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Athavale ON, Di Natale MR, Avci R, Clark AR, Furness JB, Cheng LK, Du P. Mapping the rat gastric slow-wave conduction pathway: bridging in vitro and in vivo methods, revealing a loosely coupled region in the distal stomach. Am J Physiol Gastrointest Liver Physiol 2024; 327:G254-G266. [PMID: 38860855 PMCID: PMC11427108 DOI: 10.1152/ajpgi.00069.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2024] [Revised: 06/04/2024] [Accepted: 06/10/2024] [Indexed: 06/12/2024]
Abstract
Rhythmic electrical events, termed slow waves, govern the timing and amplitude of phasic contractions of the gastric musculature. Extracellular multielectrode measurement of gastric slow waves can be a biomarker for phenotypes of motility dysfunction. However, a gastric slow-wave conduction pathway for the rat, a common animal model, is unestablished. In this study, the validity of extracellular recording was demonstrated in vitro with simultaneous intracellular and extracellular recordings and by pharmacological inhibition of slow waves. The conduction pathway was determined by in vivo extracellular recordings while considering the effect of motion. Slow-wave characteristics [means (SD)] varied regionally having higher amplitude in the antrum than the distal corpus [1.03 (0.12) mV vs. 0.75 (0.31) mV; n = 7; P = 0.025 paired t test] and faster propagation near the greater curvature than the lesser curvature [1.00 (0.14) mm·s-1 vs. 0.74 (0.14) mm·s-1; n = 9 GC, 7 LC; P = 0.003 unpaired t test]. Notably, in some subjects, separate wavefronts propagated near the lesser and greater curvatures with a loosely coupled region occurring in the area near the distal corpus midline at the interface of the two wavefronts. This region had either the greater or lesser curvature wavefront propagating through it in a time-varying manner. The conduction pattern suggests that slow waves in the rat stomach form annular wavefronts in the antrum and not the corpus. This study has implications for interpretation of the relationship between slow waves, the interstitial cells of Cajal network structure, smooth muscles, and gastric motility.NEW & NOTEWORTHY Mapping of rat gastric slow waves showed regional variations in their organization. In some subjects, separate wavefronts propagated near the lesser and greater curvatures with a loosely coupled region near the midline, between the wavefronts, having a varying slow-wave origin. Furthermore, simultaneous intracellular and extracellular recordings were concordant and independent of movement artifacts, indicating that extracellular recordings can be interpreted in terms of their intracellular counterparts when intracellular recording is not possible.
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Affiliation(s)
- Omkar N Athavale
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Madeleine R Di Natale
- Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia
- Department of Anatomy & Physiology, University of Melbourne, Parkville, Victoria, Australia
| | - Recep Avci
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Alys R Clark
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - John B Furness
- Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia
- Department of Anatomy & Physiology, University of Melbourne, Parkville, Victoria, Australia
| | - Leo K Cheng
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Peng Du
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
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2
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Milan AM, Menting GGA, Barnett MPG, Liu Y, McNabb WC, Roy NC, Hutchings SC, Mungure T, Weeks M, Li S, Hort J, Calder S, O'Grady G, Mithen RF. The impact of heat-set milk protein gel textures modified by pH on circulating amino acid appearance and gastric function in healthy female adults: a randomised controlled trial. Food Funct 2024; 15:5613-5626. [PMID: 38722062 DOI: 10.1039/d3fo04474b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/21/2024]
Abstract
Modification of dairy proteins during processing impacts structural assemblies, influencing textural and nutritional properties of dairy products, and release and availability of amino acids during digestion. By modifying only pH, acid heat-set bovine dairy gels with divergent textural properties were developed to alter protein digestion. In vitro assay confirmed faster digestion of protein from a firm gel (pH 5.65) versus a soft gel (pH 6.55). We hypothesised that firm gel (FIRM-G; pH 5.6) would result in greater indispensable amino acid (IAA) appearance in circulation over 5 h and corresponding differences in gastric myoelectrical activity relative to soft gel (SOFT-G; pH 6.2). In a randomised, single-blind cross-over trial, healthy females (n = 20) consumed 150 g of each gel; plasma amino acid appearance was assessed over 5 hours. Iso-nitrogenous, iso-caloric gels were prepared from identical mixtures of bovine milk and whey protein concentrates; providing 17.7 g (FIRM-G) and 18.9 g (SOFT-G) of protein per serving. Secondary outcomes included gastric myoelectrical activity measured by body surface gastric mapping, glycaemic, triglyceridaemic, and subjective appetite and digestive responses. Overall plasma IAA (area under the curve) did not differ between gels. However, plasma IAA concentrations were higher, and increased more rapidly over time after SOFT-G compared with FIRM-G (1455 ± 53 versus 1350 ± 62 μmol L-1 at 30 min, p = 0.024). Similarly, total, branched-chain and dispensable amino acids were higher at 30 min with SOFT-G than FIRM-G (total: 3939 ± 97 versus 3702 ± 127 μmol L-1, p = 0.014; branched-chain: 677 ± 30 versus 619 ± 34 μmol L-1, p = 0.047; dispensable: 2334 ± 53 versus 2210 ± 76 μmol L-1, p = 0.032). All other measured parameters were similar between gels. Peak postprandial aminoacidaemia was higher and faster following ingestion of SOFT-G. Customised plasma amino acid appearance from dairy is achievable by altering gel coagulum structure using pH during processing and may have minimal influence on related postprandial responses, with implications for targeting food design for optimal health. The Clinical Trial Registry number is ACTRN12622001418763 (https://www.anzctr.org.au) registered November 7, 2022.
