A. F. McFee

Bio: A. F. McFee is an academic researcher from Oak Ridge Associated Universities. The author has contributed to research in topics: In vivo & Sister chromatid exchange. The author has an hindex of 9, co-authored 23 publications receiving 885 citations.

Assays of three carcinogen/non-carcinogen chemical pairs for in vivo induction of chromosome aberrations, sister chromatid exchanges and micronuclei.

Abstract: Three pairs of structurally similar carcinogenic/ non-carcinogenic chemicals were tested for in vivo genotoxic activity in B6C3F1 mice. The carcinogenic/non-carcinogenic pairs, respectively, were o-toluidine hydrochloride/o-anthranilic acid, 4-chloro-o-phenylenediamine/4-nitro-o-phenylenediamine, and 3-(chloromethyl)pyridine hydrochloride/2-(chloromethyl)pyridine hydrochloride. Bone marrow cells from mice given intraperitoneal injections of up to the maximum tolerated dose were evaluated for chromosomal aberration, sister chromatid exchange, and micronucleus induction, o-anthranilic acid and o-toluidine hydrochloride did not increase the frequency of chromosomal aberrations or micronuclei. o-Toluidine hydrochloride increased the frequency of sister chromatid exchanges in two successive trials, while o-anthranilic acid had a positive effect on sister chromatid exchanges in two of three trials. Both 2-(chloromethyl) and 3-(chloromethyl)pyridine hydrochloride were negative for all three endpoints. Assays for chromosomal aberrations and micronuclei each distinguished between 4-chloro-o-phenylenedi-amine and its non-carcinogenic companion, 4-nitro-o-phenylenediamine. In the aberration test, 4-chloro-o-phenylenediamine produced a few cells with very large numbers of aberrations rather than an even distribution of damage among cells.

The effect of agent treatment time on the induction of sister-chromatid exchanges in mouse bone marrow cells in vivo

Abstract: The effect of time of agent administration, via intraperitoneal injection, in the yield of SCEs in bone marrow cells of male B6C3F1 mice was determined for cyclophosphamide (CP), 7,12-dimethyl-benz[ a ]-anthracene (DMBA) and mitomycin C (MMC). Animals were treated with several doses of each carcinogen/mutagen at 3 different treatment times: −1, +1 and +8 h in relation to the onset of BrdUrd administration. The results of these studies indicate that the optimal treatment time for inducing a maximal SCE response is agent-specific. For CP, the slope of the SCE response was greatest at the +8 h treatment time while the maximal response for DMBA occurred at the −1 h treatment time. For MMC, the slope of the SCE response was independent of treatment time and of the method of bromodeoxyuridine administration (intravenous infusion vs. tablet implantation) but dependent on the laboratory conducting the study (Brookhaven National Laboratory vs. Oak Ridge Associated Universities). Based on the results of these studies, the +1 h acute treatment time is considered optimal for the in vivo cytogenetic evaluation of suspect chemicals for genotoxic activity when bone marrow is used as the target cell population.

Sister-chromatid exchanges: a report of the GENE-TOX program.

Abstract: This paper reviews the ability of a number of chemicals to induce sister-chromatid exchanges (SCEs). The SCE data for animal cells in vivo and in vitro, and human cells in vitro are presented in 6 tables according to their relative effectiveness. A seventh table summarizes what is known about the effects of specific chemicals on SCEs for humans exposed in vivo. The data support the concept that SCEs provide a useful indication of exposure, although the mechanism and biological significance of SCE formation still remain to be elucidated.

The sources, fate, and toxicity of chemical warfare agent degradation products.

