Myoelectric Activity Research Articles

Selective stimulation of the ferret abdominal vagus nerve with multi-contact nerve cuff electrodes

Dysfunction and diseases of the gastrointestinal (GI) tract are a major driver of medical care. The vagus nerve innervates and controls multiple organs of the GI tract and vagus nerve stimulation (VNS) could provide a means for affecting GI function and treating disease. However, the vagus nerve also innervates many other organs throughout the body, and off-target effects of VNS could cause major side effects such as changes in blood pressure. In this study, we aimed to achieve selective stimulation of populations of vagal afferents using a multi-contact cuff electrode wrapped around the abdominal trunks of the vagus nerve. Four-contact nerve cuff electrodes were implanted around the dorsal (N = 3) or ventral (N = 3) abdominal vagus nerve in six ferrets, and the response to stimulation was measured via a 32-channel microelectrode array (MEA) inserted into the left or right nodose ganglion. Selectivity was characterized by the ability to evoke responses in MEA channels through one bipolar pair of cuff contacts but not through the other bipolar pair. We demonstrated that it was possible to selectively activate subpopulations of vagal neurons using abdominal VNS. Additionally, we quantified the conduction velocity of evoked responses to determine what types of nerve fibers (i.e., Aδ vs. C) responded to stimulation. We also quantified the spatial organization of evoked responses in the nodose MEA to determine if there is somatotopic organization of the neurons in that ganglion. Finally, we demonstrated in a separate set of three ferrets that stimulation of the abdominal vagus via a four-contact cuff could selectively alter gastric myoelectric activity, suggesting that abdominal VNS can potentially be used to control GI function.

Effect of hand loads on upper extremity muscle activity during pushing and pulling motions

Manual pushing or pulling with a hand tool is a coordinated action by various upper extremity muscles. The objective of this experimental study was to examine the effects of horizontal and vertical hand loads on upper extremity muscle activity during concentric pushing and pulling exertions. Twenty young female participants conducted repetitive pushing and pulling trials with three horizontal loads (1 kg, 2 kg, 3 kg) and two vertical loads (0.6 kg, 1.3 kg) in a seated posture, while the myoelectric activity of seven upper extremity and shoulder muscles were quantified. Study results indicate that the shoulder flexor and extensor muscles were more strongly associated with horizontal load, and elbow flexors were more sensitive to vertical load. The empirical data from this systematic evaluation can offer initial insights for ergonomic design and evaluation of hand tools or occupational tasks that involve repetitive pushing or pulling.

Dextran Sodium Sulphate-Induced Gastrointestinal Injury Further Aggravates the Impact of Galantamine on the Gastric Myoelectric Activity in Experimental Pigs

Galantamine has been used as a treatment for Alzheimer disease. It has a unique, dual mode of action (inhibitor of acetylcholinesterase and allosteric modulator of nicotinic acetylcholine receptors). Nausea (in about 20%), vomiting (10%) and diarrhoea (5–7%) are the most common side effects. The aim of this study was to assess the effect of galantamine on porcine gastric myoelectric activity without (Group A) and with (Group B) dextran sodium sulphate (DSS)-induced gastrointestinal injury. Galantamine hydrobromide was administrated to twelve pigs as a single intragastric dose (24 mg). Gastric myoelectric activity was investigated by electrogastrography (EGG). Basal (15 min before galantamine administration) and study recordings after galantamine administration (300 min) were evaluated using a running spectral analysis. Results were expressed as dominant frequency of gastric slow waves and power analysis (areas of amplitudes). Altogether, 3780 one-minute EGG recordings were evaluated. In Group A, power was steady from basal values for 180 min, then gradually decreased till 270 min (p = 0.007). In Group B, there was a rapid gradual fall from basal values to those after 120 min (p = 0.007) till 300 min (p ˂ 0.001). In conclusion, galantamine alone revealed an unfavourable effect on porcine myoelectric activity assessed by gastric power. It can be a plausible explanation of galantamine-associated dyspepsia in humans. DSS caused further profound decrease of EGG power. That may indicate that underlying inflammatory, ischaemic or NSAIDs-induced condition of the intestine in humans can have aggravated the effect of galantamine on gastric myoelectric activity.

