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Abstract
Together, loss- and gain-of-function experiments have identified the bone-derived secreted molecule osteocalcin as a hormone with a broad reach in rodents and primates. Following its binding to one of three receptors, osteocalcin exerts a profound influence on various aspects of energy metabolism as well as steroidogenesis, neurotransmitter biosynthesis and thereby male fertility, electrolyte homeostasis, cognition, the acute stress response, and exercise capacity. Although this review focuses mostly on the regulation of energy metabolism by osteocalcin, it also touches on its other functions. Lastly, it proposes what could be a common theme between the functions of osteocalcin and between these functions and the structural functions of bone.
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Affiliation(s)
- Gerard Karsenty
- Departments of Genetics and Development, Vagelos College of Physicians & Surgeons, Columbia University, New York, New York, USA;
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Monteiro CJ, Heery DM, Whitchurch JB. Modern Approaches to Mouse Genome Editing Using the CRISPR-Cas Toolbox and Their Applications in Functional Genomics and Translational Research. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1429:13-40. [PMID: 37486514 DOI: 10.1007/978-3-031-33325-5_2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/25/2023]
Abstract
Mice have been used in biological research for over a century, and their immense contribution to scientific breakthroughs can be seen across all research disciplines, with some of the main beneficiaries being the fields of medicine and life sciences. Genetically engineered mouse models (GEMMs), along with other model organisms, are fundamentally important research tools frequently utilised to enhance our understanding of pathophysiology and biological mechanisms behind disease. In the 1980s, it became possible to precisely edit the mouse genome to create gene knockout and knock-in mice, although with low efficacy. Recent advances utilising CRISPR-Cas technologies have considerably improved our ability to do this with ease and precision, while also allowing the generation of desired genetic variants from single nucleotide substitutions to large insertions/deletions. It is now quick and relatively easy to genetically edit somatic cells which were previously more recalcitrant to traditional approaches. Further refinements have created a 'CRISPR toolkit' that has expanded the use of CRISPR-Cas beyond gene knock-ins and knockouts. In this chapter, we review some of the latest applications of CRISPR-Cas technologies in GEMMs, including nuclease-dead Cas9 systems for activation or repression of gene expression, base editing and prime editing. We also discuss improvements in Cas9 specificity, targeting efficacy and delivery methods in mice. Throughout, we provide examples wherein CRISPR-Cas technologies have been applied to target clinically relevant genes in preclinical GEMMs, both to generate humanised models and for experimental gene therapy research.
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Affiliation(s)
- Cintia J Monteiro
- Department of Genetics, Molecular Immunogenetics Group, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - David M Heery
- School of Pharmacy, University of Nottingham, Nottingham, UK
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Berger JM, Karsenty G. Osteocalcin and the Physiology of Danger. FEBS Lett 2021; 596:665-680. [PMID: 34913486 PMCID: PMC9020278 DOI: 10.1002/1873-3468.14259] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Revised: 11/29/2021] [Accepted: 12/07/2021] [Indexed: 12/02/2022]
Abstract
Bone biology has long been driven by the question as to what molecules affect cell differentiation or the functions of bone. Exploring this issue has been an extraordinarily powerful way to improve our knowledge of bone development and physiology. More recently, a second question has emerged: does bone have other functions besides making bone? Addressing this conundrum revealed that the bone-derived hormone osteocalcin affects a surprisingly large number of organs and physiological processes, including acute stress response. This review will focus on this emerging aspect of bone biology taking osteocalcin as a case study and will show how classical and endocrine functions of bone help to define a new functional identity for this tissue.
