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.

Sequestration and inhibition of Daxx-mediated transcriptional repression by PML

PML fuses with retinoic acid receptor alpha (RARalpha) in the t(15;17) translocation that causes acute promyelocytic leukemia (APL). In addition to localizing diffusely throughout the nucleoplasm, PML mainly resides in discrete nuclear structures known as PML oncogenic domains (PODs), which are disrupted in APL and spinocellular ataxia cells. We isolated the Fas-binding protein Daxx as a PML-interacting protein in a yeast two-hybrid screen. Biochemical and immunofluorescence analyses reveal that Daxx is a nuclear protein that interacts and colocalizes with PML in the PODs. Reporter gene assay shows that Daxx drastically represses basal transcription, likely by recruiting histone deacetylases. PML, but not its oncogenic fusion PML-RARalpha, inhibits the repressor function of Daxx. In addition, SUMO-1 modification of PML is required for sequestration of Daxx to the PODs and for efficient inhibition of Daxx-mediated transcriptional repression. Consistently, Daxx is found at condensed chromatin in cells that lack PML. These data suggest that Daxx is a novel nuclear protein bearing transcriptional repressor activity that may be regulated by interaction with PML.

Noninvasive feature-based detection of delayed gastric emptying in humans using neural networks

Radioscintigraphy is currently the gold standard for gastric emptying test which involves radiation exposure and is considerably expensive. We present a feature-based detection approach using neural networks for the noninvasive diagnosis of delayed gastric emptying from the cutaneous electrogastrogram (EGG). Simultaneous recordings of the EGG and scintigraphic gastric emptying test were made in 152 patients with symptoms suggestive of delayed gastric emptying. Spectral analyses were performed to derive EGG parameters which were used as the input of the neural network. The result of scintigraphic gastric emptying was used as the gold standard for the training and testing of the neural network. A correct classification of 85% (a specificity of 89% and a sensitivity of 82%) was achieved using the proposed method.

Differential mechanisms of nuclear receptor regulation by receptor-associated coactivator 3

Steroid and nuclear receptor coactivators (NCoAs) have been implicated in the regulation of nuclear receptor function by enhancing ligand-dependent transcriptional activation of target gene expression. We have previously isolated receptor-associated coactivator 3 (RAC3), which belongs to the steroid receptor coactivator family. In this study, we investigated the differential mechanisms by which RAC3 interacts with and modulates the transcriptional activity of different nuclear receptors. We found that the vitamin D receptor (VDR) and estrogen receptor beta interact with different alpha-helical LXXLL motifs of RAC3. Peptides corresponding to these motifs have diverse affinities for the VDR and estrogen receptor beta, and mutation of specific motifs differentially impairs the ability of RAC3 to interact with these receptors in vitro. Consequently, these mutations inhibit the enhancement of transcriptional activation by these receptors in vivo. Furthermore, we found that the activation function-2 (AF-2) domain of the retinoid X receptor interferes with RAC3 binding to a DNA-bound VDR/retinoid X receptor (RXR) heterodimer, whereas the VDR AF-2 domain is required for this interaction. These results suggest a receptor-specific binding preference for the different LXXLL motifs of RAC3, which may provide flexibility for RAC3 to differentially regulate the function of different nuclear receptors.

Enhanced postprandial gastric myoelectrical activity after moderate-intensity exercise

OBJECTIVE

The aim of this study was to investigate the change of postprandial gastric myoelectrical activity and its relation with vagal activity after exercise.

METHODS

Nine subjects were studied in two sessions. In the control session, gastric myoelectrical activity was recorded using electrogastrography (EGG) for 30 min in the fasting state and 60 min after a test meal. In the exercise session, after the baseline recording of both the EGG and electrocardiogram (ECG), the subject was put on a cycle ergometer for exercise until reaching 50% of the maximum age-predicted heart rate for 10 min. The test meal was then given and the recording was resumed for 60 more minutes. Spectral analyses were performed on both the EGG and the heart rate variability derived from the ECG.

RESULTS

The postprandial increment of the dominant power (p<0.05) and the percentage of the 2-4 cpm slow waves (p = 0.01) were significantly higher with exercise. The standard deviation of the postprandial dominant frequency was significantly decreased (more stable slow waves) with exercise (p<0.04). While cardiac vagal activity was significantly decreased after the meal, exercise did not significantly affect the postprandial change.

