Antral Contractions Research Articles

Gastric-filling ultrasonography to evaluate gastric motility in patients with Parkinson's disease.

Delayed gastric emptying is a common non-motor symptom of Parkinson's disease (PD). However, there is currently no objective evaluation and diagnostic method for this condition. The purpose of this study was to evaluate the feasibility of gastric-filling ultrasonography for gastric motility in patients with PD and the relationship between gastric dynamics and gastrointestinal symptoms and motor symptoms of PD. We performed a case-control study with 38 patients with PD and 34 healthy controls. All patients underwent a 120-min ultrasonography examination using a 500-ml semi-liquid test meal. We determined the antral contraction amplitude (ACA), the antrum contraction frequency (ACF), the motility index (MI), and the gastric antral cross-sectional area (CSA). We acquired the CSA at six time points: fasting for 12 h (T0), immediately after drinking the semi-liquid test meal (T1); and at 30 (T30), 60 (T60), 90 (T90), and 120 (T120) min. We calculated the gastric emptying rate (GER) at different time points by using the CSA. We compared the GER between the groups and evaluated the correlation between the GER and gastrointestinal symptoms and motor symptoms of PD. The MI and ACF were significantly lower in the PD group compared with the control group (P < 0.05). The GER at T30 and the ACA showed no significant difference between the groups (P > 0.05). At different time points, the GER was significantly different between the PD and control groups (P < 0.001). There was no significant association between the GER and gastrointestinal symptoms; none of them were risk factors for impaired gastric emptying (odds ratio > 1). The GER was negatively correlated with the severity of PD motor symptoms (P < 0.05). Patients with PD had significantly delayed gastric emptying, which was negatively correlated with the severity of PD motor symptoms. Measuring gastric emptying by gastric-filling ultrasound had good diagnostic value in clinical screening for delayed gastric motility in patients with PD. https://www.chictr.org.cn/showproj.html?proj=126304.

Biomimetic Closed-Loop Control of a Novel Soft Gastric Simulator Toward Emulating Antral Contraction Waves.

Soft gastric simulators are in vitro biomimetic modules that can reproduce the antral contraction waves (ACWs). Along with providing information concerning stomach contents, stomach simulators enable experts to evaluate the digestion process of foods and drugs. Traditionally, open-loop control approaches were implemented on stomach simulators to produce ACWs. Constructing a closed-loop control system is essential to improve the simulator's ability to imitate ACWs in additional scenarios and avoid constant tuning. Closed-loop control can enhance stomach simulators in accuracy, responding to various food and drug contents, timing, and unknown disturbances. In this article, a new generation of anatomically realistic soft pneumatic gastric simulators is designed and fabricated. The presented simulator represents the antrum, the lower portion of the stomach where ACWs occur. It is equipped with a real-time feedback system to implement diverse closed-loop controllers on demand. All the details of the physical design, fabrication, and assembly process are discussed. Also, the measures taken for the mechatronics design and sensory system are highlighted in this article. Through several implementation algorithms and techniques, three closed-loop controllers, including model-based and model-free schemes are designed and successfully applied on the presented simulator to imitate ACWs. All the experimental outcomes are carefully analyzed and compared against the biological counterparts. It is demonstrated that the presented simulator can serve as a reliable tool and method to scrutinize digestion and promote novel technologies around the human stomach and the digestion process. This research methodology can also be utilized to develop other biomimetic and bioinspired applications.

Physiological characterization of gastric emptying using high-resolution antropyloroduodenal manometry.

