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Sharma S, Buist ML. Comparing finite viscoelastic constitutive relations and variational principles in modeling gastrointestinal soft tissue deformation. J Mech Behav Biomed Mater 2024; 155:106560. [PMID: 38744120 DOI: 10.1016/j.jmbbm.2024.106560] [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] [Received: 12/18/2023] [Revised: 04/20/2024] [Accepted: 04/23/2024] [Indexed: 05/16/2024]
Abstract
The mechanical attributes of soft tissues within the gastrointestinal (GI) tract are crucial for the effective operation of the GI system, and alterations in these properties may play a role in motility-related disorders. Various constitutive modeling approaches have been suggested to comprehend the response of soft tissues to diverse loading conditions. Among these, hyperelastic constitutive models based on finite elasticity have gained popularity. However, these models fall short in capturing rate- and time-dependent tissue properties. In contrast, finite viscoelastic models offer a solution to overcome these limitations. Nevertheless, the development of a suitable finite viscoelastic model, coupled with a variational formulation for efficient finite element (FE) implementation, remains an ongoing challenge. This study aims to address this gap by developing diverse finite viscoelastic constitutive relations and applying them to characterize soft tissue. Furthermore, the research explores the creation of compressible, nearly incompressible, and incompressible versions of viscoelastic constitutive relations, along with their variational formulation, to facilitate efficient FE implementation. The proposed model demonstrates remarkable accuracy in replicating experimental results, achieving an R2 value exceeding 0.99.
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Affiliation(s)
- Swati Sharma
- Department of Biomedical Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117583, Singapore
| | - Martin Lindsay Buist
- Department of Biomedical Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117583, Singapore.
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2
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Woo M, Pandey A, Li D, Buresi M, Nasser Y, Andrews CN. Constipated patients with functional defecatory disorder have secondary rectal hyposensitivity due to altered rectal biomechanics. J Gastroenterol Hepatol 2024; 39:1082-1087. [PMID: 38418424 DOI: 10.1111/jgh.16517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 12/06/2023] [Accepted: 02/03/2024] [Indexed: 03/01/2024]
Abstract
BACKGROUND AND AIM Rectal hyposensitivity (RH) is common in constipation and often coexists with functional defecatory disorder (FDD). Rectal sensory thresholds are routinely evaluated with the anorectal manometry probe; however, the gold standard for the assessment of rectal sensitivity is with a barostat, use of which is limited by time constraints and availability. A novel rapid barostat bag (RBB) may facilitate measurements of rectal sensitivity. The aim is to evaluate the relationship between RH (measured by the RBB) and FDD (defined as any minor disorder of rectoanal coordination by the London classification) in constipated patients. METHODS Consecutive constipated patients referred for anorectal function testing underwent anorectal manometry with the 3D-HDAM probe as well as rectal sensation testing with the RBB pump. RH was defined by volume to first sensation >30%, urge to defecate >80%, or discomfort >100% (normalized to rectal capacity). RESULTS Fifty-three percent of constipated patients had RH. Patients with FDD had a significantly increased volume to first sensation (134.5 mL vs 102.0, P = 0.02), urge to defecate (187.0 mL vs 149.0, P = 0.04), and rectal capacity (253.5 mL vs 209.0, P = 0.04) compared to constipated patients without FDD. There was no difference in normalized sensory thresholds (percent of rectal capacity) nor the prevalence of hyposensitivity to each sensory threshold nor overall hyposensitivity. CONCLUSION Patients with FDD, when measured with the RBB, have increased sensory thresholds on volumetric distension, but RH was not observed when sensory threshold volume were normalized to rectal capacity. This may reflect "secondary" RH due to altered rectal biomechanics.
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Affiliation(s)
- Matthew Woo
- Division of Gastroenterology and Hepatology, University of Calgary Cumming School of Medicine, Calgary, Alberta, Canada
| | - Armaan Pandey
- Division of Gastroenterology and Hepatology, University of Calgary Cumming School of Medicine, Calgary, Alberta, Canada
| | - Dorothy Li
- Division of Gastroenterology and Hepatology, University of Calgary Cumming School of Medicine, Calgary, Alberta, Canada
| | - Michelle Buresi
- Division of Gastroenterology and Hepatology, University of Calgary Cumming School of Medicine, Calgary, Alberta, Canada
| | - Yasmin Nasser
- Division of Gastroenterology and Hepatology, University of Calgary Cumming School of Medicine, Calgary, Alberta, Canada
| | - Christopher N Andrews
- Division of Gastroenterology and Hepatology, University of Calgary Cumming School of Medicine, Calgary, Alberta, Canada
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Sharma S, Buist ML. The origin of intraluminal pressure waves in gastrointestinal tract. Med Biol Eng Comput 2024:10.1007/s11517-024-03128-6. [PMID: 38787486 DOI: 10.1007/s11517-024-03128-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Accepted: 05/10/2024] [Indexed: 05/25/2024]
Abstract
The gastrointestinal (GI) peristalsis is an involuntary wave-like contraction of the GI wall that helps to propagate food along the tract. Many GI diseases, e.g., gastroparesis, are known to cause motility disorders in which the physiological contractile patterns of the wall get disrupted. Therefore, to understand the pathophysiology of these diseases, it is necessary to understand the mechanism of GI motility. We present a coupled electromechanical model to describe the mechanism of GI motility and the transduction pathway of cellular electrical activities into mechanical deformation and the generation of intraluminal pressure (IP) waves in the GI tract. The proposed model consolidates a smooth muscle cell (SMC) model, an actin-myosin interaction model, a hyperelastic constitutive model, and a Windkessel model to construct a coupled model that can describe the origin of peristaltic contractions in the intestine. The key input to the model is external electrical stimuli, which are converted into mechanical contractile waves in the wall. The model recreated experimental observations efficiently and was able to establish a relationship between change in luminal volume and pressure with the compliance of the GI wall and the peripheral resistance to bolus flow. The proposed model will help us understand the GI tract's function in physiological and pathophysiological conditions.
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Affiliation(s)
- Swati Sharma
- Department of Biomedical Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore, 117583, Singapore
| | - Martin L Buist
- Department of Biomedical Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore, 117583, Singapore.
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Durcan C, Hossain M, Chagnon G, Perić D, Girard E. Mechanical experimentation of the gastrointestinal tract: a systematic review. Biomech Model Mechanobiol 2024; 23:23-59. [PMID: 37935880 PMCID: PMC10901955 DOI: 10.1007/s10237-023-01773-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Accepted: 09/10/2023] [Indexed: 11/09/2023]
Abstract
The gastrointestinal (GI) organs of the human body are responsible for transporting and extracting nutrients from food and drink, as well as excreting solid waste. Biomechanical experimentation of the GI organs provides insight into the mechanisms involved in their normal physiological functions, as well as understanding of how diseases can cause disruption to these. Additionally, experimental findings form the basis of all finite element (FE) modelling of these organs, which have a wide array of applications within medicine and engineering. This systematic review summarises the experimental studies that are currently in the literature (n = 247) and outlines the areas in which experimentation is lacking, highlighting what is still required in order to more fully understand the mechanical behaviour of the GI organs. These include (i) more human data, allowing for more accurate modelling for applications within medicine, (ii) an increase in time-dependent studies, and (iii) more sophisticated in vivo testing methods which allow for both the layer- and direction-dependent characterisation of the GI organs. The findings of this review can also be used to identify experimental data for the readers' own constitutive or FE modelling as the experimental studies have been grouped in terms of organ (oesophagus, stomach, small intestine, large intestine or rectum), test condition (ex vivo or in vivo), number of directions studied (isotropic or anisotropic), species family (human, porcine, feline etc.), tissue condition (intact wall or layer-dependent) and the type of test performed (biaxial tension, inflation-extension, distension (pressure-diameter), etc.). Furthermore, the studies that investigated the time-dependent (viscoelastic) behaviour of the tissues have been presented.
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Affiliation(s)
- Ciara Durcan
- Zienkiewicz Centre for Modelling, Data and AI, Faculty of Science and Engineering, Swansea University, Swansea, SA1 8EN, UK
- Université Grenoble Alpes, CNRS, UMR 5525, VetAgro Sup, Grenoble INP, TIMC, 38000, Grenoble, France
| | - Mokarram Hossain
- Zienkiewicz Centre for Modelling, Data and AI, Faculty of Science and Engineering, Swansea University, Swansea, SA1 8EN, UK.
| | - Grégory Chagnon
- Université Grenoble Alpes, CNRS, UMR 5525, VetAgro Sup, Grenoble INP, TIMC, 38000, Grenoble, France
| | - Djordje Perić
- Zienkiewicz Centre for Modelling, Data and AI, Faculty of Science and Engineering, Swansea University, Swansea, SA1 8EN, UK
| | - Edouard Girard
- Université Grenoble Alpes, CNRS, UMR 5525, VetAgro Sup, Grenoble INP, TIMC, 38000, Grenoble, France
- Laboratoire d'Anatomie des Alpes Françaises, Université Grenoble Alpes, Grenoble, France
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Subashi E, Segars P, Veeraraghavan H, Deasy J, Tyagi N. A model for gastrointestinal tract motility in a 4D imaging phantom of human anatomy. Med Phys 2023; 50:3066-3075. [PMID: 36808107 PMCID: PMC10561541 DOI: 10.1002/mp.16305] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 01/26/2023] [Accepted: 01/29/2023] [Indexed: 02/23/2023] Open
Abstract
BACKGROUND Gastrointestinal (GI) tract motility is one of the main sources for intra/inter-fraction variability and uncertainty in radiation therapy for abdominal targets. Models for GI motility can improve the assessment of delivered dose and contribute to the development, testing, and validation of deformable image registration (DIR) and dose-accumulation algorithms. PURPOSE To implement GI tract motion in the 4D extended cardiac-torso (XCAT) digital phantom of human anatomy. MATERIALS AND METHODS Motility modes that exhibit large amplitude changes in the diameter of the GI tract and may persist over timescales comparable to online adaptive planning and radiotherapy delivery were identified based on literature research. Search criteria included amplitude changes larger than planning risk volume expansions and durations of the order of tens of minutes. The following modes were identified: peristalsis, rhythmic segmentation, high amplitude propagating contractions (HAPCs), and tonic contractions. Peristalsis and rhythmic segmentations were modeled by traveling and standing sinusoidal waves. HAPCs and tonic contractions were modeled by traveling and stationary Gaussian waves. Wave dispersion in the temporal and spatial domain was implemented by linear, exponential, and inverse power law functions. Modeling functions were applied to the control points of the nonuniform rational B-spline surfaces defined in the reference XCAT library. GI motility was combined with the cardiac and respiratory motions available in the standard 4D-XCAT phantom. Default model parameters were estimated based on the analysis of cine MRI acquisitions in 10 patients treated in a 1.5T MR-linac. RESULTS We demonstrate the ability to generate realistic 4D multimodal images that simulate GI motility combined with respiratory and cardiac motion. All modes of motility, except tonic contractions, were observed in the analysis of our cine MRI acquisitions. Peristalsis was the most common. Default parameters estimated from cine MRI were used as initial values for simulation experiments. It is shown that in patients undergoing stereotactic body radiotherapy for abdominal targets, the effects of GI motility can be comparable or larger than the effects of respiratory motion. CONCLUSION The digital phantom provides realistic models to aid in medical imaging and radiation therapy research. The addition of GI motility will further contribute to the development, testing, and validation of DIR and dose accumulation algorithms for MR-guided radiotherapy.