CONCLUSIONS

Gastric slow waves become more regular, more stable, and of higher amplitude after exercise, and this enhancement is probably not mediated via the vagal pathway.

Distension-induced myoelectrical dysrhythmia and effect of intestinal pacing in dogs

The aims of this study were to investigate the effect of duodenal distension on intestinal myoelectrical activity and to investigate whether intestinal pacing was able to reverse the effects of distension. Six female hound dogs with four pairs of electrodes on the proximal jejunum were involved in this study. The protocol consisted of 30 min of recording of jejunal myoelectrical activity as baseline and 90 min of recording during distension. Intestinal pacing was performed during the second 30 min of distension. Duodenal distension severely impaired intestinal myoelectrical activity. The percentage of normal slow waves was reduced from 90.8+/-8.4% at baseline to 73.8+/-10.2%, 57.2+/-11.4%, and 53.7+/-16.0% during the first, second and third 30 min of distension (P<0.05, ANOVA). The dominant power was similarly decreased and the minute-by-minute variation of dominant frequency was significantly increased after distension. Intestinal pacing reversed distension-induced dysrhythmia. The percentage of normal slow waves during the 30 min of distension with pacing was significantly higher than the corresponding 30 min of distension without pacing (88.5+/-6.6% vs. 57.2+/-11.4%, P<0.03). It was concluded that intestinal pacing can normalize distension-induced dysrhythmia and has a potential as a future therapeutic modality for intestinal motor disorders.

Prototype algorithm for automated determination of gastric slow wave characteristics

An algorithm for determining the frequency and propagation time of the gastric slow wave has been designed for integration into a demand gastric pacing system. The algorithm analyses the serosal activity in both the time and frequency domains, and the results are compared to produce a conclusion only when the values are within 5% of each other. Thus, the probability of inappropriate intervention is reduced, at the expense of unidentified segments. The system is verified by comparing the conclusions produced by the algorithm with conclusions from hand analysis of seven canine and one human serosal recordings. The algorithm correctly identifies the slow-wave frequency in the distal portion of the stomach for 90% of the segments, while producing no incorrect results. Slow-wave propagation times in the antrum are correctly identified for 84% of the segments, with no incorrect identifications.

[Safety analysis for astronaut and the personal protective equipment]

Objective. To analyze and study astronaut and his personal equipment safety. Method. Three of the most widely used approaches, failure mode and effect analysis (FMEA), fault tree analysis (FTA) and system hazards analysis (SHA) were used. Result. It was demonstrated that astronaut and the personal equipment are subjected to various potential hazards, such as human errors, astronaut illness, fire or space suit emergency decompression, etc. Their causes, mechanisms, possible effects and criticality of some critical potential hazards were analyzed and identified in more details with considerations of the historic accidents of manned spaceflight. And the compensating provisions and preventive measures for each hazard were discussed. Conclusion. The analysis study may be helpful in enhancing the safety of the astronaut and its personal protective equipment.

Gastric myoelectric activity in patients with end-stage liver disease

BACKGROUND

Abnormalities of gastrointestinal motility and transit time have been reported in association with end-stage liver disease. Motility abnormalities could be routinely studied if a simple noninvasive test were available. The electrogastrogram is a cutaneous measure of gastric myoelectric activity and correlates well with serosal recordings of gastric myoelectric activity. The aim of this study was to evaluate gastric myoelectric activity in patients with end-stage liver disease.

METHODS

Fourteen patients with end-stage liver disease had gastric myoelectric activity measured with the electrogastrogram. An electrogastrogram was considered abnormal when normal gastric slow waves were seen less than 70% of the time or there was no increase in the electrogastrogram amplitude after a meal.

RESULTS

Abnormal electrogastrograms were present in 8 of 14 (57%) end-stage liver disease patients.

CONCLUSIONS

Abnormal gastric myoelectric activity is common in end-stage liver disease.

