Desorption Electrospray Ionization Cyclic Ion Mobility-Mass Spectrometry Imaging for Traumatic Brain Injury Spatial Metabolomics.

Lipidomics focuses on investigating alterations in a wide variety of lipids that harness important information on metabolic processes and disease pathology. However, the vast structural diversity of lipids and the presence of isobaric and isomeric species creates serious challenges in feature identification, particularly in mass spectrometry imaging experiments that lack front-end separations. Ion mobility has emerged as a potential solution to address some of these challenges and is increasingly being utilized as part of mass spectrometry imaging platforms.

Taming Conformational Heterogeneity on Ion Racetrack to Unveil Principles that Drive Membrane Permeation of Cyclosporines.

Our study reveals the underlying principles governing the passive membrane permeability in three large methylated macrocyclic peptides (MeMPs): cyclosporine A (CycA), Alisporivir (ALI), and cyclosporine H (CycH). We determine a series of conformers required for robust passive membrane diffusion and those relevant to other functions, such as binding to protein targets or intermediates, in the presence of solvent additives. We investigate the conformational interconversions and establish correlations with the membrane permeability.

Spatial analysis of renal acetaminophen metabolism and its modulation by 4-methylpyrazole with DESI mass spectrometry imaging.

Acute kidney injury (AKI) is a common complication in acetaminophen (APAP) overdose patients and can negatively impact prognosis. Unfortunately, N-acetylcysteine, which is the standard of care for the treatment of APAP hepatotoxicity does not prevent APAP-induced AKI. We have previously demonstrated the renal metabolism of APAP and identified fomepizole (4-methylpyrazole, 4MP) as a therapeutic option to prevent APAP-induced nephrotoxicity.

-acetylneuraminate pyruvate lyase controls sialylation of muscle glycoproteins essential for muscle regeneration and function.

Deleterious variants in acetylneuraminate pyruvate lyase (NPL) cause skeletal myopathy and cardiac edema in humans and zebrafish, but its physiological role remains unknown. We report generation of mouse models of the disease: , carrying the human p.Arg63Cys variant, and with a 116-bp exonic deletion.

Desorption Electrospray Ionization Mass Spectrometry Imaging Allows Spatial Localization of Changes in Acetaminophen Metabolism in the Liver after Intervention with 4-Methylpyrazole.

Acetaminophen (APAP) overdose is the most common cause of acute liver failure in the US, and hepatotoxicity is initiated by a reactive metabolite which induces characteristic centrilobular necrosis. The only clinically available antidote is -acetylcysteine, which has limited efficacy, and we have identified 4-methylpyrazole (4MP, Fomepizole) as a strong alternate therapeutic option, protecting against generation and downstream effects of the cytotoxic reactive metabolite in the clinically relevant C57BL/6J mouse model and in humans. However, despite the regionally restricted necrosis after APAP, our earlier studies on APAP metabolites in biofluids or whole tissue homogenate lack the spatial information needed to understand region-specific consequences of reactive metabolite formation after APAP overdose.

Structural characterization and analysis of different epimers of neutral glycosphingolipid LcGg4 by ion mobility spectrometry-mass spectrometry.

LcGg4, a neutral glycosphingolipid (GSL) and cancer antigen, its epimers GalNAc-LcGg4 and GlcNAc-LcGg4, and three lipid forms of GalNAc-LcGg4 were studied by mass spectrometry (MS). It was found that different forms of GalNAc-LcGg4 carrying homologous (d16:1/18:0) and (d18:1/18:0) lipids were easily separated and identified using liquid chromatography (LC)-MS. In addition, like gangliosides, homologous lipid forms of GalNAc-LcGg4 showed the same fragmentation pattern, except for a uniform shift of their glycolipid product ions by a certain / number determined by the varied lipid structure.

Exploiting Self-Association to Evaluate Enantiomeric Composition by Cyclic Ion Mobility-Mass Spectrometry.

The characterization of enantiomers is an important analytical challenge in the chemical and life sciences. Thorough evaluation of the purity of chiral molecules is particularly required in the pharmaceutical industry where safety concerns are paramount. Assessment of the enantiomeric composition is still challenging and time-consuming, meaning that alternative approaches are required.

Direct Drug Analysis in Polymeric Implants Using Desorption Electrospray Ionization - Mass Spectrometry Imaging (DESI-MSI).

