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Huang X, Wang R, Wang Y, Chen C, Liu S. Investigation on property differences of ginseng and American ginseng by spatial metabolomics of neurochemicals with desorption electrospray ionization mass spectrometry imaging. JOURNAL OF ETHNOPHARMACOLOGY 2023; 303:116006. [PMID: 36516905 DOI: 10.1016/j.jep.2022.116006] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2022] [Revised: 11/23/2022] [Accepted: 11/30/2022] [Indexed: 06/17/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE The properties are the body's response to traditional Chinese medicine (TCM). The essence of traditional Chinese medicine properties are cold, hot, warm, and cool. In the theory of traditional Chinese medicine, ginseng is warm and American ginseng is cool, they present two opposite properties. The material basis of property differences and effect mechanism of property degree need further investigation. AIM OF THE STUDY The aim of this work was to screen out the neurochemicals related to warm and cool properties of ginseng and American ginseng, and investigate the distributions of identified neurochemicals in rat brain and the metabolic mechanism. MATERIALS AND METHODS Spatial metabolomics was applied to study the effects of ginseng and American ginseng on the distributions of neurochemicals in rat brain by desorption electrospray ionization mass spectrometry imaging (DESI-MSI). Based on discriminant coefficients in partial least square discriminant analysis (PLS-DA) processing, neurochemicals related to warm and cool properties were classified. In addition, the score contributions of the neurochemicals markers could be used to evaluate the warm and cool property degrees. RESULTS A total of 25 neurochemicals were imaged and identified in brain section. The distribution regions of main neurochemicals were consistent with in sagittal and coronal sections of brain reported in literature. 17 neurochemicals were classified as warm markers. Meanwhile, 8 neurochemicals were identified as cool markers, correlated with the cool properties of American ginseng. It demonstrated that the score contributions of the 25 neurochemicals markers could be used to evaluate the warm and cool property degrees. Based on the regulatory effects of neurochemicals, the warm markers could promote the body's energy metabolism, improve the function of endocrine system, and enhance the excitability of central nervous system. The cool property markers have reduced excitability of central nervous system, weakened metabolism and stress response ability, thus presented the biological activity of cool and cold. CONCLUSIONS Our findings provided a rapid and effective visualization method for the spatial distribution and metabolism of small molecular neurochemicals in rat brain. DESI-MSI was a reference methodology for evaluating the properties of TCM.
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Affiliation(s)
- Xin Huang
- Jilin Ginseng Academy, Changchun University of Chinese Medicine, Changchun, 130117, PR China.
| | - Rui Wang
- Jilin Ginseng Academy, Changchun University of Chinese Medicine, Changchun, 130117, PR China.
| | - Yikai Wang
- Jilin Ginseng Academy, Changchun University of Chinese Medicine, Changchun, 130117, PR China.
| | - Changbao Chen
- Jilin Ginseng Academy, Changchun University of Chinese Medicine, Changchun, 130117, PR China.
| | - Shuying Liu
- Jilin Ginseng Academy, Changchun University of Chinese Medicine, Changchun, 130117, PR China; Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, PR China.
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2
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Deulofeu M, Peña-Méndez EM, Vaňhara P, Havel J, Moráň L, Pečinka L, Bagó-Mas A, Verdú E, Salvadó V, Boadas-Vaello P. Artificial Neural Networks Coupled with MALDI-TOF MS Serum Fingerprinting To Classify and Diagnose Pathological Pain Subtypes in Preclinical Models. ACS Chem Neurosci 2022; 14:300-311. [PMID: 36584284 PMCID: PMC9853500 DOI: 10.1021/acschemneuro.2c00665] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Pathological pain subtypes can be classified as either neuropathic pain, caused by a somatosensory nervous system lesion or disease, or nociplastic pain, which develops without evidence of somatosensory system damage. Since there is no gold standard for the diagnosis of pathological pain subtypes, the proper classification of individual patients is currently an unmet challenge for clinicians. While the determination of specific biomarkers for each condition by current biochemical techniques is a complex task, the use of multimolecular techniques, such as matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), combined with artificial intelligence allows specific fingerprints for pathological pain-subtypes to be obtained, which may be useful for diagnosis. We analyzed whether the information provided by the mass spectra of serum samples of four experimental models of neuropathic and nociplastic pain combined with their functional pain outcomes could enable pathological pain subtype classification by artificial neural networks. As a result, a simple and innovative clinical decision support method has been developed that combines MALDI-TOF MS serum spectra and pain evaluation with its subsequent data analysis by artificial neural networks and allows the identification and classification of pathological pain subtypes in experimental models with a high level of specificity.
