Evaluation of Gene Expression Knock-Down by Chemically and Structurally Modified Gapmer Antisense Oligonucleotides

We analyzed the effect of modified nucleotides within gapmer antisense oligonucleotides on RNase H mediated gene silencing. Additionally, short hairpins were introduced into antisense oligonucleotides as structural motifs, and their influence on biological and physicochemical properties of pre-structured gapmers was investigated for the first time. The results indicate that two LNA residues in specified positions of the gap flanking regions are sufficient and favorable for efficient knock-down of the β-actin gene. Furthermore, the introduction of other modified nucleotides, i. e. glycyl-amino-LNA−T, 2′-O-propagyluridine, polyamine functionalized uridine, and UNA, in specified positions, also increases the inhibition of β-actin expression. Importantly, the presence of hairpins within the gapmers improves their silencing properties.     

Mechanism and kinetics of the free radical ring-opening polymerization of cyclic allylic sulfide lactones

The polymerization of 7-, 8- and 11-membered lactones, 6-methylene-1,4-oxathiepan-7-one, 3-methylene-1,5-oxathiocan-2-one and 3-methylene-1-oxa-5-thiacycloundecan-2-one in benzene at 70, 40–70 and 40–65 °C, respectively, is presented. All polymerizations proceeded with complete ring-opening up to approximately 25% conversion, where insoluble polymer was formed. Evidence is given attributing polymer double bond loss to crosslinking, although redistribution of the molecular weights via addition to polymer double bonds followed by β-fragmentation also appears to occur for polymerizations of the 8- and 11-membered lactones. Michael adducts of lactones with 2-methyl-2-propanethiol were prepared as models for chain-transfer products of hydrogen abstraction by carbon-centred radicals. Polymerization rates were found to increase marginally with ring size. Arrhenius parameters obtained for the polymerizations of the 8- and 11-membered lactones indicated that the addition step was more important than fragmentation in determining the rate of propagation.     

Antifeedants against <Emphasis Type="Italic">Hylobius abietis</Emphasis> Pine Weevils: An Active Compound In Extract of Bark of <Emphasis Type="Italic">Tilia cordata</Emphasis> Linden

Linden (Tilia cordata) bark was shown to contain an antifeedant effective against the large pine weevil, Hylobius abietis. Soxhlet extraction of inner and outer bark resulted in an extract that showed antifeedant activity in a microfeeding assay. The extract was fractionated by chromatography on silica gel using gradient elution with solvents of increasing polarity. The content of the fractions obtained was monitored by thin layer- and gas chromatography. Fractions of similar chemical composition were merged. Two of the 17 fractions showed antifeedant activity in the microfeeding assay. Nonanoic acid was identified in both of these fractions. Subsequent testing in the microfeeding assay showed that nonanoic acid possessed strong antifeedant activity against H. abietis adults.     

Profiles of the concentrations of components along the column height at different liquid holdup distributions in distillation of binary and ternary mixtures

The distribution of components along the distillation column height in distillation of binary and ternary mixtures is studied at different profiles of liquid holdup in the system. It is shown that physical modeling of continuous and batch distillation at infinite reflux ratio without taking into account the liquid holdup distribution may be inadequate to the real process. Equations for the curvilinear equilibrium line are proposed, which relate the number of transfer units, the number of theoretical separation stages, and the component concentration.Translated from Teoreticheskie Osnovy Khimicheskoi Tekhnologii, Vol. 39, No. 1, 2005, pp. 3–6.Original Russian Text Copyright © 2005 by Lotkhov, Dilman, Lipatova, Kvashnin, Kulov.     

Fast internal dynamics in polyelectrolyte gels measured by dynamic light scattering

Summary Dynamic light scattering was used to investigate the dynamics of sodium poly(styrene sulfonate) and fully neutralized poly(acrylic acid) gels as a function of the degree of swelling and weight ratio of cross-linking agent. It was shown that the collective diffusion coefficient increases with increasing degree of swelling and that the diffusion coefficient shows stronger concentration dependence than predicted by scaling arguments. For gel samples measured at the swelling equilibrium, the diffusion coefficient increases with increasing gel concentration for both gel systems.     

Phase transformations in face centered cubic (Al0.32Cr0.68)2O3 thin films

Face centered cubic (Al_0.32Cr_0.68)₂O₃ thin films have been annealed in the temperature range of 500–1000 °C during 2–8 h. The fcc structure of the film remains intact when annealed at temperatures up to 700 °C for 8 h. X-ray diffraction and transmission electron microscopy show the onset of phase transformation to corundum phase alloys in the sample annealed at 900 °C for 2 h, where annealing at 1000 °C for 2 h results in complete phase transformation to α-(Al_0.32Cr_0.68)₂O₃. In-plane and out-of-plane line scans performed in EDX TEM and θ/2θ XRD patterns did not show any phase separation into α-Cr₂O₃ and Al₂O₃ prior and after the annealing. The apparent activation energy of this process is 380–480 kJ/mol as determined by the Johnson–Mehl–Avrami model.     

Preparation of thermoset composites from natural fibres and acrylate modified soybean oil resins

Structural composites with a high content of renewable material were produced from natural fibres and an acrylated epoxidized soybean oil resin. Composites were prepared by spray impregnation followed by compression moulding at elevated temperature. The resulting composites had good mechanical properties in terms of tensile strength and flexural strength. Tensile testing as well as dynamical mechanical thermal analysis showed that increasing the fibre content, increased the mechanical properties. The resin can be reinforced with up to 70 wt % fibre without sacrifice in processability. The tensile modulus ranged between 5.8 and 9.7 GPa depending on the type of fibre mat. The study of the adhesion by low vacuum scanning electron microscopy shows that the fibres are well impregnated in the matrix. The aging properties were finally evaluated. This study shows that composites with a very high content of renewable constituents can be produced from soy bean oil resins and natural fibres. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Observing Proteins as Single Molecules Encapsulated in Surface‐Tethered Polymeric Nanocontainers

Protein unfolding inside immobilized polymerosomes : One of the most interesting properties of polymeric vesicles is their remarkable stability against extreme temperatures and osmotic stress, and their longevity even under harsh environmental conditions. We have demonstrated, in an application on protein folding, that surface‐tethered polymerosomes are suitable for performing time‐resolved single molecule studies with encapsulated proteins, as illustrated here.

     

Double Mutant Cycles as a Tool to Address Folding,Binding, and Allostery

Quantitative measurement of intramolecular and intermolecular interactions in protein structure is an elusive task, not easy to address experimentally. The phenomenon denoted ‘energetic coupling’ describes short- and long-range interactions between two residues in a protein system. A powerful method to identify and quantitatively characterize long-range interactions and allosteric networks in proteins or protein–ligand complexes is called double-mutant cycles analysis. In this review we describe the thermodynamic principles and basic equations that underlie the double mutant cycle methodology, its fields of application and latest employments, and caveats and pitfalls that the experimentalists must consider. In particular, we show how double mutant cycles can be a powerful tool to investigate allosteric mechanisms in protein binding reactions as well as elusive states in protein folding pathways.