1,721,603 research outputs found
Bacteriophage control of infectious biofilms
Get PDFBiofilm formation, a strategy of bacterial survival, is a significant concern in different areas, including health, where infectious biofilms are very difficult to combat with conventional antimicrobial therapies. Bacteriophages, the viruses that infect bacteria, are promising agents to prevent and control biofilm-related infections. This chapter describes a series of standard procedures that can be used to study the potential of bacteriophages for biofilm control, from biofilm formation to bacteriophage treatment and evaluation of its efficacy
Exploiting Bacteriophage Proteomes: The Hidden Biotechnological Potential
No full textBacteriophages encode many distinct proteins for the successful infection of a bacterial host. Each protein plays a specific role in the phage replication cycle, from host recognition, through takeover of the host machinery, and up to cell lysis for progeny release. As the roles of these proteins are being revealed, more biotechnological applications can be anticipated. Phage-encoded proteins are now being explored for the control, detection, and typing of bacteria; as vehicles for drug delivery; and for vaccine development. In this review, we discuss how engineering approaches can be used to improve the natural properties of these proteins and set forth the most innovative applications that demonstrate the unlimited biotechnological potential held by phage-encoded proteins.Accepted Author ManuscriptBN/Stan Brouns La
Revisiting phage therapy: new applications for old resources
No full textThe success of phage therapy is dependent on the development of strategies able to overcome the limitations of bacteriophages as therapeutic agents, the creation of an adequate regulatory framework, the implementation of safety protocols, and the acceptance by the general public. Many approaches have been proposed to circumvent phages intrinsic limitations but none have proved to be completely satisfactory. In this review we present the major hurdles of phage therapy and the solutions proposed to circumvent them. A thorough discussion on the advantages and drawbacks of these solutions is provided and special attention is given to genetic modification of phages as an achievable strategy to shape bacteriophages to exhibit desirable biological properties.The authors thank the FCT Strategic Project PEst-OE/EQB/LA0023/2013 and the Project 'BioHealth - Biotechnology and Bioengineering approaches to improve health quality, Ref. NORTE-07-0124-FEDER-000027' cofunded by the Programa Operacional Regional do Norte (ON.2 - O Novo Norte), QREN, and FEDER. F.L.N. also acknowledges the FCT for grant SFRH/BD/86462/2012
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
Use of bacteriophages to control Campylobacter in poultry
No full textTese de doutoramento em Engenharia Química e BiológicaRecent publications indicate that Campylobacter is the leading cause of foodborne
diseases worldwide, clearly surpassing other foodborne pathogens such as Salmonella. Poultry
meat is regarded as the most common source of human campylobacteriosis, being
Campylobacter jejuni and Campylobacter coli the most prevalent species. Measures
commonly used to control foodborne pathogens have had little success for Campylobacter,
which is a reflection of differences in the physiology, epidemiology and ecology of these
organisms. Moreover, recent legislation restricting the use of antibiotics as growth promoters
in animal production, together with the risk of antibiotic-resistant bacteria entering the human
food chain, highlight the importance of finding alternative ways to control and treat animal
infection.
Bacterio(phages) are naturally occurring predators of bacteria, ubiquitous in the
environment, with high host specificity and capacity to evolve to overcome bacterial
resistance. These characteristics make phages an appealing option to control bacterial
pathogens.
The present study exploits phages as biocontrol agents to reduce the levels of
Campylobacter jejuni and Campylobacter coli in broilers and thus preventing this pathogen for
entering the human food chain. In order to accomplish this aim, Campylobacter phages were
isolated and characterized and three phages considered the best candidates for therapy were
selected for composing a phage cocktail that was further tested in animal trials.
This work presented several challenges mostly related to the fastidious growth of
Campylobacter and to unique features that Campylobacter phages exhibit, hindering the use of
conventional methods of phage isolation, propagation and characterization. Therefore these methods had to be adapted, optimized and implemented. One of the main achievements was
the development of a novel method to isolate Campylobacter phages that allowed the isolation
of 43 phages from poultry intestines. From this collection, three phages (phiCcoIBB12,
phiCcoIBB35, phiCcoIBB37) were selected based on the best performance in vitro and the
broadest lytic spectra against both Campylobacter jejuni and Campylobacter coli strains.
