ABSTRACT
PURPOSE: To analyze the usefulness of Quick Lactose Intolerance Test in relation to the genetic test based on LCT-13910C>T genotypes, previously validated for clinical practice, for primary hypolactasia/lactase-persistence diagnosis. METHODS: Thirty-two dyspeptic patients that underwent upper gastrointestinal endoscopy entered the study. Two postbulbar duodenal biopsies were taken for the Quick test, and gastric antral biopsy for DNA extraction and LCT-13910C>T polymorphism analysis. DNA was also extracted from biopsies after being used in the Quick Test that was kept frozen until extraction. RESULTS: Nine patients with lactase-persistence genotype (LCT-13910CT or LCT-13910TT) had normolactasia, eleven patients with hypolactasia genotype (LCT-13910CC) had severe hypolactasia, and among twelve with mild hypolactasia, except for one that had LCT-13910CT genotype, all the others had hypolactasia genotype. The agreement between genetic test and quick test was high (p<0.0001; Kappa Index 0.92). Most of the patients that reported symptoms with lactose-containing food ingestion had severe hypolactasia (p<0.05). Amplification with good quality PCR product was also obtained with DNA extracted from biopsies previously used in the Quick Test; thus, for the future studies antral gastric biopsies for genetic test would be unnecessary. CONCLUSION: Quick test is highly sensitive and specific for hypolactasia diagnosis and indicated those patients with symptoms of lactose intolerance.
OBJETIVO: Analisar a aplicabilidade do Teste Quick de Intolerância à Lactose em relação ao teste genético baseado nos genótipos LCT-13910C>T, previamente validado para a prática clínica, para diagnóstico de má digestão primária de lactose/digestão de lactose. MÉTODOS: Trinta e dois pacientes dispépticos submetidos à endoscopia digestiva entraram no estudo. Duas biópsias duodenais pós-bulbares foram empregadas no Teste Quick, e biópsia do antro gástrico para extração de DNA e análise do polimorfismo LCT-13910C>T. DNA também foi extraído de biópsias depois de terem sido usadas no teste Quick, e conservadas congeladas. RESULTADOS: Nove pacientes com genótipo de lactase persistente (LCT-13910CT ou LCT-13910TT) tinham normolactasia, onze pacientes com genótipo de hipolactasia (LCT-13910CC) tinham hipolactasia severa, e entre doze com hipolactasia leve, com exceção de uma que tinha genótipo LCT-13910CT, todos os demais tinham genótipo de hipolactasia. A concordância entre o teste genético e o Quick Teste foi alta (p<0,0001; Índice Kappa=0,92). A maioria dos pacientes que relataram sintomas com ingestão de alimentos com lactose tinham hipolactasia severa (p<0,05). Amplificação com produto de PCR foi obtido com DNA extraído das biópsias usadas no teste Quick; portanto, nos trabalhos futuros seria desnecessário coletar biópsia do antro gástrico para o teste genético. CONCLUSÃO: O Teste Quick é altamente sensível e específico para diagnóstico de hipolactasia e indicou aqueles pacientes com sintomas de intolerância à lactose.
Subject(s)
Adult , Aged , Female , Humans , Male , Middle Aged , Genetic Testing , Lactose Intolerance/diagnosis , Lactose Tolerance Test/methods , Biopsy , Duodenum/pathology , Dyspepsia/pathology , Endoscopes, Gastrointestinal , Genotype , Lactase/deficiency , Lactose Intolerance/genetics , Lactose/genetics , Polymerase Chain Reaction , Polymorphism, Single Nucleotide , Prothrombin Time , Retrospective Studies , Surveys and QuestionnairesABSTRACT
Lactase-phlorizin hydrolase (LPH), a membrane-bound glycoprotein present in the luminal surface of enterocytes in the intestine is responsible for lactose intolerance, a phenomenon prevalent in humans worldwide. In the rodent intestine, the post-natal development of the LPH follows a specific pattern, such that the enzyme levels are high in the peri-natal period, but declines considerably upon maturation. The observed maturational decline in the LPH activity is very similar to adult-type hypolactasia observed in humans. Majority of the studies have been carried out using animal models or cell lines and a number of hypotheses have been put forward to explain the maturational decline of lactase activity such as: (a) decreased amount of lactase protein, (b) defect in post-translational modification of precursor lactase to the mature enzyme, and (c) synthesis of an inactive, high molecular weight lactase with altered glycosylation, however, the precise underlying mechanism of adult-type hypolactasia remains undefined. The present review describes the recent developments in understanding the regulation of lactase expression and the possible mechanism of adult-type hypolactasia, as a cause of lactose intolerance.
Subject(s)
Animals , Gene Expression Regulation, Enzymologic , Glycosylation , Lactase-Phlorizin Hydrolase/chemistry , Humans , Lactase/biosynthesis , Lactose/genetics , Lactose Intolerance/etiology , Polymorphism, GeneticABSTRACT
Cepas de Candida albicans, mantidas em meios de cultura usuais, originaram colônias que em testes de assimilaçäo de fontes de carbono mostraram-se lac+ mal-. Esferosplastos obtidos a partir de células normais, lac- mal+, foram submetidos à fusäo e produziram apenas células lac+ mal+. Após reduçäo na ploidia,essas células deram origem a colônias lac- mal+ (82 por cento), lac- mal (13,3 por cento) e lac+ mal+ (4,4 por cento). Discute-se neste trabalho, ploidia dos produtos de fusäo, ocorrência de heterocariose nesses produtos e a perda de cromossomos durante a segregaçäo