Browsing by Author "Bravo, Isabel"
Now showing 1 - 3 of 3
Results Per Page
Sort Options
- 3D vs 2D Cell Cultures in the Evaluation of Radiobiological Effects of Exposition to Low Doses - Medical Imaging Levels - of Ionizing RadiationPublication . Costa, Pedro; Caires, Hugo; Lemos, Joana; Cunha, Lídia; Bravo, Joana; Bravo, Isabel; Silva, Regina; Summavielle, Teresa; Metello, Luís F.Pretending to develop advanced biological models to study biological effects of low doses of ionizing radiation and following the actual policies on Animal Sciences, based on 3 R’s Rule (to Reduce, Refine and Replace) – that limits as much as possible the application of animal models – scientific research using cellular models is constantly increasing. Nevertheless, the intrinsic limitations of actual cellular models quite often had been recognized on a significant number of papers pointing a significant number of non-concordances between results obtained using in vitro and in vivo studies. Actually, an increasing number of authors admit that three-dimensional cell culture (and spheroid cell culture in particular) could represent an interesting solution and a step further on use of cellular models. The work here to be presented reflects the first phase on the use of this methodology on the study, evaluation and quantification of cellular effects of low doses – starting on medical imaging level - of exposition to ionizing radiation.
- Study of Non-Targeted Effects Induced on Cell Lines Using Low Doses of Ionizing RadiationPublication . Caires, Hugo R.; Costa, Pedro; Lemos, Joana; Silva, Regina; Bravo, Isabel; Cunha, Lídia; Metello, Luís F.The LNT - Linear-no-Threshold model, used to analyze dose-effect ratios after biological irradiation exposures, theorizes that effects produced are directly proportional to the irradiating doses, with a linear without threshold pattern. Nevertheless, there is a relevant number of evidence, accumulated essentially over the last decade, suggesting that risks inherent to low doses of irradiation cannot be strictly predicted by the LNT model. Among those, there is a significant number of experimental evidence for a variety of low dose induced biological phenomena, which seems to have an impact on modulating the shape of dose-effect curves, namely for expositions below 0.2 Sv, causing the deviation of LNT model. Accumulated evidence demonstrate that cell irradiation induces biological effects, both to directly irradiated cells as well as to cells not exposed to any kind of ionizing radiation, present in a mixed population. This assumption is breaking the classical idea, based on the belief that damage to cellular DNA is only induced by purely ionizing events in cells directly irradiated. This phenomenon, based on cell communication pathways, is termed “Bystander Effect” - clearly highlighted between the “non-targeted effects” of irradiation not considered by the LNT model - being considered one of the biggest paradigm shifts of modern radiobiology.
- Zebrafish and Nuclear Medicine methods and techniques: an each-day improving partnershipPublication . Lemos, Joana; Metello, Luís F.; Caires, Hugo; Costa, Pedro; Martins, Rosario; Bravo, Isabel; Carvalho, António Paulo; Vasconcelos, VítorAims: This work aims the introduction of zebrafish as a very promising and each day more interesting animal model in radiobiology. It will be briefly discussed the most relevant advantages and disadvantages related with the use of zebrafish, mentioning some of the previous studies using this model in Nuclear Medicine and concluding with its potential applications.