523 results match your criteria: "V N. Karazin Kharkiv National University[Affiliation]"

The high mutation rate of SARS-CoV-2, which has led to the emergence of a number of virus variants, creates risks of transmission from humans to animal species and the emergence of new animal reservoirs of COVID-19. This study aimed to identify animal species among livestock susceptible to infection and develop an approach that would be possible to use for assessing the hazards caused by new SARS-CoV-2 variants for animals. Bioinformatic analysis was used to evaluate the ability of receptor-binding domains (RBDs) of different SARS-CoV-2 variants to interact with ACE2 receptors of livestock species.

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Protonation of key histidine residues has been long implicated in the acid-mediated cellular action of the diphtheria toxin translocation (T-) domain, responsible for the delivery of the catalytic domain into the cell. Here, we use a combination of computational (constant-pH Molecular Dynamics simulations) and experimental (NMR, circular dichroism, and fluorescence spectroscopy along with the X-ray crystallography) approaches to characterize the initial stages of conformational change happening in solution in the wild-type T-domain and in the H223Q/H257Q double mutant. This replacement suppresses the acid-induced transition, resulting in the retention of a more stable protein structure in solutions at pH 5.

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Despite previous studies, understanding the fundamental mechanism of melting metal nanoparticles remains one of the major scientific challenges of nanoscience. Herein, the kinetics of melting of a single Sn nanoparticle was investigated using transmission electron microscopy heating techniques with a temperature step of up to 0.5 °C.

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Background: Herein, we describe a new species of turtle blood-feeding leech, Placobdella nabeulensis sp. nov. from Palearctic North Africa (Tunisia and Algeria).

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Tuberculosis: current challenges and beyond.

Breathe (Sheff)

March 2023

Centre for Multidisciplinary Research in Health Science, University of Milan, Milan, Italy.

Despite being a preventable and curable disease, tuberculosis (TB) is still a major global health threat and the second leading cause of death due to an infectious agent worldwide. All the efforts invested to end TB have resulted overall in rather slow decreases in TB incidence and mortality rates, which have been further negatively affected by the ongoing coronavirus disease 2019 (COVID-19) pandemic. While the majority of targets of the End TB Strategy remain off track, and we have not yet overcome the disruptions caused by the COVID-19 pandemic, recent conflicts such as the ongoing war in Ukraine are threatening the decrease of the burden of TB even further.

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We explore the rich nature of correlations in the ground state of ultracold atoms trapped in state-dependent optical lattices. In particular, we consider interacting fermionic ytterbium or strontium atoms, realizing a two-orbital Hubbard model with two spin components. We analyze the model in one-dimensional setting with the experimentally relevant hierarchy of tunneling and interaction amplitudes by means of exact diagonalization and matrix product states approaches, and study the correlation functions in density, spin, and orbital sectors as functions of variable densities of atoms in the ground and metastable excited states.

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Objective: The aim: To clarify the frequency with which various variants of the formation and course of drug-resistant epilepsy occur in children with genetic polymor¬phisms of cytochromes CYP2C9, CYP2C19, CYP3A4.

Patients And Methods: Materials and methods: The genotyping of CYP2C9*2, CYP2C9*3, CYP2C19*2, CYP3A4*1B by the allele-specific polymerase chain reaction was performed in 116 children with drug-resistant epilepsy aged from 2 to 17 years. Thirty cases (boys-15; girls-15) with a follow-up period of more than 5 years were analyzed in detail.

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Objective: The aim: To estimate the role of macrophage migration inhibitory factor and soluble ST2 in predicting the left ventricle remodeling six months after ST-segment elevation myocardial infarction.

Patients And Methods: Materials and methods: The study involved 134 ST-segment elevation myocardial infarction patients. Occurrence of post-percutaneous coronary (PCI) intervention epicardial blood flow of TIMI <3 or myocardial blush grade 0-1 along with ST resolution <70% within 2 hours after PCI was qualified as the no-reflow condition.

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Polymorphism of 6-methyluracil, which affects the regulation of lipid peroxidation and wound healing, has been studied by experimental and quantum chemical methods. Two known polymorphic modifications and two new crystalline forms were crystallized and characterized by single crystal and powder X-ray diffraction (XRD) methods as well as by the differential scanning calorimetry (DSC) method and infrared (IR) spectroscopy. The calculations of pairwise interaction energies between molecules and lattice energies in periodic boundary conditions have shown that the polymorphic form used in the pharmaceutical industry and two new forms and , which can be formed due to temperature violations, may be considered as metastable.

