皮肤的生理特点与透皮吸收

皮肤组织具有自我更新的能力，但表皮层内没有血供，营养状态较差。皮肤的衰老与年龄、激素水平、日晒等因素有关，氧自由基在皮肤老化的过程中起重要作用。表皮角质层的水分主要以结合态存在于角质细胞间的脂质结构中。脂质中的极性成分、非极性成分与水分子一起组成乳化体系，在一定条件下保持动态平衡。表皮的角质层是透皮吸收的主要屏障，氮酮等物质具有促进透皮吸收的作用。     

脂肪酸多相脂质体与癌细胞膜相互作用的ESR谱研究

用电子自旋共振(ESR)技术对液晶态多烯脂肪酸多相脂质体与癌细胞膜相互作用进行了研究. 并探讨了其在抑制和杀伤癌细胞过程中可能具有的生物学意义.实验发现：油酸多相脂质体的影响使自旋标记物在Ec腹水肝癌细胞膜上的强固定化作用减弱, 弱固定化作用增强,使自旋标记物运动自由度增加.亚油酸多相脂质体的影响使自旋标记物在乳腺癌细胞膜上的强固定化作用增强, 弱固定化作用减弱,使自旋标记物运动自由度受到限制.蓖麻酸多相脂质体的影响使自旋标记物在S₁₈₀实体瘤细胞膜上的强固定化作用增强, 弱固定化作用减弱,使自旋标记物运动自由度受到限制.结果表明,多烯脂肪酸多相脂质体作用于膜蛋白引起了膜蛋白构象的变化.     

外源脂肪酸对莱氏衣原体膜流动性的影响——电子自旋共振与荧光偏振研究

生物膜类脂的物理性质直接影响膜的生理功能,膜的流动动性是反映膜脂物理状态的一个重要特征.本文采用电子自旋共振波谱及荧光偏振技术研究油酸,硬脂酸以及油酸和棕榈酸的混合物渗入莱氏衣原体膜后对膜流动性的影响.结果表明,上述外源脂肪酸均能增加膜的流动性,其中以油酸渗入膜后最为显著.油酸中双键的作用不仅仅局限于双键所在碳原子附近,而且能使整个膜脂双层各个层次上流动性都有增加.对于用荧光偏振和自旋标记顺磁共振二种技术所获得结果的异同也进行了初步讨论.     

渗透促进剂对5－DSA标记裸鼠皮肤角质层影响的ESR研究

通过测定５－唑烷氮氧自由基硬脂酸（５－ＤＳＡ）标记裸鼠皮肤角质层的电子自旋共振（ＥＳＲ）谱,研究某些渗透促进剂如月桂酮（ＡＺ）、油酸（ＯＡ）、丙二醇（ＰＧ）、二甲基亚砜（ＤＭＳＯ）等对裸鼠皮肤角质层的影响。促渗剂处理皮肤后,标记物序参数降低,各向同性超精细分裂偶合常数增大,前者表明保渗剂能够引起皮肤角质层细胞间脂质排列有序性降低,流动性增大;后者表明标记物周围脂质区域极性增大。     

渗透促进剂对5－DSA标记裸鼠皮肤角质层影响的ESR研究

通过测定５－恶唑烷氮氧自由基硬脂酸（５－ＤＳＡ）标记裸鼠皮肤角质层的电子自旋共振（ＥＳＲ）谱,研究某些渗透促进剂如ＡＺ、油酸（ＯＡ）、丙二醇（ＰＧ）、二甲基亚砜（ＤＭＳＯ）等对裸鼠皮肤角质层的影响。促渗剂处理皮肤后,标记物序参数降低,各向同性超精细分裂偶合常数增大,前者表明促渗剂能够引起皮肤角质层细胞间脂质排列有序性降低,流动性增大;后者表明标记物周围脂质区域极性增大。     

吲哚美辛水凝胶贴剂小鼠体外透皮性能研究

目的：通过研究不同促透剂对吲哚关辛水凝胶贴剂透皮性能的影响,遴选在特定栽药剂量时具有最佳促透效果的促透剂,并与市售贴剂进行比较,对吲哚美辛水凝胶贴剂的体外透皮性能进行评价。方法：采用改良Franz透皮扩散池,以离体小鼠背部皮肤为透皮屏障,在最佳载药量选用不同浓度的氮酮、油酸、丙二醇以及三者组成的二元或三元组合为促透剂,在规定时间点测定吲哚美辛的累积透过百分率以及单位面积累积透过量。结果：与空白对照组相比,当氮酮与油酸单独应用时,二者均没有明显的促透作用;当选用二元促透剂联合应用时,油酸与丙二醇联用能够明显促进吲哚美辛的经皮渗透（P〈0．05）;当选用三元促透剂时促透效果更好,单位面积累积透过量最高可达234．4μg·cm^-2,24h内药物累积透过百分率明显高于市售贴剂。结论：氮酮、油酸、丙二醇三者联合应用可作为吲哚关辛贴剂的理想促透剂。吲哚关辛水凝胶贴剂是具有应用价值的新型经皮控释制剂。     