Different plantar flexors neuromuscular and mechanical characteristics depending on the preferred running form

Two main types of endurance runners have been identified: aerial runners (AER), who have a larger flight time, and terrestrial runners (TER), who have a longer ground contact time. The purpose of this study was to assess the neuromuscular characteristics of plantar flexors between AER and TER runners. Twenty-four well-trained runners participated in the experiment. They were classified either in a TER or AER group according to the Volodalen® scale. Plantar flexors’ maximal rate of force development (RFD) and maximal voluntary contraction force (MVC) were assessed. Percutaneous electrical stimulation was delivered to the posterior tibial nerve to evoke maximal M-waves and H-reflexes of the triceps surae muscles. These responses, as well as voluntary activation, muscle potentiation, and V-waves, were recorded by superimposing stimulations to MVCs. RFD was significantly higher in AER than in TER, while MVC remained unchanged. This was accompanied by higher myoelectrical activity recorded in the soleus muscle. While M-waves and other parameters remained unchanged, maximal H-reflex was significantly higher in AER than in TER, still in soleus only. The present study raised the possibility of different plantar flexors’ neuromuscular characteristics according to running profile. These differences seemed to be focused on the soleus rather than on the gastrocnemii.

New Insights About the Sticking Region in Back Squats: An Analysis of Kinematics, Kinetics, and Myoelectric Activity.

The aim of this study was to investigate barbell, joint kinematics, joint kinetics of hip, knee, and ankle in tandem with myoelectric activity around the sticking region in three-repetition maximum (3-RM) back squats among recreationally trained lifters. Unlike previous literature, this study also investigated the event of first-peak deacceleration, which was expected to be the event with the lowest force output. Twenty-five recreationally trained lifters (body mass: 70.8 ± 10.5, age: 24.6 ± 3.4, height: 172 ± 8.5) were tested in 3-RM back squats. A repeated one-way analysis of variance showed that ground reaction force output decreased at first peak deacceleration compared with the other events. Moreover, torso forward lean, hip moment arm, and hip contribution to total moment increased, whereas the knee moment arms and moment contribution to total moment decreased in the sticking region. Also, stable moment arms and moment contributions to total moment were observed for the ankle in the sticking region. Furthermore, the knee extensors together with the soleus muscle decreased myoelectric activity in the post-sticking region, while the gluteus maximus and biceps femoris increased myoelectric activity in the post-sticking region. Our findings suggest that the large hip moment arms and hip contributions to total moment together with a lower myoelectric activity for the hip extensors contribute to a poor biomechanical region for force output and, thereby, to the sticking region among recreationally trained lifters in 3-RM back squats.

Low-Load Blood-Flow Restriction Exercise to Failure and Nonfailure and Myoelectric Activity: A Meta-Analysis.

