| 1. |
- Källback, Patrik, et al.
(författare)
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A Space Efficient Direct Access Data Compression Approach for Mass Spectrometry Imaging
- 2018
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Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 90:6, s. 3676-3682
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Tidskriftsartikel (refereegranskat)abstract
- Advances in mass spectrometry imaging that improve both spatial and mass resolution are resulting in increasingly larger data files that are difficult to handle with current software. We have developed a novel near-lossless compression method with data entropy reduction that reduces the file size significantly. The reduction in data size can be set at four different levels (coarse, medium, fine, and superfine) prior to running the data compression. This can be applied to spectra or spectrum-by-spectrum, or it can be applied to transpose arrays or array-by-array, to efficiently read the data without decompressing the whole data set. The results show that a compression ratio of up to 5.9:1 was achieved for data from commercial mass spectrometry software programs and 55:1 for data from our in-house developed mslQuant program. Comparing the average signals from regions of interest, the maximum deviation was 0.2% between compressed and uncompressed data sets with coarse accuracy for the data entropy reduction. In addition, when accessing the compressed data by selecting a random m/z value using mslQuant, the time to update an image on the computer screen was only slightly increased from 92 (+/- 32) ms (uncompressed) to 114 (+/- 13) ms (compressed). Furthermore, the compressed data can be stored on readily accessible servers for data evaluation without further data reprocessing. We have developed a space efficient, direct access data compression algorithm for mass spectrometry imaging, which can be used for various data-demanding mass spectrometry imaging applications.
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| 2. |
- Källback, Patrik, et al.
(författare)
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Cross-validated Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry Imaging Quantitation Protocol for a Pharmaceutical Drug and Its Drug-Target Effects in the Brain Using Time-of-Flight and Fourier Transform Ion Cyclotron Resonance Analyzers
- 2020
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Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 92:21, s. 14676-14684
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Tidskriftsartikel (refereegranskat)abstract
- Matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) is an established tool in drug development, which enables visualization of drugs and drug metabolites at spatial localizations in tissue sections from different organs. However, robust and accurate quantitation by MALDI-MSI still remains a challenge. We present a quantitative MALDI-MSI method using two instruments with different types of mass analyzers, i.e., time-of-flight (TOF) and Fourier transform ion cyclotron resonance (FTICR) MS, for mapping levels of the in vivo-administered drug citalopram, a selective serotonin reuptake inhibitor, in mouse brain tissue sections. Six different methods for applying calibration standards and an internal standard were evaluated. The optimized method was validated according to authorities' guidelines and requirements, including selectivity, accuracy, precision, recovery, calibration curve, sensitivity, reproducibility, and stability parameters. We showed that applying a dilution series of calibration standards followed by a homogeneously applied, stable, isotopically labeled standard for normalization and a matrix on top of the tissue section yielded similar results to those from the reference method using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The validation results were within specified limits and the brain concentrations for TOF MS (51.1 +/- 4.4 pmol/mg) and FTICR MS (56.9 +/- 6.0 pmol/mg) did not significantly differ from those of the cross-validated LC-MS/MS method (55.0 +/- 4.9 pmol/mg). The effect of in vivo citalopram administration on the serotonin neurotransmitter system was studied in the hippocampus, a brain region that is the principal target of the serotonergic afferents along with the limbic system, and it was shown that serotonin was significantly increased (2-fold), but its metabolite 5-hydroxyindoleacetic acid was not. This study makes a substantial step toward establishing MALDI-MSI as a fully quantitative validated method.
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| 3. |
- Källback, Patrik
(författare)
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Development and Application of Software Tools for Mass Spectrometry Imaging
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Mass spectrometry imaging (MSI) has been extensively used to produce qualitative maps of distributions of proteins, peptides, lipids, neurotransmitters, small molecule pharmaceuticals and their metabolites directly in biological tissue sections. Moreover, during the last 10 years, there has been growing demand to quantify target compounds in tissue sections of various organs. This thesis focuses on development and application of a novel instrument- and manufacturer-independent MSI software suite, msIQuant, in the open access format imzML, which has been developed specifically for quantitative analysis of MSI data. The functionality of msIQuant facilitates automatic generation of calibration curves from series of standards that can be used to determine concentrations of specific analytes. In addition, it provides many tools for image visualization, including modules enabling multiple interpolation, low intensity transparency display, and image fusion and sharpening. Moreover, algorithms and advanced data management modules in msIQuant facilitate management of the large datasets generated following rapid recent increases in the mass and spatial resolutions of MSI instruments, by using spectra transposition and data entropy reduction (at four selectable levels: coarse, medium, fine or superfine) before lossless compression of the data. As described in the thesis, implementation of msIQuant has been exemplified in both quantitative (relative or absolute) and qualitative analyses of distributions of neurotransmitters, endogenous substances and pharmaceutical drugs in brain tissue sections. Our laboratory have developed a molecular-specific approach for the simultaneous imaging and quantitation of multiple neurotransmitters, precursors, and metabolites, such as tyrosine, tryptamine, tyramine, phenethylamine, dopamine, 3-methoxytyramine, serotonin, gamma-aminobutyric acid (GABA), and acetylcholine, in histological tissue sections at high spatial resolution by matrix-assisted laser desorption ionization (MALDI) and desorption electrospray ionization (DESI) MSI. Chemical derivatization by charge-tagging primary amines of analytes significantly increased the sensitivity, enabling mapping of neurotransmitters that were not previously detectable by MSI. The two MSI approaches have been used to directly measure changes in neurotransmitter levels in specific brain structures in animal disease models, which facilitates understanding of biochemical mechanisms of drug treatments. In summary, msIQuant software has proven potency (particularly in combination with the reported derivatization technique) for both qualitative and quantitative analyses. Further developments will enable its implementation in multiple operating system platforms and use for statistical analysis.
