quantification of small molecules (efavirenz, tobramycin and aspartame) at low-mass region. QDs-DDTC has well ability to trap target species, and capable to transfer laser energy for efficient desorption/ionization of analytes with background-free detection. The use of QDs-DDTC as a matrix provided good linearity for the quantification of small molecules (R(2)=~0.9983), with good reproducibility (RSD<10%), in the analysis of efavirenz in the plasma of HIV infected patients by the standard addition method. We also demonstrated that the use of functionalized QDs-DDTC as affinity probes for the rapid identification of microwave tryptic digested proteins (cytochrome c, lysozyme and BSA) by MALDI-TOF-MS. QDs-DDTC-based MALDI-TOF-MS approach provides simplicity, rapidity, accuracy, and precision for the determination of efavirenz in human plasma of HIV infected patients and rapid identification of microwave tryptic digested proteins. This new material presents a marked advance in the development of matrix-free mass spectrometric methods for the rapid and precise quantitative determination of a variety of molecules. This article is part of a Special Issue entitled: Proteomics: The clinical link. PMID:22202183

Kailasa, Suresh Kumar; Wu, Hui-Fen

2012-06-01

228

Species identification of clinical isolates of Bacteroides by matrix-assisted laser-desorption/ionization time-of-flight mass spectrometry.  

PubMed

Bacteroides fragilis and related species are important human pathogens involved in mixed infections of different origins. The B. fragilis group isolates are phenotypically very similar, grow more slowly than aerobic bacteria and, accordingly, are frequently misidentifed with classical or automated phenotypical identification methods. Recent taxonomic changes and new species accepted as members of the Bacteroides genus are not included in the different databases of commercially available identification kits. The use of matrix-assisted laser-desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) was therefore evaluated for the species identification of 277 clinical isolates of the Bacteroides genus. Species identification was carried out with MALDI Bruker Daltonik Biotyper software (Bruker Daltonik GmbH, Bremen, Germany) by comparing the mass spectrum of each strain with the mass spectra of the 3260 reference strains currently available. The results of conventional phenotypical identification of the isolates were used as a reference. 16S rRNA gene sequencing was performed for a selection of the strains that gave discrepant results and for all those inconclusively identified by MALDI-TOF MS; 270 isolates (97.5%) were unequivocally identified [log(score) >/=2.0] by comparison with the reference strains present in the MALDI Biotyper database. Of the 23 isolates for which the MALDI-TOF MS species identification differed from the conventional phenotypical identification, 11 were sequenced. The sequencing data confirmed the MALDI-TOF MS result in ten cases and, for the remaining isolate, the sequencing data did not lead to the determination of the species, but only to that of the genus (Bacteroides sp.). The discriminating power and identification accuracy of MALDI-TOF MS proved to be superior to that of biochemical testing for Bacteroides thetaiotaomicron, Bacteroides ovatus and Bacteroides uniformis. PMID:19438622

Nagy, E; Maier, T; Urban, E; Terhes, G; Kostrzewa, M

2009-08-01

229

Matrix-Assisted Laser Desorption Ionization - Time of Flight Mass Spectrometry: An Emerging Tool for the Rapid Identification of Mosquito Vectors  

PubMed Central

Background The identification of mosquito vectors is typically based on morphological characteristics using morphological keys of determination, which requires entomological expertise and training. The use of protein profiling by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS), which is increasingly being used for the routine identification of bacteria, has recently emerged for arthropod identification. Methods To investigate the usefulness of MALDI-TOF-MS as a mosquito identification tool, we tested protein extracts made from mosquito legs to create a database of reference spectra. The database included a total of 129 laboratory-reared and field-caught mosquito specimens consisting of 20 species, including 4 Aedes spp., 9 Anopheles spp., 4 Culex spp., Lutzia tigripes, Orthopodomyia reunionensis and Mansonia uniformis. For the validation study, blind tests were performed with 76 specimens consisting of 1 to 4 individuals per species. A cluster analysis was carried out using the MALDI-Biotyper and some spectra from all mosquito species tested. Results Biomarker mass sets containing 22 and 43 masses have been detected from 100 specimens of the Anopheles, Aedes and Culex species. By carrying out 3 blind tests, we achieved the identification of mosquito vectors at the species level, including the differentiation of An. gambiae complex, which is possible using MALDI-TOF-MS with 1.8 as the cut-off identification score. A cluster analysis performed with all available mosquito species showed that MALDI-Biotyper can distinguish between specimens at the subspecies level, as demonstrated for An gambiae M and S, but this method cannot yet be considered a reliable tool for the phylogenetic study of mosquito species. Conclusions We confirmed that even without any specific expertise, MALDI-TOF-MS profiling of mosquito leg protein extracts can be used for the rapid identification of mosquito vectors. Therefore, MALDI-TOF-MS is an alternative, efficient and inexpensive tool that can accurately identify mosquitoes collected in the field during entomological surveys.

Yssouf, Amina; Socolovschi, Cristina; Flaudrops, Christophe; Ndiath, Mamadou Ousmane; Sougoufara, Seynabou; Dehecq, Jean-Sebastien; Lacour, Guillaume; Berenger, Jean-Michel; Sokhna, Cheikh Sadibou; Raoult, Didier; Parola, Philippe

2013-01-01

230

Glycosylation characterization of Human IgA1 with differential deglycosylation by UPLC-ESI TOF MS.  

PubMed

Differential deglycosylation was introduced as an effective technique to characterize glycosylation in glycoprotein containing both N-linked and O-linked glycans at both protein and peptide levels. Human IgA1 was used as a model glycoprotein to demonstrate this technique. The glycans attached to Human IgA1 were removed from their attachment sites by an array of enzymes. After reduction by DTT, the resulting deglycoproteins were analyzed by UPLC-ESI TOF MS to estimate the numbers of N-glycan and O-glycan sites through differential masses. The deglycoproteins and unmodified glycoprotein were further digested to deglycopeptide through trypsin digestion. The glycopeptides and deglycopeptides were identified by UPLC-ESI TOF MS. Two N-glycan and four O-glycan sites were identified and confirmed at peptide levels. These results matched those from deglycoproteins. The N-glycosylation site and N-glycan sequence confirmation were also demonstrated in this study. PMID:21752569

Klapoetke, Song C; Zhang, Jian; Becht, Steven

2011-11-01

231

Identification of European mosquito species by MALDI-TOF MS.  

PubMed

MALDI-TOF MS profiling has proved to be efficient for arthropod identification at the species level. However, prior to entomological monitoring, the reference spectra database should cover relevant species. Here, 74 specimens were field-collected from 11 mosquito species captured in two distinct European areas and used either to increment our database or for blind tests. Misidentification was not noted, underlining the power of this approach. Nevertheless, three out of the 26 specimens used for the blind test did not reach the significant identification threshold value set, attributed to lower spectral quality. In the future, the quality control spectra parameters need to be defined to avoid not achieving significant threshold identification. PMID:24737398

Yssouf, Amina; Parola, Philippe; Lindström, Anders; Lilja, Tobias; L'Ambert, Grégorie; Bondesson, Ulf; Berenger, Jean-Michel; Raoult, Didier; Almeras, Lionel

2014-06-01

232

Control of strobilurin fungicides in wheat using direct analysis in real time accurate time-of-flight and desorption electrospray ionization linear ion trap mass spectrometry.  

PubMed

Ambient mass spectrometry has been used for the analysis of strobilurin residues in wheat. The use of this novel, challenging technique, employing a direct analysis in a real time (DART) ion-source coupled with a time-of-flight mass spectrometer (TOF MS) and a desorption electrospray ionization (DESI) source coupled with a linear ion trap tandem MS (LIT MS(n)), permitted a direct screen of the occurrence of target fungicides in treated grains in less than 1 min. For quantification purpose by DART-TOF MS, an ethyl acetate extract had to be prepared. With the use of a prochloraz as an internal standard, the performance characteristics obtained by repeated analyses of extract, spiked at 50 microg kg(-1) with six strobilurins (azoxystrobin, picoxystrobin, dimoxystrobin, kresoxim-methyl, pyraclostrobin, and trifloxystrobin), were in the following range: recoveries 78-92%, repeatability (RSD) 8-15%, linearity (R(2)) 0.9900-0.9978. The analysis of wheat with incurred strobilurin residues demonstrated good trueness of data generated by the DART-TOF MS method; the results were in a good agreement with those obtained by the conventional approach, i.e., by the QuEChERS sample handling procedure followed by identification/quantification employing high-performance liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). Tandem mass spectrometry using DESI-LIT MS(n) provided a sufficient number of product ions for confirmation of the identity of azoxystrobin and pyraclostrobin in incurred wheat samples. PMID:19007189

Schurek, Jakub; Vaclavik, Lukas; Hooijerink, H Dick; Lacina, Ondrej; Poustka, Jan; Sharman, Matthew; Caldow, Marianne; Nielen, Michel W F; Hajslova, Jana

2008-12-15

233

Nontarget screening of organic contaminants in marine salts by gas chromatography coupled to high-resolution time-of-flight mass spectrometry  

Microsoft Academic Search

Gas chromatography coupled to time-of-flight mass spectrometry (GC–TOF MS) has been applied to characterize the organic pollution pattern of marine salt samples collected in saltworks from the Spanish Mediterranean coast. After dissolving the samples in water, a solid-phase extraction was applied reaching with a 250-preconcentration factor. The screening methodology allowed the detection of sample components without any kind of pre-selection

Roque Serrano; Jaime Nácher-Mestre; Tania Portolés; Francisco Amat; Félix Hernández

2011-01-01

234

Small protein biomarkers of culture in Bacillus spores detected using capillary liquid chromatography coupled with matrix assisted laser desorption\\/ionization mass spectrometry  

Microsoft Academic Search

Capillary liquid chromatography (cLC) coupled with matrix-assisted laser desorption\\/ionization (MALDI) time-of-flight mass spectrometry (TOF-MS) was used to compare small proteins and peptides extracted from Bacillus subtilis spores grown on four different media. A single, efficient protein separation, compatible with MALDI–MS analysis, was employed to reduce competitive ionization between proteins, and thus interrogate more proteins than possible using direct MALDI–MS. The

David S. Wunschel; Jon H. Wahl; Alan R. Willse; Nancy B. Valentine; Karen L. Wahl

2006-01-01

235

Application of Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry for Identification of the Fastidious Pediatric Pathogens Aggregatibacter, Eikenella, Haemophilus, and Kingella  

PubMed Central

The accuracy of matrix-assisted laser desorption–ionization time of flight mass spectrometry (MALDI-TOF MS) in the identification of Haemophilus, Aggregatibacter, Cardiobacterium, Eikenella, and Kingella (HACEK) species was compared to that of phenotypic methods (Remel RapID and Vitek 2). Overall, Vitek MS correctly identified more isolates, incorrectly identified fewer isolates, and failed to identify fewer isolates than both phenotypic methods.

Powell, Eleanor A.; Blecker-Shelly, Deborah; Montgomery, Sandra

2013-01-01

236

Application of delayed extraction matrix-assisted laser desorption ionization time-of-flight mass spectrometry for analysis of sphingolipids in tissues from sphingolipidosis patients  

Microsoft Academic Search

Sphingolipidosis is due to defects in enzymes involved in hydrolysis of sphingolipids. We analyzed sphingolipids in tissues from patients with sphingolipidosis, including Farber disease (FD, acid ceramidase deficiency), Gaucher disease (GD), Niemann–Pick disease type C (NPDC), and GM1-gangliosidosis (GM1G), using delayed extraction matrix-assisted laser desorption ionization time-of-flight mass spectrometry (DE MALDI–TOF–MS). Crude lipids were extracted from about 100 mg wet

Takehisa Fujiwaki; Seiji Yamaguchi; Kazuko Sukegawa; Tamotsu Taketomi

1999-01-01

237

Application of delayed extraction matrix-assisted laser desorption ionization time-of-flight mass spectrometry for analysis of sphingolipids in cultured skin fibroblasts from sphingolipidosis patients  

Microsoft Academic Search

Sphingolipidoses are caused by defects of enzymes involved in the hydrolysis of sphingolipids. Using delayed extraction matrix-assisted laser desorption ionization time-of-flight mass spectrometry (DE MALDI-TOF-MS), we analyzed sphingolipids in cultured skin fibroblasts from patients with sphingolipidoses, including: (a) Farber disease (FD, acid ceramidase deficiency); (b) Gaucher disease (GD); (c) Niemann-Pick disease type C (NPDC); and (d) GM1-gangliosidosis (GM1G). Crude lipids

Takehisa Fujiwaki; Seiji Yamaguchi; Kazuko Sukegawa; Tamotsu Taketomi

2002-01-01

238

Evaluation of the bruker biotyper matrix-assisted laser desorption ionization-time of flight mass spectrometry system for identification of blood isolates of acinetobacter species.  

PubMed

Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) (Bruker Biotyper) was able to accurately identify 98.6% (142/144) of Acinetobacter baumannii isolates, 72.4% (63/87) of A. nosocomialis isolates, and 97.6% (41/42) of A. pittii isolates. All Acinetobacter junii, A. ursingii, A. johnsonii, and A. radioresistens isolates (n = 28) could also be identified correctly by Bruker Biotyper. PMID:24899038

Hsueh, Po-Ren; Kuo, Lu-Cheng; Chang, Tsung-Chain; Lee, Tai-Fen; Teng, Shih-Hua; Chuang, Yu-Chung; Teng, Lee-Jene; Sheng, Wang-Huei

2014-08-01

239

Optimization and evaluation of surface-enhanced laser-desorption\\/ionization time-of-flight mass spectrometry for protein profiling of cerebrospinal fluid  

Microsoft Academic Search

Cerebrospinal fluid (CSF) potentially carries an archive of peptides and small proteins relevant to pathological processes in the central nervous system (CNS) and surrounding brain tissue. Proteomics is especially well suited for the discovery of biomarkers of diagnostic potential in CSF for early diagnosis and discrimination of several neurodegenerative diseases. ProteinChip surface-enhanced laser-desorption\\/ionization time-of-flight mass spectrometry (SELDI-TOF-MS) is one such

Nelson Guerreiro; Baltazar Gomez-Mancilla; Stéphane Charmont

2006-01-01

240

Plasma pharmacokinetics, tissue distribution and excretion study of 6-gingerol in rat by liquid chromatography–electrospray ionization time-of-flight mass spectrometry  

Microsoft Academic Search

A rapid resolution liquid chromatography coupled with electrospray ionization (ESI) time-of-flight mass spectrometry method was developed and validated for quantitative analysis of 6-gingerol in plasma and various tissues. Liquid–liquid extraction was employed as sample preparation technique. Biological samples were separated on an Agilent Zorbax StableBond-C18 column (4.6mm×50mm, 1.8?m) and detected by TOF\\/MS with electrospray ionization (ESI) interface in positive ion

Wei Wang; Chang-Yin Li; Xiao-Dong Wen; Ping Li; Lian-Wen Qi

2009-01-01

241

Analysis of the lipid composition of human and boar spermatozoa by MALDI-TOF mass spectrometry, thin layer chromatography and 31P NMR spectroscopy  

Microsoft Academic Search

Alterations in the phospholipid (PL) composition of spermatozoal membranes occur during the fertilization process. Furthermore, membrane lipid composition is of high interest with respect to cryopreservation. The PL and fatty acid compositions of human and boar spermatozoa are compared by using matrix-assisted laser desorption and ionization time-of-flight mass spectrometry (MALDI-TOF MS) in combination with thin-layer chromatography and 31P NMR spectroscopy.

Jacqueline Leßig; Claudia Gey; Rosemarie Süß; Jürgen Schiller; Hans-Jürgen Glander; Jürgen Arnhold

2004-01-01

242

An in situ silver cationization method for hydrocarbon mass spectrometry.  

PubMed

We have developed a novel cationization method for the analysis of long-chain hydrocarbons via UV laser desorption mass spectrometry. In this technique we electrospray a thin coating of AgNO3 over a sample and perform UV laser desorption to produce Ag+ cationization of sample molecules. Use of this technique in our microscope/TOF-MS allows us to determine the spatial distribution of the species we detect in the sample. We demonstrate 8-mu spatial resolution, and submicron resolution is possible in principle. In mixed samples containing aromatic and aliphatic compounds, the aromatic compounds ionize directly and do not form adducts, and thus give single peaks as opposed to doublets from silver cations. This enables distinction between aromatic and aliphatic compounds that are in the same sample. PMID:15792711

Grace, Louis I; Abo-Riziq, Ali; deVries, Mattanjah S

2005-04-01

243

In cleanroom, sub-ppb real-time monitoring of volatile organic compounds using proton-transfer reaction/time of flight/mass spectrometry  

NASA Astrophysics Data System (ADS)

Refractory compounds such as Trimethylsilanol (TMS) and other organic compounds such as propylene glycol methyl ether acetate (PGMEA) used in the photolithography area of microelectronic cleanrooms have irreversible dramatic impact on optical lenses used on photolithography tools. There is a need for real-time, continuous measurements of organic contaminants in representative cleanroom environment especially in lithography zone. Such information is essential to properly evaluate the impact of organic contamination on optical lenses. In this study, a Proton-Transfer Reaction-Time-of-Flight Mass spectrometer (PTR-TOF-MS) was applied for real-time and continuous monitoring of fugitive organic contamination induced by the fabrication process. Three types of measurements were carried out using the PTR-TOF-MS in order to detect the volatile organic compounds (VOCs) next to the tools in the photolithography area and at the upstream and downstream of chemical filters used to purge the air in the cleanroom environment. A validation and verification of the results obtained with PTR-TOF-MS was performed by comparing these results with those obtained with an off-line technique that is Automated Thermal Desorber - Gas Chromatography - Mass Spectrometry (ATD-GC-MS) used as a reference analytical method. The emerged results from the PTR-TOF-MS analysis exhibited the temporal variation of the VOCs levels in the cleanroom environment during the fabrication process. While comparing the results emerging from the two techniques, a good agreement was found between the results obtained with PTR-TOF-MS and those obtained with ATD-GC-MS for the PGMEA, toluene and xylene. Regarding TMS, a significant difference was observed ascribed to the technical performance of both instruments.

Hayeck, Nathalie; Maillot, Philippe; Vitrani, Thomas; Pic, Nicolas; Wortham, Henri; Gligorovski, Sasho; Temime-Roussel, Brice; Mizzi, Aurélie; Poulet, Irène

2014-04-01

244

Evaluation of inter-day and inter-individual variability of tear peptide/protein profiles by MALDI-TOF MS analyses  

PubMed Central

Purpose To characterize the tear film peptidome and low molecular weight protein profiles of healthy control individuals, and to evaluate changes due to day-to-day and individual variation and tear collection methods, by using solid phase extraction coupled to matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) profiling. Methods The tear protein profiles of six healthy volunteers were analyzed over seven days and inter-day and inter-individual variability was evaluated. The bilaterality of tear film and the effect of tear collection methods on protein profiles were also analyzed in some of these patients. MALDI-TOF MS analyses were performed on tear samples purified by using a solid phase extraction (SPE) method based on C18 functionalized magnetic beads for peptide and low molecular weight protein enrichment, focusing spectra acquisition on the 1 to 20 kDa range. Spectra were analyzed using principal component analysis (PCA) with MultiExperiment Viewer (TMeV) software. Volunteers were examined in terms of tear production status (Schirmer I test), clinical assessment of palpebral lids and meibomian glands, and a subjective OSD questionnaire before tear collection by a glass micro-capillary. Results Analysis of peptides and proteins in the 1–20 kDa range showed no significant inter-day differences in tear samples collected from six healthy individuals during seven days of monitoring, but revealed subtle intrinsic inter-individual differences. Profile analyses of tears collected from the right and left eyes confirmed tear bilaterality in four healthy patients. The addition of physiologic serum for tear sample collection did not affect the peptide and small protein profiles with respect to the number of resolved peaks, but it did reduce the signal intensity of the peaks, and increased variability. Magnetic beads were found to be a suitable method for tear film purification for the profiling study. Conclusions No significant variability in tear peptide and protein profiles below 20 kDa was found in healthy controls over a seven day period, nor in right versus left eye profiles from the same individual. Subtle inter-individual differences can be observed upon tear profiling analysis and confirm intrinsic variability between control subjects. Addition of physiologic serum for tear collection affects the proteome and peptidome in terms of peak intensities, but not in the composition of the profiles themselves. This work shows that MALDI-TOF MS coupled with C18 magnetic beads is an effective and reproducible methodology for tear profiling studies in the clinical monitoring of patients.

Gonzalez, Nerea; Iloro, Ibon; Duran, Juan A.; Elortza, Felix

2012-01-01

245

BioSunMS: a plug-in-based software for the management of patients information and the analysis of peptide profiles from mass spectrometry  

PubMed Central

Background With wide applications of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF MS), statistical comparison of serum peptide profiles and management of patients information play an important role in clinical studies, such as early diagnosis, personalized medicine and biomarker discovery. However, current available software tools mainly focused on data analysis rather than providing a flexible platform for both the management of patients information and mass spectrometry (MS) data analysis. Results Here we presented a plug-in-based software, BioSunMS, for both the management of patients information and serum peptide profiles-based statistical analysis. By integrating all functions into a user-friendly desktop application, BioSunMS provided a comprehensive solution for clinical researchers without any knowledge in programming, as well as a plug-in architecture platform with the possibility for developers to add or modify functions without need to recompile the entire application. Conclusion BioSunMS provides a plug-in-based solution for managing, analyzing, and sharing high volumes of MALDI-TOF or SELDI-TOF MS data. The software is freely distributed under GNU General Public License (GPL) and can be downloaded from http://sourceforge.net/projects/biosunms/.

2009-01-01

246

The value of MALDI-TOF MS for the identification of clinically relevant anaerobic bacteria in routine laboratories.  

PubMed

Between 2010 and 2011, 283 clinically relevant non-duplicate anaerobic isolates were analysed by MALDI-TOF MS and the results were compared with conventional identification. Immediately after isolation, an ethanol precipitation was carried out on isolated colonies and the stabilized samples were anonymized and sent to the laboratory of Bruker Daltonik, Bremen, Germany, where the identification was done using the standard protocol for micro-organism identification on a Microflex LT mass spectrometer equipped with the MALDI Biotyper 3.0 software. Of 283 isolates, 218 (77?%) were identified at species level [log(score) ?2.0], 31 isolates (10.95?%) were identified at genus level [log(score) 1.7-2.0] and 34 (12?%) gave non-reliable identification [log(score) <1.7]. Out of the 31 isolates with log(score) 1.7-2.0, in the case of 24 isolates the species name given by the MALDI Biotyper was accepted if it was the same as for the classical identification. Of 218 isolates identified at species level, 40 results were discordant with phenotypic identification, and of the 31 isolates identified at genus level according to the manufacturer's score cut-off, four gave results discordant with the phenotypic method. For the 44 discordant results, 16S rRNA gene sequencing confirmed MALDI-TOF MS identification in 41 cases, leaving three isolates (0.7?%) that had been misidentified by MALDI-TOF MS. PMID:22700545

Nagy, Elisabeth; Becker, Simone; Kostrzewa, Markus; Barta, Noémi; Urbán, Edit

2012-10-01

247

Performance of matrix-assisted laser desorption-time of flight mass spectrometry for identification of clinical yeast isolates.  

