Neurofibromin is a cytoplasmic protein that is predominantly expressed in neurons, Schwann cells, oligodendrocytes, astrocytes and leukocytes. It is encoded by the gene NF1, located on chromosome 17, at q11.2, and has different biochemical functions, including association to microtubules and participation in several signaling pathways. Alterations in this protein are responsible for a phacomatosis named neurofibromatosis type 1.

The genetic basis for dementias is complex. A common polymorphism in the apolipoprotein E (APOE) gene is considered to be the major risk factor in families with sporadic and late-onset Alzheimer's disease as well as in the general population. The distribution of alleles and genotypes of the APOE gene in late-onset Alzheimer's disease (N = 68), other late-life dementias (N = 39), and in cognitively normal controls (N = 58) was determined, as also was the risk for Alzheimer's disease associated with the ε4 allele. Peripheral blood samples were obtained from a total of 165 individuals living in Brazil aged 65-82 years. Genomic DNA was amplified by the polymerase chain reaction and the products were digested with HhaI restriction enzyme. APOE ε2 frequency was considerably lower in the Alzheimer's disease group (1%), and the ε3 allele and ε3/ε3 genotype frequencies were higher in the controls (84 and 72%, respectively) as were the ε4 allele and ε3/ε4 genotype frequencies in Alzheimer's disease (25 and 41%, respectively). The higher frequency of the ε4 allele in Alzheimer's disease confirmed its role as a risk factor, while ε2 provided a weak protection against development of the disease. However, in view of the unexpectedly low frequency of the ε4 allele, additional analyses in a more varied Brazilian sample are needed to clarify the real contribution of apolipoprotein E to the development of Alzheimer's disease in this population.

A) and four polymorphisms (c.3315-27G>A, V1146I, V1317A, c.4514+11C>G) were identified. These data were recently published.]]>

These preliminary results suggest that p53 mutations are quite frequent in children with Burkitt's lymphoma and may play a role in lymphoma genesis or disease progression.

RESUMO.-[A expressão do maspin nos tumores mamários caninos: um estudo imuno-histoquímico e molecular.] O serpin maspin, um supressor tumoral no câncer de mama foi descrito como inibidor de migração celular e indutor de adesão celular entre a membrana basal e a matriz extracelular resultando na inibição da metástase tumoral. Por outro lado, a alta expressão do maspin está relacionada com um mau prognóstico em outros tipos de câncer. Pouco se sabe sobre a expressão, regulação e função do maspin nos tumores mamários caninos. Neste estudo, foi demonstrada uma perda da expressão de maspin nas células mamárias malignas de cães quando comparadas com um pool de tecido mamário normal de cães, analisado por PCR quantitativa em tempo real. Houve uma expressão fraca maspin em preparações de tumores mamários malignos observadas por imuno-histoquímica. Também foi verificado que a expressão nuclear do maspin em tumores mamários caninos está relacionada a um bom prognóstico. Assim, o maspin pode ser utilizado como um marcador prognóstico nas neoplasias mamárias em cães. The serpin maspin, a tumor suppressor in breast cancer was described as an inhibitor of cell migration and inducer of cell adhesion between the basement membrane and extracellular matrix resulting in inhibition of tumor metastasis. In contrast, overexpression of maspin is correlated with poor prognosis in other types of cancer. Little is known about expression, regulation and function of maspin in canine mammary tumors. It was demonstrated in this study, a loss of maspin expression in malignant canine mammary cells compared with a pool of normal canine mammary tissue, analyzed by quantitative real-time PCR; weak maspin expression in malignant canine mammary tumors were observed by immunohistochemistry. It was also demonstrated that a correlation with nuclear maspin expression and a good prognosis. It is suggested that maspin could be used as a prognostic marker in canine mammary neoplasia.INDEX TERMS: Maspin, canine mammary tumor, immunohistochemistry, molecular biology, prognosis.1