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Affiliation(s)
- Meritxell Deulofeu
- Research
Group of Clinical Anatomy, Embryology and Neuroscience (NEOMA), Department
of Medical Sciences, University of Girona, Girona, Catalonia 17003, Spain,Department
of Chemistry, Faculty of Science, Masaryk
University, Kamenice 5/A14, 625 00 Brno, Czech Republic,Department
of Histology and Embryology, Faculty of Medicine, Masaryk University, 62500 Brno, Czech Republic
| | - Eladia M. Peña-Méndez
- Department
of Chemistry, Analytical Chemistry Division, Faculty of Sciences, University of La Laguna, 38204 San Cristóbal de
La Laguna, Tenerife, Spain
| | - Petr Vaňhara
- Department
of Histology and Embryology, Faculty of Medicine, Masaryk University, 62500 Brno, Czech Republic,International
Clinical Research Center, St. Anne’s
University Hospital, 656
91 Brno, Czech Republic
| | - Josef Havel
- Department
of Chemistry, Faculty of Science, Masaryk
University, Kamenice 5/A14, 625 00 Brno, Czech Republic,International
Clinical Research Center, St. Anne’s
University Hospital, 656
91 Brno, Czech Republic
| | - Lukáš Moráň
- Department
of Histology and Embryology, Faculty of Medicine, Masaryk University, 62500 Brno, Czech Republic,Research
Centre for Applied Molecular Oncology (RECAMO), Masaryk Memorial Cancer Institute, 62500 Brno, Czech Republic
| | - Lukáš Pečinka
- Department
of Chemistry, Faculty of Science, Masaryk
University, Kamenice 5/A14, 625 00 Brno, Czech Republic,International
Clinical Research Center, St. Anne’s
University Hospital, 656
91 Brno, Czech Republic
| | - Anna Bagó-Mas
- Research
Group of Clinical Anatomy, Embryology and Neuroscience (NEOMA), Department
of Medical Sciences, University of Girona, Girona, Catalonia 17003, Spain
| | - Enrique Verdú
- Research
Group of Clinical Anatomy, Embryology and Neuroscience (NEOMA), Department
of Medical Sciences, University of Girona, Girona, Catalonia 17003, Spain
| | - Victoria Salvadó
- Department
of Chemistry, Faculty of Science, University
of Girona, 17071 Girona, Catalonia, Spain,
| | - Pere Boadas-Vaello
- Research
Group of Clinical Anatomy, Embryology and Neuroscience (NEOMA), Department
of Medical Sciences, University of Girona, Girona, Catalonia 17003, Spain,
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3
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Fournelle F, Lauzon N, Yang E, Chaurand P. Metal-Assisted Laser Desorption Ionization Imaging Mass Spectrometry for Biological and Forensic Applications. Microchem J 2022. [DOI: 10.1016/j.microc.2022.108294] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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4
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Anapindi KDB, Romanova EV, Checco JW, Sweedler JV. Mass Spectrometry Approaches Empowering Neuropeptide Discovery and Therapeutics. Pharmacol Rev 2022; 74:662-679. [PMID: 35710134 DOI: 10.1124/pharmrev.121.000423] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The discovery of insulin in the early 1900s ushered in the era of research related to peptides acting as hormones and neuromodulators, among other regulatory roles. These essential gene products are found in all organisms, from the most primitive to the most evolved, and carry important biologic information that coordinates complex physiology and behavior; their misregulation has been implicated in a variety of diseases. The evolutionary origins of at least 30 neuropeptide signaling systems have been traced to the common ancestor of protostomes and deuterostomes. With the use of relevant animal models and modern technologies, we can gain mechanistic insight into orthologous and paralogous endogenous peptides and translate that knowledge into medically relevant insights and new treatments. Groundbreaking advances in medicine and basic science influence how signaling peptides are defined today. The precise mechanistic pathways for over 100 endogenous peptides in mammals are now known and have laid the foundation for multiple drug development pipelines. Peptide biologics have become valuable drugs due to their unique specificity and biologic activity, lack of toxic metabolites, and minimal undesirable interactions. This review outlines modern technologies that enable neuropeptide discovery and characterization, and highlights lessons from nature made possible by neuropeptide research in relevant animal models that is being adopted by the pharmaceutical industry. We conclude with a brief overview of approaches/strategies for effective development of peptides as drugs. SIGNIFICANCE STATEMENT: Neuropeptides, an important class of cell-cell signaling molecules, are involved in maintaining a range of physiological functions. Since the discovery of insulin's activity, over 100 bioactive peptides and peptide analogs have been used as therapeutics. Because these are complex molecules not easily predicted from a genome and their activity can change with subtle chemical modifications, mass spectrometry (MS) has significantly empowered peptide discovery and characterization. This review highlights contributions of MS-based research towards the development of therapeutic peptides.
