Anatomy and Physiology of the Stomach

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.

The genetic regulation of the gastric transcriptome is associated with metabolic and obesity-related traits and diseases

Tissue-specific gene expression and gene regulation lead to a better understanding of tissue-specific physiology and pathophysiology. We analyzed the transcriptome and genetic regulatory profiles of two distinct gastric sites, corpus and antrum, to identify tissue-specific gene expression and its regulation. Gastric corpus and antrum mucosa biopsies were collected during routine gastroscopies from up to 431 healthy individuals. We obtained genotype and transcriptome data and performed transcriptome profiling and expression quantitative trait locus (eQTL) studies. We further used data from genome-wide association studies (GWAS) of various diseases and traits to partition their heritability and to perform transcriptome-wide association studies (TWAS). The transcriptome data from corpus and antral mucosa highlights the heterogeneity of gene expression in the stomach. We identified enriched pathways revealing distinct and common physiological processes in gastric corpus and antrum. Furthermore, we found an enrichment of the single nucleotide polymorphism (SNP)-based heritability of metabolic, obesity-related, and cardiovascular traits and diseases by considering corpus- and antrum-specifically expressed genes. Particularly, we could prioritize gastric-specific candidate genes for multiple metabolic traits, like NQO1 which is involved in glucose metabolism, MUC1 which contributes to purine and protein metabolism or RAB27B being a regulator of weight and body composition. Our findings show that gastric corpus and antrum vary in their transcriptome and genetic regulatory profiles indicating physiological differences which are mostly related to digestion and epithelial protection. Moreover, our findings demonstrate that the genetic regulation of the gastric transcriptome is linked to biological mechanisms associated with metabolic, obesity-related, and cardiovascular traits and diseases. NEW & NOTEWORTHY We analyzed the transcriptomes and genetic regulatory profiles of gastric corpus and for the first time also of antrum mucosa in 431 healthy individuals. Through tissue-specific gene expression and eQTL analyses, we uncovered unique and common physiological processes across both primary gastric sites. Notably, our findings reveal that stomach-specific eQTLs are enriched in loci associated with metabolic traits and diseases, highlighting the pivotal role of gene expression regulation in gastric physiology and potential pathophysiology.

A Window for Enhanced Oral Delivery of Therapeutics via Lipid Nanoparticles

Oral administration of dosage forms is convenient and beneficial in several respects. Lipid nanoparticulate dosage forms have emerged as a useful carrier system in deploying low solubility drugs systemically, particularly class II, III, and IV drugs of the Biopharmaceutics Classification System. Like other nanoparticulate delivery systems, their low size-to-volume ratio facilitates uptake by phagocytosis. Lipid nanoparticles also provide scope for high drug loading and extended-release capability, ensuring diminished systemic side effects and improved pharmacokinetics. However, rapid gastrointestinal (GI) clearance of particulate delivery systems impedes efficient uptake across the mucosa. Mucoadhesion of dosage forms to the GI mucosa results in longer transit times due to interactions between the former and mucus. Delayed transit times facilitate transfer of the dosage form across the mucosa. In this regard, a balance between mucoadhesion and mucopenetration guarantees optimal systemic transfer. Furthermore, the interplay between GI anatomy and physiology is key to ensuring efficient systemic uptake. This review captures salient anatomical and physiological features of the GI tract and how these can be exploited for maximal systemic delivery of lipid nanoparticles. Materials used to impart mucoadhesion and examples of successful mucoadhesive lipid nanoformulations are highlighted in this review.

Point of Care Abdominal Ultrasound

Abdominal pain is a common emergency department complaint, and point-of-care ultrasound (POCUS) of the abdomen is increasingly being utilized to evaluate clinical manifestations. It aids in accurate diagnoses and assists in procedures, particularly in emergency and critical care settings. Imaging is often required to confirm the etiology of abdominal pain. POCUS provides the benefit of avoiding radiation exposure and enables quicker diagnosis compared to computed tomography scans. There is growing evidence of the diagnostic accuracy for numerous abdominal POCUS applications, including appendicitis, intussusception, diverticulitis, gastric ultrasound and contrast-enhanced ultrasound.

Endoscopic Resection of Early Luminal Cancer

Gastrointestinal cancers can have severe consequences if diagnosed at a late stage but can be cured when detected and resected at an early stage. In recent years, the significance of endoscopic screening for gastrointestinal cancers has been established, leading to the identification of early-stage cancers and precancerous lesions. Consequently, endoscopic removal of gastrointestinal tumors has emerged as an effective means of cancer treatment and prevention. This article delves into the indications, techniques, and safety measures associated with endoscopic resection of early-stage luminal cancer within the gastrointestinal tract.

Oral nanomedicine biointeractions in the gastrointestinal tract in health and disease

Oral administration is the preferred route of administration based on the convenience for and compliance of the patient. Oral nanomedicines have been developed to overcome the limitations of free drugs and overcome gastrointestinal (GI) barriers, which are heterogeneous across healthy and diseased populations. This review aims to provide a comprehensive overview and comparison of the oral nanomedicine biointeractions in the gastrointestinal tract (GIT) in health and disease (GI and extra-GI diseases) and highlight emerging strategies that exploit these differences for oral nanomedicine-based treatment. We introduce the key GI barriers related to oral delivery and summarize their pathological changes in various diseases. We discuss nanomedicine biointeractions in the GIT in health by describing the general biointeractions based on the type of oral nanomedicine and advanced biointeractions facilitated by advanced strategies applied in this field. We then discuss nanomedicine biointeractions in different diseases and explore how pathological characteristics have been harnessed to advance the development of oral nanomedicine.

