Gastric organoids: Advancing the study of H. pylori pathogenesis and inflammation.

For decades, traditional in vitro and in vivo models used for the study of Helicobacter pylori infection have relied heavily on the use of gastric cancer cell lines and rodents. Major challenges faced by these methods have been the inability to study cancer initiation in already cancerous cell lines, and the difficulty in translating results obtained in animal models due to genetic differences. These challenges have prevented a thorough understanding of the pathogenesis of disease and slowed the development of cancer therapies and a suitable vaccine against the pathogen. In recent years, the development of gastric organoids has provided great advantages over the traditional in vivo and in vitro models due to their similarities to the human stomach in vivo, their ease of use, and the capacity for long-term culture. This review discusses the advantages and limitations of existing in vivo and in vitro models of H. pylori infection, and how gastric organoids have been applied to study H. pylori pathogenesis, with a focus on how the pathogen interacts with the gastric epithelium, inflammatory processes, epithelial repair, and cancer initiation. The potential applications of organoids to address more complex questions on the role of hormones, vaccine-induced immunity are also discussed.

Homeostasis and Cancer Initiation: Organoids as Models to Study the Initiation of Gastric Cancer.

Gastric cancer represents a significant disease burden worldwide. The factors that initiate cancer are not well understood. Chronic inflammation such as that triggered by H. pylori infection is the most significant cause of gastric cancer. In recent years, organoid cultures developed from human and animal adult stem cells have facilitated great advances in our understanding of gastric homeostasis. Organoid models are now being exploited to investigate the role of host genetics and bacterial factors on proliferation and DNA damage in gastric stem cells. The impact of a chronic inflammatory state on gastric stem cells and the stroma has been less well addressed. This review discusses what we have learned from the use of organoid models to investigate cancer initiation, and highlights questions on the contribution of the microbiota, chronic inflammatory milieu, and stromal cells that can now be addressed by more complex coculture models.

A two-step dilution tris-egg yolk extender containing Equex STM significantly improves sperm cryopreservation in the African wild dog (Lycaon pictus).

Conservation management of endangered African wild dogs (AWD; Lycaon pictus) can benefit greatly from development of sperm freezing and artificial insemination. Previous freezing attempts yielded nearly 0% motile sperm within 2 h of thawing. In this study, two canine freezing protocols were tested: Protocol 1: a one-step dilution in TRIS-20% egg yolk containing 8% glycerol; and Protocol 2: a two-step dilution in TRIS-20% egg yolk containing a final extender concentration of 5% glycerol and 0.5% Equex STM, coupled with a TRIS-citrate-fructose thawing solution. Semen was collected by electroejaculation from n = 24 AWDs, of which eight ejaculates of sufficient quality (four good quality with initial sperm motility of 75.0 ±â€¯4.4% and four poor quality; showing rapid decrease in sperm motility to 3.3 ±â€¯3.3% prior to freezing) were frozen. For good quality samples, motility and sperm motility index persisted for up to 8 h for Protocol 2, and was higher between 2 and 6 h after thawing with a decrease from 4 h of incubation. Motility dropped to nearly 0% after 2 h incubation for Protocol 1. Viability was higher for Protocol 2 throughout the 8 h of incubation, with a decrease after 6 h, compared to 4 h for Protocol 1. Acrosome integrity was higher for Protocol 2 throughout post-thaw incubation, with a decrease after 2 h for both protocols. Protocols did not differ in normal sperm morphology or DNA integrity. Poor quality samples yielded similar results, except for acrosome integrity, which declined for Protocol 2. In conclusion, a two-step dilution in TRIS-egg yolk-glycerol extender containing Equex STM yields significantly improved post-thaw quality and longevity of AWD spermatozoa, making it suitable for sperm banking and artificial insemination initiatives.

Plasticity of neuroeffector transmission during bowel inflammation1.

Altered gastrointestinal (GI) function contributes to the debilitating symptoms of inflammatory bowel diseases (IBD). Nerve circuits contained within the gut wall and outside of the gut play important roles in modulating motility, mucosal fluid transport, and blood flow. The structure and function of these neuronal populations change during IBD. Superimposed on this plasticity is a diminished responsiveness of effector cells - smooth muscle cells, enterocytes, and vascular endothelial cells - to neurotransmitters. The net result is a breakdown in the precisely orchestrated coordination of motility, fluid secretion, and GI blood flow required for health. In this review, we consider how inflammation-induced changes to the effector innervation of these tissues, and changes to the tissues themselves, contribute to defective GI function in models of IBD. We also explore the evidence that reversing neuronal plasticity is sufficient to normalize function during IBD.

