康惠尔水胶体透明贴对阿奇霉素引起的静脉炎的预防作用

目的:观察康惠尔水胶体透明贴对使用阿奇霉素引起的静脉炎的疗效与效果。方法:从我院2009年1月-2010年1月的呼吸内科患者中选择100例使用阿奇霉素静脉输液治疗的患者。分为观察组与对照组,每组50名使用阿奇霉素静脉输液治疗的患者。普通组使用普通透明贴,对照组患者使用康惠尔水胶体透明贴。对两组患者进行比对。结果:观察组的50名患者使用普通透明贴,16例未发生静脉炎,发生静脉炎为34例;对照组的50名患者使用康惠尔水胶体透明贴,仅有2例发生静脉炎的患者。对照组与普通组相比,对照组结果好于普通组,P<0.05差距有显著统计学意义。结论:使用康惠尔水胶体透明贴可以有效的减少呼吸内科患者使用阿奇霉素造成的静脉炎发生率。     

Showing your ID: intrinsic disorder as an ID for recognition, regulation and cell signaling

Regulation, recognition and cell signaling involve the coordinated actions of many players. To achieve this coordination, each participant must have a valid identification (ID) that is easily recognized by the others. For proteins, these IDs are often within intrinsically disordered (also ID) regions. The functions of a set of well-characterized ID regions from a diversity of proteins are presented herein to support this view. These examples include both more recently described signaling proteins, such as p53, alpha-synuclein, HMGA, the Rieske protein, estrogen receptor alpha, chaperones, GCN4, Arf, Hdm2, FlgM, measles virus nucleoprotein, RNase E, glycogen synthase kinase 3beta, p21(Waf1/Cip1/Sdi1), caldesmon, calmodulin, BRCA1 and several other intriguing proteins, as well as historical prototypes for signaling, regulation, control and molecular recognition, such as the lac repressor, the voltage gated potassium channel, RNA polymerase and the S15 peptide associating with the RNA polymerase S-protein. The frequent occurrence and the common use of ID regions in important protein functions raise the possibility that the relationship between amino acid sequence, disordered ensemble and function might be the dominant paradigm for the molecular recognition that serves as the basis for signaling and regulation by protein molecules.     

Microbead-based electrochemical immunoassay with interdigitated array electrodes

The objective of this study was to develop a sensitive and miniaturized immunoassay by coupling a microbead-based immunoassay with an interdigitated array (IDA) electrode. An IDA electrode amplifies the signal by recycling an electrochemically redox-reversible molecule. The microfabricated platinum electrodes had 25 pairs of electrodes with 1.6-microm gaps and 2.4-microm widths. An enzyme-labeled sandwich immunoassay on paramagnetic microbeads with mouse IgG as the analyte and beta-galactosidase as the enzyme label was used as the model system. beta-Galactosidase converted p-aminophenyl beta-D-galactopyranoside to p-aminophenol (PAP). This enzyme reaction was measured continuously by positioning the microbeads near the electrode surface with a magnet. Electrochemical recycling occurred with PAP oxidation to p-quinone imine (PQI) at +290 mV followed by PQI reduction to PAP at -300 mV vs Ag/AgCl. Dual-electrode detection amplified the signal fourfold compared to single-electrode detection, and the recycling efficiency reached 87%. A calibration curve of PAP concentration vs anodic current was linear between 10(-4) and 10(-6)M. A signal from 1000 beads in a 20-microL drop was detectable and the immunoassay was complete within 10 min with a detection limit of 3.5x10(-15)mol mouse IgG.     

Carbon nanotube aqueous sol-gel composites: enzyme-friendly platforms for the development of stable biosensors

A new type of composite material based on carbon nanotubes and an aqueous sol-gel process has been developed. The electrochemical characteristics of these composites were investigated and compared to composites made with an alkoxy silane sol-gel process. The use of carbon nanotubes, as the conductive part of the composite, facilitated fast electron transfer rates. The feasibility of this type of composite for the development of biosensors was demonstrated using l-amino acid oxidase. The stability of the enzyme was increased when it was encapsulated in the aqueous sol-gel, and the sensor retained more that 50% of its response after 1 month of testing.     

Selective placement of templated DNA nanowires between microstructured electrodes

Dip-pen nanolithography is used to selectively modify the SiOx area between microfabricated electrodes. The modified surface is characterized by atomic force microscopy, X-ray photoelectron spectroscopy, force volume imaging, and adhesion maps. The functionalized complex architecture is used for the localization of DNA coated with magnetic nanoparticles. The strategy reported here can become the basis for the construction of a number of functional devices. The devices can utilize the unique recognition properties of the DNA and the magnetic properties of the nanoparticles that template them.     

