Melatonin Prevents Early but Not Delayed Ventricular Fibrillation in the Experimental Porcine Model of Acute Ischemia

Antiarrhythmic effects of melatonin have been demonstrated ex vivo and in rodent models, but its action in a clinically relevant large mammalian model remains largely unknown. Objectives of the present study were to evaluate electrophysiological and antiarrhythmic effects of melatonin in a porcine model of acute myocardial infarction. Myocardial ischemia was induced by 40-min coronary occlusion in 25 anesthetized pigs. After ischemia onset, 12 animals received melatonin (4 mg/kg). 48 intramyocardial electrograms were recorded from left ventricular wall and interventricular septum (IVS). In each lead, activation time (AT) and repolarization time (RT) were determined. During ischemia, ATs and dispersion of repolarization (DOR = RTmax − RTmin) increased reaching maximal values by 3–5 and 20–25 min, respectively. Ventricular fibrillation (VF) incidence demonstrated no relations to redox state markers and was associated with increased DOR and delayed ATs (specifically, in an IVS base, an area adjacent to the ischemic zone) (p = 0.031). Melatonin prevented AT increase in the IVS base, (p < 0.001) precluding development of early VF (1–5 min, p = 0.016). VF occurrence in the delayed phase (17–40 min) where DOR was maximal was not modified by melatonin. Thus, melatonin-related enhancement of activation prevented development of early VF in the myocardial infarction model.     

New hard ternary Hf–Ir–B borides formed by reaction hafnium diboride with iridium

A variety of the ternary Hf–Ir–B phases formed via the reaction between iridium and hafnium diboride at elevated temperatures was found. The data on the phase and elemental composition, as well as crystal structure, obtained by powder and single-crystal X-ray diffraction, scanning electron microscopy/energy-dispersive X-ray spectrometer, and time-of-flight neutron diffraction analysis unambiguously confirm that HfIr₃B_x solid solution, two known ternary borides (HfIr₃B₄, Hf₂Ir₅B₂), as well as two novel ternary HfIr_2.1B_1.3 and HfIr_5.7B_2.7 phases, are formed at elevated temperatures. This result is fundamentally different from that previously obtained by us for the Hf–Ir–C system in which only one binary intermetallic compound, HfIr₃, was produced. The measured Vickers microhardness for all the aforementioned ternary borides (13–19 GPa) allows us to consider them hard. The coefficients of thermal expansion of ternary borides were measured by in situ high-temperature X-ray analysis.     

Antistress Action of Melanocortin Derivatives Associated with Correction of Gene Expression Patterns in the Hippocampus of Male Rats Following Acute Stress

Natural melanocortins (MCs) have been used in the successful development of drugs with neuroprotective properties. Here, we studied the behavioral effects and molecular genetic mechanisms of two synthetic MC derivatives-ACTH(4–7)PGP (Semax) and ACTH(6–9)PGP under normal and acute restraint stress (ARS) conditions. Administration of Semax or ACTH(6–9)PGP (100 μg/kg) to rats 30 min before ARS attenuated ARS-induced behavioral alterations. Using high-throughput RNA sequencing (RNA-Seq), we identified 1359 differentially expressed genes (DEGs) in the hippocampus of vehicle-treated rats subjected to ARS, using a cutoff of >1.5 fold change and adjusted p-value (Padj) < 0.05, in samples collected 4.5 h after the ARS. Semax administration produced > 1500 DEGs, whereas ACTH(6–9)PGP administration led to <400 DEGs at 4.5 h after ARS. Nevertheless, ~250 overlapping DEGs were identified, and expression of these DEGs was changed unidirectionally by both peptides under ARS conditions. Modulation of the expression of genes associated with biogenesis, translation of RNA, DNA replication, and immune and nervous system function was produced by both peptides. Furthermore, both peptides upregulated the expression levels of many genes that displayed decreased expression after ARS, and vice versa, the MC peptides downregulated the expression levels of genes that were upregulated by ARS. Consequently, the antistress action of MC peptides may be associated with a correction of gene expression patterns that are disrupted during ARS.     

