Affiliation:
1. Departamento de Bioquı́mica and Instituto de Investigaciones Biomédicas Alberto Sols Universidad Autónoma de Madrid-Consejo Superior de Investigaciones Cientı́ficas, Facultad de Medicina de la Universidad Autónoma de Madrid, Madrid, Spain
2. Instituto de Quı́mica Orgánica General, Consejo Superior de Investigaciones Cientı́ficas, Madrid, Spain
Abstract
Abstract
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 to suckling rats of different ages. d-Xylose was measured colorimetrically by the phloroglucinol reaction in urine and plasma. Lactase activity was determined in extracts of small intestine mucosa with lactose, galactosylxyloses, and phlorizin as substrates.
Results: d-Xylose appeared in the urine in a dose-dependent manner after ingestion of any of the 3 galactosylxylose disaccharides. Correlation between d-xylose elimination and intestinal lactase activity was highest with 4-galactosylxylose (r = 0.97; n = 24), lower with 2-galactosylxylose (r = 0.89; n = 24), and lowest with 3-galactosylxylose (r = 0.34; n = 23). The kinetic properties of intestinal lactase accounted for these differences. d-Xylose concentration in plasma after administration of 4-galactosylxylose also correlated with lactase activity (r = 0.93; n = 33).
Conclusions: 4-Galactosylxylose is the most suitable compound for the evaluation of lactase activity in vivo. Measurement of the derived d-xylose in either urine or blood gives an estimate of the total lactose digestive capacity of the small intestine. The optimized method holds promise for development of a simple, low-cost, and reliable new test for the noninvasive diagnosis of hypolactasia.
Publisher
Oxford University Press (OUP)
Subject
Biochemistry (medical),Clinical Biochemistry
Reference36 articles.
1. Semenza G, Auricchio S, Mantei N. Small-intestinal disaccharidases [Review]. Scriber CR Beaudet AL Sly WS Valle D Childs B Kinzler KWet al eds. The metabolic and molecular bases of inherited disease2001;Vol. 1:1623-1650 McGraw-Hill New York. .
2. Villako K, Maaroos H. Clinical picture of hypolactasia and lactose intolerance [Review]. Scand J Gastroenterol1994;202(Suppl 29):36-54.
3. Swallow DM, Hollox EJ. Genetic polymorphism of intestinal lactase activity in adult humans [Review]. Scriber CR Beaudet AL Sly WS Valle D Childs B Kinzler KWet al eds. The metabolic and molecular bases of inherited disease2001;Vol. 1:1651-1663 McGraw-Hill New York. .
4. Sahi T. Genetics and epidemiology of adult-type hypolactasia [Review]. Scand J Gastroenterol1994;202(Suppl 29):7-20.
5. Newcomer AD, McGill DB, Thomas PJ, Hofmann AF. Prospective comparison of indirect methods for detecting lactase deficiency. N Engl J Med1975;293:1232-1236.
Cited by
14 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献