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Kazemi S, Hashem R, Stommel M, Cheng LK, Xu W. Biomimetic Closed-Loop Control of a Novel Soft Gastric Simulator Toward Emulating Antral Contraction Waves. Soft Robot 2024; 11:684-697. [PMID: 38252793 DOI: 10.1089/soro.2023.0097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2024] Open
Abstract
Soft gastric simulators are in vitro biomimetic modules that can reproduce the antral contraction waves (ACWs). Along with providing information concerning stomach contents, stomach simulators enable experts to evaluate the digestion process of foods and drugs. Traditionally, open-loop control approaches were implemented on stomach simulators to produce ACWs. Constructing a closed-loop control system is essential to improve the simulator's ability to imitate ACWs in additional scenarios and avoid constant tuning. Closed-loop control can enhance stomach simulators in accuracy, responding to various food and drug contents, timing, and unknown disturbances. In this article, a new generation of anatomically realistic soft pneumatic gastric simulators is designed and fabricated. The presented simulator represents the antrum, the lower portion of the stomach where ACWs occur. It is equipped with a real-time feedback system to implement diverse closed-loop controllers on demand. All the details of the physical design, fabrication, and assembly process are discussed. Also, the measures taken for the mechatronics design and sensory system are highlighted in this article. Through several implementation algorithms and techniques, three closed-loop controllers, including model-based and model-free schemes are designed and successfully applied on the presented simulator to imitate ACWs. All the experimental outcomes are carefully analyzed and compared against the biological counterparts. It is demonstrated that the presented simulator can serve as a reliable tool and method to scrutinize digestion and promote novel technologies around the human stomach and the digestion process. This research methodology can also be utilized to develop other biomimetic and bioinspired applications.
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Affiliation(s)
- Shahab Kazemi
- Department of Mechanical and Mechatronics Engineering, The University of Auckland, Auckland, New Zealand
| | - Ryman Hashem
- Department of Medical Physics and Bioengineering, University College London, London, England
| | - Martin Stommel
- Department of Electrical and Electronic Engineering, Auckland University of Technology, Auckland, New Zealand
| | - Leo K Cheng
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | - Weiliang Xu
- Department of Mechanical and Mechatronics Engineering, The University of Auckland, Auckland, New Zealand
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2
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Swackhamer C, Bedane T, Keppler S, Poltorak A, Cheung K, Awais N, Marra F, Bornhorst GM. Development and analysis of a multi-module peristaltic simulator for gastrointestinal research. Food Res Int 2023; 170:112877. [PMID: 37316038 DOI: 10.1016/j.foodres.2023.112877] [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: 12/15/2022] [Revised: 03/06/2023] [Accepted: 04/20/2023] [Indexed: 06/16/2023]
Abstract
Many existing in vitro digestion systems do not accurately represent the peristaltic contractions of the gastrointestinal system; most of the systems that have physiologically-relevant peristaltic contractions have low throughput and can only test one sample at a time. A device has been developed that provides simulated peristaltic contractions for up to 12 digestion modules simultaneously using rollers of varying width to modulate the dynamics of the peristaltic motion. The force applied to a simulated food bolus varied from 2.61 ± 0.03 N to 4.51 ± 0.16 N (p < 0.05) depending on roller width. Video analysis showed that the degree of occlusion of the digestion module varied from 72.1 ± 0.4% to 84.6 ± 1.2% (p < 0.05). A multiphysics, computational fluid dynamics model was created to understand the fluid flow. The fluid flow was also examined experimentally using video analysis of tracer particles. The model-predicted maximum fluid velocity in the peristaltic simulator incorporating the thin rollers was 0.016 m/s, and the corresponding value measured using tracer particles was 0.015 m/s. The occlusion, pressure, and fluid velocity in the new peristaltic simulator fell within physiologically representative ranges. Although no in vitro device perfectly recreates the conditions of the gastrointestinal system, this novel device is a flexible platform for future gastrointestinal research and could allow for high-throughput screening of food materials for health-promoting properties under conditions representative of human gastrointestinal motility.
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Affiliation(s)
- Clay Swackhamer
- Department of Biological and Agricultural Engineering, University of California, Davis, USA
| | - Tesfaye Bedane
- UCD School of Agriculture and Food Science, University College Dublin, Dublin, Ireland
| | - Silvia Keppler
- Department of Biological and Agricultural Engineering, University of California, Davis, USA
| | - Adam Poltorak
- Department of Biological and Agricultural Engineering, University of California, Davis, USA
| | - Kyle Cheung
- Department of Biological and Agricultural Engineering, University of California, Davis, USA
| | - Nashea Awais
- Department of Biological and Agricultural Engineering, University of California, Davis, USA
| | - Francesco Marra
- Dipartimento di Ingegneria Industriale, Università degli Studi di Salerno, 84084 Fisciano, Italy
| | - Gail M Bornhorst
- Department of Biological and Agricultural Engineering, University of California, Davis, USA; Riddet Institute, Palmerston North, New Zealand.
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3
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Hosseini S, Avci R, Paskaranandavadivel N, Suresh V, Cheng LK. Quantification of the Regional Properties of Gastric Motility Using Dynamic Magnetic Resonance Images. IEEE OPEN JOURNAL OF ENGINEERING IN MEDICINE AND BIOLOGY 2023; 4:38-44. [PMID: 37138590 PMCID: PMC10151011 DOI: 10.1109/ojemb.2023.3261224] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Revised: 01/16/2023] [Accepted: 03/14/2023] [Indexed: 05/05/2023] Open
Abstract
Goal: To quantify the regional properties of gastric motility from free-breathing dynamic MRI data. Methods: Free-breathing MRI scans were performed on 10 healthy human subjects. Motion correction was applied to reduce the respiratory effect. A stomach centerline was automatically generated and used as a reference axis. Contractions were quantified and visualized as spatio-temporal contraction maps. Gastric motility properties were reported separately for the lesser and greater curvatures in the proximal and distal regions of the stomach. Results: Motility properties varied in different regions of the stomach. The mean contraction frequencies for the lesser and greater curvatures were both 3.1±0.4 cycles per minute. The contraction speed was significantly higher on the greater curvature than the lesser curvature (3.5±0.7 vs 2.5±0.4 mm/s, p<0.001) while contraction size on both curvatures was comparable (4.9±1.2 vs 5.7±2.4 mm, p = 0.326). The mean gastric motility index was significantly higher in the distal greater curvature (28.13±18.89 mm2/s) compared to the other regions of the stomach (11.16-14.12 mm2/s). Conclusions: The results showed the effectiveness of the proposed method for visualization and quantification of motility patterns from MRI data.
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Affiliation(s)
- Saeed Hosseini
- Auckland Bioengineering InstituteUniversity of Auckland Auckland 1010 New Zealand
- Riddet Institute Palmerston North 4474 New Zealand
| | - Recep Avci
- Auckland Bioengineering InstituteUniversity of Auckland Auckland 1010 New Zealand
| | | | - Vinod Suresh
- Auckland Bioengineering InstituteUniversity of Auckland Auckland 1010 New Zealand
- Department of Engineering ScienceUniversity of Auckland Auckland 1010 New Zealand
| | - Leo K Cheng
- Auckland Bioengineering InstituteUniversity of Auckland Auckland 1010 New Zealand
- Riddet InstitutePalmerston North 4474 New Zealand
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4
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Driever T, Hulshof MCCM, Bel A, Sonke JJ, van der Horst A. Quantifying intrafractional gastric motion using auto-segmentation on MRI: Deformation and respiratory-induced displacement compared. J Appl Clin Med Phys 2022; 24:e13864. [PMID: 36565168 PMCID: PMC10113698 DOI: 10.1002/acm2.13864] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 11/02/2022] [Accepted: 11/23/2022] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND AND PURPOSE For accurate pre-operative gastric radiotherapy, intrafractional changes must be taken into account. The aim of this study is to quantify local gastric deformations and compare these deformations with respiratory-induced displacement. MATERIALS AND METHODS Coronal 2D MRI scans (15-16 min; 120 repetitions of 25-27 interleaved slices) were obtained for 18 healthy volunteers. A deep-learning network was used to auto-segment the stomach. To separate out respiratory-induced displacements, auto-segmentations were rigidly shifted in superior-inferior (SI) direction to align the centre of mass (CoM) within every slice. From these shifted auto-segmentations, 3D iso-probability surfaces (isosurfaces) were established: a reference surface for POcc = 0.50 and 50 other isosurfaces (from POcc = 0.01 to 0.99), with POcc indicating the probability of occupation by the stomach. For each point on the reference surface, distances to all isosurfaces were determined and a cumulative Gaussian was fitted to this probability-distance dataset to obtain a standard deviation (SDdeform ) expressing local deformation. For each volunteer, we determined median and 98th percentile of SDdeform over the reference surface and compared these with the respiratory-induced displacement SDresp , that is, the SD of all CoM shifts (paired Wilcoxon signed-rank, α = 0.05). RESULTS Larger deformations were mostly seen in the antrum and pyloric region. Median SDdeform (range, 2.0-2.9 mm) was smaller than SDresp (2.7-8.8 mm) for each volunteer (p < 0.00001); 98th percentile of SDdeform (3.2-7.3 mm) did not significantly differ from SDresp (p = 0.13). CONCLUSION Locally, gastric deformations can be large. Overall, however, these deformations are limited compared to respiratory-induced displacement. Therefore, unless respiratory motion is considerably reduced, the need to separately include these deformation uncertainties in the treatment margins may be limited.
