New insights on the role of ROS in the mechanisms of sonoporation-mediated gene delivery

Reactive oxygen species (ROS) are hypothesized to play a role in the sonoporation mechanisms. Nevertheless, the acoustical phenomenon behind the ROS production as well as the exact mechanisms of ROS action involved in the increased cell membrane permeability are still not fully understood. Therefore, we investigated the key processes occurring at the molecular level in and around microbubbles subjected to ultrasound using computational chemistry methods. To confirm the molecular simulation predictions, we measured the ROS production by exposing SonoVue® microbubbles (MBs) to ultrasound using biological assays. To investigate the role of ROS in cell membrane permeabilization, cells were subjected to ultrasound in presence of MBs and plasmid encoding reporter gene, and the transfection level was assessed using flow cytometry. The molecular simulations showed that under sonoporation conditions, ROS can form inside the MBs. These radicals could easily diffuse through the MB shell toward the surrounding aqueous phase and participate in the permeabilization of nearby cell membranes. Experimental data confirmed that MBs favor spontaneous formation of a host of free radicals where HO was the main ROS species after US exposure. The presence of ROS scavengers/inhibitors during the sonoporation process decreased both the production of ROS and the subsequent transfection level without significant loss of cell viability. In conclusion, the exposure of MBs to ultrasound might be the origin of chemical effects, which play a role in the cell membrane permeabilization and in the in vitro gene delivery when generated in its proximity.     

黄颡鱼属SSR分子鉴定及其遗传多样性

利用13对SSR引物对黄颡鱼属进行遗传多样性和分类研究。结果显示,13对SSR引物中有10对为有效引物,获得93条多态性条带,每对引物扩增条带的数目范围为8~11,扩增片段大小在90~400bp之间,SSR获得的多态性条带所构成各物种的特异性谱系能够用于黄颡鱼属的区分。聚类结果显示,5种黄颡鱼之间的遗传相似系数范围为0.670~1.000,瓦氏黄颡鱼、长须黄颡鱼和中间黄颡鱼亲缘关系较近,之后与光泽黄颡鱼聚为一支,普通黄颡鱼与其它物种差异最大。黄颡鱼属遗传多样性分析结果显示5种黄颡鱼遗传多样性处于水平较高,这将有助于后续深入对黄颡鱼属各物种亲缘关系和系统演化进行分析和理论研究。     

复杂的可编程逻辑器件在可控电抗器中的应用

分析了磁阀式可控电抗器的结构和工作原理,通过直流控制电流控制铁芯的饱和度来调节电抗器的投入容量,采用可控硅和复杂的可编程逻辑器件（ＣＰＬＤ）为其设计了控制装置,实现了电抗器容量的自动连续调节,具有响应速度快、可靠性高的特点,并在电网无功补偿中得到了较好的应用．     

浙江省不同演替阶段的低海拔次生林植物功能群结构的比较研究

选取浙江省低海拔地区的16个次生林样地并调查其中胸径（DBH）≥1 cm的木本植物.通过观察群落外貌,结合数量分类方法（TWINSPAN）和排序方法（DCA）,将这些样地划分为4种演替阶段的森林类型（马尾松林,马尾松针阔叶混交林,演替早期常绿阔叶林,演替中期常绿阔叶林）.分析了不同演替阶段的次生林群落物种多样性和植物功能群结构组成变化.结果显示：（1） 适度择伐进入采伐期的马尾松可加速整个群落向常绿阔叶林演替;（2） 随着演替的进行,物种丰富度、Shannon Wiener指数、Simpson指数和Pielou均匀度指数均呈现增加趋势;（3） 按生活型、生长型、叶的生活期和对光的耐受性这4种功能群划分,所有样地分别以小高位芽植物和中高位芽植物、乔木和灌木或小乔木、常绿植物和耐阴植物占优;（4） 随着演替的进行,功能群结构比例呈现先降后升再降的是矮高位芽植物,先降后升的为小高位芽植物,呈现先升后降的为大高位芽植物、灌木、乔木、小乔木、常绿植物、阴性植物呈现上升趋势,落叶植物和阳性植物呈现下降趋势,而中高位芽植物、灌木或小乔木、耐阴植物则维持相对恒定的比例.     

Quantitative analysis of oxidative DNA damage induced by high-voltage pulsed discharge with cavitation

Pulsed discharge is used for sterilization and disinfection, but the details of the molecular mechanisms remain largely unknown. Since pulsed discharge generates reactive oxygen species (ROS), we analyzed the oxidative DNA damages after pulsed discharge treatment to consider the involvement of ROS in the damaging process. We applied pulsed discharge with cavitation to plasmid DNA molecules and estimated the yields of the damages by agarose gel electrophoresis. The treated DNA contained various oxidative DNA damages, including single and double strand breaks and base lesions. The yields of the damages increased in response to the energy used for pulsed discharge. We also measured the yield of 8-hydroxyguanine (8-OH-G), one of the major oxidative base lesions, in the treated plasmid DNA by mass spectrometry quantitatively and found that the yield of the oxidative base lesion corresponded to the increment of the applied energy. In addition, we observed the involvement of mutM gene, which is responsible for repair of 8-OH-G, in the increased sensitivity of Escherichia coli to pulsed discharge. Therefore, ROS seem to mediate the sterilization ability of pulsed discharge.     

