The Anopheles gambiae complex: a new species from Ethiopia

Historically, members of the Anopheles gambiae complex from Ethiopia have been identified chromosomally as either A. arabiensis or A. quadriannulatus. Recent collections from the Jimma area in Ethiopia, southwest of Addis Ababa, revealed 29 specimens of A. quadriannulatus based on the standard polymerase chain reaction (PCR) identification method. 'Wild' females were induced to lay eggs and the progeny reared as individual families. Resulting adults were cross-mated to a laboratory colony strain of A. quadriannulatus originating from the Kruger National Park, South Africa. Hybrid progeny were obtained only from the colony female x Ethiopian male cross. This cross produced a female/male sex ratio of 0.48. Male offspring were sterile and ovarian polytene chromosomes from hybrid females showed typical asynapsis as expected in interspecific crosses within the A. gambiae complex. The X chromosomes, although apparently having homosequential banding patterns, were usually totally asynapsed. All autosomes were homosequential. The lack of inversion heterozygotes, in both the wild and hybrid samples, may simply be a reflection of the small sample size. Until such time as the Ethiopian species can be formally described and assigned a scientific name, it is provisionally designated Anopheles quadriannulatus species B because of its close similarity to this species.

The role of four anopheline species (Diptera: Culicidae) in malaria transmission in coastal Tanzania

Malaria is holoendemic in coastal Tanzania with Anopheles funestus and members of the A. gambiae complex being mainly responsible for transmission. Over a 4 months' sampling period 2222 anopheline mosquitoes were collected using light-traps and indoor resting catches, of which 58.6% were A. gambiae, 7.6% A. arabiensis, 6.9% A. merus and 26.9% A. funestus. Plasmodium falciparum circumsporozoite antigen (CSA) rates were: A. funestus 6.05% (n = 479), A. gambiae 8.4% (n = 1042), A. arabiensis 7.3% (n = 136) and A. merus 9.8% (n = 122). The P. malariae CSA rate for all anophelines was 0.07% (n = 1862). Estimated sporozoite densities were less than 2000 for at least 50% of all the positive mosquitoes. Along the coast the abundance of A. merus (41.3%) and A. gambiae (46.1%) was similar, and their CSA rates were comparable (11.6% and 12.5%, respectively) and higher than those for A. arabiensis (7.7%) and A. funestus (4.6%). These results indicate that A. merus plays an unexpectedly important role in malaria transmission in coastal Tanzania.

Helicobacter pylori: from art to a science

Helicobacter pylori infection is widely prevalent especially in developing countries. Increasing knowledge of the pathophysiology associated with H. pylori is leading to an understanding of the mechanisms of mucosal inflammation and gastritis and how this leads to peptic ulcer disease, gastric mucosal associated lymphoid tissues (MALT), lymphoma and gastric cancer. More accurate diagnostic testing for the infection is now possible with both endoscopic and non-endoscopic tests to identify patients most appropriate for eradication therapy. Modern treatments tend to overcome the problems of metronidazole resistance and compliance seen with two week bismuth triple therapy and widely studied is a proton pump inhibitor given with clarithromycin and amoxicillin or metronidazole for one week. These achieve amongst the highest eradication rates and have also been shown to be cost effective. This paper reviews these recent advances and addresses areas of clinical interest and future directions.

Adding once-daily omeprazole 20 mg to metronidazole/amoxicillin treatment for Helicobacter pylori gastritis: a randomized, double-blind trial showing the importance of metronidazole resistance

OBJECTIVE

We compared the Helicobacter pylori eradication rate after a 14-day treatment with amoxicillin 500 mg t.i.d. and metronidazole 500 mg t.i.d. with or without omeprazole 20 mg once daily.

METHODS

This was a randomized, controlled trial in which omeprazole was given in double-blind fashion. Patients with H. pylori-associated gastritis were enrolled in four centers in Canada from July 1991 to January 1994. Eradication of H. pylori was assessed by histological evaluation and culture of endoscopic biopsies obtained from the antrum and corpus of the stomach.

