General dynamics of the URT microbiome and microbial signs of recovery in COVID-19 patients.

COVID-19 is caused by an airborne virus, SARS-CoV-2. The upper respiratory tract (URT) is, therefore, the first system to endure the attack. Inhabited by an assemblage of microbial communities, a healthy URT wards off the invasion. However, once invaded, it becomes destabilised, which could be crucial to the establishment and progression of the infection. We examined 696 URT samples collected from 285 COVID-19 patients at three time-points throughout their hospital stay and 100 URT samples from 100 healthy controls. We used 16S ribosomal RNA sequencing to evaluate the abundance of various bacterial taxa, α-diversity, and ß-diversity of the URT microbiome. Ordinary least squares regression was used to establish associations between the variables, with age, sex, and antibiotics as covariates. The URT microbiome in the COVID-19 patients was distinctively different from that of healthy controls. In COVID-19 patients, the abundance of 16 genera was significantly reduced. A total of 47 genera were specific to patients, whereas only 2 were unique to controls. The URT samples collected at admission differed more from the control than from the samples collected at later stages of treatment. The following four genera originally depleted in the patients grew significantly by the end of treatment: Fusobacterium, Haemophilus, Neisseria, and Stenotrophomonas. Our findings strongly suggest that SARS-CoV-2 caused significant changes in the URT microbiome, including the emergence of numerous atypical taxa. These findings may indicate increased instability of the URT microbiome in COVID-19 patients. In the course of the treatment, the microbial composition of the URT of COVID-19 patients tended toward that of controls. These microbial changes may be interpreted as markers of recovery.

Taxonomic and ecophysiological characteristics of actinobacteria in soils of the dry steppe zone of the Selenga Highlands (Western Transbaikalia).

Arid habitats have recently attracted increasing attention in terms of biodiversity research and the discovery of new bacterial species. These habitats are among the target ecosystems suitable for isolating new strains of actinobacteria that are likely to produce new metabolites. This paper presents the results on the isolation of actinobacteria from soils of the dry steppe zone of the Selenga Highlands, the characterization of their taxonomic diversity, as well as ecological and trophic properties. The bacterial counts on ISP 4 medium ranged from 6.6 × 105 to 7.1 × 106 CFU/g. The highest bacterial counts were observed in the subsurface and middle horizons of the studied soils. 28 strains of Gram-positive bacteria represented by thin-branched mycelium, coccoid and bacilliform forms were isolated. According to the results of 16S rRNA gene analysis, the isolated strains were representatives of Streptomyces, Arthrobacter, Glycomyces, Kocuria, Microbacterium, Micromonospora, Nocardioides, Pseudarthrobacter, and Rhodococcus (Actinomycetota). One isolate that showed low 16S rRNA gene sequence similarity with previously isolated and validly described species was a new species of the genus Glycomyces. It was shown that all tested strains are mesophilic, prefer neutral or slightly alkaline conditions, have growth limits in the temperature range of 5-45 °C and pH 6-9. The optimal NaCl concentration for growth of most strains was 0-1 %. The strains under study were capable of utilizing a wide range of mono- and disaccharides and polyatomic alcohols as a carbon source. The isolated strains were capable of using both organic (proteins and amino acids) and inorganic (ammonium salts and nitrates) compounds as nitrogen sources. The examinations of extracellular enzymes showed that all isolates were capable of producing catalase and amylase; 78.6 % of the total number of isolates produced protease and lipase; 53.6 %, cellulase; and 28.6 %, urease. The data obtained expand current knowledge about the diversity of microbial communities in soils of the Selenga Highlands and also confirm the potential of searching for new actinobacteria species in these soils.

LIM-kinase 1 effects on memory abilities and male courtship song in Drosophila depend on the neuronal type.

