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)

Small intestinal lactase, sucrase and alkaline phosphatase activities were measured in histologically normal peroral intestinal biopsies from 477 individuals. Enzyme activities varied with age, sex, site of biopsy, and were lowest in post-weaning children and highest in young adults. Lactase activity does not decrease with advancing age.
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PMID:Intestinal lactase, sucrase and alkaline phosphatase in relation to age, sex and site of intestinal biopsy in 477 Irish subjects. 640 73

Activities of lactase and sucrase were determined in proximal, middle, and distal thirds of the jejunoileum of 15-wk-old male rats starved for 1, 2, and 3 days and in rats fed a high-sucrose diet for 24 h after 3 days of starvation. Sucrase activity (expressed per tissue protein or DNA as well as per intestinal segment) showed a progressive decrease during starvation in proximal and middle segments but not in the distal segment. Lactase activity expressed per tissue protein or DNA in all segments increased significantly. This was obviously due to the loss of tissue protein and DNA because total lactase activity per segment did not change. Refeeding the sucrose diet produced an increase of sucrase activity without influencing lactase activity. In serial tissue homogenate of jejunal villus-crypt columns prepared using cryostat sectioning, it was shown that, during starvation, activity of lactase (specific and total) increased in the upper and middle villus. Sucrase activity (specific and total) during starvation decreased and after refeeding increased in the lower and middle villus.
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PMID:Different effect of starvation on activity of sucrase and lactase in rat jejunoileum. 640 78

The control of weaning was studied in rat pups aged 17-24 days. The influence of two hormones, thyroxine (T4) and corticosterone, and the effect of declining intestinal lactase activity were evaluated. Hypothyroidism was induced by administration of n-propylthiouracil and hyperthyroidism was induced by injection of T4. Hypothyroid pups failed to begin nibbling chow while littermates injected with T4 weaned normally. Two abnormalities resulting from hypothyroidism, hypothermia and stunted incisors, were not responsible for the lack of weaning in hypothyroid pups. Hyperthyroidism did not cause precocious weaning. Glucocorticoid levels were manipulated by both adrenalectomy (ADX) and administration of corticosterone. ADX pups exhibited a delayed pattern of weaning while both ADX pups injected with corticosterone and sham-operated pups weaned normally. Corticosterone injected before its normal developmental surge did not cause precocious weaning. Lactase activity, measured throughout these experiments, did not consistently reflect the degree of weaning progression. We conclude that 1) the hormones, T4 and corticosterone, are necessary for the onset of weaning, but neither is a sufficient stimulus to initiate weaning, and 2) low lactase activity does not initiate weaning.
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PMID:Weaning in the rat: a study of hormonal influences. 640 84

Wistar rat jejunal disaccharidases were measured after feeding low fat, low fat + 5% pectin, low fat + 0.4% galactomannan, high fat, high fat + 5% pectin and high fat + 0.4% galactomannan diets for 16 weeks. All rats fed high fat diet had significantly lower jejunal sucrase and maltase levels when compared with their respective low fat groups. Lactase was significantly lowered in the high fat pectin group compared with the low fat pectin group, but was not significantly different when comparing the high fat or high fat galactomannan with their respective low fat groups. There was no significant difference in lactase, sucrase or maltase levels between the low fat groups, or between the high fat groups. We conclude that in Wistar rats an increased dietary fat level lowers jejunal sucrase, maltase and lactase levels, while the gel-forming substances pectin and galactomannan added at the levels of 5% and 0.4%, respectively, have no effect.
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PMID:Effects of dietary fat and gel-forming substances on rat jejunal disaccharidase levels. 640 82

The present study was performed in order to clarify controversies concerning the effect of thyroxine on lactase activity in young mammals. Lactase activity was determined in suckling rats with two reference systems (protein and DNA) after one and three thyroxine injections (0.2 mg/100 g body weight). In comparison with control animals lactase activity was decreased after thyroxine administration. The thyroxine effect was dosage-dependent: three injections caused a more profound and prolonged depression of lactase activity. In both thyroxine-treated groups lactase activity returned to age-specific normal levels before the low lactase activity of adult rats was attained. The transient thyroxine-induced changes of lactase activity were similar to the reference parameters protein and DNA.
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PMID:Temporary depression of lactase activity by thyroxine in suckling rats. 640 8

Jejunal fluid and mucosal tissue were obtained simultaneously from the same jejunal site in a group of 29 children by a modified biopsy procedure. Lactase, maltase, and sucrase activities were measured in both fluid and mucosal specimens using the same analytical method. The fluid enzyme activities showed highly significant positive correlations with the same enzyme activity in the relevant tissue samples. Relative concentrations of disaccharidase enzymes represented by sucrase: lactase activity ratios also showed a highly significant positive correlation between fluid and tissue. This close relation suggests that the mucosa is the sole or predominant source of disaccharidase activity in the intestinal fluid. The results of kinetic studies comparing tissue and fluid enzyme characteristics also indicate a mucosal origin for the fluid enzyme activities. We conclude that disaccharidase activities in jejunal fluid reflect closely local tissue values and that these measurements may be useful in assessing mucosal enzyme activity in infants in whom jejunal biopsy is not possible.
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PMID:Disaccharidase activities in jejunal fluid. 641 85

