中药复方和某种植物分泌液对脂质过氧化的抑制作用

利用发光测量法,研究了中药复方、植物分泌液(SL)和植物分泌液复方(SLIV)对Fe2+-亚麻油酸-BSA(牛血清白蛋白)和Fe2+-脑勺浆两个离体体系产生的脂质过氧化(LPO)有抑制作用,抑制程度与用药浓度有关.将中药复方应用于辐照模型,结果表明7Gy的γ射线辐照后小白鼠全血硒谷胱甘肽过氧化物酶(SeGSH-Px)活性降低,恢复缓慢,脑组织脂质过氧化加剧,而事先喂饲中药复方能显著提高SeGSH-Px水平,加速其活力恢复,增强脑组织抗氧化能力;将SL和SLIV应用于脑缺血重灌模型,结果显示沙土鼠脑缺血重灌后全血SeGSH-Px活力下降,血浆MDA上升,SeGSH-Px/MDA值降低,脑组织抗氧化能力下降,而事先喂饲SL、SLIV上述结果正相反,能明显提高机体的抗LPO能力.     

掺铋离子BaO-B203玻璃的制备及其近红外发光性能的研究

采用高温熔融法制备了掺Bi离子的BaO—B203玻璃,测定了样品玻璃的近红外以及可见光区的激发、发射谱、荧光衰减曲线以及Raman光谱．在808nm波长光的激发下,在掺Bi离子的BaO—B203玻璃中发现了近红外发光现象．且存在多个发光峰．讨论了玻璃网络结构对Bi离子发光的影响,对其发光机理进行了初步的探讨．     

海红果渣总黄酮的体外抗氧化活性

研究了海红果渣总黄酮(TFMM)的体外抗氧化作用,测定了TFMM对油脂过氧化、脱氧核糖氧化损伤的抑制作用以及对超氧阴离子(O2-)的清除作用,并与BHT比较.结果显示,TFMM对脂质过氧化以及脱氧核糖氧化损伤有明显的抑制作用,对超氧阴离子(O2-)有较强的清除作用,效果明显优于同浓度的BHT.且随着海红果总黄酮添加量的增加,对脂质过氧化、脱氧核糖氧化损伤的抑制作用以及超氧阴离子(O2-)的清除抑制作用也随之增强.     

一些含-CH2CH2N(CH3或C2H5)2基团的药物对辐照红细胞膜中硫代巴比妥酸反应物及超弱化学发光强度的影响

用硫代巴比妥酸反应的荧光分析法和超微弱发光法检测了十种含—CH_2CH_2N(CH_3或C_2H_5).基团的临床应用药物对辐照膜脂过氧化的影响,结果表明绝大多数被试药物有较强的抗膜脂过氧化作用.此外,黄嘌吟-黄嘌吟氧化酶系统的实验表明部分被试药物具有较强的减少O_2的能力.对药物结构与其抗膜脂过氧化效率之间的关系进行了初步探讨,结果提示:具有多元环及一正电中心的—CH_2CH_2N(CH_3或C_2H_5)_2化合物可能多为膜脂过氧化的抑制物.     

蜂毒肽与二元脂膜相互作用过程的单分子运动行为

蜂毒肽等抗菌肽可通过破坏细菌的细胞膜而直接杀灭细菌,因此它的杀菌功能具有高效、广谱和不易产生耐药性等特点,并被认为有望能从根本上解决目前正严重威胁人类健康的抗生素耐药性问题.然而,抗菌肽通过增强细胞膜的通透性来实现杀菌的分子机制至今尚不清楚.本文结合单分子荧光追踪技术和分子动力学模拟,从单分子运动的角度对蜂毒肽与二元脂质细胞膜的界面相互作用过程进行了研究.结果表明,相较于其他大多数脂分子而言、部分脂分子在膜内的扩散速率会由于蜂毒肽的吸附、聚集、插膜成孔等扰动行为发生显著降低;而蜂毒肽倾向于作用在多组分脂膜相畴的边界处,干扰并降低脂膜相分离的程度,进而降低相边界对脂质分子扩散运动的限制.本工作阐明了蜂毒肽的膜作用活性对脂分子运动行为和脂膜相行为的影响、以及三者之间的关联.这些结果对于从单分子运动行为的角度来探索抗菌肽生物活性的分子机制和开发新型抗菌药物具有重要的指导意义.     