Excitability and Synaptic Transmission in the Enteric Nervous System: Does Diet Play a Role?

Changes in diet are a challenge to the gastrointestinal tract which needs to alter its processing mechanisms to continue to process nutrients and maintain health. In particular, the enteric nervous system (ENS) needs to adapt its motor and secretory programs to deal with changes in nutrient type and load in order to optimise nutrient absorption.The nerve circuits in the gut are complex, and the numbers and types of neurons make recordings of specific cell types difficult, time-consuming, and prone to sampling errors. Nonetheless, traditional research methods like intracellular electrophysiological approaches have provided the basis for our understanding of the ENS circuitry. In particular, animal models of intestinal inflammation have shown us that we can document changes to neuronal excitability and synaptic transmission.Recent studies examining diet-induced changes to ENS programming have opted to use fast imaging techniques to reveal changes in neuron function. Advances in imaging techniques using voltage- or calcium-sensitive dyes to record neuronal activity promise to overcome many limitations inherent to electrophysiological approaches. Imaging techniques allow access to a wide range of ENS phenotypes and to the changes they undergo during dietary challenges. These sorts of studies have shown that dietary variation or obesity can change how the ENS processes information-in effect reprogramming the ENS. In this review, the data gathered from intracellular recordings will be compared with measurements made using imaging techniques in an effort to determine if the lessons learnt from inflammatory changes are relevant to the understanding of diet-induced reprogramming.

Alternative splicing of the TRPC3 ion channel calmodulin/IP3 receptor-binding domain in the hindbrain enhances cation flux.

Canonical transient receptor potential (TRPC3) nonselective cation channels are effectors of G-protein-coupled receptors (GPCRs), activated via phospholipase C-diacylglycerol signaling. In cerebellar Purkinje cells, TRPC3 channels cause the metabotropic glutamate receptor (mGluR)-mediated slow EPSC (sEPSC). TRPC3 channels also provide negative feedback regulation of cytosolic Ca(2+), mediated by a C terminus "calmodulin and inositol trisphosphate receptor binding" (CIRB) domain. Here we report the alternative splicing of the TRPC3 mRNA transcript (designated TRPC3c), resulting in omission of exon 9 (approximately half of the CIRB domain) in mice, rats, and guinea pigs. TRPC3c expression is brain region specific, with prevalence in the cerebellum and brainstem. The TRPC3c channels expressed in HEK293 cells exhibit increased basal and GPCR-activated channel currents, and increased Ca(2+) fluorescence responses, compared with the previously characterized (TRPC3b) isoform when activated via either the endogenous M3 muscarinic acetylcholine receptor, or via coexpressed mGluR1. GPCR-induced TRPC3c channel opening rate (cell-attached patch) matched the maximum activation achieved with inside-out patches with zero cytosolic Ca(2+), whereas the GPCR-induced TRPC3b activation frequency was significantly less. Both TRPC3 channel isoforms were blocked with 2 mm Ca(2+), attributable to CIRB domain regulation. In addition, genistein blocked Purkinje cell (S)-2-amino-2-(3,5-dihydroxyphenyl) acetic acid (mGluR1)-activated TPRC3 current as for recombinant TRPC3c current. This novel TRPC3c ion channel therefore has enhanced efficacy as a neuronal GPCR-Ca(2+) signaling effector, and is associated with sensorimotor coordination, neuronal development, and brain injury.

Increased caveolae density and caveolin-1 expression accompany impaired NO-mediated vasorelaxation in diet-induced obesity.

