Molecular cytogenetic characterization of two cases with de novo small mosaic supernumerary marker chromosomes derived from chromosome 16: towards a genotype/phenotype correlation.

Small supernumerary marker chromosomes (sSMC) derived from chromosome 16 are rare and, so far, it is not yet clear which regions of chromosome 16 are critical and have clinical consequences. We have characterized two cases with a ring-shaped sSMC derived from chromosome 16. In case A the sSMC was encountered prenatally and was characterized using centromeric fluorescence in situ hybridization (FISH) probes, subcentromere-specific multicolor FISH (subcenM-FISH), reverse FISH and array-CGH, using a full-tiling BAC array specific for chromosome 16. Case B is a postnatal case and the sSMC was characterized by centromeric FISH probes and subcenM-FISH. Our results, using molecular cytogenetics, showed that both sSMC were derived from chromosome 16, resulting in a de novo mosaic partial trisomy of chromosome 16, involving euchromatic material from 16q. Array painting, in case A, allowed the localization of the sSMC breakpoints, revealing that the sSMC comprised the 33.43-47.02 Mb region of chromosome 16 (16p11.2 to 16q12.1), a region known to harbor some protein-coding genes. In general, the phenotypic consequences of a de novo marker chromosome are difficult to assess. Molecular cytogenetics techniques are a valuable tool for the accurate identification of the origin and content of marker chromosomes, contributing to a more informed prenatal counseling and patient follow-up. Besides multicolor FISH approaches, array painting, combining microdissection and array-CGH, is very useful for mapping size and breakpoints of marker chromosomes, since sSMC are often only present in a small percentage of cells.

Human bronchial epithelial cells malignantly transformed by hexavalent chromium exhibit an aneuploid phenotype but no microsatellite instability.

Hexavalent chromium [Cr(VI)] is a well-recognized human lung carcinogen. In order to gain further insight into Cr(VI)-induced carcinogenesis, we have established an adequate in vitro cellular model for the study of this process. To this end, BEAS-2B cells were used. Chronic exposure of cells to 1 microM Cr(VI) induced changes in the cells' ploidy and a decrease in cloning efficiency, although cultures continued to progress to confluence. After prolonged exposure (12 passages), the culture became heterogeneous, exhibiting areas where apparently normal epithelial cells and morphologically altered cells coexisted. Subsequent culture at a very low density strongly accentuated the Cr(VI)-induced changes in morphology and pattern of growth. Three individual colonies were then ring-cloned and expanded into three subclonal aneuploid cell lines. These subclonal cell lines showed changes in growth pattern and morphology, as well as a karyotype drift concomitant with the overexpression of genes commonly involved in malignant transformation (c-MYC, EGFR, HIF-1alpha and LDH-A). Moreover, when one of these cell lines (RenG2) was injected into nude mice, it showed the ability to induce tumors. This cell line revealed no microsatellite instability (MSI), which points to the expression of a functional MLH1 protein and an active mismatch repair (MMR) system. Therefore, the progression to malignancy of the BEAS-2B cells involved Cr(VI)-induced transformants that retained the ability to repair DNA damage, suggesting that genotoxicity underlies the ongoing carcinogenic process.

First prenatally detected small supernumerary neocentromeric derivative chromosome 13 resulting in a non-mosaic partial tetrasomy 13q.

Neocentromeres are functional centromeres located in non-centromeric euchromatic regions of chromosomes. The formation of neocentromeres results in conferring mitotic stability to chromosome fragments that do not contain centromeric alpha satellite DNA. We present a report of a prenatal diagnosis referred to cytogenetic studies due to ultrasound malformations such as large cisterna magna, no renal differentiation, hypotelorism and ventriculomegaly. Cytogenetic analysis of GTG-banded chromosomes from amniotic fluid cells and fetal blood cells revealed a de novo small supernumerary marker chromosome. Molecular cytogenetic studies using fluorescence in situ hybridization and comparative genomic hybridization showed this marker to be an inverted duplication of the distal portion of chromosome 13q which did not contain detectable alpha satellite DNA. The neocentromeric constriction was located at band 13q31. The presence of a functional neocentromere on this marker chromosome was confirmed by immunofluorescence with antibodies to centromere protein-C. The anatomopathologic study revealed a female fetus with facial dysmorphisms, low set ears and renal dysplasia. Ten small supernumerary neocentromeric chromosomes originating from the distal region of chromosome 13q have been reported to date. There are only three additional cases described with the location of the neocentromere in band 13q31. This is the first reported case detected prenatally.

Use of silica gel chemically modified with zirconium phosphate for preconcentration and determination of lead and copper by flame atomic absorption spectrometry.

An analytical method using silica gel chemically modified with zirconium (IV) phosphate for preconcentration of lead and copper, in a column system, and their sequential determination by flame atomic absorption spectrometry (FAAS), was developed. Sample solutions are passed through a glass column packed with 100 mg of the sorbent material, at pH 4.5, and lead and copper are eluted with 1.0 mol l(-1) HNO(3) at a flow rate of 2.0 ml min(-1). The extraction of copper is affected by Fe(II), Mn(II), Zn(II), Ni(II) and Co(II) while only Fe(II) interferes in the lead determination. These interferences may be overcome with an appropriate addition of a KI or NaF solution. An enrichment factor of 30 was obtained for both metals. While the limits of detection (3sigma) were 6.1 and 1.1 microg l(-1), for Pb and Cu, respectively, the limits of determination were 16.7 and 3.3 microg l(-1). The precision expressed as relative standard deviation (R.S.D.) obtained for 3.3 microg l(-1) of Cu and 16.7 microg l(-1) of Pb were 4.3 and 4.7%, respectively, calculated from ten measurements. The proposed method was evaluated with reference material and was applied for the determination of lead and copper in industrial and river waters.

Necessidades odontológicas dos idosos e seu impacto na saúde geral

Com o objetivo de conhecer a saúde bucal da população idosa brasileira e verificar a mesma, na área de abrangência do ESF- Mato do Engenho, município de Curvelo, M. G., foi realizada uma revisão bibliográfica de artigos científicos na base de dados da biblioteca virtual em saúde - BVS (Lilacs e Scielo). Utilizou-se os seguintes descritores de busca: idoso, saúde bucal, edentulismo, necessidade de prótese dentária e impacto na saúde. Os estudos mostram que a saúde bucal dos idosos brasileiros e dos cidadãos do município é muito precária. Desse modo se conclui que há necessidade de mudanças nas políticas públicas e ao mesmo tempo da construção de um modelo que garanta os princípios constitucionais do SUS, visando não só a saúde bucal, mas a saúde geral do idoso.