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Biomedical subjects

R C Heading

Publications and source records attributed to R C Heading.

At least 127 records · Page 7Linked to original sources
PubMed1978

Techniques and errors in scintigraphic measurements of gastric emptying.

For the monitoring of gastric emptying, a gamma camera or scanner operating from one side of the patient is subject to variations of counting efficiency due to the changing depth of radioactivity. A double-headed scanner was used to investigate the effects of such changes. Tc-99m and In-113m were used as labels for the solid and liquid components of a meal. It was found that the depth of Tc-99m within the stomach decreased by a mean of 13 mm during the first half hour of emptying. Anterior detection alone underestimated emptying rates by an average of 26%. Death changes also introduced errors into "early emptying" measurements made unilaterally. Such artifacts of measurement may compromise mathematical analyses of emptying patterns.

Gastric Emptying↗
PubMed1977

Intestinal absorption of glycine and glycyl-L-proline in the rat.

1. Absorption of [3H]glycine and [14C]-glycyl-L-proline at concentrations between 0-5 and 4 mmol/l was studied by perfusion in vivo of rat jejunal and ileal segments. Absorption was defined as net removal of radioisotope from the perfusate. Radioactivity assays and amino acid analyses were performed on perfusates and on mucosal tissue samples obtained from the perfused segments. 2. At the concentrations studied, absorption rates of glycine and glycylproline were proportional to concentration. Ileal rates were approximately 60% of jejunal rates. Glycylproline absorption was slightly faster than glycine absorption and was associated with the appearance in the perfusate of free glycine and proline in the ratio approximately 3:1. Intraluminal hydrolysis was insufficient to account for the amounts of free amino acids found and glycylproline hydrolase activity at the brush border is known to be minimal. 3. Glycylproline absorption apparently occurred by transport of the intact peptide followed by its intracellular hydrolysis. However, more than one-third of absorbed glycine and one-eighth of absorbed proline returned to the lumen as free amino acid. This reflux of glycine and proline was not proportional to their concentrations in the mucosa.

Animals↗
PubMed1977

Gastric emptying in diabetic autonomic neuropathy.

Gastric emptying was studied in 12 diabetic patients, six with and six without objective evidence of autonomic neuropathy and in 20 non-diabetic controls, using a double isotope scinti-scanning technique which differentiated between solid and liquid emptying. Three patients with autonomic neuropathy exhibited gastric stasis, although this was detected by conventional radiology in only one. Neither the patients with stasis nor those without exhibited abnormally rapid early gastric emptying. In patients without stasis, the normal differentiation between solid and liquid emptying was impaired, suggesting an abnormality of antral peristalsis not attributable to vagal denervation. Both intravenous and oral metoclopramide produced symptomatic improvement in two patients with gastric stasis and restored their gastric emptying to normal.

Adult↗
PubMed1976

Persistent gastrointestinal bleeding due to angiodysplasia of the gut in von Willebrand's disease.

Gastronintestinal vascular dysplasia as a cause of persistently recurring melaena is reported in two patients with von Willebrand's disease. Colonic wall vasculature was affected in one patient, the abnormality being demonstrated both radiologically and at operative hemicolectomy undertaken to control bleeding. Abnormalities in the vasculature of the duodenal and jejunal walls were found in the second patient at operation and necropsy, though not demonstrated by angiography.

Adult↗
PubMed1976

Clinical response of dermatitis herpetiformis skin lesions to a gluten-free diet.

Patients with dermatitis herpetiformis have been studied prospectively for 2 years to assess the effect of a gluten-free diet (GFD) on control of the skin lesions. Daily requirements for oral medication with sulphapyridine or dapsone were reduced by GFD treatment and if complete clinical remission of the skin disease occurred, it was maintained while the diet was strictly observed. However, complete remission did not occur significantly more often in GFD-treated patients than in patients taking a normal diet. Many of the latter group exhibited variation in their drug dose requirements during the period of study. GFD treatment seems desirable for the majority of patients with dermatitis herpetiformis, not only to correct the intestinal abnormality but also to minimize the dose of drugs necessary to control the skin lesions.

Adolescent↗
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↗
PubMed1976

A new radioisotopic technic for the measurement of gastric emptying time of solid meal.