Diet-induced obesity induces changes in mechanisms that are essential for the regulation of normal artery function, and in particular the function of the vascular endothelium. Using a rodent model that reflects the characteristics of human dietary obesity, in the rat saphenous artery we have previously demonstrated that endothelium-dependent vasodilation shifts from an entirely nitric oxide (NO)-mediated mechanism to one involving upregulation of myoendothelial gap junctions and intermediate conductance calcium-activated potassium channel activity and expression. This study investigates the changes in NO-mediated mechanisms that accompany this shift. In saphenous arteries from controls fed a normal chow diet, acetylcholine-mediated endothelium-dependent vasodilation was blocked by NO synthase and soluble guanylyl cyclase inhibitors, but in equivalent arteries from obese animals sensitivity to these agents was reduced. The expression of endothelial NO synthase (eNOS) and caveolin-3 in rat saphenous arteries was unaffected by obesity, whilst that of caveolin-1 monomer and large oligomeric complexes of caveolins-1 and -2 were increased in membrane-enriched samples. The density of caveolae was increased at the membrane and cytoplasm of endothelial and smooth muscle cells of saphenous arteries from obese rats. Dissociation of eNOS from caveolin-1, as a prerequisite for activation of the enzyme, may be compromised and thereby impair NO-mediated vasodilation in the saphenous artery from diet-induced obese rats. Such altered signaling mechanisms in obesity-related vascular disease represent significant potential targets for therapeutic intervention.

Enhanced contractility in pregnancy is associated with augmented TRPC3, L-type, and T-type voltage-dependent calcium channel function in rat uterine radial artery.

In pregnancy, α-adrenoceptor-mediated vasoconstriction is augmented in uterine radial arteries and is accompanied by underlying changes in smooth muscle (SM) Ca(2+) activity. This study aims to determine the Ca(2+) entry channels associated with altered vasoconstriction in pregnancy, with the hypothesis that augmented vasoconstriction involves transient receptor potential canonical type-3 (TRPC3) and L- and T-type voltage-dependent Ca(2+) channels. Immunohistochemistry showed TRPC3, L-type Cav1.2 (as the α1C subunit), T-type Cav3.1 (α1G), and Cav3.2 (α1H) localization to the uterine radial artery SM. Fluorescence intensity of TRPC3, Cav1.2, and Cav3.2 was increased, and Cav3.1 decreased in radial artery SM from pregnant rats. Western blot analysis confirmed increased TRPC3 protein expression in the radial artery from pregnant rats. Pressure myography incorporating pharmacological intervention to examine the role of these channels in uterine radial arteries showed an attenuation of phenylephrine (PE)-induced constriction with Pyr3 {1-[4-[(2,3,3-trichloro-1-oxo-2-propen-1-yl)amino]phenyl]-5-(trifluoromethyl)-1H-pyrazole-4-carboxylic acid}-mediated TRPC3 inhibition or with nifedipine-mediated L-type channel block alone in vessels from pregnant rats; both effects of which were diminished in radial arteries from nonpregnant rats. Combined TRPC3 and L-type inhibition attenuated PE-induced constriction in radial arteries, and the residual vasoconstriction was reduced and abolished with T-type channel block with NNC 55-0396 in arteries from nonpregnant and pregnant rats, respectively. With SM Ca(2+) stores depleted and in the presence of PE, nifedipine, and NNC 55-0396, blockade of TRPC3 reversed PE-induced constriction. These data suggest that TRPC3 channels act synergistically with L- and T-type channels to modulate radial artery vasoconstriction, with the mechanism being augmented in pregnancy.

Pregnancy-induced remodelling and enhanced endothelium-derived hyperpolarization-type vasodilator activity in rat uterine radial artery: transient receptor potential vanilloid type 4 channels, caveolae and myoendothelial gap junctions.

