Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.108 (lactase)
 2,133 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To compare the tropic effect of different dietary nutrients on mucosal adaptation in the jejunum and ileum, adult rats were submitted to a 96-h period of starvation and refed isocaloric liquid diets (1.5 kcal ml-1) containing either protein (casein), carbohydrate (starch) or lipids. In the jejunum, 4 days of starvation caused mucosal hypoplasia, villus and crypt shortening and a decrease in the total activity of disaccharidases with the exception of lactase which was markedly enhanced. In contrast, mucosal hypoplasia was incomplete in the ileum which exhibited an increase in crypt depth and in the specific and total activities of disaccharidases and of aminopeptidase. Compared with protein and carbohydrates, lipids exerted the strongest stimulatory effect for mucosal regeneration. In the jejunum as well as in the ileum, mucosal mass parameters, villus length, crypt depth and lactase activity did reverse towards their initial value within 1-3 days of refeeding lipids, even though the animals received only one-third of their normal daily caloric intake. Our results indicate that the pattern of response to fasting differs between the proximal and distal small intestine, and that the intestinal changes induced by starvation are rapidly reversed by refeeding small amounts of a diet rich in fat.
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PMID:Refeeding after starvation in the rat: comparative effects of lipids, proteins and carbohydrates on jejunal and ileal mucosal adaptation. 212 4

Some diets exert a considerable influence on porphyrin metabolism and induction of microsomal liver enzymes in experimental porphyria induced by hexachlorobenzene (HCB). As HCB and its metabolites come into direct contact with intestinal mucosa, this study investigated the changes in the activities of intestinal disaccharidases and gamma-glutamyl transferase in a model of HCB-induced porphyria. The effects of different diets on enzymatic activities during HCB intoxication were also studied. HCB was administered by gastric tube at 3.5 mmol/kg body weight daily for 90 and 61 days. HCB intoxication strongly diminished the activities of intestinal lactase, maltase, sucrase, cellobiase and trechalase. Carbohydrate diets (with 78 weight % glucose or starch), given simultaneously with HCB treatment, exerted a protective effect on disaccharidase activities. These regimens maintained cellobiase and trechalase within the normal levels and even increased maltase. High-fat/high-protein diets (with 30% either butter or sunflower oil and 31% casein) aggravated the decrease of all disaccharidases. In contrast with the decrease in disaccharidase activity, intestinal gamma-glutamyl transferase was increased, suggesting multiple mechanisms for the action of HCB intoxication on the intestinal enzyme system. Diet had a pronounced modifying effect.
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PMID:Changes in some intestinal enzyme activities in experimental hexachlorobenzene-induced porphyria and modifying effects of diet. 288 67

Cow's milk allergy in the first year of life is one of the most common problems faced by pediatricians. Both over and under diagnosis is seen. Cow's milk allergy, which is IgE-mediated should be differentiated from milk intolerance due to lactase deficiency or other causes. Cow's milk allergy may effect the gastrointestinal tract, respiratory tract, skin or blood. Anaphylaxis may occur. Diagnosis is made primarily on clinical grounds but skin tests and/or RAST are of value. Elimination and subsequent challenge confirms the diagnosis but challenge is not always necessary. Challenge should not be performed if there is evidence of anaphylaxis. Avoidance is the mainstay of treatment and breastfeeding is the optimal choice. Since antigenically intact cow's milk protein can pass into the breast milk, the mother should avoid excessive intake of milk products herself while breast feeding. Alternatives to breast milk such as soy formulas or hydrolysed casein or whey formulas may be used. Twenty-five percent of milk-sensitive infants are also allergic to soy protein. Hydrolysed casein formulas are more hypoallergenic but are expensive and less palatable. Hydrolysed whey formula, which is comparable in expense to soy formulas but is less allergenic, may prove of value in the management of the milk-allergic infant as well as for prophylaxis in infants from susceptible parents. Parents of infants born to families with bilateral atopic histories may be able to prevent milk allergy by using dietary manipulations which include decreased prenatal maternal milk intake and while breast feeding as well as careful avoidance of milk products in the infant's diet during the first year of life.
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PMID:Allergy to cow's milk in the first year of life and its prevention. 305 24

