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- 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.
- Development of a biosensor for detection of Escherichia coli in urinePublication . Marques, Patrícia; Vieira, Mónica; Coelho, PedroUrinary tract infections (UTI) are part of the range of infectious diseases and correspond to the abnormal presence of pathogens in some regions of the urinary tract. Although UTIs also affect men, the incidence rate in women is much higher (80% to 90%).(Haddad & Fernandes, 2019).The main causative agent of UTI (approximately 75% of cases) is Escherichia coli (E.coli).(Flores-Mireles et al., 2015) Patients with symptomatic infections will have >105 bacteria/mL and inflammatory cells in their freshly excreted urine.(Chu & Lowder, 2018) UTIs usually have their treatment summarized by taking antibiotics, therefore, in this project, a characterization of the antibiotic resistance of the different strains used are also made.In the present work, we aimed to develop a biosensor to facilitate the early diagnosis of UTIs. Polyclonal anti-E.Coli antibodies of capture (conjugated with Ulfa-Tag) and detection (conjugated with gold) were used to detect the presence of E.Coli through immunochromatography on a nitrocellulose membrane impregnated with anti-Ulfa-Tag antibodies based on the methodology of lateral flow tests. As a control, the gold-conjugated streptavidin-biotin complex was used. Four distinct strains of E.coli were tested, E.coli S3R9, E.coli S3R22, E.coli ATCC 8739 and E.coli ATCC 25922, at concentrations from 103 to 1010 bacteria/mL.Evaluating the results, it was possible to detect the presence of E.Coli at concentrations higher than 108 in samples with intact cells and in extracts. Although it is only possible to detect the presence of E.Coli at very high concentrations, the biosensor developed may, in the future, undergo protocol optimizations in order to detect lower concentrations. In short, we can conclude that the development of a biosensor for the detection of UTIs caused by E. Coli (without the need for the previous culture), will be a decisive milestone in the early diagnosis of this type of infection with direct implications for treatment and prognosis, idealizing a better quality of life for society
- Dermocosmética: qualidade na produção e análise comparativaPublication . Neves, Joana; Oliveira, Ana Isabel; Nascimento, Ana Paula; Cunha, Sofia; Nogueira, Lúcia; Silva, Manuel; Prudêncio, Cristina; Vieira, MónicaOs cosméticos podem ser utilizados na higiene pessoal ajudando a melhorar a aparência. Para a sua produção, é necessário o cumprimento de normas específicas que garantam a qualidade do produto, pelo que o design da estrutura onde estes são produzidos é um fator determinante.
- Development of a method based on HPLC-DAD for the detection and quantification of glutamate and gamma-aminobutyric acidPublication . Machado, Patrícia; Teixeira, Dulce; Vieira, Mónica; Prudêncio, CristinaWith the increasing incidence of neurodegenerative diseases, the need arose to study several molecules that may be useful to the study of new therapies and to treat the symptoms that come with these diseases, as is the case of depression. GABA and glutamate have a very important role in the homeostasis of the organism and molecules of interest and potential from the point of view of diagnosis are revealed. HPLC is a method that allows the detection and quantification of various analytes in different biological matrices, allowing rapid results with high precision, sensitivity and specificity.
- The neuroprotective role of cyanobacteria with focus on the anti-inflammatory and antioxidant potential: Current status and perspectivesPublication . Rodrigues, Flávia; Reis, Mariana; Ferreira, Leonor; Grosso, Clara; Ferraz, Ricardo; Vieira, Mónica; Vasconcelos, Vítor; Martins, RosárioNeurodegenerative diseases are linked to the process of neurodegeneration. This can be caused by several mechanisms, including inflammation and accumulation of reactive oxygen species. Despite their high incidence, there is still no effective treatment or cure for these diseases. Cyanobacteria have been seen as a possible source for new compounds with anti-inflammatory and antioxidant potential, such as polysaccharides (sacran), phycobiliproteins (phycocyanin) and lipopeptides (honaucins and malyngamides), which can be interesting to combat neurodegeneration. As a promising case of success, Arthrospira (formerly Spirulina) has revealed a high potential for preventing neurodegeneration. Additionally, advantageous culture conditions and sustainable production of cyanobacteria, which are allied to the development of genetic, metabolic, and biochemical engineering, are promising. The aim of this review is to compile and highlight research on the anti-inflammatory and antioxidant potential of cyanobacteria with focus on the application as neuroprotective agents. Also, a major goal is to address essential features that brand cyanobacteria as an ecoefficient and economically viable option, linking health to sustainability.
