Browsing by Author "Oliveira, Marco"
Now showing 1 - 7 of 7
Results Per Page
Sort Options
- Harvesting the power of green synthesis: gold nanoparticles tailored for prostate cancer therapyPublication . Oliveira, Marco; Sousa, André; Sá, Sara; Soares, Sílvia; Pereira, Ana Cláudia; Rocha, Ana Catarina; Pais, Patrick; Ferreira, Diogo; Almeida, Cátia; Luís, Carla; Lima, Cláudio; Almeida, Fábio; Gestoso, Álvaro; Duarte, Miguel-Correa; Barata, Pedro; Martins-Mendes, Daniela; Baylina, Pilar; Pereira, Carla F.; Fernandes, RúbenBiosynthetic gold nanoparticles (bAuNPs) present a promising avenue for enhancing biocompatibility and offering an economically and environmentally responsible alternative to traditional production methods, achieved through a reduction in the use of hazardous chemicals. While the potential of bAuNPs as anticancer agents has been explored, there is a limited body of research focusing on the crucial physicochemical conditions influencing bAuNP production. In this study, we aim to identify the optimal growth phase of Pseudomonas aeruginosa cultures that maximizes the redox potential and coordinates the formation of bAuNPs with increased efficiency. The investigation employs 2,6-dichlorophenolindophenol (DCIP) as a redox indicator. Simultaneously, we explore the impact of temperature, pH, and incubation duration on the biosynthesis of bAuNPs, with a specific emphasis on their potential application as antitumor agents. Characterization of the resulting bAuNPs is conducted using ATR-FT-IR, TEM, and UV-Vis spectroscopy. To gain insights into the anticancer potential of bAuNPs, an experimental model is employed, utilizing both non-neoplastic (HPEpiC) and neoplastic (PC3) epithelial cell lines. Notably, P. aeruginosa cultures at 9 h/OD600 = 1, combined with biosynthesis at pH 9.0 for 24 h at 58 ◦C, produce bAuNPs that exhibit smaller, more spherical, and less aggregated characteristics. Crucially, these nanoparticles demonstrate negligible effects on HPEpiC cells while significantly impacting PC3 cells, resulting in reduced viability, migration, and lower IL-6 levels. This research lays the groundwork for the development of more specialized, economical, and ecologically friendly treatment modalities.
- New CTX-M group conferring β-Lactam resistance: A compendium of phylogenetic insights from biochemical, molecular, and structural biologyPublication . Mendonça, Jacinta; Guedes, Carla; Silva, Carina; Sá, Sara; Oliveira, Marco; Accioly, Gustavo; Baylina, Pilar; Barata, Pedro; Pereira, Cláudia; Fernandes, RubenThe production of extended-spectrum β-lactamases (ESBLs) is the main defense mechanism found in Gram negative bacteria. Among all the ESBLs, the CTX-M enzymes appear as the most efficient in terms of dissemination in different epidemiological contexts. CTX-M enzymes exhibit a striking plasticity, with a large number of allelic variants distributed in several sublineages, which can be associated with functional heterogeneity of clinical relevance. This observational analytical study provides an update of this family, currently with more than 200 variants described, from a phylogenetic, molecular, and structural point of view through homology in amino acid sequences. Our data, combined with described literature, provide phylogenetic and structural evidence of a new group. Thus, herein, we propose six groups among CTX-M enzymes: the already stablished CTX-M-1, CTX-M-2, CTX-M-8, CTX-M-9, and CTX-M-25 clusters, as well as CTX-M-151 as the new cluster.
- Oxidative stress genes involved in the virulence-dependent susceptibility to antibiotics in Pseudomonas aeruginosaPublication . Coelho, Pedro Barata; Fernandes, Ruben; Silva, Carina; Oliveira, Marco; Veiga, Marlene; Sá, Sara; Vieira, André; Guedes, Carla; Baylina, PilarPseudomonas aeruginosa is a Gram-negative opportunistic pathogen which rarely causes disease in healthy people. P. aeruginosa, in particular strain PAO1 is also a biological model for studying virulence and bacterial social traits, such as quorum sensing, SOS response among other. Antibiotic response is dependent, among several other factors, to the response to environmental stress conditions. The present study aims to understand the role of 10 PAO1 oxidative gene mutants in the response to antibiotic stress in elastase, protease and pyocyanin-dependent virulence factors. PAO1 was stressed to several antibiotics (penicilins, cephalosporins, macrolides, and quinolones), and the virulence proteins were measured by means of spectroscopic methods. Viability was measured by means of Erythrosin B. PAO1 GGT, GLO1, RubA2, GSH A mutants were the most susceptible to the production of virulence-dependent factors.
- The history and applications of phage therapy in Pseudomonas aeruginosaPublication . Silva, Carina; Sá, Sara; Guedes, Carla; Oliveira, Carla; Lima, Cláudio; Oliveira, Marco; Mendes, João; Novais, Gonçalo; Baylina, Pilar; Fernandes, RúbenThe Pseudomonas aeruginosa is one of the bacteria that cause serious infections due to resistance to many antibiotics can be fatal in severe cases. Antimicrobial resistance is a global public health concern. To solve this problem, interest in phage therapy has revived; some studies are being developed to try to prove the effectiveness of this therapy. Thus, in this opinion article, several historical aspects are addressed as well some applications of phage therapy against P. aeruginosa.