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Affiliation(s)
- Theo Driever
- Department of Radiation Oncology, The Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Maarten C C M Hulshof
- Department of Radiation Oncology, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Arjan Bel
- Department of Radiation Oncology, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Jan-Jakob Sonke
- Department of Radiation Oncology, The Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Astrid van der Horst
- Department of Radiation Oncology, The Netherlands Cancer Institute, Amsterdam, The Netherlands.,Department of Radiation Oncology, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
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5
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Hashem R, Kazemi S, Stommel M, Cheng LK, Xu W. SoRSS: A Soft Robot for Bio-Mimicking Stomach Anatomy and Motility. Soft Robot 2022. [DOI: 10.1089/soro.2021.0202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Affiliation(s)
- Ryman Hashem
- Department of Mechanical and Mechatronics Engineering, The University of Auckland, Auckland, New Zealand
| | - Shahab Kazemi
- Department of Mechanical and Mechatronics Engineering, The University of Auckland, Auckland, New Zealand
- Riddet Institute Centre of Research Excellence (CoRE), Palmerston North, New Zealand
| | - Martin Stommel
- Riddet Institute Centre of Research Excellence (CoRE), Palmerston North, New Zealand
- Department of Electrical and Electronic Engineering, Auckland University of Technology, Auckland, New Zealand
| | - Leo K. Cheng
- Riddet Institute Centre of Research Excellence (CoRE), Palmerston North, New Zealand
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | - Weiliang Xu
- Department of Mechanical and Mechatronics Engineering, The University of Auckland, Auckland, New Zealand
- Riddet Institute Centre of Research Excellence (CoRE), Palmerston North, New Zealand
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6
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Li Y, Kong F. Simulating human gastrointestinal motility in dynamic in vitro models. Compr Rev Food Sci Food Saf 2022; 21:3804-3833. [PMID: 35880687 DOI: 10.1111/1541-4337.13007] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 03/26/2022] [Accepted: 06/22/2022] [Indexed: 01/28/2023]
Abstract
The application of dynamic in vitro gastrointestinal (GI) models has grown in popularity to understand the impact of food structure and composition on human health. Given that GI motility is integral to digestion and absorption, a predictive in vitro model should faithfully replicate the motility patterns and motor functions in vivo. In this review, typical characteristics of gastric and small intestinal motility in humans as well as the biomechanical and hydrodynamic events pertinent to gut motility are summarized. The simulation of GI motility in the presently existing dynamic in vitro models is discussed from an engineering perspective and categorized into hydraulic, piston/probe-driven, roller-driven, pneumatic, and other systems. Each system and its representative models are evaluated in terms of their motility patterns, the key hydrodynamic characteristics concerning gut motility, their performance in simulating the key physiological events, and their ability to establish in vitro-in vivo correlations. Practical Application: The review paper provided useful information in the design of dynamic GI models and the simulation of human gastric and small intestinal motility which are important for understanding food and health.
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Affiliation(s)
- Yiwen Li
- Department of Food Science and Technology, College of Agricultural and Environmental Sciences, University of Georgia, Athens, Georgia, USA
| | - Fanbin Kong
- Department of Food Science and Technology, College of Agricultural and Environmental Sciences, University of Georgia, Athens, Georgia, USA
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7
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Rochira I, Chanpong A, Biassoni L, Easty M, Morris E, Saliakellis E, Lindley K, Thapar N, Rybak A, Borrelli O. Transpyloric propagation and liquid gastric emptying in children with foregut dysmotility. Neurogastroenterol Motil 2022; 34:e14334. [PMID: 35254724 DOI: 10.1111/nmo.14334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 09/14/2021] [Accepted: 01/19/2022] [Indexed: 02/08/2023]
Abstract
BACKGROUND/OBJECTIVES Gastric emptying (GE) requires precise antropyloroduodenal coordination for effective transpyloric flow, the mechanisms of which are still unclear. We aimed to correlate gastric antral function assessed by antroduodenal manometry (ADM) with GE scintigraphy (GES) for liquid feeds in children with suspected gastrointestinal dysmotility. METHODS Children who underwent both ADM and GES over a five-year period were reviewed. ADM tracings were re-analyzed to assess antral frequency, amplitude, and motility index (MI) pre-prandially and postprandially. Transpyloric propagation (TPP) was defined as antegrade propagated antral activity preceding duodenal phase III of the migrating motor complex (MMC). TPP was defined as "poor" if occurring in <50% of all presented duodenal phases III. For GES, regions of interest over the whole stomach, fundus, and antrum were drawn to calculate GE half-time (GE-T1/2 ) and retention rate (RR) in each region at 1 and 2 h. RESULTS Forty-seven children (median age: 7.0 years) were included. Twenty-two had PIPO, 14 functional GI disorders, and 11 gastroparesis. Children with poor TPP had longer GE-T1/2 (113.0 vs 66.5 min, p = 0.028), higher RR of the whole stomach and fundus at 1 h (79.5% vs 63.5%, p = 0.038; 60.0% vs 41.0%, p = 0.022, respectively) and 2 h (51.0% vs 10.5%, p = 0.005; 36.0% vs 6.5%, p = 0.004, respectively). The pre-prandial antral amplitude of contractions inversely correlated with GE-T1/2 , RR of the whole stomach, and fundus at 2 h. CONCLUSIONS TPP during phase III of the MMC correlated with gastric emptying of liquid and its assessment on ADM might predict abnormalities in postprandial gastric function.
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Affiliation(s)
- Ilaria Rochira
- Neurogastroenterology & Motility Unit, Gastroenterology Department, Great Ormond Street Hospital for Children, London, UK.,Department of Paediatrics, Children's Hospital, ASST Spedali Civili, University of Brescia, Brescia, Italy
| | - Atchariya Chanpong
- Neurogastroenterology & Motility Unit, Gastroenterology Department, Great Ormond Street Hospital for Children, London, UK.,Division of Gastroenterology and Hepatology, Department of Pediatrics, Faculty of Medicine, Prince of Songkla University, Songkhla, Thailand.,Stem cell and Regenerative Medicine, UCL Great Ormond Street Institute of Child Health, London, UK
| | - Lorenzo Biassoni
- Nuclear Medicine Unit, Department of Radiology, Great Ormond Street Hospital for Children, London, UK
| | - Marina Easty
- Nuclear Medicine Unit, Department of Radiology, Great Ormond Street Hospital for Children, London, UK
| | - Elizabeth Morris
- Nuclear Medicine Unit, Department of Radiology, Great Ormond Street Hospital for Children, London, UK.,Nuclear Medicine Physics, Clinical Physics, Barts Health NHS Trust, London, UK
| | - Efstratios Saliakellis
- Neurogastroenterology & Motility Unit, Gastroenterology Department, Great Ormond Street Hospital for Children, London, UK
| | - Keith Lindley
- Neurogastroenterology & Motility Unit, Gastroenterology Department, Great Ormond Street Hospital for Children, London, UK
| | - Nikhil Thapar
- Neurogastroenterology & Motility Unit, Gastroenterology Department, Great Ormond Street Hospital for Children, London, UK.,Stem cell and Regenerative Medicine, UCL Great Ormond Street Institute of Child Health, London, UK.,Gastroenterology, Hepatology and Liver Transplant, Queensland Children's Hospital, Brisbane, Queensland, Australia
| | - Anna Rybak
- Neurogastroenterology & Motility Unit, Gastroenterology Department, Great Ormond Street Hospital for Children, London, UK
| | - Osvaldo Borrelli
- Neurogastroenterology & Motility Unit, Gastroenterology Department, Great Ormond Street Hospital for Children, London, UK
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8
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Kazemi S, Stommel M, Cheng LK, Xu W. Finite-Time Contraction Control of a Ring-Shaped Soft Pneumatic Actuator Mimicking Gastric Pathologic Motility Conditions. Soft Robot 2022; 10:221-233. [PMID: 35704909 DOI: 10.1089/soro.2021.0167] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Soft gastric simulators are the latest gastric models designed to imitate gastrointestinal (GI) functions in actual physiological conditions. They are used in in vitro tests for examining the drug and food behaviors in the GI tract. As the main motility function of the GI tract, the peristalsis can be altered in some gastric disorders, for example, by being delayed or accelerated. To simulate the stomach motility, a GI simulator must achieve a prescribed healthy or pathological peristalsis. This requires the simulator to be controlled in a closed loop. Unlike conventional controllers that stabilize a controlled plant asymptotically, a finite-time controller regulates state variables to their equilibrium points in a predetermined time interval. This article presents the design and implementation of a finite-time, model-based state feedback controller (based on the differential Riccati equation) on a soft robotic gastric simulator's actuators for the first time. We propose a mass-spring-damper model of a ring-shaped soft pneumatic actuator (RiSPA). RiSPA is a bellows-driven, elastomer-based actuator developed to reproduce motility functions of the lower part of the stomach (pyloric antrum). The proposed model is augmented by a new approach for modeling the soft tissues, where the moments of inertia of the system constituents are considered as time-varying functions. The finite-time controller is successfully applied on the RiSPA in numerical simulation and experimental implementation, and the results were thoroughly analyzed and discussed. Its accuracy and the ability to control in a predetermined time are highlighted in the tracking of peristalsis trajectory and contractive regulations.
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Affiliation(s)
- Shahab Kazemi
- Department of Mechanical and Mechatronics Engineering, The University of Auckland, Auckland, New Zealand.,Riddet Institute, Palmerston North, New Zealand
| | - Martin Stommel
- Department of Electrical & Electronic Engineering, Auckland University of Technology, Auckland, New Zealand
| | - Leo K Cheng
- Riddet Institute, Palmerston North, New Zealand.,Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | - Weiliang Xu
- Department of Mechanical and Mechatronics Engineering, The University of Auckland, Auckland, New Zealand.,Riddet Institute, Palmerston North, New Zealand
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9
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Gao Z, Cao LNY, Liu X, Tian L, Rodriguez JD. An In Vitro Dissolution Method for Testing Extended-Release Tablets Under Mechanical Compression and Sample Friction. J Pharm Sci 2021; 111:1652-1658. [PMID: 34742730 DOI: 10.1016/j.xphs.2021.10.036] [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: 06/23/2021] [Revised: 10/29/2021] [Accepted: 10/29/2021] [Indexed: 11/29/2022]
Abstract
The release and dissolution of an active pharmaceutical ingredient (API) from the solid oral formulation into the gastrointestinal (GI) tract is critical for the drug's absorption into systemic circulation. Extended-release (ER) solid oral dosage forms are normally subjected to physical shear and grinding forces as well as pressure exerted by peristaltic movements when passing through the GI tract. The complex physical contraction and sample friction exerted by the GI tract are not simulated well by compendial dissolution methods. These limitations render traditional in vitro dissolution testing unable to discriminate and predict a product's in vivo performance. The objective of this study was to develop a dissolution method that better simulates the GI environment that products are subject to when taken by patients. A newly designed Mechanical Apparatus under GI Conditions (MAGIC) was assembled with a dissolution platform and mechanical capabilities to allow in vitro dissolution testing under sample contractions and friction. The dissolution platform, with medium flow-through configuration, was manufactured by 3D printing. A 60 mg polymer matrix-based ER nifedipine product was tested. To simulate GI physiological conditions during the dissolution testing, the flow rate of the medium, and a combination of mechanical compression with rotation induced sample friction at various rotation frequencies were explored. The polymer matrix-based nifedipine ER formulation used here failed its controlled release functionality in the simulated GI environment under mechanical compression and sample friction. The results showed that the MAGIC system, with flow-through configuration under compression and sample friction, has advantages over compendial methods in testing ER solid oral formulations.
