ABSTRACT
In Costa Rica, <10% of wastewater is treated before its discharge. This generates a significant impact on the environment, public health, and tourism industry, which is one of the country's main economic activities. Biogardens, subsurface flow artificial wetlands, are alternative systems for the treatment of wastewater. The present study evaluated the removal of organic matter and nutrients in a biogarden located at a hotel in the Central Pacific Coast of Costa Rica between 2012 and 2017. Pretreatment involved septic tanks and grease traps for sewage and gray water, respectively. The biogarden, which is composed of seven wetlands with an average area of 12â¯m2 and a depth of 0.7â¯m, contains river cobble as support material, gravel as bed, and Cyperus papyrus and Heliconia sp. plants. Removal of the biochemical oxygen demand (BOD), the chemical oxygen demand (COD), and the total suspended solids (TSS) on average were 80%, 66%, and 72%, respectively, thus producing an effluent in compliance with current national legislation. Furthermore, the biogarden did not emit noxious odors or display an excessive presence of mosquitoes. The results showed consistent and efficient removal of organic matter and nutrients from the wastewater throughout different seasons and pollutant loads, verifying that such systems can be used in decentralized locations (e.g., tourist areas) in tropical climates.
Subject(s)
Waste Disposal, Fluid/methods , Wastewater/analysis , Water Pollutants, Chemical/analysis , Wetlands , Biodegradation, Environmental , Costa Rica , Tropical ClimateABSTRACT
Despite significant progress in the treatment of cancer, there remains an urgent need for more effective therapies that also have less impact on patient wellbeing. Photodynamic therapy employs targeted light activation of a photosensitizer in selected tissues, thereby reducing off-target toxicity. Our group previously reported a RuII ,RhIII bimetallic architecture that displays multifunctional covalent photomodification of DNA in the therapeutic window in an oxygen-independent manner, features that are essential for treating deep and hypoxic tumors. Herein, we explore the mechanism by which a new analogue, [(phen)2 Ru(dpp)Rh(phen)Cl2 ]3+ , or RuII -RhIII , interacts with DNA. We established that RuII -RhIII exhibits "light switch" behavior in the presence of DNA, undergoing strong electrostatic interactions that might involve groove binding. Furthermore, these noncovalent interactions play a major role in the covalent photobinding and photocleavage of DNA, which occur according to an oxygen-independent mechanism. Polymerase chain reaction (PCR) revealed that covalent modification of DNA by RuII -RhIII , especially photobinding, is critical to inhibiting amplification, thus suggesting that the complex could exert its toxic activity by interfering with DNA replication in cells. This new structural motif, with phenanthroline at all three terminal ligand positions, has a number of properties that are promising for the continued refinement of photodynamic-therapy strategies.
Subject(s)
Antineoplastic Agents/chemistry , DNA , Neoplasms/drug therapy , Photochemotherapy , Photosensitizing Agents/chemistry , Rhodium , Ruthenium , DNA/chemistry , DNA/drug effects , Humans , Light , Oxygen/metabolism , Photolysis , Rhodium/chemistry , Rhodium/metabolism , Rhodium/therapeutic use , Ruthenium/chemistry , Ruthenium/metabolism , Ruthenium/therapeutic use , Tumor Hypoxia/drug effectsABSTRACT
In vitro cytotoxicity tests allow for fast and inexpensive screening of drug efficacy prior to in vivo studies. The resazurin assay (commercialized as Alamar Blue®) has been extensively utilized for this purpose in 2D and 3D cell cultures, and high-throughput screening. However, improper or lack of assay validation can generate unreliable results and limit reproducibility. Herein, we report a detailed protocol for the optimization of the resazurin assay to determine relevant analytical (limits of detection, quantification, and linear range) and biological (growth kinetics) parameters, and, thus, provide accurate cytotoxicity results. Fine-tuning of the resazurin assay will allow accurate and fast quantification of cytotoxicity for drug discovery. Unlike more complicated methods (e.g., mass spectrometry), this assay utilizes fluorescence spectroscopy and, thus, provides a less costly alternative to observe changes in the reductase proteome of the cells.
Subject(s)
Biological Assay/methods , Drug Discovery/methods , Drug Evaluation, Preclinical/methods , Indicators and Reagents/chemistry , Oxazines/chemistry , Xanthenes/chemistry , Animals , Cell Line , Cell Survival/drug effects , Humans , Oxidoreductases/analysis , Oxidoreductases/chemistry , Proteome/analysis , Reproducibility of Results , Spectrometry, FluorescenceABSTRACT
The mixed-metal supramolecular complex, [(Ph2phen)2Ru(dpp)PtCl2]2+, displays significant DNA modification, cell growth inhibition, and toxicity towards F98 malignant glioma cells following visible light irradiation. The design of this complex affords superior cellular uptake and antiproliferative activity compared to the classic chemotherapeutic agent, cisplatin.
Subject(s)
Antineoplastic Agents/chemistry , Antineoplastic Agents/pharmacology , Glioma/pathology , Organometallic Compounds/chemistry , Organometallic Compounds/pharmacology , Platinum/chemistry , Ruthenium/chemistry , Animals , Cell Line, Tumor , Cell Proliferation/drug effects , Cell Proliferation/radiation effects , Light , Models, Molecular , Molecular Conformation , RatsABSTRACT
Appending anthracene units to [(bpy)2Ru(dpp)](2+) results in Ru(II) agents that exhibit dynamic photoreactivity towards DNA and protein. [(Anthbpy)(bpy)Ru(dpp)](2+) and [(Anthbpy)2Ru(dpp)](2+) are the first metal-organic Ru(II) agent with dpp ligands shown to photomodify DNA in the presence or absence of oxygen, while also binding protein in an oxygen-dependent manner.
