Trihydroxycholanoyl-taurine in brains of rodents with hepatic encephalopathy.

Hepatic encephalopathy (HE), a neurological disease resulting from liver failure, is difficult to manage and its causes are unclear. Bile acids have been postulated to be involved in the provenance and progression of various diseases including HE. Hence, the characterization of bile acid profiles in the brains of subjects with and without liver failure can provide important clues for the potential treatment of HE.

MALDI imaging directed laser ablation tissue microsampling for data independent acquisition proteomics.

A multimodal workflow for mass spectrometry imaging was developed that combines MALDI imaging with protein identification and quantification by liquid chromatography tandem mass spectrometry (LC-MS/MS). Thin tissue sections were analyzed by MALDI imaging, and the regions of interest (ROI) were identified using a smoothing and edge detection procedure. A midinfrared laser at 3-μm wavelength was used to remove the ROI from the brain tissue section after MALDI mass spectrometry imaging (MALDI MSI).

Infrared laser ablation sampling coupled with data independent high resolution UPLC-IM-MS/MS for tissue analysis.

Infrared laser ablation microsampling was used with data-dependent acquisition (DDA) and ion mobility-enhanced data-independent acquisition (HDMS) for mass spectrometry based bottom-up proteomics analysis of rat brain tissue. Results from HDMS and DDA analyses of the 12 laser ablation sampled tissue sections showed that HDMS consistently identified approximately seven times more peptides and four times more proteins than DDA. To evaluate the impact of ultra-performance liquid chromatography (UPLC) peak congestion on HDMS and DDA analysis, whole tissue digests from rat brain were analyzed at six different UPLC separation times.

Broadband ion mobility deconvolution for rapid analysis of complex mixtures.

High resolving power ion mobility (IM) allows for accurate characterization of complex mixtures in high-throughput IM mass spectrometry (IM-MS) experiments. We previously demonstrated that pure component IM-MS data can be extracted from IM unresolved post-IM/collision-induced dissociation (CID) MS data using automated ion mobility deconvolution (AIMD) software [Matthew Brantley, Behrooz Zekavat, Brett Harper, Rachel Mason, and Touradj Solouki, J. Am.

Automated peak width measurements for targeted analysis of ion mobility unresolved species.

Peak broadening in ion mobility (IM) is a relatively predictable process and abnormally broad peaks can be indicative of the presence of unresolved species. Here, we introduce a new ion mobility peak fitting (IM_FIT) software package for automated and systematic determination of traveling wave ion mobility (TWIM) unresolved species. To identify IM unresolved species, the IM_FIT software generates a trend line by plotting ions' mobility peak widths as a function of their arrival times.

Collision-energy resolved ion mobility characterization of isomeric mixtures.

Existing instrumental resolving power limitations in ion mobility spectrometry (IMS) often restrict adequate characterization of unresolved or co-eluting chemical isomers. Recently, we introduced a novel chemometric deconvolution approach that utilized post-IM collision-induced dissociation (CID) mass spectrometry (MS) data to extract "pure" IM profiles and construct CID mass spectra of individual components from a mixture containing two IM-overlapped components [J. Am.