A discrepancy in the ABO blood groups between a newborn child and her parents was identified. Serological and DNA investigative techniques were performed. A weak variant of B (B(w)) was detected on the erythrocytes of the child, her grandmother and great-uncle. Adsorption-elution studies showed that their erythrocytes adsorb and yield anti-B on elution. The B(w) antigenic strength of the A(1)B(w) cells of her mother and maternal aunt was reduced when compared to that of the A(2)B(w) from another family member. Only one of 15 different anti-B sera agglutinated the A(1)B(w) erythrocytes. Agglutinin anti-B that reacted strongly with normal B erythrocytes and did not agglutinate the B(w) cells, was found in the sera of the A(1)B(w) individuals. The B(w) serum glycosyltransferase could not convert O cells into B cells and no B substance was found in saliva. All family members with the B(w)/AB(w) phenotypes were heterozygous for a B allele and DNA sequencing revealed a novel missense mutation in exon 7 of the B allele (556A > G), resulting in M186V. This substitution changes a highly conserved region of the enzyme, proposed to be a disordered loop near the enzyme cleft, and is expected to diminish the enzyme's activity, leading to this B(w) phenotype.

Objective/Aim: The aim of this study is to describe the distribution of the platelet blood group A antigenicity in Euro-Brazilians (EUBs) and Afro-Brazilians (AFBs).Background: A small but significant proportion of individuals express high levels of A or B antigen on their platelets corresponding to the erythrocyte ABO group. The mechanism of increased antigen expression has not been elucidated.Material/Methods: A cohort of 241 blood group A donors was analysed by flow cytometry. Although mean fluorescence intensity (MFI) is a typical continuous variable, platelets were screened and divided into two categories: low expressers (LEs) and high expressers (HEs). A three-generation family was investigated looking for an inheritance mechanism.Results: The prevalence of the HE platelet phenotype among group A1 donors was 2%. The mean of MFI on platelets of A1 subgroup of EUBs differs from that of AFBs (P = 0·0115), whereas the frequency of the HE phenotype was similar between them (P = 0·5251). A significant difference was found between sexes (P = 0·0039). Whereas the serum glycosyltransferase from HE family members converted significantly more H antigen on group O erythrocytes into A antigens compared with that in LE serum, their ABO, FUT1 and FUT2 genes were consensus. The theoretically favourable, transcriptionally four-repeat ABO enhancer was not observed.Conclusion: The occurrence of HE in several members suggests familial aggregation. Indeed, in repeated measures, stability of the MFI values is suggesting an inherited condition. Factors outside the ABO locus might be responsible for the HE phenotype. Whether the real mechanism of inheritance is either of a polygenic or of a discrete Mendelian nature remains to be elucidated.

As pessoas, durante uma tarefa de caminhar sem visão para alvos previamente visualizados, usualmente realizam-na acuradamente, mesmo sem feedback visual. Quando falham, acidentes, como quedas, podem ocorrer. Estas falhas são geralmente associadas com erros humanos durante os processos de tomada de decisão, de ação ou de percepção. O presente trabalho foi desenvolvido para verificar se tais falhas, numa tarefa de evitar colisão, são associadas à orientação espacial e a tendências do observador. Planejamento: 4 grupos experimentais (Cena Completa, obstáculo e pontos de desvio; Imaginar, somente obstáculo; Sem Obstáculo; somente pontos de desvio; 10s de Atraso, obstáculo e pontos de desvio) x 3 distâncias do obstáculo (três, sete e 12 metros) x 2 distâncias de desvio (0,5 e 1,0 metro). Os observadores observaram a cena e, então, caminharam sem visão para os pontos de evitação. Os resultados mostraram uma acurácia no grupo Cena Completa, o que sugere uma pronunciada ação da informação visual na coordenação de comportamentos motores. A subestimativa encontrada nos outros indica que processos cognitivos, como a tendência do observador, podem conduzir a erros na ação. A acurácia na distância caminhada entre os pontos de desvio a 1,0m pode ser devida ao conforto da situação ou à forte ação da dimensão frontoparalela.