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In vivo vagus nerve stimulation holds great promise in regulating food intake for obesity treatment. Here we present an implanted vagus nerve stimulation system that is battery-free and spontaneously responsive to stomach movement. The vagus nerve stimulation system comprises a flexible and biocompatible nanogenerator that is attached on the surface of stomach. It generates biphasic electric pulses in responsive to the peristalsis of stomach. The electric signals generated by this device can stimulate the vagal afferent fibers to reduce food intake and achieve weight control. This strategy is successfully demonstrated on rat models. Within 100 days, the average body weight is controlled at 350 g, 38% less than the control groups. This work correlates nerve stimulation with targeted organ functionality through a smart, self-responsive system, and demonstrated highly effective weight control. This work also provides a concept in therapeutic technology using artificial nerve signal generated from coordinated body activities. Developing new technologies for the neuromodulation of the vagus nerve can enable therapeutic strategies for body weight control in obese patients. Here, the authors present a battery-free self-powered implantable vagus nerve stimulation system that electrically responds to stomach movement.

A human gut-on-a-chip microdevice was used to coculture multiple commensal microbes in contact with living human intestinal epithelial cells for more than a week in vitro and to analyze how gut microbiome, inflammatory cells, and peristalsis-associated mechanical deformations independently contribute to intestinal bacterial overgrowth and inflammation. This in vitro model replicated results from past animal and human studies, including demonstration that probiotic and antibiotic therapies can suppress villus injury induced by pathogenic bacteria. By ceasing peristalsis-like motions while maintaining luminal flow, lack of epithelial deformation was shown to trigger bacterial overgrowth similar to that observed in patients with ileus and inflammatory bowel disease. Analysis of intestinal inflammation on-chip revealed that immune cells and lipopolysaccharide endotoxin together stimulate epithelial cells to produce four proinflammatory cytokines (IL-8, IL-6, IL-1β, and TNF-α) that are necessary and sufficient to induce villus injury and compromise intestinal barrier function. Thus, this human gut-on-a-chip can be used to analyze contributions of microbiome to intestinal pathophysiology and dissect disease mechanisms in a controlled manner that is not possible using existing in vitro systems or animal models.

Bingham plastic fluids are frequently found in both biological and industrial contexts, especially in situations requiring the movement of mucus, chyme, or blood that has unusual viscosity through microchannels. Inspired by the function of cilia-driven peristalsis in biological transport, this research presents a new mathematical model for the peristaltic motion of a Bingham plastic fluid that contains active microorganisms within an asymmetric microchannel incorporating slip boundary effect. The primary partial differential equations governing momentum, heat, concentration, and the transport of microorganisms are transformed into a non-dimensional format based on the assumptions of long wavelength and low Reynolds number. By utilizing suitable scaling parameters, the system is simplified to a pair of nonlinear ordinary differential equations. The slip effects are included along the channel walls, and the cilia-induced movement is represented through parameters relating to eccentricity and cilia length. The obtained equations, together with the relevant boundary conditions, are solved numerically using the bvp4c method in MATLAB. The findings indicate that slip increases the velocity near the walls of the channel, but decreases it in the core of the channel. A rise in the Bingham number diminishes fluid trapping, whereas a greater eccentricity enhances pumping efficiency by decreasing recirculating bolus regions. The temperature rises due to heat generation and Joule heating but is lowered by thermal radiation and heat sink effects. Concentration declines with an increase in Schmidt number and chemical reactions, while the density of microorganisms decreases with thermophoresis, bioconvection constant, and Peclet number. The novelty of this study lies in integrating the Bingham plastic rheology with cilia-induced wall motion, slip effects, and microorganism transport in an asymmetric channel. This fills a gap in the existing literature where such a combination has not been previously addressed, despite its strong relevance to physiological flows such as mucus clearance, chyme transport, and biomedical peristaltic pump design.