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Affiliation(s)
- Ergys Subashi
- Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, New York
| | - Paul Segars
- Department of Radiology, Duke University Medical Center, Durham, North Carolina
| | - Harini Veeraraghavan
- Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, New York
| | - Joseph Deasy
- Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, New York
| | - Neelam Tyagi
- Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, New York
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Monaco A, Choi D, Uzun S, Maitland A, Riley B. Association of mast-cell-related conditions with hypermobile syndromes: a review of the literature. Immunol Res 2022; 70:419-431. [PMID: 35449490 PMCID: PMC9022617 DOI: 10.1007/s12026-022-09280-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Accepted: 04/11/2022] [Indexed: 11/26/2022]
Abstract
Ehlers-Danlos syndrome (EDS) is a group of related connective tissue disorders consisting of 13 subtypes, each with its own unique phenotypic and genetic variation. The overlap of symptoms and multitude of EDS variations makes it difficult for patients to achieve a diagnosis early in the course of their disease. The most common form, hypermobile type EDS (hEDS) and its variant, hypermobile spectrum disorder (HSD), are correlated with rheumatologic and inflammatory conditions. Evidence is still needed to determine the pathophysiology of hEDS; however, the association among these conditions and their prevalence in hEDS/HSD may be explained through consideration of persistent chronic inflammation contributing to a disruption of the connective tissue. Aberrant mast cell activation has been shown to play a role in disruption of connective tissue integrity through activity of its mediators including histamine and tryptase which affects multiple organ systems resulting in mast cell activation disorders (MCAD). The overlap of findings associated with MCAD and the immune-mediated and rheumatologic conditions in patients with hEDS/HSD may provide an explanation for the relationship among these conditions and the presence of chronic inflammatory processes in these patients. It is clear that a multidisciplinary approach is required for the treatment of patients with EDS. However, it is also important for clinicians to consider the summarized symptoms and MCAD-associated characteristics in patients with multiple complaints as possible manifestations of connective tissue disorders, in order to potentially aid in establishing an early diagnosis of EDS.
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Affiliation(s)
- Ashley Monaco
- Department of Family Medicine, NYIT College of Osteopathic Medicine, Northern Boulevard, Old Westbury, NY, 11568, USA.
| | - Diane Choi
- Department of Family Medicine, NYIT College of Osteopathic Medicine, Northern Boulevard, Old Westbury, NY, 11568, USA
| | - Serife Uzun
- Department of Family Medicine, NYIT College of Osteopathic Medicine, Northern Boulevard, Old Westbury, NY, 11568, USA
| | - Anne Maitland
- Division of Medicine, Icahn School of Medicine at Mount Sinai, Gustave L. Levy Place, New York, NY, 10029, USA
| | - Bernadette Riley
- Department of Family Medicine, NYIT College of Osteopathic Medicine, Northern Boulevard, Old Westbury, NY, 11568, USA
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Verkuijl SJ, Trzpis M, Broens PMA. The anorectal defaecation reflex: a prospective intervention study. Colorectal Dis 2022; 24:845-853. [PMID: 35194918 PMCID: PMC9541108 DOI: 10.1111/codi.16101] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 01/30/2022] [Accepted: 02/14/2022] [Indexed: 12/13/2022]
Abstract
AIM Our hypothesis is that there may be a neural pathway with sensory afferent neurons in the anal canal that leads to rectal contraction to assist defaecation. We aimed to compare rectal motility between healthy participants with or without anal anaesthesia. METHOD This prospective intervention study consisted of two test sessions: a baseline session followed by an identical second session. During each session we performed the anal electrosensitivity test, the rectoanal inhibitory reflex test and rapid phasic barostat distensions. Prior to the second session, participants were randomly assigned to receive either a local anal anaesthetic or a placebo. RESULTS We included 23 healthy participants aged 21.1 ± 0.5 years, 13 of whom received an anal anaesthetic and 10 a placebo. All participants showed a transient rectal contraction during the first test session, which decreased significantly after anal anaesthesia (18.6 ml vs. 4.9 ml, p = 0.019). The maximum rectal contraction was comparable to the baseline results in the placebo group. Furthermore, the electrosensitivity at the highest centimetre of the anal canal correlated with the maximum rectal contraction (r = -0.452, p = 0.045). CONCLUSION All healthy study participants display an involuntary, reproducible rectal reflex contraction that appears to be innervated by afferent nerves in the proximal anal canal. The rectal reflex contraction appears to play a role in defaecation and we therefore refer to this phenomenon as the anorectal defaecation reflex. Knowledge of the anorectal defaecation reflex may have consequences for the diagnostics and treatment of constipation.
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Affiliation(s)
- Sanne J. Verkuijl
- Department of SurgeryAnorectal Physiology LaboratoryUniversity of GroningenUniversity Medical Center GroningenGroningenThe Netherlands,Department of SurgeryDivision of Paediatric SurgeryUniversity of GroningenUniversity Medical Center GroningenGroningenThe Netherlands
| | - Monika Trzpis
- Department of SurgeryAnorectal Physiology LaboratoryUniversity of GroningenUniversity Medical Center GroningenGroningenThe Netherlands
| | - Paul M. A. Broens
- Department of SurgeryAnorectal Physiology LaboratoryUniversity of GroningenUniversity Medical Center GroningenGroningenThe Netherlands,Department of SurgeryDivision of Paediatric SurgeryUniversity of GroningenUniversity Medical Center GroningenGroningenThe Netherlands
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Biomechanical Properties of Strictures in Crohn’s Disease: Can Dynamic Contrast-Enhanced Ultrasonography and Magnetic Resonance Enterography Predict Stiffness? Diagnostics (Basel) 2022; 12:diagnostics12061370. [PMID: 35741180 PMCID: PMC9221822 DOI: 10.3390/diagnostics12061370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Revised: 05/24/2022] [Accepted: 05/31/2022] [Indexed: 11/17/2022] Open
Abstract
Strictures and abdominal pain often complicate Crohn’s disease (CD). The primary aim was to explore whether parameters obtained by preoperative contrast-enhanced (CE) ultrasonography (US) and dynamic CE MR Enterography (DCE-MRE) of strictures associates with biomechanical properties. CD patients undergoing elective small intestinal surgery were preoperatively examined with DCE-MRE and CEUS. The excised intestine was distended utilizing a pressure bag. Luminal and outer bowel wall cross-sectional areas were measured with US. The circumferential stricture stiffness (Young’s modulus E) was computed. Stiffness was associated with the initial slope of enhancement on DCE-MRE (ρ = 0.63, p = 0.007), reflecting active disease, but lacked association with CEUS parameters. For structural imaging parameters, inflammation and stricture stiffness were associated with prestenotic dilatation on US (τb = 0.43, p = 0.02) but not with MRE (τb = 0.01, p = 1.0). Strictures identified by US were stiffer, 16.8 (14.0–20.1) kPa, than those graded as no or uncertain strictures, 12.6 (10.5–15.1) kPa, p = 0.02. MRE global score (activity) was associated with E (ρ = 0.55, p = 0.018). Elastography did not correlate with circumferential stiffness. We conclude that increasing activity defined by the initial slope of enhancement on DCE-MRE and MRE global score were associated with stricture stiffness. Prestenotic dilatation on US could be a potential biomarker of CD small intestinal stricture stiffness.
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Patel B, Gizzi A, Hashemi J, Awakeem Y, Gregersen H, Kassab G. Biomechanical constitutive modeling of the gastrointestinal tissues: a systematic review. MATERIALS & DESIGN 2022; 217:110576. [PMID: 35935127 PMCID: PMC9351365 DOI: 10.1016/j.matdes.2022.110576] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The gastrointestinal (GI) tract is a continuous channel through the body that consists of the esophagus, the stomach, the small intestine, the large intestine, and the rectum. Its primary functions are to move the intake of food for digestion before storing and ultimately expulsion of feces. The mechanical behavior of GI tissues thus plays a crucial role for GI function in health and disease. The mechanical properties are characterized by a biomechanical constitutive model, which is a mathematical representation of the relation between load and deformation in a tissue. Hence, validated biomechanical constitutive models are essential to characterize and simulate the mechanical behavior of the GI tract. Here, a systematic review of these constitutive models is provided. This review is limited to studies where a model of the strain energy function is proposed to characterize the stress-strain relation of a GI tissue. Several needs are identified for more advanced modeling including: 1) Microstructural models that provide actual structure-function relations; 2) Validation of coupled electro-mechanical models accounting for active muscle contractions; 3) Human data to develop and validate models. The findings from this review provide guidelines for using existing constitutive models as well as perspective and directions for future studies.
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Affiliation(s)
- Bhavesh Patel
- California Medical Innovations Institute, 11107 Roselle St, San Diego, CA 92121, USA
| | - Alessio Gizzi
- Department of Engineering, Campus Bio-Medico University of Rome, Via A. del Portillo 21, 00128 Rome, IT
| | - Javad Hashemi
- California Medical Innovations Institute, 11107 Roselle St, San Diego, CA 92121, USA
| | - Yousif Awakeem
- California Medical Innovations Institute, 11107 Roselle St, San Diego, CA 92121, USA
| | - Hans Gregersen
- California Medical Innovations Institute, 11107 Roselle St, San Diego, CA 92121, USA
| | - Ghassan Kassab
- California Medical Innovations Institute, 11107 Roselle St, San Diego, CA 92121, USA
- Corresponding author , Tel: 001-858-249-7400, Fax: 001-858-249-7419, (Ghassan Kassab)
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Biomechanical analysis of sheep oesophagus subjected to biaxial testing including hyperelastic constitutive model fitting. Heliyon 2022; 8:e09312. [PMID: 35615432 PMCID: PMC9124710 DOI: 10.1016/j.heliyon.2022.e09312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Revised: 01/11/2022] [Accepted: 04/19/2022] [Indexed: 11/23/2022] Open
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Mercado-Perez A, Beyder A. Gut feelings: mechanosensing in the gastrointestinal tract. Nat Rev Gastroenterol Hepatol 2022; 19:283-296. [PMID: 35022607 PMCID: PMC9059832 DOI: 10.1038/s41575-021-00561-y] [Citation(s) in RCA: 43] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 11/22/2021] [Indexed: 12/11/2022]
Abstract
The primary function of the gut is to procure nutrients. Synchronized mechanical activities underlie nearly all its endeavours. Coordination of mechanical activities depends on sensing of the mechanical forces, in a process called mechanosensation. The gut has a range of mechanosensory cells. They function either as specialized mechanoreceptors, which convert mechanical stimuli into coordinated physiological responses at the organ level, or as non-specialized mechanosensory cells that adjust their function based on the mechanical state of their environment. All major cell types in the gastrointestinal tract contain subpopulations that act as specialized mechanoreceptors: epithelia, smooth muscle, neurons, immune cells, and others. These cells are tuned to the physical properties of the surrounding tissue, so they can discriminate mechanical stimuli from the baseline mechanical state. The importance of gastrointestinal mechanosensation has long been recognized, but the latest discoveries of molecular identities of mechanosensors and technical advances that resolve the relevant circuitry have poised the field to make important intellectual leaps. This Review describes the mechanical factors relevant for normal function, as well as the molecules, cells and circuits involved in gastrointestinal mechanosensing. It concludes by outlining important unanswered questions in gastrointestinal mechanosensing.
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Affiliation(s)
- Arnaldo Mercado-Perez
- Enteric NeuroScience Program (ENSP), Division of Gastroenterology & Hepatology, Mayo Clinic, Rochester, MN, USA
- Medical Scientist Training Program (MSTP), Mayo Clinic, Rochester, MN, USA
| | - Arthur Beyder
- Enteric NeuroScience Program (ENSP), Division of Gastroenterology & Hepatology, Mayo Clinic, Rochester, MN, USA.
- Department of Physiology & Biomedical Engineering, Mayo Clinic, Rochester, MN, USA.
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Durcan C, Hossain M, Chagnon G, Perić D, Bsiesy L, Karam G, Girard E. Experimental investigations of the human oesophagus: anisotropic properties of the embalmed muscular layer under large deformation. Biomech Model Mechanobiol 2022; 21:1169-1186. [PMID: 35477829 PMCID: PMC9045687 DOI: 10.1007/s10237-022-01583-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2022] [Accepted: 03/31/2022] [Indexed: 11/24/2022]
Abstract
The oesophagus is a primarily mechanical organ whose material characterisation would aid in the investigation of its pathophysiology, help in the field of tissue engineering, and improve surgical simulations and the design of medical devices. However, the layer-dependent, anisotropic properties of the organ have not been investigated using human tissue, particularly in regard to its viscoelastic and stress-softening behaviour. Restrictions caused by the COVID-19 pandemic meant that fresh human tissue was not available for dissection. Therefore, in this study, the layer-specific material properties of the human oesophagus were investigated through ex vivo experimentation of the embalmed muscularis propria layer. For this, a series of uniaxial tension cyclic tests with increasing stretch levels were conducted at two different strain rates. The muscular layers from three different cadaveric specimens were tested in both the longitudinal and circumferential directions. The results displayed highly nonlinear and anisotropic behaviour, with both time- and history-dependent stress-softening. The longitudinal direction was found to be stiffer than the circumferential direction at both strain rates. Strain rate-dependent behaviour was apparent, with an increase in strain rate resulting in an increase in stiffness in both directions. Histological analysis was carried out via various staining methods; the results of which were discussed with regard to the experimentally observed stress-stretch response. Finally, the behaviour of the muscularis propria was simulated using a matrix-fibre model able to capture the various mechanical phenomena exhibited, the fibre orientation of which was driven by the histological findings of the study.
