Preparation of novel porous calcium silicate scaffold loaded by celecoxib drug using freeze drying technique: Fabrication,characterization and simulation

In the current investigation, the microarchitecture of bio-nanocomposite scaffold, which is fabricated by natural synthetic diopside and composed of magnetite nanoparticles (MNPs), is considered. The MNPs are tested with various weight fractions (0, 5, 10, and 15 wt%) and are manufactured by the freeze-drying technique using sodium alginate as base matrix for the first time. Due to the limitation of the mechanical properties of calcium phosphates (CaPs) and bioactive glasses (BG), clinical usage of calcium silicate ceramics (CSC) are greatly affected. Therefore, CSCs are produced with the incorporation of metal oxides into the base binary xCaO-ySiO₂, as well as the substitution of calcium ions. Furthermore, mechanical and biological properties of CSCs are enhanced, which are a result of the ability to give out bioactive ions and their distinct compositions. After that, the porous bio-nanocomposite scaffolds are investigated for biological and mechanical properties corresponding to hardness versus elastic modulus, apatite formation versus biodegradation rate, wetting properties versus roughness and electrical conductivity of the sample. Then, the composition, microstructure, and physical characteristics are also examined using different techniques such as X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) which is equipped with energy-dispersive X-ray spectroscopy (EDX). The obtained outcomes show that addition of diopside bioceramic enhances the mechanical and physical properties of the samples. It is shown that the prepared porous bio-nanocomposite scaffolds, containing 10 wt% MNPs, represents a better agreement in serving as a bone graft for the cancer disease treatment and hyperthermia term. The results indicate that the specimen with 10 wt% MNPs in the bio-nanocomposite release the celecoxib drug easier, however, its has better porosity and mechanical behavior that make it suitable candidate for bone implantations.     

Rational Design and Identification of Harmine-Inspired,N-Heterocyclic DYRK1A Inhibitors Employing a Functional Genomic In Vivo Drosophila Model System**

Deregulation of dual-specificity tyrosine phosphorylation-regulated kinase 1A (DYRK1A) plays a significant role in developmental brain defects, early-onset neurodegeneration, neuronal cell loss, dementia, and several types of cancer. Herein, we report the discovery of three new classes of N-heterocyclic DYRK1A inhibitors based on the potent, yet toxic kinase inhibitors, harmine and harmol. An initial in vitro evaluation of the small molecule library assembled revealed that the core heterocyclic motifs benzofuranones, oxindoles, and pyrrolones, showed statistically significant DYRK1A inhibition. Further, the utilization of a low cost, high-throughput functional genomic in vivo model system to identify small molecule inhibitors that normalize DYRK1A overexpression phenotypes is described. This in vivo assay substantiated the in vitro results, and the resulting correspondence validates generated classes as architectural motifs that serve as potential DYRK1A inhibitors. Further expansion and analysis of these core compound structures will allow discovery of safe, more effective chemical inhibitors of DYRK1A to ameliorate phenotypes caused by DYRK1A overexpression.     

Structural Basis for the Functional Diversity of Centrins: A Focus on Calcium Sensing Properties and Target Recognition

Centrins are a family of small, EF hand-containing proteins that are found in all eukaryotes and are often complexed with centrosome-related structures. Since their discovery, centrins have attracted increasing interest due to their multiple, diverse cellular functions. Centrins are similar to calmodulin (CaM) in size, structure and domain organization, although in contrast to CaM, the majority of centrins possess at least one calcium (Ca²⁺) binding site that is non-functional, thus displaying large variance in Ca²⁺ sensing abilities that could support their functional versatility. In this review, we summarize current knowledge on centrins from both biophysical and structural perspectives with an emphasis on centrin-target interactions. In-depth analysis of the Ca²⁺ sensing properties of centrins and structures of centrins complexed with target proteins can provide useful insight into the mechanisms of the different functions of centrins and how these proteins contribute to the complexity of the Ca²⁺ signaling cascade. Moreover, it can help to better understand the functional redundancy of centrin isoforms and centrin-binding proteins.     

