Environmental and Molecular Mutagenesis - Legacy Tobacco ...

190 1989 EMS Abstracts
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Notes •`!'ca1s . In"~e HL system, cells were exposed to the test chemical for
24h and 48h without S9 mix and for 6h with S9 mix . In the CHO system,
cells were eo~or 10 .5-20 .5h without S9 mix and for 2h with S9 mix .
In the absence of S9 mix, 6(24%) out of 25 test chemicals showed diffarent
results : 4 were positive only in CHL, 2 were positive only in CHO .
In the presence of S9 mix, 11(44%) chemicals showed different resultss
8 were positive only in CHL, 3 were positive only in CHO . According
to the combined results with and without S9 mix, 10(40%) showed qualitatively
inconsistent results between two test systems . One of the
reasons for these inconsistent results may be the differences in the
experimental protocol used . However, a possibility that, even by the
same experimental protocol, chromosome aberration induction by some
chemicals miqht be qualitatively and/or quantitatively different
between the CHL and CHO cell systems, still remains .
http://legacy.library.ucsf.edu/tid/clb93d00/pdf
551
FURTHER CHARACTERIZATION OF A METHYL IigTRANESULFONATE-RESISTANT MUTANT FROM A CHINESE
HAMSTER CELL LINE : ANALYSIS OF ITS HYPERSENSITIVITY TO UV
A . Sono and K . Sakaguchi
Division of Toxicology, Research Center, TOYO JOZO Co . Ltd .(Japan) and Department of
Genetics, University of California, Davis(USA)
A Chinese hamster mutant which was highly resistant to methyl mefhanesulfonate (MfS),
referred to as lQ1Sr-1, was found to be hypersensitive to UV . 141S -1 was twice higher
sensitivity to UV in cell killing than the parental line (Don D-6) . The increase was
S-phase specific in the cell cycle . Ca€feine could enhance the UV-lethality of Don
D-6 . However, the survival curve of NMS -1, irrespective of the presence of caffeine,
was almost the same as that for Don D-6 with caffeine . The mutant might be deficient
in post-replicational repair . It also accompanied with higher induction rate of
sister-chromatid exchange (SCE) and chromosomal aberration . The UV-lethality of I41Sr-
1 appeared to relate to the increase rate of lethal chromosomal aberrations, such as
chromatid breaks and exchanges . Although inhibition of protein synthesis enhanced the
hypersensitivity to UV and reduced the acquired resistancy to HHS, it could antagonize
the induction of UV-induced SCE . Inhibition of DNA synthesis affected synergistically
only on the UV-lethality . At the 502 lethal dose of tN, MMSr-1 was unexpectedly much
less mutable than Don D-6 . This phenomenon makes it very difficult to explain only by
a defect in the post-replicational repair system, but may be explanable by adding
another system defect, so called "error-prone repair" which is known only in E . coli .
From these facts, the possible defective feature for this mutant was discussed .
PRCBIEbS Il1 CYTOGENE'PIC SCIIZVEIISd1PKE OF PECPLE '
Sorsa, M ., institute of Occupatiorlal Health, Helsinki, FINIAND
552
Sanatic chrmrosanle damage has been used for some deosdes already as indicator
of exposure of specific grotlps of humans to clastogenic or genotoxic agents . The
niain rationale in the approach is that dmmsge ebserved in the genetic material of
human cells represents or reflects initial events in a process, which may eventually
lead to ill health manifestations . lhus cytoyenetic surveillance has the potential
to serve as an early indicator, enabling prevention of adverse effects .
Several krowm and unoontrollable confoiuti3ers have been reoorded in population
studies ; with proper preplanning most of these can be avoided . Since cytogenetic
biamonitorin3 studies are always tedious and difficult, experimental identification
of the ahrvnceane damaginy potential of the exposing agent(s) must be considered a
prereyuisite to their performance .
A11 stu3ies concerning humans directly also involve ethical aspects and the
riyht-to-know of the persons giving the saaples . T41e planning stage of the study
should also involve an action design for possible decrease of the exposures of the
yroup, if necessary. Otherwise, the preventive nature of cytiogenetic surveillance
is lost .
553
SUB-LETHAL ACIDIFICATION : ITS ROLE IN CHRONIC HEALTH EFFECTS .
C .L . Soskolne ; 0 . Pagano, and 0 .0 . Oiordano, Istituto Nazionale Tumori, 80131 Naples .
Italy, and •University of Alberta, Edmonton, Canada T60 203 .
Mineral acids in the workplace, ae well aa in the general environment represent
a recognized health concern as yet mainly focussed on lethal or acute outcomes .
Over the past decade, long-term workplace exposure to high concentrations of sulfuric
and other acid miste have been shown to be associated with respiratory tract cancers,
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