In pregnancy, the vasculature of the uterus undergoes rapid remodelling to increase blood flow and maintain perfusion to the fetus. The present study determines the distribution and density of caveolae, transient receptor potential vanilloid type 4 channels (TRPV4) and myoendothelial gap junctions, and the relative contribution of related endothelium-dependent vasodilator components in uterine radial arteries of control virgin non-pregnant and 20-day late-pregnant rats. The hypothesis examined is that specific components of endothelium-dependent vasodilator mechanisms are altered in pregnancy-related uterine radial artery remodelling. Conventional and serial section electron microscopy were used to determine the morphological characteristics of uterine radial arteries from control and pregnant rats. TRPV4 distribution and expression was examined using conventional confocal immunohistochemistry, and the contribution of endothelial TRPV4, nitric oxide (NO) and endothelium-derived hyperpolarization (EDH)-type activity determined using pressure myography with pharmacological intervention. Data show outward hypertrophic remodelling occurs in uterine radial arteries in pregnancy. Further, caveolae density in radial artery endothelium and smooth muscle from pregnant rats was significantly increased by ~94% and ~31%, respectively, compared with control, whereas caveolae density did not differ in endothelium compared with smooth muscle from control. Caveolae density was significantly higher by ~59% on the abluminal compared with the luminal surface of the endothelium in uterine radial artery of pregnant rats but did not differ at those surfaces in control. TRPV4 was present in endothelium and smooth muscle, but not associated with internal elastic lamina hole sites in radial arteries. TRPV4 fluorescence intensity was significantly increased in the endothelium and smooth muscle of radial artery of pregnant compared with control rats by ~2.6- and 5.5-fold, respectively. The TRPV4 signal was significantly higher in the endothelium compared with the smooth muscle in radial artery of both control and pregnant rats, by ~5.7- and 2.7-fold, respectively. Myoendothelial gap junction density was significantly decreased by ~37% in radial artery from pregnant compared with control rats. Pressure myography with pharmacological intervention showed that NO contributes ~80% and ~30%, and the EDH-type component ~20% and ~70% of the total endothelium-dependent vasodilator response in radial arteries of control and pregnant rats, respectively. TRPV4 plays a functional role in radial arteries, with a greater contribution in those from pregnant rats. The correlative association of increased TRPV4 and caveolae density and role of EDH-type activity in uterine radial artery of pregnant rats is suggestive of their causal relationship. The decreased myoendothelial gap junction density and lack of TRPV4 density at such sites is consistent with their having an integral, albeit complex, interactive role in uterine vascular signalling and remodelling in pregnancy.

Oxaliplatin-Induced Damage to the Gastric Innervation: Role in Nausea and Vomiting.

Nausea and vomiting are common gastrointestinal side effects of oxaliplatin chemotherapy used for the treatment of colorectal cancer. However, the mechanism underlying oxaliplatin-induced nausea and vomiting is unknown. The stomach is involved in the emetic reflex but no study investigated the effects of oxaliplatin treatment on the stomach. In this study, the in vivo effects of oxaliplatin treatment on eating behaviour, stomach content, intrinsic gastric neuronal population, extrinsic innervation to the stomach, levels of mucosal serotonin (5-hydroxytryptamine, 5-HT), and parasympathetic vagal efferent nerve activity were analysed. Chronic systemic oxaliplatin treatment in mice resulted in pica, indicated by increased kaolin consumption and a reduction in body weight. Oxaliplatin treatment significantly increased the stomach weight and content. The total number of myenteric and nitric oxide synthase-immunoreactive neurons as well as the density of sympathetic, parasympathetic, and sensory fibres in the stomach were decreased significantly with oxaliplatin treatment. Oxaliplatin treatment significantly increased the levels in mucosal 5-HT and the number of enterochromaffin-like cells. Chronic oxaliplatin treatment also caused a significant increase in the vagal efferent nerve activity. The findings of this study indicate that oxaliplatin exposure has adverse effects on multiple components of gastric innervation, which could be responsible for pica and gastric dysmotility.

Myoendothelial contacts, gap junctions, and microdomains: anatomical links to function?

In several species and in many vascular beds, ultrastructural studies describe close contact sites between the endothelium and smooth muscle of <∼20nm. Such sites are thought to facilitate the local action of signaling molecules and/or the passage of current, as metabolic and electrical coupling conduits between the arterial endothelium and smooth muscle. These sites have the potential for bidirectional communication between the endothelium and smooth muscle, as a key pathway for coordinating vascular function. The aim of this brief review is to summarize the literature on the ultrastructural anatomy and distribution of key components of MECC sites in arteries. In addition to their traditional role of facilitating electrical coupling between the two cell layers, data on the role of MECC sites in arteries, as signaling microdomains involving a spatial localization of channels, receptors and calcium stores are highlighted. Diversity in the density and specific characteristics of MECC sites as signaling microdomains suggests considerable potential for functional diversity within and between arteries in health and disease.

Analysis of the Diversity of Xylophilus ampelinus Strains Held in CIRM-CFBP Reveals a Strongly Homogenous Species.

