Critical review of acid suppression in nonvariceal, acute, uppergastrointestinal bleeding

Nonvariceal, upper gastrointestinal (GI) bleeding is a very common source of morbidity and mortality. The concept of ulcer clot dissolution being facilitated by a low gastric pH has allowed us to better understand the pathophysiology of nonvariceal upper GI bleeding. Placebo-controlled trials have shown the benefit of oral proton pump inhibitor administration in contrast to H(2) receptor antagonists. Furthermore, our recent experience with intravenous proton pump inhibitors has reinforced these observations.

The dyspepsia alphabet: DU, GU, GERD, NERD, NUD/FD and UD

The care of patients with dyspepsia may be almost as confusing as the many terms that are used to describe this very common symptom. A symptom-based approach may prove to be ideal for the patient with undiagnosed dyspepsia. This brief overview describes some of the many terms used to describe dyspepsia. Clearly, new treatment algorithms are needed for the care of patients with undiagnosed dyspepsia seen in a primary care setting.

Are the orally administered proton pump inhibitors equivalent? A comparison of lansoprazole, omeprazole, pantoprazole, and rabeprazole

Four proton pump inhibitors (PPIs) are currently marketed in various parts of the world, and all of these (lansoprazole, omeprazole, pantoprazole, and rabeprazole) are available for prescription use in the United States. As a therapeutic group, the PPIs are highly useful for the relief of symptoms and healing of gastroesophageal reflux disease, gastric and duodenal ulcer disease, eradication of Helicobacter pylori infection, prevention and treatment of nonsteroidal anti-inflammatory drug (NSAID)-associated damage, management of hypersecretory states such as Zollinger-Ellison syndrome, and care of patients with non-variceal upper gastrointestinal bleeding, or non-ulcer dyspepsia. The pathophysiologic basis of these management benefits lies in the potent gastric acid inhibitory effects of the PPIs. There are differences between the PPIs in their pharmacokinetics, pharmacodynamics, influence by food and antacids, clinical efficacy, and potential for drug interactions. It is not always clear whether these often subtle variations are necessarily of clinical importance. The physician's choice of one PPI over another must rest with her/his interpretation of the clinical importance of the generally small differences between PPIs, their approval for treatment of specific clinical indications within the physician's practice jurisdiction, and the strength of the evidence based on the quantity and quality of the supporting clinical trials.

Implications of antibiotic resistance in the management of Helicobacter pylori infection: Canadian Helicobacter Study Group

Eradication of Helicobacter pylori from the gastric and duodenal mucosa is an important clinical goal in the treatment of infected patients with peptic ulcer disease and other H pylori-associated conditions. Although several oral drug combination regimens are associated with eradication rates of approximately 85% in controlled trials, the success rate in patients infected with a resistant strain of H pylori is closer to 75%. Resistance to metronidazole and clarithromycin, which are common components of combination treatment regimens, is of greatest concern. Reported rates of H pylori resistance to various antibiotics vary considerably. In Canada, the data documenting H pylori susceptibility are limited but suggest that resistance to these antibiotics varies geographically and within specific treatment groups. Although susceptibility testing is not a prerequisite for initial treatment of individual patients infected with H pylori, formal efforts to identify and monitor both the causes and prevalence of antibiotic resistance across Canada are a much needed step in the ongoing management of this important infection. Recommended treatment regimens may be useful, even for treating apparently resistant H pylori strains. However, it is important to understand the mechanisms of the development of resistant strains to manage patients with treatment failure better.

Small bowel review: part I

In the past year, there have been many advances in the area of small bowel physiology and pathology. More than 1500 papers were assessed in preparation for this review. Some were selected and reviewed, with a particular focus on presenting clinically useful information for the practising gastroenterologist. Relevant review articles have been highlighted, and important clinical learning points have been stressed. The topics are varied in scope, and wherever possible show a logical progression from basic physiology to pathophysiology to clinical disorders and management.