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Affiliation(s)
- Zongming Gao
- US Food and Drug Administration, Center for Drug Evaluation and Research, Division of Complex Drug Analysis, St. Louis, MO, 63110.
| | - Leo N Y Cao
- US Food and Drug Administration, Center for Drug Evaluation and Research, Division of Complex Drug Analysis, St. Louis, MO, 63110
| | - Xiaofei Liu
- US Food and Drug Administration, Center for Drug Evaluation and Research, Division of Complex Drug Analysis, St. Louis, MO, 63110
| | - Li Tian
- US Food and Drug Administration, Center for Drug Evaluation and Research, Division of Complex Drug Analysis, St. Louis, MO, 63110
| | - Jason D Rodriguez
- US Food and Drug Administration, Center for Drug Evaluation and Research, Division of Complex Drug Analysis, St. Louis, MO, 63110
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10
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Hosseini S, Avci R, Paskaranandavadivel N, Suresh V, Cheng LK. Quantification of Gastric Contractions Using MRI with a Natural Contrast Agent. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2021; 2021:3601-3604. [PMID: 34892017 DOI: 10.1109/embc46164.2021.9629601] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Gastric motility has an essential role in mixing and the breakdown of ingested food. It can affect the digestion process and the efficacy of the orally administered drugs. There are several methods to image, measure, and quantify gastric motility. MRI has been shown to be a suitable non-invasive method for gastric motility imaging. However, in most studies, gadolinium-based agents have been used as an oral contrast agent, making it less desirable for general usage. In this study, MRI scans were performed on 4 healthy volunteers, where pineapple juice was used as a natural contrast agent for imaging gastric motility. A novel method was developed to automatically estimate a curved centerline of the stomach. The centerline was used as a reference to quantify contraction magnitudes. The results were visualized as contraction magnitude-maps. The mean speed of each contraction wave on the lesser and greater curvatures of the stomach was calculated, and the variation of the speeds in 4 regions of the stomach were quantified. There were 3-4 contraction waves simultaneously present in the stomach for all cases. The mean speed of all contractions was 2.4±0.9 mm/s, and was in agreement with previous gastric motility studies. The propagation speed of the contractions in the greater curvature was higher in comparison to the lesser curvature (2.9±0.8 vs 1.9±0.5 mm/s); however, the speeds were more similar near to the pylorus. This study shows the feasibility of using pineapple juice as a natural oral contrast agent for the MRI measurements of gastric motility. Also, it demonstrated the viability of the proposed method for automatic curved centerline estimation, which enables practical clinical translation.Clinical Relevance- MRI is able to non-invasively provide dynamic images of the contraction patterns of the stomach, providing a novel clinical tool for assessing functional motility disorders. The use of a natural oral contrast agent such as pineapple juice, as opposed to a gadolinium-based contrast agent, makes MRI more widely accessible. Our semi-automated methods for quantifying contraction magnitude and speed will streamline analysis and clinical diagnosis.
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11
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Hashem R, Kazemi S, Stommel M, Cheng LK, Xu W. A Biologically Inspired Ring-Shaped Soft Pneumatic Actuator for Large Deformations. Soft Robot 2021; 9:807-819. [PMID: 34704835 DOI: 10.1089/soro.2021.0013] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Biomimicry of the stomach's peristaltic contractions can be challenging in the design, modeling, and control of a soft actuator. The mimicking of organ contractions advances our knowledge of the digestive system and analyzes the biological behavior by testing with a physical robot. This article proposes a ring-shaped soft pneumatic actuator (RiSPA) as a segment of the digestive tract. RiSPA is made of a ring frame with embedded bellow actuators that generate contractive motions. An embedded sensory system measures the contraction using range sensors. The kinematics and dynamics of RiSPA's contraction are modeled and simulated, while a state feedback algorithm is applied to them. The simulation results are validated experimentally by comparing the RiSPA measurements with desired applied signals. The proposed actuator provides controllable symmetrical and asymmetrical contractions analog to the human stomach. The results of RiSPA validate the prediction performance of the simulation and controller with applied sinusoidal signals as a peristaltic wave. RiSPA contractions can be applied to a broad range of applications, such as imitating the esophagus and intestine contractions.
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Affiliation(s)
- Ryman Hashem
- Department of Mechanical and Mechatronics Engineering, The University of Auckland, Auckland, New Zealand.,The Medical Technologies Centre of Research Excellence, Auckland, New Zealand
| | - Shahab Kazemi
- Department of Mechanical and Mechatronics Engineering, The University of Auckland, Auckland, New Zealand.,The Medical Technologies Centre of Research Excellence, Auckland, New Zealand
| | - Martin Stommel
- The Medical Technologies Centre of Research Excellence, Auckland, New Zealand.,Riddet Institute, Palmerston North, New Zealand
| | - Leo K Cheng
- The Medical Technologies Centre of Research Excellence, Auckland, New Zealand.,Department of Electrical and Electronic Engineering, Auckland University of Technology, Auckland, New Zealand.,Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | - Weiliang Xu
- Department of Mechanical and Mechatronics Engineering, The University of Auckland, Auckland, New Zealand.,The Medical Technologies Centre of Research Excellence, Auckland, New Zealand.,Department of Electrical and Electronic Engineering, Auckland University of Technology, Auckland, New Zealand
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12
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Neumann M, Heimhardt C, Seidlitz K, Koziolek M, Schneider F, Schiller C, Hanke U, Anschütz M, Knopke C, Donath F, Thoma R, Brätter C, Schug B, Franke H, Weitschies W. Development of a furosemide-containing expandable system for gastric retention. J Control Release 2021; 338:105-118. [PMID: 34416321 DOI: 10.1016/j.jconrel.2021.08.026] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Revised: 07/28/2021] [Accepted: 08/16/2021] [Indexed: 10/20/2022]
Abstract
More than 50 years ago, the first gastroretentive dosage forms came up. Since then, no practical and at the same time reliable gastroretentive system is available on market. A major obstacle in the development of novel gastroretentive systems is the lack of proper predictive test methods. In the present work, we aimed at developing and fully characterizing an expandable gastroretentive system containing furosemide as model drug. On the one hand, we used well-established in vitro tests for drug dissolution and gastroretentive properties (paddle apparatus, swelling characteristics). On the other hand, we used two novel models (dissolution stress test device, mechanical antrum model) to assess these properties under biorelevant conditions. Moreover, we performed an in vivo study under fed and fasted conditions that combined blood sampling and a high-resolution imaging technique (magnetic marker monitoring) to determine gastrointestinal location with the assessment of a pharmacodynamic endpoint (urinary sodium excretion). In vitro dissolution tests confirmed prolonged drug release over more than 8 h independent from pH and with slight pressure sensitivity. Swelling studies indicated good swelling behavior within 4 h along with medium gastroretentive properties as determined with the mechanical antrum model. In vivo imaging showed prolonged gastric residence time after fed compared to fasted administration (481 min vs 38 min). Comparison of geometric means of AUCo-tlast of the model drug confirmed this observation with 10 times higher value after fed administration. Urinary excretion of sodium well reflected the increased sodium-reuptake inhibition due to higher furosemide exposure under fed conditions. However, the poor performance after fasted intake of the system is in line with data from several other gastroretentive formulations. The present study highlighted the value of novel test methods during the development of gastroretentive formulations. Yet, a system with reproducible gastroretentive properties especially under fasted conditions has to be designed.
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Affiliation(s)
- Marco Neumann
- Institute of Pharmacy, Department of Biopharmaceutics & Pharmaceutical Technology, Center of Drug Absorption and Transport, University of Greifswald, Felix-Hausdorff-Str. 3, 17487 Greifswald, Germany
| | - Claudia Heimhardt
- Institute of Pharmacy, Department of Biopharmaceutics & Pharmaceutical Technology, Center of Drug Absorption and Transport, University of Greifswald, Felix-Hausdorff-Str. 3, 17487 Greifswald, Germany
| | - Knut Seidlitz
- LTS Lohmann Therapie Systeme AG, LTS Lohmann Therapie-Systeme AG, Lohmannstr. 2, D-56626 Andernach, Germany
| | - Mirko Koziolek
- Institute of Pharmacy, Department of Biopharmaceutics & Pharmaceutical Technology, Center of Drug Absorption and Transport, University of Greifswald, Felix-Hausdorff-Str. 3, 17487 Greifswald, Germany
| | - Felix Schneider
- Institute of Pharmacy, Department of Biopharmaceutics & Pharmaceutical Technology, Center of Drug Absorption and Transport, University of Greifswald, Felix-Hausdorff-Str. 3, 17487 Greifswald, Germany
| | - Christiane Schiller
- LTS Lohmann Therapie Systeme AG, LTS Lohmann Therapie-Systeme AG, Lohmannstr. 2, D-56626 Andernach, Germany
| | - Ulrike Hanke
- LTS Lohmann Therapie Systeme AG, LTS Lohmann Therapie-Systeme AG, Lohmannstr. 2, D-56626 Andernach, Germany
| | | | | | - Frank Donath
- SocraTec R&D, Im Setzling 35, 61440 Oberursel, Germany
| | - Rudy Thoma
- Formula GmbH, Grenzallee 305b, 14167 Berlin, Germany
| | | | - Barbara Schug
- SocraTec R&D, Im Setzling 35, 61440 Oberursel, Germany
| | - Hanshermann Franke
- LTS Lohmann Therapie Systeme AG, LTS Lohmann Therapie-Systeme AG, Lohmannstr. 2, D-56626 Andernach, Germany
| | - Werner Weitschies
- Institute of Pharmacy, Department of Biopharmaceutics & Pharmaceutical Technology, Center of Drug Absorption and Transport, University of Greifswald, Felix-Hausdorff-Str. 3, 17487 Greifswald, Germany.
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13
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Weitschies W, Müller L, Grimm M, Koziolek M. Ingestible devices for studying the gastrointestinal physiology and their application in oral biopharmaceutics. Adv Drug Deliv Rev 2021; 176:113853. [PMID: 34192551 DOI: 10.1016/j.addr.2021.113853] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 06/22/2021] [Accepted: 06/23/2021] [Indexed: 12/17/2022]
Abstract
Ingestible sensor systems are unique tools for obtaining physiological data from an undisturbed gastrointestinal tract. Since their dimensions correspond to monolithic oral dosage forms, such as enteric coated tablets or hydrogel matrix tablets, they also allow insights into the physiological conditions experienced by non-disintegrating dosage forms on their way through the gastrointestinal tract. In this work, the different ingestible sensor systems which can be used for this purpose are described and their potential applications as well as difficulties and pitfalls with respect to their use are presented. It is also highlighted how the data on transit times, pH, temperature and pressure as well as the data from different animal models commonly used in drug product development such as dogs and pigs have contributed to a deeper mechanistic understanding of oral drug delivery.
