Regions Of Gastrointestinal Tract Research Articles

Electronic‐Free Traceable Smart Capsule for Gastrointestinal Microbiome Sampling

AbstractNon‐invasive smart electronic‐free sampling capsules have revolutionized the exploration of microbiome‐disease interactions in inaccessible regions of the gastrointestinal (GI) tract. However, a significant impediment to the broader use of electronic‐free capsules is the challenge of reliably tracking and determining their in vivo location. Variability in patient motility introduces uncertainties in capsule position. Thus, there is a critical need for effective solutions that ensure traceability in microbiome studies employing such capsules. While tracking methods are explored in previous smart ingestible capsule designs, most have relied on RF, imaging, and radiation‐based techniques, limiting sampling volume, increasing costs, complicating design, and raising health concerns due to ionizing radiation exposure. To address these challenges, the design of an electronic‐free smart capsule is introduced that integrates a metal tracer for easy metal detection, serving as a reliable tracking mechanism. The capsule is housed in a 3D‐printed casing and includes a superabsorbent hydrogel serving as both a sampling medium and an actuator within the capsule. The capsule's targeted sampling of the GI tract is accomplished by covering the capsule's sampling port with a pH‐responsive coating. Optimal dimensions and material for the cylindrical shaped metal tracer on the capsule are determined through extensive optimizations, considering factors such as gastric flotation, corrosion resistance, read distance, and omnidirectional detectability. The results of these investigations reveal that a 12 mm stainless steel (SS 316L) cylinder offers the necessary detection and tracing capabilities with minimal toxicity and excellent corrosion resistance under relevant physiological conditions in the GI tract. Validation studies, both in vitro and in vivo, confirmed the capsule's trackability using a handheld metal detector. These findings are further validated by X‐ray imaging and CT scans, demonstrating the metal detector's ability to distinguish approximate GI tract regions and determine the time point of excretion. This innovative approach provides a reliable and cost‐effective solution for tracking electronic‐free smart capsules, enhancing their applicability in microbiome research for both human and animal studies.

Localization of alpha 2,6-linked sialic acid residues in gastrointestinal tract compartments of some tetrapod’s representatives: Comparative histochemical study

Epithelial mucins composed mainly of glycoproteins and play a vital role as protective barrier against a variety of harmful molecules and microbial infection. Additionally sialic acids, like glycoproteins, are considered as a main component of epithelial mucins and play an important role in mucosal immunity. For example, alpha 2,6-linked galactose/N-acetyl-galactosamine (Gal/GalNAc) sialic acid residues can recognize and mask different biological sites in some intermolecular or intercellular interactions. In this study, the localization sites relationship between general mucins and alpha 2,6-linked Gal/GalNAc sialic acid residues in different compartments in gastrointestinal tract (GIT) of tetrapod representatives were investigated using lectin histochemistry. The toad (Bufo regularis), lizard (Trachylepis quinquetaeniata), pigeon (Columba livia domestica) and mouse (Mus musculus) were used as amphibian, reptilian, avian and mammalian representatives respectively. In general, the biodistribution sites of mucins are localized in most compartment sites and partially overlapped with the sites of sialic acid residues in some compartment in each animal representative. Additionally, the localization sites of both mucins and sialic acid in the GIT regions differ based on the tissue type in each tetrapod representative. The mucosa of oesophagus in the toad and lizard showed higher positive signal of general mucins compared with other tetrapod representatives. However, the mucosa of the oesophagus in the toad revealed a positive signal of sialic acid in the tubular glands only, whereas the lizard’s mucosa showed a positive signal of sialic acid in the goblet cells. Additionally, the pigeon’s oesophagus showed no localization of the sialic acid or mucins while, all layers of the mouse’s oesophagus showed a positive localization of the sialic acid residues. In the stomach, all stomach mucosa compartments in all representatives showed positive signal of mucins, while the gastric glands in the toad, pigeon (proventricular glands) and mouse showed signals of sialic acid residues localization but in different trends. While the lizard showed a localization of the sialic acid in the mucosal lamina propria only. Furthermore, the mucosa of the ileum showed positive signal of mucin in the goblet cells and some absorptive cells brush borders in all tetrapod animals. While a higher signal of the sialic acid residues in the absorptive cells but not the goblet cells in the case of the toad and mouse. While the lizard’s ileum showed a higher localization of sialic acid in the goblet cells only. Mucin localization in the rectum was similar to those in ileum. Specifically, the toad and lizard showed signals of the sialic acid residues in the goblet cells only, while the mouse’s rectum showed a higher signal of sialic acids in the absorptive cells and lamina propria but not in the goblet cells. The present study introduces important data about the biodistribution and localization profiles of general mucins and sialic acids residues in the GIT different compartments in each representative of tetrapoda animals. Further studies are needed to investigate the important role of sialic acid residues localization in different compartments of GIT mucosa.