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Affiliation(s)
- Ciara Durcan
- Zienkiewicz Centre for Computational Engineering, Faculty of Science and Engineering, Swansea University, Swansea, SA1 8EN, UK.,Univ. Grenoble Alpes, CNRS, UMR 5525, VetAgro Sup, Grenoble INP, TIMC, 38000, Grenoble, France
| | - Mokarram Hossain
- Zienkiewicz Centre for Computational Engineering, Faculty of Science and Engineering, Swansea University, Swansea, SA1 8EN, UK.
| | - Grégory Chagnon
- Univ. Grenoble Alpes, CNRS, UMR 5525, VetAgro Sup, Grenoble INP, TIMC, 38000, Grenoble, France
| | - Djordje Perić
- Zienkiewicz Centre for Computational Engineering, Faculty of Science and Engineering, Swansea University, Swansea, SA1 8EN, UK
| | - Lara Bsiesy
- Univ. Grenoble Alpes, CNRS, UMR 5525, VetAgro Sup, Grenoble INP, TIMC, 38000, Grenoble, France
| | - Georges Karam
- Univ. Grenoble Alpes, CNRS, UMR 5525, VetAgro Sup, Grenoble INP, TIMC, 38000, Grenoble, France
| | - Edouard Girard
- Univ. Grenoble Alpes, CNRS, UMR 5525, VetAgro Sup, Grenoble INP, TIMC, 38000, Grenoble, France.,Laboratoire d'Anatomie des Alpes Françaises, Univ. Grenoble Alpes, Grenoble, France
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Costa M, Wiklendt L, Hibberd T, Dinning P, Spencer NJ, Brookes S. Analysis of Intestinal Movements with Spatiotemporal Maps: Beyond Anatomy and Physiology. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2022; 1383:271-294. [PMID: 36587166 DOI: 10.1007/978-3-031-05843-1_26] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Over 150 years ago, methods for quantitative analysis of gastrointestinal motor patterns first appeared. Graphic representations of physiological variables were recorded with the kymograph after the mid-1800s. Changes in force or length of intestinal muscles could be quantified, however most recordings were limited to a single point along the digestive tract.In parallel, photography and cinematography with X-Rays visualised changes in intestinal shape, but were hard to quantify. More recently, the ability to record physiological events at many sites along the gut in combination with computer processing allowed construction of spatiotemporal maps. These included diameter maps (DMaps), constructed from video recordings of intestinal movements and pressure maps (PMaps), constructed using data from high-resolution manometry catheters. Combining different kinds of spatiotemporal maps revealed additional details about gut wall status, including compliance, which relates forces to changes in length. Plotting compliance values along the intestine enabled combined DPMaps to be constructed, which can distinguish active contractions and relaxations from passive changes. From combinations of spatiotemporal maps, it is possible to deduce the role of enteric circuits and pacemaker cells in the generation of complex motor patterns. Development and application of spatiotemporal methods to normal and abnormal motor patterns in animals and humans is ongoing, with further technical improvements arising from their combination with impedance manometry, magnetic resonance imaging, electrophysiology, and ultrasonography.
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Affiliation(s)
- Marcello Costa
- College of Medicine and Public Health, Department of Human Physiology, Flinders University, Bedford Park, SA, Australia.
| | - Luke Wiklendt
- Department of Gastroenterology and Surgery, Flinders Medical Centre, Bedford Park, SA, Australia
| | - Tim Hibberd
- College of Medicine and Public Health, Department of Human Physiology, Flinders University, Bedford Park, SA, Australia
| | - Phil Dinning
- Department of Gastroenterology and Surgery, Flinders Medical Centre, Bedford Park, SA, Australia
| | - Nick J Spencer
- College of Medicine and Public Health, Department of Human Physiology, Flinders University, Bedford Park, SA, Australia
| | - Simon Brookes
- College of Medicine and Public Health, Department of Human Physiology, Flinders University, Bedford Park, SA, Australia
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14
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Yang Y, Paivinen P, Xie C, Krup AL, Makela TP, Mostov KE, Reiter JF. Ciliary Hedgehog signaling patterns the digestive system to generate mechanical forces driving elongation. Nat Commun 2021; 12:7186. [PMID: 34893605 PMCID: PMC8664829 DOI: 10.1038/s41467-021-27319-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Accepted: 11/08/2021] [Indexed: 11/24/2022] Open
Abstract
How tubular organs elongate is poorly understood. We found that attenuated ciliary Hedgehog signaling in the gut wall impaired patterning of the circumferential smooth muscle and inhibited proliferation and elongation of developing intestine and esophagus. Similarly, ablation of gut-wall smooth muscle cells reduced lengthening. Disruption of ciliary Hedgehog signaling or removal of smooth muscle reduced residual stress within the gut wall and decreased activity of the mechanotransductive effector YAP. Removing YAP in the mesenchyme also reduced proliferation and elongation, but without affecting smooth muscle formation, suggesting that YAP interprets the smooth muscle-generated force to promote longitudinal growth. Additionally, we developed an intestinal culture system that recapitulates the requirements for cilia and mechanical forces in elongation. Pharmacologically activating YAP in this system restored elongation of cilia-deficient intestines. Thus, our results reveal that ciliary Hedgehog signaling patterns the circumferential smooth muscle to generate radial mechanical forces that activate YAP and elongate the gut.
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Affiliation(s)
- Ying Yang
- Department of Biochemistry and Biophysics, Cardiovascular Research Institute, University of California San Francisco, San Francisco, CA, USA
| | - Pekka Paivinen
- iCAN Digital Precision Cancer Medicine Flagship, Research Programs Unit, Faculty of Medicine and HiLIFE-Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland
| | - Chang Xie
- Department of Biochemistry and Biophysics, Cardiovascular Research Institute, University of California San Francisco, San Francisco, CA, USA
| | - Alexis Leigh Krup
- Department of Biochemistry and Biophysics, Cardiovascular Research Institute, University of California San Francisco, San Francisco, CA, USA
| | - Tomi P Makela
- iCAN Digital Precision Cancer Medicine Flagship, Research Programs Unit, Faculty of Medicine and HiLIFE-Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland
| | - Keith E Mostov
- Department of Biochemistry and Biophysics, Cardiovascular Research Institute, University of California San Francisco, San Francisco, CA, USA
- Department of Anatomy, University of California San Francisco, San Francisco, CA, USA
| | - Jeremy F Reiter
- Department of Biochemistry and Biophysics, Cardiovascular Research Institute, University of California San Francisco, San Francisco, CA, USA.
- Chan Zuckerberg Biohub, San Francisco, CA, USA.
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15
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Singh G, Chanda A. Mechanical properties of whole-body soft human tissues: a review. Biomed Mater 2021; 16. [PMID: 34587593 DOI: 10.1088/1748-605x/ac2b7a] [Citation(s) in RCA: 78] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 09/29/2021] [Indexed: 11/11/2022]
Abstract
The mechanical properties of soft tissues play a key role in studying human injuries and their mitigation strategies. While such properties are indispensable for computational modelling of biological systems, they serve as important references in loading and failure experiments, and also for the development of tissue simulants. To date, experimental studies have measured the mechanical properties of peripheral tissues (e.g. skin)in-vivoand limited internal tissuesex-vivoin cadavers (e.g. brain and the heart). The lack of knowledge on a majority of human tissues inhibit their study for applications ranging from surgical planning, ballistic testing, implantable medical device development, and the assessment of traumatic injuries. The purpose of this work is to overcome such challenges through an extensive review of the literature reporting the mechanical properties of whole-body soft tissues from head to toe. Specifically, the available linear mechanical properties of all human tissues were compiled. Non-linear biomechanical models were also introduced, and the soft human tissues characterized using such models were summarized. The literature gaps identified from this work will help future biomechanical studies on soft human tissue characterization and the development of accurate medical models for the study and mitigation of injuries.
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Affiliation(s)
- Gurpreet Singh
- Centre for Biomedical Engineering, Indian Institute of Technology (IIT), Delhi, India
| | - Arnab Chanda
- Centre for Biomedical Engineering, Indian Institute of Technology (IIT), Delhi, India.,Department of Biomedical Engineering, All India Institute of Medical Sciences (AIIMS), Delhi, India
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16
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Liang YY, Shen JC, Li W. Evolution of compressive mechanical properties of early hypertrophic scar during laser treatment. J Biomech 2021; 129:110783. [PMID: 34662757 DOI: 10.1016/j.jbiomech.2021.110783] [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: 03/03/2021] [Revised: 09/24/2021] [Accepted: 09/27/2021] [Indexed: 11/27/2022]
Abstract
Laser therapy has been widely used in the treatment of hypertrophic scars (HPS), but whether the mechanical properties of HPS tissue after laser treatment can be restored to those of normal skin remains unclear. In this paper, the relationship between the evolution of compressive mechanical properties and histological changes of HPS tissues following three successive combined pulsed dye laser (PDL) and fractional CO2 laser (CO2) treatments was investigated by compression tests and histological analysis. The early HPS model of rabbit ear was established by CO2 laser ablation. The loading-unloading tests and strain creep tests under the compression forces of 1 N, 2 N, and 3 N were carried out for normal skin, untreated HPS and HPS after different treatment times, respectively. The results showed that the compression ratio λ of all tissues revealed force dependence and rose with the increasing compression force, which was similar to the trend of most biological soft tissues. The histological changes of HPSs following laser treatment have a significant influence on the compressive mechanical response. Compared with the normal skin, the toughness and anti-deformation ability of HPS reduced due to the proliferation of collagen fibers and the destruction of elastic fibers, resulting in higher energy dissipation, compression ratio λ, and stable creep rate D, and lower elastic modulus. After three successive combined PDL/ CO2 laser treatments, the compressive mechanical properties and creep properties of HPS gradually approached that of the normal skin owing to the gradual restoration of the amount and distribution of collagen and elastic fibers in HPS. The results provide a new method for evaluating the clinical efficacy of laser therapy for treatment of HPS tissue.
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Affiliation(s)
- Y Y Liang
- Tribology Research Institute, Key Laboratory for Advanced Technology of Materials of Ministry of Education, Southwest Jiaotong University, Chengdu 610031, China
| | - J C Shen
- Department of Dermatology, The Second People's Hospital of Chengdu, Chengdu, Sichuan Province 610017, China
| | - W Li
- Tribology Research Institute, Key Laboratory for Advanced Technology of Materials of Ministry of Education, Southwest Jiaotong University, Chengdu 610031, China.
