Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: KEGG:D00046 (lactose)
 16,692 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The initial step of disaccharide dissimilation by Actinomyces viscosus serotype 2 strain M-100 was studied. Sucrase activity was found in the 3,000 X g particulate fraction and the 37,000 X g soluble fraction of the cells, whereas lactase activity was found almost exclusively in the 37,000 X g soluble fraction. Neither sucrase nor lactase activity was appreciable in the culture liquor. Sucrose phosphorylase, alpha-glucosidase, and polysaccharide synthesis activities were not observed in the soluble cell fraction. The sucrase was identified as invertase (EC 3.2.1.26; beta-D-fructofuranoside fructohydrolase). The lactase was identified as beta-galactosidase (EC 3.2.1.23; beta-D-galactoside galactohydrolase). The enzymes in the 37,000 X g soluble fraction were separable by diethylamino-ethyl-cellulose chromatography, giving one beta-galactosidase peak and one major and one minor invertase peak. Acrylamide gel electrophoresis showed different electrophoretic mobilities of the enzymes. The molecular weight of the beta-galactosidase is about 4.2 X 10(5) and that of invertase is about 8.6 X 10(4). The beta-galactosidase has a Km for lactose of about 6 mM and a pH optimum between pH 6.0 and 6.5. The major invertase component has a Km for sucrose of about 71 mM and a pH optimum between pH 5.8 and 6.3.
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PMID:Identification, separation, and preliminary characterization of invertase and beta-galactosidase in Actinomyces viscosus. 1 74

A simple and reliable test for the diagnosis of hyposucrasia is required, since this may be an unsuspected cause of long-standing gastrointestinal disorder. Furthermore little has been done to define the epidemiology of this condition, possibly because of the limitations of multiple blood-sampling. Breath hydrogen (H2) production after lactose ingestion is a reliable test for hypolactasia, and has now been measured after sucrose ingestion in eleven patients with various gastrointestinal symptoms. Six who had normal sucrase activity on jejunal biopsy produced no H2 after taking 50 g of sucrose. No H2 was produced in three patients with borderline hyposucrasia, either after 50 g sucrose or when retested using 100 g sucrose (two patients). However, the two patients with low jejunal sucrase activity showed rises of breath H2, after only 25 g glucose. Breath H2 measurement is a simple, accurate, and non-invasive test for diagnosing gastrointestinal symptoms due to hyposucrasia.
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PMID:Breath hydrogen in hyposucrasia. 5 37

Intestinal mucosa from 40 patients obtained by fiber-endoscopic biopsy was assayed for disaccharidases to determine suitability of this tissue for assay. The combined specimens from each patient provided 4.7-38.7 mg of tissue, adequate in all instances for duplicate determinations of protein, lactase, sucrase, and maltase. Tissue remained for assays of palatinase in 39 instances, trehalase and cellobiase in 37, and alkaline phosphatase in 22 cases. Twenty-four subjects had normal lactose tolerance tests and normal sucrase/lactase ratios. Thirteen patients with abnormal oral lactose tolerance tests were identified as having a primary low lactase activity on the basis of elevated sucrase/lactase ratios. This ratio was most helpful in making the diagnosis of a primary low lactase, since the mucosal specimens were not obtained from comparable areas. Tissue from three subjects with an abnormally low maltase was unsuitable for diagnosis. Endoscopic biopsy of mucosa appears to be satisfactory for disaccharidase assays in most instances.
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PMID:Adequacy of endoscopic biopsy specimens for disaccharidase assays. 10 20

Recent studies have demonstrated that the human intestinal enzymes of carbohydrate digestion and metabolism can be regulated by dietary sugars. These studies have utilized direct assay of intestinal mucosal enzyme activity. Mucosa has been obtained by the use of peroral jejunal biopsy techniques which provide 10-15 mg of mucosa in a safe, simple and reproducible manner. Dietary sucrose, as compared to dietary glucose, increases the activities of the jejunal disaccharidases, sucrase and maltase, but not lactase. Fructose reproduces the sucrose effect and appears to be the active principle in the sucrose molecule. Lactose deprivation or lactose feeding does not alter lactase activity. Fructose has been useful in treating one patient with sucrase-isomaltase deficiency. Jejunal glycolytic enzyme activities are also regulated by dietary sugars. Certain enzymes are highest with specific dietary carbohydrates, lower with other sugars and lowest on a carbohydrate-free diet. The regulation of human jejunal glycolytic enzyme activity takes place in hours, whereas the change in disaccharidase activity occurs in 2-5 days. The mechanism of this regulation is not known. Additional investigations have shown that jejunal glycolytic enzyme activities but not the disaccharidases are controlled by oral folic acid as well. This effect occurs within 1 day also. The mechanism is unknown. Large doses of folate have been of benefit in a few patients with certain glycolytic enzyme deficiency states. Preliminary studies have demonstrated that selected patients with chronic undiagnosed intestinal disorders fail to manifest an adaptive response of their jejunal glycolytic enzyme activities to dietary sugars. This condition has been termed a "maladaptation syndrome.".
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PMID:Diet and intestinal enzyme adaptation: implications for gastrointestinal disorders. 16 4

Introduction of plasmids carrying the lacY gene (lactose permease gene) into Yersinia enterocolitica results in cells being able to ferment both lactose and raffinose. Transfer of such plasmids into Escherichia coli C600 (lacY) confers ability to ferment lactose but not raffinose. Derivatives of C600 that ferment both lactose and sucrose (Lac+ Scr+ strains) are able to ferment raffinose, but do not grow well on raffinose minimal medium. Fermentation of raffinose by Lac+ strains of Y. enterocolitica, and by Lac+ Scr+ strains of E. coli, is explained in terms of transport of raffinose via the lac permease and subsequent breakdown catalyzed by invertase.
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PMID:Fermentation of raffinose by lactose-fermenting strains of Yersinia enterocolitica and by sucrose-fermenting strains of Escherichia coli. 34 38

