DNA damage induced by micellar-delivered doxorubicin and ultrasound: comet assay study.

To minimize adverse side effects of chemotherapy, we have developed a micellar drug carrier that retains hydrophobic drugs, and then releases the drug by ultrasonic stimulation. This study investigated the DNA damage induced by doxorubicin (DOX) delivered to human leukemia (HL-60) cells from pluronic P-105 micelles with and without the application of ultrasound. The comet assay was used to quantify the amount of DNA damage. No significant DNA damage was observed when the cells were treated with 0.1, 1 and 10 wt% P-105 with or without ultrasound (70 kHz, 1.3 W/cm(2)) for 1 h or for up to 3 h in 10 wt% P-105. However, when cells were incubated with 10 microg/ml free DOX for up to 9 h, DNA damage increased with incubation time (P=0.0011). Exposure of cells to the same concentration of DOX in the presence of 10-wt% P-105 showed no significant DNA damage for up to 9 h of incubation. However, when ultrasound was applied, a rapid and significant increase in DNA damage was observed (P=0.0001). The application of ultrasound causes the release of DOX from micelles or causes the HL-60 cells to take up the micelle encapsulated DOX. Our experiments indicated that the combination of DOX, ultrasound and pluronic P105 causes the largest DNA damage to HL-60 cells. We believe that this technique can be used for controlled drug delivery.

A comparative evaluation of aflatoxin B1 genotoxicity in fish models using the Comet assay.

Aflatoxin B1 (AFB1) is classified as a Group I hepatocarcinogen in humans by the International Agency for Research on Cancer (IARC). The alkaline Comet assay is a simple and rapid method by which DNA damage can be demonstrated as a function of tail moment. The present work is the first to evaluate the genotoxicity of AFB1 in fish using the Comet assay. Two different species of fish were selected as models due to previously established sensitivity to AFB1: rainbow trout (sensitive) and channel catfish (resistant). Fish were i.p. injected with 0.5 mg AFB1/1 ml DMSO/1 kg body weight. The Comet assay was performed after 4 and 24 h on whole blood, liver, and kidney cells of both species. Trout blood and kidney tissue tested displayed significant (p < 0.05) and extensive DNA damage (shown by increased tail moment) after 4 h which then decreased by 24 h. In liver cells, damage progressively increased over time. Conversely, similarly treated catfish showed no elevation in DNA damage over controls at the same doses. These results suggest that the Comet assay is a useful tool for monitoring the genotoxicity of mycotoxins such as AFB1 and for evaluating organ specific effects of these agents in different species.