Biopolymers. 2007 Jun 28; [Epub ahead of print]
Borchman D, Foulks GN, Yappert MC, Ho DV.
As a first step to characterize human meibum and tear lipids, infrared spectroscopy was applied to characterize the molecular structure/conformation and packing of hydrocarbon chains. Temperature-induced phase transitions were fit to a sigmoid equation and were experimentally reproducible and were similar for multiple samples collected from the same person. No hysteresis was observed. Hydration of polar tear lipids increased their phase transition cooperativity, enthalpy and entropy. Hydrophobic interactions in meibum lipid (ML) were stronger than in tear-fluid lipids (TL), as reflected by the higher entropy and enthalpy of the gel to liquid crystalline phase transition of ML.The results of this study provide further evidence of the differences in the composition and structure of ML and TL. The conformational changes observed in the hydrocarbon chains of ML with temperature suggest that the observed therapeutic increased delivery of ML with eye lid heating could be related to the increased disorder in the packing of the hydrocarbon tails. This work also highlights the power of infrared spectroscopy to characterize molecular structure/conformation, and packing of human tear lipids and provides a basis to be applied next to study tear film lipid composition-structure-function relationships and lipid-protein interactions in relation to age, sex and dry eye symptoms. (c) 2007 Wiley Periodicals, Inc. Biopolymers, 2007.
MOST interesting. I have been so pleased to see an escalation of interest in heat treatment for MGD at last. Sounds like we are on our way to learning more about the actual mechanics and what form(s) are most likely to be helpful to various types of conditions? Hurray. May we see much more investigational work along these lines.
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