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Resistencia do carrapato Boophilus microplus (Acari: Ixodidae) aos piretroides e organofosforados e o tratamento carrapaticida em pequenas fazendas; Resistance to pyrethroids and organophosphorus acaricides in cattle tick Boophilus microplus (Acari Ixodidae)

Marcia Cristina Mendes
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 15/12/2005 PT
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36.21%
Entre os ectoparasitos dos animais bovinos, o carrapato ? Boophilus microplus (Acari: Ixodidae) - continua sendo uma das principais causas das perdas econômicas na pecuária do Estado de São Paulo. A situação atual do controle do carrapato caracteriza-se por uma crise na produção de novas moléculas de parasiticidas e o desenvolvimento acelerado da resistência dos parasitas aos produtos usados. O presente trabalho teve por objetivo verificar o perfil de sensibilidade do carrapato B. microplus nas fazendas localizadas em alguns municípios do Vale do Ribeira e no município de Pindamonhangaba e propor um sistema de tratamento carrapaticida com base na infestação de paternóginas. Foram realizados testes de larvas - LPT (larval packet test) adotado pela FAO - teste de imersão com a fêmea adulta e o levantamento sobre as práticas de controle adotadas nas duas regiões. Os resultados de resistência para as fazendas de Pindamonhangaba mostraram que, para cipermetrina 15,4% das fazendas foram classificadas como sensível; 7,7% com resistência nível I; 69,2% com resistência nível II e 7,7% com resistência nível III. Para a deltametrina 23% sensível; 38,5% com resistência nível II e 38,5% com resistência nível III. Para o organofosforado clorpirifós 54% mostraram-se sensível; 38...

Study of the traction resistance of mitral valve chordae tendineae

Lobo,Frederico Lafraia; Takeda,Flávio Roberto; Brandão,Carlos Manuel de Almeida; Braile,Domingo Marcolino; Jatene,Fabio Biscegli; Pomerantzeff,Pablo Maria Alberto
Fonte: Faculdade de Medicina / USP Publicador: Faculdade de Medicina / USP
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/10/2006 EN
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OBJECTIVE: To determinate the extension and the resistance of the primary mitral valve chordae tendineae when submitted to traction. The importance of keeping the integrity of papillary muscle, chordae tendineae, and mitral valve cuspid when the replacement of this valve occurs is clear, but the knowledge of the maximum resistance that a primary tendinea chorda can withstand is not known. METHODS: Eight hearts were dissected, and one hundred and thirty two primary human chordae tendineae were measured (length and thickness) and submitted to traction under controlled conditions so that the absolute resistance, resistance relative to thickness (relative resistance), and elongation could be measured. RESULTS: The correlation between the elongation at the moment of rupture and the thickness was equal to 1.54 + 17.02 x thickness (P = 0.026); and to absolute resistance was equal to 0.95 + 1.42 x resistance (P < 0.001); and to the resistance relative to thickness (relative resistance) was equal to 1.95 + 0.08 x relative resistance (P = 0.009). The correlation between the absolute resistance and the thickness was equal to 0.26 + 14.53 x thickness (P < 0.001). CONCLUSION: The resistance of primary mitral valve chordae tendineae is associated with its thickness and elongation at the moment of rupture...

Effect of Abolishment of the Use of Antimicrobial Agents for Growth Promotion on Occurrence of Antimicrobial Resistance in Fecal Enterococci from Food Animals in Denmark

