Disaccharidase activities in dyspeptic children: biochemical and molecular investigations of maltase-glucoamylase activity.
BACKGROUND
Maltase-glucoamylase enzyme plays an important role in starch digestion. Glucoamylase deficiency is reported to cause chronic diarrhea in infants, but its role in dyspeptic children is unknown.


METHODS
Glucoamylase and other disaccharidase specific activities were assayed from duodenal biopsy specimens in 44 children aged 0.5-18 years (mean, 10 +/- 5 years) undergoing endoscopy to evaluate dyspeptic symptoms. All subjects had normal duodenal histology. Intestinal organ culture was used to evaluate synthesis and processing of maltase-glucoamylase. Sequencing of the maltase-glucoamylase coding region was performed in subjects with low activity or variation of isoform in organ culture.


RESULTS
Twenty-two of the dyspeptic children had one or more disaccharidases with low specific activity. Twelve subjects (28%) had low activity of glucoamylase. Eight subjects had low activities of glucoamylase, sucrase, and lactase. Low glucoamylase activity was not correlated with the isoform phenotype of maltase-glucoamylase as described by metabolic labeling and sodium dodecyl sulfate electrophoresis. Novel nucleotide changes were not detected in one subject with low glucoamylase activity or in two subjects with variant isoforms of maltase-glucoamylase peptides.


CONCLUSIONS
Twelve of 44 dyspeptic children had low specific activity of duodenal maltase-glucoamylase. Eight of these children had low specific activity of all measured disaccharidases.
Karnsakul
Wikrom
W
USDA Children's Nutrition Research Center, Baylor College of Medicine, and Texas Children's Hospital, Houston 77030, USA.
Luginbuehl
Ursula
U
Hahn
Dagmar
D
Sterchi
Erwin
E
Avery
Stephen
S
Sen
Partha
P
Swallow
Dallas
D
Nichols
Buford
B
D001706:Biopsy; D018076:DNA, Complementary / Q000032:analysis; D004186:Disaccharidases / Q000172:deficiency / Q000378:metabolism*; D004386:Duodenum / Q000201:enzymology / Q000473:pathology; D004415:Dyspepsia / Q000201:enzymology*; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D005959:Glucosidases / Q000172:deficiency / Q000378:metabolism; D006801:Humans; D007223:Infant; D007413:Intestinal Mucosa / Q000201:enzymology* / Q000473:pathology; D007527:Isoenzymes; D043322:Lactase; D008297:Male; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013393:Sucrase / Q000172:deficiency / Q000378:metabolism; D000520:alpha-Glucosidases / Q000172:deficiency / Q000378:metabolism*; D001616:beta-Galactosidase / Q000172:deficiency / Q000378:metabolism
D018076:DNA, Complementary; D007527:Isoenzymes; D004186:Disaccharidases; D005959:Glucosidases; D043322:Lactase; D000520:alpha-Glucosidases; D001616:beta-Galactosidase; D013393:Sucrase