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17
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Pien N, Palladino S, Copes F, Candiani G, Dubruel P, Van Vlierberghe S, Mantovani D. Tubular bioartificial organs: From physiological requirements to fabrication processes and resulting properties. A critical review. Cells Tissues Organs 2021; 211:420-446. [PMID: 34433163 DOI: 10.1159/000519207] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Accepted: 01/25/2021] [Indexed: 11/19/2022] Open
Affiliation(s)
- Nele Pien
- Laboratory for Biomaterials and Bioengineering, Canada Research Chair Tier I for the Innovation in Surgery, Department of Min-Met-Materials Engineering & Regenerative Medicine, CHU de Quebec Research Center, Laval University, Quebec City, Québec, Canada
- Polymer Chemistry & Biomaterials Group, Centre of Macromolecular Chemistry, Department of Organic and Macromolecular Chemistry, Ghent University, Ghent, Belgium
| | - Sara Palladino
- Laboratory for Biomaterials and Bioengineering, Canada Research Chair Tier I for the Innovation in Surgery, Department of Min-Met-Materials Engineering & Regenerative Medicine, CHU de Quebec Research Center, Laval University, Quebec City, Québec, Canada
- GenT Lab, Department of Chemistry, Materials and Chemical Engineering "G. Natta", Politecnico di Milano, Milan, Italy
| | - Francesco Copes
- Laboratory for Biomaterials and Bioengineering, Canada Research Chair Tier I for the Innovation in Surgery, Department of Min-Met-Materials Engineering & Regenerative Medicine, CHU de Quebec Research Center, Laval University, Quebec City, Québec, Canada
| | - Gabriele Candiani
- GenT Lab, Department of Chemistry, Materials and Chemical Engineering "G. Natta", Politecnico di Milano, Milan, Italy
| | - Peter Dubruel
- Polymer Chemistry & Biomaterials Group, Centre of Macromolecular Chemistry, Department of Organic and Macromolecular Chemistry, Ghent University, Ghent, Belgium
| | - Sandra Van Vlierberghe
- Polymer Chemistry & Biomaterials Group, Centre of Macromolecular Chemistry, Department of Organic and Macromolecular Chemistry, Ghent University, Ghent, Belgium
| | - Diego Mantovani
- Laboratory for Biomaterials and Bioengineering, Canada Research Chair Tier I for the Innovation in Surgery, Department of Min-Met-Materials Engineering & Regenerative Medicine, CHU de Quebec Research Center, Laval University, Quebec City, Québec, Canada
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18
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Helicobacter pylori Increases Gastric Compliance on Resected Stomach After Laparoscopic Sleeve Gastrectomy. Obes Surg 2021; 31:4776-4780. [PMID: 34345956 DOI: 10.1007/s11695-021-05616-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Revised: 07/14/2021] [Accepted: 07/20/2021] [Indexed: 10/20/2022]
Abstract
BACKGROUND The relationship between high body mass index (BMI) and Helicobacter pylori (HP) was reported previously. But the mechanism is not clear. We aimed to evaluate the effect of HP on gastric compliance and volumes in obese patients. MATERIALS AND METHODS One hundred fifty-nine patients who underwent sleeve gastrectomy due to morbid obesity were enrolled in the study and were divided into two groups as HP+ (n = 86) and HP- (n = 73) according to the HP status in resection materials. Demographics, pathological data, specimen sizes, volume, and compliance were retrospectively analyzed. RESULTS The median age of the study group was 34 years (17-64 years) while the median BMI was 43 kg/m2 (35-64, 3 kg/m2). Most of the patients (n = 134, 84.3%) were female. The median diameter of the widest point of the specimen was 22.5 cm (14-32 cm), and the median volume of the specimen was 790 cc (330-1920 cc). Both the diameter of the widest point and the volume of the specimens were significantly increased in the HP+ group compared to the HP- group (p < 0.001 and p = 0.017, respectively). In addition, the median compliance was 52.6 cc/mmHg, and the compliance was significantly higher (p < 0.001) in the HP+ group. There were no significant differences in specimen sizes between the two groups. CONCLUSION This is the first study showing that HP increases gastric compliance in obese patients who underwent LSG. The etiology and the effects of this increase in compliance have not been fully clarified yet. Further studies are needed to shed light on these effects.
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19
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Pan TL, Lei MC, Ng WY, Li Z. Analytical Modeling of the Interaction Between Soft Balloon-Like Actuators and Soft Tubular Environment for Gastrointestinal Inspection. Soft Robot 2021; 9:386-398. [PMID: 34143662 DOI: 10.1089/soro.2020.0159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Accessing tubular environment is critical in medicine. For example, gastrointestinal tract related cancers are the leading causes of cancer deaths globally. To diagnose and treat these cancers, clinicians need accessing the gastrointestinal tract, for example, colon and small intestine, which are soft biological tubes. Soft balloon assisted locomotion is one of the promising methods for accessing bio-duct. It has been widely used in enteroscopy and other medical devices. However, the interaction between the balloon and the soft tube is seldom studied, such as the interaction pressure and the anchoring force. In this work, we present the first modeling of the interaction between soft balloon actuators and soft tubular environment. The free inflation model of soft balloon actuators was first presented. Then a constrained inflation model of the soft balloon in a soft tube was established. Finally, the anchoring force model between the soft balloon and the soft tube was developed. On average, the mean error of the predictions in these three models is 0.228 kPa (or 3.14%), 0.56 kPa (or 7.8%), and 0.22 N (or 14.7%), respectively. In the future, these models could be used for guiding balloon-actuator designs by minimizing the interaction pressure while maintaining sufficient anchoring force during the locomotion in soft tubes.
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Affiliation(s)
- Tian Le Pan
- Department of Biomedical Engineering, The Chinese University of Hong Kong, Hong Kong
| | - Man Cheong Lei
- Chow Yuk Ho Technology Centre for Innovative Medicine, The Chinese University of Hong Kong, Hong Kong
| | - Wing Yin Ng
- Chow Yuk Ho Technology Centre for Innovative Medicine, The Chinese University of Hong Kong, Hong Kong
| | - Zheng Li
- Chow Yuk Ho Technology Centre for Innovative Medicine, The Chinese University of Hong Kong, Hong Kong.,Department of Surgery, The Chinese University of Hong Kong, Hong Kong.,Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Hong Kong.,Multiscale Medical Robotics Centre Ltd., The Chinese University of Hong Kong, Hong Kong
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20
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Cheng LK, Nagahawatte ND, Avci R, Du P, Liu Z, Paskaranandavadivel N. Strategies to Refine Gastric Stimulation and Pacing Protocols: Experimental and Modeling Approaches. Front Neurosci 2021; 15:645472. [PMID: 33967679 PMCID: PMC8100207 DOI: 10.3389/fnins.2021.645472] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Accepted: 03/22/2021] [Indexed: 12/13/2022] Open
Abstract
Gastric pacing and stimulation strategies were first proposed in the 1960s to treat motility disorders. However, there has been relatively limited clinical translation of these techniques. Experimental investigations have been critical in advancing our understanding of the control mechanisms that innervate gut function. In this review, we will discuss the use of pacing to modulate the rhythmic slow wave conduction patterns generated by interstitial cells of Cajal in the gastric musculature. In addition, the use of gastric high-frequency stimulation methods that target nerves in the stomach to either inhibit or enhance stomach function will be discussed. Pacing and stimulation protocols to modulate gastric activity, effective parameters and limitations in the existing studies are summarized. Mathematical models are useful to understand complex and dynamic systems. A review of existing mathematical models and techniques that aim to help refine pacing and stimulation protocols are provided. Finally, some future directions and challenges that should be investigated are discussed.
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Affiliation(s)
- Leo K Cheng
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand.,Department of General Surgery, Vanderbilt University Medical Center, Nashville, TN, United States.,Riddet Institute, Palmerston North, New Zealand
| | - Nipuni D Nagahawatte
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Recep Avci
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Peng Du
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Zhongming Liu
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States.,Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, MI, United States
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21
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Acharya S, Halder S, Carlson DA, Kou W, Kahrilas PJ, Pandolfino JE, Patankar NA. Assessment of esophageal body peristaltic work using functional lumen imaging probe panometry. Am J Physiol Gastrointest Liver Physiol 2021; 320:G217-G226. [PMID: 33174457 PMCID: PMC7948118 DOI: 10.1152/ajpgi.00324.2020] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The goal of this study was to conceptualize and compute measures of "mechanical work" done by the esophagus using data generated during functional lumen imaging probe (FLIP) panometry and compare work done during secondary peristalsis among patients and controls. Eighty-five individuals were evaluated with a 16-cm FLIP during sedated endoscopy, including asymptomatic controls (n = 14) and those with achalasia subtypes I, II, and III (n = 15, each); gastroesophageal reflux disease (GERD; n = 13); eosinophilic esophagitis (EoE; n = 9); and systemic sclerosis (SSc; n = 5). The FLIP catheter was positioned to have its distal segment straddling the esophagogastric junction (EGJ) during stepwise distension. Two metrics of work were assessed: "active work" (during bag volumes ≤ 40 mL where contractility generates substantial changes in lumen area) and "work capacity" (for bag volumes ≥ 60 mL when contractility cannot substantially alter the lumen area). Controls showed median [interquartile range (IQR)] of 7.3 (3.6-9.2) mJ of active work and 268.6 (225.2-332.3) mJ of work capacity. Patients with all achalasia subtypes, GERD, and SSc showed lower active work done than controls (P ≤ 0.003). Patients with achalasia subtypes I and II, GERD, and SSc had lower work capacity compared with controls (P < 0.001, 0.004, 0.04, and 0.001, respectively). Work capacity was similar between controls and patients with achalasia type III and EoE. Mechanical work of the esophagus differs between healthy controls and patient groups with achalasia, EoE, SSc, and GERD. Further studies are needed to fully explore the utility of this approach, but these work metrics would be valuable for device design (artificial esophagus), to measure the efficacy of peristalsis, to gauge the physiological state of the esophagus, and to comment on its pumping effectiveness.NEW & NOTEWORTHY Functional lumen imaging probe (FLIP) panometry assesses esophageal response to distension and provides a simultaneous assessment of pressure and dimension during contractility. This enables an objective assessment of "mechanical work" done by the esophagus. Eighty-five individuals were evaluated, and two work metrics were computed for each subject. Controls showed greater values of work compared with individuals with achalasia, gastroesophageal reflux disease (GERD), and systemic sclerosis (SSc). These values can quantify the mechanical behavior of the distal esophagus and assist in the estimation of muscular integrity.
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Affiliation(s)
- Shashank Acharya
- 1Department of Mechanical Engineering, McCormick School of Engineering, Northwestern University, Evanston, Illinois
| | - Sourav Halder
- 2Theoretical and Applied Mechanics Program, McCormick School of Engineering, Northwestern University, Evanston, Illinois
| | - Dustin A. Carlson
- 3Division of Gastroenterology and Hepatology, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois
| | - Wenjun Kou
- 3Division of Gastroenterology and Hepatology, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois
| | - Peter J. Kahrilas
- 3Division of Gastroenterology and Hepatology, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois
| | - John E. Pandolfino
- 3Division of Gastroenterology and Hepatology, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois
| | - Neelesh A. Patankar
- 1Department of Mechanical Engineering, McCormick School of Engineering, Northwestern University, Evanston, Illinois,2Theoretical and Applied Mechanics Program, McCormick School of Engineering, Northwestern University, Evanston, Illinois
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22
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Massey BT. Clinical Functional Lumen Imaging Probe Testing in Esophageal Disorders: A Need for Better Quality Evidence. Am J Gastroenterol 2020; 115:1799-1801. [PMID: 33156098 DOI: 10.14309/ajg.0000000000000974] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
In their article "Use of the Functional Lumen Imaging Probe in Clinical Esophagology," Savarino et al. report the outcomes of a Grading of Recommendations Assessment, Development, and Evaluation analysis performed by experts in the use of functional lumen imaging probe (FLIP) evaluation of esophageal disorders. For essentially all clinical indications, the recommendation for use was conditional with a very low quality of evidence. FLIP is an expensive, invasive technology examining limited aspects of esophageal function. Its role in complementing or replacing existing technology is uncertain, particularly when compared with manometric testing with additional provocative studies. Performing properly designed studies to demonstrate FLIP's true effectiveness and cost-effectiveness will be costly.
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Affiliation(s)
- Benson T Massey
- GI Manometry Laboratory, Division of Gastroenterology & Hepatology, Medical College of Wisconsin, Hub for Collaborative Medicine, Milwaukee, Wisconsin, USA
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23
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Impact of 3D-CT-Based Gastric Wall Volume on Weight Loss after Laparoscopic Sleeve Gastrectomy. Obes Surg 2020; 30:4226-4233. [DOI: 10.1007/s11695-020-04783-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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24
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Wu PI, Sloan JA, Kuribayashi S, Gregersen H. Impedance in the evaluation of the esophagus. Ann N Y Acad Sci 2020; 1481:139-153. [PMID: 32557676 DOI: 10.1111/nyas.14408] [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: 03/24/2020] [Revised: 05/09/2020] [Accepted: 05/14/2020] [Indexed: 12/16/2022]
Abstract
The aim of this paper is to review esophageal electrical impedance technologies and to discuss the use of these technologies for physiological measurements, diagnostics, and therapy of esophageal disease. In order to develop a better understanding of the pathophysiology of and improve the diagnosis of esophageal disorders, such as gastroesophageal reflux disease (GERD) and achalasia, several new diagnostic tests, including intraluminal impedance, esophageal mucosal impedance, and the functional luminal imaging probe, have been developed. These technologies have proven valuable for assessment of the esophagus in recent years. They provide information on esophageal flow properties, mucosal integrity, lumen shape, and distensibility in esophageal disorders, in particular for GERD and achalasia. Despite their promise and novel clinical studies, the potential of these technologies has been far from realized. New multidisciplinary approaches will contribute to our understanding and interpretation of esophageal impedance data and disease mechanisms.
