@article{mellinger_garrard_khodjaniyazova_rabbani_gamcsik_muddiman_2022, title={Multiple Infusion Start Time Mass Spectrometry Imaging of Dynamic SIL-Glutathione Biosynthesis Using Infrared Matrix-Assisted Laser Desorption Electrospray Ionization}, volume={21}, ISSN={["1535-3907"]}, DOI={10.1021/acs.jproteome.1c00636}, abstractNote={Due to the high association of glutathione metabolism perturbation with a variety of disease states, there is a dire need for analytical techniques to study glutathione kinetics. Additionally, the elucidation of microenvironmental effects on changes in glutathione metabolism would significantly improve our understanding of the role of glutathione in disease. We therefore present a study combining a multiple infusion start time protocol, stable isotope labeling technology, infrared matrix-assisted laser desorption electrospray ionization, and high-resolution accurate mass-mass spectrometry imaging to study spatial changes in glutathione kinetics across in sectioned mouse liver tissues. After injecting a mouse with the isotopologues [2-13C,15N]-glycine, [1,2-13C2]-glycine, and [1,2-13C2,15N]-glycine at three different time points, we were able to fully resolve and spatially map their metabolism into three isotopologues of glutathione and calculate their isotopic enrichment in glutathione. We created a tool in the open-source mass spectrometry imaging software MSiReader to accurately compute the percent isotope enrichment (PIE) of these labels in glutathione and visualize them in heat-maps of the tissue sections. In areas of high flux, we found that each label enriched an approximate median of 1.6%, 1.8%, and 1.5%, respectively, of the glutathione product pool measured in each voxel. This method may be adapted to study the heterogeneity of glutathione flux in diseased versus healthy tissues.}, number={3}, journal={JOURNAL OF PROTEOME RESEARCH}, author={Mellinger, Allyson L. and Garrard, Kenneth P. and Khodjaniyazova, Sitora and Rabbani, Zahid N. and Gamcsik, Michael P. and Muddiman, David C.}, year={2022}, month={Mar}, pages={747–757} }
 @article{garrard_ekelöf_khodjaniyazova_bagley_muddiman_2020, title={A Versatile Platform for Mass Spectrometry Imaging of Arbitrary Spatial Patterns}, volume={31}, ISSN={1044-0305 1879-1123}, url={http://dx.doi.org/10.1021/jasms.0c00128}, DOI={10.1021/jasms.0c00128}, abstractNote={A vision-system driven platform, RastirX, has been constructed for mass spectrometry imaging (MSI) of arbitrary two-dimensional patterns. The user identifies a region of interest (ROI) by drawing on a live video image of the sample with the computer mouse. Motion commands are automatically generated to move the sample to acquire scan data for the pixels in the ROI. Synchronization of sample stage motion with laser firing and mass spectrometer (MS) scan acquisition is fully automated. RastirX saves a co-registered optical image and the scan location information needed to convert raw MS data into imzML format. Imaging an arbitrarily shaped ROI instead of the minimal enclosing rectangle reduces contamination from off-sample material and significantly reduces acquisition time.}, number={12}, journal={Journal of the American Society for Mass Spectrometry}, publisher={American Chemical Society (ACS)}, author={Garrard, Kenneth P. and Ekelöf, Måns and Khodjaniyazova, Sitora and Bagley, M. Caleb and Muddiman, David C.}, year={2020}, month={Jun}, pages={2547–2552} }
 @article{bai_khodjaniyazova_garrard_muddiman_2020, title={Three-Dimensional Imaging with Infrared Matrix-Assisted Laser Desorption Electrospray Ionization Mass Spectrometry}, volume={31}, ISSN={["1879-1123"]}, DOI={10.1021/jasms.9b00066}, abstractNote={Mass spectrometry imaging as a field has pushed its frontiers to three dimensions. Most three-dimensional mass spectrometry imaging (3D MSI) approaches require serial sectioning that results in a loss of biological information between analyzed slices and difficulty in reconstruction of 3D images. In this contribution, infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) was demonstrated to be applicable for 3D MSI that does not require sectioning because IR laser ablates material on a micrometer scale. A commercially available over-the-counter pharmaceutical was used as a model to demonstrate the feasibility of IR-MALDESI for 3D MSI. Depth resolution (i.e., z-resolution) as a function of laser energy levels and density of ablated material was investigated. The best achievable depth resolution from a pill was 2.3 μm at 0.3 mJ/pulse. 2D and 3D MSI were performed on the tablet to show the distribution of pill-specific molecules. A 3D MSI analysis on a region of interest of 15 × 15 voxels across 50 layers was performed. Our results demonstrate that IR-MALDESI is feasible with 3D MSI on a pill, and future work will be focused on analyses of biological tissues.}, number={2}, journal={JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY}, author={Bai, Hongxia and Khodjaniyazova, Sitora and Garrard, Kenneth P. and Muddiman, David}, year={2020}, month={Feb}, pages={292–297} }
 @article{khodjaniyazova_hanne_cole_muddiman_2019, title={Mass spectrometry imaging (MSI) of fresh bones using infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI)}, volume={11}, ISSN={["1759-9679"]}, url={https://doi.org/10.1039/C9AY01886G}, DOI={10.1039/c9ay01886g}, abstractNote={Direct analysis and IR-MALDESI mass spectrometry imaging of fresh mouse bones that underwent no chemical treatments other than flash-freezing.}, number={46}, journal={ANALYTICAL METHODS}, publisher={Royal Society of Chemistry (RSC)}, author={Khodjaniyazova, Sitora and Hanne, Nicholas J. and Cole, Jacqueline H. and Muddiman, David C.}, year={2019}, month={Dec}, pages={5929–5938} }
 @article{nazari_ekelof_khodjaniyazova_elsen_williams_muddiman_2017, title={Direct screening of enzyme activity using infrared matrix-assisted laser desorption electrospray ionization}, volume={31}, ISSN={["1097-0231"]}, DOI={10.1002/rcm.7971}, abstractNote={RationaleHigh‐throughput screening (HTS) is a critical step in the drug discovery process. However, most mass spectrometry (MS)‐based HTS methods require sample cleanup steps prior to analysis. In this work we present the utility of infrared matrix‐assisted laser desorption electrospray ionization (IR‐MALDESI) for monitoring an enzymatic reaction directly from a biological buffer system with no sample cleanup and at high throughput.}, number={22}, journal={RAPID COMMUNICATIONS IN MASS SPECTROMETRY}, author={Nazari, Milad and Ekelof, Mans and Khodjaniyazova, Sitora and Elsen, Nathaniel L. and Williams, Jon D. and Muddiman, David C.}, year={2017}, month={Nov}, pages={1868–1874} }