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Affiliation(s)
- Julian Meyer Berger
- Department of Genetics and Development, Vagelos College of Physicians and Surgeons, Columbia University, NY, 10032, USA
| | - Gerard Karsenty
- Department of Genetics and Development, Vagelos College of Physicians and Surgeons, Columbia University, NY, 10032, USA
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Yadav VK, Berger JM, Singh P, Nagarajan P, Karsenty G. Embryonic osteocalcin signalling determines lifelong adrenal steroidogenesis and homeostasis in the mouse. J Clin Invest 2021; 132:153752. [PMID: 34905510 PMCID: PMC8843753 DOI: 10.1172/jci153752] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 11/30/2021] [Indexed: 11/17/2022] Open
Abstract
Through their ability to regulate gene expression in most organs, glucocorticoid hormones influence numerous physiological processes and therefore are key regulators of organismal homeostasis. In bone, glucocorticoid hormones inhibit the expression of the hormone Osteocalcin for poorly understood reasons. Here we show that in a classical endocrine feedback loop, osteocalcin in return enhances the biosynthesis of glucocorticoid but also mineralocorticoid hormones (adrenal steroidogenesis) in rodents and primates. Conversely, inactivating osteocalcin signalling in adrenal glands significantly impairs adrenal growth and steroidogenesis in mice. Embryo-made osteocalcin is necessary for normal Sf1 expression in foetal adrenal cells and adrenal cell steroidogenic differentiation, it therefore determines the number of steroidogenic cells present in adrenal glands of adult animals. Embryonic not postnatal osteocalcin also governs adrenal growth, adrenal steroidogenesis, blood pressure, electrolyte equilibrium and the rise of circulating corticosterone during the acute stress response in adult offspring. This osteocalcin-dependent regulation of adrenal development and steroidogenesis occurs even in the absence of a functional of hypothalamus-pituitary-adrenal axis; this explains why osteocalcin administration during pregnancy promotes adrenal growth and steroidogenesis and improves survival of adrenocorticotropic hormone signalling-deficient animals. This study reveals that a bone-derived, embryonic hormone influences lifelong adrenal functions and organismal homeostasis in the mouse.
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Affiliation(s)
- Vijay K Yadav
- Department of Genetics and Development, Columbia University, New York, United States of America
| | - Julian M Berger
- Department of Genetics and Development, Columbia University, New York, United States of America
| | - Parminder Singh
- Metabolic Research Laboratory, National Institute of Immunology, New Delhi, India
| | - Perumal Nagarajan
- Experimental Animal Facility, National Institute of Immunology, New Delhi, India
| | - Gerard Karsenty
- Department of Genetics and Development, Columbia University, New York, United States of America
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Jaschke N, Sipos W, Hofbauer LC, Rachner TD, Rauner M. Skeletal endocrinology: where evolutionary advantage meets disease. Bone Res 2021; 9:28. [PMID: 34050126 PMCID: PMC8163738 DOI: 10.1038/s41413-021-00149-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 02/16/2021] [Accepted: 02/23/2021] [Indexed: 02/06/2023] Open
Abstract
The regulation of whole-body homeostasis by the skeleton is mediated by its capacity to secrete endocrine signaling molecules. Although bone-derived hormones confer several adaptive benefits, their physiological functions also involve trade-offs, thus eventually contributing to disease. In this manuscript, we discuss the origins and functions of two of the best-studied skeletal mediators, fibroblast growth factor 23 and osteocalcin, in an evolutionary context. Moreover, we provide a theoretical framework seeking to explain the broad involvement of these two hormones in amniote physiology as well as their potential to fuel the development and progression of diseases. Vice versa, we outline which perturbations might be amenable to manipulation of these systems and discuss limitations and ongoing challenges in skeletal endocrine research. Finally, we summarize unresolved questions and potential future studies in this thriving field.
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Affiliation(s)
- Nikolai Jaschke
- Department of Medicine III & Center for Healthy Aging, Technische Universität Dresden, Dresden, Germany
| | - Wolfgang Sipos
- Clinical Department for Farm Animals, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Lorenz C Hofbauer
- Department of Medicine III & Center for Healthy Aging, Technische Universität Dresden, Dresden, Germany
| | - Tilman D Rachner
- Department of Medicine III & Center for Healthy Aging, Technische Universität Dresden, Dresden, Germany
| | - Martina Rauner
- Department of Medicine III & Center for Healthy Aging, Technische Universität Dresden, Dresden, Germany.
