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)

Lactose tolerance tests with breath hydrogen determination identified 39 lactose malabsorbers among 162 Jordanian Bedouins (24%), and 111 lactose malabsorbers among 148 subjects from the urban/agricultural zone of western Jordan and Palestine (75%). This highly significant difference supports the hypothesis that milk dependence in nomadic desert populations resulted in selective pressures in favour of the lactase persistence gene. Within the urban/agricultural zone which extends from the desert border in Jordan to the Mediterranean shore, a significant increase in the frequency of lactose malabsorbers (and hypolactasia gene frequencies) from east to west was observed. The suggested genetic cline is problably due to migration from the desert populations to the agricultural zone.
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PMID:Distribution of adult lactase phenotypes in Bedouins and in urban and agricultural populations of Jordan. 641 7

Large quantities of yogurt are consumed by some lactase-deficient population groups. We used breath hydrogen measurements to determine whether lactase-deficient subjects absorbed lactose in yogurt better than lactose in milk. Ingestion of 18 g of lactose in yogurt resulted in only about one third as much hydrogen excretion as a similar load of lactose in milk or water, indicating a much better absorption of lactose in yogurt. Ingestion of yogurt also resulted in fewer reports of diarrhea or flatulence than did a similar quantity of lactose ingested in milk or a water solution. The enhanced absorption of lactose in yogurt appeared to result from the intraintestinal digestion of lactose by lactase released from the yogurt organisms. This autodigesting feature makes yogurt a well-tolerated source of milk for lactase-deficient persons and may explain the widespread consumption of yogurt by lactase-deficient population groups.
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PMID:Yogurt--an autodigesting source of lactose. 641 39

Unsuspected bacterial contamination of the small intestine was indicated by breath hydrogen testing in nine patients aged 2 to 34 months during physical examinations for chronic diarrhea and abdominal pain. Elevated bacterial counts of questionable significance were found in duodenal aspirates before and after antibiotic treatment. There was no evidence of bile salt deconjugation or structural changes in the small intestine by light or electron microscopy. This may indicate that the site of colonization is distal to the biopsy site. Breath testing indicated lactose malabsorption in all patients, and four of five patients tested also malabsorbed sucrose. Duodenal disaccharidase levels in all patients were within the normal ranges, but in eight patients the lactase-sucrase ratio was greatly elevated (0.80 +/- 0.36; normal less than 0.45). Dietary restriction alone did not cause complete cessation of symptoms, whereas all patients responded dramatically to oral antibiotic therapy. When patients were well, the lactase-sucrase ratio had returned to normal in those tested, and all nine had normal lactose and lactulose breath hydrogen tests. Unsuspected bacterial contamination of the small intestine, which is easily detected using the breath hydrogen test, may be more commonly associated with chronic diarrhea in children than has been previously realized. In such cases, therapy should be directed at removing the contamination.
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PMID:Bacterial contamination of the small intestine as an important cause of chronic diarrhea and abdominal pain: diagnosis by breath hydrogen test. 643 89

Lactose absorption capacity was determined by lactose tolerance tests with breath hydrogen determination in 102 healthy, adult, Hungarian pairs of twins in order to test monogenic Mendelian inheritance of the absorptive lactase phenotypes, lactose absorber and lactose malabsorber. Of the total, 52 pairs were monozygous (MZ) and 50 dizygous (DZ) twins of identical sex. All MZ twins were concordant with respect to lactase phenotype. Among DZ twins, the distribution of lactase phenotypes was in agreement with Hardy-Weinberg expectations derived from the frequencies of the hypolactasia gene in DZ and MZ twins, and in the general Budapest population. In the second part of the study, three commonly used methods of lactose tolerance testing, the blood glucose, the blood galactose, and the breath hydrogen tests, were compared in 49 pairs of twins concordant for lactase phenotype. Blood galactose concentration showed the greatest and only significant difference between the intrapair correlation coefficients of MZ and DZ, and no overlap between lactose absorbers and lactose malabsorbers. The intrapair correlation coefficients of peak breath hydrogen concentration in MZ and DZ twins did not significantly differ from zero, but the resolution of lactase phenotypes was satisfactory. Differences in glucose absorption and concentration in lactose absorbers and malobsorbers overlapped considerably, and among lactose absorbers correlation coefficients in DZ were higher than in MZ twins. In MZ and DZ twins, the difference in concordance and constancy of lactose intolerance symptoms was not significant.
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PMID:A study of lactose absorption capacity in twins. 643 76

