Browsing by Author "Prudêncio, Cristina"
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- 11 - Collagen-like materials for tissue regeneration and repairPublication . Teixeira, Cátia; Ferraz, Ricardo; Prudêncio, Cristina; Gomes, PaulaPeptides can be designed to recreate the higher-order assembly (triple helix) and biological function of natural collagens. Collagen triple-helical domain contains Gly-Xaa-Yaa triplets where Xaa and Yaa are frequently proline and hydroxyproline, respectively. Glycine must be in every third position forming a hydrogen bond to an adjacent proline to stabilize collagen structure. Hydroxyproline residues are important in the thermal stability of the collagen triple-helix conformation. Although it is difficult to produce a stable triple helix, collagen-like peptides can be used to produce scaffolds that mimic natural tissue networks for biomedical engineering, without the liabilities of nonhuman natural collagens such us immunogenicity and pathogen transmission. This chapter describes the major approaches towards synthesis of collagen-like peptides, essentially aimed at production of artificial biocompatible and biofunctional frameworks for regenerative medicine.
- 3-Nitrotyrosine quantification methods: Current concepts and future challengesPublication . Teixeira, Dulce; Fernandes, Rúben; Prudêncio, Cristina; Vieira, MónicaMeasurement of 3-nitrotyrosine (3-NT) in biological samples can be used as a biomarker of nitrosative stress, since it is very stable and suitable for analysis. Increased 3-NT levels in biological samples have been associated with several physiological and pathological conditions. Different methods have been described for the detection and quantification of this molecule, such as (i) immunological methods; (ii) liquid chromatography, namely high-pressure liquid chromatography (HPLC)-based methods that use ultraviolet-visible (UV/VIS) absorption, electrochemical (ECD) and diode array (DAD) detection, liquid chromatography-mass spectrometry (LC-MS) and liquid chromatography-tandem mass spectrometry (LC-MS/MS); (iii) gas chromatography, such as gas chromatography-mass spectrometry (GC-MS) and gas chromatography-tandem mass spectrometry (GC-MS/MS). Methods A literature review on nitrosative stress, protein nitration, as well as 3-NT quantification methods was carried out. Results This review covers the different methods for analysis of 3-NT that have been developed during the last years as well as the latest advances in this field. Overall, all methods present positive and negative aspects, although it is clear that chromatography-based methods present good sensitivity and specificity. Regarding this, GC-based methods exhibit the highest sensibility in the quantification of 3-NT, although it requires a prior time consuming derivatization step. Conversely, HPLC does not require such derivatization step, despite being not as accurate as GC. Conclusion It becomes clear that all the methods described during this literature review, although accurate for 3-NT quantification, need to be improved regarding both sensitivity and specificity. Moreover, optimization of the protocols that have been described is clearly needed.
- Adipocyte proteome and secretome influence inflammatory and hormone pathways in gliomaPublication . Almeida, Joana; Costa, J.; Coelho, Pedro; Cea, V.; Galesio, M.; Noronha, J. P.; Diniz, M. S.; Prudêncio, Cristina; Soares, R.; Sala, C.; Fernandes, RúbenGliomas represent the most common primary malignant brain tumors in adults, with an extremely poor prognosis. Among several risk factors, lifestyle was also recently identified as a major risk factor for the development of primary glioma. In the present study, we explore the relationship between obesity and glioma in a cellular model. Thus, we have study the influence of adipocytes secretome on glioma cell line GL261. Using the 3T3-L1 adipocyte cell line, and its conditioned medium (adipokines-enriched medium), we showed that adipocyte-released factors relate with glioma angiogenic, growth, hormones and metabolic behavior by MALDI-TOF-MS and proteomic array analysis. In a first view, STI1, hnRNPs and PGK1 are under expressed on CGl. Similarly, both carbonic anhydrase and aldose reductase are even suppressed in glioma cells that grown under adipokines-enriched environment. Contrariwise, RFC1, KIF5C, ANXA2, N-RAP and RACK1 are overexpressed in GL261 cell the in the presence of the adipokines-enriched medium. We further identified the factors that are released by adipocyte cells, and revealed that several pro-inflammatory and angiogenic factors, such as IL-6, IL-11, LIF, PAI-1, TNF-α, endocan, HGF, VEGF IGF-I, were secreted to the medium into a high extent, whereas TIMP-1 and SerpinE1 were under expressed on CGl. This study discloses an interesting in vitro model for the study of glioma biology under a "obesity" environment, that can be explored for the understanding of cancer cells biology, for the search of biomarkers, prognostic markers and therapeutic approaches.