The gastrointestinal microbiome in dairy cattle is constrained by the deterministic driver of the region and the modified effect of diet

BackgroundDairy cattle (Bos taurus), especially Holstein cows, which are the highest-producing dairy animals and are widely bred to provide milk products to humans, rely critically on their associated gastrointestinal tract (GIT) microbiota to digest plant feed. However, the region-specific taxonomic composition and function of the GIT microbiome in dairy cattle and the mechanistic basis for the diet-induced effects remain to be elucidated. ResultsWe collected 120 digesta samples from 10 GIT regions of 12 Holstein cows fed forage- and grain-based diets and characterized their GIT microbiome via functional shotgun metagenomics and the resolution of metagenome-assembled genomes. Our results demonstrated that the GIT microbiome was mainly partitioned into three distinct clusters, four-chambered stomach, small intestine, and large intestine. Moreover, we found that the four-chambered stomach microbiome with the highest diversity had a strong ability to degrade recalcitrant polysaccharide substrates, underpinned by the prevalence of potential cellulosome-­producing and plant-derived polysaccharide utilization loci-encoding consortia. In contrast, the post-gastric intestinal microbiome orchestrated alternative fermentation pathways to adapt to nutrient availability and energy acquisition. Diet shifts selectively modified the metabolic cascades of the microbiome in specific GIT regions, evidenced by the loss of fiber-degrading taxa and increased hydrogen sinks in propionate after grain introduction.ConclusionsOur findings provide new insights into GIT microbial organization and function in dairy cattle by GIT regions and diet regimes, which offers clues for improving animal production and health in the future.4ZJAH2fLvvvrZAThHy4aExVideo

Integrated multi-omics of the gastrointestinal microbiome and ruminant host reveals metabolic adaptation underlying early life development

BackgroundThe gastrointestinal tract (GIT) microbiome of ruminants and its metabolic repercussions vastly influence host metabolism and growth. However, a complete understanding of the bidirectional interactions that occur across the host-microbiome axis remains elusive, particularly during the critical development stages at early life. Here, we present an integrative multi-omics approach that simultaneously resolved the taxonomic and functional attributes of microbiota from five GIT regions as well as the metabolic features of the liver, muscle, urine, and serum in sika deer (Cervus nippon) across three key early life stages.ResultsWithin the host, analysis of metabolites over time in serum, urine, and muscle (longissimus lumborum) showed that changes in the fatty acid profile were concurrent with gains in body weight. Additional host transcriptomic and metabolomic analysis revealed that fatty acid β-oxidation and metabolism of tryptophan and branched chain amino acids play important roles in regulating hepatic metabolism. Across the varying regions of the GIT, we demonstrated that a complex and variable community of bacteria, viruses, and archaea colonized the GIT soon after birth, whereas microbial succession was driven by the cooperative networks of hub populations. Furthermore, GIT volatile fatty acid concentrations were marked by increased microbial metabolic pathway abundances linked to mannose (rumen) and amino acids (colon) metabolism. Significant functional shifts were also revealed across varying GIT tissues, which were dominated by host fatty acid metabolism associated with reactive oxygen species in the rumen epithelium, and the intensive immune response in both small and large intestine. Finally, we reveal a possible contributing role of necroptosis and apoptosis in enhancing ileum and colon epithelium development, respectively.ConclusionsOur findings provide a comprehensive view for the involved mechanisms in the context of GIT microbiome and ruminant metabolic growth at early life.5sdAQaaw9Xaw7sGvUGm-9aVideo

Exploring the potential for an evolutionarily conserved role of the taste 1 receptor gene family in gut sensing mechanisms of fish.