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Affiliation(s)
- Peter I Wu
- Department of Gastroenterology and Hepatology, St George Hospital, University of New South Wales, Sydney, New South Wales, Australia
| | - Joshua A Sloan
- Division of Gastroenterology and Hepatology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Shiko Kuribayashi
- Department of Gastroenterology and Hepatology, Gunma University Hospital, Maebashi, Japan
| | - Hans Gregersen
- GIOME, Department of Surgery, The Chinese University of Hong Kong, Hong Kong, China
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25
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Panda SK, Buist ML. A viscoelastic framework for inflation testing of gastrointestinal tissue. J Mech Behav Biomed Mater 2020; 103:103569. [DOI: 10.1016/j.jmbbm.2019.103569] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2019] [Revised: 11/26/2019] [Accepted: 11/29/2019] [Indexed: 12/01/2022]
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26
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Implications of rectal preconditioning for interpretation of sensory-motor data. J Biomech 2020; 99:109541. [PMID: 31787257 DOI: 10.1016/j.jbiomech.2019.109541] [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: 09/21/2019] [Revised: 11/16/2019] [Accepted: 11/19/2019] [Indexed: 11/23/2022]
Abstract
Testing of biomechanical properties of intestine requires the tissue to be preconditioned by applying cyclic loading to obtain repeatable mechanical data. However, little is known about the mechanosensory properties during intestinal preconditioning. We aimed to study the relationship between mechanical preconditioning of the human rectum and sensory response. Three fast rectal bag distensions to the pain threshold were done in seven healthy females. A visual analog scale (VAS) was used for sensory assessment. At each distension, we determined (1) time, bag cross-sectional area (CSA), radius (r), r/r0, pressure and tension to reach VAS = 1, 3 and 5 (pain threshold); (2) the same parameters at induced contraction start; (3) CSA where the pressure started to increase (CSAP>baseline) and (4) the number of contractions. The time, CSA, r/r0 and tension to reach VAS = 1 and VAS = 3 increased from distension 1 to 3 (4.9 < F < 11.5, 0.05 > P > 0.007), primarily due to difference between the first and second distension. For VAS = 5, r/r0 was smaller in distension 3 than distension 1 (P < 0.05), whereas time, CSA and tension did not differ between distensions (P > 0.5). Compared with distension 1, CSA, r/r0 and tension at contraction start, and CSAP>baseline were bigger in distensions 2 and 3 (5.5 < F < 10.9, 0.05 > P > 0.009). The pressure to reach the VAS levels, the contraction numbers and pressure at contraction start did not differ among distensions (P > 0.6). During mechanical preconditioning, CSA, tension and deformation increased at sub-pain levels, reflecting sensory adaptation. The data point to acute remodeling of a strain-dependent mechanism in the rectal wall.
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27
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Mechanical effects of load speed on the human colon. J Biomech 2019; 91:102-108. [PMID: 31133391 DOI: 10.1016/j.jbiomech.2019.05.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Revised: 05/04/2019] [Accepted: 05/11/2019] [Indexed: 12/15/2022]
Abstract
The aim of this study was to examine the mechanical behavior of the colon using tensile tests under different loading speeds. Specimens were taken from different locations of the colonic frame from refrigerated cadavers. The specimens were submitted to uniaxial tensile tests after preconditioning using a dynamic load (1 m/s), intermediate load (10 cm/s), and quasi-static load (1 cm/s). A total of 336 specimens taken from 28 colons were tested. The stress-strain analysis for longitudinal specimens indicated a Young's modulus of 3.17 ± 2.05 MPa under dynamic loading (1 m/s), 1.74 ± 1.15 MPa under intermediate loading (10 cm/s), and 1.76 ± 1.21 MPa under quasi-static loading (1 cm/s) with p < 0.001. For the circumferential specimen, the stress-strain curves indicated a Young's modulus of 3.15 ± 1.73 MPa under dynamic loading (1 m/s), 2.14 ± 1.3 MPa under intermediate loading (10 cm/s), and 0.63 ± 1.25 MPa under quasi-static loading (1 cm/s) with p < 0.001. The curves reveal two types of behaviors of the colon: fast break behavior at high speed traction (1 m/s) and a lower break behavior for lower speeds (10 cm/s and 1 cm/s). The circumferential orientation required greater levels of stress and strain to obtain lesions than the longitudinal orientation. The presence of taeniae coli changed the mechanical response during low-speed loading. Colonic mechanical behavior varies with loading speeds with two different types of mechanical behavior: more fragile behavior under dynamic load and more elastic behavior for quasi-static load.
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Faurschou I, Ernst A, Zhao J, Liao D, Olsen LH. The biomechanical properties of the urethra in boys with hypospadias: a preliminary study. J Pediatr Urol 2019; 15:62.e1-62.e7. [PMID: 30482497 DOI: 10.1016/j.jpurol.2018.09.004] [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: 11/30/2017] [Accepted: 09/08/2018] [Indexed: 11/28/2022]
Abstract
PURPOSE The ventral aspect of the penis in boys with hypospadias is composed of dysplastic tissue of the skin and the urethra. The aim of this study was to assess the pre-operative size and biomechanical properties of urethrae in boys with and without hypospadias using a more objective catheter-based system. MATERIALS & METHODS In this non-blinded clinical observation study, the study population consisted of 19 boys with hypospadias-the case group (median age 13.9 months [range: 12.2-21.3])-and seven boys without hypospadias-the control group (median age 8.5 months [range: 3.8-18.1]). Modified measurements of impedance were used to assess the size, compliance and viscoelasticity of the urethrae under stepwise increased pressures (between 0, 40 and 60 cmH2O) using a customised Endolumenal Functional Lumen Imaging probe (EndoFLIP®). RESULTS The sizes of the urethrae in boys with hypospadias are variable but tend towards being narrower and less compliant than those of the control subjects i.e. median diameter for meatus urethra was 3.2 mm (range: 2.98-3.92) in the hypospadias group compared with 3.64 (range: 3.22-4.44) in the control group at 40 cmH2O, and the median change in diameter at meatus urethra was 0.08 mm (range: -0.02 to 0.52) in the hypospadias group compared with 0.23 mm (range: -0.02 to 0.34) when the pressure was increased from 40 to 60 cmH2O. This biomechanical analysis found that there was no significant viscoelasticity of the urethral meatus in both the groups, whereas the remainder of the urethral structure generally had viscoelastic properties in the control group, seen as a creep on the time/diameter curves (Figure). In the group of boys with hypospadias, evaluations of the urethrae revealed varying viscoelastic abilities, ranging from abilities that were comparable with those of the control subjects to no sign of viscoelasticity at all. CONCLUSIONS This study is the first to measure the biomechanical properties of the urethra in children, which might help to provide an understanding as to the structural and functional changes associated with hypospadias. The urethrae in the subjects with hypospadias were variable in diameter but tended to be narrower overall, especially in the distal portion of the urethra. Furthermore, the urethrae in boys with hypospadias were frequently less viscoelastic than those of controls. CLINICAL RELEVANCE The EndoFLIP® system may be a future way of objectively estimating the severity of a urethral obstruction and could potentially be included in the postoperative assessment of patients with signs of hampered voiding.
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Affiliation(s)
- I Faurschou
- Department of Clinical Medicine, Aarhus University, Palle Juul-Jensens Blvd. 82, DK-8200 Aarhus N, Denmark; Department of Urology, Section of Paediatric Urology, Aarhus University Hospital, Palle Juul-Jensens Blvd. 99, DK-8200 Aarhus N, Denmark.
| | - A Ernst
- Department of Urology, Section of Paediatric Urology, Aarhus University Hospital, Palle Juul-Jensens Blvd. 99, DK-8200 Aarhus N, Denmark; Department of Public Health, Section for Epidemiology, Aarhus University, Bartholins Allé 2 - Building 1260, DK-8000 Aarhus C, Denmark
| | - J Zhao
- Giome Academia, Department of Clinical Medicine, Aarhus University, Palle Juul-Jensens Blvd. 82, DK-8200 Aarhus N, Denmark
| | - D Liao
- Giome Academia, Department of Clinical Medicine, Aarhus University, Palle Juul-Jensens Blvd. 82, DK-8200 Aarhus N, Denmark
| | - L H Olsen
- Department of Clinical Medicine, Aarhus University, Palle Juul-Jensens Blvd. 82, DK-8200 Aarhus N, Denmark; Department of Urology, Section of Paediatric Urology, Aarhus University Hospital, Palle Juul-Jensens Blvd. 99, DK-8200 Aarhus N, Denmark
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El-Ayache N, Galligan JJ. 5-HT 3 receptor signaling in serotonin transporter-knockout rats: a female sex-specific animal model of visceral hypersensitivity. Am J Physiol Gastrointest Liver Physiol 2019; 316:G132-G143. [PMID: 30359082 PMCID: PMC6383387 DOI: 10.1152/ajpgi.00131.2018] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The irritable bowel syndrome (IBS) is a functional gastrointestinal motor and visceral sensation disorder that is more common in women than men. Female serotonin transporter (SERT)-gene knockout (KO) rats exhibit hypersensitivity to colorectal balloon distention (CRD) that mimics colonic hypersensitivity occurring in female IBS patients. Alosetron (5-HT3 receptor antagonist) is used to treat diarrhea-predominant IBS in female patients. Other 5-HT3 receptor antagonists are ineffective at treating IBS symptoms. The visceromotor response (VMR) to CRD in SERT-KO and wild-type (WT) rats was measured following subcutaneous (sc), intracerobroventricular (icv), or intrathecal (it) treatment with 5-HT3 receptor antagonists and an agonist. Alosetron (sc) and granisetron (antagonists) caused a paradoxical increase in the VMR to CRD in SERT-KO female rats. Alosetron (sc) increased the VMR to CRD in WT male rats. Alosetron (it) increased the VMR to CRD in SERT-KO female rats only, and the 5-HT3 receptor agonist SR-52772 increased the VMR to CRD in SERT-KO male rats. Depletion of spinal 5-HT using 5,7-dihydroxytryptamine prevented the increase in VMR to CRD in SERT-KO female and male rats treated it with alosetron and SR-52772, respectively. Alosetron (icv) did not affect the VMR to CRD in WT or KO female rats, but it increased the VMR in male SERT-KO but not WT male rats. These data suggest that 5-HT3 receptor signaling at the dorsal spinal cord mediates visceral hypersensitivity in female SERT-KO rats. Such differences could facilitate development of sex-specific drug treatments for visceral pain. NEW & NOTEWORTHY We studied a model of female sex-specific visceral hypersensitivity using rats that had a loss of function of the serotonin transporter (SERT) caused by gene truncation. Female SERT-KO rats exhibited visceral hypersensitivity in response to colorectal balloon distention. We found that increased 5-HT signaling at dorsal spine 5-HT3 receptors was responsible for visceral hypersensitivity in female but not male SERT-KO rats.