PubMed

Accurate and fast yeast identification is important when treating patients with invasive fungal disease as susceptibility to antifungal agents is highly species related. Matrix-assisted laser desorption-time of flight mass spectrometry (MALDI-TOF-MS) provides a powerful tool with a clear potential to improve current diagnostic practice. Two MALDI-TOF-MS-systems (BioTyper/Bruker and Saramis/AXIMA) were evaluated using: (i) A collection of 102 archived, well characterised yeast isolates representing 14 different species and (ii) Prospectively collected isolates obtained from clinical samples at two participating laboratories. Of the 102 archived isolates, 81 (79%) and 92 (90%) were correctly identified by Saramis/AXIMA and BioTyper/Bruker respectively. Saramis/AXIMA was unable to separate Candida albicans, C. africana and C. dubliniensis in 13 of 32 isolates. After manual interpretation of the mass spectra output, all 13 isolates were correctly identified, resulting in an overall identification performance of 92%. No misidentifications occurred with the two systems. Of the routine isolates one laboratory identified 99/99 (100%) and 90/99 (91%) to species level by Saramis/Axima and conventional identification, respectively, whereas the other laboratory identified 83/98 (85%) to species level by both BioTyper/Bruker and conventional identification. Both MALDI-TOF-MS systems are fast, have built-in databases that cover the majority of clinically relevant Candida species, and have an accuracy that outperforms our conventional identification systems. PMID:22924975

Rosenvinge, Flemming S; Dzajic, Esad; Knudsen, Elisa; Malig, Sanne; Andersen, Line B; Løvig, Annette; Arendrup, Maiken C; Jensen, Thøger G; Gahrn-Hansen, Bente; Kemp, Michael

2013-05-01

248

Comparison of MALDI-TOF MS and VITEK 2 system for laboratory diagnosis of Granulicatella and Abiotrophia species causing invasive infections.  

PubMed

Granulicatella and Abiotrophia spp. were known as nutritionally variant streptococci (NVS). Such strains have caused major diagnostic difficulties due to fastidious culturing and unspecific colony morphology. The present study is aimed at comparing the performance of laboratory available diagnostic methods for NVS isolates and determining the antimicrobial susceptibility of these isolates. Fourteen clinical invasive isolates, consisting of 10 Granulicatella adiacens, 1 Granulicatella elegans, and 3 Abiotrophia defectiva were in parallel analyzed by 2 matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) systems, i.e., Bruker MS and Vitek MS, as well as Vitek 2 for the species determination. 16S rRNA gene sequencing was applied as a reference method. The Vitek MS gave correct identification for all 14 isolates. The Bruker MS could correctly identify 8/10 G. adiacens, 0/1 G. elegans, and 3/3 A. defectiva isolates at the first analysis occasion, and all 14 isolates became identifiable after repeated tests. The Vitek 2 system could identify 6/10 G. adiacens, 1/1 G. elegans, and 2/3 A. defectiva isolates at the species level. Antimicrobial susceptibilities of 11 antibiotics were determined by Etest. Resistance against ciprofloxacin, ceftriaxone, rifampicin, and tetracycline were observed in 4, 10, 4, and 1 isolates, respectively. In conclusion, MALDI-TOF MS is a useful tool for the rapid diagnosis of NVS. Phenotypic testing by Vitek 2 is only partially effective for the accurate identification of such strains. The emergence of resistant NVS isolates indicates the necessity of monitoring antimicrobial susceptibilities of such uncommon pathogens. PMID:24034902

Ratcliffe, Paul; Fang, Hong; Thidholm, Ellinor; Boräng, Stina; Westling, Katarina; Özenci, Volkan

2013-11-01

249

High-Throughput Profiling of Protein N-Glycosylation by MALDI-TOF-MS Employing Linkage-Specific Sialic Acid Esterification.  

PubMed

Protein glycosylation is an important post-translational modification associated, among others, with diseases and the efficacy of biopharmaceuticals. Matrix-assisted laser desorption/ionization (MALDI) time-of-fight (TOF) mass spectrometry (MS) can be performed to study glycosylation in a high-throughput manner, but is hampered by the instability and ionization bias experienced by sialylated glycan species. Stabilization and neutralization of these sialic acids can be achieved by permethylation or by specific carboxyl group derivatization with the possibility of discrimination between ?2,3- and ?2,6-linked sialic acids. However, these methods typically require relatively pure glycan samples, show sensitivity to side reactions, and need harsh conditions or long reaction times. We established a rapid, robust and linkage-specific high-throughput method for sialic acid stabilization and MALDI-TOF-MS analysis, to allow direct modification of impure glycan-containing mixtures such as PNGase F-released human plasma N-glycome. Using a combination of carboxylic acid activators in ethanol achieved near-complete ethyl esterification of ?2,6-linked sialic acids and lactonization of ?2,3-linked variants, in short time using mild conditions. Glycans were recovered by hydrophilic interaction liquid chromatography solid phase extraction and analyzed by MALDI-TOF-MS in reflectron positive mode with 2,5-dihydroxybenzoic acid as the matrix substance. Analysis of the human plasma N-glycome allowed high-throughput detection and relative quantitation of more than 100 distinct N-glycan compositions with varying sialic acid linkages. PMID:24831253

Reiding, Karli R; Blank, Dennis; Kuijper, Dennis M; Deelder, André M; Wuhrer, Manfred

2014-06-17

250

Multi-element analysis of milk by ICP-oa-TOF-MS after precipitation of calcium and proteins by oxalic and nitric acid.  

PubMed

In this work a simple technique employing oxalic and nitric acid to cow's milk samples prior to analysis by inductively coupled plasma orthogonal acceleration time-of-flight mass spectrometry (ICP-oa-TOF-MS) was introduced. After the precipitation of calcium and proteins via oxalic and nitric acid, respectively, the resulting liquid phase was aspirated with a concentric glass nebulizer for ICP-TOF-MS determination of trace elements. Precipitation of proteins is essential for better separation of solid and liquid phase of modified samples. Separation of calcium as a precipitated non-soluble oxalate enables the elimination of spectral interferences originating from different calcium containing species like (40)Ca(35)Cl(+), (40)Ca(37)Cl(+), (43)Ca(16)O(+), (40)Ca(18)O(+), (44)Ca(16)O(+), (43)Ca(16)O(1)H(+) onto the determination of As, Se, Co and Ni whose assay is more difficult when using conventional quadrupole instruments. High detection capability is further an advantage as the approach enables the analysis without dilution. The methodology may serve, in addition, for a fast and sensitive determination of some other elements. After that, direct, reliable and simultaneous determination of 16 elements (Li, Be, B, V, Cr, Mn, Ni, Co, Ga, As, Se, Mo, Sn, Sb, Cs, Tl) at trace and ultra-trace levels in milk can be performed under optimum instrumental conditions and by using Rh as an internal standard. Accuracy and precision was assessed by measuring NCS ZC73015 milk powder control standard, yielding results in agreement with certified values and RSD <10%. The accuracy was also checked by comparison of the results of the proposed method with those found by a method based on a microwave-assisted digestion of real samples. PMID:23598096

Husáková, Lenka; Urbanová, Iva; Šrámková, Jitka; Kone?ná, Michaela; Bohuslavová, Jana

2013-03-15

251

Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry for Fast and Reliable Identification of Clinical Yeast Isolates?  

PubMed Central

The clinical impact of severe infections with yeasts and yeast-like fungi has increased, especially in immunocompromised hosts. In recent years, new antifungal agents with different and partially species-specific activity patterns have become available. Therefore, rapid and reliable species identification is essential for antifungal treatment; however, conventional biochemical methods are time-consuming and require considerable expertise. We evaluated matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) for the rapid routine identification of clinical yeast isolates. A total of 18 type collection strains and 267 recent clinical isolates of Candida (n = 250), Cryptococcus, Saccharomyces, Trichosporon, Geotrichum, Pichia, and Blastoschizomyces spp. were identified by MALDI-TOF MS. The results were compared with those obtained by conventional phenotyping and biochemical tests, including the API ID 32C system (bioMérieux, Nürtingen, Germany). Starting with cells from single colonies, accurate species identification by MALDI-TOF MS was achieved for 247 of the clinical isolates (92.5%). The remaining 20 isolates required complementation of the reference database with spectra for the appropriate reference strains which were obtained from type culture collections or identified by 26S rRNA gene sequencing. The absence of a suitable reference strain from the MALDI-TOF MS database was clearly indicated by log(score) values too low for the respective clinical isolates; i.e., no false-positive identifications occurred. After complementation of the database, all isolates were unambiguously identified. The established API ID 32C biochemical diagnostic system identified 244 isolates in the first round. Overall, MALDI-TOF MS proved a most rapid and reliable tool for the identification of yeasts and yeast-like fungi, with the method providing a combination of the lowest expenditure of consumables, easy interpretation of results, and a fast turnaround time.

Marklein, G.; Josten, M.; Klanke, U.; Muller, E.; Horre, R.; Maier, T.; Wenzel, T.; Kostrzewa, M.; Bierbaum, G.; Hoerauf, A.; Sahl, H.-G.

2009-01-01

252

Species identification of Aspergillus, Fusarium and Mucorales with direct surface analysis by matrix-assisted laser desorption ionization time-of-flight mass spectrometry.  

PubMed

Accurate species discrimination of filamentous fungi is essential, because some species have specific antifungal susceptibility patterns, and misidentification may result in inappropriate therapy. We evaluated matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) for species identification through direct surface analysis of the fungal culture. By use of culture collection strains representing 55 species of Aspergillus, Fusarium and Mucorales, a reference database was established for MALDI-TOF MS-based species identification according to the manufacturer's recommendations for microflex measurements and MALDI BioTyper 2.0 software. The profiles of young and mature colonies were analysed for each of the reference strains, and species-specific spectral fingerprints were obtained. To evaluate the database, 103 blind-coded fungal isolates collected in the routine clinical microbiology laboratory were tested. As a reference method for species designation, multilocus sequencing was used. Eighty-five isolates were unequivocally identified to the species level (?99% sequence similarity); 18 isolates producing ambiguous results at this threshold were initially rated as identified to the genus level only. Further molecular analysis definitively assigned these isolates to the species Aspergillus oryzae (17 isolates) and Aspergillus flavus (one isolate), concordant with the MALDI-TOF MS results. Excluding nine isolates that belong to the fungal species not included in our reference database, 91 (96.8%) of 94 isolates were identified by MALDI-TOF MS to the species level, in agreement with the results of the reference method; three isolates were identified to the genus level. In conclusion, MALDI-TOF MS is suitable for the routine identification of filamentous fungi in a medical microbiology laboratory. PMID:21883662

De Carolis, E; Posteraro, B; Lass-Flörl, C; Vella, A; Florio, A R; Torelli, R; Girmenia, C; Colozza, C; Tortorano, A M; Sanguinetti, M; Fadda, G

2012-05-01

253

A MALDI-TOF MS study of oligomeric poly(m-phenyleneisophthalamide).  

PubMed

MALDI-TOF MS was used to study the end-group distribution of a series of poly(m-phenyleneisophthalamide) oligomers which were synthesized using various mole percent ratios of diamine to diacid chloride (90:10, 80:20, 70:30, 60:40, 50:50, 40:60, 30:70, 20:80, and 10:90) to clarify results obtained in previous work published in this journal. Oligomers synthesized with excess diamine or excess diacid chloride were found to contain abundances of amine or carboxylate end groups, respectively, as expected. Oligomers synthesized with equal molar ratios of reactants produced cyclic species which were also found in a previous publication as an oligomer in commercially produced, high molecular mass Nomex. PMID:15679344

Gies, Anthony P; Nonidez, William K; Ellison, Sparkle T; Ji, Haining; Mays, Jimmy W

2005-02-01

254

Identification of Plesiomonas spp.: serological and MALDI-TOF MS methods.  

PubMed

Biochemical and serological profiles of isolates of Plesiomonas shigelloides were assayed using standard procedures in isolates from various clinical samples. Seventy-four isolates, including P. shigelloides type strain, were further characterized by MALDI-TOF MS using 3-methoxy-4-hydroxycinnamic acid as matrix. Multiple ions in the 3- to 12-kDa mass range were found in the spectra of each strain, from which the "species-identifying" unique biomarker ions were identified. After creating the species-specific patterns, a spectral database was generated for reliable, rapid, reproducible and accurate identification of Plesiomonas strains. The classical strain description (biochemical and serological) was thus complemented with the metabolic (proteomic) characterization. PMID:21253918

Kolínská, R; D?evínek, M; Aldová, E; Zemli?ková, H

2010-11-01

255

False results caused by solvent impurity in tetrahydrofuran for MALDI TOF MS analysis of amines.  

PubMed

Tetrahydrofuran (THF) is one of the most frequently used solvents in the MALDI TOF MS analysis of synthetic compounds. However, it should be used with caution because a trace amount of 4-hydroxybutanal (HBA) might be generated and accumulated in THF during storage. Since only a tiny amount of analytes is required in MALDI MS measurements, a trace amount of HBA might have a significant effect on the MS results. It was found that HBA will quickly react with primary and secondary amino compounds, leading to false results about the sample composition with an extra series of ions with additional mass of 70 Da in between. The formation of HBA can be inhibited by butylated hydroxytoluene (BHT) antioxidant. Therefore, when THF is required as the solvent for sample preparation, it is strongly recommended to use a BHT-stabilized one, at least for the analysis of compounds with amino groups. PMID:24222486

Lou, Xianwen; Leenders, Christianus M A; van Onzen, Arthur H A M; Bovee, Ralf A A; van Dongen, Joost L J; Vekemans, Jef A J M; Meijer, E W

2014-02-01

256

Identification of beer-spoilage bacteria using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.  

PubMed

Applicability of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for identification of beer-spoilage bacteria was examined. To achieve this, an extensive identification database was constructed comprising more than 4200 mass spectra, including biological and technical replicates derived from 273 acetic acid bacteria (AAB) and lactic acid bacteria (LAB), covering a total of 52 species, grown on at least three growth media. Sequence analysis of protein coding genes was used to verify aberrant MALDI-TOF MS identification results and confirmed the earlier misidentification of 34 AAB and LAB strains. In total, 348 isolates were collected from culture media inoculated with 14 spoiled beer and brewery samples. Peak-based numerical analysis of MALDI-TOF MS spectra allowed a straightforward species identification of 327 (94.0%) isolates. The remaining isolates clustered separately and were assigned through sequence analysis of protein coding genes either to species not known as beer-spoilage bacteria, and thus not present in the database, or to novel AAB species. An alternative, classifier-based approach for the identification of spoilage bacteria was evaluated by combining the identification results obtained through peak-based cluster analysis and sequence analysis of protein coding genes as a standard. In total, 263 out of 348 isolates (75.6%) were correctly identified at species level and 24 isolates (6.9%) were misidentified. In addition, the identification results of 50 isolates (14.4%) were considered unreliable, and 11 isolates (3.2%) could not be identified. The present study demonstrated that MALDI-TOF MS is well-suited for the rapid, high-throughput and accurate identification of bacteria isolated from spoiled beer and brewery samples, which makes the technique appropriate for routine microbial quality control in the brewing industry. PMID:24929682

Wieme, Anneleen D; Spitaels, Freek; Aerts, Maarten; De Bruyne, Katrien; Van Landschoot, Anita; Vandamme, Peter

2014-08-18

257

Dual Polarity Accurate Mass Calibration for ESI and MALDI Mass Spectrometry Using Maltooligosaccharides  

PubMed Central

In view of the fact that memory effects associated with instrument calibration hinder the use of many m/z and tuning standards, identification of robust, comprehensive, inexpensive, and memory-free calibration standards are of particular interest to the mass spectrometry community. Glucose and its isomers are known to have a residue mass of 162.05282 Da; therefore, both linear and branched forms of poly-hexose oligosaccharides possess well defined masses making them ideal candidates for mass calibration. Using a wide range of maltooligosaccharides (MOS) derived from commercially available beers, ions with m/z ratios from ~500 Da to 2500 Da or more have been observed using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) and time of flight mass spectrometry (TOF-MS). The mixtures of MOS were further characterized using infrared multiphoton dissociation (IRMPD) and nano-liquid chromatography/mass spectrometry (nano-LC/MS). In addition to providing well defined series of positive and negative calibrant ions using either ESI or MALDI, the MOS are not encumbered by memory effects and are thus well suited mass calibration and instrument tuning standards for carbohydrate analysis.

Clowers, Brian H.; Dodds, Eric D.; Seipert, Richard R.; Lebrilla, Carlito B.

2009-01-01

258

Analysis of new synthetic drugs by ion mobility time-of-flight mass spectrometry.  

PubMed

Characteristic ion mobility mass spectrometry data, reduced mobility, and limits of detection (signal-to-noise ratio = 3) were determined for six synthetic drugs and cocaine by ion mobility time-of-flight mass spectrometry (IM-TOF-MS) with electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI). The studied synthetic illicit drugs recently appeared on the recreational drug market as designer drugs and were methylone, 4-MEC (4'-methylethcathinone), 3,4-MDPV (3,4-methylenedioxypyrovalerone), JWH-210 [4-ethylnaphthalen-1-yl-(1-pentylindol-3-yl)methanone], JWH-250 [2-(2-methoxyphenyl)-1-(1-pentyl-1H-indol-3-yl)ethanone], and JWH-203 [1-pentyl-3-(2'-chlorophenylacetyl) indole]. Absolute reduced mobilities in nitrogen were 1.35, 1.28, 1.41, 1.30, 1.18, 0.98, 1.09, and 1.07 cm2V(-1)s(-1), for methylone [M-H]+, methylone [M+H]+, 4-MEC [M-H]+, 4-MEC [M+H]+, 3,4-MDPV [M+H]+, JWH-210 [M+H]+, JWH-250 [M+H]+, and JWH-203 [M+H]+, respectively. Selected illicit drugs are easily identified by IM-TOF-MS during a 100s analysis. Relative Limits of detection ranged from 4 to 400 nM are demonstrated for these compounds. Such relative limits of detection correspond to 14 pg to 2 ng absolute limits of detection. Better detection limits are obtained in APCI mode for all the illicit drugs except cocaine. ESI mode was found to be preferable for the IM-TOF-MS detection of cocaine at trace levels. A single sample analysis is completed in an order of magnitude less time than that for conventional liquid chromatography/mass spectrometry approach. The application allows one to consider IM-TOF-MS as a good candidate for a method to determine quickly the recently surfaced designer drugs marketed on the internet as "bath salts," "spice," and "herbal blends". PMID:24895779

Sysoev, Alexey A; Poteshin, Sergey S; Chernyshev, Denis M; Karpov, Alexander V; Tuzkov, Yuriy B; Kyzmin, Vyacheslav V; Sysoev, Alexander A

2014-01-01

259

A novel method to differentiate bovine and porcine gelatins in food products: nanoUPLC-ESI-Q-TOF-MS(E) based data independent acquisition technique to detect marker peptides in gelatin.  

PubMed

We presented a novel nanoUPLC-MS(E) workflow method that has potential to identify origin of gelatin in some dairy products; yoghurt, cheese and ice cream. In this study, the method was performed in two steps. In the first step, gelatin was extracted from these products before the MS-sample preparation. In the second step, tryptic gelatin peptides were separated and analyzed with ultra-performance liquid chromatography and electrospray ionization quadrupole time-of-flight mass spectrometry (nanoUPLC-ESI-q-TOF-MS(E)). The novelty of this setup was that it functioned in a data independent acquisition mode and that alternate low and elevated collision energy was applied to acquire precursor and product ion information. This enabled accurate mass acquisition on the peptide level to identify the gelatin peptides. The marker peptides specific for porcine and bovine could be successfully detected in the gelatin added to the dairy products analyzed, revealing that the detection of marker peptides in the digested gelatin samples using nanoUPLC-ESI-q-TOF-MS(E) could be an effective method to differentiate porcine and bovine gelatin in the dairy products. PMID:23870980

Yilmaz, Mustafa Tahsin; Kesmen, Zulal; Baykal, Betul; Sagdic, Osman; Kulen, Oktay; Kacar, Omer; Yetim, Hasan; Baykal, Ahmet Tarik

2013-12-01

260

Multiresidue pesticide analysis by capillary gas chromatography-mass spectrometry.  

PubMed

A multiresidue pesticide method using a modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) procedure and capillary gas chromatography-mass spectrometry (GC-MS) is described for the determination of 166 organochlorine, organophosphorus, and pyrethroid pesticides, metabolites, and isomers in spinach. The pesticides from spinach were extracted using acetonitrile saturated with magnesium sulfate and sodium chloride, followed by solid-phase dispersive cleanup using primary-secondary amine and graphitized carbon black sorbents and toluene. Analysis is performed using different GC-MS techniques emphasizing the benefits of non-targeted acquisition and targeted screening procedures. Non-targeted data acquisition of pesticides in the spinach was demonstrated using GC coupled to a single quadrupole mass spectrometery (GC-MS) in full scan mode or multidimensional GC-time-of-flight mass spectrometery (GC ?× ?GC-TOF/MS), along with deconvolution software and libraries. Targeted screening was achieved using GC-single quadrupole mass spectrometry in selective ion monitoring (GC-MS/SIM) mode or -tandem mass spectrometry (GC-MS/MS) in multiple reaction monitoring mode. The development of these techniques demonstrates the powerful use of GC-MS for the screening, identification, and quantitation of pesticide residues in foods. PMID:21643907

Wong, Jon W; Zhang, Kai; Hayward, Douglas G; Kai-Meng, Chin

2011-01-01

261

Simple and fast method for recognition of reducing and nonreducing neutral carbohydrates by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.  

PubMed

Negative-ion mode matrix-assisted laser desorption/ionization (MALDI) time-of-flight mass spectrometry (TOF-MS) was used for the characterization of storage, neutral oligosaccharides extracted from Jerusalem artichoke, red onion, and wheat. The oligosaccharides from the real samples were analyzed with 2,4,6-trihydroxyacetophenone as the most convenient matrix that was selected in advance with the standard carbohydrate samples (inulin and maltooligosaccharides). The oligosaccharides from Jerusalem artichoke and red onion (similarly as inulin) produced [M - H](-) peaks as the main distribution, which reflects their nonreducing composition. On the contrary, the cross-ring fragmentations [M - H - 120](-) formed the main distribution in the mass spectra of hydrolyzed wheat starch similarly to reducing maltooligosaccharides and dextrans. The negative-ion mode MALDI-TOF MS is capable of recognizing reducing and nonreducing oligosaccharides. Such a simple differentiation of malto or inulin type of oligosaccharides is not possible in the positive-ion mode. PMID:16819921

Lastovicková, Markéta; Chmelík, Josef

2006-07-12

262

What is Mass Spectrometry?  

NSDL National Science Digital Library

This site from the American Society for Mass Spectrometry includes information about what mass spectometry is and how it is used. It has many useful figures and references to other materials. The material answers questions such as "What is mass spectrometry and what can it do for you?"

Chiu, Chia M.