Endoscopic comparison of esophageal and gastroduodenal effects of risedronate and alendronate in postmenopausal women

BACKGROUND & AIMS

Bisphosphonates are effective treatment for osteoporosis, but upper gastrointestinal injury associated with some compounds has caused concern. This study compared the incidence of gastric ulcers after treatment with risedronate, a pyridinyl bisphosphonate, and alendronate, a primary amino bisphosphonate. Esophageal and gastroduodenal injury assessed by endoscopy scores was a secondary endpoint.

METHODS

Healthy, postmenopausal women (n = 515) received 5 mg risedronate (n = 255) or 10 mg alendronate (n = 260) for 2 weeks. At baseline and on days 8 and 15, subjects underwent endoscopy and evaluator-blinded assessment of the esophageal, gastric, and duodenal mucosa.

RESULTS

Gastric ulcers were observed during the treatment period in 9 of 221 (4.1%) evaluable subjects in the risedronate group compared with 30 of 227 (13.2%) in the alendronate group (P < 0.001). Mean gastric endoscopy scores for the risedronate group were lower than those for the alendronate group at days 8 and 15 (P </= 0.001). Mean esophageal and duodenal endoscopy scores were similar in the 2 groups at days 8 and 15. Esophageal ulcers were noted in 3 evaluable subjects in the alendronate group, compared with none in the risedronate group, and duodenal ulcers were noted in 1 evaluable subject in the alendronate group and 2 in the risedronate group.

CONCLUSIONS

At doses used for the treatment of osteoporosis, risedronate was associated with a significantly lower incidence of gastric ulcers than alendronate. These findings confirm that bisphosphonates differ in their potential to damage the gastroesophageal mucosa.

Quality of life rapidly improves with budesonide therapy for active Crohn's disease. Canadian Inflammatory Bowel Disease Study Group

Our aims were to assess the impact on health-related quality of life (HRQOL) of a controlled ileal release (CIR) formulation of budesonide in active Crohn's disease (CD) and further define the role of HRQOL, using the Inflammatory Bowel Disease Questionnaire (IBDQ), in assessing outcome in CD. A randomized trial was conducted in 258 patients with active ileal or ileocecal CD. Budesonide CIR 1.5 mg, 4.5 mg, 7.5 mg, or placebo was given b.i.d. for 8 weeks. IBDQ score changes were compared among groups. Correlations for IBDQ and Crohn's Disease Activity Index (CDAI) scores were calculated. Mean IBDQ scores improved significantly over placebo by 2 weeks in budesonide 15 mg (155+/-38; p = 0.006) and 9 mg groups (157+/-33; p = 0.0002). Bowel, systemic, social, and emotional subscores were also significantly better (p < 0.002) at 2 and 8 weeks in the 9 mg group. Improved HRQOL scores correlated well with decreased CDAI (-0.8 < r < -0.4). Average per item change in IBDQ at remission was 1.17 to 1.48. Prior surgery (p < 0.005) or current smoker (p < 0.05) status predicted poorer initial HRQOL but not response. Budesonide CIR 9 or 15 mg/day rapidly and significantly improved HRQOL in active CD.