Stomach engineering: region-specific characterization of the decellularized porcine stomach

PURPOSE

Patients affected by microgastria, severe gastroesophageal reflux, or those who have undergone subtotal gastrectomy, have commonly described reporting dumping syndromes or other symptoms that seriously impair the quality of their life. Gastric tissue engineering may offer an alternative approach to treating these pathologies. Decellularization protocols have great potential to generate novel biomaterials for large gastric defect repair. There is an urgency to define more reliable protocols to foster clinical applications of tissue-engineered decellularized gastric grafts.

METHODS

In this work, we investigated the biochemical and mechanical properties of decellularized porcine stomach tissue compared to its native counterpart. Histological and immunofluorescence analyses were performed to screen the quality of decellularized samples. Quantitative analysis was also performed to assess extracellular matrix composition. At last, we investigated the mechanical properties and cytocompatibility of the decellularized tissue compared to the native.

RESULTS

The optimized decellularization protocol produced efficient cell removal, highlighted in the absence of native cellular nuclei. Decellularized scaffolds preserved collagen and elastin contents, with partial loss of sulfated glycosaminoglycans. Decellularized gastric tissue revealed increased elastic modulus and strain at break during mechanical tensile tests, while ultimate tensile strength was significantly reduced. HepG2 cells were seeded on the ECM, revealing matrix cytocompatibility and the ability to support cell proliferation.

CONCLUSION

Our work reports the successful generation of acellular porcine gastric tissue able to support cell viability and proliferation of human cells.

Evaluation of the performance of the human gastric simulator using durum wheat-based foods of contrasting food structure

The selection of gastric digestion parameters in food digestion studies using in vitro models is critical to properly represent structural changes in the stomach. This study aimed to evaluate the performance of digestion in the human gastric simulator (HGS) using generalized in vitro gastric digestion parameters (secretion rate of 4.1 mL min^-1, gastric emptying rate of 5.68 g min^-1) that were derived from a previous in vivo study using six starch-rich foods. Two of the six foods used in the in vivo study (cooked durum wheat porridge/semolina and pasta) were digested in the HGS for up to 240 min, then the properties of the emptied and remaining digesta were measured. The properties of the in vitro remaining digesta were compared to those measured in vivo (growing pig stomach). The trends in the gastric breakdown rate and mechanisms, dry matter emptying kinetics, and starch hydrolysis of pasta and semolina were similar to those of in vivo. Gastric breakdown and dilution kinetics in vitro and in vivo were well-related but did not have a 1 : 1 correlation, whereas gastric acidification kinetics in the HGS deviated from that observed in vivo. The results suggest that generalized digestion parameters could be used to predict the effect of food structure on in vivo gastric breakdown and emptying, but care should be taken in interpretation of results, as the gastric acidification process was different from what was observed in vivo. This information will help refine in vitro digestion model parameters to provide more physiologically-relevant data in future studies.

Anti-Oxidant and Anti-Inflammatory Effects of Astaxanthin on Gastrointestinal Diseases

A moderate amount of reactive oxygen species (ROS) is produced under normal conditions, where they play an important role in cell signaling and are involved in many aspects of the immune response to pathogens. On the other hand, the excessive production of ROS destructs macromolecules, cell membranes, and DNA, and activates pro-inflammatory signaling pathways, which may lead to various pathologic conditions. Gastrointestinal (GI) mucosa is constantly exposed to ROS due to the presence of bacteria and other infectious pathogens in food, as well as alcohol consumption, smoking, and the use of non-steroidal anti-inflammatory drugs (NSAID). Prolonged excessive oxidative stress and inflammation are two major risk factors for GI disorders such as ulcers and cancers. Bioactive food compounds with potent anti-oxidant and anti-inflammatory activity have been tested in experimental GI disease models to evaluate their therapeutic potential. Astaxanthin (AST) is a fat-soluble xanthophyll carotenoid that is naturally present in algae, yeast, salmon, shrimp, and krill. It has been shown that AST exhibits protective effects against GI diseases via multiple mechanisms. Residing at the surface and inside of cell membranes, AST directly neutralizes ROS and lipid peroxyl radicals, enhances the activity of anti-oxidant enzymes, and suppresses pro-inflammatory transcription factors and cytokines. In addition, AST has been shown to inhibit cancer cell growth and metastasis via modulating cell proliferation-related pathways, apoptosis, and autophagy. Considering the potential benefits of AST in GI diseases, this review paper aims to summarize recent advances in AST research, focusing on its anti-oxidant and anti-inflammatory effects against gastric and intestinal ulcers and cancers.

