High-flow nasal oxygen does not increase the volume of gastric secretions during spontaneous ventilation.

BACKGROUND: High-flow, heated, and humidified nasal oxygen therapy (HFNO) is frequently used in critical care and perioperative settings for a range of clinical applications. Much of the benefit of HFNO is attributed to generation of modest levels of positive airway pressure. Concern has been raised that this positive airway pressure may cause gastric insufflation, potentially increasing the risk of regurgitation and aspiration in an unprotected airway. METHODS: A prospective, interventional, assessor-blinded study was undertaken to evaluate the effects of HFNO on gastric content and gastric distension in healthy fasted adult volunteers assessed by ultrasonography. The primary outcome was the volume of gastric secretions. The secondary outcomes were the incidence of gastric air insufflation and the distribution of gastric antral grades. RESULTS: Sixty subjects were enrolled. No subject was found to have air gastric distension either at baseline or after treatment with HFNO. All subjects had either a Grade 0 or Grade 1 antrum, with similar distribution of antral grades and similar volume of gastric secretions before and after treatment with HFNO. CONCLUSIONS: There was no evidence that treatment with HFNO at flow rates of up to 70 L min-1 for 30 min resulted in gastric distension or an increase in gastric secretions in healthy individuals breathing spontaneously. The generalisability of these findings to subjects under anaesthesia and patients with incompetence of the lower oesophageal sphincter or impaired gastric emptying requires further investigation. CLINICAL TRIAL REGISTRATION: NCT03134937.

A standardised semi-dynamic in vitro digestion method suitable for food - an international consensus.

The link between food and human health is increasingly a topic of interest. One avenue of study has been to assess food disintegration and interactions within the gastrointestinal tract. In vitro digestion models have been widely used to overcome the constrictions associated with in vivo methodology. The COST Action INFOGEST developed an international, harmonised protocol for static simulation of digestion in the upper gastrointestinal tract of adults. This protocol is widely used; however, it is restricted to providing end-point assessment without considering the possible structural changes. On the other hand, there are dynamic models that provide more physiologically relevant data but are expensive and difficult to access. There is a gap between these models. The method outlined in this article provides an intermediate model; it builds upon the harmonised static model and now includes crucial kinetic aspects associated with the gastric phase of digestion, including gradual acidification, fluid and enzyme secretion and emptying. This paper provides guidance and standardised recommendations of a physiologically relevant semi-dynamic in vitro simulation of upper gastrointestinal tract digestion, with particular focus on the gastric phase. Adaptations of this model have already been used to provide kinetic data on nutrient digestion and structural changes during the gastric phase that impact on nutrient absorption. Moreover, it provides a simple tool that can be used in a wide range of laboratories.

Isolation, characterization, and assessment of lactic acid bacteria toward their selection as poultry probiotics.

BACKGROUND: Probiotics are live microorganisms that, when administered in adequate amounts, confer a health benefit on the host, are now accepted as suitable alternatives to antibiotics in the control of animal infections and improving animal production. Lactic acid bacteria (LAB) with remarkable functional properties have been evaluated in different studies as possible probiotic candidates. The purpose of this study was to isolate, characterize and assess the potentials of LAB from poultry gastrointestinal tract as potential poultry probiotics. RESULTS: Potential LAB probiotics were isolated from broilers, characterized and evaluated for probiotic properties including antagonistic activity (against Escherichia coli, E. coli O157: H7, Enterococcus faecalis, Salmonella Typhimurium, S. Enteritidis and Listeria monocytogenes), survivability in simulated gastric juice, tolerance to phenol and bile salts, adhesion to ileum epithelial cells, auto and co-aggregation, hydrophobicity, α-glucosidase inhibitory activity, and antibiotic susceptibility tests. Most promising LAB strains with excellent probiotic potentials were identified by API 50 CHL and 16S rRNA sequencing as Lactobacillus reuteri I2, Pediococcus acidilactici I5, P. acidilactici I8, P. acidilactici c3, P. pentosaceus I13, and Enterococcus faecium c14. They inhibited all the pathogens tested with zones of inhibition ranging from 12.5 ± 0.71 to 20 ± 0 mm, and competitively excluded (P < 0.05) the pathogens examined while adhering to ileum epithelial cells with viable counts of 3.0 to 6.0 Log CFU/ml. The selected LAB strains also showed significant (P < 0.005) auto and co-aggregation abilities with α-glucosidase inhibitory activity ranging from 12.5 to 92.0%. The antibiotic susceptibility test showed 100.00% resistance of the LAB strains to oxacillin, with multiple antibiotic resistance indices above 0.5. CONCLUSION: The selected LAB strains are ideal probiotic candidates which can be applied in the field for the improvement of poultry performance and control of pathogens in poultry, hence curtailing further transmission to humans.

