Search

The main manifestations of COVID-19 are primarily interstitial pneumonia and respiratory failure. No less than 20% of patients have variable skin rashes, which try to be interpreted as markers and predictors of the peculiarities of the course of coronavirus infection. In addition, hair loss is a characteristic manifestation of COVID-19, and the salivary follicles are regarded as a target for SARS-CoV-2. The most common variants of alopecia in patients with a new coronavirus infection or vaccine-induced alopecia are acute telogenic, nondescript, and androgenetic alopecia. This review provides information on the most common variants of hair loss in patients with SARS-CoV-2 infection, the features of their manifestations, and possible mechanisms of development. Acute telogenic hair loss is the most common variant of SARS-CoV-2-induced alopecia, is characteristic of patients with subacute course of COVID-19 and can be combined with trichodynia, anosmia and aguvia, which are markers of nervous syste damage. Given the variability in the time of onset after infection, a heterogeneous pathogenesis of alopecia can be assumed. Nested alopecia after COVID-19 is often a relapse of the disease, its severity and frequency do not correlate with the severity of the infectious disease, and its prevalence in women indicates the importance of hormonal factors in its development. Androgenetic alopecia may be a predictor of high risk of infection, severe course, and recurrence of COVID-19. The first two variants of alopecia may be associated with COVID-19 vaccination, and the latter is a predictor of inadequate immune response to vaccine administration. The mechanisms of the damaging effects of SARS-CoV-2 on hair follicles have not been fully deciphered and are most likely complex, with different leading links in different types of hair loss. Deciphering these mechanisms may provide prerequisites for understanding the mechanisms of COVID-19 damage to other tissues and organs.

A native potato starch was modififi ed with vinyl acetate by graft polymerization in alkaline medium with pH 10 in the mode of temperature change from 70 to 80°C for 4 hours. The initiator of the process was ammonium persulfate (NH4)2S2O8. The conversion of vinyl acetate was 91,5%. The chemical structure of graft copolymer (Starch:Vinyl acetate) was confifi rmed by IR-spectroscopy. Composite materials of modififi ed starch and triethyl citrate with tensile strength of 24 MPa were obtained. Under natural environmental conditions, materials undergo biodegradation of 96% in 28 days.

The review article is devoted to the history of the discovery of genes that regulate iron metabolism. The natural model that became the basis for the study of genes was hemochromatosis (HC). HC is a hereditary disease caused by excess iron in tissues. The first to be discovered was the HFE gene, whose physiological role is to prevent iron overload in cells by decreasing the binding of transferrin receptor-1 (TFR-1) to metal-saturated transferrin. This happened in 1996; the gene was mapped to chromosome 6p.23.3. In the European population, mutations in the HFE gene were detected in 80-100% of patients with HC. This variant of the disease is classified as type 1 He in OMIM. In 1999, the HJV gene on chromosome 1q21 was discovered, the product of which, hemouvelin, was later found to modulate the expression of hepcidin, and the SLC40A1 gene on chromosome 2q32, which encodes ferroportin, an iron transporter from enterocytes, macrophages, hepatocytes and placental cells into blood plasma. HC associated with mutations in these genes is represented by types 2A and 4 in the OMIM classification. In 2000, the HAMP gene on chromosome 19q13.1 was discovered, encoding the main iron regulatory hormone hepcidin, which blocks ferroportin, and the TFR-2 gene on chromosome 7q22. controlling the capture of iron by hepato-cytes and bone marrow cells, as well as the level of metal in the blood plasma. HC associated with mutations in these genes is represented by types 2B and 3 in the OMIM classification.

The production of new effective hemostatic materials based on a polymer composition of modified chitosan with a three-dimensional cross-linked structure as a polymer matrix and calcium ions coordinated to it is addressed. The optimum concentration of calcium ions in the chitosan-based composition was established as 10 – 20 mM and ensured an effective in vitro blood coagulation time of 40 sec. Compositions of chitosan succinate and chloride in addition to chitosan in solutions with nicotinic acid were shown to have effective hemostatic activity. Statistical differences in the effects of various calcium salts on the blood coagulation time were not found. In vivo tests showed that a chitosan-based composition was effective for stopping bleeding of any degree of severity, both with external and internal injuries to tissues.

