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Impaired gastric myoelectrical activity in patients with Parkinson's disease and effect of levodopa treatment.

The aim of this study was to evaluate gastric myoelectrical activity in patients with Parkinson's disease during and after levodopa treatment. Thirteen Parkinson's patients and 13 age-matched Parkinson's-free controls were enrolled. Electrogastrography was used to record gastric myoelectrical activity in all subjects for 30 min before and 30 min after a standard meal. In the group with Parkinson's disease, gastric myoelectrical activity was recorded during both the "on" (with levodopa treatment) and the "wearing-off" (without levodopa for at least 12 hr) periods. Results were as follows. (1) The patients without treatment showed a significantly lower percentage of regular slow waves and a significantly higher instability coefficient of the dominant frequency; (2) the patients showed an absence of the normal postprandial increase in gastric slow wave frequency which was seen in the controls: and (3) treatment with levodopa resulted in an improvement in the fed state, including a marginal increase in the percentage of regular slow waves (P = 0.1), a significant decrease in the instability coefficient, and an enhanced postprandial power increase. In conclusion, patients with Parkinson's disease have reduced slow wave rhythmicity and an impaired postprandial response in gastric myoelectrical activity. These abnormalities may be partially corrected with levodopa treatment in the fed state.

Aged↗

Gastric myoelectric activity in older adults treated with cisapride for gastro-oesophageal reflux disease.

BACKGROUND: The incidence of both gastro-oesophageal reflux disease (GERD) and upper gastrointestinal motility disorders appears to increase with age. However, there is a dearth of data concerning the utility of a prokinetic agent such as cisapride in the treatment of older adults with symptomatic GERD. AIM: To investigate the incidence of electrogastrographic abnormalities in older adults with and without GERD symptoms, as well as the effect of cisapride therapy on symptoms of GERD and electrogastrographic responses. METHODS: We report on 18 older adults with symptomatic GERD and 10 older adult controls (mean ages 71 and 75 years, respectively). Subjects underwent electrogastrographic evaluation pre- and postprandially under baseline conditions and after 1 month of treatment with 10 mg q.d.s. of cisapride. RESULTS: Heartburn frequency and postprandial fullness were both significantly (P < 0. 05) reduced after cisapride treatment. Acid contact time was not significantly changed. The percentage of 2-4 cpm activity in the electrogastrographic analysis was significantly (P < 0.05) increased with cisapride treatment, and the instability coefficient was significantly (P < 0.05) diminished with cisapride treatment. CONCLUSIONS: Enhanced gastric functioning and reduction in heartburn suggest that cisapride is efficacious in the treatment of older adults with symptomatic GERD, and that gastric dysrhythmias and postprandial fullness are resolved with cisapride treatment.

Aged↗

A new nausea model in humans produces mild nausea without electrogastrogram and vasopressin changes.

UNLABELLED: The standard human vection model utilized for nausea has been an optokinetic drum. This model may be difficult to extrapolate to the usual clinical setting. Our goals were to develop an experimental model which could induce low grade nausea in humans and to determine the relationship between mild nausea and changes in the electrogastrogram and plasma vasopressin concentrations. METHODS: Twenty-one volunteers (11 males, mean age: 37 years) participated. At baseline and throughout the study the electrogastrogram was monitored, blood was drawn for vasopressin assay and symptoms of nausea, dizziness and headache were rated on a 0-10-point scale. Subjects were semireclined in a darkened room while viewing moving bars of light rotating at a rate of 85 degrees s-1. Subjects were asked to rate their proneness to motion sickness and their current level of anxiety at baseline. RESULTS: Eight subjects developed mild to moderate (mean: 3.6) nausea during vection. Symptoms of nausea were correlated with a reported history of motion sickness (r = 0.49, P < 0.05) but not with anxiety (r = 0.14, P = 0.54). Degrees of nausea correlated with degrees of dizziness (r = 0.47, P < 0.05) but not with headache (r = 0.29, P = 0.14). Subjects who developed mild nausea were not significantly more likely to exhibit altered electrogastrogram or vasopressin than subjects who did not report nausea. Vasopressin levels during baseline and experimental conditions were highly correlated (r = 0.66, P < 0.005 and r = 0.55 P < 0.005, respectively) with reported baseline anxiety. CONCLUSIONS: (1) This new model in humans induced mild nausea that was unrelated to electrogastrogram and vasopressin abnormalities, (2) high correlation between anxiety and vasopressin suggests that vasopressin may not be directly related to nausea, and (3) these data indicate that onset of nausea mediated centrally can occur without associated electrogastrogram changes.