Xylophilus ampelinus is the causal agent of blight and canker on grapevine. Only a few data are available on this species implying that the occurrence of this pathogen may be underestimated, and its actual ecological niche may not be understood. Moreover, its genetic diversity is not well known. To improve our knowledge of this species, an analysis of the complete genome sequences available in NCBI was performed. It appeared that several sequences are misidentified. The complete genome sequence of the type strain was obtained and primers designed in order to sequence gyrB and rpoD genes for the strains held in CIRM-CFBP. The genetic barcoding data were obtained for 93 strains, isolated over 35 years and from several geographical origins. The species revealed to be strongly homogenous, displaying nearly identical sequences for all strains. However, the oldest strains of this collection were isolated in 2001 therefore, a new isolation campaign and epidemiological surveys are necessary, along with the obtention of new complete genome sequences for this species.

Analysis of real-time serotonin (5-HT) availability during experimental colitis in mouse.

Serotonin (5-HT)-containing enterochromaffin (EC) cells of the intestine transduce chemical and mechanical stimuli from the intestinal lumen by releasing 5-HT on to afferent nerve terminals. Dysfunctional mucosal 5-HT signaling has been implicated in heightened visceral sensitivity and altered motility in patients with inflammatory bowel disease and in animal models. Our aim was to characterize the release and uptake of 5-HT in the mouse dextran sulfate sodium (DSS; 5% wt/vol) model of colitis. We made electrochemical recordings and used an ELISA assay to determine mucosal 5-HT release and uptake in untreated mice and mice with DSS-induced colitis. Peak and steady-state 5-HT concentrations were measured before and during blockade of the serotonin reuptake transporter (SERT) with 1 microM fluoxetine. Electrochemical recordings showed that colons from DSS-treated mice had roughly twice the steady-state levels of extracellular 5-HT and compression-evoked 5-HT release compared with untreated mice. Fluoxetine doubled the compression-evoked and steady-state 5-HT levels in control and DSS mice. These data were supported by ELISA assays, which showed enhanced 5-HT release during colitis, by immunohistochemical analyses, which showed increases in EC cell numbers, and by real-time PCR, which identified a decrease in SERT mRNA expression in the mucosa during colitis. These data are the first to demonstrate 5-HT release close to its release site and near its site of action during DSS-colitis. We conclude that DSS-colitis increases 5-HT availability primarily by an increase in the numbers of EC cells and/or of content of 5-HT in these EC cells.

The Onset and Progression of Chronic Colitis Parallels Increased Mucosal Serotonin Release via Enterochromaffin Cell Hyperplasia and Downregulation of the Serotonin Reuptake Transporter.

Background: Serotonin (5-hydroxytryptamine, 5-HT) has been linked with several inflammation-associated intestinal diseases, including ulcerative colitis (UC). The largest pool of 5-HT in the body is in enterochromaffin (EC) cells located throughout the intestinal tract. EC cells are mechanosensitive and detect noxious stimuli, inducing secretion of 5-HT, which plays an important role in enteric reflexes and immunomodulation. In this study, we evaluated intestinal 5-HT levels in the Winnie mouse model of spontaneous chronic colitis, which closely replicates UC. Methods: Real-time electrochemical recordings of 5-HT oxidation currents were obtained from ex vivo preparations of jejunum, ileum, proximal, and distal colon from Winnie (5-25 weeks old) and age matched C57BL/6 mice. EC cells were examined by immunohistochemistry, and the gene expression of tryptophan hydroxylase 1 (5-HT synthesis) and the serotonin reuptake transporter (SERT) were determined by quantitative Real-Time Polymerase Chain Reaction (RT-qPCR). Results: Compression-evoked and basal 5-HT concentrations were elevated in the distal and proximal colon of Winnie mice. EC cell hyperplasia and downregulation of SERT on the transcriptional level were identified as mechanisms underlying increased levels of 5-HT. Increase in mucosal 5-HT release was observed at the onset of disease at 7-14 weeks, confirmed by disease activity scores. Furthermore, increases in 5-HT levels and progression of disease activity correlated linearly with age, but not sex. Conclusions: Our findings in the Winnie mouse model of spontaneous chronic colitis demonstrate for the first time that the onset and progression of chronic UC-like intestinal inflammation is associated with increased 5-HT levels in the colonic mucosa.