On the Use of Side-Chain NMR Relaxation Data to Derive Structural and Dynamical Information on Proteins: A Case Study Using Hen Lysozyme

Values of and order parameters derived from NMR relaxation measurements on proteins cannot be used straightforwardly to determine protein structure because they cannot be related to a single protein structure, but are defined in terms of an average over a conformational ensemble. Molecular dynamics simulation can generate a conformational ensemble and thus can be used to restrain and order parameters towards experimentally derived target values (exp) and (exp). Application of and order-parameter restraining MD simulation to bond vectors in 63 side chains of the protein hen egg white lysozyme using 51 (exp) target values and 28 (exp) target values shows that a conformational ensemble compatible with the experimentally derived data can be obtained by using this technique. It is observed that order-parameter restraining of C−H bonds in methyl groups is less reliable than order-parameter restraining because of the possibly less valid assumptions and approximations used to derive experimental (exp) values from NMR relaxation measurements and the necessity to adopt the assumption of uniform rotational motion of methyl C−H bonds around their symmetry axis and of the independence of these motions from each other. The restrained simulations demonstrate that side chains on the protein surface are highly dynamic. Any hydrogen bonds they form and that appear in any of four different crystal structures, are fluctuating with short lifetimes in solution.     

A Multioptimization Approach to Assessment of Drug Delivery of PLGA Nanoparticles: Simultaneous Control of Particle Size and Release Behavior

A multiple optimization strategy was implemented on the experimental data obtained in this study to assess drug-delivery behavior of poly(D,L-lactide-co-glycolide) (PLGA) particles. Albumin–fluorescein isothiocyanate conjugate (FITC-albumin)-loaded PLGA micro- and nanoparticles were prepared by water-in-oil-in-water double emulsion method. The experiments were carried out based on L8 Taguchi design where the effects of PLGA molecular weight, PLGA concentration in the oil phase, and sonication rate in the second emulsification step of preparation process on particle size and percentage of initial burst release of PLGA were discussed. Multioptimization toward PLGA particle size and initial burst elucidated that all aforementioned variables affect the characteristics of PLGA particles, but PLGA molecular weight was appeared as the most significant factor among studied variables. Multifarious optimizations were tested and executed varying the aforementioned factors to minimize both the size and percentage of initial burst of PLGA particles. The FTIR experiment of the optimal formulation showed the successful incorporation of the drug into the particles. These results enable careful selection and definition of optimal process parameters for the preparation of PLGA nanoparticles with sustained release properties. Furthermore, the methodology developed in this work introduces a useful tool to meet a drug delivery system with optimal release behavior.     

Surprising Structural and Functional Properties of Favism Erythrocytes Are Linked to Special Metabolic Regulation: A Cell Aging Study

Favism uniquely arises from a genetic defect of the Glucose-6 Phosphate Dehydrogenase (G6PD) enzyme and results in a severe reduction of erythrocytes’ (RBCs) reducing power that impairs the cells’ ability to respond to oxidative stresses. After exposure to fava beans or a few other drugs, the patients experience acute hemolytic anemia due to RBCs’ lysis both intra and extra-vascularly. In the present paper, we compared selected biochemical, biophysical, and ultra-morphological properties of normal RBCs and cells from favism patients measured along cellular aging. Along the aging path, the cells’ characteristics change, and their structural and functional properties degrade for both samples, but with different patterns and effectors that have been characterized in biophysical and biochemical terms. In particular, the analysis revealed distinct metabolic regulation in G6DP-deficient cells that determines important peculiarities in the cell properties during aging. Remarkably, the initial higher fragility and occurrence of structural/morphological alterations of favism cells develop, with longer aging times, into a stronger resistance to external stresses and higher general resilience. This surprisingly higher endurance against cell aging has been related to a special mechanism of metabolic regulation that permits lower energy consumption in environmental stress conditions. Our results provided a direct and coherent link between the RBCs’ metabolic regulation and the cell properties that would not have been possible to establish without an investigation performed during aging. The consequences of this new knowledge, in particular, can be discussed in a more general context, such as understanding the role of the present findings in determining the characteristics of the favism pathology as a whole.