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Biomedical subjects

D C Carter

Publications and source records attributed to D C Carter.

At least 181 records · Page 10Linked to original sources
PubMed1979

Effect of gel fibre on gastric emptying and absorption of glucose and paracetamol.

To determine the part played by altered gastric emptying in the modification of glucose absorption by gel fibres, glucose tolerance tests were done in seven healthy volunteers with and without the addition of pectin to the ingested glucose solution and after pharmacological inhibition of gastric emptying with propantheline. Compared with the controls, pectin significantly reduced blood-glucose. Propantheline had a similar but more pronounced effect. Pectin and guar gum did not substantially alter glucose tolerance in a patient who had had total gastrectomy. In a further investigation, gastric emptying and paracetamol absorption were studied simultaneously in fourteen subjects. In eight of these the study was repeated after addition of guar gum and pectin to the ingested paracetamol. Both gastric emptying and paracetamol absorption were slower after gel fibre but the total absorption of the drug, reflected in urinary recovery, was not significantly reduced. The results suggest that the effects of guar gum and pectin on glucose tolerance and paracetamol absorption could be due simply to alteration in the rate of gastric emptying.

Absorption↗
PubMed1979

Reappraisal of the secretory potency and disappearance rate of pure human minigastrin.

The secretory potency and disappearance rates of pure synthetic human non-sulphated minigastrin (HG-14-I) and pure natural human non-sulphated heptadecapeptide (HG-17-I) were compared in five dogs with gastric fistulas and Heidenhain pouches. Intravenous infusion of equimolar doses of the two gastrins produced equimolar increases over basal of serum immunoreactive gastrin and no statistically significant differences in acid output. Also HG-14-I and HG-17-I did not differ significantly in half-times for disappearance, clearance rates, calculated volumes of distribution, or mean plateau serum levels.

Animals↗
PubMed1978

Effect of dimaprit on gastric acid secretion in conscious cats.

Gastric acid secretion was studied in conscious cats with gastric fistulas. Dimaprit and Nalpha,5-dimethylhistamine produced higher maximal responses than histamine. In the presence of pyrilamine, the maximal response to histamine was equal to that of dimaprit. Pyrilamine increased submaximal but not maximal responses to pentagastrin. Cimetidine decreased the potency of dimaprit but did not alter the maximal response. Gastric acid secretion continued for 90 min after infusion of dimaprit was stopped. Possible mechanisms for the enhancement of acid secretion by pyrilamine include: (a) blocking of an inhibitory histamine H1-receptor and (b) inhibition of histamine methyltransferase.

Animals↗
PubMed1978

Methylated analogues of prostaglandin E2 and the gastric mucosal barrier.

15(R)-methyl PGE2 methyl ester (15MPG) and 16,16-dimethyl PGE2 methyl ester (16DMPG) were assessed for their effect on gastric mucosal permeability to Na+ and H+ in dogs prepared by antrectomy and vagally-denervated fundic pouches. 15MPG did not increase mucosal permeability to either ion when given topically (18.75-300 microgram) or parenterally (30 microgram), and did not affect permeability increases induced by topical 5mM sodium taurocholate in acid solution. 16DMPG caused significant increases in net Na+ gain when given topically (18.75-75 microgram) but did not affect net H+ loss from the pouch lumen. Attempts to use higher doses of 16DMPG were abandoned because of bleeding from the pouch, and perforation in one animal. It is conceivable that 16DMPG could cause adverse effects on the gastric mucosal barrier if used to suppress gastric secretion therapeutically. 15MPG does not share this potentially harmful property and remains worthy of further study as an inhibitor of gastric secretion with therapeutic promise.

Animals↗
PubMed1978

Effect of luminal pH on acid secretion from Heidenhain pouches evoked by topical and parenteral stimulants.

1. An apparatus for intragastric titration has been devised and its validity tested. Both when attached to a beaker simulating a pouch and when attached to a pouch whose secretion was suppressed by infusing cimetidine, the apparatus accurately measured added acid when the endpoint setting was between pH 3.0 and 9.0. At pH 2.0 and 1.0 with liver extract and at pH 1.0 with saline, the amount of acid added was markedly underestimated.2. In dogs with vagally denervated pouches, during stimulation by I.V. infusion of histamine or pentagastrin, the rate of acid secretion as measured by intrapouch titration was uninfluenced by changes in luminal pH between 2.0 and 9.0. The apparent decrease in acid secretion at pH 1.0 could be shown to be due entirely to artifact in that no change in acid secretion was found when the gain in mass of acid was simultaneously measured by using a non-absorbable dilution indicator to measure volume gain and titration of samples to pH 7.0 to measure acid concentration.3. During stimulation of acid secretion by solutions of liver extract or of L-histidine instilled into the pouch, the rate of acid secretion was found to increase markedly as pH was increased from 3.0 to 9.0 thus confirming our earlier findings.4. We conclude that while stimulation of acid secretion by topical stimulants is highly dependent on luminal pH, secretion increasing as pH increases, stimulation by parenteral agents such as histamine and pentagastrin is not influenced by luminal pH in the range from pH 1.0 to 9.0.

Animals↗
PubMed1978

Lower oesophageal sphincter response to gastrin--pharmacological or physiological?

