[Possibilities of dynamic phase contrast MRI of cerebrospinal fluid for performing a tap test in a patient with idiopathic normotensive hydrocephalus]. / Vozmozhnosti dinamicheskoi fazovo-kontrastnoi MR-likvorografii pri vypolnenii tap-testa u patsienta s idiopaticheskoi normotenzivnoi gidrotsefaliei.

Idiopathic normotensive hydrocephalus (iNH) is a widespread disease in elderly patients. The effectiveness of iNG treatment and the subsequent quality of patients' lives directly depends on timely and early diagnosis. The criteria for diagnosing iNG that are used in neuroimaging can also be found in patients without clinical manifestations of this disease, and the widely used tap-test is an invasive technique with a rather low sensitivity. The need for early diagnosis and initiation of treatment before the development of irreversible damage to brain structures determines the relevance of the search for an accessible, minimally invasive, accurate and safe diagnostic method. The article presents a clinical observation of the use of phase-contrast MRI of cerebrospinal fluid (CSF) in a female patient with a positive response to the tap test with a quantitative analysis of changes in CSF flow parameters and ALVI and Evans indices depending on the time after CSF evacuation. Phase-contrast MRI of CSF with a quantitative assessment of CSF flow parameters in combination with an assessment of the ALVI index has the potential to increase the accuracy of diagnosing iNH and is of scientific interest for further research.

Ecological Characteristics of Antarctic Fungi.

In view of the high responsiveness of polar ecosystems to the global climate change, the research of Antarctic microorganisms has become a topical issue. The unique ecosystems that have developed under the severe climate conditions of the continent lack flowering plants but are dominated by soil mycobiota. In addition to performing their classical ecological functions, Antarctic fungi form the basis of local communities, e.g., endoliths and microbial mats. Furthermore, Antarctic fungi are a major force that mediates transformation of rock minerals in situ and makes biologically significant elements available for other organisms. For these reasons, mycobiota plays a central role in the maintenance of ecological equilibrium in Antarctica. The dominant fungal division on the continent is Ascomycota (77.1%), and not Basidiomycota (9.1%), as it is the case on other continents. For a number of reasons, yeasts and yeast-like micromycetes (mainly basidiomycetes) are more tolerant to extreme conditions in various Antarctic biotopes than filamentous fungi. Substantial evidence suggests that filamentous fungi and yeasts are better adapted to existence in ecosystems with extremely low temperatures than other microorganisms. Due to the long-term isolation of Antarctica from other continents, local biota has been evolving largely independently, which led to emergence of multiple endemic fungal taxa. The presence of eurytopes on the continent is presumably related to the global warming and growing anthropogenic pressure. This review discusses the current state of research on the structure of fungal communities of Antarctic subaerial and subaquatic biotopes, the ecological role of yeast-mycelial dimorphism in Antarctic fungi, the problem of endemism of Antarctic mycobiota, as well as the ecological and physiological adaptations of fungi to low temperatures; it also justifies the relevance of research into secondary metabolites of psychrophilic micromycetes.

Enzymatic and Antimicrobial Activities in Polar Strains of Microscopic Soil Fungi.

Potential to produce inducible enzymes (several hydrolases and oxidases) and antibiotics as secondary metabolites was studied in soil micromycete strains from the Arctic (Franz Josef Land and Novaya Zemlya) and Antarctica (the oases Thala Hills, Larsemann Hills, Schirmacher, and Marie Byrd Land). Maximal esterase activity was observed in strains of two typical Antarctic species, Hyphozyma variabilis 218 and Thelebolus ellipsoideus 210 (51 and 29 nmol FDA/((g mycelium h), respectively). Cellulolytic activity was maximal (89 µmol glucose/mg biomass) in Ascochyta pisi 192. Extracellular phenol oxidase (laccase) and peroxidase activities were not detected in the strains examined. Antibacterial activity toward Bacillus subtilis ATCC 6633 was observed in 75% of the Antarctic micromycete strains. Higher-activity strains were isolated from organic-rich moist habitats with a moss or lichen cover. Maximal activities were displayed by Paecilomyces marquandii 166, Penicillium janczewskii 165, Penicillium roseopurpureum 169, and Thelebolus ellipsoideus 210. Antagonistic activity toward Antarctic bacterial strains was shown by 77% of the microfungal strains examined. Maximal inhibition was observed with strains of the typical Antarctic species Antarctomyces psychrotrophicus MT303855 and the eurytopic species Sarocladium kiliense MT303856. Antimycotic activity was observed in 42% of the strains. Both activities were detected in 38% of the Antarctic strains.