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Affiliation(s)
- Amber M Milan
- The Liggins Institute, The University of Auckland, Auckland, New Zealand.
- AgResearch Limited, Palmerston North, New Zealand.
- The High-Value Nutrition National Science Challenge, Auckland, New Zealand
| | | | - Matthew P G Barnett
- AgResearch Limited, Palmerston North, New Zealand.
- The Riddet Institute, Palmerston North, New Zealand.
| | - Yutong Liu
- The Liggins Institute, The University of Auckland, Auckland, New Zealand.
| | - Warren C McNabb
- The High-Value Nutrition National Science Challenge, Auckland, New Zealand
- The Riddet Institute, Palmerston North, New Zealand.
| | - Nicole C Roy
- The High-Value Nutrition National Science Challenge, Auckland, New Zealand
- The Riddet Institute, Palmerston North, New Zealand.
- Department of Human Nutrition, The University of Otago, Otago, New Zealand.
| | | | - Tanyaradzwa Mungure
- AgResearch Limited, Palmerston North, New Zealand.
- The University of Melbourne, Melbourne, Australia.
| | - Mike Weeks
- AgResearch Limited, Palmerston North, New Zealand.
| | - Siqi Li
- The Riddet Institute, Palmerston North, New Zealand.
| | - Joanne Hort
- The Riddet Institute, Palmerston North, New Zealand.
- Food Experience and Sensory Testing Lab, Massey University, Palmerston North, New Zealand.
| | - Stefan Calder
- Department of Surgery, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand.
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | - Greg O'Grady
- Department of Surgery, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand.
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | - Richard F Mithen
- The Liggins Institute, The University of Auckland, Auckland, New Zealand.
- The High-Value Nutrition National Science Challenge, Auckland, New Zealand
- The Riddet Institute, Palmerston North, New Zealand.
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3
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Bisht A, Goh KKT, Matia-Merino L. The fate of mamaku gum in the gut: effect on in vitro gastrointestinal function and colon fermentation by human faecal microbiota. Food Funct 2023; 14:7024-7039. [PMID: 37439088 DOI: 10.1039/d3fo01665j] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/14/2023]
Abstract
Mamaku is a fern indigenous to the Pacific Islands with a long history of use for therapeutic benefits such as to combat skin conditions and manage gastrointestinal discomfort; however, the scientific understanding is limited. In this study, we examined the effect of mamaku gum, extracted from different age fronds of the New Zealand Black tree fern (Cyathea medullaris, Mamaku) (stage 1: young, stage 2: fully grown and stage 3: old), on gut function using in vitro models of static digestion, enzyme activity and static colonic fermentation. Under simulated gastric and small intestinal conditions, mamaku polysaccharide (MP) was indigestible as there was no decrease in the molecular weight (Mw) of the polymer. Mamaku gum could reduce the activity of digestive enzymes (α-amylase, pepsin and lipase) in a concentration-dependent manner, with the stage 1 sample showing the highest inhibition and stage 3 the lowest. All three mamaku gum samples could also equally bind bile acids during intestinal digestion. During fermentation, human faecal microbiota utilised the mamaku gum and significantly increased the production of total short-chain fatty acids (SCFAs) and reduced the pH when compared with the blank. However, changes in SCFAs and pH for mamaku groups were less prominent than for inulin and guar gum control groups, suggesting lower fermentability of mamaku gum compared to the latter two. Furthermore, mamaku gum altered the composition of colonic microbiota, specifically reducing the ratio of Firmicutes to Bacteroidetes and increasing the relative abundance of Bacteroides, Enterococcus, Paraprevotella and Parabacteroides genera. No obvious difference between mamaku gum samples from stage 1, 2 and 3 was observed during fermentation. Collectively, these results suggest that mamaku gum may modulate the functionality of the host gut by reducing enzyme activity, binding bile acids, altering the colonic microbial composition and producing SCFAs.
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Affiliation(s)
- Akshay Bisht
- School of Food and Advanced Technology, Massey University, Palmerston North, New Zealand.
| | - Kelvin K T Goh
- School of Food and Advanced Technology, Massey University, Palmerston North, New Zealand.
| | - Lara Matia-Merino
- School of Food and Advanced Technology, Massey University, Palmerston North, New Zealand.
