Theoretical and experimental study of high-pressure synthesized B20-type compounds Mn1−x_{1-x}(Co,Rh)x_xGe

The search and exploration of new materials not found in nature is one of modern trends in pure and applied chemistry. In the present work, we report on experimental and \textit{ab initio} density-functional study of the high-pressure-synthesized series of compounds Mn$_{1-x}$(Co,Rh)$_x$Ge. These high-pressure phases remain metastable at normal conditions, therewith they preserve their inherent noncentrosymmetric B20-type structure and chiral magnetism. Of particular interest in these two isovalent systems is the comparative analysis of the effect of $3d$ (Co) and $4d$ (Rh) substitution for Mn, since the $3d$ orbitals are characterized by higher localization and electron interaction than the $4d$ orbitals. The behavior of Mn$_{1-x}$(Co,Rh)$_x$Ge systems is traced as the concentration changes in the range $0 \leq x \leq 1$. We applied a sensitive experimental and theoretical technique which allowed to refine the shape of the temperature dependencies of magnetic susceptibility $\chi(T)$ and thereby provide a new and detailed magnetic phase diagram of Mn$_{1-x}$Co$_x$Ge. It is shown that both systems exhibit a helical magnetic ordering that very strongly depends on the composition $x$. However, the phase diagram of Mn$_{1-x}$Co$_x$Ge differs from that of Mn$_{1-x}$Rh$_x$Ge in that it is characterized by coexistence of two helices in particular regions of concentrations and temperatures.Comment: 12 pages, 11 figure

BLOOD PLATELETS AS ACTIVATORS AND REGULATORS OF INFLAMMATORY AND IMMUNE REACTIONS. PART 2. THROMBOCYTES AS PARTICIPANTS OF IMMUNE REACTIONS

Thrombocytes keep a leading role in conjugating thrombosis, inflammation and congenital immune responses. The platelets provide stable adhesion and interaction with immune cells. Activated platelets express CD40L (CD154), a membrane glycoprotein of tumor necrosis factor (TNF) family. Hence, the platelets are the main source of sCD40L in blood plasma. Platelet CD154 may interact with CD40 receptor on endothelial cells, causing an inflammatory response, and enhancing production of immunoglobulins by B-lymphocytes. Membrane and soluble CD154 of platelets combined with other signals can induce maturation and activation of dendritic cells (DC). The platelets possess functional receptors, e.g., TLR2, TLR4, TLR7 and TLR9 they also bear Fc-receptors, including FcγRIIA, FcεRI and FcαRIA. FcγRIIA on platelets mediate protection against bacteria. Cross-linking of FcαRI on platelets results in production of prothrombotic and pro-inflammatory mediators such as tissue factor and IL-1β. Activation of platelets via FcεR1 causes release of chemokine RANTES and serotonin, which contribute to the pro-inflammatory response of other immune cells. Platelets possess receptors for activated complement components and its fragments (CR2, CR3, CR4, C1q, C1 inhibitor and factors D and H). Activated platelets trigger the complement system through the release of protein kinases and ATP, and also by phosphorylation of C3 and C3b. α-granules of platelets contain chemokines which represent the most numerous group of antimicrobial proteins of platelets (kinocidins), and there is an antimicrobial protein of the defensin family – hBD-1 in the cytoplasm of platelets. Ligand and receptor of the TNF superfamily (TRAIL and LIGHT), the SDF-1 chemokine (CXCL12), the IL-1βinterleukins, IL-8 and the soluble IL-6 receptor (sRIL-6) are recognized as platelet products belonging to the family of cytokines and their receptors. The HMGB-1 protein classified as an inflammatory cytokine, is expressed by activated platelets and causes formation of the extracellular traps by neutrophils. Platelets produce numerous growth factors, including EGF-α and EGF-β1, EGF-β2, TGF-α and TGF-β1, TGF-β2, PDGF, HGF, FGF-β, IGF, pro- and antiangiogenic factors, e.g., VEGF-F and angiopoietins Ang-1 and Ang-2. Fulfillment of immune functions by the platelets is carried out by their interaction with leukocytes, which are attracted to the site of infection and inflammation and retained during the development of an “immune thrombus” under conditions of high shear stress. Platelets can not only maintain and guide the immune response, but also initiate these events. They are able to present the antigen in the context of MHC class I molecules, and activate naїve CD8+ T lymphocytes. Potential consequences of platelet interaction with neutrophils, monocytes, dendritic cells and lymphocytes are discussed in the review article

