Browsing by Author "Cunha, L."
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- Assessing left ventricular dysfunction by the use of three distinct molecular imaging techniquesPublication . Reis, J.; Cunha, L.; Costa, Pedro; Neves, D.; Oliveira, T.; Ferrer-Antunes, A.; João, M. Faria; Metelo, Luís FranciscoLeft ventricular dysfunction might be assessed using distinct molecular imaging modalities. The most relevant are first pass radionuclide ventriculography (FPRV), multigated radionuclide angiography (MUGA) and gated blood-pool SPECT (GBPS) and are very often used for monitoring chemotherapy-related cardiomyopathy. This work aims to correlate these three molecular imaging techniques.
- Assessing radiobiological effects of low doses of ionizing radiation on zebrafish muscle by two-dimensional gel electrophoresisPublication . Lemos, Joana; Campos, A.; Carneiro, M.; Ribeiro, T.; Ponte, F.; Costa, Pedro; Cunha, L.; Carvalho, A.; Metelo, Luís FranciscoThis work relates with the application of zebrafish - Danio rerio - to the study of radiobiological effects of low doses of ionizing radiation. In recent years, the use of zebrafish has grown considerably, pointing more and more as a very interesting model in biomedical research, essentially because of the level of homology shared with the human genome, complemented by an easy and reasonably affordable practical side.
- Direct production of 99mTc-Technetium using low energy cyclotrons and radionuclidic purity: our results so far using natMo-MolybdenumPublication . Metelo, Luís Francisco; Costa, Pedro; Cunha, L.; Jonhson, R.; Matei, L.; Gelbart, W.; Obermair, J.; Artner, C.; Lass, P.; Currie, G.; Craciun, L.; Niculae, D.; Carmo, S.; Alves, F.; Botello, M.Despite the global crisis concerning 99mTc delivering to Nuclear Medicine Departments there isn’t yet a reliable solution. The cyclotron direct production of 99mTc, using the 100Mo(p,2n)99mTc nuclear reaction is our attempt to approach the problem, aiming to become efficient, reliable and sustainable from points of view as reducing drastically the radioactive waste being produced and becoming beneficial for all the involved parts. Between several critical factors, radionuclidic purity of cyclotron-produced 99mTc is being pointed as an issue of concern.
- Evaluation of 18F-FDG PET/CTand low-dose CT performance in diagnosing lymph node metastases among NSCLC patientsPublication . Teodorczyk, J.; Brockhuis, B.; Romanowicz, G.; Cytawa, W.; Wenzel, I.; Kozłowska, J.; Cunha, L.; Silva, A.; Metelo, Luís; Lass, P.The aim of our study is to assess the efficacy of lymph node staging in NSCLC, with particular emphasis on operability, using 18F-FDG-PET-CT and low-dose CT.
- Internal audits: an ally in the promotion of a radiation protection culturePublication . Cunha, L.; Roda, A. L.; Ratão, P.; Capoulas, M.; Ferreira, F.; Sousa, M.; Vasconcelos, H.; Moreira, A. S.; Metelo, Luís FranciscoInternal audits are between the most important tools supporting the management board of any organization. Regardless if they are conducted by na internal or an external auditor, the goals are to assist the organization in defining areas of improvement, while providing precise information needed to accomplish the established goals. We aim to contribute to improving the community awareness of the value of conducting regular audits and its impact on promoting a culture of radiation protection.
- Motion correction software in Myocardial Perfusion Imaging: is it useful?Publication . Cunha, L.; Lamego, J.; Ferreira, S.; Lemos, Joana; Vieira, Domingos; Fonseca, A.; Pires, L.; Neves, D.; João, M. Faria; Pereira, L.; Moreira, A. S.; Metelo, Luís FranciscoMyocardial Perfusion Imaging (MPI) is a very important tool in the assessment of Coronary Artery Disease (CAD) patients and worldwide data demonstrate an increasingly wider use and clinical acceptance. Nevertheless, it is a complex process and it is quite vulnerable concerning the amount and type of possible artefacts, some of them affecting seriously the overall quality and the clinical utility of the obtained data.
- Parameters optimization of filtered back projection in Myocardial Perfusion Imaging reconstructionPublication . Metelo, Luís Francisco; Cunha, L.; Vieira, Domingos; Fonseca, A.; Tavares, A.; Soares, S.; Amorim, I.; Castro, R.; Abrantes, A. M.; Botelho, M. F.Nowadays, even if it is noticed an increasingly wider use of Iterative Methods (IM), a significant number of NM Departments is still routinely using Filtered Backprojection (FBP) as the method of choice in what concerns image processing in MPI. Several authors recommend the use of same filter parameters, no matter what the patient physical characteristics are.
