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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Efeito do sistema ácido indol-3-acético/peroxidase de raiz forte sobre a viabilidade de Staphylococcus aureus / Effect of system indol-3-acetic acid/horseradish peroxidase on the viability of Staphylococcus aureus

Pugine, Silvana Marina Piccoli 19 March 2008 (has links)
O objetivo do presente estudo foi avaliar a ação do ácido indol-3-acético (AIA) combinado com a peroxidase de raiz forte (HRP), formando um sistema gerador de espécies reativas de oxigênio, sobre a viabilidade de Staphylococcus aureus. Para tal, avaliou-se a viabilidade do S. aureus através da contagem das unidades formadoras de colônias após crescimento em ágar manitol, potencial e integridade de membrana por citometria de fluxo e integridade do DNA através de eletroforese em gel de poliacrilamida. Para realização dos ensaios foram utilizadas cepas de S. aureus recuperadas de casos de mastites clínicas. As cepas foram cultivadas em meio BHI (brain-heart-infusion) a 37ºC \"overnight\". Nos ensaios, o microrganismo foi incubado na ausência (controle) e presença de AIA (1 mmol/L)/HRP (1 µmol/L) em diferentes tempos (0, 1,5, 3 e 6 horas) a 37ºC. Foram realizados também ensaios contendo o microrganismo incubado na presença de AIA ou de HRP. O sistema AIA/HRP inibiu em 96%, 98%, 99% a formação de colônias do microrganismo para os tempos de 1,5, 3 e 6 horas, respectivamente, em relação ao controle em cada tempo. Ocorreu uma redução na polarização da membrana do microrganismo em 38, 69 e 99% nos tempos 1,5, 3 e 6 horas, respectivamente e uma diminuição significativa do número de microrganismos com membrana integra de 17 e 22% quando estes foram incubados por 3 e 6 horas, respectivamente em relação ao controle nos respectivos tempos. A adição das enzimas antioxidantes catalase ou superóxido dismutase ao meio de incubação não alterou o efeito deletério promovido pelo sistema AIA/HRP avaliado pelas unidades formadoras de colônias, despolarização e integridade de membrana. O sistema AIA/HRP não induziu a fragmentação do DNA do S. aureus após 3 e 6 horas de incubação. No presente estudo, foi possível verificar que a oxidação do AIA pela HRP produz uma resposta citotóxica potente capaz de promover a inibição do crescimento de S. aureus em ágar manitol, provocar a despolarização e a perda da integridade da membrana do microrganismo, sugerindo a possibilidade da utilização do sistema AIA/HRP como uma possível terapia alternativa contra bactérias. / The objective of this study was to evaluate the action of the indole-3-acetic acid (IAA) in combination with horseradish peroxidase (HRP), forming a system generator of reactive oxygen species, on the viability of Staphylococcus aureus. To this end, was evaluated the of viability of S. aureus through the counting of the colony forming units after growth in mannitol agar, membrane potential and membrane integrity by flow cytometry and integrity of the DNA through the polyacrylamide gel electrophoresis. For the tests were used strains of S. aureus recovered from cases of clinical mastitis. The strains were grown in BHI medium (brain-heart-infusion) at 37°C overnight. In the tests, the microorganism was incubated in the absence (control) and presence of IAA (1 mmol/L)/HRP (1 µmol/L) at different times (0, 1.5, 3 and 6 hours) at 37°C. There were also conducted tests containing the microorganism incubated in the presence of IAA or HRP. The system IAA/HRP inhibited at 96%, 98%, 99% colony formation of microorganism to the times of 1.5, 3 and 6 hours, respectively, in relation to the control in every time. There was a decrease in polarization of the membrane of the microorganism on 38, 69 and 99% at times 1.5, 3 and 6 hours, respectively, and a significant decrease in the number of microorganisms with membrane integrity, 17 and 22% when they were incubated for 3 and 6 hours, respectively, in relation to the control in their time. The addition of the antioxidant enzymes catalase and superoxide dismutase in incubation medium did not alter the deleterious effect promoted by the system IAA/HRP assessed by colony forming units, membrane potential and membrane integrity. The system IAA/HRP did not induce the DNA fragmentation of S. aureus after 3 and 6 hours of incubation. In the present study, it was possible to verify that the oxidation of the IAA by HRP produces a potent cytotoxic response capable of promoting the inhibition of growth of S. aureus in mannitol agar, causing depolarization and the loss of integrity of the membrane of the microorganism, suggesting the possibility of using the system IAA/HRP as a possible alternative therapy against bacteria.
2