In vitro digestion models to assess lipolysis: The impact of the simulated conditions of gastric and intestinal pH, bile salts and digestive fluids.

In vitro digestion models are a valid methodology to study nutrient hydrolysis by simulating standard physiological gastrointestinal conditions. However, there are pathologies in which some conditions are affected, which should be considered in the design of an in vitro digestion study. Our work aims at elucidating the role of different gastrointestinal conditions on lipolysis. In the context of exocrine pancreatic insufficiency, gastric pH, intestinal pH, bile salts composition, bile salts concentration, fat concentration in the digestion medium and volumetric ratio digestion fluid/food were the selected study parameters. The pH-stat method was applied to assess lipolysis extent and kinetics. Descriptive results were summarised in digestibility curves and beta regression models were used to explain the effect (odds ratio, OR) of the studied conditions on lipolysis. Additionally, distribution of emulsion droplets was measured and optical microscopy images of fat globules were taken in a selection of experimental conditions. Results showed that intestinal pH was the variable with the highest effect on lipolysis (OR 22.86, p < 0.001), followed by fat concentration in the digestion medium (OR 6.76, p < 0.001) and bile salts concentration (OR 1.56, p < 0.001). Overall, lipolysis was significantly associated with particle size (OR - 6.98, p < 0.001). We conclude that the assessment of lipolysis by means of in vitro digestion models is sensitive to the simulated gastrointestinal conditions, which should be adapted to the real physiological conditions occurring in altered health conditions.

Potential premalignant status of gastric portion excluded after Roux en-Y gastric bypass in obese women: A pilot study.

We evaluated whether the excluded stomach (ES) after Roux-en-Y gastric bypass (RYGB) can represent a premalignant environment. Twenty obese women were prospectively submitted to double-balloon enteroscopy (DBE) with gastric juice and biopsy collection, before and 3 months after RYGB. We then evaluated morphological and molecular changes by combining endoscopic and histopathological analyses with an integrated untargeted metabolomics and transcriptomics multiplatform. Preoperatively, 16 women already presented with gastric histopathological alterations and an increased pH (≥4.0). These gastric abnormalities worsened after RYGB. A 90-fold increase in the concentration of bile acids was found in ES fluid, which also contained other metabolites commonly found in the intestinal environment, urine, and faeces. In addition, 135 genes were differentially expressed in ES tissue. Combined analysis of metabolic and gene expression data suggested that RYGB promoted activation of biological processes involved in local inflammation, bacteria overgrowth, and cell proliferation sustained by genes involved in carcinogenesis. Accumulated fluid in the ES appears to behave as a potential premalignant environment due to worsening inflammation and changing gene expression patterns that are favorable to the development of cancer. Considering that ES may remain for the rest of the patient's life, long-term ES monitoring is therefore recommended for patients undergoing RYGB.

Chewing gum for 1 h does not change gastric volume in healthy fasting subjects. A prospective observational study.

STUDY OBJECTIVE: Perioperative fasting guidelines differ in their approaches to chewing gum in the preoperative period. Current recommendations range from canceling the surgery to proceeding with it. Given this lack of consensus, we performed gastric ultrasound assessments in healthy volunteers before and after a standardized period of chewing gum. The objective of our study was to determine if chewing gum for 1 h change the gastric volume. DESIGN: Observational prospective analytical study. SETTING: Bedside gastric ultrasound. PATIENTS: Following institutional Review Board approval, 55 healthy (American Society of Anesthesiologists class I to II) fasted (non-surgical research) volunteers provided written informed consent to participate in the study. Morbid obesity, renal failure, diabetes mellitus, pregnancy and previous upper abdominal surgery were exclusion criteria. INTERVENTIONS: Volunteers chewed gum for 1 h between the first and second assessment. MEASUREMENTS: Four gastric ultrasound assessments were performed, the first one at baseline and then hourly thereafter. MAIN RESULTS: Fifty-five healthy volunteers were studied. The proportion of subjects who presented a completely empty stomach (Grade 0 antrum) was similar at baseline and after 1 h of gum-chewing [81% vs. 84%, p = 0.19, CI 95% (-12%, 16%)]. Among those subjects who had visible fluid at baseline, the volume remained unchanged throughout the study period. CONCLUSIONS: One hour of gum-chewing had no significant effect on the gastric fluid volume of healthy volunteers, suggesting that it may be safe for healthy subjects to chew gum prior to elective surgery.