Variability of the intestinal uptake of lipids is genetically determined in mice

The response of the plasma cholesterol concentration to changes in dietary lipids varies widely in humans and animals. There are variations in the in vivo absorption of cholesterol between different strains of mice. This study was undertaken in three strains of inbred mice to test the hypotheses that: (i) there are strain differences in the in vitro uptake of fatty acids and cholesterol and (ii) the adaptability of the intestine to respond to variations in dietary lipids is genetically determined. An in vitro intestinal ring technique was used to assess the uptake of medium- and long-chain fatty acids and cholesterol into jejunum and ileum of adult DBA/2, C57BL6, and C57L/J mice. The jejunal uptake of cholesterol was similar in C57L/J, DBA/2, or C57BL6 fed ad libitum a low-fat (5.7% fat, no cholesterol) chow diet. This is in contrast to a previous demonstration that in vivo cholesterol absorption was lower in C57L/J than in the other murine strains. The jejunal uptake of several long-chain fatty acids was greater in DBA/2 fed for 4 wk the high-fat (15.8% fat and 1.25% cholesterol) as compared with the low-fat diet. Furthermore, on the high-fat diet, the uptake of many long-chain fatty acids was higher in DBA/2 than in C57BL6 or C57L/J. The differences in cholesterol and fatty acid uptake were not explained by variations in food uptake, body weight gain, or the weight of the intestine. In summary: (i) there are strain differences in the in vitro intestinal uptake of fatty acids but not of cholesterol; (ii) a high-fat diet enhances the uptake of long-chain fatty acids in only one of the three strains examined in this study; and (iii) the pattern of strain- and diet-associated alterations in the in vivo absorption of cholesterol differs from the pattern of changes observed in vitro. We speculate that genetic differences in cholesterol and fatty acid uptake are explained by variations in the expression of protein-mediated components of lipid uptake.

Applications of recombinant DNA technology in gastrointestinal medicine and hepatology: basic paradigms of molecular cell biology. Part C: protein synthesis and post-translational processing in eukaryotic cells

The translation of mRNA constitutes the first step in the synthesis of a functional protein. The polypeptide chain is subsequently folded into the appropriate three-dimensional configuration and undergoes a variety of processing steps before being converted into its active form. These processing steps are intimately related to the cellular events that occur in the endoplasmic reticulum and Golgi compartments, and determine the sorting and transport of different proteins to their appropriate destinations within the cell. While the regulation of gene expression occurs primarily at the level of transcription, the expression of many genes can also be controlled at the level of translation. Most proteins can be regulated in response to extracellular signals. In addition, intracellular protein levels can be controlled by differential rates of protein degradation. Thus, the regulation of both the amounts and activities of intracellular proteins ultimately determines all aspects of cell behaviour.

Ontogeny of intestinal nutrient transport

Children born prematurely lack the ability to digest and to absorb nutrients at rates compatible with their nutritional needs. As a result, total parenteral nutrition may need to be given. While this nutritional support may be lifesaving, the baby who receives this therapy is exposed to the risks of possible sepsis, catheter dysfunction, and liver disease. The rodent model of postnatal development provides a useful framework to investigate some of the cellular features of human intestinal development. The up-regulation of intestinal gene expression and precocious development of intestinal nutrient absorption can be achieved by providing growth factor(s) or by modifying the composition of the maternal diet during pregnancy and nursing or the weaning diet of the infant. Accelerating the digestive and absorptive functions of the intestine would thereby allow for the maintenance of infant nutrition through oral food intake, and might possibly eliminate the need for, and risks of, total parenteral nutrition. Accordingly, this review was undertaken to focus on the adaptive processes available to the intestine, to identify what might be the signals for and mechanisms of the modified nutrient absorption, and to speculate on approaches that need to be studied as means to possibly accelerate the adaptive processes in ways which would be beneficial to the newborn young.

Defining the role of fiberoptic sigmoidoscopy in the investigation of patients presenting with bright red rectal bleeding

OBJECTIVE

This study was done to determine whether sigmoidoscopy could theoretically constitute sufficient investigation for some patients with bright red rectal bleeding.

METHODS

One hundred and forty-three patients undergoing investigative colonoscopy for bright red rectal bleeding and whose source of bleeding was identified were studied. The investigation took place in a large urban hospital over an 11-month period. Data obtained included changes in stool pattern, characteristics of the bleeding, lesions identified, and the distance of the lesion from the anus.

RESULTS

In patients younger than 55 yr, all serious lesions except for one malignancy in a patient with massive bleeding lay within 60 cm of the anus and theoretically within reach of the fiberoptic sigmoidoscope. The mixing of red blood with stool was commonly due to distal lesions, especially hemorrhoids.

CONCLUSIONS

In young persons with bright red rectal bleeding, fiberoptic sigmoidoscopy may prove to constitute appropriate initial investigation.

