Eftimov Petar, Ewurum Anthony, Ankem Akhila, Borchman Douglas, Georgiev Georgi As
Department of Cytology, Histology and Embryology, Faculty of Biology, St. Kliment Ohridski University of Sofia, Bulgaria.
Department of Chemistry, University of Louisville, Louisville, KY, USA.
Chem Phys Lipids. 2022 Jan;242:105163. doi: 10.1016/j.chemphyslip.2021.105163. Epub 2021 Dec 2.
In a recent study (Ewurum et al., 2021), wax (WE) and sterol esters (CE) from human meibum secretions (MGS) were separated and reconstituted with controlled WE/CE ratios (0%, 20%, 30%, 40%, 50%, 75% and 100% CE weight fractions). It was found that the alterations in the CE content of WE/CE mixtures modified the hydrocarbon chain conformation and packing of the mixture. A major question that emerges is whether the spectroscopic packing parameters determined for bulk meibum translate to a change in the performance of meibomian layers at the air/water interface, as it is the surface film functionality that is crucial for the performance of MGS at the ocular surface. The study of human meibum films with Langmuir surface balance was performed to access the surface properties at blink-like deformations of the film area. Surface pressure (π)-area (A) isocycles and stress relaxations were used to assess the layer's reorganization during area cycling and dilatational elasticity, respectively. The morphology of the films was monitored by Brewster angle microscopy. It was found that the increased order and chain melting temperature of the bulk samples correlated with a raise in the maximum surface pressure attained at minimal surface area and in the transient dilatational modulus of the meibomian layers. Such correlations may allow for development of an improved understanding between the bulk and surface properties of human meibum and of other natural and synthetic tear lipid films.
在最近的一项研究（Ewurum等人，2021年）中，从人睑板腺分泌物（MGS）中分离出蜡（WE）和甾醇酯（CE），并以可控的WE/CE比例（0%、20%、30%、40%、50%、75%和100% CE重量分数）进行重构。研究发现，WE/CE混合物中CE含量的变化改变了混合物的烃链构象和堆积。由此出现的一个主要问题是，为整体睑脂测定的光谱堆积参数是否会转化为睑板层在空气/水界面处性能的变化，因为表面膜功能对于MGS在眼表的性能至关重要。利用朗缪尔表面天平对人睑脂膜进行研究，以获取膜面积在类似眨眼变形时的表面性质。表面压力（π）-面积（A）等温线和应力松弛分别用于评估面积循环过程中层的重组和扩张弹性。通过布鲁斯特角显微镜监测膜的形态学。研究发现，整体样品的有序度增加和链熔化温度升高与在最小表面积时达到的最大表面压力以及睑板层的瞬态扩张模量升高相关。这种相关性可能有助于加深对人睑脂以及其他天然和合成泪液脂质膜的整体性质与表面性质之间关系的确切理解。