Electrochemistry and XPS study of an imidazoline as corrosion inhibitor of mild steel in an acidic environment

The effect of 2‐(2‐heptadec‐8‐enyl‐4,5‐dihydro‐imidazol‐1‐yl)‐ethylamine on the corrosion behavior of mild steel in aqueous hydrochloric acid was investigated using weight loss measurements, polarization scans, electrochemical impedance, and X‐ray photoelectron spectroscopy (XPS). The inhibition efficiencies and coverage degrees increased with the concentration of inhibitor but decreased proportionally with temperature. It appears that the steric hindrance of the aliphatic chain on the imidazoline ring adsorption may affect inhibitor efficiency. Polarization curves showed that the oleic imidazoline (OI) acted essentially as a mixed type inhibitor, in which the blocking of active sites occurred. As a result of film formation, impedance spectra revealed a considerable increase in the charge transfer resistance as indicated by the second capacitive loop. XPS depth profile analysis observed the presence of nitrogen and carbon species on the inhibitor film, which were associated to the OI.     

Plant_SNP_TATA_Z-Tester: A Web Service That Unequivocally Estimates the Impact of Proximal Promoter Mutations on Plant Gene Expression

Synthetic targeted optimization of plant promoters is becoming a part of progress in mainstream postgenomic agriculture along with hybridization of cultivated plants with wild congeners, as well as marker-assisted breeding. Therefore, here, for the first time, we compiled all the experimental data—on mutational effects in plant proximal promoters on gene expression—that we could find in PubMed. Some of these datasets cast doubt on both the existence and the uniqueness of the sought solution, which could unequivocally estimate effects of proximal promoter mutation on gene expression when plants are grown under various environmental conditions during their development. This means that the inverse problem under study is ill-posed. Furthermore, we found experimental data on in vitro interchangeability of plant and human TATA-binding proteins allowing the application of Tikhonov’s regularization, making this problem well-posed. Within these frameworks, we created our Web service Plant_SNP_TATA_Z-tester and then determined the limits of its applicability using those data that cast doubt on both the existence and the uniqueness of the sought solution. We confirmed that the effects (of proximal promoter mutations on gene expression) predicted by Plant_SNP_TATA_Z-tester correlate statistically significantly with all the experimental data under study. Lastly, we exemplified an application of Plant_SNP_TATA_Z-tester to agriculturally valuable mutations in plant promoters.     

The Levels of Ghrelin,Glucagon, Visfatin and Glp-1 Are Decreased in the Peritoneal Fluid of Women with Endometriosis along with the Increased Expression of the CD10 Protease by the Macrophages

The aim of this study was to evaluate the levels of ten energy metabolism factors: C-peptide, ghrelin, GIP, GLP-1, glucagon, insulin, leptin, PAI-1 (total), resistin, and visfatin, and to determine the expression of GLP1R receptors, CD10, CD26 proteases, and pro-inflammatory marker CD86 by macrophages in the peritoneal fluid (PF) in patients with endometriosis. The study included 54 women with endometriosis and a control group of 30 women with uterine myoma without signs of endometriosis. The levels of factors in PF were assessed by a multiplex method. Expression of GLP1R receptors, CD10, CD26 proteases, and CD86 by macrophages was evaluated using flow cytometry. It was found that in women with endometriosis, the concentrations of ghrelin, GLP-1, glucagon, and visfatin in PF were reduced (p = 0.007, p = 0.009, p = 0.002, p = 0.008, respectively). At the same time, there was a noted increase in the CD10 protease expression by peritoneal macrophages (p = 0.044). Correlation analysis showed a positive correlation of ghrelin and GLP-1 levels with CD86 macrophage expression (p = 0.044, p = 0.022, respectively) in the study group; a positive correlation was also found between the levels of GLP-1, glucagon, and visfatin with CD26 macrophage expression (p = 0.041, p = 0.048, p = 0.015, respectively) in PF. No correlations were found in the control group. These results indicate that a decrease in the levels of ghrelin, GLP-1, glucagon, and visfatin in PF may contribute to endometriosis development through their impact on the expression of pro-inflammatory markers of PF macrophages.     

