1,721,187 research outputs found
Enhanced antinociceptive and anti-inflammatory effects of ibuprofen encapsulated in niosomal vesicles
No full textThe non-steroidal anti-inflammatory (NSAID) drug Ibuprofen (α-methyl-4-(2-methylpropyl)-benzeneacetic acid),
is widely used in the treatment of pain, fever and inflammatory diseases. As far as its analgesic actions,
ibuprofen inhibits the production of prostanoids, which mediate peripheral and central pain sensation, reducing
the threshold to stimulation of nociceptors and increasing their terminal membrane excitability [1]. Niosomes,
are unilamellar or multilamellar non-ionic surfactant vesicles. The main characteristic of these vesicles is their
capability of encapsulating both lipophilic and hydrophilic drugs; hydrophilic drugs are encapsulated in the core
of vesicles, while lipophilic drugs can be encapsulated into the lipophilic domain of the lipid bilayer [2]. In this
work, we evaluated the analgesic activity of subcutaneous injection (s.c) of ibuprofen loaded TW20Gly
niosomes (N-IBU), in comparison with free ibuprofen (IBU) in acute and chronic pain animal models.
In vivo anti nociceptive activities of Ibuprofen-loaded vesicles were preliminarily tested by performing the
writing and capsaicin screening assays. In writhing test, acetic acid as peripheral pain inducer was utilized.
Analgesic activity was determined by entering the reduction of the number of writhes after acetic acid injection.
In the early tested mice, a statistically significant reduction of writhes was observed only in IBU branch, whereas
in the late tested mice the strongest reduction was observed in N[IBU] treated mice. In capsaicin experiments,
in which mice were injected under the hind paw with capsacin, nociceptive activity was evaluated by measuring
the time spent by mice in licking the injected paw. N-IBU significantly decreased capsaicin-induced paw licking,
while IBU was ineffective. N-IBU also induced the strongest antinociceptive effects in Zymosan-induced
hyperalgesia test. N-IBU increased pain threshold also in a model of neuropathic pain i.e. chronic sciatic nerve
ligation, reducing hypealgesia and allodyia 2h after the treatment up to 4h. In the same conditions IBU did not
gave any significant effect.
We can conclude that the encapsulation of the drug into the niosomes significantly increases IBU analgesic
activity, promoting a long lasting action of this drug. Thus, we propose TW20Gly niosomes as a new and more
effective strategy to vehicle IBU to treat acute and chronic pain conditions.
_____________________________________
1. Brunton LL, Chabner BA, Knollman BC. Goodman & Gilman’s the pharmacological basis of therapeutics. 12th ed. New York: McGraw-
Hill Medical; 2011.
2. Di Marzio L, Marianecci C, Petrone M, Rinaldi F, Carafa M., Colloids Surf B Biointerfaces 2011, 82(1), 18
Hybrid niosome complexation in the presence of oppositely charged polyions
No full textWe have investigated the formation of complexes between negatively charged niosomal vesicles (hybrid niosomes), built up by dicethylphosphate [DCP], Tween 20 and Cholesterol, and three linear differently charged cationic polyions, such as alpha-polylysine, epsilon-polylysine, and polyethylvinylpyridinium bromide [PEVP], with two different substitution degrees. Our aim is to investigate the interaction mechanism between anionic-nonionic vesicles (hybrid niosomes) and linear polycations, characterizing the resulting aggregates in view of possible applications of these composite colloidal particles as vectors for multidrug delivery. In order to explore the aggregation behavior of the complexes and to gain information on the stability of the single niosomal vesicles within the aggregates, we employed dynamic light scattering (DLS), laser Doppler electrophoretic measurements, and fluorescence measurement techniques. The overall phenomenology is well described in terms of the re-entrant condensation and charge inversion behavior, observed in different colloidal systems. The aggregate size and overall charge depend on the charge ratio between vesicles and polyions, and the aggregates reach their maximum size at the point of charge inversion (re-entrant condensation). While the overall phenomenology is similar for all three polycations investigated, the stability and the integrity of the hybrid niosomal vesicles forming the aggregates strongly depend on the chemical structure of the polycations. The role of the polycations in the aggregation process is discussed by identifying specific interactions with the niosomal membrane, pointing out their importance for possible applications as drug delivery vectors
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
Polysaccharide hydrogels for modified release formulations
No full textHydrogels are three-dimensional, hydrophilic, polymeric networks, with chemical or physical cross-links, capable of imbibing large amounts of water or biological fluids. Among the numerous macromolecules that can be used for hydrogel formation, polysaccharides are extremely advantageous compared to synthetic polymers being widely present in living organisms and often being produced by recombinant DNA techniques. Coming from renewable sources, polysaccharides also have frequently economical advantages over synthetic polymers. Polysaccharides are usually non-toxic, biocompatible and show a number of peculiar physico-chemical properties that make them suitable for different applications in drug delivery systems. We review here a selection of the most important polysaccharides that have been studied and exploited in several fields related to pharmaceutics. Particular attention has been focused on the techniques used for the hydrogel network preparation, on the drug delivery results, on clinical applications as well as on the possible use of such systems as scaffolds for tissue engineering. © 2007 Elsevier B.V. All rights reserved
Non phospholipid vesicles for pulmonary glucocorticoid delivery
No full textIn the formulation of inhaled drugs for the treatment of asthma and chronic obstructive pulmonary disease (COPD), considerable attention has been devoted to new aerosol morphologies which can either enhance the local effect and/or increase the penetration through the mucus, secreted in bronchial inflammatory diseases. In diseases characterized by bronchial hypersecretion, lipophilic substances, such as corticosteroids, can be remarkably impeded in reaching their receptors, which are localized within the cytoplasm of bronchial epithelial cells. Vesicles consisting of one or more surfactant bilayers enclosing aqueous spaces, are of particular interest because they offer several advantages with regard to chemical stability, lower cost and availability of materials compared to conventional liposomes. With the purpose of carrying out research leading to an innovative formulation for lung delivery capable of permeating the mucous layer, beclomethasone dipropionate, clinically used for the treatment of asthma and COPD was entrapped in non-phospholipid vesicles. The composition provicing the highest entrapment efficiency was chosen. The vesicles obtained after jet nebulization were characterized by means of freeze-fracture microscopy and dynamic light scattering. The efficiency of this new drug delivery system was evaluated in vitro with simulated mucus by means of diffusion experiments (three compartment cell apparatus), Using 0.1% mucin gel-like dispersion as a barrier to drug permeat on. (C) 2004 Elsevier B.V. All rights reserved
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
- …
