Factors influencing the latency of simple reaction time

PubMed Central

Woods, David L.; Wyma, John M.; Yund, E. William; Herron, Timothy J.; Reed, Bruce

2015-01-01

Simple reaction time (SRT), the minimal time needed to respond to a stimulus, is a basic measure of processing speed. SRTs were first measured by Francis Galton in the 19th century, who reported visual SRT latencies below 190 ms in young subjects. However, recent large-scale studies have reported substantially increased SRT latencies that differ markedly in different laboratories, in part due to timing delays introduced by the computer hardware and software used for SRT measurement. We developed a calibrated and temporally precise SRT test to analyze the factors that influence SRT latencies in a paradigm where visual stimuli were presented to the left or right hemifield at varying stimulus onset asynchronies (SOAs). Experiment 1 examined a community sample of 1469 subjects ranging in age from 18 to 65. Mean SRT latencies were short (231, 213 ms when corrected for hardware delays) and increased significantly with age (0.55 ms/year), but were unaffected by sex or education. As in previous studies, SRTs were prolonged at shorter SOAs and were slightly faster for stimuli presented in the visual field contralateral to the responding hand. Stimulus detection time (SDT) was estimated by subtracting movement initiation time, measured in a speeded finger tapping test, from SRTs. SDT latencies averaged 131 ms and were unaffected by age. Experiment 2 tested 189 subjects ranging in age from 18 to 82 years in a different laboratory using a larger range of SOAs. Both SRTs and SDTs were slightly prolonged (by 7 ms). SRT latencies increased with age while SDT latencies remained stable. Precise computer-based measurements of SRT latencies show that processing speed is as fast in contemporary populations as in the Victorian era, and that age-related increases in SRT latencies are due primarily to slowed motor output. PMID:25859198

Rapid screening and quantification of residual pesticides and illegal adulterants in red wine by direct analysis in real time mass spectrometry.

PubMed

Guo, Tianyang; Fang, Pingping; Jiang, Juanjuan; Zhang, Feng; Yong, Wei; Liu, Jiahui; Dong, Yiyang

2016-11-04

A rapid method to screen and quantify multi-class analytic targets in red wine has been developed by direct analysis in real time (DART) coupled with triple quadruple tandem mass spectrometry (QqQ-MS). A modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) procedure was used for increasing analytical speed and reducing matrix effect, and the multiple reaction monitoring (MRM) in DART-MS/MS ensured accurate analysis. One bottle of wine containing 50 pesticides and 12 adulterants, i.e., preservatives, antioxidant, sweeteners, and azo dyes, could be totally determined less than 12min. This method exhibited proper linearity (R 2 ≥0.99) in the range of 1-1000ng/mL for pesticides and 10-5000ng/mL for adulterants. The limits of detection (LODs) were obtained in a 0.5-50ng/mL range for pesticides and 5-50ng/mL range for adulterants, and the limits of quantification (LOQs) were in a 1-100ng/mL range for pesticides and 10-250ng/mL range for adulterants. Three spiked levels for each analyte in wine were evaluated, and the recoveries were in a scope of 75-120%. The results demonstrated DART-MS/MS was a rapid and simple method, and could be applied to rapid analyze residual pesticides and illegal adulterants in a large quantities of red wine. Copyright © 2016 Elsevier B.V. All rights reserved.

Determination of phenylalanine isotope ratio enrichment by liquid chromatography/time- of-flight mass spectrometry.

PubMed

Wu, Zhanpin; Zhang, Xiao-Jun; Cody, Robert B; Wolfe, Robert R

2004-01-01

The application of time-of-flight mass spectrometry to isotope ratio measurements has been limited by the relatively low dynamic range of the time-to-digital converter detectors available on commercial LC/ToF-MS systems. Here we report the measurement of phenylalanine isotope ratio enrichment by using a new LC/ToF-MS system with wide dynamic range. Underivatized phenylalanine was injected onto a C18 column directly with 0.1% formic acid/acetonitrile as the mobile phase. The optimal instrument parameters for the time-of-flight mass spectrometer were determined by tuning the instrument with a phenylalanine standard. The accuracy of the isotope enrichment measurement was determined by the injection of standard solutions with known isotope ratios ranging from 0.02% to 9.2%. A plot of the results against the theoretical values gave a linear curve with R2 of 0.9999. The coefficient of variation for the isotope ratio measurement was below 2%. The method is simple, rapid, and accurate and presents an attractive alternative to traditional GC/MS applications.

Design and performance simulation of 532 nm Rayleigh-Mie Doppler lidar system for 5-50 km wind measurement

NASA Astrophysics Data System (ADS)

Shen, Fahua; Wang, Bangxin; Shi, Wenjuan; Zhuang, Peng; Zhu, Chengyun; Xie, Chenbo

2018-04-01

A novel design of the 532 nm Rayleigh-Mie Doppler lidar receiving system is carried out. The use of polarization isolation technology to effectively improve the receiving system optical reception efficiency, suppress the background noise, not only improves the system wind field detection accuracy, while achieving a high-accuracy temperature measurement. The wind speed and temperature measurement principle of the system are discussed in detail, and the triple Fabry-Perot etalon parameters are optimized. Utilizing the overall design parameters of the system, the system detection performance is simulated. The simulation results show that from 5 to 50 km altitude with vertical resolution of 0.1 km@5 ∼20 km, 0.5 km@20 ∼40 km, 1 km@40 ∼50 km, by using the laser with single pulse energy of 600 mJ, repetition frequency of 50 Hz and the receiving telescope with aperture of 0.8 m, with 2min integration time and in ±50 m/s radial wind speed range, the radial wind speed measurement accuracies of our designed lidar in the day and night are better than 2.6 m/s and 0.9 m/s respectively, and its performance is obviously superior to that of traditional system 5.6 m/s and 1.4 m/s wind speed accuracies; with 10min integration time and in 210 ∼280 K temperature range, the temperature measurement accuracies of the system in the day and night are better than 3.4 K and 1.2 K respectively; since the wind speed sensitivities of the Mie and Rayleigh scattering signals are not exactly the same, in ±50 m/s radial wind speed range, the wind speed bias induced by Mie signal is less than 1 m/s in the temperature range of 210-290 K and in the backscatter ratio range of 1-1.5 for pair measurement.

Determination of chlormequat in pig serum and sow milk by LC-MS/MS.

PubMed

Poulsen, M E; Christensen, H B; Sørensen, M T; Leffers, H; Andersen, J H

2007-11-01

Chlormequat is a plant growth regulator widely used on cereals, and there is general concern that it may impair human fertility. A LC-MS/MS method for the analysis of chlormequat in milk and serum was developed and validated in connection with an investigation on the effect of chlormequat on pig reproduction. Validation of the method was based on recovery tests at three spiking levels, determined as double determinations and repeated at least four times. Samples were extracted with methanol-water-acetic acid, centrifuged, filtrated and determined by LC-MS/MS. The mean recoveries were in the range 80-110%, and the LOD was 0.2 ng/g for serum and 0.3 ng/g for milk. The values for repeatability and reproducibility were within 2/3 of the limits given by the Horwitz equation. Samples of pig serum (59) and sow milk (27) were analyzed using the method. Chlormequat was determined in four milk samples in the range of 0.4 ng/g to 1.2 ng/g and in all serum samples in the range of 0.2 ng/g-4.0 ng/g.

Factors associated with gait speed recovery after total knee arthroplasty: A longitudinal study.

PubMed

Pua, Yong-Hao; Seah, Felicia Jie-Ting; Clark, Ross Allan; Lian-Li Poon, Cheryl; Tan, John Wei-Ming; Chong, Hwei-Chi

2017-04-01

Gait speed limitations can remain significant issues after a total knee arthroplasty (TKA) but their associated factors are not well understood. This study aimed to identify the factors associated with acute gait speed recovery post-TKA. We performed a prospective longitudinal study of 1765 patients who underwent primary TKA between July 2013 and July 2015. At 4, 8, 12, and 16 weeks postsurgery, fast gait speed was measured. The factors associated with gait speed over time since TKA were identified using multivariable generalized least squares modeling. Lower postoperative quadriceps strength and knee flexion range of motion were closely associated with lower gait speed over time (0.084m/s, 0.064m/s, and 0.055m/s change in gait speed per interquartile range change in ipsilateral quadriceps strength, contralateral quadriceps strength, and knee flexion range of motion, respectively). Additional strong predictors of lower gait speed included older age (0.11m/s), lower levels of preoperative Short Form 36 physical function (0.066m/s), greater body mass (0.046m/s), and the preoperative use of a walking aid (overall P < 0.001). Patients who reported that they limited their daily activities due to a fear of falling also had poorer gait speed (0.033m/s and 0.054m/s slower gait speed for "Occasional" and "Often" categories, respectively, vs. "None"). Gait speed recovery post-TKA is driven by both physical and psychological factors, suggesting that identifying and treating the underlying physical and cognitive causes of gait speed limitations may be crucial to optimize functional recovery. Copyright © 2017 Elsevier Inc. All rights reserved.

Sub-Microsecond Temperature Measurement in Liquid Water Using Laser Induced Thermal Acoustics

NASA Technical Reports Server (NTRS)

Alderfer, David W.; Herring, G. C.; Danehy, Paul M.; Mizukaki, Toshiharu; Takayama, Kazuyoshi

2005-01-01

Using laser-induced thermal acoustics, we demonstrate non-intrusive and remote sound speed and temperature measurements over the range 10 - 45 C in liquid water. Averaged accuracy of sound speed and temperature measurements (10 s) are 0.64 m/s and 0.45 C respectively. Single-shot precisions based on one standard deviation of 100 or greater samples range from 1 m/s to 16.5 m/s and 0.3 C to 9.5 C for sound speed and temperature measurements respectively. The time resolution of each single-shot measurement was 300 nsec.

Real-time processing for full-range Fourier-domain optical-coherence tomography with zero-filling interpolation using multiple graphic processing units.

PubMed

Watanabe, Yuuki; Maeno, Seiya; Aoshima, Kenji; Hasegawa, Haruyuki; Koseki, Hitoshi

2010-09-01

The real-time display of full-range, 2048?axial pixelx1024?lateral pixel, Fourier-domain optical-coherence tomography (FD-OCT) images is demonstrated. The required speed was achieved by using dual graphic processing units (GPUs) with many stream processors to realize highly parallel processing. We used a zero-filling technique, including a forward Fourier transform, a zero padding to increase the axial data-array size to 8192, an inverse-Fourier transform back to the spectral domain, a linear interpolation from wavelength to wavenumber, a lateral Hilbert transform to obtain the complex spectrum, a Fourier transform to obtain the axial profiles, and a log scaling. The data-transfer time of the frame grabber was 15.73?ms, and the processing time, which includes the data transfer between the GPU memory and the host computer, was 14.75?ms, for a total time shorter than the 36.70?ms frame-interval time using a line-scan CCD camera operated at 27.9?kHz. That is, our OCT system achieved a processed-image display rate of 27.23 frames/s.

Micro-solid-phase extraction (µ-SPE) of organophosphorous pesticides from wheat followed by LC-MS/MS determination.

PubMed

Della Pelle, Flavio; Di Crescenzo, Maria Chiara; Sergi, Manuel; Montesano, Camilla; Di Ottavio, Francesca; Scarpone, Rossana; Scortichini, Giampiero; Compagnone, Dario

2016-01-01

A rapid, selective and effective method of extraction, clean-up and concentration of organophosphorous pesticides from wheat followed by electrospray (ESI) LC-MS/MS analysis was developed. The μ-SPE (micro-solid-phase extraction) procedure resulted in good analytical performance and reduced at the same time matrix effects, analysis time and solvent consumption. Limits of detection (LODs) and quantification (LOQs) were in the range of 0.3-10 and 1-30 μg kg(-1), respectively, with good reproducibility (RSD ≤ 13.8) and recoveries between 75% and 109%. Coefficients of determination (r(2)) were greater than 0.996 for the studied pesticides. Despite the reduced sorbent bed mass of μ-SPE tips (4.2 mg), the analytical data showed that no saturation phenomena occurs in the tested range of concentration both for single compounds and mixtures. Several real samples were analysed and the concentrations of the selected pesticides were found to be below the respective maximum residue limit (MRLs).

Statistical Studies of the Electric Breakdown in Nitrogen in the Duration Range of 3 ms-60 min

NASA Astrophysics Data System (ADS)

Gorokhov, V. V.; Karelin, V. I.; Perminov, A. V.; Repin, P. B.

2018-05-01

The statistical characteristics of an electric breakdown in the nitrogen in the spike (cathode)-plane gap in the duration range of (3 × 10-3)-3600 s at voltages close to a static breakdown have been studied. It has been found that a probability of a gap breakdown is nonmonotonously distributed over time. The presence of maxima in the probability distribution confirms a contribution of some processes that both stimulate and suppress a breakdown. The typical times of the processes are 30 ms, 10-1 s, and 300 s.

High-frame-rate infrared and visible cameras for test range instrumentation

NASA Astrophysics Data System (ADS)

Ambrose, Joseph G.; King, B.; Tower, John R.; Hughes, Gary W.; Levine, Peter A.; Villani, Thomas S.; Esposito, Benjamin J.; Davis, Timothy J.; O'Mara, K.; Sjursen, W.; McCaffrey, Nathaniel J.; Pantuso, Francis P.

1995-09-01

Field deployable, high frame rate camera systems have been developed to support the test and evaluation activities at the White Sands Missile Range. The infrared cameras employ a 640 by 480 format PtSi focal plane array (FPA). The visible cameras employ a 1024 by 1024 format backside illuminated CCD. The monolithic, MOS architecture of the PtSi FPA supports commandable frame rate, frame size, and integration time. The infrared cameras provide 3 - 5 micron thermal imaging in selectable modes from 30 Hz frame rate, 640 by 480 frame size, 33 ms integration time to 300 Hz frame rate, 133 by 142 frame size, 1 ms integration time. The infrared cameras employ a 500 mm, f/1.7 lens. Video outputs are 12-bit digital video and RS170 analog video with histogram-based contrast enhancement. The 1024 by 1024 format CCD has a 32-port, split-frame transfer architecture. The visible cameras exploit this architecture to provide selectable modes from 30 Hz frame rate, 1024 by 1024 frame size, 32 ms integration time to 300 Hz frame rate, 1024 by 1024 frame size (with 2:1 vertical binning), 0.5 ms integration time. The visible cameras employ a 500 mm, f/4 lens, with integration time controlled by an electro-optical shutter. Video outputs are RS170 analog video (512 by 480 pixels), and 12-bit digital video.

Modeling Sluggishness in Binaural Unmasking of Speech for Maskers With Time-Varying Interaural Phase Differences

PubMed Central

Brand, Thomas

2018-01-01

In studies investigating binaural processing in human listeners, relatively long and task-dependent time constants of a binaural window ranging from 10 ms to 250 ms have been observed. Such time constants are often thought to reflect “binaural sluggishness.” In this study, the effect of binaural sluggishness on binaural unmasking of speech in stationary speech-shaped noise is investigated in 10 listeners with normal hearing. In order to design a masking signal with temporally varying binaural cues, the interaural phase difference of the noise was modulated sinusoidally with frequencies ranging from 0.25 Hz to 64 Hz. The lowest, that is the best, speech reception thresholds (SRTs) were observed for the lowest modulation frequency. SRTs increased with increasing modulation frequency up to 4 Hz. For higher modulation frequencies, SRTs remained constant in the range of 1 dB to 1.5 dB below the SRT determined in the diotic situation. The outcome of the experiment was simulated using a short-term binaural speech intelligibility model, which combines an equalization–cancellation (EC) model with the speech intelligibility index. This model segments the incoming signal into 23.2-ms time frames in order to predict release from masking in modulated noises. In order to predict the results from this study, the model required a further time constant applied to the EC mechanism representing binaural sluggishness. The best agreement with perceptual data was achieved using a temporal window of 200 ms in the EC mechanism. PMID:29338577

Modeling Sluggishness in Binaural Unmasking of Speech for Maskers With Time-Varying Interaural Phase Differences.

PubMed

Hauth, Christopher F; Brand, Thomas

2018-01-01

In studies investigating binaural processing in human listeners, relatively long and task-dependent time constants of a binaural window ranging from 10 ms to 250 ms have been observed. Such time constants are often thought to reflect "binaural sluggishness." In this study, the effect of binaural sluggishness on binaural unmasking of speech in stationary speech-shaped noise is investigated in 10 listeners with normal hearing. In order to design a masking signal with temporally varying binaural cues, the interaural phase difference of the noise was modulated sinusoidally with frequencies ranging from 0.25 Hz to 64 Hz. The lowest, that is the best, speech reception thresholds (SRTs) were observed for the lowest modulation frequency. SRTs increased with increasing modulation frequency up to 4 Hz. For higher modulation frequencies, SRTs remained constant in the range of 1 dB to 1.5 dB below the SRT determined in the diotic situation. The outcome of the experiment was simulated using a short-term binaural speech intelligibility model, which combines an equalization-cancellation (EC) model with the speech intelligibility index. This model segments the incoming signal into 23.2-ms time frames in order to predict release from masking in modulated noises. In order to predict the results from this study, the model required a further time constant applied to the EC mechanism representing binaural sluggishness. The best agreement with perceptual data was achieved using a temporal window of 200 ms in the EC mechanism.

Timed instrumental activities of daily living in multiple sclerosis: The test of everyday cognitive ability (TECA).

PubMed

Charvet, Leigh E; Shaw, Michael T; Sherman, Kathleen; Haas, Shannon; Krupp, Lauren B

2018-05-03

Cognitive impairment is a common symptom of multiple sclerosis (MS) that can lead to declines in daily functioning. Timed instrumental activities of daily living (TIADLs) have been useful to bridge between cognitive testing and real-world functioning in disorders such as Alzheimer's disease and other dementias. However, these have not been standardized for general use, and the tasks that are typically employed have not been sensitive to the detection of milder forms of cognitive deficits. We developed a test of ten TIADLs tasks to measure a broader range of functioning, entitled the "Test of Everyday Cognitive Ability" or TECA, and tested its utility in a diverse sample of participants with MS. TECA performance was characterized in n = 177 participants with MS and compared to healthy controls (n = 49). A subset from each group received repeated administration. In addition, all participants completed a standard battery of neuropsychological measures. TECA performances were significantly different between MS and control participants. Further, MS participants with cognitive impairment performed significantly slower relative to those MS participants without impairment. The TECA is a TIADLs assessment appropriate for use in those with MS as it includes a broad range of task difficulties, requires minimum motor involvement, and is sensitive to MS-related cognitive impairment. The TECA is a brief and repeatable test of TIADLs and its ease of administration makes it suitable for both clinical practice and research settings. Copyright © 2018 Elsevier B.V. All rights reserved.

13C-NMR spectra and contact time experiment for Skjervatjern fulvic and humic acids

USGS Publications Warehouse

Malcolm, R.L.

1992-01-01

The T(CP) and T(1p) time constants for Skjervatjern fulvic and humic acids were determined to be short with T(CP) values ranging from 0.14 ms to 0.53 ms and T(1p) values ranging from 3.3 ms to 5.9 ms. T(CP) or T(1p) time constants at a contact time of 1 ms are favorable for quantification of 13C-NMR spectra. Because of the short T(CP) values, correction factors for signal intensity for various regions of the 13C-NMR spectra would be necessary at contact times greater than 1.1 ms or less than 0.9 ms. T(CP) and T(1p) values have a limited non-homogeneity within Skjervatjern fulvic and humic acids. A pulse delay or repeat time of 700 ms is more than adequate for quantification of these 13C-NMR spectra. Paramagnetic effects in these humic substances are precluded due to low inorganic ash contents, low contents of Fe, Mn, and Co, and low organic free-radical contents. The observed T(CP) values suggest that all the carbon types in Skjervatjern fulvic and humic acids are fully cross-polarized before significant proton relaxation occurs. The 13C-NMR spectra for Skjervatjern fulvic acid is similar to most aquatic fulvic acids as it is predominantly aliphatic, low in aromaticity (fa1 = 24), low in phenolic content, high in carboxyl content, and has no resolution of a methoxyl peak. The 13C-NMR spectra for Skjervatjern humic acid is also similar to most other aquatic humic acids in that it is also predominantly aliphatic, high in aromaticity (fa1 = 38), moderate in phenolic content, moderate in carboxyl content, and has a clear resolution of a methoxyl carbon region. After the consideration of the necessary 13C-NMR experimental conditions, these spectra are considered to be quantitative. With careful consideration of the previously determined 13C-NMR experimental conditions, quantitative spectra can be obtained for humic substances in the future from the HUMEX site. Possible changes in humic substances due to acidification should be determined from 13C-NMR data.

A window on perception: Response times of odontocete cetaceans in audiometric tests

NASA Astrophysics Data System (ADS)

Blackwood, Diane J.; Ridgway, Sam H.; Evans, William E.

2002-05-01

A standard psychometric measurement is response time, the interval elapsing between a stimulus and a response. While studies of response time have been published for humans and other terrestrial mammals, this study marks the first report of response times for odontocete cetaceans at threshold in an audiometric task. Two white whales (Delphinapterus leucas) and four Atlantic bottlenose dolphins (Tursiops truncatus) were given audiometric tests to determine masked hearing thresholds. Animals were tested at 26 frequencies over a range from 200 Hz to 100 kHz using pure tones. The test tone amplitudes covered a range of 20 dB re 1 microPascal including the hearing threshold of the animal at that frequency. Hearing thresholds varied from 87.5 dB to 125.5 dB depending on frequency, masking noise intensity and individual animal. Data was analyzed to determine characteristic relationships between response time and amplitude of test tone for each frequency and animal. The two whales responded significantly slower (640 ms, 0.001) than the four dolphins (430 ms). As in terrestrial animals, reaction time became shorter as stimulus strength increased. At threshold, median response time across frequencies within each animal varied about 150 ms.

Causes of death in critically ill multiple sclerosis patients.

PubMed

Karamyan, A; Brandtner, H; Grinzinger, S; Chroust, V; Bacher, C; Otto, F; Reisp, M; Hauer, L; Sellner, J

2017-10-01

Patients with multiple sclerosis (MS) experience higher mortality rates as compared to the general population. While the risk of intensive care unit (ICU) admission is also reported to be higher, little is known about causes of death CoD in critically ill MS patients. To study the causes of death (CoD) in the series of critically ill patients with MS verified by autopsy. We reviewed hospital electronic charts of MS patients treated at the neurological ICU of a tertiary care hospital between 2000 and 2015. We compared clinical and pathological CoD for those who were autopsied. Overall, 10 patients were identified (seven female; median age at death 65 years, range 27-80), and six of them were autopsied. The median MS duration prior to ICU admission was 27.5 years (range 1-50), and the median EDSS score at the time of ICU admission was 9 (range 5-9.5). The median length of ICU stay was 3 days (range 2-213). All the individuals in our series had experienced respiratory insufficiency during their ICU stay. The autopsy examination of brain tissue did not reveal evidences of MS lesions in one patient. In another patient, Lewy bodies were found on brain immunohistochemistry. Mortality in critically ill MS patients is largely driven by respiratory complications. Sporadic disparities between clinical and pathological findings can be expected. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

The utility of ultra-performance liquid chromatography/electrospray ionisation time-of-flight mass spectrometry for multi-residue determination of pesticides in strawberry.

PubMed

Taylor, Michael J; Keenan, George A; Reid, Kirsty B; Fernández, Diana Uría

2008-09-01

The utility of ultra-performance liquid chromatography/orthogonal-acceleration time-of flight mass spectrometry (UPLC/TOFMS) for the rapid qualitative and quantitative analysis of 100 pesticides targeted in strawberry was assessed by comparing results with those obtained using a validated in-house UPLC tandem mass spectrometry (MS/MS) multi-residue method. Crude extracts from retail strawberry samples received as part of the 2007 annual UK pesticide residues in food surveillance programme were screened for the presence of pesticide residues using UPLC/TOFMS. Accurate mass measurement of positive and negative ions allowed their extraction following 'full mass range data acquisition' with negligible interference from background or co-eluting species observed during UPLC gradient separation (in a cycle time of just 6.5 min per run). Extracted ion data was used to construct calibration curves and to detect and identify any incurred residues (i.e. pesticides incorporated in or on the test material following application during cultivation, harvest and storage). Calibration using matrix-matched standards was performed over a narrow concentration range of 0.005-0.04 mg kg(-1) with determination coefficients (r2) > or =0.99 for all analytes with the exception of malathion/fenarimol/fludioxanil (r2 = 0.98), quassia/pymetrazine (r2 = 0.97) and fenthion sulfone (r2 = 0.95). Residues found in selected samples ranged from 0.025-0.28 mg kg(-1) and were in excellent agreement with results obtained using UPLC/MS/MS. Mass measurement accuracies of < or =5 ppm were achieved consistently throughout the separation, mass range and concentration range of interest thus providing the opportunity to obtain discrete elemental compositions of target ions.

Fast and High Dynamic Range Imaging with Superconducting Tunnel Junction Detectors

NASA Astrophysics Data System (ADS)

Matsuo, Hiroshi

2014-08-01

We have demonstrated a combined test of the submillimeter-wave SIS photon detectors and GaAs-JFET cryogenic integrated circuits. A relatively large background photo-current can be read out by fast-reset integrating amplifiers. An integration time of 1 ms enables fast frame rate readout and large dynamic range imaging, with an expected dynamic range of 8,000 in 1 ms. Ultimate fast and high dynamic range performance of superconducting tunnel junction detectors (STJ) will be obtained when photon counting capabilities are employed. In the terahertz frequencies, when input photon rate of 100 MHz is measured, the photon bunching gives us enough timing resolution to be used as phase information of intensity fluctuation. Application of photon statistics will be a new tool in the terahertz frequency region. The design parameters of STJ terahertz photon counting detectors are discussed.

Large-scale pesticide testing in olives by liquid chromatography-electrospray tandem mass spectrometry using two sample preparation methods based on matrix solid-phase dispersion and QuEChERS.

PubMed

Gilbert-López, Bienvenida; García-Reyes, Juan F; Lozano, Ana; Fernández-Alba, Amadeo R; Molina-Díaz, Antonio

2010-09-24

In this work we have evaluated the performance of two sample preparation methodologies for the large-scale multiresidue analysis of pesticides in olives using liquid chromatography-electrospray tandem mass spectrometry (LC-MS/MS). The tested sample treatment methodologies were: (1) liquid-liquid partitioning with acetonitrile followed by dispersive solid-phase extraction clean-up using GCB, PSA and C18 sorbents (QuEChERS method - modified for fatty vegetables) and (2) matrix solid-phase dispersion (MSPD) using aminopropyl as sorbent material and a final clean-up performed in the elution step using Florisil. An LC-MS/MS method covering 104 multiclass pesticides was developed to examine the performance of these two protocols. The separation of the compounds from the olive extracts was achieved using a short C18 column (50 mm x 4.6 mm i.d.) with 1.8 microm particle size. The identification and confirmation of the compounds was based on retention time matching along with the presence (and ratio) of two typical MRM transitions. Limits of detection obtained were lower than 10 microgkg(-1) for 89% analytes using both sample treatment protocols. Recoveries studies performed on olives samples spiked at two concentration levels (10 and 100 microgkg(-1)) yielded average recoveries in the range 70-120% for most analytes when QuEChERS procedure is employed. When MSPD was the choice for sample extraction, recoveries obtained were in the range 50-70% for most of target compounds. The proposed methods were successfully applied to the analysis of real olives samples, revealing the presence of some of the target species in the microgkg(-1) range. Besides the evaluation of the sample preparation approaches, we also discuss the use of advanced software features associated to MRM method development that overcome several limitations and drawbacks associated to MS/MS methods (time segments boundaries, tedious method development/manual scheduling and acquisition limitations). This software feature recently offered by different vendors is based on an algorithm that associates retention time data for each individual MS/MS transition, so that the number of simultaneously traced transitions throughout the entire chromatographic run (dwell times and sensitivity) is maximized. Copyright 2010 Elsevier B.V. All rights reserved.

Occipital MEG Activity in the Early Time Range (<300 ms) Predicts Graded Changes in Perceptual Consciousness.

PubMed

Andersen, Lau M; Pedersen, Michael N; Sandberg, Kristian; Overgaard, Morten

2016-06-01

Two electrophysiological components have been extensively investigated as candidate neural correlates of perceptual consciousness: An early, occipitally realized component occurring 130-320 ms after stimulus onset and a late, frontally realized component occurring 320-510 ms after stimulus onset. Recent studies have suggested that the late component may not be uniquely related to perceptual consciousness, but also to sensory expectations, task associations, and selective attention. We conducted a magnetoencephalographic study; using multivariate analysis, we compared classification accuracies when decoding perceptual consciousness from the 2 components using sources from occipital and frontal lobes. We found that occipital sources during the early time range were significantly more accurate in decoding perceptual consciousness than frontal sources during both the early and late time ranges. These results are the first of its kind where the predictive values of the 2 components are quantitatively compared, and they provide further evidence for the primary importance of occipital sources in realizing perceptual consciousness. The results have important consequences for current theories of perceptual consciousness, especially theories emphasizing the role of frontal sources. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Ultrapyrolytic upgrading of plastic wastes and plastics/heavy oil mixtures to valuable light gas products

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lovett, S.; Berruti, F.; Behie, L.A.

1997-11-01

Viable operating conditions were identified experimentally for maximizing the production of high-value products such as ethylene, propylene, styrene, and benzene, from the ultrapyrolysis of waste plastics. Using both a batch microreactor and a pilot-plant-sized reactor, the key operating variables considered were pyrolysis temperature, product reaction time, and quench time. In the microreactor experiments, polystyrene (PS), a significant component of waste plastics, was pyrolyzed at temperatures ranging from 800 to 965 C, with total reaction times ranging from 500 to 1,000 ms. At a temperature of 965 C and 500 ms, the yields of styrene plus benzene were greater than 95more » wt %. In the pilot-plant experiments, the recently patented internally circulating fluidized bed (ICFB) reactor (Milne et al., US Patent Number 5,370,789, 1994b) was used to ultrapyrolyze low-density polyethylene (LDPE) in addition to LDPE (5% by weight)/heavy oil mixtures at a residence time of 600 ms. Both experiments produced light olefin yields greater than 55 wt % at temperatures above 830 C.« less

Rapid and reliable quantitation of amino acids and myo-inositol in mouse brain by high performance liquid chromatography and tandem mass spectrometry.

PubMed

Bathena, Sai P; Huang, Jiangeng; Epstein, Adrian A; Gendelman, Howard E; Boska, Michael D; Alnouti, Yazen

2012-04-15

Amino acids and myo-inositol have long been proposed as putative biomarkers for neurodegenerative diseases. Accurate measures and stability have precluded their selective use. To this end, a sensitive liquid chromatography tandem mass spectrometry (LC-MS/MS) method based on multiple reaction monitoring was developed to simultaneously quantify glutamine, glutamate, γ-aminobutyric acid (GABA), aspartic acid, N-acetyl aspartic acid, taurine, choline, creatine, phosphocholine and myo-inositol in mouse brain by methanol extractions. Chromatography was performed using a hydrophilic interaction chromatography silica column within in a total run time of 15 min. The validated method is selective, sensitive, accurate, and precise. The method has a limit of quantification ranging from 2.5 to 20 ng/ml for a range of analytes and a dynamic range from 2.5-20 to 500-4000 ng/ml. This LC-MS/MS method was validated for biomarker discovery in models of human neurological disorders. Copyright © 2012 Elsevier B.V. All rights reserved.

Comparison of capillary electrophoresis-mass spectrometry and hydrophilic interaction chromatography-mass spectrometry for anionic metabolic profiling of urine.

PubMed

Kok, Miranda G M; Somsen, Govert W; de Jong, Gerhardus J

2015-01-01

In order to assess the utility of a recently developed capillary electrophoresis-mass spectrometry (CE-MS) method for the study of anionic metabolites in urine, a comparison was made with hydrophilic interaction chromatography-MS (HILIC-MS) using negative electrospray ionization. After optimization of the HILIC conditions, a gradient employing 10mM ammonium acetate (pH 6.8) in acetonitrile-water (5 min 90% acetonitrile followed by 90%-50% acetonitrile in 10 min) was selected, providing baseline separation of five representative anionic test metabolites. Relative standard deviations (RSDs) for HILIC retention times and peak areas were below 0.2% and 7.7%, respectively, and detection limits were in the range 0.04-2.21 μM. Metabolites in rat urine could also be analysed in a reproducible way with retention time and peak area RSDs below 0.6% and 13.6%, respectively. The CE-MS and HILIC-MS methods were compared in terms of reproducibility, sensitivity, selectivity and coverage of the anionic urinary metabolome. In general, peak area RSDs were similar whereas HILIC-MS yielded better retention-time repeatability and up to 80 times lower detection limits (expressed in injected concentration) for test metabolites as compared to CE-MS. Rat urine analysis by HILIC-MS provided detection of 1360 molecular features compared to 347 molecular features revealed with CE-MS. Of these, a number of 144 molecular features were found with both HILIC-MS and CE-MS, which showed on average 10 times higher peak areas in HILIC-MS. The HILIC retention and CE migration times of the common features were clearly not correlated. The HILIC and CE behavior of the test metabolites and 16 putatively identified common features were evaluated involving their physicochemical properties, indicating a markedly different separation selectivity, and thus significant degree of orthogonality of HILIC and CE. Copyright © 2014 Elsevier B.V. All rights reserved.

Segmental analysis of amphetamines in hair using a sensitive UHPLC-MS/MS method.

PubMed

Jakobsson, Gerd; Kronstrand, Robert

2014-06-01

A sensitive and robust ultra high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method was developed and validated for quantification of amphetamine, methamphetamine, 3,4-methylenedioxyamphetamine and 3,4-methylenedioxy methamphetamine in hair samples. Segmented hair (10 mg) was incubated in 2M sodium hydroxide (80°C, 10 min) before liquid-liquid extraction with isooctane followed by centrifugation and evaporation of the organic phase to dryness. The residue was reconstituted in methanol:formate buffer pH 3 (20:80). The total run time was 4 min and after optimization of UHPLC-MS/MS-parameters validation included selectivity, matrix effects, recovery, process efficiency, calibration model and range, lower limit of quantification, precision and bias. The calibration curve ranged from 0.02 to 12.5 ng/mg, and the recovery was between 62 and 83%. During validation the bias was less than ±7% and the imprecision was less than 5% for all analytes. In routine analysis, fortified control samples demonstrated an imprecision <13% and control samples made from authentic hair demonstrated an imprecision <26%. The method was applied to samples from a controlled study of amphetamine intake as well as forensic hair samples previously analyzed with an ultra high performance liquid chromatography time of flight mass spectrometry (UHPLC-TOF-MS) screening method. The proposed method was suitable for quantification of these drugs in forensic cases including violent crimes, autopsy cases, drug testing and re-granting of driving licences. This study also demonstrated that if hair samples are divided into several short segments, the time point for intake of a small dose of amphetamine can be estimated, which might be useful when drug facilitated crimes are investigated. Copyright © 2014 John Wiley & Sons, Ltd.

Microwave and hard X-ray observations of a solar flare with a time resolution of better than 100 MS

NASA Technical Reports Server (NTRS)

Kaufmann, P.; Strauss, F. M.; Costa, J. E. R.; Dennis, B. R.; Kiplinger, A.; Frost, K. J.; Orwig, L. E.

1982-01-01

Simultaneous microwave and X-ray observations are presented for a solar flare detected on 1980 May 8 starting at 1937 UT. The X-ray observations were made with the Hard X-Ray Burst Spectrometer on the Solar Maximum Mission and covered the energy range from 28-490 keV with a time resolution of 10 ms. The microwave observations were made with the 5 and 45 foot antennas at the Itapetinga Radio Observatory at frequencies of 7 and 22 GHz, with time resolutions of 100 ms and 1 ms respectively. Detailed correlation analysis of the different time profiles of the event show that the major impulsive in the X-ray flux preceded the corresponding microwave peaks at 22 GHz by about 240ms. For this particular burst the 22 GHz peaks preceded the 7 GHz by about 1.5s. Observed delays of the microwave peaks are too large for a simple electron beam model but they can be reconciled with the speeds of shock waves in a thermal model.

Microwave and hard X-ray observations of a solar flare with a time resolution better than 100 ms

NASA Technical Reports Server (NTRS)

Kaufmann, P.; Costa, J. E. R.; Dennis, B. R.; Frost, K. J.; Orwig, L. E.; Kiplinger, A.; Strauss, F. M.

1983-01-01

Simultaneous microwave and X-ray observations are presented for a solar flare detected on 1980 May 8 starting at 1937 UT. The X-ray observations were made with the Hard X-ray Burst Spectrometer on the Solar Maximum Mission and covered the energy range from 28-490 keV with a time resolution of 10 ms. The microwave observations were made with the 5 and 45 foot antennas at the Itapetinga Radio Obervatory at frequencies of 7 and 22 GHz, with time resolutions of 100 ms and 1 ms respectively. Detailed correlation analysis of the different time profiles of the event show that the major impulsive in the X-ray flux preceded the corresponding microwave peaks at 22 GHz by about 240 ms. For this particular burst the 22 GHz peaks preceded the 7 GHz by about 1.5s. Observed delays of the microwave peaks are too large for a simple electron beam model but they can be reconciled with the speeds of shock waves in a thermal model. Previously announced in STAR as N82-30215

Quantitative measurement of salivary testosterone in Korean adults by stable isotope-dilution liquid chromatographyelectrospray-tandem mass spectrometry.

PubMed

Lee, Sanghoo; Kwon, Soonho; Shin, Hye-Jin; Park, Jimyeong; Lim, Hwan-Sub; Lee, Kyoung-Ryul; Kim, Young-Jin

2010-11-01

Salivary testosterone levels in Korean adults were quantitatively measured for the first time by liquid chromatography-electrospray-tandem mass spectrometry (LC ESI MS/MS). Salivary testosterone was separated on a multiple reaction monitoring (MRM) chromatogram within 7 min. The LC ESI MS/MS assay was validated over the linearity range of 0.01-2.00 ng/ml (r=0.99987) using testosterone-d(3) as an internal standard. The lower limit of quantification (LOQ) was 0.01 ng/ml. The intra- and inter-assay precisions were 1.54% to 4.09% and 0.96% to 4.29%, respectively. The mean recovery was 93.32% (range 88.43-98.05%). The validated assay was then applied to measure the salivary testosterone levels of Korean adults. In men, the salivary testosterone level collected between 9:00-11:00 am was approximately 2.8 times higher than that in women (P < 0.0001). Salivary testosterone levels in both sexes negatively correlated with age. The present assay would also be useful in measuring salivary testosterone levels in clinical laboratories.

Reaction time norms as measured by ruler drop method in school-going South Asian children: A cross-sectional study.

PubMed

Aranha, V P; Saxena, S; Moitra, M; Narkeesh, K; Arumugam, N; Samuel, A J

2017-01-01

This study aimed to estimate normative range for reaction time using ruler drop method for school-going South Asian children between 6 and 12 years of age. A cross-sectional study was used to evaluate the reaction time for 204 children. Normal values for each age group were obtained. The results of multiple linear regressions showed a decrease in the reaction time values with age, and a significant change occurring between six and eight years of age. No difference in reaction time was obtained between boys and girls. Ruler drop method is an easy to use test and the results of this study provide a normative data for age groups 6-12 years ranging from 214.2ms to 248.8ms. These values can serve as a reference to screen children with delayed reaction time. Copyright © 2016 Elsevier GmbH. All rights reserved.

Localization suppression and fusion measure of the precedence effect in young children

NASA Astrophysics Data System (ADS)

Litovsky, Ruth; Godar, Shelly; Yu, Gongqiang

2004-05-01

This study investigated aspects of the precedence effect (PE) known as fusion and localization dominance in children 4-5 years of age. Stimuli were three, 25-ms noise bursts (2-ms rise/fall times) with 250-ms ISI. On PE conditions the lead stimulus was presented from one of six locations in azimuth, and the lag was at 0 deg. Lead-lag delays varied from 5 to 100 ms. Localization was measured using an identification paradigm. Fusion was measured separately whereby subjects reported whether a single auditory event or two auditory events were perceived. Children reported two sounds on 75% of trials (fusion threshold) at delays ranging from 15 to 35 ms. Below fusion thresholds, the localization of the lead was similar to that of single-source stimuli. Above fusion thresholds lead localization was significantly degraded, persisting out to 100 ms. Localization of the lag was poor at all delays on which it was reported as being heard. According to these results localization dominance (difficulty localizing the lag) in children persists at greater delays than fusion, which is consistent with findings obtained in adult subjects. The range of delays over which these effects are robust in children is longer than the range observed in adults.

Broad-Range PCR Coupled with Electrospray Ionization Time of Flight Mass Spectrometry for Detection of Bacteremia and Fungemia in Patients with Neutropenic Fever

PubMed Central

Maertens, J.; Bueselinck, K.; Lagrou, K.

2016-01-01

Infection is an important complication in patients with hematologic malignancies or solid tumors undergoing intensive cytotoxic chemotherapy. In only 20 to 30% of the febrile neutropenic episodes, an infectious agent is detected by conventional cultures. In this prospective study, the performance of broad-range PCR coupled with electrospray ionization time of flight mass spectrometry (PCR/ESI-MS) technology was compared to conventional blood cultures (BC) in a consecutive series of samples from high-risk hematology patients. In 74 patients, BC and a whole-blood sample for PCR/ESI-MS (Iridica BAC BSI; Abbott, Carlsbad, CA, USA) were collected at the start of each febrile neutropenic episode and, in case of persistent fever, also at day 5. During 100 different febrile episodes, 105 blood samples were collected and analyzed by PCR/ESI-MS. There was evidence of a bloodstream infection (BSI) in 36/105 cases (34%), based on 14 cases with both PCR/ESI-MS and BC positivity, 17 cases with BC positivity only, and 5 cases with PCR/ESI-MS positivity only. The sensitivity of PCR/ESI-MS was 45%, specificity was 93%, and the negative predictive value was 80% compared to blood culture. PCR/ESI-MS detected definite pathogens (Fusobacterium nucleatum and Streptococcus pneumoniae) missed by BC, whereas it missed both Gram-negative and Gram-positive organisms detected by BC. PCR/ESI-MS testing detected additional microorganisms but showed a low sensitivity (45%) compared to BC in neutropenic patients. Our results indicate a lower concordance between BC and PCR/ESI-MS in the neutropenic population than what has been previously reported in other patient groups with normal white blood cell distribution, and a lower sensitivity than other PCR-based methods. PMID:27440820

Time-resolved multi-mass ion imaging: Femtosecond UV-VUV pump-probe spectroscopy with the PImMS camera.

PubMed

Forbes, Ruaridh; Makhija, Varun; Veyrinas, Kévin; Stolow, Albert; Lee, Jason W L; Burt, Michael; Brouard, Mark; Vallance, Claire; Wilkinson, Iain; Lausten, Rune; Hockett, Paul

2017-07-07

The Pixel-Imaging Mass Spectrometry (PImMS) camera allows for 3D charged particle imaging measurements, in which the particle time-of-flight is recorded along with (x, y) position. Coupling the PImMS camera to an ultrafast pump-probe velocity-map imaging spectroscopy apparatus therefore provides a route to time-resolved multi-mass ion imaging, with both high count rates and large dynamic range, thus allowing for rapid measurements of complex photofragmentation dynamics. Furthermore, the use of vacuum ultraviolet wavelengths for the probe pulse allows for an enhanced observation window for the study of excited state molecular dynamics in small polyatomic molecules having relatively high ionization potentials. Herein, preliminary time-resolved multi-mass imaging results from C 2 F 3 I photolysis are presented. The experiments utilized femtosecond VUV and UV (160.8 nm and 267 nm) pump and probe laser pulses in order to demonstrate and explore this new time-resolved experimental ion imaging configuration. The data indicate the depth and power of this measurement modality, with a range of photofragments readily observed, and many indications of complex underlying wavepacket dynamics on the excited state(s) prepared.

Liquid chromatography-tandem mass spectrometry characterization of five new leucinostatins produced by Paecilomyces lilacinus CG-189.

PubMed

Martinez, Ana Flávia Canovas; Moraes, Luiz Alberto Beraldo

2015-03-01

The fungus Paecilomyces lilacinus produces leucinostatins—peptaibiotics that exert a range of biological activities including antimalarial, antiviral, antitumor and phytotoxicity. In this paper, we developed an analytical method employing LC-MS/MS in the precursor ion and product ion scan modes to elucidate five new leucinostatins. Direct Infusion (DI-MS) helped to identify the most abundant leucinostatins: F, D B2, S, A and K. MS/MS analysis using a triple quadrupole operating at different scan modes is a versatile tool to study natural products, especially peptaibiotics. Although DI-MS full-scan analysis is rapid and sensitive, it cannot distinguish between peptide isomers. On the other hand, LC-MS/MS operated in the precursor ion and product ion modes is time consuming, but allows identifying the structure of isomers or isobar in crude extracts.

Patterned retinal coagulation with a scanning laser

NASA Astrophysics Data System (ADS)

Palanker, Daniel; Jain, ATul; Paulus, Yannis; Andersen, Dan; Blumenkranz, Mark S.

2007-02-01

Pan-retinal photocoagulation in patients with diabetic retinopathy typically involves application of more than 1000 laser spots; often resulting in physician fatigue and patient discomfort. We present a semi-automated patterned scanning laser photocoagulator that rapidly applies predetermined patterns of lesions; thus, greatly improving the comfort, efficiency and precision of the treatment. Patterns selected from a graphical user interface are displayed on the retina with an aiming beam, and treatment can be initiated and interrupted by depressing a foot pedal. To deliver a significant number of burns during the eye's fixation time, each pulse should be considerably shorter than conventional 100ms pulse duration. We measured coagulation thresholds and studied clinical and histological outcomes of the application of laser pulses in the range of 1-200ms in pigmented rabbits. Laser power required for producing ophthalmoscopically visible lesions with a laser spot of 132μm decreased from 360 to 37mW with pulse durations increasing from 1 to 100ms. In the range of 10-100ms clinically and histologically equivalent light burns could be produced. The safe therapeutic range of coagulation (ratio of the laser power required to produce a rupture to that for a light burn) decreased with decreasing pulse duration: from 3.8 at 100ms, to 3.0 at 20ms, to 2.5 at 10ms, and to 1.1 at 1ms. Histology demonstrated increased confinement of the thermal damage with shorter pulses, with coagulation zone limited to the photoreceptor layer at pulses shorter than 10ms. Durations of 10-20ms appear to be a good compromise between the speed and safety of retinal coagulation. Rapid application of multiple lesions greatly improves the speed, precision, and reduces pain in retinal photocoagulation.

Evaluation of Small Mass Spectrometer Systems

NASA Technical Reports Server (NTRS)

Arkin, C. Richard; Griffin, Timothy P.; Ottens, Andrew K.; Diaz, Jorge A.; Follistein, Duke W.; Adams, Fredrick W.; Helms, William R.; Voska, N. (Technical Monitor)

2002-01-01

This work is aimed at understanding the aspects of designing a miniature mass spectrometer (MS) system. A multitude of commercial and government sectors, such as the military, environmental agencies and industrial manufacturers of semiconductors, refrigerants, and petroleum products, would find a small, portable, rugged and reliable MS system beneficial. Several types of small MS systems are evaluated and discussed, including linear quadrupole, quadrupole ion trap, time of flight and sector. The performance of each system in terms of accuracy, precision, limits of detection, response time, recovery time, scan rate, volume and weight is assessed. A performance scale is setup to rank each systems and an overall performance score is given to each system. All experiments involved the analysis of hydrogen, helium, oxygen and argon in a nitrogen background with the concentrations of the components of interest ranging from 0-5000 part-per-million (ppm). The relative accuracies of the systems vary from < 1% to approx. 40% with an average below 10%. Relative precisions varied from 1% to 20%, with an average below 5%. The detection limits had a large distribution, ranging from 0.2 to 170 ppm. The systems had a diverse response time ranging from 4 s to 210 s as did the recovery time with a 6 s to 210 s distribution. Most instruments had scan times near, 1 s, however one instrument exceeded 13 s. System weights varied from 9 to 52 kg and sizes from 15 x 10(exp 3)cu cm to 110 x 10(exp 3) cu cm.

Manufacture of Autologous CD34+ Selected Grafts in the NIAID-Sponsored HALT-MS and SCOT Multicenter Clinical Trials for Autoimmune Diseases.

PubMed

Keever-Taylor, Carolyn A; Heimfeld, Shelly; Steinmiller, Kaitlyn C; Nash, Richard A; Sullivan, Keith M; Czarniecki, Christine W; Granderson, Tomeka C; Goldstein, Julia S; Griffith, Linda M

2017-09-01

To ensure comparable grafts for autologous hematopoietic cell transplantation (HCT) in the National Institute of Allergy and Infectious Diseases-sponsored Investigational New Drug protocols for multiple sclerosis (HALT-MS) and systemic sclerosis (SCOT), a Drug Master File approach to control manufacture was implemented, including a common Master Production Batch Record and site-specific standard operating procedures with "Critical Elements." We assessed comparability of flow cytometry and controlled rate cryopreservation among sites and stability of cryopreserved grafts using hematopoietic progenitor cells (HPCs) from healthy donors. Hematopoietic Progenitor Cells, Apheresis-CD34+ Enriched, for Autologous Use (Auto-CD34 + HPC) graft specifications included ≥70% viable CD34 + cells before cryopreservation. For the 2 protocols, 110 apheresis collections were performed; 121 lots of Auto-CD34 + HPC were cryopreserved, and 107 of these (88.4%) met release criteria. Grafts were infused at a median of 25 days (range, 17 to 68) post-apheresis for HALT-MS (n = 24), and 25 days (range, 14 to 78) for SCOT (n = 33). Subjects received precryopreservation doses of a median 5.1 × 10 6 viable CD34 + cells/kg (range, 3.9 to 12.8)  for HALT-MS and 5.6 × 10 6 viable CD34 + cells/kg (range, 2.6 to 10.2) for SCOT. Recovery of granulocytes occurred at a median of 11 days (range, 9 to 15) post-HCT for HALT-MS and 10 days (range, 8 to 12) for SCOT, independent of CD34 + cell dose. Subjects received their last platelet transfusion at a median of 9 days (range, 6 to 16) for HALT-MS and 8 days (range, 6 to 23) for SCOT; higher CD34 + /kg doses were associated with faster platelet recovery. Stability testing of cryopreserved healthy donor CD34 + HPCs over 6 months of vapor phase liquid nitrogen storage demonstrated consistent 69% to 73% recovery of viable CD34 + cells. Manufacturing of Auto-CD34 + HPC for the HALT-MS and SCOT protocols was comparable across all sites and supportive for timely recovery of granulocytes and platelets. Published by Elsevier Inc.

Analysis of pesticide residues in strawberries and soils by GC-MS/MS, LC-MS/MS and two-dimensional GC-time-of-flight MS comparing organic and integrated pest management farming.

PubMed

Fernandes, Virgínia C; Lehotay, Steven J; Geis-Asteggiante, Lucía; Kwon, Hyeyoung; Mol, Hans G J; van der Kamp, Henk; Mateus, Nuno; Domingues, Valentina F; Delerue-Matos, Cristina

2014-01-01

This study analysed 22 strawberry and soil samples after their collection over the course of 2 years to compare the residue profiles from organic farming with integrated pest management practices in Portugal. For sample preparation, we used the citrate-buffered version of the quick, easy, cheap, effective, rugged, and safe (QuEChERS) method. We applied three different methods for analysis: (1) 27 pesticides were targeted using LC-MS/MS; (2) 143 were targeted using low pressure GC-tandem mass spectrometry (LP-GC-MS/MS); and (3) more than 600 pesticides were screened in a targeted and untargeted approach using comprehensive, two-dimensional gas chromatography time-of-flight mass spectrometry (GC × GC-TOF-MS). Comparison was made of the analyses using the different methods for the shared samples. The results were similar, thereby providing satisfactory confirmation of both similarly positive and negative findings. No pesticides were found in the organic-farmed samples. In samples from integrated pest management practices, nine pesticides were determined and confirmed to be present, ranging from 2 µg kg(-1) for fluazifop-p-butyl to 50 µg kg(-1) for fenpropathrin. Concentrations of residues in strawberries were less than European maximum residue limits.

An integrated strategy to improve data acquisition and metabolite identification by time-staggered ion lists in UHPLC/Q-TOF MS-based metabolomics.

PubMed

Wang, Yang; Feng, Ruibing; He, Chengwei; Su, Huanxing; Ma, Huan; Wan, Jian-Bo

2018-08-05

The narrow linear range and the limited scan time of the given ion make the quantification of the features challenging in liquid chromatography-mass spectrometry (LC-MS)-based untargeted metabolomics with the full-scan mode. And metabolite identification is another bottleneck of untargeted analysis owing to the difficulty of acquiring MS/MS information of most metabolites detected. In this study, an integrated workflow was proposed using the newly established multiple ion monitoring mode with time-staggered ion lists (tsMIM) and target-directed data-dependent acquisition with time-staggered ion lists (tsDDA) to improve data acquisition and metabolite identification in UHPLC/Q-TOF MS-based untargeted metabolomics. Compared to the conventional untargeted metabolomics, the proprosed workflow exhibited the better repeatability before and after data normalization. After selecting features with the significant change by statistical analysis, MS/MS information of all these features can be obtained by tsDDA analysis to facilitate metabolite identification. Using time-staggered ion lists, the workflow is more sensitive in data acquisition, especially for the low-abundant features. Moreover, the metabolites with low abundance tend to be wrongly integrated and triggered by full scan-based untargeted analysis with MS E acquisition mode, which can be greatly improved by the proposed workflow. The integrated workflow was also successfully applied to discover serum biosignatures for the genetic modification of fat-1 in mice, which indicated its practicability and great potential in future metabolomics studies. Copyright © 2018 Elsevier B.V. All rights reserved.

Practical approaches to the ESI-MS analysis of catalytic reactions.

PubMed

Yunker, Lars P E; Stoddard, Rhonda L; McIndoe, J Scott

2014-01-01

Electrospray ionization mass spectrometry (ESI-MS) is a soft ionization technique commonly coupled with liquid or gas chromatography for the identification of compounds in a one-time view of a mixture (for example, the resulting mixture generated by a synthesis). Over the past decade, Scott McIndoe and his research group at the University of Victoria have developed various methodologies to enhance the ability of ESI-MS to continuously monitor catalytic reactions as they proceed. The power, sensitivity and large dynamic range of ESI-MS have allowed for the refinement of several homogenous catalytic mechanisms and could potentially be applied to a wide range of reactions (catalytic or otherwise) for the determination of their mechanistic pathways. In this special feature article, some of the key challenges encountered and the adaptations employed to counter them are briefly reviewed. Copyright © 2014 John Wiley & Sons, Ltd.

Perceived time slows during fleeting fun or fear.

PubMed

Corke, Mike; Bell, Jason; Goodhew, Stephanie C; Smithson, Michael; Edwards, Mark

2018-02-01

Previous psychophysical studies at durations greater than 1000 ms have confirmed the anecdotal reports of an increase in the perceived duration of both positively and negatively valenced emotive stimuli; however, the results of studies at durations less than 1000 ms have been inconsistent. This study further investigated the effect of valence on the perception of durations less than 1000 ms. We used both positively and negatively valenced stimuli in order to compare their effects on the distortion of duration, and we tested multiple data points within the sub-one-second range. We found an increase in the perceived duration of both positively and negatively valenced emotional stimuli at all data points. This is consistent with studies at durations longer than 1000 ms and also with models of temporal processing. We also confirmed that Weber fractions, within the range tested, followed the generalized form of Weber's law.

Real-Time Assessment of Fatigue in Patients With Multiple Sclerosis: How Does It Relate to Commonly Used Self-Report Fatigue Questionnaires?

PubMed

Heine, Martin; van den Akker, Lizanne Eva; Blikman, Lyan; Hoekstra, Trynke; van Munster, Erik; Verschuren, Olaf; Visser-Meily, Anne; Kwakkel, Gert

2016-11-01

(1) To assess real-time patterns of fatigue; (2) to assess the association between a real-time fatigue score and 3 commonly used questionnaires (Checklist Individual Strength [CIS] fatigue subscale, Modified Fatigue Impact Scale (MFIS), and Fatigue Severity Scale [FSS]); and (3) to establish factors that confound the association between the real-time fatigue score and the conventional fatigue questionnaires in patients with multiple sclerosis (MS). Cross-sectional study. MS-specialized outpatient facility. Ambulant patients with MS (N=165) experiencing severe self-reported fatigue. Not applicable. A real-time fatigue score was assessed by sending participants 4 text messages on a particular day (How fatigued do you feel at this moment?; score range, 0-10). Latent class growth mixed modeling was used to determine diurnal patterns of fatigue. Regression analyses were used to assess the association between the mean real-time fatigue score and the CIS fatigue subscale, MFIS, and FSS. Significant associations were tested for candidate confounders (eg, disease severity, work status, sleepiness). Four significantly different fatigue profiles were identified by the real-time fatigue score, namely a stable high (n=79), increasing (n=57), stable low (n=16), and decreasing (n=13). The conventional questionnaires correlated poorly (r<.300) with the real-time fatigue score. The Epworth Sleepiness Scale significantly reduced the regression coefficient between the real-time fatigue score and conventional questionnaires, ranging from 15.4% to 35%. Perceived fatigue showed 4 different diurnal patterns in patients with MS. Severity of sleepiness is an important confounder to take into account in the assessment of fatigue. Copyright © 2016 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

MEG Evidence for Dynamic Amygdala Modulations by Gaze and Facial Emotions

PubMed Central

Dumas, Thibaud; Dubal, Stéphanie; Attal, Yohan; Chupin, Marie; Jouvent, Roland; Morel, Shasha; George, Nathalie

2013-01-01

Background Amygdala is a key brain region for face perception. While the role of amygdala in the perception of facial emotion and gaze has been extensively highlighted with fMRI, the unfolding in time of amydgala responses to emotional versus neutral faces with different gaze directions is scarcely known. Methodology/Principal Findings Here we addressed this question in healthy subjects using MEG combined with an original source imaging method based on individual amygdala volume segmentation and the localization of sources in the amygdala volume. We found an early peak of amygdala activity that was enhanced for fearful relative to neutral faces between 130 and 170 ms. The effect of emotion was again significant in a later time range (310–350 ms). Moreover, the amygdala response was greater for direct relative averted gaze between 190 and 350 ms, and this effect was selective of fearful faces in the right amygdala. Conclusion Altogether, our results show that the amygdala is involved in the processing and integration of emotion and gaze cues from faces in different time ranges, thus underlining its role in multiple stages of face perception. PMID:24040190

Quantification of isoflavones in coffee by using solid phase extraction (SPE) and high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS).

PubMed

Caprioli, Giovanni; Navarini, Luciano; Cortese, Manuela; Ricciutelli, Massimo; Torregiani, Elisabetta; Vittori, Sauro; Sagratini, Gianni

2016-09-01

A new method for extracting isoflavones from espresso coffee (EC) was coupled with high-performance liquid chromatography-tandem mass spectrometry (MS/MS) for the first time to analyse five isoflavones, which included both a glycosilated form, genistin and the aglycons daidzein, genistein, formononetin and biochanin A. Isoflavones were extracted from coffee samples using methanol, stored in a freezer overnight to precipitate proteic or lipidic residues and purified on SPE C18 cartridges before high-performance liquid chromatography-MS/MS analysis. The recovery percentages obtained by spiking the matrix at concentrations of 10 and 100 µg l(-1) with a standard mixture of isoflavones were in the range of 70 to 104%. The limits of detection and limits of quantification were in the range of 0.015-0.3 µg l(-1) and 0.05-1 µg l(-1) , respectively. Once validated, the method was used to analyze the concentrations of isoflavones in six ECs and ten ground coffee samples. Only formononetin and biochanin A were found, and their respective concentrations ranged from 0.36 to 0.41 µg l(-1) and from 0.58 to 3.26 µg l(-1) in ECs and from 0.36 to 4.27 µg kg(-1) and from 0.71 to 3.95 µg kg(-1) in ground coffees. This method confirms the high specificity and selectivity of MS/MS systems for detecting bioactives in complex matrices such as coffee.Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Screening Natural Content of Water-Soluble B Vitamins in Fish: Enzymatic Extraction, HILIC Separation, and Tandem Mass Spectrometric Determination.

PubMed

Chatterjee, Niladri Sekhar; Kumar, K Ashok; Ajeeshkumar, K K; Kumari, K R Remya; Vishnu, K V; Anandan, Rangasamy; Mathew, Suseela; Ravishankar, C N

2017-05-01

Despite the potential of LC with tandem MS (MS/MS) in improving sensitivity and selectivity, analytical methods are scarce for the determination of protein-bound and phosphorylated forms of B vitamins in food. This prompted us to develop a method for LC-MS/MS determination of naturally occurring nicotinamide, nicotinic acid, thiamine, pyridoxine, riboflavin, pantothenic acid, biotin, folic acid, and cyanocobalamin in fish. Baseline separation of the vitamins was achieved in a hydrophilic interaction LC condition. An ultrasonication-assisted enzymatic extraction protocol for sample preparation was optimized and validated. The time required for extraction was significantly reduced (to 4 h), while maintaining good extraction efficiency. Acetonitrile content (80%, v/v) in the prepared sample was found to be optimum for excellent peak shape and sensitivity. The dynamic linear range of the vitamins ranged from 2.5 to 500 ng/g, and the regression coefficient values were greater than 0.99. LOQ values ranged from 0.4 to 50 ng/g for the different vitamins. The spike recovery values at 50 and 100 ng/g ranged from 87.5 to 97.5%. The intra- and interday precision values were satisfactory. Accuracy of the developed method was determined by analysis of a Certified Reference Material. The method could also be used for unambiguous determination of the natural content of the target vitamins in fish.

Development and validation of a method for determination of corticosteroids in pig fat using liquid chromatography-tandem mass spectrometry.

PubMed

Tölgyesi, Adám; Sharma, Virender K; Fekete, Jeno

2011-02-15

A new method was developed to determine five corticosteroids (prednisolone, methylprednisone, flumethasone, dexamethasone, and methylprednisolone) in pig fat samples by liquid chromatography-tandem mass spectrometry (LC-MS/MS) utilizing an optimized liquid-liquid extraction (LLE) and subsequent solid-phase extraction (SPE) for sample clean-up. In the sample preparation, a pig fat sample was dissolved in n-hexane and then extracted into the methanol-water (50/50, v/v) mixture that enabled extraction of only medium polar corticosteroids and not the non-polar components of matrices. This extract was cleaned-up and concentrated on polymeric Oasis HLB SPE cartridge. Separation involved isocratic solvent (methanol-acetate buffer, pH 5.4) and Ascentis Express Fused-Core type HLPC column; reduced the analysis time to 7.5 min, which is at least two times lower than time required for separation using conventional techniques. Other advantage of the developed method is the minimized ion suppression of LC-MS/MS analysis, which allowed detection of corticosteroids in sub μg/kg. Method was validated according to European Union (EU) Commission Decision 2002/657/EC. Measured parameters such as selectivity, linearity, recovery, within-laboratory reproducibility, decision limit, and detection capability satisfied the EU Directive. Ranges of mean recoveries and within-laboratory reproducibility were 81-100% and 8.0-20.5%, respectively. Decision limits were calculated in the range from 4.5 to 11.9 μg/kg for MRL compounds and varied from 0.1 to 0.2 μg/kg for banned substances. Limit of detections (LODs), calculated as three time signal-to-noise ratio, were in the range of 0.1-0.3 μg/kg. Copyright © 2010 Elsevier B.V. All rights reserved.

MS-based monitoring of proteolytic decay of synthetic reporter peptides for quality control of plasma and serum specimens.

PubMed

Findeisen, Peter; Thumfart, Jörg Oliver; Costina, Victor; Hofheinz, Ralf; Neumaier, Michael

2013-09-01

To determine the preanalytical quality of serum and plasma by monitoring the time-dependent ex vivo decay of a synthetic reporter peptide (RP) with liquid chromatography/mass spectrometry (LC/MS). Serum and plasma specimens were spiked with the RP and proteolytic fragments were monitored with LC/MS at different preanalytical time points ranging from 2 to 24 hours after blood withdrawal. The concentration of fragments changed in a time-dependent manner, and respective peptide profiles were used to classify specimens according to their preanalytical time span. Classification accuracy was high, with values always above 0.89 for areas under receiver operating characteristic curves. This "proteomics degradation clock" can be used to estimate the preanalytical quality of serum and plasma and might have impact on quality control procedures of biobanking repositories.

The Effect of Leaf Stacking on Leaf Reflectance and Vegetation Indices Measured by Contact Probe during the Season

PubMed Central

Neuwirthová, Eva; Lhotáková, Zuzana; Albrechtová, Jana

2017-01-01

The aims of the study were: (i) to compare leaf reflectance in visible (VIS) (400–700 nm), near-infrared (NIR) (740–1140 nm) and short-wave infrared (SWIR) (2000–2400 nm) spectral ranges measured monthly by a contact probe on a single leaf and a stack of five leaves (measurement setup (MS)) of two broadleaved tree species during the vegetative season; and (ii) to test if and how selected vegetation indices differ under these two MS. In VIS, the pigment-related spectral region, the effect of MS on reflectance was negligible. The major influence of MS on reflectance was detected in NIR (up to 25%), the structure-related spectral range; and weaker effect in SWIR, the water-related spectral range. Vegetation indices involving VIS wavelengths were independent of MS while indices combining wavelengths from both VIS and NIR were MS-affected throughout the season. The effect of leaf stacking contributed to weakening the correlation between the leaf chlorophyll content and selected vegetation indices due to a higher leaf mass per area of the leaf sample. The majority of MS-affected indices were better correlated with chlorophyll content in both species in comparison with MS-unaffected indices. Therefore, in terms of monitoring leaf chlorophyll content using the contact probe reflectance measurement, these MS-affected indices should be used with caution, as discussed in the paper. If the vegetation indices are used for assessment of plant physiological status in various times of the vegetative season, then it is essential to take into consideration their possible changes induced by the particular contact probe measurement setup regarding the leaf stacking. PMID:28538685

One step derivatization with British Anti-Lewsite in combination with gas chromatography coupled to triple-quadrupole tandem mass spectrometry for the fast and selective analysis of inorganic arsenic in rice.

PubMed

Kang, Ju Hui; Jung, Hyun Jeong; Jung, Mun Yhung

2016-08-31

We developed a new fast and selective analytical method for the determination of inorganic arsenic (iAs) in rice by a gas chromatography - tandem mass spectrometry (GC-MS/MS) in combination with one step derivatization of inorganic arsenic (iAs) with British Anti-Lewsite (BAL). Two step derivatization of iAs with BAL has been previously performed for the GC-MS analysis. In this paper, the quantitative one step derivatization condition was successfully established. The GC-MS/MS was carried out with a short nonpolar capillary column (0.25 mm × 10 m) under the conditions of fast oven temperature ramp rate (4 °C/s) and high linear velocity (108.8 cm/s) of the carrier gas. The established GC-MS/MS method showed an excellent linearity (r(2) > 0.999) in a tested range (0.2-100.0 μg L(-1)), ultra-low limit of detection (LOD, 0.08 pg), and high precision and accuracy. The GC-MS/MS technique showed far greater selectivity (22.5 fold higher signal to noise ratio in rice sample) on iAs than GC-MS method. The gas chromatographic running time was only 2.5 min with the iAs retention time of 1.98 min. The established method was successfully applied to quantify the iAs contents in polished rice. The mean iAs content in the Korean polished rice (n = 27) was 66.1 μg kg(-1) with the range of 37.5-125.0 μg kg(-1). This represents the first report on the GC-tandem mass spectrometry in combination with the one step derivatization with BAL for the iAs speciation in rice. This GC-MS/MS method would be a simple, useful and reliable measure for the iAs analysis in rice in the laboratories in which the expensive and element specific HPLC-ICP-MS is not available. Copyright © 2016 Elsevier B.V. All rights reserved.

Quasi-dynamic mode of nanomembranes for time-of-flight mass spectrometry of proteins.

PubMed

Park, Jonghoo; Kim, Hyunseok; Blick, Robert H

2012-04-21

Mechanical resonators realized on the nano-scale by now offer applications in mass-sensing of biomolecules with extraordinary sensitivity. The general idea is that perfect mechanical biosensors should be of extremely small size to achieve zeptogram sensitivity in weighing single molecules similar to a balance. However, the small scale and long response time of weighing biomolecules with a cantilever restrict their usefulness as a high-throughput method. Commercial mass spectrometry (MS) such as electro-spray ionization (ESI)-MS and matrix-assisted laser desorption/ionization (MALDI)-time of flight (TOF)-MS are the gold standards to which nanomechanical resonators have to live up to. These two methods rely on the ionization and acceleration of biomolecules and the following ion detection after a mass selection step, such as time-of-flight (TOF). Hence, the spectrum is typically represented in m/z, i.e. the mass to ionization charge ratio. Here, we describe the feasibility and mass range of detection of a new mechanical approach for ion detection in time-of-flight mass spectrometry, the principle of which is that the impinging ion packets excite mechanical oscillations in a silicon nitride nanomembrane. These mechanical oscillations are henceforth detected via field emission of electrons from the nanomembrane. Ion detection is demonstrated in MALDI-TOF analysis over a broad range with angiotensin, bovine serum albumin (BSA), and an equimolar protein mixture of insulin, BSA, and immunoglobulin G (IgG). We find an unprecedented mass range of operation of the nanomembrane detector.

Role of carbon nano-materials in the analysis of biological materials by laser desorption/ionization-mass spectrometry.

PubMed

Najam-ul-Haq, M; Rainer, M; Szabó, Z; Vallant, R; Huck, C W; Bonn, G K

2007-03-10

At present, carbon nano-materials are being utilized in various procedures, especially in laser desorption/ionization-mass spectrometry (LDI-MS) for analyzing a range of analytes, which include peptides, proteins, metabolites, and polymers. Matrix-oriented LDI-MS techniques are very well established, with weak organic acids as energy-absorbing substances. Carbon materials, such as nano-tubes and fullerenes are being successfully applied in the small-mass range, where routine matrices have strong background signals. In addition, the role of carbon nano-materials is very well established in the fractionation and purification fields. Modified diamond powder and surfaces are utilized in binding peptides and proteins from complex biological fluids and analyzed by matrix-assisted laser desorption/ionization (MALDI) time-of-flight (TOF) mass spectrometry (MS). Polylysine-coated diamond is used for solid-phase extraction to pre-concentrate DNA oligonucleotides. Graphite is useful for desalting, pre-concentration, and as energy-absorbing material (matrix) in desorption/ionization. Carbon nano-tubes in their different derivatized forms are used as matrix materials for the analysis of a range of analytes, such as carbohydrates, amino acids, peptides, proteins, and some environmental samples by LDI-MS. Fullerenes are modified in different ways to bind serum entities analyzed through MALDI/TOF-MS and are subsequently utilized in their identifications. In addition, the fullerenes are a promising matrix in LDI-MS, but improvements are needed.

Delay of cognitive gamma responses in Alzheimer's disease

PubMed Central

Başar, Erol; Emek-Savaş, Derya Durusu; Güntekin, Bahar; Yener, Görsev G.

2016-01-01

Event-related oscillations (EROs) reflect cognitive brain dynamics, while sensory-evoked oscillations (SEOs) reflect sensory activities. Previous reports from our lab have shown that those with Alzheimer's disease (AD) or mild cognitive impairment (MCI) have decreased activity and/or coherence in delta, theta, alpha and beta cognitive responses. In the current study, we investigated gamma responses in visual SEO and ERO in 15 patients with AD and in 15 age-, gender- and education-matched healthy controls. The following parameters were analyzed over the parietal-occipital regions in both groups: (i) latency of the maximum gamma response over a 0–800 ms time window; (ii) the maximum peak-to-peak amplitudes for each participant's averaged SEO and ERO gamma responses in 3 frequency ranges (25–30, 30–35, 40–48 Hz); and (iii) the maximum peak-to-peak amplitudes for each participant's averaged SEO and ERO gamma responses over a 0–800 ms time block containing four divided time windows (0–200, 200–400, 400–600, and 600–800 ms). There were main group effects in terms of both latency and peak-to-peak amplitudes of gamma ERO. However, peak-to-peak gamma ERO amplitude differences became noticeable only when the time block was divided into four time windows. SEO amplitudes in the 25–30 Hz frequency range of the 0–200 ms time window over the left hemisphere were greater in the healthy controls than in those with AD. Gamma target ERO latency was delayed up to 138 ms in AD patients when compared to healthy controls. This finding may be an effect of lagged neural signaling in cognitive circuits, which is reflected by the delayed gamma responses in those with AD. Based on the results of this study, we propose that gamma responses should be examined in a more detailed fashion using multiple frequency and time windows. PMID:26937378

Determination of alkylphenols in water samples using liquid chromatography-tandem mass spectrometry after pre-column derivatization with dansyl chloride.

PubMed

Pernica, Marek; Poloucká, Petra; Seifertová, Marta; Šimek, Zdeněk

2015-10-23

The present study describes an effect of reaction condition of pre-column derivatization of alkylphenols (APs): bisphenol A (BPA), 4-tert-octylphenol (4-t-OP), 4-octylphenol (4-OP), 4-n-nonylphenol (4-n-NP), and isomers of 4-nonylphenol (iso-NP) with 5-(dimethylamino) naphthalene-1-sulfonyl chloride (dansyl chloride, DNSC) on their LC-ESI-MS/MS determination in water samples. Chemical derivatization improves the sensitivity and selectivity of LC-MS/MS analysis. In principle, alkylphenols can be analyzed by LC-MS/MS without derivatization. However, pre-column derivatization of APs increases the sensitivity up to 1000 times in comparison with the analysis of underivatized alkylphenols. Reaction conditions affecting formation of the DNSC-derivatives, such as various solvent, reaction temperature, reaction time, DNSC concentration and pH values were tested. The most suitable conditions, in terms of achieving a high sensitivity, resulting from this study are: acetonitrile as reaction solvent, 60 min as reaction time, 60 °C as reaction temperature, pH values 10.5, 0.5 mg mL(-1) as DNSC concentration. Calibration curves are linear at least in the range of 1-1000 ng mL(-1), limits of detection (LOD) and limits of quantification (LOQ) ranging from 0.02 to 0.25 pg/injection and from 0.08 to 0.83 pg/injection, respectively. The improved procedure was successfully applied for the analysis of APs and BPA in real water samples. The median concentration of BPA and iso-NP obtained in bottled waters was 4.7 ng L(-1) and 33.5 ng L(-1), respectively. The median concentration of 4-t-OP was 1.3 ng L(-1.) Copyright © 2015 Elsevier B.V. All rights reserved.

Utilisation of an enzyme-linked immunosorbent assay (ELISA) for determination of alkylphenols in various environmental matrices. Comparison with LC-MS/MS method.

PubMed

Pasquet, Camille; Vulliet, Emmanuelle

2011-10-15

Among the wide range of substances discharged continuously in the environment, alkylphenols became a major focus of environmental research in the last decades, as it was found that they possess endocrine disrupting properties. Knowledge about the occurrence and levels of alkylphenols in environment is critical for the risk assessment of these compounds on both ecosystem and human health. However, the analysis of traces of alkylphenols in environmental matrices is a very difficult task, and the suitable methods involve generally an extraction followed by an extensive sample clean-up before detection, steps often time-consuming and costly. In order to reduce the analysis time, obtain a high throughput of analysis and thus improve work efficiency, the objective of the present study is to investigate the use of immunochemical technique (ELISA) for the determination of nonylphenol and octylphenol in soils and various kinds of water. To our knowledge, this is the first time that the determination of alkylphenols in soil using immunoassay technique is described. A methodology is developed, based on the combination of a single preparation step and the use of a simply ELISA kit. The performances of the method are compared with LC-MS/MS, considered as reference. The developed procedure offers the sensitivity and selectivity necessary for the detection of the target alkylphenols in the ng/g or ng/L range, and is successfully applied to the analysis of several samples. Results indicate that alkylphenols are quantified with concentrations in the same order than LC-MS/MS, meaning that ELISA may be useful not only in screening the samples and get a positive/negative response, but also it allows a good approximation of the concentrations. Copyright © 2011 Elsevier B.V. All rights reserved.

Determination of Urinary PAH Metabolites Using DLLME Hyphenated to Injector Port Silylation and GC-MS-MS.

PubMed

Gupta, Manoj Kumar; Jain, Rajeev; Singh, Pratibha; Ch, Ratnasekhar; Mudiam, Mohana Krishna Reddy

2015-06-01

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental pollutants and well-known carcinogens. Hydroxy derivatives of PAH are considered as biomarkers of PAH exposure, and there is a need to measure these metabolites at low concentrations. So, a precise and eco-friendly analytical method has been developed for rapid determination of PAH metabolites. For the first time, a new analytical method based on coupling of dispersive liquid-liquid microextraction (DLLME) with auto-injector port silylation (auto-IPS) followed by gas chromatography-tandem mass spectrometry (GC-MS-MS) analysis is reported for the analysis of seven urinary PAH metabolites. Factors affecting DLLME and IPS, such as type and volume of extraction and disperser solvent, pH, ionic strength, injector port temperature, volume of N,O-bis(trimethylsilyl)trifluoroacetamide and type of solvent were investigated. Under optimized conditions, the limit of detection and limit of quantification were found to be in the range of 1-9 and 3-29 ng/mL, respectively. Satisfactory recoveries of metabolites in urine samples in the range of 87-95% were found. The developed method has been successfully applied for the determination of PAH metabolites in urine samples of exposed workers. DLLME-auto-IPS-GC-MS-MS method is time, labor, solvent and reagent saving, which can be routinely used for the analysis of urinary PAH metabolites. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Improving signal-to-noise ratios of liquid chromatography-tandem mass spectrometry peaks using noise frequency spectrum modification between two consecutive matched-filtering procedures.

PubMed

Wang, Shau-Chun; Huang, Chih-Min; Chiang, Shu-Min

2007-08-17

This paper reports a simple chemometric technique to alter the noise spectrum of liquid chromatography-tandem mass spectrometry (LC-MS-MS) chromatogram between two consecutive matched filter procedures to improve the peak signal-to-noise (S/N) ratio enhancement. This technique is to multiply one match-filtered LC-MS-MS chromatogram with another artificial chromatogram added with thermal noises prior to the second matched filter. Because matched filter cannot eliminate low-frequency components inherent in the flicker noises of spike-like sharp peaks randomly riding on LC-MS-MS chromatograms, efficient peak S/N ratio improvement cannot be accomplished using one-step or consecutive matched filter procedures to process LC-MS-MS chromatograms. In contrast, when the match-filtered LC-MS-MS chromatogram is conditioned with the multiplication alteration prior to the second matched filter, much better efficient ratio improvement is achieved. The noise frequency spectrum of match-filtered chromatogram, which originally contains only low-frequency components, is altered to span a boarder range with multiplication operation. When the frequency range of this modified noise spectrum shifts toward higher frequency regime, the second matched filter, working as a low-pass filter, is able to provide better filtering efficiency to obtain higher peak S/N ratios. Real LC-MS-MS chromatograms containing random spike-like peaks, of which peak S/N ratio improvement is less than four times with two consecutive matched filters typically, are remedied to accomplish much better ratio enhancement approximately 16-folds when the noise frequency spectrum is modified between two matched filters.

Determination of selected non-authorized insecticides in peppers by liquid chromatography time-of-flight mass spectrometry and tandem mass spectrometry.

PubMed

Mezcua, Milagros; Ferrer, Carmen; García-Reyes, Juan F; Martínez-Bueno, María Jesús; Albarracín, Micaela; Claret, María; Fernández-Alba, Amadeo R

2008-05-01

In this work, two analytical methods based on liquid chromatography coupled to electrospray time-of-flight mass spectrometry (LC/ESI-TOFMS) and tandem mass spectrometry (LC/ESI-MS/MS) are described for the identification, confirmation and quantitation of three insecticides non-authorized in the European Union (nitenpyram, isocarbophos and isofenphos-methyl) but detected in recent monitoring programmes in pepper samples. The proposed methodologies involved a sample extraction procedure using liquid-liquid partition with acetonitrile followed by a cleanup step based on dispersive solid-phase extraction. Recovery studies performed on peppers spiked at different fortification levels (10 and 50 microg kg(-1)) yielded average recoveries in the range 76-100% with relative standard deviation (RSD) (%) values below 10%. Identification, confirmation and quantitation were carried out by LC/TOFMS and LC/MS/MS using a hybrid triple quadrupole linear ion trap (QqLIT) instrument in multiple-reaction monitoring (MRM) mode. The obtained limits of quantitation (LOQs) were in the range 0.1-5 microg kg(-1), depending on each individual technique. Finally, the proposed methods were successfully applied to the analysis of suspected pepper samples. Copyright (c) 2008 John Wiley & Sons, Ltd.

Solvent Separating Secondary Metabolites Directly from Biosynthetic Tissue for Surface-Assisted Laser Desorption Ionisation Mass Spectrometry

PubMed Central

Rudd, David; Benkendorff, Kirsten; Voelcker, Nicolas H.

2015-01-01

Marine bioactive metabolites are often heterogeneously expressed in tissues both spatially and over time. Therefore, traditional solvent extraction methods benefit from an understanding of the in situ sites of biosynthesis and storage to deal with heterogeneity and maximize yield. Recently, surface-assisted mass spectrometry (MS) methods namely nanostructure-assisted laser desorption ionisation (NALDI) and desorption ionisation on porous silicon (DIOS) surfaces have been developed to enable the direct detection of low molecular weight metabolites. Since direct tissue NALDI-MS or DIOS-MS produce complex spectra due to the wide variety of other metabolites and fragments present in the low mass range, we report here the use of “on surface” solvent separation directly from mollusc tissue onto nanostructured surfaces for MS analysis, as a mechanism for simplifying data annotation and detecting possible artefacts from compound delocalization during the preparative steps. Water, ethanol, chloroform and hexane selectively extracted a range of choline esters, brominated indoles and lipids from Dicathais orbita hypobranchial tissue imprints. These compounds could be quantified on the nanostructured surfaces by comparison to standard curves generated from the pure compounds. Surface-assisted MS could have broad utility for detecting a broad range of secondary metabolites in complex marine tissue samples. PMID:25786067

HPLC-MS/MS method optimisation for matrix metalloproteinase 3 and matrix metalloproteinase 9 determination in human blood serum using target analysis.

PubMed

Kotnik, Petra; Krajnc, Metka Koren; Pahor, Artur; Finšgar, Matjaž; Knez, Željko

2018-02-20

A quantitative analysis of zinc endopeptidases matrix metalloproteinase 9 (MMP9) and matrix metalloproteinase 3 (MMP3) from human blood serum are presented. Both matrix metalloproteinases (MMP) are present in human blood serum and can be used as biomarkers for different diseases. The analysis was performed using LC-MS/MS with a triple quadrupole mass spectrometer, based on two specific peptides of each MMP in comparison with an enzyme-linked immunosorbent assay (ELISA). While the conditions for the LC-MS/MS analysis of MMP9 peptides were previously reported for bronchoalveolar lavage fluid, the analysis of MMP3 peptides was newly quantified for human blood serum herein for the first time. For MMP3, the linear behaviour was determined in the concentration range from 1.0-200.0ng/mL (R 2 =0.997) with an LLOD of 0.5ng/mL. For MMP9, linearity was determined in the concentration range from 6.5-65.0ng/mL (R 2 =0.995) with an LLOD of 2.0ng/mL. Copyright © 2017 Elsevier B.V. All rights reserved.

Development of a Molecular Tagging Velocimetry Technique for Non-Intrusive Velocity Measurements in Low-Speed Gas Flows

NASA Technical Reports Server (NTRS)

Andre, M. A.; Bardet, P. M.; Cadell, S. R.; Woods, B.; Burns, R. A.; Danehy, P. M.

2017-01-01

N2O molecular tagging velocimetry (N2O-MTV) is developed for use in very-high-temperature reactor environments. Tests were carried out to determine the optimum excitation wavelength, tracer concentration, and timing parameters for the laser system. Using NO tracers obtained from photo-dissociation of N2O, velocity profiles are successfully obtained in air, nitrogen, and helium for a large range of parameters: temperature from 295 to 781 K, pressure from 1 to 3 bars, with a velocity precision of 0.01 m/s. Furthermore, by using two read pulses at adjustable time delays, the velocity dynamic range can be increased. An unprecedented dynamic range of 5,000 has been obtained to successfully resolve the flow during a helium blowdown from 1000 m/s down to 0.2 m/s. This technique is also applied to the high-temperature test facility (HTTF) at Oregon State University (OSU) during a depressurized condition cooldown (DCC) event. Details of these measurements are presented in a companion paper. This technique shows a strong potential for fundamental understanding of gas flows in nuclear reactors and to provide benchmark experimental data to validate numerical simulations.

Arterial spin-labeling assessment of normalized vascular intratumoral signal intensity as a predictor of histologic grade of astrocytic neoplasms.

PubMed

Furtner, J; Schöpf, V; Schewzow, K; Kasprian, G; Weber, M; Woitek, R; Asenbaum, U; Preusser, M; Marosi, C; Hainfellner, J A; Widhalm, G; Wolfsberger, S; Prayer, D

2014-03-01

Pulsed arterial spin-labeling is a noninvasive MR imaging perfusion method performed with the use of water in the arterial blood as an endogenous contrast agent. The purpose of this study was to determine the inversion time with the largest difference in normalized intratumoral signal intensity between high-grade and low-grade astrocytomas. Thirty-three patients with gliomas, histologically classified as low-grade (n = 7) or high-grade astrocytomas (n = 26) according to the World Health Organization brain tumor classification, were included. A 3T MR scanner was used to perform pulsed arterial spin-labeling measurements at 8 different inversion times (370 ms, 614 ms, 864 ms, 1114 ms, 1364 ms, 1614 ms, 1864 ms, and 2114 ms). Normalized intratumoral signal intensity was calculated, which was defined by the signal intensity ratio of the tumor and the contralateral normal brain tissue for all fixed inversion times. A 3-way mixed ANOVA was used to reveal potential differences in the normalized vascular intratumoral signal intensity between high-grade and low-grade astrocytomas. The difference in normalized vascular intratumoral signal intensity between high-grade and low-grade astrocytomas obtained the most statistically significant results at 370 ms (P = .003, other P values ranged from .012-.955). The inversion time by which to differentiate high-grade and low-grade astrocytomas by use of normalized vascular intratumoral signal intensity was 370 ms in our study. The normalized vascular intratumoral signal intensity values at this inversion time mainly reflect the labeled intra-arterial blood bolus and therefore could be referred to as normalized vascular intratumoral signal intensity. Our data indicate that the use of normalized vascular intratumoral signal intensity values allows differentiation between low-grade and high-grade astrocytomas and thus may serve as a new, noninvasive marker for astrocytoma grading.

Feasibility of through-time spiral generalized autocalibrating partial parallel acquisition for low latency accelerated real-time MRI of speech.

PubMed

Lingala, Sajan Goud; Zhu, Yinghua; Lim, Yongwan; Toutios, Asterios; Ji, Yunhua; Lo, Wei-Ching; Seiberlich, Nicole; Narayanan, Shrikanth; Nayak, Krishna S

2017-12-01

To evaluate the feasibility of through-time spiral generalized autocalibrating partial parallel acquisition (GRAPPA) for low-latency accelerated real-time MRI of speech. Through-time spiral GRAPPA (spiral GRAPPA), a fast linear reconstruction method, is applied to spiral (k-t) data acquired from an eight-channel custom upper-airway coil. Fully sampled data were retrospectively down-sampled to evaluate spiral GRAPPA at undersampling factors R = 2 to 6. Pseudo-golden-angle spiral acquisitions were used for prospective studies. Three subjects were imaged while performing a range of speech tasks that involved rapid articulator movements, including fluent speech and beat-boxing. Spiral GRAPPA was compared with view sharing, and a parallel imaging and compressed sensing (PI-CS) method. Spiral GRAPPA captured spatiotemporal dynamics of vocal tract articulators at undersampling factors ≤4. Spiral GRAPPA at 18 ms/frame and 2.4 mm 2 /pixel outperformed view sharing in depicting rapidly moving articulators. Spiral GRAPPA and PI-CS provided equivalent temporal fidelity. Reconstruction latency per frame was 14 ms for view sharing and 116 ms for spiral GRAPPA, using a single processor. Spiral GRAPPA kept up with the MRI data rate of 18ms/frame with eight processors. PI-CS required 17 minutes to reconstruct 5 seconds of dynamic data. Spiral GRAPPA enabled 4-fold accelerated real-time MRI of speech with a low reconstruction latency. This approach is applicable to wide range of speech RT-MRI experiments that benefit from real-time feedback while visualizing rapid articulator movement. Magn Reson Med 78:2275-2282, 2017. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

Balloon Valvuloplasty of Tricuspid Stenosis: A Retrospective Study of 5 Labrador Retriever Dogs.

PubMed

Lake-Bakaar, G A; Griffiths, L G; Kittleson, M D

2017-03-01

There are limited reports of severe tricuspid valve stenosis in dogs and limited data regarding treatment and outcome. To evaluate clinical signs, echocardiographic features, and outcome of balloon valvuloplasty (BV) in dogs with severe tricuspid valve stenosis (TVS) in which BV was attempted. Five client-owned dogs with severe TVS. Records were retrospectively reviewed and data collected regarding signalment, clinical signs, diagnostic findings, procedures, and outcome. All dogs were Labrador Retrievers. Presenting complaints included episodic weakness/syncope (4/5), abdominal distension (4/5), lethargy (2/5), and exercise intolerance (2/5). The median and range of measurements before BV were as follows: TV mean velocity 1.5 m/s (range 1.4-1.7 m/s); velocity-time integral (VTI) 79.8 cm (42.4-99.1 cm); and TV maximum velocity 2.9 m/s (2.3-3.2 m/s). Measurements (available for 3 of 5 dogs) after BV were as follows: TV mean velocity 1.15 m/s (0.9-1.4 m/s); VTI 44.95 cm (41.4-54.8 cm); and TV maximum velocity 1.15 m/s (1.9-2.3 m/s). The procedure was attempted in all dogs and completed in 4/5 dogs. The largest balloon diameter ranged from 15 mm to 25 mm, and length ranged from 4 cm to 5 cm. Right atrial pressure decreased in 4/5 dogs. All but 1 dog had clinical improvement after BV, but recurrence of clinical signs occurred (2/5). Tricuspid regurgitation worsened in 1 dog culminating in right heart failure and euthanasia. BV can be an effective treatment; however, clinical signs can recur. Right heart failure due to worsened TR is a potential complication in dogs with pre-existing moderate-to-severe TR. Copyright © 2017 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.

A novel isoflavone profiling method based on UPLC-PDA-ESI-MS.

PubMed

Zhang, Shuang; Zheng, Zong-Ping; Zeng, Mao-Mao; He, Zhi-Yong; Tao, Guan-Jun; Qin, Fang; Chen, Jie

2017-03-15

A novel non-targeted isoflavone profiling method was developed using the diagnostic fragment-ion-based extension strategy, based on ultra-high performance liquid chromatography coupled with photo-diode array detector and electrospray ionization-mass spectrometry (UPLC-PDA-ESI-MS). 16 types of isoflavones were obtained in positive mode, but only 12 were obtained in negative mode due to the absence of precursor ions. Malonyldaidzin and malonylgenistin glycosylated at the 4'-O position or malonylated at the 4″-O position of glucose were indicated by their retention behavior and fragmentation pattern. Three possible quantification methods in one run based on UPLC-PDA and UPLC-ESI-MS were validated and compared, suggesting that methods based on UPLC-ESI-MS possess remarkable selectivity and sensitivity. Impermissible quantitative deviations induced by the linearity calibration with 400-fold dynamic range was observed for the first time and was recalibrated with a 20-fold dynamic range. These results suggest that isoflavones and their stereoisomers can be simultaneously determined by positive-ion UPLC-ESI-MS in soymilk. Copyright © 2016. Published by Elsevier Ltd.

