scholarly journals Electrochemical activation of diamond microelectrodes: implications for the in vitro measurement of serotonin in the bowel

The Analyst ◽  
2014 ◽  
Vol 139 (12) ◽  
pp. 3160-3166 ◽  
Author(s):  
Boris Duran ◽  
Ricardo F. Brocenschi ◽  
Marion France ◽  
James J. Galligan ◽  
Greg M. Swain
Keyword(s):  
Electrochemical Activation ◽  
Gi Tract ◽  
Cathodic Pretreatment

Diamond microelectrodes can be reproducibly activated during the in vitro detection of serotonin in the GI tract by cathodic pretreatment.

scholarly journals A possible role for hypoxia-induced apelin expression in enteric cell proliferation

2008 ◽  
Vol 294 (6) ◽  
pp. R1832-R1839 ◽  
Author(s):  
Song Han ◽  
Guiyun Wang ◽  
Xiang Qi ◽  
Heung M. Lee ◽  
Ella W. Englander ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Epithelial Cell ◽  
Intestinal Inflammation ◽  
Acute Hypoxia ◽  
Hypoxia Inducible Factor ◽  
Mrna Levels ◽  
Epithelial Cell Proliferation ◽  
Gi Tract ◽  
Rat Pups

Apelin is the endogenous ligand for the APJ receptor, and apelin and APJ are expressed in the gastrointestinal (GI) tract. Intestinal inflammation increases intestinal hypoxia-inducible factor (HIF) and apelin expression. Hypoxia and inflammation are closely linked cellular insults. The purpose of these studies was to investigate the influence of hypoxia on enteric apelin expression. Exposure of rat pups to acute hypoxia increased hepatic, stomach-duodenal, and colonic apelin mRNA levels 10-, 2-, and 2-fold, respectively ( P < 0.05 vs. controls). Hypoxia also increased colonic APJ mRNA levels, and apelin treatment during hypoxia exposure enhanced colonic APJ mRNA levels further. In vitro hypoxia also increased apelin and APJ mRNA levels. The hypoxia-induced elevation in apelin expression is most likely mediated by HIF, since HIF-activated apelin transcriptional activity is dependent on an intact, putative HIF binding site in the rat apelin promoter. Acute exposure of rat pups to hypoxia lowered gastric and colonic epithelial cell proliferation; hypoxia in combination with apelin treatment increased epithelial proliferation by 50%. In vitro apelin treatment of enteric cells exposed to hypoxia increased cell proliferation. Apelin treatment during normoxia was ineffective. Our studies imply that the elevation in apelin expression during hypoxia and inflammation in the GI tract functions in part to stimulate epithelial cell proliferation.

scholarly journals Germinant Synergy FacilitatesClostridium difficileSpore Germination under Physiological Conditions

mSphere ◽  
2018 ◽  
Vol 3 (5) ◽  
Author(s):  
Travis J. Kochan ◽  
Michelle S. Shoshiev ◽  
Jessica L. Hastie ◽  
Madeline J. Somers ◽  
Yael M. Plotnick ◽  
...  
Keyword(s):  
Amino Acids ◽  
Clostridium Difficile ◽  
Spore Germination ◽  
Bile Salts ◽  
Gi Tract ◽  
Infectious Diarrhea ◽  
Content Type ◽  
Increased Risk ◽  
Calcium Reabsorption

ABSTRACTClostridium difficileis a Gram-positive obligate anaerobe that forms spores in order to survive for long periods in the unfavorable environment outside a host.C. difficileis the leading cause of nosocomial infectious diarrhea worldwide.C. difficileinfection (CDI) arises after a patient treated with broad-spectrum antibiotics ingests infectious spores. The first step inC. difficilepathogenesis is the metabolic reactivation of dormant spores within the gastrointestinal (GI) tract through a process known as germination. In this work, we aim to elucidate the specific conditions and the location within the GI tract that facilitate this process. Our data suggest thatC. difficilegermination occurs through a two-step biochemical process that is regulated by pH and bile salts, amino acids, and calcium present within the GI tract. Maximal germination occurs at a pH ranging from 6.5 to 8.5 in the terminal small intestine prior to bile salt and calcium reabsorption by the host. Germination can be initiated by lower concentrations of germinants when spores are incubated with a combination of bile salts, calcium, and amino acids, and this synergy is dependent on the availability of calcium. The synergy described here allows germination to proceed in the presence of inhibitory bile salts and at physiological concentrations of germinants, effectively decreasing the concentrations of nutrients required to initiate an essential step of pathogenesis.IMPORTANCEClostridium difficileis an anaerobic spore-forming human pathogen that is the leading cause of nosocomial infectious diarrhea worldwide. Germination of infectious spores is the first step in the development of aC. difficileinfection (CDI) after ingestion and passage through the stomach. This study investigates the specific conditions that facilitateC. difficilespore germination, including the following: location within the gastrointestinal (GI) tract, pH, temperature, and germinant concentration. The germinants that have been identified in culture include combinations of bile salts and amino acids or bile salts and calcium, butin vitro, these function at concentrations that far exceed normal physiological ranges normally found in the mammalian GI tract. In this work, we describe and quantify a previously unreported synergy observed when bile salts, calcium, and amino acids are added together. These germinant cocktails improve germination efficiency by decreasing the required concentrations of germinants to physiologically relevant levels. Combinations of multiple germinant types are also able to overcome the effects of inhibitory bile salts. In addition, we propose that the acidic conditions within the GI tract regulateC. difficilespore germination and could provide a biological explanation for why patients taking proton pump inhibitors are associated with increased risk of developing a CDI.