Applications of recombinant DNA technology in gastrointestinal medicine and hepatology: basic paradigms of molecular cell biology. Part B: eukaryotic gene transcription and post-transcriptional RNA processing

The transcription of DNA into RNA is the primary level at which gene expression is controlled in eukaryotic cells. Eukaryotic gene transcription involves several different RNA polymerases that interact with a host of transcription factors to initiate transcription. Genes that encode proteins are transcribed into messenger RNA (mRNA) by RNA polymerase II. Ribosomal RNAs (rRNAs) and transfer RNAs (tRNAs) are transcribed by RNA polymerase I and III, respectively. The production of each mRNA in human cells involves complex interactions of proteins (ie, trans-acting factors) with specific sequences on the DNA (ie, cis-acting elements). Cis-acting elements are short base sequences adjacent to or within a particular gene. While the regulation of transcription is a pivotal step in the control of gene expression, a variety of molecular events, collectively known as 'RNA processing' add an additional level of control of gene expression in eukaryotic cells. (Pour le résumé, voir page suivante)

From bench to bedside to bug: an update of clinically relevant advances in the care of persons with Helicobacter pylori- associated diseases

In-depth meetings of the XIth International Workshop on Gastroduodenal Pathology and Helicobacter pylori led to the presentation and discussion of extensive new data on H. pylori and its diseases. The mode of transmission of H. pylori remains unclear, and it remains unknown why only a small proportion of infected individuals develop duodenal or gastric ulcer disease and even fewer develop gastric cancer. The role of H. pylori eradication in persons with uninvestigated dyspepsia remains controversial. New clinical trials of H. pylori treatment show symptom relief and improvement in the quality of life of persons with functional dyspepsia, especially in those with ulcer-like or reflux-like dyspepsia. Clearly the move is toward symptom-based management of persons with dyspepsia, with fewer endoscopies being needed in the otherwise healthy young dyspeptic patients. It remains controversial whether eradicating H. pylori in duodenal ulcer or functional dyspepsia increases the risk of subsequent development of gastroesophageal reflux disease. The one-week proton pump inhibitor-based triple regimens remain the gold standard of H. pylori therapy, but some of the ranitidine bismuth citrate plus two antibiotic regimens also achieve an 80% H. pylori eradication rate on an intention-to-treat basis. While the urea breath test remains the noninvasive test of choice, interesting new data are available on the use of stool antigen testing to diagnose H. pylori infection. The number of H pylori-associated gastroduodenal diseases grows to include possible liver, vascular, immune and skin conditions.

Applications of recombinant DNA technology in gastrointestinal medicine and hepatology: basic paradigms of molecular cell biology. Part A: eukaryotic gene structure and DNA replication

Progress in the basic sciences of cell and molecular biology has provided an exciting dimension that has translated into clinically relevant information in every medical subspecialty. Importantly, the application of recombinant DNA technology has played a major role in unravelling the intricacies related to the molecular pathophysiology of disease. This series of review articles constitutes a framework for the integration of the database of new information into the core knowledge base of concepts related to the pathogenesis of gastrointestinal disorders and liver disease. The goal of this series of three articles is to review the basic principles of eukaryotic gene expression. The first article examines the role of DNA in directing the flow of genetic information in eukaryotic cells.

Gastric cancer and other endoscopic diagnoses in patients with benign dyspepsia

BACKGROUND

It has been suggested that endoscopy could be replaced with non-invasive assessment of helicobacter status in the initial work up of young dyspeptic patients without sinister symptoms.

AIMS

To determine the incidence of gastro-oesophageal malignancy in young dyspeptic patients.

METHODS

The Alberta Endoscopy Project captured clinical and demographic data on all endoscopies performed from April 1993 to February 1996 at four major adult hospitals in Alberta. The endoscopic and histological diagnosis in a subgroup of patients under 45 years of age without alarm symptoms that had undergone gastroscopy was reviewed. In addition, a random list of 200 patients was generated and their medical records reviewed in order to assess the proportion with symptoms suitable for a non-invasive management strategy.