To compare the short- and long-term effects of low-load resistance training with blood-flow restriction (LL-BFR) versus low- (LL-RT) or high- (HL-RT) load resistance training with free blood flow on myoelectric activity and investigate the differences between failure (exercise performed to volitional failure) and nonfailure (exercise not performed to volitional failure) protocols. We identified sources by searching the MEDLINE, PubMed, CINAHL, Web of Science, CENTRAL, Scopus, SPORTDiscus, and PEDro electronic databases. We screened the titles and abstracts of 1048 articles using our inclusion criteria. A total of 39 articles were selected for further analysis. Two reviewers independently assessed the methodologic quality of each study and extracted the data. A meta-analytic approach was used to compute standardized mean differences (SMDs) ± 95% CIs. Subgroup analyses were conducted for both failure and nonfailure protocols. The search identified 39 articles that met the inclusion criteria. Regarding the short-term effects, LL-BFR increased muscle excitability compared with LL-RT during nonfailure protocols (SMD = 0.61; 95% CI = 0.34, 0.88), whereas HL-RT increased muscle excitability compared with LL-BFR during failure (SMD = -0.61; 95% CI = -1.01, -0.21) and nonfailure (SMD = -1.13; 95% CI = -1.94, -0.33) protocols. Concerning the long-term effects, LL-BFR increased muscle excitability compared with LL-RT during exercises performed to failure (SMD = 1.09; 95% CI = 0.39, 1.79). Greater short-term muscle excitability levels were observed in LL-BFR than in LL-RT during nonfailure protocols. Conversely, greater muscle excitability was present during HL-RT than LL-BFR, regardless of volitional failure. Furthermore, LL-BFR performed to failure increased muscle excitability in the long term compared with LL-RT.

Role of antispasmodics in the treatment of irritable bowel syndrome

Introduction. IBS is a functional bowel disorder that has a significant impact on patients and society, especially in terms of quality of life and medical costs.Pathogenesis. It is believed that the pathogenesis of IBS consists of several mechanisms: the syndrome of intersection of functional disorders (gut-brain), stress, visceral hypersensitivity and changes in motor skills.Visceral hypersensitivity. Changes in visceral sensitivity in IBS are characterized by central abnormalities in areas of the cerebral cortex. Motility impairment in IBS manifests itself as abnormal myoelectric activity in the colon, resulting in repetitive contractions of the small intestine and colon, which appear to cause pain.Intestinal microflora. FODMAPs are found in high amounts in some fruits, artificial sweeteners, legumes, and green vegetables and are poorly absorbed by all people. FODMAPs have enzymatic and osmotic effects that may contribute to the onset of symptoms in some patients.The principles of IBS therapy. Treatment for IBS should be based on the type and severity of symptoms. For the treatment of IBS, drugs of various pharmacological groups are used, depending on the prevailing symptoms. These include opioid receptor agonists, bile acid sequestrants, guanylate cyclase agonists, chlorine channel activators, as well as antibiotics, probiotics, antidepressants, 5-HT3 receptor antagonists, and antispasmodics.Myotropic antispasmodics. Drugs with antispasmodic activity are used to treat functional and organic diseases of the gastrointestinal tract as a basic therapy or «on demand». Mebeverine quickly and effectively relieves spasm, pain and the entire complex of intestinal symptoms, in addition, the drug reduces visceral hypersensitivity due to a local anesthetic effect. The drug has a high safety profile and has a number of advantages over drugs of the same pharmacological group.Conclusion. Myotropic antispasmodics have been shown to be highly effective in the treatment of IBS. Mebeverine occupies a special place among myotropic antispasmodics. Its combined action provides a pronounced antispasmodic activity along with a high safety profile.

Fatigue induces altered spatial myoelectric activation patterns in the medial gastrocnemius during locomotion.

This research investigates the effects of muscle fatigue on spatial myoelectric patterns in the lower limb during locomotion. Both spatial and frequency aspects of neuromuscular recruitment in the medial gastrocnemius change in response to fatigue, resulting in altered myoelectric patterns during walking and running. These data may help us better understand the adaptations that occur in lower limb muscles to avoid overuse injuries caused by fatigue.