N tau-methylhistidine release: contributions of rat skeletal muscle, GI tract, and skin

1982 ◽  
Vol 243 (4) ◽  
pp. E293-E297 ◽  
Author(s):  
S. J. Wassner ◽  
J. B. Li
Keyword(s):  
Skeletal Muscle ◽  
Gastrointestinal Tract ◽  
Soft Tissue ◽  
Fractional Catabolic Rate ◽  
Gi Tract ◽  
Rat Skeletal Muscle ◽  
Catabolic Rate ◽  
Total Body

The relative contributions of skeletal muscle, gastrointestinal tract, and skin to urinary N tau-methylhistidine (MH) excretion were estimated during in vitro studies using the rat hemicorpus preparation. After 0.5 h of perfusion, MH release into the perfusate was linear for 3 h and averaged 29.8 nmol . h-1 . 100 g hemicorpus-1. In vivo, 24-h urinary MH excretion averaged 37.3 nmol . h-1 . 100 g body wt-1. The ratio of soft tissue to skin weight is equal (3.2:1) in the whole rat and in the hemicorpus. The gastrointestinal tract released 16.0 nmol . h-1 . 100 g body wt-1 or approximately 41% of the total urinary MH excretion. Preparations perfused with or without skin showed modest differences in the rate of MH release that were not statistically significant. Skeletal muscle contains 89.8% of total body MH content, whereas gastrointestinal tract and skin contain 3.8 and 6.4%, respectively. Gastrointestinal tract actomyosin turns over rapidly with a fractional catabolic rate of 24%/day versus 1.4%/day for skeletal muscle actomyosin.

scholarly journals Light-degradable hydrogels as dynamic triggers for gastrointestinal applications

2020 ◽  
Vol 6 (3) ◽  
pp. eaay0065 ◽  
Author(s):  
Ritu Raman ◽  
Tiffany Hua ◽  
Declan Gwynne ◽  
Joy Collins ◽  
Siddartha Tamang ◽  
...  
Keyword(s):  
Ex Vivo ◽  
Implantable Devices ◽  
Large Animal Model ◽  
Large Animal ◽  
Gi Tract ◽  
Biomedical Device ◽  
Precise Tool ◽  
And Performance

Triggerable materials capable of being degraded by selective stimuli stand to transform our capacity to precisely control biomedical device activity and performance while reducing the need for invasive interventions. Here, we describe the development of a modular and tunable light-triggerable hydrogel system capable of interfacing with implantable devices. We apply these materials to two applications in the gastrointestinal (GI) tract: a bariatric balloon and an esophageal stent. We demonstrate biocompatibility and on-demand triggering of the material in vitro, ex vivo, and in vivo. Moreover, we characterize performance of the system in a porcine large animal model with an accompanying ingestible LED. Light-triggerable hydrogels have the potential to be applied broadly throughout the GI tract and other anatomic areas. By demonstrating the first use of light-degradable hydrogels in vivo, we provide biomedical engineers and clinicians with a previously unavailable, safe, dynamically deliverable, and precise tool to design dynamically actuated implantable devices.

scholarly journals Mechanistic Features of the Enterococcal pCF10 Sex Pheromone Response and the Biology ofEnterococcus faecalisin Its Natural Habitat