RESULTS

Gastroscopy was performed in 7004 patients under 45 years. In 3634 patients (56% female) alarm type symptoms were absent; 78.9% of patients had symptoms amenable to a non-invasive initial approach, giving a corrected sample size of 2867 patients (correction factor 0.789). Three gastric cancers, one case of moderate dysplasia, 10 biopsy proved cases of Barrett's oesophagus, and 19 oesophageal strictures/rings were detected within this sample. The corrected prevalence of gastric cancer in this select population was 1.05 per thousand patients.

DISCUSSION

Endoscopy yielded three gastric cancers in this sample of under 45 year old dyspeptic patients without sinister symptoms. While initial non-invasive screening with one-week triple therapy for helicobacter positive individuals is unlikely to have a detrimental outcome the physician is advised to consider endoscopy in patients with persisting, recurrent, or sinister symptoms.

Therapy for H. pylori infection

The discovery that peptic ulcers can be caused by gastroduodenal infection with Helicobacter pylori and cured by eradication of this bacterial presence has made a profound impact on ulcer management. This article reviews the principles behind such treatment and the regimens in current use, including proton pump inhibitor triple therapies and ranitidine bismuth citrate triple therapies.

Comparison of 200 mg cimetidine with multiple doses of antacid on extent and duration of rise in gastric pH in volunteers

The effects on gastric pH of a single administration of 200 mg cimetidine (Tagamet HB) were compared to multiple doses of a liquid antacid (Mylanta) using a pH microelectrode. Gastric pH was monitored for 8 hr in 20 normal fasting volunteers in a crossover design to compare Tagamet HB (two 100-mg tablets administered as a single dose) with Mylanta Suspension, an initial 17.5-ml dose of antacid with additional doses given when gastric pH fell below 3.5. Both treatments increased the pH above 3.5 during the first hour following treatment, with Mylanta being more effective than Tagamet HB. Interestingly, to sustain the reduction in acidity during this 1-hr interval, a mean of 2.45 doses of antacid were administered. Although multiple doses of Mylanta kept the pH above 3.5 (for at least 25% of the time) for the first 4 hr, the single administration of 200 mg of Tagamet HB maintained gastric pH above 3.5 (greater than 25% of time) for the full 8 hr of the study. Compared to Mylanta, the percent of time gastric pH was >3.5 was significantly higher with Tagamet HB during the 3rd to 8th hour after dosing. This study demonstrates that 200 mg of cimetidine administered as Tagamet HB is significantly more effective and has a much longer duration of action in raising gastric pH >3.5 than six doses of Mylanta.

Food but not a chemically defined diet interferes with maintenance of intragastric pH at a predefined level using continuous pH-stat-adjusted intravenous infusion of ranitidine in healthy volunteers

Eight healthy volunteers were used to determine the influence of a normal diet (food) versus an isocaloric chemically defined diet (CDD) on the dose of ranitidine infused continuously over 12 hr, required to maintain the intragastric pH > or = 5 or above. The dose of ranitidine used was adjusted by the pH-stat instrument, Gastrojet, and a target pH of 5.0 was selected. The average ranitidine dose was 43.5 mg for food, 28.3 mg for CDD, and 25.7 mg for fasting. Despite the higher dose of ranitidine used with food, the control of pH was lower than the desired and preset value of pH > or = 5: the average mean pH was 3.99 for food, 5.11 for CDD, and 5.75 for fasting. The percentage of time of pH > or = 5 was 32.0% for food, 73.7% for CDD, and 80.1% for fasting. Thus, when persons are fed a normal diet there is a need for higher doses of ranitidine to maintain the gastric pH > or = 5.0. Even with frequent monitoring of intragastric pH with the Gastrojet, there is much greater variability in pH control with food than with CDD or fasting, and the preset and desired pH level was not achieved. This difficulty in achieving desired end points of pH control when switching from a fasting to a fed state needs to be considered when intravenous ranitidine is used to obtain strict control of intragastric pH.

