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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: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [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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Nagaraja S, Leichsenring K, Ambati M, De Lorenzis L, Böl M. On a phase-field approach to model fracture of small intestine walls. Acta Biomater 2021; 130:317-331. [PMID: 34119714 DOI: 10.1016/j.actbio.2021.06.002] [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: 03/02/2021] [Revised: 05/31/2021] [Accepted: 06/02/2021] [Indexed: 12/15/2022]
Abstract
We address anisotropic elasticity and fracture in small intestine walls (SIWs) with both experimental and computational methods. Uniaxial tension experiments are performed on porcine SIW samples with varying alignments and quantify their nonlinear elastic anisotropic behavior. Fracture experiments on notched SIW strips reveal a high sensitivity of the crack propagation direction and the failure stress on the tissue orientation. From a modeling point of view, the observed anisotropic elastic response is studied with a continuum mechanical model stemming from a strain energy density with a neo-Hookean component and an anisotropic component with four families of fibers. Fracture is addressed with the phase-field approach, featuring two-fold anisotropy in the fracture toughness. Elastic and fracture model parameters are calibrated based on the experimental data, using the maximum and minimum limits of the experimental stress-stretch data set. A very good agreement between experimental data and computational results is obtained, the role of anisotropy being effectively captured by the proposed model in both the elastic and the fracture behavior. STATEMENT OF SIGNIFICANCE: This article reports a comprehensive experimental data set on the mechanical failure behavior of small intestinal tissue, and presents the corresponding protocols for preparing and testing the samples. On the one hand, the results of this study contribute to the understanding of small intestine mechanics and thus to understanding of load transfer mechanisms inside the tissue. On the other hand, these results are used as input for a phase-field modelling approach, presented in this article. The presented model can reproduce the mechanical failure behavior of the small intestine in an excellent way and is thus a promising tool for the future mechanical description of diseased small intestinal tissue.
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Feng B, Guo T. Visceral pain from colon and rectum: the mechanotransduction and biomechanics. J Neural Transm (Vienna) 2020; 127:415-429. [PMID: 31598778 PMCID: PMC7141966 DOI: 10.1007/s00702-019-02088-8] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2019] [Accepted: 09/28/2019] [Indexed: 12/14/2022]
Abstract
Visceral pain is the cardinal symptom of functional gastrointestinal (GI) disorders such as the irritable bowel syndrome (IBS) and the leading cause of patients' visit to gastroenterologists. IBS-related visceral pain usually arises from the distal colon and rectum (colorectum), an intraluminal environment that differs greatly from environment outside the body in chemical, biological, thermal, and mechanical conditions. Accordingly, visceral pain is different from cutaneous pain in several key psychophysical characteristics, which likely underlies the unsatisfactory management of visceral pain by drugs developed for other types of pain. Colorectal visceral pain is usually elicited from mechanical distension/stretch, rather than from heating, cutting, pinching, or piercing that usually evoke pain from the skin. Thus, mechanotransduction, i.e., the encoding of colorectal mechanical stimuli by sensory afferents, is crucial to the underlying mechanisms of GI-related visceral pain. This review will focus on colorectal mechanotransduction, the process of converting colorectal mechanical stimuli into trains of action potentials by the sensory afferents to inform the central nervous system (CNS). We will summarize neurophysiological studies on afferent encoding of colorectal mechanical stimuli, highlight recent advances in our understanding of colorectal biomechanics that plays critical roles in mechanotransduction, and review studies on mechano-sensitive ion channels in colorectal afferents. This review calls for focused attention on targeting colorectal mechanotransduction as a new strategy for managing visceral pain, which can also have an added benefit of limited CNS side effects, because mechanotransduction arises from peripheral organs.
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Affiliation(s)
- Bin Feng
- Department of Biomedical Engineering, University of Connecticut, 260 Glenbrook Road, Unit 3247, Storrs, CT, 06269-3247, USA.
| | - Tiantian Guo
- Department of Biomedical Engineering, University of Connecticut, 260 Glenbrook Road, Unit 3247, Storrs, CT, 06269-3247, USA
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Siri S, Maier F, Chen L, Santos S, Pierce DM, Feng B. Differential biomechanical properties of mouse distal colon and rectum innervated by the splanchnic and pelvic afferents. Am J Physiol Gastrointest Liver Physiol 2019; 316:G473-G481. [PMID: 30702901 PMCID: PMC6483024 DOI: 10.1152/ajpgi.00324.2018] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Visceral pain is one of the principal complaints of patients with irritable bowel syndrome, and this pain is reliably evoked by mechanical distension and stretch of distal colon and rectum (colorectum). This study focuses on the biomechanics of the colorectum that could play critical roles in mechanical neural encoding. We harvested the distal 30 mm of the colorectum from mice, divided evenly into three 10-mm-long segments (colonic, intermediate and rectal), and conducted biaxial mechanical stretch tests and opening-angle measurements for each tissue segment. In addition, we determined the collagen fiber orientations and contents across the thickness of the colorectal wall by nonlinear imaging via second harmonic generation (SHG). Our results reveal a progressive increase in tissue compliance and prestress from colonic to rectal segments, which supports prior electrophysiological findings of distinct mechanical neural encodings by afferents in the lumbar splanchnic nerves (LSN) and pelvic nerves (PN) that dominate colonic and rectal innervations, respectively. The colorectum is significantly more viscoelastic in the circumferential direction than in the axial direction. In addition, our SHG results reveal a rich collagen network in the submucosa and orients approximately ±30° to the axial direction, consistent with the biaxial test results presenting almost twice the stiffness in axial direction versus the circumferential direction. Results from current biomechanical study strongly indicate the prominent roles of local tissue biomechanics in determining the differential mechanical neural encoding functions in different regions of the colorectum. NEW & NOTEWORTHY Mechanical distension and stretch-not heat, cutting, or pinching-reliably evoke pain from distal colon and rectum. We report different local mechanics along the longitudinal length of the colorectum, which is consistent with the existing literature on distinct mechanotransduction of afferents innervating proximal and distal regions of the colorectum. This study draws attention to local mechanics as a potential determinant factor for mechanical neural encoding of the colorectum, which is crucial in visceral nociception.
