1,720,971 research outputs found
Improving bioavailability of insoluble payloads through PLGA nanotechnology
Get PDFBioactive molecules are a cluster of natural or synthetic compounds, which modu- late actions in the body promoting good health. Furthermore, they have been ap- plied in the prevention of cancer, heart disease, and other diseases for their antiox- idant, anti-inflammatory, anti-microbial, anti-cancer properties. Among them, many are hydrophobic or poorly soluble nutrients, such as phenolic compounds, ca- rotenoids, essential oils, essential fatty acids, insoluble peptides, and vitamins. Their low water solubility is the limiting factor for their use in both nutraceutical and pharmacological industries. In fact, drugs with poor water solubility show a slower absorption rate, which can lead to inadequate bioavailability making the drug ineffective. Furthermore, hydrophobic molecules can also be used as bio- probe for imaging purpose. Narrow bandwidth emissions and large Stokes shifts make lanthanide complexes interesting as versatile molecular probes of biological systems. Nevertheless, they are not widely used for imaging purpose since their luminescence is completely quenched in aqueous environment. In this scenario, nanoencapsulation through the use of polymeric nanoparticles (NPs ) could be an effective solution to improve solubility and protection of the insoluble payload with consequent increase in bioavailability and action. Poly lac- tic-co-glycolic acid (PLGA) is a synthetic copolymer of lactic acid and glycolic acid of remarkable interest for potential applications in biomedicine; indeed, for its biodegradability and biocompatibility, it has been approved for human use both by Food and Drug Administration (FDA) and European Medicine Agency (EMA). In this thesis, we want to give several proofs of concept about the huge potentiality of PLGA nanoparticles in medical purpose. We used single emulsion methos (O/W) to encapsulate natural bioactive molecules producing planted-derived PLGA nanocarriers enabling anti-inflammatory and antioxidant activity when the polyphe- nol Oxyresveratrol has been incorporated into PLGA NPs. Moreover, an osteogenic promoting action has been observed when PLGA NPs have been embedded with Fisetin (a natural flavonoid).Since PLGA can deliver more than one payload simultaneously, we also produced PLGA nanoassemblies able to combine antibacterial activity with physical treat- ments (such as magnetic and photothermic hyperthermia). Finally, we exploited the shielding properties of PLGA to preserve the luminescence of NIR-emitting lantha- nide complexes in aqueous environment. Therefore, we produced a NIR-CPL probe based on PLGA for bioassay imaging. To summarise, during the past three years we were able to use PLGA encapsulation technology to make natural or synthetic compounds bioavailable, even if naturally water insoluble, and use the loaded nanomaterials in in-vitro experiments assessing the activity of the encapsulated material, paving the way for their application in in- vivo tests and eventual use in nanomedicine
Efficiency of Chitosan Nanocarriers in Vaccinology for Mucosal Immunization
Get PDFThe mucosal barrier constitutes a huge surface area, close to 40 m2 in humans, located mostly in the respiratory, gastrointestinal and urogenital tracts and ocular cavities. It plays a crucial role in tissue interactions with the microbiome, dietary antigens and other environmental materials. Effective vaccinations to achieve highly protective mucosal immunity are evolving strategies to counteract several serious diseases including tuberculosis, diphtheria, influenzae B, severe acute respiratory syndrome, Human Papilloma Virus infection and Acquired Immune Deficiency Syndrome. Interestingly, one of the reasons behind the rapid spread of severe acute respiratory syndrome coronavirus 2 variants has been the weakness of local immunization at the level of the respiratory mucosa. Mucosal vaccines can outperform parenteral vaccination as they specifically elicit protective mucosal immune responses blocking infection and transmission. In this scenario, chitosan-based nanovaccines are promising adjuvants-carrier systems that rely on the ability of chitosan to cross tight junctions and enhance particle uptake due to chitosan-specific mucoadhesive properties. Indeed, chitosan not only improves the adhesion of antigens to the mucosa promoting their absorption but also shows intrinsic immunostimulant abilities. Furthermore, by finely tuning the colloidal properties of chitosan, it can provide sustained antigen release to strongly activate the humoral defense. In the present review, we agnostically discuss the potential reasons why chitosan-based vaccine carriers, that efficiently elicit strong immune responses in experimental setups and in some pre-clinical/clinical studies, are still poorly considered for therapeutic formulations
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
Oxyresveratrol-Loaded PLGA Nanoparticles Inhibit Oxygen Free Radical Production by Human Monocytes: Role in Nanoparticle Biocompatibility
