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Oldfield, Nigel Leigh. "Thiazole-containing natural and non-natural metal-complexing agents." Thesis, University of Nottingham, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.311763.
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Sugimoto, Kenichi. "Mechanisms of antifatigue agents used in natural rubber." Thesis, Aston University, 1995. http://publications.aston.ac.uk/9755/.
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A large number of compounds containing quinonoid or hindered phenol functions were examined for their roles as antifatigue agents. Among the evaluated quinones and phenols expected to have macroalkyl radical scavenging ability, BQ, TOC, TOC and GM showed relatively good performance for fatigue resistance (although their performance was slightly less effective than the commercial aromatic amine antioxidants, IPPD and 6PPD). The compounds which were shown to have higher reactivity with alkyl radicals (via calculated reactivity indices) showed better fatigue resistance. This fact supports the suggestion that strong alkyl radical scavengers should be also effective antifatigue agents. Evidence produced based on calculation of reactivity indices suggests that the quinones examined react with alkyl radicals on the meta position of the quinone rings producing phenoxyl radicals. The phenoxyl radicals are expected either to disproportionate, to recombine with a further alkyl radical, or to abstract a hydrogen from another alkyl radical producing an olefine. The regeneration of quinones and formation of the corresponding phenols is expected to occur during the antifatigue activity. The phenol antioxidant, HBA is expected to produce a quinonoid compound and this is also expected to function in a similar way to other quinones. Another phenol, GM, which is also known to scavenge alkyl radicals showed good antifatigue performance. Tocopherols had effective antifatigue activity and are expected to have different antifatigue mechanisms from that of other quinones, hence TOC was examined for its mechanisms during rubber fatiguing using HPLC analysis. Trimers of TOC which were produced during vulcanisation are suggested to contribute to the fatigue activity observed. The evidence suggests that the trimers reproduce TOC and a mechanism was proposed. Although antifatigue agents evaluated showed antifatigue activity, most of them had poor thermoxidative resistance, hence it was necessary to compensate for this by using a combination of antioxidants with the antifatigue agents.
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Pan, Ende. "Searching for Anticancer Agents and Antimalarial Agents from Madagascar." Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/77260.
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In our continuing search for biologically active natural products from Madagascar as part of an International Cooperative Biodiversity Group (ICBG) program, a total of four antiproliferative extracts were studied, leading to the isolation of twelve novel compounds with antiproliferative activity against the A2780 human ovarian cancer line, and one extract with antimalarial activities was studied, which led to the isolation of five new natural products with antimalarial activities against the Dd2 and HB3 malarial parasites.
The plants and their metabolites are discussed in the following order: one new xanthone and two known guttiferones from Symphonia tanalensis Jum. & H. Perrier (Clusiaceae); four new diphenyl propanes and one new cyclohepta-dibenzofuran skeleton from Bussea sakalava (Fabaceae); four new cardiac glycosides from Leptadenia madagascariensis Decne. (Apocynaceae); two new and four known alkaloids from Ambavia gerrardii (Baill.) Le Thomas (Annonaceae); five new sesquiterpene lactones from Polycline proteiformis Humbert (Asteraceae).
The structures of all compounds were determined by analysis of their mass spectrometric, 1D and 2D NMR, UV and IR spectroscopic and optical rotation data. Other than structure elucidation, this dissertation also involve bioactivity evaluation of all the isolates, synthesis of two interesting alkaloids, as well as a proposal for the possible biosynthetic pathway of the new cyclohepta-dibenzofuran skeleton.Ph. D.
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Burgess, René G. "Realistic evaluation of terrain by intelligent natural agents (RETINA) /." Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2003. http://library.nps.navy.mil/uhtbin/hyperion-image/03sep%5FBurgess.pdf.
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Thesis (M.S. in Modeling, Virtual Environments and Simulation)--Naval Postgraduate School, September 2003.Thesis advisor(s): Chris Darken, John Hiles. Includes bibliographical references (p. 87-90). Also available online.
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Shah, Aashay Kirit. "Development of novel anticancer agents based on natural products." Diss., University of Iowa, 2015. https://ir.uiowa.edu/etd/5993.
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My thesis includes the development of two novel anticancer agents based on natural products; OSW-1 analog (ZJ-201) and truncated Superstolide A analog (ZJ-102).
OSW-1 is isolated from the bulbs of Ornithogalum saundersiae. It exhibits an extremely potent anticancer activity against a wide spectrum of cancer cells. Relatively, its anticancer activities are about 10-100 times more potent than many well-known anticancer drugs in clinical use. However, the promise of OSW-1 is dampened by its relatively weak in vivo anticancer activity. We hypothesize that the loss of two ester groups on OSW-1 in mouse causes a discrepancy in its in vivo efficacy. Therefore, replacing both ester groups in the disaccharide portion of OSW-1 with bioisosteric amides should significantly reduce the rate of metabolism and greatly improve its in vivo anticancer activity. This dissertation includes the synthesis of amide analog of OSW-1, ZJ-201. The synthetic route described in this thesis is characterized by its flexibility to synthesize multiple amino analogs of OSW-1. ZJ-201 will be evaluated for its in vitro cytotoxicity, metabolic stability and pharmacokinetic properties. The biological data obtained will enable us to get insights into the SAR of OSW-1 and assist in transforming OSW-1 into a clinically agent.
Superstolide A is a highly potent anticancer agent isolated from marine sponge Neosiphonia superstes. In 2013, Jin’s lab reported the design and synthesis of truncated Superstolide A (ZJ-101) in 15 steps with a yield of 6.2%. In vitro cytotoxicity studies showed that ZJ-101 maintains and sometimes exceeds the potent anticancer activity of the parent natural product. As this is the first active analog of Superstolide A reported, there is a need to develop additional analogs of ZJ-101 to probe into the SAR of this anticancer agent. This dissertation includes the synthesis of aromatic analog of truncated Superstolide A, ZJ-102. In vitro cytotoxicity studies showed that ZJ-201 demonstrated poor antiproliferative properties in comparison to ZJ-101. Hence, we can conclude that the cyclohexene ring of ZJ-101 cannot be simplified to an aromatic core as it significantly affects anticancer activity.
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Hans, Renate Hazel. "Novel Antimalarial and Antitubercular Agents Based on Natural Products." Doctoral thesis, University of Cape Town, 2009. http://hdl.handle.net/11427/6311.
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Malaria and tuberculosis are listed among the major infectious diseases. They are responsible for severe morbidity and mortality especially in resource-poor settings where control interventions are inaccessible, unaffordable and plagued by widespread resistance. According to current estimates, malaria afflicts over 40% of the worldâs population and claims the lives of 1-3 million annually. The epidemiology of tuberculosis is just as grim. About one third of the world population is reported to be infected with Mycobacterium tuberculosis and it is responsible for 2-3 million deaths annually. Of particular interest to this project, is the fact that natural products have always been on the frontline in the battle against these diseases, that is, most of the clinically used drugs in antimalarial and antitubercular chemotherapy are of natural product-origin. In this project we therefore focussed on the design, synthesis, characterization and biological evaluation of novel antimalarial and antitubercular agents obtained by synthetically hybridizing and decorating scaffolds based on natural products or derivatives - with a history in the aforementioned disease models. Scaffolds selected include the thiolactone ring system, a key intermediate of the natural product thiolactomycin, the non-peptidic natural product isatin and the chalcone scaffold. In this way a series of hybrids were constructed which can be subdivided into three main groups: (i) thiolactone-isatin hybrids, (ii) -amino alcohol thiolactone-chalcone and isatin-chalcone hybrids, and (iii) dihydroartemisinin-isatin, dihydroartemisinin-chalcones and other miscellaneous hybrids. These were evaluated for antiplasmodial activity against the chloroquine resistant (W2) and chloroquine sensitive (D10) strains of Plasmodium falciparum as well as for inhibitory activity against cysteine proteases. Evaluation of antimycobacterial activity of the synthesized compounds against the drug sensitive H37Rv strain of M. tuberculosis was also undertaken. (i) For the first group of hybrids we used the C-4 hydroxyl group of the thiolactone ring as a handle for functionalization by attaching it via a variable, non-hydrolyzable alkyl linker to the isatin scaffold. Most striking, is the operational simplicity of the synthesis methodology employed and how it led to the discovery of a novel tetracyclic ring system. Identified from the latter is the compound 3.8p which is the most active antimalarial from this series with an IC50 of 6.92 μM in the W2 strain. Some of the hybrids (3.7 and 3.8) were more active than the monomers and the parent drug thiolactomycin, thus demonstrating the potential of hybridization as a drug discovery tool. Antimalarial structure activity relationships for the novel tetracycles 3.8 revealed the importance of substitution at C-5 of the isatin scaffold and vi the need for increased lipophilicity. Although the antitubercular activity of the hybrids was inferior compared to the control drugs, a number of advanced intermediates were identified which displayed promising activity against both fast growing and slow-growing, persistent forms of M. tuberculosis. (ii) The second group of hybrids consisted of a 36-member library obtained by the covalent linkage of methoxylated chalcones with the thiolactone ring and the isatin scaffold. Incorporated in their design is the -amino alcohol moiety, a known bioactiphore. For the synthesis of these hybrids we employed the copper-catalyzed Huisgen 1,3-dipolar cycloaddition reaction (also know as âclickâ chemistry) which in addition to expediting structure activity relationship studies yielded the 1,2,3-triazole ring system. The antiplasmodial results showed that the thiolactone-chalcones, with IC50s ranging from 0.68 to 6.08 μM, were more active against the W2 strain than the isatin-chalcones (IC50 = 2.09 - 14.90 μM). More so, structure activity relationships delineated for the former indicated the preference for triOMe substitution on ring A of the chalcone scaffold. The most active compound for this series 4.14f [IC50 = 0.68 μM (W2)] is 10-fold less active than chloroquine but has a greater efficacy than the parent natural product thiolactomycin. Results obtained for cysteine protease activity showed that the isatin-chalcone hybrids inhibited falcipain-2 activity, whereas the thiolactone-chalcone hybrids were devoid of enzyme inhibitory activity. With regard to antitubercular activity, the advanced intermediates were more active than the hybrid constructs. The most promising antitubercular agent identified is the acetylenic chalcone 4.10f (MIC = 13.1 μM) which is 2-fold more active than one of the controls, moxifloxacin (MIC = 31.1 μM) against the slow-growing persistent forms of M. tuberculosis. (iii) The final group of compounds is a limited series of semi-synthetic artemisinin analogues obtained by hybridizing the first generation analogue, dihydroartemisinin with previously mentioned scaffolds (isatin, chalcones, thiolactone) and other biologically relevant scaffolds such as the 4-aminoquinoline unit and azidovudine (AZT). As with the previous series we utilized the âclickâ reaction to effect the synthesis of these hybrids. The most active compound identified is the intermediate 5.4 [IC50 = 6.13 nM (W2)] which is more active than the parent natural product artemisinin [IC50 = 10.84 nM (W2)], 16 times more active than chloroquine and 2-times less active than dihydroartemisinin. The lack of antitubercular activity of compounds in this series moreover confirmed the antimalarial specificity of artemisinin analogues.
