Environmental and Molecular Mutagenesis - Legacy Tobacco ...

14 1989 EMS Abstracts
Notes
http://legacy.library.ucsf.edu/tid/clb93d00/pdf
IN UTERO AND MALE MEDIATED-EFFECTS OF 1,2-DIBROlIO-3-CHLOROPROPANE IN RATS . W.W. Au,
D . Walker and M .S . Legator . Department of Preventive Medicine and Community Health,
University of Texas Medical Branch, Galveston, Texas 77550, USA .
In utero and male-mediated effects after oral exposure to Sprague Dawley rate to 1,
2-dibromo-3-chloropropane (DBCP) were investigated . DBCP was administered to timedpregnant
females on days 11 and 15 of gestation at single doses of 1, 10, 50 and 150
mg/kg . Calls were harvested g hours after treatment . Chromatid breaks and exchange
figures were significantly elevated in pooled whole-embryo cell suspensions and in
pooled fetal liver cells from females treated on day 15 . A doae related response was
observed, even at the lowest concentration . In the dominant lethal test, DBCP was
administered in doses of 1, 10 and 50 mg/kg for 5 consecutive days, with 5 males in
each group . The males were each mated to 2 untreated females 4 and 5 weeks later . In
the combined 4 and S week results, a dose-responsive effect was seen in the dominant
lethal index (number of live fetuses in treated compared to nontreated females) . In
addition to the dominant lethal effect using the same protocol but allowing the pups
to go to term, a post natal effect was found . A significant number of new born rats
died within 24 hours after birth . This increase in post natal death was dose dependent,
with a effect found at the lowest concentration used, 1 mg/kg/day for 5 days .
AFLATOXIN ADDUCTS AS A MEASURE OF EXPOSURE .
Autrup, H ., Fibiger Institute, Danish Cancer Society, DK-2100 Copenhagen
Denmark .
Aflatoxin 81, a potent human liver carcinogen, is metabolized by cytochrome
P-450 oxidases to several metabolites, including the electrophilic
8,9-epoxide . This metabolite will react with in nucleic acids and
proteins . The major DNA adduct is formed in the reaction between the
N-7 position of guanine and the epoxide . This adduct is unstable, and
would either ringopen to the more stable AFB-FAPY adduct or depurinate .
The latter product is excreted in urine . Human exposure to aflatoxin
has been determined by measuring the amount of AFS-FAPY in human liver
samples from China, and by detecting the depurinated product in urine
collected in Kenya . The sensitivity of both assays is 5 adducts per
1oE7 nucleotides . Aflatoxin 8,9-epoxide also reacts with serum albumin,
and the major adduct is formed with lysine, This adduct is detected in
blood collected in China, and a positive association between exposure
level and binding to serum albumin has been established . Three different
methological approached with equal sensitivity and specificity have
been developed to assess the biological active dose of aflatoxin Bl in
humans .
jLl SITU DETECTION OF DNA DAMAGE IN SINGLE CELLS OR TISSUE SECTIONS BY QUANTITATIVE
IMMUNOFLUORESCENCE MICROSCOPY
RA Baan, L Roza, GP van der Schans, MWM van Loon and CJM van der Wulp
TNO Medical Biological Laboratory, P0 Box 45, 2280 M, Rijswijk, The Netherlands
The interaction of reactive chemical species with DNA - leading to the formation of DNA
adducts - is considered to be an important step in mutation and cancer initiation . To
study the correlation between the presence of DNA adducts and mutation induction, methods
are required to detect and quantify DNA damage . Correlations between DNA lesions and
biological effects may be used to develop rlsk-asses,ment procedures . Molecular dosimetry
of DNA damage can be used to estimate the extent of genotoxic exposure . .
The present work is aimed at the application of issiunoohemical methods to assess gsnotoxic
damage in a limited number of cells or at the single-cell level . This approach involves
the development of antibodies specific for a particular DNA lesion, and the use of such
antibodies for detection of DNA damage in fixed calls or tissue sections by laser-scan
immunofluorescence microscopy (IFM) . The fluorescence is quantified by analog-digital
conversion and data-processing in a Microdutch 100 computer with the software package
TCL-image . The IFN technique has been or will be used for various purposes :
the study of induction and removal of thymine dimers, with dimsr-specific antibodies,
in UV-irradiated cultured human fibroblasts or skin ∎ections .
analysis of benzo(a)pyrene(BP)-DNA adducts in human white blood cells with antibodies
specific for the BP-daoxyguanosine adduct, to monitor exposure to polycyclic aromatics .
- detection of DNA damage induced in germ cells by ionising radiation, with antibodies
specific for single-stranded regions in DNA, to study repair processes in such cells .
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