• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 179
  • 166
  • 32
  • 28
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • 3
  • 2
  • 2
  • Tagged with
  • 563
  • 166
  • 84
  • 66
  • 56
  • 37
  • 36
  • 34
  • 34
  • 33
  • 33
  • 32
  • 31
  • 29
  • 27
  • 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.
161

Desenvolvimento da metodologia para realizar a qualificação de performance do biorreator utilizado para produção de toxina diftérica. / Development of the bioreactor performance qualification methodology to be use in the diphtheria toxin production.

Ferreira, Adriano Alves 08 November 2013 (has links)
A Qualificação de Performance (QP) é requisito das Boas Práticas de Fabricação e consiste de uma documentação de todas as atividades envolvidas para produzir um produto específico, neste caso, a toxina diftérica. O objetivo é garantir que as especificações do produto atendam aos resultados das análises de rotina. O Instituto Butantan introduziu um biorreator para ser utilizado nesta produção e a QP foi considerada e desenvolvida. Análises da temperatura e pressão foram realizadas durante três ciclos de esterilização. Sensores de temperatura e indicadores biológicos foram previamente distribuídos no equipamento considerando pontos críticos pré-observados. Os resultados da curva de temperatura e pressão validaram o equipamento. Três ciclos de crescimento de C. diphtheriae foram realizados e monitorados. Os resultados da DO ou turbidez medidos tanto por um espectrofotometro convencional como por um sensor de biomassa on line mostraram títulos da toxina já a partir de 48 horas (teste de floculação). A toxina foi caracterizada bioquimicamente. / Performance qualification (PQ) is requisite of the Good Manufacturing Practices and consists on complete documentation of all activities involved to produce a specific product, in this case, the diphtheria toxin. The goal is to ascertain all product specifications that were determined by its routine analysis. Instituto Butantan introduced a bioreactor to be use in the diphtheria toxin production and the PQ must be considered and developed. Analysis of the temperature and the pressure were performed during three sterilization cycles. Temperature sensors and biological indicators where previously distributed in the equipment, considering critical pre-observed points. The temperature and pressure curve results validated the equipment. Three C. diphtheriae growth cycles were performed and monitored. The optical density (OD) or turbidity results measured either by one conventional spectrophotometer and/or by one on line biomass sensor showed toxin titers after 48 hours of the harvesting (flocculation test). The toxin was biochemically characterized.
162

Sequenciamento do genoma da serpente Bothrops jararaca para caracterização da estrutura gênica de toxinas. / Genome sequencing of Bothrops jararaca snake for toxin gene structure characterization.

Almeida, Diego Dantas 07 December 2016 (has links)
A Bothrops jararaca é a serpente de maior importância médica no Brasil. Vários estudos foram realizados com o objetivo de caracterizar os componentes do veneno de serpentes, entretanto, a base molecular dos genomas das serpentes é pouco conhecida. Assim, foi realizado o sequenciamento e montagem do genoma da serpente Bothrops jararaca. Foram construídas bibliotecas tipo shotgun e mate-pair para realização de corridas de sequenciamento usando a tecnologia Illumina e sequências complementares foram obtidas em equipamento PACBIO RS II. Uma biblioteca de BACs também foi construída e 768 pools de 12 BACs foram sequenciados. Um grande conjunto de segmentos genômicos foi obtido e foi possível identificar genes de várias toxinas, entre elas SVMPs, SVSPs, BPPs, CRISPs e VEGF. Ainda foi possível depreender o contexto genômico de muitos destes genes e identificamos os principais elementos repetitivos genômicos. Estes achados são relevantes para o entendimento da função e evolução do sistema venenífero e podem servir de base para outros estudos futuramente. / The pit viper Bothrops jararaca is the most medically important snake in Brazil. Several studies were conducted in order to characterize the components of snake venom. However, the molecular basis of snake genomes is poorly known. Hence, it was carried out the sequencing and assembly of the Bothrops jararaca snake genome. Shotgun and mate-pair libraries were constructed to perform sequencing runs using Illumina technology and complementary sequences were obtained in PACBIO RS II equipment. A BAC library was also constructed and 768 pools of 12 BACs were sequenced. A large number of genomic segments was obtained. It was possible to identify genes of several toxins, including SVMPs, SVSPs, BPPs, CRISPs and VEGF. In addition, it was possible to infer the genomic context related to most of these genes and identify the main genomic repetitive elements. These findings are relevant for understanding the function and evolution of the venom system and it provides the basis for further studies.
163

