Diss. (sammanfattning) Stockholm : Karol. inst. / Härtill 5 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst. / Härtill 6 uppsatser.

The objectives of this study were to investigate nutrient retention, intI1 prevalence, and compost maturity rates for poultry litter co-composted with 5, 10, and 20% southern yellow pine biochar and with or without 2% wood vinegar (WV). Samples were collected at 0, 57, and 112 days to measure nitrogen, phosphorus, and potassium (N, P, K) concentrations, microbial counts, pH, moisture content, carbon to nitrogen (C:N) ratio, and intI1 abundance. Composts were aerated once a week and the temperature was also recorded once a week. There was sufficient rainfall so no additional water was added. The results showed that N and P concentrations significantly increased over time in all treatments except 20% biochar and 20% biochar + wood vinegar, while K concentrations significantly decreased. In general, composting with wood vinegar significantly decreased nutrient concentrations; however, all nutrient concentrations were much higher than typical animal manure fertilizers. Increases in biochar level resulted in significantly lower bacteria counts and significantly higher fungi counts. Compost treatments containing wood vinegar had significantly lower bacteria and fungi counts, indicating that southern yellow pine wood vinegar had a biocide effect on microorganisms, and may be not suitable for composting at that application rate. intI1 prevalence was not significantly different among treatments, which may be due to insufficient thermophilic composting. Because thermophilic temperatures were not achieved, the compost was not mature by the end of the study; therefore, compost maturity rates could not be determined.

No description available.

A consequence of antimicrobial use in food production systems is the potential for antimicrobial resistant (AMR) bacteria to develop and transfer to the human population via the food chain. Integrons have been identified as critical factors in the development of AMR. Despite Australia being amongst the world’s largest exporters of beef, there is a general lack of data on the prevalence of AMR in bacteria from Australian beef cattle. Consequently, the aim of this study has been to contribute to research strategies and knowledge of AMR by investigating integron-associated antimicrobial resistance in Australian beef cattle production systems. This study developed a protocol that targets resistance integrons. The protocol was trialled on 50 bovine faecal samples with a total of 39 integron-containing isolates recovered. Characterisation of the integrons was performed and it was determined that the majority of integrons harboured genes encoding resistance to trimethoprim (dfr) and streptomycin / spectinomycin (aad). The protocol provides an opportunity to rapidly interrogate populations of bacteria within a defined sample for resistance integrons. The protocol was used to investigate integron-associated AMR in Australian beef cattle production systems. Each production system was investigated for resistance integrons to determine if production practices were impacting on the prevalence and types of AMR present. The investigation found that the prevalence of integron-containing bacteria was higher in lot-fed cattle than grass-fed cattle which in turn were higher than organically produced cattle. However, the types of AMR differed very little across production systems and suggested that the higher prevalence of integrons in lot-fed samples may be a function of the intensive nature of this type of production system rather than a result of selective pressure caused by antibiotic use. Although there appeared to be no obvious trends in the types of gene cassettes carried by integrons from differing production systems, if lot-fed cattle continually arrive at slaughter with a higher prevalence of integron-containing bacteria then these cattle may be more likely to contribute to contamination of the final product. Samples from lot-fed, grass-fed and organically produced cattle at slaughter were collected. Despite the apparent unrelatedness of the cattle herds, there was little difference in the PCR prevalence of class 1 and class 2 integrase, the gene cassettes harboured by the integrons, and the host organism for the integron. Genes encoding resistance to streptomycin and chloramphenicol (catB8) dominated the majority of arrays regardless of production system, although two novel arrays were identified. One of the arrays, cmlA5-blaoxa-10-aadA1, was found in A. veronii biovar Sobria isolates