Comparison of the effects of medium and long chain triglyceride containing liquid meals on gall bladder and small intestinal function in normal man

We investigated the effects of medium (MCT) and long (LCT) chain triglyceride test meals on gall bladder contraction (using ultrasonography) and small intestinal bile acid concentrations and ileal flow rates (using intubation techniques) in normal individuals. Comparing the effects of ingesting medium chain triglyceride and long chain triglyceride meals, the gall bladder volume was reduced by 23.4 +/- 33.6% and 59.0 +/- 17.1% respectively (mean +/- SD, p less than 0.01, n = 13), the jejunal bile acid concentrations increased significantly only after the ingestion of long chain triglyceride (p less than 0.05, n = 5), while the volume of the postprandial jejunal contents was not significantly different (540 +/- 150, 522 +/- 169 ml, medium chain triglyceride vs long chain triglyceride, p = 0.2, n = 5). The postprandial colonic inflow was 48.5 +/- 12.5 and 123.4 +/- 35.2 ml/h (medium chain triglyceride vs long chain triglyceride, p less than 0.01, n = 5). Thus medium chain triglyceride, compared with long chain triglyceride, produces a smaller input of bile acids into the small intestine and a smaller volume of fluid delivered to the colon. These observations may be relevant to the beneficial effects of medium chain triglyceride substitution for long chain triglyceride in the treatment of diarrhoea in patients with small intestinal disease.     

Comparison of Ileal Effluents, Dietary Fibers, and Whole Foods in Predicting the Physiological Importance of Colonic Fermentation

An in vitro fermentation system that simulates the human colon was used in conjunction with the human ileostomy model to determine whether whole foods or dietary fiber isolates from the same foods could be used in lieu of ileal effluent to estimate the daily colonic production of short chain fatty acids (SCFA). A basal diet and a test food were fed for 3 days to a healthy ileostomate, and the ileal effluent was collected. Dietary fiber intake significantly increased ileal dry matter, ash, protein, and available carbohydrate (total carbohydrate minus dietary fiber) (p less than 0.05). Basal diet, test foods, ileal effluents, and dietary fiber isolates then were fermented in vitro with mixed human fecal microflora for 24 h, and SCFA production (mmol SCFA/g organic matter) was measured. SCFA production from ileal effluent significantly correlated with that from dietary fiber isolates (r = 0.86, p less than 0.05), but not with that from whole foods. Therefore, dietary fiber isolates, rather than whole foods, can provide the closest estimates of colonic SCFA production when ileostomates are not available. Test foods significantly changed molar ratios of individual SCFA within the ileal effluent and dietary fiber isolate groupings (p less than 0.05). In view of the different ileal loads arriving in the colon, we conclude that large differences in SCFA production probably depend on the food consumed.     

Digestibility of Carbohydrate Foods in an Ileostomate: Relationship to Dietary Fiber, in Vitro Digestibility, and Glycemic Response

The aim of this study was to assess differences between starchy foods in the amount of carbohydrate which escapes small intestinal absorption. One ileostomate volunteer tested in metabolic feeding trials a total of 20 starchy foods (nine of which were repeated on two to seven occasions, mean 3.5 +/- 1.7). This ileostomate volunteer exhibited macronutrient and fiber losses that were within 97.3 +/- 6.6% of the mean, for a range of foods eaten by three other ileostomates and was therefore believed to be representative. Measurement of available carbohydrate in ileal effluent demonstrated a wide range of recoveries from 2.7 to 18% from different starchy foods. The available carbohydrate losses related to the fiber content (r = 0.885, p less than 0.001), in vitro digestibility of the food (r = -0.867, p less than 0.01), and their glycemic responses (r = -0.611, p less than 0.05). Our data support the concept that available carbohydrate losses to the colon may be greater in many foods than the carbohydrate entering the colon as dietary fiber. The food factors responsible are diverse and the possible metabolic consequences of carbohydrate malabsorption may be broad.     

