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Biomedical subjects

A M Sawyerr

Publications and source records attributed to A M Sawyerr.

30 records · Page 2Linked to original sources
PubMed1991

Tolerance during 5 months of dosing with ranitidine, 150 mg nightly: a placebo-controlled, double-blind study.

Repeated dosing with an H2-receptor antagonist results in a modest decrease in antisecretory potency termed "tolerance." The object of this prospective study was to determine whether tolerance is a progressive phenomenon or whether it levels off during prolonged dosing with a standard maintenance dose of an H2-antagonist. The effect of continuous dosing with ranitidine, 150 mg nightly, was compared with intermittent dosing (27 days of placebo each month) with active ranitidine, 150 mg nightly, only on the night of each experiment. Simultaneous 24-hour intragastric acidity and plasma gastrin concentration were measured monthly for 5 months in 17 healthy subjects (7 continuous and 10 intermittent dosing). In the intermittent-dosing group, the antisecretory response to ranitidine, 150 mg nightly, was preserved throughout the 141-day trial period; the median nocturnal integrated acidity decreased from 557 mmol.h/L (day 0) to 38 mmol.h/L on day 1 of dosing, and it ranged between 32 and 55 (median, 45) mmol.h/L during days 29-141. In the continuous-dosing group, there was a significant return of nocturnal intragastric acidity on days 29 and 85 compared with day 1 of dosing. The median nocturnal integrated acidity decreased in the continuous-dosing group from 554 mmol.h/L (day 0) to 87 mmol.h/L on the first day of dosing, and it ranged between 145 and 287 (median, 170) mmol.h/L during days 29-141. Either intermittent or continuous dosing with ranitidine was associated with an elevation of plasma gastrin concentration, which remained constant throughout the 5-month study. Tolerance does develop in healthy subjects during the first month of dosing with ranitidine, 150 mg nightly, but it is not a progressive phenomenon, and it is probably not of clinical relevance.

Adult↗
PubMed1991

Twenty-four hour intragastric acidity and plasma gastrin concentration profiles in female and male subjects.

1. Simultaneous 24 h intragastric acidity and plasma gastrin concentration profiles were determined in 35 healthy young women and 96 healthy young men. 2. The females had a consistently lower median hourly intragastric acidity, and a higher median hourly plasma gastrin concentration, throughout the 24 h. 3. The 24 h integrated intragastric acidity was significantly lower in the female group (females, 485 mmol.h.l-1; males, 842 mmol.h.l-1. P less than 0.001). The 24 h integrated plasma gastrin concentration was significantly higher in the female group (females, 407 pmol.h.l-1; males, 185 pmol.h.l-1; P less than 0.001).

Adult↗
PubMed1991

Review article: the pharmacological implications of leucocyte-endothelial cell interactions in Crohn's disease.

The importance of leucocyte-endothelial cell interactions in the inflammatory process is now recognized. In Crohn's disease, we have proposed that these interactions mediate not only the development of the parenchymal cell infiltrate, but also initiate a process (multifocal gastrointestinal infarction) that leads to ischaemic damage to the bowel wall. We review data on the actions of drugs in the treatment of Crohn's disease and, where known, we highlight their effects on leucocyte adhesion to the endothelium. Corticosteroids inhibit adhesion by inhibiting production of interleukin-1, tumour necrosis factor, interferon gamma, leukotrienes and platelet activating factor. Drugs liberating 5-aminosalicylate inhibit leukotriene production. Cyclosporin inhibits T-cell activation, and amplification of the immune response. Inhibition of leucocyte--endothelial cell interactions probably accounts for some of the beneficial effects of these drugs in Crohn's disease.

Adrenal Cortex Hormones↗
PubMed1991

The effect of ranitidine, cimetidine or famotidine on low-dose post-prandial alcohol absorption.

