Cationic liposomes,as non-viral vectors,are widely used in gene therapy and gene silencing.Although numerous cationic liposomes have various structures,they can all improve the per-formance of gene delivery.As gene therapy is increasingly studied,it may be foreseen that new cationic lipoplexes will be explored.In this review,we aim to discuss four constituent domains of cationic lipids(headgroup,hydrophobic domain,linker and helper lipids)in gene delivery.This article attempts to demonstrate that various lipid structures show different transfection efficiency and cytotoxicity by sum-marizing the similarities and differences between the four parts of cationic lipids.Furthermore,their major influencing factors are covered.Finally,three clinical cases of ionizable lipids are described to reveal their characteristics and differences from cationic lipids.This paper is intended to provide a conceptual framework for the design of cationic liposomes and for the selection of cationic lipids.

OBJECTIVETo observe the effects of electroacupuncture (EA) pretreatment at different times for heart arrest induced by bupivacaine poisoning in rats.

METHODSWith a randomized, blind, control study, 24 SD rats were divided into a control group, a EA for 60 min (EA 60) group and a EA for 30 min (EA 30) group, 8 cases in each one. Rats in the EA 60 group and EA 30 groups were treated with EA at bilateral "Neiguan" (PC 6), "Zusanli" (ST 36) and "Fenglong" (ST 40) for 60 min and 30 min respectively. While no treatment was given in the control group. Then rats were monitored by leadⅡelectrocardiograph; catheters were inserted into the femoral vein to open the vein access and into the carotis to monitor the arterial pressure. Three hours after EA, 10 mg/kg bupivacaine was injected through femoral vein. The mean arterial pressure (MAP) and heart rate (HR) were automatically recorded by PowerLab system. The time points when QRS widened by 20 percent and cardiac arrest and the survival rates were observed.

RESULTSAfter the injection of bupivacaine, five rats in the EA 60 group caught cardiac arrest,while all the rats in the other two groups caught it. The survival rates were not statistically significant among the three groups (>0.05). The time of QRS widening by 20 percent in the EA 60 group was (87.4±14.8) s,which was longer than (63.6±14.2) s in the EA 30 group and (51.2±12.4) s in the control group (both<0.05). From injection of bupivacaine to cardiac arrest, the time of (375.3±23.7) s in the EA 60 group and that of (328.3±47.7)s in the EA 30 group were more than (235.5±91.5) s in the control group (both<0.05). After the injection, MAP and HR in the EA 60 group were higher than those in the EA 30 group and control group at most time points (all<0.05).

CONCLUSIONSEA pretreatment apparently decreases the vulnerability of bupivacaine-induced heart arrest, with better protective effect of 60 min pretreatment than that of 30 min.