A. Maura

Cytotoxicity, DNA fragmentation and sister-chromatid exchange in Chinese hamster ovary cells exposed to the lipid peroxidation product 4-hydroxynonenal and homologous aldehydes.

The cytotoxic and genotoxic activities of 4-hydroxypentenal (HPE), 4-hydroxyhexenal (HHE), 4-hydroxyoctenal (HOE), 4-hydroxynonenal (HNE) and 4-hydroxyundecenal (HUE) were investigated in Chinese hamster ovary (CHO) cells. All five 4-hydroxyalkenals reduced plating efficiency in a concentration (ranging from 7 to 170 microM) lower than that producing a parallel reduction of trypan blue-excluding cells, but with both methods the increase in molarity needed to obtain a lethal effect was constantly rather small. With all five 4-hydroxyalkenals a significant amount of DNA fragmentation, as revealed either by the alkaline elution assay or by alkaline denaturation followed by chromatographic partition of single- and double-stranded DNA, was detected only after cell exposure to a cytotoxic concentration. HPE, HHE and HOE induced a clear-cut increase of sister-chromatid exchange (SCE) frequency, while that displayed by cells treated with HNE and HUE was minimal, even if dose-dependent and statistically significant. Since 4-hydroxyalkenals have been shown to originate from biomembrane lipids peroxidation, these findings should be taken into consideration in the assessment of the genotoxic role of lipoperoxidation in humans.

Negative evidence in vivo of DNA-damaging, mutagenic and chromosomal effects of eugenol

The DNA-damaging, mutagenic and chromosomal effects of eugenol were assayed by the DNA alkaline elution technique, the granuloma pouch assay and the bone marrow micronucleus test in rats. With all the techniques used, eugenol did not show any genotoxic activity.

Formation of DNA‐damaging nitroso compounds by interaction of drugs with nitrite. A preliminary screening for detecting potentially hazardous drugs

Fifty-seven theoretically nitrosatable widely used drugs that are commonly administered orally have been screened to determine the formation of nitroso compounds by drug-nitrite interaction and to evaluate the genotoxicity of their nitrosation products against Chinese hamster ovary (CHO) cells, measured as DNA-damaging potency by the alkaline elution technique. The drug (0.1 mmol) was reacted with NaNO2 (0.4 mmol) at pH 3-3.5 for 1 h. Nitroso compounds were present in varying yield in the nitrosation mixture of 47 drugs. Twenty-two drugs formed direct-acting nitroso compounds capable of producing DNA fragmentation, i.e., a statistically significant (p less than 0.01) increase in the elution rate of CHO cell DNA. On a molar basis, their DNA-damaging potency varied over a 570-fold range, with 12 exhibiting greater potency than that of N-nitroso-N-methylurea.

DNA damage in stomach, kidney, liver and lung of rats treated with atrazine

The genotoxic activity of atrazine, a widely used triazine herbicide, was assayed by the DNA alkaline elution technique in rats given orally a single high dose or repeated daily doses. DNA breaks (and/or alkali-labile lesions) were detected in cell suspensions obtained from stomach, kidney and liver, but not in those from lung.

Physico-chemical model for DNA alkaline elution: New experimental evidence and differential role of DNA length, chain flexibility and superpacking

For a better understanding of data provided by DNA alkaline elution technique, a new analytical model has been developed which takes into consideration both the physicochemical properties of in situ DNA strand (length and flexibility/superpacking) and the geometric and hydrodynamic configuration of the elution apparatus (flow and filter conditions). Simulation by this model of experimental data previously obtained before and after carcinogens administration, has shown that for constant flow and filter conditions elution profiles are dependent, not only from DNA molecular weight, but also from a parameter critically related to modifications in chain flexibility/superpacking. This has been confirmed by several independent observations, including the time-dependent changes in non-denaturing lysing solution monitored by hydroxylapatite and alkaline elution techniques.

DNA Alkaline Elution: Physical Basis of the Elution Process and Validation of this Method as a Screening Procedure to Identify Chemical Carcinogens

The alkaline elution technique, developed by Kohn and coworkers (Kohn and Ewig, 1973; Kohn et al., 1976; Kohn, 1979), provides a sensitive measurement of DNA single-strand size distribution in mammalian cells and represents an advanced alternative to the technique of alkaline sucrose gradient sedimentation. Alkaline elution of DNA from cell lysates allows size measurement of DNA single strands longer than the sizes that can be measured by sedimentation in alkaline sucrose gradients. The elution technique requires relatively simple and not expensive apparatuses, and is less time-consuming in comparison with the latter. Moreover, it gives more repeatable results and is more suitable to assess DNA damage from various tissues following in vivo exposure to DNA interacting agents. In the last few years, this technique has been widely applied by different groups of researchers to the study of various DNA lesions induced by several physical or chemical agents (ranging from carcinogens to antineoplastic agents), and a large series of results have been collected. The aims of this review are: to discuss the physical basis that governs DNA elution, to summarize the possible application of this method, to revise the use of alkaline elution and its reliability in the assessment of DNA fragmentation in various organs of mice and rats following in vivo exposure to chemical agents, and to evaluate critically its role as a screening procedure for carcinogenic compounds.

Evaluation of DNA damage induced by norfloxacin in liver and kidney of adult rats and in fetal tissues after transplacental exposure

Norfloxacin, a recently developed antimicrobial fluoroquinolone, was investigated for DNA-damaging activity in rat liver and kidney. After oral administration of single doses ranging from 1 to 8 mmole/kg, DNA fragmentation was absent in liver and kidney both 2 and 6 h after treatment. However, when administered to pregnant rats, the highest doses produced a detectable amount of DNA damage in fetal tissues. This damage appears to be an aspecific consequence of maternal and fetal toxicity rather than a specific genotoxic effect.

DNA damage and repair by alkaline elution in N-diazo-acetylglycine amide-treated cells

Abstract In mouse fibroblast-like cells treated in vitro with N-diazoacetylglycine amide (DGA), the DNA damage and repair were evaluated by means of the alkaline elution technique. The results show that DGA induces a dose-dependent damage of DNA which is repaired only slowly. The DGA-induced damage increases for the first 2 h allowed for repair, regresses up to that displayed at the end of exposure period after 4–24 h of repair, and is evidently lower after a 48-h repair period. These results agree with the demonstrated mutagenic and carcinogenic activity of DGA.

Induction of sperm abnormalities in mice by norfloxacin

Norfloxacin was tested in the mouse sperm morphology test. Data obtained suggest that norfloxacin may have 2 different effects on sperm development: a stimulating effect on spermatogenesis and a possible mutagenic effect that results in an increase in sperm abnormalities. The first effect might be caused by a hormonal action. A dose-response relationship was not observed in sperm morphology changes. Consequently norfloxacin cannot with certainty be judged a positive inducer of abnormal sperm, but further studies are essential to clarify the obtained results.

Dna damage induced by nitrosated ranitidine in cultured mammalian cells

Ranitidine, a new H-2 receptor antagonist more potent than cimetidine in inhibiting gastric secretion, reacted under acid conditions with a twofold molar amount of nitrite (a nitrite/ranitidine ratio about 1000 times that likely to occur in gastric juice of treated humans) yielding a nitroso derivative capable of inducing a dose-dependent DNA fragmentation in cultured Chinese hamster ovary cells.