RESULTS

The H. pylori eradication rate was 73% (33 of 45) in the omeprazole-amoxicillin-metronidazole group, compared with 66% (31 of 47) in the amoxicillin-metronidazole group. This 7% difference was not statistically significant (p = 0.43, 95% confidence interval for difference -11% to 26%). Metronidazole primary resistance in the prestudy cultures was found more frequently in the omeprazole-amoxicillin-metronidazole group than in the amoxicillin-metronidazole group. Resistance to metronidazole was an important predictor of treatment failure. The H. pylori eradication rate was 61% (19 of 31) for patients infected with metronidazole-resistant H. pylori strains, compared with 91% (30 of 33) eradication for those infected with metronidazole-sensitive strains (p < 0.01). Vaginal candidiasis was reported in four patients.

CONCLUSIONS

The H. pylori eradication rate was higher (73%) for omeprazole-amoxicillin-metronidazole than for the dual antibiotic therapy given without omeprazole (66%); however, this difference was not statistically significant. Metronidazole resistance significantly reduces H. pylori eradication rates.

A Canadian physician survey of dyspepsia management

OBJECTIVE

To determine the management of patients with new onset dyspepsia by Canadian family physicians.

METHODS

A survey was mailed to 195 family physicians in August 1995 to identify how they manage dyspepsia in patients according to four scenarios: based on presenting symptoms alone; assuming Helicobacter pylori-positive; known to be H pylori-negative; and endoscopically confirmed nonulcer dyspepsia.

RESULTS

A total of 170 of 195 physicians (87.2%) completed the survey. Physicians reported that 7.3% of their practice is devoted to dyspepsia and 23% of these dyspeptic patients present for the first time. Ninety-three per cent of family physicians find a symptom classification of ulcer-, reflux- and dysmotility-like dyspepsia helpful. The majority of patients are advised to make life-style changes and are treated with antacids or empiric drug therapy. A H2 receptor antagonist was the drug of choice for ulcer and reflux-like dyspepsia, while prokinetics were often used for reflux and dysmotility-like dyspepsia. After failure of initial treatment, patients were given another course of empiric treatment, commonly with cisapride or omeprazole. Family physicians estimated that the mean time to obtain a gastrointestinal consult was five weeks, and 70% indicated that this time to consult adversely influenced their decision to refer. If this time was reduced to less than two weeks, responding physicians would consider referring all eligible patients. On average, two to 2.5 courses of empiric therapy were given before referral. If H pylori status was known, fewer empiric treatments (mean 1.8) were given before gastroenterological referral compared with the other scenarios. If the patient had nonulcer dyspepsia, 30% of family physicians provided reassurance only and did not prescribe empiric drug treatment.

CONCLUSIONS

Most newly dyspeptic patients in Canada are treated with empiric therapy according to symptom classification and referred for endoscopy after an average two to 2.5 treatment courses.

Eradication of Helicobacter pylori infection in the management of patients with dyspepsia and non-ulcer dyspepsia

Although H. pylori infection has been recognized as a major etiological agent for the development of chronic active gastritis, duodenal ulcer and benign non-NSAID related gastric ulcer, its role in the development of symptoms in patients with dyspepsia remains uncertain. Results from population-based epidemiological studies have been conflicting regarding a causal link between H. pylori infection and dyspepsia. Abnormalities in gastric acid secretion may exist in some dyspeptic patients. Whether disordered gastric motility seen in dyspeptic patients is related to the infection is not clear based on the results in the literature. Numerous clinical trials have been undertaken to eradicate H. pylori infection and improve the symptoms in dyspeptic patients; however, the results have been discrepant between studies. Many published studies suffer from methodological problems that have made interpretation difficult. Large, well-conducted, randomized, placebo-controlled, clinical trials with long-term follow-up are needed to justify the beneficial effect of H. pylori eradication treatment in dyspeptic patients seen in some small studies. H. pylori eradication therapy is cost-effective in H. pylori-infected dyspeptic patients although this benefit may take a long time to accrue, especially in younger patients.