Prototype of the gas chromatograph - mass spectrometer to investigate volatile species in the lunar soil for the Luna-Glob and Luna-Resurs missions.

NASA Astrophysics Data System (ADS)

Hofer, L.; Lasi, D.; Tulej, M.; Wurz, P.; Cabane, M.; Cosica, D.; Gerasimov, M.; Rodinov, D.

2013-09-01

In preparation for the Russian Luna-Glob and Luna-Resurs missions we combined our compact time-offlight mass spectrometer (TOF-MS) with a chemical pre-separation of the species by gas chromatography (GC). Combined measurements with both instruments were successfully performed with the laboratory prototype of the mass spectrometer and a flight-like gas chromatograph. Due to its capability to record mass spectra over the full mass range at once with high sensitivity and a dynamic range of up to 106 within 1s, the TOF-MS system is a valuable extension of the GC analysis. The combined GC-MS complex is able to detect concentrations of volatile species in the sample of about 2·10^-9 by mass.

Assessing direct analysis in real-time-mass spectrometry (DART-MS) for the rapid identification of additives in food packaging.

PubMed

Ackerman, L K; Noonan, G O; Begley, T H

2009-12-01

The ambient ionization technique direct analysis in real time (DART) was characterized and evaluated for the screening of food packaging for the presence of packaging additives using a benchtop mass spectrometer (MS). Approximate optimum conditions were determined for 13 common food-packaging additives, including plasticizers, anti-oxidants, colorants, grease-proofers, and ultraviolet light stabilizers. Method sensitivity and linearity were evaluated using solutions and characterized polymer samples. Additionally, the response of a model additive (di-ethyl-hexyl-phthalate) was examined across a range of sample positions, DART, and MS conditions (temperature, voltage and helium flow). Under optimal conditions, molecular ion (M+H+) was the major ion for most additives. Additive responses were highly sensitive to sample and DART source orientation, as well as to DART flow rates, temperatures, and MS inlet voltages, respectively. DART-MS response was neither consistently linear nor quantitative in this setting, and sensitivity varied by additive. All additives studied were rapidly identified in multiple food-packaging materials by DART-MS/MS, suggesting this technique can be used to screen food packaging rapidly. However, method sensitivity and quantitation requires further study and improvement.

Enantiomeric separation and quantification of R/S-amphetamine in urine by ultra-high performance supercritical fluid chromatography tandem mass spectrometry.

PubMed

Hegstad, S; Havnen, H; Helland, A; Spigset, O; Frost, J

2018-03-01

To distinguish between legal and illegal consumption of amphetamine reliable analytical methods for chiral separation of the R- and S-enantiomers of amphetamine in biological specimens are required. In this regard, supercritical fluid chromatography (SFC) has several potential advantages over liquid chromatography, including rapid separation of enantiomers due to low viscosity and high diffusivity of supercritical carbon dioxide, the main component in the SFC mobile phase. A method for enantiomeric separation and quantification of R- and S-amphetamine in urine was developed and validated using ultra-high performance supercritical fluid chromatography-tandem mass spectrometry (UHPSFC-MS/MS). Sample preparation prior to UHPSFC-MS/MS analysis was a semi-automatic solid phase extraction method. The UHPSFC-MS/MS method used a Chiralpak AD-3 column with a mobile phase consisting of CO 2 and 0.2% cyclohexylamine in 2-propanol. The injection volume was 2 μL and run-time was 6 min. MS/MS detection was performed with positive electrospray ionization and two multiple reaction monitoring transitions (m/z 136.1 > 119.0 and m/z 136.1 > 91.0). The calibration range was 50-10,000 ng/mL for each enantiomer. The between-assay relative standard deviations were in the range of 3.7-7.6%. Recovery was 92-93% and matrix effects ranged from 100 to 104% corrected with internal standard. After development and validation, the method has been successfully implemented in routine use at our laboratory for both separation and quantification of R/S-amphetamine, and has proved to be a reliable and useful tool for distinguishing intake of R- and S-amphetamine in authentic patient samples. Copyright © 2018 Elsevier B.V. All rights reserved.

Broad-Range PCR Coupled with Electrospray Ionization Time of Flight Mass Spectrometry for Detection of Bacteremia and Fungemia in Patients with Neutropenic Fever.

PubMed

Desmet, S; Maertens, J; Bueselinck, K; Lagrou, K

2016-10-01

Infection is an important complication in patients with hematologic malignancies or solid tumors undergoing intensive cytotoxic chemotherapy. In only 20 to 30% of the febrile neutropenic episodes, an infectious agent is detected by conventional cultures. In this prospective study, the performance of broad-range PCR coupled with electrospray ionization time of flight mass spectrometry (PCR/ESI-MS) technology was compared to conventional blood cultures (BC) in a consecutive series of samples from high-risk hematology patients. In 74 patients, BC and a whole-blood sample for PCR/ESI-MS (Iridica BAC BSI; Abbott, Carlsbad, CA, USA) were collected at the start of each febrile neutropenic episode and, in case of persistent fever, also at day 5. During 100 different febrile episodes, 105 blood samples were collected and analyzed by PCR/ESI-MS. There was evidence of a bloodstream infection (BSI) in 36/105 cases (34%), based on 14 cases with both PCR/ESI-MS and BC positivity, 17 cases with BC positivity only, and 5 cases with PCR/ESI-MS positivity only. The sensitivity of PCR/ESI-MS was 45%, specificity was 93%, and the negative predictive value was 80% compared to blood culture. PCR/ESI-MS detected definite pathogens (Fusobacterium nucleatum and Streptococcus pneumoniae) missed by BC, whereas it missed both Gram-negative and Gram-positive organisms detected by BC. PCR/ESI-MS testing detected additional microorganisms but showed a low sensitivity (45%) compared to BC in neutropenic patients. Our results indicate a lower concordance between BC and PCR/ESI-MS in the neutropenic population than what has been previously reported in other patient groups with normal white blood cell distribution, and a lower sensitivity than other PCR-based methods. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

SprayQc: a real-time LC-MS/MS quality monitoring system to maximize uptime using off the shelf components.

PubMed

Scheltema, Richard A; Mann, Matthias

2012-06-01

With the advent of high-throughput mass spectrometry (MS)-based proteomics, the magnitude and complexity of the performed experiments has increased dramatically. Likewise, investments in chromatographic and MS instrumentation are a large proportion of the budget of proteomics laboratories. Guarding measurement quality and maximizing uptime of the LC-MS/MS systems therefore requires constant care despite automated workflows. We describe a real-time surveillance system, called SprayQc, that continuously monitors the status of the peripheral equipment to ensure that operational parameters are within an acceptable range. SprayQc is composed of multiple plug-in software components that use computer vision to analyze electrospray conditions, monitor the chromatographic device for stable backpressure, interact with a column oven to control pressure by temperature, and ensure that the mass spectrometer is still acquiring data. Action is taken when a failure condition has been detected, such as stopping the column oven and the LC flow, as well as automatically notifying the appropriate operator. Additionally, all defined metrics can be recorded synchronized on retention time with the MS acquisition file, allowing for later inspection and providing valuable information for optimization. SprayQc has been extensively tested in our laboratory, supports third-party plug-in development, and is freely available for download from http://sourceforge.org/projects/sprayqc .

Simultaneous Analysis of Iridoid Glycosides and Anthraquinones in Morinda officinalis Using UPLC-QqQ-MS/MS and UPLC-Q/TOF-MSE.

PubMed

Zhao, Xiangsheng; Wei, Jianhe; Yang, Meihua

2018-05-03

Morinda officinalis is an important herbal medicine and functional food, and its main constituents include anthraquinone and iridoid glycosides. Quantification of the main compounds is a necessary step to understand the quality and therapeutic properties of M. officinalis , but this has not yet been performed based on liquid chromatography/tandem mass spectrometry (LC-MS/MS). Analytes were extracted from M. officinalis by reflux method. Ultrahigh-performance liquid chromatography coupled with a triple quadrupole mass spectrometry (UPLC-QqQ-MS) using multiple reaction monitoring (MRM) mode was applied for quantification. Fragmentation pathways of deacetyl asperulosidic acid and rubiadin were investigated based on UPLC with quadrupole time-of-flight tandem mass spectrometry (Q/TOF-MS) in the MS E centroid mode. The method showed a good linearity over a wide concentration range (R² ≥ 0.9930). The limits of quantification of six compounds ranged from 2.6 to 27.57 ng/mL. The intra- and inter-day precisions of the investigated components exhibited an RSD within 4.5% with mean recovery rates of 95.32⁻99.86%. Contents of selected compounds in M. officinalis varied significantly depending on region. The fragmentation pathway of deacetyl asperulosidic and rubiadin was proposed. A selective and sensitive method was developed for determining six target compounds in M. officinalis by UPLC-MS/MS. Furthermore, the proposed method will be helpful for quality control and identification main compounds of M. officinalis .

Trace-Level Volatile Quantitation by Direct Analysis in Real Time Mass Spectrometry following Headspace Extraction: Optimization and Validation in Grapes.

PubMed

Jastrzembski, Jillian A; Bee, Madeleine Y; Sacks, Gavin L

2017-10-25

Ambient ionization mass spectrometric (AI-MS) techniques like direct analysis in real time (DART) offer the potential for rapid quantitative analyses of trace volatiles in food matrices, but performance is generally limited by the lack of preconcentration and extraction steps. The sensitivity and selectivity of AI-MS approaches can be improved through solid-phase microextraction (SPME) with appropriate thin-film geometries, for example, solid-phase mesh-enhanced sorption from headspace (SPMESH). This work improves the SPMESH-DART-MS approach for use in food analyses and validates the approach for trace volatile analysis for two compounds in real samples (grape macerates). SPMESH units prepared with different sorbent coatings were evaluated for their ability to extract a range of odor-active volatiles, with poly(dimethylsiloxane)/divinylbenzene giving the most satisfactory results. In combination with high-resolution mass spectrometry (HRMS), detection limits for SPMESH-DART-MS under 4 ng/L in less than 30 s acquisition times could be achieved for some volatiles [3-isobutyl-2-methoxypyrazine (IBMP) and β-damascenone]. A comparison of SPMESH-DART-MS and SPME-GC-MS quantitation of linalool and IBMP demonstrates excellent agreement between the two methods for real grape samples (r 2 ≥ 0.90), although linalool measurements appeared to also include isobaric interference.

Dissociable Electroencephalograph Correlates of Visual Awareness and Feature-Based Attention

PubMed Central

Chen, Yifan; Wang, Xiaochun; Yu, Yanglan; Liu, Ying

2017-01-01

Background: The relationship between awareness and attention is complex and controversial. A growing body of literature has shown that the neural bases of consciousness and endogenous attention (voluntary attention) are independent. The important role of exogenous attention (reflexive attention) on conscious experience has been noted in several studies. However, exogenous attention can also modulate subliminal processing, suggesting independence between the two processes. The question of whether visual awareness and exogenous attention rely on independent mechanisms under certain circumstances remains unanswered. Methods: In the current study, electroencephalograph recordings were conducted using 64 channels from 16 subjects while subjects attempted to detect faint speed changes of colored rotating dots. Awareness and attention were manipulated throughout trials in order to test whether exogenous attention and visual awareness rely on independent mechanisms. Results: Neural activity related to consciousness was recorded in the following cue-locked time-windows (event related potential, cluster- based permutation test): 0–50, 150–200, and 750–800 ms. With a more liberal threshold, the inferior occipital lobe was found to be the source of awareness-related activity in the 0–50 ms range. In the later 150–200 ms range, activity in the fusiform and post-central gyrus was related to awareness. Awareness-related activation in the later 750–800 ms range was more widely distributed. This awareness-related activation pattern was quite different from that of attention. Attention-related neural activity was emphasized in the 750–800 ms time window and the main source of attention-related activity was localized to the right angular gyrus. These results suggest that exogenous attention and visual consciousness correspond to different and relatively independent neural mechanisms and are distinct processes under certain conditions. PMID:29180950

Colliding-Droplet Microreactor: Rapid On-Demand Inertial Mixing and Metal-Catalyzed Aqueous Phase Oxidation Processes.

PubMed

Davis, Ryan D; Jacobs, Michael I; Houle, Frances A; Wilson, Kevin R

2017-11-21

In-depth investigations of the kinetics of aqueous chemistry occurring in microdroplet environments require experimental techniques that allow a reaction to be initiated at a well-defined point in time and space. Merging microdroplets of different reactants is one such approach. The mixing dynamics of unconfined (airborne) microdroplets have yet to be studied in detail, which is an essential step toward widespread use and application of merged droplet microreactors for monitoring chemical reactions. Here, we present an on-demand experimental approach for initiating chemical reactions in and characterizing the mixing dynamics of colliding airborne microdroplets (40 ± 5 μm diameter) using a streak-based fluorescence microscopy technique. The advantages of this approach include the ability to generate two well-controlled monodisperse microdroplet streams and collide (and thus mix) the microdroplets with high spatial and temporal control while consuming small amounts of sample (<0.1 μL/s). Mixing times are influenced not only by the velocity at which microdroplets collide but also the geometry of the collision (i.e., head-on vs off-center collision). For head-on collisions, we achieve submillisecond mixing times ranging from ∼900 μs at a collision velocity of 0.1 m/s to <200 μs at ∼6 m/s. For low-velocity (<1 m/s) off-center collisions, mixing times were consistent with the head-on cases. For high-velocity (i.e., > 1 m/s) off-center collisions, mixing times increased by as much as a factor of 6 (e.g., at ∼6 m/s, mixing times increased from <200 μs for head-on collisions to ∼1200 μs for highly off-center collisions). At collision velocities >7 m/s, droplet separation and fragmentation occurred, resulting in incomplete mixing. These results suggest a limited range of collision velocities over which complete and rapid mixing can be achieved when using airborne merged microdroplets to, e.g., study reaction kinetics when reaction times are short relative to typical bulk reactor mixing times. We benchmark our reactor using an aqueous-phase oxidation reaction: iron-catalyzed hydroxyl radical production from hydrogen peroxide (Fenton's reaction) and subsequent aqueous-phase oxidation of organic species in solution. Kinetic simulations of our measurements show that quantitative agreement can be obtained using known bulk-phase kinetics for bimolecular reactions in our colliding-droplet microreactor.

Colliding-Droplet Microreactor: Rapid On-Demand Inertial Mixing and Metal-Catalyzed Aqueous Phase Oxidation Processes

DOE PAGES

Davis, Ryan D.; Jacobs, Michael I.; Houle, Frances A.; ...

2017-10-30

In-depth investigations of the kinetics of aqueous chemistry occurring in microdroplet environments require experimental techniques that allow a reaction to be initiated at a well-defined point in time and space. Merging microdroplets of different reactants is one such approach. The mixing dynamics of unconfined (airborne) microdroplets have yet to be studied in detail, which is an essential step toward widespread use and application of merged droplet microreactors for monitoring chemical reactions. Here, we present an on-demand experimental approach for initiating chemical reactions in and characterizing the mixing dynamics of colliding airborne microdroplets (40 ± 5 μm diameter) using a streak-basedmore » fluorescence microscopy technique. The advantages of this approach include the ability to generate two well-controlled monodisperse microdroplet streams and collide (and thus mix) the microdroplets with high spatial and temporal control while consuming small amounts of sample (<0.1 μL/s). Mixing times are influenced not only by the velocity at which microdroplets collide but also the geometry of the collision (i.e., head-on vs off-center collision). For head-on collisions, we achieve submillisecond mixing times ranging from ~900 μs at a collision velocity of 0.1 m/s to <200 μs at ~6 m/s. For low-velocity (<1 m/s) off-center collisions, mixing times were consistent with the head-on cases. For high-velocity (i.e., > 1 m/s) off-center collisions, mixing times increased by as much as a factor of 6 (e.g., at ~6 m/s, mixing times increased from <200 μs for head-on collisions to ~1200 μs for highly off-center collisions). At collision velocities >7 m/s, droplet separation and fragmentation occurred, resulting in incomplete mixing. These results suggest a limited range of collision velocities over which complete and rapid mixing can be achieved when using airborne merged microdroplets to, e.g., study reaction kinetics when reaction times are short relative to typical bulk reactor mixing times. We benchmark our reactor using an aqueous-phase oxidation reaction: iron-catalyzed hydroxyl radical production from hydrogen peroxide (Fenton's reaction) and subsequent aqueous-phase oxidation of organic species in solution. In conclusion, kinetic simulations of our measurements show that quantitative agreement can be obtained using known bulk-phase kinetics for bimolecular reactions in our colliding-droplet microreactor.« less

Colliding-Droplet Microreactor: Rapid On-Demand Inertial Mixing and Metal-Catalyzed Aqueous Phase Oxidation Processes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Davis, Ryan D.; Jacobs, Michael I.; Houle, Frances A.

In-depth investigations of the kinetics of aqueous chemistry occurring in microdroplet environments require experimental techniques that allow a reaction to be initiated at a well-defined point in time and space. Merging microdroplets of different reactants is one such approach. The mixing dynamics of unconfined (airborne) microdroplets have yet to be studied in detail, which is an essential step toward widespread use and application of merged droplet microreactors for monitoring chemical reactions. Here, we present an on-demand experimental approach for initiating chemical reactions in and characterizing the mixing dynamics of colliding airborne microdroplets (40 ± 5 μm diameter) using a streak-basedmore » fluorescence microscopy technique. The advantages of this approach include the ability to generate two well-controlled monodisperse microdroplet streams and collide (and thus mix) the microdroplets with high spatial and temporal control while consuming small amounts of sample (<0.1 μL/s). Mixing times are influenced not only by the velocity at which microdroplets collide but also the geometry of the collision (i.e., head-on vs off-center collision). For head-on collisions, we achieve submillisecond mixing times ranging from ~900 μs at a collision velocity of 0.1 m/s to <200 μs at ~6 m/s. For low-velocity (<1 m/s) off-center collisions, mixing times were consistent with the head-on cases. For high-velocity (i.e., > 1 m/s) off-center collisions, mixing times increased by as much as a factor of 6 (e.g., at ~6 m/s, mixing times increased from <200 μs for head-on collisions to ~1200 μs for highly off-center collisions). At collision velocities >7 m/s, droplet separation and fragmentation occurred, resulting in incomplete mixing. These results suggest a limited range of collision velocities over which complete and rapid mixing can be achieved when using airborne merged microdroplets to, e.g., study reaction kinetics when reaction times are short relative to typical bulk reactor mixing times. We benchmark our reactor using an aqueous-phase oxidation reaction: iron-catalyzed hydroxyl radical production from hydrogen peroxide (Fenton's reaction) and subsequent aqueous-phase oxidation of organic species in solution. In conclusion, kinetic simulations of our measurements show that quantitative agreement can be obtained using known bulk-phase kinetics for bimolecular reactions in our colliding-droplet microreactor.« less

Effects of variable regolith depth, hydraulic properties, and rainfall on debris-flow initiation during the September 2013 northern Colorado Front Range rainstorm

NASA Astrophysics Data System (ADS)

Baum, R. L.; Coe, J. A.; Kean, J. W.; Jones, E. S.; Godt, J.

2015-12-01

Heavy rainfall during 9 - 13 September 2013 induced about 1100 debris flows in the foothills and mountains of the northern Colorado Front Range. Weathered bedrock was partially exposed in the basal surfaces of many of the shallow source areas at depths ranging from 0.2 to 5 m. Typical values of saturated hydraulic conductivity of soils and regolith units mapped in the source areas range from about 10-4 - 10-6 m/s, with a median value of 2.8 x 10-5 m/s based on number of source areas in each map unit. Rainfall intensities varied spatially and temporally, from 0 to 2.5 x 10-5 m/s (90 mm/hour), with two periods of relatively heavy rainfall on September 12 - 13. The distribution of debris flows appears to correlate with total storm rainfall, and reported times of greatest landslide activity coincide with times of heaviest rainfall. Process-based models of rainfall infiltration and slope stability (TRIGRS) representing the observed ranges of regolith depth, hydraulic conductivity, and rainfall intensity, provide additional insights about the timing and distribution of debris flows from this storm. For example, small debris flows from shallower source areas (<2 m) occurred late on September 11 and in the early morning of September 12, whereas large debris flows from deeper (3 - 5 m) source areas in the western part of the affected area occurred late on September 12. Timing of these flows can be understood in terms of the time required for pore pressure rise depending on regolith depth and rainfall intensity. The variable hydraulic properties combined with variable regolith depth and slope angles account for much of the observed range in timing in areas of similar rainfall intensity and duration. Modeling indicates that the greatest and most rapid pore pressure rise likely occurred in areas of highest rainfall intensity and amount. This is consistent with the largest numbers of debris flows occurring on steep canyon walls in areas of high total storm rainfall.

On-line solid phase extraction using the Prospekt-2 coupled with a liquid chromatography/tandem mass spectrometer for the determination of dextromethorphan, dextrorphan and guaifenesin in human plasma.

PubMed

Kuhlenbeck, Debbie L; Eichold, Thomas H; Hoke, Steven H; Baker, Timothy R; Mensen, Robert; Wehmeyer, Kenneth R

2005-01-01

An on-line liquid chromatography/tandem mass spectrometry (LC-MS/MS) procedure, using the Prospekt- 2 system, was developed and used for the determination of the levels of the active ingredients of cough/cold medications in human plasma matrix. The experimental configuration allows direct plasma injection by performing on- line solid phase extraction (SPE) on small cartridge columns prior to elution of the analyte(s) onto the analytical column and subsequent MS/MS detection. The quantitative analysis of three analytes with differing polarities, dextromethorphan (DEX), dextrorphan (DET) and guaifenesin (GG) in human plasma presented a significant challenge. Using stable-isotope-labeled internal standards for each analyte, the Prospekt-2 on-line methodology was evaluated for sensitivity, suppression, accuracy, precision, linearity, analyst time, analysis time, cost, carryover and ease of use. The lower limit of quantitation for the on-line SPE procedure for DEX, DET and GG was 0.05, 0.05 and 5.0 ng mL(-1), respectively, using a 0.1 mL sample volume. The linear range for DEX and DET was 0.05-50 ng mL(-1) and was 5-5,000 ng mL(-1) for GG. Accuracy and precision data for five different levels of QC samples were collected over three separate days. Accuracy ranged from 90% to 112% for all three analytes, while the precision, as measured by the %RSD, ranged from 1.5% to 16.0%

Postural response latencies are related to balance control during standing and walking in patients with multiple sclerosis

PubMed Central

Huisinga, Jessie M.; St. George, Rebecca J.; Spain, Rebecca; Overs, Shannon; Horak, Fay B.

2015-01-01

Objective To understand examined the relationship between postural response latencies obtained during postural perturbations and representative measures of balance during standing (sway variables) and during walking (trunk motion). Design Cross-sectional Setting University medical center balance disorders laboratory Participants Forty persons with MS were compared with 20 similar aged control subjects. Twenty subjects with MS had normal walking velocity group and 20 had slow walking velocity based on the 25-foot walk time greater than 5 seconds. Interventions None Main Outcome Measures Postural response latency, sway variables, trunk motion variables Results: We found that subjects with MS with either slow or normal walking velocities had significantly longer postural response latencies than the healthy control group. Postural response latency was not correlated with the 25-ft walk time. Postural response latency was significantly correlated with center of pressure sway variables during quiet standing: root mean square (ρ = 0.334, p=0.040), range (ρ=0.385, p=0.017), mean velocity (ρ=0.337, p=0.038), and total sway area (ρ=0.393, p=0.015). Postural response latency was also significantly correlated with motion of the trunk during walking: sagittal plane range of motion (ρ=0.316, p=0.050) and standard deviation of transverse plane range of motion (ρ=-0.430, p=0.006). Conclusions These findings clearly indicate that slow postural responses to external perturbations in patients with MS contribute to disturbances in balance control, both during standing and walking. PMID:24445088

Study of vortex-assisted MSPD and LC-MS/MS using alternative solid supports for pharmaceutical extraction from marketed fish.

PubMed

Hertzog, Gabriel I; Soares, Karina L; Caldas, Sergiane S; Primel, Ednei G

2015-06-01

A procedure based on vortex-assisted matrix solid-phase dispersion (MSPD) for the extraction of 15 pharmaceuticals from fish samples with determination by liquid chromatography-tandem mass spectrometry (LC-MS/MS) was validated. Florisil, C18, diatomaceous earth, chitin, and chitosan were evaluated as solid supports. Best results were obtained with 0.5 g of diatomaceous earth, 0.5 g of sodium sulfate, and 5 mL of methanol. Analytical recoveries ranged from 58 to 128 % with relative standard deviation (RSD) lower than 15 %. Limit of quantification (LOQ) values for the 15 compounds ranged from 5 to 1000 ng g(-1). The method under investigation has shown to be a simple and fast extraction tool with minimum instrumentation and low amount of reagent, resulting in method low cost. Besides, alternative materials, such as chitin and chitosan, which were applied to the dispersion step for the first time, were found to be interesting alternatives.

In-Plane Ultrasound Propagation in an Elastic Silicone Tube as a Function of Tension

NASA Astrophysics Data System (ADS)

Rajakenttä, Tina; Salmi, Ari; Akujärvi, Altti; Haapalainen, Jonne; Hæggström, Edward

2007-03-01

The mechanical properties of a silicone tube blood vessel phantom (outer radius 4.04±0.04 mm and wall thickness 1.00±0.02 mm) carrying in-plane ultrasound wave propagation, was studied as function of applied axial tension. A 23 kHz, 1-cycle square signal was excited into the tube with a piezoceramic pickup and received with an inductive pickup. The wave phase velocities in the tube were determined by measuring the time-of-flight (TOF) at different inter-transducer distances. The longitudinal mode sound velocity ranged from 83 m/s to 88 m/s, and from 51 m/s to 58 m/s for the shear mode respectively with tensions ranging from 31 to 364 kPa. This compares with the FEM estimate. A laser-Doppler vibrometer (LDV) detected an out-of-plane mode propagating along the tube. An increase in the sound velocity caused by artificially induced lesions was detected.

Online health information seeking: how people with multiple sclerosis find, assess and integrate treatment information to manage their health.

PubMed

Synnot, Anneliese J; Hill, Sophie J; Garner, Kerryn A; Summers, Michael P; Filippini, Graziella; Osborne, Richard H; Shapland, Sue D P; Colombo, Cinzia; Mosconi, Paola

2016-06-01

The Internet is increasingly prominent as a source of health information for people with multiple sclerosis (MS). But there has been little exploration of the needs, experiences and preferences of people with MS for integrating treatment information into decision making, in the context of searching on the Internet. This was the aim of our study. Sixty participants (51 people with MS; nine family members) took part in a focus group or online forum. They were asked to describe how they find and assess reliable treatment information (particularly online) and how this changes over time. Thematic analysis was underpinned by a coding frame. Participants described that there was both too much information online and too little that applied to them. They spoke of wariness and scepticism but also empowerment. The availability of up-to-date and unbiased treatment information, including practical and lifestyle-related information, was important to many. Many participants were keen to engage in a 'research partnership' with health professionals and developed a range of strategies to enhance the trustworthiness of online information. We use the term 'self-regulation' to capture the variations in information seeking behaviour that participants described over time, as they responded to their changing information needs, their emotional state and growing expertise about MS. People with MS have developed a number of strategies to both find and integrate treatment information from a range of sources. Their reflections informed the development of an evidence-based consumer web site based on summaries of MS Cochrane reviews. © 2014 John Wiley & Sons Ltd.

Bioassay of safinamide in biological fluids of humans and various animal species.

PubMed

Dal Bo, Lorenzo; Mazzucchelli, Paolo; Fibbioli, Monia; Marzo, Antonio

2006-01-01

This paper describes three methods to bioassay safinamide (CAS 133865-89-1) in biological fluids of humans and laboratory animals for pharmacokinetic, toxicokinetic and bioavailability studies. Two methods profited from liquid chromatography tandem mass spectrometry (LC-MS-MS) system, one (micro bioassay) working in the low dynamic range 0.5-20 ng/ml, the other in the range 20-6000 ng/ml. A third method used high-performance liquid chromatrography with fluorimetric detection (HPLC-FD), working in the dynamic range 20-1000 ng/ml. All the three methods were validated in compliance with the accreditated views on analytical bioassays. The shorter run time (5.5 min vs 16 min) has led the authors to prefer the two LC-MS-MS methods to the HPLC-FD bioassay, even if all the performances of the three methods were excellent. The methods described in this paper were and are still now extensively used to assay safinamide in more than 10,000 specimens of biological fluids from humans and laboratory animals in the development program of the drug. Main pharmacokinetic results obtained in various Phase I trials on healthy volunteers are briefly reported.

SU-D-18C-05: Variable Bolus Arterial Spin Labeling MRI for Accurate Cerebral Blood Flow and Arterial Transit Time Mapping

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnston, M; Jung, Y

2014-06-01

Purpose: Arterial spin labeling (ASL) is an MRI perfusion imaging method from which quantitative cerebral blood flow (CBF) maps can be calculated. Acquisition with variable post-labeling delays (PLD) and variable TRs allows for arterial transit time (ATT) mapping and leads to more accurate CBF quantification with a scan time saving of 48%. In addition, T1 and M0 maps can be obtained without a separate scan. In order to accurately estimate ATT and T1 of brain tissue from the ASL data, variable labeling durations were invented, entitled variable-bolus ASL. Methods: All images were collected on a healthy subject with a 3Tmore » Siemens Skyra scanner. Variable-bolus Psuedo-continuous ASL (PCASL) images were collected with 7 TI times ranging 100-4300ms in increments of 700ms with TR ranging 1000-5200ms. All boluses were 1600ms when the TI allowed, otherwise the bolus duration was 100ms shorter than the TI. All TI times were interleaved to reduce sensitivity to motion. Voxel-wise T1 and M0 maps were estimated using a linear least squares fitting routine from the average singal from each TI time. Then pairwise subtraction of each label/control pair and averaging for each TI time was performed. CBF and ATT maps were created using the standard model by Buxton et al. with a nonlinear fitting routine using the T1 tissue map. Results: CBF maps insensitive to ATT were produced along with ATT maps. Both maps show patterns and averages consistent with literature. The T1 map also shows typical T1 contrast. Conclusion: It has been demonstrated that variablebolus ASL produces CBF maps free from the errors due to ATT and tissue T1 variations and provides M0, T1, and ATT maps which have potential utility. This is accomplished with a single scan in a feasible scan time (under 6 minutes) with low sensivity to motion.« less

Microfluidic LC Device with Orthogonal Sample Extraction for On-Chip MALDI-MS Detection

PubMed Central

Lazar, Iulia M.; Kabulski, Jarod L.

2013-01-01

A microfluidic device that enables on-chip matrix assisted laser desorption ionization-mass spectrometry (MALDI-MS) detection for liquid chromatography (LC) separations is described. The device comprises an array of functional elements to carry out LC separations, integrates a novel microchip-MS interface to facilitate the orthogonal transposition of the microfluidic LC channel into an array of reservoirs, and enables sensitive MALDI-MS detection directly from the chip. Essentially, the device provides a snapshot MALDI-MS map of the content of the separation channel present on the chip. The detection of proteins with biomarker potential from MCF10A breast epithelial cell extracts, and detection limits in the low fmol range, are demonstrated. In addition, the design of the novel LC-MALDI-MS chip entices the promotion of a new concept for performing sample separations within the limited time-frame that accompanies the dead-volume of a separation channel. PMID:23592150

MS Based Metabonomics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Want, Elizabeth J.; Metz, Thomas O.

Metabonomics is the latest and least mature of the systems biology triad, which also includes genomics and proteomics, and has its origins in the early orthomolecular medicine work pioneered by Linus Pauling and Arthur Robinson. It was defined by Nicholson and colleagues in 1999 as the quantitative measurement of perturbations in the metabolite complement of an integrated biological system in response to internal or external stimuli, and is often used today to describe many non-global types of metabolite analyses. Applications of metabonomics are extensive and include toxicology, nutrition, pharmaceutical research and development, physiological monitoring and disease diagnosis. For example, bloodmore » samples from millions of neonates are tested routinely by mass spectrometry (MS) as a diagnostic tool for inborn errors of metabolism. The metabonome encompasses a wide range of structurally diverse metabolites; therefore, no single analytical platform will be sufficient. Specialized sample preparation and detection techniques are required, and advances in NMR and MS technologies have led to enhanced metabonome coverage, which in turn demands improved data analysis approaches. The role of MS in metabonomics is still evolving as instrumentation and software becomes more sophisticated and as researchers realize the strengths and limitations of current technology. MS offers a wide dynamic range, high sensitivity, and reproducible, quantitative analysis. These attributes are essential for addressing the challenges of metabonomics, as the range of metabolite concentrations easily exceeds nine orders of magnitude in biofluids, and the diversity of molecular species ranges from simple amino and organic acids to lipids and complex carbohydrates. Additional challenges arise in generating a comprehensive metabolite profile, downstream data processing and analysis, and structural characterization of important metabolites. A typical workflow of MS-based metabonomics is shown in Figure 1. Gas chromatography-(GC)-MS was the most commonly used MS-based method for small molecule analysis in the 1970s and 1980s. It is still used today for the detection of many metabolic disorders and plays a strong role in plant metabonomics. Liquid chromatography (LC)-MS approaches have grown in popularity for metabolite studies, due to simpler sample preparation, reduced analysis times through the introduction of ultra-high performance liquid chromatography (UPLC)-MS and the ability to observe a wider range of metabolites. This chapter will discuss the role of MS in metabonomics, the techniques involved in this exciting area, and the current and future applications of the field. The various bioinformatics tools and multivariate analysis techniques used to maximize information recovery and to aid in the interpretation of the very large data sets typically obtained in metabonomics studies will also be discussed. While there are many different MS-based approaches utilized in metabonomics studies, emphasis will be placed on more established methods.« less

Direct Analysis and Quantification of Metaldehyde in Water using Reactive Paper Spray Mass Spectrometry

PubMed Central

Maher, Simon; Jjunju, Fred P. M.; Damon, Deidre E.; Gorton, Hannah; Maher, Yosef S.; Syed, Safaraz U.; Heeren, Ron M. A.; Young, Iain S.; Taylor, Stephen; Badu-Tawiah, Abraham K.

2016-01-01

Metaldehyde is extensively used worldwide as a contact and systemic molluscicide for controlling slugs and snails in a wide range of agricultural and horticultural crops. Contamination of surface waters due to run-off, coupled with its moderate solubility in water, has led to increased concentration of the pesticide in the environment. In this study, for the first time, rapid analysis (<~1 minute) of metaldehyde residues in water is demonstrated using paper spray mass spectrometry (PS-MS). The observed precursor molecular ions of metaldehyde were confirmed from tandem mass spectrometry (MS/MS) experiments by studying the fragmentation patterns produced via collision-induced dissociation. The signal intensity ratios of the most abundant MS/MS transitions for metaldehyde (177 → 149 for protonated ion) and atrazine (221 → 179) were found to be linear in the range 0.01 to 5 ng/mL. Metaldehyde residues were detectable in environmental water samples at low concentration (LOD < 0.1 ng/mL using reactive PS-MS), with a relative standard deviation <10% and an R2 value >0.99, without any pre-concentration/separation steps. This result is of particular importance for environmental monitoring and water quality analysis providing a potential means of rapid screening to ensure safe drinking water. PMID:27767044

Black phosphorus-assisted laser desorption ionization mass spectrometry for the determination of low-molecular-weight compounds in biofluids.

PubMed

He, Xiao-Mei; Ding, Jun; Yu, Lei; Hussain, Dilshad; Feng, Yu-Qi

2016-09-01

Quantitative analysis of small molecules by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been a challenging task due to matrix-derived interferences in low m/z region and poor reproducibility of MS signal response. In this study, we developed an approach by applying black phosphorus (BP) as a matrix-assisted laser desorption ionization (MALDI) matrix for the quantitative analysis of small molecules for the first time. Black phosphorus-assisted laser desorption/ionization mass spectrometry (BP/ALDI-MS) showed clear background and exhibited superior detection sensitivity toward quaternary ammonium compounds compared to carbon-based materials. By combining stable isotope labeling (SIL) strategy with BP/ALDI-MS (SIL-BP/ALDI-MS), a variety of analytes labeled with quaternary ammonium group were sensitively detected. Moreover, the isotope-labeled forms of analytes also served as internal standards, which broadened the analyte coverage of BP/ALDI-MS and improved the reproducibility of MS signals. Based on these advantages, a reliable method for quantitative analysis of aldehydes from complex biological samples (saliva, urine, and serum) was successfully established. Good linearities were obtained for five aldehydes in the range of 0.1-20.0 μM with correlation coefficients (R (2)) larger than 0.9928. The LODs were found to be 20 to 100 nM. Reproducibility of the method was obtained with intra-day and inter-day relative standard deviations (RSDs) less than 10.4 %, and the recoveries in saliva samples ranged from 91.4 to 117.1 %. Taken together, the proposed SIL-BP/ALDI-MS strategy has proved to be a reliable tool for quantitative analysis of aldehydes from complex samples. Graphical Abstract An approach for the determination of small molecules was developed by using black phosphorus (BP) as a matrix-assisted laser desorption ionization (MALDI) matrix.

HPLC-DAD and HPLC-ESI-MS/MS methods for metabolite profiling of propolis extracts.

PubMed

Pellati, Federica; Orlandini, Giulia; Pinetti, Diego; Benvenuti, Stefania

2011-07-15

In this study, the composition of polyphenols (phenolic acids and flavonoids) in propolis extracts was investigated by HPLC-DAD and HPLC-ESI-MS/MS by comparing the performance of ion trap and triple quadrupole mass analyzers. The analyses were carried out on an Ascentis C(18) column (250mm×4.6mm I.D., 5μm), with a mobile phase composed by 0.1% formic acid in water and acetonitrile. Overall, the UV spectra, the MS and MS/MS data allowed the identification of 40 compounds. In the case of flavonoids, the triple quadrupole mass analyzer provided more collision energy if compared with the ion trap, originating product ions at best sensitivity. The HPLC method was validated in agreement with ICH guidelines: the correlation coefficients were >0.998; the limit of detection was in the range 1.6-4.6μg/ml; the recovery range was 96-105%; the intra- and inter-day %RSD values for retention times and peak areas were found to be <0.3 and 1.9%, respectively. The developed technique was applied to the analysis of hydroalcoholic extracts of propolis available on the Italian market. Although the chromatographic profile of the analyzed samples was similar, the quantitative analysis indicated that there is a great variability in the amount of the active compounds: the content of total phenolic acids ranged from 0.17 to 16.67mg/ml and the level of total flavonoids from 2.48 to 41.10mg/ml. The proposed method can be considered suitable for the phytochemical analysis of propolis extracts used in phytotherapy. Copyright © 2011 Elsevier B.V. All rights reserved.

Milrinone therapeutic drug monitoring in a pediatric population: Development and validation of a quantitative liquid chromatography-tandem mass spectrometry method.

PubMed

Raizman, Joshua E; Taylor, Katherine; Parshuram, Christopher; Colantonio, David A

2017-05-01

Milrinone is a potent selective phosphodiesterase type III inhibitor which stimulates myocardial function and improves myocardial relaxation. Although therapeutic monitoring is crucial to maintain therapeutic outcome, little data is available. A proof-of-principle study has been initiated in our institution to evaluate the clinical impact of optimizing milrinone dosing through therapeutic drug monitoring (TDM) in children following cardiac surgery. We developed a robust LC-MS/MS method to quantify milrinone in serum from pediatric patients in real-time. A liquid-liquid extraction procedure was used to prepare samples for analysis prior to measurement by LC-MS/MS. Performance characteristics, such as linearity, limit of quantitation (LOQ) and precision, were assessed. Patient samples were acquired post-surgery and analyzed to determine the concentration-time profile of the drug as well as to track turn-around-times. Within day precision was <8.3% across 3 levels of QC. Between-day precision was <12%. The method was linear from 50 to 800μg/l; the lower limit of quantification was 22μg/l. Comparison with another LC-MS/MS method showed good agreement. Using this simplified method, turnaround times within 3-6h were achievable, and patient drug profiles demonstrated that some milrinone levels were either sub-therapeutic or in the toxic range, highlighting the importance for milrinone TDM. This simplified and quick method proved to be analytically robust and able to provide therapeutic monitoring of milrinone in real-time in patients post-cardiac surgery. Copyright © 2017. Published by Elsevier B.V.

Rapid Analysis of Bisphenol A and Its Analogues in Food Packaging Products by Paper Spray Ionization Mass Spectrometry.

PubMed

Chen, Shuo; Chang, Quanying; Yin, Kai; He, Qunying; Deng, Yongxiu; Chen, Bo; Liu, Chengbin; Wang, Ying; Wang, Liping

2017-06-14

In this study, a paper spray ionization mass spectrometric (PS-MS) method was developed for the rapid in situ screening and simultaneous quantitative analysis of bisphenol A and its analogues, i.e., bisphenol S, bisphenol F, and bisphenol AF, in food packaging products. At the optimal PS-MS conditions, the calibration curves of bisphenols in the range of 1-100 μg/mL were linear. The correlation coefficients were higher than 0.998, and the LODs of the target compounds were 0.1-0.3 μg/mL. After a simple treatment by dichloromethane on the surface, the samples were analyzed by PS-MS in situ for rapid screening without a traditional sample pretreatment procedure, such as powdering, extraction, and enrichment steps. The analytical time of the PS-MS method was less than 1 min. In comparison with conventional HPLC-MS/MS, it was demonstrated that PS-MS was a more effective high-throughput screening and quantitative analysis method.

Evaluation and Refinement of Euthanasia Methods for Xenopus laevis

PubMed Central

Torreilles, Stéphanie L; McClure, Diane E; Green, Sherril L

2009-01-01

The most common method of euthanasia for Xenopus species is by immersion in tricaine methane sulfonate solution (MS222). A wide range of doses of MS222 (0.5 to 5 g/L) have been recommended, but few reports describe dose–response testing, the time to loss of consciousness, or the reliability of euthanasia. The objective of this study is to evaluate the efficacy of immersing individual and groups of frogs in MS222 at concentrations ranging from 1 to 5 g/L for euthanasia and of 3 less-common methods: intracoelomic injection of MS222, intracoelomic injection of sodium pentobarbital with phenytoin, and ventral cutaneous application of benzocaine gel. Our results indicate that immersion for at least 1 h in a 5-g/L buffered solution of MS222, intracoelomic injection of 1100 mg/kg sodium pentobarbital with sodium phenytoin (equivalent to 0.3 mL solution per frog), or ventral cutaneous application of 182 mg/kg benzocaine (equivalent to a 2 cm × 1 mm of 20% benzocaine gel) is necessary to euthanize adult X. laevis and ensure complete cessation of the heartbeat without recovery. These doses are considerably higher than those previously recommended for this species. PMID:19807972

Determination of the aflatoxin AFB1 from corn by direct analysis in real time-mass spectrometry (DART-MS).

PubMed

Busman, Mark; Liu, Jihong; Zhong, Hongjian; Bobell, John R; Maragos, Chris M

2014-01-01

Direct analysis in real time (DART) ionisation coupled to a high-resolution mass spectrometer (MS) was used for screening of aflatoxins from a variety of surfaces and the rapid quantitative analysis of a common form of aflatoxin, AFB1, extracted from corn. Sample preparation procedure and instrument parameter settings were optimised to obtain sensitive and accurate determination of aflatoxin AFB1. 84:16 acetonitrile water extracts of corn were analysed by DART-MS. The lowest calibration level (LCL) for aflatoxin AFB1 was 4 μg kg⁻¹. Quantitative analysis was performed with the use of matrix-matched standards employing the ¹³C-labelled internal standard for AFB1. DART-MS of spiked corn extracts gave linear response in the range 4-1000 μg kg⁻¹. Good recoveries (94-110%) and repeatabilities (RSD = 0.7-6.9%) were obtained at spiking levels of 20 and 100 μg kg⁻¹ with the use of an isotope dilution technique. Trueness of data obtained for AFB1 in maize by DART-MS was demonstrated by analysis of corn certified reference materials.

About turn: how object orientation affects categorisation and mental rotation.

PubMed

Milivojevic, Branka; Hamm, Jeff P; Corballis, Michael C

2011-11-01

High-density ERPs evoked by rotated alphanumeric characters were examined to determine how neural processing is affected by stimulus orientation during letter/digit classifications and during mirror/normal discriminations. The former task typically produces response times that are unaffected by stimulus orientation while the latter is thought to require mental rotation. Sensitivity to orientation was first observed around 100-140 ms and this effect was attributed to differences in low-level features between vertical and oblique orientations. Subsequently, character misorientation amplified the N170, a neural marker of object classification, between 160 and 220 ms. Top-down processing is reflected in the ERPs beginning at 280-320 ms and this time range may reflect binding of ventral and dorsal stream information. In the case of mirror-normal discrimination these top-down processes can lead to mental rotation between 340 and 700 ms. Therefore, although neural processing reflects object orientation, these effects do not translate into increases in reaction-times or impaired accuracy for categorisation, and precede those that do in the mental-rotation task. Copyright © 2011 Elsevier Ltd. All rights reserved.

Open Probe fast GC-MS - combining ambient sampling ultra-fast separation and in-vacuum ionization for real-time analysis.

PubMed

Keshet, U; Alon, T; Fialkov, A B; Amirav, A

2017-07-01

An Open Probe inlet was combined with a low thermal mass ultra-fast gas chromatograph (GC), in-vacuum electron ionization ion source and a mass spectrometer (MS) of GC-MS for obtaining real-time analysis with separation. The Open Probe enables ambient sampling via sample vaporization in an oven that is open to room air, and the ultra-fast GC provides ~30-s separation, while if no separation is required, it can act as a transfer line with 2 to 3-s sample transfer time. Sample analysis is as simple as touching the sample, pushing the sample holder into the Open Probe oven and obtaining the results in 30 s. The Open Probe fast GC was mounted on a standard Agilent 7890 GC that was coupled with an Agilent 5977A MS. Open Probe fast GC-MS provides real-time analysis combined with GC separation and library identification, and it uses the low-cost MS of GC-MS. The operation of Open Probe fast GC-MS is demonstrated in the 30-s separation and 50-s full analysis cycle time of tetrahydrocannabinol and cannabinol in Cannabis flower, sub 1-min analysis of trace trinitrotoluene transferred from a finger onto a glass surface, vitamin E in canola oil, sterols in olive oil, polybrominated flame retardants in plastics, alprazolam in Xanax drug pill and free fatty acids and cholesterol in human blood. The extrapolated limit of detection for pyrene is <1 fg, but the concentration is too high and the software noise calculation is untrustworthy. The broad range of compounds amenable for analysis is demonstrated in the analysis of reserpine. The possible use with alternate standard GC-MS and Open Probe fast GC-MS is demonstrated in the analysis of heroin in its street drug powder. The use of Open Probe with the fast GC acting as a transfer line is demonstrated in <10-s analysis without separation of ibuprofen and estradiol. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

Velocity Model Analysis Based on Integrated Well and Seismic Data of East Java Basin

NASA Astrophysics Data System (ADS)

Mubin, Fathul; Widya, Aviandy; Eka Nurcahya, Budi; Nurul Mahmudah, Erma; Purwaman, Indro; Radityo, Aryo; Shirly, Agung; Nurwani, Citra

2018-03-01

Time to depth conversion is an important processof seismic interpretationtoidentify hydrocarbonprospectivity. Main objectives of this research are to minimize the risk of error in geometry and time to depth conversion. Since it’s using a large amount of data and had been doing in the large scale of research areas, this research can be classified as a regional scale research. The research was focused on three horizons time interpretation: Top Kujung I, Top Ngimbang and Basement which located in the offshore and onshore areas of east Java basin. These three horizons was selected because they were assumed to be equivalent to the rock formation, which is it has always been the main objective of oil and gas exploration in the East Java Basin. As additional value, there was no previous works on velocity modeling for regional scale using geological parameters in East Java basin. Lithology and interval thickness were identified as geological factors that effected the velocity distribution in East Java Basin. Therefore, a three layer geological model was generated, which was defined by the type of lithology; carbonate (layer 1: Top Kujung I), shale (layer 2: Top Ngimbang) and Basement. A statistical method using three horizons is able to predict the velocity distribution on sparse well data in a regional scale. The average velocity range for Top Kujung I is 400 m/s - 6000 m/s, Top Ngimbang is 500 m/s - 8200 m/s and Basement is 600 m/s - 8000 m/s. Some velocity anomalies found in Madura sub-basin area, caused by geological factor which identified as thick shale deposit and high density values on shale. Result of velocity and depth modeling analysis can be used to define the volume range deterministically and to make geological models to prospect generation in details by geological concept.

Simple and rapid LC-MS/MS method for the absolute determination of cetuximab in human serum using an immobilized trypsin.

PubMed

Shibata, Kaito; Naito, Takafumi; Okamura, Jun; Hosokawa, Seiji; Mineta, Hiroyuki; Kawakami, Junichi

2017-11-30

Proteomic approaches using liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) without an immunopurification technique have not been applied to the determination of serum cetuximab. This study developed a simple and rapid LC-MS/MS method for the absolute determination of cetuximab in human serum and applied it to clinical settings. Surrogate peptides derived from cetuximab digests were selected using a Fourier transform mass spectrometer. Reduced-alkylated serum cetuximab without immunopurification was digested for 20minutes using immobilized trypsin, and the digestion products were purified by solid-phase extraction. The LC-MS/MS was run in positive ion multiple reaction monitoring mode. This method was applied to the determination of serum samples in head and neck cancer patients treated with cetuximab. The chromatographic run time was 10minutes and no peaks interfering with surrogate peptides in serum digestion products were observed. The calibration curve of absolute cetuximab in serum was linear over the concentration range of 4-200μg/mL. The lower limit of quantification of cetuximab in human serum was 4μg/mL. The intra-assay and inter-assay precision and accuracy were less than 13.2% and 88.0-100.7%, respectively. The serum concentration range of cetuximab was 19-140μg/mL in patients. The serum cetuximab concentrations in LC-MS/MS were correlated with those in ELISA (r=0.899, P <0.01) and the mean bias was 1.5% in cancer patients. In conclusion, the present simple and rapid method with acceptable analytical performance can be helpful for evaluating the absolute concentration of serum cetuximab in clinical settings. Copyright © 2017 Elsevier B.V. All rights reserved.

Direct total and free testosterone measurement by liquid chromatography tandem mass spectrometry across two different platforms.

PubMed

Rhea, Jeanne M; French, Deborah; Molinaro, Ross J

2013-05-01

To develop and validate liquid chromatography tandem mass spectrometry (LC-MS/MS) methods for the direct measurement of total and free testosterone in patient samples on two different analytical systems. An API 4000 and 5000 triple quadropoles were used and compared; the former is reported to be 3-5 times less sensitive, as was used to set the quantitation limits. Free testosterone was separated from the protein-bound fraction by equilibrium dialysis followed by derivatization. Either free or total testosterone, and a deuterated internal standard (d3-testosterone) were extracted by liquid-liquid extraction. The validation results were compared to two different clinical laboratories. The use of d2-testosterone was found to be unacceptable for our method. The total testosterone LC-MS/MS methods on both systems were linear over a wide concentration range of 1.5-2000ng/dL. Free testosterone was measured directly using equilibrium dialysis coupled LC-MS/MS and linear over the concentration range of 2.5-2500pg/mL. Good correlation (total testosterone, R(2)=0.96; free testosterone, R(2)=0.98) was observed between our LC-MS/MS systems and comparator laboratory. However, differences in absolute values for both free and total testosterone measurements were observed while a comparison to a second published LC-MS/MS method showed excellent correlation. Free and total testosterone measurements correlated well with clinical observations. To our knowledge, this is the first published validation of free and total testosterone methods across two analytical systems of different analytical sensitivities. A less sensitive system does not sacrifice analytical or clinical sensitivity to directly measure free and total testosterone in patient samples. Copyright © 2013 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.

High precision mass measurements for wine metabolomics

PubMed Central

Roullier-Gall, Chloé; Witting, Michael; Gougeon, Régis D.; Schmitt-Kopplin, Philippe

2014-01-01

An overview of the critical steps for the non-targeted Ultra-High Performance Liquid Chromatography coupled with Quadrupole Time-of-Flight Mass Spectrometry (UPLC-Q-ToF-MS) analysis of wine chemistry is given, ranging from the study design, data preprocessing and statistical analyses, to markers identification. UPLC-Q-ToF-MS data was enhanced by the alignment of exact mass data from FTICR-MS, and marker peaks were identified using UPLC-Q-ToF-MS2. In combination with multivariate statistical tools and the annotation of peaks with metabolites from relevant databases, this analytical process provides a fine description of the chemical complexity of wines, as exemplified in the case of red (Pinot noir) and white (Chardonnay) wines from various geographic origins in Burgundy. PMID:25431760

Conversation Effects on Neural Mechanisms Underlying Reaction Time to Visual Events while Viewing a Driving Scene using MEG

PubMed Central

Bowyer, Susan M.; Hsieh, Li; Moran, John E.; Young, Richard A.; Manoharan, Arun; Liao, Chia-cheng Jason; Malladi, Kiran; Yu, Ya-Ju; Chiang, Yow-Ren; Tepley, Norman

2009-01-01

Magnetoencephalography (MEG) imaging examined the neural mechanisms that modulate reaction times to visual events while viewing a driving video, with and without a conversation. Twenty-four subjects ages 18–65 were monitored by whole-head MEG. The primary tasks were to monitor a driving video and to depress a foot pedal in response to a small red light presented to the left or below the driving scene at unpredictable times. The behavioral reaction time (RT) to the lights was recorded. The secondary task was a hands-free conversation. The subject pressed a button to answer a ring tone, and then covertly answered pre-recorded non-emotional questions such as “What is your birth date?” RTs for the conversation task (1043ms, SE=65ms) were slightly longer than for the primary task (baseline no conversation (944ms, SE=48ms). During the primary task RTs were inversely related to the amount of brain activity detected by MEG in the right superior parietal lobe (Brodmann’s Area 7). Brain activity was seen in the 200 to 300 ms range after the onset of the red light and in the visual cortex (BA 19) about 85 ms after the red light. Conversation reduced the strengths of these regression relationships and increased mean RT. Conversation may contribute to increased reaction times by (1) damping brain activation in specific regions during specific time windows, or (2) reducing facilitation from attention inputs into those areas. These laboratory findings should not be interpreted as indicative of real-world driving, without on-road validation, and comparison to other in-vehicle tasks. PMID:18992728

Determination of opiates and cocaine in urine by high pH mobile phase reversed phase UPLC-MS/MS.

PubMed

Berg, Thomas; Lundanes, Elsa; Christophersen, Asbjørg S; Strand, Dag Helge

2009-02-01

A fast and selective ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for the determination of opiates (morphine, codeine, 6-monoacetylmorphine (6-MAM), pholcodine, oxycodone, ethylmorphine), cocaine and benzoylecgonine in urine has been developed and validated. Sample preparation was performed by solid phase extraction (SPE) on a mixed mode cation exchange (MCX) cartridge. For optimized chromatographic performance with repeatable retention times, narrow and symmetrical peaks, and focusing of all analytes at the column inlet at gradient start, a basic mobile phase consisting of 5mM ammonium bicarbonate, pH 10.2, and methanol (MeOH) was chosen. Positive electrospray ionization (ESI(+)) MS/MS detection was performed with a minimum of two multiple reaction monitoring (MRM) transitions for each analyte. Deuterium labelled-internal standards were used for six of the analytes. Between-assay retention time repeatabilities (n=10 series, 225 injections in total) had relative standard deviation (RSD) values within 0.1-0.6%. Limit of detection (LOD) and limit of quantification (LOQ) values were in the range 0.003-0.05 microM (0.001-0.02 microg/mL) and 0.01-0.16 microM (0.003-0.06 microg/mL), respectively. The RSD values of the between-assay repeatabilities of concentrations were

To what extent the repeating earthquakes repeated? - Analyses of 1982 and 2008 Ibaraki-ken-oki M7 class earthquakes using strong motion records -

NASA Astrophysics Data System (ADS)

Takiguchi, M.; Asano, K.; Iwata, T.

2010-12-01

Two M7 class subduction zone earthquakes have occurred in the Ibaraki-ken-oki region, northeast Japan, at 23:23 on July 23, 1982 JST (Mw7.0; 1982MS) and at 01:45 on May 8, 2008 JST (Mw6.8; 2008MS). It has been reported that, from the results of the teleseismic waveform inversion, the rupture of the asperity repeated (HERP, 2010). We estimated the source processes of these earthquakes in detail by analyzing the strong motion records and discussed how much the source characteristics of the two earthquakes repeated. First, we estimated the source model of 2008MS following the method of Miyake et al. (2003). The best-fit set of the model parameters was determined by a grid search using forward modeling of broad-band ground motions. A single 12.6 km × 12.6 km rectangular Strong Motion Generation Area (SMGA, Miyake et al., 2003) was estimated. The rupture of the SMGA of 2008MS (2008SMGA) started from the hypocenter and propagated mainly to northeast. Next, we estimated the source model of 1982MS. We compared the waveforms of 1982MS and 2008MS recorded at the same stations and found the initial rupture phase before the main rupture phase on the waveforms of 1982MS. The travel time analysis showed that the main rupture of the 1982MS started approximately 33 km west of the hypocenter at about 11s after the origin time. The main rupture starting point was located inside 2008SMGA, suggesting that the two SMGAs overlapped in part. The seismic moment ratio of 1982MS to 2008MS was approximately 1.6, and we also found the observed acceleration amplitude spectra of 1982MS were 1.5 times higher than those of 2008MS in the available frequency range. We performed the waveform modeling for 1982MS with a constraint of these ratios. A single rectangular SMGA (1982SMGA) was estimated for the main rupture, which had the same size and the same rupture propagation direction as those of 2008SMGA. However, the estimated stress drop or average slip amount of 1982SMGA was 1.5 times larger than those of 2008SMGA.

Site-specific N-glycosylation analysis: matrix-assisted laser desorption/ionization quadrupole-quadrupole time-of-flight tandem mass spectral signatures for recognition and identification of glycopeptides.

PubMed

Krokhin, Oleg; Ens, Werner; Standing, Kenneth G; Wilkins, John; Perreault, Hélène

2004-01-01

The identification of glycosylation sites in proteins is often possible through a combination of proteolytic digestion, separation, mass spectrometry (MS) and tandem MS (MS/MS). Liquid chromatography (LC) in combination with MS/MS has been a reliable method for detecting glycopeptides in digestion mixtures, and for assigning glycosylation sites and glycopeptide sequences. Direct interfacing of LC with MS relies on electrospray ionization, which produces ions with two, three or four charges for most proteolytic peptides and glycopeptides. MS/MS spectra of such glycopeptide ions often lead to ambiguous interpretation if deconvolution to the singly charged level is not used. In contrast, the matrix-assisted laser desorption/ionization (MALDI) technique usually produces singly charged peptide and glycopeptide ions. These ions require an extended m/z range, as provided by the quadrupole-quadrupole time-of-flight (QqTOF) instrument used in these experiments, but the main advantages of studying singly charged ions are the simplicity and consistency of the MS/MS spectra. A first aim of the present study is to develop methods to recognize and use glycopeptide [M+H]+ ions as precursors for MS/MS, and thus for glycopeptide/glycoprotein identification as part of wider proteomics studies. Secondly, this article aims at demonstrating the usefulness of MALDI-MS/MS spectra of N-glycopeptides. Mixtures of diverse types of proteins, obtained commercially, were prepared and subjected to reduction, alkylation and tryptic digestion. Micro-column reversed-phase separation allowed deposition of several fractions on MALDI plates, followed by MS and MS/MS analysis of all peptides. Glycopeptide fractions were identified after MS by their specific m/z spacing patterns (162, 203, 291 u) between glycoforms, and then analyzed by MS/MS. In most cases, MS/MS spectra of [M+H]+ ions of glycopeptides featured peaks useful for determining sugar composition, peptide sequence, and thus probable glycosylation site. Peptide-related product ions could be used in database search procedures and allowed the identification of the glycoproteins. Copyright 2004 John Wiley & Sons, Ltd.

Structural dynamics of ribosome subunit association studied by mixing-spraying time-resolved cryo-EM

PubMed Central

Chen, Bo; Kaledhonkar, Sandip; Sun, Ming; Shen, Bingxin; Lu, Zonghuan; Barnard, David; Lu, Toh-Ming; Gonzalez, Ruben L.; Frank, Joachim

2015-01-01

Ribosomal subunit association is a key checkpoint in translation initiation, but its structural dynamics are poorly understood. Here, we used a recently developed mixing-spraying, time-resolved, cryogenic electron microscopy (cryo-EM) method to study ribosomal subunit association in the sub-second time range. We have improved this method and increased the cryo-EM data yield by tenfold. Pre-equilibrium states of the association reaction were captured by reacting the mixture of ribosomal subunits for 60 ms and 140 ms. We also identified three distinct ribosome conformations in the associated ribosomes. The observed proportions of these conformations are the same in these two time points, suggesting that ribosomes equilibrate among the three conformations within less than 60 ms upon formation. Our results demonstrate that the mixing-spraying method can capture multiple states of macromolecules during a sub-second reaction. Other fast processes, such as translation initiation, decoding and ribosome recycling, are amenable to study with this method. PMID:26004440

Spatiotemporal analysis of turbulent jets enabled by 100-kHz, 100-ms burst-mode particle image velocimetry

NASA Astrophysics Data System (ADS)

Miller, Joseph D.; Jiang, Naibo; Slipchenko, Mikhail N.; Mance, Jason G.; Meyer, Terrence R.; Roy, Sukesh; Gord, James R.

2016-12-01

100-kHz particle image velocimetry (PIV) is demonstrated using a double-pulsed, burst-mode laser with a burst duration up to 100 ms. This enables up to 10,000 time-sequential vector fields for capturing a temporal dynamic range spanning over three orders of magnitude in high-speed turbulent flows. Pulse doublets with inter-pulse spacing of 2 µs and repetition rate of 100 kHz are generated using a fiber-based oscillator and amplified through an all-diode-pumped, burst-mode amplifier. A physics-based model of pulse doublet amplification in the burst-mode amplifier is developed and used to accurately predict oscillator pulse width and pulse intensity inputs required to generate equal-energy pulse doublets at 532 nm for velocity measurements. The effect of PIV particle response and high-speed-detector limitations on the spatial and temporal resolution are estimated in subsonic turbulent jets. An effective spatial resolution of 266-275 µm and temporal resolution of 10 µs are estimated from the 8 × 8 pixel correlation window and inter-doublet time spacing, respectively. This spatiotemporal resolution is sufficient for quantitative assessment of integral time and length scales in highly turbulent jets with Reynolds numbers in the range 15,000-50,000. The temporal dynamic range of the burst-mode PIV measurement is 1200, limited by the 85-ms high-energy portion of the burst and 30-kHz high-frequency noise limit.

Leisure time activities of Iranian patients with multiple sclerosis: a qualitative study

PubMed Central

Hosseini, Seyed Mohammad Sadegh; Asgari, Ali; Rassafiani, Mehdi; Yazdani, Farzaneh; Mazdeh, Mehrdokht

2016-01-01

Background: Leisure time is one of the most important aspects of life, especially for people with chronic diseases. The concept and types of leisure have frequently been evaluated in different socio-cultural populations. The aim of this study was to identify the nature of leisure activities among a sample of Iranian patients with multiple sclerosis (MS) and classify the identified types of activities in the context of Iranian culture. Methods: In this qualitative study, semi-structured interview was applied to gather data from 34 MS patients that were selected through purposive sampling. The interviews were continued up to the point of saturation. Content analysis was used to explore experiences of the interviewees regarding their leisure activities. Results: Six categories of leisure activities were extracted for the studied patients with MS i.e.physical, social, individual, art/cultural, educational and spiritual/religious. Conclusion: The results represented the range and heterogeneity of leisure activities amongst the MS patients. Considering participation in spiritual/religious and social activities as leisure time undertaking might reflect cultural diversity in the perception and use of time for recreation. For mental health promotion purposes, paying special attention to the types of activities that people of different socio-cultural background choose for their refreshment could help health care providers in giving tailored advice for patients with MS and other chronic debilitating disease. PMID:27123437

A state-based probabilistic model for tumor respiratory motion prediction

NASA Astrophysics Data System (ADS)

Kalet, Alan; Sandison, George; Wu, Huanmei; Schmitz, Ruth

2010-12-01

This work proposes a new probabilistic mathematical model for predicting tumor motion and position based on a finite state representation using the natural breathing states of exhale, inhale and end of exhale. Tumor motion was broken down into linear breathing states and sequences of states. Breathing state sequences and the observables representing those sequences were analyzed using a hidden Markov model (HMM) to predict the future sequences and new observables. Velocities and other parameters were clustered using a k-means clustering algorithm to associate each state with a set of observables such that a prediction of state also enables a prediction of tumor velocity. A time average model with predictions based on average past state lengths was also computed. State sequences which are known a priori to fit the data were fed into the HMM algorithm to set a theoretical limit of the predictive power of the model. The effectiveness of the presented probabilistic model has been evaluated for gated radiation therapy based on previously tracked tumor motion in four lung cancer patients. Positional prediction accuracy is compared with actual position in terms of the overall RMS errors. Various system delays, ranging from 33 to 1000 ms, were tested. Previous studies have shown duty cycles for latencies of 33 and 200 ms at around 90% and 80%, respectively, for linear, no prediction, Kalman filter and ANN methods as averaged over multiple patients. At 1000 ms, the previously reported duty cycles range from approximately 62% (ANN) down to 34% (no prediction). Average duty cycle for the HMM method was found to be 100% and 91 ± 3% for 33 and 200 ms latency and around 40% for 1000 ms latency in three out of four breathing motion traces. RMS errors were found to be lower than linear and no prediction methods at latencies of 1000 ms. The results show that for system latencies longer than 400 ms, the time average HMM prediction outperforms linear, no prediction, and the more general HMM-type predictive models. RMS errors for the time average model approach the theoretical limit of the HMM, and predicted state sequences are well correlated with sequences known to fit the data.

Comparison of Different Ion Mobility Setups Using Poly (Ethylene Oxide) PEO Polymers: Drift Tube, TIMS, and T-Wave

NASA Astrophysics Data System (ADS)

Haler, Jean R. N.; Massonnet, Philippe; Chirot, Fabien; Kune, Christopher; Comby-Zerbino, Clothilde; Jordens, Jan; Honing, Maarten; Mengerink, Ynze; Far, Johann; Dugourd, Philippe; De Pauw, Edwin

2018-01-01

Over the years, polymer analyses using ion mobility-mass spectrometry (IM-MS) measurements have been performed on different ion mobility spectrometry (IMS) setups. In order to be able to compare literature data taken on different IM(-MS) instruments, ion heating and ion temperature evaluations have already been explored. Nevertheless, extrapolations to other analytes are difficult and thus straightforward same-sample instrument comparisons seem to be the only reliable way to make sure that the different IM(-MS) setups do not greatly change the gas-phase behavior. We used a large range of degrees of polymerization (DP) of poly(ethylene oxide) PEO homopolymers to measure IMS drift times on three different IM-MS setups: a homemade drift tube (DT), a trapped (TIMS), and a traveling wave (T-Wave) IMS setup. The drift time evolutions were followed for increasing polymer DPs (masses) and charge states, and they are found to be comparable and reproducible on the three instruments. [Figure not available: see fulltext.

Development and validation of a serum total testosterone liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay calibrated to NIST SRM 971.

PubMed

French, Deborah

2013-01-16

At our institution, serum testosterone in adult males is measured by immunoassay while female and pediatric specimens are sent to a reference laboratory for liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis due to low concentrations. As this is of significant cost, a testosterone LC-MS/MS assay was developed in-house. A 5500 QTRAP® using electrospray ionization and a Shimadzu Prominence with a C18 column were used. Gradient elution with formic acid, water and methanol:acetonitrile at 0.5 ml/min had a 7-min run-time. A liquid-liquid extraction with hexane:ethyl acetate was carried out on 200 μl of serum. Multiple reaction monitoring was employed. Sample preparation took ~80 min for 21 samples. Six calibrators were used (0-1263 ng/dl; concentration assigned by NIST SRM 971) with 3 quality controls (9, 168 and 532 ng/dl). The limits of detection and quantitation were 1 and 2 ng/dl respectively. Extraction recovery was ~90% and ion suppression ~5%. Within-run and total precision studies yielded <15% CV at the limit of quantitation and <7% CV through the rest of the linear range. Isobaric interferences were baseline separated from testosterone. Method comparisons between this assay, an immunoassay, and another LC-MS/MS assay were completed. An accurate and sensitive LC-MS/MS assay for total testosterone was developed. Bringing this assay in-house reduces turnaround time for clinicians and patients and saves our institution funds. Copyright © 2012 Elsevier B.V. All rights reserved.

A framework for intelligent data acquisition and real-time database searching for shotgun proteomics.

PubMed

Graumann, Johannes; Scheltema, Richard A; Zhang, Yong; Cox, Jürgen; Mann, Matthias

2012-03-01

In the analysis of complex peptide mixtures by MS-based proteomics, many more peptides elute at any given time than can be identified and quantified by the mass spectrometer. This makes it desirable to optimally allocate peptide sequencing and narrow mass range quantification events. In computer science, intelligent agents are frequently used to make autonomous decisions in complex environments. Here we develop and describe a framework for intelligent data acquisition and real-time database searching and showcase selected examples. The intelligent agent is implemented in the MaxQuant computational proteomics environment, termed MaxQuant Real-Time. It analyzes data as it is acquired on the mass spectrometer, constructs isotope patterns and SILAC pair information as well as controls MS and tandem MS events based on real-time and prior MS data or external knowledge. Re-implementing a top10 method in the intelligent agent yields similar performance to the data dependent methods running on the mass spectrometer itself. We demonstrate the capabilities of MaxQuant Real-Time by creating a real-time search engine capable of identifying peptides "on-the-fly" within 30 ms, well within the time constraints of a shotgun fragmentation "topN" method. The agent can focus sequencing events onto peptides of specific interest, such as those originating from a specific gene ontology (GO) term, or peptides that are likely modified versions of already identified peptides. Finally, we demonstrate enhanced quantification of SILAC pairs whose ratios were poorly defined in survey spectra. MaxQuant Real-Time is flexible and can be applied to a large number of scenarios that would benefit from intelligent, directed data acquisition. Our framework should be especially useful for new instrument types, such as the quadrupole-Orbitrap, that are currently becoming available.

A Framework for Intelligent Data Acquisition and Real-Time Database Searching for Shotgun Proteomics*

PubMed Central

Graumann, Johannes; Scheltema, Richard A.; Zhang, Yong; Cox, Jürgen; Mann, Matthias

2012-01-01

In the analysis of complex peptide mixtures by MS-based proteomics, many more peptides elute at any given time than can be identified and quantified by the mass spectrometer. This makes it desirable to optimally allocate peptide sequencing and narrow mass range quantification events. In computer science, intelligent agents are frequently used to make autonomous decisions in complex environments. Here we develop and describe a framework for intelligent data acquisition and real-time database searching and showcase selected examples. The intelligent agent is implemented in the MaxQuant computational proteomics environment, termed MaxQuant Real-Time. It analyzes data as it is acquired on the mass spectrometer, constructs isotope patterns and SILAC pair information as well as controls MS and tandem MS events based on real-time and prior MS data or external knowledge. Re-implementing a top10 method in the intelligent agent yields similar performance to the data dependent methods running on the mass spectrometer itself. We demonstrate the capabilities of MaxQuant Real-Time by creating a real-time search engine capable of identifying peptides “on-the-fly” within 30 ms, well within the time constraints of a shotgun fragmentation “topN” method. The agent can focus sequencing events onto peptides of specific interest, such as those originating from a specific gene ontology (GO) term, or peptides that are likely modified versions of already identified peptides. Finally, we demonstrate enhanced quantification of SILAC pairs whose ratios were poorly defined in survey spectra. MaxQuant Real-Time is flexible and can be applied to a large number of scenarios that would benefit from intelligent, directed data acquisition. Our framework should be especially useful for new instrument types, such as the quadrupole-Orbitrap, that are currently becoming available. PMID:22171319

Optimization of a direct analysis in real time/time-of-flight mass spectrometry method for rapid serum metabolomic fingerprinting.

PubMed

Zhou, Manshui; McDonald, John F; Fernández, Facundo M

2010-01-01

Metabolomic fingerprinting of bodily fluids can reveal the underlying causes of metabolic disorders associated with many diseases, and has thus been recognized as a potential tool for disease diagnosis and prognosis following therapy. Here we report a rapid approach in which direct analysis in real time (DART) coupled with time-of-flight (TOF) mass spectrometry (MS) and hybrid quadrupole TOF (Q-TOF) MS is used as a means for metabolomic fingerprinting of human serum. In this approach, serum samples are first treated to precipitate proteins, and the volatility of the remaining metabolites increased by derivatization, followed by DART MS analysis. Maximum DART MS performance was obtained by optimizing instrumental parameters such as ionizing gas temperature and flow rate for the analysis of identical aliquots of a healthy human serum samples. These variables were observed to have a significant effect on the overall mass range of the metabolites detected as well as the signal-to-noise ratios in DART mass spectra. Each DART run requires only 1.2 min, during which more than 1500 different spectral features are observed in a time-dependent fashion. A repeatability of 4.1% to 4.5% was obtained for the total ion signal using a manual sampling arm. With the appealing features of high-throughput, lack of memory effects, and simplicity, DART MS has shown potential to become an invaluable tool for metabolomic fingerprinting. 2010 American Society for Mass Spectrometry. Published by Elsevier Inc. All rights reserved.

Sensori-motor synchronisation variability decreases as the number of metrical levels in the stimulus signal increases.

PubMed

Madison, Guy

2014-03-01

Timing performance becomes less precise for longer intervals, which makes it difficult to achieve simultaneity in synchronisation with a rhythm. The metrical structure of music, characterised by hierarchical levels of binary or ternary subdivisions of time, may function to increase precision by providing additional timing information when the subdivisions are explicit. This hypothesis was tested by comparing synchronisation performance across different numbers of metrical levels conveyed by loudness of sounds, such that the slowest level was loudest and the fastest was softest. Fifteen participants moved their hand with one of 9 inter-beat intervals (IBIs) ranging from 524 to 3,125 ms in 4 metrical level (ML) conditions ranging from 1 (one movement for each sound) to 4 (one movement for every 8th sound). The lowest relative variability (SD/IBI<1.5%) was obtained for the 3 longest IBIs (1600-3,125 ms) and MLs 3-4, significantly less than the smallest value (4-5% at 524-1024 ms) for any ML 1 condition in which all sounds are identical. Asynchronies were also more negative with higher ML. In conclusion, metrical subdivision provides information that facilitates temporal performance, which suggests an underlying neural multi-level mechanism capable of integrating information across levels. © 2013.

A high SFDR 6-bit 20-MS/s SAR ADC based on time-domain comparator

NASA Astrophysics Data System (ADS)

Xue, Han; Hua, Fan; Qi, Wei; Huazhong, Yang

2013-08-01

This paper presents a 6-bit 20-MS/s high spurious-free dynamic range (SFDR) and low power successive approximation register analog to digital converter (SAR ADC) for the radio-frequency (RF) transceiver front-end, especially for wireless sensor network (WSN) applications. This ADC adopts the modified common-centroid symmetry layout and the successive approximation register reset circuit to improve the linearity and dynamic range. Prototyped in a 0.18-μm 1P6M CMOS technology, the ADC performs a peak SFDR of 55.32 dB and effective number of bits (ENOB) of 5.1 bit for 10 MS/s. At the sample rate of 20 MS/s and the Nyquist input frequency, the 47.39-dB SFDR and 4.6-ENOB are achieved. The differential nonlinearity (DNL) is less than 0.83 LSB and the integral nonlinearity (INL) is less than 0.82 LSB. The experimental results indicate that this SAR ADC consumes a total of 522 μW power and occupies 0.98 mm2.

The temperature dependence of the hydroxyl deuterium quadrupole coupling parameter and the rotational correlation time of the OD internuclear vector in neat ethanol-d

NASA Astrophysics Data System (ADS)

Ferris, Thomas D.; Farrar, Thomas C.

The temperature dependence of the hydroxyl proton chemical shift and deuterium quadrupolar relaxation time of neat ethanol were measured over the temperature range 190-350 K. The proton isotropic chemical shift varies from 6.2 ppm at 190 K to 4.7 ppm at 350 K. The deuterium NMR relaxation time in ethanol- d 1 varies from 6.2 ms to 309 ms over the same range. Ab initio calculations performed on various ethanol clusters ranging in size from monomer to hexamer show a linear correlation ( R 2 = 0.99) between ≤D, the deuterium quadrupole coupling parameter, and δH, the isotropic proton chemical shift in ppm relative to TMS: ≤D(kHz) = 297.60 - 15.28 δH. The temperature dependence of ≤D ranges from 199.5 kHz at 190 K to 221.4 kHz at 350 K. Using the values for ≤D and the relaxation time data, the temperature dependence of the OD rotational correlation time was found to vary from 282 ps at 190 K to 4.5 ps near the boiling point (350 K). Using these correlation times and bulk viscosity data, the Gierer-Wirtz model predicts a supramolecular cluster volume of about 317 A 3 , the approximate volume of a cyclic pentamer cluter of ethanol molecules. The cluster volume was nearly constant from 340 K to about 290 K.

Mortality from multiple sclerosis in British military personnel.

PubMed

Harris, E Clare; Palmer, Keith T; Cox, Vanessa; Darnton, Andrew; Osman, John; Coggon, David

2017-08-01

While analysing trends in occupational mortality in England and Wales, we noticed an unexpectedly elevated proportion of deaths from multiple sclerosis (MS) among men in the armed forces. To document and explore possible explanations for the observed excess. We analysed data on underlying cause of death and last full-time occupation for 3,688,916 deaths among men aged 20-74 years in England and Wales during 1979-2010, calculating proportional mortality ratios (PMRs) standardised for age. We compared PMRs for MS in the armed forces with those for each main social class, and in selected other occupations. We also compared PMRs for MS with those for motor neurone disease (MND). The overall PMR for MS in the armed forces during 1979-2010 was 243 (95%CI 203-288). The excess was apparent in each of three separate decades of study (PMRs, ranging from 220 to 259), and across the entire age range. PMRs for MS were not elevated to the same extent in comparator occupations, nor in any of the main social classes. There was no parallel increase in PMRs for MND. These findings suggest that the high proportional mortality from MS in British military personnel is unlikely to have occurred by chance, or as an artefact of the method of investigation. However, the only military cohort study with published results on MS does not support an increased risk. It would be useful to analyse data on MS from other established military cohorts, to check for evidence of a hazard. © The Author 2017. Published by Oxford University Press on behalf of the Society of Occupational Medicine.

Attribution of the discrepancy between ELISA and LC-MS/MS assay results of a PEGylated scaffold protein in post-dose monkey plasma samples due to the presence of anti-drug antibodies.

PubMed

Wang, Shujie J; Wu, Steven T; Gokemeijer, Jochem; Fura, Aberra; Krishna, Murli; Morin, Paul; Chen, Guodong; Price, Karen; Wang-Iverson, David; Olah, Timothy; Weiner, Russell; Tymiak, Adrienne; Jemal, Mohammed

2012-01-01

High-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) and enzyme-linked immunosorbent assay (ELISA) methods were developed for the quantification of a PEGylated scaffold protein drug in monkey plasma samples. The LC-MS/MS method was based on the extraction of the therapeutic protein with a water-miscible organic solvent and the subsequent trypsin digestion of the extract followed by the detection of a surrogate peptide. The assay was linear over a range of 10-3,000 ng/mL. The ELISA method utilized a therapeutic target-binding format in which the recombinant target antigen was used to capture the drug in the sample, followed by detection with an anti-PEG monoclonal antibody. The assay range was 30-2,000 ng/mL. A correlation study between the two methods was performed by measuring the drug concentrations in plasma samples from a single-dose pharmacokinetic (PK) study in cynomolgus monkeys following a 5-mg/kg subcutaneous administration (n = 4). In the early time points of the PK profile, the drug concentrations obtained by the LC-MS/MS method agreed very well with those obtained by the ELISA method. However, at later time points, the drug concentrations measured by the LC-MS/MS method were consistently higher than those measured by the ELISA method. The PK parameters calculated based on the concentration data showed that the two methods gave equivalent peak exposure (C(max)) at 24-48 h. However, the LC-MS/MS results exhibited about 1.53-fold higher total exposure (AUC(tot)) than the ELISA results. The discrepancy between the LC-MS/MS and ELISA results was investigated by conducting immunogenicity testing, anti-drug antibody (ADA) epitope mapping, and Western blot analysis of the drug concentrations coupled with Protein G separation. The results demonstrated the presence of ADA specific to the engineered antigen-binding region of the scaffold protein drug that interfered with the ability of the drug to bind to the target antigen used in the ELISA method. In the presence of the ADAs, the ELISA method measured only the active circulating drug (target-binding), while the LC-MS/MS method measured the total circulating drug. The work presented here indicates that the bioanalysis of protein drugs may be complicated owing to the presence of drug-binding endogenous components or ADAs in the post-dose (incurred) samples. The clear understanding of the behavior of different bioanalytical techniques vis-à-vis the potentially interfering components found in incurred samples is critical in selecting bioanalytical strategies for measuring protein drugs.

Pressurized solvent extraction followed by gas chromatography tandem mass spectrometry for the determination of benzotriazole light stabilizers in indoor dust.

PubMed

Carpinteiro, I; Abuín, B; Rodríguez, I; Ramil, M; Cela, R

2010-06-11

A novel and sensitive method for the determination of five benzotriazole compounds (commonly used as light stabilizers) in indoor dust is presented. Pressurized liquid extraction (PLE) and gas chromatography followed by tandem in time mass spectrometry (GC-MS/MS) were used as sample preparation and determination techniques, respectively. Extraction and clean-up were integrated on-line and, after an evaporative concentration step, the extract provided by the PLE instrument was injected directly in the GC-MS/MS system. Parameters affecting the performance of the sample preparation process were evaluated using experimental factorial designs. Under optimized conditions, analytes were recovered from 0.5g samples in 3 static extraction cycles of 10min, using a hexane:dichloromethane (7:3) mixture, at 90 degrees C. Silica (1g) was placed in the bottom of the extraction cells as clean-up sorbent. The recoveries of the method varied from 82 to 122%, with standard deviations below 13. The inter-day precision ranged from 9 to 12%, and the limits of quantification (LOQs) remained below 10ngg(-1) for all species. For the first time, four of the five investigated species were found in dust from indoor environments. Their mean concentrations ranged from 71 to 780ngg(-1). Copyright 2010 Elsevier B.V. All rights reserved.

[Determination of six plant growth regulator residues in strawberry by liquid chromatography-quadrupole time of flight mass spectrometry].

PubMed

Liu, Jingjing; Gong, Ping; Zhang, Xiaomei; Wang, Jianhua; Wang, Jingtang

2012-10-01

A novel method was established for the determination of six plant growth regulators (PGRs), 2,4-dichlorophenoxy acetic (2,4-D), 4-chlorophenoxy-acetic acid (CAP), 4-(3-indolyl)-butyric acid (BAA), forchlorfenuron (CPPU), abscisic acid (ABA) and trans-zeatin (ZT) in strawberry using liquid chromatography-quadrupole-time of flight mass spectrometry (LC-Q TOF MS). The Quick, Easy, Cheap, Effective, Rugged and Safe method (QuEChERS) has been validated for the extraction. In this QuEChERS method, the sample was extracted by acetonitrile and cleaned up with C18 adsorbent. The extract was measured directly by LC-Q TOF MS with electrospray ionization in negative mode. The compounds were separated on an Eclipse XDB-C8 column (150 mm x 4.6 mm, 5 microm) with acetonitrile-5 mmol/L ammonium acetate-0. 1% formic acid as mobile phase under gradient elution. The confirmatory analysis was carried out by determining the accurate masses of all compounds and fragment ions upon Target MS/MS. The limits of detection (LODs) were between 1 microg/kg and 5 microg/kg. The linear range was 0.005-1.0 mg/L for each analyte. The recoveries ranged from 87% to 107% with the relative standard deviations (RSDs) less than 10% (n = 6). The method was proved to be simple and accurate.

Synthesis of amino-functionalized silica nanoparticles for preparation of new laboratory standards

NASA Astrophysics Data System (ADS)

Alvarez-Toral, Aitor; Fernández, Beatriz; Malherbe, Julien; Claverie, Fanny; Pecheyran, Christophe; Pereiro, Rosario

2017-12-01

Platinum group elements (PGEs) are particularly interesting analytes in different fields, including environmental samples as well as high cost materials that contain them, such as for example automotive catalysts. This type of solid samples could be analysed by laser ablation (LA) coupled to ICP-MS, which allow to significantly reducing the analysis time since the time-consuming processes for sample preparation are not required. There is a considerable demand of standards with high PGEs concentration for quantification purposes, which cannot be carried out easily using LA-ICP-MS because the available standards (i.e. NIST SRM 61 × series) do not have such analytes in the same concentration range. In this paper, a new strategy is proposed for the synthesis of homogeneous laboratory standards with Pt, Pd and Rh concentrations that range from 77 μg/g of Pd up to 2035 μg/g of Rh. The proposed strategy is based on the synthesis of monodisperse amino-functionalized amorphous silica nanoparticles, which can retain metal ions. In addition to Pt, Pd and Rh, three lanthanides were also added to the nanoparticles (La, Ce, Nd). Sturdy pressed pellets can be made from the resulting nanopowder without the use of any binder. Elemental composition of standards made of nanoparticles was analysed by conventional nebulization ICP-MS and their homogeneity was successfully evaluated by LA-ICP-MS.

Oscillating and pulsed gradient diffusion magnetic resonance microscopy over an extended b-value range: implications for the characterization of tissue microstructure.

PubMed

Portnoy, S; Flint, J J; Blackband, S J; Stanisz, G J

2013-04-01

Oscillating gradient spin-echo (OGSE) pulse sequences have been proposed for acquiring diffusion data with very short diffusion times, which probe tissue structure at the subcellular scale. OGSE sequences are an alternative to pulsed gradient spin echo measurements, which typically probe longer diffusion times due to gradient limitations. In this investigation, a high-strength (6600 G/cm) gradient designed for small-sample microscopy was used to acquire OGSE and pulsed gradient spin echo data in a rat hippocampal specimen at microscopic resolution. Measurements covered a broad range of diffusion times (TDeff = 1.2-15.0 ms), frequencies (ω = 67-1000 Hz), and b-values (b = 0-3.2 ms/μm2). Variations in apparent diffusion coefficient with frequency and diffusion time provided microstructural information at a scale much smaller than the imaging resolution. For a more direct comparison of the techniques, OGSE and pulsed gradient spin echo data were acquired with similar effective diffusion times. Measurements with similar TDeff were consistent at low b-value (b < 1 ms/μm(2) ), but diverged at higher b-values. Experimental observations suggest that the effective diffusion time can be helpful in the interpretation of low b-value OGSE data. However, caution is required at higher b, where enhanced sensitivity to restriction and exchange render the effective diffusion time an unsuitable representation. Oscillating and pulsed gradient diffusion techniques offer unique, complementary information. In combination, the two methods provide a powerful tool for characterizing complex diffusion within biological tissues. Copyright © 2012 Wiley Periodicals, Inc.

Desirability and expectations of the UK MS Register: views of people with MS.

PubMed

Osborne, Lisa A; Middleton, Rodden M; Jones, Kerina H; Ford, David V; Noble, J Gareth

2013-11-01

Internet-based health registers are increasingly commonly used for health promotion and medical research, yet little is known about what the patient groups who help form the basis of such registers expect from these tools. Mismatches between patient expectations and the register design may limit the long-term utility of such registers. This study elicited the views of people with Multiple Sclerosis (PwMS) on the desirability and expectations regarding a UK Register for MS. Participants were recruited through a range of traditional means (newsletters, adverts, word of mouth), as well as via the Internet, to obtain a broad sample of PwMS. Semi-structured interviews were conducted over the telephone, and the questions asked about: the desirability of the Register; what the participants envisaged the Register actually being used for; and what they hoped the Register could be used for. The majority of individuals' points postulated that a UK MS Register would be useful, but a range of potential concerns were identified by the sample, such as security, accessibility for all PwMS, and the validity of self-report data. Analysis of the responses revealed a difference between what PwMS thought the Register would be used for, and how they wanted it to be used, particularly in relation to a desired social contact, exchange, and networking function. The security and accessibility of the website, the validity of the data, and mismatches between the expected and actual uses, are all issues of importance in the development of e-health tools, if PwMS are to be successfully engaged over time. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Analyses of gibberellins in coconut (Cocos nucifera L.) water by partial filling-micellar electrokinetic chromatography-mass spectrometry with reversal of electroosmotic flow.

PubMed

Ge, Liya; Yong, Jean Wan Hong; Tan, Swee Ngin; Hua, Lin; Ong, Eng Shi

2008-05-01

In this paper, we present the results of simultaneous screening of eight gibberellins (GAs) in coconut (Cocos nucifera L.) water by MEKC directly coupled to ESI-MS detection. During the development of MEKC-MS, partial filling (PF) was used to prevent the micelles from reaching the mass spectrometer as this is detrimental to the MS signal, and a cationic surfactant, cetyltrimethylammonium hydroxide, was added to the electrolyte to reverse the EOF. On the basis of the resolution of the neighboring peaks, different parameters (i.e., the pH and concentration of buffer, surfactant concentrations, length of the injected micellar plug, organic modifier, and applied separation voltage) were optimized to achieve a satisfactory PF-MEKC separation of eight GA standards. Under optimum conditions, a baseline separation of GA standards, including GA1, GA3, GA5, GA6, GA7, GA9, GA12, and GA13, was accomplished within 25 min. Satisfactory results were obtained in terms of precision (RSD of migration time below 0.9%), sensitivity (LODs in the range of 0.8-1.9 microM) and linearity (R2 between 0.981 and 0.997). MS/MS with multiple reaction monitoring (MRM) detection was carried out to obtain sufficient selectivity. PF-MEKC-MS/MS allowed the direct identification and confirmation of the GAs presented in coconut water (CW) sample after SPE, while, the quantitative analysis of GAs was performed by PF-MEKC-MS approach. GA1 and GA3 were successfully detected and quantified in CW. It is anticipated that the current PF-MEKC-MS method can be applicable to analyze GAs in a wide range of biological samples.

Next generation offline approaches to trace organic compound speciation: Approaching comprehensive speciation with soft ionization and very high resolution tandem mass spectrometry

NASA Astrophysics Data System (ADS)

Khare, P.; Marcotte, A.; Sheu, R.; Ditto, J.; Gentner, D. R.