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Burgess, Rene G. "Realistic evaluation of terrain by intelligent natural agents (RETINA)." Thesis, Monterey, California. Naval Postgraduate School, 2003. http://hdl.handle.net/10945/867.
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Approved for public release; distribution is unlimitedUS Army and Joint constructive simulations require human operators to observe the exercise in progress, conduct analysis of the results, and provide a realistic reports and assessment of the action presented on their screens to the desired training audience. Current software tools provide excellent mathematical assessments (such as center of mass calculations, optimal routes, and sensor ranges) but poor human-like assessment of data (most likely route, probable enemy intention, etc.). This Thesis presents an artificial intelligence architecture specifically designed to reduce that manpower requirement by describing a concept for computer modeling that can produce realistic human-like assessment results. Specific concepts described are approaches for conducting a digital terrain assessment, development of avenues of approach, deployment of templated forces to a specific piece of terrain, and then a method of adjusting the templated force to react to actual sightings and known information. Also included are more detailed discussions and implementation details for use of gas diffusion as a method of analyzing avenues of approach through digital terrain. This approach seems quite promising as a method of modeling human movement tendencies and appears superior to classic path finding or optimal route selection methods.
Lieutenant Colonel, United States Army
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Kanyanda, Stonard Sofiel Elisa. "Screening of natural products and Alkylating agents for Antineoplastic Activity." Thesis, University of the Western Cape, 2007. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_6433_1363357514.
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Background and objectives: Apoptosis is a process in which a cell programmes its own death. It is a highly organized physiological mechanism in which injured or damaged cells are destroyed. Apart from physiological stimuli however, exogenous factors can induce apoptosis. Many anti-cancer drugs work by activating apoptosis in cancer cells. Natural substances have been found to have the ability to induce apoptosis in various tumour cells and these substances have been used as templates for the construction of
novel lead compounds in anticancer treatment. On the other hand, alkylating agents such as cisplatin, cis- [PtCl2 (NH3) 2] have been widely used as antineoplastic agents for a
wide variety of cancers including testicular, ovarian, neck and head cancers, amongst others. However, the use of cisplatin as an anticancer agent is limited due to toxicity and resistance problems. The aim of this present study was to screen the leaves of Rhus laevigata, a South African indigenous plant, for the presence of pro-apoptotic and
anti-proliferative natural compounds and also to screen newly synthesised palladium based complexes (15 and 57) and a platinum based complex (58) for their antineoplastic
activities tested against a panel of cell lines. Results. The results showed that crude methanol extracts from Rhus laevigata as well as the newly synthesised palladium based complexes (15 and 57) and a platinum based complex (58) induced apoptosis in the cell lines tested, as demonstrated by the externalization of phosphatidylserine, mitochondrial membrane permeabilization,caspase-3 activation, and DNA fragmentation. Caski (cervical cancer) and H157 (non small cell lung carcinoma) cell lines treated with the methanol extract from Rhus laevigata however, were more resistant to apoptosis induction. Among the metallocomplexes, complexes 15 and 57, palladium based complexes, were the most active. Conclusion: The methanol extract from the leaves of Rhus laevigata contain pro-apoptotic and antiproliferative natural compound(s), which need to be characterised and elucidated as they could provide the much-needed lead compounds in the fight against cancer. On the other hand the newly synthesized palladium complexes also need further evaluation to
see if they can be used as anticancer agents that can overcome the problems associated with cisplatin.
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Pierce, Tyler. "Virtual Interactions with Real-Agents for Sustainable Natural Resource Management." Master's thesis, University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/6002.
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Common pool resource management systems are complex to manage due to the absence of a clear understanding of the effects of users' behavioral characteristics. Non-cooperative decision making based on individual rationality (as opposed to group rationality) and a tendency to free ride due to lack of trust and information about other users' behavior creates externalities and can lead to tragedy of the commons without intervention by a regulator. Nevertheless, even regulatory institutions often fail to sustain natural common pool resources in the absence of clear understanding of the responses of multiple heterogeneous decision makers to different regulation schemes. While modeling can help with our understanding of complex coupled human-natural systems, past research has not been able to realistically simulate these systems for two major limitations: 1) lack of computational capacity and proper mathematical models for solving distributed systems with self-optimizing agents; and 2) lack of enough information about users' characteristics in common pool resource systems due to absence of reliable monitoring information. Recently, different studies have tried to address the first limitation by developing agent-based models, which can be appropriately handled with today's computational capacity. While these models are more realistic than the social planner's models which have been traditionally used in the field, they normally rely on different heuristics for characterizing users' behavior and incorporating heterogeneity. This work is a step-forward in addressing the second limitation, suggesting an efficient method for collecting information on diverse behavioral characteristics of real agents for incorporation in distributed agent-based models. Gaming in interactive virtual environments is suggested as a reliable method for understanding different variables that promote sustainable resource use through observation of decision making and behavior of the resource system beneficiaries under various institutional frameworks and policies. A review of educational or "serious" games for environmental management was undertaken to determine an appropriate game for collecting information on real-agents and also to investigate the state of environmental management games and their potential as an educational tool. A web-based groundwater sharing simulation game—Irrigania—was selected to analyze the behavior of real agents under different common pool resource management institutions. Participants included graduate and undergraduate students from the University of Central Florida and Lund University. Information was collected on participants' resource use, behavior and mindset under different institutional settings through observation and discussion with participants. Preliminary use of water resources gaming suggests communication, cooperation, information disclosure, trust, credibility and social learning between beneficiaries as factors promoting a shift towards sustainable resource use. Additionally, Irrigania was determined to be an effective tool for complementing traditional lecture-based teaching of complex concepts related to sustainable natural resource management. The different behavioral groups identified in the study can be used for improved simulation of multi-agent groundwater management systems.M.S.
Masters
Civil, Environmental, and Construction Engineering
Engineering and Computer Science
Civil Engineering; Water Resources Engineering
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SAYAO, MIRIAM. "REQUIREMENTS VERIFICATION AND VALIDATION: NATURAL LANGUAGE PROCESSING AND SOFTWARE AGENTS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2007. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=10927@1.
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COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIORPONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO GRANDE DO SUL
No processo de desenvolvimento do software, atividades relacionadas ao Processo de Requisitos envolvem elicitação, modelagem, verificação e validação dos requisitos. O uso da linguagem natural no registro dos requisitos facilita a comunicação entre os participantes do processo, além de possibilitar que clientes e usuários validem requisitos sem necessitar de conhecimento extra. Por outro lado, na economia globalizada atual, o desenvolvimento de software por equipes geograficamente distribuídas está se tornando uma norma. Nesse cenário, atividades de verificação e validação de requisitos para um software de média ou alta complexidade podem envolver o tratamento de centenas ou milhares de requisitos. Com essa ordem de complexidade é importante que o engenheiro de software tenha apoio computacional para o desempenho adequado das atividades de aferição de qualidade. Neste trabalho estamos propondo uma estratégia que combina técnicas de processamento da linguagem natural (PLN) e agentes de software para apoiar as atividades de análise dos requisitos. Geramos visões textuais ou gráficas de grupos de requisitos relacionados; visões apóiam a análise de completude, a identificação de duplicidades e de dependências entre requisitos. Utilizamos técnicas de análise de conteúdo para apoiar a identificação de omissões em requisitos não funcionais. Também propomos uma estratégia para a construção ou atualização do léxico da aplicação, utilizando técnicas de PLN. Utilizamos agentes de software para implementar serviços que incorporam as estratégias referidas, e também para atuar como representantes dos participantes do projeto em desenvolvimento.
In software development process, initial activities can involve requirements elicitation, modeling and analysis (verification and validation). The use of natural language in the register of the requirements facilitates the communication among stakeholders, besides offering possibilities to customers and users to validate requirements without extra knowledge. On the other hand, in the current global economy, software development for teams geographically distributed is becoming a rule. In this scenario, requirements verification and validation for medium or high complexity software can involve the treatment of hundreds or even thousand requirements. With this complexity order it is important to provide computational support for the software engineer execute quality activities. In this work we propose a strategy which combines natural language processing (NLP) techniques and software agents to support analysis activities. We have generated textual or graphical visions from groups of related requirements; visions help completeness analysis, identification of duplicities and dependences among requirements. We use content analysis techniques to support the identification of omissions in nonfunctional requirements. Also, we propose a strategy to construct the lexicon, using NLP techniques. We use software agents to implement web services that incorporate the related strategies, and also agents to act as personal assistants for stakeholders of the software project.
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Almaliti, Jehad S. "Natural Products-Inspired Synthesis and Biological Evaluation of Bioactive Agents." University of Toledo Health Science Campus / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=mco1384555204.
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Smith, Dustin Ryan. "Studies of natural and synthetic anti-inflammatory compounds." Oklahoma City : [s.n.], 2004.
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Shuter, Emily Clare. "Studies toward the synthesis of the microsclerodermin natural products." Connect to full text, 2005. http://ses.library.usyd.edu.au/handle/2123/1970.
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Thesis (Ph. D.)--University of Sydney, 2006.Title from title screen (viewed April 1, 2008). Submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy to the School of Chemistry, Faculty of Science. Degree awarded 2006; thesis submitted 2005. Includes bibliographical references. Also available in print form.
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Chambers, Mark Geoffrey. "The development of natural murine osteoarthritis : a quantitative cytochemical study." Thesis, Brunel University, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.260285.
