Solid Test Meal Research Articles

DUODENAL BULB ACIDITY AND THE NATURAL HISTORY OF DUODENAL ULCERATION

Fasting and post-prandial duodenal bulb pH was recorded in 10 subjects with untreated duodenal ulcers (DU), 10 subjects with healed DU, and 15 healthy volunteers. During fasting, pH was less than 4 for a greater percentage of time in healed than in active DU. Ingestion of a solid test meal accentuated this difference: subjects with active DU and controls both showed less bulb acidification than subjects with healed ulcers. Bulb pH was similar in patients with active ulceration and controls. The finding of neutral bulb pH with active ulceration and low bulb pH with healing may explain the typical cycle of spontaneous healing and relapse in duodenal ulcer disease.

Peripheral and central satiety factors in neuropeptide Y-induced feeding in rats.

In the first study, injection of NPY into the hypothalamic paraventricular nucleus (PVN) caused a robust feeding effect that was attenuated by intravenous infusions of glucose, but not fructose. It is suggested that increased blood glucose has a direct central effect on NPY feeding mechanisms. In a second study, and contrary to a previous report, peripheral administration of CCK-8 had a marked satiety effect in NPY-treated rats. Thus, NPY-induced feeding is, at least for a short time, possibly subject to the satiating action of prandially-released CCK. In a final study, NPY was shown to be without effect on gastric emptying of a solid test meal.

Assessment of gastric emptying using gamma scintigraphy.

Gamma scintigraphy was used to measure the gastric emptying rates of three test meals in human volunteers. Emptying rates were determined for solid and liquid materials alone, and for liquid in the presence of solid material. It was shown that the emptying of solids from the stomach was significantly slower than that of liquid, whether liquid alone or liquid in the presence of solid material. It was concluded from these results that, in the case of a solid test meal from which radio-label could be eluted, the free label would empty considerably faster than the remaining solid material. The emptying rate observed scintigraphically would not, therefore, be a true estimate of the solid emptying rate.

Effect of somatostatin analogue (SMS 201-995, sandostatin) on pancreatic secretion in humans

The effect of the long-acting somatostatin analogue SMS 201-995 on exocrine pancreatic function and hormone release was investigated in a double-blind, placebo-controlled study in healthy subjects. SMS 201-995 was administered subcutaneously at a dose of 25 μg twice daily, and all tests were performed 30 minutes after the morning injection. Pancreatic enzyme secretion, gall bladder contraction, and cholecystokinin response after a Lundh meal were completely inhibited by SMS, while pancreatic enzyme secretion elicited by intravenous injection of secretin and pancreozymin was suppressed by 80 percent. The inhibitory effect of SMS on endogenous cholecystokinin release was fully operative on the sixth day of injection treatment, whereas the inhibitory effect on exogenous cholecystokinin injection significantly decreased after SMS administration for seven days, indicating desensitization of the end organ by somatostatin. The release of pancreatic polypeptide by a solid test meal is abolished by administration of 25 μg of SMS, the release of gastric inhibitory polypeptide is nearly completely suppressed, the response of insulin and C-peptide are significantly lowered, and the gastrin response is only slightly reduced.

Simultaneous measurement of gastric emptying, small bowel residence and colonic filling of a solid meal by the use of the gamma camera.

A method for determining the profiles of gastric emptying, small intestinal residence, and colonic filling of a solid test meal, labelled with 250 microCi 99mTechnetium sulphur colloid has been evaluated in nine healthy volunteers and six patients with a disturbance in bowel habit. Mean small bowel transit time was determined by deconvolving the rate of colonic filling with the rate of gastric emptying. In normal subjects, the stomach appeared to empty exponentially with a half time of 1.2 +/- 0.3 hours (mean +/- SD). Food reached the colon by 2.8 +/- 1.5 hours. The mean small bowel transit time was 4.0 +/- 1.4 hours. In most normal subjects, the colon appeared to fill in a linear fashion with approximately 16% food residues entering every hour, and the profile of colonic filling in normal subjects was similar to the profile of ileal emptying observed after feeding a similar radiolabelled solid meal to 14 patients equipped with terminal ileostomies. There was a highly significant correlation between the onset of breath hydrogen excretion and the appearance of radioactivity over the caecum (r = 0.88, p less than 0.01), though in one third of subjects the increase in caecal radioactivity preceded the rise in breath hydrogen concentration by more than 20 minutes. There was also a highly significant correlation between the mean transit time and values for colonic filling but not values for gastric emptying. Patients with irritable bowel syndrome who had diarrhoea tended towards short small bowel transit and early colonic filling, whereas patients who have constipation tended towards long small bowel transit and delayed colonic filling. This method offers a novel means of assessing small bowel transit time, small bowel residence and the profile of colonic filling in man.