Gastrointestinal Digestion and Microbial Hydrolysis of Alkyl Gallates: Potential Sustained Release of Gallic Acid

Phenolipids such as alkyl gallates (A-GAs) have been approved by the food industry as non-toxic antioxidant additives, which are also regarded as an emerging source of functional food ingredients. However, comprehensive understanding of their digestive absorption is needed. Thus, the models of live mice and anaerobic fermentation were used to clarify the distribution and microbial hydrolysis characteristics of A-GAs in the gastrointestinal tract. HPLC-UV results demonstrated that A-GAs could be hydrolyzed by intestinal lipases and gut microorganisms including Lactobacillus to produce free gallic acid (GA). Through regulating the chain length of the lipid part in A-GAs, the sustained and controllable release of the GA can be easily achieved. Furthermore, A-GAs were also able to reach the colon and the cecum, which would lead to potential gastrointestinal protective effects. Therefore, A-GAs may be applied as possible ingredient for functional foods.

Comparative Study of the Gastric Mucosa of Risso's Dolphin (Grampus griseus) and Bottlenose Dolphin (Tursiops truncatus): A Key to Manage the Diet in Captive Conditions

To histologically evaluate the gastric compartments of Risso’s (Grampus griseus) and bottlenose dolphins (Tursiops truncatus) and provide suggestions for the diet of Risso’s dolphins in captivity, we examined 12 stomachs from both species. While slight differences in keratinization were observed in the forestomach, significant differences came to light in the second stomach’s mucosa. At this level, in Risso’s dolphin, the principal cells are markedly reduced in size and located externally to the parietal cells, not interspersed between them, compared to bottlenose dolphins; differences were also observed in the structure and concentration of the parietal and principal cells of the gastric body glands (p < 0.0001). The quantitative results of G- and D-cell counts in the gastric mucosa show a clear difference, with a higher concentration of G cells in the mucosa of Risso’s dolphin (t = 7.334; p < 0.0001) and a higher level of D cells in bottlenose dolphin mucosa (t = 3.123; p = 0.0049). These results suggest that parietal cells undergo greater stimulation by gastrin produced by G cells, with greater acid secretion in G. griseus. Further studies are needed to understand whether an inappropriate diet could lead to severe clinical signs due to gastric acidity in Risso’s dolphin.

Viscera Characteristics of MSTN-Edited Heterozygous Pigs

Myostatin (MSTN) is a protein that negatively regulates growth of skeletal muscle, and inactivation of MSTN improves the mass of skeletal muscle. Our previous work found that MSTN^+/− pigs have higher muscle depth and lower fat depth compared to wild type without any developmental problems. Therefore, MSTN-edited pigs are most likely to appear as heterozygotes in the potential future market, but the characteristics of organs in digestive and reproductive system of pigs with MSTN gene editing remains unclear. Here, we investigated the histological of the organs in the digestive system and reproductive system in MSTN gene heterozygotes at adult stages. The length of intestine was further compared between adult heterozygous and wild type pigs. We found no significant differences in histomorphology of organs, including heart, duodenum, jejunum, ileum, cecum, colon, testis, epididymis, ovaries, oviducts and uterus, between individuals from two genotypes. Moreover, there was no significant difference in the average length of intestine in adult pigs. Our data provide a reference for further clarifying the applications of MSTN gene edited pigs.

Review of paediatric gastrointestinal physiology relevant to the absorption of orally administered medicines

Despite much progress in regulations to improve paediatric drug development, there remains a significant need to develop better medications for children. For the design of oral dosage forms, a detailed understanding of the specific gastrointestinal (GI) conditions in children of different age categories and how they differ from GI conditions in adults is essential. Several review articles have been published addressing the ontogeny of GI characteristics, including luminal conditions in the GI tract of children. However, the data reported in most of these reviews are of limited quality because (1) information was cited from very old publications and sometimes low quality sources, (2) data gaps in the original data were filled with textbook knowledge, (3) data obtained on healthy and sick children were mixed, (4) average data obtained on groups of patients were mixed with data obtained on individual patients, and (5) results obtained using investigative techniques that may have altered the outcome of the respective studies were considered. Consequently, many of these reviews draw conclusions that may be incorrect. The aim of the present review was to provide a comprehensive and updated overview of the available original data on the ontogeny of GI luminal conditions relevant to oral drug absorption in the paediatric population. To this end, the PubMed and Web of Science metadatabases were searched for appropriate studies that examined age-related conditions in the oral cavity, esophagus, stomach, small intestine, and colon. Maturation was observed for several GI parameters, and corresponding data sets were identified for each paediatric age group. However, it also became clear that the ontogeny of several GI traits in the paediatric population is not yet known. The review article provides a robust and valuable data set for the development of paediatric in vitro and in silico biopharmaceutical tools to support the development of age-appropriate dosage forms. In addition, it provides important information on existing data gaps and should provide impetus for further systematic and well-designed in vivo studies on GI physiology in children of specific age groups in order to close existing knowledge gaps and to sustainably improve oral drug therapy in children.

In vitro models to evaluate ingestible devices: Present status and current trends

Orally ingestible medical devices offer significant opportunity in the diagnosis and treatment of gastrointestinal conditions. Their development necessitates the use of models that simulate the gastrointestinal environment on both a macro and micro scale. An evolution in scientific technology has enabled a wide range of in vitro, ex vivo and in vivo models to be developed that replicate the gastrointestinal tract. This review describes the landscape of the existing range of in vitro tools that are available to characterize ingestible devices. Models are presented with details on their benefits and limitations with regards to the evaluation of ingestible devices and examples of their use in the evaluation of such devices is presented where available. The multitude of models available provides a suite of tools that can be used in the evaluation of ingestible devices that should be selected on the functionality of the device and the mechanism of its function.