Aarestrup, Frank Møller; Seyfarth, Anne Mette; Emborg, Hanne-Dorthe; Pedersen, Karl; Hendriksen, René S.; Bager, Flemming
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /07/2001 EN
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From 1995 to 2000, a total of 673 Enterococcus faecium and 1,088 Enterococcus faecalis isolates from pigs together with 856 E. faecium isolates from broilers were isolated and tested for susceptibility to four classes of antimicrobial agents used for growth promotion as part of the Danish program of monitoring for antimicrobial resistance. The four antimicrobials were avilamycin, erythromycin, vancomycin, and virginiamycin. Major changes in the use of antimicrobial agents for growth promotion have occurred during the last 6 years in Denmark. The government banned the use of avoparcin in 1995 and of virginiamycin in 1998. Furthermore, the producers have voluntarily stopped all use beginning in 1999. The avoparcin ban in 1995 was followed by a decrease in the occurrence of glycopeptide-resistant E. faecium (GRE) in broilers, from 72.7% in 1995 to 5.8% in 2000. The occurrence of glycopeptide resistance among isolates from pigs remained constant at around 20% from 1995 to 1997. It was shown that, in GRE from pigs, the genes encoding macrolide and glycopeptide resistance were genetically linked and that, following the decrease in the use of tylosin during 1998 and 1999, the occurrence of GRE in pigs decreased to 6.0% in 2000. From 1995 to 1997 the occurrence of erythromycin resistance among E. faecium and E. faecalis isolates from pigs was almost 90%. Use of tylosin decreased considerably during 1998 and 1999...

Low-Level Resistance to Rifampin in Streptococcus pneumoniae

Meier, Patricia Stutzmann; Utz, Silvia; Aebi, Suzanne; Mühlemann, Kathrin
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /03/2003 EN
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Rifampin is recommended for combination therapy of meningitis due to β-lactam-resistant Streptococcus pneumoniae. High-level rifampin resistance (MIC, ≥4 mg/liter) has been mapped to point mutations in clusters I and III of rpoB of the pneumococcus. The molecular basis of low-level resistance (MICs, ≥0.5 and <4 mg/liter) was analyzed. Spontaneous mutants of clinical pneumococcal isolates were selected on Columbia sheep blood agar plates containing rifampin at 0.5, 4, 10, or 50 mg/liter. Low-level resistance could be assigned to mutations in cluster II (I545N, I545L). Sensitive (MIC, <0.048 mg/liter) wild-type strains acquired low-level resistance at a rate approximately 10 times higher than that at which they acquired high-level resistance (average mutation frequencies, 2.4 × 10−7 for low-level resistance versus 2.9 × 10−8 for high-level resistance [P < 0.0001]). In second-step experiments, the frequencies of mutations from low- to high-level resistance were over 10 times higher than the frequencies of mutations from susceptibility to high-level resistance (average mutation frequencies, 7.2 × 10−7 versus 5.0 × 10−8 [P < 0.001]). Mutants with low-level resistance were stable upon passage. Sequencing of a clinical isolate with low-level resistance (MIC...

AcrAB-TolC Directs Efflux-Mediated Multidrug Resistance in Salmonella enterica Serovar Typhimurium DT104

Baucheron, Sylvie; Tyler, Shaun; Boyd, David; Mulvey, Michael R.; Chaslus-Dancla, Elisabeth; Cloeckaert, Axel
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /10/2004 EN
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Multidrug-resistant Salmonella enterica serovar Typhimurium definitive phage type 104 (DT104) strains harbor a genomic island, called Salmonella genomic island 1 (SGI1), which contains an antibiotic resistance gene cluster conferring resistance to ampicillin, chloramphenicol, florfenicol, streptomycin, sulfonamides, and tetracyclines. They may be additionally resistant to quinolones. Among the antibiotic resistance genes there are two, i.e., floR and tet(G), which code for efflux pumps of the major facilitator superfamily with 12 transmembrane segments that confer resistance to chloramphenicol-florfenicol and the tetracyclines, respectively. In the present study we determined, by constructing acrB and tolC mutants, the role of the AcrAB-TolC multidrug efflux system in the multidrug resistance of several DT104 strains displaying additional quinolone resistance or not displaying quinolone resistance. This study shows that the quinolone resistance and the decreased fluoroquinolone susceptibilities of the strains are highly dependent on the AcrAB-TolC efflux system and that single mutations in the quinolone resistance-determining region of gyrA are of little relevance in mediating this resistance. Overproduction of the AcrAB efflux pump...