Interpretation of the breath hydrogen profile obtained after ingesting a solid meal containing unabsorbable carbohydrate.

The extent to which monitoring breath hydrogen excretion provides information concerning the entry of the residues of a solid test meal into the colon was investigated in 89 normal subjects, and 11 patients with the irritable bowel syndrome. The profile of breath hydrogen concentration showed an early peak, that occurred soon after ingesting the test meal in 89% subjects. This was followed by a later more prolonged rise in breath hydrogen concentration. The early peak occurred well before a radioactive marker, incorporated in the test meal, reached the caecum and the data suggest it was predominantly caused by the emptying of the remnants of the previous meal from the ileum into the colon. This hypothesis was supported by direct measurements of the rate of delivery of ileostomy effluent in 12 subjects with terminal ileostomies. Fermentation of carbohydrate in the mouth may, however, contribute to the initial peak, but this contribution may be avoided by collecting gas samples from the nares. The secondary rise in breath hydrogen excretion was closely correlated with the arrival of the radioactive marker in the caecum (r = 0.91), p less than 0.001), though the time, at which the secondary peak of breath hydrogen excretion occurred was poorly correlated with the time that all the radioactive test meal had entered the colon. When lactulose was infused directly into the colon, as little as 0.5 g produced a discernible hydrogen response, which occurred within two minutes of the infusion. Increasing the rate of colonic infusion of a 50 ml solution of 10% lactulose from 0.02 to 0.15 g/min in five subjects significantly increased the breath hydrogen concentration. At infusion rates below 0.075 g lactulose/minute, the peak breath hydrogen response preceded the end ot the infusion, while at higher rates of infusion, the peak hydrogen response occurred after the end of the infusion. Although these results confirmed that monitoring breath hydrogen concentration usefully signalled the time taken for a meal containing unabsorbed carbohydrate to reach the colon, it did not reliably indicate the time when all of the meal had entered the colon. Finally, the use of the maximum increase in breath hydrogen concentration as an index of the degree of carbohydrate malabsorption assumes uniform rates of entry into the colon.

Does the oral zinc tolerance test measure zinc absorption?

Increases in plasma zinc concentration were compared with radiozinc absorption after oral test doses. Ten healthy, fasting subjects were each given 385 mumol zinc chloride (25 mg Zn) labelled with 0.5 muCi 65ZnCl2 and a non-absorbed marker, 51CrCl3, dissolved in 100 ml of water; another 10 persons were given 354 mumol zinc chloride and 125 g of minced turkey containing 31 mumol zinc also labelled with 65Zn and 51Cr. Measurements were made of plasma zinc concentration at hourly intervals for 5 hours, radiozinc absorption by stool counting of unabsorbed radioactivity 12-36 hours later, and radiozinc retention by whole body counting at 7 days. The mean percentage of radiozinc absorbed and retained in the body from the two test meals was found to be identical (42%). In contrast the increased area under the plasma zinc curve up to 5 hours after the turkey meal, 28 +/- 9 mumol/L (mean +/- SD) was significantly less than that for zinc chloride alone, 47 +/- 15 mumol/L, p less than 0.005. Despite this difference, a good correlation was found between the area under the plasma zinc curve and 65Zn absorption in individual subjects after each meal. The discrepancy between the results of zinc absorption derived from the plasma zinc curve and 65Zn absorption for the liquid and solid test meals was most likely explained by binding of zinc to food and delayed gastric emptying of the solid meal. With a test meal of turkey meat at least this dampened the plasma appearance of zinc but did not affect its overall absorption.

Gastroduodenal motility disturbances in man.

