Detection of Cytogenetic Effects in Peripheral Lymphocytes of Students Exposed to Formaldehyde with Cytokinesis-Blocked Micronucleus Assay

Cytokinesis-blocked micronucleus assay was applied as a biological dosimeter to detect abnormalities in human peripheral lymphocytes of thirteen students exposed to formaldehyde (FA) during a 12-week (10 h per week) anatomy class. Breathing-zone air samples colleeted during dissection procedures showed a mean concentration of 2. 37 ppm (3. 17mg/m3 ). Ten students from the same school but without FA exposure served as controls. Chromosome aberrations (CA) and sister chromatid exchanges (SCE) were detected in both groups. The micronuclei (MN) rate (6. 38 ± 2. 50‰ ) and CA rate (5. 92 ±2. 40‰ ) in the FA-exposed group showed a significant increase (P< 0. 01 ) when compared with those of the controls (3. 15 ±1. 46‰and 3. 40 ± 1. 57 % respectively). A correlation between MN and CA in individuals was observed. SCE in the exmpd group were also increased (P< 0. 05), but not so greatly as MN or CA. The results indicated that FA might damage the chromosomes of human lymphocytes.

Evaluation of Protective Effects of Bioactive Phytochemicals Against Methotrexate in Salmonella typhimurium TA1535/pSK1002 Coupled with Micronucleus Assay

We evaluated the antimutagenic effects kinds of bioactive phytochemicals and of 10 some phytochemical combinations against methotrexate （MTX）-induced genotoxicity by the umu test in Salmonella typhimurium TA1535/rpSK1002 combined with a micronucleus assay. We observed that allicin, proanthocyanidins, polyphenols, eleutherosides, and isoflavones had higher antimutagenic activities than the other five types of bioactive phytochemicals. At the highest dose tested, MTX-induced genotoxicity was inhibited by 25%-75%. Kunming mice treated by MTX along with bioactive phytochemical combinations showed significant reduction in micronucleus induction and sperm abnormality rate （P〈0.01）. These results indicate that bioactive phytochemical combinations can be potentially used as new cytoprotectors.

NASOPHARYNGEAL CARCINOMA RADIOSENSITIVITY PREDICTION BY CYTOKINESIS－BLOCK MICRONUCLEUS ASSAY

Cytokinesis-block micronucleus method is used to evaluate the radiosensitivity of a nasopharyngeal carcinoma cell line (CNE-1) and biopsies obtained from 31 patients with nasopharyngeal carcinoma. The number of micronuclei increases with theradiation dose. A good correlation was found between the radiosensitivity determined by the micro-nucleus assay and that measured by the colony-forming assay in CNE-1 cell line (r=-0.998). Moreover, the results of micronucleus assay for tumor cells from biopsies of patients with primary carcinoma look promising for the prediction of tumor radiosensitivity. These results are encouraging but fleed to be confirmed with a larger number of patients with a longer follow-up.

Evaluation of drinking water treatment combined filter backwash water recycling technology based on comet and micronucleus assay

Based on the fact that recycling of combined filter backwash water（CFBW）directly to drinking water treatment plants（WTP）is considered to be a feasible method to enhance pollutant removal efficiency,we were motivated to evaluate the genotoxicity of water samples from two pilot-scale drinking water treatment systems,one with recycling of combined backwash water,the other one with a conventional process.An integrated approach of the comet and micronucleus（MN）assays was used with zebrafish（Danio rerio）to investigate the water genotoxicity in this study.The total organic carbon（TOC）,dissolved organic carbon（DOC）,and trihalomethane formation potential（THMFP）,of the recycling process were lower than that of the conventional process.All the results showed that there was no statistically significant difference（P〉0.05）between the conventional and recycling processes,and indicated that the genotoxicity of water samples from the recycling process did not accumulate in 15 day continuous recycling trial.It was worth noting that there was correlation between the concentrations of TOC,DOC,UV（254）,and THMFPs in water and the DNA damage score,with corresponding R^2 values of 0.68,0.63,0.28,and 0.64.Nevertheless,both DNA strand breaks and MN frequency of all water samples after disinfection were higher than that of water samples from the two treatment units,which meant that the disinfection by-products（DBPs）formed by disinfection could increase the DNA damage.Both the comet and MN tests suggest that the recycling process did not increase the genotoxicity risk,compared to the traditional process.

Response of Lymphocytes to Radiation in Untreated Breast Cancer Patients as Detected with Three Different Genetic Assays

Objective To detect the response of lymphocytes to radiation in untreated breast cancer patients with three different genetic assays. Methods Blood samples were collected from 25 untreated patients and 25 controls. Each blood sample was divided into two parts： one was irradiated by 3-Gy X-ray （irradiated sample）, the other was not irradiated （non-irradiated sample）. The radiosensitivity of lymphocytes was assessed by comet assay, cytokinesis-block micronucleus （CBMN） assay and 6-TG-resistant cells scored （TG） assay. Results The baseline values of micronucleated cell frequency （MCF） and micronucleus frequency （MNF） in the patients were significantly higher than those in the controls （P〈0.01）, and 3-Gy X-ray induced genetic damage to lymphocytes in the patients increased significantly as compared with that in the controls as detected with the three genetic assays （P〈0.01）. The proportion of radiosensitive cases in the patient group was 48% for the mean tail length （MTL）, 40% for the mean tall moment （MTM）, 40% for MCF, 44% for MNF, and 48% for mutation frequencies of the hprt gene （Mfs-hprt）, respectively, whereas the proportion of radiosensitive cases in the control group was only 8% for all the parameters. Conclusion The difference in the lymphocyte radiosensitivity between the breast cancer patients and the controls is significant. Moreover, there are wide individual variations in lymphocyte radiosensitivity of patients with breast cancer. In some cases, the radiosensitivity of the same patient may be different as detected with the different assays. It is suggested that multiple assays should be used to assess the radiosensitivity of patients with breast cancer before therapy.

