Environmental and Molecular Mutagenesis - Legacy Tobacco ...

prevented by ADPRT inhibitors,3-aminobenzamide or nicotinamide,which were shown to
exert no influence on,the NAD lowering due to NAD biosynthesis blockade . (4) In pnaphthoflavon,a
c tocFrome P450 isozyme inducer,induced or unindnced human amnion
FL cells,AFB1,B(a~P,pyrene,2-AAF,9,10-dimethylanthracene and sthylcarbamate could
induce the decrease of cellular NAD mediated by ADPRT aotivation,4-4.LF,anthracene,
isopropyl N-(3-chlorophenyl)-carbamate,(i-propiolactone,Y-butyrolactone,cyclophosphamide
and safrol couldnot . This preliminary validation results indicate that this
new assay is specific for detecting DNA damage with a sensitivity and specificity
at nearly the same grade as well va idated UDS assay with rat liver S9 system for
metabolic activation of p,romutagens~p_rocarcinogens .
659
INITIATION OF CHEMICAL CARCINOGENESIS A ND HYPOMETHYLATION OF CELLULAR DNA REVISITEDe
Y .N .Yu,Z .Z .Shi,and X .R .Chen,Zhejiang Medical University,Hangzhou(China)
•The Project supported by National Natural Science Foundation of China
The extent of enzymatic methylation of newly synthesized DNA labelled with 3H-TdR
prior to harvesting in human amnion FL cell line after carcino en (two nongenotoxic,
5-azacytidine and L-ethionine and two genotoxic, MNNG and AFB1~ exposure wes analyer
ed by the digestibility with restriction endonuclease HpaII . The weight average
lengths (Lw) of HpaII digest of the DNA isolated from the -azacytidin . (2 x 10-6M
1-day exposure, DNA isolated at the 5th day after exposure) and L-ethionine (2 x
10-3M 9-day exposure, DNA isolated at the time of the end of exposure) treated cells
were significantly lower than those of the controle (Lws8 .0 • 0 .1 kb va 10 .9 i 1 .Okb
p< 0 .01 and 9 .8 . 0 .3 kb vs 10 .6 + 0 .3 kb p< 0 .05 respectively) . While those from
the cells exposed to MNNG (5 x 10-6M 1-day exposure, DNA isolated at the 5th day after
treatment and AFB1 (2 .5 x 10-5M 1-day exposure, DNA isolated at the 6th day after
treatment) were not different from those of the controls (Lwt 11 . a 0 .7 kb vs
10 .6 . 0 .8 kb and 10 .6 + 0 .5 kb vs 10 .4 + 0 .7 kb p> 0 .05 respectively~ . Our results
suggest thpt the stable and heritable alteration of inethylatlon patterns in cellular
DNA may be a specific mechanism of carcinogenic initiation by some, but not all
kinds of carcinogens, and the hypomethylation of DNA frequently seen in tumor tissues
may be formed during the process of initiation as well as promotion and/ or progression
phase of carcinogenesis. •
660 "
BACILLUS SUBTILIS RED-ASSAY AND MUTAGENICITY DETECTION OF METAL COMPOUNDS
Wang Yuzhi and Tang Tianbao ; Shenyang Res . Institute of Industrial
Hygiene and Occupational Disease, Shenyang, P .R . CHIA
The bacterial systems have become efficient and sensitive methods
for screening mutagenicity and carcinogenicity of chemical compounds .
in this study, B . subtilis Red-assay was selected to test metal compounds
with Hiran's spore method . The spores of Rec+ and Rec- strains
of B . subtilis were prepared in agar and a paper disk, impregnated
with the chemical solution placed on the surface . After 20 hours incubation
at 37 C, diameters of inhibition zones are measured with each
strain . A difference of -3mm is a positive effect . In order to
compare their sensitivity, the spore and vegetative cell rec-essays
were performed with chmicals and metals with or without S9 metabolic
activation . The results show that use of spores in place of vegetative
cells increased the detective sensitivity 7- to 10-fold . In 24 hours
incubation at 37°C, BeSOq and V205are negative, but in incubation at
4°C for 24 hours and at 37°C for another 20 hours, positive results
are obtained . The B . subtilis spore rec-assay is one of the systems
which is least expensive, rapid and non-laborious .
661
OBSERVATION OF THE EYES IN 53 WORKERS OCCUPATIONALLY EXPOSED TO METHANOL
SuJuan-Zang .
Research Institution of Labour Health Sciences in LiaoNing (China)
The methanol is a solvent of chemical industry . Acute poisoning of
methsnol may injure the nervous systems and the eyes . Harm of the eyes
is retrobulbar optic neuritis, optic neuritis and intraocular neuritis .
cases of acute poisoning of methanol have been reported, however, obser_
vation of the eyes in workers occupationally exposed to merhanol of lower
concentration and long term contact are rather rare . In this paper
contrast of'the eyes check in 53 workers occupationally exported to me -
thanol and 49 workers not exposed to it were reported .The lowest concentration
of methanol in air of the manufacture workshops of Dawa Chemistry
Factory in Liaoning China is 1 .2rng/m' and the tallest concentration
http://legacy.library.ucsf.edu/tid/clb93d00/pdf
1989 EMS Abstracts 227
Notes