What role does Helicobacter pylori play in dyspepsia and nonulcer dyspepsia? Arguments for and against H. pylori being associated with dyspeptic symptoms

A major role for Helicobacter pylori gastritis in nonulcer dyspepsia (NUD) is controversial. Gastroduodenal dysfunction may be associated with H. pylori infection, but there is little evidence for a causal link with dyspepsia. Population-based studies with appropriate methodology have generally failed to confirm an association between H. pylori and NUD. Furthermore, no definite association between subgroups of NUD (ulcer-like, dysmotility-like, reflux-like, and nonspecific) and H. pylori has been identified however the subgroups have been defined, and no specific symptom pattern characterizes patients with H. pylori infection. Whether H. pylori-induced alterations of gastric physiology can explain NUD remains open to debate while we await the results of more specific experiments. Although acid secretion in response to gastrin-releasing peptide may be increased in a subset of NUD patients who are infected with H. pylori, uninfected patients with NUD have not been assessed and the results require confirmation. Most studies suggest no association between H. pylori and gastroduodenal motor or sensory dysfunction in NUD. Treatment trials have been unconvincing. The trials with bismuth therapy have not been adequately blinded. Furthermore, some studies suggest that H. pylori-negative patients with NUD may respond to bismuth treatment, although the results have not been uniform. Therapies aimed at curing H. pylori infection have produced mixed results, with small positive and negative trials. The trials that have used adequate outcome measures have more often than not been negative. Based on current evidence, H. pylori is not established to be of causal importance in NUD.

Review and analysis of the effects of olestra, a dietary fat substitute, on gastrointestinal function and symptoms

Olestra, a dietary fat substitute, was recently made available to consumers in savory snacks in three cities. Early reports of gastrointestinal complaints attributed to olestra attracted media coverage and fostered confusion among physicians and consumers about the nature of olestra and its effects on the digestive system. We reviewed all published studies of olestra's gastrointestinal effects and all relevant unpublished studies submitted to the Food and Drug Administration. Each study was analyzed by a group of expert gastroenterologists and epidemiologists. The symptoms reported with olestra ingestion are similar to those reported with ingestion of fiber and sorbitol, although the mechanisms involved in changing stool characteristics differ among these food additives. Olestra's effects on stool habit and characteristics are due to its presence in the stool. Large amounts are more likely to induce gastrointestinal symptoms than small amounts. There is no evidence that olestra induces pathological change in bowel function: there is no increased fluid or electrolyte nor is there altered gastrointestinal motility or microflora. Olestra and triglyceride ingestion resulted in a similar frequency of symptoms in normal adults and children and in people with chronic inflammatory bowel disease in remission. Olestra traverses the digestive tract intact to become a stool additive. Some subjects develop a change in bowel habit and stool characteristics due to the presence of more olestra in the stool. These changes resemble those associated with ingestion of sorbitol and fiber.

The Second Canadian Consensus Conference on the Management of Patients with Gastroesophageal Reflux Disease

The Second Canadian Consensus Conference on the Management of Patients with Gastroesophageal Reflux Disease (GERD) was organized by the Canadian Association of Gastroenterology to address major advances in the understanding of the pathophysiology of GERD, to review the new methods of investigation and therapy introduced since the first conference in 1992 and to examine the issue of relevant health economics. The changes that have taken place over the past four years have been sufficiently dramatic to necessitate reassessment of the recommendations made following the first conference. The second conference dealt with the investigation and treatment of uncomplicated GERD and the complex issues of esophageal and extraesophageal complications such as chest pain, Barrett's esophagus, and reflux-related pulmonary and laryngeal disorders. The role of laparoscopic surgery was also discussed. A decision tree for investigation and treatment of patients with GERD was developed. The 38 participants represented a broad spectrum of experience, location of practice and special interests. The distribution of participants conformed to the recommendations of the Canadian Medical Association guidelines for consensus documents in that there should be input from all possible interested parties. A list of the state-of-the-art lectures presented during the conference, the small group sessions, the session chairpersons and participants are appended to this document. CONCLUSIONS. UNCOMPLICATED GERD: GERD with alarm symptoms must be investigated immediately. There was no consensus about when to investigate uncomplicated GERD, ie, whether to perform endoscopy immediately or after initial therapy fails. There was controversy regarding 'step up' (H2 receptor antagonist [H2RA] or prokinetic [PK] first therapy) versus 'step down' therapy (proton pump inhibitor [PPI] first therapy). The majority decision was for short term 'step up' therapy and investigation if symptoms do not improve or recur. Maintenance therapy should be carried out with the initial therapy that was effective. H2RAs and PKs may suffice for maintenance therapy in milder GERD; however, for severe esophagitis, PPIs should be used.