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Affiliation(s)
- Saeed Siri
- 1Department of Biomedical Engineering, University of Connecticut, Storrs, Connecticut
| | - Franz Maier
- 2Department of Mechanical Engineering, University of Connecticut, Storrs, Connecticut
| | - Longtu Chen
- 1Department of Biomedical Engineering, University of Connecticut, Storrs, Connecticut
| | - Stephany Santos
- 2Department of Mechanical Engineering, University of Connecticut, Storrs, Connecticut
| | - David M. Pierce
- 1Department of Biomedical Engineering, University of Connecticut, Storrs, Connecticut,2Department of Mechanical Engineering, University of Connecticut, Storrs, Connecticut
| | - Bin Feng
- 1Department of Biomedical Engineering, University of Connecticut, Storrs, Connecticut
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Stein-Montalvo L, Costa P, Pezzulla M, Holmes DP. Buckling of geometrically confined shells. SOFT MATTER 2019; 15:1215-1222. [PMID: 30539965 DOI: 10.1039/c8sm02035c] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We study the periodic buckling patterns that emerge when elastic shells are subjected to geometric confinement. Residual swelling provides access to range of shapes (saddles, rolled sheets, cylinders, and spherical sections) which vary in their extrinsic and intrinsic curvatures. Our experimental and numerical data show that when these moderately thick structures are radially confined, a single geometric parameter - the ratio of the total shell radius to the amount of unconstrained material - predicts the number of lobes formed. We present a model that interprets this scaling as the competition between radial and circumferential bending. Next, we show that reducing the transverse confinement of saddles causes the lobe number to decrease with a similar scaling analysis. Hence, one geometric parameter captures the wave number through a wide range of radial and transverse confinement, connecting the shell shape to the shape of the boundary that confines it. We expect these results to be relevant for an expanse of shell shapes, and thus applicable to the design of shape-shifting materials and the swelling and growth of soft structures.
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Preparation, characterization and improvement in intestinal function of polysaccharide fractions from okra. J Funct Foods 2018. [DOI: 10.1016/j.jff.2018.09.035] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
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Thomazini BF, Dolder MAH. Effect of 60 and 90 days of isotretinoin treatment on the structure of the small intestine mucosa in young male Wistar rats. Interdiscip Toxicol 2018; 10:45-51. [PMID: 30123036 PMCID: PMC6096859 DOI: 10.1515/intox-2017-0007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Accepted: 05/16/2017] [Indexed: 11/15/2022] Open
Abstract
Isotretinoin is a substance used in cases of severe acne and acne resistant to other treatments. This skin disease affects patients of all ages and can interfere with social life, especially in adolescents. The drug acts by suppressing sebaceous gland activity and creating an inhospitable environment for Propionibacterium acne. The integrity of the small intestine is important for correct nutrition and patient treatment. We intended to assess the small intestine structure after treatment with 5 mg/kg isotretinoin solution and after a period without the drug, which could be considered a rest period. Young male Wistar rats (n=24) were separated into 4 groups (n=6): C: water; D0: soybean oil; D5a: 5 mg/kg; D5b: 5 mg/kg for 60 days followed by 30 days of rest period. Soybean oil was used to dilute the drug and it was offered daily by gavage. The animals were euthanized and the duodenum, jejunum and ileum were collected for analysis with light and scanning electron microscopy. The treatment stimulated tissue proliferation in the jejunum and ileum but had no significant effect in the duodenum. The results also showed a modification in goblet cell frequency in the duodenum and ileum. A further finding was that some modifications disappeared during the rest period. The protocol showed that the small intestine was somewhat altered by the treatment yet no lasting damage was caused.
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Affiliation(s)
- Bruna Fontana Thomazini
- Department of Structural and Functional Biology, Biology Institute, State University of Campinas, Campinas - SP, Brazil
| | - Mary Anne Heidi Dolder
- Department of Structural and Functional Biology, Biology Institute, State University of Campinas, Campinas - SP, Brazil
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Stem Cell Factor/Kit Signal Insufficiency Contributes to Hypoxia-Induced Intestinal Motility Dysfunctions in Neonatal Mice. Dig Dis Sci 2017; 62:1193-1203. [PMID: 28315973 DOI: 10.1007/s10620-017-4533-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Accepted: 03/08/2017] [Indexed: 01/25/2023]
Abstract
BACKGROUND Gastrointestinal (GI) motility disorders represent a group of problems that more constantly encountered in preterm infants. However, whether hypoxia exposure contributes to the GI dysfunctions is still unclear. METHODS Newborn mice were exposed to hypoxia (10%) from P1 to P7. Intestinal motilities were examined by a strain gauge transducer. The proliferation of ICCs was detected by using immunostaining for BrdU, Ki67, Kit, Ano1, and insulin-like growth factor 1 receptor (IGF-1R+). Smooth muscle cells and enteric neurons were revealed by immunostaining for α-SMA and NF200, respectively. Apoptosis was assessed by TUNEL assay. Kit signal pathway was examined by western blot and qPCR. RESULTS Intestinal motilities were found weakened significantly in the hypoxic small intestines as compared to controls on P8. Kit+ or Ano1+ interstitial cells of Cajal (ICCs) were found obviously decreased in the myenteric ICCs (ICC-MY) of neonatal mice after exposed to hypoxia. A large number of ICC progenitors (IGF-1R+) were found highly mitotic (BrdU+ Ki67+) to populate ICC during early postnatal development in the normoxic mice. We found the ICC proliferation was significantly inhibited upon hypoxia exposure, without increasing apoptosis (TUNEL+). We next identified that Kit phosphorylation was inhibited 3 days after hypoxia exposure. The inhibition of Kit signaling was largely due to decreased the expression of the ligand of Kit receptor, stem cell factor (SCF), in the intestinal walls. Exposure to imatinib, a Kit receptor inhibitor, for 3 days from P4 phenocopied the effect of hypoxia on the neonatal pups that resulted in inhibited intestinal motilities and decreased Kit+ ICC numbers. CONCLUSION All together, our findings indicate the SCF/Kit signaling insufficiency may contribute to the underdevelopment of ICCs and intestinal motility dysfunction upon hypoxia exposure. The decease in ICC density is likely due to the cell cycle arrest of ICC progenitor cells.
