Synthesis and anticancer properties of RGD peptides conjugated to nitric oxide releasing functional groups and abiraterone

A series of analogues of the integrin binding aspartic acid-glycine-arginine (RGD) peptide sequence were synthesised conjugated to nitric oxide (NO) donating functional groups. Also the cytotoxicity of abiraterone, a prostate cancer drug, was explored when it was conjugated in three part constructs to RGD sequences and NO releasing heterocycles. In general the analogues showed integrin binding affinity comparable to RGD reference compounds, and all released NO by the Griess test assay. Two analogues exhibited significant cytotoxic effects against PC3 and MCF7 cell lines.     

Enhanced coding for exponentially distributed signals using suprathreshold stochastic resonance

Our previous work on stochastic resonance (SR) in threshold based systems proved that the SR effect is dependent on the nature of the input signal distribution; more specifically, for certain types of signal distribution SR is not observed [Das A, Stocks NG, Nikitin A, Hines EL. Quantifying stochastic resonance in a single threshold detector for random aperiodic signals. Fluctuation Noise Lett 2004;4:L247–65]. Here we show that suprathreshold stochastic resonance (SSR) – a novel and distinct form of SR – removes this limitation and hence leads to the conclusion that SSR can probably enhance the transmission of signals of any distribution and amplitude. SSR effects are studied in a parallel array of identical nonlinear threshold based devices. A double exponential signal distribution is chosen because this distribution did not demonstrate conventional SR effects in a single threshold device [Das A, Stocks NG, Nikitin A., Hines EL. Quantifying Stochastic resonance in a single threshold detector for random aperiodic signals. Fluctuation and Noise Letters 2004;4:L247-L265.]. SSR as a possible mechanism for enhancing transmission of speech signals in the human ear is also discussed.     

Microwave-Assisted Direct Synthesis of 4H-1,2,4-Benzothiadiazine 1,1-Dioxide Derivatives

Abstract

We describe a rapid and convenient methodology for the preparation of diverse 3-aryl and 3-trifluoromethyl 4H-1,2,4-benzothiadiazine-1,1-dioxides in a one-pot microwave-promoted reaction between 2-aminobenzenesulfonamides and benzaldehydes, trifluoroacetic acid or benzoic acids.

GRAPHICAL ABSTRACT      

Preparation and characterization of octadecyl acrylate monoliths for capillary electrochromatography by photochemical,thermal, and chemical initiation†

Monolithic stationary phases based on octadecyl acrylate for CEC using different initiating systems (UV irradiation, thermal, and chemical initiation) in the presence of lauroyl peroxide as initiator were synthesized. For each initiation mode, the influence of the porogenic solvent composition on both the morphological and electrochromatographic properties of the resulting monoliths was investigated. Under optimal conditions, excellent efficiencies for the photochemically and chemically polymerized monoliths (minimum plate heights of 6.9–10.7 and 6.5–12.6 μm, respectively) were achieved. Thermally initiated columns gave lower efficiency values, permeabilities, and longer analysis times compared to these initiating systems. The produced monolithic stationary phases were evaluated in terms of reproducibility and gave RSD values below 9.2, 10.6, and 9.8% for UV, thermally, and chemically initiated columns, respectively.     

Determination of the elastic constants of nematic liquid crystals by means of the affine transformation model

In this paper the affine connection approach will be used to calculate the elastic constants of nematic liquid crystals. Following this approach, which was originally conceived to compute the nematic viscosity coefficients, an expression for the elastic constants, without adjustable free parameters, will be formulated in terms of a temperature dependent metric, whose non‐isotropic part is proportional to the tensorial order parameter of the nematic phase. The dependence of the elastic constants on the scalar order parameter, in the geometry of the nematic molecules, and in the anisotropic part of the molecular interaction, will be determined.     

Simultaneous Determination of Hydrogen Peroxide and Organic Hydroperoxides in Water

The kinetics of the reactions of H 2 O 2 and of methyl, ethyl, tert -butyl, and cumene hydroperoxides with I m were investigated in the presence and absence of molybdate as catalyst. These results were utilized to develop an analytical method for the simultaneous determination of H 2 O 2 and organic hydroperoxides in aqueous solutions. The total amount of H 2 O 2 and organic hydroperoxides can be determined by the spectrophotometric measurement of $ {\rm I}_3^ - $ formed quantitatively during 30 min of heating at 60°C. Catalase selectively decomposes H 2 O 2 in solutions containing organic hydroperoxides. The total amount of the latter can therefore be determined iodometrically after H 2 O 2 decomposition. In the oxidation of leuco crystal violet to crystal violet by H 2 O 2 and organic hydroperoxides, horseradish peroxidase exerts similar activities in the reactions involving methyl and ethyl hydroperoxides and H 2 O 2 , but its activity is much lower with tert -butyl and cumene hydroperoxide. It was observed that acetate buffer is unsuitable for pH adjustment in this type of hydroperoxide determination in consequence of the slow oxidation of the dye in the blank solution.