The specialised regions of the stomach include the cardia, fundus, body, antrum and the pylorus. Not only do these regions have specific secretory functions, but also, they have specific motor functions as well. For example, the proximal stomach is most important in regulating emptying of liquids and the distal stomach and pylorus, the emptying of solids. Disorders of gastric emptying can be classified into two major categories: mechanical obstruction due to increased resistance and functional obstruction (gastroparesis) due to pump failure. Gastroparesis is best diagnosed using a solid test meal which is labelled by a gamma-emitting radionuclide. Agents employed to treat gastroparesis include bethanechol, metoclopramide and domperidone. Entero-gastric reflux occurs when there are abnormalities in the duodeno-gastric pressure gradient or the duodeno-gastric resistance mechanism. Excessive entero-gastric reflux may be seen in patients with gastric ulcers, chronic obstructive pulmonary disease, post-cholecystectomy syndrome or post-operative entero-gastric reflux gastritis. The diagnosis of entero-gastric reflux gastritis depends upon typical symptoms and the demonstration of excessive entero-gastric reflux by scintigraphic techniques or the measurement of bile concentrations within the stomach. Medical treatment with bile chelating agents and surface coating agents has been disappointing. Surgical treatment should only be undertaken as a last resort.

GASTRIC EMPTYING IN THE NORMAL DOG A Contrast Radiographic Technique

A total of 22 radiographic studies was made to determine comparative gastric emptying times of two different solid test meals (intact kibble food and ground kibble food mixed with barium sulfate suspension) in four mature (15‐26 months) normal Beagle dogs under controlled conditions. Complete gastric emptying times of the intact kibble and ground kibble meals of a given dose (8 g/kg of dog food plus 5‐7 ml/kg of the contrast agent) ranged from five to ten hours (7.6 ± 1.98 hours with intact kibble meal and 7.0 ± 1.86 hours with ground kibble meal). Feeding a halfdose of ground kibble meal (4 g/kg of dog food plus 3.5 ml/kg of the contrast agent) resulted in complete gastric emptying times of four to six hours (4.7 ± 0.67 hours). Individual dogs had repeatable gastric emptying times although the times varied among different dogs.

Gastric Emptying in Patients With Chronic Renal Failure Receiving Hemodialysis

Patients with renal failure requiring hemodialysis often suffer from nausea and vomiting. Gastric emptying has not been studied in these patients. To determine whether an abnormality of gastric emptying might account for symptoms in these patients, two groups of ten patients each were selected, one group with symptoms of nausea and vomiting and another without symptoms. Autonomic function was assessed in all patients. Fluid and solid gastric emptying rates were quantified utilizing a dual radionuclide technique. Half-emptying times for fluid and solid test meals were not statistically different from previous standards derived using the same methods in a normal population. Patients with chronic renal failure receiving hemodialysis have no demonstrable abnormality in gastric emptying, whether symptomatic or not.

Effect of infusion of nutrient solutions into the ileum on gastrointestinal transit and plasma levels of neurotensin and enteroglucagon

The small bowel transit time of 100 ml of lactulose solution infused at the ligament of Treitz was measured by breath hydrogen excretion in paired studies carried out in 43 healthy volunteers during infusion (1.2 ml/min) of equal volumes (100 ml) of isotonic solutions of either fat emulsion (Intralipid, Prosparol, or Calogen), protein hydrolysate, glucose, or saline into either the jejunum (90 cm from the teeth), ileum (205 cm from the teeth), or colon (350 or 400 cm from the teeth). Ileal infusion of Intralipid or protein hydrolysate resulted in significant delays in small bowel transit time (125 ± 21 min and 71 ± 11 min, respectively) compared with infusion of saline (50 ± 3 min; p < 0.02 and p < 0.05). These delays were not associated with any significant alteration in plasma levels of neurotensin or enteroglucagon. Small bowel transit time was unaffected by infusion of nutrients into the colon or jejunum, although jejunal infusion of Intralipid increased the plasma levels of enteroglucagon and neurotensin (p < 0.01 and p < 0.02, respectively) after the start of lactulose infusion. In a separate series of paired experiments, infusion of Intralipid into the ileum in 5 volunteers significantly delayed the transit of a solid test meal labeled with 25 μCi of 99mTc-sulfur colloid through both the stomach and small intestine. These data support the existence of a mechanism whereby the presence of unabsorbed food in the ileum may enhance absorption by delaying the passage of food through the small intestine.

