Creating a Framework for Treating Autoimmune Gastritis-The Case for Replacing Lost Acid

Autoimmune gastritis (AIG) is characterized by the destruction of gastric parietal cells, resulting in hypochlorhydria and eventual achlorhydria, as oxyntic glands in the corpus are destroyed and become atrophic. The permanent loss of gastric acid has many impacts-both theoretical and documented. The most concerning of these are hypergastrinemia and increased N-nitroso compounds, both of which increase the risk of gastric cancers. While known deficiencies of B12 and iron are often replaced in AIG, acid is not. Moreover, patients with AIG are often prescribed acid suppression for a stomach that is decidedly no longer acidic, worsening the sequelae of gastric atrophy. Betaine hydrochloride (BHCL) is a short-acting acidifying agent, available over the counter in capsule form. Mealtime acid supplementation has an historic basis and could ameliorate many AIG-related gastrointestinal symptoms. Theoretically, acidification could also reduce the potential for hypergastrinemia and the production of N-nitroso compounds, consequently reducing the risk of gastric cancers. Supplemental vitamin C may also help in preventing gastric N-nitroso formation, regardless of the gastric pH. This narrative review describes the functions of gastric acid in gastrointestinal and immune health, documents the effects of hypochlorhydria in AIG, and proposes potential options for safely re-establishing the acid milieu of the stomach for patients with AIG.

Gastric Microbiota Gender Differences in Subjects with Healthy Stomachs and Autoimmune Atrophic Gastritis

Gender differences and microbiota are gaining increasing attention. This study aimed to assess gender differences in gastric bacterial microbiota between subjects with healthy stomachs and those with autoimmune atrophic gastritis. This was a post hoc analysis of 52 subjects undergoing gastroscopy for dyspepsia (57.7% healthy stomach, 42.3% autoimmune atrophic gastritis). Gastric biopsies were obtained for histopathology and genomic DNA extraction. Gastric microbiota were assessed by sequencing the hypervariable regions of the 16SrRNA gene. The bacterial profile at the phylum level was reported as being in relative abundance expressed as 16SrRNA OTUs (>0.5%) and biodiversity calculated as Shannon-diversity index-H. All data were stratified for the female and male gender. Results showed that women with healthy stomachs had a higher gastric bacterial abundance and less microbial diversity compared to men. Likely due to hypochlorhydria and the non-acid intragastric environment, autoimmune atrophic gastritis seems to reset gender differences in gastric bacterial abundance and reduce biodiversity in males, showing a greater extent of dysbiosis in terms of reduced biodiversity in men. Differences between gender on taxa frequency at the phylum and genus level in healthy subjects and autoimmune atrophic gastritis were observed. The impact of these findings on the gender-specific natural history of autoimmune atrophic gastritis remains to be elucidated; in any case, gender differences should deserve attention in gastric microbiota studies.

Drug Physicochemical Properties and Capsule Fill Determine Extent of Premature Gastric Release from Enteric Capsules

Intrinsically, enteric capsule shells offer several advantages compared to coating of dosage forms with enteric polymers. We undertook a systematic investigation to elucidate capsule-fill parameters that may result in premature gastric drug release from Vcaps^® Enteric capsules (Lonza CHI, Morristown, NJ, USA). Four model drugs with different ionization and solubility profiles were investigated: acetaminophen, ketoprofen, trimethoprim and atenolol. Different fill loads, diluents and drug-to-diluent ratios were explored. Enteric capsules were filled with drug or drug and diluent powder mix and underwent USP II dissolution testing using mini-vessels and paddles. Capsules were tested in pH 2 (0.01 M HCl) or pH 4.5 (3.2 × 10^-5 M HCl) 200 mL acid media to simulate normal, fasted or hypochlorhydric gastric pH, respectively. Acetaminophen, trimethoprim and atenolol displayed premature gastric drug release from enteric capsules. The extent of premature release was dependent on drug solubility, ionization profile and capsule-fill level. At 100 mg drug-fill level, acetaminophen, trimethoprim and atenolol gave rise to 10.6, 12.2 and 83.1% drug release, respectively, in normal, fasted, gastric fluids. Diffusion layer pH of trimethoprim and atenolol in pH 2 media was determined to be pH 6.3 and 10.3, respectively. Upon increasing capsule-fill load using microcrystalline cellulose as a diluent, a significant reduction in premature gastric release was observed. However, including mannitol as a diluent was only effective at decreasing premature drug release at a low drug-to-diluent ratio. Systematic in vitro screening of enteric capsule fills needs to be conducted to ensure that drug product performance is not compromised.

