Stimulation of extrinsic sympathetic nerves differentially affects neurogenic motor activity in guinea pig distal colon.

The speed of pellet propulsion through the isolated guinea pig distal colon in vitro significantly exceeds in vivo measurements, suggesting a role for inhibitory mechanisms from sources outside the gut. The aim of this study was to investigate the effects of sympathetic nerve stimulation on three different neurogenic motor behaviors of the distal colon: transient neural events (TNEs), colonic motor complexes (CMCs), and pellet propulsion. To do this, segments of guinea pig distal colon with intact connections to the inferior mesenteric ganglion (IMG) were set up in organ baths allowing for simultaneous extracellular suction electrode recordings from smooth muscle, video recordings for diameter mapping, and intraluminal manometry.

Identifying Types of Neurons in the Human Colonic Enteric Nervous System.

Distinguishing and characterising the different classes of neurons that make up a neural circuit has been a long-term goal for many neuroscientists. The enteric nervous system is a large but moderately simple part of the nervous system. Enteric neurons in laboratory animals have been extensively characterised morphologically, electrophysiologically, by projections and immunohistochemically.

Mechanisms underlying initiation of propulsion in guinea pig distal colon.

Colonic motor complexes (CMCs) are a major neurogenic activity in guineapig distal colon. The identity of the enteric neurons that initiate this activity is not established. Specialized intrinsic primary afferent neurons (IPANs) are a major candidate.

Characterization of alternating neurogenic motor patterns in mouse colon.

Background: Colonic motor complexes (CMCs) have been widely recorded in the large intestine of vertebrates. We have investigated whether in the smooth muscle, a single unified pattern of electrical activity, or different patterns of electrical activity give rise to the different neurogenic patterns of motility underlying CMCs in vitro.

Methods: To study differences of the CMCs between proximal and distal colon, we used a novel combination of techniques to simultaneously record muscle diameter and force at multiple sites along the whole mouse colon ex vivo.

Postoperative ileus-An ongoing conundrum.

Background: Postoperative ileus is common and is a major clinical problem. It has been widely studied in patients and in experimental models in laboratory animals. A wide variety of treatments have been tested to prevent or modify the course of this disorder.

Intrinsic sensory neurons provide direct input to motor neurons and interneurons in mouse distal colon via varicose baskets.

Connections from intrinsic primary afferent neurons (IPANs), to ascending motor and interneurons have been described in guinea pig colon. These mono- and polysynaptic circuits may underlie polarized motor reflexes evoked by local gut stimulation. There is a need to translate findings in guinea pig to mouse, a species increasingly used in enteric neuroscience.

Omental infarction mimicking cholecystitis.

Omental infarction can be difficult to diagnose preoperatively as imaging may be inconclusive and patients often present in a way that suggests a more common surgical pathology such as appendicitis. Here, a 40-year-old Caucasian man presented to casualty with shortness of breath and progressive right upper abdominal pain, accompanied with right shoulder and neck pain. Exploratory laparoscopy was eventually utilised to diagnose an atypical form of omental infarction that mimics cholecystitis.

Transgene expression and transgene-induced silencing in diploid and autotetraploid Arabidopsis.

Previous studies have suggested that transgene expression in plants can be affected by ploidy. Here we show that three different transgenes, a reporter transgene, an antisense transgene, and a hairpin RNA (hpRNA) transgene, are all expressed at a lower level in autotetraploid (4n) than in diploid (2n) Arabidopsis. RNA silencing of two endogenous genes was induced by the antisense and hpRNA transgenes and this silencing is significantly less effective in 4n than in 2n Arabidopsis; furthermore, the reduced silencing in 4n Arabidopsis correlated with reduced accumulation of silencing-inducer RNAs.