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Introduction and Aims: Helicobacter pylori (H. pylori) is associated with a higher risk of peptic ulcer and gastric cancer. The sole presence of the bacterium is not a determinant of clinical outcome, but rather the interaction of strain type and host factors determines the risk of disease. Our aim was to study the association between bacterial load, strain type, and gastric symptoms in H. pylori-positive subjects., Materials and Methods: In a community survey, a diagnostic 13 C-urea breath test for H. pylori was performed on 302 volunteers that were not taking antibiotics, antacids, or proton pump inhibitors one month prior to the test. The breath test produced 25 H. pylori-positive subjects, between 25-74 years of age, who then took a gastric symptoms survey and were tested for the presence of the cagA genotype in gastric juice, using the Entero-test®. Bacterial load was determined as a measure of urease activity, utilizing the delta over baseline value, obtained in the 13 C-urea breath test., Results: A total of 48% of the H. pylori-positive subjects were cagA+. A positive association was found between cagA status and high gastric urease activity (P<.0001) and the latter was significantly associated with the presence of symptoms (P<.0001)., Conclusion: Gastric urease activity was strongly associated with dyspeptic symptoms and cagA+ H. pylori. Elevated 13 C-delta over baseline values could be used as indicators of a higher risk for gastric disease., (Copyright © 2020 Asociación Mexicana de Gastroenterología. Publicado por Masson Doyma México S.A. All rights reserved.)

Developing a mechanistic understanding of the impact of food structure and composition on human health has increasingly involved simulating digestion in the upper gastrointestinal tract. These simulations have used a wide range of different conditions that often have very little physiological relevance, and this impedes the meaningful comparison of results. The standardized protocol presented here is based on an international consensus developed by the COST INFOGEST network. The method is designed to be used with standard laboratory equipment and requires limited experience to encourage a wide range of researchers to adopt it. It is a static digestion method that uses constant ratios of meal to digestive fluids and a constant pH for each step of digestion. This makes the method simple to use but not suitable for simulating digestion kinetics. Using this method, food samples are subjected to sequential oral, gastric and intestinal digestion while parameters such as electrolytes, enzymes, bile, dilution, pH and time of digestion are based on available physiological data. This amended and improved digestion method (INFOGEST 2.0) avoids challenges associated with the original method, such as the inclusion of the oral phase and the use of gastric lipase. The method can be used to assess the endpoints resulting from digestion of foods by analyzing the digestion products (e.g., peptides/amino acids, fatty acids, simple sugars) and evaluating the release of micronutrients from the food matrix. The whole protocol can be completed in ~7 d, including ~5 d required for the determination of enzyme activities.

In the present study, structural changes in the milk protein α-lactalbumin (α-LA) and its proteolysis were investigated for the potential formation of protein-fatty acid complexes during in vivo gastric digestion. Capsule endoscopy allowed visualisation of the digestion of the test drinks, with nasogastric tubes allowing sampling of the gastric contents. A total of ten healthy volunteers had nasogastric tubes inserted into the stomach and ingested test drinks containing 50 g/l of sucrose and 25 g/l of α-LA with and without 4 g/l of oleic acid (OA). The samples of gastric contents were collected for analysis at 3 min intervals. The results revealed a rapid decrease in the pH of the stomach of the subjects. The fasting pH of 2·31 (SD 1·19) increased to a pH maxima of pH 6·54 (SD 0·29) after ingestion, with a subsequent decrease to pH 2·22 (SD 1·91) after 21 min (n 8). Fluorescence spectroscopy and Fourier transform IR spectroscopy revealed partial protein unfolding, coinciding with the decrease in pH below the isoelectric point of α-LA. The activity of pepsin in the fasting state was found to be 39 (SD 12) units/ml of gastric juice. Rapid digestion of the protein occurred: after 15 min, no native protein was detected using SDS-PAGE; HPLC revealed the presence of small amounts of native protein after 24 min of gastric digestion. Mirocam® capsule endoscopy imaging and video clips (see the online supplementary material) revealed that gastric peristalsis resulted in a heterogeneous mixture during gastric digestion. Unfolding of α-LA was observed during gastric transit; however, there was no evidence of a cytotoxic complex being formed between α-LA and OA.

By the levels of stomach juice volume, its proteolytic activity, hydrogen ion activity, secreted mucus volume, the experimental dogs with stomach fistula were divided into two groups: with low and with high levels of secretion. The perturbing effects involved immobilization stress, mineral water, prolin-containing peptide Gly-Pro. One of the self-regulation mechanisms involved an "initial background rule": if the initial level of the secretion parameters is low, then it grows following the effect, whereas if it is high--it becomes lower. The rule was most evident in the stomach juice secretion complex-reflex phase.