The suitability of a radiopharmaceutical for measuring gastric emptying time of solid meal is described. The gastric emptying T1/2 value of solid meal in normal individuals has been established. Both animal and human experiments indicate 99mTc-DTPA to be an ideal nonabsorbable marker for determing gastric emptying rate and for other gastrointestinal studies as well. Studies are now underway to determine gastric emptying time in patients with gastrectomy and gastrojejunostomy, vagotomy, pyloroplasty, etc.

Adult↗
PubMed1976

Gastric emptying rate measurement in man. A double isotope scanning technique for simultaneous study of liquid and solid components of a meal.

A sequential scintiscanning method was used to study gastric emptying in a total of 46 patients given a meal of cornflakes, sugar and milk containing radioactive markers of the solid and liquid components. In control and duodenal ulcer patients, liquid emptying was faster than solid emptying and could be represented as a monoexponential process, but solid emptying followed a different pattern, better represented as linear emptying with time. However, in patients who had undergone Billroth II gastrectomy there was no evidence of differential emptying of the two markers. In addition, rapid emptying of both markers occurred in the gastrectomy patients during the first 10 min after meal ingestion but did not occur in control or duodenal ulcer patients. The observations illustrate the limitations of using liquid meals to identify the effects of gastric surgery on emptying. Measurements of early emptying and of solid-liquid differentiation are necessary for full definition of gastric emptying after ingestion of a mixed solid and liquid meal.

Animals↗
PubMed1975

Measurement of gastric emptying time--a comparative study between nonisotopic aspiration method and new radioisotopic technique.

A comparative study between modified conventional saline load test and the more recently introduced radioisotopic method was run in 8 normal volunteers. Each subject underwent at least three studies by each of the two methods: (1) aspiration method of Goldstein and Boyle incorporating our modification, and (2) an isotopic method employing a gamma camera with a computer. A liquid meal of isotonic saline was used with or without (997) MTc-DTPA. The results indicated that the gastric emptying T 1/2 (8.8 +/- 3.5 min) obtained by saline load test was shorter than that obtained by isotopic method (12 +/- 3 min). This discrepancy was most likely due to inherent error (incomplete aspiration of the gastric fluid) in the former method giving rise to a false faster emptying time. Moreover, the variations in T 1/2 value in the same individual was much more in the aspiration method than it was in the isotopic method.

Adult↗
PubMed1975

Inhibition of gastric emptying and drug absorption by narcotic analgesics.

The effect of intramuscular pethidine or diamorphine on gastric emptying and the absorption of orally administered paracetamol was assessed in eight normal subjects. 2 Both drugs produced a significant and striking delay in gastric emptying and absorption of paracetamol. 3 It seems inevitable that pethidine and diamorphine will retard the absorption of other orally administered drugs.

Acetaminophen↗
PubMed1975

The fate of four 75Se-labeled amino acids: studies of some unsuccessful pancreas-scanning agents.

The Radiochemical Centre developed a number of alpha-amino acids labeled with 75Se in the hope of finding a pancreas-scanning agent superior to L-selenomethionine. Six were submitted for clinical trial and we tested four of these: D-selenomethionine and three derivatives of selenocysteine. Dynamic scintillation camera studies showed that liver uptake was substantial in all cases but that the time course of accumulation and removal differed between agents. Plasma radioactivity curves demonstrated differences in initial removal rates. Two of the agents showed evidence of incorporation of activity into protein and release into the circulation just as with L-selenomethionine. Whole-body counter measurements showed that the retention of activity from the agents exhibiting early plasma protein incorporation was similar to that of L-selenomethionine. Much of the activity from the other two agents was excreted faster but small proportion was retained for a long time. Although the cummulated activity and absorbed dose were substantially less for at least two of the agents than for 75Se-L-selenomethionine, the lack of sufficient pancreatic concentration renders them inferior as scanning agents.

Amino Acids↗
PubMed1974

Effect of histamine H2-receptor blockade on vagally induced gastric secretion in man.

Metiamide, an antagonist of histamine H(2) receptors, was administered intravenously to normal subjects and to patients with a peptic ulcer during vagal stimulation with a constant infusion of insulin. In normal and peptic-ulcer subjects there were reductions of 70% and 71% respectively in gastric-acid output compared with control tests on the same subjects. The decreased acid output resulted from a reduction in both volume of secretion and acid concentration. Metiamide is therefore a potent inhibitor of vagally-induced gastric acid secretion.

Adult↗