The signal pathway of actin remodeling, including LIM-kinase 1 (LIMK1) and its substrate cofilin, regulates multiple processes in neurons of vertebrates and invertebrates. Drosophila melanogaster is widely used as a model object for studying mechanisms of memory formation, storage, retrieval and forgetting. Previously, active forgetting in Drosophila was investigated in the standard Pavlovian olfactory conditioning paradigm. The role of specific dopaminergic neurons (DAN) and components of the actin remodeling pathway in different forms of forgetting was shown. In our research, we investigated the role of LIMK1 in Drosophila memory and forgetting in the conditioned courtship suppression paradigm (CCSP). In the Drosophila brain, LIMK1 and p-cofilin levels appeared to be low in specific neuropil structures, including the mushroom body (MB) lobes and the central complex. At the same time, LIMK1 was observed in cell bodies, such as DAN clusters regulating memory formation in CCSP. We applied GAL4 × UAS binary system to induce limk1 RNA interference in different types of neurons. The hybrid strain with limk1 interference in MB lobes and glia showed an increase in 3-h short-term memory (STM), without significant effects on long-term memory. limk1 interference in cholinergic neurons (CHN) impaired STM, while its interference in DAN and serotoninergic neurons (SRN) also dramatically impaired the flies' learning ability. By contrast, limk1 interference in fruitless neurons (FRN) resulted in increased 15-60 min STM, indicating a possible LIMK1 role in active forgetting. Males with limk1 interference in CHN and FRN also showed the opposite trends of courtship song parameters changes. Thus, LIMK1 effects on the Drosophila male memory and courtship song appeared to depend on the neuronal type or brain structure.

Bioavailability and Safety of Dihydroquercetin (Review).

Dihydroquercetin (DHQ) is a bioflavonoid with high antioxidant, capillary-protective, and anti-inflammatory activity. DHQ has previously been used for treating Middle East respiratory syndrome coronavirus (MERS-CoV) infection and is currently considered a potential regulator of oxidative stress as part of COVID-19 multipurpose therapy. DHQ has a high safety profile but low bioavailability that limits its use. Innovative techniques (liposomization, crystal engineering, etc.) can be used to increase its bioavailability.

Use of the AFX Stent Graft in Patients with Extremely Narrow Aortic Bifurcation: A Multicenter Retrospective Study.

INTRODUCTION: This study analyzed the patient outcomes following endovascular aortic aneurysm repair (EVAR) for infrarenal aortic pathologies with very narrow aortic bifurcations using the AFX stent graft. METHODS: The data was retrieved from the archived medical records of 35 patients treated for abdominal aortic aneurysm (AAA) (48.6%) or penetrating aortic ulcer (PAU) (51.4%) with very narrow aortic bifurcation between January 2013 and May 2020. Patient survival, freedom from endoleak (EL), and limb occlusion were estimated applying the Kaplan-Meier method. RESULTS: The mean follow-up time was 20.4 ± 22.8 months. The mean aortic bifurcation diameter was 15.8 ± 2.2 mm. Technical success was 100%, and no procedure-related deaths occurred. Two type II ELs occurred within 30-day follow-up. We observed one common iliac artery stenosis at four months and one type III EL at 54 months in the same patient, both of which required re-intervention. Overall patient survival was 95 ± 5% (AAA: 100%; PAU: 89 ± 10%), freedom from limb occlusion was 94 ± 5% (AAA: 91 ± 9%; PAU: 100%), freedom from type II EL was 94 ± 4% (AAA: 88 ± 8%; PAU: 100%), and freedom from EL type III was 83 ± 15% (AAA: 80 ± 18%; PAU: 100%) at the end of the follow-up period. CONCLUSIONS: Very narrow aortic bifurcations may predispose patients to procedure-related complications following EVAR. Our results suggest a safe use of the AFX stent graft in such scenarios. The overall short- and long-term procedure-related patient outcomes are satisfying albeit they may seem superior for PAU when compared to AAA.

Parent-of-origin effects on nuclear chromatin organization and behavior in a Drosophila model for Williams-Beuren Syndrome.