The predictive value of hunger score on gastric evacuation after oral intake of carbohydrate solution.

BACKGROUND: Surgical patients are asked to fast for a sufficient duration to ensure that the amount of residual liquid in the stomach is within the safe range, thereby reducing the risk of gastric reflux perioperatively. The authors hypothesized that subjective hunger numerical rating scale (NRS) score could also help assess the process of gastric emptying and determine the amount of fluid remaining in the stomach. METHODS: The current study consisted of healthy volunteers recruited by advertisement and mutual introduction. Participants were asked to rate their subjective hunger feeling every 30 min after oral administration of 8 mL/kg carbohydrate nutrient solution that contained 10% maltodextrin and 2.5% sucrose. Consecutively, the gastric residual fluid was measured by magnetic resonance imagining (MRI). The Spearman's correlation coefficient, the ROC curves and the stepwise regression were used to analyze the predictive value of NRS for the gastric emptying process. RESULTS: The cohort consisted of 29 healthy volunteers enrolled in this study. The area under ROC curves estimated by the NRS score for the gastric residual volume of 2 mL/kg, 1 mL/kg, and 0.5 mL/kg were AUC2.0 = 0.78, AUC1.0 = 0.76, and AUC0.5 = 0.72, respectively. The correlation coefficient between the NRS score and the residual liquid in the stomach was -0.57 (P < 0.01). The correlation coefficient between the increase of the NRS score and the decrease of gastric liquid residual volume was 0.46 (P < 0.01). The standardized estimate of NRS score for the residual volume was -0.18 (P < 0.01) and the standardized estimate of fasting time was -0.73 (P < 0.01). CONCLUSIONS: The subjective hunger NRS score can not accurately predict the gastric residual volume, but it can provide a reference for clinicians to judge the gastric emptying process and it should be used as a second check after oral intake of clear fluids before surgery according to the new fasting protocol.

Pathophysiology of Gastroesophageal Reflux Disease.

The pathogenesis of gastroesophageal reflux disease (GERD) is complex and involves changes in reflux exposure, epithelial resistance, and visceral sensitivity. The gastric refluxate is a noxious material that injures the esophagus and elicits symptoms. Esophageal exposure to gastric refluxate is the primary determinant of disease severity. This exposure arises via compromise of the anti-reflux barrier and reduced ability of the esophagus to clear and buffer the refluxate, leading to reflux disease. However, complications and symptoms also occur in the context of normal reflux burden, when there is either poor epithelial resistance or increased visceral sensitivity. Reflux therefore develops via alterations in the balance of aggressive and defensive forces.

Geometric Mixing, Peristalsis, and the Geometric Phase of the Stomach.

Mixing fluid in a container at low Reynolds number--in an inertialess environment--is not a trivial task. Reciprocating motions merely lead to cycles of mixing and unmixing, so continuous rotation, as used in many technological applications, would appear to be necessary. However, there is another solution: movement of the walls in a cyclical fashion to introduce a geometric phase. We show using journal-bearing flow as a model that such geometric mixing is a general tool for using deformable boundaries that return to the same position to mix fluid at low Reynolds number. We then simulate a biological example: we show that mixing in the stomach functions because of the "belly phase," peristaltic movement of the walls in a cyclical fashion introduces a geometric phase that avoids unmixing.

Intrinsic causes of erosion.