Associations of atrophic gastritis and proton-pump inhibitor drug use with vitamin B-12 status, and the impact of fortified foods, in older adults

BACKGROUND

Atrophic gastritis (AG) and use of proton pump inhibitors (PPIs) result in gastric acid suppression that can impair the absorption of vitamin B-12 from foods. The crystalline vitamin B-12 form, found in fortified foods, does not require gastric acid for its absorption and could thus be beneficial for older adults with hypochlorhydria, but evidence is lacking.

OBJECTIVES

To investigate associations of AG and PPI use with vitamin B-12 status, and the potential protective role of fortified foods, in older adults.

METHODS

Eligible participants (n = 3299) not using vitamin B-12 supplements were drawn from the Trinity-Ulster and Department of Agriculture cohort, a study of noninstitutionalized adults aged ≥60 y and recruited in 2008-2012. Vitamin B-12 status was measured using 4 biomarkers, and vitamin B-12 deficiency was defined as a combined indicator value < -0.5. A pepsinogen I:II ratio <3 was considered indicative of AG.

RESULTS

AG was identified in 15% of participants and associated with significantly lower serum total vitamin B-12 (P < 0.001) and plasma holotranscobalamin (holoTC; P < 0.001), and higher prevalence of vitamin B-12 deficiency (38%), compared with PPI users (21%) and controls (without AG and nonusers of PPIs; 15%; P < 0.001). PPI drugs were used (≥6 mo) by 37% of participants and were associated with lower holoTC concentrations, but only in participants taking higher doses (≥30 mg/d). Regular, compared with nonregular, consumption of fortified foods (i.e., ≥5 and 0-4 portions/wk, respectively) was associated with higher vitamin B-12 biomarkers in all participants, but inadequate to restore normal vitamin B-12 status in those with AG.

CONCLUSIONS

Older adults who have AG and/or use higher doses of PPIs are more likely to have indicators of vitamin B-12 deficiency. Fortified foods, if consumed regularly, were associated with enhanced vitamin B-12 status, but higher levels of added vitamin B-12 than currently provided could be warranted to optimize status in people with AG.

Risk factors associated with gastric malignancy during chronic Helicobacter pylori Infection

Chronic Helicobacter pylori (Hp) infection is considered to be the single most important risk factor for the development of gastric adenocarcinoma in humans, which is a leading cause of cancer-related death worldwide. Nonetheless, Hp infection does not always progress to malignancy, and, gastric adenocarcinoma can occur in the absence of detectable Hp carriage, highlighting the complex and multifactorial nature of gastric cancer. Here we review known contributors to gastric malignancy, including Hp virulence factors, host genetic variation, and multiple environmental variables. In addition, we assess emerging evidence that resident gastric microflora in humans might impact disease progression in Hp-infected individuals. Molecular approaches for microbe identification have revealed differences in the gastric microbiota composition between cancer and non-cancerous patients, as well as infected and uninfected individuals. Although the reasons underlying differences in microbial community structures are not entirely understood, gastric atrophy and hypochlorhydria that accompany chronic Hp infection may be a critical driver of gastric dysbiosis that promote colonization of microbes that contribute to increased risk of malignancy. Defining the importance and role of the gastric microbiota as a potential risk factor for Hp-associated gastric cancer is a vital and exciting area of current research.

