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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.
241

Obtenção e avaliação da atividade de compostos isolados de Piper em modelos biológicos para o controle da esquistossomose mansônica. / Obtention an evaluation of Piper compounds in biological models to schistosomiasis mansoni control.

Rapado, Ludmila Nakamura 10 August 2012 (has links)
A esquistossomose é incidente em países tropicais e subtropicais e o uso de moluscicidas é adequado para prevenir a infecção de pessoas. O objetivo deste estudo foi buscar compostos em Piper ativos em Biomphalaria glabrata e avaliar a atividade esquistossomicida e toxicidade do composto mais ativo. O fracionamento biomonitorado de Piper diospyrifolium resultou no isolamento da flavocavaína A e ácido 4-hidroxi-3-[3,7,11-trimetildodeca-2,6,10-trienil]benzoico. A busca de compostos também foi realizada em amidas e chalconas e dos oito compostos avaliados, quatro foram ativos, sendo a piplartina mais ativa. A piplartina não foi letal a miracídios e cercárias de Schistosoma mansoni e foi tóxica em Daphnia similis e Danio rerio, contudo ainda foi menos tóxica que a niclosamida. Neste estudo, os compostos moluscicidas foram obtidos pelo fracionamento biomonitorado de P. diospyrifolium e pela avaliação da atividade de amidas e chalconas. Ambas as metodologias foram adequadas e a análise de componente principal mostrou ser uma ferramenta viável para a busca de compostos. / Schistosomiasis is a parasitic disease and the use of molluscicides has been considered an appropriate method to prevent human infection. The aim of this study was to search for compounds in Piper active in B. glabrata and evaluate schistosomicidal activity and toxicity of the most active compound. The P. diospyrifolium bioguided fractionation resulted in flavokavain A and 4-hydroxy-3-[3,7,trimetildodeca-11-2,6,10-trienil]benzoic acid isolation. The search for active compounds was carried out in amides and chalcones. Eight compounds were evaluated, four were active and piplartine was the most active. There was no mortality of miracidia and cercariae exposed to piplartine. It was classified as toxic to D. similis and D. rerio; nevertheless was less toxic than niclosamide. In this study, molluscicidal compounds were obtained from bioguided fractionation of P.diospyrifolium and by evaluating the activity of amides and chalcones. Both methods were suitable to obtain active compounds and principal component analysis also proved to be a viable tool for obtain compounds.
242

Physico-chemical characteristics and quantitative structure-activity relationships of PCBs

Andersson, Patrik January 2000 (has links)
<p>The polychlorinated biphenyls (PCBs) comprise a group of 209 congeners varying in the number of chlorine atoms and substitution patterns. These compounds tend to be biomagnified in foodwebs and have been shown to induce an array of effects in exposed organisms. The structural characteristics of the PCBs influence their potency as well as mechanism of action. In order to assess the biological potency of these compounds a multi-step quantitative structure-activity relationship (QSAR) procedure was used in the project described in this thesis.</p><p>The ultraviolet absorption (UV) spectra were measured for all 209 PCBs, and digitised for use as physico-chemical descriptors. Interpretations of the spectra using principal component analysis (PCA) showed the number of ortho chlorine atoms and para-para substitution patterns to be significant. Additional physico-chemical descriptors were derived from semi-empirical calculations. These included various molecular energies, the ionisation potential, electron affinity, dipole moments, and the internal barrier of rotation. The internal barrier of rotation was especially useful for describing the conformation of the PCBs on a continuous scale.</p><p>In total 52 physico-chemical descriptors were compiled and analysed by PCA for the tetra- to hepta-chlorinated congeners. The structural variation within these compounds was condensed into four principal properties derived from a PCA for use as design variables in a statistical design to select congeners representative for these homologue-groups. The 20 selected PCBs have been applied to study structure-specific biochemical responses in a number of bioassays, and to study the biomagnification of the PCBs in various fish species.</p><p>QSARs were established using partial least squares projections to latent structures (PLS) for the PCBs potency to inhibit intercellular communication, activate respiratory burst, inhibit dopamine uptake in synaptic vesicles, compete with estradiol for binding to estrogen receptors, and induce cytochrome P4501A (CYP1A) related activities. By the systematic use of the designed set of PCBs the biological potency was screened over the chemical domain of the class of compounds. Further, sub-regions of highly potent PCBs were identified for each response measured. For risk assessment of the PCBs potency to induce dioxin-like activities the predicted induction potencies (PIPs) were calculated. In addition, two sets of PCBs were presented that specifically represent congeners of environmental relevance in combination with predicted potency to induce estrogenic and CYP1A related activities.</p>
243