水中流光放电流光丝的再发光和暂停行为

水中流光放电是研究水中放电基本物理、化学过程的主要研究对象.本文利用四分幅超高速相机、采用针-板电极结构、在20—800μS/cm水电导率范围内研究了水中微秒脉冲流光放电流光丝的再发光和暂停行为,探讨了高水电导率下观测不到流光丝的再发光的原因.结果发现:再发光在不同的流光丝之间交替发生并存在两种模式:一种为整根丝熄灭后再发光;一种为只有先端部分发光熄灭随后恢复发光.随着水电导率的增大,观测到流光丝的再发光现象的频度急剧减小, 540μS/cm水电导率时降到零;在20—800μS/cm水电导率条件下都可观测到流光丝伴生冲击波串分段现象,冲击波串分段现象的出现频度在65%以上,表明在20—800μS/cm水电导率条件下流光丝的暂停是一种普遍行为.通过测量两段冲击波的半径差得到流光的暂停时间平均为157 ns,几乎不受水电导率的影响;随着水电导率的增大,流光丝的发光强度显著增大,水电导率大于350μS/cm时,流光丝暂停期间内流光丝的光强度无法衰减到相机分辨水平以下,在相机获得的发光图像上看上去是持续发光的,难以分辨出流光丝"熄灭-再发光"过程.     

带电多孔二氧化硅纳米颗粒在硫醇/磷脂混合双层膜上的非特异性吸附

制备了表面带阴/阳离子的多孔二氧化硅纳米颗粒, 通过QCM-D研究了颗粒在不同pH值环境下与磷脂膜的非特异性吸附情况. 结果表明, NH₂-MSN 在4–8的pH值范围内与磷脂膜相互吸引, 而COOH-MSN由于与磷脂膜的电性始终保持一致而无法发生吸附现象. 本研究能够帮助理解和预测纳米颗粒与细胞膜间的相互作用, 为药物输运提供载体, 有助于多孔二氧化硅纳米颗粒在药物输运体系中的应用. 关键词： 多孔二氧化硅纳米颗粒 磷脂膜 非特异性吸附 QCM-D     

场致发光理论(一)

1936年,Destriau发现悬浮在绝缘介质中的ZnS—Cu粉末在交变电场作用下发光,这称为Destriau效应,或本征场致发光。这篇报告的作者总结了自1936年以来对这一现象所观测到的二十种比较重要的实验结果,并简单回顾了对这一现象所作的一些比较典型的理论解释。作者认为,当前对场致发光过程的物理解释仍然是很不清楚的。     

以蓝色发光材料DPVBi为基质的白色发光器件

白色有机发光器件是实现彩色平板显示的重要方案之一。利用蓝色发光材料DPVBi[4，4′—(2，2—苯乙烯基)—1，1′—联苯]掺杂红光染料DCJTB[4—氰甲烯基—2—叔丁基—6—(1，1，7，7—四甲基久洛尼定基—9—烯炔基—4H—吡喃)]作发光层制备了白色发光器件。研究了DPVBi掺杂不同浓度IDCJTB薄膜的光致发光性质，根据光致发光结果，制备了以DPVBi掺杂不同浓度DCJTB作发光层的电致发光器件，其结构为ITO／GuPc／NPB／DPVBi：DCJTB／Alq3／LiF／Al。当DCJTB质量分数为0．0008时，器件实现了白色发光(色度x=0．25，y=0．32)，电致发光和光致发光的掺杂比例基本相符，表明器件的白色发光主要是由基质DPVBi向掺杂剂DCJTB的能量传递产生的。研究还发现：白色器件随电压升高，光谱中蓝色成分相对于红色成分的比例略有增加，文章对此现象进行了分析。该白光器件在14V时达到最高亮度7822cd／cm^2，在20mA／cm^2电流密度下的亮度为-489cd／cm^2，最大流明效率为1．75lm／W。     