NMR在膜研究中的应用(上)

一、膜的结构和动力学生物膜主要是由膜蛋白和类脂组成的,大多数生物膜的类脂成分主要是磷脂。磷脂水悬浮液表现出天然膜的许多性质,所以在NMR实验中它被广泛作为生物膜的模型予以研究。磷脂悬浮液是以多相形式存在的,这取决于温度和水的含量。在生物膜模型中起重要作用的是凝胶相和液晶相。在凝胶相,分子的局部运动很慢,在NMR时标上,分子间和分子内的偶极矩相互作用没被有效地平均,所以NMR的谱线很宽、缺乏明显的特征。而在液晶相,分子局部运动受到的限     

自旋标记法研究不同因素对嗜盐菌紫膜类脂物性的影响

本文用自旋标记方法研究了不同的pH和盐介质对光照前后嗜盐菌(H.halobium)紫膜类脂的影响.在低盐介质中,紫膜类脂序参数S的大小依次为pH2.5>pH7.0>pH12.0:旋转相关时间τ均在10~(-a)sec范围之内.pH12.0的暗适应和光适应悬液的ESR波谱十分相似,其它的ESR波谱均为暗适应>光适应.悬浮于Triton X-100中的紫膜的序参数最小,τ_e值在10~(-9)--10~(-10)sec之间;但其暗适应和光适应的ESR波谱仍有差别.在高盐介质中,紫膜类脂序参数均大于低盐介质,结构最为刚硬.实验表明类脂的序态变化与bR分子的构象改变有密切关系.     

微针阵列用于生物大分子药物的递送

生物大分子药物难以跨过皮肤的角质层屏障,而微针作为一种微创、无痛、高效的经皮给药方式,能有效破解大分子药物透皮速率和吸收量低下的难题.本文详细综述了微针阵列技术在各类生物大分子药物经皮递送中的应用进展,包括单独微针阵列(固体实心微针、空心微针、涂层微针和可溶性微针)以及微针与其他制剂技术(如微粒给药系统)、医疗器械和智能释药系统等结合对大分子药物的促渗作用和控释作用.同时对微针用于大分子药物递送领域目前面临的问题、发展前景等作出分析.     

综述——纳米材料与药物输递：经皮给药中纳米制剂与皮肤的质构效关系

皮肤是人体最大的器官,也为药物的递送提供了重要途径。经皮给药是药物以皮肤为媒介,透过皮肤吸收的途径。因此,皮肤角质层是经皮给药的最大限速障碍。纳米经皮给药系统,具有提高透皮效率、缓释性、避免药物肝首过效应、减少副作用等优点,是通过纳米制剂与皮肤组织之间的相互作用实现的。其中,纳米制剂的结构和组分与其发挥皮肤促渗效用密切相关。对纳米制剂与皮肤质构效关系深入透彻的了解,有助于新型透皮纳米制剂的设计,并利用综合手段构建安全、高效、实用的经皮给药系统。     

Lipid protein interactions in mitochondria. VIII. Effect of general anesthetics on the mobility of spin labels in lipid vesticles and mitochondrial membranes

We have studied the effect of general anesthetics on the mobility of two stearic acid spin labels (5-doxyl stearic acid and 16-doxyl stearic acid) in bovine heart mitochondria and in phospholipid vesicles made from either mitochondrial lipids or commercial soybean phospholipids. The general anesthetics used include nonpolar compounds (alcohols, halothane, pentrane, diethyl ether, chloroform) and the amphipathic compound, ketamine. All anesthetics tested increase the mobility of the spin labels in phospholipid vesicles to a limited extent up to a concentration where the ESR spectra become those of free spin labels. On the other hand, anesthetics have a pronounced effect on mitochondrial membranes at concentrations as low as those known to produce general anesthesia; the effect is lower near the bilayer surface (5-doxyl stearic acid) and very strong in the bilayer core (16-doxyl stearic acid). The effects of anesthetics are mimicked by the detergent, Triton X-100. We suggest that the discrepancy between the action of anesthetics in mobilizing the spin labels in lipid vesicles and in membranes results from labilization of lipid protein interactions.     