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Massalou D, Masson C, Foti P, Afquir S, Baqué P, Berdah SV, Bège T. Dynamic biomechanical characterization of colon tissue according to anatomical factors. J Biomech 2016; 49:3861-3867. [PMID: 27789033 DOI: 10.1016/j.jbiomech.2016.10.023] [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] [Received: 04/05/2016] [Revised: 10/13/2016] [Accepted: 10/16/2016] [Indexed: 10/20/2022]
Abstract
INTRODUCTION The aim of this study was to determine the mechanical response of colonic specimens retrieved from the entire human colon and placed under dynamic solicitation until the tissue ruptured. MATERIAL AND METHODS Specimens were taken from 20 refrigerated cadavers from different locations of the colonic frame (ascending, transverse, descending and sigmoid colon) in two different directions (longitudinal and circumferential), with or without muscle strips (taenia coli). A total of 120 specimens were subjected to tensile tests, after preconditioning, at the speed of 1m/s. RESULTS High-speed video analysis showed a bilayer injury process with an initial rupture of the serosa / external muscular layer followed by a second rupture of the inner layer consisting of the internal muscle / submucosa / mucosa. The mechanical response was biphasic, with a first point of initial damage followed by a complete rupture. The levels of stress and strain at the failure site were statistically greater in terms of circumferential stress (respectively 69±22% and 1.02±0.50MPa) than for longitudinal stress (respectively 55±32% and 0.70±0.34MPa). The difference between longitudinal and circumferential stress was not statistically significant (3.17±2.05MPa for longitudinal stress and 3.15±1.73MPa for circumferential stress). The location on colic frame significantly modified the mechanical response both longitudinally and circumferentially, whereas longitudinal taenia coli showed no mechanical influence. CONCLUSION The mechanical response of the colon specimen under dynamic uniaxial solicitation showed a bilayer and biphasic injury process depending on the direction of solicitation and colic localization. Furthermore these results could be integrated into a numeric model reproducing abdominal trauma to better understand and prevent intestinal injuries.
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Affiliation(s)
- D Massalou
- Emergency Surgery Unit, Universitary Hospital of Nice, Hôpital Pasteur 2, Nice Sophia-Antipolis University, France; Biomechanical Applied Laboratory, UMRT24, IFSTTAR, Aix-Marseille University, France.
| | - C Masson
- Biomechanical Applied Laboratory, UMRT24, IFSTTAR, Aix-Marseille University, France
| | - P Foti
- Emergency Surgery Unit, Universitary Hospital of Nice, Hôpital Pasteur 2, Nice Sophia-Antipolis University, France
| | - S Afquir
- Biomechanical Applied Laboratory, UMRT24, IFSTTAR, Aix-Marseille University, France
| | - P Baqué
- Emergency Surgery Unit, Universitary Hospital of Nice, Hôpital Pasteur 2, Nice Sophia-Antipolis University, France
| | - S-V Berdah
- Department of Visceral Surgery, AP-HM Hôpital Nord, Aix-Marseille University, France; Biomechanical Applied Laboratory, UMRT24, IFSTTAR, Aix-Marseille University, France
| | - T Bège
- Department of Visceral Surgery, AP-HM Hôpital Nord, Aix-Marseille University, France; Biomechanical Applied Laboratory, UMRT24, IFSTTAR, Aix-Marseille University, France
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Sjögren E, Eriksson J, Vedin C, Breitholtz K, Hilgendorf C. Excised segments of rat small intestine in Ussing chamber studies: A comparison of native and stripped tissue viability and permeability to drugs. Int J Pharm 2016; 505:361-8. [PMID: 27073083 DOI: 10.1016/j.ijpharm.2016.03.063] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Revised: 03/07/2016] [Accepted: 03/30/2016] [Indexed: 11/18/2022]
Abstract
Excised rat intestinal tissue mounted in an Ussing chamber can be used for intestinal permeability assessments in drug development. The outer layer of the intestine, the serosa and part of the muscle layer, is traditionally removed since it is considered a barrier to the diffusion of nutrients and oxygen as well as to that of pharmaceutical substances. However, the procedure for removing the serosal-muscle layer, i.e. stripping, is a technically challenging process in the pre-experimental preparation of the tissue which may result in tissue damage and reduced viability of the segment. In this study, the viability of stripped and native (non-stripped) rat small intestine tissue segments mounted in Ussing chambers was monitored and the apparent permeability of the tissue to a set of test compounds across both tissue preparations was determined. Electrical measurements, in particular the potential difference (PD) across the intestinal membrane, were used to evaluate the viability. In this study, there were no differences in initial PD (health status of the tissue) or PD over time (viability throughout the experiment) between native and stripped rat jejunum segments. Overall, there were also no significant differences in permeability between stripped and native rat intestinal tissue for the compounds in this study. Based on these results, we propose that stripping can be excluded from the preparation procedures for rat jejunal tissue for permeability studies when using the Ussing chamber technique.
