Identification of Hck Inhibitors As Hits for the Development of Antileukemia and Anti‐HIV Agents

Hematopoietic cell kinase (Hck) is a member of the Src family of non‐receptor protein tyrosine kinases. High levels of Hck are associated with drug resistance in chronic myeloid leukemia. Furthermore, Hck activity has been connected with HIV‐1. Herein, structure‐based drug design efforts were aimed at identifying novel Hck inhibitors. First, an in‐house library of pyrazolo[3,4‐d]pyrimidine derivatives, which were previously shown to be dual Abl and c‐Src inhibitors, was analyzed by docking studies within the ATP binding site of Hck to select the best candidates to be tested in a cell‐free assay. Next, the same computational protocol was applied to screen a database of commercially available compounds. As a result, most of the selected compounds were found active against Hck, with K_i values ranging from 0.14 to 18.4 μM , confirming the suitability of the computational approach adopted. Furthermore, selected compounds showed an interesting antiproliferative activity profile against the human leukemia cell line KU‐812, and one compound was found to block HIV‐1 replication at sub‐toxic concentrations.     

The Efficacy of the Quorum Sensing Inhibitor FS8 and Tigecycline in Preventing Prosthesis Biofilm in an Animal Model of Staphylococcal Infection

We investigated the efficacy of tigecycline and FS8, alone or combined, in preventing prosthesis biofilm in a rat model of staphylococcal vascular graft infection. Graft infections were established in the back subcutaneous tissue of adult male Wistar rats by implantation of Dacron prostheses followed by topical inoculation with 2 × 10⁷ colony-forming units of Staphylococcus aureus, strain Smith diffuse. The study included a control group, a contaminated group that did not receive any antibiotic prophylaxis, and three contaminated groups that received: (i) intraperitoneal tigecycline, (ii) FS8-soaked graft, and (iii) tigecycline plus FS8-soaked graft, respectively. Each group included 15 animals. The infection burden was evaluated by using sonication and quantitative agar culture. Moreover, an in vitro binding-study was performed to quantify the how much FS8 was coated to the surface of the prosthesis. Tigecycline, combined with FS8, against the adherent bacteria showed MICs (2.00 mg/L) and MBCs (4.00 mg/L) four-fold lower with respect to tigecycline alone in in vitro studies. The rat groups treated with tigecycline showed the lowest bacterial numbers (4.4 × 10⁴ ± 1.2 × 10⁴ CFU/mL). The FS8-treated group showed a good activity and significant differences compared to control group with bacterial numbers of 6.8 × 10⁴ ± 2.0 × 10⁴ CFU/mL. A stronger inhibition of bacterial growth was observed in rats treated with a combined FS8 and tigecycline therapy than in those that were singly treated with bacterial numbers of 10¹ CFU/mL graft. In conclusion, the ability to affect biofilm formation as well, its property to be an antibiotic enhancer suggests FS8 as alternative or additional agent to use in conjunction with conventional antimicrobial for prevention of staphylococcal biofilm related infection.     

Influence of the alkyl chain length of HSO3-R-MCM-41 on the esterification of glycerol with fatty acids

Ordered mesoporous materials functionalized with alkyl sulfonic acid groups have been proved to be efficient catalysts for esterification. In this paper we report on the synthesis and characterization of new materials containing simultaneously alkyl groups (vinyl, chloromethyl), that have been sulfonated in a post-synthesis step, and methyl groups. Different techniques have been used to characterize the obtained materials: XRD, TEM, elemental analysis, nitrogen adsorption, TGA, ²⁹Si and ¹³C MAS NMR. Finally, the influence of the different synthesis parameters and functional groups on the behavior of the catalysts in the reaction of esterification of glycerol with lauric and oleic acids has been studied. The catalytic performance of the resulting HSO₃-ethyl-MCM-41, HSO₃-ethyl/methyl-MCM-41 and HSO₃-methyl-MCM-41 new materials is also compared to those of HSO₃-phenyl/methyl-MCM-41 and HSO₃-propyl/methyl-MCM-41 synthesized previously. It has been demonstrated that an optimum balance among parameters such as nature of the organic group which support the sulfonic acid, distance between the sulfonic group and the silica surface, average pore size of the material, etc., allows to obtain catalysts with improved activity and selectivity for these reactions.     

The L467F-F508del Complex Allele Hampers Pharmacological Rescue of Mutant CFTR by Elexacaftor/Tezacaftor/Ivacaftor in Cystic Fibrosis Patients: The Value of the Ex Vivo Nasal Epithelial Model to Address Non-Responders to CFTR-Modulating Drugs

Loss-of-function mutations of the CFTR gene cause cystic fibrosis (CF) through a variety of molecular mechanisms involving altered expression, trafficking, and/or activity of the CFTR chloride channel. The most frequent mutation among CF patients, F508del, causes multiple defects that can be, however, overcome by a combination of three pharmacological agents that improve CFTR channel trafficking and gating, namely, elexacaftor, tezacaftor, and ivacaftor. This study was prompted by the evidence of two CF patients, compound heterozygous for F508del and a minimal function variant, who failed to obtain any beneficial effects following treatment with the triple drug combination. Functional studies on nasal epithelia generated in vitro from these patients confirmed the lack of response to pharmacological treatment. Molecular characterization highlighted the presence of an additional amino acid substitution, L467F, in cis with the F508del variant, demonstrating that both patients were carriers of a complex allele. Functional and biochemical assays in heterologous expression systems demonstrated that the double mutant L467F-F508del has a severely reduced activity, with negligible rescue by CFTR modulators. While further studies are needed to investigate the actual prevalence of the L467F-F508del allele, our results suggest that this complex allele should be taken into consideration as plausible cause in CF patients not responding to CFTR modulators.     

