RESUMEN
In this study we present for the first time detailed scanning force microscopy (SFM) investigations of carbon ion induced damages in plasmid DNA in order to obtain information about the biological effectiveness of particle radiation. For this purpose, we have combined SFM and gel electrophoresis measurements in a dose range between D = 0 Gy and 5000 Gy. After irradiation with C ions, the percentage of double-strand breaks (DSBs) increases drastically, i.e. from initially 0% for D = 0 Gy to 38% for D = 5000 Gy. Increasing the dose over the total range is accompanied by a shortening of the average fragment length from L = 1100 nm to L = 575 nm. In addition to our experiments, the average numbers of induced DSBs per irradiated plasmid and per broken plasmid have been calculated from the SFM measurements. The most important among the numerous results is that a significant amount of plasmids has suffered more than two DSBs for all applied doses, indicating multiple DSBs. The number of DSBs per broken plasmid increases from approximately 1.7 after irradiation with a dose of D = 250 Gy to 3.2 after exposure to the highest dose of D = 5000 Gy. The results provide experimental data for the spatially correlated production of DSBs after carbon irradiation, that are relevant to the understanding of its biological effectiveness.
Asunto(s)
Radioisótopos de Carbono/farmacología , Daño del ADN , Microscopía de Fuerza Atómica , Plásmidos/efectos de la radiación , Bacteriófago phi X 174/genética , Carbono/química , Roturas del ADN de Doble Cadena/efectos de la radiación , Electroforesis en Gel de Agar , Iones/química , Modelos Teóricos , Plásmidos/químicaRESUMEN
5-FU exhibits a high fluorescence after irradiation with UV-vis light. An enhancement of the cytostatic activity of 5-FU under UV-vis irradiation was observed on an in vivo experimental model.
Asunto(s)
Antimetabolitos Antineoplásicos/efectos de la radiación , Antimetabolitos Antineoplásicos/toxicidad , Fluorouracilo/efectos de la radiación , Fluorouracilo/toxicidad , Fármacos Fotosensibilizantes/uso terapéutico , Animales , Relación Dosis-Respuesta a Droga , Fluorescencia , Terapia por Láser , Seudotumor Orbitario/tratamiento farmacológico , Seudotumor Orbitario/etiología , Conejos , Espectroscopía Infrarroja por Transformada de Fourier , Factores de Tiempo , Rayos UltravioletaRESUMEN
The absorption, excitation and emission spectra of methotrexate (MTX) solutions in natural saline water and sodium hydroxide at 10(-4)-10(-5) MpH=8.4 were measured, while they were exposed to coherent and uncoherent visible and near ultraviolet (UV) light. Xe and Hg lamp and also a nitrogen pulsed laser radiation were used. The absorption spectra exhibited spectral bands between 225 nm and 450 nm. The 200 nm - 500 nm excitation spectra were measured with emission centred on 470 nm; fluorescence excitation was observed at 340 nm and 370 nm; emission fluorescence was detected between 400 nm and 600 nm, showing a maximum at 470 nm. Spectra modifications, non-linearly depending on exposure time (varying from 3 min to 180 min), indicated the photodissociation of MTX to the fluorescent compound 2,4 diamino-formylpteridine. In a preliminary in vivo experiment, rapid destruction of neovascularisation was observed in the MTX-impregnated conjunctive of the rabbit eye exposed to uncoherent UV and visible light.