Blockade of Pannexin-1 Channels and Purinergic P2X7 Receptors Shows Protective Effects Against Cytokines-Induced Colitis of Human Colonic Mucosa.

Introduction: The pannexin-1 (Panx1) channels are found in many cell types, and ATP released from these channels can act on nearby cells activating purinergic P2X7 receptors (P2X7R) which lead to inflammation. Although Panx1 and P2X7R are implicated in the process of inflammation and cell death, few studies have looked at the role they play in inflammatory bowel disease in human. Hence, the aim of the present study was to investigate the function of Panx1 and P2X7R in an ex vivo colitis model developed from human colonic mucosal explants. Materials and Methods: Healthy human colonic mucosal strips (4 × 10 mm) were incubated in carbogenated culture medium at 37°C for 16 h. Proinflammatory cytokines TNFα and IL-1ß (each 10 ng/mL) were used to induce colitis in mucosal strips, and the effects of Panx1 and P2X7R on cytokines-induced tissue damage were determined in the presence of the Panx1 channel blocker 10Panx1 (100 µM) and P2X7R antagonist A438079 (100 µM). The effects of 10Panx1 and A438079 on cytokines-enhanced epithelial permeability were also studied using Caco-2 cells. Results: Histological staining showed that the mucosal strips had severe structural damage in the cytokines-only group but not in the incubation-control group (P < 0.01). Compared to the cytokines-only group, crypt damage was significantly decreased in groups receiving cytokines with inhibitors (10Panx1, A438079, or 10Panx1 + A438079, P < 0.05). The immunoreactive signals of tight junction protein zonula occludens-1 (ZO-1) were abundant in all control tissues but were significantly disrupted and lost in the cytokines-only group (P < 0.01). The diminished ZO-1 immunoreactivity induced by cytokines was prevented in the presence of 10Panx1 (P = 0.04). Likewise, 10Panx1 significantly attenuated the cytokines-evoked increase in paracellular permeability of Caco-2 cells. Although the inhibition of P2X7R activity by A438079 diminished cytokines-induced crypt damage, its effect on the maintenance of ZO-1 immunoreactivity and Caco-2 epithelial cell integrity was less evident. Conclusion: The blockade of Panx1 and P2X7R reduced the inflammatory cytokines-induced crypt damage, loss of tight junctions and increase in cell permeability. Thus, Panx1 and P2X7R may have roles in causing mucosal damage, a common clinical feature of inflammatory bowel disease.

Esophageal Dysmotility in Patients following Total Laryngectomy.

Objectives Dysphagia is common in total laryngectomees, with some symptoms suggesting esophageal dysmotility. Tracheoesophageal (TE) phonation requires effective esophagopharyngeal air passage. Hence, esophageal dysmotility may affect deglutition or TE phonation. This study aimed to determine (1) the characteristics of esophageal dysmotility in laryngectomees, (2) whether clinical history is sensitive in detecting esophageal dysmotility, and (3) the relationship between esophageal dysmotility and TE prosthesis dysfunction. Study Design Multidisciplinary cross-sectional study. Setting Tertiary academic hospital. Subjects and Methods For 31 participants undergone total laryngectomy 1 to 12 years prior, clinical histories were taken by a gastroenterologist and a speech pathologist experienced in managing dysphagia. Esophageal high-resolution manometry was performed and analyzed using Chicago Classification v3.0. Results Interpretable manometric studies were obtained in 23 (1 normal manometry). Esophageal dysmotility patterns included achalasia, esophagogastric junction outflow obstruction, diffuse esophageal spasm, and other major (30%) and minor (50%) peristaltic disorders. The sensitivity of predicting any esophageal dysmotility was 28%, but it is noteworthy that patients with achalasia and diffuse esophageal spasm (DES) were predicted. Two of 4 participants with TE puncture leakage had poor esophageal clearance. Of 20 TE speakers, 12 had voice problems, no correlation between poor voice, and any dysmotility pattern. Conclusions Peristaltic and lower esophageal sphincter dysfunction are common in laryngectomees. Clinical history, while not predictive of minor motor abnormalities, predicted correctly cases with treatable spastic motor disorders. Dysmotility was not associated with poor phonation, although TE puncture leakage might be linked to poor esophageal clearance. Esophageal dysmotility should be considered in the laryngectomees with persisting dysphagia or leaking TE puncture.