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Affiliation(s)
- Erik Sjögren
- Department of Pharmacy, Uppsala University, Uppsala 75233, Sweden.
| | - Johanna Eriksson
- Department of Pharmacy, Uppsala University, Uppsala 75233, Sweden
| | - Charlotta Vedin
- DSM, Safety and ADME Translational Sciences, AstraZeneca Innovative Medicines and Early Development, Mölndal 43183, Sweden
| | - Katarina Breitholtz
- DSM, Safety and ADME Translational Sciences, AstraZeneca Innovative Medicines and Early Development, Mölndal 43183, Sweden
| | - Constanze Hilgendorf
- DSM, Safety and ADME Translational Sciences, AstraZeneca Innovative Medicines and Early Development, Mölndal 43183, Sweden
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Morphometric and biomechanical remodeling of the small intestine during aging in rats. J Biomech 2015; 48:4271-8. [DOI: 10.1016/j.jbiomech.2015.10.034] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Revised: 10/22/2015] [Accepted: 10/23/2015] [Indexed: 01/27/2023]
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Liu GF, Zhao JB, Zhen Z, Sha H, Chen PM, Li M, Zhang JC, Yuan MZ, Gao W, Gregersen H, Tong XL. Effect of Tangweian Jianji on upper gastrointestinal remodeling in streptozotocin-induced diabetic rats. World J Gastroenterol 2012; 18:4875-84. [PMID: 23002359 PMCID: PMC3447269 DOI: 10.3748/wjg.v18.i35.4875] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2012] [Revised: 04/23/2012] [Accepted: 04/27/2012] [Indexed: 02/06/2023] Open
Abstract
AIM: To investigate the effect of Tangweian Jianji (TWAJJ) on the biomechanical and morphometrical remodeling of the upper gastrointestinal tract in diabetic rats.
METHODS: Diabetes was induced in 27 rats by injecting streptozotocin (40 mg/kg body weight), the animals were then divided into three groups (n = 9 in each group), i.e., diabetic control (DM); high dose (10 g/kg, T1) and low dose (5 g/kg, T2). Another 10 rats acted as normal controls (Control). TWAJJ was administered by gavage once daily. Blood glucose and serum insulin levels were measured. Circumferential length, wall thickness and opening angle were measured from esophageal, duodenal, jejunal and ileal ring segments. The residual strain was calculated from the morphometric data. Step-wise distension was carried out on esophageal and jejunal segments. The obtained data on the length, diameter and pressure changes were then used to calculate the circumferential and longitudinal stresses and strains. Real-time reverse transcription polymerase chain reaction was used to detect the receptor of advanced glycation end-products (RAGE) mRNA level in jejunal tissues.
RESULTS: At the end of the experiment, the blood glucose level was significantly higher and the serum insulin level was significantly lower in DM, T1 and T2 groups than in the control group (Glucose: 30.23 ± 0.41 mmol/L, 27.48 ± 0.27 mmol/L and 27.84 ± 0.29 mmol/L vs 5.05 ± 0.04 mmol/L, P = 1.65 × 10-16, P = 5.89 × 10-19 and P = 1.63 × 10-18, respectively; Insulin: 1.47 ± 0.32 μg/L, 2.66 ± 0.44 μg/L, 2.03 ± 0.29 μg/L and 4.17 ± 0.54 μg/L, P = 0.0001, P = 0.029 and P = 0.025, respectively). However, these levels did not differ among the DM, T1 and T2 groups. The wet weight per unit length, wall thickness and opening angle of esophageal and intestinal segments in the DM group were significantly higher than those in the control group (from P = 0.009 to P = 0.004). These parameters in the T1 group were significantly lower than those in the DM group (wet weight, duodenum: 0.147 ± 0.003 g/cm vs 0.158 ± 0.001 g/cm, P = 0.047; jejunum, 0.127 ± 0.003 g/cm vs 0.151 ± 0.002 g/cm, P = 0.017; ileum, 0.127 ± 0.004 g/cm vs 0.139 ± 0.003 g/cm, P = 0.046; wall thickness, esophagus: 0.84 ± 0.03 mm vs 0.94 ± 0.02 mm, P = 0.014; duodenum: 1.27 ± 0.06 mm vs 1.39 ± 0.05 mm, P = 0.031; jejunum: 1.19 ± 0.07 mm vs 1.34 ± 0.04 mm, P = 0.047; ileum: 1.09 ± 0.04 mm vs 1.15 ± 0.03 mm, P = 0.049; opening angle, esophagus: 112.2 ± 13.2˚ vs 134.7 ± 14.7˚, P = 0.027; duodenum: 105.9 ± 12.3˚ vs 123.1 ± 13.1˚, P = 0.046; jejunum: 90.1 ± 15.4˚ vs 115.5 ± 13.3˚, P = 0.044; ileum: 112.9 ± 13.4˚ vs 136.1 ± 17.1˚, P = 0.035). In the esophageal and jejunal segments, the inner residual stain was significantly smaller and the outer residual strain was larger in the DM group than in the control group (P = 0.022 and P = 0.035). T1 treatment significantly restored this biomechanical alteration (P = 0.011 and P = 0.019), but T2 treatment did not. Furthermore, the circumferential and longitudinal stiffness of the esophageal and jejunal wall increased in the DM group compared with those in the control group. T1, but not T2 treatment, significantly decreased the circumferential wall stiffness in the jejunal segment (P = 0.012) and longitudinal wall stiffness in the esophageal segment (P = 0.023). The mRNA level of RAGE was significantly decreased in the T1 group compared to that in the DM group (P = 0.0069).