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Soave M, Stoddart LA, White CW, Kilpatrick LE, Goulding J, Briddon SJ, Hill SJ. Detection of genome-edited and endogenously expressed G protein-coupled receptors. FEBS J 2021; 288:2585-2601. [PMID: 33506623 PMCID: PMC8647918 DOI: 10.1111/febs.15729] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 01/20/2021] [Accepted: 01/25/2021] [Indexed: 12/11/2022]
Abstract
G protein-coupled receptors (GPCRs) are the largest family of membrane receptors and major targets for FDA-approved drugs. The ability to quantify GPCR expression and ligand binding characteristics in different cell types and tissues is therefore important for drug discovery. The advent of genome editing along with developments in fluorescent ligand design offers exciting new possibilities to probe GPCRs in their native environment. This review provides an overview of the recent technical advances employed to study the localisation and ligand binding characteristics of genome-edited and endogenously expressed GPCRs.
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Affiliation(s)
- Mark Soave
- Division of Physiology, Pharmacology and NeuroscienceSchool of Life SciencesUniversity of NottinghamUK
- Centre of Membrane Proteins and Receptors (COMPARE)University of Birmingham and University of NottinghamThe MidlandsUK
| | - Leigh A. Stoddart
- Division of Physiology, Pharmacology and NeuroscienceSchool of Life SciencesUniversity of NottinghamUK
- Centre of Membrane Proteins and Receptors (COMPARE)University of Birmingham and University of NottinghamThe MidlandsUK
| | - Carl W. White
- Centre of Membrane Proteins and Receptors (COMPARE)University of Birmingham and University of NottinghamThe MidlandsUK
- Harry Perkins Institute of Medical Research and Centre for Medical ResearchQEII Medical CentreThe University of Western AustraliaNedlandsAustralia
- Australian Research Council Centre for Personalised Therapeutics TechnologiesAustralia
| | - Laura E. Kilpatrick
- Centre of Membrane Proteins and Receptors (COMPARE)University of Birmingham and University of NottinghamThe MidlandsUK
- Division of Biomolecular Science and Medicinal ChemistrySchool of Pharmacy, Biodiscovery InstituteUniversity of NottinghamUK
| | - Joëlle Goulding
- Division of Physiology, Pharmacology and NeuroscienceSchool of Life SciencesUniversity of NottinghamUK
- Centre of Membrane Proteins and Receptors (COMPARE)University of Birmingham and University of NottinghamThe MidlandsUK
| | - Stephen J. Briddon
- Division of Physiology, Pharmacology and NeuroscienceSchool of Life SciencesUniversity of NottinghamUK
- Centre of Membrane Proteins and Receptors (COMPARE)University of Birmingham and University of NottinghamThe MidlandsUK
| | - Stephen J. Hill
- Division of Physiology, Pharmacology and NeuroscienceSchool of Life SciencesUniversity of NottinghamUK
- Centre of Membrane Proteins and Receptors (COMPARE)University of Birmingham and University of NottinghamThe MidlandsUK
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Pi M, Nishimoto SK, Darryl Quarles L. Explaining Divergent Observations Regarding Osteocalcin/GPRC6A Endocrine Signaling. Endocrinology 2021; 162:6104945. [PMID: 33474566 PMCID: PMC7880225 DOI: 10.1210/endocr/bqab011] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Indexed: 12/13/2022]
Abstract
A new schema proposes that the bone-derived osteocalcin (Ocn) peptide hormone activates the G-protein-coupled receptor GPRC6A to directly regulate glucose and fat metabolism in liver, muscle, and fat, and to stimulate the release of metabolism-regulating hormones, including insulin, fibroblast growth factor 21, glucagon-like peptide 1, testosterone, and interleukin 6. Ocn/GPRC6A activation has also been implicated in cancer progression. GPRC6A is activated by cations, amino acids, and testosterone. The multiligand specificity, the regulation of energy metabolism in diverse tissues, and the coordinated release of metabolically active hormones make the GPRC6A endocrine networks unique. Recently, the significance of Ocn/GPRCA has been questioned. There is a lack of metabolic abnormalities in newly created genetically engineered Ocn- and Gprc6a-deficient mouse models. There are also paradoxical observations that GPRC6A may function as a tumor suppressor. In addition, discordant published studies have cast doubt on the function of the most prevalent uniquely human GPRC6A-KGKY polymorphism. Explanations for these divergent findings are elusive. We provide evidence that the metabolic susceptibility of genetically engineered Ocn- and Gprc6a-deficient mice is influenced by environmental challenges and genetic differences in mouse strains. In addition, the GPRC6A-KGKY polymorphism appears to be a gain-of-function variant. Finally, alternatively spliced isoforms of GPRC6A may alter ligand specificity and signaling that modulate oncogenic effects. Thus, genetic, post-translational and environmental factors likely account for the variable results regarding the functions of GPRC6A in animal models. Pending additional information, GPRC6A should remain a potential therapeutic target for regulating energy and fat metabolism, hormone production, and cancer progression.