The selected phages were further characterized in terms of morphology and
physiology, showing to belong to the Myoviridae family of lytic phages. The DNA of one of
the selected phages (phiCcoIBB35) was sequenced and analyzed, contributing to deepen the
knowledge of Campylobacter phage genomes, since only two Campylobacter phage genomes
have been reported so far. The DNA sequence data of phiCcoIBB35 consists of five DNA
contigs in a total of 172,065 bp, being most of the open reading frames (ORFs) unique. It was
possible to identify the genes encoding for tail fibers and for the lytic cassette, this later
expressing enzymes involved in bacterial capsular polysaccharides (CPS) degradation, which
has never been reported before for Campylobacter phages.
The three selected and characterized phages were used to compose a cocktail that was
administered by oral gavage or on feed to one-day old Campylobacter infected chicks. The
results of the in-vivo phage performance evaluation revealed that both administration routes
enabled the same levels of Campylobacter reduction by approximately 2 log10 cfu/g, however,
feed incorporating phages resulted in an earlier Campylobacter reduction. This can be
considered a promising, effective and innovative approach of phage administration to be used
under commercial condition in a poultry unit.
Overall this work contributed for the improvement of knowledge of Campylobacter
phages biology, physiology, genomics and proteomics and established the proof-of-principle
that the administration of Campylobacter phages in living poultry can be an effective measure
to reduce the levels of Campylobacter colonization.Estudos recentes indicam que bactérias do género Campylobacter são as principais
causas de intoxicações alimentares em todo o mundo, superando claramente os principais
agentes patogénicos associados a infecções alimentares no passado, tal como a Salmonella. A
carne de aves é considerada a fonte mais comum da campilobacteriose humana, sendo
Campylobacter coli e Campylobacter jejuni as espécies mais predominantes. As várias
medidas postas em prática para o controlo da contaminação de alimentos por outras bactérias
têm sido geralmente mal sucedidas para Campylobacter, o que é um reflexo das diferenças na
fisiologia, epidemiologia e ecologia desses microrganismos. Além disso, a recente legislação
que restringe a utilização de antibióticos como promotores de crescimento na produção animal,
juntamente com o risco da transferência de bactérias resistentes aos antibióticos para a cadeia
alimentar, reforça a necessidade de formas alternativas de controlo e tratamento de infecções
em animais para consumo.
Os bacterió(fagos) são predadores naturais das bactérias, estão presentes no ambiente,
apresentam especificidade elevada para o hospedeiro e capacidade para evoluir superando a
resistência bacteriana. Estas características tornam os fagos uma opção bastante atractiva no
controlo de bactérias patogénicas.
O presente trabalho explora a utilização de fagos como agentes de biocontrolo para
reduzir os níveis de Campylobacter coli e Campylobacter jejuni em frangos evitando, desta
forma, a entrada desta bactéria na cadeia alimentar humana. Para atingir esse objectivo, foi
necessário o isolamento e a caracterização de fagos de Campylobacter e a selecção de três
fagos considerados os melhores candidatos para terapia, que posteriormente constituíram o
cocktail usado nos ensaios in vivo. Este trabalho apresentou vários desafios científicos, na sua maioria relacionados com o
crescimento fastidioso da bactéria Campylobacter e com as características únicas que os fagos
de Campylobacter apresentam, o que impossibilitou o uso directo de métodos convencionais
de isolamento, caracterização e propagação de fagos em geral. Neste sentido, os métodos
convencionais tiveram que ser adaptados, aperfeiçoados e implementados. Um dos principais
resultados foi o desenvolvimento de um novo método de isolamento de fagos de
Campylobacter, que permitiu isolar 43 fagos a partir dos intestinos de aves. Os três fagos
seleccionados (phiCcoIBB12, phiCcoIBB35, phiCcoIBB37) com base no melhor desempenho
in vitro e espectro lítico alargado contra estirpes de Campylobacter coli e Campylobacter
jejuni, foram caracterizados em termos de morfologia e fisiologia, mostrando pertencer à
família Myoviridae. No presente estudo, o DNA de um dos fagos seleccionados
(phiCcoIBB35) foi sequenciado, o que permitiu aumentar o conhecimento do genoma de fagos
líticos de Campylobacter, uma vez que até à data só tinham sido descritos dois genomas. Os
dados da sequência do DNA de phiCcoIBB35 consistem em cinco fragmentos de DNA num
total de 172,065 bp sendo a maioria das ORFs (do inglês, Open Reading Frames) únicas e
homólogas aos membros da Teequatrovirinae. Também foi possível identificar os genes que
codificam para as fibras da cauda, e para a cassete lítica que expressa enzimas de degradação
dos polissacarídeos capsulares bacterianos (CPS), o que nunca tinha sido relatado antes para
fagos de Campylobacter.