Gastric juice entering the mouth causes dental erosion. Common causes for the migration of gastric juice through the lower and upper oesophageal sphincters are reflux disease, laryngopharyngeal reflux, eating disorders, chronic alcoholism and pregnancy. Gastroesophageal reflux is a common condition affecting up to 65% of the Western population at some point in their lifetime. A typical clinical sign of acidic gastric juice entering the mouth is palatal dental erosion. As the condition becomes more chronic it becomes more widespread. There have been relatively few randomised studies investigating the aetiology of acids causing erosion. Of the few that have reported their findings, it appears that gastric acids have the potential to induce moderate-to-severe erosion. This literature review reports the conditions associated with the movement of gastric juice and dental erosion using medical and dental sources.

Modelo de instilación intra-traqueal de jugo gástrico en la rata: curso temporal de las alteraciones histológicas / Intra-tracheal instillation of gastric juice in the rat: time course of histological changes

Introduction: Aspiration of gastric content is associated with a wide range of clinical conditions (acute lung injury, severe interstitial pneumonia or bronchiolitis obliterans following lung transplantation). Objective: To study the course of histological alterations in a model of intra-tracheal instillation of gastric juice in rats. Methods: Anesthetized rats were euthanized at different times: 4, 12 and 24 hours and 4 and 7 days after intratacheal (IT) instillation of gastric juice. Animals that were not intervened served as controls. The right inferior lobe was studied (H-E) and a histological injury score was given according to a recently published score system. Results: Between 4-24 h an inflammatory-hemorragic pattern with bronchiol-centric distribution was characterized by a large proportion of neutrophils in both alveoli and interstitium, alveolarfluid accumulation, proteinaceous material andfew hyaline membranes. Between 4 and 7 days, mononuclear cells were more prevalent, the hemorrhagic component disappeared, the percentage of abnormal bronchioles was significantly reduced and there was organization of the alveolar infiltrate, with Masson bodies, granulomas and giant cells associated with gastric juice particles. Conclusions: In rats, IT instillation of gastric juice induces diffuse alveolar damage that evolves towards an early granulomatous interstitial pneumonia along with lax fibrous tissue. Knowledge of the temporary course of the pulmonary responses helps to the understanding of the consequences of the several clinical conditions that favor gastric content aspiration.

Introducción: La aspiración de contenido gástrico se asocia con diversas condiciones clínicas (daño pulmonar agudo, neumonía intersticial severa o bronquiolitis obliterante post-trasplante). Objetivo: Estudiar el curso de las alteraciones histológicas en un modelo de instilación intra-traqueal (IT)de jugo gástrico en ratas. Métodos: Ratas anestesiadas recibieron vía ITjugo gástrico de un pool obtenido previamente. Los animales fueron sacrificados a las: 4, 12 y 24 h y 4 y 7 días post-instilación. Animales sin intervención sirvieron como controles. El lóbulo inferior derecho fue estudiado (H-E) para la asignación de un puntaje de daño histológico de acuerdo a un sistema de puntuación recientemente publicado. Resultados: Entre 4-24 h se observó un patrón inflamatorio-hemorrágico de distribución bronquíolo-céntrica, con predominio de neutrófilos intersticiales y alveolares, edema, material proteináceo alveolar y escasas membranas hialinas. Entre los 4 y 7 días, se observó predominio mononuclear y desaparición del componente hemorrágico, se redujo significativamente el porcentaje de bronquíolos afectados y se observó organización del infiltrado inflamatorio, con cuerpos de Masson, granulomas y células gigantes asociadas a partículas del jugo gástrico. Conclusiones: En ratas, la instilación IT de jugo gástrico induce daño alveolar difuso que progresa hacia una neumonía intersticial granulo-matosa temprana con tejido fibroso laxo. El conocimiento del curso de la respuesta pulmonar en este modelo, contribuye a comprender las posibles consecuencias de las condiciones clínicas que favorecen la aspiración de contenido gástrico.

Hyperspectroscopic imager for baby fibers.

Hyperspectral imaging system for diagnosing digestive diseases was newly developed in order to obtain information on pathology beyond morphology of lesions. In order to guide light reflected from a lesion, a baby fiber, which can be inserted in a forceps channel of the electronic endoscope, was also developed. The performance of the system was evaluated by animal experiment. Obtained hyperspectral data were found to have sufficient quality endurable to practical use. Harmful phenomena to a living body were not observed within the experiment. It was considered from the animal experiment that the present system could be practically used for humans.