Plasma alcohol concentration following oral ingestion of 0.3 g/kg of alcohol (ethyl alcohol), one hour after an evening meal, was measured in four groups of 12 healthy subjects. Each group had a control study and a repeat study after 7 days dosing with either placebo or an H2-receptor antagonist (300 mg ranitidine nocte, 800 mg cimetidine nocte, or 40 mg famotidine nocte). There was no significant difference between the control and post-dosing studies in the integrated 4-h plasma alcohol concentration, peak plasma alcohol concentration, or time to reach peak alcohol concentration. This study shows that post-prandial alcohol absorption after 0.3 g/kg of alcohol is not affected by ranitidine, cimetidine or famotidine.

Adult↗
PubMed1991

Eradication of Helicobacter pylori abolishes 24-hour hypergastrinaemia: a prospective study in healthy subjects.

In a prospective study, eight young healthy subjects (five with an active H. pylori infection in the antral mucosa) were treated with a course of tripotassium dicitrato bismuthate, amoxycillin and metronidazole. The triple therapy eradicated infection when assessed 20-24 weeks later by antral biopsy (urease, histology, and 13C urea breath test [4 out of 5 subjects]). Twenty-four hour intragastric acidity and plasma gastrin concentration were measured before treatment, and 4-6 weeks and 20-24 weeks post-treatment. Treatment did not affect acidity in either the H. pylori-positive or H. pylori-negative groups, nor did it affect the plasma gastrin profile in the H. pylori-negative group. Eradication of H. pylori infection in five subjects caused a drop of the median integrated 24-hour plasma gastrin concentration from 558 pmol.h/L before treatment to 307 and 289 pmol.h/L at 4-6 and 20-24 weeks post-treatment, respectively. It is concluded that H. pylori infection is associated with 24-hour hypergastrinaemia, and that in apparently healthy subjects normal gastric physiology can be restored by eradication of the infection.

Adult↗
PubMed1991

The effect of GR122311X, a bismuth compound with H2-antagonist activity, on 24-hour intragastric acidity.

GR122311X (ranitidine bismuth citrate Glaxo Group Research Ltd) is a bismuth compound with histamine H2-receptor antagonist activity. The gastric acid antisecretory activity of three oral dosage regimens of GR122311X was compared with placebo and 150 mg ranitidine b.d. The median 24-h integrated intragastric acidity was 38, 26 and 18% of the median placebo value during dosing with GR122311X 196, 391 and 782 mg b.d., respectively. The 24-h acid suppression with GR122311X 391 mg b.d. was not significantly different to that produced by 150 mg ranitidine b.d. (24% of placebo acidity). The median 24-h urinary bismuth excretion increased with rising dosage of GR122311X from 19.2 micrograms with 196 mg b.d., to 36.4 micrograms with 391 mg b.d., to 68.7 micrograms with 782 mg b.d. In conclusion, GR122311X is an effective antisecretory agent with modest systemic bismuth absorption.

Adolescent↗
PubMed1991

Rebound intragastric hyperacidity after abrupt withdrawal of histamine H2 receptor blockade.

In a series of 24 hour studies, intragastric acidity and plasma gastrin concentration were measured simultaneously in 46 healthy subjects before, during, and 24 to 48 hours after abrupt withdrawal of a histamine H2 receptor antagonist regimen. For 34 days subjects were given either cimetidine 800 mg at night (n = 8), ranitidine 150 mg twice daily (n = 10), ranitidine 300 mg at night (n = 12), nizatidine 300 mg at night (n = 8), or famotidine 40 mg at night (n = 8). All subjects responded to H2 blockade by a decrease in 24 hour intragastric acidity. Withdrawal of H2 blockade resulted in a significant rise in median nocturnal integrated intragastric acidity in 42 of 46 subjects (+36%; 95% CI +19, +55%) compared with prestudy values, but this rise was not associated with a significant change in the median integrated plasma gastrin concentration (+1%; 95% CI -12, +13%). A statistically significant rise in nocturnal acidity was observed after all regimens, except after dosing with famotidine. After stopping, median daytime integrated acidity and plasma gastrin concentrations in the whole group were raised, but not significantly: values were +15% (95% CI +4, +34%) and +5% (95% CI -2, +12%), respectively. A statistically significant increase in daytime acidity was observed only after dosing with ranitidine. In conclusion, intragastric hyperacidity occurs in most subjects after abrupt withdrawal of a histamine H2 receptor blocker, but this phenomenon is not associated with hypergastrinaemia.