Principal postural acceleration and myoelectric activity: Interrelationship and relevance for characterizing neuromuscular function in postural control

One approach to investigating sensorimotor control is to assess the accelerations that produce changes in the kinematic state of the system. When assessing complex whole-body movements, structuring the multi-segmental accelerations is important. A useful structuring can be achieved through a principal component analysis (PCA) performed on segment positions followed by double-differentiation to obtain "principal accelerations" (PAs). In past research PAs have proven sensitive to altered motor control strategies, however, the interrelationship between PAs and muscle activation (surface electromyography, sEMG) have never been determined. The purpose of the current study was therefore to assess the relationship between PAs and sEMG signals recorded from muscles controlling the ankle joint during one-leg standing trials. It was hypothesized that medium correlation should be observed when accounting for neurophysiologic latencies (electro-mechanical delay). Unipedal balancing on a level-rigid ground was performed by 25 volunteers. sEMG activities were recorded from the tibialis anterior, peroneus longus, gastrocnemius medialis, and soleus muscles of the stance leg. The first eight PA-time series were determined from kinematic marker data. Then, a cross-correlation analysis was performed between sEMG and PA time series. We found that peak correlation coefficients for many participants aligned at time delays between 0.116 and 0.362s and were typically in the range small to medium (|r| = 0.1 to 0.6). Thus, the current study confirmed a direct association between many principal accelerations PA(t) and muscle activation signals recorded from four muscles crossing the ankle joint complex. The combined analysis of PA and sEMG signals allowed exploring the neuromuscular function of each muscle in different postural movement components.

The Impact of Dextran Sodium Sulfate-Induced Gastrointestinal Injury on the Pharmacokinetic Parameters of Donepezil and Its Active Metabolite 6-O-desmethyldonepezil, and Gastric Myoelectric Activity in Experimental Pigs.

Gastrointestinal side effects of donepezil, including dyspepsia, nausea, vomiting or diarrhea, occur in 20–30% of patients. The pathogenesis of these dysmotility associated disorders has not been fully clarified yet. Pharmacokinetic parameters of donepezil and its active metabolite 6-O-desmethyldonepezil were investigated in experimental pigs with and without small intestinal injury induced by dextran sodium sulfate (DSS). Morphological features of this injury were evaluated by a video capsule endoscopy. The effect of a single and repeated doses of donepezil on gastric myoelectric activity was assessed. Both DSS-induced small intestinal injury and prolonged small intestinal transit time caused higher plasma concentrations of donepezil in experimental pigs. This has an important implication for clinical practice in humans, with a need to reduce doses of the drug if an underlying gastrointestinal disease is present. Donepezil had an undesirable impact on porcine myoelectric activity. This effect was further aggravated by DSS-induced small intestinal injury. These findings can explain donepezil-associated dyspepsia in humans.

Long-Term Recording of Reticulo-Rumen Myoelectrical Activity in Sheep by a Telemetry Method.

Simple SummaryThe motility of the smooth muscle of the rumen and the reticulum is tightly synchronized since they are responsible for degrading the ingested fibrous diet. It involves mixing contractions of partially digested material (cycle A), cyclic eructation of fermented gases (cycle B), and contractions associated with regurgitation and rumination (cycle C). Disorders of cycles A, B, and C in reticulo-rumen contraction occurred in cases of many metabolic diseases. Since the smooth muscle electromyography (EMG) is closely associated with the motility pattern, our study aimed to implement the long-term EMG telemetry recording method to analyze the basic reticulo-rumen motility pattern in conscious unrestrained sheep. The study was conducted on nine ewes chronically fitted with bipolar electrodes in the rumen and reticulum. Cycles A and B occurred constantly in a similar share, whereas cycles C appeared every 30 min and lasted for the most part 15–30 min. EMG signal analysis showed more differences at the level of single bursts than on burst bundles. Recording reticulo-rumen EMG signal with a long-term telemetry approach offers a reliable tool to assess the forestomach motility in conscious, unrestrained sheep, allowing for easy recognition of reticulo-rumen cycles.The reticulum and rumen are considered a single functional unit (the reticulo-rumen) with regards to myoelectrical and contractile activities. The specialized contractions of the reticulo-rumen provide constant mixing of partially digested material (cycle A), its flow into the omasum during eructation (cycle B), and regurgitation-rumination (cycle C). This study aimed to investigate the feasibility of electromyography (EMG) registered by a long-term telemetry method for assessment of the basic reticulo-rumen myoelectrical activity in sheep, to develop the effective recognition of the reticulo-rumen cycles at rest with no food stimulation, and to investigate the relationship between cycles A, B, and C in such basic conditions. The experiment was carried out on nine ewes. Myoelectric activity of the rumen, reticulum, and abomasum was recorded by the combination of three silver bipolar electrodes and a 3-channel transmitter implant. The myoelectrical activity registered successfully in the reticulum and rumen was determined as three characteristic patterns of cycles A, B, and C. The percentage of each type of cycle changed at different intervals from equally cycles A (43–50%) and B (50–56%), occurring when cycle C was not observed to the domination of cycle C (57–73%) with a decrease of cycles A (6–14%) and B (20–28%). The long-term EMG telemetry registration is feasible in the assessment of the reticulo-rumen myoelectrical activity in sheep.