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Affiliation(s)
- Nadine El-Ayache
- 1Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan
| | - James J. Galligan
- 1Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan,2Neuroscience Program, Michigan State University, East Lansing, Michigan
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Liu Y, Zhao J, Liao D, Wang G, Gregersen H. Stress-strain analysis of duodenal contractility in response to flow and ramp distension in rabbits fed low-fiber diet. Neurogastroenterol Motil 2019; 31:e13476. [PMID: 30246440 DOI: 10.1111/nmo.13476] [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: 07/06/2018] [Revised: 08/24/2018] [Accepted: 08/28/2018] [Indexed: 12/16/2022]
Abstract
BACKGROUND Previously we demonstrated that low-fiber diet in rabbits affects the passive mechanomorphological properties in the small intestine, resulting in reduced intestinal wall thickness and collagen content, as well as intestinal wall softening. The aim of the present study was to evaluate the contractility in rabbits on long-term low-fiber diet and specifically to compare the contraction threshold, the frequency, and the amplitude of flow-induced and distension-induced contractions in the duodenum between rabbits on normal diet and on long-term low-fiber diet. METHODS Ten rabbits were fed a low-fiber diet for 5 months (Intervention group), and five rabbits were fed normal diet (Control group). The duodenal segments were used for determination of mechanical parameters for analyses of contractility. The duodenal experiments were carried out in organ baths containing physiological Krebs solution. Pressure and diameter changes induced by contractions in response to flow and ramp distension were measured. The frequencies and amplitude of contractions were analyzed. Distension-induced contraction thresholds and maximum contraction amplitude of flow-induced contractions were calculated in terms of mechanical stress and strain. Multiple linear regression analyses were applied to study dependencies between contractility parameters and wall thickness, wall area, and muscle layer thickness. KEY RESULTS During distension, the pressure, stress, and strain thresholds for induction of phasic contraction were biggest in the Intervention Group (P < 0.05). In addition, the contraction frequencies during flow-induced contraction were highest in the Intervention Group (P < 0.05), whereas the maximum contraction amplitudes in terms of pressure, diameter, stress, and strain were lowest in the Intervention Group (P < 0.05). The contraction thresholds and contraction frequencies were negatively associated with the wall thickness, wall area, and muscle layer thickness, whereas maximum contraction amplitudes were positively associated with the wall thickness, wall area, and muscle layer thickness. CONCLUSIONS AND INFERENCES Duodenal contractility in rabbits fed with long-term low-fiber diet exhibited low contraction amplitudes and high contraction thresholds and frequencies. The changes were associated with the low-fiber diet-induced histomorphological remodeling. Studies on detailed structural and functional diet-induced changes in smooth muscle and intestinal nerves are needed for better understanding the remodeling mechanisms.
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Affiliation(s)
- Yue Liu
- GIOME and the Key Laboratory for Biorheological Science and Technology of Ministry of Education, Bioengineering College of Chongqing University, Chongqing, China.,GIOME Academia, Department of Clinical Medicine, Aarhus University, Aarhus N, Denmark.,Zhuhai Da Hengqin Technology Development Co. Ltd., Zhuhai, China
| | - Jingbo Zhao
- GIOME and the Key Laboratory for Biorheological Science and Technology of Ministry of Education, Bioengineering College of Chongqing University, Chongqing, China.,GIOME Academia, Department of Clinical Medicine, Aarhus University, Aarhus N, Denmark.,Mech-Sense, Department of Gastroenterology, Aalborg University Hospital, Aalborg, Denmark
| | - Donghua Liao
- GIOME Academia, Department of Clinical Medicine, Aarhus University, Aarhus N, Denmark
| | - Guixue Wang
- GIOME and the Key Laboratory for Biorheological Science and Technology of Ministry of Education, Bioengineering College of Chongqing University, Chongqing, China
| | - Hans Gregersen
- GIOME and the Key Laboratory for Biorheological Science and Technology of Ministry of Education, Bioengineering College of Chongqing University, Chongqing, China.,GIOME, Department of Surgery, Chinese University of Hong Kong, Hong Kong SAR, China
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Kulkarni S, Ganz J, Bayrer J, Becker L, Bogunovic M, Rao M. Advances in Enteric Neurobiology: The "Brain" in the Gut in Health and Disease. J Neurosci 2018; 38:9346-9354. [PMID: 30381426 PMCID: PMC6209840 DOI: 10.1523/jneurosci.1663-18.2018] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 09/20/2018] [Accepted: 09/22/2018] [Indexed: 12/14/2022] Open
Abstract
The enteric nervous system (ENS) is a large, complex division of the peripheral nervous system that regulates many digestive, immune, hormonal, and metabolic functions. Recent advances have elucidated the dynamic nature of the mature ENS, as well as the complex, bidirectional interactions among enteric neurons, glia, and the many other cell types that are important for mediating gut behaviors. Here, we provide an overview of ENS development and maintenance, and focus on the latest insights gained from the use of novel model systems and live-imaging techniques. We discuss major advances in the understanding of enteric glia, and the functional interactions among enteric neurons, glia, and enteroendocrine cells, a large class of sensory epithelial cells. We conclude by highlighting recent work on muscularis macrophages, a group of immune cells that closely interact with the ENS in the gut wall, and the importance of neurological-immune system communication in digestive health and disease.
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Affiliation(s)
- Subhash Kulkarni
- Department of Medicine, The John Hopkins University School of Medicine, Baltimore, Maryland 21205,
| | - Julia Ganz
- Department of Integrative Biology, Michigan State University, East Lansing, Michigan 48824
| | - James Bayrer
- Department of Pediatrics, University of California, San Francisco, San Francisco, California 94143
| | - Laren Becker
- Department of Medicine, Stanford University, Stanford, California 94305
| | - Milena Bogunovic
- Department of Microbiology and Immunology, Penn State College of Medicine, Hershey, Pennsylvania 17033, and
| | - Meenakshi Rao
- Division of Gastroenterology, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts 02115
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Hoff DAL, McMahon B, Gregersen H. Esophageal multimodal stimulation and sensation. Ann N Y Acad Sci 2018; 1434:210-218. [DOI: 10.1111/nyas.13730] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Revised: 03/16/2018] [Accepted: 03/21/2018] [Indexed: 12/17/2022]
Affiliation(s)
- Dag Arne Lihaug Hoff
- Division of Gastroenterology and Hepatology, Department of Medicine, Ålesund HospitalMøre and Romsdal Hospital Trust Ålesund Norway
| | - Barry McMahon
- Trinity Academic Gastroenterology Group (TAGG)Trinity College and Tallaght Hospital Dublin Ireland
| | - Hans Gregersen
- Department of Surgerythe Chinese University of Hong Kong Shatin Hong Kong
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Gregersen H, Lo KM. What Is the Future of Impedance Planimetry in Gastroenterology? J Neurogastroenterol Motil 2018; 24:166-181. [PMID: 29605974 PMCID: PMC5885717 DOI: 10.5056/jnm18013] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Accepted: 02/09/2018] [Indexed: 12/13/2022] Open
Abstract
The gastrointestinal (GI) tract is efficient in transporting ingested material to the site of delivery in healthy subjects. A fine balance exists between peristaltic forces, the mixing and delivery of the contents, and sensory signaling. This fine balance is easily disturbed by diseases. It is mandatory to understand the pathophysiology to enhance our understanding of GI disorders. The inaccessibility and complex nervous innervation, geometry and mechanical function of the GI tract make mechanosensory evaluation difficult. Impedance planimetry is a distension technology that assesses luminal geometry, mechanical properties including muscle dynamics, and processing of nociceptive signals from the GI tract. Since standardized models do not exist for GI muscle function in vivo, models, concepts, and terminology must be borrowed from other medical fields such as cardiac mechanophysiology. The review highlights the impedance planimetric technology, muscle dynamics assessment, and 3 applied technologies of impedance planimetry. These technologies are the multimodal probes that assesses sensory function, the functional luminal imaging probe that dynamically measures the geometry of the lumen it distends, and Fecobionics that is a simulated feces providing high-resolution measurements during defecation. The advanced muscle analysis and 3 applied technologies can enhance the quality of future interdisciplinary research for gaining more knowledge about mechanical function, sensory-motor disorders, and symptoms. This is a step in the direction of individualized treatment for GI disorders based on diagnostic subtyping. There seems to be no better alternatives to impedance planimetry, but only the functional luminal imaging probe is currently commercially available. Wider use depends on commercialization of the multimodal probe and Fecobionics.
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Affiliation(s)
- Hans Gregersen
- GIOME, Department of Surgery, The Chinese University of Hong Kong, Shatin, Hong Kong.,California Medical Innovations Institute, San Diego, California, USA
| | - Kar Man Lo
- GIOME Doublecove, Wu Kai Sha, New Territories, Hong Kong
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Affiliation(s)
- Hans Gregersen
- Department of Surgery, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong
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Wang K, Ma J, Wang F, Wang Z, Yan G, Zhou Y. Full-driving soft robotic colonoscope in compliant colon tissue. J Med Eng Technol 2017; 41:662-669. [PMID: 29117761 DOI: 10.1080/03091902.2017.1394387] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Robotic colonoscopy is an efficient examination method for finding malignant tumour in its early stage. This research developed a novel robotic endoscope with 13 mm diameter, 105 mm length and 22.3 g weight. A contact biomechanical model is proposed to increase the locomotion safety and efficiency in the soft tissue. The model shows that the friction difference between the robot and the tissue is a key factor to locomotion capability. A soft, full bellow with excellent compatibility was designed to package the robot body. The bellow increased the static friction and decreased the kinetic friction given the change in the contact state. The bellow is divided into three segments. Each segment is composed of a linear locomotor with micromotor, turbine-worm and wire wrapping-sliding mechanism. The robot is tested in in vivo pig colon, which revealed an excellent locomotion capability and safety in soft tissues.
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Affiliation(s)
- Kundong Wang
- a Department of Instrument Engineering , Shanghai Jiao Tong University , Shanghai , China
| | - Jiayi Ma
- a Department of Instrument Engineering , Shanghai Jiao Tong University , Shanghai , China
| | - Feng Wang
- b Department of General Practice, School of Public Health , Shanghai University of Traditional Chinese Medicine , Shanghai , China
| | - Zhiwu Wang
- a Department of Instrument Engineering , Shanghai Jiao Tong University , Shanghai , China
| | - Guozheng Yan
- a Department of Instrument Engineering , Shanghai Jiao Tong University , Shanghai , China
| | - Yilu Zhou
- a Department of Instrument Engineering , Shanghai Jiao Tong University , Shanghai , China
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Dargar S, Akyildiz AC, De S. In Situ Mechanical Characterization of Multilayer Soft Tissue Using Ultrasound Imaging. IEEE Trans Biomed Eng 2017; 64:2595-2606. [PMID: 28026748 PMCID: PMC6218640 DOI: 10.1109/tbme.2016.2644651] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
In this paper, we report the development of a technique to characterize layer-specific nonlinear material properties of soft tissue in situ with the potential for in vivo testing. A soft tissue elastography robotic arm system comprising of a robotically manipulated 30 MHz high-resolution ultrasound probe, a custom designed compression head, and load cells has been developed to perform compression ultrasound imaging on the target tissue and measure reaction forces. A multilayer finite element model is iteratively optimized to identify the material coefficients of each layer. Validation has been performed using tissue mimicking agar-based phantoms with a low relative error of ∼7% for two-layer phantoms and ∼10% error for three layer phantoms when compared to known ground-truth values obtained using a commercial material testing system. The technique has then been used to successfully determine the in situ layer-specific mechanical properties of intact porcine stomach. The mean C10 and C20 for a second-order reduced polynomial material model were determined for the muscularis (6.41 ± 0.60, 4.29 ± 1.87 kPa), submucosal (5.21 ± 0.57, 3.68 ± 3.01 kPa), and mucosal layers (0.06 ± 0.02, 0.09 ± 0.24 kPa). Such a system can be utilized to perform in vivo mechanical characterization, which is left as future work.
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Affiliation(s)
- Saurabh Dargar
- Biomedical Engineering Department and with the Center for Modeling, Simulation and Imaging in Medicine (CeMSIM) at Rensselaer Polytechnic Institute in Troy, NY, USA.
| | - Ali C. Akyildiz
- Center for Modeling, Simulation and Imaging in Medicine (CeMSIM) at Rensselaer Polytechnic Institute in Troy, NY, USA.
| | - Suvranu De
- CeMSIM; Department of Mechanical, Aerospace and Nuclear Engineering (MANE) at Rensselaer Polytechnic Institute in Troy, NY, USA.
