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Regulatory Toxicology and Pharmacology... Jun 2017Nephure™ is a proprietary oxalate decarboxylase (OxDC) enzyme being developed as a food ingredient. In this study, the safety of Nephure™ was evaluated in a...
Nephure™ is a proprietary oxalate decarboxylase (OxDC) enzyme being developed as a food ingredient. In this study, the safety of Nephure™ was evaluated in a bacterial mutagenicity assay and in a sub-chronic (13-week) oral toxicity study in rats. Nephure™ did not show any mutagenic properties in the mutagenicity assay. In the 13-week sub-chronic oral toxicity study in which 10 Sprague Dawley rats per sex were administered 0, 118, 235 and 475 mg/kg bw/day (8260, 16450 and 33,250 Units/kg bw/day, respectively) of Nephure™ by gavage, male and female rats did not show any test article-related clinical observations or effects on body weight, body weight gain, food consumption, food efficiency, ophthalmology, functional observational battery parameters or motor activity. Furthermore, there were no changes in coagulation, clinical chemistry, urinalysis or hematology parameters, macroscopic/microscopic findings or organ weights that could be attributed to the test article. Based on these results, Nephure™ was not mutagenic and the no-adverse-effect level (NOAEL) in the 13-week study was determined to be 475 mg/kg bw/day (33,250 Units/kg bw/day). Evaluation of the estimated consumption of Nephure™, generation of the metabolite formate, and the current safety studies resulted in a conclusion of a tolerable upper limit of 3450 Units of OxDC activity/day (57.5 Units activity/kg bw/day), when Nephure™ is added to food to decrease dietary oxalate.
Topics: Animals; Body Weight; Female; Male; Mutagenicity Tests; No-Observed-Adverse-Effect Level; Organ Size; Rats; Rats, Sprague-Dawley; Time Factors; Toxicity Tests, Subchronic
PubMed: 28322893
DOI: 10.1016/j.yrtph.2017.03.016 -
PloS One 2017An increasing number of industrial, agricultural and commercial chemicals in the aquatic environment lead to various deleterious effects on organisms, which is becoming...
An increasing number of industrial, agricultural and commercial chemicals in the aquatic environment lead to various deleterious effects on organisms, which is becoming a serious global health concern. In this study, the Ames test and SOS/umu test were conducted to investigate the potential genotoxicity and mutagenicity caused by organic extracts from drinking water sources. Organic content of source water was extracted with XAD-2 resin column and organic solvents. Four doses of the extract equivalent to 0.25, 0.5, 1 and 2L of source water were tested for toxicity. All the water samples were collected from six different locations in Guangdong province. The results of the Ames test and SOS/umu test showed that all the organic extracts from the water samples could induce different levels of DNA damage and mutagenic potentials at the dose of 2 L in the absence of S9 mix, which demonstrated the existence of genotoxicity and mutagenicity. Additionally, we found that Salmonella typhimurium strain TA98 was more sensitive for the mutagen. Correlation analysis between genotoxicity, Organochlorine Pesticides (OCPs) and Polycyclic Aromatic Hydrocarbons (PAHs) showed that most individual OCPs were frame shift toxicants in drinking water sources, and there was no correlation with total OCPs and PAHs.
Topics: China; Drinking Water; Mutagenesis; Mutagenicity Tests; Mutagens; Pesticides; Salmonella typhimurium; Water Pollutants, Chemical
PubMed: 28125725
DOI: 10.1371/journal.pone.0170454 -
Mutation Research 2009Higher plants are recognized as excellent genetic models to detect environmental mutagens and are frequently used in monitoring studies. Among the plant species, Alium... (Review)
Review
Higher plants are recognized as excellent genetic models to detect environmental mutagens and are frequently used in monitoring studies. Among the plant species, Alium cepa has been used to evaluate DNA damages, such as chromosome aberrations and disturbances in the mitotic cycle. Employing the A. cepa as a test system to detect mutagens dates back to the 40s. It has been used to this day to assess a great number of chemical agents, which contributes to its increasing application in environmental monitoring. The A. cepa is characterized as a low cost test. It is easily handled and has advantages over other short-term tests that require previous preparations of tested samples, as well as the addition of exogenous metabolic system. Higher plants, even showing low concentrations of oxidase enzymes and a limitation in the substrate specification in relation to other organism groups, present consistent results that may serve as a warning to other biological systems, since the target is DNA, common to all organisms. The A. cepa test also enables the evaluation of different endpoints. Among the endpoints, chromosome aberrations have been the most used one to detect genotoxicity along the years. The mitotic index and some nuclear abnormalities are used to evaluate citotoxicity and analyze micronucleus to verify mutagenicity of different chemicals. Moreover, the A. cepa test system provides important information to evaluate action mechanisms of an agent about its effects on the genetic material (clastogenic and/or aneugenic effects). In the face of all the advantages that the A. cepa test system offers, it has been widely used to assess the impacts caused by xenobiotics, characterizing an important tool for environmental monitoring studies, where satisfactory results have been reported.
