186,259 research outputs found
R factor-mediated adhesiveness to mammalian cells in E. coli K12.
No full textWe checked the possible effects of the standard plasmids of known compatibility groups on the ability of three strains of E. coli K12, J62, J53 and C600, to agglutinate human and guinea pig erythrocytes and to adhere to cultures of human epithelial cells. The results obtained showed that under defined experimental conditions one plasmid, R478, from a clinical isolate of Serratia marcescens is able to modulate the adhesive properties of the strain J62 which lacks adhesiveness. On the contrary, the same factor did not alter the ability of strains J53 and C600 to agglutinate erythrocytes and to adhere to human epithelial cells in culture, nor did it induce adhesive properties in wild-type strains of E. coli from clinical isolates that lacked them. This would suggest a possible plasmidic control of chromosomally encoded surface structures that mediated adhesiveness of E. coli to mammalian cells
The behaviour of inorganic and organic cations in the Debye-Hückel layer of DNA
No full textThe behaviour of inorganic and organic cations in the Debye-Hückel layer of DN
Analyses of Fatty Acid Binding Protein from Gallus Domesticus and its complexes
No full textAnalyses of Fatty Acid Binding Protein from Gallus Domesticus and its complexe
Monitoring folding transitions of synthetic, branched-chain polymeric polypeptides by capillary zone electrophoresis
No full textThe coil/helix transition of a synthetic, branched-chain polymeric polypeptide (poly (Lys(Glu(1)-DL-Ala(3))EAK), 50-Lys residues long in the backbone, as a function of increasing molarities of methanol in solution, is here studied by both, circular dichroism (CD) and capillary zone electrophoresis. CD spectra showed that, at 75% v/v methanol, the transition from random coil to fully helical structure was obtained, in a pH 1.1 HCI solution in the presence of 20 mM NaCI. CZE studies, run in parallel, exhibited the classical unfolding to folding sigmoidal transition, with mid-point at 60% v/v methanol concentration, plateauing at ca. 80% v/v organic solvent. Surprisingly, though, such unfolding to folding transition was accompanied by an expansion, rather than a contraction, of the resulting ordered polypeptide. As the charge of the polypeptide (a pure polycation at a pH of 2.1 in CZE) was kept rigorously constant, a plot of the radius of the polymer along the sigmoidal transition clearly showed that the radius of gyration of the helical, structured polypeptide was in fact larger than that of the random coil. Such results were confirmed by molecular dynamics simulations, which indicated that the dimensions of such polypeptide, in alpha-helix configuration, were 8.5 nm (in length) and 3.2 nm (in diameter), whereas those of the corresponding random coil were 7.2 nm (in length) and 5.1 nm (length of shorter axis). It would thus appear that the randomized structure assumes the shape of a more compact object, roughly resembling a "rugby ball"
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Structural studies of human acidic fibroblast-growth factor (FGF1) mutants with a probable anticancer activity
No full textLectins are carbohydrate-binding proteins ubiquitously present in nature. They play a role in biological recognition phenomena
involving cells and proteins. The interaction lectin-carbohydrate is highly specific, and can be exploited for the development
of nanoparticles containing on their surface lectins specifically directed to carbohydrate residues present only on malignant
cells and absent on healthy ones [1].
Lectins have been found to possess anticancer properties and they are proposed as therapeutic agents, binding to cancer cell
membranes or their receptors, causing cytotoxicity, apoptosis and inhibition of tumor growth. Some lectins are able to
prevent the proliferation of malignant tumor cells because they recognize the T-antigen (Gal β 1–3GalNAc) found specifically
on the surface of tumor cells [2]. The main problem is that their use as a detection agent for the T-antigen in clinical studies
is not possible because the immune system can recognize them as foreign molecules and develop an immune response.
Previous studies with X-ray crystallography made in our laboratory have characterized a lectin found in mushrooms called
BEL β-trefoil which has antiproliferative activity on tumor cell lines, because it contains three binding sites for the T-antigen.
Unlike other lectins with this property, BEL β-trefoil shows structural homology with a human protein, acidic Fibroblast
Growth Factor (FGF1) [3]. Superposition of their structures suggests that the human protein could be mutated to contain at
least one of the binding sites for the T-antigen. Such mutations should create in FGF1 the potential capacity of recognizing
tumor cells with less immunogenicity than the fungal protein. FGF1 is mitogenic and chemotactic, and mediates cellular
functions by binding to transmembrane receptors, which are activated by ligand-induced dimerization requiring heparin as
co-receptor.
To reach our purpose, the FGF1 cDNA was cloned into a bacterial plasmid and then mutated in four different positions to
eliminate its mitogenic activity and to engineer in the protein the T-antigen binding capacity. Attempts to crystalize the
mutants of FGF1 were made using the hanging drop technique with the final aim to carry out their structural characterization
by X-ray diffraction analysis of the crystals.
[1] Lis H and Sharon N. Lectins as molecules and as tools. Annu Rev Biochem. 1986. 55(1): p. 35-67.
[2] Ju T, Otto VI, Cummings RD. The Tn antigen-structural simplicity and biological complexity. Angew Chem Int Ed Engl.
2011. 50(8): p.1770-1791.
[3] Bovi M, Cenci L, Perduca M, Capaldi S, Carrizo ME, Civiero L, Chiarelli LR, Galliano M, Monaco HL. BEL β-trefoil: a
novel lectin with antineoplastic properties in king bolete (Boletus edulis) mushrooms. 2013. Glycobiology. 23(5): p. 578-592.
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Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Chicken Liver (Basic) Fatty Acid-Binding Protein and its Complexes with Lipophilic Ligands
No full textChicken Liver (Basic) Fatty Acid-Binding Protein and its Complexes with Lipophilic Ligand
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