Adult↗
PubMed1991

Granulomatous vasculitis in Crohn's disease.

This study investigated a possible vascular origin for granulomas in Crohn's disease. Twenty-four consecutive resected specimens of small and large intestinal Crohn's disease were preserved by arterial perfusion-fixation with 10% formol saline, at mean arterial pressure (100 mm Hg). Fifteen specimens contained granulomas on routine examination of H&E-stained sections. These 15 specimens were examined in detail using a range of immunohistochemical staining techniques to identify vascular structures and granulomas. A total of 485 granulomas were found, 85% of which were identified as being directly involved in vascular injury. The majority (77%) of granulomas were deep to the mucosa; they were found most frequently in the submucosa (42%). The techniques used in this study enhanced the recognition of granulomatous vasculitis. The results suggest that the majority of granulomas in Crohn's disease form within walls of blood vessels. Vascular localization of granulomatous inflammation suggests that the intestinal microvasculature contains an early element in the pathogenesis of Crohn's disease.

Crohn Disease↗
PubMed1990

Severe hepatitis caused by cyproterone acetate.

A case of severe acute hepatitis caused by cyproterone acetate in a 71 year old man with prostatic carcinoma is reported with a review of the literature on hepatic reactions to this drug. The association between the use of cyproterone acetate and liver abnormalities is poorly documented. This is the fourth published report of adverse hepatic reaction to cyproterone acetate and it substantiates other evidence that cyproterone acetate is potentially hepatotoxic. Monitoring of liver function tests should be mandatory in patients receiving high doses of cyproterone acetate; the drug should be withdrawn immediately if abnormal liver function tests are found.

Adenocarcinoma↗
PubMed1989

Pathogenesis of Crohn's disease: multifocal gastrointestinal infarction.

In a prospective study, specimens of resected small and large intestine from fifteen patients with Crohn's disease were prepared by heparin-saline vascular perfusion, followed by either resin casting of the mesenteric vascular supply and tissue maceration or glutaraldehyde perfusion-fixation, resin casting, and tissue clearance. The specimens were examined by macrophotography, histopathology, and either scanning or transmission electronmicroscopy. A pathogenetic sequence of events in Crohn's disease was seen--vascular injury, focal arteritis, fibrin deposition, arterial occlusion mainly at the level of the muscularis propria, followed by tissue infarction or neovascularisation. These features were confined to segments of intestine affected by Crohn's disease and did not occur in normal bowel. The findings suggest that Crohn's disease is mediated by multifocal gastrointestinal infarction. This pathogenetic process is compatible with many of the clinical features of Crohn's disease, and its recognition has important implications for the identification of the primary cause of the illness and advances in clinical management.

Cecum↗
PubMed1978

A comparison of the composition and apolipoprotein content of the lipoproteins isolated from human and ferret (Mustela putorius furo L.) serum.

1. The lipoproteins isolated at densities of less than 1.006, 1.006-1.063 and 1.063-1.21 g/ml from human and ferret (Mustela putorius furo L.) serum were compared. 2. Ferret very low density lipoprotein contained proportionately less triglyceride and more phospholipid than human. 3. Ferret low density lipoprotein contained proportionately more triglyceride and less cholesterol than human. 4. High density lipoprotein was the major lipoprotein in ferret serum. 5. The gel electrophoretic patterns of lipoprotein apoproteins and the pattern of apoprotein solubility in tetramethylurea were similar for human and ferret fractions. 6. The ferret may provide a convenient animal for the study of serum lipoprotein structure, function and metabolism.

Animals↗