The administration of a carbohydrate-containing diet for 24 hours to rats previously fasted for 3 days led to a twofold increase in total intestinal sucrase and sucrase specific activity. The specific activity of maltase was similarly increased, but lactase activity was unaffected. The sucrose-containing diet led to a greater increase in sucrase than maltase activity, whereas the converse was true of the maltose-containing diet. A carbohydrate-free isocaloric diet led to a slight increase in the total intestinal sucrase, but sucrase specific activity was unchanged. Assay of sucrase activity of mixed homogenates from casein-fed and sucrose-fed rats or fasted and sucrose-fed animals yielded activities that were additive. The Michaelis constant (Km) of the enzyme hydrolyzing sucrose was similar in the fasted, casein-fed, and sucrose-fed rats. The maximal velocity (Vmax) was twice greater in sucrose-fed as compared to casein-fed or fasted rats, suggesting an increased quantity of enzyme subsequent to sucrose feeding. Adrenalectomized rats maintained on 1.0% salt intake had sucrase and maltase levels comparable to those of controls. Steroid administration did not significantly increase their activities. The response to sucrose feeding was similar in both control and adrenalectomized rats, indicative of the absence of steroidal control on sucrase and maltase activity in the adult animal. Studies using intestinal ring preparations indicated that sucrose hydrolysis by the intact cells proceeded more rapidly when animals were fed sucrose. Additional corroboration of the physiologic significance of the increased enzyme levels in homogenates was afforded by intestinal perfusion studies. Sucrose hydrolysis increased twofold and fructose absorption fourfold in animals fed sucrose when compared to either fasted or casein-fed rats.
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PMID:Effect of diet upon intestinal disaccharidases and disaccharide absorption. 601 58

Female rats of the Wistar strain, weighing 40-60 g were used to study the effect of fish meals (Coryphaenoides rupestris, Chimaera monstruosa and Merluccius merluccius) on the disaccharidases and alkaline phosphatase in the small intestine in relation to the control group which consumed casein. Fish meal diets diminished lactase and alkaline phosphatase activity, the latter being most remarkable in animals fed Ch. monstruosa meal, while no statistical variations in maltase and sucrase activity were observed. Maltase, sucrase and lactase activity of animals fed Ch. monstruosa meal dropped in comparison with those fed C. rupestris meal, while the alkaline phosphatase activity showed no significant changes.
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PMID:[Effect of various fish meals on disaccharidases and alkaline phosphatase of the small intestine in rats]. 681 26

The in vitro and in vivo production of hydrogen gas (H2) from various carbohydrates or proteins has been examined in normal rats and in rats infected with the nematode Nippostrongylus brasiliensis. Normal rat fecal homogenates were capable of producing H2 in vitro from glucose, sucrose, xylose, lactulose, bovine serum albumin, or casein hydrolysate. Direct injection of glucose, sucrose, xylose, lactulose, bovine serum albumin, or casein hydrolysate into the cecum of normal rats resulted in approximately twice as much H2 production in vivo than when these same carbohydrates or proteins were administered to the normal rats by gavage. Partial small intestinal villous atrophy was produced by infecting rats with the nematode N. brasiliensis. Impaired small intestinal cell function and evidence of malabsorption in the nematode-infected rats included: (a) decreased activity of intestinal cell lactase (-43%), sucrase (-33%), and alkaline phosphatase (-46%); (b) decreased gut sac uptake of 3-O-(methyl-3H]-D-glucose (-21%) or 1-[carboxyl-14C]-aminocyclopentane-1-carboxylic acid (-28%); and (c) increased (+ 64%-561%) 14CO2 production after D-[U-14C]xylose administration. These rats produced approximately twice as much H2 after gavage administration of glucose, sucrose, xylose, bovine serum albumin, or casein hydrolysate compared with normal rats. The present study suggests that H2 analysis may be useful in the evaluation of small intestinal malabsorption states in rats.
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PMID:Use of hydrogen gas (H2) analysis to assess intestinal absorption. Studies in normal rats and in rats infected with the nematode, Nippostrongylus brasiliensis. 728 87