Influência da ativação ultrassônica do gel de hipoclorito de sódio 3 por cento, e da medicação intracanal com hidróxido de cálcio sobre micro-organismos e ácido lipoteicóico /

Pelegrini, Fernanda Carvalho. January 2017 (has links)
Orientador: Claudio Antônio Talge Carvalho / Banca: Márcia Carneiro Valera Garakis / Banca: Renato Miotto Palo / Resumo: O objetivo deste estudo foi avaliar in vitro a ação do gel de hipoclorito de sódio (NaOCl) 3 % e da medicação intracanal (MIC) de hidróxido de cálcio (CaOH2), agitados ou não por ultrassom sobre Enterococcus faecalis, Escherichia coli e ácido lipoteicóico (LTA). Para isso 80 dentes humanos unirradiculares tiveram suas coroas removidas padronizando seu comprimento em 16 mm +- 0,5 mm, sendo seus canais instrumentados inicialmente até instrumento R25 (Reciproc). Os canais foram contaminados com suspensões de E. faecalis e E. coli. Os canais foram instrumentados utilizando-se instrumento R40, sob irrigação com 2 ml de NaOCl 3% gel seguida de irrigação com 10 ml de solução salina estéril e apirogênica. Após os canais foram irrigados com EDTA 17%, seguido de irrigação com 5 ml de solução salina estéril e apirogênica, sendo por último preenchidos com medicação intracanal de hidróxido de cálcio mantida durante 7 ou 14 dias. Os espécimes foram divididos inicialmente em 2 grupos (n=40) de acordo com a agitação ultrassônica (US) ou não da substância química auxiliar. Sendo novamente divididos de acordo com a agitação ultrassônica ou não da medicação intracanal (MIC) e o tempo de ação desta (n=10): 1) NaOCl + Ca(OH)2 (7 dias). 2) NaOCl + Ca(OH)2 (14 dias). 3) NaOCl + Ca(OH)2 com US (7 dias) 4) NaOCl + Ca(OH)2 com US (14 dias). 5) NaOCl com US + Ca(OH)2 (7 dias). 6) NaOCl com US + Ca(OH)2 (14dias) 7) NaOCl com US + Ca(OH)2 com US (7dias). 8) NaOCl com US + Ca(OH)2 com US (14 dias). For... (Resumo completo, clicar acesso eletrônico abaixo) / The aim of this study was to evaluate in vitro the action of sodium hypochlorite (NaOCl) 3% gel and calcium hydroxide as an intracanal medication, both activated by ultrasound on the reduction of E. faecalis e E. coli and lipotheicoic acid (LTA). Eight human single-rooted teeth with standardized size of 16 mm were prepared initially to R25 instrument (Reciproc) and distributed in microplate (n = 10). After sterilization (Co60 gamma radiation), the infection was carried out 8 microlitres of E. coli suspension, and after 7 days 8 microlitres of E. faecalis suspension, maintained for 21 days. Following the collection confirmation was performed (1st collection), then the root were instrumented using R40 instrument, irrigation with 2 ml of NaOCl 3% gel followed by washing with 10 ml of saline. The specimens were divided into 8 groups (n = 10) according to different ultrasonic irrigation protocols and different periods exposed to intracanal medication: 1) NaOCl + Ca(OH)2(7 days). 2) NaOCl + Ca(OH)2 (14 days). 3) NaOCl + Ca(OH)2 with PUI (7 dias) 4) NaOCl + Ca(OH)2 with PUI (14 days). 5) NaOCl with PUI + Ca(OH)2 (7 days). 6) NaOCl with PUI + Ca(OH)2 (14 days) 7) NaOCl with PUI + Ca(OH)2 (7 days). 8) NaOCl with PUI + Ca(OH)2 with PUI (14 days). Were made to sample colections of content of root canals, after instrumentation (2nd sample), after the use of EDTA (3rd sample) and after the Ca(OH)2 (4th Collection) . Microbiological culture and LTA quantification revealed that 3 % NaOCl gel was capable to eliminate E. faecalis and E. coli almost completely from root canals, but not lipotheicoic acid, regardless the use of ultrasonic activation. The ultrasonic activation of intracanal medication (Ca(OH)2) was not effective in removing neither microorganisms nor LTA. In addition, the groups with greatest reduction were the ones with no ultrasonic activation either of intracanal.... (Resumo completo, clicar acesso eletrônico abaixo) / Mestre
164