2012-09-21

263

Initializing a digital chromatography data archive for tropospheric air samples on Taunus Observatory Frankfurt by GC-TOF-MS  

NASA Astrophysics Data System (ADS)

The inception of a digital air archive for halogenated hydrocarbons will be presented. This archive is based on weekly samples taken at the Taunus Observatory on "Kleiner Feldberg" near Frankfurt/ Main, i.e. a very central position in Germany. The station is characterized by a mixture of clean air, moderately polluted air and occasional influence from the nearby city of Frankfurt. Regular meteorological and air quality data are available from the German Weather service (DWD) and the regional air quality monitoring (Hessiche Landesanstalt für Umwelt und Geologie, HLUG). Two air samples are collected in parallel in 2 l stainless steel flasks using a metal bellows pump. The air samples are analysed in the laboratory by gas chromatography coupled with Time of Flight Mass Spectrometry (GC TOF MS) and Quadrupole Mass Spectrometry (GC QUAD MS) for halogenated trace gases. Analysis is carried out no later than a month after sampling. Our current target species which will be measured by both mass spectrometers contain a wide range of halogenated trace gases, with calibration scales linked to both global monitoring networks, i.e. NOAA and AGAGE. A Time of Flight Mass Spectrometer has the advantage to measure a full mass range with a high sensitivity. Other measuring networks use Quadrupole mass spectrometers which need to be tuned to selected masses in order to achieve sufficient sensitivity. The full mass scan information available in the TOF data in combination with the high sensitivity of the instrument opens the possibility for retrospective analysis of the data in the future, as information on all substances which can be trapped and desorbed using our sampling technique are recorded, even though they may not be retrieved at the time of measurements. This will open the opportunity to have a look on historical developments even of yet undiscovered halogenated trace gases or those, which have not been subject to one's research focus until a certain time point but have become interesting later. The full resolution mass spectrometric data will be stored together with all meteorological and other information necessary for later reprocessing. This will constitute a digital air archive, which can also be made available to other research groups for reanalysis.

Hoker, Jesica; Obersteiner, Florian; Bönisch, Harald; Engel, Andreas

2014-05-01

264

"DUST BUSTER" - A Single Photon Ionization TOF MS for Cometary Dusts  

NASA Technical Reports Server (NTRS)

It is hard to predict the properties and composition of dust that will be returned by STARDUST from WED- 2. The most interesting but challenging case would be grains, pg to fg in weight, each carrying its own isotopic signature characteristic of its source zones in a variety of stars. How do we extract the maximum amount of science from such grains? Clearly, the best that can be accomplished is to measure every atom in each grain.Academia Sinica and Argonne National Laboratory (ANL) have entered into a collaboration to develop a SPI TOF MS instrument for analysis of stardust grains. A new instrument will be built at Academia Sinica based on the new TOF mass spectrometer design developed, built and operating at ANL. The instrument is intended for SPI TOF MS analysis of elements from Ca to Cu plus Li after first using SIMS to measure H, C, N, 0, Si, and S. There are still technical challenges facing the technique. We will need to improve submicrometer sample handling, avoid the effects of space charge, and increase the Mamie range of the detector. The most difficult obstacle to overcome may be the fact that the flux density of present high repetition rate, WV lasers is below the level needed to ensure full ionization (saturation) in the source region, which must be several mm in size to achieve the high useful yield needed for analysis of small stardust grains. A potential breakthrough effort is to exploit the novel free electron laser being pioneered at ANL. In principle, this FEL can reach ionization saturation and is tunable up to photon energies of 25 eV, which is higher than the ionization potential of any element.

Chen, C.-Y.; Calaway, W. F.; Lee, Typhoon; Moore, J. F.; Pellin, M. J.; Veryovkin, I. V.

2003-01-01

265

Identification and differentiation of food-related bacteria: A comparison of FTIR spectroscopy and MALDI-TOF mass spectrometry.  

PubMed

The food industry requires easy, accurate, and cost-effective techniques for microbial identification to ensure safe products and identify microbial contaminations. In this work, FTIR spectroscopy and MALDI-TOF mass spectrometry were assessed for their suitability and applicability for routine microbial diagnostics of food-related microorganisms by analyzing their robustness according to changes in incubation time and medium, identification accuracy and their ability to differentiate isolates down to the strain level. Changes in the protocol lead to a significantly impaired performance of FTIR spectroscopy, whereas they had only little effects on MALDI-TOF MS. Identification accuracy was tested using 174 food-related bacteria (93 species) from an in-house strain collection and 40 fresh isolates from routine food analyses. For MALDI-TOF MS, weaknesses in the identification of bacilli and pseudomonads were observed; FTIR spectroscopy had most difficulties in identifying pseudomonads and enterobacteria. In general, MALDI-TOF MS obtained better results (52-85% correct at species level), since the analysis of mainly ribosomal proteins is more robust and seems to be more reliable. FTIR spectroscopy suffers from the fact that it generates a whole-cell fingerprint and intraspecies diversity may lead to overlapping species borders which complicates identification. In the present study values between 56% and 67% correct species identification were obtained. On the opposite, this high sensitivity offers the opportunity of typing below the species level which was not possible using MALDI-TOF MS. Using fresh isolates from routine diagnostics, both techniques performed well with 88% (MALDI-TOF) and 75% (FTIR) correct identifications at species level, respectively. PMID:24878140

Wenning, Mareike; Breitenwieser, Franziska; Konrad, Regina; Huber, Ingrid; Busch, Ulrich; Scherer, Siegfried

2014-08-01

266

Use of the MALDI BioTyper system with MALDI-TOF mass spectrometry for rapid identification of microorganisms.  

PubMed

In a clinical diagnosis microbiology laboratory, the current method of identifying bacterial isolates is based mainly on phenotypic characteristics, for example growth pattern on different media, colony morphology, Gram stain, and various biochemical reactions. These techniques collectively enable great accuracy in identifying most bacterial isolates, but are costly and time-consuming. In our clinical microbiology laboratory, we prospectively assessed the ability of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) to identify bacterial strains that were routinely isolated from clinical samples. Bacterial colonies obtained from a total of 468 strains of 92 bacterial species isolated at the Department of Clinical Laboratory at Chiba University were directly placed on target MALDI plates followed by addition of CHCA matrix solution. The plates were then subjected to MALDI-TOF MS measurement and the microorganisms were identified by pattern matching with the libraries in the BioTyper 2.0 software. Identification success at the species and genus levels was 91.7% (429/468) and 97.0% (454/468), respectively. MALDI-TOF MS is a rapid, simple, and high-throughput proteomic technique for identification of a variety of bacterial species. Because colony-to-colony differences and effects of culture duration on the results are minimal, it can be implemented in a conventional laboratory setting. Although for some pathogens, preanalytical processes should be refined, and the current database should be improved to obtain more accurate results, the MALDI-TOF MS based method performs, in general, as well as conventional methods and is a promising technology in clinical laboratories. PMID:21442367

Sogawa, Kazuyuki; Watanabe, Masaharu; Sato, Kenichi; Segawa, Syunsuke; Ishii, Chisato; Miyabe, Akiko; Murata, Syota; Saito, Tomoko; Nomura, Fumio

2011-06-01

267

A transient tobacco expression system coupled to MALDI-TOF-MS allows validation of the impact of differential targeting on structure and activity of a recombinant therapeutic glycoprotein produced in plants.  

PubMed

Tobacco-based transient expression was employed to elucidate the impact of differential targeting to subcellular compartments on activity and quality of gastric lipase as a model for the production of recombinant glycoproteins in plants. Overall N-linked glycan structures of recombinant lipase were analyzed and for the first time sugar structures of its four individual N-glycosylation sites were determined in situ by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) on a trypsin digest without isolation or deglycosylation of the peptides. Three glycosylation sites contain both complex-type N-glycans and high-mannose-type structures, the fourth is exclusively linked to high-mannose glycans. Although the overall pattern of glycan structures is influenced by the targeting, our results show that the type of glycans found linked to a given Asn residue is largely influenced by the physico-chemical environment of the site. The transient tobacco system combined with MALDI-TOF-MS appears to be a useful tool for the evaluation of glycoprotein production in plants. PMID:14527682

Mokrzycki-Issartel, Nathalie; Bouchon, Bernadette; Farrer, Sibille; Berland, Patricia; Laparra, Hélène; Madelmont, Jean Claude; Theisen, Manfred

2003-09-25

268

Accurate mass measurements for the confirmation of Sudan azo-dyes in hot chilli products by capillary liquid chromatography-electrospray tandem quadrupole orthogonal-acceleration time of flight mass spectrometry.  

PubMed

The potential of capillary liquid chromatography (microLC)-quadrupole/time-of-flight mass spectrometry (Q-TOF MS) for the confirmation of Sudan I, II, III and IV azo-dyes as contaminants in hot-chilli food products was demonstrated. Using the microLC-electrospray ionization (ESI)-Q-TOF MS technique, accurate mass measurements of Sudan dyes were performed both on standard solutions and on matrices. Precision of exact mass measurements was calculated taking into account the ion statistics according to the number of ion sampled in the measurement. Accurate mass measurements by MS/MS experiments were performed to elucidate azo-dye fragmentation patterns. Selectivity of the microLC-Q-TOF MS method was assessed by evaluating matrix suppression effects by pre-column injection of blank hot chilli tomato sauce matrices. The results were compared with those obtained on a LC-triple quadrupole-MS system. Confirmation of Sudan I present in hot chill tomato sauce samples was obtained by accurate mass measurements. In real samples trueness of exact mass measurements was estimated to be 1.6 and 4.4 ppm when calculated for hot chilli tomato sauce and hot chilli tomato with cheese sauce samples, respectively; precision was calculated around 9.5 ppm. PMID:15595660

Calbiani, F; Careri, M; Elviri, L; Mangia, A; Zagnoni, I

2004-11-26

269

Analysis of illicit dietary supplements sold in the Italian market: Identification of a sildenafil thioderivative as adulterant using UPLC-TOF/MS and GC/MS.  

PubMed

Identification of pharmaceutical active ingredients sildenafil and tadalafil and the characterization of a dimethylated thio-derivative of sildenafil, called thioaildenafil or thiodimethylsildenafil, in illicit dietary supplements were described. A multi-residual ultra-performance liquid chromatography-time of flight mass spectrometry (UPLC-TOF/MS) method was developed to screen for the presence of the phosphodiesterase-5 (PDE-5) inhibitors sildenafil, tadalafil, and vardenafil and their analogues thioaildenafil and thiohomosildenafil in powders and pharmaceutical dosage forms. The study was developed in connection with an operation supervised by the Italian Medicines Agency (A.I.F.A.), aimed to monitor dietary supplements in the Italian market. In two of the eleven specimens under investigation, high-resolution mass spectrometry (HR-MS) allowed the identification of the PDE-5 inhibitors sildenafil and tadalafil, while another specimen proved to contain a unapproved dimethylated thioderivative of sildenafil, thioaildenafil or thiodimethylsildenafil, identified for the first time in Italy as adulterant in food supplements. PMID:24796952

Damiano, Fabio; Silva, Claudia; Gregori, Adolfo; Vacondio, Federica; Mor, Marco; Menozzi, Mattia; Di Giorgio, Domenico

2014-05-01

270

LC-Q-TOF-MS/MS determination of darunavir and its metabolites in rat serum and urine: application to pharmacokinetics.  

PubMed

A simple, rapid and reliable liquid chromatography coupled with quadrupole time of flight mass spectrometry (LC-Q-TOF-MS/MS) method was developed and validated for simultaneous determination of darunavir and its metabolites in rat serum and urine. The separation was accomplished on an Agilent RP-18 (250×4.6mm, 5?m) column using 20mM ammonium acetate and methanol (40:60, v/v) as a mobile phase at a flow rate of 1.0mL/min in an isocratic mode. The [M+H](+) ions of darunavir (m/z 548) and metabolites-I (m/z 392) were monitored in positive mode of ionization, while [M-H](-) ion of metabolite-II (m/z 172) in negative mode selectively. The matrix effects of rat serum and urine were found to be negligible and the recoveries were 87-93% for all the analytes. The short and long term stability of darunavir and its metabolites was within acceptable limits and the lower limits of quantification were in the range of 3.63-5.24ng/mL with a linear range of 5-5000ng/mL in rat serum as well as urine. The method exhibited good intra- and inter-day performance in terms of 2.54-8.92% precision and 0-5% accuracy. The method was successfully applied to a single-dose pharmacokinetic study of darunavir boosted with ritonavir in Wistar rats. PMID:24552646

Nageswara Rao, R; Guru Prasad, K

2014-06-01

271

Species identification of staphylococci by amplification and sequencing of the tuf gene compared to the gap gene and by matrix-assisted laser desorption ionization time-of-flight mass spectrometry.  

PubMed

Staphylococcal species, notably, coagulase-negative staphylococci (CoNS), are frequently misidentified using phenotypic methods. The partial nucleotide sequences of the tuf and gap genes were determined in 47 reference strains to assess their suitability, practicability, and discriminatory power as target molecules for staphylococcal identification. The partial tuf gene sequence was selected and further assessed with a collection of 186 strains, including 35 species and subspecies. Then, to evaluate the efficacy of this genotyping method versus the technology of matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS), the 186 strains were identified using MALDI-TOF-MS (Axima® Shimadzu) coupled to the SARAMIS® database (AnagnosTec). The French National Reference Center for Staphylococci identification method was used as a reference. One hundred and eighty-four strains (98.9%) were correctly identified by tuf gene sequencing. Only one strain was misidentified and one was unidentified. MALDI-TOF-MS identified correctly 138 isolates (74.2%). Four strains were misidentified, 39 were unidentified, five were identified at the group (hominis/warneri) level, and one strain was identified at the genus level. These results confirm the value of MALDI-TOF-MS identification for common species in clinical laboratory practice and the value of the partial tuf gene sequence for the identification of all staphylococcal species as required in a reference laboratory. PMID:20967479

Bergeron, M; Dauwalder, O; Gouy, M; Freydiere, A-M; Bes, M; Meugnier, H; Benito, Y; Etienne, J; Lina, G; Vandenesch, F; Boisset, S

2011-03-01

272

Rapid identification of Gram-negative organisms from blood culture bottles using a modified extraction method and MALDI-TOF mass spectrometry.  

PubMed

The application of matrix-assisted laser desorption/ionisation time-of-flight (MALDI-TOF) mass spectrometry (MS) directly to blood culture broth has potential to identify bloodstream infection earlier and facilitate timely management. We prospectively tested a novel, rapid, and inexpensive in-house spin-lysis protocol with formic acid extraction and compared MALDI-TOF MS identification of Gram-negative bacteria with traditional phenotypic methods (Phoenix™) directly from 318 BACTEC™ (Becton Dickinson, Franklin Lakes, USA) blood cultures. The MS score was ?1.7 in 268 (91.8%) monomicrobial broths, with concordance to genus and species level of 100% and 97.0%, respectively. MALDI-TOF MS still has limited capacity to detect all species in polymicrobial broths. PMID:23891220

Gray, Timothy J; Thomas, Lee; Olma, Tom; Iredell, Jonathan R; Chen, Sharon C-A

2013-10-01

273

Characterization of different poly(2-ethyl-2-oxazoline)s via matrix-assisted laser desorption/ionization time-of-flight tandem mass spectrometry.  

PubMed

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) coupled with CID (collision-induced dissociation) has been used for the detailed characterization of two poly(2-ethyl-2-oxazoline)s as part of a continuing study of synthetic polymers by MALDI-TOF MS/MS. These experiments provided information about the variety of fragmentation pathways for poly(oxazoline)s. It was possible to show that, in addition to the eliminations of small molecules, like ethene and hydrogen, the McLafferty rearrangement is also a possible fragmentation route. A library of fragmentation pathways for synthetic polymers was also constructed and such a library should enable the fast and automated data analysis of polymers in the future. PMID:19224528

Baumgaertel, Anja; Weber, Christine; Knop, Katrin; Crecelius, Anna; Schubert, Ulrich S

2009-03-01

274

Evaluation of Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry for Rapid Identification of Beta-Hemolytic Streptococci?  

PubMed Central

This study was undertaken to evaluate matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) for the rapid identification of beta-hemolytic streptococci. We compared Bruker Biotyper 2.0 with Vitek2 coupled to the agglutination test. MALDI-TOF MS analysis of 386 beta-hemolytic streptococcal isolates yielded high-confidence identification to the species level for all 386 isolates. The Vitek2 gave high-confidence identification to the species level for 88% of Streptococcus agalactiae isolates (n = 269/306), 92% of Streptococcus pyogenes isolates (n = 48/52), and 39% of isolates of Streptococcus dysgalactiae serogroups C and G (n = 11/28).

Cherkaoui, Abdessalam; Emonet, Stephane; Fernandez, Jose; Schorderet, Didier; Schrenzel, Jacques

2011-01-01

275

Gold Ion-Angiotensin Peptide Interaction by Mass Spectrometry  

NASA Astrophysics Data System (ADS)

Stimulated by the interest in developing gold compounds for treating cancer, gold ion-angiotensin peptide interactions are investigated by mass spectrometry. Under the experimental conditions used, the majority of gold ion-angiotensin peptide complexes contain gold in the oxidation states I and III. Both ESI-MS and MALDI-TOF MS detect singly/multiply charged ions for mononuclear/multinuclear gold-attached peptides, which are represented as [peptide + a Au(I) + b Au(III) + (e - a -3b) H]e+, where a,b ? 0 and e is charge. ESI-MS data shows singly/multiply charged ions of Au(I)-peptide and Au(III)-peptide complexes. This study reveals that MALDI-TOF MS mainly detects singly charged Au(I)-peptide complexes, presumably due to the ionization process. The electrons in the MALDI plume seem to efficiently reduce Au(III) to Au(I). MALDI also tends to enhance the higher polymeric forms of gold-peptide complexes regardless of the laser power used. Collision-induced dissociation experiments of the mononuclear and dinuclear gold-attached peptide ions for angiotensin peptides show that the gold ion (a soft acid) binding sites are in the vicinity of Cys (a soft ligand), His (a major anchor of peptide for metal ion chelation), and the basic residue Arg. Data also suggests that the abundance of gold-attached peptides increases with higher gold concentration until saturation, after which an increase in gold ion concentration leads to the aggregation and/or precipitation of gold-bound peptides.

Lee, Jenny; Jayathilaka, Lasanthi P.; Gupta, Shalini; Huang, Jin-Sheng; Lee, Bao-Shiang

2012-05-01

276

Accurate characterization of carcinogenic DNA adducts using MALDI tandem time-of-flight mass spectrometry  

NASA Astrophysics Data System (ADS)

Many chemical carcinogens and their in vivo activated metabolites react readily with genomic DNA, and form covalently bound carcinogen-DNA adducts. Clinically, carcinogen-DNA adducts have been linked to various cancer diseases. Among the current methods for DNA adduct analysis, mass spectroscopic method allows the direct measurement of unlabeled DNA adducts. The goal of this study is to explore the use of matrix-assisted laser desorption/ionization tandem time-of-flight mass spectrometry (MALDI-TOF/TOF MS) to determine the identity of carcinogen-DNA adducts. Two of the known carcinogenic DNA adducts, namely N-(2'-deoxyguanosin-8-yl)-2-amino-1-methyl-6-phenyl-imidazo [4,5-b] pyridine (dG-C8-PhIP) and N-(2'-deoxyguanosin-8yl)-4-aminobiphenyl (dG-C8-ABP), were selected as our models. In MALDI-TOF MS measurements, the small matrix ion and its cluster ions did not interfere with the measurements of both selected dG adducts. To achieve a higher accuracy for the characterization of selected dG adducts, 1 keV collision energy in MALDI-TOF/TOF MS/MS was used to measure the adducts. In comparison to other MS/MS techniques with lower collision energies, more extensive precursor ion dissociations were observed. The detection of the corresponding fragment ions allowed the identities of guanine, PhIP or ABP, and the position of adduction to be confirmed. Some of the fragment ions of dG-C8-PhIP have not been reported by other MS/MS techniques.

Barnes, Charles A.; Chiu, Norman H. L.

2009-01-01

277

N-glycosylation analysis by HPAEC-PAD and mass spectrometry.  

PubMed

Changes in protein glycosylation are a hallmark of most types of cancer including ovarian carcinoma. The structural elucidation of glycans is technically challenging and it requires complementary chromatographic and spectroscopic techniques among others. Here, we describe the profiling of N-glycans from glycoproteins of SKOV3 ovarian carcinoma cells by high-performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD) and matrix-assisted laser desorption/ionization with time-of-flight mass spectrometry (MALDI-TOF MS). Mass spectrometry as a complementary method enables precise mass determination of N-glycan mixtures thus corroborating data obtained from HPAEC-PAD mapping in conjunction with reference oligosaccharide structures. PMID:23913225

Kandzia, Sebastian; Costa, Júlia

2013-01-01

278

Comparing the old and new generation SELDI-TOF MS: implications for serum protein profiling  

Microsoft Academic Search

BACKGROUND: Although the PBS-IIc SELDI-TOF MS apparatus has been extensively used in the search for better biomarkers, issues have been raised concerning the semi-quantitative nature of the technique and its reproducibility. To overcome these limitations, a new SELDI-TOF MS instrument has been introduced: the PCS 4000 series. Changes in this apparatus compared to the older one are a.o. an increased

Marie-Christine W Gast; Judith YMN Engwegen; Jan HM Schellens; Jos H Beijnen

2008-01-01

279

Proton transfer reaction time-of-flight mass spectrometry monitoring of the evolution of volatile compounds during lactic acid fermentation of milk.  

PubMed

We apply, for first time, the recently developed proton transfer reaction time-of-flight mass spectrometry (PTR-TOF-MS) apparatus as a rapid method for the monitoring of lactic acid fermentation (LAF) of milk. PTR-TOF-MS has been proposed as a very fast, highly sensitive and versatile technique but there have been no reports of its application to dynamic biochemical processes with relevance to the food industry. LAF is a biochemical-physicochemical dynamic process particularly relevant for the dairy industry as it is an important step in the production of many dairy products. Further, LAF is important in the utilization of the by-products of the cheese industry, such as whey wastewaters. We show that PTR-TOF-MS is a powerful method for the monitoring of major volatile organic chemicals (VOCs) formed or depleted during LAF, including acetaldehyde, diacetyl, acetoin and 2-propanone, and it also provides information about the evolution of minor VOCs such as acetic acid, 2,3-pentanedione, ethanol, and off-flavor related VOCs such as dimethyl sulfide and furfural. This can be very important considering that the conventional measurement of pH decrease during LAF is often ineffective due to the reduced response of pH electrodes resulting from the formation of protein sediments. Solid-phase microextraction gas chromatography/mass spectrometry (SPME-GC/MS) data on the inoculated milk base and final fermented product are also presented to supporting peak identification. We demonstrate that PTR-TOF-MS can be used as a rapid, efficient and non-invasive method for the monitoring of LAF from headspace, supplying important data about the quality of the final product and that it may be used to monitor the efficacy of manufacturing practices. PMID:20552689

Soukoulis, Christos; Aprea, Eugenio; Biasioli, Franco; Cappellin, Luca; Schuhfried, Erna; Märk, Tilmann D; Gasperi, Flavia

2010-07-30

280

Glycan analysis of Prostate Specific Antigen (PSA) directly from the intact glycoprotein by HR-ESI/TOF-MS.  