Gastroretentive Technologies in Tandem with Controlled-Release Strategies: A Potent Answer to Oral Drug Bioavailability and Patient Compliance Implications

There have been many efforts to improve oral drug bioavailability and therapeutic efficacy and patient compliance. A variety of controlled-release oral delivery systems have been developed to meet these needs. Gastroretentive drug delivery technologies have the potential to achieve retention of the dosage form in the upper gastrointestinal tract (GIT) that can be sufficient to ensure complete solubilisation of the drugs in the stomach fluids, followed by subsequent absorption in the stomach or proximal small intestine. This can be beneficial for drugs that have an “absorption window” or are absorbed to a different extent in various segments of the GIT. Therefore, gastroretentive technologies in tandem with controlled-release strategies could enhance both the therapeutic efficacy of many drugs and improve patient compliance through a reduction in dosing frequency. The paper reviews different gastroretentive drug delivery technologies and controlled-release strategies that can be combined and summarises examples of formulations currently in clinical development and commercially available gastroretentive controlled-release products. The different parameters that need to be considered and monitored during formulation development for these pharmaceutical applications are highlighted.

Surgical Treatment for Gastric Cancer

Surgery is an essential component of curative-intent treatment strategies for gastric cancer. However, the care of each patient with gastric cancer must be individualized based on patient and tumor characteristics. It is important that all physicians who will be caring for patient with gastric cancer understand the current best practices of surgical management to provide patients with the highest quality of care. This article aims to provide this information while acknowledging areas of surgical management that are still controversial.

Radiological Anatomy of Stomach and Duodenum with Clinical Significance

Anatomy is the key to accurate imaging interpretation. It is essential for radiologists to thoroughly understand the normal anatomy and spatial relationships of the stomach and duodenum to accurately localize the site of abnormality. In this article, we describe in detail the gross and applied radiological anatomy of the stomach and duodenum, and the current role of various radiological investigations (including barium studies, endoscopic ultrasonography, computed tomography, and magnetic resonance imaging) in the evaluation of the diseases involving the stomach and duodenum.

Tracking physical breakdown of rice- and wheat-based foods with varying structures during gastric digestion and its influence on gastric emptying in a growing pig model

There is currently a limited understanding of the effect of food structure on physical breakdown and gastric emptying of solid starch-based foods during gastric digestion. Moisture uptake, pH, particle size, rheological, and textural properties of six solid starch-based diets from different sources (Durum wheat and high amylose white rice) and of different macrostructures (porridge, native grain, agglomerate/couscous, and noodle) were monitored during 240 min of gastric digestion in a growing pig model. Changes in the physical properties of the gastric digesta were attributed to the influence of gastric secretions and gastric emptying, which were both dependent on the buffering capacity and initial macrostructure of the diets. Differences between the proximal and distal stomach regions were found in the intragastric pH and texture of the gastric digesta. For example, rice couscous, which had the smallest particle size and highest buffering capacity among the rice-based diets, had the shortest gastric emptying half-time and no significant differences between proximal and distal stomach digesta physical properties. Additionally, a relationship between gastric breakdown rate, expressed as gastric softening half-time from texture analysis, and gastric emptying half-time of dry matter was also observed. These findings provide new insights into the breakdown processes of starch-based solid foods in the stomach, which can be beneficial for the development of food structures with controlled rates of breakdown and gastric emptying during digestion.

Structural breakdown of starch-based foods during gastric digestion and its link to glycemic response: In vivo and in vitro considerations

The digestion of starch-based foods in the small intestine as well as factors affecting their digestibility have been previously investigated and reviewed in detail. Starch digestibility has been studied both in vivo and in vitro, with increasing interest in the use of in vitro models. Although previous in vivo studies have indicated the effect of mastication and gastric digestion on the digestibility of solid starch-based foods, the physical breakdown of starch-based foods prior to small intestinal digestion is often less considered. Moreover, gastric digestion has received little attention in the attempt to understand the digestion of solid starch-based foods in the digestive tract. In this review, the physical breakdown of starch-based foods in the mouth and stomach, the quantification of these breakdown processes, and their links to physiological outcomes, such as gastric emptying and glycemic response, are discussed. In addition, the physical breakdown aspects related to gastric digestion that need to be considered when developing in vitro-in vivo correlation in starch digestion studies are discussed. The discussion demonstrates that physical breakdown prior to small intestinal digestion, especially during gastric digestion, should not be neglected in understanding the digestion of solid starch-based foods.

Effect of deglycosylation on immunoreactivity and in vitro pepsin digestibility of major cashew (Anacardium occidentale L.) allergen, Ana o 1

Major cashew allergen, Ana o 1, was purified in its native form from cashew seeds and subjected to enzymatic deglycosylation using PNGase F to assess the potential role of N-glycans in immunoreactivity. Western and dot blotting with pooled human plasma containing anticashew IgE revealed that deglycosylation increased IgE-binding of Ana o 1. Removal of N-glycans may have exposed previously masked Ana o 1 epitopes. Purified glycosylated and deglycosylated Ana o 1 were also subjected to in vitro pepsin digestion at pH 3.0 for 2 hr. Both glycosylated and deglycosylated Ana o 1 remained stable and reactive with IgE antibodies following digestion. PRACTICAL APPLICATION: Understanding the role of glycosylation in Ana o 1 immunoreactivity may provide insight into the potential development of hypoallergenic cashews/cashew products for sensitive individuals in the future.