Topics: Chromosome Aberrations; Environmental Monitoring; Environmental Pollutants; Micronucleus Tests; Mitotic Index; Mutagenicity Tests; Mutagens; Onions; Sensitivity and Specificity
PubMed: 19577002
DOI: 10.1016/j.mrrev.2009.06.002 -
Mutation Research. Genetic Toxicology... May 2015This workshop reviewed the current science to inform and recommend the best evidence-based approaches on the use of germ cell genotoxicity tests. The workshop questions... (Review)
Review
This workshop reviewed the current science to inform and recommend the best evidence-based approaches on the use of germ cell genotoxicity tests. The workshop questions and key outcomes were as follows. (1) Do genotoxicity and mutagenicity assays in somatic cells predict germ cell effects? Limited data suggest that somatic cell tests detect most germ cell mutagens, but there are strong concerns that dictate caution in drawing conclusions. (2) Should germ cell tests be done, and when? If there is evidence that a chemical or its metabolite(s) will not reach target germ cells or gonadal tissue, it is not necessary to conduct germ cell tests, notwithstanding somatic outcomes. However, it was recommended that negative somatic cell mutagens with clear evidence for gonadal exposure and evidence of toxicity in germ cells could be considered for germ cell mutagenicity testing. For somatic mutagens that are known to reach the gonadal compartments and expose germ cells, the chemical could be assumed to be a germ cell mutagen without further testing. Nevertheless, germ cell mutagenicity testing would be needed for quantitative risk assessment. (3) What new assays should be implemented and how? There is an immediate need for research on the application of whole genome sequencing in heritable mutation analysis in humans and animals, and integration of germ cell assays with somatic cell genotoxicity tests. Focus should be on environmental exposures that can cause de novo mutations, particularly newly recognized types of genomic changes. Mutational events, which may occur by exposure of germ cells during embryonic development, should also be investigated. Finally, where there are indications of germ cell toxicity in repeat dose or reproductive toxicology tests, consideration should be given to leveraging those studies to inform of possible germ cell genotoxicity.
Topics: Animals; DNA Mutational Analysis; Education; Genome-Wide Association Study; Germ Cells; Germ-Line Mutation; High-Throughput Nucleotide Sequencing; Humans; Mutagenicity Tests; Mutagens; Risk Assessment
PubMed: 25953399
DOI: 10.1016/j.mrgentox.2015.01.008 -
The Journal of Toxicological Sciences Feb 1991Two in vitro tests with different genetic end points, gene mutation and chromosomal damage, and an in vivo test, preferably the micronucleus test in mice, were... (Review)
Review
Two in vitro tests with different genetic end points, gene mutation and chromosomal damage, and an in vivo test, preferably the micronucleus test in mice, were recommended as a battery system for the primary assessment of genotoxic effects of chemicals. From our comparative studies on the mutagenic potency of chemicals, it was pointed out that results should be evaluated quantitatively rather than qualitatively, since the potency varies extensively, at range of 10(7) fold, among different chemicals, and the in vitro genotoxins relatively weak tend to be negative in in vivo mutagenicity tests as well as in carcinogenicity tests in rodents. New Salmonella tester strains, called YG-series, were established, which showed a high nitroreductase or acetyltransferase activity and specifically sensitive to nitroarens or aromatic anmines in the reverse mutation assays (Ames test). These strains could detect a small amount of mutagenic aromatic amines containing in the urine of cigarette smokers. A new technique in the micronucleus test using peripheral blood erythrocytes was introduced. A cumurative genotoxic effect of benzene, for an example, was detected in the peripheral blood even several weeks after treatment every week by gavage. A cyto-flowmetric analysis can be also applied to monitoring of such effects.
