744,943 research outputs found
High-mass-resolution MALDI mass spectrometry imaging of metabolites from formalin-fixed paraffin-embedded tissue.
No full textFormalin-fixed and paraffin-embedded (FFPE) tissue specimens are the gold standard for histological examination, and they provide valuable molecular information in tissue-based research. Metabolite assessment from archived tissue samples has not been extensively conducted because of a lack of appropriate protocols and concerns about changes in metabolite content or chemical state due to tissue processing. We present a protocol for the in situ analysis of metabolite content from FFPE samples using a high-mass-resolution matrix-assisted laser desorption/ionization fourier-transform ion cyclotron resonance mass spectrometry imaging (MALDI-FT-ICR-MSI) platform. The method involves FFPE tissue sections that undergo deparaffinization and matrix coating by 9-aminoacridine before MALDI-MSI. Using this platform, we previously detected ∼1,500 m/z species in the mass range m/z 50-1,000 in FFPE samples; the overlap compared with fresh frozen samples is 72% of m/z species, indicating that metabolites are largely conserved in FFPE tissue samples. This protocol can be reproducibly performed on FFPE tissues, including small samples such as tissue microarrays and biopsies. The procedure can be completed in a day, depending on the size of the sample measured and raster size used. Advantages of this approach include easy sample handling, reproducibility, high throughput and the ability to demonstrate molecular spatial distributions in situ. The data acquired with this protocol can be used in research and clinical practice
Ultra-High Mass Resolving Power, Mass Accuracy, and Dynamic Range MALDI Mass Spectrometry Imaging by 21-T FT-ICR MS
No full textDetailed characterization of complex biological surfaces by matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging (MSI) requires instrumentation that is capable of high mass resolving power, mass accuracy, and dynamic range. Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) offers the highest mass spectral performance for MALDI MSI experiments, and often reveals molecular features that are unresolved on lower performance instrumentation. Higher magnetic field strength improves all performance characteristics of FT-ICR; mass resolving power improves linearly, while mass accuracy and dynamic range improve quadratically with magnetic field strength. Here, MALDI MSI at 21T is demonstrated for the first time: mass resolving power in excess of 1 600 000 (at m/z 400), root-mean-square mass measurement accuracy below 100 ppb, and dynamic range per pixel over 500:1 were obtained from the direct analysis of biological tissue sections. Molecular features with m/z differences as small as 1.79 mDa were resolved and identified with high mass accuracy. These features allow for the separation and identification of lipids to the underlying structures of tissues. The unique molecular detail, accuracy, sensitivity, and dynamic range combined in a 21T MALDI FT-ICR MSI experiment enable researchers to visualize molecular structures in complex tissues that have remained hidden until now. The instrument described allows for future innovative, such as high-end studies to unravel the complexity of biological, geological, and engineered organic material surfaces with an unsurpassed detail.</p
Galaxy And Mass Assembly (GAMA) : galaxy close pairs, mergers and the future fate of stellar mass
No full textASGR acknowledges STFC and SUPA funding that were used to do this work. GAMA is funded by the STFC (UK), the ARC (Australia), the AAO and the participating institutions.We use a highly complete subset of the Galaxy And Mass Assembly II (GAMA-II) redshift sample to fully describe the stellar mass dependence of close pairs and mergers between 10(8) and 10(12)M(circle dot). Using the analytic form of this fit we investigate the total stellar mass accreting on to more massive galaxies across all mass ratios. Depending on how conservatively we select our robust merging systems, the fraction of mass merging on to more massive companions is 2.0-5.6 per cent. Using the GAMA-II data we see no significant evidence for a change in the close pair fraction between redshift z = 0.05 and 0.2. However, we find a systematically higher fraction of galaxies in similar mass close pairs compared to published results over a similar redshift baseline. Using a compendium of data and the function gamma(M) = A(1 + z)(m) to predict the major close pair fraction, we find fitting parameters of A = 0.021 +/- 0.001 and m = 1.53 +/- 0.08, which represents a higher low-redshift normalization and shallower power-law slope than recent literature values. We find that the relative importance of in situ star formation versus galaxy merging is inversely correlated, with star formation dominating the addition of stellar material below M* and merger accretion events dominating beyond M*. We find mergers have a measurable impact on the whole extent of the galaxy stellar mass function (GSMF), manifest as a deepening of the 'dip' in the GSMF over the next similar to Gyr and an increase in M* by as much as 0.01-0.05 dex.Peer reviewe
Structural study of manganese(III)-tetraarylporphyrin complexes by fast-atom-bombardment mass spectrometry.
