A 1,4-dihydropyridine derivative reduces DNA damage and stimulates DNA repair in human cells in vitro

Compounds of the 1,4-dihydropyridine (1,4-DHP) series have been shown to reduce spontaneous, alkylation- and radiation-induced mutation rates in animal test systems. Here we report studies using AV-153, the 1,4-DHP derivative that showed the highest antimutagenic activity in those tests, to examine if it modulates DNA repair in human peripheral blood lymphocytes and in two human lymphoblastoid cell lines, Raji and HL-60. AV-153 caused a 50% inhibition of growth (IC50) of Raji and HL-60 cells at 14.9+/-1.2 and 10.3+/-0.8mM, respectively, but did not show a cytotoxic effect at concentrations <100 microM. Alkaline single-cell gel electrophoresis (comet) assays showed that AV-153 reduced the number of DNA strand breaks in untreated cells and also in cells exposed to 2 Gy of gamma-radiation, 100 microM ethylmethane sulfonate (EMS), or 100 microM H2O2. DNA damage was reduced by up to 87% at AV-153 concentrations between 1 and 10nM, and a positive dose-effect relationship was seen between 0.01 and 1 nM. Comparison of the kinetics of DNA strand-break rejoining in the presence and absence of AV-153 revealed a considerable influence on the rate of repair. In view of the resemblance of this compound's structure to that of dihydronicotinamide, a substrate for poly(ADP-rybose)polymerase, the modulation of DNA repair by AV-153 could involve an influence on poly(ADP)ribosylation.     

Validation of the Results of Genome-Wide Association Studies of Tuberculosis in Russians of West Siberia

The genetically mediated ability of the host to provide an adequate immune response to the pathogen plays an important role in the development of tuberculosis infection. Genome-wide association studies performed in different populations revealed the association of a number of chromosomal regions with the development of tuberculosis (TB). At the same time, full characteristics of the factors of genetic susceptibility to the disease remains an unresolved problem, and the associations identified are not always reproduced in studies in other populations. A total of 45 single nucleotide polymorphisms (SNPs) were analyzed in 768 individuals, including 323 tuberculosis patients and 445 healthy individuals. Analysis of associations of tuberculosis with genetic markers was carried out using logistic regression. Permutations were used to account for multiple comparisons. Nominal statistically significant association with tuberculosis was detected for two SNPs, rs10515787 (intronic variant of the EBF1 gene) and rs10956514 (intronic variant of the ASAP1 gene) (p = 0.005 and 0.049, respectively). After the permutation test, only one of the associations was preserved, for rs10515787 (p = 0.003). Thus, in Russians from the city of Tomsk, the association of rs10515787 at the EBF1 gene with the development of tuberculosis was confirmed. However, the results of this study identify rare A allele as a risk factor for the development of TB, while in an earlier study, it was identified as being protective relative to the risk for developing of tuberculosis. The revealed “reverse association” is an interesting fact that requires further investigation.     

Donor function of phosphate ions in photosystem 2

Evidence was obtained for the interaction between the photosystem 2 (PS2) reaction centre (RC) chlorophyll (Chl) P680 and inorganic phosphate, Pi. The light-induced endogenous basal electron transport to ferricyanide in PS2 depended on endogenous Pi. The electron transport in phosphate deficient chloroplasts was absent, and could be resumed upon the addition of exogenous Pi or of the exogenous electron donor, diphenylcarbazide. Some chloroplast Chl molecules were apparently bound with Pi to a complex via the magnesium atom that was detected by the increase in absorbance in the Chl a absorption maximum at 435 nm observed after the consumption of endogenous Pi in the photophosphorylation reactions. The electron paramagnetic resonance (EPR) Signal I, found in the spectra at 77 K after irradiation of frozen samples in chloroplasts poor in endogenous Pi, was the sum of P700+ and P680+ signals. The P680+ signal disappeared after addition of Pi, diphenylcarbazide or diuron to the chloroplasts before freezing. In addition, the EPR doublet signal of the phosphate anion radicals was recorded at 77 K after irradiation in the ethanol solutions of Chl a containing potassium phosphate. The same doublet signal was discovered in the difference EPR spectrum "chloroplasts minus chloroplasts with diuron" at 77 K after irradation. The results are a possible evidence of the participation of phosphate ions in the primary light reactions of PS2. This revised version was published online in June 2006 with corrections to the Cover Date.     