from organic cattle thereby confirming the ability of multi-resistant integrons to persist in environments that have no obvious antimicrobial selection. The abattoir study revealed an unusually high prevalence of Aeromonas isolates carrying integrons. It appeared to implicate the abattoir environment as a direct contributor to the presence of integron-containing bacteria in each herd. Characterisation of each Aeromonas isolate determined that the isolates were not clonal in nature and not a result of persistent contamination at the abattoir. It seemed more probable that the Aeromonas isolates were present in the cattle prior to arrival and may have been acquired from the environment. To explore this further, soil samples from cattle associated and non-cattle associated areas were tested for the presence of resistance integrons. The prevalence of class 1 integrons was higher in cattle-associated soil samples than in non-cattle-associated soil samples, however the diversity of gene cassettes harboured by the integrons was greater in non-cattle-associated samples than cattle-associated samples. An array harbouring blaoxa-30 was isolated from a non-cattle-associated soil sample. Its presence continues to highlight the potential for multi-resistant integrons to exist in environments with no obvious antimicrobial selection pressure.The detection of seldom reported class 1 integron arrays in this study indicates the potential of the developed protocol to interrogate populations of bacteria for resistance integrons. This is highlighted further by the isolation of a novel class 2 integron. This novel class 2 integron from Providencia stuartii possesses a class 2 integrase that is predicted to be fully functional and has a variable region comprising nine ORFs that do not encode AMR genes. Overall, this study demonstrated that integrons are present in all cattle production systems employed in Australia and although the prevalence of integrons appeared to align with the anticipated use of antimicrobials in each system, differences in the integrons from each production system were not evident. As the similarities observed between integrons extend to isolates from organically produced cattle and from non-cattle associated soil samples it is suggested that the majority of integrons identified in this study are not present as a direct result of antimicrobial use in cattle production. Nevertheless, the potential of integrons to capture AMR genes remains and their presence in beef cattle highlights the need for the continued prudent use of antimicrobials.

Submitted by Liliane Ferreira (ljuvencia30@gmail.com) on 2018-10-02T12:04:15Z No. of bitstreams: 2 Tese - Aline Pedrosa de Oliveira - 2016.pdf: 3128576 bytes, checksum: bbad449f3830d7359e905a2812b2a74e (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2018-10-03T11:45:04Z (GMT) No. of bitstreams: 2 Tese - Aline Pedrosa de Oliveira - 2016.pdf: 3128576 bytes, checksum: bbad449f3830d7359e905a2812b2a74e (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2018-10-03T11:45:04Z (GMT). No. of bitstreams: 2 Tese - Aline Pedrosa de Oliveira - 2016.pdf: 3128576 bytes, checksum: bbad449f3830d7359e905a2812b2a74e (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2016-12-22 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / Salmonella enterica is a foodborne pathogen with multifactorial and complex pathogenic mechanisms. Identification of the presence of virulence genes and antimicrobial resistance profiles in isolates of poultry origin provides relevant information on the risk attributed to the consumption of products contaminated by the agent. The objective of this study was to verify the susceptibility profile of Salmonella enterica for nalidixic acid (30μg), amicacin (30μg), ampicillin (10mg), ceftiofur (30μg), chloramphenicol (30μg), ciprofloxacin (5μg), enrofloxacin (5μg), streptomycin (10mg), gentamicin (10mg), tetracycline (30μg), tobramycin (10mg) and trimethoprim (5μg) used in both human and animal medicine, to investigate the presence of multiresistant isolates, to detect the presence of the variable region of the class 1 Integron, to analyze the association between the presence of Class 1 Integron and antimicrobial resistance and to evaluate the presence of virulence genes located in the islands of virulence 1 (invA) and 2 (sseD), gene encoding long polar fimbriae (lpfA) and plasmidial spvR, to identify the virulence profiles and pathogenicity potential of Salmonella enterica serovars isolated from carcasses, hearts, livers, gizzards and environment of slaughterhouses located in the State of