| 1. |
- Swales, John G., et al.
(författare)
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Quantitation of Endogenous Metabolites in Mouse Tumors Using Mass-Spectrometry Imaging
- 2018
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Ingår i: Analytical Chemistry. - : AMER CHEMICAL SOC. - 0003-2700 .- 1520-6882. ; 90:10, s. 6051-6058
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Tidskriftsartikel (refereegranskat)abstract
- Described is a quantitative-mass-spectrometry-imaging (qMSI) methodology for the analysis of lactate and glutamate distributions in order to delineate heterogeneity among mouse tumor models used to support drug-discovery efficacy testing. We evaluate and report on preanalysis-stabilization methods aimed at improving the reproducibility and efficiency of quantitative assessments of endogenous molecules in tissues. Stability experiments demonstrate that optimum stabilization protocols consist of frozen-tissue embedding, post-tissue-sectioning desiccation, and storage at -80 degrees C of tissue sections sealed in vacuum-tight containers. Optimized stabilization protocols are used in combination with qMSI methodology for the absolute quantitation of lactate and glutamate in tumors, incorporating the use of two different stable-isotope-labeled versions of each analyte and spectral-clustering performed on each tissue section using k-means clustering to allow region-specific, pixel-by-pixel quantitation. Region-specific qMSI was used to screen different tumor models and identify a phenotype that has low lactate heterogeneity, which will enable accurate measurements of lactate modulation in future drug-discovery studies. We conclude that using optimized qMSI protocols, it is possible to quantify endogenous metabolites within tumors, and region-specific quantitation can provide valuable insight into tissue heterogeneity and the tumor microenvironment.
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| 2. |
- Goodwin, Richard J. A., et al.
(författare)
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Exemplifying the Screening Power of Mass Spectrometry Imaging over Label-Based Technologies for Simultaneous Monitoring of Drug and Metabolite Distributions in Tissue Sections
- 2016
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Ingår i: Journal of Biomolecular Screening. - : Elsevier BV. - 1087-0571 .- 1552-454X. ; 21:2, s. 187-193
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Tidskriftsartikel (refereegranskat)abstract
- Mass spectrometry imaging (MSI) provides pharmaceutical researchers with a suite of technologies to screen and assess compound distributions and relative abundances directly from tissue sections and offer insight into drug discovery-applicable queries such as blood-brain barrier access, tumor penetration/retention, and compound toxicity related to drug retention in specific organs/cell types. Label-free MSI offers advantages over label-based assays, such as quantitative whole-body autoradiography (QWBA), in the ability to simultaneously differentiate and monitor both drug and drug metabolites. Such discrimination is not possible by label-based assays if a drug metabolite still contains the radiolabel. Here, we present data exemplifying the advantages of MSI analysis. Data of the distribution of AZD2820, a therapeutic cyclic peptide, are related to corresponding QWBA data. Distribution of AZD2820 and two metabolites is achieved by MSI, which [C-14] AZD2820 QWBA fails to differentiate. Furthermore, the high mass-resolving power of Fourier transform ion cyclotron resonance MS is used to separate closely associated ions.
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| 3. |
- Nilsson, Anna, et al.
(författare)
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Investigating Nephrotoxicity of Polymyxin Derivatives by Mapping Renal Distribution Using Mass Spectrometry Imaging
- 2015
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Ingår i: Chemical Research in Toxicology. - : American Chemical Society (ACS). - 0893-228X .- 1520-5010. ; 28:9, s. 1823-1830
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Tidskriftsartikel (refereegranskat)abstract
- Colistin and polymyxin B are effective treatment options for Gram-negative resistant bacteria but are used as last-line therapy due to their dose-limiting nephrotoxicity. A critical factor in developing safer polymyxin analogues is understanding accumulation of the drugs and their metabolites, which is currently limited due to the lack of effective techniques for analysis of these challenging molecules. Mass spectrometry imaging (MSI) allows direct detection of targets (drugs, metabolites, and endogenous compounds) from tissue sections. The presented study exemplifies the utility of MSI by measuring the distribution of polymyxin B1, colistin, and polymyxin B nonapeptide (PMBN) within dosed rat kidney tissue sections. The label-free MSI analysis revealed that the nephrotoxic compounds (polymyxin B1 and colistin) preferentially accumulated in the renal cortical region. The less nephrotoxic analogue, polymyxin B nonapeptide, was more uniformly distributed throughout the kidney. In addition, metabolites of the dosed compounds were detected by MSI. Kidney homogenates were analyzed using LC/MS/MS to determine total drug exposure and for metabolite identification. To our knowledge, this is the first time such techniques have been utilized to measure the distribution of polymyxin drugs and their metabolites. By simultaneously detecting the distribution of drug and drug metabolites, MSI offers a powerful alternative to tissue homogenization analysis and label or antibody-based imaging.
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| 4. |
- Swales, John G., et al.
(författare)
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Mass Spectrometry Imaging of Cassette-Dosed Drugs for Higher Throughput Pharmacokinetic and Biodistribution Analysis
- 2014
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Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 86:16, s. 8473-8480
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Tidskriftsartikel (refereegranskat)abstract
- Cassette dosing of compounds for preclinical drug plasma pharmacokinetic analysis has been shown to be a powerful strategy within the pharmaceutical industry for increasing throughput while decreasing the number of animals used. Presented here for the first time is data on the application of a cassette dosing strategy for label-free tissue distribution studies. The aim of the study was to image the spatial distribution of eight nonproprietary drugs (haloperidol, bufuralol, midazolam, clozapine, terfenadine, erlotinib, olanzapine, and moxifloxacin) in multiple tissues after oral and intravenous cassette dosing (four compounds per dose route). An array of mass spectrometry imaging technologies, including matrix-assisted laser desorption ionization mass spectrometry imaging (MALDI MSI), liquid extraction surface analysis tandem mass spectrometry (LESA-MS/MS), and desorption electrospray ionization mass spectrometry (DESI-MS) was used. Tissue analysis following intravenous and oral administration of discretely and cassette-dosed compounds demonstrated similar relative abundances across a range of tissues indicating that a cassette dosing approach was applicable. MALDI MSI was unsuccessful in detecting all of the target compounds; therefore, DESI MSL a complementary mass spectrometry imaging technique, was used to detect additional target compounds. In addition, by adapting technology used for tissue profiling (LESA-MS/MS) low spatial resolution mass spectrometry imaging (similar to 1 mm) was possible for all targets across all tissues. This study exemplifies the power of multiplatform MSI analysis within a pharmaceutical research and development (R&D) environment. Furthermore, we have illustrated that the cassette dosing approach can be readily applied to provide combined, label-free pharmacokinetic and drug distribution data at an early stage of the drug discovery/development process while minimizing animal usage.
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