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Affiliation(s)
- Krishna D B Anapindi
- Department of Chemistry and the Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-Champaign, Urbana, Illinois (K.D.B.A., E.V.R., J.V.S.) and Department of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska (J.W.C.)
| | - Elena V Romanova
- Department of Chemistry and the Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-Champaign, Urbana, Illinois (K.D.B.A., E.V.R., J.V.S.) and Department of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska (J.W.C.)
| | - James W Checco
- Department of Chemistry and the Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-Champaign, Urbana, Illinois (K.D.B.A., E.V.R., J.V.S.) and Department of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska (J.W.C.)
| | - Jonathan V Sweedler
- Department of Chemistry and the Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-Champaign, Urbana, Illinois (K.D.B.A., E.V.R., J.V.S.) and Department of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska (J.W.C.)
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5
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De La Toba EA, Bell SE, Romanova EV, Sweedler JV. Mass Spectrometry Measurements of Neuropeptides: From Identification to Quantitation. ANNUAL REVIEW OF ANALYTICAL CHEMISTRY (PALO ALTO, CALIF.) 2022; 15:83-106. [PMID: 35324254 DOI: 10.1146/annurev-anchem-061020-022048] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Neuropeptides (NPs), a unique class of neuronal signaling molecules, participate in a variety of physiological processes and diseases. Quantitative measurements of NPs provide valuable information regarding how these molecules are differentially regulated in a multitude of neurological, metabolic, and mental disorders. Mass spectrometry (MS) has evolved to become a powerful technique for measuring trace levels of NPs in complex biological tissues and individual cells using both targeted and exploratory approaches. There are inherent challenges to measuring NPs, including their wide endogenous concentration range, transport and postmortem degradation, complex sample matrices, and statistical processing of MS data required for accurate NP quantitation. This review highlights techniques developed to address these challenges and presents an overview of quantitative MS-based measurement approaches for NPs, including the incorporation of separation methods for high-throughput analysis, MS imaging for spatial measurements, and methods for NP quantitation in single neurons.
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Affiliation(s)
- Eduardo A De La Toba
- Department of Chemistry, University of Illinois Urbana-Champaign, Urbana, Illinois, USA;
- Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-Champaign, Urbana, Illinois, USA
| | - Sara E Bell
- Department of Chemistry, University of Illinois Urbana-Champaign, Urbana, Illinois, USA;
- Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-Champaign, Urbana, Illinois, USA
| | - Elena V Romanova
- Department of Chemistry, University of Illinois Urbana-Champaign, Urbana, Illinois, USA;
- Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-Champaign, Urbana, Illinois, USA
| | - Jonathan V Sweedler
- Department of Chemistry, University of Illinois Urbana-Champaign, Urbana, Illinois, USA;
- Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-Champaign, Urbana, Illinois, USA
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6
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Vu NQ, DeLaney K, Li L. Neuropeptidomics: Improvements in Mass Spectrometry Imaging Analysis and Recent Advancements. Curr Protein Pept Sci 2021; 22:158-169. [PMID: 33200705 PMCID: PMC8330971 DOI: 10.2174/1389203721666201116115708] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Revised: 05/29/2020] [Accepted: 07/23/2020] [Indexed: 12/13/2022]
Abstract
Neuropeptides are an important class of endogenous peptides in the nervous system that regulate physiological functions such as feeding, glucose homeostasis, pain, memory, reproduction, and many others. In order to understand the functional role of neuropeptides in diseases or disorders, studies investigating their dysregulation in terms of changes in abundance and localization must be carried out. As multiple neuropeptides are believed to play a functional role in each physiological process, techniques capable of global profiling multiple neuropeptides simultaneously are desired. Mass spectrometry is well-suited for this goal due to its ability to perform untargeted measurements without prior comprehensive knowledge of the analytes of interest. Mass spectrometry imaging (MSI) is particularly useful because it has the capability to image a large variety of peptides in a single experiment without labeling. Like all analytical techniques, careful sample preparation is critical to successful MSI analysis. The first half of this review focuses on recent developments in MSI sample preparation and instrumentation for analyzing neuropeptides and other biomolecules in which the sample preparation technique may be directly applicable for neuropeptide analysis. The benefit offered by incorporating these techniques is shown as improvement in a number of observable neuropeptides, enhanced signal to noise, increased spatial resolution, or a combination of these aspects. The second half of this review focuses on recent biological discoveries about neuropeptides resulting from these improvements in MSI analysis. The recent progress in neuropeptide detection and analysis methods, including the incorporation of various tissue washes, matrices, instruments, ionization sources, and computation approaches combined with the advancements in understanding neuropeptide function in a variety of model organisms, indicates the potential for the utilization of MSI analysis of neuropeptides in clinical settings.