2017-12-01

Intermediate- and semi-volatile organic compounds (IVOCs and SVOCs) have high secondary organic aerosol (SOA) yields, as well as significant ozone formation potentials. Yet, their emission sources and oxidation pathways remain largely understudied due to limitations in current analytical capabilities. Online mass spectrometers are able to collect real time data but their limited mass resolving power renders molecular level characterization of IVOCs and SVOCs from the unresolved complex mixture unfeasible. With proper sampling techniques and powerful analytical instrumentation, our offline tandem mass spectrometry (i.e. MS×MS) techniques provide molecular-level and structural identification over wide polarity and volatility ranges. We have designed a novel analytical system for offline analysis of gas-phase SOA precursors collected on custom-made multi-bed adsorbent tubes. Samples are desorbed into helium via a gradual temperature ramp and sample flow is split equally for direct-MS×MS analysis and separation via gas chromatography (GC). The effluent from GC separation is split again for analysis via atmospheric pressure chemical ionization quadrupole time-of-flight mass spectrometry (APCI-Q×TOF) and traditional electron ionization mass spectrometry (EI-MS). The compounds for direct-MS×MS analysis are delivered via a transfer line maintained at 70ºC directly to APCI-Q×TOF, thus preserving the molecular integrity of thermally-labile, or other highly-reactive, organic compounds. Both our GC-MS×MS and direct-MS×MS analyses report high accuracy parent ion masses as well as information on molecular structure via MS×MS, which together increase the resolution of unidentified complex mixtures. We demonstrate instrument performance and present preliminary results from urban atmospheric samples collected from New York City with a wide range of compounds including highly-functionalized organic compounds previously understudied in outdoor air. Our work offers new insights into emerging emission sources in urban environments that can have a major impact on public health and also improves understanding of anthropogenic SOA precursor emissions.

Stir bar sorptive extraction combined with high performance liquid chromatography-ultraviolet/inductively coupled plasma mass spectrometry for analysis of thyroxine in urine samples.

PubMed

Fan, Wenying; Mao, Xiangju; He, Man; Chen, Beibei; Hu, Bin

2013-11-29

tIn this work, polyethyleneglycol (PEG)/hydroxyl polydimethylsiloxane (OH-PDMS)/γ -mercaptopropyltrimethoxysilane (γ -MPTS) coated stir bar was prepared by sol–gel process and its extraction performance for the extraction of amphoteric thyroxines (3,3',5,5'-tetraiodothyronin, T(4); 3,3',5-triiodothyronine, T(3); reversed-3,3',5-triiodothyronine, rT(3)) and their metabolite (3,5-diiodothyronine,T2) was studied. The preparation reproducibility of PEG/OH-PDMS/γ -MPTS coated stir bar was investigated, and the relative standard deviations (RSDs) in the same batch and among different batches were 3.3–14.3% (n = 5) and 7.7–16.6% (n = 3), respectively. The prepared PEG/OH-PDMS/γ -MPTS coated stir bar could be reused for more than 20 times. Based on this fact, a novel method of stir bar sorptive extraction (SBSE) combined with high performance liquid chromatography (HPLC)-ultraviolet (UV)and HPLC-inductively coupled plasma mass spectrometry (ICP-MS) for the analysis of target thyroxinesin human urine samples was developed. The influencing factors of SBSE, such as sample pH, extraction time, stirring rate, salt effect, desorption solution and desorption time, were studied in detail, and the analytical performance of the proposed method was evaluated under the optimized conditions. The enrichment factors (EFs) of the developed method for four target thyroxines were in the range of 14.9–70.4(theoretical enrichment factor was 100). The RSDs were ranging from 4.0% to 13.8% for SBSE-HPLC-UV (c = 25 μg/L, n = 6) and from 3.7% to 6.1% for SBSE-HPLC-ICP-MS (c = 0.5 μg/L, n = 5). The linear range obtained by SBSE-HPLC-UV was 2–500 μg/L for T(2)and 5–500 μg/L for rT3, T(3)and T(4), with correlation coefficients (r) ranging from 0.9957 to 0.9998, respectively, while the linear range obtained by SBSE-HPLC-ICP-MS was 0.05–500 μg/L for T(2) and rT(3), 0.10–200 μg/L for T(3) and 0.05–200 μg/L for T(4)with r ranging from 0.9979 to 0.9998, respectively. The limits of detection (LODs) for the target thyroxines were 0.60–2.20 μg/L for SBSE-HPLC-UV and 0.0071–0.0355 μg/L SBSE-HPLC-ICP-MS, respectively. The developed method was applied for the determination of target thyroxines in urine samples, and the recovery for the spiking samples obtained by SBSE-HPLC-UV was in the range of 81.6–137.6% for human urine,while the recovery for the spiking urine samples obtained by SBSE-HPLC-ICP-MS were in the range of 72.0–121.5%.

Automated saliva processing for LC-MS/MS: Improving laboratory efficiency in cortisol and cortisone testing.

PubMed

Antonelli, Giorgia; Padoan, Andrea; Artusi, Carlo; Marinova, Mariela; Zaninotto, Martina; Plebani, Mario

2016-04-01

The aim of this study was to implement in our routine practice an automated saliva preparation protocol for quantification of cortisol (F) and cortisone (E) by LC-MS/MS using a liquid handling platform, maintaining the previously defined reference intervals with the manual preparation. Addition of internal standard solution to saliva samples and calibrators and SPE on μ-elution 96-well plate were performed by liquid handling platform. After extraction, the eluates were submitted to LC-MS/MS analysis. The manual steps within the entire process were to transfer saliva samples in suitable tubes, to put the cap mat and transfer of the collection plate to the LC auto sampler. Transference of the reference intervals from the manual to the automated procedure was established by Passing Bablok regression on 120 saliva samples analyzed simultaneously with the two procedures. Calibration curves were linear throughout the selected ranges. The imprecision ranged from 2 to 10%, with recoveries from 95 to 116%. Passing Bablok regression demonstrated no significant bias. The liquid handling platform translates the manual steps into automated operations allowing for saving hands-on time, while maintaining assay reproducibility and ensuring reliability of results, making it implementable in our routine with the previous established reference intervals. Copyright © 2015 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.

CE-MS analysis of heroin and its basic impurities using a charged polymer-protected gold nanoparticle-coated capillary.

PubMed

Zhang, Zhengxiang; Yan, Bo; Liu, Kelin; Liao, Yiping; Liu, Huwei

2009-01-01

The first application of charged polymer-protected gold nanoparticles (Au NPs) as semi-permanent capillary coating in CE-MS was presented. Poly(diallyldimethylammonium chloride) (PDDA) was the only reducing and stabilizing agent for Au NPs preparation. Stable and repeatable coating with good tolerance to 0.1 M HCl, methanol, and ACN was obtained via a simple rinsing procedure. Au NPs enhanced the coating stability toward flushing by methanol, improved the run-to-run and capillary-to-capillary repeatabilities, and improved the separation efficiency of heroin and its basic impurities for tracing geographical origins of illicit samples. Baseline resolution of eight heroin-related alkaloids was achieved on the PDDA-protected Au NPs-coated capillary under the optimum conditions: 120 mM ammonium acetate (pH 5.2) with addition of 13% methanol, separation temperature 20 degrees C, applied voltage -20 kV, and capillary effective length 60.0 cm. CE-MS analysis with run-to-run RSDs (n=5) of migration time in the range of 0.43-0.62% and RSDs (n=5) of peak area in the range of 1.49-4.68% was obtained. The established CE-MS method would offer sensitive detection and confident identification of heroin and related compounds and provide an alternative to LC-MS and GC-MS for illicit drug control.

Buffer salt effects in off-line coupling of capillary electrophoresis and mass spectrometry.

PubMed

Marák, Jozef; Stanová, Andrea

2014-05-01

In this work, the impact of buffer salts/matrix effects on the signal in direct injection MS with an electrospray interface (DI-ESI-MS) following pITP fractionation of the sample was studied. A range of buffers frequently used in CE analyses (pH 3-10) was prepared containing 10, 50, and 90% v/v of ACN, respectively. The sets of calibration solutions of cetirizine (an antihistaminic drug with an amphiprotic character) within a 0.05-2.0 mg/L concentration range were prepared in different buffers. The greatest enhancements in the MS signal (in terms of change in the slope of the calibration line) were obtained for the beta-alanine buffer (pH 3.5) in positive ionization and for the borate buffer (pH 9.2) in negative ionization, respectively. The procedure was successfully applied to the analysis of buserelin (a peptidic drug). The slope of the calibration line for solutions containing the beta-alanine buffer with 50% of ACN was 4 times higher than for water or urine, respectively. This study clearly demonstrates that the buffer salt/matrix effects in an offline combination of pITP and DI-ESI-MS can also play a positive role, as they can enhance the signal in MS. A similar influence of the above effects can also be presumed in the CE techniques combined on-line with ESI-MS.

Quantification of amlodipine and atorvastatin in human plasma by UPLC-MS/MS method and its application to a bioequivalence study.

PubMed

Rezk, Mamdouh R; Badr, Kamal A

2018-07-01

A robust, rapid and sensitive UPLC-MS/MS method has been developed, optimized and validated for the determination of amlodipine (AML) and atorvastatin (ATO) in human plasma using eplerenone as an internal standard (IS). Multiple-reaction monitoring in positive electrospray ionization mode was utilized in Xevo TQD LC-MS/MS. Double extraction was used in sample preparation using diethyl ether and ethyl acetate. The prepared samples were analyzed using an Acquity UPLC BEH C 18 (50 × 2.1 mm, 1.7 μm) column. Ammonium formate and acetonitrile, pumped isocraticaly at a flow rate of 0.25 mL/min, were used as a mobile phase. Method validation was done as per the US Food and Drug Administration guidelines. Linearity was achieved in the range of 0.1-10 ng/mL for AML and 0.05-50 ng/mL for ATO. Intra-day and inter-day accuracy and precision were calculated and found to be within the acceptable range. A short run time, of <1.5 min, permits analysis of a large number of plasma samples per batch. The developed and validated method was applied to estimate AML and ATO in a bioequivalence study in healthy human volunteers. Copyright © 2018 John Wiley & Sons, Ltd.

An improved pseudotargeted metabolomics approach using multiple ion monitoring with time-staggered ion lists based on ultra-high performance liquid chromatography/quadrupole time-of-flight mass spectrometry.

PubMed

Wang, Yang; Liu, Fang; Li, Peng; He, Chengwei; Wang, Ruibing; Su, Huanxing; Wan, Jian-Bo

2016-07-13

Pseudotargeted metabolomics is a novel strategy integrating the advantages of both untargeted and targeted methods. The conventional pseudotargeted metabolomics required two MS instruments, i.e., ultra-high performance liquid chromatography/quadrupole-time- of-flight mass spectrometry (UHPLC/Q-TOF MS) and UHPLC/triple quadrupole mass spectrometry (UHPLC/QQQ-MS), which makes method transformation inevitable. Furthermore, the picking of ion pairs from thousands of candidates and the swapping of the data between two instruments are the most labor-intensive steps, which greatly limit its application in metabolomic analysis. In the present study, we proposed an improved pseudotargeted metabolomics method that could be achieved on an UHPLC/Q-TOF/MS instrument operated in the multiple ion monitoring (MIM) mode with time-staggered ion lists (tsMIM). Full scan-based untargeted analysis was applied to extract the target ions. After peak alignment and ion fusion, a stepwise ion picking procedure was used to generate the ion lists for subsequent single MIM and tsMIM. The UHPLC/Q-TOF tsMIM MS-based pseudotargeted approach exhibited better repeatability and a wider linear range than the UHPLC/Q-TOF MS-based untargeted metabolomics method. Compared to the single MIM mode, the tsMIM significantly increased the coverage of the metabolites detected. The newly developed method was successfully applied to discover plasma biomarkers for alcohol-induced liver injury in mice, which indicated its practicability and great potential in future metabolomics studies. Copyright © 2016 Elsevier B.V. All rights reserved.

Identification and quantification of carotenoids, by HPLC-PDA-MS/MS, from Amazonian fruits.

PubMed

de Rosso, Veridiana V; Mercadante, Adriana Z

2007-06-27

The major and minor carotenoids from six fruits, buriti (Mauritia vinifera), mamey (Mammea americana), marimari (Geoffrola striata), peach palm (Bactrys gasipaes), physalis (Physalis angulata), and tucuma (Astrocaryum aculeatum), all native to the Amazonia region, were determined by high-performance liquid chromatography-photodiode array detector-mass spectrometry detector (HPLC-PDA-MS/MS), fulfilling the recommended criteria for identification. A total of 60 different carotenoids were separated on a C30 column, all-trans-beta-carotene being the major carotenoid found in all fruits. The presence of apo-10'-beta-carotenol, found in mamey, was not previously reported in foods. In addition, this is the first time that the identification of beta-zeacarotene in natural sources is supported by MS data. The total carotenoid content ranged from 38 microg/g in marimari to 514 microg/g in buriti. All fruits analyzed can be considered good sources of provitamin A, especially buriti, with 7280 RE/100 g.

Detection of lysergic acid diethylamide (LSD) in urine by gas chromatography-ion trap tandem mass spectrometry.

PubMed

Sklerov, J H; Kalasinsky, K S; Ehorn, C A

1999-10-01

A confirmatory method for the detection and quantitation of lysergic acid diethylamide (LSD) is presented. The method employs gas chromatography-tandem mass spectrometry (GC-MS-MS) using an internal ionization ion trap detector for sensitive MS-MS-in-time measurements of LSD extracted from urine. Following a single-step solid-phase extraction of 5 mL of urine, underivatized LSD can be measured with limits of quantitation and detection of 80 and 20 pg/mL, respectively. Temperature-programmed on-column injections of urine extracts were linear over the concentration range 20-2000 pg/mL (r2 = 0.999). Intraday and interday coefficients of variation were < 6% and < 13%, respectively. This procedure has been applied to quality-control specimens and LSD-positive samples in this laboratory. Comparisons with alternate GC-MS methods and extraction procedures are discussed.

The use of Gram stain and matrix-assisted laser desorption ionization time-of-flight mass spectrometry on positive blood culture: synergy between new and old technology.

PubMed

Fuglsang-Damgaard, David; Nielsen, Camilla Houlberg; Mandrup, Elisabeth; Fuursted, Kurt

2011-10-01

Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) is promising as an alternative to more costly and cumbersome methods for direct identifications in blood cultures. We wanted to evaluate a simplified pre-treatment method for using MALDI-TOF-MS directly on positive blood cultures using BacT/Alert blood culture system, and to test an algorithm combining the result of the initial microscopy with the result suggested by MALDI-TOF-MS. Using the recommended cut-off score of 1.7 the best results were obtained among Gram-negative rods with correct identifications in 91% of Enterobacteriaceae, 83% in aerobic/non-fermentative Gram-negative rods, whereas results were more modest among Gram-positive cocci with correct identifications in 52% of Staphylococci, 54% in Enterococci and only 20% in Streptococci. Combining the results of Gram stain with the top reports by MALDI-TOF-MS, increased the sensitivity from 91% to 93% in the score range from 1.5 to 1.7 and from 48% to 85% in the score range from 1.3 to 1.5. Thus, using this strategy and accepting a cut-off at 1.3 instead of the suggested 1.7, overall sensitivity could be increased from 88.1% to 96.3%. MALDI-TOF-MS is an efficient method for direct routine identification of bacterial isolates in blood culture, especially when combined with the result of the Gram stain. © 2011 The Authors. APMIS © 2011 APMIS.

Gas chromatography and ultra high performance liquid chromatography tandem mass spectrometry methods for the determination of selected endocrine disrupting chemicals in human breast milk after stir-bar sorptive extraction.

PubMed

Rodríguez-Gómez, R; Zafra-Gómez, A; Camino-Sánchez, F J; Ballesteros, O; Navalón, A

2014-07-04

In the present work, two specific, accurate and sensitive methods for the determination of endocrine disrupting chemicals (EDCs) in human breast milk are developed and validated. Bisphenol A and its main chlorinated derivatives, five benzophenone-UV filters and four parabens were selected as target analytes. The method involves a stir-bar sorptive extraction (SBSE) procedure followed by a solvent desorption prior to GC-MS/MS or UHPLC-MS/MS analysis. A derivatization step is also necessary when GC analysis is performed. The GC column used was a capillary HP-5MS with a run time of 26min. For UHPLC analysis, the stationary phase was a non-polar Acquity UPLC(®) BEH C18 column and the run time was 10min. In both cases, the analytes were detected and quantified using a triple quadrupole mass spectrometer (QqQ). Quality parameters such as linearity, accuracy (trueness and precision), sensitivity and selectivity were examined and yielded good results. The limits of quantification (LOQs) ranged from 0.3 to 5.0ngmL(-1) for GC and from 0.2 to 1.0ngmL(-1) for LC. The relative standard deviation (RSD) was lower than 15% and the recoveries ranged from 92 to 114% in all cases, being slightly unfavorable the results obtained with LC. The methods were satisfactorily applied for the determination of target compounds in human milk samples from 10 randomly selected women. Copyright © 2014 Elsevier B.V. All rights reserved.

Determination of doping peptides via solid-phase microelution and accurate-mass quadrupole time-of-flight LC-MS.

PubMed

Cuervo, Darío; Loli, Cynthia; Fernández-Álvarez, María; Muñoz, Gloria; Carreras, Daniel

2017-10-15

A complete analytical protocol for the determination of 25 doping-related peptidic drugs and 3 metabolites in urine was developed by means of accurate-mass quadrupole time-of-flight (Q-TOF) LC-MS analysis following solid-phase extraction (SPE) on microplates and conventional SPE pre-treatment for initial testing and confirmation, respectively. These substances included growth hormone releasing factors, gonadotropin releasing factors and anti-diuretic hormones, with molecular weights ranging from 540 to 1320Da. Optimal experimental conditions were stablished after investigation of different parameters concerning sample preparation and instrumental analysis. Weak cation exchange SPE followed by C18 HPLC chromatography and accurate mass detection provided the required sensitivity and selectivity for all the target peptides under study. 2mg SPE on 96-well microplates can be used in combination with full scan MS detection for the initial testing, thus providing a fast, cost-effective and high-throughput protocol for the processing of a large batch of samples simultaneously. On the other hand, extraction on 30mg SPE cartridges and subsequent target MS/MS determination was the protocol of choice for confirmatory purposes. The methodology was validated in terms of selectivity, recovery, matrix effect, precision, sensitivity (limit of detection, LOD), cross contamination, carryover, robustness and stability. Recoveries ranged from 6 to 70% (microplates) and 17-95% (cartridges), with LODs from 0.1 to 1ng/mL. The suitability of the method was assessed by analyzing different spiked or excreted urines containing some of the target substances. Copyright © 2017 Elsevier B.V. All rights reserved.

Identification and absolute quantification of enzymes in laundry detergents by liquid chromatography tandem mass spectrometry.

PubMed

Gaubert, Alexandra; Jeudy, Jérémy; Rougemont, Blandine; Bordes, Claire; Lemoine, Jérôme; Casabianca, Hervé; Salvador, Arnaud

2016-07-01

In a stricter legislative context, greener detergent formulations are developed. In this way, synthetic surfactants are frequently replaced by bio-sourced surfactants and/or used at lower concentrations in combination with enzymes. In this paper, a LC-MS/MS method was developed for the identification and quantification of enzymes in laundry detergents. Prior to the LC-MS/MS analyses, a specific sample preparation protocol was developed due to matrix complexity (high surfactant percentages). Then for each enzyme family mainly used in detergent formulations (protease, amylase, cellulase, and lipase), specific peptides were identified on a high resolution platform. A LC-MS/MS method was then developed in selected reaction monitoring (SRM) MS mode for the light and corresponding heavy peptides. The method was linear on the peptide concentration ranges 25-1000 ng/mL for protease, lipase, and cellulase; 50-1000 ng/mL for amylase; and 5-1000 ng/mL for cellulase in both water and laundry detergent matrices. The application of the developed analytical strategy to real commercial laundry detergents enabled enzyme identification and absolute quantification. For the first time, identification and absolute quantification of enzymes in laundry detergent was realized by LC-MS/MS in a single run. Graphical Abstract Identification and quantification of enzymes by LC-MS/MS.

Measurement of free carnitine and acylcarnitines in plasma by HILIC-ESI-MS/MS without derivatization.

PubMed

Peng, Minzhi; Liu, Li; Jiang, Minyan; Liang, Cuili; Zhao, Xiaoyuan; Cai, Yanna; Sheng, Huiying; Ou, Zhiying; Luo, Hong

2013-08-01

Measurement of carnitine and acylcarnitines in plasma is important in diagnosis of fatty acid β-oxidation disorders and organic acidemia. The usual method uses flow injection tandem mass spectrometry (FIA-MS/MS), which has limitations. A rapid and more accurate method was developed to be used for high-risk screening and diagnosis. Carnitine and acylcarnitines were separated by hydrophilic interaction liquid chromatography (HILIC) without derivatization and detected with a QTRAP MS/MS System. Total analysis time was 9.0min. The imprecision of within- and between-run were less than 6% and 17%, respectively. Recoveries were in the range of 85-110% at three concentrations. Some acylcarnitine isomers could be separated, such as dicarboxylic and hydroxyl acylcarnitines. The method could also separate interferent to avoid false positive results. 216 normal samples and 116 patient samples were detected with the validated method, and 49 patients were identified with fatty acid oxidation disorders or organic acidemias. Copyright © 2013 Elsevier B.V. All rights reserved.

Patterns of Objective and Subjective Burden of Informal Caregivers in Multiple Sclerosis.

PubMed

Bayen, E; Papeix, C; Pradat-Diehl, P; Lubetzki, C; Joël, M E

2015-01-01

Home care for patients with Multiple Sclerosis (MS) relies largely on informal caregivers (ICs). Methods. We assessed ICs objective burden (Resource Utilization in Dementia measuring informal care time (ICT)) and ICs subjective burden (Zarit Burden Inventory (ZBI)). ICs (N = 99) were spouses (70%), mean age 52 years, assisting disabled patients with a mean EDSS (Expanded Disability Status Scale) of 5.5, with executive dysfunction (mean DEX (Dysexecutive questionnaire) of 25) and a duration of MS ranging from 1 to 44 years. burden was high (mean ICT = 6.5 hours/day), mostly consisting of supervision time. Subjective burden was moderate (mean ZBI = 27.3). Multivariate analyses showed that both burdens were positively correlated with higher levels of EDSS and DEX, whereas coresidency and IC's female gender correlated with objective burden only and IC's poor mental health status with subjective burden only. When considering MS aggressiveness, it appeared that both burdens were not correlated with a higher duration of MS but rather increased for patients with severe and early dysexecutive function and for patients classified as fast progressors according to the Multiple Sclerosis Severity Score. Evaluation of MS disability course and IC's personal situation is crucial to understand the burden process and to implement adequate interventions in MS.

Electric propulsion options for 10 kW class earth space missions

NASA Technical Reports Server (NTRS)

Patterson, M. J.; Curran, Francis M.

1989-01-01

Five and 10 kW ion and arcjet propulsion system options for a near-term space demonstration experiment have been evaluated. Analyses were conducted to determine first-order propulsion system performance and system component mass estimates. Overall mission performance of the electric propulsion systems was quantified in terms of the maximum thrusting time, total impulse, and velocity increment capability available when integrated onto a generic spacecraft under fixed mission model assumptions. Maximum available thrusting times for the ion-propelled spacecraft options, launched on a DELTA II 6920 vehicle, range from approximately 8,600 hours for a 4-engine 10 kW system to more than 29,600 hours for a single-engine 5 kW system. Maximum total impulse values and maximum delta-v's range from 1.2x10(7) to 2.1x10(7) N-s, and 3550 to 6200 m/s, respectively. Maximum available thrusting times for the arcjet propelled spacecraft launched on the DELTA II 6920 vehicle range from approximately 528 hours for the 6-engine 10 kW hydrazine system to 2328 hours for the single-engine 5 kW system. Maximum total impulse values and maximum delta-v's range from 2.2x10(6) to 3.6x10(6) N-s, and approximately 662 to 1072 m/s, respectively.

Estimating uncertainty in subsurface glider position using transmissions from fixed acoustic tomography sources.

PubMed

Van Uffelen, Lora J; Nosal, Eva-Marie; Howe, Bruce M; Carter, Glenn S; Worcester, Peter F; Dzieciuch, Matthew A; Heaney, Kevin D; Campbell, Richard L; Cross, Patrick S

2013-10-01

Four acoustic Seagliders were deployed in the Philippine Sea November 2010 to April 2011 in the vicinity of an acoustic tomography array. The gliders recorded over 2000 broadband transmissions at ranges up to 700 km from moored acoustic sources as they transited between mooring sites. The precision of glider positioning at the time of acoustic reception is important to resolve the fundamental ambiguity between position and sound speed. The Seagliders utilized GPS at the surface and a kinematic model below for positioning. The gliders were typically underwater for about 6.4 h, diving to depths of 1000 m and traveling on average 3.6 km during a dive. Measured acoustic arrival peaks were unambiguously associated with predicted ray arrivals. Statistics of travel-time offsets between received arrivals and acoustic predictions were used to estimate range uncertainty. Range (travel time) uncertainty between the source and the glider position from the kinematic model is estimated to be 639 m (426 ms) rms. Least-squares solutions for glider position estimated from acoustically derived ranges from 5 sources differed by 914 m rms from modeled positions, with estimated uncertainty of 106 m rms in horizontal position. Error analysis included 70 ms rms of uncertainty due to oceanic sound-speed variability.

Low-back electromyography (EMG) data-driven load classification for dynamic lifting tasks.

PubMed

Totah, Deema; Ojeda, Lauro; Johnson, Daniel D; Gates, Deanna; Mower Provost, Emily; Barton, Kira

2018-01-01

Numerous devices have been designed to support the back during lifting tasks. To improve the utility of such devices, this research explores the use of preparatory muscle activity to classify muscle loading and initiate appropriate device activation. The goal of this study was to determine the earliest time window that enabled accurate load classification during a dynamic lifting task. Nine subjects performed thirty symmetrical lifts, split evenly across three weight conditions (no-weight, 10-lbs and 24-lbs), while low-back muscle activity data was collected. Seven descriptive statistics features were extracted from 100 ms windows of data. A multinomial logistic regression (MLR) classifier was trained and tested, employing leave-one subject out cross-validation, to classify lifted load values. Dimensionality reduction was achieved through feature cross-correlation analysis and greedy feedforward selection. The time of full load support by the subject was defined as load-onset. Regions of highest average classification accuracy started at 200 ms before until 200 ms after load-onset with average accuracies ranging from 80% (±10%) to 81% (±7%). The average recall for each class ranged from 69-92%. These inter-subject classification results indicate that preparatory muscle activity can be leveraged to identify the intent to lift a weight up to 100 ms prior to load-onset. The high accuracies shown indicate the potential to utilize intent classification for assistive device applications. Active assistive devices, e.g. exoskeletons, could prevent back injury by off-loading low-back muscles. Early intent classification allows more time for actuators to respond and integrate seamlessly with the user.

A novel metal-organic framework composite MIL-101(Cr)@GO as an efficient sorbent in dispersive micro-solid phase extraction coupling with UHPLC-MS/MS for the determination of sulfonamides in milk samples.

PubMed

Jia, Xiuna; Zhao, Pan; Ye, Xiu; Zhang, Lianjun; Wang, Ting; Chen, Qinyu; Hou, Xiaohong

2017-07-01

As a novel material, metal-organic framework/graphite oxide (MIL-101(Cr)@GO) has great potential for the pretreatment of trace analytes. In the present study, MIL-101(Cr)@GO was synthesized using a solvothermal synthesis method at the nanoscale and was applied as sorbent in the dispersive micro-solid phase extraction (DMSPE) for the enrichment of the trace sulfonamides (SAs) from milk samples for the first time. Several experimental parameters including kinds of sorbents, the effect of pH, the amount of MIL-101(Cr)@GO, ionic strength, adsorption time, desorption solvent and desorption time were investigated. Under the optimal conditions, the linear ranges were from 0.1 to 10μg/L, 0.2-20μg/L or 0.5-50μg/L for the analytes with regression coefficients (r) from 0.9942 to 0.9999. The limits of detection were between 0.012 and 0.145μg/L. The recoveries ranged from 79.83% to 103.8% with relative standard deviations (RSDs)<10% (n=3). MIL-101(Cr)@GO exhibited remarkable advantages compared to MIL-101(Cr), MIL-100(Fe), activated carbon and other sorbent materials used in pretreatment methods. A simple, rapid, sensitive, inexpensive and less solvent consuming method of DMSPE-ultra-high performance liquid chromatography-tandem mass spectrometry (DMSPE-UHPLC-MS/MS) was successfully applied to the pre-concentration and determination of twelve SAs in milk samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Simultaneous determination of sibutramine and its active metabolites in human plasma by LC-MS/MS and its application to a pharmacokinetic study.

PubMed

Bae, Jung-Woo; Choi, Chang-Ik; Jang, Choon-Gon; Lee, Seok-Yong

2011-11-01

A simple and sensitive liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) technique was developed and validated for the determination of sibutramine and its N-desmethyl metabolites (M1 and M2) in human plasma. After extraction with methyl t-butyl ether, chromatographic separation of analytes in human plasma was performed using a reverse-phase Luna C18 column with a mobile phase of acetonitrile-10 mm ammonium formate buffer (50:50, v/v) and quantified by ESI-MS/MS detection in positive ion mode. The flow rate of the mobile phase was 200 μL/min and the retention times of sibutramine, M1, M2 and internal standard (chlorpheniramine) were 1.5, 1.4, 1.3 and 0.9 min, respectively. The calibration curves were linear over the range 0.05-20 ng/mL, for sibutramine, M1 and M2. The lower limit of quantification was 0.05 ng/mL using 500 μL of human plasma. The mean accuracy and the precision in the intra- and inter-day validation for sibutramine, M1 and M2 were acceptable. This LC-MS/MS method showed improved sensitivity and a short run time for the quantification of sibutramine and its two active metabolites in plasma. The validated method was successfully applied to a pharmacokinetic study in human. Copyright © 2011 John Wiley & Sons, Ltd.

Determination of cytokinins in coconut (Cocos nucifera L.) water using capillary zone electrophoresis-tandem mass spectrometry.

PubMed

Ge, Liya; Yong, Jean Wan Hong; Tan, Swee Ngin; Ong, Eng Shi

2006-06-01

The applicability of CZE in combination with MS and MS/MS methods for the simultaneous separation and determination of 12 cytokinins was investigated for the first time. Cytokinins were first completely separated by CZE within less than 20 min using a volatile buffer and then detected directly by MS or MS/MS. Satisfactory separation of the 12 cytokinin standards was achieved using a 25 mM ammonium formate/formic acid buffer (pH 3.4) and 3% ACN v/v with a separation voltage of 25 kV. On the basis of the resolution of the neighboring peaks, the various parameters for CZE-MS optimization, such as buffer pH value, concentration of buffer and organic modifier, applied voltage and sheath liquid, were evaluated systematically. MS/MS with multiple reaction monitoring detection was carried out to obtain sufficient selectivity and sensitivity. The combination of on-line sample stacking and CZE-MS/MS achieved a detection limit in the range of 0.05-0.18 microM for the 12 cytokinins at an S/N of 3. The optimized CZE-MS/MS method was simple, rapid, low cost, robust and highly selective. Furthermore, the developed method was successfully applied to screen for endogenous cytokinins in purified coconut water extract sample. Nine cytokinins were detected and quantified in coconut water after SPE.

Rapid and Simultaneous Analysis of 360 Pesticides in Brown Rice, Spinach, Orange, and Potato Using Microbore GC-MS/MS.

PubMed

Lee, Jonghwa; Kim, Leesun; Shin, Yongho; Lee, Junghak; Lee, Jiho; Kim, Eunhye; Moon, Joon-Kwan; Kim, Jeong-Han

2017-04-26

A multiresidue method for the simultaneous and rapid analysis of 360 pesticides in representative agricultural produce (brown rice, orange, spinach, and potato) was developed using a modified QuEChERS procedure combined with gas chromatography-tandem mass spectrometry (GC-MS/MS). Selected reaction monitoring transition parameters (e.g., collision energy, precursor and product ions) in MS/MS were optimized to achieve the best selectivity and sensitivity for a wide range of GC-amenable pesticides. A short (20 m) microbore (0.18 mm i.d.) column resulted in better signal-to-noise ratio with reduced analysis time than a conventional narrowbore column (30 m × 0.25 mm i.d.). The priming injection dramatically increased peak areas by masking effect on a new GC liner. The limit of quantitation was <0.01 mg/kg, and the correlation coefficients (r 2 ) of matrix-matched standards were >0.99 within the range of 0.0025-0.1 mg/kg. Acetonitrile with 0.1% formic acid without additional buffer salts was used for pesticide extraction, whereas only primary-secondary amine (PSA) was used for dispersive solid phase extraction (dSPE) cleanup, to achieve good recoveries for most of the target analytes. The recoveries ranged from 70 to 120% with relative standard deviations of ≤20% at 0.01 and 0.05 mg/kg spiking levels (n = 6) in all samples, indicating acceptable accuracy and precision of the method. Seventeen real samples from local markets were analyzed by using the optimized method, and 14 pesticides in 11 incurred samples were found at below the maximum residue limits.

Implementation of laser induced fluorescence in a pulse radiolysis experiment--a new way to analyze resazurin-like reduction mechanisms.

PubMed

Balcerzyk, A; Baldacchino, G

2014-04-07

Resazurin (RNO) reduction by hydrated electrons produces a fluorescent molecule: resorufin (RN). To take advantage of RN fluorescence, a novel setup is designed by implementing fluorescence detection induced by laser in a pulse radiolysis experiment. Time resolved fluorescence spectra were recorded with a fast gated intensified CCD camera during the reduction of RNO from μs to ms. Two 532 nm laser types have been used to describe the short μs range by a 5 ns Q-switch laser and the μs-ms range by a CW DPSS laser. By fitting the simulated model to the experimental data a second order rate constant of 10(9) M(-1) s(-1) was re-evaluated. This method should be considered in the near future in many in situ and real time measurements for evaluating radical production.

Identification and characterization by LC-UV-MS/MS of melanotan II skin-tanning products sold illegally on the Internet.

PubMed

Breindahl, Torben; Evans-Brown, Michael; Hindersson, Peter; McVeigh, Jim; Bellis, Mark; Stensballe, Allan; Kimergård, Andreas

2015-02-01

New methods were developed and validated to determine the identity, contents, and purity of samples of melanotan II, a synthetic melanocortin receptor agonist, sold in vials as injectable skin-tanning products that were purchased from three online shops. Methods were based on liquid chromatography with ultra-violet detection (LC-UV) at wavelength 218 nm, and tandem mass spectrometric detection (MS/MS) after collision-induced fragmentation of the double charged [M+2H](2+) precursor ion (m/z 513). Identification of melanotan II was verified by correct chromatographic retention time, and relative abundance ratios of five qualifying fragment ions. LC-UV was used to quantify melanotan II as well as impurities. Method validation was performed with reference to guidelines for assessing active substances in authorized medicinal products to reach acceptable accuracy and precision. Vials from two shops contained unknown impurities ranging from 4.1 to 5.9%; impurities from one shop were below the quantification limit. The total amount of melanotan II in vials ranged between 4.32 and 8.84 mg, although each shop claimed that vials contained 10 mg melanotan II. A broad range of drugs used for enhancement purposes can be obtained from the illicit market. However, users of these drugs may be exposed to a range of potential harms, as shown in this study, given that these products are manufactured, distributed and supplied from an illicit market. Copyright © 2014 John Wiley & Sons, Ltd.

Use of specific peptide biomarkers for quantitative confirmation of hidden allergenic peanut proteins Ara h 2 and Ara h 3/4 for food control by liquid chromatography-tandem mass spectrometry.

PubMed

Careri, M; Costa, A; Elviri, L; Lagos, J-B; Mangia, A; Terenghi, M; Cereti, A; Garoffo, L Perono

2007-11-01

A liquid chromatography-electrospray-tandem mass spectrometry (LC-ESI-MS-MS) method based on the detection of biomarker peptides from allergenic proteins was devised for confirming and quantifying peanut allergens in foods. Peptides obtained from tryptic digestion of Ara h 2 and Ara h 3/4 proteins were identified and characterized by LC-MS and LC-MS-MS with a quadrupole-time of flight mass analyzer. Four peptides were chosen and investigated as biomarkers taking into account their selectivity, the absence of missed cleavages, the uniform distribution in the Ara h 2 and Ara h 3/4 protein isoforms together with their spectral features under ESI-MS-MS conditions, and good repeatability of LC retention time. Because of the different expression levels, the selection of two different allergenic proteins was proved to be useful in the identification and univocal confirmation of the presence of peanuts in foodstuffs. Using rice crisp and chocolate-based snacks as model food matrix, an LC-MS-MS method with triple quadrupole mass analyzer allowed good detection limits to be obtained for Ara h 2 (5 microg protein g(-1) matrix) and Ara h 3/4 (1 microg protein g(-1) matrix). Linearity of the method was established in the 10-200 microg g(-1) range of peanut proteins in the food matrix investigated. Method selectivity was demonstrated by analyzing tree nuts (almonds, pecan nuts, hazelnuts, walnuts) and food ingredients such as milk, soy beans, chocolate, cornflakes, and rice crisp.

A novel molecular microbiologic technique for the rapid diagnosis of microbial invasion of the amniotic cavity and intra-amniotic infection in preterm labor with intact membranes.

PubMed

Romero, Roberto; Miranda, Jezid; Chaiworapongsa, Tinnakorn; Chaemsaithong, Piya; Gotsch, Francesca; Dong, Zhong; Ahmed, Ahmed I; Yoon, Bo Hyun; Hassan, Sonia S; Kim, Chong Jai; Korzeniewski, Steven J; Yeo, Lami

2014-04-01

The diagnosis of microbial invasion of the amniotic cavity (MIAC) has been traditionally performed using traditional cultivation techniques, which require growth of microorganisms in the laboratory. Shortcomings of culture methods include the time required (days) for identification of microorganisms, and that many microbes involved in the genesis of human diseases are difficult to culture. A novel technique combines broad-range real-time polymerase chain reaction with electrospray ionization time-of-flight mass spectrometry (PCR/ESI-MS) to identify and quantify genomic material from bacteria and viruses. AF samples obtained by transabdominal amniocentesis from 142 women with preterm labor and intact membranes (PTL) were analyzed using cultivation techniques (aerobic, anaerobic, and genital mycoplasmas) as well as PCR/ESI-MS. The prevalence and relative magnitude of intra-amniotic inflammation [AF interleukin 6 (IL-6) concentration ≥ 2.6 ng/mL], acute histologic chorioamnionitis, spontaneous preterm delivery, and perinatal mortality were examined. (i) The prevalence of MIAC in patients with PTL was 7% using standard cultivation techniques and 12% using PCR/ESI-MS; (ii) seven of ten patients with positive AF culture also had positive PCR/ESI-MS [≥17 genome equivalents per PCR reaction well (GE/well)]; (iii) patients with positive PCR/ESI-MS (≥17 GE/well) and negative AF cultures had significantly higher rates of intra-amniotic inflammation and acute histologic chorioamnionitis, a shorter interval to delivery [median (interquartile range-IQR)], and offspring at higher risk of perinatal mortality, than women with both tests negative [90% (9/10) versus 32% (39/122) OR: 5.6; 95% CI: 1.4-22; (P < 0.001); 70% (7/10) versus 35% (39/112); (P = 0.04); 1 (IQR: <1-2) days versus 25 (IQR: 5-51) days; (P = 0.002), respectively]; (iv) there were no significant differences in these outcomes between patients with positive PCR/ESI-MS (≥17 GE/well) who had negative AF cultures and those with positive AF cultures; and (v) PCR/ESI-MS detected genomic material from viruses in two patients (1.4%). (i) Rapid diagnosis of intra-amniotic infection is possible using PCR/ESI-MS; (ii) the combined use of biomarkers of inflammation and PCR/ESI-MS allows for the identification of specific bacteria and viruses in women with preterm labor and intra-amniotic infection; and (iii) this approach may allow for administration of timely and specific interventions to reduce morbidity attributed to infection-induced preterm birth. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.

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

NASA Astrophysics Data System (ADS)

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

2012-09-01

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 α-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.

Microextraction with polyethersulfone for bisphenol-A, alkylphenols and hormones determination in water samples by means of gas chromatography-mass spectrometry and liquid chromatography-tandem mass spectrometry analysis.

PubMed

Ros, O; Vallejo, A; Blanco-Zubiaguirre, L; Olivares, M; Delgado, A; Etxebarria, N; Prieto, A

2015-03-01

In the present work, the suitability of polyethersulfone (PES) tube was assessed for the simultaneous sorptive microextraction of commonly found endocrine disrupting compounds in natural waters such as bisphenol-A (BPA), nonylphenol technical mixture (NP mix), 4-tert-octylphenol (4tOP), 4-n-octylphenol (4-nOP), 17β-estradiol (E2) and 17α-ethynilestradiol (EE2). After the concentration of target compounds in the PES polymer, the analytes were recovered soaking the polymer with a suitable solvent (ethyl acetate or methanol), derivatized using N,O-bis(trimethylsilyl)trifluoroacetamide with 1% of trimethylchlorosilane (BSTFA+1% TMCS) and determined by gas chromatography-mass spectrometry (GC-MS). The analysis was also performed without derivatization step by means of liquid chromatography-tandem mass spectrometry (LC-MS/MS). Extraction parameters (addition of MeOH, ionic strength, extraction speed and time and desorption time) were evaluated and the optimum conditions were fixed as follows: 150 mL water samples containing a 10% (w/v) of sodium chloride and using 5 tubular PES sorbent fibers (1.5 cm length×0.7 mm o.d.). Equilibrium conditions were achieved after 9 h, with absolute extraction efficiencies ranging from 27 to 56%. On the whole, good apparent recoveries were achieved (68-103% and 81-122% for GC-MS and LC-MS/MS, respectively) using deuterated analogues as surrogates. Achieved quantification limits (LOQs) varied between 2-154 ng/L and 2-63 ng/L for all the compounds using GC-MS and LC-MS/MS, respectively. The effect of organic matter was evaluated previous to apply the final method to the analysis of estuarine and wastewater real samples. The comparison of both methods showed that overall, PES-LC-MS/MS provided shorter sample preparation time and better LODs, but PES-silylation-GC-MS allowed the simultaneous determination of all the studied compounds with adequate repeatability and accuracy. Copyright © 2014 Elsevier B.V. All rights reserved.

Total Laboratory Automation and Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry Improve Turnaround Times in the Clinical Microbiology Laboratory: a Retrospective Analysis.

PubMed

Theparee, Talent; Das, Sanchita; Thomson, Richard B

2018-01-01

Technological advances have changed the practice of clinical microbiology. We implemented Bruker matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) and BD Kiestra total laboratory automation (TLA) 4 and 3 years ago, respectively. To assess the impact of these new technologies, we compared turnaround times (TATs) for positive and negative urine cultures before and after implementation. In comparison I, TATs for 61,157 urine cultures were extracted for two periods corresponding to pre-TLA and post-TLA, both using MALDI-TOF MS for organism identification. In comparison II, time to organism identification (ID) and antimicrobial susceptibility (AST) reports were calculated for 5,402 positive culture reports representing four different periods: (i) manual plating and conventional biochemical identification (CONV), (ii) manual plating and MALDI-TOF MS identification (MALDI), (iii) MALDI-TOF MS identification and early phase implementation of TLA (TLA1), and (iv) MALDI-TOF MS identification and late phase implementation of TLA (TLA2). By the comparison I results, median pre- and post-TLA TATs to organism IDs (18.5 to 16.9 h), AST results (41.8 to 40.8 h), and preliminary results for negative cultures (17.7 to 13.6 h), including interquartile ranges for all comparisons, were significantly decreased post-TLA ( P < 0.001). By the comparison II results, MALDI significantly improved TAT to organism ID compared to CONV (21.3 to 18 h). TLA further improved overall TAT to ID (18 to 16.5 h) and AST (42.3 to 40.7 h) results compared to MALDI ( P < 0.001). In summary, TLA significantly improved TAT to organism ID, AST report, and preliminary negative results. MALDI-TOF MS significantly improved TAT for organism ID. Use of MALDI-TOF MS and TLA individually and together results in significant decreases in microbiology report TATs. Copyright © 2017 Theparee et al.

Total Laboratory Automation and Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry Improve Turnaround Times in the Clinical Microbiology Laboratory: a Retrospective Analysis

PubMed Central

Theparee, Talent; Das, Sanchita

2017-01-01

ABSTRACT Technological advances have changed the practice of clinical microbiology. We implemented Bruker matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) and BD Kiestra total laboratory automation (TLA) 4 and 3 years ago, respectively. To assess the impact of these new technologies, we compared turnaround times (TATs) for positive and negative urine cultures before and after implementation. In comparison I, TATs for 61,157 urine cultures were extracted for two periods corresponding to pre-TLA and post-TLA, both using MALDI-TOF MS for organism identification. In comparison II, time to organism identification (ID) and antimicrobial susceptibility (AST) reports were calculated for 5,402 positive culture reports representing four different periods: (i) manual plating and conventional biochemical identification (CONV), (ii) manual plating and MALDI-TOF MS identification (MALDI), (iii) MALDI-TOF MS identification and early phase implementation of TLA (TLA1), and (iv) MALDI-TOF MS identification and late phase implementation of TLA (TLA2). By the comparison I results, median pre- and post-TLA TATs to organism IDs (18.5 to 16.9 h), AST results (41.8 to 40.8 h), and preliminary results for negative cultures (17.7 to 13.6 h), including interquartile ranges for all comparisons, were significantly decreased post-TLA (P < 0.001). By the comparison II results, MALDI significantly improved TAT to organism ID compared to CONV (21.3 to 18 h). TLA further improved overall TAT to ID (18 to 16.5 h) and AST (42.3 to 40.7 h) results compared to MALDI (P < 0.001). In summary, TLA significantly improved TAT to organism ID, AST report, and preliminary negative results. MALDI-TOF MS significantly improved TAT for organism ID. Use of MALDI-TOF MS and TLA individually and together results in significant decreases in microbiology report TATs. PMID:29118171

Development and validation of a fast and simple multi-analyte procedure for quantification of 40 drugs relevant to emergency toxicology using GC-MS and one-point calibration.

PubMed

Meyer, Golo M J; Weber, Armin A; Maurer, Hans H

2014-05-01

Diagnosis and prognosis of poisonings should be confirmed by comprehensive screening and reliable quantification of xenobiotics, for example by gas chromatography-mass spectrometry (GC-MS) or liquid chromatography-mass spectrometry (LC-MS). The turnaround time should be short enough to have an impact on clinical decisions. In emergency toxicology, quantification using full-scan acquisition is preferable because this allows screening and quantification of expected and unexpected drugs in one run. Therefore, a multi-analyte full-scan GC-MS approach was developed and validated with liquid-liquid extraction and one-point calibration for quantification of 40 drugs relevant to emergency toxicology. Validation showed that 36 drugs could be determined quickly, accurately, and reliably in the range of upper therapeutic to toxic concentrations. Daily one-point calibration with calibrators stored for up to four weeks reduced workload and turn-around time to less than 1 h. In summary, the multi-analyte approach with simple liquid-liquid extraction, GC-MS identification, and quantification over fast one-point calibration could successfully be applied to proficiency tests and real case samples. Copyright © 2013 John Wiley & Sons, Ltd.

Discrimination of Aspergillus isolates at the species and strain level by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry fingerprinting.

PubMed

Hettick, Justin M; Green, Brett J; Buskirk, Amanda D; Kashon, Michael L; Slaven, James E; Janotka, Erika; Blachere, Francoise M; Schmechel, Detlef; Beezhold, Donald H

2008-09-15

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) was used to generate highly reproducible mass spectral fingerprints for 12 species of fungi of the genus Aspergillus and 5 different strains of Aspergillus flavus. Prior to MALDI-TOF MS analysis, the fungi were subjected to three 1-min bead beating cycles in an acetonitrile/trifluoroacetic acid solvent. The mass spectra contain abundant peaks in the range of 5 to 20kDa and may be used to discriminate between species unambiguously. A discriminant analysis using all peaks from the MALDI-TOF MS data yielded error rates for classification of 0 and 18.75% for resubstitution and cross-validation methods, respectively. If a subset of 28 significant peaks is chosen, resubstitution and cross-validation error rates are 0%. Discriminant analysis of the MALDI-TOF MS data for 5 strains of A. flavus using all peaks yielded error rates for classification of 0 and 5% for resubstitution and cross-validation methods, respectively. These data indicate that MALDI-TOF MS data may be used for unambiguous identification of members of the genus Aspergillus at both the species and strain levels.

Electro-thermal vaporization direct analysis in real time-mass spectrometry for water contaminant analysis during space missions.

PubMed

Dwivedi, Prabha; Gazda, Daniel B; Keelor, Joel D; Limero, Thomas F; Wallace, William T; Macatangay, Ariel V; Fernández, Facundo M

2013-10-15

The development of a direct analysis in real time-mass spectrometry (DART-MS) method and first prototype vaporizer for the detection of low molecular weight (∼30-100 Da) contaminants representative of those detected in water samples from the International Space Station is reported. A temperature-programmable, electro-thermal vaporizer (ETV) was designed, constructed, and evaluated as a sampling interface for DART-MS. The ETV facilitates analysis of water samples with minimum user intervention while maximizing analytical sensitivity and sample throughput. The integrated DART-ETV-MS methodology was evaluated in both positive and negative ion modes to (1) determine experimental conditions suitable for coupling DART with ETV as a sample inlet and ionization platform for time-of-flight MS, (2) to identify analyte response ions, (3) to determine the detection limit and dynamic range for target analyte measurement, and (4) to determine the reproducibility of measurements made with the method when using manual sample introduction into the vaporizer. Nitrogen was used as the DART working gas, and the target analytes chosen for the study were ethyl acetate, acetone, acetaldehyde, ethanol, ethylene glycol, dimethylsilanediol, formaldehyde, isopropanol, methanol, methylethyl ketone, methylsulfone, propylene glycol, and trimethylsilanol.

Rapid Characterization of Microalgae and Microalgae Mixtures Using Matrix-Assisted Laser Desorption Ionization Time-Of-Flight Mass Spectrometry (MALDI-TOF MS)

PubMed Central

Barbano, Duane; Diaz, Regina; Zhang, Lin; Sandrin, Todd; Gerken, Henri; Dempster, Thomas

2015-01-01

Current molecular methods to characterize microalgae are time-intensive and expensive. Matrix Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) may represent a rapid and economical alternative approach. The objectives of this study were to determine whether MALDI-TOF MS can be used to: 1) differentiate microalgae at the species and strain levels and 2) characterize simple microalgal mixtures. A common protein extraction sample preparation method was used to facilitate rapid mass spectrometry-based analysis of 31 microalgae. Each yielded spectra containing between 6 and 56 peaks in the m/z 2,000 to 20,000 range. The taxonomic resolution of this approach appeared higher than that of 18S rDNA sequence analysis. For example, two strains of Scenedesmus acutus differed only by two 18S rDNA nucleotides, but yielded distinct MALDI-TOF mass spectra. Mixtures of two and three microalgae yielded relatively complex spectra that contained peaks associated with members of each mixture. Interestingly, though, mixture-specific peaks were observed at m/z 11,048 and 11,230. Our results suggest that MALDI-TOF MS affords rapid characterization of individual microalgae and simple microalgal mixtures. PMID:26271045

Posterior Cricoarytenoid Muscle Dynamics in Canines and Humans

PubMed Central

Chhetri, Dinesh K.; Neubauer, Juergen; Sofer, Elazar

2015-01-01

Objective The posterior cricoarytenoid (PCA) muscle is the sole abductor of the glottis and serves important functions during respiration, phonation, cough, and sniff. The present study examines vocal fold abduction dynamics during PCA muscle activation. Study Design Basic science study using an in vivo canine model and human subjects. Methods In four canines and five healthy humans vocal fold abduction time was measured using high speed video recording. In the canines, PCA muscle activation was achieved using graded stimulation of the PCA nerve branch. The human subjects performed coughing and sniffing tasks. High speed video and audio signals were concurrently recorded. Results In the canines the vocal fold moved posteriorly, laterally, and superiorly during abduction. Average time to reach 10%, 50% and 90% abduction was 23, 50, and 100 ms with low stimulation, 24, 58, and 129 ms with medium stimulation, and 21, 49, and 117 ms with high level stimulation. In the humans, 100% abduction times for coughing and sniffing tasks were 79 and 193 ms, respectively. Conclusion The PCA abduction times in canines are within the range in humans. The results also further support the notion that PCA muscles are fully active during cough. Level of Evidence N/A (Animal studies and basic research) PMID:24781959

Subsurface Supergranular Vertical Flows as Measured Using Large Distance Separations in Time-Distance Helioseismology

NASA Technical Reports Server (NTRS)

Duvall, T. L., Jr.; Hanasoge, S. M.

2012-01-01

As large-distance rays (say, 10-24 deg) approach the solar surface approximately vertically, travel times measured from surface pairs for these large separations are mostly sensitive to vertical flows, at least for shallow flows within a few Mm of the solar surface. All previous analyses of supergranulation have used smaller separations and have been hampered by the difficulty of separating the horizontal and vertical flow components. We find that the large separation travel times associated with upergranulation cannot be studied using the standard phase-speed filters of time-distance helioseismology. These filters, whose use is based upon a refractive model of the perturbations,reduce the resultant travel time signal by at least an order of magnitude at some distances. More effective filters are derived. Modeling suggests that the center-annulus travel time difference in the separation range 10-24 deg is insensitive to the horizontally diverging flow from the centers of the supergranules and should lead to a constant signal from the vertical flow. Our measurement of this quantity for the average supergranule, 5.1 s, is constant over the distance range. This magnitude of signal cannot be caused by the level of upflow at cell centers seen at the photosphere of 10 m/s extended in depth. It requires the vertical flow to increase with depth. A simple Gaussian model of the increase with depth implies a peak upward flow of 240 m/s at a depth of 2.3 Mm and a peak horizontal flow of 700 m/s at a depth of 1.6 Mm.

Multi-exposure speckle imaging of cerebral blood flow: a pilot clinical study (Conference Presentation)

NASA Astrophysics Data System (ADS)

Richards, Lisa M.; Kazmi, S. M. S.; Olin, Katherine E.; Waldron, James S.; Fox, Douglas J.; Dunn, Andrew K.

2017-03-01

Monitoring cerebral blood flow (CBF) during neurosurgery is essential for detecting ischemia in a timely manner for a wide range of procedures. Multiple clinical studies have demonstrated that laser speckle contrast imaging (LSCI) has high potential to be a valuable, label-free CBF monitoring technique during neurosurgery. LSCI is an optical imaging method that provides blood flow maps with high spatiotemporal resolution requiring only a coherent light source, a lens system, and a camera. However, the quantitative accuracy and sensitivity of LSCI is limited and highly dependent on the exposure time. An extension to LSCI called multi-exposure speckle imaging (MESI) overcomes these limitations, and was evaluated intraoperatively in patients undergoing brain tumor resection. This clinical study (n = 7) recorded multiple exposure times from the same cortical tissue area, and demonstrates that shorter exposure times (≤1 ms) provide the highest dynamic range and sensitivity for sampling flow rates in human neurovasculature. This study also combined exposure times using the MESI model, demonstrating high correlation with proper image calibration and acquisition. The physiological accuracy of speckle-estimated flow was validated using conservation of flow analysis on vascular bifurcations. Flow estimates were highly conserved in MESI and 1 ms exposure LSCI, with percent errors at 6.4% ± 5.3% and 7.2% ± 7.2%, respectively, while 5 ms exposure LSCI had higher errors at 21% ± 10% (n = 14 bifurcations). Results from this study demonstrate the importance of exposure time selection for LSCI, and that intraoperative MESI can be performed with high quantitative accuracy.

Nonlinear Analysis of Surface EMG Time Series of Back Muscles

NASA Astrophysics Data System (ADS)

Dolton, Donald C.; Zurcher, Ulrich; Kaufman, Miron; Sung, Paul

2004-10-01

A nonlinear analysis of surface electromyography time series of subjects with and without low back pain is presented. The mean-square displacement and entropy shows anomalous diffusive behavior on intermediate time range 10 ms < t < 1 s. This behavior implies the presence of correlations in the signal. We discuss the shape of the power spectrum of the signal.

Time course of word production in fast and slow speakers: a high density ERP topographic study.

PubMed

Laganaro, Marina; Valente, Andrea; Perret, Cyril

2012-02-15

The transformation of an abstract concept into an articulated word is achieved through a series of encoding processes, which time course has been repeatedly investigated in the psycholinguistic and neuroimaging literature on single word production. The estimates of the time course issued from previous investigations represent the timing of process duration for mean processing speed: as production speed varies significantly across speakers, a crucial question is how the timing of encoding processing varies with speed. Here we investigated whether between-subjects variability in the speed of speech production is distributed along all encoding processes or if it is accounted for by a specific processing stage. We analysed event-related electroencephalographical (ERP) correlates during overt picture naming in 45 subjects divided into three speed subgroups according to their production latencies. Production speed modulated waveform amplitudes in the time window ranging from about 200 to 350 ms after picture presentation and the duration of a stable electrophysiological spatial configuration in the same time period. The remaining time windows from picture onset to 200 ms before articulation were unaffected by speed. By contrast, the manipulation of a psycholinguistic variable, word age-of-acquisition, modulated ERPs in all speed subgroups in a different and later time period, starting at around 400 ms after picture presentation, associated with phonological encoding processes. These results indicate that the between-subject variability in the speed of single word production is principally accounted for by the timing of a stable electrophysiological activity in the 200-350 ms time period, presumably associated with lexical selection. Copyright © 2011 Elsevier Inc. All rights reserved.

Analysis and Quantitation of Glycated Hemoglobin by Matrix Assisted Laser Desorption/Ionization Time of Flight Mass Spectrometry

NASA Astrophysics Data System (ADS)

Hattan, Stephen J.; Parker, Kenneth C.; Vestal, Marvin L.; Yang, Jane Y.; Herold, David A.; Duncan, Mark W.

2016-03-01

Measurement of glycated hemoglobin is widely used for the diagnosis and monitoring of diabetes mellitus. Matrix assisted laser desorption/ionization (MALDI) time of flight (TOF) mass spectrometry (MS) analysis of patient samples is used to demonstrate a method for quantitation of total glycation on the β-subunit of hemoglobin. The approach is accurate and calibrated with commercially available reference materials. Measurements were linear (R2 > 0.99) across the clinically relevant range of 4% to 20% glycation with coefficients of variation of ≤ 2.5%. Additional and independent measurements of glycation of the α-subunit of hemoglobin are used to validate β-subunit glycation measurements and distinguish hemoglobin variants. Results obtained by MALDI-TOF MS were compared with those obtained in a clinical laboratory using validated HPLC methodology. MALDI-TOF MS sample preparation was minimal and analysis times were rapid making the method an attractive alternative to methodologies currently in practice.

Electrospray of 1-Butyl-3-Methylimidazolium Dicyanamide Under Variable Flow Rate Operations

DTIC Science & Technology

2014-06-27

cm length. The capillary needle is stainless steel with a tapered tip of 50 μm inner diameter and 3.5 cm length. Both capillaries are commercially...connected. Figure 8 shows the emission current results of a 50 μm stainless - steel tip over the same IL flow rate range as Fig. 5. The emitter... fuming nitric acid, resulting in an ignition delay time of 47 ms, longer than the desired maximumof 5ms.Numerical predictions byBerg andRovey [18,19

Qualitative analysis of seized cocaine samples using desorption electrospray ionization- mass spectrometry (DESI-MS).

PubMed

Stojanovska, Natasha; Tahtouh, Mark; Kelly, Tamsin; Beavis, Alison; Fu, Shanlin

2015-05-01

Desorption electrospray ionization - mass spectrometry (DESI-MS) is a useful technique for the qualitative analysis of compounds found in seized drug material. In this study, DESI-MS was utilized in the screening analysis of illicit cocaine samples. The technique was also applied to the geographical origin determination of these samples. The limit of detection was determined to be 24.3 µg (or 3.47 µg/mm(2) ) and the analysis time was less than 1 minute per sample. The intra-day and inter-day precision for the detection of cocaine was 11 % and 42 %, respectively; therefore the quantitative data provided by DESI-MS was limited in its use for accurate determination of cocaine concentration in a sample. Using the quadrupole time-of-flight (QTOF) mass spectrometer, the presence of cocaine and impurities detected were confirmed by accurate tandem MS data. The qualitative chemical profiles obtained using DESI-MS were compared to two popular analysis techniques, GC-MS and LC-MS. The effects of a range of adulterants including caffeine, procaine, levamisole, lignocaine, paracetamol, and atropine on the detectability of cocaine were also investigated. It was found that the addition of these adulterants in a cocaine sample did not prevent the detection of the analyte itself (there was slight enhancement in some samples), which was useful in drug detection. The detection of truxillines in the seized samples by DESI-MS aided in the preliminary determination of geographical origin, i.e., Bolivian, Peruvian or Colombian leaf origin. The application of DESI-MS to the qualitative analysis and screening of seized cocaine samples demonstrates the potential and applicability of the technique to the fast chemical profiling of illicit samples. Copyright © 2014 John Wiley & Sons, Ltd.

Measurement of citrate in urine using liquid chromatography tandem mass spectrometry: comparison with an enzymatic method.

PubMed

Keevil, B G; Owen, L; Thornton, S; Kavanagh, J

2005-09-01

Measurement of urine citrate is used to assess the risk of further urinary stone formation and to assess the benefit of treatment in affected individuals. We wanted to develop a simple and rapid liquid chromatography tandem mass spectrometry (LC-MS/MS) method for the analysis of urinary citrate and to compare it with our current enzymatic assay. For the LC-MS/MS assay, samples were prepared in a deep-well block by adding 10 microL of urine and 20 microL of internal standard to 400 microL of water. After mixing, 3 microL of the diluted sample was injected into the LC-MS/MS system. An LC system was used to isocratically elute a C18 column (50 x 2.1 mm) with 0.4 mL/min water containing 2 mmol/L ammonium acetate and 0.1% (v/v) formic acid. A step gradient of 100% methanol containing 2 mmol/L ammonium acetate and 0.1% (v/v) formic acid was used to wash the column. The retention times were 1.4 min for citrate and 1.4 min for d4-citrate. Cycle time was 4.0 min, injection to injection. The analytes were monitored using a tandem mass spectrometer operated in multiple reaction monitoring mode using the following transitions, citrate m/z 191.0>111.0 and d4-citrate m/z 195.0>113.0. Within and between-batch coefficients of variation were <3% over the range 480-3800 micromol/L. The lower limit of quantification was 24.0 micromol/L. Regression analysis showed LC-MS/MS = 0.8781 (enzymatic assay) + 102.5, r = 0.964, n = 73. We have developed a simple LC-MS/MS method for urinary citrate measurement that shows acceptable performance.

Subsurface Supergranular Vertical Flows as Measured Using Large Distance Separations in Time-Distance Helioseismology

NASA Technical Reports Server (NTRS)

Duvall, Thomas L., Jr.; Hanasoge, S. M.

2012-01-01

As large-distance rays (say, 10 - 24deg) approach the solar surface approximately vertically, travel times measured from surface pairs for these large separations are mostly sensitive to vertical flows, at least for shallow flows within a few Mm of the solar surface. All previous analyses of supergranulation have used smaller separations and have been hampered by the difficulty of separating the horizontal and vertical flow components. We find that the large-separation travel times associated with supergranulation cannot be studied using the standard phase-speed filters of time-distance helioseismology. These filters, whose use is based upon a refractive model of the perturbations, reduce the resultant travel time signal by at least an order of magnitude at some distances. More effective filters are derived. Modeling suggests that the center-annulus travel-time difference [outward-going time minus inward-going time] in the separation range delta= 10 - 24deg is insensitive to the horizontally diverging flow from the centers of the supergranules and should lead to a constant signal from the vertical flow. Our measurement of this quantity, 5.1+/-0.1 seconds, is constant over the distance range. This magnitude of the signal cannot be caused by the level of upflow at cell centers seen at the photosphere of 10 ms(exp-1) extended in depth. It requires the vertical flow to increase with depth. A simple Gaussian model of the increase with depth implies a peak upward flow of 240 ms(exp-1) at a depth of 2.3 Mm and a peak horizontal flow of 700 ms(exp-1) at a depth of 1.6 Mm.

LORETA EEG phase reset of the default mode network.

PubMed

Thatcher, Robert W; North, Duane M; Biver, Carl J

2014-01-01

The purpose of this study was to explore phase reset of 3-dimensional current sources in Brodmann areas located in the human default mode network (DMN) using Low Resolution Electromagnetic Tomography (LORETA) of the human electroencephalogram (EEG). The EEG was recorded from 19 scalp locations from 70 healthy normal subjects ranging in age from 13 to 20 years. A time point by time point computation of LORETA current sources were computed for 14 Brodmann areas comprising the DMN in the delta frequency band. The Hilbert transform of the LORETA time series was used to compute the instantaneous phase differences between all pairs of Brodmann areas. Phase shift and lock durations were calculated based on the 1st and 2nd derivatives of the time series of phase differences. Phase shift duration exhibited three discrete modes at approximately: (1) 25 ms, (2) 50 ms, and (3) 65 ms. Phase lock duration present primarily at: (1) 300-350 ms and (2) 350-450 ms. Phase shift and lock durations were inversely related and exhibited an exponential change with distance between Brodmann areas. The results are explained by local neural packing density of network hubs and an exponential decrease in connections with distance from a hub. The results are consistent with a discrete temporal model of brain function where anatomical hubs behave like a "shutter" that opens and closes at specific durations as nodes of a network giving rise to temporarily phase locked clusters of neurons for specific durations.

Cortical activity patterns predict speech discrimination ability

PubMed Central

Engineer, Crystal T; Perez, Claudia A; Chen, YeTing H; Carraway, Ryan S; Reed, Amanda C; Shetake, Jai A; Jakkamsetti, Vikram; Chang, Kevin Q; Kilgard, Michael P

2010-01-01

Neural activity in the cerebral cortex can explain many aspects of sensory perception. Extensive psychophysical and neurophysiological studies of visual motion and vibrotactile processing show that the firing rate of cortical neurons averaged across 50–500 ms is well correlated with discrimination ability. In this study, we tested the hypothesis that primary auditory cortex (A1) neurons use temporal precision on the order of 1–10 ms to represent speech sounds shifted into the rat hearing range. Neural discrimination was highly correlated with behavioral performance on 11 consonant-discrimination tasks when spike timing was preserved and was not correlated when spike timing was eliminated. This result suggests that spike timing contributes to the auditory cortex representation of consonant sounds. PMID:18425123

Magnetic sporopollenin-cyanopropyltriethoxysilane-dispersive micro-solid phase extraction coupled with high performance liquid chromatography for the determination of selected non-steroidal anti-inflammatory drugs in water samples.

PubMed

Abd Wahib, Siti Munirah; Wan Ibrahim, Wan Aini; Sanagi, Mohd Marsin; Kamboh, Muhammad Afzal; Abdul Keyon, Aemi S

2018-01-12

A facile dispersive-micro-solid phase extraction (D-μ-SPE) method coupled with HPLC for the analysis of selected non-steroidal anti-inflammatory drugs (NSAIDs) in water samples was developed using a newly prepared magnetic sporopollenin-cyanopropyltriethoxysilane (MS-CNPrTEOS) sorbent. Sporopollenin homogenous microparticles of Lycopodium clavatum spores possessed accessible functional groups that facilitated surface modification. Simple modification was performed by functionalization with 3-cyanopropyltriethoxysilane (CNPrTEOS) and magnetite was introduced onto the biopolymer to simplify the extraction process. MS-CNPrTEOS was identified by infrared spectrometrywhile the morphology and the magnetic property were confirmed by scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM), respectively. To maximize the extraction performance of ketoprofen, ibuprofen, diclofenac and mefenamic acid using the proposed MS-CNPrTEOS, important D-μ-SPE parameters were comprehensively optimized. The optimum extraction conditions were sorbent amount, 40 mg; extraction time, 5 min; desorption time; 5 min; sample volume, 15 mL; sample pH 2.0; and salt addition, 2.5% (w/v). The feasibility of the developed method was evaluated using spiked tap water, lake water, river water and waste water samples. Results showed that ketoprofen and ibuprofen were linear in the range of 1.0-1000 μg L -1 whilst diclofenac and mefenamic acid were linear in the range 0.8-500 μg L -1 . The results also showed good detection limits for the studied NSAIDs in the range of 0.21-0.51 μg L -1 and good recoveries for spiked water samples in the range of 85.1-106.4%. The MS-CNPrTEOS proved a promising dispersive sorbent and applicable to facile and rapid assay of NSAIDs in water samples. Copyright © 2017 Elsevier B.V. All rights reserved.

Drug screening in medical examiner casework by high-resolution mass spectrometry (UPLC-MSE-TOF).

PubMed

Rosano, Thomas G; Wood, Michelle; Ihenetu, Kenneth; Swift, Thomas A

2013-10-01

Postmortem drug findings yield important analytical evidence in medical examiner casework, and chromatography coupled with nominal mass spectrometry (MS) serves as the predominant general unknown screening approach. We report screening by ultra performance liquid chromatography (UPLC) coupled with hybrid quadrupole time-of-flight mass spectrometer (MS(E)-TOF), with comparison to previously validated nominal mass UPLC-MS and UPLC-MS-MS methods. UPLC-MS(E)-TOF screening for over 950 toxicologically relevant drugs and metabolites was performed in a full-spectrum (m/z 50-1,000) mode using an MS(E) acquisition of both molecular and fragment ion data at low (6 eV) and ramped (10-40 eV) collision energies. Mass error averaged 1.27 ppm for a large panel of reference drugs and metabolites. The limit of detection by UPLC-MS(E)-TOF ranges from 0.5 to 100 ng/mL and compares closely with UPLC-MS-MS. The influence of column recovery and matrix effect on the limit of detection was demonstrated with ion suppression by matrix components correlating closely with early and late eluting reference analytes. Drug and metabolite findings by UPLC-MS(E)-TOF were compared with UPLC-MS and UPLC-MS-MS analyses of postmortem blood in 300 medical examiner cases. Positive findings by all methods totaled 1,528, with a detection rate of 57% by UPLC-MS, 72% by UPLC-MS-MS and 80% by combined UPLC-MS and UPLC-MS-MS screening. Compared with nominal mass screening methods, UPLC-MS(E)-TOF screening resulted in a 99% detection rate and, in addition, offered the potential for the detection of nontargeted analytes via high-resolution acquisition of molecular and fragment ion data.

Top-Down LESA Mass Spectrometry Protein Analysis of Gram-Positive and Gram-Negative Bacteria

NASA Astrophysics Data System (ADS)

Kocurek, Klaudia I.; Stones, Leanne; Bunch, Josephine; May, Robin C.; Cooper, Helen J.

2017-10-01

We have previously shown that liquid extraction surface analysis (LESA) mass spectrometry (MS) is a technique suitable for the top-down analysis of proteins directly from intact colonies of the Gram-negative bacterium Escherichia coli K-12. Here we extend the application of LESA MS to Gram-negative Pseudomonas aeruginosa PS1054 and Gram-positive Staphylococcus aureus MSSA476, as well as two strains of E. coli (K-12 and BL21 mCherry) and an unknown species of Staphylococcus. Moreover, we demonstrate the discrimination between three species of Gram-positive Streptococcus ( Streptococcus pneumoniae D39, and the viridans group Streptococcus oralis ATCC 35037 and Streptococcus gordonii ATCC35105), a recognized challenge for matrix-assisted laser desorption ionization time-of-flight MS. A range of the proteins detected were selected for top-down LESA MS/MS. Thirty-nine proteins were identified by top-down LESA MS/MS, including 16 proteins that have not previously been observed by any other technique. The potential of LESA MS for classification and characterization of novel species is illustrated by the de novo sequencing of a new protein from the unknown species of Staphylococcus. [Figure not available: see fulltext.

Identification of chemical markers in Cordyceps sinensis by HPLC-MS/MS.

PubMed

Hu, Hankun; Xiao, Ling; Zheng, Baogen; Wei, Xin; Ellis, Alexis; Liu, Yi-Ming

2015-10-01

Authentication and quality assessment of Cordyceps sinensis, a precious and pricey natural product that offers a variety of health benefits, is highly significant. To identify effective chemical markers, authentic C. sinensis was thoroughly screened by using HPLC-MS/MS. In addition to many previously reported ingredients, two glycosides, i.e., cyclo-Ala-Leu-rhamnose and Phe-o-glucose, were detected for the first time in this material. Six ingredients detected, including cordycepin, D-mannitol, Phe, Phe-o-glucose, cyclo-Gly-Pro, and cyclo-Ala-Leu-rhamnose, were selected as a collection of chemical markers. An HPLC-MS/MS method was developed to simultaneously quantify them with sensitivity and specificity. The method had limits of detection ranging from 0.008 μg mL(-1) for cordycepin to 0.75 μg mL(-1) for cyclo-Gly-Pro. Recovery was found between 96 and 103 % in all tests. To evaluate the effectiveness of the marker collection proposed, five authentic C. sinensis samples and five samples of its substitutes were analyzed. Cordycepin, D-mannitol, and Phe were found present in all samples. The contents ranged from 0.0076 to 0.029 % (w/w) for cordycepin, 0.33 to 18.9 % for mannitol, and 0.0013 to 0.642 % for Phe. Interestingly, the two glycosides, Phe-o-glucose and cyclo-Ala-Leu-rhamnose, were detected only in authentic C. sinensis samples. These results indicated that the proposed protocol based on HPLC-MS/MS quantification of the markers might have a great potential in authentication and quality assessment of C. sinensis. Graphical abstract Chemical markers of C. sinensis identified in this work.

LC-MS/MS method for the determination of haemanthamine in rat plasma, bile and urine and its application to a pilot pharmacokinetic study.

PubMed

Hroch, Miloš; Mičuda, Stanislav; Havelek, Radim; Cermanová, Jolana; Cahlíková, Lucie; Hošťálková, Anna; Hulcová, Daniela; Řezáčová, Martina

2016-07-01

Evidence gathered in various studies points to the fact that haemanthamine, an isoquinoline alkaloid, has multiple medicinally interesting characteristics, including antitumor, antileukemic, antioxidant, antiviral, anticonvulsant and antimalarial activity. This work presents, for the first time, a universal LC-MS/MS method for analysis of haemanthamine in plasma, bile and urine which has been verified in a pilot pharmacokinetic experiment on rats. Chromatographic separation was performed on a pentafluorophenyl core-shell column in gradient elution mode with a mobile phase consisting of acetonitrile-methanol-ammonium formate buffer. A sample preparation based on liquid-liquid extraction with methyl tert-butyl ether was employed with ambelline used as an internal standard. Quantification was performed using LC-MS-ESI(+) in Selected Reaction Monitoring mode. The method was validated according to the European Medicines Agency guideline in a concentration range of 0.1-10 μmol/L in plasma, bile and urine. The concentration-time profiles of haemanthamine in plasma, bile and urine after a single i.v. bolus of 10 mg/kg have been described for the first time. The presented study addresses the lack of information on haemanthamine pharmacokinetics and also introduces a new universal method of haemanthamine analysis in complex biological matrices. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

Phenolic profiling of the skin, pulp and seeds of Albariño grapes using hybrid quadrupole time-of-flight and triple-quadrupole mass spectrometry.

PubMed

Di Lecce, Giuseppe; Arranz, Sara; Jáuregui, Olga; Tresserra-Rimbau, Anna; Quifer-Rada, Paola; Lamuela-Raventós, Rosa M

2014-02-15

This paper describes for the first time a complete characterisation of the phenolic compounds in different anatomical parts of the Albariño grape. The application of high-performance liquid chromatography coupled with two complementary techniques, hybrid quadrupole time-of-flight and triple-quadrupole mass spectrometry, allowed the phenolic composition of the Albariño grape to be unambiguously identified and quantified. A more complete phenolic profile was obtained by product ion and precursor ion scans, while a neutral loss scan at 152 u enabled a fast screening of procyanidin dimers, trimers and their galloylated derivatives. The compounds were confirmed by accurate mass measurements in QqToF-MS and QqToF-MS/MS modes at high resolution, and good fits were obtained for all investigated ions, with errors ranging from 0.2 to 4.5 mDa. To the best of our knowledge, two flavanol monomer hexosides were detected in the grape berry for the first time. Copyright © 2013 Elsevier Ltd. All rights reserved.

Combined evaluation of personality, risk and coping in MS patients: A step towards individualized treatment choice - The PeRiCoMS-Study I.

PubMed

Bsteh, G; Monz, E; Zamarian, L; Hagspiel, S; Hegen, H; Auer, M; Wurth, S; Di Pauli, F; Deisenhammer, F; Berger, T

2017-05-15

Multiple sclerosis (MS) is a chronic inflammatory neurological disease requiring disease-modifying treatment (DMT). To provide patients with the optimal individual therapeutic option, treatment recommendations should be based not only on individual disease course and DMT specific benefit-risk estimates, but also on patient's individual characteristics such as personality, risk attitude and coping strategies. However, these characteristics are difficult to objectify in clinical routine practice without the support of appropriate evaluation instruments. To identify and to assemble an objective test battery measuring personality, risk attitude and coping strategies in MS patients. A comprehensive literature search was performed to obtain all questionnaires assessing personality, risk attitude and coping strategies. Availability in German language, validation in a published normative collective and a reliability of >0.70 were required for our purposes. Based on these criteria, we chose the Big-Five-Personality Test, UPPS Impulsive Behaviour Scale, Domain-Specific Risk-Taking scale (DOSPERT), Brief-COPE and Stress & Coping Inventory (SCI). Results were compared to published normative controls of the respective questionnaires. Out of 22 MS patients (7 males, 15 females) participating in this study, 19 (86.4%) completed all questionnaires. The median completion time was 45min (min-max range: 25-60min). The median scores of the MS group were within the average range of published control samples in all questionnaires. We report that traits of personality, risk attitude and coping strategies can be effectively and feasibly tested in MS patients by the instruments used in our exploratory study. There were no differences between MS patients and healthy controls, thus enabling assessment without being influenced by the diagnosis of MS. After validation in a larger cohort the "PeRiCoMS"-battery will be useful as another step towards a more individualized shared-decision-making in every day routine practice. Copyright © 2017 Elsevier B.V. All rights reserved.

Development of N_2O-MTV for low-speed flow and in-situ deployment to an integral effect test facility

NASA Astrophysics Data System (ADS)

André, Matthieu A.; Burns, Ross A.; Danehy, Paul M.; Cadell, Seth R.; Woods, Brian G.; Bardet, Philippe M.

2018-01-01

A molecular tagging velocity (MTV) technique is developed to non-intrusively measure velocity in an integral effect test (IET) facility simulating a high-temperature helium-cooled nuclear reactor in accident scenarios. In these scenarios, the velocities are expected to be low, on the order of 1 m/s or less, which forces special requirements on the MTV tracer selection. Nitrous oxide (N_2O) is identified as a suitable seed gas to generate NO tracers capable of probing the flow over a large range of pressure, temperature, and flow velocity. The performance of N_2O-MTV is assessed in the laboratory at temperature and pressure ranging from 295 to 781 K and 1 to 3 atm. MTV signal improves with a temperature increase, but decreases with a pressure increase. Velocity precision down to 0.004 m/s is achieved with a probe time of 40 ms at ambient pressure and temperature. Measurement precision is limited by tracer diffusion, and absorption of the tag laser beam by the seed gas. Processing by cross-correlation of single-shot images with high signal-to-noise ratio reference images improves the precision by about 10% compared to traditional single-shot image correlations. The instrument is then deployed to the IET facility. Challenges associated with heat, vibrations, safety, beam delivery, and imaging are addressed in order to successfully operate this sensitive instrument in-situ. Data are presented for an isothermal depressurized conduction cooldown. Velocity profiles from MTV reveal a complex flow transient driven by buoyancy, diffusion, and instability taking place over short (<1 s) and long (>30 min) time scales at sub-meter per second speed. The precision of the in-situ results is estimated at 0.027, 0.0095, and 0.006 m/s for a probe time of 5, 15, and 35 ms, respectively.

Quantitative analysis of factor P (Properdin) in monkey serum using immunoaffinity capturing in combination with LC-MS/MS.

PubMed

Gao, Xinliu; Lin, Hui; Krantz, Carsten; Garnier, Arlette; Flarakos, Jimmy; Tse, Francis L S; Li, Wenkui

2016-01-01

Factor P (Properdin), an endogenous glycoprotein, plays a key role in innate immune defense. Its quantification is important for understanding the pharmacodynamics (PD) of drug candidate(s). In the present work, an immunoaffinity capturing LC-MS/MS method has been developed and validated for the first time for the quantification of factor P in monkey serum with a dynamic range of 125 to 25,000 ng/ml using the calibration standards and QCs prepared in factor P depleted monkey serum. The intra- and inter-run precision was ≤7.2% (CV) and accuracy within ±16.8% (%Bias) across all QC levels evaluated. Results of other evaluations (e.g., stability) all met the acceptance criteria. The validated method was robust and implemented in support of a preclinical PK/PD study.

Flow characteristics of an inclined air-curtain range hood in a draft

PubMed Central

CHEN, Jia-Kun

2015-01-01

The inclined air-curtain technology was applied to build an inclined air-curtain range hood. A draft generator was applied to affect the inclined air-curtain range hood in three directions: lateral (θ=0°), oblique (θ=45°), and front (θ=90°). The three suction flow rates provided by the inclined air-curtain range hood were 10.1, 10.9, and 12.6 m3/min. The laser-assisted flow visualization technique and the tracer-gas test method were used to investigate the performance of the range hood under the influence of a draft. The results show that the inclined air-curtain range hood has a strong ability to resist the negative effect of a front draft until the draft velocity is greater than 0.5 m/s. The oblique draft affected the containment ability of the inclined air-curtain range hood when the draft velocity was larger than 0.3 m/s. When the lateral draft effect was applied, the capture efficiency of the inclined air-curtain range hood decreased quickly in the draft velocity from 0.2 m/s to 0.3 m/s. However, the capture efficiencies of the inclined air-curtain range hood under the influence of the front draft were higher than those under the influence of the oblique draft from 0.3 m/s to 0.5 m/s. PMID:25810445

Flow characteristics of an inclined air-curtain range hood in a draft.

PubMed

Chen, Jia-Kun

2015-01-01

The inclined air-curtain technology was applied to build an inclined air-curtain range hood. A draft generator was applied to affect the inclined air-curtain range hood in three directions: lateral (θ=0°), oblique (θ=45°), and front (θ=90°). The three suction flow rates provided by the inclined air-curtain range hood were 10.1, 10.9, and 12.6 m(3)/min. The laser-assisted flow visualization technique and the tracer-gas test method were used to investigate the performance of the range hood under the influence of a draft. The results show that the inclined air-curtain range hood has a strong ability to resist the negative effect of a front draft until the draft velocity is greater than 0.5 m/s. The oblique draft affected the containment ability of the inclined air-curtain range hood when the draft velocity was larger than 0.3 m/s. When the lateral draft effect was applied, the capture efficiency of the inclined air-curtain range hood decreased quickly in the draft velocity from 0.2 m/s to 0.3 m/s. However, the capture efficiencies of the inclined air-curtain range hood under the influence of the front draft were higher than those under the influence of the oblique draft from 0.3 m/s to 0.5 m/s.

Lipophilic metabolite profiling of maize and sorghum seeds and seedlings, and their pest spotted stem borer larvae: a standardized GC-MS based approach.

PubMed

Kumar, Sandeep; Dhillon, Mukesh K

2015-03-01

In order to better understand the biochemical interactions and to identify new biomarkers for plant resistance against insects, we proposed a suitable lipophilic profiling method for insects and their host plants. The critical components of GC-MS based analysis are: sample amount, extraction, derivatization, temperature gradient, run time, and identification of peaks. For lipophilic metabolite profiling of maize and sorghum, and their insect pest, spotted stem borer larvae, we recommend 100 mg sample weight for seeds and insect samples (whole insect body), and 200 mg for seedlings. Maize and sorghum seeds required less time for fat extraction in comparison to their seedlings and the pest fed on these seedlings. GC-MS was standardized for better separation and intensity of peaks using different temperature gradients in the range of 180-300 C. A total of 48 lipophilic compounds encompassing various classes based on their functional groups such as fatty acids, fatty alcohols, hydrocarbons, sterols and terpenoids, vitamin derivative, etc. were separated in the seedlings (30), seeds (14), and the pest (26) in the retention time range of 3.22 to 29.41 min. This method could be useful to study nutritional aspects of different field crops in relation to various stresses apart from the analysis of lipophilic compounds for better understanding of insect-plant interactions.

Direct observation of surface ethyl to ethane interconversion upon C2H4 hydrogenation over Pt/Al2O3 catalyst by time-resolved FT-IR spectroscopy.

PubMed

Wasylenko, Walter; Frei, Heinz

2005-09-08

Time-resolved FT-IR spectra of ethylene hydrogenation over alumina-supported Pt catalyst were recorded at 25 ms resolution in the temperature range of 323-473 K using various H2 concentrations (1 atm total gas pressure). Surface ethyl species (2870 and 1200 cm(-1)) were detected at all temperatures along with the gas-phase ethane product (2954 and 2893 cm(-1)). The CH3CH2Pt growth was instantaneous on the time scale of 25 ms under all experimental conditions. At 323 K, the decay time of surface ethyl (122 +/- 10 ms) coincides with the rise time of ethane (144 +/- 14 ms). This establishes direct kinetic evidence for surface ethyl as the relevant reaction intermediate. Such a direct link between the temporal behavior of an unstable surface intermediate and the final product in a heterogeneous catalytic system has not been demonstrated before. A fraction (25%) of the asymptotic ethane growth at 323 K is prompt, indicating that there are surface ethyl species that react much faster than the majority of the CH3CH2Pt intermediates. The dispersive kinetics is attributed to the varying strength of interaction of the ethyl species with the Pt surface caused by heterogeneity of the surface environment. At 473 K, the majority of ethyl intermediates are hydrogenated prior to the recording of the first time slice (24 ms), and a correspondingly large prompt growth of ethane is observed. The yield and kinetics of the surface ethylidyne are in agreement with the known spectator nature of this species.

Reliable Collection of Real-Time Patient Physiologic Data from less Reliable Networks: a "Monitor of Monitors" System (MoMs).

PubMed

Hu, Peter F; Yang, Shiming; Li, Hsiao-Chi; Stansbury, Lynn G; Yang, Fan; Hagegeorge, George; Miller, Catriona; Rock, Peter; Stein, Deborah M; Mackenzie, Colin F

2017-01-01

Research and practice based on automated electronic patient monitoring and data collection systems is significantly limited by system down time. We asked whether a triple-redundant Monitor of Monitors System (MoMs) to collect and summarize key information from system-wide data sources could achieve high fault tolerance, early diagnosis of system failure, and improve data collection rates. In our Level I trauma center, patient vital signs(VS) monitors were networked to collect real time patient physiologic data streams from 94 bed units in our various resuscitation, operating, and critical care units. To minimize the impact of server collection failure, three BedMaster® VS servers were used in parallel to collect data from all bed units. To locate and diagnose system failures, we summarized critical information from high throughput datastreams in real-time in a dashboard viewer and compared the before and post MoMs phases to evaluate data collection performance as availability time, active collection rates, and gap duration, occurrence, and categories. Single-server collection rates in the 3-month period before MoMs deployment ranged from 27.8 % to 40.5 % with combined 79.1 % collection rate. Reasons for gaps included collection server failure, software instability, individual bed setting inconsistency, and monitor servicing. In the 6-month post MoMs deployment period, average collection rates were 99.9 %. A triple redundant patient data collection system with real-time diagnostic information summarization and representation improved the reliability of massive clinical data collection to nearly 100 % in a Level I trauma center. Such data collection framework may also increase the automation level of hospital-wise information aggregation for optimal allocation of health care resources.

Persistence to disease-modifying therapies for multiple sclerosis in a Canadian cohort

PubMed Central

Melesse, Dessalegn Y; Marrie, Ruth Ann; Blanchard, James F; Yu, Bo Nancy; Evans, Charity

2017-01-01

Purpose To examine the long-term persistence to the first-line injectable disease-modifying therapies (DMTs) for multiple sclerosis (MS) and to identify the factors associated with nonpersistence. Patients and methods We used population-based administrative data from Manitoba, Canada. All adult subjects who were diagnosed with MS and dispensed a first-line injectable DMT (beta-interferon-1b, beta-interferon-1a, and glatiramer acetate) between 1996 and 2011 and had a minimum of 1 year of follow-up were included. The primary outcome was the median time to discontinuation of any DMT. The associations between potential predictors and persistence were estimated using multivariable Cox-proportional hazard models. Results Overall, 721 subjects were followed for a median of 7.8 years (interquartile range 6.1). The median time to discontinuation of all first-line DMTs was 4.2 years (25th and 75th percentile: 1.7, 10.6 years). Of the 451 (62.6%) subjects who discontinued their DMT during the study period, 259 (57.4%) eventually resumed or restarted a DMT. Subjects who were younger when starting a DMT, had prior MS-related hospitalizations, were more recently diagnosed with MS, or had a greater lag time between their MS diagnosis and DMT initiation were more likely to discontinue therapy. Conclusion Over half of the individuals receiving a DMT for MS in Manitoba remained on therapy for at least 4 years. DMT discontinuation occurred in 60% of the cohort, but most restarted a DMT within 1 year. While not all of the factors identified with discontinuing DMT are modifiable, they may help practitioners enhance MS care by identifying individuals who may be at particular risk for DMT discontinuation. PMID:28721023

An On-Line Solid Phase Extraction-Liquid Chromatography-Tandem Mass Spectrometry Method for the Determination of Perfluoroalkyl Acids in Drinking and Surface Waters

PubMed Central

Mazzoni, Michela; Rusconi, Marianna; Valsecchi, Sara; Martins, Claudia P. B.; Polesello, Stefano

2015-01-01

An UHPLC-MS/MS multiresidue method based on an on-line solid phase extraction (SPE) procedure was developed for the simultaneous determination of 9 perfluorinated carboxylates (from 4 to 12 carbon atoms) and 3 perfluorinated sulphonates (from 4 to 8 carbon atoms). This work proposes using an on-line solid phase extraction before chromatographic separation and analysis to replace traditional methods of off-line SPE before direct injection to LC-MS/MS. Manual sample preparation was reduced to sample centrifugation and acidification, thus eliminating several procedural errors and significantly reducing time-consuming and costs. Ionization suppression between target perfluorinated analytes and their coeluting SIL-IS were detected for homologues with a number of carbon atoms less than 9, but the quantitation was not affected. Total matrix effect corrected by SIL-IS, inclusive of extraction efficacy, and of ionization efficiency, ranged between −34 and +39%. The percentage of recoveries, between 76 and 134%, calculated in different matrices (tap water and rivers impacted by different pollutions) was generally satisfactory. LODs and LOQs of this on-line SPE method, which also incorporate recovery losses, ranged from 0.2 to 5.0 ng/L and from 1 to 20 ng/L, respectively. Validated on-line SPE-LC/MS/MS method has been applied in a wide survey for the determination of perfluoroalkyl acids in Italian surface and ground waters. PMID:25834752

A UPLC-MS/MS method for simultaneous determination of five flavonoids from Stellera chamaejasme L. in rat plasma and its application to a pharmacokinetic study.

PubMed

Li, Yun-Qing; Li, Cheng-Jian; Lv, Lei; Cao, Qing-Qing; Qian, Xian; Li, Si Wei; Wang, Hui; Zhao, Liang

2018-06-01

Stellera chamaejasme L. has been used as a traditional Chinese medicine for the treatment of scabies, tinea, stubborn skin ulcers, chronic tracheitis, cancer and tuberculosis. A sensitive and selective ultra-high liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed and validated for the simultaneous determination of five flavonoids (stelleranol, chamaechromone, neochamaejasmin A, chamaejasmine and isochamaejasmin) of S. chamaejasme L. in rat plasma. Chromatographic separation was accomplished on an Agilent Poroshell 120 EC-C 18 column (2.1 × 100 mm, 2.7 μm) with gradient elution at a flow rate of 0.4 mL/min and the total analysis time was 7 min. The analytes were detected using multiple reaction monitoring in positive ionization mode. The samples were prepared by liquid-liquid extraction with ethyl acetate. The UPLC-MS/MS method was validated for specificity, linearity, sensitivity, accuracy and precision, recovery, matrix effect and stability. The validated method exhibited good linearity (r ≥ 0.9956), and the lower limits of quantification ranged from 0.51 to 0.64 ng/mL for five flavonoids. The intra- and inter-day precision were both <10.2%, and the accuracy ranged from -11.79 to 9.21%. This method was successfully applied to a pharmacokinetic study of five flavonoids in rats after oral administration of ethyl acetate extract of S. chamaejasme L. Copyright © 2018 John Wiley & Sons, Ltd.

