An EPR spin probe study of liposomes from sunflower and soybean phospholipids

Comparative properties of lecithin-based liposomes prepared from the mixed phospholipids of sunflower seeds, soybean and egg yolk were investigated by electron paramagnetic resonance (EPR) spectroscopy. For these investigations, stable nitroxide radicals, 1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl 5,7-dimethyladamantane-1-carboxylate (DMAC-TEMPO), 5-doxylstearic acid (5-DSA) and 16-doxylstearic acid (16-DSA) were used as spin probes. Binding of the spin probes to the liposome membranes resulted in a substantial increase of the apparent rotational diffusion correlation times. The EPR spectra of the incorporated nitroxides underwent temperature-dependent changes. For every spin probe, values of apparent enthalpy and entropy of activation were calculated from the temperature dependence of rotational diffusion correlation times via Arrhenius equation. In case of DMAC-TEMPO, the data point to differences between the phospholipid bilayer of liposomes derived from sunflower and soy lecithin, and some similarity between the sunflower and egg yolk liposomes. Anisotropic hyperfine interaction constants of DMAC-TEMPO and 16-DSA included in the liposomes have been analyzed and attributed to different micropolarity of the surroundings of the spin probes. The kinetics of EPR signal decay of DMAC-TEMPO in the presence of 2,2′-azobis(2-amidinopropane) suggest the better stability of the sunflower liposomes to lipid peroxidation as compared to the liposomes prepared from soy lecithin.     

血红细胞超氧化物歧化酶(SOD)制备工艺的研究初报

本文报告了本实验室设计的由血红细胞自溶液60℃热变性, 乙醇——氯仿法除血红蛋白,旋转蒸发法减压浓缩抽去氯仿、乙醇,硫酸铵分级盐析法沉降SOD,Sepbadex G-75层析提纯SOD等步骤构成的一条成本低、设计合理、简便实用的分离纯化SOD的工艺路线。     

Effect of 6-Benzoyl-benzothiazol-2-one scaffold on the pharmacological profile of α-alkoxyphenylpropionic acid derived PPAR agonists

Abstract

A series of nitrogen heterocycles containing α–ethoxyphenylpropionic acid derivatives were designed as dual PPARα/γ agonist ligands for the treatment of type 2 diabetes (T2D) and its complications. 6-Benzoyl-benzothiazol-2-one was the most tolerant of the tested heterocycles in which incorporation of O-methyl oxime ether and trifluoroethoxy group followed by enantiomeric resolution led to the (S)-stereoisomer 44?b displaying the best in vitro pharmacological profile. Compound 44?b acted as a very potent full PPARγ agonist and a weak partial agonist on the PPARα receptor subtype. Compound 44?b showed high efficacy in an ob/ob mice model with significant decreases in serum triglyceride, glucose and insulin levels but mostly with limited body-weight gain and could be considered as a selective PPARγ modulator (SPPARγM).     

Contig assembly of bacterial artificial chromosome clones through multiplexed fluorescence-labeled fingerprinting

A rapid multiplexed fingerprinting method has been developed for bacterial artificial chromosome (BAC) contig assembly. Defined subsets of BAC DNA fragments that result from digestion by three paired restriction endonucleases are labeled with unique fluorescent F-ddATP for each subset. Lists of the labeled fragment size are generated by an ABI 377 DNA sequencer and the GeneScan analysis software and then processed by an assembly program, FPC (Fingerprinted Contigs), to produce contig maps. Data obtained from the multiplexed labeling permit detection of smaller overlaps than is observed when data from a single double-digest are analyzed. The method has been tested on 98 BACs from chromosome 22 regions where large-scale sequencing is under way and also through simulation, using randomly generated BAC clones derived from existing DNA sequence data. In each case, contig assembly results demonstrated the advantages of multiplexed fingerprinting.     