Microbial flora and bile acid metabolism in patients with an ileal reservoir

Bacterial flora of ileum effluent and bile acid metabolism were investigated in 11 patients 11-44 months after construction of a Kock's continent ileostomy. Bacteriologic investigation showed significantly more microorganisms per millilitre (p less than 0.01) and a more colon-like flora--that is, anaerobic microorganisms (p less than 0.001)--in ileum effluent of continent ileostomy patients than in ileum effluent of patients with a conventional ileostomy. The reabsorptive capacity of the reservoir mucosa was tested by direct introduction of a radioactively labelled conjugated bile acid, 23-75Se-25-homotaurocholic acid (SeHCAT), into the ileal pouch. After 4 h, 90% of the SeHCAT activity had been reabsorbed from the reservoir. Quantitative and differential analysis of bile acids in the ileum effluent showed unconjugated and predominantly primary (88%) bile acids, suggesting a minimal influence of bacterial flora on bile acid metabolism. Moreover, total bile acid loss appeared to be within normal limits.     

Comparison between the bacterial and oligosaccharide content of ileostomy effluent in subjects taking diets rich in refined or unrefined carbohydrate.

Dietary surveys have shown that patients with Crohn's disease tend to eat more sucrose than control subjects and this investigation was undertaken to determine whether a diet rich in refined carbohydrate affects the bacterial flora of the terminal ileum. Ileostomy effluent in five patients with Crohn's disease and five with ulcerative colitis after two weeks on a diet rich in sucrose and refined cereal has been compared with the same period on a diet low in sucrose and rich in unrefined cereal. Observations were made hourly for nine hours after equicaloric breakfasts representing the two diets. The amount of ileostomy effluent was greater on the unrefined carbohydrate diet both in terms of wet weight (238 +/- 89 g vs 162 +/- 79 g, p less than 0.02) and dry weight (23 X 6 +/- 6.8 g vs 14.9 +/- 6.6 g, p less than 0.01); surprisingly, the amount of glucose and oligosaccharide was also greater (169 +/- 41 mg vs 82 +/- 26 mg, p less than 0.001) in all 10 volunteers. The bacteriological flora per gram was also higher on the unrefined carbohydrate diet after the test meal (p less than 0.02 between three and six hours) as a result of a general increase in all organisms. The relative proportions of the organisms did not vary between the two diets. No differences were detected between patients with ulcerative colitis and those with Crohn's disease.     

Postprandial lipoprotein metabolism in normal and obese subjects: comparison after the vitamin A fat-loading test

Abnormalities in fasting lipid and lipoprotein levels are known to occur in obesity and other hyperinsulinemic states. However, postprandial lipoprotein metabolism has not been studied systematically in obese subjects using sensitive techniques to distinguish between triglyceride-rich lipoprotein particles derived from the intestine and the liver. In the present study the vitamin A fat-loading test was used to label intestinally derived triglyceride-rich lipoprotein particles in the postprandial state. Lipid parameters in seven normolipidemic obese subjects [body mass index, 43.7 +/- 2.81 kg/m2 (mean +/- SEM)] were compared to those in eight matched normal weight controls (body mass index, 23.6 +/- 0.72 kg/m2) during the 24-h period following ingestion of a mixed meal with a high fat content to which vitamin A had been added. Although subjects were selected for normal fasting lipid levels, in the obese group fasting triglycerides were significantly higher (1.35 +/- 0.12 vs. 0.68 +/- 0.08 mmol/L; P less than 0.0005) and high density lipoprotein (HDL) cholesterol was lower (0.94 +/- 0.08 vs. 1.35 +/- 0.11 mmol/L; P less than 0.01). The obese subjects had a greater postprandial triglyceride response to the test meal (P less than 0.05). The cumulative increment in total plasma triglycerides was 3.35-fold greater in obese than control subjects, while that of retinyl ester was only 1.63-fold greater, suggesting that a significant portion of the postprandial triglyceride response is due to endogenous hepatic lipoproteins. Postprandial plasma triglyceride and retinyl ester increment correlated with basal triglycerides (r = 0.72; P less than 0.005 and r = 0.57; P less than 0.03, respectively) and negatively with fasting HDL (r = -0.51; P less than 0.05 and r = -0.60; P less than 0.02, respectively). In the obese, the HDL triglyceride content increased maximally 4 h postprandially (4.1% to 6.1%; P less than 0.005) and phospholipid at 12 h (25.8% to 28.7%; P less than 0.05), with lower cholesteryl ester (21.1% to 17.5%; P less than 0.002) at 8 h, reflecting exchange of surface and core lipids with triglyceride-rich particles after the meal. In obese and control subjects the magnitude of HDL triglyceride enrichment after the meal correlated positively with the postprandial triglyceride increment (r = 0.74; P less than 0.007) and negatively with the fasting HDL cholesterol concentration (r = -0.80; P = 0.002). We conclude that even normolipidemic obese subjects have greater postprandial lipemia and triglyceride enrichment of HDL after ingestion of a high fat meal.(ABSTRACT TRUNCATED AT 400 WORDS)     