Background and Aims: Orlistat, a lipase inhibitor, strongly inhibits the activities of all gastric/pancreatic lipases except pancreatic phospholipase A(2)in vitro. In clinical use, for obesity treatment, it induces a variable degree of weight loss and steatorrhoéa. The aim of this study was to examine the degree of in vivo inhibition of individual gastric/pancreatic lipases by Orlistat in man, when given as a capsule or mixed into a test meal in the form of an optimal substrate for the lipases., Methods: Twelve male volunteers were intubated twice with a triple lumen nasal-gastric-duodenal tube and were given a balanced test meal with or without 60 mg Orlistat. Three conditions were compared: (a) Orlistat given as a capsule with the meal, (b) Orlistat mixed into the test meal before ingestion, and (c) test meal without Orlistat. Samples were collected at six 30 min intervals, from stomach, mid-duodenum, and ligament of TreitY. Activities and immune-reactive masses of gastric lipase, pancreatic lipase, carboxyl ester lipase, colipase, and mass of non-polar lipid classes were determined., Results: In vivo effects on the enzyme activities were more pronounced when Orlistat was mixed with the meal than when given as a capsule (7%, 10%, 1% vs 49%, 54%, 34% of normal activity), respectively. Despite efficient inhibition of the lipases, an extensive hydrolysis of the emulsified lipids of the test meal occurred. Orlistat did not affect the immune-reactive amounts of lipases., Conclusions: Orlistat causes a pronounced in vivo inhibition of gastric and pancreatic lipases in humans. The mixing with the substrate and the fact that little residual lipase activity is necessary to hydrolyse optimally emulsified lipids are likely to be limiting factors for the effect of the drug in clinical practice.

Procolipase was identified in the stomach by in situ hybridisation. A strong autoradiographic labelling of chief cells was seen in the fundus region, declining more distally and being almost absent in antrum. There was no labelling seen in the intestine. Colipase activity was estimated in rat gastric juice following pentagastrin stimulation and was found to average 2 microM. Furthermore, enterostatin, the N-terminal pentapeptide of procolipase, has been identified in the rat gut and pancreas. Extracts from gastric mucosa, intestinal mucosa and pancreas were purified by gel filtration (Sephadex G25), ion-exchange chromatography (CM-Sepharose) and HPLC (C18 reverse phase). Using an ELISA assay with antibodies directed against enterostatin, two forms of the peptide were identified both in the gut and in the pancreas, with the amino-acid sequences APGPR and VPGPR, respectively. APGPR was found to be the predominant form of enterostatin, whereas only a small amount had the structure VPGPR. Enterostatin in the form of APGPR, when injected intracerebroventricularly in female Sprague-Dawley rats, significantly reduced high-fat food intake in a two-choice situation of low-fat (14% fat by energy) and high-fat (38% fat) food. It is concluded that procolipase is produced in the stomach and secreted into the gastric juice. This is also a novel source of enterostatin.

Background/aims: Treatment of pancreatic steatorrhea with porcine lipase is unsatisfactory because it is rapidly denatured by acidic intraluminal conditions. The aim of this study was to determine if bacterial lipase is resistant to acid denaturation and is active in the presence of bile acids by comparing its stability with that of porcine lipase in gastric and duodenal juice obtained from six patients undergoing a cholecystokinin octapeptide pancreatic function test., Methods: After inactivating native lipolytic activity, both juices were altered to simulate fasting and postprandial conditions in normal patients and patients with pancreatic insufficiency. Gastric juice was adjusted to pH 2, 3, 4, or 6, duodenal juice to pH 4 or 6, and bile acid concentrations to 4 or 12 mmol/L. Nutrients were added to one half of the samples. Initial bacterial or porcine lipolytic concentrations were 25 or 250 U/mL. After a 1-hour incubation at 37 degrees C, lipolytic activity was remeasured., Results: In gastric juice, more bacterial lipolytic activity survived than porcine lipolytic activity at both concentrations in the absence of nutrients and at a concentration of 25 U/mL with nutrients (P < 0.05). In duodenal juice, more bacterial lipolytic activity survived than porcine activity at pH 4 under all test conditions (P < 0.05)., Conclusions: Bacterial lipolytic activity should survive better within the gastrointestinal lumen than porcine lipolytic activity and be more effective to treat steatorrhea.