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Affiliation(s)
- Werner Weitschies
- Institute of Pharmacy, Center of Drug Absorption and Transport, University of Greifswald, Greifswald, Germany.
| | - Laura Müller
- Institute of Pharmacy, Center of Drug Absorption and Transport, University of Greifswald, Greifswald, Germany
| | - Michael Grimm
- Institute of Pharmacy, Center of Drug Absorption and Transport, University of Greifswald, Greifswald, Germany
| | - Mirko Koziolek
- NCE Formulation Sciences, AbbVie Deutschland GmbH & Co. KG, Ludwigshafen, Germany
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14
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Sclocco R, Nguyen C, Staley R, Fisher H, Mendez A, Velez C, Kettner NW, Kuo B, Napadow V. Non-uniform gastric wall kinematics revealed by 4D Cine magnetic resonance imaging in humans. Neurogastroenterol Motil 2021; 33:e14146. [PMID: 33797166 DOI: 10.1111/nmo.14146] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Revised: 02/24/2021] [Accepted: 03/16/2021] [Indexed: 12/16/2022]
Abstract
BACKGROUND Assessment of gastric function in humans has relied on modalities with varying degrees of invasiveness, which are usually limited to the evaluation of single aspects of gastric function, thus requiring patients to undergo a number of often invasive tests for a full clinical understanding. Therefore, the development of a non-invasive tool able to concurrently assess multiple aspects of gastric function is highly desirable for both research and clinical assessments of gastrointestinal (GI) function. Recently, technological advances in magnetic resonance imaging (MRI) have provided new tools for dynamic (or "cine") body imaging. Such approaches can be extended to GI applications. METHODS In the present work, we propose a non-invasive assessment of gastric function using a four-dimensional (4D, volumetric cine imaging), free-breathing MRI sequence with gadolinium-free contrast enhancement achieved through a food-based meal. In healthy subjects, we successfully estimated multiple parameters describing gastric emptying, motility, and peristalsis propagation patterns. KEY RESULTS Our data demonstrated non-uniform kinematics of the gastric wall during peristaltic contraction, highlighting the importance of using volumetric data to derive motility measures. CONCLUSIONS & INFERENCES MRI has the potential of becoming an important clinical and gastric physiology research tool, providing objective parameters for the evaluation of impaired gastric function.
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Affiliation(s)
- Roberta Sclocco
- Department of Radiology, Harvard Medical School, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, USA.,Department of Gastroenterology, Harvard Medical School, Center for Neurointestinal Health, Massachusetts General Hospital, Boston, MA, USA.,Department of Radiology, Logan University, Chesterfield, MO, USA
| | - Christopher Nguyen
- Department of Radiology, Harvard Medical School, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, USA.,Harvard Medical School, Cardiovascular Research Center, Massachusetts General Hospital, Boston, MA, USA
| | - Rowan Staley
- Department of Radiology, Harvard Medical School, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, USA.,Department of Gastroenterology, Harvard Medical School, Center for Neurointestinal Health, Massachusetts General Hospital, Boston, MA, USA
| | - Harrison Fisher
- Department of Radiology, Harvard Medical School, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, USA
| | - April Mendez
- Department of Gastroenterology, Harvard Medical School, Center for Neurointestinal Health, Massachusetts General Hospital, Boston, MA, USA
| | - Christopher Velez
- Department of Gastroenterology, Harvard Medical School, Center for Neurointestinal Health, Massachusetts General Hospital, Boston, MA, USA
| | - Norman W Kettner
- Department of Radiology, Logan University, Chesterfield, MO, USA
| | - Braden Kuo
- Department of Gastroenterology, Harvard Medical School, Center for Neurointestinal Health, Massachusetts General Hospital, Boston, MA, USA
| | - Vitaly Napadow
- Department of Radiology, Harvard Medical School, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, USA.,Department of Radiology, Logan University, Chesterfield, MO, USA
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15
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Mennah-Govela YA, Bornhorst GM. Breakdown mechanisms of whey protein gels during dynamic in vitro gastric digestion. Food Funct 2021; 12:2112-2125. [DOI: 10.1039/d0fo03325a] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Particle geometry influenced the breakdown mechanisms impacting the pH, pepsin activity, and protein hydrolysis of whey protein gels during dynamic in vitro gastric digestion.
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Affiliation(s)
- Yamile A. Mennah-Govela
- Dept. of Biological and Agricultural Engineering
- 1308 Bainer Hall
- University of California
- Davis
- Davis
| | - Gail M. Bornhorst
- Dept. of Biological and Agricultural Engineering
- 1308 Bainer Hall
- University of California
- Davis
- Davis
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16
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Skamniotis C, Edwards CH, Bakalis S, Frost G, Charalambides M. Eulerian-Lagrangian finite element modelling of food flow-fracture in the stomach to engineer digestion. INNOV FOOD SCI EMERG 2020. [DOI: 10.1016/j.ifset.2020.102510] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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17
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Measurement of fasted state gastric antral motility before and after a standard bioavailability and bioequivalence 240 mL drink of water: Validation of MRI method against concomitant perfused manometry in healthy participants. PLoS One 2020; 15:e0241441. [PMID: 33175860 PMCID: PMC7657519 DOI: 10.1371/journal.pone.0241441] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Accepted: 10/14/2020] [Indexed: 12/26/2022] Open
Abstract
Objective The gastrointestinal environment in which drug products need to disintegrate before the drug can dissolve and be absorbed has not been studied in detail due to limitations, especially invasiveness of existing techniques. Minimal in vivo data is available on undisturbed gastrointestinal motility to improve relevance of predictive dissolution models and in silico tools such as physiologically-based pharmacokinetic models. Recent advances in magnetic resonance imaging methods could provide novel data and insights that can be used as a reference to validate and, if necessary, optimize these models. The conventional method for measuring gastrointestinal motility is via a manometric technique involving intubation. Nevertheless, it is feasible to measure gastrointestinal motility with magnetic resonance imaging. The aim of this study was is to develop and validate a magnetic resonance imaging method using the most recent semi-automated analysis method against concomitant perfused manometry method. Material and methods Eighteen healthy fasted participants were recruited for this study. The participants were intubated with a water-perfused manometry catheter. Subsequently, stomach motility was assessed by cine-MRI acquired at intervals, of 3.5min sets, at coronal oblique planes through the abdomen and by simultaneous water perfused manometry, before and after administration of a standard bioavailability / bioequivalence 8 ounces (~240mL) drink of water. The magnetic resonance imaging motility images were analysed using Spatio-Temporal Motility analysis STMM techniques. The area under the curve of the gastric motility contractions was calculated for each set and compared between techniques. The study visit was then repeated one week later. Results Data from 15 participants was analysed. There was a good correlation between the MRI antral motility plots area under the curve and corresponding perfused manometry motility area under the curve (r = 0.860) during both antral contractions and quiescence. Conclusion Non-invasive dynamic magnetic resonance imaging of gastric antral motility coupled with recently developed, semi-automated magnetic resonance imaging data processing techniques correlated well with simultaneous, ‘gold standard’ water perfused manometry. This will be particularly helpful for research purposes related to oral absorption where the absorption of a drug is highly depending on the underlying gastrointestinal processes such as gastric emptying, gastrointestinal motility and availability of residual fluid volumes. Clinical trial This trial was registered at ClinicalTrials.gov as NCT03191045.
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18
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A comparison of different physical stomach models and an analysis of shear stresses and strains in these system. Food Res Int 2020; 135:109296. [DOI: 10.1016/j.foodres.2020.109296] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Revised: 04/21/2020] [Accepted: 05/04/2020] [Indexed: 01/28/2023]
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19
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Klemm L, Seydewitz R, Borsdorf M, Siebert T, Böl M. On a coupled electro-chemomechanical model of gastric smooth muscle contraction. Acta Biomater 2020; 109:163-181. [PMID: 32294551 DOI: 10.1016/j.actbio.2020.04.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2019] [Revised: 03/31/2020] [Accepted: 04/02/2020] [Indexed: 12/13/2022]
Abstract
The stomach is a central organ in the gastrointestinal tract that performs a variety of functions, in which the spatio-temporal organisation of active smooth muscle contraction in the stomach wall (SW) is highly regulated. In the present study, a three-dimensional model of the gastric smooth muscle contraction is presented, including the mechanical contribution of the mucosal and muscular layer of the SW. Layer-specific and direction-dependent model parameters for the active and passive stress-stretch characteristics of the SW were determined experimentally using porcine smooth muscle strips. The electrical activation of the smooth muscle cells (SMC) due to the pacemaker activity of the interstitial cells of Cajal (ICC) is modelled by using FitzHugh-Nagumo-type equations, which simulate the typical ICC and SMC slow wave behaviour. The calcium dynamic in the SMC depends on the SMC membrane potential via a gaussian function, while the chemo-mechanical coupling in the SMC is modelled via an extended Hai-Murphy model. This cascade is coupled with an additional mechano-electrical feedback-mechanism, taking into account the mechanical response of the ICC and SMC due to stretch of the SW. In this way the relaxation responses of the fundus to accommodate incoming food, as well as the typical peristaltic contraction waves in the antrum for mixing and transport of the chyme, have been well replicated in simulations performed at the whole organ level. STATEMENT OF SIGNIFICANCE: In this article, a novel three-dimensional electro-chemomechanical model of the gastric smooth muscle contraction is presented. The propagating waves of electrical membrane potential in the network ofinterstitial cells of Cajal (ICC) and smooth muscle cells (SMC) lead to a global pattern of change in the calciumdynamics inside the SMC. Taking additionally into account the mechanical response of the ICC and SMC due to stretch of the stomach wall, also referred to as mechanical feedback-mechanism, the result is a complex spatio-temporal regulation of the active contraction and relaxation of the gastric smooth muscle tissue. Being a firstapproach, in future view such a three-dimensional model can give an insight into the complexload transferring system of the stomach wall, as well as into the electro-chemomechanicalcoupling process underlying smooth muscle contraction in health and disease.
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Affiliation(s)
- Lisa Klemm
- Institute of Solid Mechanics, Technische Universität Braunschweig, Braunschweig D-38106, Germany
| | - Robert Seydewitz
- Institute of Solid Mechanics, Technische Universität Braunschweig, Braunschweig D-38106, Germany
| | - Mischa Borsdorf
- Institute of Sport and Motion Science, University of Stuttgart, Stuttgart D-70569, Germany
| | - Tobias Siebert
- Institute of Sport and Motion Science, University of Stuttgart, Stuttgart D-70569, Germany
| | - Markus Böl
- Institute of Solid Mechanics, Technische Universität Braunschweig, Braunschweig D-38106, Germany.
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20
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Ishida S, Miyagawa T, O'Grady G, Cheng LK, Imai Y. Quantification of gastric emptying caused by impaired coordination of pyloric closure with antral contraction: a simulation study. J R Soc Interface 2019; 16:20190266. [PMID: 31387481 PMCID: PMC6731493 DOI: 10.1098/rsif.2019.0266] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Accepted: 07/04/2019] [Indexed: 12/18/2022] Open
Abstract
Proper coordination of gastric motor functions is required for healthy gastric emptying. However, pyloric function may be impaired by functional disorders or surgical procedures. Here, we show how coordination between pyloric closure and antral contraction affects the emptying of liquid contents. We numerically simulated fluid dynamics using an anatomically realistic gastrointestinal geometry. Peristaltic contractions in the proximal stomach resulted in gastric emptying at a rate of 3-8 ml min-1. When the pylorus was unable to close, the emptying rate increased to 10-30 ml min-1, and instantaneous retrograde flow from the duodenum to the antrum occurred during antral relaxation. Rapid emptying occurred if the pylorus began to open during the terminal antral contraction, and the emptying rate was negative if the pylorus only opened during the antral relaxation phase. Our results showed that impaired coordination between antral contraction and pyloric closure can result in delayed gastric emptying, rapid gastric emptying and bile reflux.
