Apolipoprotein E variation at the sequence haplotype level: implications for the origin and maintenance of a major human polymorphism.

Three common protein isoforms of apolipoprotein E (apoE), encoded by the epsilon2, epsilon3, and epsilon4 alleles of the APOE gene, differ in their association with cardiovascular and Alzheimer's disease risk. To gain a better understanding of the genetic variation underlying this important polymorphism, we identified sequence haplotype variation in 5.5 kb of genomic DNA encompassing the whole of the APOE locus and adjoining flanking regions in 96 individuals from four populations: blacks from Jackson, MS (n=48 chromosomes), Mayans from Campeche, Mexico (n=48), Finns from North Karelia, Finland (n=48), and non-Hispanic whites from Rochester, MN (n=48). In the region sequenced, 23 sites varied (21 single nucleotide polymorphisms, or SNPs, 1 diallelic indel, and 1 multiallelic indel). The 22 diallelic sites defined 31 distinct haplotypes in the sample. The estimate of nucleotide diversity (site-specific heterozygosity) for the locus was 0.0005+/-0.0003. Sequence analysis of the chimpanzee APOE gene showed that it was most closely related to human epsilon4-type haplotypes, differing from the human consensus sequence at 67 synonymous (54 substitutions and 13 indels) and 9 nonsynonymous fixed positions. The evolutionary history of allelic divergence within humans was inferred from the pattern of haplotype relationships. This analysis suggests that haplotypes defining the epsilon3 and epsilon2 alleles are derived from the ancestral epsilon4s and that the epsilon3 group of haplotypes have increased in frequency, relative to epsilon4s, in the past 200,000 years. Substantial heterogeneity exists within all three classes of sequence haplotypes, and there are important interpopulation differences in the sequence variation underlying the protein isoforms that may be relevant to interpreting conflicting reports of phenotypic associations with variation in the common protein isoforms.

Preventing HIV transmission: the perspective of inner-city Puerto Rican adolescents.

PURPOSE: To examine the development of HIV prevention strategies that address the concerns and needs of urban Puerto Rican adolescents. METHODS: The study included 542 Puerto-Rican adolescents, divided into age sets of 12 to 14 years and 15 to 19 years. Participants were recruited from community work programs, recreation centers, schools, drug rehabilitation programs, and directly from neighborhood streets in North Philadelphia. A hierarchical series of peer-facilitated group techniques and interviews allowed adolescents to generate, prioritize and explain strategies. The study question was developed in focus groups. Ideas were generated and prioritized in Nominal Technique Groups. The ideas with the highest priority were used to develop a survey that allowed participants to rank those they believed would be most effective. Participants then clarified the top-ranked ideas in open focus groups. RESULTS: In both age sets, the strategy perceived as the most effective in preventing HIV-risk behaviors was "Have people who are HIV-infected talk to teens." Similar ideas addressing this theme varied in perceived effectiveness. The second and third rated ideas among participants aged 12 to 14 years were "Teach teens how HIV infects them, " and "Show teens how people die from AIDS." The second and third rated ideas among participants aged 15 to 19 years were "Show teens what AIDS does to people " and "Have parents be more supportive of teens, so if they are having sex, they can encourage them to use condoms." Other top-ranked ideas included the development of community programs, increased efficacy and availability of condoms, and assessing partners for the risk of HIV infection. Three items revealed significant gender differences. Males were more likely to rate "Give out more free condoms" and "Educate teens in schools about AIDS." Females aged 15 to 19 years were more likely to rate "Teens should know their partner's background before having sex." CONCLUSIONS: To develop effective prevention strategies for youth, their views of the problems and interpretations of proposed solutions must be understood.

Identification of a Brazil-nut allergen in transgenic soybeans.

BACKGROUND: The nutritional quality of soybeans (Glycine max) is compromised by a relative deficiency of methionine in the protein fraction of the seeds. To improve the nutritional quality, methionine-rich 2S albumin from the Brazil nut (Betholletia excelsa) has been introduced into transgenic soybeans. Since the Brazil nut is a known allergenic food, we assessed the allergenicity of the 2S albumin. METHODS: The ability of proteins in transgenic and non-transgenic soybeans, Brazil nuts, and purified 2S albumin to bind to IgE in serum from subjects allergic to Brazil nuts was determined by radioallergosorbent tests (4 subjects) and sodium dodecyl sulfate-polyacrylamide-gel electrophoresis (9 subjects) with immunoblotting and autoradiography. Three subjects also underwent skin-prick testing with extracts of soybean, transgenic soybean, and Brazil nut. RESULTS: On radioallergosorbent testing of pooled serum from four subjects allergic to Brazil nuts, protein extracts of transgenic soybean inhibited binding of IgE to Brazil-nut proteins. On immunoblotting, serum IgE from eight of nine subjects bound to purified 2S albumin from the Brazil nut and the transgenic soybean. On skin-prick testing, three subjects had positive reactions to extracts of Brazil nut and transgenic soybean and negative reactions to soybean extract. CONCLUSIONS: The 2S albumin is probably a major Brazil-nut allergen, and the transgenic soybeans analyzed in this study contain this protein. Our study show that an allergen from a food known to be allergenic can be transferred into another food by genetic engineering.