Browsing by MeSH term "Oxidants"
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Publication Capsule enlargement in Cryptococcus neoformans confers resistance to oxidative stress suggesting a mechanism for intracellular survival(Wiley, 2008-10) Zaragoza, Oscar; Chrisman, Cara J; Castelli, Maria Victoria; Frases, Susana; Cuenca-Estrella, Manuel; Rodriguez-Tudela, Juan Luis; Casadevall, Arturo; Ministerio de Educación y Ciencia (España); Instituto de Salud Carlos IIICryptococcus neoformans is a facultative intracellular pathogen. The most distinctive feature of C. neoformans is a polysaccharide capsule that enlarges depending on environmental stimuli. The mechanism by which C. neoformans avoids killing during phagocytosis is unknown. We hypothesized that capsule growth conferred resistance to microbicidal molecules produced by the host during infection, particularly during phagocytosis. We observed that capsule enlargement conferred resistance to reactive oxygen species produced by H(2)O(2) that was not associated with a higher catalase activity, suggesting a new function for the capsule as a scavenger of reactive oxidative intermediates. Soluble capsular polysaccharide protected C. neoformans and Saccharomyces cerevisiae from killing by H(2)O(2). Acapsular mutants had higher susceptibility to free radicals. Capsular polysaccharide acted as an antioxidant in the nitroblue tetrazolium (NBT) reduction coupled to beta-nicotinamide adenine dinucleotide (NADH)/phenazine methosulfate (PMS) assay. Capsule enlargement conferred resistance to antimicrobial peptides and the antifungal drug Amphotericin B. Interestingly, the capsule had no effect on susceptibility to azoles and increased susceptibility to fluconazole. Capsule enlargement reduced phagocytosis by environmental predators, although we also noticed that in this system, starvation of C. neoformans cells produced resistance to phagocytosis. Our results suggest that capsular enlargement is a mechanism that enhances C. neoformans survival when ingested by phagocytic cells.Publication Evidence of Higher Oxidative Status in Depression and Anxiety(Hindawi, 2014) Grases, G.; Colom, M. A.; Fernández, Rafael Alonso; Costa-Bauza, Antonia; Grases, FWe use a simple method for evaluating antioxidative status, by measuring the redox potential of urine, and correlate the findings with measures of anxiety and depression. We include 63 individuals (28 males and 35 females aged between 20 and 65 years). The validated anxiety State-Trait Anxiety Inventory questionnaire and the validated BDI (Beck Depression Inventory) questionnaire were used to evaluate anxiety and depression. Antioxidative status was determined by measuring the redox potential of urine collected in standard conditions. Correlation of the antioxidant capacity of urines evaluated using the ferric ion/specific dye method or through redox potential using the platinum electrode demonstrated the suitability of this last procedure. We found that normal anxiety state values corresponded to low urine redox potentials, whereas higher anxiety states were associated with high urinary redox potential. We also found that individuals with normal BDI values had significantly lower urine redox potentials than individuals with higher BDI values.Publication Oxidative Stress in Drug-Induced Liver Injury (DILI): From Mechanisms to Biomarkers for Use in Clinical Practice(Multidisciplinary Digital Publishing Institute (MDPI), 2021-03-05) Villanueva-Paz, Marina; Morán, Laura; López-Alcántara, Nuria; Freixo, Cristiana; Andrade, Raúl J.; Lucena, M Isabel; Cubero, Francisco Javier; [Villanueva-Paz,M; Andrade,RJ; Lucena,MI] Unidad de Gestión Clínica de Gastroenterología, Servicio de Farmacología Clínica, Instituto de Investigación Biomédica de Málaga-IBIMA, Hospital Universitario Virgen de la Victoria, Universidad de Málaga, CIBERehd, Málaga, Spain. [Morán,L; López-Alcántara,N; Cubero,FJ] Department of Immunology, Ophthalmology and ENT, Complutense University School of Medicine, Madrid, Spain. [Morán,L] Health Research Institute Gregorio Marañón (IiSGM), Madrid, Spain. [Freixo,C] CINTESIS, Center for Health Technology and Services Research, do Porto University School of Medicine, Porto, Portugal. [Cubero,FJ] 12 de Octubre Health Research Institute (imas12), Madrid, Spain.Idiosyncratic drug-induced liver injury (DILI) is a type of hepatic injury caused by an uncommon drug adverse reaction that can develop to conditions spanning from asymptomatic liver laboratory abnormalities to acute liver failure (ALF) and death. The cellular and molecular mechanisms involved in DILI are poorly understood. Hepatocyte damage can be caused by the metabolic activation of chemically active intermediate metabolites that covalently bind to macromolecules (e.g., proteins, DNA), forming protein adducts-neoantigens-that lead to the generation of oxidative stress, mitochondrial dysfunction, and endoplasmic reticulum (ER) stress, which can eventually lead to cell death. In parallel, damage-associated molecular patterns (DAMPs) stimulate the immune response, whereby inflammasomes play a pivotal role, and neoantigen presentation on specific human leukocyte antigen (HLA) molecules trigger the adaptive immune response. A wide array of antioxidant mechanisms exists to counterbalance the effect of oxidants, including glutathione (GSH), superoxide dismutase (SOD), catalase, and glutathione peroxidase (GPX), which are pivotal in detoxification. These get compromised during DILI, triggering an imbalance between oxidants and antioxidants defense systems, generating oxidative stress. As a result of exacerbated oxidative stress, several danger signals, including mitochondrial damage, cell death, and inflammatory markers, and microRNAs (miRNAs) related to extracellular vesicles (EVs) have already been reported as mechanistic biomarkers. Here, the status quo and the future directions in DILI are thoroughly discussed, with a special focus on the role of oxidative stress and the development of new biomarkers.Publication Pro-Oxidant Activity of Amine-Pyridine-Based Iron Complexes Efficiently Kills Cancer and Cancer Stem-Like Cells(Public Library of Science (PLOS), 2015-09-14) Gonzalez-Bartulos, Marta; Aceves-Luquero, Clara; Qualai, Jamal; Cusso, Olaf; Angeles Martinez, Ma; Fernandez de Mattos, Silvia; Menendez, Javier A; Villalonga, Priam; Costas, Miquel; Ribas, Xavi; Massaguer, AnnaDifferential redox homeostasis in normal and malignant cells suggests that pro-oxidant-induced upregulation of cellular reactive oxygen species (ROS) should selectively target cancer cells without compromising the viability of untransformed cells. Consequently, a pro-oxidant deviation well-tolerated by nonmalignant cells might rapidly reach a cell-death threshold in malignant cells already at a high setpoint of constitutive oxidative stress. To test this hypothesis, we took advantage of a selected number of amine-pyridine-based Fe (II) complexes that operate as efficient and robust oxidation catalysts of organic substrates upon reaction with peroxides. Five of these Fe(II)-complexes and the corresponding aminopyridine ligands were selected to evaluate their anticancer properties. We found that the iron complexes failed to display any relevant activity, while the corresponding ligands exhibited significant antiproliferative activity. Among the ligands, none of which were hemolytic, compounds 1, 2 and 5 were cytotoxic in the low micromolar range against a panel of molecularly diverse human cancer cell lines. Importantly, the cytotoxic activity profile of some compounds remained unaltered in epithelial-to-mesenchymal (EMT)-induced stable populations of cancer stem-like cells, which acquired resistance to the well-known ROS inducer doxorubicin. Compounds 1, 2 and 5 inhibited the clonogenicity of cancer cells and induced apoptotic cell death accompanied by caspase 3/7 activation. Flow cytometry analyses indicated that ligands were strong inducers of oxidative stress, leading to a 7-fold increase in intracellular ROS levels. ROS induction was associated with their ability to bind intracellular iron and generate active coordination complexes inside of cells. In contrast, extracellular complexation of iron inhibited the activity of the ligands. Iron complexes showed a high proficiency to cleave DNA through oxidative-dependent mechanisms, suggesting a likely mechanism of cytotoxicity. In summary, we report that, upon chelation of intracellular iron, the pro-oxidant activity of amine-pyrimidine-based iron complexes efficiently kills cancer and cancer stem-like cells, thus providing functional evidence for an efficient family of redox-directed anti-cancer metallodrugs.