PubMed

Glycans are important modulators of the biological function of proteins and are normally characterized from proteolytic glycopeptides or from (N-)glycans released enzymatically by glycosidase treatment or chemically by hydrazinolysis. We demonstrate that glycan compositions can easily be determined directly by LC-ESI/TOF-MS from intact glycoproteins even with a very complex glycosylation pattern. Interpretation of isotopically resolved mass spectra of prostate specific antigen (PSA) using bioinformatics tools gives within a few hours the glycan compositions of 38 glycoforms. PMID:24393138

Behnken, Henning N; Ruthenbeck, Alexandra; Schulz, Jan-Mirco; Meyer, Bernd

2014-02-01

281

Porous anodic alumina membrane as a sample support for MALDI-TOF MS analysis of salt-containing proteins  

Microsoft Academic Search

Matrix-assisted laser desorption\\/ionization time-of-flight mass spectrometric (MALDI-TOF MS) analysis of proteins in salt-containing\\u000a solution was performed for the first time using porous anodic alumina (PAA) membrane as sample support. The resulting spectral\\u000a quality of proteins under standard sample preparation conditions was superior to that of normal metal sample stages. Analysis\\u000a of phosphate-doped protein solutions indicated that porous anodic alumina membranes

Yuebo Wang; Xinghua Xia; Yinlong Guo

2005-01-01

282

PHARMACOKINETICS, BIOAVAILABILITY, AND METABOLISM OF 2,3,5,4?-TETRAHYDROXYSTILBENE-2-O-?;-D-GLUCOSIDE IN RATS BY ULTRA PERFORMANCE LIQUID CHROMATOGRAPHY–QUADRUPOLE TIME-OF-FLIGHT MASS SPECTROMETRY AND HIGH PERFORMANCE LIQUID CHROMATOGRAPHY-ULTRAVIOLET DETECTION  

Microsoft Academic Search

2,3,5,4?-tetrahydroxystilbene-2-O-?-D-glucoside (THSG), a natural product purified from the Chinese medical herb Polygoni multiflori Radix, has been demonstrated to possess many pharmacological activities, including antioxidant, anti-inflammatory, hepatoprotective and antitumor properties. Ultra performance liquid chromatography– time-of-flight mass spectrometry (UPLC-Q-TOF\\/MS) and high performance liquid chromatography-ultraviolet detection (HPLC-UV) methods were developed for the pharmacokinetics, bioavailability, absorption and metabolism studies of THSG in rats following

Ying-Yong Zhao; Xian-Long Cheng; Feng Wei; Xiao-Qiang Han; Xin-Yue Xiao; Rui-Chao Lin

2012-01-01

283

Clinical and Microbiological Features of a Cystic Fibrosis Patient Chronically Colonized with Pandoraea sputorum Identified by Combining 16S rRNA Sequencing and Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry  

PubMed Central

Clonal isolates identified as various nonfermentative Gram-negative bacilli over a 5-year period from sputum cultures of a 30-year-old cystic fibrosis patient were successfully reidentified as Pandoraea sputorum by combining 16S rRNA sequencing and matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS). Decreased lung function improved after 1 year of azithromycin and inhaled 7%-hypertonic saline treatment.

Fernandez-Olmos, A.; Morosini, M. I.; Lamas, A.; Garcia-Castillo, M.; Garcia-Garcia, L.; Maiz, L.

2012-01-01

284

Misidentification of Saprochaete clavata as Magnusiomyces capitatus in Clinical Isolates: Utility of Internal Transcribed Spacer Sequencing and Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry and Importance of Reliable Databases.  

PubMed

Saprochaete clavata and Magnusiomyces capitatus are human pathogens that are frequently mistaken for each other due to their similar phenotypes and erroneous or limited databases. Based on internal transcribed spacer (ITS) sequences, we propose species-specific carbon assimilation patterns and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) fingerprints that enable the identification of S. clavata, M. capitatus, and Galactomyces candidus to the species level. PMID:24696028

Desnos-Ollivier, Marie; Blanc, Catherine; Garcia-Hermoso, Dea; Hoinard, Damien; Alanio, Alexandre; Dromer, Françoise

2014-06-01

285

Comparison of the Accuracy of Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry with That of Other Commercial Identification Systems for Identifying Staphylococcus saprophyticus in Urine  

PubMed Central

Among 30 urinary isolates of Staphylococcus saprophyticus identified by sequencing methods, the rate of accurate identification was 100% for Bruker Biotyper matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS), 86.7% for the Phoenix PID and Vitek 2 GP systems, 93.3% for the MicroScan GP33 system, and 46.7% for the BBL CHROMagar Orientation system.

Lee, Tai-Fen; Lee, Hao; Chen, Chung-Ming; Du, Shin-Hei; Cheng, Ya-Chih; Hsu, Chen-Ching; Chung, Meng-Yu; Teng, Shih-Hua; Teng, Lee-Jene

2013-01-01

286

A rapid method for simultaneous determination of 14 phenolic compounds in Radix Puerariae using microwave-assisted extraction and ultra high performance liquid chromatography coupled with diode array detection and time-of-flight mass spectrometry  

Microsoft Academic Search

A microwave-assisted extraction (MAE) and ultra high performance liquid chromatography coupled with diode array detection and time-of-flight mass spectrometry (UHPLC-DAD-TOF-MS) method was developed for simultaneous determination of 14 phenolic compounds in the root of Pueraria lobata (Wild.) Ohwi and Pueraria thomsonii Benth. Operational conditions of MAE were optimized by central composite design (CCD). The optimized result was 65% ethanol as

G. Du; H. Y. Zhao; Q. W. Zhang; G. H. Li; F. Q. Yang; Y. Wang; Y. C. Li

2010-01-01

287

Analyses of macrolide antibiotic residues in eggs, raw milk, and honey using both ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry and high-performance liquid chromatography/tandem mass spectrometry.  

PubMed

Two liquid chromatography mass spectrometric techniques, i.e. ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UPLC/Q-Tof MS) and high-performance liquid chromatography/tandem mass spectrometry (LC/MS/MS), were used for quantification, confirmation or identification of six macrolide antibiotic residues and/or their degradation products in eggs, raw milk, and/or honey. Macrolides were extracted from food samples by acetonitrile or phosphate buffer (0.1 M, pH 8.0), and sample extracts were further cleaned up using solid-phase extraction cartridges. UPLC/Q-Tof data were acquired in Tof MS full scan mode that allowed both quantification and confirmation of macrolides, and identification of their degradation products. LC/MS/MS data acquisition was achieved using multiple reaction monitoring (MRM), i.e. two transitions, to provide a high degree of sensitivity and repeatability. Matrix-matched standard calibration curves with the use of roxithromycin as an internal standard were utilized to achieve the best accuracy of the method. Both techniques demonstrated good quantitative performance in terms of accuracy and repeatability. LC/MS/MS had advantages over UPLC/Q-Tof MS in that its limits of detection were lower and repeatability was somewhat better. UPLC/Q-Tof provided ultimate and unequivocal confirmation of positive findings, and allowed degradation product identification based on accurate mass. The combination of the two techniques can be very beneficial or complementary in routine analysis of macrolide antibiotic residues and their degradation products in food matrices to ensure the safety of food supply. PMID:17768705

Wang, Jian; Leung, Daniel

2007-01-01

288

Mass Spectrometry for Proteomics  

PubMed Central

Summary Mass spectrometry has been widely used to analyze biological samples and has evolved into an indispensable tool for proteomics research. Our desire to understand the proteome has led to new technologies that push the boundary of mass spectrometry capabilities, which in return has allowed mass spectrometry to address an ever-increasing array of biological questions. The recent development of a novel mass spectrometer (Orbitrap) and new dissociation methods such as electron transfer dissociation have made possible exciting new areas of proteomic application. Although bottom-up proteomics (analysis of proteolytic peptide mixtures) remains the workhorse for proteomic analysis, middle- and top-down strategies (analysis of longer peptides and intact proteins, respectively) should allow more complete characterization of protein isoforms and post-translational modifications. Finally, stable isotope labeling strategies have transformed mass spectrometry from merely descriptive to a tool for measuring dynamic changes in protein expression, interaction and modification.

Han, Xuemei; Aslanian, Aaron; Yates, John R.

2008-01-01

289

Rapid detection of antibiotic resistance based on mass spectrometry and stable isotopes.  

PubMed

With the emergence and growing complexity of bacterial drug resistance, rapid and reliable susceptibility testing has become a topical issue. Therefore, new technologies that assist in predicting the effectiveness of empiric antibiotic therapy are of great interest. Although the use of matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS) for the rapid detection of antibiotic resistance is an attractive option, the current methods for MALDI-TOF MS susceptibility testing are restricted to very limited conditions. Here, we describe a technique that may allow for rapid susceptibility testing to an extent that is comparable to phenotypic methods. The test was based on a stable isotope labelling by amino acids in cell culture (SILAC)-like approach. This technique was used to visualise the growth of bacteria in the presence of an antibiotic. Pseudomonas aeruginosa was chosen as the model organism, and strains were incubated in normal medium, medium supplemented with (13)C6-(15)?N2-labelled lysine and medium supplemented with labelled lysine and antibiotic. Peak shifts occurring due to the incorporation of the labelled amino acids were detected by MALDI-TOF MS. Three antibiotics with different mechanisms of action, meropenem, tobramycin and ciprofloxacin, were tested. A semi-automated algorithm was created to enable rapid and unbiased data evaluation. With the proposed test, a clear distinction between resistant and susceptible isolates was possible for all three antibiotics. The application of SILAC technology for the detection of antibiotic resistance may contribute to accelerated and reliable susceptibility testing. PMID:24338093

Jung, J S; Eberl, T; Sparbier, K; Lange, C; Kostrzewa, M; Schubert, S; Wieser, A

2014-06-01

290

MALDI-TOF mass spectrometry as a tool for the discrimination of high-risk Escherichia coli clones from phylogenetic groups B2 (ST131) and D (ST69, ST405, ST393).  

PubMed

Reliable, quick and low-cost methods are needed for the early detection of multidrug-resistant and highly virulent high-risk B2 and D Escherichia coli clones or clonal complexes (HiRCC). Matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS) seems to have a good discriminatory potential at different subspecies levels, but it was never evaluated for the discrimination of E. coli clones. We assessed the potential of MALDI-TOF MS coupled to multivariate data analysis to discriminate representative E. coli B2 and D HiRCC. Seventy-three E. coli isolates from B2 (including ST131 and B2 non-ST131 clones) and D (ST69, ST393, ST405) with variable pulsed-field gel electrophoresis (PFGE) patterns, origins and dates (1980-2010) were tested. MS spectra were acquired from independent extracts obtained from different plate cultures in two different Microflex LT MALDI-TOF devices (Bruker) after a standard extraction procedure. MALDI-TOF MS fingerprinting analysis revealed a good discriminatory ability between the four HiRCC analysed (ST131, ST69, ST405, ST393) and between B2 ST131 and other B2 non-ST131 isolates. Clusters defined by MALDI-TOF MS were consistent with the clonal complexes assigned by multilocus sequence typing (MLST), although differences were detected regarding the composition of clusters obtained by the comparison of PFGE profiles. We demonstrate, for the first time, that characteristic mass fingerprints of different E. coli HiRCC are sufficiently discriminatory and robust to enable their differentiation by MALDI-TOF MS, which might represent a promising tool for the optimisation of infection control, individual patient management and large-scale epidemiological studies of public health relevance. The good correlation between phenotypic and genotypic features further corroborates phylogenetic relationships delineated by MLST. PMID:24599708

Novais, A; Sousa, C; de Dios Caballero, J; Fernandez-Olmos, A; Lopes, J; Ramos, H; Coque, T M; Cantón, R; Peixe, L

2014-08-01

291

Analysis of ?-blockers in groundwater using large-volume injection coupled-column reversed-phase liquid chromatography with fluorescence detection and liquid chromatography time-of-flight mass spectrometry.  

PubMed

Atenolol, nadolol, metoprolol, bisoprolol and betaxolol were simultaneously determined in groundwater samples by large-volume injection coupled-column reversed-phase liquid chromatography with fluorescence detection (LVI-LC-LC-FD) and liquid chromatography-time-of-flight mass spectrometry (LC-TOF-MS). The LVI-LC-LC-FD method combines analyte isolation, preconcentration and determination into a single step. Significant reductions in costs for sample pre-treatment (solvent and solid phases for clean up) and method development times are also achieved. Using LC-TOF-MS, accurate mass measurements within 3?ppm error were obtained for all of the ?-blockers studied. Empirical formula information can be obtained by this method, allowing the unequivocal identification of the target compounds in the samples. To increase the sensitivity, a solid-phase extraction step with Oasis MCX cartridge was carried out yielding recoveries of 79-114% (n=5) with RSD 2-7% for the LC-TOF-MS method. SPE gives a high purification of ?-blockers compared with the existing methods. A 100% methanol wash was allowed for these compounds with no loss of analytes. Limit of quantification was 1-7?ng/L for LVI-LC-LC-FD and 0.25-5?ng/L for LC-TOF-MS. As a result of selective extraction and effective removal of coextractives, no matrix effect was observed in LVI-LC-LC-FD and LC-TOF-MS analyses. The methods were applied to detect and quantify ?-blockers in groundwater samples of Almería (Spain). PMID:21710696

Galera, María M; Vázquez, Piedad P; Vázquez, María Del Mar P; García, María Dolores G; Amate, Carmen F

2011-06-27

292

Proteomic study of serum using gel chromatography and MALDI-TOF MS reveals diagnostic biomarkers in male patients with liver-cancer  

NASA Astrophysics Data System (ADS)

Human serum has been widely employed clinically for diagnosing various fatal diseases. However, the concentration of most proteins in human serum is too low to be directly measured using normal analytical methods. In order to obtain reliable analytical results from proteomic analysis of human serum, appropriate sample preparation is essential. A combined off-line analytical technique of gel chromatography and matrix-assisted laser desorption ionization/time of flight mass spectrometry (MALDI-TOF MS) has been successfully established to separate proteins for MS analysis. Using these combined techniques, 176 mass signal peaks of proteins/peptides were found in 6 of 18 fractions from normal male serum (NMS) in the presence of buffer consisting of NH4HCO3 and acetonitrile. A simple gel chromatography column packed with Sephadex G-50 removed most signal-suppressing compounds such as salts and high abundance proteins (HAP). The molecular mass to charge (m/z) ratios of differential peptides revealed in serum of male patient with liver-cancer (LCMPS) compared to NMS were 5365, 5644 and 6462, and these peptides can be used as biomarkers to clinically diagnose liver-cancer. The simple and convenient chromatographic method described here is not only superior to recently described HPLC separation for MS analysis, but also reveals many novel and significant serum biomarkers for the clinical diagnosis of various diseases.

Zeng, Xin-Hua; Huang, He-Qing; Chen, Dong-Shi; Jin, Hong-Wei; Huang, Hui-Ying

2007-03-01

293

Mass Spectrometry as a Powerful Analytical Technique for the Structural Characterization of Synthesized and Natural Products  

NASA Astrophysics Data System (ADS)

Mass spectrometry is an important tool for the identification and structural elucidation of natural and synthesized compounds. Its high sensitivity and the possibility of coupling liquid chromatography with mass spectrometry detection make it a technique of choice for the investigation of complex mixtures like raw natural extracts. The mass spectrometer is a universal detector that can achieve very high sensitivity and provide information on the molecular mass. More detailed information can be subsequently obtained by resorting to collision-induced dissociation tandem mass spectrometry (CID-MS/MS). In this review, the application of mass spectrometric techniques for the identification of natural and synthetic compounds is presented. The gas-phase fragmentation patterns of a series of four natural flavonoid glycosides, three synthesized benzodiazepines and two synthesized quinoxalinone derivatives were investigated using electrospray ionization mass spectrometry (ESI-MS) and tandem mass spectrometry techniques. Exact accurate masses were measured using a modorate resolution quadrupole orthogonal time-of-flight QqTOF-MS/MS hybrid mass spectrometer instrument. Confirmation of the molecular masses and the chemical structures of the studied compounds were achieved by exploring the gas-phase breakdown routes of the ionized molecules. This was rationalized by conducting low-energy collision CID-MS/MS analyses (product ion- and precursor ion scans) using a conventional quadrupole hexapole-quadrupole (QhQ) tandem mass spectrometer.

Es-Safi, Nour-Eddine; Essassi, El Mokhtar; Massoui, Mohamed; Banoub, Joseph

294

[The mass-spectrometry studies of the interaction of polyhexamethyleneguanidine with lipids].  

PubMed

In this work the integral components of the cytoplasmic membrane, lecithin and cholesterol were used for mass spectrometry analysis carried out on polyhexamethyleneguanidine (PHMG) mixtures with lipids. The study was performed by mass-spectrometry methods of the MALDI-TOF MS. Our results showed that despite the common use of PHGM polymer derivatives as disinfectants the persistent intermolecular complexes of PHMG oligomers with lipids were not formed. The binding of polycation PHMG with the membrane has been explained by the model proposed. According to this model PHGM can adhere to negatively charged plasma membrane of bacterial cell due to electrostatic interaction and the formation of loop-like structures. Similar stereochemistry mechanism makes the adsorption of the investigated polycation to membrane robust. The mechanism described together with additional destructive factors provides a reasonable explanation for the PHMG induced damage of bacterial cell plasma membrane and the biocide action of disinfectants prepared on the basis of the PHMG salts. PMID:24834718

Lysytsia, A V; Rebriiev, A V

2014-01-01

295

Identification of in vitro and in vivo metabolites of isoimperatorin using liquid chromatography/mass spectrometry.  

PubMed

The objective of the present study was to develop a practical strategy for the identification of metabolites following the in vivo metabolism and in vitro microbial biotransformation of isoimperatorin using liquid chromatography hybrid triple quadrupole-linear ion trap mass spectrometry (LC/QTRAP-MS) and liquid chromatography time of flight mass spectrometry (LC/TOF-MS). As a result, 19 metabolites were characterised in rat urine, plasma, bile and faeces after the oral administration of isoimperatorin and 13 products were identified in the sample from the transformation. Four metabolites were prepared by in vitro microbial biotransformation, and one was confirmed to be a novel compound. The side chain of isoimperatorin was found to be the primary metabolic site that underwent oxidation metabolism both in vivo and in vitro, and the metabolism of isoimperatorin in vivo and in vitro has good correlation. This is the first study of the metabolism of isoimperatorin in vivo. PMID:23768368

Shi, Xiaowei; Liu, Man; Zhang, Min; Zhang, Kerong; Liu, Songchen; Qiao, Shi; Shi, Rui; Jiang, Xijuan; Wang, Qiao

2013-11-01

296

Fourier Transform Mass Spectrometry.  

ERIC Educational Resources Information Center

Discusses the nature of Fourier transform mass spectrometry and its unique combination of high mass resolution, high upper mass limit, and multichannel advantage. Examines its operation, capabilities and limitations, applications (ion storage, ion manipulation, ion chemistry), and future applications and developments. (JN)

Gross, Michael L.; Rempel, Don L.

1984-01-01

297

Microorganism Identification Based On MALDI-TOF-MS Fingerprints  

NASA Astrophysics Data System (ADS)

Advances in MALDI-TOF mass spectrometry have enabled the ­development of a rapid, accurate and specific method for the identification of bacteria directly from colonies picked from culture plates, which we have named the MALDI Biotyper. The picked colonies are placed on a target plate, a drop of matrix solution is added, and a pattern of protein molecular weights and intensities, "the protein fingerprint" of the bacteria, is produced by the MALDI-TOF mass spectrometer. The obtained protein mass fingerprint representing a molecular signature of the microorganism is then matched against a database containing a library of previously measured protein mass fingerprints, and scores for the match to every library entry are produced. An ID is obtained if a score is returned over a pre-set threshold. The sensitivity of the techniques is such that only approximately 104 bacterial cells are needed, meaning that an overnight culture is sufficient, and the results are obtained in minutes after culture. The improvement in time to result over biochemical methods, and the capability to perform a non-targeted identification of bacteria and spores, potentially makes this method suitable for use in the detect-to-treat timeframe in a bioterrorism event. In the case of white-powder samples, the infectious spore is present in sufficient quantity in the powder so that the MALDI Biotyper result can be obtained directly from the white powder, without the need for culture. While spores produce very different patterns from the vegetative colonies of the corresponding bacteria, this problem is overcome by simply including protein fingerprints of the spores in the library. Results on spores can be returned within minutes, making the method suitable for use in the "detect-to-protect" timeframe.

Elssner, Thomas; Kostrzewa, Markus; Maier, Thomas; Kruppa, Gary

298

Environmental Mass Spectrometry  

NASA Astrophysics Data System (ADS)

Environmental mass spectrometry is an important branch of science because it provides many of the data that underlie policy decisions that can directly influence the health of people and ecosystems. Environmental mass spectrometry is currently undergoing rapid development. Among the most relevant directions are a significant broadening of the lists of formally targeted compounds; a parallel interest in nontarget chemicals; an increase in the reliability of analyses involving accurate mass measurements, tandem mass spectrometry, and isotopically labeled standards; and a shift toward faster high-throughput analysis, with minimal sample preparation, involving various approaches, including ambient ionization techniques and miniature instruments. A real revolution in analytical chemistry could be triggered with the appearance of robust, simple, and sensitive portable mass spectrometers that can utilize ambient ionization techniques. If the cost of such instruments is reduced to a reasonable level, mass spectrometers could become valuable household devices.

Lebedev, Albert T.

2013-06-01

299

OmpU as a biomarker for rapid discrimination between toxigenic and epidemic Vibrio cholerae O1/O139 and non-epidemic Vibrio cholerae in a modified MALDI-TOF MS assay  

PubMed Central

Background Cholera is an acute diarrheal disease caused by Vibrio cholerae. Outbreaks are caused by a genetically homogenous group of strains from serogroup O1 or O139 that are able to produce the cholera toxin. Rapid detection and identification of these epidemic strains is essential for an effective response to cholera outbreaks. Results The use of ferulic acid as a matrix in a new MALDI-TOF MS assay increased the measurable mass range of existing MALDI-TOF MS protocols for bacterial identification. The assay enabled rapid discrimination between epidemic V. cholerae O1/O139 strains and other less pathogenic V. cholerae strains. OmpU, an outer membrane protein whose amino acid sequence is highly conserved among epidemic strains of V. cholerae, appeared as a discriminatory marker in the novel MALDI-TOF MS assay. Conclusions The extended mass range of MALDI-TOF MS measurements obtained by using ferulic acid improved the screening for biomarkers in complex protein mixtures. Differences in the mass of abundant homologous proteins due to variation in amino acid sequences can rapidly be examined in multiple samples. Here, a rapid MALDI-TOF MS assay was developed that could discriminate between epidemic O1/O139 strains and other less pathogenic V. cholerae strains based on differences in mass of the OmpU protein. It appeared that the amino acid sequence of OmpU from epidemic V. cholerae O1/O139 strains is unique and highly conserved.

2014-01-01

300

MALDI-TOF mass spectrometry analysis of amphipol-trapped membrane proteins.  

PubMed

Amphipols (APols) are amphipathic polymers with the ability to substitute detergents to keep membrane proteins (MPs) soluble and functional in aqueous solutions. APols also protect MPs against denaturation. Here, we have examined the ability of APol-trapped MPs to be analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). For that purpose, we have used ionic and nonionic APols and as model proteins (i) the transmembrane domain of Escherichia coli outer membrane protein A, a ?-barrel, eubacterial MP, (ii) Halobacterium salinarum bacteriorhodopsin, an ?-helical archaebacterial MP with a single cofactor, and (iii, iv) two eukaryotic MP complexes comprising multiple subunits and many cofactors, cytochrome b(6)f from the chloroplast of the green alga Chlamydomonas reinhardtii and cytochrome bc(1) from beef heart mitochondria. We show that these MP/APol complexes can be readily analyzed by MALDI-TOF-MS; most of the subunits and some lipids and cofactors were identified. APols alone, even ionic ones, had no deleterious effects on MS signals and were not detected in mass spectra. Thus, the combination of MP stabilization by APols and MS analyses provides an interesting new approach to investigating supramolecular interactions in biological membranes. PMID:22703540

Bechara, Chérine; Bolbach, Gérard; Bazzaco, Paola; Sharma, K Shivaji; Durand, Grégory; Popot, Jean-Luc; Zito, Francesca; Sagan, Sandrine

2012-07-17

301

Improved Short-Sequence-Repeat Genotyping of Mycobacterium avium subsp. paratuberculosis by Using Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry  

PubMed Central

Accurate sequence analysis of mononucleotide repeat regions is difficult, complicating the use of short sequence repeats (SSRs) as a tool for bacterial strain discrimination. Although multiple SSR loci in the genome of Mycobacterium avium subsp. paratuberculosis allow genotyping of M. avium subsp. paratuberculosis isolates with high discriminatory power, further characterization of the most discriminatory loci is limited due to inherent difficulties in sequencing mononucleotide repeats. Here, a method was evaluated using matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) as an alternative to Sanger sequencing to further differentiate the dominant mycobacterial interspersed repetitive-unit (MIRU)–variable-number tandem-repeat (VNTR) M. avium subsp. paratuberculosis type (n = 37) in Canadian dairy herds by targeting a highly discriminatory mononucleotide SSR locus. First, PCR-amplified DNA was digested with two restriction enzymes to yield a sufficiently small fragment containing the SSR locus. Second, MALDI-TOF MS was performed to identify the mass, and thus repeat length, of the target. Sufficiently intense, discriminating spectra were obtained to determine repeat lengths up to 15, an improvement over the limit of 11 using traditional sequencing techniques. Comparison to synthetic oligonucleotides and Sanger sequencing results confirmed a valid and reproducible assay that increased discrimination of the dominant M. avium subsp. paratuberculosis MIRU-VNTR type. Thus, MALDI-TOF MS was a reliable, fast, and automatable technique to accurately resolve M. avium subsp. paratuberculosis genotypes based on SSRs.