Physico-chemical characteristics and quantitative structure-activity relationships of PCBs

Andersson, Patrik January 2000 (has links)
The polychlorinated biphenyls (PCBs) comprise a group of 209 congeners varying in the number of chlorine atoms and substitution patterns. These compounds tend to be biomagnified in foodwebs and have been shown to induce an array of effects in exposed organisms. The structural characteristics of the PCBs influence their potency as well as mechanism of action. In order to assess the biological potency of these compounds a multi-step quantitative structure-activity relationship (QSAR) procedure was used in the project described in this thesis. The ultraviolet absorption (UV) spectra were measured for all 209 PCBs, and digitised for use as physico-chemical descriptors. Interpretations of the spectra using principal component analysis (PCA) showed the number of ortho chlorine atoms and para-para substitution patterns to be significant. Additional physico-chemical descriptors were derived from semi-empirical calculations. These included various molecular energies, the ionisation potential, electron affinity, dipole moments, and the internal barrier of rotation. The internal barrier of rotation was especially useful for describing the conformation of the PCBs on a continuous scale. In total 52 physico-chemical descriptors were compiled and analysed by PCA for the tetra- to hepta-chlorinated congeners. The structural variation within these compounds was condensed into four principal properties derived from a PCA for use as design variables in a statistical design to select congeners representative for these homologue-groups. The 20 selected PCBs have been applied to study structure-specific biochemical responses in a number of bioassays, and to study the biomagnification of the PCBs in various fish species. QSARs were established using partial least squares projections to latent structures (PLS) for the PCBs potency to inhibit intercellular communication, activate respiratory burst, inhibit dopamine uptake in synaptic vesicles, compete with estradiol for binding to estrogen receptors, and induce cytochrome P4501A (CYP1A) related activities. By the systematic use of the designed set of PCBs the biological potency was screened over the chemical domain of the class of compounds. Further, sub-regions of highly potent PCBs were identified for each response measured. For risk assessment of the PCBs potency to induce dioxin-like activities the predicted induction potencies (PIPs) were calculated. In addition, two sets of PCBs were presented that specifically represent congeners of environmental relevance in combination with predicted potency to induce estrogenic and CYP1A related activities.
244

Characterization of PAH-contaminated soils focusing on availability, chemical composition and biological effects

