Environmental and Molecular Mutagenesis - Legacy Tobacco ...

141
CORRELATION BETWEEN CHROMOSOME ABERRATION FREQUENCY AND SMALL-COLONY TK-DEFICIENT
MUTANT FREQUENCY IN L5178Y/TK+/- -3 .7 .2C CELLS. C .L . Doerrl and M .M . Moore2 .
lEnvironmental Health Research and Testing, Inc ., Research Triangle Park, NC 27709
USA ; 2U .S . Environmental Potection Agency, Research Triangle Park, NC 27711 USA .
The L5178Y mouse lymphoma assay quantitates gene mutation at ths thymidine kinase
locus . Karyotypic and molecular analyses of mutants have shown an association
between small-colony phenotype and chromosomal events . We have bean evaluating the
association of small-colony induction with gross aberration analysis to determine if
the mouse lymphoma assay can be used directly to determine potential clastogenicity
of test compounds . Based on data from 36 compounds, we find a clear association
between clastogenicity and small-colony induction . There is, as expected, no simple
mathematical correlation between the two endpoints . Many gross aberrations are
incompatible with cell survival and colony formation, and some small-colony TK
mutants are products of events which cannot be scored visually as chromosome
aberrations when small changes in some essential DNA sequence(s) results in slow
growth . Based on these analyses and previous studies, we fsel that the small-colony
TK mutant frequency is the most useful measure of the clastogenicity of test
compounds . It reflects cytogenetic events compatible with long-term cell viability,
and these are the types of events important in human disease . (This is an abstract
of a proposed presentation and does not necessarily reflect U .S . EPA policy .)
142
SULFOTRANSFERASE AND SULFATE LEVELS VARY THE ACTIVATION OF2-P.MIW-3-METHYLIMIDA7A(4,5-
f)QUINOLINE (IQ)
P . Dolara, M . Lodovici, P . Grassi
Department of Pharmacology, University of Florence, Viale Morgagni, 65, Florence,Italy
The in vitro binding of 3H-IQ to herring sperm DNA was measured in the presence of
S9 and microsomes from Wistar rat livers . Both S9 and microsomes from control rats
catalyzed DNA binding of IQ, and a considerable increase in binding was observed using
livers from PCB treated animals . DNA binding was totally blocked by pentachlorophenol
and 2,6-dichloronitrophenol, a specific inhibitor of sulfotransferaae . A mod-
est increase in DNA binding was observed with 3'-phosphoadenosine-5'-phosphosulfate .
Incubation of IQ in media with high sulfate concentrations increased DNA binding in
vitro . An increase of IQ binding was also observed in vivo by varying sulfate pools
in rats with the administration of sulfite in drlnking'water . The data demonstrate a
role for sulfotransferase in the activation of IQ, and suggest a possible role of
dietary sulfite in modulating the activation process of IQ .
143
DETERMINATION OF 4-AMINOBIPHENYL HEMOGLOBIN ADDUCTS AS A MEASURE OF ACTIVATION OF
AROMATIC AMINES IN HUMANS
P . Dolara, G . Moneti, M . Salvadori .
Department of Pharmacology, University of Florence, V .le Morgagni, 65, Florence, Italy
The levels of hemoglobin (Rb) adducts of 4-aminobiphenyl (4-ABP) in smokers are a
function of the exposure to cigarette smoke and of the activation of aromatic amines
to reactive metabolites . We measured the Hb adduct of 4-ABP in humans with massspectrometry,
after hydrolysis of Rb and extraction with methylene chloride . Methy-
lene chloride is preferable to hexane, used in published methods, because of better
recovery of 4-ABP . The exposure to cigarette smoke was quantified by measuring the
24 h excretion of a long-lived metabolite of nicotine (cotinine) . Cotinine levels are
poorly correlated with self reported smoking habits . A good correlation was observed
between 24 h cotinine urinary excretion and the levels of 4-ABP adducts to Hb . The
levels of 4-ABP in non-smokers were never inferior to 50 pg/ g Hb
. The correlation of
cotinine urinary levels and 4-ABP adducts to Hb is defined by a line, the slope of
which is a function of metabolic activation of aromatic amines
. The method was applied
to smoking controls and urinary cancer patients and gave a good estimate of the
capability of different subjects to activate aromatic amines .
http://legacy.library.ucsf.edu/tid/clb93d00/pdf
1989 EMS Abstracts 51
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