Delayed gastric emptying (GE) has been associated with antral and pyloric dysmotility. We aimed to characterize differences in the antral, duodenal, and pyloric motility profiles associated with delayed GE, using high-resolution antropyloroduodenal manometry (HR-ADM). Patients referred for HR-ADM for dyspeptic symptoms performed a concurrent GE breath test (NCT01519180 and NCT04918329). HR-ADM involved 36 sensors 1 cm apart, placed across the pylorus. Interdigestive and postprandial periods were identified. Antral, pyloric, and duodenal motor profiles were analyzed recording the frequency, amplitude, and propagative nature of contractions for each period. Plots of patients with normal and delayed GE were compared. Sixty patients underwent both HR-ADM and GE tests. Twenty-five and 35 patients had delayed and normal GE, respectively. Antral and duodenal motor profiles were not different between the two groups during the interdigestive period. During the postprandial period, a lower frequency of antral contractions was associated with delayed GE (2.22 vs. 1.39 contractions/min; P = 0.002), but no difference in mean contraction amplitude was observed. The pyloric region was identified in all the patients and pylorospasms, defined as 3 min of repeated isolated pyloric contractions, were more frequent in patients with delayed GE (32.0% vs. 5.7%; P = 0.02) during the postprandial period. No difference in duodenal contraction profiles was observed. Manometric profile alterations were observed in 72% of the patients with delayed GE, with 56% having a low frequency of antral contractions. Using HR-ADM, patients with delayed GE displayed different postprandial antropyloric motility as compared with patients with normal GE.NEW & NOTEWORTHY High-resolution antropyloroduodenal manometry (HR-ADM) allows precise characterization of antral, pyloric, and duodenal motility, although its association with gastric emptying (GE) has been poorly investigated. Concurrent HR-ADM with GE measurement showed a lower frequency of antral postprandial contractions and an increased frequency of postprandial pylorospasms in patients with delayed GE. HR-ADM could, therefore, be useful in the future to better select patients for treatments targeting the pylorus.

Effect of marination in lemon juice on beef tenderization and in vitro gastric digestibility.

There is limited knowledge regarding digestion and absorption of nutrients after cooked marinated meat is ingested. Most of the previous studies on food gastric digestion have focused on chemical digestion and did not reflect upon physical digestion driven by peristalsis. In the present study, we examined the effects of marinating beef in lemon juice on gastric digestibility using a human gastric digestion simulator (GDS) that mimics peristaltic motion called antral contraction waves. Beef thigh slices were marinated in 100% lemon juice for 1 h and then grilled; an image of a stained tissue sample revealed that muscle tissue contraction (i.e. that usually occurs upon cooking) was suppressed. The measurement of physical properties using a rheometer and texture analyzer showed that the meat marinated in lemon juice had a soft texture. In vitro digestion experiments using the GDS revealed that the extent of both physical digestion driven by peristalsis and chemical digestion catalyzed by digestive enzymes was enhanced by the lemon juice marinade. The results of the present study suggest that marinating beef in lemon juice affects nutrient digestibility. An integrated evaluation of tissue structure, physical properties and GDS digestion to analyze meat digestion would enhance our understanding of the effects of seasoning and cooking methods on meat. © 2023 Society of Chemical Industry.

Ultrasonography findings in diabetes and diabetes gastroparesis: A meta-analysis

Background: The gold standard for diagnosis of diabetes gastroparesis (DG) is with gastric emptying scintigraphy (GES) examination. However, GES is not available in every healthcare center worldwide and the examination cost is rather expensive, unlike ultrasonography (USG) examination. This study aims to evaluate gastric changes monitored with USG in diabetes mellitus (DM) and DG. Methods: We performed searches from Google Scholar, PubMed, Science Direct, Proquest, and Scopus in April 30 – May 6, 2022. Random-effect approach on outcomes, standardized mean-difference (SMD) and 95%-confidence interval (CI) was assessed. Results: Compared to healthy control; (1) Antral cross-sectional area (CSA) in DM is bigger in fasting (SMD=1.25cm2; 95%CI, 0.79 to 1.71, I2=81%, P&lt;0.05) and postprandial (SMD=3.70 cm2; 95%CI, 1.45 to 5.34, I2=85%, P&lt;0.05). (2) Gastric emptying time (GET) is longer with DG (SMD=75.44min; 95%CI, 31.61 to 119.27, I2=97%) and in DM (SMD=35.54min; 95% CI, 11.49 to 59.60, I2=94%). (3) Gastric half-emptying time (GE50) were found to be longer in DM (SMD=20.73 min; 95%CI, 14.69 to 26.77, I2=60%, P&lt;0.05) and DG (SMD=7.46min; 95%CI, 5.06 to 9.86, I2=68.2%, P&lt;0.05). (4) Smaller gastric emptying rate (GER) in DG (SMD=-31.95%; 95%CI, -42.22% to -21.69%, I2=84%, P&lt;0.05) and DM (SMD=-16.14%; 95%CI, -30.88% to -1.39%, I2=78%, P&lt;0.05). (5) Less antral contraction in DG (SMD=-1.47; 95%CI, -2.61 to -0.33, I2=82%, P&lt;0.05). Conclusions: Patients with DM and DG have wider antral CSA, longer GET and GE50, reduced GER and reducing antral contraction. USG is useful for assessing gastric emptying in DM and DG. PROSPERO registration: CRD42022328695 (10/05/2022)