- Adipocyte secretome increases radioresistance of malignant melanocytes by improving cell survival and decreasing oxidative statusPublication . Coelho, Pedro; Silva, Liliana; Faria, Isabel; Vieira, Mónica; Monteiro, Armanda; Pinto, Gabriela; Prudêncio, Cristina; Fernandes, Rúben; Soares, RaquelRadiotherapy is a treatment option for the majority of malignancies. However, because melanoma is known to be radioresistant, the use of ionizing radiation as an adjuvant therapy in cutaneous melanoma patients is ineffective. Obesity has now been recognized as a risk factor for melanoma. High adiposity is generally associated with a more pro-oxidative status. Oxidative stress is a major player in radiation therapy and also a common link between obesity and cancer. Several adipocyte-released proteins are known to have a role in controlling cellular growth and pro-survival signaling. For that reason, we investigated the influence of 3T3-L1 mature adipocyte secretome in B16-F10 malignant melanocyte radiosensitivity. We evaluated B16-F10 cell survival and redox homeostasis when exposed to four daily doses of ionizing radiation (2 Gy per day) up to a total of 8 Gy in a medical linear accelerator. B16-F10 melanocytes exhibited slight alterations in survival, catalase activity, nitrative stress and total oxidant concentration after the first 2 Gy irradiation. The motility of the melanocytes was also delayed by ionizing radiation. Subsequent irradiations of the malignant melanocytes led to more prominent reductions in overall survival. Remarkably, 3T3-L1 adipocyte-secreted molecules were able to increase the viability and migration of melanocytes, as well as lessen the pro-oxidant burden induced by both the single and cumulative X-ray doses. In vitro adipocyte-released factors protected B16-F10 malignant melanocytes from both oxidative stress and loss of viability triggered by radiation, enhancing the radioresistant phenoyype of these cells with a concomitant activation of the AKT signaling pathway These results both help to elucidate how obesity influences melanoma radioresistance and support the usage of conventional medical linear accelerators as a valid model for the in vitro radiobiological study of tumor cell lines.
- Adipocyte-released factors enhance melanocyte’s proliferation and motilityPublication . Fernandes, Rúben; Coelho, Pedro; Almeida, Joana; Prudêncio, Cristina; Soares, RaquelObesity, favored by the modern lifestyle, acquired epidemic proportions nowadays. Obesity has been associated with various major causes of death and morbidity including malignant neoplasms. Cutaneous melanoma incidence rates have also been increasing uring the last four decades in several countries. Obesity involvement in melanoma etiology has been recognized, but the implicated mechanisms remain unclear. We propose to address the above relationship and investigate the mechanism interplaying between obesity and an increased risk of melanoma onset.
- Affinity coefficient for clustering autoregressive moving average modelsPublication . Nascimento, Ana Paula; Oliveira, Alexandra; Faria, Brígida Mónica; Pimenta, Rui; Vieira, Mónica; Prudêncio, Cristina; Nicolau, Helena BacelarIn various fields, such as economics, finance, bioinformatics, geology, and medicine, namely, in the cases of electroencephalogram, electrocardiogram, and biotechnology, cluster analysis of time series is necessary. The first step in cluster applications is to establish a similarity/dissimilarity coefficient between time series. This article introduces an extension of the affinity coefficient for the autoregressive expansions of the invertible autoregressive moving average models to measure their similarity between them. An application of the affinity coefficient between time series was developed and implemented in R. Cluster analysis is performed with the corresponding distance for the estimated simulated autoregressive moving average of order one. The primary findings indicate that processes with similar forecast functions are grouped (in the same cluster) as expected concerning the affinity coefficient. It was also possible to conclude that this affinity coefficient is very sensitive to the behavior changes of the forecast functions: processes with small different forecast functions appear to be well separated in different clusters. Moreover, if the two processes have at least an infinite number of π- weights with a symmetric signal, the affinity value is also symmetric.
- Alterações anatómicas induzidas pela idade na coluna vertebral: intervenção para melhoria da saúde da comunidadePublication . Ribas, Jorge; Ribas, C.; Prudêncio, CristinaO aumento do envelhecimento da população implica uma crescente importância na implementação da política de cuidados de saúde primários. O envelhecimento leva a profundas alterações na morfologia da coluna vertebral do indivíduo. Estas alterações não estão ainda devidamente caracterizadas pelo que é necessário estudar e tipificar quais as mudanças induzidas pela idade. Desta forma será possível avaliar de que forma o patológico se poderá enquadrar num padrão normal de envelhecimento.
