Effects of Ta Content on Thermodynamic Properties and Transformation Temperatures of Shape Memory NiTi Alloy

Metals and Materials International - In the present work, Ni32-x-Ti-Ta18+x (x?=?0, 2, 3, 4, 5, 6, 7, 8) shape memory alloys, produced by arc-melting method. Then, differential scanning...     

Synthetic Melanin Acts as Efficient Peptide Carrier in Cancer Vaccine Strategy

We previously reported that a novel peptide vaccine platform, based on synthetic melanin nanoaggregates, triggers strong cytotoxic immune responses and significantly suppresses tumor growth in mice. However, the mechanisms underlying such an efficacy remained poorly described. Herein, we investigated the role of dendritic cells (DCs) in presenting the antigen embedded in the vaccine formulation, as well as the potential stimulatory effect of melanin upon these cells, in vitro by coculture experiments and ELISA/flow cytometry analysis. The vaccine efficiency was evaluated in FLT3-L^−/− mice constitutively deficient in DC1, DC2, and pDCs, in Zbtb46^DTR chimera mice deficient in DC1 and DC2, and in Langerin^DTR mice deficient in dermal DC1 and Langerhans cells. We concluded that DCs, and especially migratory conventional type 1 dendritic cells, seem crucial for mounting the immune response after melanin-based vaccination. We also assessed the protective effect of L-DOPA melanin on peptides from enzymatic digestion, as well as the biodistribution of melanin–peptide nanoaggregates, after subcutaneous injection using [¹⁸F]MEL050 PET imaging in mice. L-DOPA melanin proved to act as an efficient carrier for peptides by fully protecting them from enzymatic degradation. L-DOPA melanin did not display any direct stimulatory effects on dendritic cells in vitro. Using PET imaging, we detected melanin–peptide nanoaggregates up to three weeks after subcutaneous injections within the secondary lymphoid tissues, which could explain the sustained immune response observed (up to 4 months) with this vaccine technology.     

Insights into the Structure of the Highly Glycosylated Ffase from Rhodotorula dairenensis Enhance Its Biotechnological Potential

Rhodotorula dairenensis β-fructofuranosidase is a highly glycosylated enzyme with broad substrate specificity that catalyzes the synthesis of 6-kestose and a mixture of the three series of fructooligosaccharides (FOS), fructosylating a variety of carbohydrates and other molecules as alditols. We report here its three-dimensional structure, showing the expected bimodular arrangement and also a unique long elongation at its N-terminus containing extensive O-glycosylation sites that form a peculiar arrangement with a protruding loop within the dimer. This region is not required for activity but could provide a molecular tool to target the dimeric protein to its receptor cellular compartment in the yeast. A truncated inactivated form was used to obtain complexes with fructose, sucrose and raffinose, and a Bis-Tris molecule was trapped, mimicking a putative acceptor substrate. The crystal structure of the complexes reveals the major traits of the active site, with Asn387 controlling the substrate binding mode. Relevant residues were selected for mutagenesis, the variants being biochemically characterized through their hydrolytic and transfructosylating activity. All changes decrease the hydrolytic efficiency against sucrose, proving their key role in the activity. Moreover, some of the generated variants exhibit redesigned transfructosylating specificity, which may be used for biotechnological purposes to produce novel fructosyl-derivatives.     

Allosteric Inhibition of Neutral Sphingomyelinase 2 (nSMase2) by DPTIP: From Antiflaviviral Activity to Deciphering Its Binding Site through In Silico Studies and Experimental Validation

Flavivirus comprises globally emerging and re-emerging pathogens such as Zika virus (ZIKV), Dengue virus (DENV), and West Nile virus (WNV), among others. Although some vaccines are available, there is an unmet medical need as no effective antiviral treatment has been approved for flaviviral infections. The development of host-directed antivirals (HDAs) targeting host factors that are essential for viral replication cycle offers the opportunity for the development of broad-spectrum antivirals. In the case of flaviviruses, recent studies have revealed that neutral sphingomyelinase 2, (nSMase2), involved in lipid metabolism, plays a key role in WNV and ZIKV infection. As a proof of concept, we have determined the antiviral activity of the non-competitive nSMase2 inhibitor DPTIP against WNV and ZIKV virus. DPTIP showed potent antiviral activity with EC₅₀ values of 0.26 µM and 1.56 µM for WNV and ZIKV, respectively. In order to unravel the allosteric binding site of DPTIP in nSMase2 and the details of the interaction, computational studies have been carried out. These studies have revealed that DPTIP could block the DK switch in nSMase2. Moreover, the analysis of the residues contributing to the binding identified His463 as a crucial residue. Interestingly, the inhibitory activity of DPTIP on the H463A mutant protein supported our hypothesis. Thus, an allosteric cavity in nSMase2 has been identified that can be exploited for the development of new inhibitors with anti-flaviviral activity.     

