Synthesis and biological evaluation of novel mono- and bivalent ASGP-R-targeted drug-conjugates

Asialoglycoprotein receptor (ASGP-R) is a promising biological target for drug delivery into hepatoma cells. Nevertheless, there are only few examples of small-molecule conjugates of ASGP-R selective ligand equipped by a therapeutic agent for the treatment of hepatocellular carcinoma (HCC). In the present work, we describe a convenient and versatile synthetic approach to novel mono- and multivalent drug-conjugates containing N-acetyl-2-deoxy-2-aminogalactopyranose and anticancer drug – paclitaxel (PTX). Several molecules have demonstrated high affinity towards ASGP-R and good stability under physiological conditions, significant in vitro anticancer activity comparable to PTX, as well as good internalization via ASGP-R-mediated endocytosis. Therefore, the conjugates with the highest potency can be regarded as a promising therapeutic option against HCC.     

Increased efficiency in the disinfection of sewage by lactic acid bacteria

The antimicrobic properties have been studied in 30 strains of lactobacilli. As a result a strain, the strongest antagonist relative to choleric vibrios and other enteropathogenic microorganisms, is selected. Lactobacilli are found to retain their viability and biological activity in the activated sludge during the whole period of observation (6 months). Biological disinfection of sewage is shown possible to be intensified using the activated sludge inoculated by the culture of the selected lactobacilli strain.     

Organization of higher-level chromatin structures (chromomere,chromonema and chromatin block) examined using visible light-induced chromatin photo-stabilization

The method of chromatin photo-stabilization by the action of visible light in the presence of ethidium bromide was used for investigation of higher-level chromatin structures in isolated nuclei. As a model we used rat hepatocyte nuclei isolated in buffers which stabilized or destabilized nuclear matrix. Several higher-level chromatin structures were visualized: 100nm globules-chromomeres, chains of chromomeres-chromonemata, aggregates of chromomeres-blocks of condensed chromatin. All these structures were completely destroyed by 2M NaCl extraction independent of the matrix state, and DNA was extruded from the residual nuclei (nuclear matrices) into a halo. These results show that nuclear matrix proteins do not play the main role in the maintenance of higher-level chromatin structures. Preliminary irradiation led to the reduction of the halo width in the dose-dependent manner. In regions of condensed chromatin of irradiated nucleoids there were discrete complexes consisting of DNA fibers radiating from an electron-dense core and resembling the decondensed chromomeres or the rosette-like structures. As shown by the analysis of proteins bound to irradiated nuclei upon high-salt extraction, irradiation presumably stabilized the non-histone proteins. These results suggest that in interphase nuclei loop domains are folded into discrete higher-level chromatin complexes (chromomeres). These complexes are possibly maintained by putative non-histone proteins, which are extracted with high-salt buffers from non-irradiated nuclei.     

Morpho-functional features in adolescent males under iodine deficiency of the Saratov region

An auxological study of 538 adolescent males (from 12 to 17) from different settlements of the Saratov region with various degrees of industrialization and iodine deficiency was carried out. All subjects have undergone an ultra-sound screening of thyroid volume to reveal the frequency of endemic goiter in each group. The results obtained during investigation showed the existence of deviations in the physical development of boys with goiter in skinfold thickness, body circumferences (chest, shoulder, and forearm), biacromial and biiliocristal diameters, transversal and sagittal chest diameters, body height and weight, BMI, leg length, and corpus length, all of which are greater in healthy adolescents (SD = 1.0, p = 0.000). In 46 subjects with endemic goiter, characteristics of metabolic status were investigated by the method of registration of endogenous intoxication (Malakhova, 1995). In comparison to the control group, a 1.2 times lower LAMM level in erythrocytes (p < 0.05) and 1.1 in urine (p < 0.05), and an increase by 2.3 in the LAMM level in blood plasma (p < 0.01) were detected. The relative percentage of catabolic substances exceeded the control values by 3.2 (p < 0.001). The OP level in erythrocytes is reduced by 2.2 (p < 0.01), in urine (p < 0.01) by 8.4. The OP level is higher in plasma by 3.0 (p < 0.01). The adolescents with endemic goiter have a reallocation of protein matter between erythrocytes, plasma and urine. The spectrogram of erythrocytes shows lowering metabolites on membrane frames, which testifies to the destruction of the structurally functional properties of erythrocytes, and a lowering of absorption properties in glycocalix erythrocytes.     

Stages of the cerebral mechanisms of deceptive responses

Cerebral mechanisms of perceiving and telling lies were studied by recording event-related potentials (ERPs) both after an actual deceptive response and during the time interval when the subject decided to tell a lie. Ten healthy volunteers participated in the study. The test consisted of their playing a game against a computer. The subjects could choose between deceptive and truthful answers so as to win the game. The subjects gave a deceptive answer intentionally, the structure of the test ensuring equal numbers of deceptive and truthful answers. The relaxation times in the cases of truthful and deceptive answers did not differ significantly from each other. The comparison of ERPs accompanying deceptive and truthful answers showed the existence of a negativity with a latent period of 90 ms in the regions of the right frontal, central, and right parietal derivations. This negativity indicated that the brain reacted to a deceptive answer even if this a priori “erroneous” act ensured reaching the goal and, in this sense, was subjectively relevant. In terms of the cerebral error detector mechanism, this phenomenon may be regarded as a special case of a general response of the brain to giving an incorrect (deceptive) answer, rather than a response to a lie per se. The interval of time when, presumably, the decision on a deceptive answer was being made was found to contain the late positive component P540, which is most likely to be involved in the preparation of the deceptive answer and the intention to tell a lie.     

