1,721,369 research outputs found
MicroRNA therapeutics: design of single-stranded miR-216b mimics to target KRAS in pancreatic cancer cells
Get PDFDatasets reporting microRNA expression profiles in normal and cancer cells show that miR-216b is aberrantly downregulated in pancreatic ductal adenocarcinoma (PDAC). We found that KRAS, whose mutant G12D allele drives the pathogenesis of PDAC, is a target of miR-216b. To suppress oncogenic KRAS in PDAC cells, we designed single-stranded (ss) miR-216b mimics with unlocked nucleic acid (UNA) modifications to enhance their nuclease resistance. We prepared variants of ss-miR-216b mimics with and without a 5' phosphate group. Both variants strongly suppressed oncogenic KRAS in PDAC cells and inhibited colony formation in pancreatic cancer cells. We observed that the designed ss-miR-216b mimics engaged AGO2 to promote the silencing of KRAS. We also tested a new delivery strategy based on the use of palmityl-oleyl-phosphatidylcholine (POPC) liposomes functionalized with ss-miR-216b conjugated with two palmityl chains and a lipid-modified cell penetrating peptide (TAT). These versatile nanoparticles suppressed oncogenic KRAS in PDAC cells
Modular Assembly of Cell-targeting Devices Based on an Uncommon G-quadruplex Aptamer
Get PDFAptamers are valuable tools that provide great potential to develop cost-effective diagnostics and therapies in the biomedical field. Here, we report a novel DNA aptamer that folds into an unconventional G-quadruplex structure able to recognize and enter specifically into human Burkitt's lymphoma cells. We further optimized this aptamer to a highly versatile and stable minimized version. The minimized aptamer can be easily equipped with different functionalities like quantum dots, organic dyes, or even a second different aptamer domain yielding a bi-paratopic aptamer. Although the target molecule of the aptamer remains unknown, our microscopy and pharmacological studies revealed that the aptamer hijacks the clathrin-mediated endocytosis pathway for its cellular internalization. We conclude that this novel class of aptamers can be used as a modular tool to specifically deliver different cargoes into malignant cells. This work provides a thorough characterization of the aptamer and we expect that our strategy will pave the path for future therapeutic applications
Aplicação de oligómeros de antisense para prevenir infeções por Candida albicans
No full textTese de doutoramento em Chemical and Biological EngineeringCandida albicans is the main cause of candidiasis and its pathogenicity is supported by a series of virulence factors, including the switch from yeast to filamentous forms. The transcription factor EFG1 plays a central role in C. albicans regulation morphology. In addition, there is rise of C. albicans multidrug resistance accompanied by the scarcity of new classes of fungal drugs. Antisense oligonucleotides (ASOs) can hold great promise as a therapeutic agent, however yet they are poorly explored for controlling Candida infections. Therefore, the main goal of this work was to develop a therapeutic approach based on antisense therapy (AST) to track C. albicans filamentation. To this end, two major objectives were addressed: I) Exploitation and application of ASOs to control C. albicans filamentation; II) Creation of strategies for ASOs cargo and delivery.
The first goal of this research was the exploitation of the second and third generations of ASOs to control EFG1 gene and C. albicans filamentation. To this end, the anti-EFG1 2’OMethylRNA was firstly projected based on second generation of ASOs and was proved to have an impact on the reduction of EFG1 gene expression (by 60 %) and on Efg1p protein translation (by 60 %). Interestingly, the ASO was able to inhibit filamentation and to attenuate the virulence of C. albicans on in vivo Galleria mellonella (increasing its survival on 30 % at 72h with a double-dose administration). Based on the third generation of ASOs, a set of anti-EFG1 LNA (Locked nucleic acids) ASOs were developed, and their performance was tested in vitro and in vivo. All LNA-ASOs were able to reduce EFG1 gene expression (by 40-80 %) and consequently filamentation (by 45-55 %) in vitro. The in vivo results revealed that the LNA-ASO modified with PS-linkages and palmitoyl-2’-amino-LNA as the most favorable for an in vivo application (increasing G. mellonella survival by 40 % only with a single-dose administration).