Efeito do sistema ácido indol-3-acético/peroxidase de raiz forte sobre a viabilidade de Staphylococcus aureus / Effect of system indol-3-acetic acid/horseradish peroxidase on the viability of Staphylococcus aureus

Silvana Marina Piccoli Pugine 19 March 2008 (has links)
O objetivo do presente estudo foi avaliar a ação do ácido indol-3-acético (AIA) combinado com a peroxidase de raiz forte (HRP), formando um sistema gerador de espécies reativas de oxigênio, sobre a viabilidade de Staphylococcus aureus. Para tal, avaliou-se a viabilidade do S. aureus através da contagem das unidades formadoras de colônias após crescimento em ágar manitol, potencial e integridade de membrana por citometria de fluxo e integridade do DNA através de eletroforese em gel de poliacrilamida. Para realização dos ensaios foram utilizadas cepas de S. aureus recuperadas de casos de mastites clínicas. As cepas foram cultivadas em meio BHI (brain-heart-infusion) a 37ºC \"overnight\". Nos ensaios, o microrganismo foi incubado na ausência (controle) e presença de AIA (1 mmol/L)/HRP (1 µmol/L) em diferentes tempos (0, 1,5, 3 e 6 horas) a 37ºC. Foram realizados também ensaios contendo o microrganismo incubado na presença de AIA ou de HRP. O sistema AIA/HRP inibiu em 96%, 98%, 99% a formação de colônias do microrganismo para os tempos de 1,5, 3 e 6 horas, respectivamente, em relação ao controle em cada tempo. Ocorreu uma redução na polarização da membrana do microrganismo em 38, 69 e 99% nos tempos 1,5, 3 e 6 horas, respectivamente e uma diminuição significativa do número de microrganismos com membrana integra de 17 e 22% quando estes foram incubados por 3 e 6 horas, respectivamente em relação ao controle nos respectivos tempos. A adição das enzimas antioxidantes catalase ou superóxido dismutase ao meio de incubação não alterou o efeito deletério promovido pelo sistema AIA/HRP avaliado pelas unidades formadoras de colônias, despolarização e integridade de membrana. O sistema AIA/HRP não induziu a fragmentação do DNA do S. aureus após 3 e 6 horas de incubação. No presente estudo, foi possível verificar que a oxidação do AIA pela HRP produz uma resposta citotóxica potente capaz de promover a inibição do crescimento de S. aureus em ágar manitol, provocar a despolarização e a perda da integridade da membrana do microrganismo, sugerindo a possibilidade da utilização do sistema AIA/HRP como uma possível terapia alternativa contra bactérias. / The objective of this study was to evaluate the action of the indole-3-acetic acid (IAA) in combination with horseradish peroxidase (HRP), forming a system generator of reactive oxygen species, on the viability of Staphylococcus aureus. To this end, was evaluated the of viability of S. aureus through the counting of the colony forming units after growth in mannitol agar, membrane potential and membrane integrity by flow cytometry and integrity of the DNA through the polyacrylamide gel electrophoresis. For the tests were used strains of S. aureus recovered from cases of clinical mastitis. The strains were grown in BHI medium (brain-heart-infusion) at 37°C overnight. In the tests, the microorganism was incubated in the absence (control) and presence of IAA (1 mmol/L)/HRP (1 µmol/L) at different times (0, 1.5, 3 and 6 hours) at 37°C. There were also conducted tests containing the microorganism incubated in the presence of IAA or HRP. The system IAA/HRP inhibited at 96%, 98%, 99% colony formation of microorganism to the times of 1.5, 3 and 6 hours, respectively, in relation to the control in every time. There was a decrease in polarization of the membrane of the microorganism on 38, 69 and 99% at times 1.5, 3 and 6 hours, respectively, and a significant decrease in the number of microorganisms with membrane integrity, 17 and 22% when they were incubated for 3 and 6 hours, respectively, in relation to the control in their time. The addition of the antioxidant enzymes catalase and superoxide dismutase in incubation medium did not alter the deleterious effect promoted by the system IAA/HRP assessed by colony forming units, membrane potential and membrane integrity. The system IAA/HRP did not induce the DNA fragmentation of S. aureus after 3 and 6 hours of incubation. In the present study, it was possible to verify that the oxidation of the IAA by HRP produces a potent cytotoxic response capable of promoting the inhibition of growth of S. aureus in mannitol agar, causing depolarization and the loss of integrity of the membrane of the microorganism, suggesting the possibility of using the system IAA/HRP as a possible alternative therapy against bacteria.
3