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

The use of fermented dairy foods is common in areas of the world where lactase deficiency is prevalent. Recently, we have shown that the digestion of lactose from yogurt is enhanced as compared to that from milk. This enhanced digestion is apparently due to inherent B-galactosidase in yogurt which is active in the gastrointestinal tract after consumption of the yogurt. Furthermore, yogurt is well tolerated by lactase-deficient subjects resulting in little or no gastrointestinal distress. Since other fermented and microbial-containing dairy foods are consumed worldwide and may also contain some "lactase" activity, we chose to evaluate the digestion of lactose from three of these products: pasteurized yogurt, cultured milk (buttermilk), and sweet acidophilus milk. Breath hydrogen techniques were used to evaluate lactose malabsorption in nine lactase-deficient subjects. The studies demonstrated that yogurt is unique among the products tested in enhancing the digestion of lactose. Furthermore, pasteurization of yogurt eliminated the enhanced digestion of lactose, reduced the inherent lactase activity of the yogurt by 10-fold and reduced cell counts by 100-fold. Interestingly, eight of nine subjects fed cultured milk experienced gastrointestinal distress, whereas all subjects fed pasteurized yogurt were symptom free, even though the amount of malabsorbed lactose was similar.
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PMID:Lactose malabsorption from yogurt, pasteurized yogurt, sweet acidophilus milk, and cultured milk in lactase-deficient individuals. 643 26

Lactose-absorption capacity was examined in 275 apparently healthy Polish adolescents and adults (214 females and 61 males with an average age of 29.1 years) using a field version of the lactose-tolerance test with breath hydrogen determination. In the total group, 172 lactose absorbers (62.5%) and 103 lactose malabsorbers (37.5%) were identified. Reported milk intolerance and symptoms of lactose intolerance were significantly more frequent in lactose malabsorbers. Subdivision according to the birthplaces of the probands' grandparents did not reveal significant regional differences. The unexpectedly high frequency of lactose malabsorption is further evidence for concentric genetic clines of lactase gene frequencies extending from southern Scandinavia, the area with the lowest observed frequencies of selective adult hypolactasia, to the south and the east.
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PMID:Prevalence of primary adult lactose malabsorption in Poland. 646 37

A total of 308 healthy Italian adults (192 females, 116 males; mean age 29.2 yr) were examined using a field version of the lactose tolerance test with breath hydrogen determination. Two geographical groups were formed according to the birth places of the probands' grandparents: 208 subjects from northern Italy (mainly from the regions of Piemonte, Lombardia, and Veneto) and 100 probands from Sicily. Lactose malabsorption was diagnosed in 106 subjects in group "north" (51%) and in 71 subjects in group "Sicily" (71%). Awareness of milk intolerance was more frequent in lactose malabsorbers. The incidence of diarrhea after the test dose of lactose was significantly higher in "aware" lactose malabsorbers, when compared with persons of the same group who had not experienced milk intolerance. The significant difference in lactose malabsorption frequency between northern Italy and Sicily is further evidence of a north-south gradient of lactase gene frequencies in Europe.
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PMID:Prevalence of primary adult lactose malabsorption and awareness of milk intolerance in Italy. 669 Dec 85

Breath hydrogen production was used as a measure of lactose malabsorption in human test subjects following the consumption of both heated and unheated cultured yogurt. Less hydrogen was produced when the subjects consumed the unheated cultured yogurt than when they consumed the heated product, indicating that lactose hydrolysis was improved in the small intestine of the individuals consuming the unheated cultured yogurt. Lactase activity in yogurt samples was increased in the presence of bile. Yogurt starter bacteria growing in milk normally do not hydrolyze more lactose than needed for their growth. However, the increased lactase activity in the presence of bile indicates that these bacteria could function as a source of lactase to hydrolyze lactose in the small intestine even though the organisms themselves are not expected to grow in that environment.
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PMID:Effect of viable starter culture bacteria in yogurt on lactose utilization in humans. 670 96

The breath hydrogen (H2) test for lactose absorption capacity is a simple, noninvasive method for the determination of the adult lactase phenotypes, lactose absorber and malabsorber, in healthy subjects. Two breath H2 tests with a load of 50 g lactose monohydrate were performed on 25 healthy adult lactose malabsorbers in order to determine the validity of simplified versions of the test for field studies. A high variability of peak H2 excretion times, rapid changes in breath H2 concentrations and a significant correlation of intraindividual peak H2 excretion times were observed. High fasting excretion of H2 in breath was a frequent cause of misclassification of probands. It is recommended that at least three breath samples per proband should be collected in field studies of lactose absorption and that special diagnostic criteria be applied in classifying subjects with high initial H2 excretion.
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PMID:Breath hydrogen test for lactose absorption capacity: importance of timing of hydrogen excretion and of high fasting hydrogen concentration. 671 77


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