Ahlstrom, Christina; Barkema, Herman W.

2014-01-01

302

Experimental validation of an effective carbon number-based approach for the gas chromatography-mass spectrometry quantification of 'compounds lacking authentic standards or surrogates'.  

PubMed

For the quantitative analysis of 'compounds lacking authentic standards or surrogates' (CLASS) in environmental media, we previously introduced an effective carbon number (ECN) approach to develop an empirical equation for the prediction of their response factor (RF). In this research, a series of laboratory experiments were carried out to benchmark the reliability of an ECN approach for sorbent tube/thermal desorption/gas chromatography (GC)/mass spectrometry (MS) applications. First, the ECN values were determined using external calibration data from 25 reference volatile organic compounds (VOCs) using two MS dectectors (quadrupole (Q) and time-of-flight (TOF)). Then, a certified standard mixture of 54 VOCs was analyzed by each system as a simulated unknown sample. The analytical bias, assessed in terms of percentage difference (PD) between the certified and ECN-predicted mass values, averaged 19.2±16.1% (TOF-MS) and 28.2±27.6% (Q-MS). The bias using a more simplified carbon number (CN)-based prediction increased considerably, yielding 53.4±53.3% (TOF-MS) and 61.7±81.3% (Q-MS). However, the bias obtained using the ECN-based prediction decreased significantly to yield average PD values of 9.84±7.28% (TOF-MS) and 16.8±8.35% (Q-MS), if the comparison was limited to 26 (out of 54) VOCs with CN?4 (i.e., 25 aromatics and hexachlorobutadiene). PMID:24856509

Kim, Yong-Hyun; Kim, Ki-Hyun; Szulejko, Jan E; Bae, Min-Suk; Brown, Richard J C

2014-06-01

303

A generic screening methodology for horse doping control by LC-TOF-MS, GC-HRMS and GC-MS.  

PubMed

In the present study a general screening protocol was developed to detect prohibited substances and metabolites for doping control purposes in equine sports. It was based on the establishment of a unified sample preparation and on the combined implementation of liquid and gas chromatographic MS analysis. The sample pretreatment began with two parallel procedures: enzymatic hydrolysis of sulfate and glucuronide conjugates, and methanolysis of the 17?-sulfate steroid conjugates. The extracts were treated for LC-TOF-MS, GC-HRMS and GC-MS assays. The majority of the prohibited substances were identified through a high mass accuracy technique, such as LC-TOF-MS, without prior derivatization. The sample preparation procedure included the formation of methylated and trimethylsilylated derivatives common in toxicological GC-MS libraries. The screening method was enhanced by post-run library searching using automated mass spectral deconvolution and identification system (AMDIS) combined with deconvolution reporting software (DRS). The current methodology is able to detect the presence of more than 350 target analytes in horse urine and may easily incorporate a lot of new substances without changes in chromatography. The full scan acquisition allows retrospective identification of prohibited substances in stored urine samples after reprocessing of the acquired data. Validation was performed for sixty representative compounds and included limit of detection, matrix interference - specificity, extraction recovery, precision, mass accuracy, matrix effect and carry over contamination. The suitability of the method was demonstrated with previously declared positive horse urine samples. PMID:24185097

Kioussi, Maroula K; Lyris, Emmanouil M; Angelis, Yiannis S; Tsivou, Maria; Koupparis, Michael A; Georgakopoulos, Costas G

2013-12-15

304

Determination of Bioactive Peptide Molecular Mass Using Electrospray and Matrix Assisted Laser Desorption Ionization Mass Spectrometry.  

National Technical Information Service (NTIS)

Twelve bioactive peptides, ranging in molecular masses from 600 and 4500 u, were selected for ESI-MS and MALDI-TOF-MS analysis in order to assess the spectrometric data that could be accessed for rapid CB screening purposes. Monoisotopic molecular mass da...

P. A. D'Agostino J. R. Hancock L. R. Provost J. A. Tornes Y. Dai

1998-01-01

305

MALDI-TOF MS characterization of glycation products of whey proteins in a glucose/galactose model system and lactose-free milk.  

PubMed

The major modifications induced by thermal treatment of whey proteins ?-lactalbumin (?-La) and ?-lactoglobulin (?-Lg) in a model system mimicking lactose-free milk (L(-) sugar mix) were investigated by matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS). The analysis of the intact ?-La revealed species with up to 7 and 14 adducts from lactose and sugar mix, respectively, whereas for ?-Lg 3 and up to 5 sugar moieties were observed in the case of lactose and sugar mix experiments, respectively. A partial enzymatic hydrolysis with endoproteinase AspN prior to mass spectrometric analysis allowed the detection of further modifications and their localization in the amino acid sequence. Using ?-cyano-4-chlorocinnamic acid as MALDI matrix, it could be shown that heating ?-La and ?-Lg with glucose or galactose led to the modification of lysine residues that are not glycated by lactose. The higher glycation degree of whey proteins in a lactose-free milk system relative to normal milk with lactose reflects the higher reactivity of monosaccharides compared to the parent disaccharide. Finally, the analysis of the whey extract of a commercial lactose-free milk sample revealed that the two whey proteins were present as three main forms (native, single, and double hexose adducts). PMID:21319853

Carulli, Saverio; Calvano, Cosima D; Palmisano, Francesco; Pischetsrieder, Monika

2011-03-01

306

Identification of Gram-Positive Cocci by Use of Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry: Comparison of Different Preparation Methods and Implementation of a Practical Algorithm for Routine Diagnostics  

PubMed Central

This study compared three sample preparation methods (direct transfer, the direct transfer-formic acid method with on-target formic acid treatment, and ethanol-formic acid extraction) for the identification of Gram-positive cocci with matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS). A total of 156 Gram-positive cocci representing the clinically most important genera, Aerococcus, Enterococcus, Staphylococcus, and Streptococcus, as well as more rare genera, such as Gemella and Granulicatella, were analyzed using a Bruker MALDI Biotyper. The rate of correct genus-level identifications was approximately 99% for all three sample preparation methods. The species identification rate was significantly higher for the direct transfer-formic acid method and ethanol-formic acid extraction (both 77.6%) than for direct transfer (64.1%). Using direct transfer-formic acid compared to direct transfer, the total time to result was increased by 22.6%, 16.4%, and 8.5% analyzing 12, 48, and 96 samples per run, respectively. In a subsequent prospective study, 1,619 clinical isolates of Gram-positive cocci were analyzed under routine conditions by MALDI-TOF MS, using the direct transfer-formic acid preparation, and by conventional biochemical methods. For 95.6% of the isolates, a congruence between conventional and MALDI-TOF MS identification was observed. Two major limitations were found using MALDI-TOF MS: the differentiation of members of the Streptococcus mitis group and the identification of Streptococcus dysgalactiae. The Bruker MALDI Biotyper system using the direct transfer-formic acid sample preparation method was shown to be a highly reliable tool for the identification of Gram-positive cocci. We here suggest a practical algorithm for the clinical laboratory combining MALDI-TOF MS with phenotypic and molecular methods.

Schulthess, Bettina; Brodner, Katharina; Bloemberg, Guido V.; Zbinden, Reinhard; Bottger, Erik C.

2013-01-01

307

Identification of Gram-positive cocci by use of matrix-assisted laser desorption ionization-time of flight mass spectrometry: comparison of different preparation methods and implementation of a practical algorithm for routine diagnostics.  

PubMed

This study compared three sample preparation methods (direct transfer, the direct transfer-formic acid method with on-target formic acid treatment, and ethanol-formic acid extraction) for the identification of Gram-positive cocci with matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). A total of 156 Gram-positive cocci representing the clinically most important genera, Aerococcus, Enterococcus, Staphylococcus, and Streptococcus, as well as more rare genera, such as Gemella and Granulicatella, were analyzed using a Bruker MALDI Biotyper. The rate of correct genus-level identifications was approximately 99% for all three sample preparation methods. The species identification rate was significantly higher for the direct transfer-formic acid method and ethanol-formic acid extraction (both 77.6%) than for direct transfer (64.1%). Using direct transfer-formic acid compared to direct transfer, the total time to result was increased by 22.6%, 16.4%, and 8.5% analyzing 12, 48, and 96 samples per run, respectively. In a subsequent prospective study, 1,619 clinical isolates of Gram-positive cocci were analyzed under routine conditions by MALDI-TOF MS, using the direct transfer-formic acid preparation, and by conventional biochemical methods. For 95.6% of the isolates, a congruence between conventional and MALDI-TOF MS identification was observed. Two major limitations were found using MALDI-TOF MS: the differentiation of members of the Streptococcus mitis group and the identification of Streptococcus dysgalactiae. The Bruker MALDI Biotyper system using the direct transfer-formic acid sample preparation method was shown to be a highly reliable tool for the identification of Gram-positive cocci. We here suggest a practical algorithm for the clinical laboratory combining MALDI-TOF MS with phenotypic and molecular methods. PMID:23554198

Schulthess, Bettina; Brodner, Katharina; Bloemberg, Guido V; Zbinden, Reinhard; Böttger, Erik C; Hombach, Michael

2013-06-01

308

Mass Spectrometry for the Masses  

ERIC Educational Resources Information Center

A simple, qualitative experiment is developed for implementation, where the gas chromatography-mass spectrometry (GC-MS) plays an important role, into the laboratory curriculum of a chemistry course designed for nonscience majors. This laboratory experiment is well suited for the students as it helps them to determine the validity of their…

Persinger, Jared D.; Hoops, Geoffrey, C.; Samide, Michael J.

2004-01-01

309

MALDI-TOF-MS analysis of sialylated glycans and glycopeptides using 4-chloro-?-cyanocinnamic acid matrix.  

PubMed

For MALDI analysis of glycans and glycopeptides, the choice of matrix is crucial in minimizing desialylation by mass spectrometric in-source and metastable decay. Here, we evaluated the potential of 4-chloro-?-cyanocinnamic acid (Cl-CCA) for MALDI-TOF-MS analysis of labile sialylated tryptic N-glycopeptides and released N- and O-glycans. Similar to DHB, but in contrast to CHCA, the Cl-CCA matrix allowed the analysis of sialylated N-glycans and glycopeptides in negative ion mode MALDI-TOF-MS. Dried droplet preparations of Cl-CCA provided microcrystals with a homogeneous spatial distribution and high shot-to-shot repeatability similar to CHCA, which simplified the automatic measurement and improved the resolution and mass accuracy. Interestingly, reflectron-positive ion mode analysis of 1-phenyl-3-methyl-5-pyrazolone (PMP)-labeled O-glycans with Cl-CCA revealed more complete profiles than with DHB and CHCA. In conclusion, we clearly demonstrate the high potential of this rationally designed matrix for glycomics and glycoproteomics. PMID:22589184

Selman, Maurice H J; Hoffmann, Marcus; Zauner, Gerhild; McDonnell, Liam A; Balog, Crina I A; Rapp, Erdmann; Deelder, André M; Wuhrer, Manfred

2012-05-01

310

MALDI-TOF MS and chemometric based identification of the Acinetobacter calcoaceticus-Acinetobacter baumannii complex species.  

PubMed

MALDI-TOF MS is becoming the technique of choice for rapid bacterial identification at species level in routine diagnostics. However, some drawbacks concerning the identification of closely related species such as those belonging to the Acinetobacter calcoaceticus-Acinetobacter baumannii (Acb) complex lead to high rates of misidentifications. In this work we successfully developed an approach that combines MALDI-TOF MS and chemometric tools to discriminate the six Acb complex species (A. baumannii, Acinetobacter nosocomialis, Acinetobacter pittii, A. calcoaceticus, genomic species "Close to 13TU" and genomic species "Between 1 and 3"). Mass spectra of 83 taxonomically well characterized clinical strains, reflecting the breadth of currently known phenetic diversity within the Acb complex, were achieved from intact cells and cell extracts and analyzed with hierarchical cluster analysis (HCA) and partial least squares discriminant analysis (PLSDA). This combined approach lead to 100% of correct species identification using mass spectra obtained from intact cells. Moreover, it was possible to discriminate two Acb complex species (genomic species "Close to 13TU" and genomic species "Between 1 and 3") not included in the MALDI Biotyper database. PMID:24877727

Sousa, Clara; Botelho, João; Silva, Liliana; Grosso, Filipa; Nemec, Alexandr; Lopes, João; Peixe, Luísa

2014-07-01

311

Rapid identification of Mycoplasma pulmonis isolated from laboratory mice and rats using matrix-assisted laser desorption ionization time-of-flight mass spectrometry.  

PubMed

Mycoplasma species identification is based on biochemical, immunological, and molecular methods that require several days for accurate identification. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) is a novel method for identification of bacteria and has recently been introduced into the clinical microbiology laboratory as a rapid and accurate technique. This method allows a characteristic mass spectral fingerprint to be obtained from whole inactivated mycoplasmal cells. In this study, we evaluated the performance of the MALDI-TOF MS for the identification of Mycoplasma by comparison with standard sequence analysis of 16S rRNA. We developed the first database of MALDI-TOF MS profiles of Mycoplasma species, containing Mycoplasma pulmonis, M. arthritidis, and M. neurolyticum, which are the most common pathogens in mice and/or rats, and species-specific spectra were recorded. Using the database, 6 clinical isolates were identified. Six tracheal swabs from 4 mice and 2 rats were cultured on PPLO agar for 4 to 7 days, and the colonies were directly applied to analyze the protein profiles. Five strains were identified as M. pulmonis, and 1 strain from a mouse was identified as M. neurolyticum (spectral scores were >2.00); the results were consistent with the results of the 16S rRNA gene sequence analysis (homologies>97.0%). These data indicate that MALDI-TOF MS can be used as a clearly rapid, accurate, and cost-effective method for the identification of M. pulmonis isolates, and this system may represent a serious alternative for clinical laboratories to identify Mycoplasma species. PMID:22498928

Goto, Kazuo; Yamamoto, Mikachi; Asahara, Miwa; Tamura, Takashi; Matsumura, Mitsuru; Hayashimoto, Nobuhito; Makimura, Koichi

2012-08-01

312

Quantitative determination of Piroxicam by TLC-MALDI TOF MS.  

PubMed

A quantitative thin-layer chromatography (TLC)-matrix-assisted laser desorption (MALDI) TOF mass spectrometry (MS) method for the determination of Piroxicam has been developed. Following preliminary experiments three different approaches to the incorporation of the internal standard (Tenoxicam) into the TLC plates were investigated. These were: (a) adding the internal standard to the mobile phase and pre-developing the plate, (b) coating the plate with internal standard by electrospraying prior to matrix application and finally, (c) mixing the internal standard into the matrix solution and electrospraying both. The most successful method was that where the internal standard was pre-developed over the plate. For this method linearity was observed over the range between 400 and 800ng of Piroxicam. The precision was found to be in the range of 1-9% R.S.D. from the average detected value (n = 5), dependent on the amount of analyte on the TLC plate. The proposed method was accurate with +/-2% deviation from the known amount of Piroxicam in the sample spot. PMID:15030877

Crecelius, Anna; Clench, Malcolm R; Richards, Don S; Parr, Vic

2004-04-01

313

Evaluation of MALDI-TOF mass spectrometry for identification of environmental yeasts and development of supplementary database.  

PubMed

Yeast identification using traditional methods which employ morphological, physiological, and biochemical characteristics can be considered a hard task as it requires experienced microbiologists and a rigorous control in culture conditions that could implicate in different outcomes. Considering clinical or industrial applications, the fast and accurate identification of microorganisms is a crescent demand. Hence, molecular biology approaches has been extensively used and, more recently, protein profiling using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has proved to be an even more efficient tool for taxonomic purposes. Nonetheless, concerning to mass spectrometry, data available for the differentiation of yeast species for industrial purpose is limited and reference databases commercially available comprise almost exclusively clinical microorganisms. In this context, studies focusing on environmental isolates are required to extend the existing databases. The development of a supplementary database and the assessment of a commercial database for taxonomic identifications of environmental yeast are the aims of this study. We challenge MALDI-TOF MS to create protein profiles for 845 yeast strains isolated from grape must and 67.7 % of the strains were successfully identified according to previously available manufacturer database. The remaining 32.3 % strains were not identified due to the absence of a reference spectrum. After matching the correct taxon for these strains by using molecular biology approaches, the spectra concerning the missing species were added in a supplementary database. This new library was able to accurately predict unidentified species at first instance by MALDI-TOF MS, proving it is a powerful tool for the identification of environmental yeasts. PMID:24687751

Agustini, Bruna Carla; Silva, Luciano Paulino; Bloch, Carlos; Bonfim, Tania M B; da Silva, Gildo Almeida

2014-06-01

314

Mass Spectrometry Primer  

NSDL National Science Digital Library

This website developed by Waters Corporation provides a brief primer on mass spectrometry which includes information on instrumentation, a discussion of mass accuracy, resolution, and LC-MS. As such the site should be a valuable resource for both students and faculty.

2011-06-13

315

Nevan Krogan: Mass Spectrometry  

NSDL National Science Digital Library

This lecture from the iBioSeminars project, presented by Nevan Krogan of the Department of Cellular and Molecular Pharmacology at UC-San Francisco, covers mass spectrometry and its application to molecular biology. Mass spectrometry is a powerful tool for elucidating the elemental composition of a sample or molecule. More recently, it has been used to characterize biological material, in particular proteins and protein complexes, in a variety of organisms. This lecture will review the underlying principles of how a mass spectrometer works, discuss up to date instrumentation that is presently being used in the biological research setting and provide specific examples of how mass spectrometry is being used to reveal functional insight into different biological systems. The video runs 27:36 and can be downloaded in a number of formats: QuickTime, MP4, M4V, and PPT. The video can also be streamed through YouTube or iTunes U.

Krogan, Nevan

2013-07-12

316

Metabolic fingerprinting using comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry.  

PubMed

Comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GC × GC-TOF-MS) is applied to the comparative metabolic fingerprinting of physiological fluids. Stable isotope-labeled internal standards plus norvaline serve as extraction standards and are added to the blanks, controls and patient samples prior to protein precipitation with methanol. The extracts are evaporated to complete dryness and derivatized in two steps using methoximation with methoxylamine hydrochloride (MeOx) and silylation with N-methyl-N-trimethylsily-trifluoroacetamide (MSTFA). Between derivatization steps a second internal standard containing odd-numbered, saturated straight chain fatty acids is added for quality control and to normalize retention time shifts. After GC × GC-TOF-MS analysis raw data are processed, aligned, and combined in one data matrix for subsequent statistical evaluation. Both a custom-made and the NIST 05 library are used to preliminarily identify significant metabolites. For verification purposes, commercial standards are run individually. Absolute quantification of selected metabolites is achieved by using a multi-point calibration curve and isotope-labeled internal standards. PMID:22131007

Almstetter, Martin F; Oefner, Peter J; Dettmer, Katja

2012-01-01

317

In Situ Identification of Plant-Invasive Bacteria with MALDI-TOF Mass Spectrometry  

PubMed Central

Rhizobia form a disparate collection of soil bacteria capable of reducing atmospheric nitrogen in symbiosis with legumes. The study of rhizobial populations in nature involves the collection of large numbers of nodules found on roots or stems of legumes, and the subsequent typing of nodule bacteria. To avoid the time-consuming steps of isolating and cultivating nodule bacteria prior to genotyping, a protocol of strain identification based on the comparison of MALDI-TOF MS spectra was established. In this procedure, plant nodules were considered as natural bioreactors that amplify clonal populations of nitrogen-fixing bacteroids. Following a simple isolation procedure, bacteroids were fingerprinted by analysing biomarker cellular proteins of 3 to 13 kDa using Matrix Assisted Laser Desorption/Ionization Time of Flight (MALDI-TOF) mass spectrometry. In total, bacteroids of more than 1,200 nodules collected from roots of three legumes of the Phaseoleae tribe (cowpea, soybean or siratro) were examined. Plants were inoculated with pure cultures of a slow-growing Bradyrhizobium japonicum strain G49, or either of two closely related and fast-growing Sinorhizobium fredii strains NGR234 and USDA257, or with mixed inoculants. In the fully automatic mode, correct identification of bacteroids was obtained for >97% of the nodules, and reached 100% with a minimal manual input in processing of spectra. These results showed that MALDI-TOF MS is a powerful tool for the identification of intracellular bacteria taken directly from plant tissues.

Pfluger, Valentin; Saad, Maged; Vogel, Guido; Tonolla, Mauro; Perret, Xavier

2012-01-01

318

Stimulation and release from neurons via a dual capillary collection device interfaced to mass spectrometry.  

PubMed

Neuropeptides are cell to cell signaling molecules that modulate a wide range of physiological processes. Neuropeptide release has been studied in sample sizes ranging from single cells and neuronal clusters, to defined brain nuclei and large brain regions. We have developed and optimized cell stimulation and collection approaches for the efficient measurement of neuropeptide release from neuronal samples using a dual capillary system. The defining feature is a capillary that contains octadecyl-modified silica nanoparticles on its inner wall to capture and extract releasates. This collection capillary is inserted into another capillary used to deliver solutions that chemically stimulate the cells, with solution flowing up the inner capillary to facilitate peptide collection. The efficiency of peptide collection was evaluated using six peptide standards mixed in physiological saline. The extracted peptides eluted from these capillaries were characterized via matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) with low femtomole detection limits. Using the capillary collection system in small custom-fabricated culturing chambers, individual cultured neurons and neuronal clusters from the model animal Aplysia californica were stimulated with distinct neuronal secretagogues and the releasates were collected and characterized using MALDI-TOF MS. PMID:24040641

Fan, Yi; Lee, Chang Young; Rubakhin, Stanislav S; Sweedler, Jonathan V

2013-11-01

319

Direct Analysis in Real Time Mass Spectrometry (DART-MS) Analysis of Skin Metabolome Changes in the Ultraviolet B-Induced Mice.  

