1,720,959 research outputs found
Modified polyethylene glycols and their supramolecular complexes with biologically active macromolecules
No full textThe present invention in a first aspect relates to a polymer based on modified polyethylene glycol (PEG) of formula CH3-(OCH2CH2)n-O-X-A, wherein (OCH2CH2)n- is a polyoxyethylene chain wherein n varies from 100 to 5000, X is a saturated or unsaturated C1C20 linear alkyl group or a saturated or unsaturated C3-C5 branched alkyl group having at least one end functionalised with a hydroxyl, amino, carboxylic or thiol group, and A is a functional lipophilic group. In another aspect, the invention relates to supramolecular complexes of the polymers of polyethylene glycol (PEG) that is modified with a biologically active macromolecule or a biopharmaceutical and their applications in therapy.
(FR)L'invention concerne, selon un premier aspect, un polymère à base de polyéthylène glycol modifié (PEG) de formule CH3-(OCH2CH2)n-O-X-A, dans laquelle (OCH2CH2)n- est une chaîne polyoxyéthylène dans laquelle n varie de 100 à 5000; X est un groupe alkyle C1C20 linéaire saturé ou insaturé, ou un groupe alkyle C3-C5 ramifié saturé ou insaturé dont au moins une extrémité est fonctionnalisée par un groupe hydroxyle, amino, carboxylique ou thiol; et A est un groupe lipophile fonctionnel. Dans un autre aspect, l'invention concerne des complexes supramoléculaires des polymères de polyéthylène glycol (PEG) modifiés avec une macromolécule biologiquement active ou un produit biopharmaceutique, et leurs applications thérapeutiques
PEGylation of Recombinant Human Granulocyte Colony-Stimulating Factor (r-h-G-CSF) Produced in Escherichia coli: a New Drug to Overcome Neutropenia
No full text
High-level expression of a recombinant active microbial transglutaminase in Escherichia coli
Full text linkBackground: Bacterial transglutaminases are increasingly required as industrial reagents for in vitro modification of proteins in different fields such as in food processing as well as for enzymatic site-specific covalent conjugation of therapeutic proteins to polyethylene glycol to get derivatives with improved clinical performances. In this work we studied the production in Escherichia coli of a recombinant transglutaminase from Streptomyces mobaraensis (microbial transglutaminase or MTGase) as enzymatically active chimeric forms using different expression systems under the control of both lac promoter or thermoinducible phage lambda promoter. Results: Thermoinducible and constitutive expression vectors were constructed expressing Met-MTGase with chimeric LacZ 1-8 PNP 1–20 or LacZ 1–8 fusion protein under different promoters. After transformed in competent Escherichia coli K12 strains were fermented in batch and fed-bach mode in different mediums in order to select the best conditions of expression. The two most performing fusion protein systems namely short thermoinducible LacZ 1–8 Met-MTGase from NP668/1 and long constitutive LacZ 1-8 PNP 1–20 Met-MTGase from NP650/1 has been chosen to compare both efficiency of expression and biochemical qualities of the product. Proteins were extracted, purified to homogeneity and verified as a single peak obtained in RP-HPLC. The LacZ 1-8 PNP 1–20 Met-MTGase fusion protein purified from NP650/1 exhibited an activity of 15 U/mg compared to 24 U/mg for the shorter fusion protein purified from NP668/1 cell strain. Conclusions: Combining the experimental data on expression levels and specific activities of purified MTGase fusion proteins, the chimeric LacZ 1-8 Met-MTGase, which displays an enzymatic activity comparable to the wild-type enzyme, was selected as a candidate for producing microbial transglutaminase for industrial applications.Pubblicat
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
Preclinical characterization of eleven new Cys-PEGylated hGH mutants
No full textWe synthesized and tested for biological activity eleven new PEGylated hGH derivatives. To this aim we used different strategies. A first group of PEGylable Cys derivatives was prepared by mutating into Cys single specific aminoacid residues located either in the connecting loop between helices 1 and 2 (Ile36 and Phe44) or in the connecting loop between helices 3 and 4 (Ile138 and Phe146). A second group of mutants was synthetized by inserting new Cys close to the aforementioned positions. Other PEGylable mutants were prepared by inserting a Gly4-Cys chain either at the N- or at the C-terminus of the hGH molecule. Finally, a Cys residue of the second hGH disulfide bond (Cys182-Cys189) was made available for PEGylation by mutating its companion Cys to open up the disulfide bridge. All these mutants were tested for their ability to affect Nb2 cell proliferation in vitro and showed different effects. Two mutations (Phe44Cys and +Cys47) severely impaired and two (Ile138Cys and Phe146Cys) increased hGH bioactivity. The mutation Cys189Ser was functionally silent whereas the remaining mutations caused a 15-50% decrease in activity. 20kDa-pegylation caused a dramatic decrease in bioactivity in all mutants. The r-hGH-(Ile138Cys)-Cys138-PEG derivative showed the highest activity (15% of wild-type unpegylated hGH) and was selected for pharmacockinetic studies in vivo. It showed a fivefold longer half-life and was significantly more effective than wild-type hGH in causing weight gain when given subcutaneously twice a week to hypophysectomized rats. In conclusion, even when it is directed to residues supposed to have a marginal role in the activity of this hormone, 20 kDa pegylation has detrimental effect on hGH bioactivity. These effects may be counterbalanced by the increase in half-life as it happens in pegylated Ile138Cys-hGH that could represent a promising new long-acting hGH derivative. Focal points:•Bedside: Current therapy of GH deficiency still has the important limitation of being delivered by daily subcutaneous injections and this reduces the compliance of the small pediatric patients. There is, therefore interest in developing long-acting GH derivative such as the new ones that we present here. •Benchside: By investigating the effect of Cys substitutions at aminoacidic positions that had not been investigated in previous studies, we obtained evidence that Ile138 and Phe146 have a role in GH bioactivity in vitro. •Industry: The mono-pegylated hGH mutant described in this work represents a promising candidate for human clinical pharmacology studies as long-acting derivative of h-GH.•Community: By decreasing the frequency of GH injections, long acting GH could decrease the costs of GH treatment and increase medication adherence
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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