Laboratory and clinical study of nitazole]

Nitazole, a drug from the nitrotiazole group, was shown to be active in vitro against bacteroides, peptococci, peptostreptococci, clostridia, staphylococci, colibacilli and streptococci. By its activity and antibacterial spectrum nitazole had some advantages over metronidazole, a drug from the nitroimidazole group. Experimental study of nitazole aerosole formulation in 4 models of purulent wounds of rabbits infected by Bacteroides fragilis, B. melaninogenicus, Clostridium perfringens 27 and Staphylococcus aureus 209P revealed its high therapeutic efficacy. In the treatment of 37 patients with purulent wounds of the soft tissues including 12 cases isolating anaerobic microbes, the clinical process of the acute suppuration in all the patients at the average reduced to the 5th-7th day. By the data of the bacteriological and cytological examinations the wound surface was ready for putting in stitches or free perforated cutaneous graft by the 10th-12th day. The drug tolerance was good. No adverse reaction were observed under the nitazole dressing in any case during the treatment of the wounds.     

Structural Alterations in Human Fibroblast Growth Factor Receptors in Carcinogenesis

Fibroblast growth factor (FGF) plays an important role in human embryogenesis, angiogenesis, cell proliferation, and differentiation. Carcinogenesis is accompanied by aberrant constitutive activation of FGF receptors (FGFRs) resulting from missense mutation in the FGFR1-4 genes, generation of chimeric oncogenes, FGFR1-4 gene amplification, alternative splicing shift toward formation of mesenchymal FGFR isoforms, and FGFR overexpression. Altogether, these alterations contribute to auto-and paracrine stimulation of cancer cells and neoangiogenesis. Certain missense mutations are found at a high rate in urinary bladder cancer and can be used for non-invasive cancer recurrence diagnostics by analyzing urine cell pellet DNA. Chimeric FGFR1/3 and amplified FGFR1/2 genes can predict cell response to the targeted therapy in various oncological diseases. In recent years, high-throughput sequencing has been used to analyze exomes of virtually all human tumors, which allowed to construct phylogenetic trees of clonal cancer evolution with special emphasis on driver mutations in FGFR1-4 genes. At present, FGFR blockers, such as multi-kinase inhibitors, specific FGFR inhibitors, and FGF ligand traps are being tested in clinical trials. In this review, we discuss current data on the functioning of the FGFR family proteins in both normal and cancer cells, mutations in the FGFR1-4 genes, and mechanisms underlying their oncogenic potential, which might be interesting to a broad range of scientists searching for specific tumor markers and targeted anti-cancer drugs.     

Distribution and conservation of mobile elements in the genus Drosophila

Essentially nothing is known of the origin, mode of transmission, and evolution of mobile elements within the genus Drosophila. To better understand the evolutionary history of these mobile elements, we examined the distribution and conservation of homologues to the P, I, gypsy, copia, and F elements in 34 Drosophila species from three subgenera. Probes specific for each element were prepared from D. melanogaster and hybridized to genomic DNA. Filters were washed under conditions of increasing stringency to estimate the similarity between D. melanogaster sequences and their homologues in other species. The I element homologues show the most limited distribution of all elements tested, being restricted to the melanogaster species group. The P elements are found in many members of the subgenus Sophophora but, with the notable exception of D. nasuta, are not found in the other two subgenera. Copia-, gypsy-, and F-element homologues are widespread in the genus, but their similarity to the D. melanogaster probe differs markedly between species. The distribution of copia and P elements and the conservation of the gypsy and P elements is inconsistent with a model that postulates a single ancient origin for each type of element followed by mating-dependent transmission. The data can be explained by horizontal transmission of mobile elements between reproductively isolated species.      