Adult↗

Visceral perceptions and gastric myoelectrical activity in healthy women and in patients with bulimia nervosa.

UNLABELLED: Bulimia nervosa remains a common eating disorder in young women. Little is known about upper gastrointestinal symptoms or gastric motility in patients with bulimia nervosa. The aim of this study was to measure gastric myoelectrical activity and hunger/satiety and stomach emptiness/fullness before and after a non-nutrient water load and solid-phase gastric emptying in hospitalized patients with bulimia nervosa (n = 12) and in healthy women (n = 13). Gastric myoelectrical activity was measured by means of cutaneous electrodes; visual analogue scales were used to measure perceptions of hunger/satiety and stomach emptiness/fullness. Before and after a standard water load the bulimia patients reported significantly greater stomach fullness and satiety compared with control subjects (P < 0.01). The percentage of gastric myoelectrical power in the normal 3 cpm range was significantly less in bulimics compared with controls. Power in the 1-2 cpm bradygastria range was significantly greater in bulimia patients before and after the water load compared with the control subjects (P < 0.05). Solid-phase gastric emptying studies using radio-isotope-labelled scrambled eggs showed the lag phase was shortened in the bulimic patients (16 +/- 4 min vs 31 +/- 4 min in controls, P < 0.01), but the percentage of meal emptied at 2 h was similar to control values. IN CONCLUSION: bulimia patients had exaggerated perceptions of stomach fullness and satiety in response to water; and abnormal gastric myoelectrical activity and accelerated lag phase of gastric emptying were objective stomach abnormalities detected in hospitalized patients with bulimia nervosa.

Adolescent↗

Changes in pyloric resistance induced by erythromycin.

Erythromycin increases gastric emptying but the characteristics of transpyloric flow and the contribution of pyloric resistance to the mechanisms of increased flow are unknown. Transpyloric outflow and gastroduodenal pressures were studied in eight anaesthetized pigs during intravenous infusion of erythromycin (10 mg kg-1). Erythromycin increased emptying of saline through an increased stroke volume of individual flow pulses (13.7 +/- 1.24 vs. 3.6 +/- 1.30 mL) rather than by decreasing the interval between flow pulses (3.9 +/- 0.55 vs. 3.2 +/- 0.30 pulse.min-1). This flow pattern was associated with more frequent antral contractions of larger amplitude originating from the upper part of the gastric antrum, suppression of isolated pyloric pressure waves and significant reduction of the pyloric resistance to flow (2.3 +/- 0.21 vs. 4.6 +/- 0.46 mmHg mL-1 s-1). The decreased resistance originated from a different temporal relationship between antropyloric pressure event and flow pulses that occurred almost simultaneously during erythromycin.

Animals↗

Effect of meal temperature on the frequency of gastric myoelectrical activity.

It was hypothesized that the transient post-prandial decrease of the dominant frequency in the electrogastrogram (EGG) is related to the temperature of the meal. In a randomized three-period cross-over design. EGG recordings were made in 10 healthy volunteers. A liquid meal (36 kcal, 300 mL) was ingested at either 4, 37 or 55 degrees C. The changes in the dominant EGG frequency that occurred in the first 25 min postprandial were calculated using running spectrum analysis. After the meal a transient shift in frequency was seen, which was significantly greater after the cold meal than after the other meals (P < 0.001), with a greater decrease in the dominant frequency (4 degrees C: -0.75 [-0.92(-)-0.68], 37 degrees C: -0.34 [-0.51(-)-0.18], 55 degrees C: -0.30 [-0.45(-)-0.12] cpm; P = 0.020) and a longer duration (4 degrees C: 16 [13-19], 37 degrees C: 12 [6-14], 55 degrees C: 5 [3-8] min; P = 0.014). No differences were found between the 37 degrees C and 55 degrees C meals, the power ratios or the number of dysrhythmias. The magnitude of the postprandial shift in frequency of gastric myoelectrical activity depends on the temperature of the meal. Meal temperature should be taken into account in studies on postprandial gastric motility.