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Wang X, Cao J, Han K, Choi M, She Y, Scheven UM, Avci R, Du P, Cheng LK, Natale MRD, Furness JB, Liu Z. Diffeomorphic Surface Modeling for MRI-Based Characterization of Gastric Anatomy and Motility. IEEE Trans Biomed Eng 2023; 70:2046-2057. [PMID: 37018592 PMCID: PMC10443119 DOI: 10.1109/tbme.2023.3234509] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
OBJECTIVE Gastrointestinal magnetic resonance imaging (MRI) provides rich spatiotemporal data about the movement of the food inside the stomach, but does not directly report muscular activity on the stomach wall. Here we describe a novel approach to characterize the motility of the stomach wall that drives the volumetric changes of the ingesta. METHODS A neural ordinary differential equation was optimized to model a diffeomorphic flow that ascribed the deformation of the stomach wall to a continuous biomechanical process. Driven by this diffeomorphic flow, the surface of the stomach progressively changes its shape over time, while preserving its topology and manifoldness. RESULTS We tested this approach with MRI data collected from 10 rats under a lightly anesthetized condition, and demonstrated accurate characterization of gastric motor events with an error in the order of sub-millimeters. Uniquely, we characterized gastric anatomy and motility with a surface coordinate system common at both individual and group levels. Functional maps were generated to reveal the spatial, temporal, and spectral characteristics of muscle activity and its coordination across different regions. The peristalsis at the distal antrum had a dominant frequency and peak-to-peak amplitude of [Formula: see text] cycles per minute and [Formula: see text] mm, respectively. The relationship between muscle thickness and gastric motility was found to be distinct between two functional regions in the proximal and distal stomach. CONCLUSION These results demonstrate the efficacy of using MRI to model gastric anatomy and function. SIGNIFICANCE The proposed approach is expected to enable non-invasive and accurate mapping of gastric motility for preclinical and clinical studies.
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Evaluation of Pharmacobezoar Formation from Suspensions of Spray-Dried Amorphous Solid Dispersions: An MRI Study in Rats. Pharmaceutics 2023; 15:pharmaceutics15030887. [PMID: 36986751 PMCID: PMC10052685 DOI: 10.3390/pharmaceutics15030887] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 03/02/2023] [Accepted: 03/07/2023] [Indexed: 03/12/2023] Open
Abstract
Spray-dried amorphous solid dispersions of new chemical entities and pH-dependent soluble polymer hydroxypropyl methylcellulose acetate succinate (HPMC-AS) were found to form solid agglomerates in the gastrointestinal tract of rodents after oral administration. These agglomerates, referring to descriptions of intra-gastrointestinal aggregated oral dosage forms termed pharmacobezoars, represent a potential risk for animal welfare. Previously, we introduced an in vitro model to assess the agglomeration potential of amorphous solid dispersions from suspensions and how it can be reduced. In this work, we investigated if the in vitro effective approach of viscosity enhancement of the vehicle used to prepare suspensions of amorphous solid dispersions could reduce the pharmacobezoar formation potential following repeated daily oral dosing to rats as well. The dose level of 2400 mg/kg/day used in the main study was determined in a dose finding study carried out in advance. In the dose finding study, MRI investigations were carried out at short time intervals to gain insights into the process of pharmacobezoar formation. Whereas MRI investigations underlined the importance of the forestomach for the formation of pharmacobezoars, viscosity enhancement of the vehicle reduced the incidence of pharmacobezoars, delayed the onset of pharmacobezoar formation and reduced the overall mass of pharmacobezoars found at necropsy.
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6
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An In Vitro Model to Investigate the Potential of Solid Dispersions to Form Pharmacobezoars. Pharmaceutics 2022; 14:pharmaceutics14122608. [PMID: 36559103 PMCID: PMC9785156 DOI: 10.3390/pharmaceutics14122608] [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] [Received: 10/31/2022] [Revised: 11/22/2022] [Accepted: 11/23/2022] [Indexed: 11/29/2022] Open
Abstract
The formation of pharmacobezoars from suspensions of spray-dried amorphous solid dispersions (SD-ASDs) of new chemical entities (NCEs) and hydroxypropyl methylcellulose acetate succinate (HPMC-AS) represents a non-compound related adverse effect in preclinical oral toxicity studies in rodents. Whereas the contribution of the insolubility of the carrier polymer to this process taking place in the acidic environment of the rodent stomach is conclusive, unawareness of the extent of in vivo pharmacobezoar formation is adverse. In order to evaluate the risk of pharmacobezoar formation before in vivo administration, we subsequently introduce an in vitro model to assess the agglomeration potential of solid dispersions. To verify that the pharmacobezoar formation potential can be assessed based on the observed agglomeration potential, we conducted a sequence of experiments with two HPMC-AS-based SD-ASD formulations. In vitro, we found their different in vivo pharmacobezoar formation potential reflected by a significantly increased agglomerated mass of formulation 1 per day compared to formulation 2. In order to find an approach to reduce the agglomeration potential of solid dispersion from suspensions, we further applied the model to investigate the impact of the viscosity of the vehicle used to prepare suspensions on agglomerate formation.