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Abbas, Shah Rukh. "Preliminary investigation of natural materials for use in ultrasound contrast agents." Thesis, University of Cambridge, 2014. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708316.
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Ameh, Ekwu Mark. "The use of bacteriophages as natural biocontrol agents against bacterial pathogens." Thesis, Cranfield University, 2016. http://dspace.lib.cranfield.ac.uk/handle/1826/11331.
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Bacteriophages are viruses that specifically infect bacteria. The bactericidal nature of lytic bacteriophages has been exploited by scientists for decades with the hope to utilise them in the fight against bacterial infections and antibiotic resistant bacteria in medical settings. More recently, the potential applications of bacteriophages for biocontrol in the agrifood and environmental sectors have been investigated in an attempt to develop ‘natural’ antimicrobial products. Bacteriophages have a couple of decisive advantages over conventional methods of controlling pathogenic bacteria, such as high host specificity, the ability to self-replicate, and the ability to evolve with their hosts. However, more research is needed to optimise the parameters for phage applications, including the impact of environmental conditions on lysis efficiency, multiplicity of infection, and to significantly minimise the emergence of bacterial resistance to phages. Temperature plays a key role in every biological activity in nature. It is also assumed that temperature has an effect on phage lysis efficiency. A comprehensive study of it and how it affects both the host cells and their corresponding phages is crucial to ensure the efficient removal of bacterial pathogens. In this thesis, temperature (as selected parameter) was investigated to determine its influence on the lysis effectiveness of the three different phages belonging to the family of the Myoviridea that were isolated and purified from a single water sample taken from a brook receiving treated wastewater. We used the multiplicity of infection of 1 in all of our study in this project. Temperature was found to have a significant impact on phage-mediated lysis efficiency. Both the temperature of incubation of the phage-bacteria mixture (incubation temperature) and the temperature history of bacterial hosts were found to have profound effects on plaque sizes as well as plaque numbers. Plaque size and number decreased with increasing temperature. For the phages examined, bacterial lysis was more efficient at 20°C compared to 30 or 37°C. Phages were suggested to be well adapted to the environment where they were isolated from with general implications for use in biological disinfection. Furthermore, the temperature history of the bacteria (prior to phage encounter) was found to have a modulating effect on their susceptibility to lysis. A second part of this study compared the performance of the three phages in regard to bacterial resistance. The emergence of bacterial resistance is a major obstacle to the success of bacteriophages applications. The use of multiple phages is typically recommended and has proven better than the use of a single phage. However, the bestway to perform phage treatment is still very unclear. This study therefore compared simultaneous addition of multiple phages (in form of a cocktail) with the sequential addition of the individual phages at different time points in trying to delay the emergence of bacterial resistance. The data obtained from this work suggest that lysis effectiveness can be adjusted to optimize any treatment goal. For fast initial bacterial clearance the use of a single phage with short time maximal lysis efficiency proved most efficient, while the simultaneous addition of phages in the form of a cocktail was most successful strategy in our study. Addition of selected phages sequentially can be normalized in such a way that is just as effective as a cocktail. A third part of this thesis looked into the susceptibility of bacteria that had undergone sublethal disinfection. We addressed the question whether bacteria subjected to sublethal doses of chlorine and UV are still susceptible to phage-mediated lysis. The chlorine treatments indicated the development of a phage-insensitive phenotype for a critical chlorine dose in the transition zone between live and dead. The remaining live (and culturable) bacteria were shown insensitive to the selected phage. The lowest UV exposure at 2.8 mJ/cm2 eliminated bacteria susceptibility to the phages. This phage- resistant phenotype may have serious consequences for the application of phages on foods or water that have previously undergone a weak disinfection regime.
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Mohammad, Yasser Farouk Othman. "Autonomous development of natural interactive behavior for robots and embodied agents." 京都大学 (Kyoto University), 2009. http://hdl.handle.net/2433/126468.
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Kyoto University (京都大学)0048
新制・課程博士
博士(情報学)
甲第14970号
情博第362号
新制||情||67(附属図書館)
27408
UT51-2009-M884
京都大学大学院情報学研究科知能情報学専攻
(主査)教授 西田 豊明, 教授 乾 敏郎, 教授 山本 章博, 准教授 尾形 哲也
学位規則第4条第1項該当
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Harsh, Philip R. "Applications of asymmetric allylation reactions towards natural product synthesis." Morgantown, W. Va. : [West Virginia University Libraries], 2008. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=6029.
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Thesis (M.S.)--West Virginia University, 2008.Title from document title page. Document formatted into pages; contains vi, 78 p. : ill. Includes abstract. Includes bibliographical references (p. 37-38).
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au, os goh@murdoch edu, and Ong Sing Goh. "A framework and evaluation of conversation agents." Murdoch University, 2008. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20081020.134601.
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This project details the development of a novel and practical framework for the development of conversation agents (CAs), or conversation robots. CAs, are software programs which can be used to provide a natural interface between human and computers. In this study, conversation refers to real-time dialogue exchange between human and machine which may range from web chatting to on-the-go conversation through mobile devices. In essence, the project proposes a smart and effective communication technology where an autonomous agent is able to carry out simulated human conversation via multiple channels. The CA developed in this project is termed Artificial Intelligence Natural-language Identity (AINI) and AINI is used to illustrate the implementation and testing carried out in this project. Up to now, most CAs have been developed with a short term objective to serve as tools to convince users that they are talking with real humans as in the case of the Turing Test. The traditional designs have mainly relied on ad-hoc approach and hand-crafted domain knowledge. Such approaches make it difficult for a fully integrated system to be developed and modified for other domain applications and tasks. The proposed framework in this thesis addresses such limitations. Overcoming the weaknesses of previous systems have been the key challenges in this study. The research in this study has provided a better understanding of the system requirements and the development of a systematic approach for the construction of intelligent CAs based on agent architecture using a modular N-tiered approach. This study demonstrates an effective implementation and exploration of the new paradigm of Computer Mediated Conversation (CMC) through CAs. The most significant aspect of the proposed framework is its ability to re-use and encapsulate expertise such as domain knowledge, natural language query and human-computer interface through plug-in components. As a result, the developer does not need to change the framework implementation for different applications. This proposed system provides interoperability among heterogeneous systems and it has the flexibility to be adapted for other languages, interface designs and domain applications. A modular design of knowledge representation facilitates the creation of the CA knowledge bases. This enables easier integration of open-domain and domain-specific knowledge with the ability to provide answers for broader queries. In order to build the knowledge base for the CAs, this study has also proposed a mechanism to gather information from commonsense collaborative knowledge and online web documents. The proposed Automated Knowledge Extraction Agent (AKEA) has been used for the extraction of unstructured knowledge from the Web. On the other hand, it is also realised that it is important to establish the trustworthiness of the sources of information. This thesis introduces a Web Knowledge Trust Model (WKTM) to establish the trustworthiness of the sources.
In order to assess the proposed framework, relevant tools and application modules have been developed and an evaluation of their effectiveness has been carried out to validate the performance and accuracy of the system. Both laboratory and public experiments with online users in real-time have been carried out. The results have shown that the proposed system is effective. In addition, it has been demonstrated that the CA could be implemented on the Web, mobile services and Instant Messaging (IM). In the real-time human-machine conversation experiment, it was shown that AINI is able to carry out conversations with human users by providing spontaneous interaction in an unconstrained setting. The study observed that AINI and humans share common properties in linguistic features and paralinguistic cues. These human-computer interactions have been analysed and contributed to the understanding of how the users interact with CAs. Such knowledge is also useful for the development of conversation systems utilising the commonalities found in these interactions. While AINI is found having difficulties in responding to some forms of paralinguistic cues, this could lead to research directions for further work to improve the CA performance in the future.
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Valli, Marilia [UNESP]. "Nubbe natural products, source of molecular diversity for the design of new anticancer agents." Universidade Estadual Paulista (UNESP), 2014. http://hdl.handle.net/11449/110702.
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000796531.pdf: 5589932 bytes, checksum: 23400d4937d9c4df5a1ed4c87d102fff (MD5)Os produtos naturais são uma importante fonte de inspiração para o desenvolvimento de novos fármacos. O presente trabalho visou identificar produtos naturais bioativos que pudessem ser usados como modelo para o planejamento de novos compostos com propriedades antitumorais. A falta de dados organizados é ainda uma das dificuldades das áreas de produtos naturais e química medicinal. Portanto, a compilação de dados disponíveis sobre os metabólitos secundários sejam de espécies vegetais ou de outras fontes é de grande valor. Esse fato nos motivou a propor como primeiro objetivo deste projeto, a criação de uma base de dados contendo informações botânicas, químicas e biológicas dos metabólitos secundários obtidos e publicados pelo NuBBE durante 15 anos. A base de dados poderá ser útil não apenas para a pesquisa em química de produtos naturais atual do grupo, mas para todos interessados em estudos de planejamento de moléculas bioativas, metabolômica e dereplication, já que está disponível para acesso livre na internet. Um artigo científico descrevendo a criação da base de dados foi publicado na revista Journal of Natural Products em 2013. Os compostos da base de dados foram utilizados como fonte de moléculas para uma triagem virtual baseada na estrutura do receptor com a proteína tubulina para a identificação de moduladores dessa proteína. Baseado nos resultados de triagem virtual foi realizada a avaliação biológica in vitro das substâncias utilizando a proteína tubulina e ensaios de migração celular (wound healing e câmara de Boyden). Os ensaios biológicos indicaram uma série de guanidinas e a piplartina como principais compostos bioativos dentre os avaliados. A piplartina foi selecionada como modelo para o planejamento de novos compostos, pois apresentou relevante inibição de migração celular, além de estar descrito na literatura como citotóxico e...