Efficacy of metoclopramide for prevention of gastric regurgitation during endotracheal intubation in the emergency department: A randomized controlled trial.

Gastric content regurgitation and aspiration are the dreaded complications of securing the airway. Cricoid pressure hinders intubation and causes lower esophageal sphincter (LES) relaxation. A recent study suggests no added benefit of cricoid pressure in preventing pulmonary aspiration of gastric contents. Metoclopramide increases LES tone, prevents gastroesophageal reflux, and increases antral contractions. Hence, we wanted to study the efficacy of metoclopramide for preventing gastric regurgitation during endotracheal intubation (ETI) in patients presenting to the emergency department (ED). This study was a randomized controlled trial in patients requiring ETI in the ED. The study participants were randomized to receive either metoclopramide (intervention) 10 mg/2 ml intravenous (IV) bolus or a placebo of normal saline (placebo) 2 ml IV bolus 5 min before rapid sequence induction and intubation. The outcome of the study was the visualization of gastric regurgitation at the glottic opening during direct laryngoscopy at the time of intubation. Seventy-four study participants were randomized and allocated to the metoclopramide group (n = 37) or placebo group (n = 37). Gastric regurgitation at the glottis was noted in three study participants (8%) in the metoclopramide group, and six (16%) in the placebo group (odds ratio [OR] - 0.456; 95% confidence interval [CI] of 0.105-1.981; P = 0.295). The study participants who were intubated in the first attempt had less gastric regurgitation compared to ≥2 attempts (OR 0.031; 95% CI of 0.002-0.511; P = 0.015). There was no decrease in regurgitation with metoclopramide as compared to placebo during ETI in study participants presenting to the ED.

Mfge8 is expressed by pericytes in gastric antrum submucosa from patients with obesity.

The main function of the stomach is to digest ingested food. Gastric antrum muscular contractions mix ingested food with digestive enzymes and stomach acid and propel the chyme through the pyloric sphincter at a rate in which the small intestine can process the chyme for optimal nutrient absorption. Mfge8 binding to α8β1 integrins helps regulate gastric emptying by reducing the force of antral smooth muscle contractions. The source of Mfge8 within gastric muscles is unclear. Since Mfge8 is a secreted protein, Mfge8 could be delivered via the circulation, or be locally secreted by cells within the muscle layers. In this study, we identify a source of Mfge8 within human gastric antrum muscles using spatial transcriptomic analysis. We show that Mfge8 is expressed in subpopulations of Mef2c+ perivascular cells within the submucosa layer of the gastric antrum. Mef2c is expressed in subpopulations of NG2+ and PDGFRB+ pericytes. Mfge8 is expressed in NG2+/Mef2c+ pericytes, but not in NG2+/Mef2c-, PDGFRB+/Mef2c-, or PDGFRB+/Mef2c+ pericytes. Mfge8 is absent from CD34+ endothelial cells but is expressed in a small population of perivascular ACTA2+ cells. We also show that α8 integrin is not expressed by interstitial cells of Cajal (ICC), supporting the findings that Mfge8 attenuates gastric antrum smooth muscle contractions by binding to α8β1 integrins on enteric smooth muscle cells. These findings suggest a novel, supplementary mechanism of regulation of gastric antrum motility by cellular regulators of capillary blood flow, in addition to the regulation of gastric antrum motility by the enteric nervous system and the SMC, ICC, and PDGFRα+ cell (SIP) syncytium.

