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Biomedical subjects

R H Hunt

Publications and source records attributed to R H Hunt.

At least 145 records · Page 8Linked to original sources
PubMed1992

Role of gastric acid suppression in the treatment of gastro-oesophageal reflux disease.

Gastro-oesophageal reflux disease is a common condition with a complex pathophysiology. Despite the spectrum of abnormalities, gastric acid has a central role in mucosal damage, and the mainstay of medical treatment is suppression of gastric acid secretion. The results of antisecretory treatment as assessed by endoscopic healing are reviewed. H2 receptor antagonists give more rapid symptom relief than placebo and can produce endoscopic improvement in 31-88% of cases depending on the severity of oesophagitis. Complete healing, however, is seen only in 27-45% of patients and these have mainly grades I-II disease. Improved healing rates can be obtained by increasing the degree of acid suppression or the length of treatment. The addition of a prokinetic agent may be beneficial. Omeprazole heals 67-92% of patients overall and although most successful in the lower grades of oesophagitis, can also heal 48-62% of patients with grade IV disease. The degree and rate of healing seem to be related to the reduction in oesophageal acid exposure and thus may correlate with the degree and duration of acid suppression over 24 hours obtained by the various treatments. The underlying pathophysiology is unchanged, however, and long term treatment may be needed to maintain remission.

Gastric Acid↗
PubMed1992

Secretion of intravenously administered antibiotics in gastric juice: implications for management of Helicobacter pylori.

AIMS: To study whether differences in eradication rates of antibiotics may be explained by differences in secretion of antibiotics in gastric juice. METHODS: A single intravenous dose of either ampicillin 500 mg, erythromycin 500 mg, or metronidazole 500 mg was administered to four healthy Helicobacter pylori negative volunteers on different days. Antibiotic concentrations were measured in gastric juice before and every 10 minutes after administration of the drug for two hours and after one hour in serum. RESULTS: No ampicillin was detected in gastric juice. Erythromycin concentrations in gastric juice showed considerable individual variation and reached maximum concentrations of 2.2-4.8 mcg/ml between 30 and 80 minutes after dosing. Metronidazole concentrations in gastric juice showed much less individual variation and maximum concentrations of 5-6 mcg/ml were reached within 30 minutes and remained high during the study period. CONCLUSION: Metronidazole and erythromycin are secreted across the gastric mucosa, but ampicillin is not.

Adult↗
PubMed1992

Appropriate acid suppression for the management of gastro-oesophageal reflux disease.

Gastro-oesophageal reflux disease (GORD) results from an abnormally prolonged dwell time of acidic gastric contents in the oesophagus. Although GORD is primarily a motor disorder, the injurious effects of gastric acid are central to the pathogenic process of oesophagitis, and the severity of disease correlates with the degree and duration of oesophageal acid exposure. In the majority of patients with mild disease, oesophageal acid exposure occurs predominantly during post-prandial periods. Conventional doses of H2-receptor antagonists cannot overcome the integrated stimulus to acid secretion resulting from a meal, and are thus relatively ineffective in preventing daytime, post-prandial oesophageal acid exposure. In patients with more severe grades of oesophagitis, there are abnormally high levels of nocturnal acid exposure, with the intra-oesophageal pH being less than 4.0 for 36% of the time, compared with 5% of the time in patients with mild GORD. Control of nocturnal acid secretion thus becomes increasingly important. This may be made worse by relative gastric acid hypersecretion in some patients with severe GORD. The long duration of action and effective inhibition of meal-stimulated acid secretion probably explains the superiority of omeprazole in treating GORD. Preliminary meta-analysis shows that the healing rate of erosive oesophagitis at 8 weeks by antisecretory agents is directly related to the duration of suppression of gastric acid secretion achieved over a 24-hour period (r = 0.87; p less than 0.05).

Anti-Ulcer Agents↗
PubMed1992

The effect of acupuncture on gastrointestinal function and disorders.

Acupuncture has been used empirically in clinical practice in China for several millenia and has recently drawn interest as a mode of anesthesia. Despite extensive investigation, the exact mechanisms of its analgesic action are unknown, but are thought to involve endogenous opioid peptides. Only recently have studies attempted to evaluate the effect of acupuncture on gastrointestinal function and disease. A review of studies from both the Chinese and Western literature supports the efficacy of acupuncture in the regulation of gastrointestinal motor activity and secretion through opioid and other neural pathways. However, no firm conclusion can be drawn about the effectiveness of acupuncture in the treatment of specific gastrointestinal disorders because of the lack of properly randomized controlled trials.

Acupuncture Points↗
PubMed1992

Meta-analysis of the efficacy of antibiotic therapy in eradicating Helicobacter pylori.