Natural products are an important source for the design of new drugs. This thesis aimed at the identification of bioactive natural products to be used as models for the design of compounds with antitumor properties. The lack of organized data is still one of the drawbacks in the natural products and medicinal chemistry area. Therefore, the compilation of accessible data of secondary metabolites from plant species or other sources is of great value, especially for the identification of molecular leads. This fact inspired us to propose as first objective of this thesis, the creation of the NuBBE database (NuBBEDB) containing botanical, chemical, and biological information of the secondary metabolites obtained and published by NuBBE in 15 years. This database can be useful not only for the current research in natural products of the group, but for the scientific society interested in bioactive compounds, metabolomics, and dereplication. A scientific paper describing the creation of the database was published in the Journal of Natural Products in 2013. NuBBEDB compounds were used as molecular source for the virtual screening with the protein tubulin. Based on the results of the virtual screening the biological evaluation of selected compounds was performed with the protein tubulin, and cell migration assays (Wound Healing and Boyden Chamber). The results of the biological assays indicated a series of guanidines and piplartine as active compounds. Piplartine was selected to be a model for the design of new compounds because it inhibited cell migration and is described in the literature as cytotoxic and selective, an interesting profile for this project. A series of 5 analogue compounds were designed and synthesized aiming at a better understanding of structure activity relationship and improvement of the biological activity. The compound designed by molecular simplification showed activity in the cell...
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Valli, Marilia. "Nubbe natural products, source of molecular diversity for the design of new anticancer agents /." Araraquara, 2014. http://hdl.handle.net/11449/110702.
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Orientador: Vanderlan da Silva BolzaniCo-orientador: Adriano Defini Andricopulo
Banca: Ian Castro-Gamboa
Banca: Flávio da Silva Emery
Banca: Norberto Peporine Lopes
Banca: Sylvie Michel
Resumo: Os produtos naturais são uma importante fonte de inspiração para o desenvolvimento de novos fármacos. O presente trabalho visou identificar produtos naturais bioativos que pudessem ser usados como modelo para o planejamento de novos compostos com propriedades antitumorais. A falta de dados organizados é ainda uma das dificuldades das áreas de produtos naturais e química medicinal. Portanto, a compilação de dados disponíveis sobre os metabólitos secundários sejam de espécies vegetais ou de outras fontes é de grande valor. Esse fato nos motivou a propor como primeiro objetivo deste projeto, a criação de uma base de dados contendo informações botânicas, químicas e biológicas dos metabólitos secundários obtidos e publicados pelo NuBBE durante 15 anos. A base de dados poderá ser útil não apenas para a pesquisa em química de produtos naturais atual do grupo, mas para todos interessados em estudos de planejamento de moléculas bioativas, metabolômica e dereplication, já que está disponível para acesso livre na internet. Um artigo científico descrevendo a criação da base de dados foi publicado na revista Journal of Natural Products em 2013. Os compostos da base de dados foram utilizados como fonte de moléculas para uma triagem virtual baseada na estrutura do receptor com a proteína tubulina para a identificação de moduladores dessa proteína. Baseado nos resultados de triagem virtual foi realizada a avaliação biológica in vitro das substâncias utilizando a proteína tubulina e ensaios de migração celular (wound healing e câmara de Boyden). Os ensaios biológicos indicaram uma série de guanidinas e a piplartina como principais compostos bioativos dentre os avaliados. A piplartina foi selecionada como modelo para o planejamento de novos compostos, pois apresentou relevante inibição de migração celular, além de estar descrito na literatura como citotóxico e...
Abstract: Natural products are an important source for the design of new drugs. This thesis aimed at the identification of bioactive natural products to be used as models for the design of compounds with antitumor properties. The lack of organized data is still one of the drawbacks in the natural products and medicinal chemistry area. Therefore, the compilation of accessible data of secondary metabolites from plant species or other sources is of great value, especially for the identification of molecular leads. This fact inspired us to propose as first objective of this thesis, the creation of the NuBBE database (NuBBEDB) containing botanical, chemical, and biological information of the secondary metabolites obtained and published by NuBBE in 15 years. This database can be useful not only for the current research in natural products of the group, but for the scientific society interested in bioactive compounds, metabolomics, and dereplication. A scientific paper describing the creation of the database was published in the Journal of Natural Products in 2013. NuBBEDB compounds were used as molecular source for the virtual screening with the protein tubulin. Based on the results of the virtual screening the biological evaluation of selected compounds was performed with the protein tubulin, and cell migration assays (Wound Healing and Boyden Chamber). The results of the biological assays indicated a series of guanidines and piplartine as active compounds. Piplartine was selected to be a model for the design of new compounds because it inhibited cell migration and is described in the literature as cytotoxic and selective, an interesting profile for this project. A series of 5 analogue compounds were designed and synthesized aiming at a better understanding of structure activity relationship and improvement of the biological activity. The compound designed by molecular simplification showed activity in the cell...
Doutor
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Wilkens, Rodrigo Souza. "A study of the use of natural language processing for conversational agents." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2016. http://hdl.handle.net/10183/142158.
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linguagem é uma marca da humanidade e da consciência, sendo a conversação (ou diálogo) uma das maneiras de comunicacão mais fundamentais que aprendemos quando crianças. Por isso uma forma de fazer um computador mais atrativo para interação com usuários é usando linguagem natural. Dos sistemas com algum grau de capacidade de linguagem desenvolvidos, o chatterbot Eliza é, provavelmente, o primeiro sistema com foco em diálogo. Com o objetivo de tornar a interação mais interessante e útil para o usuário há outras aplicações alem de chatterbots, como agentes conversacionais. Estes agentes geralmente possuem, em algum grau, propriedades como: corpo (com estados cognitivos, incluindo crenças, desejos e intenções ou objetivos); incorporação interativa no mundo real ou virtual (incluindo percepções de eventos, comunicação, habilidade de manipular o mundo e comunicar com outros agentes); e comportamento similar ao humano (incluindo habilidades afetivas). Este tipo de agente tem sido chamado de diversos nomes como agentes animados ou agentes conversacionais incorporados. Um sistema de diálogo possui seis componentes básicos. (1) O componente de reconhecimento de fala que é responsável por traduzir a fala do usuário em texto. (2) O componente de entendimento de linguagem natural que produz uma representação semântica adequada para diálogos, normalmente utilizando gramáticas e ontologias. (3) O gerenciador de tarefa que escolhe os conceitos a serem expressos ao usuário. (4) O componente de geração de linguagem natural que define como expressar estes conceitos em palavras. (5) O gerenciador de diálogo controla a estrutura do diálogo. (6) O sintetizador de voz é responsável por traduzir a resposta do agente em fala. No entanto, não há consenso sobre os recursos necessários para desenvolver agentes conversacionais e a dificuldade envolvida nisso (especialmente em línguas com poucos recursos disponíveis). Este trabalho foca na influência dos componentes de linguagem natural (entendimento e gerência de diálogo) e analisa em especial o uso de sistemas de análise sintática (parser) como parte do desenvolvimento de agentes conversacionais com habilidades de linguagem mais flexível. Este trabalho analisa quais os recursos do analisador sintático contribuem para agentes conversacionais e aborda como os desenvolver, tendo como língua alvo o português (uma língua com poucos recursos disponíveis). Para isto, analisamos as abordagens de entendimento de linguagem natural e identificamos as abordagens de análise sintática que oferecem um bom desempenho. Baseados nesta análise, desenvolvemos um protótipo para avaliar o impacto do uso de analisador sintático em um agente conversacional.Language is a mark of humanity and conscience, with the conversation (or dialogue) as one of the most fundamental manners of communication that we learn as children. Therefore one way to make a computer more attractive for interaction with users is through the use of natural language. Among the systems with some degree of language capabilities developed, the Eliza chatterbot is probably the first with a focus on dialogue. In order to make the interaction more interesting and useful to the user there are other approaches besides chatterbots, like conversational agents. These agents generally have, to some degree, properties like: a body (with cognitive states, including beliefs, desires and intentions or objectives); an interactive incorporation in the real or virtual world (including perception of events, communication, ability to manipulate the world and communicate with others); and behavior similar to a human (including affective abilities). This type of agents has been called by several terms, including animated agents or embedded conversational agents (ECA). A dialogue system has six basic components. (1) The speech recognition component is responsible for translating the user’s speech into text. (2) The Natural Language Understanding component produces a semantic representation suitable for dialogues, usually using grammars and ontologies. (3) The Task Manager chooses the concepts to be expressed to the user. (4) The Natural Language Generation component defines how to express these concepts in words. (5) The dialog manager controls the structure of the dialogue. (6) The synthesizer is responsible for translating the agents answer into speech. However, there is no consensus about the necessary resources for developing conversational agents and the difficulties involved (especially in resource-poor languages). This work focuses on the influence of natural language components (dialogue understander and manager) and analyses, in particular the use of parsing systems as part of developing conversational agents with more flexible language capabilities. This work analyses what kind of parsing resources contributes to conversational agents and discusses how to develop them targeting Portuguese, which is a resource-poor language. To do so we analyze approaches to the understanding of natural language, and identify parsing approaches that offer good performance, based on which we develop a prototype to evaluate the impact of using a parser in a conversational agent.
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Chang, Gary C. "Ecological interaction among natural enemies and its consequences for biological control /." Thesis, Connect to this title online; UW restricted, 2000. http://hdl.handle.net/1773/5205.
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Guichard, Jonathan. "Quality Assessment of Conversational Agents : Assessing the Robustness of Conversational Agents to Errors and Lexical Variability." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-226552.
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Assessing a conversational agent’s understanding capabilities is critical, as poor user interactions could seal the agent’s fate at the very beginning of its lifecycle with users abandoning the system. In this thesis we explore the use of paraphrases as a testing tool for conversational agents. Paraphrases, which are different ways of expressing the same intent, are generated based on known working input by performing lexical substitutions and by introducing multiple spelling divergences. As the expected outcome for this newly generated data is known, we can use it to assess the agent’s robustness to language variation and detect potential understanding weaknesses. As demonstrated by a case study, we obtain encouraging results as it appears that this approach can help anticipate potential understanding shortcomings, and that these shortcomings can be addressed by the generated paraphrases.Att bedöma en konversationsagents språkförståelse är kritiskt, eftersom dåliga användarinteraktioner kan avgöra om agenten blir en framgång eller ett misslyckande redan i början av livscykeln. I denna rapport undersöker vi användningen av parafraser som ett testverktyg för dessa konversationsagenter. Parafraser, vilka är olika sätt att uttrycka samma avsikt, skapas baserat på känd indata genom att utföra lexiska substitutioner och genom att introducera flera stavningsavvikelser. Eftersom det förväntade resultatet för denna indata är känd kan vi använda resultaten för att bedöma agentens robusthet mot språkvariation och upptäcka potentiella förståelssvagheter. Som framgår av en fallstudie får vi uppmuntrande resultat, eftersom detta tillvägagångssätt verkar kunna bidra till att förutse eventuella brister i förståelsen, och dessa brister kan hanteras av de genererade parafraserna.
