Aprendizagem baseada em casos clínicos no ensino de genética para medicina / Learning based on clinical cases in the teaching of genetics for medicine

Resumo Introdução: A necessidade premente de formar médicos autônomos e proativos implica novas abordagens didáticas e formas de mediar o conteúdo. Nesse contexto, a utilização de métodos ativos de ensino e aprendizagem pode incrementar o perfil do novo profissional. A Aprendizagem Baseada em Casos (ABC) é uma estratégia fundamentada na capacidade de o estudante relacionar teoria e prática com autonomia e tomada de decisão. A disciplina de genética aborda conteúdos que podem parecer distantes do cotidiano e da prática profissional futura, e, por isso, a necessidade de utilizar estratégias de ensino que facilitem a compreensão da aplicação desse conhecimento na prática médica. Objetivo: O presente trabalho teve por objetivo avaliar a ABC como abordagem pedagógica no processo de ensino-aprendizagem de genética para o curso de Medicina de uma instituição pública. Método: Aplicou-se um protocolo de método ativo composto por nove casos clínicos a 46 estudantes de Medicina da Universidade de Brasília que, posteriormente, foram divididos em nove grupos. Por meio de questionários, avaliaram-se o desempenho e as percepções em relação ao método. Os resultados quantitativos foram analisados por meio do teste t de Student. Resultado: O rendimento do trabalho em grupo foi estatisticamente maior em oito dos nove casos em comparação ao trabalho individual. A atividade foi considerada boa ou muito boa por 76% dos estudantes, e 90% mencionaram que houve aumento da motivação. Além disso, 71,4% destes demonstraram interesse em estudar mais sobre o assunto após a aula, 20% se consideraram capazes de ensinar o assunto a outras pessoas, e 42% avaliaram que acertariam todas ou a maioria das questões caso fossem submetidos a uma nova avaliação. Com relação ao trabalho em equipe, 38% relataram se sentir mais motivados. Por fim, 86% consideraram relevante ou muito relevante a discussão de casos clínicos para a formação profissional. Conclusão: Os resultados demostraram sucesso no uso do método ABC na abordagem de genética, porém apontaram que há dificuldades na utilização de métodos de ensino alternativos à aula expositiva. Apesar disso, fica explícito que a estratégia adotada pode levar à mobilização de conhecimentos prévios em situações da prática profissional.

Abstract Introduction: The pressing need to train autonomous and proactive professionals demands new ways of mediating content. In this context, the use of active teaching and learning methods can improve the profile of the new professional. Case-Based Learning (CBL) is a strategy based on the student's ability to relate theory and practice, with autonomy and decision-making. The discipline of Genetics addresses contents that may seem distant from everyday life and future professional practice, so it is necessary to use teaching strategies that facilitate the understanding of the application of this knowledge in medical practice. Objective: This study aimed to evaluate the CBL as a pedagogical approach in the teaching-learning process of Genetics for Medicine courses in a public institution. Methods: An active methodology protocol that consisted of nine clinical cases was applied to 46 medical students from Universidade de Brasília, who were later divided into nine groups. The performance and perceptions regarding the methodology were evaluated by questionnaires. Quantitative results were analyzed using Student's t test. Results: The performance of group work was statistically higher in 8 of 9 cases compared to individual work. Most students considered the activity good or very good (76%), but approximately half reported no increase in motivation. Moreover, 71.4% felt motivated to learn more about the subject after class and 20% considered they were able to teach the subject to others and 42% assessed they would get all or most of the questions correct if they were submitted to a new assessment. Regarding teamwork, 38% reported feeling more motivated. Finally, 86% considered the discussion of clinical cases relevant or very relevant for professional training. Final considerations: The results show, in general, success in the use of CBL on the study of genetic diseases but point out that there are difficulties in the use of alternative teaching methods to the lecture. Despite this, it is clear that learning based on clinical cases can lead to the mobilization of previous knowledge in situations of professional practice.

Superoxide dismutase, catalase, glutathione peroxidase and gluthatione S-transferases M1 and T1 gene polymorphisms in three Brazilian population groups

Antioxidants such as superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX1) reduce the oxidation rates in the organism. Gluthatione S-transferases (GSTs) play a vital role in phase 2 of biotransformation of many substances. Variation in the expression of these enzymes suggests individual differences for the degree of antioxidant protection and geographical differences in the distribution of these variants. We described the distribution frequency of CAT (21A/T), SOD2 (Ala9Val), GPX1 (Pro198Leu), GSTM1 and GSTT1 polymorphisms in three Brazilian population groups: Kayabi Amerindians (n = 60), Kalunga Afro-descendants (n = 72), and an urban mixed population from Federal District (n = 162). Frequencies of the variants observed in Kalunga (18 percent to 58 percent) and Federal District (33 percent to 63 percent) were similar to those observed in Euro and Afro-descendants, while in Kayabi (3 percent to 68 percent), depending on the marker, frequencies were similar to the ones found in different ethnic groups. Except for SOD2 in all population groups studied here, and for GPX1 in Kalunga, the genotypic distributions were in accordance with Hardy-Weinberg Equilibrium. These data can clarify the contribution of different ethnicities in the formation of mixed populations, such as that of Brazil. Moreover, outcomes will be valuable resources for future functional studies and for genetic studies in specific populations. If these studies are designed to comprehensively explore the role of these genetic polymorphisms in the etiology of human diseases they may help to prevent inconsistent genotype-phenotype associations in pharmacogenetic studies.