Ileal excretion and bacterial modification of bile acids and cholesterol in patients with continent ileostomy.

Bile acid (acidic sterol) and neutral steroid excretion were determined in 15 patients, five with conventional ileostomy, five with continent ileostomy, and five with continent ileostomy and an ileal resection. Acidic sterol losses were normal in conventional ileostomy patients and not significantly increased in those with continent ileostomy alone. Bile acid excretion rates were significantly increased in patients with a continent ileostomy and an ileal resection. Neutral steroid excretion was similar in all groups and not different from normal. Deoxycholic acid was not detected in ileal effluent of patients with conventional ileostomy and less than 2% of neutral steroid excreted was in the form of bacterial metabolites of cholesterol. The same was true of six of the 10 patients with continent ileostomies; in the other four patients at least 10% of acidic or neutral steroids were excreted as secondary bile acids or as a coprostanol. Modification of steroids was not related to ileal resection. Continent ileostomy was associated with a significant increase in percentage water content and a reduction in the pH of ileal effluent.     

Impaired endothelial function following a meal rich in used cooking fat

OBJECTIVES: The purpose of this study was to test the hypothesis that intake of used cooking fat is associated with impaired endothelial function. BACKGROUND: Diets containing high levels of lipid oxidation products may accelerate atherogenesis, but the effect on endothelial function is unknown. METHODS: Flow-mediated endothelium-dependent dilation and glyceryl trinitrate-induced endothelium-independent dilation of the brachial artery were investigated in 10 men. Subjects had arterial studies before and 4 h after three test meals: 1) a meal (fat 64.4 g) rich in cooking fat that had been used for deep frying in a fast food restaurant; 2) the same meal (fat 64.4 g) rich in unused cooking fat, and 3) a corresponding low fat meal (fat 18.4 g) without added fat. RESULTS: Endothelium-dependent dilation decreased between fasting and postprandial studies after the used fat meal (5.9 +/- 2.3% vs. 0.8 +/- 2.2%, p = 0.0003), but there was no significant change after the unused fat meal (5.3 +/- 2.1% vs. 6.0 +/- 2.5%) or low fat meal (5.3 +/- 2.3% vs. 5.4 +/- 3.3%). There was no significant difference in endothelium-independent dilation after any of the meals. Plasma free fatty acid concentration did not change significantly during any of the meals. The level of postprandial hypertriglyceridemia was not associated with change in endothelial function. CONCLUSIONS: Ingestion of a meal rich in fat previously used for deep frying in a commercial fast food restaurant resulted in impaired arterial endothelial function. These findings suggest that intake of degradation products of heated fat contribute to endothelial dysfunction.     

