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Biomedical subjects

R H Hunt

Publications and source records attributed to R H Hunt.

At least 19 recordsLinked to original sources
PubMed1992

Effect of acupuncture on gastric acid secretion in healthy male volunteers.

Six randomized, placebo controlled studies were performed to investigate the effect of electroacupuncture on gastric acid output in 38 healthy males. Electroacupuncture decreased basal acid output when compared to placebo acupuncture [from 3.50 +/- 0.59 mmol/hr to 2.54 +/- 0.56 mmol/hr (P < 0.05)] as well as sham feeding-stimulated acid output [from 18.52 +/- 2.25 mmol/hr to 5.38 +/- 2.11 mmol/hr (P < 0.005)], but had no effect on the pentagastrin stimulated acid output. The inhibitory effect of acupuncture on sham feeding-stimulated acid output was not affected by local anesthesia of the acupoint, but was prevented by a prior intravenous naloxone injection. Acupuncture did not alter plasma gastrin levels (20.7 +/- 7.6 micrograms/liter, vs control 21.2 +/- 7.2 micrograms/liter) but naloxone increased it (26.1 +/- 14.5 micrograms/liter) (P < 0.05). We conclude that the antisecretory effects of electroacupuncture do not result from decreased gastrin release or decreased parietal cell sensitivity to gastrin, but are mediated through naloxone-sensitive opioid neural pathways and vagal efferent pathways.

Acupuncture Points↗
PubMed1992

Mucosal damage during intestinal anaphylaxis in the rat. Effect of betamethasone and disodium cromoglycate.

In this study, two antiallergic compounds, betamethasone and disodium cromoglycate were tested in an animal model of intestinal anaphylaxis. Rats, immunized with Nippostrongylus brasiliensis, were challenged intravenously with whole worm antigen or saline. Antigen challenge resulted in significant abnormalities: epithelial damage with shorter villi, decreased activity of digestive enzymes, decreased levels of mucosal histamine, a mast cell mediator, and increased blood uptake of [51Cr]EDTA from the lumen. Low-dose betamethasone, 24 and 48 hr before antigen, was not effective in preventing the effects: villus damage and increased [51Cr]EDTA uptake were seen, although mucosal mast cell numbers were significantly reduced by the drug. High-dose betamethasone completely prevented intestinal anaphylaxis: villus height, digestive function, and [51Cr]EDTA recovery in antigen-challenged animals were not significantly different from controls. Mucosal histamine levels and mast cells were significantly reduced in the high dose betamethasone group. Oral disodium cromoglycate did not prevent the abnormalities but provided a slight beneficial effect.

Analysis of Variance↗
PubMed1992

Role of T lymphocytes in intestinal mucosal injury. Inflammatory changes in athymic nude rats.

To determine the role of T cells versus mast cells in mucosal injury, we documented structural and functional changes in the intestine of congenitally athymic nude rats during infection with the enteric parasite, Nippostrongylus brasiliensis. Studies were conducted at days 4, 7, 10, and 21 postinfection; controls were uninfected. Villus damage was indicated by morphological abnormalities at days 7, 10, and 21 and reduced activities of disaccharidase enzymes at days 10 and 21. The activity of the proliferative enzyme, thymidine kinase, was increased only at day 21, at which time the crypts were elongated. Epithelial permeability increased significantly: 5-hr recovery (in urine and blood) of the probe molecule, [51Cr]EDTA, following injection into ligated jejunal segments, was elevated at days 7 and 10. Uptake of a protein antigen, ovalbumin, from lumen to blood followed a similar pattern. No evidence of functional T cells was demonstrated. However, mucosal mast-cell activation was indicated by elevated serum levels of rat mast-cell protease II at days 7 and 10. We conclude that the absence of thymus-derived T cells does not preclude mucosal damage involving impaired barrier and digestive function. Mucosal mast cells may be involved in causing the injury in this model.

Animals↗
PubMed1992

Effects of misoprostol on the pharmacokinetics of indomethacin in human volunteers.

The effects of misoprostol (200 micrograms as a single dose or q.i.d. as a multiple dose) on the pharmacokinetics of indomethacin (100 mg single-dose administration or 50 mg t.i.d. multiple-dose administration) were studied in 16 healthy human volunteers under single-dose and steady-state conditions in a randomized, double-blind, placebo-controlled, balanced three-period study design. The overall absorption as shown by the values for area under the concentration curve of indomethacin was unaffected by concurrent administration of misoprostol. However, misoprostol did significantly enhance the steady-state maximum concentration of indomethacin by 32%. Thus misoprostol does not interfere with the absorption of indomethacin despite the known inhibitory effects of this protaglandin analog on acid secretion.

Administration, Oral↗
PubMed1992

Omeprazole (20 mg) daily given in the morning or evening: a comparison of effects on gastric acidity, and plasma gastrin and omeprazole concentration.