In this study, we investigated the transcriptional spatio-temporal dynamics of the taste 1 receptor (T1R) gene family repertoire in seabream (Sparus aurata [sa]), during larval ontogeny and in adult tissues. In early larval development, saT1R expression arises heterochronously, i.e. the extraoral taste-related perception in the gastrointestinal tract (GIT) anticipates first exogenous feeding (at 9 days post hatching [dph]), followed by the buccal/intraoral perception from 14 dph onwards, supporting the hypothesis that the early onset of the molecular machinery underlying saT1R expression in the GIT is not induced by food but rather genetically hardwired. During adulthood, we characterized the expression patterns of saT1R within specific tissues (n = 4) distributed in oropharingeal, GIT and brain regions substantiating their functional versatility as chemosensory signaling players to a variety of biological functions beyond oral taste sensation. Further, we provided for the first time direct evidences in fish for mRNA co-expression of a subset of saT1R genes (mostly saT1R3, i.e. the common subunit of the heterodimeric T1R complexes for the detection of “sweet” and “umami” substances), with the selected gut peptides ghrelin (ghr), cholecystokinin (cck), hormone peptide yy (pyy) and proglucagon (pg). Each peptide defines the enteroendocrine cells (ECCs) identity, and establishes on morphological basis, a direct link for T1R chemosensing in the regulation of fish digestive processes. Finally, we analyzed the spatial gene expression patterns of 2 taste signaling components functionally homologous to the mammalian G(i)α subunit gustducin, namely saG(i)α1 and saG(i)α2, and demonstrated their co-localization with the saT1R3 in EECs, thus validating their direct involvement in taste-like transduction mechanisms of the fish GIT. In conclusion, data provide new insights in the evolutionary conservation of gut sensing in fish suggesting a conserved role for nutrient sensors modulating entero-endocrine secretion.

Characterization of the Microbial Communities along the Gastrointestinal Tract in Crossbred Cattle.

Simple SummaryCrossbreeding has been used worldwide to improve milk production, milk composition, and reproduction performance. Understanding the structure of the microbial communities in the gastrointestinal tract (GIT) of crossbred cattle is paramount for developing new livestock management technologies with an emphasis on nutrition and sustainability. In this study, we investigated the gastrointestinal microbiota of Simmental × Holstein crossbred cattle using 16s rRNA gene sequencing. Microbial communities in the small intestine had the lowest diversity of bacteria and highest diversity of bacterial functions, and three groups of GIT regions, including the stomach, small intestine, and large intestine were characterized by specific bacteria and bacterial functions. In summary, spatial heterogeneity of the microbiota was found across the GIT of crossbreeds, and specific microbial biomarkers were identified in different regions.The gastrointestinal microbiota greatly affects the health status and production performance of bovines. Presently, many studies have used high-throughput sequencing methods to investigate the gastrointestinal microbiome in bovines. However, the microbiome profile of crossbred cattle across the whole gastrointestinal tract (GIT) has not been thoroughly reported. In this study, the digesta at ten regions (including the rumen, reticulum, omasum, abomasum, duodenum, jejunum, ileum, cecum, colon, and rectum) of the GIT were collected in three Simmental × Holstein crossbred heifers aged 17 months, and microbial DNA was extracted and amplified for sequencing of the V3–V4 regions of the 16S rRNA gene. Functional orthologs of the microbiota genome were predicted and analyzed. We found that samples were categorized into three groups (the stomach, small intestine, and large intestine) by principal coordinate analysis (PCoA) based on Bray–Curtis dissimilarity in both the bacterial composition and functional profile. Samples from small intestine had the lowest alpha diversity of bacteria composition and highest alpha diversity of the functional composition. Three groups of GIT regions were characterized by several microbiome features. The stomach was characterized by Bacteroidetes and Fibrobacteres at the phylum level, and KEGG pathways related to the metabolism of cofactors and vitamins, glycan biosynthesis, and metabolism were enriched in the stomach. The small intestine was characterized by Actinobacteria and Patescibacteria at the phylum level, and KEGG pathways related to xenobiotics biodegradation and metabolism were enriched in the small intestine. The large intestine featured Ruminococcaceae, Rikenellaceae, and Bacteroidacea at the family level, and KEGG pathways, including steroid hormone biosynthesis, linoleic acid metabolism, and cysteine and methionine metabolism were enriched in the large intestine. The results of the current study revealed the spatial heterogeneity of microbiota across the GIT in Simmental × Holstein crossbreeds and identified microbial biomarkers of different regions. The results can provide useful information for the study of the gastrointestinal microbiome in bovines.