Biomechanical Investigation of the Stomach Following Different Bariatric Surgery Approaches

Background: The stomach is a hollow organ of the gastrointestinal tract, on which bariatric surgery (BS) is performed for the treatment of obesity. Even though BS is the most effective treatment for severe obesity, drawbacks and complications are still present because the intervention design is largely based on the surgeon’s expertise and intraoperative decisions. Bioengineering methods can be exploited to develop computational tools for more rational presurgical design and planning of the intervention. Methods: A computational mechanical model of the stomach was developed, considering the actual complexity of the biological structure, as the nonhomogeneous and multilayered configuration of the gastric wall. Mechanical behavior was characterized by means of an anisotropic visco-hyperelastic constitutive formulation of fiber-reinforced conformation, nonlinear elastic response, and time-dependent behavior, which assume the typical features of gastric wall mechanics. Model applications allowed for an analysis of the influence of BS techniques on stomach mechanical functionality through different computational analyses. Results: Computational results showed that laparoscopic sleeve gastrectomy and endoscopic sleeve gastroplasty drastically alter stomach capacity and stiffness, while laparoscopic adjustable gastric banding modestly affects stomach stiffness and capacity. Moreover, the mean elongation strain values, which are correlated to the mechanical stimulation of gastric receptors, were elevated in laparoscopic adjustable gastric banding compared to other procedures. Conclusions: The investigation of stomach mechanical response through computational models provides information on different topics such as stomach capacity and stiffness and the mechanical stimulation of gastric receptors, which interact with the brain to control satiety. These data can provide reliable support to surgeons in the presurgical decision-making process.

Non-Tuberculous Mycobacteria Interference with BCG-Current Controversies and Future Directions

The global tuberculosis (TB) epidemic caused by the bacterial pathogen Mycobacterium tuberculosis (M.tb) continues unabated. The Mycobacterium bovis bacillus Calmette–Guérin (BCG) vaccination is widely utilized worldwide to protect against infection with M.tb. BCG vaccine protection against TB has had widely varying results for reasons that are not well understood. BCG vaccine interference by non-tuberculosis (NTM) mycobacterial species has been implicated as the potential cause of reduced BCG vaccine efficacy against M.tb. Ongoing efforts to develop new vaccines for TB requires a thorough understanding of the effect of NTM exposure on BCG vaccine efficacy, which may ultimately be a critical determinant of success. We reviewed the conflicting reports on whether NTM interferes with the BCG vaccine, potential explanations to help resolve the controversy, and strategies for developing better animal models. Further studies are needed to longitudinally track the effects of NTM exposure on BCG vaccine-induced host-protective anti-TB immunity.

An agent-based simulator for the gastrointestinal pathway of Listeria monocytogenes

We developed an agent-based gastric simulator for a human host to illustrate the within host survival mechanisms of Listeria monocytogenes. The simulator incorporates the gastric physiology and digestion processes that are critical for pathogen survival in the stomach. Mathematical formulations for the pH dynamics, stomach emptying time, and survival probability in the presence of gastric acid are integrated in the simulator to evaluate the portion of ingested bacteria that survives in the stomach and reaches the small intestine. The parameters are estimated using in vitro data relevant to the human stomach and L. monocytogenes. The simulator predicts that 5%-29% of ingested bacteria can survive a human stomach and reach the small intestine. In the absence of extensive scientific experiments, which are not feasible on the grounds of ethical and safety concerns, this simulator may provide a supplementary tool to evaluate pathogen survival and subsequent infection, especially with regards to the ingestion of small doses.

A Multi-Gene Model Effectively Predicts the Overall Prognosis of Stomach Adenocarcinomas With Large Genetic Heterogeneity Using Somatic Mutation Features

Background

Stomach adenocarcinoma (STAD) is one of the most common malignancies worldwide with poor prognosis. It remains unclear whether the prognosis is associated with somatic gene mutations.

Methods

In this research, we collected two independent STAD cohorts with both genetic profiling and clinical follow-up data, systematically investigated the association between the prognosis and somatic mutations, and analyzed the influence of heterogeneity on the prognosis-genetics association.

Results

Typical association was identified between somatic mutations and overall prognosis for individual cohorts. In The Cancer Genome Atlas (TCGA) cohort, a list of 24 genes was also identified that tended to mutate within cases of the poorest prognosis. The association showed apparent heterogeneity between different cohorts, although common signatures could be identified. A machine-learning model was trained with 20 common genes that showed a similar mutation rate difference between prognostic groups in the two cohorts, and it classified the cases in each cohort into two groups with significantly different prognosis. The model outperformed both single-gene models and TNM-based staging system significantly.

Conclusion

The study made a systematic analysis on the association between STAD prognosis and somatic mutations, identified signature genes that showed mutation preference in different prognostic groups, and developed an effective multi-gene model that can effectively predict the overall prognosis of STAD in different cohorts.