Canadian Helicobacter Study Group Consensus Conference on the Approach to Helicobacter pylori Infection in Children and Adolescents

Gastric infection with Helicobacter pylori is common in both children and adults, but children are considerably less susceptible to peptic ulcers and other pathological sequelae. As a result, the risk to benefit ratio of diagnostic studies and therapeutic regimens for H pylori in adults are likely different from those in pediatric populations. These guidelines for the management of pediatric H pylori infection, developed by the Canadian Helicobacter Study Group, are designed to identify when the diagnosis and treatment of H pylori may improve patient care. Given the low prevalence of this infection in Canada, it is important to recognize that indiscriminate testing and treatment programs in children are not recommended, and indeed may threaten the optimal care of children. Diagnostic tests should be employed judiciously and be reserved for children who are most likely to derive measurable benefit, such as those likely to have peptic ulcer disease. At this time a test and treat strategy in children cannot be considered prudent, evidence based or cost effective. It is appropriate to limit diagnosis and treatment to children and adolescents in whom H pylori has been identified during endoscopic investigation.

Diet fat and oral insulin-like growth factor influence the membrane fatty acid composition of suckling rat small intestine

BACKGROUND

Insulin-like growth factor- plays an important role in small intestine development. The presence of insulin-like growth factor-1 and the complexity of the fatty acid composition in breast milk suggests that intestinal development may be influenced by manipulating the levels of these components.

METHODS

To determine whether a physiological dose of insulin-like growth factor-1 would influence sucrase and lactase activity levels, 10-day-old suckling rat pups were treated with an oral gavage of insulin-like growth factor-1. Four diets differing in fat composition were fed to lactating dams. Brush border membranes were isolated from jejunal and ileal segments of suckling rat small intestine. Fatty acid analysis of choline and ethanolamine phospholipids was performed.

RESULTS

Insulin-like growth factor-1 was found to have no effect on the sucrase and lactase activities of suckling rats. Changes in the diet fat composition of the mother's diet indirectly influenced the fatty acid composition of suckling rat small intestine. Insulin-like growth factor-1 decreased ileal C20:4n-6 levels. A correlation was observed between lactase activity and C20:4n-6 and C22:6n-3 levels. As C20:4n-6 levels increased, lactase activity appeared to decline. Increased lactase activity was observed when C22:6n-3 levels increased.

CONCLUSIONS

The changes observed in C20:4n-6 levels in response to oral insulin-like growth factor-1, combined with the apparent trend of increased lactase activity with declining levels of C20:4n-6, may be of significance in the development of the small intestine in early life.

Canadian Helicobacter pylori Consensus Conference update: infections in adults. Canadian Helicobacter Study Group

The first Canadian Helicobacter pylori Consensus Conference took place in April 1997. The initial recommendations of the conference were published in early 1998. An update meeting was held in June 1998, and the present paper updates and complements the earlier recommendations. Key changes included the following: the recommendation for testing and treating H pylori infection in patients with known peptic ulcer disease was extended to testing and treating patients with ulcer-like dyspepsia; it was decided that the urea breath test (not serology) should be used for routine diagnosis of H pylori infection unless endoscopy is indicated for another reason; and recommended therapies were a twice daily, seven-day regimen of a proton pump inhibitor (omeprazole 20 mg, lansoprazole 30 mg, pantoprazole 40 mg) or ranitidine bismuth citrate 400 mg, plus clarithromycin 500 mg and amoxicillin 1000 mg, or plus clarithromycin 500 or 250 mg and metronidazole 500 mg. The need was reiterated to have funding for readily accessible, accurate testing for H pylori infection with the urea breath test. It was strongly recommended that regional centres be established to monitor the prevalence of antibiotic-resistant H pylori infections. The initial consensus document referred to pediatric issues that were not addressed in this update but were the subject of a subsequent Canadian Helicobacter Study Group meeting, and will be published later in 1999.