2018 ◽  
Vol 200 (14) ◽  
pp. e00733-17 ◽  
Author(s):  
Rebecca J. Breuer ◽  
Helmut Hirt ◽  
Gary M. Dunny
Keyword(s):  
Opportunistic Infections ◽  
Natural Habitat ◽  
Test Tube ◽  
Gi Tract ◽  
Pheromone Response ◽  
Content Type ◽  
Pheromone Signaling ◽  
Control Transfer

ABSTRACTConjugative transfer of plasmids in enterococci is promoted by intercellular communication using peptide pheromones. The regulatory mechanisms that control transfer have been extensively studiedin vitro. However, the complicated systems that regulate the spread of these plasmids did not evolve in the laboratory test tube, and remarkably little is known about this form of signaling in the intestinal tract, the primary niche of these organisms. Because the evolution ofEnterococcus faecalisstrains and their coresident pheromone-inducible plasmids, such as pCF10, have occurred in the gastrointestinal (GI) tract, it is important to consider the functions controlled by pheromones in light of this ecology. This review summarizes our current understanding of the pCF10-encoded pheromone response. We consider how selective pressures in the natural environment may have selected for the complex and very tightly regulated systems controlling conjugation, and we pay special attention to the ecology of enterococci and the pCF10 plasmid as a gut commensal. We summarize the results of recent studies of the pheromone response at the single-cell level, as well as those of the first experiments demonstrating a role for pheromone signaling in plasmid transfer and in GI tract competitive fitness. These results will serve as a foundation for furtherin vivostudies that could lead to novel interventions to reduce opportunistic infections and the spread of antibiotic resistance.

scholarly journals A Review of the Role of Neurotensin and Its Receptors in Colorectal Cancer

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Shengyang Qiu ◽  
Gianluca Pellino ◽  
Francesca Fiorentino ◽  
Shahnawaz Rasheed ◽  
Ara Darzi ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Animal Studies ◽  
In Vivo Studies ◽  
Signalling Pathways ◽  
Diagnostic Biomarker ◽  
Gi Tract ◽  
Cellular Receptors

Neurotensin (NTS) is a physiologically occurring hormone which affects the function of the gastrointestinal (GI) tract. In recent years, NTS, acting through its cellular receptors (NTSR), has been implicated in the carcinogenesis of several cancers. In colorectal cancer (CRC), a significant body of evidence, from in vitro and in vivo studies, is available which elucidates the molecular biology of NTS/NTSR signalling and the resultant growth of CRC cells. There is growing clinical data from human studies which corroborate the role NTS/NTSR plays in the development of human CRC. Furthermore, blockade and modulation of the NTS/NTSR signalling pathways appears to reduce CRC growth in cell cultures and animal studies. Lastly, NTS/NTSR also shows potential of being utilised as a diagnostic biomarker for cancers as well as targets for functional imaging. We summarise the existing evidence and understanding of the role of NTS and its receptors in CRC.

scholarly journals In SituPrebiotics for Weaning Piglets:In VitroProduction and Fermentation of Potato Galacto-Rhamnogalacturonan

2014 ◽  
Vol 81 (5) ◽  
pp. 1668-1678 ◽  
Author(s):  
Mikael Lenz Strube ◽  
Helle Christine Ravn ◽  
Hans-Christian Ingerslev ◽  
Anne Strunge Meyer ◽  
Mette Boye
Keyword(s):  
Terminal Ileum ◽  
Animal Studies ◽  
Waste Product ◽  
Economic Loss ◽  
Gut Contents ◽  
Soluble Fiber ◽  
Gi Tract ◽  
Ecological Disturbance ◽  
Content Type

ABSTRACTPostweaning diarrhea (PWD) in pigs is a leading cause of economic loss in pork production worldwide. The current practice of using antibiotics and zinc to treat PWD is unsustainable due to the potential of antibiotic resistance and ecological disturbance, and novel methods are required. In this study, anin vitromodel was used to test the possibility of producing prebiotic fiberin situin the gastrointestinal (GI) tract of the piglet and the prebiotic activity of the resulting fiber in the terminal ileum. Soluble fiber was successfully produced from potato pulp, an industrial waste product, with the minimal enzyme dose in a simulated upper GI tract model extracting 26.9% of the initial dry matter. The fiber was rich in galactose and galacturonic acid and was fermented at 2.5, 5, or 10 g/liter in a glucose-free medium inoculated with the gut contents of piglet terminal ileum. Fermentations of 5 g/liter inulin or 5 g/liter of a purified potato fiber were used as controls. The fibers showed high fermentability, evident by a dose-dependent drop in pH and an increase in the organic acid content, with lactate in particular being increased. Deep sequencing showed a significant increase in the numbers ofLactobacillusandVeillonellaorganisms and an insignificant increase in the numbers ofClostridiumorganisms as well as a decrease in the numbers ofStreptococcusorganisms. Multivariate analysis showed clustering of the treatment groups, with the group treated with purified potato fiber being clearly separated from the other groups, as the microbiota composition was 60%Lactobacillusand almost free ofClostridium. For animal studies, a dosage corresponding to the 5-g/liter treatment is suggested.