Postprandial response of jejunal slow waves and mediation via cholinergic mechanism

The postprandial characteristics of jejunal myoelectrical activity and its mediation via cholinergic nerves were investigated in this study. Four pairs of bipolar electrodes were implanted on the serosa of the proximal jejunum of nine female hound dogs (14-22 kg). In the control session, the recording of jejunal myoelectrical activity was made for 30 min in the fasting state and for 90 min after a solid meal (0.45 kg, 838 kcal). The study session followed the same protocol except that a bolus of 0.25 mg/kg atropine was injected intravenously 30 min after the meal. Computerized spectral analysis was performed to calculate the frequency, power, and percentage of 17-22 cycles/min (cpm) slow waves. A special artificial neural network program was applied to compute the spike bursts superimposed on slow waves. All data were expressed as mean +/- SE. The postprandial frequency of the jejunal slow waves was significantly increased from 18.42 +/- 0.28 cpm in the fasting state to 18.95 +/- 0.22, 19.28 +/-0.23, and 19.28 +/- 0.22 cpm during the first, second, and third 30-min periods after the meal (all P < 0.03 in comparison with the fasting state). The percentage of the slow waves superimposed with spike bursts was increased from 19.33 +/- 3.90% at fasting state to 35.16 +/-2.76%, 32.87 +/- 4.06%, and 34.88 +/- 3.51% during the first, second, and third 30-min periods after the meal (all P < 0.03 in comparison with fasting state). Atropine abolished the postprandial increases in the frequency of slow waves and the number of spike bursts. No significant postprandial changes in the power and the percentage of 17-22 cpm slow waves were observed. In conclusion, the postprandial response of the jejunal slow waves after a solid meal presents as an increase of the frequency of slow waves and the number of the spike bursts which can be abolished by atropine, and the postprandial response of the jejunal slow waves is a neural reflex dominantly mediated via vagal cholinergic nerves.

Detection of gastric slow wave propagation from the cutaneous electrogastrogram

The gastric slow wave is originated in the proximal stomach and propagates distally toward the pylorus. It determines the maximum frequency and propagation of gastric contractions. The aim of this study was to detect the propagation of the gastric slow wave from the surface electrogastrogram (EGG). The study was performed in 11 healthy subjects of normal weight. Gastric myoelectrical activity was recorded for 1 h in the fasting state with the use of a specially designed multichannel recording device that was composed of four identical amplifiers with cutoff frequencies of 1.8 and 16.0 cycles/min. Four active electrodes were placed on the abdomen along the gastric axis and were connected to a common reference electrode placed near the xiphoid process, yielding four-channel bipolar EGG signals. Cross-covariance analysis was performed to compute the time lag among the four channels. There was a time lag in EGG waveform between channels 1 and 4 (9.6 +/- 1.1 s); the average time during which the time lag was observed (>/=3 s) was 89.9 +/- 9.0%. There was a significant difference in the time lag among different adjacent channels (P < 0.04); the time lag observed between channels 3 and 4 was significantly smaller than that between channels 1 and 2 (P < 0.03). No correlation was found between the body mass index and the time lag between channels 1 and 4 (r = -0.31, P = 0.3). It was concluded that, with a multichannel recording device with identical multiamplifiers and an appropriate arrangement of abdominal electrodes, the propagation of the gastric slow wave could be identified from the EGG in healthy subjects. This method may be used to detect the coupling of the gastric slow wave noninvasively.

Disruption of normal gastric myoelectric functioning by sleep

STUDY OBJECTIVES

The aim of this study was to assess the effects of sleep on gastric myoelectric activity as measured by electrogastrography in healthy individuals. The goal was to elucidate the role of central influences in the regulation of normal gastric functioning.

DESIGN

Electrograstrogram (EGG) was recorded during polysomnographically monitored waking and sleep.

SETTING

Sleep laboratory.

PARTICIPANTS

17 healthy volunteers.

MEASUREMENTS AND RESULTS

EGG parameters were computed for 20-minute segments of pre-sleep waking, stage 2 sleep, stage 4 sleep, and REM sleep using both overall and running spectral analysis of EGG data. The dominant power decreased significantly from waking (31.4 +/- 1.4 dB) to all sleep stages (23.1 +/- 1.5 dB during stage 2; 24.7 +/- 1.4 dB during stage 4; 24.3 +/- 1.3 dB during REM sleep). The percentage of 2-4cpm activity decreased significantly during NREM sleep (64.6 +/- 7.6% during stage 2 sleep; 57.5 +/- 5.5% during stage 4 sleep) compared to its waking value (90.8 +/- 3.2%), but not compared to REM sleep (74.1 +/- 5.4%). The instability coefficient of the dominant frequency increased significantly from waking (0.19 +/- 0.03) to all sleep stages (0.36 +/- 0.05 during stage 2 sleep; 0.47 +/- 0.05 during stage 4; 0.34 +/- 0.05 during REM sleep). No significant differences between the sleep stages were found for any measure.