Teaching basic gastrointestinal physiology using classic papers by Dr. Walter B. Cannon.

The movements of the gastrointestinal tract, as described by Walter B. Cannon 100 years ago, reveal much about the functions of this unique organ and how it is controlled by the body. Two classic papers by Cannon provide a rare glimpse into the hidden functions of the body and give students a great example of the scientific method in action. In this essay, we describe the basic movements and functions of the gastrointestinal tract as revealed by X-rays, contrast meals, and Cannon's careful observations. It is Cannon's experimental care and obvious interest in his subject matter that can provide your students with a taste of the excitement of discovery and insight into the processes by which experimental science moves forward.

Purinergic Signaling in Gut Inflammation: The Role of Connexins and Pannexins.

Purinergic receptors play an important role in inflammation, and can be activated by ATP released via pannexin channels and/or connexin hemichannels. The purinergic P2X7 receptor (P2X7R) is of interest since it is involved in apoptosis when activated. Most studies focus on the influence of pannexin-1 (Panx1) and connexin 43 (Cx43) on ATP release and how it affects P2X7R function during inflammation. Inflammatory bowel disease (IBD) is characterized by uncontrolled inflammation within the gastrointestinal system. At present, the pathophysiology of this disease remains largely unknown but it may involve the interplay between P2X7R, Panx1, and Cx43. There are two main types of IBD, ulcerative colitis and Crohn's disease, that are classified by their location and frequency of inflammation. Current research suggests that alterations to normal functioning of innate and adaptive immunity may be a factor in disease progression. The involvement of purinergic receptors, connexins, and pannexins in IBD is a relatively novel notion in the context of gastrointestinal inflammation, and has been explored by various research groups. Thus, the present review focuses on the current research involving connexins, pannexins, and purinergic receptors within the gut and enteric nervous system, and will examine their involvement in inflammation and the pathophysiology of IBD.

Biomechanics of Pharyngeal Deglutitive Function following Total Laryngectomy.

OBJECTIVE: Postlaryngectomy, pharyngeal weakness, and pharyngoesophageal junction (PEJ) restriction are the candidate mechanisms of dysphagia. The aims were, in laryngectomees, whether (1) hypopharyngeal propulsion is reduced and/or PEJ resistance is increased, (2) dilatation improves dysphagia, and (3) whether symptomatic improvement correlates with reduced PEJ resistance. DESIGN: Multidisciplinary cross-sectional study. SETTING: Tertiary academic hospital. SUBJECTS AND METHODS: Swallow biomechanics were assessed in 30 laryngectomees. Patients were stratified into severe dysphagia (Sydney Swallow Questionnaire >500) and mild/nil dysphagia (Sydney Swallow Questionnaire ≤500). Average hypopharyngeal peak (contractile) pressure (hPP) and hypopharyngeal intrabolus pressure (hIBP) were measured from high-resolution manometry with concurrent videofluoroscopy based on barium swallows (2.5 and 10 mL). In consecutive 5 patients, measurements were repeated after dilatation. RESULTS: Dysphagia was reported by 87%, and 57% had severe and 43% had mild/nil dysphagia. hIBP increased with larger bolus volumes (P < .0001), while hPP stayed stable and PEJ diameter plateaued at 9 mm. Laryngectomees had lower hPP (110 ± 14 vs 170 ± 15 mm Hg; P = .0162) and higher hIBP (29 ± 5 vs 6 ± 5 mm Hg; P = .156) than controls. There were no differences in hPP between patient groups. However, hIBP was higher in severe than in mild/nil dysphagia (41 ± 10 vs 13 ± 3 mm Hg; P = .02). Predilation hIBP (R(2) = 0.97) and its decrement postdilatation (R(2) = 0.98) well predicted symptomatic improvement. CONCLUSIONS: PEJ resistance correlates better with dysphagia severity than peak pharyngeal pressure and is more sensitive to bolus sizes than PEJ diameter. Both baseline PEJ resistance and its decrement following dilatation are strong predictors of treatment outcome. PEJ resistance is vital to detect, as it is reversible and can predict the response to dilatation regimens.