Exploratory characterization of the unsaponifiable fraction of tunisian virgin olive oils by a global approach with HPLC-APCI-IT MS/MS analysis.

PubMed

Zarrouk, Wissem; Carrasco-Pancorbo, Alegría; Segura-Carretero, Antonio; Fernández-Gutiérrez, Alberto; Zarrouk, Mokhtar

2010-05-26

The unsaponifiable fraction of six Tunisian monovarietal virgin olive oils from the region of Medenine was evaluated within a single chromatographic run by using HPLC-APCI-tandem MS. Separation of the compounds under study was achieved by the RP-LC method, giving a reasonable analysis time and good resolution. Detection was done by an ion trap (working alternatively in MS and MS/MS modes), the fact which made our method suitable to unequivocally identify a high number of compounds belonging to different families of the unsaponifiable fraction of oil and to carry out their reliable and sensitive quantification. A great amount of qualitative information was generated in every analysis, although we focused on the quantification of sterols, tocopherols, and triterpenic dialcohols since their standards were commercially available. The limits of detections achieved were within the range of 1.21 and 10.31 microg/kg for sitostanol and beta-sitosterol, respectively. Significant differences were observed in the composition of the studied olive cultivars. Jemri Ben Guerdane oil was the richest one in terms of all of the sterols under study. alpha-Tocopherol was the main vitamin E isomer in all samples, ranging from 70.14 to 130.72 mg/kg. Principal component analysis (PCA) and cluster analysis were applied to the whole data set in order to explore the distribution of the olive cultivars according to their oil composition.

Development of a pressurized liquid extraction-solid-phase extraction followed by liquid chromatography-electrospray ionization tandem mass spectrometry method for the quantitative determination of benzoxazolinones and their degradation products in agricultural soil.

PubMed

Villagrasa, M; Guillamón, M; Navarro, A; Eljarrat, E; Barceló, D

2008-02-01

A new analytical method for the quantitative determination of benzoxazolinones and their degradation products in agricultural soils based on the use of pressurized liquid extraction (PLE) followed by solid-phase extraction (SPE) and then instrumental determination using liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS-MS) is described. Using this method, the characterization, separation and quantitative detection of a mixture of two benzoxazolinones, benzoxazolin-2-one (BOA) and 6-methoxybenzoxazolin-2-one (MBOA) and their degradation products, 2-aminophenol (APH), N-(2-hydroxyphenyl)malonamic acid (HMPMA), 2-amino-3-H-phenoxazin-3-one (APO), 9-methoxy-2-amino-3-H-phenoxazin-3-one (AMPO), 2-acetylamino-3-H-phenoxazin-3-one (AAPO) and 2-acetylamino-9-methoxy-2-amino-3-H-phenoxazin-3-one (AAMPO) was achieved. The complete LC-ESI-MS-MS precursor-product ion fragmentation pathways for the degradation products of benzoxazolinones are described for the first time. Quantitative analysis was done in the multiple reaction mode using two specific combinations of precursor-product ion transitions for each compound. The optimized method was quality assessed by the measure of parameter as recovery, linearity, sensitivity, repeatability and reproducibility. Recoveries of the analytes ranged from 53 to 123%. The developed method offered improvements to the sensitivity as compared with our previously LC-MS method, with detection limits down to 2.4-21 ng/g of dry weight. This achievement allows us to identify and quantify for the first time degradation products of benzoxazolinones in real agricultural soil samples. Analytes were found in the range of 20.6-149 ng/g dry weight.

Relationship between slow visual processing and reading speed in people with macular degeneration

PubMed Central

Cheong, Allen MY; Legge, Gordon E; Lawrence, Mary G; Cheung, Sing-Hang; Ruff, Mary A

2007-01-01

Purpose People with macular degeneration (MD) often read slowly even with adequate magnification to compensate for acuity loss. Oculomotor deficits may affect reading in MD, but cannot fully explain the substantial reduction in reading speed. Central-field loss (CFL) is often a consequence of macular degeneration, necessitating the use of peripheral vision for reading. We hypothesized that slower temporal processing of visual patterns in peripheral vision is a factor contributing to slow reading performance in MD patients. Methods Fifteen subjects with MD, including 12 with CFL, and five age-matched control subjects were recruited. Maximum reading speed and critical print size were measured with RSVP (Rapid Serial Visual Presentation). Temporal processing speed was studied by measuring letter-recognition accuracy for strings of three randomly selected letters centered at fixation for a range of exposure times. Temporal threshold was defined as the exposure time yielding 80% recognition accuracy for the central letter. Results Temporal thresholds for the MD subjects ranged from 159 to 5881 ms, much longer than values for age-matched controls in central vision (13 ms, p<0.01). The mean temporal threshold for the 11 MD subjects who used eccentric fixation (1555.8 ± 1708.4 ms) was much longer than the mean temporal threshold (97.0 ms ± 34.2 ms, p<0.01) for the age-matched controls at 10° in the lower visual field. Individual temporal thresholds accounted for 30% of the variance in reading speed (p<0.05). Conclusion The significant association between increased temporal threshold for letter recognition and reduced reading speed is consistent with the hypothesis that slower visual processing of letter recognition is one of the factors limiting reading speed in MD subjects. PMID:17881032

Enhancing reproducibility of SALDI MS detection by concentrating analytes within laser spot.

PubMed

Teng, Fei; Zhu, Qunyan; Wang, Yalei; Du, Juan; Lu, Nan

2018-03-01

Surface-assisted laser desorption/ionization time-of-flight mass spectrometry (SALDI TOF MS) has become one of the most important analytical methods due to its less interference at low molecular weight range. However, it is still a challenge to obtain a good reproducibility of SALDI TOF MS because of the inhomogeneous distribution of analyte molecules induced by coffee ring effect. We propose a universal and reliable method to eliminate the coffee ring effect by concentrating all the analyte molecules within the laser spot. This method exhibits an excellent reproducibility of spot-to-spot and substrate-to-substrate, and the relative standard deviations (RSDs) for different concentrations are lower than 12.6%. It also performs good linear dependency (R 2 > 0.98) in the log-log plot with the concentration range of 1nM to 1μM, and the limit of detection for R6G is down to 1fmol. Copyright © 2017 Elsevier B.V. All rights reserved.

Fast Enzymatic Processing of Proteins for MS Detection with a Flow-through Microreactor

PubMed Central

Lazar, Iulia M.; Deng, Jingren; Smith, Nicole

2016-01-01

The vast majority of mass spectrometry (MS)-based protein analysis methods involve an enzymatic digestion step prior to detection, typically with trypsin. This step is necessary for the generation of small molecular weight peptides, generally with MW < 3,000-4,000 Da, that fall within the effective scan range of mass spectrometry instrumentation. Conventional protocols involve O/N enzymatic digestion at 37 ºC. Recent advances have led to the development of a variety of strategies, typically involving the use of a microreactor with immobilized enzymes or of a range of complementary physical processes that reduce the time necessary for proteolytic digestion to a few minutes (e.g., microwave or high-pressure). In this work, we describe a simple and cost-effective approach that can be implemented in any laboratory for achieving fast enzymatic digestion of a protein. The protein (or protein mixture) is adsorbed on C18-bonded reversed-phase high performance liquid chromatography (HPLC) silica particles preloaded in a capillary column, and trypsin in aqueous buffer is infused over the particles for a short period of time. To enable on-line MS detection, the tryptic peptides are eluted with a solvent system with increased organic content directly in the MS ion source. This approach avoids the use of high-priced immobilized enzyme particles and does not necessitate any aid for completing the process. Protein digestion and complete sample analysis can be accomplished in less than ~3 min and ~30 min, respectively. PMID:27078683

Fast Enzymatic Processing of Proteins for MS Detection with a Flow-through Microreactor.

PubMed

Lazar, Iulia M; Deng, Jingren; Smith, Nicole

2016-04-06

The vast majority of mass spectrometry (MS)-based protein analysis methods involve an enzymatic digestion step prior to detection, typically with trypsin. This step is necessary for the generation of small molecular weight peptides, generally with MW < 3,000-4,000 Da, that fall within the effective scan range of mass spectrometry instrumentation. Conventional protocols involve O/N enzymatic digestion at 37 ºC. Recent advances have led to the development of a variety of strategies, typically involving the use of a microreactor with immobilized enzymes or of a range of complementary physical processes that reduce the time necessary for proteolytic digestion to a few minutes (e.g., microwave or high-pressure). In this work, we describe a simple and cost-effective approach that can be implemented in any laboratory for achieving fast enzymatic digestion of a protein. The protein (or protein mixture) is adsorbed on C18-bonded reversed-phase high performance liquid chromatography (HPLC) silica particles preloaded in a capillary column, and trypsin in aqueous buffer is infused over the particles for a short period of time. To enable on-line MS detection, the tryptic peptides are eluted with a solvent system with increased organic content directly in the MS ion source. This approach avoids the use of high-priced immobilized enzyme particles and does not necessitate any aid for completing the process. Protein digestion and complete sample analysis can be accomplished in less than ~3 min and ~30 min, respectively.

Simultaneous determination of codeine, ephedrine, guaiphenesin and chlorpheniramine in beagle dog plasma using high performance liquid chromatography coupled with tandem mass spectrometric detection: application to a bioequivalence study.

PubMed

Hu, Ziyan; Zou, Qiaogen; Tian, Jixin; Sun, Lili; Zhang, Zunjian

2011-12-15

A rapid and sensitive method based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the simultaneous determination of codeine, ephedrine, guaiphenesin and chlorpheniramine in beagle dog plasma has been developed and validated. Following liquid-liquid extraction, the analytes were separated on a reversed-phase C(18) column (150 mm × 2.0 mm, 3 μm) using formic acid:10 mM ammonium acetate:methanol (0.2:62:38, v/v/v) as mobile phase at a flow rate of 0.2 mL/min and analyzed by a triple-quadrupole mass spectrometer in the selected reaction monitoring (SRM) mode. The method was linear for all analytes over the following concentration (ng/mL) ranges: codeine 0.08-16; ephedrine 0.8-160; guaiphenesin 80-16,000; chlorpheniramine 0.2-40. Acceptable precision and accuracy were obtained for concentrations over the standard curve range. It is the first time that the validated HPLC-MS/MS method was successfully applied to a bioequivalence study in 6 healthy beagle dogs. Copyright © 2011 Elsevier B.V. All rights reserved.

LC-ESI-MS/MS determination of 4-methylpyrazole in dog plasma and its application to a pharmacokinetic study in dogs.

PubMed

Chandrasekhar, Devaraj V; Suresh, Ponnayyan Sulochana; Dittakavi, Sreekanth; Hiremath, Rakesh A; Bhamidipati, Ravi Kanth; Richter, Wolfgang; Srinivas, Nuggehally R; Mullangi, Ramesh

2018-02-01

A simple, specific, sensitive and rapid LC-ESI-MS/MS method has been developed and validated for the quantification of 4-methylpyrazole in dog plasma using N-methylnicotinamide-d 4 as an internal standard (IS) as per regulatory guidelines. Sample preparation was accomplished through a simple protein precipitation. Chromatographic separation of 4-methylpyrazole and the IS was performed on a monolithic (Chromolith RP 18e ) column using an isocratic mobile phase comprising 0.2% formic acid in water and acetonitrile (20:80, v/v) at a flow rate of 1.0 mL/min. Elution of 4-methylpyrazole and the IS occurred at ~1.60 and 1.56 min, respectively. The total chromatographic run time was 3.2 min. A linear response function was established in the concentration range of 4.96-4955 ng/mL. The intra- and inter-day accuracy and precision were in the ranges 1.81-12.9 and 3.80-11.1%, respectively. This novel method has been applied to a pharmacokinetic study in dogs. Copyright © 2017 John Wiley & Sons, Ltd.

Slow speed—fast motion: time-lapse recordings in physics education

NASA Astrophysics Data System (ADS)

Vollmer, Michael; Möllmann, Klaus-Peter

2018-05-01

Video analysis with a 30 Hz frame rate is the standard tool in physics education. The development of affordable high-speed-cameras has extended the capabilities of the tool for much smaller time scales to the 1 ms range, using frame rates of typically up to 1000 frames s-1, allowing us to study transient physics phenomena happening too fast for the naked eye. Here we want to extend the range of phenomena which may be studied by video analysis in the opposite direction by focusing on much longer time scales ranging from minutes, hours to many days or even months. We discuss this time-lapse method, needed equipment and give a few hints of how to produce respective recordings for two specific experiments.

Single solid phase extraction method for the simultaneous analysis of polar and non-polar pesticides in urine samples by gas chromatography and ultra high pressure liquid chromatography coupled to tandem mass spectrometry.

PubMed

Cazorla-Reyes, Rocío; Fernández-Moreno, José Luis; Romero-González, Roberto; Frenich, Antonia Garrido; Vidal, José Luis Martínez

2011-07-15

A new multiresidue method has been developed and validated for the simultaneous extraction of more than two hundred pesticides, including non-polar and polar pesticides (carbamates, organochlorine, organophosphorous, pyrethroids, herbicides and insecticides) in urine at trace levels by gas and ultra high pressure liquid chromatography coupled to ion trap and triple quadrupole mass spectrometry, respectively (GC-IT-MS/MS, UHPLC-QqQ-MS/MS). Non-polar and polar pesticides were simultaneously extracted from urine samples by a simple and fast solid phase extraction (SPE) procedure using C(18) cartridges as sorbent, and dichloromethane as elution solvent. Recovery was in the range of 60-120%. Precision values expressed as relative standard deviation (RSD) were lower than 25%. Identification and confirmation of the compounds were performed by the use of retention time windows, comparison of spectra (GC-amenable compounds) or the estimation of the ion ratio (LC-amenable compounds). For GC-amenable pesticides, limits of detection (LODs) ranged from 0.001 to 0.436 μg L(-1) and limits of quantification (LOQs) from 0.003 to 1.452 μg L(-1). For LC-amenable pesticides, LODs ranged from 0.003 to 1.048 μg L(-1) and LOQs ranged from 0.011 to 3.494 μg L(-1). Finally, the optimized method was applied to the analysis of fourteen real samples of infants from agricultural population. Some pesticides such as methoxyfenozide, tebufenozide, piperonyl butoxide and propoxur were found at concentrations ranged from 1.61 to 24.4 μg L(-1), whereas methiocarb sulfoxide was detected at trace levels in two samples. Copyright © 2011 Elsevier B.V. All rights reserved.

Computational model of retinal photocoagulation and rupture

NASA Astrophysics Data System (ADS)

Sramek, Christopher; Paulus, Yannis M.; Nomoto, Hiroyuki; Huie, Phil; Palanker, Daniel

2009-02-01

In patterned scanning laser photocoagulation, shorter duration (< 20 ms) pulses help reduce thermal damage beyond the photoreceptor layer, decrease treatment time and minimize pain. However, safe therapeutic window (defined as the ratio of rupture threshold power to that of light coagulation) decreases for shorter exposures. To quantify the extent of thermal damage in the retina, and maximize the therapeutic window, we developed a computational model of retinal photocoagulation and rupture. Model parameters were adjusted to match measured thresholds of vaporization, coagulation, and retinal pigment epithelial (RPE) damage. Computed lesion width agreed with histological measurements in a wide range of pulse durations and power. Application of ring-shaped beam profile was predicted to double the therapeutic window width for exposures in the range of 1 - 10 ms.

On-line LC-MS approach combining collision-induced dissociation (CID), electron-transfer dissociation (ETD), and CID of an isolated charge-reduced species for the trace-level characterization of proteins with post-translational modifications.

PubMed

Wu, Shiaw-Lin; Hühmer, Andreas F R; Hao, Zhiqi; Karger, Barry L

2007-11-01

We have expanded our recent on-line LC-MS platform for large peptide analysis to combine collision-induced dissociation (CID), electron-transfer dissociation (ETD), and CID of an isolated charge-reduced (CRCID) species derived from ETD to determine sites of phosphorylation and glycosylation modifications, as well as the sequence of large peptide fragments (i.e., 2000-10,000 Da) from complex proteins, such as beta-casein, epidermal growth factor receptor (EGFR), and tissue plasminogen activator (t-PA) at the low femtomol level. The incorporation of an additional CID activation step for a charge-reduced species, isolated from ETD fragment ions, improved ETD fragmentation when precursor ions with high m/z (approximately >1000) were automatically selected for fragmentation. Specifically, the identification of the exact phosphorylation sites was strengthened by the extensive coverage of the peptide sequence with a near-continuous product ion series. The identification of N-linked glycosylation sites in EGFR and an O-linked glycosylation site in t-PA were also improved through the enhanced identification of the peptide backbone sequence of the glycosylated precursors. The new strategy is a good starting survey scan to characterize enzymatic peptide mixtures over a broad range of masses using LC-MS with data-dependent acquisition, as the three activation steps can provide complementary information to each other. In general, large peptides can be extensively characterized by the ETD and CRCID steps, including sites of modification from the generated, near-continuous product ion series, supplemented by the CID-MS2 step. At the same time, small peptides (e.g.,

A MS-lesion pattern discrimination plot based on geostatistics.

PubMed

Marschallinger, Robert; Schmidt, Paul; Hofmann, Peter; Zimmer, Claus; Atkinson, Peter M; Sellner, Johann; Trinka, Eugen; Mühlau, Mark

2016-03-01

A geostatistical approach to characterize MS-lesion patterns based on their geometrical properties is presented. A dataset of 259 binary MS-lesion masks in MNI space was subjected to directional variography. A model function was fit to express the observed spatial variability in x, y, z directions by the geostatistical parameters Range and Sill. Parameters Range and Sill correlate with MS-lesion pattern surface complexity and total lesion volume. A scatter plot of ln(Range) versus ln(Sill), classified by pattern anisotropy, enables a consistent and clearly arranged presentation of MS-lesion patterns based on geometry: the so-called MS-Lesion Pattern Discrimination Plot. The geostatistical approach and the graphical representation of results are considered efficient exploratory data analysis tools for cross-sectional, follow-up, and medication impact analysis.

Qualitative and quantitative analysis of poly(amidoamine) dendrimers in an aqueous matrix by liquid chromatography-electrospray ionization-hybrid quadrupole/time-of-flight mass spectrometry (LC-ESI-QTOF-MS).

PubMed

Uclés, A; Ulaszewska, M M; Hernando, M D; Ramos, M J; Herrera, S; García, E; Fernández-Alba, A R

2013-07-01

This work introduces a liquid chromatography-electrospray ionization-hybrid quadrupole/time-of-flight mass spectrometry (LC-ESI-QTOF-MS)-based method for qualitative and quantitative analysis of poly(amidoamine) (PAMAM) dendrimers of generations 0 to 3 in an aqueous matrix. The multiple charging of PAMAM dendrimers generated by means of ESI has provided key advantages in dendrimer identification by assignation of charge state through high resolution of isotopic clusters. Isotopic distribution in function of abundance of isotopes (12)C and (13)C yielded valuable and complementarity data for confident characterization. A mass accuracy below 3.8 ppm for the most abundant isotopes (diagnostic ions) provided unambiguous identification of PAMAM dendrimers. Validation of the LC-ESI-QTOF-MS method and matrix effect evaluation enabled reliable and reproducible quantification. The validation parameters, limits of quantification in the range of 0.012 to 1.73 μM, depending on the generation, good linear range (R > 0.996), repeatability (RSD < 13.4%), and reproducibility (RSD < 10.9%) demonstrated the suitability of the method for the quantification of dendrimers in aqueous matrices (water and wastewater). The added selectivity, achieved by multicharge phenomena, represents a clear advantage in screening aqueous mixtures due to the fact that the matrix had no significant effect on ionization, with what is evidenced by an absence of sensitivity loss in most generations of PAMAM dendrimers. Fig Liquid chromatography-electrospray ionization-hybrid quadrupole/time of flight mass spectrometry (LC-ESI-QTOF-MS) based method for qualitative and quantitative analysis of PAMAM dendrimers in aqueous matrix.

Low-back electromyography (EMG) data-driven load classification for dynamic lifting tasks

PubMed Central

Ojeda, Lauro; Johnson, Daniel D.; Gates, Deanna; Mower Provost, Emily; Barton, Kira

2018-01-01

Objective Numerous devices have been designed to support the back during lifting tasks. To improve the utility of such devices, this research explores the use of preparatory muscle activity to classify muscle loading and initiate appropriate device activation. The goal of this study was to determine the earliest time window that enabled accurate load classification during a dynamic lifting task. Methods Nine subjects performed thirty symmetrical lifts, split evenly across three weight conditions (no-weight, 10-lbs and 24-lbs), while low-back muscle activity data was collected. Seven descriptive statistics features were extracted from 100 ms windows of data. A multinomial logistic regression (MLR) classifier was trained and tested, employing leave-one subject out cross-validation, to classify lifted load values. Dimensionality reduction was achieved through feature cross-correlation analysis and greedy feedforward selection. The time of full load support by the subject was defined as load-onset. Results Regions of highest average classification accuracy started at 200 ms before until 200 ms after load-onset with average accuracies ranging from 80% (±10%) to 81% (±7%). The average recall for each class ranged from 69–92%. Conclusion These inter-subject classification results indicate that preparatory muscle activity can be leveraged to identify the intent to lift a weight up to 100 ms prior to load-onset. The high accuracies shown indicate the potential to utilize intent classification for assistive device applications. Significance Active assistive devices, e.g. exoskeletons, could prevent back injury by off-loading low-back muscles. Early intent classification allows more time for actuators to respond and integrate seamlessly with the user. PMID:29447252

Dispersive micro solid phase extraction (DMSPE) using polymer anion exchange (PAX) as the sorbent followed by UPLC-MS/MS for the rapid determination of four bisphenols in commercial edible oils.

PubMed

Xian, Yanping; Wu, Yuluan; Dong, Hao; Guo, Xindong; Wang, Bin; Wang, Li

2017-09-29

The present work presents a novel and rapid analytical method for the simultaneous analysis of bisphenol A (BPA), bisphenol B (BPB), bisphenol F (BPF) and bisphenol S (BPS) in edible oil based on dispersive micro solid phase extraction (DMSPE) for the first time followed by isotope dilution-ultra high performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). The edible oil sample was dispersed by n-hexane and extracted with ammoniated methanol-water solution. Then the target analytes were dispersedly absorbed using the polymer anion exchange (PAX) as the sorbent and eluted by acidic methanol. After that, four bisphenols were separated on a C18 column by gradient elution with methanol and 0.05% ammonium hydroxide in water as mobile phase, detected by MS/MS under multiple reactions monitoring (MRM) mode and quantified by internal standard method. The PAX amounts, adsorption time, concentrations of formic acid in the elution solvent and volume of elution solvent for the DMSPE technique were optimized. The limit of detection and quantitation (LOD and LOQ), matrix effect, recovery and precision of the developed method were investigated. Results indicated that BPS and the rest three bisphenols displayed excellent linearity in the concentration ranges of 0.1-50μg/L and 0.5-250μg/L, respectively, with correlation coefficients (R 2 ) all larger than 0.998. Achieved MLODs (S/N=3) varied between 0.1-0.4μg/kg for all bisphenols. The mean recoveries at three spiked levels in edible oil were in the range of 87.3-108%. Intra-day precision (n=6) and inter-day precision (n=5) were <9% and <11%, respectively. This method is of rapid-and-simple pretreatment, accurate and sensitive, and suitable for the simultaneous determination of bisphenols in edible oil. Copyright © 2017. Published by Elsevier B.V.

Membrane current of retinal rods of Caudiverbera caudiverbera (Amphibia: Leptodactylidae): dark noise, spectral and absolute light sensitivity.

PubMed

Palma, F; Roncagliolo, P; Bacigalupo, J; Palacios, A G

2001-01-01

We investigated the photocurrents from isolated rods of the South American anuran, Caudiverbera caudiverbera. Rod outer segments were on average 66.4 +/- 11.2 microm (mean +/- S.D., n = 104) in length and 6.6 +/- 0.9 microm (mean +/- S.D.) in diameter: 40 +/- 22 photoisomerizations (mean +/- S.D., range 10-99, n = 16) were required for eliciting a half-saturating photocurrent response. The time-to-peak was 911 +/- 217 ms (mean +/- S.D., n = 14, 20 degrees C) in the linear range of the response and the integration time of the current response was 1744 +/- 451 ms (mean +/- S.D., n = 14). The time-to-peak appears to be slower and the integration time shorter in Caudiverbera than in Ambystoma tigrinum, Rana pipiens or Xenopus laevis rods under similar experimental conditions. The a-band of rod spectral sensitivity has a lambda(max) at 520 +/- 2.1 nm (mean +/- S.D., range 516-525 nm, n = 24) and the bandwidth fits a porphyropsin visual pigment. The single-event response amplitude ranges from 0.31-0.51 pA, depending on the calculation method. The intrinsic dark current (variance at dark minus variance under bright light) was 0.045 +/- 0.040 pA2 (mean +/- S.D., n = 24). Our results support the presence of a dark-noise component below 1 Hz, with kinetics similar to the single-photon evoked response and a rate of 0.006 events s(-1) (n = 9).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gundlach-Graham, Alexander W.; Dennis, Elise; Ray, Steven J.

Here we describe the first combination of a Distance-of-Flight Mass Spectrometry (DOFMS) instrument and an inductively coupled plasma (ICP) ion source. DOFMS is a velocity-based MS technique in which ions of a range of mass-to-charge (m/z) values are detected simultaneously along the length of a spatially selective detector. As a relative of time-of-flight (TOF) MS, DOFMS leverages benefits fromboth TOFMS and spatially dispersive MS. The simultaneous detection of groups of m/z values improves dynamic range by spreading ion signal across many detector elements and reduces correlated noise by signal ratioing. To ascertain the performance characteristics of the ICP-DOFMS instrument, wemore » have employed a microchannel-plate/phosphor detection assembly with a scientific CCD to capture images of the phosphor plate. With this simple (and commercially available) detection scheme, elemental detection limits from 2–30 ng L*1 and a linear dynamic range of 5 orders of magnitude (10–106 ng L1) have been demonstrated. Additionally, a competitive isotope-ratio precision of 0.1% RSD has been achieved with only a 6 s signal integration period. In addition to first figures of merit, this paper outlines technical considerations for the design of the ICP-DOFMS.« less

Methods for simultaneous detection of the cyanotoxins BMAA, DABA, and anatoxin-a in environmental samples.

PubMed

Al-Sammak, Maitham Ahmed; Hoagland, Kyle D; Snow, Daniel D; Cassada, David

2013-12-15

Blue-green algae, also known as cyanobacteria, can produce several different groups of toxins in the environment including hepatotoxins (microcystins), neurotoxic non-protein amino acids β-methylamino-l-alanine (BMAA), and 2,4-diaminobutyric (DABA), as well as the bicyclic amine alkaloid anatoxin-a. Few studies have addressed the methods necessary for an accurate determination of cyanotoxins in environmental samples, and none have been published that can detect these cyanotoxins together in a single sample. Cyanotoxins occur in a wide range of environmental samples including water, fish, and aquatic plant samples. Using polymeric cation exchange solid phase extraction (SPE) coupled with liquid chromatography and fluorescence detection (HPLC/FD), and liquid chromatography ion trap tandem mass spectrometry (LC/MS/MS), these compounds can for the first time be simultaneously quantified in a variety of environmental sample types. The extraction method for biological samples can distinguish bound and free cyanotoxins. Detection limits for water ranged from 5 to 7 μg/L using HPLC/FD, while detection limits for and LC/MS were in the range of 0.8-3.2 μg/L. Copyright © 2013 Elsevier Ltd. All rights reserved.

Electric Propulsion Options for 10 kW Class Earth-Space Missions

NASA Technical Reports Server (NTRS)

Patterson, M. J.; Curran, Francis M.

1989-01-01

Five and 10 kW ion and arcjet propulsion system options for a near-term space demonstration experiment were evaluated. Analyses were conducted to determine first-order propulsion system performance and system component mass estimates. Overall mission performance of the electric propulsion systems was quantified in terms of the maximum thrusting time, total impulse, and velocity increment capability available when integrated onto a generic spacecraft under fixed mission model assumptions. Maximum available thrusting times for the ion-propelled spacecraft options, launched on a DELTA 2 6920 vehicle, range from approximately 8,600 hours for a 4-engine 10 kW system to more than 29,600 hours for a single-engine 5 kW system. Maximum total impulse values and maximum delta-v's range from 1.2x10 (exp 7) to 2.1x10 (exp 7) N-s, and 3550 to 6200 m/s, respectively. Maximum available thrusting times for the arcjet propelled spacecraft launched on the DELTA 2 6920 vehicle range from approximately 528 hours for the 6-engine 10 kW hydrazine system to 2328 hours for the single-engine 5 kW system. Maximum total impulse values and maximum delta-v's range from 2.2x10 (exp 6) to 3.6x10 (exp 6) N-s, and approximately 662 to 1072 m/s, respectively.

Gas and particulate phase products from the ozonolysis of acenaphthylene

NASA Astrophysics Data System (ADS)

Riva, Matthieu; Healy, Robert M.; Tomaz, Sophie; Flaud, Pierre-Marie; Perraudin, Emilie; Wenger, John C.; Villenave, Eric

2016-10-01

Polycyclic aromatic hydrocarbons (PAHs) are recognized as important secondary organic aerosol (SOA) precursors in the urban atmosphere. In this work, the gas-phase ozonolysis of acenaphthylene was investigated in an atmospheric simulation chamber using a proton transfer reaction time-of-flight-mass spectrometer (PTR-TOF-MS) and an aerosol time-of-flight-mass spectrometer (ATOFMS) for on-line characterization of the oxidation products in the gas and particle phases, respectively. SOA samples were also collected on filters and analyzed by ultra performance liquid chromatography/electrospray ionization high-resolution quadrupole time-of-flight mass spectrometry (UPLC/ESI-HR-QTOFMS) and gas chromatography/electron impact ionization-mass spectrometry (GC/EI-MS). The major gas-phase products included a range of oxygenated naphthalene derivatives such as 1,8-naphthalic anhydride, naphthalene 1,8-dicarbaldehyde and naphthaldehyde, as well as a secondary ozonide. Possible reaction mechanisms are proposed for the formation of these products and favoured pathways have been suggested. Many of these products were also found in the particle phase along with a range of oligomeric compounds. The same range of gas and particle phase products was observed in the presence and absence of excess cyclohexane, an OH scavenger, indicating that OH radical production from the ozonolysis of acenaphthylene is negligible. SOA yields in the range 23-37% were determined and indicate that acenaphthylene ozonolysis may contribute to part of the SOA observed in urban areas.

A novel sampling method for identification of endogenous skin surface compounds by use of DART-MS and MALDI-MS.

PubMed

Mess, Aylin; Enthaler, Bernd; Fischer, Markus; Rapp, Claudius; Pruns, Julia K; Vietzke, Jens-Peter

2013-01-15

Identification of endogenous skin surface compounds is an intriguing challenge in comparative skin investigations. Notably, this short communication is focused on the analysis of small molecules, e.g. natural moisturizing factor (NMF) components and lipids, using a novel sampling method with DIP-it samplers for non-invasive examination of the human skin surface. As a result, extraction of analytes directly from the skin surface by use of various solvents can be replaced with the mentioned procedure. Screening of measureable compounds is achieved by direct analysis in real time mass spectrometry (DART-MS) without further sample preparation. Results are supplemented by dissolving analytes from the DIP-it samplers by use of different solvents, and subsequent matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) measurements. An interesting comparison of the mentioned MS techniques for determination of skin surface compounds in the mass range of 50-1000 Da is presented. Copyright © 2012 Elsevier B.V. All rights reserved.

Rosmarinus Officinalis Leaves as a Natural Source of Bioactive Compounds

PubMed Central

Borrás-Linares, Isabel; Stojanović, Zorica; Quirantes-Piné, Rosa; Arráez-Román, David; Švarc-Gajić, Jaroslava; Fernández-Gutiérrez, Alberto; Segura-Carretero, Antonio

2014-01-01

In an extensive search for bioactive compounds from plant sources, the composition of different extracts of rosemary leaves collected from different geographical zones of Serbia was studied. The qualitative and quantitative characterization of 20 rosemary (Rosmarinus officinalis) samples, obtained by microwave-assisted extraction (MAE), was determined by high performance liquid chromatography coupled to electrospray quadrupole-time of flight mass spectrometry (HPLC–ESI-QTOF-MS). The high mass accuracy and true isotopic pattern in both MS and MS/MS spectra provided by the QTOF-MS analyzer enabled the characterization of a wide range of phenolic compounds in the extracts, including flavonoids, phenolic diterpenes and abietan-type triterpenoids, among others. According to the data compiled, rosemary samples from Sokobanja presented the highest levels in flavonoids and other compounds such as carnosol, rosmaridiphenol, rosmadial, rosmarinic acid, and carnosic acid. On the other hand, higher contents in triterpenes were found in the extracts of rosemary from Gložan (Vojvodina). PMID:25391044

DIGE Analysis Software and Protein Identification Approaches.

PubMed

Hmmier, Abduladim; Dowling, Paul

2018-01-01

DIGE is a high-resolution two-dimensional gel electrophoresis method, with excellent dynamic range obtained by fluorescent tag labeling of protein samples. Scanned images of DIGE gels show thousands of protein spots, each spot representing a single or a group of protein isoforms. By using commercially available software, each protein spot is defined by an outline, which is digitized and correlated with the quantity of proteins present in each spot. Software packages include DeCyder, SameSpots, and Dymension 3. In addition, proteins of interest can be excised from post-stained gels and identified with conventional mass spectrometry techniques. High-throughput mass spectrometry is performed using sophisticated instrumentation including matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF), MALDI-TOF/TOF, and liquid chromatography tandem mass spectrometry (LC-MS/MS). Tandem MS (MALDI-TOF/TOF or LC-MS/MS), analyzes fragmented peptides, resulting in amino acid sequence information, especially useful when protein spots are low abundant or where a mixture of proteins is present.

Certification of NIST standard reference material 2389a, amino acids in 0.1 mol/L HCl--quantification by ID LC-MS/MS.

PubMed

Lowenthal, Mark S; Yen, James; Bunk, David M; Phinney, Karen W

2010-05-01

An isotope-dilution liquid chromatography-tandem mass spectrometry (ID LC-MS/MS) measurement procedure was developed to accurately quantify amino acid concentrations in National Institute of Standards and Technology (NIST) Standard Reference Material (SRM) 2389a-amino acids in 0.1 mol/L hydrochloric acid. Seventeen amino acids were quantified using selected reaction monitoring on a triple quadrupole mass spectrometer. LC-MS/MS results were compared to gravimetric measurements from the preparation of SRM 2389a-a reference material developed at NIST and intended for use in intra-laboratory calibrations and quality control. Quantitative mass spectrometry results and gravimetric values were statistically combined into NIST-certified mass fraction values with associated uncertainty estimates. Coefficients of variation (CV) for the repeatability of the LC-MS/MS measurements among amino acids ranged from 0.33% to 2.7% with an average CV of 1.2%. Average relative expanded uncertainty of the certified values including Types A and B uncertainties was 3.5%. Mean accuracy of the LC-MS/MS measurements with gravimetric preparation values agreed to within |1.1|% for all amino acids. NIST SRM 2389a will be available for characterization of routine methods for amino acid analysis and serves as a standard for higher-order measurement traceability. This is the first time an ID LC-MS/MS methodology has been applied for quantifying amino acids in a NIST SRM material.

Cobalt complexes as internal standards for capillary zone electrophoresis-mass spectrometry studies in biological inorganic chemistry.

PubMed

Holtkamp, Hannah U; Morrow, Stuart J; Kubanik, Mario; Hartinger, Christian G

2017-07-01

Run-by-run variations are very common in capillary electrophoretic (CE) separations and cause imprecision in both the migration times and the peak areas. This makes peak and kinetic trend identification difficult and error prone. With the aim to identify suitable standards for CE separations which are compatible with the common detectors UV, ESI-MS, and ICP-MS, the Co III complexes [Co(en) 3 ]Cl 3 , [Co(acac) 3 ] and K[Co(EDTA)] were evaluated as internal standards in the reaction of the anticancer drug cisplatin and guanosine 5'-monophosphate as an example of a classical biological inorganic chemistry experiment. These Co III chelate complexes were considered for their stability, accessibility, and the low detection limit for Co in ICP-MS. Furthermore, the Co III complexes are positively and negatively charged as well as neutral, allowing the detection in different areas of the electropherograms. The background electrolytes were chosen to cover a wide pH range. The compatibility to the separation conditions was dependent on the ligands attached to the Co III centers, with only the acetylacetonato (acac) complex being applicable in the pH range 2.8-9.0. Furthermore, because of being charge neutral, this compound could be used as an electroosmotic flow (EOF) marker. In general, employing Co complexes resulted in improved data sets, particularly with regard to the migration times and peak areas, which resulted, for example, in higher linear ranges for the quantification of cisplatin.

An algorithm to correct saturated mass spectrometry ion abundances for enhanced quantitation and mass accuracy in omic studies

DOE PAGES

Bilbao, Aivett; Gibbons, Bryson C.; Slysz, Gordon W.; ...

2017-11-06

We present that the mass accuracy and peak intensity of ions detected by mass spectrometry (MS) measurements are essential to facilitate compound identification and quantitation. However, high concentration species can yield erroneous results if their ion intensities reach beyond the limits of the detection system, leading to distorted and non-ideal detector response (e.g. saturation), and largely precluding the calculation of accurate m/z and intensity values. Here we present an open source computational method to correct peaks above a defined intensity (saturated) threshold determined by the MS instrumentation such as the analog-to-digital converters or time-to-digital converters used in conjunction with time-of-flightmore » MS. Here, in this method, the isotopic envelope for each observed ion above the saturation threshold is compared to its expected theoretical isotopic distribution. The most intense isotopic peak for which saturation does not occur is then utilized to re-calculate the precursor m/z and correct the intensity, resulting in both higher mass accuracy and greater dynamic range. The benefits of this approach were evaluated with proteomic and lipidomic datasets of varying complexities. After correcting the high concentration species, reduced mass errors and enhanced dynamic range were observed for both simple and complex omic samples. Specifically, the mass error dropped by more than 50% in most cases for highly saturated species and dynamic range increased by 1–2 orders of magnitude for peptides in a blood serum sample.« less

An algorithm to correct saturated mass spectrometry ion abundances for enhanced quantitation and mass accuracy in omic studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bilbao, Aivett; Gibbons, Bryson C.; Slysz, Gordon W.

The mass accuracy and peak intensity of ions detected by mass spectrometry (MS) measurements are essential to facilitate compound identification and quantitation. However, high concentration species can easily cause problems if their ion intensities reach beyond the limits of the detection system, leading to distorted and non-ideal detector response (e.g. saturation), and largely precluding the calculation of accurate m/z and intensity values. Here we present an open source computational method to correct peaks above a defined intensity (saturated) threshold determined by the MS instrumentation such as the analog-to-digital converters or time-to-digital converters used in conjunction with time-of-flight MS. In thismore » method, the isotopic envelope for each observed ion above the saturation threshold is compared to its expected theoretical isotopic distribution. The most intense isotopic peak for which saturation does not occur is then utilized to re-calculate the precursor m/z and correct the intensity, resulting in both higher mass accuracy and greater dynamic range. The benefits of this approach were evaluated with proteomic and lipidomic datasets of varying complexities. After correcting the high concentration species, reduced mass errors and enhanced dynamic range were observed for both simple and complex omic samples. Specifically, the mass error dropped by more than 50% in most cases with highly saturated species and dynamic range increased by 1-2 orders of magnitude for peptides in a blood serum sample.« less

An algorithm to correct saturated mass spectrometry ion abundances for enhanced quantitation and mass accuracy in omic studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bilbao, Aivett; Gibbons, Bryson C.; Slysz, Gordon W.

We present that the mass accuracy and peak intensity of ions detected by mass spectrometry (MS) measurements are essential to facilitate compound identification and quantitation. However, high concentration species can yield erroneous results if their ion intensities reach beyond the limits of the detection system, leading to distorted and non-ideal detector response (e.g. saturation), and largely precluding the calculation of accurate m/z and intensity values. Here we present an open source computational method to correct peaks above a defined intensity (saturated) threshold determined by the MS instrumentation such as the analog-to-digital converters or time-to-digital converters used in conjunction with time-of-flightmore » MS. Here, in this method, the isotopic envelope for each observed ion above the saturation threshold is compared to its expected theoretical isotopic distribution. The most intense isotopic peak for which saturation does not occur is then utilized to re-calculate the precursor m/z and correct the intensity, resulting in both higher mass accuracy and greater dynamic range. The benefits of this approach were evaluated with proteomic and lipidomic datasets of varying complexities. After correcting the high concentration species, reduced mass errors and enhanced dynamic range were observed for both simple and complex omic samples. Specifically, the mass error dropped by more than 50% in most cases for highly saturated species and dynamic range increased by 1–2 orders of magnitude for peptides in a blood serum sample.« less

Comparison of two methods for the detection of oligoclonal bands in a large number of clinically isolated syndrome and multiple sclerosis patients.

PubMed

Andlovic, Aljoša; Babič, Maša; Accetto, Slavko; Rot, Uroš

2012-07-01

A novel oligoclonal band (OB) assay which consists of isoelectric focusing (IEF) and IgG immunodetection by alkaline phosphatase-labeled anti IgG antibody was reported to be very sensitive. It also accurately predicted conversion to MS in patients with CIS. The aim of our study was to compare sensitivity of a novel and the standard procedure with peroxidase immunodetection in a large number of CIS and MS patients. OB were determined in serum and CSF samples in 161 patients (104 females), 47 with CIS and 114 with MS with median age 38 years (range 19-68) using both methods. Eighty-three percent of patients had CSF OB with the standard and 89% with the novel method. Median number of OB was 5 (range 0-17) with the peroxidase and 8 (range 0-18) with the alkaline phosphatase method; p = 0.001. Twenty-one percent of patients had ≥ 10 OB with the standard and 37% with the novel method of the detection; p = 0.021. Subjective impression of band clarity showed that 20% of patients had sharper and stronger bands when the peroxidase and 65% when the alkaline phosphatase method was used; p<0.0001. The alkaline phosphatase method is more sensitive than the peroxidase method and at the same time cheaper, easy to perform and less time consuming. Copyright © 2012 Elsevier B.V. All rights reserved.

Dynamics and heterogeneity of brain damage in multiple sclerosis

PubMed Central

Martinez-Lapiscina, Elena H.; Andorra, Magi; Olsson, Tomas; Martin, Roland; Paul, Friedemann; Tegnér, Jesper

2017-01-01

Multiple Sclerosis (MS) is an autoimmune disease driving inflammatory and degenerative processes that damage the central nervous system (CNS). However, it is not well understood how these events interact and evolve to evoke such a highly dynamic and heterogeneous disease. We established a hypothesis whereby the variability in the course of MS is driven by the very same pathogenic mechanisms responsible for the disease, the autoimmune attack on the CNS that leads to chronic inflammation, neuroaxonal degeneration and remyelination. We propose that each of these processes acts more or less severely and at different times in each of the clinical subgroups. To test this hypothesis, we developed a mathematical model that was constrained by experimental data (the expanded disability status scale [EDSS] time series) obtained from a retrospective longitudinal cohort of 66 MS patients with a long-term follow-up (up to 20 years). Moreover, we validated this model in a second prospective cohort of 120 MS patients with a three-year follow-up, for which EDSS data and brain volume time series were available. The clinical heterogeneity in the datasets was reduced by grouping the EDSS time series using an unsupervised clustering analysis. We found that by adjusting certain parameters, albeit within their biological range, the mathematical model reproduced the different disease courses, supporting the dynamic CNS damage hypothesis to explain MS heterogeneity. Our analysis suggests that the irreversible axon degeneration produced in the early stages of progressive MS is mainly due to the higher rate of myelinated axon degeneration, coupled to the lower capacity for remyelination. However, and in agreement with recent pathological studies, degeneration of chronically demyelinated axons is not a key feature that distinguishes this phenotype. Moreover, the model reveals that lower rates of axon degeneration and more rapid remyelination make relapsing MS more resilient than the progressive subtype. Therefore, our results support the hypothesis of a common pathogenesis for the different MS subtypes, even in the presence of genetic and environmental heterogeneity. Hence, MS can be considered as a single disease in which specific dynamics can provoke a variety of clinical outcomes in different patient groups. These results have important implications for the design of therapeutic interventions for MS at different stages of the disease. PMID:29073203

Dynamics and heterogeneity of brain damage in multiple sclerosis.

PubMed

Kotelnikova, Ekaterina; Kiani, Narsis A; Abad, Elena; Martinez-Lapiscina, Elena H; Andorra, Magi; Zubizarreta, Irati; Pulido-Valdeolivas, Irene; Pertsovskaya, Inna; Alexopoulos, Leonidas G; Olsson, Tomas; Martin, Roland; Paul, Friedemann; Tegnér, Jesper; Garcia-Ojalvo, Jordi; Villoslada, Pablo

2017-10-01

Multiple Sclerosis (MS) is an autoimmune disease driving inflammatory and degenerative processes that damage the central nervous system (CNS). However, it is not well understood how these events interact and evolve to evoke such a highly dynamic and heterogeneous disease. We established a hypothesis whereby the variability in the course of MS is driven by the very same pathogenic mechanisms responsible for the disease, the autoimmune attack on the CNS that leads to chronic inflammation, neuroaxonal degeneration and remyelination. We propose that each of these processes acts more or less severely and at different times in each of the clinical subgroups. To test this hypothesis, we developed a mathematical model that was constrained by experimental data (the expanded disability status scale [EDSS] time series) obtained from a retrospective longitudinal cohort of 66 MS patients with a long-term follow-up (up to 20 years). Moreover, we validated this model in a second prospective cohort of 120 MS patients with a three-year follow-up, for which EDSS data and brain volume time series were available. The clinical heterogeneity in the datasets was reduced by grouping the EDSS time series using an unsupervised clustering analysis. We found that by adjusting certain parameters, albeit within their biological range, the mathematical model reproduced the different disease courses, supporting the dynamic CNS damage hypothesis to explain MS heterogeneity. Our analysis suggests that the irreversible axon degeneration produced in the early stages of progressive MS is mainly due to the higher rate of myelinated axon degeneration, coupled to the lower capacity for remyelination. However, and in agreement with recent pathological studies, degeneration of chronically demyelinated axons is not a key feature that distinguishes this phenotype. Moreover, the model reveals that lower rates of axon degeneration and more rapid remyelination make relapsing MS more resilient than the progressive subtype. Therefore, our results support the hypothesis of a common pathogenesis for the different MS subtypes, even in the presence of genetic and environmental heterogeneity. Hence, MS can be considered as a single disease in which specific dynamics can provoke a variety of clinical outcomes in different patient groups. These results have important implications for the design of therapeutic interventions for MS at different stages of the disease.

Simultaneous determination of antidementia drugs in human plasma: procedure transfer from HPLC-MS to UPLC-MS/MS.

PubMed

Noetzli, Muriel; Ansermot, Nicolas; Dobrinas, Maria; Eap, Chin B

2012-05-01

A previously developed high performance liquid chromatography mass spectrometry (HPLC-MS) procedure for the simultaneous determination of antidementia drugs, including donepezil, galantamine, memantine, rivastigmine and its metabolite NAP 226-90, was transferred to an ultra performance liquid chromatography system coupled to a tandem mass spectrometer (UPLC-MS/MS). The drugs and their internal standards ([(2)H(7)]-donepezil, [(13)C,(2)H(3)]-galantamine, [(13)C(2),(2)H(6)]-memantine, [(2)H(6)]-rivastigmine) were extracted from 250 μL human plasma by protein precipitation with acetonitrile. Chromatographic separation was achieved on a reverse phase column (BEH C18 2.1 mm × 50 mm; 1.7 μm) with a gradient elution of an ammonium acetate buffer at pH 9.3 and acetonitrile at a flow rate of 0.4 mL/min and an overall run time of 4.5 min. The analytes were detected on a tandem quadrupole mass spectrometer operated in positive electrospray ionization mode, and quantification was performed using multiple reaction monitoring. The method was validated according to the recommendations of international guidelines over a calibration range of 1-300 ng/mL for donepezil, galantamine and memantine, and 0.2-50 ng/mL for rivastimgine and NAP 226-90. The trueness (86-108%), repeatability (0.8-8.3%), intermediate precision (2.3-10.9%) and selectivity of the method were found to be satisfactory. Matrix effects variability was inferior to 15% for the analytes and inferior to 5% after correction by internal standards. A method comparison was performed with patients' samples showing similar results between the HPLC-MS and UPLC-MS/MS procedures. Thus, this validated UPLC-MS/MS method allows to reduce the required amount of plasma, to use a simplified sample preparation, and to obtain a higher sensitivity and specificity with a much shortened run-time. Copyright © 2012 Elsevier B.V. All rights reserved.

LORETA EEG phase reset of the default mode network

PubMed Central

Thatcher, Robert W.; North, Duane M.; Biver, Carl J.

2014-01-01

Objectives: The purpose of this study was to explore phase reset of 3-dimensional current sources in Brodmann areas located in the human default mode network (DMN) using Low Resolution Electromagnetic Tomography (LORETA) of the human electroencephalogram (EEG). Methods: The EEG was recorded from 19 scalp locations from 70 healthy normal subjects ranging in age from 13 to 20 years. A time point by time point computation of LORETA current sources were computed for 14 Brodmann areas comprising the DMN in the delta frequency band. The Hilbert transform of the LORETA time series was used to compute the instantaneous phase differences between all pairs of Brodmann areas. Phase shift and lock durations were calculated based on the 1st and 2nd derivatives of the time series of phase differences. Results: Phase shift duration exhibited three discrete modes at approximately: (1) 25 ms, (2) 50 ms, and (3) 65 ms. Phase lock duration present primarily at: (1) 300–350 ms and (2) 350–450 ms. Phase shift and lock durations were inversely related and exhibited an exponential change with distance between Brodmann areas. Conclusions: The results are explained by local neural packing density of network hubs and an exponential decrease in connections with distance from a hub. The results are consistent with a discrete temporal model of brain function where anatomical hubs behave like a “shutter” that opens and closes at specific durations as nodes of a network giving rise to temporarily phase locked clusters of neurons for specific durations. PMID:25100976

TDM interrogation of intensity-modulated USFBGs network based on multichannel lasers.

PubMed

Rohollahnejad, Jalal; Xia, Li; Cheng, Rui; Ran, Yanli; Rahubadde, Udaya; Zhou, Jiaao; Zhu, Lin

2017-01-23

We report a large-scale multi-channel fiber sensing network, where ultra-short FBGs (USFBGs) instead of conventional narrow-band ultra-weak FBGs are used as the sensors. In the time division multiplexing scheme of the network, each grating response is resolved as three adjacent discrete peaks. The central wavelengths of USFBGs are tracked with the differential detection, which is achieved by calculating the peak-to-peak ratio of two maximum peaks. Compared with previous large-scale hybrid multiplexing sensing networks (e.g., WDM/TDM) which typically have relatively low interrogation speed and very high complexity, the proposed system can achieve interrogation of all channel sensors through very fast and simple intensity measurements with a broad dynamic range. A proof-of-concept experiment with twenty USFBGs, at two wavelength channels, was performed and a fast static strain measurements were demonstrated, with a high average sensitivity of ~0.54dB/µƐ and wide dynamic range of over ~3000µƐ. The channel to channel switching time was 10ms and total network interrogation time was 50ms.

Assessment of four protocols for rapid bacterial identification from positive blood culture pellets by matrix-assisted laser desorption ionization-time of flight mass spectrometry (Vitek® MS).

PubMed

Thomin, Jean; Aubin, Guillaume Ghislain; Foubert, Fabrice; Corvec, Stéphane

2015-08-01

In this study, we developed and compared four protocols to prepare a bacterial pellet from 944 positive blood cultures for direct MALDI-TOF mass spectrometry Vitek® MS analysis. Protocol 4, tested on 200 monomicrobial samples, allowed 83% of bacterial identification. This easy, fast, cheap and accurate method is promising in daily practice, especially to limit broad range antibiotic treatment. Copyright © 2015 Elsevier B.V. All rights reserved.

Methods of Analysis - Determination of Pyrethroid Insecticides in Water and Sediment Using Gas Chromatography/Mass Spectrometry

USGS Publications Warehouse

Hladik, Michelle; Smalling, Kelly L.; Kuivila, Kathryn

2009-01-01

A method for the determination of 14 pyrethroid insecticides in environmental water and sediment samples is described. The method was developed by the U.S. Geological Survey in response to increasing concern over the effects of pyrethroids on aquatic organisms. The pyrethroids included in this method are ones that are applied to many agricultural and urban areas. Filtered water samples are extracted for pyrethroids using solid-phase extraction (SPE) with no additional cleanup steps. Sediment and soil samples are extracted using a microwave-assisted extraction system, and the pyrethroids of interest are separated from co-extracted matrix interferences by passing the extracts through stacked graphitized carbon and alumina SPE cartridges, along with the use of high-performance liquid chromatography and gel-permeation chromatography (HPLC/GPC). Quantification of the pyrethroids from the extracted water and sediment samples is done using gas chromatography with mass spectrometry (GC/MS) or gas chromatography with tandem mass spectrometry (GC/MS/MS). Recoveries in test water samples fortified at 10 ng/L ranged from 83 to 107 percent, and recoveries in test sediment samples fortified at 10 ug/kg ranged from 82 to 101 percent; relative standard deviations ranged from 5 to 9 percent in the water samples and 3 to 9 percent in the sediment samples. Method detection limits (MDLs), calculated using U.S. Environmental Protection Agency procedures (40 CFR 136, Appendix B), in water ranged from 2.0 to 6.0 ng/L using GC/MS and 0.5 to 1.0 ng/L using GC/MS/MS. For sediment, the MDLs ranged from 1.0 to 2.6 ug/kg dry weight using GC/MS and 0.2 to 0.5 ug/kg dry weight using GC/MS/MS. The matrix-spike recoveries for each compound, when averaged for 12 environmental water samples, ranged from 84 to 96 percent, and when averaged for 27 environmental sediment samples, ranged from 88 to 100 percent.

Metabolic Profiling of Hoodia, Chamomile, Terminalia Species and Evaluation of Commercial Preparations Using Ultrahigh-Performance Liquid Chromatography Quadrupole-Time-of-Flight Mass Spectrometry.

PubMed

Avula, Bharathi; Wang, Yan-Hong; Isaac, Giorgis; Yuk, Jimmy; Wrona, Mark; Yu, Kate; Khan, Ikhlas A

2017-11-01

Ultrahigh-performance liquid chromatography quadrupole-time-of-flight mass spectrometry (UHPLC-QToF-MS) profiling was used for the identification of marker compounds and generation of metabolic patterns that could be interrogated using chemometric modeling software. UHPLC-QToF-MS was used to generate comprehensive fingerprints of three botanicals ( Hoodia, Terminalia , and chamomile), each having different classes of compounds. Detection of a broad range of ions was carried out in full scan mode in both positive and negative modes over the range m/z 100-1700 using high-resolution mass spectrometry. Multivariate statistical analysis was used to extract relevant chemical information from the data to easily differentiate between Terminalia species, chamomile varieties, and quality control of Hoodia products. Using nontargeted analysis, identification of 37 compounds contributed to the differences between Terminalia species, 26 flavonoids were identified to show the differences between German and Roman chamomile, and 43 pregnane glycosides were identified from Hoodia gordonii samples. The UHPLC-QToF-MS-based chemical fingerprinting with principal component analysis was able to correctly distinguish botanicals and their commercial products. This work can be used as a basis to assure the quality of botanicals and commercial products. Georg Thieme Verlag KG Stuttgart · New York.

Magnetic Levitation Force Measurement System at Any Low Temperatures From 20 K To 300 K

NASA Astrophysics Data System (ADS)

Celik, Sukru; Guner, S. Baris; Coskun, Elvan

2015-03-01

Most of the magnetic levitation force measurements in previous studies were performed at liquid nitrogen temperatures. For the levitation force of MgB2 and iron based superconducting samples, magnetic levitation force measurement system is needed. In this study, magnetic levitation force measurement system was designed. In this system, beside vertical force versus vertical motion, lateral and vertical force versus lateral motion measurements, the vertical force versus temperature at the fixed distance between permanent magnet PM - superconducting sample SS and the vertical force versus time measurements were performed at any temperatures from 20 K to 300 K. Thanks to these measurements, the temperature dependence, time dependence, and the distance (magnetic field) and temperature dependences of SS can be investigated. On the other hand, the magnetic stiffness MS measurements can be performed in this system. Using the measurement of MS at different temperature in the range, MS dependence on temperature can be investigated. These measurements at any temperatures in the range help to the superconductivity properties to be characterized. This work was supported by TUBTAK-the Scientific and technological research council of Turkey under project of MFAG - 110T622. This system was applied to the Turkish patent institute with the Application Number of 2013/13638 on 22/11/2013.

Cryogenic-cooled Tm:SBN tunable laser

NASA Astrophysics Data System (ADS)

Švejkar, Richard; Šulc, Jan; Němec, Michal; Jelínková, Helena; Doroshenko, Maxim E.; Papashvili, Alexander G.; Batygov, Sergei H.; Osiko, Vyacheslav V.

2017-12-01

In this work the temperature dependence of spectroscopic and laser properties of new ac- tive medium Tm:SBN (Strontium-Barium Niobate, SrxBa1-xNb2O6, x = 0.61). The tested sample of Tm:SBN (2 wt. % of Tm2O3) appropriate for generation of laser radiation at 1.88 μm had plan-parallel polished faces without anti-reflection (thickness 6.65 mm). During spectroscopy and laser experiments the Tm:SBN was at- tached to temperature-controlled copper holder and was placed in a vacuum chamber. The transmission and emission spectra of Tm:SBN and the fluorescence decay time were measured depending on temperature range 80 - 350 K. The fluorescence decay time was measured to be 3.5 ms and 2.8 ms at 80 and 350 K, respectively. Longitudinal excitation of Tm:SBN was carried out by a fibre-coupled laser diode (pulse duration 10 ms, rep- etition rate 10 Hz, pump wavelength 793 nm). The laser resonator was hemispherical, 146 mm long, with flat pumping mirror (HR @1.8 - 2.1 μm) and spherical output coupler (r = 150 mm, R = 97.5 % @1.8 - 2.1 μm). The Tm:SBN laser properties were investigated at temperature range 80 - 300 K. The highest slope efficiency with respect to absorbed pumped power was 3 % at 80 K. The maximum output peak amplitude power was 0.12 W at 80 K, i.e. 3.2 times higher than it was measured at 200 K. Tunability of laser wavelength at 80 K in the range of 1827 - 1962 nm was obtained by using SiO2 birefringent filter. At 300 K, wavelength tunability reached 1859 - 1970 nm. Thus, the new Tm:SBN crystal can be an useful laser material in the region of 2 μm.

Shoulder magnetic resonance imaging abnormalities, wheelchair propulsion, and gender.

PubMed

Boninger, Michael L; Dicianno, Brad E; Cooper, Rory A; Towers, Jeffrey D; Koontz, Alicia M; Souza, Aaron L

2003-11-01

To investigate the relationship between pushrim forces and the progression of shoulder injuries in manual wheelchair users. Longitudinal case series. Biomechanics laboratory and magnetic resonance imaging (MRI) facility at a Veterans Health Administration medical center and university hospital, respectively. Fourteen individuals with spinal cord injury (8 men, 6 women) who used manual wheelchairs. Subjects propelled their own wheelchairs on a dynamometer at 0.9 and 1.8m/s. Bilateral biomechanical data were obtained by using force and moment sensing pushrims at time 1. Bilateral shoulder MR images were also completed on 2 occasions, at time 1 and, approximately 2 years later, at time 2. The peak pushrim forces in a pushrim coordinate system were calculated, weight normalized and averaged over 5 strokes (presented as % body weight). MRI abnormalities were graded by using a summated scale. Differences between scores between times 1 and 2 were calculated. Subjects were divided into 2 groups based on change in MRI score. Seven subjects were in the group with worsening scores (MRI+; mean, 8.14 points; range, 5-16), and 7 were in the group with improving or unchanging scores (MRI-; mean, -1.00 point; range, -5 to 1). There was no significant difference between groups with respect to age, body mass index, or years from injury. There were significantly more women in the MRI+ group (6 women, 1 man) than in the MRI- group (7 men) (P=.001). The MRI+ group used significantly greater weight-normalized radial force, or force directed toward the axle at time 1, to propel their wheelchairs at each speed (P<.01): MRI+ at 0.9m/s (mean radial force +/- standard deviation, 5.2%+/-1.0%) and MRI- at 0.9m/s (mean radial force, 3.2%+/-1.7%) (P=.028); and MRI+ at 1.8m/s (mean radial force, 6.6%+/-1.2%) (P=.023) and MRI- at 1.8m/s (mean radial force, 4.1%+/-2.2%). In a separate analysis, women were found to propel with a significantly higher radial force. A logistic regression found a significant relationship between radial force at time 1 and increased risk of progression of MRI findings over time. Individuals who propel with a greater percentage of force directed toward the axle were at increased risk of progression of MRI findings over time. Most people in this group were women. Clinicians should instruct wheelchair users in effective propulsion techniques and should pay particular attention to women who use wheelchairs. Reducing forces during wheelchair propulsion may minimize the likelihood of developing shoulder injuries.

What triggers catch-up saccades during visual tracking?

PubMed

de Brouwer, Sophie; Yuksel, Demet; Blohm, Gunnar; Missal, Marcus; Lefèvre, Philippe

2002-03-01

When tracking moving visual stimuli, primates orient their visual axis by combining two kinds of eye movements, smooth pursuit and saccades, that have very different dynamics. Yet, the mechanisms that govern the decision to switch from one type of eye movement to the other are still poorly understood, even though they could bring a significant contribution to the understanding of how the CNS combines different kinds of control strategies to achieve a common motor and sensory goal. In this study, we investigated the oculomotor responses to a large range of different combinations of position error and velocity error during visual tracking of moving stimuli in humans. We found that the oculomotor system uses a prediction of the time at which the eye trajectory will cross the target, defined as the "eye crossing time" (T(XE)). The eye crossing time, which depends on both position error and velocity error, is the criterion used to switch between smooth and saccadic pursuit, i.e., to trigger catch-up saccades. On average, for T(XE) between 40 and 180 ms, no saccade is triggered and target tracking remains purely smooth. Conversely, when T(XE) becomes smaller than 40 ms or larger than 180 ms, a saccade is triggered after a short latency (around 125 ms).

LC-MS/MS method for the simultaneous determination of Lys-MCC-DM1, MCC-DM1 and DM1 as potential intracellular catabolites of the antibody-drug conjugate trastuzumab emtansine (T-DM1).

PubMed

Liu, Yazhong; Zhou, Fang; Sang, Hua; Ye, Hui; Chen, Qianying; Yao, Lan; Ni, Ping; Wang, Guangji; Zhang, Jingwei

2017-04-15

Lysine-MCC-DM1, MCC-DM1 and DM1 are potential catabolites of trastuzumab emtansine (T-DM1). A convenient liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated to detect these catabolites simultaneously in in vitro investigations for the first time. Protein precipitation was utilized to prepare the samples. Chromatographic separation was achieved on a Phenomenex Kinetex C18 column (100×2.1mm, 2.6μm) with mobile-phase gradient elution. The calibration curves of each analyte ranging from 1 to 100nM showed good linearity (r 2 >0.995). The method was validated successfully and applied to the intracellular catabolism and regulation of T-DM1. Copyright © 2017 Elsevier B.V. All rights reserved.

Integrated protein analysis platform based on column switch recycling size exclusion chromatography, microenzymatic reactor and microRPLC-ESI-MS/MS.

PubMed

Yuan, Huiming; Zhou, Yuan; Zhang, Lihua; Liang, Zhen; Zhang, Yukui

2009-10-30

An integrated platform with the combination of proteins and peptides separation was established via the unit of on-line proteins digestion, by which proteins were in sequence separated by column switch recycling size exclusion chromatography (csrSEC), on-line digested by an immobilized trypsin microreactor, trapped and desalted by two parallel C8 precolumns, separated by microRPLC with the linear gradient of organic modifier concentration, and identified by ESI-MS/MS. A 6-protein mixture, with Mr ranging from 10 kDa to 80 kDa, was used to evaluate the performance of the integrated platform, and all proteins were identified with sequence coverage over 5.67%. Our experimental results demonstrate that such an integrated platform is of advantages such as good time compatibility, high peak capacity, and facile automation, which might be a promising approach for proteome study.

Impact of Pharmaceutical Impurities in Ecstasy Tablets: Gas Chromatography-Mass Spectrometry Study

PubMed Central

Jalali, Amir; Hatamie, Amir; Saferpour, Tahere; Khajeamiri, Alireza; Safa, Tahere; Buazar, Foad

2016-01-01

In this study, a simple and reliable method by gas chromatograph–mass spectrometry (GC–MS) was developed for the fast and regular identification of 3, 4-MDMA impurities in ecstasy tablets. In so doing, 8 samples of impurities were extracted by diethyl ether under alkaline condition and then analyzed by GC–MS. The results revealed high MDMA levels ranging from 37.6% to 57.7%. The GC-MS method showed that unambiguous identification can be achieved for MDMA from 3, 4-methylenedioxyamphetamine (MDA), Amphetamine (AM), methamphetamine (MA) and ketamine (Keta) compounds, respectively. The experimental results indicated the acceptable time window without interfering peaks. It is found that GC-MS was provided a suitable and rapid identification approach for MDMA (Ecstacy) tablets, particularly in the Forensic labs. Consequently, the intense MDMA levels would support the police to develop a simple quantification of impurity in Ecstasy tablets. PMID:27610162

High precision mass measurements for wine metabolomics

NASA Astrophysics Data System (ADS)

Roullier-Gall, Chloé; Witting, Michael; Gougeon, Régis; Schmitt-Kopplin, Philippe

2014-11-01

An overview of the critical steps for the non-targeted Ultra-High Performance Liquid Chromatography coupled with Quadrupole Time-of-Flight Mass Spectrometry (UPLC-Q-ToF-MS) analysis of wine chemistry is given, ranging from the study design, data preprocessing and statistical analyses, to markers identification. UPLC-Q-ToF-MS data was enhanced by the alignment of exact mass data from FTICR-MS, and marker peaks were identified using UPLC-Q-ToF-MS². In combination with multivariate statistical tools and the annotation of peaks with metabolites from relevant databases, this analytical process provides a fine description of the chemical complexity of wines, as exemplified in the case of red (Pinot noir) and white (Chardonnay) wines from various geographic origins in Burgundy.

Decreased locomotor and investigatory exploration after denervation of catecholamine terminal fields in the forebrain of rats.

PubMed

Dubois, A B; Ogilvy, C S

1978-12-01

1. Pressures on the right and left sides of the tails of swimming bluefish were measured and found to have a range of +5.9 to -5.9 cm H2O. The pressures were resolved into their forward and lateral vectorial components of force to allow calculation of forward and lateral force and power at speeds ranging from 0.26 to 0.87 m/s. 2. The peak to peak changes in force of acceleration of the body, measured with a forward accelerometer averaged 209 g or 2.05 N at 0.48 m/s, and were compared with the maximum to minimum excursions of forward tail force averaging 201 g or 1.97 N at the same speed. The mean difference was 8 g, S.D. of the mean difference +/-29, SE. of mean difference +/-10 g. 3. Mean tail thrust was calculated as the time average of tail force in the forward direction. It averaged 65 g , or 0.64 N, at 0.48 m/s. The mean forward power was 0.34 N m/s at 0.48 m/s. The drag of the gauges and wires accounted for 10% of this figure. 4. The mean lateral power of the tail was 1.28 N m/s at a mean speed of 0.48 m/s. 5. The propulsive efficiency of the tail, calculated as the ratio of forward power to forward plus lateral power, was found to be 0.20 S.D.+/-0.04, S.E.+/-0.01 and was not related to speed. This suggests that 80% of the mechanical power of the tail was wasted. Turbulence in the water may have contributed to this large drag and low tail efficiency.

Characterization and quantitation of yohimbine and its analogs in botanicals and dietary supplements using LC/QTOF-MS and LC/QQQ-MS for determination of the presence of bark extract and yohimbine adulteration.

PubMed

Lucas, Derick; Neal-Kababick, James; Zweigenbaum, Jerry

2015-01-01

The compound yohimbine HCl has been restricted in Australia and categorized as a scheduled prescription drug in other parts of the world, including the United States where it is monographed as a drug in the U. S. Pharmacopeia. However, the bark of the yohimbe plant and its extract is considered a botanical that can be used as a dietary supplement in some parts of the world. For these reasons, methods to characterize the indole alkaloids of the bark and quantify yohimbine and its analogs are presented using accurate mass LC/quadrupole time-of-flight (QTOF)-MS and triple quadrupole LC/MS, respectively. Samples were extracted with a QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) method to characterize and quantify the indole alkaloids. With the LC/QTOF-MS in auto MS/MS mode the indole alkaloids were identified, and the isomeric response of each could be used to determine whether the actual bark or extract was in samples of dietary supplements and not adulteration with yohimbine HCl. Analogs were identified and include yohimbic acid, methyl yohimbine, and hydroxyl yohimbine. Many isomers of each were also detected, but identified only by the number of chromatographic peaks. Quantification of yohimbine and ajmalicine spiked extracts showed recoveries of 99 to 103% with RSD of 3.6% or lower and LODs of less than 100 ppt. Calibration of the two standards gave r(2) = 0.9999 in a range from 0.1 to 100 ppb. Dietary supplements quantified for these two compounds showed a range from not detected to 3x the amounts found in the bark.

A kinetic study of blinking responses in cats

PubMed Central

Trigo, José Alberto; Roa, Laura; Gruart, Agnès; Delgado-García, José María

2003-01-01

Reflexively evoked and eye-related eyelid responses were recorded using the search coil in a magnetic field technique in alert cats. The downward phase of a blink was a large (up to 21 deg), fast (up to 2000 deg s−1) eyelid displacement in the closing direction, with an almost fixed rise time duration (15-20 ms); its maximum velocity was achieved in ≈10 ms. Upward eyelid motion was separated into two phases. The first phase consisted of a fast eyelid displacement, with a short duration (≈30 ms) and a maximum velocity up to 900 deg s−1. The second phase had an exponential-like form, lasting for 200–400 ms, and a maximum velocity ranging between 30 and 250 deg s−1. Maximum blink velocity in the downward direction was linearly related to maximum velocity of the first upward phase. The first phase in the upward direction was never observed if the eyelid stayed closed for a long period (> 50 ms) or moved slowly in the closing direction before it started to open. In these two cases, the upswing motion of the blink reflex contained only the exponential-like movement characteristic of the second upward phase, and maximum velocity in the downward direction was not related to that of the eyelid upward displacement. Mean duration of eyelid downward saccades was ≈130 ms, and their peak velocities ranged between 50 and 440 ms. A physiological model is presented explaining the active and passive forces involved in both reflex and saccadic eyelid responses. A second-order system seems to be appropriate to describe the postulated biomechanical model. PMID:12665614

Slow Speed--Fast Motion: Time-Lapse Recordings in Physics Education

ERIC Educational Resources Information Center

Vollmer, Michael; Möllmann, Klaus-Peter

2018-01-01

Video analysis with a 30 Hz frame rate is the standard tool in physics education. The development of affordable high-speed-cameras has extended the capabilities of the tool for much smaller time scales to the 1 ms range, using frame rates of typically up to 1000 frames s[superscript -1], allowing us to study transient physics phenomena happening…

Time course of discrimination between emotional facial expressions: the role of visual saliency.

PubMed

Calvo, Manuel G; Nummenmaa, Lauri

2011-08-01

Saccadic and manual responses were used to investigate the speed of discrimination between happy and non-happy facial expressions in two-alternative-forced-choice tasks. The minimum latencies of correct saccadic responses indicated that the earliest time point at which discrimination occurred ranged between 200 and 280ms, depending on type of expression. Corresponding minimum latencies for manual responses ranged between 440 and 500ms. For both response modalities, visual saliency of the mouth region was a critical factor in facilitating discrimination: The more salient the mouth was in happy face targets in comparison with non-happy distracters, the faster discrimination was. Global image characteristics (e.g., luminance) and semantic factors (i.e., categorical similarity and affective valence of expression) made minor or no contribution to discrimination efficiency. This suggests that visual saliency of distinctive facial features, rather than the significance of expression, is used to make both early and later expression discrimination decisions. Copyright © 2011 Elsevier Ltd. All rights reserved.

Efficient Analysis of Mass Spectrometry Data Using the Isotope Wavelet

NASA Astrophysics Data System (ADS)

Hussong, Rene; Tholey, Andreas; Hildebrandt, Andreas

2007-09-01

Mass spectrometry (MS) has become today's de-facto standard for high-throughput analysis in proteomics research. Its applications range from toxicity analysis to MS-based diagnostics. Often, the time spent on the MS experiment itself is significantly less than the time necessary to interpret the measured signals, since the amount of data can easily exceed several gigabytes. In addition, automated analysis is hampered by baseline artifacts, chemical as well as electrical noise, and an irregular spacing of data points. Thus, filtering techniques originating from signal and image analysis are commonly employed to address these problems. Unfortunately, smoothing, base-line reduction, and in particular a resampling of data points can affect important characteristics of the experimental signal. To overcome these problems, we propose a new family of wavelet functions based on the isotope wavelet, which is hand-tailored for the analysis of mass spectrometry data. The resulting technique is theoretically well-founded and compares very well with standard peak picking tools, since it is highly robust against noise spoiling the data, but at the same time sufficiently sensitive to detect even low-abundant peptides.

Propulsion of the Water Flea, Daphnia magna: Experiments, Scaling, and Modelling

NASA Astrophysics Data System (ADS)

Skipper, A. N.; Murphy, D.; Webster, D. R.; Yen, J.

2016-02-01

The freshwater crustacean Daphnia magna is a widely studied zooplankton in relation to food webs, predator-prey interactions, and other biological/ecological considerations; however, their locomotion is poorly quantified and understood. These water fleas utilize a hop-and-sink mechanism that consists of making quick, impulsive jumps by beating their antennae to propel themselves forward ( 1 body length). The animals then sink for a period, during which they stretch out their antennae to increase drag and thereby reduce their sinking velocity. Time-resolved three-dimensional flow fields surrounding the animals were quantified with a unique infrared tomographic particle image velocity (tomo-PIV) system. Three-dimensional kinematics data were also extracted from the image sequences. In the current work, we compared body kinematics and flow disturbance among organisms of size in the range of 1.3 to 2.8 mm. The stroke cycle averaged 150 ms in duration, ranging from 100 to 180 ms; this period is generally evenly split between the power and recovery strokes. The range of peak hop velocity was 27.2 to 32.5 mm/s, and peak acceleration was in the range of 0.68 to 1.8 m/s2. The results showed a distinct relationship between peak hop speed (Vmax 14 BL/s) and body size; these data collapsed onto a single time-record curve during the power stroke when properly non-dimensionalized. The fluid flow induced by each antennae consisted of a viscous vortex ring that demonstrated a slow decay in the wake. The strength, size, and decay of the induced viscous vortex rings were compared as a function of organism size. Finally, the viscous vortex rings were analyzed in the context of a double Stokeslet model that consisted of two impulsively applied point forces separated by the animal width.

Determination of 48 fragrance allergens in toys using GC with ion trap MS/MS.

PubMed

Lv, Qing; Zhang, Qing; Li, Wentao; Li, Haiyu; Li, Pi; Ma, Qiang; Meng, Xianshuang; Qi, Meiling; Bai, Hua

2013-11-01

This paper presents a method for the simultaneous determination of 48 fragrance allergens in four types of toys (plastic toys, play clays, plush toys, and paper toys) based on GC with ion trap MS/MS. Compared with single-stage MS, MS/MS is superior in terms of the qualification and quantification of a large range of compounds in complicated matrices. Procedures for extraction and purification were optimized for each toy type. The method proved to be linear over a wide range of concentrations for all analytes with correlation coefficients between 0.9768 and 0.9999. Validation parameters, namely, LODs and LOQs, ranged from 0.005-5.0 and from 0.02-20 mg/kg, respectively. Average recoveries of target compounds (spiked at three concentration levels) were in the range of 79.5-109.1%. Intraday and interday repeatabilities of the proposed method varied from 0.7-10.5% and from 3.1-13.4%, respectively. The proposed method was used to monitor fragrance allergens in commercial toy products. Our findings indicate that this method is an accurate and effective technique for analyzing fragrance allergens in materials composed of complex components. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

STS-109 MS Linnehan with laser range finder on aft flight deck

NASA Image and Video Library

2002-03-02

STS109-E-5003 (3 March 2002) --- Astronaut Richard M. Linnehan, mission specialist, uses a laser ranging device designed to measure the range between two spacecraft. Linnehan positioned himself on the cabin's aft flight deck as the Space Shuttle Columbia approached the Hubble Space Telescope. A short time later, the STS-109 crew captured and latched down the giant telescope in the vehicle's cargo bay for several days of work on the Hubble. The image was recorded with a digital still camera.

STS-109 MS Linnehan with laser range finder on aft flight deck

NASA Image and Video Library

2002-03-02

STS109-E-5002 (3 March 2002) --- Astronaut Richard M. Linnehan, mission specialist, uses a laser ranging device designed to measure the range between two spacecraft. Linnehan positioned himself on the cabin's aft flight deck as the Space Shuttle Columbia approached the Hubble Space Telescope. A short time later, the STS-109 crew captured and latched down the giant telescope in the vehicle's cargo bay for several days of work on the Hubble. The image was recorded with a digital still camera.

Determination of armepavine in mouse blood by UPLC-MS/MS and its application to pharmacokinetic study.

PubMed

Geng, Peiwu; Luo, Jun; Weng, Ziwei; Fan, Zhehua; Zhang, Bin; Ma, Jianshe; Wang, Xianqin; Zhang, Meiling

2018-05-03

The purpose of this study was to develop an ultra-performance liquid chromatography with tandem mass spectrometry (UPLC-MS/MS) method to determine armepavine in mouse blood. Nuciferine was used as internal standard. Chromatographic separation was performed on a UPLC BEH (2.1 × 50 mm, 1.7 μm) column with a gradient elution of acetonitrile and 10 mmol/L ammonium acetate solution (containing 0.1% formic acid). The quantitative analysis was conducted in multiple reaction monitoring mode with m/z 314.1 → 106.9 for armepavine and m/z 296.2 → 265.1 for nuciferine. Calibration curves were linear (r > 0.995) over the concentration range 1-1000 ng/mL in mouse blood with a lowest limit of quantitation of 1 ng/mL. The intra- and inter-day precisions of armepavine in mouse were < 13.5 and 10.8%, respectively. The accuracy ranged between 86.8 and 103.3%. Meanwhile, the average recovery was >70.7% and the matrix effect was within the range 109.5-113.7%. All of the obtained data confirmed the satisfactory sensitivity and selectivity of the developed method which was then successfully applied to evaluate the pharmacokinetic behavior of armepavine in mouse for the first time. The bioavailability of armepavine in mouse was calculated to be 11.3%. Copyright © 2018 John Wiley & Sons, Ltd.

Quantitative determination of metformin, glyburide and its metabolites in plasma and urine of pregnant patients by LC-MS/MS

PubMed Central

Zhang, Xing; Wang, Xiaoming; Vernikovskaya, Daria I.; Fokina, Valentina M.; Nanovskaya, Tatiana N.; Hankins, Gary D.V.; Ahmed, Mahmoud S.

2014-01-01

This report describes the development and validation of an LC-MS/MS method for the quantitative determination of glyburide (GLB), its five metabolites (M1, M2a, M2b, M3, and M4) and metformin (MET) in plasma and urine of pregnant patients under treatment with a combination of the two medications. The extraction recovery of the analytes from plasma samples ranged between 87% and 99%, and 85%–95% for urine samples. The differences in retention times among the analytes, and the wide range of the concentrations of the medications and their metabolites in plasma and urine patient samples required the development of three LC methods. The lower limit of quantitation (LLOQ) of the analytes in plasma samples was as follows: GLB, 1.02 ng/mL; its five metabolites, 0.100–0.113 ng/mL and 4.95 ng/mL for MET. LLOQ in urine samples was 0.0594 ng/mL for GLB, 0.984–1.02 ng/mL for its five metabolites and 30.0 μg/mL for MET. The relative deviation of this method was < 14% for intra-day and inter-day assays in plasma and urine samples, and the accuracy ranged between 86% and 114% in plasma, and 94% to 105% in urine. The method described in this report was successfully utilized for determining the concentrations of the two medications in patient plasma and urine. PMID:25164921

Simultaneous determination of polycyclic musks in blood and urine by solid supported liquid-liquid extraction and gas chromatography-tandem mass spectrometry.

PubMed

Liu, Hongtao; Huang, Liping; Chen, Yuxin; Guo, Liman; Li, Limin; Zhou, Haiyun; Luan, Tiangang

2015-06-15

A rapid, precise and accurate method for the simultaneous determination of 5 polycyclic musks (PCMs) in biological fluids was developed by solid supported liquid-liquid extraction (SLE) coupled with gas chromatography-tandem mass spectrometry (GC-MS/MS). All parameters influencing SLE-GC-MS performance, including electron energy of electron-impact ionization source, collision energy for tandem mass spectrometer when operated in selected-reaction monitoring (SRM) mode, type and volume of elution reagent, nitrogen evaporation time, pH and salinity of sample have been carefully optimized. Eight milliliter of n-hexane was finally chosen as elution reagent. Blood and urine sample could be loaded into SLE cartridge without adjusting pH and salinity. Deuterated tonalide (AHTN-d3) was chosen as internal standard. The correlation coefficient (r(2)) of the calibration curves of target compounds ranged from 0.9996 to 0.9998. The dynamic range spanned over two orders of magnitude. The limit of detection (LOD) of target compounds in blood and urine ranged from 0.008 to 0.105μgL(-1) and 0.005 to 0.075μgL(-1), respectively. The developed procedure was successfully applied to the analysis of PCMs in human blood and urine obtaining satisfying recoveries on low, medium and high levels. The method was compared with SLE-GC-MS and shown one to two orders of magnitude improvement in sensitivity. Copyright © 2015 Elsevier B.V. All rights reserved.

Canine left ventricle electromechanical behavior under different pacing modes.

PubMed

Vo Thang, Thanh-Thuy; Thibault, Bernard; Finnerty, Vincent; Pelletier-Galarneau, Matthieu; Khairy, Paul; Grégoire, Jean; Harel, François

2012-10-01

Cardiac resynchronization therapy may improve survival and quality of life in patients suffering from heart failure with left ventricular (LV) contraction dyssynchrony. While several studies have investigated electrical or mechanical determinants of synchronous contraction, few have focused on activation contraction coupling at a macroscopic level. The objective of the study was to characterize LV electromechanical behavior and response to pacing in a heart failure model. We analyzed data from 3D electroanatomic non-contact mapping and blood pool SPECT for 12 dogs with right ventricular (RV) tachycardia pacing-induced dilated cardiomyopathy. Surfaces generated by the two modalities were registered. Electrical signals were analyzed, and endocardial wall displacement curves were portrayed. Rapid pacing decreased the mean LV ejection fraction (LVEF) to 20.9 % and prolonged the QRS duration to 79 ± 10 ms (normal range: 40-50 ms). QRS duration remained unchanged with biventricular pacing (88.5 ms), while single site pacing further prolonged the QRS duration (113.3 ms for RV pacing and 111.6 ms for LV pacing). No trend was observed in LV systolic function. Activation duration time was significantly increased with all pacing modes compared to baseline. Finally, electromechanical delay, as defined by the delay between electrical activation and mechanical response, was increased by single site pacing (172.9 ms for RV pacing and 174.6 ms for LV pacing) but not by biventricular pacing (162.4 ms). Combined temporal and spatial coregistration electroanatomic maps and baseline gated blood pool SPECT imaging allowed us to quantify activation duration time, electromechanical delay, and LVEF for different pacing modes. Even if pacing modes did not significantly modify LVEF or activation duration, they produced alterations in electromechanical delay, with biventricular pacing significantly decreasing the electromechanical delay as measured by surface tracings and endocardial non-contact mapping.

Excess Mortality in Patients with Multiple Sclerosis Starts at 20 Years from Clinical Onset: Data from a Large-Scale French Observational Study

PubMed Central

Leray, Emmanuelle; Vukusic, Sandra; Debouverie, Marc; Clanet, Michel; Brochet, Bruno; de Sèze, Jérôme; Zéphir, Hélène; Defer, Gilles; Lebrun-Frenay, Christine; Moreau, Thibault; Clavelou, Pierre; Pelletier, Jean; Berger, Eric; Cabre, Philippe; Camdessanché, Jean-Philippe; Kalson-Ray, Shoshannah; Confavreux, Christian; Edan, Gilles

2015-01-01

Background Recent studies in multiple sclerosis (MS) showed longer survival times from clinical onset than older hospital-based series. However estimated median time ranges widely, from 24 to 45 years, which makes huge difference for patients as this neurological disease mainly starts around age 20 to 40. Precise and up-to-date reference data about mortality in MS are crucial for patients and neurologists, but unavailable yet in France. Objectives Estimate survival in MS patients and compare mortality with that of the French general population. Methods We conducted a multicenter observational study involving clinical longitudinal data from 30,413 eligible patients, linked to the national deaths register. Inclusion criteria were definite MS diagnosis and clinical onset prior to January, 1st 2009 in order to get a minimum of 1-year disease duration. Results After removing between-center duplicates and applying inclusion criteria, the final population comprised 27,603 MS patients (F/M sex ratio 2.5, mean age at onset 33.0 years, 85.5% relapsing onset). During the follow-up period (mean 15.2 +/- 10.3 years), 1569 deaths (5.7%) were identified; half related to MS. Death rates were significantly higher in men, patients with later clinical onset, and in progressive MS. Overall excess mortality compared with the general population was moderate (Standardized Mortality Ratio 1.48, 95% confidence interval [1.41-1.55]), but increased considerably after 20 years of disease (2.20 [2.10-2.31]). Conclusions This study revealed a moderate decrease in life expectancy in MS patients, and showed that the risk of dying is strongly correlated to disease duration and disability, highlighting the need for early actions that can slow disability progression. PMID:26148099

Rapid and High-Throughput Detection and Quantitation of Radiation Biomarkers in Human and Nonhuman Primates by Differential Mobility Spectrometry-Mass Spectrometry

NASA Astrophysics Data System (ADS)

Chen, Zhidan; Coy, Stephen L.; Pannkuk, Evan L.; Laiakis, Evagelia C.; Hall, Adam B.; Fornace, Albert J.; Vouros, Paul

2016-10-01

Radiation exposure is an important public health issue due to a range of accidental and intentional threats. Prompt and effective large-scale screening and appropriate use of medical countermeasures (MCM) to mitigate radiation injury requires rapid methods for determining the radiation dose. In a number of studies, metabolomics has identified small-molecule biomarkers responding to the radiation dose. Differential mobility spectrometry-mass spectrometry (DMS-MS) has been used for similar compounds for high-throughput small-molecule detection and quantitation. In this study, we show that DMS-MS can detect and quantify two radiation biomarkers, trimethyl-L-lysine (TML) and hypoxanthine. Hypoxanthine is a human and nonhuman primate (NHP) radiation biomarker and metabolic intermediate, whereas TML is a radiation biomarker in humans but not in NHP, which is involved in carnitine synthesis. They have been analyzed by DMS-MS from urine samples after a simple strong cation exchange-solid phase extraction (SCX-SPE). The dramatic suppression of background and chemical noise provided by DMS-MS results in an approximately 10-fold reduction in time, including sample pretreatment time, compared with liquid chromatography-mass spectrometry (LC-MS). DMS-MS quantitation accuracy has been verified by validation testing for each biomarker. Human samples are not yet available, but for hypoxanthine, selected NHP urine samples (pre- and 7-d-post 10 Gy exposure) were analyzed, resulting in a mean change in concentration essentially identical to that obtained by LC-MS (fold-change 2.76 versus 2.59). These results confirm the potential of DMS-MS for field or clinical first-level rapid screening for radiation exposure.

The experience of transitioning from relapsing remitting to secondary progressive multiple sclerosis: views of patients and health professionals.

PubMed

O'Loughlin, Emer; Hourihan, Susan; Chataway, Jeremy; Playford, E Diane; Riazi, Afsane

2017-09-01

The majority of people with multiple sclerosis (pwMS) initially present with discreet periods of relapses followed by partial remission of symptoms (RRMS). Over time, most pwMS transition to secondary progressive MS (SPMS), characterized by a gradual accumulation of disability. This study aimed to explore the experiences, coping and needs associated with transitioning from RRMS to SPMS. Data were collected via semi-structured interviews with nine pwMS and seven specialist MS health professionals (HPs). Thematic analysis was used to analyze the data. Four major themes were identified: "Is this really happening?"; "Becoming a reality"; "A life of struggle"; and "Brushing oneself off and moving on." Findings suggested a process of moving from uncertainty towards confirmation of one's diagnostic label. Being reclassified with SPMS served as a turning point for many, and was accompanied by a range of cognitive, emotional and behavioral responses. The value of adequate information and support surrounding the transition, and the potential benefit of education and support for health professionals in relation to the transition were indicated. Understanding pwMS' experiences of the transition is essential if clinicians are to provide pwMS with appropriate support during the transition. Implications for Rehabilitation The timing and delivery of preparatory education for patients about the transition to SPMS should be carefully considered. Sufficient information and follow-up support following the reclassification of SPMS is crucial but sometimes lacking. The importance of sensitive communication of the reclassification of SPMS was highlighted. MS Specialist health professionals may potentially benefit from training and support around communication of the reclassification of SPMS. Given the potential negative psychological impact of the transition, the psychological wellbeing of the patients during the transition to SPMS should be monitored and responded to appropriately.

Online molecular characterisation of organic aerosols in an atmospheric chamber using extractive electrospray ionisation mass spectrometry

NASA Astrophysics Data System (ADS)

Gallimore, Peter J.; Giorio, Chiara; Mahon, Brendan M.; Kalberer, Markus

2017-12-01

The oxidation of biogenic volatile organic compounds (VOCs) represents a substantial source of secondary organic aerosol (SOA) in the atmosphere. In this study, we present online measurements of the molecular constituents formed in the gas and aerosol phases during α-pinene oxidation in the Cambridge Atmospheric Simulation Chamber (CASC). We focus on characterising the performance of extractive electrospray ionisation (EESI) mass spectrometry (MS) for particle analysis. A number of new aspects of EESI-MS performance are considered here. We show that relative quantification of organic analytes can be achieved in mixed organic-inorganic particles. A comprehensive assignment of mass spectra for α-pinene derived SOA in both positive and negative ion modes is obtained using an ultra-high-resolution mass spectrometer. We compare these online spectra to conventional offline ESI-MS spectra and find good agreement in terms of the compounds identified, without the need for complex sample work-up procedures. Under our experimental conditions, EESI-MS signals arise only from particle-phase analytes. High-time-resolution (7 min) EESI-MS spectra are compared with simulations from the near-explicit Master Chemical Mechanism (MCM) for a range of reaction conditions. We show that MS peak abundances scale with modelled concentrations for condensable products (pinonic acid, pinic acid, OH-pinonic acid). Relative quantification is achieved throughout SOA formation as the composition, size and mass (5-2400 µg m-3) of particles is evolving. This work provides a robust demonstration of the advantages of EESI-MS for chamber studies over offline ESI-MS (time resolution, relative quantification) and over hard online techniques (molecular information).