The Phylogeny and Biological Function of Gastric Juice-Microbiological Consequences of Removing Gastric Acid

Gastric juice is a unique combination of hydrochloric acid (HCl), lipase, and pepsin. Acidic gastric juice is found in all vertebrates, and its main function is to inactivate microorganisms. The phylogenetic preservation of this energy-consuming and, at times, hazardous function (acid-related diseases) reflects its biological importance. Proton pump inhibitors (PPIs) are one of the most widely used drugs in the world. Due to the reduced prevalence of Helicobacter pylori infection as well as the increased use of inhibitors of gastric acid secretion, the latter has become the most important cause of gastric hypoacidity. In the present manuscript, we review the microbiological consequences of removing gastric acidity. The resulting susceptibility to infections has not been studied extensively, and focus has mainly been restricted to bacterial and parasitic agents only. The strongest evidence concerning the relationship between hypochlorhydria and predisposition to infections relates to bacterial infections affecting the gastrointestinal tract. However, several other clinical settings with increased susceptibility to infections due to inhibited gastric acidity are discussed. We also discuss the impact of hypochlorhydria on the gut microbiome.

HIV related hypochlorhydria does not appear to respond to anti-retroviral therapy in Zambian adults: a case control study

INTRODUCTION

Human Immunodeficiency Virus (HIV) infection is associated with hypochlorhydria but the mechanism is unknown. The objective of this study was to determine effects of anti-retroviral therapy (ART) on gastric physiology as measured by validated markers.

METHODS

We studied HIV infected individuals who were either ART-naïve or on treatment with undetectable viral loads. We measured H.pylori IgG antibodies, pepsinogen (PG) 1 and 2 levels and fasting gastrin-17 using Biohit GastroPanel®. Gastric antral biopsies and juice were obtained for histology and pH respectively. Also included were historical data from HIV negative participants (n = 72) in a previous study, for reference.

RESULTS

We enrolled 84 HIV positive individuals with a median age 42 years (IQR 37-40 years). 55(66%) were female, 32(38%) were ART naïve, and 52(62%) were on ART. Hypochlorhydria (pH>4) was present in 48(57%) of the HIV positive and 18(25%) of the HIV negative individuals (OR 4: 95% CI 1.9-8.5, P<0.001) with no significant effect of ART (OR 0.9: 95% CI 0.3-2.3, P = 0.82). Hypochlorhydria was not associated with the serological detection of corpus atrophy using low PG 1:2 ratio (OR 2.1: 95% CI 0.5-10.2, P = 0.37) or GastroPanel® algorithm, (OR 0.7: 95% CI 0.01-60.1, P = 1.0). ART reduced the frequency of low PG 1:2 ratio (P = 0.001), but not the histological detection in the antrum of atrophy or non-atrophic gastritis.

CONCLUSION

ART use is associated with reduced serological evidence of corpus atrophy but has no effect on fasting pH, supporting earlier data that suggest that the mechanism of HIV-associated hypochlorhydria is multifactorial.

Physiologically Based Absorption Modeling of Salts of Weak Bases Based on Data in Hypochlorhydric and Achlorhydric Biorelevant Media

Physiologically based absorption modeling has been attracting increased attention to study the interactions of weakly basic drug compounds with acid-reducing agents like proton-pump inhibitors and H2 blockers. Recently, standardized gastric and intestinal biorelevant media to simulate the achlorhydric and hypochlorhydric stomach were proposed and solubility and dissolution data for two model compounds were generated. In the current manuscript, for the first time, we report the utility of these recently proposed biorelevant media as input into physiologically based absorption modeling. Where needed, data collected with the biorelevant gastrointestinal transfer (BioGIT) system were used for informing the simulations in regard to the precipitation kinetics. Using two model compounds, a HCl salt and a semi-fumarate co-crystal which as expected dissolve to a greater extent in these media (and in gastric and intestinal human aspirates) compared to what the pH-solubility profile of the free form would suggest, we demonstrate successful description of the plasma concentration profiles and correctly predicted the lack of significant interaction after administration with pantoprazole or famotidine, respectively. Thus, the data reported in this manuscript represent an initial step towards defining biorelevant input for such simulations on interactions with acid-reducing agents.