ENZYME CATALYZED SYNTHESIS IN IONIC LIQUIDS

Furlong, Danelle Lynn 13 September 2007 (has links)
No description available.
4

Disposable amperometric sensors for environmental monitoring

Chang, Seung Cheol January 2000 (has links)
No description available.
5

An HRP Study of the Spatial and Electrotonic Distribution of Group IA Synapses on Type-Identified Ankle Extensor Motoneurons in the Cat

Burke, R. E., Glenn, L. Lee 26 August 1996 (has links)
Eight functionally identified group Ia muscle afferents from triceps surae or plantaris muscles were labeled intraaxonally with horseradish peroxidase (HRP) in seven adult cats. Subsequently, HRP was injected into two to six homonymous or heteronymous alpha-motoneurons per animal (total = 22), each identified by motor unit type and located near the site of afferent injection. The complete trajectories of labeled afferents were reconstructed, and putative synaptic contacts on HRP-labeled motoneurons were identified at high magnification. Dendritic paths from each contact were also mapped and measured. A total of 24 contact systems (the combination of a group Ia afferent and a postsynaptic motoneuron) were reconstructed, of which 17 were homonymous, and seven were heteronymous. Overall, homonymous contact systems had an average of 9.6 boutons, whereas heteronymous contact systems had an average of 5.9 boutons. The average number of boutons found on type S motoneurons in homonymous contact systems was smaller (6.4, range 3-17) than in systems involving types FF or FR motoneurons (FF: 10.4, range 4-18; FR: 11.3, range 4-32). Neither of these differences were statistically significant. In contrast to earlier reports, a majority (15/24) of contact systems included more than one collateral from the same Ia afferent. The complexity (number of branch points) in the arborization pathway leading to each contact (overall mean 8.4 +/- 3.3) was virtually identical in all contact systems, irrespective of the type of postsynaptic motoneuron. The three-dimensional distribution of group Ia contacts was not coextensive with the radially organized dendrites of motoneurons: Dendrites oriented in the ventromedial to dorsolateral axis had the fewest (8%) contacts, whereas rostrocaudal dendrites had the most (63%) contacts. Nevertheless, contacts were widely distributed on the motoneuron surface, with few on and near the soma (< or = 200 microns radial distance from the soma) or on the most distal parts of the tree (> or = 1,000 microns). The boutons in individual contact systems also showed wide spatial and estimated electrotonic distributions; only 3/24 systems had all contact located within a restricted spatial/electrotonic region. The relations between these anatomical results and existing electrophysiological data on group Ia synaptic potentials are discussed.
6