MS/MS analysis and imaging of lipids across Drosophila brain using secondary ion mass spectrometry.

PubMed

Phan, Nhu T N; Munem, Marwa; Ewing, Andrew G; Fletcher, John S

2017-06-01

Lipids are abundant biomolecules performing central roles to maintain proper functioning of cells and biological bodies. Due to their highly complex composition, it is critical to obtain information of lipid structures in order to identify particular lipids which are relevant for a biological process or metabolic pathway under study. Among currently available molecular identification techniques, MS/MS in secondary ion mass spectrometry (SIMS) imaging has been of high interest in the bioanalytical community as it allows visualization of intact molecules in biological samples as well as elucidation of their chemical structures. However, there have been few applications using SIMS and MS/MS owing to instrumental challenges for this capability. We performed MS and MS/MS imaging to study the lipid structures of Drosophila brain using the J105 and 40-keV Ar 4000 + gas cluster ion source, with the novelty being the use of MS/MS SIMS analysis of intact lipids in the fly brain. Glycerophospholipids were identified by MS/MS profiling. MS/MS was also used to characterize diglyceride fragment ions and to identify them as triacylglyceride fragments. Moreover, MS/MS imaging offers a unique possibility for detailed elucidation of biomolecular distribution with high accuracy based on the ion images of its fragments. This is particularly useful in the presence of interferences which disturb the interpretation of biomolecular localization. Graphical abstract MS/MS was performed during time-of-flight secondary ion mass spectrometry (ToF-SIMS) analysis of Drosophila melongaster (fruit fly) to elucidate the structure and origin of different chemical species in the brain including a range of different phospholipid classes (PC, PI, PE) and di- and triacylglycerides (DAG & TAG) species where reference MS/MS spectra provided a potential means of discriminating between the isobaric [M-OH] + ion of DAGs and the [M-RCO] + ion of TAGs.

Effects of controlled whole-body vibration training in improving fall risk factors among individuals with multiple sclerosis: A pilot study.

PubMed

Yang, Feng; Finlayson, Marcia; Bethoux, Francois; Su, Xiaogang; Dillon, Loretta; Maldonado, Hector M

2018-03-01

The purpose of this study was to systematically examine the effect of an 8-week controlled whole-body vibration training on improving fall risk factors and the bone mineral density among people with multiple sclerosis (PwMS). This study adopted a single group pre-test-post-test design. Twenty-five PwMS (50.3 years SD 14.1) received vibration training on a side-alternating vibration platform. Each training session was repeated three times every week for 8 weeks. Prior to and following the 8-week training course, a battery of fall risk factors were evaluated: the body balance, functional mobility, muscle strength, range of motion, and fear of falling. Bone density at both calcanei was also assessed. Twenty-two participants completed the study. Compared with pre-test, almost all fall risk factors and the bone density measurement were significantly improved at post-test, with moderate to large effect sizes varying between 0.571 and 1.007. The 8-week vibration training was well accepted by PwMS and improved their fall risk factors. The important findings of this study were that vibration training may increase the range of motion of ankle joints on the sagittal plane, lower the fear of falling, and improve bone density. IMPLICATIONS FOR REHABILITATION An 8-week vibration training course could be well-accepted by people with multiple sclerosis (MS). Vibration training improves the risk factors of falls in people living with MS. Vibration training could be a promising rehabilitation intervention in individuals with MS.

Applied Meteorology Unit Quarterly Report. First Quarter FY-13

NASA Technical Reports Server (NTRS)

2013-01-01

The AMU team worked on five tasks for their customers: (1) Ms. Crawford continued work on the objective lightning forecast task for airports in east-central Florida. (2) Ms. Shafer continued work on the task for Vandenberg Air Force Base to create an automated tool that will help forecasters relate pressure gradients to peak wind values. (3) Dr. Huddleston began work to develop a lightning timing forecast tool for the Kennedy Space Center/Cape Canaveral Air Force Station area. (3) Dr. Bauman began work on a severe weather forecast tool focused on east-central Florida. (4) Dr. Watson completed testing high-resolution model configurations for Wallops Flight Facility and the Eastern Range, and wrote the final report containing the AMU's recommendations for model configurations at both ranges.

Chirp-Z analysis for sol-gel transition monitoring.

PubMed

Martinez, Loïc; Caplain, Emmanuel; Serfaty, Stéphane; Griesmar, Pascal; Gouedard, Gérard; Gindre, Marcel

2004-04-01

Gelation is a complex reaction that transforms a liquid medium into a solid one: the gel. In gel state, some gel materials (DMAP) have the singular property to ring in an audible frequency range when a pulse is applied. Before the gelation point, there is no transmission of slow waves observed; after the gelation point, the speed of sound in the gel rapidly increases from 0.1 to 10 m/s. The time evolution of the speed of sound can be measured, in frequency domain, by following the frequency spacing of the resonance peaks from the Synchronous Detection (SD) measurement method. Unfortunately, due to a constant frequency sampling rate, the relative error for low speeds (0.1 m/s) is 100%. In order to maintain a low constant relative error, in the whole speed time evolution range, Chirp-Z Transform (CZT) is used. This operation transforms a time variant signal to a time invariant one using only a time dependant stretching factor (S). In the frequency domain, the CZT enables us to stretch each collected spectrum from time signals. The blind identification of the S factor gives us the complete time evolution law of the speed of sound. Moreover, this method proves that the frequency bandwidth follows the same time law. These results point out that the minimum wavelength stays constant and that it only depends on the gel.

Effect of integrated Yoga and Physical therapy on audiovisual reaction time, anxiety and depression in patients with chronic multiple sclerosis: a pilot study.

PubMed

Chobe, Shivaji; Bhargav, Hemant; Raghuram, Nagarathna; Garner, Christoph

2016-09-01

Multiple sclerosis (MS) is characterized by a significant deterioration in auditory and visual reaction times along with associated depression and anxiety. Yoga and Physical therapy (PT) interventions have been found to enhance recovery from these problems in various neuropsychiatric illnesses, but sufficient evidence is lacking in chronic MS population. The aim of this study was to assess the effect of integrated Yoga and Physical therapy (IYP) on audiovisual reaction times, depression and anxiety in patients suffering from chronic MS. From a neuro-rehabilitation center in Germany, 11 patients (six females) suffering from MS for 19±7.4 years were recruited. Subjects were in the age range of 55.45±10.02 years and had Extended Disability Status Scores (EDSS) below 7. All the subjects received mind-body intervention of integrated Yoga and Physical therapy (IYP) for 3 weeks. The intervention was given in a residential setup. Patients followed a routine involving Yogic physical postures, pranayama, and meditations along with various Physical therapy (PT) techniques for 21 days, 5 days a week, 5 h/day. They were assessed before and after intervention for changes in audiovisual reaction times (using Brain Fit Model No. OT 400), anxiety, and depression [using Hospital Anxiety and Depression Scale (HADS)]. Data was analyzed using paired samples test. There was significant improvement in visual reaction time (p=0.01), depression (p=0.04), and anxiety (p=0.02) scores at the end of 3 weeks as compared to the baseline. Auditory reaction time showed reduction with borderline statistical significance (p=0.058). This pilot project suggests utility of IYP intervention for improving audiovisual reaction times and psychological health in chronic MS patients. In future, randomized controlled trials with larger sample size should be performed to confirm these findings.

Perfluorinated compounds in fish and blood of anglers at Lake Möhne, Sauerland area, Germany.

PubMed

Hölzer, Jürgen; Göen, Thomas; Just, Paul; Reupert, Rolf; Rauchfuss, Knut; Kraft, Martin; Müller, Johannes; Wilhelm, Michael

2011-10-01

Perfluorinated compounds (PFCs) were measured in fish samples and blood plasma of anglers in a cross-sectional study at Lake Möhne, Sauerland area, Germany. Human plasma and drinking water samples were analyzed by solid phase extraction, high-performance liquid chromatography (HPLC), and tandem mass spectrometry (MS/MS). PFCs in fish fillet were measured by ion pair extraction followed by HPLC and MS/MS. PFOS concentrations in 44 fish samples of Lake Möhne ranged between 4.5 and 150 ng/g. The highest median PFOS concentrations have been observed in perches (median: 96 ng/g) and eels (77 ng/g), followed by pikes (37 ng/g), whitefish (34 ng/g), and roaches (6.1 ng/g). In contrast, in a food surveillance program only 11% of fishes at retail sale contained PFOS at detectable concentrations. One hundred five anglers (99 men, 6 women; 14-88 years old; median 50.6 years) participated in the human biomonitoring study. PFOS concentrations in blood plasma ranged from 1.1 to 650 μg/L (PFOA: 2.1-170 μg/L; PFHxS: 0.4-17 μg/L; LOD: 0.1 μg/L). A distinct dose-dependent relationship between fish consumption and internal exposure to PFOS was observed. PFOS concentrations in blood plasma of anglers consuming fish 2-3 times per month were 7 times higher compared to those without any fish consumption from Lake Möhne. The study results strongly suggest that human internal exposure to PFC is distinctly increased by consumption of fish from PFC-contaminated sites.

Rapid wide-scope screening of drugs of abuse, prescription drugs with potential for abuse and their metabolites in influent and effluent urban wastewater by ultrahigh pressure liquid chromatography-quadrupole-time-of-flight-mass spectrometry.

PubMed

Hernández, Félix; Bijlsma, Lubertus; Sancho, Juan V; Díaz, Ramon; Ibáñez, María

2011-01-17

This work illustrates the potential of hybrid quadrupole-time-of-flight mass spectrometry (QTOF MS) coupled to ultrahigh pressure liquid chromatography (UHPLC) to investigate the presence of drugs of abuse in wastewater. After solid-phase extraction with Oasis MCX cartridges, seventy-six illicit drugs, prescription drugs with potential for abuse, and metabolites were investigated in the samples by TOF MS using electrospray interface under positive ionization mode, with MS data acquired over an m/z range of 50-1000Da. For 11 compounds, reference standards were available, and experimental data (e.g., retention time and fragmentation data) could be obtained, facilitating a more confident identification. The use of a QTOF instrument enabled the simultaneous application of two acquisition functions with different collision energies: a low energy (LE) function, where none or poor fragmentation took place, and a high energy (HE) function, where fragmentation in the collision cell was promoted. This approach, known as MS(E), enabled the simultaneous acquisition of full-spectrum accurate mass data of both protonated molecules and fragment ions in a single injection, providing relevant information that facilitates the rapid detection and reliable identification of these emerging contaminants in the sample matrices analyzed. In addition, isomeric compounds, like the opiates, morphine and norcodeine, could be discriminated by their specific fragments observed in HE TOF MS spectra, without the need of reference standards. UHPLC-QTOF MS was proven to be a powerful and efficient technique for rapid wide-scope screening and identification of many relevant drugs in complex matrices, such as influent and effluent urban wastewater. Copyright © 2010 Elsevier B.V. All rights reserved.

Is there a prognostic relevance of electrophysiological studies in bundle branch block patients?

PubMed

Bogossian, Harilaos; Frommeyer, Gerrit; Göbbert, Kornelius; Hasan, Fuad; Nguyen, Quy Suu; Ninios, Ilias; Mijic, Dejan; Bandorski, Dirk; Hoeltgen, Reinhard; Seyfarth, Melchior; Lemke, Bernd; Eckardt, Lars; Zarse, Markus

2017-08-01

The present European guidelines suggest a diagnostic electrophysiological (EP) study to determine indication for cardiac pacing in patients with bundle branch block and unexplained syncope. We evaluated the prognostic relevance of an EP study for mortality and the development of permanent complete atrioventricular (AV) block in patients with symptomatic bifascicular block and first-degree AV block. The HV interval is a poor prognostic marker to predict the development of permanent AV block in patients with symptomatic bifascicular block (BFB) and AV block I°. Thirty consecutive patients (mean age, 74.8 ± 8.6 years; 25 males) with symptomatic BFB and first-degree AV block underwent an EP study before device implantation, according to current guidelines. For 53 ± 31 months, patients underwent yearly follow-up screening for syncope or higher-degree AV block. Thirty patients presented with prolonged HV interval during the EP study (mean, 82.2 ± 20.1 ms; range, 57-142 ms), classified into 3 groups: group 1, <70 ms (mean, 62 ± 4 ms; range, 57-67 ms; n = 7), group 2, >70 to ≤100 ms (mean, 80 ± 8 ms; range, 70-97 ms; n = 18), and group 3, >100 ms (mean, 119 ± 14 ms; range, 107-142 ms; n = 5). According to the guidelines, patients in groups 2 and 3 received a pacemaker. The length of the HV interval was not associated with the later development of third-degree AV block or with increased mortality. Our present study suggests that an indication for pacemaker implantation based solely on a diagnostic EP study with prolongation of the HV interval is not justified. © 2017 Wiley Periodicals, Inc.

Simultaneous UPLC-MS/MS assay for the detection of the traditional antipsychotics haloperidol, fluphenazine, perphenazine, and thiothixene in serum and plasma.

PubMed

Juenke, JoEtta M; Brown, Paul I; Urry, Francis M; Johnson-Davis, Kamisha L; McMillin, Gwendolyn A

2013-08-23

Most antipsychotic drugs that are commonly prescribed in the USA are monitored by liquid and gas chromatographic methods. Method performance has been improved using ultra high pressure liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). A rapid and simple procedure for monitoring haloperidol, thiothixene, fluphenazine, and perphenazine is described here. Antipsychotic drug concentrations in serum and plasma were determined by LCMS/MS (Waters Acquity UPLC TQD). The instrument is operated with an ESI interface, in multiple reaction monitoring (MRM), and positive ion mode. The resolution of both quadrupoles was maintained at unit mass with a peak width at half height of 0.7amu. Data analysis was performed using the Waters Quanlynx software. Serum or plasma samples were thawed at room temperature and a 100μL aliquot was placed in a tube. Then 300μL of precipitating reagent (acetonitrile-methanol [50:50, volume: volume]) containing the internal standard (0.12ng/μL Imipramine-D3) was added to each tube. The samples were vortexed and centrifuged. The supernatant was transferred to an autosampler vial and 8μL was injected into the UPLC-MS/MS. Utilizing a Waters Acquity UPLC HSS T3 1.8μm, 2.1×50mm column at 25ºC, the analytes were separated using a timed, linear gradient of acetonitrile and water, each having 0.1% formic acid added. The column is eluted into the LC-MS/MS to detect imipramine D3 at transition 284.25>89.10, haloperidol at 376.18>165.06, thiothixene at 444.27>139.24, fluphenazine at 438.27>171.11, and perphenazine at 404.19>143.07. Secondary transitions for each analyte are also monitored for imipramine D3 at 284.25>193.10, haloperidol at 376.18>122.97, thiothixene at 444.27>97.93, fluphenazine at 438.27>143.08, and perphenazine at 404.19>171.11. The run-time is 1.8min per injection with baseline resolved chromatographic separation. The analytical measurement range was 0.2 to 12.0ng/mL for fluphenazine and perphenazine, and was 1 to 60.0ng/mL for haloperidol and thiothixene. Intra-assay and inter-assay imprecisions (CV) were less than 15% at two concentrations for each analyte. By utilizing a LC-MS/MS method we combined two previously established analytical assays into one, yielding a 75% time-savings on set-up, and a significantly shortened analytical run-time. These changes reduced the turn-around time for analysis and eliminated interference issues resulting in fewer injections and increased column lifetime. Copyright © 2013 Elsevier B.V. All rights reserved.

A new strategy for faster urinary biomarkers identification by Nano-LC-MALDI-TOF/TOF mass spectrometry

PubMed Central

Benkali, K; Marquet, P; Rérolle, JP; Le Meur, Y; Gastinel, LN

2008-01-01

Background LC-MALDI-TOF/TOF analysis is a potent tool in biomarkers discovery characterized by its high sensitivity and high throughput capacity. However, methods based on MALDI-TOF/TOF for biomarkers discovery still need optimization, in particular to reduce analysis time and to evaluate their reproducibility for peak intensities measurement. The aims of this methodological study were: (i) to optimize and critically evaluate each step of urine biomarker discovery method based on Nano-LC coupled off-line to MALDI-TOF/TOF, taking full advantage of the dual decoupling between Nano-LC, MS and MS/MS to reduce the overall analysis time; (ii) to evaluate the quantitative performance and reproducibility of nano-LC-MALDI analysis in biomarker discovery; and (iii) to evaluate the robustness of biomarkers selection. Results A pool of urine sample spiked at increasing concentrations with a mixture of standard peptides was used as a specimen for biological samples with or without biomarkers. Extraction and nano-LC-MS variabilities were estimated by analyzing in triplicates and hexaplicates, respectively. The stability of chromatographic fractions immobilised with MALDI matrix on MALDI plates was evaluated by successive MS acquisitions after different storage times at different temperatures. Low coefficient of variation (CV%: 10–22%) and high correlation (R2 > 0.96) values were obtained for the quantification of the spiked peptides, allowing quantification of these peptides in the low fentomole range, correct group discrimination and selection of "specific" markers using principal component analysis. Excellent peptide integrity and stable signal intensity were found when MALDI plates were stored for periods of up to 2 months at +4°C. This allowed storage of MALDI plates between LC separation and MS acquisition (first decoupling), and between MS and MSMS acquisitions while the selection of inter-group discriminative ions is done (second decoupling). Finally the recording of MSMS spectra to obtain structural information was focused only on discriminative ions in order to minimize analysis time. Conclusion Contrary to other classical approaches with direct online coupling of chromatographic separation and on the flight MS and/or MSMS data acquisition for all detected analytes, our dual decoupling strategy allowed us to focus on the most discriminative analytes, giving us more time to acquire more replicates of the same urine samples thus increasing detection sensitivity and mass precision. PMID:19014585

Use of Bacteriophage MS2 as an Internal Control in Viral Reverse Transcription-PCR Assays

PubMed Central

Dreier, Jens; Störmer, Melanie; Kleesiek, Knut

2005-01-01

Diagnostic systems based on reverse transcription (RT)-PCR are widely used for the detection of viral genomes in different human specimens. The application of internal controls (IC) to monitor each step of nucleic acid amplification is necessary to prevent false-negative results due to inhibition or human error. In this study, we designed various real-time RT-PCRs utilizing the coliphage MS2 replicase gene, which differ in detection format, amplicon size, and efficiency of amplification. These noncompetitive IC assays, using TaqMan, hybridization probe, or duplex scorpion probe techniques, were tested on the LightCycler and Rotorgene systems. In our approach, clinical specimens were spiked with the control virus to monitor the efficiency of extraction, reverse transcription, and amplification steps. The MS2 RT-PCR assays were applied for internal control when using a second target hepatitis C virus RNA in duplex PCR in blood donor screening. The 95% detection limit was calculated by probit analysis to 44.9 copies per PCR (range, 38.4 to 73.4). As demonstrated routinely, application of MS2 IC assays exhibits low variability and can be applied in various RT-PCR assays. MS2 phage lysates were obtained under standard laboratory conditions. The quantification of phage and template RNA was performed by plating assays to determine PFU or via real-time RT-PCR. High stability of the MS2 phage preparations stored at −20°C, 4°C, and room temperature was demonstrated. PMID:16145106

Characterization of Stevia leaves by LC-QTOF MS/MS analysis of polar and non-polar extracts.

PubMed

Molina-Calle, M; Priego-Capote, F; Luque de Castro, M D

2017-03-15

Stevia is currently a well-known plant thanks to its sweeting power. Numerous studies that elucidate its composition were exclusively focused on determination of steviol and its glycosides. Untargeted analysis was applied to obtain a profile of main compounds present in extracts from Stevia (Stevia rebaudiana Bertoni) leaves using LC-MS in high resolution mode with a quadrupole-time of flight analyzer. Eighty-nine compounds were tentatively identified and classified into different families: flavonoids; quinic and caffeic acids and derivatives; diterpenoids (including steviol and glycosides); sesquiterpenoids; amino acids and derivatives; fatty amides and derivatives; fatty acids and derivatives; oligosaccharides; glycerolipids; purines; and retinoids. New steviol glycosides were tentatively identified and their possible structures proposed. Other compounds were tentatively identified in Stevia for the first time, such as fatty acid amides. These results reveal the wide range of compounds present in Stevia, which could be responsible for the nutraceutical effects ascribed to their leaves. Copyright © 2016 Elsevier Ltd. All rights reserved.

Implementation of Dipolar Resonant Excitation for Collision Induced Dissociation with Ion Mobility/Time-of-Flight MS

PubMed Central

Webb, Ian K.; Chen, Tsung-Chi; Danielson, William F.; Ibrahim, Yehia M.; Tang, Keqi; Anderson, Gordon A.; Smith, Richard D.

2014-01-01

An ion mobility/time-of-flight mass spectrometer (IMS/TOF MS) platform that allows for resonant excitation collision induced dissociation (CID) is presented. Highly efficient, mass-resolved fragmentation without additional excitation of product ions was accomplished and over-fragmentation common in beam-type CID experiments was alleviated. A quadrupole ion guide was modified to apply a dipolar AC signal across a pair of rods for resonant excitation. The method was characterized with singly protonated methionine enkephalin and triply protonated peptide angiotensin I, yielding maximum CID efficiencies of 44% and 84%, respectively. The Mathieu qx,y parameter was set at 0.707 for these experiments to maximize pseudopotential well depths and CID efficiencies. Resonant excitation CID was compared to beam-type CID for the peptide mixture. The ability to apply resonant waveforms in mobility-resolved windows is demonstrated with a peptide mixture yielding fragmentation over a range of mass-to-charge (m/z) ratios within a single IMS-MS analysis. PMID:24470195

Sol-gel titania-coated needles for solid phase dynamic extraction-GC/MS analysis of desomorphine and desocodeine.

PubMed

Su, Chi-Ju; Srimurugan, Sankarewaran; Chen, Chinpiao; Shu, Hun-Chi

2011-01-01

Novel sol-gel titania film coated needles for solid-phase dynamic extraction (SPDE)-GC/MS analysis of desomorphine and desocodeine are described. The high thermal stability of titania film permits efficient extraction and analysis of poorly volatile opiate drugs. The influences of sol-gel reaction time, coating layer, extraction and desorption time and temperature on the SPDE needle performance were investigated. The deuterium labeled internal standard was introduced either during the extraction of analyte or directly injected to GC after the extraction process. The latter method was shown to be more sensitive for the analysis of water and urine samples containing opiate drugs. The proposed conditions provided a wide linear range (from 5-5000 ppb), and satisfactory linearity, with R(2) values from 0.9958 to 0.9999, and prominent sensitivity, LOQs (1.0-5.0 ng/g). The sol-gel titania film coated needle with SPDE-GC/MS will be a promising technique for desomorphine and desocodeine analysis in urine.

Simple and sensitive determination of hydrazine in drinking water by ultra-high-performance liquid chromatography-tandem mass spectrometry after derivatization with naphthalene-2,3-dialdehyde.

PubMed

Oh, Jin-Aa; Shin, Ho-Sang

2015-05-22

An ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed to determine the level of hydrazine in drinking water. The method is based on the derivatization of hydrazine with naphthalene-2,3-dicarboxaldehyde (NDA) in water. The optimum conditions for UPLC-MS/MS detection were determined as follows: derivatization reagent dosage, 50mg/L of NDA; pH 2; and reaction time, 1min; room temperature. The formed derivative was injected into an LC system without extraction or purification procedures. Under the established conditions, the method was used to detect hydrazine in raw drinking water and chlorinated drinking water. The limits of detection and quantification for hydrazine in drinking water were 0.003μg/L and 0.01μg/L, respectively. The accuracy was in the range of 97-104%, and precision, expressed as relative standard deviation, was less than 9% in drinking water. Hydrazine was detected at a concentration of 0.13μg/L in one sample among 24 raw drinking water samples and in a range of 0.04-0.45μg/L in three samples among 24 chlorinated drinking water samples. Copyright © 2015 Elsevier B.V. All rights reserved.

Matrix-Assisted Laser Desorption Ionization–Time of Flight (MALDI-TOF) Mass Spectrometry for Detection of Antibiotic Resistance Mechanisms: from Research to Routine Diagnosis

PubMed Central

Chudáčková, Eva; Walková, Radka

2013-01-01

Matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) has been successfully applied as an identification procedure in clinical microbiology and has been widely used in routine laboratory practice because of its economical and diagnostic benefits. The range of applications of MALDI-TOF MS has been growing constantly, from rapid species identification to labor-intensive proteomic studies of bacterial physiology. The purpose of this review is to summarize the contribution of the studies already performed with MALDI-TOF MS concerning antibiotic resistance and to analyze future perspectives in this field. We believe that current research should continue in four main directions, including the detection of antibiotic modifications by degrading enzymes, the detection of resistance mechanism determinants through proteomic studies of multiresistant bacteria, and the analysis of modifications of target sites, such as ribosomal methylation. The quantification of antibiotics is suggested as a new approach to study influx and efflux in bacterial cells. The results of the presented studies demonstrate that MALDI-TOF MS is a relevant tool for the detection of antibiotic resistance and opens new avenues for both clinical and experimental microbiology. PMID:23297261

PTR-MS in Italy: A Multipurpose Sensor with Applications in Environmental, Agri-Food and Health Science

PubMed Central

Cappellin, Luca; Loreto, Francesco; Aprea, Eugenio; Romano, Andrea; del Pulgar, José Sánchez; Gasperi, Flavia; Biasioli, Franco

2013-01-01

Proton Transfer Reaction Mass Spectrometry (PTR-MS) has evolved in the last decade as a fast and high sensitivity sensor for the real-time monitoring of volatile compounds. Its applications range from environmental sciences to medical sciences, from food technology to bioprocess monitoring. Italian scientists and institutions participated from the very beginning in fundamental and applied research aiming at exploiting the potentialities of this technique and providing relevant methodological advances and new fundamental indications. In this review we describe this activity on the basis of the available literature. The Italian scientific community has been active mostly in food science and technology, plant physiology and environmental studies and also pioneered the applications of the recently released PTR-ToF-MS (Proton Transfer Reaction-Time of Flight-Mass Spectrometry) in food science and in plant physiology. In the very last years new results related to bioprocess monitoring and health science have been published as well. PTR-MS data analysis, particularly in the case of the ToF based version, and the application of advanced chemometrics and data mining are also aspects characterising the activity of the Italian community. PMID:24021966

Application of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) in Alzheimer's disease.

PubMed

Grela, Agatha; Turek, Agata; Piekoszewski, Wojciech

2012-02-11

Alzheimer's disease is becoming an increasing problem in our aging society. According to our knowledge, so far, no effective pharmacotherapy to cure the cause of the disease has been developed. Therefore, early diagnosis is needed, which will result in implementation of a drug therapy aimed at decreasing and/or inhibiting disease development. Mass spectrometry techniques (MS) have a wide range of applications in proteomics and the search for biomarkers of neurodegenerative disorders, opening new possibilities in diagnostics. Identification of proteins in body fluids (like cerebrospinal fluid or blood) is possible due to MS spectra analysis. The detected changes in protein concentrations are connected with pathological states in an organism and, therefore, can be regarded as biomarkers. Developing procedures for proteome analysis might result in fast diagnosis, as well as creating better suited pharmaceuticals. This paper reviews the search of biomarkers in cerebrospinal fluid and blood. Later on, the use of matrix-assisted-laser-desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) in proteomics, focusing on blood-related biomarkers, is discussed. The aim of the work is also to highlight the advantages and disadvantages of MALDI-TOF-based analyses.

Accelerated solvent extraction combined with solid phase extraction for the determination of organophosphate esters from sewage sludge compost by UHPLC-MS/MS.

PubMed

Pang, Long; Yang, Peijie; Ge, Liming; Du, Jingjing; Zhang, Hongzhong

2017-02-01

Organophosphate esters (OPEs), widely used as flame retardants and plasticizers, are regarded as emerging pollutants. OPEs are prone to concentrate into residual activated sludge, which might cause secondary pollution if not suitably treated. Composting is an economical and effective approach to make sewage sludge stable and harmless. Therefore, it is essential to develop a novel method for analyzing OPEs in sewage sludge compost samples. However, in the composting process, large amounts of amendments are doped into the sludge to adjust the carbon-nitrogen ratio. Amendment has a strong capacity for adsorption and thus induces a decrease of extraction efficiency. This study developed a novel procedure for determining OPEs in compost samples. Accelerated solvent extraction (ASE) and solid phase extraction (SPE) were used for extracting and concentrating the OPEs from sewage sludge compost samples, and then analyzed by UHPLC-MS/MS. Some parameters were optimized in this study, mainly including the extraction solvent type, extraction temperature, static extraction time, extraction cycles, and flush volume. Under the optimal conditions, the proposed method showed good linearity between 0.50 and 100 μg kg -1 with regression coefficients in the range of 0.9984-0.9998. Detection limits were in the range of 0.02-3 μg kg -1 with standard deviations ranging from 2 to 6%. Acceptable recoveries between 56 and 119% for samples spiked at different concentration levels were achieved. In contrast, the recoveries merely ranged from 24 to 58% by using ultrasonic-assisted extraction. Graphical abstract A comparison of recoveries between ultrasonic-assisted extraction (UAS) and accelerated solvent extraction (ASE) for organophosphate esters from sewage sludge compost samples.

UPLC-MS/MS assay for the simultaneous determination of ethinyl estradiol, norgestimate and 17-Desacetyl norgestimate at low pg/mL in human plasma.

PubMed

Huang, Mike-Qingtao; Kang, Lijuan; Wang, Weimin; Skee, Donna; Chen, Mu; Lin, Zhongping John; Verhaeghe, Tom; Weng, Naidong

2016-04-01

Previously, because of the difficulty of measuring very low levels (pg/mL) of norgestimate (NGM) due to rapid metabolism to its active and major metabolite, 17-Desacetyl norgestimate (DNGM), only DNGM and the co-administered ethinyl estradiol (EE2) were required to be analyzed in bioequivalence (BE) studies for oral contraceptive NGM/EE2 tablets. Recently, with more sensitive assays available, health authorities have requested that bioequivalence of NGM be also demonstrated in addition to DNGM and EE2. Therefore, it was important to establish a 3-in-1 method for the quantitation of EE2, NGM and DNGM in human plasma. Here a UPLC-MS/MS method for the simultaneous quantitation of EE2, NGM and DNGM in human plasma at low pg/mL range is described. EE2, NGM, DNGM and their isotopic labeled internal standards (IS) EE2-d4, NGM-d6 and DNGM-d6 in 0.4mL of human plasma were extracted with hexane/ethyl acetate. The extracts were evaporated to dryness and derivatized with dansyl chloride, to enhance the mass spec response. The derivatives were reconstituted with methanol and analyzed by UPLC-MS/MS. In order to minimize the ex-vivo conversion of NGM to DNGM, sodium fluoride/potassium oxalate was used as anti-coagulant. To achieve desirable throughput for sample analysis, UPLC-MS/MS with a run time of 4.4min was utilized. The calibration curve ranges were 5-500pg/mL for EE2 and NGM, and 25-2500pg/mL for DNGM, respectively. The chromatographic separation was achieved on a Waters Acquity UPLC HSS T3 (100×2.1mm, 1.8μm) column with a gradient elution. Assay accuracy, precision, linearity, selectivity, sensitivity and analyte stability covering sample storage and analysis were established. This validated UPLC-MS/MS method has been applied to a BE study for the determination of EE2, NGM and DNGM concentrations in human plasma. Copyright © 2016 Elsevier B.V. All rights reserved.

Harmonized Collaborative Validation of Aflatoxins and Sterigmatocystin in White Rice and Sorghum by Liquid Chromatography Coupled to Tandem Mass Spectrometry

PubMed Central

Ok, Hyun Ee; Tian, Fei; Hong, Eun Young; Paek, Ockjin; Kim, Sheen-Hee; Kim, Dongsul; Chun, Hyang Sook

2016-01-01

An interlaboratory study was performed in eight laboratories to validate a liquid chromatography–tandem mass spectrometry (LC/MS/MS) method for the simultaneous determination of aflatoxins and sterigmatocystin (STC) in white rice and sorghum (Sorghum bicolor). Fortified samples (at three different levels) of white rice and sorghum were extracted, purified through a solid-phase extraction (SPE) column, and then analyzed by LC/MS/MS. The apparent recoveries (ARs) ranged from 78.8% to 95.0% for aflatoxins and from 85.3% to 96.7% for STC. The relative standard deviations for repeatability (RSDr) and reproducibility (RSDR) of aflatoxins were in the ranges 7.9%–33.8% and 24.4%–81.0%, respectively. For STC, the RSDr ranged from 7.1% to 40.2% and the RSDR ranged from 28.1% to 99.2%. The Horwitz ratio values for the aflatoxins and STC ranged from 0.4 to 1.2 in white rice and from 0.3 to 1.0 in sorghum, respectively. These results validated this method for the simultaneous determination of aflatoxins and STC by LC/MS/MS after SPE column cleanup. The percentages of satisfactory Z-score values (|Z| ≤ 2) were the following: for white rice, 100% for aflatoxins and STC; for sorghum, 100%, except in data from two laboratories for STC (0.3 μg/kg). This validated that the LC/MS/MS method was successfully applied for the determination of aflatoxins and STC in 20 white rice and 20 sorghum samples sourced from Korean markets. PMID:27983588

Development of a chiral micellar electrokinetic chromatography-tandem mass spectrometry assay for simultaneous analysis of warfarin and hydroxywarfarin metabolites: application to the analysis of patients serum samples.

PubMed

Wang, Xiaochun; Hou, Jingguo; Jann, Michael; Hon, Yuen Yi; Shamsi, Shahab A

2013-01-04

The enantioseparation of warfarin (WAR) along with the five positional and optical isomers is challenging because of the difficulty to simultaneously separate and quantitate these chiral compounds. Currently, no effective chiral CE-MS methods exist for the simultaneous enantioseparation of WAR and all its hydroxylated metabolites in a single run. Polymeric surfactants (aka. molecular micelles) are particularly compatible with micellar electrokinetic chromatography-mass spectrometry (MEKC-MS) because they have a wider elution window for enantioseparation and do not interfere with the MS detection of chiral drugs. Using polysodium N-undecenoyl-L,L-leucylvalinate (poly-L,L-SULV) as a chiral pseudophase in MEKC-MS baseline separation of WAR, its five metabolites along with the internal standard was obtained in 45 min. This is in comparison to 100 min required for separation of the same mixture with packed column CEC-MS using a vancomycin chiral stationary phase. Serum samples were extracted with mixed-mode anion-exchange (MAX) cartridge with recoveries of greater than 85.2% for all WAR and hydroxywarfarin (OH-WAR) metabolites. Utilizing the tandem MS and multiple reaction monitoring mode, the MEKC-MS/MS method was used to simultaneously generate calibration curves over a concentration range from 2 to 5000 ng/mL for R- and S-warfarin, 5 to 1000 ng/mL for R- and S-6-, 7-, 8- and 10-OH-WAR and 10 to 1000 ng/mL for R and S-4'-OH-WAR. For the first time, the limits of detection and quantitation for most WAR metabolites by MEKC-MS/MS were found to be at levels of 2 and 5 ng/mL, respectively. The method was successfully applied for the first time to analyze WAR and its metabolites in plasma samples of 55 patients undergoing WAR therapy, demonstrating the potential of chiral MEKC-MS/MS method to accurately quantitate with high sensitivity. Copyright © 2012 Elsevier B.V. All rights reserved.

Simultaneous determination of 12 pharmaceuticals in water samples by ultrasound-assisted dispersive liquid-liquid microextraction coupled with ultra-high performance liquid chromatography with tandem mass spectrometry.

PubMed

Guan, Jin; Zhang, Chi; Wang, Yang; Guo, Yiguang; Huang, Peiting; Zhao, Longshan

2016-11-01

A new analytical method was developed for simultaneous determination of 12 pharmaceuticals using ultrasound-assisted dispersive liquid-liquid microextraction (DLLME) followed by ultra-high performance liquid chromatography with tandem mass spectrometry (UHPLC-MS/MS). Six nonsteroidal anti-inflammatory drugs (NSAIDs, ketoprofen, mefenamic acid, tolfenamic acid, naproxen, sulindac, and piroxicam) and six antibiotics (tinidazole, cefuroxime axetil, ciprofloxacin, sulfamethoxazole, sulfadiazine, and chloramphenicol) were extracted by ultrasound-assisted DLLME using dichloromethane (800 μL) and methanol/acetonitrile (1:1, v/v, 1200 μL) as the extraction and dispersive solvents, respectively. The factors affecting the extraction efficiency, such as the type and volume of extraction and dispersive solvent, vortex and ultrasonic time, sample pH, and ionic strength, were optimized. The ultrasound-assisted process was applied to accelerate the formation of the fine cloudy solution by using a small volume of dispersive solvent, which increased the extraction efficiency and reduced the equilibrium time. Under the optimal conditions, the calibration curves showed good linearity in the range of 0.04-20 ng mL -1 (ciprofloxacin and sulfadiazine), 0.2-100 ng mL -1 (ketoprofen, tinidazole, cefuroxime axetil, naproxen, sulfamethoxazole, and sulindac), and 1-200 ng mL -1 (mefenamic acid, tolfenamic acid, piroxicam, and chloramphenicol). The LODs and LOQs of the method were in the range of 0.006-0.091 and 0.018-0.281 ng mL -1 , respectively. The relative recoveries of the target analytes were in the range from 76.77 to 99.97 % with RSDs between 1.6 and 8.8 %. The developed method was successfully applied to the extraction and analysis of 12 pharmaceuticals in five kinds of water samples (drinking water, running water, river water, influent and effluent wastewater) with satisfactory results. Graphical Abstract Twelve pharmaceuticals in water samples analyted by UHPLC-MS/MS using ultrasound-assisted DLLME.

Toxicity of Gamma Knife Radiosurgery in the Treatment of Intracranial Tumors in Patients With Collagen Vascular Diseases or Multiple Sclerosis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lowell, Dot; Tatter, Stephen B.; Bourland, J. Daniel

Purpose: To assess toxicity in patients with either a collagen vascular disease (CVD) or multiple sclerosis (MS) treated with intracranial radiosurgery. Methods and Materials: Between January 2004 and April 2009, 6 patients with MS and 14 patients with a CVD were treated with Gamma Knife radiosurgery (GKRS) for intracranial tumors. Treated lesions included 15 total brain metastases in 7 patients, 11 benign brain tumors, 1 low grade glioma, and 1 cavernous malformation. Toxicities were graded by the Radiation Therapy Oncology Group Acute/Late Radiation Morbidity Scoring Criteria. 'Rare toxicities' were characterized as those reported in the scientific literature at an incidencemore » of <5%. Results: Median follow-up time was 16 months. Median dose to the tumor margin was 13.0 Gy (range, 12-21 Gy). Median size of tumor was 5.0 cm{sup 3} (range, 0.14-7.8 cm{sup 3}). Of the 14 patients with CVD, none experienced a Grade 3 or 4 toxicity or a toxicity characterized as rare. Of the 6 patients with MS, 3 experienced rare toxicities, and two of these were Grade 3 toxicities. Rare complications included a patient experiencing both communicating hydrocephalus and facial nerve palsy, as well as 2 additional patients with motor cranial nerve palsy. High-grade toxicities included the patient with an acoustic neuroma requiring ventriculoperitoneal shunt placement for obstructive hydrocephalus, and 1 patient with a facial nerve schwannoma who experienced permanent facial nerve palsy. Interval between radiosurgery and high-grade toxicities ranged from 1 week to 4 months. Conclusions: Our series suggests that patients with MS who receive GKRS may be at increased risk of rare and high-grade treatment-related toxicity. Given the time course of toxicity, treatment-related edema or demyelination represent potential mechanisms.« less

Performance of coagulation tests in patients on therapeutic doses of rivaroxaban. A cross-sectional pharmacodynamic study based on peak and trough plasma levels.

PubMed

Francart, Suzanne J; Hawes, Emily M; Deal, Allison M; Adcock, Dorothy M; Gosselin, Robert; Jeanneret, Cheryl; Friedman, Kenneth D; Moll, Stephan

2014-06-01

Knowledge of anticoagulation status during rivaroxaban therapy is desirable in certain clinical situations. It was the study objective to determine coagulation tests most useful for assessing rivaroxaban's anticoagulant effect. Peak and trough blood samples from 29 patients taking rivaroxaban 20 mg daily were collected. Mass spectrometry and various coagulation assays were performed. "On-therapy range" was defined as the rivaroxaban concentrations determined by LC-MS/MS. A "misprediction percentage" was calculated based on how often results of each coagulation assay were in the normal reference range, while the rivaroxaban concentration was in the "on-therapy" range. The on-therapy range was 8.9-660 ng/ml. The misprediction percentages for prothrombin time (PT) and activated partial thromboplastin time (aPTT), using multiple reagents and coagulometers, ranged from 10%-52% and 31%-59%, respectively. PT, aPTT and activated clotting time (ACT) were insensitive to trough rivaroxaban: 59%, 62%, and 80% of samples had a normal result, respectively. Over 95% of PT and ACT values were elevated at peak. Four different rivaroxaban calibrated anti-Xa assays had R² values >0.98, demonstrating strong correlations with rivaroxaban drug levels. In conclusion, PT, aPTT and ACT are often normal in patients on therapeutic doses of rivaroxaban. However, PT and ACT may have clinical utility at higher drug plasma levels. Rivaroxaban calibrated anti-factor Xa assays can accurately identify low and high on-therapy rivaroxaban drug levels and, therefore, have superior utility in all clinical situations where assessment of anticoagulation status may be beneficial.

The timing and extent of Quaternary glaciation of Stok, northern Zanskar Range, Transhimalaya, of northern India

NASA Astrophysics Data System (ADS)

Orr, Elizabeth N.; Owen, Lewis A.; Murari, Madhav K.; Saha, Sourav; Caffee, Marc W.

2017-05-01

The glacial history of three tributary valleys (Namlung, Gopal Kangri and Stok Kangri) of the Stok valley, south of the Indus valley in the northern sector of the Zanskar Range, northern India is characterized using geomorphic mapping and cosmogenic 10Be surface exposure dating. The new glacial chronostratigraphy for the Stok valley is the first for the northern Zanskar Range and provides insights into the spatial variability of glaciation in the Himalayan-Tibetan orogen. This framework facilitates the understanding of the nature and the timing of landscape evolution and paleoenvironmental change in the Himalayan-Tibetan orogen. At least four glacial stages are evident within each of the tributary valleys of Gopal Kangri (MG1-MG4, youngest to oldest) and Stok Kangri (MS1-MS4) that feed into the Stok valley. With the exception of the MG4 glacial advance ( 124 ka) in Gopal Kangri, the Stok valley has preserved evidence of glaciations from 50 ka to the present. Equilibrium-line altitudes and glacier reconstructions for the Stok valley and its tributaries demonstrate that glaciations have become progressively less extensive through time. Former glacier extents of the Stok region are comparable in length with glacial advances during the last glacial cycle in eastern Zanskar and in the southern Ladakh Range to the south and north of the Indus valley, respectively. Landscape evolution in the study area has occurred across numerous glacial-interglacial cycles by a combination of glacial and fluvial processes and is similar to that of the Ladakh Range.

Monitoring of protease catalyzed reactions by quantitative MALDI MS using metal labeling.

PubMed

Gregorius, Barbara; Jakoby, Thomas; Schaumlöffel, Dirk; Tholey, Andreas

2013-05-21

Quantitative mass spectrometry is a powerful tool for the determination of enzyme activities as it does not require labeled substrates and simultaneously allows for the identification of reaction products. However, major restrictions are the limited number of samples which can be measured in parallel due to the need for isotope labeled internal standards. Here we describe the use of metal labeling of peptides for the setup of multiplexed enzyme activity assays. After proteolytic reaction, using the protease trypsin, remaining substrates and peptide products formed in the reaction were labeled with metal chelators complexing rare earth metal ions. Labeled peptides were quantified with high accuracy and over a wide dynamic range (at least 2 orders of magnitude) using MALDI MS in case of simple peptide mixtures or by LC-MALDI MS for complex substrate mixtures and used for the monitoring of time-dependent product formation and substrate consumption. Due to multiplexing capabilities and accuracy, the presented approach will be useful for the determination of enzyme activities with a wide range of biochemical and biotechnological applications.

Microsomal metabolism of calycosin, formononetin and drug-drug interactions by dynamic microdialysis sampling and HPLC-DAD-MS analysis.

PubMed

Wen, Xiao-Dong; Qi, Lian-Wen; Li, Bin; Li, Ping; Yi, Ling; Wang, Ya-Qiong; Liu, E-Hu; Yang, Xiao-Lin

2009-08-15

A dynamic microdialysis sampling method with liquid chromatography-diode array detection and time-of-flight mass spectrometry (LC-DAD-TOF/MS) analysis was developed to investigate rat microsomal metabolisms of calycosin and formononetin, and their drug-drug interactions. Two hydroxylated metabolites from calycosin, and three hydroxylated or 4'-O-demethylated derivatives from formononetin were detected and identified after co-incubation with microsomes. Calibration curves offered linear ranges of two orders of magnitude with r(2)>0.999 for calycosin, formononetin and daidzein. The quantitative LC method provides a range of 0.028-0.034microg/mL for limits of detection, overall precision less than 5% and accuracy less than 3% by RSD. Besides, calycosin and formononetin were found to produce the depressive effect on the CYP450 enzyme reaction, and inhibit phase I enzyme reaction of each other when they are concurrent. Dynamic microdialysis sampling with LC-DAD-TOF/MS analysis developed in this work is a powerful tool for in vitro metabolism studies of drugs and metabolic interactions.

Identification and quantification of synthetic cannabinoids in "spice-like" herbal mixtures: Update of the German situation for the spring of 2016.

PubMed

Langer, Nico; Lindigkeit, Rainer; Schiebel, Hans-Martin; Papke, Uli; Ernst, Ludger; Beuerle, Till

2016-12-01

In February 2016, nine "spice-like" products from German language internet shops were analyzed. In total, eight different synthetic cannabinoids were identified by gas chromatography-mass spectrometry (GC-MS), namely THJ-018, THJ-2201, MAB-CHMINACA, 5F-ADB, 5Cl-AKB48 (syn.: 5C-AKB48), 4-pentenyl-AKB48, MDMB-CHMICA and 5F-AB-PINACA. For the majority of products only one synthetic cannabinoid was identified as the active ingredient, while two products contained 2 and 5 compounds, respectively. For some of the identified cannabinoids (MAB-CHMINACA, 5Cl-AKB48 and 4-pentenyl-AKB48) no or only insufficient physico-chemical data were available in literature. To our knowledge 5Cl-AKB48 and 4-pentenyl-AKB48 were found for the first time in commercially available products, hence an in-depth characterization of these compounds by NMR, EI-MS, ESI-MS/MS, IR- and UV spectroscopy was conducted. In addition, all synthetic cannabinoids were quantified by a GC-MS method using JWH-018 as internal standard and the corresponding response factors to calculate the total amount of all synthetic cannabinoids in the commercial smoking mixtures. The content of synthetic cannabinoids in the investigated products ranged from 23 to 120mg/g (average: 57mg/g), while individual compounds ranged from 1 to 120mg/g. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Single Doses up to 800 mg of E-52862 Do Not Prolong the QTc Interval – A Retrospective Validation by Pharmacokinetic-Pharmacodynamic Modelling of Electrocardiography Data Utilising the Effects of a Meal on QTc to Demonstrate ECG Assay Sensitivity

PubMed Central

Täubel, Jörg; Ferber, Georg; Lorch, Ulrike; Wang, Duolao; Sust, Mariano; Camm, A. John

2015-01-01

Background E-52862 is a Sigma-1 receptor antagonist (S1RA) currently under investigation as a potential analgesic medicine. We successfully applied a concentration-effect model retrospectively to a four-way crossover Phase I single ascending dose study and utilized the QTc shortening effects of a meal to demonstrate assay sensitivity by establishing the time course effects from baseline in all four periods, independently from any potential drug effects. Methods Thirty two healthy male and female subjects were included in four treatment periods to receive single ascending doses of 500 mg, 600 mg or 800 mg of E-52862 or placebo. PK was linear over the dose range investigated and doses up to 600 mg were well tolerated. The baseline electrocardiography (ECG) measurements on Day-1 were time-matched with ECG and pharmacokinetic (PK) samples on Day 1 (dosing day). Results In this conventional mean change to time-matched placebo analysis, the largest time-matched difference to placebo QTcI was 1.44 ms (90% CI: -4.04, 6.93 ms) for 500 mg; -0.39 ms (90% CI: -3.91, 3.13 ms) for 600 mg and 1.32 ms (90% CI: -1.89, 4.53 ms) for 800 mg of E-52862, thereby showing the absence of any QTc prolonging effect at the doses tested. In addition concentration-effect models, one based on the placebo corrected change from baseline and one for the change of QTcI from average baseline with time as fixed effect were fitted to the data confirming the results of the time course analysis. Conclusion The sensitivity of this study to detect small changes in the QTc interval was confirmed by demonstrating a shortening of QTcF of -8.1 (90% CI: -10.4, -5.9) one hour and -7.2 (90% CI: -9.4, -5.0) three hours after a standardised meal. Trial Registration EU Clinical Trials Register EudraCT 2010 020343 13 PMID:26291080

Single Doses up to 800 mg of E-52862 Do Not Prolong the QTc Interval--A Retrospective Validation by Pharmacokinetic-Pharmacodynamic Modelling of Electrocardiography Data Utilising the Effects of a Meal on QTc to Demonstrate ECG Assay Sensitivity.

PubMed

Täubel, Jörg; Ferber, Georg; Lorch, Ulrike; Wang, Duolao; Sust, Mariano; Camm, A John

2015-01-01

E-52862 is a Sigma-1 receptor antagonist (S1RA) currently under investigation as a potential analgesic medicine. We successfully applied a concentration-effect model retrospectively to a four-way crossover Phase I single ascending dose study and utilized the QTc shortening effects of a meal to demonstrate assay sensitivity by establishing the time course effects from baseline in all four periods, independently from any potential drug effects. Thirty two healthy male and female subjects were included in four treatment periods to receive single ascending doses of 500 mg, 600 mg or 800 mg of E-52862 or placebo. PK was linear over the dose range investigated and doses up to 600 mg were well tolerated. The baseline electrocardiography (ECG) measurements on Day-1 were time-matched with ECG and pharmacokinetic (PK) samples on Day 1 (dosing day). In this conventional mean change to time-matched placebo analysis, the largest time-matched difference to placebo QTcI was 1.44 ms (90% CI: -4.04, 6.93 ms) for 500 mg; -0.39 ms (90% CI: -3.91, 3.13 ms) for 600 mg and 1.32 ms (90% CI: -1.89, 4.53 ms) for 800 mg of E-52862, thereby showing the absence of any QTc prolonging effect at the doses tested. In addition concentration-effect models, one based on the placebo corrected change from baseline and one for the change of QTcI from average baseline with time as fixed effect were fitted to the data confirming the results of the time course analysis. The sensitivity of this study to detect small changes in the QTc interval was confirmed by demonstrating a shortening of QTcF of -8.1 (90% CI: -10.4, -5.9) one hour and -7.2 (90% CI: -9.4, -5.0) three hours after a standardised meal. EU Clinical Trials Register EudraCT 2010 020343 13.

Study of sample preparation for determination of endocannabinoids and analogous compounds in human serum by LC-MS/MS in MRM mode.

PubMed

Luque-Córdoba, D; Calderón-Santiago, M; Luque de Castro, M D; Priego-Capote, F

2018-08-01

Endocannabinoids are lipids with a key role in physiological processes such as the immune response or the metabolism. This involvement explains their association to pathologies such as cancer, obesity or multiple sclerosis. The determination of endocannabinoids constitutes a challenge for clinical laboratories due to the variety of biological matrices and the wide range of concentrations at which they can be found. This research deals with the comparison of three sample preparation strategies (viz., on-line SPE, off-line SPE for interferents removal, and protein precipitation) for subsequent LC-MS/MS analysis of 14 endocannabinoids and analogous compounds in serum. As a result, the on-line coupling between SPE and LC-MS/MS is proposed as the best approach for this determination. The proposed method allows full automation of the overall process, shortening of the analysis time, and avoidance of errors associated with sample preparation steps. The improvement in sensitivity and selectivity thus achieved allows obtaining quantification limits at the pg mL -1 level, which makes possible the application of the method for clinical studies. Copyright © 2018 Elsevier B.V. All rights reserved.

Comparison of different amino acid derivatives and analysis of rat brain microdialysates by liquid chromatography tandem mass spectrometry.

PubMed

Uutela, Päivi; Ketola, Raimo A; Piepponen, Petteri; Kostiainen, Risto

2009-02-09

The efficiencies of three derivatisation reagents that react with either the amine (9-fluorenylmethyl chloroformate (FMOC)) or the carboxylic acid group (butanol) of amino acid or with both types of functional groups (propyl chloroformate) were compared in the analysis of amino acids by liquid chromatography-electrospray-tandem mass spectrometry (LC-ESI-MS/MS). Separation of 20 amino acids derivatised with these three reagents was studied on reversed-phase chromatography. Linearity, repeatability and limits of detection of the LC-ESI-MS/MS method were determined by analysing FMOC-, butanol- and propyl chloroformate-derivatised lysine, beta-aminobutyric acid, threonine and glutamic acid. The limits of detection for the derivatised amino acids (7.5-75fmol) were as much as 2-60 times lower than those of the corresponding underivatised molecules. The best linearity was observed for amino acids derivatised with propyl chloroformate or butanol (r(2)=0.996-0.999, range=100-8500nmolL(-1)). Propyl chloroformate was the best suited of the reagents tested for the analysis of amino acids with LC-MS/MS and was used for the analysis of amino acids in rat brain microdialysis samples.

Rapid and precise measurement of serum branched-chain and aromatic amino acids by isotope dilution liquid chromatography tandem mass spectrometry.

PubMed

Yang, Ruiyue; Dong, Jun; Guo, Hanbang; Li, Hongxia; Wang, Shu; Zhao, Haijian; Zhou, Weiyan; Yu, Songlin; Wang, Mo; Chen, Wenxiang

2013-01-01

Serum branched-chain and aromatic amino acids (BCAAs and AAAs) have emerged as predictors for the future development of diabetes and may aid in diabetes risk assessment. However, the current methods for the analysis of such amino acids in biological samples are time consuming. An isotope dilution liquid chromatography tandem mass spectrometry (ID-LC/MS/MS) method for serum BCAAs and AAAs was developed. The serum was mixed with isotope-labeled BCAA and AAA internal standards and the amino acids were extracted with acetonitrile, followed by analysis using LC/MS/MS. The LC separation was performed on a reversed-phase C18 column, and the MS/MS detection was performed via the positive electronic spray ionization in multiple reaction monitoring mode. Specific analysis of the amino acids was achieved within 2 min. Intra-run and total CVs for the amino acids were less than 2% and 4%, respectively, and the analytical recoveries ranged from 99.6 to 103.6%. A rapid and precise method for the measurement of serum BCAAs and AAAs was developed and may serve as a quick tool for screening serum BCAAs and AAAs in studies assessing diabetes risk.

Optimization of Sample Preparation and Instrumental Parameters for the Rapid Analysis of Drugs of Abuse in Hair samples by MALDI-MS/MS Imaging

NASA Astrophysics Data System (ADS)

Flinders, Bryn; Beasley, Emma; Verlaan, Ricky M.; Cuypers, Eva; Francese, Simona; Bassindale, Tom; Clench, Malcolm R.; Heeren, Ron M. A.

2017-08-01

Matrix-assisted laser desorption/ionization-mass spectrometry imaging (MALDI-MSI) has been employed to rapidly screen longitudinally sectioned drug user hair samples for cocaine and its metabolites using continuous raster imaging. Optimization of the spatial resolution and raster speed were performed on intact cocaine contaminated hair samples. The optimized settings (100 × 150 μm at 0.24 mm/s) were subsequently used to examine longitudinally sectioned drug user hair samples. The MALDI-MS/MS images showed the distribution of the most abundant cocaine product ion at m/z 182. Using the optimized settings, multiple hair samples obtained from two users were analyzed in approximately 3 h: six times faster than the standard spot-to-spot acquisition method. Quantitation was achieved using longitudinally sectioned control hair samples sprayed with a cocaine dilution series. A multiple reaction monitoring (MRM) experiment was also performed using the `dynamic pixel' imaging method to screen for cocaine and a range of its metabolites, in order to differentiate between contaminated hairs and drug users. Cocaine, benzoylecgonine, and cocaethylene were detectable, in agreement with analyses carried out using the standard LC-MS/MS method. [Figure not available: see fulltext.

Advantages of automation in plasma sample preparation prior to HPLC/MS/MS quantification: application to the determination of cilazapril and cilazaprilat in a bioequivalence study.

PubMed

Kolocouri, Filomila; Dotsikas, Yannis; Apostolou, Constantinos; Kousoulos, Constantinos; Soumelas, Georgios-Stefanos; Loukas, Yannis L

2011-01-01

An HPLC/MS/MS method characterized by complete automation and high throughput was developed for the determination of cilazapril and its active metabolite cilazaprilat in human plasma. All sample preparation and analysis steps were performed by using 2.2 mL 96 deep-well plates, while robotic liquid handling workstations were utilized for all liquid transfer steps, including liquid-liquid extraction. The whole procedure was very fast compared to a manual procedure with vials and no automation. The method also had a very short chromatographic run time of 1.5 min. Sample analysis was performed by RP-HPLC/MS/MS with positive electrospray ionization using multiple reaction monitoring. The calibration curve was linear in the range of 0.500-300 and 0.250-150 ng/mL for cilazapril and cilazaprilat, respectively. The proposed method was fully validated and proved to be selective, accurate, precise, reproducible, and suitable for the determination of cilazapril and cilazaprilat in human plasma. Therefore, it was applied to a bioequivalence study after per os administration of 2.5 mg tablet formulations of cilazapril.

Micro-pulverized extraction pretreatment for highly sensitive analysis of 11-nor-9-carboxy-Δ(9)-tetrahydrocannabinol in hair by liquid chromatography/tandem mass spectrometry.

PubMed

Kuwayama, Kenji; Miyaguchi, Hajime; Yamamuro, Tadashi; Tsujikawa, Kenji; Kanamori, Tatsuyuki; Iwata, Yuko T; Inoue, Hiroyuki

2015-11-30

A primary metabolite of Δ(9) -tetrahydrocannabinol, 11-nor-9-carboxytetrahydrocannabinol (THC-COOH), serves as an effective indicator for cannabis intake. According to the recommendations of the Society of Hair Testing, at least 0.2 pg/mg of THC-COOH (cut-off level) must be present in a hair sample to constitute a positive result in a drug test. Typically, hair is digested with an alkaline solution and is subjected to gas chromatography/tandem mass spectrometry (GC/MS/MS) with negative ion chemical ionization (NICI). It is difficult to quantify THC-COOH at the cut-off level using liquid chromatography/tandem mass spectrometry (LC/MS/MS) without acquisition of second-generation product ions in triple quadrupole-ion trap mass spectrometers, because large amounts of matrix components in the low-mass range produced by digestion interfere with the THC-COOH peak. Using the typical pretreatment method (alkaline dissolution) and micro-pulverized extraction (MPE) with a stainless bullet, we compared the quantification of THC-COOH using GC/MS/MS and LC/MS/MS. MPE reduced the amount of matrix components in the low-mass range and enabled the quantification of THC-COOH at 0.2 pg/mg using a conventional triple quadrupole liquid chromatograph coupled to a mass spectrometer. On the other hand, the MPE pretreatment was unsuitable for GC/MS/MS, probably due to matrix components in the high-mass range. The proper combination of pretreatments and instrumental analyses was shown to be important for detecting trace amounts of THC-COOH in hair. In MPE, samples can be prepared rapidly, and LC/MS/MS is readily available, unlike GC/MS/MS with NICI. The combination of MPE and LC/MS/MS might therefore be used in the initial screening for THC-COOH in hair prior to confirmatory analysis using GC/MS/MS with NICI. Copyright © 2015 John Wiley & Sons, Ltd.

LC-MS metabolic profiling of Arabidopsis thaliana plant leaves and cell cultures: optimization of pre-LC-MS procedure parameters.

PubMed

t'Kindt, Ruben; De Veylder, Lieven; Storme, Michael; Deforce, Dieter; Van Bocxlaer, Jan

2008-08-01

This study treats the optimization of methods for homogenizing Arabidopsis thaliana plant leaves as well as cell cultures, and extracting their metabolites for metabolomics analysis by conventional liquid chromatography electrospray ionization mass spectrometry (LC-ESI/MS). Absolute recovery, process efficiency and procedure repeatability have been compared between different pre-LC-MS homogenization/extraction procedures through the use of samples fortified before extraction with a range of representative metabolites. Hereby, the magnitude of the matrix effect observed in the ensuing LC-MS based metabolomics analysis was evaluated. Based on relative recovery and repeatability of key metabolites, comprehensiveness of extraction (number of m/z-retention time pairs) and clean-up potential of the approach (minimum matrix effects), the most appropriate sample pre-treatment was adopted. It combines liquid nitrogen homogenization for plant leaves with thermomixer based extraction using MeOH/H(2)O 80/20. As such, an efficient and highly reproducible LC-MS plant metabolomics set-up is achieved, as illustrated by the obtained results for both LC-MS (8.88%+/-5.16 versus 7.05%+/-4.45) and technical variability (12.53%+/-11.21 versus 9.31%+/-6.65) data in a comparative investigation of A. thaliana plant leaves and cell cultures, respectively.

A quantitative determination of fluorochloridone in rat plasma by UPLC-MS/MS method: application to a pharmacokinetic study.

PubMed

Liu, Shihong; Shi, Jingmin; Fan, Junpei; Sun, Jie; Zhang, Suhui; Hu, Yue; Wei, Li; Wu, Chunhua; Chang, Xiuli; Tang, Liming; Zhou, Zhijun

2016-08-01

A precise, high-throughput and sensitive ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method has been developed for the determination of fluorochloridone (FLC) in rat plasma. The extraction of analytes from plasma samples was carried out by protein precipitation procedure using acetonitrile prior to UPLC-MS/MS analysis. Verapamil was proved as a proper internal standard (IS) among many candidates. The chromatographic separation based on UPLC was well optimized. Multiple reaction monitoring in positive electrospray ionization was used with the optimized MS transitions at: m/z 312.0 → 292.0 for FLC and m/z 456.4 → 165.2 for IS. This method was well validated with good linear response (r(2)  > 0.998) observed over the investigated range of 3-3000 ng/mL and with satisfactory stability. This method was also characterized with adequate intra- and inter-day precision and accuracy (within 12%) in the quality control samples, and with high selectivity and less matrix effect observed. Total running time was only 1.5 min. This method has been successfully applied to a pilot FLC pharmacokinetic study after oral administration. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Development of an LC/MS/MS method in order to determine arctigenin in rat plasma: its application to a pharmacokinetic study.

PubMed

Zou, Quanfei; Gu, Yuan; Lu, Rong; Zhang, Tiejun; Zhao, Guang-Rong; Liu, Changxiao; Si, Duanyun

2013-09-01

In this study, a simple and sensitive LC/MS/MS method was developed and validated for the determination of arctigenin in rat plasma. The MS detection was performed using multiple reaction monitoring at the transitions of m/z 373.2 → 137.3 for arctigenin and m/z 187.1 → 131.0 for psoralen (internal standard) with a Turbo IonSpray electrospray in positive mode. The calibration curves fitted a good linear relationship over the concentration range of 0.2-500 ng/mL. It was found that arctigenin is not stable enough at both room temperature and -80 °C unless mixed with methanol before storage. The validated LC/MS/MS method was successfully applied for the pharmacokinetic study of arctigenin in rats. After intravenous injection of 0.3 mg/kg arctigenin injection to rats, the maximum concentration, half-life and area under the concentration-time curve were 323 ± 65.2 ng/mL, 0.830 ± 0.166 and 81.0 ± 22.1 h ng/mL, respectively. Copyright © 2013 John Wiley & Sons, Ltd.

Early visual responses predict conscious face perception within and between subjects during binocular rivalry

PubMed Central

Sandberg, Kristian; Bahrami, Bahador; Kanai, Ryota; Barnes, Gareth Robert; Overgaard, Morten; Rees, Geraint

2014-01-01

Previous studies indicate that conscious face perception may be related to neural activity in a large time window around 170-800ms after stimulus presentation, yet in the majority of these studies changes in conscious experience are confounded with changes in physical stimulation. Using multivariate classification on MEG data recorded when participants reported changes in conscious perception evoked by binocular rivalry between a face and a grating, we showed that only MEG signals in the 120-320ms time range, peaking at the M170 around 180ms and the P2m at around 260ms, reliably predicted conscious experience. Conscious perception could not only be decoded significantly better than chance from the sensors that showed the largest average difference, as previous studies suggest, but also from patterns of activity across groups of occipital sensors that individually were unable to predict perception better than chance. Additionally, source space analyses showed that sources in the early and late visual system predicted conscious perception more accurately than frontal and parietal sites, although conscious perception could also be decoded there. Finally, the patterns of neural activity associated with conscious face perception generalized from one participant to another around the times of maximum prediction accuracy. Our work thus demonstrates that the neural correlates of particular conscious contents (here, faces) are highly consistent in time and space within individuals and that these correlates are shared to some extent between individuals. PMID:23281780

Elasticity-based determination of isovolumetric phases in the human heart

PubMed Central

2010-01-01

Background/Motivation To directly determine isovolumetric cardiac time intervals by magnetic resonance elastography (MRE) using the magnitude of the complex signal for deducing morphological information combined with the phase of the complex signal for tension-relaxation measurements. Methods Thirty-five healthy volunteers and 11 patients with relaxation abnormalities were subjected to transthoracic wave stimulation using vibrations of approximately 25 Hz. A k-space-segmented, ECG-gated gradient-recalled echo steady-state sequence with a 500-Hz bipolar motion-encoding gradient was used for acquiring a series of 360 complex images of a short-axis view of the heart at a frame rate of less than 5.2 ms. Magnitude images were employed for measuring the cross-sectional area of the left ventricle, while phase images were used for analyzing the amplitudes of the externally induced waves. The delay between the decrease in amplitude and onset of ventricular contraction was determined in all subjects and assigned to the time of isovolumetric tension. Conversely, the delay between the increase in wave amplitude and ventricular dilatation was used for measuring the time of isovolumetric elasticity relaxation. Results Wave amplitudes decreased during systole and increased during diastole. The variation in wave amplitude occurred ahead of morphological changes. In healthy volunteers the time of isovolumetric elasticity relaxation was 75 ± 31 ms, which is significantly shorter than the time of isovolumetric tension of 136 ± 36 ms (P < 0.01). In patients with relaxation abnormalities (mild diastolic dysfunction, n = 11) isovolumetric elasticity relaxation was significantly prolonged, with 133 ± 57 ms (P < 0.01), whereas isovolumetric tension time was in the range of healthy controls (161 ± 45 ms; P = 0.053). Conclusion The complex MRE signal conveys complementary information on cardiac morphology and elasticity, which can be combined for directly measuring isovolumetric tension and elasticity relaxation in the human heart. PMID:20979648

Elasticity-based determination of isovolumetric phases in the human heart.

PubMed

Elgeti, Thomas; Beling, Mark; Hamm, Bernd; Braun, Jürgen; Sack, Ingolf

2010-10-27

BACKGROUND/MOTIVATION: To directly determine isovolumetric cardiac time intervals by magnetic resonance elastography (MRE) using the magnitude of the complex signal for deducing morphological information combined with the phase of the complex signal for tension-relaxation measurements. Thirty-five healthy volunteers and 11 patients with relaxation abnormalities were subjected to transthoracic wave stimulation using vibrations of approximately 25 Hz. A k-space-segmented, ECG-gated gradient-recalled echo steady-state sequence with a 500-Hz bipolar motion-encoding gradient was used for acquiring a series of 360 complex images of a short-axis view of the heart at a frame rate of less than 5.2 ms. Magnitude images were employed for measuring the cross-sectional area of the left ventricle, while phase images were used for analyzing the amplitudes of the externally induced waves. The delay between the decrease in amplitude and onset of ventricular contraction was determined in all subjects and assigned to the time of isovolumetric tension. Conversely, the delay between the increase in wave amplitude and ventricular dilatation was used for measuring the time of isovolumetric elasticity relaxation. Wave amplitudes decreased during systole and increased during diastole. The variation in wave amplitude occurred ahead of morphological changes. In healthy volunteers the time of isovolumetric elasticity relaxation was 75 ± 31 ms, which is significantly shorter than the time of isovolumetric tension of 136 ± 36 ms (P < 0.01). In patients with relaxation abnormalities (mild diastolic dysfunction, n = 11) isovolumetric elasticity relaxation was significantly prolonged, with 133 ± 57 ms (P < 0.01), whereas isovolumetric tension time was in the range of healthy controls (161 ± 45 ms; P = 0.053). The complex MRE signal conveys complementary information on cardiac morphology and elasticity, which can be combined for directly measuring isovolumetric tension and elasticity relaxation in the human heart.

Identification of ozonation by-products of 4- and 5-methyl-1H-benzotriazole during the treatment of surface water to drinking water.

PubMed

Müller, Alexander; Weiss, Stefan C; Beisswenger, Judith; Leukhardt, H Georg; Schulz, Wolfgang; Seitz, Wolfram; Ruck, Wolfgang K L; Weber, Walter H

2012-03-01

During the treatment of surface water to drinking water, ozonation is often used for disinfection and to remove organic trace substances, whereby oxidation by-products can be formed. Here we use the example of tolyltriazole to describe an approach for identifying relevant oxidation by-products in the laboratory and subsequently detecting them in an industrial-scale process. The identification process involves ozonation experiments with pure substances at laboratory level (concentration range mg L(-1)). The reaction solutions from different ozone contact times were analyzed by high performance liquid chromatography - quadrupole time-of-flight mass spectrometry (HPLC-QTOF-MS) in full scan mode. Various approaches were used to detect the oxidation by-products: (i) target searches of postulated oxidation by-products, (ii) comparisons of chromatograms (e.g., UV/VIS) of the different samples, and (iii) color-coded abundance time courses (kinetic) of all detected compounds were illustrated in a kind of a heat map. MS/MS, H/D exchange, and derivatization experiments were used for structure elucidation for the detected by-product. Due to the low contaminant concentrations (ng L(-1)-range) of contaminants in the untreated water, the conversion of results from laboratory experiments to an industrial-scale required the use of HPLC-MS/MS with sample enrichment (e.g., solid phase extraction.) In cases where reference substances were not available or oxidation by-products without clear structures were detected, reaction solutions from laboratory experiments were used to optimize the analytical method to detect ng L(-1) in the samples of the industrial processes. We exemplarily demonstrated the effectiveness of the methodology with the industrial chemicals 4- and 5-methyl-1H-benzotriazole (4- and 5-MBT) as an example. Moreover, not only did we identify several oxidation by-products in the laboratory experiments tentatively, but also detected three of the eleven reaction products in the outlet of the full-scale ozonation unit. Copyright © 2011 Elsevier Ltd. All rights reserved.

Quantification of menadione from plasma and urine by a novel cysteamine-derivatization based UPLC-MS/MS method.

PubMed

Yuan, Teng-Fei; Wang, Shao-Ting; Li, Yan

2017-09-15

Menadione, as the crucial component of vitamin Ks, possessed significant nutritional and clinical values. However, there was still lack of favourable quantification strategies for it to date. For improvement, a novel cysteamine derivatization based UPLC-MS/MS method was presented in this work. The derivatizating reaction was proved non-toxic, easy-handling and high-efficient, which realized the MS detection of menadione under positive mode. Benefitting from the excellent sensitivity of the derivatizating product as well as the introduction of the stable isotope dilution technique, the quantification could be achieved in the range of 0.05-50.0ng/mL for plasma and urine matrixes with satisfied accuracy and precision. After analysis of the samples from healthy volunteers after oral administration of menadione sodium bisulfite tablets, the urinary free menadione was quantified for the very first time. We believe the progress in this work could largely promote the exploration of the metabolic mechanism of vitamin K in vivo. Copyright © 2017 Elsevier B.V. All rights reserved.

Investigation of the metabolism of substance P at the blood-brain barrier using LC-MS/MS.

PubMed

Chappa, Arvind K; Cooper, Joshua D; Audus, Kenneth L; Lunte, Susan M

2007-03-12

Substance P (SP) has been associated with pain and depression as well as neurodegenerative diseases. Many of these diverse actions of SP can potentially be attributed to SP metabolites generated at the blood-brain barrier (BBB). In this study, the metabolism of SP was investigated using an in vitro model of the BBB and LC-MS/MS. Substance P metabolism was found to be non-saturable in the concentration range of 100 nM to 10 microM, with approximately 70% of the peptide remaining intact after 5 h. The major metabolites of SP were identified by MS as 3-11 and 5-11. Two previously unreported metabolites, 5-11 and 6-11, were also found in our studies. Several additional minor SP metabolites, including 1-9 and 2-11, were also identified. A profile of the SP metabolites generated by the BBB over time was obtained. The results from the present study provide a better understanding of the role of the blood-brain barrier in the pharmacology of SP.

INVESTIGATION OF THE METABOLISM OF SUBSTANCE P AT THE BLOOD-BRAIN BARRIER USING LC-MS/MS

PubMed Central

Chappa, Arvind K.; Cooper, Joshua D.; Audus, Kenneth L.; Lunte, Susan M.

2007-01-01

Substance P (SP) has been associated with pain and depression as well as neurodegenerative diseases. Many of these diverse actions of SP can potentially be attributed to SP metabolites generated at the blood-brain barrier (BBB). In this study, the metabolism of SP was investigated using an in vitro model of the BBB and LC-MS/MS. Substance P metabolism was found to be non-saturable in the concentration range of 100 nM to 10 μM, with approximately 70% of the peptide remaining intact after 5 h. The major metabolites of SP were identified by MS as 3-11 and 5-11. Two previously unreported metabolites, 5-11 and 6-11, were also found in our studies. Several additional minor SP metabolites, including 1-9 and 2-11, were also identified. A profile of the SP metabolites generated by the BBB over time was obtained. The results from the present study provide us a better understanding of the role of the blood-brain barrier in the pharmacology of SP. PMID:17118606

Analysis of 100 pharmaceuticals and their degradates in water samples by liquid chromatography/quadrupole time-of-flight mass spectrometry.

PubMed

Ferrer, Imma; Thurman, E Michael

2012-10-12

A straightforward methodology for the chromatographic separation and accurate mass identification of 100 pharmaceuticals including some of their degradation products was developed using liquid chromatography/quadrupole time-of-flight mass spectrometry (LC/Q-TOF-MS). A table compiling the protonated or deprotonated exact masses for all compounds, as well as the exact mass of several fragment ions obtained by MS-MS is included. Excellent chromatographic separation was achieved by using 3.5 μm particle size columns and a slow and generic 30-min gradient. Isobaric and isomeric compounds (same nominal mass and same exact mass, respectively) were distinguished by various methods, including chromatography separation, MS-MS fragmentation, and isotopic signal identification. Method reporting limits of detection ranged from 1 to 1000 ng/L, after solid-phase extraction of 100mL aqueous samples. The methodology was successfully applied to the analysis of surface water impacted by wastewater effluent by identifying many of the pharmaceuticals and metabolites included in the list. Examples are given for some of the most unusual findings in environmental samples. This paper is meant to serve as a guide for those doing analysis of pharmaceuticals in environmental samples, by providing exact mass measurements of several well known, as well as newly identified and environmentally relevant pharmaceuticals in water samples. Copyright © 2012 Elsevier B.V. All rights reserved.

The evolution of the dust temperatures of galaxies in the SFR-M∗ plane up to z ∼ 2

NASA Astrophysics Data System (ADS)

Magnelli, B.; Lutz, D.; Saintonge, A.; Berta, S.; Santini, P.; Symeonidis, M.; Altieri, B.; Andreani, P.; Aussel, H.; Béthermin, M.; Bock, J.; Bongiovanni, A.; Cepa, J.; Cimatti, A.; Conley, A.; Daddi, E.; Elbaz, D.; Förster Schreiber, N. M.; Genzel, R.; Ivison, R. J.; Le Floc'h, E.; Magdis, G.; Maiolino, R.; Nordon, R.; Oliver, S. J.; Page, M.; Pérez García, A.; Poglitsch, A.; Popesso, P.; Pozzi, F.; Riguccini, L.; Rodighiero, G.; Rosario, D.; Roseboom, I.; Sanchez-Portal, M.; Scott, D.; Sturm, E.; Tacconi, L. J.; Valtchanov, I.; Wang, L.; Wuyts, S.

2014-01-01

We study the evolution of the dust temperature of galaxies in the SFR- M∗ plane up to z ~ 2 using far-infrared and submillimetre observations from the Herschel Space Observatory taken as part of the PACS Evolutionary Probe (PEP) and Herschel Multi-tiered Extragalactic Survey (HerMES) guaranteed time key programmes. Starting from a sample of galaxies with reliable star-formation rates (SFRs), stellar masses (M∗) and redshift estimates, we grid the SFR- M∗parameter space in several redshift ranges and estimate the mean dust temperature (Tdust) of each SFR-M∗ - z bin. Dust temperatures are inferred using the stacked far-infrared flux densities (100-500 μm) of our SFR-M∗ - z bins. At all redshifts, the dust temperature of galaxies smoothly increases with rest-frame infrared luminosities (LIR), specific SFRs (SSFR; i.e., SFR/M∗), and distances with respect to the main sequence (MS) of the SFR- M∗ plane (i.e., Δlog (SSFR)MS = log [SSFR(galaxy)/SSFRMS(M∗,z)]). The Tdust - SSFR and Tdust - Δlog (SSFR)MS correlations are statistically much more significant than the Tdust - LIR one. While the slopes of these three correlations are redshift-independent, their normalisations evolve smoothly from z = 0 and z ~ 2. We convert these results into a recipe to derive Tdust from SFR, M∗ and z, valid out to z ~ 2 and for the stellar mass and SFR range covered by our stacking analysis. The existence of a strong Tdust - Δlog (SSFR)MS correlation provides us with several pieces of information on the dust and gas content of galaxies. Firstly, the slope of the Tdust - Δlog (SSFR)MS correlation can be explained by the increase in the star-formation efficiency (SFE; SFR/Mgas) with Δlog (SSFR)MS as found locally by molecular gas studies. Secondly, at fixed Δlog (SSFR)MS, the constant dust temperature observed in galaxies probing wide ranges in SFR and M∗ can be explained by an increase or decrease in the number of star-forming regions with comparable SFE enclosed in them. And thirdly, at high redshift, the normalisation towards hotter dust temperature of the Tdust - Δlog (SSFR)MS correlation can be explained by the decrease in the metallicities of galaxies or by the increase in the SFE of MS galaxies. All these results support the hypothesis that the conditions prevailing in the star-forming regions of MS and far-above-MS galaxies are different. MS galaxies have star-forming regions with low SFEs and thus cold dust, while galaxies situated far above the MS seem to be in a starbursting phase characterised by star-forming regions with high SFEs and thus hot dust. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.Appendices are available in electronic form at http://www.aanda.org

A simple, rapid atmospheric pressure chemical ionization liquid chromatography tandem mass spectrometry method for the determination of 25-hydroxyvitamin D2 and D3.

PubMed

Garg, Uttam; Munar, Ada; Frazee, Clinton; Scott, David

2012-09-01

Vitamin D plays a vital role not only in bone health but also in pathophysiology of many other body functions. In recent years, there has been significant increase in testing of 25-hydroxyvitamin D (25-OH vitamin D), a marker of vitamin D deficiency. The most commonly used methods for the measurement of 25-OH vitamin D are immunoassays and liquid chromatography tandem mass spectrometry (LC-MS-MS). Since immunoassays suffer from inaccuracies and interferences, LC-MS-MS is a preferred method. In LC-MS-MS methods, 25-OH vitamin D is extracted from serum or plasma by solid-phase or liquid-phase extraction. Because these extraction methods are time consuming, we developed an easy method that uses simple protein precipitation followed by injection of the supernatant to LC-MS-MS. Several mass-to-charge (m/z) ratio transitions, including commonly used transitions based on water loss, were evaluated and several tube types were tested. The optimal transitions for 25-OH vitamin D2 and D3 were 395.5 > 269.5 and 383.4 > 257.3, respectively. The reportable range of the method was 1-100 ng/mL, and repeatability (within-run) and within-laboratory imprecision were <4% and <6%, respectively. The method agreed well with the solid-phase extraction methods. © 2012 Wiley Periodicals, Inc.

Information processing characteristics in subtypes of multiple sclerosis.

PubMed

De Sonneville, L M J; Boringa, J B; Reuling, I E W; Lazeron, R H C; Adèr, H J; Polman, C H

2002-01-01

The purpose of this study was to evaluate information processing characteristics in patients with multiple sclerosis (MS). We selected 53 patients with MS and 58 matched healthy controls. Using computerized tests, we investigated focused, divided, sustained attention, and executive function, and attempted to pinpoint deficits in attentional control to peripheral or central processing stages. The results substantiate the hypothesis that the slowing of attention-demanding (controlled) information processing underlying more complex cognitive skills is general, i.e. irrespective of type of controlled processing, with MS patients being 40% slower than controls. MS patients may suffer from focused, and divided and sustained attention deficits, as well as from compromised central processing stages, with secondary progressive (SP) patients showing the most extensive range of deficits, closely followed by primary progressive (PP) patients, while relapsing-remitting (RR) patients appear to be much less affected. General slowing appears to be highest in PP and SP type MS patients (50% slower) versus relapsing-remitting MS (24% slower). In contrast to most previous results, (complex) processing speed appeared to be robustly correlated with severity of MS as measured by the expanded disability status scale and with disease duration. Patients did much less differ in accuracy of processing from controls, suggesting the importance of using time strategies in planning everyday life and job activities to compensate for or alleviate MS-related speed handicaps. Copyright 2002 Elsevier Science Ltd.

Fast targeted analysis of 132 acidic and neutral drugs and poisons in whole blood using LC-MS/MS.

PubMed

Di Rago, Matthew; Saar, Eva; Rodda, Luke N; Turfus, Sophie; Kotsos, Alex; Gerostamoulos, Dimitri; Drummer, Olaf H

2014-10-01

The aim of this study was to develop an LC-MS/MS based screening technique that covers a broad range of acidic and neutral drugs and poisons by combining a small sample volume and efficient extraction technique with simple automated data processing. After protein precipitation of 100μL of whole blood, 132 common acidic and neutral drugs and poisons including non-steroidal anti-inflammatory drugs, barbiturates, anticonvulsants, antidiabetics, muscle relaxants, diuretics and superwarfarin rodenticides (47 quantitated, 85 reported as detected) were separated using a Shimadzu Prominence HPLC system with a C18 separation column (Kinetex XB-C18, 4.6mm×150mm, 5μm), using gradient elution with a mobile phase of 25mM ammonium acetate buffer (pH 7.5)/acetonitrile. The drugs were detected using an ABSciex(®) API 2000 LC-MS/MS system (ESI+ and -, MRM mode, two transitions per analyte). The method was fully validated in accordance with international guidelines. Quantification data obtained using one-point calibration compared favorably to that using multiple calibrants. The presented LC-MS/MS assay has proven to be applicable for determination of the analytes in blood. The fast and reliable extraction method combined with automated processing gives the opportunity for high throughput and fast turnaround times for forensic and clinical toxicology. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Reagent for Evaluating Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) Performance in Bottom-Up Proteomic Experiments.

PubMed

Beri, Joshua; Rosenblatt, Michael M; Strauss, Ethan; Urh, Marjeta; Bereman, Michael S

2015-12-01

We present a novel proteomic standard for assessing liquid chromatography-tandem mass spectrometry (LC-MS/MS) instrument performance, in terms of chromatographic reproducibility and dynamic range within a single LC-MS/MS injection. The peptide mixture standard consists of six peptides that were specifically synthesized to cover a wide range of hydrophobicities (grand average hydropathy (GRAVY) scores of -0.6 to 1.9). A combination of stable isotope labeled amino acids ((13)C and (15)N) were inserted to create five isotopologues. By combining these isotopologues at different ratios, they span four orders of magnitude within each distinct peptide sequence. Each peptide, from lightest to heaviest, increases in abundance by a factor of 10. We evaluate several metrics on our quadrupole orbitrap instrument using the 6 × 5 LC-MS/MS reference mixture spiked into a complex lysate background as a function of dynamic range, including mass measurement accuracy (MMA) and the linear range of quantitation of MS1 and parallel reaction monitoring experiments. Detection and linearity of the instrument routinely spanned three orders of magnitude across the gradient (500 fmol to 0.5 fmol on column) and no systematic trend was observed for MMA of targeted peptides as a function of abundance by analysis of variance analysis (p = 0.17). Detection and linearity of the fifth isotopologue (i.e., 0.05 fmol on column) was dependent on the peptide and instrument scan type (MS1 vs PRM). We foresee that this standard will serve as a powerful method to conduct both intra-instrument performance monitoring/evaluation, technology development, and inter-instrument comparisons.

Capillary Electrophoresis-Mass Spectrometry for the Analysis of Heparin Oligosaccharides and Low Molecular Weight Heparin.

PubMed

Sun, Xiaojun; Lin, Lei; Liu, Xinyue; Zhang, Fuming; Chi, Lianli; Xia, Qiangwei; Linhardt, Robert J

2016-02-02

Heparins, highly sulfated, linear polysaccharides also known as glycosaminoglycans, are among the most challenging biopolymers to analyze. Hyphenated techniques in conjunction with mass spectrometry (MS) offer rapid analysis of complex glycosaminoglycan mixtures, providing detailed structural and quantitative data. Previous analytical approaches have often relied on liquid chromatography (LC)-MS, and some have limitations including long separation times, low resolution of oligosaccharide mixtures, incompatibility of eluents, and often require oligosaccharide derivatization. This study examines the analysis of glycosaminoglycan oligosaccharides using a novel electrokinetic pump-based capillary electrophoresis (CE)-MS interface. CE separation and electrospray were optimized using a volatile ammonium bicarbonate electrolyte and a methanol-formic acid sheath fluid. The online analyses of highly sulfated heparin oligosaccharides, ranging from disaccharides to low molecular weight heparins, were performed within a 10 min time frame, offering an opportunity for higher-throughput analysis. Disaccharide compositional analysis as well as top-down analysis of low molecular weight heparin was demonstrated. Using normal polarity CE separation and positive-ion electrospray ionization MS, excellent run-to-run reproducibility (relative standard deviation of 3.6-5.1% for peak area and 0.2-0.4% for peak migration time) and sensitivity (limit of quantification of 2.0-5.9 ng/mL and limit of detection of 0.6-1.8 ng/mL) could be achieved.

Comparison of enzyme kinetics of warfarin analyzed by LC-MS/MS QTrap and differential mobility spectrometry.

PubMed

Shaik, Abdul Naveed; Grater, Richard; Lulla, Mukesh; Williams, David A; Gan, Lawrence L; Bohnert, Tonika; LeDuc, Barbara W

2016-01-01

Warfarin is an anticoagulant used in the treatment of thrombosis and thromboembolism. It is given as a racemic mixture of R and S enantiomers. These two enantiomers show differences in metabolism by CYPs: S-warfarin undergoes 7 hydroxylation by CYP2C9 and R-warfarin by CYP3A4 to form 10 hydroxy warfarin. In addition, warfarin is acted upon by different CYPs to form the minor metabolites 3'-hydroxy, 4'-hydroxy, 6-hydroxy, and 8-hydroxy warfarin. For analysis, separation of these metabolites is necessary since all have the same m/z ratio and similar fragmentation pattern. Enzyme kinetics for the formation of all of the six hydroxylated metabolites of warfarin from human liver microsomes were determined using an LC-MS/MS QTrap and LC-MS/MS with a differential mobility spectrometry (DMS) (SelexION™) interface to compare the kinetic parameters. These two methods were chosen to compare their selectivity and sensitivity. Substrate curves for 3'-OH, 4'-OH, 6-OH, 7-OH, 8-OH and 10-OH warfarin formation were generated to determine the kinetic parameters (Km and Vmax) in human liver microsomal preparations. The limit of quantitation (LOQ) for all the six hydroxylated metabolites of warfarin were in the range of 1-3nM using an LC-MS/MS QTrap method which had a run time of 22min. In contrast, the LOQ for all the six hydroxylated metabolites using DMS interface technology was 100nM with a run time of 2.8min. We compare these two MS methods and discuss the kinetics of metabolite formation for the metabolites generated from racemic warfarin. In addition, we show inhibition of major metabolic pathways of warfarin by sulfaphenazole and ketoconazole which are known specific inhibitors of CYP2C9 and CYP3A4 respectively. Copyright © 2015 Elsevier B.V. All rights reserved.

Biotransformation and metabolic profile of caudatin-2,6-dideoxy-3-O-methy-β-d-cymaropyranoside with human intestinal microflora by liquid chromatography quadrupole time-of-flight mass spectrometry.

PubMed

Zhang, Wei; Peng, Yun-ru; Ding, Yong-fang

2015-11-01

In our previous studies, caudatin-2,6-dideoxy-3-O-methy-β-d- cymaropyranoside (CDMC) was for the first time isolated from Cynanchum auriculatum Royle ex Wightand and was reported to possess a wide range of biological activities. However, the routes and metabolites of CDMC produced by intestinal bacteria are not well understood. In this study, ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) technique combined with Metabolynx(TM) software was applied to analyze metabolites of CDMC by human intestinal bacteria. The incubated samples collected for 48 h in an anaerobic incubator and extracted with ethyl acetate were analyzed by UPLC-Q-TOF-MS within 12 min. Eight metabolites were identified based on MS and MS/MS data. The results indicated that hydrolysis, hydrogenation, demethylation and hydroxylation were the major metabolic pathways of CDMC in vitro. Seven strains of bacteria including Bacillus sp. 46, Enterococcus sp. 30 and sp. 45, Escherichia sp. 49A, sp. 64, sp. 68 and sp. 75 were further identified using 16S rRNA gene sequencing owing to their relatively strong metabolic capacity toward CDMC. The present study provides important information about metabolic routes of CDMC and the roles of different intestinal bacteria in the metabolism of CDMC. Moreover, those metabolites might influence the biological effect of CDMC in vivo, which affects the clinical effects of this medicinal plant. Copyright © 2015 John Wiley & Sons, Ltd.

Importance of optimizing chromatographic conditions and mass spectrometric parameters for supercritical fluid chromatography/mass spectrometry.

