Review article: from gastrin to gastro-oesophageal reflux disease--a century of acid suppression

To commemorate Edkins' discovery of gastrin in 1905, we review a century of progress in the physiology and pathobiology of gastrin and acid secretion especially as it pertains to clinical aspects of gastro-oesophageal reflux disease. Although initially ignored, Edkins' observations eventually led to the enthusiastic investigation of gastrin and acid regulation in peptic ulcer disease, culminating in important therapeutic advances in the management of acid peptic disease. Following the improved understanding of gastric secretory physiology, and the development of acid suppressants with increasing efficacy, the use of surgical intervention for peptic ulcer disease was almost eliminated. Surgery became obsolete with the discovery of Helicobacter pylori. Three other advances are also influencing modern practice: the gastrotoxicity of aspirin and non-steroidal anti-inflammatory drugs is now increasingly appreciated, the role of endoscopy in the diagnosis and therapy of upper gastrointestinal bleeding, and the use of intravenous acid-suppressive agents. The major issue for the future resides within the epidemic of gastro-oesophageal reflux disease. How to diagnose, categorize and treat this condition and how to identify and prevent neoplasia, are the challenges of the new century.

Altered expression of Skp2, c-Myc and p27 proteins but not mRNA after H. pylori eradication in chronic gastritis

Helicobacter pylori infection is associated with increased gastric epithelial cell turnover and non-cardia gastric cancer. Cell cycle progression is dependent on the proteasomal degradation of p27, a cyclin-dependent kinase inhibitor and gastric tumor suppressor, following ubiquitination mediated by Skp2. c-Myc is a transcriptional repressor of p27 and also a target of Skp2. In vitro, H. pylori decreases p27 protein post-translationally. We aimed to determine how p27 is regulated by H. pylori in vivo. The effect of eradicating H. pylori on gastric epithelial p27, Skp2, and c-Myc proteins and mRNA was investigated in 22 patients with chronic gastritis, by immunohistochemistry and laser capture microdissection. The percentage of gastric antral epithelial cells expressing p27 protein was significantly higher after eradication of H. pylori (mean+/-s.e.m. 37+/-2.4% pre-eradication vs 55+/-2.8% post-eradication; P<0.001), while Skp2 and c-Myc protein-expressing cells were lower (Skp2: 35+/-3.8 vs 23+/-2.6%, P=0.009; c-Myc: 47+/-3.6 vs 30+/-3.8%, P<0.001). mRNA expressions of p27, Skp2, and c-Myc (normalized for 18SrRNA) were not changed by H. pylori eradication. H. pylori increases c-Myc and decreases gastric epithelial p27 protein expression in association with increased expression of Skp2, the regulator of p27's ubiquitin ligase complex. H. pylori may influence cell cycle progression and carcinogenesis through post-translational effects on specific gene expression.

p27kip1 deficiency confers susceptibility to gastric carcinogenesis in Helicobacter pylori-infected mice

BACKGROUND & AIMS

Determining how Helicobacter pylori promotes gastric cancer and whether H pylori eradication decreases cancer risk would be helped by suitable murine models. Mice lacking the cyclin-dependent kinase inhibitor p27kip1 are susceptible to carcinogen-induced tumors. Furthermore, p27 stimulates gastric epithelial apoptosis and inhibits proliferation, expression is decreased by H pylori, and low levels are associated with a poor prognosis in gastric cancer. We therefore evaluated p27-deficient mice as a model for H pylori-associated gastric cancer.

METHODS

Wild-type and p27-/- C57BL/6 mice were infected with H pylori mouse-adapted Sydney strain at 6-8 weeks of age and 6-10 mice of each type were euthanized 15, 30, 45, 60, and 75 weeks later.

RESULTS

Uninfected p27-/- mice developed gastric hyperplasia. H pylori-infected p27-/- mice frequently developed intestinal metaplasia (40% at 30 weeks, 67% at 45 weeks), and after 60 weeks 7 of 12 mice developed significant dysplasia and gastric cancer, recapitulating human intestinal-type gastric carcinogenesis. Wild-type mice developed intestinal metaplasia only after 75 weeks of infection; significant gastric dysplasia was observed in 1 animal (P < .05 for each comparison with p27-/- mice). No disease developed in uninfected mice. H pylori infection in p27-/- mice was associated with significantly decreased apoptosis and increased epithelial proliferation, inflammation, and H pylori density compared with infection in wild-type mice.

