Evaluation of toxicity of medical devices using Spirotox and Microtox tests: I. Toxicity of selected toxicants in various diluents.
ABSTRACT Significant effort has been directed toward developing in vitro alternatives, which can be the first step of toxicity analysis. Tissue culture assays are currently the most popular in vitro tests for evaluating acute toxicity. The possibility of applying two bioassays using microorganisms in assessing the toxicity of extracts of medical devices was investigated. The Microtox test system--a luminescent bacteria toxicity test--assesses changes in light output from a luminescent bacteria, Vibrio fischeri. Spirotox used a large ciliate protozoan: Spirostomum ambiguum. The most widely used extraction solvent, 0.9% NaCl, must be concentrated up to 2% for Microtox and diluted nine times for the Spirotox test. The organic solvents ethanol, DMSO, and polyethylene glycol 400 were not toxic in either test in concentrations of 1-2%. The toxicity of reference compounds Hg, Cd, Zn, Pb, and SDS was examined in various diluents. The sequence of toxicity of the tested compounds in Spirotox and Microtox was: Hg > Cd > Zn > Pb > SDS, and Hg > Pb = Zn > SDS > Cd, respectively. Addition of organic solvents changed the toxicity of compounds tested in 60% of Spirotox tests and only in 25% of Microtox tests. Changes were low, not exceeding 100% in almost all cases. No correlation was observed between diluent and toxicant in either bioassay.
Article: Bioluminescent monitoring of detoxification processes: activity of humic substances in quinone solutions.[show abstract] [hide abstract]
ABSTRACT: This study deals with application of bioluminescent assay systems to evaluate the detoxifying effect of humic substances (HS) on the solutions of organic oxidizers - quinones. A series of homologous quinones with different redox characteristics: 1,4-benzoquinone, tetrafluoro-1,4-benzoquinone, methyl-1,4-benzoquinone, tetramethyl-1,4-benzoquinone, and 1,4-naphtoquinone, was used. Bioluminescent bacteria Photobacterium phosphoreum, and NADH:FMN-oxidoreductase-luciferase enzyme system isolated from these bacteria were used as assay systems. The toxicity was compared in the presence and in the absence of HS. Variation of complexity of bioassays (in vivo or in vitro) combined with spectrometric and microscopic methods, provides insight into the process of detoxification in quinone solutions. Two ways of HS effect were studied: the reduction activity of HS and intensification of self-protection of bacterial cells on HS addition.Journal of Photochemistry and Photobiology B Biology 10/2007; 88(2-3):131-6. · 2.81 Impact Factor
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ABSTRACT: Bioluminescent systems are convenient objects to study mechanisms of influence of exogenous molecules on living organisms. Classification of physical and physico-chemical mechanisms of the effects of luminous bacteria Photobacterium leiognathi on bioluminescent reactions is suggested. Five mechanisms are discussed: (1) change of electron-excited states' population and energy transfer, (2) change of efficiency of S-T conversion in the presence of external heavy atom, (3) change of rates of coupled reactions, (4) interactions with enzymes and variation of enzymatic activity, (5) nonspecific effects of electron acceptors. Effects of various groups of chemical compounds are discussed according to the classification suggested. The compounds are: a series of fluorescent dyes, organic oxidizers, organic and inorganic heavy-atom containing compounds, and metallic salts. Applications of fluorescence time-resolved and steady-state techniques, as well as bioluminescence kinetics study, are discussed. The patterns of exogenous compounds' influence form a physico-chemical basis for bioluminescent ecological assay.Journal of Photochemistry and Photobiology B Biology 05/2006; 83(1):77-86. · 2.81 Impact Factor
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ABSTRACT: The influence of a series of quinones and phenols on bacteria bioluminescence systems was investigated. Three bioluminescence systems used in ecological monitoring were compared: (1) water-soluble; (2) immobilized in starch gel coupled enzyme systems: NADH:FMN-oxidoreductase-luciferase; (3) luminescent bacteria. Bioluminescence inhibition constants of quinones and phenols and bioluminescence induction periods were compared. These kinetic parameters are proportional to quinone concentrations and depend on the quinone redox potential. Different effects of the substances are related to structure and properties of the bioluminescence systems. The set of bioluminescence assays for quinones and phenols monitoring should include two bioluminescence systems: 1 (or 2) and 3.Ecotoxicology and Environmental Safety 11/2002; 53(2):221-5. · 2.29 Impact Factor