Effects of transport stress on pathological injury and expression of main heat shock proteins in the caprine stomach

Background

Transportation is necessary to introduce new breeds of goats to the farm and move the adult meat goat from the farm to the slaughterhouse. However, these actions may give rise to transport stress. Heat shock proteins (HSPs) are playing some important regulate roles during transport stress. The aim of this study was to evaluate the effects of transport stress on the pathological injury and HSPs expression in the stomach of goats. A total of three batches of Ganxi goats from western Jiangxi province were enrolled in this study. For each batch, twelve healthy adult male goats were randomly divided into three groups (four goats per batch and per group): Control group, stress group transported during 2 h and stress group transported during 6 h.

Results

Our results showed that the different degrees of stomach walls damage, with the change of expression levels of heat shock protein 27 (HSP27), heat shock protein 70 (HSP70) and heat shock protein 90 (HSP90), occurred after goats transportation. In rumen, the mRNA and protein expressions of HSP27 and HSP70 were increased after transport stress, but not HSP90. In reticulum, all three HSPs mRNA and protein levels were upregulated after 2 h transport, but decreased after 6 h transport. In omasum, HSP27 and HSP70 mRNA and protein were increased after transport stress, however, HSP90 mRNA level only had a slightly enhancement after transport stress. In abomasum, HSP70 and HSP90 mRNA and protein levels were increased after transport stress, but HSP27 was decreased after transport stress.

Conclusions

Taken together, these results revealed that the pathological changes in the gastric tissues and the stomach HSPs expression in goats are related to transport stress and duration. Moreover, this study also provides some new data to advocate reducing transport stress of goats and improving animal welfare.

Loss of stomach, loss of appetite? Sequencing of the ballan wrasse (Labrus bergylta) genome and intestinal transcriptomic profiling illuminate the evolution of loss of stomach function in fish

BACKGROUND

The ballan wrasse (Labrus bergylta) belongs to a large teleost family containing more than 600 species showing several unique evolutionary traits such as lack of stomach and hermaphroditism. Agastric fish are found throughout the teleost phylogeny, in quite diverse and unrelated lineages, indicating stomach loss has occurred independently multiple times in the course of evolution. By assembling the ballan wrasse genome and transcriptome we aimed to determine the genetic basis for its digestive system function and appetite regulation. Among other, this knowledge will aid the formulation of aquaculture diets that meet the nutritional needs of agastric species.

RESULTS

Long and short read sequencing technologies were combined to generate a ballan wrasse genome of 805 Mbp. Analysis of the genome and transcriptome assemblies confirmed the absence of genes that code for proteins involved in gastric function. The gene coding for the appetite stimulating protein ghrelin was also absent in wrasse. Gene synteny mapping identified several appetite-controlling genes and their paralogs previously undescribed in fish. Transcriptome profiling along the length of the intestine found a declining expression gradient from the anterior to the posterior, and a distinct expression profile in the hind gut.

CONCLUSIONS

We showed gene loss has occurred for all known genes related to stomach function in the ballan wrasse, while the remaining functions of the digestive tract appear intact. The results also show appetite control in ballan wrasse has undergone substantial changes. The loss of ghrelin suggests that other genes, such as motilin, may play a ghrelin like role. The wrasse genome offers novel insight in to the evolutionary traits of this large family. As the stomach plays a major role in protein digestion, the lack of genes related to stomach digestion in wrasse suggests it requires formulated diets with higher levels of readily digestible protein than those for gastric species.

Gastric cancer with lesion extending to spleen and perforation into free peritoneum

Perforated gastric carcinoma is a rare condition that is hard to diagnose preoperatively. It is associated with advanced cancer stages and has a high mortality, particularly in cases presenting preoperative shock. Few studies have investigated the presentation and adequate management of these carcinomas. In addition, there are no reports in the literature on perforations extending to the spleen, as described in this case, making the management of these lesions challenging. Our article reports a case of gastric tumor perforation extending to the spleen, which presented as a perforated acute abdomen. The patient was treated with total gastrectomy and D2 lymph node resection with splenectomy and progressed well with current survival of one year at disease stage IV.

Nanoparticles for oral delivery: Design, evaluation and state-of-the-art

The oral route is a preferred method of drug administration, though achieving effective drug delivery and minimizing off-target side effects is often challenging. Formulation into nanoparticles can improve drug stability in the harsh gastrointestinal (GI) tract environment, providing opportunities for targeting specific sites in the GI tract, increasing drug solubility and bioavailability, and providing sustained release in the GI tract. However, the unique and diverse physiology throughout the GI tract, including wide variation in pH, mucus that varies in thickness and structure, numerous cell types, and various physiological functions are both a barrier to effective delivery and an opportunity for nanoparticle design. Here, nanoparticle design aspects to improve delivery to particular sites in the GI tract are discussed. We then review new methods for evaluating oral nanoparticle formulations, including a short commentary on data interpretation and translation. Finally, the state-of-the-art in preclinical targeted nanoparticle design is reviewed.

Emphysematous gastritis and gastric emphysema: similar radiographic findings, distinct clinical entities

INTRODUCTION

Despite similar appearances on imaging studies, emphysematous gastritis (EG) and gastric emphysema (GE) are rare clinical entities encountered in surgical practices. The purpose of this review is to clarify the presentation, natural history, and optimal treatment strategies for these two disorders.

METHODS

We conducted a comprehensive literature review for reported adult cases of EG and GE in MEDLINE. Two cases from our institution were also included. Patient with demographics, diagnostic and therapeutic data, and outcomes were compared between patients with EG and GE.

