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)

Subjects deficient in lactase may experience bloating, cramps and diarrhoea after ingesting milk, due to the unhydrolysed and poorly-absorbed lactose. The diarrhoea may result from an osmotic effect of the lactose itself or its poorly-absorbed acidic products of fermentation (Weijers, van de Kamer & others, 1961; Christopher & Bayless, 1971), possibly together with an alteration of sodium and water absorption due to the lowered colonic pH (Rousseau & Sladen, 1971). Laxation by lactulose (1-4-beta-galactosidofructose) may operate through an analogous mechanism. The drug is a synthetic dissaccharide which, in oral doses of 10-20 g, relieves chronic constipation (Wesselius-de Casparis, Braadbaart & others, 1968). It is neither hydrolysed by intestinal dissaccharidase (Dahlqvist & Gryboski, 1965) nor absorbed in the gut, but it is converted in the colon mainly to lactic and acetic acids by various bacteria including Lactobacillus acidophilus. Apart from the increased osmotic effect, the pH in the proximal colon falls markedly (Bown, Gibson & others, 1974), and larger doses may reduce stool pH. Weijers & others (1961) inferred that the acidic products formed from lactose in the colon stimulate propulsion, and K.S. Liem (Philips-Duphar) suggested to us that lactulose may relieve constipation partly by stimulation of propulsion due to the lowered pH. The experiments described below support this view.
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PMID:Intestinal pH and propulsion: an explanation of diarrhoea in lactase deficiency and laxation by lactulose. 0 91

Breath hydrogen (H2), collected by end-expiratory sampling, was measured in twenty-five patients with abdominal symptoms or diarrhoea after ingesting 50 g. of lactose. This was compared with established tests of hypolactasia. Fifteen patients with a blood-glucose rise of more than 20 mg. per 100 ml. had less than 4 parts per million (p.p.m.) rise in breath H2 at 2 hours. In contrast, ten patients with blood-glucose rises of less than 20 mg. per 100 ml. had more than a 20 p.p.m. H2 rise (mean 85.8 p.p.m. plus or minus s.d. 44.3) at 2 hours. Similarly, two patients with normal jejunal lactase activity had no significant H2 production, whereas six patients with hypolactasia had more than a 20 p.p.m. rise in H2. Symptoms related to milk or lactose ingestion were found to be unreliable. End-expiratory sampling of breath H2 would seem to be a simple, non-invasive, and accurate method of diagnosing hypolactasia, which is also very acceptable to patients. This should make it a valuable tool both in diagnostic gastroenterology and in epidemiological surveys.
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PMID:Breath hydrogen as a diagnostic method for hypolactasia. 4 74

Rotaviruses are now regarded as important causes of diarrhoea in man, cattle, pigs, mice, and possibly other animals. Characteristically, disease occurs in newborn and young animals, and infection seems limited to the differentiated gut epithelial cells. The major surface polypeptide of the calf scours rotavirus is glycosylated, and highly purified beta-galactosidase (lactase) interacts with the virus in vitro causing removal of the outer shell of the capsid (uncoating). It is suggested that lactase present in the brush border of the intestinal epithelial cell performs a similar function in vivo by acting as a combined receptor and uncoating enzyme for the rotavirus. This hypothesis is consistent with the observations that rotaviruses seem to infect only gut epithelial cells, and that infant animals, whose lactase concentrations are generally higher than those of adult animals, seem more susceptible to rotavirus infections. Implications of the hypothesis include possible new approaches to laboratory cultivation of rotaviruses, which should be more successful in cells selected for surface lactase activity, and the suggestion that the epidemiology of human rotavirus infections may be influenced by the fact that different ethnic groups have different lactase levels (and hence lactose intolerance) in adulthood.
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PMID:Is lactase the receptor and uncoating enzyme for infantile enteritis (rota) viruses? 5 21