Patient responses to immune checkpoint inhibitors can be influenced by the gastrointestinal microbiome. Mouse models can be used to study microbiome–host crosstalk, yet their utility is constrained by substantial anatomical, functional, immunological and microbial differences between mice and humans. Here we show that a gut-on-a-chip system mimicking the architecture and functionality of the human intestine by including faecal microbiome and peristaltic-like movements recapitulates microbiome–host interactions and predicts responses to immune checkpoint inhibitors in patients with melanoma. The system is composed of a vascular channel seeded with human microvascular endothelial cells and an intestinal channel with intestinal organoids derived from human induced pluripotent stem cells, with the two channels separated by a collagen matrix. By incorporating faecal samples from patients with melanoma into the intestinal channel and by performing multiomic analyses, we uncovered epithelium-specific biomarkers and microbial factors that correlate with clinical outcomes in patients with melanoma and that the microbiome of non-responders has a reduced ability to buffer cellular stress and self-renew. The gut-on-a-chip model may help identify prognostic biomarkers and therapeutic targets. A gut-on-a-chip incorporating peristaltic-like movements and faecal samples from patients with melanoma recapitulates microbiome–host interactions and predicts the responses of the patients to immune checkpoint inhibitors.

Background Uterine contractions, also known as peristalsis, have been shown to affect fertility. However, despite previous studies, most clinicians have not paid sufficient attention to uterine peristalsis. Recent studies have recognised its importance and evaluated contractility parameters prior to embryo transfer. Method A systematic literature search was conducted in Medline, Embase and Cochrane CENTRAL up to January 2024. Inclusion criteria were studies involving patients undergoing in vitro fertilization (IVF) or other infertility treatments in which uterine contractility was assessed. Studies were excluded if they included therapeutic interventions that affected contractility, or if they focused on uterine pathologies such as adenomyosis or fibroids. The meta-analysis included trials with IVF treatments that compared clinical pregnancy rates in women with high versus low frequent uterine contractions. Results A total of 2587 women (17 studies) were included in the systematic review, of whom 1134 (43.1%) (5 studies) underwent embryo transfer and were eligible for meta-analysis. The review found that elevated contractility on the day of embryo transfer is associated with a negative impact on pregnancy rates. The meta-analysis showed that women with two or more uterine contractions at the time of the embryo transfer had a significantly lower clinical pregnancy rate than with women with two or fewer contractions (OR 0.52, 95% CI: 0.38- 0.69). There was moderate heterogeneity between studies (I 2  = 55, p  < 0.01). Conclusions The lower clinical pregnancy rate in women with high uterine contractility, highlights the role of uterine peristalsis around the time of embryo implantation. However, due to the limited and heterogeneous data available, the influence of uterine peristalsis on reproductive outcomes such as live birth rates remains unclear.

In this paper, we develop a combination of algorithms, including camera motion detector (CMD), deep learning models, class activation mapping (CAM), and periodical feature detector for the purpose of evaluating human gastric motility by detecting the presence of gastric peristalsis and measuring the period of gastric peristalsis. Moreover, we use visual interpretations provided by CAM to improve the sensitivity of the detection results. We evaluate the performance of detecting peristalsis and measuring period by calculating accuracy, F1, and area under curve (AUC) scores. Also, we evaluate the performance of the periodical feature detector using the error rate. We perform extensive experiments on the magnetically controlled capsule endoscope (MCCE) dataset with more than 100,000 frames (100,055 specifically). We have achieved high accuracy (0.8882), F1 (0.8192), and AUC scores (0.9400) for detecting human gastric peristalsis, and low error rate (8.36%) in measuring peristalsis periods from the clinical dataset. The proposed combination of algorithms has demonstrated the feasibility of assisting in the evaluation of human gastric motility.

Bitter taste receptors (TAS2Rs) are expressed in extraoral tissues, exerting several functions and generating a whole-body chemosensory and protective system. TAS2Rs expression has been observed in the gastrointestinal tract, although their role is poorly understood. This study aims to investigate the role of TAS2R38 and 46 in human intestinal smooth muscle cells (HISMCs) after activation with the specific bitter ligands phenylthiocarbamide and absinthin, respectively. We found that TAS2R38 and 46 activation by phenylthiocarbamide (PTC) and absinthin, respectively, induces a rapid membrane depolarization and increase of cytosolic calcium levels due to internal storage in the IP3 pathway, resulting in an accelerated cell contraction. Overall, this study unravels, for the first time, the contractile impact of these TAS2R subtypes on intestinal smooth muscle cells, suggesting their involvement in gut peristalsis and recommending these receptors as possible targets for new therapies.