Goiás and on chicken carcasses marketed in commercial establishments in Goiânia -GO. The highest resistance frequency was observed for ceftiofur, 19.12% (13/68), followed by streptomycin, gentamicin, tobramycin, tetracycline and trimetropic, 16.18% (11/68) both, nalidixic acid 14.71% (10/68), ampicillin 13.24% (9/68), and enrofloxacin 2,94% (2/68). No resistance was observed for ciprofloxacin, only intermediate, 45.59% (31/68), 100% (68/68) of the isolates were sensitive to amikacin and chloramphenicol. Of the 68 isolates 22 (32.35%) were resistant to one or more antimicrobial principles. Twelve profiles of antimicrobial resistance were identified, 54.54% (12/22) of the isolates presented multiresistance. The variable region of Class 1 Integron was detected in 63.23% (43/68) of the isolates. The presence of this region was not associated with antimicrobial resistance. All slaughterhouses and in most commercial establishments it was possible to identify Salmonella enterica carrying the Integron of class 1 demonstrating the ubiquity of the same. The invA gene was identified in 100% (59/59), sseD in 92.53% (54/59), lpfA in 86.51% (52/54) and spvR in 86.18% (49/59) of the serovars of Salmonella enterica. Six virulence profiles were identified, 77.97% of the isolates were grouped in profile A characterized by the presence of the four virulence genes simultaneously. The knowledge of the virulence profiles of the isolates allows to affirm that the serovars identified in the state of Goiás are potentially virulent and capable of triggering disease in poultry production systems and in humans. / Salmonella enterica é um patógeno de veiculação alimentar com mecanismos de patogenicidade multifatoriais e complexos. A identificação da presença de genes de virulência e de perfis de resistência a antimicrobianos em isolados de origem avícola fornece informações relevantes quanto ao risco atribuído ao consumo de produtos contaminados pelo agente. Pelo exposto, objetivou-se com este trabalho verificar o perfil de suscetibilidade de Salmonella enterica para ácido nalidíxico (30μg), amicacina (30μg), ampicilina (10mg), ceftiofur (30μg), cloranfenicol (30μg), ciprofloxacina (5μg), enrofloxacina (5μg), estreptomicina (10mg), gentamicina (10mg), tetraciclina (30μg), tobramicina (10mg) e trimetoprima (5μg), utilizados tanto na medicina humana quanto animal. Investigar a presença de isolados multirresistentes. Detectar a presença do Integron de classe e analisar a associação entre a presença deste e a resistência antimicrobiana. Ainda avaliar a presença de genes de virulência localizados nas ilhas de virulência 1 (invA) e 2 (sseD), gene codificador de fímbria polar longa (lpfA) e o plasmidial spvR em sorovares de Salmonella enterica isolados a partir de carcaças, corações, fígados, moelas e ambiente de abate de abatedouros localizados no estado de Goiás e em carcaças de frango comercializadas em estabelecimentos comerciais de Goiânia -GO. A maior frequência de resistência foi obervada para ceftiofur, 19,12% (13/68), seguido pelos antimicrobianos, estreptomicina, gentamicina, tobramicina, tetraciclina e trimetropima, 16,18% (11/68), ácido nalidíxico 14,71% (10/68), amplicilina 13,24% (9/68), e enrofloxacina 2,94% (2/68). Não foi observado resistência dos isolados para ciprofloxacina, sendo, 45,59% (31/68), considerados apenas intermediários. Entretanto, 100% (68/68) dos isolados foram sensíveis à amicacina e ao cloranfenicol. Dos 68 isolados, 22 (32,35%) foram resistentes a um ou mais princípios antimicrobianos. Foram identificados 12 perfis de resistência à antimicrobianos e 54,54% (12/22) dos isolados apresentaram multirresistência. A região variável do Integron de Classe 1 foi detectado em 63,23% (43/68) dos isolados. A presença desta região não apresentou associação com a resistência aos antimicrobianos. Em todos os abatedouros e na maioria dos estabelecimentos comerciais foi possível identificar Salmonella enterica transportando o Integron de classe 1, demonstrando a ubiquidade do mesmo. O gene invA foi identificado em 100% (59/59), sseD em 92,53% (54/59), lpfA em 86,51% (52/54) e spvR em 86,18% (49/59) dos sorovares de Salmonella enterica. Foram identificados seis perfis de virulência (A, B, C, D, E e F). Ao todo, 77,97 % dos isolados se agruparam no perfil A, caracterizado pela presença dos quatro genes de virulência simultaneamente. O conhecimento dos perfis de virulência dos isolados permite afirmar que os sorovares identificados no estado de Goiás são potencialmente virulentos e capazes de desencadear doença em sistemas de produção avícola e em humanos.

