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Proceedings of the National Academy of... Sep 2019
Topics: DNA Transposable Elements; HSP70 Heat-Shock Proteins; Molecular Chaperones; Mutagenicity Tests; Mutagens
PubMed: 31434787
DOI: 10.1073/pnas.1912725116 -
Ten factors for considering the mode of action of Cr(VI)-induced gastrointestinal tumors in rodents.Mutation Research. Genetic Toxicology... Nov 2017The determination of whether a chemical induces a specific cancer through a mutagenic or non-mutagenic mode of action (MOA) plays an important role in choosing between... (Review)
Review
The determination of whether a chemical induces a specific cancer through a mutagenic or non-mutagenic mode of action (MOA) plays an important role in choosing between linear and nonlinear low-dose extrapolation to derive toxicity criteria. There is no formal framework from the U.S. EPA for determining whether environmental chemicals act through a mutagenic or non-mutagenic MOA; consequently, most such determinations are made on an ad hoc basis. Eastmond [Mutat Res 751 (2012)] recently conducted a systematic investigation of MOA determinations by U.S. and international regulatory agencies and organizations, and identified ten major factors that influence them, including toxicokinetics, in vivo genotoxicity in target organs, data quality, and evidence for alternative MOAs. We have used these ten factors to evaluate mutagenic vs. non-mutagenic MOA for gastrointestinal tumors induced by oral exposure to hexavalent chromium [Cr(VI)]. We also highlight similarities between Cr(VI) and other intestinal carcinogens previously determined to have non-genotoxic MOAs. Based on these analyses, we conclude that the MOA for Cr(VI) induced gastrointestinal tumors is non-mutagenic and that threshold risk assessment approaches are appropriate.
Topics: Animals; Chromium; DNA Damage; Disease Models, Animal; Gene Expression Profiling; Intestinal Neoplasms; Mice; Mutagenesis; Mutagenicity Tests; Mutagens; Reproducibility of Results; Risk Assessment; Toxicokinetics; United States; United States Environmental Protection Agency
PubMed: 28985946
DOI: 10.1016/j.mrgentox.2017.08.004 -
Archives of Toxicology Sep 2022Methyl acrylate (MA) and ethyl acrylate (EA) had previously tested positive for mutagenicity in vitro, but in vivo studies were negative. One of the metabolism pathways...
Methyl acrylate (MA) and ethyl acrylate (EA) had previously tested positive for mutagenicity in vitro, but in vivo studies were negative. One of the metabolism pathways of alkyl acrylates is conjugation with glutathione. The glutathione availability is restricted in standard in vitro test systems so that they do not reflect the in vivo metabolism in this respect. We investigated whether the addition of glutathione to the in vitro L5178Y/TK mouse lymphoma mutagenicity test prevents alkyl acrylate's mutagenicity in vitro. We also investigated whether the quantitative relationships support the notion that the GSH supplemented in vitro systems reflect the true in vivo activity. Indeed, glutathione concentrations as low as 1 mM completely negate the mutagenicity of MA and EA in the L5178Y/TK mouse lymphoma mutagenicity test up to the highest concentrations of the two acrylates tested, 35 µg/ml, a higher concentration than that previously found to be mutagenic in this test (14 µg MA/ml and 20 µg EA/ml). 1 mM Glutathione reduced the residual MA and EA at the end of the exposure period in the mutagenicity tests by 96-97%, but in vivo up to 100 mg/kg body weight MA and EA left the glutathione levels in the mouse liver and forestomach completely intact. It is concluded that the in-situ levels of glutathione, 7.55 ± 0.57 and 2.84 ± 0.22 µmol/g mouse liver and forestomach, respectively, can efficiently protect against MA and EA-induced mutagenicity up to the high concentration of 100 mg MA and EA/kg body weight and that the negative in vivo mutagenicity tests on MA and EA reflect the true in vivo situation.
Topics: Acrylates; Animals; Body Weight; Glutathione; Lymphoma; Mice; Mutagenicity Tests; Mutagens
PubMed: 35704047
DOI: 10.1007/s00204-022-03322-1 -
Scientific Reports May 2022Synacinn is a standardized polyherbal extract formulated for the treatment of diabetes mellitus and its complications. This study aims to assess the mutagenicity...