Characterization of fasted human gastric fluid for relevant rheological parameters and gastric lipase activities.

PURPOSE: To characterize human gastric fluid with regard to rheological properties and gastric lipase activity. In addition, traditional physicochemical properties were determined. METHODS: Fasted HGA were collected from 19 healthy volunteers during a gastroscopic examination. Rheological characterization of the aspirates was conducted on a TA AR-G2 rheometer, using cone and plate geometry. Lipase activity was measured by continuous titration of released free fatty acid from tributyrate. Further, pH, osmolality, buffer capacity, and surface tension were measured and the total protein content and bile salt level were determined using assay kits. RESULTS: Rheological examination of HGA showed non-Newtonian shear-thinning behavior with predominant elastic behavior in the linear range. The apparent viscosity was measured to be in the range of 1.7-9.3 mPas at a shear rate of 50s(-1). The FaSSGF and HCl pH 1.2 have no shear-thinning properties and showed lower viscosity (1.1 mPas at 50 s(-1)). The observed viscosity of the HGA will decrease the intrinsic dissolution rate of drugs. The activity of the gastric lipase was 7.4 ± 4.0 U/mL (N = 6, n = 3) and 99.0 ± 45.3 U/mL (N = 19, n = 3) at pH 2.8 and 5.4, respectively. pH, surface tension, buffer capacity, bile salt concentration, and osmolality were measured and compared with literature data. CONCLUSION: The rheological behavior and the mean apparent viscosity of HGA are significantly different from that of water and should therefore be considered important during development of gastric simulated media. Further, the activity of the HGL is active even under fasted gastric conditions and might contribute to the digestion and emulsification of lipid-based drug delivery systems in the entire gastrointestinal tract. HGL should therefore be considered in gastric evaluation of lipid-based drug delivery systems.

The effect of gastric juice on interleukin-8 production by cystic fibrosis primary bronchial epithelial cells.

UNLABELLED: CF patients are often treated with proton pump inhibitors (PPIs) to reduce acidic gastro-esophageal reflux (GER) and bronchial aspiration of duodeno-gastric contents is common in CF. We have previously demonstrated that gastric juice (GJ) from patients "on" PPI can induce interleukin-8 (IL-8) production by bronchial epithelial cells in culture. We hypothesized that such effect would be more pronounced in CF patients known to have high inflammatory susceptibility. We aimed to evaluate the effect of GJ on IL-8 production by primary bronchial epithelial cells (PBEC), derived from a CF patient and a healthy subject. METHODS: PBEC obtained from one donor (normal PBEC) and one receptor (CF-PBEC) for lung transplantation were stimulated with GJ from patients "off" and "on" PPI. IL-8 levels were measured in the supernatant. RESULTS: GJ from patients "on" PPI provoked a significant higher IL-8 production compared to GJ from patients "off" PPI, both in normal PBEC [462 (200-1468) vs. 11 (4-28) pg/ml, p=0.0001] as in CF-PBEC [1468 (841-2449) vs. 85 (26-131) pg/ml, p<0.0001]. Exposure of the cells to GJ "off" PPI and "on" PPI provoked significantly higher IL-8 production in the CF-PBEC compared to the normal PBEC ["off" PPI 85 (26-131) vs. 11 (4-28) pg/ml, p=0.01; "on" PPI 1468 (841-2449) vs. 462 (200-1468) pg/ml, p=0.01]. Filtration (0.20 µm) of the GJ "on" PPI, to eliminate large particles and bacterial sub-products, resulted in a significant decrease of IL-8 production. CONCLUSION: Patients with CF, treated with PPIs, have GJ with high pH and high endotoxin levels. These patients often have GER and bronchial aspiration. The aspirated material (GJ "on" PPI) has a significantly enhanced inflammatory effect on CF bronchial epithelial cells in culture. As chronic PPI treatment in CF may result in a paradoxically increased inflammatory effect in the airways, alternative anti-reflux therapies should be considered in CF.

Physiological roles of dietary glutamate signaling via gut-brain axis due to efficient digestion and absorption.