Why Do F1 Screens Estimate Higher Frequencies of Cry2Ab Resistance in Helicoverpa armigera (Lepidoptera: Noctuidae) Than Do F2 Screens?

Mahon, R. J.; Downes, S.; James, W.; Parker, T.
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica Formato: text/html
EN
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F2 and F1 tests to detect resistance to Cry2Ab in Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) were performed during the 2007–2008 summer. F2 tests indicated a resistance frequency of 0.006, which is similar to the published resistance frequencies for this species during the summers spanning 2002–2006. In contrast F1 tests indicated a resistance frequency of 0.033. Thus, F1 tests isolated Cry2Ab resistance alleles almost six-fold more frequently than the F2 method. A discrepancy might be expected if the F2 tests detected resistance conferred by more than one locus because F1 tests identify only the form of resistance present in the tester resistant colony. However, if so, F2 tests would detect more, not fewer, cases of resistance. In addition, complementation tests on 10 separate isolates indicate that there is only one common form of resistance. We hypothesized that some “resistance alleles” are homozygous lethal if autozygous (as generated in F2 tests) but not as allozygous homozygotes (as generated in F1 tests). The hypothesis was extended to accommodate the possibility that alleles at linked loci may be homozygous lethal. Neither of two tests of the hypothesis provided evidence that any alleles that confer resistance are associated with severe fitness costs. Thus we are presently unable to explain the basis of the difference in frequencies between the methods. Because of the simplicity of the F1 tests...

Identification des réseaux transcriptionnnels de résistance aux antifongiques chez Candida albicans

Znaidi, Sadri
Fonte: Université de Montréal Publicador: Université de Montréal
Tipo: Thèse ou Mémoire numérique / Electronic Thesis or Dissertation
FR
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Plusieurs souches cliniques de Candida albicans résistantes aux médicaments antifongiques azolés surexpriment des gènes encodant des effecteurs de la résistance appartenant à deux classes fonctionnelles : i) des transporteurs expulsant les azoles, CDR1, CDR2 et MDR1 et ii) la cible des azoles 14-lanostérol déméthylase encodée par ERG11. La surexpression de ces gènes est due à la sélection de mutations activatrices dans des facteurs de transcription à doigts de zinc de la famille zinc cluster (Zn2Cys6) qui contrôlent leur expression : Tac1p (Transcriptional activator of CDR genes 1) contrôlant l’expression de CDR1 et CDR2, Mrr1p (Multidrug resistance regulator 1), régulant celle de MDR1 et Upc2p (Uptake control 2), contrôlant celle d’ERG11. Un autre effecteur de la résistance clinique aux azoles est PDR16, encodant une transférase de phospholipides, dont la surexpression accompagne souvent celle de CDR1 et CDR2, suggérant que les trois gènes appartiennent au même régulon, potentiellement celui de Tac1p. De plus, la régulation transcriptionnelle du gène MDR1 ne dépend pas seulement de Mrr1p, mais aussi du facteur de transcription de la famille basic-leucine zipper Cap1p (Candida activator protein 1)...

Le changement organisationnel : la prédiction des comportements de soutien et de résistance par le biais des préoccupations