The response of the lower oesophageal sphincter (LOS) to intragastric instillation of protein was assessed in 10 healthy volunteers. Sphincter pressures were measured by a rapid pull-through technique and serum gastrin concentrations during each test were determined by radioimmunoassay. Despite stimulation of gastrin release by protein instillation, no significant change in LOS pressure was observed. However, intravenous pentagastrin (0.25 and 0.5 microgram/kg) produced an immediate increase in sphincter pressure, which then returned to the basal level within four minutes. Thus, although pentagastrin is an effective pharmacological stimulant of the sphincter, endogenous gastrin appears not to be a physiological determinant of LOS pressure in man.

Adult↗
PubMed1978

Effect of atropine and vagotomy on pancreatic polypeptide response to a meal in dogs.

In four conscious dogs the pancreatic polypeptide (PP) response to a standard beef-liver meal was measured by specific radioimmunoassay and compared with the response seen after the intravenous injection of 25 or 100 microgram/kg atropine. All three tests were performed twice in each animal and then repeated after truncal vagotomy. The mean prevagotomy postprandial PP increment was 85 +/- 16 pmol/liter in the first 2-h period and 54.5 +/- 13 pmol/liter in the second. After the injection of 25 microgram/kg atropine there was significant reduction in the early response (mean delta PP = 39 +/- 17 pmol/liter, P less than 0.05), but not the late (mean delta PP = 62 +/- 18 pmol/liter). After 100 microgram/kg atropine sulfate, the response was significantly reduced during both periods (mean delta PP = 5.5 +/- 5.2 and 20 +/- 8.8 pmol/liter, respectively, P less than 0.01). Truncal vagotomy significantly (P less than 0.01) reduced the PP response over both time periods (mean delta PP = 6.4 +/- 2.2 and 5.8 +/- 3.8 pmol/liter), and the small residual response was completely abolished by atropine. In five additional dogs an infusion of bethanechol (100 microgram . kg-1.h-1) caused a significant increase (P less than 0.05) in the plasma concentration (mean delta PP = 40.9 +/- 11.8 pmol/liter), which was abolished by pretreatment with atropine (mean delta PP = -2.9 +/- 2.1 pmol/liter). These studies suggest that PP release in response to a meal in the dog is largely under vagal-cholinergic control.

Animals↗
PubMed1977

Quadruple chemotherapy for advanced malignant disease.

The results of treatment of 48 cases of advanced cancer by quadruple chemotherapy are reported. In only 4 patients was an objective remission obtained, although equivocal remissions were observed in 9 patients. This report is at variance with other recent reports. The reasons for the discrepancy are discussed, and while combination chemotherapy may prove more effective if used earlier in the natural history of malignant disease, in this series the technique does not appear to offer any greater chance of remission than chemotherapeutic agents used singly.

Breast Neoplasms↗
PubMed1977

Effect of cimetidine on the human lower oesophageal sphincter.

Lower oesophageal sphincter pressures in healthy volunteers were measured by a rapid pull-through technique during intravenous infusion of the histamine H2-receptor antagonist, cimetidine. No consistent effects on sphincter pressure were observed which are liable to be of clinical importance. Serum gastrin concentrations during cimetidine infusion were measured by radioimmunoassay and showed no significant variation. In a further series of experiments, the response of the lower oesophageal sphincter to intravenous bolus injection of pentagastrin was measured before and during cimetidine infusion. Cimetidine infusion had no significant effect on the sphincter response to pentagastrin.

Adult↗
PubMed1977

Cimetidine and the gastric mucosal barrier.

The histamine H2-receptor antagonist, cimetidine, when given topically or parenterally, did not affect net luminal Na+ gain or net luminal H+ loss in vagally-denervated pouches of antrectomised dogs. Cimetidine did not affect disruption of the mucosal barrier by 5 mmol/l or 20 mmol/l sodium taurocholate.

Animals↗
PubMed1976

Inhibitors of gastric secretion: current progress.

Several new compounds have become available recently which are potent inhibitors of gastric secretion. The therapeutic potential of these inhibitors in the peptic ulcer diathesis is reviewed and it is concluded that the histamine H2-receptor antagonists show most promise at present. The prostaglandins and gastro-intestinal polypeptides are of considerable physiological interest but are unlikely to have clinical importance in the immediate future.

Animals↗
PubMed1976

Effect of histamine H2-receptor blockade on gastric emptying and serum gastrin in man.

The effect of orally administered metiamide, a Histamine H2-receptor antagonist, on the rate of gastric emptying was assessed in 24 uncomplicated duodenal ulcer patients given a standard meal containing indium 113m D.T.P.A. chelate. Metiamide produced significant slowing of gastric emptying when compared with control studies performed on the same patients following oral administration of a placebo. In a further study the effect of metiamide on the serum gastrin response to a protein meal was assessed in seven healthy male volunteers. Paired experiments demonstrated that a significantly greater elevation of serum gastrin occurred after metiamide than after placebo. The delay in gastric emptying produced by metiamide may be mediated by an elevation of the serum gastrin concentration.

Adult↗
PubMed1976

Effect of the histamine H2-receptor antagonist, cimetidine, on gastric secretion and serum gastrin during insulin infusion in Man.

Cimetidine infusion (100 mg h-1) reduced the acid secretory response to insulin infusion (0.03 units Kg-1h-1) when compared to paired control tests in 6 healthy volunteers. There was no significant difference between cimetidine and control tests in terms of pepsin output or serum gastrin concentrations. Cimetidine also reduced the acid secretory response when administered after 90 minutes of insulin had established a secretory response in extended tests in 3 additional volunteers. Cimetidine may have therapeutic potential in the peptic ulcer diathesis.

Adult↗