Despite numerous Helicobacter pylori treatment studies, the optimum regimen(s) for its eradication remain unclear. Our objective was to determine systematically which regimen(s) gave the best pooled eradication rates, by using meta-analysis methodology. A total of 27 studies were identified. Pooled eradication rates for single (18.6%), double (48.2%), and triple therapy (82.3%) were statistically highly different (p < 0.0005). Eradication rates with amoxicillin (23.0%) and bismuth compounds (19.6%) were equivalent. Combined treatment with bismuth+metronidazole was better than bismuth+amoxicillin (55.1% vs. 43.7%, p = 0.049). Triple therapy with bismuth+metronidazole+tetracycline gave a statistically higher eradication rate (94.1%) than bismuth+metronidazole+amoxicillin (73.1%, p < 0.0005). Despite increased side effects with multiple antibiotic regimens, patients tolerated these well, without significant drop-out. The combination of bismuth, metronidazole, and tetracycline gives the best eradication rate, but the optimal doses and duration of treatment have yet to be determined. Further studies are necessary to explore factors such as antibiotic resistance and drug compliance as important factors affecting antibiotic efficacy.

Amoxicillin↗
PubMed1991

Treatment of peptic ulcer disease with sucralfate: a review.

Sucralfate has been used widely for the treatment of peptic ulcer. Healing rates for duodenal ulcer range from 60 to 90% at 4-6 weeks and up to 90% at 12 weeks for gastric ulcer. The small number of maintenance trials suggest that relapse of duodenal ulcer is reduced comparably to H2 receptor antagonists. There has been considerable interest in the possibility of lower relapse ratios after initial healing with sucralfate compared with H2 receptor antagonists, but more studies of the possible mechanisms as well as larger trials are still needed to confirm these observations.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1991

Helicobacter pylori and gastric acid secretion: the ulcer link?

Helicobacter pylori is a recognized cause of chronic active gastritis and is frequently associated with peptic ulcer disease, but its effect on acid secretion is unclear. Transient hypochlorhydria occurs with acute infections. Despite the theoretical possibility of an increase in parietal cell mass or a response to stimulation occurring secondary to the associated hypergastrinaemia observed with H. pylori, no consistent increase in basal, pentagastrin-stimulated acid secretion or 24-h intragastric acidity has been reported. Although H. pylori is accepted as one of the many factors involved in peptic ulcer disease, and eradication results in decreased ulcer recurrence, its pathogenic role is still poorly understood. The progression of chronic active gastritis to atrophic gastritis and hypochlorhydria may in part explain the natural tendency for duodenal ulcer disease to resolve.

Animals↗
PubMed1991

Aedes albopictus in Africa? First records of live specimens in imported tires in Cape Town.

Live larvae of Aedes albopictus have been found entering South Africa in used tire casings imported from Japan on 3 separate occasions. This is the first evidence that this mosquito is entering Africa and underlines the value of mosquito monitoring programs to detect the importations of this important vector. It is suggested that undetected populations of Ae. albopictus may have already become established in Africa.

Aedes↗
PubMed1990

Acid suppression.

Explore the source record for details and available documents.

Duodenal Ulcer↗
PubMed1990

The effect of naloxone on lipid-induced pyloric motor response in humans.

This study examines whether opioid receptors are involved in the mediation of the pyloric motor response to intraduodenal lipid infusion. Antral, pyloric, and duodenal manometry was performed in seven healthy volunteers with a sleeve/multiple side-hole manometric assembly. Triglyceride emulsion and normal saline were infused alternately into the duodenum through the manometric assembly for two 30-minute periods each. Naloxone was then administered as an IV bolus, 40 micrograms/kg, followed by an infusion of 60 micrograms.kg-1.h-1 that was continued during testing of the duodenal infusates. Before naloxone administration, intraduodenal lipid produced significant increases in the rate of isolated pyloric pressure waves and basal pyloric tone when compared with saline (P = 0.009 and 0.027, respectively). The pyloric motor responses were unchanged after administration of naloxone, indicating that in humans, naloxone-sensitive opioid mechanisms are not involved in the mediation of lipid-induced pyloric motor responses.

Adult↗
PubMed1990

Is there an optimal degree of acid suppression for healing of duodenal ulcers? A model of the relationship between ulcer healing and acid suppression.

