Diffusivity and structural polymorphism in some model stratum corneum lipid systems.
Diffusivity and structural polymorphism in some model stratum corneum lipid systems.
复制标题
一些模型角质层脂质系统的扩散性和结构多态性。
DOI：
10.1016/0005-2736(93)90088-h
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发表时间：
1993
期刊：
影响因子：
--
通讯作者：
G. Lee
中科院分区：
文献类型：
--
作者：
R. Lieckfeldt;J. Villalaín;J. Gomez;G. Lee
以胆固醇、六种脂肪酸和神经酰胺为原料，在水中制备了模型角质层脂的混合物。测定了组成对这些混合物的多态以及模型药物D LIP在其中的扩散系数的影响。前者由X射线衍射法和傅里叶变换红外光谱仪获得，后者由扩散释放模型得到。形成了Lβ结构，其组成与完整的人腹部角质层细胞外脂类物质的组成相似。D LIP在20-40%w/w范围内与水含量无关，双层呈现一维膨胀，没有侧向膨胀。虽然神经酰胺的去除并没有导致D LIP的显著改变，但结晶胆固醇现在出现了。因此，神经酰胺对于在完整SC的脂肪部分中存在的大比例胆固醇的脂肪酸双层内的增溶是必要的。他们也负责大约观察到的Lα-H II的热转变。68°。在完整SC中存在的浓度下，胆固醇对D LIP的影响也很小，但对于抑制脂肪酸中H II相的形成和确保Lβ结构是必要的。所有具有Lβ结构的脂类混合物都呈现出大约扩散障碍。比无结构、各向同性的脂类混合物大1个数量级。胆固醇/脂肪酸摩尔比小于约8：92时形成的H II结构比Lβ结构具有更强的渗透性。所有结果表明，Lβ相的存在基本上保证了模型脂混合物中的扩散屏障。虽然神经酰胺和胆固醇对D LIP的大小没有内在的影响，但它们的存在是存在33°的Lβ相的必要条件，该相不具有结晶胆固醇和H II特征。
Mixtures of model stratum corneum lipids were prepared in water from cholesterol, six fatty acids and ceramides. The influence of composition on the polymorphism of these mixtures and also on the diffusivity of a model drug within them, D lip, was determined. The former was obtained from X-ray diffraction and Fourier transform infrared spectrometry, and the latter from a diffusional release model. An Lβ structure was formed for the composition approximating that of the extracellular lipids in intact human abdominal stratum corneum. D lip was independent of water content in the range 20–40% w/w, with the bilayers showing one dimensional swelling without lateral expansion. Although removal of the ceramides did not result in a significant alteration in D lip, crystalline cholesterol now appeared. The ceramides were, therefore, necessary for solubilization within the fatty acid bilayers of the large proportion of cholesterol present in the lipid fraction of intact SC. They were also responsible for a thermal L α-H II transition observed at approx. 68°. At the concentration in which it exists in intact SC, cholesterol also had only a minimal effect on D lip, but was necessary to suppress H II phase formation within the fatty acids and ensure an Lβ structure. All lipid mixtures that had an L β structure presented a diffusional barrier approx. 1 order of magnitude greater than that of an unstructured, isotropic lipid mixture. H II structures formed at cholesterol/fatty acid proportions less than approx 8: 92 mol% and appeared more permeable than L β ones. All the results indicate that the diffusional barrier within the model lipid mixtures is guaranteed essentially by the presence of an L β phase. Although the ceramides and cholesterol exert no intrinsic influence on the magnitude of D lip, their presence in necessary for the existence of an L β phase at 33° that is free of both crystalline cholesterol and H II character.
角质层脂质多态性的氘核磁共振研究。
DOI：
10.1016/0005-2736(91)90209-q
发表时间：
1991
期刊：
Biochimica et biophysica acta
影响因子：
--
作者：
Abraham,W;Downing,DT
通讯作者：
Downing,DT