Síntese de análogos da Licarina A para investigação da atividade tripanocida

Nelo, Romeu de Andrade January 2016 (has links)
Orientadora: Profª Drª Mirela Inês de Sairre / Dissertação (mestrado) - Universidade Federal do ABC. Programa de Pós-Graduação em Ciência e Tecnologia/Química, 2016. / In 1999, the natural product (-)-licarina A neolignan was isolated. Neolignans comprise a class of natural products with a great diversity of chemical structures and pharmacological activities, it is formed by coupling two units phenylpropanoids. This natural product has promising biological activity against the Trypanosoma cruzi and on the results, structure-activity relationship studies indicated the importance of obtaining new neolignans for investigation. This work describes the synthesis of neolignan (±)-licarina A through the oxidative coupling reaction catalyzed by the enzyme horseradish peroxidase (horseradish peroxidase - HRP). The reactions were performed using a methodology focused on "Green Chemistry", using green coconut water (Cocos nucifera L.) as a natural source of HRP enzyme. The phenylpropanoids substrates, isoeugenol, ferulic acid and nitrostyrene were prepared. Initially extraction was performed eugenol from clove, followed by isomerization in methanol and catalytic amount of palladium chloride (PdCl2) for obtaining isoeugenol in 90% yield. The Knoevenagel reaction of vanillin and malonic acid afforded the ferulic acid in 72% yield. The phenylpropanoid nitrostyrene was obtained from 4-hydroxybenzaldehyde, ammonium acetate and nitromethane, using micro-wave with 70% yield. Then the compounds isoeugenol, ferulic acid and nitrostyrene were subjected to oxidative coupling, using hydrogen peroxide and coconut water as a source of HRP. In all reactions, coconut has been opened for the use of water at the time of the experiments, and the end of the process, excess water was removed by lyophilization, which afforded minor amount of solvent for extraction. The results were promising in the search for new molecules obtained by this methodology. Neolignans were obtained with gross revenues of 30%, 85% and 78%, respectively, and will later be submitted to biological tests in order to evaluate the trypanocidal activity. / Em 1999, o produto natural (-)-licarina A, uma neolignana, foi isolada. As neolignanas compreendem uma classe de produtos naturais com uma grande diversidade de estruturas químicas e atividades farmacológicas, sendo formadas pelo acoplamento de duas unidades fenilpropanoides. Este produto natural apresentou atividade biológica promissora frente ao Trypanosoma cruzi e, diante dos resultados, estudos de relação estrutura-atividade indicaram a importância de obtenção de novas neolignanas para serem investigadas. Este trabalho descreve a síntese da neolignana (±)-licarina A através da reação de acoplamento oxidativo catalisada pela enzima peroxidase de raiz forte (horseradish peroxidase ¿ HRP). As reações foram realizadas empregando uma metodologia voltada para a "Química Verde", utilizando a água de coco verde (Cocos nucifera L.) como fonte natural da enzima HRP. Os substratos fenilpropanoides, isoeugenol, ácido ferúlico e nitroestireno foram preparados. Inicialmente foi realizada a extração do eugenol a partir do cravo-da-índia, seguida de isomerização em metanol e quantidade catalítica de cloreto de paládio (PdCl2), para obtenção do isoeugenol com 90% de rendimento. A reação de Knoevenagel entre a vanilina e o ácido malônico permitiu obter o ácido ferúlico com 72% de rendimento. O fenilpropanoide nitroestireno foi obtido a partir do 4-hidroxibenzaldeído, acetato de amônio e nitrometano, utilizando micro ondas com 70% de rendimento. Em seguida, os compostos isoeugenol, ácido ferúlico e nitroestireno, foram submetidos ao acoplamento oxidativo, utilizando peróxido de hidrogênio e água de coco como fonte de HRP. Em todas as reações, o coco foi aberto para a utilização da água no momento da realização dos experimentos e, ao final do processo, o excesso de água foi removido por liofilização, o que proporcionou menor quantidade de solvente para extração. Os resultados mostraram-se promissores para a busca de novas moléculas obtidas por esta metodologia. As neolignanas foram obtidas com rendimentos brutos de 30%, 85% e 78%, respectivamente e posteriormente, serão submetidas aos ensaios biológicos com o intuito de avaliar a atividade tripanocida.
7

Bioflocculation for Control of Wastewater Pond Microalgae

Frost, Daniel Thomas 01 December 2008 (has links)
Investigates several hypotheses regarding the use of bioflocculation as a harvesting method for wastewater pond microalgae. Research performed on pilot-scale high rate ponds (HRPs) on the California Central Coast.
8

Investigação dos efeitos dos procedimentos de imobilização em monocamadas auto-organizadas da enzima peroidase no desenvolvimento de um biossensor / Effects SAM on enzyme immobilization procedures in the peroxidase based biosensor performance

