Browsing by Issue Date, starting with "2013-12"
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- Giardia Duodenalis e Desnutrição Crónica em Crianças Menores de Cinco Anos de uma Região Rural da Guiné-BissauPublication . Centeno-Lima, Sónia; Rosado-Marques, Vitor; Ferreira, Filipa; Rodrigues, Ruben; Indenque, Benjamim; Camará, Idrissa; Sousa, Bruno; Aguiar, Pedro; Nunes, Baltazar; Ferrinho, Paulo[PT] Introdução: A desnutrição e as infecções por parasitas intestinais como Giardia duodenalis coexistem nas mesmas regiões geográficas, atingindo maiores prevalências em países em desenvolvimento. O ciclo da desnutrição e infecção implica que ambas as condições se podem agravar mutuamente e comprometer o crescimento e desenvolvimento das crianças, com especial relevância para as menores de cinco anos. O objectivo do presente estudo foi investigar a associação entre a desnutrição crónica e a infecção por G. duodenalis em crianças de uma comunidade rural da Guiné-Bissau.Material e Métodos: Realizou-se um estudo de caso-controlo que incluiu 109 crianças com idades entre os 0 e os 59 meses de uma comunidade rural da Guiné-Bissau. A avaliação antropométrica das crianças em estudo permitiu identificar 31 casos de desnutrição crónica (z-score estatura para a idade < -2) e 78 controlos (z-score estatura para a idade ≥ -2). Foi realizado exame microscópico de fezes para a detecção e identificação de G. duodenalis e de outros parasitas.Resultados: Foi detectada infecção por G. duodenalis em 29,0% (9/31) dos casos e 35,9% (28/78) dos controlos. Não foi encontrada associação entre a infecção por G. duodenalis e a desnutrição crónica nas crianças em estudo.Discussão e Conclusão: Os resultados obtidos mantêm em aberto o interesse em desenhar estudos que explorem esta associação em diferentes regiões e contextos epidemiológicos, apontando para a reflexão sobre a importância dos critérios de definição de desnutrição e concomitantemente da análise subsequente.
- Envelhecimento e Violência: resultados preliminares do inquérito telefónicoPublication . Gil, Ana Paula; Kislaya, Irina; Santos, Ana João; Nicolau, Rita
- Novel Mutations in pncA, Associated With Catalytic Centre, Might Be Related With PZA High Resistance ProfilePublication . Silva, Carla; Perdigao, João; Jordão, Luísa; Portugal, IsabelTuberculosis (TB) remains a serious health problem worldwide, and the greatest threat to TB control is the emergence of multidrug (MDR) Mycobacterium tuberculosis (Mtb) strains. Pyrazinamide (PZA) is an important first-line anti-TB drug. The emergence of isolates resistant to PZA, associated with MDR resistance, difficult TB treatment options. In order to evaluate mutations that might be responsible for PZA resistance, 30 clinical isolates collected in Lisbon Health Region, were screened for mutations in pncA, pyrazinamidase (PZase) coding gene, which convert the pro-drug PZA into its active form. We found 12 mutations in 23 resistant isolates. Among these mutations, six occurred in residues from catalytic centre or play an important role in PZase-PZA binding. We highlighted mutations that have never been described before: 3bp deletion (Del) at position 412, and 13 base par (bp) deletion between residues Ala146 and Gly150. The Del 412 3bp observed corresponds to entire deletion of Cys138 residue. Cys138 is a conserved residue in the active site, responsible for maintaining a functional conformation and is directly involved in drug donor binding. We also found a 13bp deletion between residues Ala146 and Gly150, resulting in a frameshift mutation plus four residues absence (Val147, Arg148, Asn149 and Gly150). There are no references for mutations in these residues, however it has been reported that residue Ala146 interacts with Cys138 to establish a functional folding. Evidences from mutational directed studies showed that amino acid substitution in catalytic centre residues produced some degree of conformational changes, but substitutions in Cys138 was associated with large folding alterations. Altogether, the results let us to hypothesize that the novel mutations presented might confer significant differences in protein folding. The loss of four amino acid residues plus frameshift near Ala146 residue could alter stability of PZase, and interfere with Cys138 normal interaction, resulting in a diminished PZase activity. Moreover, absence of the entire Cys138 residue would drastically alter the catalytic centre conformation, resulting not only in a different folding and reduction of protein stability but could also depleted PZase activity, and culminate with mycobacteria survival in the presence of PZA. Nevertheless, more studies are needed to evaluate the influence of such mutations in resistance to PZA.