Gastric, pancreatic, and biliary secretion and the rate of gastric emptying after parietal cell vagotomy

We compared the gastric, pancreatic, and biliary secretory responses to a liquid test meal and the rates of gastric emptying of liquid and solid test meals in six patients at least 1 year after parietal cell vagotomy with eight unoperated subjects, one with duodenal ulcer disease and seven normal control subjects. Parietal cell vagotomy decreased gastric acid secretion to one third of normal, but total trypsin and bile salt secretion during the first 150 postcibal minutes were normal. The liquid test meal emptied from the stomach faster after parietal cell vagotomy, the pattern of emptying being exponential in the vagotomy patients and linear in the normal subjects. The rate of gastric emptying of a liquid meal, although faster than normal, was less precipitous after parietal cell vagotomy than after truncal vagotomy plus drainage or subtotal gastrectomy, and trypsin and bile salt concentrations were not diluted to abnormal levels, as occurs after these other procedures. Furthermore, emptying and dispersion of solid food remained normal after parietal cell vagotomy. These findings probably explain, at least in part, the decreased incidence of postprandial dumping and diarrhea that accompanies parietal cell vagotomy compared with the other popular operations for duodenal ulcer.

Reduced intraluminal bile acid concentrations and fat maldigestion in pancreatic insufficiency: Correction by treatment

Malabsorption of bile acids is known to occur in patients with pancreatic insufficiency particularly when due to cystic fibrosis. Abnormal biliary secretion or intraluminal acidic precipitation of bile acids could contribute to the steatorrhea of pancreatic insufficiency. To measure bile acid outputs and duodenal concentrations of bile salts and lipids simultaneously, we performed intestinal intubation and perfusion studies during feeding of a solid test meal in 6 healthy controls and 8 adult patients with advanced acquired exocrine pancreatic insufficiency. The effects of various treatment regimens were also investigated. Postprandial bile acid secretion was similar in all treatment groups. However, significant (P < 0.05) reductions in micellar concentrations of bile acids and fatty acids were observed in untreated pancreatic insufficiency. These abnormalities were directly related to pH-induced precipitation of bile acids and were corrected only by the addition of cimetidine to standard pancreatin therapy. Thus, in pancreatic insufficiency, treatment with pancreatin plus cimetidine enhances fat digestion and absorption by reducing both acid-peptic inactivation of lipase and acidic precipitation of bile acids.

Fasting and nonfasting blood ethanol concentrations following repeated oral administration of ethanol to one adult male subject.

Whole capillary blood ethanol concentrations following the oral administration of a 30-ml dose of absolute alcohol (0.32 g/kg absolute alcohol) and 45-ml doses of 95% alcohol (0.45 g/kg absolute alcohol) under varying test meal conditions to an adult male volunteer were measured. Ten different test conditions were two fasting (30 ml and 45 ml), three liquid test meals (45 ml), and five solid test meals (45 ml). The terminal concentration-time data were simultaneously fitted to a modification of the integrated form of the Michaelis-Menten equation. The parametersV m andK m of the Michaelis-Menten equation obtained in this fitting were very close to the average values of these parameters following the constant-rate intravenous infusion of ethanol to six adult male volunteers in another study. The area under the concentration-time curves following the liquid and solid food test meals decreased with an increase in the size of the meal. The reduction in area caused by food was the result of two factors: (a) decrease in efficiency of absorption (average 55%) and (b) slowing of the absorption rate coupled with the operation of Michaelis-Menten elimination kinetics (average 45%).

Mean transit time of solid test meals in gastric emptying.

Gastric emptying of a test meal labelled with 99Tcm-sulphur colloid has been studied in 9 healthy volunteers using a gamma-camera with on-line computer. Mean transit time (MTT) was determined by fitting the time-activity histogram to a gamma-variate, and the half-time of emptying (T1/2) was calculated by exponential fitting of the down-slope of the time-activity curve. MTT showed a smaller coefficient of variance than T1/2. This result suggests that MTT may be a more suitable parameter for definition of normal values and for the separation of normal from pathological patterns of emptying.