Yttrium-Iron Garnet Film Magnetometer for Registration of Magnetic Nano- and Submicron Particles: In Vitro and In Vivo Studies.

In the current article, we present a new kind of magnetometer for quantitative detection of magnetic objects (magnetic nano- and submicron particles) in biological fluids and tissues. The sensor is based on yttrium-iron garnet film with optical signal registration system. Inheriting the working principle of a fluxgate magnetometers, the sensor works at a room-temperature, its wide dynamic range allows the measurements in an unshielded environment. A small size of sensitive element combined with a short recovery time after the excitation coils are off provide us with a potentially high spatial and temporal resolution of measurements. We show the feasibility of the developed devices by sensing the remanent magnetization of magnetic nanoparticles (MNPs) both in vitro (test tubes, dry MNPs) and in vivo (local injection of the MNPs into mice).

YIG-Based Sensor System for Millisecond Time Range Magnetorelaxometry.

In the current study we propose a magneto-optical system for registration and analysis of magnetic nano- and microparticles magnetic relaxation. The core of our system is the novel compact magnetometer based on an yttrium-iron garnet film and working at room temperature. The sensor demonstrates sensitivity of 35 pT/√{Hz} at 79 Hz and recovery time less than 100 µs, which allows to register quite fast magnetic relaxations of a low amplitude. All these facts make the system feasible for usage in biological magnetorelaxometry and theranostics. Statistical processing of the relaxation curves allowed us to estimate both amplitudes and relaxation times for various biocompatible magnetic particles at the amount of 100 µg in the test tubes experiments. The system has a great potential of further development for usage in the areas of targeted drug delivery, hyperthermia, magnetic imaging. Being comparatively cheap, the system potentially is of a great interest in the fields of biomedicine and nanomedicine.

Relativistic quantum key distribution system with one-way quantum communication.

Unambiguous state discrimination (USD) is one of the major obstacles for practical quantum key distribution (QKD). Often overlooked, it allows efficient eavesdropping in majority of practical systems, provided the overall channel loss is above a certain threshold. Thus, to remain secure all such systems must not only monitor the actual loss, but also possess a comprehensive information on the safe 'loss vs. BER' levels, which is often well beyond currently known security analyses. The more advanced the protocol the tougher it becomes to find and prove corresponding bounds. To get out of this vicious circle and solve the problem outright, we demonstrate a so called relativistic QKD system, which uses causality to become inherently immune to USD-based attacks. The system proves to be practical in metropolitan line-of-sight arrangements. At the same time it has a very basic structure that allows for a straightforward and comprehensive security analysis.

[Growth and photosynthetic activity of diatom Thalassiosira weissflogii at decreasing salinity].

The relative yield of variable chlorophyll fluorescence (Fv/Fm), rate of photosynthetic carbon fixation (P), growth rate, and production of extracellular photosynthates (Pec) was studied in diatom T. weissflogii in seawater with salinity decreasing from 35 to 15 and 5 per thousand. After incubation at 5 per thousand for 1 day, the diatom abundance (N) decreased as a result of death of a fraction of cells, while viable cells demonstrated decreased Fv/Fm and P, Pec was detectable, and cell division was likely inhibited. After incubation for 2 days, population started to grow, while exponential growth rate and the abundance by day 8 were lower compared to 35 per thousand. After incubation at 15 per thousand for 1 day, P was higher and Fv/Fm was lower compared to 35 per thousand. No cell death was observed and exponential growth rate insignificantly differed from that at 5 per thousand. The value of N by day 8 was lower compared to 35 per thousand but higher compared to 5 per thousand. The dependence of photosynthetic parameters and population dynamics of T. weissflogii on the relative salinity is discussed.

[Effect of the exogenous glucose on photosynthesis of the diatom Thalassiosira weissflogii depending on nitrate supply and light]. / Vliianie ékzogennoi gliukozy na fotosintez diatomovoi vodorosli Thalassiosira weissflogii v zavisimosti ot obespechennosti nitratami i urovnia osveshchennosti.

The rate of photosynthetic carbon fixation (P) in the diatom Thalassiosira weissflogii cultivated in the presence of exogenous glucose in the medium (0-10.56 micrograms C/l) at different levels of illumination (25, 50, and 100 microE/m2 s) was studied as a function of nitrate nitrogen supply. In the diatoms limited in nitrogen and assimilating exogenous glucose, P was found to decrease or increase depending on light intensity, glucose concentration, and the duration of exposure. In the diatoms assimilating both nitrate nitrogen and glucose, compared to those supplied with nitrates alone, P was higher at medium and high light intensities and lower at a low light intensity. The interrelation of the processes of carbon and nitrogen metabolism in mixotrophic algae and the ecological role of glucose consumption by phytoplankton are discussed.

Physico-chemical similarity of neurotransmitter receptor and transporter transmembrane domains.

Receptor and transporter of neurotransmitters similarity in ability of ligand-binding makes us consider them to possess the sites of similar structure and physico-chemical characteristics. However direct analysis of amino acid sequences alignment did not allow revealing such sites. For functionally similar proteins that differ in primary structure, the similarity extent is satisfactory estimated as based on physico-chemical properties of individual domain. We have analyzed transmembrane domains of a set of receptors and transporters of choline, norepinephrine, dopamine and serotonin. In our analysis in direction from extracellular border to intracellular one, amino acid sequences of transmembrane domains were divided into fragments each consisting of 4 amino acids. Every fragment was characterized by physico-chemical properties, such as hydrophilicity, hydrophobicity, polarity, etc. Hierarchical cluster analysis in space of the physico-chemical properties of these fragments was performed. As a result we have obtained both heterogeneous clusters, which contained receptor and transporter fragments, and homogeneous clusters which contained only receptor or transporter domains. An analysis of heterogeneous clusters has shown that the 4th, 5th and 6th transmembrane receptor domains and the 2d, 3d and 7th transmembrane transporter helices possess maximum similarity. The results obtained allow one to make a conclusion that these domains take part in formation of the ligand-binding centers.