- Identification of maternal uniparental isodisomy of chromosome 10 in a patient with mitochondrial DNA depletion syndromePublication . Nogueira, Célia; Sales Marques, Jorge; Nesti, Claudia; Azevedo, Luisa; Di Lullo, Martina; Meschini, M. Clara; Santorelli, Filippo; Vilarinho, Laura
- Validação de um método de cromatografia líquida de alta resolução (HPLC) para doseamento da vitamina D em géneros alimentícios. Aplicação do método em diferentes matrizes alimentaresPublication . Parreira, Diana; Dias, M. Graça; Serra, M.Celeste[PT] Resumo O objetivo deste trabalho foi o de realizar os ensaios de validação necessários à acreditação de um método analítico para determinação da vitamina D em matrizes alimentares. Após validação, o método foi aplicado a matrizes que incluíram papas infantis, iogurtes, cereais, leite, ovos e massas infantis. De forma a atingir este fim, foram otimizados procedimentos de tratamento das amostras e validado um método analítico baseado na norma europeia, EN 12821, o qual permitiu a determinação do teor em vitamina D através de cromatografia líquida de alta eficiência (HPLC) pelo método do padrão interno. De forma a quantificar a vitamina D na matriz alimentar, as amostras sofreram um processo de saponificação seguido de extração líquido-líquido, e por fim isolamento e concentração através de cromatografia de HPLC semi-preparativa em fase normal e, quantificação através de HPLC analítica em fase reversa a um comprimento de onda de 265 nm. De forma a validar o método de HPLC foram determinados os parâmetros de validação: precisão (repetibilidade e precisão intermédia), limite de deteção e de quantificação, recuperação e exatidão. Utilizando os resultados da validação, precisão intermédia e exatidão, foi determinada a incerteza do resultado da medição. A avaliação da incerteza total conduziu ao valor de 26%, para o nível de confiança de 95%. O teor em vitamina D nas amostras analisadas variou entre 0,28 μg/100 g e 22 μg/100 g. Os resultados da análise das amostras mostraram que 14% destas apresentavam valores superiores aos indicados nos respetivos rótulos e 43% valores inferiores aos rotulados. Tendo em considerações as porções definidas na rotulagem das amostras analisadas duas amostras ultrapassaram a dose diária recomendada (5 µg) se for consumida apenas uma porção (30 g). Os resultados obtidos permitiram concluir que o método validado é adequado para a determinação da vitamina D nas diversas matrizes analisadas.
- Nanomateriais manufaturados: novos desafios para a saúdePublication . Louro, Henriqueta; Borges, Teresa; Silva, Maria JoãoOs nanomateriais manufaturados (NM)apresentam propriedades físico-químicas específicas que lhes conferem caraterísticas mecânicas, óticas, elétricas e magnéticas únicas e vantajosas para aplicações industriais e biomédicas. Contudo, o desenvolvimento exponencial das nanotecnologias contrasta com a ainda insuficiente avaliação de risco para a saúde humana e para o ambiente, conduzindo a preocupações em termos de saúde pública. Esta revisão procura sintetizar o conhecimento atual sobre a toxicidade dos NM, identificar as lacunas ainda existentes e descrever o contributo da nanotoxicologia para o enquadramento regulamentar dos NM, de modo a garantir a sua utilização segura e a minimização dos riscos para a saúde pública.
- Genomic diversity of drug-resistant mycobacterium tuberculosis isolates in Lisbon Portugal: towards tuberculosis genomic epidemiologyPublication . Perdigão, João; Silva, Hugo; Machado, Diana; Macedo, Rita; Maltez, Fernando; Silva, Carla; Jordão, Luísa; Couto, Isabel; Mallard, Kim; Coll, Francesc; Hill-Cawthorne, Grant A; Pain, Arnab; Clark, Taane G; Viveiros, Miguel; Portugal, IsabelMultidrug- (MDR) and extensively drug resistant (XDR) tuberculosis (TB) present a challenge to disease control and elimination goals. Lisbon, Portugal, has a high TB incidence rate and, unusual and successful XDR-TB strains that are found in circulation for almost two decades. In the present study, 56 Mycobacterium tuberculosis isolates, mostly recovered in Lisbon, were genotyped by 24-loci Mycobacterial Interspersed Repetive Unit – Variable Number of Tandem Repeats (MIRU-VNTR) and the genomes sequenced using a next generation sequencing platform – Illumina HiSeq 2000. The genotyping data revealed three major clusters associated with MDR-TB (Lisboa3-A, Lisboa3-B and Q1), two of which associated with XDR-TB (Lisboa3-B and Q1). Whilst the genomic data contributed to elucidate the phylogenetic positioning of circulating MDR-TB strains, showing a high predominance of a single SNP cluster group 5. Furthermore, a genome-wide phylogeny analysis from these strains, together with 19 publicly available genomes of Mycobacterium tuberculosis clinical isolates, revealed two major clades responsible for M/XDR-TB in the region: Lisboa3 and Q1. On the overall, 9419 different SNPs were identified, ranging between 488 – 1465 per isolate (mean: 928 SNPs/isolate). The data presented by this study contributes to the expanding knowledge of Mycobacterium tuberculosis genomic diversity yielding insights on microevolution and identification of novel compensatory mutations associated with rifampicin resistance in rpoB and rpoC. The screening for other structural variations revealed putative clade-defining variants. One deletion in PPE41, found among Lisboa3 isolates, is proposed to contribute to immune evasion and as a selective advantage. Insertion sequence (IS) mapping has also demonstrated the role of IS6110 as a major driver in mycobacterial evolution by affecting gene integrity and regulation. A total of 251 candidate insertion sites were detected, of which 105 were intergenic and 64 were predicted to have a putative upregulatory effect. Additionally, the analysis of non-synonymous/synonymous ratios revealed heterogeneities across the chromosome, genotype and Clusters of Orthologous Groups, highlighting possible and different evolution strategies. Globally, our data supports the notion of a growing genomic diversity facing both setting and host adaptation.
