Chitosan–Quercetin Bioconjugate as Multi‐Functional Component of Antioxidants and Dual‐Responsive Hydrogel Networks

Multifunctional hydrogels based on chitosan–quercetin (CHITQ) conjugate are prepared by a thermo‐induced radical procedure in the presence of N‐isopropylacrylamide (NIPAAm), acrylamide (AAm), and N,N′‐methylenebis(acrylamide) (MEBA). At first, quercetin (Q) is grafted onto chitosan backbone with a functionalization degree of 275 mg of Q per gram of conjugate, as calculated by ¹H‐NMR analyses to impart antioxidant properties to the polysaccharide. Then, a pH and temperature sensitive hydrogel was obtained by involving CHITQ and NIPAAm in the polymerization reaction. The accessibility of phenolic moieties is modified in response to the hydrogel swelling/deswelling, as confirmed by antioxidant tests performed at different temperatures. Dual stimuli‐responsive hydrogels are proposed for the delivery of caffeine as model drug. The release profiles of caffeine depict a system particularly performing as on/off device at acidic pH with excellent applicability prospects.     

Early behavioral associations of achievement trajectories.

Duncan et al. (2007) examined associations between early behavioral and cognitive skills with later achievement. These associations were examined in 6 different data sets and results converged to suggest that early behavioral competences or problems had little, if any, prediction to later achievement and that attentional competences had small positive relations with later achievement. In contrast, cognitive abilities were by far the strongest predictors of achievement. We provide and investigate potential reasons why Duncan et al. found little to no association between behavior and later achievement in a reanalysis of data from 3 studies previously analyzed by Duncan et al. Potential reasons include the validity of the behavioral measures, treatment of the behavioral measures as continuous as opposed to categorical, and the choice of data analytic method. In this article, we discuss these issues at greater length and address them in our reanalysis. We also bring into question the nature of the relationship between behavior and achievement. Generally, our reanalysis supports the idea that attention measures are more predictive than behavioral measures; however, certain behavior measures showed small to moderate associations to concurrent levels of academic achievement and changes in academic achievement through elementary school. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Performance Evaluation of the Standard Proway Network for Process Control

A sort of informal and formal standardization process is now under development so as to obtain ``standard' technologies which can be efficiently used for the networking of given distributed applications. An example of this trend in the Proway architecture that is developed by the International Electrotechnical Commission (IEC) to obtain a Local Area Network (LAN) for industrial process control. The aim of this paper is to present a performance evaluation of the Proway network by using a simulation approach. By this we determine the field of applicability of such a standard to obtain a distributed system for process control. The paper shows not only the service quality offered by the Proway, but also an automated method to study the performances of a wide class of distributed systems. The results show that low service time and high throughput are not consistent, so that, during the design of the network, it is necessary to choose what feature is more important for the considered application. A simulator is a powerful tool that can help the designer to choose the best compromise among various parameters and might be used to obtain the parameter variability range which provides the expected performances.     

Copper: An Intracellular Achilles’ Heel Allowing the Targeting of Epigenetics,Kinase Pathways,and Cell Metabolism in Cancer Therapeutics

Copper is an essential transition metal frequently increased in cancer known to strongly influence essential cellular processes. Targeted therapy protocols utilizing both novel and repurposed drug agents initially demonstrate strong efficacy, before failing in advanced cancers as drug resistance develops and relapse occurs. Overcoming this limitation involves the development of strategies and protocols aimed at a wider targeting of the underlying molecular changes. Receptor Tyrosine Kinase signaling pathways, epigenetic mechanisms and cell metabolism are among the most common therapeutic targets, with molecular investigations increasingly demonstrating the strong influence each mechanism exerts on the others. Interestingly, all these mechanisms can be influenced by intracellular copper. We propose that copper chelating agents, already in clinical trial for multiple cancers, may simultaneously target these mechanisms across a wide variety of cancers, serving as an excellent candidate for targeted combination therapy. This review summarizes the known links between these mechanisms, copper, and copper chelation therapy.     

Design,Synthesis, and Biological Evaluation of Tetrahydro‐β‐carboline Derivatives as Selective Sub‐Nanomolar Gelatinase Inhibitors

Targeting matrix metalloproteinases (MMPs) is a pursued strategy for treating several pathological conditions, such as multiple sclerosis and cancer. Herein, a series of novel tetrahydro‐β‐carboline derivatives with outstanding inhibitory activity toward MMPs are present. In particular, compounds 9 f , 9 g , 9 h and 9 i show sub‐nanomolar IC₅₀ values. Interestingly, compounds 9 g and 9 i also provide remarkable selectivity toward gelatinases; IC₅₀=0.15 nm for both toward MMP‐2 and IC₅₀=0.63 and 0.58 nm , respectively, toward MMP‐9. Molecular docking simulations, performed by employing quantum mechanics based partial charges, shed light on the rationale behind binding involving specific interactions with key residues of S1′ and S3′ domains. Taken together, these studies indicate that tetrahydro‐β‐carboline represents a promising scaffold for the design of novel inhibitors able to target MMPs and selectively bias gelatinases, over the desirable range of the pharmacokinetics spectrum.     

Influence of the Salt Concentration on the Properties of Salt‐Free Polyelectrolyte Complex Membranes

Polyelectrolyte complexes (PECs) prepared by solution mixing of cationic poly(diallyldimethylammonium chloride) and anionic poly(sodium 4‐styrene sulfonate) with various NaCl content are processed into films. Salt‐free (SF‐PEC) membranes are produced by rinsing the PEC in water overnight. The main finding of this paper is that SF‐PEC films have different properties depending on the NaCl concentration used during the processing step. Dynamic mechanical analysis measurement confirms that hydrated SF‐PEC film processed from higher salt content has a higher modulus than when processed without salt and the glass transition temperature appears to shift to higher values. Processing the PECs films in the presence of salt also has an interesting effect on their shape memory characteristics. SF‐PEC films prepared with high‐salt concentration are shown to maintain a programmed temporary shape better than materials prepared with low salt, while recovery is possible within a short period of time when immersed in hot water.     

Use of the Semipermeable Membrane Device (Spmd) to Sample Polycyclic Aromatic Hydrocarbon Pollution In A Lotic System

Abstract

Relative concentrations of aqueous polycyclic aromatic hydrocarbons (PAH) were investigated in an urban creek. Samples were obtained at five sites within a 600-m segment of the creek that is critical habitat for an endangered species of fish. the sampling technique entailed immersion of semipermeable membrane devices (SPMDs) in the water for intervals as long as 64 d. SPMDs are passive, in situ, mtegrative samplers of bioavailable (truly dissolved) PAH and other hydrophobic organic contaminants. Two point sources of PAH to the 600-m segment of the creek were differentiated. Aqueous concentrations were found to wane dramatically over the relatively short section of the creek between the point sources. All samples were almost devoid of alkyl-substituted PAH, indicating that the ultimate sources were probably of pyrogenic nature.