Peristaltic transport of a heat-conducting fluid subject to Newton's cooling law at the boundary
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Keywords:
Peristalsis
Peristalsis
Peristaltic pump
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It has earlier been demonstrated after long-term monitoring of pH and peristalsis in the oesophagus that episodes of acid gastro-oesophageal reflux occur in normal volunteers. to determine whether there is a connection between gastro-oesophageal reflux and prior peristalsis, pH and peristalsis were monitored for 12 h in 26 asymptomatic subjects. The recorded peristalsis was divided into brief bursts of peristaltic contractions (≤60sec) and more prolonged continuous activity. Peristaltic periods were limited to prior and subsequent peristalsis by a non-peristaltic course of ≥ 30 sec. Continuous peristalsis was defined as a sequence of peristaltic contractions with a mutual distance between individual peristaltic waves of ≤ 30 sec. A total of 81 episodes of reflux were recorded, of which 67 were preceded by peristaltic activity. Brief bursts of peristalsis, unrelated to reflux episodes, were frequently terminated by boslus-transporting peristaltic waves (p < 0.001). When the last contraction before reflux was considered, an increased frequency of non-propagating peristalsis was found (p < 0.01). In addition, a closer time relationship was observed between peristalsis and reflux if the last contraction was of the upper segmentary type, as compared with propagating activity (p < 0.001). In conclusion, reflectory sphincter relaxation producing reflux may possibly be triggered by contractions in the upper part of the oseophagus, not followed by a bolus-transporting peristaltic wave.
Peristalsis
Peristaltic pump
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Peristalsis
Peristaltic pump
Tetrodotoxin
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The study evaluates the triggering and characteristics of secondary oesophageal peristalsis in 25 healthy volunteers. Secondary peristalsis was stimulated by rapid intraoesophageal injection of boluses of air and water, and by a five second oesophageal distension with a balloon. Air and water boluses triggered secondary peristalsis that started in the proximal oesophagus regardless of injection site. Response rates were volume dependent with 83% of the 20 ml air boluses triggering secondary peristalsis compared with 2% for the 2 ml water bolus (p < 0.0001). Response rates for air and water were similar for equal bolus volumes and were not influenced by the site of injection. In contrast, balloon distension usually induced a synchronous contraction above the balloon, with secondary peristalsis starting below the balloon after deflation. The peristaltic response rate to balloon distension was also volume dependent and the middle balloon was more effective in triggering secondary peristalsis than either the upper or lower balloons (p < 0.001). Secondary peristaltic amplitude was less than that of primary peristalsis (p < 0.001). Secondary peristaltic velocity with a water bolus was slower (p = 0.001) than that of primary peristalsis. Intravenous atropine significantly reduced secondary peristaltic responses to all stimuli. There was also a significant reduction in pressure wave amplitude for air stimulated secondary peristalsis while those for the water responses were similar. Secondary peristaltic velocity with air and water boluses was not changed by atropine. The reproducibility of testing secondary peristalsis was examined six volunteers and did not show any significant differences on separate test days in response rate and peristaltic amplitude or velocity. It is concluded that in normal subjects, secondary peristalsis can be more reliably triggered by intraoesophageal air or water infusion than balloon distension. Secondary peristaltic amplitude and velocity are stimulus but not site or volume dependent and propagation is partially mediated by cholinergic nerves.
Peristalsis
Bolus (digestion)
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Peristalsis is the aboral movement by which the intestine propels its contents. Since pharmacological research requires an experimental model with which drug-induced modifications of peristalsis can be reliably quantified, we set out to develop and validate an in vitro method for studying peristalsis in multiple gut segments. In our arrangement, up to four 10cm segments isolated from the guinea-pig jejunum and ileum can be set up in parallel and their lumens perfused. Peristalsis was elicited by pressure-evoked wall distension, and the peristalsis-induced changes in the intraluminal pressure were evaluated with software that determined the peristaltic pressure threshold, the frequency, maximal acceleration and amplitude of the peristaltic waves, and the residual baseline pressure. Validation experiments showed that the peristalsis parameters at baseline and after modification by morphine (0.01–10μM) did not differ between segments from the jejunum and ileum, or between segments examined in a consecutive manner. In conclusion, our work succeeded in optimising the use of the guinea-pig jejunum and ileum for multiple recordings of peristalsis in vitro, and in refining the recording and evaluation of peristaltic motility. This system promises to be particularly useful in the pharmacological screening and testing of drugs which modify peristalsis.