Functional and morphological comparison of extracellular matrices derived from porcine small intestinal submucosa and porcine dermis to support rabbit uterus regeneration.

he aim of this study was to compare the ability of extracellular matrices (ECMs) of various structural origins to support uterus regeneration and maintain contractile function. The experiment was carried out in 18 New Zealand white female rabbits divided into a control group and two experimental groups. In the control group, bipolar electrodes were attached to the uterine horns to collect electromyography data. In the experimental groups, uterine horns were partially excised with immediate implantation of the extracellular matrix (ECM) derived from porcine small intestinal submucosa (SIS), DynaMatrix®, or from porcine dermis, Medeor® Matrix. Twelve weeks later, bipolar electrodes were attached to the regeneration areas in both experimental groups. The electromyography data in all groups were continuously recorded after administration of a single dose of estradiol valerate. Fourteen weeks after EMCs implantation, the rabbits were spayed, and the uterine wall was sampled for histological and immunohistochemical evaluation. The regenerated uterus retained the myoelectric activity pattern, and the mean amplitudes of maximum deflections did not differ between the experimental and control groups. The regeneration supported by the SIS-derived ECM was more advanced than that supported by the dermal-derived ECM. However, some pathological changes were noted in both experimental groups within the regeneration areas.

Factors associated with electrical stimulation-induced performance fatigability are dependent upon stimulation location.

What is the central question of this study? How does peripheral nerve stimulation (PNS) compare with neuromuscular electrical stimulation (NMES) used clinically to reduce muscle atrophy? What is the main finding and its importance? NMES resulted in progressive increases in M-wave duration and delay of muscle relaxation throughout a single stimulation protocol, findings not observed with PNS. This suggests PNS recruits from a wider pool of muscle fibres/motor units, providing a more favourable alternative to NMES for rehabilitation intervention. Neuromuscular electrical stimulation (NMES) is increasingly viewed as a central tenet to minimise muscle loss during periods of disuse/illness - typically applied directly over a muscle belly. Peripheral nerve stimulation (PNS) is afforded less attention, despite providing a more global contractile stimulus to muscles. We investigated NMES versus PNS in relation to performance fatigability and peripheral contributions to voluntary force capacity. Two fatigue protocols were assessed separately: (1) over-quadriceps NMES and (2) peripheral (femoral) nerve stimulation (PNS). Before and after each session, a maximal voluntary contraction (MVC) was performed to assess force loss. Knee-extensor force was measured throughout to assess contractile function in response to submaximal electrical stimulation, and M-wave features quantified myoelectrical activity. NMES and PNS induced similar voluntary (MVC, NMES: -12±9%, PNS: -10±8%, both P<0.001) and stimulated (NMES: -45±12%, PNS -27±27%, both P<0.001) force reductions. Although distinct between protocols, myoelectrical indicators of muscle recruitment (M-wave area and amplitude) and nerve conduction time did not change throughout either protocol. Myoelectrical propagation speed, represented as M-wave duration, and the delay before muscle relaxation began both progressively increased during NMES only (P<0.05 and P<0.001, respectively). NMES myoelectrical changes suggested performance fatigability, indicating activation of superficial fibres only, which was not observed with PNS. This suggests PNS recruits a wider pool of muscle fibres and motor units and is a favourable alternative for rehabilitation. Future work should focus on implementing PNS interventions in clinically relevant scenarios such as immobilisation, care homes and critical illness.