ESR as a valuable tool for the investigation of the dynamics of EPC and EPC/cholesterol liposomes containing a carboranyl-nucleoside intended for BNCT

Electron Spin Resonance (ESR) spectroscopy of long-chain nitroxides (5-, 7-, and 16-doxyl stearic acid) has been used to evaluate the perturbations induced by beta-5-o-carboranyl-2'-deoxyuridine (CDU) on the structure and dynamics of egg phosphatidylcholine (EPC) and EPC/cholesterol liposomes. Loaded liposomes are intended for the use in Boron Neutron Capture Therapy (BNCT). From a detailed analysis of the motional and order parameters determining the ESR line shape as a function of temperature and of CDU content in liposomes, an increased order and a hindered motion of the phospholipid membranes resulted in the presence of increasing CDU concentration. This occurred particularly at the liposome surface level. Both higher ordering and increased rigidity of the membrane lipids were the result of the constraints exerted by the embedded carboranyl-nucleoside.     

Ischemia/reperfusion-induced changes in membrane fluidity characteristics of brain capillary endothelial cells and its prevention by liposomal-incorporated superoxide dismutase.

The effect of global cerebral ischemia and reperfusion on cerebral capillary endothelial cell membrane fluidity was examined using electron paramagnetic resonance techniques following 8 minutes of global ischemia and 15 minutes of blood reperfusion. The luminal surface of the cerebral vasculature was perfused with a series of doxyl stearic acid reporters (5-, 12-, 16-doxyl stearic acid) which differ in the site of attachment of the nitroxide free radical on the fatty acid chain. Each doxyl stearic acid reports on membrane fluidity characteristics from different depths within the membrane. Ischemia/reperfusion produced a membrane ordering that was markedly dependent on intramembrane location, and was consistent with changes previously associated with lipid peroxidation. The effect of ischemia/reperfusion on membrane fluidity was maximal in the membrane environment reported by 12-doxyl stearic acid (12-DS). The utilization of a liposomal system was shown to enhance superoxide dismutase delivery to cerebral tissues as well as attenuating the change in membrane order seen following reperfusion-induced lipid peroxidation.     

Comparison of perturbation effect of propranolol, verapamil, chlorpromazine and carbisocaine on lecithin liposomes and brain total lipid liposomes. An EPR spectroscopy study.

Effect of verapamil, propranolol, chlorpromazine and carbisocaine on dynamics and/or order of liposomes (perturbation effect), prepared from different molar ratios of lecithin (PC) and rat brain total lipids (TL) was studied by EPR spectroscopy using spin probes 16-doxyl stearic acid and 14-doxyl phosphatidylcholine. The PC liposomes had higher dynamics and/or lower order than the TL liposomes. The perturbation effect of the drugs depended largely on the lipid composition of the liposomes. The drugs at the drug/lipid molar ratios from 0.1 to 1 increased membrane dynamics and/or decreased membrane order. The drugs had the most pronounced perturbation effect in the liposomes prepared from brain total lipids. The effect of the drugs decreased with decreasing the TL/PC ratio in the liposomes and was lowest, almost diminished, in the PC liposomes. Increasing concentration of the drugs decreased the difference between the dynamics and/or order of the PC and TL liposomes and so eliminated the influence of lipid composition on these membrane parameters. The results emphasize the role of lipid composition in studies concerning drug-lipid interactions in model and biological membranes.     

Temperature-induced changes of spin-labelled radioactive lipids in isolated guinea pig liver microsomal membranes before and in mitochondrial membranes after their translocation.

Lipids of isolated guinea pig liver microsomal membranes were labelled biosynthetically with isomeric doxyl stearic acid and temperature-induced changes of these membranes were studied by electron spin resonance. A noticeable discontinuity was detected at 10--12 degree C with 12- or 16-doxyl stearic acid containing membrane lipids which was attributed to the spin-labelled lipid--microsomal membrane protein interactions since no such discontinuity was detected in liposomes prepared from total lipid extracts of microsomal membranes. When microsomal membranes containing radioactive isomeric spin-labelled lipids were incubated with unlabelled mitochondria, reisolated mitochondrial membranes contained translocated radioactive isomeric spin-labelled lipids. Temperature-induced changes in these membranes showed no discontinuity with either isomeric doxyl stearic acid derivative, establishing a difference in the environment of translocated lipids in the membrane donor compared with that in the membrane acceptor. Microsomal membranes recovered from translocation experiments showed the same behaviour as the original membranes and exhibited the same discontinuity at 10--12 degree C, establishing that the translocation incubation itself did not alter the spin-labelled lipid interaction within these membranes. Studies of the loss of paramagnetism of spin-labelled lipids in microsomal membranes before and in mitochondrial membranes after their translocation showed a significant difference and suggested that both the outer and the inner mitochondrial membranes might have been involved.     