Ação do hipoclorito de sódio 2,5 por cento e medicação intracanal com agitação ultrassônica sobre microorganismos e ácido lipoteicóico em canais radiculares /

Ferreira, Cláudia Luísa Ribeiro. January 2017 (has links)
Orientador: Cláudio Antonio Talge Carvalho / Banca: Frederico Canato Martinho / Banca: Renata Amadei Nicolau / Resumo: O objetivo deste estudo foi analisar a eficácia do hipoclorito de sódio (NaOCl) 2,5 por cento e medicação intra-canal (MIC) com hidróxido de cálcio (Ca(OH)2) agitados com ultrassom ou não, sobre, Escherichia coli, Enterococcus faecalis e àcido lipoteicóico (LTA). Foram utilizados 80 dentes unirradiculares que foram instrumentados usando lima R40 do sistema Reciproc irrigados com 40 mL de NaOCl. Em seguida, os dentes foram aleatoriamente distribuídos em 8 grupos, de acordo com o protocolo de limpeza final e MIC: G1- agitação ultrassônica do NaOCl e MIC 7 dias, G2- agitação ultrassônica do NaOCl e MIC 14 dias, G3- agitação ultrassônica do NaOCl e sem agitação da MIC 7 dias, G4- agitação ultrassônica do NaOCl e sem agitação da MIC 14 dias, G5- sem agitação ultrassônica do NaOCl e com agitação da MIC 7 dias, G6- sem agitação ultrassônica do NaOCl e com agitação da MIC 14 dias, G7- sem agitação ultrassônica do NaOCl e MIC 7 dias e G8- sem agitação ultrassônica do NaOCl e MIC 14 dias. Foi feita a contagem de Unidades Formadoras de Colônias por mililitro (UFC/mL) e quantificação de LTA. Todos os dados foram analisados estatisticamente. Os resultados mostraram uma diminuição de micro-organismos imediatamente após o PBM (preparo biomecânico) (p<0,001). Nenhum protocolo empregado foi eficiente na completa eliminação de LTA. Pode-se concluir que em todos os grupos após o PBM houve redução/eliminação dos MO (micro-organismos), mas nenhum método testado foi eficiente par... (Resumo completo, clicar acesso eletrônico abaixo) / The purpose of this study was to evaluate the efficacy of 2.5% sodium hypochlorite (NaOCl) and intracanal medications using calcium hydroxide (Ca(OH)2) associated with ultrasound on Escherichia coli, Enterococcus faecalis and lipoteichoic acid (LTA). 80 single-rooted teeth were used that were instrumented using R40 file from the Reciproc system irrigated with 40 mL of NaOCl. Then, the teeth were randomly divided in 8 groups, according to the final cleansing protocol and intracanal medication period: G1- Ultrasonic activation of both NaOCl and Ca(OH)2 (7 days); G2 - Ultrasonic activation of NaOCl and Ca(OH)2 (14 days); G3 - Ultrasonic activation of NaOCl and no activation of Ca(OH)2 (7 days); G4- Ultrasonic activation of NaOCl and no activation of Ca(OH)2 (14 days); G5- no ultrasonic activation of NaOCl and ultrasonic activation of Ca(OH)2 (7 days); G6- no ultrasonic agitation of NaOCl and ultrasonic agitation of Ca(OH)2 (14 days); G7- no ultrasonic activation of NaOCl and Ca(OH)2(7 days) and G8- no ultrasonic activation of either NaOCl and Ca(OH)2(14 days).Culture techniques determined the colony-forming units (CFU) and the LTA was quantified. Data obtained was analyzed statistically. The results showed a decrease in microorganisms immediately after biomechanical preparation (p <0.001). After biomechanical preparation a reduction/elimination of microoganisms was detected in all groups, however All groups after PBM there was reduction / elimination of MO, but none of the protocols ...(Resumo completo, clicar acesso eletrônico abaixo) / Mestre
165