Bergknut, Magnus January 2006 (has links)
The risks associated with a soil contaminated by polycyclic aromatic hydrocarbons (PAHs) are generally assessed by measuring individual PAHs in the soil and correlating the obtained amounts to known adverse biological effects of the PAHs. The validity of such a risk estimation is dependent on the presence of additional compounds, the availability of the compounds (including the PAHs), and the methods used to correlate the measured chemical data and biological effects. In the work underlying this thesis the availability, chemical composition and biological effects of PAHs in samples of soils from PAH-contaminated environments were examined. It can be concluded from the results presented in the included papers that the PAHs in the studied soils from industrial sites were not generally physically trapped in soil material, indicating that the availability of the PAHs was not restricted in this sense. However, the bioavailable fraction of the PAHs, as assessed by bioassays with the earthworm Eisenia Fetida, could not be assessed by a number of abiotic techniques (including: solid phase micro extraction, SPME; use of semi-permeable membrane devices, SPMDs; leaching with various solvent mixtures, leaching using additives, and sequential leaching) and it seems to be difficult to find a chemical method that can accurately assess the bioavailability of PAHs. Furthermore, it was shown that PAH-polluted samples may be extensively chemically characterized by GC-TOFMS using peak deconvolution, and over 900 components can be resolved in a single run. The chemical characterization also revealed that samples that appeared to be similar in terms of their PAH composition were heterogeneous in terms of their overall composition. Finally, single compounds from this large set of compounds, which correlated with different biological effects, could be identified using the multivariate technique partial least squares projections to latent structures (PLS). This indicates that PLS may provide a valid alternative to Effect Directed Analysis (EDA), an established method for finding single compounds that correlate to the toxicity of environmental samples. Thus, the instrumentation and data evaluation tools used in this thesis are clearly capable of providing a broad chemical characterization as well as linking the obtained chemical data to results from bioassays. However, the link between the chemical analyses and the biological tests could be improved as as an organic solvent that solubilised virtually all of the contaminants was used during the chemical analysis while the biological tests were performed in an aqueous solution with limited solubility for a number of compounds. Consequently the compounds probably have a different impact in the biological tests than their relative abundance in profiles obtained by standard chemical analyses suggests. The availability and bioavailability of contaminants in soil also has to be studied further, and such future studies should focus on the molecular interactions between the contaminants and different compartments of the soil. By doing so, detailed knowledge could be obtained which could be applied to a number of different contaminants and soil types. Such studies would generate the data needed for molecular-based modelling of availability and bioavailability, which would be a big step forward compared to current risk assessment practices.
245

Optimal Designs for Calibrations in Multivariate Regression Models

Lin, Chun-Sui 10 July 2006 (has links)
In this dissertation we first consider a parallel linear model with correlated dual responses on a symmetric compact design region and construct locally optimal designs for estimating the location-shift parameter. These locally optimal designs are variant under linear transformation of the design space and depend on the correlation between the dual responses in an interesting and sensitive way. Subsequently, minimax and maximin efficient designs for estimating the location-shift parameter are derived. A comparison of the behavior of efficiencies between the minimax and maximin efficient designs relative to locally optimal designs is also provided. Both minimax or maximin efficient designs have advantage in terms of estimating efficiencies in different situations. Thirdly, we consider a linear regression model with a one-dimensional control variable x and an m-dimensional response variable y=(y_1,...,y_m). The components of y are correlated with a known covariance matrix. The calibration problem discussed here is based on the assumed regression model. It is of interest to obtain a suitable estimation of the corresponding x for a given target T=(T_1,...,T_m) on the expected responses. Due to the fact that there is more than one target value to be achieved in the multiresponse case, the m expected responses may meet their target values at different respective control values. Consideration includes the deviation of the expected response E(y_i) from its corresponding target value T_i for each component and the optimal value of calibration point x, say x_0, is considered to be the one which minimizes the weighted sum of squares of such deviations within the range of x. The objective of this study is to find a locally optimal design for estimating x_0, which minimizes the mean square error of the difference between x_0 and its estimator. It shows the optimality criterion is approximately equivalent to a c-criterion under certain conditions and explicit solutions with dual responses under linear and quadratic polynomial regressions are obtained.
246

Reaktive Toxizität in vitro

Laqua, Anja 07 February 2014 (has links) (PDF)
Es wird eine Bioassay-Analyse von 168 Testsubstanzen gegenüber Tetrahymena pyriformis beschrieben. Mithilfe dieses In-vitro-Ansatzes konnte eine erste prognostische Aussage über die toxische Wirkung unbekannter Stoffe getroffen werden. Aus den Konzentrations-Wirkungs-Beziehungen erfolgte eine Bestimmung der Toxizitätserhöhung gegenüber der Narkoselevel-Toxizität. Dadurch war eine mechanistische Interpretation der Wirkstärke der Fremdstoffe möglich. Die Wirkung der Fremdstoffe basiert auf direkten toxikologisch relevanten Reaktionsmechanismen mit nukleophilen Biomolekülen oder nach entsprechender enzymatischer Aktivierung und ermöglichte die Aufstellung von Strukturalarmen. Aus jeder Stoffklasse waren Vertreter direkt oder nach enzymatischer Biotransformation erhöht toxisch. Somit ist mithilfe der Ciliaten eine Vorhersage der direkten reaktiven Toxizität möglich. Zudem enthält es für eine metabolische Aktivierung bedeutsame Enzymsysteme. Damit ist es für eine prognostische Vorhersage der Toxizität unbekannter Stoffe anwendbar.
247

