13C 和 1H NMR 酯区域共振分配及人婴儿和儿童睑板腺分泌物的组成。

13C and 1H NMR ester region resonance assignments and the composition of human infant and child meibum.

机构信息

Department of Ophthalmology and Visual Sciences, University of Louisville, Kentucky Lions Eye Center, 301 E. Muhammad Ali Blvd., Louisville, KY 40202, USA.

出版信息

Exp Eye Res. 2013 Jul;112:151-9. doi: 10.1016/j.exer.2013.04.017. Epub 2013 May 1.

Abstract

Recent NMR studies suggest that unsaturation may contribute to tear film instability in adults and loss of cholesteryl esters and squalene could reduce tear film stability in adults with meibomian gland dysfunction. The proton resonances were tentatively assigned in those studies. In this current investigation, meibum from seven infants and children, one adult and a pool of adult meibum have been analyzed using an NMR spectrometer with greater sensitivity and spectral resolution. The goals of this work are to confirm/correct the previous assignments and to determine possible age-related changes in composition. The initial resonance assignments were confirmed using heteronuclear single quantum correlation spectroscopy. Because there were no significant interferences in the spectral region corresponding to the resonances for cholesteryl and wax esters, the areas of these resonances were used to calculate their molar ratios. We calculated a wax ester:cholesteryl ester molar ratio of 1:0.57 ± 0.05 for all our meibum samples and there were no age-related differences. At lower film thicknesses, the rate of evaporation measured in vitro was lower for wax esters mixed with a long chain cholesteryl ester compared to wax esters alone. However, the film thicknesses tested were non-physiological. Longer chain cholesteryl esters increase the interactions between hydrocarbon chains. Hydrocarbon chains were more saturated in meibum from infants and children compared to adults. Unsaturation may contribute to tear film instability in adults. Loss of cholesteryl ester and squalene could destabilize tear film in adults with meibomian gland dysfunction.

摘要

最近的 NMR 研究表明,不饱和可能导致成年人的泪膜不稳定,而胆固醇酯和角鲨烯的丧失可能会降低患有睑板腺功能障碍的成年人的泪膜稳定性。在这些研究中,质子共振被暂定分配。在本当前研究中,使用具有更高灵敏度和光谱分辨率的 NMR 光谱仪分析了来自七个婴儿和儿童、一个成年人和一组成年人的睑脂。这项工作的目的是确认/纠正以前的分配,并确定组成可能与年龄相关的变化。使用异核单量子相关光谱法确认了初始共振分配。由于在对应于胆固醇和蜡酯的共振的光谱区域中没有明显的干扰,因此使用这些共振的面积来计算它们的摩尔比。我们计算了所有我们的睑脂样本的蜡酯:胆固醇酯摩尔比为 1:0.57 ± 0.05,并且没有与年龄相关的差异。在较低的膜厚度下,在体外测量的蒸发速率对于与长链胆固醇酯混合的蜡酯比单独的蜡酯低。然而,所测试的膜厚度是非生理的。较长链的胆固醇酯增加了烃链之间的相互作用。与成年人相比,婴儿和儿童的睑脂中的烃链更饱和。不饱和可能导致成年人的泪膜不稳定。胆固醇酯和角鲨烯的丧失可能会使患有睑板腺功能障碍的成年人的泪膜不稳定。

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