Synacinn is a standardized polyherbal extract formulated for the treatment of diabetes mellitus and its complications. This study aims to assess the mutagenicity potential of Synacinn by Ames assay and in vivo bone marrow micronucleus (MN) test on Sprague Dawley rat. Human ether-a-go-go-related gene (hERG) assay and Functional Observation Battery (FOB) were done for the safety pharmacology tests. In the Ames assay, Dose Range Finding (DRF) study and mutagenicity assays (+/- S9) were carried out. For the MN test, a preliminary and definitive study were conducted. In-life observations and number of immature and mature erythrocytes in the bone marrow cells were recorded. The hERG assay was conducted to determine the inhibitory effect on hERG potassium channel current expressed in human embryonic kidney cells (HEK293). FOB tests were performed orally (250, 750, and 2000 mg/kg) on Sprague Dawley rats. Synacinn is non-mutagenic against all tested strains of Salmonella typhimurium and did not induce any clastogenicity in the rat bone marrow. Synacinn also did not produce any significant inhibition (p ≤ 0.05) on hERG potassium current. Synacinn did not cause any neurobehavioural changes in rats up to 2000 mg/kg. Thus, no mutagenicity, cardiotoxicity and neurotoxicity effects of Synacinn were observed in this study.
Topics: Animals; HEK293 Cells; Humans; Hypoglycemic Agents; Mutagenicity Tests; Mutagens; Rats; Rats, Sprague-Dawley
PubMed: 35505003
DOI: 10.1038/s41598-022-11243-3 -
Scientific Reports Oct 2023Concerns have recently increased that the integrity of some scientific research is questionable due to the inability to reproduce the claimed results of some experiments...
Concerns have recently increased that the integrity of some scientific research is questionable due to the inability to reproduce the claimed results of some experiments and thereby confirm that the original researcher's conclusions were justified. This phenomenon has been described as 'reproducibility crisis' and affects various fields from medicine to basic applied sciences. In this context, the REPLICA project aims to replicate previously conducted in vitro studies on the toxicity of cigarette smoke and e-cigarette aerosol, sometimes adding experiments or conditions where necessary, in order to verify the robustness and replicability of the data. In this work the REPLICA Team replicated biological and toxicological assessment published by Rudd and colleagues in 2020. As in the original paper, we performed Neutral Red Uptake (NRU) assay for the evaluation of cytotoxicity, Ames test for the evaluation of mutagenesis and In Vitro Micronuclei (IVMN) assay for the evaluation of genotoxicity on cells treated with cigarette smoke or e-cigarette aerosol. The results showed high cytotoxicity, mutagenicity and genotoxicity induced by cigarette smoke, but slight or no cytotoxic, mutagenic and genotoxic effects induced by the e-cigarette aerosol. Although the two studies presented some methodological differences, the findings supported those previously presented by Rudd and colleagues.
Topics: Mutagens; Electronic Nicotine Delivery Systems; Cigarette Smoking; Reproducibility of Results; Nicotiana; Mutagenesis; DNA Damage; Aerosols; Mutagenicity Tests
PubMed: 37903810
DOI: 10.1038/s41598-023-44626-1 -
Environmental and Molecular Mutagenesis Jun 2017
Topics: Carcinogenesis; Humans; Mutagenicity Tests; Mutagens
PubMed: 28621032
DOI: 10.1002/em.22106 -
Mutation Research. Genetic Toxicology... 2020This work investigates a completely novel and experimental concept of exposing L5178Y cells at the air-agar-interface to mainstream cigarette smoke aerosol (Kentucky...