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| 4. |
- Källback, Patrik, et al.
(författare)
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msIQuant - Quantitation Software for Mass Spectrometry Imaging Enabling Fast Access, Visualization, and Analysis of Large Data Sets
- 2016
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Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 88:8, s. 4346-4353
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents msIQuant, a novel instrument- and manufacturer-independent quantitative mass spectrometry imaging software suite that uses the standardized open access data format imzML. Its data processing structure enables rapid image display and the analysis of very large data sets (>50 GB) without any data reduction. In addition, msIQuant provides many tools for image visualization including multiple interpolation methods, low intensity transparency display, and image fusion. It also has a quantitation function that automatically generates calibration standard curves from series of standards that can be used to determine the concentrations of specific analytes. Regions-of-interest in a tissue section can be analyzed based on a number of quantities including the number of pixels, average intensity, standard deviation of intensity, and median and quartile intensities. Moreover, the suite's export functions enable simplified postprocessing of data and report creation. We demonstrate its potential through several applications including the quantitation of small molecules such as drugs and neurotransmitters. The msIQuant suite is a powerful tool for accessing and evaluating very large data sets, quantifying drugs and endogenous compounds in tissue areas of interest, and for processing mass spectra and images.
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| 5. |
- Källback, Patrik, et al.
(författare)
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Novel mass spectrometry imaging software assisting labeled normalization and quantitation of drugs and neuropeptides directly in tissue sections
- 2012
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Ingår i: Journal of Proteomics. - : Elsevier BV. - 1874-3919 .- 1876-7737. ; 75:16, s. 4941-4951
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Tidskriftsartikel (refereegranskat)abstract
- MALDI MS imaging has been extensively used to produce qualitative distribution maps of proteins, peptides, lipids, small molecule pharmaceuticals and their metabolites directly in biological tissue sections. There is growing demand to quantify the amount of target compounds in the tissue sections of different organs. We present a novel MS imaging software including protocol for the quantitation of drugs, and for the first time, an endogenous neuropeptide directly in tissue sections. After selecting regions of interest on the tissue section, data is read and processed by the software using several available methods for baseline corrections, subtractions, denoising, smoothing, recalibration and normalization. The concentrations of in vivo administered drugs or endogenous compounds are then determined semi-automatically using either external standard curves, or by using labeled compounds, i.e., isotope labeled analogs as standards. As model systems, we have quantified the distribution of imipramine and tiotropium in the brain and lung of dosed rats. Substance P was quantified in different mouse brain structures, which correlated well with previously reported peptide levels. Our approach facilitates quantitative data processing and labeled standards provide better reproducibility and may be considered as an efficient tool to quantify drugs and endogenous compounds in tissue regions of interest.
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| 6. |
- Shariatgorji, Mohammadreza, et al.
(författare)
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Controlled-pH Tissue Cleanup Protocol for Signal Enhancement of Small Molecule Drugs Analyzed by MALDI-MS Imaging
- 2012
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Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 1520-6882 .- 0003-2700. ; 84:10, s. 4603-4607
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Tidskriftsartikel (refereegranskat)abstract
- The limit of detection of low-molecular weight compounds in tissue sections, analyzed by matrix assisted laser desorption ionization mass spectrometry imaging (MALDI-MSI), was significantly improved by employing sample washing using a pH-controlled buffer solution. The pH of the washing solutions were set at values whereby the target analytes would have low solubility. Washing the tissue sections in the buffered solution resulted in removal of endogenous soluble ionization-suppressing compounds and salts, while the target compound remained in situ with minor or no delocalization during the buffered washing procedure. Two pharmaceutical compounds (cimetidine and imipramine) and one new protease inhibitor compound were successfully used to evaluate the feasibility of the pH-controlled tissue washing protocol for MALDI-MSI. Enhancement in signal-to-noise ratio was achieved by a factor of up to 10.
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| 7. |
- Shariatgorji, Mohammadreza, et al.