Get PDFOxyresveratrol, a polyphenol extracted from the plant Artocarpus lakoocha Roxb, has been reported to be an antioxidant and an oxygen-free radical scavenger. We investigated whether oxyresveratrol affects the generation of superoxide anion (O2 ) by human monocytes, which are powerful reactive oxygen species (ROS) producers. We found that oxyresveratrol inhibited the O2 production induced upon stimulation of monocytes with -glucan, a well known fungal immune cell activator. We then investigated whether the inclusion of oxyresveratrol into nanoparticles could modulate its effects on O2 release. We synthesized poly(lactic-co-glycolic acid) (PLGA) nanoparticles, and we assessed their effects on monocytes. We found that empty PLGA nanoparticles induced O2 production by resting monocytes and enhanced the formation of this radical in -glucan-stimulated monocytes. Interestingly, the insertion of oxyresveratrol into PLGA nanoparticles significantly inhibited the O2 production elicited by unloaded nanoparticles in resting monocytes as well as the synergistic effect of nanoparticles and -glucan. Our results indicate that oxyresveratrol is able to inhibit ROS production by activated monocytes, and its inclusion into PLGA nanoparticles mitigates the oxidative effects due to the interaction between these nanoparticles and resting monocytes. Moreover, oxyresveratrol can contrast the synergistic effects of nanoparticles with fungal agents that could be present in the patient tissues. Therefore, oxyresveratrol is a natural compound able to make PLGA nanoparticles more biocompatible
Oxyresveratrol Inhibits R848-Induced Pro-Inflammatory Mediators Release by Human Dendritic Cells Even When Embedded in PLGA Nanoparticles
Get PDFOxyresveratrol, a stilbene extracted from the plant Artocarpus lakoocha Roxb., has been reported to provide a considerable anti-inflammatory activity. Since the mechanisms of this therapeutic action have been poorly clarified, we investigated whether oxyresveratrol affects the release of the pro-inflammatory cytokines IL-12, IL-6, and TNF-α by human dendritic cells (DCs). We found that oxyresveratrol did not elicit per se the release of these cytokines, but inhibited their secretion induced upon DC stimulation with R848 (Resiquimod), a well-known immune cell activator en-gaging receptors recognizing RNA viruses. We then investigated whether the inclusion of ox-yresveratrol into nanoparticles promoting its ingestion by DCs could favor its effects on cytokine release. For this purpose we synthesized and characterized poly(lactic-co-glycolic acid) (PLGA) nanoparticles, and we assessed their effects on DCs. We found that bare PLGA nanoparticles did not affect cytokine secretion by resting DCs, but increased IL-12, IL-6, and TNF-α secretion by R848-stimulated DCs, an event known as “priming effect”. We then loaded PLGA nanoparticles with oxyresveratrol and we observed that oxyresveratrol-bearing particles did not stimulate the cytokine release by resting DCs and inhibited the PLGA-dependent enhancement of IL-12, IL-6, and TNF-α secretion by R848-stimulated DCs. The results herein reported indicate that oxyresveratrol suppresses the cytokine production by activated DCs, thus representing a good anti-inflammatory and immune-suppressive agent. Moreover, its inclusion into PLGA nanoparticles mitigates the pro-inflammatory effects due to cooperation between nanoparticles and R848 in cytokine release. Therefore, oxyresveratrol can be able to contrast the synergistic effects of nanoparticles with microorganisms that could be present in the patient tissues, therefore overcoming a condition unfavorable to the use of some nanoparticles in biological systems
Complexes of rare earth ions embedded in Poly(lactic-co-glycolic acid) (PLGA) nanoparticles: Characterization and spectroscopic study
No full textSeveral Eu(III) complexes [(Eu(L1)(tta)2(H2O)]∙CF3SO3, Eu(L2)(NO3)3 and Eu(L3) with L1 = N,N’-bis(2-pyridylmethylidene)-1,2-(R,R+S,S)-cyclohexanediamine, L2 = N, N’-bis(2-quinolylmethylidene)- 1,2-(R,R+S,S)-cyclohexanediamine, L3 N-quinolyl-N,N’,N’-trans-l,2-cyclohexylenediaminetriacetic acid and tta = 2-thenoyltrifluoroacetyl-acetonate] and one Y(III) complex [(Y(L1)(tta)2(H2O)]∙CF3SO3] have been embedded, with a different degree of efficiency, in Poly(lactic-co-glycolic acid) (PLGA) matrix by using two different composition [Poly(lactic(50%)-co-glycolic acid(50%), briefly PLGA 50:50 and Poly(lactic(75%)-co-glycolic acid(25%), briefly PLGA 75:25], giving nanoparticles characterized by a monodispersed distribution of the size (diameter around 200 nm). The [Eu(L1)(tta)2(H2O)]∙CF3SO3 shows the most efficient Eu(III) luminescence (ɸTot = 25%) when embedded in PLGA 75:25. The release of the complex over the time in aqueous buffered solution has been followed by means of the decrease of Eu(III) luminescence and it is faster upon increasing the temperature to 37°C, in particular for the PLGA 50:50 system, whose melting temperature (Tm) is lower (33°C) than both the Tm of PLGA 75:25 (38°C) and the basal one
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
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