Metabolomic profiling of human bladder tissue extracts

INTRODUCTION

Bladder cancer is a common malignancy affecting the urinary tract and effective biomarkers and for which monitoring therapeutic interventions have yet to be identified.

OBJECTIVES

Major aim of this work was to perform metabolomic profiling of human bladder cancer and adjacent normal tissue and to evaluate cancer biomarkers.

METHODS

This study utilized nuclear magnetic resonance (NMR) and high-resolution nanoparticle-based laser desorption/ionization mass spectrometry (LDI-MS) methods to investigate polar metabolite profiles in tissue samples from 99 bladder cancer patients.

RESULTS

Through NMR spectroscopy, six tissue metabolites were identified and quantified as potential indicators of bladder cancer, while LDI-MS allowed detection of 34 compounds which distinguished cancer tissue samples from adjacent normal tissue. Thirteen characteristic tissue metabolites were also found to differentiate bladder cancer tumor grades and thirteen metabolites were correlated with tumor stages. Receiver-operating characteristics analysis showed high predictive power for all three types of metabolomics data, with area under the curve (AUC) values greater than 0.853.

CONCLUSION

To date, this is the first study in which bladder human normal tissues adjacent to cancerous tissues are analyzed using both NMR and MS method. These findings suggest that the metabolite markers identified in this study may be useful for the detection and monitoring of bladder cancer stages and grades.

Characterization of Sulfur-Rich Microbial Organic Matter in Jurassic Carbonates Using Laser-Assisted Mass Spectrometry

Laser desorption-ionization mass spectrometry (MS) shows great potential for in situ molecular analysis of planetary surfaces and microanalysis of space-returned samples or (micro)fossils. Coupled with pyrolysis gas chromatography-mass spectrometry (Py-GC-MS) in ESA's ExoMars project, this technique could help assess further the origin of sulfur-bearing organic matter (OM) recently detected on Mars. To unravel this potential, we analyzed sulfurized microbial OM from ca. 150 million year-old carbonates with laser desorption-ionization mass spectrometry (single- and two-step: LDI-MS and L2MS), in comparison with time-of-flight secondary-ion mass spectrometry (ToF-SIMS), gas chromatography-mass spectrometry (GC-MS), and Py-GC-MS. We show that LDI-MS and L2MS readily detect sulfur-bearing moieties such as (alkyl)thiophenes and (alkyl)benzothiophenes. The mineral matrix, however, made the identification of sulfur-bearing molecules challenging in our L2MS experiment. The dominance of small aromatic hydrocarbons (≤14 carbons) in the LDI-MS and L2MS of the extracted soluble and insoluble OM and of the bulk rock is consistent with the low thermal maturity of the sediment and contrasts with the predominance of larger polycyclic aromatic structures commonly observed in meteorites with these techniques. We detected inorganic ions, in particular VO+, in demineralized OM that likely originate from geoporphyrins, which derive from chlorophylls during sediment diagenesis. Finally, insoluble OM yielded distinct compositions compared with extracted soluble OM, with a greater abundance of ions of mass-to-charge ratio (m/z) over 175 and additional N-moieties. This highlights the potential of laser-assisted MS to decipher the composition of macromolecular OM, in particular to investigate the preservation of biomacromolecules in microfossils. Studies comparing diverse biogenic and abiogenic OM are needed to further assess the use of this technique to search for biosignatures.

Molecular content of nascent soot: Family characterization using two-step laser desorption laser ionization mass spectrometry

Molecules constituting nascent soot particles have been analyzed by two-step laser desorption laser ionization mass spectrometry. Three samples have been collected from a slightly sooting ethylene/air premixed flame with the aim to investigate soot composition in the transition from nucleated to just-grown soot particles. Sampling locations have been selected based on the evolution of the particle size distribution along the flame axis. The mass spectrometric results point to a strong evolution of the molecular composition. Just-nucleated soot is rich in polycyclic aromatic hydrocarbons (PAHs) dominated by medium sizes from 18 to 40 carbon atoms but containing sizes as large as 90 carbon atoms. Most abundant PAHs are in the form of peri-condensed structures. The presence of a large fraction of odd numbered carbon species shows that pentagonal cycles are a common feature of the detected population. Increasing the distance from the burner outlet, i.e., the particle residence time in flame, leads to an evolution of the chemical composition of this population with a major contribution of carbon clusters including also fullerenes up to about 160 carbon atoms. Our data support a scenario in which large PAHs containing pentagonal rings evolve very efficiently upon thermal processing by a series of dehydrogenation and isomerization processes to form fullerenes. This chemistry happens in the early steps of soot growth showing that carbonization is already active at this stage. © 2020 The Authors. Published by Elsevier Inc. on behalf of The Combustion Institute. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Detection of very long-chain hydrocarbons by laser mass spectrometry reveals novel species-, sex-, and age-dependent differences in the cuticular profiles of three Nasonia species

Long-chain cuticular hydrocarbons (CHC) are key components of chemical communication in many insects. The parasitoid jewel wasps from the genus Nasonia use their CHC profile as sex pheromone and for species recognition. The standard analytical tool to analyze CHC is gas chromatography coupled with mass spectrometric detection (GC/MS). This method reliably identifies short- to long-chain alkanes and alkenes, but CHC with more than 40 carbon atoms are usually not detected. Here, we applied two laser mass spectrometry (MS) techniques, namely direct laser desorption/ionization (d)LDI and silver-assisted (Ag-)LDI MS, respectively, to analyze CHC profiles of N. vitripennis, N. giraulti, and N. longicornis directly from the cuticle or extracts. Furthermore, we applied direct analysis in real-time (DART) MS as another orthogonal technique for extracts. The three methods corroborated previous results based on GC/MS, i.e., the production of CHC with carbon numbers between C25 and C40. However, we discovered a novel series of long-chain CHC ranging from C41 to C51/C52. Additionally, several previously unreported singly and doubly unsaturated alkenes in the C31-C39 range were found. Use of principal component analysis (PCA) revealed that the composition of the newly discovered CHC varies significantly between species, sex, and age of the animals. Our study adds to the growing literature on the presence of very long-chain CHC in insects and hints at putative roles in insect communication. Graphical abstract.