CONCLUSION: TWAJJ (high dose) treatment partly restored the morphometric and biomechanical remodeling of the upper gastrointestinal tract in diabetic rats.
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Gao P, Yan G, Wang Z, Jiang P, Liu H. Microgroove cushion of robotic endoscope for active locomotion in the gastrointestinal tract. Int J Med Robot 2012; 8:398-406. [DOI: 10.1002/rcs.1422] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/09/2012] [Indexed: 12/22/2022]
Affiliation(s)
- Peng Gao
- 820 Institute, Department of Instrument Science and Engineering; School of Electronic Information and Electrical Engineering, Shanghai Jiao Tong University; Shanghai; 200240; People's Republic of China
| | - Guozheng Yan
- 820 Institute, Department of Instrument Science and Engineering; School of Electronic Information and Electrical Engineering, Shanghai Jiao Tong University; Shanghai; 200240; People's Republic of China
| | - Zhiwu Wang
- 820 Institute, Department of Instrument Science and Engineering; School of Electronic Information and Electrical Engineering, Shanghai Jiao Tong University; Shanghai; 200240; People's Republic of China
| | - Pingping Jiang
- 820 Institute, Department of Instrument Science and Engineering; School of Electronic Information and Electrical Engineering, Shanghai Jiao Tong University; Shanghai; 200240; People's Republic of China
| | - Hua Liu
- 820 Institute, Department of Instrument Science and Engineering; School of Electronic Information and Electrical Engineering, Shanghai Jiao Tong University; Shanghai; 200240; People's Republic of China
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Evaluation of residual stresses due to bone callus growth: A computational study. J Biomech 2011; 44:1782-7. [DOI: 10.1016/j.jbiomech.2011.04.021] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2010] [Revised: 03/18/2011] [Accepted: 04/14/2011] [Indexed: 11/18/2022]
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Moulton DE, Goriely A. Possible role of differential growth in airway wall remodeling in asthma. J Appl Physiol (1985) 2011; 110:1003-12. [PMID: 21252217 DOI: 10.1152/japplphysiol.00991.2010] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Airway remodeling in patients with chronic asthma is characterized by a thickening of the airway walls. It has been demonstrated in previous theoretical models that this change in thickness can have an important mechanical effect on the properties of the wall, in particular on the phenomenon of mucosal folding induced by smooth muscle contraction. In this paper, we present a model for mucosal folding of the airway in the context of growth. The airway is modeled as a bilayered cylindrical tube, with both geometric and material nonlinearities accounted for via the theory of finite elasticity. Growth is incorporated into the model through the theory of morphoelasticity. We explore a range of growth possibilities, allowing for anisotropic growth as well as different growth rates in each layer. Such nonuniform growth, referred to as differential growth, can change the properties of the material beyond geometrical changes through the generation of residual stresses. We demonstrate that differential growth can have a dramatic impact on mucosal folding, in particular on the critical pressure needed to induce folding, the buckling pattern, as well as airway narrowing. We conclude that growth may be an important component in airway remodeling.
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Affiliation(s)
- D E Moulton
- OCCAM, Institute of Mathematics, Univ. of Oxford, Oxford, UK.
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16
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Zhao J, Liao D, Yang J, Gregersen H. Biomechanical remodelling of obstructed guinea pig jejunum. J Biomech 2010; 43:1322-9. [PMID: 20189575 PMCID: PMC2857539 DOI: 10.1016/j.jbiomech.2010.01.018] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2009] [Revised: 12/18/2009] [Accepted: 01/21/2010] [Indexed: 01/19/2023]
Abstract
Data on morphological and biomechanical remodelling are needed to understand the mechanisms behind intestinal obstruction. The effect of partial obstruction on mechanical properties with reference to the zero-stress state and on the histomorphological properties of the guinea pig small intestine was determined in this study. Partial obstruction and sham operation were surgically created in mid-jejunum of guinea pigs. The animals survived 2, 4, 7, and 14 days. The age-matched guinea pigs that were not operated served as normal controls. The segment proximal to the obstruction site was used for histological analysis, no-load state and zero-stress state data, and distension test. The segment for distension was immersed in an organ bath and inflated to 10cm H(2)O. The outer diameter change during the inflation was monitored using a microscope with CCD camera. Circumferential stresses and strains were computed from the diameter, pressure and the zero-stress state data. The opening angle and absolute value of residual strain decreased (P<0.01 and P<0.001) whereas the wall thickness, wall cross-sectional area, and the wall stiffness increased after 7 days obstruction (P<0.05, P<0.01). Histologically, the muscle and submucosa layers, especially the circumferential muscle layer increased in thickness after obstruction. The opening angle and residual strain mainly depended on the thickness of the muscle layer whereas the wall stiffness mainly depended on the thickness of the submucosa layer. In conclusion, the histomorphological and biomechanical properties of small intestine (referenced for the first time to the zero-stress state) remodel proximal to the obstruction site in a time-dependent manner.
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Affiliation(s)
- Jingbo Zhao
- Mech-Sense, Aalborg Hospital Science and Innovation Centre (AHSIC), Sdr. Skovvej 15, DK-9000 Aalborg, Denmark.