Prognosis of neuropsychiatric disorders in progeny requires consideration of individual (1) parent-of-origin effects (POEs) relying on (2) the nerve cell nuclear 3D chromatin architecture and (3) impact of parent-specific miRNAs. Additionally, the shaping of cognitive phenotypes in parents depends on both learning acquisition and forgetting, or memory erasure. These processes are independent and controlled by different signal cascades: the first is cAMPdependent, the second relies on actin remodeling by small GTPase Rac1 - LIMK1 (LIM-kinase 1). Simple experimental model systems such as Drosophila help probe the causes and consequences leading to human neurocognitive pathologies. Recently, we have developed a Drosophila model for Williams-Beuren Syndrome (WBS): a mutant agnts3 of the agnostic locus (X:11AB) harboring the dlimk1 gene. The agnts3 mutation drastically increases the frequency of ectopic contacts (FEC) in specific regions of intercalary heterochromatin, suppresses learning/memory and affects locomotion. As is shown in this study, the polytene X chromosome bands in reciprocal hybrids between agnts3 and the wild type strain Berlin are heterogeneous in modes of FEC regulation depending either on maternal or paternal gene origin. Bioinformatic analysis reveals that FEC between X:11AB and the other X chromosome bands correlates with the occurrence of short (~30 bp) identical DNA fragments partly homologous to Drosophila 372-bp satellite DNA repeat. Although learning acquisition in a conditioned courtship suppression paradigm is similar in hybrids, the middle-term memory formation shows patroclinic inheritance. Seemingly, this depends on changes in miR-974 expression. Several parameters of locomotion demonstrate heterosis. Our data indicate that the agnts3 locus is capable of trans-regulating gene activity via POEs on the chromatin nuclear organization, thereby affecting behavior.

Hsp70 affects memory formation and behaviorally relevant gene expression in Drosophila melanogaster.

Heat shock proteins, in particular Hsp70, play a central role in proteostasis in eukaryotic cells. Due to its chaperone properties, Hsp70 is involved in various processes after stress and under normal physiological conditions. In contrast to mammals and many Diptera species, inducible members of the Hsp70 family in Drosophila are constitutively synthesized at a low level and undergo dramatic induction after temperature elevation or other forms of stress. In the courtship suppression paradigm used in this study, Drosophila males that have been repeatedly rejected by mated females during courtship are less likely than naive males to court other females. Although numerous genes with known function were identified to play important roles in long-term memory, there is, to the best of our knowledge, no direct evidence implicating Hsp70 in this process. To elucidate a possible role of Hsp70 in memory formation, we used D. melanogaster strains containing different hsp70 copy numbers, including strains carrying a deletion of all six hsp70 genes. Our investigations exploring the memory of courtship rejection paradigm demonstrated that a low constitutive level of Hsp70 is apparently required for learning and the formation of short and long-term memories in males. The performed transcriptomic studies demonstrate that males with different hsp70 copy numbers differ significantly in the expression of a few definite groups of genes involved in mating, reproduction, and immunity in response to rejection. Specifically, our analysis reveals several major pathways that depend on the presence of hsp70 in the genome and participate in memory formation and consolidation, including the cAMP signaling cascade.

[To the study of the corpse tissues' impedance dynamics in the late postmortem period]. / K izucheniyu dinamiki impedansa tkanei trupa v pozdnem posmertnom periode.

The purpose of this work is to establish the dynamics of the electrical conductivity of various corpse tissues using impedance measurements to assess this method for diagnosing the time of death. It was studied the values of the tissue impedance from the corpses of 8 persons of both sexes and different ages (30-50 years) who died from various causes, with the known date of death. A Keysight U1731 parting was used with two probes, which are stainless steel needles with a diameter of 0.5 mm and a 5 mm immersion length. The analysis of special literature on using indicators of the electrical conductivity dynamics of the corpse tissues, determined by the method of impedance measurement, in the early and late postmortem periods to diagnose the time of death. Trial measurements of a methodological nature were carried out with diagnostic zones: skin, cartilage tissue and tendon. The impedance-metric approach is promising for the purposes of forensic medical diagnostics of the time of death; however, it requires more careful experimental work to establish the dynamics of changes in the total electrical resistance of various tissues of a whole corpse over a long period from the moment of death.