This work investigates a completely novel and experimental concept of exposing L5178Y cells at the air-agar-interface to mainstream cigarette smoke aerosol (Kentucky reference 3R4F). This study highlights the associated challenges of combining a suspension cell line alongside an in vitro aerosol exposure system. To achieve a monolayer, cells were 'seeded' in a concentrated cell super-mix suspension onto an RPMI/agar-matrix -base. The resulting cell suspension media was adsorbed into the agar base leaving the L5178Y cells lightly suspended on the agar surface, approximating a monolayer. Cells were deemed supportable on the agar-matrix, viable and recoverable. Using Vitrocell VC 10 exposure system and the Ames 4 exposure module, L5178Y cells were successfully exposed to a dynamic cigarette smoke aerosol, recovered and assessed for mutant frequencies, using standard assay procedures. Method development included assessment of flowing air conditions, plating efficiency and recovery of L5178Y cells from the agar-matrix surface. Positive controls MMS and B[a]P were successfully incorporated into the agar-matrix and metabolic activation was achieved by S-9 incorporation into the same agar-base-matrix. B[a]P demonstrated metabolic activation and positive response, suggesting a clear cellular interaction with the agar-matrix. Whole smoke exposed cells in the presence of metabolic activation showed a clear dose response and increasing mutant frequencies, well in excess of the controls (air and incubator) and the global evaluation factor following a 2 or 3 day expression period. This experimental concept demonstrates that L5178Y cells can be exposed to cigarette smoke aerosol, using a completely novel and a previously untested approach. Although this work successfully demonstrates the approach is viable and cells can be plated and maintained on an agar-matrix, more optimisation and robustness assessment is required before it can be considered fully adapted and used alongside other whole aerosol methodologies for the assessment of cigarette smoke and other inhaled aerosols.
Topics: Aerosols; Agar; Air; Animals; Cell Line; Dose-Response Relationship, Drug; Electronic Nicotine Delivery Systems; Humans; Lymphoma; Mice; Mutagenicity Tests; Mutagens; Smoke
PubMed: 32928375
DOI: 10.1016/j.mrgentox.2020.503230 -
Environmental Health Perspectives Oct 1994Mutagenic heterocyclic amines are generated in foods when they are cooked at temperatures over 150 degrees C. These compounds are present from 0.1 to 50 ppb, depending... (Review)
Review
Mutagenic heterocyclic amines are generated in foods when they are cooked at temperatures over 150 degrees C. These compounds are present from 0.1 to 50 ppb, depending on the food and cooking conditions. These heterocyclic amines are not only present in cooked red meat, fish, and chicken, but are also present at lower levels in baked and fried foods derived from grain. Mutagenicity of fried beef hamburgers cooked at 230 degrees C is 800 +/- 37 TA98 revertants per gram cooked weight. We measured 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MelQx), 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline (DiMelQx), and 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) formation at this temperature and found 3.0 +/- 2.0, 1.0 +/- 0.18, and 0.06 +/- 0.03 ng/g, respectively. 2-amino-1-methyl-6-phenylimidaz[4,5-b]pyridine (PhIP) was found at a higher concentration of 9.6 ng/g. In our laboratory we have shown these heterocyclic amines are capable of producing both reverse and forward mutations in Salmonella bacteria and forward mutations in Chinese hamster ovary cells (CHO). We have also been able to show a statistically significant increase in mutations in the pancreas of the "mutamouse" following PhIP exposure. The pancreas also shows relatively high DNA binding compared to other organs in the mouse. The number and type of mutations depend on the repair capacity of the cells for both Salmonella and CHO. In Salmonella the mutations are primarily 2-base deletions when the cells lack uvrB repair, but mutations are more complex (larger deletions and insertions) but lower in frequency when repair is functional.(ABSTRACT TRUNCATED AT 250 WORDS)
Topics: Amines; Animals; Food Analysis; Food Contamination; Heterocyclic Compounds; Hot Temperature; Mutagens
PubMed: 7889848
DOI: 10.1289/ehp.94102s6201 -
IARC Monographs on the Evaluation of... 1999
Review
Topics: Animals; Carcinogenicity Tests; Carcinogens; Humans; Mutagenicity Tests; Mutagens; Neoplasms, Experimental; Thiophenes
PubMed: 10476378
DOI: No ID Found -
IARC Monographs on the Evaluation of... 1999
Review
Topics: Animals; Carcinogenicity Tests; Carcinogens; Humans; Mutagenicity Tests; Mutagens; Neoplasms; Neoplasms, Experimental; Occupational Exposure; Risk Factors; Sulfuric Acid Esters
PubMed: 10476420
DOI: No ID Found