Os três fagos seleccionados e caracterizados foram incorporados num cocktail que foi
administrado por via oral ou através da alimentação a frangos de um dia de idade, infectados
com Campylobacter. Ambas as formas terapêuticas permitiram os mesmos níveis de redução
de Campylobacter (cerca de 2 log10 cfu/g), mas a incorporação dos fagos no alimento resultou
numa redução mais rápida. Assim, pôde concluir-se que a administração de fagos de
Campylobacter na ração constitui uma abordagem inovadora, promissora e eficaz no controlo
de Campylobacter coli e Campylobacter jejuni em aves.
Em suma, este estudo contribuiu para o aumento do conhecimento da biologia,
fisiologia, genómica e proteómica de fagos de Campylobacter e estabeleceu o “proof-ofprinciple”
de que a administração de fagos de Campylobacter em aves pode ser considerada
uma medida eficaz para reduzir os níveis de colonização de Campylobacter.European Commission - FP-6-2003, Food-2-A to the
project 2005-7224 for the financial support and the Portuguese Foundation for Science
and Technology (FCT) through the grant SFRH/BD/23484/2005Fundação para a Ciência e a Tecnologia (FCT) bolsa SFRH/BD/23484/200
HACCP validation plan in the dinning hall, cafeteria and kitchen of Braga Hospital: corrective actions measures
No full textDissertação de mestrado integrado em Engenharia Biológica (área de especialização em Tecnologia Química Alimentar)Nos dias de hoje, uma das maiores preocupações públicas é a segurança alimentar. É
essencial garantir que os alimentos servidos no sector da restauração são seguros, visto que
se os fatores de risco envolvidos não forem controlados, pode tornar-se um problema de
saúde pública. O sistema HACCP é uma ferramenta fundamental para garantir os critérios de
segurança alimentar.
O presente trabalho teve como objetivo validar o sistema HACCP (PCC’s e PPRO’s) numa
empresa de restauração coletiva, a Gertal, no sentido de demonstrar que o sistema em
questão permite obter produtos alimentares seguros.
O presente estudo foi realizado na Unidade Hospital de Braga, onde o consumidor final
pode variar entre colaboradores saudáveis até doentes internados com grande debilidade
física. Assim sendo é muito importante garantir a qualidade e segurança dos produtos
alimentares. Para validar o sistema, validando vários PCC’s/PPRO’s abrangidos no plano de
validação da empresa, foi realizado um estudo microbiológico sentido de verificar se os
alimentos derivados de cada etapa/processo estavam seguros para o seu consumo final.
No decurso do trabalho aqui apresentado, realizaram-se 30 análises microbiológicas a
alimentos superfícies e utensílios, das quais 29 estavam conformes e uma delas nãoconforme.
No caso da análise em que os critérios não estavam em conformidade
implementaram-se as medidas corretivas e realizou-se uma nova análise, obtendo-se
resultados positivos. Neste sentido validou-se o sistema HACCP da empresa. Os
procedimentos de segurança alimentar estabelecidos pela Gertal garantem a segurança dos
produtos alimentares servidos no Hospital de Braga.Nowadays, one of the biggest public concerns is food security. It is essential to ensure that
the food served in the restaurant sector is safe, since if the risk factors involved are not controlled,
that can become a public health problem. The HACCP system is a fundamental tool
to ensure food safety criteria.
The objective of this study was to validate the HACCP (PPRO's and CCP's) system in a catering
company, the Gertal, to demonstrate that the system in question allows for secure food
production.
The study was conducted in the Hospital Unit of Braga, where the final consumer can be
either healthy collaborators or hospitalized patients with major physical weaknesses. Thus,
it is very important to guarantee the quality and safety of food products.
To validate the system, by validating the various CCP’s / PPRO's included in the company’s
validation plan, a microbiological study was carried out in order to verify whether the food
produced in each stage/process was safe for final consumption.
During the work presented here, there were 30 microbiological analyses on food, surfaces
and utensils, from which 29 were compliant and one was non-compliant. In this case,
where the quality criteria were not verified, corrective actions were implemented and a new
analysis was performed, obtaining positive results. Thus, the HACCP system was validated.