Emptying of the terminal ileum in intact humans. Influence of meal residue and ileal motility

Emptying of the terminal ileum was assessed in 15 healthy humans by injecting technetium 99m-diethyltriaminopentaacetic acid into the bowel through a multilumen orocolonic tube. The subsequent arrival of isotope in the colon was quantified by gamma-scintigraphy and colonic filling curves were obtained. Studies were performed during fasting (n = 5) cnd 2.5 h after either a low residue meal (n = 5) or a meal made high in residue (n = 5) by adding 4 g of guar. The time for 50% of the isotope to reach the colon (T50) was significantly accelerated after both meals, being 72 +/- 15 min for the high residue meal and 62 +/- 8 min for the low residue meal, compared with 183 +/- 37 min (p less than 0.01) in the 5 fasting subjects. Although the addition of guar did not alter T50 significantly, it did cause a significant fall in the rate of colonic filling, implying increased isotope dilution. Delay at the ileocolonic junction, as shown by plateaus in the middle of the colonic filling curves, was uncommon. Hold-up was significant in only 2 of 10 postprandial and 2 of 5 fasting studies. Rates of ileocolonic transit could not be related to either a mean ileal motility index or the occurrence of specific ileal motor patterns immediately proximal to the ileocolonic junction. Fasting ileocolonic transit was characteristically erratic but could not be related to interdigestive migrating motor complexes, which were rarely observed in the last 60 cm of ileum. We conclude that ileocolonic transit in humans is related to the rate at which material accumulates in the ileum, being rapid postprandially (when ileal flow is high) and slow and erratic during fasting. This method yields consistent results and could be used to define further factors that influence ileocolonic inflow.     

Patient evaluation of the conventional ileostomy

A survey of 322 ileostomates was undertaken to assess the impact of an ileostomy and determine problems that are encountered by patients. Most patients (72 percent) felt they led normal lives with the ileostomy and encountered fewer restrictions in life-style than with their disease. However, only 35 percent of patients felt their ileostomies functioned perfectly. Skin irritation (49 percent), offensive noise and odor (42 percent), detection of the appliance (17 percent), and difficulty in handling the appliance (29 percent) were some of the problems encountered. Psychologic problems were related to poor body image (22 percent) and sterility or impotence (12 percent). All of these problems, however, were less than had been anticipated. Various sources of information were available to the ileostomate. However, about 50 percent of patients felt they received inadeoquate preoperative information or counseling.     

Effect of Specific Foods, Beverages, and Spices on Amount of Ileostomy Output in Human Subjects

To measure the effect of various selected foods on the amount of ileal excreta, 37 metabolic balance studies were performed on seven subjects who had normal functioning ileostomies for ulcerative colitis. Although this investigation was conducted with the subjects living at home and selecting their own diet, metabolic balance techniques were carefully observed. The diet was identical in the 3-day control and 3-day experimental period except for the alteration of one aspect of the diet in the experimental period. The substances tested were those often either interdicted for or avoided by ileostomates. Only seven (five fruits, one vegetable, and prune juice) of the 37 dietary substances significantly increased the ileal effluent. Excessive water intake, alcohol beverages, fried foods, and spices did not increase ileostomy output. A small but significant loss of sodium and in some instances potassium was observed with prune juice and some fruits that statistically increased ileal output. Although a limited number of foods were studied, application of the results suggests that many dietary substances generally avoided by or interdicted for ileostomates did not significantly increase the amount of ileal excreta when objective measurements are made.     

Diurnal serum levels of primary conjugated bile acids : Assessment by specific radioimmunoassays for conjugates of cholic and chenodeoxycholic acid

The serum levels of conjugates of chenodeoxycholic acid (chenyl conjugates) and of cholic acid (cholyl conjugates) were determined by specific radioimmunoassays during a 24-hour period, which included three liquid meals and an overnight fast, in five healthy volunteers, five patients with previous cholecystectomy, five patients with documented bile acid malabsorption because of ileal resection, and four pregnant women. In healthy subjects, fasting-state levels of chenyl conjugates, when compared with those of cholyl conjugates, were higher; postprandially, levels of chenyl conjugates rose to a peak sooner (30 minutes vs 60 minutes) and to higher levels (5.2 +/- 1.3 muM vs 2.0 +/- 0.5 muM, M +/- SE). In cholecystectomised patients, the integrated areas under the curve for both bile acids were similar to those of the healthy controls, but postprandial peaks were less marked. In patients with bile acid malabsorption, postprandial rises of chenyl conjugates were lower but remained relatively constant throughout the day, whereas cholyl conjugate levels diminished progressively with each successive meal, consistant with depletion of the cholyl, but not the chenyl, pool. In three of four pregnant women, the postprandial rise of chenyl conjugates was disproportionately less compared with that of healthy controls. These results confirm the dynamic complexity of serum bile acid levels in man and indicate that the major circulating primary bile acids are chenyl conjugates. They support previous proposals that jejunal absorption of chenyl conjugates is important in the normal enterohepatic circulation of bile acids; and they suggest an abnormality in the enterohepatic circulation in pregnancy.     