PubMed

Fujito, Yuka; Hayakawa, Yoshihiro; Izumi, Yoshihiro; Bamba, Takeshi

2017-07-28

Supercritical fluid chromatography/mass spectrometry (SFC/MS) has great potential in high-throughput and the simultaneous analysis of a wide variety of compounds, and it has been widely used in recent years. The use of MS for detection provides the advantages of high sensitivity and high selectivity. However, the sensitivity of MS detection depends on the chromatographic conditions and MS parameters. Thus, optimization of MS parameters corresponding to the SFC condition is mandatory for maximizing performance when connecting SFC to MS. The aim of this study was to reveal a way to decide the optimum composition of the mobile phase and the flow rate of the make-up solvent for MS detection in a wide range of compounds. Additionally, we also showed the basic concept for determination of the optimum values of the MS parameters focusing on the MS detection sensitivity in SFC/MS analysis. To verify the versatility of these findings, a total of 441 pesticides with a wide polarity range (logP ow from -4.21 to 7.70) and pKa (acidic, neutral and basic). In this study, a new SFC-MS interface was used, which can transfer the entire volume of eluate into the MS by directly coupling the SFC with the MS. This enabled us to compare the sensitivity or optimum MS parameters for MS detection between LC/MS and SFC/MS for the same sample volume introduced into the MS. As a result, it was found that the optimum values of some MS parameters were completely different from those of LC/MS, and that SFC/MS-specific optimization of the analytical conditions is required. Lastly, we evaluated the sensitivity of SFC/MS using fully optimized analytical conditions. As a result, we confirmed that SFC/MS showed much higher sensitivity than LC/MS when the analytical conditions were fully optimized for SFC/MS; and the high sensitivity also increase the number of the compounds that can be detected with good repeatability in real sample analysis. This result indicates that SFC/MS has potential for practical use in the multiresidue analysis of a wide range of compounds that requires high sensitivity. Copyright © 2017 Elsevier B.V. All rights reserved.

On the life and death of satellite haloes

NASA Astrophysics Data System (ADS)

Taffoni, Giuliano; Mayer, Lucio; Colpi, Monica; Governato, Fabio

2003-05-01

We study the evolution of dark matter satellites orbiting inside more massive haloes using semi-analytical tools coupled with high-resolution N-body simulations. We select initial satellite sizes, masses, orbital energies, and eccentricities as predicted by hierarchical models of structure formation. Both the satellite (of initial mass Ms,0) and the main halo (of mass Mh) are described by a Navarro, Frenk & White density profile with various concentrations. We explore the interplay between dynamic friction and tidal mass loss/evaporation in determining the final fate of the satellite. We provide a user-friendly expression for the dynamic friction time-scale τdf,live and for the disruption time for a live (i.e. mass-losing) satellite. This can be easily implemented into existing semi-analytical models of galaxy formation improving considerably the way they describe the evolution of satellites. Massive satellites (Ms,0 > 0.1Mh) starting from typical cosmological orbits sink rapidly (irrespective of the initial circularity) toward the centre of the main halo where they merge after a time τdf,rig, as if they were rigid. Satellites of intermediate mass (0.01Mh < Ms,0 < 0.1Mh) suffer severe tidal mass losses as dynamic friction reduces their pericentre distance. In this case, mass loss increases substantially their decay time with respect to a rigid satellite. The final fate depends on the concentration of the satellite, cs, relative to that of the main halo, ch. Only in the unlikely case where cs/ch<~ 1 are satellites disrupted. In this mass range, τdf,live gives a measure of the merging time. Among the satellites whose orbits decay significantly, those that survive must have been moving preferentially on more circular orbits since the beginning as dynamical friction does not induce circularization. Lighter satellites (Ms,0 < 0.01Mh) do not suffer significant orbital decay and tidal mass loss stabilizes the orbit even further. Their orbits should map those at the time of entrance into the main halo. After more than a Hubble time satellites have masses Ms~ 1-10 per cent Ms,0, typically, implying Ms < 0.001Mh for the remnants. In a Milky-Way-like halo, light satellites should be present even after several orbital times with their baryonic components experimenting morphological changes due to tidal stirring. They coexist with the remnants of more massive satellites depleted in their dark matter content by the tidal field, which should move preferentially on tightly bound orbits.

Analysis of wastewater samples by direct combination of thin-film microextraction and desorption electrospray ionization mass spectrometry.

PubMed

Strittmatter, Nicole; Düring, Rolf-Alexander; Takáts, Zoltán

2012-09-07

An analysis method for aqueous samples by the direct combination of C18/SCX mixed mode thin-film microextraction (TFME) and desorption electrospray ionization mass spectrometry (DESI-MS) was developed. Both techniques make analytical workflow simpler and faster, hence the combination of the two techniques enables considerably shorter analysis time compared to the traditional liquid chromatography mass spectrometry (LC-MS) approach. The method was characterized using carbamazepine and triclosan as typical examples for pharmaceuticals and personal care product (PPCP) components which draw increasing attention as wastewater-derived environmental contaminants. Both model compounds were successfully detected in real wastewater samples and their concentrations determined using external calibration with isotope labeled standards. Effects of temperature, agitation, sample volume, and exposure time were investigated in the case of spiked aqueous samples. Results were compared to those of parallel HPLC-MS determinations and good agreement was found through a three orders of magnitude wide concentration range. Serious matrix effects were observed in treated wastewater, but lower limits of detection were still found to be in the low ng L(-1) range. Using an Orbitrap mass spectrometer, the technique was found to be ideal for screening purposes and led to the detection of various different PPCP components in wastewater treatment plant effluents, including beta-blockers, nonsteroidal anti-inflammatory drugs, and UV filters.

Interobserver agreement on Poser's and the new McDonald's diagnostic criteria for multiple sclerosis.

PubMed

Zipoli, V; Portaccio, E; Siracusa, G; Pracucci, G; Sorbi, S; Amato, M P

2003-10-01

We assessed the interobserver agreement on the diagnosis of multiple sclerosis (MS) in a study sample consisting of 41 MS (15 relapsing remitting, two secondary progressive, five primary progressive and 19 presenting their first clinical attack) and three non-MS cases. Clinical and paraclinical information was recorded in standardized forms. Four neurologists were asked to make a diagnosis using Poser's and McDonald's criteria and to assess MRI scans according to the McDonald's guidelines. In terms of the kappa statistic (kappa), we found a moderate agreement on the overall diagnosis using both Poser's and McDonald's criteria (kappa, respectively 0.57 and 0.52). As for distinct diagnostic categories, we observed a moderate to substantial agreement for the three McDonald categories (range of kappa values 0.49-0.64) and a fair to substantial agreement for the nine Poser categories (range of kappa values 0.37-0.67). Taking into account clinical information, the agreement on dissemination over time was substantially higher (kappa = 0.69) than that found on dissemination over space (kappa = 0.46). In contrast, for MRI assessment, the agreement for spatial dissemination was substantial (kappa = 0.74) compared with the fair agreement (kappa = 0.25) yielded by dissemination over time. The new McDonald's criteria yield a good overall diagnostic reliability, and compare favourably with Poser's classification in terms of agreement on distinct diagnostic categories.

A Variable Oscillator Underlies the Measurement of Time Intervals in the Rostral Medial Prefrontal Cortex during Classical Eyeblink Conditioning in Rabbits.

PubMed

Caro-Martín, C Rocío; Leal-Campanario, Rocío; Sánchez-Campusano, Raudel; Delgado-García, José M; Gruart, Agnès

2015-11-04

We were interested in determining whether rostral medial prefrontal cortex (rmPFC) neurons participate in the measurement of conditioned stimulus-unconditioned stimulus (CS-US) time intervals during classical eyeblink conditioning. Rabbits were conditioned with a delay paradigm consisting of a tone as CS. The CS started 50, 250, 500, 1000, or 2000 ms before and coterminated with an air puff (100 ms) directed at the cornea as the US. Eyelid movements were recorded with the magnetic search coil technique and the EMG activity of the orbicularis oculi muscle. Firing activities of rmPFC neurons were recorded across conditioning sessions. Reflex and conditioned eyelid responses presented a dominant oscillatory frequency of ≈12 Hz. The firing rate of each recorded neuron presented a single peak of activity with a frequency dependent on the CS-US interval (i.e., ≈12 Hz for 250 ms, ≈6 Hz for 500 ms, and≈3 Hz for 1000 ms). Interestingly, rmPFC neurons presented their dominant firing peaks at three precise times evenly distributed with respect to CS start and also depending on the duration of the CS-US interval (only for intervals of 250, 500, and 1000 ms). No significant neural responses were recorded at very short (50 ms) or long (2000 ms) CS-US intervals. rmPFC neurons seem not to encode the oscillatory properties characterizing conditioned eyelid responses in rabbits, but are probably involved in the determination of CS-US intervals of an intermediate range (250-1000 ms). We propose that a variable oscillator underlies the generation of working memories in rabbits. The way in which brains generate working memories (those used for the transient processing and storage of newly acquired information) is still an intriguing question. Here, we report that the firing activities of neurons located in the rostromedial prefrontal cortex recorded in alert behaving rabbits are controlled by a dynamic oscillator. This oscillator generated firing frequencies in a variable band of 3-12 Hz depending on the conditioned stimulus-unconditioned stimulus intervals (1 s, 500 ms, 250 ms) selected for classical eyeblink conditioning of behaving rabbits. Shorter (50 ms) and longer (2 s) intervals failed to activate the oscillator and prevented the acquisition of conditioned eyelid responses. This is an unexpected mechanism to generate sustained firing activities in neural circuits generating working memories. Copyright © 2015 the authors 0270-6474/15/3514809-13$15.00/0.

Generic DART-MS platform for monitoring the on-demand continuous-flow production of pharmaceuticals: Advancing the quantitative protocol for caffeates in microfluidic biocatalysis.

PubMed

Xu, Yan; Zhang, Dong-Yang; Meng, Xiang-Yun; Liu, Xi; Sheng, Sheng; Wu, Guo-Hua; Wang, Jun; Wu, Fu-An

2017-04-15

Today, continuous processing is regarded as an effective on-demand production technique of pharmaceuticals. Homemade microreactors packed with immobilized lipase under continuous-flow conditions were first applied to tailor the production of high-value caffeic acid phenethyl ester (CAPE) from methyl caffeate (MC) and 2-phenylethanol (PE) in cyclohexane via transesterification; however, this method is challenging due to the lack of a rapid platform for monitoring caffeates in microfluidic biocatalysis. The reactants were directly analyzed using Direct Analysis in Real Time Mass Spectrometry (DART-MS), and the corresponding ionization parameters were investigated. Special ions produced from MC (parent ion m/z 192.87 and product ion m/z 133.44) and CAPE (parent ion m/z 282.93 and product ion m/z 178.87) were determined using DART-MS 2 in the negative ion mode. The peak areas of the select reaction monitoring (SRM) signals were calculated to develop the standard curves for quantitative analyses of the concentration. Reasonable linear regression equations of MC and CAPE were obtained in the range of 3.125-50.000mg/L, with linear coefficients (R 2 ) of 0.9515 and 0.9973, limits of detection (LOD) of 0.005 and 0.003mg/L, limits of quantification (LOQ) of 0.02 and 0.01mg/L, and recovery ranges of 92.50-97.11% and 90.11-97.60%, respectively. The results using DART-MS 2 were in good agreement with those using conventional High-Performance Liquid Chromatography with a UV detector (HPLC-UV) and were successfully applied to monitor the kinetics constants and mass transfer coefficients in a continuous-flow packed bed microreactor. Thus, the DART-MS 2 method is an efficient tool for analyzing caffeates in microfluidic biocatalysis with limited sample preparation and short operating time. Copyright © 2017 Elsevier B.V. All rights reserved.

LOAPEX: The Long-Range Ocean Acoustic Propagation EXperiment

DTIC Science & Technology

2009-01-01

roughly 4200 m, the OBS/H packages at 5000 m received the LOAPEX transmissions. 4) Signal Processing : In general, signal processing for all receptions is...coherently in the time domain. To optimize processing , is based on the coherence time of the received signal and the resulting pro- cessing gain is . The...replica of the transmission. This process produces a triangular-shaped pulse with a time resolution of 1-b length, or 27 ms, and additional processing

Disability status, disease parameters, defense styles, and ego strength associated with psychiatric complications of multiple sclerosis.

PubMed

Hyphantis, Thomas N; Christou, Konstantinos; Kontoudaki, Stavroula; Mantas, Christos; Papamichael, George; Goulia, Panagiota; Konitsiotis, Spyros; Mavreas, Venetsanos

2008-01-01

The aim of the present study was to identify disease parameters, defensive styles and ego strength measurements associated with various forms of psychiatric complications in patients with multiple sclerosis (MS). Seventy-nine patients with MS participated in the study and 158 healthy subjects matched for age and sex served as controls. A wide range of clinical information was collected and the following self-report instruments were used: General Health Questionnaire, Symptom Distress Check List, Defense Style Questionnaire, MMPI Ego Strength Scale and Hostility and Direction of Hostility Questionnaire. The odds of being assessed with a psychiatric diagnosis upon interview were 6.7 times greater among patients compared to controls and 9.3 times greater among patients with recent-onset MS compared to patients with long-term disease. Psychiatric complications of MS were closely associated with age of the disease onset and the degree of disability due to MS. Additionally, higher rates of introverted hostility, adoption of maladaptive ego defenses and weakened ego strength were also closely associated with several forms of psychological distress, especially depressive symptoms. MS patients experience elevated symptoms of psychological distress, especially depressive symptoms, which are most closely associated with disease parameters. However, the crucial role of various personality traits such as ego defenses and hostility features in the psychiatric symptom formation also appear to contribute to the development of depressive symptoms. Clinicians involved in the clinical management of patients with MS should identify and modify treatment if these specific personality markers that indicate the exhaustion of the patient's resources to cope with the physical and psychological stress of the illness are present.

Validation of an enantioselective LC-MS/MS method to quantify enantiomers of (±)-OTX015 in mice plasma: Lack of in vivo inversion of (-)-OTX015 to its antipode.

PubMed

Balaji, Narayanan; Chinnapattu, Murugan; Dixit, Abhishek; Sahu, Promod; P S, Suresh; Mullangi, Ramesh

2017-04-01

A highly sensitive, specific and enantioselective assay has been validated for the quantitation of OTX015 enantiomers [(+)-OTX015 and (-)-OTX015] in mice plasma on LC-MS/MS-electrospray ionization as per regulatory guidelines. Protein precipitation was used to extract (±)-OTX015 enantiomers and internal standard (IS) from mice plasma. The active [(-)-OTX015] and inactive [(+)-OTX015] enantiomers were resolved on a Chiralpak-IA column using an isocratic mobile phase (0.2% ammonia/acetonitrile 20 : 80, v/v) at a flow rate of 1.2 mL/min. The total run time was 6.0 min. (+)-OTX015, (-)-OTX015 and IS eluted at 3.34, 4.08 and 4.77 min, respectively. The MS/MS ion transitions monitored were m/z 492 → 383 for OTX015 and m/z 457 → 401 for IS. The standard curves for OTX015 enantiomers were linear (r 2  > 0.998) in the concentration range 1.03-1030 ng/mL. The inter- and intraday precisions were in the range 2.20-13.3 and 8.03-12.1% and 3.80-14.4 and 8.97-13.6% for (+)-OTX015 and (-)-OTX015, respectively. Both the enantiomers were found to be stable in a battery of stability studies. This novel method has been applied to the study of stereoselective oral pharmacokinetics of (-)-OTX015 and unequivocally demonstrated that (-)-OTX015 does not undergo chiral inversion to its antipode in vivo in mice. Copyright © 2016 John Wiley & Sons, Ltd.

Determination of Sphingosine-1-Phosphate in Human Plasma Using Liquid Chromatography Coupled with Q-Tof Mass Spectrometry

PubMed Central

Egom, Emmanuel E.; Fitzgerald, Ross; Canning, Rebecca; Pharithi, Rebabonye B.; Murphy, Colin; Maher, Vincent

2017-01-01

Evidence suggests that high-density lipoprotein (HDL) components distinct from cholesterol, such as sphingosine-1-phosphate (S1P), may account for the anti-atherothrombotic effects attributed to this lipoprotein. The current method for the determination of plasma levels of S1P as well as levels associated with HDL particles is still cumbersome an assay method to be worldwide practical. Recently, a simplified protocol based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the sensitive and specific quantification of plasma levels of S1P with good accuracy has been reported. This work utilized a triple quadrupole (QqQ)-based LC-MS/MS system. Here we adapt that method for the determination of plasma levels of S1P using a quadrupole time of flight (Q-Tof) based LC-MS system. Calibration curves were linear in the range of 0.05 to 2 µM. The lower limit of quantification (LOQ) was 0.05 µM. The concentration of S1P in human plasma was determined to be 1 ± 0.09 µM (n = 6). The average accuracy over the stated range of the method was found to be 100 ± 5.9% with precision at the LOQ better than 10% when predicting the calibration standards. The concentration of plasma S1P in the prepared samples was stable for 24 h at room temperature. We have demonstrated the quantification of plasma S1P using Q-Tof based LC-MS with very good sensitivity, accuracy, and precision that can used for future studies in this field. PMID:28820460

Prediction beyond the borders: ERP indices of boundary extension-related error.

PubMed

Czigler, István; Intraub, Helene; Stefanics, Gábor

2013-01-01

Boundary extension (BE) is a rapidly occurring memory error in which participants incorrectly remember having seen beyond the boundaries of a view. However, behavioral data has provided no insight into how quickly after the onset of a test picture the effect is detected. To determine the time course of BE from neural responses we conducted a BE experiment while recording EEG. We exploited a diagnostic response asymmetry to mismatched views (a closer and wider view of the same scene) in which the same pair of views is rated as more similar when the closer item is shown first than vice versa. On each trial, a closer or wider view was presented for 250 ms followed by a 250-ms mask and either the identical view or a mismatched view. Boundary ratings replicated the typical asymmetry. We found a similar asymmetry in ERP responses in the 265-285 ms interval where the second member of the close-then-wide pairs evoked less negative responses at left parieto-temporal sites compared to the wide-then-close condition. We also found diagnostic ERP effects in the 500-560 ms range, where ERPs to wide-then-close pairs were more positive at centro-parietal sites than in the other three conditions, which is thought to be related to participants' confidence in their perceptual decision. The ERP effect in the 265-285 ms range suggests the falsely remembered region beyond the view-boundaries of S1 is rapidly available and impacts assessment of the test picture within the first 265 ms of viewing, suggesting that extrapolated scene structure may be computed rapidly enough to play a role in the integration of successive views during visual scanning.

Hematocrit-Independent Quantitation of Stimulants in Dried Blood Spots: Pipet versus Microfluidic-Based Volumetric Sampling Coupled with Automated Flow-Through Desorption and Online Solid Phase Extraction-LC-MS/MS Bioanalysis.

PubMed

Verplaetse, Ruth; Henion, Jack

2016-07-05

A workflow overcoming microsample collection issues and hematocrit (HCT)-related bias would facilitate more widespread use of dried blood spots (DBS). This report describes comparative results between the use of a pipet and a microfluidic-based sampling device for the creation of volumetric DBS. Both approaches were successfully coupled to HCT-independent, fully automated sample preparation and online liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) analysis allowing detection of five stimulants in finger prick blood. Reproducible, selective, accurate, and precise responses meeting generally accepted regulated bioanalysis guidelines were observed over the range of 5-1000 ng/mL whole blood. The applied heated flow-through solvent desorption of the entire spot and online solid phase extraction (SPE) procedure were unaffected by the blood's HCT value within the tested range of 28.0-61.5% HCT. Enhanced stability for mephedrone on DBS compared to liquid whole blood was observed. Finger prick blood samples were collected using both volumetric sampling approaches over a time course of 25 h after intake of a single oral dose of phentermine. A pharmacokinetic curve for the incurred phentermine was successfully produced using the described validated method. These results suggest that either volumetric sample collection method may be amenable to field-use followed by fully automated, HCT-independent DBS-SPE-LC-MS/MS bioanalysis for the quantitation of these representative controlled substances. Analytical data from DBS prepared with a pipet and microfluidic-based sampling devices were comparable, but the latter is easier to operate, making this approach more suitable for sample collection by unskilled persons.

Application of liquid-liquid microextraction for the effective separation and simultaneous determination of 11 pharmaceuticals in wastewater samples using HPLC-MS/MS.

PubMed

Diuzheva, Alina; Balogh, József; Jekő, József; Cziáky, Zoltán

2018-05-17

A dispersive liquid-liquid microextraction method for the simultaneous determination of 11 pharmaceuticals has been developed. The method is based on a microextraction procedure applied to wastewater samples from different regions of Hungary followed by high performance liquid chromatography with mass spectrometry. The effect of the nature of the extractant, dispersive solvent, different additives and extraction time were examined on the extraction efficiently of the dispersive liquid-liquid microextraction method. Under optimal conditions, the linearity for determining the pharmaceuticals was in the range of 1-500 ng mL -1 , with the correlation coefficients ranging from 0.9922 to 0.9995. The limits of detection and limits of quantification were in the range 0.31-6.65 and 0.93-22.18 ng mL -1 , respectively. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

The nature of genetic susceptibility to multiple sclerosis: constraining the possibilities.

PubMed

Goodin, Douglas S

2016-04-27

Epidemiological observations regarding certain population-wide parameters (e.g., disease-prevalence, recurrence-risk in relatives, gender predilections, and the distribution of common genetic-variants) place important constraints on the possibilities for the genetic-basis underlying susceptibility to multiple sclerosis (MS). Using very broad range-estimates for the different population-wide epidemiological parameters, a mathematical model can help elucidate the nature and the magnitude of these constraints. For MS no more than 8.5 % of the population can possibly be in the "genetically-susceptible" subset (defined as having a life-time MS-probability at least as high as the overall population average). Indeed, the expected MS-probability for this subset is more than 12 times that for every other person of the population who is not in this subset. Moreover, provided that those genetically susceptible persons (genotypes), who carry the well-established MS susceptibility allele (DRB1*1501), are equally or more likely to get MS than those susceptible persons, who don't carry this allele, then at least 84 % of MS-cases must come from this "genetically susceptible" subset. Finally, because men, compared to women, are at least as likely (and possibly more likely) to be susceptible, it can be demonstrated that women are more responsive to the environmental factors that are involved in MS-pathogenesis (whatever these are) and, thus, susceptible women are more likely actually to develop MS than susceptible men. Finally, in contrast to genetic susceptibility, more than 70 % of men (and likely also women) must have an environmental experience (including all of the necessary factors), which is sufficient to produce MS in a susceptible individual. As a result, because of these constraints, it is possible to distinguish two classes of persons, indicating either that MS can be caused by two fundamentally different pathophysiological mechanisms or that the large majority of the population is at no risk of the developing this disease regardless of their environmental experience. Moreover, although environmental-factors would play a critical role in both mechanisms (if both exist), there is no reason to expect that these factors are the same (or even similar) between the two.

Carbon nanodots as a matrix for the analysis of low-molecular-weight molecules in both positive- and negative-ion matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and quantification of glucose and uric acid in real samples.

PubMed

Chen, Suming; Zheng, Huzhi; Wang, Jianing; Hou, Jian; He, Qing; Liu, Huihui; Xiong, Caiqiao; Kong, Xianglei; Nie, Zongxiu

2013-07-16

Carbon nanodots were applied for the first time as a new matrix for the analysis of low-molecular-weight compounds by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) in both positive- and negative-ion modes. A wide range of small molecules including amino acids, peptides, fatty acids, as well as β-agonists and neutral oligosaccharides were analyzed by MALDI MS with carbon nanodots as the matrix, and the lowest 0.2 fmol limits-of-detection were obtained for octadecanoic acid. Clear sodium and potassium adducts and deprotonated signals were produced in positive- and negative-ion modes. Furthermore, the glucose and uric acid in real samples were quantitatively determined by the internal standard method with the linear range of 0.5-9 mM and 0.1-1.8 mM (R(2) > 0.999), respectively. This work gives new insight into the application of carbon nanodots and provides a general approach for rapid analysis of low-molecular-weight compounds.

Masked Priming Effects in Aphasia: Evidence for Altered Automatic Spreading Activation

PubMed Central

Silkes, JoAnn P.; Rogers, Margaret A.

2015-01-01

Purpose Previous research has suggested that impairments of automatic spreading activation may underlie some aphasic language deficits. This study further investigated the status of automatic spreading activation in individuals with aphasia as compared with typical adults. Method Participants were 21 individuals with aphasia (12 fluent, 9 non-fluent) and 31 typical adults. Reaction time data were collected on a lexical decision task with masked repetition primes, assessed at 11 different interstimulus intervals (ISIs). Masked primes were used to assess automatic spreading activation without the confound of conscious processing. The various ISIs were used to assess the time to onset, and duration, of priming effects. Results The control group showed maximal priming in the 200 ms ISI condition, with significant priming at a range of ISIs surrounding that peak. Participants with both fluent and non-fluent aphasia showed maximal priming effects in the 250 ms ISI condition, and primed across a smaller range of ISIs than the control group. Conclusions Results suggest that individuals with aphasia have slowed automatic spreading activation, and impaired maintenance of activation over time, regardless of fluency classification. These findings have implications for understanding aphasic language impairment and for development of aphasia treatments designed directly address automatic language processes. PMID:22411281

Masked priming effects in aphasia: evidence of altered automatic spreading activation.

PubMed

Silkes, JoAnn P; Rogers, Margaret A

2012-12-01

Previous research has suggested that impairments of automatic spreading activation may underlie some aphasic language deficits. The current study further investigated the status of automatic spreading activation in individuals with aphasia as compared with typical adults. Participants were 21 individuals with aphasia (12 fluent, 9 nonfluent) and 31 typical adults. Reaction time data were collected on a lexical decision task with masked repetition primes, assessed at 11 different interstimulus intervals (ISIs). Masked primes were used to assess automatic spreading activation without the confound of conscious processing. The various ISIs were used to assess the time to onset and duration of priming effects. The control group showed maximal priming in the 200-ms ISI condition, with significant priming at a range of ISIs surrounding that peak. Participants with both fluent and nonfluent aphasia showed maximal priming effects in the 250-ms ISI condition and primed across a smaller range of ISIs than did the control group. Results suggest that individuals with aphasia have slowed automatic spreading activation and impaired maintenance of activation over time, regardless of fluency classification. These findings have implications for understanding aphasic language impairment and for development of aphasia treatments designed to directly address automatic language processes.

Two Aspects of Activation: Arousal and Subjective Significance – Behavioral and Event-Related Potential Correlates Investigated by Means of a Modified Emotional Stroop Task

PubMed Central

Imbir, Kamil; Spustek, Tomasz; Bernatowicz, Gabriela; Duda, Joanna; Żygierewicz, Jarosław

2017-01-01

The arousal level of words presented in a Stroop task was found to affect their interference on the required naming of the words’ color. Based on a dual-processes approach, we propose that there are two aspects to activation: arousal and subjective significance. Arousal is crucial for automatic processing. Subjective significance is specific to controlled processing. Based on this conceptual model, we predicted that arousal would enhance interference in a Stroop task, as attention would be allocated to the meaning of the inhibited word. High subjective significance should have the opposite effect, i.e., it should enhance the controlled and explicit part of Stroop task processing, which is color naming. We found that response latencies were modulated by the interaction between the arousal and subjective significance levels of words. The longest reaction times were observed for highly arousing words of medium subjective significance level. Arousal shaped event related potentials in the 150–290 ms time range, while effects of subjective significance were found for 50–150, 150–290, and 290–530 ms time ranges. PMID:29311872

12-bit 32 channel 500 MS/s low-latency ADC for particle accelerators real-time control

NASA Astrophysics Data System (ADS)

Karnitski, Anton; Baranauskas, Dalius; Zelenin, Denis; Baranauskas, Gytis; Zhankevich, Alexander; Gill, Chris

2017-09-01

Particle beam control systems require real-time low latency digital feedback with high linearity and dynamic range. Densely packed electronic systems employ high performance multichannel digitizers causing excessive heat dissipation. Therefore, low power dissipation is another critical requirement for these digitizers. A described 12-bit 500 MS/s ADC employs a sub-ranging architecture based on a merged sample & hold circuit, a residue C-DAC and a shared 6-bit flash core ADC. The core ADC provides a sequential coarse and fine digitization featuring a latency of two clock cycles. The ADC is implemented in a 28 nm CMOS process and consumes 4 mW of power per channel from a 0.9 V supply (interfacing and peripheral circuits are excluded). Reduced power consumption and small on-chip area permits the implementation of 32 ADC channels on a 10.7 mm2 chip. The ADC includes a JESD204B standard compliant output data interface operated at the 7.5 Gbps/ch rate. To minimize the data interface related time latency, a special feature permitting to bypass the JESD204B interface is built in. DoE Phase I Award Number: DE-SC0017213.

PHIBSS: Unified Scaling Relations of Gas Depletion Time and Molecular Gas Fractions

NASA Astrophysics Data System (ADS)

Tacconi, L. J.; Genzel, R.; Saintonge, A.; Combes, F.; García-Burillo, S.; Neri, R.; Bolatto, A.; Contini, T.; Förster Schreiber, N. M.; Lilly, S.; Lutz, D.; Wuyts, S.; Accurso, G.; Boissier, J.; Boone, F.; Bouché, N.; Bournaud, F.; Burkert, A.; Carollo, M.; Cooper, M.; Cox, P.; Feruglio, C.; Freundlich, J.; Herrera-Camus, R.; Juneau, S.; Lippa, M.; Naab, T.; Renzini, A.; Salome, P.; Sternberg, A.; Tadaki, K.; Übler, H.; Walter, F.; Weiner, B.; Weiss, A.

2018-02-01

This paper provides an update of our previous scaling relations between galaxy-integrated molecular gas masses, stellar masses, and star formation rates (SFRs), in the framework of the star formation main sequence (MS), with the main goal of testing for possible systematic effects. For this purpose our new study combines three independent methods of determining molecular gas masses from CO line fluxes, far-infrared dust spectral energy distributions, and ∼1 mm dust photometry, in a large sample of 1444 star-forming galaxies between z = 0 and 4. The sample covers the stellar mass range log(M */M ⊙) = 9.0–11.8, and SFRs relative to that on the MS, δMS = SFR/SFR(MS), from 10‑1.3 to 102.2. Our most important finding is that all data sets, despite the different techniques and analysis methods used, follow the same scaling trends, once method-to-method zero-point offsets are minimized and uncertainties are properly taken into account. The molecular gas depletion time t depl, defined as the ratio of molecular gas mass to SFR, scales as (1 + z)‑0.6 × (δMS)‑0.44 and is only weakly dependent on stellar mass. The ratio of molecular to stellar mass μ gas depends on (1+z{)}2.5× {(δ {MS})}0.52× {({M}* )}-0.36, which tracks the evolution of the specific SFR. The redshift dependence of μ gas requires a curvature term, as may the mass dependences of t depl and μ gas. We find no or only weak correlations of t depl and μ gas with optical size R or surface density once one removes the above scalings, but we caution that optical sizes may not be appropriate for the high gas and dust columns at high z. Based on observations of an IRAM Legacy Program carried out with the NOEMA, operated by the Institute for Radio Astronomy in the Millimetre Range (IRAM), which is funded by a partnership of INSU/CNRS (France), MPG (Germany), and IGN (Spain).

Development and validation of a rapid turboflow LC-MS/MS method for the quantification of LSD and 2-oxo-3-hydroxy LSD in serum and urine samples of emergency toxicological cases.

PubMed

Dolder, Patrick C; Liechti, Matthias E; Rentsch, Katharina M

2015-02-01

Lysergic acid diethylamide (LSD) is a widely used recreational drug. The aim of the present study is to develop a quantitative turboflow LC-MS/MS method that can be used for rapid quantification of LSD and its main metabolite 2-oxo-3-hydroxy LSD (O-H-LSD) in serum and urine in emergency toxicological cases without time-consuming extraction steps. The method was developed on an ion-trap LC-MS/MS instrument coupled to a turbulent-flow extraction system. The validation data showed no significant matrix effects and no ion suppression has been observed in serum and urine. Mean intraday accuracy and precision for LSD were 101 and 6.84%, in urine samples and 97.40 and 5.89% in serum, respectively. For O-H-LSD, the respective values were 97.50 and 4.99% in urine and 107 and 4.70% in serum. Mean interday accuracy and precision for LSD were 100 and 8.26% in urine and 101 and 6.56% in serum, respectively. For O-H-LSD, the respective values were 101 and 8.11% in urine and 99.8 and 8.35% in serum, respectively. The lower limit of quantification for LSD was determined to be 0.1 ng/ml. LSD concentrations in serum were expected to be up to 8 ng/ml. 2-Oxo-3-hydroxy LSD concentrations in urine up to 250 ng/ml. The new method was accurate and precise in the range of expected serum and urine concentrations in patients with a suspected LSD intoxication. Until now, the method has been applied in five cases with suspected LSD intoxication where the intake of the drug has been verified four times with LSD concentrations in serum in the range of 1.80-14.70 ng/ml and once with a LSD concentration of 1.25 ng/ml in urine. In serum of two patients, the O-H-LSD concentration was determined to be 0.99 and 0.45 ng/ml. In the urine of a third patient, the O-H-LSD concentration was 9.70 ng/ml.

Quantification of 2'-deoxy-2'-β-fluoro-4'-azidocytidine in rat and dog plasma using liquid chromatography-quadrupole time-of-flight and liquid chromatography-triple quadrupole mass spectrometry: Application to bioavailability and pharmacokinetic studies.

PubMed

Peng, Youmei; Cheng, Tiefeng; Dong, Lihong; Zhang, Yuhai; Chen, Xiaojing; Jiang, Jinhua; Zhang, Jingmin; Guo, Xiaohe; Guo, Mintong; Chang, Junbiao; Wang, Qingduan

2014-09-01

2'-Deoxy-2'-β-fluoro-4'-azidocytidine (FNC) is a novel pyrimidine analog that inhibits not only the replication of the hepatitis B virus (HBV), hepatitis C virus (HCV) and HIV but also the replication of lamivudine-resistant HBV, 4'-azidocytidine or 2'-β-methylcytidine-resistant HCV, and nucleoside reverse-transcriptase inhibitor-resistant HIV variants. The present study was undertaken to evaluate the absolute oral bioavailability of FNC in rats and the pharmacokinetic properties of FNC after intragastric administration of single and multiple doses in rats and dogs. A sensitive high-performance liquid chromatography tandem quadrupole time-of-flight mass spectrometry (HPLC/Q-TOF MS) method and a reliable high-performance liquid chromatography tandem triple quadrupole mass spectrometry (HPLC/QqQ MS/MS) method were established for the determination of FNC in the rat and dog plasmas, respectively. The sample preparation involved a protein-precipitation method with methanol after the addition of lamivudine as an internal standard. FNC was analyzed by LC using a YMC-Pack Pro C18 column (150mm×4.6mm, 3μm) with methanol (containing 0.3% formic acid): 10mM ammonium acetate (containing 0.3% formic acid, pH 2.8) (35:65, v/v) as the mobile phase. Both mass spectrometers were equipped with an electrospray ionization interface in the positive-ion mode. The linear range was from 2.00 to 2000.00ngmL(-1) in rat plasma and 0.50 to 400.00ngmL(-1) in dog plasma. The intraday and interday precision were less than 10.55%, and the accuracy was in the range of -5.86 to 5.13%. The mean recoveries were greater than 82.70% and 82.97% for FNC and IS, respectively. The HPLC/Q-TOF MS and HPLC/QqQ MS/MS methods were both successfully applied in the pharmacokinetic studies of FNC in rats and dogs. Copyright © 2014 Elsevier B.V. All rights reserved.

Simultaneous quantitation of delamanid (OPC-67683) and its eight metabolites in human plasma using UHPLC-MS/MS.

PubMed

Meng, Min; Smith, Benjamin; Johnston, Brad; Carter, Spencer; Brisson, Jerry; Roth, Sharin E

2015-10-01

Delamanid (OPC-67683) is a novel nitro-dihydroimidazo-oxazole derivative that is being developed by Otsuka Pharmaceutical Co., Ltd., Japan (referred to as Otsuka hereafter) for the treatment of tuberculosis (TB). An ultra-high performance liquid chromatographic-tandem mass spectrometry (UHPLC-MS/MS) method has been developed and validated for the determination of OPC-67683 and its eight metabolites, DM-6704, DM-6705, DM-6706, DM-6717, DM-6718, DM-6720, DM-6721 and DM-6722 in human plasma to support regulated clinical development. During method development several technical challenges such as poor chromatography, separation of structural isomers, conversion of the analytes, instability in matrix and long cycle time were encountered and overcome. A protein precipitation extraction (PPE) was used to extract plasma samples (50μL) and the resulting extracts were analyzed using reversed phase UHPLC-MS/MS with a electrospray (ESI) and selected reaction monitoring (SRM). The method was fully validated over the calibration curve range of 1.00-500ng/mL for all nine analytes with linear regression and 1/x(2) weighting according to regulatory guidance for bioanalysis. Based on three inter-day precision and accuracy runs, the between-run % relative standard deviation (RSD) for all nine analytes varied from 0.0 to 11.9% and the accuracy ranged from 92.7% to 102.5% of nominal at all quality controls (QC) concentrations, including the lower limit of quantitation (LLOQ) QC at 1.00ng/mL. The extraction recovery of OPC-67683 and its eight metabolites were above 95%. Various short term and long term solution and matrix stability were established including the stability of OPC-67683 and its eight metabolites in human plasma for 708 days at -70°C. Although this method has been used to support regulated clinic studies during the last decade and over ten thousand samples have been analyzed, this is the first time that the method development process and validation data have been published. Copyright © 2015 Elsevier B.V. All rights reserved.

Temporal modulation transfer functions in auditory receptor fibres of the locust ( Locusta migratoria L.).

PubMed

Prinz, P; Ronacher, B

2002-08-01

The temporal resolution of auditory receptors of locusts was investigated by applying noise stimuli with sinusoidal amplitude modulations and by computing temporal modulation transfer functions. These transfer functions showed mostly bandpass characteristics, which are rarely found in other species at the level of receptors. From the upper cut-off frequencies of the modulation transfer functions the minimum integration times were calculated. Minimum integration times showed no significant correlation to the receptor spike rates but depended strongly on the body temperature. At 20 degrees C the average minimum integration time was 1.7 ms, dropping to 0.95 ms at 30 degrees C. The values found in this study correspond well to the range of minimum integration times found in birds and mammals. Gap detection is another standard paradigm to investigate temporal resolution. In locusts and other grasshoppers application of this paradigm yielded values of the minimum detectable gap widths that are approximately twice as large than the minimum integration times reported here.

Multi-residue method for determination of 58 pesticides, pharmaceuticals and personal care products in water using solvent demulsification dispersive liquid-liquid microextraction combined with liquid chromatography-tandem mass spectrometry.

PubMed

Caldas, Sergiane Souza; Rombaldi, Caroline; Arias, Jean Lucas de Oliveira; Marube, Liziane Cardoso; Primel, Ednei Gilberto

2016-01-01

A rapid and efficient sample pretreatment using solvent-based de-emulsification dispersive liquid-liquid microextraction (SD-DLLME) coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) was studied for the extraction of 58 pharmaceuticals and personal care products (PPCPs) and pesticides from water samples. Type and volume of extraction and disperser solvents, pH, salt addition, amount of salt and type of demulsification solvent were evaluated. Limits of quantification (LOQ) in the range from 0.0125 to 1.25 µg L(-1) were reached, and linearity was in the range from the LOQ of each compound to 25 μg L(-1). Recoveries ranged from 60% to 120% for 84% of the compounds, with relative standard deviations lower than 29%. The proposed method demonstrated, for the first time, that sample preparation by SD-DLLME with determination by LC-MS/MS can be successfully used for the simultaneous extraction of 32 pesticides and 26 PPCPs from water samples. The entire procedure, including the extraction of 58 organic compounds from the aqueous sample solution and the breaking up of the emulsion after extraction with water, rather than with an organic solvent, was environmentally friendly. In addition, this technique was less expensive and faster than traditional techniques. Finally, the analytical method under study was successfully applied to the analysis of all 58 pesticides and PPCPs in surface water samples. Copyright © 2015 Elsevier B.V. All rights reserved.

Quantification of mevalonate-5-phosphate using UPLC-MS/MS for determination of mevalonate kinase activity.

PubMed

Reitzle, Lukas; Maier, Barbara; Stojanov, Silvia; Teupser, Daniel; Muntau, Ania C; Vogeser, Michael; Gersting, Søren W

2015-08-01

Mevalonate kinase deficiency, a rare autosomal recessive autoinflammatory disease, is caused by mutations in the MVK gene encoding mevalonate kinase (MK). MK catalyzes the phosphorylation of mevalonic acid to mevalonate-5-phosphate (MVAP) in the pathway of isoprenoid and sterol synthesis. The disease phenotype correlates with residual activity ranging from <0.5% for mevalonic aciduria to 1-7% for the milder hyperimmunoglobulinemia D and periodic fever syndrome (HIDS). Hence, assessment of loss-of-function requires high accuracy measurements. We describe a method using isotope dilution UPLC-MS/MS for precise and sensitive determination of MK activity. Wild-type MK and the variant V261A, which is associated with HIDS, were recombinantly expressed in Escherichia coli. Enzyme activity was determined by formation of MVAP over time quantified by isotope dilution UPLC-MS/MS. The method was validated according to the FDA Guidance for Bioanalytical Method Validation. Sensitivity for detection of MAVP by UPLC-MS/MS was improved by derivatization with butanol-HCl (LLOQ, 5.0 fmol) and the method was linear from 0.5 to 250 μmol/L (R(2) > 0.99) with a precision of ≥ 89% and an accuracy of ± 2.7%. The imprecision of the activity assay, including the enzymatic reaction and the UPLC-MS/MS quantification, was 8.3%. The variant V261A showed a significantly decreased activity of 53.1%. Accurate determination of MK activity was enabled by sensitive and reproducible detection of MVAP using UPLC-MS/MS. The novel method may improve molecular characterization of MVK mutations, provide robust genotype-phenotype correlations, and accelerate compound screening for drug candidates restoring variant MK activity. Copyright © 2015 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.

A comparison between DART-MS and DSA-MS in the forensic analysis of writing inks.

PubMed

Drury, Nicholas; Ramotowski, Robert; Moini, Mehdi

2018-05-23

Ambient ionization mass spectrometry is gaining momentum in forensic science laboratories because of its high speed of analysis, minimal sample preparation, and information-rich results. One such application of ambient ionization methodology includes the analysis of writing inks from questioned documents where colorants of interest may not be soluble in common solvents, rendering thin layer chromatography (TLC) and separation-mass spectrometry methods such as LC/MS (-MS) impractical. Ambient ionization mass spectrometry uses a variety of ionization techniques such as penning ionization in Direct Analysis in Real Time (DART), and atmospheric pressure chemical ionization in Direct Sample Analysis (DSA), and electrospray ionization in Desorption Electrospray Ionization (DESI). In this manuscript, two of the commonly used ambient ionization techniques are compared: Perkin Elmer DSA-MS and IonSense DART in conjunction with a JEOL AccuTOF MS. Both technologies were equally successful in analyzing writing inks and produced similar spectra. DSA-MS produced less background signal likely because of its closed source configuration; however, the open source configuration of DART-MS provided more flexibility for sample positioning for optimum sensitivity and thereby allowing smaller piece of paper containing writing ink to be analyzed. Under these conditions, the minimum sample required for DART-MS was 1mm strokes of ink on paper, whereas DSA-MS required a minimum of 3mm. Moreover, both techniques showed comparable repeatability. Evaluation of the analytical figures of merit, including sensitivity, linear dynamic range, and repeatability, for DSA-MS and DART-MS analysis is provided. To the forensic context of the technique, DART-MS was applied to the analysis of United States Secret Service ink samples directly on a sampling mesh, and the results were compared with DSA-MS of the same inks on paper. Unlike analysis using separation mass spectrometry, which requires sample preparation, both DART-MS and DSA-MS successfully analyzed writing inks with minimal sample preparation. Copyright © 2018 Elsevier B.V. All rights reserved.

Design, implementation and multisite evaluation of a system suitability protocol for the quantitative assessment of instrument performance in liquid chromatography-multiple reaction monitoring-MS (LC-MRM-MS).

PubMed

Abbatiello, Susan E; Mani, D R; Schilling, Birgit; Maclean, Brendan; Zimmerman, Lisa J; Feng, Xingdong; Cusack, Michael P; Sedransk, Nell; Hall, Steven C; Addona, Terri; Allen, Simon; Dodder, Nathan G; Ghosh, Mousumi; Held, Jason M; Hedrick, Victoria; Inerowicz, H Dorota; Jackson, Angela; Keshishian, Hasmik; Kim, Jong Won; Lyssand, John S; Riley, C Paige; Rudnick, Paul; Sadowski, Pawel; Shaddox, Kent; Smith, Derek; Tomazela, Daniela; Wahlander, Asa; Waldemarson, Sofia; Whitwell, Corbin A; You, Jinsam; Zhang, Shucha; Kinsinger, Christopher R; Mesri, Mehdi; Rodriguez, Henry; Borchers, Christoph H; Buck, Charles; Fisher, Susan J; Gibson, Bradford W; Liebler, Daniel; Maccoss, Michael; Neubert, Thomas A; Paulovich, Amanda; Regnier, Fred; Skates, Steven J; Tempst, Paul; Wang, Mu; Carr, Steven A

2013-09-01

Multiple reaction monitoring (MRM) mass spectrometry coupled with stable isotope dilution (SID) and liquid chromatography (LC) is increasingly used in biological and clinical studies for precise and reproducible quantification of peptides and proteins in complex sample matrices. Robust LC-SID-MRM-MS-based assays that can be replicated across laboratories and ultimately in clinical laboratory settings require standardized protocols to demonstrate that the analysis platforms are performing adequately. We developed a system suitability protocol (SSP), which employs a predigested mixture of six proteins, to facilitate performance evaluation of LC-SID-MRM-MS instrument platforms, configured with nanoflow-LC systems interfaced to triple quadrupole mass spectrometers. The SSP was designed for use with low multiplex analyses as well as high multiplex approaches when software-driven scheduling of data acquisition is required. Performance was assessed by monitoring of a range of chromatographic and mass spectrometric metrics including peak width, chromatographic resolution, peak capacity, and the variability in peak area and analyte retention time (RT) stability. The SSP, which was evaluated in 11 laboratories on a total of 15 different instruments, enabled early diagnoses of LC and MS anomalies that indicated suboptimal LC-MRM-MS performance. The observed range in variation of each of the metrics scrutinized serves to define the criteria for optimized LC-SID-MRM-MS platforms for routine use, with pass/fail criteria for system suitability performance measures defined as peak area coefficient of variation <0.15, peak width coefficient of variation <0.15, standard deviation of RT <0.15 min (9 s), and the RT drift <0.5min (30 s). The deleterious effect of a marginally performing LC-SID-MRM-MS system on the limit of quantification (LOQ) in targeted quantitative assays illustrates the use and need for a SSP to establish robust and reliable system performance. Use of a SSP helps to ensure that analyte quantification measurements can be replicated with good precision within and across multiple laboratories and should facilitate more widespread use of MRM-MS technology by the basic biomedical and clinical laboratory research communities.

Design, Implementation and Multisite Evaluation of a System Suitability Protocol for the Quantitative Assessment of Instrument Performance in Liquid Chromatography-Multiple Reaction Monitoring-MS (LC-MRM-MS)*

PubMed Central

Abbatiello, Susan E.; Mani, D. R.; Schilling, Birgit; MacLean, Brendan; Zimmerman, Lisa J.; Feng, Xingdong; Cusack, Michael P.; Sedransk, Nell; Hall, Steven C.; Addona, Terri; Allen, Simon; Dodder, Nathan G.; Ghosh, Mousumi; Held, Jason M.; Hedrick, Victoria; Inerowicz, H. Dorota; Jackson, Angela; Keshishian, Hasmik; Kim, Jong Won; Lyssand, John S.; Riley, C. Paige; Rudnick, Paul; Sadowski, Pawel; Shaddox, Kent; Smith, Derek; Tomazela, Daniela; Wahlander, Asa; Waldemarson, Sofia; Whitwell, Corbin A.; You, Jinsam; Zhang, Shucha; Kinsinger, Christopher R.; Mesri, Mehdi; Rodriguez, Henry; Borchers, Christoph H.; Buck, Charles; Fisher, Susan J.; Gibson, Bradford W.; Liebler, Daniel; MacCoss, Michael; Neubert, Thomas A.; Paulovich, Amanda; Regnier, Fred; Skates, Steven J.; Tempst, Paul; Wang, Mu; Carr, Steven A.

2013-01-01

Multiple reaction monitoring (MRM) mass spectrometry coupled with stable isotope dilution (SID) and liquid chromatography (LC) is increasingly used in biological and clinical studies for precise and reproducible quantification of peptides and proteins in complex sample matrices. Robust LC-SID-MRM-MS-based assays that can be replicated across laboratories and ultimately in clinical laboratory settings require standardized protocols to demonstrate that the analysis platforms are performing adequately. We developed a system suitability protocol (SSP), which employs a predigested mixture of six proteins, to facilitate performance evaluation of LC-SID-MRM-MS instrument platforms, configured with nanoflow-LC systems interfaced to triple quadrupole mass spectrometers. The SSP was designed for use with low multiplex analyses as well as high multiplex approaches when software-driven scheduling of data acquisition is required. Performance was assessed by monitoring of a range of chromatographic and mass spectrometric metrics including peak width, chromatographic resolution, peak capacity, and the variability in peak area and analyte retention time (RT) stability. The SSP, which was evaluated in 11 laboratories on a total of 15 different instruments, enabled early diagnoses of LC and MS anomalies that indicated suboptimal LC-MRM-MS performance. The observed range in variation of each of the metrics scrutinized serves to define the criteria for optimized LC-SID-MRM-MS platforms for routine use, with pass/fail criteria for system suitability performance measures defined as peak area coefficient of variation <0.15, peak width coefficient of variation <0.15, standard deviation of RT <0.15 min (9 s), and the RT drift <0.5min (30 s). The deleterious effect of a marginally performing LC-SID-MRM-MS system on the limit of quantification (LOQ) in targeted quantitative assays illustrates the use and need for a SSP to establish robust and reliable system performance. Use of a SSP helps to ensure that analyte quantification measurements can be replicated with good precision within and across multiple laboratories and should facilitate more widespread use of MRM-MS technology by the basic biomedical and clinical laboratory research communities. PMID:23689285

Mobile Phones and Multiple Sclerosis – A Nationwide Cohort Study in Denmark

PubMed Central

Harbo Poulsen, Aslak; Stenager, Egon; Johansen, Christoffer; Bentzen, Joan; Friis, Søren; Schüz, Joachim

2012-01-01

We investigated the risk of, prognosis of and symptoms of multiple sclerosis (MS) among all Danish residents who owned a mobile phone subscription before 1996. Using the Danish Multiple Sclerosis Registry and Civil Registration System, study subjects were followed up for MS through 2004. Poisson models were used to calculate incidence rate ratios (IRR, age range: 18–64 years) and mortality rate ratios (MRR, age range: 18+) and to compare presenting symptoms among subscribers and all non-subscribers. A total of 405 971 subscription holders accrued four million years of follow up, with men accounting for 86% of the observation time. Among subscription holding men, the IRR of MS was close to unity, overall as well as 13+ years after first subscription (IRR 1.02, 95% CI: 0.48–2.16). Among women, the IRR was 3.43 (95% CI: 0.86–13.72) 13+ years after first subscription, however, based on only two cases. Presenting symptoms of MS differed between subscribers and non-subscribers (p = 0.03), with slightly increased risk of diplopia in both genders (IRR: 1.38, 95% CI: 1.02–1.86), an increased risk of fatigue among women (IRR: 3.02, 95% CI: 1.45–6.28), and of optic neuritis among men (IRR: 1.38, 95% CI: 1.03–1.86). Overall the MRR was close to one (MRR: 0.91, 95%CI 0.70–1.19) among MS-patients with a subscription and although we observed some increased MRR estimates among women, these were based on small numbers. In conclusion, we found little evidence for a pronounced association between mobile phone use and risk of MS or mortality rate among MS patients. Symptoms of MS differed between subscribers and nonsubscribers for symptoms previously suggested to be associated with mobile phone use. This deserves further attention, as does the increased long-term risk of MS among female subscribers, although small numbers and lack of consistency between genders prevent causal interpretation. PMID:22558088

Synthesis and characterization of DNA nano-meso-microspheres as drug delivery carriers for intratumoral chemotherapy

NASA Astrophysics Data System (ADS)

Enriquez Schumacher, Iris Vanessa

Conventional cancer chemotherapy results in systemic toxicity which severely limits effectiveness and often adversely affects patient quality of life. There is a need to find new drugs and delivery methods for less toxic therapy. Previous studies concerning DNA complexing with chemotherapy drugs suggest unique opportunities for DNA as a mesosphere drug carrier. The overall objective of this research was devoted to the synthesis and evaluation of novel DNA-drug nano-mesospheres designed for localized chemotherapy via intratumoral injection. My research presents DNA nano-meso-microspheres (DNA-MS) that were prepared using a modified steric stabilization method originally developed in this lab for the preparation of albumin MS. DNA-MS were prepared with glutaraldehyde covalent crosslinking (genipin crosslinking was attempted) through the DNA base pairs. In addition, novel crosslinking of DNA-MS was demonstrated using chromium, gadolinium, or iron cations through the DNA phosphate groups. Covalent and ionic crosslinked DNA-MS syntheses yielded smooth and spherical particle morphologies with multimodal size distributions. Optimized DNA-MS syntheses produced particles with narrow and normal size distributions in the 50nm to 5mum diameter size range. In aqueous dispersions approximately 200% swelling was observed with dispersion stability for more than 48 hours. Typical process conditions included a 1550rpm initial mixing speed and particle filtration through 20mum filters to facilitate preparation. DNA-MS were in situ loaded during synthesis for the first time with mitoxantrone, 5-fluorouracil, and methotrexate. DNA-MS drug incorporation was 12%(w/w) for mitoxantrone, 9%(w/w) for methotrexate, and 5%(w/w) for 5-fluorouracil. In vitro drug release into phosphate buffered saline was observed for over 35 days by minimum sink release testing. The effect of gadolinium crosslink concentration on mitoxantrone release was evaluated at molar equivalences in the range of 20% to 120%. The most highly crosslinked DNA-MS exhibited the longest sustained release. The drug efficacy of mitoxantrone loaded DNA-MS was evaluated in vitro using a murine Lewis lung carcinoma cell line and a significant cytotoxic response was found at mitoxantrone doses as low as 1ppm. Drug release properties, DNA biodegradability, and observed cancer cell cytotoxicity of drug loaded DNA-MS suggest that they are appropriate for intratumoral chemotherapy evaluation aimed at improved and less toxic cancer therapy.

Design of a laser rangefinder for Martian terrain measurements. M.S. Thesis

NASA Technical Reports Server (NTRS)

Palumbo, D. L.

1973-01-01

Three methods for using a laser for rangefinding are discussed: optical focusing, the phase difference method, and timed pulse. For application on a Mars Rover, the timed pulse method proves to be the better choice in view of the requirements set down. This is made possible by pulse expansion techniques described in detail. Initial steps taken toward building the range finder are given, followed by a conclusion.

Clonazepam quantification in human plasma by high-performance liquid chromatography coupled with electrospray tandem mass spectrometry in a bioequivalence study.

PubMed

Cavedal, Luiz E; Mendes, Fabiana D; Domingues, Claudia C; Patni, Anil K; Monif, Tausif; Reyar, Simrit; Pereira, Alberto Dos S; Mendes, Gustavo D; De Nucci, Gilberto

2007-01-01

A rapid, sensitive and specific method for quantifying clonazepam in human plasma using diazepam as the internal standard (IS) is described. The analyte and the IS were extracted from plasma by liquid-liquid extraction using a hexane/diethylether (20 : 80, v/v) solution. The extracts were analysed by high-performance liquid chromatography coupled with electrospray tandem mass spectrometry (HPLC-MS-MS). Chromatography was performed on a Jones Genesis C8 4 microm analytical column (100 x 2.1 mm i.d.). The method had a chromatographic run time of 3.0 min and a linear calibration curve over the range 0.5-50 ng/ml (r2 > 0.9965). The limit of quantification was 0.5 ng/ml. This HPLC/MS/MS procedure was used to assess the bioequivalence of two clonazepam 2 mg tablet formulations (clonazepam test formulation from Ranbaxy Laboratories Ltd and Rivotril from Roche Laboratórios Ltda as standard reference formulation). Copyright 2006 John Wiley & Sons, Ltd.

Fourier transform (FT)-artifacts and power-function resolution filter in Fourier transform mass spectrometry.

PubMed

Kanawati, Basem; Bader, Theresa M; Wanczek, Karl-Peter; Li, Yan; Schmitt-Kopplin, Philippe

2017-10-15

Peak picking algorithms in mass spectrometry face the challenge of picking the correct signals from a mass spectrum. In some cases signal wiggles (side lobes) are also chosen in the produced mass list as if they were real signals. Constraints which are defined in such algorithms do not always guarantee wiggle-free accurate mass list generation out of raw mass spectra. This problem intensifies with acquisitions, which are accompanied by longer transients. Thus, the problem represents a contemporary issue, which propagates with modern high-memory digitizers and exists in both MS and MS/MS spectra. A solariX FTMS mass spectrometer with an Infinity ICR cell (Bruker Daltonics, Bremen, Germany) coupled to a 12 Tesla magnet (Magnex, UK) was used for the experimental study. Time-domain transients of several different data point lengths 512k, 1M, 2M, 4M, 8M were obtained and were Fourier-transformed to obtain frequency spectra which show the effect of the transient truncation on sinc wiggle developments in FT-ICR-MS. MATLAB simulations were also performed to investigate the origin of the Fourier transform (FT)-artifacts. A new filter has been developed to identify and remove FT-artifacts (sinc side lobes) from both frequency and mass spectra. The newly developed filter is based on distinguishing between the FWHM of the correct frequency/mass signals and the FWHM of their corresponding wiggles. The filter draws a reliable confidence limit of resolution range, within which a correct frequency/mass signal is identified. The filter is applicable over a wide mass range of metabolic interest (100-1200 amu). The origin of FT-artifacts due to time-domain transient truncations was thoroughly investigated both experimentally and by simulations in this study. A new solution for this problem with automatic recognition and elimination of these FT-artifacts (side lobes/wiggles) is provided, which is independent of any intensity thresholds, magnetic field strengths and time-domain transient lengths. Copyright © 2017 John Wiley & Sons, Ltd.

Design of experiments as a tool for LC-MS/MS method development for the trace analysis of the potentially genotoxic 4-dimethylaminopyridine impurity in glucocorticoids.

PubMed

Székely, Gy; Henriques, B; Gil, M; Ramos, A; Alvarez, C

2012-11-01

The present study reports on a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method development strategy supported by design of experiments (DoE) for the trace analysis of 4-dimethylaminopyridine (DMAP). The conventional approaches for development of LC-MS/MS methods are usually via trial and error, varying intentionally the experimental factors which is time consuming and interactions between experimental factors are not considered. The LC factors chosen for the DoE study include flow (F), gradient (G) and injection volume (V(inj)) while cone voltage (E(con)) and collision energy (E(col)) were chosen as MS parameters. All of the five factors were studied simultaneously. The method was optimized with respect to four responses: separation of peaks (Sep), peak area (A(peak)), length of the analysis (T) and the signal to noise ratio (S/N). A quadratic model, namely central composite face (CCF) featuring 29 runs was used instead of a less powerful linear model since the increase in the number of injections was insignificant. In order to determine the robustness of the method a new set of DoE experiments was carried out applying robustness around the optimal conditions was evaluated applying a fractional factorial of resolution III with 11 runs, wherein additional factors - such as column temperature and quadrupole resolution - were considered. The method utilizes a Phenomenex Gemini NX C-18 HPLC analytical column with electrospray ionization and a triple quadrupole mass detector in multiple reaction monitoring (MRM) mode, resulting in short analyses with a 10min runtime. Drawbacks of derivatization, namely incomplete reaction and time consuming sample preparation, have been avoided and the change from SIM to MRM mode resulted in increased sensitivity and lower LOQ. The DoE method development strategy led to a method allowing the trace analysis of DMAP at 0.5 ng/ml absolute concentration which corresponds to a 0.1 ppm limit of quantification in 5mg/ml mometasone furoate glucocorticoid. The obtained method was validated in a linear range of 0.1-10 ppm and presented a %RSD of 0.02% for system precision. Regarding DMAP recovery in mometasone furoate, spiked samples produced %recoveries between 83 and 113% in the range of 0.1-2 ppm. Copyright © 2012 Elsevier B.V. All rights reserved.

Zonal wind observations during a geomagnetic storm

NASA Technical Reports Server (NTRS)

Miller, N. J.; Spencer, N. W.

1986-01-01

In situ measurements taken by the Wind and Temperature Spectrometer (WATS) onboard the Dynamics Explorer 2 spacecraft during a geomagnetic storm display zonal wind velocities that are reduced in the corotational direction as the storm intensifies. The data were taken within the altitudes 275 to 475 km in the dusk local time sector equatorward of the auroral region. Characteristic variations in the value of the Dst index of horizontal geomagnetic field strength are used to monitor the storm evolution. The detected global rise in atmospheric gas temperature indicates the development of thermospheric heating. Concurrent with that heating, reductions in corotational wind velocities were measured equatorward of the auroral region. Just after the sudden commencement, while thermospheric heating is intense in both hemispheres, eastward wind velocities in the northern hemisphere show reductions ranging from 500 m/s over high latitudes to 30 m/s over the geomagnetic equator. After 10 hours storm time, while northern thermospheric heating is diminishing, wind velocity reductions, distinct from those initially observed, begin to develop over southern latitudes. In the latter case, velocity reductions range from 300 m/s over the highest southern latitudes to 150 m/s over the geomagnetic equator and extend into the Northern Hemisphere. The observations highlight the interhemispheric asymmetry in the development of storm effects detected as enhanced gas temperatures and reduced eastward wind velocities. Zonal wind reductions over high latitudes can be attributed to the storm induced equatorward spread of westward polar cap plasma convection and the resulting plasma-neutral collisions. However, those collisions are less significant over low latitudes; so zonal wind reductions over low latitudes must be attributed to an equatorward extension of a thermospheric circulation pattern disrupted by high latitude collisions between neutrals transported via eastward winds and ions convecting westward.

Development and Application of an MSALL-Based Approach for the Quantitative Analysis of Linear Polyethylene Glycols in Rat Plasma by Liquid Chromatography Triple-Quadrupole/Time-of-Flight Mass Spectrometry.

PubMed

Zhou, Xiaotong; Meng, Xiangjun; Cheng, Longmei; Su, Chong; Sun, Yantong; Sun, Lingxia; Tang, Zhaohui; Fawcett, John Paul; Yang, Yan; Gu, Jingkai

2017-05-16

Polyethylene glycols (PEGs) are synthetic polymers composed of repeating ethylene oxide subunits. They display excellent biocompatibility and are widely used as pharmaceutical excipients. To fully understand the biological fate of PEGs requires accurate and sensitive analytical methods for their quantitation. Application of conventional liquid chromatography-tandem mass spectrometry (LC-MS/MS) is difficult because PEGs have polydisperse molecular weights (MWs) and tend to produce multicharged ions in-source resulting in innumerable precursor ions. As a result, multiple reaction monitoring (MRM) fails to scan all ion pairs so that information on the fate of unselected ions is missed. This Article addresses this problem by application of liquid chromatography-triple-quadrupole/time-of-flight mass spectrometry (LC-Q-TOF MS) based on the MS ALL technique. This technique performs information-independent acquisition by allowing all PEG precursor ions to enter the collision cell (Q2). In-quadrupole collision-induced dissociation (CID) in Q2 then effectively generates several fragments from all PEGs due to the high collision energy (CE). A particular PEG product ion (m/z 133.08592) was found to be common to all linear PEGs and allowed their total quantitation in rat plasma with high sensitivity, excellent linearity and reproducibility. Assay validation showed the method was linear for all linear PEGs over the concentration range 0.05-5.0 μg/mL. The assay was successfully applied to the pharmacokinetic study in rat involving intravenous administration of linear PEG 600, PEG 4000, and PEG 20000. It is anticipated the method will have wide ranging applications and stimulate the development of assays for other pharmaceutical polymers in the future.

Neuropsychological, balance, and mobility risk factors for falls in people with multiple sclerosis: a prospective cohort study.

PubMed

Hoang, Phu D; Cameron, Michelle H; Gandevia, Simon C; Lord, Stephen R

2014-03-01

To determine whether impaired performance in a range of vision, proprioception, neuropsychological, balance, and mobility tests and pain and fatigue are associated with falls in people with multiple sclerosis (PwMS). Prospective cohort study with 6-month follow-up. A multiple sclerosis (MS) physiotherapy clinic. Community-dwelling people (N=210; age range, 21-74y) with MS (Disease Steps 0-5). Not applicable. Incidence of falls during 6 months' follow-up. In the 6-month follow-up period, 83 participants (39.7%) experienced no falls, 57 (27.3%) fell once or twice, and 69 (33.0%) fell 3 or more times. Frequent falling (≥3) was associated with increased postural sway (eyes open and closed), poor leaning balance (as assessed with the coordinated stability task), slow choice stepping reaction time, reduced walking speed, reduced executive functioning (as assessed with the difference between Trail Making Test Part B and Trail Making Test Part A), reduced fine motor control (performance on the 9-Hole Peg Test [9-HPT]), and reported leg pain. Increased sway with the eyes closed, poor coordinated stability, and reduced performance in the 9-HPT were identified as variables that significantly and independently discriminated between frequent fallers and nonfrequent fallers (model χ(2)3=30.1, P<.001). The area under the receiver operating characteristic curve for this model was .712 (95% confidence interval, .638-.785). The study reveals important balance, coordination, and cognitive determinants of falls in PwMS. These should assist the development of effective strategies for prevention of falls in this high-risk group. Copyright © 2014 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Quantitative determination of mogroside V in rat plasma by LC-MS/MS and its application to a pharmacokinetic study.

PubMed

Yan, Huiyu; Tao, Lina; Qu, Xiaoyu; Zhou, Liting; Zhang, Sixi

2018-05-01

Mogroside V is the most abundant (approximately 0.50%) cucurbitane-type triterpene glycoside in Siraitia grosvenorii and exhibits significant antitussive, expectorant, anti-carcinogenic, and anti-inflammatory effects. A sensitive, robust and selective liquid chromatography tandem with mass spectrometry (LC-MS/MS) was developed and validated for the determination and pharmacokinetic investigation of mogroside V in rat plasma. Samples were prepared through an one-step deproteinization procedure with 250 µL of methanol to a 75-µL plasma sample. Plasma samples were effectively separated on a Shiseido Capcell Pak UG120 C18 column (2.0 × 50mm, 3.0µm) using a mobile phase consisting of methanol: water (60:40, v/v) with an isocratic elution program. The running time for each sample was 7.0 min and the elution times of mogroside V and IS were 2.0 and 4.8 min, respectively. The detection relied on a triple-quadrupole tandem with mass spectrometer equipped with negative-ion electrospray ionization interface by selected-reaction monitoring (SRM) of the transitions at m/z 1285.6 → 1123.7 for mogroside V and m/z 1089.6 → 649.6 for IS. The calibration curve was linear over the range of 96.0-96000ng/mL with a limit of quantitation (LOQ) of 96.0ng/mL. Intra-day and inter-day precisions were both <10.1%. Mean recovery and matrix effect of mogroside V in plasma were in the range of 91.3-95.7% and 98.2-105.0%, respectively. This method was successfully applied in the pharmacokinetic study of mogroside V after intravenous or intraperitoneal administration of 1.12mg/kg mogroside V in rats.

A rapid MCM-41 dispersive micro-solid phase extraction coupled with LC/MS/MS for quantification of ketoconazole and voriconazole in biological fluids.

PubMed

Yahaya, Noorfatimah; Sanagi, Mohd Marsin; Abd Aziz, Noorizan; Wan Ibrahim, Wan Aini; Nur, Hadi; Loh, Saw Hong; Kamaruzaman, Sazlinda

2017-02-01

A rapid dispersive micro-solid phase extraction (D-μ-SPE) combined with LC/MS/MS method was developed and validated for the determination of ketoconazole and voriconazole in human urine and plasma samples. Synthesized mesoporous silica MCM-41 was used as sorbent in d-μ-SPE of the azole compounds from biological fluids. Important D-μ-SPE parameters, namely type desorption solvent, extraction time, sample pH, salt addition, desorption time, amount of sorbent and sample volume were optimized. Liquid chromatographic separations were carried out on a Zorbax SB-C 18 column (2.1 × 100 mm, 3.5 μm), using a mobile phase of acetonitrile-0.05% formic acid in 5 mm ammonium acetate buffer (70:30, v/v). A triple quadrupole mass spectrometer with positive ionization mode was used for the determination of target analytes. Under the optimized conditions, the calibration curves showed good linearity in the range of 0.1-10,000 μg/L with satisfactory limit of detection (≤0.06 μg/L) and limit of quantitation (≤0.3 μg/L). The proposed method also showed acceptable intra- and inter-day precisions for ketoconazole and voriconazole from urine and human plasma with RSD ≤16.5% and good relative recoveries in the range 84.3-114.8%. The MCM-41-D-μ-SPE method proved to be rapid and simple and requires a small volume of organic solvent (200 μL); thus it is advantageous for routine drug analysis. Copyright © 2016 John Wiley & Sons, Ltd.

A rapid method for the simultaneous determination of L-ascorbic acid and acetylsalicylic acid in aspirin C effervescent tablet by ultra performance liquid chromatography-tandem mass spectrometry

NASA Astrophysics Data System (ADS)

Wabaidur, Saikh Mohammad; Alothman, Zeid Abdullah; Khan, Mohammad Rizwan

2013-05-01

In present study, a rapid and sensitive method using ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was developed for the simultaneous determination of L-ascorbic acid and acetylsalicylic acid in aspirin C effervescent tablet. The optimum chromatographic separation was carried out on a reversed phase Waters® Acquity UPLC BEH C18 column (1.7 μm particle size, 100 mm × 2.1 mm ID) with an isocratic elution profile and mobile phase consisting of 0.1% formic acid in water and acetonitrile (75:25, v/v, pH 3.5) at flow rate of 0.5 mL min-1. The influences of mobile phase composition, flow rate and pH on chromatographic resolution were investigated. The total chromatographic analysis time was as short as 2 min with excellent resolution. Detection and quantification of the target compounds were carried out with a triple quadrupole mass spectrometer using negative electrospray ionization (ESI) and multiple reaction monitoring (MRM) modes. The performance of the method was evaluated and very low limits of detection less than 0.09 μg g-1, excellent coefficient correlation (r2 > 0.999) with liner range over a concentration range of 0.1-1.0 μg g-1 for both L-ascorbic acid and acetylsalicylic acid, and good intraday and interday precisions (relative standard deviations (R.S.D.) <3%), were obtained. Comparison of system performance with traditional liquid chromatography-photo diode array detector (HPLC-PDA) was made with respect to analysis time, sensitivity, linearity and precisions. The proposed UPLC-MS/MS method was found to be reproducible and appropriate for quantitative analysis of L-ascorbic acid and acetylsalicylic acid in aspirin C effervescent tablet.

Automated solid-phase extraction-liquid chromatography-tandem mass spectrometry analysis of 6-acetylmorphine in human urine specimens: application for a high-throughput urine analysis laboratory.

PubMed

Robandt, P V; Bui, H M; Scancella, J M; Klette, K L

2010-10-01

An automated solid-phase extraction-liquid chromatography- tandem mass spectrometry (SPE-LC-MS-MS) method using the Spark Holland Symbiosis Pharma SPE-LC coupled to a Waters Quattro Micro MS-MS was developed for the analysis of 6-acetylmorphine (6-AM) in human urine specimens. The method was linear (R² = 0.9983) to 100 ng/mL, with no carryover at 200 ng/mL. Limits of quantification and detection were found to be 2 ng/mL. Interrun precision calculated as percent coefficient of variation (%CV) and evaluated by analyzing five specimens at 10 ng/mL over nine batches (n = 45) was 3.6%. Intrarun precision evaluated from 0 to 100 ng/mL ranged from 1.0 to 4.4%CV. Other opioids (codeine, morphine, oxycodone, oxymorphone, hydromorphone, hydrocodone, and norcodeine) did not interfere in the detection, quantification, or chromatography of 6-AM or the deuterated internal standard. The quantified values for 41 authentic human urine specimens previously found to contain 6-AM by a validated gas chromatography (GC)-MS method were compared to those obtained by the SPE-LC-MS-MS method. The SPE-LC-MS-MS procedure eliminates the human factors of specimen handling, extraction, and derivatization, thereby reducing labor costs and rework resulting from human error or technique issues. The time required for extraction and analysis was reduced by approximately 50% when compared to a validated 6-AM procedure using manual SPE and GC-MS analysis.

Multicenter Evaluation of the Vitek MS Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry System for Identification of Gram-Positive Aerobic Bacteria

PubMed Central

Burnham, Carey-Ann D.; Bythrow, Maureen; Garner, Omai B.; Ginocchio, Christine C.; Jennemann, Rebecca; Lewinski, Michael A.; Manji, Ryhana; Mochon, A. Brian; Procop, Gary W.; Richter, Sandra S.; Sercia, Linda; Westblade, Lars F.; Ferraro, Mary Jane; Branda, John A.

2013-01-01

Matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF) is gaining momentum as a tool for bacterial identification in the clinical microbiology laboratory. Compared with conventional methods, this technology can more readily and conveniently identify a wide range of organisms. Here, we report the findings from a multicenter study to evaluate the Vitek MS v2.0 system (bioMérieux, Inc.) for the identification of aerobic Gram-positive bacteria. A total of 1,146 unique isolates, representing 13 genera and 42 species, were analyzed, and results were compared to those obtained by nucleic acid sequence-based identification as the reference method. For 1,063 of 1,146 isolates (92.8%), the Vitek MS provided a single identification that was accurate to the species level. For an additional 31 isolates (2.7%), multiple possible identifications were provided, all correct at the genus level. Mixed-genus or single-choice incorrect identifications were provided for 18 isolates (1.6%). Although no identification was obtained for 33 isolates (2.9%), there was no specific bacterial species for which the Vitek MS consistently failed to provide identification. In a subset of 463 isolates representing commonly encountered important pathogens, 95% were accurately identified to the species level and there were no misidentifications. Also, in all but one instance, the Vitek MS correctly differentiated Streptococcus pneumoniae from other viridans group streptococci. The findings demonstrate that the Vitek MS system is highly accurate for the identification of Gram-positive aerobic bacteria in the clinical laboratory setting. PMID:23658261

Spinal manipulation force and duration affect vertebral movement and neuromuscular responses.

PubMed

Colloca, Christopher J; Keller, Tony S; Harrison, Deed E; Moore, Robert J; Gunzburg, Robert; Harrison, Donald D

2006-03-01

Previous study in human subjects has documented biomechanical and neurophysiological responses to impulsive spinal manipulative thrusts, but very little is known about the neuromechanical effects of varying thrust force-time profiles. Ten adolescent Merino sheep were anesthetized and posteroanterior mechanical thrusts were applied to the L3 spinous process using a computer-controlled, mechanical testing apparatus. Three variable pulse durations (10, 100, 200 ms, force = 80 N) and three variable force amplitudes (20, 40, 60 N, pulse duration = 100 ms) were examined for their effect on lumbar motion response (L3 displacement, L1, L2 acceleration) and normalized multifidus electromyographic response (L3, L4) using a repeated measures analysis of variance. Increasing L3 posteroanterior force amplitude resulted in a fourfold linear increase in L3 posteroanterior vertebral displacement (p < 0.001) and adjacent segment (L1, L2) posteroanterior acceleration response (p < 0.001). L3 displacement was linearly correlated (p < 0.001) to the acceleration response over the 20-80 N force range (100 ms). At constant force, 10 ms thrusts resulted in nearly fivefold lower L3 displacements and significantly increased segmental (L2) acceleration responses compared to the 100 ms (19%, p = 0.005) and 200 ms (16%, p = 0.023) thrusts. Normalized electromyographic responses increased linearly with increasing force amplitude at higher amplitudes and were appreciably affected by mechanical excitation pulse duration. Changes in the biomechanical and neuromuscular response of the ovine lumbar spine were observed in response to changes in the force-time characteristics of the spinal manipulative thrusts and may be an underlying mechanism in related clinical outcomes.

Immunosuppressant therapeutic drug monitoring by LC-MS/MS: workflow optimization through automated processing of whole blood samples.

PubMed

Marinova, Mariela; Artusi, Carlo; Brugnolo, Laura; Antonelli, Giorgia; Zaninotto, Martina; Plebani, Mario

2013-11-01

Although, due to its high specificity and sensitivity, LC-MS/MS is an efficient technique for the routine determination of immunosuppressants in whole blood, it involves time-consuming manual sample preparation. The aim of the present study was therefore to develop an automated sample-preparation protocol for the quantification of sirolimus, everolimus and tacrolimus by LC-MS/MS using a liquid handling platform. Six-level commercially available blood calibrators were used for assay development, while four quality control materials and three blood samples from patients under immunosuppressant treatment were employed for the evaluation of imprecision. Barcode reading, sample re-suspension, transfer of whole blood samples into 96-well plates, addition of internal standard solution, mixing, and protein precipitation were performed with a liquid handling platform. After plate filtration, the deproteinised supernatants were submitted for SPE on-line. The only manual steps in the entire process were de-capping of the tubes, and transfer of the well plates to the HPLC autosampler. Calibration curves were linear throughout the selected ranges. The imprecision and accuracy data for all analytes were highly satisfactory. The agreement between the results obtained with manual and those obtained with automated sample preparation was optimal (n=390, r=0.96). In daily routine (100 patient samples) the typical overall total turnaround time was less than 6h. Our findings indicate that the proposed analytical system is suitable for routine analysis, since it is straightforward and precise. Furthermore, it incurs less manual workload and less risk of error in the quantification of whole blood immunosuppressant concentrations than conventional methods. © 2013.

Multicenter evaluation of the Vitek MS matrix-assisted laser desorption ionization-time of flight mass spectrometry system for identification of Gram-positive aerobic bacteria.

PubMed

Rychert, Jenna; Burnham, Carey-Ann D; Bythrow, Maureen; Garner, Omai B; Ginocchio, Christine C; Jennemann, Rebecca; Lewinski, Michael A; Manji, Ryhana; Mochon, A Brian; Procop, Gary W; Richter, Sandra S; Sercia, Linda; Westblade, Lars F; Ferraro, Mary Jane; Branda, John A

2013-07-01

Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF) is gaining momentum as a tool for bacterial identification in the clinical microbiology laboratory. Compared with conventional methods, this technology can more readily and conveniently identify a wide range of organisms. Here, we report the findings from a multicenter study to evaluate the Vitek MS v2.0 system (bioMérieux, Inc.) for the identification of aerobic Gram-positive bacteria. A total of 1,146 unique isolates, representing 13 genera and 42 species, were analyzed, and results were compared to those obtained by nucleic acid sequence-based identification as the reference method. For 1,063 of 1,146 isolates (92.8%), the Vitek MS provided a single identification that was accurate to the species level. For an additional 31 isolates (2.7%), multiple possible identifications were provided, all correct at the genus level. Mixed-genus or single-choice incorrect identifications were provided for 18 isolates (1.6%). Although no identification was obtained for 33 isolates (2.9%), there was no specific bacterial species for which the Vitek MS consistently failed to provide identification. In a subset of 463 isolates representing commonly encountered important pathogens, 95% were accurately identified to the species level and there were no misidentifications. Also, in all but one instance, the Vitek MS correctly differentiated Streptococcus pneumoniae from other viridans group streptococci. The findings demonstrate that the Vitek MS system is highly accurate for the identification of Gram-positive aerobic bacteria in the clinical laboratory setting.

Optical progression characteristics of an interesting natural downward bipolar lightning flash

NASA Astrophysics Data System (ADS)

Chen, Luwen; Lu, Weitao; Zhang, Yijun; Wang, Daohong

2015-01-01

high-speed cameras, Lightning Attachment Process Observation Systems, and fast and slow electrical antennas, we documented a downward bipolar lightning flash that contained one first positive stroke with a peak current of 142 kA and five subsequent negative strokes hitting on a 90 m tall structure on 29 July 2010 in Guangzhou City, China. All the six strokes propagated along the same viewed channel established by the first positive return stroke. The leader which preceded the positive return stroke propagated downward without any branches at a two-dimensional (2-D) speed of 2.5 × 106 m/s. An upward connecting leader with a length of about 80 m was observed in response to the downward positive leader. The 10-90% risetimes of the return strokes' optical pulses ranged from 2.2 µs to 3.2 µs, while the widths from the 10% wavefront to the 50% wave tail ranged from 56.5 µs to 83.1 µs, and the half peak widths ranged from 53.4 µs to 81.6 µs. All the return strokes exhibited similar speeds, ranging from 1.0 × 108 m/s to 1.3 × 108 m/s. Each of the return strokes was followed by a continuing current stage (CC). The first positive stroke CC lasted more than 150 ms, much larger than all the subsequent negative stroke CC, ranging from 13 ms to 70 ms.

Quantification of underivatised amino acids on dry blood spot, plasma, and urine by HPLC-ESI-MS/MS.

PubMed

Giordano, Giuseppe; Di Gangi, Iole Maria; Gucciardi, Antonina; Naturale, Mauro

2012-01-01

Enzyme deficiencies in amino acid (AA) metabolism affecting the levels of amino acids and their derivatives in physiological fluids may serve as diagnostically significant biomarkers for one or a group of metabolic disorders. Therefore, it is important to monitor a wide range of free amino acids simultaneously and to quantify them. This is time consuming if we use the classical methods and more than ever now that many laboratories have introduced Newborn Screening Programs for the semiquantitative analysis, detection, and quantification of some amino acids needed to be performed in a short time to reduce the rate of false positives.We have modified the stable isotope dilution HPLC-electrospray ionization (ESI)-MS/MS method previously described by Qu et al. (Anal Chem 74: 2034-2040, 2002) for a more rapid, robust, sensitive, and specific detection and quantification of underivatised amino acids. The modified method reduces the time of analysis to 10 min with very good reproducibility of retention times and a better separation of the metabolites and their isomers.The omission of the derivatization step allowed us to achieve some important advantages: fast and simple sample preparation and exclusion of artefacts and interferences. The use of this technique is highly sensitive, specific, and allows monitoring of 40 underivatized amino acids, including the key isomers and quantification of some of them, in order to cover many diagnostically important intermediates of metabolic pathways.We propose this HPLC-ESI-MS/MS method for underivatized amino acids as a support for the Newborn Screening as secondary test using the same dried blood spots for a more accurate and specific examination in case of suspected metabolic diseases. In this way, we avoid plasma collection from the patient as it normally occurs, reducing anxiety for the parents and further costs for analysis.The same method was validated and applied also to plasma and urine samples with good reproducibility, accuracy, and precision. The fast run time, feasibility of high sample throughput, and small amount of sample required make this method very suitable for routine analysis in the clinical setting.

STS-109 MS Linnehan on aft flight deck with laser rangefinder

NASA Image and Video Library

2002-03-03

STS109-346-011 (3 March 2002) --- Astronaut Richard M. Linnehan, STS-109 mission specialist, uses a laser ranging device designed to measure the range between two spacecraft. Linnehan positioned himself on the cabin's aft flight deck as the Space Shuttle Columbia approached the Hubble Space Telescope. A short time later, the STS-109 crew captured and latched down the giant telescope in the vehicle's cargo bay for several days of work on the Hubble.

Two-phase electromembrane extraction followed by gas chromatography-mass spectrometry analysis.

PubMed

Davarani, Saied Saeed Hosseiny; Morteza-Najarian, Amin; Nojavan, Saeed; Pourahadi, Ahmad; Abbassi, Mojtaba Beigzadeh

2013-02-01

A two-phase electromembrane extraction (EME) was developed and directly coupled with gas chromatography mass spectrometry (GC-MS) analysis. The proposed method was successfully applied to the simultaneous determination of imipramine, desipramine, citalopram and sertraline. The model compounds were extracted from neutral aqueous sample solutions into the organic phase filled in the lumen of the hollow fiber. This method was accomplished with 1-heptanol as organic phase, by means of 60 V applied voltage and with the extraction time of 15 min. Experiments reported recoveries in the range of 69-87% from 1.2 mL neutral sample solution. The compounds were quantified by GC-MS instrument, with acceptable linearity ranging from 1 to 500 ng mL(-1) (R(2) in the range of 0.989 to 0.998), and repeatability (RSD) ranging between 7.5 and 11.5% (n = 5). The estimated detection limits (S/N ratio of 3:1) were less than 0.25 ng mL(-1). This novel approach based on two-phase EME brought advantages such as simplicity, low-costing, low detection limit and fast extraction with a total analysis time less than 25 min. These experimental findings were highly interesting and demonstrated the possibility of solving ionic species in the organic phase at the presence of electrical potential. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Selecting the best tone-pip stimulus-envelope time for estimating an objective middle-latency response threshold for low- and middle-tone sensorineural hearing losses.

PubMed

Xu, Z M; De Vel, E; Vinck, B; Van Cauwenberge, P

1995-01-01

The effects of rise-fall and plateau times for the Pa component of the middle-latency response (MLR) were investigated in normally hearing subjects, and an objective MLR threshold was measured in patients with low- and middle-tone hearing losses, using a selected stimulus-envelope time. Our results showed that the stimulus-envelope time (the rise-fall time and plateau time groups) affected the Pa component of the MLR (quality was determined by the (chi 2-test and amplitude by the F-test). The 4-2-4 tone-pips produced good Pa quality by visual inspection. However, our data revealed no statistically significant Na-Pa amplitude differences between the two subgroups studied when comparing the 2- and 4-ms rise-fall times and the 0- and 2-ms plateau times. In contrast, Na-Pa became significantly smaller from the 4-ms to the 6-ms rise-fall time and from the 2-ms to the 4-ms plateau time (paired t-test). This result allowed us to select the 2- or 4-ms rise-fall time and the 0- or 2-ms plateau time without influencing amplitude. Analysis of the stimulus spectral characteristics demonstrated that a rise-fall time of at least 2ms could prevent spectral splatter and indicated that a stimulus with a 5-ms rise-fall time had a greater frequency-specificity than a stimulus of 2-ms rise-fall time. When considering the synchronous discharge and frequency-specificity of MLR, our findings show that a rise-fall time of four periods with a plateau of two periods is an acceptable compromise for estimating the objective MLR threshold.(ABSTRACT TRUNCATED AT 250 WORDS)

A Collaborative Study: Determination of Mycotoxins in Corn, Peanut Butter, and Wheat Flour Using Stable Isotope Dilution Assay (SIDA) and Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS).

PubMed

Zhang, Kai; Schaab, Matthew R; Southwood, Gavin; Tor, Elizabeth R; Aston, Linda S; Song, Wenlu; Eitzer, Brian; Majumdar, Sanghamitra; Lapainis, Theodore; Mai, Huy; Tran, Kevin; El-Demerdash, Aref; Vega, Victor; Cai, Yanxuan; Wong, Jon W; Krynitsky, Alexandra J; Begley, Timothy H

2017-08-23

A collaborative study was conducted to evaluate stable isotope dilution assay (SIDA) and LC-MS/MS for the simultaneous determination of aflatoxins B 1 , B 2 , G 1 , and G 2 ; deoxynivalenol; fumonisins B 1 , B 2 , and B 3 ; ochratoxin A; HT-2 toxin; T-2 toxin; and zearalenone in foods. Samples were fortified with 12 13 C uniformly labeled mycotoxins ( 13 C-IS) corresponding to the native mycotoxins and extracted with acetonitrile/water (50:50 v/v), followed by centrifugation, filtration, and LC-MS/MS analysis. In addition to certified reference materials, the six participating laboratories analyzed corn, peanut butter, and wheat flour fortified with the 12 mycotoxins at concentrations ranging from 1.0 to 1000 ng/g. Using their available LC-MS/MS platform, each laboratory developed in-house instrumental conditions for analysis. The majority of recoveries ranged from 80 to 120% with relative standard derivations (RSDs) <20%. Greater than 90% of the average recoveries of the participating laboratories were in the range of 90-110%, with repeatability RSD r (within laboratory) < 10% and reproducibility RSD R (among laboratory) < 15%. All Z scores of the results of certified reference materials were between -2 and 2. Using 13 C-IS eliminated the need for matrix-matched calibration standards for quantitation, simplified sample preparation, and achieved simultaneous identification and quantitation of multiple mycotoxins in a simple LC-MS/MS procedure.

T2-mapping of the sacroiliac joints at 1.5 Tesla: a feasibility and reproducibility study.

PubMed

Albano, Domenico; Chianca, Vito; Cuocolo, Renato; Bignone, Rodolfo; Ciccia, Francesco; Sconfienza, Luca Maria; Midiri, Massimo; Brunetti, Arturo; Lagalla, Roberto; Galia, Massimo

2018-04-20

To evaluate the reproducibility of T2 relaxation time measurements of the sacroiliac joints at 1.5 T. Healthy volunteers underwent an oblique axial multislice multiecho spin-echo sequence of the sacroiliac joints at 1.5 T. Regions of interest were manually drawn using a dedicated software by two musculoskeletal radiologists to include the cartilaginous part of the sacroiliac joints. A senior radiologist performed the measurement twice, while a resident measured once. Intra- and inter-observer reproducibility was tested using the Bland-Altman method. Association between sex and T2 relaxation times was tested using the Mann-Whitney U test. Correlation between T2 relaxation times and body mass index (BMI) was tested using the Spearman's rho. Eighty sacroiliac joints of 40 subjects (mean age: 28 ± 4.8 years, range: 20-43; mean BMI: 23.3 ± 3.1, range: 18.9-30) were imaged. The mean T2 values obtained by the senior radiologist in the first series of measurements were 42 ± 4.4 ms, whereas in the second series were 40.7 ± 4.5 ms. The mean T2 values obtained by the radiology resident were 41.1 ± 4.2 ms. Intra-observer reproducibility was 88% (coefficient of repeatability = 3.8; bias = 1.28; p < .001), while inter-observer reproducibility was 86% (4.7; -.88; p < .001). There was significant association between sex and T2 relaxation times (p = .024) and significant inverse correlation between T2 relaxation times and BMI (r = -.340, p = .002). The assessment of T2 relaxation time measurements of sacroiliac joints seems to be highly reproducible at 1.5 T. Further studies could investigate the potential clinical application of this tool in the sacroiliac joints.

Pharmacokinetics of sarizotan after oral administration of single and repeat doses in healthy subjects.

PubMed

Krösser, S; Tillner, J; Fluck, M; Ungethüm, W; Wolna, P; Kovar, A

2007-05-01

Sarizotan is a 5-HTIA receptor agonist with high affinity for D3 and D4 receptors. Here we report the pharmacokinetic and tolerability results from four Phase 1 studies. Two single-dose (5 -25 mg, n = 25, 0.5 - 5 mg, n = 16) and two multiple-dose (10 and 20 mg b.i.d., n = 30, 5 mg b.i.d., n = 12) studies with orally administered sarizotan HCl were carried out in healthy subjects. Plasma sarizotan HCl concentrations were measured using a validated HPLC method and fluorescence or MS/MS detection. Pharmacokinetic parameters were obtained using standard non-compartmental methods. Sarizotan was rapidly absorbed, group-median times to reach maximum concentration (tmax) ranged from 0.5 -2.25 h after single doses and during steady state. Maximum plasma concentration (Cmax) and tmax were slightly dependent on formulation and food intake, whereas area under the curve (AUC) was unaffected by these factors. AUC and Cmax increased dose-proportionally over the tested dose range. Independently of dose and time, sarizotan HCl plasma concentrations declined polyexponentially with a terminal elimination half-life (t1/2) of 5 - 7 h. Accumulation factors corresponded to t1/2 values, and steady state was reached within 24 h. Plasma metabolite concentrations were considerably lower than those of the parent drug. The ratio metabolite AUC : parent drug AUC was time- and dose-independent for all three metabolites suggesting that the metabolism of sarizotan is non-saturable in the tested dose range. The pharmacokinetics of sarizotan were dose-proportional and time-independent for the dose range 0.5 -25 mg). The drug was well-tolerated by healthy subjects up to a single dose of 20 mg.

Robot-supported upper limb training in a virtual learning environment : a pilot randomized controlled trial in persons with MS.

