1,720,988 research outputs found
Metallic based nanotechnology: applications in diagnosis and therapeutics
No full textIn recent years the fields of medicine and biology assist to an ever-growing innovation related to the development of nanotechnologies. In the pharmaceutical domain, for example, liposomes, polymer based micro and nanoparticles have been subjects of intense research and development during the last three decades. In this scenario metallic particles, which use was already suggested in the first half of the ’80, are now experiencing a real renaissance. In the field of diagnosis, magnetic resonance imaging is one of the first and up to now the most developed application of metallic particles. But beside this application, a very new generation of biosensors based on the optical properties of colloidal gold and fluorescent nanocrystals, called quantum dots seems to be ready to be implemented in diagnosis and medical imaging. Concerning therapeutic applications, the potentialities of metal nanoparticles to help fulfilling the need of time and space controlled release of drugs has been intuited for a long time. Nowadays, magnetically guided carriers or thermal responsive matrices, in which drug release is triggered by the heating of metal nanoparticles, are effective examples of their application in drug delivery, while more recently efforts to develop metallic nanoobjects to be used as vectors of nucleic acids for vaccination and transfection have been multiplied. In the future, one of the most interesting challenges is certainly the use of metallic nanoparticles for an innovating, effective and selective physical treatment of solid tumors via targeted intracellular hyperthermia
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
Physicochemical characterization of ultrasmall superparamagnetic iron oxide particles (USPIO) for biomedical application as MRI contrast agents
No full textA review. Ultrasmall superparamagnetic iron oxide (USPIO) particles are maghemite or magnetite nanoparticles currently used as contrast agent in magnetic resonance imaging. The coatings surrounding the USPIO inorg. core play a major role in both the in vitro stability and, over all, USPIO's in vivo fate. Different physicochem. properties such as final size, surface charge and coating d. are key factors in this respect. Up to now no precise structure - activity relationship has been described to predict entirely the USPIOs stability, as well as their pharmacokinetics and their safety. This review is focused on both the classical and the latest available techniques allowing a better insight in the magnetic core structure and the org. surface of these particles. Concurrently, this work clearly shows the difficulty to obtain a complete physicochem. characterization of USPIOs particles owing to their small dimensions, reaching the anal. resoln. limits of many com. instruments. An extended characterization is therefore necessary to improve the understanding of the properties of USPIOs when dispersed in an aq. environment and to set the specifications and limits for their conception
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
PEGylation and preliminary biocompatibility evaluation of magnetite-silica nanocomposites obtained by high energy ball milling
No full textHigh energy ball milling (HEBM) has been used for the first time to prepare PEGylated magnetite-silica (Fe3O4-SiO2) nanocomposites intended to be used for biological purposes. Surface amine groups were introduced by a silanization reaction involving 3-aminopropyl triethoxysilane (APTS) followed by PEGylation to yield long-term stable and stealth nanocomposites of 200nm in diameter. The efficient coverage by PEG chains was shown by isothermal titration calorimetry (ITC) where PEGylated nanocomposites did not interact with BSA compared to non-PEGylated counterparts which led to a significant change in enthalpy. By cell viability (MTT) assays and cell morphology investigations, it was evidenced that PEGylated Fe3O4-SiO2 nanocomposites did not provide any appreciable cytotoxicity on J774 macrophage and MCF-7 breast cancer cell lines. Furthermore, noticeable internalization was evidenced by J774 cells with PEGylated Fe3O4-SiO2 nanocomposites in contrast to MCF-7 cells, in good agreement with the respective tendency of each cell line for endocytosis. © 2010 Elsevier B.V
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
Specific antitumor targetable beta-cyclodextrin-poly(ethylene glycol)-folic acid drug delivery bioconjugate.
No full textThe tumor targeting properties of a new drug carrier synthesized by bioconjugation of folic acid (FA) to beta-cyclodextrins through a poly(ethylene glycol) (PEG) spacer (CD-PEG-FA) were investigated. Surface plasmon resonance demonstrated that CD-PEG-FA specifically interacts with immobilized folate binding protein (FBP) while the naked beta-cyclodextrins do not display any specific interaction. In vitro studies demonstrated that CD-PEG-FA was devoid of cell toxicity. [(3)H]-folic acid/CD-PEG-FA competition binding investigations performed with folate receptor overexpressing human epidermal carcinoma KB cells showed that CD-PEG-FA had about 14 times lower tumor cell binding capacity than free folic acid. The carrier cell trafficking properties were investigated using rhodamine-B as fluorescent probe, which possesses 3000 and 4580 M(-)(1) inclusion constants for CD-PEG-FA and beta-cyclodextrins, respectively. Cell-associated fluorescence measurements showed that CD-PEG-FA does not promote the rhodamine-B uptake into non-folate receptor expressing human lung carcinoma MCF7 cells while 19% higher accumulation in KB cells was found with respect to rhodamine-B loaded beta-cyclodextrins. Confocal laser scanning microscopy indicated the presence of cytosolic red fluorescent spots after 2 h of incubation of KB cells with rhodamine-B included CD-PEG-FA. The fluorescent dye resided primarily in small spots, namely, endosomes and multivesicular bodies. At 1 h after pulsed incubation, wider red fluorescent cellular structures appeared as a fusion of previous structures
Specific antitumor targetable beta-cyclodextrin-poly(ethylene glycol)-folic acid drug delivery bioconjugate
No full textThe tumour targeting properties of a new drug carrier synthesised by bioconjugation of folic acid to beta-cyclodextrins through a PEG spacer (CD-PEG-FA) were investigated. Surface plasmon resonance demonstrated that CD-PEG-FA interacts specifically with immobilized folate binding protein (FBP) with apparent dissociation constant of 3.59 nM while the naked beta-cyclodextrins did not display any specific interaction. Cell culture studies showed that CD-PEG-FA was devoid of cell toxicity. [3H] folic acid/CD-PEG-FA competition binding investigations performed with over-expressing folate receptor human epidermal carcinoma KB cells showed that CD-PEG-FA had about 10 times lower tumour cell binding capacity than folic acid free. The carrier cell trafficking properties were investigated using rhodamine-B as fluorescent probe, which possesses 3000 M-1 and 4600 M-1 inclusion constants for CD-PEG-FA and beta-cyclodextrins, respectively. Cell associated fluorescence measurements showed that CD-PEG-FA did not promote the rhodamine-B uptake into non-folate receptor expressing human lung carcinoma MCF7 cells while 19% higher accumulation in KB cells was found with respect to native beta-cyclodextrins. Confocal laser scanning microscopy evidenced the presence of cytosolic red fluorescent spots after 2 hours incubation of KB cells with rhodamine-B CD-PEG-FA inclusion. The fluorescent dye resided primarily into small spots, namely endosomes and multi-vescicular bodies. At 1 hour after pulsed incubation wider red fluorescent cellular structures appeared as fusion of previous structures
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