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Affiliation(s)
- Nhu Q. Vu
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, WI 53706, USA
| | - Kellen DeLaney
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, WI 53706, USA
| | - Lingjun Li
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, WI 53706, USA
- School of Pharmacy, University of Wisconsin-Madison, 777 Highland Avenue, Madison, WI 53705, USA
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7
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Novel imaging and related techniques for studies of diseases of the central nervous system: a review. Cell Tissue Res 2020; 380:415-424. [PMID: 32072308 DOI: 10.1007/s00441-020-03183-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Accepted: 01/29/2020] [Indexed: 10/25/2022]
Abstract
Imaging technologies for the analysis of the central nervous system are rapidly developing. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry imaging, tracer-based magnetic resonance imaging, CLARITY technology and optogenetics can be used to visualize small molecules in brain tissues, the interstitial system of the brain and neuronal circuits in whole-brain samples. These tools serve as powerful technical means to explore the mechanisms underlying disease models and to evaluate the effects of drugs. Here, we review the constituting principles of these imaging techniques and describe their applications in the field of neuroscience.
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8
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Corbière A, Vaudry H, Chan P, Walet-Balieu ML, Lecroq T, Lefebvre A, Pineau C, Vaudry D. Strategies for the Identification of Bioactive Neuropeptides in Vertebrates. Front Neurosci 2019; 13:948. [PMID: 31619945 PMCID: PMC6759750 DOI: 10.3389/fnins.2019.00948] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Accepted: 08/22/2019] [Indexed: 11/13/2022] Open
Abstract
Neuropeptides exert essential functions in animal physiology by controlling e.g., reproduction, development, growth, energy homeostasis, cardiovascular activity and stress response. Thus, identification of neuropeptides has been a very active field of research over the last decades. This review article presents the various methods used to discover novel bioactive peptides in vertebrates. Initially identified on the basis of their biological activity, some neuropeptides have also been discovered for their ability to bind/activate a specific receptor or based on their biochemical characteristics such as C-terminal amidation which concerns half of the known neuropeptides. More recently, sequencing of the genome of many representative species has facilitated peptidomic approaches using mass spectrometry and in silico screening of genomic libraries. Through these different approaches, more than a hundred of bioactive neuropeptides have already been identified in vertebrates. Nevertheless, researchers continue to find new neuropeptides or to identify novel functions of neuropeptides that had not been detected previously, as it was recently the case for nociceptin.
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Affiliation(s)
- Auriane Corbière
- Normandie Univ, UNIROUEN, Inserm, Laboratory of Neuronal and Neuroendocrine Communication and Differentiation, Neuropeptides, Neuronal Death and Cell Plasticity Team, Rouen, France
| | - Hubert Vaudry
- Normandie Univ, UNIROUEN, Inserm, Laboratory of Neuronal and Neuroendocrine Communication and Differentiation, Neuropeptides, Neuronal Death and Cell Plasticity Team, Rouen, France.,Normandie Univ, UNIROUEN, Regional Cell Imaging Platform of Normandy (PRIMACEN), Rouen, France
| | - Philippe Chan
- Normandie Univ, UNIROUEN, Rouen Proteomic Platform (PISSARO), Institute for Research and Innovation in Biomedicine (IRIB), Rouen, France
| | - Marie-Laure Walet-Balieu
- Normandie Univ, UNIROUEN, Rouen Proteomic Platform (PISSARO), Institute for Research and Innovation in Biomedicine (IRIB), Rouen, France
| | - Thierry Lecroq
- Normandie Univ, UNIROUEN, LITIS EA 4108, Information Processing in Biology & Health, Rouen, France
| | - Arnaud Lefebvre
- Normandie Univ, UNIROUEN, LITIS EA 4108, Information Processing in Biology & Health, Rouen, France
| | | | - David Vaudry
- Normandie Univ, UNIROUEN, Inserm, Laboratory of Neuronal and Neuroendocrine Communication and Differentiation, Neuropeptides, Neuronal Death and Cell Plasticity Team, Rouen, France.,Normandie Univ, UNIROUEN, Regional Cell Imaging Platform of Normandy (PRIMACEN), Rouen, France.,Normandie Univ, UNIROUEN, Rouen Proteomic Platform (PISSARO), Institute for Research and Innovation in Biomedicine (IRIB), Rouen, France
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9
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Duncan KD, Lanekoff I. Spatially Defined Surface Sampling Capillary Electrophoresis Mass Spectrometry. Anal Chem 2019; 91:7819-7827. [DOI: 10.1021/acs.analchem.9b01516] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Kyle D. Duncan
