The Di‐ and triesters of the lipids of steer and human meibomian glands

Nicolaides, Nicholas C.; Santos, Evelyn Cristina da Silva

doi:10.1007/bf02534237

Cited by 62 publications

(83 citation statements)

References 21 publications

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“…These results confi rmed independent observations from a number of research laboratories on the presence of large amounts of CEs and WEs in human meibum (18)(19)(20)(21)(22)(23). However, we could not concur on the reported fi ndings on oleamide ( 24 ), Cer, and other typical polar lipids ( 25,26 ).…”

Section: Discussionsupporting

confidence: 72%

“…This was a clear sign of the presence of at least two isobaric compounds in the mixture. We hypothesized that these novel compounds might be related to the relatively poorly characterized families of di-and triesters of various kinds postulated by Nicolaides and Santos ( 19 ), specifi cally, the (O-acyl)--hydroxy FA (OAHFA) peroxyacetic acid as described in Materials and Methods. Then, both treated and untreated samples were analyzed by HPLC-MS side by side.…”

Section: Epoxides Of Wax Estersmentioning

confidence: 99%

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Human tear film and meibum. Very long chain wax esters and (O-acyl)-omega-hydroxy fatty acids of meibum

Butovich

Wojtowicz

Molai

2009

Journal of Lipid Research

159

158

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by various laboratories during the last few decades ( 1-8 ).In TF, meibum is believed to form its outermost layer, which retards evaporation of water from the bulk of TF and from the ocular surface beneath it ( 7 ). Yet another function of meibum is to form a hydrophobic barrier along the margins of the eyelids to contain TF at, and prevent it from leaking out of, the designated ocular surface area ( 2 ). These protective functions imply a very hydrophobic nature of meibum. Indeed, the major meibum components were identifi ed as various wax esters (WEs) and cholesteryl esters (CEs) with long-chain and very longchain FA ( 9-11 ). The information on acylglycerol content of meibum is more limited as no defi nite structural information on the putative meibomian acylglycerols is currently available ( 12, 13 ). Interestingly, lipidomic analyses of human meibum demonstrated that its composition is distinctively different from that of sebum. For example, free cholesterol, squalene, ceramides (Cers), and typical phospholipids were shown to be minor components of meibum ( 9-11, 14, 15 ), although they dominated in the skin ( 16,17 ).Meibum has been analyzed using various experimental techniques, discussion of which goes beyond the scope of this article. Recently, we published preliminary results on the lipid composition of human meibum and tears ( 9-11, 15 ). The major method employed in these studies was normal phase high performance liquid chromatography in combination with atmospheric pressure chemical ionization mass spectrometry (NP HPLC-MS). The main advantage of the NP HPLC is its ability to separate different classes of lipids. For example, mono-, di-, and triacylglycerols (MAGs, DAGs, and TAGs, respectively) elute as three distinctively different groups of HPLC peaks and so do other groups of lipids (free FAs and their amides and Meibum is a lipid-rich secretion that is produced by Meibomian glands located at the ocular lid margins of both upper and lower eyelids of various mammals and humans. Meibum is an intrinsic part of the human tear fi lm (TF), the main role of which is to protect the ocular surface from dehydration. Among other proposed functions of TF are antimicrobial, lubricatory, and nutritional ones. For general information on meibum and TF, the reader is advised to read earlier comprehensive reviews published

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Section: Discussionsupporting

confidence: 72%

Section: Epoxides Of Wax Estersmentioning

confidence: 99%

Human tear film and meibum. Very long chain wax esters and (O-acyl)-omega-hydroxy fatty acids of meibum

Butovich

Wojtowicz

Molai

2009

Journal of Lipid Research

159

158

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“…For example, it has been reported that there are some 30 000 different lipid molecular species just in the human meibum (tear gland) [19]! Cell membranes are composed, in part, of at least hundreds, perhaps thousands, of different lipids.…”