Thiacalixarene based quaternary ammonium salts as promising antibacterial agents.

The search for new antibacterial and antiseptic drugs is an urgent problem due to the resistance of microorganisms to existing drugs. In this work, for the first time, the design of antibacterial and bactericidal agents based on quaternary ammonium compounds on thiacalixarene macrocyclic platform was proposed and implemented. A series of tetrasubstituted quaternary ammonium salts with different nature and length of the substituent (-N+(CH3)2R, R = CH2Ph, CnH2n+1, n = 1, 4, 8, 10) based on p-tert-butylthiacalix[4]arene in cone and 1,3-alternate conformations was obtained with excellent yields. The obtained compounds have a high antibacterial effect against Gram-positive (S. aureus, S. epidermidis, B. subtilis) bacteria comparable with commercial antiseptics chlorhexidine, miramistin and benzalkonium chloride. It was found that quaternary ammonium derivatives of thiacalix[4]arene in 1,3-alternate conformation more effectively inhibit the growth of the tested bacterial strains in comparison with compounds in cone conformation. Cytotoxicity studies on human skin fibroblast (HSF) cells demonstrated that all compounds were less toxic compared to reference drugs. The different type of interaction of the studied compounds with model DPPC lipid membranes explains different antibacterial activity and cytotoxicity of compounds. The compounds in cone conformation are adsorbed on the DPPC vesicles membrane surface, while the incorporation of lipophilic alkyl fragments of macrocycles in 1,3-alternate conformation into the membrane leads to "clumping" of DPPC vesicles. It was shown the saving of antibacterial activity of thiacalixarene derivatives in 1,3-alternate conformation on Gram-positive clinical strains. The obtained results allow viewing the described thiacalixarene based quaternary ammonium compounds as promising molecules in the development of the new antibacterial agents.

Silicon-hydroxyapatite‒glycerohydrogel as a promising biomaterial for dental applications.

Nanocomposite silicon-hydroxyapatite‒glycerohydrogel (Si-HA‒glycerohydrogel) with different hydroxyapatite (HA) contents of 0.75 and 1.75 wt.% and the same Si content (2.04 wt.%) was obtained by the sol‒gel method. Silicon tetraglycerolate in the form of glycerol solution was used as a biocompatible precursor and HА in the form of aqueous colloidal suspension - as a template and property modifier. Transmission electron microscopy was applied to demonstrate that there are nanoscale HA particles that are in the crystalline state. For the first time, using the atomic force microscopy method, the remineralizing properties of Si-HA‒glycerohydrogel were studied on human teeth extracted for orthodontic reasons. It was found that Si-HA‒glycerohydrogel containing 1.75 wt.% HA has a pronounced remineralizing effect. Immersion of tooth enamel samples in the gel for one month significantly reduces roughness and makes the enamel surface more uniform. Silicon contained in glycerolates in a biologically active and accessible form exerts an additional positive effect on the process of remineralization of tooth enamel. By the energy dispersive X-ray analysis, it was demonstrated that the tooth enamel had an increased silicon content; and the Vickers microhardness test showed greater microhardness values. The obtained data analysis allows the remineralizing Si-HA‒glycerohydrogel to be considered as a promising biomaterial for dental applications.

The Effects of Weak Static Magnetic Field on the Development of Organotypic Tissue Culture in Rats.

The effects of weak static magnetic field on the organotypic tissue culture of the rat cerebral cortex, liver, and spleen have been investigated. Exposure to a 200 µT static magnetic field induces tissue development, leading to the intensification of regeneration processes compared to the control explants.

[Effect of tryptophan and kynurenine on the cellular proliferation in the organotypic tissue culture of brain cortex in young and old rats.]

