Two phenotypes exist in the human population with regard to expression of lactase in adults. Lactase non-persistence (adult-type hypolactasia and lactose intolerance) is characterized by a decline in the expression of lactase-phlorizin hydrolase (LPH) after weaning. In contrast, lactase-persistent individuals have a high LPH throughout their lifespan. Lactase persistence and non-persistence are...

Carbohydrates are hydrolyzed in the intestinal lumen by specific enzymes to monosaccharides before transport across the brush border membrane of epithelial cells into the cell interior. The enzymes implicated in the digestion of carbohydrates in the intestinal lumen are membrane-bound glycoproteins that are expressed at the apical domain of the enterocytes. Absent or reduced activity of one of ...

OBJECTIVE The aim of this study was to evaluate the suspicion of cow's-milk allergy in infants with unspecific gastrointestinal (GI) symptoms using the double-blind, placebo-controlled food challenge. METHODS A prospective cohort study, which recruited 57 consecutive children with gastrointestinally manifested symptoms suspected of cow's-milk allergy. All patients underwent a 5-day double-bli...

The intestinal brush-border enzyme lactase splits lactose into its component monosaccharides, glucose and galactose. Relative deficiency of the enzyme during adulthood is a common condition worldwide and is frequently associated with symptoms of lactose intolerance. We studied the synthesis and processing of lactase in normal and adult hypolactasic subjects using human intestinal explants in or...

In disease states of the small intestine--for example, gluten-sensitive enteropathy--there is an increased permeability to large molecules. This increased permeability extends to polar molecules of intermediate size such as disaccharides, whereas small polar molecules are malabsorbed. A recently-developed oral test, based on the simultaneous administration of two test substances, cellobiose (a ...

The C/T-13910 mutation is the major factor responsible for the persistence of the lactase-phlorizin hydrolase (LCT) gene expression. Mutation G/A-22018 appears to be only in co-segregation with C/T-13910. The objective of the present study was to assess the presence of these two mutations in Brazilian individuals with and without lactose malabsorption diagnosed by the hydrogen breath test (HBT)...

Most people are born with the ability to digest lactose. Approximately 75% of the general population loses this ability, to some extent, going into adulthood (adult hypolactasia), while others retain such ability. The aim of the present study was to determine the prevalence of lactose intolerance, and its correlation with gastrointestinal symptoms, in primary school children aged 6-12 years in ...

Lactose malabsorption is a very common condition characterized by intestinal lactase deficiency. Primary lactose malabsorption is an inherited deficit present in the majority of the world's population, while secondary hypolactasia can be the consequence of an intestinal disease. The presence of malabsorbed lactose in the colonic lumen causes gastrointestinal symptoms. The condition is known as ...

BACKGROUND Urinary excretion of D-xylose by suckling rats after ingestion of a mixture of 4-, 3-, and 2-galactosylxyloses reflects lactase activity in vivo. We aimed to select the most convenient of these disaccharides for detecting changes of the enzyme activity in vivo and to optimize the method. METHODS 4-, 3-, and 2-galactosylxyloses were synthesized and purified, then orally administered...

Diarrhoea is a common sequel to vagotomy and pyloroplasty but its cause is unknown. One of our patients who developed this complication had an abnormal lactose barium meal and responded well to a lactose-free diet. This led us to make a systematic study of disaccharidase activity in the small intestine in patients with diarrhoea following vagotomy and pyloroplasty. The small-intestinal disaccha...