CONCLUSIONS

p27 loss and H pylori colonization cooperate to produce gastric cancer. The p27-deficient mouse affords opportunities to examine the pathogenesis of H pylori in gastric carcinogenesis and to test eradication and chemopreventive strategies.

Claudin expression in gastric adenocarcinomas: a tissue microarray study with prognostic correlation

The claudins comprise a multigene family of integral membrane proteins, which play a major role in tight junction formation. Aberrations in the expression of certain claudins have been described in a number of malignancies. Our aims were to determine the expression pattern of claudins 1, 3, and 4 as well as ZO-1 in a large series of US patients with gastric cancer and to correlate expression with clinicopathologic and prognostic variables. Tissue microarrays were created from paraffinized samples from 146 patients with distal gastric adenocarcinomas (61 intestinal and 85 diffuse or mixed subtypes). In addition, cores of normal mucosa and intestinal metaplasia were taken from most cases. The microarrays were stained for claudins 1, 3, and 4 and ZO-1, and the intensity of staining was determined using a 3-point scale. Moderate claudin 1 and ZO-1 membranous staining were present, whereas only focal weak claudin 3 and 4 membranous staining was present in normal gastric epithelium. Moderate to strong staining of claudins 1, 3, 4, and ZO-1 was detected in 74%, 48%, 62%, and 74% of the intestinal but in only 46%, 24%, 45%, and 36% of the diffuse subtype of adenocarcinomas (P < .05). Cox multivariate analysis revealed that tumor stage, diffuse subtype, and moderate to strong claudin 4 staining were associated with decreased survival (P < .02). In conclusion, claudins 1, 3, and 4 and ZO-1 are strongly expressed in most gastric intestinal-type adenocarcinomas but less frequently in diffuse gastric cancers. The up-regulation of claudin expression during gastric carcinogenesis suggests their potential utility as diagnostic biomarkers and possible targets for therapeutic intervention.

p27kip1 expression is inversely related to the grade of gastric MALT lymphoma

BACKGROUND

Decreased or lost expression of the cyclin-dependent kinase inhibitor p27kip1 protein has been found to be a poor prognostic factor in many cancers, including gastric cancer.

AIM

To evaluate p27kip1 expression in gastric mucosa-associated lymphoid tissue (MALT) and gastric B-cell lymphoma.

METHODS

Fifty-two cases of gastric lymphoma, mean age 68.7 yr (range 23-90 yr), 11 of chronic Helicobacter pylori-associated gastritis, and 5 of normal gastric mucosa were studied. Patients were classified into two groups. Stage IE gastric lymphomas were defined as local gastric lymphoma of MALT and more advanced stages as advanced gastric lymphoma. Twenty-three patients diagnosed as stage IE, 13 of these were low-grade and 10 diffuse large B-cell lymphoma (DLBL). Twenty-nine patients were at stage IIE or above, 18 with low-grade and 11 with DLBL. Serial sections were evaluated by immunohistochemistry after staining with antibodies against p27/Kip1 and Ki-67.

RESULTS

The proliferative index was higher in gastric DLBL than in low-grade MALT lymphomas, 57.1+/-31.2 vs 17.3+/-20.6 (p=0.0001). The mean p27kip1 expression score for high-grade patients was significantly lower compared with that of low-grade patients, 0.5+/-0.4 and 1.6+/-0.8, respectively (p=0.001). Comparative evaluation of p27kip1 expression in malignant lymphoid cells revealed that B cells of the localized gastric DLBL patients expressed the least p27kip1, 0.36+/-0.32. This value was lower than that of malignant lymphoid cells of patients with advanced DLBL, 0.64+/-0.53, advanced low-grade MALT lymphoma, 1.59+/-0.79, and localized low-grade MALT lymphoma, 1.59+/-0.84. In the multivariate model in which all p27kip1 variables were entered, the expression of p27kip1 in malignant lymphoid cells was inversely correlated with the grade of the lymphoma irrespective of the stage of the disease (p=0.0001), and significantly predicted grade: OR:0.07, 95% CI 0.07-0.31, p=0.0001.