Metabolic disorders of L-kinurenin, which is an intermediate product of the breakdown of genetically encoded amino acid L-tryptophan, is one of the links in the development of a number of neuropathological processes. The influence of tryptophan and kynurenine on cell proliferation in organotypic tissue culture of the cerebral cortex in young and old rats was studied. Tryptophan in effective concentration (0,5 ng/ml) inhibited cellular proliferation of the cerebral cortex of young and old rats by 35 and 18%, respectively. However, under the action of kinurenin (1 ng/ml), stimulation of cell proliferation occurred, and more pronounced in the explants of the cerebral cortex of old rats-by 22% compared to the control. The data obtained about the ability of kynurenine to stimulate cellular proliferation in the cerebral cortex of old animals has the potential to create new drugs of nootropic drugs for diseases of the nervous system associated with age.

Comment on "An unexpected formation of the novel 7-oxa-2-azabicyclo[2.2.1]hept-5-ene skeleton during the reaction of furfurylamine with maleimides and their bioprospection using a zebrafish embryo model" by C. E. Puerto Galvis and V. V. Kouznetsov, Org. Biomol. Chem., 2013, 11, 407.

It has been proved that the reaction between furfuryl amines and N-R-maleimides leads to the formation of aza-Michael addition products - 3-(furylmethylamino)-N-R-pyrrolidine-2,5-diones, instead of 7-oxa-2-azabicyclo[2.2.1]hept-5-enes, as this journal reported previously.

Comprehensive meta-analytical summary on human papillomavirus association with head and neck cancer.

An etiological role of high risk human papillomavirus (HPV) in the development of cervical cancer has been well established. Hence, attention of researchers has been focused on the role of HPV in pathogenesis of other malignancies, such as head and neck cancers. An analysis of epidemiological data on the prevalence of HPV infection among healthy people and patients with precancerous lesions and/or cancer is an important step in understanding the role of HPV in head and neck carcinogenesis. More and more data de-monstrate the impact of HPV infection on disease outcome. HPV-positive patients have been shown to have better responses to radiotherapy and better overall and disease-free survival than HPV-negative patients. This review presents data of the meta-analysis based on a large number of original studies on HPV prevalence in patients with precancerous lesions and in patients with oral, oropharyngeal and laryngeal cancers as well as findings on the impact of HPV infection on survival of these patients.

Genetic aspects of HPV infection detection in tumor and adjacent tissues of patients with laryngeal squamous cell carcinoma.

The article describes methods for the human papillomavirus (HPV) detection in tumor and adjacent (morphologically intact) tissues of patients with laryngeal squamous cell carcinoma (LSSC) in terms of viral pathogenesis. Comparative evaluation of the principles and techniques for HPV detection was performed. Advantages and disadvantages of the HPV detection methods are described. Approaches for DNA and HPV oncoproteins E6-E7 identification are substantiated. The results of our research into the qualitative and quantitative detection of HPV in the tumor and adjacent tissues of patients with Lssc are described. The research was conducted using commercial test systems Amplisens HPV HR screen-titre-FL and Amplisens HPV HR genotype-FL. Based on these results we developed the algorithm of HPV detection in samples of tumor tissue of patients with Lssc. The need for typing HPV-positive tissue samples with low concentration of HPV DNA was discussed.

Super-radiant mode in InAs-monolayer-based Bragg structures.

We report direct experimental evidence of the collective super-radiant mode in Bragg structure containing 60 InAs monolayer-based quantum wells (QWs) periodically arranged in GaAs matrix. Time-resolved photoluminescence measurements reveal an appearance of the additional super-radiant mode, originated from coherent collective interaction of QWs. This mode demonstrates a super-linear dependence of the intensity and radiative decay rate on the excitation power. The super-radiant mode is not manifested in the case if only a small number of QWs is excited.