scholarly journals Survival of vaccine-induced human milk SARS-CoV-2 IgG and IgA immunoglobulins across simulated human infant gastrointestinal digestion

2021 ◽  
Author(s):  
Myrtani Pieri ◽  
Vicky Nicolaidou ◽  
Irene Paphiti ◽  
Spyros Pipis ◽  
Kyriacos Felekkis ◽  
...  
Keyword(s):  
Human Milk ◽  
Enzymatic Degradation ◽  
Natural Infection ◽  
In Vitro Digestion ◽  
Human Infant ◽  
European Medicines Agency ◽  
Igg Antibodies ◽  
Gi Tract ◽  
Lactating Mothers

Four vaccines have been approved to date by the European Medicines Agency for the management of the COVID-19 pandemic in Europe, with all four being targeted to adults over 18 years of age. One way to protect the younger population such as infants or younger children until pediatric vaccines are licensed is through passive immunity via breastfeeding. Recent evidence points to the fact that human milk contains immunoglobulins (Ig) against the SARS-CoV-2 virus, both after natural infection or vaccination, but it is not known whether these antibodies can resist enzymatic degradation during digestion in the infant gastrointestinal (GI) tract or indeed protect the consumers. Here, we describe our preliminary experiments where we validated commercially available ELISA kits to detect IgA and IgG antibodies in human milk from two lactating mothers vaccinated with either the Pfizer/BioNTech or the Astra Zeneca vaccine, and the effect of a static in vitro digestion protocol on the IgA and IgG concentrations. Our data, even preliminary, provide an indication that the IgA antibodies produced after vaccination with the Pfizer/BioNTech vaccine resist the gastric phase but are degraded during the intestinal phase of infant digestion, whereas the IgGs are more prone to degradation in both phases of digestion. We are in the process of recruiting more individuals to further evaluate the vaccine-induced immunoglobulin profile of breastmilk, and the extent to which these antibodies can resist digestion in the infant GI tract.

scholarly journals Masked trichothecene and zearalenone mycotoxins withstand digestion and absorption in the upper GI tract but are efficiently hydrolyzed by human gut microbiota in vitro

2017 ◽  
Vol 61 (4) ◽  
pp. 1600680 ◽  
Author(s):  
Silvia W. Gratz ◽  
Reshma Dinesh ◽  
Tomoya Yoshinari ◽  
Grietje Holtrop ◽  
Anthony J. Richardson ◽  
...  
Keyword(s):  
Gut Microbiota ◽  
Gi Tract ◽  
Human Gut ◽  
Upper Gi ◽  
Human Gut Microbiota ◽  
Upper Gi Tract

scholarly journals Gastrointestinal organoids: a next-generation tool for modeling human development

2020 ◽  
Vol 319 (3) ◽  
pp. G375-G381 ◽  
Author(s):  
Akaljot Singh ◽  
Holly M. Poling ◽  
Jason R. Spence ◽  
James M. Wells ◽  
Michael A. Helmrath
Keyword(s):  
Stem Cells ◽  
Human Development ◽  
Pluripotent Stem Cells ◽  
Three Dimensional ◽  
Immunocompromised Host ◽  
Dimensional Structure ◽  
Gi Tract ◽  
Microscopic Anatomy ◽  
Complex Signaling

Gastrointestinal organoids are an exciting new tool for modeling human development, physiology, and disease in human tissue. Derived from pluripotent stem cells, gastrointestinal organoids consist of epithelial and mesenchymal cells organized in an intricate, three-dimensional structure that recapitulates the physiology and microscopic anatomy of the human gastrointestinal (GI) tract. In vitro derivation of gastrointestinal organoids from definitive endoderm has permitted an exploration of the complex signaling pathways required for the initial maturation of each individual gastrointestinal organ. Further maturation beyond an early fetal state currently requires transplantation into an immunocompromised host. Transplantation-induced maturation provides an opportunity to functionally interrogate the key mechanisms underlying development of the human GI tract. Gastrointestinal organoids can also be used to model human diseases and ultimately may serve as the basis for developing novel, personalized therapies for human intestinal diseases.

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