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Lee KJ, Vanheel H, Vanuytsel T, Vos R, Tack J. The NO/cGMP pathway in duodenal motor, mechano- and chemosensory responses to acid: A randomized, placebo-controlled study with sildenafil in healthy volunteers. Neurogastroenterol Motil 2017; 29. [PMID: 28382697 DOI: 10.1111/nmo.13076] [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: 01/04/2017] [Accepted: 03/02/2017] [Indexed: 02/08/2023]
Abstract
BACKGROUND Altered duodenal sensorimotor responses to acid have been reported in a subset of patients with functional dyspepsia. To investigate whether NO is involved in these abnormalities, the effect of sildenafil (activates the NO pathway) on duodenal motor and sensory responses to acid in healthy humans was evaluated. METHODS A barostat-manometry catheter including an infusion tube was positioned in the duodenum of 12 healthy volunteers. Duodenal motility and dyspeptic symptoms were evaluated during the whole study. A first series of stepwise isobaric distensions was performed while participants scored their perception of upper abdominal sensations at the end of every distension step. Next, the duodenum was infused with sildenafil 50 mg or saline, followed by duodenal acid infusion. During duodenal acidification, a second sequence of stepwise isobaric distensions with the assessment of sensations was repeated. KEY RESULTS Acid infusion did not induce dyspeptic symptoms with both placebo and sildenafil pretreatment. Duodenal motility decreased after sildenafil infusion, whereas it was not affected by placebo. Acid-induced increase in motility was, however, observed in both conditions, and no difference between the conditions was found. Duodenal acidification decreased thresholds for discomfort and increased perception scores during duodenal distensions in both groups, but again no difference was observed between placebo and sildenafil pretreatment. CONCLUSIONS AND INFERENCES Sildenafil does not affect duodenal motor, mechanosensory, and chemosensory responses to acid in healthy controls. Therefore, it is less likely that the NO pathway plays a role in the altered response to acid in functional dyspepsia patients.
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Affiliation(s)
- K J Lee
- Department of Gastroenterology, Ajou University School of Medicine, Suwon, Korea
| | - H Vanheel
- Translational Research Center for Gastrointestinal Disorders (TARGID), KU Leuven, Leuven, Belgium
| | - T Vanuytsel
- Translational Research Center for Gastrointestinal Disorders (TARGID), KU Leuven, Leuven, Belgium
| | - R Vos
- Translational Research Center for Gastrointestinal Disorders (TARGID), KU Leuven, Leuven, Belgium
| | - J Tack
- Translational Research Center for Gastrointestinal Disorders (TARGID), KU Leuven, Leuven, Belgium
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Peirlinck M, Debusschere N, Iannaccone F, Siersema PD, Verhegghe B, Segers P, De Beule M. An in silico biomechanical analysis of the stent–esophagus interaction. Biomech Model Mechanobiol 2017; 17:111-131. [DOI: 10.1007/s10237-017-0948-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Accepted: 08/03/2017] [Indexed: 12/15/2022]
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Haas S, Liao D, Gregersen H, Lundby L, Laurberg S, Krogh K. Increased yield pressure in the anal canal during sacral nerve stimulation: a pilot study with the functional lumen imaging probe. Neurogastroenterol Motil 2017; 29. [PMID: 27545307 DOI: 10.1111/nmo.12929] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Accepted: 07/27/2016] [Indexed: 02/08/2023]
Abstract
BACKGROUND Sacral nerve stimulation (SNS) is a well-established treatment for fecal incontinence but its mode of action remains obscure. Anal sphincter function is usually evaluated with manometry but resistance to distension may be a more appropriate parameter than luminal pressure. The functional lumen imaging probe allows detailed description of distension properties of the anal canal. Our objective in this study was to characterize the impact of SNS on distension properties of the anal canal in patients with idiopathic fecal incontinence. METHODS We studied 10 women (median age 64 [44-79] years) with idiopathic fecal incontinence at baseline and during SNS. The luminal geometry of the anal canal was examined with the FLIP at rest and during squeeze and the distensibility of the anal canal was investigated during filling of the bag. KEY RESULTS All patients were successfully treated with SNS and the mean Wexner Incontinence Score was reduced from 14.9 ± 4 to 7.1 ± 4.8 (P<.001). The pressure required to open the narrowest point of the anal canal during distension (yield pressure) increased from 14.5 ± 12.2 mmHg at baseline to 20.5 ± 13.3 mmHg during SNS (P<.01). The pressure-strain elastic modulus increased non-significantly from 2.2 ± 0.5 to 2.9 ± 1.6 kPa, indicating increased stiffness of the anal canal. CONCLUSION AND INFERENCES The yield pressure and the resistance to distension increased in response to SNS for idiopathic fecal incontinence. This will inevitably increase the resistance to flow through the anal canal, which may contribute to the benefits of sacral nerve stimulation.
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Affiliation(s)
- S Haas
- Department of Surgery P, Aarhus University Hospital, Aarhus, Denmark
| | - D Liao
- GIOME Academia, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - H Gregersen
- GIOME and the Key Laboratory for Biorheological Science and Technology of Ministry of Education, Bioengineering College of Chongqing University, Chongqing, China.,GIOME, Department of Surgery, Chinese University of Hong Kong and Prince of Whales Hospital, Shatin, Hong Kong
| | - L Lundby
- Department of Surgery P, Aarhus University Hospital, Aarhus, Denmark
| | - S Laurberg
- Department of Surgery P, Aarhus University Hospital, Aarhus, Denmark
| | - K Krogh
- Neurogastroenterology Unit, Department of Hepatology and Gastroenterology, Aarhus University Hospital, Aarhus, Denmark
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Stewart DC, Rubiano A, Santisteban MM, Shenoy V, Qi Y, Pepine CJ, Raizada MK, Simmons CS. Hypertension-linked mechanical changes of rat gut. Acta Biomater 2016; 45:296-302. [PMID: 27567964 PMCID: PMC5069177 DOI: 10.1016/j.actbio.2016.08.045] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Revised: 07/01/2016] [Accepted: 08/23/2016] [Indexed: 12/15/2022]
Abstract
Hypertension is the most prevalent risk factor for cardiovascular disease caused by a persistent increase in arterial blood pressure that has lasting effects on the mechanical properties of affected tissues like myocardium and blood vessels. Our group recently discovered that gut dysbiosis is linked to hypertension in several animal models and humans; however, whether hypertension influences the gut's mechanical properties remains unknown. In this study, we evaluated the hypothesis that hypertension increases fibrosis and thus mechanical properties of the gut. A custom indentation system was used to test colon samples from Wistar Kyoto (WKY) normotensive rats and Spontaneously Hypertensive Rats (SHR). Using force-displacement data, we derived an steady-state modulus metric to quantify mechanical properties of gastrointestinal tissue. We observed that SHR proximal colon has a mean steady-state modulus almost 3 times greater than WKY control rat colon (5.11±1.58kPa and 18.17±11.45kPa, respectively). These increases were associated with increase in vascular smooth muscle cells layer and collagen deposition in the intestinal wall in the SHR. STATEMENT OF SIGNIFICANCE Mechanical characterization of biological materials can provide insight into health and disease of tissue. Recent investigations into a variety of cardiovascular pathologies show coincident changes in the microbiome and pathology of the gut. In this study, we sought to quantify changes in the gut in hypertension through mechanical characterization. Our methods and simple models for characterization, adapted from Hertz indentation models, prove useful to identify a meaningful steady-state modulus metric for small and irregular tissues from laboratory animals. Our data, for the first time, establish a stiffening of the gut wall in Spontaneously Hypertensive Rats. This observation suggests significant structural and functional changes in the gut correlate with hypertension, and future experiments are warranted to explore the specific causal relationship between dysbiosis, fibrosis, and stiffening in the gut during the development and maintenance of hypertension.
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Affiliation(s)
- Daniel C Stewart
- J. Crayton Pruitt Family Department of Biomedical Engineering, Herbert Wertheim College of Engineering, University of Florida, Gainesville, FL, United States
| | - Andrés Rubiano
- Department of Mechanical and Aerospace Engineering, Herbert Wertheim College of Engineering, University of Florida, Gainesville, FL, United States
| | - Monica M Santisteban
- Department of Physiology and Functional Genomics, College of Medicine, University of Florida, Gainesville, FL, United States
| | - Vinayak Shenoy
- Department of Pharmacodynamics, College of Medicine, University of Florida, Gainesville, FL, United States
| | - Yanfei Qi
- Division of Cardiovascular Medicine, College of Medicine, University of Florida, Gainesville, FL, United States
| | - Carl J Pepine
- Division of Cardiovascular Medicine, College of Medicine, University of Florida, Gainesville, FL, United States
| | - Mohan K Raizada
- Department of Physiology and Functional Genomics, College of Medicine, University of Florida, Gainesville, FL, United States
| | - Chelsey S Simmons
- J. Crayton Pruitt Family Department of Biomedical Engineering, Herbert Wertheim College of Engineering, University of Florida, Gainesville, FL, United States; Department of Mechanical and Aerospace Engineering, Herbert Wertheim College of Engineering, University of Florida, Gainesville, FL, United States; Division of Cardiovascular Medicine, College of Medicine, University of Florida, Gainesville, FL, United States.
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42
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Ravages of Diabetes on Gastrointestinal Sensory-Motor Function: Implications for Pathophysiology and Treatment. Curr Gastroenterol Rep 2016; 18:6. [PMID: 26768896 DOI: 10.1007/s11894-015-0481-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Symptoms related to functional and sensory abnormalities are frequently encountered in patients with diabetes mellitus. Most symptoms are associated with impaired gastric and intestinal function. In this review, we discuss basic concepts of sensory-motor dysfunction and how they relate to clinical findings and gastrointestinal abnormalities that are commonly seen in diabetes. In addition, we review techniques that are available for investigating the autonomic nervous system, neuroimaging and neurophysiology of sensory-motor function. Such technological advances, while not readily available in the clinical setting, may facilitate stratification and individualization of therapy in diabetic patients in the future. Unraveling the structural, mechanical, and sensory remodeling in diabetes disease is based on a multidisciplinary approach that can bridge the knowledge from a variety of scientific disciplines. The final goal is to increase the understanding of the damage to GI structures and to sensory processing of symptoms, in order to assist clinicians with developing an optimal mechanics based treatment.
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43
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Brock C, Gregersen H, Gyawali CP, Lottrup C, Furnari M, Savarino E, Novais L, Frøkjaer JB, Bor S, Drewes AM. The sensory system of the esophagus--what do we know? Ann N Y Acad Sci 2016; 1380:91-103. [DOI: 10.1111/nyas.13205] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Revised: 07/19/2016] [Accepted: 07/19/2016] [Indexed: 12/13/2022]
Affiliation(s)
- Christina Brock
- Mech-Sense, Department of Gastroenterology & Hepatology, Aalborg University Hospital and Clinical Institute; Aalborg University; Aalborg Denmark
| | - Hans Gregersen
- GIOME and the Key Laboratory for Biorheological Science and Technology of Ministry of Education, College of Bioengineering; Chongqing University; Chongqing China
| | - C. Prakash Gyawali
- Division of Gastroenterology; Washington University School of Medicine; St. Louis Missouri
| | - Christian Lottrup
- Mech-Sense, Department of Gastroenterology & Hepatology, Aalborg University Hospital and Clinical Institute; Aalborg University; Aalborg Denmark
- Department of Medicine; North Jutland Regional Hospital; Hjørring Denmark
| | - Manuele Furnari
- Division of Gastroenterology, Department of Internal Medicine; University of Genoa; Genoa Italy
| | - Edoardo Savarino
- Division of Gastroenterology, Department of Surgery, Oncology and Gastroenterology; University of Padua; Padua Italy
| | - Luis Novais
- Neurogastroenterology and Gastrointestinal Motility Laboratory, Nova Medical School; Universidade Nova de Lisboa; Lisbon Portugal
| | - Jens Brøndum Frøkjaer
- Mech-Sense, Department of Radiology, Aalborg University Hospital and Clinical Institute; Aalborg University; Aalborg Denmark
| | - Serhat Bor
- Department of Gastroenterology; Ege University School of Medicine; Bornova Izmir Turkey
| | - Asbjørn Mohr Drewes
- Mech-Sense, Department of Gastroenterology & Hepatology, Aalborg University Hospital and Clinical Institute; Aalborg University; Aalborg Denmark
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44
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Farmer AD, Brock C, Frøkjaer JB, Gregersen H, Khan S, Lelic D, Lottrup C, Drewes AM. Understanding the sensory irregularities of esophageal disease. Expert Rev Gastroenterol Hepatol 2016; 10:907-14. [PMID: 26890720 DOI: 10.1586/17474124.2016.1155984] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Symptoms relating to esophageal sensory abnormalities can be encountered in the clinical environment. Such sensory abnormalities may be present in demonstrable disease, such as erosive esophagitis, and in the ostensibly normal esophagus, such as non-erosive reflux disease or functional chest pain. In this review, the authors discuss esophageal sensation and the esophageal pain system. In addition, the authors provide a primer concerning the techniques that are available for investigating the autonomic nervous system, neuroimaging and neurophysiology of esophageal sensory function. Such technological advances, whilst not readily available in the clinic may facilitate the stratification and individualization of therapy in disorders of esophageal sensation in the future.
