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)

The relative effectiveness of commercially available plain yogurt (Y), sweet acidophilus milk (SAM), hydrolyzed-lactose milk (HLM), a lactase tablet (LT), and whole milk (WM) was evaluated in 10 lactose-intolerant black subjects. In a 5 x 5 Latin square design, hourly breath hydrogen excretion (BHE) was measured for 5 h after the subjects consumed the above products (18 g lactose in each except HLM, which had 5 g). Mean BHE (ppm) for Y, SAM, LT, HLM, and WM were 12, 37, 29, 18, and 33, respectively. There was a significant (p less than 0.05) positive correlation of 0.808 between the symptoms reported and the mean peak BHE. However, the correlation between the symptoms and diagnosis by history was not significant. Although Y was as effective as HLM in minimizing lactose maldigestion, it was the least accepted by the subjects in sensory evaluations. Results of this study also indicate that microbial endogenous lactase in yogurt is superior to exogenous commercial lactase in alleviating lactose maldigestion.
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PMID:Relative efficiency of yogurt, sweet acidophilus milk, hydrolyzed-lactose milk, and a commercial lactase tablet in alleviating lactose maldigestion. 211 Apr 14

Maturation of mechanisms for carbohydrate absorption occurs in a defined sequence during human fetal development. The intestinal enzymes, lactase, sucrase, maltase, isomaltase, and glucoamylase, are at mature levels in the term fetus. Mature levels of pancreatic amylase activity and glucose transport occur postnatally, and levels are low in both the term and preterm neonate. In the preterm infant, sucrase, maltase, and isomaltase are usually fully active, but lactase activity, which increases markedly from 24 to 40 weeks, may be low depending upon fetal age. Despite these developmental patterns, clinical lactose intolerance is uncommon. Postnatal adaptive responses to ingested carbohydrates lead to competent carbohydrate absorption. Inadequately absorbed carbohydrates are salvaged by colonic flora through fermentation of carbohydrates to hydrogen gas and short-chain fatty acids; the latter are readily absorbed by the colon. In this setting, carbohydrate tends to be absent from the stool. Noninvasive reflection of the status of carbohydrate absorption may be obtained from breath hydrogen testing, a technique of particular value in young infants.
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PMID:Development of carbohydrate absorption in the fetus and neonate. 257 23

A technique for repeated and noninvasive measurement of oro-cecal transit time in rats and other small animals is described. It is based on the incomplete digestion of carbohydrates such as lactose fed orally to the animals. Since the activity of the enzyme lactase is low in almost all species, lactose is fermented by colonic bacteria after it arrived in the cecum, thus producing hydrogen. Hydrogen is delivered to the lungs via the circulation and exhaled by the animal. An increase in breath hydrogen measured by means of an electrochemical cell or a gas-chromatograph indicates the arrival of the nutrient bolus in the cecum. The method can be used repeatedly in individual animals under various experimental conditions such as investigations of stress effects on gastrointestinal transit.
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PMID:Repeated noninvasive measurement of gastrointestinal transit in rats. 260 87

We have estimated lactose absorption indirectly by the breath H test to see if disaccharide exclusion is necessary for untreated celiac children. Lactose at 2 g/kg body weight (maximum 50 g) was administered to 42 infants and children (ranging in age from 9 months to 12 years) with flat small intestinal mucosa. Later, different amounts of lactose were given to determine the quantities tolerated and absorbed. One hundred percent of patients expired hydrogen more than 20 ppm over the baseline after an oral lactose load of 2 g/kg (maximum 50 g). Thirty-eight percent of them did not tolerate this quantity. Thirty-seven subjects aged 0-6 years absorbed and tolerated 0.5-1.5 g/kg (5-12.5 g total), and five patients aged 6-12 years absorbed and tolerated 0.5-0.6 g/kg (12-16.2 g total). We conclude that in many subjects with untreated celiac disease, lactase activity is sufficient for absorption and tolerance of the amount of lactose present in 250-300 ml cow's milk. Because of lactose's nutritional value, it should not be excluded unless necessary.
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PMID:Extent of lactose absorption in children with active celiac disease. 261 14

Seventy-three of 77 adult Singapore-born Chinese (95%) and 48 of 49 Canadian-born adult Chinese (98%) were demonstrated to be lactase deficient using the lactose breath hydrogen test. The similar prevalence of lactase deficiency in the Singapore- and the Canadian-born Chinese despite a larger estimated amount of daily milk ingestion in the Canadian-born Chinese (430 ml vs 157 ml) supports the concept that lactase deficiency, which is transmitted genetically, does not have an adaptable component related to the quantity of lactose ingested. When the lactose breath hydrogen test performed with a dose of 0.5 g/kg of lactose was compared with the test using a standard dose of 50 g of lactose, there was very little loss of sensitivity. In spite of the presence of lactase deficiency, only 32% of the Singapore subjects and 23% of the Canadian subjects had gastrointestinal symptoms when milk was ingested in the daily diet. Peak breath H2 was higher in females than males, but the difference was more significant in the Canadian cohort.
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PMID:Lactase deficiency in Singapore-born and Canadian-born Chinese. 274 48

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 adult lactase phenotype, lactose absorber or malabsorber, was determined using the lactose tolerance test with breath hydrogen assay in a group of Tuareg, a traditionally nomadic pastoralist population in the central Sahara. Out of a total of 118 subjects, 103 (87.3%) were lactose absorbers and 15 (12.7%) lactose malabsorbers. The frequency of the "lactase suppression gene" in this population sample was .357 (SD .043). The low frequency of lactase suppression in the Tuareg supports the hypothesis of natural selection in favor of the "lactase persistence gene" in milk-dependent nomadic pastoralist.
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PMID:Distribution of adult lactase phenotypes in the Tuareg of Niger. 308 81

The adult lactase phenotype, lactose absorber or malabsorber, was determined using the lactose tolerance test with breath hydrogen assay in a group of young, healthy, male Turks. Out of a total of 470 subjects, 135 (28.7%) were lactose absorbers and 335 (71.3%) lactose malabsorbers. The frequency of the 'lactase suppression gene' in this population sample was 0.844 (S.D. 0.012). The frequency of lactase suppression in Turkey is intermediate between that in southeast Europe and that in agricultural Arab populations and thus compatible with a genetic cline extending from Europe to southwest Asia.
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PMID:Distribution of the adult lactase phenotypes in Turkey. 309 18

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

Lactose digestion from and tolerance to flavored and frozen yogurts, ice cream, and ice milk were evaluated (20 g lactose/meal) in lactase-deficient subjects by use of breath hydrogen techniques. Unflavored yogurt caused significantly less hydrogen production than milk (37 vs 185 delta ppm X h, n = 9). Flavored yogurt was intermediate (77 delta ppm X h). Subjects were free of symptoms after consuming flavored and unflavored yogurts. Of seven commercial yogurts tested, all contained significant levels of microbial beta-galactosidase (beta-gal). In addition, eight subjects were fed meals of milk, ice milk, ice cream, and frozen yogurts with and without cultures containing high levels of beta-gal. Peak hydrogen excretion after consumption of frozen yogurt with high beta-gal was less than one-half of that observed after the other five test meals and intolerance symptoms were absent. Tolerance to frozen yogurt, produced under usual commercial procedures, was found to be similar to that of ice milk and ice cream.
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PMID:Lactose digestion from flavored and frozen yogurts, ice milk, and ice cream by lactase-deficient persons. 311 36


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