PubMed

Ultraviolet (UV) radiation is a major environmental factor that leads to acute and chronic reactions in the human skin. UV exposure induces wrinkle formation, DNA damage, and generation of reactive oxygen species (ROS). Most mechanistic studies of skin physiology and pharmacology related with UV-irradiated skin have focused on proteins and their related gene expression or single- targeted small molecules. The present study identified and analyzed the alteration of skin metabolites following UVB irradiation and topical retinyl palmitate (RP, 5%) treatment in hairless mice using direct analysis in real time (DART) time-of-flight mass spectrometry (TOF-MS) with multivariate analysis. Under the negative ion mode, the DART ion source successfully ionized various fatty acids including palmitoleic and linolenic acid. From DART-TOF-MS fingerprints measured in positive mode, the prominent dehydrated ion peak (m/z: 369, M+H-H2O) of cholesterol was characterized in all three groups. In positive mode, the discrimination among three groups was much clearer than that in negative mode by using multivariate analysis of orthogonal partial-least squares-discriminant analysis (OPLS-DA). DART-TOF-MS can ionize various small organic molecules in living tissues and is an efficient alternative analytical tool for acquiring full chemical fingerprints from living tissues without requiring sample preparation. DART-MS measurement of skin tissue with multivariate analysis proved to be a powerful method to discriminate between experimental groups and to find biomarkers for various experiment models in skin dermatological research. PMID:24404338

Park, Hye Min; Kim, Hye Jin; Jang, Young Pyo; Kim, Sun Yeou

2013-11-01

320

Novel Approach for Differentiating Shigella Species and Escherichia coli by Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry  

PubMed Central

Shigella species are so closely related to Escherichia coli that routine matrix-assisted laser desorption/ionization–time of flight mass spectrometry (MALDI-TOF MS) cannot reliably differentiate them. Biochemical and serological methods are typically used to distinguish these species; however, “inactive” isolates of E. coli are biochemically very similar to Shigella species and thus pose a greater diagnostic challenge. We used ClinProTools (Bruker Daltonics) software to discover MALDI-TOF MS biomarker peaks and to generate classification models based on the genetic algorithm to differentiate between Shigella species and E. coli. Sixty-six Shigella spp. and 72 E. coli isolates were used to generate and test classification models, and the optimal models contained 15 biomarker peaks for genus-level classification and 12 peaks for species-level classification. We were able to identify 90% of E. coli and Shigella clinical isolates correctly to the species level. Only 3% of tested isolates were misidentified. This novel MALDI-TOF MS approach allows laboratories to streamline the identification of E. coli and Shigella species.

Khot, Prasanna D.

2013-01-01

321

Successful Identification of Clinical Dermatophyte and Neoscytalidium Species by Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry  

PubMed Central

Dermatophytes are keratinolytic fungi responsible for a wide variety of diseases of glabrous skin, nails, and hair. Their identification, currently based on morphological criteria, is hindered by intraspecies morphological variability and the atypical morphology of some clinical isolates. The aim of this study was to evaluate matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) as a routine tool for identifying dermatophyte and Neoscytalidium species, both of which cause dermatomycoses. We first developed a spectral database of 12 different species of common and unusual dermatophytes and two molds responsible for dermatomycoses (Neoscytalidium dimidiatum and N. dimidiatum var. hyalinum). We then prospectively tested the performance of the database on 381 clinical dermatophyte and Neoscytalidium isolates. Correct identification of the species was obtained for 331/360 dermatophytes (91.9%) and 18/21 Neoscytalidium isolates (85.7%). The results of MALDI-TOF MS and standard identification disagreed for only 2 isolates. These results suggest that MALDI-TOF MS could be a useful tool for routine and fast identification of dermatophytes and Neoscytalidium spp. in clinical mycology laboratories.

Alshawa, Kinda; Beretti, Jean-Luc; Lacroix, Claire; Feuilhade, Martine; Dauphin, Brunhilde; Quesne, Gilles; Hassouni, Noura; Nassif, Xavier

2012-01-01

322

What is new in clinical microbiology-microbial identification by MALDI-TOF mass spectrometry: a paper from the 2011 William Beaumont Hospital Symposium on molecular pathology.  

PubMed

Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) offers the possibility of accurate, rapid, inexpensive identification of bacteria, fungi, and mycobacteria isolated in clinical microbiology laboratories. The procedures for preanalytic processing of organisms and analysis by MALDI-TOF MS are technically simple and reproducible, and commercial databases and interpretive algorithms are available for the identification of a wide spectrum of clinically significant organisms. Although only limited work has been reported on the use of this technique to identify molds, perform strain typing, or determine antibiotic susceptibility results, these are fruitful areas of promising research. As experience is gained with MALDI-TOF MS, it is expected that the databases will be expanded to resolve many of the current inadequate identifications (eg, no identification, genus-level identification) and algorithms for potential misidentification will be developed. The current lack of Food and Drug Administration approval of any MALDI-TOF MS system for organism identification limits widespread use in the United States. PMID:22795961

Murray, Patrick R

2012-09-01

323

Use of Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry To Resolve Complex Clinical Cases of Patients with Recurrent Bacteremias  

PubMed Central

Matrix-assisted laser desorption–ionization time of flight mass spectrometry (MALDI-TOF MS) is a rapid and accurate method of identifying microorganisms. Throughout Europe, it is already in routine use but has not yet been widely implemented in the United States, pending FDA approval. Here, we describe two medically complex patients at a large tertiary-care academic medical center with recurring bacteremias caused by distinct but related species. Bacterial identifications were initially obtained using the Vitek-2 system with the GPI card for Enterococcus and the API system for staphylococci. Initial results misled clinicians as to the source and proper management of these patients. Retrospective investigation with MALDI-TOF MS clarified the diagnosis by identifying a single microorganism as the pathogen in each case. To our knowledge, this is one of the first reports in the United States demonstrating the use of MALDI-TOF MS to facilitate the clinical diagnosis in patients with recurrent bacteremias of unclear source.

Nori, Priya; Ostrowsky, Belinda; Dorokhova, Olena; Gialanella, Philip; Moy, Morgan; Muggia, Victoria; Grossberg, Robert; Kornblum, John; Lin, Ying

2013-01-01

324

Characterization of forced degradation products of ketorolac tromethamine using LC/ESI/Q/TOF/MS/MS and in silico toxicity prediction.  

PubMed

Ketorolac, a nonsteroidal anti-inflammatory drug, was subjected to forced degradation studies as per International Conference on Harmonization guidelines. A simple, rapid, precise, and accurate high-performance liquid chromatography combined with electrospray ionization quadrupole time-of-flight tandem mass spectrometry (LC/ESI/Q/TOF/MS/MS) method has been developed for the identification and structural characterization of stressed degradation products of ketorolac. The drug was found to degrade in hydrolytic (acidic, basic, and neutral), photolytic (acidic, basic, and neutral solution), and thermal conditions, whereas the solid form of the drug was found to be stable under photolytic conditions. The method has shown adequate separation of ketorolac tromethamine and its degradation products on a Grace Smart C-18 (250?mm?×?4.6?mm i.d., 5?µm) column using 20?mM ammonium formate (pH?=?3.2): acetonitrile as a mobile phase in gradient elution mode at a flow rate of 1.0?ml/min. A total of nine degradation products were identified and characterized by LC/ESI/MS/MS. The most probable mechanisms for the formation of degradation products have been proposed on the basis of a comparison of the fragmentation of the [M?+?H](+) ions of ketorolac and its degradation products. In silico toxicity of the drug and degradation products was investigated by using topkat and derek softwares. The method was validated in terms of specificity, linearity, accuracy, precision, and robustness as per International Conference on Harmonization guidelines. PMID:24809899

Kalariya, Pradipbhai D; Raju, B; Borkar, Roshan M; Namdev, Deepak; Gananadhamu, S; Nandekar, Prajwal P; Sangamwar, Abhay T; Srinivas, R

2014-05-01

325

UPLC Q-TOF/MS-Based Metabolic Profiling of Urine Reveals the Novel Antipyretic Mechanisms of Qingkailing Injection in a Rat Model of Yeast-Induced Pyrexia  

PubMed Central

Fever is one of the most common clinical symptoms of many diseases. Qingkailing (QKL) injection is widely used in China as a clinical emergency medicine due to its good antipyretic effects. It is a herbal formula which is composed by eight kinds of traditional Chinese medicines (TCM). As a kind of typical multiple constituents and multiple actions of TCM, it is very difficult to elaborate the antipyretic mechanism by conventional pharmacological method. Metabonomics technique provides beneficial tool for this challenge. In this study, an ultra performance liquid chromatography quadrupole time-of-flight mass spectrometry (UPLC Q-TOF/MS) metabonomics method was developed to explore the changing process of biochemical substances in rats of yeast-induced pyrexia. Partial least squares discriminate analysis (PLS-DA) was used to distinguish the normal control group, the pyrexia model group, and the pyrexia model group treated by QKL injection. The potential biomarkers related to pyrexia were confirmed and identified. MetPA was used to find the possible metabolic pathways. The results indicated that the antipyretic effect of QKL injection on yeast-induced pyrexia rats was performed by repairing the perturbed metabolism of amino acids.

Gao, Xiaoyan; Guo, Mingxing; Peng, Long; Zhao, Baosheng; Su, Jiankun; Liu, Haiyu; Zhang, Li; Bai, Xu; Qiao, Yanjiang

2013-01-01

326

Relative quantitation of glycosylation variants by stable isotope labeling of enzymatically released N-glycans using [12C]/[13C] aniline and ZIC-HILIC-ESI-TOF-MS.  

PubMed

Glycan reductive isotope labeling (GRIL) using [(12)C]- and [(13)C]-coded aniline was used for relative quantitation of N-glycans. In a first step, the labeling method by reductive amination was optimized for this reagent. It could be demonstrated that selecting aniline as limiting reactant and using the reductant in excess is critical for achieving high derivatization yields (over 95 %) and good reproducibility (relative standard deviations ?1-5 % for major and ?5-10 % for minor N-glycans). In a second step, zwitterionic-hydrophilic interaction liquid chromatography in capillary columns coupled to electrospray mass spectrometry with time-of-flight analyzer (?ZIC-HILIC-ESI-TOF-MS) was applied for the analysis of labeled N-glycans released from intact glycoproteins. Ovalbumin, bovine ?1-acid-glycoprotein and bovine fetuin were used as test glycoproteins to establish and evaluate the methodology. Excellent separation of isomeric N-glycans and reproducible quantitation via the extracted ion chromatograms indicate a great potential of the proposed methodology for glycoproteomic analysis and for reliable relative quantitation of glycosylation variants in biological samples. PMID:23846592

Giménez, Estela; Sanz-Nebot, Victòria; Rizzi, Andreas

2013-09-01

327

Simultaneous Quantitative and Qualitative Analysis of Flavonoids from Ultraviolet-B Radiation in Leaves and Roots of Scutellaria baicalensis Georgi Using LC-UV-ESI-Q/TOF/MS.  

PubMed

Scutellaria baicalensis Georgi is one of the most widely used traditional Chinese herbal medicines. It has been used for anti-inflammatory, anticancer, antibacterial activities, and so forth. Long-term enhanced ultraviolet-B (UV-B) radiation caused more effect on leaves than on roots of the plant. Liquid chromatography-ultraviolet detection coupled with electrospray ionization quadrupole time-of-flight mass spectrometry (LC-UV-ESI-Q/TOF/MS) method was applied for simultaneous quantitative and qualitative analysis of flavonoids in leaves and roots of S. baicalensis by enhanced UV-B radiation. Both low-intensity radiation and high-intensity radiation were not significantly increaseing the contents of baicalin, wogonoside, and wogonin in roots. However different intensity of radiation has different effects on several flavonoids in leaves. Both low-intensity radiation and high-intensity radiation had no significant effect on contents of baicalin and tectoridin in leaves; the content of scutellarin was significantly decreased by low-intensity radiation; chrysin was detected in low-intensity radiation and high-intensity radiation, and chrysin content is the highest in low-intensity radiation, but chrysin was not detected in control group. Different changes of different flavonoids under enhanced UV-B radiation indicate that induction on flavonoids is selective by enhanced UV-B radiation. PMID:24757579

Tang, Wen-Ting; Fang, Min-Feng; Liu, Xiao; Yue, Ming

2014-01-01

328

QSRR using evolved artificial neural network for 52 common pharmaceuticals and drugs of abuse in hair from UPLC-TOF-MS.  

PubMed

A quantitative structure-retention relationship (QSRR) study based on an artificial neural network (ANN) was carried out for the prediction of the ultra-performance liquid chromatography-Time-of-Flight mass spectrometry (UPLC-TOF-MS) retention time (RT) of a set of 52 pharmaceuticals and drugs of abuse in hair. The genetic algorithm was used as a variable selection tool. A partial least squares (PLS) method was used to select the best descriptors which were used as input neurons in neural network model. For choosing the best predictive model from among comparable models, square correlation coefficient R(2) for the whole set calculated based on leave-group-out predicted values of the training set and model-derived predicted values for the test set compounds is suggested to be a good criterion. Finally, to improve the results, structure-retention relationships were followed by a non-linear approach using artificial neural networks and consequently better results were obtained. This also demonstrates the advantages of ANN. PMID:21905247

Noorizadeh, Hadi; Farmany, Abbas; Narimani, Hojat; Noorizadeh, Mehrab

2013-05-01

329

Isolation and identification of antiplasmodial N-alkylamides from Spilanthes acmella flowers using centrifugal partition chromatography and ESI-IT-TOF-MS.  

PubMed

The development of new antiplasmodial drugs is of primary importance due to the growing problem of multi-drug resistance of malaria parasites. Spilanthes acmella, a plant traditionally used for the treatment of toothache, was targeted as a lead for its potential antiplasmodial activity. A systematic approach for investigating a suitable centrifugal partition chromatography (CPC) solvent system for N-alkylamides separation was reported. The partition behavior of three N-alkylamides has been studied using several biphasic solvent mixtures in search of an adequate CPC solvent system for this class of compounds. Major N-alkylamides in S. acmella were isolated from a methanolic crude extract of flowers by CPC with the solvent system heptanes-ethyl acetate-methanol-water (3:2:3:2, v/v/v/v). Four N-alkylamides were purified and the structures were illustrated by electrospray ionization-ion trap-time of flight-mass spectrometry (ESI-IT-TOF-MS), ¹H nuclear magnetic resonance (¹H NMR) and ¹³C nuclear magnetic resonance (¹³C NMR). The CPC fractions, which contained natural mixtures of phytochemicals, demonstrated significantly higher antiplasmodial activity compared to corresponding purified N-alkylamides, thus suggesting that interactions between these N-alkylamides may potentiate antiplasmodial bioactivity. PMID:21641879

Mbeunkui, Flaubert; Grace, Mary H; Lategan, Carmen; Smith, Peter J; Raskin, Ilya; Lila, Mary Ann

2011-07-01

330

Efficient preparative isolation and identification of walnut bioactive components using high-speed counter-current chromatography and LC-ESI-IT-TOF-MS.  

PubMed

Preparative isolation of complex mixtures of compounds from walnut polar extracts was established by a combination of high-speed counter-current chromatography (HSCCC) and electrospray ionization-ion trap-time of flight mass spectrometry (ESI-IT-TOF-MS). Compounds were isolated after a solvent optimisation selection based on solute distribution in a biphasic solvent system. Isolation was achieved through one or two successive HSCCC runs, and final purification on Sephadex LH-20. Isolated compounds included ellagitannins (1-11), gallic acid (12), dicarboxylic acid glucosides (13-15), hydrojuglone glucoside (16), catechin (17), procyanidin B2 (18), and megasterone glucosides (19-20). Praecoxin D (4) was isolated for the first time from walnut, while praecoxin A methyl ester (5) and glansreginin A n-butyl ester (14) are newly identified compounds. The purity and identity of isolated compounds were confirmed by NMR and HPLC-ESI-MS/MS. These results provided a foundation for in depth characterisation of walnut compounds and offered an efficient strategy for isolation of potentially health-relevant phytochemicals from walnuts. PMID:24731336

Grace, Mary H; Warlick, Charles W; Neff, Scott A; Lila, Mary Ann

2014-09-01

331

Application of nanoLC-ESI-TOF-MS for the metabolomic analysis of phenolic compounds from extra-virgin olive oil in treated colon-cancer cells.  

PubMed

Crude phenolic extracts (PE) have been obtained from naturally bearing Spanish extra-virgin olive oil (EVOO) showing different polyphenol families such as secoiridoids, phenolic alcohols, lignans, and flavones. EVOO-derived complex phenols (especially from the Arbequina variety olive) have been shown to suppress cell growth of SW480 and HT29 human colon adenocarcinoma cell lines. Inhibition of proliferation by EVOO-PE Arbequina variety extract was accompanied by apoptosis in both colon-cancer-cell lines and a limited G?M cell-cycle arrest in the case of SW480 cells. The metabolized compounds from EVOO-PE in culture medium and cytoplasm of both cell lines were analyzed using nano-liquid chromatography (nanoLC) coupled with electrospray ionization-time-of-flight-mass spectrometry (ESI-TOF-MS). The results showed many phenolic compounds and their metabolites both in the culture medium as well as in the cytoplasm. The main compounds identified from EVOO-PE were hydroxylated luteolin and decarboxymethyl oleuropein aglycone. PMID:22365054

Fernández-Arroyo, S; Gómez-Martínez, A; Rocamora-Reverte, L; Quirantes-Piné, R; Segura-Carretero, A; Fernández-Gutiérrez, A; Ferragut, J A

2012-04-01

332

UHPLC UHD Q-TOF MS/MS analysis of the impact of sulfur fumigation on the chemical profile of Codonopsis Radix (Dangshen).  

PubMed

Over recent decades sulfur fumigation has been becoming abused in processing some freshly harvested Chinese medicinal herbs, although it is questioned whether sulfur fumigation can result in changes in efficacy and safety of the herbs. One of the herbs commonly processed by sulfur fumigation is Codonopsis Radix (Dangshen). A report showed that lobetyolin content in sulfur-fumigated Dangshen was lower than in air-dried Dangshen. Whereas there is no investigation designed to compare the chemical profiles of the sulfur-fumigated Dangshen and the air-dried Dangshen. In the present study, a rapid and versatile ultra-high-performance liquid chromatography coupled with ultra-high resolution quadrupole time-of-flight mass spectrometry (UHPLC UHD Q-TOF MS/MS) method was developed for comprehensive analysis of the chemical profiles of sulfur-fumigated and air-dried Dangshen samples. Principal component analysis (PCA) and partial least squares-discriminant analysis (PLS-DA) demonstrated that there were significant chemical differences between sulfur-fumigated and air-dried Dangshen samples. Among the changed components, 57 compounds were identified, in which 15 sulfur-containing compounds were detected only in sulfur-fumigated samples. The established methods were successfully applied to discriminate sulfur-fumigated Dangshen among commercial samples. Whether the chemical changes caused by sulfur fumigation affect the clinical efficacy and safety of Dangshen needs to be further investigated. PMID:24286102

Ma, Xiao-qing; Leung, Alexander Kai Man; Chan, Chi Leung; Su, Tao; Li, Wei-dong; Li, Su-mei; Fong, David Wang Fun; Yu, Zhi-Ling

2014-01-21

333

Detection of sheep and goat milk adulterations by direct MALDI-TOF MS analysis of milk tryptic digests.  

PubMed

In dairy field, one of the most common frauds is the adulteration of higher value types of milk (sheep's and goat's) with milk of lower value (cow's milk). This illegal practice has an economic advantage for milk producers and poses a threat for consumers' health because of the presence of hidden allergens as, for example, cow milk proteins, in particular, ?(s1)-casein and ?-lactoglobulin. The urgent need of sensitive techniques to detect this kind of fraud brought to the development of chromatographic, immunoenzymatic, electrophoretic and mass spectrometric assays. In the current work, we present a fast, reproducible and sensitive method based on the direct matrix-assisted laser desorption/ionization-time-of-flight (MALDI-TOF) MS analysis of milk tryptic digests for the detection of milk adulteration by evaluating specie-specific markers in the peptide profiles. Several pure raw and commercial milk samples and binary mixtures containing cows' and goats', cows' and sheep's and goats' and sheep's milk (concentrations of each milk varied from 0% to 100%) were prepared, and tryptic digests were analyzed by MALDI-TOF MS. The use of the new MALDI matrix ?-cyano-4-chlorocinnamic acid allowed to detect cow and goat milk peptide markers up to 5% level of adulteration. Finally, from preliminary data, it seems that the strategy could be successfully applied also to detect similar adulterations in cheese samples. PMID:22972782

Calvano, Cosima Damiana; De Ceglie, Cristina; Monopoli, Antonio; Zambonin, Carlo Giorgio

2012-09-01

334

Screening and characterization of natural antioxidants in four Glycyrrhiza species by liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry.  

PubMed

Licorice, derived from the dried roots and rhizomes of several species of genus Glycyrrhiza L. (Leguminosae family), has been traditionally used in herbal medicine for over 4000 years. In recent years, the interest in antioxidative constituents in licorice has greatly increased. In this work, a new method based on 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) spiking test combined with HPLC coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry (Q-TOF MS/MS) analysis was developed to screen and identify the antioxidants in licorice. The results of the method validation indicated that the developed method was reliable and repeatable. Compared with DPPH on-line method, the HPLC-Q-TOF MS/MS method combined with DPPH spiking test offered much higher sensitivity and resolution. Using this method, 35 radical scavengers were screened from four Glycyrrhiza species (G. inflata, G. glabra, G. pallidiflora and G. uralensis), and 21 of them were unambiguously or tentatively identified by HPLC-Q-TOF MS/MS. Among the 21 identified flavonoids, 10 compounds had been reported to possess antioxidative activities in the previous studies, and the radical scavenging activities of the other 11 compounds were reported for the first time. The effects of six purified flavonoids on DPPH radical and lipid peroxidation were evaluated for validation of the developed method. The results indicated that HPLC-Q-TOF MS/MS coupled with DPPH treatment is an efficient and powerful method to discover the potential antioxidative compounds from the complex natural product mixtures. In this study, the identified components with free radical scavenging activity, would help to explain the therapeutic benefit of licorice in the treatment of human disease associated with oxidative stress. PMID:21968349

Li, Yan-Jing; Chen, Jun; Li, Ying; Li, Qin; Zheng, Yun-Feng; Fu, Yu; Li, Ping

2011-11-11

335

Rapid, sensitive, and validated UPLC/Q-TOF-MS method for quantitative determination of vasicine in Adhatoda vasica and its in vitro culture  

PubMed Central

Background: Adhatoda vasica a perennial herb has been used in Ayurvedic and Unani system of medicines since last 2000 years and has been employed for the treatment of respiratory tract ailments. Objective: To develop and validate new, rapid, and highly sensitive high throughput ultra-performance liquid chromatography/quadrupole-time-of-flight mass-spectrometry (UPLC/Q-TOF-MS) method for the quantitative estimation of vasicine in the leaves and to establish in vitro cultures of Adhatoda vasica for production of vasicine. Materials and Methods: The chromatographic separation was achieved on a Waters ACQUITY UPLC™ BEH C8 (100.0 × 2.1 mm; 1.7 ?m) column packing using isocratic mobile phase consisting of acetonitrile: 20 mM ammonium acetate (90:10; v/v) in a multiple reactions monitoring mode using the transitions m/z 189.09 ? 171.08 for vasicine. Results: The vasicine was eluted at 2.58 ± 0.05 min and established a dynamic range of linearity over the concentration range of 1-1000 ng/ml (r2 = 0.999 ± 0.0005). The lower limit of detection and quantification was 0.68 and 1.0 ng/ml, respectively. There was no significant difference observed in the content of vasicine (0.92-1.04%w/w) among the eleven samples collected from different locations of India. The in vitro cultures developed showed that addition of extra 28 mM KNO3 and 100 mM NaCl in MS medium supplemented with 2,4-dichlorophenoxyacetic acid (2,4-D) + benzyladenine (BA) + indole acetic acid (IAA) (1 ppm each) produces faster biomass and higher amount of quinazoline alkaloids. Conclusion: Rapid, efficient, and sensitive UPLC/Q-TOF-MS method was developed for the estimation of vasicine and an efficient protocol for development of in vitro cultures was proposed, which can be used at large scale for industrial production of vasicine using bioreactors.