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7
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Di Natale MR, Patten L, Molero JC, Stebbing MJ, Hunne B, Wang X, Liu Z, Furness JB. Organisation of the musculature of the rat stomach. J Anat 2022; 240:711-723. [PMID: 34747011 PMCID: PMC8930815 DOI: 10.1111/joa.13587] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 10/26/2021] [Accepted: 10/27/2021] [Indexed: 01/02/2023] Open
Abstract
The strengths, directions and coupling of the movements of the stomach depend on the organisation of its musculature. Although the rat has been used as a model species to study gastric function, there is no detailed, quantitative study of the arrangement of the gastric muscles in rat. Here we provide a descriptive and quantitative account, and compare it with human gastric anatomy. The rat stomach has three components of the muscularis externa, a longitudinal coat, a circular coat and an internal oblique (sling) muscle in the region of the gastro-oesophageal junction. These layers are similar to human. Unlike human, the rat stomach is also equipped with paired muscular oesophago-pyloric ligaments that lie external to the longitudinal muscle. There is a prominent muscularis mucosae throughout the stomach and strands of smooth muscle occur in the mucosa, between the glands of the corpus and antrum. The striated muscle of the oesophageal wall reaches to the stomach, unlike the human, in which the wall of the distal oesophagus is smooth muscle. Thus, the continuity of gastric and oesophageal smooth muscle bundles, that occurs in human, does not occur in rat. Circular muscle bundles extend around the circumference of the stomach, in the fundus forming a cap of parallel muscle bundles. This arrangement favours co-ordinated circumferential contractions. Small bands of muscle make connections between the circular muscle bundles. This is consistent with a slower conduction of excitation orthogonal to the circular muscle bundles, across the corpus towards the distal antrum. The oblique muscle merged and became continuous with the circular muscle close to the gastro-oesophageal junction at the base of the fundus, and in the corpus, lateral to the lesser curvature. Quantitation of muscle thickness revealed gradients of thickness of both the longitudinal and circular muscle. This anatomical study provides essential data for interpreting gastric movements.
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Affiliation(s)
- Madeleine R. Di Natale
- Department of Anatomy & PhysiologyUniversity of MelbourneParkvilleVictoriaAustralia
- Florey Institute of Neuroscience and Mental HealthParkvilleVictoriaAustralia
| | - Lauren Patten
- Florey Institute of Neuroscience and Mental HealthParkvilleVictoriaAustralia
| | - Juan C. Molero
- Department of Anatomy & PhysiologyUniversity of MelbourneParkvilleVictoriaAustralia
- Florey Institute of Neuroscience and Mental HealthParkvilleVictoriaAustralia
| | - Martin J. Stebbing
- Department of Anatomy & PhysiologyUniversity of MelbourneParkvilleVictoriaAustralia
- Florey Institute of Neuroscience and Mental HealthParkvilleVictoriaAustralia
| | - Billie Hunne
- Department of Anatomy & PhysiologyUniversity of MelbourneParkvilleVictoriaAustralia
| | - Xiaokai Wang
- Department of Biomedical EngineeringUniversity of MichiganAnn ArborMichiganUSA
| | - Zhongming Liu
- Department of Biomedical EngineeringUniversity of MichiganAnn ArborMichiganUSA
| | - John B. Furness
- Department of Anatomy & PhysiologyUniversity of MelbourneParkvilleVictoriaAustralia
- Florey Institute of Neuroscience and Mental HealthParkvilleVictoriaAustralia
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8
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Costa M, Wiklendt L, Hibberd T, Dinning P, Spencer NJ, Brookes S. Analysis of Intestinal Movements with Spatiotemporal Maps: Beyond Anatomy and Physiology. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2022; 1383:271-294. [PMID: 36587166 DOI: 10.1007/978-3-031-05843-1_26] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Over 150 years ago, methods for quantitative analysis of gastrointestinal motor patterns first appeared. Graphic representations of physiological variables were recorded with the kymograph after the mid-1800s. Changes in force or length of intestinal muscles could be quantified, however most recordings were limited to a single point along the digestive tract.In parallel, photography and cinematography with X-Rays visualised changes in intestinal shape, but were hard to quantify. More recently, the ability to record physiological events at many sites along the gut in combination with computer processing allowed construction of spatiotemporal maps. These included diameter maps (DMaps), constructed from video recordings of intestinal movements and pressure maps (PMaps), constructed using data from high-resolution manometry catheters. Combining different kinds of spatiotemporal maps revealed additional details about gut wall status, including compliance, which relates forces to changes in length. Plotting compliance values along the intestine enabled combined DPMaps to be constructed, which can distinguish active contractions and relaxations from passive changes. From combinations of spatiotemporal maps, it is possible to deduce the role of enteric circuits and pacemaker cells in the generation of complex motor patterns. Development and application of spatiotemporal methods to normal and abnormal motor patterns in animals and humans is ongoing, with further technical improvements arising from their combination with impedance manometry, magnetic resonance imaging, electrophysiology, and ultrasonography.