- The magic cocktail: Ampicillin and Biosynthesized gold nanoparticles synergism against Staphylococcus aureusPublication . Oliveira, Marco; Soares, Sílvia; Sá, Sara; Gestoso, Álvaro; Correa-Duarte, Miguel; Baylina, Pilar; Fernandes, Rúben; Pereira, Carla F.Gold nanoparticles (AuNPs) have garnered attention as a potential alternative to conventional antibiotics due to their innovative antibacterial properties. This study demonstrates the successful production of biosynthetic gold nanoparticles (bAuNPs) using Pseudomonas aeruginosa (P. aeruginosa) as spherical nanostructures at 58 ◦C for 24 h, under alkaline pH (9.0). The successful synthesis of bAuNPs was confirmed through UV-Vis spectroscopy, exhibiting a characteristic peak within the 500–600 nm wavelength range, and the evaluation of the main functional groups and morphology were stressed by Fourier Transform Infrared Spectroscopy (FT-IR) and Transmission Electron Microscopy (TEM), respectively. Subsequently, the synthesized bAuNPs were combined with low concentrations of ampicillin and evaluated against Methicillin-Susceptible Staphylococcus aureus (MSSA) and Methicillin-Resistant Staphylococcus aureus (MRSA) through the classical serial dilution method. This innovative approach holds the potential to address the escalating issue of antibiotic resistance, providing a viable and sustainable solution
- The synergic effect of antibiotics is dependent of oxidative stress genes in Pseudomonas aeruginosaPublication . Fernandes, Rúben; Coelho, Pedro Barata; Guedes, Carla; Gojon, Frantz; Oliveira, Marco; Veiga, Marlene; Sá, Sara; Silva, Carina; Baylina, PilarPseudomonas aeruginosa is a Gram-negative opportunistic pathogen commonly found in Cystic fibrosis, infected wound of the diabetic foot among others. Clinical management of such infection depends deeply on the antibiotic therapy. Antibiotic response is dependent, among several other factors, to the response to host stress conditions, such as low-grade inflammation, metabolic conditions and oxidative stress and to social bacteria response such as quorum sensing and biofilm formation. P. aeruginosa, in particular strain PAO1 is also a biological model for studying bacterial biofilm formation. The present study aims to understand the antibiotic synergic response (ampicillin, ceftazidime, ciprofloxacin) in biofilm formation / degradation of 10 PAO1 oxidative gene mutants. Viability was measured by means of Erythrosin B and biofilm formation was measured by Crystal Violet assay. PAO1 GRLX, SEPHS 1, Rub A1, where the strains with a most pronounced biofilm formation and combination of ceftazidme::ciprofloxacin were most efficient in this biological model. The results are interesting, and although they are encouraging, they should be taken with caution.
- Virulence-linked mutations in rubredoxin reductase and glutaredoxin: impact on antibiotic susceptibility and phage therapy in Pseudomonas aeruginosaPublication . Sá, Sara; Silva, Carina; Dias, Maria Clara; Veiga, Marlene; Lopes, Sofia; Fernandes, Ruben; Rocha, Ana Catarina; Pais, Patrick J.; Oliveira, Marco; Mendes, João; Novais, Gonçalo; Luís, Carla; Gestoso, Álvaro; Macedo, José Mário; Martins-Mendes, Daniela; Pereira, Ana Cláudia; Baylina, PilarPseudomonas aeruginosa (PAO1) is an opportunistic pathogen, lethal in immunocompromised individuals. The clinical management of PAO1 infections still depends deeply on antibiotic therapy. However, this therapy has been alarmingly overpowered by growing bacterial resistance mechanisms over the years. One of these bacterial mechanisms is quorum sensing (QS). QS is involved in the production of biofilm, rhamnolipids and pyocyanin, among other factors. The present study aimed to study the effect of the mutations in the genes of rubredoxin (Rub A1 and Rub A2) and glutaredoxin (GLRx) in the production of virulence traits and susceptibility of PAO1 to the antibiotic ciprofloxacin (CIP) and to infection by a phage cocktail. Rub A1, Rub A2, and GLRx showed a decrease in the expression of genes lasI, lasR, mvfR, and rpsL when compared to the wild type, PAO1. Rub A1 and Rub A2 also showed a decrease in the expression of the gene pqsA, while the mutant GLRx showed an increase of over 200% in expression compared to PAO1. The biofilm produced by the mutants Rub A1, Rub A2, and GLRx increased more than 1.5 times in comparison to PAO1, with statistical significance (p < 0.0001). In the viability assay, the mutant strain Rub A2 was the most susceptible to ciprofloxacin in both concentrations tested (p < 0.0001). The production of proteases increased in the mutant strains when compared to PAO1 (p < 0.05). However, there was a decrease in the production of rhamnolipids and pyocyanins in the mutant strains. In the phage assay, we could perceive a reduction in the growth of the mutant strains when compared to PAO1. Additionally, after the addition of the phages, all the strains showed susceptibility to the phage assay (p < 0.0001), observed in the decrease in the absorbance values. These results may highlight the relevance of the genes Rub A1, Rub A2, and GLRX in the proliferation and treatment of infections with PAO1. Overall, this study gives preliminary insights into how gene expression may be helpful in strategies to overcome antibiotic resistance.