Adult↗

Postprandial peristalsis in the human duodenum.

MMC-related retroperistalsis is a cyclical phenomenon in the duodenum linked to phase III. The aim of this study was to elucidate the direction of propagation of juxtapyloric duodenal pressure waves in the postprandial state in healthy humans and to compare with the contractions in the interdigestive phase II. Antroduodenal manometry was performed in 11 healthy subjects. Individual pressure waves propagating along a 6-cm duodenal segment were analysed with respect to the proportions of antegrade and retrograde propagation in the four duodenal subsegments (D1-D2) to (D4-D5), each subsegment being 15 mm. A test meal was given 30 min after a phase III had passed and motility recording continued for 60 min after the meal. During both the first and the second 30-min period of postprandial recording the proportion of retrograde pressure waves was larger just distal to the pylorus, (D1-D2), 40% (23-68) and 50% (23-68), respectively, compared to the distal part, (D4-D5), of the duodenal segment, 29% (12-30) and 10% (10-24), respectively (P < 0.05 and 0.01). In contrast, during late phase II of the interdigestive state antegrade pressure waves predominated in all four duodenal subsegments. We conclude that in the postprandial state a high proportion of the duodenal pressure waves (40-50%) is retrograde in the immediate juxtapyloric area while antegrade contractions predominate at a distance 5-6 cm distal to the pylorus. These manometric data together with recent observations of postprandial transpyloric liquid flow, indicate that retrograde duodenogastric propelling of contents may be an important determinant for the gastric emptying rate.

Adult↗

Effects of sympathetic nerve stimulation on membrane potential in the circular muscle layer of mouse distal colon.

Little is known about the effects of sympathetic nerve stimulation on the membrane potential of colonic smooth muscle. In the distal colon of the mouse, intracellular microelectrodes were used to record the effects of lumbar colonic (LCN) and intermesenteric nerve (IMN) stimulation on circular muscle membrane potential in vitro. A two-compartment organ bath was used to selectively perfuse the colon and inferior mesenteric ganglion (IMG). In the presence of nifedipine (1-2 microM) (to the colonic compartment only), spontaneous depolarizations (myoelectric complexes, MCs) were recorded about every 4 min. MCs consisted of a prolonged burst of rapid oscillations in membrane potential (approximately 2 Hz) that were superimposed on a slow depolarization (mean amplitude 12 mV). Single electrical stimuli (600 microseconds duration) delivered to the LCN or IMN did not elicit a detectable change in the membrane potential. However, trains of stimuli (e.g., 60 pulses at 10-20 Hz) to the LCN or IMN during the intervals between MCs evoked a depolarization (with superimposed action potentials in the absence of nifedipine). Trains of stimuli delivered during the plateau phase of the MC reduced or abolished the rapid oscillations, without a further membrane depolarization. The MC period was unaffected by stimulation of the IMN or LCN. Responses were abolished by the selective perfusion of guanethidine (1 microM) to the colon, or by severing the LCN. Hexamethonium (500 microM) (to the colon) abolished MCs, induced sustained depolarization and attenuated the amplitude of the sympathetic depolarizations by 74%. In hexamethonium, sympathetic responses remained attenuated when the membrane of the circular muscle was repolarised by sodium nitroprusside (1 microM). Immunohistochemical studies of the colon revealed intense immunoreactivity for tyrosine hydroxylase in the myenteric plexus but not in the circular muscle layer. It is suggested that responses to sympathetic nerve stimulation in the circular muscle layer of the mouse colon are secondary to actions on the enteric nervous system.

Animals↗

High-resolution analysis of the duodenal interdigestive phase III in humans.