The optimal degree and duration of suppression of gastric acidity required for the healing of peptic ulcers has never been established. Although very potent inhibitors of acid secretion are now available, the need for this degree of suppression has not been shown, and there is a possibility of adverse effects because of pronounced acid inhibition. Therefore, a model has been constructed that defines the relationship between duodenal ulcer healing and antisecretory therapy. Acid suppression data were obtained directly from investigators as raw data from 24-hour studies of acid secretion. Twenty-one experiments from seven investigators provided 490 24-hour studies using 19 different treatment regimens. Healing data were collected from a metaanalysis of published clinical trials of duodenal ulcer healing. A total of 144 published trials in 14,208 patients provided healing data at several endoscopic endpoints for the 19 drug regimens for which acidity data were provided. Weighted least-squares polynomial regression analysis was used to define those parameters of antisecretory therapy that contributed most to duodenal ulcer healing and to define the shape of the response surface. A highly significant correlation (r = 0.9814) was found between healing and the degree of acid suppression, the duration of acid suppression, and the length of therapy. The shape of the contour expression this relationship shows that healing increases as the duration of suppression increases and as gastric pH increases. However, suppression that increased pH beyond 3.0 was not found to increase ulcer healing further. It is concluded that a longer duration of antisecretory effect and/or a longer duration of therapy are of greater importance than potency for duodenal ulcer healing.

Antacids↗
PubMed1990

The susceptibility of five laboratory colonies of mosquitoes to the human nematode Wuchereria bancrofti (Cobbold).

Laboratory colonies of Anopheles gambiae, An. arabiensis, An. merus, An. quadriannulatus and Aedes aegypti formosus were artificially fed on blood containing microfilariae of Wuchereria bancrofti. The anopheline colonies all supported parasite development to the infective stage, with An. quadriannulatus being the most heavily infected. The parasite did not develop at all in the Ae. aegypti formosus colony.

Adult↗
PubMed1990

The relationship between suppression of acidity and gastric ulcer healing rates.

We have investigated the relationship between the suppression of acidity by antisecretory drugs for the treatment of benign gastric ulcer and their corresponding ulcer-healing rates. For a variety of antisecretory drug regimens, there was a significant correlation between suppression of 24-h intragastric acidity and ulcer healing rates after 2, 4 and 8 weeks of treatment. There was a lesser degree of correlation between healing and suppression of nocturnal acidity and the association between suppression of acidity and gastric-ulcer healing rates was less marked than that previously described for duodenal ulcer.

Antacids↗
PubMed1990

Twenty-four-hour intragastric acidity and nocturnal gastric secretion in gastric ulcer patients--the effects of cimetidine.

In a double-blind randomized study, the profile of 24-h intragastric acidity and nocturnal gastric secretion was measured in a group of patients with healed gastric ulcer on placebo and 400 mg cimetidine b.d. and 800 mg nocte. Neither cimetidine regimen significantly decreased daytime intragastric acidity, but the 800 mg nocte dose caused a significant decrease in both nocturnal acidity (18.1 to 5.5 mmol/L; P less than 0.05) and acid output (11.0 to 1.7 mmol 7 h; P less than 0.05). The decrease in nocturnal gastric secretion by 400 mg cimetidine b.d. was not significant. As in duodenal ulcer, 800 mg cimetidine nocte will effectively suppress night-time acid secretion in patients with gastric ulcer while leaving acid secretion during the day unaffected.

Adult↗
PubMed1990

Do hourly averaged pH readings correlate with those from point readings of aspiration? Comparison of two different electrode positions with simultaneous aspiration.

Hourly averaged data from continuous intraluminal pH recording were compared with the point aspiration in five 24-hour studies performed on healthy volunteers. Two different electrode positions were compared simultaneously with aspiration. The correlation was performed using the median from the whole hour's recording of the electrode against the aspiration point. There was a significant correlation between both electrodes and aspiration (p less than 0.001), although both electrodes read consistently lower than aspiration: electrode A (gastric antrum), median pH = 1.4; electrode B (gastric body), pH = 1.9; aspiration, pH = 2.3. These findings show that data reported in clinical trials using different recording techniques are not directly comparable and must be interpreted appropriately. The position of the electrode may also be important.

Adult↗
PubMed1990

Antigen-induced mucosal damage and restitution in the small intestine of the immunized rat.

Intestinal mucosal damage and restitution were examined following antigen-induced systemic anaphylaxis in Nippostrongylus brasiliensis immunized rats. The rats were injected intravenously with N. brasiliensis antigen or saline. At 60 min, morphological and biochemical parameters were determined in jejunum and ileum, and the epithelial permeability was assessed by measuring recovery of 51Cr-ethylenediaminetetraacetic acid in the blood after injecting it into a ligated segment. Antigen challenge resulted in significant abnormalities: (1) villus damage with sloughing of enterocytes; (2) decreased activities of brush border enzymes; (3) decreased levels of mucosal histamine and rat mast cell protease II (mast cell mediators), and (4) increased uptake of 51Cr-ethylenediaminetetraacetic acid. Progression of the injury was examined by taking consecutive biopsies at 15-min intervals for 60 min and then at 5 h. At 15 min, an abnormality was present in all sections which ranged from minor oedema and enterocyte detachment at villus tips to virtual complete destruction of the apical region. Restitution occurred by villus contraction with migration of the epithelium over the damaged regions. At 5 h, the epithelium had resealed, but the villi were significantly reduced in height.

Anaphylaxis↗