A233 CHARACTERIZATION OF THE DUODENAL MICROBIOME IN PEDIATRIC CELIAC AND INFLAMMATORY BOWEL DISEASE PATIENTS

BackgroundBoth Celiac disease (CE) and inflammatory bowel disease (IBD) are lifelong gastrointestinal tract (GIT) disorders. CE is an autoimmune disorder triggered by gluten consumption and can result in small intestine villus atrophy, crypt hyperplasia and epithelial permeability, while IBD is characterized by chronic, reoccurring inflammation and ulcers in the GIT. There is increasing evidence linking GIT microbes to both CE and IBD pathogenesis. Studies have also shown that CE patients are at increased risk of developing IBD, suggesting a possible link between these diseases. The duodenum can be affected in both CE and IBD, but it is understudied as compared to other GIT regions.AimsWe thus aimed to characterize the duodenal microbiome of pediatric CE, IBD and control patients (n=76, 48 and 57 respectively) and hypothesized that the composition of microbes would vary between each diagnostic group.MethodsWe used mucosal luminal interface aspirates collected during upper endoscopy at the Children’s Hospital of Eastern Ontario. Metagenomic DNA was extracted from these samples and bacterial taxa was characterized by sequencing the V6 hypervariable region of the 16S rRNA gene.ResultsControl, CE, and IBD duodenal microbiotas showed no apparent differences in either α-diversity or β-diversity. However, we identified several significant differences between the relative abundances of specific taxa in these three patient groups. In particular, Atopobium parvulum was found to be enriched in Crohn’s disease samples when compared to non-IBD controls. There was also a trend for higher Bacteroides, Lactobacillus, Parabacteroides and Staphylococcus in CE patient MLI aspirates. These results are similar to what has been previously reported in CE patients. Finally, trends found in the duodenal MLI aspirates are more consistent with results previously found in the salivary microbiome in CD patients as opposed to studies of the large intestine.ConclusionsThis work provides unique insight into the microbial composition at the duodenum; a GIT region that has not been fully characterized in CE or IBD.Funding AgenciesCIHRGenome Canada

Primary Extranodal Lymphomas: A Five Year Retrospective Study from a Tertiary Care Cancer Centre, Kerala, India

Introduction: Primary Extranodal Lymphomas (pENLs) are defined as lymphomas with dominant extranodal involvement with no or minor involvement of lymph nodes after routine staging procedures. The present study highlights the profile of pENLs in Kerala, South India which is not yet reported in literature. Aim: To study the frequency, distribution and histopathology profile of pENLs diagnosed in a tertiary care cancer centre. Materials and Methods: This was a cross-sectional study done in a tertiary care cancer centre in Kerala, Southern India for a period of five years. All the cases of pENLs diagnosed during this five year period which fulfilled the inclusion criteria were included in this study. These 3,357 cases were reviewed and classified according to the 2017 revised 4th edition World Health Organisation (WHO) classification of Tumours of Haematopoietic and Lymphoid tissues. Data was summarised using descriptive statistics. The frequency, distribution and histopathology features of pENLs were studied. Results: A total number of 3,357 lymphomas were diagnosed at the centre during this period. Non Hodgkin lymphomas (NHLs) constituted 2610 (78%). pENLs constituted 477 cases which included two cases of classical hodgkin lymphomas. Primary extranodal NHL (n=475) constituted 18.2% of NHL. Diffuse large B-cell lymphoma, Not Otherwise Specified (NOS), (DLBCL, NOS) was the most common histologic subtype (173 cases, 36%) followed by Mucosa Associated Lymphoid Tissue (MALT) lymphoma (77cases, 16%). Most common site of presentation were Gastrointestinal Tract (GIT) (117 cases, 24%) and Head and Neck region (HN) (117 cases, 24%). Conclusion: DLBCL, NOS was the most common subtype. GIT and HN region was the most common site of pENLs in present study. The frequency of pENLs in present study was comparable to few other Indian studies but was lower than Far Eastern studies. The frequency of Adult T-cell leukaemia/ Lymphoma (ATLL) was high which was not mentioned in similar studies on pENLs from India.

Microbiome composition of Anna's hummingbirds differs among regions of the gastrointestinal tract