Physical and chemical limnological study of an acid mine lake in Sullivan County, Indiana

Broomall, Phillip A. January 1992 (has links)
Southwestern Indiana has numerous lakes developed in abandoned coal mine spoils which support recreational sports fisheries. Some lakes, due to exposure to acid mine drainage from coal wastes and pyritic spoils, are unsuitable habitats for fisheries development. This study examines a publicly owned acid mine lake with an area of approximately 51 ha, following reclamation and elimination of acid producing areas in its drainage basin. Fifteen physico-chemical sample collections were made over a thirteen month period (1991-1992). Parameters sampled included pH, total acidity, iron, manganese, and aluminum. Comparisons were made to historic pre-reclamation water quality data and to established models of acid mine lake recovery. Due to the local topography and exposure to prevailing winds, the lake was generally well mixed throughout the study. Virtually no summer stratification was found, but typical winter season stratification occurred. The water column was well oxygenated throughout the study. Secchi disk transparency varied from 2.5 m to clear to lake bottom (6 m). This study found no significant change in lake water pH (2.9-3.0 to 3.0-3.2 s.u.) since reclamation activities in 1988. However, changes in total acidity and total metal concentrations had occurred since reclamation which suggested that the lake was in early recovery stages. No trends in water quality improvement were determined which could assist in planning toward the eventual establishment of a sports fishery. / Department of Biology
248

Productivity Analyses In Fermentations With Three Different Biolarvacides

Ozcelik, Hayriye 01 April 2004 (has links) (PDF)
The development of insecticides resistance among many insect species and the ecological damage occasionally caused by the lack of specificity in the toxic effects of insecticides have provided the impetus to seek alternative methods of insect control. This observation led to the development of bioinsecticides based on the insecticidal action Bacillus sphaericus (Bs), Bacillus turingiensis (Bt). The discovery of biolarvicidal actions of Bacillus thuringiensis and Bacillus sphaericus opened a new perspective for insect control. In the first part of the study was initiated to determine a suitable fermentation medium formulation and optimal fermentation conditions for large scale, low cost production of Bs. Bs 2362 was tested in whey and soy flour based media. These media was reformulized form of NYSM (Nutrient Broth Yeast Extract Sporulation Medium). Soy flour based medium, SYSM, gave the promising results in terms of cell yield, sporulation frequency and toxin production. In the second part of the study, fermentation productivity anlaysis of a local isolate Bacillus thuringiensis subsp. kurstaki 81 was evaluated. In order to compare different C:N ratios (1:1, 2:1, 4:1, 8:1, 10:1 20:1 and 30:1) of YSM medium. Btk 81 were run for 72 h and cell growth, sporulation and toxin protein profile of Btk 81 were determined for each. When all the quantitative toxin data for both glucose and sucrose varying C:N ratios were compared, it was determined that the crystal protein concentrations had the highest value in sucrose based medium when C:N ratio was 10:1. Regulation by C:N ratio of crystal protein biosynthesis was investigated for improving the production of this protein by our third candidate strain Bacillus thuringiensis subsp. israelensis ONR60. The experiments were performed by using TBL medium, at three different C:N ratios, 2:1, 4:1 and 8:1 respectively. In view of the cell growth characteristics and bioassy results, TBL medium designed with 2:1 C:N ratio was chosen as the best for further steps. In addition, running time of the culture determined as 60 hours as was also determined in the previous experiment. As the last step of this study, the pre-determined optimal conditions were applied to a 30L batch type fermentor for toxin production by using Bacillus thuringiensis subsp. israelensis ONR60. Unfortunately, the toxicity was not satisfactory, being much below the level of that expected as based on the results of the laboratory scale studies.
249

Estrogenic and androgenic potential of municipal sewage in Australia and New Zealand