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Elvir, Miguel. "EPISODIC MEMORY MODEL FOR EMBODIED CONVERSATIONAL AGENTS." Master's thesis, University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3000.
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Embodied Conversational Agents (ECA) form part of a range of virtual characters whose intended purpose include engaging in natural conversations with human users. While works in literature are ripe with descriptions of attempts at producing viable ECA architectures, few authors have addressed the role of episodic memory models in conversational agents. This form of memory, which provides a sense of autobiographic record-keeping in humans, has only recently been peripherally integrated into dialog management tools for ECAs. In our work, we propose to take a closer look at the shared characteristics of episodic memory models in recent examples from the field. Additionally, we propose several enhancements to these existing models through a unified episodic memory model for ECAÂ s. As part of our research into episodic memory models, we present a process for determining the prevalent contexts in the conversations obtained from the aforementioned interactions. The process presented demonstrates the use of statistical and machine learning services, as well as Natural Language Processing techniques to extract relevant snippets from conversations. Finally, mechanisms to store, retrieve, and recall episodes from previous conversations are discussed. A primary contribution of this research is in the context of contemporary memory models for conversational agents and cognitive architectures. To the best of our knowledge, this is the first attempt at providing a comparative summary of existing works. As implementations of ECAs become more complex and encompass more realistic conversation engines, we expect that episodic memory models will continue to evolve and further enhance the naturalness of conversations.M.S.Cp.E.
School of Electrical Engineering and Computer Science
Engineering and Computer Science
Computer Engineering MSCpE
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Goh, Ong Sing. "A framework and evaluation of conversation agents." Goh, Ong Sing (2008) A framework and evaluation of conversation agents. PhD thesis, Murdoch University, 2008. http://researchrepository.murdoch.edu.au/752/.
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This project details the development of a novel and practical framework for the development of conversation agents (CAs), or conversation robots. CAs, are software programs which can be used to provide a natural interface between human and computers. In this study, ‘conversation’ refers to real-time dialogue exchange between human and machine which may range from web chatting to “on-the-go” conversation through mobile devices. In essence, the project proposes a “smart and effective” communication technology where an autonomous agent is able to carry out simulated human conversation via multiple channels. The CA developed in this project is termed “Artificial Intelligence Natural-language Identity” (AINI) and AINI is used to illustrate the implementation and testing carried out in this project. Up to now, most CAs have been developed with a short term objective to serve as tools to convince users that they are talking with real humans as in the case of the Turing Test. The traditional designs have mainly relied on ad-hoc approach and hand-crafted domain knowledge. Such approaches make it difficult for a fully integrated system to be developed and modified for other domain applications and tasks. The proposed framework in this thesis addresses such limitations. Overcoming the weaknesses of previous systems have been the key challenges in this study. The research in this study has provided a better understanding of the system requirements and the development of a systematic approach for the construction of intelligent CAs based on agent architecture using a modular N-tiered approach. This study demonstrates an effective implementation and exploration of the new paradigm of Computer Mediated Conversation (CMC) through CAs. The most significant aspect of the proposed framework is its ability to re-use and encapsulate expertise such as domain knowledge, natural language query and human-computer interface through plug-in components. As a result, the developer does not need to change the framework implementation for different applications. This proposed system provides interoperability among heterogeneous systems and it has the flexibility to be adapted for other languages, interface designs and domain applications. A modular design of knowledge representation facilitates the creation of the CA knowledge bases. This enables easier integration of open-domain and domain-specific knowledge with the ability to provide answers for broader queries. In order to build the knowledge base for the CAs, this study has also proposed a mechanism to gather information from commonsense collaborative knowledge and online web documents. The proposed Automated Knowledge Extraction Agent (AKEA) has been used for the extraction of unstructured knowledge from the Web. On the other hand, it is also realised that it is important to establish the trustworthiness of the sources of information. This thesis introduces a Web Knowledge Trust Model (WKTM) to establish the trustworthiness of the sources.
In order to assess the proposed framework, relevant tools and application modules have been developed and an evaluation of their effectiveness has been carried out to validate the performance and accuracy of the system. Both laboratory and public experiments with online users in real-time have been carried out. The results have shown that the proposed system is effective. In addition, it has been demonstrated that the CA could be implemented on the Web, mobile services and Instant Messaging (IM). In the real-time human-machine conversation experiment, it was shown that AINI is able to carry out conversations with human users by providing spontaneous interaction in an unconstrained setting. The study observed that AINI and humans share common properties in linguistic features and paralinguistic cues. These human-computer interactions have been analysed and contributed to the understanding of how the users interact with CAs. Such knowledge is also useful for the development of conversation systems utilising the commonalities found in these interactions. While AINI is found having difficulties in responding to some forms of paralinguistic cues, this could lead to research directions for further work to improve the CA performance in the future.
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Lucena, Percival Silva de. ""SemanticAgent, uma plataforma para desenvolvimento de agentes inteligentes"." Universidade de São Paulo, 2003. http://www.teses.usp.br/teses/disponiveis/55/55134/tde-01082003-102927/.
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Agentes inteligentes é um termo guarda-chuva que agrega diversas pesquisas no desenvolvimento de softwares autônomos que utilizam técnicas de Inteligência Artificial a fim de satisfazer metas estabelecidas por seus usuários. A construção de sistemas baseados em agentes inteligentes é uma tarefa complexa que envolve aspectos como comunicação entre agentes, planejamento, divisão de tarefas, coordenação, representação e manipulação de conhecimento e comportamentos, entre outras tarefas. Plataformas para agentes prevêem alguns serviços que permitem a desenvolvedores construir soluções sem a necessidade de se preocupar com todos detalhes da implementação. Um novo modelo para criação de agentes chamado 'agentes atômicos' é proposto com o objetivo de oferecer flexibilidade para o gerenciamento de conhecimento e implementação de comportamentos. A arquitetura Agentes Semânticos provê um framework para a implementação de tal modelo, oferecendo um conjunto de ferramentas para a criação de agentes inteligentes. Um protótipo de plataforma para agentes, baseado em tal arquitetura, foi desenvolvido em Java e permite a criação de aplicações capazes de processar linguagem natural restrita, manipular conhecimento e executar ações úteis.Intelligent Agents is an umbrella term that aggregates different research on the development of autonomous software that uses Artificial Intelligence techniques in order to satisfy user requests. The construction of systems based on intelligent agents is a complex task that involves aspects such as agent communication, planning, work division, cooperation, epresentation and manipulation of knowledge,among other activities. Agent Platforms provide some services that allow developers to build solutions without the need of worrying about every implementation detail. A new model for creating agents, called 'atomic agents', is proposed with the goal of offering flexible knowledge management and behavior implementation for constructing software agents. The Semantic AgentArchitecture provides a framework for the implementation of such model, offering a set of tools for the creation of intelligent agents. A prototype Agent Platform, based on the architecture, was developed in Java and allows the creation of applications that are able to process restricted natural language, manipulate knowledge and execute useful actions.
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Sheth, Ritesh B. "Development of new synthetic methodologies and the synthesis of natural products." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 101 p, 2010. http://proquest.umi.com/pqdweb?did=1993336351&sid=2&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Pung, Thitiya. "The Isolation of Natural Products From Plant Extracts." Thesis, Virginia Tech, 2000. http://hdl.handle.net/10919/33973.
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Bioassay-guided fractionation of the ethyl acetate extract of Virola sp.
(Myristicaceae) using the Sc7 yeast strain resulted in the isolation of the weakly cytotoxic
biochanin A (an isoflavone compound). The bioassay of three mutant yeast strains
(1138, 1104, and 1353) directed the isolation of DNA-damaging alkaloids from Solanum
hostmannii. These alkaloids were identified as verazine and (20R) epimer verazine. In
addition, three oxoaporphine alkaloids were isolated from the bark of Papualthia sp.
(Annonaceae). Oxocrebanine and atherospermidine showed DNA-damaging activity
whereas liriodenine had cytotoxic activity.Master of Science
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Straub, Cory Severen. "Exploring the relationship between natural enemy biodiversity and herbivore suppression." Online access for everyone, 2006. http://www.dissertations.wsu.edu/Dissertations/Fall2006/c_straub_111306.pdf.
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Guasch, Pàmies Laura. "Identification of natural products as antidiabetic agents using computer-aided drug design methods." Doctoral thesis, Universitat Rovira i Virgili, 2011. http://hdl.handle.net/10803/111094.
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Els productes naturals derivats de plantes són una font abundant de compostos biològicament actius, molts dels quals han servit de base pel desenvolupament de productes nutracèutics i farmacèutics. El disseny de fàrmacs assistit per ordinador juga un paper essencial en la identificació de productes naturals bioactius, reduint els costos i esforços experimentals. La diabetis mellitus tipus 2 és considerada com "l’epidèmia del segle 21" i, en conseqüència, és un dels principals reptes en el descobriment de fàrmacs en l'actualitat. Per tant, aquesta tesi doctoral es centra en la identificació de nous compostos i extractes naturals que actuïn com a agents antidiabètics. En aquest sentit, PPARgamma i DPP-IV han estat les dianes estudiades, en les quals s’han desenvolupat i validat diferents protocols de cribatge virtual. Els compostos bioactius trobats poden ser de gran utilitat com additius en l’alimentació funcional adreçada en la prevenció o tractament de la diabetis.Natural products derived from medicinal plants are an abundant source of biologically active compounds, many of which have formed the basis for development of nutraceuticals and pharmaceuticals compounds. Computer-aided drug design methods such as virtual screening workflows play an essential role in the identification of undescribed bioactivities of natural products by minimizing the synthetic and biological testing efforts. Type 2 diabetes mellitus (T2DM) is considered to be the “epidemic of the 21st century” and, consequently, is one of the main challenges in drug discovery today. There is a significant unmet medical need for better drugs to treat T2DM because some therapies suffer undesirable side effects. Therefore, this PhD thesis is focus on the identification of new natural compounds as antidiabetic agents. In that sense, PPARgamma and DPP-IV have shown to be appropriate targets for antidiabetic drugs, targeting them appears to have good prospects for a successful therapeutic approach in the T2DM.
