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Biomedical subjects

R H Hunt

Publications and source records attributed to R H Hunt.

At least 271 records · Page 15Linked to original sources

A study to examine agreement between endoscopy and histology for the diagnosis of columnar lined (Barrett's) esophagus.

Eleven subjects with a previous diagnosis of columnar lined esophagus and 12 control patients underwent esophagogastroduodenoscopy, including vital staining with Lugol's iodine and biopsy. Histology in 47 of 48 biopsies from controls agreed with endoscopic findings, and no patient had a columnar lined esophagus. Of 60 biopsies taken from study patients, the endoscopic appearance in 8 (13%) was not consistent with the histology. Good agreement was demonstrated between endoscopy and histology (kappa = 0.72). Compared with histology as the reference measure, the sensitivity, specificity, and accuracy of endoscopy were 89%, 93%, and 91%, respectively.

Adult↗

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.

Animals↗

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.

Animals↗

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.

2-Pyridinylmethylsulfinylbenzimidazoles↗

Sucralfate: the Bangkok review.

Sucralfate is a site-protective ulcer healing drug with a remarkable range of mechanisms of action. Recent studies highlight the capacity of sucralfate to bind basic fibroblast growth factor (bFGF) and deliver it in high concentration to the ulcer. Basic fibroblast growth factor stimulates the production of granulation tissue, angiogenesis and re-epithelization, thus improving the quality of ulcer healing. The effect of sucralfate in reducing parietal cell sensitivity may be another factor important in the lower relapse rate demonstrated after duodenal ulcer healing. Sucralfate has been demonstrated to be efficacious in healing both duodenal and gastric ulcers together with mild oesophagitis, and it is safe for both short-term use and maintenance. In stress ulcer prophylaxis it is as effective as acid suppression or neutralization and has the advantage of lesser rates of nosocomial pneumonia than are demonstrated with antacids or H2 antagonists. The potential advantages of sucralfate lie in the better quality of ulcer healing associated with longer duration of remission.

Clinical Trials as Topic↗

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.

Adult↗

The Second Canadian Gastroesophageal Reflux Disease Consensus: moving forward to new concepts.

Gastroesophageal reflux disease (GERD) is a disease with serious consequences that may result in significant impairment in quality of life and disease morbidity. Across all grades of severity of symptoms and severity of underlying esophageal disease, proton pump inhibitors (PPIs) provide therapeutic gains over prokinetics (PKs) or H2 receptor antagonists (H2RAs). The potential cost effectiveness of using medications with higher acquisition costs that may lower health care costs overall is often disregarded when conducting cost comparisons with medications having lower 'up-front' costs. Limiting therapy to less effective agents condemns many patients to protracted suffering, repeated physician visits and needless reinvestigation of symptoms that could have been resolved by appropriate initial therapy. Based on current data, use of any classification of symptom severity as a basis for selecting one class of therapeutic agents over another for first line therapy (i.e. PKs, H2RAs for 'mild' GERD, versus a PPI for 'severe' disease) is unwarranted.

Cost of Illness↗

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.

Chronic Disease↗

pH, healing rate, and symptom relief in patients with GERD.

Gastroesophageal reflux symptoms are common and occur in all of us from time to time. In others, reflux may be associated with ulcerative esophagitis. The symptoms may be aggravated by large meals, coffee, smoking and position. Physiological and pathological reflux can be separated by the frequency and duration of the exposure of the lower esophagus to acid. Pathological reflux results in symptoms and also esophagitis and ulceration in some patients. Although gastroesophageal reflux disease (GERD) is considered to result from a disorder of motility in the esophagus, gastric acid and peptic activity are deemed pivotal to the initiation and continuation of the esophageal damage and the development of symptoms. Acid exposure in the esophagus is normally less than 4 percent of the 24 hours with a pH below 4. An increase over 4 percent of the time with a pH less than 4 is considered pathological. Hence, antisecretory drugs have become the principle approach to the treatment of reflux symptoms and esophagitis since they reduce the acidity, of gastric juice and the activity of pepsin. Importantly, they also reduce the volume of gastric juice available for reflux into the esophagus. There is a clear relationship between the degree and duration of acid suppression and the relief of heartburn and healing of esophagitis. Pharmacodynamic studies with different dose regimens of the H2-receptor antagonists and the proton pump inhibitors show a difference in the degree and duration of the antisecretory effect, and this correlates closely with the results of clinical trials with respect to the healing of esophagitis and the relief of symptoms. Proton pump inhibitors achieve healing rates by week four, which are not achieved by H2-receptor antagonists even after 12 weeks of treatment. The advantage of proton pump inhibitors over H2-receptor antagonists is due to the greater degree, longer duration of effect and more complete inhibition of acid secretion that maintains intragastric pH above 4 for a maximal duration. Although there is no significant difference between proton pump inhibitors with respect to healing of esophagitis, symptom relief occurs earlier with lansoprazole than omeprazole, and this is probably due to the greater oral bioavailability and faster onset of action of lansoprazole when compared to omeprazole.

2-Pyridinylmethylsulfinylbenzimidazoles↗

Progress with proton pump inhibition.

The proton pump, a H+/K(+)-ATPase located on the secretory canalicular membrane of the parietal cell, forms the final pathway for gastric acid secretion. Omeprazole is concentrated in the secretory canaliculus, where it is converted to its active form, which binds covalently with the H+/K(+)-ATPase, thus inhibiting acid secretion arising from any stimulus. Meta-analysis has defined the primary determinants for peptic ulcer healing as the degree of acid suppression, the duration of suppression over 24 hours, and the length of treatment. The longer duration of acid suppression with omeprazole, particularly during the day, when food is ingested and H2-receptor antagonists are less effective, is reflected in the clinical superiority for symptom relief and ulcer healing and especially for the treatment of erosive esophagitis. Extensive clinical experience has proved omeprazole to be safe, and concerns over hypergastrinemia, ECL-cell hyperplasia, and carcinoid formation have not been substantiated in humans. Recent evidence has shown that omeprazole suppresses Helicobacter pylori and, in combination with antibiotics, can eradicate this organism in a substantial proportion of patients. This effect may result from enhancement of antibiotic bioavailability and optimizing host defense mechanisms.

Duodenal Ulcer↗