SURGERY

Indications for laparoscopic surgery should be the same as for conventional antireflux operations. NONCARDIAC ANGINA-LIKE CHEST PAIN: After exclusion of nonesophageal causes, the majority decided that eight weeks of therapy with a PPI should be performed, while some suggested work-up before a therapeutic test. In the absence of response or recurrence, esophagogastroduodenoscopy (EGD) and, depending on the circumstances, 24 h ambulatory pH/motility may be indicated. BARRETT'S ESOPHAGUS: Only patients who, in case of future discovery of cancer or dysplasia, are able or willing to undergo therapy should have surveillance. In the absence of dysplasia EGD should be performed every two years, and in the presence of mild dysplasia every three to six months. All agreed that for severe dysplasia, esophagectomy or poor risk patients, esophageal mucosal ablation is indicated. ESTRAESOPHAGEAL COMPLICATONS (EECs): Asthma, chronic cough and posterior laryngitis were considered EECs. Although PPIs may decrease symptoms, improvement alone is not diagnostic of the presence of EEC. Ambulatory pH studies with two pH probes or ambulatory pH/motility may be useful in establishing causation.

HEALTH ECONOMICS

There are limited data for an economic comparison among the different drugs or between medical and surgical therapy.

Ribosomal DNA-polymerase chain reaction assay discriminates between Anopheles quadriannulatus and An. merus (Diptera: Culicidae)

A ribosomal DNA polymerase chain reaction technique (rDNA-PCR) that distinguishes the 5 more common and widespread members of the Anopheles gambiae complex failed to consistently identify specimens of Anopheles merus Dönitz collected in South Africa and Tanzania. When the original rDNA-PCR assay was applied to field-collected specimens or specimens from laboratory colonies established from these populations, bands diagnostic of both An. merus and An. quadriannulatus (Theobald) were amplified from all individual specimens. However, all the specimens tested had the polytene chromosome banding morphology or the superoxide dismutase isozyme that were diagnostic for An. merus. Replacement of the original An. quadriannulatus-specific primer with a new primer derived from another region of the rDNA intergenic spacer resulted in an alternative rDNA-PCR assay that accurately and consistently differentiated among specimens of An. merus, An. quadriannulatus, and An. arabiensis Patton. Anopheles gambiae Giles also may be distinguished by this assay if high percentage agarose gels or gels of other matrices with better resolving powers are used.

Controversial issues in gastroesophageal reflux disease

The management of gastroesophageal reflux disease (GERD) has advanced dramatically in the past 20 years because of increased understanding of its pathophysiology and improvements in available treatments. A number of important new ideas arousing controversy include the place of over-the-counter H2 receptor antagonists; the role of endoscopy in diagnosis of reflux symptoms; initial treatment options with regard to stepping up therapy to the most effective as needed or stepping down therapy from a proton pump inhibitor given initially because of its superior efficacy in all grades of reflux disease; the optimal choice of long term management of patients with GERD or GERD complicated by Barrett's metaplasia; the risk of Barrett's metaplasia; and the role of surveillance of this population. This paper reviews these topics and addresses the controversial issues.

The comparative effects of lansoprazole, omeprazole, and ranitidine in suppressing gastric acid secretion

The effects on 24-hour intragastric pH levels of once-daily doses of lansoprazole 15 mg and lansoprazole 30 mg were compared with the effects of omeprazole 20 mg QD and ranitidine 150 mg QID in a phase I, randomized, double-masked, four-way crossover study conducted in 29 healthy male volunteers. Subjects received each treatment regimen for 5 consecutive days with at least a 2-week washout between treatment periods. Ambulatory 24-hour intragastric pH values were monitored in each subject at baseline (2 days before crossover period 1) and again before dosing on day 5 of each of the four crossover treatment periods. Gastric pH values increased during all four regimens, with significantly higher mean 24-hour pH values noted in subjects receiving lansoprazole 30 mg QD (4.53 +/- 0.16) compared with those receiving lansoprazole 15 mg QD (3.97 +/- 0.16), omeprazole 20 mg QD (4.02 +/- 0.16), or ranitidine 150 mg QID (3.59 +/- 0.16). Lansoprazole 30 mg produced significantly greater mean percentages of time that the gastric pH was above 3.0 and 4.0 (75% and 63%, respectively) compared with the other treatment regimens. The mean percentages of time during which gastric pH was above 3.0 and 4.0, respectively, for the other treatments were lansoprazole 15 mg, 64% and 48%; omeprazole 20 mg, 63% and 51%; and ranitidine 150 mg, 52% and 38%. All treatment regimens were well tolerated, with no clinically significant differences between the regimens. Multiple-dose lansoprazole 30 mg QD produced a significantly increased intragastric pH level and significantly longer durations of increased intragastric pH level compared with lansoprazole 15 mg QD, omeprazole 20 mg QD, and ranitidine 150 mg QID.