Complex partial synchronization patterns in networks of delay-coupled neurons.

We study the spatio-temporal dynamics of a multiplex network of delay-coupled FitzHugh-Nagumo oscillators with non-local and fractal connectivities. Apart from chimera states, a new regime of coexistence of slow and fast oscillations is found. An analytical explanation for the emergence of such coexisting partial synchronization patterns is given. Furthermore, we propose a control scheme for the number of fast and slow neurons in each layer. This article is part of the theme issue 'Nonlinear dynamics of delay systems'.

Ionic conductivity and its effect on the optical properties of LBO crystals.

Temperature dependence of the dielectric losses conditioned by the ionic conductivity (IC) of nonlinear optical lithium triborate (LBO) crystals was investigated both theoretically and experimentally, exploiting the variation of the line form of LBO piezoelectric resonances with temperature. An effect of the IC on the optical properties of LBO crystals was considered. The relation between the LBO IC and its resistance to UV radiation was investigated.

RMS roughness-independent tuning of surface wettability by tailoring silver nanoparticles with a fluorocarbon plasma polymer.

A layer of 14 nm-sized Ag nanoparticles undergoes complex transformation when overcoated by thin films of a fluorocarbon plasma polymer. Two regimes of surface evolution are identified, both with invariable RMS roughness. In the early regime, the plasma polymer penetrates between and beneath the nanoparticles, raising them above the substrate and maintaining the multivalued character of the surface roughness. The growth (ß) and the dynamic (1/z) exponents are close to zero and the interface bears the features of self-affinity. The presence of inter-particle voids leads to heterogeneous wetting with an apparent water contact angle θa = 135°. The multivalued nanotopography results in two possible positions for the water droplet meniscus, yet strong water adhesion indicates that the meniscus is located at the lower part of the spherical nanofeatures. In the late regime, the inter-particle voids become filled and the interface acquires a single valued character. The plasma polymer proceeds to grow on the thus-roughened surface whereas the nanoparticles keep emerging away from the substrate. The RMS roughness remains invariable and lateral correlations propagate with 1/z = 0.27. The surface features multiaffinity which is given by different evolution of length scales associated with the nanoparticles and with the plasma polymer. The wettability turns to the homogeneous wetting state.

In situ coupling of chitosan onto polypropylene foils by an Atmospheric Pressure Air Glow Discharge with a liquid cathode.

Atmospheric air plasma treatment of chitosan solutions leads to degradation of chitosan molecules by OH radicals and is accompanied by a predominant cleavage of glycosidic linkages and by a decrease of the molecular weight. The degradation proceeds via first order kinetics with the rate constant of (5.73±0.22)×10(-6)s(-1) and the energetic yield of chitosan bond scission of (2.4±0.2)×10(-8)mol/J. Products of degradation together with intact chitosan molecules adsorb and form coatings on polypropylene foils immersed into the solution that is being plasma treated. The plasma treatment results in strong binding of chitosan to polypropylene due to the formation of covalent bonds between the activated polymer surface and chitosan molecules. Plasma-driven crosslinking is responsible for the accumulation of compressive stress which leads to the development of buckling instabilities in the chitosan coatings.

Structure and Functions of Linker Histones.