Constipation and other digestive disorders are common in older adults. The autonomic nervous system plays a critical role in regulating digestive motility in the intestinal tract. However, studies on age-related changes in autonomic function and receptor expression in the intestinal tract are limited. In this study, we examined the expression of neurotransmitter receptors in the autonomic nervous system and the effects of acetylcholine and β-agonists on intestinal contraction and relaxation in the jejunum of aged rats. Jejunal sections collected from male and female Wistar/ST rats aged 4, 11, and 18 months were analyzed. Immunohistochemical staining and enzyme-linked immunosorbent assay were used to measure the expression of muscarinic acetylcholine receptors (CHRM2 and CHRM3) and β-adrenergic receptors (β2-ADR and β3-ADR). The effects of acetylcholine, isoproterenol, and mirabegron were assessed in the isolated jejunum for each age group. There was no significant difference in CHRM2 receptor expression among the age groups; however, CHRM3 receptor expression decreased with age. Additionally, the sensitivity to acetylcholine-induced contractile responses decreased with age. Although β2-ADR receptor expression did not differ among the age groups, β3-ADR receptor expression increased with age. Despite this, the relaxation response to isoproterenol and mirabegron decreased with age. Our study revealed an age-related decrease in CHRM3 expression and the contractile response to acetylcholine in the small intestine of rats. Although β-ADR expression, particularly β3-ADR, increased with age, the relaxation response to β-adrenergic agonists gradually decreased.

Achalasia is an esophageal motility disorder characterized by aberrant peristalsis and insufficient relaxation of the lower esophageal sphincter. Patients most commonly present with dysphagia to solids and liquids, regurgitation, and occasional chest pain with or without weight loss. High-resolution manometry has identified 3 subtypes of achalasia distinguished by pressurization and contraction patterns. Endoscopic findings of retained saliva with puckering of the gastroesophageal junction or esophagram findings of a dilated esophagus with bird beaking are important diagnostic clues. In this American College of Gastroenterology guideline, we used the Grading of Recommendations Assessment, Development and Evaluation process to provide clinical guidance on how best to diagnose and treat patients with achalasia.

Background It has recently been discovered that one of the key elements influencing endometrial receptivity is uterine peristalsis. This was a prospective cohort study aiming to assess uterine peristalsis at the time of embryo transfer in women undergoing IVF. Methods Uterine peristaltic waves were assessed using transvaginal ultrasound by recording a 3-minute video to determine the frequency and the direction of peristalsis. Primary outcome was clinical pregnancy while secondary outcomes were biochemical pregnancy, miscarriage, ectopic pregnancy and live birth. Outcomes were compared in women who had no peristalsis (Absent group), had one or two waves per minute (< 3 Group), or those who had 3 or more waves per minute (≥ 3 Group). Results Between August 2023 and January 2025, 127 women were included in this study, of whom 76 (59.8%) were fresh cycles and 51 (40.2%) were frozen cycles. The median number of peristaltic waves was one per minute. Peristalsis was absent in 34 women, < 3 in 72 women and ≥ 3 in 21 women. There was no statistically significant difference in pregnancy rate between the three groups (26.1% in absent group, 36.1% in < 3 group, and 33.3% in ≥ 3 group). The direction was cervico-fundal in 62 women, fundo-cervical in 5 women, and random in 26 women, with pregnancy rates 22%, 0% and 11%, respectively, with no statistically significant difference. Conclusion We did not find a significant effect of the number or the direction of uterine peristalsis on any of the clinical outcomes of IVF. Therefore, we do not recommend its routine assessment before embryo transfer until further evidence is available. Trial registration The study protocol was registered on 14 September 2023 at ClinicalTrials.gov (Registration number NCT06036459).