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)

Individuals with sufficient intestinal lactase hydrolyze ingested lactose to galactose and glucose and these monosaccharides are absorbed. Lactose is not digested completely when intestinal lactase activity is low and the disaccharide is malabsorbed. Breath hydrogen excretion after lactose ingestion is used commonly to diagnose lactose malabsorption. However, no direct tests are currently used to assess lactose absorption. We tested a new method of assessing lactose absorption in 26 healthy individuals. Each subject ingested 50 g of lactose. Participants were evaluated for lactose malabsorption using a standard 3-h breath hydrogen test. In addition, the urinary excretions of galactose, lactose, and creatinine were quantitated for 3-5 h after lactose ingestion. On the basis of breath hydrogen analysis after lactose ingestion, 12 individuals were lactose malabsorbers (defined as a rise in the breath hydrogen concentration of greater than 20 parts per million above the baseline value). The 14 subjects who did not malabsorb lactose by breath hydrogen testing (defined as a rise in the breath hydrogen concentration of less than or equal to 20 parts per million above the baseline value), had significantly more galactose in their urine 1, 2, and 3 h after lactose ingestion than lactose malabsorbers. The ratio of excreted lactose to excreted galactose was significantly decreased in lactose absorbers compared with lactose malabsorbers (p less than 0.001). Determination of the ratio of urinary galactose to urinary creatinine separated lactose absorbers from lactose malabsorbers completely (p less than 0.001). We conclude from this study that the determination of urinary galactose, urinary lactose/galactose ratio, and urinary galactose/creatinine ratio may be used to assess lactose digestion and absorption in healthy adults.
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PMID:Assessment of lactose absorption by measurement of urinary galactose. 277 42

The authors present the cases of 4 children who suffered from saccharose-isomaltose malabsorption. The clinical symptoms developed following artificial feeding. The diagnosis was made by the histological examination of small intestine samples and with the simultaneous measurement of disaccharide enzyme activity. The histological picture and activity of lactase enzyme were practically normal. The saccharose H2 breath test gave only in 1 case positive result. The treatment of the children required saccharose-free diet. The tolerance showed no improvement during the treatment.
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PMID:[Current diagnostic method for saccharose-isomaltose malabsorption]. 278 45

The tests with lactose loading followed by the assay of blood sugar were conducted in 500 normal subjects, aged from 18 to 89 years, and 262 patients with gastro-intestinal diseases, aged from 25 to 55 years. When lactose malabsorption was detected, aspiration biopsy of the small intestine mucosa was performed followed by the study of the structure and the level of a number of disaccharidases (lactase, maltase, saccharase). Lactose malabsorption was detected in 72 (14.4%) out of 500 normal subjects (10.6%--aged 18-59, and 20%--aged 60-89 years), among them there were 12.5% of Russians, 13% of Byelorussians and 5.8% of Ukrainians (aged 25-55 years). The secondary lactose malabsorption was recorded in 44% of patients with ulcerative colitis, in 33% of patients with chronic enterocolitis, in 11.5% of patients with gastric ulcer, in 8% of those with duodenal ulcer, in 23.5% of patients with chronic gastritis attended by lowered secretory function, and in 8% of those with enhanced secretory function.
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PMID:[Current problems of lactase deficiency]. 296 77

The results of previous investigations of lactase deficiency and lactose malabsorption are reviewed. It showed that lactase activity and its decline in animals and humans is controlled genetically, but also that its phenotypic expression as lactose malabsorption is influenced by nongenetic factors: adaptation, biological (circadian) rhythmicity, hormones, gastrointestinal functions, and nutritional components can alter the response to lactose intake.
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PMID:Lactase deficiency and lactose malabsorption. A review. 308 62

The object of this study was to compare the indirect diagnostic methods on the basis of urinary galactose determination in the diagnosis of lactose malabsorption with the actual lactase activities. One hundred and seven patients were studied. The specificity and sensitivity of the strip test were 97%. With 30% actual prevalence the positive predictive value was 94%, and the negative predictive value was 99%. In common prevalences of hypolactasia the strip test was reliable.
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PMID:Strip test is reliable in common prevalences of hypolactasia. 311 Sep 39

The effects of oral enzyme replacement therapy on breath hydrogen excretion and symptoms after milk ingestion were studied in lactase-deficient patients. Sixteen symptomatic patients underwent interval hydrogen breath tests using whole milk as substrate. Each study was repeated with the addition of 250 mg of beta-D-galactosidase derived from Aspergillus oryzae (Lactrase) given orally with the milk. Subsequently seven of those 11 patients who did not normalize their hydrogen excretion with 250 mg of Lactrase were available to be restudied with a 500-mg dose. Mean cumulative and peak hydrogen excretions were calculated for the baseline (milk alone), 250 mg, and 500 mg Lactrase groups. Significant (p less than or equal to 0.05) decreases in cumulative and peak hydrogen excretion were noted between the 500 mg Lactrase versus the baseline group, but not between the 250 mg versus baseline group. Five of the 16 (31%) symptomatic lactase-deficient patients normalized their hydrogen excretion after 250 mg of Lactrase; four of seven (57%) who had not normalized on 250 mg, normalized their hydrogen excretion with 500 mg of Lactrase. A different pattern was observed in the incidence of symptoms. Five of the nine patients (56%) whose hydrogen excretion normalized with the addition of Lactrase at either dosage became asymptomatic after milk ingestion; in addition, three patients who did not normalize their hydrogen also became asymptomatic. We conclude that oral Lactrase in sufficient dosage temporarily reverses lactose malabsorption in some patients.
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PMID:Does oral enzyme replacement therapy reverse intestinal lactose malabsorption? 311 Dec 43