Amorphous solid dispersions of carvedilol along with pH-modifiers improved pharmacokinetic properties under hypochlorhydoria

Carvedilol (CAR) belongs to biopharmaceutics classification system class-II drugs, with poor aqueous solubility and pH-dependent solubility. The present study aimed to develop a novel amorphous solid dispersion (ASD) of CAR with acidic counter ions for pH modifications in microenvironment to improve the pharmacokinetic properties under hypochlorhydric conditions. CAR-ASD was prepared by freeze-drying in combination with counter ions and hydroxypropyl cellulose, and their physicochemical properties including dissolution behavior, storage stability, and photostability were characterized. Pharmacokinetic studies were carried out after oral administration of CAR samples in both normal and omeprazole-treated (30 mg/kg, p.o.) rats as a hypochlorhydria model. Among the tested six counter ions, citric acid (CA) was found to be a preferable pH-modifier of CAR with respect to the dissolution profile and photostability (both potency and colorimetric evaluation). In CAR-ASD formulation with 50% loading of CA (CAR-ASD/CA50), amorphization of CAR was observed during the preparation process. After the oral administration of crystalline CAR in rats under hypochlorhydric condition, there was a 34.4% reduction in the systemic exposure of CAR compared with that in normal rats. However, orally-dosed CAR-ASD/CA50 resulted in limited alterations of pharmacokinetic behavior between normal and omeprazole-treated rats. From these findings, addition of CA as pH-modifier in CAR-ASD might provide consistent pharmacokinetic behavior of CAR even under hypochlorhydric conditions.

Hypochlorhydria-induced calcium malabsorption does not affect fracture healing but increases post-traumatic bone loss in the intact skeleton

Efficient calcium absorption is essential for skeletal health. Patients with impaired gastric acidification display low bone mass and increased fracture risk because calcium absorption is dependent on gastric pH. We investigated fracture healing and post-traumatic bone turnover in mice deficient in Cckbr, encoding a gastrin receptor that affects acid secretion by parietal cells. Cckbr-/- mice display hypochlorhydria, calcium malabsorption, and osteopenia. Cckbr-/- and wildtype (WT) mice received a femur osteotomy and were fed either a standard or calcium-enriched diet. Healed and intact bones were assessed by biomechanical testing, histomorphometry, micro-computed tomography, and quantitative backscattering. Parathyroid hormone (PTH) serum levels were determined by enzyme-linked immunosorbent assay. Fracture healing was unaffected in Cckbr-/- mice. However, Cckbr-/- mice displayed increased calcium mobilization from the intact skeleton during bone healing, confirmed by significantly elevated PTH levels and osteoclast numbers compared to WT mice. Calcium supplementation significantly reduced secondary hyperparathyroidism and bone resorption in the intact skeleton in both genotypes, but more efficiently in WT mice. Furthermore, calcium administration improved bone healing in WT mice, indicated by significantly increased mechanical properties and bone mineral density of the fracture callus, whereas it had no significant effect in Cckbr-/- mice. Therefore, under conditions of hypochlorhydria-induced calcium malabsorption, calcium, which is essential for callus mineralization, appears to be increasingly mobilized from the intact skeleton in favor of fracture healing. Calcium supplementation during fracture healing prevented systemic calcium mobilization, thereby maintaining bone mass and improving fracture healing in healthy individuals whereas the effect was limited by gastric hypochlorhydria. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1914-1921, 2016.

Endoscopic findings for predicting gastric acid secretion status

BACKGROUND AND AIM

Gastric acidic abnormalities are related to various types of diseases in Helicobacter pylori (H. pylori) infection status. However, no studies have shown correlations between many tiny endoscopic findings and the acid secretion level simultaneously. In the present study, we investigated predictive tiny endoscopic findings of hyperchlorhydria and hypochlorhydria.

METHODS

A total of 223 subjects without organic diseases who underwent esophagogastroduodenoscopy and endoscopic gastrin test (EGT) for estimating gastrin-stimulated gastric acid secretory response between 1999 and 2012 at our institution were retrospectively analyzed. Two blinded expert endoscopists reviewed the images independently and recorded the endoscopic findings.

RESULTS

According to the EGT values, the enrolled subjects were categorized into hyperchlorhydria, normal acid secretion, and hypochlorhydria groups. In all subjects, hematin (odds ratio [95% confidence interval] = 3.32 [1.40-7.84]) and antral erosion(2.88 [1.24-6.70]) were the predictive endoscopic findings for hyperchlorhydria, and swelling of areae gastricae (14.4 [5.74-36.1]) and open-type atrophy (15.1 [7.35-31.1]) were those for hypochlorhydria. In addition, the predictive endoscopic findings for hyperchlorhydria differed according to the H. pylori infection status, hematin in H. pylori-positive subjects and antral erosion in H. pylori-negative subjects, in contrast to those for hypochlorhydria, which were the same irrespective of the H. pylori infection status.