Effect of pollution on DNA damage and essential fatty acid profile in Cirrhinus mrigala from River Chenab

The objective of this study was to evaluate the effect of anthropogenic pollution on DNA damage and the fatty acid profile of the bottom dweller fish （Cirrhinus mr^gala）, collected from the River Chenab, in order to assess the effect of the toxicants on the quality of the fish meat. The levels ofCd, Hg, Cu, Mn, Zn, Pb, Cr and Sn and of phenols from this river were significantly higher than the permissible limits set by the USEPA. Comet assays showed DNA damage in Cirrhinus mr^gala collected from three different sampling sites in the polluted area of the river. Significant differences were observed for DNA damage through comet assay in fish collected from polluted compared to control sites. No significant differences were observed for DNA damage between farmed and fish collected from upstream. The micronucleus assay showed similar trends. Fish from the highly polluted sites showed less number of fatty acids and more saturated fatty acids in their meat compared to fish from less polluted areas. Several fatty acids were missing in fish with higher levels of DNA in comet tail and micronucleus induction. Long-chain polyunsaturated fatty acids, eicosapentaenoic acid （20：5n-3） was found missing in the fish from polluted environment while it was found in considerable amount in farmed fish 7.8±0.4%. Docosahexaenoic acid （22：6n-3） also showed significant differences as 0.1±0.0 and 7.0±0.1% respectively, in wild polluted and fanned fishes.

Genotoxicity of Synthetic Food Colorants

A study was conducted to evaluate the genotoxicity, if any, of the permitted synthetic food colorants used in India. Eight synthetic food colorants namely Erythrosine （E 127）, Tartrazine （E 102）, Ponceau 4R （E 124）, Sunset Yellow FCF （E 110）, Brilliant Blue FCF （E133）, Fast Green FCF （E143）, Carmoisine （E122） and Indigo Carmine （E132） and their combination are used in sweets namely Ladu, Jilebi and Halwa in Calicut and suburban areas of Kerala, in India. The genotoxicity of the colorants alone and in combinations at different concentrations were evaluated by Cytokinesis Block Micronucleus （CBMN） Assay. It was observed that all the above colorants and their combinations could cause genotoxicity to human lymphocytes even at the permissible concentration of 100 ppm as per PFA （Prevention of Food Adulteration） Act of India. The toxicity varied from dye to dye and was proportional to their concentration. Combination of colors showed more toxicity than the individual components. Toxicity could be reduced drastically by reducing the concentration of the dyes at least 50% below the permissible limit. Permitted synthetic food colorants even at the permissible limit should be used with caution. This study demonstrated the need for redefining the permissible limit of the food colorants based on Admissible Daily Intake （ADI） as being practiced in developed countries.

Phyllanthus emblica Linn.fruit extract potentiates the anticancer efficacy of mitomycin C and cisplatin and reduces their genotoxicity to normal cells in vitro

Objective： Fruit of Phyllanthus emblica Linn. （PE） is widely consumed as a functional food and used as a folk medicine due to its remarkable nutritional and pharmacological effects. Mitomycin C （MMC） and cisplatin （cDDP） are the most widely used forms of chemotherapeutic drug, but their clinical use is limited by their genotoxicity to normal cells. We aimed to determine whether PE has potential to reduce the genotoxicity, while improving the anticancer effect, of MMC and cDDP. Methods： Cell proliferation was evaluated using the trypan blue exclusion assay and colony-forming assay. Genomic instability （GIN） was measured using the cytokinesis-block micronucieus assay. Results： Co-treatment （72 h） with PE at 20-320 μg/ml significantly enhanced the efficacy of MMC （0.05 μg/ml） and cDDP （1 μg/ml） against Colo205 colorectal cancer cells （P〈0.05）, and at 80-320 μg/ml significantly decreased MMC- and cDDP-induced GIN and multinucleation in normal colonic NCM460 cells （P〈0.05）. PE significantly decreased the mitotic index （P〈0.01）, blocked mitotic progression （P〈0.05）, and promoted apoptosis （P〈0.01） in MMC- and cDDP-treated NCM460 cells, suggesting that PE-mediated inhibition of mitosis and induction of apoptosis may limit the division and survival of highly damaged cells. Also, PE was found to inhibit the clonal expansion of MMC- and cDDP-treated NCM460 cells （P〈0.05） and decrease the heterogeneity of the surviving clones. Conclusions： PE potentiates the anticancer efficacy of MMC and cDDP, while preventing their genotoxicity and inhibiting clonal expansions of unstable genomes in normal cells. These data suggest that PE has the potential to reduce the risk of secondary cancers induced by chemotherapeutics.