The second goal of this research was the development of strategies for anti-EFG1 ASO cargo and delivery. Two distinct approaches were tested: (i) development of polyplexes based on polyamide 4 and 6, that revealed to be feasible carriers, once the ASO maintains its activity against C. albicans cells; (ii) application of lipid-based formulations, where the DOTAP/DOPC 80/20 ρ=3 revealed to be the most promising when tested in a G. mellonella model (25 % of increase on larvae survival in comparison to ASO-free at 72 h).
In summary, this research underlines the therapeutic potential of ASOs for controlling C. albicans virulence determinants, as is the case of EFG1 gene, as well as the importance of developing carriers’ systems for ASOs cargo. Considering the future research into the management of C. albicans infections, this research provides valuable information to the development of a credible and alternative method to control C. albicans infections, based on AST.Candida albicans é uma das principais causas de candidíase e a sua patogenicidade é suportada por um conjunto de fatores de virulência, incluindo a capacidade de filamentar. EFG1 é um fator de transcrição com papel fundamental na filamentação. O aumento da multirresistência de C. albicans é acompanhado pela escassez de novos antifúngicos. Os oligonucleotídeos de antisense (OAS) têm revelado potencial como agentes terapêuticos, contudo ainda pouco explorados no controlo da candidíase. Assim, o principal objetivo deste trabalho foi desenvolver uma abordagem terapêutica baseada na Terapia Antisense (TA) para controlar a filamentação de C. albicans. Para tal, dois grandes objectivos complementares foram definidos: I) Exploração e aplicação de OAS para controlar a filamentação e II) Criação de estratégias para o transporte e entrega dos OASs.
Como primeiro objetivo explorou-se a segunda e terceira gerações de OASs para controlar o gene EFG1. O anti-EFG1 2’OMethylRNA foi projetado com base na segunda geração, e provou ter um impacto na redução da expressão do gene EFG1 (em 60 %) e na tradução da proteína Efg1p (em 60 %). O OAS foi capaz de inibir a filamentação e atenuar in vivo a virulência de C. albicans em Galleria mellonella (30 % de aumento de sobrevivência às 72 h após dupla administração). Por outro lado, um conjunto de OAS modificados com LNA (terceira geração) foram desenvolvidos e testados in vitro e in vivo. In vitro, os OAS-LNA inibiram a expressão do gene de EFG1 (em 40-80 %) e a filamentação (em 45-55 %). In vivo, o OAS-LNA com as modificações de PS e palmitoyl-2’amino-LNA revelou ser o mais favorável (40 % de aumento de sobrevivência da G. mellonella com uma administração).
Como segundo objetivo exploraram-se poliplexos e lipoplexos como estratégias para o transporte e entrega do anti-EFG1 2’OMe. Como primeira abordagem, desenvolveram-se poliplexos à base de poliamida 4 e 6, que revelaram ser veículos viáveis, uma vez que o OAS manteve a sua atividade contra as células de C. albicans. Em seguida, foram exploradas formulações lipídicas, sendo que o DOTAP/DOPC 80/20 ρ=3 revelou ser a mais promissora quando testada in vivo (25 % de aumento de sobrevivência da G. mellonella em comparação com o OAS livre às 72 h).
Em suma, esta investigação destaca o potencial terapêutico de OAS para o controlo de determinantes de virulência de C. albicans, como o caso do gene EFG1, bem como a importância do desenvolvimento de sistemas de veículos para o seu transporte. Considerando futuros trabalhos sobre o controlo de infeções por C. albicans, esta investigação fornece informação valiosa para o desenvolvimento de um método credível e alternativo para o controlo destas infeções, com base na TA.This work was supported by the Portuguese Foundation for Science and Technology (FCT) through the PhD
grant SFRH/BD/121417/2016 and the strategic funding of UIDB/04469/2020 unit and BioTecNorte
operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte. This study was also supported by the project funding by the “02/SAICT/2017 – Projetos de Investigação Científica e Desenvolvimento Tecnológico (IC&DT) – POCI-01-0145-FEDER-028893”, designated as Antisen4CandiB - Application of antisense oligomers for controlling Candida species biofilm formation on medical surfaces”
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
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
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