A biological evaluation of DNA damage detected by comet assay in healthy populations residing in areas that differ in lung cancer incidence.

The comet assay was performed to evaluate the effect of environmental exposure between human populations residing in two areas that differ in lung cancer incidence, Saraphi (n = 91) and Chom Thong (n = 94). Three parameters, the tail length, tail intensity, and tail moment, were used to detect DNA damage in peripheral blood and stimulated lymphocytes with and without the DNA repair inhibitor, aphidicolin. Internal standards, cryopreserved isolated lymphocytes, and isolated lymphocytes irradiated with 2 Gy gamma rays, were used to correct the interexperimental variability. Results revealed a significant difference between two populations only when the tail length was used to measure DNA damage. The evaluation of various potential confounding factors, such as gender, pesticide exposure, smoking, alcohol drinking, and fermented tea leaf or betel nut chewing, indicated no significant influence in DNA damage. In conclusion, significant difference in DNA damage, detected only by tail length between the two populations residing in the areas with different incidence of lung cancer, may reflect a nonhazardous level of exposure to toxic substances.

Dna quantities and qualities from various stages of some trematodes using optical and HAT-RAPD methods.

The aim of this experiment was to minimize DNA quantity and quality for detection by optical (spectrophotometer at 260 nm and 280 nm) and HAT-RAPD methods. Total DNA from different stages, adult, metacercaria and eggs of 6 trematode species were isolated for analysis. In this experiment, the adult trematodes were classified into 3 groups by size: small, Haplorchis taichui and Stellantchasmus falcatus; medium, Opisthorchis viverrini and Ganeo tigrinus; and large, Paramphistomum epiclitum and Fischoederius elongatus. The adult minimal DNA quantities and qualities of all specimen samples detected by optical method were 97.22,72.28, 3,167.00, 1,490.62, 21,382.66, and 27,321.77 ng; eggs were 3.92, 3.57, 3.72, 6.23, 17.53, and 14.01 ng, respectively; and metacercarial stages 50.70 and 40.98 ng in H. taichui and S. falcatus. In addition, the HAT-RAPD technique was chosen to amplify the minimal DNA qualities and quantities of all trematode specimens. Total DNA was 1-1 x 10(-12) ng; DNA templates in each dilution were used for amplification by primer OPA-09. DNA concentrations ranging between 1 x 10(-8) and 1 x 10(-11) ng were amplified with high polymorphism. Our experiment concluded that only a single specimen of each egg, metacercaria, or adult stage could be amplified with distinct bands.

A comparative biomonitoring study of populations residing in regions with low and high risk of lung cancer using the chromosome aberration and the micronucleus tests.

Chromosome aberration (CA) and micronucleus (MN) tests were performed in peripheral blood lymphocytes from people residing in two districts of Chiang Mai, Thailand, a high-risk area, Saraphi (n=107), where the lung cancer incidence is three-fold higher than in a low-risk area, Chom Thong (n=118). The percentage of cells with CAs was significantly lower in the Saraphi population than in the Chom Thong population (0.47+/-0.91 versus 1.04+/-1.18, P=0.0001) as was the percentage of CAs (0.49+/-0.91 versus 1.08+/-1.21, P<0.0001) and the mitotic indices (1.25+/-0.44 versus 1.33+/-0.33, P=0.025). The frequency of MN in binucleated (BN) cells, however, was significantly higher in the Saraphi population (12.01+/-3.57 versus 9.99+/-3.11, P<0.0001) as was the percentage of BN cells with MN (1.14+/-0.31 versus 0.93+/-0.23, P<0.0001). There was no difference in the nuclear division indices (1.49+/-0.07 versus 1.47+/-0.11, P=0.1759) between the two populations. With regard to the effect of confounding factors, it was found that cigarette smoking influenced both CA and MN frequencies, and that the chewing of fermented tea leaves or betel nuts affected CA and sex affected MN frequencies. An increasing of CA and MN frequencies were seen in smokers and chewers over non-smokers and non-chewers, with CA frequencies being higher in Chom Thong smokers and chewers and MN frequency being higher in Saraphi smokers. However, pesticide exposure and alcohol consumption had no impact on CA and MN frequencies. Due to the conflicting results obtained in the two tests, we cannot make a clear statement regarding the potential effects of the environmental exposures in the two study populations.

Some factors affecting Stellantchasmus falcatus metacercaria in laboratory.

Killing factors, various temperatures and solutions were studied in the laboratory on Stellantchasmus falcatus metacercaria in half-beaked fish (Dermogenus pusillus). Killing criteria followed the Movability Index from 1.000 within 24 hours. The metacercariae were collected from Chiang Mai moat. They were incubated in 0.85 % NaCl at -20 degrees C, room temperature, 4 degrees, 37 degrees, and 65 degrees C. The in vitro investigation showed that at -20 degrees C and 65 degrees C, the worms were killed within 18 and 2 hours, respectively, while other temperatures produced no effect. The solutions investigated were NaCl (10, 20, 30, and 40%), lemon juice (25, 50, 75, and 100%), acetic acid (5, 10, 20, and 30%), vinegar (1, 3, and 5%) and water as a control. The worms were killed in NaCl at 20, 30, and 40% within 12, 6, and 2 hours, respectively. Acetic acid at 5% and 10% killed the metacercaria within 12 and 6 hours while at 20% and 30%, within 2 hours. The killing effect of 3% vinegar was found within 18 hours and of 5% vinegar within 12 hours. Lemon juice showed no killing effect.