CONCLUSIONS

We could predict the acid secretion status based on the endoscopic findings regardless of H. pylori infection status, which would be of some help for evaluating the risk for acid-related diseases.

The relationship between iron deficiency in patients with Helicobacter pylori-infected nodular gastritis and the serum prohepcidin level

BACKGROUND AND AIMS

Helicobacter pylori (H. pylori) is recognized as a causative agent for unexplained iron-deficiency anemia (IDA). We evaluated many background factors influencing an iron-deficiency state in adult patients with various H. pylori-infected upper gastrointestinal tract diseases.

METHOD

Study 1: H. pylori-infected 121 patients (nodular gastritis (NG) (n = 19), duodenal ulcer (DU) (n = 30), or gastric ulcer (GU) (n = 47), or gastric hyperplastic polyp (GHP) (n = 25)) were enrolled. The RBC count and hemoglobin, iron, ferritin, pepsinogen (PG) I, PG II, gastrin, and anti-H. pylori antibody (Ab) levels in the serum were measured. Study 2: H. pylori-infected 105 patients (NG, n = 19; DU, n = 43; GU, n = 32; GHP, n = 11) and non-H. pylori-infected individuals (n = 35) were examined for the levels of prohepcidin, ferritin, and iron in the serum. In addition, we measured the data before and after the H. pylori eradication.

RESULTS

In the patients with GHP and NG, hypoferritinemia was observed in comparison with the GU and DU patients. In the GHP patients, low levels of PG I, a decreased PG I/II ratio, and hypergastrinemia were observed. The levels of serum prohepcidin in the patients with H. pylori-associated disease were higher than those in the uninfected adults. In the patients with NG, the serum prohepcidin levels were higher than those in the other H. pylori-infected patient groups and decreased after the eradication.

CONCLUSION

H. pylori-related iron-deficiency state might be associated with several factors, such as hypochlorhydria and hepcidin, in patients with GHP or NG.

in rat

The aim of the present study was to search the effective ratio of whole plant of Fumaria vaillantii Loisel (Fumaria vaillantii L.) and fruit of Benincasa hispida Thunb. (Benincasa hispida T.) in composite form, namely “FVBH” for the management of hypochlorhydria along with iron deficiency in male albino rats. Hypochlorhydria refers to suppression of hydrochloric acid secretion by the stomach. Hypochlorhydria was induced by ranitidine in this study. We used four composite extracts of the mentioned plant and fruit with different ratios (1:1, 1:2, 2:1, and 3:2) for searching the most effective composite extract for the correction of hypochlorhydria. Gastric acidity is an important factor for iron absorption. Thus, hypochlorhydria causes iron deficiency in rat and it was prevented significantly by the extract treatment at the ratio of 1:1 of the said plant and fruit. The correction of iron deficiency by the composite extract was compared with iron supplementation to hypochlorhydric rat. It was found that preadministration followed by coadministration of FVBH-1 (1:1) able to prevent the ranitidine-induced hypochlorhydria and iron deficiency. The composite extract, FVBH-1 (1:1) significantly (P<0.05) increased the pepsin concentration, chloride level in gastric juice, iron levels in serum and liver along with blood hemoglobin level than other ratios used here. Hence, it can be concluded that FVBH-1 (1:1) is an effective herbal formulation for the management of hypochlorhydria and related iron deficiency.

Unintended consequences of Helicobacter pylori infection in children in developing countries: iron deficiency, diarrhea, and growth retardation

Helicobacter pylori infection is predominantly acquired early in life. The prevalence of the infection in childhood is low in developed countries, whereas in developing countries most children are infected by 10 y of age. In poor resource settings, where malnutrition, parasitic/enteropathogen and H. pylori infection co-exist in young children, H. pylori might have potentially more diverse clinical outcomes. This paper reviews the impact of childhood H. pylori infection in developing countries that should now be the urgent focus of future research. The extra-gastric manifestations in early H. pylori infection in infants in poor resource settings might be a consequence of the infection associated initial hypochlorhydria. The potential role of H. pylori infection on iron deficiency, growth impairment, diarrheal disease, malabsorption and cognitive function is discussed in this review.