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Han J, Shen WH, Jiang YZ, Yu B, He YT, Li N, Mei F. Distribution, development and proliferation of interstitial cells of Cajal in murine colon: an immunohistochemical study from neonatal to adult life. Histochem Cell Biol 2009; 133:163-75. [PMID: 19894060 DOI: 10.1007/s00418-009-0655-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/14/2009] [Indexed: 11/29/2022]
Abstract
This paper aimed at investigating the alterations in interstitial cells of Cajal (ICC) in the proximal, middle and distal colon of mice from 0-day to 56-day post-partum (P0-P56) by immunohistochemistry. The Kit(+) ICC, which situated around myenteric nerve plexus (ICC-MY) were prominent at birth, meanwhile those cells within the smooth muscle layers (ICC-IM) and in the connective tissue beneath serosa (ICC-SS) began to appear. ICC-SM, which located at the submucosal border of circular muscle layer emerged at P6 in the proximal colon and subsequently in the distal colon at P8, and ICC in the oral side of colon revealed an earlier development in morphology and a higher density than that in the anal side. The density of ICC altered obviously during postnatal period, and the estimated total amount of ICC increased approximately 30 folds at P56 than that at P0. Some Kit(+)/Ki67(+) and Kit(+)/BrdU(+) cells were observed in ICC-MY, ICC-IM and ICC-SS, but not in ICC-SM from P0 to P24. Our result indicates a proximal to distal and transmural gradient development of ICC in the postnatal colon along with a dramatic increase of ICC cell number from neonatal to adult life, and an age-dependent proliferation of ICC is also involved.
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Affiliation(s)
- Juan Han
- Department of Histology and Embryology, Third Military Medical University, Chongqing, China
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18
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Ciarletta P, Dario P, Tendick F, Micera S. Hyperelastic Model of Anisotropic Fiber Reinforcements within Intestinal Walls for Applications in Medical Robotics. Int J Rob Res 2009. [DOI: 10.1177/0278364909101190] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The development of an anatomically realistic model of intestinal tissue is essential for the progress of several clinical applications of medical robotics. A hyperelastic theory of the layered structure of the intestine is proposed in this paper to reproduce its purely elastic passive response from the structural organization of its main constituents. The hyperelastic strain energy function is decoupled into an isotropic term, describing the ground biological matrix, and an anisotropic term, describing the single contributions of the directional fiber-reinforcements. The response of the muscular coat layer has been modeled as a stiffening effect due to two longitudinal and circular muscular reinforcements. The contribution of the submucosa has been described from a uniform distribution of fibrillar collagen in a cross-ply arrangement. An experimental procedure has been proposed in order to characterize the passive response of porcine intestinal samples from planar uniaxial traction and shear tests. The experimental data have been non-linearly fitted in the least square sense with the results of the theoretical predictions. The mechanical parameters have been fitted with high accuracy (Rmin =0.9329, RMSEmax =0.01167), demonstrating the ability of the model to reproduce the mechanical coupling due to the presence of multiple directional reinforcements. The fundamental mechanical role of collagen morphology in the passive biomechanical behavior of intestinal wall is demonstrated. These results may drive a better understanding of the key factors in growth and remodeling of healthy and diseased tissue, together with numerous applications in robotic endoscopy, minimally invasive surgery, and biomedical research.
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Affiliation(s)
- P. Ciarletta
- CRIM Laboratory, Scuola Superiore Sant'Anna, Viae Rinaldo Piaggio 34, Pontedera (Pisa), Italy,
| | - P. Dario
- CRIM Laboratory, Scuola Superiore Sant'Anna, Viae Rinaldo Piaggio 34, Pontedera (Pisa), Italy,
| | - F. Tendick
- Department of Surgery, University of California, San Francisco, CA, USA,
| | - S. Micera
- ARTS Laboratory, Scuola Superiore Sant'Anna, Viae Rinaldo Piaggio 34, Pontedera (Pisa), Italy,
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Yang J, Zhao J, Nakaguchi T, Gregersen H. Biomechanical changes in oxazolone-induced colitis in BALB/C mice. J Biomech 2009; 42:811-7. [PMID: 19264309 DOI: 10.1016/j.jbiomech.2009.01.028] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2008] [Revised: 01/28/2009] [Accepted: 01/28/2009] [Indexed: 01/08/2023]
Abstract
Ulcerative colitis (UC) is associated with intestinal and extra intestinal clinical manifestations. The profound organic changes in UC indicate that the colonic mechanical and mechanosensory functions are affected. The aim was to study acute morphological and biomechanical properties of the distal colon in oxazolone-induced UC in BALB/C mice. Six normal male BALB/C mice and 10 oxazolone-induced UC mice were studied. UC was induced by epicutaneous and intrarectal administration of oxazolone. The mechanical test was done as a distension experiment where the colon was distended up to 20 cmH2O. The pressure, outer diameter and length were recorded simultaneously. Circumferential and longitudinal stresses and strains were computed. The intestinal specimens were processed for histology. The mucosa was infiltrated with acute and chronic inflammatory cells. Mucosal bleeding, irregular ulcers crypt abscess, and destruction of the epithelial border were observed. Although, the mucosa in ulcers was much thinner than in the normal controls, the mucosa and submucosa around the ulcer were thicker than in the normal controls (P<0.05). Oxazolone-induced colitis increased the circumferences and wall cross-sectional area (P<0.01), the opening angle and residual strain at the serosa increased (P<0.01). Furthermore, the circumferential and longitudinal stiffness increased in the UC wall and was most pronounced in longitudinal direction. The opening angle and residual strain was linearly correlated to the wall thickness, area and inflammation degree. In conclusion, morphological and biomechanical changes of the colon occurred during the development of UC. The increased stiffness may contribute to the abnormal function in patients with UC.
