Analysis of the DMPK gene CTG repeat in healthy Brazilians

Myotonic dystrophy (DM) is a neuromuscular disorder caused by the expansion of the cytosine-thymine-guanine (CTG) repeat of the myotonic dystrophy protein kinase gene (DMPK). This repeat is highly polymorphic in healthy individuals [(CTG)5-37], and it has been proposed that expanded CTG alleles originated from larger sized normal alleles [(CTG)19-37]. According to this hypothesis, a positive correlation should be expected between the frequency of these large-sized normal alleles and the prevalence of the disorder in a population. We determined the distribution of CTG alleles of the DMPK gene in 156 healthy Brazilians from Rio de Janeiro city. Our analyses of 312 chromosomes detected 20 different alleles ranging in size from 5 to 27 CTG repeats, with 24 alleles having more than 18 repeats (7.69 percent). This frequency of (CTG)3(19) alleles observed in our population suggests that the prevalence of DM in Rio de Janeiro should not be different from the prevalence in European populations.

Preliminary data on the performance of Aedes aegypti and Aedes albopictus immatures developing in water-filled tires in Rio de Janeiro

A monthly survey of Aedes aegypti and Aedes albopictus immatures in discarded tires at a site in metropolitan Rio de Janeiro showed that Ae. albopictus was much more abundant in the rainy season, but Ae. aegypti abundance showed a less clear seasonal pattern. Pupal masses for Ae. albopictus showed a seasonal trend. In contrast, Ae. aegypti pupae did not show any clear trend in weight. Large Ae. albopictus pupae were found in the warmer months, when water volume was higher, pH lower, and larval abundance lower. Further studies should be carried out to assess how seasonal variations in body size may impact vector competence of these species in Brazil.

Rastreamento da fibrose cística usando-se a análise combinada do teste de IRT neonatal e o estudo molecular da mutaçäo deltaF508 / Cystic fibrosis screening by two-tiered newborn IRT assay and deltaF508 mutation molecular analysis

Um total de 117 cartöes de rastreamento neonatal foi selecionado anonimamente para a avaliaçäo de fibrose cística (FC) pela análise da mutaçäo deltaF508 usando-se a técnica da reaçäo em cadeia da polimerase (PCR), seguida de eletroforese em gel de poliacrilamida (Page) e pela quantificaçäo da imunotripsina reativa (IRT, Delfia). Uma concentraçäo de IRT menor que 140ng/ml foi encontrada em 116 recém-nascidos. Entre estes foi detectado um heterozigoto deltaF508 com uma concentraçäo de IRT de 4,44ng/ml. Um dos 117 recém-nascidos era homozigoto näo-deltaF508 e apresentava uma IRT anormal de 410,7ng/ml. A média da concentraçäo da IRT diferia significativamente conforme este recém-nascido com IRT alterada era incluído ou excluído da amostragem populacional (n = 117, média = 8,207 ± 38,101; n = 116, média = 4,737 ± 6,597, respectivamente). Outra amostra de oito recém-nascidos, previamente rastreados pelo teste de IRT e com níveis elevados do analito, foi testada para a mutaçäo deltaF508. Em cinco deles a mutaçäo deltaF508 foi encontrada em um ou em ambos os cromossomos, correspondendo a 62,25 por cento dos recém-nascidos. De acordo com os resultados obtidos com triagem neonatal pela análise combinada IRT/DNA, pode-se concluir que o método só será eficiente se: a) forem excluídos os fatores que determinam os falso-positivos ou falso-negativos; e b) a detecçäo de outras mutações forem incluídas na análise dos resultados duvidosos

Seroprevalence of Hepatitis B virus infection among an afro-descendant community in Brazil

Furnas dos Dionísios is an Afro-Brazilian black community whose descendants were mainly fugitive slaves that established themselves in the State of Mato Grosso do Sul (MS), Brazil. The population is comprised mainly of low socioeconomic individuals who are engaged in agricultural activities. The objective of this study was to investigate the prevalence of hepatitis B (HB) and its correlation with epidemiological data obtained from the community. The studied population totaled 260 individuals with ages varying from 1 to 79 years (median 20). One hundred thirty-three (51.2 percent) were females and 127 (48.8 percent) were males. A high prevalence for anti-HBc was observed (42.7 percent), with present infection detected in 9.2 percent of the subjects who were also HB surface antigens (HBs Ag) positive; 27.3 percent were anti-HBc and anti-HBs reactive, and 6.2 percent had anti-HBc as only marker. The prevalence for anti-HBc was proportional to age, reaching its highest peak in age categories greater than 50. No serological marker was detected in children under the age of 2 years, however anti-HBc was present in 12 subjects with ages between 2 and 14 years, of these 8 (7.4 percent) were HBsAg positive. Among individuals over the age of 15 years, 99 were anti-HBc reactive, of these 16 (10.5 percent) were also HBsAg positive, thus suggesting an increased prevalence of HBV carriers among children and adolescents. The risk factors observed in this community that were significantly associated with anti-HBc positivity were age (over 20 years) and having an anti-HBc positive mother. Both HBeAg and anti-HBe were detected in 44.4 percent of the samples tested. HBsAg subtypes found in the studied population were adw2 (77.7 percent) and ayw2 (23.3 percent). While intrafamilial transmission was most likely responsible for HBV infection among children, other routes such as sexual contact might be considered for individuals with ages over 15 years

Studies on populations of Lutzomyia longipalpis (Lutz & Neiva, 1912) (Diptera: Psychodidae: Phlebotominae) in Brazil

Studies were performed on five Brazilian populations of Lutzomyia longipalpis: Salvaterra (PA), São José do Ribamar (MA), Canindé (CE), Natal (RN) and Gruta da Lapinha, Lagoa Santa (MG). No morphological differences were observed that could distinguish between these populations. Homogeneity tests showed that the allopatric populations display a certain heterogeneity and that the sympatric populations, with different patterns of spots, are homogeneous. The Student-Newman-Keuls test, represented by Euler-Venn diagrams, showed a disjunction between the populations from the north/northeast and the one from Gruta da Lapinha. Genetic distances between the four populations (excluding the Canindé population) were within the range of intrapopulational differences. The Gruta da Lapinha population displayed a heterozygotic deficiency that could be a consequence of high levels of inbreeding due to cryptic habits of living in a small cave. These results do not favor the hypothesis of a L. longipalpis species complex in Brazil, and the species should be considered high polymorphic.