Study of the structural and structure-functional subdomains in the interphase nucleus by photostabilization

The role of the nuclear matrix components in the organization of structural and functional domains of interphase nuclei was studied using irradiation with blue light in the presence of a photosensibilized agent (Ethidium bromide). Nuclear domain resistance to extractive solution (2 M NaCl) treatment served as a criterion of irradiation-induced stabilization of different nuclear domains. The following results have been obtained: 1) the structural organization of the complexes of chromatin and clusters of replication does not depend on the state of the nuclear matrix in isolated nuclei; 2) chemical stabilization of the nuclear matrix by Cu(2+)-ions is not sufficient for the organization of chromatin domains; 3) irradiation in the presence of Ethidium bromide stabilizes domains of the nuclei, but does not lead to stabilization of the nuclear matrix internal network. Hence, the irradiation prevented extraction from the nuclear domains of nonhistone proteins which were not standard matrix proteins. Based on the results obtained, a hypothesis was proposed about a coexistence of two groups of nonhistone proteins in the cell nucleus. The first group includes proteins of the nuclear matrix involved in immobilization of scafford attachment regions and active genes. The second group includes some hypothetical structural proteins participating only in compaction of DNA of condensed chromatin.     

Basic properties of populations generated in the frame of one-parameter discrete model of genetic diversity

Previously, when discussing the properties of one parameter discrete model of genetic diversity (M.Yu. Shchelkanov et al, J. Biomol. Struct. Dyn. 15, 887-894 (1998)), we took into account Hamming distance distribution only between precursor and arbitrary descendant sequences. However, really there are sets of sequence populations produced during amplification process. In the presented work we have investigated Hamming distance distributions between sequences from different descendant sets produced in the frame of one parameter discrete model. Two basic descendant generation operators (so called amplifiers) are introduced: 1) the last generation amplifier, L, which produces descendants with precursor elimination; 2) all generations amplifier, G, which produces descendants without precursor elimination. Generalization of one-parameter discrete model for the case when precursor sequences do not coincide are carried out. Using this generalization we investigate the distribution of Hamming distances between L- and G-generated sequences. Basic properties of L and G operators, L/G-choice alternative problem have been discussed. Obtained results have common theoretical significance, but they are more suitable for high level genetic diversity process (for example, HIV diversity).     

The Xenopus laevis centrosome aurora/Ipl1-related kinase.

The cDNA encoding the protein kinase pEg2 was originally cloned through a differential screening performed during the early development of Xenopus laevis. pEg2 orthologues were found in various organisms and were classified in a new family of oncogenic mitotic protein kinases named 'aurora/Ipl1-related kinases' after the Drosophila melanogaster gene aurora and the Saccharomyces cerevisiae gene Ipl1. The catalytic activity of pEg2 is necessary for the mitotic microtubule spindle formation in Xenopus laevis egg extracts. The addition of a dominant negative form of pEg2 to in vitro spindle assembly assays leads to monopolar spindles generated by a defect of centrosome separation. In Xenopus cultured cells, pEg2 was confined around the pericentriolar material once centrosomes were duplicated. The centrosome localization does not depend on the presence of microtubules. However, in vitro, the protein binds to taxol-stabilized microtubules independently of its kinase activity. During mitosis the location of the protein changes, in metaphase the kinase localizes on the microtubules at the poles of the mitotic spindle whereas it is not present on astral microtubules. This localization persists until the segregation of the chromosomes is completed. The presence of the kinase on the spindle may reveal another yet unknown function.     

Visualization of early chromosome condensation: a hierarchical folding, axial glue model of chromosome structure

Current models of mitotic chromosome structure are based largely on the examination of maximally condensed metaphase chromosomes. Here, we test these models by correlating the distribution of two scaffold components with the appearance of prophase chromosome folding intermediates. We confirm an axial distribution of topoisomerase IIalpha and the condensin subunit, structural maintenance of chromosomes 2 (SMC2), in unextracted metaphase chromosomes, with SMC2 localizing to a 150-200-nm-diameter central core. In contrast to predictions of radial loop/scaffold models, this axial distribution does not appear until late prophase, after formation of uniformly condensed middle prophase chromosomes. Instead, SMC2 associates throughout early and middle prophase chromatids, frequently forming foci over the chromosome exterior. Early prophase condensation occurs through folding of large-scale chromatin fibers into condensed masses. These resolve into linear, 200-300-nm-diameter middle prophase chromatids that double in diameter by late prophase. We propose a unified model of chromosome structure in which hierarchical levels of chromatin folding are stabilized late in mitosis by an axial "glue."