Twelve non-pathogenic bacteria and two yeast strains isolated from the duodenal aspirate or mucosa of five children with diarrhoea were tested for their ability to degrade non-human lactase in vitro. Both yeast strains and eleven of the bacterial strains significantly reduced lactase activity. A similar action on human lactase could be a cause of lactose intolerance.
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PMID:Lactase degradation by human enteric bacteria. 8 58

After bypass operation for obesity the remaining lactose-hydrolyzing capacity of the functioning shunt is very low, especially if the shunt is constructed from a shorter jejunal and a longer ileal segment. In most cases a temporary decrease in the lactase activity of the jejunal part of the shunt occurs during the first postoperative months. In the present study lactose provoked or aggravated diarrhoea and other symptoms in 20 of 33 shunt-operated patients, and 10 patients reported milk intolerance postoperatively. Oral glucose tolerance tests indicated that the lactase activity was rate limiting for lactose absorption postoperatively.
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PMID:Lactose malabsorption after bypass operation for obesity. 9 6

Low-lactose milk was produced by incubating cow's milk with yeast lactase. Sixteen lactose tolerant and 15 intolerant volunteers ingested 500 ml of the product twice daily for 1 month. During the testing period all subjects received on three occasions the same volume of unmodified milk in double-blind tests. Symptoms recorded throughout the study and for an additional 15 day base-line observation period were: diarrhea, abdominal pain and distention, flatulence, heartburn, and headache. Low-lactose milk acceptance was excellent. No significant differences were found between tolerants and intolerants during the base-line period and while ingesting low-lactose milk. By contrast, unmodified milk induced severe symptoms only in the intolerants. Availability of low-lactose milk and of its by-products allows consumption of greater volumes of this highly nutritious food by subjects with lactose intolerance with none or less symptoms compared to unmodified milk.
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PMID:Long-term acceptance of low-lactose milk. 11 42

Fifty hospital patients in Port Moresby (mean age 30 yr) without evidence of malnutrition or gastro-intestinal disease, who came from many parts of Papua New Guinea (P.N.G.), were given 50 g lactose orally after an overnight fast. In 49 blood glucose rise was less than 1.1 mmol 1(-1), indicating hypolactasia. Thirty-three gave a clear history of symptoms, usually diarrhoea, after lactose. Adult hypolactasia approaches 100% in P.N.G. There is no indication that the genetic structure of any part of the population of P,N.G. with regard to lactase has been influenced by genetic drift from peoples with persistence of lactase into adult life (PL).
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PMID:Intestinal lactase status of adults in Papua New Guinea. 43 66

To determine the validity of breath H2 measurements in detecting lactase deficiency, capillary blood glucose and breath H2 were measured after ingestion of 50 g lactose in 34 patients with abdominal symptoms or diarrhea. 18 patients had biopsy-proven lactase deficiency and 16 normal lactase activity. Blood glucose determination produced 2 false-positive results while breath H2 measurements provided 2 false-negative and 4 false-positive results.
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PMID:[Exhaled hydrogen test in the detection of lactase deficiency]. 44 12

Lactose tolerance tests were performed on 75 healthy Lebanese volunteers, 12 patients with "Mediterranean lymphoma" and 15 American and West European Caucasians. Small intestinal biopsies were done on 10 intolerant and five tolerant subjects for histological evaluation and lactase assay. Lactose malabsorption was present in 78% of the Lebanese subjects, in all patients with Mediterranean lymphoma and in five of the 15 Caucasians. Two of the five intolerant Caucasians had giardiasis. There was no difference in the prevalence rate among the various Lebanese groups nor among males and females. Symptoms occurred in 91% of the 58 intolerant Lebanese subjects: diarrhea in 71%, abdominal distension in 67%, and cramps in 48%. The increased prevalence of lactose intolerance with Mediterranean lymphoma is probably secondary to the pathological changes in the intestinal mucosa and protein depletion.
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PMID:Lactose intolerance in the Lebanese population and in "Mediterranean lymphoma". 48 18

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


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