Effects of metformin on glucose, insulin and lipid metabolism in patients with mild hypertriglyceridaemia and non-insulin dependent diabetes by glucose tolerance test criteria.

The effect of metformin treatment was studied in nine patients with mild (fasting plasma glucose concentration less than 7.5 mmol.l-1) non-insulin-dependent diabetes mellitus (NIDDM) and fasting plasma triglyceride (TG) concentration greater than 2.0 mmol.l-1. Individuals were studied before and three months after receiving 2.5 g/day of metformin. Mean hourly plasma glucose concentration from 8 AM to 4 PM (7.5 +/- 0.5 vs 6.5 +/- 0.4 mmol.l-1, p less than 0.001), as well as glycosylated hemoglobin levels (7.0 +/- 0.5 vs 6.2 +/- 0.2%, p less than 0.02) were significantly lower following metformin treatment. The improvement in glycaemic control was not associated with an improvement in insulin stimulated glucose disposal as measured by the glucose clamp technique. Mean hourly day-long concentrations of plasma insulin (519 +/- 81 vs 364 +/- 64 pmol.l-1, p less than 0.001), FFA (502 +/- 45 vs 460 +/- 35 mu mol.l-1, p less than 0.01), and triglyceride (3.60 +/- 0.33 vs 3.02 +/- 0.31 mmol.l-1, p less than 0.001) concentrations were significantly lower following three months of metformin treatment. Finally, fasting plasma TG concentration, very low density lipoprotein (VLDL)-TG, and VLDL-cholesterol concentrations were significantly decreased, while high density lipoprotein (HDL)-cholesterol concentration was significantly increased following metformin therapy. Thus, metformin administration to individuals with NIDDM, who did not have significant fasting hyperglycaemia, led to a decrease in plasma glucose, insulin, FFA, and TG concentration, and an increase in plasma HDL-cholesterol concentration.(ABSTRACT TRUNCATED AT 250 WORDS)     

Diagnostic value of serum primary bile acids in detecting bile acid malabsorption.

Serum cholic and chenodeoxycholic acid conjugates were measured in fasting conditions and after meals in 14 patients with bile acid malabsorption due to ileal resection. Mean serum fasting levels of both primary bile acids did not differ from the controls. After meals, serum cholic acid peaks were lower in patients with ileal resection than in control subjects (p less than 0.001), while chenodeoxycholic acid peaks were reduced in colectomised patients (p less than 0.01). In the sera from patients with ileal resection, the glycine/glycine + taurine ratio for cholic and chenodeoxycholic acid increased (p less than 0.001) from morning to evening, and glycine/glycine + taurine ratio for chenodeoxycholic acid was significantly (p less than 0.01) different from the controls in the sera collected in the evening. The results are consistent with the concept of a better intestinal conservation of chenyl, mainly of the glycine conjugated from, than of cholylconjugates, in patients with ileal resection; this is probably because of passive absorption in the intestine. The postprandial peaks of serum cholic acid conjugates may therefore be regarded as a test of ileal dysfunction, while peaks of chenodeoxycholic acid conjugates suggest colonic impairment.     