Nuclear Reactor Pressure Vessels (RPV) are manufactured from medium strength low alloy ferritic steel, specifically selected for its high toughness and good weldability. The ability of the RPV material to resist crack growth is crucial given that it is one of the fundamental containment safety systems of nuclear power plants. For most of their lifetime, the RPV operates at sufficiently elevated temperatures to ensure the material is ductile. However, the development of ductile damage, in the form of voids, and the ability to predict ductile tearing in RPV materials using a mechanistically-based model remains difficult. The Gurson-Tvergaard-Needleman (GTN) model of ductile tearing provides one such tool for predicting ductile damage development in RPV materials. The difficulty in using the GTN model lies in the ability to calibrate the model parameters in a robust manner. The parameters are typically calibrated data, derived from fracture tests and relying on an iterative “trial and error” procedure of numerical simulations and comparison with test data until the model reproduces the experimental behaviour with sufficient accuracy. This research has addressed the development of a mechanistically-based approach to the calibration of the GTN model by developing a new understanding of the ductile fracture mechanism in RPV material through conventional metallography and 3D X-ray computed tomography to image the initiation, growth and coalescence of ductile voids. The metallographic and tomographic data were analysed in a quantitative manner to establish a direct link between the microstructural features and void evolution and the key parameters of the GTN model. This approach has established a more robust mechanistically based method for the calibration of the GTN model that will enhance the conventional iterative calibration procedure. The calibrated model was applied to predict ductile tearing behaviour in compact-tension and notched-tensile specimens. The results showed good agreement with test data and also reproduced the morphology and branching of crack extension observed in practise. Whilst these observations were due, in part, to the numerical solving procedure, they enabled new insights to be gained regarding the development of non-uniform void volume fraction distributions in tested specimensThe results from this research will strengthen the guidance provided to structural integrity engineers in industry regarding the calibration and application of ductile damage mechanics models such as the GTN model for predicting ductile initiation and growth in RPV materials.

No description available.

QepA is a plasmid-mediated efflux pump found in some strains of Escherichia coli, in which it significantly elevates the resistance against quinolones. The protein has similarities with 14-TMS major facilitator superfamily transporters and is situated in the inner membrane of the bacteria. It was acquired by horizontal gene transfer and integrated into a now inactivated class 1 integron, also harbouring several other antibiotic resistance genes such as rmtB and blaTEM-1. QepA alone is not sufficient to raise the resistance level over the clinical breakpoint and is in clinical isolates therefore associated with other quinolone antibiotic resistance genes or quinolone target point mutations. The mechanisms regulating qepA expression are not yet understood. Therefore, in this study the qepA gene was amplified from an E. coli clinical isolate and, together with its upstream promotor sequence, was inserted into the E. coli chromosome. It was shown that qepA gene expression can be induced by exposure to 0.5-fold MIC concentrations of ciprofloxacin, trimethoprim and other DNA damaging antimicrobials. The deletion of a LexA binding site situated after a PcW promotor, which was predicted to drive qepA expression, did not alter this induction behaviour. Nested deletions of up to 200 nts downstream sequence of the PcW promotor, led to the identification of a sequence region required for expression induction. This study showed that qepA expression is induced by environmental factors leading to DNA damage and further identified a previously unknown DNA sequence required for expression regulation.

