Interaction of bivalent copper, nickel, manganese ions with native DNA and its monomers

UV differential spectroscopy is applied to study the interaction of Cu2+, Ni2+, Mn2+ ions with deoxyribonucleotides of canonic bases (dGMP, dAMP, dCMP, dTMP) and native DNA. Heteroatoms of the bases, coordinating ions, and binding constants which characterize the formation of metal complexes are found. The affinity of the ions is lower for the deoxyribonucleotide bases than for the ribonucleotide ones. This indicates that 02' of ribose participates in the stabilization of the metal complex even under conditions close to the neutral one (pH 6). Unlike the Cu2+ ions, Ni2+ and Mn2+ ions do not interact with N3C both in monomers and polymers. This seems to be the main factor explaining why copper makes DNA transform into a structure with a quasi-Hoogsteen pairing of GC pairs. No transformations of this kind of helix-coil transitions are caused by manganese and nickel up to concentrations 4 X 10(-2) M.     

Distribution of CCR5-delta 32 gene deletion across the Russian part of Eurasia

We describe the cases of two premature infants carrying a central venous line who developed on the fourth day of life a catheter related intracardiac thrombus. Although they were clinically asymptomatic we opted for thrombolytic treatment considering the potential risks of this situation. Treatment with recombinant tissue plasminogen activator (rt-PA) was performed for one day in the first case and for three days in the second one, in association with fresh frozen plasma. Thrombus dissolution occurred in both patients and no adverse effects were noted. In our experience tissue plasminogen activator was a therapy acceptably safe and effective inducing clot lysis in very low birthweight neonates into critical situations.     

Variability analysis of HIV-1 gp120 V3 region: IV. Distribution functions for intra- and inter-subtype amino acid hamming distances

Distribution functions for intra- and inter- HIV-1 V3-loop subtypes amino acid Hamming distances were calculated (850 V3-loop sequences from the Los Alamos HIV-1 Database (1996) were used). These functions have pronounced bell-like shape. Such shapes of the histograms for HIV-1 V3 intra- and inter-subtype distriutions are discussed to confirm the applicability of different hierarchical cluster procedures for HIV-1 V3 classification. Two-mode distribution for the subtype E could sertificate that this subtype includes two thinner taxons.     

The syndecan family of proteoglycans. Novel receptors mediating internalization of atherogenic lipoproteins in vitro

Cell-surface heparan sulfate proteoglycans have been shown to participate in lipoprotein catabolism, but the roles of specific proteoglycan classes have not been examined previously. Here, we studied the involvement of the syndecan proteoglycan family. First, transfection of CHO cells with expression vectors for several syndecan core proteins produced parallel increases in the cell association and degradation of lipoproteins enriched in lipoprotein lipase, a heparan-binding protein. Second, a chimeric construct, FcR-Synd1, that consists of the ectodomain of the IgG Fc receptor Ia linked to the highly conserved transmembrane and cytoplasmic domains of syndecan-1 directly mediated efficient internalization, in a process triggered by ligand clustering. Third, internalization of lipase-enriched lipoproteins via syndecan-1 and of clustered IgGs via the chimera showed identical kinetics (t1/2 = 1 h) and identical dose-response sensitivities to cytochalasin B, which disrupts microfilaments, and to genistein, which inhibits tyrosine kinases. In contrast, internalization of the receptor-associated protein, which proceeds via coated pits, showed a t1/2 < 15 min, limited sensitivity to cytochalasin B, and complete insensitivity to genistein. Thus, syndecan proteoglycans can directly mediate ligand catabolism through a pathway with characteristics distinct from coated pits, and might act as receptors for atherogenic lipoproteins and other ligands in vivo.     

Scattering of light from histologic sections: a new method for the analysis of connective tissue

We have developed a light scattering technique that can be used to analyze the orientation and diameter of collagen fibers in histologic sections of connective tissue. Scattering patterns obtained by transmitting laser light through sections of tissue contain information both on the orientation, degree of alignment, and size of the constituent collagen fibers. Analysis of the azimuthal intensity distribution of scattered light yields numerical values of the degree of alignment by use of an orientation index, S, which is chosen to vary between 0 for randomly oriented fibers and 1 for a perfectly aligned arrangement. The average diameter of the collagen fibers is calculated from the scattering angle at which the intensity reaches its first minimum. These measurements are independent of the nature of histologic stain. The procedure is illustrated by measurements obtained with sections of the guinea pig dermis and of control scar. We conclude from our experiments that light scattering can complement the analysis of tissue architecture typically performed with the light microscope.     

The effect of iodine-containing x-ray contrast media on water status in the blood plasma

The impact of radio-opaque agents on human blood plasma water pool was studied by using relaxation proton magnetic resonance methods with a pulse gradient of magnetic field. The findings suggest that blood plasma water imbalance was induced by human serum albumin dehydration processes after RCN-HSA interaction.     

Homology in natural cryptic plasmids of Bacillus subtilis

Peculiarities of DNA homology in a number of cryptic plasmids isolated from soil bacillary strains and related or identical to Bacillus subtilis were studied. Fragments generated after digestion of one of these plasmids, p1414, were employed as a probe for blot hybridization with identical fragments of other plasmids. The data obtained suggest that nearly all the studied plasmids possess a common homology site that occupies a significant plasmid portion. Regions of detectable and weak homology were located throughout this site. Moreover, plasmid p1414 was shown to carry a large site that lacks homology with plasmids belonging to two groups. Eventually, one of these plasmids demonstrates complete lack of homology with the remaining plasmids.     

Cytogenetic and molecular genetic diagnostics of Rett syndrome in children]

Rett syndrome in 32 children (31 girls and 1 boy) was diagnosed according to International association on Rett syndrome. The phenomenon of the presence of special type of late-replicating chromosome X (type C) was revealed. This phenomenon may be recommended as a diagnostic test for both preclinical periods of development of the disease and in atypical cases of Rett syndrome.