Leusch, F. D. L. January 2004 (has links)
Studies in Europe, Japan, and North America have reported that wild fish exposed to treated sewage effluents can exhibit significant physiological and reproductive abnormalities consistent with exposure to hormonally active chemicals. The main objective of this research project was to examine the estrogenic and androgenic activity in treated sewage to determine the risk associated with treated sewage discharges in Australia and New Zealand. Several bioassays, including a sheep estrogen receptor and a rainbow trout androgen receptor binding assay, were set up and validated with model compounds. The assays were then used to measure the estrogenic and androgenic activity in sewage samples from 15 municipal sewage treatment plants (STP) utilizing a variety of treatment technologies. Raw sewage samples contained high levels of both estrogenic and androgenic activity, up to 185 ng/L estradiol equivalents (EEq) and up to 9330 ng/L testosterone equivalents (TEq), respectively. Secondary treatment processes such as activated sludge had the greatest impact on removal of biological activity from the wastewater. The estrogenic and androgenic activity in final treated effluents were <1 to 4.2 ng/L EEq and <6.5 to 736 ng/L TEq, respectively. Based on lowest observable effective concentrations reported in the literature, these levels are unlikely to induce biological effects in exposed fish in the short term. To examine potential long-term effects, resident mosquitofish chronically exposed to undiluted treated sewage were sampled. Several morphological biomarkers indicative of endocrine disruption were measured and compared with mosquitofish captured at a reference site. Mosquitofish captured in a constructed wetland for tertiary treatment of secondary treated sewage exhibited morphological differences such as elongated anal fins consistent with exposure to androgenic chemicals, although this effect was not measurable in fish collected at sites further downstream or at any of the other sites. Based on these results, it is unlikely that mosquitofish populations would be significantly affected by exposure to final treated sewage. A reverse transcription real-time polymerase chain reaction (RT-PCR) method to measure the production of a female-specific protein (vitellogenin) mRNA in adult male mosquitofish was developed, and this could be used as a rapid test to detect early changes in individuals exposed to estrogenic activity.
250

DESENVOLVIMENTO E VALIDAÇÃO DE MÉTODO CROMATOGRÁFICO PARA AVALIAÇÃO DE POTÊNCIA DE ERITROPOIETINA HUMANA RECOMBINANTE. CORRELAÇÃO COM O ENSAIO BIOLÓGICO / DEVELOPMENT AND VALIDATION OF CHROMATOGRAPHIC METHOD FOR THE POTENCY ASSESSMENT OF RECOMBINANT HUMAN ERYTHROPOIETIN. CORRELATION WITH THE BIOLOGICAL ASSAY