No full textBody mass index cut offs to define thinness in children and adolescents: international survey
No full textOBJECTIVE: To determine cut offs to define thinness in children and adolescents, based on body mass index at age 18 years.DESIGN: International survey of six large nationally representative cross sectional studies on growth. SETTING: Brazil, Great Britain, Hong Kong, the Netherlands, Singapore, and the United States. SUBJECTS: 97 876 males and 94 851 females from birth to 25 years. MAIN OUTCOME MEASURE: Body mass index (BMI, weight/height(2)). RESULTS: The World Health Organization defines grade 2 thinness in adults as BMI <17. This same cut off, applied to the six datasets at age 18 years, gave mean BMI close to a z score of -2 and 80% of the median. Thus it matches existing criteria for wasting in children based on weight for height. For each dataset, centile curves were drawn to pass through the cut off of BMI 17 at 18 years. The resulting curves were averaged to provide age and sex specific cut-off points from 2-18 years. Similar cut offs were derived based on BMI 16 and 18.5 at 18 years, together providing definitions of thinness grades 1, 2, and 3 in children and adolescents consistent with the WHO adult definitions. CONCLUSIONS: The proposed cut-off points should help to provide internationally comparable prevalence rates of thinness in children and adolescent
Drift tube ion mobility and four-dimensional molecular feature extraction enable data-independent tandem mass spectrometric 'omics' analysis without quadrupole selection
No full textRATIONALE: Quadrupole-based tandem mass spectrometry (MS/MS) plays a critical role in 'omics' studies. However, when a particular m/z precursor is selected by the quadrupole, ions other than the precursor are not transmitted through, and the sensitivity and dynamic range thus diminish. Therefore, separation techniques such as ion mobility (IM) are coupled with MS/MS to improve it
[M-H](+) ions in 3-alkyl substituted indoles detected by electrospray mass spectrometry
No full textA series of six C-3 alkyl-substituted indole derivatives were investigated using electrospray, ionization quadrupole time-of-flight mass spectrometry (ESI-QTOF-MS). Anomalous [M-H](+) ions, were detected. Three possible pathways forming [M-H](+) were proposed. MS/MS spectra and radical, trapping experiment support direct loss of hydride anion. Notably, the positions losing the hydride, anion were different for these compounds, and were tentatively confirmed by D-labeled and MS/MS, spectra. Both steric hindrance and electronic effect might contribute the difference. (c) 2014 Elsevier B.V. All rights reserved
Time-Resolved Imaging of High Mass Proteins and Metastable Fragments Using Matrix-Assisted Laser Desorption/Ionization, Axial Time-of-Flight Mass Spectrometry, and TPX3CAM
No full text[Image: see text] The Timepix (TPX) is a position- and time-sensitive pixelated charge detector that can be coupled with time-of-flight mass spectrometry (TOF MS) in combination with microchannel plates (MCPs) for the spatially and temporally resolved detection of biomolecules. Earlier generation TPX detectors used in previous studies were limited by a moderate time resolution (at best 10 ns) and single-stop detection for each pixel that hampered the detection of ions with high mass-to-charge (m/z) values at high pixel occupancies. In this study, we have coupled an MCP-phosphor screen-TPX3CAM detection assembly that contains a silicon-coated TPX3 chip to a matrix-assisted laser desorption/ionization (MALDI)-axial TOF MS. A time resolution of 1.5625 ns, per-pixel multihit functionality, simultaneous measurement of TOF and time-over-threshold (TOT) values, and kHz readout rates of the TPX3 extended the m/z detection range of the TPX detector family. The detection of singly charged intact Immunoglobulin M ions of m/z value approaching 1 × 10(6) Da has been demonstrated. We also discuss the utilization of additional information on impact coordinates and TOT provided by the TPX3 compared to conventional MS detectors for the enhancement of the quality of the mass spectrum in terms of signal-to-noise (S/N) ratio. We show how the reduced dead time and event-based readout in TPX3 compared to the TPX improves the sensitivity of high m/z detection in both low and high mass measurements (m/z range: 757–970,000 Da). We further exploit the imaging capabilities of the TPX3 detector for the spatial and temporal separation of neutral fragments generated by metastable decay at different locations along the field-free flight region by simultaneous application of deflection and retarding fields
Mass spectrometric identification of polycycloaddition of arylchlorocarbenes and fluorenylidene to buckministerfullerene
No full textPT: J; CR: ALLEMAND PM, 1991, J AM CHEM SOC, V113, P1050 DOYLE MP, 1986, TETRAHEDRON LETT, V27, P4395 DOYLE MP, 1987, CHEM DIAZIRINES, CH8 KOMATSU, 1993, CHEM LETT, P2163 KROTO HW, 1985, NATURE, V318, P162 KRUSIC PJ, 1991, SCIENCE, V254, P1183 MOSS RA, 1989, ACCOUNTS CHEM RES, V22, P15 SHI S, 1992, J AM CHEM SOC, V114, P10656 SOUNDARARAJAN N, 1988, J AM CHEM SOC, V110, P7143 SUZUKI T, 1991, SCIENCE, V254, P1186 VASELLA A, 1992, ANGEW CHEM INT EDIT, V31, P1338 WUDL F, 1992, ACCOUNTS CHEM RES, V25, P157 WUDL F, 1993, BUCKMINSTERFULLERENE, CH13 XIE QS, 1992, J AM CHEM SOC, V114, P3978; NR: 14; TC: 1; J9: ORG MASS SPECTROM; PG: 3; GA: NY268Source type: Electronic(1
Applications of a trypsin immobilized bioreactor coupled with mass spectrometry
No full textThe work describes use of a Tripsin Immobilized Bioreactor coupled with mass spectrometry ESI-MS/M
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