The role of the gastrointestinal microbiome in Helicobacter pylori pathogenesis

The discovery of Helicobacter pylori overturned the conventional dogma that the stomach was a sterile organ and that pH values<4 were capable of sterilizing the stomach. H. pylori are an etiological agent associated with gastritis, hypochlorhydria, duodenal ulcers, and gastric cancer. It is now appreciated that the human stomach supports a bacterial community with possibly 100s of bacterial species that influence stomach homeostasis. Other bacteria colonizing the stomach may also influence H. pylori-associated gastric pathogenesis by creating reactive oxygen and nitrogen species and modulating inflammatory responses. In this review, we summarize the available literature concerning the gastric microbiota in humans, mice, and Mongolian gerbils. We also discuss the gastric perturbations, many involving H. pylori, that facilitate the colonization by bacteria from other compartments of the gastrointestinal tract, and identify risk factors known to affect gastric homeostasis that contribute to changes in the microbiota.

Consensus diagnoses and mode of action for the formation of gastric tumors in rats treated with the chloroacetanilide herbicides alachlor and butachlor

A panel of pathologists (Panel) was formed to evaluate the pathogenesis and human relevance of tumors that developed in the fundic region of rat stomachs in carcinogenicity and mechanistic studies with alachlor and butachlor. The Panel evaluated stomach sections stained with hematoxylin and eosin, neuron-specific enolase, and chromogranin A to determine the presence and relative proportion of enterochromaffin-like (ECL) cells in the tumors and concluded all tumors were derived from ECL cells. Biochemical and pathological data demonstrated the tumor formation involved a nongenotoxic threshold mode of action (MOA) initially characterized by profound atrophy of the glandular fundic mucosa that affected gastric glands, but not surface epithelium. This resulted in a substantial loss of parietal cells and a compensatory mucosal cell proliferation. The loss of parietal cells caused a marked increase in gastric pH (hypochlorhydria), leading to sustained and profound hypergastrinemia. The mucosal atrophy, together with the increased gastrin, stimulated cell growth in one or more ECL cell populations, resulting in neoplasia. ECL cell autocrine and paracrine effects led to dedifferentiation of ECL cell tumors. The Panel concluded the tumors develop via a threshold-dependent nongenotoxic MOA, under conditions not relevant to humans.

on experimental hypochlorhydria in rat

Hypochlorhydria is a common problem in any age of people like other gastric disorders. It has so many etiologies such as sympathetic dominance, antiseretory drug use, excess sugar and refined foods, etc. In the present study, our objective was to search out the effective solvent extract of fruit of Benincasa hispida T. for the management of hypochlorhydria in model male albino rats. Hypochlorhydria was induced in rat as per standard method by oral administration of ranitidine. Different solvent extracts (Hydro-methanol, ethyl acetate, and aqueous) of ripe fruit of B. hispida were prepared following the standard protocol. Various parameters in this concern like free acidity, total acidity, pH, pepsin concentration, chloride and vitamin C levels in gastric juice were measured by standard biochemical and titrimetric methods. It was found that pre-administration followed by co-administration of aqueous extract of B. hispida (ABH) resulted significant correction of ranitidine-induced hypochlorhydria in rat. This aqueous extract-treated group showed increased levels of vitamin C, pepsin, and chloride concentration in gastric juice as well as the antioxidant status significantly (P<0.05) in respect to other extract-treated groups. From the results, it can be concluded that the ABH has most effective anti-hypochlorhydric and antioxidative efficacy than other solvent extracts of said plant fruit.

Effect of Helicobacter pylori infection on symptoms of gastroenteritis due to enteropathogenic Escherichia coli in adults

BACKGROUND

Helicobacter pylori can cause hypochlorhydria in some hosts and predispose to diarrheal infections.

AIMS

We tested the hypothesis that chronic H. pylori infection increases the risk of diarrheal illness due to an acid-sensitive organism: enteropathogenic Escherichia coli (EPEC).

METHODS

After testing healthy adult volunteers for H. pylori, 19 infected and 26 uninfected subjects had gastric pH probes placed and were given 5-10 × 10(9) EPEC organisms; six had previously received a proton pump inhibitor. We measured diarrhea and created a composite gastroenteritis severity score based on symptoms in the 48 h following exposure. Outcomes were compared using logistic regression and analysis of covariance.

