1,721,002 research outputs found
Nanoparticulate devices for brain drug delivery.
No full textThe blood-brain barrier (BBB) limits the transport of therapeutic molecules from the blood compartment into the brain, thus greatly reducing the species of therapeutic compounds that can be efficiently accumulated in the central nervous system (CNS). Various strategies have been proposed for improving the delivery of drugs to this tissue, and numerous invasive and noninvasive methods have been proposed by different scientists in an attempt to circumvent the BBB and to increase the delivery of drug compounds into the brain. An interesting alternative, in the solution of this problem and also that of reaching a suitable target in the CNS, has recently been provided through the use of nanoparticulate colloidal devices as a noninvasive technique for brain drug delivery. These systems offer diverse advantages over invasive strategies, because (1) they are designed using biocompatible and biodegradable materials; (2) they avoid the disruption and/or modification of the BBB; and (3) they modulate the biopharmaceutical properties of the entrapped drugs. Moreover, the possibility of targeting specific brain tissue, thanks to ligands linked to the surface of the nanoparticulate colloidal devices, confers the necessary characteristics for the treatment of CNS pathologies to these drug carriers. The aim of this review is to focus on describing the main strategies in use for designing nanoparticulate colloidal devices for CNS delivery, their potentiality as noninvasive strategies in the delivery of drugs to the cerebral tissues, and their biological and clinical applications in cerebral drug delivery
Gemcitabine-loaded innovative nanocarriers vs GEMZAR: biodistribution, pharmacokinetic features and in vivo antitumor activity.
No full textINTRODUCTION: Gemcitabine, an anticancer drug, is a nucleoside analog deoxycytidine antimetabolite, which acts against a wide range of solid tumors. The limitation of gemcitabine is its rapid inactivation by the deoxycytidine deaminase enzyme following its in vivo administration. AREAS COVERED: One of the most promising new approaches for improving the biopharmaceutical properties of gemcitabine is the use of innovative drug delivery devices. This review explains the current status of gemcitabine drug delivery, which has been under development over the past 5 years, with particular emphasis on liposomal delivery. In addition, the use of novel supramolecular vesicular aggregates (SVAs), polymeric nanoparticles and squalenoylation were treated as interesting innovative approaches for the administration of the nucleoside analog. EXPERT OPINION: Different colloidal systems containing gemcitabine have been realized, with the aim of providing important potential advancements through traditional ways of therapy. A possible future commercialization of modified gemcitabine is desirable, as was true in the case of liposomal doxorubicin (Doxil(®), Caely(®))
Supramolecular devices to improve the treatment of brain diseases.
No full textThe blood-brain barrier (BBB) hinders the accumulation of active compounds in the central nervous system, thus decreasing their therapeutic effectiveness. To overcome this obstacle, interesting supramolecular nanodevices are herein considered. These systems have many advantages over the conventional formulations, such as having structures made up of biocompatible and biodegradable materials, the possibility of bypassing the BBB in a non-invasive manner (without structural modifications) and the possibility of being structurally modified to modulate the biopharmaceutical properties of the encapsulated compounds. Polymolecular (liposomes, niosomes, nanogels) and oligomolecular (cyclodextrins) devices have potential clinical applications in brain drug delivery, being capable of active targeting that can concentrate bioactives in the brain
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
Gemcitabine and tamoxifen-loaded liposomes as multidrug carriers for the treatment of breast cancer diseases
No full textThe effects of a lipid composition on the physico-chemical and technological properties of a multidrug carrier (MDC) containing both gemcitabine (GEM) and tamoxifen (TMX), as well as its in vitro antitumoral activity on different breast cancer cell lines, were investigated. In particular, the following three different liposomal formulations were prepared: DPPC/Chol/DSPE-mPEG2000 (6:3:1 molar ratio, formulation A), DPPC/Chol/DOTAP (6:3:1 molar ratio, formulation B) and DPPC/Chol/DPPG (6:3:1 molar ratio, formulation C). The colloidal systems were obtained by the TLE technique and the extrusion process allowed us to obtain vesicles having mean sizes of 150-200 nm, while the surface charges varied between 50 mV and -30 mV. Formulation A showed the best encapsulation efficiency between the two compounds and the presence of TMX influenced the release profile of GEM (hydrophilic compound) as a consequence of its effect on the fluidity of the bilayer. An MDC of formulation A was used to effectuate the in vitro cytotoxicity experiments (MTT-test) on MCF-7 and T47D cells. The liposomal MDC provided the best results with respect to the single drug tested in the free form or entrapped in the same liposomal formulation. The CLSM experiments showed a great degree of cell interaction of liposomal MDC after just 6 h
Polyaspartylhydrazide copolymer-based supramolecular vesicular aggregates as delivery devices for anticancer drugs
No full textIn this paper we report on three different hydrophilic copolymers based on R,-polyaspartylhydrazide
(PAHy) bearing butyric groups in the side chain (C4) (PAHy-C4) or a combination of butyric groups
and positive charged residues ((carboxypropyl)trimethylammonium chloride, CPTACl) (PAHy-C4-CPTA)
that were synthesized and used for the preparation of new supramolecular vesicular aggregates (SVAs)
containing gemcitabine as an antitumor drug. Gemcitabine-loaded SVAs containing synthesized PAHy
derivatives were characterized from the physicochemical and technological point of view and the in vitro
toxicity and anticancer activity on two different human cancer cell lines, i.e., CaCo-2 (human colon
carcinoma) and ARO (human anaplastic thyroid carcinoma) cells, were also evaluated. Moreover,
considering that carrier-cell interaction is an important factor to achieve an improvement of anticancer
drug activity, confocal laser scanning microscopy and flow cytometric experiments were carried out
on the two different cancer cell lines
Effects of lipid composition and preparation conditions on physical-chemical properties, technological parameters and in vitro biological activity of gemcitabine-loaded liposomes.
No full textThe effects of lipid composition and preparation conditions on the physicochemical and technological properties of gemcitabine-loaded liposomes, as well as the in vitro anti-tumoral activity of various liposome formulations were investigated. Three liposome formulations were investigated: DPPC/Chol/Oleic acid (8:3:1 molar ratio, liposomes A), DPPC/Chol/DPPS (6:3:1 molar ratio, liposomes B) and DPPC/Chol/DSPE-MPEG (6:3:1 molar ratio, liposomes C). Multilamellar liposomes were prepared by using the TLE, FAT and DRV methods, while small unilamellar liposomes were obtained by extrusion through polycarbonate filters. Light scattering techniques were used to characterize liposome formulations. Loading capacity and release profiles of gemcitabine from various liposome formulations were also investigated. Caco-2 cells were used to evaluate in vitro the antitumoral activity of gemcitabine-loaded liposomes with respect to the free drug and also the intracellular drug uptake. Preparation methods and liposome lipid composition influenced both physicochemical parameters and drug delivery features. Liposomes with a size ranging from 200 nm to 7 microm were obtained. The gemcitabine entrapment was higher than that expected probably due to an interaction with the liposome lipid components. The following decreasing loading capacity order was observed: liposome B>liposome C>liposome A. Gemcitabine release from various liposome formulations is modulated by two different processes, i.e. desorption from and permeation through liposomal bilayers. MTT assay showed a greater cytotoxic effect of gemcitabine-loaded liposomes with respect to the free drug. The following decreasing anticancer activity order was observed between the various liposome formulations: liposome C>liposome A>liposome B. The increased anticancer activity is correlated to the ability of the colloidal carrier to increase the intracellular drug uptake. Due to the encouraging results and to the high liposome modularity various applications of potential therapeutic relevance can be envisaged for liposomes
- …