PubMed

Feys, Peter; Coninx, Karin; Kerkhofs, Lore; De Weyer, Tom; Truyens, Veronik; Maris, Anneleen; Lamers, Ilse

2015-07-23

Despite the functional impact of upper limb dysfunction in multiple sclerosis (MS), effects of intensive exercise programs and specifically robot-supported training have been rarely investigated in persons with advanced MS. To investigate the effects of additional robot-supported upper limb training in persons with MS compared to conventional treatment only. Seventeen persons with MS (pwMS) (median Expanded Disability Status Scale of 8, range 3.5-8.5) were included in a pilot RCT comparing the effects of additional robot-supported training to conventional treatment only. Additional training consisted of 3 weekly sessions of 30 min interacting with the HapticMaster robot within an individualised virtual learning environment (I-TRAVLE). Clinical measures at body function (Hand grip strength, Motricity Index, Fugl-Meyer) and activity (Action Research Arm test, Motor Activity Log) level were administered before and after an intervention period of 8 weeks. The intervention group were also evaluated on robot-mediated movement tasks in three dimensions, providing active range of motion, movement duration and speed and hand-path ratio as indication of movement efficiency in the spatial domain. Non-parametric statistics were applied. PwMS commented favourably on the robot-supported virtual learning environment and reported functional training effects in daily life. Movement tasks in three dimensions, measured with the robot, were performed in less time and for the transporting and reaching movement tasks more efficiently. There were however no significant changes for any clinical measure in neither intervention nor control group although observational analyses of the included cases indicated large improvements on the Fugl-Meyer in persons with more marked upper limb dysfunction. Robot-supported training lead to more efficient movement execution which was however, on group level, not reflected by significant changes on standard clinical tests. Persons with more marked upper limb dysfunction may benefit most from additional robot-supported training, but larger studies are needed. This trial is registered within the registry Clinical Trials GOV ( NCT02257606 ).

Simultaneous quantification of cholesterol sulfate, androgen sulfates, and progestagen sulfates in human serum by LC-MS/MS[S

PubMed Central

Sánchez-Guijo, Alberto; Oji, Vinzenz; Hartmann, Michaela F.; Traupe, Heiko; Wudy, Stefan A.

2015-01-01

Steroids are primarily present in human fluids in their sulfated forms. Profiling of these compounds is important from both diagnostic and physiological points of view. Here, we present a novel method for the quantification of 11 intact steroid sulfates in human serum by LC-MS/MS. The compounds analyzed in our method, some of which are quantified for the first time in blood, include cholesterol sulfate, pregnenolone sulfate, 17-hydroxy-pregnenolone sulfate, 16-α-hydroxy-dehydroepiandrosterone sulfate, dehydroepiandrosterone sulfate, androstenediol sulfate, androsterone sulfate, epiandrosterone sulfate, testosterone sulfate, epitestosterone sulfate, and dihydrotestosterone sulfate. The assay was conceived to quantify sulfated steroids in a broad range of concentrations, requiring only 300 μl of serum. The method has been validated and its performance was studied at three quality controls, selected for each compound according to its physiological concentration. The assay showed good linearity (R2 > 0.99) and recovery for all the compounds, with limits of quantification ranging between 1 and 80 ng/ml. Averaged intra-day and between-day precisions (coefficient of variation) and accuracies (relative errors) were below 10%. The method has been successfully applied to study the sulfated steroidome in diseases such as steroid sulfatase deficiency, proving its diagnostic value. This is, to our best knowledge, the most comprehensive method available for the quantification of sulfated steroids in human blood. PMID:26239050

Size exclusion chromatography with online ICP-MS enables molecular weight fractionation of dissolved phosphorus species in water samples.

PubMed

Venkatesan, Arjun K; Gan, Wenhui; Ashani, Harsh; Herckes, Pierre; Westerhoff, Paul

2018-04-15

Phosphorus (P) is an important and often limiting element in terrestrial and aquatic ecosystem. A lack of understanding of its distribution and structures in the environment limits the design of effective P mitigation and recovery approaches. Here we developed a robust method employing size exclusion chromatography (SEC) coupled to an ICP-MS to determine the molecular weight (MW) distribution of P in environmental samples. The most abundant fraction of P varied widely in different environmental samples: (i) orthophosphate was the dominant fraction (93-100%) in one lake, two aerosols and DOC isolate samples, (ii) species of 400-600 Da range were abundant (74-100%) in two surface waters, and (iii) species of 150-350 Da range were abundant in wastewater effluents. SEC-DOC of the aqueous samples using a similar SEC column showed overlapping peaks for the 400-600 Da species in two surface waters, and for >20 kDa species in the effluents, suggesting that these fractions are likely associated with organic matter. The MW resolution and performance of SEC-ICP-MS agreed well with the time integrated results obtained using conventional ultrafiltration method. Results show that SEC in combination with ICP-MS and DOC has the potential to be a powerful and easy-to-use method in identifying unknown fractions of P in the environment. Copyright © 2018 Elsevier Ltd. All rights reserved.

Ambient Mass Spectrometry in Cancer Research.

PubMed

Takats, Z; Strittmatter, N; McKenzie, J S

2017-01-01

Ambient ionization mass spectrometry was developed as a sample preparation-free alternative to traditional MS-based workflows. Desorption electrospray ionization (DESI)-MS methods were demonstrated to allow the direct analysis of a broad range of samples including unaltered biological tissue specimens. In contrast to this advantageous feature, nowadays DESI-MS is almost exclusively used for sample preparation intensive mass spectrometric imaging (MSI) in the area of cancer research. As an alternative to MALDI, DESI-MSI offers matrix deposition-free experiment with improved signal in the lower (<500m/z) range. DESI-MSI enables the spatial mapping of tumor metabolism and has been broadly demonstrated to offer an alternative to frozen section histology for intraoperative tissue identification and surgical margin assessment. Rapid evaporative ionization mass spectrometry (REIMS) was developed exclusively for the latter purpose by the direct combination of electrosurgical devices and mass spectrometry. In case of the REIMS technology, aerosol particles produced by electrosurgical dissection are subjected to MS analysis, providing spectral information on the structural lipid composition of tissues. REIMS technology was demonstrated to give real-time information on the histological nature of tissues being dissected, deeming it an ideal tool for intraoperative tissue identification including surgical margin control. More recently, the method has also been used for the rapid lipidomic phenotyping of cancer cell lines as it was demonstrated in case of the NCI-60 cell line collection. © 2017 Elsevier Inc. All rights reserved.

Mass spectrometry of the photolysis of sulfonylurea herbicides in Prairie waters.

PubMed

Headley, John V; Du, Jing-Long; Peru, Kerry M; McMartin, Dena W

2010-01-01

This review of mass spectrometry of sulfonylurea herbicides includes a focus on studies relevant to Canadian Prairie waters. Emphasis is given to data gaps in the literature for the rates of photolysis of selected sulfonylurea herbicides in different water matrices. Specifically, results are evaluated for positive ion electrospray tandem mass spectrometry with liquid chromatography separation for the study of the photolysis of chlorsulfuron, tribenuron-methyl, thifensulfuron-methyl, metsulfuron-methyl, and ethametsulfuron-methyl. LC-MS/MS is shown to be the method of choice for the quantification of sulfonylurea herbicides with instrumental detection limits ranging from 1.3 to 7.2 pg (on-column). Tandem mass spectrometry coupled with the use of authentic standards likewise has proven to be well suited for the identification of transformation products. To date, however, the power of time-of-flight MS and ultrahigh resolution MS has not been exploited fully for the identification of unknown photolysis products. Dissipation of the herbicides under natural sunlight fit pseudo-first-order kinetics with half-life values ranging from 4.4 to 99 days. For simulated sunlight, radiation wavelengths shorter than 400 nm are required to induce significant photolytic reactions. The correlation between field dissipation studies and laboratory photolysis experiments suggests that photolysis is a major pathway for the dissipation of some sulfonylurea herbicides in natural Prairie waters. 2009 Wiley Periodicals, Inc.

Determination and pharmacokinetic study of pirfenidone in rat plasma by UPLC-MS/MS.

PubMed

Sun, Wei; Jiang, Zhe-li; Zhou, Lei; Chen, Rui-min; Wang, Zhe; Li, Wan-shu; Jiang, Shuo-min; Hu, Guo-xin; Chen, Rui-jie

2015-02-15

A rapid, sensitive and selective ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) was developed and validated for the determination and pharmacokinetic investigation of pirfenidone in rat plasma. Sample preparation was accomplished through a simple one-step deproteinization procedure with 0.2 mL of acetonitrile to a 0.1 mL plasma sample. Plasma samples were separated by UPLC on an Acquity UPLC BEH C18 column using a mobile phase consisting of acetonitrile-0.1% formic acid in water with gradient elution. The total run time was 3.0 min and the elution of pirfenidone was at 1.39 min. The detection was performed on a triple quadrupole tandem mass spectrometer in the multiple reaction-monitoring (MRM) mode using the respective transitions m/z 186.2→92.1 for pirfenidone and m/z 237.1→194.2 for carbamazepine (IS), respectively. The calibration curve was linear over the range of 5-2000 ng/mL with a lower limit of quantitation (LLOQ) of 5 ng/mL. Mean recovery of pirfenidone in plasma was in the range of 80.4-84.3%. Intra-day and inter-day precision were both <12.1%. This method was successfully applied in pharmacokinetic study after oral administration of 10.0mg/kg pirfenidone in rats. Copyright © 2015 Elsevier B.V. All rights reserved.

Simultaneous determination of triamcinolone hexacetonide and triamcinolone acetonide in rabbit plasma using a highly sensitive and selective UPLC-MS/MS method.

PubMed

Sun, Wei; Ho, Stacy; Fang, Xiaojun Rick; O'Shea, Thomas; Liu, Hanlan

2018-05-10

An ultra-high pressure liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was successfully developed and qualified for the simultaneous determination of triamcinolone hexacetonide (TAH) and triamcinolone acetonide (TAA, the active metabolite of TAH) in rabbit plasma. To prevent the hydrolysis of TAH to TAA ex vivo during sample collection and processing, we evaluated the effectiveness of several esterase inhibitors to stabilize TAH in plasma. Phenylmethanesulfonyl fluoride (PMSF) at 2.0 mM was chosen to stabilize TAH in rabbit plasma. The developed method is highly sensitive with a lower limit of quantitation of 10.0 pg/mL for both TAA and TAH using a 300 μL plasma aliquot. The method demonstrated good linearity, accuracy, precision, sensitivity, selectivity, recovery, matrix effects, dilution integrity, carryover, and stability. Linearity was obtained over the range of 10-2500 pg/mL. Both intra- and inter-run coefficients of variation were less than 9.1% and accuracies across the assay range were all within 100 ± 8.4%. The run time is under 5 minutes. The method was successfully implemented to support a rabbit pharmacokinetic study of TAH and TAA following a single intra-articular administration of TAH (Aristospan ® ). Copyright © 2018 Elsevier B.V. All rights reserved.

Dipole source localization of event-related brain activity indicative of an early visual selective attention deficit in ADHD children.

PubMed

Jonkman, L M; Kenemans, J L; Kemner, C; Verbaten, M N; van Engeland, H

2004-07-01

This study was aimed at investigating whether attention-deficit hyperactivity disorder (ADHD) children suffer from specific early selective attention deficits in the visual modality with the aid of event-related brain potentials (ERPs). Furthermore, brain source localization was applied to identify brain areas underlying possible deficits in selective visual processing in ADHD children. A two-channel visual color selection task was administered to 18 ADHD and 18 control subjects in the age range of 7-13 years and ERP activity was derived from 30 electrodes. ADHD children exhibited lower perceptual sensitivity scores resulting in poorer target selection. The ERP data suggested an early selective-attention deficit as manifested in smaller frontal positive activity (frontal selection positivity; FSP) in ADHD children around 200 ms whereas later occipital and fronto-central negative activity (OSN and N2b; 200-400 ms latency) appeared to be unaffected. Source localization explained the FSP by posterior-medial equivalent dipoles in control subjects, which may reflect the contribution of numerous surrounding areas. ADHD children have problems with selective visual processing that might be caused by a specific early filtering deficit (absent FSP) occurring around 200 ms. The neural sources underlying these problems have to be further identified. Source localization also suggested abnormalities in the 200-400 ms time range, pertaining to the distribution of attention-modulated activity in lateral frontal areas.

Newborn screening by matrix-assisted laser desorption/ionization mass spectrometry based on parylene-matrix chip.

PubMed

Kim, Jo-Il; Noh, Joo-Yoon; Kim, Mira; Park, Jong-Min; Song, Hyun-Woo; Kang, Min-Jung; Pyun, Jae-Chul

2017-08-01

Newborn screening for diagnosis of phenylketonuria, homocystinuria, and maple syrup urine disease have been conducted by analyzing the concentration of target amino acids using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-ToF MS) based on parylene-matrix chip. Parylene-matrix chip was applied to MALDI-ToF MS analysis reducing the matrix peaks significantly at low mass-to-charge ratio range (m/z < 500). Reproducibility of inter-spot and intra-spot analyses of amino acids was less than 10%. Methanol extraction was adopted for simple and rapid sample preparation of serum before mass spectrometric analysis showing 13.3 to 45% of extraction efficiency. Calibration curves for diagnosis of neonatal metabolic disorders were obtained by analyzing methanol-extracted serum spiked with target amino acids using MALDI-ToF MS. They showed good linearity (R 2  > 0.98) and the LODs were ranging from 9.0 to 22.9 μg/mL. Effect of proteins in serum was estimated by comparing MALDI-ToF mass spectra of amino acids-spiked serum before and after the methanol extraction. Interference of other amino acids on analysis of target analyte was determined to be insignificant. From these results, MALDI-ToF MS based on parylene-matrix chip could be applicable to medical diagnosis of neonatal metabolic disorders. Copyright © 2017 Elsevier Inc. All rights reserved.

Identification and Quantification of N-Acyl Homoserine Lactones Involved in Bacterial Communication by Small-Scale Synthesis of Internal Standards and Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry.

PubMed

Leipert, Jan; Treitz, Christian; Leippe, Matthias; Tholey, Andreas

2017-12-01

N-acyl homoserine lactones (AHL) are small signal molecules involved in the quorum sensing of many gram-negative bacteria, and play an important role in biofilm formation and pathogenesis. Present analytical methods for identification and quantification of AHL require time-consuming sample preparation steps and are hampered by the lack of appropriate standards. By aiming at a fast and straightforward method for AHL analytics, we investigated the applicability of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Suitable MALDI matrices, including crystalline and ionic liquid matrices, were tested and the fragmentation of different AHL in collision-induced dissociation MS/MS was studied, providing information about characteristic marker fragments ions. Employing small-scale synthesis protocols, we established a versatile and cost-efficient procedure for fast generation of isotope-labeled AHL standards, which can be used without extensive purification and yielded accurate standard curves. Quantitative analysis was possible in the low pico-molar range, with lower limits of quantification reaching from 1 to 5 pmol for different AHL. The developed methodology was successfully applied in a quantitative MALDI MS analysis of low-volume culture supernatants of Pseudomonas aeruginosa. Graphical abstract ᅟ.

Identification and Quantification of N-Acyl Homoserine Lactones Involved in Bacterial Communication by Small-Scale Synthesis of Internal Standards and Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry

NASA Astrophysics Data System (ADS)

Leipert, Jan; Treitz, Christian; Leippe, Matthias; Tholey, Andreas

2017-12-01

N-acyl homoserine lactones (AHL) are small signal molecules involved in the quorum sensing of many gram-negative bacteria, and play an important role in biofilm formation and pathogenesis. Present analytical methods for identification and quantification of AHL require time-consuming sample preparation steps and are hampered by the lack of appropriate standards. By aiming at a fast and straightforward method for AHL analytics, we investigated the applicability of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Suitable MALDI matrices, including crystalline and ionic liquid matrices, were tested and the fragmentation of different AHL in collision-induced dissociation MS/MS was studied, providing information about characteristic marker fragments ions. Employing small-scale synthesis protocols, we established a versatile and cost-efficient procedure for fast generation of isotope-labeled AHL standards, which can be used without extensive purification and yielded accurate standard curves. Quantitative analysis was possible in the low pico-molar range, with lower limits of quantification reaching from 1 to 5 pmol for different AHL. The developed methodology was successfully applied in a quantitative MALDI MS analysis of low-volume culture supernatants of Pseudomonas aeruginosa. [Figure not available: see fulltext.

Bioanalytical Method for Carbocisteine in Human Plasma by Using LC-MS/MS: A Pharmacokinetic Application.

PubMed

Dhanure, Shivanand; Savalia, Atulkumar; More, Pravinkumar; Shirode, Prashant; Kapse, Kailas; Shah, Virag

2014-01-01

A simple, sensitive, and selective LC-MS/MS method was developed and validated for the quantification of carbocisteine in human plasma. Rosiglitazone was used as the internal standard and heparin was used as the anticoagulant. The chromatographic separation was performed by using the Waters Symmetry Shield RP 8, 150 × 3.9 mm, 5 μ column at 40°C with a mobile phase consisting of a mixture of methanol and 0.5% formic acid solution in a 40:60 proportion. The flow rate was 500 μl/min along with a 5 μl injection volume. Protein precipitation was used as the extraction method. Mass spectrometric data were detected in positive ion mode. The MRM mode of the ions for carbocisteine was 180.0 > 89.0 and for rosiglitazone it was 238.1 > 135.1. The method was validated in the concentration curve range of 50.000 ng/mL to 6000.000 ng/mL. The retention times of carbocisteine and the internal standard rosiglitazone were approximately 2.20 and 3.01 min, respectively. The overall run time was 4.50 min. This method was found suitable to analyze human plasma samples for the application in pharmacokinetic and BA/BE studies.

The analysis of oral air using selected ion flow tube mass spectrometry in persons with and without a history of oral malodour.

PubMed

Ross, B M; Dadgostar, N; Bloom, M; McKeown, L

2009-05-01

Oral malodour is a common disorder predominantly caused by bacterial metabolism of food stuffs in the mouth. It is routinely diagnosed and monitored by either the subjective rating or the measurement of oral volatile sulphur compound (VSC) levels. Non-sulphur compounds are also believed to contribute significantly to the condition although there is currently no direct means to assess their levels. In this study, we utilized selective flow tube mass spectrometry (SIFT-MS) to measure, in real time, a range of sulphur and non-sulphur containing compounds in oral air to determine whether the technique can be used to objectively monitor oral malodour. Oral malodour was assessed using organoleptic scores in subjects with and without a history of oral malodour (n = 18) by a trained rater, while the chemical composition of oral air was analysed by both VSC sensor and SIFT-MS. Total VSC levels were significantly correlated with levels of hydrogen sulphide and methylmercaptan measured by SIFT-MS, but not with organoleptic scores. In subjects with elevated organoleptic score, only levels of methylmercaptan were significantly elevated. In three subjects with elevated tongue organoleptic scores but normal total VSC levels, SIFT-MS suggested that one subject possessed high levels of oral acetone while another had high oral levels of acetic acid. Our data suggest that SIFT-MS can be used to assess a wide range of compounds in oral air in addition to VSC to provide a clearer picture of the chemical nature of malodour. This may assist in the diagnosis and monitoring of the condition.

A sensitive and rapid ultra HPLC-MS/MS method for the simultaneous detection of clopidogrel and its derivatized active thiol metabolite in human plasma.

PubMed

Peer, Cody J; Spencer, Shawn D; VanDenBerg, Dustin A H; Pacanowski, Michael A; Horenstein, Richard B; Figg, William D

2012-01-01

A sensitive, selective, and rapid ultra-high performance liquid chromatography-tandem mass spectrometry (uHPLC-MS/MS) was developed for the simultaneous quantification of clopidogrel (Plavix(®)) and its derivatized active metabolite (CAMD) in human plasma. Derivatization of the active metabolite in blood with 2-bromo-3'-methoxy acetophenone (MPB) immediately after collection ensured metabolite stability during sample handling and storage. Following addition of ticlopidine as an internal standard and simple protein precipitation, the analytes were separated on a Waters Acquity UPLC™ sub-2 μm-C(18) column via gradient elution before detection on a triple-quadrupole MS with multiple-reaction-monitoring via electrospray ionization. The method was validated across the clinically relevant concentration range of 0.01-50 ng/mL for parent clopidogrel and 0.1-150 ng/mL (r(2)=0.99) for CAMD, with a fast run time of 1.5 min to support pharmacokinetic studies using 75, 150, or 300 mg oral doses of clopidogrel. The analytical method measured concentrations of clopidogrel and CAMD with accuracy (%DEV) <±12% and precision (%CV) of <±6%. The method was successfully applied to measure the plasma concentrations of clopidogrel and CAMD in three subjects administered single oral doses of 75, 150, and 300 mg clopidogrel. It was further demonstrated that the derivatizing agent (MPB) does not affect clopidogrel levels, thus from one aliquot of blood drawn clinically, this method can simultaneously quantify both clopidogrel and CAMD with sensitivity in the picogram per mL range. Published by Elsevier B.V.

A Sensitive and Rapid Ultra HPLC-MS/MS Method for the Simultaneous Detection of Clopidogrel and its Derivatized Active Thiol Metabolite in Human Plasma

PubMed Central

Peer, Cody J.; Spencer, Shawn D.; VanDenBerg, Dustin A. H.; Pacanowski, Michael A.; Horenstein, Richard B.; Figg, William D.

2011-01-01

A sensitive, selective, and rapid ultra-high performance liquid chromatography-tandem mass spectrometry (uHPLC-MS/MS) was developed for the simultaneous quantification of clopidogrel (Plavix®) and its derivatized active metabolite (CAMD) in human plasma. Derivatization of the active metabolite in blood with 2-bromo-3’-methoxy acetophenone (MPB) immediately after collection ensured metabolite stability during sample handling and storage. Following addition of ticlopidine as an internal standard and simple protein precipitation, the analytes were separated on a Waters Acquity UPLC™ sub-2µm-C18 column via gradient elution before detection on a triple-quadrupole MS with multiple-reaction-monitoring via electrospray ionization. The method was validated across the clinically-relevant concentration range of 0.01–50 ng/mL for parent clopidogrel and 0.1–150 ng/mL (r2= 0.99) for CAMD, with a fast run time of 1.5 min to support pharmacokinetic studies using 75, 150, or 300 mg oral doses of clopidogrel. The analytical method measured concentrations of clopidogrel and CAMD with accuracy (%DEV) < ±12% and precision (%CV) of < ±6%. The method was successfully applied to measure the plasma concentrations of clopidogrel and CAMD in three subjects administered single oral doses of 75, 150, and 300 mg clopidogrel. It was further demonstrated that the derivatizing agent (MPB) does not affect clopidogrel levels, thus from one aliquot of blood drawn clinically, this method can simultaneously quantify both clopidogrel and CAMD with sensitivity in the picogram per mL range. PMID:22169056

Wide-scope screening of pesticides in fruits and vegetables using information-dependent acquisition employing UHPLC-QTOF-MS and automated MS/MS library searching.

PubMed

Wang, Zhibin; Cao, Yanzhong; Ge, Na; Liu, Xiaomao; Chang, Qiaoying; Fan, Chunlin; Pang, Guo-Fang

2016-11-01

This paper presents an application of ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-QTOF-MS) for simultaneous screening and identification of 427 pesticides in fresh fruit and vegetable samples. Both full MS scan mode for quantification, and an artificial-intelligence-based product ion scan mode information-dependent acquisition (IDA) providing automatic MS to MS/MS switching of product ion spectra for identification, were conducted by one injection. A home-in collision-induced-dissociation all product ions accurate mass spectra library containing more than 1700 spectra was developed prior to actual application. Both qualitative and quantitative validations of the method were carried out. The result showed that 97.4 % of the pesticides had the screening detection limit (SDL) less than 50 μg kg -1 and more than 86.7 % could be confirmed by accurate MS/MS spectra embodied in the home-made library. Meanwhile, calibration curves covering two orders of magnitude were performed, and they were linear over the concentration range studied for the selected matrices (from 5 to 500 μg kg -1 for most of the pesticides). Recoveries between 80 and 110 % in four matrices (apple, orange, tomato, and spinach) at two spiked levels, 10 and 100 μg kg -1 , was 88.7 or 86.8 %. Furthermore, the overall relative standard deviation (RSD, n = 12) for 94.3 % of the pesticides in 10 μg kg -1 and 98.1 % of the pesticides in 100 μg kg -1 spiked levels was less than 20 %. In order to validate the suitability for routine analysis, the method was applied to 448 fruit and vegetable samples purchased in different local markets. The results show 83.3 % of the analyzed samples have positive findings (higher than the limits of identification and quantification), and 412 commodity-pesticide combinations are identified in our scope. The approach proved to be a cost-effective, time-saving and powerful strategy for routine large-scope screening of pesticides.

Measurement of trace levels of antibiotics in river water using on-line enrichment and triple-quadrupole LC-MS/MS.

PubMed

Dinh, Quoc Tuc; Alliot, Fabrice; Moreau-Guigon, Elodie; Eurin, Joëlle; Chevreuil, Marc; Labadie, Pierre

2011-09-15

This study presents the development of an automated on-line solid phase extraction (SPE)-liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the determination of 23 antibiotics in environmental water samples. After optimisation of LC-MS/MS conditions, SPE parameters such as sorbent type, sample pH or sample volume were optimised. Antibiotic recoveries ranged from 64% to 98% and compared favourably with those achieved using off-line SPE. Limits of detection were in the range 0.5-13.7 ng L(-1). This on-line SPE-LC-MS/MS procedure was applied to the analysis of water samples taken in three rivers within the Seine River basin, near Paris (France). The obtained results revealed the occurrence of 12 antibiotics, including tylosin, erythromycin, tetracycline, amoxicillin, trimethoprim, sulfamethoxazole, oxolinic acid, flumequine, norfloxacin, ciprofloxacin, ofloxacin, and vancomycin (2-1435 ng L(-1)). Copyright © 2011 Elsevier B.V. All rights reserved.

Magnetic resonance imaging as a surrogate outcome for multiple sclerosis relapses

PubMed Central

Petkau, J; Reingold, SC; Held, U; Cutter, GR; Fleming, TR; Hughes, MD; Miller, DH; McFarland, HF; Wolinsky, JS

2009-01-01

Background Magnetic resonance imaging (MRI) of lesions in the brain may be the best current candidate for a surrogate biological marker of clinical outcomes in relapsing remitting multiple sclerosis (MS), based on its role as an objective indicator of disease pathology. No biological surrogate marker has yet been validated for MS clinical outcomes. Objective The objective of this study was to use a multi-phased study to determine if a valid surrogate relationship could be demonstrated between counts of contrast enhancing lesions (CELs) and occurrence of relapses in MS. Methods We examined correlations for the concurrent and predictive relationship between CELs over 6 months and MS relapses over the same 6 months and an additional 6 months (total: 12 months), using available data on untreated patients from a large clinical trial and natural history database. Results Concurrent and predictive correlations were inadequate to justify continuation of this study to the planned additional phases required to demonstrate a surrogate relationship between CELs and MS relapses. Conclusions Confidence intervals for correlations between CELs and MS relapses exclude the possibility that CELs can be a good surrogate for relapses over the time scales we investigated. Further exploration of surrogacy between MRI measures and MS clinical outcomes may require improved datasets, the development of MRI techniques that couple better to clinical disease, and the ability to test a wide range of imaging- and clinically-based hypotheses for surrogacy. PMID:18535021

Targeted Data Extraction of the MS/MS Spectra Generated by Data-independent Acquisition: A New Concept for Consistent and Accurate Proteome Analysis*

PubMed Central

Gillet, Ludovic C.; Navarro, Pedro; Tate, Stephen; Röst, Hannes; Selevsek, Nathalie; Reiter, Lukas; Bonner, Ron; Aebersold, Ruedi

2012-01-01

Most proteomic studies use liquid chromatography coupled to tandem mass spectrometry to identify and quantify the peptides generated by the proteolysis of a biological sample. However, with the current methods it remains challenging to rapidly, consistently, reproducibly, accurately, and sensitively detect and quantify large fractions of proteomes across multiple samples. Here we present a new strategy that systematically queries sample sets for the presence and quantity of essentially any protein of interest. It consists of using the information available in fragment ion spectral libraries to mine the complete fragment ion maps generated using a data-independent acquisition method. For this study, the data were acquired on a fast, high resolution quadrupole-quadrupole time-of-flight (TOF) instrument by repeatedly cycling through 32 consecutive 25-Da precursor isolation windows (swaths). This SWATH MS acquisition setup generates, in a single sample injection, time-resolved fragment ion spectra for all the analytes detectable within the 400–1200 m/z precursor range and the user-defined retention time window. We show that suitable combinations of fragment ions extracted from these data sets are sufficiently specific to confidently identify query peptides over a dynamic range of 4 orders of magnitude, even if the precursors of the queried peptides are not detectable in the survey scans. We also show that queried peptides are quantified with a consistency and accuracy comparable with that of selected reaction monitoring, the gold standard proteomic quantification method. Moreover, targeted data extraction enables ad libitum quantification refinement and dynamic extension of protein probing by iterative re-mining of the once-and-forever acquired data sets. This combination of unbiased, broad range precursor ion fragmentation and targeted data extraction alleviates most constraints of present proteomic methods and should be equally applicable to the comprehensive analysis of other classes of analytes, beyond proteomics. PMID:22261725

Long-Term Predictive and Feedback Encoding of Motor Signals in the Simple Spike Discharge of Purkinje Cells

PubMed Central

Popa, Laurentiu S.; Streng, Martha L.

2017-01-01

Abstract Most hypotheses of cerebellar function emphasize a role in real-time control of movements. However, the cerebellum’s use of current information to adjust future movements and its involvement in sequencing, working memory, and attention argues for predicting and maintaining information over extended time windows. The present study examines the time course of Purkinje cell discharge modulation in the monkey (Macaca mulatta) during manual, pseudo-random tracking. Analysis of the simple spike firing from 183 Purkinje cells during tracking reveals modulation up to 2 s before and after kinematics and position error. Modulation significance was assessed against trial shuffled firing, which decoupled simple spike activity from behavior and abolished long-range encoding while preserving data statistics. Position, velocity, and position errors have the most frequent and strongest long-range feedforward and feedback modulations, with less common, weaker long-term correlations for speed and radial error. Position, velocity, and position errors can be decoded from the population simple spike firing with considerable accuracy for even the longest predictive (-2000 to -1500 ms) and feedback (1500 to 2000 ms) epochs. Separate analysis of the simple spike firing in the initial hold period preceding tracking shows similar long-range feedforward encoding of the upcoming movement and in the final hold period feedback encoding of the just completed movement, respectively. Complex spike analysis reveals little long-term modulation with behavior. We conclude that Purkinje cell simple spike discharge includes short- and long-range representations of both upcoming and preceding behavior that could underlie cerebellar involvement in error correction, working memory, and sequencing. PMID:28413823

Four-choice sound localization abilities of two Florida manatees, Trichechus manatus latirostris.

PubMed

Colbert, Debborah E; Gaspard, Joseph C; Reep, Roger; Mann, David A; Bauer, Gordon B

2009-07-01

The absolute sound localization abilities of two Florida manatees (Trichechus manatus latirostris) were measured using a four-choice discrimination paradigm, with test locations positioned at 45 deg., 90 deg., 270 deg. and 315 deg. angles relative to subjects facing 0 deg. Three broadband signals were tested at four durations (200, 500, 1000, 3000 ms), including a stimulus that spanned a wide range of frequencies (0.2-20 kHz), one stimulus that was restricted to frequencies with wavelengths shorter than their interaural time distances (6-20 kHz) and one that was limited to those with wavelengths longer than their interaural time distances (0.2-2 kHz). Two 3000 ms tonal signals were tested, including a 4 kHz stimulus, which is the midpoint of the 2.5-5.9 kHz fundamental frequency range of manatee vocalizations and a 16 kHz stimulus, which is in the range of manatee best-hearing sensitivity. Percentage correct within the broadband conditions ranged from 79% to 93% for Subject 1 and from 51% to 93% for Subject 2. Both performed above chance with the tonal signals but had much lower accuracy than with broadband signals, with Subject 1 at 44% and 33% and Subject 2 at 49% and 32% at the 4 kHz and 16 kHz conditions, respectively. These results demonstrate that manatees are able to localize frequency bands with wavelengths that are both shorter and longer than their interaural time distances and suggest that they have the ability to localize both manatee vocalizations and recreational boat engine noises.

Optimization of Microwave-Assisted Extraction Conditions for Five Major Bioactive Compounds from Flos Sophorae Immaturus (Cultivars of Sophora japonica L.) Using Response Surface Methodology.

PubMed

Liu, Jin-Liang; Li, Long-Yun; He, Guang-Hua

2016-03-02

Microwave-assisted extraction was applied to extract rutin; quercetin; genistein; kaempferol; and isorhamnetin from Flos Sophorae Immaturus. Six independent variables; namely; solvent type; particle size; extraction frequency; liquid-to-solid ratio; microwave power; and extraction time were examined. Response surface methodology using a central composite design was employed to optimize experimental conditions (liquid-to-solid ratio; microwave power; and extraction time) based on the results of single factor tests to extract the five major components in Flos Sophorae Immaturus. Experimental data were fitted to a second-order polynomial equation using multiple regression analysis. Data were also analyzed using appropriate statistical methods. Optimal extraction conditions were as follows: extraction solvent; 100% methanol; particle size; 100 mesh; extraction frequency; 1; liquid-to-solid ratio; 50:1; microwave power; 287 W; and extraction time; 80 s. A rapid and sensitive ultra-high performance liquid chromatography method coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry (EIS-Q-TOF MS/MS) was developed and validated for the simultaneous determination of rutin; quercetin; genistein; kaempferol; and isorhamnetin in Flos Sophorae Immaturus. Chromatographic separation was accomplished on a Kinetex C18 column (100 mm × 2.1 mm; 2.6 μm) at 40 °C within 5 min. The mobile phase consisted of 0.1% aqueous formic acid and acetonitrile (71:29; v/v). Isocratic elution was carried out at a flow rate of 0.35 mL/min. The constituents of Flos Sophorae Immaturus were simultaneously identified by EIS-Q-TOF MS/MS in multiple reaction monitoring mode. During quantitative analysis; all of the calibration curves showed good linear relationships (R² > 0.999) within the tested ranges; and mean recoveries ranged from 96.0216% to 101.0601%. The precision determined through intra- and inter-day studies showed an RSD% of <2.833%. These results demonstrate that the developed method is accurate and effective and could be readily utilized for the comprehensive quality control of Flos Sophorae Immaturus.

Optimized efficient liver T1ρ mapping using limited spin lock times

NASA Astrophysics Data System (ADS)

Yuan, Jing; Zhao, Feng; Griffith, James F.; Chan, Queenie; Wang, Yi-Xiang J.

2012-03-01

T1ρ relaxation has recently been found to be sensitive to liver fibrosis and has potential to be used for early detection of liver fibrosis and grading. Liver T1ρ imaging and accurate mapping are challenging because of the long scan time, respiration motion and high specific absorption rate. Reduction and optimization of spin lock times (TSLs) are an efficient way to reduce scan time and radiofrequency energy deposition of T1ρ imaging, but maintain the near-optimal precision of T1ρ mapping. This work analyzes the precision in T1ρ estimation with limited, in particular two, spin lock times, and explores the feasibility of using two specific operator-selected TSLs for efficient and accurate liver T1ρ mapping. Two optimized TSLs were derived by theoretical analysis and numerical simulations first, and tested experimentally by in vivo rat liver T1ρ imaging at 3 T. The simulation showed that the TSLs of 1 and 50 ms gave optimal T1ρ estimation in a range of 10-100 ms. In the experiment, no significant statistical difference was found between the T1ρ maps generated using the optimized two-TSL combination and the maps generated using the six TSLs of [1, 10, 20, 30, 40, 50] ms according to one-way ANOVA analysis (p = 0.1364 for liver and p = 0.8708 for muscle).

High-performance multiple-reflection time-of-flight mass spectrometers for research with exotic nuclei and for analytical mass spectrometry

NASA Astrophysics Data System (ADS)

Plaß, Wolfgang R.; Dickel, Timo; Ayet San Andres, Samuel; Ebert, Jens; Greiner, Florian; Hornung, Christine; Jesch, Christian; Lang, Johannes; Lippert, Wayne; Majoros, Tamas; Short, Devin; Geissel, Hans; Haettner, Emma; Reiter, Moritz P.; Rink, Ann-Kathrin; Scheidenberger, Christoph; Yavor, Mikhail I.

2015-11-01

A class of multiple-reflection time-of-flight mass spectrometers (MR-TOF-MSs) has been developed for research with exotic nuclei at present and future accelerator facilities such as GSI and FAIR (Darmstadt), and TRIUMF (Vancouver). They can perform highly accurate mass measurements of exotic nuclei, serve as high-resolution, high-capacity mass separators and be employed as diagnostics devices to monitor the production, separation and manipulation of beams of exotic nuclei. In addition, a mobile high-resolution MR-TOF-MS has been developed for in situ applications in analytical mass spectrometry ranging from environmental research to medicine. Recently, the MR-TOF-MS for GSI and FAIR has been further developed. A novel RF quadrupole-based ion beam switchyard has been developed that allows merging and splitting of ion beams as well as transport of ions into different directions. It efficiently connects a test and reference ion source and an auxiliary detector to the system. Due to an increase in the kinetic energy of the ions in the time-of-flight analyzer of the MR-TOF-MS, a given mass resolving power is now achieved in less than half the time-of-flight. Conversely, depending on the time-of-flight, the mass resolving power has been increased by a factor of more than two.

[Quantitative determination of biogenic amine from Biomphalaria glabrata nervous system by UPLC MS/MS].

PubMed

Tao, Huang; Yun-Hai, Guo; He-Xiang, Liu; Yi, Zhang

2018-04-19

To establish a method for the quantitative determination of serotonin and dopamine in the nervous system of Biomphalaria glabrata by using ultra high performance liquid chromatography-tandem quadrupole mass spectrometry (UPLC MS/MS) . The B. glabrata nervous system was broken in the pure methanol solution after obtaining it by dissecting with microscope. Then, the supernatant containing the target substance after twice high speed centrifugation was got. The extraction was separated on an ACQUITY UPLC BEH Amide column with Waters TQ-XS series mass spectrometry detector, with ESI source and positive electrospray ionization mode when the machine testing. The detection limit of serotonin was 0.03 ng/ml and the limit of quantification was 0.1 ng/ml. The detection limit of dopamine was 0.05 ng/ml and the limit of quantification was 0.15 ng/ml. The recoveries of serotonin ranged from 90.68% to 94.72% over the range of 1 to 40 ng/ml. The recoveries of dopamine ranged from 91.68% to 96.12% over the range of 1.0 ng/ml to 40 ng/ml. The established UPLC MS/MS method is simple, stable and reproducible. It can be used for the quantitative analysis of serotonin and dopamine in the nervous system of B. glabrata snails.

Evaluation of MALDI-TOF-MS for the Identification of Yeast Isolates Causing Bloodstream Infection.

PubMed

Turhan, Ozge; Ozhak-Baysan, Betil; Zaragoza, Oscar; Er, Halil; Sarıtas, Zubeyde Eres; Ongut, Gozde; Ogunc, Dilara; Colak, Dilek; Cuenca-Estrella, Manuel

2017-04-01

Infections due to Candida species are major causes of morbidity and mortality in humans, causing a diverse spectrum of clinical disease ranging from superficial and mucosal infections to invasive disease. Several authors have demonstrated that mortality is closely linked to both timing of therapy and/or source control. The rapid identification of pathogenic species is helpful to start timely and effective antifungal therapy. The aim of this study was to assess the performance of the matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) system for the correct and rapid identification of yeast isolates causing bloodstream infection. Between January 2014 and January 2015, a total of 117 yeast like organisms isolated from blood culture samples of 117 episodes from 102 patients who had blood stream infections were included in the study. The isolates were identified by MALDI-TOF MS. The results were compared with those obtained by the standard mycological methods and/or sequence analysis. One hundred and seventeen yeast isolates including 115 Candida spp and two non-Candida yeasts were analysed. The Biotyper correctly identified 115 (98.3%) isolates to the genus level and 102 (87.2%) isolates to the species level using the manufacturer's recommended cutoff scores. The Bruker Biotyper is a rapid, easy, inexpensive, and highly reliable system for the identification of yeast isolates. Early identification with MALDI-TOF MS would save time for determination of antifungal susceptibility and proper treatment strategy. The expansion of the database of the library by addition of less common species will improve the performance of the system.

Who benefits most from THC:CBD spray? Learning from clinical experience.

PubMed

Koehler, Jürgen

2014-01-01

Patients with multiple sclerosis (MS) represent a diverse and heterogeneous population varying in terms of disease type, its severity and variable progression/time-course, and with regard to the wide range of presenting symptoms. Consequently, detailed experience with individual patients is important to provide examples of therapy to specific patient types. In this article, real-life data from clinical practice showing specific aspects relating to use of 9-delta-tetrahydocannabinol and cannabidiol (THC:CBD) oromucosal spray (Sativex®) in patients with moderate to severe spasticity resistant to usual therapy will be presented. Three common clinical scenarios will be considered: MS patients with resistance to usual spasticity therapies; patients with impairment in MS spasticity symptoms; MS patients with relevant impairment in quality of life/activities of daily living (QoL/ADL). These case reports highlight the diverse nature of the MS spasticity population and they show the possible usefulness of THC:CBD oromucosal spray in individual patients with moderate to severe spasticity resistant to existing therapies, within the frame of use approved after large clinical trial results. Perhaps the most important finding is the possibility of obtaining relevant improvements in QoL/ADL in some patients with resistant MS spasticity, allowing them to engage back in physical and social activities. © 2014 S. Karger AG, Basel.

Rapid quantitative analysis of 8-iso-prostaglandin-F(2alpha) using liquid chromatography-tandem mass spectrometry and comparison with an enzyme immunoassay method.

PubMed

Dahl, Jeffrey H; van Breemen, Richard B

2010-09-15

A rapid liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay was developed for the measurement of urinary 8-iso-prostaglandin F(2alpha) (8-iso-PGF(2alpha)), a biomarker of lipid peroxidation. Because urine contains numerous F(2) prostaglandin isomers, each with identical mass and similar mass spectrometric fragmentation patterns, chromatographic separation of 8-iso-PGF(2alpha) from its isomers is necessary for its quantitative analysis using MS/MS. We were able to achieve this separation using an isocratic LC method with a run time of less than 9min, which is at least threefold faster than previous methods, while maintaining sensitivity, accuracy, precision, and reliability. The limits of detection and quantitation were 53 and 178pg/ml urine, respectively. We compared our method with a commercially available affinity purification and enzyme immunoassay kit and found both assays to be in agreement. Despite the high sensitivity of the enzyme immunoassay method, it is more expensive and has a narrower dynamic range than LC-MS/MS. Our method was optimized for rapid measurement of 8-iso-PGF(2alpha) in urine, and it is ideally suited for clinical sample analysis. 2010 Elsevier Inc. All rights reserved.

Structure determination and sensory analysis of bitter-tasting 4-vinylcatechol oligomers and their identification in roasted coffee by means of LC-MS/MS.

PubMed

Frank, Oliver; Blumberg, Simone; Kunert, Christof; Zehentbauer, Gerhard; Hofmann, Thomas

2007-03-07

Aimed at elucidating intense bitter-tasting molecules in coffee, various bean ingredients were thermally treated in model experiments and evaluated for their potential to produce bitter compounds. As caffeic acid was found to generate intense bitterness reminiscent of the bitter taste of a strongly roasted espresso-type coffee, the reaction products formed were screened for bitter compounds by means of taste dilution analysis, and the most bitter tastants were isolated and purified. LC-MS/MS as well as 1-D/2-D NMR experiments enabled the identification of 10 bitter compounds with rather low recognition threshold concentrations ranging between 23 and 178 micromol/L. These bitter compounds are the previously unreported 1,3-bis(3',4'-dihydroxyphenyl) butane, trans-1,3-bis(3',4'-dihydroxyphenyl)-1-butene, and eight multiply hydroxylated phenylindanes, among which five derivatives are reported for the first time. In addition, the occurrence of each of these bitter compounds in a coffee brew was verified by means of LC-MS/MS (ESI-) operating in the multiple reaction monitoring (MRM) mode. The structures of these bitter compounds show strong evidence that they are generated by oligomerization of 4-vinylcatechol released from caffeic acid moieties upon roasting.

Targeted Proteomic Quantification on Quadrupole-Orbitrap Mass Spectrometer*

PubMed Central

Gallien, Sebastien; Duriez, Elodie; Crone, Catharina; Kellmann, Markus; Moehring, Thomas; Domon, Bruno

2012-01-01

There is an immediate need for improved methods to systematically and precisely quantify large sets of peptides in complex biological samples. To date protein quantification in biological samples has been routinely performed on triple quadrupole instruments operated in selected reaction monitoring mode (SRM), and two major challenges remain. Firstly, the number of peptides to be included in one survey experiment needs to be increased to routinely reach several hundreds, and secondly, the degree of selectivity should be improved so as to reliably discriminate the targeted analytes from background interferences. High resolution and accurate mass (HR/AM) analysis on the recently developed Q-Exactive mass spectrometer can potentially address these issues. This instrument presents a unique configuration: it is constituted of an orbitrap mass analyzer equipped with a quadrupole mass filter as the front-end for precursor ion mass selection. This configuration enables new quantitative methods based on HR/AM measurements, including targeted analysis in MS mode (single ion monitoring) and in MS/MS mode (parallel reaction monitoring). The ability of the quadrupole to select a restricted m/z range allows one to overcome the dynamic range limitations associated with trapping devices, and the MS/MS mode provides an additional stage of selectivity. When applied to targeted protein quantification in urine samples and benchmarked with the reference SRM technique, the quadrupole-orbitrap instrument exhibits similar or better performance in terms of selectivity, dynamic range, and sensitivity. This high performance is further enhanced by leveraging the multiplexing capability of the instrument to design novel acquisition methods and apply them to large targeted proteomic studies for the first time, as demonstrated on 770 tryptic yeast peptides analyzed in one 60-min experiment. The increased quality of quadrupole-orbitrap data has the potential to improve existing protein quantification methods in complex samples and address the pressing demand of systems biology or biomarker evaluation studies. PMID:22962056

Simultaneous quantification of iodine and high valent metals via ICP-MS under acidic conditions in complex matrices.

PubMed

Brix, Kristina; Hein, Christina; Sander, Jonas Michael; Kautenburger, Ralf

2017-05-15

The determination of iodine as a main fission product (especially the isotopes I-129 and I-131) of stored HLW in a disposal beside its distribution as a natural ingredient of many different products like milk, food and seawater is a matter of particular interest. The simultaneous ICP-MS determination of iodine as iodide together with other elements (especially higher valent metal ions) relevant for HLW is analytically very problematic. A reliable ICP-MS quantification of iodide must be performed at neutral or alkaline conditions in contrast to the analysis of metal ions which are determined in acidic pH ranges. Herein, we present a method to solve this problem by changing the iodine speciation resulting in an ICP-MS determination of iodide as iodate. The oxidation from iodide to iodate with sodium hypochlorite at room temperature is a fast and convenient method with flexible reaction time, from one hour up to three days, thus eliminating the disadvantages of quantifying iodine species via ICP-MS. In the analysed concentration range of iodine (0.1-100µgL -1 ) we obtain likely quantitative recovery rates for iodine between 91% and 102% as well as relatively low RSD values (0.3-4.0%). As an additional result, it is possible to measure different other element species in parallel together with the generated iodate, even high valent metals (europium and uranium beside caesium) at recovery rates in the same order of magnitude (93-104%). In addition, the oxidation process operates above pH 7 thus offering a wide pH range for sample preparation. Even analytes in complex matrices, like 5M saline (NaCl) solution or artificial cement pore water (ACW) can be quantified with this robust sample preparation method. Copyright © 2017 Elsevier B.V. All rights reserved.

Accurate LC peak boundary detection for ¹⁶O/¹⁸O labeled LC-MS data.

PubMed

Cui, Jian; Petritis, Konstantinos; Tegeler, Tony; Petritis, Brianne; Ma, Xuepo; Jin, Yufang; Gao, Shou-Jiang S J; Zhang, Jianqiu Michelle

2013-01-01

In liquid chromatography-mass spectrometry (LC-MS), parts of LC peaks are often corrupted by their co-eluting peptides, which results in increased quantification variance. In this paper, we propose to apply accurate LC peak boundary detection to remove the corrupted part of LC peaks. Accurate LC peak boundary detection is achieved by checking the consistency of intensity patterns within peptide elution time ranges. In addition, we remove peptides with erroneous mass assignment through model fitness check, which compares observed intensity patterns to theoretically constructed ones. The proposed algorithm can significantly improve the accuracy and precision of peptide ratio measurements.

Accurate LC Peak Boundary Detection for 16 O/ 18 O Labeled LC-MS Data

PubMed Central

Cui, Jian; Petritis, Konstantinos; Tegeler, Tony; Petritis, Brianne; Ma, Xuepo; Jin, Yufang; Gao, Shou-Jiang (SJ); Zhang, Jianqiu (Michelle)

2013-01-01

In liquid chromatography-mass spectrometry (LC-MS), parts of LC peaks are often corrupted by their co-eluting peptides, which results in increased quantification variance. In this paper, we propose to apply accurate LC peak boundary detection to remove the corrupted part of LC peaks. Accurate LC peak boundary detection is achieved by checking the consistency of intensity patterns within peptide elution time ranges. In addition, we remove peptides with erroneous mass assignment through model fitness check, which compares observed intensity patterns to theoretically constructed ones. The proposed algorithm can significantly improve the accuracy and precision of peptide ratio measurements. PMID:24115998

Pairwise alignment of chromatograms using an extended Fisher-Rao metric.

PubMed

Wallace, W E; Srivastava, A; Telu, K H; Simón-Manso, Y

2014-09-02

A conceptually new approach for aligning chromatograms is introduced and applied to examples of metabolite identification in human blood plasma by liquid chromatography-mass spectrometry (LC-MS). A square-root representation of the chromatogram's derivative coupled with an extended Fisher-Rao metric enables the computation of relative differences between chromatograms. Minimization of these differences using a common dynamic programming algorithm brings the chromatograms into alignment. Application to a complex sample, National Institute of Standards and Technology (NIST) Standard Reference Material 1950, Metabolites in Human Plasma, analyzed by two different LC-MS methods having significantly different ranges of elution time is described. Published by Elsevier B.V.

STS-35 MS Hoffman and PS Durrance on OV-102's middeck for 'Space Classroom'

NASA Technical Reports Server (NTRS)

1990-01-01

STS-35 Mission Specialist (MS) Jeffrey A. Hoffman (mustache) and Payload Specialist (PS) Samuel T. Durrance conduct 'Space Classroom Assignment: The Stars' on the middeck of Columbia, Orbiter Vehicle (OV) 102. These crewmembers are giving students a lesson on the electromagnetic spectrum. Displayed behind them on the orbiter galley is a chart showing the range of light visible by each telescope that is operating in OV-102's payload bay (PLB) during the Astronomy Laboratory 1 (ASTRO-1) mission. Live television allowed the space experts to give real-time observations and commentaries to the Earth-based academic audiences.

Multichannel Poisson denoising and deconvolution on the sphere: application to the Fermi Gamma-ray Space Telescope

NASA Astrophysics Data System (ADS)

Schmitt, J.; Starck, J. L.; Casandjian, J. M.; Fadili, J.; Grenier, I.

2012-10-01

A multiscale representation-based denoising method for spherical data contaminated with Poisson noise, the multiscale variance stabilizing transform on the sphere (MS-VSTS), has been previously proposed. This paper first extends this MS-VSTS to spherical two and one dimensions data (2D-1D), where the two first dimensions are longitude and latitude, and the third dimension is a meaningful physical index such as energy or time. We then introduce a novel multichannel deconvolution built upon the 2D-1D MS-VSTS, which allows us to get rid of both the noise and the blur introduced by the point spread function (PSF) in each energy (or time) band. The method is applied to simulated data from the Large Area Telescope (LAT), the main instrument of the Fermi Gamma-ray Space Telescope, which detects high energy gamma-rays in a very wide energy range (from 20 MeV to more than 300 GeV), and whose PSF is strongly energy-dependent (from about 3.5 at 100 MeV to less than 0.1 at 10 GeV).

Hazardous Gas Leak Analysis in the Space Shuttle

NASA Technical Reports Server (NTRS)

Barile, Ronald G.

1991-01-01

Helium tests of the main propulsion system in the Space Shuttle and on hydrogen leaks are examined. The hazardous gas detection system (HGDS) in the mobile launch pad uses mass spectrometers (MS) to monitor the shuttle environment for leaks. The mass spectrometers are fed by long tubes to sample gas from the payload bay, mid-body, aft engine compartment, and external tank. The purpose is to improve the HGDS, especially in its potential for locating cryogen leaks. Pre-existing leak data was analyzed for transient information to determine if the leak location could be pinpointed from test data. A rapid response leak detection experiment was designed, built, and tested. Large eddies and vortices were visually seen with Schlieren imaging, and they were detected in the time plots of the various instruments. The response time of the MS was found in the range of 0.05 to 0.1 sec. Pulsed concentration waves were clearly detected at 25 cycles per sec by spectral analysis of MS data. One conclusion is that the backup HGDS sampling frequency should be increased above the present rate of 1 sample per second.

Analysis of anabolic steroids in human hair using LC-MS/MS.

PubMed

Deshmukh, Nawed; Hussain, Iltaf; Barker, James; Petroczi, Andrea; Naughton, Declan P

2010-10-01

New highly sensitive, specific, reliable, reproducible and robust LC-MS/MS methods were developed to detect the anabolic steroids, nandrolone and stanozolol, in human hair for the first time. Hair samples from 180 participants (108 males, 72 females, 62% athletes) were screened using ELISA which revealed 16 athletes as positive for stanozolol and 3 for nandrolone. Positive samples were confirmed on LC-MS/MS in selective reaction monitoring (SRM) mode. The assays for stanozolol and nandrolone showed good linearity in the range 1-400pg/mg and 5-400pg/mg, respectively. The methods were validated for LLOD, interday precision, intraday precision, specificity, extraction recovery and accuracy. The assays were capable of detecting 0.5pg stanozolol and 3.0pg nandrolone per mg of hair, when approximately 20mg of hair were processed. Analysis using LC-MS/MS confirmed 11 athletes' positive for stanozolol (5.0pg/mg to 86.3pg/mg) and 1 for nandrolone (14.0pg/mg) thus avoiding false results from ELISA screening. The results obtained demonstrate the application of these hair analysis methods to detect both steroids at low concentrations, hence reducing the amount of hair required significantly. The new methods complement urinalysis or blood testing and facilitate improved doping testing regimes. Hair analysis benefits from non-invasiveness, negligible risk of infection and facile sample storage and collection, whilst reducing risks of tampering and cross-contamination. Owing to the wide detection window, this approach may also offer an alternative approach for out-of-competition testing.

Rapid and interference-free analysis of nine B-group vitamins in energy drinks using trilinear component modeling of liquid chromatography-mass spectrometry data.

PubMed

Hu, Yong; Wu, Hai-Long; Yin, Xiao-Li; Gu, Hui-Wen; Xiao, Rong; Xie, Li-Xia; Liu, Zhi; Fang, Huan; Wang, Li; Yu, Ru-Qin

2018-04-01

The aim of the present work was to develop a rapid and interference-free method based on liquid chromatography-mass spectrometry (LC-MS) for the simultaneous determination of nine B-group vitamins in various energy drinks. A smart and green strategy that modeled the three-way data array of LC-MS with second-order calibration methods based on alternating trilinear decomposition (ATLD) and alternating penalty trilinear decomposition (APTLD) algorithms was developed. By virtue of "mathematical separation" and "second-order advantage", the proposed strategy successfully solved the co-eluted peaks and unknown interferents in LC-MS analysis with the elution time less than 4.5min and simple sample preparation. Satisfactory quantitative results were obtained by the ATLD-LC-MS and APTLD-LC-MS methods for the spiked recovery assays, with the average spiked recoveries ranging from 87.2-113.9% to 92.0-111.7%, respectively. These results acquired from the proposed methods were confirmed by the LC-MS/MS method, which shows a quite good consistency with each other. All these results demonstrated that the developed chemometrics-assisted LC-MS strategy had advantages of being rapid, green, accurate and low-cost, and it could be an attractive alternative for the determination of multiple vitamins in complex food matrices, which required no laborious sample preparation, tedious condition optimization or more sophisticated instrumentations. Copyright © 2017 Elsevier B.V. All rights reserved.

Sheathless interface to match flow rate of capillary electrophoresis with electrospray mass spectrometry using regular-sized capillary.

PubMed

Yin, Yue; Li, Gongyu; Guan, Yafeng; Huang, Guangming

2016-08-01

The flow rate match has been a great challenge when coupling capillary electrophoresis (CE) with electrospray ionization mass spectrometry (ESI-MS). Conventional CE-ESI-MS interfaces used liquid sheath flow, narrowed capillary or additional pressure to meet this requirement; sacrifice of either capillary inner diameter (i.d.) or separation efficiency is often inevitable. Thus, a regular-sized capillary-based sheathless interface would be attractive for flow rate match in CE-MS. The regular-sized capillary-based CE-MS interface was achieved by coupling CE with induced electrospray ionization (iESI) which was stimulated by the fact that the iESI could both achieve flow rate down to 0.2 μL/min and retain ionization efficiency. The CE-iESI-MS interface was completed with an intact separation capillary, outside the outlet end of which a metal electrode was attached for the application of alternating current (ac) high voltage (HV). The feasibility of this CE-iESI-MS interface was demonstrated through the stable total ion chromatograms obtained by continuous CE infusion of tripropylamine with regular-sized capillaries. Tripropylamine and atenolol were separated and detected successfully in phosphate buffer solution (PBS) by CE-iESI-MS using a 50 or 75 μm i.d. capillary. Furthermore, this new interface showed a better signal-to-noise (S/N) of 3 to 7 times enhancement compared with another sheathless CE-ESI-MS interface that using one high voltage for both separation and electrospray when analyzing the mixture of tripropylamine and proline in NH4 OAc buffer. In addition, the reproducibility of this interface gave satisfactory results with relative standard deviation (RSD) in retention time in the range between 1% and 3%. The novel sheathless CE-MS interface introduced here could match conventional electroosmotic flow (EOF) with electrospray which could also preserve the separation efficiency and sensitivity of CE-MS. This newly developed CE-iESI-MS interface was also demonstrated to be effective for different buffers, PBS and NH4 OAc, without any additives such as methanol and acetic acid. Hence, we believe that this sheathless CE-MS interface could be operated with other nonvolatile and volatile buffers. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Millimeter Wave Alternate Route Study.

DTIC Science & Technology

1981-04-01

processing gains are based upon the assumption that the jammer equally distributes his available power over all the hopping frequencies. If this is true...Examples Assumptions 0 25 GHz hopping range (e.g., 20 GHz to 45 GHz) 0 10 ms settling time * 0.1 second dwell time - implies 11% increase in channel data...of the architectures presented previously. The assumption that each link has equal probability p of being disrupted (i.e., successfully jammed) seems

Quantification of sugars and sugar phosphates in Arabidopsis thaliana tissues using porous graphitic carbon liquid chromatography-electrospray ionization mass spectrometry.

PubMed

Antonio, Carla; Larson, Tony; Gilday, Alison; Graham, Ian; Bergström, Ed; Thomas-Oates, Jane

2007-11-23

This work reports the development and optimisation of a negative ion mode on-line LC-ESI-MS/MS method for the sensitive targeted analysis of the key glycolytic intermediates, sugars and sugar phosphates from plants, using a porous graphitic carbon (PGC) stationary phase and an MS compatible mobile phase. Using this newly developed method, separation and detection of a solution of standard compounds is achieved in less than 20min. Target metabolite compounds were identified in plant extracts from their characteristic retention times, and product ion spectra. This on-line PGC-ESI-MS/MS method shows good linearity over the concentration range 0-100microM, selectivity, short analysis time, and limits of detection of 0.1microM for disaccharides trehalose (Tre), sucrose (Suc), and maltose, and 1.5microM for hexose phosphates fructose-6-phosphate (Fru6P), glucose-1-phosphate (Glc1P), and glucose-6-phosphate (Glc6P), and phosphoenolpyruvate (PEP). This paper describes details of our method and its application to the simultaneous quantitative analysis of soluble sugars and sugar phosphates from Arabidopsis thaliana tissues. We have demonstrated the utility of our method for the analysis of biological samples by applying it to the simultaneous quantitation of changes in soluble sugars and sugar phosphates in A. thaliana Columbia-0 (Col-0) and its starchless phosphoglucomutase (pgm) mutant over a 12-h light/12-h dark growth cycle.

Bacillus Classification Based on Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry-Effects of Culture Conditions.

PubMed

Shu, Lin-Jie; Yang, Yu-Liang

2017-11-14

Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) is a reliable and rapid technique applied widely in the identification and classification of microbes. MALDI-TOF MS has been used to identify many endospore-forming Bacillus species; however, endospores affect the identification accuracy when using MALDI-TOF MS because they change the protein composition of samples. Since culture conditions directly influence endospore formation and Bacillus growth, in this study we clarified how culture conditions influence the classification of Bacillus species by using MALDI-TOF MS. We analyzed members of the Bacillus subtilis group and Bacillus cereus group using different incubation periods, temperatures and media. Incubation period was found to affect mass spectra due to endospores which were observed mixing with vegetative cells after 24 hours. Culture temperature also resulted in different mass spectra profiles depending on the temperature best suited growth and sporulation. Conversely, the four common media for Bacillus incubation, Luria-Bertani agar, nutrient agar, plate count agar and brain-heart infusion agar did not result in any significant differences in mass spectra profiles. Profiles in the range m/z 1000-3000 were found to provide additional data to the standard ribosomal peptide/protein region m/z 3000-15000 profiles to enable easier differentiation of some highly similar species and the identification of new strains under fresh culture conditions. In summary, control of culture conditions is vital for Bacillus identification and classification by MALDI-TOF MS.

The Exploration of Peptide Biomarkers in Malignant Pleural Effusion of Lung Cancer Using Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry

PubMed Central

Xu, Jing; Xu, Bin; Tang, Chuanhao; Li, Xiaoyan; Qin, Haifeng; Wang, Weixia; Wang, Hong; Wang, Zhongyuan; Li, Liangliang; Li, Zhihua; Gao, Hongjun

2017-01-01

Background. Diagnoses of malignant pleural effusion (MPE) are a crucial problem in clinics. In our study, we compared the peptide profiles of MPE and tuberculosis pleural effusion (TPE) to investigate the value of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) in diagnosis of MPE. Material and Methods. The 46 MPE and 32 TPE were randomly assigned to training set and validation set. Peptides were isolated by weak cation exchange magnetic beads and peaks in the m/z range of 800–10000 Da were analyzed. Comparing the peptide profile between 30 MPE and 22 TPE samples in training set by ClinProTools software, we screened the specific biomarkers and established a MALDI-TOF-MS classification of MPE. Finally, the other 16 MPE and 10 TPE were included to verify the model. We additionally determined carcinoembryonic antigen (CEA) in MPE and TPE samples using electrochemiluminescent immunoassay method. Results. Five peptide peaks (917.37 Da, 4469.39 Da, 1466.5 Da, 4585.21 Da, and 3216.87 Da) were selected to separate MPE and TPE by MALDI-TOF-MS. The sensitivity, specificity, and accuracy of the classification were 93.75%, 100%, and 96.15%, respectively, after blinded test. The sensitivity of CEA was significantly lower than MALDI-TOF-MS classification (P = 0.035). Conclusions. The results indicate MALDI-TOF-MS is a potential method for diagnosing MPE. PMID:28386154

The Exploration of Peptide Biomarkers in Malignant Pleural Effusion of Lung Cancer Using Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry.

PubMed

Xu, Jing; Xu, Bin; Tang, Chuanhao; Li, Xiaoyan; Qin, Haifeng; Wang, Weixia; Wang, Hong; Wang, Zhongyuan; Li, Liangliang; Li, Zhihua; Gao, Hongjun; He, Kun; Liu, Xiaoqing

2017-01-01

Background . Diagnoses of malignant pleural effusion (MPE) are a crucial problem in clinics. In our study, we compared the peptide profiles of MPE and tuberculosis pleural effusion (TPE) to investigate the value of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) in diagnosis of MPE. Material and Methods . The 46 MPE and 32 TPE were randomly assigned to training set and validation set. Peptides were isolated by weak cation exchange magnetic beads and peaks in the m / z range of 800-10000 Da were analyzed. Comparing the peptide profile between 30 MPE and 22 TPE samples in training set by ClinProTools software, we screened the specific biomarkers and established a MALDI-TOF-MS classification of MPE. Finally, the other 16 MPE and 10 TPE were included to verify the model. We additionally determined carcinoembryonic antigen (CEA) in MPE and TPE samples using electrochemiluminescent immunoassay method. Results . Five peptide peaks (917.37 Da, 4469.39 Da, 1466.5 Da, 4585.21 Da, and 3216.87 Da) were selected to separate MPE and TPE by MALDI-TOF-MS. The sensitivity, specificity, and accuracy of the classification were 93.75%, 100%, and 96.15%, respectively, after blinded test. The sensitivity of CEA was significantly lower than MALDI-TOF-MS classification ( P = 0.035). Conclusions . The results indicate MALDI-TOF-MS is a potential method for diagnosing MPE.

Evaluation of Hydrodynamic Chromatography Coupled with UV-Visible, Fluorescence and Inductively Coupled Plasma Mass Spectrometry Detectors for Sizing and Quantifying Colloids in Environmental Media

PubMed Central

Philippe, Allan; Schaumann, Gabriele E.

2014-01-01

In this study, we evaluated hydrodynamic chromatography (HDC) coupled with inductively coupled plasma mass spectrometry (ICP-MS) for the analysis of nanoparticles in environmental samples. Using two commercially available columns (Polymer Labs-PDSA type 1 and 2), a set of well characterised calibrants and a new external time marking method, we showed that flow rate and eluent composition have few influence on the size resolution and, therefore, can be adapted to the sample particularity. Monitoring the agglomeration of polystyrene nanoparticles over time succeeded without observable disagglomeration suggesting that even weak agglomerates can be measured using HDC. Simultaneous determination of gold colloid concentration and size using ICP-MS detection was validated for elemental concentrations in the ppb range. HDC-ICP-MS was successfully applied to samples containing a high organic and ionic background. Indeed, online combination of UV-visible, fluorescence and ICP-MS detectors allowed distinguishing between organic molecules and inorganic colloids during the analysis of Ag nanoparticles in synthetic surface waters and TiO2 and ZnO nanoparticles in commercial sunscreens. Taken together, our results demonstrate that HDC-ICP-MS is a flexible, sensitive and reliable method to measure the size and the concentration of inorganic colloids in complex media and suggest that there may be a promising future for the application of HDC in environmental science. Nonetheless the rigorous measurements of agglomerates and of matrices containing natural colloids still need to be studied in detail. PMID:24587393

Evaluation of hydrodynamic chromatography coupled with UV-visible, fluorescence and inductively coupled plasma mass spectrometry detectors for sizing and quantifying colloids in environmental media.

PubMed

Philippe, Allan; Schaumann, Gabriele E

2014-01-01

In this study, we evaluated hydrodynamic chromatography (HDC) coupled with inductively coupled plasma mass spectrometry (ICP-MS) for the analysis of nanoparticles in environmental samples. Using two commercially available columns (Polymer Labs-PDSA type 1 and 2), a set of well characterised calibrants and a new external time marking method, we showed that flow rate and eluent composition have few influence on the size resolution and, therefore, can be adapted to the sample particularity. Monitoring the agglomeration of polystyrene nanoparticles over time succeeded without observable disagglomeration suggesting that even weak agglomerates can be measured using HDC. Simultaneous determination of gold colloid concentration and size using ICP-MS detection was validated for elemental concentrations in the ppb range. HDC-ICP-MS was successfully applied to samples containing a high organic and ionic background. Indeed, online combination of UV-visible, fluorescence and ICP-MS detectors allowed distinguishing between organic molecules and inorganic colloids during the analysis of Ag nanoparticles in synthetic surface waters and TiO₂ and ZnO nanoparticles in commercial sunscreens. Taken together, our results demonstrate that HDC-ICP-MS is a flexible, sensitive and reliable method to measure the size and the concentration of inorganic colloids in complex media and suggest that there may be a promising future for the application of HDC in environmental science. Nonetheless the rigorous measurements of agglomerates and of matrices containing natural colloids still need to be studied in detail.

Classification of organic aerosol in the atmosphere over Seoul based on chemical group separation using two dimensional gas chromatography-time of flight mass spectrometry (GC×GC TOFMS) data

NASA Astrophysics Data System (ADS)

Jeon, S.; Lim, H. B.; Choi, N.; Lee, J.; Ahn, Y. K.; Kim, Y. P.

2016-12-01

Organic aerosols contain thousands of organic compounds and contribute to 20-90% of the total fine aerosol mass. For analyzing organic aerosols, a wide range of analytical techniques have been used such as gas chromatography mass spectrometer (GC/MS), liquid chromatography mass spectrometer (LC/MS), aerosol mass spectrometer (AMS), etc. Among them, comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometer (GCxGC/TOF-MS) can provide higher chemical resolution than AMS and analyze more mass fractions of organic aerosols than GC/MS. In this study, we suggest a new data processing method using GCxGC/TOF-MS data for analyzing organic compounds in the ambient aerosols. TSP samples were collected on the roof of the Asan engineering building, Ewha Womans University, Seoul, South Korea (37.56 °N, 126.94 °E, 20 m above ground level). A total of 67 samples were obtained during summer (August 2013) and winter (January and February 2014) with a PUF sampler (Tisch, TE-1000) on quartz fiber filter. Filters were extracted using accelerated solvent extractor with a mixture of dichloromethane and methanol (3:1, v/v). Total extracts were blown down to 0.5 mL using a nitrogen evaporator (Turbo Vap Ⅱ, caliper Life Sciences). Organic compounds in the TSP samples were separated into 6 chemical groups, depending on their retention time in two dimensions for their volatility and polarity. All area of peaks in each group was summed and variance of total area in each group was compared depending on season and diurnal cycle.

High Resolution PTR-TOFMS: A New Instrument for Organic Compound Measurements

NASA Astrophysics Data System (ADS)

Hansel, A.; Graus, M.; Mueller, M.; Wisthaler, A.

2007-12-01

Over the last decade proton transfer reaction mass spectrometry (PTR-MS) has become very popular in many scientific fields. PTR-MS allows for the quantitative detection of volatile organic compounds (VOCs) at pptv-level virtually in real time. Monitoring of VOCs with a time resolution of typically a second per compound has, for instance, enabled the tracking of pollution plumes by air-borne measurements, thus revealing the photo- chemical fate of pollutants. It has also been employed in direct eddy covariant flux measurements. This rapidity, however, has been achieved at the cost of the number of compounds to be analyzed and compound selectivity. Conventional PTR-MS can, for example, not distinguish between hydrocarbons and their oxygenated isobaric species, e.g. between naphthalene and octanal or between isoprene and furan. In a mass range up to 200 Dalton, such a task would require a mass resolving power of 5500. The use of a time of flight (TOF) instead of a quadrupole mass analyzer in PTR-MS provides a sufficient high mass resolution to identify the atomic composition of product ions by their exact mass and their characteristic isotope patterns. In addition PTR-TOF-MS can record full mass spectra within a fraction of a second which is a dramatically increase in duty cycle. At the University of Innsbruck a high resolution PTR-TOFMS has recently been developed, coupling a PTR-ion source and a high resolution TOFMS. We achieved a mass resolving power of 6000 (FWHM), and a detection limit of tens to a few hundreds of pptv if integrating mass spectra for one minute. First results and future directions will be discussed in this paper.

A Novel Molecular Microbiologic Technique for the Rapid Diagnosis of Microbial Invasion of the Amniotic Cavity and Intra-Amniotic Infection in Preterm Labor with Intact Membranes

PubMed Central

Romero, Roberto; Miranda, Jezid; Chaiworapongsa, Tinnakorn; Chaemsaithong, Piya; Gotsch, Francesca; Dong, Zhong; Ahmed, Ahmed I.; Yoon, Bo Hyun; Hassan, Sonia; Kim, Chong J.; Korzeniewski, Steven J.; Yeo, Lami

2014-01-01

Objective The major challenges in using amniotic fluid (AF) cultivation techniques to diagnose microbial invasion of the amniotic cavity (MIAC) are: 1) several days are typically required to obtain results, and 2) many organisms implicated in the pathogenesis of human disease are difficult to culture. Here, we compare the performance of AF culture with a novel technique for the diagnosis of MIAC that can provide results within eight hours by combining broad-range real-time polymerase chain reaction with electrospray ionization mass spectrometry (PCR/ESI-MS) to identify and quantify genomic material from bacteria and viruses in AF. Methods AF samples obtained by transabdominal amniocentesis from 142 women with preterm labor (PTL) and intact membranes were analyzed using cultivation techniques (aerobic, anaerobic and genital mycoplasmas) as well as PCR/ESI-MS. The prevalence and relative magnitude of intra-amniotic inflammation [AF Interleukin 6 (IL-6) concentration ≥ 2.6 ng/mL], acute histologic chorioamnionitis, spontaneous preterm delivery, and perinatal mortality were examined according to the results of these two tests. Results 1) The prevalence of MIAC in patients with preterm labor and intact membranes was 7% using standard cultivation techniques and 12% using PCR/ESI-MS; 2) seven of ten patients with positive AF culture also had positive PCR/ESI-MS [≥17 genome equivalents per PCR reaction well (GE/well)] 3) patients with positive PCR/ESI-MS (≥17 GE/well) and negative AF cultures had significantly higher rates of intra-amniotic inflammation and histologic acute chorioamnionitis, shorter intervals to delivery [median (interquartile range-IQR)], and offspring at higher risk of perinatal mortality, than women with both tests negative [90% (9/10) vs. 32% (39/122); (p<0.001); 70% (7/10) vs. 35% (39/112); (p=0.04); 1 (IQR: <1 – 2) days vs. 25 (IQR: 5 – 51) days; (p=0.002); OR: 5.6; 95% CI: 1.4 – 22, respectively]; 5) there were no significant differences in these factors between patients with positive PCR/ESI-MS (≥17 GE/well) who had negative AF cultures compared to those with positive AF cultures; and 6) PCR/ESI-MS detected genomic material from viruses in two patients (1.4%). Conclusion 1) Rapid diagnosis of intra-amniotic infection is possible using PCR/ESI-MS, which can provide results within 8 hours; 2) the combined use of biomarkers of inflammation and PCR/ESI-MS allows for the rapid identification of specific bacteria and viruses in women with preterm labor and intra-amniotic infection; and 3) this approach may allow for administration of timely and specific interventions to reduce morbidity attributed to infection-induced preterm birth. PMID:24417618

On-line supercritical fluid extraction-supercritical fluid chromatography-mass spectrometry of polycyclic aromatic hydrocarbons in soil.

PubMed

Wicker, A Paige; Carlton, Doug D; Tanaka, Kenichiro; Nishimura, Masayuki; Chen, Vivian; Ogura, Tairo; Hedgepeth, William; Schug, Kevin A

2018-06-01

On-line supercritical fluid extraction - supercritical fluid chromatography - mass spectrometry (SFE-SFC-MS) has been applied for the determination of polycyclic aromatic hydrocarbons (PAHs) in soil. The purpose of this study was to develop and validate the first on-line SFE-SFC-MS method for the quantification of PAHs in various types of soil. By coupling the sample extraction on-line with chromatography and detection, sample preparation is minimized, diminishing sample loss and contamination, and significantly decreasing the required extraction time. Parameters for on-line extraction coupled to chromatographic analysis were optimized. The method was validated for concentrations of 10-1500 ng of PAHs per gram of soil in Certified Reference Material (CRM) sediment, clay, and sand with R 2  ≥ 0.99. Limits of detection (LOD) were found in the range of 0.001-5 ng/g, and limits of quantification (LOQ) in the range of 5-15 ng/g. The method developed in this study can be effectively applied to the study of PAHs in the environment, and may lay the foundation for further applications of on-line SFE-SFC-MS. Copyright © 2018 Elsevier B.V. All rights reserved.

Characterization, stoichiometry, and stability of salivary protein-tannin complexes by ESI-MS and ESI-MS/MS.

PubMed

Canon, Francis; Paté, Franck; Meudec, Emmanuelle; Marlin, Thérèse; Cheynier, Véronique; Giuliani, Alexandre; Sarni-Manchado, Pascale

2009-12-01

Numerous protein-polyphenol interactions occur in biological and food domains particularly involving proline-rich proteins, which are representative of the intrinsically unstructured protein group (IUP). Noncovalent protein-ligand complexes are readily detected by electrospray ionization mass spectrometry (ESI-MS), which also gives access to ligand binding stoichiometry. Surprisingly, the study of interactions between polyphenolic molecules and proteins is still an area where ESI-MS has poorly benefited, whereas it has been extensively applied to the detection of noncovalent complexes. Electrospray ionization mass spectrometry has been applied to the detection and the characterization of the complexes formed between tannins and a human salivary proline-rich protein (PRP), namely IB5. The study of the complex stability was achieved by low-energy collision-induced dissociation (CID) measurements, which are commonly implemented using triple quadrupole, hybrid quadrupole time-of-flight, or ion trap instruments. Complexes composed of IB5 bound to a model polyphenol EgCG have been detected by ESI-MS and further analyzed by MS/MS. Mild ESI interface conditions allowed us to observe intact noncovalent PRP-tannin complexes with stoichiometries ranging from 1:1 to 1:5. Thus, ESI-MS shows its efficiency for (1) the study of PRP-tannin interactions, (2) the determination of stoichiometry, and (3) the study of complex stability. We were able to establish unambiguously both their stoichiometries and their overall subunit architecture via tandem mass spectrometry and solution disruption experiments. Our results prove that IB5.EgCG complexes are maintained intact in the gas phase.

Development of an online SPE-UHPLC-MS/MS method for the multiresidue analysis of the 17 compounds from the EU "Watch list".

PubMed

Gusmaroli, Lucia; Insa, Sara; Petrovic, Mira

2018-04-24

During the last decades, the quality of aquatic ecosystems has been threatened by increasing levels of pollutions, caused by the discharge of man-made chemicals, both via accidental release of pollutants as well as a consequence of the constant outflow of inadequately treated wastewater effluents. For this reason, the European Union is updating its legislations with the aim of limiting the release of emerging contaminants. The Commission Implementing Decision (EU) 2015/495 published in March 2015 drafts a "Watch list" of compounds to be monitored Europe-wide. In this study, a methodology based on online solid-phase extraction (SPE) ultra-high-performance liquid chromatography coupled to a triple-quadrupole mass spectrometer (UHPLC-MS/MS) was developed for the simultaneous determination of the 17 compounds listed therein. The proposed method offers advantages over already available methods, such as versatility (all 17 compounds can be analyzed simultaneously), shorter time required for analysis, robustness, and sensitivity. The employment of online sample preparation minimized sample manipulation and reduced dramatically the sample volume needed and time required, dramatically the sample volume needed and time required, thus making the analysis fast and reliable. The method was successfully validated in surface water and influent and effluent wastewater. Limits of detection ranged from sub- to low-nanogram per liter levels, in compliance with the EU limits, with the only exception of EE2. Graphical abstract Schematic of the workflow for the analysis of the Watch list compounds.

Discrete prepotential as an indicator of successful ablation in patients with coronary cusp ventricular arrhythmia.

PubMed

Hachiya, Hitoshi; Yamauchi, Yasuteru; Iesaka, Yoshito; Yagishita, Atsuhiko; Sasaki, Takeshi; Higuchi, Koji; Kawabata, Mihoko; Sugiyama, Koji; Tanaka, Yasuaki; Kusa, Shigeki; Nakamura, Hiroaki; Miyazaki, Shinsuke; Taniguchi, Hiroshi; Isobe, Mitsuaki; Hirao, Kenzo

2013-10-01

Although coronary cusp (CC) ventricular arrhythmia (VA) can be treated by catheter ablation, reliable indicators of successful ablation sites have not been fully identified. This study comprised 392 patients undergoing radiofrequency catheter ablation for outflow tract-VA at 3 institutions from January 2007 to August 2012. The successful ablation site was on the left CC or right CC in 35 (8.9%) of the 392 patients. In 9 (26%) of these 35 patients, a discrete prepotential was recognized, 5 of whom had left CC-VAs and 4 of whom had right CC-VAs. Radiofrequency catheter ablation was successful at the site of the prepotential in all 9 of these patients. The duration of the isoelectric line between the end of the discrete prepotential and the onset of the ventricular electrogram was 27±13 ms. The time from onset of the discrete prepotential at the successful ablation site on the CC to the QRS onset (activation time) was 69±20 ms (range, 50-98 ms). Pace mapping was graded as excellent at the successful ablation site in only 1 patient. No discrete prepotential was recorded in any successful right outflow tract-VA ablation case in this study. A discrete prepotential was seen in 9 (26%) of 35 patients with CC-VA. In left and right CC-VA, the site of a discrete prepotential with ≥50 ms activation time may indicate a successful ablation site.

Forensic applications of direct analysis in real time (DART) coupled to Q-orbitrap tandem mass spectrometry for the in situ analysis of pigments from paint evidence.

PubMed

Chen, Tai-Hung; Wu, Shu-Pao

2017-08-01

The accurate examination of paint fragments obtained from an accident, such as those obtained from vehicles involved in a hit-and-run case, is often critical in forensic investigations. However, organic pigments are typically minor components of automotive coatings, which makes discrimination difficult. In this study, direct analysis in real time coupled to Q-orbitrap tandem mass spectrometry (DART-MS) was employed to detect a wide range of common organic pigments in vehicle paints. Twelve common organic pigments used in vehicle paints, such as red, yellow, orange, and purple, were tested, and a database was constructed for future examinations of vehicle paint. Two hit-and-run vehicle accident cases, which occurred in New Taipei City, were investigated by Fourier transform infrared (FTIR) spectroscopy and DART-MS. First, FTIR spectroscopy was employed to study the paint samples as a preliminary screening step. Most of the observed IR peaks were attributed to binder and extenders present in paints. The IR peaks corresponding to the organic pigments were found to be weak and overlapped with those corresponding to resins. On the other hand, DART-MS successfully characterized the organic pigments. DART-MS was found to be excellent for rapidly determining the presence of organic pigments in paint samples without the need for a complicated pre-treatment process or lengthy analysis time. Copyright © 2017 Elsevier B.V. All rights reserved.

Multiple Time-of-Flight/Time-of-Flight Events in a Single Laser Shot for Improved Matrix-Assisted Laser Desorption/Ionization Tandem Mass Spectrometry Quantification.

PubMed

Prentice, Boone M; Chumbley, Chad W; Hachey, Brian C; Norris, Jeremy L; Caprioli, Richard M

2016-10-04

Quantitative matrix-assisted laser desorption/ionization time-of-flight (MALDI TOF) approaches have historically suffered from poor accuracy and precision mainly due to the nonuniform distribution of matrix and analyte across the target surface, matrix interferences, and ionization suppression. Tandem mass spectrometry (MS/MS) can be used to ensure chemical specificity as well as improve signal-to-noise ratios by eliminating interferences from chemical noise, alleviating some concerns about dynamic range. However, conventional MALDI TOF/TOF modalities typically only scan for a single MS/MS event per laser shot, and multiplex assays require sequential analyses. We describe here new methodology that allows for multiple TOF/TOF fragmentation events to be performed in a single laser shot. This technology allows the reference of analyte intensity to that of the internal standard in each laser shot, even when the analyte and internal standard are quite disparate in m/z, thereby improving quantification while maintaining chemical specificity and duty cycle. In the quantitative analysis of the drug enalapril in pooled human plasma with ramipril as an internal standard, a greater than 4-fold improvement in relative standard deviation (<10%) was observed as well as improved coefficients of determination (R 2 ) and accuracy (>85% quality controls). Using this approach we have also performed simultaneous quantitative analysis of three drugs (promethazine, enalapril, and verapamil) using deuterated analogues of these drugs as internal standards.

Broad Detection Range Rhenium Diselenide Photodetector Enhanced by (3-Aminopropyl)Triethoxysilane and Triphenylphosphine Treatment.

PubMed

Jo, Seo-Hyeon; Park, Hyung-Youl; Kang, Dong-Ho; Shim, Jaewoo; Jeon, Jaeho; Choi, Seunghyuk; Kim, Minwoo; Park, Yongkook; Lee, Jaehyeong; Song, Young Jae; Lee, Sungjoo; Park, Jin-Hong

2016-08-01

The effects of triphenylphosphine and (3-aminopropyl)triethoxysilane on a rhenium diselenide (ReSe2 ) photodetector are systematically studied by comparing with conventional MoS2 devices. This study demonstrates a very high performance ReSe2 photodetector with high photoresponsivity (1.18 × 10(6) A W(-1) ), fast photoswitching speed (rising/decaying time: 58/263 ms), and broad photodetection range (possible above 1064 nm). © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Method development for mass spectrometry based molecular characterization of fossil fuels and biological samples

NASA Astrophysics Data System (ADS)

Mahat, Rajendra K.

In an analytical (chemical) method development process, the sample preparation step usually determines the throughput and overall success of the analysis. Both targeted and non-targeted methods were developed for the mass spectrometry (MS) based analyses of fossil fuels (coal) and lipidomic analyses of a unique micro-organism, Gemmata obscuriglobus. In the non-targeted coal analysis using GC-MS, a microwave-assisted pressurized sample extraction method was compared with the traditional extraction method, such as Soxhlet. On the other hand, methods were developed to establish a comprehensive lipidomic profile and to confirm the presence of endotoxins (a.k.a. lipopolysaccharides, LPS) in Gemmata.. The performance of pressurized heating techniques employing hot-air oven and microwave irradiation were compared with that of Soxhlet method in terms of percentage extraction efficiency and extracted analyte profiles (via GC-MS). Sub-bituminous (Powder River Range, Wyoming, USA) and bituminous (Fruitland formation, Colorado, USA) coal samples were tested. Overall 30-40% higher extraction efficiencies (by weight) were obtained with a 4 hour hot-air oven and a 20 min microwave-heating extraction in a pressurized container when compared to a 72 hour Soxhlet extraction. The pressurized methods are 25 times more economic in terms of solvent/sample amount used and are 216 times faster in term of time invested for the extraction process. Additionally, same sets of compounds were identified by GC-MS for all the extraction methods used: n-alkanes and diterpanes in the sub-bituminous sample, and n-alkanes and alkyl aromatic compounds in the bituminous coal sample. G. obscuriglobus, a nucleated bacterium, is a micro-organism of high significances from evolutionary, cell and environmental biology standpoints. Although lipidomics is an essential tool in microbiological systematics and chemotaxonomy, complete lipid profile of this bacterium is still lacking. In addition, the presence of LPS and thus outer membrane (OM) in Gemmata is unknown. Global lipidomic analysis of G. obscuriglobus showed fatty acids (FAs) in the range C14 - C22, with octadecanoic and cis-9 hexadecenoic acids (C18:0 and ωc9 C16:1) being the two most abundant FAs. Thirteen different Gram-negative specific 3-hydroxy fatty acids (3-HOFAs) and eukaryote specific sterols (C30; four in number) were identified. Additionally, like a eukaryotic cell, a polyunsaturated fatty acid (PUFA; tent. ω3 C27:3) has also been discovered. The targeted lipidomic study found a series of novel biomarkers in G. obscuriglobus. Compositional analysis of LPS confirmed eight different 3-HOFAs and a sugar-acid, 2-keto 3-deoxy-D-manno -octulosonic acid (Kdo). These two groups of compounds, being unique to a Gram-negative LPS, confirmed the presence of OM in G. obscuriglobus. Moreover, compositional analyses by GC-MS also confirmed glucosamine and hexose and heptose sugars in the LPS. These compositional information obtained from GC-MS analyses were combined with molecular/structural information collected from Matrix-assisted laser desorption and ionization-time of flight (MALDI-TOF) MS. The MALDI-TOF MS showed a cluster of ions separated by 14 u, from m/z 2017.16 to 2143.28. For the most intense ion at m/z 2087.22, a tentative hexa-acylated lipid A structure has been proposed. Identifications of multiple 3-HOFAs by GC-MS and a cluster of ions in MALDI suggest presence of multiple lipid A species, i.e., heterogeneous lipid A molecule, in G. obscuriglobus..

Rapid Quantification of N-Methyl-2-pyrrolidone in Polymer Matrices by Thermal Desorption-GC/MS.

PubMed

Kim, Young-Min; Kim, Jae Woo; Moon, Hye Mi; Lee, Min-Jin; Hosaka, Akihiko; Watanabe, Atsushi; Teramae, Norio; Park, Young-Kwon; Myung, Seung-Woon

2017-01-01

Analysis of a residual solvent in polymeric materials has become an important issue due to the increased regulations and standards for its use. N-Methyl-2-pyrrolidone (NMP) is a solvent widely used in many industries and restricted as one of the chemicals under EU REACH regulations due to its potential harmful effects. In this study, thermal desorption-gas chromatography/mass spectrometry (TD-GC/MS) is applied for the quantitative analysis of NMP with the use of a polymer-coated sample cup. By using the polymer-coated sample cup, the vaporization of NMP was prevented during waiting time before TD-GC/MS analysis. The calibration curve for the TD method showed good linearity (correlation coefficient, r 2 = 0.9998) and precision values (below 5.3% RSD). NMP recovery rates in different polymer matrices (PS, PMMA and PVC) were in the range of 98.8 to 106.6% with RSD values below 5.0%. The quantification result (600 mg NMP/kg PVC) for the blind NMP carrying sample in a PVC matrix by TD-GC/MS was higher than that (532 mg NMP/kg PVC) by solvent extraction-GC/MS method.

Methods to Enhance Laser Speckle Imaging of High-Flow and Low-Flow Vasculature

PubMed Central

Choi, Bernard; Ringold, Tyson L.; Kim, Jeehyun

2012-01-01

The objective of this paper is to present two methods to extend the response range of laser speckle imaging (LSI). We report on the use of two methods (image exposure time control and magnetomotive actuation of exogenous contrast agents) to enhance characterization of high- and low-flow vasculature, respectively. With an exposure time of 10 and 0.01 ms, the linear response range extended to 10 and 280 mm/s, respectively. With application of an AC magnetic field to a solution of stagnant SPIO particles, an apparent increase of ~3× in speckle flow index was induced. PMID:19964103

Improving liquid chromatography-tandem mass spectrometry determinations by modifying noise frequency spectrum between two consecutive wavelet-based low-pass filtering procedures.