IL-2 and regulation of stress hormones and BDNF neurotropic factor levels after experimental traumatic brain injury (TBI)

Experimental traumatic brain  injury  (TBI)   causes  a  stable  stress  response   and  changes   the expression  of various cytokine genes and neurotrophic factors.  The goal of this study was to reveal changes  in the  levels of the  corticosterone and  testosterone hormones and  the  BDNF cytokine in blood  serum,  as well as the expression  of the BDNF gene in hypothalamus in order  to determine the opportunity of correcting the TBI damage  with rIL-2. We used a rat model  of “dropping load”:  mild TBI was caused  by falling of the 115 g load from the height  of 80 cm,  or 120 cm to produce a moderate-degree trauma. After TBI (immediately, or 72 hours  later), the  rats were injected daily with recombinant human interleukin-2 (Roncoleukin) at a dose of 30 μg/kg, a total  of 3 injections. Control animals  (also with TBI)  received  0.15 M NaCl  injections. Blood serum  concentrations of corticosterone, testosterone, and  BDNF were measured with ELISA  tests.  BDNF gene expression in hypothalamus was measured using RT-PCR. Results: the experiments showed a relationship between  hormone concentrations and severity of head injury. In mild TBI,  blood corticosterone levels reached a peak  2 hours  after the  injury, while in moderate TBI,  the  peak  concentration of corticosterone was lower, being delayed  in time  (after  24 hours). Corticosterone and  testosterone concentrations changed reciprocally in the both groups of injured  animals. With injection of rIL-2 in both groups,  corticosterone and testosterone levels were significantly  increased. On  day 7 after  TBI,  the  BDNF level in blood  serum  was decreased, but it was raised  in experimental group  that  received  rIL-2. On day 7, the increase  of BDNF gene expression  in hypothalamus was more  pronounced, when  rIL-2 was administered at 72 hours  after  the  head  injury.  The revealed  positive  association of BDNF levels and  glucocorticoid hormones after  mild  TBI,  like as possible coordination of these  parameters with rIL-2 injection after experimental moderate TBI  provides  a reason  to assume  that  the favorable  impact of rIL-2 on the CNS  recovery  after TBI is, in part,  mediated by the mutual modulating interaction of BDNF and glucocorticoid hormones

BLOOD PLATELETS AS ACTIVATORS AND REGULATORS OF INFLAMMATORY AND IMMUNE REACTIONS. PART 1. BASIC CHARACTERISTICS OF PLATELETS AS INFLAMMATORY CELLS

Platelets are the smallest blood cells, and yet their total volume and surface area exceed those of all types of leukocytes combined. Platelets are produced by the bone marrow megakaryocytes and megakaryocytes in the lung microvessels. Approximately 50% of all platelets are produced in the lungs, which makes it possible to characterize them as the main site for the production of platelets. In small circuit of blood circulation, there are approximately 30% more platelets than in large circuit. This “excess” of platelets is necessary for the stabilization of the endothelial barrier of the lung vessels regulated by the platelet mediator sphingosine-1-phosphate, a regulator of tight junctions of endothelial cells. The circulating platelets have an amazing ability to “bud” new pro- and pre-platelets, giving rise to new platelets. The removal of platelets from circulation proceeds via their phagocytosis by spleen macrophages (if platelets are covered with IgG or are bound to immune complexes), or Kupffer liver cells and hepatocytes (if platelets have incomplete glycans or desialated proteins). In homeostatic conditions, most of the platelets are removed in liver. Platelet clearance in bacterial infections and sepsis is accelerated because of the activity of bacterial sialidases. Recognition of desialized platelet structures is carried out by the liver cells through the Asgr receptor. Despite DNA absence, the platelets are able to synthesize proteins at mRNAs that are present in majority of platelets. Activation of platelets leads to aggregation and exocytosis of the granule contents, and production of immunomodulating molecules. However, activation of platelets may be incomplete and has various consequences. In a non-classical activation model, platelets can release microparticles that contain about 600 different proteins. About 75% of microparticles in the blood of healthy donors are derived from platelets. Like as immune system cells, platelets are activated by numerous endogenous ligands (alarms), including ADP and ATP, which bind to purinergic receptors P2Y1, P2Y12 andP2X1. Platelets accumulate and retain 99% of the serotonin stored in the body. The platelets contribute to induction of inflammation by releasing proinflammatory cytokines, chemokines, and lipid mediators. In addition, platelets are the source of enzymes that accomplish the capacities of neutrophils and endothelium for production of anti-inflammatory lipid mediators that contribute to tissue repair following acute phase of inflammation