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Affiliation(s)
- Marcello Costa
- College of Medicine and Public Health, Department of Human Physiology, Flinders University, Bedford Park, SA, Australia.
| | - Luke Wiklendt
- Department of Gastroenterology and Surgery, Flinders Medical Centre, Bedford Park, SA, Australia
| | - Tim Hibberd
- College of Medicine and Public Health, Department of Human Physiology, Flinders University, Bedford Park, SA, Australia
| | - Phil Dinning
- Department of Gastroenterology and Surgery, Flinders Medical Centre, Bedford Park, SA, Australia
| | - Nick J Spencer
- College of Medicine and Public Health, Department of Human Physiology, Flinders University, Bedford Park, SA, Australia
| | - Simon Brookes
- College of Medicine and Public Health, Department of Human Physiology, Flinders University, Bedford Park, SA, Australia
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10
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Lentle RG. Deconstructing the physical processes of digestion: reductionist approaches may provide greater understanding. Food Funct 2018; 9:4069-4084. [PMID: 30011345 DOI: 10.1039/c8fo00722e] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
I provide a broad overview of the physical factors that govern intestinal digestion i.e. the admixture of food particles in digesta with secreted enzymes and the subsequent mass transfer of liberated nutrients from the surfaces of particles to the gut wall, with a view to outlining the quantitative work that is required to determine the relative importance of these factors in the digestion of particular foods. I first discuss what is known of the mechanical forces generated by contraction of the walls of the various segments of the gut and the level of diffusive, and advective mixing that it generates within the lumen. I then discuss the particular physical effects that may limit the digestion of solid, physically and/or chemically homogenous and heterogeneous food particles, notably capillarity, porosity, poro-elastic flow and compaction and their likely effects on diffusive and convective mass transfer at particulate surfaces. Similarly, I discuss mucins and morphology on mass transfer of nutrients to the gut wall i.e. the mucosa.
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Affiliation(s)
- R G Lentle
- Digestive Biomechanics Group, College of Health, Massey University, Private Bag 11222, Palmerston North 4442, New Zealand.
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11
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Lentle RG, Hulls CM. Quantifying Patterns of Smooth Muscle Motility in the Gut and Other Organs With New Techniques of Video Spatiotemporal Mapping. Front Physiol 2018; 9:338. [PMID: 29686624 PMCID: PMC5900429 DOI: 10.3389/fphys.2018.00338] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Accepted: 03/20/2018] [Indexed: 01/12/2023] Open
Abstract
The uses and limitations of the various techniques of video spatiotemporal mapping based on change in diameter (D-type ST maps), change in longitudinal strain rate (L-type ST maps), change in area strain rate (A-type ST maps), and change in luminous intensity of reflected light (I-maps) are described, along with their use in quantifying motility of the wall of hollow structures of smooth muscle such as the gut. Hence ST-methods for determining the size, speed of propagation and frequency of contraction in the wall of gut compartments of differing geometric configurations are discussed. We also discuss the shortcomings and problems that are inherent in the various methods and the use of techniques to avoid or minimize them. This discussion includes, the inability of D-type ST maps to indicate the site of a contraction that does not reduce the diameter of a gut segment, the manipulation of axis [the line of interest (LOI)] of L-maps to determine the true axis of propagation of a contraction, problems with anterior curvature of gut segments and the use of adjunct image analysis techniques that enhance particular features of the maps.