Orientador: Alexandre Leite Rodrigues de Oliveira / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-08T03:01:25Z (GMT). No. of bitstreams: 1 SabhaJunior_MarioJoseJorge_D.pdf: 14971588 bytes, checksum: 25740c7d964d2a5c4eb70c84cb462b08 (MD5) Previous issue date: 2007 / Resumo: o estabelecimento das redes nervosas que compõem o Sistema Nervoso Central (SNC) é um processo imensamente complexo dependente, não somente da formação de novos pontos de comunicação, as sinapses, mas também da eliminação de sinapses supranumerárias ou incorretas durante o desenvolvimento. Recentemente, foi descrito um mecanismo demonstrando que a ausência da expressão do complexo de histocompatibilidade principal (MHC classe I) no SNC, diminui a remoção de conexões sinápticas extranumerárias durante o desenvolvimento e aumenta a retração sináptica no animal adulto. Interessantemente, a transecção do axônio induz uma extensa retração dos terminais pré-sinápticos da superfície do corpo celular e dendritos dos neurônios axotomizados. No presente trabalho, investigamos as alterações sinaptológicas nos motoneurônios alfa da intumescência lombar em três linhagens de camundongos isogênicos (C57BL/6J, A/J e Balb/cJ), após 1 e 3 semanas da transecção do nervo ciático. Nesse sentido, estudamos a cobertura sináptica dos corpos celulares dos motoneurônios após a lesão. Foram utilizadas medulas espinhais de camundongos machos adultos, as quais foram processadas e analisadas para imunohistoquímica (lH) e microscopia eletrônica de transmissão . (MET). Para IH, foram utilizados anticorpos anti-MHC e anti-sinaptofisina conjugados com anticorpos secundários CY-2 ou CY-3 e analisados em microscópio confocal. Os resultados mostraram aumento significativo da expressão de MHC I na linhagem AIJ, comparativamente à Balb/cJ e C57BL/6J, 1 semana após axotomia. Contudo, mostraram níveis similares de expressão desta molécula 3 semanas após axotomia. Adicionalmente, observamos uma diminuição significativa da expressão de sinaptofisina na linhagem AIJ, após 1 semana da transecção do nervo ciático. Após 3 semanas da lesão nervosa, todas as linhagens, apresentaram níveis similares de expressão de sinaptofisina. Os resultados da MET, após 1 semana da transecção do nervo ciático, mostraram menor cobertura sináptica na linhagem A/J, comparada à Balb/cJ e C57BL/6J. Contudo, 3 semanas após a lesão a linhagem C57BL/6J apresentou menor cobertura sináptica, enquanto AIJ e Balb/cJ recuperam suas aferências. Concluímos que a expressão de MHC I influencia o processo de eliminação sináptica e, possivelmente contribui para o potencial regenerativo dos neurônios axotomizados / Abstract: The wiring of the Central Nervous System (CNS) is an immensely complex process, not only dependent on new communication points, the synapses, but also on the elimination of exuberant or inappropriate synapses during development. Earlier studies have shown that the abscence of class I major histocompatibility complex (class I MHC) in the CNS decreases synaptic elimination during CNS development and increases synaptic retraction in adult. Thus, an axon transection has been shown to induce an extensive detachment of presynaptic terminais from perikarya and dendrites ofaxotomized neurons. In the present work, we investigated synaptological changes in alpha motoneurons from lumbar intumescence in three mice isogenic strains (C57/BL6J, AIJ and Balb/cJ), 1 and 3 weeks after sciatic nerve transection. For this purpose we studied ultrastructurally the synaptic covering of the cell soma of sciatic motoneurons after the lesion. Therefore, spinal cords from adult male mice were processed for transmission electron microscopy (TEM) and imunohistochemistry (IH). For IH, anti-MHC I and anti-synaptofisin antibodies were used, conjugated with CY2 or CY3 secondary antibodies and analyzed with a confocal microscope. The results showed a significant increased expression of MHC I in AIJ strain in comparison to Balb/cJ and C57BL/6J, 1 week after axotomy. Nevertheless, the immunoreactivity levels of this molecule 3 weeks after axotomy did not differ among the studied mice strains. Additionally, a conspicuous decrease of synaptofisin expression in A/J mice was observed 1 week after sciatic transection. Similarly to the MHC I immunolabelirlg, 3 weeks after lesion, ali mice strains showed similar levels of synaptofisin expression. The results from TEM 1 week after lesion showed a lower synaptic covering in AIJ mice in comparison to Balb/cJ and C57BL/6J, although 3 weeks after axotomy C57BL/6J displayed a lower synaptic covering, while AIJ and Balb/cJ strains recovered their afferents, We conclude that the levei of MHC I expression influences the synaptic elimination process and possibly contributes to the regenerative potencial of the axotomized neurons / Doutorado / Anatomia / Doutor em Biologia Celular e Estrutural