Development of the muscarinic cholinergic receptor and sensitivity of oxyntic gland mucosa to a muscarinic agonist were studied in rats of various ages. The gastric lumen of the fetal rat at the 20th day of gestation contained a statistically significant amount of basal pepsin, which increased log linearly over the first 30 days of life. Carbachol was effective in stimulating the secretion of pepsin as early as 12 h after birth. Basal acid could be measured in the gastric lumen 12 h after birth. The secretion of basal acid increased log linearly over the first 30 days of life. Carbachol was an effective secretagogue even in the fetal rat. The density of the muscarinic cholinergic receptor of the adult rat oxyntic gland mucosa was 99.3 fmol/mg protein with an apparent equilibrium dissociation constant for quinuclidinyl benzilate of 0.40 nM. The receptor was well developed even in the fetal rat, which bound 79.6 fmol/mg protein with an apparent equilibrium dissociation constant of 0.26 nM. Except for immediately after birth, receptor density was maintained between 70 and 90% of the adult level over the first 30 days of life. These results suggest that cholinergic regulation of gastric acid and pepsin secretion is probably functional by either late gestation or at least immediately after birth.

The phenotypic correlations between pepsinogen, proteases and the debit of acid secretion in patients with the peptic ulcer of duodenum and their parents were studied. It was found that the genetic factors have great influence on the level of pepsinogen and proteases in the basal conditions and under stimulation. In comparison with the general population, we obtained highly reliable increase of the level of pepsinogen and proteases in the groups of patients and their parents.

Fluorescent triacylglycerols containing pyrenedecanoic (P10) and pyrenebutanoic (P4) acids were synthesized and their hydrolysis by lipases from human gastric juice and stomach homogenate was investigated. The existence in stomach homogenate of four different lipolytic enzymes hydrolyzing fluorescent triacylglycerols is suggested by the comparison of various enzymatic properties: acyl chain length specificity, heat inactivation and effect of detergents (Triton X-100 and taurocholate), serum albumin, diethyl-para-nitrophenyl phosphate (E600) and other inhibitors. (1) The acid pH4-lipase hydrolyzes P10-triacylglycerols but not P4-triacylglycerol and exhibited the characteristic properties of the lysosomal lipase: the maximal activating effect of detergents occurs at relatively high concentrations (the substrate/detergent optimal molar ratios were 1:5 and 1:25 for triacylglycerols/taurocholate and triacylglycerols/Triton X-100, respectively); its activity was strongly inhibited by para-chloromercuribenzoate (2.5 mmol/l), but was not significantly affected by serum albumin and E600 (10(-2) mmol/l). (2) The neutral pH7-lipase hydrolyzes P10-triacylglycerols but not P4-triacylglycerol. It is resistant to E600 and heat-stable, similarly to the acid pH4-lipase, but it is well discriminated from the acid enzyme by its substrate/detergent optimal molar ratios (1:2 and 1:3 for triacylglycerols/taurocholate and triacylglycerols/Triton X-100, respectively), whereas higher detergent concentrations, optimal for the acid lipase, are strongly inhibitory for the neutral enzyme. (3) The pH5-lipase present in gastric juice as well as in stomach homogenate exhibited properties obviously discriminating it from the other lipolytic enzymes from stomach homogenate: broad substrate specificity for P10- as well as P4-triacylglycerols, activation by low concentrations of amphiphiles (with optimal ratios triacylglycerols/taurocholate, triacylglycerols/taurocholate and triacylglycerols/phosphatidylcholine around 1:1, 1:3 and 1:0.1, respectively), heat-lability, strong activation by serum albumin and inhibition by E600 (10(-2) mmol/l). This pH5-lipase is the sole lipolytic enzyme present in gastric juice and is probably identical with the well-known 'gastric' lipase. (4) A pH7.5-enzyme is characterized by its specificity for P4-triacylglycerols, its heat-lability at 50 degrees C and its strong inhibition by E600 (10(-2) mmol/l).

Lipase activity was recorded in gastric contents collected from healthy term and preterm neonates. In contrast to pancreatic lipase activity this lipase activity was higher at pH 5.5 than at pH 8.0 and it was more resistent to acid inactivation. Lipase activity was found in gastric contents from all infants who were regularly fed, but was not present in gastric contents from some infants when collected before regular feeding was established. During test meals lipase activity in gastric contents increased considerably in all infants studied. During such a test meal there was a progressive relative decrease in triglycerides whilst diglycerides showed a relative increase suggesting an active lipolytic process in the stomach. An assay procedure for determination of lipase activity in gastric contents is also described.

Chronic experiments on dogs have shown that the damage of extra-secretory pancreatic function by duct ligation caused marked compensatory changes of stomach function. The increase in gastric juice secretion and gastric juice proteolytic activity was accompanied by the reduction in its acidity. In addition to quantitative changes, qualitative shifts were revealed (amylolytic activity in strongly acid pH-reaction), never observed in the gastric juice of intact animals. Partial pancreas resection (up to 75%) both in control and test animals 10-14 months after pancreatic duct ligation was not accompanied by significant changes in gastric juice secretion. Total pancreas resection in dogs with previous pancreatic duct ligation caused neither prompt animal death, as in the control, nor the inhibition of compensatory reactions of gastric juice secretion.