Dietary glutamate (Glu) stimulates to evoke the umami taste, one of the five basic tastes, enhancing food palatability. But it is also the main gut energy source for the absorption and metabolism for each nutrient, thus, only a trace amount of Glu reaches the general circulation. Recently, we demonstrated a unique gut sensing system for free Glu (glutamate signaling). Glu is the only nutrient among amino acids, sugars and electrolytes that activates rat gastric vagal afferents from the luminal side specifically via metabotropic Glu receptors type 1 on mucosal cells releasing mucin and nitrite mono-oxide (NO), then NO stimulates serotonin (5HT) release at the enterochromaffin cell. Finally released 5HT stimulates 5HT3 receptor at the nerve end of the vagal afferent fiber. Functional magnetic resonance imaging (f-MRI, 4.7 T) analysis revealed that luminal sensing with 1 % (w/v) monosodium L-glutamate (MSG) in rat stomach activates both the medial preoptic area (body temperature controller) and the dorsomedial hypothalamus (basic metabolic regulator), resulting in diet-induced thermogenesis during mealing without changes of appetite for food. Interestingly, rats were forced to eat a high fat and high sugar diet with free access to 1 % (w/w) MSG and water in a choice paradigm and showed the strong preference for the MSG solution and subsequently, they displayed lower fat deposition, weight gain and blood leptin. On the other hand, these brain functional changes by the f-MRI signal after 60 mM MSG intubation into the stomach was abolished in the case of total vagotomized rats, suggesting that luminal glutamate signaling contributes to control digestion and thermogenesis without obesity.

Use of a continuous leaching method to assess the oral bioaccessibility of trace elements in seafood.

A continuous leaching method, coupled online with inductively coupled plasma mass spectrometry (ICP-MS) was used on seafood samples to assess the maximum bioaccessibility of several trace elements. The method indeed involves continuous leaching of the food sample by artificial saliva and gastric juice, successively, where this exposition of the food to fresh reagent drives the dissolution equilibrium to the right. Leaching with intestinal juice had to be omitted because it resulted in clogging problems. The experimental apparatus includes a mini-column of powdered sample, which is directly connected to the nebulizer of an ICP-MS instrument. The on-line approach allows a quick assessment of the maximum bioaccessibility of elements of interest by monitoring the real-time release of elements by a given reagent. The method was applied to determine the bioaccessibility of four toxic elements (Al, Cd, Hg, and Pb) and of four essential elements (V, Mn, Cu, and Zn) in certified reference materials and in actual seafood samples. In all cases, mass balance was verified by carrying out the total digestion of the remaining residue from the mini-column and the relationship between total concentration and bioaccessibility was examined.

The prebiotic source influences the growth, biochemical features and survival under simulated gastrointestinal conditions of the probiotic Lactobacillus acidophilus.

The viability of the probiotic strain Lactobacillus acidophilus DSM 20079, after its passage through the simulated gastric and pancreatic juices, was evaluated as function of its pre-growth in a medium containing the known prebiotics pectin or inulin, and was compared to glucose used as control. The presence of pectin or inulin did not affect the growth (12.11(log10) colony forming units/mL and 12.08(log10) colony forming units/mL for pectin and inulin respectively versus 12.22(log10) colony forming units/mL obtained for glucose). Pectin and inulin, in contrast to glucose, induced cell stress resistance against gastrointestinal juices (Δ(log10) 1 and 2 colony forming units/mL respectively, versus Δ(log10) 4.5 for glucose). The data were confirmed by the analysis of the protein pattern following stress treatments which, in the case of microbial cells grown with glucose, revealed a relevant protein degradation after the double passage through simulated gastric and intestinal juices. An impressive metabolic change, as function of the growth conditions, was demonstrated by analyzing the proteomic profile with a µ-2DE system, used herein for the first time as evaluation tool of prebiotic-probiotic interactions. The analysis revealed a different pH protein distribution that was mostly acidic in the presence of pectin and neutral-alkaline in the presence of inulin. Both prebiotics stimulated the production of butyrate, a relevant healthy bio-molecule not detectable in the presence of glucose, that was measured by HPLC analysis to be 14.5 fold higher after growth in the presence of inulin, as compared to pectin. Three specific proteins were detected at pH 6 after growth in the presence of pectin or inulin. They could be correlated to the stress resistance and/or to the production of butyrate, the common phenotypic characteristics induced in the bacterial strain by the two prebiotics.