- Development of a new method for the detection and quantification of octopamine and 3-nitrotyrosinePublication . Teixeira, Dulce; Prudêncio, Cristina; Azenha, Manuel; Vieira, MónicaNeurodegenerative diseases affect around 30 million people worldwide, thus new methods that can facilitate research of such diseases are essential. Neurotransmitters, characterised as critical regulators of several neurological disorders, have been the target for the development of such methods. Besides, oxidative/ nitrosative stress has been associated with several neurodegenerative diseases and is thought to play an important role in their pathogenesis. Therefore, the development of bioanalytical methods for quantification of neurotransmitters and oxidative stress-associated molecules seems to be an interesting approach. The aim of this study was to develop a simple, rapid, low-cost and sensitive octopamine (OCT) and 3-nitrotyrosine (3-NT) quantification method for use in biological models.
- Diabetic neuropathy and oxidative stress: a systematic review focused on oxidative stress biomarkers analysisPublication . Cunha, Sofia; Nascimento, Ana Paula; Vieira, Mónica; Prudêncio, CristinaDiabetic neuropathy is a worldwide disease with great impact in modern society. Diabetes may lead to the overproduction of reactive oxygen species, resulting in an imbalance in body’s redox homeostasis. Oxidative stress is pointed as an important phenomenon associated with several disease states, including diabetic neuropathy.
- Evaluation of the potential of marine cyanobacteria towards Alzheimer’s diseasePublication . Moreira, Ana Rita; Silva, Ana Margarida; Vieira, Mónica; Martins, RosárioAlzheimer’s disease (AD) is one of the most prevalent neurodegenerative diseases (NDs) and the major cause of dementia. Despite the constant efforts to achieve cure, no treatment is currently effective and new approaches are urgently needed. Marine biotechnology has been at the frontline for the bioprospection of natural sources to treat ND. Several marine compounds have already provided evidence for anti-AD drugs by acting in mechanisms such as the inhibition of acetylcholinesterase (AChE). Among marine organisms, cyanobacteria have been recognized as a major source of bioactive compounds and the potential towards AD has been highlighted, namely AChE inhibitors. This project is included in a screening program that aims to evaluate the potential of cyanobacteria from the Culture Collection of CIIMAR -LEGE-CC against AD. In this work, 80 fractions of marine cyanobacteria were screened for the potential to inhibit AChE since this is a proven enzyme target to ameliorate the loss of cholinergic signal and to induce cytotoxicity in the neuroblastoma cell line SHY5Y, in the normal fibroblasts cell line 3T3L1, and in the endothelial cells from central nervous system capillaries hCMEC/D3. Results considering the enzymatic assays and cytotoxic assays revealed that the fractions are not toxic or with low toxicity. The strains Phormidium sp; an unidentified filamentous Synechococcales and Nodosilinea nodulosa revealed moderate toxicity towards AChE.
- New therapeutic approaches based on ionic liquidsPublication . Ferraz, Ricardo; Teixeira, Cátia; Prudêncio, Cristina; Teixeira, Dulce; Vieira, Mónica; Gomes, PaulaIonic liquids (ILs) are currently defined as salts (with at least one organic ion) stable above their melting point. They began to be used mainly as solvents, but quickly drew the attention of the Life Sciences, as some of the characteristics of those compounds may be relevant in therapeutic applications. ILs can show more interesting physicochemical properties at the level of active pharmaceutical ingredients such as water solubility, in addition to the fact that ILs (liquids at room temperature and/or human body temperature) do not present polymorphism, an aspect which often limits the conditions of use and therapeutic efficacy of solid active pharmaceutical ingredients. This line of research seeks, through a careful choice of the ions, to fine-tune some of these properties, and to study the combination of two bioactive molecules that have ionizable groups of opposite charge, forming ionic liquids with a dual therapeutic effect.
- The effect of high concentrations of vitamin C on a H2O2 - oxidative stress induced yeast modelPublication . Costa, Ana Rita; Cunha, Sofia; Nascimento, Ana Paula; Vieira, Mónica; Prudêncio, CristinaNowadays, the ageing of population is conducting to a rise in the number of individuals with age-related illnesses, in which neurodegenerative diseases (ND) are included. Regardless of many variations in etiology and diverse mechanisms of cell injury, most of ND share high levels of oxidative stress, which have been highly referred not only as an underlying factor, but also as a feature. Thus, an actual challenge is to evaluate the role of antioxidants on oxidative stress states and evaluate the magnitude of possible therapeutic effects of these agents. In the present study, the toxic effect of hydrogen peroxide (H2O2) and the antioxidative function of vitamin C were investigated using Saccharomyces cerevisiae as a model. Results were achieved by exposing the yeast model to different concentrations of H2O2 and vitamin C, itself or combined, and colony forming units counting after 48 h incubation at 30ºC in Yeast Extract Peptone Dextrose agar plates. The results demonstrated that H2O2 exposure decreased yeast cells viability in a dose-dependent manner and that, at an optimal concentration, vitamin C was able to revert its effects. These results improved the understanding of the reversal effect of antioxidant treatment and, therefore, may be helpful on providing insights on a natural antioxidant-based therapy for ND.