Apolipoprotein A-I binding to anionic vesicles and lipopolysaccharides: role for lysine residues in antimicrobial properties.

Human apolipoprotein A-I (apoA-I) is a 28kDa protein and a major component of high-density lipoproteins, mediating several essential metabolic functions related to heart disease. In the present study the potential protective role against bacterial pathogens was explored. ApoA-I suppressed bacterial growth of Escherichia coli and Klebsiella pneumoniae. The protein was able to bind lipopolysaccharides and showed a strong preference for bilayer vesicles made of phosphatidylglycerol over phosphatidylcholine. Lysine side chains of apoA-I were acetylated to evaluate the importance of electrostatic forces in the binding interaction with both membrane components. Electrophoresis properties, dot blot analysis, circular dichroism, and fluorescence spectroscopy to probe for changes in protein structure indicated that the acetylated protein displayed a strongly reduced lipopolysaccharide and phosphatidylglycerol binding. A mutant containing only the N-terminal domain of apoA-I also showed a reduced ability to interact with the membrane components, although to a lesser extent. These results indicate the potential for apoA-I to function as an antimicrobial protein and exerts this function through lysine residues.

Estimating the cost of new drug development: is it really 802 million dollars?

This paper replicates the drug development cost estimates of Joseph DiMasi and colleagues ("The Price of Innovation"), using their published cost estimates along with information on success rates and durations from a publicly available data set. For drugs entering human clinical trials for the first time between 1989 and 2002, the paper estimated the cost per new drug to be 868 million dollars. However, our estimates vary from around 500 million dollars to more than 2,000 million dollars, depending on the therapy or the developing firm.