The gastrointestinal (GI) microbiome is an important mediator and indicator of host physiology, health and fitness in many vertebrate systems, but sources of variation in microbiome composition within species are poorly understood, particularly in free‐ranging birds. Hummingbirds have GI anatomy and physiology similar to other avian species, but they have a relatively rapid gastrointestinal transit rate, which could affect microbiome structure. To date, it has not been elucidated if microbiomes isolated from feces and samples from sections of the GI tract differ in an avian organism that has a rapid gastrointestinal time. Here, we test the hypothesis that the microbiome in free‐ranging and wildlife rehabilitation‐sourced Anna's hummingbirds Calypte anna differ between fecal and samples from three sections of the GI tract and between birds that differ in sex, age and poxvirus infection status. We characterized bacterial composition in fecal and GI tract samples from Anna's hummingbirds by amplicon sequencing of the 16S rRNA gene. We found strong evidence of differentiation in bacterial composition among GI tract regions and compared it to fecal samples. Actinobacteria, primarily genus Corynebacterium, Firmicutes and Fusobacteria were abundant in bird samples from regions of the GI tract. In contrast, fecal bacterial communities were more diverse and variable compared to GI tract samples. Bacterial community composition differed between male and female hummingbirds and with bird age (hatch year vs after‐hatch year). Finally, birds with symptoms of avian poxvirus infection had a higher relative abundance of Staphylococcus spp. than birds with no symptoms of pox. Our results suggest that Anna's hummingbirds host differentiated microbiome among GI tract regions that is consistent among individual birds. The GI bacterial community also contained taxa not represented in fecal samples. This provides evidence for the possibility of a residential gut microbiome in Anna's hummingbirds, although functional significance of the bacterial microbiome remains unknown.

Type of Dietary Fiber Is Associated with Changes in Ileal and Hindgut Microbial Communities in Growing Pigs and Influences In Vitro Ileal and Hindgut Fermentation

BackgroundThe degree of ileal organic matter (OM) fermentation appears to be comparable to hindgut fermentation in growing pigs. ObjectivesThis study aimed to determine if dietary fiber sources with known different total gastrointestinal tract (GIT) fermentability in humans affect ileal and hindgut microbial communities and ileal fermentation in growing pigs used as an animal model for human adults. MethodsMale pigs (21 kg bodyweight; 9 wk old; PIC Camborough 46 × PIC boar 356L; n = 8/diet) were fed for 42 d a diet containing cellulose (CEL, low fermentability) as the sole fiber source (4.5%) or diets in which half of the CEL was replaced by moderately fermentable fiber, psyllium (PSY), or kiwifruit (KF) fiber. For each diet, terminal jejunal (substrate) and ileal (inoculum) digesta were collected from euthanized animals for in vitro ileal fermentation (2 h). Terminal ileal (substrate) and cecal (inoculum) digesta were used for in vitro hindgut fermentation (24 h). After in vitro fermentations, OM fermentation and short-chain fatty acid (SCFA) production were determined. Ileal digesta and feces were collected for microbial analysis. Data were analyzed by 2-factor ANOVA (diet × GIT region). ResultsIn vitro ileal OM fermentation was on average 22% and comparable to hindgut OM fermentation. Ileal and hindgut OM fermentation, SCFA production, and microbial community composition changed (P < 0.05) when CEL was partially replaced by KF or PSY. For instance, pigs fed the PSY diet had 3-fold higher (P ≤ 0.05) number of ileal and fecal bacteria than pigs fed the CEL and KF diets. Pigs fed the CEL diet had 4-fold higher (P ≤ 0.05) hindgut valeric acid production than pigs fed the other diets. ConclusionsIleal fermentation is quantitatively significant. Partial substitution of CEL with more fermentable fibers influences both ileal and hindgut microbial communities and the fermentation in growing pigs.

Recent Advances in Colon Drug Delivery Technology

Colon-targeted drug delivery technology; an approach of immense potential, has acquired tremendous significance for managing a number of ailments, particularly of the colon and for delivering therapeutic proteins and peptides systemically. The major hurdles for delivering drugs in the colonic region include absorption and degradation pathways in the upper gastrointestinal tract (GIT). To achieve a triumphant colonic delivery, the therapeutic agent must be protected from getting absorbed in the preliminary region of GIT to ensure its release in the proximal colon in a controlled way. The principle approaches, for instance, prodrug approach, pH sensitivity, timedependency (lag time), degradation by microbes, etc. have been effectively applied for obtaining colon targeted drug delivery. These approaches have accomplished immense relevance. Therefore, incessant attempts have been mainly focused on the design of colon targeted drug delivery systems having enhanced site-specificity along with the study of its versatile drug release kinetics to achieve diverse therapeutic requirements. The current manuscript illustrates the significance of different colon drug delivery systems and general considerations for designing colon targeting systems, including primary as well as novel approaches. Recent investigational studies carried out by scientific communities worldwide for the designing and preparation of various colon-targeted formulations along with their significant insights have been described. Recent patents, structure-property relationship and dissolution aspects pertaining to the colon-specific drug delivery have also been depicted.