Meunier, Sophie
Fonte: Université de Montréal Publicador: Université de Montréal
Tipo: Thèse ou Mémoire numérique / Electronic Thesis or Dissertation
FR
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36.25%
Depuis plus de 50 ans, les chercheurs s’intéressent à la résistance au changement. Or, malgré plusieurs années de recherche, on ne sait toujours pas exactement quelles variables peuvent prédire les comportements de résistance et encore moins ceux de soutien. La présente thèse vise à pallier cette lacune en identifiant des variables pouvant expliquer à la fois les comportements de soutien et de résistance lors d’un changement organisationnel majeur. Le modèle des phases de préoccupations (Bareil 2004a) s’avère intéressant à cet effet puisqu’il intègre bien les savoirs actuels et s’adapte à différents changements. L’objectif principal de cette thèse est donc de vérifier jusqu’à quel point les comportements de soutien et de résistance peuvent être prédits par les phases de préoccupations, en tenant compte de l’engagement affectif envers le changement comme variable médiatrice et du rôle des acteurs et de l’avancement de la mise en œuvre comme variables modératrices. Pour ce faire, une étude a été menée auprès d’enseignants, de professionnels et de directeurs d’une Commission scolaire québécoise ayant implanté une réforme majeure provoquant des préoccupations d’intensité variée et des comportements divers...

Étude de la résistance des sous-types non-B du VIH-1 aux antirétroviraux au Mali

Haidara, Alpha
Fonte: Université de Montréal Publicador: Université de Montréal
Tipo: Thèse ou Mémoire numérique / Electronic Thesis or Dissertation
FR
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36.23%
Nous avons effectué ce travail afin d’évaluer l’impact d’une utilisation accrue des antirétroviraux (ARV) sur l’émergence de la résistance dans le cadre d’une cohorte de sujets infectés par le VIH-1, enrôlés au Mali pour recevoir la thérapie antirétrovirale. La première partie de ce travail a évalué la résistance primaire auprès de 101 sujets naïfs aux ARV. Cette étude a démontré que la majorité des sujets (71,3%) étaient infectés par le sous-type CRF02_AG. La prévalence de la résistance primaire était de 9,9%. Ce chiffre dépasse largement la moyenne de 5,5% observée dans les pays en développement et le seuil des 5% fixé par l’OMS dans le cadre de la surveillance de la résistance. Les mutations associées aux analogues de la thymidine ou « Thymidine-associated Mutations » (TAMs): M41L, D67N, L210W, T215A/Y, K219E liées à la résistance aux inhibiteurs nucléosidiques de la transcriptase inverse (INTI) ainsi que les mutations K103N, V108I, V179E et Y181C impliquées dans la résistance aux inhibiteurs non nucléosidiques de la transcriptase inverse (INNTI) étaient majoritairement observées. Ces mutations sont compatibles avec les régimes de traitement de première ligne utilisés au Mali...

Temperate bacteriophages and the molecular epidemiology of antibiotic resistance in Salmonella enterica.

Tan, Sophia
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2010
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Foodborne diseases caused by non-typhoidal Salmonella represent an important public health problem worldwide (Zhao et al., 2003). The transmission of Salmonella between animals and humans has been well established in epidemiological studies. In the case of complicated illness caused by Salmonella where antibiotics need to be administered, treatment can be compromised if the infecting organism is resistant to the prescribed antimicrobial agent. This study and earlier studies have shown that many Salmonella carry temperate bacteriophages as lysogens. Many of these bacteriophages are capable of mediating generalised transduction (Schicklmaier and Schmieger, 1995; Schicklmaier et al., 1998; Mmolawa et al., 2002). Schmieger and Schicklmaier (1999) demonstrated that bacteriophages ES18 and PDT17 are capable of transduction of antibiotic resistance genes from DT104. Phage-mediated transduction of antibiotic resistance genes has been largely neglected in the study of genetic transfer of antibiotic resistance in bacteria. This study investigates whether bacteriophages exist in antibiotic resistant Salmonella isolates. Such temperate phages in antibiotic resistant isolates could play a significant role in the transfer of resistance to other species of enteric bacteria...

Identification of sources of disease resistance in Chinese faba bean germplasm for incorporation in Australian cultivars.

