The bacterium Streptomyces peucetius produces doxorubicin and daunorubicin,and the two widely used anticancer antibiotics.Two open reading frames,drrA and drrB,were proposed to encode for an ABC (ATP-binding cassette) type of permease that carries out export of the antibiotic ABC (ATP binding cassette)-type transporter for the exportation of these two antibiotics.In this paper,the structure,expression and interaction of DrrA and DrrB protein and the research progress of the assembly and multi drug efflux function of DrrAB are briefly reviewed.

Objective To evaluate the endovascular treatment of diffuse aortoiliac occlusive diseases. Methods Thirty-two patients underwent endovascular treatment in which rest pain was found in 84.38%, foot local gangrene in 15.62%. Mean age was 69.7 years (range, 52 years to 81 years) and 71.9% was male. Trans Atlantic Inter-Society Consensus C and D disease was respectively in 40.6% and 59.4% patients. Mean length of vasculopathy was (14.6 ± 1.2) cm (range, 4.5 cm to 19.5 cm) All patients had prohibitive risk for open revascularization. With the approach from femoral artery or brachial artery, combined techniques, such as recanahzation, balloon dilation, stent placement and concomitant common femoral endarterectomy were used. Results Technical success was achieved in twenty-nine patients(90.63%). The complication rate was 3.45%. Clinical status was markedly improved in eight cases (27.59%) and moderately improved in twenty-one cases(72.41%). Mean postoperative ABI was 0.73 ± 0.12, mean preoperative ABI was 0.32 ± 0.09. Significant differences were seen between postoperative ABI and preoperative ABI(P<0.05). Mean time of follow-up was (13.9±6.2) months. At 6 months, primary patency was 81.82% and secondary patency was 89.09%. At 12 months, primary patency was 63.64% and secondary patency was 80.18%. Conclusion Combined multiple endovascular technique is a safe and effective method in the treatment of poor risk diffuse aortoiliac occlusive diseases.