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Affiliation(s)
- Shunichi Ishida
- Graduate School of Engineering, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan
| | - Taimei Miyagawa
- Graduate School of Science and Technology, Hirosaki University, Hirosaki, Japan
| | - Gregory O'Grady
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Leo K. Cheng
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
- Riddet Institute, Palmerston North, New Zealand
| | - Yohsuke Imai
- Graduate School of Engineering, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan
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21
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Li Y, Fortner L, Kong F. Development of a Gastric Simulation Model (GSM) incorporating gastric geometry and peristalsis for food digestion study. Food Res Int 2019; 125:108598. [PMID: 31554041 DOI: 10.1016/j.foodres.2019.108598] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 07/23/2019] [Accepted: 07/30/2019] [Indexed: 01/14/2023]
Abstract
There has been growing interest in developing in vitro gastrointestinal models as alternatives to in vivo tests, which is challenging ethically and financially. An in vitro Gastric Simulation Model (GSM) was developed to reproduce the geometry and motility of human stomach. The peristalsis was generated by a series of syringes squeezing a latex chamber pneumatically. In particular, the distribution, amplitude and frequency of contractions demonstrated similar patterns as in human gastric conditions. The breakdown kinetics and size distribution of sausage particles during the digestion were investigated in GSM to demonstrate the effect of the contraction force. Furthermore, the gastric emptying of water-soluble nutrient (methylene blue) and nondigestible solids (amberlite beads) was investigated. The results indicated that the viscosity of the gastric digesta significantly affected the local flow and emptying behavior of nutrients and solids. This study illustrated the capability of GSM to recreate the transient physiological conditions and dynamic flow of gastric contents due to its specificity of geometry and contraction patterns. The new model can be used to investigate the influence of food matrix and physiological conditions, including gastric secretion and contraction forces on transit and digestion of foods in the stomach.
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Affiliation(s)
- Yiwen Li
- Department of Food Science and Technology, The University of Georgia, Athens, GA 30602, USA
| | - Lewis Fortner
- Instrument Design & Fabrication Shop, the University of Georgia, Athens, GA 30605, USA
| | - Fanbin Kong
- Department of Food Science and Technology, The University of Georgia, Athens, GA 30602, USA.
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22
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Parker H, Hoad CL, Tucker E, Costigan C, Marciani L, Gowland P, Fox M. Gastric motor and sensory function in health assessed by magnetic resonance imaging: Establishment of reference intervals for the Nottingham test meal in healthy subjects. Neurogastroenterol Motil 2018; 30:e13463. [PMID: 30216596 DOI: 10.1111/nmo.13463] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Revised: 08/08/2018] [Accepted: 08/13/2018] [Indexed: 02/08/2023]
Abstract
BACKGROUND Current investigations of gastric emptying rarely identify the cause of symptoms or provide a definitive diagnosis in patients with dyspepsia. This study assessed gastric function by magnetic resonance imaging (MRI) using the modular "Nottingham test meal" (NTM) in healthy volunteers (HVs). METHODS The NTM comprises (a) 400 mL liquid nutrient (0.75 kcal/mL) labeled with Gadolinium-DOTA and (b) an optional solid component (12 agar-beads [0 kcal]). Filling sensations were documented. MRI measurements of gastric volume, emptying, contraction wave frequency, and secretion were obtained using validated methods. KEY RESULTS Gastric function was measured in a population of 73 HVs stratified for age and sex. NTM induced moderate satiety and fullness. Labeled fluid was observed in the small bowel in all subjects after meal ingestion ("early-phase" GE). Secretion was rapid such that postprandial gastric content volume was often greater than meal volume (GCV0 > 400 mL), and there was increasing dilution of the meal during the study (P < 0.001). Gastric half-time was median 66-minutes (95% reference interval 35 to 161-minutes ["late-phase" GE]). The number of intact agar beads in the stomach was 7/12 (58%) at 60-minutes and 1/12 (8%) at 120-minutes. Age, bodyweight and sex had measurable effects on gastric function; however, these were small compared to inter-individual variation for most metrics. CONCLUSIONS AND INFERENCES Reference intervals are presented for MRI measurements of gastric function assessed for the mixed liquid/solid NTM. Studies in patients will determine which metrics are of clinical value and also whether the reference intervals presented here offer optimal diagnostic sensitivity and specificity.
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Affiliation(s)
- Helen Parker
- NIHR Nottingham BRC, Nottingham University Hospitals NHS Trust and the University of Nottingham, Nottingham, UK.,Nottingham Digestive Diseases Centre, School of Medicine, University of Nottingham, Nottingham, UK.,Zürich Neurogastroenterology and Motility Research Group, Department of Gastroenterology and Hepatology, University Hospital Zürich, Zürich, Switzerland.,Institute of Health and Society, Newcastle University, Newcastle upon Tyne, UK
| | - Caroline L Hoad
- NIHR Nottingham BRC, Nottingham University Hospitals NHS Trust and the University of Nottingham, Nottingham, UK.,Nottingham Digestive Diseases Centre, School of Medicine, University of Nottingham, Nottingham, UK.,Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, UK
| | - Emily Tucker
- NIHR Nottingham BRC, Nottingham University Hospitals NHS Trust and the University of Nottingham, Nottingham, UK.,Nottingham Digestive Diseases Centre, School of Medicine, University of Nottingham, Nottingham, UK
| | - Carolyn Costigan
- NIHR Nottingham BRC, Nottingham University Hospitals NHS Trust and the University of Nottingham, Nottingham, UK.,Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, UK
| | - Luca Marciani
- NIHR Nottingham BRC, Nottingham University Hospitals NHS Trust and the University of Nottingham, Nottingham, UK.,Nottingham Digestive Diseases Centre, School of Medicine, University of Nottingham, Nottingham, UK.,Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, UK
| | - Penny Gowland
- Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, UK
| | - Mark Fox
- NIHR Nottingham BRC, Nottingham University Hospitals NHS Trust and the University of Nottingham, Nottingham, UK.,Nottingham Digestive Diseases Centre, School of Medicine, University of Nottingham, Nottingham, UK.,Zürich Neurogastroenterology and Motility Research Group, Department of Gastroenterology and Hepatology, University Hospital Zürich, Zürich, Switzerland
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23
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Menys A, Saliakellis E, Borrelli O, Thapar N, Taylor SA, Watson T. The evolution of magnetic resonance enterography in the assessment of motility disorders in children. Eur J Radiol 2018; 107:105-110. [PMID: 30292253 DOI: 10.1016/j.ejrad.2018.08.017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 08/02/2018] [Accepted: 08/20/2018] [Indexed: 12/11/2022]
Abstract
Gastrointestinal symptoms including constipation, diarrhoea, pain and bloating represent some of the most common clinical problems for patients. These symptoms can often be managed with cheap, widely available medication or will spontaneously resolve. However, for many patients, chronic GI symptoms persist and frequently come to dominate their lives. At one end of the spectrum there is Inflammatory Bowel Disease (IBD) with a clearly defined but expensive treatment pathway. Contrasting with this is Irritable Bowel Syndrome (IBS), likely a collection of pathologies, has a poorly standardised pathway with unsatisfactory clinical outcomes. Managing GI symptoms in adult populations is a challenge. The clinical burden of gastrointestinal disease is also prevalent in paediatric populations and perhaps even harder to treat. In this review we explore some of the recent advances in magnetic resonance imaging (MRI) to study the gastrointestinal tract. Complex in both its anatomical structure and its physiology we are likely missing key physiological markers of disease through relying on symptomatic descriptors of gut function. Using MRI we might be able to characterise previously opaque processes, such as non-propulsive contractility, that could lead to changes in how we understand even common symptoms like constipation. This review explores recent advances in the field in adult populations and examines how this safe, objective and increasingly available modality might be applied to paediatric populations.
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Affiliation(s)
- A Menys
- Centre for Medical Imaging, UCL, London, UK.
| | | | - O Borrelli
- Great Ormond Street Hospital, London, UK
| | - N Thapar
- Great Ormond Street Hospital, London, UK
| | - S A Taylor
- Centre for Medical Imaging, UCL, London, UK
| | - T Watson
- Great Ormond Street Hospital, London, UK
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24
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Scirocco A, Pallotta L, Rengo M, Ignazzi A, Carabotti M, Cicenia A, Vona R, Chirletti P, Maselli MA, Donghia R, Coluzzi M, Matarrese P, Silecchia G, Severi C. Myogenic oxidative imbalance interferes with antral motility in obese subjects. Dig Liver Dis 2018; 50:820-827. [PMID: 29625905 DOI: 10.1016/j.dld.2018.03.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Revised: 03/03/2018] [Accepted: 03/06/2018] [Indexed: 12/11/2022]
Abstract
BACKGROUND Obesity is characterized by a systemic low-grade chronic inflammatory oxidative condition that affects vascular and cardiac smooth muscle relaxation. In human antrum, relaxation is mediated by vasoactive intestinal peptide (VIP) through cAMP and cGMP signaling pathways. A genome-wide association study has demonstrated an association between VIP and obesity. AIM To evaluate smooth muscle activity in human obese antrum, both in in vitro preparations as well as in vivo. METHODS Antral muscle strips and cells were isolated from surgical gastric samples from obese and normal weight subjects. Muscle contraction and relaxation, myogenic oxidative stress and inflammatory status were analyzed in vitro. Distal antral motility was evaluated in vivo by magnetic resonance imaging. RESULTS Obese antral muscle cells showed an oxidative-inflammatory imbalance with overexpression of NLRP3 inflammasome, increased IL-1β secretion and caspase1-activation, and reduced antioxidant capacity associated with a myogenic motor impairment of VIP-induced relaxation. The intracellular alterations were characterized by a decreased activation of the cAMP-signaling pathway and a decreased expression of eNOS. These in vitro alterations coincided with the hindering of antral motor activity observed in vivo. Apocynin treatment, counteracting oxidative stress, reverted alterations observed in obese antral muscle. CONCLUSION Antral myogenic activity of obese subjects can be impaired by alterations of signaling pathways induced by oxidative stress.