Abstract: We include in this review an assessment of the formation, environmental fate, and mammalian and ecotoxicity of CW agent degradation products relevant to environmental and occupational health. These parent CW agents include several vesicants: sulfur mustards [undistilled sulfur mustard (H), sulfur mustard (HD), and an HD/agent T mixture (HT)]; nitrogen mustards [ethylbis(2-chloroethyl)amine (HN1), methylbis(2-chloroethyl)amine (HN2), tris(2-chloroethyl)amine (HN3)], and Lewisite; four nerve agents (O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothioate (VX), tabun (GA), sarin (GB), and soman (GD)); and the blood agent cyanogen chloride. The degradation processes considered here include hydrolysis, microbial degradation, oxidation, and photolysis. We also briefly address decontamination but not combustion processes. Because CW agents are generally not considered very persistent, certain degradation products of significant persistence, even those that are not particularly toxic, may indicate previous CW agent presence or that degradation has occurred. Of those products for which there are data on both environmental fate and toxicity, only a few are both environmentally persistent and highly toxic. Major degradation products estimated to be of significant persistence (weeks to years) include thiodiglycol for HD; Lewisite oxide for Lewisite; and ethyl methyl phosphonic acid, methyl phosphonic acid, and possibly S-(2-diisopropylaminoethyl) methylphosphonothioic acid (EA 2192) for VX. Methyl phosphonic acid is also the ultimate hydrolysis product of both GB and GD. The GB product, isopropyl methylphosphonic acid, and a closely related contaminant of GB, diisopropyl methylphosphonate, are also persistent. Of all of these compounds, only Lewisite oxide and EA 2192 possess high mammalian toxicity. Unlike other CW agents, sulfur mustard agents (e.g., HD) are somewhat persistent; therefore, sites or conditions involving potential HD contamination should include an evaluation of both the agent and thiodiglycol.

Mutagenicity, toxicity and repair of DNA base damage induced by oxidation.

Abstract: Oxidative DNA damage is a major cause of cell death and mutagenesis in all aerobic organisms, and several new oxidative base lesions have been identified in recent years. Improved chemistry for the synthesis of oligonucleotides with modified base residues at defined positions has allowed detailed studies of repair, replication, transcription and mutagenesis at specific lesions in vitro and in vivo. The aim of this review is to present the structure of all the various known oxidised DNA base lesions known to date and to summarise the present knowledge about the mutagenic and toxic effects of oxidised base modifications and their repair.

Opinion of the Scientific Panel on Food Additives, Flavourings, Processing Aids and Materials in Contact with Food

Abstract: SUMMARY The Scientific Panel on Food Additives, Flavourings, Processing Aids and Materials in Contact with Food (the Panel) is asked to advise the Commission on the implications for human health of chemically defined flavouring substances used in or on foodstuffs in the Member States. In particular, the Scientific Panel is asked to evaluate six flavouring substances in the Flavouring Group Evaluation 16, Revision 1 (FGE.16Rev1), using the procedure as referred to in the Commission Regulation (EC) No 1565/2000. These six flavouring substances belong to chemical group 21, Annex I of the Commission Regulation (EC) No 1565/2000. The present Flavouring Group Evaluation deals with six aromatic ketones. None of the six flavouring substances can exist as geometrical or optical isomers. Five of the six flavouring substances are classified into structural class I and one is classified into structural class III. Four of the six flavouring substances in the present group have been reported to occur naturally in a wide range of food items. In its evaluation, the Panel as a default used the Maximised Survey-derived Daily Intake (MSDI) approach to estimate the per capita intakes of the flavouring substances in Europe. However, when the Panel examined the information provided by the European Flavouring Industry on the

Evaluation of the ability of a battery of three in vitro genotoxicity tests to discriminate rodent carcinogens and non-carcinogens: III. Appropriate follow-up testing in vivo

Abstract: There has been much discussion in recent years regarding the most appropriate follow-up testing in vivo when positive results are obtained in vitro but the in vivo micronucleus (MN) test (traditionally the most widely-used test) is negative. Not all rodent carcinogens give positive results in the micronucleus test, and so it has been common practice to include a second in vivo assay such as the unscheduled DNA synthesis (UDS) test. This has proved useful but is usually limited to analysis of rodent (usually rat) liver. With the increased evaluation and use of other in vivo assays, e.g. for transgenic mutations (TG) and DNA damage (Comet assay) it was important to investigate their usefulness. We therefore examined the published in vivo UDS, TG and Comet-assay results for 67 carcinogens that were negative or equivocal in the micronucleus test. Between 30 and 41 chemicals were evaluated in each of the three in vivo tests, with some overlap. In general, the UDS test was disappointing and gave positive results with 50% of the carcinogens, but the Comet assay detected almost 90% of the micronucleus-negative or equivocal carcinogens. This pattern of results was virtually unchanged when the in vitro profile (gene mutagen or clastogen) was taken into account. High sensitivity (ability to detect carcinogens as positive) is only really useful when the specificity (ability to give negative results with non-carcinogens) is also high. Based on small numbers of publications with non-carcinogens, the TG and Comet assays gave negative results with non-carcinogens on 69 and 78% of occasions, respectively. Although further evaluation of the Comet and TG assays, particularly with non-carcinogens, is needed, these data suggest that they both should play a more prominent role in regulatory testing strategies than the UDS test.