Lipid complexes with cationic peptides and OAKs; their role in antimicrobial action and in the delivery of antimicrobial agents

Antimicrobial agents are toxic to bacteria by a variety of mechanisms. One mechanism that is very dependent on the lipid composition of the bacterial membrane is the clustering of anionic lipid by cationic antimicrobial agents. Certain species of oligo-acyl-lysine (OAK) antimicrobial agents are particularly effective in clustering anionic lipids in mixtures mimicking the composition of bacterial membranes. The clustering of anionic lipids by certain cationic antimicrobial agents contributes to the anti-bacterial action of these agents. Bacterial membrane lipids are a determining factor, resulting in some species of bacteria being more susceptible than others. In addition, lipids can be used to increase the effectiveness of antimicrobial agents when administered in vivo. Therefore, we review some of the structures in which lipid mixtures can assemble, to more effectively be utilized as antimicrobial delivery systems. We describe in more detail the complexes formed between mixtures of lipids mimicking bacterial membranes and an OAK and their usefulness in synergizing with antibiotics to overcome bacterial multidrug resistance.     

Highly reactive oxygen species: detection, formation, and possible functions

The so-called reactive oxygen species (ROS) are defined as oxygen-containing species that are more reactive than O(2) itself, which include hydrogen peroxide and superoxide. Although these are quite stable, they may be converted in the presence of transition metal ions, such as Fe(II), to the highly reactive oxygen species (hROS). hROS may exist as free hydroxyl radicals (HO·), as bound ("crypto") radicals or as Fe(IV)-oxo (ferryl) species and the somewhat less reactive, non-radical species, singlet oxygen. This review outlines the processes by which hROS may be formed, their damaging potential, and the evidence that they might have signaling functions. Since our understanding of the formation and actions of hROS depends on reliable procedures for their detection, particular attention is given to procedures for hROS detection and quantitation and their applicability to in vivo studies.     

Our impasse in developing a malaria vaccine

Malaria presents a challenge to world health that to date has been beyond the abilities of researchers to conquer. This critique presents some of the strategies employed by the parasite to overcome immunity and the immunological challenges that we face to develop vaccines. A conclusion is that a vaccine must identify novel antigens or epitopes that are not normally immunogenic and which are therefore not under immune pressure and most likely to be conserved between different strains. Such antigens are most likely to be targets of cellular immunity. The case for a whole parasite blood stage vaccine is presented based on these premises.     

Effects of Hydrophilic Monomer Types and Level on Polystyrene-Acrylate/montmorillonite Nanocomposite Made by Emulsion Polymerization

1 Results Nanocomposite has attracted more and more interest all over the world.Polystyrene (PS) is a commercialized and mass-productive polymer,continuous research efforts have been devoted to the development of polystyrene/montmorillonite (PS/MMT) nanocomposites[1-2].But the polarity of styrene (St) is too small to intercalate the space between the clay layers.The polarity of hydrophilic monomer is so strong that it can intercalate the MMT easily,the intercalated smectic clays maybe exfoliated by usin...     

混凝土板梁的有限条法简化分析

桥梁结构在各种荷载作用下产生的内力和弯矩影响着桥梁的性能.桥梁弯曲、扭转和挠度等过大时会导致结构的破坏,这在结构设计阶段就应加以分析.本文提出一种有限条简化分析方法,可以较好地分析桥梁的挠度、弯曲和扭转变形.通过对一座简支板梁桥模型的分析,与现行有限元方法的分析结果进行了比较.结果表明,本方法能够较好地处理边界条件,只需要很少的输入工作就可以得到正确的分析结果,从而为结构工程师提供了一种用于分析板梁桥在交通荷载作用下行为的有效工具.     

Gene polymorphism in Netherton and common atopic disease.

Atopic dermatitis (AD) and asthma are characterized by IgE-mediated atopic (allergic) responses to common proteins (allergens), many of which are proteinases. Loci influencing atopy have been localized to a number of chromosomal regions, including the chromosome 5q31 cytokine cluster. Netherton disease is a rare recessive skin disorder in which atopy is a universal accompaniment. The gene underlying Netherton disease (SPINK5) encodes a 15-domain serine proteinase inhibitor (LEKTI) which is expressed in epithelial and mucosal surfaces and in the thymus. We have identified six coding polymorphisms in SPINK5 (Table 1) and found that a Glu420-->Lys variant shows significant association with atopy and AD in two independent panels of families. Our results implicate a previously unrecognized pathway for the development of common allergic illnesses.     

The nuclear envelope: emerging roles in development and disease

The chromosomes of eukaryotic cells are separated from the cytoplasm by the nuclear envelope. The nuclear envelope includes two riveted membranes, plus embedded pore complexes that mediate nuclear import and export. In this sense, the nuclear envelope is truly a border zone. However, the envelope also links directly to chromosomes, and anchors two major infrastructures--the nuclear lamina and Tpr filaments--to the nuclear perimeter. Proteins of the nuclear envelope mediate a variety of fundamental activities, including DNA replication, gene expression and silencing, chromatin organization, cell division, apoptosis, sperm nuclear remodeling, the behavior of pronuclei, cell fate determination, nuclear migration and cell polarity. Furthermore, mutations in nuclear lamins and lamin-binding proteins cause tissue-specific inherited diseases. This special issue of Cell and Molecular Life Sciences is devoted to recent major advances in the characterization of nuclear envelope proteins and their roles. We offer here an overview of the topics covered in this issue of CMLS, and also discuss the emerging recognition that the nuclear envelope is an organelle critical for a wide range of genetic and developmental activity in multicellular organisms.     

Influence of prey movement on the aim of predatory strikes of the western rattlesnake ( Crotalus Viridis )

The purpose of this study was to determine whether the western rattlesnake ( Crotalus viridis ) aims its predatory strike at the head/thorax region of mice primarily on the basis of cues related to the direction of prey movement. We hypothesized that when rattlesnakes strike at anesthetized, backward-moving mice, most strikes would be aimed at the forward-most-moving region, i.e., the posterior (abdomen/tail) region of prey. However, most mice were struck in the anterior (head/thorax) region, implying that the visual-infrared image of mice, rather than directional movement, guides the aim of predatory strikes.