Fourier Phase Analysis of Dynamic Antral Contraction Scintigraphy: New Software, Reference Values, and Comparisons to Conventional Gastric Emptying.

Dynamic antral contraction scintigraphy (DACS) has been used to evaluate for gastric dysmotility by measuring antral contraction frequency and ejection fraction (EF). Fourier phase image analysis has the potential to assess gastric antral contractions for dyssynchrony as has been used for analyzing nuclear cardiology ventriculography (multigated acquisition studies) for cardiac dyssynchrony. The aims of this study were to determine whether Fourier phase analysis helps to characterize antral motility physiology, whether Fourier phase analysis correlates with conventional gastric emptying scintigraphy (GES), and which DACS parameters may aid in diagnosing gastric dysmotility, particularly delayed gastric emptying (GE). Methods: DACS and GES of healthy volunteers (n = 22) were compared with patients (n = 99) with symptoms of gastroparesis. New DACS Fourier phase analysis software was developed. Results: GE was delayed (n = 53) or normal (n = 46) in patients. There was a linear correlation between the time for the stomach to empty 50% of the meal and the percentage total proximal and distal in-phase antral pixels at 30 min (r = 0.37, P = 0.0001) and 60 min (r = 0.26, P = 0.007). In healthy volunteers, the mean proximal-to-distal ratio of in-phase antral pixels increased from 1.67 (30 min) to 2.65 (120 min) (P = 0.035), and EF increased from 23% (30 min) to 32% (120 min) (P = 0.022). Multivariable regressions of percentage total proximal and distal in-phase antral pixels (30 min) and EF (60 min) were the best predictors of abnormal GE (adjusted odds ratio, 3.30 [95% CI, 1.21-9.00] and 2.97 [95% CI, 1.08-8.21], respectively). Conclusion: This study used Fourier phase analysis to analyze DACS in healthy volunteers and patients with symptoms of gastroparesis. In addition to establishing reference values, new physiologic information on antral motility was obtained. In healthy volunteers, there was an increasing proximal-to-distal ratio of in-phase antral pixels and antral EF over time after meal ingestion. The percentage total proximal and distal in-phase antral pixels at both 30 and 60 min correlated well with GE values for the time for the stomach to empty 50% of the meal. For symptomatic patients, the percentage total proximal and distal in-phase antral pixels at 30 min and the EF at 60 min after meal ingestion correlated with delayed GE on conventional GES. Thus, Fourier phase analysis of DACS appears to have potential to further aid in diagnosing gastric dysmotility in GES.

Three-dimensional multi-field modelling of gastric arrhythmias and their effects on antral contractions

The contraction activation of smooth muscle in the stomach wall (SW) is coordinated by slow electrical waves. The interstitial cells of Cajal (ICC), specialised pacemaker cells, initiate and propagate these slow waves. By establishing an electrically coupled network, each ICC adjusts its intrinsic pacing frequency to a single dominant frequency, to be a key aspect in modelling the electrophysiology of gastric tissue. In terms of modelling, additional fields associated with electrical activation, such as voltage-dependent calcium influx and the resulting deformation, have hardly been considered so far. Here we present a three-dimensional model of the electro-chemomechanical activation of gastric smooth muscle contractions. To reduce computational costs, an adaptive multi-scale discretisation strategy for the temporal resolution of the electric field is used. The model incorporates a biophysically based model of gastric ICC pacemaker activity that aims to simulate stable entrainment and physiological conduction velocities of the electrical slow waves. Together with the simulation of concomitant gastric contractions and the inclusion of a mechanical feedback mechanism, the model is used to study dysrhythmias of gastric slow waves induced by abnormal stretching of the antral SW. The model is able to predict the formation of stretch-induced gastric arrhythmias, such as the emergence of an ectopic pacemaker in the gastric antrum. The results show that the ectopic event is accompanied by smooth muscle contraction and, although it disrupts the normal propagation pattern of gastric slow electrical waves, it can also catalyse the process of handling indigestible materials that might otherwise injure the gastric SW.