Three new organoselenium compounds are synthesized: N-phenyl-2-(2-thienylacetyl)hydrazinecarboselenoamide (I), 4-phenyl-5-(2-thienylmethyl)-2,4-dihydro-3H-1,2,4-triazole-3-selone (II), and 3,3'-di[4-phenyl-5-(2-thienylmethyl)-4H-1,2,4-triazolyl] diselenide (III). Two of them (compounds II and III) are characterized by X-ray diffraction analysis (CIF files CCDC nos. 1956602 (II) and 1956603 (III)). Compound II crystallizes in the monoclinic crystal system (space group P21/n) with two crystallographically independent molecules A and B being different conformers relative to rotation about the NTrz–CTrz–C(H2)–CTph bond, where Trz is triazole and Tph is thiophene (gauche-A (51.4(3)°) and cis-B (4.2(4)°)). In the crystal of compound II, molecules A and B form chains along the crystallographic axis a due to strong hydrogen bonds N–H···Se. Then the chains are bound into a three-dimensional framework via intermolecular nonvalent interactions Se···S (3.3857(11) A). Owing to the anomeric effect, diselenide III is characterized by the typical gauche conformation of the substituents at the Se–Se bond (torsion angle СSeSeС 83.5(4)°) stabilized by a weak intramolecular hydrogen bond С–H···π. In the crystal of compound III, the molecules form chains along the crystallographic acid b due to intermolecular noncovalent interactions Se···π(C–C) (3.404(6) and 3.458(12) A), Se···Se (3.8975(11) A), and S···N (3.250(5) A). Bactericidal and fungicidal activity of the synthesized compounds is studied.

Grafted copolymers of gelatin and polymethyl methacrylate are synthesized using the tributylboron–oxygen initiating system in an aqueous dispersion at 60°C. The products are characterized by IR spectroscopy and gel permeation chromatography. The proportion of polymethyl methacrylate in the copolymer is 2–60% and increases with a higher concentration of alkylborane in the initial mixture. The particle size of the aqueous dispersions of the copolymers determined by dynamic light scattering exceeds the particle size of gelatin. The thermogravimetric curves of the copolymers are similar to those of gelatin, with thermal stability tending to increase with a higher concentration of tributylboron. All the copolymers are biodegradable by fungi.

Thermal analysis of samples of chitosan–poly(methyl acrylate) block copolymer after exposure to electromagnetic fields, ultraviolet radiation, ultrasound, and biodestructive agents is performed for the first time by means of differential scanning calorimetry in the range of 250–510 K and thermogravimetry in the region of 300–850 K. It is shown that the combined effect of physical factors and biodestructive agents alters certain physicochemical properties: the temperatures of physical transformations, the temperatures of the onset of thermal degradation, and the nature of thermal decomposition.

The optically transparent biocompatible, biodegradable, wound-healing materials were obtained based on chitosan and poly(lactide–titanium oxide). The optical transmittance of these films was more than 70% in the visible light region. The decreasing of the films transmittance by ~ 5–10% was observed under its UV irradiation as a result of the one-electron transition Ti4+ + e− ⇄ Ti3+. The tensile strength of the samples was up to 117 MPa. The investigation of the materials biocompatibility on experimental animals demonstrated the positive blood parameters and the absence of the inflammation process in the animals’ organisms, allergic reactions and stress after implantation of film and non-toxicity of the composite. The materials can be bioutilized and are biodegradable. The fibroblast cells (hTERT BY-5ta) adhesion and proliferation on the films surface were demonstrated in vitro. The films exhibited the UV-induced antibacterial properties.

Increasingly, scientists are turning to the study of marine, or fish, collagen, which is increasingly replacing collagen of terrestrial animals, due to the fact that it is hypoallergenic, since it is 96% identical to human protein. Materials based on fish collagen have a number of advantages over their analogue of animal origin: it is not a carrier of infectious diseases of animals transmitted to humans, it has a greater structural similarity to human collagen, which provides a higher level of biocompatibility. Materials based on collagen copolymers with synthetic monomers are promising. The use of hybrid materials also helps to reduce the consumption of non-renewable natural resources. Synthesis of grafted collagen copolymers with polybutyl acrylate was carried out at azobisisobutyronitrile initiation and triethyl borane – oxygen system initiation under comparable conditions under intensive stirring of aqueous solution dispersion of collagen and butyl acrylate. After the synthesis, the aqueous and organic phases of the reaction mixture were analyzed by composition and molecular weight parameters using infrared spectroscopy and size-exclusion chromatography. Changes indicating the formation of a copolymer are observed in the copolymer isolated from the aqueous phase, more pronounced in the triethyl borane – oxygen system. It is assumed that the formation of copolymer macromolecules for azobisisobutyronitrile and organoelement initiator takes place according to different schemes. Schemes for the formation of copolymer macromolecules for AIBN and an organoelement initiator are proposed. Only polybutyl acrylate is present in the organic phase. Biological studies were carried out for fungal resistance and bactericidal activity of the obtained copolymers.