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Affiliation(s)
- Min Pi
- Department of Medicine, University of Tennessee Health Science Center, Memphis, TN, USA
| | - Satoru Kenneth Nishimoto
- Department of Microbiology, Immunology & Biochemistry, University of Tennessee Health Science Center, Memphis, TN, USA
| | - L Darryl Quarles
- Department of Medicine, University of Tennessee Health Science Center, Memphis, TN, USA
- Correspondence: L. Darryl Quarles, MD, University of Tennessee Health Sciences Center, Memphis, TN, USA. . Current Affiliation: 965 Court Ave, Suite B226, Memphis, TN 38163, USA
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Tacey A, Hayes A, Zulli A, Levinger I. Osteocalcin and vascular function: is there a cross-talk? Mol Metab 2021; 49:101205. [PMID: 33684607 PMCID: PMC8027272 DOI: 10.1016/j.molmet.2021.101205] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 02/22/2021] [Accepted: 03/03/2021] [Indexed: 01/05/2023] Open
Abstract
Background The bone-derived protein osteocalcin (OC), in its undercarboxylated (ucOC) form, has a beneficial effect on energy metabolism and may be a future therapeutic target for metabolic diseases. Increasing evidence suggests a link between ucOC and cardiovascular disease (CVD) development; however, the exact relationship is conflicting and unclear. Scope of review The aim of this review was to summarise the current research examining the interaction between OC and vascular dysfunction, the initiating stage in the development of atherosclerosis and CVD. Major conclusions In humans, the association between OC and vascular function is inconsistent. Several studies report that total OC (tOC) is associated with adverse function or beneficial function, whereas others report that tOC and ucOC has no effect on vascular function. The conflicting data are likely due to several methodological inconsistencies, in particular the lack of studies reporting circulating ucOC levels. In animal models, the direct administration of ucOC to isolated blood vessels ex vivo produced minimal changes in endothelial function, but importantly, no adverse responses. Finally, in human endothelial and vascular smooth muscle cells, ucOC treatment did not influence classical markers of cellular function, including endothelin-1, vascular adhesion molecule-1 and monocyte chemoattractant protein-1 after exposure to high glucose and inflammatory conditions. The lack of adverse effects in ex vivo and in vitro studies suggests that ucOC may be targeted as a future therapeutic for metabolic diseases, without the risk of detrimental effects in the vasculature. However, further studies are needed to confirm these findings and to investigate whether there is a direct beneficial influence of ucOC. ucOC is implicated in the regulation of glucose homeostasis; but its role in the vasculature has been minimally reported. Studies which examine the association between ucOC and vascular function in humans often report inconsistent outcomes. In addition, ex vivo and in vitro studies have reported that ucOC likely does not directly regulate endothelial function. ucOC may be targeted as a therapeutic treatment for metabolic diseases without a risk of adverse effects in the vasculature.
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Affiliation(s)
- Alexander Tacey
- Institute for Health and Sport (IHES), Victoria University, Melbourne, VIC, Australia; Australian Institute for Musculoskeletal Science (AIMSS), The University of Melbourne and Western Health, St Albans, VIC, Australia
| | - Alan Hayes
- Institute for Health and Sport (IHES), Victoria University, Melbourne, VIC, Australia; Australian Institute for Musculoskeletal Science (AIMSS), The University of Melbourne and Western Health, St Albans, VIC, Australia
| | - Anthony Zulli
- Institute for Health and Sport (IHES), Victoria University, Melbourne, VIC, Australia
| | - Itamar Levinger
- Institute for Health and Sport (IHES), Victoria University, Melbourne, VIC, Australia; Australian Institute for Musculoskeletal Science (AIMSS), The University of Melbourne and Western Health, St Albans, VIC, Australia.