Comparative study of the bacterial communities throughout the gastrointestinal tract in two beef cattle breeds.

Investigation of the compositional and functional characteristics of the gastrointestinal bacterial community in beef cattle breeds can improve our understanding of the influence of gastrointestinal tract (GIT) regions and host breeds on the bacterial community. In this study, 16S ribosomal RNA (16S rRNA) gene amplicon sequencing was used to characterize the bacterial communities in the rumen, duodenum, jejunum, ileum, caecum, and colon of Xuanhan yellow cattle (XHC) and Simmental crossbred cattle (SXC). The results showed that the diversity of the bacterial population was different in GIT regions of XHC and SXC (P < 0.05). In total, ten bacterial phyla, sixteen bacterial genera, and nine metabolic pathways were identified in the core bacteria. The phyla Firmicutes, Bacteroidetes, and Proteobacteria were predominant, but their proportions were different in GIT regions (P < 0.05). The diversity, structure, and composition of the bacteria in the rumen were similar between the breeds (P > 0.05), and the indices in the intestine showed significant differences (P < 0.05). Moreover, the composition and structure of the bacterial communities in the rumen, small intestine, and large intestine were different regardless of the breed. Thus, the bacterial communities were different among the gastrointestinal regions in each breed, and the bacterial community in the rumen had more stable characteristics than that in the intestine between two breeds. Further studies may focus on the minor microbial communities and the functions of GIT bacteria to better understand gut-microbe interactions. KEY POINTS: • Differences in bacteria among gastrointestinal regions differ in cattle breeds. • Differences between the breeds in the ruminal bacteria are less pronounced than differences in the intestinal bacteria.

Characterizing the bacterial community across the gastrointestinal tract of goats: Composition and potential function

The composition and function of the microbial community in the gastrointestinal tract (GIT) have increasingly captured the attention of nutritionists because these traits affect the nutrient utilization efficiency and health of host animals. Little information has been reported on these aspects of the goat GIT. This study used 12 female goats (weighing 20.70 ± 1.60 kg and 10 months of age) to examine the composition and function of the microbiota in the rumen, abomasum, jejunum, cecum, and colon. Total genomic DNA was extracted from chyme samples from different sections of the GIT, and the hypervariable region of the 16S rRNA gene was amplified by PCR using bacterial universal primers. The amplicons were sequenced on an Illumina MiSeq platform, and the biological information was analyzed using QIIME software. A total of 857 genera that belonged to 39 phyla were observed across the goat GIT, with Bacteroidetes and Firmicutes dominating. Our results revealed significant differences in the composition, diversity, and species abundance of the bacterial communities in the different sections of the GIT. However, the compositions of the bacterial communities in adjacent GIT segments showed similarities in addition to differences. The study indicated that there were significant differences in microbial function among the GIT regions. In particular, the relative abundances of genes involved in energy metabolism, amino acid metabolism, nucleotide metabolism, and glycan metabolism were overrepresented in samples from the forestomach, and genes related to energy metabolism, amino acid metabolism, and glycan metabolism were mainly enriched in samples from the small intestine. Additionally, the relative abundances of bacteria at the phylum and genus levels were significantly correlated with these metabolic functions. In general, there were significant differences in composition and potential function among the bacterial communities in the goat GIT.

Morphometric analysis of the gastrointestinal tract of four African muroid rodent species (Rhabdomys dilectus, Rhabdomys pumilio, Aethomys chrysophilus, and Lemniscomys rosalia).

Several muroid rodent species are distributed throughout southern Africa. Some species are reportedly classified as opportunistic omnivorous rodents consuming plant, seed, and insect material. This study aims to provide a detailed morphometric analysis of the gastrointestinal tract (GIT) of four such omnivorous species, including stomach content analysis. Fixed GIT specimens (n = 5 of each) of Rhabdomys dilectus (Mesic four-striped grass mouse), Rhabdomys pumilio (Xeric four-striped grass mouse), Aethomys chrysophilus (Red rock rat), and Lemniscomys rosalia (Single-striped grass mouse) were weighed. Length and circumference measurements of each anatomically distinct GIT region were determined to calculate the basal surface area (BSA). Histological sections from each GIT region were used to calculate a surface enlargement factor (SEF). The BSA and SEF were multiplied to calculate the luminal surface area (LSA) of each GIT region. Stomach content was analyzed both macroscopically and histologically. All species had a similar GIT morphology, namely a unilocular, hemiglandular stomach with a clear limiting ridge, which indicated the transition from stratified squamous epithelium to glandular epithelium. A large loosely spiralled cecum was present in all species. A narrowing of the cecal apex accompanied by lymph aggregates, confirmed histologically in both Rhabdomys species, indicated a cecal appendix. A single short colonic loop with a unique folding pattern for each species was present in the proximal colon. The colonic mucosal surface presented with proximal V-shaped, and distal longitudinal folds. Intermediate transitional S-shaped folds were present in three species (R. dilectus, R. pumilio, and L. rosalia). Colonic mucosal folds indicated hindgut specialization similar to other muroid rodents. The hindgut specialization was further supported by morphometric analysis, which indicated large BSA and LSA measurements in the cecum and colon. These adaptations are consistent with herbivory, despite stomach content analysis revealing omnivorous tendencies.