RESULTS

More H. pylori-infected (36.8%) than H. pylori-uninfected subjects (7.7%) were hypochlorhydric (P = 0.02). Six (31.6%) H. pylori-infected and five H. pylori-uninfected subjects (19.2%) developed diarrhea (P = 0.34). Hypochlorhydria was a strong risk factor for diarrhea [odds ratio (OR) 6.25, confidence interval (CI): 1.29-30.35]. After adjusting for hypochlorhydria and EPEC dose, H. pylori was not associated with diarrhea (OR 0.89, CI: 0.17-4.58). Among those with symptoms, H. pylori-infected subjects had lower gastroenteritis severity score than did H. pylori-uninfected subjects (2.6, CI: 1.9-3.4 versus 1.5, CI: 1.1-1.9, P = 0.01), particularly if they were also hypochlorhydric (3.8, CI: 2.3-5.3 versus 1.9, CI: 1.3-2.5, P = 0.02).

CONCLUSIONS

In adults, H. pylori infection was associated with hypochlorhydria but had no detectable effect on occurrence of diarrhea. Among symptomatic subjects, H. pylori infection decreased severity of gastroenteritis.

Sonic hedgehog in gastric physiology and neoplastic transformation: friend or foe?

PURPOSE OF REVIEW

To understand the role of sonic hedgehog (Shh) in normal gastric physiology and neoplastic transformation.

RECENT FINDINGS

Emerging evidence shows that gastric epithelial cells produce Shh ligand, which subsequently targets the mesenchyme. This paracrine signaling event is recapitulated by Shh-producing tumors that signal to the supporting stroma to encourage growth. Primary cilia contain components of the hedgehog signaling apparatus, and thus are typically found on responding stromal cells.

SUMMARY

In the stomach, Shh is produced in epithelial cells and received by responding cells in the mesenchyme. In vitro, Shh enhances gastric acid secretion and induces mucin expression. It remains to be determined whether the canonical signaling pathway mediates the observed epithelial effects. Shh expression and signaling is reduced in chronic gastritis, and Shh(-/-) embryos exhibit hyperplasia and metaplastic changes in the gastric mucosa. After its loss in the corpus, Shh is re-expressed in some gastric carcinomas typically arising in the distal stomach or antrum, suggesting that it promotes tumor growth.

Gastric acid secretion and enteric infection in Bangladesh

In developing countries many enteric infections are caused by acid-sensitive pathogens. Failure of the gastric acid barrier to infection has been reported in cholera but gastric acid secretion has been little studied in other enteric infections. We therefore studied basal and stimulated gastric acid in 185 Bangladeshi men admitted to hospital for the treatment of enteric infection. Patients with dysentery (amoebiasis, n = 24 and shigellosis, n = 19) and culture-negative diarrhoea (n = 69) had similar mean gastric acid levels (basal, 3-5 mmol/h; stimulated, 11-17 mmol/h), which remained stable in those patients studied throughout 12 weeks of convalescence. In contrast, patients with secretory diarrhoea caused by cholera or enterotoxigenic Escherichia coli (ETEC) had low gastric acid levels (P < 0.05 compared with other groups) (cholera, n = 34: basal mean 1.8 mmol/h [SD = 2.2], stimulated mean 7.9 mmol/h [SD = 6.4]; ETEC, n = 39: basal mean 2.7 mmol/h [SD = 2.8], stimulated mean 9.4 mmol/h [SD = 7.5]). Cholera patients' gastric acid level rose during convalescence to similar levels to the dysentery patients'. Low gastric acid level was associated with severe disease in patients with cholera (P < 0.02) or ETEC (P < 0.05). Gastric acid level fell with increasing age (P < 0.007) but this did not account for the differences between groups. Gastric acid levels were not associated with Giardia duodenalis or Strongyloides stercoralis co-infection, fever, use of tobacco, or chewing betel nut. Cholera and secretory diarrhoea caused by ETEC may, therefore, partly result from a reduction in gastric acid level which does not occur during dysentery. Factors which impair gastric acid secretion may predispose to diarrhoeal disease in developing countries.