Dynamics of intestinal propulsion

Miftahof, Roustem N.; Akhmadeev, Nariman

doi:10.1016/j.jtbi.2007.01.006

Cited by 33 publications

(16 citation statements)

References 15 publications

(14 reference statements)

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“…Longitudinal stretch decreased the circumferential muscle contractility. Such information may be relevant because lengthening can be caused by shear stresses induced by chyme flow [10,23], longitudinal muscle relaxation [24], and distension due to obstructive diseases [25,26]. The 20% elongation used in this study is probably in the same range as such physiological length changes whereas the deformation used in muscle strips studies often are much larger.…”

Section: Active-passive Stress-strain Curves and Longitudinal Stretchmentioning

confidence: 96%

Phasic and Tonic Stress–Strain Data Obtained in Intact Intestinal Segment In Vitro

2008

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The function of the small intestine is to a large degree mechanical, and it has the capability of deforming its shape by generating phasic (short-lasting) and tonic (sustained) contraction of the smooth muscle layers. The aim of this study was to obtain phasic and tonic stress-strain (normalized force-length) curves during distension of isolated rat jejunum and ileum (somewhat similar to the isometric length-tension diagram known from in vitro studies of muscle strips). We hypothesized that the circumferential stress-strain data depend on longitudinal stretch of the intestine. Intestinal segments were isolated from ten Wistar rats and put into an organ bath containing 37 degrees C aerated Krebs solution. Ramp distension was done on active and passive intestinal segments at longitudinal stretch ratios of 0, 10, and 20%. Ramp pressures from 0 to 7.5 cmH(2)O were applied to the intestinal lumen at each longitudinal stretch ratio. Passive conditions were obtained by adding the calcium antagonist papaverine to the solution. Total and passive circumferential stress and strain were computed from the length, diameter and pressure data and from the zero-stress state geometry. The active stress was defined as the total stress minus the passive stress. The total and passive circumferential stresses increased exponentially as a function of the strain. The amplitude of both the total and passive stress was biggest in the jejunum. The total circumferential stress decreased whereas the passive circumferential stress increased when the intestine was stretched longitudinally. Consequently, longitudinal stretching caused the active circumferential stress to decrease. The passive circumferential stress during longitudinal stretching increased more in the jejunum than in the ileum. Therefore, the active circumferential stress decreased most in the jejunum. In conclusion, the circumferential active-passive stress and strain depend on the longitudinal stretch and differs between the jejunum and ileum.

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Section: Active-passive Stress-strain Curves and Longitudinal Stretchmentioning

confidence: 96%

Phasic and Tonic Stress–Strain Data Obtained in Intact Intestinal Segment In Vitro

2008

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“…The TAMs were then connected to the grip of a tensile test machine (BOSE Electroforce 3200 instrument, BOSE Inc.). The tensile test system was used to apply sinusoidal pull force, which has a peak value 0.4 N and lasts 6 s for each cycle (close to the maximum human intestine traction force (Miftahof and Akhmadeev 2007) and peristalsis frequency (Froehlich et al 2005)). The TAMs were immersed into saline during the entire test, and the volumes of the mechanism were calculated to make sure the buoyancy force offsets the weight of the TAM.…”

Section: In Vitro Adhesion Damage Testmentioning

confidence: 99%

A bio-inspired attachment mechanism for long-term adhesion to the small intestine

Xie

Kothari

Terry

2015

Biomed Microdevices

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To achieve long-term attachment of capsule endoscopes (CEs) and miniature biosensors in the human gastrointestinal (GI) tract, a tissue attachment mechanism (TAM) was designed, optimized and tested for safety and adhesive capabilities on excised tissue in vitro and in vivo on a live pig model. Six TAMs were tested for their attachment strength in an in vitro attachment tensile experiment in which each TAM was tested on three different proximal intestine tissue samples. The maximum strength and average value are 8.09 N and 4.54 N respectively. The initial attachment damage was tested for 10 min using a sine wave pull force on the TAM with a 0.4 N peak value and 6 s period, which represents typical human intestinal traction force from peristalsis. The in vitro attachment tensile test verified that the tissue was not visually damaged nor perforated by the attachment process. In the in vivo experiment, four TAMs were placed in the intestine of a pig through individual longitudinal enterotomies. X-ray images were taken each hour after the surgery and showed zero migration of the TAMs after 24 h of adhesion. X-ray images taken each day indicated the attachment duration of this mechanism lasted up to 6 days. Post experiment inspection confirmed the attachment did not cause visible damage to tissue. These results confirmed the reliability of the TAM in vivo and demonstrated preliminary feasibility of long-term sensor adhesion to the GI tract.

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“…The majority of pharmacokinetic studies focus on a compartmentalised approach; a paper by Stoll et al (2000) applies the Smoluchowski equation (an advection-diffusion equation) to the movement of drugs in the small intestine, including a reaction term to account for absorption of the drug. Miftahof and Akhmadeev (2007) presented a biomechanical gut segment and mathematically modelled its propulsion as a solid and non-deformable pellet using finite difference and finite element methods. residence times, solubility) and does not provide an understanding of the nature of the flow and mixing, which might have a profound effect.…”

Section: Modelling Small Intestine Processesmentioning

confidence: 99%