(författare)
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Direct targeted quantitative molecular imaging of neurotransmitters in brain tissue sections
- 2014
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Ingår i: Neuron. - : Elsevier BV. - 0896-6273 .- 1097-4199. ; 84:4, s. 697-707
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Tidskriftsartikel (refereegranskat)abstract
- Current neuroimaging techniques have very limited abilities to directly identify and quantify neurotransmitters from brain sections. We have developed a molecular-specific approach for the simultaneous imaging and quantitation of multiple neurotransmitters, precursors, and metabolites, such as tyrosine, tryptamine, tyramine, phenethylamine, dopamine, 3-methoxytyramine, serotonin, GABA, glutamate, acetylcholine, and L-alpha-glycerylphosphorylcholine, in histological tissue sections at high spatial resolutions. The method is employed to directly measure changes in the absolute and relative levels ofneurotransmitters in specific brain structures in animal disease models and in response to drug treatments, demonstrating the power of mass spectrometry imaging in neuroscience.
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| 8. |
- Sugiyama, Eiji, et al.
(författare)
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Detection of a High-Turnover Serotonin Circuit in the Mouse Brain Using Mass Spectrometry Imaging
- 2019
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Ingår i: iScience. - : CELL PRESS. - 2589-0042. ; 20, s. 359-
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Tidskriftsartikel (refereegranskat)abstract
- Monoamine neurotransmitters are released by specialized neurons regulating behavioral, motor, and cognitive functions. Although the localization of monoaminergic neurons in the brain is well known, the distribution and kinetics of monoamines remain unclear. Here, we generated a murine brain atlas of serotonin (5-HT), dopamine (DA), and norepinephrine (NE) levels using mass spectrometry imaging (MSI). We found several nuclei rich in both 5-HT and a catecholamine (DA or NE) and identified the paraventricular nucleus of the thalamus (PVT), where 5-HT and NE are co-localized. The analysis of 5-HT fluctuations in response to acute tryptophan depletion and infusion of isotope-labeled tryptophan in vivo revealed a close kinetic association between the raphe nuclei, PVT, and amygdala but not the other nuclei. Our findings imply the existence of a highly dynamic 5-HT-mediated raphe to PVT pathway that likely plays a role in the brain monoamine system.
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| 9. |
- Vallianatou, Theodosia, et al.
(författare)
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A mass spectrometry imaging approach for investigating how drug-drug interactions influence drug blood-brain barrier permeability
- 2018
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Ingår i: NeuroImage. - : Elsevier BV. - 1053-8119 .- 1095-9572. ; 172, s. 808-816
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Tidskriftsartikel (refereegranskat)abstract
- There is a high need to develop quantitative imaging methods capable of providing detailed brain localization information of several molecular species simultaneously. In addition, extensive information on the effect of the blood-brain barrier on the penetration, distribution and efficacy of neuroactive compounds is required. Thus, we have developed a mass spectrometry imaging method to visualize and quantify the brain distribution of drugs with varying blood-brain barrier permeability. With this approach, we were able to determine blood-brain barrier transport of different drugs and define the drug distribution in very small brain structures (e.g., choroid plexus) due to the high spatial resolution provided. Simultaneously, we investigated the effect of drug-drug interactions by inhibiting the membrane transporter multidrug resistance 1 protein. We propose that the described approach can serve as a valuable analytical tool during the development of neuroactive drugs, as it can provide physiologically relevant information often neglected by traditional imaging technologies.
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| 10. |
- Vallianatou, Theodosia, et al.
(författare)
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Molecular imaging identifies age-related attenuation of acetylcholine in retrosplenial cortex in response to acetylcholinesterase inhibition
- 2019
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Ingår i: Neuropsychopharmacology. - : Springer Science and Business Media LLC. - 0893-133X .- 1740-634X. ; 44, s. 2091-2098
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Tidskriftsartikel (refereegranskat)abstract
- The neurotransmitter of the cholinergic system, acetylcholine plays a major role in the brain's cognitive function and is involved in neurodegenerative disorders. Here, we present age-related alterations of acetylcholine levels after administration of the acetylcholinesterase inhibitor drug tacrine in normal mice. Using a quantitative, robust and molecular-specific mass spectrometry imaging method we found that tacrine administration significantly raised acetylcholine levels in most areas of sectioned mice brains, inter alia the striatum, hippocampus and cortical areas. However, acetylcholine levels in retrosplenial cortex were significantly lower in 14-month-old than in 12-week-old animals following its administration, indicating that normal aging affects the cholinergic system's responsivity. This small brain region is interconnected with an array of brain networks and is involved in numerous cognitive tasks. Simultaneous visualization of distributions of tacrine and its hydroxylated metabolites in the brain revealed a significant decrease in levels of the metabolites in the 14-month-old mice. The results highlight strengths of the imaging technique to simultaneously investigate multiple molecular species and the drug-target effects in specific regions of the brain. The proposed approach has high potential in studies of neuropathological conditions and responses to neuroactive treatments.
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