The safety procedures established by the Gertal company ensure the safety of the food
products served in the Braga Hospital
Phage therapy applied to chronic lung infections: development and monitoring of therapeutic protocols
Get PDFDissertação de mestrado em Biomedical Engineering, Clinical Engineering BranchO aumento da resistência das bactérias aos antibióticos apresenta-se atualmente como uma das
maiores preocupações na área da saúde a nível mundial. Desta forma, torna-se necessário encontrar
alternativas para o tratamento de infeções causadas por bactérias multirresistentes, para as quais as
opções convencionais já não são suficientes. O uso de bacteriófagos surge como uma dessas
alternativas, sendo uma opção cada vez mais explorada. No entanto, a terapia fágica apresenta ainda
muitos obstáculos na sua implementação, nomeadamente questões regulamentares e incertezas
relacionadas com a eficácia e segurança desta abordagem. Assim, torna-se fundamental obter validação
científica com o objetivo de estabelecer a terapia fágica como uma prática terapêutica de rotina. O
trabalho desenvolvido no âmbito desta dissertação teve como objetivo contribuir para a implementação
da terapia fágica em Portugal.
Desta forma, estabeleceram-se e uniformizaram-se protocolos terapêuticos que devem ser
seguidos em terapia fágica, nomeadamente foi realizada a padronização dos protocolos relativos a
fagogramas, isolamento, caracterização e adaptação de fagos. O uso destes protocolos permitiu
padronizar e facilitar os procedimentos laboratoriais executados em casos clínicos. Além disso,
estabeleceu-se o protocolo de colaboração existente entre Portugal e a Bélgica que permitiu o tratamento
de doentes portugueses segundo a fórmula magistral belga.
Simultaneamente, foi feito o acompanhamento de diferentes pacientes que decidiram recorrer à
terapia fágica. Numa primeira fase, foi feita a identificação de fagos ativos contra os isolados clínicos dos
pacientes. Alguns desses pacientes foram tratados com fagos, sendo que os mesmos reportaram
melhorias significativas após o tratamento. Adicionalmente, foi realizado o isolamento de novos fagos
nos casos em que não foi possível identificar fagos ativos. Além disso, foi realizada uma caracterização
mais completa da população bacteriana antes e após o tratamento com fagos em dois pacientes com
infeção crónica respiratória provocada por Pseudomonas aeruginosa. Apesar da necessidade de mais
estudos para consolidar as evidências científicas sobre a eficácia da terapia fágica, os resultados obtidos
neste trabalho indicam um início promissor.
Assim, os avanços obtidos representam um passo significativo para a viabilidade deste tipo de
tratamento no contexto nacional. O trabalho realizado estabelece uma base sólida para futuras
investigações e, possivelmente, para a aplicação mais ampla desta abordagem terapêutica em Portugal.The increase in bacterial resistance to antibiotics is currently one of the biggest health concerns
worldwide. Therefore, it is necessary to find alternatives for the treatment of infections caused by multi resistant bacteria, for which conventional options are no longer sufficient. The use of bacteriophages has
emerged as one of these alternatives and is an increasingly explored option. However, phage therapy still
presents many obstacles in its implementation, namely regulatory issues and uncertainties related to the
efficacy and safety of this approach. Thus, it is fundamental to obtain scientific validation with the objective
of establishing phage therapy as a routine therapeutic practice. The work developed within the scope of
this dissertation aimed to contribute to the implementation of phage therapy in Portugal.
To this end, this work included establishment and standardization of therapeutic protocols that
should be followed in phage therapy, namely the harmonization of protocols relating to phagograms,
isolation, characterization and adaptation of phages. The use of these protocols made it possible to
standardize and facilitate the laboratory procedures performed in clinical cases. In addition, the
collaboration protocol between Portugal and Belgium was established, which allowed Portuguese patients
to be treated using the Belgian magistral formula.
Simultaneously, different patients who decided to resort to phage therapy were accompanied.
Initially, phages active against the patients' clinical isolates were identified. Some of these patients were
treated with phages and reported significant improvements after treatment. In addition, the isolation of
new phages was performed in cases where it was not possible to identify active phages. Furthermore, a
more complete characterization of the bacterial population was carried out before and after treatment
with phages in two patients with chronic respiratory infection caused by Pseudomonas aeruginosa.
Despite the need for further studies to consolidate the scientific evidence on the efficacy of phage therapy,
the results obtained in this study indicate a promising beginning.
Thus, the advances made represent a significant step towards the viability of this kind of
treatment in the national context. The work carried out establishes a solid basis for future research and,
possibly, for the wider application of this therapeutic approach in Portugal
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