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Ureteropelvic junction obstruction
Published in Mark Davenport, James D. Geiger, Nigel J. Hall, Steven S. Rothenberg, Operative Pediatric Surgery, 2020
Lauren E. Corona, Kate H. Kraft
Obstruction most commonly results from an intrinsic defect in the smooth muscle layer of the UPJ. External compression and blockage by aberrant renal vessels and adhesive bands occur in approximately one-third of cases, and often a combination of external compression and intrinsic pathology exists. Light microscopy demonstrates that abnormal smooth muscle architecture and increased fibrosis are present in obstructed UPJs. Electron microscopy further shows disruption of the intercellular junctions needed to coordinate the transmission of peristaltic waves.
StomachGastric Secretions, Motility, Digestion and Vomiting
Published in Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal, Principles of Physiology for the Anaesthetist, 2020
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal
Peristaltic contractions are initiated near the border of the fundus and the body and progress to the pylorus, thus producing a peristaltic wave that propels food towards the pylorus. The peristaltic contractions are produced by changes in membrane potential, called slow waves. The gastric slow waves (basal electrical rhythm), arising from pacemaker cells within the longitudinal muscle, consist of depolarizing waves (from −60 mV to −30 mV) and originate from specialized cells within the muscle layers called the interstitial cells of Cajal. An area along the greater curvature of the proximal stomach generates the greatest frequency (about three cycles per minute) and acts as the dominant pacemaker that drives the more distal areas at this rhythm.
Upper Gastrointestinal Surgery
Published in Gozie Offiah, Arnold Hill, RCSI Handbook of Clinical Surgery for Finals, 2019
Manometry➢ Absence of peristaltic waves in oesophagus.➢ High resting intra-oesophageal pressure, impaired relaxation.➢ Normal resting pressure is 0-30 mmHg.
Digital rectal stimulation as an intervention in persons with spinal cord injury and upper motor neuron neurogenic bowel. An evidenced-based systematic review of the literature
Published in The Journal of Spinal Cord Medicine, 2021
Mary Elizabeth S. Nelson, Merle Orr
Two studies focused solely on DRS as an intervention, one directly, and one through the application of pressure to the rectum with extrapolation of findings to DRS. The first study, Korsten et al.8 included 6 males with SCI and UMN-NB, age 44–55. Manometric evaluation of peristaltic contraction via insertion of a probe into the left colon was performed. Subjects served as their own controls and were evaluated before and after DRS was applied. The mean number of peristaltic waves per minute significantly increased during and after DRS (P = 0.05). Full evacuation of the bowels was noted after three to five cycles of DRS, with the longest duration of time to complete evacuation being 13 min. Shafik et al.'s9 study was a controlled randomized study of the effect of dilatation of the anal canal by a balloon-tipped catheter on rectal pressure. Eighteen healthy volunteers (10 men and 8 women,) and nine patients with SCI and UMN-NB (6 men and 3 women,) were evaluated. Repeated measures were taken before and after pudendal nerve block to paralyze the external anal sphincter to isolate the effects of internal anal sphincter dilation from external. The researcher found that distention of the anal canal resulted in a significant (P < 0.001) pressure rise. This data was extrapolated to simulate DRS on rectal pressures and the evacuation of bowels.
Critical review of the evidence for a causal association between exposure to asbestos and esophageal cancer
Published in Critical Reviews in Toxicology, 2019
Michael K. Peterson, Isaac Mohar, Thuy Lam, Travis J. Cook, Anna M. Engel, Heather Lynch
The primary function of the esophagus is to transport swallowed food to the stomach (Goyal and Chaudhury 2008; Widmaier et al. 2008). The upper esophageal sphincter (the ring of skeletal muscles that surrounds the esophagus just below the pharynx), prevents air from entering the esophagus when a person is not swallowing (i.e. while breathing). During the esophageal phase of swallowing, the upper esophageal sphincter relaxes, allowing food to pass it, then contracts again (Widmaier et al. 2008; ACS 2017). The food moves down the esophagus toward the stomach “by a progressive wave of muscle contractions that proceeds along the esophagus” (peristaltic waves) (Widmaier et al. 2008, p. 544); it takes 8–10 s for one peristaltic wave to reach the stomach (Mashimo and Goyal 2006). The lower esophageal sphincter remains open and relaxed during this period of swallowing. After the food enters the stomach, the lower esophageal sphincter closes, keeping stomach acid and digestive enzymes out of the esophagus (Widmaier et al. 2008; ACS 2017). In some people, the lower esophageal sphincter is less effective, allowing gastric contents to reflux into the esophagus, causing GERD, heartburn, and, in more severe cases, ulceration, scarring, obstruction, or perforation of the lower esophagus (Widmaier et al. 2008).
Constructing artificial urinary conduits: current capabilities and future potential
Published in Expert Review of Medical Devices, 2019
Jan Adamowicz, Shane V. Van Breda, Tomasz Kloskowski, Kajetan Juszczak, Marta Pokrywczynska, Tomasz Drewa
Cajal-like cells (ICC–LC) distributed within the urinary tract wall act as electrical pacemaker cells that trigger and drive synchronous smooth muscle contraction [50]. Peristaltic waves are generated in the renal pelvis and propagate down the urinary tract up to the urethra by Cajal like cells lying beneath the urothelial layer. Although in vitro isolation and culture of ICC–LC from the urinary tract has not been reported yet, the interstitial cells derived from the gastrointestinal wall might serve as an alternative. An artificial urinary conduit might also resemble an intestine wall; the recent advances in the field of urological and gastrointestinal tissue engineering should be interpreted as interdisciplinary. Bitar et al. co-cultured smooth muscle cells with intestinal organoid units to produce circular constructs that were wrapped around tubular collagen scaffolds to resemble the native intestine wall [51]. Mechanical evaluation exhibited a spontaneous contractility pattern within the construct. Even if we learn how to isolate Cajal like cells, in vitro production of a functional network with active pacemaker units controlling peristaltic waves seems to be far beyond our biotechnological development level. A more accessible option might be the replacement of a pacemaker network by an artificial interface based on conductive biomaterial. In this setting impulses generated by the external device would activate smooth muscle contraction in a peristaltic manner.