Mendes, Renata Kelly 13 December 2006 (has links)
Orientador: Lauro Tatsuo Kubota / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-10T12:02:32Z (GMT). No. of bitstreams: 1 Mendes_RenataKelly_D.pdf: 1152307 bytes, checksum: c6e7b97417285a7bb4d70d28ba880353 (MD5) Previous issue date: 2006 / Resumo: Neste trabalho foram investigados diferentes métodos de imobilização da enzima HRP empregando como matrizes as monocamadas auto-organizadas formadas sobre eletrodos de ouro, bem como a avaliação da influência do processo de imobilização do elemento biológico no desempenho analítico do biossensor. Para isso. as monocamadas utilizadas foram formadas por meio de tióis com diferentes estruturas, tamanho de suas cadeias carbônicas e grupos terminais. Foi possível constatar que o tamanho da cadeia carbônica de um tioI influencia especialmente no empacotamento da monocamada e, conseqüentemente, na eficácia da imobilização das biomoléculas. Pelos estudos realizados visando a caracterização das SAM sobre a superfície eletródica foi possível verificar que os tióis que possuem em sua cadeia um número menor de carbonos (< 9) tendem a formar monocamadas com uma quantidade considerável de defeitos na superfície do ouro, o que leva a um recobrimento mais baixo. No entanto, os tióis que contém um número mais elevado de carbonos na cadeia apresentam um grau de recobrimento mais elevado e, no entanto, não são boas matrizes para biossensores eletroquímicos, pois podem passivar a superfície, diminuindo a transferência de elétrons e, como conseqüência, a sensibilidade do eletrodo. Quanto a imobilização da enzima nos eletrodos de ouro, verificou-se, por diferentes técnicas, que as monocamadas que possuem grupo terminal -NH2 foram aquelas que proporcionaram os melhores resultados, provavelmente devido ao uso do glutaraldeído como ligante no processo de imobilização. Ao analisar adicionalmente o desempenho do biossensor para a determinação de peróxido de hidrogênio, verificou-se que a SAM formada pela cisteamina é a mais adequada para a imobilização da HRP, por propiciar tanto uma melhor eficácia na adsorção enzima quanto uma sensibilidade mais elevada para H2O2 / Abstract: In this work different immobilization procedures of HRP were investigated using as support mIatrices the self-assembled monolayers formed on gold electrodes, as well as the evaluation of the influence of these immobilization processes in the biosensor performance. For this, the used monolayers were prepared by thiols with different structures, carbon chains size and terminal groups. It was possible to have evidence that the thiol carbon chain size influences especially in the coverage monolayer and, consequently, in the efficiency of the biomolecule immobilization. From the studies carried out for the SAM characterization on the electrode surface it was possible to verify that thiols with smaller chain (n<9) trends to form monolayers with a considerable amount of defects on gold surface, that it leads to a lower coverage. However, the thiols with a higher carbon chain present a higher coverage degree, are not being good matrices for electrochemical biosensors, because it can passive the surface, making difficult the electron transfer and, consequently, the electrode sensitivity. In relation to the enzyme immobilization on gold electrodes it was verified, for different techniques, that monolayers that possess -NH2 terminal group provided the best results, probably due to the use of glutharaldeyde as ligant at the immobilization process. Analyzing the biosensor performance for the hydrogen peroxide determination was verified that SAM formed by cysteamine is more adequate for HRP immobilization, because provide the better efficiency in the enzyme immobilization associated to high sensitivity for H2O2 / Doutorado / Quimica Analitica / Doutor em Ciências
9

Retinal Terminals in the Goldfish Optic Tectum: Identification and Characterization