- Department of Chemistry-BMC, Uppsala University, Uppsala 751 24, Sweden
| | - Ingela Lanekoff
- Department of Chemistry-BMC, Uppsala University, Uppsala 751 24, Sweden
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10
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Neagu AN. Proteome Imaging: From Classic to Modern Mass Spectrometry-Based Molecular Histology. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1140:55-98. [PMID: 31347042 DOI: 10.1007/978-3-030-15950-4_4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
In order to overcome the limitations of classic imaging in Histology during the actually era of multiomics, the multi-color "molecular microscope" by its emerging "molecular pictures" offers quantitative and spatial information about thousands of molecular profiles without labeling of potential targets. Healthy and diseased human tissues, as well as those of diverse invertebrate and vertebrate animal models, including genetically engineered species and cultured cells, can be easily analyzed by histology-directed MALDI imaging mass spectrometry. The aims of this review are to discuss a range of proteomic information emerging from MALDI mass spectrometry imaging comparative to classic histology, histochemistry and immunohistochemistry, with applications in biology and medicine, concerning the detection and distribution of structural proteins and biological active molecules, such as antimicrobial peptides and proteins, allergens, neurotransmitters and hormones, enzymes, growth factors, toxins and others. The molecular imaging is very well suited for discovery and validation of candidate protein biomarkers in neuroproteomics, oncoproteomics, aging and age-related diseases, parasitoproteomics, forensic, and ecotoxicology. Additionally, in situ proteome imaging may help to elucidate the physiological and pathological mechanisms involved in developmental biology, reproductive research, amyloidogenesis, tumorigenesis, wound healing, neural network regeneration, matrix mineralization, apoptosis and oxidative stress, pain tolerance, cell cycle and transformation under oncogenic stress, tumor heterogeneity, behavior and aggressiveness, drugs bioaccumulation and biotransformation, organism's reaction against environmental penetrating xenobiotics, immune signaling, assessment of integrity and functionality of tissue barriers, behavioral biology, and molecular origins of diseases. MALDI MSI is certainly a valuable tool for personalized medicine and "Eco-Evo-Devo" integrative biology in the current context of global environmental challenges.
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Affiliation(s)
- Anca-Narcisa Neagu
- Laboratory of Animal Histology, Faculty of Biology, "Alexandru Ioan Cuza" University of Iasi, Iasi, Romania.
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11
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Duncan KD, Lanekoff I. Oversampling To Improve Spatial Resolution for Liquid Extraction Mass Spectrometry Imaging. Anal Chem 2018; 90:2451-2455. [PMID: 29373011 DOI: 10.1021/acs.analchem.7b04687] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Liquid extraction mass spectrometry imaging (MSI) experiments provide users with direct analysis of biological surfaces with minimal sample preparation. Until now, much of the effort to increase spatial resolution for MSI with liquid extraction techniques has focused on reducing the size of the sampling area. However, this can be experimentally challenging. Here, we present oversampling as a simple alternative to increase the spatial resolution using nanospray desorption electrospray ionization (nano-DESI) MSI. By imaging partial rat spinal cord tissue sections, two major concerns with oversampling are addressed: whether endogenous molecules are significantly depleted from repeated sampling events and whether analytes are redistributed as a result of oversampling. In depth examination of ion images for representative analytes show that depletion and redistribution do not affect analyte localization in the tissue sample. Nano-DESI MSI experiments using three times oversampling provided higher spatial resolution, allowing the observation of features not visible with undersampling. Although proper care must be taken to ensure that oversampling will work in specific applications, we envision oversampling as a simple approach to increase image quality for liquid extraction MSI techniques.
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Affiliation(s)
- Kyle D Duncan
- Department of Chemistry-BMC, Uppsala University , Uppsala, Sweden
| | - Ingela Lanekoff
- Department of Chemistry-BMC, Uppsala University , Uppsala, Sweden
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