CONCLUSIONS

Sleep is associated with increases in gastric dysrhythmia and instability of the gastric slow wave frequency when compared to waking. These findings suggest that the intrinsic electrical activity of the stomach is significantly influenced by central nervous system mechanisms, and support the notion of a brain-gut axis.

Impaired gastric slow waves induced by spatial disorientation and effect of domperidone

OBJECTIVES

Our aims were to investigate the dominant frequency and regularity of gastric myoelectrical activity during motion sickness induced with the advanced spatial disorientation demonstrator (ASDD) and to evaluate the effect of domperidone on gastric myoelectrical activity and gastrointestinal symptoms during motion sickness.

METHODS

Thirteen healthy volunteers participated in this study. This study was executed using the ASDD, which could duplicate several spatial disorientation phenomena in a safe, controlled environment. Each subject participated in two sessions and received oral administration of 10 mg domperidone before the study in one of the sessions. In each session, three 15-min EGG recordings were made before, during, and after rotation. The symptoms were scored by Graybiel's scale of motion sickness before and after rotation. All EGG data were subjected to computerized spectral analysis to obtain the percentage of normal 2-4 cycles/min (cpm) slow waves, percentage of tachygastria, EGG dominant frequency and power, and instability coefficient of the dominant frequency.

RESULTS

We have found that the percentage of normal gastric slow wave was decreased (control session: 86.2 +/- 4.0% vs 70.0 +/- 5.4%, p < 0.01; domperidone session: 82.7 +/- 4.6% vs 69.8 +/- 5.6%, p < 0.03) and the percentage of tachygastria was increased (control session: 8.7 +/- 3.2% vs 17.8 +/- 5.6%, p < 0.01; domperidone session: 9.2 +/- 3.3% vs 18.1 +/- 3.5%, p < 0.01) after rotation in both sessions. The minute-by-minute variation of the gastric slow wave frequency was significantly increased during rotation in both sessions (control: 0.74 +/- 0.16 vs 1.35 +/- 0.19, p < 0.01; domperidone: 0.90 +/- 0.20 vs 1.47 +/- 0.17, p < 0.01). Domperidone did not prevent dysrhythmia or the symptoms of motion sickness.

CONCLUSIONS

The percentage of normal gastric slow waves is decreased and the percentage of tachygastria is increased with spatial disorientation. Domperidone does not prevent gastric dysrhythmia or the symptoms of motion sickness induced with spatial disorientation.

Postprandial changes of sympathovagal balance measured by heart rate variability

The aim of this study was to investigate the sympathovagal balance after meals by measuring the spectral analysis of heart rate variability (HRV). Nine healthy volunteers were enrolled in this study. The electrocardiogram (ECG) was recorded for 30 min in a fasting state and 60 min after a 500-kcal test meal. The HRV was derived from the ECG and was measured by power spectral analysis using fast-Fourier transform algorithm. It reveals two dominant spectral components. The low-frequency (LF) band reflects primarily sympathetic activity with some parasympathetic input. The high-frequency (HF) band is a reflection of parasympathetic (vagal) activity. The LF-to-HF ratio is considered a marker of sympathovagal balance. It was found that the postprandial LF-to-HF ratio, compared with the fasting state, was significantly increased at both the first 30 min (2.50 +/- 0.49 vs 1.78 +/- 0.33, P < 0.05) and the second 30 min (2.68 +/- 0.55 vs 1.78 +/- 0.33, P < 0.05). The postprandial HF diminished significantly at both the first (16.0 +/- 0.5 vs 21.8 +/- 4.2, P < 0.05) and the second (13.8 +/- 9.5 vs 21.8 +/- 4.2, P < 0.05) 30-min period. In conclusion, the postprandial sympathovagal ratio shows a sustained elevation lasting 1 hr, mainly attributed to diminished vagal activity.

[A reliability growth assessment method and its application in the development of equipment in space cabin]

Objective. To assess and predict reliability of an equipment dynamically by making full use of various test informations in the development of products. Method. A new reliability growth assessment method based on army material system analysis activity (AMSAA) model was developed. The method is composed of the AMSAA model and test data conversion technology. Result. The assessment and prediction results of a space-borne equipment conform to its expectations. Conclusion. It is suggested that this method should be further researched and popularized.