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Affiliation(s)
- Roger G Lentle
- Physiology Department, Institute of Food, Nutrition and Human Health, Massey University, Palmerston North, New Zealand
| | - Corrin M Hulls
- Physiology Department, Institute of Food, Nutrition and Human Health, Massey University, Palmerston North, New Zealand
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12
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Wu P, Liao Z, Luo T, Chen L, Chen XD. Enhancement of Digestibility of Casein Powder and Raw Rice Particles in an Improved Dynamic Rat Stomach Model Through an Additional Rolling Mechanism. J Food Sci 2017; 82:1387-1394. [DOI: 10.1111/1750-3841.13683] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 01/01/2017] [Accepted: 02/05/2017] [Indexed: 12/21/2022]
Affiliation(s)
- Peng Wu
- Suzhou Key Laboratory of Green Chemical Engineering, School of Chemical and Environmental Engineering, College of Chemistry, Chemical Engineering and Materials Science; Soochow Univ.; Suzhou 215123 China
- ARC Centre of Excellence in Plant Cell Walls, Centre for Nutrition and Food Sciences, Queensland Alliance for Agriculture and Food Innovation; The Univ. of Queensland; St Lucia 4072 QLD Australia
| | - Zhenkai Liao
- Suzhou Key Laboratory of Green Chemical Engineering, School of Chemical and Environmental Engineering, College of Chemistry, Chemical Engineering and Materials Science; Soochow Univ.; Suzhou 215123 China
- Nantong Dong Concept New Material Technology Ltd; Nantong City Jiangsu Province China
| | - Tingyu Luo
- School of Biology and Basic Medical Science; Soochow Univ.; Suzhou 215123 China
| | - Liding Chen
- Suzhou Key Laboratory of Green Chemical Engineering, School of Chemical and Environmental Engineering, College of Chemistry, Chemical Engineering and Materials Science; Soochow Univ.; Suzhou 215123 China
| | - Xiao Dong Chen
- Suzhou Key Laboratory of Green Chemical Engineering, School of Chemical and Environmental Engineering, College of Chemistry, Chemical Engineering and Materials Science; Soochow Univ.; Suzhou 215123 China
- School of Biology and Basic Medical Science; Soochow Univ.; Suzhou 215123 China
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13
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Wee MSM, Lentle RG, Goh KKT, Matia-Merino L. The first of the viscoceuticals? A shear thickening gum induces gastric satiety in rats. Food Funct 2017; 8:96-102. [DOI: 10.1039/c6fo01464j] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
We examined the effect of gavage of 4 ml of a viscous shear-thickening polysaccharide solution (15% w/w) extracted from the fronds of the mamaku tree fern (Cythea medullaris) in reducing appetite and delaying gastric emptying in twenty six Sprague Dawley rats.
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Affiliation(s)
- M. S. M. Wee
- Massey Institute of Food Science and Technology
- School of Food and Nutrition
- Massey University
- Palmerston North 4442
- New Zealand
| | - R. G. Lentle
- Massey Institute of Food Science and Technology
- School of Food and Nutrition
- Massey University
- Palmerston North 4442
- New Zealand
| | - K. K. T. Goh
- Massey Institute of Food Science and Technology
- School of Food and Nutrition
- Massey University
- Palmerston North 4442
- New Zealand
| | - L. Matia-Merino
- Massey Institute of Food Science and Technology
- School of Food and Nutrition
- Massey University
- Palmerston North 4442
- New Zealand
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14
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Lentle RG, Reynolds GW, Hulls CM, Chambers JP. Advanced spatiotemporal mapping methods give new insights into the coordination of contractile activity in the stomach of the rat. Am J Physiol Gastrointest Liver Physiol 2016; 311:G1064-G1075. [PMID: 27765760 DOI: 10.1152/ajpgi.00308.2016] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Accepted: 10/12/2016] [Indexed: 01/31/2023]
Abstract
We used spatiotemporal mapping of strain rate to determine the direction of propagation and amplitudes of the longitudinal and circumferential components of antrocorporal (AC) contractions and fundal contractions in the rat stomach maintained ex vivo and containing a volume of fluid that was within its normal functional capacity. In the region of the greater curvature the longitudinal and circular components of AC contractions propagated synchronously at right angles to the arciform geometric axis of the stomach. However, the configuration of AC contractions was U shaped, neither the circular nor the longitudinal component of contractions being evident in the upper proximal corpus. Similarly, in the distal upper antrum of some preparations, circumferential components propagated more rapidly than longitudinal components. Ongoing "high-frequency, low-amplitude myogenic contractions" were identified in the upper proximal gastric corpus and on the anterior and posterior wall of the fundus. The amplitudes of these contractions were modulated in the occluded stomach by low-frequency pressure waves that occurred spontaneously. Hence the characteristics of phasic contractions vary regionally in the antrum and corpus and a previously undescribed high-frequency contractile component was identified in the proximal corpus and fundus, the latter being modulated in synchrony with cyclic variation in intrafundal pressure in the occluded fundus.
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Affiliation(s)
- R G Lentle
- Institute of Food, Nutrition and Human Health, Massey University, Palmerston North, New Zealand; and
| | - G W Reynolds
- Institute of Food, Nutrition and Human Health, Massey University, Palmerston North, New Zealand; and
| | - C M Hulls
- Institute of Food, Nutrition and Human Health, Massey University, Palmerston North, New Zealand; and
| | - J P Chambers
- Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Palmerston North, New Zealand
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15
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Wu P, Chen L, Wu X, Chen XD. Digestive behaviours of large raw rice particles in vivo and in vitro rat stomach systems. J FOOD ENG 2014. [DOI: 10.1016/j.jfoodeng.2014.06.010] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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16
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Lueamsaisuk C, Lentle R, MacGibbon A, Matia-Merino L, Golding M. Factors influencing the dynamics of emulsion structure during neonatal gastric digestion in an in vitro model. Food Hydrocoll 2014. [DOI: 10.1016/j.foodhyd.2013.09.013] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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17
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Levi CS, Lesmes U. Bi-compartmental elderly or adult dynamic digestion models applied to interrogate protein digestibility. Food Funct 2014; 5:2402-9. [DOI: 10.1039/c4fo00478g] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Dynamic yet genericin vitrodigestion models enable the comparison of the digestibility of liquid formulations in adults and the elderly.