The Mysterious Island: Insula and Its Dual Function in Sleep and Wakefulness.

In the recent sleep studies, it was shown that afferentation of many cortical areas switches during sleep to the interoceptive one. However, it was unclear whether the insular cortex, which is often considered as the main cortical visceral representation, maintains the same effective connectivity in both states of vigilance, or processes interoceptive information predominantly in one state. We investigated neuronal responses of the cat insular cortex to electrical stimulations of the intestinal wall delivered during wakefulness and natural sleep. Marked increase was observed in the number of insular neurons responding to this stimulation in sleep comparing to wakefulness, and enlarged amplitudes of evoked local field potentials were found as well. Moreover, most of the cells responding to intestinal stimulation in wakefulness never responded to identical stimuli during sleep and vice versa. It was also shown that applied low intensity intestinal stimulations had never compromised sleep quality. In addition, experiments with microstimulation of the insular cortex and recording of intestinal myoelectric activity demonstrated that effective insula-to-gut propagation also happened only during sleep. On the other hand, the same insular stimulations in wakefulness led to contractions of orofacial muscles. The evoked face movements gradually disappeared in the course of sleep development. These findings demonstrate that pattern of efficient afferent and efferent connections of the insular cortex changes with transition from wakefulness to sleep.

A potential upper motor neuron measure of bulbar involvement in amyotrophic lateral sclerosis using jaw muscle coherence

Objective To identify a novel, quantitative bulbar measure in amyotrophic lateral sclerosis (ALS) based on jaw muscle coherence. Methods: The myoelectric activities of masseter, anterior temporalis, and anterior belly of digastric were recorded bilaterally during a speech task in 12 individuals with ALS and 10 neurologically healthy controls, using surface electromyography. Coherence and directed coherence were calculated for all muscle pairs. The muscle pairs showing significant coherence and directed coherence in the beta-band (15–35 Hz) were identified and their mean beta-band coherence were (1) correlated with the kinematic (i.e. jaw acceleration time) and functional speech (i.e. speaking rate) measures that have been previously identified to be affected by bulbar ALS, across all participants, and (2) evaluated in terms of their efficacy in differentiating individuals with ALS from healthy controls. Results: Beta-band coherence was in general reduced in ALS relative to healthy controls, with the antagonistic and homologous muscle pairs being more affected than the agonistic pairs. Among all muscle pairs, the coherence between masseter and digastric (1) showed the strongest correlations with jaw acceleration time and speaking rate, and (2) differentiated individuals with ALS from healthy controls with the highest sensitivity (i.e. 0.92) and specificity (i.e. 0.90). Conclusions: Reduced beta-band coherence between masseter and digastric in ALS reflects weakened neural linkage between these muscles resulting from the disrupted cortical drive to the bulbar musculature. These findings provide preliminary evidence for jaw muscle coherence as a novel, quantitative measure of corticobulbar involvement, designed to improve bulbar assessment in ALS.

Electrogastrography in Autonomous Vehicles-An Objective Method for Assessment of Motion Sickness in Simulated Driving Environments.