SMRTe, a silencing mediator for retinoid and thyroid hormone receptors-extended isoform that is more related to the nuclear receptor corepressor

SMRT (silencing mediator for retinoid and thyroid hormone receptors) and N-CoR (nuclear receptor copressor) mediate transcriptional repression of important regulators that are involved in many signaling pathways. SMRT and N-CoR are related proteins that form complexes with mSin3A/B and histone deacetylases to induce local chromatin condensation and transcriptional repression. However, SMRT is substantially smaller than N-CoR, lacking an N-terminal domain of approximately 1,000 aa that are present in N-CoR. Here, we report the identification of SMRT-extended (SMRTe), which contains an N-terminal sequence that shows striking similarity with N-CoR. As in N-CoR, this SMRTe-N-terminal domain also represses basal transcription. We find that SMRTe expression is regulated during cell cycle progression and SMRTe transcripts are present in many embryonic tissues. These data redefine a structurally and functionally more related nuclear receptor corepressor family and suggest an additional role for SMRTe in the regulation of cycle-specific gene expression in diverse signaling pathways.

Normalization of atropine-induced postprandial dysrhythmias with gastric pacing

Gastric pacing has received increasing attention recently. However, few studies have systematically assessed the effect of pacing on gastric dysrhythmias. The aims of this study were to investigate the effect of gastric pacing on gastric dysrhythmia and to explore whether the effect of gastric pacing was mediated via cholinergic nerves. Eight hound dogs implanted with three pairs of serosal electrodes were studied. Three study sessions were performed on each dog. The experiment was conducted sequentially as follows: a 30-min myoelectrical recording immediately after a meal, intravenous injection of atropine or saline, and three sequential 20-min myoelectrical recordings with or without gastric pacing during the second 20-min recording. The percentage of regular slow waves (3.5-7. 0 cycles/min) was calculated using spectral analysis. The percentage of the regular slow waves was progressively reduced from 96.7 +/- 1. 7% at baseline to 29.6 +/- 9.0 (P < 0.001), 23.1 +/- 7.1 (P < 0.001), and 27.3 +/- 4.3% (P < 0.001), respectively, during the first, second, and third 20 min after atropine injection. Normalization of the gastric slow wave was achieved with gastric pacing 2.3 +/- 1.0 min after the initiation of pacing. The percentage of regular slow waves was significantly increased both during pacing (93.6 +/- 2.4 vs. 23.1 +/- 7.1%, P < 0.002) and after pacing (70.9 +/- 6.8 vs. 27. 3 +/- 4.3%, P < 0.003) in comparison with the session without pacing. We conclude that 1) atropine induces gastric myoelectric dysrhythmia in the fed state, 2) gastric pacing is able to normalize gastric postprandial dysrhythmia induced by atropine, and 3) the effect of gastric pacing is not mediated by vagal cholinergic mechanism.

Primary intrathoracic malignant fibrous histiocytoma and angiosarcoma

Primary intrathoracic malignant fibrous histiocytoma and angiosarcoma are rare sarcomas constituting less than 0.2% of lung cancers. The typical imaging appearance is a large, well-circumscribed, non-cavitating, non-calcified, peripheral lung mass without hilar or mediastinal lymphadenopathy. Bronchoscopy and percutaneous needle aspiration are of limited value in differential diagnosis, and thoracotomy is warranted for definitive diagnosis.

Blind separation of multichannel electrogastrograms using independent component analysis based on a neural network

The electrogastrogram (EGG) is an abdominal surface measurement of gastric myo-electrical activity which regulates gastric contractions. It is of great clinical importance to record and analyse multichannel EGGs, which provide more information on the propagation and co-ordination of gastric contractions. EGGs are, however, contaminated by myo-electric interference from other organs and artefacts such as motion and respiration. The aim of the study is to separate the gastric signal from noisy multichannel EGGs without any information on the interference, using independent component analysis. A neural-network model is proposed, and corresponding unsupervised learning algorithms are developed to achieve the separation. The performance of the proposed method is investigated using artificial data simulating real EGG signals. Experimental EGG data are obtained from humans and dogs. The processed results of both simulated and real EGG data show the following: first, the proposed method is able to separate normal gastric slow waves from respiratory artefacts and random noises. It is also able to extract gastric slow waves, even when the EGG is contaminated by severe respiratory and ECG artefacts. Secondly, when the stomach contains various gastric electric signals with different frequencies, the proposed method is able to separate these different signals, as illustrated by simulations. These data suggest that the proposed method can be used to separate gastric slow waves, respiratory and motion artefacts, and intestinal myo-electric interference that are mixed in the EGG. It can also be used to detect gastric slow-wave uncoupling, during which the stomach has multiple gastric signals with different frequencies. It is believed that the proposed method may also be applicable to other biomedical signals.

