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Biomedical subjects

K Bowes

Publications and source records attributed to K Bowes.

6 recordsLinked to original sources
PubMed1994

A dose-ranging study of ranitidine and its effect on intragastric and intra-oesophageal acidity in subjects with gastro-oesophageal reflux disease.

METHODS: This randomized, double-blind, single-centre, crossover study was designed to assess the effects of three regimens of ranitidine (150 mg b.d., 300 mg b.d. and 300 mg q.d.s.) and placebo on intra-oesophageal and intragastric pH in subjects with gastro-oesophageal reflux disease (GERD). Twenty-six subjects were screened, and 9 were evaluable by the admission criteria. These 9 subjects received each of the regimens for 72 h, and a wash-out period of at least 48 h followed each dosing period. Standard meals and beverages were provided. RESULTS: With increasing doses of ranitidine, 24-h intragastric mean H+ and integrated H+ fell, and the percentage of the time the pH was equal to or greater than 4 (% time pH > or = 4) rose: the minimum effective dose for these effects was ranitidine 300 mg daily. With increasing doses of ranitidine there was also a progressive decline in mean 24-h intra-oesophageal H+ and integrated H+, and increasing % time pH > or = 4. The minimal effective dose was 300 mg daily for intra-oesophageal mean H+ and integrated H+, and 600 mg for % time pH > or = 4. The minimal effective dose to decrease the number of reflex episodes was 1200 mg ranitidine. For the daytime upright position, a dose effect of increasing ranitidine was also seen, with minimal effective ranitidine doses of 300 mg for a decrease in mean H+, and 1200 mg for % time pH > or = 4. CONCLUSION: If these higher doses of ranitidine are confirmed to be more effective than the standard 150 mg b.d. regimen for the treatment of patients with gastro-oesophageal reflux disease, then the mechanism of this action probably relates to the lower exposure of the oesophageal mucosa to acid.

Adult↗
PubMedDate not supplied

Computer model of gastric electrical stimulation.

The aim of the study was to simulate gastric electrical stimulation using a computer model of gastric electrical activity and suggest a possible avenue toward reliable gastric pacing. Modeling was based on the conoidal dipole model of gastric electrical activity described earlier. It was assumed that local, nonpropagated contractions can be produced circumferentially using 4 rings of stimulating electrodes supplied with 2-sec phase-locked bipolar trains of 50 Hz, 15 V (peak to peak) rectangular voltage. Temporal and propagation organizations of gastric electrical activity described in the conoidal dipole model were used to derive the geometry of the stimulating electrodes and the time shifts for phase-locking of the electrical stimuli applied to the different circumferential electrode sets. The major assumptions and findings of the model were tested on two unconscious dogs. The model produced completely controllable simulated gastric contractions that could be propagated distally by phase-locking the stimulating voltage. The values of interelectrode distances in different rings, as well as the distances between the successive rings, were also derived. The concept of invoked circumferential contractions that are artificially propagated by phase-locking the stimulating voltage could be an avenue toward reliable gastric pacing of gastroparetic patients.

Animals↗