CONCLUSION

p27kip1 may be a putative distinct molecular marker to differentiate between low-grade and high-grade gastric lymphoma.

Mechanisms of Disease: inflammation and the origins of cancer

Many common cancers develop as a consequence of years of chronic inflammation. Increasing evidence indicates that the inflammation may result from persistent mucosal or epithelial cell colonization by microorganisms; including hepatitis B virus and hepatitis C virus, which can cause hepatocellular cancer; human papilloma virus subtypes, which cause cervical cancer, and the bacterium Helicobacter pylori, which can cause gastric cancer. At present, the cause of other chronic inflammatory conditions associated with increased cancer risk, such as ulcerative colitis, is obscure. Particular microbial characteristics as well as the type of the inflammatory response contribute to clinical outcomes via influence on epithelial cell and immune responses. Persistent inflammation leads to increased cellular turnover, especially in the epithelium, and provides selection pressure that result in the emergence of cells that are at high risk for malignant transformation. Cytokines, chemokines, free radicals, and growth factors modulate microbial populations that colonize the host. Thus, therapeutic opportunities exist to target the causative microbe, the consequent inflammatory mediator, or epithelial cell responses. Such measures could be of value to reduce cancer risk in inflammation-associated malignancies.

Low Utility of Endoscopy for Suspected Upper Gastrointestinal Bleeding Occurring in Hospitalized Patients

OBJECTIVES

To determine the clinical utility of upper endoscopy in patients who have upper gastrointestinal bleeding after hospitalization.

METHODS

Patients were studied who underwent upper endoscopy for an indication of suspected upper gastrointestinal bleeding that developed more than 48 hours after hospitalization. Demographic, clinical, and endoscopic data were extracted by chart review. Bleeding was characterized as clinically important (defined as overt bleeding in association with hemodynamic compromise or the need for blood transfusion) or non-clinically important.

RESULTS

Eighty-six patients met inclusion criteria. Clinically important bleeding occurred in 17%. Peptic ulcer disease and gastritis were the most common sources of bleeding in the clinically important and non-clinically important groups, respectively. The bleeding source was not found in 24% of patients. Endoscopic therapy was required in 11% (all of whom had clinically important bleeding). Upper endoscopy prompted no treatment changes in the non-clinically important bleeding group.

CONCLUSIONS

Endoscopic therapy was needed only in the few patients with clinically important bleeding. Nonendoscopic treatment can be recommended for upper gastrointestinal bleeding developing in hospitalized patients who do not meet established criteria for a clinically important bleed.

Spermine oxidation induced by Helicobacter pylori results in apoptosis and DNA damage: implications for gastric carcinogenesis

Oxidative stress is linked to carcinogenesis due to its ability to damage DNA. The human gastric pathogen Helicobacter pylori exerts much of its pathogenicity by inducing apoptosis and DNA damage in host gastric epithelial cells. Polyamines are abundant in epithelial cells, and when oxidized by the inducible spermine oxidase SMO(PAOh1) H(2)O(2) is generated. Here, we report that H. pylori up-regulates mRNA expression, promoter activity, and enzyme activity of SMO(PAOh1) in human gastric epithelial cells, resulting in DNA damage and apoptosis. H. pylori-induced H(2)O(2) generation and apoptosis in these cells was equally attenuated by an inhibitor of SMO(PAOh1), by catalase, and by transient transfection with small interfering RNA targeting SMO(PAOh1). Conversely, SMO(PAOh1) overexpression induced apoptosis to the same levels as caused by H. pylori. Importantly, in H. pylori-infected tissues, there was increased expression of SMO(PAOh1) in both human and mouse gastritis. Laser capture microdissection of human gastric epithelial cells demonstrated expression of SMO(PAOh1) that was significantly attenuated by H. pylori eradication. These results identify a pathway for oxidative stress-induced epithelial cell apoptosis and DNA damage due to SMO(PAOh1) activation by H. pylori that may contribute to the pathogenesis of the infection and development of gastric cancer.