SoRSS: A Soft Robot for Bio-Mimicking Stomach Anatomy and Motility.

A human stomach is an organ in the digestive system that breaks down foods by physiological digestion, including mechanical and chemical functions. The mechanical function is controlled by peristaltic waves generated over the stomach body, known as antral contraction waves (ACW). The stomach's physiological digestion is essential to sustain nutrition and health in humans. Replicating the digestion process in a robot provides a test environment as an alternative solution to in vivo testing, which is difficult in practice. Stomach robots made of rigid rods and metal cylinders are unrealistic replicas to contract and expand like biological examples. With soft robotics technology, it is possible to translate biological behavior into an engineering context. Soft robotics introduce potential methods to replicate peristaltic waves and achieve a soft-bodied stomach simulator. This work presents a soft robotic stomach simulator's (SoRSS) concept, design, and experimental validation. A pneumatic bellows actuation for linear elongation and a ring of bellows actuation for circular contraction are proposed first. Multi-ring actuators are then arranged to form an SoRSS that generates ACW and antral contracting pressure (ACP). The SoRSS satisfies the specification of human stomach anatomy and motility and finally undergoes experimental validation using videofluoroscopy with the outcomes presenting the ACW, ACP, and the digestion phases during the actuation process. Those are compared with other medical studies to validate SoRSS functionality.

Comprehensive characterization of antral and pyloric contractions by high resolution manometry: applied physiology in suspected gastroparesis.

Delayed gastric emptying may result from diverse pathophysiological mechanisms including antral hypomotility and pylorospasm. With increasing use of gastric peroral endoscopic myotomy and preliminary evidence of efficacy, our aim was to assess the motor functions of the distal antrum and pylorus in patients with symptoms of gastroparesis using high-resolution antropyloroduodenal manometry (HR-ADM). Sixteen patients with symptoms suggestive of gastroparesis underwent HR-ADM with 13 sensors, 1 cm apart, placed across the antropyloroduodenal (APD) junction and 2 sensors, 10 cm apart, in descending and distal duodenum. The 1-h postprandial motility was quantitated as contraction frequency/minute, average amplitude, and motility index (MI). Six healthy volunteers served as controls. In the patient group, the HR-ADM identified postprandial antral hypomotility, isolated pyloric pressure waves, and tonic elevation of baseline pressure in pylorus. Patients had significantly reduced frequency of the full-hour postprandial antral contractions/minute compared with healthy volunteers [1.52 (0.97, 1.67) vs. 2.04 (1.70, 2.67), P = 0.005], as well as reduced MI [9.65 (8.29, 10.31) vs. 11.04 (10.65, 11.63), P = 0.002]. The average contraction amplitude was numerically, but not significantly reduced [51.9 (21.9, 74.9) vs. 73.0 (59.8, 82.7), P = 0.14]. Bland-Altman plots showed similar distribution of antral contraction frequency and MI during the first and second postprandial 30-min periods for both patients and controls. High-resolution ADM can characterize a variety of postprandial antral contractile and pyloric motility dysfunctions. This technique shows promise to provide guidance for the selection of optimal treatment of patients with gastroparesis.NEW & NOTEWORTHY Current selection of different treatments for patients with gastroparesis is empiric or based on trial and error, though pyloric distensibility and diameter may predict response to pyloric interventions. High-resolution antropyloroduodenal manometry (HR-ADM) can characterize a variety of postprandial antral contractile and pyloric motility dysfunctions in patients with suspected gastroparesis. HR-ADM shows promise to provide guidance for selection and individualization of treatments such as prokinetic agents or pyloric interventions for patients with gastroparesis based on documented pathophysiology.

