SUMMARY Bile acid loss (mg/M2 24h) in the stools of 43 cystic fibrosis (CF) children with pancreatic insufficiency was 751 1 + 48-3, while that of six without clinical evidence of pancreatic disease (133.4 15 9) did not differ from values in 25 controls (109.8 ± 9.8). There was a good correlation between the degree of bile acid (BA) and fat sequestration. Concomitant changes in bile acid and fat loss were observed in one group of six patients studied on and off pancreatic enzymes as well as in a second group of seven children treated with pancreatic supplements and maintained on a normal diet followed by a low fat diet supplemented with medium chain triglycerides. Administration of NA bicarbonate led to a significant decrease in fat loss (15-8 ± 2-7 -* 103 1 9) without any simultaneous change in bile acid excretion (533-1 ± 58-3 --500 4 ± 58 6). Qualitative bile acid patterns in controls, in infants after an ileal resection, and in patients with CF or with coeliac disease showed that the percentage of primary BA followed closely the total amount excreted except in situations where antibiotics were administered. The exact mechanism for the increased loss of BA in CF is unknown. It is found in all age groups and is related to the presence and degree of pancreatic insufficiency. The possibility that unhydrolysed triglycerides may interfere with the intestinal absorption of bile acid needs further confirmation.
Because of the increased incidence of gallstones in cystic fibrosis we compared biliary lipid composition in 26 patients with cystic fibrosis, seven children with cholelithiasis but no cystic-fibrosis and 13 controls. Eighteen of the cystic fibrosis group had cholecystograms, and only one had gallstones. In 14 patients with cystic fibrosis who had stopped taking pancreatic enzymes for one week molar percentage of lipid composition accounted for by cholesterol (mean +/- S.E., 16.3 +/- 2.9) and saturation index (2.0 +/- 0.3) were comparable to values of the cholelithiasis group and higher (P less than 0.01) than those of controls. In 12 patients with cystic fibrosis taking pancreatic enzymes, molar percentage of cholesterol (8.6 +/- 1.7) and saturation index (1.0 +/- 0.1) did not differ from those of controls; in cystic fibrosis there was a preponderance of cholic over chenodeoxycholic acid both off (1.7 +/- 0.2) and on (1.9 +/- 0.3) therapy as compared to the cholelithiasis (0.7 +/- 0.1) and control (0.8 +/- 0.0) groups. The glycine/taurine ratio of conjugated bile acids were lower in enzyme-treated patients with cystic fibrosis (3.7 +/- 0.6) than in patients off treatment (6.4 +/- 1.0), but was higher (P less than 0.01) than in controls (1.8 +/- 0.2). Bile is lithogenic in untreated cystic fibrosis and responds to pancreatic enzymes.
SummaryTo identify gastric factors likely to contribute to fat maldigestion and malabsorption in cystic fibrosis (CF), gastric emptying time, secretion rate, and preduodenal lipolytic activity were studied. Gastric emptying of a liquid test meal and gastric acid secretion were determined in five CF teenagers with pancreatic insufficiency and in five healthy controls. During the first hr, the rate of gastric emptying exhibited a linear pattern in both CF patients and controls. Neither the emptying time nor the gastric secretion rate was different. Lingual lipase activity was measured in eight other CF patients with pancreatic insufficiency and in eight controls.Lipase activity was higher (P < 0.05) in CF patients than in controls with values (X * S.E.) of 34.48 * 11.59 and 12.65 + 5.60 pmole butyric acid min-' ml-I, respectively. No correlation with age or body surface was observed. Intragastric lipolysis of a butterfat triglyceride test meal was fast in both groups, but more extensive (P < 0.05) in CF patients than in controls. The data show that in CF with pancreatic insufficiency, gastric factors contributing to the first step of fat digestion are preserved. In fact, lingual lipase activity was found to be increased, and a more complete intragastric lipolysis was documented. SpeculationIn view of the normal gastric emptying time, high lingual lipase activity, and significant degree of hydrolysis of a fatty meal taking place in the stomach of CF patients, the use of acid-resistant lingual lipase supplements could be considered as a new approach to the treatment of the lipolytic phase defect associated with pancreatic insufficiency in cystic fibrosis.
In vivo studies were carried out in young Sprague-Dawley rats to examine the role of gastric lipolysis on fat absorption and bile acid metabolism. When fed by gastric perfusion 5 times (corn oil, 4 g/day) their usual dietary intake of fat, rats deprived of lingual lipase by the creation of an esophageal fistula had a significant degree of fat and bile acid malabsorption as well as a shortened bile acid half-life when compared to animals with a gastrostomy. The % fat absorption, bile acid loss and bile acid pool were normal in 2 groups of esophageal fistula rats fed the same quantity of corn oil or twice (8 g/day) that amount as a fine emulsion. In view of a negligible gastric lipase activity in animals with an esophageal fistula and of decreased hydrolysis of a triglyceride test meal, these data suggest that gastric lipolysis is of physiological importance in situations where lipolytic mechanisms are stressed by a large fat intkae. Its principal role is to potentiate intestinal lipolysis by facilitating the emulsification of dietary lipids through its formed products and, therefore, the contact of pancreatic lipase with its substrates.
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