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Affiliation(s)
- Carmit Shani Levi
- Laboratory of Chemistry of Foods and Bioactives
- Department of Biotechnology and Food Engineering
- Technion – Israel Institute of Technology
- Haifa 32000, Israel
| | - Uri Lesmes
- Laboratory of Chemistry of Foods and Bioactives
- Department of Biotechnology and Food Engineering
- Technion – Israel Institute of Technology
- Haifa 32000, Israel
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18
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Lentle RG, Reynolds GW, Janssen PWM. Gastrointestinal tone; its genesis and contribution to the physical processes of digestion. Neurogastroenterol Motil 2013; 25:931-42. [PMID: 24028606 DOI: 10.1111/nmo.12223] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Accepted: 08/08/2013] [Indexed: 12/24/2022]
Abstract
BACKGROUND Myogenic tone has long been recognised as an important component of gastrointestinal motility. Recent work has clarified the cellular mechanisms that engender tone and the neurogenic and mechanical stimuli that modulate it but has also highlighted cellular and regional specialisation in these mechanisms within the GI tract. Smooth muscle in all segments of the gut has the capability of latching, i.e. can generate ongoing specific rather than tetanic tone. This is likely modulated by both direct and indirect input from agonists such as acetylcholine and mechanoreceptors, the latter originating in ICC-IM, smooth muscle cells or elements of the ENS. Tonic contraction can occur in the absence of phasic contractions or concurrent with them, and it can modulate wall compliance and the capacity of particular segments, thereby affecting the level of on-flow and mixing, both luminal and adjacent to the mucosa. PURPOSE The review seeks to provide an overview of our understanding of the mechanism by which tone is generated and maintained, highlighting its modulation by neurogenic and mechanical stimuli, its mechanical consequences in the walls of the various segments of the gastrointestinal tract and its contribution to flow and mixing of contained digesta.
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Affiliation(s)
- R G Lentle
- Institute of Food, Nutrition and Human Health, Massey University, Palmerston North, New Zealand
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19
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Richardson J, Cruz MT, Majumdar U, Lewin A, Kingsbury KA, Dezfuli G, Vicini S, Verbalis JG, Dretchen KL, Gillis RA, Sahibzada N. Melanocortin signaling in the brainstem influences vagal outflow to the stomach. J Neurosci 2013; 33:13286-99. [PMID: 23946387 PMCID: PMC3742919 DOI: 10.1523/jneurosci.0780-13.2013] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2013] [Revised: 06/11/2013] [Accepted: 06/13/2013] [Indexed: 01/23/2023] Open
Abstract
Activation of melanocortin 4 receptors (MC4-Rs) in brain nuclei associated with food intake profoundly influences consummatory behavior. Of these nuclei, the dorsal motor vagal nucleus (DMV), which has a dense concentration of MC4-Rs, is an important regulator of gastric tone and motility. Hence, the present study sought to examine the role of MC4-Rs in this nucleus on these activities. Using an in vivo approach, MC4-R agonists, melanotan-II (MT-II) or α-melanocyte stimulating hormone (α-MSH), were unilaterally microinjected into the DMV of rats, and their effects were noted on gastric activity. MT-II decreased phasic contractions, whereas α-MSH increased their amplitude. Both effects were blocked by the MC4-R antagonist SHU9119 or by ipsilateral vagotomy. Microinjection of the agonists (MT-II and α-MSH) into the overlying nucleus of the solitary tract (NTS), an important component of "vago-vagal" gastric circuitry, decreased phasic contractions. In addition, α-MSH reduced gastric tone and mean arterial blood pressure. To study the underlying mechanisms of the effect of MC4-R stimulation on gastric activity, electrophysiological recordings were made from labeled DMV antrum neurons in rat pups and MC4-R(-/-) mice. Bath application of MT-II or α-MSH significantly reduced spontaneous action potentials (but not in MC4-R(-/-) mice). However, in low-calcium ACSF, MT-II decreased neuronal firing, whereas α-MSH increased it. These effects mirror those of our in vivo DMV studies. Altogether, our novel findings show that activation of MC4-Rs in the brainstem, particularly in the medial NTS by the endogenous peptide α-MSH, modulates gastric activity, which may have physiological relevance for food intake and gastric function.