Masking of 13C urea breath test by proton pump inhibitors is dependent on type of medication: comparison between omeprazole, pantoprazole, lansoprazole and esomeprazole

BACKGROUND

The need to withhold acid suppression therapy while awaiting urea breath test results is a common clinical problem in symptomatic patients. It is unclear at present if the dose or type of proton pump inhibitor or the type of test meal govern the apparent masking effect of proton pump inhibitors on the urea breath test.

AIM

To prospectively evaluate Helicobacter pylori detection rates during treatment with four different proton pump inhibitors, utilizing a high-dose citric acid-based 13C urea breath test.

METHODS

Patients positive for Helicobacter pylori by urea breath test were randomized to receive either omeprazole 20 mg/day, pantoprazole 40 mg/day, lansoprazole 30 mg/day or esomeprazole 40 mg/day for 14 days. A repeat breath test was performed on day 14 of treatment.

RESULTS

One hundred and seventy-nine patients, mean age 45.8 +/- 16.8, completed the study. Treatment with omeprazole or pantoprazole prior to urea breath test (UBT) was associated with low false negative results, while lansoprazole and esomeprazole caused clinically unacceptable high false negative rates (pantoprazole 2.2% vs. lansoprazole 16.6%, P = 0.02, vs. esomeprazole 13.6%, P = 0.05; omeprazole 4.1% vs. lansoprazole 16.6%, P = 0.05).

CONCLUSIONS

Proton pump inhibitor-induced false negative results on high-dose citric acid based urea breath test vary with the type of proton pump inhibitor used. Selection of the appropriate test meal and proton pump inhibitor may allow symptomatic individuals to continue their proton pump inhibitors prior to performing a urea breath test.

Positive serology for Helicobacter pylori and vomiting in the pregnancy

INTRODUCTION

Recently, several investigators have suggested that H. pylori may be a contributory factor in hyperemesis gravidarum. The purpose of this study was to evaluate whether seropositivity for IgG antibodies to H. pylori may also be related to nausea, vomiting, heartburn and epigastric pain in pregnancy.

MATERIALS AND METHODS

One hundred and eighty-five women, at term pregnancy, were included in the study. All women completed a questionnaire regarding information on the number of pregnancies and deliveries, weight gain, smoking and gastrointestinal complaints before and during pregnancy. The presence of H. pylori infection was determined by serology.

RESULTS

The overall prevalence rate of H. pylori seropositivity was 45.9%. Women positive for H. pylori IgG were older (28.7+/-4.5 vs. 27.0+/-4.5, p=0.02), had more prior pregnancies (3.2+/-2.1 vs. 2.6+/-1.6, p=0.02) and deliveries (2.6+/-1.6 vs. 2.0+/-1.1, p=0.006) and reported vomiting in the first trimester more frequently than H. pylori negative patients (81.2% vs. 65%, p=0.004). On the other hand vomiting in the second trimester was reported more frequently among smokers during pregnancy compared to non-smokers.

CONCLUSIONS

H. pylori seropositivity is significantly associated with emesis gravidarum but not with gastro-intestinal symptoms later in pregnancy. First trimester vomiting more than doubles the likelihood that the gravida is H. pylori IgG positive.

P27kip1 regulates the apoptotic response of gastric epithelial cells to Helicobacter pylori

BACKGROUND

Helicobacter pylori infection increases the risk of gastric cancer but the molecular mechanisms responsible are not well understood. Gastric cells chronically exposed to H pylori in vitro develop resistance to apoptosis associated with low levels of p27, a cyclin dependent kinase inhibitor and haplo insufficient tumour suppressor gene that is downregulated in gastric cancer.

AIM

To determine whether the low level of p27 protein is responsible for the resistance to apoptosis of gastric cancer cells.