Short-chain fatty acids in bowel contents after intestinal surgery

Short-chain fatty acids are produced in the human colon by bacterial fermentation of dietary fibers and other saccharides escaping absorption in the small bowel. Short-chain fatty acid concentrations were determined together with production rates in 6- and 24-h incubations of intestinal outputs from 56 patients with various types of intestinal resections. Concentrations and 6- and 24-h production rates in feces from 9 healthy persons (controls; median +/- SD) were 98.9 +/- 21.4 mmol/L and 17.2 +/- 5.1 and 9.3 +/- 1.5 mmol/L.h, respectively. Colectomized patients with short bowel syndrome had extremely low concentrations (0.8 mmol/L) compared with controls (p less than 10-5), patients with ileostomy (p = 0.003), and ileal reservoirs (p less than 10-5), and showed low 6- and 24-h production rates (1.5 and 0.9 mmol/L.h, respectively; p less than 10-5 vs. controls). Short-chain fatty acids in ileostomic digesta (11.1 mmol/L) were decreased (p = 0.011) compared with outputs from ileal reservoirs (51.5 mmol/L), although production rates were in the same order of magnitude--all below control values (p less than 0.001). Patients partially colectomized and patients with small bowel bypass or short bowel syndrome with preserved colon had normal fecal concentrations with decreased production rates of short-chain fatty acids vs. controls (p less than 0.01). Only minor changes in ratios between individual acids were found. Reciprocal values of short-chain fatty acid concentrations correlated to volumes of outputs from both small intestine (r = 0.86, p less than 10-6) and colon (r = 0.79, p less than 10-6) when results were cumulated. It is concluded that partial resections of colon and the small bowel do not influence the fecal concentration level of short-chain fatty acids as long as colon is not totally resected.     

Different glycaemic responses to pasta, bread, and potatoes in diabetic patients

To evaluate whether the same amount of carbohydrate (CHO) in different foods gives different glycaemic responses when consumed in the context of a real meal, seven diabetic patients were given in a random order and on alternate days three test meals of identical composition. Each meal consisted of a fixed part to which a 50 g CHO portion of either bread (90 g) or spaghetti (65 g) or potatoes (285 g) was added. The glycaemic response was significantly higher after ingestion of bread than after the spaghetti meal both at 2 (5.9 +/- 0.8 vs 4.3 +/- 0.7 mmol/l X hour, p less than 0.05) and at 5 hours (16.5 +/- 3.6 vs 9.8 +/- 2.3 mmol/l X hour, p less than 0.05). The glycaemic response to the potato meal was similar to that for bread at 2 hours (6.2 +/- 1.2 mmol/l X hour, p less than 0.05 vs spaghetti) and intermediate between the two other test meals at 5 hours (14.6 +/- 4.3 mmol/l X hour). Meal planning for diabetic patients should be based not only on the biochemical properties but also on the glycaemic response to the food.     

Ileal dysfunction in Crohn's disease assessed by the postprandial serum bile acid response.

We assessed ileal functional integrity in 20 consecutive patients with Crohn's disease by sequential measurement of the postprandial serum bile acid concentration. In all 14 patients with active Crohn's disease involving the terminal ileum, the mean (+/- SEM) peak response in the cholylglycine (0.4 +/- 0.04 mumol/l, n = 14) as well as in the total serum bile acid concentration (2.0 +/- 0.4 mumol/l, n = 10) was similar to that seen in a group of children who had undergone ileal resection. A significantly greater increase in the cholylglycine (1.8 +/- 0.18 mumol/l, n = 16, P less than 0.01) and in the total serum bile acid concentration (9.8 +/- 2.4 mumol/l, n = 11, P less than 0.025) was noted in normal children. In five of the six remaining patients (three with Crohn's disease shown not to involve the ileum and two of three with asymptomatic, treated Crohn's ileitis) and in seven patients with ulcerative colitis, the meal stimulated responses were normal. These preliminary results suggest that measurement of the serum bile concentration after a meal stimulus may provide a valuable index of ileal inflammation in patients with Crohn's disease.     