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Affiliation(s)
- Jian Yang
- Mech-Sense, Aalborg Hospital Science and Innovation Centre (AHSIC), Aalborg Hospital, Sdr. Skovvej 15, DK 9000 Aalborg, Denmark
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Abstract
The gastrointestinal (GI) tract is the system of organs within multi-cellular animals that takes in food, digests it to extract energy and nutrients, and expels the remaining waste. The various patterns of GI tract function are generated by the integrated behaviour of multiple tissues and cell types. A thorough study of the GI tract requires understanding of the interactions between cells, tissues and gastrointestinal organs in health and disease. This depends on knowledge, not only of numerous cellular ionic current mechanisms and signal transduction pathways, but also of large scale GI tissue structures and the special distribution of the nervous network. A unique way of coping with this explosion in complexity is mathematical and computational modelling; providing a computational framework for the multilevel modelling and simulation of the human gastrointestinal anatomy and physiology. The aim of this review is to describe the current status of biomechanical modelling work of the GI tract in humans and animals, which can be further used to integrate the physiological, anatomical and medical knowledge of the GI system. Such modelling will aid research and ensure that medical professionals benefit, through the provision of relevant and precise information about the patient’s condition and GI remodelling in animal disease models. It will also improve the accuracy and efficiency of medical procedures, which could result in reduced cost for diagnosis and treatment.
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Mei F, Zhu J, Guo S, Zhou DS, Han J, Yu B, Li SF, Jiang ZY, Xiong CJ. An age-dependent proliferation is involved in the postnatal development of interstitial cells of Cajal in the small intestine of mice. Histochem Cell Biol 2008; 131:43-53. [PMID: 18836738 DOI: 10.1007/s00418-008-0515-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/13/2008] [Indexed: 12/28/2022]
Abstract
This paper aimed at investigating the alterations in interstitial cells of Cajal (ICCs) in the murine small intestine from 0-day to 56-day post-partum (P0-P56) by immunohistochemistry. The Kit+ ICCs, which were situated around myenteric nerve plexus (ICC-MY) formed a loose cellular network at P0 which changed into an intact one before P32. The density of ICC-MY increased from P0 to P12, and then decreased until P32. In contrast, the estimated total amount increased more than 15-fold at P32 than that at P0. Some Kit+/BrdU+ cells were observed at 24 h after one BrdU injection to the different-aged mice, and the number decreased from P2 to P24 and vanished at P32. Actually a few Kit+/BrdU+ cells can be observed at 1 h after one BrdU injection at P10, and the amount doubled at 24 h along with paired Kit+/BrdU+ cells. A number of BrdU+ ICCs were also labeled with CD34, CD44 and insulin-like growth factor I receptor. About 65% ICCs were BrdU+ at P32 after daily BrdU injection from P0. Our results indicate that an age-dependent proliferation is involved in the postnatal development of ICC-MY which increase greatly in cell numbers and proliferative ICCs may originate from ICCs progenitor cells.
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Affiliation(s)
- Feng Mei
- Department of Histology and Embryology, Third Military Medical University, 400038, Chongqing, China.
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Liao D, Lelic D, Gao F, Drewes AM, Gregersen H. Biomechanical functional and sensory modelling of the gastrointestinal tract. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2008; 366:3281-3299. [PMID: 18593660 DOI: 10.1098/rsta.2008.0091] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The aim of this review is to describe the biomechanical, functional and sensory modelling work that can be used to integrate the physiological, anatomical and medical knowledge of the gastrointestinal (GI) system. The computational modelling in the GI tract was designed, implemented and evaluated using a series of information and communication technologies-based tools. These tools modelled the morphometry, biomechanics, functions and sensory aspects of the human GI tract. The research presented in this review is based on the virtual physiological human concept that pursues a holistic approach to representation of the human body. Such computational modelling combines imaging data, GI physiology, the gut-brain axis, geometrical and biomechanical reconstruction, and computer graphics for mechanical, electronic and pain analysis. The developed modelling will aid research and ensure that medical professionals benefit through the provision of relevant and precise information about a patient's condition. It will also improve the accuracy and efficiency of the medical procedures that could result in reduced cost for diagnosis and treatment.
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Affiliation(s)
- Donghua Liao
- Mech-Sense, Aalborg Hospital Science and Innovation Centre, Søndre Skovvej 15, 9000 Aalborg, Denmark.
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Effect of smooth muscle tone on morphometry and residual strain in rat duodenum, jejunum and ileum. J Biomech 2008; 41:2667-72. [DOI: 10.1016/j.jbiomech.2008.06.017] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2008] [Revised: 06/05/2008] [Accepted: 06/10/2008] [Indexed: 11/22/2022]
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Storkholm JH, Zhao J, Villadsen GE, Hager H, Jensen SL, Gregersen H. Biomechanical remodeling of the chronically obstructed Guinea pig small intestine. Dig Dis Sci 2007; 52:336-46. [PMID: 17219069 DOI: 10.1007/s10620-006-9431-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2006] [Accepted: 05/05/2006] [Indexed: 01/29/2023]
Abstract
Small intestinal obstruction is a frequently encountered clinical problem. To understand the mechanisms behind obstruction and the clinical consequences, data are needed on the relation between the morphologic and biomechanical remodeling that takes place in the intestinal wall during chronic obstruction. We sought to determine the effect of partial obstruction on mechanical and morphologic properties of the guinea pig small intestine. Partial obstruction was created surgically in 2 groups of animals living for 2 and 4 weeks. Controls were sham operated and lived for 4 weeks. A combined impedance planimetry-high-frequency ultrasound system was designed to measure the luminal cross-sectional area and wall thickness. These measures were used to compute the circumferential stress and strain of the excised intestinal segments. The incremental elastic modulus was obtained by using nonlinear fitting of the stress-strain curve. Histologic analysis and the measurements of total wall collagen were also performed. The luminal cross-sectional area, wall thickness, and elastic modulus in circumferential direction increased in a time-dependent manner proximal to the obstruction site (P < 0.01), whereas no differences in these parameters were found distal to the obstruction site (P > 0.25). The circumferential stress-strain curves of the proximal segments in 2- and 4-week groups shifted to the left, indicating the intestinal wall became stiffer. Histologic examination revealed a massive increase in the thickness of the muscle layer especially the circular smooth muscle layer (P < 0.05). The collagen content proximal to the obstruction site was significantly larger in the partially obstructed animals compared to controls (P < 0.05). No difference was found distal to the obstruction site. Strong correlation was found between the collagen content and the elastic modulus at stress levels of 70 kPa stress (P < 0.01) and 10 kPa (P < 0.05) proximal to the obstruction site suggesting that the alteration of collagen has great impact on the mechanical remodeling. The morphologic and biomechanical remodeling likely influence the function of the intestine affected by partial obstructed intestine.
