Delivery of Methoprene-Tolerant dsRNA to Improve RNAi Efficiency by Modified Liposomes for Pest Control.

The application of RNA interference (RNAi) technology for pest control is environmentally friendly and accurate. However, the efficiency of RNAi is often inconsistent and unreliable, and finding a suitable carrier element is considered critical to success in overcoming biotic and abiotic barriers to reach the target site. The fall armyworm, Spodoptera frugiperda (FAW), which is one of most important global agricultural pests, has recently spread rapidly to other parts of the world. In this study, a method to improve the stability and RNAi efficiency of the dsRNA carrier complex was reported. Methoprene-tolerant gene (Met) was selected as a target, a gene which is critical to the growth and development of FAW. Biomaterials nanoliposomes (LNPs) were modified with polyethylenimine (PEI) to deliver the dsRNA of Met. The synthesized Met3@PEI@LNPs reached a size of 385 nm and were found to load dsRNA effectively. Through stability and protection assays, it was found that LNPs provided reliable protection. In addition, the release curve also demonstrated that LNPs were able to prevent premature release under alkaline condition of the insect midgut but accelerate the release after entering the acidic environment of the target cells. The cell transfection efficiency of the prepared LNPs reached 96.4%. Toxicity tests showed that the use of LNPs could significantly improve the interference efficiency, with 91.7% interference efficiency achieved when the concentration of dsRNA in LNPs was only 25% of that of the control. Successful interference of Met demonstrated it could significantly shorten the larval period and make the larvae pupate earlier, thus achieving the purpose of control. In this study, we have demonstrated the use of nanotechnology to provide a novel RNAi delivery method for pest control.

Comparative analgesia, cardiovascular and renal effects of celecoxib, rofecoxib and acetaminophen (paracetamol).

Comparisons are made between the specific COX-2 inhibitors, celecoxib and rofecoxib, and acetaminophen. The specific COX-2 inhibitors are a significant advance in therapy because their anti-inflammatory, analgesic and antipyretic activities are associated with a high degree of gastrointestinal safety. Acetaminophen is often not considered to be a potent inhibitor of COX-2 but it is a potent inhibitor of prostaglandin synthesis in intact cells after stimulation by cytokines. Its weak activity on the pathway of prostanoid synthesis involving COX-1 is shown by its weak anti-platelet activity and good gastrointestinal safety. The specific COX-2 inhibitors and acetaminophen are analgesic after dental surgery, orthopedic surgery and in osteoarthritis although acetaminophen appears to be a slightly weaker agent. The apparent analgesic activity of both the COX-2 inhibitors and acetaminophen may, in part, be due to their anti-inflammatory properties. Both groups of drugs also decrease the urinary excretion of prostacyclin metabolites consistent with inhibition of the systemic and renal activity of the COX-2 system. During repeated dosage with the specific COX-2 inhibitors, the 24 hour urinary excretion of sodium is only inhibited for the first day of treatment while the excretion of sodium is still decreased over the first 3 hours after the individual doses. Therapeutic doses of the COX-2 inhibitors and overdoses of acetaminophen have been associated with the development of occasional cases of acute renal failure. Acetaminophen also may decrease the excretion of sodium and the reason for its greater renal safety at therapeutic doses is unclear. Myocardial infarction has also been attributed to the specific COX-2 inhibitors from meta-analysis of large scale clinical trials and examination of reports of adverse drug reactions although this is still a topic of considerable discussion. No such associations have been made with acetaminophen, possibly because it is a weak inhibitor of COX-1 in platelets.