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Wang JS, Mazur CM, Wein MN. Sclerostin and Osteocalcin: Candidate Bone-Produced Hormones. Front Endocrinol (Lausanne) 2021; 12:584147. [PMID: 33776907 PMCID: PMC7988212 DOI: 10.3389/fendo.2021.584147] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Accepted: 01/13/2021] [Indexed: 12/22/2022] Open
Abstract
In addition to its structural role, the skeleton serves as an endocrine organ that controls mineral metabolism and energy homeostasis. Three major cell types in bone - osteoblasts, osteoclasts, and osteocytes - dynamically form and maintain bone and secrete factors with systemic activity. Osteocalcin, an osteoblast-derived factor initially described as a matrix protein that regulates bone mineralization, has been suggested to be an osteoblast-derived endocrine hormone that regulates multiple target organs including pancreas, liver, muscle, adipose, testes, and the central and peripheral nervous system. Sclerostin is predominantly produced by osteocytes, and is best known as a paracrine-acting regulator of WNT signaling and activity of osteoblasts and osteoclasts on bone surfaces. In addition to this important paracrine role for sclerostin within bone, sclerostin protein has been noted to act at a distance to regulate adipocytes, energy homeostasis, and mineral metabolism in the kidney. In this article, we aim to bring together evidence supporting an endocrine function for sclerostin and osteocalcin, and discuss recent controversies regarding the proposed role of osteocalcin outside of bone. We summarize the current state of knowledge on animal models and human physiology related to the multiple functions of these bone-derived factors. Finally, we highlight areas in which future research is expected to yield additional insights into the biology of osteocalcin and sclerostin.
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Affiliation(s)
- Jialiang S. Wang
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States
| | - Courtney M. Mazur
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States
| | - Marc N. Wein
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States
- Broad Institute of Massachusetts Institute of Technology (MIT) and Harvard, Cambridge, MA, United States
- Harvard Stem Cell Institute, Cambridge, MA, United States
- *Correspondence: Marc N. Wein,
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McEwan AR, MacKenzie A. Perspective: Quality Versus Quantity; Is It Important to Assess the Role of Enhancers in Complex Disease from an In Vivo Perspective? Int J Mol Sci 2020; 21:E7856. [PMID: 33113946 PMCID: PMC7660172 DOI: 10.3390/ijms21217856] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 10/15/2020] [Accepted: 10/20/2020] [Indexed: 12/18/2022] Open
Abstract
Sequencing of the human genome has permitted the development of genome-wide association studies (GWAS) to analyze the genetics of a number of complex disorders such as depression, anxiety and substance abuse. Thanks to their ability to analyze huge cohort sizes, these studies have successfully identified thousands of loci associated with a broad spectrum of complex diseases. Disconcertingly, the majority of these GWAS hits occur in non-coding regions of the genome, much of which controls the cell-type-specific expression of genes essential to health. In contrast to gene coding sequences, it is a challenge to understand the function of this non-coding regulatory genome using conventional biochemical techniques in cell lines. The current commentary scrutinizes the field of complex genetics from the standpoint of the large-scale whole-genome functional analysis of the promoters and cis-regulatory elements using chromatin markers. We contrast these large scale quantitative techniques against comparative genomics and in vivo analyses including CRISPR/CAS9 genome editing to determine the functional characteristics of these elements and to understand how polymorphic variation and epigenetic changes within these elements might contribute to complex disease and drug response. Most importantly, we suggest that, although the role of chromatin markers will continue to be important in identifying and characterizing enhancers, more emphasis must be placed on their analysis in relevant in-vivo models that take account of the appropriate cell-type-specific roles of these elements. It is hoped that offering these insights might refocus progress in analyzing the data tsunami of non-coding GWAS and whole-genome sequencing "hits" that threatens to overwhelm progress in the field.
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Affiliation(s)
| | - Alasdair MacKenzie
- School of Medicine, Medical Sciences and Nutrition, Institute of Medical Sciences, Foresterhill, University of Aberdeen, Aberdeen AB25 2ZD, UK;
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