In vivo response to the different LET regions of a 55 MeV helium ion beam.

We evaluated the in vivo response to heavy particle irradiation in rat tail epidermis using silver-stained nucleolar organizer regions (AgNOR) as the end-point. The energy degradation of the beam across the circular section of the tail allowed us to study the damage elicited by two different LET regions of a helium beam, i.e. non-Bragg peak (NBP) and Bragg peak (BP), at different sites on the same sample. The tails were locally irradiated with a helium ion beam at different fluences. AgNOR exhibited marked variations between tissue areas only a few micrometers apart within each tail exposed to a given beam fluence. An analysis of the AgNOR variations in NBP and BP areas of tails exposed to different beam fluences revealed a dose-dependent effect. The AgNOR provide quantitative evidence of differential damage in neighboring tissue areas exposed to different LET regions of a helium-ion beam.

AgNOR are sensitive markers of radiation lesions in squamous epithelia.

The possibility of detection of incipient cellular alterations is central to early diagnosis and to clinician's capacity to discriminate between samples that appear similar on routine preparations. We examined the value of silver-stained nucleolar organizer regions (AgNOR) in detecting radio-induced alterations in a model of squamous epithelium biologically similar to oral mucosa. Morphometry of AgNOR has been proven to be of value in the detection of incipient cellular alterations. This method allows for the quantitative evaluation of lesions induced by high doses of radiation long before they become apparent in routine preparations. We herein examine the capacity of AgNOR to reveal the response to low doses of radiation, closer to the therapeutic or accidental dose to which the epithelium of oral mucosa may be exposed.

Avaliação dos marcadores de proliferação celular em tiróides após irradiação externa: estudo experimental em ratos recém desmamados da raça Wistar

Apesar da radioterapia ser reconhecida como arma terapêutca para tratamento de neoplasias malignas, também é admitido o seu poder carcinogético. Este fato é extremamente bem documentado principalmente, em relação a glandula tiróide de crianças submetidas a esta modalidade terapêutica. Através da avaliação da expressão da proteina supressora de tumor p 53 e dos marcadores de proliferação celular (PCNA e gNOR), correlacionados com a morfologia, em tiróides de ratos recem desmamados da raça Wistar, pesquisaram-se alterações precoces da referida glândula que pudessem ser interpretadas como alterações carcinogenéticas. As metodologias de avaliação utilizadas foram a imunohistoquimica e a citoquímica, padronizadas pela Divisão de Patologia do Instituto Adolfo Lutz. A amostra...

Nucleolar organizer regions as markers of incipient cellular alterations in squamous epithelium.

Transcriptionally active nucleolar organizer regions identified by silver staining (AgNOR) vary in number with cellular activity and/or malignant transformation and have been used as a diagnostic tool. A morphometric study of AgNORs was performed in an experimental model of irradiated squamous epithelium (Wistar rat sole skin) 4, 8, and 14 hours and 1, 2, 5, and 7 days post-irradiation with 50 Gy of x-rays. A statistically significant and progressive rise in AgNOR average volume of up to 238% and reduction in AgNOR number/nucleus of up to 40% were detected as a function of post-irradiation time. A statistically significant 46% increase in AgNOR volume was detected as early as 8 h post-irradiation, when no histological changes were observable in routine preparations. These results suggest that AgNORs may be useful as a quantitative marker of incipient changes in cellular activity and caution against the indiscriminate use of AgNORs in the follow-up of lesions which may have been exposed to radiotherapy. Furthermore, this study suggests the possibility of using AgNORs as a sensitive biological dosimeter in cases of uncontrolled exposure to radiation.

Avaliação de marcadores fenotípicos associados à patogenicidade e à epidemiologia no gênero Listeria

A biotipificação das espécies de Listeria através meio de uma metodologia simplificada, bem como a pesquisa de marcadores de patogenicidade, são de suma importância para o diagnóstico bacteriologico. Com este propósito analisou-se a validade dos testes de fermentação de carboidratos ramnose, xilose, x-metil-D-manosídeo e manitol, aliados ao teste de CAMP, na caracterização de 130 amostras de Listeria isolados de fontes hunama e animal. Apenas as espécies...