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The end products of catabolism of tryptophan (Trp), an essential amino acid, are known to affect mechanism(s) of aging, a neurodegenerative condition. This review focuses on the possible role of the initial step of Trp catabolism, kynurenine (Kyn) formation from Trp, in aging mechanism(s). Rate-limiting enzymes of Trp conversion into Kyn are tryptophan 2,3-dioxygenase 2 (TDO) or indoleamine 2,3-dioxygenase (IDO).

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The relationships between the structural and aggregational state of bovine serum albumin (BSA) and the specific length and total number of zigzag pattern segments of the film textures formed upon drying biopolymer solutions with aluminum and iron chlorides have been shown. To obtain films, saline solutions of BSA were dried in a glass cuvette under thermostatically controlled conditions. It is shown that the formation of zigzag structures is sensitive to the influence of aluminum chlorides Al and iron chlorides Fe and depend on the concentration of AlCl and FeCl.

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Peptidomimetics with a substituted imidazo[1,2-]pyridine fragment were synthesized by a tandem of Groebke-Blackburn-Bienaymé and Ugi reactions. The target products contain substituted imidazo[1,2-]pyridine and peptidomimetic moieties as pharmacophores with four diversity points introduced from readily available starting materials, including scaffold diversity. A small focused compound library of 20 Ugi products was prepared and screened for antibacterial activity.

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Objective: Uterine sarcomas are a rare and heterogeneous group of malignancies that include different histological sub-types. The aim of this study was to identify and evaluate the impact of the different prognostic factors on overall survival and disease-free survival of patients with uterine sarcoma.

Methods: This international multicenter retrospective study included 683 patients diagnosed with uterine sarcoma at 46 different institutions between January 2001 and December 2007.

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The molecular docking calculations have been employed to investigate the interactions a set of proteins with the repurposed anti-COVID drugs. The position of the therapeutic agents within the protein structure was dependent on a particular drug-protein system and varied from the binding cleft to the periphery of the polypeptide chain. Interactions involved in the drug-protein complexation includes predominantly hydrogen bonding and hydrophobic contacts.

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A sample of 351 adults (women/men 4:1) aged 18 to 60 participated in an online survey administered during the first two waves (15 March-25 April and 10 October-25 November 2020) of the COVID-19 pandemic in Ukraine. The user ethnography profile was Generation Z (born in the 1990s), female (81.2%), Instagrammer (60.

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Fӧrster resonance energy transfer analysis of amyloid state of proteins.

BBA Adv

October 2022

Department of Medical Physics and Biomedical Nanotechnologies, V. N. Karazin Kharkiv National University, 4 Svobody Sq., Kharkiv 61022, Ukraine.

The Förster resonance energy transfer (FRET) is a well-established and versatile spectroscopic technique extensively used for exploring a variety of biomolecular interactions and processes. The present review is intended to cover the main results of our FRET studies focused on amyloid fibrils, a particular type of disease-associated protein aggregates. Based on the examples of several fibril-forming proteins including insulin, lysozyme and amyloidogenic variants of N-terminal fragment of apolipoprotein A-I, it was demonstrated that: (i) the two- and three-step FRET with the classical amyloid marker Thioflavin T as an input donor has a high amyloid-sensing potential and can be used to refine the amyloid detection assays; (ii) the intermolecular time-resolved and single-molecule pulse interleaved excitation FRET can give quantitative information on the nucleation of amyloid fibrils; (iii) FRET between the membrane fluorescent probes and protein-associated intrinsic or extrinsic fluorophores is suitable for monitoring the membrane binding of fibrillar proteins, exploring their location relative to lipid-water interface and restructuring on a lipid matrix; (iv) the FRET-based distance estimation between fibril-bound donor and acceptor fluorophores can serve as one of the verification criteria upon structural modeling of amyloid fibrils.

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Permeabilization of the mitochondrial outer membrane-a point of no return in apoptotic regulation-is tightly controlled by proteins of the Bcl-2 family. Apoptotic inhibitor Bcl-xL is an important member of this family, responsible for blocking the permeabilization, and is also a promising target for anti-cancer drugs. Bcl-xL exists in the following conformations, each believed to play a role in the inhibition of apoptosis: (i) a soluble folded conformation, (ii) a membrane-anchored (by its C-terminal α8 helix) form, which retains the same fold as in solution and (iii) refolded membrane-inserted conformations, for which no structural data are available.