Genome-wide analysis of gene expression during Xenopus tropicalis tadpole tail regeneration

Background

During liver development, intrahepatic bile ducts are thought to arise by a unique asymmetric mode of cholangiocyte tubulogenesis characterized by a series of remodeling stages. Moreover, in liver diseases, cells lining the Canals of Hering can proliferate and generate new hepatic tissue. The aim of this study was to develop protocols for three-dimensional visualization of protein expression, hepatic portal structures and human hepatic cholangiocyte tubulogenesis.

Results

Protocols were developed to digitally visualize portal vessel branching and protein expression of hepatic cell lineage and extracellular matrix deposition markers in three dimensions. Samples from human prenatal livers ranging from 7 weeks + 2 days to 15½ weeks post conception as well as adult normal and acetaminophen intoxicated liver were used. The markers included cytokeratins (CK) 7 and 19, the epithelial cell adhesion molecule (EpCAM), hepatocyte paraffin 1 (HepPar1), sex determining region Y (SRY)-box 9 (SOX9), laminin, nestin, and aquaporin 1 (AQP1). Digital three-dimensional reconstructions using CK19 as a single marker protein disclosed a fine network of CK19 positive cells in the biliary tree in normal liver and in the extensive ductular reactions originating from intrahepatic bile ducts and branching into the parenchyma of the acetaminophen intoxicated liver. In the developing human liver, three-dimensional reconstructions using multiple marker proteins confirmed that the human intrahepatic biliary tree forms through several developmental stages involving an initial transition of primitive hepatocytes into cholangiocytes shaping the ductal plate followed by a process of maturation and remodeling where the intrahepatic biliary tree develops through an asymmetrical form of cholangiocyte tubulogenesis.

Conclusions

The developed protocols provide a novel and sophisticated three-dimensional visualization of vessels and protein expression in human liver during development and disease.     

Electrical detection of human immunoglobulins G from human serum using a microbiosensor

A biosensor for the electrical detection of human antibodies from serum has been fabricated and experimentally demonstrated. The device is based on the immobilization of proteins used as probes between a set of microelectrodes. Incubation with diluted human serum was followed by incubation with anti-human secondary antibodies labeled with gold nanoparticles (GNPs) and then precipitation of silver on the nanoparticles. The output of the device was defined as the percentage of short-circuited microelectrodes after silver deposition independently of the gap conductance. Two model probes were studied: protein A and goat antibodies. The effects of the microgap spacing (5, 10, 15 or 20 microm) and the duration of the silver treatment were examined. The data obtained showed that a large spacing (20 microm) led to poor sensitivity. Alternately, 5 microm gaps led to high sensitivity and saturation of the signal. Interestingly, 10-15 microm gaps enabled a non-saturated and distinct signal for both probes that was correlated with the GNP density between the microgaps as determined by atomic force microscopy. Different capture efficiencies could be easily distinguished. The biosensor described here is easy to use and thus can be applied to real detection experiments.     

Transcriptional profiling of bovine intervertebral disc cells: implications for identification of normal and degenerate human intervertebral disc cell phenotypes

Introduction  

Nucleus pulposus (NP) cells have a phenotype similar to articular cartilage (AC) cells. However, the matrix of the NP is clearly different to that of AC suggesting that specific cell phenotypes exist. The aim of this study was to identify novel genes that could be used to distinguish bovine NP cells from AC and annulus fibrosus (AF) cells, and to further determine their expression in normal and degenerate human intervertebral disc (IVD) cells.     

Characterization of nanogap chemical reactivity using peptide-capped gold nanoparticles and electrical detection

Nanogaps are usually combined with synthetic or biological molecules to produce nanodevices having novel properties. This combination is better realized by controlling the chemical properties of the nanogap. We show here that the presence of a specific chemical group inside nanogaps (30-90 nm) can be probed electrically using 10 nm gold nanoparticles derivatized by complementary functional groups. 100-10(4)-fold current increases were observed following the site-specific insertion of gold nanoparticles into the nanogap.