Beta-globin haplotypes in normal and hemoglobinopathic individuals from Reconcavo Baiano, State of Bahia, Brazil

Five restriction site polymorphisms in the Beta-globin gene cluster (HincII-5'épsilon, HindIII-Ggama, HindIII-Agama, HincII-PsiBeta1 and HincII-3'PsiBeta1) were analyzed in three populations (n = 114) from Reconcavo Baiano, State of Bahia, Brazil. The groups included two urban populations from the towns of Cachoeira and Maragojipe and one rural Afro-descendant population, known as the "quilombo community", from Cachoeira municipality. The number of haplotypes found in the populations ranged from 10 to 13, which indicated higher diversity than in the parental populations. The haplotypes 2 (+----), 3 (----+), 4 (-+--+) and 6 (-++-+) on the BetaA chromosomes were the most common, and two haplotypes, 9 (-++++) and 14 (++--+), were found exclusively in the Maragojipe population. The other haplotypes (1, 5, 9, 11, 12, 13, 14 and 16) had lower frequencies. Restriction site analysis and the derived haplotypes indicated homogeneity among the populations. Thirty-two individuals with hemoglobinopathies (17 sickle cell disease, 12 HbSC disease and 3 HbCC disease) were also analyzed. The haplotype frequencies of these patients differed significantly from those of the general population. In the sickle cell disease subgroup, the predominant haplotypes were BEN (Benin) and CAR (Central African Republic), with frequencies of 52.9 percent and 32.4 percent, respectively. The high frequency of the BEN haplotype agreed with the historical origin of the afro-descendant population in the state of Bahia. However, this frequency differed from that of Salvador, the state capital, where the CAR and BEN haplotypes have similar frequencies, probably as a consequence of domestic slave trade and subsequent internal migrations to other regions of Brazil.

Analysis of genetic susceptibility to mercury contamination evaluated through molecular biomarkers in at-risk Amazon Amerindian populations

We investigated Individual differences in susceptibility to methylmercury (MeHg) contamination and its relationship with polymorphisms of the detoxifying enzyme glutathione S-transferase (GST). In Brazil, some Amerindian tribes from the Amazon region have an increased level of mercury in their hair. Samples of hair and blood were taken from inhabitants of two villages in the Kayabi and Munduruku Amerindian communities to investigate mercury levels in association with genetic polymorphism of GSTs. Other molecular biological markers were also studied, such as hemoglobin, haptoglobin and glucose 6-phosphate dehydrogenase (G-6-PDH). Higher levels of mercury contamination were found in the Kayabi villagers, who had a null genotype (GSTM1 0/0, also denominated GSTM1 null) frequency of 26%, than in the Munduruku villagers, for which the null genotype frequency was 0%. Individuals with the GSTM1 null phenotype had higher concentrations of mercury in their hair than individuals with GSTM1+/+ phenotypes (F = 21.51, p < 0.0001). No association with other markers studied was observed. This study suggests that GSTM1 may be involved in the biotransformation of mercury in humans

Distribution of glutathione S-transferase GSTM1 and GSTT1 null phenotypes in Brazilian Amerindians

The distribution of glutathione S-transferase (GST) GSTM1 and GSTT1 null phenotype frequencies in two Brazilian Amerindian tribes, the Munduruku tribe from Missão Cururu village (79 individuals) and the Kayabi tribe (41 individuals), was analyzed by polymerase chain reaction (PCR) amplification. The GST null phenotype frequencies for the Munduruku sample were 0 percent for GSTM1 and 27 percent for GSTT1 while for the Kayabi sample the null phenotype frequencies were 27 percent for GSTM1 and 29 percent for GSTT1. This is the first report of the absence of the GSTM1 null phenotype in any ethnic group.

Genotoxicity evaluation of domestic sewage in a municipal wastewater treatment plant

An evaluation of the genotoxicity of domestic sewage was carried out in a municipal wastewater treatment plant. The study was carried out using Allium cepa root tip cells through cytological parameters such as aberrant cells in anaphase-telophase and the mitotic index, and the fish species Oreochromis niloticus and Tilapia rendalli, through the index of micronuclei in peripheral erythrocytes. In the Allium test, each of the four stages of the wasterwater treatment routine was analyzed, i.e., crude sewage, primary effluent, secondary effluent, and tertiary effluent. O. niloticus and T. rendalli specimens were maintained in an aquarium continuously receiving the final effluent, in an open system, before being discharged into Lake Paranoá. For micronuclei analysis, blood samples were drawn after 7, 21, 60, 102 and 142 days, respectively, in controlled conditions. The numbers of aberrant cells found in the Allium test did not differ among the four stages tested, nor when compared with the control. At all stages, the most concentrated sample was more toxic than the respective diluted samples, as demonstrated by the decreased mitotic index. Different sampling of the same group of fish revealed no increase in the micronuclei frequency, regardless of the period of exposure. A correlation between long-term exposure and micronuclei induction was not found either.

CCR5D32 mutation in three Brazilian populations of predominantly Sub-Saharan African ancestry

This study reports the frequencies of the CCR5D32 mutation of the beta-chemokine 5 gene and discusses the possible effects of past and recent gene flow in three quilombo remnants (Brazilians communities with anthropological African ancestry whose ancestors were escaped slaves): Rio das Rãs, Mocambo, and São Gonçalo in the northeastern region of Brazil. The CCR5D32 allele frequency of the Mocambo population was significantly higher (5.6 percent) than that found in the Rio das Rãs (1 percent) and São Gonçalo (0.9 percent) populations. These differences may reflect different proportions of parental populations in the founders individuals, a founder-effect and/or different histories of inter-ethnic contact. The frequency of the CCR5D32 allele in the Mocambo sample is similar to that found in those urban Brazilian populations which have a large amount of European genetic input, indicating a European contribution to the gene pool of this population and suggesting that, perhaps since its foundation, Mocambo has had a high level of admixture or experienced a founder-effect.