METHODS

The effects of increasing the expression of p27 protein were examined by transiently and stably transfecting a plasmid encoding full length p27 mRNA into apoptosis resistant gastric cancer cell lines with low p27 expression that were derived from AGS gastric cancer cells by chronic H pylori coculture followed by dilutional cloning.

RESULTS

Low p27 expression in the apoptosis resistant derivative cell lines was associated with an approximate 30% decrease in p27 mRNA and an 80% decrease in p27 protein that was not due to increased proteasome dependent degradation of p27 protein. Transient or stable transfection with p27 constructs partially restored the sensitivity of the apoptosis resistant cells to 5-fluorouracil and H pylori induced apoptosis without altering spontaneous apoptotic cell death.

CONCLUSIONS

These results demonstrate that p27 positively regulates, at least in part, the apoptotic response of gastric epithelial cells to H pylori. Low gastric p27 may promote gastric carcinogenesis associated with H pylori infection by inhibiting apoptotic pathways.

Gastroesophageal reflux disease: then and now

Although Galen first described esophagitis almost 2000 years ago, its relation to acid was only recognized in the 19th century by Rokitansky. Considerably more interest in the symptoms and complications of esophagitis has been evident over the last century, as gastroesophageal reflux disease displaced peptic ulceration and became the principal acid-related disease of our times. Of particular interest has been the recognition of the clinical significance of the previously overlooked extraesophageal manifestations of the disease such as laryngitis, asthma, and sleep disturbance. The evolution of highly effective medical therapy has over the last decade drastically reduced the need for surgical intervention for control of symptoms except under select conditions, especially volume-related reflux and children with refractory symptoms. The proton pump inhibitor class of drugs is indisputably the most effective overall form of management, while individual proton pump inhibitors appear to be equivalent in their efficacy. Issues that remain to be resolved include the management of nonerosive gastroesophageal reflux disease, the long-term dependence of many patients on acid-suppressing medication, and the recognition of atypical manifestations and rare but serious complications of gastroesophageal reflux disease. In this respect, Barrett's esophagus still presents a major biologic and management conundrum for the physicians and scientists alike.

Helicobacter pylori

PURPOSE OF REVIEW

Helicobacter pylori is an important human pathogen, responsible for most peptic ulcer disease, gastritis and gastric malignancies. H. pylori has several unique features: it is highly adapted for gastric colonization, yet it produces clinical consequences in a small minority, its genome is known, and it is the only bacterium strongly associated with cancer. H. pylori is therefore of great interest to clinicians and researchers of many, often disparate, disciplines. We highlight recent advances in this fast changing field from many different areas.

RECENT FINDINGS

The major contentious clinical issues relate to the synergistic gastrotoxic interactions of H. pylori with non-steroidal anti-inflammatory drugs, and a possible association of H. pylori with atherosclerotic events. Accumulating evidence implicates genetic variation in the inflammatory response to H. pylori in the etiology of the increased risk of gastric cancer after H. pylori infection. Studies of pathogenesis have been aided by increasingly sophisticated murine models. The effects in gastric epithelial cells of two of the major virulence factors (genes within the cag pathogenicity island and the vacuolating cytotoxin, VacA) of H. pylori illustrate the complex network of cellular reactions activated by H. pylori. The metabolism of H. pylori is dependent on the availability of hydrogen.

SUMMARY

Basic science research into H. pylori continues to elucidate the mechanisms by which H. pylori infection causes disease. These findings have implications for the design of novel therapies and for improving clinical strategies to identify at-risk individuals. Many are also worthy of consideration for other epithelial-microbial interactions.