To study the spatial organization of the propagating pressure waves of duodenal phase III, we performed fasting antroduodenal high-resolution manometry with a 16-channel catheter in 12 healthy subjects. The phase III pressure waves diverged in an anterograde and retrograde direction from the start site of each pressure wave. The pressure waves maintained this configuration as the activity front moved distally in the duodenum. The start site of the pressure waves moved gradually to a point approximately 12 cm (median) distal to the pylorus and remained at this point for about 40% of the phase III time before moving further distally. The length of retrograde pressure wave propagation increased to 6 cm (median) as the pressure wave origin moved aborally to a point 10-14 cm distal to the pylorus, and then decreased when the origin of pressure waves reached the distal end of the duodenum. Bidirectional pressure waves dominated in both retrograde and anterograde activity fronts. Three pressure-wave mechanisms behind the duodenal phase IV were observed. Isolated pyloric pressure waves were absent during late duodenal phase III retroperistalsis. Thus, a number of new features of the duodenal phase III-related motility were observed using high-temporospatial resolution recordings.

Adult↗

Analysis of motor patterns in the isolated guinea-pig large intestine by spatio-temporal maps.

We investigated and quantified the spontaneous patterns of motility in the isolated guinea-pig proximal and distal colon taken from adult animals. During spontaneous emptying, profiles of proximal and distal colon were recorded with a video camera, and image analysis was used to construct spatio-temporal maps of the motions of the intestinal wall. Four patterns of motility were recorded. In the proximal colon there were neurally mediated contractions that propagated in the aboral direction at 4.1 mm s(-1), gently pushing the soft contents aborally; these are likely to represent spontaneous peristaltic behaviour. A second pattern, insensitive to tetrodotoxin (TTX; 0.6 microM), consisted, in both oral and aboral propagation, of shallow contractions of the circular muscle (ripples). These contractions propagated aborally at 2.8 +/- 0.45 mm s(-1) and orally at 2.03 +/- 0.31 mm s(-1) (n=10). Of these TTX-resistant contractions, 22.5% propagated both orally and aborally from a common origin. The orally propagated component of these myogenic contractions is likely to correspond to the antiperistalsis widely described in the proximal colon. In the distal colon, two patterns of motor activity were observed. One, induced by natural or artificial pellets, consisted of peristaltic contractions that pushed the pellets aborally at 0.8 mm s(-1) and expelled a pellet every 108 s. In the interval between pellet propulsion and after the distal colon had emptied all of its pellets a second, nerve-mediated pattern of motor activity, consisting of clusters of annular circular muscle contractions separated by short dilated regions, slowly propagated aborally at 0.3 mm s(-1). Both of these motor patterns were abolished by TTX (0.6 microM). A latex balloon, inserted at the oral end of the empty isolated distal colon and inflated to a size similar to faecal pellets, was propelled at 1.4 mm s(-1). Epoxy resin-covered natural pellets were propelled at a similar speed of 1.6 mm s(-1). Our data revealed that myogenic and neurogenic patterns of propagated contractions in the colon occur in isolated preparations and are involved in emptying the colon.

Animals↗

Influence of naloxone on gastric emptying of solid meals, myoelectrical gastric activity and blood hormone levels in young healthy volunteers.

There is considerable evidence that opioid mechanisms are involved in the mediation of pyloric motor responses that in turn regulate gastric emptying. The purpose of this randomized, placebo-controlled crossover study was to investigate the effect of naloxone on gastric emptying of a solid meal, gastric myoelectrical activity and the postprandial release of gastrointestinal peptides and neuropeptides in 20 healthy volunteers. Naloxone was administered as an intravenous bolus, followed by continuous infusion according to an intravenous dosing nomogram. Gastric emptying time was evaluated by scintigraphy and gastric myoelectrical activity was evaluated by cutaneous electrogastrography. Naloxone did not significantly alter gastric half-emptying time and postprandial dominant gastric electrical frequency compared with placebo. It also did not significantly change the plasma levels of several peptide hormones with the exception of neuropeptide Y, which was significantly increased (P = 0.001). In conclusion, in doses that influence human intestinal motility, naloxone had no effect on gastric motility and release of several peptide hormones in healthy male volunteers. The importance of the isolated increased neuropeptide Y plasma level needs further investigation.

Adult↗

Detection of gastric slow wave uncoupling from multi-channel electrogastrogram: validations and applications.

