Environmental and Molecular Mutagenesis - Legacy Tobacco ...

52 1989 EMS Abstracts
Notes
http://legacy.library.ucsf.edu/tid/clb93d00/pdf
144
COMPARATIVE STUDIES* ON THE GENOTORIC POTENTIAL OF SIDESTREAN SMOKE FROM CIGARETTES
WHICH BURN OR ONLY HEAT TOBACCO . D . J . Doolittle, C . K . Lee, G . T . Burger and A . V .
Hayes, R . J . Reynolds Tobacco Company, Bowman Gray Technical Center, Winston-Salem,
NC 27102
The in vitro genotoxic activity of sidestream cigarette smoke (SSCS) from cigarettes
which heat but do not burn tobacco was compared to that of SSCS from cigarettes
which burn tobacco . SSCS from five cigarettes were compared . Three of the
cigarettes [the Kentucky reference research cigarette (1R4F), a commercially available
ultra-low tar brand (ULT) and a commercially available ultra-low tar menthol
brand (ULT-menthol)) burn tobacco while two of the cigarettes [a regular (TEST) and a
menthol (TEST-menthol)] heat tobacco . SSCS from all cigarettes was collected by
identical techniques, which involve collecting particulate matter on Cambridge filter
pads and combining with the vapor-phase materials collected by bubbling the smoke
through DHSO . All samples were simultaneously evaluated at identical concentrations
in the test battery . SSCSs from 1R4F . ULT and ULT-menthol cigarettes were positive
in the Ames bacterial mutation assay while TEST and TEST-menthol SSCS was negative .
SSCS from 1R4F, ULT and ULT-menthol cigarettes was positive in the CHO-chromosome
aberration assay and in the CHO-sister chromatid exchange assay while TEST and
TEST-menthol SSCSa were negative in both assays . 1R4F, ULT and ULT-menthol SSCSs
were weakly positive in inducing DNA repair in cultured rat hepatocytes while TEST
and TEST-menthol SSCSs were devoid of activity in this assay . These results demonstrate
that sidestream smoke from the TEST and TEST-menthol cigarettes was not
genotoxic under conditions in which sidestream smoke from 1R4F, ULT and ULT-menthol
cigarettes were genotoxic in a concentration-dependent manner .
145
THE EVOLUTION OF MUTATION RATES : PROSPECTS FOR ANTIMUTAGENESIS .
John W. Drake, Laboratory of Molecular Genetics, National Institute of Environmental
Health Sciences, Research Triangle Park, NC (USA)
Arguments can be adduced for the operation of forces that would either increase or
decrease mutation rates in the course of evolution . In microbial systems, an equilibrium
might be established reflecting the advantages of higher mutation rates that generate
adaptive mutations and the disadvantages of lower mutation rates that generate deleterious
mutations . In more intensively sexual systems, the balance might be between the costs in
time, materials and energy between reducing mutation rates and the costs of bearing the
load of deleterious mutations . Classical experiments bear on both of these possibilities . It
is also likely that antimutagenesis by either genetic modification or pharmaceutical intervention
is a tenuous goal. This notion is superficially contradicted by diverse reports of
antimutator mutations and antimutagenic chemicals, most of which are helpful in understanding
mutational processes but are illusory in promising ways to lower mutation rates in
genetically optimized animal and plant germlines or in higher primates .
146
Comparison of the clastogenic action of mutagens in the presence and
absence of bromodeoxyuridine .
Joachim H . Dresp
Pharmaceutical Research, Department of Toxicology
F . Hoffmann-La Roche i Co . Ltd, CH-4002 Basel, Switzerland
The incorporation of the base analogon bromodeoxyuridine (BrdUrd) into
replicating DNA allows a distinction between cells which are in their
first or second division after initiation of the cell culture .
Up to now the question whether or not the presence of BrdUrd influences
the experimentally induced rate of chromosomal aberrations in human
peripheral lymphocytes cannot be answered unequivocally .
Experiments with different xenobiotics were carried out . The results
illustrate the benefits and the disadvantages of the Brdurd-labelling
technipue .
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