Jamali, Ali Raza
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2009
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A total of 115 Chinese accessions from six provinces with diverse climate, topography and farming systems were screened for reaction to three fungal diseases Ascochyta blight, (Acochyta fabae), chocolate spot (Botrytis fabae) and Cercospora leaf spot (Cercospora zonata). Not all the accessions were included in three disease screening trials due to a limited number of seeds for some accessions. However, a majority of lines were included in all three disease screening trials and the remaining at least for two trials. In the Ascochyta blight screening trial 96 Chinese accessions were evaluated and while the majority of lines were susceptible a number of lines including 1688, 1689 (Gansu), 1729 (Guangxi), 1750 (Jiangsu), 1998 and 1999 (Qinghai) were identified with a significant degree of heterogeneity including a low proportion of resistant plants. Single plants with a disease score of either 1 (resistant) or 3 (moderately resistant) could be used for the development and selection of resistant lines. The effect of three concentrations of B. fabae inoculum was observed on four cultivars 1714-1, Nura, Fiesta and Icarus. The disease development was proportional to the amount of inoculum irrespective of cultivars but the relative responses of cultivars varied between treatments...

Genetic and biological characterisation of resistance to root lesion nematode Pratylenchus thornei in wheat.

Linsell, Katherine Joanne
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2013
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Root lesion nematodes of the genus Pratylenchus feed and reproduce in the root cortex of many plant species, including wheat. Migration through root tissue causes extensive root damage, and in turn severe reductions in growth and yield. In Australia, one of the most prevalent and widespread species affecting wheat is Pratylenchus thornei. Due to the wide host range of Pratylenchus spp. and the restrictions and inefficiency of chemical pesticides, the development of resistant cultivars has become increasingly important. Despite the identification and investigation of several resistance sources and resistance quantitative trait loci (QTL), no P. thornei resistance has been integrated into commercial cultivars. In addition, prior to this study, the biological resistance mechanisms of wheat against P. thornei were not well characterised. The identification of novel sources of genetic resistance in wheat and understanding of the biological mechanisms will allow effective combinations of genes either to be used alternatively or pyramided to generate effective and stable Pratylenchus resistance. The major objectives of the study were to identify genetic loci associated with P. thornei resistance and to investigate the associated biological mechanisms in a double haploid wheat population developed from a cross between the synthetically derived Sokoll and the Australian adapted Krichauff parental lines. The resistance to P. thornei observed in the Sokoll x Krichauff wheat population is complex and under the control of several loci which suppress all nematode developmental stages. The four main components of the root invasion process by Pratylenchus: root attraction...

Virulence factors associated with antimicrobial resistance determinants among Escherichia coli and Klebsiella spp

Calhau, Vera Mónica Tavares Vinhas
Fonte: Universidade de Coimbra Publicador: Universidade de Coimbra
Tipo: Tese de Doutorado
ENG
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Escherichia coli and Klebsiella spp. are important pathogens, responsible for several infectious diseases. These members of Enterobacteriaceae family are of particularly concerning due to a high increase in their resistance to antimicrobials. The detection of more resistant strains brings into question if this enhancement of resistance may be accompanied by an increase in virulence. If so, extremely pathogenic strains would start to emerge, and no antibiotic therapy would be available to fight them, leading to serious public health problems. Thus, the main objective of this research was to understand the relation between virulence and resistance among E. coli collected from different origins and Klebsiella spp.. The interplay between resistance and virulence was studied among Uropathogenic E. coli (UPEC). E. coli strains are classified into four main phylogenetic groups. More virulent strains belong mainly to phylogroup B2 and, to a lesser extent, to group D, and most of the commensal strains belong to groups A and B1. During the characterization of strains, a new genotype was discovered in the Clermont method, which is used to assess phylogenetic groups. This yjaA/ tspE4.C2 genotype was assigned to phylogroup B2. Pathogenicity islands (PAIs) are mobile genetic elements that carry virulence genes and may increase the virulence of bacteria. PAI I536...

