Mutational fingerprint induced by the antineoplastic drug chloroethyl-cyclohexyl-nitrosourea in mammalian cells.

Using the pZ189 shuttle vector approach, we determined two chloroethyl-cyclohexyl-nitrosourea (CCNU)-induced mutation spectra (3 and 6 mM) in African green monkey kidney cells (CV1). One hundred and twenty-one independent clones (101 CCNU induced, 45 at 3 mM and 56 at 6 mM; 20 spontaneous) showing functional inactivation of the supF gene were analyzed. One hundred and five plasmids (91 CCNU induced, 41 at 3 mM and 50 at 6 mM; 14 spontaneous), showing no large deletion/rearrangements, were sequenced.

Mixed pleomorphic-osteoclast-like tumor of the pancreas. Light microscopical, immunohistochemical, and molecular biological studies.

The morphological, immunohistochemical, and molecular biological features of a case of giant cell tumor of the pancreas are described. This neoplasm showed mononuclear and multinucleated tumor giant cells as well as numerous osteoclast-like cells with multiple foci of osteoid-osseous metaplasia. The pleomorphic and osteoclastic giant cells displayed extensive homologies in their immunohistochemical profiles.

p53 expression in normal versus transformed mammalian cells.

To answer the question whether the level of p53 expression also reflects the status of a cell, with reference to transformation and genome stability, we have examined, by immunocytochemistry, the presence of p53 protein in a number of cell types including human diploid cells, Chinese hamster embryonal cells at different passages and gene amplified and/or transformed Chinese hamster cell lines. Primary human fibroblasts at early passage (LEO) and an established, non transformed, Chinese hamster cell line at early passage (CHEF/18) did not show any detectable p53 expression, either nuclear or cytoplasmic. All transformed human (Raji) and Chinese hamster cell lines (CHO, V79, V79/B7) showed a nuclear expression of p53, although at different intensities.

Induction of kinetochore-containing micronuclei by exogenous O6-methylguanine requires conversion of the methylated base to a nucleotide.

It has been reported that exogenous alkylated purines, such as O6-methylguanine (O6meG), induce aneuploidy in mammalian cells. It is shown here that the aneugenic effect of O6meG, evidenced by its ability to induce micronuclei in rodent cells, is dependent on its conversion to O6-methyl-guanosine-5'-monophosphate (O6me-5'-GMP) by hypoxanthine-guanine phosphoribosyl transferase (HPRT). This conclusion, in contrast with previous in vitro data showing that O6meG does not seem to be a substrate for HPRT, was based on the following observations: 1) O6meG did not induce micronuclei in HPRT-deficient Chinese hamster cells, but did induce micronuclei in HPRT-proficient cells, and in mouse cells partially or totally deficient in adenine phosphoribosyl transferase; 2) O6meG was not metabolized in HPRT-deficient cells, while in wild-type cells a number of metabolites were detected by high performance liquid chromatography (HPLC) analysis of cold acid extracts, one of them coeluting with O6me-5'-GMP used as a marker; 3) when de novo synthesis of purine nucleotides was inhibited by aminopterin, O6meG sustained the growth of HPRT-proficient, but not of HPRT-deficient, cells; and 4) when HPRT-deficient cells were treated with liposomes charged with O6me-5'-GMP, induction of micronuclei was shown.

Mutation spectrum of 4-nitroquinoline 1-oxide-damaged single-stranded shuttle vector DNA transfected into monkey cells.

4-Nitroquinoline 1-oxide (4NQO) is a potent mutagen and carcinogen which induces two main guanine adducts at positions C8 and N2. We recently determined the mutation spectrum induced by the ultimate metabolite of 4NQO, acetoxy-4-aminoquinolone 1-oxide in the M13lacZ'/E. coli lacZ delta M15 alpha-complementation assay.

Pleural mesothelioma and asbestos exposure among Italian oil refinery workers.

Objectives: The association between asbestos exposure and risk of mesothelioma was studied among workers from two oil refineries located in the northern Italian cities of Genoa and La Spezia, given that previous cohort analyses revealed two clusters of mesotheliomas and that international cohort studies have so far not reported an excess of this neoplasm among oil refinery workers.