Lactase, sucrase, and alkaline phosphatase activities were measured in 833 peroral small intestinal biopsies from 373 patients with coeliac disease. Enzyme activities decreased with increasing degrees of mucosal damage. Enzyme activities in mucosae of patients with coeliac disease in remission were lower than in control groups matched for age, sex, and site of biopsy. Enzyme activities were measured in 81 patients when the mucosa was severely damaged and later when considerable improvement had occurred. Lactase activity remained low in 13% of patients under the age of 18 and in 33% of those over 18 years. Sucrase activity usually improved with histological recovery, but alkaline phosphatase activity tended to remain depressed in patients in whom lactase activity failed to improve.
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PMID:Intestinal lactase, sucrase, and alkaline phosphatase in 373 patients with coeliac disease. 642 95

The development of small intestinal enzymes (lactase, acid- and hetero beta-galactosidases, cellobiase, maltase, trehalase, and sucrase) was studied from 18 days after conception until birth in 24 rabbit fetuses, and during the postnatal period in 15 newborn, juvenile, and adult rabbits. Lactase, acid- and hetero beta-galactosidases, cellobiase, and trehalase activities increased significantly during the fetal stage, while changes in sucrase and maltase activities were not substantial. In the postnatal period, lactase and cellobiase activities decreased significantly whereas maltase, sucrase, and trehalase activities increased significantly to reach adult values by 30 days of age. The acid- and hetero beta-galactosidases remained unchanged.
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PMID:The fetal and postnatal development of small intestinal disaccharidases in the rabbit. 643 Nov 90

The addition of microbial beta-galactosidases directly to milk at mealtime represents a potential "enzyme replacement therapy" for primary lactase deficiency. We used the hydrogen breath test as the index of incomplete carbohydrate absorption to assess the efficacy of two enzymes--one from yeast, Kluyveromyces lactis (LactAid), and the other from the fungus Aspergillus niger (Lactase N)--to assist in the hydrolysis of 18 g of lactose in 360 ml (12 oz) of whole milk when consumed by an adult lactose malabsorber. Graded amounts of Lactase N produced, at best, a 53% relative reduction in breath hydrogen excretion, whereas quantitative elimination of excess hydrogen excretion was produced by 1 and 1.5 g of LactAid. A double-blind, controlled, crossover trial was subsequently performed in 50 healthy, unselected Mexican adults, to whom 360 ml of cow's milk was presented in the three forms in a randomized order: intact milk, prehydrolyzed milk, and milk to which 1 g of LactAid was added immediately before consumption. Among the 25 subjects with incomplete carbohydrate absorption with intact milk, adding enzyme 5-min before consumption produced a 62% reduction in breath hydrogen excretion, and symptoms of intolerance were significantly reduced. The feasibility of effective enzyme replacement therapy with a beta-galactosidase from K. lactis is demonstrated.
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PMID:Enzyme replacement therapy for primary adult lactase deficiency. Effective reduction of lactose malabsorption and milk intolerance by direct addition of beta-galactosidase to milk at mealtime. 643 67

To study the relation between dietary-induced increase of intestinal lactase activity and lactose absorption, 11-wk-old rats were fed either a high-starch (70 cal%), low-fat (7 cal%) diet or a low-starch (5 cal%), high-fat (73 cal%) diet for 7 days. Food intake and body weight changes were similar in the two dietary groups. In the first experiment, lactose absorption was studied in vivo after oral administration of 600 mg lactose (10% solution in water with added [3H]PEG) to rats fasted for 16 h. Groups of rats were killed at time 0 and at 1-h intervals for the next 3 h. Lactase activity and lactose absorption were significantly higher (P less than 0.01) in the high-starch group than in the low-starch group. In the subsequent experiment, 9-wk-old rats were fed the two isocaloric diets for 3 days. By use of the everted sac technique, we have demonstrated a significantly higher absorption of monosaccharides from lactose in the high-starch diet group; also, glucose transport was higher in the high-starch diet-fed animals. When Tris, an inhibitor of lactase, was added into the mucosal fluid, absorption of lactose was abolished and no effect was seen on glucose absorption (in vivo and in vitro). In both experiments, significant linear regression was established between lactase activity and lactose absorption. Our results thus show that the increase in lactase activity, induced by feeding a high-starch diet to adult rats, is accompanied by an increased capacity to hydrolyze lactose and absorb the constituent monosaccharides.
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PMID:Relation between dietary-induced increase of intestinal lactase activity and lactose digestion and absorption in adult rats. 643 52


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