RESUMEN
<p><b>BACKGROUND</b>To establish an ADM resistant Lewis lung cancer cell line and to investigate its biological characteristics.</p><p><b>METHODS</b>The multidrug-resistant cell line was gradually induced by ADM from Lewis lung cancer cell line (L3-8), its growth characteristics and cancinogenicity were observed. The fluorescent density of ADM and Rh-B in the cells were analyzed by IPP image analysis system. The ADM concentration in cells was assayed with fluorescent meter. The IC50 was evaluated by MTT assay and the drug resistant index was counted.</p><p><b>RESULTS</b>The drug resistant Lewis lung cancer cell line, L3-8/ADM, which can grow in the medium containing 0.4mg/l ADM was acquired after 14 months selective culture. Its tumor generatic rate was 10/10. When the L3-8/ADM was cultured in 0.15mg/l ADM and general 1640 medium, the doubling time was 22.0h and 21.8h separately. After culturing in 4mg/l ADM and Rh-B medium, the fluorescent density ratio of L3-8/ADM and L3-8 were 2.82:1 and 2.65:1 separately. The ADM concentration of L3-8/ADM was only 64.7% of its parental, but there was no significant difference in their ADM release rate. Except for ADM, L3-8/ADM was resistant to DNR, VCR, MIT and CDDP in different degrees.</p><p><b>CONCLUSIONS</b>L3-8/ADM cell is a typical MDR cell line. The cell membrane obstruction of drug infiltration might be the cause of drug resistance. This study will provide a basis for the establishment of lung cancer MDR animal model.</p>
RESUMEN
<p><b>OBJECTIVE</b>To develop a simple and reliable method for intensifying the hybridization signals of gene chips.</p><p><b>METHODS</b>The authors added EDTA and another FAM-labeled probe to the normal PCR products, denatured the mixture by heat, and then let the mixture hybridize with the fastened probes on the chip.</p><p><b>RESULTS</b>With the use of EDTA and another FAM-labeled probe, the hybridization signals increased by 6 times or greater.</p><p><b>CONCLUSION</b>Adding EDTA and another probe to the normal PCR products is a simple and efficient method to intensify the hybridization signal of chips.</p>