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Biomedical subjects

A I Lopes

Publications and source records attributed to A I Lopes.

7 recordsLinked to original sources
PubMed2006

Mucosal lymphocyte subsets and HLA-DR antigen expression in paediatric Helicobacter pylori-associated gastritis.

Paediatric studies may provide important insights into the immunopathology of Helicobacter pylori-associated gastritis, as mucosal changes reflect different stages of the immunoinflammatory response. We characterized, by quantitative immunohistochemistry, gastric mucosal lymphocyte phenotype and HLA-DR antigen expression and evaluated correlation with histopathology, in H. pylori-infected (Hp+ve) and uninfected children (Hp-ve). In the infected group, lamina propria CD3+ and IgA plasmocyte cell numbers were significantly higher and a trend for predominance of CD8+ over CD4+ was observed both in epithelium and lamina propria. A correlation of inflammation score with lamina propria CD3+ and CD4+ cell numbers and of CD45RO+ T lymphocytes with density of colonization was observed. The proportion of epithelial cells expressing HLA-DR antigen was significantly higher in the Hp+ve group and furthermore, glandular HLA-DR expression correlated with lamina propria CD3+ cell numbers, emphasizing the potential role of epithelial cells as antigen-presenting cells at this stage of infection.

Adolescent↗
PubMed2003

Helicobacter pylori virulence genotypes in Portuguese children and adults with gastroduodenal pathology.

The aim of this study was to evaluate the prevalence of virulence genotypes, namely cagA, vacA and babA2, of Helicobacter pylori strains isolated from Portuguese adults and children presenting gastroduodenal pathology. One hundred thirty-six strains were studied, 82 isolated from adult patients (50 with nonulcerative gastritis and 32 with active peptic ulcer) and 58 isolated from children (54 with nonulcerative gastritis and 4 with duodenal ulcer). Genotyping of cagA, vacA and babA2 was assessed by polymerase chain reaction. Overall, Helicobacter pylori strains carrying more virulent genotypes were much more prevalent in adults than in children, particularly the type I ( vacAs1- and cagA-positive) and the triple-positive ( vacAs1-, cagA- and babA2-positive) strains ( P<0.001). A subpopulation of adults and children with nonulcerative gastritis was also studied, and differences in the prevalence of virulent genotypes were observed, either for individual genotypes ( P=0.017 for cagA, P=0.010 for vacAs1) or in combinations, i.e. the type I genotype ( P=0.005) and the triple-positive strains ( P=0.031). There was no difference between the two populations in the distribution of babA2 and m1/m2 genotypes. Considering the cohort effect in the epidemiology of Helicobacter pylori infection, these results suggest that different strains might circulate during different periods of time, or that, after infection in childhood, individual strains will undergo changes during the course of infection.

Adult↗
PubMed2000

Features and trends in Helicobacter pylori antibiotic resistance in Lisbon area, Portugal (1990-1999).

The features of Helicobacter pylori antibiotic resistance in Lisbon from 1990 to 1999 were studied. Overall resistance rates to amoxycillin, tetracycline, metronidazole, clarithromycin and ciprofloxacin were 0, 0, 30.6, 19.0 and 9.6%, respectively. The incidence of resistance to clarithromycin was much higher in isolates from children (44.8%) than adults (14.6%). For metronidazole, the contrary was observed (children: 19.0%, adults: 32.3%). Ciprofloxacin-resistant isolates were all from adult patients. Concerning the adult population, the resistance rate to metronidazole showed a slight increase during the decade, while for clarithromycin and ciprofloxacin a significant increase was observed (4.6 to 22.0% and 0 to 20.9%, respectively).

Adolescent↗
PubMed1998

[Hereditary fructose intolerance].

Hereditary fructose intolerance (HFI) is a rare autosomal recessive, metabolic disorder, that results from a deficiency of aldolase B (fructose-biphosphate aldolase) in the liver, kidney and intestine. Recent molecular studies have identified the mutation A149P in most European patients. We describe the first case of HFI with molecular analysis in a Portuguese child, presenting the same mutation of the aldolase B gene. The role of molecular studies in the diagnosis of HFI risk patients and their families is emphasized.

Alleles↗
PubMed1995

[A methodology for the diagnosis and follow-up of the evolution of acute hepatitis in childhood. The Working Group of the Section of Pediatric Gastroenterology and Nutrition of the Portuguese Pediatrics Society].

The Working Group of the Section of Paediatric Gastroenterology and Nutrition of the Portuguese Society of Paediatrics established a protocol for the investigation of children with acute hepatitis. The main purpose of this proposal is to allow appropriate etiologic investigations and avoid unnecessary tests that are expensive and do not add relevant information for the correct follow-up of these patients.

Acute Disease↗
PubMedDate not supplied

IgG subclasses serum concentrations in a population of children with Down syndrome: comparative study with siblings and general population.

Serum total IgG and subclasses were determined in three different groups of children: with Down syndrome, their siblings and general pediatric population. Several cases of IgG2 and IgG4 deficiency were identified, predominantly in children with Down syndrome. The differences, considering three age groups, were statistically significant for both groups in relation to the general population group, with an increase of IgG1 and IgG3 and a decrease in serum concentrations of IgG2 and IgG4. Down syndrome children and their siblings tend o have a similar variation of the IgG4 serum concentration levels (P < 0.05). The mechanisms of this concordance are not well understood. The results point out that an adequate strategy to improve the immune status of Down syndrome children could have a positive manifestation in the immune profile of their brothers.

Adolescent↗