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Query: UMLS:C0024523 (malabsorption)
 7,319 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The secretion of pregastric esterase and other oral lipases has been detected in 13 species. Research on secretion by the human, calf, kid goat, lamb, and rat of pregastric esterase has been significant. Secretion by calves is little affected by age or diet but is greater when calves are nipple fed than when pail fed. Whole milk sham-fed to calves exhibits immediate, sharp decreases in pH and rennet coagulation time resulting from liberation of free fatty acids by pregastric esterase. Bacterial counts in sham-fed products are higher than in control (nonfed) products, but during subsequent incubation bacterial numbers increase less rapidly in sham-fed products. Calf pregastric esterase is a major fat digestive enzyme in young calves but gradually becomes subsidiary to pancreatic lipase as secretion of the latter develops with age. Calf, kid goat, and lamb pregastric esterase exhibits optimum activity on milk fat but is capable of splitting other dietary fats. Data on oral and "gastric" lipases in calves, humans, and rats suggests that gastric lipase is oral lipase. Data on pH and temperature optima as well as activation and inhibition of oral lipases is contradictory but appears to vary considerably between species. Calf pregastric esterase exhibits a unique specificity for fatty acids 4:0 to 10:0 and preferentially hydrolyzes the primary ester position of glycerin. Preparations of calf, kid goat, and lamb pregastric esterase are used commercially to impar typical flavors to Italian-type and Feta cheeses and to accelerate flavor development in other cheeses and cheese-like products. Butterfat modified by pregastric esterase is utilized to impart dairy flavor character to a wide range of processed foods. Treatment with pregastric esterase of calf scours and human malabsorption of syndrome also has been reported.
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PMID:Pregastric esterase and other oral lipases--a review. 32 89

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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PMID:The role of gastric lipolysis on fat absorption and bile acid metabolism in the rat. 49 66

The structure and function of enterocyte membranes are particularly sensitive to the degree of fatty acid saturation. The objective of the present study was to assess intestinal fat transport in essential fatty acid (EFA)-deficient animal models. Both the digestive and absorptive phases leading to the formation and the secretion of triglyceride (TG)-rich lipoproteins were investigated. After an intraduodenal fat infusion, the percentage increase of plasma TG over fasting values was examined over a period of 4 h in two groups of control and EFA-deficient rats. Lower values at 1 and 2 h (P less than 0.05) were observed in EFA-deficient rats, suggesting fat malabsorption. Likewise, postprandial chylomicronemia was diminished. In a separate group of rats, EFA deficiency was associated with reduced TG and chylomicron-TG transport into lymph. Although pancreatic lipase activity did not change (47.1 vs. 46.2 mumol free fatty acids.mg protein-1.h-1), bile flow was decreased over the 8-h period of collection. Concomitantly, a significant decline (nmol.min-1.g liver-1, P less than 0.05) was discernible in the biliary secretory rate of bile salts (14.09 +/- 2.13 vs. 35.09 +/- 3.73), phospholipids (7.01 +/- 0.61 vs. 11.79 +/- 1.65) and cholesterol (0.19 +/- 0.01 vs. 0.83 +/- 0.06). In vitro studies, utilizing everted sacs incubated with mixed micelles, revealed that EFA-deficient jejunal segments of rats incorporated and esterified less [14C]oleic acid (21 and 32%, respectively). Moreover, the synthesis and secretion of TG-rich lipoproteins were found markedly reduced in mouse jejunal explant cultures. We conclude that EFA deficiency modifies both the intraluminal and intracellular phases of fat absorption.
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PMID:Intraluminal and intracellular phases of fat absorption are impaired in essential fatty acid deficiency. 153 63

Infection with Giardia lamblia often causes only minor mucosal changes to the small intestine yet frank fat malabsorption may still occur. Some evidence suggests abnormal pancreatic exocrine function in subjects with giardiasis although the mechanism and significance of this is unclear. Studies were conducted in vitro to determine the effect of G. lamblia trophozoites or culture filtrates from the organism on lipolysis of triglyceride by porcine pancreatic lipase. Live trophozoites significantly inhibited lipolysis. The degree of inhibition increased with longer duration of lipase exposure to trophozoites. Total amounts of enzyme inhibited were proportional to enzyme concentration, while the percentage inhibition was greatest at lowest concentration. At a lipase concentration of 1.7 i.u./ml, enzyme activity was reduced by 89.7% compared to controls after incubation for 4 h with trophozoites. The effect was abolished using killed, intact trophozoites. Culture filtrates of G. lamblia did not inhibit lipolysis. Specificity of the effect was suggested by the failure of another flagellate protozoan, Trichomonas vaginalis, to inhibit lipase. In this assay system the inhibition of lipolysis was not dependent on the bile salt concentration present. The impact of this effect in vivo remains to be determined but it may contribute to fat malabsorption in giardiasis.
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PMID:The effect of Giardia lamblia trophozoites on lipolysis in vitro. 194 23