Current methodology of single channel electrogastrography is unable to detect coupling or uncoupling of gastric slow waves, which is crucial for gastric emptying. In this study, a new methodology, called cross-spectral analysis method, was established to compute the coupling percentage of multi-channel gastric slow waves recorded using serosal electrodes and electrogastrogram (EGG). Two experiments were performed to validate the method and demonstrate its applications in clinical research. In experiment 1, simultaneous recordings of gastric slow waves were made in five dogs from serosal electrodes and cutaneous electrodes. In experiment 2, four-channel fasting EGGs were made in 10 volunteers for 30 min during waking and 30 min during non-rapid eye movement (REM) sleep. The validation study (experiment 1) showed that the slow wave coupling calculated from the EGGs was correlated with that computed from the serosal recordings. The gastric slow wave coupling percentages detected from both serosal and cutaneous recordings were significantly impaired during vasopressin infusion (6.3 +/- 2.6 vs 62.4 +/- 6.3, P < 0.001 for serosal recordings; 6.7 +/- 3.0 vs 57.2 +/- 2.7, P < 0.001 for cutaneous recordings), and the coupling percentages respectively calculated from serosal and cutaneous recordings were significantly correlated during the baseline recording period (R = 0.922, P < 0.05) and vasopressin infusion period (R = 0.916, P < 0.05). In experiment 2, the gastric slow wave became less coupled when healthy volunteers fell asleep. The percentage of slow wave coupling calculated from the EGGs was 68.2 +/- 17.9% during waking but 41.9 +/- 20.8 during non-REM sleep (P < 0.05). The method developed in this study is reliable for the detection of slow wave uncoupling from multi-channel EGGs. Gastric slow wave coupling is impaired during vasopressin infusion and sleep. These data suggest that this method has potential applications in physiological and clinical studies.

Adult↗

Biomagnetic detection of gastric electrical activity in normal and vagotomized rabbits.

We recorded the vector magnetogastrogram (MGG) due to gastric electrical activity (GEA) in normal rabbits using a Superconducting QUantum Interference Device (SQUID) magnetometer and measured the degree of correlation of the MGG with 24 channels of serosal electrodes. The vector magnetometer allows us to non-invasively record three orthogonal magnetic field components and project the recorded magnetic field vector into arbitrary directions. We optimized the magnetic field vector direction to obtain the highest possible correlation with each serosal electrode recording. We performed a vagotomy and examined spatial and temporal changes in the serosal potential and in the transabdominal magnetic field. We obtained spatial information by mapping the recorded signals to the electrode positions in the gastric musculature. Temporal evidence of uncoupling was observed in spectral analyses of both serosal electrode and SQUID magnetometer recordings. We conclude that non-invasive recordings of the vector magnetogastrogram reflect underlying serosal potentials as well as pathophysiological changes following vagotomy.

Animals↗

Manometric techniques for the evaluation of colonic motor activity: current status.

Colonic motility disorders are common conditions. However, our understanding of normal, and, consequently, pathological motor function of the colon remains limited, mainly due to the relative inaccessibility of this organ for study. Investigation of colonic motility may encompass one or more of the four separate components (myoelectric activity, phasic and tonic contractile activity and movement of intraluminal content) using electrophysiological, manometric or transit studies. Although transit studies provide the best 'functional' appreciation of colonic motor activity, and are the only techniques used in contemporary clinical practice, manometric methods are becoming increasingly popular, as they allow a direct study of colonic contractile activity over prolonged periods. To date, the majority of studies have been limited to the pelvic colon by a retrograde (per rectal) approach; however, recent technological advances have facilitated 'pan-colonic' investigation. This review concentrates on manometry of the human colon proximal to the sigmoid, and includes evaluation of both phasic and tonic motor activity, by utilization of perfused-tube and solid-state manometric catheters, and also the electronic barostat. Methodological techniques, experimental protocols and the analysis and interpretation of recorded data are critically explored, and a contemporary classification of colonic contractile activities is presented.

Animals↗

Colonic motor activity in slow-transit idiopathic constipation as identified by 24-h pancolonic ambulatory manometry.