Review: eradication of Helicobacter pylori. Problems and recommendations

The successful isolation of Helicobacter pylori from stomachs of patients with gastritis and peptic ulcer has revolutionized our concepts of the pathogenesis of gastritis, peptic ulcer, gastric cancer and gastric B cell lymphoma. Eradication of H. pylori heals gastritis and H. pylori-related peptic ulcer. After a successful cure of H. pylori infection, virtually no recurrence of duodenal ulcer is seen. However, treatment to cure the infection has proved difficult. Numerous clinical trials have been attempted, but as yet no ideal regimen has been identified. Monotherapies have many drawbacks and should be avoided. Dual therapies combining a proton pump inhibitor (PPI) and an antimicrobial agent provide higher eradication rates than those involving two antimicrobial agents. Bismuth-based triple therapies are more effective than dual therapies in eradicating H. pylori infections. However, poor compliance and frequent adverse effects have made these combinations less favourable in clinical practice. Proton pump inhibitor-based triple therapies have shown more consistent and higher eradication rates with a short duration of treatment, good patient compliance, fewer side effects, prompt symptom relief and fast ulcer healing. Results from PPI-based quadruple therapies are promising; however, large multicentre clinical trials are needed to confirm the effect and the complex regimen again may compromise compliance outside of the clinical trial setting. Eradication of H. pylori infection is cost-effective in the long-term management of peptic ulcer disease compared with maintenance therapy with antisecretory drugs.

Speed of healing and symptom relief in grade II to IV gastroesophageal reflux disease: a meta-analysis

BACKGROUND & AIMS

Esophagitis healing proportions are often incorrectly called the healing rate. The aim of this study was to compare different drug classes by expressing the speed of healing and symptom relief through a new approach.

METHODS

A fully recursive literature search to July 1996 identified 43 articles on gastroesophageal reflux disease (GERD) (7635 patients) meeting strict inclusion criteria: single- or double-blind randomized studies in adults with endoscopically proven erosive or ulcerative esophagitis. For each drug class, linear regression analysis estimated the average percentage of patients who were healed and heartburn free per week.

RESULTS

Mean overall healing proportion irrespective of drug dose or treatment duration (< or =12 weeks) was highest with proton pump inhibitors (PPIs; 83.6% +/- 11.4%) vs. H2-receptor antagonists (H2RAs; 51.9% +/- 17.1%), sucralfate (39.2% +/- 22.4%), or placebo (28.2% +/- 15.6%). Correcting for patients without baseline heartburn, the mean heartburn-free proportion was highest with PPIs (77.4% +/- 10.4%) vs. H2RAs (47.6% +/- 15.5%). PPIs showed a significantly faster healing rate (11.7%/wk) vs. H2RAs (5.9%/wk) and placebo (2.9%/wk). PPIs provided faster, more complete heartburn relief (11.5%/wk) vs. H2RAs (6.4%/wk).

CONCLUSIONS

More complete esophagitis healing and heartburn relief is observed with PPIs vs. H2RAs and occurs nearly twice as fast. This semiquantitative expression of speed of healing and symptom relief permits comparisons for future economic evaluation and quality-of-life assessments.

Helicobacter pylori: new developments and treatments

The authors highlight new developments in research on Helicobacter pylori. There is now consensus that all patients with newly diagnosed or recurrent duodenal or gastric ulcers who have a positive test result for H. pylori should be treated for the infection. Patients presenting with complications of ulcers, such as bleeding, should also be treated. H. pylori has recently been classified as a definite human carcinogen by the International Agency for Research on Cancer. In treatment, new combination regimens, consisting of 3 or 4 different drugs, cure the infection in more than 80% of patients. Currently, the best combinations are: (1) omeprazole (or another proton-pump inhibitor), clarithromycin and metronidazole, (2) omeprazole (or another proton-pump inhibitor), clarithromycin and amoxicillin, (3) bismuth subsalicylate, tetracycline and metronidazole, and (4) omeprazole, bismuth subsalicylate, tetracycline and metronidazole.

