The Effect of Digestion of Collagen and Elastin on Histomorphometry and the Zero-Stress State in Rat Esophagus

Fan, Yanhua; Zhao, Jingbo; Liao, Donghua; Gregersen, Hans

doi:10.1007/s10620-005-2868-2

Cited by 18 publications

(21 citation statements)

References 20 publications

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“…Greenwald et al (1997) showed in blood vessels that the true stress-free state can only be reached by partial destruction of the vessel wall. This is in line with our previous study showing that enzymatic digestion of elastin or collagen changes the opening angle and residual strain distribution in the rat oesophageal wall (Fan et al, 2005). Hence, the opening angle and residual strain distribution are associated with non-homogeneity in the structure and/or composition of the oesophageal wall.…”

Section: A Three-layer Modelsupporting

confidence: 92%

Opening angle and residual strain in a three-layered model of pig oesophagus

Zhao

Chen

Yang

et al. 2007

Journal of Biomechanics

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Section: A Three-layer Modelsupporting

confidence: 92%

Opening angle and residual strain in a three-layered model of pig oesophagus

Zhao

Chen

Yang

et al. 2007

Journal of Biomechanics

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“…The PEC is anatomically located in the connective tissue because the contractile element of the smooth muscle has been shown not to contribute significantly to passive tension [33]. It is more likely that the shape of the passive stress-strain curves depends on connective tissue morphology and structural components such as collagen [7,34].…”

Section: Discussionmentioning

confidence: 99%

Dimensions and Circumferential Stress-Strain Relation in the Porcine Esophagus in Vitro Determined by Combined Impedance Planimetry and High-Frequency Ultrasound

Zhao

Jørgensen²,

Liao

et al. 2007

Dig Dis Sci

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The mechanical properties of the esophagus are important for its function because the esophagus is subjected to changes in wall stress and strains caused by the passage of boli and the action of peristalsis. Electrodes for impedance planimetry and an ultrasound transducer were placed on the probe inside a fluid-filled bag and used to study the circumferential stress and strain relation of the porcine esophagus in vitro. Impedance planimetry was used to determine the luminal cross-sectional area (CSA) and high-frequency ultrasound was used to determine the esophageal wall thickness during bag distension. Circumferential stress and strain were computed from steady-state values of pressure, CSA, and wall thickness. The incremental elastic modulus was obtained from the slope of the stress-strain curve and was plotted as a function of strain. The steady state pressure-CSA relation was nonlinear. At the lowest and highest luminal pressure load of 1 and 5 kPa, the steady state CSA was 159+/-20 and 338+/-25 mm(2), respectively. In the same pressure range, the wall thickness decreased from 1.93+/-0.08 to 1.44+/-0.08 mm. The slope of the stress-strain curve was 2.58+/-0.35 kPa. The circumferential stress and the incremental elastic modulus as function of the strain were exponential, that is, the tissue was soft at physiologic pressures and stiffer in the supraphysiologic pressure range. These biomechanical properties of the esophageal wall seem to prevent overstretch of the esophageal wall when luminal loading becomes supraphysiologic.

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“…Previous zero-stress state analysis has been based on data from rat, rabbit and guinea pig [1,5,6,9,10,15] . In yet unpublished studies, the zero-stress morphology data were obtained from five male 300 g Wistar rats.…”

Section: Numerical Modelingmentioning

confidence: 99%

“…The tests were conducted in a tensile test machine consisting of an organ bath, motion table, force transducer and electronics [15,16] . The force and displacement curves were obtained simultaneously during the tensile test.…”

Section: Mechanical Propertiesmentioning

confidence: 99%

“…In yet unpublished studies, the zero-stress morphology data were obtained from five male 300 g Wistar rats. Geometric models for the oesophageal muscle and mucosal-submucosal layer were generated based on the morphology of the separated oesophagus at the zero-stress state [5,6,15] . The oesophageal passive mechanical properties were tested from the two other Wistar rats by using a tensile test machine [16,17] .…”

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confidence: 99%

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The oesophageal zero-stress state and mucosal folding from a GIOME perspective

Liao

Zhao²,

Yang³

et al. 2007

WJG

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The oesophagus is a cylindrical organ with a collapsed lumen and mucosal folds. The mucosal folding may serve to advance the function of the oesophagus, i.e. the folds have a major influence on the flow of air and bolus through the oesophagus. Experimental studies have demonstrated oesophageal mucosal folds in the noload state. This indicates that mucosal buckling must be considered in the analysis of the mechanical reference state since the material stiffness drops dramatically after tissue collapse. Most previous work on the oesophageal zero-stress state and mucosal folding has been experimental. However, numerical analysis offers a promising alternative approach, with the additional ability to predict the mucosal buckling behaviour and to calculate the regional stress and strain in complex structures. A numerical model used for describing the mechanical behaviour of the mucosal-folded, threelayered, two-dimensional oesophageal model is reviewed. GIOME models can be used in the future to predict the tissue function physiologically and pathologically. EXPERIMENTAL AND MODELING APPROACHES TO THE ZERO-STRESS STATE AND MUCOSAL BUCKLINGNew computational models for describing the gastrointestinal (GI) tract mechanical behaviour precisely are a GIOME approach for bioengineering tissue modelling. The zero-stress state provides a standardized reference state for describing the mechanical response to external loading [1][2][3][4] . A large number of studies have been published on the zero-stress state of the cardiovascular and GI systems. The zero-stress state in soft biological tissues can be obtained by an experiment where tissue rings are cut radically, opening up into sectors. The angle subtended by the open ring, referred to as the opening angle, is used as a measure of the residual stress present in the intact ring of the tissue [2] . However, recent studies on multi-layered organs such as blood vessels and the GI tract indicate that the zero-stress state differs between layers and that a stress jump exists between the layers [5][6][7][8][9][10][11] . Thus, the true stressfree configuration for a multi-layered model is at least a twice cut tissue ring; one circumferential cut for layer separation and one radial cut in each layer to generate a true stress-free state.Longitudinal mucosal folds exist throughout the length of the oesophagus. It was originally believed that the folding was caused by the contraction of the muscle layer in an in vivo state [12] . However, the folds appear even at the no-load state [5] . Hence, additional tension caused by the compressed mucosa-submucosal layer exists in the muscle layer at the no-load state. Furthermore, the mucosal layer is not perfectly elastic, its circumferential length cannot decrease to zero, thus the tension in the muscle layer will collapse the mucosal layer [12] . Therefore, the buckling feature of the oesophagus must be accounted for in a reference state analysis since the material stiffness drops dramatically after tissue collapse.In the airways it ha...

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The Effect of Digestion of Collagen and Elastin on Histomorphometry and the Zero-Stress State in Rat Esophagus

Cited by 18 publications

References 20 publications

Opening angle and residual strain in a three-layered model of pig oesophagus

Opening angle and residual strain in a three-layered model of pig oesophagus

Dimensions and Circumferential Stress-Strain Relation in the Porcine Esophagus in Vitro Determined by Combined Impedance Planimetry and High-Frequency Ultrasound

The oesophageal zero-stress state and mucosal folding from a GIOME perspective

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