Genotypic resistance profiles to antiretroviral drugs in HIV-1 circulating among injecting drug users in the great Lisbon

Videira e Castro, Sandra; Sousa, Carina; Pádua, Elizabeth; Esteves, Aida; Parreira, Ricardo; Piedade, João
Fonte: IHMT Publicador: IHMT
Tipo: Conferência ou Objeto de Conferência
Publicado em 20/04/2013 ENG
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Genotypic resistance profiles to antiretroviral drugs in HIV-1 circulating among injecting drug users in the Greater Lisbon Sandra Videira e Castro1; Carina Sousa1; Elizabeth Pádua3; Aida Esteves1,2; Ricardo Parreira1,2; João Piedade1,2 1Grupo de Virologia, UEI de Microbiologia Médica; 2Unidade de Parasitologia e Microbiologia Médicas (UPMM) Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa Rua da Junqueira nº100, 1349-008 Lisboa, Portugal 3Laboratório de Referência da Sida, Instituto Nacional de Saúde Dr. Ricardo Jorge Avenida Padre Cruz, 1649-016 Lisboa, Portugal Background and Objectives The introduction of highly active antiretroviral therapy has significantly improved the ability to maintain human immunodeficiency virus type 1 (HIV-1) replication to very low levels for an extended period of time, providing a better quality of life to infected patients. The acquisition and transmission of HIV-1 drug resistance mutations is a major public health concern, so the search for better antiretroviral (ARV) therapeutic agents is a constant challenge. In recent years, in an effort to target other functions at the virus replication cycle beyond those carried out by the viral enzymes protease (PR), reverse transcriptase (RT) and integrase (IN)...

Antimicrobial resistance surveillance in Europe 2013: Annual Report of the European Antimicrobial Resistance Surveillance Network (EARS-Net)

European Antimicrobial Resistance Surveillance Network (EARS-Net)
Fonte: European Centre for Disease Prevention and Control (ECDC) Publicador: European Centre for Disease Prevention and Control (ECDC)
Tipo: Relatório
Publicado em //2014 ENG
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Portugal - EARS-Net Management Team & National representatives of EARS-Net (Manuela Caniça, José Artur Paiva, Vera Manageiro, Eugénia Ferreira); The results presented in this report are based on antimicrobial resistance data from invasive isolates reported to EARS-Net by 30 EU/EEA countries in 2014 (data referring to 2013), and on trend analyses of EARS-Net data reported by the participating countries during the period 2010 to 2013. The antimicrobial resistance situation in Europe displays large variations depending on bacteria, antimicrobial group and geographical region. For several antimicrobial group and bacterium combinations, a north-to-south and west-to-east gradient is evident in Europe. In general, lower resistance percentages are reported by countries in the north and higher percentages reported by countries in the south and east of Europe. Overall, the most concerning trends in Europe in 2013 were related to the occurrence of resistance in gram-negative bacteria (Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Acinetobacter species). For E. coli and K. pneumoniae, a continuous increase in resistance to key antimicrobial groups was noted. A majority of the isolates reported to EARS-Net in 2013 was resistant to at least one of the antimicrobial groups under surveillance...

Nilotinib efflux and resistance development: the effects of combination and concomitant therapies on the transport and efficacy of Nilotinib.

Eadie, Laura Nicole
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2013
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36.22%
Chronic myeloid leukaemia (CML) is characterised by the presence of Bcr-Abl tyrosine kinase. Tyrosine kinase inhibitors (TKIs), such as imatinib, and more recently nilotinib and dasatinib, act by specifically binding to the Bcr-Abl kinase domain. The advent of TKIs resulted in significantly improved treatment outcomes for the majority of patients with CML. However, the focus is now customised treatment regimes employing drug combinations to reduce resistance development and maximise treatment outcomes. The present study investigated the interaction of nilotinib with efflux transporters and 1) assessed how concomitant administration of additional drugs may enhance the effects of nilotinib in patients and 2) how altered expression or inhibition of these transporters affected nilotinib transport and function. Secondly, in vitro cell line models of nilotinib resistance were generated in order to replicate modes of nilotinib resistance in vivo. The reported relationship between nilotinib and efflux transporters ABCB1 and ABCG2 is conflicting and nilotinib has previously been reported to inhibit the function of OCT-1. Thus, in order to resolve conjecture, a novel approach was employed to determine the effect of ABCB1/ABCG2 inhibition on nilotinib-mediated Bcr-Abl kinase inhibition. Results demonstrated ABCB1-mediated nilotinib transport was concentration dependent: transport of nilotinib occurred at low concentrations whereas inhibition of both ABCB1 and ABCG2 occurred at high nilotinib concentrations. Additionally...