Investigation of the mechanisms involved in cylindrospermopsin toxicity : hepatocyte culture and reticulocyte lysate studies

Froscio, Suzanne M. January 2002 (has links) (PDF)
Bibliography: leaves 121-139. The aim of this study was to determine the extent to which protein synthesis inhibition, lowered glutathione (GSH) levels and toxin metabolism contribute to the toxicity of cyclindrospermopsin. Both hepatocyte cultures and reticulocyte lysates were utilized as in vitro tools of investigation. The findings imply that the inhibition of protein synthesis by direct action of the toxin cannot be considered a primary cause of hepatocyte cell death over an acute time frame. Cytochrome P450-derived metabolites may play a crucial role in cytotoxicity, and the toxicity process does not appear to involve oxidative damage.
166

Toxicology Investigations With The Pectenotoxin-2 Seco Acids

Burgess, Vanessa Anne, n/a January 2003 (has links)
Pectenotoxins (PTXs) are a group of large cyclic polyether compounds associated with diarrhetic shellfish poisoning (DSP) as they are often found in combination with other DSPs such as okadaic acid (OA) and dinophysis toxins (DTXs) in shellfish. Although classified and regulated with the DSPs, there is debate over whether these toxins should be classified with DSP toxins. To date, ten different analogues of PTXs have been identified from shellfish and algae, and of these, the pectenotoxin-2 seco acids (PTX2-SAs) are of particular interest as they have previously been implicated in a shellfish poisoning incident in Australia, but relatively little was known of their toxicology. One such incident occurred in December 1997, when approximately 200 people were reported with severe diarrhoetic shellfish poisoning in Northern New South Wales (NSW). Analysis of the shellfish associated with this incident revealed relatively high PTX2-SA concentrations (approx. 300 micrograms/kg shellfish meat), with only trace amounts of pectenotoxin-2 (PTX2) and OA. Following this incident, PTX2-SAs were considered a health threat and guidelines were implemented in the absence of toxicological data, which has caused a great economic burden to shellfish industries around the globe, in particular to Australia, New Zealand and Ireland. Such regulation created in the absence of scientific data demonstrated the need to determine the toxicology of PTX2-SAs in commercial shellfish. Thus a comprehensive study on the toxicology and possible health implications of the PTX2-SAs in Australian shellfish was conducted. PTX2-SAs were isolated in different batches from shellfish (pipis, oysters and mussels) and from algal bloom samples of Dinophysis caudata. Toxin extraction was conducted with several purification stages and chemical analysis was performed with high-performance liquid chromatography coupled to a tandem mass spectrometer (HPLC-MS/MS). The chemical stability of the PTX2-SAs was investigated to ensure consistency of doses between toxicology experiments. Acute dosing studies with mice were then performed and included toxicopathology investigations with light microscopy and electron microscopy, in addition to toxin distribution studies and investigation of in vivo lipid peroxidation. In vitro studies with HepG2 cells included cytotoxicity assays, cell cycle investigations using flow cytometry and gene expression profiling of cells exposed to PTX2-SAs employing cDNA microarray technology. Acute pathology studies demonstrated that the PTX2-SAs do not cause the characteristic symptoms or lesions associated with DSP toxins. No diarrhoea was observed at any dose level in mice and no deaths occurred up to the maximum dosing level of 1.6mg/kg PTX2-SA. Only one batch of PTX2-SA extract produced toxic lesions characteristic of a DSP toxin (batch 1-pilot study) but after follow up studies, it was determined that this first batch of shellfish most likely contained an additional unidentified shellfish toxin or contaminant that co-extracted with PTX2-SAs during toxin isolation and purification procedures. This finding highlighted the importance of supporting the inclusion of the mice bioassay in procedures for shellfish toxin testing to enable detection of new toxins, and also highlighted the importance of toxin purification for toxicology studies. A significant rise in malondialdehyde excretion was observed within 24 hours of dosing mice, indicating that the PTX2-SAs may cause damage by lipid peroxidation in vivo. In vitro studies showed HepG2 cells to have cell cycle and gene expression changes within 24 hours of a dose of 800ng/mL PTX2-SAs. Cell cycle arrest was observed at the G2/M checkpoint and gene expression changes included alterations in genes involved in cell