[Features of the primary structure of DNA from the synaptonemal complex of the golden hamster]. / Osobennosti pervichnoi struktury DNK iz sinaptonemnogo kompleksa zolotistogo khomiachka.

DNA of golden hamster synaptonemal complex (SC) was cloned and partially sequenced. Computer analysis was performed to compare the SC DNA sequences for different families of eukaryotic genomic DNA. SC DNA is homologous to LINE family and in contrast to genomic DNA is enriched with alternative (GT/CA)n sequences and palindromes. By its ability to form potential hairpin loops, SC DNA is similar to nuclear matrix-associated regions of DNA (MARs) and differs considerably from DNA of microsatellite loci. It is noteworthy that SC DNA, which is supposed to be involved in meiotic recombination, and DNA of immunoglobulin genes, involved in somatic recombination, are both enriched with palindromes. The discovered peculiarities of the structure of hamster SC DNA allow us to join it with rat SC DNA into a special family of rodent genomic DNA sequences.

Ligand-receptor interactions. Multidimensional mathematical method of analysis.

The paper embraces information about the character of interaction between pharmacologically active ligands and 11 G-protein-dependent receptors of neurotransmitters. The data are analyzed by the methods of correlation and cluster analyses and of main components. An essential pharmacological affinity is revealed to exist between the receptors which regulate an inhibitory link of the adenylate cyclase system and receptors which activate Ca(2+)-mobilizing polyphosphoinositide system of secondary transmitters. Receptors which activate adenylate cyclase are rather different pharmacologically from two previous groups. Interrelation between the structure and physico-chemical properties of binding sites on receptors and efficiency of their interaction with ligand is discussed.

Similarity of the effects of tosyl-L-arginine methyl ester, atropine, caffeine and antitumour alkylating agent on some biological functions of thrombin and platelet 12-lipoxygenase.

The effect of the synthetic thrombin substrate (TAME) and three compounds exerting an opposite effect on Ca-PPI and AdC (caffeine, atropine and meta-tolyl derivative of mechlorethamine (TDM)) on hormone-like and catalytic functions of thrombin was studied. It is shown that both TAME and other drugs under test block effectively the thrombin-induced platelet aggregation, as well as protect the active site of the enzyme from denaturation by dithiothreitol. The same compounds inhibit thrombin in thrombin-fibrinogen reaction and platelet 12-lipoxygenase. These data suggest identity of thrombin moieties which determine its enzymatic and hormone-like activities.

[Leukocyte mobility in modulation of activity of the cell signalling system]. / Izuchenie podvizhnosti leikotsitov v usloviiakh moduliatsii aktivnosti signal'nykh sistem kletki.

The mobility of the rat polymorphonuclear leukocytes (PMNL) has been studied. It was shown, that it is greatly determined by the balance of adenylate cyclase (AdC) and Ca-polyphosphoinositide (Ca-PPI) cell signalling systems. Various compounds whose action on the activity of the signalling systems was previously connected with the membrane receptors, proved to be capable to affect the activity of submembrane elements of these systems. It is concluded that multiple areas of bioregulators fixation within the limits of the signal cascades are available.

[The significance of the functional status of the crural muscles in the pathogenesis of the postthrombophlebitic syndrome]. / Znachenie funktsional'nogo sostoianiia myshts goleni v patogeneze posttromboflebiticheskogo sindroma.

Venous stasis, disorders of oxygen metabolism and other disturbances in the post-thrombophlebitic syndrome result in reduction of the contractile function of the crus, i.e. muscle pumping capacity. Mutual influence of these factors result finally in the development of the so-called "vicious circle". Results of a study of 90 patients with different stages of the post-thrombophlebitic syndrome show a clear correlation between the stage of the disease and degree of reduction of the functional capacity of sural muscles. Measures for restoration of the contractile capacity of the crural muscles are advocated.

[Histamine metabolism and its role in central nervous system function]. / Obmen gistamina i ego rol' v funktsionirovanii TsNS.

The present day data concerning biosynthesis, storage, release and inactivation of histamine in the brain of mammals are given. The possibility to regulate histamine of the action of physiologically active substances is discussed.

[Histochemical study of tanycytes in connection with the adrenocorticotropic function of the hypophysis]. / Gistokhimicheskoe issledovanie tanitsitov v cviazi s adrenokortikotrofnoi funktsiei gipofiza

Chronic experiments were conducted on sexually mature rats; histochemical study of the activity of some redox enzymes (glutamic dehydrogenase, lactic dehydrogenase, glucoso-6-phosphoric dehydrogenase, glycerophosphoric dehydrogenase, and succinic dehydrogenase) was carried out in the ependymal cells of the floor of the third cerebral ventricle, the so called tanycytes, in case of an increased adrenocorticotrophic function of the hypophysis attained by bilaterial adrenalectomy, and in depression of this function as a result of chronic dexametasone administration. The activity of the enzymes under study decreased 2, 3 and 4 weeks after bilateral adrenalectomy. The activity of lactic dehydrogenase, glucerophosphoric dehydrogenase and succinic dehydrogenase increased in the tanycytes during administration of 5 gamma of dexametasone. Chronic administration of 100 gamma of dexametasone was accompanied by a toxic action of the preparation (a marked reduction in the weight of the adrenal glands, a negative body weight gain, and an aggravation of the animal's general condition). The results obtained pointed to the existence of a reverse correlation between the metabolic activity of tanicytes and the adrenocorticotrophic function of the hypophysis.