超声对细胞膜通透性的影响及应用

适当参数的超声，使细胞膜发生可以修复的损伤，使细胞膜的通透性提高，从而使细胞内的物流释放到细胞外，细胞外的物质进入细胞内，这一现象可以用于释放代谢产物或中间产物，基因转导，强化化学方法治疗肿瘤等方面。  

脉冲微波辐照影响心肌细胞膜蛋白构象及其机制的研究

应用显微傅里叶变换红外光谱技术研究了脉冲微波辐照对心肌细胞膜蛋白质构象、功能的影响和相关分子机制.结果表明,辐照可对心肌细胞的细胞膜蛋白质结构产生明显影响.细胞膜脂质中-CH2-、磷脂结构中G=O、蛋白质酰胺Ⅰ,Ⅱ带的伸缩振动峰消失或位移.辐照后心肌细胞膜蛋白质二级结构也出现明显变化,α-螺旋和β-折叠结构减少,二级结构无序化程度增加.上述变化均与辐照剂量呈正相关.结果提示受脉冲微波辐照后,心肌细胞膜蛋白构象的完整性受损,膜稳定性及流动性下降,膜上多种生物活性结构被破坏,上述变化构成了细胞膜功能丧失、细胞形态和结构损伤、细胞凋亡等病理学效应的生物化学基础.文章首次从蛋白质构象角度阐述了微波辐照对心肌细胞膜损伤的分子病理机制.  

镍、镉对生物膜损伤机理的FTIR研究

本文采用傅里叶变换红外（FTIR）漫反射光谱技术，研究比较了镍与镉对人类红细胞膜的联合损伤作用，同时对其作用机制进行了探讨。通过观察分析两金属与红细胞膜作用前后细胞膜红外光谱中1742、1662、1636、1556、1464、1405和1389cm-1等吸收峰的变化，表明两金属离子单独或同时存在均可使膜蛋白质发生变性和不可逆聚合、使膜脂质发生相变以及可能的重金属离子与蛋白质分子中-COOH侧链成盐等分子改变。实验还表明镍、镉对细胞膜的作用机制是类似的，联合作用时两金属离子可能协同引起细胞膜的损伤。  

荧光偏振法研究脉冲电场对酿酒酵母细胞膜流动性影响

以DPH(1,6-二苯基-1,3,5-己三烯)为荧光探剂,采用荧光偏振法探讨了脉冲电场(0～25kV.cm-1,0～266ms)对酿酒酵母细胞膜流动性影响。经5kV.cm-1电场处理后,酿酒酵母细胞膜的流动性显著减小,并且随电场强度和处理时间的增加而减小;通过平板计数法和紫外分光光度计法分别检测了脉冲电场对酿酒酵母细胞存活对数及膜通透性影响。结果显示,5kV.cm-1虽然只能使少量的酵母致死,却能使酵母细胞膜的通透性显著增加,膜流动性显著降低。并且细胞的存活率随电场强度增大而减小,细胞膜的通透性随电场强度增大而增大。这表明细胞膜的流动性降低与细胞膜的通透性升高成正相关,与细胞的存活率成负相关。由此推测脉冲电场在对酿酒酵母灭菌过程中,细胞膜是其作用的一个关键位点,膜流动性减小,细胞膜通透性增强,是细胞死亡的主要原因。  

荧光偏振光谱法探测光动力过程中癌细胞膜的流动性

以DPH作荧光探剂，用荧光偏振光谱法研究了金属酞菁配合物苯硫基钛菁锌（C56H32N8S4Zn）在光动力过程中，不同光照时间对乳腺癌细胞膜流动性的影响。实验结果表明，经光照激发光敏剂金属酞菁后，荧光标记团的偏振度增大，癌细胞膜流动性降低，微黏度升高。说明这是光动力治疗的疗效所在。用酶联免疫检测（MTT法）不同光照时间对细胞存活的影响，结果显示癌细胞最低存活率与膜流动性降低成正相关。这表明光动力过程在一个相近的程度影响癌细胞膜的流动性和增殖，提示光动力过程可能通过影响细胞膜流动性引起细胞增殖变化，即细胞膜是光动力作用的一个位点。  

Application of high-resolution magic-angle spinning NMR spectroscopy to define the cell uptake of MRI contrast agents

A new method, based on proton high-resolution magic-angle spinning ((1)H HR-MAS) NMR spectroscopy, has been employed to study the cell uptake of magnetic resonance imaging contrast agents (MRI-CAs). The method was tested on human red blood cells (HRBC) and white blood cells (HWBC) by using three gadolinium complexes, widely used in diagnostics, Gd-BOPTA, Gd-DTPA, and Gd-DOTA, and the analogous complexes obtained by replacing Gd(III) with Dy(III), Nd(III), and Tb(III) (i.e., complexes isostructural to the ones of gadolinium but acting as shift agents). The method is based on the evaluation of the magnetic effects, line broadening, or induced lanthanide shift (LIS) caused by these complexes on NMR signals of intra- and extracellular water. Since magnetic effects are directly linked to permeability, this method is direct. In all the tests, these magnetic effects were detected for the extracellular water signal only, providing a direct proof that these complexes are not able to cross the cell membrane. Line broadening effects (i.e., the use of gadolinium complexes) only allow qualitative evaluations. On the contrary, LIS effects can be measured with high precision and they can be related to the concentration of the paramagnetic species in the cellular compartments. This is possible because the HR-MAS technique provides the complete elimination of bulk magnetic susceptibility (BMS) shift and the differentiation of extra- and intracellular water signals. Thus with this method, the rapid quantification of the MRI-CA amount inside and outside the cells is actually feasible.  

On the equilibrium equation for a generalized biological membrane energy by using a shape optimization approach

A mechanical equilibrium equation of a vesicle membrane under a generalized elastic bending energy is obtained in this paper. Moreover, the derivation of this equilibrium equation is based on some shape optimization tools. This approach is new and more concise than the tensorial tools used previously for this problem.  

Nuclear magnetic resonance microimaging investigation of membrane electrode assembly of fuel cells: morphology and solvent dynamics

The structure and solvent (water, methanol, etc.) dynamics of a number of fuel membrane electrode assembly (MEA) samples are studied with nuclear magnetic resonance microimaging with spatial resolution of tens of micrometers. The micrometer-scale inhomogeneity of the samples is observed and confirmed with various weighting methods. In particular, diffusion coefficients at different positions in MEA are clearly differentiated. Furthermore, chemical shift selection imaging enables one to investigate the spatial distribution and dynamics of individual chemical groups. These types of information offer us insights into the working principle of fuel cell and pave the way to in situ studies of operating fuel cells.  

Application of ultrasound in preparing pathological sections to reduce processing time

It has been found experimentally that application of sub-mega and low megahertz ultrasound (US) of spatial and temporal averaged intensity I_sata up to 10 W/cm² during the process of preparing pathological sections of the mouse tissue has shortened the processing time from 12 h (without US) to less than half an hour (with US). The experiment has also showed that the processing time reached the shortest for ultrasound f = 200 kHz among the frequencies of 200 kHz, 400 kHz, 600 kHz, 800 kHz and 1 MHz used in this study. It has been proposed that ultrasound inducing non-inertial cavitation enhanced the permeability of cell membrane to liquid. Thus tissue fixation and dehydration were speeded up by application of US.