Filter banks and neural network-based feature extraction and automatic classification of electrogastrogram

Dysrhythmia in gastric myoelectrical activity has been frequently observed in patients with gastric motor disorders and gastrointestinal symptoms. The assessment of the regularity of gastric myoelectrical activity is of great clinical significance. The aim of this study was to develop an automated assessment method for the regularity of gastric myoelectrical activity from the surface electrogastrogram (EGG). The method proposed in this paper was based on the filter bank and neural network. First, the EGG signal was divided into frequency subbands using filter bank analysis. Second, a parameter called the subband energy ratio (SER) was computed for each subband signal. A multilayer perceptron neural network was then used to automatically classify the EGG signal into four categories: bradygastria, normal, tachygastria, and arrhythmia, using the SER as the input. The EGG recording was made using the standard method of electrogastrography by placing electrodes on the abdominal surface. The study was performed in 40 patients with various gastric motor disorders, ten healthy adults, and ten healthy children. The neural network was trained and tested using the EGG data obtained from the patients. The regularity of gastric myoelectrical activity was assessed based on the classification of the minute-by-minute EGG segments. Using the running spectral analysis method as a gold standard, the proposed automated method had an accuracy of 100% for the training set and 97% for the test set. It was concluded that the proposed method provides an accurate and automatic assessment of the regularity of gastric myoelectrical activity from the EGG.

Effects of electroacupuncture on gastric migrating myoelectrical complex in dogs

The aim-of this study was to investigate the characteristics of the gastric slow wave during different phases of the migrating myoelectrical complex (MMC) and the effect of electroacupuncture on the MMC. The experiment was performed in eight hound dogs implanted with one pair of bipolar serosal electrodes 2 cm proximal to the pylorus. Gastric myoelectrical activity was recorded for three complete cycles of the MMC in two sessions, one with electroacupuncture at points ST36 and PC6 and the other at sham points. The acupuncture was performed for 30 min in phase I of the second cycle of the MMC. Spectral analysis was performed to compute the frequency and power (amplitude) of the gastric slow wave, whereas blind visual analysis was applied to compute the appearance of spike potentials and the length of each phase of the MMC. It was found that there was a significant difference in the frequency and power of the gastric slow wave during different phases of the MMC (P < 0.05). Phase I was characterized with the highest frequency and lowest power of the gastric slow wave, whereas phase III exhibited the highest power in the slow wave. It was also found that in comparison with the sham points, electroacupuncture at the acupoints increased the number of spike bursts. This increase was not significant during the MMC cycle with electroacupuncture (34.4+/-4.1 vs 27.5+/-2.5%, P > 0.05) but became significant during the cycle after electroacupuncture (39.8+/-3.3% vs 27.5+/-2.5%, P < 0.0005). Similarly, during the MMC cycle after electroacupuncture at the acupoints, there was a significant decrease in the length of phase I (14.8+/-2.2 vs 46.9+/-6.1 min, P < 0.003) and a significant increase in the length of phase II (75.6+/-9.9 vs 30.6+/-4.1 min, P < 0.003) and phase III (25.8+/-0.6 vs 22.1+/-0.7 min, P < 0.003). A similar increase was observed during the MMC cycle with electroacupuncture but was not statistically significant. In conclusion, the gastric slow wave has the highest power during phase III of the MMC, indicating that the antral contraction is characterized not only by the appearance of spikes, but also by the increased power of the slow wave. Electroacupuncture at acupoints of ST36 and PC6 enhances the gastric MMC by reducing the length of phase I and increasing the length of phases II and III.