RESULTS

A total of 75 cases were included for our review. The finding of intramural air in the stomach was often associated with portal vein gas, pneumatosis intestinalis, or pneumoperitoneum in both groups. Surgical removal of the stomach was performed in 23.1% of EG patients, but only one patient in the GE group. In the EG group, overall mortality (55%) appeared to be driven by sepsis and its complications, whereas in the GE group, mortality (29%) was attributable to comorbid conditions and the underlying illness.

CONCLUSIONS

Prompt surgical intervention is more commonly indicated for severe EG and is directed at removal of the septic organ, while the primary indication for surgical intervention in GE is the uncertainty of the diagnosis.

The gastric fluid proteome as a potential source of gastric cancer biomarkers

Gastric cancer is a significant cause of death in many parts of the world. Although timely intervention is associated with better clinical outcome, early gastric cancer detection is frequently not possible given its asymptomatic nature. As such, sensitive and specific gastric cancer biomarkers are highly sought after as diagnostic surrogates that may replace invasive endoscopic and histological examinations. Unlike gastric cancer tissue and serum which are heterogeneous and overloaded with abundant proteins, the gastric fluid contains a concentrated molecular biopsy of the stomach that accurately reflects gastric oncology. This review attempts to (i) summarise the state of proteomics-based gastric cancer biomarker discovery from patient gastric fluids, (ii) outline key considerations in working with the body fluid, and (ii) discuss how the challenges in gastric cancer diagnosis may be overcome with new perspectives in gastric cancer screening.

Antral recirculation in the stomach during gastric mixing

We investigate flow in the stomach during gastric mixing using a numerical simulation with an anatomically realistic geometry and free-surface flow modeling. Because of momentum differences between greater and lesser curvatures during peristaltic contractions, time-averaged recirculation is generated in the antrum, with retropulsive flow away from the pylorus and compensation flow along the greater curvature toward the pylorus. Gastric content in the distal stomach is continuously transported to the distal antrum by the forward flow of antral recirculation, and it is then mixed by the backward retropulsive flow. Hence, the content inside the antral recirculation is well mixed independently of initial location, whereas the content outside the recirculation is poorly mixed. Free-surface modeling enables us to analyze the effects of posture on gastric mixing. In the upright, prone, and right lateral positions, most of the antrum is filled with content, and the content is well mixed by antral recirculation. In contrast, in the supine and left lateral positions, most of the content is located outside antral recirculation, which results in poor mixing. The curved, twisted shape of the stomach substantially supports gastric mixing in fluid mechanical terms.

Gastrointestinal system

The functions of the gastrointestinal (GI) tract include digestion, absorption, excretion, and protection. In this review, we focus on the electrical activity of the stomach and small intestine, which underlies the motility of these organs, and where the most detailed systems descriptions and computational models have been based to date. Much of this discussion is also applicable to the rest of the GI tract. This review covers four major spatial scales: cell, tissue, organ, and torso, and discusses the methods of investigation and the challenges associated with each. We begin by describing the origin of the electrical activity in the interstitial cells of Cajal, and its spread to smooth muscle cells. The spread of electrical activity through the stomach and small intestine is then described, followed by the resultant electrical and magnetic activity that may be recorded on the body surface. A number of common and highly symptomatic GI conditions involve abnormal electrical and/or motor activity, which are often termed functional disorders. In the last section of this review we address approaches being used to characterize and diagnose abnormalities in the electrical activity and how these might be applied in the clinical setting. The understanding of electrophysiology and motility of the GI system remains a challenging field, and the review discusses how biophysically based mathematical models can help to bridge gaps in our current knowledge, through integration of otherwise separate concepts.

Latest results (12-21 years) of a prospective randomized study comparing Billroth II and Roux-en-Y anastomosis after a partial gastrectomy plus vagotomy in patients with duodenal ulcers

INTRODUCTION

After a partial resection of the stomach, the continuity of the gastrointestinal tract can be restored either by a Billroth II gastrojejunal anastomosis or a Roux-en-Y gastrojejunostomy. Each procedure has its advantages and disadvantages.

OBJECTIVE

To determine through a prospective and random clinical trial, the clinical outcome and the endoscopic and histologic alterations of the distal esophagus and the gastric remnant in patients who received a partial distal gastrectomy due to duodenal ulcers and a Billroth II or Roux-en-Y reconstruction.

MATERIAL AND METHODS

In this prospective random trial, a total of 75 patients with duodenal ulcers were included. A bilateral selective vagotomy and partial distal gastrectomy were performed in all patients. A Billroth II or Roux-en-Y 60-cm-long loop was randomly used for reconstruction of the gastrointestinal tract. During the latest follow-up clinical evaluation, upper endoscopy and biopsy samples from the distal esophagus and gastric remnant were obtained.

