PURPOSE: To determine the polar lipid composition of @entity1 meibomian gland secretions and their relationship to the preocular tear film. METHODS: Meibomian secretions were collected from normals and @entity1 with chronic @entity14985 . These lipids (meibum) were first separated by thin layer chromatography. Polar lipids were then separated utilizing high-pressure liquid chromatography with ultraviolet detection. Individual peaks were identified by comparison with standards. Collected sample peaks were subjected to differential transmethylation with @entity1042 - @entity1042 and the resulting @entity15006 were analyzed by gas chromatography-mass spectroscopy. RESULTS: Three phospholipids were identified as @entity2434 , @entity3633 and @entity4291 ; other unidentified phospholipids were also present. Also present in secretions were the sphingolipids @entity9932 and cerebrosides. @entity1718 present were 12-18 @entity505 chain length. All @entity1718 were normal (not branched) saturated @entity1718 except in sphingolipids, where @entity41660 were also present. Unsaturated normal @entity1718 were present only in meibum from @entity1 with @entity14938 . CONCLUSIONS: The composition of the polar lipids in meibomian gland secretions is more complex than previously thought. On the other hand, the type and @entity505 chain length of the polar lipid @entity1718 appears strictly controlled. The relationship of these findings to the preocular tear film should be considered in terms of overall functionality. The polar lipid layer most likely is only one to three molecules thick and serves as a surfactant between aqueous tears and the thicker nonpolar lipid layer.

Polar lipids in XXXX meibomian gland secretions.

@entity1 :: ('9606', 'Species') :: ['human', 'patients'] @entity1042 :: ('MESH:D000432', 'Chemical') :: ['methanol', 'sodium methoxide'] @entity14985 :: ('MESH:D001762', 'Disease') :: ['blepharitis'] @entity2434 :: ('MESH:D010713', 'Chemical') :: ['phosphatidylcholine'] @entity41660 :: ('CHEBI:24654', 'Chemical') :: ['hydroxy fatty acids'] @entity3633 :: ('MESH:C483858', 'Chemical') :: ['phosphatidylethanolamine'] @entity9932 :: ('MESH:D002518', 'Chemical') :: ['ceramides'] @entity505 :: ('MESH:D002244', 'Chemical') :: ['carbon'] @entity1718 :: ('MESH:D005227', 'Chemical') :: ['Fatty acids', 'fatty acids'] @entity15006 :: ('CHEBI:4986', 'Chemical') :: ['fatty acid methyl esters'] @entity4291 :: ('CHEBI:17636', 'Chemical') :: ['sphingomyelin'] @entity14938 :: ('MESH:D017043', 'Disease') :: ['meibomianitis']
@entity1 :: (9606,Species) :: ['human']