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Affiliation(s)
| | - Maureen T. Cruz
- Interdisciplinary Program in Neuroscience, Georgetown University Medical Center, Washington, DC 20057
| | | | | | | | - Ghazaul Dezfuli
- Interdisciplinary Program in Neuroscience, Georgetown University Medical Center, Washington, DC 20057
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21
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de Loubens C, Lentle RG, Love RJ, Hulls C, Janssen PWM. Fluid mechanical consequences of pendular activity, segmentation and pyloric outflow in the proximal duodenum of the rat and the guinea pig. J R Soc Interface 2013; 10:20130027. [PMID: 23536539 PMCID: PMC3645412 DOI: 10.1098/rsif.2013.0027] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2013] [Accepted: 03/06/2013] [Indexed: 11/12/2022] Open
Abstract
We conducted numerical experiments to study the influence of non-propagating longitudinal and circular contractions, i.e. pendular activity and segmentation, respectively, on flow and mixing in the proximal duodenum. A lattice-Boltzmann numerical method was developed to simulate the fluid mechanical consequences for each of 22 randomly selected sequences of high-definition video of real longitudinal and radial contractile activity in the isolated proximal duodenum of the rat and guinea pig. During pendular activity in the rat duodenum, the flow was characterized by regions of high shear rate. Mixing was so governed by shearing deformation of the fluid that increased the interface between adjacent domains and accelerated their inter-diffusion (for diffusion coefficients approx. less than 10(-8) m² s(-1)). When pendular activity was associated with a slow gastric outflow characteristic of post-prandial period, the dispersion was also improved, especially near the walls. Mixing was not promoted by isolated segmentative contractions in the guinea pig duodenum and not notably influenced by pylorus outflow. We concluded that pendular activity generates mixing of viscous fluids 'in situ' and accelerates the diffusive mass transfer, whereas segmentation may be more important in mixing particulate suspensions with high solid volume ratios.
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Affiliation(s)
- Clément de Loubens
- UMR 782 Génie et Microbiologie des Procédés Alimentaires, INRA, AgroParisTech, CBAI 78850 Thiverval Grignon, France.
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22
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Rheological Properties and Textural Attributes of Cooked Brown and White Rice During Gastric Digestion in Vivo. FOOD BIOPHYS 2013. [DOI: 10.1007/s11483-013-9288-1] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Lentle R, Reynolds G, de Loubens C, Hulls C, Janssen P, Ravindran V. Spatiotemporal mapping of the muscular activity of the gizzard of the chicken (Gallus domesticus). Poult Sci 2013; 92:483-91. [DOI: 10.3382/ps.2012-02689] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
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24
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Janssen PWM, Lentle RG. Spatiotemporal Mapping Techniques for Quantifying Gut Motility. LECTURE NOTES IN COMPUTATIONAL VISION AND BIOMECHANICS 2013. [DOI: 10.1007/978-94-007-6561-0_12] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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Bornhorst GM, Ströbinger N, Rutherfurd SM, Singh RP, Moughan PJ. Properties of Gastric Chyme from Pigs Fed Cooked Brown or White Rice. FOOD BIOPHYS 2012. [DOI: 10.1007/s11483-012-9277-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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26
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Fung C, Ellis M, Bornstein JC. Luminal Cholera Toxin Alters Motility in Isolated Guinea-Pig Jejunum via a Pathway Independent of 5-HT(3) Receptors. Front Neurosci 2010; 4:162. [PMID: 21048896 PMCID: PMC2967348 DOI: 10.3389/fnins.2010.00162] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2010] [Accepted: 08/16/2010] [Indexed: 12/17/2022] Open
Abstract
Cholera toxin (CT) is well established to produce diarrhea by producing hyperactivity of the enteric neural circuits that regulate water and electrolyte secretion. Its effects on intestinal motor patterns are less well understood. We examined the effects of luminal CT on motor activity of guinea-pig jejunum in vitro. Segments of jejunum were cannulated at either end and mounted horizontally. Their contractile activity was video-imaged and the recordings were used to construct spatiotemporal maps of contractile activity with CT (1.25 or 12.5 μg/ml) in the lumen. Both concentrations of CT induced propulsive motor activity in jejunal segments. The effect of 1.25 μg/ml CT was markedly enhanced by co-incubation with granisetron (5-HT3 antagonist, 1 μM), which prevents the hypersecretion induced by CT. The increased propulsive activity was not accompanied by increased segmentation and occurred very early after exposure to CT in the presence of granisetron. Luminal CT also reduced the pressure threshold for saline distension evoked propulsive reflexes, an effect resistant to granisetron. In contrast, CT prevented the induction of segmenting contractions by luminal decanoic acid, so its effects on propulsive and segmenting contractile activity are distinctly different. Thus, in addition to producing hypersecretion, CT excites propulsive motor activity with an entirely different time course and pharmacology, but inhibits nutrient-induced segmentation. This suggests that CT excites more than one enteric neural circuit and that propulsive and segmenting motor patterns are differentially regulated.
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Affiliation(s)
- Candice Fung
- Department of Physiology, University of Melbourne Parkville, VIC, Australia
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