Madhukar, Garg; Tamboli, Ennus Tajuddin; Rabea, Parveen; Ansari, S. H.; Abdin, M. Z.; Sayeed, Ahmad

2014-01-01

336

Sensitive high-resolution analysis of biological molecules by capillary zone electrophoresis coupled with reflecting time-of-flight mass spectrometry.  

PubMed

Off-line and on-line capillary zone electrophoresis-electrospray ionization time-of-flight mass spectrometry (CZE-ESI-TOF-MS) experiments were conducted using uncoated fused-silica capillaries coupled to a reflecting TOF mass spectrometer via a gold-coated sheathless interface. Off-line and on-line experiments were performed on standard mixtures of proteins and peptides. Samples collected off-line electrokinetically in plastic vials were analyzed by standard ESI-TOF-MS at the pmol level. Sheathless CZE-ESI-TOF-MS was first simulated in an off-line experiment, using a test bench, in order to select a suitable running electrolyte, to find the optimal electrospray potential, and also to test the gold-coated capillary tips. This enabled an ease of transition to on-line measurements. On-line CZE-ESI-TOF-MS measurements of the total ion electropherogram (TIE) and of selected ion electropherograms (SIE) on peptide mixtures demonstrated fmol-level sensitivity, with S/N values of 250-400 on raw data (TIE mode) and of 30-760 (SIE mode). The use of reflecting TOF-MS afforded mass resolution values R>6000 (m/delta(m)(FVHM)) and enabled isotopic resolution of peptide components as well as mass accuracy in the 10 ppm range. These results were comparable with values observed with the usual ESI source on the same mass spectrometer, and thus demonstrated no loss in spectral quality from using the sheathless CE interface. On-line CE separation efficiency was equivalent to that obtained off-line for the separation of a peptide mixture, with N=35000-87000 theoretical plates. Separations of standard proteins yielded equivalent mass spectral resolution and accuracy with separation efficiencies of N=2800-5500 and S/N values of 110-225 on raw data. The gold-coated sheathless CE-ESI interface was found to be relatively easy to prepare with the use of gold vapour deposition. The interface produced a stable electrospray for extended periods of time and was found to be robust and reliable. PMID:9583938

McComb, M E; Krutchinsky, A N; Ens, W; Standing, K G; Perreault, H

1998-03-20

337

Nanopore Mass Spectrometry  

NASA Astrophysics Data System (ADS)

We describe a concept for single-DNA analysis called nanopore mass spectrometry, which seeks to combine the benefits of nanopores with the speed, sensitivity, and robustness of single base detection by mass spectrometry. The basic idea is to cleave the individual nucleotides from a DNA polymer as they transit a nanopore in sequence, and to identify each one by determining its charge-to-mass ratio in a mass spectrometer. We describe how nanopore mass spectrometry can addresse the challenges faced by other nanopore-based DNA analysis approaches. We also describe the design, construction, and testing of a prototype instrument that interfaces a nanopore ion source with a quadrupole mass filter and a single ion detector. We are using this new instrument to test the key scientific questions bearing on our analysis strategy: 1) Can DNA nucleotides be reliably transferred from their native liquid phase into the vacuum environment of a mass spectrometer? 2) Can nucleotides be detected with near 100% efficiency? 3) Can DNA polymers be controllably cleaved to isolate ionized bases or nucleotides in the mass spectrometer?

Stein, Derek; Bush, Joseph; Mihovilovic, Mirna; Maulbetsch, William; Moon, Wooyoung; Bazemore-Walker, Carthene; Weber, Peter

2012-02-01

338

Conceptual Study on New Isotope Analysis Technique with Resonance Ionization Mass Spectrometry Using Inductively Coupled Plasma as an Atomic Source (ICP-RIMS)  

NASA Astrophysics Data System (ADS)

We have proposed the novel isotope analysis technique with Resonance Ionization Mass Spectrometry using Inductively Coupled Plasma as an atomic source (ICP-RIMS). Each component of ICP-RIMS is conceptually designed. We conclude that the orthogonal acceleration time-of-flight mass spectrometer (oa-TOF-MS) driven by a high-repetition-rate pulsed laser would be suitable system for ICP-RIMS. We, additionally, suggest that the first vacuum stage of the vacuum interface, which is between the sampling and skimmer cones, is desired to maintain as low pressure as possible in order to suppress the Doppler broadening and to skim the supersonic jet effectively.

Watanabe, K.; Higuchi, Y.; Tomita, H.; Kawarabayashi, J.; Uritani, A.; Iguchi, T.

2009-03-01

339

Conceptual Study on New Isotope Analysis Technique with Resonance Ionization Mass Spectrometry Using Inductively Coupled Plasma as an Atomic Source (ICP-RIMS)  

SciTech Connect

We have proposed the novel isotope analysis technique with Resonance Ionization Mass Spectrometry using Inductively Coupled Plasma as an atomic source (ICP-RIMS). Each component of ICP-RIMS is conceptually designed. We conclude that the orthogonal acceleration time-of-flight mass spectrometer (oa-TOF-MS) driven by a high-repetition-rate pulsed laser would be suitable system for ICP-RIMS. We, additionally, suggest that the first vacuum stage of the vacuum interface, which is between the sampling and skimmer cones, is desired to maintain as low pressure as possible in order to suppress the Doppler broadening and to skim the supersonic jet effectively.

Watanabe, K.; Uritani, A. [Department of Materials, Physics and Energy Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8603 (Japan); Higuchi, Y.; Tomita, H.; Kawarabayashi, J.; Iguchi, T. [Department of Quantum Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8603 (Japan)

2009-03-17

340

Detection of Large Ions in Time-of-Flight Mass Spectrometry: Effects of Ion Mass and Acceleration Voltage on Microchannel Plate Detector Response  

NASA Astrophysics Data System (ADS)

In time-of-flight mass spectrometry (TOF-MS), ion detection is typically accomplished by the generation and amplification of secondary electrons produced by ions colliding with a microchannel plate (MCP) detector. Here, the response of an MCP detector as a function of ion mass and acceleration voltage is characterized, for singly charged peptide/protein ions ranging from 1 to 290 kDa in mass, and for acceleration voltages from 5 to 25 kV. A nondestructive inductive charge detector (ICD) employed in parallel with MCP detection provides a reliable reference signal to allow accurate calibration of the MCP response. MCP detection efficiencies were very close to unity for smaller ions at high acceleration voltages (e.g., angiotensin, 1046.5 Da, at 25 kV acceleration voltage), but decreased to ~11% for the largest ions examined (immunoglobulin G (IgG) dimer, 290 kDa) even at the highest acceleration voltage employed (25 kV). The secondary electron yield ? (average number of electrons produced per ion collision) is found to be proportional to mv3.1 (m: ion mass, v: ion velocity) over the entire mass range examined, and inversely proportional to the square root of m in TOF-MS analysis. The results indicate that although MCP detectors indeed offer superlative performance in the detection of smaller peptide/protein species, their performance does fall off substantially for larger proteins, particularly under conditions of low acceleration voltage.

Liu, Ranran; Li, Qiyao; Smith, Lloyd M.

2014-05-01

341

Comparison of low molecular weight glutenin subunits identified by SDS-PAGE, 2-DE, MALDI-TOF-MS and PCR in common wheat  

PubMed Central

Background Low-molecular-weight glutenin subunits (LMW-GS) play a crucial role in determining end-use quality of common wheat by influencing the viscoelastic properties of dough. Four different methods - sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), two-dimensional gel electrophoresis (2-DE, IEF × SDS-PAGE), matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and polymerase chain reaction (PCR), were used to characterize the LMW-GS composition in 103 cultivars from 12 countries. Results At the Glu-A3 locus, all seven alleles could be reliably identified by 2-DE and PCR. However, the alleles Glu-A3e and Glu-A3d could not be routinely distinguished from Glu-A3f and Glu-A3g, respectively, based on SDS-PAGE, and the allele Glu-A3a could not be differentiated from Glu-A3c by MALDI-TOF-MS. At the Glu-B3 locus, alleles Glu-B3a, Glu-B3b, Glu-B3c, Glu-B3g, Glu-B3h and Glu-B3j could be clearly identified by all four methods, whereas Glu-B3ab, Glu-B3ac, Glu-B3ad could only be identified by the 2-DE method. At the Glu-D3 locus, allelic identification was problematic for the electrophoresis based methods and PCR. MALDI-TOF-MS has the potential to reliably identify the Glu-D3 alleles. Conclusions PCR is the simplest, most accurate, lowest cost, and therefore recommended method for identification of Glu-A3 and Glu-B3 alleles in breeding programs. A combination of methods was required to identify certain alleles, and would be especially useful when characterizing new alleles. A standard set of 30 cultivars for use in future studies was chosen to represent all LMW-GS allelic variants in the collection. Among them, Chinese Spring, Opata 85, Seri 82 and Pavon 76 were recommended as a core set for use in SDS-PAGE gels. Glu-D3c and Glu-D3e are the same allele. Two new alleles, namely, Glu-D3m in cultivar Darius, and Glu-D3n in Fengmai 27, were identified by 2-DE. Utilization of the suggested standard cultivar set, seed of which is available from the CIMMYT and INRA Clermont-Ferrand germplasm collections, should also promote information sharing in the identification of individual LMW-GS and thus provide useful information for quality improvement in common wheat.

2010-01-01

342

High-throughput ultra-performance liquid chromatography-mass spectrometry characterization of metabolites guided by a bioinformatics program.  

PubMed

Metabolite profiling in biomarker discovery research requires new data preprocessing approaches to correlate specific metabolites to their biological origin. Mass spectrometry-based metabolomics often results in the observation of hundreds to thousands of features that are differentially regulated in biosamples. Extracting biomedical information from large metabolomic datasets by multivariate data analysis is of considerable complexity. Therefore, more efficient and optimized metabolomics data processing technologies are needed to improve MS applications in biomarker discovery. Here we use a sensitive ultra-performance LC-ESI/quadrupole-TOF high-definition mass spectrometry (UPLC-ESI-Q-TOF-MS) approach, in negative ion mode, to characterize metabolites. XCMS online analysis was used which incorporates novel nonlinear retention time alignment, matched filtration, peak detection, and peak matching. XCMS software can facilitate prioritization of the data and greatly increases the probability of identifying metabolites causally related to the phenotype of interest. 26 urinary differential metabolites contributing to the complete separation of HCC patients from matched healthy controls were identified involving the key metabolic pathways including tyrosine metabolism, glutathione metabolism, phenylalanine metabolism, ascorbate and aldarate metabolism, and arginine and proline metabolism. It demonstrates that high-throughput UPLC-ESI-Q-TOF-MS metabonomics combined with the proposed bioinformatic approach (based on XCMS) are pivotal to elucidate the developing biomarkers and physiological mechanism of disease in a clinical setting. PMID:23821129

Zhang, Ai-hua; Wang, Ping; Sun, Hui; Yan, Guang-li; Han, Ying; Wang, Xi-jun

2013-09-01

343

Mass Spectrometry Contamination from Tinuvin 770, a Common Additive in Laboratory Plastics  

PubMed Central

The superior sensitivity of current mass spectrometers makes them prone to contamination issues, which can have deleterious effects on sample analysis. Here, bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate (marketed under the name Tinuvin 770) is identified as a major contaminant in applications using liquid chromatography coupled with mass spectrometry (LC-MS). Tinuvin 770 is often added to laboratory and medical plastics as a UV stabilizer. One particular lot of microcentrifuge tubes was found to have an excess of this compound that would leach into samples and drastically interfere with LC-MS data acquisition. Further analysis found that Tinuvin 770 readily leached into polar and nonpolar solvents from the contaminated tube lot. Efforts to remove Tinuvin 770 from contaminated samples were unsuccessful. A prescreening method using MALDI-TOF MS is presented to prevent system contamination and sample loss.

Schauer, Kevin L.; Broccardo, Carolyn J.; Webb, Kimberly M.; Covey, Paul A.; Prenni, Jessica E.

2013-01-01

344

Laser Time-of-Flight Mass Spectrometry for Future In Situ Planetary Missions  

NASA Technical Reports Server (NTRS)

Laser desorption/ionization time-of-flight mass spectrometry (LD-TOF-MS) is a versatile, low-complexity instrument class that holds significant promise for future landed in situ planetary missions that emphasize compositional analysis of surface materials. Here we describe a 5kg-class instrument that is capable of detecting and analyzing a variety of analytes directly from rock or ice samples. Through laboratory studies of a suite of representative samples, we show that detection and analysis of key mineral composition, small organics, and particularly, higher molecular weight organics are well suited to this instrument design. A mass range exceeding 100,000 Da has recently been demonstrated. We describe recent efforts in instrument prototype development and future directions that will enhance our analytical capabilities targeting organic mixtures on primitive and icy bodies. We present results on a series of standards, simulated mixtures, and meteoritic samples.

Getty, S. A.; Brinckerhoff, W. B.; Cornish, T.; Ecelberger, S. A.; Li, X.; Floyd, M. A. Merrill; Chanover, N.; Uckert, K.; Voelz, D.; Xiao, X.; Tawalbeh, R.; Glenar, D.; Elsila, J. E.; Callahan, M.

2012-01-01

345

Analytical mass spectrometry. Abstracts  

SciTech Connect

This 43rd Annual Summer Symposium on Analytical Chemistry was held July 24--27, 1990 at Oak Ridge, TN and contained sessions on the following topics: Fundamentals of Analytical Mass Spectrometry (MS), MS in the National Laboratories, Lasers and Fourier Transform Methods, Future of MS, New Ionization and LC/MS Methods, and an extra session. (WET)

Not Available

1990-12-31

346

Analytical mass spectrometry  

SciTech Connect

This 43rd Annual Summer Symposium on Analytical Chemistry was held July 24--27, 1990 at Oak Ridge, TN and contained sessions on the following topics: Fundamentals of Analytical Mass Spectrometry (MS), MS in the National Laboratories, Lasers and Fourier Transform Methods, Future of MS, New Ionization and LC/MS Methods, and an extra session. (WET)

Not Available

1990-01-01

347

Glow discharge mass spectrometry  

Microsoft Academic Search

Over the past twenty years or so, glow discharge mass spectrometry (GDMS) has become the industry standard for the analysis of trace elements in metals and semiconductors. A review of its history is followed by a picture of the present situation and a look to where the future may lie. Applications are summarised, including the ability of GDMS to offer depth-resolved

Volker Hoffmann; Martin Kasik; Peter K. Robinson; Cornel Venzago

2005-01-01

348

[Search of streptomycin-resistant bacteria in creek water and application of MALDI-TOF MS to grouping of the isolated bacteria].  

PubMed

A search of streptomycin-resistant bacteria was carried out using ten creek water samples collected in Saga prefecture by spreading the sample water on an R2A medium containing 10 microg/ml of streptomycin. It was clarified that such streptomycin-resistant bacteria as Bacillus, Novosphigobium, Sphingopyxis and Oceanobacillus were distributed in the creek water. Further, 60% of the isolates didn't form an inhibitory zone by the application of 700 microg/ml streptomycin solution in the cup method assay. Further, the effectiveness of the MALDI-TOF MS analysis for the grouping of the isolates was examined. The discriminating ability of MALDI-TOF MS analysis was higher than that of RFLP analysis and it was almost equal to that of sequence analysis using 16S rDNA. Considering the high-throughput ability of the MALDI-TOF MS instrument, MALDI-TOF mass spectral identification of bacteria will be a powerful method in the construction of a MALDI-TOF mass spectra database. PMID:18350749

Ichiki, Yayoi; Aoki, Tomohiro; Takashima, Yasuto; Tamura, Hiroto; Teramoto, Kanae; Sato, Hiroaki; Arashidani, Keiichi; Yoshikawa, Hiromichi

2008-03-01

349

Chaperonin GroEL a Brucella immunodominant antigen identified using Nanobody and MALDI-TOF-MS technologies.  

PubMed

The deployment of today's antibodies that are able to distinguish Brucella from the closely similar pathogens, such as Yersinia, is still considered a great challenge since both pathogens share identical LPS (lipopolysaccharide) O-ring epitopes. In addition, because of the great impact of Brucella on health and economy in many countries including Syria, much effort is going to the development of next generation vaccines, mainly on the identification of new immunogenic proteins of this pathogen. In this context, Brucella-specific nanobodies (Nbs), camel genetic engineered heavy-chain antibody fragments, could be of great value. Previously, a large Nb library was constructed from a camel immunized with heat-killed Brucella. Phage display panning of this 'immune' library with Brucella total lysate resulted in a remarkable fast enrichment for a Nb referred to as NbBruc02. In the present work, we investigated the main characteristics of this Nb that can efficiently distinguish under well-defined conditions the Brucella from other bacteria including Yersinia. NbBruc02 showed a strong and specific interaction with its antigen within the crude lysate as tested by a surface plasmon resonance (SPR) biosensor and it was also able to pull down its cognate antigen from such lysate by immuno-capturing. Using matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS), NbBruc02 specific antigen was identified as chaperonin GroEL, also known as heat shock protein of 60 kDa (HSP-60), which represents a Brucella immunodominant antigen responsible of maintaining proteins folding during stress conditions. Interestingly, the antigen recognition by NbBruc02 was found to be affected by the state of GroEL folding. Thus, the Nb technology applied in the field of infectious diseases, e.g. brucellosis, yields two outcomes: (1) it generates specific binders that can be used for diagnosis, and perhaps treatment, and (2) it identifies the immunogenic candidate antigens for developing vaccines. PMID:22472910

Abbady, A Q; Al-Daoude, A; Al-Mariri, A; Zarkawi, M; Muyldermans, S

2012-05-15

350

UPLC-Q-TOF/MS coupled with multivariate statistical analysis as a powerful technique for rapidly exploring potential chemical markers to differentiate between radix paeoniae alba and radix paeoniae rubra.  

PubMed

To explore rapidly the potential chemical markers for differentiating Radix Paeoniae Alba and Radix Paeoniae Rubra, a method is proposed based on ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF/MS) coupled with multivariate statistical analysis. Batches of commercial samples were analyzed by UPLC-Q-TOF/MS. The datasets of t(R)-m/z pair, ion intensities and sample codes were further processed with orthogonal partial least squared discriminant analysis (OPLS-DA) to compare holistically the difference between these two kinds of samples. Then statistics were used to generate an S-plot, in which the variables (t(R)-m/z pair) contributing most to the difference were clearly depicted as points at the two ends of "S", and the components correlated to these ions should be regarded as the chemical markers. The identities of the most changed markers can be identified by comparing the mass/UV spectra and retention times with those of reference compounds and/or tentatively assigned by matching empirical molecular formulae with those of known compounds published in the literature. Using this proposed approach, albflorin, paeoniflorin, oxypaeoniflorin, benzoylpaeoniflorin, galloylalbiflorin and paeoniflorigenone were found to be the differentiating components for discrimination of Radix Paeoniae Alba and Radix Paeoniae Rubra. Moreover, paeoniflorin sulfonate and its isomer, isomaltopaeoniflorin sulfonate, were found to be the characteristic markers for all Radix Paeoniae Alba samples that were processed by sulfurdioxide gas fumigation. The results suggested that this newly established approach could be used to explore rapidly the potential chemical markers for herbs with similar chemical characteristics. PMID:23738461

Luo, Nian-Cui; Ding, Wen; Wu, Jing; Qian, Da-Wei; Li, Zhen-Hao; Qian, Ye-Fei; Guo, Jian-Ming; Duan, Jin-Ao

2013-04-01

351

Multiple-reflection time-of-flight mass spectrometry for in situ applications  

NASA Astrophysics Data System (ADS)

Multiple-reflection time-of-flight mass spectrometers (MR-TOF-MS) have recently been installed at different low-energy radioactive ion beam facilities. They are used as isobar separators with high ion capacity and as mass spectrometers with high mass resolving power and accuracy for short-lived nuclei. Furthermore, MR-TOF-MS have a huge potential for applications in other fields, such as chemistry, biology, medicine, space science, and homeland security. The development, commissioning and results of an MR-TOF-MS is presented, which serves as proof-of-principle to show that very high mass resolving powers (˜105) can be achieved in a compact device (length ˜30 cm). Based on this work, an MR-TOF-MS for in situ application has been designed. For the first time, this device combines very high mass resolving power (>105), mobility, and an atmospheric pressure inlet in one instrument. It will enable in situ measurements without sample preparation at very high mass accuracy. Envisaged applications of this mobile MR-TOF-MS are discussed.

Dickel, T.; Plaß, W. R.; Lang, J.; Ebert, J.; Geissel, H.; Haettner, E.; Jesch, C.; Lippert, W.; Petrick, M.; Scheidenberger, C.; Yavor, M. I.

2013-12-01

352

A rapid MALDI-TOF mass spectrometry workflow for Drosophila melanogaster differential neuropeptidomics  

PubMed Central

Background Neuropeptides are a diverse category of signaling molecules in the nervous system regulating a variety of processes including food intake, social behavior, circadian rhythms, learning, and memory. Both the identification and functional characterization of specific neuropeptides are ongoing fields of research. Matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) analysis of nervous tissues from a variety of organisms allows direct detection and identification of neuropeptides. Here, we demonstrate an analysis workflow that allows for the detection of differences in specific neuropeptides amongst a variety of neuropeptides being simultaneously measured. For sample preparation, we describe a straight-forward and rapid (minutes) method where individual adult Drosophila melanogaster brains are analyzed. Using a MATLAB-based data analysis workflow, also compatible with MALDI-TOF mass spectra obtained from other sample preparations and instrumentation, we demonstrate how changes in neuropeptides levels can be detected with this method. Results Over fifty isotopically resolved ion signals in the peptide mass range are reproducibly observed across experiments. MALDI-TOF MS profile spectra were used to statistically identify distinct relative differences in organ-wide endogenous levels of detected neuropeptides between biological conditions. In particular, three distinct levels of a particular neuropeptide, pigment dispersing factor, were detected by comparing groups of preprocessed spectra obtained from individual brains across three different D. melanogaster strains, each of which express different amounts of this neuropeptide. Using the same sample preparation, MALDI-TOF/TOF tandem mass spectrometry confirmed that at least 14 ion signals observed across experiments are indeed neuropeptides. Among the identified neuropeptides were three products of the neuropeptide-like precursor 1 gene previously not identified in the literature. Conclusions Using MALDI-TOF MS and preprocessing/statistical analysis, changes in relative levels of a particular neuropeptide in D. melanogaster tissue can be statistically detected amongst a variety of neuropeptides. While the data analysis methods should be compatible with other sample preparations, the presented sample preparation method was sufficient to identify previously unconfirmed D. melanogaster neuropeptides.

2013-01-01

353

Perceiving the chemical language of Gram-negative bacteria: listening by high-resolution mass spectrometry.  