Synthesis,characterization, and DFT Raman study of pure and Mn-doped LiTaO3 nanofibers

Pure and Mn-doped lithium tantalate nanofibers, with Mn concentrations of 1%, 2.5%, and 5%, were synthesized by the electrospinning method. The morphology, microstructure, and crystal structure of as-spun and annealed composite nanofibers were characterized by scanning electron microscopy, X-ray diffraction, and transmission electron microscopy. Raman spectroscopy has shown to be a powerful tool to detect either local variations or changes of the whole structure. Position and width of one Raman line can be used as markers of a structural change. Some vibrational modes are especially associated with the site of Li or Ta ions and so, they can be affected by the introduction of dopant ions. Any damages or local changes in the microstructure can be detected by a line broadening. With the use of Raman spectroscopy, the sites where Mn ions enter the doped structures were established by recording the shift and broadening of peaks in Mn-doped structures with respect to pure lithium tantalate. Thus it was proven that Mn ions enter the Li sites for low Mn concentration and, on the other hand, for higher concentrations, the dopant substitutes Li and Ta sites. First-principles calculations were performed within the density functional theory, including lattice-dynamic calculations of the phonon modes at the zone center (Γ point), for the pure structure, to find the irreducible representation of the modes.     

The critical role of water in spider silk and its consequence for protein mechanics

Due to its remarkable mechanical and biological properties, there is considerable interest in understanding, and replicating, spider silk's stress-processing mechanisms and structure-function relationships. Here, we investigate the role of water in the nanoscale mechanics of the different regions in the spider silk fibre, and their relative contributions to stress processing. We propose that the inner core region, rich in spidroin II, retains water due to its inherent disorder, thereby providing a mechanism to dissipate energy as it breaks a sacrificial amide-water bond and gains order under strain, forming a stronger amide-amide bond. The spidroin I-rich outer core is more ordered under ambient conditions and is inherently stiffer and stronger, yet does not on its own provide high toughness. The markedly different interactions of the two proteins with water, and their distribution across the fibre, produce a stiffness differential and provide a balance between stiffness, strength and toughness under ambient conditions. Under wet conditions, this balance is destroyed as the stiff outer core material reverts to the behaviour of the inner core.     

Toward the discovery of novel anti-HIV drugs. Second-generation inhibitors of the cellular ATPase DDX3 with improved anti-HIV activity: synthesis, structure-activity relationship analysis, cytotoxicity studies, and target validation

A hit optimization protocol applied to the first nonnucleoside inhibitor of the ATPase activity of human DEAD-box RNA helicase DDX3 led to the design and synthesis of second-generation rhodanine derivatives with better inhibitory activity toward cellular DDX3 and HIV-1 replication. Additional DDX3 inhibitors were identified among triazine compounds. Biological data were rationalized in terms of structure-activity relationships and docking simulations. Antiviral activity and cytotoxicity of selected DDX3 inhibitors are reported and discussed. A thorough analysis confirmed human DDX3 as a valid anti-HIV target. The compounds described herein represent a significant advance in the pursuit of novel drugs that target HIV-1 host cofactors.     

The photoinduced charge transfer mechanism in aligned and unaligned carbon nanotubes

Using time-resolved reflectivity measurements on unaligned and aligned bundled single-wall carbon nanotubes with a pump energy of 1.55 eV, quasi-resonant with the second Van Hove singularity of semiconducting tubes, a positive sign of the transient reflectivity is detected in unaligned nanotubes. In contrast a negative sign is detected in aligned nanotubes. This discovery addresses a long-standing question showing that in unaligned nanotubes the stronger intertube interactions favor the formation of short-lived free charge carriers in semiconducting tubes. A detailed analysis of the transient reflectivity spectral response shows that the free carriers in the photo-excited state of semiconducting tubes move towards metallic tubes in about 400 fs.     

Optimization of the procedure to burn textile fabrics by cone calorimeter: Part I. Combustion behavior of polyester

The aim of this study was the optimization of cone calorimeter to determine the burning behavior of textile fabrics. In particular, the combustion behavior of commercial polyester textile fabrics with varying densities was studied in terms of time to ignition (TTI), heat release rate (HRR), and relative peak (pkHRR) were monitored. Reproducibility and repeatability of the data have been verified by the influence of instrument variable including incident heat flux, the temperature of ceramic backing pads and retaining grid used during sample mounting as well as sample weight (as the number of fabric layers), the density of textiles, and the relative humidity. A low reproducibility has been obtained when a wire grid was not used to stabilize samples during the tests. The effects of these variables on TTI and pkHRR were observed. Copyright © 2010 John Wiley & Sons, Ltd.