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Rees, Daniel J. "Natural and synthetic GHSR1a agonists as neuroprotective agents in models of Parkinson's disease." Thesis, Swansea University, 2017. https://cronfa.swan.ac.uk/Record/cronfa40946.
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Parkinson’s disease (PD) is the second most prevalent neurodegenerative disorder in humans. It is characterised by the progressive loss of the A9 (Girk2+) subpopulation of dopamine (DA) neurones in the Substantia Nigra Pars Compacta (SNpc) resulting in resting tremor, bradykinesia and rigidity. The majority of PD cases are idiopathic. However, environmental toxins that inhibit the mitochondrial electron transport chain cause PD-like symptoms and recent studies of rare familial PD implicate metabolic dysfunction as a possible cause of DA nerve cell loss. We propose that the homeostatic hormone, acyl-ghrelin, may prevent DA neurone loss by preserving nerve cell metabolism during bioenergetics stress. In the in-vivo MPTP-toxin model of PD acyl-ghrelin prevents SNpc DA neurone loss in an acyl-ghrelin receptor (GHSR)-dependent manner (Andrews et al.2009). Here, using the eGFP-GHSR reporter mouse we demonstrate co-localised expression of the GHSR with TH+ and Girk2+ SNpc neurones. This suggests that acyl-ghrelin may exert a direct protective effect on A9 DA neurones via GHSR+ signalling. We show that acyl-ghrelin attenuated the 6-OHDA-induced SN lesion in unilateral lesioned rats. Moreover, this neuroprotection is consistent with the preservation of motor function. Using a mouse-midbrain-derived neuronal cell line (SN4741), immune-positive for TH+/ Girk2+/GHSR+, we assess the neuroprotective potential of acyl-ghrelin and GHSR1a agonist, JMV2894, in an in-vitro rotenone-based PD model. Furthermore, we show acyl-ghrelin as a modulator of intra-cellular AMPK and ACC phosphorylation and investigate the protective effects on mitochondrial health and morphology using automated images analysis and TEM. Acyl-ghrelin activated cellular pathways associated with protecting against energetic stress and promoting healthy aging. These data suggest that Acyl-Ghrelin may be a potential new therapeutic target for PD.
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Gunewardena, J. Anoma G. S. G. "Development and evaluation of dispersing agents for carbon black filled natural rubber compounds." Thesis, Loughborough University, 1999. https://dspace.lboro.ac.uk/2134/32245.
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Various additions are used in rubber compounds to accelerate mixing with particulate fillers and to improve behaviour in subsequent processing operations. Cationic surfactants of general structure [RNH2(CH2)3NH3]2+ 2[R'COO] can be used in rubber processing as multifunctional additives (MFA) which act as processing aids, accelerators and mould releasing agents. However, with all these beneficial properties an adverse effect of decreased scorch time was observed when N–tallow–1,3 diaminopropane dioleate (EN444) was used in the filled natural rubber compound.
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Schwartz, Eric Brandon. "The Synthesis and Optimization of Bioactive Natural Products as Anticancer and Antileishmanial Agents." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1436964192.
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Egieyeh, Samuel Ayodele. "Computational strategies to identify, prioritize and design potential antimalarial agents from natural products." University of the Western Cape, 2015. http://hdl.handle.net/11394/5058.
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Philosophiae Doctor - PhDIntroduction: There is an exigent need to develop novel antimalarial drugs in view of the mounting disease burden and emergent resistance to the presently used drugs against the malarial parasites. A large amount of natural products, especially those used in ethnomedicine for malaria, have shown varying in-vitro antiplasmodial activities. Facilitating antimalarial drug development from this wealth of natural products is an imperative and laudable mission to pursue. However, the limited resources, high cost, low prospect and the high cost of failure during preclinical and clinical studies might militate against pursue of this mission. Chemoinformatics techniques can simulate and predict essential molecular properties required to characterize compounds thus eliminating the cost of equipment and reagents to conduct essential preclinical studies, especially on compounds that may fail during drug development. Therefore, applying chemoinformatics techniques on natural products with in-vitro antiplasmodial activities may facilitate identification and prioritization of these natural products with potential for novel mechanism of action, desirable pharmacokinetics and high likelihood for development into antimalarial drugs. In addition, unique structural features mined from these natural products may be templates to design new potential antimalarial compounds. Method: Four chemoinformatics techniques were applied on a collection of selected natural products with in-vitro antiplasmodial activity (NAA) and currently registered antimalarial drugs (CRAD): molecular property profiling, molecular scaffold analysis, machine learning and design of a virtual compound library. Molecular property profiling included computation of key molecular descriptors, physicochemical properties, molecular similarity analysis, estimation of drug-likeness, in-silico pharmacokinetic profiling and exploration of structure-activity landscape. Analysis of variance was used to assess statistical significant differences in these parameters between NAA and CRAD. Next, molecular scaffold exploration and diversity analyses were performed on three datasets (NAA, CRAD and malarial data from Medicines for Malarial Ventures (MMV)) using scaffold counts and cumulative scaffold frequency plots. Scaffolds from the NAA were compared to those from CRAD and MMV. A Scaffold Tree was also generated for all the datasets. Thirdly, machine learning approaches were used to build four regression and four classifier models from bioactivity data of NAA using molecular descriptors and molecular fingerprints. Models were built and refined by leave-one-out cross-validation and evaluated with an independent test dataset. Applicability domain (AD), which defines the limit of reliable predictability by the models, was estimated from the training dataset and validated with the test dataset. Possible chemical features associated with reported antimalarial activities of the compounds were also extracted. Lastly, virtual compound libraries were generated with the unique molecular scaffolds identified from the NAA. The virtual compounds generated were characterized by evaluating selected molecular descriptors, toxicity profile, structural diversity from CRAD and prediction of antiplasmodial activity. Results: From the molecular property profiling, a total of 1040 natural products were selected and a total of 13 molecular descriptors were analyzed. Significant differences were observed between the natural products with in-vitro antiplasmodial activities (NAA) and currently registered antimalarial drugs (CRAD) for at least 11 of the molecular descriptors. Molecular similarity and chemical space analysis identified NAA that were structurally diverse from CRAD. Over 50% of NAA with desirable drug-like properties were identified. However, nearly 70% of NAA were identified as potentially "promiscuous" compounds. Structure-activity landscape analysis highlighted compound pairs that formed "activity cliffs". In all, prioritization strategies for the natural products with in-vitro antiplasmodial activities were proposed. The scaffold exploration and analysis results revealed that CRAD exhibited greater scaffold diversity, followed by NAA and MMV respectively. Unique scaffolds that were not contained in any other compounds in the CRAD datasets were identified in NAA. The Scaffold Tree showed the preponderance of ring systems in NAA and identified virtual scaffolds, which maybe potential bioactive compounds or elucidate the NAA possible synthetic routes. From the machine learning study, the regression and classifier models that were most suitable for NAA were identified as model tree M5P (correlation coefficient = 0.84) and Sequential Minimization Optimization (accuracy = 73.46%) respectively. The test dataset fitted into the applicability domain (AD) defined by the training dataset. The “amine” group was observed to be essential for antimalarial activity in both NAA and MMV dataset but hydroxyl and carbonyl groups may also be relevant in the NAA dataset. The results of the characterization of the virtual compound library showed significant difference (p value < 0.05) between the virtual compound library and currently registered antimalarial drugs in some molecular descriptors (molecular weight, log partition coefficient, hydrogen bond donors and acceptors, polar surface area, shape index, chiral centres, and synthetic feasibility). Tumorigenic and mutagenic substructures were not observed in a large proportion (> 90%) of the virtual compound library. The virtual compound libraries showed sufficient diversity in structures and majority were structurally diverse from currently registered antimalarial drugs. Finally, up to 70% of the virtual compounds were predicted as active antiplasmodial agents. Conclusions:Molecular property profiling of natural products with in-vitro antiplasmodial activities (NAA) and currently registered antimalarial drugs (CRAD) produced a wealth of information that may guide decisions and facilitate antimalarial drug development from natural products and led to a prioritized list of natural products with in-vitro antiplasmodial activities. Molecular scaffold analysis identified unique scaffolds and virtual scaffolds from NAA that possess desirable drug-like properties, which make them ideal starting points for molecular antimalarial drug design. The machine learning study built, evaluated and identified amply accurate regression and classifier accurate models that were used for virtual screening of natural compound libraries to mine possible antimalarial compounds without the expense of bioactivity assays. Finally, a good amount of the virtual compounds generated were structurally diverse from currently registered antimalarial drugs and potentially active antiplasmodial agents. Filtering and optimization may lead to a collection of virtual compounds with unique chemotypes that may be synthesized and added to screening deck against Plasmodium.
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McKerrecher, Darren. "Synthetic approaches to diene- and enyne-containing natural products of biological importance." Thesis, University of York, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.242186.
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Tanner, Justin Rogers. "Antimicrobial Producing Bacteria as Agents of Microbial Population Dynamics." Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/30038.
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The need for new antibiotics has been highlighted recently with the increasing pace of emergence of drug resistant pathogens (MRSA, XDR-TB, etc.). Modification of existing antibiotics with the additions of side chains or other chemical groups and genomics based drug targeting have been the preferred method of drug development at the corporate level in recent years. These approaches have yielded few viable antibiotics and natural products are once again becoming an area of interest for drug discovery.
We examined the antimicrobial â Red Soilsâ of the Hashemite Kingdom of Jordan that have historically been used to prevent infection and cure rashes by the native peoples. Antimicrobial producing bacteria were present in these soils and found to be the reason for their antibiotic activity. After isolation, these bacteria were found to excrete their antimicrobials into the liquid culture media which we could then attempt to isolate for further study. Adsorbent resins were employed to capture the antimicrobial compounds and then elute them in a more concentrated solution.
As part of a drug discovery program, we sought a way to quickly characterize other soils for potential antibiotic producing bacteria. The community level physiologic profile was examined to determine if this approach would allow for a rapid categorizing of soils based on their probability of containing antimicrobial producing microorganisms. This method proved to have a high level of variability that could not be overcome even after mixing using a commercial blender.