cycle control, lipid metabolism and transport, lipid genesis and trace metal transport. Many genes involved in DNA repair processes were moderated at the 24 hour point, but as no apoptosis was observed up to 72 hours post dosing it is a promising indication that any DNA damage that may have been caused by the administration of PTX2-SAs was not lethal, and was able to be repaired. In light of the information provided by toxicology investigations in this PhD, with particular reference to evidence of in vivo lipid peroxidation by raised levels of MDA in mouse urine, and changes in cell cycle distribution and gene expression in a cultured human cell line, it is concluded that there is potential for these toxins to induce biological changes in mammalian cells in vivo and in vitro, and hence potential for PTX2-SAs to cause health effects in humans. During the course of this three-year study, developments in techniques for shellfish toxin identification within our laboratories have revealed that the shellfish responsible for the 1997 NSW poisoning incident contained significant concentrations of okadaic acid acyl esters that were not detected at the time of the NSW incident. Although reportedly less toxic than okadaic acid itself, the OA ester concentrations present may have been sufficient to cause the observed symptoms. It is also theorized that these esters could be hydrolyzed in the human gastro-intestinal tract to release okadaic acid. In the light of this new evidence and with no pathology lesions or symptoms of diarrhoea being observed in PTX2-SA dosing studies with mice, we now believe these OA acyl esters to be the causative agent in the 1997 NSW DSP incident and not the PTX2-SAs. Nothing is currently known of the chronic toxicology of PTX2-SAs and thus their potential implications to public health in the long term cannot determined. The toxicology investigations in this thesis were acute studies, and it has not been established if the observed changes could be repaired or returned within normal limits without the manifestation of illness or disease occurring. Utilizing the acute toxicology information in this thesis, a health risk assessment for consumption of PTX2-SA contaminated shellfish was performed. This risk assessment, employing numerous safety factors essential for an incomplete data set, produced guideline values that are lower than the current recommend concentrations. To date, there has been no solid evidence that PTX2-SAs cause illness in humans – all documented incidents involving the PTX2-SAs have also included other DSP contaminants that are known to cause human illness. Pathology has not unequivocally been demonstrated in animal studies and thus, in consideration of the epidemiological evidence, PTX2-SAs cannot be considered as high a risk to public health as was previously thought. For the reasons discussed above, and weighing up risk-benefit considerations of the economic burden the current guideline values are causing to shellfish industries around the globe, it is recommended that levels of PTX2-SAs be monitored in recognition of the precautionary principle, but no longer regulated as tightly with other DSPs until such a time that toxicological or epidemiological evidence can prove that the PTX2-SAs are a DSP and are a more considerable threat to human health than has been indicated by toxicology studies in this thesis. This study has produced a substantial amount of acute toxicology data and has provided a good basis for future chronic toxicology investigations with the PTX2-SAs for regulatory purposes.
167

Effects of bacterial toxins on the proliferation, osteogenic differentiation and toll-like receptor expressions of human mesenchymal stromal cells /

Mo, Fung-ying, Irene. January 2006 (has links)
Thesis (M. Phil.)--University of Hong Kong, 2007. / Also available online.
168

Effects of bacterial toxins on the proliferation, osteogenic differentiation and toll-like receptor expressions of human mesenchymal stromal cells

Mo, Fung-ying, Irene. January 2006 (has links)
Thesis (M. Phil.)--University of Hong Kong, 2007. / Title proper from title frame. Also available in printed format.
169

Synthesis of marine natural products. part I, Cryptophycins-1, -3, -4, -24, and -29, part II, Polycavernoside A

Robarge, Lonnie A. 01 February 2001 (has links)
Graduation date: 2001
170

Role of Ca2+ -permeable cation channels in Ca2+ Signalling and necrotic cell death

Wisnoskey, Brian J. January 2004 (has links)
Thesis (Ph. D.)--Case Western Reserve University, 2004. / [School of Medicine] Department of Physiology and Biophysics. Includes bibliographical references. Available online via OhioLINK's ETD Center.

Page generated in 0.0443 seconds