Autonomous vehicles are expected to take complete control of the driving process, enabling the former drivers to act as passengers only. This could lead to increased sickness as they can be engaged in tasks other than driving. Adopting different sickness mitigation techniques gives us unique types of motion sickness in autonomous vehicles to be studied. In this paper, we report on a study where we explored the possibilities of assessing motion sickness with electrogastrography (EGG), a non-invasive method used to measure the myoelectric activity of the stomach, and its potential usage in autonomous vehicles (AVs). The study was conducted in a high-fidelity driving simulator with a virtual reality (VR) headset. There separate EGG measurements were performed: before, during and after the driving AV simulation video in VR. During the driving, the participants encountered two driving environments: a straight and less dynamic highway road and a highly dynamic and curvy countryside road. The EGG signal was recorded with a proprietary 3-channel recording device and Ag/AgCl cutaneous electrodes. In addition, participants were asked to signalize whenever they felt uncomfortable and nauseated by pressing a special button. After the drive they completed also the Simulator Sickness Questionnaire (SSQ) and reported on their overall subjective perception of sickness symptoms. The EGG results showed a significant increase of the dominant frequency (DF) and the percentage of the high power spectrum density (FSD) as well as a significant decrease of the power spectrum density Crest factor (CF) during the AV simulation. The vast majority of participants reported nausea during more dynamic conditions, accompanied by an increase in the amplitude and the RMS value of EGG. Reported nausea occurred simultaneously with the increase in EGG amplitude. Based on the results, we conclude that EGG could be used for assessment of motion sickness in autonomous vehicles. DF, CF and FSD can be used as overall sickness indicators, while the relative increase in amplitude of EGG signal and duration of that increase can be used as short-term sickness indicators where the driving environment may affect the driver.

Autonomic and enteric function profiling can predict disordered gastric emptying in diabetic gastropathy.

Gastric emptying tests (GET) are the gold standard for diagnosing gastroparesis, but many patients do not have delayed emptying. We aimed to examine the combination of autonomic nervous system testing (ANS) and the enteric measure (ENS) of electrogastrography (EGG) to predict disordered GET. Seventy-six patients (47 F, 29 M mean age 40 years) with diabetes mellitus underwent evaluation for end-organ failure including gastroparesis. ANS testing assessed autonomic function by finger capillary pulse to positional changes (PAR), vasoconstriction to cold (VC), and EKG R-R interval change (RRI) with deep breathing; the ENS measures of cutaneous EGG assessed gastric myoelectrical activity. Solid (S) GET subgroups were based on 50% emptying (TS50). Via linear regression analysis: VC, PAR, and EGG had a significant inverse correlation with GET TS50 and decreased in response to a delay in gastric emptying (p < 0.05). Via ordinal logistic regression RRI and EGG-predicted gastric emptying (p < 0.01). Patients with a higher RRI and EGG value were 0.93 and 0.14 times more likely to be diagnosed with rapid gastric emptying. The areas under the curve for receiver operator characteristics (AUROC) for all measures were 0.72 in comparison to 0.59 with EGG. Based on the results, four components (RRI, VC, PAR, and EGG) quantitatively describe gastric emptying in patients with signs of diabetic gastropathy better than EGG alone.

Sulprostone-Induced Gastric Dysrhythmia in the Ferret: Conventional and Advanced Analytical Approaches.

Nausea and emesis resulting from disease or drug treatment may be associated with disrupted gastric myoelectric activity (GMA). Conventional analytical techniques can determine the relative degrees of brady-, normo-, and tachygastric power, but lose information relative to the basic slow wave shape. The aim of the present study was to investigate the application of advanced analytical techniques in the analysis of disrupted GMA recorded after administration of sulprostone, a prostaglandin E3/1 agonist, in ferrets. Ferrets were implanted with radiotelemetry devices to record GMA, blood pressure, heart rate (HR) and core body temperature 1 week before the administration of sulprostone (30 μg/kg) or vehicle (saline, 0.5 mL/kg). GMA was initially analyzed using fast Fourier transformations (FFTs) and a conventional power partitioning. Detrended fluctuation analysis (DFA) was also applied to the GMA recordings to reveal information relative to the fluctuation of signals around local trends. Sample entropy (SampEn) analysis was used for examining the regularity of signals. Conventional signal processing techniques revealed that sulprostone increased the dominant frequency (DF) of slow waves, with an increase in the percentage power of the tachygastric range and a decrease in the percentage power of the normogastric range. DFA revealed that sulprostone decreased the fluctuation function, indicative of a loss of the variability of GMA fluctuations around local trends. Sulprostone increased SampEn values, indicating a loss of regularity in the GMA data. Behaviorally, sulprostone induced emesis and caused defecation. It also increased blood pressure and elevated HR, with an associated decrease in HR variability (HRV). Further analysis of HRV revealed a decrease in both low-frequency (LF) and high-frequency (HF) components, with an overall increase in the LF/HF ratio. Sulprostone did not affect core body temperature. In conclusion, DFA and SampEn permit a detailed analysis of GMA, which is necessary to understand the action of sulprostone to modulate gastric function. The action to decrease HRV and increase the LF/HF ratio may be consistent with a shift toward sympathetic nervous system dominance, commonly seen during nausea.