Hormonal therapy for bleeding gastrointestinal mucosal vascular abnormalities: a promising alternative

Recurrent bleeding from an obscure gastrointestinal source is a common but often frustrating clinical challenge. Frequently these bleeds can be attributed to vascular anomalies in the upper or lower gastrointestinal tract. Traditional management has included surgical resection and endoscopic fulguration. However, these methods are often ineffective when vascular lesions are diffuse, difficult to identify, or endoscopically inaccessible. Hormone therapy with a combination of oestrogen and progesterone represents a promising alternative. Since initial reports of success in patients with epistaxis from hereditary haemorrhagic telangiectasia, growing evidence supports its role in reducing bleeding from gastrointestinal vascular anomalies. Existing literature is critically reviewed and management strategies incorporating hormone therapy are suggested.

Peptic ulcer disease: defining the treatment strategies in the era of Helicobacter pylori

Peptic ulcer disease continues to be a major health care problem costing the public billions of dollars each year. Recent evidence confirms a major role for Helicobacter pylori infection in the natural history of most cases of peptic ulcer disease. The most established and effective antibiotic treatment for the eradication of H. pylori has been the classic bismuth "triple therapy" regimen containing bismuth, metronidazole, and tetracycline. However, pretreatment resistance to metronidazole, poor compliance, and side effects have limited the widespread acceptance of bismuth triple therapy for routine use. Recent studies suggest that the combination of one or two antibiotic agents and a proton pump inhibitor offers a better tolerated regimen than bismuth triple therapy. Efficacy is similar with respect to eradication of H. pylori, and the combined use of a proton pump inhibitor assures rapid symptom relief and ulcer healing. Although the mechanisms by which H. pylori eradication is effected, the optimal dosing schedules, and the specific antimicrobial agents to be administered require further study, the combination of a proton pump inhibitor and one or two antibiotics promises to be an appropriate first-line treatment for peptic ulcer disease.

Effects of smoking on cure of Helicobacter pylori infection and duodenal ulcer recurrence in patients treated with clarithromycin and omeprazole

BACKGROUND

Smoking may affect adversely the cure rate for Helicobacter pylori infection in patients treated with amoxicillin and omeprazole. Therapy with clarithromycin and omeprazole was tested for its effectiveness in the treatment of H. pylori infection in smokers and nonsmokers.

MATERIALS AND METHODS

Patients with verified duodenal ulcer and H. pylori infection received clarithromycin 500 mg tid, in combination with omeprazole 40 mg/ day, for 2 weeks, followed by omeprazole (20 or 40 mg daily) for 2 additional weeks according to a randomized, double-blind, multicenter design. Patients were analyzed by their smoking status for the cure of H. pylori infection, ulcer healing, and prevention of duodenal ulcer recurrence.

RESULTS

After treatment with clarithromycin and omeprazole, H. pylori infection was cured in 71% of the smokers and in 77% of the nonsmokers (evaluated 4-6 weeks after treatment). Overall ulcer healing was 95%, and overall ulcer recurrence was 19%. For H. pylori-negative patients, ulcer recurrence was 12% in both smokers and nonsmokers. None of these values was significantly different when smokers were compared to nonsmokers.

CONCLUSIONS

Therapy with clarithromycin and omeprazole is effective for cure of H. pylori infection in smokers and nonsmokers. Smoking has no effect on duodenal ulcer healing or duodenal ulcer recurrence for patients treated with this regimen.