Topics: Animals; Humans; Mutagenicity Tests; Mutagens
PubMed: 1920547
DOI: 10.2131/jts.16.supplementi_83 -
BMC Pharmacology & Toxicology Jan 2022Py-mulin is a new pleuromutilin derivative with potent antibacterial activities in vitro and in vivo, suggesting this compound may lead to a promising antibacterial drug...
BACKGROUND
Py-mulin is a new pleuromutilin derivative with potent antibacterial activities in vitro and in vivo, suggesting this compound may lead to a promising antibacterial drug after further development. The present study is aimed to evaluate the acute and subacute oral toxicity, and the genotoxicity with the standard Ames test according to standard protocols.
METHODS
Acute oral toxicity of Py-mulin was determined using Kunming mice. The 28-day repeated dose oral toxicity study in SD rats was performed according to OECD guideline No. 407. The bacterial reverse mutation (Ames test) was carried out using four Salmonella typhimurium (S. typhimurium) strains TA97, TA98, TA100 and TA1535 with and without S9 metabolic activation.
RESULTS
The LD values in acute oral toxicity were 2973 mg/kg (female mice) and 3891 mg/kg (male mice) calculated by the Bliss method. In subacute toxicity study, 50 mg/kg Py-mulin did not induce any abnormality in body weight, food consumption, clinical sign, hematology, clinical chemistry, organ weight, and histopathology in all of the treatment groups. However, high doses of Py-mulin (100 and 300 mg/kg) displayed slightly hepatotoxicity to female rats. Furthermore, Py-mulin did not significantly increase the number of revertant colonies of four standard S. typhimurium strains with the doses of 0.16-1000 μg/plate in the Ames study.
CONCLUSIONS
Based on our findings, our study provides some information for the safety profile of Py-mulin.
Topics: Animals; Anti-Bacterial Agents; Female; Lethal Dose 50; Male; Mice; Mutagenicity Tests; Rats; Rats, Sprague-Dawley; Salmonella typhimurium
PubMed: 34983673
DOI: 10.1186/s40360-021-00543-5 -
Stem Cells Translational Medicine Mar 2020Three-dimensional biofabrication using photo-crosslinkable hydrogel bioscaffolds has the potential to revolutionize the need for transplants and implants in joints, with... (Review)
Review
Three-dimensional biofabrication using photo-crosslinkable hydrogel bioscaffolds has the potential to revolutionize the need for transplants and implants in joints, with articular cartilage being an early target tissue. However, to successfully translate these approaches to clinical practice, several barriers must be overcome. In particular, the photo-crosslinking process may impact on cell viability and DNA integrity, and consequently on chondrogenic differentiation. In this review, we primarily explore the specific sources of cellular cytotoxicity and genotoxicity inherent to the photo-crosslinking reaction, the methods to analyze cell death, cell metabolism, and DNA damage within the bioscaffolds, and the possible strategies to overcome these detrimental effects.
Topics: Cartilage, Articular; Cell Differentiation; Cytotoxicity Tests, Immunologic; Humans; Hydrogels; Mutagenicity Tests; Tissue Scaffolds
PubMed: 31769213
DOI: 10.1002/sctm.19-0192 -
Mutation Research. Genetic Toxicology... Oct 2019Bruce Ames has had an enormous impact on human health by developing facile methods for the identification of mutagens. This research also provided important insights...
Bruce Ames has had an enormous impact on human health by developing facile methods for the identification of mutagens. This research also provided important insights into the relationship between mutagenesis and carcinogenesis. Bruce is a highly innovative and creative individual who has followed his interests across disciplines into diverse fields of inquiry. The present author had the pleasure of spending a sabbatical in the Ames lab and utilized the Ames test in multiple aspects of his research. He describes both in this honorific to Bruce on the occasion of his 90 birthday.
