1,720,959 research outputs found
Novel Poly(urethane-aminoamides). An in vitro study of the interaction with heparin.
No full textIn order to obtain heparin-binding polyurethanes, tertiary amino-groups have been introduced in the polymer backbone by attributing a key-role to the chain extender, i.e. substituting butanediol, commonly used in polyurethane synthesis, with a tailor-made diamino-diamide-diol. In this work a poly(ether-urethane-aminoamide) (PEU/PIME/al) was obtained with poly(oxytetramethylene) glycol 2000, 1,6-hexamethylene-diisocyanate and the new chain extender, in the molar ratio 1:2:1. The heparin binding capacity of PEU/PIME/al was evaluated with 125I labelled heparin, using for comparison the analogous polymer obtained with a diamide-diol (i.e. the poly(ether-urethane-amide) PEU/PIBLO/al), and two commercially available biomedical polyurethanes (Pellethane 2363 and Corethane). pH and ionic strength dependence of the heparin uptake were investigated by treating all the polyurethanes with solutions of 125I heparin into buffers from pH 4 to 9 or NaCl molarity from 0.0 to 1.0. The stability of the interaction with bound heparin was investigated by sequential washing treatments (PBS, 1 N NaOH, 2% SDS solution), then analysing the residual radioactivity on the materials. Results indicated that the heparin binding of PEU/PIME/al is significantly higher and more stable than that of the other polyurethanes, with a time-dependent kinetic. The interaction with heparin appears to be prevalently ionic, with the contribution of other electrostatic and hydrophobic interactions. Activated partial thromboplastin time (APTT), performed on human plasma with polyurethane-coated, heparinized test tubes, indicate
Antibody response to fibronectin-binding adhesin FnbpA in patients with Staphylococcal aureus infections
No full textWe have analyzed antibody reactivity to a fibronectin-binding microbial surface component that recognizes
adhesive matrix molecules (MSCRAMM) in blood plasma collected from patients with staphylococcal infections.
All patients had elevated levels of anti-MSCRAMM antibodies compared to those of young children who,
presumably, had not been exposed to staphylococcal infections. The anti-MSCRAMM antibodies preferentially
reacted with the ligand-binding repeat domain of the adhesin. However, these antibodies did not inhibit fibronectin
binding. Essentially, all patients had antibodies which specifically recognized the fibronectin-MSCRAMM
complex but not the isolated components. Epitopes recognized by these anti-ligand-induced binding sites antibodies
were found in each repeat unit of the MSCRAMM. These results demonstrate that staphylococci have
bound fibronectin some time during infection and that each repeat unit in the MSCRAMM can engage in
ligand binding. Furthermore, our previously proposed model, suggesting that an unordered structure in the
MSCRAMM undergoes a conformational change upon ligand binding (K. House-Pompeo, Y. Xu, D. Joh, P. Speziale,
and M. Ho ̈o ̈k, J. Biol. Chem. 271:1379–1384, 1996), is presumably operational in patients during infections
Monoclonal antibodies to CNA, a collagen-binding microbial surface component recognizing adhesive matrix molecules, detach staphylococcus aureus from a collagen substrate.
No full textPrevious studies showed that Staphylococcus aureus expresses a collagen-binding MSCRAMM (Microbial Surface Component Recognizing Adhesive Matrix Molecules), CNA, that is necessary and sufficient for S. aureus cells to adhere to cartilage and is a virulence factor in experimental septic arthritis. We have now used a monoclonal antibody (mAb) approach to further analyze the structure and function of CNA. 22 mAbs raised against the minimal ligand binding domain, CNA-(151-318), were shown to bind to the MSCRAMM with similar affinity. All mAbs appear to recognize conformation-dependent epitopes that were mapped throughout the CNA-(151-318) domain using a chimeric strategy where segments of CNA are grafted on ACE, a structurally related MSCRAMM from Enterococcus faecalis. These mAbs were able to inhibit (125)I-collagen binding to CNA-(151-318) as well as to intact S. aureus cells. They also interfered with the attachment of bacteria to collagen substrates. Furthermore, some of the mAbs could effectively displace (125)I-collagen bound to the bacteria. These displacing mAbs were also able to detach bacteria that had adhered to a collagen substrate in a preincubation, raising the possibility that some of the mAbs may be used as therapeutic agents
Cross-reactive displacing antibodies from collagen-binding proteins and method of identification and use
No full textAntibodies to the CNA protein and to other regions from the collagen binding domain, including domain CNA19, are provided, and antibodies produced in this manner have been shown to be cross reactive to both Staphylococcus aureus and Staphylococcus epidermidis bacteria and which can thus be used in the prevention and treatment of infections caused by both of these types of bacteria. In addition,medical instruments can be treated using the antibodies of the invention in order to reduce or eliminate the possibility of their becoming infected or further spreading the infection. In particular, the proteins are advantageous because they are cross-reactive and may thus be administered to patients so as to reduce or prevent severe infection by staphylococcal bacteria of more than one species. Antibodies generated in this manner have also been shown to exibit displacement activity and can thus be utilized advantageously in mehtods wherein these antibodies will be administered to patients having pre-existingstaphylococcal infections because of the ability to displace bacterial proteins from binding sites on the extracellular matrix. Finally, a method of identifying, isolating and utilizing displacing antibodies is also provided
Caratterizzazione biochimica ed immunologica di adesine da S. Aureus con attivita' di legame per la fibronectina ed il collagene
No full textDottorato di ricerca in biochimica. 12. ciclo. A.a. 1998-99Consiglio Nazionale delle Ricerche - Biblioteca Centrale - P.le Aldo Moro, 7, Rome; Biblioteca Nazionale Centrale - P.za Cavalleggeri, 1, Florence / CNR - Consiglio Nazionale delle RichercheSIGLEITItal
Identification and characterization of a new ligand-binding site in FnbB, a fibronectin-binding adhesin from Streptococcus dysgalactiae
No full textStreptococcus dysgalactiae S2, a bovine mastitis isolate, expresses the fibronectin (Fn)-binding adhesin FnbB. Here, we describe a new fibronectin-binding domain called UFnBD, located 100 amino acid N-terminal to the primary repetitive Fn-binding domain (FnBRD-B) of FnbB. UFnBD interacted with N-terminal region of Fn (N29) and this binding was mostly mediated by type I module pair 2-3 of N29 fragment, whereas FnBRD-B mainly bound to type I module pair 4-5. Furthermore, UFnBD inhibited adherence of S. dysgalactiae to Fn but at lower level as compared to FnBRD-B. UFnBD exclusively shared antigenic properties with the Fn-binding unit Du of FnbpA from Staphylococcus aureus but not with ligand-binding domains or motifs of other adhesins, while Fn-induced determinants of FnBRD-B and other adhesins appeared to be conformationally related. Consistent with this, a monoclonal antibody 7E11 generated from a mouse immunized with FnbB, and that recognized UFnBD did not cross-react with FnBRD-B. The epitope for 7E11 was mapped to 40 amino acid long segment within UFnBD and interaction between the antibody and the epitope was specifically induced by Fn or N29. A similar antibody epitope was observed in Streptococcus pyogenes strains suggesting the presence of an adhesin bearing epitope related to FnbB
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe 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
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