Immunomodulatory and neurotropic activities of synthetic peptides in a model of brain injury in rats

Treatment of consequences of traumatic brain injury (TBI) remains one of the current problems of medicine. To increase the effectiveness of treatment of post-traumatic complications, various drugs are recommended, including the peptide with neuromodulatory activity Semax.The present study aims to determine the presence of neuro- and immunoprotective properties of the synthetic peptide PR5, composed of fragments of proline-rich antimicrobial peptides.The work was performed on male Wistar rats weighing 300-350 g. The “falling weight” model of mechanical brain injury was used, which mainly causes diffuse brain damage. The synthesized peptide PR5, composed of fragments of known proline-rich peptides of animal neutrophils, and the peptide preparation Semax in the form of a 1% aqueous solution were used. The drugs were administered intranasally 1 hour after TBI, then twice a day for 4 days at a dose of 100 mg/kg body weight. Control animals received physiological saline in the same regimen as the peptide preparations.TBI led to a significant decrease in body weight, but in rats receiving the peptide preparation Semax, the decrease in body weight was significantly less than in control animals, and the PR5 preparation completely prevented the decrease in body weight after TBI. After TBI, the proliferative activity of lymphocytes was suppressed and the cytotoxicity of NK cells decreased. In animals treated with peptide preparations, there was no significant suppression of NK cell cytotoxicity, and the proliferative activity of lymphocytes was restored to the level of control animals by day 14 after TBI. Both peptide preparations used contributed to higher locomotor activity, and in animals treated with the PR5 peptide, this type of activity reached the parameters of control animals. The reduction in freezing duration in groups treated with peptide preparations indicates the presence of a sedative effect.The peptide preparation PR5 was active in this series of experiments, showing immunotropic and neuroprotective activity comparable to the Semax preparation. Further studies aimed at confirming the identified types of activity of the peptide preparation PR5 may justify its prospects for clinical use as a new nootropic agent

Changing National Health Values of Russian Youth Aged 13-17: Motivation for Engagement in Physical Culture and Sports in Regions

The article is devoted to the study of the attitudes of contemporary Russian youth to a healthy lifestyle, healthcare in general, and physical culture and sports. As a result of a qualitative sociological study, the main trends and perspectives in the perception of a healthy lifestyle, physical culture, and sports in Russian regions are discovered and defined. The study specifies the motivational aspects of young Russians' attitudes to a healthy lifestyle, healthcare, physical culture, and sports. The specific features of the development of regional physical culture and sports in Russia, as well as the characteristics of the perception of physical culture and sports by various groups of Russian youth in the regions of the country, are identified. The attitudes to social stereotypes concerning a healthy lifestyle and sports in the minds of Russian citizens are discovered. The practical significance of the study results: The conclusions of the project can be used for the development of youth policy, as well as the development of new programs for the optimization of young people's lifestyle and the development of physical culture and sports in Russia. The study results can be utilized for the innovation of courses on the sociology of health and disease, sociology of physical culture and sports, and sociology of medicine. © 2021 Sociedade Portguesa de Estomatologia e Medicina Dentaria. All rights reserved

RESEARCHING OF ADSORPTION PROPERTIES OF COATINGS FOR CORROSION PROTECTION OF REFINERY EQUIPMENT

Corrosion of refinery plants is a serious problem because sulfur compounds contained in oil have a significant impact on the corrosion process. The exploitation of this equipment without special protective measures is unacceptable. The operation of this equipment with the use of protective coatings