Ileostomy using an interposed ileal segment to function as a ‘neocolon’

A new type of ileostomy was constructed in rats using an interposed ileal (I-I) segment functioning as a neocolon. The effects of this operation in these rats were compared with a control group undergoing conventional ileostomy (I). Rats in the I group lost weight throughout follow-up, whereas rats in the I-I group regained weight and were significantly heavier four weeks after surgery. Transit time from the stomach to the stoma was significantly prolonged in the I-I group (187 +/- 29 minutes) when compared with the I group (141 +/- 17 minutes, P less than 0.01). Serum analysis revealed no significant differences in total protein, lipids, electrolytes (Na, Cl, CO2), and osmolarity between the groups. Biliary bile salt concentration, normalized bile flow, and normalized bile acid output in the I-I group were not different from those in unoperated control rats, suggesting unimpaired bile acid metabolism. These data suggest this operative procedure has the beneficial effects of slowing intestinal transit and promoting postoperative recovery without impairing distal ileal function.     

Estimation of gastric residence time of the Heidelberg capsule in humans: effect of varying food composition

In animal and human studies, the gastric emptying of large (greater than 1 mm) indigestible solids is due to the activity of the interdigestive migrating myoelectric complex. The gastric residence time (GRT) of an orally administered, nondigestible, pH-sensitive, radiotelemetric device (Heidelberg capsule) was evaluated in three studies in healthy volunteers. In 6 subjects, the GRT of the Heidelberg capsule was compared with the half-emptying time (t1/2) of diethylenetriaminepentaacetic acid labeled with technetium 99m after a 4-ml/kg liquid fatty meal. The mean (+/-SD) GRT (4.3 +/- 1.4 h) was significantly (p less than 0.001) longer than the mean t1/2 (1.1 +/- 0.3 h); the GRT was prolonged compared with the t1/2 in each subject. In a randomized, crossover trial in 10 subjects, frequent feeding caused a dramatic prolongation in mean GRT of the capsule compared with the fasting state (greater than 14.5 vs. 0.5 h, p less than 0.005). In another crossover study in 6 subjects, the GRT of the capsule was evaluated after an overnight fast, a standard breakfast including solid food, and a liquid meal (i.e., 200 ml of diluted light cream). The mean GRT was 2.6 +/- 0.9 h after the liquid meal vs. 1.2 +/- 0.8 h after fasting (p less than 0.025). The mean GRT after the breakfast was 4.8 +/- 1.5 h, which was significantly greater than that after fasting (p less than 0.001) and after the liquid meal (p less than 0.01). These data suggest that the GRT of the Heidelberg capsule is a marker of the interdigestive migrating myoelectric complex in humans, the interdigestive migrating myoelectric complex can be markedly delayed by frequent feedings with solids, and the interdigestive migrating myoelectric complex is delayed by both liquid and solid meals.     

Increased platelet aggregation during alimentary hyperlipemia in normal and hypertriglyceridemic subjects

The influence of 2 different fatty meals, rich in either saturated or polyunsaturated fatty acids, on platelet aggregation in 7 normolipemic subjects and in 10 patients with phenotype IV hyperlipemia, was studied. 3 h after ingestion of a saturated- or polyunsaturated-fat-rich meal, plasma triglycerides were similarly increased in both groups. 5 h after ingestion of fat of either origin, the plasma triglyceride level in normal subjects returned almost to the fasting level, whereas in patients with hypertriglyceridemia it was still elevated. Platelet aggregation induced by ADP in platelet-rich plasma significantly increased in the normal group 3 h after both meals, whereas in the patient group it increased only after the saturated-fat-rich meal. These results were not changed 5 h after the meals. Postprandial elevated platelet activity was not correlated with increased plasma triglyceride concentration. No changes were found in washed-platelet aggregation in normal subjects, whereas the patient-derived washed platelets showed increased aggregation after the saturated-fat-rich meal. Plasma chylomicrons prepared from both groups during alimentary hyperlipemia inhibited ADP-induced platelet aggregation as well as thrombin-induced platelet 14C-serotonin release. This study indicates that the intake of fatty meals induces acute disturbance in platelet aggregation, favoring thrombosis. These changes are more comprehensive in hyperlipemic patients and after a saturated-fat-rich meal.