- Análise fatorial de doenças não transmissíveis em função das taxas de mortalidade ao longo do tempoPublication . Nascimento, Ana Paula; Prudêncio, Cristina; Vieira, Mónica; Faria, Brígida Mónica; Pimenta, Rui; Bacelar-Nicolau, HelenaA Saúde Pública visaestudar, prevenir doenças, prolongar a vida e melhorar a qualidade de vida por meio de esforços organizados e escolhas informadas. Assim, é necessárioconhecer e analisar os fatores de saúde de uma população. A Análise de Dados Multivariada difere da Análise Estatística Multivariada clássica (confirmatória), pois nesta última o papel central está no modelo e nas inferências estatísticas, enquanto que na análise de dados multivariada são os dados que assumem o papel primordial. Atécnica de análise fatorial pode ajudar na procura de causas comuns ou fatores de risco para melhorar a medicina preventiva. Pretende-se, com o presente estudo, encontrar fatores de doenças não transmissíveis eventualmente sugestivos de um comportamento comum das mesmas, utilizando análise fatorial. Para encontrar fatores que expliquem as associações entre doenças não transmissíveis, foi aplicada a análise fatorial separadamente para o sexo masculino e feminino, e considerando como variáveis as taxas de mortalidade padronizadas ao longo do tempo de cada uma das doenças. Foram identificados três fatores de doenças não transmissíveis, no sexo feminino, explicando 80,36% da variância e quatro fatores de doenças não transmissíveis,no sexo masculino, explicando 77,22% da variância. Em ambos os sexos as doenças cerebrovasculares e a cardiopatia isquémica contribuem positivamente para o primeiro fator, o que é comum ser encontrado na literatura no caso do sexo masculino, aplicando métodos de cluster analysis. A análise fatorial juntamente com outras metodologias de análise de dados multivariados, pode ajudar na identificação de causas comuns ou fatores de risco para melhorar a medicina preventiva. O estudo dos fatores de risco e/ou mecanismos fisiopatológicos comuns que de uma forma direta ou indireta, possam potenciar o desenvolvimento comum das patologias encontradas nos grupos/fatores é prioritário dada a relevância das doenças não transmissíveis.
- Antibacterial activity of Ionic Liquids based on ampicillin against resistant bacteriaPublication . Ferraz, Ricardo; Teixeira, Vânia; Rodrigues, Débora; Prudêncio, Cristina; Fernandes, Rúben; Noronha, João Paulo; Petrovski, Zeljko; Branco, LuísAntibacterial activity of novel Active Pharmaceutical Ingredient Ionic Liquids (API-ILs) based on ampicillin anion [Amp] have been evaluated. They showed growth inhibition and bactericidal properties on some sensitive bacteria and especially some Gram-negative resistant bacteria when compared to the [Na][Amp] and the initial bromide and chloride salts. For these studies were analysed the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBIC) against sensitive Gram-negative bacteria Escherichia coli ATCC 25922 and Klebsiella pneumonia (clinically isolated), as well as sensitive Gram positive S. Aureus ATCC 25923, Staphylococcus epidermidis and Enterococcus faecalis and completed using clinically isolated resistent strains: E. coli TEM CTX M9, E. coli CTX M2 and E. coli AmpC Mox. From the obtained MIC values of studied APIs-ILs and standard [Na][Amp] were derived RDIC values (relative decrease of inhibitory concentration). High RDIC values of [C16Pyr][Amp] especially against two resistant Gram-negative strains E. coli TEM CTX M9 (RDIC>1000) and E. coli CTX M2 (RDIC>100) point clearly to a potential promising role of APIs-ILs as antimicrobial drugs especially against resistant bacterial strains.
- Antibacterial activity of ionic liquids based on betalactamantibiotics against resistant bacteriaPublication . Dias, Vitorino; Santos, Miguel; Prudêncio, Cristina; Noronha, João P.; Grilo, Inês R.; Sobral, Rita G.; Dias, Ana Rita; Branco, Luís C.; Ferraz, RicardoThe cases of antibiotic resistance are increasing and becoming more and more common, giving rise to a new problem for public health. Therefore, the discovery of new antibiotics is important and necessary.