Microbial ecology of the intestines in health and in pathology

Bifidoflora constitute 85--95 per cent of the large intestine microbiocenosis in children under 1 year of age. Bacteroides are not specific of children under 6 months of age. Lactobacilli, lactic acid streptococci, colon bacilli, enterococci and staphylococci (saprophytic, epidermal) constitute not more than 15 per cent. The predominating group peculiar of eubiosis in adults includes bifidobacteria and bacteroides. Changes in human autoflora are often induced by such factors as impaired ecology, stress, uncontrolled use of antibacterial drugs, radio- and chemotherapy, etc. Dysbacteriosis (first of all lower quantitative contents of bifidoflora) has an unfavourable effect on the intestine secretory function, absorption and certain indices of protein, lipid and mineral metabolism, vitamin synthesizing and fermentative functions and leads to disfunction of the gastrointestinal tract. It is a cause of persisting and relapsing infections in children and adults. High and optimal levels of bifidoflora in the intestine usually prevent the pathogenic action of pathogens. Lysozyme of digestive secretion and secretory immunity with immunoglobulin A prevalence also play an important role in the complicated mechanism of the protective barrier. The use of bacterial preparations such as bifidumbacterin, lactobacterin or bifilact for stabilization and recovery of high bifidoflora levels is indicated in all the cases with impaired microbiocenosis of the intestine.     

The involvement of adherens junction components in myofibrillogenesis in cultured cardiac myocytes.

The distribution of adherens junction (AJ) components was investigated in cultured heart myocytes. These cells, derived from either newborn rats or chick embryos, develop elaborate arrays of myofibrils which become extensive and laterally aligned following several days in culture. The Z-disks in these cells, visualized by immunolabeling with antibodies to muscle-specific alpha-actinin, exhibit a characteristic periodicity of about 2 microns and are in register with those of neighboring myofibrils throughout the sarcoplasm. Vinculin, in these cells, associates with intercellular AJ and cell-matrix adhesions. In addition, this protein is detected in periodic bands located along the lateral cell membranes corresponding to "costamers" previously described by Pardo, J.V., Siliciano, J.D. and Craig, S.W. (Proc. Natn. Acad. Sci. USA, 80, 1008). Similarly, N-cadherin, which is predominantly associated with intercellular junctions, is also detected in periodic striations located mainly on the dorsal and lateral cell surfaces. Using computer-aided three-dimensional microscopy confirmed that these vinculin- and N-cadherin-containing structures are located in extrajunctional sites, apparently associated with Z-disks of peripheral myofibrils. Based on these findings an alternative pathway is proposed for the assembly of vinculin and N-cadherin, which is not triggered by adhesive interactions with extracellular surfaces but rather by interactions at the membrane-cytoplasm interphase with the periphery of the pre-assembled myofibrils. Moreover, we present evidence that antibodies to N-cadherin, which are capable of blocking AJ formation in culture, have an inhibitory effect also on the development and alignment of myofibrils. We discuss the functional significance of the "costameric" organization of vinculin and N-cadherin and consider its involvement both in the lateral alignment of neighboring muscle cells and in the stabilization of developing myofibrils.     

Actin interaction with the plasma membrane fraction of the cells from a suspension subline of murine L fibroblasts

Effect of plasma membranes of murine fibroblasts cultivated in suspension on actin polymerization was studied. Using low shear viscometry of actin-membrane mixtures together with the number of extractions of membranes with actin depolymerizing buffers it was found that at least two polypeptides 220 and 94 kDa may be involved into the actin filaments-plasma membrane interaction.