- Exploring a link between pathogens structure's and resistance to disinfectantPublication . João, Inês; Reis, Lúcia; Carvalho, Patrícia; Duarte, Aida; Jordão, LuísaIn recent years healthcare-associated infections (HAIs) infections have gained growing importance. Among their etiological agents are classical (e.g. K. pneumoniae, S. aureus) and emergent pathogens, previously neglected, such as nontuberculous mycobacteria (NTM). The ability to resist to antibacterial agents, such as antibiotics and disinfectants, is shared by all of them. Here we aim to establish a link between bacterial virulence, disinfectant resistance and structure. Bacterial reference strains and clinical isolates were grown in adequate medium. NTM susceptibility test to antibiotics was evaluated by broth microdilution method and interpreted according to NCCLS guidelines in a previous work. The susceptibility to disinfectants (hydrogen peroxide, ammonium quaternary salts [AQS] and glutaraldehyde [GA]) was performed by two different methods: broth microdilution and diffusion in solid medium. In order to evaluate the effect of these agents in bacteria a scanning electron microscopy (SEM) study was performed. Hydrogen peroxide was the less effective disinfectant. The efficiencies of QAS and GA were similar. Nevertheless, among NTM we identified one isolate resistant to all disinfectants tested (Table 1). The SEM analysis showed that different disinfectants caused different effects on bacteria suggesting different action mechanisms (Figure 1). Bacterial resistance to antibiotics and disinfectants vary in the same manner. The mechanisms involved in the resistance are not fully elucidated and more studies are needed to provide effective conclusions. Biofilm formation can be part of the mechanism involved both in antibiotic/disinfectant resistance development and infection propagation.
- Polymorphism in gidB gene as a genetic marker for the mycobacterium tuberculosis Q1 cluster and implications for the streptomycin resistance levelPublication . Perdigão, João; Macedo, Rita; Machado, Diana; Silva, Carla; Jordão, Luísa; Couto, Isabel; Viveiros, Miguel; Portugal, IsabelDevelopment of streptomycin-resistance in Mycobacterium tuberculosis is usually associated with mutations in rpsL and rrs genes, although up to 50% of clinical streptomycin-resistant isolates may present no mutation in either of these genes. The situation in Lisbon Health Region is similar, although mutations in rrs gene are only rarely detected. In the present report we investigate the role of gidB gene mutations in streptomycin resistance. We have analyzed 52 streptomycin-resistant and 30 streptomycin-susceptible Mycobacterium tuberculosis clinical isolates by sequencing and endonuclease analysis of the gidB and rpsL genes. All clinical isolates were genotyped by 12-loci MIRU-VNTR. Semiquantitative drug susceptibility testing was also performed to a select set of isolates to assess the resistance levels towards streptomycin. The gidB gene of 18 streptomycin-resistant isolates was sequenced and four missense mutations were found: F12L (1/18), L16R (18/18), A80P (4/18) and S100F (18/18). The remaining isolates were screened by endonuclease analysis for mutations A80P in gidB and K43R in rpsL gene. Overall, mutation A80P in gidB gene was found in 7 streptomycin-resistant isolates and 12 streptomycin-susceptible multidrug resistant isolates. Also noteworthy, comparison of the distribution of gidB, rpsL and rrs mutations revealed that gidB A80P mutation was only present in isolates without rpsL and rrs mutations. Moreover, this specific mutation was found among all isolates belonging to genetic cluster Q1. Streptomycin quantitative drug susceptibility testing showed that isolates carrying the GidB A80P mutation were streptomycin intermediate-level resistant and that standard drug susceptibility testing yielded inconsistent results probably due to borderline resistance. Bioinformatic analysis on the degree of conservation showed that the GidB A80P mutation is predicted to affect protein function. We conclude that gidB mutations may explain the high number of streptomycin-resistant strainswith no mutation in rpsL or rrs. These mutations might occasionally confer undetected streptomycin low-level resistance in regular drug susceptibility testing. Also, GidB A80P mutations may serve as surrogate markers for Q1 cluster isolates that are associated with multidrug/extensively drug-resistant tuberculosis.
- Interacções Embalagem-Alimento e Segurança AlimentarPublication . Ana, Sanches Silva