Erosion of carbon fiber composites under high-fluence heavy ion irradiation

The ion-induced erosion, determining by sputtering yield Y and surface evolution including structure and morphology changes of the modified surface layers, of two commercial carbon fiber composites (CFC) with different reinforcement - KUP-VM (1D) and Desna 4 (4D) have been studied under 30 keV Ar⁺ high fluence (φt ∼ 10¹⁸-10²⁰ ion/cm²) irradiation in the temperature range from room temperature to 400 °C. Ion-induced erosion results in the changes of carbon fiber structure which depend on temperature and ion fluence. Monitoring of ion-induced structural changes using the temperature dependence of ion-induced electron emission yield has shown that for Desna 4 and KUP-VM at dynamic annealing temperature Т_а ≈ 170 °С the transition takes place from disordering at T < T_a to recrystallization at T > T_a. The annealing temperature Т_а is close to the one for polycrystalline graphites. Microscopy analysis has shown that at temperatures Т < T_a the etching of the fibers results in a formation of trough-like longitudinal cavities and hillocks. Irradiation at temperatures T > T_a leads to a crimped structure with the ribs perpendicular to fiber axis. After further sputtering of the crimps the fiber morphology is transformed to an isotropic globular structure. As a result the sputtering yield decreases for Desna 4 more than twice. This value is almost equal to that for KUP-VM, Desna 4, polycrystalline graphites and glassy carbons at room temperature.     

A versatile approach to develop porous hydrogels with a regular pore distribution and investigation of their physicomechanical properties

Porous polyacrylamide (PAAm) hydrogels with enhanced mechanical properties and regular pore distribution have been synthesized by a unique and facile methodology, which involves formation of the hydrogel pores by leaching out chemically modified silica particles. To improve the pore distribution and mechanical properties of the hydrogel network, porogen particles have been modified with PAAm chains chemically attached to the silica surface. Grafting polymerization initiated by peroxide groups immobilized on the particle surface has been used for this modification. The grafted PAAm layer on the silica surface improves the dispersibility of the porogen material in the hydrogel composition, and simultaneously forms pore “walls” reinforcing the hydrogel network, after leaching out the silica particles. The proposed synthetic way for the development of porous hydrogels includes three steps: (i) tethering of PAAm chains to silica particles due to the grafting polymerization initiated by an adsorbed polyperoxide macroinitiator (PPM), (ii) simultaneous crosslinking of grafted PAAm chains and PAAm forming hydrogel network, and (iii) pore formation by leaching out silica particles in the presence of hydrofluoric acid. The PPM has been synthesized by a free radical copolymerization of the peroxide monomer (PM) N‐(tert‐butylperoxymethyl)acrylamide with acrylamide. Both PM and PPM have been developed in our lab, and applied for the synthesis of porous polymeric hydrogels. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Paradoxical acceleration of dithiothreitol-induced aggregation of insulin in the presence of a chaperone

The kinetics of dithiothreitol (DTT)-induced aggregation of human recombinant insulin and the effect of α-crystallin, a representative of the family of small heat shock proteins, on the aggregation process have been studied using dynamic light scattering technique. Analysis of the distribution of the particles by size measured in the course of aggregation showed that the initial stage of the aggregation process was the stage of formation of the start aggregates with a hydrodynamic radius (R(h)) of about 90 nm. When studying the effect of α-crystallin on the rate of DTT-induced aggregation of insulin, it was demonstrated that low concentrations of α-crystallin dramatically accelerated the aggregation process, whereas high concentrations of α-crystallin suppressed insulin aggregation. In the present study, at the molar stoichiometric ratio (insulin:α-crystallin) less than 1:0.5, a pronounced accelerating effect of α-crystallin was observed; whereas a ratio exceeding the value of 1:0.6 caused suppression of insulin aggregation. The mechanisms underlying the dual effect of α-crystallin have been proposed. It is assumed that heterogeneous nucleation occurring on the surface of the α-crystallin particle plays the key role in the paradoxical acceleration of insulin aggregation by α-crystallin that may provide an alternative biologically significant pathway of the aggregation process.