GERD 2003 -- a consensus on the way ahead

Gastroesophageal reflux disease (GERD) has in recent times become an important public health issue owing to the considerable health care resources utilized in its management, its deleterious effect on quality of life and the increasing prevalence of a relatively rare complication of reflux disease - esophageal adenocarcinoma. We review here the major current challenges in the field of reflux disease and its complications, and provide some approaches that may be useful in management. The issues to be faced include the very limited comprehension of the reasons behind the increasing prevalence of the disease, difficulties in correlating symptoms with objective data of pathological gastroesophageal reflux and the relatively unsophisticated tools we are employing to investigate the underlying pathophysiology. It is certain that the lack of well-defined and characterized methodologies to compare the effects of therapy require the development of more effective questionnaire-type analytic tools. In regard to treatment, there is little doubt that the widely prescribed proton pump inhibitors have dose-equivalent efficacy and are the most highly effective agents capable of suppressing acid, controlling many of the symptoms of GERD and healing erosions. Nevertheless, many patients continue to experience symptoms on withdrawal or at night. Pharmacological agents that can effectively increase lower esophageal sphincter pressure or promote motility are as yet unavailable. Although the introduction of laparoscopic techniques has resulted in a modest revival in surgical intervention using a variety of 'wrap-type' operations, the indications are few and the procedure is associated with a significant morbidity and even mortality especially if the expertise of the surgeon is an issue. Endoscopic techniques of regulating reflux are at this time experimental and not applicable to the general population. Intestinal metaplasia in the lower esophagus is probably very common. Whether and how to, first, screen for, and then, perform surveillance in Barrett's esophagus remains highly problematic and contentious.

Helicobacter pylori increases proteasome-mediated degradation of p27(kip1) in gastric epithelial cells

Helicobacter pylori infection is associated with increased gastric epithelial cell turnover and is a risk factor for noncardia gastric cancer. H. pylori reduces the expression of p27 protein, a cyclin-dependent kinase inhibitor of the G(1) to S-phase cell cycle transition and gastric tumor suppressor gene. Although cell cycle dysregulation associated with decreased p27 may contribute to gastric carcinogenesis, how H. pylori reduces p27 in gastric epithelial cells remains unknown. In the present study, we investigated the mechanisms of the p27 decrease, using AGS and MKN28 gastric epithelial cells cocultured with H. pylori strains under conditions of defined cell cycle distribution. The expression of p27 protein was reduced by H. pylori in a dose- and time-dependent manner. Northern blot and pulse-chase analyses revealed that this reduction was not regulated at a transcriptional level but by accelerated p27 degradation via a proteasome-dependent pathway. Despite up-regulation of the proteasome-dependent degradation of p27 protein, neither threonine 187-phosphorylated p27 nor skp2 (the ubiquitin ligase for p27) were increased. Furthermore, H. pylori impaired p27 ubiquitination and did not increase global proteasomal function. These results indicate that H. pylori increases the degradation of p27 through a proteasomal pathway distinct from the physiological pathway that degrades p27 during cell cycle progression. Putative virulence genes of H. pylori (cagA, cagE, or vacA) played no role in reducing p27 expression. Increased degradation of p27 by H. pylori through a proteasome-dependent, ubiquitin-independent pathway may contribute to the increased risk of gastric cancer associated with chronic H. pylori infection.

p16Ink4a is overexpressed in H. pylori-associated gastritis and is correlated with increased epithelial apoptosis

BACKGROUND

Cell cycle regulatory proteins may be critical targets during carcinogenesis. We have previously shown that chronic H. pylori infection is associated with decreased expression of the cyclin dependent kinase inhibitor (CDI) p27kip1. Loss of p27kip1 and p16Ink4a (p16) expression, another CDI, has been reported during the progression of gastric tubular adenomas to advanced gastric cancer. The aim of the current study was to examine whether H. pylori infection also affects the expression of p16 in the gastric mucosa of H. pylori-infected patients.

METHODS

p16 expression was evaluated in gastric antral biopsies by immunohistochemistry in 50 patients with nonulcer dyspepsia (n = 18 uninfected, n = 32 H. pylori infected, 24 by cagA+ strains). Adjacent sections were stained for proliferating epithelial cells (by Ki67) and for apoptotic cells (by TUNEL assay).

RESULTS

Both in H. pylori infected and uninfected patients the expression of p16 was higher in the neck and base of the gland than in the foveolar region. Epithelial staining for p16 was increased with H. pylori infection (31.3% vs. 11.1% in the foveolar region, 68.8% vs. 27.8% in the neck and 75% vs. 50% in the glandular base). There was no correlation between the expression of 16 and proliferation but there was a significant positive correlation between apoptosis and 16 immunostaining.

