Butovich Igor A
Department of Ophthalmology and Graduate School of Biomedical Sciences, University of Texas Southwestern Medical Center, Dallas, Texas, USA.
Invest Ophthalmol Vis Sci. 2008 Sep;49(9):3779-89. doi: 10.1167/iovs.08-1889. Epub 2008 May 16.
To qualitatively compare the nonpolar lipids present in meibomian gland (MG) secretions (samples T1) with aqueous tears (AT) collected from the lower tear menisci of healthy, non-dry eye volunteers using either glass microcapillaries (samples T2) or Schirmer test strips (samples T3).
Samples T1 to T3 were analyzed with the use of high-pressure liquid chromatography/positive ion mode atmospheric pressure chemical ionization mass spectrometry. Where possible, the unknown lipids were compared with known standards.
Samples T1 had the simplest lipid composition among all the tested specimens. Samples T2 and T3 were similar to each other but were noticeably different from samples T1. In addition to all the compounds detected in samples T1, lower molecular weight wax esters and other compounds were found in samples T2 and T3. No appreciable amounts of fatty acid amides (e.g., oleamide), ceramides, or monoacyl glycerols were routinely detected. The occasionally observed minor signals of oleamide (m/z 282) in samples T3 were attributed to the contamination of the samples with common plasticizers routinely found in plastic ware extractives and organic solvents.
The MG is a prominent source of lipids for the tear film. However, it would have been a mistake to exclude from consideration other likely sources of lipids such as conjunctiva, cornea, and tears produced by the lacrimal glands. These data showed that lipids in AT are more complex than MG secretions, which necessitates more cautious interpretation of the functions of the latter in the tear film.
使用玻璃微毛细管（样本T2）或泪液分泌试验条（样本T3），对睑板腺（MG）分泌物（样本T1）中的非极性脂质与从健康、无干眼症状志愿者下睑泪液弯月面收集的水样泪液（AT）进行定性比较。
使用高压液相色谱/正离子模式常压化学电离质谱对样本T1至T3进行分析。在可能的情况下，将未知脂质与已知标准品进行比较。
样本T1在所有测试样本中脂质组成最为简单。样本T2和T3彼此相似，但与样本T1明显不同。除了在样本T1中检测到的所有化合物外，在样本T2和T3中还发现了较低分子量的蜡酯和其他化合物。常规未检测到大量的脂肪酸酰胺（如油酰胺）、神经酰胺或单酰甘油。在样本T3中偶尔观察到的油酰胺（m/z 282）的微弱信号归因于样本被塑料制品提取物和有机溶剂中常见的增塑剂污染。
睑板腺是泪膜脂质的主要来源。然而，将结膜、角膜和泪腺产生的泪液等其他可能的脂质来源排除在考虑范围之外是错误的。这些数据表明，水样泪液中的脂质比睑板腺分泌物更复杂，这使得在解释后者在泪膜中的功能时需要更加谨慎。
