Lung surfactant (LS) is vital to our survival, allowing the surface of our lungs to rapidly contract and expand with each breath, and substantially decreasing the work of breathing. Yet the mechanisms involved remain ill understood. The absence in functioning lung surfactant in the lungs of premature infants results in respiratory distress syndrome (RDS). Both synthetic and natural lung surfactant replacements have been designed to treat RDS and have substantially reduced the mortality rate in premature infants. However, these replacements are costly, show poor efficiency or carry a high risk of infection or rejection by the patient’s immune system. Also, the treatment of adult respiratory distress syndrome, which is often associated with lung injury, remains problematic. Obtaining an understanding of the complex mechanisms involved is key to the design of drugs used to treat RDS and other respiratory diseases. The phase transitions of dipalmitoylphosphatidylcholine (DPPC, the primary lipid component in natural lung surfactant) are thought to play an important role in the mechanism by which lung surfactant is able to reduce and regulate the surface tension in the lungs. The primary focus of our research is to apply coarse grained and atomistic molecular dynamics simulations to the study of the phase transitions of lipid monolayers containing DPPC, interactions of DPPC with other relevant LS components, and structural transitions occuring in the monolayer at near zero surface tension. These simulations act to elucidate the mechanisms involved in physiological surface tension reduction and are complementary to the vast amount experimental data available on the subject, providing information on a length and time scale that is difficult or impossible to obtain experimentally and a novel approach to this complex problem.
 
Publications
[1] S.L. Duncan and R.G. Larson, Biophys. J. 94:2965-2986, 2008 "Comparing experimental and simulated pressure-area isotherms of DPPC."
[2] S.L. Weitz and J.J. Potoff, Fluid Phase Equilib. 234:144-150, 2005 "The effect of quadrupole moment on the phase behavior of binary mixtures containing ethene."
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