PubMed

Gram-negative bacteria use N-acylhomoserine lactones (AHLs) as their command language to coordinate population behavior during invasion and colonization of higher organisms. Although many different bacterial bioreporters are available for AHLs monitoring, in which a phenotypic response, e.g. bioluminescence, violacin production, and ?-galactosidase activity, is exploited, mass spectrometry (MS) is the most versatile detector for rapid analysis of AHLs in complex microbial samples, with or without prior separation steps. In this paper we critically review recent advances in the application of high-resolution MS to analysis of the quorum sensing (QS) signaling molecules used by Gram-negative bacteria, with much emphasis on AHLs. A critical review of the use of bioreporters in the study of AHLs is followed by a short methodological survey of the capabilities of high-resolution mass spectrometry (HRMS), including Fourier-transform ion cyclotron resonance (FTICR) MS and quadrupole time-of-flight (qTOF) MS. Use of infusion electrospray ultrahigh-resolution FTICR MS (12 Tesla) enables accurate mass measurements for determination of the elemental formulas of AHLs in Acidovorax sp. N35 and Burkholderia ubonensis AB030584. Results obtained by coupling liquid chromatography with a hybrid quadrupole linear ion trap-FTICR mass spectrometer (LC-LTQ-FTICRMS, 7-T) for characterization of acylated homoserine lactones in the human pathogen Pseudomonas aeruginosa are presented. UPLC-ESI-qTOF MS has also proved to be suitable for identification of 3O-C(10)HSL in Pseudomonas putida IsoF cell culture supernatant. Aspects of sample preparation and the avoidance of analytical pitfalls are also emphasized. PMID:22986985

Cataldi, Tommaso R I; Bianco, Giuliana; Fonseca, Juliano; Schmitt-Kopplin, Philippe

2013-01-01

354

Immunocytochemical and molecular data guide peptide identification by mass spectrometry: orcokinin and orcomyotropin-related peptides in the stomatogastric nervous system of several crustacean species.  

PubMed

In order to identify new orcokinin and orcomyotropin-related peptides in crustaceans, molecular and immunocytochemical data were combined with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). In the crayfish Procambarus clarkii, four orcokinins and an orcomyotropin-related peptide are present on the precursor. Because these peptides are highly conserved, we assumed that other species have an identical number of peptides. To identify the peptides, immunocytochemistry was used to localize the regions of the stomatogastric nervous system in which orcokinins are predominantly present. One of the regions predominantly containing orcokinins was a previously undescribed olive-shaped neuropil region within the commissural ganglia of the lobsters Homarus americanus and Homarus gammarus. MALDI-TOF MS on these regions identified peptide masses that always occur together with the known orcokinins. Seven peptide ions occurred together in the peptide massspectra of the lobsters. Mass spectrometric fragmentation by MALDI-MS post-source decay (PSD) and electrospray ionization quadrupole time-of-flight mass spectrometry (ESI Q-TOF MS) collision-induced dissociation (CID) were used in the identification of six of these masses, either as orcokinins or as orcomyotropin-related peptides and revealed three hitherto unknown peptide variants, two of which are [His13]-orcokinin ([M+H]+ = 1540.8 Da) and an orcomyotropin-related peptide FDAFTTGFGHN ([M+H]+ = 1213.5 Da). The mass of the third previously unknown orcokinin variant corresponded to that of an identified orcokinin, but PSD fragmentation did not support the suggested amino acid sequence. CID analysis allowed partial de novo sequencing of this peptide. In the crab Cancer pagurus, five orcokinins and an orcomyotropin-related peptide were unambigously identified, including the previously unknown peptide variant [Ser9-Val13]-orcokinin ([M+H]+ = 1532.8 Da). PMID:14528921

Skiebe, P; Dreger, M; Börner, J; Meseke, M; Weckwerth, W

2003-07-01

355

Comparative study of laser induced breakdown spectroscopy and mass spectrometry for the analysis of cultural heritage materials  

NASA Astrophysics Data System (ADS)

Analysis by laser-induced breakdown spectroscopy (LIBS) is compared, on the basis of a hybrid experimental set-up, with laser ablation time-of-flight mass spectrometry (LA-TOF-MS) for the characterization of materials relevant to cultural heritage. The present study focuses on the analysis of selected paint materials such as lithopone, a white inorganic pigment, and two synthetic organic paint formulations, lemon yellow and phthalocyanine blue. Optical emission spectra, obtained by LIBS, lead to rapid, straightforward identification of the elemental content of the paint samples while mass spectra yield, additionally to elemental analysis, complementary isotopic analysis and, more importantly, enable detection of molecules and molecular fragments, permitting a more complete structural and compositional characterization of composite materials. Mass spectra were recorded either simultaneously with the optical emission ones, or sequentially. The latter was preferred for materials having significantly lower fluence threshold for desorption/ionization relative to plasma formation resulting to optimum mass resolution and minimal surface damage. In all, the results of this study demonstrate the advantages of instrumentally complementing LIBS with TOF-MS in relation to applications in cultural heritage materials analysis, with exciting prospects when laser ablation sampling can be carried out under ambient atmosphere.

Kokkinaki, O.; Mihesan, C.; Velegrakis, M.; Anglos, D.

2013-07-01

356

Mass Spectrometry and Glycomics  

PubMed Central

Abstract Glycosylation defines the adhesive properties of animal cell surfaces and the surrounding extracellular environments. Because cells respond to stimuli by altering glycan expression, glycan structures vary according to spatial location in tissue and temporal factors. These dynamic structural expression patterns, combined with the essential roles glycans play in physiology, drive the need for analytical methods for glycoconjugates. In addition, recombinant glycoprotein drug products represent a multibillion dollar market. Effective analytical methods are needed to speed the identification of new targets and the development of industrial glycoprotein products, both new and biosimilar. Mass spectrometry is an enabling technology in glycomics. This review summarizes mass spectrometry of glycoconjugate glycans. The intent is to summarize appropriate methods for glycans given their chemical properties as distinct from those of proteins, lipids, and small molecule metabolites. Special attention is given to the uses of mass spectral profiling for glycomics with respect to the N-linked, O-linked, ganglioside, and glycosaminoglycan compound classes. Next, the uses of tandem mass spectrometry of glycans are summarized. The review finishes with an update on mass spectral glycoproteomics.

2010-01-01

357

Direct mass spectrometric monitoring of solid phase organic syntheses.  

PubMed

Direct on-bead monitoring of solid-phase reactions is possible with soft laser desorption time-of-flight mass spectrometry (SLD-TOF MS) without prior cleavage from the resin if photocleavable phenacyl ester or o-nitroveratryl linker groups are employed. PMID:14606810

Gerdes, Jantje M; Waldmann, Herbert

2003-01-01

358

SELDI-TOF MS Whole Serum Proteomic Profiling with IMAC Surface Does Not Reliably Detect Prostate Cancer  

Microsoft Academic Search

BACKGROUND: The analysis of bodily fluids using SELDI- TOF MS has been reported to identify signatures of spectral peaks that can be used to differentiate patients withaspecificdiseasefromnormalorcontrolpatients. This report is the 2nd of 2 companion articles describ- ing a validation study of a SELDI-TOF MS approach with IMAC surface sample processing to identify pros- tatic adenocarcinoma. METHODS: We sought to

Dale McLerran; William E. Grizzle; Ziding Feng; Ian M. Thompson; William L. Bigbee; Lisa H. Cazares; Daniel W. Chan; Jackie Dahlgren; Jose Diaz; Jacob Kagan; Daniel W. Lin; Gunjan Malik; Denise Oelschlager; Alan Partin; Timothy W. Randolph; Lori Sokoll; Shiv Srivastava; Sudhir Srivastava; Mark Thornquist; Dean Troyer; George L. Wright; Zhen Zhang; Liu Zhu; O. John Semmes

359

Dihydrobenzoic acid modified nanoparticle as a MALDI-TOF MS matrix for soft ionization and structure determination of small molecules with diverse structures.  

PubMed

Efficient structural characterization is important for quality control when developing novel materials. In this study, we demonstrated the soft ionization capability of the hybrid of immobilized silica and 2,5-dihydrobenzoic acid (DHB) on iron oxide magnetic nanoparticles in MALDI-TOF MS with a clean background. The ratio between SiO(2) and DHB was examined and was found to affect the surface immobilization of DHB on the nanoparticle, critically controlling the ionization efficiency and interference background. Compared with commercial DHB, the functionalized nanoparticle-assisted MALDI-TOF MS provided superior soft ionization with production of strong molecular ions within 5 ppm mass accuracy on a variety of new types of synthetic materials used for solar cells, light emitting devices, dendrimers, and glycolipids, including analytes with either thermally labile structures or poor protonation tendencies. In addition, the enhancements of the molecular ion signal also provided high-quality product-ion spectra allowing structural characterization and unambiguous small molecule identification. Using this technique, the structural differences among the isomers were distinguished through their characteristic fragment ions and comprehensive fragmentation patterns. With the advantages of long-term stability and simple sample preparation by deposition on a regular sample plate, the use of DHB-functionalized nanoparticles combined with high-resolution MALDI-TOF MS provides a generic platform for rapid and unambiguous structure determination of small molecules. PMID:20739189

Tseng, Mei-Chun; Obena, Rofeamor; Lu, Ying-Wei; Lin, Po-Chiao; Lin, Ping-Yu; Yen, Yung-Sheng; Lin, Jiann-Tsuen; Huang, Li-De; Lu, Kuang-Lieh; Lai, Long-Li; Lin, Chun-Cheng; Chen, Yu-Ju

2010-11-01

360

MASS SPECTROMETRY IN ENVIRONMENTAL SCIENCES  

EPA Science Inventory

This review covers applications of mass spectrometry to the environmental sciences. From the early applications of mass spectrometry to environmental research in the 1960s and 1970s, mass spectrometry has played an important role in aiding our understanding of environmental poll...

361

Mass Spectrometry and Protein Analysis  

Microsoft Academic Search

Mass spectrometry is a central analytical technique for protein research and for the study of biomolecules in general. Driven by the need to identify, characterize, and quantify proteins at ever increasing sensitivity and in ever more complex samples, a wide range of new mass spectrometry-based analytical platforms and experimental strategies have emerged. Here we review recent advances in mass spectrometry

Bruno Domon; Ruedi Aebersold

2006-01-01

362

On-line Measurement of Biogenic Volatile Organic Compounds (BVOCs) and Their Oxidation Products by PTR-TOF-MS in a Forest Environment in the Southeastern U.S  

NASA Astrophysics Data System (ADS)

Biogenic volatile organic compounds (BVOCs) including isoprene, monoterpenes, sesquiterpenes and some oxygenated species emitted from vegetation comprise the largest fraction (about 90%) of global non-methane VOC emissions. The Southeastern U.S. experiences very high emissions of biogenic VOCs during the summertime because of high temperatures and heavy local forestation. To further understand the role of biogenic VOCs in shaping local and regional photochemistry, a Proton Transfer Reaction time-of-flight Mass Spectrometry (PTR-TOF-MS) was deployed at a forest site in eastern Tennessee from June 10th to July 16th, 2013 to measure mixing ratios of BVOCs and their oxidation products, as part of the Southern Oxidant and Aerosol Study (SOAS). Isoprene was observed to be the dominant BVOC species at the site, typically reaching a maximum mixing ratio of about 6 ppbv in the early afternoon. Mixing ratios of other biogenic VOCs such as monoterpenes were relatively low (<1ppb). Most of the time, methyl vinyl ketone and methacrolein (MVK+MACR), the major products from OH-initiated isoprene oxidation, tracked well with their precursor. Their mixing ratios typically increased in late morning and maintained relatively high levels in the afternoon and evening before decreasing gradually overnight. The possibility of distinguishing MVK and MACR using NO+ as a reagent ion in the PTR-TOF-MS was also explored. Combined with recent results from laboratory chamber experiments, the ratios between isoprene and its oxidation products are used to understand the oxidation pathways of isoprene in this biogenically-dominated area. Oxygenated VOCs (OVOCs), including formaldehyde and acetone, were also observed at the site. Multi-variate regression analysis of VOC time series is applied to identify contributions from biogenic and anthropogenic emissions and other possible sources, and to understand relationships between primary and secondary compounds in the atmosphere.

Liu, Y.; McKinney, K. A.

2013-12-01

363

Gold nanoparticles as assisted matrices for the detection of biomolecules in a high-salt solution through laser desorption\\/ionization mass spectrometry  

Microsoft Academic Search

Citrate-capped gold nanoparticles (AuNPs) serve as matrices for the determination of biomolecules in a high-salt solution\\u000a through matrix-assisted laser desorption\\/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). In the case of using\\u000a 2,5-dihydroxybenzoic acid (2,5-DHB) as a matrix, the signal intensities of neutral steroids were severely suppressed in a\\u000a high-salt solution. A high concentration of NaCl caused the formation of the sodium adduct

Hsin-Pin Wu; Cheng-Ju Yu; Chin-Yu Lin; Yen-Hsiu Lin; Wei-Lung Tseng

2009-01-01

364

Optimized Method for Acinetobacter Species Carbapenemase Detection and Identification by Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry  

PubMed Central

The use of matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) for rapid detection and identification of the enzymes responsible for carbapenem resistance in Acinetobacter spp. appears as a promising option, but it will be necessary to have a standardized protocol that facilitates routine use. Based on the results reported herein and comparisons of several previously published reports, we identified the significant peaks for imipenem detection. Optimal bacterial inoculum and incubation time were established, and results obtained with and without dipicolinic acid (DPA) and Zn2+ allowed us to distinguish between metallo-beta-lactamases and oxacillinases.

Picazo, Juan J.; Culebras, Esther

2013-01-01

365

Development of a MALDI two-layer volume sample preparation technique for analysis of colored conidia spores of Fusarium by MALDI linear TOF mass spectrometry  

Microsoft Academic Search

Matrix-assisted laser desorption\\/ionization time-of-flight mass spectrometry (MALDI–TOF MS) has been proved to be a powerful\\u000a tool for the identification and characterization of microorganisms based on their surface peptide\\/protein pattern. Because\\u000a of the complexity of microorganisms, there are no standardized protocols to acquire reproducible peptide\\/protein profiles\\u000a for a broad range of microorganisms and for fungi in particular. Small variations during MALDI

Hongjuan Dong; Jasmin Kemptner; Martina Marchetti-Deschmann; Christian Peter Kubicek; Günter Allmaier

2009-01-01

366

Biological Cluster Mass Spectrometry  

PubMed Central

This article reviews the new physics and new applications of secondary ion mass spectrometry using cluster ion probes. These probes, particularly C60, exhibit enhanced molecular desorption with improved sensitivity owing to the unique nature of the energy-deposition process. In addition, these projectiles are capable of eroding molecular solids while retaining the molecular specificity of mass spectrometry. When the beams are microfocused to a spot on the sample, bioimaging experiments in two and three dimensions are feasible. We describe emerging theoretical models that allow the energy-deposition process to be understood on an atomic and molecular basis. Moreover, experiments on model systems are described that allow protocols for imaging on biological materials to be implemented. Finally, we present recent applications of imaging to biological tissue and single cells to illustrate the future directions of this methodology.

Winograd, Nicholas; Garrison, Barbara J.

2010-01-01

367

Protein identification by MALDI-TOF mass spectrometry.  

PubMed

MALDI-TOF mass spectrometers are now commonplace and their relative ease of use means that most non-specialist labs can readily access the technology for the rapid and sensitive analysis of biomolecules. One of the main uses of MALDI-TOF-MS is in the identification of proteins, by peptide mass fingerprinting (PMF). Here we describe a simple protocol that can be performed in a standard biochemistry laboratory, whereby proteins separated by 1D or 2D gel electrophoresis can be identified at femtomole levels. The procedure involves excision of the spot or band from the gel, washing and destaining, reduction and alkylation, in-gel trypsin digestion, MALDI-TOF-MS of the tryptic peptides and database searching of the PMF data. Up to 96 protein samples can easily be manually processed at one time by this method. PMID:21964792

Webster, Judith; Oxley, David

2012-01-01

368

Effect of NaCl and sucrose tastants on protein composition of oral fluid analysed by SELDI-TOF-MS.  

PubMed

During eating, human saliva is secreted into the oral cavity by salivary glands. The relative contribution of different glands to total salivary flow rate depends, among other factors, on the tastants in the food. Few reports indicated that also the salivary protein composition depends on the tastant make-up of the food. We studied the influence of sodium-chloride- and sucrose solutions on the presence of proteins in the M(r) range 2-20kDa in whole saliva. Upon oral stimulation with a sodium chloride solution, a sucrose solution or water, we collected whole saliva from 14 volunteers after t=1 min, t=11 min and t=20 min. Saliva protein profiles were analysed by SELDI-TOF-MS. SELDI-TOF-MS intensities of m/z values representing different protein masses were compared between subjects, tastants and time conditions. For subsets of the 33 detected masses, significant effects were observed for all factors, with most masses involved in the Subjects effect: m/z(Subjects)>m/z(Time×Stimulus)>m/z(Stimulus)>m/z(Time). Most effects on saliva protein composition were observed at t=1 min, whilst almost no effects were observed at t=11 min and t=20 min. When considering the Stimulus×Time interaction, we identified four different stimulus-response patterns. Proteins identified in the present study, and attributed to specific glands or tissues in literature, were used to associate stimulus-response patterns with tissue provenances. Observed stimulus-response patterns were not uniquely associated to particular glands and tissues. Hence, there was no evidence of the involvement of particular tissues or glands in tastant-specific protein responses. In conclusion, oral stimulation with different tastants affects salivary protein composition in a protein- and stimuli dependent way, which seems not be associated with any specific tissues or glands of origin. PMID:22541734

Silletti, E; Bult, J H F; Stieger, M

2012-09-01

369

Identification of amiodarone metabolites in human bile by ultraperformance liquid chromatography/quadrupole time-of-flight mass spectrometry.  

PubMed

Amiodarone is recognized as an effective drug in the treatment of arrhythmias. Previous experiments demonstrated that mono-N-desethylamiodarone (MDEA) was the major circulating metabolite in humans. In addition, dealkylation, hydroxylation, and deamination were minor metabolic pathways. The purpose of this study was to identify the metabolites of amiodarone in the bile obtained from patients with T-tube drainage after oral drug administration. Amiodarone metabolism in vitro was also investigated using human liver microsomes (HLMs) and S9 fraction. Ultraperformance liquid chromatography/quadrupole time-of-flight mass spectrometry (UPLC-Q/TOF MS) revealed 33 metabolites in human bile, including 22 phase I and 11 phase II metabolites. The major metabolites were MDEA (M7) and ?-carboxylate amiodarone (M12). Metabolite M12 was isolated from human bile, and the chemical structure was confirmed using UPLC-Q/TOF MS and ¹H NMR. Moreover, the authentic standards of two hydroxylated metabolites, 2-hydroxylamiodarone and 3'-hydroxylamiodarone, were obtained through microbial transformation. Several novel metabolic pathways of amiodarone in human were proposed, including ?-carboxylation, deiodination, and glucuronidation. The in vitro study demonstrated that incubation of HLMs with amiodarone did not give rise to any carboxyl metabolites. In contrast, M12 and its metabolites were detected in human liver S9 incubation samples, and the production of these metabolites were inhibited almost completely by 4-methylpyrazole, an inhibitor of alcohol dehydrogenase, suggesting the involvement of alcohol dehydrogenase in the ?-carboxylation of amiodarone. Overall, UPLC-Q/TOF MS analysis leads to the discovery of several novel amiodarone metabolites in human bile and underscores the importance of bile as an excretion pathway. PMID:21398391

Deng, Pan; You, Tiangeng; Chen, Xiaoyan; Yuan, Tao; Huang, Haihua; Zhong, Dafang

2011-06-01

370

Evaluation of matrix-assisted laser desorption ionization-time of flight mass spectrometry for identification of nocardia species.  

PubMed

The identification of Nocardia species, usually based on biochemical tests together with phenotypic in vitro susceptibility and resistance patterns, is a difficult and lengthy process owing to the slow growth and limited reactivity of these bacteria. In this study, a panel of 153 clinical and reference strains of Nocardia spp., altogether representing 19 different species, were characterized by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). As reference methods for species identification, full-length 16S rRNA gene sequencing and phenotypical biochemical and enzymatic tests were used. In a first step, a complementary homemade reference database was established by the analysis of 110 Nocardia isolates (pretreated with 30 min of boiling and extraction) in the MALDI BioTyper software according to the manufacturer's recommendations for microflex measurement (Bruker Daltonik GmbH, Leipzig, Germany), generating a dendrogram with species-specific cluster patterns. In a second step, the MALDI BioTyper database and the generated database were challenged with 43 blind-coded clinical isolates of Nocardia spp. Following addition of the homemade database in the BioTyper software, MALDI-TOF MS provided reliable identification to the species level for five species of which more than a single isolate was analyzed. Correct identification was achieved for 38 of the 43 isolates (88%), including 34 strains identified to the species level and 4 strains identified to the genus level according to the manufacturer's log score specifications. These data suggest that MALDI-TOF MS has potential for use as a rapid (<1 h) and reliable method for the identification of Nocardia species without any substantial costs for consumables. PMID:20861335

Verroken, A; Janssens, M; Berhin, C; Bogaerts, P; Huang, T-D; Wauters, G; Glupczynski, Y

2010-11-01

371

MALDI Mass Spectrometry Imaging of Neuronal Cell Cultures  

PubMed Central

Mass spectrometry imaging (MSI) provides the ability to detect and identify a broad range of analytes and their spatial distributions from a variety of sample types, including tissue sections. Here we describe an approach for probing neuropeptides from sparse cell cultures using matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) MSI—at single cell spatial resolution—in both MS and tandem MS modes. Cultures of Aplysia californica neurons are grown on an array of glass beads embedded in a stretchable layer of Parafilm M. As the membrane is stretched, the beads/neurons are separated physically and the separated beads/neurons analyzed via MALDI TOF MS. Compared with direct MS imaging of samples, the stretching procedure enhances analyte extraction and incorporation into the MALDI matrix, with negligible analyte spread between separated beads. MALDI tandem MSI using the stretched imaging approach yields localization maps of both parent and fragment ions from Aplysia pedal peptide, thereby confirming peptide identification. This methodology represents a flexible platform for MSI investigation of a variety of cell cultures, including functioning neuronal networks.

Zimmerman, Tyler A.; Rubakhin, Stanislav S.; Sweedler, Jonathan V.

2011-01-01

372

Comparison of ZnS semiconductor nanoparticles capped with various functional groups as the matrix and affinity probes for rapid analysis of cyclodextrins and proteins in surface-assisted laser desorption/ionization time-of-flight mass spectrometry.  

PubMed

Zinc sulfide (ZnS) semiconductor nanoparticles (NPs) capped with a variety of functional groups including bare ZnS NPs, 3-mercaptopropanoic acid (ZnS-3-MPA), sodium citrate (ZnS-citrate), cysteamine (ZnS-Cys), and 2-mercaptoethane sulfonate (ZnS-2-MES) have been investigated as the matrix and affinity probes for analysis of alpha-, beta-, and gamma-cyclodextrins (CDs), ubiquitin, and insulin in biological samples by using surface-assisted laser desorption/ionization time-of-flight mass spectrometry (SALDI-TOF-MS). Various parameters that would influence the ionization efficiency and sensitivity of these ZnS NPs in SALDI-TOF-MS were examined including the effect of capping agents, sample pH, ion abundance, and concentration of ZnS NPs. Among these ZnS NPs, our results have demonstrated that ZnS-3-MPA exhibited the highest efficiency toward CDs, ubiquitin, and insulin for high-sensitivity detection in SALDI-TOF-MS. The detection limits were 20-55 nM for CDs, 91 nM for ubiquitin, and 85 nM for insulin. The applicability of the present method is demonstrated by detection of ubiquitin-like proteins in oyster mushroom and also in the analysis of analytes in bio