The role of these antimicrobial producing bacteria within their natural microbial community has largely been confined to microbe-plant interactions. The role of antimicrobial-producing microorganisms in driving the diversity of their community has not been a focus of considerable study. The potential of an antimicrobial-producing bacterium to act as a driver of diversity was examined using an artificial microbial community based in a sand microcosm. The changes in the microbial assemblage indicate that antimicrobial-producing bacteria may act in an allelopathic manner rather than in a predatory role.Ph. D.
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Syntrivanis, Leonidas-Dimitrios. "Synthesis of eleutherobin-like potential microtubule stabilising agents." Thesis, University of Oxford, 2017. https://ora.ox.ac.uk/objects/uuid:331f563e-efaf-453f-9920-9ae154048f72.
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This thesis describes synthetic studies towards the tricyclic terpene framework of the cytotoxic natural product eleutherobin, and the investigation of biocatalytic methodology towards late stage functionalisation of the structure. Chapter 1 provides an introduction to the biomedical significance of the natural product and to the various synthetic studies reported to date. Chapter 2 explores intramolecular Diels-Alder approaches to the construction of the nine- and six- membered rings present in the natural product. Chapter 3 describes alternative approaches to the eleutherobin core structure, leading to a formal synthesis of the natural product. The synthetic sequence developed is applied to the preparation of a small library of furanoid analogues of eleutherobin. Chapter 4 details the development of methodology for the one-pot preparation of (E)-4-methylhexa-3,5-dien-1-ol, and its use in an intermolecular Diels-Alder/lactonisation sequence to achieve enantioselective preparation of an important lactone building block. Chapter 5 describes studies on the mP450-mediated oxidation of various eleuthoside structures obtained. Finally, Chapter 6 details the construction of an electrochemical flow cell, and its use for the anodic oxidation of furfuryl alcohol derivatives.
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Salvaggio, Flavia. "Synthesis of biologically active quinolone natural products extracted from the actinomycete Pseudonocardia sp. CL38489." Thesis, University of Cambridge, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.648770.
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Bendiabdellah, Yassine. "Discovery of novel natural product based HIF-1a : HIF-1b inhibitors as potential anticancer agents." Thesis, University of London, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.528238.
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Scaduto, Ryan. "A Natural Product and High-Throughput Screening Synthetic Approach Towards the Discovery of Antileishmanial Agents." Ohio Dominican University Honors Theses / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=oduhonors1620081955401195.
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Dai, Yumin. "Isolation, Synthesis and Structure-Activity Relationship Study of Anticancer and Antimalarial Agents from Natural Products." Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/24193.
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The Kingston group's engagement in an International Cooperative Biodiversity Group (ICBG) program and a collaborative research project established between Virginia Tech and the Institute for Hepatitis and Virus Research (IHVR) has focused on the search for bioactive natural products from tropical forests in both Madagascar and South Africa. As a part of this research, a total of four antiproliferative extracts were studied, leading to the isolation of fourteen novel compounds with antiproliferative activity against the A2780 human ovarian cancer line. One extract with
antimalarial activity was studied, which led to the isolation of two new natural products with antiplasmodial activity against a drug-resistant Dd2 strain of Plasmodium falciparum.
The plants and their secondary metabolites are discussed in the following order: two new antiproliferative acetogenins from a Uvaria sp. (Annonaceae); two new antiproliferative calamenene-type sesquiterpenoids from Sterculia tavia (Malvaceae); two new antiproliferative triterpene saponins from Nematostylis anthophylla (Rubiaceae); six new antiproliferative homoisoflavonoids and two new bufatrienolides from Urginea depressa (Asparagaceae); and two
new antiplasmodial anthraquinones from Kniphofia ensifolia (Asphodelaceae).
The structures of all these compounds were determined by analysis of their mass spectrometric, 1D and 2D NMR, UV and IR spectroscopic and optical rotation data. Other than structural elucidation, this work also involved bioactivity evaluations of all the isolates, as well as total synthesis of the two antiproliferative sesquiterpenoids, and a structure-activity relationship (SAR) studies on the antiplasmodial anthroquinones.Ph. D.
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Poejo, Joana Margarida de Andrade. "Evaluation of Opuntia spp. bioactive products as promising natural chemotherapeutical agents- an in vitro approach." Master's thesis, Faculdade de Ciências e Tecnologia, 2011. http://hdl.handle.net/10362/6289.
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Dissertation to obtain a Master Degree in BiotechnologyRecently, prevention of cancer through dietary intervention has received an increasing interest. In particular, dietary polyphenols mainly found in fruits and vegetables have become very attractive as chemopreventive and therapeutic agents. The main aim of this work was to investigate the potential activity of Portuguese Opuntia spp. on colon cancer therapy, as this fruits have been reported to be rich sources of bioactive compounds. Opuntia spp. fruits were collected in different sites of Portugal, namely Tramagal, Beja, Marvão Sines and Quarteira and processed in order to obtain fruit juices, polyphenol-rich concentrates and residues extracts from fruit juices production. All Opuntia products were investigated for antiproliferative activity of human colon cancer cells (HT29). Opuntia juices from Tramagal, Sines and Quarteira were the most effective on cancer cell growth inhibition due to the highest content in total polyphenol content and betalains. The most promising extracts were derived from Quarteira, Sines and Beja fruit juices residues using conventional solvent extraction, adsorption technology and pressurized liquid extraction, respectively. These extracts showed high antiproliferative effect inducing cell cycle arrest in different checkpoints. Additionally, the same extracts showed to induce ROS production in cancer cells, playing an important role in activation of pro-apoptic cell death mechanisms. The capacity of natural extracts in reverting chemoresistance of tumor cells was evaluated on a drug-resistant HT29 cell culture. The product derived from Beja residue using pressurized liquid extraction with 60%CO2 and 40%EtOH showed to increase cells sensitivity to the drug. Opuntia spp. fruits reveled to be promising natural sources for the production of functional products as well as for the development of novel chemotherapeutic agents.
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Lee, John Ray. "Conversations with an intelligent agent-- modeling and integrating patterns in communications among humans and agents." Diss., University of Iowa, 2006. http://ir.uiowa.edu/etd/61.
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Edge, Mark. "Studies of potential intermediates for the total synthesis of the antitumor compound (+)-pancratistatin." Thesis, Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/27358.
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Kilama, John Jolly. "A new synthetic approach to the C-D ring portion of streptonigrin and its analogs." Diss., The University of Arizona, 1988. http://hdl.handle.net/10150/184620.
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Two new synthetic methods for the construction of the C-D moiety of streptonigrin have been developed. The first is the cyclization of beta, gamma unsaturated ketals to cyanopyridines. These ketals were prepared from akylidenemalononitriles. The second method utilized is the ortho-directed metalation of benzamide or oxazoline derivative to give keto compounds. However, attempts to transform these keto compounds to akylidenemalononitriles by Knoevenagel condensations were unsuccessful. With the ease of the reaction and ready availability of starting materials, the beta, gamma unsaturated ketals offer versatile synthons for pyridine C ring synthesis.
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Karkare, Sampada S. "Isolation and Structure Elucidation of Antiproliferative Agents From Madagascar Rainforests." Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/34945.
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Through our continuing search for anticancer agents from Madagascar rainforests as a part of International Cooperative Biodiversity Group (ICBG), we received two extracts which were active against the A2780 human ovarian cancer cell line and hence were selected for further fractionation. Six compounds were isolated from these extracts. The structure elucidation and characterization of these compounds was carried out using mass spectrometry and 1D and 2D NMR techniques.
The bioassay-guided fractionation of Roupellina (Strophanthus) boivinii yielded three new and one known cardenolide glycosides. The structure of the known cardenolide glycoside was determined after comparison of NMR data to that found in literature for digitoxigenin 3-O-β-D-glucopyranosyl-(1â 4)-α-L-acofriopyranoside. All four compounds exhibited good antiproliferative activity on the A2780 bioassay.
The fractionation of the extract of Grewia sp. led to the isolation of one new and one known triterpenoid. The known triterpenoid was identified as 7β-hydroxy-23-deoxojessic acid and its structure was confirmed by comparison of its 1D and 2D NMR data to that found in literature.Master of Science
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Frazão, Gladslene Góes Santos. "Elaboração de coberturas comestíveis à base de quitosana incorporadas com óleo essencial de Myrcia ovata Cambessedes com potencial para conservação de mangabas." Universidade Federal de Sergipe, 2016. https://ri.ufs.br/handle/riufs/3272.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPESThe edible coatings are defined as a thin layer of edible material usually applied in liquid form on the product by immersing the same. Several studies have shown that the addition of bioactive substances such as essential oils have increased antimicrobial packaging potential of these, contributing to the increased food shelf life. Thus, this study aimed to develop and evaluate in vitro and in situ microbiological efficiency of edible coatings to chitosan base incorporated with essential oils of Myrcia ovata Cambess (MYRO). The antimicrobial potential of 9 essential oils (EOs) was evaluated in vitro by diffusion technique in discs against foodborne bacteria (Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus cereus, Bacillus subtilis, Serratia marcescens, Escherichia coli, Enterococcus faecalis and Salmonella enteritidis). Due to greater availability of MYRO-174 and MYRO-175 oils and being gram-positive bacteria very sensitive to extremely sensitive to them, these were selected for incorporation into edible eatable coatings of chitosan base.The edible coatings formulations were prepared ranging cassava starch, chitosan and essential oil concentrations according the central composite rotational design (23 + 6 axial points and 3 central points). The bacteria were sensitive to edible coatings with diameters of inhibition zone between 9.0 -12.5 mm. The edible coatings formulations containing MYRO-175 oil were optimized for the B. Cereus and B. subtilis inhibition using the response surface methodology, a predictive mathematical model for the inhibition of them was obtained. The essential oil concentration was the more significant parameter to antimicrobial activity of coatings. The edible coatings incorporated with MYRO-174 oil or MYRO-175 (1.00% cassava starch, 1.00% chitosan and 1.25% essential oil) were applied in mangabas and the antimicrobial potential against natural microflora and Bacillus cereus artificially contaminated in the fruits was studied. The coated mangabas showed total mesophilic aerobic bacteria counts the order of 102 CFU/g, molds and yeasts <10 CFU/g (estimated value) and inhibition of growth of B. cereus for 12 days of storage at 10°C. On the other hand, uncoated mangabas (control) rotted from the 8th day of refrigerated storage. The edible coatings based in chitosan incorporated with M. ovata Cambess. EOs demonstrated potential to be used as an alternative in vitro microbiological control of foodborne bacteria and in situ on mangaba preservation.