This study was done to clarify the effects of dietary wheat gluten on the hepatotoxic action of D-galactosamine (GalN) and endotoxin (Etx). Male Wistar rats fed a high casein or high gluten (supplemented with L-Lys and L-Thr) diet were injected with GalN or Etx, and the plasma glutamate oxaloacetate transaminase, glutamate pyruvate transaminase, and lactase dehydrogenase activities were examined 20 h later. In rats fed the high gluten diet, these enzyme activities were lower than in the high casein group after injection of 800 mg/kg of GalN. But such a difference between the casein and gluten groups was not clear when they were treated with 400 mg/kg of GalN nor observed even after injection of Etx or Etx+GalN (400 mg/kg). Similarly these was no difference in the plasma concentrations of Etx, tumor necrosis factor-alpha, or interferon-gamma in the rats receiving an injection of 800 mg/kg of GalN between both dietary groups. These results suggest that dietary gluten affords protection against hepatic injury by a high dose of GalN but not by a low dose of GalN and/or Etx.
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PMID:Effects of dietary gluten on the hepatotoxic action of galactosamine and/or endotoxin in rats. 890 Nov 1

The thermal stability of enzymes lactase and invertase in dried, amorphous matrices of sugars (trehalose, maltose, lactose, sucrose, raffinose) and some other selected systems (casein, PVP, milk) was studied. The glass transition temperature (Tg) was limited as a threshold parameter for predicting enzyme inactivation because (a) enzyme inactivation was observed in glassy matrices, (b) a specific effect of enzyme stabilization by certain matrices particularly trehalose was observed, and (c) enzyme stability appeared to depend on heating temperature (T) "per se" rather than (T-Tg). For these reasons, a protective mechanism by sugars related to the maintenance of the tertiary structure of the enzyme was favored. A rapid loss of enzyme (lactase) activity was observed in heated sucrose systems at T > Tg, and this was attributed to sucrose crystallization since it is known that upon crystallization the protective effect of sugars is lost. Thus, the stabilizing effect could be indirectly affected by the Tg of the matrix, since crystallization of sugars only occurs above Tg. Trehalose model systems (with added invertase) showed an exceptional stability toward "darkening" (e.g., non-enzymatic browning) when heated in the dried state to elevated temperatures and for long periods of time.
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PMID:Glassy state and thermal inactivation of invertase and lactase in dried amorphous matrices. 941 44

This update focuses on the bioavailability of dietary calcium for humans. Fundamentals of calcium metabolism, intestinal absorption, urinary excretion and balance are recalled. Dietary factors, especially lactose and other milk components, influencing calcium bioavailability at intestinal and renal levels are reviewed. A critical examination of all the methods used for evaluating calcium bioavailability is made. This includes in vitro assays, classical and isotopic balances, urinary excretion, isotope labeling in the urine, plasma and bones, long term evaluation of bone mineralization and the use of biological bone markers. Importance and advantages of animal models are discussed. The state of the art in the comparative bioavailability of calcium in foods is detailed including a comparison of sources of calcium (dairy products and calcium salts) in human studies and in some animal studies, casein phosphopeptides, proteins, lactose and lactase and their relation with calcium bioavailability (in humans and rats). An update on the consumption of dairy products and bone mass is presented. Emphasis on peculiarities and advantages of calcium in milk and dairy products is given.
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PMID:The bioavailability of dietary calcium. 1075 38

The dietary effects of two high protein diets from two species of sea urchin (Paracentrotus lividus and Echinus esculentus) as compared to a reference protein such as casein on serum lipid levels and on intestinal disaccharidases and alkaline phosphatase were studied. After 23 days, the containing the two sea urchins as diets compared to casein decreased the cholesterol level and significantly increased the HDL-cholesterol in serum. The consumption of Echinus esculentus meal produced a significant decrease in lactase activity. The intestinal alkaline phosphatase activity increased not significantly in animals fed on the sea urchin meal.
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PMID:Effects of sea urchin-based diets on serum lipid composition and on intestinal enzymes in rats. 1132 29


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