Although omeprazole has a long duration of action and has usually been given in the morning, there are theoretical advantages in administering antisecretory drugs in the evening as has been shown for the H2-receptor antagonists. The aim of this study was to compare the effects of placebo and 20 mg omeprazole given either in the morning or evening, on gastric acidity, plasma gastrin levels and plasma omeprazole in 6 duodenal ulcer patients. The 24-hour mean pH (+/- S.E.M.) was: placebo 1.7 +/- 0.1; morning doing, 3.9 +/- 1.8 (P less than 0.01); evening dosing, 2.9 +/- 1.1 (N.S.). There was a large inter-individual variability of intragastric acidity in response to omeprazole, which was reflected both in the plasma gastrin and in the area under the plasma omeprazole concentration-time curve. Morning administration of omeprazole is optimal, but variability in the patient response to 20 mg omeprazole is still seen.

Double-Blind Method↗
PubMed1992

Effects of chronic left vagal stimulation on visceral vagal function in man.

We examined the effects of chronic left vagal electrostimulation on afferent and efferent gastrointestinal vagal function in eight patients. Afferent function was assessed using cortical evoked responses to electrical stimulation of the esophagus and to direct vagal stimulation using the implanted left vagal electrode. Efferent gastrointestinal vagal function was measured by examining the basal, maximal, and sham fed stimulated gastric acid output prior to and with chronic left vagal electrostimulation. Esophageal electrostimulation produced a cortical evoked response consisting of three negative and three positive peaks within 400 msec after stimulation. Prior to vagal electrostimulation the mean conduction velocity of the afferent signal was measured at 8.72 +/- 3.39 m/sec, compatible with A-delta fibers involvement. Basal, maximal, and sham fed acid output were 1.11, 21.87, and 9.37 mmol/hour, respectively. The evoked response to esophageal electrical stimulation was not changed with chronic left vagal electrostimulation. Direct vagal stimulation also produced evoked potentials that were comparable to those obtained with esophageal stimulation. The mean conduction velocity was 6.26 +/- 2.72 m/sec (NS) so that there was no evidence of loss of myelinated fibers with chronic stimulation. No differences were detected in basal (1.29 mmol/h), maximal (21.64 mmol/h), or sham fed stimulated (8.03 mmol/h) acid output, showing that vagal electrostimulation has no effect on either total or vagally mediated acid output, an efferent vagal function. In conclusion, chronic left vagal electrostimulation has no significant adverse effect on gastrointestinal vagal function.

Adult↗
PubMed1992

Evidence of impaired afferent vagal function in patients with diabetes gastroparesis.

Two patients, a 28-year-old male and a 70-year-old female, with chronic insulin dependent diabetes mellitus and evidence of autonomic neuropathy were studied using cortical evoked responses following esophageal balloon and electrical stimulation. Both patients had symptomatic gastroparesis, poor gastric emptying, and reduced gastroduodenal motility including abnormal results of scintigraphy and manometry. There was slowing of afferent vagal conduction but good evoked potential responses were recorded even though one patient could not feel electrical stimulation of either the proximal or distal esophagus. It is improbable that the gastric symptoms are due to an afferent autonomic neuropathy, but symptoms may well be related to impairment of motor vagal pathways. Nevertheless, afferent vagal pathways are involved in severe diabetes mellitus. The clinical significance of this delay in conduction velocity of afferent pathways remains to be established.

Adult↗
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↗
PubMed1990

Acid and barriers. Current research and future developments for peptic ulcer therapy.

Medical therapy for peptic ulcer disease has been targeted at inhibiting acid secretion based on the belief that ulcers occur due to an imbalance between aggressive and protective factors. New antisecretory agents are unlikely to show any dramatic improvement over the success and safety of histamine H2 receptor antagonists or the recently introduced H+K+ATPase proton pump antagonist omeprazole. The development of specific muscarinic M3 and gastrin receptor antagonists will provide useful agents to suppress acid and pepsinogen secretion by alternative means and may prevent the associated hypergastrinaemia seen with anti-secretory therapy. Enhancement of mucosal defence by site protective agents will be based on a better understanding of the vascular and immune factors involved in maintaining mucosal integrity and the growth factors that regulate wound healing. Molecular techniques are likely to produce the 'model anti-ulcer' agent which will effectively inhibit acid secretion and also enhance wound healing thus providing a cure for this chronic disease.

Antacids↗
PubMed1979

Controlled comparison of cimetidine and carbenoxolone sodium in gastric ulcer.

Fifty-four outpatients with endoscopically diagnosed benign gastric ulcer were allocated at random to treatment with either cimetidine 800 mg daily for six weeks or carbenoxolone sodium 300 mg daily for one week then 150 mg daily for five weeks. Ulcers were reassessed by endoscopy at the end of the trial. The endoscopist was unaware of the treatment and did not take part in the clinical care of the patients. Twenty-one of the 27 patients (78%) given cimetidine and 14 of the 27 (52%) given carbenoxolone had healed ulcers. Symptomatic response occurred earlier with cimetidine but was not significantly better. Unwanted effects were more common in the carbenoxolone group: 12 patients developed hypokalaemia, four of whom needed oral potassium supplements. The results suggest that histamine H2-receptor blockade is at least as effective as carbenoxolone sodium for benign gastric ulcer and produces fewer side effects.

Administration, Oral↗