Peristalsis
New guinea
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Ureteral peristalsis in five pregnant patients with signs of acute renal outflow obstruction was studied with the aid of a new technique for recording intraureteral pressure (ureterometry). With this technique it is possible to record the intraureteral pressure at three different levels in the ureter simultaneously. The rate of propagation and direction of the peristaltic waves can thus be determined. Retrograd peristalsis was found in three of the five patients and in one patient and in one patient no peristaltic activity was present at all. The fifth patient demonstrated normal antegrade peristalsis. The findings at renography in the acute stage were in accordance with the ureterometric data.
Peristalsis
Peristaltic pump
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It is well known that the enteric nervous system plays a key role in the generation of gastrointestinal peristaltic movements. Recently, the networks of interstitial cells of Cajal (ICC) have been found to be essential in the generation of spontaneous gastrointestinal movements. However, the role of ICC in the mechanisms involved in the generation of peristaltic movements is still controversial. The aim of the present study was to reveal how pacemaker myenteric ICC (ICC-MY) and the enteric nervous system contribute to the mechanisms involved in the generation of intestinal peristalsis. We compared spontaneous peristaltic movements of the ileum in wild type (WT) mice with those in W/WV mutant mice which are selectively deficient in ICC-MY. Simultaneous recordings were made from both the circular and longitudinal muscle of a 4-cm long segment of ileum under hydrostatic pressure of 0-0.5 cm H2O. Mechanical activity and continuous video-images of the ileum were compared between WT and W/WV mutant mice under control conditions, in the presence of N-nitro-L-arginine methyl ester (L-NAME) and after tetrodotoxin (TTX). In the WT mouse ileum, peristaltic waves to propagate from the oral to the anal end were frequently observed. The frequency of these peristaltic waves and their associated synchronous longitudinal and circular muscle contractions was increased by L-NAME. The peristaltic waves were abolished by TTX. In the W/WV mutant mouse ileum, no peristaltic waves to propagate from the oral to the anal end were observed in control and even after L-NAME, although the local spontaneously generated longitudinal and circular muscle contractions were enhanced by L-NAME. These local contractions were not abolished by TTX. The results presented here suggested that ICC-MY are essential for the generation of spontaneous intestinal peristaltic movements. It is conceivable that ICC-MY may determine the polarity of the excitation of the intestine such that longitudinal and circular muscle contractions propagate from the oral to the anal end of the intestinal segments, although the question of why ICC-MY are necessary for the neural pathways remains unresolved.
Peristalsis
Tetrodotoxin
Enteric Nervous System
Circular muscle
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Swallow-induced esophageal peristalsis is preceded by a wave of inhibition in the esophageal body. The aim of this study was to determine whether a similar wave of inhibition precedes secondary peristalsis. Primary and secondary peristalsis were studied in 6 healthy subjects. Inhibition was visualized as relaxation of an artificial high-pressure zone which was created in the esophageal body by the inflation of a small intraesophageal balloon. Secondary peristaltic contractions induced by injection of 10 ml of air in the proximal esophagus or secondary peristaltic contractions spontaneously occurring after repeated swallowing were preceded by inhibition similar to that observed in primary peristalsis (96.4 +/- 2.8%, 93.2 +/- 4.2% and 91.5 +/- 3.3%) respectively. It is concluded that physiologically triggered secondary peristaltic contractions are preceded by inhibition in the esophageal body.
Peristalsis
Primary (astronomy)
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