Barth, Thiago 10 April 2007 (has links)
Erythropoietin is a glycoprotein which stimulates the erythropoiesis, clinically used for the treatment of renal anaemia. The biological and chromatographic methods for the potency evaluation of recombinant human erythropoietin (rhEPO) in pharmaceutical products were validated in the present work. The normocythaemic mice bioassay was carried out in female BALB/c strain, with multiple injections schedule and reticulocytes counted by automated flow cytometry. The dose-response curve was linear (r2=0.9708) in the concentration range of 1 to 64 IU/mL. A reversed-phase liquid chromatography method (RP-LC) was developed and validated using a Jupiter C4 column (250 mm x 4.6 mm), maintained at ambient temperature (25°C). The mobile phase A consisted of 0.1% trifluoroacetic acid (TFA) and mobile phase B consisted of 0.08% TFA:acetonitrile (30:70, v/v), run in linear gradient: 0.1-60 min, 0.1-100% of B at flow rate of 0.5 mL/min with detection at 280 nm. The chromatographic separation was obtained within 60 min and it was linear (r2=0.9997) in the concentration range of 10-150 μg/mL. The procedures were validated evaluating parameters such as, the specificity, linearity, precision, accuracy, robustness, and limit of quantitation, as well as, the limit of detection evaluated in the validation of the chromatographic method. The methods were applied for the potency evaluation of the alfa and beta rhEPO in pharmaceutical products, which were analysed by the chromatographic method and compared to the bioassay showing mean differences between the estimated potencies of 11.2% higher for the RP-LC. The alternative established represents a contribution towards the replacement of the animals improving the quality control and assuring the safety and efficacy of the biological product. / Eritropoietina é uma glicoproteína que estimula a eritropoiese e é usada clinicamente para o tratamento de anemias associadas à falência renal crônica. No presente trabalho foram validados métodos biológico e cromatográfico para a avaliação de potência de eritropoietina humana recombinante (rhEPO) em produtos farmacêuticos. O ensaio biológico foi validado em camundongos normocitêmicos, fêmeas, da linhagem BALB/c, com protocolo de injeções múltiplas e contagem automatizada dos reticulócitos por citometria de fluxo. A curva doseresposta foi linear (r2=0,9708) na faixa de concentração de 1 a 64 UI/mL. Paralelamente, desenvolveu-se e validou-se método por cromatografia líquida em fase reversa (CL-FR) empregando coluna Júpiter C4 (250 mm x 4,6 mm), mantida a temperatura ambiente (25°C). A fase móvel A foi composta de ácido trifluoracético 0,1% e a fase móvel B composta de acetonitrila/ácido trifluoracético 0,08% (70:30, v/v), eluída em gradiente linear: 0,1 60 min, 0 100% de B, na vazão de 0,5 mL/min e detecção no ultravioleta a 280 nm. A separação cromatográfica foi obtida no tempo de 60 min, sendo linear (r2=0,9997) na faixa de concentração de 10-150 μg/mL. Ambos procedimentos foram validados com base nos parâmetros de especificidade, linearidade, precisão, exatidão, robustez e limite de quantificação, bem como limite de detecção, avaliado na validação do método cromatográfico. Os métodos foram aplicados na avaliação de potência de rhEPO alfa e beta em produtos farmacêuticos e estudou-se a correlação entre os métodos. Demonstrou-se que as análises dos produtos farmacêuticos forneceram diferenças médias de potência 11,2 % superiores para o CL-FR. Desse modo, estabeleceu-se alternativa no contexto da substituição do uso de animais, contribuindo para aprimorar o controle da qualidade, garantindo a segurança e eficácia terapêutica do produto biológico.Eritropoietina é uma glicoproteína que estimula a eritropoiese e é usada clinicamente para o tratamento de anemias associadas à falência renal crônica. No presente trabalho foram validados métodos biológico e cromatográfico para a avaliação de potência de eritropoietina humana recombinante (rhEPO) em produtos farmacêuticos. O ensaio biológico foi validado em camundongos normocitêmicos, fêmeas, da linhagem BALB/c, com protocolo de injeções múltiplas e contagem automatizada dos reticulócitos por citometria de fluxo. A curva doseresposta foi linear (r2=0,9708) na faixa de concentração de 1 a 64 UI/mL. Paralelamente, desenvolveu-se e validou-se método por cromatografia líquida em fase reversa (CL-FR) empregando coluna Júpiter C4 (250 mm x 4,6 mm), mantida a temperatura ambiente (25°C). A fase móvel A foi composta de ácido trifluoracético 0,1% e a fase móvel B composta de acetonitrila/ácido trifluoracético 0,08% (70:30, v/v), eluída em gradiente linear: 0,1 60 min, 0 100% de B, na vazão de 0,5 mL/min e detecção no ultravioleta a 280 nm. A separação cromatográfica foi obtida no tempo de 60 min, sendo linear (r2=0,9997) na faixa de concentração de 10-150 μg/mL. Ambos procedimentos foram validados com base nos parâmetros de especificidade, linearidade, precisão, exatidão, robustez e limite de quantificação, bem como limite de detecção, avaliado na validação do método cromatográfico. Os métodos foram aplicados na avaliação de potência de rhEPO alfa e beta em produtos farmacêuticos e estudou-se a correlação entre os métodos. Demonstrou-se que as análises dos produtos farmacêuticos forneceram diferenças médias de potência 11,2 % superiores para o CL-FR. Desse modo, estabeleceu-se alternativa no contexto da substituição do uso de animais, contribuindo para aprimorar o controle da qualidade, garantindo a segurança e eficácia terapêutica do produto biológico.

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