Methods: Men (N = 2300) who had been employed between 1914 and 1988 in two oil refineries located in northern Italy were studied. The follow-up covered the mortality of 639 white-collar and 1661 blue-collar from 1950 to 1991.

Defective splicing induced by 4NQO in the hamster hprt gene.

The molecular analysis of mutations affecting mRNA processing may contribute to a better understanding of the splicing mechanism through the identification of genomic sequences necessary for the recognition of splice sites. In this paper we report the sequence analysis of 14 splice mutants induced by 4-nitroquinoline 1-oxide (4NQO) at the hamster hypoxanthine-guanine-phosphoribosyltransferase (hprt) locus. We show that mutations at the 3' acceptor splice site or at the first or fifth base of the 5' donor splice site are responsible for exon skipping.

Analysis of 4-nitroquinoline-1-oxide induced mutations at the hprt locus in mammalian cells: possible involvement of preferential DNA repair.

Mutation spectra induced by 4-nitroquinoline 1-oxide (4NQO) at the hprt locus for both normal (AA8) and 4NQO-sensitive (UV5) Chinese hamster ovary cells were determined to investigate the effect of DNA repair on the nature of induced mutations. The UV5 cell line is three times more sensitive to 4NQO than the AA8 parental cell line. In UV5 cells, the dGuo-N2-AQO adduct, which is considered to be the most toxic and mutagenic adduct in Escherichia coli, is poorly repaired.

Genotoxic effects of the carbamate insecticide methomyl. I. In vitro studies with pure compound and the technical formulation "Lannate 25".

The carbamate insecticide methomyl and the methomyl-containing technical formulation "Lannate 25" were tested on whole blood human lymphocyte cultures. Both products induced dose-dependent increases in chromosome aberrations and micronuclei. Lannate 25 induced DNA damage as measured by the alkaline elution assay and hydroxylation of guanine at the C8 position.

The 4-nitroquinoline 1-oxide mutational spectrum in single stranded DNA is characterized by guanine to pyrimidine transversions.

4-Nitroquinoline-1-oxide is a potent mutagen and carcinogen which induces two main guanine adducts at positions C8 and N2. In ds or ss damaged DNA the ratio C8/N2 adducts is 1:2 and 8-10:1, respectively. In bacteria and yeast 4NQO has been shown to be a base substitution mutagen acting at G residues inducing mainly G to A transitions.

The analysis of 10 potential spindle poisons for their ability to induce CREST-positive micronuclei in human diploid fibroblasts.

Ten compounds selected for use within a coordinated Commission of the European Communities programme on aneuploidy induction (cadmium chloride, chloral hydrate, colchicine, diazepam, econazole, hydroquinone, pyrimethamine, thiabendazole, thimerosal and vinblastine) were tested for their ability to induce CREST-positive micronuclei in cultured human diploid fibroblasts. Significant increases in CREST-positive micronuclei were produced by cadmium chloride, chloral hydrate, colchicine, diazepam and vinblastine. Thiabendazole produced a significant increase in the ratio of CREST-positive to CREST-negative micronuclei and was also classified as positive.

Time resolved fluoroimmunoassay of 7-methyl-2'-deoxyguanosine imidazole (ring open).

A solid-phase competitive time-resolved fluoroimmunoassay for 7-methyl-2'-deoxyguanosine imidazole (ring open) is described, based on highly specific hemocyanin carrier rabbit antibodies, modified with europium chelates. Eu3+ photoluminescence was detected in a novel micellar solution. The assay was validated both by comparing it with an ELISA and by analysing DNA samples, alkylated either 'in vitro' or 'in vivo' by dimethyl sulfate.

Time-resolved fluoroimmunoassay of aflatoxins.

Preparation of purified and Eu-labeled antibodies specific for aflatoxins is described. Their use is illustrated by a solid-phase competitive time-resolved fluoroimmunoassay, results of which were correlated with those of an enzyme-linked immunosorbent assay based on use of the unmodified antibody to aflatoxin. This procedure is discussed as a quick, sensitive, and reliable immunoassay for use in mycotoxin screening in foodstuffs and body fluids.