A model for co-translational translocation: ribosome-regulated nascent polypeptide translocation at the protein-conducting channel

The protein-conducting channel (PCC) must allow both the translocation of soluble polypeptide regions across, and the lateral partitioning of hydrophobic transmembrane helices (TMHs) into, the membrane. We have analyzed existing structures of ribosomes and ribosome-PCC complexes and observe conformational changes suggesting that the ribosome may sense and orient the nascent polypeptide and also facilitate conformational changes in the PCC, subsequently directing the nascent polypeptide into the appropriate PCC-mediated translocation mode. The PCC is predicted to be able to accommodate one central, consolidated channel or two segregated pores with different lipid accessibilities, which may enable the lipid-mediated partitioning of a TMH from one pore, while the other, aqueous, pore allows translocation of a hydrophilic polypeptide segment. Our hypothesis suggests a plausible mechanism for the transitioning of the PCC between different configurations.     

Fast and accurate modeling of protein-protein interactions by combining template-interface-based docking with flexible refinement

The similarity between folding and binding led us to posit the concept that the number of protein-protein interface motifs in nature is limited, and interacting protein pairs can use similar interface architectures repeatedly, even if their global folds completely vary. Thus, known protein-protein interface architectures can be used to model the complexes between two target proteins on the proteome scale, even if their global structures differ. This powerful concept is combined with a flexible refinement and global energy assessment tool. The accuracy of the method is highly dependent on the structural diversity of the interface architectures in the template dataset. Here, we validate this knowledge-based combinatorial method on the Docking Benchmark and show that it efficiently finds high-quality models for benchmark complexes and their binding regions even in the absence of template interfaces having sequence similarity to the targets. Compared to "classical" docking, it is computationally faster; as the number of target proteins increases, the difference becomes more dramatic. Further, it is able to distinguish binders from nonbinders. These features allow performing large-scale network modeling. The results on an independent target set (proteins in the p53 molecular interaction map) show that current method can be used to predict whether a given protein pair interacts. Overall, while constrained by the diversity of the template set, this approach efficiently produces high-quality models of protein-protein complexes. We expect that with the growing number of known interface architectures, this type of knowledge-based methods will be increasingly used by the broad proteomics community.     

Preparation and characterization of EGCase I, applicable to the comprehensive analysis of GSLs, using a rhodococcal expression system

Endoglycoceramidase (EGCase) is a glycosidase capable of hydrolyzing the β -glycosidic linkage between the oligosaccharides and ceramides of glycosphingolipids (GSLs). Three molecular species of EGCase differing in specificity were found in the culture fluid of Rhodococcus equi (formerly Rhodococcus sp. M-750) and designated EGCase I, II, and III. This study describes the molecular cloning of EGCase I and characterization of the recombinant enzyme, which was highly expressed in a rhodococcal expression system using Rhodococcus erythropolis. Kinetic analysis revealed the turnover number (k(cat)) (k(cat)) of the recombinant EGCase I to be 22- and 1,200-fold higher than that of EGCase II toward GM1a and Gb3Cer, respectively, although the K(m) of both enzymes was almost the same for these substrates. Comparison of the three-dimensional structure of EGCase I (model) and EGCase II (crystal) indicated that a flexible loop hangs over the catalytic cleft of EGCase II but not EGCase I. Deletion of the loop from EGCase II increased the k(cat) of the mutant enzyme, suggesting that the loop is a critical factor affecting the turnover of substrates and products in the catalytic region. Recombinant EGCase I exhibited broad specificity and good reaction efficiency compared with EGCase II, making EGCase I well-suited to a comprehensive analysis of GSLs.     

Simulations of the p97 complex suggest novel conformational states of hydrolysis intermediates

The vitally important AAA (ATPases associated with various cellular activities) protein p97 is involved in cellular functions ranging from replication to degradation of misfolded proteins and has recently been proposed as a novel chemotherapeutic target. p97 is a large molecular machine that has been shown to hexamerize in vitro, with each monomer consisting of an N domain responsible for binding to effector proteins and two AAA repeats (D1 and D2). However, structural studies are inconclusive or in disagreement with one another on several important features such as the locations of the N domains, the relative orientations of the D1 and D2 rings, and the dimensions of the central pore. Here, we present atomic-scale simulations of the p97 hexamer in the prehydrolysis, transition, and post-hydrolysis states. To improve the agreement between low- and high-resolution experimental studies, we first use a biased simulation technique, molecular dynamics flexible fitting (MDFF), to improve the correlation between the structures described in these experiments. We follow this with extended, classical molecular dynamics simulations, which not only show that structures generated in the MDFF phase are stable, but reveal insights into the dynamics important to each state. Simulation results suggest a hybrid model for hydrolysis, in which the N and D2 domains are dynamic while the D1 domains are relatively static, salt bridges stabilize the position of the N domains in the pre-hydrolysis state, and the rings formed by D1 and D2 rotate relative to one another.