Étude de la résistance aux antibiotiques des entérocoques d'origine animale du Québec

Tremblay, Cindy-Love
Fonte: Université de Montréal Publicador: Université de Montréal
Tipo: Thèse ou Mémoire numérique / Electronic Thesis or Dissertation
FR
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36.24%
Les entérocoques font partie de la flore normale intestinale des animaux et des humains. Plusieurs études ont démontré que les entérocoques d’origine animale pouvaient représenter un réservoir de gènes de résistance aux antibiotiques pour la communauté humaine et animale. Les espèces Enterococcus faecalis et Enterococcus faecium sont importantes en santé publique; elles sont responsables d’environ 12% de toutes les infections nosocomiales aux États-Unis. Au Canada, les cas de colonisation et/ou d’infections à entérocoques résistants à la vancomycine ont plus que triplé de 2005 à 2009. Un total de 387 isolats E. faecalis et E. faecium aviaires, et 124 isolats E. faecalis porcins ont été identifiés et analysés pour leur susceptibilité aux antibiotiques. De hauts pourcentages de résistance envers les macrolides et les tétracyclines ont été observés tant chez les isolats aviaires que porcins. Deux profils phénotypiques prédominants ont été déterminés et analysés par PCR et séquençage pour la présence de gènes de résistance aux antibiotiques. Différentes combinaisons de gènes de résistance ont été identifiées dont erm(B) et tet(M) étant les plus prévalents. Des extractions plasmidiques et des analyses par hybridation ont permis de déterminer...

The Role of Second Generation Antiretroviral Drugs in HIV-1 Subtype B and non-B Variants Harboring Natural Polymorphisms and Drug Resistance Mutations.

Asahchop, Eugene L.
Fonte: Université de Montréal Publicador: Université de Montréal
Tipo: Thèse ou Mémoire numérique / Electronic Thesis or Dissertation
EN
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Cette thèse traite de la résistance du VIH-1 aux antirétroviraux, en particulier de l'activité antivirale de plusieurs inhibiteurs non nucléosidiques de la transcriptase inverse (INNTI) ainsi que des inhibiteurs de protéase (IP). Nous avons exploré l’émergence et la spécificité des voies de mutations qui confèrent la résistance contre plusieurs nouveaux INNTI (étravirine (ETR) et rilpivirine (RPV)) (chapitres 2 et 3). En outre, le profil de résistance et le potentiel antirétroviral d'un nouvel IP, PL-100, est présenté dans les chapitres 4 et 5. Pour le premier projet, nous avons utilisé des sous-types B et non-B du VIH-1 pour sélectionner des virus résistants à ETR, et ainsi montré que ETR favorise l’émergence des mutations V90I, K101Q, E138K, V179D/E/F, Y181C, V189I, G190E, H221H/Y et M230L, et ce, en 18 semaines. Fait intéressant, E138K a été la première mutation à émerger dans la plupart des cas. Les clones viraux contenant E138K ont montré un faible niveau de résistance phénotypique à ETR (3,8 fois) et une diminution modeste de la capacité de réplication (2 fois) par rapport au virus de type sauvage. Nous avons également examiné les profils de résistance à ETR et RPV dans les virus contenant des mutations de résistance aux INNTI au début de la sélection. Dans le cas du virus de type sauvage et du virus contenant la mutation unique K103N...