Linker histones such as variants H1, H5, and other similar proteins play an important role in regulation of chromatin structure and dynamics. However, interactions of linker histones with DNA and proteins, as well as specific functions of their different variants, are poorly studied. This is because they acquire tertiary structure only when interacting with a nucleosome, and because of limitations of currently available methods. However, deeper investigation of linker histones and their interactions with other proteins will address a number of important questions - from structure of compacted chromatin to regulation of early embryogenesis. In this review, structures of histone H1 variants and its interaction with chromatin DNA are considered. A possible functional significance of different H1 variants, a role of these proteins in maintaining interphase chromatin structure, and interactions of linker histones with other cellular proteins are also discussed.

Sum frequency generation of UV laser radiation at 266 nm in LBO crystal.

We report experimental results of generation at 266 nm in LBO crystal by frequency mixing of the fundamental (1064 nm) and third harmonic (355 nm) of ytterbium pulsed fiber laser radiation. Deep ultraviolet (DUV) output power of 3.3 W at 266 nm was achieved with 14% IR-to-DUV conversion efficiency. UV-induced bulk degradation of LBO crystals was observed and visualized by the dark field method.

[THE TECHNIQUE OF HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY FOR SIMULTANEOUS DIAGNOSTIC OF INHERENT HYPERPLASIA OF ADRENAL GLANDS TYPE I AND II].

The article considers the technique of high-performance liquid chromatography making it possible simultaneously detect cortisol, cortisone and secondary steroids in serum for consequent analysis of common reversed-phase high-performance liquid chromatography with ultraviolet under 240 nm. The liquid-liquid extraction from alkaline medium in diethyl ether The separation using column of 150x4.6 size ODS 3.5 mkm in isocratic mode. The eluent acetonitrile--0.02 M phosphate buffer pH 8.0--isopropanol (40:60:1). The application of proposed technique managed to separate cortisol, cortisone, dexamethasone, corticosterone, 11-desoxicortisol, testosterone, desoxicorticosterone, 17α-gidroxiprogesterone and androstendion in 20 minutes. The simplicity, reproducibility and sufficient selectivity and sensitivity of technique permit implement it in clinical practice for simultaneous diagnostic of inherent hyperplasia of adrenal glands type I and II.

[THE SIMULTANEOUS ANALYSIS OF FREE CATECHOLAMINES AND METANEPHRTNES IN URINE USING TECHNIQUE OF HIGHLY EFFECTIVE LIQUID CHROMATOGRAPHY WITH FLUORIMETRIC DETECTION AND SOLID PHASE EXTRACTION ON POLYMERIC SORBENT (PUROSEP-200)].

The article considers the technique of simultaneous detection of free catecholamines and free metanephrines in urine using inverse phase highly effective liquid chromatography with fluorimetric detection. The solid phase extraction was implemented on cartridges with 30 mg of hyper cross-linked polystyrene (Purosep-200). The simplicity, reproducibility and sufficient sensitivity of technique permit applying it in clinical practice to diagnose pheochromocytoma.

[Molecular mechanisms of regulaion of transcription by PARP1].

Poly-ADP-ribosylation is a covalent post-translational modification of nuclear proteins that plays a key role in the immediate response of cells to genotoxic stress. Poly(ADP-ribose) polymerase (PARP) synthesizes long and branched polymers of ADP-ribose onto acceptor regulator proteins, and thereby change their activity. Metabolism of poly-ADP regulates DNA repair, cell cycle, replication, aging and death of cells, as well as remodeling of chromatin structure and gene transcription. PARP1 is one of the most common nuclear proteins; it is responsible for production of -90% of the polymers of ADP-ribose in the cell. PARP1 inhibitors are promising antitumor agents. At the same time, the current inhibitors target the catalytic domain of PARP1 that leads to.a number of side effects. Therefore, considering the potential benefits of PARP1 inhibitors for the treatment of multiple diseases, it is necessary to develop new strategies of PARP1 inhibition. PARP1 has a modular structure and has catalytic, transcription and DNA-binding activities. The review focuses primarily on the role of PARP1 in transcriptional regulation; the structure and functional organization of PARP1, as well as multiple ways of regulation of chromatin remodeling, DNA methylation and transcription are covered in detail. Studies of the molecular mechanisms of regulation of transcription factor PARP1 can serve as a basis for search and design of new inhibitors.