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Bioinformatic analysis of mutation sets in receptor-binding domain (RBD) of currently and previously circulating SARS-CoV-2 variants of concern (VOCs) and interest (VOIs) to assess their ability to bind the ACE2 receptor. sequence and structure-oriented approaches were used to evaluate the impact of single and multiple mutations. Mutations detected in VOCs and VOIs led to the reduction of binding free energy of the RBD-ACE2 complex, forming additional chemical bonds with ACE2, and to an increase of RBD-ACE2 complex stability.

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Majorana's approach to nonadiabatic transitions validates the adiabatic-impulse approximation.

Sci Rep

March 2023

Theoretical Quantum Physics Laboratory, Cluster for Pioneering Research, RIKEN, Wakoshi, Saitama, 351-0198, Japan.

The approach by Ettore Majorana for non-adiabatic transitions between two quasi-crossing levels is revisited and significantly extended. We rederive the transition probability, known as the Landau-Zener-Stückelberg-Majorana formula, and introduce Majorana's approach to modern readers. This result, typically referred as the Landau-Zener formula, was published by Majorana before Landau, Zener and Stückelberg.

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Dried rhizomes have been used in Chinese and European traditional medicine for the treatment of various diseases such as bacterial infections, cancer, and inflammation, as well as for being astringent, laxative, and diuretic agents. Eighteen phenolic compounds including some rare secondary metabolites, such as irisolidone, kikkalidone, irigenin, irisolone, germanaism B, kaempferol, and xanthone mangiferin, were isolated for the first time from rhizomes. The hydroethanolic extract and some of its isolated constituents showed protective effects against influenza H1N1 and enterovirus D68 and anti-inflammatory activity in human neutrophils.

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The title compound, CHNOF, can be obtained a two-step synthetic scheme involving 1-benzyl-6-fluoro-4-oxo-7-(piperidin-1-yl)-1,4-di-hydro-quino-line-3-carbo-nitrile as a starting compound that undergoes substitution with hydroxyl-amine and subsequent cyclization with 4-methyl-cyclo-hexane-1-carb-oxy-lic acid. It crystallizes from 2-propanol in the triclinic space group with a mol-ecule of the title compound and one of 2-propanol in the asymmetric unit. After the mol-ecular structure was clarified using NMR and LC/MS, the mol-ecular and crystalline arrangements were defined with SC-XRD.

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While the physicochemical properties as well as the NMR and vibration spectroscopic data of the mixtures of ionic liquids (ILs) with molecular solvents undergo a drastic change around the IL mole fraction of 0.2, the local structure of the mixtures pertaining to this behavior remains unclear. In this work, the local structure of 12 mixtures of 1-butyl-3-methylimidazolium cation (Cmim) combined with perfluorinated anions, such as tetrafluoroborate (BF), hexafluorophosphate (PF), trifluoromethylsulfonate (TFO), and bis(trifluoromethanesulfonyl)imide, (TFSI), and aprotic dipolar solvents, such as acetonitrile (AN), propylene carbonate (PC), and gamma butyrolactone (γ-BL) is studied by molecular dynamics simulations in the entire composition range, with an emphasis on the IL mole fractions around 0.

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The energy and velocity distributions of ideal gas particles were first obtained by Boltzmann and Maxwell in the second half of the nineteenth century. In the case of a finite number of particles, the particle energy distribution was obtained by Boltzmann in 1868. However, it appears that this distribution is not valid for all vessels.

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Modern technologies stimulate the quest for multicomponent nanosized materials with improved properties, which are ultimately defined by the atomic arrangement and interphase interactions in the nanomaterial. Here, we present the results of the experimental study of the formation of solid solutions in Ag-Cu nanoparticles in a wide size and temperature range using TEM techniques. The Ag-Cu nanoparticles with a eutectic ratio of components were formed on an amorphous carbon film by the physical vapor deposition technique.

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The trinuclear high-spin iron(III) complex [FeCl(saltag)(py)]ClO {Hsaltag = 1,2,3-tris[(5-bromo-salicylidene)amino]guanidine} was synthesized and characterized by several experimental and theoretical methods. The iron(III) complex exhibits molecular 3-fold symmetry imposed by the rigid ligand backbone and crystallizes in trigonal space group 3̅ with the complex cation lying on a crystallographic axis. The high-spin states ( = /) of the individual iron(III) ions were determined by Mößbauer spectroscopy and confirmed by CASSCF/CASPT2 ab initio calculations.

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