The heat capacity and the temperatures and enthalpies of physical transformations of the alternating terpolymer of carbon monoxide, ethylene, and 1-butene (the content of butene units is 10.7 mol.%) were studied by adiabatic and differential scanning calorimetry in the temperature range from 6 to 520 K. The energy of terpolymer combustion was measured at 298.15 K on an calorimeter with an isothermal shell and static bomb. The standard thermodynamic functions C°p(T), H°(T)–H°(0), S°(T)–S°(0), and G°(T)–H°(0) for the range from Т → 0 to 400 K, the standard enthalpy of combustion, and the thermodynamic parameters of formation of the partially crystalline CO—ethylene—1-butene terpolymer at 298.15 K, as well as the thermodynamic characteristics of its synthesis in the range from T → 0 to 400 K were calculated.

Block and graft copolymers of chitosan with methyl acrylate, 2-ethylhexyl acrylate, 2-hydroxy- ethyl methacrylate, 2-hydroxypropyl methacrylate, and styrene with different spatial orientations of natural and synthetic chains and molecular masses are synthesized. The effects of the structures of the copolymers on the physicomechanical properties of their films and their biodegradability by micromycetes are revealed.

The influence of the molecular mass of chitosan and the thermodynamic quality of the solvent on the dimensional characteristics of silver nanoparticles during their in situ formation via UV reduction of silver ions from the dopant silver nitrate dopant in a chitosan-stabilizing solution is investigated. The possibility to regulate the sizes of silver nanoparticles from 8 to 12 nm via changes in the molecular mass of the stabilizer is shown.

Morphofunctional features of skin mast cells located in the areas subjected to chronic UV-radiation and in the associated basal cell carcinoma with photoinjure have been studied. Various immunohistochemical methods (chromogranin A, CDla, HLA-DR, CD35, Ki67, P53, Bcl-2, Mcl-1, involucrine) were used. It is found that chronic UV-damage leads to mast cell hyperplasia as well as activation of their synthetic, absorption and secretory functions. It is suggested that mast cell hyperplasia and increase of mast cells neuroendocrine activity provide a risk of basal cell carcinoma development.

The spectra of neutrons10 MeV and gamma-rays 1.5-100 MeV under the Earth Radiation Belts, restored from the data, obtained onboard orbital complex "SALYUT-7" [correction of "SALUTE-7"]-"KOSMOS-1686", are presented. The spectra shapes are similar to those for albedo neutrons and gamma-rays, but absolute values of their fluxes (0.2 cm-2 s-1 for neutrons, 0.8 cm-2 s-1 for gamma-rays at the equator and 1.2 cm-2 s-1, 1.9 cm-2 s-1, accordingly, at L=1.9) are several times as large. It is possibly explained by the fact that most of the detected particles were produced by the cosmic ray interactions with the orbital complex matter. Neutron and gamma-ray fluxes obtained from "CORONAS-1" data are near those for albedo particles.

The results of experience in the comparative evaluation of the preseasonal immunoglobulin prophylaxis in two towns of the Gorki Province are presented. The work substantiates the economic and epidemiological effectiveness of immunoglobulin prophylaxis at the territory, relatively safe with respect to hepatitis A, under the conditions of its realization in the year of the predicted rise of morbidity, the timely organization of immunoglobulin prophylaxis (from July to the first half of October) and the coverage of "organized" children, exceeding 90%.

On the basis of studies performed, an adequate kinetic model of the polymer solution process has been constructed, which takes account of degradation. An estimate of the coefficients of the model has been made from experimental data.

Nowadays various information documents on toxicity and danger of chemical substances exist, i. e., toxicologic certificates, data profiles, trade certificates, etc. An attempt has been made to analyze 15 available data lists used in various countries for the description of noxious and hazardous characteristics of chemicals. The indices on toxicity and danger of chemicals enumerated in the lists are grouped by 9 main categories. The degree of detailed description of the data presented is determined by the aim of the document. The results thus obtained can be used in the further work aimed at the improvement and unification of the forms providing the data on toxicity and danger of the chemicals.