CONCLUSIONS

The tumor suppressor gene 16 is over expressed in gastric epithelial cells of H. pylori infected patients and this is associated with an increase in apoptosis. These findings suggest a possible role for this cell cycle regulator in the increase in gastric cell turnover that is associated with H. pylori infection.

Effect of proton pump inhibitors on the continuous real time (13)C-urea breath test

OBJECTIVE

The aim of this study was to evaluate the accuracy of a new, continuous real time (13)C-urea breath test, BreathID, for the diagnosis of Helicobacter pylori in patients taking proton pump inhibitors (PPIs).

METHODS

Fifty-two consecutive patients, positive for H. pylori by BreathID, were prospectively evaluated. Patients were randomized to receive either omeprazole 20 mg/day or pantoprazole 40 mg/day for 14 days. A repeat breath test was performed on day 14 while patients received their last PPI pill. Patients were given a test drink containing 75 mg (13)C-urea and 4.0 g citric acid. Real time, continuously sampled expired (13)CO(2), obtained within 6-20 min, was compared with measurement of expired (13)CO(2) by isotope ratio mass spectrometry (IRMS).

RESULTS

A full set of test data was available for 43 patients. After 14 days of treatment with PPIs, false negative detection of H. pylori occurred in only 1/43 (2.3%) patients examined by continuous real time (13)C-urea breath test compared with 2/43 (4.6%) patients examined by IRMS. With the exception of one case, complete agreement was observed between BreathID and the IRMS breath tests at both baseline and after PPI treatment. PPI treatment was associated with three different types of responses on UBT: 1) one third of the patients developed a significant decrease in the (13)CO(2)/(12)CO(2) excretion, 2) roughly one third developed a significant increase in the post-PPI breath test results, and 3) results did not change significantly in the remaining patients. Linear regression analysis of 43 H. pylori-positive subjects indicated a significant positive association between baseline and post-PPI Delta (13)CO(2)/(12)CO(2) excretion.

CONCLUSIONS

The use of a single test drink containing 4.0 g citric acid in BreathID, resulted in a low number of false negative results associated with sustained PPI treatment. Although there were some differences between BreathID versus IRMS, the type of PPI and the sampling method used do not appear to play a critical role in the detection of H. pylori by BreathID. According to these results, BreathID is a reliable tool for testing H. pylori in patients taking PPIs.

Comparison of calcium supplementation or low-fat dairy foods on epithelial cell proliferation and differentiation

Epidemiological evidence suggests that dietary calcium and vitamin D intake are inversely related to incidence of colon cancer. Previous studies have demonstrated that supplementation of the diet with calcium in the form of calcium tablets or low-fat dairy foods alters colonic epithelial cell proliferation from a higher- to a lower-risk pattern. The present study compared relative effects of administration of calcium carbonate at approximately 900 mg/day (calcium) with those of a low-fat dairy food diet providing about the same amount of calcium (dairy) in a cross-over "head-to-head" study of 40 subjects at risk for colonic neoplasia. Dietary intake of macronutrients was similar in the two study periods, except for a slight increase in protein intake during dairy calcium supplementation. Rectal epithelial cell proliferation was studied in flat endoscopically normal-appearing mucosa at baseline and at the end of each of the two study periods and showed a significant reduction in epithelial crypt cell labeling index from 12.5% to 9.1% (calcium) or 9.3% (dairy) as well as in proliferating cells in the upper 40% of the crypt from 0.09 to 0.03 in the calcium- and low-fat dairy-supplemented intervention groups. No significant changes in two epithelial cell differentiation markers, cytokeratin AE1 and acidic mucins, were found. Furthermore, there were no differences in epithelial cell apoptosis or expression of the proapoptotic gene product BAK. These data indicate that increased dietary calcium given as supplements or in the diet in low-fat dairy foods lowers epithelial cell proliferation indexes from a higher- to a lower-risk pattern. Because supplemental calcium has been shown to reduce the recurrence of colonic adenomatous polyps in patients at increased risk for colonic neoplasia, our data suggest that supplemental low-fat dairy foods may also be effective.