A total of 852 healthy Chinese children from 1 month to 14 years of age were investigated for lactose malabsorption using the breath hydrogen test. A lactose load of 2 g/kg was administered to 528 children and 1 g/kg to another 324 children. The incidence of lactose malabsorption was significantly different among various age groups and between the two different lactose dosages. While the incidence of malabsorption increased strikingly from the age of 3 to the age of 5 years, the age effect remained constant after the age of 6 years. The lactose load of 2 g/kg induced a higher incidence of malabsorption in study subjects than 1 g/kg did, and the dose effect increased for those aged below 5 years and decreased above 5 years. Small-intestinal lactase was also studied in 34 children aged from 2 months to 15 years. The lactase activity was highest in children 2 years old or younger, gradually decreasing with increasing age. In conclusion, lactase activity in Chinese children decreases gradually after 3 years of age, a finding that correlates well with the results of the breath hydrogen test.
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PMID:Lactose malabsorption and small-intestinal lactase in normal Chinese children. 312 31

Fifty-one adult patients with coeliac disease, verified by a proximal small-intestinal biopsy, were investigated. Before treatment with a gluten-free and low-lactose diet 52% showed a slight rise in blood glucose during the lactose tolerance test. Seventy-nine per cent of these patients had watery stools, and 88% had three or more bowel movements a day--statistically significantly different from the coeliac patients with a normal lactose tolerance test. After treatment 12% had a flat lactose tolerance curve. Half of them (6%) had specific lactase deficiency. This is approximately the incidence of lactose malabsorption in the general Danish population. The small-intestinal disaccharidases and alkaline phosphatase levels were severely depressed before treatment. After treatment the activities increased, but not to normal. We conclude that lactose malabsorption is a clinically important condition in many patients with untreated coeliac disease, giving rise to more frequent and more watery stools. In well-treated coeliac disease lactose malabsorption is not commoner than in the general population. The lactose activity in a proximal intestinal biopsy specimen was found to be an unreliable indicator of lactose malabsorption in coeliac disease.
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PMID:Incidence and clinical significance of lactose malabsorption in adult coeliac disease. 313 38

The efficacy of lactase by Kluyveromyces lactis in hydrolyzing milk lactose and reducing milk intolerance symptoms was tested in 52 proved lactose malabsorbers. The enzyme was added to milk administered to the patients, and H2 breath excretion (as an index of carbohydrate malabsorption), was determined by gas chromatograph technique, and milk intolerance symptoms were recorded. H2 mean excretion was 78.3 +/- 5.49 ppm after administration of intact whole milk 500 ml (test A), 43.5 +/- 4.99 ppm when lactase 2000 U was added to milk 500 ml immediately before administration (test B); 36.7 +/- 5.01 ppm when milk 500 ml was incubated for 12 h with lactase 1000 U (test C), and 29.7 +/- 4.35 ppm when the incubation was prolonged for 24 h (test D). Symptoms score was: test A = 5.85 +/- 0.56, test B = 3.71 +/- 0.45, test C = 2.77 +/- 0.63, test D = 1.7 +/- 0.68. A correlation index of r = 0.44 (p less than 0.01) was obtained between reduction in H2 mean excretion and reduction in symptoms score of a single individual. The addition of this lactase to milk seems to be effective in correcting lactose malabsorption, thus representing a convenient approach in milk intolerance.
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PMID:Efficacy of addition of exogenous lactase to milk in adult lactase deficiency. 313 8

Because of autodigestion of lactose by its endogenous bacteria, the lactose in yogurt is better absorbed than other sources of lactose in lactase-deficient subjects. To investigate possible differences among brands of yogurt in this autodigesting capacity, we challenged eight lactose-malabsorbing subjects with 20 g oral lactose and three different brands of yogurt (Borden, Dannon, and Royal Maid). As a quantitative measure of carbohydrate absorption, end-alveolar breath samples were collected for 8 h and assayed for hydrogen gas. Symptoms were scored by questionnaire every 30 min for 8 h. The cumulative breath H2 and the area under the discontinuous curve of breath-H2 concentration decreased relative to lactose results after ingestion of Dannon and Royal Maid but not after Bordon yogurt. no correlation of symptoms with the degree of carbohydrate malabsorption was demonstrated. We conclude that the lactase activity of yogurt cultures varies among brands.
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PMID:All yogurts are not created equal. 334 55


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