固态阴极射线发光的发现

通过分层优化方案，采用有机场致发光材料，发现了一种新的激发发光方式，即固态阴极射线发光（solid state cathodoluminescence，简称SSCL），文章主要介绍了固态阴极射线发光的发现历史、发光现象的辨认、发光现象的普适性考察以及其良好的发展前景．     

A Novel Squarylium Dye for Monitoring Oxidative Processes in Lipid Membranes

A novel squaraine probe SQ-1 has been found to be appropriate for monitoring the peroxidation processes in membrane systems. Formation of free radicals was triggered by methemoglobin (metHb) or cytochrome c (cyt c) binding to the model lipid membranes composed of zwitterionic lipid phosphatidylcholine (PC) and anionic lipid cardiolipin (CL). Protein association with the lipid vesicles was followed by drastic quenching of SQ-1 fluorescence. The observed spectral changes were suppressed in the presence of free radical scavengers, butylated hydroxytoluene (BHT) and thiourea (TM) suggesting that SQ-1 decolorization can be attributed to its reactions with lipid radicals.     

Ultrasound-induced membrane lipid peroxidation and cell damage of Escherichia coli in the presence of non-woven TiO2 fabrics

A non-woven titanium dioxide (TiO₂) fabric was applied to disinfection by ultrasound (US) irradiation, and the disinfection efficiency and lipid peroxidation of Escherichia coli (E. coli) cell membrane were evaluated to investigate the killing process. The addition of non-woven TiO₂ fabric enhanced hydroxyl (OH) radical generation and disinfection efficiency. Judging from the disinfection experiments using glutathione or t-butanol as a radical scavenger, the OH radical played a major role in cell killing in sonodynamic disinfection with non-woven TiO₂ fabric. Moreover, to understand the detailed killing process, damage to cell membrane was also evaluated using a diphenyl-1-pyrenylphosphine (DPPP) fluorescent probe, which detects the membrane’s lipid peroxidation. The addition of non-woven TiO₂ fabric aggravated this peroxidation. This aggravation was caused by the OH radical according to an assay using a radical scavenger. From these results, it was concluded that non-woven TiO₂ fabric as a sonocatalyst promoted peroxidation of the polyunsaturated phospholipid component of the lipid membrane initially and induced a major disorder in the E. coli cell membrane under US irradiation.     

Effect of cryopreservation on the structural and functional integrity of cell membranes of sugarcane (Saccharum sp.) embryogenic calluses

In this paper, we investigated if the differences consistently noted in survival and plantlet production between cryopreserved and non-cryopreserved, control sugarcane embryogenic calluses were related to modifications induced during cryopreservation in the structural and functional integrity of cell membranes. For this, the evolution of electrolyte leakage, lipid peroxidation products and cell membrane protein contents was measured during 5 d after cryopreservation. Differences between control and frozen calluses were observed only during the first 2 (electrolyte leakage) or 3 d (lipid peroxidation products and membrane protein content) after freezing. It was not possible to link these differences with the differences noted in survival and plant production between control and cryopreserved calluses. Additional studies are thus needed to elucidate which biochemical factors, linked to survival and plantlet regeneration, are affected by cryopreservation.     

Novel benzanthrone aminoderivatives for membrane studies

The potential of novel benzanthrone aminoderivatives to trace the changes in physicochemical properties of lipid bilayer has been evaluated. Binding of the dyes to the lipid bilayers composed of zwitterionic phospholipid phosphatidylcholine (PC) and its mixtures with anionic phospholipid cardiolipin (CL) and cholesterol (Chol) was followed by significant quantum yield increase with small blue shift of emission maximum. Analysis of partition coefficients of the dyes under study showed that all aminobenzanthrones possess high lipid-associating ability. The dyes A8 and AM2 proved to be sensitive to the variations in membrane chemical composition responding to the changes in bilayer hydration induced by CL and Chol.     