Gastric myoelectrical activity in patients with cervical spinal cord injury

OBJECTIVE

Dyspeptic symptoms are common in patients with cervical spinal cord injury (SCI). The supraspinal control of sympathetic innervation to the stomach is interrupted in these patients. Gastric emptying has been reported to be delayed in some patients with cervical SCI. Gastric myoelectrical activity is known to regulate gastric motility and is correlated with gastric emptying. The change in gastric myoelectrical activity after cervical SCI is unknown; our aim was to investigate it.

METHODS

The study was performed in 12 cervical SCI patients and 14 healthy controls. Gastric myoelectrical activity was recorded using surface electrogastrography for 30 min in the fasting state and 1 h after a standard test meal. Spectral analysis was performed to compute the following parameters from the electrogastrogram; investigated were the percentage of 2-4 cycles/min (cpm) slow waves, the instability coefficient (IC) of the dominant frequency, the postprandial increment of dominant frequency (deltaF), and its power (deltaP).

RESULTS

In both fasting and fed states, regular and stable gastric slow waves were observed in both the control group and patients with cervical SCI. The percentage of normal 2-4 cpm slow waves (preprandial, 80.7+/-3.6% vs 91.5+/-3.7%, p > 0.05; postprandial, 82.0+/-4.4% vs 87.2+/-4.2%, p > 0.05) and IC (preprandial, 0.19+/-0.04% vs 0.28+/-0.05%; postprandial, 0.24+/-0.04% vs 0.27+/-0.02%, p > 0.05) were not significantly different between the two groups. The dominant frequency and its power were also similar between the two groups, no matter whether in the fast (frequency, 2.92+/-0.3 vs 2.93+/-0.06 cpm; power, 30.05+/-1.29 vs 29.08+/-1.23 dB, p > 0.05) or fed (frequency, 3.17+/-0.07 vs 3.02+/-0.06 cpm; power, 32.55+/-0.90 vs 32.07+/-1.18 dB,p > 0.05) state. The postprandial response measured by deltaF (0.25+/-0.09 vs 0.09+/-0.07 cpm, p > 0.05) and deltaP (2.52+/-1.10 vs 2.24+/-1.20 dB, p > 0.05) were also similar between the two groups.

CONCLUSION

Gastric myoelectrical activity was not altered after cervical SCI.

Gastric myoelectrical activity in healthy children and children with functional dyspepsia

The aim of this study was to investigate abnormalities in pediatric patients with functional dyspepsia. Fifteen symptomatic pediatric patients diagnosed with functional dyspepsia and 17 aged-matched healthy controls were studied. Gastric myoelectrical activity was recorded using surface electrogastrography for 1 hr in the fasting state and 1 hr after a test meal. It was found that, in comparison with the controls, the children with functional dyspepsia had a lower percentage of 2- to 4-cpm slow waves in both fasting state (66.0+/-4.7% vs 79.7+/-3.1%, P < 0.07) and fed state (72.4+/-5.4% vs 85.0+/-2.9%, P < 0.04), and a significantly higher instability of the dominant frequency in both fasting state (0.50+/-0.05 vs 0.31+/-0.04, P < 0.01) and fed state (0.39+/-0.05 vs 0.25+/-0.03, P < 0.05). It was also found the postprandial increase in EGG dominant power in the patients was inversely correlated with the total symptom score (r = 0.63, P = 0.03). It was concluded that abnormal gastric myoelectrical activity may play a role in the pathogenesis of pediatric functional dyspepsia.

Optimized overcomplete signal representation and its applications to time-frequency analysis of electrogastrogram

The electrogastrogram (EGG) is a surface measurement of gastric myoelectrical activity. The normal frequency of gastric myoelectrical activity in humans is 3 cycles/min. Abnormal frequencies in gastric myoelectrical activity have been found to be associated with functional disorders of the stomach. The aim of this article was, therefore, to develop new time-frequency analysis methods for the detection of gastric dysrhythmia from the EGG. A concept of overcomplete signal representation was used. Two algorithms were proposed for the optimization of the overcomplete signal representation. One was a fast algorithm of matching pursuit and the other was based on an evolutionary program. Computer simulations were performed to compare the performance of the proposed methods in comparison with existing time-frequency analysis methods. It was found that the proposed algorithms provide higher frequency resolution than the short time Fourier transform and Wigner-Ville distribution methods. The practical application of the developed methods to the EGG is also presented. It was concluded that these methods are well suited for the time-frequency analysis of the EGG and may also be applicable to the time-frequency analysis of other biomedical signals.