Vomiting and Gastric Motility in Early Brain Damaged Children With Congenital Zika Syndrome.

This study investigated the occurrence of vomiting and gastric dysmotility in dysphagic children with congenital Zika syndrome (CZS) and assessed possible associations of these findings with the severity of dysphagia and the presence of tube feeding. Forty-six children with CZS were assessed for dysphagia, and the occurrence of vomiting, dietary volume tolerance <15 mL/kg, and feeding time per meal >30 minutes were evaluated. Gastric antrum ultrasonography was used to detect the frequency of contractions and measure antral areas (at fasting and 15 minutes postprandial), from which the gastric emptying rate (GER) was calculated. Antral ultrasonography findings were compared with those of ten healthy controls. Vomiting and gastric motility were compared between CZS patients according to the severity of dysphagia and the requirement for tube feeding. Overall, 76% (35/46) of children with CZS had moderate-to-severe dysphagia (MSD), among whom 60% (21/35) were tube fed [MSD tube fed (MSDTF)]. Vomiting occurred in 54% (25/46) of children, whereas dietary volume intolerance and prolonged feeding time were observed in 59% (27/46) and 37% (17/46), respectively, most frequently in MSDTF patients. On ultrasound, 61% (28/46) of children with CZS had no antral contractions, whereas 90% (9/10) of controls did. Compared to healthy controls, GER was eight-fold lower in children with CZS and 60-fold lower in MSDTF children. In dysphagic children with CZS, vomiting, volume intolerance, and prolonged feeding time were frequent and possibly associated with impaired antral contraction and delayed gastric emptying, especially in cases of severe dysphagia and tube feeding.

Computational Modeling of Drug Dissolution in the Human Stomach.

A computational model of drug dissolution in the human stomach is developed to investigate the interaction between gastric flow and orally administrated drug in the form of a solid tablet. The stomach model is derived from the anatomical imaging data and the motion and dissolution of the drug in the stomach are modeled via fluid-structure interaction combined with mass transport simulations. The effects of gastric motility and the associated fluid dynamics on the dissolution characteristics are investigated. Two different pill densities are considered to study the effects of the gastric flow as well as the gravitational force on the motion of the pill. The average mass transfer coefficient and the spatial distributions of the dissolved drug concentration are analyzed in detail. The results show that the retropulsive jet and recirculating flow in the antrum generated by the antral contraction wave play an important role in the motion of the pill as well as the transport and mixing of the dissolved drug concentration. It is also found that the gastric flow can increase the dissolution mass flux, especially when there is substantial relative motion between the gastric flow and the pill.

Luminal Chemoreceptors and Intrinsic Nerves: Key Modulators of Digestive Motor Function.

This chapter reviews data on the pathways by which luminal, mainly duodenal, chemoreceptors modulate gastro-pyloro-duodenal motor function to control emptying of nutrients into the small intestine. The vagus mediates proximal gastric relaxation caused by nutrient stimulation of duodenal/jejunal mucosal chemoreceptors. Modulation of the spatial patterning and inhibition of antral contractions during duodenal chemoreceptor activation are somewhat conflicting: both vagal control and ascending intramural nerves appear to play a role. Intraduodenal nutrients stimulate the localized pyloric contractions that prevent transpyloric flow via ascending duodenal intramural nerve pathways. Though not yet formally investigated, patterns of activation of the duodenal brake motor mechanism suggest that duodenal loop mucosal chemoreceptors signal to a brake mechanism at the most aborad region of the duodenum via descending intramural duodenal nerves.Intrinsic intramural pathways are important in the control of the first stages of digestion.