Airhart, Mark J., Kriebel, Richard M. 01 January 1984 (has links)
Retinal terminal profiles in the goldfish optic tectum were identified electron microscopically after (1) labeling with horseradish peroxidase and (2) in the early stages of degeneration in short‐term eye enucleates. All labeled terminals shared certain common morphological characteristics which were identical to those of a population of terminals in normal tecta. Terminals of this type disappeared 30 days after enucleation of the contralateral eye. Retinal terminal presynaptic profiles were characterized by (1) round and oval synaptic vesicles; (2) mitochondria with irregular, randomly oriented cristae, large intracristal spaces, dilated membrane spaces, and primarily light matrices; (3) a wide range in profile area, 0.06–6.82 μm2; (4) large numbers of synaptic vesicles per profile area 168± 33 synaptic vesicles per μm2; (5) asymmetric synapses; and (6) multiple synaptic contacts (1.46 ± 0.73 per terminal profile). The postsynaptic elements included both dendritic and, less commonly, pleomorphic vesicle‐containing profiles. The majority of postsynaptic dendritic profiles were small (0.01–0.40 μm2). Serial synaptic contacts were occasionally seen. The combination of vesicular and mitochondrial morphology (1 and 2 above) was necessary and sufficient to establish the retinal origin of a terminal, but use of such criteria would underestimate the number of retinotectal terminals by omitting those which did not have a mitochondrion in the plane of section. The number of such terminals was calculated from independent measurements, and the total number of retinal terminal profiles per area of neuropil was estimated.
10

Chefers hantering av fenomenet job hopping : En kvalitativ studie om hur chefer hanterar job hopping samt säkerställandet av organisationens kompetens / Managers’ handling of the phenomenon of job hopping : A qualitative study on how managers handle job hopping and ensuring the organization’s competence

Blom, Edvin, Hansemark, Louise January 2023 (has links)
Bakgrund: Arbetsmarknaden har förändrats och majoriteten av den personalomsättning som sker idag är så kallad frivillig omsättning. Dessa frekventa och frivilliga jobbyten har blivit känt som begreppet job hopping, vilket leder till att chefer måste hantera konsekvenserna av en hög personalomsättning. En hög personalomsättning leder vidare till ämnet kompetensförsörjning, vilket blir en avgörande del för organisationens fortsatta funktion. Syfte: Syftet med studien är att undersöka hur chefer hanterar fenomenet job hopping. Studien kommer att fokusera på att organisationen kan säkerställa att rätt kompetens finns och är konkurrenskraftig. Metod: Studien har tillämpats med en kvalitativ metod där semistrukturerade intervjuer genomförts för att besvara frågeställningen. Uppsatsen är byggd utifrån en tematisk analysmetod där citat från respondenterna valdes som koder för att identifiera teman. Genom intervjuerna har sedan empirin sammanställts. Empiri: I empirin presenteras respondenternas svar utifrån de gjorda intervjuerna, där de sammanställs av författarna i form av citat och kortare sammanfattningar. I den avslutande delen av empirin sammanställs en kortare summering av empiriavsnittet. Analys, diskussion och Slutsats: Empirin har sedan bearbetats i uppsatsens analysdikussion där den ställs emot den teoretiska referensramen. Slutsatsen belyser hur cheferna hanterar job hopping samt hur de påverkas eller ej, och leder sedan fram till att besvara frågeställningen. Vidare ges förslag till fortsatt forskning för att ytterligare studera ämnet. / Background: The labor market has changed and the majority of personnel turnover that occurs today is so-called voluntary turnover. These frequent and voluntary job changes have become known as the concept of job hopping, resulting in managers having to deal with the consequences of high staff turnover. A high staff turnover leads further to the subject of competence supply, which becomes a decisive part for the continued functioning of the organization. Purpose: The purpose of the study is to investigate how managers handle the phenomenon of job hopping. The study will focus on the organization being able to ensure that the right competence exists and is competitive. Method: The study has been applied with a qualitative method where semi-structured interviews were conducted to answer the question. The essay is based on a thematic analysis method where quotes from the respondents were chosen as codes to identify themes. The empirical evidence has then been compiled through the interviews. Empirics: In the empirics, the respondents' answers are presented based on the interviews conducted, where they are compiled by the authors in the form of quotes and shorter summaries. In the concluding part of the empirical work, a shorter summary of the empirical section is compiled. Analysis discussion and Conclusion: The empirical evidence has then been processed in the essay's analysis discussion, where it is set against the theoretical frame of reference. The conclusion highlights how managers handle job hopping and how they are affected or not, and then leads to answering the question. Furthermore, suggestions are given for further research to further study the subject.

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