The intestinal brush border disaccharidases separated by gel electrophoresis were studied after oral administration of a high sucrose or lactose diet to 11-day-old suckling rats during 3 days. Some modifications of the brush border protein and eyzyme patterns could be attributed to the effect of the basic diet: increase of glucoamylase, appearance of a weak sucrase activity and of a second molecular form of maltase. However, the specific action of a given disaccharide on the synthesis of the corresponding hydrolytic enzyme could be clearly demonstrated. Indeed, the electrophoretic pattern after sucrose or lactose feeding showed a marked increase of the protein bands corresponding to sucrase-isomaltase or lactase activities.
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PMID:Sucrase and lactase synthesis in suckling rat intestine in response to substrate administration. 41 23

A 10-year-old boy with severe familial lactose intolerance in infancy (vomiting, failure to thrive, lactosuria (5.25 g/l), sucrosuria (12 g/l), and aminoaciduria. Intestinal disaccharidases (including lactase and sucrase) normal at age 6 and 20 weeks. Oral lactose tolerance test at this age resulted in lactosuria (4.6 g/l); sucrose tolerance test, in sucrosuria (18.5 g/l). In contrast, intraduodenal lactose tolerance test gave only low lactose excretion in urine (0.28 g/l). He improved rapidly and had no lactosuria on intraduodenal feeding with citric acid milk. The lactosuria diminished as age increased, but was still higher at age 6 years than that of controls. He tolerated normal disaccharide containing food after 1.5 years of age. At 5.5 to 6 years, he had symptoms of lactose malabsorption, and an isolated lactase deficiency was proved. At 10 years, he still tolerates only limited amounts of milk. The defect in severe familial infantile lactose intolerance seems to be localized in the gastric mucosa. Acquired lactase deficiency can appear later in childhood in this syndrome.
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PMID:A boy with severe infantile gastrogen lactose intolerance and acquired lactase deficiency. 52 43

The concomitant appearance of enterokinase (EK) and trypsin activities in the human intestinal mucosa is indicative of the importance of EK as an activator of trypsinogen and therefore as the key enzyme in protein digestion. Enterokinase can be detected in fetal mucosa from the 26th week of gestation on, paralleling appearance of tryptic activity in meconium. The developmental pattern of EK activity increases with age. Between 26 to 30 weeks of gestation, the EK activity is only 6% and full term babies (40 weeks) 20% of that found in older children. In contrast, lactase studies during development show a lactase activity of only 30% in human fetuses between 26 to 34 weeks of gestation as compared to full term babies. During the same gestational period, sucrase and maltase activities reach 70% of the full term. In addition, the distributional pattern of EK differs from the disaccharidases, showing the highest activity in duodenum and the lowest in ileum, whereas disaccharidases are highest in jejunum with lower activity in duodenum and ileum. Differences in topographical distribution and time of appearance of EK and disaccharidases may be attributed to differences in orgin as well as subcellular localization of these enzymes. It is conceivable that the premature infant, between 26 to 30 weeks of gestation, is better equipped to deal with hydrolysis of alpha-glucosides than of lactose.
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PMID:Developmental pattern of small intestinal enterokinase and disaccharidase activities in the human fetus. 55 25

The effect of cows' milk protein (CMP) on the mucosal disaccharidases was investigated in 23 infants with acute infective enteritis. Jejunal biopsies performed before and after cows' milk provocation were subjected to histological examination and to mucosal disaccharidase enzyme (lactase, sucrase, and maltase) analyses. After milk challenge, changes in mucosal histology were observed in 18 infants, in 17 of them the levels of all 3 mucosal disaccharidases were much reduced. 10 of these infants developed diarrhoea and, in 6, the stools were positive for reducing sugar. It is concluded that CMP has a deleterious effect on the jejunal mucosa of young infants recovering from infective enteritis, so that in the management of young infants with sugar intolerance secondary to infective enteritis, CMP and lactose should be excluded from the diet.
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PMID:Cows' milk protein-sensitive enteropathy: an important contributing cause of secondary sugar intolerance in young infants with acute infective enteritis. 57 Mar 76

Lactase and sucrase activities were measured in jejunal biopsies from a group of alcoholic and nonalcoholic men of similar nutritional status, consisting of American blacks, and whites of northern European origin. When measured withing 10 days of alcohol withdrawal, sucrase activity was decreased by 33% in the alcoholics. Lactase activity was less than 1 U per g in 100% of the black and 20% of the white alcholics as compared to 50% of the black and none of the white control subjects. Lactase activity was virtually absent in 45% of the black alcoholics. A second jejunal biopsy after an additional 2-week period of alcohol abstinenece exhibited significant secondary increases in the activities of both disaccharidases. Oral administration of lactose (1 g per kg of body weight) resulted in significantly lower blood glucose concentration and higher incidence of adverse effects in alcoholics, mainly among the blacks. Although data from larger populations are needed to confirm our observations, these findings suggest that chronic alcohol ingestion decreases intestinal disaccharidase activities even in the absence of overt malnutrition. The decrease in enzyme activity produced by alcohol is associated with increased morbidity after lactose administration.
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PMID:Symptomatic intestinal disaccharidase deficiency in alcoholics. 83 22


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