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Affiliation(s)
- Annunziata Scirocco
- Experimental Pharmacology Laboratory, Scientific Institute of Gastroenterology "S. de Bellis", Castellana Grotte, BA, Italy
| | - Lucia Pallotta
- Department of Internal Medicine and Medical Specialties, University Sapienza, Rome, Italy
| | - Marco Rengo
- Department of Radiological Sciences, Oncology and Pathology, I.C.O.T., University Sapienza, Latina, Italy
| | - Antonia Ignazzi
- Experimental Pharmacology Laboratory, Scientific Institute of Gastroenterology "S. de Bellis", Castellana Grotte, BA, Italy
| | - Marilia Carabotti
- Department of Internal Medicine and Medical Specialties, University Sapienza, Rome, Italy
| | - Alessia Cicenia
- Department of Internal Medicine and Medical Specialties, University Sapienza, Rome, Italy
| | - Rosa Vona
- Center for Gender-Specific Medicine, Istituto Superiore di Sanità, Rome Italy
| | - Piero Chirletti
- Department of General Surgery Francesco Durante, University Sapienza, Rome, Italy
| | - Maria Antonietta Maselli
- Experimental Pharmacology Laboratory, Scientific Institute of Gastroenterology "S. de Bellis", Castellana Grotte, BA, Italy
| | - Rossella Donghia
- Experimental Pharmacology Laboratory, Scientific Institute of Gastroenterology "S. de Bellis", Castellana Grotte, BA, Italy
| | - Mariagrazia Coluzzi
- Department of Medical Surgical Sciences and Biotechnology, University Sapienza, Latina, Italy
| | - Paola Matarrese
- Center for Gender-Specific Medicine, Istituto Superiore di Sanità, Rome Italy
| | - Gianfranco Silecchia
- Department of Medical Surgical Sciences and Biotechnology, University Sapienza, Latina, Italy
| | - Carola Severi
- Department of Internal Medicine and Medical Specialties, University Sapienza, Rome, Italy.
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25
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Motion Tracking System for Robust Non-Contact Blood Perfusion Sensor. SENSORS 2018; 18:s18010277. [PMID: 29346298 PMCID: PMC5795823 DOI: 10.3390/s18010277] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Revised: 01/07/2018] [Accepted: 01/15/2018] [Indexed: 11/17/2022]
Abstract
We propose a motion-robust laser Doppler flowmetry (LDF) system that can be used as a non-contact blood perfusion sensor for medical diagnosis. Endoscopic LDF systems are typically limited in their usefulness in clinical contexts by the need for the natural organs to be immobilized, as serious motion artifacts due to the axial surface displacement can interfere with blood perfusion measurements. In our system, the focusing lens moves to track the motion of the target using a low-frequency reference signal in the optical data, enabling the suppression of these motion artifacts in the axial direction. This paper reports feasibility tests on a prototype of this system using a microfluidic phantom as a measurement target moving in the direction of the optical axis. The frequency spectra detected and the perfusion values calculated from those spectra show that the motion tracking system is capable of suppressing motion artifacts in perfusion readings. We compared the prototype LDF system’s measurements with and without motion feedback, and found that motion tracking improves the fidelity of the perfusion signal by as much as 87%.
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26
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Sicard J, Mirade PS, Portanguen S, Clerjon S, Kondjoyan A. Simulation of the gastric digestion of proteins of meat bolus using a reaction–diffusion model. Food Funct 2018; 9:6455-6469. [DOI: 10.1039/c8fo01120f] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
A mathematical model predicts the gastric digestion of meat proteins and quantifies the impacts of physiological factors on digestibility.
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Affiliation(s)
- Jason Sicard
- UR370 Qualité des Produits Animaux
- Institut National de la Recherche Agronomique (INRA)
- 63122 Saint-Genès-Champanelle
- France
| | - Pierre-Sylvain Mirade
- UR370 Qualité des Produits Animaux
- Institut National de la Recherche Agronomique (INRA)
- 63122 Saint-Genès-Champanelle
- France
| | - Stéphane Portanguen
- UR370 Qualité des Produits Animaux
- Institut National de la Recherche Agronomique (INRA)
- 63122 Saint-Genès-Champanelle
- France
| | - Sylvie Clerjon
- UR370 Qualité des Produits Animaux
- Institut National de la Recherche Agronomique (INRA)
- 63122 Saint-Genès-Champanelle
- France
| | - Alain Kondjoyan
- UR370 Qualité des Produits Animaux
- Institut National de la Recherche Agronomique (INRA)
- 63122 Saint-Genès-Champanelle
- France
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27
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A novel mechanical antrum model for the prediction of the gastroretentive potential of dosage forms. Int J Pharm 2017; 530:63-70. [DOI: 10.1016/j.ijpharm.2017.07.067] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Revised: 07/21/2017] [Accepted: 07/21/2017] [Indexed: 11/21/2022]
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28
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Van Den Abeele J, Brouwers J, Tack J, Augustijns P. Exploring the link between gastric motility and intragastric drug distribution in man. Eur J Pharm Biopharm 2017; 112:75-84. [DOI: 10.1016/j.ejpb.2016.10.027] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Revised: 10/14/2016] [Accepted: 10/28/2016] [Indexed: 02/07/2023]
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29
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Van Den Abeele J, Rubbens J, Brouwers J, Augustijns P. The dynamic gastric environment and its impact on drug and formulation behaviour. Eur J Pharm Sci 2017; 96:207-231. [DOI: 10.1016/j.ejps.2016.08.060] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Revised: 08/30/2016] [Accepted: 08/30/2016] [Indexed: 02/08/2023]
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30
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Miyagawa T, Imai Y, Ishida S, Ishikawa T. Relationship between gastric motility and liquid mixing in the stomach. Am J Physiol Gastrointest Liver Physiol 2016; 311:G1114-G1121. [PMID: 27789458 DOI: 10.1152/ajpgi.00346.2016] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Accepted: 10/25/2016] [Indexed: 01/31/2023]
Abstract
The relationship between gastric motility and the mixing of liquid food in the stomach was investigated with a numerical analysis. Three parameters of gastric motility were considered: the propagation velocity, frequency, and terminal acceleration of peristaltic contractions. We simulated gastric flow with an anatomically realistic geometric model of the stomach, considering free surface flow and moving boundaries. When a peristaltic contraction approaches the pylorus, retropulsive flow is generated in the antrum. Flow separation then occurs behind the contraction. The extent of flow separation depends on the Reynolds number (Re), which quantifies the inertial forces due to the peristaltic contractions relative to the viscous forces of the gastric contents; no separation is observed at low Re, while an increase in reattachment length is observed at high Re. While mixing efficiency is nearly constant for low Re, it increases with Re for high Re because of flow separation. Hence, the effect of the propagation velocity, frequency, or terminal acceleration of peristaltic contractions on mixing efficiency increases with Re.
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Affiliation(s)
- Taimei Miyagawa
- Graduate School of Biomedical Engineering, Tohoku University, Aoba, Sendai, Japan; and
| | - Yohsuke Imai
- School of Engineering, Tohoku University, Aoba, Sendai, Japan
| | - Shunichi Ishida
- Graduate School of Biomedical Engineering, Tohoku University, Aoba, Sendai, Japan; and
| | - Takuji Ishikawa
- Graduate School of Biomedical Engineering, Tohoku University, Aoba, Sendai, Japan; and.,School of Engineering, Tohoku University, Aoba, Sendai, Japan
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31
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Berry R, Miyagawa T, Paskaranandavadivel N, Du P, Angeli TR, Trew ML, Windsor JA, Imai Y, O'Grady G, Cheng LK. Functional physiology of the human terminal antrum defined by high-resolution electrical mapping and computational modeling. Am J Physiol Gastrointest Liver Physiol 2016; 311:G895-G902. [PMID: 27659422 PMCID: PMC5130547 DOI: 10.1152/ajpgi.00255.2016] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Accepted: 09/14/2016] [Indexed: 01/31/2023]
Abstract
High-resolution (HR) mapping has been used to study gastric slow-wave activation; however, the specific characteristics of antral electrophysiology remain poorly defined. This study applied HR mapping and computational modeling to define functional human antral physiology. HR mapping was performed in 10 subjects using flexible electrode arrays (128-192 electrodes; 16-24 cm2) arranged from the pylorus to mid-corpus. Anatomical registration was by photographs and anatomical landmarks. Slow-wave parameters were computed, and resultant data were incorporated into a computational fluid dynamics (CFD) model of gastric flow to calculate impact on gastric mixing. In all subjects, extracellular mapping demonstrated normal aboral slow-wave propagation and a region of increased amplitude and velocity in the prepyloric antrum. On average, the high-velocity region commenced 28 mm proximal to the pylorus, and activation ceased 6 mm from the pylorus. Within this region, velocity increased 0.2 mm/s per mm of tissue, from the mean 3.3 ± 0.1 mm/s to 7.5 ± 0.6 mm/s (P < 0.001), and extracellular amplitude increased from 1.5 ± 0.1 mV to 2.5 ± 0.1 mV (P < 0.001). CFD modeling using representative parameters quantified a marked increase in antral recirculation, resulting in an enhanced gastric mixing, due to the accelerating terminal antral contraction. The extent of gastric mixing increased almost linearly with the maximal velocity of the contraction. In conclusion, the human terminal antral contraction is controlled by a short region of rapid high-amplitude slow-wave activity. Distal antral wave acceleration plays a major role in antral flow and mixing, increasing particle strain and trituration.
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Affiliation(s)
- Rachel Berry
- 1Auckland Bioengineering Institute, University of Auckland, Aukland, New Zealand;
| | - Taimei Miyagawa
- 2Department of Biomedical Engineering, Tohoku University, Sendai, Japan;
| | | | - Peng Du
- 1Auckland Bioengineering Institute, University of Auckland, Aukland, New Zealand;
| | - Timothy R. Angeli
- 1Auckland Bioengineering Institute, University of Auckland, Aukland, New Zealand;
| | - Mark L. Trew
- 1Auckland Bioengineering Institute, University of Auckland, Aukland, New Zealand;
| | - John A. Windsor
- 3Department of Surgery, University of Auckland, Auckland, New Zealand;
| | - Yohsuke Imai
- 4School of Engineering, Tohoku University, Sendai, Japan; and
| | - Gregory O'Grady
- 1Auckland Bioengineering Institute, University of Auckland, Aukland, New Zealand; ,3Department of Surgery, University of Auckland, Auckland, New Zealand;
| | - Leo K. Cheng
- 1Auckland Bioengineering Institute, University of Auckland, Aukland, New Zealand; ,5Department of Surgery, Vanderbilt University, Nashville, Tennessee
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32
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Development of an advanced in vitro model of the stomach and its evaluation versus human gastric physiology. Food Res Int 2016. [DOI: 10.1016/j.foodres.2016.01.030] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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33
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Buisman WJ, Mauritz FA, Westerhuis WE, Gilja OH, van der Zee DC, van Herwaarden-Lindeboom MYA. Evaluation of Gastric Volumes: Comparison of 3-D Ultrasound and Magnetic Resonance Imaging. ULTRASOUND IN MEDICINE & BIOLOGY 2016; 42:1423-1430. [PMID: 27067418 DOI: 10.1016/j.ultrasmedbio.2016.01.031] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Revised: 01/14/2016] [Accepted: 01/23/2016] [Indexed: 06/05/2023]
Abstract
To investigate gastric accommodation, accurate measurements of gastric volumes are necessary. An excellent technique to measure gastric volumes is dynamic magnetic resonance imaging (MRI). Unfortunately, dynamic MRI is expensive and not always available. A new 3-D ultrasound (US) method using a matrix transducer was developed to measure gastric volumes. In this prospective study, 14 healthy volunteers underwent a dynamic MRI and a 3-D US. Gastric volumes were calculated with intra-gastric liquid content and total gastric volume. Mean postprandial liquid gastric content was 397 ± 96.5 mL. Mean volume difference was 1.0 mL with limits of agreement of -8.9 to 10.9 mL. When gastric air was taken into account, mean total gastric volume was 540 ± 115.4 mL SD. Mean volume difference was 2.3 mL with limits of agreement of -21.1 to 26.4 mL. The matrix 3-D US showed excellent agreement with dynamic MRI. Therefore matrix 3-D US is a reliable alternative to measure gastric volumes.