Reactive polymers incorporating silyl enol ether groups. I. synthesis by radical polymerization of 2-(trimethylsiloxy)-butadiene and 2-(tert)-butyldimethylsiloxy butadiene

2-(Trimethylsiloxy)butadiene (TMSBD) and 2-(tert-butyldimethylsiloxy)butadiene (TBMSBD) were copolymerized with styrene (St) and methyl methacrylate (MMA) under free-radical conditions. The obtained polymers were found to contain reactive silyl enol ether groups in a ratio identical to the TMSBD or TBMSBD molar fraction in the copolymer. All investigated samples displayed only 1,4- and 3,4-microstructures. The influence of several experimental factors on the yields, rates of polymerization, microstructures, and copolymer compositions were examined. Monomer reactivity ratios r₁ and r₂ at 60°C were determined from copolymer composition curves at low conversions. The homopolymerization of TBMSBD was also investigated and results were compared with those previously obtained for TMSBD. A slight increase in rates was observed and was rationalized on the basis of the higher viscosity resulting from the structural change in the monomer. Thermal stabilities of the synthesized polymers were investigated by TGA and their glass transition temperatures were determined by DSC. All measurements are compatible with a possible use of TMSBD and TBMSBD copolymers as reactive polymers. © 1996 John Wiley & Sons, Inc.     

Capillary zone electrophoresis with UV-scanning detection for the analysis of metal species and their organic binding partners in biological systems

A capillary zone electrophoretic method with UV-scanning detection for the separation and identification of both free ligands and metal species is presented. The electrophoretic behavior of naturally occurring binding partners such as organic acids and amino acids was studied and compared with their metal-complexes. Copper(II) complexes of citrate and amino acids showed decreased electrophoretic mobilities and altered UV spectra. The optimized method was validated on ultrafiltered cow's milk and human milk samples. In cow's milk six low molecular weight substances, including citrate, orotate, and hippurate, could be separated. Metal supplementation with Cu(II), Ni(II), or Zn(II) decreased not only the citrate peak but also the orotate signal and in the case of copper(II) supplementation a new signal for the copper(II)-citrate complex appeared. In human milk samples various amino acids such as glutamate, phenylalanine, tyrosine, and tryptophan could be identified besides citrate. The electrophoretic mobilites and peak areas of the amino acids were also influenced by the metal supplementation.     

In Vitro Evaluation of the Photoreactivity and Phototoxicity of Natural Polyphenol Antioxidants

Polyphenols are a large family of natural compounds widely used in cosmetic products due to their antioxidant and anti-inflammatory beneficial properties and their ability to prevent UV radiation-induced oxidative stress. Since these compounds present chromophores and are applied directly to the skin, they can react with sunlight and exert phototoxic effects. The available scientific information on the phototoxic potential of these natural compounds is scarce, and thus the aim of this study was to evaluate the photoreactivity and phototoxicity of five phenolic antioxidants with documented use in cosmetic products. A standard ROS assay was validated and applied to screen the photoreactivity of the natural phenolic antioxidants caffeic acid, ferulic acid, p-coumaric acid, 3,4-dihydroxyphenylacetic acid (DOPAC), and rutin. The phototoxicity potential was determined by using a human keratinocyte cell line (HaCaT), based on the 3T3 Neutral Red Uptake phototoxicity test. Although all studied phenolic antioxidants absorbed UV/Vis radiation in the range of 290 to 700 nm, only DOPAC was able to generate singlet oxygen. The generation of reactive oxygen species is an early-stage chemical reaction as part of the phototoxicity mechanism. Yet, none of the studied compounds decreased the viability of keratinocytes after irradiation, leading to the conclusion that they do not have phototoxic potential. The data obtained with this work suggests that these compounds are safe when incorporated in cosmetic products.     

Nephroprotective Effects of Alhagi camelorum against Cisplatin-Induced Nephrotoxicity in Albino Wistar Rats

Alhagi camelorum (AC) is an old plant with a significant therapeutic value throughout Africa, Asia, and Latin America. The overuse of cisplatin (Cis > 50 mg/m²) is associated with observed nephrotoxicity, ototoxicity, gastrotoxicity, myelosuppression, and allergic reactions. Remedial measures are needed for the protection of nephrotoxicity against cisplatin. Thus, we investigated the nephroprotective effects of AC plant extract to prevent cisplatin-induced nephrotoxicity in albino Wistar rats. The presence of polyphenols, phenolic compounds, tannins, and saponins was revealed during phytochemical investigation, and a significantly intense antioxidant activity was recorded. There were no toxicological symptoms in the treated rats, and no anatomical, physiological, or histological abnormalities were found compared to the control rats. The results of correcting cisplatin-induced nephrotoxicity revealed that the extract has a significant ability to treat kidney damage, with most parameters returning to normal after only three weeks of therapy. It is concluded that co-administration of cisplatin with AC extract showed exceptional nephroprotective effects at a dose of 600 mg/kg for Cis-induced nephrotoxicity.     

Fabrication of Pre-tilted Vertical Alignment Layers for High-Speed Liquid Crystal Display Using Bi-functional Photoreactive Monomers

Abstract

To enable recent 3D and moving picture applications, liquid crystal displays (LCD) must exhibit fast response and wide viewing angle characteristics. Pre-tilted vertical alignment layers for high-speed LCD were fabricated using bi-functional photoreactive monomers. The monomers can be confined to the polyimide layer and photo-polymerized by UV exposure under voltage. Response characteristics of photo-controlled alignment films according to the structure were investigated. Vertical alignment properties were evaluated using a polarizing optical microscope, and electro-optical characteristics were compared through the voltage-transmittance curve and response time measurement. Faster response speed could be obtained by using photoreactive monomers having a long alkyl chain.