[Paradoxical embolism: clinical situation and approaches to treatment].

The authors describe two clinical cases of paradoxical embolism of greater-circulation vessels in patients with thrombosis of deep veins of the lower extremities and patent foramen ovale, also discussing different variants of clinical course of paradoxical embolism, as well as approaches to treatment and prevention.

[HPLC analysis of dehydroepiandrosterone sulfate in serum with use of solid-phase extraction on hyper cross-linked polystyrene (Purosep-200)].

We have developed a simple HPLC method for analysis of the dehydroepiandrosterone sulfate (DHEA-sulfate) in serum with use a new procedure of solid-phase extraction (SPE) on hyper cross-linked polystyrene (Purosep-200) and fast chromatographic separation on the monolithic column under isocratic elution and UV detection at 200 nm. Complete SPE procedure lasts for about 7 min, chromatographic separation takes less than 6 min. Simplicity and high reproducibility of this method makes it attractive in routine clinical practice.

[Modified HPLC method of determination of the valproic acid in biological fluids].

Proposed modified HPLC method for determination of valproic acid in biological fluids. Created solid-phase extraction of valproic and heptanoic acids (internal standard, IS) on the cartridges packed hyper cross-linked polystyrene which maintain some tens extractions without losses of efficiency. Carboxylic acids are derivative with 1-(bromoacetyl)pyrene in acetone at presence of triethylamine. Chromatographic separation of derivatives is performed on Chromolith Perfonnance RP-18e columns, which packed unique monolithic sorbent. UV detection at 360 nm. Mobile phase acetonitrile - water (90:10, v/v) plus 1% isopropanol, speed flow 2000 microL/min, pressure 21 bar. Complete chromatographic cycle less than 3 minutes. Yield of IS and valproic acid (extraction plus derivatization) was 101-106%. Sensitivity (limit detection) was near 1 ng for valproic and near 0.6 ng for heptanoic acid during signal/noise ratio = 3.

[Molecular mechanisms of transcription through a nuclesome by RNA polymerase II].

The Pol II-type mechanism is conserved from yeast to human. After initiation of transcription, Pol II can be paused within the early transcribed region of a gene. Then Pol II overcomes the initial nucleosomal barrier, and efficiently proceeds through chromatin. At low- to moderate-level transcription progression of Pol II is characterized by displacement/exchange of only H2A/H2B dimer(s) and hexasome survival, likely mediated through formation of small intranucleosomal DNA loops. This mechanism helps to preserve the "histone" code during transcription. As the transcription rate is increased, the distance between transcribing Pol II complexes becomes shorter, and trailing Pol II complexes may encounter the hexasome formed after previous transcription round, before the H2A/H2B dimer re-binds to the hexasome. In this case an unstable intermediate with a smaller number of DNA-histone contacts is formed, resulting in eviction of the histone hexamer from DNA in vitro; therefore here all core histones are evicted/exchanged in vivo. Various protein factors and histone chaperones are involved in chromatin transcription by Pol II in vivo.

Binding of DNA methyltransferase M.Ecl18kI [corrected] to operator-promoter region decreases its methylating activity.

The type II bifunctional DNA methyltransferase (MTase) Ecl18 that is able to control transcription of its own gene was studied kinetically. Based on initial velocity dependences from S-adenosyl-L-methionine (AdoMet) and target DNA and substrate preincubation assays, it is proposed that the enzyme apparently works by a rapid equilibrium ordered bi-bi mechanism with DNA binding first. By measuring the enzyme activity depending on DNA and AdoMet at different fixed concentrations of the operator sequence oligonucleotide, it was found that its binding has noncompetitive inhibitory effect on Ecl18 MTase activity.

Investigation of unusual growth and phenotypic characteristics of plasmid-containing and plasmid-free strains of oligotrophic bacterium Ancylobacter vacuolatus.