Conjugates of Methylene Blue with Cycloalkaneindoles as New Multifunctional Agents for Potential Treatment of Neurodegenerative Disease

The development of multi-target-directed ligands (MTDLs) would provide effective therapy of neurodegenerative diseases (ND) with complex and nonclear pathogenesis. A promising method to create such potential drugs is combining neuroactive pharmacophoric groups acting on different biotargets involved in the pathogenesis of ND. We developed a synthetic algorithm for the conjugation of indole derivatives and methylene blue (MB), which are pharmacophoric ligands that act on the key stages of pathogenesis. We synthesized hybrid structures and performed a comprehensive screening for a specific set of biotargets participating in the pathogenesis of ND (i.e., cholinesterases, NMDA receptor, mitochondria, and microtubules assembly). The results of the screening study enabled us to find two lead compounds (4h and 4i) which effectively inhibited cholinesterases and bound to the AChE PAS, possessed antioxidant activity, and stimulated the assembly of microtubules. One of them (4i) exhibited activity as a ligand for the ifenprodil-specific site of the NMDA receptor. In addition, this lead compound was able to bypass the inhibition of complex I and prevent calcium-induced mitochondrial depolarization, suggesting a neuroprotective property that was confirmed using a cellular calcium overload model of neurodegeneration. Thus, these new MB-cycloalkaneindole conjugates constitute a promising class of compounds for the development of multitarget neuroprotective drugs which simultaneously act on several targets, thereby providing cognitive stimulating, neuroprotective, and disease-modifying effects.     

Revealing the Changes in Saliva and Serum Proteins of Pigs with Meningitis Caused by Streptococcus Suis: A Proteomic Approach

Meningitis due to Streptococcus suis causes high mortality and morbidity on pig farms and has increasing zoonotic potential worldwide. Saliva proteome analysis would potentially be useful in elucidating pathophysiological changes and mining for new biomarkers to diagnose and monitor S. suis infection. The objective of this study was to investigate the changes in the salivary and serum proteome profile of piglets with meningitis. The LC-MS/MS TMT proteomic approach was used to analyze saliva and serum samples from 20 male piglets: 10 with meningitis and 10 healthy. In saliva, 11 proteins had higher and 10 had lower relative abundance in piglets with meningitis. The proteins with the highest relative abundance were metavinculin (VCL) and desmocollin-2 (DSC2). Adenosine deaminase (ADA) was selected for validation using a spectrophotometric assay and demonstrated excellent performance in the differentiation between healthy and pigs with meningitis due to S. suis. In serum, the most protruding changes occurred for one SERPIN and haptoglobin (HP). In saliva and serum, the highest number of proteins with altered abundance were linked, via the enrichment analysis, with platelet and neutrophil pathways. Overall, meningitis caused by S. suis resulted in specific proteome changes in saliva and serum, reflecting different pathophysiological mechanisms, and marking new potential biomarkers for this infection.     

Therapeutic Potential of Extracellular Vesicles in Aging and Age-Related Diseases

Aging is associated with an alteration of intercellular communication. These changes in the extracellular environment contribute to the aging phenotype and have been linked to different aging-related diseases. Extracellular vesicles (EVs) are factors that mediate the transmission of signaling molecules between cells. In the aging field, these EVs have been shown to regulate important aging processes, such as oxidative stress or senescence, both in vivo and in vitro. EVs from healthy cells, particularly those coming from stem cells (SCs), have been described as potential effectors of the regenerative potential of SCs. Many studies with different animal models have shown promising results in the field of regenerative medicine. EVs are now viewed as a potential cell-free therapy for tissue damage and several diseases. Here we propose EVs as regulators of the aging process, with an important role in tissue regeneration and a raising therapy for age-related diseases.     