Section: Role Of Cholesterol In Lipid Raftsmentioning

confidence: 99%

The location and behavior of α‐tocopherol in membranes

Atkinson

Harroun

Wassall

et al. 2010

Molecular Nutrition Food Res

173

128

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Vitamin E (a-tocopherol) has long been recognized as the major antioxidant in biological membranes, and yet many structurally related questions persist of how the vitamin functions. For example, the very low levels of a-tocopherol reported for whole cell extracts question how this molecule can successfully protect the comparatively enormous quantities of PUFAcontaining phospholipids found in membranes that are highly susceptible to oxidative attack. The contemporary realization that membranes laterally segregate into regions of distinct lipid composition (domains), we propose, provides the answer. We hypothesize a-tocopherol partitions into domains that are enriched in polyunsaturated phospholipids, amplifying the concentration of the vitamin in the place where it is most needed. These highly disordered domains depleted in cholesterol are analogous, but organizationally antithetical, to the wellstudied lipid rafts. We review here the ideas that led to our hypothesis. Experimental evidence in support of the formation of PUFA-rich domains in model membranes is presented, focusing upon docosahexaenoic acid that is the most unsaturated fatty acid commonly found. Physical methodologies are then described to elucidate the nature of the interaction of a-tocopherol with PUFA and to establish that the vitamin and PUFA-containing phospholipids co-localize in non-raft domains.

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“…Investigation of the vanishingly small quantity of lipid in human tear film presents a unique challenge for study, and a range of analytical approaches have been applied to quantify the lipids in both tears and meibum 8,9 . A comprehensive overview of the molecular lipid composition of human tears has recently been realized through application of contemporary mass-spectrometric analytical tools [10][11][12] .…”

Section: Introductionmentioning

confidence: 99%

Intersubject and Interday Variability in Human Tear and Meibum Lipidomes: A Pilot Study

et al. 2016

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Mitchell, T. W. (2016). Intersubject and interday variability in human tear and meibum lipidomes: a pilot study. The Ocular Surface, 14 (1), 43-48. Intersubject and interday variability in human tear and meibum lipidomes: a pilot study Abstract Purpose Our aim was to quantitate day-to-day changes in the tear and meibum lipid profile of individual subjects in a pilot study of healthy humans. Methods Matched tear and meibum samples were obtained from four subjects on three consecutive days. Quantitative lipid profiles of human basal tears and meibum were compared using multivariate analysis by principal components. Results Substantial differences in the lipid profile between subjects were observed, while lipid profiles were steady across the three consecutive days of sampling. Multivariate principal component analysis demonstrated that lysophosphatidylcholine was the largest variant lipid class between subjects in tears, while wax esters comprised the most variation between subjects in meibum secretions. Conclusion Interday variability is shown to be much smaller than interpatient variability, suggesting that tears and meibum subjects both have unique profiles in humans. Disciplines Medicine and Health Sciences Publication DetailsBrown, S. H. J., Kunnen, C. M. E., Papas, E. B., Lazon de la Jara, P., Willcox, M. D. P., Blanksby, S. 2 ABSTRACT Purpose: Our aim was to quantitate day-to-day changes in the tear and meibum lipid profile of individual subjects in a pilot study of healthy humans.Methods: Matched tear and meibum samples were obtained from four subjects on three consecutive days. Quantitative lipid profiles of human basal tears and meibum were compared using multivariate analysis by principal components.Results: Substantial differences in the lipid profile between subjects were observed, while lipid profiles were steady across the three consecutive days of sampling.Multivariate principal component analysis demonstrated that lysophosphatidylcholine was the largest variant lipid class between subjects in tears, while wax ester contributed the most to variation between subjects in meibum secretions.Conclusion: Inter-day variability is shown to be much smaller that inter-patient variability, suggesting that both tears and meibum subjects have unique profiles in individuals.

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The Di‐ and triesters of the lipids of steer and human meibomian glands

Cited by 62 publications

References 21 publications

Human tear film and meibum. Very long chain wax esters and (O-acyl)-omega-hydroxy fatty acids of meibum

Human tear film and meibum. Very long chain wax esters and (O-acyl)-omega-hydroxy fatty acids of meibum

The location and behavior of α‐tocopherol in membranes

Intersubject and Interday Variability in Human Tear and Meibum Lipidomes: A Pilot Study

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