Modulation of neurocardiac function by oesophageal stimulation in humans

1. The heart and the oesophagus have similar sensory pathways, and sensations originating from the oesophagus are often difficult to differentiate from those of cardiac origin. We hypothesized that oesophageal sensory stimuli could alter neurocardiac function through autonomic reflexes elicited by these oesophageal stimuli. In the present study, we examined the neurocardiac response to oesophageal stimulation and the effects of electrical and mechanical oesophageal stimulation on the power spectrum of beat-to-beat heart rate variability in male volunteers. 2. In 14 healthy volunteers, beat-to-beat heart rate variability was compared at rest and during oesophageal stimulation, using either electrical (200 microns, 16 mA, 0.2 Hz) or mechanical (0.5 s, 14 ml, 0.2 Hz) stimuli. The power spectrum of beat-to-beat heart rate variability was obtained and its low- and high-frequency components were determined. 3. Distal oesophageal stimulation decreased heart rate slightly (both electrical and mechanical) (P < 0.005), and markedly altered heart rate variability (P < 0.001). Both electrical and mechanical oesophageal stimulation increased the absolute and normalized area of the high-frequency band within the power spectrum (P < 0.001), while simultaneously decreasing the low-frequency power (P < 0.005). 4. In humans, oesophageal stimulation, whether electrical or mechanical, appears to amplify respiratory-driven cardiac vagoafferent modulation while decreasing sympathetic modulation. The technique provides access to vagoafferent fibres and thus may yield useful information on the autonomic effects of visceral or oesophageal sensory stimulation.

Time to maximum effect of lansoprazole on gastric pH in normal male volunteers

BACKGROUND

The time to maximum inhibition of gastric acidity resulting from repeated oral dosing with lansoprazole 30 mg daily for 7 days was studied in nine healthy male volunteers.

METHODS

Twenty-four hour intragastric pH monitoring was performed before treatment and on days 1, 3, 5 and 7 of dosing with lansoprazole. Blood samples were taken for the estimation of plasma lansoprazole concentrations.

RESULTS

Lansoprazole 30 mg increased mean 24-h intragastric pH to 3.57 on day 1 compared with baseline mean pH of 2.11 (P < 0.05). The mean intragastric pH during the morning period (08.00-13.00 h) was significantly higher on days 3, 5 and 7 than on day 1, but no consistent differences between day 1, 3, 5 and 7 were noted for subsequent periods (13.00-18.00, 18.00-21.00 and 23.00-07.00 h). There were no differences in mean pH between days 3, 5 and 7. Intragastric pH was maintained above pH 3 for 54.7, 60.1, 61.9 and 67.4% of the time on days 1, 3, 5 and 7, respectively. Lansoprazole pharmacokinetic parameters did not change with daily dosing. The area under the lansoprazole plasma concentration-time curve correlated with the intragastric pH (P < 0.005).

CONCLUSIONS

Lansoprazole 30 mg raised intragastric pH significantly from baseline on day 1 to a maximum effect as early as 6 h after the first dose. The degree and duration of acid suppression confirm the usefulness of lansoprazole for the treatment of acid-related disorders.

Clinical economics review: cost-effectiveness of treatment alternatives for gastro-oesophageal reflux disease

Gastro-oesophageal reflux disease is a chronic recurring disorder, which is widespread, especially in Western societies. Faced with increasing health costs and finite resources, an increasingly important part of evaluating new treatments is economic appraisal. In this paper, we review critically the published economic studies of the cost-effectiveness of treatments for gastro-oesophageal reflux disease. Proton pump inhibitors are considered the best choice for the management of grades II-IV oesophagitis and are more cost-effective than H2-receptor antagonists because of their fast healing of oesophagitis, early relief of symptoms, and prevention of recurrent oesophagitis and development of complications.

Why guidelines are required for the treatment of Helicobacter pylori infection in children

Helicobacter pylori is firmly established as a human pathogen; it fulfils all of Koch's postulates as the infectious agent causing chronic, active (type B) gastritis. Infection is strongly associated with duodenal and gastric ulcer. Recently, gastric mucosal-associated lymphoid tissue lymphoma has been successfully treated by curing H. pylori infection. Because of the evidence that the organism causes chronic gastritis and an increased risk of gastric cancer, it has been classified as a category 1 carcinogen by the World Health Organization. However, the overwhelming majority of people infected have no symptoms. Current eradication therapy is not ideal; there are treatment failures and substantial side effects. As a result, therapy should be reserved for people with clinical symptoms and complications. The infection, if present, should be treated in patients who have endoscopic evidence of mucosal ulcers in the stomach or duodenum. Current evidence does not support treating the infection to prevent gastric carcinogenesis or to alleviate symptoms of abdominal discomfort in the absence of peptic ulcers.