We analyzed 16 Italian breast and breast/ovarian cancer families for BRCA1 germline mutations using a combination of the protein truncation test (PTT) and the single-strand conformation polymorphism ...techniques. Genomic DNA from the affected proband of each family was analyzed by applying the PTT to exon 11 of the BRCA1 gene. This initial screening led to the identification of truncated protein products in three families that were shown to carry three different frameshift mutations. In the families that scored negative in the PTT, single-strand conformation polymorphism analysis of the entire coding sequence of the gene revealed four additional mutations consisting of one nonsense, one in-frame deletion, one frameshift, and one missense mutation (in a family with a case of male breast cancer). The four frameshift mutations resulted in a decreased expression of the mutant allele, whereas no loss of transcript was associated with the other three mutations. All mutant alleles were shown to cosegregate with the cancer phenotype within the families, and none have previously been reported.
Ao propor o título para esta comunicação, veio-me à mente a discussão histórica sobre a avaliação e os rumos que este processo vem tomando, no espaço ─ Escola ─ onde deveria encontrar ambiente ...favorável para fundar seus alicerces e firmar-se como uma nova ciência. Contudo, e contrariamente ao que se esperava, é justamente na escola que o processo avaliativo encontra seus maiores entraves. Tais percepções vêm promovendo no interior do grupo de pesquisa coordenado por mim, reunindo alunos da graduação, da pós-graduação, meus orientados, ex-orientados (mestres) e professores do ensino fundamental e médio uma discussão profícua sobre os instrumentos utilizados para avaliar os alunos e os usos de seus resultados com vistas a garantir uma aprendizagem significativa e um ensino de qualidade. Discute-se e investiga-se ainda, a prática da avaliação em cursos de formação de professores que visam a preparar profissionais para atuarem junto ao ensino fundamental de 1ª a 4ª séries.
Interactions between HIV-1 and EBV were studied in HIV-1-infected EBV-positive lymphoblastoid B cells. Following in vitro exposure of B cells to HIV-1, the number of infected cells reached a plateau ...(25-35%) in approximately 20 days and remained fairly stable thereafter, despite the presence of infectious virus in culture supernatants. HIV-1-positive (gp120+) were separated from HIV-1-negative (gp120-) cells, and the two fractions were further characterized for EBV antigens, bcl-2 expression, and growth capacity in vitro. Compared to gp120- cells, EBNA 1, EBNA 2, and LMP 1 were down-regulated, and the episomal form of EBV-DNA was dramatically decreased in the gp120+ cells. When plated in culture gp120+, but not gp120-, cells died; BZLF1 antigen was not expressed, thus ruling out a reactivation of the EBV lytic cycle. Cytofluorometric, morphological, and molecular analyses disclosed that gp120+ cell death was due instead to apoptosis; evidence of bcl-2 down-regulation in these cells was consistent with this finding. gp120+ cell apoptosis contributed to keeping the level of HIV-1-infected cells at a steady state in the unfractionated culture, where persistent infection was maintained by HIV-1 transmission to B cells newly arising from the proliferation of HIV-1-uninfected cells.
The 11p15.5 chromosomal region contains one or more loci involved in congenital developmental abnormalities and in the genesis of embryonal tumors, such as Wilms' tumor, embryonal rhabdomyosarcoma, ...and hepatoblastoma. In these tumors, a loss of constitutive heterozygosity, selectively involving a specific parental allele, suggests both the presence of onco-suppressor genes and a phenomenon of genomic imprinting. We present evidence that both genetic events could be occasionally involved in hepatoblastoma. In fact, loss of heterozygosity at 11p15.5 could be documented in 3 of 13 patients with hepatoblastoma, and in 2 cases the paternal origin of the residual allele in the tumor was assessed. Moreover, imprinting of the paternal IGFII allele and the maternal H19 allele was confirmed in normal tissues of 5 informative patients. Finally, imprinting relaxation of IGFII was detected in the tumor tissue of 1 patient.
Intraperitoneal injection of lymphoid cells from EBV+ donors into SCID mice might provide a useful tool for studying the pathways of B-cell lymphomagenesis in man. Since previous studies showed that ...donor T cells greatly favor B-cell proliferation and tumor generation in this model, we addressed the host and donor factors involved in limiting or promoting lymphoma development. The number of EBV-infected B-cell precursors was crucial, since purified B lymphocytes, which alone were unable to generate tumors, underwent expansion and established tumor masses when the animals were inoculated with an EBV-containing supernatant. Host factors were critical in limiting tumor development; in vivo NK-cell removal allowed purified B cells to expand and proceed to tumors in the absence of T lymphocytes, whereas potentiation of mouse NK-cell activity prevented tumor generation in PBMC- and LCL-injected animals. The T-cell-derived factors that favor lymphomagenesis could not be identified; IL-2, IL-4, IL-6, and soluble CD23 were not able to promote B-cell expansion, and treatment of PBMC-injected mice with the relevant anti-cytokine anti-sera did not counteract lymphoma development. These experiments also showed that IL-6 plays a minor role, if any, in B-cell lymphoproliferation in this model. Our data indicate that reconstitution of SCID mice with PBMC from EBV+ donors may constitute a useful model for determining the events involved in lymphomagenesis in humans, provided that strict control of all the experimental variables is guaranteed.
Ten months following the diagnosis of Hodgkin's disease (HD), a 46-year-old woman presented cutaneous and leukemic involvement by CD30+ anaplastic large cells, from which a continuously growing, ...exogenous growth factor-independent T cell line was established. The cultured cells are phenotypically and genotypically T cell in type, negative for EBV, HTLV-I and HTLV-II viral sequences, and release soluble CD30 into the supernatant. Karyotype analysis disclosed several chromosomal abnormalities, but none on chromosome 5q. The involvement of the short arm of chromosome 17 prompted us to investigate the TP53 gene by means of the polymerase chain reaction single-strand conformation polymorphism (PCR-SSCP) analysis, but no alterations were found in exons 5-8.
Severe Combined Immune Deficiency mouse tumors, induced by inoculating peripheral blood mononuclear cells from 11 healthy human donors (hu-PBMC-SCID tumors), were used to analyse Epstein- Barr virus ...(EBV) type and strain variations. PCR analysis of EBNA 2- and EBNA 3C-specific sequences showed that EBV type A was present in SCID-mouse tumors induced by PBMC from all donors but one, while, using amplimers for a highly polymorphic region within the latent membrane protein (LMP) coding sequence, 5 different strains could be detected among the samples examined. The same LMP fragment was present in different tumors arising in the same animal, as well as in different mice injected with PBMC from any donor. Compared to B95.8 and AG876 prototype viruses, sequence analysis of LMP variants disclosed a higher homology to the latter, with 33 bp additional repetitions and a few point mutations in specific sites. This study confirms and extends previous data on the presence of a single EBV type and strain in the peripheral blood of most normal healthy subjects using the SCID-mouse system.
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