Topics: Activation, Metabolic; Animals; Biochemistry; California; Genetics; History, 20th Century; History, 21st Century; Microsomes, Liver; Molecular Structure; Mutagenesis; Mutagenicity Tests; Mutagens; Rats; Rats, Sprague-Dawley; Salmonella
PubMed: 31585632
DOI: 10.1016/j.mrgentox.2019.06.006 -
Mutation Research. Genetic Toxicology... Oct 2022The potential genotoxicity of titanium dioxide (TiO) nanoparticles (NPs) is a conflictive topic because both positive and negative findings have been reported. To add...
The potential genotoxicity of titanium dioxide (TiO) nanoparticles (NPs) is a conflictive topic because both positive and negative findings have been reported. To add clarity, we have carried out a study with two cell lines (V79-4 and A549) to evaluate the effects of TiO NPs (NM-101), with a diameter ranging from 15 to 60 nm, at concentrations 1-75 μg/cm. Using two different dispersion procedures, cell uptake was determined by Transmission Electron Microscopy (TEM). Mutagenicity was evaluated using the Hprt gene mutation test, while genotoxicity was determined with the comet assay, detecting both DNA breaks and oxidized DNA bases (with formamidopyrimidine glycosylase - Fpg). Cell internalization, as determined by TEM, shows TiO NM-101 in cytoplasmic vesicles, as well as close to and inside the nucleus. Such internalization did not depend on the state of agglomeration, nor the dispersion used. In spite of such internalization, no cytotoxicity was detected in V79-4 cells (relative growth activity and plating efficiency assays) or in A549 cells (AlamarBlue assay) after exposure lasting for 24 h. However, a significant decrease in the relative growth activity was detected at longer exposure times (48 and 72 h) and at the highest concentration 75 µg/cm. When the modified enzyme-linked alkaline comet assay was performed on A549 cells, although no significant induction of DNA damage was detected, a positive concentration-effects relationship was observed (Spearman's correlation = 0.9, p 0.0001). Furthermore, no significant increase of DNA oxidized purine bases was observed. When the frequency of Hprt gene mutants was determined in V79-4 cells, no increase was observed in the exposed cells, relative to the unexposed cultures. Our general conclusion is that, under our experimental conditions, TiO NM-101 exposure does not exert mutagenic effects despite the evidence of NP uptake by V79-4 cells.
Topics: Comet Assay; DNA; DNA Damage; Hypoxanthine Phosphoribosyltransferase; Metal Nanoparticles; Mutagenicity Tests; Mutagens; Nanoparticles; Purines; Titanium
PubMed: 36155144
DOI: 10.1016/j.mrgentox.2022.503545 -
Toxicology in Vitro : An International... Feb 2018The Salmonella reversion based Ames test is the most widely used method for mutagenicity testing. For rapid toxicity assessment of e.g. water samples and for...
The Salmonella reversion based Ames test is the most widely used method for mutagenicity testing. For rapid toxicity assessment of e.g. water samples and for effect-directed analysis, however, the Ames test suffers from lack of throughput and is regarded as a laborious, time consuming method. To achieve faster analysis, with increased throughput, a (downscaled) luminescent derivative of the Ames Salmonella/microsome fluctuation test has been developed through expression of the Photorhabdus luminescens luciferase in the Salmonella TA98 and TA100 strains. The applicability of this test is demonstrated by analysis of environmentally relevant compounds, a suspended particulate matter extract and an industrial effluent sample. Use of the luminescent reporter reduced the required detection time from 48 to 28h with a specificity of 84% for responses reported in the literature to a set of 14 mutagens as compared to 72% in the unmodified fluctuation test. Testing of the same compounds in a downscaled luminescent format resulted in an 88% similarity with the response found in the regular luminescent format. The increase in throughput, faster analysis and potential for real-time bacterial quantification that luminescence provides, allows future application in the high-throughput screening of large numbers of samples or sample fractions, as required in effect-directed analysis in order to accelerate the identification of (novel) mutagens.
Topics: Industrial Waste; Luciferases, Bacterial; Microsomes; Mutagenicity Tests; Mutagens; Plasmids; Salmonella; Time Factors; Water Pollutants, Chemical; Water Pollution, Chemical
PubMed: 28888659
DOI: 10.1016/j.tiv.2017.09.005