Characterisation of the bacterial community in the gastrointestinal tracts of elk (Cervus canadensis)

The resident bacteria of the gastrointestinal tract (GIT) and the behaviour of these microbes have been poorly characterised in elk as compared to other ruminant animal species such as sheep and cattle. In addition, most microbial community studies of deer gut have focused on rumen or faeces, while other parts of the GIT such as the small and large intestine have received little attention. To address this issue, the present study investigated the diversity of the GIT bacterial community in elk (Cervus canadensis) by 16S rRNA pyrosequencing analysis. Eight distinct GIT segments including the stomach (rumen, omasum, and abomasum), small intestine (duodenum and jejunum), and large intestine (cecum, colon, and rectum) obtained from four elks were examined. We found that bacterial richness and diversity were higher in the stomach and large intestine than in the small intestine (P < 0.05). A total of 733 genera belonging to 26 phyla were distributed throughout elk GITs, with Firmicutes, Bacteroidetes, and Proteobacteria identified as the predominant phyla. In addition, there was spatial heterogeneity in the composition, diversity, and species abundance of microbiota in the GIT (P < 0.0001). To the best of our knowledge, this is the first study to characterise bacterial communities from eight GIT regions of elk by 16S rRNA pyrosequencing.

Potential impact of inorganic nanoparticles on macronutrient digestion: titanium dioxide nanoparticles slightly reduce lipid digestion under simulated gastrointestinal conditions

Titanium dioxide (TiO2) particles are used in some food products to alter their optical properties, such as whiteness or brightness. These additives typically contain a population of TiO2 nanoparticles (d < 100 nm), which has led to concern about their potential toxicity. The objective of this study was to examine the impact of TiO2 particles on the gastrointestinal fate of oil-in-water emulsions using a simulated gastrointestinal tract (GIT) that includes mouth, stomach, and small intestine phases. Theoretical predictions suggested that TiO2 nanoparticles might inhibit lipid digestion through two physicochemical mechanisms: (i) a fraction of the lipase adsorbs to TiO2 particle surfaces, thereby reducing the amount available to hydrolyze lipid droplets; (ii) some TiO2 particles adsorb to the surfaces of lipid droplets, thereby reducing the lipid surface area exposed to lipase. The importance of these mechanisms was tested by passing protein-coated lipid droplets (2%, w/w) through the simulated GIT in the absence and presence of TiO2 (0.5%, w/w) nanoparticles (18 nm) and fine particles (167 nm). Changes in particle characteristics (size, organization, and charge) and lipid digestion were then measured. Both TiO2 nanoparticles and fine particles had little impact on the aggregation state and charge of the lipid droplets in the different GIT regions, as well as on the rate and extent of lipid digestion. This suggests that the theoretically predicted impact of particle size on lipid digestion was not seen in practice.

Control of protein digestion under simulated gastrointestinal conditions using biopolymer microgels

Controlling the rate and extent of protein digestion within different regions of the human gastrointestinal tract (GIT) is important for regulating hormonal responses (such as hunger, satiety, and satiation) and immune responses (such as allergenicity). In this study, hydrogel beads (biopolymer microgels) were fabricated by injecting a solution of anionic alginate molecules into a solution of cationic calcium ions using a vibrating extrusion device. A model food protein (whey protein isolate, WPI) was mixed with the alginate solution prior to bead formation. The impact of thermal processing (80°C, 15min) of the WPI before or after microgel formation was examined to determine the impact of protein denaturation and aggregation on encapsulation efficiency and retention. Heat-denaturation of the protein prior to microgel formation led to the highest encapsulation efficiency and retention, which was attributed to the formation of a cold-set protein gel inside the beads. Simulated GIT studies indicated that protein encapsulation in the microgels retarded its digestion in the stomach (around 3.7% digested), but not in the small intestine (around 19.6% digested). The denatured and native proteins were digested differently in different GIT regions: denatured protein digested faster in the stomach (around 11% digested), whereas native protein digested faster in the small intestine (around 41% digested). These results could provide valuable information for the design of microgel-based delivery systems to regulate protein digestion and peptide release in the GIT.