ESR as a valuable tool for the investigation of the dynamics of EPC and EPC/cholesterol liposomes containing a carboranyl-nucleoside intended for BNCT

Electron Spin Resonance (ESR) spectroscopy of long-chain nitroxides (5-, 7-, and 16-doxyl stearic acid) has been used to evaluate the perturbations induced by β-5-o-carboranyl-2′-deoxyuridine (CDU) on the structure and dynamics of egg phosphatidylcholine (EPC) and EPC/cholesterol liposomes. Loaded liposomes are intended for the use in Boron Neutron Capture Therapy (BNCT). From a detailed analysis of the motional and order parameters determining the ESR line shape as a function of temperature and of CDU content in liposomes, an increased order and a hindered motion of the phospholipid membranes resulted in the presence of increasing CDU concentration. This occurred particularly at the liposome surface level. Both higher ordering and increased rigidity of the membrane lipids were the result of the constraints exerted by the embedded carboranyl-nucleoside.     

Electron spin resonance studies of lipid fluidity changes in membranes of an uncoupler-resistant mutant of Escherichia coli

The fluidity of the lipids in membrane preparations from a mutant of Escherichia coli resistant to the uncoupler CCCP, grown at different temperatures with and without CCCP, was examined by electron spin resonance using the spin probe 5-doxyl stearic acid. The fluidity of the membrane lipids at the growth temperature, as estimated using electron spin resonance, was less in cells grown at lower temperatures. Precise homeoviscous adaptation was not observed. Growth in the presence of CCCP resulted in a decrease in membrane lipid fluidity, particularly in the inner (cytoplasmic) membrane. There was no change in the proportion of phosphatidylethanolamine, phosphatidylglycerol and cardiolipin in the cell envelope. However, there was an increase in the proportion of unsaturated fatty acids in membranes from cells grown with uncoupler. This was reflected in the increased fluidity of the lipids extracted from these membranes. This result is contrary to that expected from measurements of the fluidity of the lipid in these membranes. The decreased fluidity of the lipid in these membranes may be a consequence of the observed increase in the ratio of protein to phospholipid.     

Pseudopregnancy-dependent changes in rat ovarian LH/hCG receptors in relation to membrane lipid fluidity

The specific binding of [125I] hCG to ovarian membrane preparations as well as membrane fluidity have been investigated in immature rats during hormonally-induced pseudopregnancy. Membrane fluidity was monitored either by fluorescence polarization analysis of 1,6-diphenyl-1,3,5-hexatriene or by electron spin resonance of 16-, 12-, 5-doxyl stearic acid and CAT 16. A significant positive correlation was found between membrane lipid rigidity and the number of LH/hCG receptors. Luteinization of the ovary induced mobility of molecules in the hydrophobic membrane part at about the C16 carbon level. The changes in rigidity of membrane lipid were the apparent result of alterations in the cholesterol to phospholipids ratio. The results suggest that the increased rigidity of membrane lipid during pseudopregnancy may maximally expose ovarian LH/hCG receptors maintained in a cryptic form.     

白内障形成过程中晶状体细胞膜上脂类与蛋白质氧化的时间差异性

用马来酰亚胺及５恶唑氮氧自由基硬脂酸分别标记晶状体细胞膜中蛋白质及脂类,以电子自旋共振方法研究在三硝基甲苯、亚硒酸钠、半乳糖、平阳霉素及紫外线等白内障诱发剂作用下,晶状体细胞膜的氧化损伤变化。结果发现当晶状体细胞暴露于空气中时,晶状体细胞膜脂类氧化早于蛋白质的氧化;在五种白内障诱发剂作用下,均是如此．这说明白内障的形成首先是由膜中脂类氧化所引起。     

Effect of fatty acids and monoglycerides on permeability of lipid bilayer

The effect of fatty acids and monoglycerides on barrier properties of liposomal membranes prepared from egg phosphatidylcholine was investigated. The incorporation of these lipids as liposomal membrane components induced the alteration of the permeability to less permeable liposomally entrapped drugs, sulfanilic acid and procainamide ethobromide (PAEB). Monoolein caused greatly increased permeability of both drugs and unsaturated fatty acids markedly enhanced the release rate of PAEB, while saturated fatty acids caused a small increase in the release rate.Electron spin resonance (ESR) investigation with 5-nitroxide stearic acid showed that fatty acids disordered the hydrophobic region of the lipid bilayer and the disordering effect of unsaturated fatty acids was greater than that of saturated ones. It was demonstrated that the incorporated fatty acids and monoglycerides interacted with the polar region of the membranes by ESR study with cholestane label and ¹H-NMR study. These results indicated that the increase in the membrane permeability caused by fatty acids and monoglycerides associated with the disorder in the membranes' interior and the interaction of the incorporated lipid with the polar head group of phospholipid.