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Affiliation(s)
- Wijnand J Buisman
- Department of Pediatric Surgery, University Medical Center Utrecht, Utrecht, The Netherlands.
| | - Femke A Mauritz
- Department of Pediatric Surgery, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Wouter E Westerhuis
- Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Odd Helge Gilja
- National Centre for Ultrasound in Gastroenterology, Haukeland University Hospital, Bergen, Norway; Department of Clinical Medicine, University of Bergen, Bergen, Norway
| | - David C van der Zee
- Department of Pediatric Surgery, University Medical Center Utrecht, Utrecht, The Netherlands
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34
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Gharibans AA, Kim S, Kunkel D, Coleman TP. High-Resolution Electrogastrogram: A Novel, Noninvasive Method for Determining Gastric Slow-Wave Direction and Speed. IEEE Trans Biomed Eng 2016; 64:807-815. [PMID: 27305668 DOI: 10.1109/tbme.2016.2579310] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Despite its simplicity and noninvasiveness, the use of the electrogastrogram (EGG) remains limited in clinical practice for assessing gastric disorders. Recent studies have characterized the occurrence of spatial gastric myoelectric abnormalities that are ignored by typical approaches relying on time-frequency analysis of single channels. In this paper we present the highresolution (HR) EGG, which utilizes an array of electrodes to estimate the direction and speed of gastric slow-waves. The approach was verified on a forward electrophysiology model of the stomach, demonstrating that an accurate assessment of slow-wave propagation can be made. Furthermore, we tested the methodology on eight healthy adults and calculated propagation directions (181 ± 29 degrees) and speeds (3.7 ± 0.5 mm/s) that are consistent with serosal recordings of slow-waves described in the literature. By overcoming the limitations of current methods, HR-EGG is a fully automated tool that may unveil new classes of gastric abnormalities. This could lead to a better diagnosis of diseases and inspire novel drugs and therapies, ultimately improving clinical outcomes.
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35
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Koziolek M, Grimm M, Schneider F, Jedamzik P, Sager M, Kühn JP, Siegmund W, Weitschies W. Navigating the human gastrointestinal tract for oral drug delivery: Uncharted waters and new frontiers. Adv Drug Deliv Rev 2016; 101:75-88. [PMID: 27037063 DOI: 10.1016/j.addr.2016.03.009] [Citation(s) in RCA: 113] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Revised: 03/17/2016] [Accepted: 03/20/2016] [Indexed: 02/07/2023]
Abstract
Many concepts of oral drug delivery are based on our comprehension of human gastrointestinal physiology. Unfortunately, we tend to oversimplify the complex interplay between the various physiological factors in the human gut and, in particular, the dynamics of these transit conditions to which oral dosage forms are exposed. Recent advances in spatial and temporal resolution of medical instrumentation as well as improved access to these technologies have facilitated clinical trials to characterize the dynamic processes within the human gastrointestinal tract. These studies have shown that highly relevant parameters such as fluid volumes, dosage form movement, and pH values in the lumen of the upper GI tract are very dynamic. As a result of these new insights into the human gastrointestinal environment, some common concepts and ideas of oral drug delivery are no longer valid and have to be reviewed in order to ensure efficacy and safety of oral drug therapy.
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36
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El Khoury D, Goff HD, Anderson GH. The role of alginates in regulation of food intake and glycemia: a gastroenterological perspective. Crit Rev Food Sci Nutr 2016; 55:1406-24. [PMID: 24915329 DOI: 10.1080/10408398.2012.700654] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Regulation of food intake through modulation of gastrointestinal responses to ingested foods is an ever-growing component of the therapeutic approaches targeting the obesity epidemic. Alginates, viscous and gel-forming soluble fibers isolated from the cell wall of brown seaweeds and some bacteria, are recently receiving considerable attention because of their potential role in satiation, satiety, and food intake regulation in the short term. Enhancement of gastric distension, delay of gastric emptying, and attenuation of postprandial glucose responses may constitute the basis of their physiological benefits. Offering physical, chemical, sensorial, and physiological advantages over other viscous and gel-forming fibers, alginates constitute promising functional food ingredients for the food industry. Therefore, the current review explores the role of alginates in food intake and glycemic regulation, their underlying modes of action and their potential in food applications.
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Affiliation(s)
- D El Khoury
- a Department of Nutritional Sciences, Faculty of Medicine, University of Toronto , Toronto , M5S 3E2 , ON , Canada
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37
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Gopirajah R, Anandharamakrishnan C. Advancement of Imaging and Modeling Techniques for Understanding Gastric Physical Forces on Food. FOOD ENGINEERING REVIEWS 2016. [DOI: 10.1007/s12393-016-9140-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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38
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Bornhorst GM, Gouseti O, Wickham MS, Bakalis S. Engineering Digestion: Multiscale Processes of Food Digestion. J Food Sci 2016; 81:R534-43. [DOI: 10.1111/1750-3841.13216] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2015] [Accepted: 12/16/2015] [Indexed: 11/26/2022]
Affiliation(s)
- Gail M. Bornhorst
- Dept. of Biological and Agricultural EngineeringUniv. of California Davis, 1 Shields Avenue Davis Calif. U.S.A
| | - Ourania Gouseti
- School of Chemical EngineeringUniv. of Birmingham Birmingham UK
| | | | - Serafim Bakalis
- School of Chemical EngineeringUniv. of Birmingham Birmingham UK
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39
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Gopirajah R, Raichurkar KP, Wadhwa R, Anandharamakrishnan C. The glycemic response to fibre rich foods and their relationship with gastric emptying and motor functions: an MRI study. Food Funct 2016; 7:3964-72. [DOI: 10.1039/c6fo00659k] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The chief motor functions of human stomach, namely receiving, storing, mixing and emptying, influence the absorption of ingested food and hence determine the glycemic response to the meal.
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Affiliation(s)
- R. Gopirajah
- Centre for Food Nanotechnology
- Department of Food Engineering
- CSIR-Central Food Technological Research Institute
- Mysore-570 020
- India
| | | | - Rajkumar Wadhwa
- Radiology Department
- Vikram Hospital Pvt. Ltd
- Mysore 570020
- India
| | - C. Anandharamakrishnan
- Centre for Food Nanotechnology
- Department of Food Engineering
- CSIR-Central Food Technological Research Institute
- Mysore-570 020
- India
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40
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Sheybani A, Menias CO, Luna A, Fowler KJ, Hara AK, Silva AC, Yano M, Sandrasegaran K. MRI of the stomach: a pictorial review with a focus on oncological applications and gastric motility. ACTA ACUST UNITED AC 2015; 40:907-30. [PMID: 25261256 DOI: 10.1007/s00261-014-0251-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The purpose of this pictorial review is to demonstrate gastric pathology seen on magnetic resonance imaging (MRI) and discuss the essential MRI sequences for the evaluation of benign and malignant gastric pathologies. Common tumors of the stomach, polyposis syndromes, iatrogenic conditions, as well as other conditions of the stomach will be reviewed. The utility of MRI in the evaluation of patients with gastric malignancies and disorders of gastric motility will also be discussed.
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Affiliation(s)
- Arman Sheybani
- Department of Radiology, University of Illinois Hospital and Health Sciences System, University of Illinois at Chicago, 1740 W Taylor Street, Suite 2511, Chicago, IL, 60612, USA,
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41
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Lammers WJ. Inhomogeneities in the propagation of the slow wave in the stomach. Neurogastroenterol Motil 2015; 27:1349-53. [PMID: 26407766 DOI: 10.1111/nmo.12671] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Accepted: 08/11/2015] [Indexed: 01/07/2023]
Abstract
The propagation of the slow wave in the stomach and its role in inducing sweeping peristaltic contractions toward the pylorus, essential for a proper digestion and emptying, have been studied for many years. Irregularities in the timing or in the pattern of propagation of the slow wave have been known to induce various gastric malfunctions and, recently, several types of gastric dysrhythmias have been described which could lead to gastric contraction abnormalities. In this study, Du et al. have analyzed the disturbances caused by a simple transmural incision in a human stomach, performed to obtain a biopsy of the muscle, on the propagation pattern of the slow wave. In addition, they show that such an incision may by itself also induce new types of gastric dysrhythmias. These results are important in demonstrating that the function of the stomach can easily be disturbed by such procedures. This mini-review describes several ways in which inhomogeneities in propagation may affect the conduction pattern of the slow wave, including the genesis of several dysrhythmias, and what is currently known about their impact on gastric contraction and digestion.
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Affiliation(s)
- W J Lammers
- formerly Department of Physiology, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
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42
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Ferrua MJ, Singh RP. Computational modelling of gastric digestion: current challenges and future directions. Curr Opin Food Sci 2015. [DOI: 10.1016/j.cofs.2015.06.005] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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43
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Arrieta J, Cartwright JHE, Gouillart E, Piro N, Piro O, Tuval I. Geometric Mixing, Peristalsis, and the Geometric Phase of the Stomach. PLoS One 2015; 10:e0130735. [PMID: 26154384 PMCID: PMC4496066 DOI: 10.1371/journal.pone.0130735] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2013] [Accepted: 05/23/2015] [Indexed: 12/29/2022] Open
Abstract
Mixing fluid in a container at low Reynolds number— in an inertialess environment—is not a trivial task. Reciprocating motions merely lead to cycles of mixing and unmixing, so continuous rotation, as used in many technological applications, would appear to be necessary. However, there is another solution: movement of the walls in a cyclical fashion to introduce a geometric phase. We show using journal-bearing flow as a model that such geometric mixing is a general tool for using deformable boundaries that return to the same position to mix fluid at low Reynolds number. We then simulate a biological example: we show that mixing in the stomach functions because of the “belly phase,” peristaltic movement of the walls in a cyclical fashion introduces a geometric phase that avoids unmixing.