A New Fluorescent Squaraine Probe for the Measurement of Membrane Polarity

The present study was undertaken to evaluate the sensitivity of newly synthesized squaraine dye 1 to the changes in lipid bilayer physical properties and compared it with the well-known dye 2. Partitioning of the dye 1 into lipid bilayer was found to be followed by significant increase of its fluorescence intensity and red-shift of emission maximum, while intensity of the dye 2 fluorescence increased only slightly on going from aqueous to lipidic environment. This suggests that dye 1 is more sensitive to the changes in membrane properties as compared to dye 2. Partition coefficients of the dye 1 have been determined for the model membranes composed of zwitterionic phospholipid phosphatidylcholine (PC) and its mixtures with positively charged detergent cetyltrimethylammonium bromide (CTAB), anionic phospholipid cardiolipin (CL), and sterol (Chol). The spectral responses of the dye 1 in different liposome media proved to correlate with the increase of bilayer polarity induced by Chol and CL or its decrease caused by CTAB. It was concluded that dye 1 can be used as fluorescent probe for examining membrane-related processes.     

Using the U-120 cyclotron to study the effect of 30 MeV alpha particles on a liposome membrane

We studied the effect of α particles with energies 30.5 MeV, emitted from the 120-cm cyclotron at Skobeltsyn Research Institute of Nuclear Physics, MSU, on artificial membrane systems (liposomes) to simulate the effects of ionizing galactic cosmic rays on biological subjects. The start of low-level lipid peroxidation, accompanied by a change in the ordering of fatty acid residues in a part of the membrane remote from β-carotene molecules, was observed after irradiation by α-particles. The presented method proved to be quite effective and reliable.     

Examining Protein-Lipid Interactions in Model Systems with a New Squarylium Fluorescent Dye

The applicability of newly synthesized squarylium dye Sq to probing the changes in physical characteristics of lipid bilayer on the formation of protein-lipid complexes has been evaluated. Lipid vesicles composed of zwitterionic phospholipid phosphatidylcholine (PC) and its mixtures with positively charged detergent cetyltrimethylammonium bromide (CTAB), anionic phospholipid cardiolipin (CL), and cholesterol (Chol) were employed as lipid component of model membrane systems while protein constituent was represented by lysozyme (Lz). Fluorescence intensity of Sq was found to decrease on Lz association with lipid bilayer. This effect was observed in all kinds of model systems suggesting that Sq is sensitive to modification of lipid bilayer physical properties on hydrophobic protein-lipid interactions. It was found that Sq spectral response to variations in Chol content depends on relative contributions of electrostatic and hydrophobic components of Lz-membrane binding.     

EPR study of the toxicological effects of gas-phase cigarette smoke and the protective effects of grape seed extract on the mitochondrial membrane

Electron paramagnetic resonance spin trapping and spin labeling techniques were used to study the effects of grape seed extract on the biophysical propertiers of the mitochondrial membrane exposed to gas-phase cigarette smoke. The spin trapping results indicated that grape seed extract can effectively scavenge free radicals in cigarette smoke and the lipid free radicals generated from the lipid peroxidation of mitochondrial membrane caused by gas-phase cigarette smoke. The spin labeling results showed that grape seed extract can protect the mitochondrial membrane from the toxicological damage caused by gas-phase cigarette smoke.     

The effect of high-voltage electrostatic field (HVEF) on aged rice (Oryza sativa L.) seeds vigor and lipid peroxidation of seedlings

The study of the effect of high-voltage electrostatic field (HVEF) on plant seeds has been becoming one of the popular issues in electrostatic biology since the influence of HVEF on growing plants was observed early in 1980s and a few studies showed that HVEF could increase seeds activity. In this study the aged rice seeds were treated in HVEF, and their vitality and associated physiological variables such as membrane lipid peroxidation and the protective enzyme system, such as superoxide dismutase (SOD: EC 1.15.1.1), peroxidase (POD: EC 1.11.1.7) and catalase (CAT: EC 1.11.1.6) were also investigated. The results showed that the activity index of aged rice seeds was significantly increased, and the leakage conductivity was decreased with the appropriate HVEF treatment. The treatment also elevated the activity of SOD, POD and CAT, which improved the penetrating capability of membrane, and adjusted the level of lipid peroxidation and lowered the content of malondialdehyde (MDA). We concluded that HVEF could elevate aged rice seeds vigor and improve membrane system of aged rice seedlings, and the treatment for 55 min was better than that of 30 min.