- Possible modulation of dopaminergic neurotransmission function by acetyl-L-carnitinePublication . Cunha, L.; Szigeti, K.; Mathe, D.; Summavielle, T.; Metello, L.Acetyl‐L‐Carnitine (ALC) has a putative neuroprotective effect being used in a variety of conditions. Nevertheless, the underlying molecular mechanisms, particularly regarding the induction of changes in neurotransmitter systems, are still not fully understood. We aim to contribute for the elucidation of the mechanisms by which ALC alters neurotransmitter release, using a cell line and an animal model of exposure to methamphetamine (METH). PC12 cells were incubated with several doses of ALC (0.01 to 1.0 mM) alone or in combination with METH 1.0 or 100 µM for 24h or 72h. When combined, ALC preceded METH administration in 30 minutes. Dopamine (DA) content was determined by high performance liquid chromatography. C57BL/6J mice were used for in vivo assays to assess DA striatal binding. Mice were divided into 4 groups, according to different treatments: group 1 (control), group 2 (ALC, 100 mg/kg), group 3 (METH, 10 mg/kg) and group 4 (ALC+METH). Images were acquired in a SPECT/CT scanner (NanoSPECT/CT, Mediso, Hungary) 70 minutes after 123I‐IBZM injection. Regions of interest were drawn in the striata and in the cerebellum to determine the striatal binding ratio. Increased intracellular levels of DA were observed in PC12 cells at 24h and 72h after the administration of ALC. Cells treated with METH 100 µM displayed decreased intracellular levels of DA. ALC prevented the METH‐induced decrease in DA concentration (p<0.0001). On the other hand, a single dose of 10 mg/kg of METH induced a decrease in striatal D2R binding ratios comparing to control group (between 20% and 30%). Interestingly, over time, ALC was able to reverse the decrease on the radiotracer binding induced by METH. The present study indicates a possible effect of ALC over METH‐induced DA release.
- Properties of tantalum oxynitride thin films produced by magnetron sputtering: the influence of processing parametersPublication . Cristea, D.; Constantin, D.; Crisan, A.; Abreu, Cristiano; Gomes, J. R.; Barradas, N. P.; Alves, E.; Moura, C.; Vaz, F.; Cunha, L.The main purpose of this work is to present and to interpret the change of structure and physical properties of tantalum oxynitride (TaNxOy) thin films, produced by dc reactive magnetron sputtering, by varying the processing parameters. A set of TaNxOy films was prepared by varying the reactive gases flow rate, using a N2/O2 gas mixture with a concentration ratio of 17:3. The different films, obtained by this process, exhibited significant differences. The obtained composition and the interpretation of X-ray diffraction results, shows that, depending on the partial pressure of the reactive gases, the films are: essentially dark grey metallic, when the atomic ratio (N + O)/Ta < 0.1, evidencing a tetragonal β-Ta structure; grey-brownish, when 0.1 < (N + O)/Ta < 1, exhibiting a face-centred cubic (fcc) TaN-like structure; and transparent oxide-type, when (N + O)/Ta > 1, evidencing the existence of Ta2O5, but with an amorphous structure. These transparent films exhibit refractive indexes, in the visible region, always higher than 2.0. The wear resistance of the films is relatively good. The best behaviour was obtained for the films with (N + O)/Ta ≈ 0.5 and (N + O)/Ta ≈ 1.3.
- Single Low-Dose Ionizing Radiation Induces Genotoxicity in Adult Zebrafish and its Non-Irradiated ProgenyPublication . Lemos, Joana; Neuparth, T.; Trigo, M.; Costa, Pedro; Vieira, Domingos; Cunha, L.; Ponte, F.; Costa, P. S.; Metello, Luís; Carvalho, A. P.This study investigated to what extent a single exposure to low doses of ionizing radiation can induce genotoxic damage in irradiated adult zebrafish (Danio rerio) and its non-irradiated F1 progeny. Four groups of adult zebrafish were irradiated with a single dose of X-rays at 0 (control), 100, 500 and 1000 mGy, respectively, and couples of each group were allowed to reproduce following irradiation. Blood of parental fish and whole-body offspring were analysed by the comet assay for detection of DNA damage. The level of DNA damage in irradiated parental fish increased in a radiation dose-dependent manner at day 1 post-irradiation, but returned to the control level thereafter. The level of DNA damage in the progeny was directly correlated with the parental irradiation dose. Results highlight the genotoxic risk of a single exposure to low-dose ionizing radiation in irradiated individuals and also in its non-irradiated progeny.