Characterization of antimicrobial resistance in Aeromonas and Vibrio isolated in Canada from fish and seafood

Uhland, F.Carl
Fonte: Université de Montréal Publicador: Université de Montréal
Tipo: Thèse ou Mémoire numérique / Electronic Thesis or Dissertation
EN
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Plusieurs études ont examiné la sensibilité aux antimicrobiens chez les bactéries d’organismes provenant de produits issus de l’aquaculture ou de leur environnement. Aucune information n’est cependant disponible concernant la résistance aux antimicrobiens dans les bactéries de la flore de poissons ou de fruits de mer vendus au détail au Canada. C’est particulièrement vrai en ce qui a trait aux bactéries des genres Aeromonas et Vibrio, dont certaines espèces sont des agents pathogènes zoonotiques connus. Au cours de cette étude, la sensibilité aux antimicrobiens d’isolats d’Aeromonas spp. et de Vibrio spp. provenant de poissons et de crevettes domestiques et importés a été mesurée à l’aide de techniques de micro dilution en bouillon et/ou de diffusion sur disque. Les classes d’antimicrobiens examinés comprenaient les tétracyclines (TET), les inhibiteurs de la voie des folates (sulfadiméthoxine-triméthoprime, SXT), le florfenicol (FLO), et les quinolones (acide nalidixique / enrofloxacine, NA/ENO). Des valeurs seuils épidémiologiques pour Aeromonas et Vibrio ont été établies en utilisant la méthode d’interprétation normalisée des données de résistance provenant de diffusion sur disque. La recherche de gènes de résistance associés au profil de résistance des isolats a été effectuée en utilisant des PCRs et des puces ADN. Le nombre d’isolats résistants aux divers antimicrobiens parmi les 201 isolats d’Aeromonas et les 185 isolats de Vibrio étaient respectivement les suivants: TET (n=24 et 10)...

Análises da resistência genética à tospovirus e potyvirus em acessos de Solanum (secção lycopersicon); Genetic analysis of resistance to tospovirus and potyvirus in access of Solanum (section lycopersicon)

Oliveira, Renata Maria de
Fonte: Universidade Federal de Goiás; Brasil; UFG; Programa de Pós-graduação em Agronomia (EAEA); Escola de Agronomia e Engenharia de Alimentos - EAEA (RG) Publicador: Universidade Federal de Goiás; Brasil; UFG; Programa de Pós-graduação em Agronomia (EAEA); Escola de Agronomia e Engenharia de Alimentos - EAEA (RG)
Tipo: Dissertação Formato: application/pdf
POR
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Tomato is one of the most cultivated vegetables worldwide, and this is an important factor in their vulnerability to attack by pests and diseases, which contribute to the decrease in production and affects the quality of the fruit. Among diseases affecting tomato production, the ones caused by viruses are of the utmost importance, which are more difficult to control, highlighting those caused by species of the genus Tospovirus, which can cause losses of up to 100 %. The tospoviruses are responsible for the disease known as 'tomato spotted wilt' and are transmitted by thrips. In Brazil, four species of tospoviruses occur in tomato: Tomato spotted wilt virus (TSWV), Tomato chlorotic spot virus (TCSV), Groundnut ringspot virus (GRSV) and Chrysanthemum stem necrosis virus (CSNV), with a greater incidence of GRSV. The first TSWV resistance gene identified was the Sw-5, which is effective against all species of tospoviruses infecting tomato and is widely used in breeding programs for this reason, because the resistance gene presents a dominant trait. Sources of resistance were found in other wild accessions of the species S. chilense, S. habrochaites, S. pimpinellifolium, S. corneliomuelleri and S. lycopersicum, showing promising results as sources of resistance for use in breeding programs. To identify a source of tospovirus resistance in wild accessions of the Germplasm Bank of Embrapa Hortaliças...