RESULTS

There was 1 operative mortality and 6 patients had some morbidity. The average follow-up period was 15.5 years (range, 11-21). Patients with Roux-en-Y gastrojejunostomy were significantly more asymptomatic and had greater Visick I grading than patients with Billroth II reconstruction (P < 0.001). In the distal esophagus, endoscopic findings were normal in 90% of the Roux-en-Y group, but only in 51% of the Billroth II group (P < 0.0009). Nearly 25% of the latter group had the appearance of a short-segment Barrett esophagus compared with 3% of the Roux-en-Y group (P < 0.0001). The gastric remnant endoscopic findings were normal in 100% of the Roux-en-Y group and in 18% of the Billroth II group (P < 0.02). Histologic analyses showed similar proportions of normal fundic mucosa and chronic active fundic gastritis. However, chronic atrophic fundic gastritis and intestinal metaplasia were significantly more frequent after Billroth II reconstruction (P < 0.008). Helicobacter pylorus was present in a similar proportion of patients.

CONCLUSIONS

This prospective and random study showed that Roux-en-Y gastrojejunostomy is significantly better than a Billroth II reconstruction in patients with duodenal ulcers, through subjective and objective endoscopic and histologic evaluations during the latest follow-up evaluation.

Evaluation of the Cynomolgus Monkey Stomach: Recommendations for Standard Sampling Procedures in Nonclinical Safety Studies

The cynomolgus macaque is the most commonly used nonhuman primate in nonclinical toxicity testing, but the macroscopic and microscopic anatomy of the stomach in the cynomolgus macaque is poorly described. To develop a reliable sampling method for histologic evaluation of the cynomolgus macaque stomach in regulatory toxicity studies, the stomachs of control animals were prospectively evaluated using an extensive sectioning pattern. The stomach of the cynomolgus macaque differs from that described for the human stomach and has a prominent fundus that lacks parietal cells. A description of the macroscopic and microscopic anatomy is presented along with a recommended sectioning pattern for nonclinical toxicity studies and discussion of species differences. A thorough understanding of normal anatomy and species comparisons are critical to interpretation of potential toxicity findings and assessment of risk in humans.

Cryptosporidium parvum, a potential cause of colic adenocarcinoma

Background

Cryptosporidiosis represents a major public health problem. This infection has been reported worldwide as a frequent cause of diarrhoea. Particularly, it remains a clinically significant opportunistic infection among immunocompromised patients, causing potentially life-threatening diarrhoea in HIV-infected persons. However, the understanding about different aspects of this infection such as invasion, transmission and pathogenesis is problematic. Additionally, it has been difficult to find suitable animal models for propagation of this parasite. Efforts are needed to develop reproducible animal models allowing both the routine passage of different species and approaching unclear aspects of Cryptosporidium infection, especially in the pathophysiology field.

Results

We developed a model using adult severe combined immunodeficiency (SCID) mice inoculated with Cryptosporidium parvum or Cryptosporidium muris while treated or not with Dexamethasone (Dex) in order to investigate divergences in prepatent period, oocyst shedding or clinical and histopathological manifestations. C. muris-infected mice showed high levels of oocysts excretion, whatever the chemical immunosuppression status. Pre-patent periods were 11 days and 9.7 days in average in Dex treated and untreated mice, respectively. Parasite infection was restricted to the stomach, and had a clear preferential colonization for fundic area in both groups. Among C. parvum-infected mice, Dex-treated SCID mice became chronic shedders with a prepatent period of 6.2 days in average. C. parvum-inoculated mice treated with Dex developed glandular cystic polyps with areas of intraepithelial neoplasia, and also with the presence of intramucosal adenocarcinoma.

Conclusion

For the first time C. parvum is associated with the formation of polyps and adenocarcinoma lesions in the gut of Dex-treated SCID mice. Additionally, we have developed a model to compare chronic muris and parvum cryptosporidiosis using SCID mice treated with corticoids. This reproducible model has facilitated the evaluation of clinical signs, oocyst shedding, location of the infection, pathogenicity, and histopathological changes in the gastrointestinal tract, indicating divergent effects of Dex according to Cryptosporidium species causing infection.

Helicobacter pylori gastritis, the unifying concept for gastric diseases

Helicobacter pylori infection causes a broad spectrum of clinical diseases and the clinical manifestations of the infection depend on host, environmental, and bacterial factors. These factors have an impact on the pattern and severity of gastritis and ultimately determine the clinical outcome of H. pylori infection. Better staging of gastritis may help to identify patients at risk of gastric cancer. In this article we will examine the complex interaction between host, environmental, and bacterial factors in the pathogenesis of H. pylori infection.

The effect of gastric digestion on food allergy

PURPOSE OF REVIEW

The role of the stomach as the primary location of protein digestion is very well recognized, leading to classification of proteins as digestion-resistant or digestion-labile. This review analyses the role of gastric digestion in food allergy.

RECENT FINDINGS

Hindrance of gastric digestion by elevation of the gastric pH, the therapeutic goal of anti-ulcer medication, was recently shown to trigger food allergy via oral sensitization in a murine food allergy model. The relevance in humans was assessed in an observational study of 152 gastroenterological patients who were medicated with anti-ulcer drugs due to dyspeptic disorders. Twenty-five percent of all patients developed a boost or de-novo IgE formation towards regular constituents of the daily diet. The clinical relevance of the induced antibodies was confirmed by positive skin and oral-provocation tests. Moreover, the importance of gastric digestion was also proven for food-allergic patients, as the allergenicity of allergens were reduced up to a 10,000-fold by gastric digestion.

SUMMARY

These recent studies indicate for the first time the important gate-keeping function of gastric digestion, both in the sensitization and the effector phases of food allergy.