Purpose: Desorption electrospray ionization mass spectrometry imaging (DESI-MSI) coupled with gas-phase ion mobility spectrometry was used to characterize the drug distribution in polymeric implants before and after exposure to accelerated in vitro release (IVR) media. DESI-MSI provides definitive chemical identification and localization of formulation components, including 2D chemical mapping of individual components with essentially no sample preparation.

Methods: Polymeric implants containing 40% (w/w) entecavir and poly(D,L-lactide) (PLA) were prepared and then exposed to either acidified PBS (pH 2.

Spatial Mapping of Cellular Metabolites Using DESI Ion Mobility Mass Spectrometry.

Spatial mapping of cellular metabolites, such as neurotransmitters and lipids, on the tissue, can increase our understanding of the biological functions of those molecules. Mass spectrometry imaging (MSI) techniques, such as desorption electrospray ionization (DESI), have not demonstrated the ability to perform metabolite analysis at mammalian single cell level yet. However, they can be a valuable tool to provide insight into cellular metabolism in a very small population (tens) of cells.

Proteomics Coupled with Metabolite and Cell Wall Profiling Reveal Metabolic Processes of a Developing Rice Stem Internode.

Internodes of grass stems function in mechanical support, transport, and, in some species, are a major sink organ for carbon in the form of cell wall polymers. This study reports cell wall composition, proteomic, and metabolite analyses of the rice elongating internode. Cellulose, lignin, and xylose increase as a percentage of cell wall material along eight segments of the second rice internode (internode II) at booting stage, from the younger to the older internode segments, indicating active cell wall synthesis.

Analysis of hydroxylated polybrominated diphenyl ethers (OH-BDEs) by supercritical fluid chromatography/mass spectrometry.

Hydroxylated polybrominated diphenyl ethers (OH-BDEs), which have anthropogenic and natural origins, have exhibited neurotoxic and endocrine disrupting effects in humans and wildlife. Therefore, there is an increased interest in the analysis of these compounds in biological matrices in order to assess their potential toxicological risks. Analysis of OH-BDEs is conventionally completed using liquid chromatography/mass spectrometry (LC/MS), or by gas chromatography/mass spectrometry (GC/MS) after derivatization.

Comprehensive bioimaging with fluorinated nanoparticles using breathable liquids.

Fluorocarbons are lipophobic and non-polar molecules that exhibit remarkable biocompatibility, with applications in liquid ventilation and synthetic blood. The unique properties of these compounds have also enabled mass spectrometry imaging of tissues where the fluorocarbons act as a Teflon-like coating for nanostructured surfaces to assist in desorption/ionization. Here we report fluorinated gold nanoparticles (f-AuNPs) designed to facilitate nanostructure imaging mass spectrometry.

Ion mobility-derived collision cross section as an additional measure for lipid fingerprinting and identification.

Despite recent advances in analytical and computational chemistry, lipid identification remains a significant challenge in lipidomics. Ion-mobility spectrometry provides an accurate measure of the molecules' rotationally averaged collision cross-section (CCS) in the gas phase and is thus related to ionic shape. Here, we investigate the use of CCS as a highly specific molecular descriptor for identifying lipids in biological samples.

Synthetic molecules as antibody replacements.

Antibodies are by far the most versatile, valuable, and widely used protein-binding agents. They are essential tools in biological research and are increasingly being developed as therapeutic reagents. However, antibodies have a number of practical limitations, and it would be desirable in many applications to replace them with simpler, more robust synthetic molecules.

Isolation of protein ligands from large peptoid libraries.

The isolation of ligands for large numbers of proteins is an important goal in proteomics. Whereas peptide libraries are rich sources of protein-binding molecules, native peptides have certain undesirable properties, such as sensitivity to proteases that make them less than ideal for some applications. We report here the construction and characterization of large, chemically diverse combinatorial libraries of peptoids (N-substituted oligoglycines).

Immobilized peptides as high-affinity capture agents for self-associating proteins.

There is currently great interest in the fabrication of protein-detecting arrays comprised of large numbers of immobilized protein capture agents. While most efforts in this arena have focused on the use of biomolecules such as antibodies and nucleic acid aptamers as capture agents, synthetic species have many potential advantages. However, synthetic molecules isolated from combinatorial libraries generally do not bind target proteins with the high affinity necessary for array applications.

Microwave-assisted solid-phase synthesis of peptoids.

Microwave irradiation reduces the reaction time for the solid-phase synthesis of peptoids. Under these conditions, coupling of each residue requires only 1 min. The purity and yields of peptoids synthesized in this way are as good as or better than those achieved using standard methods.