Resistance of postprandial gastric functions and autonomic balance to taste stimulation.

Exposure to unpleasant tastes leads to disturbances of interdigestive gastric myoelectrical activity (GMA) and may affect sympathetic/parasympathetic balance (SPB). We made a careful study to determine whether taste stimulation modulates the postprandial GMA, SPB, and gastric emptying (GE) of a solid meal. Eighteen healthy volunteers (9F/9M) entered the study. On six separate days, we recorded a four-channel electrogastrogram from each volunteer during a 35-min fasting period, then for 90 min after ingestion of a solid test meal of 300 kcal. GE was measured using a 13C-octanoic acid breath test. Heart rate variability (HRV) analysis was simultaneously performed. At the start of the 21st min after the test meal, subjects received an agar cube delivering either a sweet, salty, sour, or bitter taste, which they kept in the mouth for 35 min. Control procedures involved sessions performed with a tasteless agar cube, and without any stimulation. There was no effect of the experimental intervention upon the relative power share of particular GMA rhythms. Stimulation with the salty and the bitter taste evoked a statistically significant increase in the dominant frequency, whereas the sweet and sour taste did not affect it. Taste stimulation did not interfere with the meal-induced rise in the dominant power, nor affect slow wave coupling. The kinetics of the solid GE remained unchanged by the intervention. None of the taste stimulations affected the postprandial SPB. Taste stimulation elicited after ingestion of a meal, in contrast to that during a fast, did not adversely modify the postprandial pattern of either the GMA or SPB, nor affect the GE of solids.

The effect of visceral reception activation (water load test) on autonomic activity and gastric myoelectric activity in gastrointestinal malignancies.

The aim of this study was to analyze the effect of water load test (WLT) on heart rate variability (HRV), blood pressure variability (BPV), hemodynamic parameters and gastric myoelectric activity in gastrointestinal (GI) cancer patients. WLT activates gastrointestinal mechanoreception and osmoreception, and hence, can indirectly modulate autonomic activity. Eighty patients (mean age 61.2 years) were enrolled, along with the group of healthy controls. HRV, BPV and electrogastrography (EGG) were recorded at rest (in a fasted state) and after water uptake at 100 ml/min. WLT contributed to an increase in the percentages of normogastria time, from 37.3 % to 50.0 % (p=0.02) and from 42.3 % to 47.7 % (p=0.01), respectively in colon and rectal cancer. Cancer patients presented lower values of HRV indices determined on linear analysis at rest and after WLT. A slight predominance of the sympathetic component was observed in response to WLT, which was reflected by changes in hemodynamic parameters. The response to WLT is a consequence of GI mechanoreception and osmoreception activation and resultant pressure reaction. This effect was disrupted by the neoplastic process within the GI tract, especially in gastric and colon malignancies, but not in rectal cancer (Tab. 2, Fig. 12, Ref. 40). Text in PDF www.elis.sk Keywords: autonomic nervous system, gastric myoelectric activity, water uptake, heart rate variability, blood pressure variability, gastrointestinal cancer.