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MESH Headings
- Animals
- Biomechanical Phenomena
- Chronic Disease
- Collagen/metabolism
- Disease Models, Animal
- Elasticity
- Electric Impedance
- Gastrointestinal Motility
- Guinea Pigs
- Intestinal Obstruction/metabolism
- Intestinal Obstruction/pathology
- Intestinal Obstruction/physiopathology
- Intestine, Small/metabolism
- Intestine, Small/pathology
- Intestine, Small/physiopathology
- Intestine, Small/surgery
- Male
- Models, Biological
- Muscle, Smooth/metabolism
- Muscle, Smooth/pathology
- Muscle, Smooth/physiopathology
- Muscle, Smooth/surgery
- Nonlinear Dynamics
- Peristalsis
- Pressure
- Random Allocation
- Stress, Mechanical
- Tensile Strength
- Time Factors
- Ultrasonics
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Zhao J, Chen X, Yang J, Liao D, Gregersen H. Opening angle and residual strain in a three-layered model of pig oesophagus. J Biomech 2007; 40:3187-92. [PMID: 17517416 DOI: 10.1016/j.jbiomech.2007.04.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2007] [Revised: 04/02/2007] [Accepted: 04/02/2007] [Indexed: 01/19/2023]
Abstract
Studies of various biological tissues have shown that residual strains are important for tissue function. Since a force balance exists in whole wall thickness specimens cut radially, it is evident that layer separation is an important procedure in the understanding of the meaning of residual stresses and strains. The present study investigated the zero-stress state and residual strain distribution in a three-layer model of the pig oesophagus. The middle part of the oesophagus was obtained from six slaughterhouse pigs. Four 3-mm-wide rings were serially cut from each oesophagus. Two of them were used for separating the wall into mucosa-submucosa, inner and outer muscle layers. The remaining two rings were kept as intact rings. The inner and outer circumferences and wall thickness of different layers in intact and separated rings were measured from the digital images in the no-load state and zero-stress state. The opening angle was measured and the residual strain at the inner and outer surface of different layers and the intact wall were computed. Compared with intact sectors (62.8+/-9.8 degrees ), the opening angles were smaller in the inner muscle sectors (37.2+/-11.4 degrees , P<0.01), whereas the opening angles of mucosa-submucosa (63.9+/-6.8 degrees ) and outer muscle sectors (63.9+/-6.8 degrees ) did not differ (P>0.1). Referenced to the zero-stress state of the intact sectors, the inner and outer residual strains of the intact rings was -0.128+/-0.043 and outer residual strain was 0.308+/-0.032. Referenced to the "true" zero-stress state of separated three-layered sectors, the inner residual strain of intact rings were -0.223+/-0.021 (P<0.01) and 0.071+/-0.022 (P<0.01). Referenced to the "true" zero-stress state, the residual strain distribution of different layers in intact rings was shown that the inner surface residual strain was negative at mucosa-submucosa and inner muscle layers and was positive at outer muscle layer, whereas the outer surface residual strain was negative at the mucosa-submucosa layer and positive at the inner and outer muscle layers. For the separated different layered rings, the inner residual strain was negative and outer residual strain was positive; however, the absolute values did not differ (P>0.1). In conclusion, it is possible to microsurgically separate the oesophagus into three layers, i.e., mucosa-submucosa, inner muscle and outer muscle layers, the residual strain differ between the layers, and the residual strain distribution was more uniform after the layers were separated.
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Affiliation(s)
- Jingbo Zhao
- Center of Excellence in Visceral Biomechanics and Pain, Aalborg Hospital Science and Innovation Center, Room 404, Aalborg Hospital, Søndre Skovvej 15, DK 9000 Aalborg, Denmark.
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Ekmektzoglou KA, Zografos GC, Kourkoulis SK, Dontas IA, Giannopoulos PK, Marinou KA, Poulakou MV, Perrea DN. Mechanical behavior of colonic anastomosis in experimental settings as a measure of wound repair and tissue integrity. World J Gastroenterol 2006; 12:5668-73. [PMID: 17007020 PMCID: PMC4088168 DOI: 10.3748/wjg.v12.i35.5668] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To determine the mechanical properties of anastomotic colonic tissue in experimental settings and therefore give a measure of wound healing.
METHODS: Thirty-six male Wistar rats were used as experimental models of anastomotic tissue integrity. On the 5th post-operative day, the tensile strength was measured by application of an axial force, providing a quantitative measure of anastomotic dehiscence and leakage.
RESULTS: Diagrams of the load as a function of the time [P = P (t)] and of the displacement also as a function of time [Δs = Δs (t)] were recorded for each test, permitting the design of the load versus the displacement diagram and thus providing significant data about the critical values of anastomotic failure. Quantitative data were obtained concerning the anastomotic strength of both control specimens (healthy rats), as well as specimens from non-healthy rats for comparison.
CONCLUSION: This experimental model provides an excellent method of measuring anastomotic strength. Despite the relative small number of specimens used, this method provides an accurate way of measuring wound repair. More experimental measurements need to be performed to correlate emerging tensile strength values to anastomotic failure.
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Affiliation(s)
- Konstantinos A Ekmektzoglou
- Laboratory of Experimental Surgery and Surgical Research "NS Christeas", University of Athens, Medical School, Greece, Melissia, Athens 15127, Greece.
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