Solar Radiation Damage to Human Skin Mitochondria

The central objective of this study was to assess solar radiation-induced changes in cellular function, mitochondrial function and mitochondrial DNA to further investigate the role of these energy-dedicated and metabolically essential organelles in the response to the main environmental stressor associated with skin cancer initiation. An in vitro approach was chosen employing the human malignant melanoma (A375) and human amelanotic melanoma (C32) cells and the human spontaneously immortalized keratinocytes (HaCaT). A Q-Sun Solar Simulator was used to expose cells to low-level simulated solar radiation (SSR) as it provides a mimic of solar radiation that is environmentally relevant in the UV spectrum. Cell viability, apoptosis, DNA and protein content were analysed as cellular response end-points and they have been observed to change in a cell type-specific and time- dependent manner post SSR. Increases in mitochondrial genome number and mtDNA3895 were observed as an early response to low-dose SSR in human skin cells. The common deletion mtDNA4977t,h ough detected, did not directly increase in frequency with solar radiation exposure though the mtDNA3895 deletion, previously found to be associated with solar radiation exposure, was observed to be substantially increased in a cell-type and dose-dependent manner in skin cells post SSR. Impaired mitochondrial bioenergetics, dynamics and recycling may play a significant role in the melanoma tumour initiation and progression in humans post systematic solar radiation over-exposure. Furthermore the sensitive nature of the mitochondrial population of skin cells should not be underestimated as dynamic changes in their biology are evident even in cell populations that received low level irradiation of simulated solar radiation

Chimerism 47,XY,+21/46,XX in a female infant with anencephaly and other congenital defects

Chimerism is rare in humans and is usually discovered accidentally when a 46,XX and 46,XY karyotype is found in a same individual. We describe a malformed female infant with neural tube defect (NTD) and a 47,XY,+21[5]/46,XX[30] karyotype.3637Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

Estudo de mosaicismos cromossomicos pela tecnica do FISH em nucleo interfasico

Orientador: Denise Pontes CavalcantiDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciências MédicasResumo: As aneuploidias constituem a principal alteração genética encontrada na espécie humana e podem envolver tanto cromossomos autossômicos quanto sexuais. As neuploidias em mosaicos são menos freqüentes do que as trissomias livres, podendo apresentar-se, do ponto de vista clínico, de forma bastante heterogênea. O mosaicismo acontece devido ao surgimento de uma segunda linhagem celular (trissômica ou dissômica) durante o período pós-zigótico. A técnica de FISH em núcleo interfásico tem sido descrita como mais sensível na detecção de mosaicismos, por prescindir do cultivo celular e por possibilitar a análise de um grande número de células de cada vez. Neste trabalho utilizou-se a citogenética convencional e a do FISH interfásico, em 3 grupos de indivíduos: 1) 10 pacientes com mosaicismo cromossômico conhecido (3 mosaicos tetraplóides-diplóides, 1 mosaico do cromossomo 15, 1 mosaico do cromossomo 14, 1 mosaico de cromossomo marcador e 4 casos de mosaicos do cromossomo 21); 2) 9 pacientes polimalformados com cariótipo normal e 3) 10 controles compostos por recémnascidos clinicamente normais. Foram utilizadas sondas centroméricas dos respectivos cromossomos envolvidos em cada mosaico específico, nos pacientes do grupo 1 e sondas centroméricas do cromossomo 16, para a pesquisa de criptomosaicismo nos pacientes do segundo grupo, bem como, para estabelecer a sensibilidadedas sondas no grupo controle. O diagnóstico de mosaicismo cromossômico foi confirmado pelo FISH interfásico, em todos os pacientes do grupo 1. As proporções de células aneuplóides apresentaram-se ora coincidentes, ora diferentes, inclusive com detecção de criptomosaicismo em fibroblastos do paciente portador de mosaicismo do cromossomo 15. Criptomosaicismodo cromossomo 16 não foi detectado em nenhum dos 10 pacientes do grupo 2. O presente estudo reforça a necessidade de estudo em mais de um tecido em casos de mosaicismo. Sugere-se também que, sempre que possível, os mosaicismos cromossômicos sejam investigados por FISH interfásicoAbstract: Chromosome aneuploidy is the most common human genetic change. Aneuploidy may involve both autosomic and sexual chromosomes. The mosaic aneuploidies occur less frequently than free trissomies. Moreover, mosaic patients may show a wide diversity of phenotipical effects of trissomy. Phenotipical changes may involve since just a few sintoms to similar clinical change observed on &ee trissomy carriers. Mosaicism arrises from the development of a viable second cellular lineage on the post-zigotic stage. The usual mosaicism classification is based on the amount of DNA that has changed which may range from a base pair to a loss of a whole chromosome. On this study we have focused on 3 working groups: 1) 10 patients with known mosaicism (3 mosaics tetraploid-diploid, 1 mosaic of the chromosome 15, 1 mosaic of chromosome 14, 1 mosaic of marker chromosome and 4 cases of mosaicim of chromosome 21); 2) 9 malformed patients with normal karyotype and 3) 10 controls composed by normal newborns. We have utilized centromeric probes of each chromosome involved in specific mosaicism of the patients from group 1 and chromosome 16 centromeric probes for the research of hidden mosaicism in the patients of the second group, as well as, to establish the probes sensibility in the control group. Mosaicism was confirmed by FISH in all patients from group 1. The proportions of aneuploid cells were similar in some cases and different in others. Chromosome 16 hidden mosaicism was not detected in group 2. The present study reinforce the need of studing different tissues in cases of mosaicism. It also suggests, whenever possible, the interfasic FISH investigation of mosaic patientsMestradoCiencias BiomedicasMestre em Ciências Médica

Leber's Hereditary Optic Neuropathy: Clinical And Molecular Profile Of A Brazilian Sample.

The aim of this study was to describe clinical features and search for primary mitochondrial DNA (mtDNA) mutations in 13 unrelated Brazilian patients with Leber's hereditary optic neuropathy (LHON). Analysis of the G11778A, G3460A, and T14484C mutations was done by polymerase chain reaction and restriction fragment length polymorphism, and mutations were confirmed by direct sequencing. Mean age of onset was 24.5 years and all cases were bilateral. Sex ratio (12M:1F) and frequency of simultaneous involvement (9/13) were higher than in other studies. In nine cases there was familial recurrence: 24 male and two female relatives. Ten patients had a mutation: G11778A in six, T14484C in three and one G3460A. The frequency of patients bearing a primary mutation was lower than that described in multicentric studies but similar to that observed among Asians. A higher frequency of the T14484C mutation was detected. The contribution of Amerindians and Africans to the Brazilian mtDNA pool may account for differences in the type and frequency of primary LHON mutations.31126-