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Affiliation(s)
- Adam D Farmer
- a Mech-Sense , University Hospital Aalborg , Aalborg , Denmark.,b Centre for Digestive Diseases, Wingate Institute of Neurogastroenterology, Blizard Institute, Barts and the London School of Medicine & Dentistry, Queen Mary University of London , London , UK.,c Department of Gastroenterology , University Hospitals of North Midlands , Stoke on Trent , UK
| | - Christina Brock
- a Mech-Sense , University Hospital Aalborg , Aalborg , Denmark
| | - Jens Brøndum Frøkjaer
- a Mech-Sense , University Hospital Aalborg , Aalborg , Denmark.,d Department of Radiology , Aalborg University Hospital , Aalborg , Denmark
| | - Hans Gregersen
- e GIOME, Key Laboratory for Biorheological Science and Technology , College of Bioengineering, Chongqing University , Chongqing , China
| | - Sheeba Khan
- c Department of Gastroenterology , University Hospitals of North Midlands , Stoke on Trent , UK
| | - Dina Lelic
- a Mech-Sense , University Hospital Aalborg , Aalborg , Denmark
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45
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Farmer AD, Franchina M, Gregersen H, Penagini R, Shaker A, Soffer E. Provocative testing of the esophagus and its future. Ann N Y Acad Sci 2016; 1380:33-47. [DOI: 10.1111/nyas.13109] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Revised: 04/21/2016] [Accepted: 04/25/2016] [Indexed: 12/25/2022]
Affiliation(s)
- Adam D. Farmer
- Centre for Digestive Diseases, Wingate Institute of Neurogastroenterology, Blizard Institute, Barts and the London School of Medicine & Dentistry; Queen Mary University of London; London United Kingdom
- Department of Gastroenterology; University Hospitals of North Midlands; Stoke on Trent Staffordshire United Kingdom
| | - Marianna Franchina
- Dipartimento di Fisiopatologia Medico-Chirurgica e dei Trapianti, Università degli Studi of Milan and Gastroenterology and Endoscopy Unit; Fondazione IRCCS Cà Granda - Ospedale Maggiore Policlinico; Milan Italy
| | - Hans Gregersen
- GIOME, College of Bioengineering; Chongqing University; Chongqing China
- Department of Surgery; Prince of Wales Hospital; Shatin Hong Kong SAR
| | - Roberto Penagini
- Dipartimento di Fisiopatologia Medico-Chirurgica e dei Trapianti, Università degli Studi of Milan and Gastroenterology and Endoscopy Unit; Fondazione IRCCS Cà Granda - Ospedale Maggiore Policlinico; Milan Italy
| | - Anisa Shaker
- Department of Medicine; University of Southern California; Los Angeles California
| | - Edy Soffer
- Department of Medicine; University of Southern California; Los Angeles California
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46
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Siegman MJ, Eto M, Butler TM. Remodeling of the rat distal colon in diabetes: function and ultrastructure. Am J Physiol Cell Physiol 2016; 310:C151-60. [PMID: 26561639 PMCID: PMC4719031 DOI: 10.1152/ajpcell.00253.2015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Accepted: 11/10/2015] [Indexed: 01/08/2023]
Abstract
This study seeks to define and explain remodeling of the distal colon in the streptozotocin (STZ)-treated rat model of diabetes through analysis of resting and active length dependence of force production, chemical composition, and ultrastructure. Compared with untreated controls, the passive stiffness on extension of the diabetic muscle is high, and active force produced at short muscle lengths is amplified but is limited by an internal resistance to shortening. The latter are accounted for by a significant increase in collagen type 1, with no changes in types 3 and 4. In the diabetic colon, ultrastructural studies show unique, conspicuous pockets of collagen among muscle cells, in addition to a thickened basement membrane and an extracellular space filled with collagen fibers and various fibrils. Measurements of DNA and total protein content revealed that the diabetic colon underwent hypertrophy, along with a proportional increase in actin and myosin contents, with no change in the actin-to-myosin ratio. Active force production per cross-sectional area was not different in the diabetic and normal muscles, consistent with the proportionality of changes in contractile proteins. The stiffness and the limit to shortening of the diabetic colon were significantly reduced by treatment with the glycation breaker alagebrium chloride (ALT-711), with no change in collagen contents. Functionally, this study shows that, in diabetes, the production of collagen type 1 and glycation increase stiffness, which limits distensibility on filling and limits shortening and expulsion of contents, both of which can be alleviated by treatment with ALT-711.
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Affiliation(s)
- Marion J Siegman
- Department of Molecular Physiology and Biophysics, Sidney Kimmel College of Medicine at Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Masumi Eto
- Department of Molecular Physiology and Biophysics, Sidney Kimmel College of Medicine at Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Thomas M Butler
- Department of Molecular Physiology and Biophysics, Sidney Kimmel College of Medicine at Thomas Jefferson University, Philadelphia, Pennsylvania
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47
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Brokjaer A, Olesen AE, Christrup LL, Dahan A, Drewes AM. The effects of morphine and methylnaltrexone on gastrointestinal pain in healthy male participants. Neurogastroenterol Motil 2015; 27:693-704. [PMID: 25810023 DOI: 10.1111/nmo.12545] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Accepted: 02/17/2015] [Indexed: 02/08/2023]
Abstract
BACKGROUND Opioid antagonists are increasingly used to abolish the gastrointestinal side effects of opioids. However, they can potentially interfere with local analgesia exerted via opioid receptors in the gut. Thus, in the current study we aimed to explore the effect of rectal morphine before and after blocking opioid receptors outside the central nervous system with methylnaltrexone (MNTX). METHODS In this randomized, placebo controlled, cross-over study 15 healthy male participants received the following drugs at three separate sessions: (i) placebo, (ii) 30 mg morphine administered per rectum, or (iii) 12 mg MNTX given subcutaneously before 30 mg rectal morphine. At baseline and after drug administration peripheral and central effects of the drugs were assessed by experimental pain to the skin, muscle, rectum and pupillometry. KEY RESULTS Compared to placebo there was no local effect of morphine on mechanical rectal distension. In contrast, an increase in tolerated volume was seen following MNTX/morphine administration (p < 0.001), starting 7 min after dosing. Both morphine and MNTX/morphine had a central effect manifested as an increase in mechanical muscle pressure thresholds (both p < 0.001) and a decrease in pupil diameter (both p < 0.001). These effects occurred 30 min after dosing. CONCLUSIONS & INFERENCES No peripheral analgesic effect of morphine was found. Methodological shortcomings may have contributed to the lack of peripheral analgesia and thus, a peripheral morphine effect on rectal pain cannot be excluded. On the other hand, the combination of MNTX and morphine exerted a local effect on rectal distensions and seems to improve analgesia.
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Affiliation(s)
- A Brokjaer
- Mech-Sense, Department of Gastroenterology & Hepatology, Aalborg University Hospital, Aalborg, Denmark
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48
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Brock C, Brokjaer A, Drewes AM, Farmer AD, Frøkjaer JB, Gregersen H, Lottrup C. Neurophysiology of the esophagus. Ann N Y Acad Sci 2015; 1325:57-68. [PMID: 25266015 DOI: 10.1111/nyas.12515] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The following, from the 12th OESO World Conference: Cancers of the Esophagus, includes commentaries on the methods and characteristics of esophageal afferents in humans; the pitfalls in characterization of mechanosensitive afferents; the sensitization of esophageal afferents in human studies; the brain source modeling in the understanding of the esophagus-brain axis; the use of evoked brain potentials in the esophagus; and measuring descending inhibition in animal and human studies.
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Affiliation(s)
- Christina Brock
- Mech-Sense, Department of Gastroenterology & Hepatology, Aalborg University Hospital, Aalborg, Denmark
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49
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Schulze KS. The imaging and modelling of the physical processes involved in digestion and absorption. Acta Physiol (Oxf) 2015; 213:394-405. [PMID: 25313872 DOI: 10.1111/apha.12407] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Revised: 06/17/2014] [Accepted: 10/07/2014] [Indexed: 01/18/2023]
Abstract
The mechanical activity of the gastro-intestinal tract serves to store, propel and digest food. Contractions disperse particles and transform solids and secretions into the two-phase slurry called chyme; movements of the intestine deliver nutrients to mucosal sites of absorption, and from the submucosa into the lymphatic and portal venous circulation. Colonic motor activity helps to extract fluid and electrolytes from chyme and to compound and compact luminal debris into faeces for elimination. We outline how dynamic imaging by ultrasound and magnetic resonance can demonstrate intestinal flow processes critical to digestion like mixing, dilution, swelling, dispersion and elution. Computational fluid mechanics enables a numerical rendition of the forces promoting digestion: pressure and flow fields, the shear stresses dispersing particles or the effectiveness of bolus mixing can be calculated. These technologies provide new insights into the mechanical processes that promote digestion and absorption.
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Affiliation(s)
- K. S. Schulze
- Department of Internal Medicine; University of Iowa; Iowa City IA USA
- VAMC; Iowa City IA USA
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50
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Jia ZG, Li W, Zhou ZR. Mechanical characterization of stomach tissue under uniaxial tensile action. J Biomech 2015; 48:651-658. [PMID: 25596630 DOI: 10.1016/j.jbiomech.2014.12.048] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Revised: 12/15/2014] [Accepted: 12/26/2014] [Indexed: 10/24/2022]
Abstract
In this article, the tensile properties of gastric wall were investigated by using biomechanical test and theoretical analysis. The samples of porcine stomach strips from smaller and greater curvature of the stomach were cut in longitudinal and circumferential direction, respectively. The loading-unloading, stress relaxation, strain creep, tensile fracture tests were performed at mucosa-submucosa, serosa-muscle and intact layer, respectively. Results showed that the biomechanical properties of the porcine stomach depended on the layers, orientations and locations of the gastric wall and presented typical viscoelastic, nonlinear and anisotropic mechanical properties. During loading-unloading test, the stress of serosa-muscle layer in the longitudinal direction was 15-20% more than that in the circumferential direction at 12% stretch ratio, while it could reach about 40% for the intact layer and 50% for the mucosa-submucosa layer. The results of stress relaxation and strain creep showed that the variation degree was obviously faster in the circumferential direction than that in the longitudinal direction, and the ultimate residual values were also different for the different layers, orientations and locations. In the process of fracture test, the serosa-muscle layer fractured firstly followed by the mucosa-submucosa layer when the intact layer was tested, the longitudinal strips firstly began to fracture and the required stress value was about twice as much as that in the circumferential strips. The anisotropy and heterogeneity of mechanical characterization of the porcine stomach were related to its complicated geometry, structure and functions. The results would help us to understand the biomechanics of soft organ tissue.
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Affiliation(s)
- Z G Jia
- Tribology Research Institute, Key Laboratory for Advanced Technology of Materials of Ministry of Education, Southwest Jiaotong University, Chengdu 610031, China
| | - W Li
- Tribology Research Institute, Key Laboratory for Advanced Technology of Materials of Ministry of Education, Southwest Jiaotong University, Chengdu 610031, China.
| | - Z R Zhou
- Tribology Research Institute, Key Laboratory for Advanced Technology of Materials of Ministry of Education, Southwest Jiaotong University, Chengdu 610031, China
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