Association between LAG3/CD4 Genes Variants and Risk for Multiple Sclerosis

Several recent works have raised the possibility of the contribution of the lymphocyte activation gene 3 (LAG3) protein in the inflammatory processes of multiple sclerosis (MS). Results of studies on the possible association between LAG3 gene variants and the risk of MS have been inconclusive. In this study, we tried to show the possible association between the most common single nucleotide variants (SNVs) in the CD4 and LAG3 genes (these two genes are closely related) and the risk of MS in the Caucasian Spanish population. We studied the genotypes and allelic variants CD4 rs1922452, CD4 rs951818, and LAG3 rs870849 in 300 patients diagnosed with MS and 400 healthy patients using specific TaqMan-based qPCR assays. We analyzed the possible influence of the genotype frequency on age at the onset of MS, the severity of MS, clinical evolutive subtypes of MS, and the HLADRB1*1501 genotype. The frequencies of the CD4 rs1922452, CD4 rs951818, and LAG3 rs870849 genotypes and allelic variants were not associated with the risk of MS and were unrelated to gender, age at onset and severity of MS, the clinical subtype of MS, and HLADRB1*1501 genotype. The results of the current study showed a lack of association between the CD4 rs1922452, CD4 rs951818, and LAG3 rs870849 SNVs and the risk of developing MS in the Caucasian Spanish population.     

Study of the Electrochemical Behavior of N-Substituted-4-Piperidones Curcumin Analogs: A Combined Experimental and Theoretical Approach

The electrochemical behavior of N-methyl- and N-benzyl-4-piperidone curcumin analogs were studied experimentally and theoretically. The studied compounds present different substituents at the para position in the phenyl rings (-H, -Br, -Cl, -CF₃, and -OCH₃). We assessed their electrochemical behavior by differential pulse and cyclic voltammetry, while we employed density functional theory (DFT) M06 and M06-2x functionals along with 6-311+G(d,p) basis set calculations to study them theoretically. The results showed that compounds suffer a two-electron irreversible oxidation in the range of 0.72 to 0.86 V, with surface concentrations ranging from 1.72 × 10⁻⁷ to 5.01 × 10⁻⁷ mol/cm². The results also suggested that the process is diffusion-controlled for all compounds. M06 DFT calculations showed a better performance than M06-2x to obtain oxidation potentials. We found a good correlation between the experimental and theoretical oxidation potential for N-benzyl-4-piperidones (R² = 0.9846), while the correlation was poor for N-methyl-4-piperidones (R² = 0.3786), suggesting that the latter suffer a more complex oxidation process. Calculations of the BDEs for labile C-H bonds in the compounds suggested that neither of the two series of compounds has a different tendency for a proton-coupled electron transfer (PCET) oxidation process. It is proposed that irreversible behavior is due to possible dimerization of the compounds by Shono-type oxidation.     

Overexpression of TcNTPDase-1 Gene Increases Infectivity in Mice Infected with Trypanosoma cruzi

Ecto-nucleoside triphosphate diphosphohydrolases (NTPDases) are enzymes located on the surface of the T. cruzi plasma membrane, which hydrolyze a wide range of tri-/-diphosphate nucleosides. In this work, we used previously developed genetically modified strains of Trypanosoma cruzi (T. cruzi), hemi-knockout (KO +/−) and overexpressing (OE) the TcNTPDase-1 gene to evaluate the parasite infectivity profile in a mouse model of acute infection (n = 6 mice per group). Our results showed significantly higher parasitemia and mortality, and lower weight in animals infected with parasites OE TcNTPDase-1, as compared to the infection with the wild type (WT) parasites. On the other hand, animals infected with (KO +/−) parasites showed no mortality during the 30-day trial and mouse weight was more similar to the non-infected (NI) animals. In addition, they had low parasitemia (45.7 times lower) when compared with parasites overexpressing TcNTPDase-1 from the hemi-knockout (OE KO +/−) group. The hearts of animals infected with the OE KO +/− and OE parasites showed significantly larger regions of cardiac inflammation than those infected with the WT parasites (p < 0.001). Only animals infected with KO +/− did not show individual electrocardiographic changes during the period of experimentation. Together, our results expand the knowledge on the role of NTPDases in T. cruzi infectivity, reenforcing the potential of this enzyme as a chemotherapy target to treat Chagas disease (CD).