PubMed

Chen, Hsiao-Ping; Liao, Hui-Ju; Huang, Chih-Min; Wang, Shau-Chun; Yu, Sung-Nien

2010-04-23

This paper employs one chemometric technique to modify the noise spectrum of liquid chromatography-tandem mass spectrometry (LC-MS/MS) chromatogram between two consecutive wavelet-based low-pass filter procedures to improve the peak signal-to-noise (S/N) ratio enhancement. Although similar techniques of using other sets of low-pass procedures such as matched filters have been published, the procedures developed in this work are able to avoid peak broadening disadvantages inherent in matched filters. In addition, unlike Fourier transform-based low-pass filters, wavelet-based filters efficiently reject noises in the chromatograms directly in the time domain without distorting the original signals. In this work, the low-pass filtering procedures sequentially convolve the original chromatograms against each set of low pass filters to result in approximation coefficients, representing the low-frequency wavelets, of the first five resolution levels. The tedious trials of setting threshold values to properly shrink each wavelet are therefore no longer required. This noise modification technique is to multiply one wavelet-based low-pass filtered LC-MS/MS chromatogram with another artificial chromatogram added with thermal noises prior to the other wavelet-based low-pass filter. Because low-pass filter cannot eliminate frequency components below its cut-off frequency, more efficient peak S/N ratio improvement cannot be accomplished using consecutive low-pass filter procedures to process LC-MS/MS chromatograms. In contrast, when the low-pass filtered LC-MS/MS chromatogram is conditioned with the multiplication alteration prior to the other low-pass filter, much better ratio improvement is achieved. The noise frequency spectrum of low-pass filtered chromatogram, which originally contains frequency components below the filter cut-off frequency, is altered to span a broader range with multiplication operation. When the frequency range of this modified noise spectrum shifts toward the high frequency regimes, the other low-pass filter is able to provide better filtering efficiency to obtain higher peak S/N ratios. Real LC-MS/MS chromatograms, of which typically less than 6-fold peak S/N ratio improvement achieved with two consecutive wavelet-based low-pass filters remains the same S/N ratio improvement using one-step wavelet-based low-pass filter, are improved to accomplish much better ratio enhancement 25-folds to 40-folds typically when the noise frequency spectrum is modified between two low-pass filters. The linear standard curves using the filtered LC-MS/MS signals are validated. The filtered LC-MS/MS signals are also reproducible. The more accurate determinations of very low concentration samples (S/N ratio about 7-9) are obtained using the filtered signals than the determinations using the original signals. Copyright 2010 Elsevier B.V. All rights reserved.

Optimization and application of ICPMS with dynamic reaction cell for precise determination of 44Ca/40Ca isotope ratios.

PubMed

Boulyga, Sergei F; Klötzli, Urs; Stingeder, Gerhard; Prohaska, Thomas

2007-10-15

An inductively coupled plasma mass spectrometer with dynamic reaction cell (ICP-DRC-MS) was optimized for determining (44)Ca/(40)Ca isotope ratios in aqueous solutions with respect to (i) repeatability, (ii) robustness, and (iii) stability. Ammonia as reaction gas allowed both the removal of (40)Ar+ interference on (40)Ca+ and collisional damping of ion density fluctuations of an ion beam extracted from an ICP. The effect of laboratory conditions as well as ICP-DRC-MS parameters such a nebulizer gas flow rate, rf power, lens potential, dwell time, or DRC parameters on precision and mass bias was studied. Precision (calculated using the "unbiased" or "n - 1" method) of a single isotope ratio measurement of a 60 ng g(-1) calcium solution (analysis time of 6 min) is routinely achievable in the range of 0.03-0.05%, which corresponded to the standard error of the mean value (n = 6) of 0.012-0.020%. These experimentally observed RSDs were close to theoretical precision values given by counting statistics. Accuracy of measured isotope ratios was assessed by comparative measurements of the same samples by ICP-DRC-MS and thermal ionization mass spectrometry (TIMS) by using isotope dilution with a (43)Ca-(48)Ca double spike. The analysis time in both cases was 1 h per analysis (10 blocks, each 6 min). The delta(44)Ca values measured by TIMS and ICP-DRC-MS with double-spike calibration in two samples (Ca ICP standard solution and digested NIST 1486 bone meal) coincided within the obtained precision. Although the applied isotope dilution with (43)Ca-(48)Ca double-spike compensates for time-dependent deviations of mass bias and allows achieving accurate results, this approach makes it necessary to measure an additional isotope pair, reducing the overall analysis time per isotope or increasing the total analysis time. Further development of external calibration by using a bracketing method would allow a wider use of ICP-DRC-MS for routine calcium isotopic measurements, but it still requires particular software or hardware improvements aimed at reliable control of environmental effects, which might influence signal stability in ICP-DRC-MS and serve as potential uncertainty sources in isotope ratio measurements.

T2 relaxation times of the glenohumeral joint at 3.0 T MRI in patients with and without primary and secondary osteoarthritis.

PubMed

Lee, So-Yeon; Park, Hee-Jin; Kwon, Heon-Ju; Kim, Mi Sung; Choi, Seon Hyeong; Choi, Yoon Jung; Kim, Eugene

2015-11-01

Quantitative magnetic resonance imaging (MRI) of cartilage has recently been applied to patients with osteoarthritis (OA). T2 mapping is a sensitive method of detecting changes in the chemical composition and structure of cartilage. To establish baseline T2 values of glenohumeral joint cartilage at 3.0 T and compare T2 values among subjects with and without OA. The study involved 30 patients (18 women, 12 men; median age, 67 years; age range, 51-78 years) with primary (n = 7) and secondary OA (n = 23) in the glenohumeral joint and 34 subjects without OA (19 women, 15 men; median age, 49 years; age range, 23-63 years). All subjects were evaluated by radiography and 3.0 T MRI including a multi-echo T2-weighted spin echo pulse sequence. The T2 value of the cartilage was measured by manually drawing the region of interest on the T2 map. Per-zone comparison of T2 values was performed using Mann-Whitney U test. Median T2 values differed significantly between subjects without OA (36.00 ms [interquartile range, 33.89-37.31 ms]) and those with primary (37.52 ms [36.84-39.11], P = 0.028), but not secondary (36.87 ms [34.70-41.10], P = 0.160) OA. Glenohumeral cartilage T2 values were higher in different zones between patients with primary and secondary OA than in subjects without OA. These T2 values can be used for comparison to assess cartilage degeneration in patients with shoulder OA. Significant differences in T2 were observed among subjects without OA and those with primary and secondary OA. © The Foundation Acta Radiologica 2014.

Development of a new multi-residue laser diode thermal desorption atmospheric pressure chemical ionization tandem mass spectrometry method for the detection and quantification of pesticides and pharmaceuticals in wastewater samples.

PubMed

Boisvert, Michel; Fayad, Paul B; Sauvé, Sébastien

2012-11-19

A new solid phase extraction (SPE) method coupled to a high throughput sample analysis technique was developed for the simultaneous determination of nine selected emerging contaminants in wastewater (atrazine, desethylatrazine, 17β-estradiol, ethynylestradiol, norethindrone, caffeine, carbamazepine, diclofenac and sulfamethoxazole). We specifically included pharmaceutical compounds from multiple therapeutic classes, as well as pesticides. Sample pre-concentration and clean-up was performed using a mixed-mode SPE cartridge (Strata ABW) having both cation and anion exchange properties, followed by analysis by laser diode thermal desorption atmospheric pressure chemical ionization coupled to tandem mass spectrometry (LDTD-APCI-MS/MS). The LDTD interface is a new high-throughput sample introduction method, which reduces total analysis time to less than 15s per sample as compared to minutes with traditional liquid-chromatography coupled to tandem mass spectrometry (LC-MS/MS). Several SPE parameters were evaluated in order to optimize recovery efficiencies when extracting analytes from wastewater, such as the nature of the stationary phase, the loading flow rate, the extraction pH, the volume and composition of the washing solution and the initial sample volume. The method was successfully applied to real wastewater samples from the primary sedimentation tank of a municipal wastewater treatment plant. Recoveries of target compounds from wastewater ranged from 78% to 106%, the limit of detection ranged from 30 to 122ng L(-1) while the limit of quantification ranged from 90 to 370ng L(-1). Calibration curves in the wastewater matrix showed good linearity (R(2)≥0.991) for all target analytes and the intraday and interday coefficient of variation was below 15%, reflecting a good precision. Copyright © 2012 Elsevier B.V. All rights reserved.

Comprehensive comparison of liquid chromatography selectivity as provided by two types of liquid chromatography detectors (high resolution mass spectrometry and tandem mass spectrometry): "where is the crossover point?".

PubMed

Kaufmann, A; Butcher, P; Maden, K; Walker, S; Widmer, M

2010-07-12

The selectivity of mass traces obtained by monitoring liquid chromatography coupled to high resolution mass spectrometry (LC-HRMS) and liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) was compared. A number of blank extracts (fish, pork kidney, pork liver and honey) were separated by ultra performance liquid chromatography (UPLC). Detected were some 100 dummy transitions respectively dummy exact masses (traces). These dummy masses were the product of a random generator. The range of the permitted masses corresponded to those which are typical for analytes (e.g. veterinary drugs). The large number of monitored dummy traces ensured that endogenous compounds present in the matrix extract, produced a significant number of detectable chromatographic peaks. All obtained chromatographic peaks were integrated and standardized. Standardisation was done by dividing these absolute peak areas by the average response of a set of 7 different veterinary drugs. This permitted a direct comparison between the LC-HRMS and LC-MS/MS data. The data indicated that the selectivity of LC-HRMS exceeds LC-MS/MS, if high resolution mass spectrometry (HRMS) data is recorded with a resolution of 50,000 full width at half maximum (FWHM) and a corresponding mass window. This conclusion was further supported by experimental data (MS/MS based trace analysis), where a false positive finding was observed. An endogenous matrix compound present in honey matrix behaved like a banned nitroimidazole drug. This included identical retention time and two MRM traces, producing an MRM ratio between them, which perfectly matched the ratio observed in the external standard. HRMS measurement clearly resolved the interfering matrix compound and unmasked the false positive MS/MS finding. Copyright 2010 Elsevier B.V. All rights reserved.

Front-End Electron Transfer Dissociation Coupled to a 21 Tesla FT-ICR Mass Spectrometer for Intact Protein Sequence Analysis

NASA Astrophysics Data System (ADS)

Weisbrod, Chad R.; Kaiser, Nathan K.; Syka, John E. P.; Early, Lee; Mullen, Christopher; Dunyach, Jean-Jacques; English, A. Michelle; Anderson, Lissa C.; Blakney, Greg T.; Shabanowitz, Jeffrey; Hendrickson, Christopher L.; Marshall, Alan G.; Hunt, Donald F.

2017-09-01

High resolution mass spectrometry is a key technology for in-depth protein characterization. High-field Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) enables high-level interrogation of intact proteins in the most detail to date. However, an appropriate complement of fragmentation technologies must be paired with FTMS to provide comprehensive sequence coverage, as well as characterization of sequence variants, and post-translational modifications. Here we describe the integration of front-end electron transfer dissociation (FETD) with a custom-built 21 tesla FT-ICR mass spectrometer, which yields unprecedented sequence coverage for proteins ranging from 2.8 to 29 kDa, without the need for extensive spectral averaging (e.g., 60% sequence coverage for apo-myoglobin with four averaged acquisitions). The system is equipped with a multipole storage device separate from the ETD reaction device, which allows accumulation of multiple ETD fragment ion fills. Consequently, an optimally large product ion population is accumulated prior to transfer to the ICR cell for mass analysis, which improves mass spectral signal-to-noise ratio, dynamic range, and scan rate. We find a linear relationship between protein molecular weight and minimum number of ETD reaction fills to achieve optimum sequence coverage, thereby enabling more efficient use of instrument data acquisition time. Finally, real-time scaling of the number of ETD reactions fills during method-based acquisition is shown, and the implications for LC-MS/MS top-down analysis are discussed. [Figure not available: see fulltext.

Rapid determination of 1-deoxynojirimycin in Morus alba L. leaves by direct analysis in real time (DART) mass spectrometry.

PubMed

Xu, Bin; Zhang, Dong-Yang; Liu, Ze-Yu; Zhang, Ying; Liu, Li; Li, Long; Liu, Charles C; Wu, Guo-Hua

2015-10-10

A new method based on a Direct Analysis in Real Time (DART) ionization source coupled with triple quadrupole tandem mass spectrometry has been developed for rapid qualitative and quantitative analyses of 1-deoxynojirimycin (DNJ) in mulberry leaves. Two ions produced from DNJ, [M+H](+) (m/z 164) and [M-2H+H](+) (m/z 162), are observed using DART-MS in the positive ion mode. The peak areas of the two selected ions monitoring (SIM) signals of ([M+H](+) (m/z 164) and [M-2H+H](+) (m/z 162)) are integrated to determine the peak area for quantitative analyses. A reasonable linear regression equation is obtained in the range of 1.01 to 40.50 μg/mL, with a linear coefficient (R(2)) of 0.996. The limits of detection (LOD) and quantification (LOQ) of the method are 0.25 and 0.80 μg/mL, respectively. The range of recovery is shown to be 87.73-95.61%. The results derived from the developed DART-MS method are in good agreement with those from the conventional HPLC-FLD method. By contrast, DART-MS in SIM mode is a simple, rapid and high-throughput approach for the determination of the DNJ content in mulberry leaves. The present method is advantageous for the rapid screening of mulberry leaves containing high DNJ contents. Copyright © 2015 Elsevier B.V. All rights reserved.

A new LC-MS/MS bioanalytical method for atenolol in human plasma and milk.

PubMed

Phyo Lwin, Ei Mon; Gerber, Cobus; Song, Yunmei; Leggett, Catherine; Ritchie, Usha; Turner, Sean; Garg, Sanjay

2017-04-01

A new sensitive LC-MS/MS method for the quantification of atenolol in human plasma and milk has been developed for clinical lactation studies. Atenolol and the internal standard, phenazone, were extracted from biological matrices by protein precipitation. A Phenomenex ® C-18 column and gradient chromatographic conditions were used for separation of the analyte, followed by detection with MS. Stability of samples was confirmed for atenolol in human plasma and milk for up to 3 months. Linearity range of 1-800 ng/ml (r 2 = 0.9995), the precision within 15% CV and the recovery of the analyte (80-100% range) were achieved. A new validated analytical method for atenolol in plasma and milk was developed.

An Effective Semantic Event Matching System in the Internet of Things (IoT) Environment.

PubMed

Alhakbani, Noura; Hassan, Mohammed Mehedi; Ykhlef, Mourad

2017-09-02

IoT sensors use the publish/subscribe model for communication to benefit from its decoupled nature with respect to space, time, and synchronization. Because of the heterogeneity of communicating parties, semantic decoupling is added as a fourth dimension. The added semantic decoupling complicates the matching process and reduces its efficiency. Our proposed algorithm clusters subscriptions and events according to topic and performs the matching process within these clusters, which increases the throughput by reducing the matching time from the range of 16-18 ms to 2-4 ms. Moreover, the accuracy of matching is improved when subscriptions must be fully approximated, as demonstrated by an over 40% increase in F-score results. This work shows the benefit of clustering, as well as the improvement in the matching accuracy and efficiency achieved using this approach.

Depth profiling and imaging capabilities of an ultrashort pulse laser ablation time of flight mass spectrometer

PubMed Central

Cui, Yang; Moore, Jerry F.; Milasinovic, Slobodan; Liu, Yaoming; Gordon, Robert J.; Hanley, Luke

2012-01-01

An ultrafast laser ablation time-of-flight mass spectrometer (AToF-MS) and associated data acquisition software that permits imaging at micron-scale resolution and sub-micron-scale depth profiling are described. The ion funnel-based source of this instrument can be operated at pressures ranging from 10−8 to ∼0.3 mbar. Mass spectra may be collected and stored at a rate of 1 kHz by the data acquisition system, allowing the instrument to be coupled with standard commercial Ti:sapphire lasers. The capabilities of the AToF-MS instrument are demonstrated on metal foils and semiconductor wafers using a Ti:sapphire laser emitting 800 nm, ∼75 fs pulses at 1 kHz. Results show that elemental quantification and depth profiling are feasible with this instrument. PMID:23020378

Formation of nanoscale water bridges

NASA Astrophysics Data System (ADS)

Riedo, Elisa; Szoszkiewicz, Robert; Li, Tai-De; Gao, Jianping; Landman, Uzi

2006-03-01

The water bridges provide stability to sand castles, act as transport channels for dip-pen nanolitography and increase adhesion and friction in micro- and nano- devices such as MEMS. The kinetics of capillary condensation and growth at the nanoscale is studied here using friction force microscopy and molecular dynamics calculations. At 40% relative humidity we find that the meniscus nucleation times increase from 0.7 ms up to 4.2 ms when the temperature decreases from 332 K to 299 K. The nucleation times grow exponentially with the inverse temperature 1/T obeying an Arrhenius law. We obtain a nucleation energy barrier of 7.8*10̂-20˜J and an attempt frequency ranging between 4-250˜GHz, in excellent agreement with theoretical predictions. These results provide direct experimental evidence that capillary condensation is a thermally activated phenomenon.

Tailored liquid chromatography-mass spectrometry analysis improves the coverage of the intracellular metabolome of HepaRG cells.

PubMed

Cuykx, Matthias; Negreira, Noelia; Beirnaert, Charlie; Van den Eede, Nele; Rodrigues, Robim; Vanhaecke, Tamara; Laukens, Kris; Covaci, Adrian

2017-03-03

Metabolomics protocols are often combined with Liquid Chromatography-Mass Spectrometry (LC-MS) using mostly reversed phase chromatography coupled to accurate mass spectrometry, e.g. quadrupole time-of-flight (QTOF) mass spectrometers to measure as many metabolites as possible. In this study, we optimised the LC-MS separation of cell extracts after fractionation in polar and non-polar fractions. Both phases were analysed separately in a tailored approach in four different runs (two for the non-polar and two for the polar-fraction), each of them specifically adapted to improve the separation of the metabolites present in the extract. This approach improves the coverage of a broad range of the metabolome of the HepaRG cells and the separation of intra-class metabolites. The non-polar fraction was analysed using a C18-column with end-capping, mobile phase compositions were specifically adapted for each ionisation mode using different co-solvents and buffers. The polar extracts were analysed with a mixed mode Hydrophilic Interaction Liquid Chromatography (HILIC) system. Acidic metabolites from glycolysis and the Krebs cycle, together with phosphorylated compounds, were best detected with a method using ion pairing (IP) with tributylamine and separation on a phenyl-hexyl column. Accurate mass detection was performed with the QTOF in MS-mode only using an extended dynamic range to improve the quality of the dataset. Parameters with the greatest impact on the detection were the balance between mass accuracy and linear range, the fragmentor voltage, the capillary voltage, the nozzle voltage, and the nebuliser pressure. By using a tailored approach for the intracellular HepaRG metabolome, consisting of three different LC techniques, over 2200 metabolites can be measured with a high precision and acceptable linear range. The developed method is suited for qualitative untargeted LC-MS metabolomics studies. Copyright © 2017 Elsevier B.V. All rights reserved.

HINDERED DIFFUSION OF ASPHALTENES AT EVALUATED TEMPERATURE AND PRESSURE

DOE Office of Scientific and Technical Information (OSTI.GOV)

JAMES A. GUIN; SURYA VADLAMANI

1998-10-03

During this time period, the PhD student working on this project, Mr. X. Yang, graduated and has obtained employment with Michelin Tire Company in their research and development laboratory. A new MS student, Mr. Surya Vadlamani, is now working on the project. The work conducted in this time period will form part of Mr. Vadlamani�s MS thesis. Also during the current time period, a no-cost extension was obtained for the project, which will allow Mr. Vadlamani to complete the research work required for the MS degree in chemical engineering. Since Mr. Vadlamani was new to the project and in ordermore » to provide appropriate training, it was necessary to conduct some experimental work in the same ranges as performed earlier by Mr. Yang in order to provide continuity and insure duplication of the experimental data. The new data obtained by Mr. Vadlamani agree well in general with the earlier data obtained by Mr. Yang and extend the earlier data to a higher temperature range. Specifically, during this time period, uptake experiments were performed at temperatures from 25 0 C to 300 o C for the adsorptive diffusion of quinoline in cyclohexane and mineral oil onto alumina catalyst pellets. These experiments were conducted in a 40 cm 3 microautoclave, as contrasted with the previous work done in the much larger 1-liter autoclave. The use of the microautoclave is more economical from both a purchasing and waste disposal standpoint due to the small quantities of solvents and catalysts utilized, and is also significantly safer at the higher temperatures. Model simulation results showed that the mathematical model incorporating diffusion and adsorption mechanisms satisfactorily fitted the adsorptive diffusion of quinoline onto the alumina catalyst in a fairly wide temperature range of 25 o C to 300 o C. The logarithm of the adsorption constant, obtained by simulating the experimental data with the model solution, was found to be linearly dependent on temperature. The data obtained using the microautoclave agreed well with the previous data obtained using the larger 1-liter autoclave.« less

Development and application of a UPLC-MS/MS method for the pharmacokinetic study of 10-hydroxy camptothecin and hydroxyethyl starch conjugate in rats.

PubMed

Li, Guofei; Cai, Cuifang; Ren, Tianyang; Tang, Xing

2014-01-01

With the purpose to carry out the pharmacokinetic studies of 10-hydroxy camptothecin (10-HCPT) and hydroxyethyl starch (10-HCPT-HES) conjugate, an ultraperformance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method has been developed and validated. The analytes, 10-HCPT and the internal standard, Diphenhydramine hydrochloride were extracted with ethyl acetate-isopropanol (95:5, v/v) and separated on an ACQUITY UPLC™ BEH C18 column using a mobile phase composed of acetonitrile and water (containing 0.1% formic acid) with a linear gradient program. With positive ion electrospray ionization (ESI), the analytes were monitored on a triple quadrupole mass spectrometer in the multiple reaction monitoring (MRM) mode. Linear calibration curves were obtained over the concentration ranges of 0.5-2500ng/mL. The intra- and inter-day precisions were less than 9.8% and 10.8%, respectively. The accuracy was within 12.1%. The mean recoveries of 10-HCPT at three concentrations of 2.5, 100, 2000ng/mL were higher than 87.2%. Commercial 10-HCPT injection and 10-HCPT-HES conjugate were administered intravenously at an equal dose of 10-HCPT at 0.5mg/kg. The biological half-life of conjugate was increased significantly from 10min to 3.15h and the bioavailability was 40 times higher than 10-HCPT injection. Consequently, the proposed UPLC-ESI-MS/MS method was proved to be sensitive, specific and reliable to analyze 10-HCPT in biological samples; 10-HCPT and HES conjugate is a promising strategy for delivery of 10-HCPT with prolonged half time and improved bioavailability. Copyright © 2013 Elsevier B.V. All rights reserved.

Solid-phase extraction followed by liquid chromatography quadrupole time-of-flight tandem mass spectrometry for the selective determination of fungicides in wine samples.

PubMed

Fontana, A R; Rodríguez, I; Ramil, M; Altamirano, J C; Cela, R

2011-04-22

In this work, a reliable and selective procedure for the determination of thirteen fungicides in red and white wine samples is proposed. Solid-phase extraction (SPE) and liquid chromatography (LC) tandem mass spectrometry (MS/MS), based on a hybrid quadrupole time-of-flight (QTOF) system, were used as sample preparation and determination techniques, respectively. Extraction and purification of target analytes was carried out simultaneously by using a reversed-phase Oasis HLB (200mg) SPE cartridge combined with acetonitrile as elution solvent. Fungicides were determined operating the electrospray source in the positive ionization mode, with MS/MS conditions adjusted to obtain at least two intense product ions per compound, or registering two transitions per species when a single product was noticed. High selective MS/MS chromatograms were extracted using a mass window of 20 ppms for each product ion. Considering external calibration as quantification technique, the overall recoveries (accuracy) of the procedure ranged between 81% and 114% for red and white wine samples (10-20 mL), spiked at different concentrations between 5 and 100 ng mL(-1). Relative standard deviations of the above data stayed below 12% and the limits of quantification (LOQs) of the method, calculated for 10 mL of wine, varied between 0.1 ng mL(-1) for cyprodinil (CYP) and 0.7 ng mL(-1) for myclobutanil (MYC). The optimized method was applied to seventeen commercial wines produced in Spain and obtained from local supermarkets. Nine fungicides were determined, at levels above the LOQs of the method, in the above samples. The maximum concentrations and the highest occurrence frequencies corresponded to metalaxyl (MET) and iprovalicarb (IPR). Copyright © 2011 Elsevier B.V. All rights reserved.

On an Aerodynamic Mechanism to Enhance Ion Transmission and Sensitivity of FAIMS for Nano-Electrospray Ionization-Mass Spectrometry

NASA Astrophysics Data System (ADS)

Prasad, Satendra; Belford, Michael W.; Dunyach, Jean-Jacques; Purves, Randy W.

2014-12-01

Simulations show that significant ion losses occur within the commercial electrospray ionization-field asymmetric waveform ion mobility spectrometer (ESI-FAIMS) interface owing to an angular desolvation gas flow and because of the impact of the FAIMS carrier gas onto the inner rf (radio frequency) electrode. The angular desolvation gas flow diverts ions away from the entrance plate orifice while the carrier gas annihilates ions onto the inner rf electrode. A novel ESI-FAIMS interface is described that optimizes FAIMS gas flows resulting in large improvements in transmission. Simulations with the bromochloroacetate anion showed an improvement of ~9-fold to give ~70% overall transmission). Comparable transmission improvements were attained experimentally for six peptides (2+) in the range of m/z 404.2 to 653.4 at a chromatographic flow rate of 300 nL/min. Selected ion chromatograms (SIC) from nano-LC-FAIMS-MS analyses showed 71% (HLVDEPQNLIK, m/z 653.4, 2+) to 95% (LVNELTEFAK, m/z 582.3, 2+) of ion signal compared with ion signal in the SIC from LC-MS analysis. IGSEVYHNLK (580.3, 2+) showed 24% more ion signal compared with LC-MS and is explained by enhanced desolvation in FAIMS. A 3-10 times lower limits of quantitation (LOQ) (<15% RSD) was achieved for chemical noise limited peaks with FAIMS. Peaks limited by ion statistics showed subtle improvement in RSD and yielded comparable LOQ to that attained with nano-LC-MS (without FAIMS). These improvements were obtained using a reduced FAIMS separation gap (from 2.5 to 1.5 mm) that results in a shorter residence time (13.2 ms ± 3.9 ms) and enables the use of a helium free transport gas (100% nitrogen).

GlycReSoft: A Software Package for Automated Recognition of Glycans from LC/MS Data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maxwell, Evan; Tan, Yan; Tan, Yuxiang

2012-09-26

Glycosylation modifies the physicochemical properties and protein binding functions of glycoconjugates. These modifications are biosynthesized in the endoplasmic reticulum and Golgi apparatus by a series of enzymatic transformations that are under complex control. As a result, mature glycans on a given site are heterogeneous mixtures of glycoforms. This gives rise to a spectrum of adhesive properties that strongly influences interactions with binding partners and resultant biological effects. In order to understand the roles glycosylation plays in normal and disease processes, efficient structural analysis tools are necessary. In the field of glycomics, liquid chromatography/mass spectrometry (LC/MS) is used to profile themore » glycans present in a given sample. This technology enables comparison of glycan compositions and abundances among different biological samples, i.e. normal versus disease, normal versus mutant, etc. Manual analysis of the glycan profiling LC/MS data is extremely time-consuming and efficient software tools are needed to eliminate this bottleneck. In this work, we have developed a tool to computationally model LC/MS data to enable efficient profiling of glycans. Using LC/MS data deconvoluted by Decon2LS/DeconTools, we built a list of unique neutral masses corresponding to candidate glycan compositions summarized over their various charge states, adducts and range of elution times. Our work aims to provide confident identification of true compounds in complex data sets that are not amenable to manual interpretation. This capability is an essential part of glycomics work flows. We demonstrate this tool, GlycReSoft, using an LC/MS dataset on tissue derived heparan sulfate oligosaccharides. The software, code and a test data set are publically archived under an open source license.« less

Transient impairment of olfactory threshold in acute multiple sclerosis relapse.

PubMed

Bsteh, Gabriel; Hegen, Harald; Ladstätter, Felix; Berek, Klaus; Amprosi, Matthias; Wurth, Sebastian; Auer, Michael; Di Pauli, Franziska; Deisenhammer, Florian; Lutterotti, Andreas; Berger, Thomas

2018-05-18

Impairment of olfactory threshold is a feature of early and active relapsing remitting multiple sclerosis (RRMS). It predicts inflammatory disease activity and was reported to be transient. However, the timing of onset and resolve of olfactory threshold impairment remains unclear. To prospectively assess the development of olfactory threshold in acute MS relapse over time in comparison to stable MS patients. In a prospective observational design, we measured olfactory threshold by performing the Sniffin' Sticks test (minimum score 0, maximum score 16 reflecting optimal olfactory function) at baseline and after 4, 12 and 24 weeks. We included 30 RRMS patients with acute MS relapse and 30 clinically stable RRMS patients (defined as no relapse within the last 12 months) as a control group. Olfactory threshold was impaired in patients with acute MS relapse at baseline (median difference = -3.5; inter-quartile range [IQR] -4.5- - 2.5; p < 0.001), week 4 (-2.5; IQR -3.0 - -2.0; p < 0.001), week 12 (-1.5; IQR -2.0 - -0.5; p = 0.002) and week 24 (-0.5; IQR -1.0 - 0.0; p = 0.159) compared to stable MS patients. Of note, in relapsing patients in whom disease-modifying treatment was initiated or escalated after relapse, threshold did not differ anymore from stable patients at week 12 (-0.5; IQR -1.0 - 0.5; p = 0.247) and week 24 (0.0; IQR -1.0 - 1.0; p = 0.753). Olfactory threshold impairment seems to be a transient bystander feature of MS relapse. It may be correlated to the level of inflammation within the CNS and might be a useful biomarker in this regard. Copyright © 2018 Elsevier B.V. All rights reserved.

Multiple products monitoring as a robust approach for peptide quantification.

PubMed

Baek, Je-Hyun; Kim, Hokeun; Shin, Byunghee; Yu, Myeong-Hee

2009-07-01

Quantification of target peptides and proteins is crucial for biomarker discovery. Approaches such as selected reaction monitoring (SRM) and multiple reaction monitoring (MRM) rely on liquid chromatography and mass spectrometric analysis of defined peptide product ions. These methods are not very widespread because the determination of quantifiable product ion using either SRM or MRM is a very time-consuming process. We developed a novel approach for quantifying target peptides without such an arduous process of ion selection. This method is based on monitoring multiple product ions (multiple products monitoring: MpM) from full-range MS2 spectra of a target precursor. The MpM method uses a scoring system that considers both the absolute intensities of product ions and the similarities between the query MS2 spectrum and the reference MS2 spectrum of the target peptide. Compared with conventional approaches, MpM greatly improves sensitivity and selectivity of peptide quantification using an ion-trap mass spectrometer.

Interactions between Impacting Particles and Target in Two-Phase Flow

NASA Astrophysics Data System (ADS)

Kang, Sang-Wook; Chow, Tze-Show

1996-11-01

The time-dependent interaction phenomena between a target and the incident solid particles borne by supersonic gas-jet stream have been numerically analyzed. In particular, the analysis dealt with particles such as aluminum, copper, and uranium ipinging on aluminum, copper, or uranium targets at various impact velocities ranging from 200 m/s to 1,000 m/s. Typical particle sizes were 50 to 100 micrometers. Results show considerable deformation of both the incident particles and the target when the velocity is greater than 500 m/s. Experiments performed on copper particles impacting an aluminum target demonstrate that under certain conditions (such as a supersonic gas jet issuing from a nozzle carrying solid particles) the impacts not only deform but also cause deposition of the particles on the surface. The present analysis shows the plausibility of such behavior when the particles impact the target at high velocities.

The use of silica-coated magnetic graphene microspheres as the adsorbent for the extraction of pyrethroid pesticides from orange and lettuce samples followed by GC-MS analysis.

PubMed

Hou, Mengying; Zang, Xiaohuan; Wang, Chun; Wang, Zhi

2013-10-01

Graphene-grafted ferroferric oxide microspheres were used as the adsorbent to extract some pyrethroid pesticides (bifenthrin, λ-cyhalothrin, cyfluthrin, cypermethrin, fenvalerate, and deltamethrin) from orange and lettuce samples prior to their determination by GC-MS. The main variables that could affect the extraction, including the amount of the adsorbent, pH of the sample solution, extraction time, concentration of salt, and desorption conditions, were investigated and optimized. Under the optimized conditions, a linear response was obtained in the concentration range of 0.3-100.0 ng/g for the analytes with the coefficients of determination ranging from 0.9877 to 0.9925. The LODs for the pyrethroids ranged from 0.01 to 0.02 ng/g. The method provided a good repeatability with RSDs < 10.6%. The recoveries for the six pyrethroid pesticides were in the range from 90.0 to 103.7%. The method was applied to the determination of the pesticides in orange and lettuce samples with a satisfactory result. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A dilute-and-shoot flow-injection tandem mass spectrometry method for quantification of phenobarbital in urine.

PubMed

Alagandula, Ravali; Zhou, Xiang; Guo, Baochuan

2017-01-15

Liquid chromatography/tandem mass spectrometry (LC/MS/MS) is the gold standard of urine drug testing. However, current LC-based methods are time consuming, limiting the throughput of MS-based testing and increasing the cost. This is particularly problematic for quantification of drugs such as phenobarbital, which is often analyzed in a separate run because they must be negatively ionized. This study examined the feasibility of using a dilute-and-shoot flow-injection method without LC separation to quantify drugs with phenobarbital as a model system. Briefly, a urine sample containing phenobarbital was first diluted by 10 times, followed by flow injection of the diluted sample to mass spectrometer. Quantification and detection of phenobarbital were achieved by an electrospray negative ionization MS/MS system operated in the multiple reaction monitoring (MRM) mode with the stable-isotope-labeled drug as internal standard. The dilute-and-shoot flow-injection method developed was linear with a dynamic range of 50-2000 ng/mL of phenobarbital and correlation coefficient > 0.9996. The coefficients of variation and relative errors for intra- and inter-assays at four quality control (QC) levels (50, 125, 445 and 1600 ng/mL) were 3.0% and 5.0%, respectively. The total run time to quantify one sample was 2 min, and the sensitivity and specificity of the method did not deteriorate even after 1200 consecutive injections. Our method can accurately and robustly quantify phenobarbital in urine without LC separation. Because of its 2 min run time, the method can process 720 samples per day. This feasibility study shows that the dilute-and-shoot flow-injection method can be a general way for fast analysis of drugs in urine. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Multicomponent T2 relaxation studies of the avian egg.

PubMed

Mitsouras, Dimitris; Mulkern, Robert V; Maier, Stephan E

2016-05-01

To investigate the tissue-like multiexponential T2 signal decays in avian eggs. Transverse relaxation studies of raw, soft-boiled and hard-boiled eggs were performed at 3 Tesla using a three-dimensional Carr-Purcell-Meiboom-Gill imaging sequence. Signal decays over a TE range of 11 to 354 ms were fitted assuming single- and multicomponent signal decays with up to three separately decaying components. Fat saturation was used to facilitate spectral assignment of observed decay components. Egg white, yolk and the centrally located latebra all demonstrate nonmonoexponential T2 decays. Specifically, egg white exhibits two-component decays with intermediate and long T2 times. Meanwhile, yolk and latebra are generally best characterized with triexponential decays, with short, intermediate and very long T2 decay times. Fat saturation revealed that the intermediate component of yolk could be attributed to lipids. Cooking of the egg profoundly altered the decay curves. Avian egg T2 decay curves cover a wide range of decay times. Observed T2 components in yolk and latebra as short as 10 ms, may prove valuable for testing clinical sequences designed to measure short T2 components, such as myelin-associated water in the brain. Thus we propose that the egg can be a versatile and widely available MR transverse relaxation phantom. © 2015 Wiley Periodicals, Inc.

Lipase catalyzed ultrasonic synthesis of poly-4-hydroxybutyrate-co-6-hydroxyhexanoate.

PubMed

Gumel, A M; Annuar, M S M; Chisti, Y

2013-05-01

Four different lipases were compared for ultrasound-mediated synthesis of the biodegradable copolymer poly-4-hydroxybutyrate-co-6-hydroxyhexanoate. The copolymerization was carried out in chloroform. Of the enzymes tested, Novozym 435 exhibited the highest copolymerization rate, in fact the reaction rate was observed to increase with about 26-fold from 30 to 50°C (7.9×10(-3)Ms(-1)), sonic power intensity of 2.6×10(3)Wm(-2) and dissipated energy of 130.4Jml(-1). Copolymerization rates with the Candida antarctica lipase A, Candida rugosa lipase, and Lecitase Ultra™ were lower at 2.4×10(-4), 1.3×10(-4) and 3.5×10(-4)Ms(-1), respectively. The catalytic efficiency depended on the enzyme. The efficiency ranged from 4.15×10(-3)s(-1)M(-1) for Novozym 435-1.48×10(-3)s(-1)M(-1) for C. rugosa lipase. Depending on the enzyme and sonication intensity, the monomer conversion ranged from 8.2% to 48.5%. The sonication power, time and temperature were found to affect the rate of copolymerization. Increasing sonication power intensity from 1.9×10(3) to 4.5×10(3)Wm(-2) resulted in an increased in acoustic pressure (P(a)) from 3.7×10(8) to 5.7×10(8)Nm(-2) almost 2.4-3.7 times greater than the acoustic pressure (1.5×10(8)Nm(-2)) that is required to cause cavitation in water. A corresponding acoustic particle acceleration (a) of 9.6×10(3)-1.5×10(4)ms(-2) was calculated i.e. approximately 984-1500 times greater than under the action of gravity. Copyright © 2012 Elsevier B.V. All rights reserved.

A new calibrant for MALDI-TOF-TOF-PSD-MS/MS of non-digested proteins for top-down proteomic analysis

USDA-ARS?s Scientific Manuscript database

RATIONALE: Matrix-assisted laser desorption/ionization (MALDI) time-of-flight-time-of-flight (TOF-TOF) tandem mass spectrometry (MS/MS) has seen increasing use for post-source decay (PSD)-MS/MS analysis of non-digested protein ions for top-down proteomic identification. However, there is no commonl...

Over 4,100 protein identifications from a Xenopus laevis fertilized egg digest using reversed-phase chromatographic prefractionation followed by capillary zone electrophoresis - electrospray ionization - tandem mass spectrometry analysis

PubMed Central

Yan, Xiaojing; Sun, Liangliang; Zhu, Guijie; Cox, Olivia F.; Dovichi, Norman J.

2016-01-01

A tryptic digest generated from Xenopus laevis fertilized embryos was fractionated by reversed phase liquid chromatography. One set of 30 fractions was analyzed by 100-min CZE-ESI-MS/MS separations (50 hr total instrument time), and a second set of 15 fractions was analyzed by 3-hr UPLC-ESI-MS/MS separations (45 hr total instrument time). CZE-MS/MS produced 70% as many protein IDs (4,134 vs. 5,787) and 60% as many peptide IDs (22,535 vs. 36,848) as UPLC-MS/MS with similar instrument time (50 h vs. 45 h) but with 50 times smaller total consumed sample amount (1.5 μg vs. 75 μg). Surprisingly, CZE generated peaks that were 25% more intense than UPLC for peptides that were identified by both techniques, despite the 50-fold lower loading amount; this high sensitivity reflects the efficient ionization produced by the electrokinetically-pumped nanospray interface used in CZE. This report is the first comparison of CZE-MS/MS and UPLC-MS/MS for large-scale eukaryotic proteomic analysis. The numbers of protein and peptide identifications produced by CZE-ESI-MS/MS approach those produced by UPLC-MS/MS, but with nearly two orders of magnitude lower sample amounts. PMID:27723263

Mass spectrometric measurements of driver gas arrival in the T4 free-piston shock-tunnel

NASA Astrophysics Data System (ADS)

Boyce, R. R.; Takahashi, M.; Stalker, R. J.

2005-12-01

Available test time is an important issue for ground-based flow research, particularly for impulse facilities such as shock tunnels, where test times of the order of several ms are typical. The early contamination of the test flow by the driver gas in such tunnels restricts the test time. This paper reports measurements of the driver gas arrival time in the test section of the T4 free-piston shock-tunnel over the total enthalpy range 3 17 MJ/kg, using a time-of-flight mass spectrometer. The results confirm measurements made by previous investigators using a choked duct driver gas detector at these conditions, and extend the range of previous mass spectrometer measurements to that of 3 20 MJ/kg. Comparisons of the contamination behaviour of various piston-driven reflected shock tunnels are also made.

Quantitative analysis of the immunosuppressant CP-690,550 in whole blood by column-switching high-performance liquid chromatography and mass spectrometry detection.

PubMed

Paniagua, Ricardo; Campbell, Andrew; Changelian, Paul S; Reitz, Bruce A; Prakash, Chandra; Borie, Dominic C

2005-10-01

A fast and accurate method to quantify the new immunosuppressive JAK3 inhibitor CP-690,550 in whole blood using a dual-pump liquid chromatography-liquid chromatography-mass spectrometry (LC/LC-MS) system was developed and validated in nonhuman primate blood. Before injection, blood samples were prepared by precipitation with a reagent that included methanol and acetonitrile (30:70, vol/vol) along with the internal standard (CP-istd). Column-switching LC/LC-MS analysis used online extraction followed by separation on a C8 analytic column and MS detection of the [M + H] CP-690,550 (m/z = 313.1) and CP internal standard (m/z = 288.1). Linearity was always better than r = 0.99 (n = 7) for CP-690,550 (range 2.5-750 ng/mL), with a lower limit of quantification (LLOQ) of 2.5 ng/mL. The intrarun accuracy and precision ranged from 103.0% to 105.4% and 2.7% to 4.3%, respectively (n = 5), and the interday precision ranged from 8.7% to 11.1%, and the interday accuracy ranged from 98.1% to 103.8% of nominal values (n = 14). The injection repeatability for the method was 1.3% (n = 7). Except for the LLOQ, the intraday accuracy and precision in human blood were also within 15% (n = 5). The combination of simple sample preparation and short analytic run time of this sensitive procedure makes it effective for monitoring the concentration of CP-690,550 in whole blood in organ-transplant recipients.

Validated method for determination of eight banned nitroimidazole residues in natural casings by LC/MS/MS with solid-phase extraction.

PubMed

Sun, Hanwen; Wang, Fengchi; Ai, Lianfeng; Guo, Chunhai; Chen, Ruichun

2009-01-01

A sensitive method based on solid-phase extraction-liquid chromatography-tandem mass spectrometry interfaced with electrospray ionization (SPE-LC-MS/MS-ESI) was developed for the simultaneous determination of 8 banned nitroimidazole (NOZ) drugs including metronidazole (MNZ), ronidazole (RNZ), dimetridazole (DMZ), tinidazole, ornidazole, secnidazole, metronidazole-OH (MNZOH, the metabolite of MNZ), and 2-hydroxymethyl-1-methyl-5-nitroimidazole (HMMNI, the metabolite of RNZ and DMZ) in natural casings. After extraction with ethyl acetate and evaporation, the NOZs were reconstituted in ethyl acetate and purified on a strong cation-exchange SPE column, and then LC/MS/MS analysis was performed by positive ESI applying multiple reaction monitoring of 2 transition reactions for each compound. The method was validated according to the European Union requirements (Commission Decision 2002/657/EC). Specificity, linearity, decision limit (CCalpha), detection capability (CCbeta), accuracy, and precision were determined. Average recoveries of the 8 NOZs from natural animal casing fortified at 3 levels (0.1, 0.5, and 1 microg/kg) ranged from 87.3 to 116.5%. The calculated CCalpha for NOZs ranged from 0.029 to 0.049 microg/kg, and CCbeta ranged from 0.049 to 0.083 microg/kg. Repeatability was in the range of 3.35-10.1%, and within-laboratory reproducibility was <10.3%.

Compositional Signatures of Conventional, Free Range, and Organic Pork Meat Using Fingerprint Techniques.

PubMed

Oliveira, Gislene B; Alewijn, Martin; Boerrigter-Eenling, Rita; van Ruth, Saskia M

2015-08-25

Consumers' interest in the way meat is produced is increasing in Europe. The resulting free range and organic meat products retail at a higher price, but are difficult to differentiate from their counterparts. To ascertain authenticity and prevent fraud, relevant markers need to be identified and new analytical methodology developed. The objective of this pilot study was to characterize pork belly meats of different animal welfare classes by their fatty acid (Fatty Acid Methyl Ester-FAME), non-volatile compound (electrospray ionization-tandem mass spectrometry-ESI-MS/MS), and volatile compound (proton-transfer-reaction mass spectrometry-PTR-MS) fingerprints. Well-defined pork belly meat samples (13 conventional, 15 free range, and 13 organic) originating from the Netherlands were subjected to analysis. Fingerprints appeared to be specific for the three categories, and resulted in 100%, 95.3%, and 95.3% correct identity predictions of training set samples for FAME, ESI-MS/MS, and PTR-MS respectively and slightly lower scores for the validation set. Organic meat was also well discriminated from the other two categories with 100% success rates for the training set for all three analytical approaches. Ten out of 25 FAs showed significant differences in abundance between organic meat and the other categories, free range meat differed significantly for 6 out of the 25 FAs. Overall, FAME fingerprinting presented highest discrimination power.

Compositional Signatures of Conventional, Free Range, and Organic Pork Meat Using Fingerprint Techniques

PubMed Central

Oliveira, Gislene B.; Alewijn, Martin; Boerrigter-Eenling, Rita; van Ruth, Saskia M.

2015-01-01

Consumers’ interest in the way meat is produced is increasing in Europe. The resulting free range and organic meat products retail at a higher price, but are difficult to differentiate from their counterparts. To ascertain authenticity and prevent fraud, relevant markers need to be identified and new analytical methodology developed. The objective of this pilot study was to characterize pork belly meats of different animal welfare classes by their fatty acid (Fatty Acid Methyl Ester—FAME), non-volatile compound (electrospray ionization-tandem mass spectrometry—ESI-MS/MS), and volatile compound (proton-transfer-reaction mass spectrometry—PTR-MS) fingerprints. Well-defined pork belly meat samples (13 conventional, 15 free range, and 13 organic) originating from the Netherlands were subjected to analysis. Fingerprints appeared to be specific for the three categories, and resulted in 100%, 95.3%, and 95.3% correct identity predictions of training set samples for FAME, ESI-MS/MS, and PTR-MS respectively and slightly lower scores for the validation set. Organic meat was also well discriminated from the other two categories with 100% success rates for the training set for all three analytical approaches. Ten out of 25 FAs showed significant differences in abundance between organic meat and the other categories, free range meat differed significantly for 6 out of the 25 FAs. Overall, FAME fingerprinting presented highest discrimination power. PMID:28231211

[Estimation of the atrioventricular time interval by pulse Doppler in the normal fetal heart].

PubMed

Hamela-Olkowska, Anita; Dangel, Joanna

2009-08-01

To assess normative values of the fetal atrioventricular (AV) time interval by pulse-wave Doppler methods on 5-chamber view. Fetal echocardiography exams were performed using Acuson Sequoia 512 in 140 singleton fetuses at 18 to 40 weeks of gestation with sinus rhythm and normal cardiac and extracardiac anatomy. Pulsed Doppler derived AV intervals were measured from left ventricular inflow/outflow view using transabdominal convex 3.5-6 MHz probe. The values of AV time interval ranged from 100 to 150 ms (mean 123 +/- 11.2). The AV interval was negatively correlated with the heart rhythm (p<0.001). Fetal heart rate decreased as gestation progressed (p<0.001). Thus, the AV intervals increased with the age of gestation (p=0.007). However, in the same subgroup of the fetal heart rate there was no relation between AV intervals and gestational age. Therefore, the AV intervals showed only the heart rate dependence. The 95th percentiles of AV intervals according to FHR ranged from 135 to 148 ms. 1. The AV interval duration was negatively correlated with the heart rhythm. 2. Measurement of AV time interval is easy to perform and has a good reproducibility. It may be used for the fetal heart block screening in anti-Ro and anti-La positive pregnancies. 3. Normative values established in the study may help obstetricians in assessing fetal abnormalities of the AV conduction.

Determination of residence times of ions in a resistive glass selected ion flow-drift tube using the Hadamard transformation.

PubMed

Spesyvyi, Anatolii; Španěl, Patrik

2015-09-15

Selected ion flow tube mass spectrometry, SIFT-MS, used for trace gas analyses has certain fundamental limitations that could be alleviated by adding a facility that allows reaction times and ion interaction energies to be varied. Thus, a selected ion flow-drift tube, SIFDT, has been created to explore the influence of an embedded electric field on these parameters and on reaction processes. The new SIFTD instrument was constructed using a miniature resistive glass drift tube. Arrival times of ions, t, analysed by a downstream quadrupole mass spectrometer over the m/z range 10-100 were studied by modulating the injected ion current using a gate lens. Single pulse modulation was compared with pseudorandom time multiplexing exploiting the Hadamard transformation. A simple model involving analysis of ethanol and water vapour mixture in air was used to explore the advantages of the SIFDT concept to SIFT-MS analysis. It is shown that the resistive glass drift tube is suitable for SIFDT experiments. The Hadamard transformation can be used to routinely determine reagent ion residence time in the flow-drift tube and also to observe differences in arrival times for different product ions. Two-dimensional data combining arrival time and mass spectra can be obtained rapidly. The calculated ion drift velocities vary with the reduced field strength, E/N, and the calculated ion mobilities agree with theoretical and previous literature values. This study has provided evidence that the SIFDT-MS technique can be implemented in a miniature and low-cost instrument and two- or three-dimensional data can be obtained (product ion count rates as functions of m/z, t and E/N) using the Hadamard transformation thus providing exciting possibilities for further analytical additions and extensions of the SIFT-MS technique. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

Time correlation between mononucleosis and initial symptoms of MS

PubMed Central

Endriz, John; Ho, Peggy P.

2017-01-01

Objective: To determine the average age of MS onset vs the age at which Epstein-Barr infection has previously occurred and stratify this analysis by sex and the blood level of Epstein-Barr nuclear antigen 1 (EBNA1) antibody. Methods: Using infectious mononucleosis (IM) as a temporal marker in data from the Swedish epidemiologic investigation of MS, 259 adult IM/MS cases were identified and then augmented to account for “missing” childhood data so that the average age of MS onset could be determined for cases binned by age of IM (as stratified by sex and EBNA1 titer level). Results: Mean age of IM vs mean age of MS reveals a positive time correlation for all IM ages (from ∼5 to ∼30 years), with IM-to-MS delay decreasing with increased age. When bifurcated by sex or EBNA1 blood titer levels, males and high-titer subpopulations show even stronger positive time correlation, while females and low-titer populations show negative time correlation in early childhood (long IM/MS delay). The correlation becomes positive in females beyond puberty. Conclusions: IM/MS time correlation implies causality if IM is time random. Alternative confounding models seem implausible, in light of constraints imposed by time-invariant delay observed here. Childhood infection with Epstein-Barr virus (EBV) in females and/or those genetically prone to low EBNA1 blood titers will develop MS slowly. Males and/or high EBNA1-prone develop MS more rapidly following IM infection at all ages. For all, postpubescent EBV infection is critical for the initiation and rapid development of MS. PMID:28271078

Two-dimensional color tissue Doppler imaging detects myocardial dysfunction before occurrence of hypertrophy in a young Maine Coon cat.

PubMed

Chetboul, Valerie; Sampedrano, Carolina Carlos; Gouni, Vassiliki; Nicolle, Audrey P; Pouchelon, Jean-Louis

2006-01-01

A 20-month-old healthy male Maine Coon cat was referred for a cardiovascular evaluation. Physical examination and electrocardiogram were normal. The end-diastolic subaortic interventricular septal thickness (6 mm; reference range: < or = 6mm) and the mitral flow late diastolic velocity (0.89 m/s; reference range: 0.2-0.8m/s) were within the upper ranges. However, M-mode echocardiography did not reveal any sign of hypertrophic cardiomyopathy (HCM). Tissue Doppler imaging (TDI) identified a marked left ventricular free wall dysfunction characterized by decreased myocardial velocities in early diastole, increased myocardial velocities in late diastole and the presence of postsystolic contractions both at the base and the apex for the longitudinal motion. One year later, the diagnosis of HCM was confirmed by conventional echocardiography and the cat died suddenly 2 months later. This report demonstrates for the first time in spontaneous HCM the sensitivity of TDI for early diagnosis of myocardial dysfunction and suggests that TDI should form part of the screening techniques for early diagnosis of feline HCM.

Ultrafast Screening and Quantitation of Pesticides in Food and Environmental Matrices by Solid-Phase Microextraction-Transmission Mode (SPME-TM) and Direct Analysis in Real Time (DART).

PubMed

Gómez-Ríos, Germán Augusto; Gionfriddo, Emanuela; Poole, Justen; Pawliszyn, Janusz

2017-07-05

The direct interface of microextraction technologies to mass spectrometry (MS) has unquestionably revolutionized the speed and efficacy at which complex matrices are analyzed. Solid Phase Micro Extraction-Transmission Mode (SPME-TM) is a technology conceived as an effective synergy between sample preparation and ambient ionization. Succinctly, the device consists of a mesh coated with polymeric particles that extracts analytes of interest present in a given sample matrix. This coated mesh acts as a transmission-mode substrate for Direct Analysis in Real Time (DART), allowing for rapid and efficient thermal desorption/ionization of analytes previously concentrated on the coating, and dramatically lowering the limits of detection attained by sole DART analysis. In this study, we present SPME-TM as a novel tool for the ultrafast enrichment of pesticides present in food and environmental matrices and their quantitative determination by MS via DART ionization. Limits of quantitation in the subnanogram per milliliter range can be attained, while total analysis time does not exceed 2 min per sample. In addition to target information obtained via tandem MS, retrospective studies of the same sample via high-resolution mass spectrometry (HRMS) were accomplished by thermally desorbing a different segment of the microextraction device.

Studies on the influence on flexural wall deformations on the development of the flow boundary layer

NASA Technical Reports Server (NTRS)

Schilz, W.

1978-01-01

Flexural wave-like deformations can be used to excite boundary layer waves which in turn lead to the onset of turbulence in the boundary layer. The investigations were performed with flow velocities between 5 m/s and 40 m/s. With four different flexural wave transmissions a frequency range from 0.2 kc/s to 1.5 kc/s and a phase velocity range from 3.5 m/s to 12 m/s was covered. The excitation of boundary layer waves becomes most effective if the phase velocity of the flexural wave coincides with the phase velocity region of unstable boundary layer waves.

Fast Simultaneous Determination of 13 Nucleosides and Nucleobases in Cordyceps sinensis by UHPLC-ESI-MS/MS.

PubMed

Zong, Shi-Yu; Han, Han; Wang, Bing; Li, Ning; Dong, Tina Ting-Xia; Zhang, Tong; Tsim, Karl W K

2015-12-04

A reliable ultra-high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry (UHPLC-ESI-MS/MS) method for the fast simultaneous determination of 13 nucleosides and nucleobases in Cordyceps sinensis (C. sinensis) with 2-chloroadenosine as internal standard was developed and validated. Samples were ultrasonically extracted in an ice bath thrice, and the optimum analyte separation was performed on an ACQUITY UPLC(TM) HSS C18 column (100 mm × 2.1 mm, 1.8 μm) with gradient elution. All targeted analytes were separated in 5.5 min. Furthermore, all calibration curves showed good linear regression (r > 0.9970) within the test ranges, and the limits of quantitation and detection of the 13 analytes were less than 150 and 75 ng/mL, respectively. The relative standard deviations (RSDs) of intra- and inter-day precisions were <6.23%. Recoveries of the quantified analytes ranged within 85.3%-117.3%, with RSD < 6.18%. The developed UHPLC-ESI-MS/MS method was successfully applied to determine nucleosides and nucleobases in 11 batches of C. sinensis samples from different regions in China. The range for the total content in the analyzed samples was 1329-2057 µg/g.

Anticipation of direction and time of perturbation modulates the onset latency of trunk muscle responses during sitting perturbations.

PubMed

Milosevic, Matija; Shinya, Masahiro; Masani, Kei; Patel, Kramay; McConville, Kristiina M V; Nakazawa, Kimitaka; Popovic, Milos R

2016-02-01

Trunk muscles are responsible for maintaining trunk stability during sitting. However, the effects of anticipation of perturbation on trunk muscle responses are not well understood. The objectives of this study were to identify the responses of trunk muscles to sudden support surface translations and quantify the effects of anticipation of direction and time of perturbation on the trunk neuromuscular responses. Twelve able-bodied individuals participated in the study. Participants were seated on a kneeling chair and support surface translations were applied in the forward and backward directions with and without direction and time of perturbation cues. The trunk started moving on average approximately 40ms after the perturbation. During unanticipated perturbations, average latencies of the trunk muscle contractions were in the range between 103.4 and 117.4ms. When participants anticipated the perturbations, trunk muscle latencies were reduced by 16.8±10.0ms and the time it took the trunk to reach maximum velocity was also reduced, suggesting a biomechanical advantage caused by faster muscle responses. These results suggested that trunk muscles have medium latency responses and use reflexive mechanisms. Moreover, anticipation of perturbation decreased trunk muscles latencies, suggesting that the central nervous system modulated readiness of the trunk based on anticipatory information. Copyright © 2015 Elsevier Ltd. All rights reserved.

Amygdala Damage Affects Event-Related Potentials for Fearful Faces at Specific Time Windows

PubMed Central

Rotshtein, Pia; Richardson, Mark P; Winston, Joel S; Kiebel, Stefan J; Vuilleumier, Patrik; Eimer, Martin; Driver, Jon; Dolan, Raymond J

2010-01-01

The amygdala is known to influence processing of threat-related stimuli in distant brain regions, including visual cortex. The time-course of these distant influences is unknown, although this information is important for resolving debates over likely pathways mediating an apparent rapidity in emotional processing. To address this, we recorded event-related potentials (ERPs) to seen fearful face expressions, in preoperative patients with medial temporal lobe epilepsy who had varying degrees of amygdala pathology, plus healthy volunteers. We found that amygdala damage diminished ERPs for fearful versus neutral faces within the P1 time-range, ∼100–150 ms, and for a later component at ∼500–600 ms. Individual severity of amygdala damage determined the magnitude of both these effects, consistent with a causal amygdala role. By contrast, amygdala damage did not affect explicit perception of fearful expressions nor a distinct emotional ERP effect at 150–250 ms. These results demonstrate two distinct time-points at which the amygdala influences fear processing. The data also demonstrate that while not all aspects of expression processing are disrupted by amygdala damage, there is a crucial impact on an early P1 component. These findings are consistent with the existence of multiple processing stages or routes for fearful faces that vary in their dependence on amygdala function. Hum Brain Mapp, 2010. © 2009 Wiley-Liss, Inc. PMID:20017134

Event-related brain potential correlates of two states of conscious awareness in memory

PubMed Central

Düzel, Emrah; Yonelinas, Andrew P.; Mangun, George R.; Heinze, Hans-Jochen; Tulving, Endel

1997-01-01

We report an event-related potential (ERP) experiment of human recognition memory that explored the relation between conscious awareness and electrophysiological activity of the brain. We recorded ERPs from healthy adults while they made “remember” and “know” recognition judgments about previously seen words. These two kinds of judgments reflect “autonoetic” and “noetic” awareness, respectively. The ERP effects differed between the two kinds of awareness while they were similar for “true” and “false” recognition. Noetic awareness was associated with a temporoparietal positivity in the N400 range (325–600 ms) and a late (600–1,000 ms) frontocentral negativity, whereas autonoetic awareness was associated with a widespread, late, bifrontal and left parietotemporal (600–1000 ms) positivity. In the very late (1,300–1,900 ms) time window, a right frontal positivity was observed for both remember and know judgments of both true and false targets. These results provide physiological evidence for two types of conscious awareness in episodic memory retrieval. PMID:9159185

Determination of itopride in human plasma by liquid chromatography coupled to tandem mass spectrometric detection: application to a bioequivalence study.

PubMed

Lee, Heon-Woo; Seo, Ji-Hyung; Choi, Seung-Ki; Lee, Kyung-Tae

2007-01-30

A simple method using a one-step liquid-liquid extraction (LLE) with butyl acetate followed by high-performance liquid chromatography (HPLC) with positive ion electrospray ionization tandem mass spectrometric (ESI-MS/MS) detection was developed for the determination of itopride in human plasma, using sulpiride as an internal standard (IS). Acquisition was performed in multiple reaction monitoring (MRM) mode, by monitoring the transitions: m/z 359.5>166.1 for itopride and m/z 342.3>111.6 for IS, respectively. Analytes were chromatographed on an YMC C18 reverse-phase chromatographic column by isocratic elution with 1 mM ammonium acetate buffer-methanol (20: 80, v/v; pH 4.0 adjusted with acetic acid). Results were linear (r2=0.9999) over the studied range (0.5-1000 ng mL(-1)) with a total analysis time per run of 2 min for LC-MS/MS. The developed method was validated and successfully applied to bioequivalence studies of itopride hydrochloride in healthy male volunteers.

Ultra-performance liquid chromatography tandem mass spectrometry for simultaneous determination of natural steroid hormones in sea lamprey (Petromyzon marinus) plasma and tissues.

PubMed

Wang, Huiyong; Bussy, Ugo; Chung-Davidson, Yu-Wen; Li, Weiming

2016-01-15

This study aims to provide a rapid, sensitive and precise UPLC-MS/MS method for target steroid quantitation in biological matrices. We developed and validated an UPLC-MS/MS method to simultaneously determine 16 steroids in plasma and tissue samples. Ionization sources of Electrospray Ionization (ESI) and Atmospheric Pressure Chemical Ionization (APCI) were compared in this study by testing their spectrometry performances at the same chromatographic conditions, and the ESI source was found up to five times more sensitive than the APCI. Different sample preparation techniques were investigated for an optimal extraction of steroids from the biological matrices. The developed method exhibited excellent linearity for all analytes with regression coefficients higher than 0.99 in broad concentration ranges. The limit of detection (LOD) was from 0.003 to 0.1ng/mL. The method was validated according to FDA guidance and applied to determine steroids in sea lamprey plasma and tissues (fat and testes) by the developed method. Copyright © 2015. Published by Elsevier B.V.

Positive and negative electrospray LC-MS-MS methods for quantitation of the antiparasitic endectocide drugs, abamectin, doramectin, emamectin, eprinomectin, ivermectin, moxidectin and selamectin in milk.

PubMed

Durden, David A

2007-05-01

Avermectin endectocides are used for the treatment of cattle against a variety of nematode and arthropod parasites, and consequently may appear in milk after normal or off-label use. The compounds abamectin, doramectin, and ivermectin, contain only C, H and O and may be expected to be detected by LC-MS in negative ion mode. The others contain nitrogen in addition and would be expected to be preferentially ionized in positive mode. The use of positive ion and negative ion methods with electrospray LC-MS-MS were compared. Using negative ion the compounds abamectin, doramectin, ivermectin, emamectin, eprinomectin, and moxidectin gave a curvilinear response and were quantified in raw milk by LC-MS-MS with a triethylamine-acetonitrile buffer over the concentration range 1-60 ppb (microg/kg) using selamectin as the internal standard. The limits of detection (LOD) were between 0.19 ppb (doramectin) and 0.38 ppb (emamectin). The compounds gave maximum sensitivity with positive ionisation from a formic acid-ammonium formate-acetonitrile buffer and were detected in milk (LC-MS-MS) also with a curvilinear response over the range 0.5-60 ppb. Although the positive ion signals were larger, with somewhat lower limits of detection (LOD between 0.06 ppb (doramectin) and 0.32 ppb (moxidectin) the negative ion procedure gave a more linear response and more consistent results. Comparison of spiked samples in the range 2-50 ppb showed a high degree of correlation between the two methods.

An HPLC-MS method for the quantification of new acetylcholinesterase inhibitor PC 48 (7-MEOTA-donepezil like compound) in rat plasma: Application to a pharmacokinetic study.

PubMed

Mzik, Martin; Korabecny, Jan; Nepovimova, Eugenie; Voříšek, Viktor; Palička, Vladimir; Kuca, Kamil; Zdarova Karasova, Jana

2016-05-01

A simple, rapid and sensitive method based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been developed and validated for the quantitative determination in rat plasma of a new candidate for AD treatment, namely PC 48 (a 7-MEOTA-donepezil like compound) in rat plasma. Sample preparation involved pH adjustment with sodium hydroxide followed by solvent extraction with ethyl acetate:dichloromethane (80:20, v/v). The chromatographic separation was achieved on an Ascentis Express RP-Amide column (75 mm × 2.1mm, 2.7 μm) with a gradient mobile phase consisting of 0.05 M aqueous formic acid and acetonitrile. Detection was carried out using positive-ion electrospray tandem mass spectrometry on an LTQ XL system using the MS/MS CID (collision-induced dissociation) mode. The method was linear in the range 0.1-1000 ng/ml (r(2)=0.999) with a lower limit of quantitation of 0.1 ng/mL. Extraction recovery was in the range 63.5-72.1% for PC 48 and 70.5% for reserpine (internal standard, IS). Intra- and inter-day precisions measured as relative standard deviation were below 10.8% and accuracy was from -7.2% to 7.4%. The method was successfully applied to a pharmacokinetic study involving intramuscular application of 3.86 mg/kg PC 48 to rats for the first time. Pharmacokinetic parameters for PC 48 include Cmax 39.09 ± 4.45 ng/mL,Tmax 5.00 ± 3.08 min, AUC0-t 23374 ± 4045 min ng/mL and t1/2 1065 ± 246 min. Copyright © 2016 Elsevier B.V. All rights reserved.

The quantitative surface analysis of an antioxidant additive in a lubricant oil matrix by desorption electrospray ionization mass spectrometry

PubMed Central

Da Costa, Caitlyn; Reynolds, James C; Whitmarsh, Samuel; Lynch, Tom; Creaser, Colin S

2013-01-01

RATIONALE Chemical additives are incorporated into commercial lubricant oils to modify the physical and chemical properties of the lubricant. The quantitative analysis of additives in oil-based lubricants deposited on a surface without extraction of the sample from the surface presents a challenge. The potential of desorption electrospray ionization mass spectrometry (DESI-MS) for the quantitative surface analysis of an oil additive in a complex oil lubricant matrix without sample extraction has been evaluated. METHODS The quantitative surface analysis of the antioxidant additive octyl (4-hydroxy-3,5-di-tert-butylphenyl)propionate in an oil lubricant matrix was carried out by DESI-MS in the presence of 2-(pentyloxy)ethyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate as an internal standard. A quadrupole/time-of-flight mass spectrometer fitted with an in-house modified ion source enabling non-proximal DESI-MS was used for the analyses. RESULTS An eight-point calibration curve ranging from 1 to 80 µg/spot of octyl (4-hydroxy-3,5-di-tert-butylphenyl)propionate in an oil lubricant matrix and in the presence of the internal standard was used to determine the quantitative response of the DESI-MS method. The sensitivity and repeatability of the technique were assessed by conducting replicate analyses at each concentration. The limit of detection was determined to be 11 ng/mm2 additive on spot with relative standard deviations in the range 3–14%. CONCLUSIONS The application of DESI-MS to the direct, quantitative surface analysis of a commercial lubricant additive in a native oil lubricant matrix is demonstrated. © 2013 The Authors. Rapid Communications in Mass Spectrometry published by John Wiley & Sons, Ltd. PMID:24097398

Optimization of mass spectrometric parameters improve the identification performance of capillary zone electrophoresis for single-shot bottom-up proteomics analysis.

PubMed

Zhang, Zhenbin; Dovichi, Norman J

2018-02-25

The effects of MS1 injection time, MS2 injection time, dynamic exclusion time, intensity threshold, and isolation width were investigated on the numbers of peptide and protein identifications for single-shot bottom-up proteomics analysis using CZE-MS/MS analysis of a Xenopus laevis tryptic digest. An electrokinetically pumped nanospray interface was used to couple a linear-polyacrylamide coated capillary to a Q Exactive HF mass spectrometer. A sensitive method that used a 1.4 Th isolation width, 60,000 MS2 resolution, 110 ms MS2 injection time, and a top 7 fragmentation produced the largest number of identifications when the CZE loading amount was less than 100 ng. A programmable autogain control method (pAGC) that used a 1.4 Th isolation width, 15,000 MS2 resolution, 110 ms MS2 injection time, and top 10 fragmentation produced the largest number of identifications for CZE loading amounts greater than 100 ng; 7218 unique peptides and 1653 protein groups were identified from 200 ng by using the pAGC method. The effect of mass spectrometer conditions on the performance of UPLC-MS/MS was also investigated. A fast method that used a 1.4 Th isolation width, 30,000 MS2 resolution, 45 ms MS2 injection time, and top 12 fragmentation produced the largest number of identifications for 200 ng UPLC loading amount (6025 unique peptides and 1501 protein groups). This is the first report where the identification number for CZE surpasses that of the UPLC at the 200 ng loading level. However, more peptides (11476) and protein groups (2378) were identified by using UPLC-MS/MS when the sample loading amount was increased to 2 μg with the fast method. To exploit the fast scan speed of the Q-Exactive HF mass spectrometer, higher sample loading amounts are required for single-shot bottom-up proteomics analysis using CZE-MS/MS. Copyright © 2017 Elsevier B.V. All rights reserved.

Simultaneous quantification of cholesterol sulfate, androgen sulfates, and progestagen sulfates in human serum by LC-MS/MS.

PubMed

Sánchez-Guijo, Alberto; Oji, Vinzenz; Hartmann, Michaela F; Traupe, Heiko; Wudy, Stefan A

2015-09-01

Steroids are primarily present in human fluids in their sulfated forms. Profiling of these compounds is important from both diagnostic and physiological points of view. Here, we present a novel method for the quantification of 11 intact steroid sulfates in human serum by LC-MS/MS. The compounds analyzed in our method, some of which are quantified for the first time in blood, include cholesterol sulfate, pregnenolone sulfate, 17-hydroxy-pregnenolone sulfate, 16-α-hydroxy-dehydroepiandrosterone sulfate, dehydroepiandrosterone sulfate, androstenediol sulfate, androsterone sulfate, epiandrosterone sulfate, testosterone sulfate, epitestosterone sulfate, and dihydrotestosterone sulfate. The assay was conceived to quantify sulfated steroids in a broad range of concentrations, requiring only 300 μl of serum. The method has been validated and its performance was studied at three quality controls, selected for each compound according to its physiological concentration. The assay showed good linearity (R(2) > 0.99) and recovery for all the compounds, with limits of quantification ranging between 1 and 80 ng/ml. Averaged intra-day and between-day precisions (coefficient of variation) and accuracies (relative errors) were below 10%. The method has been successfully applied to study the sulfated steroidome in diseases such as steroid sulfatase deficiency, proving its diagnostic value. This is, to our best knowledge, the most comprehensive method available for the quantification of sulfated steroids in human blood. Copyright © 2015 by the American Society for Biochemistry and Molecular Biology, Inc.

Low-molecular-weight color pI markers to monitor on-line the peptide focusing process in OFFGEL fractionation.

PubMed

Michelland, Sylvie; Bourgoin-Voillard, Sandrine; Cunin, Valérie; Tollance, Axel; Bertolino, Pascal; Slais, Karel; Seve, Michel

2017-08-01

High-throughput mass spectrometry-based proteomic analysis requires peptide fractionation to simplify complex biological samples and increase proteome coverage. OFFGEL fractionation technology became a common method to separate peptides or proteins using isoelectric focusing in an immobilized pH gradient. However, the OFFGEL focusing process may be further optimized and controlled in terms of separation time and pI resolution. Here we evaluated OFFGEL technology to separate peptides from different samples in the presence of low-molecular-weight (LMW) color pI markers to visualize the focusing process. LMW color pI markers covering a large pH range were added to the peptide mixture before OFFGEL fractionation using a 24-wells device encompassing the pH range 3-10. We also explored the impact of LMW color pI markers on peptide fractionation labeled previously for iTRAQ. Then, fractionated peptides were separated by RP_HPLC prior to MS analysis using MALDI-TOF/TOF mass spectrometry in MS and MS/MS modes. Here we report the performance of the peptide focusing process in the presence of LMW color pI markers as on-line trackers during the OFFGEL process and the possibility to use them as pI controls for peptide focusing. This method improves the workflow for peptide fractionation in a bottom-up proteomic approach with or without iTRAQ labeling. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Development and validation of a UPLC-MS/MS method for quantitation of droxidopa in human plasma: Application to a pharmacokinetic study.

PubMed

Wang, Haidong; Yang, Guangsheng; Zhou, Jinyu; Pei, Jiang; Zhang, Qiangfeng; Song, Xingfa; Sun, Zengxian

2016-08-01

In this study, a simple and sensitive ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed and validated for quantitation of droxidopa in human plasma for the first time. A simple plasma protein precipitation method using methanol containing 3% formic acid was selected, and the separation was achieved by an Acquity UPLC™ BEH Amide column (2.1mm×50mm, 1.7μm) with a gradient elution using acetonitrile, ammonium formate buffer and formic acid as mobile phase. The detection of droxidopa and benserazide (internal standard, IS) was performed using positive-ion electrospray tandem mass spectrometry via multiple reaction monitoring (MRM). The precursor-to-product ion transitions m/z 214.2→m/z 152.0 for droxidopa, and m/z 258.1→m/z 139.1 for IS were used for quantification. A lower limit of quantification of 5.00ng/mL was achieved and the linear curve range was 5.00-4000ng/mL using a weighted (1/x(2)) linear regression model. Intra-assay and inter-assay precision was less than 10.2%, and the accuracy ranged from 0.1% to 2.1%. Stability, recovery and matrix effects were within the acceptance criteria recommended by the regulatory bioanalytical guidelines. The method was successfully applied to a pharmacokinetic study of droxidopa in healthy Chinese volunteers. Copyright © 2016. Published by Elsevier B.V.

Determination of parthenolide in rat plasma by UPLC-MS/MS and its application to a pharmacokinetic study.

PubMed

Zhao, Ai-qin; Zhao, Ji-hong; Zhang, Shu-qing; Pan, Yong-yang; Huo, Xu-lei

2016-02-05

A rapid, sensitive and selective ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method was developed and validated for the determination and pharmacokinetic investigation of parthenolide in rat plasma. Sample preparation was accomplished through a simple one-step deproteinization procedure with 0.2mL of acetonitrile containing 30ng/mL of pirfenidone (IS), and to a 0.1mL plasma sample. Plasma samples were separated by UPLC on an Acquity UPLC BEH C18 column using a mobile phase consisting of acetonitrile-0.1% formic acid in water with gradient elution. The total run time was 3.0min and the elution of parthenolide was at 1.33min. The detection was performed on a triple quadrupole tandem mass spectrometer in the multiple reaction-monitoring (MRM) mode using the respective transitions m/z 249.2→231.1 for parthenolide and m/z 186.2→92.1 for pirfenidone (IS), respectively. The calibration curve was linear over the range of 2.0-500ng/mL with a lower limit of quantitation (LLOQ) of 2.0ng/mL. Mean recovery of parthenolide in plasma was in the range of 78.2-86.6%. Intra-day and inter-day precision were both <8.3%. This method was successfully applied in pharmacokinetic study after oral and intravenous administration of parthenolide in rats. Copyright © 2015 Elsevier B.V. All rights reserved.

A validated UPLC-MS/MS method coupled with protein precipitation and ion exchange solid phase extraction for the quantitation of porcine relaxin B29 in dog plasma and its application to a pharmacokinetic study.

PubMed

Su, Chong; Sun, Hui; Yang, Hong; Yin, Lei; Zhang, Jiwen; Fawcett, John Paul; Gu, Jingkai

2017-11-01

Porcine relaxin is a 6 kDa peptide hormone of pregnancy with important physiological and pharmacological effects. It contains a number of analogs of which porcine relaxin B29 is one of the most important. To support the development of porcine relaxin B29 as a new drug, we established an UPLC-MS/MS method for its quantitation in dog plasma. Sample preparation by protein precipitation and ion exchange solid phase extraction was followed by UPLC on an XBridge™ BEH300 C18 column at 40 °C in a run time of only 5.5 min. Detection was performed on a Qtrap 6500 mass spectrometer using ESI in the positive ion mode with MRM of the transitions at m/z 831.7 [M+7H] 7+  → 505.4 and m/z 1162.4 [M+5H] 5+  → 226 for pRLX B29 and internal standard (recombinant human insulin), respectively. The method was linear over the concentration range 30-2000 ng/mL with no matrix effects. Intra- and inter-day precisions were < 15% with accuracies in the range 98.8-100.6%. The method was successfully applied to a pharmacokinetic study in beagle dogs after administration of a 0.15 mg/kg intravenous dose. Graphical abstract Sample preparation and detection procedure.

Determination of thiopurine S-methyltransferase activity by hydrophilic interaction liquid chromatography hyphenated with mass spectrometry.

PubMed

Pecher, Daniel; Dokupilová, Svetlana; Zelinková, Zuzana; Peppelenbosch, Maikel; Mikušová, Veronika; Mikuš, Peter

2017-08-05

Thiopurine S-methyltransferase (TPMT) plays an important role in the metabolism of thiopurines used in the therapy of inflammatory bowel diseases (IBD). In this work a new progressive method for the determination of TPMT activity in red blood cells lysates was developed. Analysis was carried out by means of hydrophilic interaction liquid chromatography (HILIC) hyphenated with mass spectrometry (MS). In comparison with reversed-phase high-performance liquid chromatography (RP-HPLC), that has been typically applied in determination of TPMT activity, the HILIC significantly improved the analytical signal provided by MS, shortened analysis time, and improved chromatographic resolution. The HILIC-HPLC-MS method was optimized and validated, providing favorable parameters of detection and quantitation limits (5.5 and 16.5pmol/mL, respectively), linearity (coefficient of determination 0.9999 in the range of 0.01-1.0nmol/mL), recovery and precision (93.25-100.37% with RSD 1.06-1.32% in the whole concentration range of QC samples). Moreover, in contrast to the conventional RP-HPLC-UV approach, the complex phenotype TPMT profiles can be reliably and without interferences monitored using the HILIC-HPLC-MS method. Such advanced monitoring can provide valuable detail information on the thiopurines (e.g. evaluating ratio of methylated and non-methylated 6-mercaptopurine) and, by that, TPMT action in biological systems before and during the therapy of IBD. Copyright © 2017 Elsevier B.V. All rights reserved.

Determination of spinetoram and its metabolites in amaranth and parsley using QuEChERS-based extraction and liquid chromatography-tandem mass spectrometry.

PubMed

Park, Ki Hun; Choi, Jeong-Heui; Abd El-Aty, A M; Cho, Soon-Kil; Park, Jong-Hyouk; Kim, Bo Mi; Yang, Angel; Na, Tae Woong; Rahman, Musfiqur; Im, Geon-Jae; Shim, Jae-Han

2012-10-15

In this study, a simultaneous method was developed for the determination of spinetoram (XDE-175-J and XDE-175-L) and its demethyl metabolites (N-demethyl-175-J and N-demethyl-175-L) and formyl metabolites (N-formyl-175-J and N-formyl-175-L) in the minor crops; amaranth and parsley. The method uses quick, easy, cheap, effective, rugged, and safe (QuEChERS)-based extraction. Afterwards, the analytes were quantified and confirmed via liquid chromatography-electrospray ionisation tandem mass spectrometry (LC-ESI-MS/MS) in the positive ion mode using multiple reaction monitoring (MRM). Calibration curves were linear over the calibration ranges for all the analytes tested with r(2)>0.993. Limits of detection and quantitation were 0.01 and 0.03 mg/kg for all the tested analytes in amaranth and parsley, respectively. Recovery values, at spiking levels 0.05 and 0.25 mg/kg, ranged from 71.0% to 115.2% with relative standard deviations <15%, except for N-formyl-175-J in both amaranth and parsley. This method was applied to field-incurred samples and was shown to provide an adequate sensitivity and performance for the simultaneous determination of spinetoram and metabolites. To the best of our knowledge, this is the first time spinetoram and its metabolites were quantified using LC-MS/MS in minor crops. Copyright © 2012 Elsevier Ltd. All rights reserved.

Comprehensive two-dimensional gas chromatography using partial modulation via a pulsed flow valve with a short modulation period.

PubMed

Freye, Chris E; Bahaghighat, H Daniel; Synovec, Robert E

2018-01-15

Partial modulation via a pulsed flow valve for comprehensive two-dimensional (2D) gas chromatography (GC × GC) is demonstrated, producing narrow peak widths, 2 W b , on the secondary separation dimension, 2 D, coupled with short modulation periods, P M , thus producing a high peak capacity on the 2 D dimension, 2 n c . The GC × GC modulator is a pulse flow valve that injects a pulse of carrier gas at the specified P M , at the connection between the primary, 1 D, column and the 2 D column. Using a commercially available pulse flow valve, this injection technique performs a combination of vacancy chromatography and frontal analysis, whereby each pulse disturbance in the analyte concentration profile as it exits the 1 D column results in data that is readily converted into a 2 D separation. A three-step process converts the raw data into a format analogous to a GC × GC separation, incorporating signal differentiation, baseline correction and conversion to a GC × GC chromatogram representation. A 115-component test mixture with a wide range of boiling points (36-372°C) of nine compound classes is demonstrated using modulation periods of P M = 50, 100, 250, and 500ms, respectively. For the test mixture with a P M of 250ms, peak shapes on 2 D are symmetric with apparent 2 W b ranging from 12 to 45ms producing a 2 n c of ~ 10. Based on the average peak width of 0.93s on the 1 D separation for a time window of 400s, the 1 D peak capacity is 1 n c ∼ 430. Thus, the ideal 2D peak capacity n c,2D is 4300 or a peak capacity production of 650 peaks/min using the P M of 250ms. Additionally, for a P M of 50, 100 and 500ms, the 2 n c are 4, 7, and 12, respectively. Retention times on 2 D, 2 t R , are reproducible having standard deviations less than 1ms. Finally, the processed data is shown to be quantitative, with an average RSD of 4.7% for test analytes. Copyright © 2017 Elsevier B.V. All rights reserved.

An impulse-driven liquid-droplet deposition interface for combining LC with MALDI MS and MS/MS.

PubMed

Young, J Bryce; Li, Liang

2006-03-01

A simple and robust impulse-driven droplet deposition system was developed for off-line liquid chromatography matrix-assisted laser desorption ionization mass spectrometry (LC-MALDI MS). The system uses a solenoid operated with a pulsed voltage power supply to generate impulses that dislodge the hanging droplets from the LC outlet directly to a MALDI plate via a momentum transfer process. There is no contact between the LC outlet and the collection surface. The system is compatible with solvents of varying polarity and viscosity, and accommodates the use of hydrophobic and hydrophilic MALDI matrices. MALDI spots are produced on-line with the separation, and do not require further processing before MS analysis. It is shown that high quality MALDI spectra from 5 fmol of pyro-Glu-fibrinopeptide deposition after LC separation could be obtained using the device, indicating that there was no sample loss in the interface. To demonstrate the analytical performance of the system as a proteome analysis tool, a range of BSA digest concentrations covering about 3 orders of magnitude, from 5 fmol to 1 pmol, were analyzed by LC-MALDI quadrupole time-of-flight MS, yielding 6 and 57% amino acid sequence coverage, respectively. In addition, a complex protein mixture of an E. coli cell extract was tryptically digested and analyzed by LC-MALDI MS, resulting in the detection of a total of 409 unique peptides from 100 fractions of 15-s intervals.

Increasing Polyaromatic Hydrocarbon (PAH) Molecular Coverage during Fossil Oil Analysis by Combining Gas Chromatography and Atmospheric-Pressure Laser Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR MS)

PubMed Central

Benigni, Paolo; DeBord, J. Daniel; Thompson, Christopher J.; Gardinali, Piero; Fernandez-Lima, Francisco

2016-01-01

Thousands of chemically distinct compounds are encountered in fossil oil samples that require rapid screening and accurate identification. In the present paper, we show for the first time, the advantages of gas chromatography (GC) separation in combination with atmospheric-pressure laser ionization (APLI) and ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) for the screening of polyaromatic hydrocarbons (PAHs) in fossil oils. In particular, reference standards of organics in shale oil, petroleum crude oil, and heavy sweet crude oil were characterized by GC-APLI-FT-ICR MS and APLI-FT-ICR MS. Results showed that, while APLI increases the ionization efficiency of PAHs, when compared to other ionization sources, the complexity of the fossil oils reduces the probability of ionizing lower-concentration compounds during direct infusion. When gas chromatography precedes APLI-FT-ICR MS, an increase (more than 2-fold) in the ionization efficiency and an increase in the signal-to-noise ratio of lower-concentration fractions are observed, giving better molecular coverage in the m/z 100–450 range. That is, the use of GC prior to APLI-FT-ICR MS resulted in higher molecular coverage, higher sensitivity, and the ability to separate and characterize molecular isomers, while maintaining the ultrahigh resolution and mass accuracy of the FT-ICR MS separation. PMID:27212790

Evaluation of laser diode thermal desorption-tandem mass spectrometry (LDTD-MS-MS) in forensic toxicology.

PubMed

Bynum, Nichole D; Moore, Katherine N; Grabenauer, Megan

2014-10-01

Many forensic laboratories experience backlogs due to increased drug-related cases. Laser diode thermal desorption (LDTD) has demonstrated its applicability in other scientific areas by providing data comparable with instrumentation, such as liquid chromatography-tandem mass spectrometry, in less time. LDTD-MS-MS was used to validate 48 compounds in drug-free human urine and blood for screening or quantitative analysis. Carryover, interference, limit of detection, limit of quantitation, matrix effect, linearity, precision and accuracy and stability were evaluated. Quantitative analysis indicated that LDTD-MS-MS produced precise and accurate results with the average overall within-run precision in urine and blood represented by a %CV <14.0 and <7.0, respectively. The accuracy for all drugs in urine ranged from 88.9 to 104.5% and 91.9 to 107.1% in blood. Overall, LDTD has the potential for use in forensic toxicology but before it can be successfully implemented that there are some challenges that must be addressed. Although the advantages of the LDTD system include minimal maintenance and rapid analysis (∼10 s per sample) which makes it ideal for high-throughput forensic laboratories, a major disadvantage is its inability or difficulty analyzing isomers and isobars due to the lack of chromatography without the use of high-resolution MS; therefore, it would be best implemented as a screening technique. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Analysis of non-steroidal anti-inflammatory drugs in milk using QuEChERS and liquid chromatography coupled to mass spectrometry: triple quadrupole versus Q-Orbitrap mass analyzers.

PubMed

Rúbies, Antoni; Guo, Lili; Centrich, Francesc; Granados, Mercè

2016-08-01

We developed a Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) method for the high throughput determination of 10 non-steroidal anti-inflammatory drugs (NSAIDs) in milk samples using high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) with a triple quadrupole (QqQ) instrument and an electrospray ionization (ESI) source. The new extraction procedure is highly efficient, and we obtained absolute recoveries in the range 78.1-97.1 % for the extraction and clean-up steps. Chromatographic separation is performed in the gradient mode with a biphenyl column and acidic mobile phases consisting of water and acetonitrile containing formic acid. The chromatographic run time was about 12 min, and NSAID peaks showed a good symmetry factor. For MS/MS detection, we used multiple reaction monitoring (MRM) mode, using ESI in both positive and negative modes. Our method has been validated in compliance with the European Commission Decision 657/2002/EC, and we obtained very satisfactory results in inter-laboratory testing. Furthermore, we explored the use of a hybrid high resolution mass spectrometer, combining a quadrupole and an Orbitrap mass analyzer, for high resolution (HR) MS/MS detection of NSAIDs. We achieved lower NSAID quantification limits with Q-Orbitrap high resolution mass spectrometry (HRMS/MS) detection than those achieved with the QqQ instrument; however, its main feature is its very high selectivity, which makes HRMS/MS particularly suitable for confirmatory analysis.

Determination of vitamins D2 and D3 in selected food matrices by online high-performance liquid chromatography-gas chromatography-mass spectrometry (HPLC-GC-MS).

PubMed

Nestola, Marco; Thellmann, Andrea

2015-01-01

An online normal-phase liquid chromatography-gas chromatography-mass spectrometry (HPLC-GC-MS) method was developed for the determination of vitamins D2 and D3 in selected food matrices. Transfer of the sample from HPLC to GC was realized by large volume on-column injection; detection was performed with a time-of-flight mass spectrometer (TOF-MS). Typical GC problems in the determination of vitamin D such as sample degradation or sensitivity issues, previously reported in the literature, were not observed. Determination of total vitamin D content was done by quantitation of its pyro isomer based on an isotopically labelled internal standard (ISTD). Extracted ion traces of analyte and ISTD showed cross-contribution, but non-linearity of the calibration curve was not determined inside the chosen calibration range by selection of appropriate quantifier ions. Absolute limits of detection (LOD) and quantitation (LOQ) for vitamins D2 and D3 were calculated as approximately 50 and 150 pg, respectively. Repeatability with internal standard correction was below 2 %. Good agreement between quantitative results of an established high-performance liquid chromatography with UV detection (HPLC-UV) method and HPLC-GC-MS was found. Sterol-enriched margarine was subjected to HPLC-GC-MS and HPLC-MS/MS for comparison, because HPLC-UV showed strong matrix interferences. HPLC-GC-MS produced comparable results with less manual sample cleanup. In summary, online hyphenation of HPLC and GC allowed a minimization in manual sample preparation with an increase of sample throughput.

Systematic assessment of survey scan and MS2-based abundance strategies for label-free quantitative proteomics using high-resolution MS data.

PubMed

Tu, Chengjian; Li, Jun; Sheng, Quanhu; Zhang, Ming; Qu, Jun

2014-04-04

Survey-scan-based label-free method have shown no compelling benefit over fragment ion (MS2)-based approaches when low-resolution mass spectrometry (MS) was used, the growing prevalence of high-resolution analyzers may have changed the game. This necessitates an updated, comparative investigation of these approaches for data acquired by high-resolution MS. Here, we compared survey scan-based (ion current, IC) and MS2-based abundance features including spectral-count (SpC) and MS2 total-ion-current (MS2-TIC), for quantitative analysis using various high-resolution LC/MS data sets. Key discoveries include: (i) study with seven different biological data sets revealed only IC achieved high reproducibility for lower-abundance proteins; (ii) evaluation with 5-replicate analyses of a yeast sample showed IC provided much higher quantitative precision and lower missing data; (iii) IC, SpC, and MS2-TIC all showed good quantitative linearity (R(2) > 0.99) over a >1000-fold concentration range; (iv) both MS2-TIC and IC showed good linear response to various protein loading amounts but not SpC; (v) quantification using a well-characterized CPTAC data set showed that IC exhibited markedly higher quantitative accuracy, higher sensitivity, and lower false-positives/false-negatives than both SpC and MS2-TIC. Therefore, IC achieved an overall superior performance than the MS2-based strategies in terms of reproducibility, missing data, quantitative dynamic range, quantitative accuracy, and biomarker discovery.

Systematic Assessment of Survey Scan and MS2-Based Abundance Strategies for Label-Free Quantitative Proteomics Using High-Resolution MS Data

PubMed Central

2015-01-01

Survey-scan-based label-free method have shown no compelling benefit over fragment ion (MS2)-based approaches when low-resolution mass spectrometry (MS) was used, the growing prevalence of high-resolution analyzers may have changed the game. This necessitates an updated, comparative investigation of these approaches for data acquired by high-resolution MS. Here, we compared survey scan-based (ion current, IC) and MS2-based abundance features including spectral-count (SpC) and MS2 total-ion-current (MS2-TIC), for quantitative analysis using various high-resolution LC/MS data sets. Key discoveries include: (i) study with seven different biological data sets revealed only IC achieved high reproducibility for lower-abundance proteins; (ii) evaluation with 5-replicate analyses of a yeast sample showed IC provided much higher quantitative precision and lower missing data; (iii) IC, SpC, and MS2-TIC all showed good quantitative linearity (R2 > 0.99) over a >1000-fold concentration range; (iv) both MS2-TIC and IC showed good linear response to various protein loading amounts but not SpC; (v) quantification using a well-characterized CPTAC data set showed that IC exhibited markedly higher quantitative accuracy, higher sensitivity, and lower false-positives/false-negatives than both SpC and MS2-TIC. Therefore, IC achieved an overall superior performance than the MS2-based strategies in terms of reproducibility, missing data, quantitative dynamic range, quantitative accuracy, and biomarker discovery. PMID:24635752