The oligotrophic bacterium Ancylobacter vacuolatus contains two large plasmids pREV1 and pREV2 (about 150 and 250 kb, respectively). Plasmid pREV1 carries the genes responsible for resistance to chloramphenicol, trimethoprim and y-irradiation. Plasmid pREV2 carries the genes responsible for resistance to beta-lactam antibiotics and formation of gas vacuoles. The ability to grow under oligotrophic conditions did not depend directly on either plasmid and was probably chromosome-encoded. Nevertheless, strains lacking the pREV2 plasmid had an improved capacity for growth in enriched media, as is evident from the following findings: 1) the growth rate of the strains lacking pREV2 was about 60% higher with an induction time of about two times less than those for strains carrying the plasmid; 2) the overall cell yield in rich media and colony size on non-oligotrophic agarized media increased with removal of pREV2; 3) the characteristic change in cell morphology occurring in the wild type ofA. vacuolatus when switched from oligotrophic to eutrophic growth conditions was not observed in the strains lacking pREV2; 4) bacterial strains lacking pREV2 exhibited significantly higher rRNA content than the parent strain. As a possible explanation for these phenomena, we suggest that the pREV2 plasmid carries gene(s) for protein(s) acting as repressor(s) of expression of some enzymes involved in eutrophic metabolism. Such protein(s) probably participate in switching between the oligotrophic and eutrophic types of metabolism in response to changing nutrient supply in the environment.

[HPLC determination of plasma/serum homocysteine and cysteine with UV detection and solid-phase extraction on a polymeric sorbent].

Isocratic HPLC determination of plasma/serum homocysteine and cysteine with separation on reversed-phase column and UV detection at 330 nm is proposed. The mobile phase consist of acetonitrile - 0.05 M citrate-phosphate buffer with pH 2.4 - isopropanol (15:85:1, v/v/v). Full separation of cysteine, cysteamine (IS), glutathione and homocysteine was achieved within less than 10 minutes. Reduction of thiols from disulfides was performed by 1,4-dithioerithreitol, and derivatization by with Ellman's reagent [5'5-dithiobis-(2-nitrobenzoic acid)]. After that plasma/serum, containing derivatives of thiols, is cleared and concentrated on cartridge packed with 10 mg of hypercross-linked polystyrene (Purosep-200). Elution from cartridge is made with water-organic solvent (without evaporation and concentration, but without dilution), as well as waterless solvents (with evaporation and concentration). Simplicity, reproducibility in combination with high cleanliness of extracts and sufficient sensitivity (0.4 ng for homocysteine, 2 ng for glutathione and 0.2 ng for cysteine and cysteamine at a signal/noise ratio > 3), make this method suitable for routine clinical application.

[A simple and highly sensitive high-performance liquid chromatography assay of salivary putrescine and cadaverine].

A simple and highly sensitive high-performance liquid chromatography assay is proposed to test salivary diamines (putrescine and cadaverine). Derivation was carried out with the orthophthalic aldehyde 2-mercaptoethanol. A rapid purification procedure for derivatives on the cartridges packed with 10 mg of hypercrosslinked polystyrene (Purosep-200) was first developed. Separation was made on a Chromolith (Merck), 100 x 4.6 mm in size, with monolithic reverse-phase silica gel (RP-18e) in the isocratic mode with ultraviolet (UV) detection at 230 nm. The eluent contained 55% acetonitrile and 45% 0.01 M phosphate buffer pH 6.8, added by 1% of isopropanol; flow rate was 1400 pl/min; pressure was 28 bars. Complete separation of diamine derivatives lasted at least 5 min. The sensitivity of the assay with UV detection (230 nm) was about 0.1 ngfor diamines and about 0.5 ng for the internal standard (IS) at a signal/noise ratio of 3.0, which enabled diamines to be determined in I pl (0.001 ml) of saliva. The simplicity, reproducibility, and high sensitivity of the assay along with the feasibility of its application on standard chromatographic equipment (an isocratic pump and an UV detector) make it suitable for routine clinical application.