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Affiliation(s)
- Jorge Arrieta
- Mediterranean Institute for Advanced Studies (CSIC-UIB), E-07190 Esporles, Spain
- Área de Mecánica de Fluidos, Universidad Carlos III de Madrid, E-28911, Leganés, Spain
| | - Julyan H. E. Cartwright
- Instituto Andaluz de Ciencias de la Tierra, CSIC–Universidad de Granada, Campus Fuentenueva, E-18071 Granada, Spain
| | - Emmanuelle Gouillart
- Surface du Verre et Interfaces, UMR 125 CNRS/Saint-Gobain, 93303 Aubervilliers, France
| | - Nicolas Piro
- École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
- * E-mail:
| | - Oreste Piro
- Departament de Física, Universitat de les Illes Balears, E-07071 Palma de Mallorca, Spain
| | - Idan Tuval
- Mediterranean Institute for Advanced Studies (CSIC-UIB), E-07190 Esporles, Spain
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44
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Hoad CL, Parker H, Hudders N, Costigan C, Cox EF, Perkins AC, Blackshaw PE, Marciani L, Spiller RC, Fox MR, Gowland PA. Measurement of gastric meal and secretion volumes using magnetic resonance imaging. Phys Med Biol 2015; 60:1367-83. [PMID: 25592405 PMCID: PMC4502365 DOI: 10.1088/0031-9155/60/3/1367] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
MRI can assess multiple gastric functions without ionizing radiation. However, time consuming image acquisition and analysis of gastric volume data, plus confounding of gastric emptying measurements by gastric secretions mixed with the test meal have limited its use to research centres. This study presents an MRI acquisition protocol and analysis algorithm suitable for the clinical measurement of gastric volume and secretion volume. Reproducibility of gastric volume measurements was assessed using data from 10 healthy volunteers following a liquid test meal with rapid MRI acquisition within one breath-hold and semi-automated analysis. Dilution of the ingested meal with gastric secretion was estimated using a respiratory-triggered T1 mapping protocol. Accuracy of the secretion volume measurements was assessed using data from 24 healthy volunteers following a mixed (liquid/solid) test meal with MRI meal volumes compared to data acquired using gamma scintigraphy (GS) on the same subjects studied on a separate study day. The mean ± SD coefficient of variance between 3 observers for both total gastric contents (including meal, secretions and air) and just the gastric contents (meal and secretion only) was 3 ± 2% at large gastric volumes (>200 ml). Mean ± SD secretion volumes post meal ingestion were 64 ± 51 ml and 110 ± 40 ml at 15 and 75 min, respectively. Comparison with GS meal volumes, showed that MRI meal only volume (after correction for secretion volume) were similar to GS, with a linear regression gradient ± std err of 1.06 ± 0.10 and intercept -11 ± 24 ml. In conclusion, (i) rapid volume acquisition and respiratory triggered T₁ mapping removed the requirement to image during prolonged breath-holds (ii) semi-automatic analysis greatly reduced the time required to derive measurements and (iii) correction for secretion volumes provided accurate assessment of gastric meal volumes and emptying. Together these features provide the scientific basis of a protocol which would be suitable in clinical practice.
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Affiliation(s)
- C L Hoad
- Sir Peter Mansfield Magnetic Resonance Centre, University of Nottingham, University Park, Nottingham, NG7 2RD UK. NIHR Biomedical Research Unit in Gastrointestinal and Liver Diseases, Nottingham University Hospitals Trust and the University of Nottingham, UK
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45
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On the kinematics and efficiency of advective mixing during gastric digestion – A numerical analysis. J Biomech 2014; 47:3664-73. [DOI: 10.1016/j.jbiomech.2014.09.033] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Revised: 09/05/2014] [Accepted: 09/25/2014] [Indexed: 11/19/2022]
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46
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Development of a bio-relevant dissolution test device simulating mechanical aspects present in the fed stomach. Eur J Pharm Sci 2014; 57:250-6. [DOI: 10.1016/j.ejps.2013.09.004] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Revised: 09/02/2013] [Accepted: 09/06/2013] [Indexed: 01/02/2023]
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47
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Bornhorst GM, Paul Singh R. Gastric Digestion In Vivo and In Vitro: How the Structural Aspects of Food Influence the Digestion Process. Annu Rev Food Sci Technol 2014; 5:111-32. [DOI: 10.1146/annurev-food-030713-092346] [Citation(s) in RCA: 121] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Gail M. Bornhorst
- Department of Biological and Agricultural Engineering, University of California, Davis, California 95616; ,
| | - R. Paul Singh
- Department of Biological and Agricultural Engineering, University of California, Davis, California 95616; ,
- Riddet Institute, Massey University, Palmerston North 4442, New Zealand
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48
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Yoshimoto K, Yamada K, Watabe K, Takeda M, Nishimura T, Kido M, Nagakura T, Takahashi H, Nishida T, Iijima H, Tsujii M, Takehara T, Ohno Y. Gastric Contraction Imaging System Using a 3-D Endoscope. IEEE JOURNAL OF TRANSLATIONAL ENGINEERING IN HEALTH AND MEDICINE-JTEHM 2014; 2:1800208. [PMID: 27170867 PMCID: PMC4861546 DOI: 10.1109/jtehm.2014.2298852] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Revised: 11/08/2013] [Accepted: 12/09/2013] [Indexed: 11/06/2022]
Abstract
This paper presents a gastric contraction imaging system for assessment of gastric motility using a 3-D endoscope. Gastrointestinal diseases are mainly based on morphological abnormalities. However, gastrointestinal symptoms are sometimes apparent without visible abnormalities. One of the major factors for these diseases is abnormal gastrointestinal motility. For assessment of gastric motility, a gastric motility imaging system is needed. To assess the dynamic motility of the stomach, the proposed system measures 3-D gastric contractions derived from a 3-D profile of the stomach wall obtained with a developed 3-D endoscope. After obtaining contraction waves, their frequency, amplitude, and speed of propagation can be calculated using a Gaussian function. The proposed system was evaluated for 3-D measurements of several objects with known geometries. The results showed that the surface profiles could be obtained with an error of [Formula: see text] of the distance between two different points on images. Subsequently, we evaluated the validity of a prototype system using a wave simulated model. In the experiment, the amplitude and position of waves could be measured with 1-mm accuracy. The present results suggest that the proposed system can measure the speed and amplitude of contractions. This system has low invasiveness and can assess the motility of the stomach wall directly in a 3-D manner. Our method can be used for examination of gastric morphological and functional abnormalities.
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Affiliation(s)
- Kayo Yoshimoto
- Osaka University Division of Health Sciences Graduate School of Medicine Osaka Japan 565-0871
| | - Kenji Yamada
- Osaka University Division of Health Sciences Graduate School of Medicine Osaka Japan 565-0871
| | - Kenji Watabe
- Osaka University Department of Gastroenterology and Hepatology Graduate School of Medicine Osaka Japan 565-0871
| | - Maki Takeda
- Osaka University Division of Health Sciences Graduate School of Medicine Osaka Japan 565-0871
| | - Takahiro Nishimura
- Osaka University Division of Health Sciences Graduate School of Medicine Osaka Japan 565-0871
| | - Michiko Kido
- Osaka University Division of Health Sciences Graduate School of Medicine Osaka Japan 565-0871
| | - Toshiaki Nagakura
- Osaka Electro-Communication University Department of Biomedical Engineering Graduate School of Biomedical Engineering Osaka Japan 575-0063
| | - Hideya Takahashi
- Osaka University Division of Health Sciences Graduate School of Medicine Osaka Japan 565-0871
| | - Tsutomu Nishida
- Osaka University Department of Gastroenterology and Hepatology Graduate School of Medicine Osaka Japan 565-0871
| | - Hideki Iijima
- Osaka University Department of Gastroenterology and Hepatology Graduate School of Medicine Osaka Japan 565-0871
| | - Masahiko Tsujii
- Osaka University Department of Gastroenterology and Hepatology Graduate School of Medicine Osaka Japan 565-0871
| | - Tetsuo Takehara
- Osaka University Department of Gastroenterology and Hepatology Graduate School of Medicine Osaka Japan 565-0871
| | - Yuko Ohno
- Osaka University Division of Health Sciences Graduate School of Medicine Osaka Japan 565-0871
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49
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Koziolek M, Garbacz G, Neumann M, Weitschies W. Simulating the Postprandial Stomach: Physiological Considerations for Dissolution and Release Testing. Mol Pharm 2013; 10:1610-22. [DOI: 10.1021/mp300604u] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Mirko Koziolek
- Institute of Pharmacy, Department
of Biopharmaceutics and Pharmaceutical Technology, Center of Drug
Absorption and Transport, University of Greifswald, Felix-Hausdorff-Strasse
3, 17487 Greifswald, Germany
| | - Grzegorz Garbacz
- Physiolution GmbH, Walther-Rathenau-Strasse
49a, 17489 Greifswald, Germany
| | - Marco Neumann
- Institute of Pharmacy, Department
of Biopharmaceutics and Pharmaceutical Technology, Center of Drug
Absorption and Transport, University of Greifswald, Felix-Hausdorff-Strasse
3, 17487 Greifswald, Germany
| | - Werner Weitschies
- Institute of Pharmacy, Department
of Biopharmaceutics and Pharmaceutical Technology, Center of Drug
Absorption and Transport, University of Greifswald, Felix-Hausdorff-Strasse
3, 17487 Greifswald, Germany
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50
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Imai Y, Kobayashi I, Ishida S, Ishikawa T, Buist M, Yamaguchi T. Antral recirculation in the stomach during gastric mixing. Am J Physiol Gastrointest Liver Physiol 2013; 304:G536-42. [PMID: 23275619 DOI: 10.1152/ajpgi.00350.2012] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
We investigate flow in the stomach during gastric mixing using a numerical simulation with an anatomically realistic geometry and free-surface flow modeling. Because of momentum differences between greater and lesser curvatures during peristaltic contractions, time-averaged recirculation is generated in the antrum, with retropulsive flow away from the pylorus and compensation flow along the greater curvature toward the pylorus. Gastric content in the distal stomach is continuously transported to the distal antrum by the forward flow of antral recirculation, and it is then mixed by the backward retropulsive flow. Hence, the content inside the antral recirculation is well mixed independently of initial location, whereas the content outside the recirculation is poorly mixed. Free-surface modeling enables us to analyze the effects of posture on gastric mixing. In the upright, prone, and right lateral positions, most of the antrum is filled with content, and the content is well mixed by antral recirculation. In contrast, in the supine and left lateral positions, most of the content is located outside antral recirculation, which results in poor mixing. The curved, twisted shape of the stomach substantially supports gastric mixing in fluid mechanical terms.
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Affiliation(s)
- Yohsuke Imai
- Department of Bioengineering and Robotics, Tohoku University, 6-6-01 Aoba, Aoba, Sendai 980-8579, Japan.
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