Impact of nicotine-induced green tobacco sickness on DNA damage and the relation with symptoms and alterations of redox status in tobacco farmers.

During the harvest period, tobacco workers are exposed to nicotine and it is known that absorption of the alkaloid via the leaves causes green tobacco sickness (GST). We investigated if GST and its symptoms are associated with DNA damage and alterations of the redox status. DNA damage was measured in lymphocytes of tobacco workers and controls (n = 40/group) in single cell gel electrophoresis assays. Exposure to nicotine was determined by plasma cotinine measurements, alterations of the redox status by quantification of the total antioxidant capacity (TEAC) and of thiobarbituric acid reactive substances (TBARS). The symptoms of GTS included nausea, abdominal cramps, headache, vomiting and dizziness, and 50% of the workers had more than one symptom. Cotinine levels were enhanced in the workers (111 ng/mL); furthermore, the extent of DNA damage was ca. 3-fold higher than in the controls. This effect was more pronounced in participants with GST compared to healthy nicotine exposed workers and increased in individuals with specific symptoms (range 22-36%). TBARS levels did not differ between workers and unexposed controls, while TEAC values were even increased (by 14.3%). Contact with nicotine present in tobacco leaves causes GTS and leads to damage of the DNA; this effect is more pronounced in workers with GTS symptoms and is associated with alterations of the redox status. Damage of the genetic material which was found in the workers may lead to adverse long-term effects that are caused by genomic instability such as cancer and accelerated ageing.

Micronuclei and other nuclear anomalies in exfoliated buccal mucosa cells of Mexican women with breast cancer.

PURPOSE: Breast cancer (BC) is the most frequently diagnosed form of cancer and the leading cause of cancer-related deaths among females in the world. RESULTS of several studies showed that the genome of primary cancer patients (naive for any treatment) is unstable. The purpose of the present study was to evaluate the genomic instability in BC patients by means of buccal cells micronucleus (MN) cytome assay Methods: The frequencies of nuclear anomalies including MN, binucleates (BN), broken eggs (BE), condensed chromatin (CC), karyorrhexis (KR) and karyolysis (KL) were evaluated in exfoliated buccal mucosa cells of Mexican women with primary BC and healthy women. Buccal cells were collected from 21 BC patients (9 with stage I and 12 with stage II) and from 20 healthy females used as control group. RESULTS: The results of the evaluation of cells showed that the frequencies of MN, BN, BE, KR and KL were significantly increased in the pooled group of BC patients compared with the control group. However, no one parameter of buccal MN-cytome assay in patients with stage I BC was significant compared with controls and BC patients with stage II. CONCLUSION: Application of the buccal MN-cytome assay for the study of genomic instability in primary BC patients showed that both genotoxic and cytotoxic effects can be evaluated in such patients.

Induction of nuclear anomalies in exfoliated buccal cells of coca chewers: results of a field study.

The leaves of coca (Erythroxylum coca var. coca), a South American shrub which contains cocaine, other alkaloids and phenolics are widely used by indigenous populations of the Andes. It is currently not known if coca consumption causes genotoxic effects in humans. This information is important to predict potential long-term toxic effects such as cancer induction. Therefore, the buccal cytome assay was used to analyze oral cells from 45 uni- and bilateral chewers and 23 controls living in the Altiplano of the Peruvian Andes. In total, 123,471 cells were evaluated from chewers and 57,916 from controls. Information concerning the consumption levels and habits and also use of lime were collected with questionnaires. Chewing of the leaves did not induce nuclear anomalies reflecting genetic damage such as micronuclei (MNi) and nuclear buds; in the highest exposure group (but not in the overall group) even a significant decrease in the frequencies of cells with MNi (by 64 %) was observed. However, we found significantly elevated levels of other nuclear anomalies (karyorrhexis and karyolysis) which reflect cytotoxic effects in the coca users. The frequencies of these anomalies increased with the daily consumption and when lime was used to improve the release of the alkaloids. In contrast to other chewing habits (betel, tobacco and khat), consumption of coca leaves does not induce genetic instability in cells from the oral cavity and our findings indicate that no adverse health effects take place in chewers which are associated with DNA damage. However, the significant increase in certain anomalies shows that acute toxic effects are caused by coca consumption.

Evaluation of the genotoxic and anti-genotoxic activities of silybin in human hepatoma cells (HepG2).

Silybin (SB), a constituent of the medicinal plant Silybum marianum, is reported to be a potent hepatoprotective agent, but little is currently known regarding its genotoxicity, mutagenicity and potential chemopreventive properties. In this study, we evaluated the ability of SB to induce DNA migration and micronuclei (MN) formation in human hepatoma cells (HepG2). Also, possible preventive effects of SB on MN formation induced by three different mutagens, bleomycin (BLEO), benzo[a]pyrene (B[a]P) and aflatoxin B(1) (AFB(1)), were studied. To clarify the possible mechanism of SB antimutagenicity, three treatment protocols were applied: pretreatment, in which SB was added before the application of the mutagens; simultaneous treatment, in which SB was added during treatment and post-treatment, in which SB was added after the application of the mutagens. At concentrations up to 100 microM, SB was non-genotoxic, while at a concentration of 200 microM, SB induced DNA migration, generated oxidized DNA bases, reduced cell viability, decreased the replicative index of the cells and induced oxidative stress. It is noteworthy that SB was able to reduce the genotoxic effect induced by B[a]P, BLEO and AFB(1) in pretreatment and simultaneous treatments but had no significant effect on DNA damage induction in post-treatment. Taken together, our findings indicate that SB presents anti-genotoxic activity in vitro, which suggests potential use as a chemopreventive agent.

Evaluation of the genotoxicity of treated urban sludge in the Tradescantia micronucleus assay.

The sludge produced in sewage treatment plants can contain toxic substances. Among these, the genotoxic substances are of great concern. The present paper aimed at evaluating the genotoxicity of treated sludge samples collected at four different sewage treatment plants (STP) located in the State of São Paulo, Brazil using the Trad-MN assay. Another objective of the study was to compare the responses of the Clone #4430 with the Tradescantia pallida. Sludge samples mixed with reference soil in concentrations of 10, 25 and 50% (v/v) were tested in experiments with 3 months exposure in the field. Negative and positive controls (arsenic trioxide) were also tested with both plants. In Clone #4430 two sludge samples induced genotoxicity while in T. pallida three were positive, although no clear dose-response were observed for both plants. Results with the negative and positive controls suggest that T. pallida presented similar results when compared to the Clone #4430. The protocol using plants chronically exposed to sludge mixed with soil seems to be a promising tool to assess the genotoxicity of sludge although time consuming.