Antral contractility following Asian-style meal in healthy volunteers: effect of genders, menstruation, smoking status and age

Objective(s):The normal range of the frequency of antral contractions, similar to other gastric motility parameters, are different depending on the population and the test meal. We, therefore, conducted the analysis to establish the normal ranges for the frequency of antral contractions derived from dynamic antral scintigraphy (DAS) following an Asian-styled solid meal in Thai healthy volunteers.Methods:We retrospectively analyzed the data from the study on normal gastric emptying values. The dynamic scintigraphic images had been obtained in a 45 degree left anterior oblique view during the first 32 minutes following the ingestion of a 267-kcal steamed rice, a technetium-99m-labeled microwaved egg and 100 mL of water. A polynomial normalization model was used to analyze and to calculate the frequency of antral contractions. The data analysis was repeated by the same operator 1 month apart to assess reproducibility.Results:Data of 18 volunteers (10 males and 8 females) were eligible for analysis. The mean±SD of the frequencies of the antral contractions were 3.06±1.08 cycles/min on the first and 3.04±1.10 cycles/min on the second analysis. Comparison of the two analyses revealed a moderate agreement (ICC=0.632, 95% CI 0.329-0.818) without significant difference (p-value=0.942). No significant effect of gender, menstruation status, smoking or age was demonstrated in this study.Conclusion:DAS is a non-invasive technique that can measure the frequency of antral contractions. The technique is reproducible and consistent. Future study may be required to assess the effect of gender, menstruation status, smoking and age.

Effect of acupuncture at Zusanli\xa0(ST36) point on antral contraction function under ultrasound guidance: study protocol of a randomized controlled trial

BackgroundAlthough the relationship between deqi sensations and curative effect has always been controversial, deqi sensations has been regarded as the key indicator of clinical efficacy of acupuncture therapy. There is little evidence for standardization or visualization of the mechanism of acupuncture’s therapeutic effect. This trial aims to evaluate the effect of needling at Zusanli (ST36) on antral contraction function as visualized by ultrasound.MethodsThis is a two-arm, single-blind, randomized, controlled trial. A total of 116 acupuncture-naïve healthy subjects will be randomly allocated to the acupuncture group or sham acupuncture group in a 1:1 ratio. Participants in the acupuncture group will receive manual acupuncture at Zusanli (ST36) with the needling depth at crural interosseous membrane. Those in the sham acupuncture group will be given penetrating needling depth at the superficial fascia layer. The primary outcome will be the changes in antral contraction frequency (ACF) before and after acupuncture. The secondary outcomes will be the changes in the thermal infrared spectrum of gastric area skin, the antral contraction amplitude (ACA), the antral movement index (AMI), and the scores on the Chinese version of Massachusetts General Hospital Acupuncture Sensation Scale (C-MASS). The adverse events will be evaluated and recorded in detail.DiscussionThis study may provide visual and objective evidence regarding the safety and efficacy of manual acupuncture at Zusanli (ST36). In addition, the results of this study will help to identify the role of Zusanli (ST36)in the inducing deqi.Trial registrationChinese Clinical Trial Registry ChiCTR2000040686. Registered on 8 December 2020

Investigation of the dispersing characteristics of antral contraction wave flow in a simplified model of the distal stomach

The dispersing characteristics of antral contraction wave (ACW) flow in the antrum are investigated by reproducing the flow generated by an ACW and determining its effect on liquid drops. The goal is to gain information about the flow field and mechanical stresses, which are responsible for the food disintegration. Toward this end, a model antrum prototype was constructed, consisting of a cylinder that was closed at one end to represent the antrum and closed pylorus. A moving hollow piston with a parabolic inner contour was used to model an ACW. A computational model was developed that reflects this prototype. Experiments and simulations were first performed for fluids with different rheological properties, two relative occlusions (0.60 and 0.75), and several ACW speeds (1.0–7.5 mm/s). The simulations were validated with velocity measurements, and the characteristics of the retropulsive jet were quantified at different Reynolds numbers (0.5–105.3). Experiments were then performed in which liquid drops of different viscosity were placed in a highly viscous fluid with low interfacial tension, similar to conditions in a stomach. It was found that the viscosity ratio (0.001–0.1) influences the retraction dynamics of a drop's tail after stresses are relaxed. The flow and stress information from the simulations was used to analyze fluid transport in the antrum and to quantify drop breakup conditions. It was found that a drop broke up if both a critical capillary number of 0.51 was exceeded and the drop passed within a critical dimensionless distance of 0.3 to the wave apex.