As coberturas comestíveis são definidas como uma camada fina de material comestível, geralmente aplicada na forma líquida sobre o produto, por imersão do mesmo. Várias pesquisas têm demonstrado que a adição de substâncias bioativas como os óleos essenciais têm aumentado o potencial antimicrobiano destas embalagens contribuindo para o aumento da vida de prateleira de alimentos. Diante do exposto, o presente estudo teve como objetivo desenvolver e avaliar in vitro e in situ a eficiência microbiológica de coberturas comestíveis à base de quitosana incorporadas com óleos essenciais de Myrcia ovata Cambessedes (MYRO). O potencial antimicrobiano de 9 óleos essenciais foi avaliado in vitro através da técnica de difusão em discos frente à bactérias patogênicas de alimentos (Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus cereus, Bacillus subtilis, Serratia marcescens, Escherichia coli, Enterococcus faecalis e Salmonella enteritidis). Devido a maior disponibilidade dos óleos MYRO-174 e MYRO-175 e sendo as bactérias Gram-positivas de muito sensíveis a extremamente sensíveis aos mesmos, estes foram selecionados para a incorporação nas coberturas comestíveis a base de quitosana. As formulações de coberturas comestíveis foram elaboradas variando-se as concentrações de fécula de mandioca, quitosana e óleo essencial conforme o delineamento composto central rotacional (23 + 6 pontos axiais e 3 pontos centrais). As bactérias foram sensíveis às coberturas com halos de inbição entre 9,0 –12,5 mm. As formulações contendo o óleo MYRO-175 foram otimizadas para a inibição de B. cereus e B. subtilis utilizando a metodologia de superfície de resposta, sendo possível obter um modelo matemático preditivo para a inibição das mesmas. A concentração de óleo essencial foi o parâmetro significativo para a atividade antimicrobiana das coberturas. As coberturas comestíveis incorporadas com o óleo MYRO 174 ou MYRO-175 (1,0% de fécula de mandioca, 1,0% de quitosana e 1,25% de óleo essencial) foram aplicadas em mangabas e o potencial antimicrobiano foi avaliado frente a microbiota e ao Bacillus cereus artificialmente contaminado nos frutos. As mangabas revestidas com cobertura comestível apresentaram contagens de bactérias aeróbias mesófilas totais da ordem de 102 UFC/g, bolores e leveduras < 10 UFC/g (valor estimado) e inibição do crescimento de B. cereus por 12 dias de armazenamento a 10ºC. Já as mangabas sem revestimento (controle) apodreceram a partir do 8º dia de estocagem refrigerada. As coberturas comestíveis à base de quitosana incorporadas com óleos essenciais de M. ovata Cambessedes demonstraram potencial para serem utilizadas como alternativa no controle microbiológico in vitro de bactérias patogênicas de alimentos e in situ na conservação de mangabas.
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Cohen, Scott B. Myers Andrew G. Myers Andrew G. "Mechanistic studies of the natural DNA-cleaving agents neocarzinostatin chromophore, calicheamicin [gamma]1, and dynemicin A /." Diss., Pasadena, Calif. : California Institute of Technology, 1995. http://resolver.caltech.edu/CaltechETD:etd-09182007-090157.
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Devulder, Justine. "Régulation de la réaction asthmatique par des agents microbiens : quelle place pour les cellules natural killer ?" Thesis, Lille 2, 2019. http://www.theses.fr/2019LIL2S005/document.
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Cytotoxiques en lysant différents types de cellules et régulent la réponse immunitaire. Leur rôle dans l’asthme et ses exacerbations reste encore à identifier même si des modifications phénotypiques ont été observées chez des patients asthmatiques et qu’il a été récemment montré dans un modèle murin qu’elles n’intervenaient pas dans le développement de l’asthme allergique. L’objectif de la thèse était de mieux comprendre la place des cellules NK dans la pathologie asthmatique en se focalisant sur deux aspects : l’exacerbation viro-induite et l’inhibition par des composants microbiens.L’hypothèse pour la 1ère partie de la thèse était que les cellules NK de patients asthmatiques pouvaient présenter une dysfonction dans leur réponse à des agents microbiens qui pourrait favoriser l’exacerbation de la réaction asthmatique. Pour cela, nous avons analysé l’activation, la cytotoxicité et la production de cytokines de cellules NK provenant de patients asthmatiques sévères stimulées avec des molécules mimant des microorganismes ou un rhinovirus vivant (HRV), en comparaison avec des donneurs sains. Nous avons montré que les cellules NK de patients sévères étaient moins cytotoxiques que les cellules NK de donneurs sains en réponse à la stimulation avec un agoniste de Toll-Like Receptor 3 ou du TLR7/8 et avec HRV. En outre, lorsqu’elles sont stimulées avec de l’IL-12 et de l’IL-15, des cytokines produites pendant l’infection virale, les cellules NK de patients asthmatiques sévères expriment moins d’IFN-γ que les cellules NK de donneurs sains. Nos résultats suggèrent que l’activation des cellules NK de patients asthmatiques pourrait être insuffisante pendant les infections respiratoires et pourraient participer à l’aggravation de l’asthme.L’hypothèse pour la 2ème partie de la thèse était que les cellules NK pourraient participer à l’inhibition de la réaction asthmatique allergique dans un modèle murin. Dans des souris C57BL/6 sensibilisées à l’ovalbumine, l’instillation de FSL1, un agoniste de TLR2/6 inhibe la réaction asthmatique allergique. Cette inhibition étant associée à des modifications de la population des cellules NK, nous avons analysé leur rôle grâce à des souris déficientes en cellules NK. En l’absence de cellules NK, les souris développent un asthme allergique, et l’inhibition par FSL1 est maintenue. Par conséquent, les cellules NK ne jouent pas de rôle dans le développement de l’asthme allergique expérimental, ni dans son inhibition induite par un agent microbien. Cependant, elles pourraient être modifiées par l’environnement allergique, et avoir ainsi un rôle dans les exacerbation viro-induites. Cette question cruciale rejoint le travail réalisé dans la première partie de la thèse.En conclusion, nos résultats suggèrent que les fonctions des cellules NK seraient modifiées dans la pathologie asthmatique, qu’elle soit allergique ou non. Notre hypothèse est que le défaut d’activation des cellules NK participerait aux exacerbations viro-induites de l’asthme. Les perspectives de ces travaux sont de poursuivre la caractérisation des cellules NK chez les patients asthmatiques sévères et d’évaluer le rôle des cellules NK dans un modèle murin d’exacerbation de la réaction asthmatique.L’hypothèse pour la première partie de la thèse était que les cellules NK de patients asthmatiques pouvaient présenter une dysfonction dans leur réponse à des agents microbiens qui pourrait favoriser l’exacerbation de la réaction asthmatique. Pour cela, nous avons analysé l’activation, la cytotoxicité et la production de cytokines de cellules NK provenant de patients asthmatiques sévères stimulées avec des molécules mimant des microorganismes ou un rhinovirus vivant (HRV), en comparaison avec des donneurs sains. Nous avons montré que les cellules NK de patients sévères étaient moins cytotoxiques que les cellules NK de donneurs sains en réponse à la stimulation avec un agoniste de Toll-Like Receptor 3 ou du TLR7/8 et avec HRV [...]Asthma is a chronic inflammatory disease of the airways affecting 334 million of people worldwide. Among asthma patients, 5% suffers from severe asthma. Severe asthma represents a major unmet need because, despite heavy treatments, patients still suffer from uncontrolled asthma symptoms, frequent exacerbations and a dramatic decrease in their respiratory capacity. The role of microorganisms in asthma is complex. On one hand, a group of epidemiologic and experimental studies have shown that chronic exposure with bacteria or microbial compounds, particularly during early childhood, would provide protection against allergic asthma. On the other hand, respiratory viruses are responsible for 80% of exacerbations and are associated with an increasing risk of developing asthma in children, whether allergic or not. Natural Killer cells (NK) are lymphocytes involved in innate antiviral immunity. They have cytotoxic functions by lysing different types of cells but also regulatory functions by producing cytokines and activating other immune cells. Their role in asthma and its exacerbations has yet to be identified, although phenotypic changes have been observed in asthmatic patients and it has recently been shown in a mouse model that they are not involved in the development of allergic asthma. The objective of the thesis was to better understand the role of NK cells in asthmatic pathology by focusing on two aspects : virus-induced exacerbation and inhibition by microbial compounds.The hypothesis for the first part was that NK cells from asthma patients may present a dysfunction in their response to microbial agents that could promote the exacerbation of the asthmatic reaction. To do this, we analysed NK cell activation, cytotoxicity and production of cytokines from severe asthmatic patients stimulated with molecules mimicking microbes or a human rhinovirus (HRV), compared to healthy donors. We showed that NK cells from severe asthma patients were less cytotoxic than NK cells from healthy donors in response to stimulation with a Toll-like Receptor 3 or TLR7/8 agonist and HRV. Moreover, when stimulated with IL-12 and IL-15, cytokines produced during viral infections, NK cells from severe asthma patient express less IFN-γ than NK cells from healthy donors. Our results suggest that the activation of NK cells in asthma patients may be insufficient during respiratory infections and may contribute to the worsening of asthma.The hypothesis for the second part was that NK cells may participate to the inhibition of a mouse model of allergic asthma. In C57BL/6 mice sensitized with ovalbumin, instillation of FSL1, agonist of TLR2/6, inhibits the features of experimental asthma. Since this inhibition is associated with changes in the population of NK cells, we analysed their role using mice deficient in NK cells. In the absence of NK cells, mice develop allergic asthma, and inhibition by FSL1 is maintained. Therefore, NK cells do not play a role in the development of experimental allergic asthma or in its inhibition induced by a microbial agent. However, they may be modified by the allergic environment, and thus have a role in viro-induced exacerbations. This crucial question is in line with the work done in the first part of the thesis.In conclusion, our results suggest that the functions of NK cells may be modified in asthmatic pathology, whether allergic or not. Our hypothesis is that the defect in NK cell activation may participate to virus-induced asthma exacerbations. Perspectives of this work are to further characterize NK cells in severe asthma patients and to evaluate the role of NK cells in a mouse model of asthma exacerbation