[Influence of limk1 Gene Polymorphism on Learning Acquisition and Memory Formation with pCREB Distribution and Aggregate Formation in Neuromuscular Junctions in Drosophila melanogaster].

We have shown previously that the polymorphic structure of the limk1 gene in drosophila leads to changes in LIMK1 content and to defects in courtship behavior, sound production, and learning/memory. The results of the present study of three wild-type strains and mutant agn(ts3) with altered limk1 structure demonstrate that long-term memory is normal in Canton-S and Oregon-R but is impaired in Berlin and drastically suppressed in agn(ts3). This temperature-sensitive mutant carries the S-element from the Tc1/mariner family insertion near the dlimk1 3'-UTR and, compared to Canton-S, has a reverse pCREB distribution in adult neuromuscular junctions (NMJ) of the second dorsal imago nerve before and after learning. Moreover, only agn(ts3) demonstrates amyloid-like aggregate formation in NMJ. This suggests that this impedes pCREb transport and thereby impairs the formation of short- and long-term memory.

[Neurogenetics and Neuroepigenetics].

"Genetics of behavior," or "Neurogenetics," is based on the evolutionary ideas of T. Dobzhansky on brain development and behavior. It continues with the "experimental genetics of higher nervous activity" of I. Pavlov and uses a comparative approach in the study of heredity and variation in behavioral manifestations, from Protozoa to humans. The study of the classical Pavlovian conditioned reflex in mutant Drosophila helped to identify the main types of memory and their evolutionary conservatism. Long-term memory defects are caused by mutations of the same genes as in mental, retardation in humans, when signaling cascades intersecting with the cAMP-dependent pathway are damaged. The cascade of actin remodeling is also among these. The key enzyme, LIM-kinase 1, controls cognitive manifestations of the "genomic disease" Williams deletion syndrome. Its study resulted in the recognition of neuroepigenetics as an interface between the genome and environmental influences. Epigenetic factors of "variability"--DNA methylation, histone acetylation, and microRNA regulation--do not change the structure of the gene but its manifestations. Certain miRNAs have already been considered to be both biomarkers for neurodegenerative diseases and factors of the intergenerational transmission of the behaviorial properties of ancestors who experienced stress from adverse environmental influences.

Diffusive Propagation of Exciton-Polaritons through Thin Crystal Slabs.

If light beam propagates through matter containing point impurity centers, the amount of energy absorbed by the media is expected to be either independent of the impurity concentration N or proportional to N, corresponding to the intrinsic absorption or impurity absorption, respectively. Comparative studies of the resonant transmission of light in the vicinity of exciton resonances measured for 15 few-micron GaAs crystal slabs with different values of N, reveal a surprising tendency. While N spans almost five decimal orders of magnitude, the normalized spectrally-integrated absorption of light scales with the impurity concentration as N(1/6). We show analytically that this dependence is a signature of the diffusive mechanism of propagation of exciton-polaritons in a semiconductor.

[Learning and memory in Drosophila: physiologic and genetic bases].

Elucidation of molecular mechanisms of cognitive functions is one of the major achievements in neurobiology. At most, this is due to the studies on the simple nervous systems, such as the CNS in Drosophila melanogaster. Many of its functional characteristics are pretty similar to higher vertebrates. Among these are: 1) evolutionary conservation of genes and molecular systems involved in the regulation of learning acquisition and memory formation; 2) presence of highly specialized and differentiated sensory, associative and motor centers; 3) utilization of similar modes of informational coding and analysis; 4) availability of major learning forms including non-associative, as well as associative learning; 5) diversity of different memories, including short-term- and protein synthesis- dependent long-term memory; 6) presence of aminergic reinforcement systems in the brain; 7) feed-back loops of circadian clocks, current organism experience and individual organism characters affecting cognitive process per se. In this review the main attention is paid to the two mostly studied Drosophila learning forms, namely to olfactory Iearning and courtship suppression conditioning (CCS). A separate consideration is given to the impacts of kynurenins and metabolite of actin remodeling signal cascade.