Fast and reliable screening of mutations in human tumors: use of multiple fluorescence-based long linker arm nucleotides assay (mf-LLA).

Human tumor samples were screened for point mutations by adapting a mobility-shift assay to automated DNA sizing. This screen identifies the type of point mutation and relative amount of mutated DNA sequences present in a sample. Test samples having known hypoxanthine-guanine phosphoribosyl transferase (hprt)/exon-3 sequence mutations were characterized by: (i) PCR amplification, (ii) fluorescent dye-primer extension with 36-atom linker derived deoxycytosine or deoxyuridine triphosphate and the remaining three natural nucleotides and (iii) sizing of the resulting fluorescently labeled modified strands, using an automated DNA sequencer. Routinely, a range of sizes is observed among the sequence variants of a single DNA target sequence. This is because nucleotide analogs are incorporated into DNA strands in a sequence-dependent manner, resulting in composition-dependent electrophoretic mobility. Thus, point mutations are identified as shifts in mobility between the fluorescently labeled modified strands of the control and test samples. The twenty different hprt/exon-3 single-base substitution mutations tested were easily identified, even at fourfold dilution with control DNA.

Monitoring of exposure to acrylonitrile by determination of N-(2-cyanoethyl)valine at the N-terminal position of haemoglobin.

A selected ion monitoring gas chromatography-mass spectrometry (GC-MS) procedure was developed to determine the interaction product formed by acrylonitrile (ACN) with the N-terminal amino group in haemoglobin. The product, N-(2-cyanoethyl)valine (CEV), was analysed following its release from the protein by a modified Edman degradation procedure. Quantitation was achieved using N-(2-cyanoethyl)-[2H8]Val-Leu-Ser as internal standard. The limit of detection of the assay was 1 pmol CEV/g globin. A close to linear dose-response relationship was found for adduct formation in rats treated with ACN by gavage. On the basis of a linear extrapolation, a dose of 1 mg/kg body wt yielded 248 pmol CEV/g globin. Two groups of workers who were exposed to ACN contained 1984 +/- SD 2066 (n = 9) and 2276 +/- SD 1338 (n = 7) pmol CEV/g globin respectively. These values were highly significantly greater (P < 0.01 following a one-way analysis of variance with a logarithmic transformation of the data) than those in a group of control workers in the same factory (31.1 +/- SD 18.5 pmol CEV/g globin, n = 11). The concentrations of N-terminal CEV in globin samples from 13 smoking and 10 non-smoking mothers and from their newborns were determined. Adduct levels in the smokers averaged 217 +/- 85.1 pmol CEV/g globin, significantly higher than the levels in non-smokers, which were undetectable. Individual values in the mothers were very highly correlated with the levels in their babies (which averaged 99.5 +/- 53.8 pmol CEV/g globin), which demonstrates that transplacental transfer of ACN occurs. Significant correlations were also found between the number of cigarettes smoked per day by the mother and the CEV levels in both the mothers' and newborns' globin. There was, however, no correlation between the CEV levels and those of the ethylene oxide adduct N-(2-hydroxyethyl)valine in samples from either the mothers or babies.

Evaluation of some biomonitoring markers in occupationally exposed populations to acrylonitrile.

In the present work we studied acrylonitrile (AN) occupationally exposed populations and respective control individuals working in a Portuguese plant producing acrylic textile fibers. Three subgroups of individuals were considered: controls (C), workers of the continuous polymerization (CP) area, and workers of equipment maintenance (MM). Besides aiming to contribute to a better understanding of the hazardous exposure of man to AN, the study aimed to help validate and optimize the use of a combination of methods applied to human populations exposed to genotoxic compounds. Three main compartments related to the dose or effect of the hazardous compound were evaluated using various assessment methods: 1) internal dose (genotoxicity in urine, indicators of oxidative stress, induction of cytochromes P450); 2) biological effective dose (hemoglobin adducts); and 3) early biological effects (chromosomal aberrations, sister chromatid exchanges). Although concern with exposure to AN has long been the subject of numerous studies, they have been carried out essentially in animals and using in vitro systems. The significant differences (P < 0.01) found in the chromosomal aberrations of MM are in agreement with the highly significant levels of hemoglobin adducts described in another study performed in the same population. Hemoglobin adducts were also sensitive in detecting a hazardous exposure in the case of CP. The results obtained for the lipid peroxidation indicator used seem to confirm the AN capability of inducing lipid peroxidation in vivo. From the results available it seems that chromosomal aberrations as well as hemoglobin adducts are accurate and sensitive biomonitoring markers for AN exposure.