1,720,982 research outputs found
Drug interaction potential of resveratrol
No full textResveratrol is a naturally occurring polyphenol that is often used as a food supplement. Many positive health effects, including cardio protection, tumor suppression, and immune modulation, are associated with the intake of resveratrol. Resveratrol is well tolerated in healthy subjects without any comedication. However, supplemental doses of resveratrol in the range of 1 g/day or above by far exceed the natural intake through food. Whether resveratrol-drug interactions can be harmful in patients taking additional medications remains unknown. Recent in vivo studies and clinical trials indicate a possible drug-drug interaction potential using high-dosage formulations. In this review, the known in vitro and in vivo effects of resveratrol on various cytochrome P450 (CYP) isoenzymes are summarized. They are discussed in relation to clinically relevant plasma concentrations in humans. We conclude that resveratrol may lead to interactions with various CYPs, especially when taken in high doses. Aside from systemic CYP inhibition, intestinal interactions must also be considered. They can potentially lead to reduced first-pass metabolism, resulting in higher systemic exposure to certain coadministrated CYP substrates. Therefore, patients who ingest high doses of this food supplement combined with additional medications may be at risk of experiencing clinically relevant drug-drug interactions
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Targeting of hepatocytes using vector-conjugated liposomes : evaluation of targeting strategies
Get PDFThe need for specific targeting strategies towards hepatocytes stems from the lack of
efficient therapeutic options to treat numerous serious liver diseases. Moreover, various
genetic disorders, such as α1-antitrypsin deficiency and hemophilia A and B, are depending
on an efficient gene delivery to defined cells, such as hepatocytes, preferentially avoiding
viral vectors. Since the asialoglycoprotein receptor is primarily expressed by liver
parenchymal cells, it offers a potential target for a cell specific delivery system.
First, the binding of various vectors was analyzed, using the human hepatocellular carcinoma
cell line HepG2 as an in vitro model. While the uptake of D-galactose as a monomer was
non-specific, the glycoprotein asialofetuin was analyzed as an alternative vector, which
represents the desialated derivative of fetuin, containing multi-antennary galactose-
terminating glycan residues. Next to a pronounced cellular accumulation, the uptake was
markedly inhibited in the presence of an excess of free asialofetuin, indicating specific
endocytosis through the asialoglycoprotein receptor. Therefore, asialofetuin was selected as
an ideal vector for the further development of a drug delivery system targeting liver
parenchymal cells.
Asialofetuin was covalently attached to pegylated liposomes, yielding a highly monodisperse
preparation with a particle size below 100 nm. A subsequently incubation with HepG2 cells
resulted in a specific endocytosis of the vesicles, providing an experimental proof of concept
for targeting hepatocytes in vitro. The delivery and intracellular accumulation in HepG2 cells
were investigated by incorporating various organic dyes and fluorescent semiconductor
nanocrystals, also known as quantum dots, into liposomes. The cellular uptake of
asialofetuin-conjugated liposomes, loaded with quantum dots, resulted in a bright fluorescent
signal, which was impaired by the need for a specific photoactivation prior to fluorescence
analysis. Despite their challenging optical properties, quantum dots are valuable
fluorochromes for further optimization of drug targeting strategies.
Finally, a proof of principle for a hepatocyte specific delivery was provided in vivo, by
intravenously injecting rats with asialofetuin-conjugated and pegylated liposomes, which
were taken up by the liver parenchymal cells. In contrast, accumulation in hepatocytes was
reduced by co-injecting free asialofetuin and conventional liposomes were uniquely engulfed
by Kupffer cells.
Summarized, asialofetuin-conjugated pegylated liposomes represent a novel approach,
combining desialated glycoproteins, which exhibit a high affinity towards the
asialoglycoprotein receptor, with long circulating vesicles, for a specific targeting of liver
parenchymal cells. This concept represents a most promising strategy for a hepatocyte
specific drug delivery system and gives the opportunity for further studies, such as the
isolated utilization of glycans only, to avoid immunogenic reactions.
These targeting strategies can be used to deliver drugs to diseased tissues or organs within
our body. This reflects our interests to modulate the pharmacokinetics of drugs using specific
formulation strategies. Two additional pharmacokinetic investigations of pharmaceutical
relevant substances were published in peer-reviewed journals. One study addresses the risk
of physical drug interactions of ceftriaxone with calcium in human plasma, and the second
one discusses the interaction potential of high doses of resveratrol with various cytochrome
P450 isoenzymes. These studies are presented in the section “Appendix”, to separate them
from the drug targeting approach of hepatocytes using liposomal formulations
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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