Effects of Provocative Testing on Phase III Migrating Motor Complex in Children.

Antroduodenal manometry (ADM) is used to evaluate antral and small intestinal motility, with the presence of phase III migrating motor complexes (MMCs) indicating an intact enteric neuromuscular system. The lack of evidence-based or consensus-driven established norms for MMC in fasting phase and after provocative testing marks a major limitation in the interpretation of ADM studies. We aimed to determine the characteristics of MMC in fasting and post-provocative phase in children. Data from subjects ages <20 years with ADM results evaluated at neuro-gastroenterology and Motility Disorders Center, Cincinnati Children's Hospital Medical Center from January 2018 to March 2019 were analyzed. Forty-eight ADM tracings that did not demonstrate abnormal patterns were included; the mean age was 10.00 ± 5.72 years and 50% were male. Indications for ADM included: vomiting (27.1%), feeding intolerance (27.1%), abdominal pain (16.6%), nausea (14.6%), and abdominal distension (14.6%). Thirty-seven percent of subjects had enteral access for feeds. During fasting, one-third of all MMC originated in the antrum. Azithromycin-induced MMC occurred in 28% of subjects and two-thirds of these originated in the antrum with antral contractions of significantly higher frequency and amplitude compared to fasting. Octreotide significantly increased frequency, amplitude, and duration of MMC compared to fasting, with 76% originating in the antrum. Both azithromycin and octreotide induced more than one MMC in a third of subjects. We describe the characteristics of antral and small intestinal motility during fasting and after provocative testing in children. These values will help standardize our interpretation of pediatric ADM studies.

A hierarchical model of abdominal configuration changes extracted from golden angle radial magnetic resonance imaging

Abdominal organs are subject to a variety of physiological forces that superimpose their effects to influence local motion and configuration. These forces not only include breathing, but can also arise from cyclic antral contractions and a range of slow configuration changes. To elucidate each individual motion pattern as well as their combined effects, a hierarchical motion model was built for characterization of these 3 motion modes (characterized as deformation maps between states) using golden angle radial MR signals. Breathing motions are characterized first. Antral contraction states are then reconstructed after breathing motion-induced deformation are corrected; slow configuration change states are further extracted from breathing motion-corrected image reconstructions. The hierarchical model is established based on these multimodal states, which can be either individually shown or combined to demonstrate any arbitrary composited motion patterns. The model was evaluated using 20 MR scans acquired from 9 subjects. Poor reproducibility of breathing motions both within as well as between scan sessions was observed, with an average intra-subject difference of 1.6 cycles min−1 for average breathing frequencies of 12.0 cycles min−1. Antral contraction frequency distributions were more stable than breathing, but also presented poor reproducibility between scans with an average difference of 0.3 cycles min−1 for average frequencies of 3.2 cycles min−1. The magnitudes of motions beyond breathing were found to be significant, with 14.4 and 33.8 mm maximal motions measured from antral contraction and slow configuration changes, respectively. Hierarchical motion models have potential in multiple applications in radiotherapy, including improving the accuracy of dose delivery estimation, providing guidance for margin creation, and supporting advanced decisions and strategies for immobilization, treatment monitoring and gating.

Age as a dominant factor affecting gastric motility and emptying

Gastric motility is the process of continuous propagation of peristaltic waves from the anterior part of the stomach to the pylorus region. These waves aid in the digestion of foods, importantly play a major role in gastric emptying of foods. The present study aimed to investigate whether ageing influences gastric motility in response to apple consumption. Subjects were asked to consume apple and water in the ratio of 3:1 followed by MRI scanning in the right lying position. Antral contraction wave characteristics like speed, frequency, amplitude and width of the wave and occlusion percentage were calculated. Average contractions per minute were obtained as 2.67±0.06 for young age and 2.43±0.22 for middle-aged healthy humans. From the obtained results, no significant difference was found between the assessed motility parameters.