Colorectal motor activity in slow-transit idiopathic constipation has not been fully evaluated under physiological conditions. The aim of this study was to evaluate colorectal motor activity in chronic idiopathic constipation using 24-h ambulant pancolonic manometry. Ten healthy volunteers (six females) 19-31 years of age, and eight females 25-46 years of age with slow-transit idiopathic constipation were studied. Motor activity was measured using two custom-made silicone-coated catheters, each with five solid-state pressure transducers. Bowel preparation or sedation was not used. Frequency of high-amplitude propagated contractions was reduced in chronic idiopathic constipation, median 1.9/24 h vs 6/24 h (P = 0.01). Contractile frequency of low-amplitude complexes was reduced throughout the colon in slow-transit idiopathic constipation (P < 0.0001). The interval between contractile complexes was reduced in the transverse colon and splenic flexure (P < 0.0001). This study demonstrates that colonic motor activity is abnormal in slow-transit idiopathic constipation; decreased motor activity leads to a reduction in propulsion of intraluminal contents.

Adult↗

Mediation of transcatheter arterial chemoembolization induced gastric slow-wave dysrhythmia by endogenous prostaglandin.

BACKGROUND AND AIMS: In recent years, gastric slow-wave dysrhythmias induced by transcatheter arterial chemoembolization (TACE) have been observed. Enhanced endogenous prostaglandin may be a possible mechanism for the myoelectrical changes. The aim of this study was to evaluate whether the gastric slow-wave dysrhythmias induced by TACE may be mediated by ketoprofen, a prostaglandin synthesis inhibitor. METHODS: Twenty-three patients with hepatocellular carcinoma (HCC) admitted for TACE were enrolled. A follow-up TACE was scheduled to take place 2 months later. During the next admission for TACE, 50 mg of ketoprofen was given intramuscularly 12 h for 3 days, beginning 48 h before TACE, as premedication. Cutaneous electrogastrography (EGG) was performed before and within 24 h after TACE. RESULTS: The results showed that the change in the fasting EGG parameters after TACE without premedication was not statistically significant. However, the postprandial EGG parameters, including the dominant frequency (DF); the percentages of DF in the normal, bradygastric and tachygastric range; along with the dominant frequency instability coefficient, deteriorated significantly after the procedure (P < 0.01). After the follow-up TACE with ketoprofen premedication, neither the fasting nor postprandial EGG parameters in the control group changed significantly. CONCLUSIONS: Gastric slow-wave dysrhythmias induced by TACE may be mediated by ketoprofen, a prostaglandin synthesis inhibitor, in HCC patients. However, the improvement in the gastric myoelectrical activity does not eliminate the degree of nausea/vomiting after TACE.

Adult↗

Stomach myoelectrical response of patients with gastroesophageal reflux disease receiving omeprazole treatment.

BACKGROUND AND AIM: Proton pump inhibitor treatment is effective for gastroesophageal reflux disease (GERD). It is unknown whether these agents effect any change in the stomach myoelectricity of GERD patients. Electrogastrographic (EGG) recording was used to study the probable effect of omeprazole on GERD patients. METHODS: Nineteen endoscopically confirmed GERD patients and 38 dyspepsia-free controls were invited to receive EGG recording. After daily omeprazole treatment for 4 weeks, the symptomatic response of GERD patients was scaled, healing of erosive esophagitis was endoscopically assessed, and EGG recording was repeated for comparison. RESULTS: Before treatment, GERD patients and controls displayed similar dominant frequency, whereas the former had higher dominant power compared with controls, either in fasting (29.2 +/- 6.0 dB compared with 25.3 +/- 3.8 dB, P < 0.01) or postprandial (31.9 +/- 5.6 dB compared with 27.7 +/- 3.8 dB, P < 0.001) recording. They also had diminished percentile normal rhythm (2-4 c.p.m.), irrespective of fasting (40.2 +/- 14.5% compared with 65.8% +/- 23.5%, P < 0.001) or postprandial (47.5 +/- 23.3% compared with 77.9 +/- 16.8%, P < 0.001) recording. After omeprazole treatment, healing was achieved in 12 patients (63.2%). Among the abnormal EGG parameters, only the postprandial percentile normal rhythm was restored (47.5 +/- 23.3% compared with 65.2 +/- 20.8%, P < 0.01). CONCLUSIONS: Gastroesophageal reflux disease patients may have obvious dysrhythmia and higher myoelectrical power. Effective omeprazole treatment only improves the postprandial myoelectrical regularity, whereas abnormal EGG parameters remain impaired.

Adult↗