Rationally Designed Polypharmacology: α-Helix Mimetics as Dual Inhibitors of the Oncoproteins Mcl-1 and HDM2

Protein–protein interactions (PPIs), many of which are dominated by α-helical recognition domains, play key roles in many essential cellular processes, and the dysregulation of these interactions can cause detrimental effects. For instance, aberrant PPIs involving the Bcl-2 protein family can lead to several diseases including cancer, neurodegenerative diseases, and diabetes. Interactions between Bcl-2 pro-life proteins, such as Mcl-1, and pro-death proteins, such as Bim, regulate the intrinsic pathway of apoptosis. p53, a tumor-suppressor protein, also has a pivotal role in apoptosis and is negatively regulated by its E3 ubiquitin ligase HDM2. Both Mcl-1 and HDM2 are upregulated in numerous cancers, and, interestingly, there is crosstalk between both protein pathways. Recently, synergy has been observed between Mcl-1 and HDM2 inhibitors. Towards the development of new anticancer drugs, we herein describe a polypharmacology approach for the dual inhibition of Mcl-1 and HDM2 by employing three densely functionalized isoxazoles, pyrazoles, and thiazoles as mimetics of key α-helical domains of their partner proteins.     

Influence of size-classified and slightly soluble mineral additives on hydration of tricalcium silicate

Early-age hydration of cement is enhanced by slightly soluble mineral additives (ie, fillers, such as quartz and limestone). However, few studies have attempted to systematically compare the effects of different fillers on cementitious hydration rates, and none have quantified such effects using fillers with comparable, size-classified particle size distributions (PSDs). This study examines the influence of size-classified fillers [ie, limestone (CaCO₃), quartz (SiO₂), corundum (Al₂O₃), and rutile (TiO₂)] on early-age hydration kinetics of tricalcium silicate (C₃S) using a combination of experimental methods, while also employing a modified phase boundary and nucleation and growth model. In prior studies, wherein fillers with broad PSDs were used, it has been reported that between quartz and limestone, the latter is a superior filler due to its ability to partake in anion-exchange reactions with C-S-H. Contrary to prior investigations, this study shows that when size-classified and area matched fillers are used—which, essentially, eliminate degrees of freedom associated with surface area and agglomeration of filler particulates—the filler effect of quartz is broadly similar to that of limestone as well as rutile. Results also show that unlike quartz, limestone, and rutile—which enhance C₃S hydration kinetics—corundum suppresses hydration of C₃S during the first several hours after mixing. Such deceleration in C₃S hydration kinetics is attributed to the adsorption of aluminate anions—released from corundum's dissolution—onto anhydrous particulates’ surfaces, which impedes both the dissolution of C₃S and heterogeneous nucleation of C-S-H.     

Factors Affecting the Study of Chemistry in Different Countries Around the World: Findings from an International Survey

Improving teaching and student learning in chemistry classrooms is an important goal that is constantly researched. Several comparative studies of science teaching have been carried out on different parameters, e. g. misconceptions which science teachers and students may have regarding the scientific concepts they learn and teach. Here we describe science teaching in general, and chemistry teaching in particular, in 12 countries including Israel. Different parameters are compared, including the hours that are devoted to science, the subjects included, the pedagogy, and teachers′ salaries. The survey covers all school levels: elementary school, secondary school and high school. At the high‐school level, the comparison focused on chemistry studies. In this study the variances variables, such as the hours that are allocated for science teaching, did not show an appreciable effect on students′ achievements. It was also found that, in countries where chemistry studies at the high‐school level are not mandatory, innovative pedagogies are more likely to replace the traditional chemistry teaching methods where chemistry is taught according to the structure of the subject based on basic concepts that underlie the curriculum. The study provided an additional support to the importance of the professional development of science and chemistry teachers and suggest that the autonomy that is given to them could influence the quality of science teaching and students′ achievements.     

Modeling the influence of changes in aliphatic structure on char surface area during coal pyrolysis

The influence of changes in aliphatic structure on char surface area during coal pyrolysis was modeled, and the effect was introduced to a previous char surface area model for lignite pyrolysis established based on the chemical percolation devolatilization (CPD) model. The modified model can predict not only the N₂ and CO₂ char surface area during rapid pyrolysis of three lignites but also the CO₂ char surface area of two high-volatile bituminous coals; the agreement of the modified model with experiments is improved at high temperatures. The decrease in aliphatic chain length can reduce adsorption positions around aromatic core, and decrease char surface area. When mass release is more than 55% at about 1,100 K, the predicted N₂ char surface area starts to decrease with further generation of volatiles, and the increase of predicted CO₂ char surface area with increasing generation of volatiles also become slow at the end of mass release.     

Effect of network mesh size and swelling to the drug delivery from pH responsive hydrogels

pH responsive hydrogels are ideal platforms for numerous therapeutic delivery applications, including oral delivery, as they are capable of overcoming the many barriers that must be considered when creating an effective drug delivery system. Understanding of the innate hydrogel network structure and its swelling behavior at environmentally relevant conditions is vital for designing hydrogel network capable of effective controlled drug release. Herein, we explored how to expand traditional techniques of swelling and pore characterization to gain better insight into the performance of anionic microparticles composed of the poly(methyl methacrylate-co-acrylic acid) with varying molar percentage of 10, 20, and 30 mol% of MMA, for controlled release of low-molecular-weight drugs. By evaluating these carrier systems at environmental conditions, we can observe changes in swelling and pore size of the anionic hydrogel networks as a function of MMA, which was then correlated with the release profiles of the small-molecular-weight drug sodium nitrate. With the correlation of the swelling behavior of the networks and the release profiles, we demonstrated how the expansion of swelling parameters at relevant pH values provides further incite for evaluating for the optimal blend for controlled release. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48767.     

The effect of external flow on the feeding currents of sessile microorganisms

Microscopic sessile suspension feeders live attached to surfaces and, by consuming bacteria-sized prey and by being consumed, they form an important part of aquatic ecosystems. Their environmental impact is mediated by their feeding rate, which depends on a self-generated feeding current. The feeding rate has been hypothesized to be limited by recirculating eddies that cause the organisms to feed from water that is depleted of food particles. However, those results considered organisms in still water, while ambient flow is often present in their natural habitats. We show, using a point-force model, that even very slow ambient flow, with speed several orders of magnitude less than that of the self-generated feeding current, is sufficient to disrupt the eddies around perpendicular suspension feeders, providing a constant supply of food-rich water. However, the feeding rate decreases in external flow at a range of non-perpendicular orientations due to the formation of recirculation structures not seen in still water. We quantify the feeding flow and observe such recirculation experimentally for the suspension feeder Vorticella convallaria in external flows typical of streams and rivers.