The pancreas has an enormous reserve capacity, and significant malabsorption usually signals complete absence of exocrine function. However, there is evidence that acid lipases of nonpancreatic origin play an important compensatory role. Complete duodenal hydrolysis of fat requires a series of complex interdependent physicochemical events involving pancreatic lipase, colipase, phospholipase A2, and bile salts in an environment where the pH must be close to neutrality. Lipolytic products must then be shuttled through the unstirred water layer to the surface of the microvillus membrane by ionized bile salts, which must be present in sufficient concentrations to form micelles. In pancreatic insufficiency, there is not only a defective lipolytic phase but also an impaired micellar phase. The output of bile salts is decreased because of increased fecal loss. Furthermore, a significant percentage of bile salts precipitate because the duodenum is acidic and there is a large predominance of glycine conjugates. Although much less work has been done on the absorptive phase of patients with pancreatic insufficiency, there is tentative evidence that defective phospholipid absorption, essential fatty acid deficiency, and protein malnutrition could impair the absorptive phase, particularly chylomicron formation. Although significant advances have been made in our understanding of factors responsible for malabsorption associated with pancreatic insufficiency, much remains to be done for the further delineation of defects. It is hoped that this will lead to further refinements of enzyme preparations and to new strategies of intervention.
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PMID:Digestive and absorptive phase anomalies associated with the exocrine pancreatic insufficiency of cystic fibrosis. 304 36

The increased oxalic acid absorption is a well documented finding in gastroenterological diseases. The malabsorption of bile acids and fat is important in the pathogenesis of the hyperoxaluria. The enteric absorption of 14C-labelled oxalic acid was measured in 49 patients with different diseases. The dihydroxy-trihydroxy-ratio of bile acids is significantly decreased in patients with hyperoxaluria over 20% of the ingested dosage. We didn't find any correlation between the excretion of oxalic acid and the intraduodenal pancreatic lipase activity.
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PMID:[Pancreatico-biliary secretion in enteral hyperoxaluria]. 325 36

A sandwich enzyme immunoassay has been developed for human pancreatic lipase using polystyrene balls coated with specific IgG as the first antibody and peroxidase-labelled IgG as the second antibody. The detection limit was 0.5 microgram/l. Good parallelism was observed with the curves obtained from standard lipase and lipase present in serum, pancreatic juice and duodenal contents, demonstrating that the assay may be used to measure the level of the protein in different biological fluids. Mean values of lipase in human sera were 12.3 +/- 6.8 micrograms/l in adults and 4.5 +/- 2.7 in newborns. In all cases a good correlation was found in serum between the catalytic activity and the enzyme immunoassay. Lipase is detectable in amniotic fluids at the 18th week of pregnancy but at a very low level (0.95 +/- 0.32 microgram/l). In pancreatic juices, lipase concentration was 14.6% of the total protein content. A study on cystic fibrosis patients showed a poor correlation between blood pancreatic lipase concentration and fat malabsorption underlying the difficulty in assessing pancreatic function by the measurement of serum pancreatic enzymes. The use of the lipase assay in duodenal contents would permit better assessment of pancreatic function in patients presenting a severe or borderline defect in fat digestion and absorption.
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PMID:Assay of human pancreatic lipase in biological fluids using a non-competitive enzyme immunoassay. 354 6

Protein, fat and carbohydrate absorption in preterm infants fed on human milk or formulae are reviewed. Even in the most premature infants absorption of protein is satisfactory. Nitrogen net absorption is about 85-90% of intake and results slightly lower with human milk than with formulae. The lower apparent digestibility of human milk is probably due to the poorly degraded IgA immunoglobulins and the rapid transit time. Lactose is well tolerated by the preterm infants despite the low lactase activity at birth. Glucose polymers, which have a low osmotic activity and are suitable for increasing carbohydrate intake of formulae, are well absorbed probably for the activity of salivary amylase and brush border glucoamylase, which have been shown to be well developed at birth. Premature infants absorb fat poorly. This malabsorption that increases with the lowering of gestational age is due to low pancreatic lipase activity and to low intraluminal concentration of bile salts. Due to its bile stimulated lipase activity, non-heat-treated human milk used at least in part is an effective method to improve fat absorption in preterm infants. Faecal energy determined using a calorimetric bomb appears to be a simple and an accurate method to predict faecal fat and avoiding expensive and cumbersome analysis.
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PMID:[Absorption of proteins, carbohydrates and fats in the preterm neonate]. 357 19

The etiopathogenesis and the clinical implications of fat malabsorption in preterm infants are reviewed. Low pancreatic lipase activity and impaired solubilization of lipids due to low intraluminal concentration of bile salts appear to be the main factors of the inadequate lipid absorption. The compensatory role of intragastric lipolysis could be important. Currently available informations suggest that, chylomicron formation and transport of lipids are not limiting steps, but the efficiency of these processes in neonates needs further investigations. Due to its bile-stimulated lipase activity, non-heat-treated human milk used at least in part, appears to be the most effective method to improve fat absorption in the preterm infant.
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PMID:[Fat absorption in the premature newborn infant]. 383 19

Patients with cystic fibrosis have been found to have abnormal serum concentrations of immunoreactive trypsin and abnormal activities of pancreatic isoamylase. A study was undertaken to discover whether activity of pancreatic lipase is also altered in cystic fibrosis. Serum from 23 patients with cystic fibrosis was assayed for immunoreactive trypsin and pancreatic lipase. Median serum pancreatic lipase activity was significantly lower in patients with cystic fibrosis than in controls, as was immunoreactive trypsin concentration (p less than 0.0001). Some patients had supranormal lipase concentrations but these were not always associated with absence of malabsorption. Serum pancreatic lipase activity is considerably changed in cystic fibrosis.
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PMID:Serum pancreatic lipase activity in cystic fibrosis. 640 37


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