Breast cancer metastases to the stomach and colon mimicking primary gastrointestinal cancer: Four cases and literature review

Intraluminal gastric and colonic metastases of the breast cancer are very rare and may sometimes prove a diagnostic dilemma to distinguish from primary gastric and colonic cancers. It is important to make the distinction in order to navigate the proper treatment approach, which is a systemic treatment rather than surgery if the disease is me- tastatic. The spread to the gastrointestinal (GI) tract is more frequent in lobular histology and according to a number of investigators, it is related to a particular tropism of lobular cells toward gastrointestinal mucosa. Any region of GI tract may be involved, from the tongue to the anus. Over the last decade, among the 1,100 breast cancer cases registered at our institutions, we diagnosed four patients with breast cancer who had metastases to the stomach and/or colon and presented symptoms that simulated primary gastrointestinal cancer. A total of 84 out of the 1,100 patients experienced invasive lobular histology. Among the four patients with GI tract metastases, three were diagnosed with lobular hist- ology – two of whom had the signet ring cell subtype. The remaining patient was diagnosed with triple negative invasive ductal carcinoma; however, it clinically resembled invasive lobular carcinoma. Clinical and pathological features of these cases, as well as the review of related literature are discussed in this report.

Characterization of melatonin synthesis in the gastrointestinal tract of rainbow trout (Oncorhynchus mykiss): distribution, relation with serotonin, daily rhythms and photoperiod regulation.

Melatonin is synthesized in peripheral locations of vertebrates, including the gastrointestinal tract (GIT). In teleost, information regarding this topic is scarce. Here we studied the presence and synthesis of melatonin at the rainbow trout GIT. Different sections of trout GIT (from esophagus to hindgut) were dissected out and assayed for contents of melatonin, serotonin (5-HT) and its metabolite, 5-hydroxyindole acetic acid, as well as for aanat1, aanat2 and hiomt mRNA abundance. A trout group was pinealectomized to evaluate changes in plasma and gut melatonin content. Finally, the daily profile of melatonin and 5-HT content, and aanat1, aanat2 and hiomt mRNA abundance were analyzed in gut of trout kept under normal lighting, and then under constant darkness. Melatonin was detected in all GIT regions with higher concentrations in the muscular wall than in the mucosa, a similar trend to that of 5-HT. In contrast, transcripts of melatonin synthesis enzymes were more abundant in the mucosa. Pinealectomy did not affect melatonin levels in midgut and hindgut either at day or at night. Additionally, no daily rhythms could be defined for melatonin content in gut tissues but increases during late light phase and at midnight occurred. However, aanat1, aanat2 and hiomt mRNA abundance showed clear daily rhythms with peaks at night. These rhythms remained with a 3-h phase advanced peak in fish exposed to constant darkness. Our results provide clear evidence for a local synthesis of melatonin in trout GIT that might be influenced by the content of 5-HT in the tissue. The process is affected by environmental light cycle and is likely to be under circadian regulation.

Phylogenetic Analysis of Bacterial Communities in Different Regions of the Gastrointestinal Tract of Agkistrodon piscivorus, the Cottonmouth Snake.

Vertebrates are metagenomic organisms in that they are composed not only of their own genes but also those of their associated microbial cells. The majority of these associated microorganisms are found in the gastrointestinal tract (GIT) and presumably assist in processes such as energy and nutrient acquisition. Few studies have investigated the associated gut bacterial communities of non-mammalian vertebrates, and most rely on captive animals and/or fecal samples only. Here we investigate the gut bacterial community composition of a squamate reptile, the cottonmouth snake, Agkistrodon piscivorus through pyrosequencing of the bacterial 16S rRNA gene. We characterize the bacterial communities present in the small intestine, large intestine and cloaca. Many bacterial lineages present have been reported by other vertebrate gut community studies, but we also recovered unexpected bacteria that may be unique to squamate gut communities. Bacterial communities were not phylogenetically clustered according to GIT region, but there were statistically significant differences in community composition between regions. Additionally we demonstrate the utility of using cloacal swabs as a method for sampling snake gut bacterial communities.